MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Beilstein Journal of Organic Chemistry' source. Thu, 11 Mar 2010 17:36:13 +0100 http://www.medworm.com/index.php?rid=3353616&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-25.pdf Abstract An efficient synthesis of the angiotensin II receptor antagonist Telmisartan (1) is presented involving a cross coupling of 4-formylphenylboronic acid 10 with 2-(2-bromophenyl)-4,4-dimethyl-2-oxazoline (11) as the key step (90% yield). The benzimidazole moiety 15 was constructed regioselectively via a reductive amination-condensation sequence, replacing the alkylation of the preformed benzimidazole step in the previously published route. This methodology overcomes many of drawbacks associated with previously reported syntheses. Beilstein J. Org. Chem. 2010, 6, No. 25.  doi:10.3762/bjoc.6.25 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3353616 Thu, 11 Mar 2010 00:00:00 +0100 3353616 http://www.medworm.com/index.php?rid=3341850&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-24.pdf Abstract Sialic acids are located at the termini of mammalian cell-surface glycostructures, which participate in essential interaction processes including adhesion of pathogens prior to infection and immunogenicity. Here we present the synthesis and bioorthogonal metabolic incorporation of the sialic acid analogue N-(1-oxohex-5-ynyl)neuraminic acid (Neu5Hex) into the cell-surface glycocalyx of a human larynx carcinoma cell line (HEp 2) and its fluorescence labelling by click chemistry. Beilstein J. Org. Chem. 2010, 6, No. 24.  doi:10.3762/bjoc.6.24 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3341850 Mon, 08 Mar 2010 00:00:00 +0100 3341850 http://www.medworm.com/index.php?rid=3330674&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-23.pdf Abstract In previous studies we found that the asymmetric induction of bis(oxazolines) based on D-glucosamine strongly depended on the steric demand of the 3-O-substituents. To further probe the impact of the 3-position of the pyranose scaffold, we prepared 3-epimerised and 3-defunctionalised versions of these ligands as well as a 3-O-formyl derivative. Application of these new ligands in asymmetric cyclopropanation revealed strong steric and configurational effects of position 3 on asymmetric induction, further dramatic effects of the pyranose conformation were also observed. Beilstein J. Org. Chem. 2010, 6, No. 23.  doi:10.3762/bjoc.6.23 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3330674 Thu, 04 Mar 2010 00:00:00 +0100 3330674 http://www.medworm.com/index.php?rid=3321572&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-22.pdf Abstract The silyl enol ether derivatives of ketones or esters tethered by a hydrocarbon or ether linkage to the 3-position of a pyridine ring undergo dearomatising nucleophilic attack on the ring once it is activated (as an acylpyridinium species) by the addition of methyl chloroformate. The bicyclic dihydropyridine products are in some cases unstable, but may be isolated after hydrogenation as fused bicyclic piperidines. Beilstein J. Org. Chem. 2010, 6, No. 22.  doi:10.3762/bjoc.6.22 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3321572 Tue, 02 Mar 2010 00:00:00 +0100 3321572 http://www.medworm.com/index.php?rid=3317896&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-21.pdf Abstract N-Alkylation at the ring nitrogen of the D-galactosidase inhibitor 1-deoxygalactonojirimycin with a functionalised C6 alkyl chain followed by modification with different aromatic substituents provided lipophilic 1-deoxygalactonojirimycin derivatives which exhibit inhibitory properties against β-glycosidases from E. coli and Agrobacterium sp. as well as green coffee bean α-galactosidase. In preliminary studies, these compounds also showed potential as chemical chaperones for GM1-gangliosidosis related β-galactosidase mutants. Beilstein J. Org. Chem. 2010, 6, No. 21.  doi:10.3762/bjoc.6.21 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3317896 Mon, 01 Mar 2010 00:00:00 +0100 3317896 http://www.medworm.com/index.php?rid=3345842&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-19.pdf Abstract The arylation of bicyclic oxathiane glycosyl donors has been achieved using benzyne generated in situ from 1-aminobenzotriazole (1-ABT) and lead tetraacetate. Following sulfur arylation, glycosylation of acetate ions proceeded with high levels of stereoselectivity to afford α-glycosyl acetates in a ‘one-pot’ reaction, even in the presence of alternative acceptor alcohols. Beilstein J. Org. Chem. 2010, 6, No. 19.  doi:10.3762/bjoc.6.19 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3345842 Mon, 22 Feb 2010 00:00:00 +0100 3345842 http://www.medworm.com/index.php?rid=3341851&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-16.pdf Beilstein J. Org. Chem. 2010, 6, No. 16.  doi:10.3762/bjoc.6.16 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3341851 Mon, 22 Feb 2010 00:00:00 +0100 3341851 http://www.medworm.com/index.php?rid=3293888&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-17.pdf This study constitutes a particularly efficient and convergent preparation of these three Lex analogues. Beilstein J. Org. Chem. 2010, 6, No. 17.  doi:10.3762/bjoc.6.17 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3293888 Mon, 22 Feb 2010 00:00:00 +0100 3293888 http://www.medworm.com/index.php?rid=3293887&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-18.pdf Abstract α,2-3- and α,2-6-sialylated lactosaminide precursor structures obtained by various enzymatic procedures could be used for glycosylations employing triflic acid/N-iodosuccinimide. Easily accessible selectively protected lactoside derivatives served as acceptor disaccharides to give the corresponding human milk pentasaccharides in good yields. These could be characterized by spectroscopic means in form of their peracetylated derivatives. Beilstein J. Org. Chem. 2010, 6, No. 18.  doi:10.3762/bjoc.6.18 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3293887 Mon, 22 Feb 2010 00:00:00 +0100 3293887 http://www.medworm.com/index.php?rid=3293886&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-19.pdf Abstract The arylation of bicyclic oxathiane glycosyl donors has been achieved using benzyne generated in situ from 1-aminobenzotriazole (1-ABT) and lead tetraacetate. Following sulfur arylation, glycosylation of acetate ions proceeded with high levels of stereoselectivity to afford α-glycosyl acetates in a ‘one-pot’ reaction, even in the presence of alternative acceptor alcohols. Beilstein J. Org. Chem. 2010, 6, No. 19.  doi:10.3762/bjoc.6.19 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3293886 Mon, 22 Feb 2010 00:00:00 +0100 3293886 http://www.medworm.com/index.php?rid=3293885&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-20.pdf Abstract Oligosaccharides are currently recognised as having functions that influence the entire spectrum of cell activities. However, a distinct disadvantage of naturally occurring oligosaccharides is their metabolic instability in biological systems. Therefore, much effort has been spent in the past two decades on the development of feasible routes to carbohydrate mimetics which can compete with their O-glycosidic counterparts in cell surface adhesion, inhibit carbohydrate processing enzymes, and interfere in the biosynthesis of specific cell surface carbohydrates. Such oligosaccharide mimetics are potential therapeutic agents against HIV and other infections, against cancer, diabetes and other metabolic diseases. An efficient strategy to access this type of compound is the replacement o... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3293885 Mon, 22 Feb 2010 00:00:00 +0100 3293885 http://www.medworm.com/index.php?rid=3341852&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-15.pdf Abstract A new class of aminocyclitol derivatives with the bicyclo[4.2.0]octane skeleton was synthesized starting from cyclooctatetraene. Photooxygenation of trans-7,8-diacetoxy- and cis-7,8-dichlorobicyclo[4.2.0]octa-2,4-diene afforded the bicyclic endoperoxides. Reduction of the latter with thiourea followed by a Pd(0) catalyzed ionization/cyclization reaction gave the corresponding oxazolidinone derivatives. Oxidation of the double bond with KMnO4 or OsO4 followed by acetylation gave the acetate derivatives, the exact configuration of which was determined by spectroscopic methods. Hydrolysis of the oxazolidinone rings and removal of the acetate groups furnished the desired aminocyclitols. Beilstein J. Org. Chem. 2010, 6, No. 15.  doi:10.3762/bjoc.6.15 (Source: Beilstein Journ... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3341852 Mon, 15 Feb 2010 00:00:00 +0100 3341852 http://www.medworm.com/index.php?rid=3272436&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-15.pdf Abstract A new class of aminocyclitol derivatives with the bicyclo[4.2.0]octane skeleton were synthesized starting from cyclooctatetraene. Photooxygenation of trans-7,8-diacetoxy- and cis-7,8-dichlorobicyclo[4.2.0]octa-2,4-diene afforded the bicyclic endoperoxides. Reduction of the latter with thiourea followed by a Pd(0) catalyzed ionization/cyclization reaction gave the corresponding oxazolidinone derivatives. Oxidation of the double bond with KMnO4 or OsO4 followed by acetylation gave the acetate derivatives the exact configuration of which was determined by spectroscopic methods. Hydrolysis of the oxazolidinone rings and removal of the acetate groups furnished the desired aminocyclitols. Beilstein J. Org. Chem. 2010, 6, No. 15.  doi:10.3762/bjoc.6.15 (Source: Beilstein Journ... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3272436 Mon, 15 Feb 2010 00:00:00 +0100 3272436 http://www.medworm.com/index.php?rid=3317897&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-14.pdf Abstract Two procedures for the synthesis of benzo-21-crown-7 have been explored. The [1+1] macrocyclization with KBF4 as the template was found to be more efficient than the intramolecular macrocyclization without template. Pseudorotaxanes form with secondary ammonium ions bearing at least one alkyl chain narrow enough to slip into the crown ether. Substitution on benzo-21-crown-7 or on the secondary ammonium axle alters the binding affinity and binding mode. Compared to dibenzo-24-crown-8, the complexing properties of benzo-21-crown-7 turn out to be more susceptible to modifications at the crown periphery. Beilstein J. Org. Chem. 2010, 6, No. 14.  doi:10.3762/bjoc.6.14 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3317897 Thu, 11 Feb 2010 00:00:00 +0100 3317897 http://www.medworm.com/index.php?rid=3282932&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-13.pdf Abstract The Nile Blue chromophore was incorporated into oligonucleotides using “click” chemistry for the postsynthetic modification of oligonucleotides. These were synthesized using DNA building block 3 bearing an alkyne group and reacted with the azide 4. (R)-3-amino-1,2-propanediol was applied as the linker between the phosphodiester bridges. Two sets of DNA duplexes were prepared. One set carried the chromophore in an A-T environment, the second set in a G-C environment. Both were characterized by optical spectroscopy. Sequence-dependent fluorescence quenching was applied as a sensitive tool to compare the stacking interactions with respect to the chirality of the acyclic linker attachment. The results were compared to recent results from duplexes that carried the Nile Blue... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3282932 Tue, 09 Feb 2010 00:00:00 +0100 3282932 http://www.medworm.com/index.php?rid=3253824&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-13.pdf Abstract The Nile Blue chromophore was incorporated into oligonucleotides using “click” chemistry for the postsynthetic modification of oligonucleotides. These were synthesized using DNA building block 3 bearing an alkyne group and reacted with the azide 4. (R)-3-amino-1,2-propanediol was applied as the linker between the phosphodiester bridges. Two sets of DNA duplexes were prepared. One set carried the chromophore in an A-T environment, the second set in a G-C environment. Both were characterized by optical spectroscopy. Sequence-dependent fluorescence quenching was applied as a sensitive tool to compare the stacking interactions with respect to the chirality of the acyclic linker attachment. The results were compared to recent results from duplexes that carried the Nile Blue... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3253824 Tue, 09 Feb 2010 00:00:00 +0100 3253824 http://www.medworm.com/index.php?rid=3293890&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-12.pdf Abstract A novel indolocarbazole-based chemosensor 1 containing hydrogen bond donor moieties has been established as a selective colorimetric and fluorometric sensor for F− in CH3CN/H2O (4:1 v/v). Upon the addition of a series of tetrabutylammonium salts to receptor 1 in aqueous CH3CN, only when the counter ion was F− was a significant color change (from light violet to dark orange) observed. Beilstein J. Org. Chem. 2010, 6, No. 12.  doi:10.3762/bjoc.6.12 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3293890 Mon, 08 Feb 2010 00:00:00 +0100 3293890 http://www.medworm.com/index.php?rid=3275294&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-11.pdf Abstract Some novel annulated pyrido[2,3-d]pyrimidines 6 and 7 were synthesized stereoselectively by intramolecular hetero Diels–Alder reactions involving 1-oxa-1,3-butadienes. Beilstein J. Org. Chem. 2010, 6, No. 11.  doi:10.3762/bjoc.6.11 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3275294 Thu, 04 Feb 2010 00:00:00 +0100 3275294 http://www.medworm.com/index.php?rid=3238825&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-11.pdf Abstract Some novel annulated pyrido[2,3-d]pyrimidines 6 and 7 were synthesized stereoselectively by intramolecular hetero Diels–Alder reactions involving 1-oxa-1,3-butadienes. Beilstein J. Org. Chem. 2010, 6, No. 11.  doi:10.3762/bjoc.6.11 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3238825 Thu, 04 Feb 2010 00:00:00 +0100 3238825 http://www.medworm.com/index.php?rid=3279325&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-10.pdf Abstract A bis(resorcinarene) substituted 2,2′-bipyridine was found to bind weakly to small esters like ethyl acetate whereas more bulky esters were not recognized by this hemicarcerand. This size selective molecular recognition could be controlled by a negative cooperative allosteric effect: coordination of a triscarbonyl rhenium chloride fragment to the bipyridine causes a conformational rearrangement that orientates the resorcinarene moieties in different directions so that they cannot act cooperatively in the binding of the substrate. Beilstein J. Org. Chem. 2010, 6, No. 10.  doi:10.3762/bjoc.6.10 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3279325 Wed, 03 Feb 2010 00:00:00 +0100 3279325 http://www.medworm.com/index.php?rid=3235043&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-10.pdf Abstract A bis(resorcinarene) substituted 2,2’-bipyridine was found to bind weakly to small esters like ethyl acetate whereas more bulky esters were not recognized by this hemicarcerand. This size selective molecular recognition could be controlled by a negative cooperative allosteric effect: coordination of a triscarbonyl rhenium chloride fragment to the bipyridine causes a conformational rearrangement that orientates the resorcinarene moieties in different directions so that they cannot act cooperatively in the binding of the substrate. Beilstein J. Org. Chem. 2010, 6, No. 10.  doi:10.3762/bjoc.6.10 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3235043 Wed, 03 Feb 2010 00:00:00 +0100 3235043 http://www.medworm.com/index.php?rid=3282933&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-9.pdf Abstract Compounds 4 and 5, including both 4(5)-substituted imidazole or 3-substituted indole units as the entities used in nature, and 2-aminopyridine group as a heterocyclic analogue of the asparagine/glutamine primary amide side chain, were prepared and their binding properties towards carbohydrates were studied. The design of these receptors was inspired by the binding motifs observed in the crystal structures of protein–carbohydrate complexes. 1H NMR spectroscopic titrations in competitive and non-competitive media as well as binding studies in two-phase systems, such as dissolution of solid carbohydrates in apolar media, revealed both highly effective recognition of neutral carbohydrates and interesting binding preferences of these acyclic compounds. Compared to the previo... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3282933 Tue, 02 Feb 2010 00:00:00 +0100 3282933 http://www.medworm.com/index.php?rid=3230716&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-9.pdf Abstract Compounds 4 and 5, including both 4(5)-substituted imidazole or 3-substituted indole units as the entities used in nature, and 2-aminopyridine group as a heterocyclic analogue of the asparagine/glutamine primary amide side chain, were prepared and their binding properties towards carbohydrates were studied. The design of these receptors was inspired by the binding motifs observed in the crystal structures of protein–carbohydrate complexes. 1H NMR spectroscopic titrations in competitive and non-competitive media as well as binding studies in two-phase systems, such as dissolution of solid carbohydrates in apolar media, revealed both highly effective recognition of neutral carbohydrates and interesting binding preferences of these acyclic compounds. Compared to the previously ... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3230716 Tue, 02 Feb 2010 00:00:00 +0100 3230716 http://www.medworm.com/index.php?rid=3262090&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-8.pdf Abstract The total synthesis of (3R,5R)-harzialactone A (1) and its (3R,5S)-isomer (2) is described. Epoxide opening with thioacetal and diastereoselective reductions are used as key reactions. Beilstein J. Org. Chem. 2010, 6, No. 8.  doi:10.3762/bjoc.6.8 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3262090 Fri, 29 Jan 2010 00:00:00 +0100 3262090 http://www.medworm.com/index.php?rid=3219689&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-8.pdf Abstract The total synthesis of (3R,5R)-harzialactone A 1 and its (3R,5S)-isomer (2) is described. Epoxide opening with thioacetal and diastereoselective reductions are used as key reactions. Beilstein J. Org. Chem. 2010, 6, No. 8.  doi:10.3762/bjoc.6.8 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3219689 Fri, 29 Jan 2010 00:00:00 +0100 3219689 http://www.medworm.com/index.php?rid=3250574&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-7.pdf Abstract Although a plethora of synthetic procedures mediated by KF-loaded aluminas is available in the literature, there is almost no data concerning the influence of parameters such as alumina modification or KF-loading on experimental results. Hence, the Pd-catalyzed, solvent-free Suzuki–Miyaura reaction was chosen as model reaction to investigate the effect of the above mentioned parameters on the results of coupling reactions. The results from ball milling experiments led to the conclusion that self-prepared and commercially available KF–Al2O3 differ in water content. The higher the residual water content, the higher are the product yields. Beilstein J. Org. Chem. 2010, 6, No. 7.  doi:10.3762/bjoc.6.7 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3250574 Fri, 22 Jan 2010 00:00:00 +0100 3250574 http://www.medworm.com/index.php?rid=3258108&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-6.pdf Abstract The development of efficient Friedel–Crafts alkylations of arenes and heteroarenes using only catalytic amounts of a Lewis acid has gained much attention over the last decade. The new catalytic approaches described in this review are favoured over classical Friedel–Crafts conditions as benzyl-, propargyl- and allyl alcohols, or styrenes, can be used instead of toxic benzyl halides. Additionally, only low catalyst loadings are needed to provide a wide range of products. Following a short introduction about the origin and classical definition of the Friedel–Crafts reaction, the review will describe the different environmentally benign substrates which can be applied today as an approach towards greener processes. Additionally, the first diastereoselective and enant... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3258108 Wed, 20 Jan 2010 00:00:00 +0100 3258108 http://www.medworm.com/index.php?rid=3188452&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-6.pdf Abstract The development of efficient Friedel–Crafts alkylations of arenes and heteroarenes using only catalytic amounts of a Lewis acid has gained much attention over the last decade. The new catalytic approaches described in this review are favoured over classical Friedel–Crafts conditions as benzyl-, propargyl- and allyl alcohols, or styrenes, can be used instead of toxic benzyl halides. Additionally, only low catalyst loadings are needed to provide a wide range of products. Following a short introduction about the origin and classical definition of the Friedel–Crafts reaction, the review will describe the different environmentally benign substrates which can be applied today as an approach towards greener processes. Additionally, the first diastereoselective and enant... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3188452 Wed, 20 Jan 2010 00:00:00 +0100 3188452 http://www.medworm.com/index.php?rid=3184819&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-5.pdf We present here the design, synthesis, and analysis of a series of receptors for peptide ligands inspired by the hydrogen-bonding pattern of protein β-sheets. The receptors themselves can be regarded as strands 1 and 3 of a three-stranded β-sheet, with cross-linking between the chains through the 4-position of adjacent phenylalanine residues. We also report on the conformational equilibria of these receptors in solution as well as on their tendency to dimerize. 1H NMR titration experiments are used to quantify the dimerization constants, as well as the association constant values of the 1:1 complexes formed between the receptors and a series of diamides and dipeptides. The receptors show moderate levels of selectivity in the molecular recognition of the hydrogen-bonding pattern p... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3184819 Tue, 19 Jan 2010 00:00:00 +0100 3184819 http://www.medworm.com/index.php?rid=3175105&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-4.pdf Abstract The series of haloanilinium and halopyridinium salts: 4-IPhNH3Cl (1), 4-IPhNH3Br (5), 4-IPhNH3H2PO4 (6), 4-ClPhNH3H2PO4 (8), 3-IPyBnCl (9), 3-IPyHCl (10) and 3-IPyH-5NIPA (3-iodopyridinium 5-nitroisophthalate, 13), where hydrogen or/and halogen bonding represents the most relevant non-covalent interactions, has been prepared and characterized by single crystal X-ray diffraction. This series was further complemented by extracting some relevant crystal structures: 4-BrPhNH3Cl (2, CCDC ref. code TAWRAL), 4-ClPhNH3Cl (3, CURGOL), 4-FPhNH3Cl (4, ANLCLA), 4-BrPhNH3H2PO4, (7, UGISEI), 3-BrPyHCl, (11, CIHBAX) and 3-ClPyHCl, (12, VOQMUJ) from Cambridge Structural Database for sake of comparison. Based on the X-ray data it was possible to highlight the balance between non-covalent forces ac... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3175105 Fri, 15 Jan 2010 00:00:00 +0100 3175105 http://www.medworm.com/index.php?rid=3250575&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-3.pdf Abstract The indole based zwitterion 2 forms stable dimers held together by H-bond assisted ion pairs. Dimerisation was confirmed in the solid state and studied in solution using dilution NMR experiments. Even though zwitterion 2 forms very stable dimers even in DMSO, their stability is lower than of an analogous pyrrole based zwitterion 1. As revealed by the X-ray crystal structure the two binding sites in 2 cannot be planar due to steric interactions between the guanidinium group and a neighbouring aromatic CH. Hence the guanidinium moiety is twisted out of planarity from the rest of the molecule forcing the two monomers in dimer 2·2 to interact in a non-ideal orientation. Furthermore, the acidity of the NHs is lower than in 1 (as determined by UV-pH-titration) also leading to less ... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3250575 Thu, 14 Jan 2010 00:00:00 +0100 3250575 http://www.medworm.com/index.php?rid=3170832&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-3.pdf Abstract The indole based zwitterion 2 forms stable dimers held together by H-bond assisted ion pairs. Dimerisation was confirmed in the solid state and studied in solution using dilution NMR experiments. Even though zwitterion 2 forms very stable dimers even in DMSO, their stability is lower than of an analogous pyrrole based zwitterion 1. As revealed by the X-ray crystal structure the two binding sites in 2 cannot be planar due to steric interactions between the guanidinium group and a neighbouring aromatic CH. Hence the guanidinium moiety is twisted out of planarity from the rest of the molecule forcing the two monomers in dimer 2·2 to interact in a non-ideal orientation. Furthermore, the acidity of the NHs is lower than in 1 (as determined by UV-pH-titration) also leading to less ... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3170832 Thu, 14 Jan 2010 00:00:00 +0100 3170832 http://www.medworm.com/index.php?rid=3148528&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-6-2.pdf Abstract We study the influence of external electric or magnetic field B on orientational ordering of nematic liquid crystals or of other rod-like objects (e.g. nanotubes immersed in a liquid) in the presence of random anisotropy field type of disorder. The Lebwohl–Lasher lattice type of semi-microscopic approach is used at zero temperature. Therefore, results are valid well below the transition into the isotropic phase. We calculate the correlation function of systems as a function of B, concentration p of impurities imposing random anisotropy field disorder, the disorder strength W and system dimensionality (2D and 3D systems). In order to probe memory effects we calculate correlation length ξ for random and homogeneous initial configurations. We determine the crossover fields... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3148528 Thu, 07 Jan 2010 00:00:00 +0100 3148528 http://www.medworm.com/index.php?rid=3184820&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-6-1.pdf Beilstein J. Org. Chem. 2010, 6, No. 1.  doi:10.3762/bjoc.6.1 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3184820 Wed, 06 Jan 2010 00:00:00 +0100 3184820 http://www.medworm.com/index.php?rid=3227091&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-83.pdf Abstract The effect of the phenyl–alkyl connecting group on mesogenic properties of several series of isostructural compounds containing p-carborane (A and B), bicyclo[2.2.2]octane (C), and benzene (D) was investigated using thermal and optical methods. Results demonstrated that mesophase stability in the series containing A–D follows the order (Alk)CH2CH2– < (Alk)OOC– < (Alk)CH2O– < (Alk)COO–. Surprisingly, the connecting groups (Alk)CH2CH2– and (Alk)OOC– destabilize the mesophase significantly stronger for carboranes (A and B) than for carbocyclic derivatives (C and D). Analysis indicates that this effect may have quadrupolar and conformational origin. Beilstein J. Org. Chem. 2009, 5, No. 83.  doi:10.3762/bjoc.5.83 (Sour... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3227091 Wed, 30 Dec 2009 00:00:00 +0100 3227091 http://www.medworm.com/index.php?rid=3128636&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-83.pdf Abstract The effect of the phenyl–alkyl connecting group on mesogenic properties of several series of isostructural compounds containing p-carborane (A and B), bicyclo[2.2.2]octane (C), and benzene (D) was investigated using thermal and optical methods. Results demonstrated that mesophase stability in the series containing A–D follows the order (Alk)CH2CH2– < (Alk)OOC– < (Alk)CH2O– < (Alk)COO–. Surprisingly, the connecting groups (Alk)CH2CH2– and (Alk)OOC– destabilize the mesophase significantly stronger for carboranes (A and B) than for carbocyclic derivatives (C and D). Analysis indicates that this effect may have quadrupolar and conformational origin. Beilstein J. Org. Chem. 2009, 5, No. 83.  doi:10.3762/bjoc.5.83 (Sour... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3128636 Wed, 30 Dec 2009 00:00:00 +0100 3128636 http://www.medworm.com/index.php?rid=3227092&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-82.pdf Abstract The electron affinities (EAs) of a training set of 19 metal-salen compounds were calculated using density functional theory. Concurrently, the experimental reduction potentials for the training set were measured using cyclic voltammetry. The EAs and reduction potentials were found to be linearly correlated by metal. The reduction potentials of a test set of 14 different metal-salens were then measured and compared to the predicted reduction potentials based upon the training set correlation. The method was found to work well, with a mean unsigned error of 99 mV for the entire test set. This method could be used to predict the reduction potentials of a variety of metal-salen compounds, an important class of coordination compounds used in synthetic organic electrochemistry as electr... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3227092 Wed, 23 Dec 2009 00:00:00 +0100 3227092 http://www.medworm.com/index.php?rid=3114377&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-82.pdf Abstract The electron affinities (EAs) of a training set of 19 metal-salen compounds were calculated using density functional theory. Concurrently, the experimental reduction potentials for the training set were measured using cyclic voltammetry. The EAs and reduction potentials were found to be linearly correlated by metal. The reduction potentials of a test set of 14 different metal-salens were then measured and compared to the predicted reduction potentials based upon the training set correlation. The method was found to work well, with a mean unsigned error of 99 mV for the entire test set. This method could be used to predict the reduction potentials of a variety of metal-salen compounds, an important class of coordination compounds used in synthetic organic electrochemistry as electr... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3114377 Wed, 23 Dec 2009 00:00:00 +0100 3114377 http://www.medworm.com/index.php?rid=3197034&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-81.pdf Abstract An enantioselective route to four tricyclic amino acids and N-tosylamides, composed of a central norbornane framework with a 2-endo,3-endo-annelated pyrrolidine ring and a 5-endo-C1 or -C2 side chain, has been developed. A key intermediate was the chiral, N-Boc-protected ketone (1R,2S,6S,7R)-4-azatricyclo[5.2.1.02,6]decan-8-one, available from inexpensive endo-carbic anhydride in five steps and 47% yield. The rigid scaffold makes these amino acid derivatives promising candidates for β-turn-inducing building blocks in peptidomimetics and for chiral auxiliaries in asymmetric organocatalysis. Beilstein J. Org. Chem. 2009, 5, No. 81.  doi:10.3762/bjoc.5.81 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3197034 Mon, 21 Dec 2009 00:00:00 +0100 3197034 http://www.medworm.com/index.php?rid=3192942&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-80.pdf Abstract A synthesis of (±)-cherylline dimethyl ether is reported. The key steps involved are Michael-type addition, radical azidonation of an aldehyde, Curtius rearrangement, and reduction of an isocyanate intermediate followed by Pictet–Spengler cyclization. Beilstein J. Org. Chem. 2009, 5, No. 80.  doi:10.3762/bjoc.5.80 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3192942 Wed, 16 Dec 2009 00:00:00 +0100 3192942 http://www.medworm.com/index.php?rid=3178282&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-79.pdf Abstract The extensively studied trans-stilbene molecule is known to give only weak fluorescence in solution and inside loosely-fitting synthetic capsules. However, trans-stilbene has been recently studied in the context of antibody interiors, where binding results in strong blue fluorescence. The present research was undertaken to understand the spatial factors that influence stilbene fluorescence. trans-Stilbene was encapsulated in the snug, self-assembled complex 1.1 and exhibited fluorescence quenching due to the distortion of its ground-state geometry. When the complex is elongated by incorporating glycouril spacers, trans-stilbene is allowed to adapt a fully coplanar arrangement and fluorescence returns. Beilstein J. Org. Chem. 2009, 5, No. 79.  doi:10.3762/bjoc.5.79 (Sour... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3178282 Fri, 11 Dec 2009 00:00:00 +0100 3178282 http://www.medworm.com/index.php?rid=3175106&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-78.pdf Abstract A facile synthesis of a highly preorganized tripodal enterobactine-type ligand 1a-H3 consisting of a chiral C3-symmetric macrocyclic peptide and three tridentate 2-amido-8-hydroxyquinoline coordinating units is presented. Complex formation with various metal ions (Al3+, Ga3+, Fe3+, La3+ and Eu3+) was investigated by spectrophotometric methods. Only in the case of La3+ and Eu3+ were well defined 1 : 1 complexes formed. On the basis of CD spectroscopy and DFT calculations the configuration at the metal centre of the La3+ complex was determined to show Λ helicity. The coordination compounds [(1a)Ln] presented should be prototypes for further lanthanide(III) complexes with an enterobactine analogue binding situation. Beilstein J. Org. Chem. 2009, 5, No. 78.  doi:10.376... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3175106 Fri, 11 Dec 2009 00:00:00 +0100 3175106 http://www.medworm.com/index.php?rid=3141714&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-76.pdf Beilstein J. Org. Chem. 2009, 5, No. 76.  doi:10.3762/bjoc.5.76 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3141714 Fri, 11 Dec 2009 00:00:00 +0100 3141714 http://www.medworm.com/index.php?rid=3078475&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-77.pdf Abstract Crystal engineering studies confirm that the zinc-tetra(4-pyridyl)porphyrin building block reveals versatile supramolecular chemistry. In this work, it was found to be reactive in the assembly of both (a) a 2D polymeric array by a unique combination of self-coordination and coordination through external zinc dichloride linkers and (b) an extended heteromolecular hydrogen-bonded network with mellitic acid sustained by multiple connectivity between the component species. Beilstein J. Org. Chem. 2009, 5, No. 77.  doi:10.3762/bjoc.5.77 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3078475 Fri, 11 Dec 2009 00:00:00 +0100 3078475 http://www.medworm.com/index.php?rid=3078474&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-78.pdf Abstract A facile synthesis of a highly preorganized tripodal enterobactine-type ligand 1a-H3 consisting of a chiral C3-symmetric macrocyclic peptide and three tridentate 2-amido-8-hydroxyquinoline coordinating units is presented. Complex formation with various metal ions (Al3+, Ga3+, Fe3+, La3+ and Eu3+) was investigated by spectrophotometric methods. Only in the case of La3+ and Eu3+ were well defined 1 : 1 complexes formed. On the basis of CD spectroscopy and DFT calculations the configuration at the metal centre of the La3+ complex was determined to show Λ helicity. The coordination compounds [(1a)Ln] presented should be prototypes for further lanthanide(III) complexes with an enterobactine analogue binding situation. Beilstein J. Org. Chem. 2009, 5, No. 78.  doi:10.376... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3078474 Fri, 11 Dec 2009 00:00:00 +0100 3078474 http://www.medworm.com/index.php?rid=3078473&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-79.pdf Abstract The extensively studied trans-stilbene molecule is known to give only weak fluorescence in solution and inside loosely-fitting synthetic capsules. However, trans-stilbene has been recently studied in the context of antibody interiors, where binding results in strong blue fluorescence. The present research was undertaken to understand the spatial factors that influence stilbene fluorescence. trans-Stilbene was encapsulated in the snug, self-assembled complex 1.1 and exhibited fluorescence quenching due to the distortion of its ground-state geometry. When the complex is elongated by incorporating glycouril spacers, trans-stilbene is allowed to adapt a fully coplanar arrangement and fluorescence returns. Beilstein J. Org. Chem. 2009, 5, No. 79.  doi:10.3762/bjoc.5.79 (Sour... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3078473 Fri, 11 Dec 2009 00:00:00 +0100 3078473 http://www.medworm.com/index.php?rid=3145231&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-75.pdf Abstract In a solvent-free phase-vanishing reaction with PTFE (polytetrafluoroethylene, Teflon®) tape as the phase screen, a thermometer adapter is utilized to insert a PTFE-sealed tube into the vapor phase above the substrate. Besides avoiding use of solvents, the experimental design is not dependent upon the densities of the reactants and the procedure generates little or no waste while providing the reaction products in high yield and in high purity. Beilstein J. Org. Chem. 2009, 5, No. 75.  doi:10.3762/bjoc.5.75 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3145231 Wed, 09 Dec 2009 00:00:00 +0100 3145231 http://www.medworm.com/index.php?rid=3138697&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-74.pdf Abstract The synthesis of [3.3]dithia-bridged cyclophanes 7, 9 and 11 incorporating a fused heterocycle, thieno[2,3-b]thiophene is described. The structures are established by 1H NMR analysis and, in the case of 11, also by single crystal X-ray crystallography. Conformational analysis by variable temperature NMR suggests that cyclophanes 7, 9 and 11 exhibit conformationally rigid bridges and rings at least up to 130 °C. Energy minimization of 11 revealed anti-11 to be the most stable conformation. Although, the computed energy difference between the most stable conformation anti-11 and the next higher energy conformation syn-anti-11 is only 2.98 kJ/mol, it is intriguing that 11 does not exhibit thia-bridge inversion even at elevated temperatures. Beilstein J. Org. Chem. 2009, 5, No. ... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3138697 Tue, 08 Dec 2009 00:00:00 +0100 3138697 http://www.medworm.com/index.php?rid=3066312&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-74.pdf Abstract The synthesis of [3.3]dithia-bridged cyclophanes 7, 9 and 11 incorporating a fused heterocycle, thieno[2,3-b]thiophene is described. The structures are established by 1H NMR analysis and, in the case of 11, also by single crystal X-ray crystallography. Conformational analysis by variable temperature NMR suggests that cyclophanes 7, 9 and 11 exhibit conformationally rigid bridges and rings at least up to 130 °C. Energy minimization of 11 revealed anti-11 to be the most stable conformation. Although, the computed energy difference between the most stable conformation anti-11 and the next higher energy conformation syn-anti-11 is only 2.98 kJ/mol, it is intriguing that 11 does not exhibit thia-bridge inversion even at elevated temperatures. Beilstein J. Org. Chem. 2009, 5, No. ... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3066312 Tue, 08 Dec 2009 00:00:00 +0100 3066312 http://www.medworm.com/index.php?rid=3055804&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-73.pdf Abstract A series of V-shaped, shape-persistent thiadiazole nematogens, based on an oligo(phenylene ethynylene) scaffold with ester groups connected via alkyloxy spacers, was efficiently prepared by a two-step procedure. Phase engineering results in an optimum of the mesophase range and low melting temperature when the nematogens are desymmetrised with a butoxy and a heptyloxy spacer. The mesophases are enantiotropic and over the whole temperature range nematic. For the optimised mesogen structure, optical investigations by conoscopy monitored a uniaxial nematic phase upon cooling from the isotropic phase to room temperature (ΔT = 150 °C). X-ray studies on magnetic-field-aligned samples of this mesogen family revealed a general pattern, indicating the alignment of two molecular a... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3055804 Fri, 04 Dec 2009 00:00:00 +0100 3055804 http://www.medworm.com/index.php?rid=3047534&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-72.pdf Abstract Novel N-alkyl-N-(phosphonoethyl) substituted mono-, bis- and tris(meth)acrylamides 3 were synthesized by two different three-step reactions and characterized by IR, 1H NMR and 13C NMR spectroscopy as well as refractive index and viscosity. The phosphonoethyl substituted (meth)acrylamide monomers show improved hydrolytic stability compared to carboxylic esters. The highest stability was found for the phosphonoethyl substituted acrylamide monomers. Acrylamides have a larger polymerization enthalpy ranging from −50 to −70 kJ·mol−1 per double bond compared to methacrylamides which show −8.57 to −25.1 kJ·mol−1 per double bond. Depending on their structure methacrylamides 3 exhibit an adhesion to enamel and dentin up to 19.5 MPa. The monomer... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3047534 Wed, 02 Dec 2009 00:00:00 +0100 3047534 http://www.medworm.com/index.php?rid=3043820&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-71.pdf Abstract Macrocycles of the bisbibenzyl-type are natural products that are found exclusively in bryophytes (liverworts). The molecular framework of the subtype “isoplagiochin” is of substantial structural interest because of the chirality of the entire molecule, which arises from two biaryl axes in combination with two helical two-carbon units in a cyclic arrangement. From a structural as well as a synthetic point of view we report on the total synthesis of compounds which possess more rigid two-carbon biaryl bridges like stilbene (E or Z) or even tolane moieties which were introduced starting with a Sonogashira protocol. The McMurry method proved to be a powerful tool for the cyclization to these considerably ring-strained macrocycles. Beilstein J. Org. Chem. 2009, 5, No. 71.... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3043820 Tue, 01 Dec 2009 00:00:00 +0100 3043820 http://www.medworm.com/index.php?rid=3039126&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-70.pdf Abstract Until recently traditional heating in organic chemistry has been done with oil heating baths or using electric heat exchangers. With the advent of microwave equipment, heating by microwaves was rapidly introduced as standard method in organic chemistry laboratories, mainly because of the convenient possibility to operate at high temperature accompanied by accelerated reaction rates. In the present contribution we discuss the method of heating small, continuously operated reactors by passing electric current directly through the reactor wall as an enabling technology in organic chemistry. The benefit of this method is that the heat is generated directly inside the reactor wall. By this means high heating rates comparable to microwave ovens can be reached but at much lower cost for ... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3039126 Mon, 30 Nov 2009 00:00:00 +0100 3039126 http://www.medworm.com/index.php?rid=3025901&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-69.pdf Abstract The cis-dibromination of unsaturated bicyclic bridgehead sultams 5a and 5b, and experiments designed to understand the cis-stereochemical outcome of these reactions, are described. In the case of 5b, a novel solvent dependent carbocation rearrangement occurs with the formation of 18b. cis-Dibromides 13a and 13b undergo regioselective dehydrobromination, and the participation of the resultant vinyl bromide 24a in lithiation and Pd-coupling chemistry is described. In the case of the latter, hydrogenation of the styryl products afforded a single diastereoisomer. These compounds were then studied under dissolved metal reduction conditions, in which the cleavage of both N–S and C–S bonds takes place to afford cis-2,4-diaryl-substituted pyrrolidines 35–37. Beilstein J... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3025901 Wed, 25 Nov 2009 00:00:00 +0100 3025901 http://www.medworm.com/index.php?rid=3011606&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-68.pdf Abstract The Knoevenagel condensation between aromatic aldehydes and malononitrile, ethyl cyanoacetate or malonic acid with hydroxyapatite supported caesium carbonate in water is described. HAP–Cs2CO3 was found to be a highly active, stable and recyclable catalyst under the reaction conditions. Beilstein J. Org. Chem. 2009, 5, No. 68.  doi:10.3762/bjoc.5.68 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3011606 Fri, 20 Nov 2009 00:00:00 +0100 3011606 http://www.medworm.com/index.php?rid=3007332&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-67.pdf Abstract Small molecule asymmetric catalysts are often described as being “good” or “bad” but to date there has been no way of comparing catalyst efficiency quantitatively. We define a simple formula, Asymmetric Catalyst Efficiency (ACE), that allows for such a comparison. We propose that a catalyst is more efficient if fewer atoms are utilised to give a product in a required enantiomeric excess. We illustrate this concept by analysing several well-known asymmetric catalytic chemical reactions carried out in academic laboratories, and compare small molecule catalysts with enzymes. We conclude that ACE is a useful descriptor for the comparison of diverse catalytic systems. It is also noteworthy that, despite the relatively short period of investigation into small mol... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=3007332 Thu, 19 Nov 2009 00:00:00 +0100 3007332 http://www.medworm.com/index.php?rid=2998885&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-66.pdf Abstract The reaction of 2-[2-(4-fluorophenyl)-2-oxo-1-phenylethyl]-4-methyl-3-oxo-pentanoic acid phenylamide with tertiary butyl carbazate and subsequent condensation of the resulting carbamate derivative with a chalcone provided a facile new approach to pyrrolo[1,2-b]pyridazine derivatives. Beilstein J. Org. Chem. 2009, 5, No. 66.  doi:10.3762/bjoc.5.66 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2998885 Tue, 17 Nov 2009 00:00:00 +0100 2998885 http://www.medworm.com/index.php?rid=2988279&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-65.pdf Abstract The phase diagrams of two mixtures of chemically similar smectogenic mesogens strongly differing in molecular length were investigated. In these mixtures the nematic phase present in the pure short mesogen disappeared rapidly on the addition of the longer mesogen, while the smectic state was preserved. In the smectic state the smectic A phase was the much more stable phase as the smectic C phase disappeared quite rapidly as well. In these compounds the loss of the smectic C phase is accompanied by a decrease in smectic translational order and very small tilt angles. This leads to a concentration induced smectic C to smectic A transition. Thus smectic A seems to be the most stable phase to accommodate mesogenic molecules of substantially different length. These surprising results a... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2988279 Fri, 13 Nov 2009 00:00:00 +0100 2988279 http://www.medworm.com/index.php?rid=2980324&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-64.pdf Abstract Pd/C-mediated alkynylation of 5-iodo-pyrazole-4-carboxylic acid, involving the first regioselective construction of α-pyrone ring on a pyrazol moiety via tandem coupling–cyclization process, has been developed to afford pyrano[4,3-c]pyrazol-4(1H)-one in a single pot. Beilstein J. Org. Chem. 2009, 5, No. 64.  doi:10.3762/bjoc.5.64 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2980324 Wed, 11 Nov 2009 00:00:00 +0100 2980324 http://www.medworm.com/index.php?rid=2973481&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-63.pdf Abstract Based on 5-(4-hydroxyphenyl)-2-octylpyrimidine 8, 5-phenylpyrimidine derivatives 3-7, 9 with different spacer chain lengths (C2 up to C6) and different terminal polar groups (Br, Cl, N3, OH, CN) were synthesized by etherification and nucleophilic substitution. The mesomorphic behaviour of these compounds was investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (WAXS and SAXS) and revealed smectic A mesophases for bromides, chlorides and azides 3, 4 and 6. For these compounds a maximum phase width was observed for the C5 spacer regardless of the terminal group, whereas the hydroxy- and cyano-substituted derivatives 5 and 7, respectively, were non mesomorphic and showed only melting transitions. Beilstein J. Org. Chem. 2... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2973481 Mon, 09 Nov 2009 00:00:00 +0100 2973481 http://www.medworm.com/index.php?rid=2966457&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-62.pdf Abstract The merger of ionic liquid and liquid crystal fields, obtained by using the imidazolium ring as a common element, has allowed us to tailor a new set of materials which associate specific functionalities. These functionalities are consequences of the original properties of the component, ionic liquids, liquid crystals and their association in a single compound. The study of this interesting association led us to elaborate environment-flexible cationic architectures from which mesomorphic properties emerge. Moreover, we have also explored the influence of different anions on the mesomorphic properties. Beilstein J. Org. Chem. 2009, 5, No. 62.  doi:10.3762/bjoc.5.62 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2966457 Fri, 06 Nov 2009 00:00:00 +0100 2966457 http://www.medworm.com/index.php?rid=2966458&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-61.pdf Abstract A three step route to single diastereoisomers of the vicinal trifluoromethyl motif is described. The route starts from either syn- or anti-α,β-epoxy alcohols and takes a direct approach in that each of the three steps introduces a fluorine atom in a regio- and stereo-specific manner. Starting from either the syn- or the anti-α,β-epoxy alcohol, stereospecific reactions generate two separate diastereoisomeric series of this motif. The route is a significant improvement on an earlier six step strategy. Beilstein J. Org. Chem. 2009, 5, No. 61.  doi:10.3762/bjoc.5.61 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2966458 Thu, 05 Nov 2009 00:00:00 +0100 2966458 http://www.medworm.com/index.php?rid=2958246&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-60.pdf Abstract An efficient partial 5-step synthesis of 4′-O-methylquercetin from quercetin in 63% yield is reported. This strategy relies on the selective protection of the catechol group with dichlorodiphenylmethane in diphenyl ether as solvent and on the selective protection of the hydroxyl groups at positions 3 and 7 with chloromethyl ether. Beilstein J. Org. Chem. 2009, 5, No. 60.  doi:10.3762/bjoc.5.60 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2958246 Wed, 04 Nov 2009 00:00:00 +0100 2958246 http://www.medworm.com/index.php?rid=2933965&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-59.pdf Abstract Three novel phenyltelluroalkoxyl functionalized tweezer-like calix[4]arenes 6-8 and two monophenyltelluropropoxyl functionalized calix[4]arenes 10 (cone conformer) and 12 (partial cone conformer) were synthesized and characterized. They are good Ag+-selective ionophores in ion-selective electrodes evaluated by electromotive force measurements of polymer membrane electrodes. The tweezer-like ionophores 6-8 showed excellent extraction ability towards Ag+ and Hg2+. Beilstein J. Org. Chem. 2009, 5, No. 59.  doi:10.3762/bjoc.5.59 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2933965 Wed, 28 Oct 2009 00:00:00 +0100 2933965 http://www.medworm.com/index.php?rid=2919310&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-58.pdf Abstract With the relatively new technique of coaxial electrospinning, composite fibres of poly(vinylpyrrolidone) with the liquid crystal 4-cyano-4’-octylbiphenyl in its smectic phase as core material could be produced. The encapsulation leads to remarkable confinement effects on the liquid crystal, inducing changes in its phase sequence. We conducted a series of experiments to determine the effect of varying the relative flow rates of inner and outer fluid as well as of the applied voltage during electrospinning on these composite fibres. From X-ray diffraction patterns of oriented fibres we could also establish the orientation of the liquid crystal molecules to be parallel to the fibre axis, a result unexpected when considering the viscosity anisotropy of the liquid crystal kept in... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2919310 Thu, 22 Oct 2009 23:00:00 +0100 2919310 http://www.medworm.com/index.php?rid=2911638&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-57.pdf Abstract Tetraphenylenes 2 with eight peripheral gallic esters were prepared in two steps from octamethoxytetraphenylene 1 in 19–72% yield. Investigation of the mesomorphic properties of 2 by DSC, POM and X-ray diffraction revealed that derivatives 2a–d with short alkoxy chain lengths (C5–C8) did not show any mesomorphic properties, whereas compounds 2e–i with C9–C13 chains displayed rectangular columnar mesophases and compounds 2j–l with C14–C16 chains displayed hexagonal columnar mesophases. Furthermore an anomalous odd-even effect of the clearing points of compounds 2e–l versus chain length was detected. Beilstein J. Org. Chem. 2009, 5, No. 57.  doi:10.3762/bjoc.5.57 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2911638 Tue, 20 Oct 2009 23:00:00 +0100 2911638 http://www.medworm.com/index.php?rid=2893752&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-56.pdf Abstract A continuous flow system for the synthesis of enantioenriched diarylmethanols from aldehydes is described. The system uses an amino alcohol-functionalized polystyrene resin as the catalyst, and the arylating agent is conveniently prepared by transmetallation of triarylboroxins with diethylzinc. Beilstein J. Org. Chem. 2009, 5, No. 56.  doi:10.3762/bjoc.5.56 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2893752 Wed, 14 Oct 2009 23:00:00 +0100 2893752 http://www.medworm.com/index.php?rid=2885752&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-55.pdf Abstract With 3,3′-bi[benzo[b]thiophenyl] as starting material, dibenzo[d,d′]benzo[1,2-b;4,3-b′]dithiophene, a [5]heterohelicene, was synthesized efficiently in 60% yield via formylation and McMurry reaction. Cyclopenta[1,2-b:4,3-b′]bis(benzo[d]thiophen)-6-one, another interesting helical ketone, was also prepared in 79% yield via deprotonation and ketonization of 3,3′-bi[benzo[b]thiophenyl]. In addition, the single-crystal structure of dibenzo[d,d′]benzo[1,2-b;4,3-b′]dithiophene and UV–vis spectra of both title compounds are described. Beilstein J. Org. Chem. 2009, 5, No. 55.  doi:10.3762/bjoc.5.55 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2885752 Mon, 12 Oct 2009 23:00:00 +0100 2885752 http://www.medworm.com/index.php?rid=2882439&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-54.pdf Abstract New concepts for the synthesis of metallomesogens have been recently developed in order to use the metal centre as a scaffold for grafting different functionalities and inducing non-conventional shapes and properties in the resulting complexes. Our strategy was based on the synthesis of mesogenic coordination complexes whose molecular architectures are controlled by the modulation of different and tunable molecular motifs: the nature of the metal ion and the surrounding ligands as central unit, the number of flexible chains at the periphery, and the nature of counter-ions in ionic complexes. The appropriate choice of molecular construction motifs allows control at global architectures and induces pre-selected properties from the level of single molecule to supramolecular network, ... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2882439 Sun, 11 Oct 2009 23:00:00 +0100 2882439 http://www.medworm.com/index.php?rid=2875090&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-53.pdf Abstract Iridium-catalyzed asymmetric ring-opening reactions of oxabicyclic alkenes with various aliphatic and aromatic secondary amines are reported for the first time. The reaction gave the corresponding trans-1,2-dihydronaphthalenol derivatives in good yields with moderate enantioselectivities in the presence of 2.5 mol % [Ir(COD)Cl]2 and 5 mol % bisphosphine ligand (S)-p-Tol-BINAP. The trans-configuration of 3f was confirmed by X-ray crystallography. Beilstein J. Org. Chem. 2009, 5, No. 53.  doi:10.3762/bjoc.5.53 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2875090 Thu, 08 Oct 2009 23:00:00 +0100 2875090 http://www.medworm.com/index.php?rid=2889792&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-48.pdf Beilstein J. Org. Chem. 2009, 5, No. 48.  doi:10.3762/bjoc.5.48 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2889792 Wed, 07 Oct 2009 00:00:00 +0100 2889792 http://www.medworm.com/index.php?rid=2868408&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-48.pdf Abstract No abstract Beilstein J. Org. Chem. 2009, 5, No. 48.  doi:10.3762/bjoc.5.48 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2868408 Wed, 07 Oct 2009 00:00:00 +0100 2868408 http://www.medworm.com/index.php?rid=2868407&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-49.pdf Abstract A series of phthalocyanine-C60 dyads 2a–d was synthesized. Key steps in their synthesis are preparation of the low symmetry phthalocyanine intermediate by the statistical condensation of two phthalonitriles, and the final esterification of the fullerene derivative bearing a free COOH group. Structural characterization of the molecules in solution was performed by NMR spectroscopy, UV-vis spectroscopy and cyclic voltammetry. Preliminary studies suggest formation of liquid crystalline (LC) mesophases for some of the prepared dyads. To the best of our knowledge, this is the first example of LC phthalocyanine-C60 dyads. Beilstein J. Org. Chem. 2009, 5, No. 49.  doi:10.3762/bjoc.5.49 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2868407 Wed, 07 Oct 2009 00:00:00 +0100 2868407 http://www.medworm.com/index.php?rid=2868406&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-50.pdf Abstract The addition of a chiral non-racemic dopant to a nematic liquid crystal (LC) has the effect of transferring the molecular chirality to the phase organization and a chiral nematic phase is formed. This molecular chirality amplification in the LC provides a unique possibility for investigating the relationship between molecular structure, intermolecular interactions, and mesoscale organization. It is known that axially chiral or helical-shaped molecules with reduced conformational disorder are good candidates for high helical twisting power derivatives. In particular, biaryl derivatives are known to be efficient chiral inducers in biaryl nematic mesophases. In this paper, we focus on a new series of helicene-like molecules of known absolute configuration. We have integrated choleste... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2868406 Wed, 07 Oct 2009 00:00:00 +0100 2868406 http://www.medworm.com/index.php?rid=2868405&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-51.pdf Abstract An efficient, solvent free method for the N-arylation of imidazole by 1-(dodecyloxy)-4-iodobenzene using Cu(II)-NaY as catalyst and K2CO3 as base is reported. By this synthetic approach, mesomorphic 3-[4-(dodecyloxy)phenyl]-1-methyl-1H-imidazol-3-ium iodide was synthesized in a two-step procedure, and its mesomorphism has been fully investigated by polarised optical microscopy, differential scanning calorimetry and X-ray diffraction. In addition its lamellar crystal structure, electrochemical behaviour and UV (absorption and emission) properties are reported. Beilstein J. Org. Chem. 2009, 5, No. 51.  doi:10.3762/bjoc.5.51 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2868405 Wed, 07 Oct 2009 00:00:00 +0100 2868405 http://www.medworm.com/index.php?rid=2868404&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-52.pdf Abstract Here we present the design and synthesis of novel banana-discotic dimers and banana-bridged discotic dimers. The chemical structures have been characterized by spectral techniques and elemental analysis. The thermal behaviors of the compounds have been investigated by polarizing optical microscopy and differential scanning calorimetry. None of these synthesized compounds exhibit any liquid crystalline property probably because of the incompatibility of the bent-core with the discotic core. Beilstein J. Org. Chem. 2009, 5, No. 52.  doi:10.3762/bjoc.5.52 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2868404 Tue, 06 Oct 2009 23:00:00 +0100 2868404 http://www.medworm.com/index.php?rid=2841907&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-47.pdf Abstract Synthesis of phenanthro[1,2-b]furan-10,11-dione, the core nucleus present in Tanshinone-I is described in 8–10 steps starting from 2-bromo-3,4-dihydro-1-naphthaldehyde. The bromoaldehyde was converted to methyl 2-(2-bromo-1-naphthyl)acetate or 2-(2-bromo-1-naphthyl)acetonitrile following the protocol of functional group transformations. Subsequent Suzuki coupling of this ester/nitrile derivative with furan-2-boronic acid produced [2-(2-furyl)-1-naphthyl]acetic ester/nitrile which on hydrolysis furnished the corresponding acid derivative. Cyclization of the acid followed by oxidation of the phenol, with Fremy’s salt, produced the tetra-cyclic furoquinone, phenanthro[1,2-b]furan-10,11-dione. This method has also been extended for the synthesis of the tricyclic furoquinon... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2841907 Mon, 28 Sep 2009 23:00:00 +0100 2841907 http://www.medworm.com/index.php?rid=2823364&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-46.pdf We describe the utility of a Pd/C-Cu mediated method in the synthesis of 2,5-disubstituted indoles in water via a coupling-cyclization strategy. Further application of this methodology has been demonstrated in the preparation of a target indole derivative via a 7-step process the key step being the Pd/C-mediated coupling reaction. Beilstein J. Org. Chem. 2009, 5, No. 46.  doi:10.3762/bjoc.5.46 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2823364 Tue, 22 Sep 2009 23:00:00 +0100 2823364 http://www.medworm.com/index.php?rid=2868409&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-45.pdf Abstract A 2-diethanolamine boronyl substituted 1,3-diene has been synthesized in high yield and characterized spectroscopically as well as by X-ray crystallography. This diene has then subsequently been used in a number of fast, high yielding Diels–Alder/cross coupling reactions. Beilstein J. Org. Chem. 2009, 5, No. 45.  doi:10.3762/bjoc.5.45 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2868409 Mon, 21 Sep 2009 00:00:00 +0100 2868409 http://www.medworm.com/index.php?rid=2814129&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-45.pdf Abstract A 2-diethanolamine boronyl substituted 1,3-diene has been synthesized in high yield and characterized spectroscopically as well as by X-ray crystallography. This diene has then subsequently been used in a number of fast, high yielding Diels–Alder/cross coupling reactions. Beilstein J. Org. Chem. 2009, 5, No. 45.  doi:10.3762/bjoc.5.45 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2814129 Sun, 20 Sep 2009 23:00:00 +0100 2814129 http://www.medworm.com/index.php?rid=2861840&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-44.pdf Abstract A number of 4-aryl- and 4-alkynyl-substituted 6H-1,2-oxazines 8 and 9 have been prepared in good yields via cross coupling reactions of halogenated precursors 2, which in turn are easily accessible by bromination of 6H-1,2-oxazines 1. Lewis-acid promoted reaction of 1,2-oxazine 9c with 1-hexyne provided alkynyl-substituted pyridine derivative 12 thus demonstrating the potential of this approach for the synthesis of pyridines. Beilstein J. Org. Chem. 2009, 5, No. 44.  doi:10.3762/bjoc.5.44 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2861840 Wed, 16 Sep 2009 00:00:00 +0100 2861840 http://www.medworm.com/index.php?rid=2854901&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-43.pdf Abstract Novel procedures have been developed to condense benzaldehyde effectively with β-amino acid amides to cyclic benzyl aminals. Double carbamate protection of the heterocycle resulted in fully protected chiral β-alanine derivatives. These serve as universal precursors for the asymmetric synthesis of functionalised β2-amino acids containing acid-labile protected side chains. Diastereoselective alkylation of the tetrahydropyrimidinone is followed by a chemoselective two step degradation of the heterocycle to release the free β2-amino acid. In the course of this study, an L-asparagine derivative was condensed with benzaldehyde and subsequently converted to orthogonally protected (R)-β2-homoaspartate. Beilstein J. Org. Chem. 2009, 5, No. 43.  doi:10.37... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2854901 Mon, 14 Sep 2009 00:00:00 +0100 2854901 http://www.medworm.com/index.php?rid=2792677&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-43.pdf Abstract Novel procedures have been developed to condense benzaldehyde effectively with β-amino acid amides to cyclic benzyl aminals. Double carbamate protection of the heterocycle resulted in fully protected chiral β-alanine derivatives. These serve as universal precursors for the asymmetric synthesis of functionalised β2-amino acids containing acid-labile protected side chains. Diastereoselective alkylation of the tetrahydropyrimidinone is followed by a chemoselective two step degradation of the heterocycle to release the free β2-amino acid. In the course of this study, an L-asparagine derivative was condensed with benzaldehyde and subsequently converted to orthogonally protected (R)-β2 homoaspartate. Beilstein J. Org. Chem. 2009, 5, No. 43.  doi:10.37... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2792677 Sun, 13 Sep 2009 23:00:00 +0100 2792677 http://www.medworm.com/index.php?rid=2818857&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-42.pdf Abstract The reactions of benzo[e][2,1]thiazine-4-chloro-3-carbaldehydes 1 and benzo[e][2,1]thiazine-4-chloro-3-carbonitriles 2 with a number of oxidizing and reducing agents are reported. A number of new, highly functionalized benzo[e][2,1]thiazine derivatives having potential biological activity were synthesized and described. Beilstein J. Org. Chem. 2009, 5, No. 42.  doi:10.3762/bjoc.5.42 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2818857 Wed, 02 Sep 2009 00:00:00 +0100 2818857 http://www.medworm.com/index.php?rid=2827471&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-41.pdf Abstract Structural aspects of the binding of inorganic anions such as perchlorate, hydrogen sulfate, and hexafluorosilicate with the proton cage of octaaminocryptand L1, N(CH2CH2NHCH2-p-xylyl-CH2NHCH2CH2)3N), are examined thoroughly. Crystallographic results for a hexaprotonated perchlorate complex of L1, [(H6L1)6+(ClO4−)]5(ClO4−)·11H2O·CH3CN (1), an octaprotonated hydrogen sulfate complex of L1, [(H8L1)8+(HSO4−)]7(HSO4−)·3H2O·CH3OH (2) and an octaprotonated fluorosilicate complex of L1, [(H8L1)8+(HSiF6−)]3(SiF62−)·(HSiF6−)·15H2O (3), show encapsulation of one perchlorate, hydrogen sulfate and hexafluorosilicate, respectively inside the cage of L1 in their protonated states. Further, detailed structural analysis on co... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2827471 Mon, 31 Aug 2009 00:00:00 +0100 2827471 http://www.medworm.com/index.php?rid=2747426&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-41.pdf Abstract Structural aspects of the binding of inorganic anions like perchlorate, hydrogen sulfate, and hexafluorosilicate with proton cage of octaaminocryptand L1, N(CH2CH2NHCH2-p-xylyl-CH2NHCH2CH2)3N), are examined thoroughly. Crystallographic results show that a hexaprotonated perchlorate complex of L1, [(H6L1)6+(ClO4−)]5(ClO4−)·11H2O·CH3CN (1), octaprotonated bisulfate complex of L1, [(H8L1)8+(HSO4−)]7(HSO4−)·3H2O·CH3OH (2) and octaprotonated fluorosilicate complex of L1, [(H8L1)8+(HSiF6−)]3(SiF62−)·(HSiF6−)·15H2O (3), show encapsulation of one perchlorate, hydrogen sulfate and hexafluorosilicate respectively inside the cage of L1 in their protonated states. Further, detailed structural analysis on complex 1 reveals... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2747426 Sun, 30 Aug 2009 23:00:00 +0100 2747426 http://www.medworm.com/index.php?rid=2719056&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-40.pdf Abstract Microfluidic conditions were applied to acid-mediated reactions, namely, glycosylation, reductive opening of the benzylidene acetal groups, and dehydration, which are the keys to the practical synthesis of N-glycans and the immunostimulating natural product, pristane. A distinctly different reactivity from that in conventional batch stirring was found; the vigorous micromixing of the reactants with the concentrated acids is critical especially for the "fast" reactions to be successful. Such a common feature might be due to the integration of all favorable aspects of microfluidic conditions, i.e., efficient mixing, precise temperature control, and the easy handling of the reactive intermediate by controlling the residence time. The microfluidic reactions cited in this rev... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2719056 Thu, 20 Aug 2009 23:00:00 +0100 2719056 http://www.medworm.com/index.php?rid=2799749&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-40.pdf Abstract Microfluidic conditions were applied to acid-mediated reactions, namely, glycosylation, reductive opening of the benzylidene acetal groups, and dehydration, which are the keys to the practical synthesis of N-glycans and the immunostimulating natural product, pristane. A distinctly different reactivity from that in conventional batch stirring was found; the vigorous micromixing of the reactants with the concentrated acids is critical especially for the “fast” reactions to be successful. Such a common feature might be due to the integration of all favorable aspects of microfluidic conditions, i.e., efficient mixing, precise temperature control, and the easy handling of the reactive intermediate by controlling the residence time. The microfluidic reactions cited in this r... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2799749 Thu, 20 Aug 2009 00:00:00 +0100 2799749 http://www.medworm.com/index.php?rid=2690848&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-39.pdf Abstract Dimeric forms of norbornadiene and benzonorbornadiene were synthesized starting with known monobromide derivatives. The Diels–Alder cycloaddition reaction of dimers with TCNE and PTAD was investigated and new norbornenoid polycyclics were obtained. All compounds were characterized properly using NMR spectroscopy. Beilstein J. Org. Chem. 2009, 5, No. 39.  doi:10.3762/bjoc.5.39 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2690848 Tue, 11 Aug 2009 23:00:00 +0100 2690848 http://www.medworm.com/index.php?rid=2670250&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-38.pdf Beilstein J. Org. Chem. 2009, 5, No. 38.  doi:10.3762/bjoc.5.38 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2670250 Tue, 04 Aug 2009 23:00:00 +0100 2670250 http://www.medworm.com/index.php?rid=2644458&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-37.pdf Abstract The synthesis of phosphonate analogues of ribose-1-phosphate and 5-fluoro-5-deoxyribose-1-phosphate is described. Preparation of both the α- and β- phosphonate anomers are reported for the ribose and 5-fluoro-5-deoxyribose series and a synthesis of the corresponding cyclic phostones of each α-ribose is also reported. These compounds have been prepared as tools to probe the details of fluorometabolism in S. cattleya. Beilstein J. Org. Chem. 2009, 5, No. 37.  doi:10.3762/bjoc.5.37 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2644458 Mon, 27 Jul 2009 23:00:00 +0100 2644458 http://www.medworm.com/index.php?rid=2799750&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-37.pdf Abstract The synthesis of phosphonate analogues of ribose-1-phosphate and 5-fluoro-5-deoxyribose-1-phosphate is described. Preparations of both the α- and β-phosphonate anomers are reported for the ribose and 5-fluoro-5-deoxyribose series and a synthesis of the corresponding cyclic phostones of each α-ribose is also reported. These compounds have been prepared as tools to probe the details of fluorometabolism in S. cattleya. Beilstein J. Org. Chem. 2009, 5, No. 37.  doi:10.3762/bjoc.5.37 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2799750 Mon, 27 Jul 2009 00:00:00 +0100 2799750 http://www.medworm.com/index.php?rid=2761167&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-36.pdf Abstract Ten dipyridodiazepinone derivatives were synthesized and evaluated for their anti HIV-1 reverse transcriptase activity against wild-type and mutant type enzymes, K103N and Y181C. Two of them were found to be promising inhibitors for HIV-1 RT. Beilstein J. Org. Chem. 2009, 5, No. 36.  doi:10.3762/bjoc.5.36 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2761167 Wed, 22 Jul 2009 00:00:00 +0100 2761167 http://www.medworm.com/index.php?rid=2751002&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-35.pdf Abstract Methodology has been developed for laying down a thin gold-on-silver film on the inner surface of glass capillaries for the purpose of catalysing benzannulation reactions. The cycloaddition precursors are flowed through these capillaries while the metal film is being heated to high temperatures using microwave irradiation. The transformation can be optimized rapidly, tolerates a wide number of functional groups, is highly regioselective, and proceeds in good to excellent conversion. Beilstein J. Org. Chem. 2009, 5, No. 35.  doi:10.3762/bjoc.5.35 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2751002 Tue, 21 Jul 2009 00:00:00 +0100 2751002 http://www.medworm.com/index.php?rid=2620269&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-35.pdf Abstract Methodology has been developed for laying down a thin gold-on-silver film on the inner surface of glass capillaries for the purpose of catalysing benzannulation reactions. The cycloaddition precursors are flowed through these capillaries while the metal film is being heated to high temperatures using microwave irradiation. The transformation can be optimized rapidly, tolerates a wide number of functional groups, is highly regioselective, and proceeds in good to excellent conversion. Beilstein J. Org. Chem. 2009, 5, No. 35.  doi:10.3762/bjoc.5.35 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2620269 Mon, 20 Jul 2009 23:00:00 +0100 2620269 http://www.medworm.com/index.php?rid=2597466&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-34.pdf Abstract Radical-based carbonylation reactions of alkyl halides were conducted in a microflow reactor under pressurized carbon monoxide gas. Good to excellent yields of carbonylated products were obtained via radical formylation, carbonylative cyclization and three-component coupling reactions, using tributyltin hydride or TTMSS as a radical mediator. Beilstein J. Org. Chem. 2009, 5, No. 34.  doi:10.3762/bjoc.5.34 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2597466 Mon, 13 Jul 2009 23:00:00 +0100 2597466 http://www.medworm.com/index.php?rid=2666694&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-33.pdf Abstract Mitomycins are a class of very potent antibacterial and anti-cancer compounds having a broad activity against a range of tumours. They have been used in clinics since the 1960’s, and the challenges represented by their total synthesis have challenged generations of chemists. Despite these chemical and medicinal features, these compounds, in racemic form, have succumbed to total synthesis only four times over the last 30 years. Beilstein J. Org. Chem. 2009, 5, No. 33.  doi:10.3762/bjoc.5.33 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2666694 Wed, 08 Jul 2009 00:00:00 +0100 2666694 http://www.medworm.com/index.php?rid=2579554&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-33.pdf Abstract Mitomycins are a class of very potent antibacterial and anti-cancer compounds having a broad activity against a range of tumours. They have been used in clinic since the 1960’s. These special biological features and the challenges represented by their total synthesis have challenged generations of chemists. Despite these chemical and medicinal features, these compounds, in racemic form, have succumbed to total synthesis only four times over the last 30 years. Beilstein J. Org. Chem. 2009, 5, No. 33.  doi:10.3762/bjoc.5.33 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2579554 Tue, 07 Jul 2009 23:00:00 +0100 2579554 http://www.medworm.com/index.php?rid=2600812&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-32.pdf Abstract A two step synthesis of 2-alkynyl-4-arylquinolines has been accomplished via Pd/C-mediated regioselective C-2 alkynylation of 2,4-dichloroquinoline in water followed by Suzuki coupling at C-4 of the resulting 4-chloro derivative. Beilstein J. Org. Chem. 2009, 5, No. 32.  doi:10.3762/bjoc.5.32 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2600812 Wed, 01 Jul 2009 00:00:00 +0100 2600812 http://www.medworm.com/index.php?rid=2555362&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-31.pdf Abstract Treatment of benzanthrone (1) with biphenyl-2-yl lithium leads to the surprisingly stable enol 4, which is converted by dehydrogenation into the benzanthrone derivative 7. Under acidic conditions 4 isomerises to the spiro compound 11 and the bicyclo[4.3.1]decane derivative 12. Furthermore, the formation of 7 and the hydrogenated compound 13 is observed. A mechanism for the formation of the reaction products is proposed and supported by DFT calculations. Beilstein J. Org. Chem. 2009, 5, No. 31.  doi:10.3762/bjoc.5.31 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2555362 Mon, 29 Jun 2009 23:00:00 +0100 2555362 http://www.medworm.com/index.php?rid=2552391&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-30.pdf Abstract Aromatic aldehydes have been converted into the corresponding carbamoyl azides using iodine azide. These reactions have been performed safely under continuous flow reaction conditions in microreactors. Beilstein J. Org. Chem. 2009, 5, No. 30.  doi:10.3762/bjoc.5.30 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2552391 Fri, 12 Jun 2009 00:00:00 +0100 2552391 http://www.medworm.com/index.php?rid=2467654&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-29.pdf Abstract A continuous flow parallel reactor system has been developed to provide a rapid and seamless transition from the discovery phase and production phase of chemical synthesis, particularly in low volume-high value pharmaceuticals production. Using a single fixed bed catalytic meso reactor, reactions can be screened on a small discovery scale over short time scales. The intensified process produces sufficient material for a full analysis. By replication of the single reactor in parallel, the same chemistry can be achieved on a larger scale, on a small footprint and without the mass and heat transport limitations of reactor scale-out in batch. Beilstein J. Org. Chem. 2009, 5, No. 29.  doi:10.3762/bjoc.5.29 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2467654 Wed, 10 Jun 2009 02:08:21 +0100 2467654 http://www.medworm.com/index.php?rid=2455417&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-28.pdf Abstract Highly potent and selective inhibitors of neuronal nitric oxide synthase (nNOS) possessing a 2-aminopyridine group were recently designed and synthesized in our laboratory and were shown to have significant in vivo efficacy. In this work, analogs of our lead compound possessing 2- and 4-aminothiazole rings in place of the aminopyridine were synthesized. The less basic aminothiazole rings will be less protonated at physiological pH than the aminopyridine ring, and so the molecule will carry a lower net charge. This could lead to an increased ability to cross the blood-brain barrier thereby increasing the in vivo potency of these compounds. The 2-aminothiazole-based compound was less potent than the 2-aminopyridine-based analogue. 4-Aminothiazoles were unstable in water, undergoing ... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2455417 Fri, 05 Jun 2009 04:00:00 +0100 2455417 http://www.medworm.com/index.php?rid=2520829&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-28.pdf Abstract Highly potent and selective inhibitors of neuronal nitric oxide synthase (nNOS) possessing a 2-aminopyridine group were recently designed and synthesized in our laboratory and were shown to have significant in vivo efficacy. In this work, analogs of our lead compound possessing 2- and 4-aminothiazole rings in place of the aminopyridine were synthesized. The less basic aminothiazole rings will be less protonated at physiological pH than the aminopyridine ring, and so the molecule will carry a lower net charge. This could lead to an increased ability to cross the blood-brain barrier thereby increasing the in vivo potency of these compounds. The 2-aminothiazole-based compound was less potent than the 2-aminopyridine-based analogue. 4-Aminothiazoles were unstable in water, undergoing ... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2520829 Thu, 04 Jun 2009 00:00:00 +0100 2520829 http://www.medworm.com/index.php?rid=2520830&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-27.pdf We report the use of an immobilised form of Candida antarctica lipase B, Novozym® 435, in a preliminary investigation into the development of a continuous flow reactor capable of performing the chemo-enzymatic oxidation of alkenes in high yield and purity, utilising the commercially available oxidant hydrogen peroxide (100 volumes). Initial investigations focussed on the lipase-mediated oxidation of 1-methylcyclohexene, with the optimised reaction conditions subsequently employed for the epoxidation of an array of aromatic and aliphatic alkenes in 97.6 to 99.5% yield and quantitative purity. Beilstein J. Org. Chem. 2009, 5, No. 27.  doi:10.3762/bjoc.5.27 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2520830 Tue, 02 Jun 2009 00:00:00 +0100 2520830 http://www.medworm.com/index.php?rid=2455418&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-27.pdf We report the use of an immobilised form of Candida antarctica lipase B, Novozym® 435, in a preliminary investigation into the development of a continuous flow reactor capable of performing the chemo-enzymatic oxidation of alkenes in high yield and purity, utilising the commercially available oxidant hydrogen peroxide (100 volumes). Initial investigations focussed on the lipase-mediated oxidation of 1-methylcyclohexene, with the optimised reaction conditions subsequently employed for the epoxidation of an array of aromatic and aliphatic alkenes in 97.6 to 99.5% yield and quantitative purity. Beilstein J. Org. Chem. 2009, 5, No. 27.  doi:10.3762/bjoc.5.27 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2455418 Tue, 02 Jun 2009 00:00:00 +0100 2455418 http://www.medworm.com/index.php?rid=2439527&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-26.pdf Abstract Flavin chromophores can mediate redox reactions upon irradiation by blue light. In an attempt to increase their catalytic efficacy, flavin derivatives bearing a guanidinium ion as oxoanion binding site were prepared. Chromophore and substrate binding site are linked by a rigid Kemp's acid structure. The molecular structure of the new flavins was confirmed by an X-ray structure analysis and their photocatalytic activity was investigated in benzyl ester cleavage, nitroarene reduction and a Diels–Alder reaction. The modified flavins photocatalyze the reactions, but the introduced substrate binding site does not enhance their performance. Beilstein J. Org. Chem. 2009, 5, No. 26.  doi:10.3762/bjoc.5.26 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2439527 Fri, 29 May 2009 01:25:58 +0100 2439527 http://www.medworm.com/index.php?rid=2520831&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-26.pdf Abstract Flavin chromophores can mediate redox reactions upon irradiation by blue light. In an attempt to increase their catalytic efficacy, flavin derivatives bearing a guanidinium ion as oxoanion binding site were prepared. Chromophore and substrate binding site are linked by a rigid Kemp’s acid structure. The molecular structure of the new flavins was confirmed by an X-ray structure analysis and their photocatalytic activity was investigated in benzyl ester cleavage, nitroarene reduction and a Diels–Alder reaction. The modified flavins photocatalyze the reactions, but the introduced substrate binding site does not enhance their performance. Beilstein J. Org. Chem. 2009, 5, No. 26.  doi:10.3762/bjoc.5.26 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2520831 Thu, 28 May 2009 00:00:00 +0100 2520831 http://www.medworm.com/index.php?rid=2436022&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-24.pdf Abstract The application of titanium dioxide as an oxidant in tandem oxidation type processes is described. Under microwave irradiation, quinoxalines have been synthesized in good yields from the corresponding α-hydroxyketones. Beilstein J. Org. Chem. 2009, 5, No. 24.  doi:10.3762/bjoc.5.24 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2436022 Wed, 27 May 2009 04:00:00 +0100 2436022 http://www.medworm.com/index.php?rid=2520832&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-25.pdf Abstract Photochromic pyrans for applications in material and life sciences were synthesized via palladium-mediated cyanation, carbonylation and Sonogashira cross-coupling starting from bromo-substituted naphthopyran 1 and benzopyrans 2a/b. A novel photoswitchable benzopyran-based ω-amino acid 6 for Fmoc-based solid-phase peptide synthesis is presented. The photochromic behaviour of the 3-cyano-substituted benzopyran 5a was investigated by time-resolved absorption spectroscopy in the picosecond time domain. Beilstein J. Org. Chem. 2009, 5, No. 25.  doi:10.3762/bjoc.5.25 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2520832 Wed, 27 May 2009 00:00:00 +0100 2520832 http://www.medworm.com/index.php?rid=2520833&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-24.pdf Abstract The application of titanium dioxide as an oxidant in tandem oxidation type processes is described. Under microwave irradiation, quinoxalines have been synthesized in good yields from the corresponding α-hydroxyketones. Beilstein J. Org. Chem. 2009, 5, No. 24.  doi:10.3762/bjoc.5.24 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2520833 Mon, 25 May 2009 00:00:00 +0100 2520833 http://www.medworm.com/index.php?rid=2426782&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-23.pdf Abstract A new synthesis of α-ketoesters using a combination of commercially available mesofluidic flow equipment and tubes packed with immobilised reagents and scavengers is reported. Beilstein J. Org. Chem. 2009, 5, No. 23.  doi:10.3762/bjoc.5.23 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2426782 Thu, 21 May 2009 04:00:00 +0100 2426782 http://www.medworm.com/index.php?rid=2422338&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-22.pdf Abstract The first synthesis of bioactive long alkyl chain 5-n-alkylresorcinols, present in whole grain products, by a novel modification of the Wittig reaction is described. All the main long chain 5-n-alkylresorcinols present in rye and wheat, including C23 and C25 analogues and haptens, which have not been previously prepared, were synthesised. Microwave-promoted reactions of a semi-stabilized ylid and alkanals in water gave good yields in both pressurized and open systems. An alternative microwave-promoted synthesis starting from non-stabilized alkyltriphenylphosphonium salts and 3,5-dimethoxybenzaldehyde worked as well. Aqueous media were suitable for the reactions even if the starting materials were not soluble in water. The 5-n-alkylresorcinols are potential biomarkers of whole grai... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2422338 Wed, 20 May 2009 04:00:00 +0100 2422338 http://www.medworm.com/index.php?rid=2520834&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-23.pdf Abstract Using a combination of commercially available mesofluidic flow equipment and tubes packed with immobilised reagents and scavengers, a new synthesis of α-ketoesters is reported. Beilstein J. Org. Chem. 2009, 5, No. 23.  doi:10.3762/bjoc.5.23 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2520834 Wed, 20 May 2009 00:00:00 +0100 2520834 http://www.medworm.com/index.php?rid=2520835&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-22.pdf Abstract The first synthesis of bioactive long alkyl chain 5-n-alkylresorcinols, present in whole grain products, by a novel modification of the Wittig reaction is described. All the main long chain 5-n-alkylresorcinols present in rye and wheat, including C23 and C25 analogues and haptens, which have not been previously prepared, were synthesised. Microwave-promoted reactions of a semi-stabilized ylid and alkanals in water gave good yields in both pressurized and open systems. An alternative microwave-promoted synthesis starting from non-stabilized alkyltriphenylphosphonium salts and 3,5-dimethoxybenzaldehyde worked as well. Aqueous media were suitable for the reactions even if the starting materials were not soluble in water. The 5-n-alkylresorcinols are potential biomarkers of whole grai... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2520835 Tue, 19 May 2009 00:00:00 +0100 2520835 http://www.medworm.com/index.php?rid=2402215&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-21.pdf Abstract The preparation of monolithic polyionic supports which serve as efficient heterogeneous supports for palladium(0) nanoparticles is described. These functionalized polymers were incorporated inside a flow reactor and employed in Suzuki–Miyaura and Heck cross couplings under continuous flow conditions. Beilstein J. Org. Chem. 2009, 5, No. 21.  doi:10.3762/bjoc.5.21 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2402215 Mon, 11 May 2009 02:41:32 +0100 2402215 http://www.medworm.com/index.php?rid=2396384&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-20.pdf Abstract The title compound, 4,13-bis[(1E,3E)-4-(9-anthracenyl)buta-1,3-dienyl][2.2]paracyclophane (2), prepared in 35% overall yield from [2.2]paracyclophane, absorbs light at λmax = 400 nm with a tail down to 480 nm. By irradiation into this band, 2 generates a single photoproduct, 4, whose absorption maximum is situated at 306 nm. The starting material is recovered by irradiation at 306 nm or by heating. This ‘inverse’ photochromic system has a potential for optical information storage, compound 4 being stable in visible light, at ambient temperature. Beilstein J. Org. Chem. 2009, 5, No. 20.  doi:10.3762/bjoc.5.20 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2396384 Fri, 08 May 2009 01:38:20 +0100 2396384 http://www.medworm.com/index.php?rid=2379753&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-19.pdf Abstract An overview of asymmetric synthesis in continuous flow and microreactors is presented in this review. Applications of homogeneous and heterogeneous asymmetric catalysis as well as biocatalysis in flow are discussed. Beilstein J. Org. Chem. 2009, 5, No. 19.  doi:10.3762/bjoc.5.19 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2379753 Thu, 30 Apr 2009 04:00:00 +0100 2379753 http://www.medworm.com/index.php?rid=2379757&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-15.pdf Beilstein J. Org. Chem. 2009, 5, No. 15.  doi:10.3762/bjoc.5.15 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2379757 Wed, 29 Apr 2009 00:00:00 +0100 2379757 http://www.medworm.com/index.php?rid=2379756&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-16.pdf Abstract A microflow system consisting of micromixers and microtube reactors provides an effective method for the introduction of two electrophiles onto dibromobiaryls. Selective monolithiation of dibromobiaryls, such as 2,2’-dibromobiphenyl, 4,4’-dibromobiphenyl, 2,7-dibromo-9,9-dioctylfluorene, 2,2’-dibromo-1,1’-binaphthyl, and 2,2’-dibromobibenzyl with 1 equiv of n-butyllithium followed by the reaction with electrophiles was achieved using a microflow system by virtue of fast micromixing and precise temperature control. Sequential introduction of two different electrophiles was achieved using an integrated microflow system composed of four micromixers and four microtube reactors to obtain unsymmetrically substituted biaryl compounds. Beilstein J. Org. Chem... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2379756 Wed, 29 Apr 2009 00:00:00 +0100 2379756 http://www.medworm.com/index.php?rid=2379755&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-17.pdf Abstract We demonstrate the preparation and characterization of a simplified packed-bed microreactor using an immobilized TEMPO catalyst shown to oxidize primary and secondary alcohols via the biphasic Anelli-Montanari protocol. Oxidations occurred in high yields with great stability over time. We observed that plugs of aqueous oxidant and organic alcohol entered the reactor as plugs but merged into an emulsion on the packed-bed. The emulsion coalesced into larger plugs upon exiting the reactor, leaving the organic product separate from the aqueous by-products. Furthermore, the microreactor oxidized a wide range of alcohols and remained active in excess of 100 trials without showing any loss of catalytic activity. Beilstein J. Org. Chem. 2009, 5, No. 17.  doi:10.3762/bjoc.5.17 (... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2379755 Wed, 29 Apr 2009 00:00:00 +0100 2379755 http://www.medworm.com/index.php?rid=2379754&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-18.pdf Abstract A miniflow system for oxidative cyclization of alkenols with Oxone was developed. Thus, the oxidative cyclization of (Z)- and (E)-alkenols in i-PrOH with an aqueous solution of Oxone proceeded smoothly and safely in a PTFE tube without any exogenous catalytic species, and was subsequently quenched in a flow-reaction manner to afford the corresponding furanyl and pyranyl carbinols quantitatively within 5 or 10 min of residence time. Beilstein J. Org. Chem. 2009, 5, No. 18.  doi:10.3762/bjoc.5.18 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2379754 Wed, 29 Apr 2009 00:00:00 +0100 2379754 http://www.medworm.com/index.php?rid=2363394&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-14.pdf Abstract A short stereoselective synthesis of (+)-(6R,2'S)-cryptocaryalactone was successfully completed. Key steps included the application of Carreira’s asymmetric alkynylation reaction to form a propargylic alcohol and subsequently lactone formation using the powerful ring-closing metathesis reaction. Beilstein J. Org. Chem. 2009, 5, No. 14.  doi:10.3762/bjoc.5.14 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2363394 Fri, 24 Apr 2009 04:00:00 +0100 2363394 http://www.medworm.com/index.php?rid=2363395&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-13.pdf Abstract The solid-phase synthesis of 4H-3,1-benzoxazin-4-ones was achieved using silica-bound benzoyl chloride (SBBC) as dehydrating agent in reaction with 2-acylaminobenzoic acids. The silica-grafted reagent (SBBC) was simply recovered after reaction and reused several times. Beilstein J. Org. Chem. 2009, 5, No. 13.  doi:10.3762/bjoc.5.13 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2363395 Thu, 23 Apr 2009 00:00:00 +0100 2363395 http://www.medworm.com/index.php?rid=2339270&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-12.pdf Abstract The synthesis of (−)-complanine, an inflammatory substance of Eurythoe complanata, was accomplished by a “chiral synthon” approach. The absolute configuration of this molecule was determined to be R. Beilstein J. Org. Chem. 2009, 5, No. 12.  doi:10.3762/bjoc.5.12 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2339270 Sat, 18 Apr 2009 04:00:00 +0100 2339270 http://www.medworm.com/index.php?rid=2339271&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-11.pdf Abstract Simple, straightforward and optimized procedures for preparing extended π-conjugated linkers are described. Either unsubstituted or 4-donor substituted π-linkers bearing a styryl, biphenyl, phenylethenylphenyl, and phenylethynylphenyl π-conjugated backbone are functionalized with boronic pinacol esters as well as with terminal acetylene moieties allowing their further use as building blocks in Suzuki–Miyaura or Sonogashira coupling reactions. Beilstein J. Org. Chem. 2009, 5, No. 11.  doi:10.3762/bjoc.5.11 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2339271 Tue, 14 Apr 2009 00:00:00 +0100 2339271 http://www.medworm.com/index.php?rid=2324486&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fpdf%2F1860-5397-5-10.pdf Abstract The N-acylation of ethanolamine (2) with various fatty acids 1a–d and esters of fatty acids 1e–h using Candida antarctica B lipase (Novozym® 435) are described and optimum conditions for selective N-acylation rather than O-acylation are also discussed. Microwave assisted solution phase, solid supported and conventional methods were investigated and results were compared. There is a synergy between the enzyme catalysis and microwave irradiation. Beilstein J. Org. Chem. 2009, 5, No. 10.  doi:10.3762/bjoc.5.10 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2324486 Sat, 11 Apr 2009 04:00:00 +0100 2324486 http://www.medworm.com/index.php?rid=2296341&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-10.pdf Abstract The N-acylation of ethanolamine (2) with various fatty acids 1a–d and esters of fatty acids 1e–h using Candida antarctica B lipase (Novozym® 435) are described and optimum conditions for selective N-acylation rather than O-acylation are also discussed. Microwave assisted solution phase, solid supported and conventional methods were investigated and results were compared. There is a synergy between the enzyme catalysis and microwave irradiation Beilstein J. Org. Chem. 2009, 5, No. 10.  doi:10.3762/bjoc.5.10 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2296341 Sun, 29 Mar 2009 04:00:00 +0100 2296341 http://www.medworm.com/index.php?rid=2257108&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-9.pdf Abstract This paper describes a simple route to enantiomerically enriched [2.2]paracyclophane-4-thiol via the stereospecific introduction of a chiral sulfoxide to the [2.2]paracyclophane skeleton. The first synthesis of an enantiomerically enriched planar chiral benzothiazole is also reported. Beilstein J. Org. Chem. 2009, 5, No. 9.  doi:10.3762/bjoc.5.9 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2257108 Fri, 13 Mar 2009 03:05:40 +0100 2257108 http://www.medworm.com/index.php?rid=2226800&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-8.pdf Abstract The reactions of a 5-chloro-2,3-diphenyltetrazolium salt with amines have been examined. In the presence of an inorganic base such as NaHCO3, primary and secondary amines undergo a nucleophilic substitution to give the corresponding 5-aminotetrazolium salts. When triethylamine is used as a base, primary amines give 3-phenylazo-1,2,4-triazoles. A plausible dual-path mechanism is proposed for the formation of the triazoles via Type B mesoionic tetrazolium-5-aminides. Beilstein J. Org. Chem. 2009, 5, No. 8.  doi:10.3762/bjoc.5.8 (Source: Beilstein Journal of Organic Chemistry) Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2226800 Mon, 02 Mar 2009 05:00:00 +0100 2226800 http://www.medworm.com/index.php?rid=2209428&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-7.pdf Abstract A number of diarylmethanofullerene derivatives were synthesized. The cyclopropane ring of the derivatives has two aryl groups substituted with electron-withdrawing and -donating groups, the latter with long alkyl chains to improve solubility in organic solvents, an important property in processing cells. First reduction potentials of most derivatives were less negative than that of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), which is possibly ascribed to their electron-withdrawing nature. Organic thin-film photovoltaic cells fabricated with poly(3-hexylthiophene) (P3HT) as the electron-donor and diarylmethanofullerene derivatives as the electron-acceptor material were examined. The {(methoxycarbonyl)phenyl[bis(octyloxy)phenyl]methano}fullerene showed power conversion effici... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2209428 Tue, 24 Feb 2009 05:00:00 +0100 2209428 http://www.medworm.com/index.php?rid=2199783&cid=s_34014_59_f&fid=34014&url=http%3A%2F%2Fwww.beilstein-journals.org%2Fbjoc%2Fcontent%2Fprovisional%2F1860-5397-5-6.pdf Abstract A number of new ferrocene-π-extended-dithiafulvalenes were successfully synthesized as new electron donor compounds. The chemical structures and electrochemical behaviors of these compounds were investigated using several spectroscopic methods. The synthesis of these compounds was achieved using the modified Wittig–Horner cross-coupling reaction using n BuLi/THF at temperature varies from −78 °C to 0 °C. These new classes of bis(1,3-dithiafulvalene)ferrocenes have the 1,3-dithiole ring system separated by ferrocene as conjugated spacer. The ferrocene-dithiafulvalenes derivatives 9 and 12 were prepared as side products during the synthesis of the targeted compounds as bis(1,3-dithiafulvalene)ferrocenes 8, 10 and 11 in variable yields. The redox properties... Beilstein Journal of Organic Chemistry journals http://www.medworm.com/rss/comments.php?id=2199783 Fri, 20 Feb 2009 05:00:00 +0100 2199783