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Hydroxyapatite supported caesium carbonate as a new recyclable solid base catalyst for the Knoevenagel condensation in waterEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - November 20, 2009 Category: Chemistry Authors: Beilstein Journal of Organic Chemistry - Syndicated Feeds Tags: ethyl cyanoacetate hydroxyapatite supported caesium carbonate Knoevenagel condensation malonic acid malononitrile Full Research Paper Source Type: journals

Can we measure catalyst efficiency in asymmetric chemical reactions? A theoretical approachEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 A...
Source: Beilstein Journal of Organic Chemistry - November 19, 2009 Category: Chemistry Authors: Beilstein Journal of Organic Chemistry - Syndicated Feeds Tags: asymmetric catalysis enzymes organocatalysis transition metal complexes Commentary Source Type: journals

An expedient and new synthesis of pyrrolo[1,2-b]pyridazine derivativesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - November 17, 2009 Category: Chemistry Authors: Beilstein Journal of Organic Chemistry - Syndicated Feeds Tags: 1,4-diketone migration and cyclization pyrrolo[1,2-b]pyridazine tertiary butyl carbamate tertiary butyl carbazate α β -unsaturated ketone Full Research Paper Source Type: journals

Molecular length distribution and the formation of smectic phasesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 ...
Source: Beilstein Journal of Organic Chemistry - November 13, 2009 Category: Chemistry Authors: Beilstein Journal of Organic Chemistry - Syndicated Feeds Tags: bidispersity liquid crystals phase diagrams smectic phases structure and dynamics Full Research Paper Source Type: journals

Pd/C-mediated synthesis of α-pyrone fused with a five-membered nitrogen heteroaryl ring: A new route to pyrano[4,3-c]pyrazol-4(1H)-onesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - November 11, 2009 Category: Chemistry Authors: Beilstein Journal of Organic Chemistry - Syndicated Feeds Tags: C – C bond catalysis palladium pyrazole pyrone Preliminary Communication Source Type: journals

Influence of spacer chain lengths and polar terminal groups on the mesomorphic properties of tethered 5-phenylpyrimidinesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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...
Source: Beilstein Journal of Organic Chemistry - November 9, 2009 Category: Chemistry Authors: Beilstein Journal of Organic Chemistry - Syndicated Feeds Tags: calamitic liquid crystals 5-phenylpyrimidines Full Research Paper Source Type: journals

1-(4-alkyloxybenzyl)-3-methyl-1H-imidazol-3-ium organic backbone: A versatile smectogenic moietyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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....
Source: Beilstein Journal of Organic Chemistry - November 6, 2009 Category: Chemistry Authors: Beilstein Journal of Organic Chemistry - Syndicated Feeds Tags: crystal liquid imidazolium salts ionic liquid supramolecular arrangement Full Research Paper Source Type: journals

Three step synthesis of single diastereoisomers of the vicinal trifluoro motifEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 Jo...
Source: Beilstein Journal of Organic Chemistry - November 5, 2009 Category: Chemistry Authors: Beilstein Journal of Organic Chemistry - Syndicated Feeds Tags: C – F bond organo fluorine chemistry stereospecific fluorination vicinal trifluoro motif Full Research Paper Source Type: journals

An efficient partial synthesis of 4′-O-methylquercetin via regioselective protection and alkylation of quercetinEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - November 4, 2009 Category: Chemistry Authors: Beilstein Journal of Organic Chemistry - Syndicated Feeds Tags: alkylation high yield 4 ′ -O-methylquercetin partial synthesis regioselective protection Full Research Paper Source Type: journals

Synthesis and properties of calix[4]arene telluropodant ethers as Ag+ selective sensors and Ag+, Hg2+ extractantsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - October 28, 2009 Category: Chemistry Authors: Yang Lu, Yuanyuan Li, Song He, Yan Lu, Changying Liu, Xianshun Zeng and Langxing Chen Tags: calix[4]arenes extractants mercury sensors silver telluropodant ether Full Research Paper Source Type: journals

Coaxial electrospinning of liquid crystal-containing poly(vinylpyrrolidone) microfibersEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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...
Source: Beilstein Journal of Organic Chemistry - October 22, 2009 Category: Chemistry Authors: Eva Enz, Ute Baumeister and Jan P F Lagerwall Tags: coaxial electrospinning composite material core-sheath fibres liquid crystal smectic phase Full Research Paper Source Type: journals

Saddle-shaped tetraphenylenes with peripheral gallic esters displaying columnar mesophasesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 v...
Source: Beilstein Journal of Organic Chemistry - October 20, 2009 Category: Chemistry Authors: Eugen Wuckert, Constanze Hägele, Frank Giesselmann, Angelika Baro and Sabine Laschat Tags: columnar mesophases discotic liquid crystals tetraphenylene Full Research Paper Source Type: journals

Continuous flow enantioselective arylation of aldehydes with ArZnEt using triarylboroxins as the ultimate source of aryl groupsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - October 14, 2009 Category: Chemistry Authors: Julien Rolland, Xacobe C Cambeiro, Carles Rodríguez-Escrich and Miquel A Pericàs Tags: asymmetric synthesis continuous flow diarylmethanols solid-supported catalyst triarylboroxins Full Research Paper Source Type: journals

The efficient synthesis of dibenzo[d,d’]benzo[1,2-b:4,3-b’]dithiophene and cyclopenta[1,2-b:4,3-b’]bis(benzo[d]thiophen)-6-oneEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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. 5...
Source: Beilstein Journal of Organic Chemistry - October 12, 2009 Category: Chemistry Authors: Hua Wang, Zhihua Wang, Sheng Zhu and Jianwu Shi Tags: crystal structure cyclopenta[1,2-b:4,3-b ’ ]bis(benzo[d]thiophen)-6-one dibenzo[d,d ]benzo[1,2-b;4,3-b ]dithiophene McMurry reaction preparation Full Research Paper Source Type: journals

Functional properties of metallomesogens modulated by molecular and supramolecular exotic arrangementsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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...
Source: Beilstein Journal of Organic Chemistry - October 11, 2009 Category: Chemistry Authors: Alessandra Crispini, Mauro Ghedini and Daniela Pucci Tags: coordination complexes functionality liquid crystals metallomesogens Review Source Type: journals

Iridium-catalyzed asymmetric ring-opening reactions of oxabicyclic alkenes with secondary amine nucleophilesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - October 8, 2009 Category: Chemistry Authors: Dingqiao Yang Tags: chiral bisphosphine ligand iridium catalysis oxabicyclic alkenes ring-opening reaction Full Research Paper Source Type: journals

Progress in liquid crystal chemistryEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Beilstein J. Org. Chem. 2009, 5, No. 48. doi:10.3762/bjoc.5.48 (Source: Beilstein Journal of Organic Chemistry)
Source: Beilstein Journal of Organic Chemistry - October 7, 2009 Category: Chemistry Authors: Sabine Laschat Tags: Editorial Source Type: journals

Progress in liquid crystal chemistryEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract No abstract Beilstein J. Org. Chem. 2009, 5, No. 48. doi:10.3762/bjoc.5.48 (Source: Beilstein Journal of Organic Chemistry)
Source: Beilstein Journal of Organic Chemistry - October 7, 2009 Category: Chemistry Authors: Sabine Laschat Tags: Editorial Source Type: journals

Synthesis of mesogenic phthalocyanine-C60 donor–acceptor dyads designed for molecular heterojunction photovoltaic devicesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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-C6...
Source: Beilstein Journal of Organic Chemistry - October 7, 2009 Category: Chemistry Authors: Yves H Geerts, Olivier Debever, Claire Amato and Sergey Sergeyev Tags: donor – acceptor dyad fullerene liquid crystals phthalocyanine phthalonitrile Full Research Paper Source Type: journals

Chiral amplification in a cyanobiphenyl nematic liquid crystal doped with helicene-like derivativesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 chi...
Source: Beilstein Journal of Organic Chemistry - October 7, 2009 Category: Chemistry Authors: Alberta Ferrarini, Silvia Pieraccini, Stefano Masiero and Gian Piero Spada Tags: chirality cholesteric helical twisting power helicene nematic liquid crystal surface chirality model Full Research Paper Source Type: journals

A convenient method for preparing rigid-core ionic liquid crystalsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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. do...
Source: Beilstein Journal of Organic Chemistry - October 7, 2009 Category: Chemistry Authors: Julien Fouchet, Laurent Douce, Benoît Heinrich, Richard Welter and Alain Louati Tags: imidazolium ionic liquid crystals Ullman reaction. Full Research Paper Source Type: journals

Novel banana-discotic hybrid architecturesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - October 6, 2009 Category: Chemistry Authors: Hari Krishna Bisoyi, H T Srinivasa and Sandeep Kumar Tags: bent-core dimer discotic triphenylene Preliminary Communication Source Type: journals

Studies on polynuclear furoquinones. Part 1: Synthesis of tri- and tetra-cyclic furoquinones simulating BCD/ABCD ring system of furoquinone diterpenoidsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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...
Source: Beilstein Journal of Organic Chemistry - September 28, 2009 Category: Chemistry Authors: Faruk Hasan Shaik and Gandhi Kumar Kar Tags: Fremy ’ s salt oxidation furonaphthoquinone furophenanthraquinone Suzuki reaction Full Research Paper Source Type: journals

Pd/C-Mediated synthesis of indoles in waterEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - September 22, 2009 Category: Chemistry Authors: Mohosin Layek, Udaya Lakshmi, Dipak Kalita, Deepak Kumar Barange, Aminul Islam, K Mukkanti and Manojit Pal Tags: C – C bond charcoal copper indoles palladium Full Research Paper Source Type: journals

Preparation and Diels–Alder/cross coupling reactions of a 2-diethanolaminoboron-substituted 1,3-dieneEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - September 21, 2009 Category: Chemistry Authors: Liqiong Wang, Cynthia S Day, Marcus W Wright and Mark E Welker Tags: cross coupling Diels – Alder organoboron Preliminary Communication Source Type: journals

Preparation and Diels-Alder/cross coupling reactions of a 2-diethanolaminoboron-substituted 1,3-dieneEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - September 20, 2009 Category: Chemistry Authors: Liqiong Wang, Cynthia S Day, Marcus W Wright and Mark E Welker Tags: cross coupling Diels – Alder organoboron Preliminary Communication Source Type: journals

Palladium-catalyzed cross coupling reactions of 4-bromo-6H-1,2-oxazinesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - September 16, 2009 Category: Chemistry Authors: Reinhold Zimmer, Elmar Schmidt, Michal Andrä, Marcel-Antoine Duhs, Igor Linder and Hans-Ulrich Reissig Tags: alkyne halogenation 1,2-oxazines palladium catalysis pyridines Preliminary Communication Source Type: journals

2-Phenyl-tetrahydropyrimidine-4(1H)-ones – cyclic benzaldehyde aminals as precursors for functionalised β2-amino acidsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 ...
Source: Beilstein Journal of Organic Chemistry - September 14, 2009 Category: Chemistry Authors: Markus Nahrwold, Arvydas Stončius, Anna Penner, Beate Neumann, Hans-Georg Stammler and Norbert Sewald Tags: β 2-amino acids cyclocondensation diastereoselective alkylation N,N-acetals peptidomimetics ring opening self-regeneration of stereocentres (SRS) Full Research Paper Source Type: journals

2-Phenyl-tetrahydropyrimidine-4(1H)-ones – cyclic benzaldehyde aminals as precursors for functionalised β2-amino acidsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 ...
Source: Beilstein Journal of Organic Chemistry - September 13, 2009 Category: Chemistry Authors: Markus Nahrwold, Arvydas Stončius, Anna Penner, Beate Neumann, Hans-Georg Stammler and Norbert Sewald Tags: β 2-amino acids cyclocondensation diastereoselective alkylation N,N-acetals peptidomimetics ring opening self-regeneration of stereocentres (SRS) Full Research Paper Source Type: journals

On the functionalization of benzo[e][2,1]thiazineEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - September 2, 2009 Category: Chemistry Authors: Kirill Popov, Tatyana Volovnenko and Julian Volovenko Tags: heterocycles nucleophilic aromatic substitutions oxidation reduction regioselectivity Full Research Paper Source Type: journals

Structural studies on encapsulation of tetrahedral and octahedral anions by a protonated octaaminocryptand cageEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 encapsulati...
Source: Beilstein Journal of Organic Chemistry - August 31, 2009 Category: Chemistry Authors: I Ravikumar, P S Lakshminarayanan, E Suresh and Pradyut Ghosh Tags: anion receptor cryptand molecular recognition proton cage Full Research Paper Source Type: journals

Structural studies on encapsulation of tetrahedral and octahedral anions by a protonated octaaminocryptand cageEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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 perc...
Source: Beilstein Journal of Organic Chemistry - August 30, 2009 Category: Chemistry Authors: I Ravikumar, P S Lakshminarayanan, E Suresh and Pradyut Ghosh Tags: anion receptor cryptand molecular recognition proton cage Full Research Paper Source Type: journals

Acid-mediated reactions under microfluidic conditions: A new strategy for practical synthesis of biofunctional natural productsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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., efficie...
Source: Beilstein Journal of Organic Chemistry - August 20, 2009 Category: Chemistry Authors: Katsunori Tanaka and Koichi Fukase Tags: acid-mediated reaction microreactor natural products synthesis oligosaccharide pristane Review Source Type: journals

Acid-mediated reactions under microfluidic conditions: A new strategy for practical synthesis of biofunctional natural productsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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., effic...
Source: Beilstein Journal of Organic Chemistry - August 20, 2009 Category: Chemistry Authors: Katsunori Tanaka and Koichi Fukase Tags: acid-mediated reaction microreactor natural products synthesis oligosaccharide pristane Review Source Type: journals

Synthesis and Diels–Alder cycloaddition reaction of norbornadiene and benzonorbornadiene dimersEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - August 11, 2009 Category: Chemistry Authors: Bilal Nişancı, Erdin Dalkılıç, Murat Güney and Arif Daştan Tags: benzonorbornadiene Diels – Alder reaction Stille coupling Full Research Paper Source Type: journals

Review of “Stereochemistry Workbook, 191 Problems and Solutions” by K.-H. Hellwich and C. D. SiebertEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Beilstein J. Org. Chem. 2009, 5, No. 38. doi:10.3762/bjoc.5.38 (Source: Beilstein Journal of Organic Chemistry)
Source: Beilstein Journal of Organic Chemistry - August 4, 2009 Category: Chemistry Authors: Roald Hoffmann Tags: Book Report Source Type: journals

Synthesis of phosphonate and phostone analogues of ribose-1-phosphatesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - July 27, 2009 Category: Chemistry Authors: Pitak Nasomjai, David O'Hagan and Alexandra M Z Slawin Tags: 5-fluoro-5-deoxyribose-1-phosphate fluorometabolite biosynthesis phosphonates phostone Full Research Paper Source Type: journals

Synthesis of phosphonate and phostone analogues of ribose-1-phosphatesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - July 27, 2009 Category: Chemistry Authors: Pitak Nasomjai, David O’Hagan and Alexandra M Z Slawin Tags: 5-fluoro-5-deoxyribose-1-phosphate fluorometabolite biosynthesis phosphonates phostone Full Research Paper Source Type: journals

Dipyridodiazepinone derivatives; synthesis and anti HIV-1 activityEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - July 22, 2009 Category: Chemistry Authors: Nisachon Khunnawutmanotham, Nitirat Chimnoi, Arunee Thitithanyanont, Patchreenart Saparpakorn, Kiattawee Choowongkomon, Pornpan Pungpo, Supa Hannongbua and Supanna Techasakul Tags: AIDS anti HIV-1 RT dipyridodiazepinone nevirapine synthesis Full Research Paper Source Type: journals

Gold film-catalysed benzannulation by Microwave-Assisted, Continuous Flow Organic Synthesis (MACOS)Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - July 21, 2009 Category: Chemistry Authors: Gjergji Shore, Michael Tsimerman and Michael G Organ Tags: benzannulation flow synthesis gold catalysis microwave thin metal film Full Research Paper Source Type: journals

Gold film-catalysed benzannulation by Microwave-Assisted, Continuous Flow Organic Synthesis (MACOS).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - July 20, 2009 Category: Chemistry Authors: Michael Organ, Gjergji Shore and Michael Tsimerman Tags: benzannulation flow synthesis gold catalysis microwave thin metal film Full Research Paper Source Type: journals

Radical carbonylations using a continuous microflow systemEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - July 13, 2009 Category: Chemistry Authors: Takahide Fukuyama, Md Taifur Rahman, Naoya Kamata and Ilhyong Ryu Tags: continuous flow system microreactor radical carbonylation radical mediator V-65 Preliminary Communication Source Type: journals

Mitomycins syntheses: a recent updateEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - July 8, 2009 Category: Chemistry Authors: Jean-Christophe Andrez Tags: antitumour bioactivity mitomycin mitosene synthesis Review Source Type: journals

Mitomycins syntheses: a recent updateEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - July 7, 2009 Category: Chemistry Authors: Jean-Christophe Andrez Tags: antitumour, bioactivity, mitomycin, mitosene, synthesis Review Source Type: journals

Regioselective alkynylation followed by Suzuki coupling of 2,4-dichloroquinoline: Synthesis of 2-alkynyl-4-arylquinolinesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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)
Source: Beilstein Journal of Organic Chemistry - July 1, 2009 Category: Chemistry Authors: Ellanki Amarender Reddy, Aminul Islam, K Mukkanti, Venkanna Bandameedi, Dipal Ranjan Bhowmik and Manojit Pal Tags: alkyne boronic acid catalysis 2,4-dichloroquinoline palladium water Preliminary Communication Source Type: journals