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Total 408186 results found since Jan 2013.

Regioselectivity of the SEAr-based cyclizations and SEAr-terminated annulations of 3,5-unsubstituted, 4-substituted indoles
Abstract Indole-3,4- and 4,5-fused carbo- and heterocycles are ubiquitous in bioactive natural products and pharmaceuticals, and hence, a variety of synthetic approaches toward such compounds have been developed. Among these, cyclization and annulation of 3,5-unsubstituted, 4-substituted indoles involving an electrophilic aromatic substitution (SEAr) as the ring closure are particularly attractive, because they avoid the use of 3,4- or 4,5-difunctionalized indoles as starting materials. However, since 3,5-unsubstituted, 4-substituted indoles have two potential ring-closure sites (indole C3 and C5 positions), such reactions...
Source: Beilstein Journal of Organic Chemistry - March 8, 2022 Category: Chemistry Authors: Beilstein Journal of Organic Chemistry - Syndicated Feeds Tags: annulation cyclization fused indoles regioselectivity SEAr Commentary Source Type: research

Step-by-Step Multifunctionalization of Isoxazoles Based On SEAr Reactions and C –H Direct Arylations
Synthesis DOI: 10.1055/s-0036-1588784 Functionalized isoxazoles are important as pharmaceuticals and agrochemicals. Generally, electrophilic aromatic substitution or generation of carbanions/electrophilic trapping approach is used to introduce functional groups into unsubstituted heteroaromatics. However, these approaches have not been simple to apply to unsubstituted isoxazoles due to their poor nucleophilicity and instability under basic conditions. Recently several approaches have been reported to overcome these problems. This review summarizes the functionalization of isoxazoles, including SEAr reactions and C–H dire...
Source: Synthesis - April 18, 2017 Category: Chemistry Authors: Fuse, Shinichiro Morita, Taiki Nakamura, Hiroyuki Tags: short review Source Type: research

Intramolecular SEAr of phosphorus derivatives: computational approach to the synthesis of π-extended heterocycles.
Abstract The reaction mechanism associated with the synthesis of phosphorus-based heteropolyaromatic architectures by intramolecular SEAr have been investigated by DFT calculations at the B3LYP-D3/6-311+G(D) level of theory. The purpose of this study is to provide essential information for the future development of improved polycyclic organophosphorus materials. To that end, we have studied the impact of the initial reactant and/or the intermediates' structure into the mechanistic features and energetic profiles of the phosphorus cyclization process. Moreover, we have analysed in detail the reactivity parameters w...
Source: Chemistry - September 18, 2017 Category: Chemistry Authors: Larrañaga O, Romero-Nieto C, de Cozar Ruano A Tags: Chemistry Source Type: research

Formation of Unexpectedly Active Ni-Fe Oxygen Evolution Electrocatalysts by Physically Mixing Ni and Fe Oxyhydroxides
This article is licensed under aCreative Commons Attribution-NonCommercial 3.0 Unported Licence.Mikaela Gorlin, Petko Chernev, Paul Paciok, Cheuk-Wai Tai, Jorge Ferreira de Araujo, Tobias Reier, Marc Heggen, R Dunin-Borkowski, Peter Strasser, Holger Dau We present an unusual, yet facile, strategy towards formation of physically mixed Ni-Fe(OxHy) oxygen evolution electrocatalysts. We use in situ X-ray absorption and UV-vis spectroscopy, and high-resolution imaging to demonstrate... The content of this RSS Feed (c) The Royal Society of Chemistry
Source: RSC - Chem. Commun. latest articles - December 12, 2018 Category: Chemistry Authors: Mikaela Gorlin Source Type: research

A review on possible mechanisms of sonocrystallisation in solution.
Abstract Sonocrystallisation is the application of ultrasound to the crystallisation process. The benefits obtained by sonication have been widely studied since the beginning of the 20th century and so far it is clear that ultrasound can be a very useful tool for enhancing crystallisation and controlling the properties of the final product. Crystal size, polymorphs, purity, process repeatability and lower induction time are only some of the advantages of sonocrystallisation. Even though the effects of sonication on crystallisation are quite clear, the physical explanation of the phenomena involved is still lacking...
Source: Ultrasonics Sonochemistry - June 20, 2019 Category: Chemistry Authors: Nalesso S, Bussemaker MJ, Sear RP, Hodnett M, Lee J Tags: Ultrason Sonochem Source Type: research

Structure-activity relationship study of cytotoxic neolignan derivatives using multivariate analysis and computation-aided drug design.
Abstract Dehydrodieugenol B and five related natural neolignans were isolated from the Brazilian plant species Nectandra leucantha. Three of these compounds were shown to be active against murine (B16F10) and human (A2058) melanoma cells but non-toxic to human fibroblasts (T75). These results stimulated the preparation of a series of 23 semi-synthetic derivatives in order to explore structure-activity relationships and study the biological potential of these derivatives against B16F10 and A2058 cell lines. These structurally-related neolignan derivatives were analyzed by multivariate statistics and machine learnin...
Source: Bioorganic and Medicinal Chemistry Letters - July 8, 2020 Category: Chemistry Authors: de Sousa FS, Baldim JL, Azevedo RA, Figueiredo CR, Pieper P, Sear CE, Anderson EA, Lago JHG Tags: Bioorg Med Chem Lett Source Type: research

Quantitative Studies of Crystal Nucleation at Constant Supersaturation: Experimental Data and Models
CrystEngComm, 2014, Accepted ManuscriptDOI: 10.1039/C4CE00344F, HighlightRichard SearCrystallisation starts off with nucleation, which is rather poorly understood. However, over the last few years there have been important quantitative experiments at constant supersaturation, and the modelling of this...The content of this RSS Feed (c) The Royal Society of Chemistry
Source: RSC - CrystEngComm latest articles - May 27, 2014 Category: Chemistry Authors: Richard Sear Source Type: research

Sonocrystallisation of ZIF-8 in water with high excess of ligand: Effects of frequency, power and sonication time
Ultrason Sonochem. 2021 Jun 6;76:105616. doi: 10.1016/j.ultsonch.2021.105616. Online ahead of print.ABSTRACTA systematic study on the sonocrystallisation of ZIF-8 (zeolitic imidazolate framework-8) in a water-based system was investigated under different mixing speeds, ultrasound frequencies, calorimetric powers and sonication time. Regardless of the synthesis technique, pure crystals of ZIF-8 with high BET (Brunauer, Emmett and Teller) specific surface area (SSA) can be obtained in water after only 5 s. Furthermore, 5 s sonication produced even smaller crystals (~0.08 µm). The type of technique applied for producing the ...
Source: Ultrasonics Sonochemistry - June 19, 2021 Category: Chemistry Authors: Silvia Nalesso Gaelle Varlet Madeleine J Bussemaker Richard P Sear Mark Hodnett Rebeca Monteagudo-Oliv án Victor Sebasti án Joaqu ín Coronas Judy Lee Source Type: research

INFERYS Rescoring: boosting peptide identifications and scoring confidence of database search results
Rapid Commun Mass Spectrom. 2021 May 20:e9128. doi: 10.1002/rcm.9128. Online ahead of print.ABSTRACTDatabase search engines for bottom-up proteomics largely ignore peptide fragment ion intensities during the automated scoring of tandem mass spectra against protein databases. Recent advances in deep learning allow the accurate prediction of peptide fragment ion intensities. Using these predictions to calculate additional intensity-based scores help to overcome this drawback. Here, we describe a processing workflow termed INFERYS™ Rescoring for the intensity-based rescoring of Sequest HT search engine results in Thermo Sci...
Source: Rapid Communications in Mass Spectrometry : RCM - May 20, 2021 Category: Chemistry Authors: Daniel P Zolg Siegfried Gessulat Carmen Paschke Michael Graber Magnus Rathke-Kuhnert Florian Seefried Kai Fitzemeier Frank Berg Daniel Lopez-Ferrer David Horn Christoph Henrich Andreas Huhmer Bernard Delanghe Martin Frejno Source Type: research

Understanding the Target Search by Multiple Transcription Factors on Nucleosomal DNA
In this study, by developing a theoretical model based on a discrete-state stochastic approach, we investigated the target search mechanism of multiple TFs on nucleosomal DNA. Experimental kinetic rate constants of different TFs are taken as input to estimate the Mean-First-Passage time to recognize the binding motifs by two TFs on a dynamic nucleosome model. The theory systematically analyzes when the TFs search their binding motifs hierarchically and when simultaneously by proceeding via the formation of a protein-protein complex. Our results, validated by extensive Monte Carlo simulations, elucidate the molecular basis ...
Source: Chemphyschem - January 5, 2023 Category: Chemistry Authors: Sujeet Kumar Mishra Arnab Bhattacherjee Source Type: research