Organocatalyzed asymmetric Michael addition by an efficient bifunctional carbohydrate–thiourea hybrid with mechanistic DFT analysis
作者:Chandra S. Azad、Imran A. Khan、Anudeep K. Narula
DOI:10.1039/c6ob02158a
日期:——
core scaffold were synthesized and examined as catalysts for the asymmetricMichael addition reaction of aryl/alkyl trans-β-nitrostyrenes over cyclohexanone and other Michael donors having active methylene. Excellent enantioselectivities (<95%), diastereoselectivities (<99%), and yields (<99%) were attained undersolvent free conditions using 10 mol% of 1d0. The obtained results were explained through
Design, preparation, and studies of a family of new organiccatalysts are presented. The design of the catalysts is inspired by the ability of DNA nucleobases to develop precise and explicit hydrogen bonds. We have shown that this phenomenon can be used to create a useful organiccatalyst that demonstrates a recognition pattern similar to those of common organic substrates. A selected bifunctional
介绍了一系列新型有机催化剂的设计、制备和研究。催化剂的设计灵感来自于 DNA 核碱基发展精确和明确的氢键的能力。我们已经表明,这种现象可用于创建一种有用的有机催化剂,该催化剂显示出类似于常见有机底物的识别模式。基于鸟嘌呤结构的选定双功能催化剂已被证明可催化 1,3-二羰基化合物与各种硝基烯烃的共轭加成,从而以良好的产率和对映选择性提供产品。
Chiral 2-Aminobenzimidazoles as Recoverable Organocatalysts for the Addition of 1,3-Dicarbonyl Compounds to Nitroalkenes<sup>†</sup>
作者:Diana Almaşi、Diego A. Alonso、Enrique Gómez-Bengoa、Carmen Nájera
DOI:10.1021/jo9010552
日期:2009.8.21
ole organocatalysts promote the conjugate addition of a wide variety of 1,3-dicarbonyl compounds such as malonates, ketoesters, and 1,3-diketones to nitroolefins in the presence of TFA as cocatalyst in toluene as solvent at rt or 0 °C. The Michael adducts are obtained in high yield and enantioselectivity, using the chiral 2-aminobenzimidazole 7b as hydrogen-bond-mediated chiral organocatalyst. This
Organocatalytic enantioselective conjugate addition of nitromethane to alkylidenemalonates: asymmetric synthesis of pyrrolidine-3-carboxylic acid derivatives
作者:Saumen Hajra、Sk Mohammad Aziz、Rajat Maji
DOI:10.1039/c3ra42014k
日期:——
A highlyenantioselectivenitromethaneaddition to alkylidene malonates catalyzed by cinchona-alkaloid derived thiourea based organocatalyst has been developed that offers a new route to the synthesis of substituted pyrrolidine-3-carboxylic acid derivatives and 3-arylpyrrolidines/pyrrolidones.
High‐Pressure‐Mediated Thiourea‐Organocatalyzed Asymmetric Michael Addition to (Hetero)aromatic Nitroolefins: Prediction of Reaction Parameters by PCP‐SAFT Modelling
作者:Thomas Weinbender、Michael Knierbein、Lukas Bittorf、Christoph Held、Riko Siewert、Sergey P. Verevkin、Gabriele Sadowski、Oliver Reiser
DOI:10.1002/cplu.202000364
日期:2020.6
Thiourea‐organocatalyzed Michael additions of diethyl malonate to various heteroaromatic nitroolefins (13 examples) have been studied under high‐pressure (up to 800 MPa) and ambient pressure conditions. High pressure was conducive to enhanced product yields by a factor of 2–12 at a given reaction time, high reaction rates (reaction times were decreased from 72–24 h down to 4–24 h) and high enantioselectivity