Iridium‐catalyzedasymmetrichydrogenation of prochiral halogenated ketones was successfully developed to prepare various chiral halohydrins with high reactivities and excellent enantioselectivities under basic reaction condition (up to >99% conversion, 99% yield, >99% ee). Moreover, gram‐scale experiment was performed well in the presence of just 0.005 mol% (S/C=20 000) Ir/f‐amphox catalyst with 99%
The Ir-Catalyzed Asymmetric Hydrogenation of α-Halogenated Ketones Utilizing Cinchona-Alkaloid-Derived NNP Ligand to Produce (<i>R</i>)- and (<i>S</i>)-Halohydrins
作者:Qian Chen、Hao Sun、Linlin Li、Jie Tian、Qian Xu、Nana Ma、Li Li、Lin Zhang、Chun Li
DOI:10.1021/acs.joc.2c02109
日期:2022.12.2
hydrogenation of α-halogenated ketones with iridium catalyst was developed, utilizing easily accessed cinchona-alkaloid-based NNP ligands. Various α-chloroacetophenones, heterocyclic thienyl and furanyl substrates, and even bromoketones were completely converted to the desired chiral halohydrins by this protocol. Both (R)- and (S)-chiral halohydrins can be prepared by changing the configurations of the chiral
利用易于获取的基于金鸡纳生物碱的 NNP 配体,开发了铱催化剂对 α-卤化酮的不对称氢化。通过该协议,各种 α-氯苯乙酮、杂环噻吩基和呋喃基底物,甚至溴酮完全转化为所需的手性卤代醇。( R )- 和 ( S )- 手性卤代醇都可以通过改变手性配体 NNP 的构型来制备,分别具有高达 99.6% ee(对映体过量)和 98.8% ee。此外,有效地进行了克级实验。
Preparative access to medicinal chemistry related chiral alcohols using carbonyl reductase technology
作者:Andrew S. Rowan、Thomas S. Moody、Roger M. Howard、Toby J. Underwood、Iain R. Miskelly、Yanan He、Bo Wang
DOI:10.1016/j.tetasy.2013.09.015
日期:2013.11
Libraries of highly enantioenriched secondary alcohols in both enantiomeric forms were synthesised by enzymatic reduction of their parent ketones using selectAZyme (TM) carbonyl reductase (CRED) technology. Commercially available CREDs were able to reduce a range of substrate classes efficiently and with very high enantioselectivity. Matching substrate classes to small subsets of CREDs enabled the fast development of preparative bioreductions and the rapid generation of 100-1500 mg samples of chiral alcohols in typically >95% ee and the majority in >= 99.0% ee. The conditions for small scale synthesis were then scaled up to 0.5 kg to deliver one of the chiral alcohols, (S)-1-(4-bromophenyl)-2-chloroethanol, in 99.8% ee and 91% isolated yield. (C) 2013 Elsevier Ltd. All rights reserved.
A novel C3-symmetric prolinol-squaramide catalyst for the asymmetric reduction of ketones by borane
A novel C-3-symmetric prolinol-squaramide has been developed for the asymmetric reduction of ketones by borane. By using only 5 mol % catalyst la for the reaction, high yields and excellent enantioselectivities (up to 95% yield, 93% ee) were obtained. Moreover, la can be easily recovered by simple precipitation and re-used for four cycles without losing the selectivity. (C) 2011 Elsevier Ltd. All rights reserved.
Unmasking the Hidden Carbonyl Group Using Gold(I) Catalysts and Alcohol Dehydrogenases: Design of a Thermodynamically-Driven Cascade toward Optically Active Halohydrins
A concurrent cascade combining the use of a gold(I) N-heterocyclic carbene (NHC) and an alcohol dehydrogenase (ADH) is disclosed for the synthesis of highly valuable enantiopure halohydrins in an aqueous medium and under mild reaction conditions. The methodology consists of the gold-catalyzed regioselective hydration of easily accessible haloalkynes, followed by the stereoselective bioreduction of