Synthesis of high enantiomeric purity gem-dihalocyclopropane derivatives from biotransformations of nitriles and amides
摘要:
Enantioselective biotransformations of geminally dihalogenated cyclopropanecarbonitriles and amides are described. Both the reaction rate and enantioselectivity of the nitrile hydratase and amidase involved in Rhodococcus sp. AJ270 microbial cells are strongly governed by the nature of gein-disubstituents on the cyclopropane ring; the amidase generally exhibits steric dependence on the substituents while both the steric and electronic factors of the substituents may affect the action of the nitrile hydratase. The match of steric bulkiness of the substituents at 2- with that at 3-positions on the cyclopropane ring benefits the efficient and highly enantioselective reaction. Coupled with facile chemical transformations, biocatalytic transformations of nitrile and amide supply an effective synthesis of optically active 2,2-disubstitued-3-phenylcyclopropanecarboxylic acid and amide in both enantiomeric forms. (C) 2003 Elsevier Ltd. All rights reserved.
Transition Metal‐free
<i>gem</i>
‐difluorocyclopropanation of Alkenes with CF
<sub>3</sub>
SiMe
<sub>3</sub>
−NaI System: a Recipe for Electron‐deficient Substrates
作者:Pavel S. Nosik、Sergey V. Ryabukhin、Oleksandr O. Grygorenko、Dmitriy M. Volochnyuk
DOI:10.1002/adsc.201801006
日期:2018.11.5
Reaction of various electron‐deficientalkenes, as well as functionalized styrene derivatives with CF3SiMe3−NaI system is studied. Relative reactivity of the substrates is established. It is shown that many α,β‐unsaturated esters can be difluorocyclopropanated efficiently under “slow addition protocol” conditions, which provides access to mono‐ and spirocyclic gem‐difluorocyclopropyl‐substituted carboxylic
Difluorocarbene Addition to Alkenes and Alkynes in Continuous Flow
作者:Pauline Rullière、Patrick Cyr、André B. Charette
DOI:10.1021/acs.orglett.6b00573
日期:2016.5.6
The first in-flow difluorocarbene generation and addition to alkenes and alkynes is reported. The application of continuousflow technology allowed for the controlled generation of difluorocarbene from TMSCF3 and a catalytic quantity of NaI. The in situ generated electrophilic carbene reacts smoothly with a broad range of alkenes and alkynes, allowing the synthesis of the corresponding difluorocyclopropanes