Enantiomerically pure 2,2-dibromocyclopropanecarboxylic acids, simple chiral building blocks
作者:Mark S. Baird、Peter Licence、Viacheslav V. Tverezovsky、Ivan G. Bolesov、William Clegg
DOI:10.1016/s0040-4020(99)00048-4
日期:1999.2
Simple chiralbuildingblocks 1-(R)- and 1-(S)-2,2-dibromocyclopropanecarboxylic acids and 2-(R)-bromo-1-(S)-cyclopropanecarboxylic acids and their 1-methyl analogues, have been obtained on a preparatively useful laboratory scale.
Synthesis of (2S, 3R, 4S)-3,4-methanoproline and analogues by cyclopropylidene insertion
作者:Viacheslav V. Tverezovsky、Mark S. Baird、Ivan G. Bolesov
DOI:10.1016/s0040-4020(97)00988-5
日期:1997.10
Intramolecular insertion of single enantiomers of cyclopropylidenes into 5,6-related CH bonds adjacent to nitrogen has been used to obtain enantiomerically pure methanoproline and a number of analogues with a high degree of one- or two-fold asymmetric induction.
A general and efficient method for the preparative resolution of alpha- and beta-bromocyclopropylcarboxylic acids has been developed. This protocol involves a sequence of two crystallizations with pseudo-enantiomeric amines, cinchonine, and cinchonidine, which yield both enantiomers of the acid in highly enriched form. Both alkaloids can be easily recovered and reused multiple times without any loss of efficacy. (C) 2014 Elsevier Ltd. All rights reserved.
Rational design of cyclopropane-based chiral PHOX ligands for intermolecular asymmetric Heck reaction
作者:Marina Rubina、William M Sherrill、Alexey Yu Barkov、Michael Rubin
DOI:10.3762/bjoc.10.158
日期:——
rigid cyclopropyl backbone was synthesized and tested in the intermolecularasymmetricHeck reaction. Mechanistic modelling and crystallographic studies were used to predict the optimal ligand structure and helped to design a very efficient and highly selective catalytic system. Employment of the optimized ligands in the asymmetricarylation of cyclic olefins allowed for achieving high enantioselectivities
Practical, general, and systematic method for optical resolution of gem-dihalo- and monohalocyclopropanecarboxylic acids utilizing chiral 1,1′-binaphtholmonomethyl ethers: Application to the synthesis of three chiral pesticides
We performed an efficient practical and systematic optical resolutionmethod for gem-dihalo- and monohalocyclopropanecarboxylic acids and utilizing chiral 1,1'-binaphthol monomethyl ether (R)- as the key auxiliary. Direct esterification of with (R)- gave two 1R- and 1S-diastereomeric esters with marked different R(f) values, both of which were easily separated using simple column chromatography. Monodehalogenation