Highly Enantioselective Intermolecular Cyclopropanation Catalyzed by Dirhodium(II) Tetrakis[3(S)-phthalimido-2-piperidinonate]: Solvent Dependency of the Enantioselection
Highly Enantioselective Intermolecular Cyclopropanation Catalyzed by Dirhodium(II) Tetrakis[3(S)-phthalimido-2-piperidinonate]: Solvent Dependency of the Enantioselection
Asymmetric copper-catalyzed cyclopropanation of trisubstituted and unsymmetrical cis-1,2-disubstituted olefins: modified bis-oxazoline ligands
作者:Richard E. Lowenthal、Satoru Masamune
DOI:10.1016/0040-4039(91)80110-r
日期:1991.12
The Cu(I) complexes of newbis-oxazolines (3–7) prepared from the corresponding amino alcohols and malono-bis-imidate exhibit high enantioselectivity of up to 94 %ee in the catalytic cyclopropanation of trisubstituted and unsymmetrical cis-1,2-disubstituted olefins. New diazoacetate reagents have also been developed giving high trans/cis ratios of up to 99:1 trans.
Synthesis of imine–amine type of chiral ligands and their application in the asymmetric cyclopropanation of olefins with diazoacetates
作者:Jun-An Ma、Li-Xin Wang、Wei Zhang、Qi-Lin Zhou
DOI:10.1016/s0957-4166(01)00513-4
日期:2001.11
Novel chiral ligands 1, which possess both imine and amine moieties, were prepared from readily available homochiral materials. Copper complexes of 1 were prepared in situ and used in the asymmetriccyclopropanation of olefins with alkyl diazoacetates to give cyclopropanecarboxylates, inducing e.e. values of up to 87%. The size of the chelate ring in the copper complexes influenced the enantioselectivity
Chiral quinolinyl-oxazolines as ligands for copper(I)-catalyzed asymmetric cyclopropanation
作者:Xin-Yan Wu、Xiang-Hong Li、Qi-Lin Zhou
DOI:10.1016/s0957-4166(98)00455-8
日期:1998.12
Chiral quinolinyl-oxazoline compounds have been synthesized from enantiomerically pure amino alcohols and 8-quinoline-carboxylic acid using a convenient procedure. Asymmetric cyclopropanation of styrene with diazo-acetates in the presence of 1 mol% of CuOTf and quinolinyl-oxazolines gave 2-phenylcyclopropane carboxylates in moderate enantiomeric excesses. (C) 1998 Elsevier Science Ltd. All rights reserved.