Organocatalyzed Asymmetric 1,4-Addition of Azlactones to α,β-Unsaturated Trichloromethyl Ketones: Synthesis of α,α-Disubstituted α-Amino Acid Derivatives
作者:Jinlong Zhang、Xihong Liu、Chongyang Wu、Panpan Zhang、Jianbo Chen、Rui Wang
DOI:10.1002/ejoc.201403158
日期:2014.11
4-addition of azlactones to α,β-unsaturated trichloromethyl ketonescatalyzed by cinchonaalkaloid derived bifunctional thiourea catalysts was developed. A series of α,α-disubstituted α-amino acid derivatives bearing a quaternary stereocenter at the α-position were obtained in high yields with excellent diastereo- and enantioselectivities (up to -20:1 dr and 99% ee). In addition, the trichloromethyl moiety
The enantioselective Michael addition of alpha-cyanoketones to alpha,beta-unsaturated trichloromethyl ketones was firstly reported. With a phenylalanine-derived bifunctional piperazine/thiourea catalyst, a series of alpha-trichloromethyldihydropyrans were obtained with up to 95% ee and 99% yield. (C) 2011 Elsevier Ltd. All rights reserved.