Organocatalytic enantioselective sulfa-Michael addition of thiocarboxylic acids to beta-trifluoromethyl-alpha,beta-unsaturated ketones for the construction of stereogenic carbon center bearing a sulfur atom and a trifluoromethyl group

摘要

An organocatalyzed asymmetric sulfa-Michael addition of thiocarboxylic acids to beta-trifluoromethyl-alpha,beta-unsaturated ketones with a chiral bifunctional amine-squaramide as the catalyst is presented. A wide range of chiral ketone compounds bearing a sulfur atom and a trifluoromethyl group at the stereogenic carbon center could be obtained with excellent results (up to 99% yield, 97% ee) under mild conditions. The developed catalytic system is well-tolerated to both (E)-and (Z)-beta-trifluoromethylated-alpha,beta-unsaturated ketones. (C) 2019 Elsevier Ltd. All rights reserved.