Highly enantioselective sulpha-Michael addition to α,β-unsaturated carbonyl scaffolds catalysed by allyloxy-N-(1-benzyl) cinchonidinium bromide in water at room temperature

Allyloxy-N-(1-benzyl) cinchonidinium bromide was found to be an effective organocatalyst for asymmetric Michael reactions of thiols with various alpha,beta-unsaturated ketones, acids and esters to provide optically active sulphides with high enantiomeric excess (91-100% ee) and chemical yields (up to >98%). The reaction was performed with 2-8 mol % of catalyst in water at room temperature using tetra-n-butyl ammonium fluoride as an additive. (C) 2016 Elsevier Ltd. All rights reserved.