Organocatalytic Asymmetric Sulfa-Michael Addition to alfa,beta -Unsaturated Ketones

The highly enantioselective organocatalytic sulfa-Michael addition to α,β-unsaturated ketones has been accomplished using benzyl and tert-butyl mercaptans as the sulfur-centered nucleophiles. Optically active products are obtained in high yields and good to excellent stereocontrol (up to 96% ee) from a large variety of enones. Central to these studies has been the use of the catalytic primary amine salt A, in which both the cation and the anion are chiral, that exhibits high reactivity and selectivity for iminium-ion catalysis with enones