Enantioselective Organocatalytic Approach to the Synthesis of α,α-Disubstituted Cyanosulfones

Optically pure cyano tert-alkyl sulfones have been obtained by organocatalytic enantioselective Michael addition of α-substituted cyanosulfones to vinyl ketones using cinchona alkaloids as catalysts. The best results were obtained for p-trifluorophenylsulfones by using VIII as catalyst in toluene at −40 °C. Reactions proved to be applicable for a variety of α,β-unsaturated ketones, affording α,α-disubstituted cyanosulfones in excellent yields with er’s up to 90:10.