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

Optically pure cyano tert-alkyl sulfones have been obtained by organocatalytic enantioselective Michael addition of alpha-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 degrees C. Reactions proved to be applicable for a variety of alpha,beta-unsaturated ketones. affording alpha,alpha-disubstituted cyanosulfones in excellent yields with er's up to 90:10.