Organocatalytic enantioselective addition of thiols to ketimines derived from isatins.

The first catalytic enantioselective addition of thiols to ketimines derived from isatins has been developed. Excellent yields and enantioselectivities were observed for the reaction of various ketimines and thiols using a cinchona alkaloid sulfonamide catalyst. Both enantiomers of products could be obtained by using pseudoenantiomeric chiral catalysts.