Organocatalytic cascade sulfa-Michael/aldol reaction of β,β-disubstituted enones: enantioselective synthesis of tetrahydrothiophenes with a trifluoromethylated quaternary center.

A bifunctional squaramide-catalyzed sulfa-Michael/aldol cascade reaction initiated by sulfa-Michael addition of mercaptoacetaldehyde to β-aryl-β-trifluoromethylated enones is successfully developed. The functionalized tetrahydrothiophenes with three continuous stereocenters including a trifluoromethylated quaternary carbon are readily obtained with moderate to good yields and high enantioselectivities.