Squaramide-catalyzed diastereo- and enantioselective Michael addition of 3-substituted oxindoles to nitroalkenes

Abstract

An efficient diastereo- and enantioselective Michael addition of 3-substituted oxindoles onto nitroalkenes catalyzed by a bifunctional chiral squaramide catalyst has been developed. This organocatalytic reaction with 2mol% of catalyst proceeded smoothly to afford 3,3-disubstituted oxindoles in high yields with good diastereoselectivities and enantioselectivities (up to 98:2 dr, 88% ee).