High diastereo- and enantioselective Michael addition of 3-acetoxy-2-oxindoles with nitroalkenes catalyzed by nickel/PyBisulidine

Abstract

A Ni/PyBisulidine catalyzed asymmetric Michael addition of 3-acyloxy-2-oxindoles to nitroalkenes has been developed. Various quaternary substituted 3-acyloxy-2-oxindoles were obtained with excellent yields and diastereo- and enantioselectivities in a low-toxic green solvent, ethyl acetate, with a low catalyst loading (1 mol%). The reaction process is air and moisture tolerant. The substrate scope was also extended to α,β-disubstituted nitroalkenes and 3-hydroxy-2-oxindoles, and good results were obtained.