Enantioselective synthesis of α-nitro-δ-ketosulfones via a quinine-squaramide catalyzed conjugate addition of α-nitrosulfones to enones

Conjugate addition of alpha-nitrosulfones to vinyl ketones in the presence of 0.2 mol% of a quinine-squaramide organocatalyst afforded alpha-nitro-delta-ketosulfones possessing a tetrasubstituted chiral center in excellent yield and enantioselectivity in most cases. This strategy also offers a facile and convenient entry into gamma-sulfonylhydroxamates that are one carbon homologs of potent enzyme inhibitors.