Squaramide‐Catalyzed Enantioselective Michael Addition of Diphenyl Phosphite to Nitroalkenes

A new family of chiral catalysts based on the squaramide scaffold is developed, tuned with regard to the chiral environment as well as the pKa of the donor hydrogens, and opens up opportunities for the exploration of new reactions and the development of highly effective catalysts for known reactions.

Abstract

Simple catalyst, high enantioselectivities. An easily prepared squaramide catalyst promotes highly enantioselective Michael addition reactions of diphenyl phosphite to a broad range of nitroalkenes, including those bearing acidic protons or sterically demanding aliphatic substituents. The methodology provides facile access to chiral β-nitro phosphonates, which are precursors to biologically active β-amino phosphonic acids.