Asymmetric Michael addition of malonic diesters to acrylates by phase-transfer catalysis toward the construction of quaternary stereogenic α-carbons

Abstract

A highly enantioselective construction of an all-carbon quaternary stereogenic center at the α-position of malonic diesters has been achieved by Michael addition using phase-transfer catalysis. The reaction of α-monosubstituted malonates with acrylates in the presence of N-(9-anthracenylmethyl)quininium chloride as a phase-transfer catalyst afforded the corresponding α,α-disubstituted malonic diesters in high chemical yields (up to >95% yield) with high enantioselectivities (up to 95% ee). Furthermore, the product was amenable to chemoselective transformation and could be successfully converted to the corresponding α,α-disubstituted amino acid derivatives through Curtius rearrangement.