Catalytic Enantioselective Silylation of N-Sulfonylimines: Asymmetric Synthesis of α-Amino Acids from CO2 via Stereospecific Carboxylation of α-Amino Silanes

A catalytic enantioselective silylation of N-tert-butylsulfonylimines using a Cu-secondary diamine complex was demonstrated. The resulting optically active α-amino silanes could be carboxylated under a CO2 atmosphere (1 atm) to afford the corresponding α-amino acids in a stereoretentive manner. This two-step sequence provides a new synthetic protocol for optically active α-amino acids from gaseous CO2 and imines in the presence of a catalytic amount of a chiral source.