A New Methodology for Stereocontrolled Carbon-Carbon Bond Formation. Frontier Orbital- and Chelation-Controlled Diastereoselective Michael Additions of α-Amino Esters Leading to Unnatural Amino Acid Derivatives

The rigid transition state, proposed previously for the stereoselective cycloadditions of N-metalated azomethine ylides, has been successfully applied to establish highly stereoselective Michael additions of methyl (2,2-dimethylpropylideneamino) acetate with α, β-unsaturated carbonyl compounds. Use of camphor imines of glycinates offers an efficient method for diastereoselective Michael additions to produce the optically active α-amino ester derivatives of unnatural types