Enantioselective synthesis of (S)-4-methyleneglutamic acid via tandem conjugate addition–elimination under phase-transfer catalytic conditions

Abstract An efficient enantioselective synthetic method for ( S )-4-methyleneglutamic acid is reported. Phase-transfer catalytic conjugate addition–elimination of the benzophenone imine of glycine tert -butyl ester in the presence of chiral Cinchona -derived catalysts give the corresponding conjugated addition products (>99% ee), which could be hydrolyzed to chiral ( S )-4-methyleneglutamic acid.