Catalytic Route to the Synthesis of Optically Active β,β-Difluoroglutamic Acid and β,β-Difluoroproline Derivatives

β,β-Difluorinated amino acid derivatives were synthesized via Mg(0)-promoted defluorination of α-trifluoromethyl iminoester. Bromination of the difluoroenamine afforded the bromodifluoromethyl iminoester in good yield. Pd-catalyzed asymmetric hydrogenation of the bromodifluoromethyl iminoester and the subsequent transformations provided optically active β,β-difluoroglutamic acid and β,β-difluoroproline derivatives.