Ethyl 2,2-bis(4-methylphenylsulfonamido)acetate to aromatic alpha-amino acids: stable substrates for catalytic arylation reactions

This paper reports the development of a novel methodology for the catalytic synthesis of aromatic alpha-amino acids, which involves the addition of aryl-organoboron reagents to alpha,alpha-ditosylamino esters derived from ethyl glyoxylate, using transition metal catalysts, like Rh and Pd. A library of alpha-amino esters (12 with Pd and 8 with Rh), was synthesized with moderate to excellent yields. A highest enantioselectivity of 30% ee was obtained using Hayashi's ligand. This method was applied to the synthesis of phenylglycine