A rapid and highly efficient copper(II)-catalyzed cross-dehydrogenative coupling (CDC) reaction of N-arylglycine esters with imidazo[1,2-a]pyridines has been described. A broad range of N-arylglycine esters underwent the CDC reaction smoothly with 2-arylimidazo[1,2-a]pyridines to give α-substituted α-amino acid esters in excellent yields. This synthetic method has the advantages of high yields, good functional groups compatibility, simple operation, and mild reaction conditions. A possible mechanism for the CDC reaction is also proposed. The use of a copper salt as the catalyst and air as the terminal oxidant makes this transformation sustainable and practical.
Key words
cross-dehydrogenative coupling - copper - glycine ester - imidazo[1,2-
a]pyridine - imine