Catalytic Aerobic Cross-Dehydrogenative Coupling of Azlactones en Route to α,α-Disubstituted α-Amino Acids.

We developed a catalytic aerobic method to synthesize α,α-disubstituted α-amino acids through cross-dehydrogenative coupling of azlactones. Combining an iron catalyst with a bisoxazolidine ligand resulted in high catalytic performance, and cross-coupling with an indole proceeded smoothly under aerobic conditions. A wide variety of α-aryl and aliphatic amino acid derived azlactones were applied to the present catalysis. In addition, a quaternary carbon could be constructed using oxindole and benzofuranone under aerobic conditions.