A halide-initiated aza-Baylis–Hillman reaction: generation of unnatural amino acids

A series of allenic ketones react with a glyoxylate-derived imine in the presence of MgBr2 through an aza-Morita–Baylis–Hillman (MBH) reaction. The isolation of a variety of unnatural amino acids with unique allene-containing functional groups provides a conceptually new application of the aza-MBH. The reaction scope and preliminary mechanistic investigations are discussed.