Catalytic, Asymmetric Synthesis of 1,4‐Benzoxazinones: A Remarkably Enantioselective Route to α‐Amino Acid Derivatives from o‐Benzoquinone Imides

Cycloaddition of o-benzoquinone imides with chiral ketene enolates derived from cinchona alkaloid catalysts is the basis of a catalytic asymmetric synthesis of 1,4-benzoxazinones and 1,4-benzoxazines. The resulting cycloadducts can be derivatized in situ to provide α-amino acid products in good-to-excellent yields with very high enantioselectivities (see scheme; CAN=ceric ammonium nitrate, Nu=nucleophile).