Chiral tricyclic iminolactone derived from (1R)-(+)-camphor as a glycine equivalent for the asymmetric synthesis of α-amino acids

The development of a highly efficient and stereoselective methodology for the preparation of alpha-amino acids is described. The chiral template, tricyclic iminolactone 7, was synthesized from (1R)-(+)camphor in five steps in 50% overall yield. Alkylation of iminolactone 7 afforded the CL-monosubstituted products in good yields (74-96%) and excellent diastereoselectivities (>98%). Hydrolysis of the alkylated iminolactones furnished the desired alpha-amino acids in good yields and enantioselectivities with nearly quantitative recovery of the chiral auxiliary 4.