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 α-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 α-monosubstituted products in good yields (74−96%) and excellent diastereoselectivities (>98%). Hydrolysis of the alkylated iminolactones furnished the desired α-amino acids in good yields and enantioselectivities with nearly quantitative recovery of the chiral auxiliary 4.