An Efficient Synthesis of Cyclic (beta)-Amino Acid Derivatives as (beta)-Turn Mimetics

Seven-, eight-, and nine-membered cyclic (beta)-amino acids, precursors of platelet aggregation inhibitors, were synthesized for the first time starting from N-alkenyl amines and ethyl acrylate via ring-closing metathesis (RCM) as the key reaction. Synthesis of the corresponding enantiomerically pure (beta)-amino acids was also accomplished in a similar manner using Evans’ asymmetric allylation.