Asymmetric Synthesis of (+)-L-733, 060 and (+)-CP-99, 994 Based on a New Chiral 3-Piperidinol Synthon

Selective and potent neurokinin substance P receptor antagonists (+)-L-733, 060 (1) and (+)-CP-99, 994 (2) have been synthesized starting from a new (3S)-piperidinol synthon derived from l-glutamic acid. The methods featured a C-2 regioselective reduction of glutarimide (9), Lewis acid-promoted Si to C-2 phenyl group migration of 10, and stereoselective reduction of acetylated oxime 19 as the key steps.