Catalytic asymmetric synthesis of piperidines from pyrrolidine: concise synthesis of L-733,060.

Catalytic asymmetric deprotonation-aldehyde trapping-ring expansion from a 5- to a 6-ring delivers a concise route to each stereoisomer of beta-hydroxy piperidines starting from N-Boc pyrrolidine. The methodology is utilized in a 5-step catalytic asymmetric synthesis of the neorokinin-1 receptor antagonist, (+)-L-733,060.