A Divergent Approach to 3‑Piperidinols: A Concise Syntheses of (+)-Swainsonine and Access to the 1‑Substituted Quinolizidine Skeleton

Nucleophilic addition of Grignard reagents and organolithium species to a 3-silyloxy-3,4,5,6-tetrahydropyridine N-oxide provides trans-2,3-disubstituted N-hydroxypiperidines exclusively. The application of this methodology to the preparation of a diversity of useful trans-2-substituted-3-hydroxypiperidines, a concise synthesis of (+)-swainsonine, and an enantiopure 1-substituted quinolizidine of utility in target-directed synthesis is reported.