A New Synthesis of All Four Stereoisomers of 2-(2,3-Dihydroxypropyl)piperidine via Iterative Asymmetric Dihydroxylation To Cause Enantiomeric Enhancement. Application to Asymmetric Synthesis of Naturally Occurring Piperidine-Related Alkaloids

Abstract

Both enantiomers of 2-(2-propenyl)piperidine 1 (76−88% ee), prepared via the first asymmetric dihydroxylation (AD) of 5-hexenyl azide, underwent the second AD to provide all four of the stereoisomeric 2-(2,3-dihydroxypropyl)piperidines 2 with enantiomeric enhancement (>98% ee). An asymmetric synthesis, starting from 2, of several 2-(2-hydroxyalkyl)piperidine alkaloids [(−)-halosaline, (+)- N -methylallosedridine, (+)-8-ethylnorlobelol, (+)-sedridine, (+)-allosedridine, (−)-allosedridine, and (+)- N -methylsedridine] and the ant defense alkaloids [(+)-tetraponerine-3 ( T-3 ), T-4, T-7, and T-8 ] is demonstrated.