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

Both enantiomers of 2-(2-propenyl)piperidine 1 (76-88% ee), prepared via th e first asymmetric dihydroxylation (AD) of 5-hexenyl azide, underwent the s econd AD to provide all four of the stereoisomeric 2-(2,3-dihydroxypropyl)p iperidines 2 with enantiomeric enhancement (>98% ee). An asymmetric synthes is, starting from 2, of several 2-(2-hydroxyalkyl)piperidine alkaloids [(-) -halosaline, (+)-N-methylallosedridine, (+)-8-ethylnorlobelol, (+)-sedridin e, (+)-allosedridine, (-)-allosedridine, and (+)-N-methylsedridine] and the ant defense alkaloids [(+)-tetraponerine-3 (T-3), T-4, T-7, and T-8] is de monstrated.