Asymmetric synthesis of erythro- and threo-2-(1-hydroxyalkyl)piperidines via iodocyclocarbamation of 1-acyl-2-alkenyl-1,2,3,6-tetrahydropyridines

An iodocyclocarbamation procedure has been developed for the stereoselective preparation of erythro- and threo-2-(1-hydroxyalkyl)piperidines. This methodology was utilized in the asymmetric synthesis of two piperidine alkaloids, (+)-α-conhydrine and (+)-β-conhydrine.