Preparation of Enantiopure Substituted Piperidines Containing 2-Alkene or 2-Alkyne Chains: Application to Total Syntheses of Natural Quinolizidine-Alkaloids

摘要

A number of natural alkaloids contain the unit of chiral 2-substituted piperidine.1 For their biological importance and novel structures, they have continuously been the challenging targets of total synthesis. Various building blocks have been applied to this purpose, prominent among them are chiral 2-alkene-containing chain substituted piperidines, because the alkene group can be easily transformed into other groups by using different reactions, such as aza-Claisen rearrangement,2 hydroxylation,3 catalytic hydrogenation,4 iodine-catalyzed lactonization,5 RCM reaction,6 Wacker oxidation,5 etc. (Scheme 1).