Iridium-catalyzed Asymmetric Hydrogenation of Pyridinium Salts for Constructing Multiple Stereogenic Centers on Piperidines

A salt formation strategy for asymmetric hydrogenation of pyridines is described. Poly-substituted pyridinium salts were successfully hydrogenated using chiral iridium dinuclear complexes to afford substituted piperidines with multiple stereogenic centers after a simple basic workup.