Iridium-catalyzed selective hydrogenation of 3-hydroxypyridinium salts: a facile synthesis of piperidin-3-ones.

The selective hydrogenation of 3-hydroxypyridinium salts has been achieved using a homogeneous iridium catalyst, providing a direct access to 2- and 4-substituted piperidin-3-one derivatives with high yields, which are important organic synthetic intermediates and the prevalent structural motifs in pharmaceutical agents. Mild reaction conditions, high chemoselectivity, and easy scalability make this reaction highly practical for the synthesis of piperidin-3-ones.