Enantioselective Reduction of Pyridines via Brønsted Acid Catalysis

Significance

An organocatalytic enantioselective reduction of 2-substituted simple and fused pyridines is reported. The reaction is designed to undergo catalytic protonation by Brønsted acid 1, followed by reduction by hydride transfer from the Hantzsch dihydropyridine 2. The hexahydroquinolinone and tetrahydropyridine products are formed in moderate to good yields with good enantioselectivities. The scope of the reaction was modestly investigated.