Cerpegin (1), a new pyridone alkaloid, was synthesized starting from the Michael reaction of phenylthioacetonitrile (2) and 2-methoxycarbonyl-4,4-dimethyl-2-buten-4-olide (3) in five steps. Catalytic hydrogenation of a nitrile group in the presence of a conjugated carbon-carbon double bond was performed by addition of 1 eq of conc. HC1. © 1994, The Pharmaceutical Society of Japan. All rights reserved.