A new pyridone alkaloid, cerpegin, was synthesized in five steps starting from the Michael reaction between phenylthioacetonitrile and 2-methoxycarbonyl-4-methyl-2-penten-4-olide. Catalytic hydrogenation of a nitrile group in the presence of a conjugated carbon-carbon double bond was performed by addition of 1 eq of concentrated HCl. © 1995, The Pharmaceutical Society of Japan. All rights reserved.