Novel synthesis of pyrrolidinones by cobalt carbonyl catalyzed carbonylation of azetidines. A new ring-expansion-carbonylation reaction of 2-vinylazetidines to tetrahydroazepinones

Abstract

Pyrrolidinones can be synthesized in high yields and regioselectivity by the cobalt carbonyl catalyzed carbonylation of azetidines. For 2-substituted azetidines (alkyl, aryl, CH 2 OH, CH 2 OR, CH 2 OCOR, and COOR), carbonyl insertion occurs in the more or less substituted ring carbon-nitrogen bond depending on the kind of substituent group and on the reaction temperature. In the case of 2-vinylazetidines, ring expansion and crbonylation affords seven-membered-ring tetrahydroazepinones. Good functional group tolerance was observed in these reactions