On the effect of ring substituents in the carbonylation of aziridines

The effect of ring substituents on the cobalt carbonyl-catalyzed carbonylat ion of functionalized aziridines to beta -lactams has been investigated. A variety of aziridines with different substituents and stereochemistry has b een synthesized and subjected to carbonylation. The ring expansion to beta -lactam takes place in the absence of an electron-withdrawing substituent a nd higher yields are always obtained for cis-aziridines. Moreover, the regi oselectivity of the reaction is affected by the nature of substituents at r ing carbon atoms. (C) 2001 Elsevier Science Ltd. All rights reserved.