One pot synthesis of unsaturated enaminoketoesters or of pyridines in the tin(IV) chloride-promoted reactions of beta-ketoesters with of alpha,beta-unsaturated nitriles

Tin(IV) chloride selectively promotes the nucleophilic attack of methyl acetoacetate to the cyano instead of the olefinic carbon atom of alpha,beta-unsaturated nitriles to give enaminoketoesters. In the presence of an excess of ketoester a second C-C bond formation occurs followed by cyclisation affording substituted pyridines in a selective cascade sequence. (C) 2002 Elsevier Science Ltd. All rights reserved.