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

Tin(IV) chloride selectively promotes the nucleophilic attack of methyl acetoacetate to the cyano instead of the olefinic carbon atom of α,β-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.