Ketovinylation of β-dicarbonyl compounds

Abstract

The introduction of the ketovinyl group into β-dicarbonyl compounds with only one labile hydrogen proceeds normally, but the presence of two labile hydrogens results in the formation of complex mixtures. Ethyl malonate and ethyl acetoacetate have, however, been successfully ketovinylated. In the former case, α-carbethoxy-δ-keto-β,γ-unsaturated acids are produced in high yield and depending on the conditions of ketovinylation of ethyl acetoacetate either 4-alkyl salicyclic acids or polysubstituted benzene derivatives may be prepared. Further, the ketovinylation products of ethyl malonate and alkyl acetoacetates may be used for the synthesis of either (1) unsaturated aliphatic keto acids or diketones or (2) a variety of α-pyrone derivatives. A mechanism for the ketovinylation of ethyl acetoacetate is proposed and the trans configuration of the ketovinylation products established.