The γ-alkylation of cyclic β-ketoesters via their enamine derivatives

The γ-alkylation – functionalization of cyclic β-ketoesters via their enamine derivatives is discussed with particular emphasis on their preparation from β-ketoesters and their reaction with various electrophiles such as electrophilic olefins, halogenoïds, and allylic and benzylic halides. Although the amine ring size does not appear to affect reactivity to a great extent, the reaction is very sensitive to β-ketoester ring size, with six-membered rings giving the best results. In the latter case the alkylation–functionalization is general and specific to the γ-position and therefore provides an important complement to the dianion and related methodologies.