Alkylation of enol ethers obtained by treatment of α,β-unsaturated acetals with organopotassium reagents: an inverse polarity approach

Abstract

The reaction of α,β-unsaturated acetals 1–4 with sec-butyllithium (2 equiv.) in the presence of potassium tert-butoxide in tetrahydrofuran at –95 °C gave, as a result of 1,4 elimination, α-metallated enol ethers. The latter react with alkyl halides and carbonyl compounds to afford substitution and addition products. In particular, for the reaction with the acetal 1 and D₂O as the electrophile, the α-deuteriated enol ether 5 cyclizes to [2-²H]-2-(prop-1-enyl)-1,3-dioxane.