Acylation du (cyclopropylméthyl)triméthylsilane. Une nouvelle voie d'accès aux énones non conjuguées

Acylation of (cyclopropylmethyl)trimethylsilane using RCOCl/AlCl 3 (R: saturated hydrocarbon group) constitutes a mild, convenient route to β,γ-unsaturated ketones free from the conjugated isomers. With α,β-unsaturated acyl chlorides a competitive reaction between the CH and CSi allylic cleavage is observed whereas chloroacetyl chloride affords the γ,δ-ethylenic corresponding ketone. A mechanism involving the catalytic role of HCl in the formation of β,γ-unsaturated and chloroketones is proposed.