Chlorination of Acyclic β-Diketones. Formation and Stability of β-Chloro-β,γ-unsaturated Ketones

Abstract

Abstract Chlorination of acyclic β-diketones with triphenylphosphine–carbon tetrachloride and the other chlorinating reagents predominantly afforded β-chloro-β,γ-unsaturated ketones except the cases of the terminal alkyl group of the diketones was methyl or t-butyl. In these reactions, the isomerization of the β-chloro-α,β-unsaturated ketones to the β,γ-unsaturated isomers was involved; the isomerization was achieved by triphenylphosphine–carbon tetrachloride as well as by some acid catalysts.