Studies in organophosphorus chemistry : Reaction of epoxides with tertiary phosphine dihalides

Abstract

The reaction of tertiary phosphine dichlorides and dibromides with epoxides gives vicinal dihalides. The reaction involves initial cleavage of the epoxide carbon—oxygen bond emanating from the most highly substituted epoxide carbon. Haloalkoxyphosphonium salts are thus formed which undergo subsequent reaction giving vicinal dihalides and tertiary phosphine oxides. The vicinal dihalides which result from epoxides of cyclohexenes are mixtures of cis and trans isomers in which the cis isomer is formed by backside attack of halogen at both epoxide carbons.