LES TRIBROMURES DE PHOSPHONIUMS. AGENTS DE BROMATION DE SUBSTRATS ORGANIQUES

Abstract

Abstract The reactivities and selectivities of phosphonium tribromides 1–4 towards ketones and their ketals, in the presence of other functional group reactive towards bromide (free enolic position, activated aromatic ring or double bond), are studied and compared with the trimethyl phenyl ammonium tribromide 5. The abilities of the two kinds of tribromides are similar, with a better selectivity of phosphoniums salts toward unsaturated ketones, which is probably induced by the greater stability of the ion-pair in phosphonium salts. They act essentially by the tribromide without specific bond interactions between phosphorus and heteroatom of the substrate.