Bromotriphenylphosphonium bromide

The Vilsmeier-Haack formylation procedure (Scheme 24) provides the most effective synthesis of formylpyrroles and indoles. Reaction of the heterocycles with the immonium cation (72), derived from DMF or (V-methylformanilide with an acid chloride, such as phosphorus oxychloride, thionyl chloride, phosgene, oxalyl chloride, benzoyl chloride or bromotriphenylphosphonium bromide, yields the intermediate heteroarylimmonium salt (73). Under suitable reaction conditions, this salt may be isolated from the reaction involving phosphorus oxychloride as an impure chlorophosphate (78TH30500) or precipitated from the reaction system as the thermally unstable perchlorate by the addition of sodium... 

A number of acyclic <7-dialkoxyphosphoranes (18) have been prepared in moderate to high yields by the reaction of bromotriphenylphosphonium bromide (17) with the relevant sodium alkoxide in alcohol and ethereal solvents. The method offers obvious advantages over the peroxide route and in some cases (R=Pr ) higher yields than the Mitsunobu reaction but at the... 

Alternate Names bromotriphenylphosphonium bromide dibro-motriphenylphosphorane. 

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