Boron tribromide-catalyzed rearrangement of 7,7-diphenylhydromorphone to 6,7-diphenylmorphine: A novel conversion of ketones to allylic alcohols

A novel boron tribromide-catalyzed rearrangement of ketones to allylic alcohols was discovered in the 7-phenylmorphinan-6-one system. The reaction involved the stereospecific migration of an axial 7β-phenyl (or a hydrogen) to the C-6 carbonyl carbon, followed by the elimination of the H-8 proton leading to the generation of allylic alcohols. A possible mechanistic pathway for this rearrangement is discussed.