title: Direct Conversion of Aldehydes and Ketones to Allylic Halides by a NbX(5-)[3,3] Rearrangement.
abstract: Sequential addition of vinylmagnesium bromide and NbCl(5), or NbBr(5), to a series of aldehydes and ketones directly provides homologated, allylic halides. Transposition of the intermediate vinyl alkoxide is envisaged through a metalla-halo-[3,3] rearrangement with concomitant delivery of the halogen to the terminal carbon. The [3,3] rearrangement is equally effective for the conversion of a propargyllic alcohol to the corresponding allenyl bromide.
authors.affiliation: Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530.
authors.forename: Fraser F
authors.initials: FF
authors.lastname: Fleming
authors.forename: P C
authors.initials: PC
authors.lastname: Ravikumar
authors.forename: Lihua
authors.initials: L
authors.lastname: Yao