Zinc-Mediated C−C Bond Sigmatropic Rearrangement:  A New and Efficient Methodology for the Synthesis of β-Diketones

A new and efficient methodology has been developed for the synthesis of β-diketones from aromatic α-bromo ketones in the presence of Furukawa reagent under mild conditions. The present transformation is proposed to proceed via a Reformatsky-type reaction of α-bromo ketones, followed by C−C bond sigmatropic rearrangement of the aldolate intermediate to give β-diketones in moderate to good isolated yields, while aliphatic α-bromomethyl ketones resulted in the formation of 2,4-disubstituted furans or cis-1,2-disubstituted cyclopropanols in moderate yields. The scope of this process was investigated, and a tentative mechanism was proposed.