Sodium-Mediated Reductive anti-Dimagnesiation of Diarylacetyl­enes with Magnesium Bromide

Abstract Diarylacetylenes undergo anti-dimagnesiation using magnesium bromide and sodium dispersion to afford (E)-1,2-dimagnesioalkenes. This dimagnesiation utilizes simple magnesium bromide as a reduction-resistant electrophile, contrasting with the previously reported dimagnesiation using tricky organomagnesium halides. The resulting vicinal double Grignard reagents react with various electrophiles to yield multisubstituted alkenes stereoselectively.