Iron-catalyzed arylmagnesiation of aryl(alkyl)acetylenes in the presence of an N-heterocyclic carbene ligand.

Addition of arylmagnesium bromides to aryl(alkyl)acetylenes proceeded in the presence of an iron catalyst and a N-heterocyclic carbene ligand to give high yields of the corresponding alkenylmagnesium reagents, which were transformed into tetrasubstituted alkenes by subsequent treatment with electrophiles. [reaction: see text]