Aromatic alkenylation using electrophilic organogallium reagent generated from allenylsilane and GaCl3

Aromatic hydrocarbons are alkenylated with silylallene in the presence of GaCl3 at −90°C. Organometallic electrophiles generated from the allene and GaCl3 are the active species in this reaction. A modest level of ortho-selectivity is observed. While the silylallene reacts exclusively at the 2-position, 1,2-alkadiene reacts at the 1-position predominantly.