A rhodium catalyst induced ring opening of benzocyclobutenols with selective cleavage of the C(sp(2))-C(sp(3)) bond adjacent to the hydroxyl group. The site-selectivity markedly contrasted with that of their thermal ring-opening reaction. The rhodium-catalyzed ring opening led to the development of a new alkyne insertion reaction constructing a dihydronaphthalene framework.
determined by the C-C cleavage step; the C(sp(3))-C(sp(2)) cleavage is favored over the C(sp(3))-C(sp(3)) cleavage because the former transition state is stabilized by an interaction between the benzene ring of the substrate and Rh. DMSO, a more polar solvent, reduces the site selectivity as the more polar C(sp(3))-C(sp(3)) transition state (TS) is stabilized more than the C(sp(3))-C(sp(2)) TS and decreases