Multiple Rhodium-Catalyzed Cleavages of Single C–C bonds

The Rh(I)-catalyzed intramolecular hydroacylation of cis and trans asymmetrically substituted alkylidenecyclobutanes proceeds according to three mechanistic pathways. As shown by deuterium-labeling experiments, the mechanism accounting for the rearrangement of the cis isomers includes the cleavage of three carbon–carbon bonds and a remarkable transannular 3-exo-trig carbometalation.