Rhodium-Catalyzed Intramolecular C-H Silylation by Silacyclobutanes

Silacyclobutane was discovered to be an efficient C-H bond silylation reagent. Under the catalysis of Rh-I/TMS-segphos, silacyclobutane undergoes sequential C-Si/C-H bond activations, affording a series of pi-conjugated siloles in high yields and regioselectivities. The catalytic cycle was proposed to involve a rarely documented endocyclic beta-hydride elimination of five-membered metallacycles, which after reductive elimination gave rise to a Si-Rh-I species that is capable of C-H activation.