Photo-induced catalyst-free formal carbon insertion of acylsilanes into B-B and B-Si bonds

A formal carbon insertion of acylsilanes into B-B and B-Si bonds has been developed. The in situ formed siloxycarbene from acylsilane under blue LED irradiation worked as the intermediate for the reaction. Commercially available B2(pin)2 and (pin)B-SiMe2Ph were employed as cross partners. No base or catalyst was needed. Both aromatic acylsilanes and aliphatic acylsilanes were applicable. The yields were up to 99% and the utility of the product was demonstrated. When 2-furyl and 2-thiophenyl acylsilanes were used, the B(pin) ring was enlarged to a six-membered ring through the siloxy group rearrangement from carbon to boron. A formal carbon insertion of acylsilanes into B-B and B-Si bonds has been developed. The in situ formed siloxycarbene under blue LED irradiation worked as the intermediate for the reaction. When 2-furyl and 2-thiophenyl acylsilanes were used, the B(pin) ring was enlarged to a six-membered ring.