Photochemically induced radical alkynylation of C(sp3)-H bonds.

A general strategy for photochemical alkynylation of unreactive C(sp(3))-H bonds has been developed. After C-H abstraction by the photo-excited benzophenone, a two-carbon unit was efficiently transferred to the generated radical from 1-tosyl-2-(trimethylsilyl)acetylene to afford the alkynylated product. The present reaction enables construction of various tri- and tetra-substituted carbons from heteroatom-substituted methylenes, methines and alkanes in a highly chemoselective fashion, and would serve as a new synthetic strategy for rapid construction of complex structures.