Visible Light-Promoted Radical-Mediated Ring-Opening/Cyclization of Vinyl Benzotriazoles: An Alternative Approach to Phenanthridines.

A visible light-promoted radical-mediated ring-opening/cyclization of vinyl benzotriazoles has been developed. The method provides an efficient and practical approach to synthesize functionalized phenanthridines from vinyl benzotriazoles with alkyl bromides under mild conditions. Significantly, the readily available and bench-stable vinyl benzotriazoles can serve as valuable alternative radical acceptors during the synthesis of phenanthridines.