Photochemically induced chloromethylation/cyclization of benzimidazole derivatives with CCl/CHCl.

Herein, it is reported that a series of trichloromethyl/dichloromethyl substituted benzimidazole derivatives have been synthesized by dechlorination of CCl/CHCl to form polychloromethyl radicals and cyclization with an unactivated olefin under a purple LED lamp. The protocol features a wide substrate scope, high atom economy, and excellent regioselectivity, and is easy to scale up.