Photocatalyst-, metal- and additive-free regioselective radical cascade sulfonylation/cyclization of benzimidazole derivatives with sulfonyl chlorides induced by visible light

Herein, an environmentally friendly and practical protocol for the visible-light-triggered regioselective radical cascade sulfonylation/cyclization of unactivated alkenes towards the synthesis of polycyclic benzimidazoles containing the sulfone group has been developed. Notably, the control experiments demonstrated that a radical pathway was involved in this reaction, and a sulfonyl radical center was initially generated via self-homolysis of sulfonyl chloride upon irradiation. Moreover, this protocol features a wide substrate scope, high atom economy, and excellent regioselectivity, and is easy to scale up.

Automated summary

An environmentally friendly and practical method for the regioselective radical cascade sulfonylation/cyclization of unactivated alkenes under visible-light-triggered conditions has been developed. The method allows for the synthesis of polycyclic benzimidazoles containing the sulfone group. Control experiments confirmed the involvement of radical pathways and the initial generation of a sulfonyl radical center through the self-homolysis of sulfonyl chloride. This protocol offers a wide substrate scope, high atom economy, excellent regioselectivity, and ease of scalability.