CO2-promoted photoredox-catalyzed cascade cyclization of N-propargylindoles with sulfinates

Simultaneous incorporation of a sulfonyl group and a tricyclic indole framework within a single molecular might yield structural motifs commonly found in bioactive compounds. Herein, we present a CO 2 -promoted photoredox-catalyzed cascade cyclization strategy to construct new sulfonated tricyclic indole skeletons from N -propargylindoles and sulfinates. This methodology operates efficiently at ambient temperature without requiring external oxidants, exhibiting broad functional group compatibility as demonstrated by more than 50 diverse examples. Crucially, abundant, nontoxic and low-cost CO 2 has been proved to be an important additive in this sulfonyl radical involved cyclization pathway. This strategy leverages renewable CO 2 , visible light, and oxidant-free conditions to minimize environmental footprint, enabling sustainable synthesis of sulfonated heterocycles. Herein, we present a CO 2 -promoted photoredox-catalyzed cascade cyclization strategy to construct new sulfonated tricyclic indole skeletons without requiring external oxidants. Crucially, abundant, nontoxic and low-cost CO 2 is proved to be an important additive in this sulfonyl radical involved cyclization pathway.