Visible-Light-Promoted Cascade Carboxylation/Arylation of Unactivated Alkenes with CO 2 for the Synthesis of Carboxylated Indole-Fused Heterocycles.

Described here is a visible-light-promoted cascade carboxylation/arylation of indole-tethered unactivated alkenes with CO 2 to access various carboxylated indole-fused heterocycles. This reaction is initiated by the addition of a CO 2 radical anion to the alkene motif toward an alkyl carbon radical, followed by its addition to the aromatic ring, and then rearomatization to afford the final products. This reaction provides a facile and sustainable protocol for the construction of carboxylated indole-fused heterocycles using CO 2 as the carboxylic source.