Visible-light-driven eosin Y catalyzed arylation of alkenes with formate salt.

A visible-light-driven metal-free method for the arylation of alkenes with aryl iodides and formate salt has been developed. The reaction exhibited a broad substrate scope for both α,α-disubstituted alkenes and diversely substituted aryl iodides. Combined experimental and computational mechanistic studies highlighted the essential role of the carbon dioxide radical anion (CO2˙-) in the transformation. This mild photocatalytic strategy provides practical access to valuable arylated alkene products.