Visible-Light Excitation of BODIPYs Enables Self-Promoted Radical Arylation at Their 3,5-Positions with Diazonium Salts.

A metal- and additive-free photochemical strategy for the direct arylation of boron dipyrromethene dyes (BODIPYs) at their 3,5-positions is reported. The operationally simple approach occurs under illumination by visible light in the absence of any external photoredox catalyst. The chemistry is driven by the singlet excited state (1PS*) of BODIPYs upon visible-light absorption while successively triggering the formation of aryl radicals from aryl diazonium salts. Furthermore, a new type of indole-fused BODIPY with NIR absorption has also been synthesized for the first time.