Photo-induced direct C(sp²)-H bond azo coupling of imidazo-heteroarenes with aryl diazonium salts

Herein, we report a greener protocol for the C(sp2)-H bond azo coupling of imidazo-heteroarene with aryl diazonium salts, catalyzed by eosin Y, under acid free conditions. This direct photoredox, eco-friendly and efficient approach afforded the desired products in good to excellent yields. The key features of this protocol are that it provides high yields and is atom-economic, gram-scalable and applicable to biologically relevant imidazo-heteroarenes.