Irradiation of hydrazines with visible-light in the presence of organic dye eosin B generates various types of functional radicals, which are trapped by 2-isocyanobiphenyls to give 6-substituted phenanthridines.
A metal-free radical oxidative decarboxylation/cyclization of acyl peroxides and 2-isocyanobiphenyls was achieved, leading to 6-aryl phenanthridines as well as 6-alkyl phenanthridines in moderate to good yields. The procedure featured simple conditions and was metal-free and base free. It represents a practical approach to access 6-aryl/alkyl phenanthridines.