2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is a commonly known oxidant. Herein, we report that DDQ can be used to synthesize 1,2-disubstituted benzimidazoles and quinazolin-4(3H)-ones via the intra- and intermolecular C–N coupling reaction under solvent-free mechanochemical (ball milling) conditions. In the presence of DDQ, the intramolecular C(sp2)–H amidation of N-(2-(arylideneamino)phenyl)-p-toluenesulfonamides leads to 1,2-disubstituted benzimidazoles and the one-pot coupling of 2-aminobenzamides with aryl/alkyl aldehydes resulted in substituted quinazolin-4(3H)-one derivatives in high yields.

Herein, we demonstrate a regioselective intramolecular C-N cross-coupling for the synthesis of 14H-quinazolino[3,2-f]phenanthridin-14-one by using 9-mesityl-10-methylacridinium perchlorate as the visible-light (450-470 nm) photocatalyst. The experiments with BHT, TEMPO, and Stern-Volmer...

Use of sustainable energy sources in synthetic organic chemistry has become one of the popular research topics, due to environmental pollution and global warming. In this review, we have made a collection of literature that covers photocatalyst-free and transition metal-free light-induced reactions for the construction of carbon-carbon (C-C) bonds. The reaction systems discussed here are C-C bond formation via carbene intermediate, radical intermediate, and miscellaneous illustration via cyclization.

This manuscript presents a useful method for the formation of benzimidazole-fused phenanthridines through an intramolecular coupling of unactivated C(sp2)-H and N(sp3)-H bonds using N-iodosuccinimide (NIS) in trifluoroethanol (TFE). The synthesis of benzo[4,5]imidazo[1,2-f]phenanthridines from 2-([1,1'-biphenyl]-2-yl)-1H-benzo[d]imidazole derivatives describes as mild, efficient, and sustainable, with high yields and minimal waste generation. The control experiments and EPR studies aimed at rationalizing the radical pathway of the reaction. Specifically, the use of 1,1-diphenylethylene, TEMPO, BHT, and DMPO as a free-radical spin-trapping reagent in EPR studies, allowed us to conceive a radical pathway. The gram-scale synthesis further supported the practical utility of the methodology for the field of synthetic chemistry.