Amorphous\nFe<sub>0.8</sub>Mn<sub>0.2</sub>O<sub><i>x</i></sub>‑Catalyzed\nFour-Step Tandem Synthesis of Benzazoles\nfrom Alcohols and o‑Substituted Anilines without Solvent

Benzazoles, as crucial intermediates, can be synthesized\nvia a\nsuperior four-step tandem catalytic process from benzyl alcohols and\no-substituted anilines. However, the reported catalysis system needs\ncomplex catalysts, toxoneic solvents, and additives; meanwhile, the\nefficient synthesis of benzimidazoles, benzoxazoles, and benzothiazoles\nusing a single catalyst represents a substantial challenge in the\nfield of synthetic chemistry. Herein, we constructed an amorphous\nFe<sub>0.8</sub>Mn<sub>0.2</sub>O<sub><i>x</i></sub>-300\ncatalyst by a simple coprecipitation method. Fe<sub>0.8</sub>Mn<sub>0.2</sub>O<sub><i>x</i></sub>-300 can efficiently catalyze\nthe four-step tandem synthesis of 2-arylbenzimidazole, 2-arylbenzoxazole,\nand 2-arylbenzothiazole from benzyl alcohol, o-phenylenediamine, 2-aminophenol,\nand 2-aminothiophenol, respectively, using O<sub>2</sub> without solvent\nand additives. Comprehensive characterization revealed that Fe<sub>0.8</sub>Mn<sub>0.2</sub>O<sub><i>x</i></sub>-300 possesses\nmore oxygen vacancies and stronger oxygen capture capability, promoting\nthe oxidation of alcohol and 2-aryl-2,3-dihydro-1<i>H</i>-benzimidazole. Due to its high density of acidic sites, Fe<sub>0.8</sub>Mn<sub>0.2</sub>O<sub><i>x</i></sub>-300 effectively boosts\nthe condensation and cyclization of aldehydes and amines while simultaneously\ninhibiting the formation of diamines, thereby enhancing the overall\nselectivity. Our work presents an alternative green approach for the\nindustrial synthesis of benzazoles.