Synthesis of Ni@C as a Magnetic Heterogeneous Catalyst: Application to Benzimidazoles and Quinoxalines from o-Phenylenediamines with Primary Amines

Herein, we report a simple and straightforward magnetic heterogeneous catalytic (Ni@C) approach to synthesize benzimidazole and quinoxaline scaffolds from o-phenylene diamines with primary amines using H2O as an environmentally benign solvent. The Ni@C catalyst was synthesized using a pyrolysis method and unambiguously analyzed by various characterization techniques. The scope of the catalytic methodology was presented with various o-phenylene diamines and primary amines producing a range of benzimidazoles and quinoxalines in good to excellent yields. The notable feature include reusability of the Ni@C catalyst (up to five cycles), synthetic applications to functionalize -NH proton of 1H-benzimidazole and the gram-scale synthesis which could be a potential industrial application.