In our research, quantum chemical calculations of the ability of osubstituted aromatic amines to react with urea were carried out in the SPK-DZP basis set of the GAMESS program, and compared with experimental results, the range of amines' reactivity, mechanism and relative activity was proposed. As a result of the reaction, synthesis of benzimidazolin-2-one, benzoxazolin-2-one, and benzothiazolin2-one was carried out.