OXIDATIVE CYCLIZATION OF 2-AMINO-1-ARYLIDENEAMINOBENZIMIDAZOLES INTO 1,2,4-TRIAZOLOBENZIMIDAZOLES

Article abstract of DOI:10.1007/BF00474046

When heated in nitrobenzene, 1-arylideneamino-2-methylaminobenzimidazoles convert in a 20...30percent yield into 2-aryl-3-methyl-1,2,4-triazolo<1,5-a>benzimidazoles.In addition, 2-methylaminobenzimidazole and the corresponding benzonitrile are formed as a result of thermal splitting of the N-N bond.Under the same conditions, 2-amino-1-arylideneaminobenzimidazoles and 1-arylideneamino-3-methylbenzimidazoline-2-imines give only products of splitting off of the nitrile.In several cases, the subsequent reaction of the nitrile with 2-amino-1-methylbenzimidazole leads to the formation of benzamidines.