One-pot synthesis of 2-(1-alkyl/aralkyl-1H-benzimidazole-2-yl)-quinoxaline derivatives using molecular iodine

The title compound (5) has been prepared in one pot by refluxing 1-(1-alkyl/aralkyl-1H-benzimidazole-2-yl)-ethanone (1) with substituted o-phenylenediamine (2) in ethanol in the presence of iodine. Alternatively, 5 could also be prepared by treating 2-bromo-1-(1- alkyl/aralkyl-1H-benzimidazole-2-yl)-ethanone (3A) with 2 in refluxing ethanol. The formation of 5 from 1 and 2 probably occurs through the intermediacy of 3B (i.e., 3, X=I) and 4.