Abstract
1-Methylbenzimidazole 3-oxide reacted with phenyl isocyanate, phenyl isothiocyanate, dimethyl acetylenedicarboxylate, and methyl propiolate, at room temperature and with benzonitrile, phenyl isocyanide, and benzyne on heating to give 1-methyl-2-anilino-benzimidazole (II), II, dimethyl 1-methyl-2-benzimidazoloxalacetate, methyl α-formyl-1-methyl-2-benzimidazolacetate, 1-methl-2-benzamidobenzimidazole, II, 1-methyl-2-(ο-hydroxyphenyl) benzimidazole, respectively. Although the initial cycloadducts could not be isolated, these reactions can be best explained as occurring via 1, 3-dipolar cycloaddition.
