| Abstract: | The interaction of condensed nitrogen-containing bridge systems with chloral has been studied and the high sensitivity of the reaction to the  -excess of the initial heteroaromatic system has been established. It has been shown that chloral is a convenient formylating agent for systems with a moderate -excess —imidazol,2-a]imidazole, 9H-imidazo1,2-a]benzimidazole, imidazo1,2-a]pyridine, imidazo1,2-a]naphtho2,3-d]imidazole. Heterocycles with a high -excess (indolizine, pyrrolo1,2-a]benzimidazole) form cyanine dyes under the action of chloral. Systems with a lowered -excess (1H-imidazo1,2-a]benzimidazole, imidazo1,2-a]quinoline, imidazo2,1-a]isoquinoline, imidazo1,2-a]perimidine, imidazo5,1-b]benzoxazole, imidazo1,2-a]benzothiazole, and imidazo1,2-a]pyrimidine) do not react with chloral in a neutral medium. However, in a number of cases their foraylation can be carried out in an acid medium.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 528–537, April, 1980. |
