Condensed imidazo-1,2,4-azines. 21. Synthesis of 2-arylfuro(pyrrolo-, thieno-)[2,3-e]-1,2,4-triazino[2,3-a]benzimidazoles by cyclization of 2-aroyl-1,2,4-triazino[2,3-a]benzimidazol-4H-3-ones

✍ Scribed by V. P. Kruglenko; V. P. Gnidets; N. A. Klyuev; M. V. Povstyanoi

• Publisher: Springer US
• Year: 1989
• Tongue: English
• Weight: 352 KB
• Volume: 25
• Category: Article
• ISSN: 0009-3122
• DOI: 10.1007/bf00479615

✦ Synopsis

UDC 547.873'785.5'735 f 724.07:543.51 2-[(8-Ethyl-, arylimino)phenethyl]-l,2,4-triazino[2,3-a]benzimidazoles were obtained by reaction of 2-aroylmethyl-l,2,4-triazino[2,3-a]benzimidazol-4H-3-ones with ethyl(aryl)amines or urea. By the action of phosphorus oxychloride, these benzimidazoles cyclize into substituted pyrrolo[2,3-e]-l,2,4-triazino[2,3-a]benzimidazoles, heating of which in polyphosphoric acid leads to the formation of furo[2,3-e]-l,2,4-triazino[2,3a]benzimidazoles, while by the action of P4SI0, they are transformed into thieno[2,3-e]-l,2,4-triazino[2,3-a]benzimidazoles.

We have already reported [2] that 2-phenylfuro[2,3-e]-l,2,4-triazino[2,3-a]benzimidazole (lla) is formed by boiling 2-benzoylmethyl-l,2,4-triazino[2,3-a]benzimidazol-4H-3one (la) in phosphorus oxychloride with PCI s. Extending the research in this direction, in order to synthesize new luminescing heterocyclic compounds, we studied the reaction of aroylmethyl derivatives la-d with ethyl(aryl)amines, urea, and phosphorus pentasulfide.