<span style="font-size:21.0pt;mso-bidi-font-size:14.0pt">A facile synthesis of [1,2,4]triazino[<span style="font-size:22.0pt;mso-bidi-font-size:15.0pt;mso-bidi-font-style:italic">4<i>,</i>5<i>-a</i><span style="font-size:21.0pt;mso-bidi-font-size:14.0pt">]benzimidazoles, pyrazolo[5,1-<i style="mso-bidi-font-style:normal">c</i>]triazines), triazolo[5,1<i>-c </i>]triazines and pyrido[1<i>,</i><span style="mso-bidi-font-style:italic">2<i>-a </i>]benzimidazoles </span></span></span></span>

Abstract

202-209Triazino[4,5-a]benzimidazoles <b style="mso-bidi-font-weight: normal">4 and 9 have been obtained by coupling of arenediazonium chlorides with ethyl (1-ethoxycarbonyl)benzimidazole-2-acetate. Pyrazolo[5,1-c ]triazines 8a-c and triazolo[5,1-c ]triazines 8d have been synthesized via coupling of diazotized heterocyclic amines with ethyl benzimidazole-2-acetate 1. Ethyl benzimidazole-2-acetate 1 reacts with 1,1-dicyano-2-substituted ethenes 13 and 1-cyano- 1-ethoxycarbonyl- 2-substituted ethenes 17 to give pyrido[1,2-a ]benzimidazoles 14 and <b style="mso-bidi-font-weight: normal">23, respectively. Compound 14 can be converted to 16 by hydrogen peroxide. Structures of the newely synthesised compounds are confirmed on the basis of elemental analyses, spectral data and alternative methods whenever possible.</span