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First synthesis of novel pentaheterocyclic ring system of 1,2,4‐triazolo[2″,3″:6′,1′]pyrimido[4′,5′:2,3]pyrido[1,2‐ a ]benzimidazole
Author(s) -
Elwan Nehal M.
Publication year - 2004
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570410222
Subject(s) - benzimidazole , chemistry , ethyl chloroformate , acetic anhydride , ring (chemistry) , hydrazine (antidepressant) , isothiocyanate , hydrate , medicinal chemistry , aryl , bicyclic molecule , stereochemistry , organic chemistry , catalysis , alkyl , chromatography
Reaction of 1‐amino‐3‐arylpyrido[1,2‐ a ]benzimidazole‐2,4‐dicarbonitrile (1) with dimethylformamide‐dimethylacetal (DMF‐DMA) gave 1 ‐[ N,N ‐(dimethylaminomethylene)amino]‐3‐arylpyrido[1,2‐ a ]benzimidazole‐2,4‐dicarbonitrile (2). Compounds (1) reacted with triethylorthoformate yielding 1‐[ N ‐(ethoxymethylene)amino]‐3‐arylpyrido[1,2‐ a ]benzimidazole‐2,4‐dicarbonitrile (3). 3‐Amino‐4‐imino‐5‐aryl‐6‐cyanopyrimido[5′,4′:5,6]pyrido[1,2‐α] benzimidazole (4) was synthesized via condensation of either (2) or (3) with hydrazine hydrate. Reactions of (4) with acetic anhydride, ethyl chloroformate or aryl isothiocyanate yielded the respective derivative of the new ring system namely 1,2,4‐triazolo[2″,3″:6′,1′]pyrimido[4′,5′:2,3]pyrido[1,2‐ a ]benzimidazole (5–7).