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1,2,3‐benzotriazines. I. The synthesis of some benzimidazo [1,2‐c][1,2,3]‐benzotriazines and naphth[1′,2,(2′,1′):4,5]imidazo[1,2‐c][1,2,3]benzotriazine
Author(s) -
Zaika Laura L.,
Joullié Madeleine M.
Publication year - 1966
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.5570030311
Subject(s) - chemistry , nitrobenzene , benzimidazole , imidazole , acetic acid , acetic anhydride , hydrochloric acid , anthranilic acid , o phenylenediamine , condensation , medicinal chemistry , organic chemistry , catalysis , salt (chemistry) , aldehyde , formaldehyde , physics , thermodynamics
A number of substituted benzimidazo[1, 2‐c][1,2,3]benzotriazines were prepared by the diazotization of the appropriate 2‐( o ‐aminophenyl)benzimidazoles. Diazotization of 2‐( o ‐aminophenyl)naphth[1,2‐d]imidazole yielded a new heterocyclic ring system. Various methods of preparation of 2 ‐ ( o ‐aminophenyl)benzimidazoles were investigated. The condensation of o ‐phenylenediamines with anthranilic acids, in the presence of polyphosphoric acid, provided a convenient route to 2‐( o ‐aminophenyl)benzimidazoles but in several cases the products were contaminated with considerable amounts of 6‐( o ‐aminophenyl)benzimidazo[1,2 ‐c]quinazolines. 2 ‐ ( o ‐Aminophenyl)benzimidazoles were also obtained by the catalytic hydrogenation of 2‐( o ‐nitrophenyl)benzimidazoles which resulted from the condensation of an o ‐phenylenediamine with an o ‐nitrobenzaldehyde in ethanol, nitrobenzene or acetic acid. When the condensation was carried out in nitrobenzene, small amounts of 2‐( o ‐aminophenyl)benzimidazoles were also formed. The Weidenhagen synthesis, which involves the reaction of an aromatic diamine with an aldehyde in the presence of copper acetate and subsequent decomposition of the cuprous salt of the benzimidazole, yielded 2‐( o ‐aminophenyl)benzimidazoles instead of the expected 2‐( o ‐nitrophenyl)benzimidazoles when the decomposition was carried out in ethanol. When the cuprous salt was treated with hydrogen sulfide in dilute hydrochloric acid, a mixture of amino‐ and nitrobenzimidazoles resulted. The ultraviolet and infrared spectra of all the compounds prepared were examined.