Abstract
New Bronchodilators - 2 : Synthesis Of 6-Alkylbenzimidazo [1,2-C] Quinazolines
Synthesis of 6-alkylbenzimidazo[l,2-c]quinazolines (4) has been investigated based on the cyclization of the 2-(2-aminophenyl) benzimidazoles (3) by refluxing with appropriate aliphatic acid anhydrides. The intermediates (3) were in turn obtained from two routes; a dehydrocyclization of different anthranilic acids (1) (Method A) and isatoic anhydrides (2) (Method B) with o-phenylenediamine. Attempts were also made to synthesize the title compounds using 2-alkyl3,1-benzoxazin-4-one as starting materials. Since most of the 2-alkylbenzoxazinones were unstable, yields obtained by this route were low. The title compounds (4) were characterized on the basis of their elemental analyses and spectral (IR, 1H-NMR and Mass) data. The bronchodilatory activity of compounds 4a and 4b is reported using in vitro and in vivo animals models.
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