SYNTHESIS OF SOME NEW BENZIMIDAZOLE-5(6)-CARBOXYLIC ACIDS

The title compounds, 1,2-dialkyl-benzimidazole-5(6)-carboxylic acids 3 4-45 were prepared at four steps; 1) preparation of mono amide derivat ives 1-11 by the reaction of methyl 3,4-diaminobenzoate and substitute d phenyl or phenoxyacetic acid chlorides; 2) preparation of the methyl benzimidazolecarboxylates 12-22, with zinc chloride and dry hydrogen chloride gas; 3) alkaline hydrolysis of the esters 23-33; and 4) subst itution of the imidazole ring with benzyl or p-fluorobenzyl bromide, i n alkali medium. 2-Aryl-benzimidazole-5(6)-carboxylic acids 50-53 were prepared via the oxidative condensation of 3,4-diaminobenzoic acid an d aromatic aldehydes with cupric ion.