Benzoic Acid → 2-Methylbenzimidazole

Participants

Reaction Steps

Preparation of the intermediate benzoic acid 2 is shown in Scheme 2. 1,2-phenylenediamine is condensed with acetic anhydride to form 2-methylbenzimidazole which is then reacted with benzyl halide 5 (where X is Br, Cl, I, methansulfonyl, or p-toluenesulfonyl), in the presence of base to form 6. Hydrolysis of ester 6 gives benzoic acid 2. Condensation of 3,4-diaminopyridine with acetic anhydride followed by reaction with benzyl halide 5 as described above gives a mixture of 1-, 3-, and 5-substituted imidazo[4,5-c]pyridines (compounds 8, 9, and 10) which are separated by chromatography on silica gel and convened to 2 as described above. Similarly, imidazo[4,5-b]pyridines 12, 13, and 14 are prepared from 2,3-diaminopyridine. ##STR10##

Provenance & Evidence