Tautomeric structure of 1-Oxy-2-phenylbenzimidazole

The synthesis of 3-methyl-2-phenylbenzimidazole-1-oxide (VIII) has been accomplished. Consequently, it has been possible to establish the tautomeric structure of I as 1-hydroxy-2-phenylbenzimidazole (Ia). Contrary to recent observations on the parent 1-oxybenzimidazole (IV), I shows no tendency to exist as an N-oxide (Ib) in aqueous solution.