Synthesis of 1,3‐dihydro‐2H‐benzimidazol‐2‐one from 2‐aminobenzamide

A method for the synthesis of 2‐henzimidazolone (1) has been devised which does not depend on 1,2‐diaminobenzene (2) as a starting material. This method produces 1 in good yield by the reaction of hypohalite with 2′‐carbamoylphthalanilic acid (7), a compound readily prepared by the reaction of 2‐aminobenzamide (3) and phthalic anhydride. Contrary to prior indications 1 can be hydrolyzed in the presence of acid at temperatures greater than 200 giving excellent yields of 2.