Access to N-thioalkenyl and N-(o-thio)aryl-benzimidazol-2-ones by ring opening of thiazolobenzimidazolium and benzimidazobenzothiazolium salts and C-O bond cleavage of an alkoxide.

We report herein the synthesis of highly functionalized 1,3-dihydro-2H-benzimidazol-2-ones via a ring opening of thiazolo[3,2-a]benzimidazolium or benzimidazo[2,1-b][1,3]benzothiazol-6-ium salts and an unusual C-O bond cleavage of an alkoxide. A large variety of benzimidazolones bearing an original N-thioalkenyl or N-(o-thio)aryl group was obtained in high yields. The developed chemistry provides efficient and rapid access to the privileged benzimidazol-2-one scaffold.