A facile one pot synthesis of 1-alkylbenzimidazoline-2-thiones

Reactions of benziraidazoline-2-thione with alkyl halides in the presence of sodium naphthalenide in tetra-hydrofuran at room temperature under a nitrogen atmosphere afforded 1-alkyl-2-alkylthiobenzimidazoles in excellent yields, which underwent a bond cleavage between S and C of alkyl group to give excellent yields of 1-alkylbenzimidazoline-2-thiones by the treatment with an additional amount of sodium naphthalenide.