Rare-Earth Metal Chlorides as Efficient Catalysts for the Simple and Green Synthesis of 1,2-Disubstituted Benzimidazoles and 2-Substituted Benzothiazoles Under Ultrasound Irradiation

Abstract

Under solvent-free and ultrasonic irradiation conditions, efficient methods for the synthesis of 1,2-disubstitued benzimidazoles and 2-substitued benzothiazoles by employing rare-earth metal chlorides as catalysts are described. The methods have the advantages of broad generality, economical catalysts, good yields, simple operation, solvent-free condition, and ambient temperature.

GRAPHICAL ABSTRACT

Keywords:

• Benzimidazole
• benzothiazole
• catalysis
• rare-earth metal
• ultrasound

ACKNOWLEDGMENTS

The work was supported by the National Natural Science Foundation of China (20702001 and 20832001) and the Anhui Education Department (TD200707 and KJ2007A011).

Notes

^a Benzaldehyde/o-phenylenediamine.

^b Isolated yield.

Condition: Reaction of o-phenylenediamine with benzaldehyde under the optimum conditions.

^a Isolated yield.