Camphor sulfonic acid catalyzed a simple, facile, and general method for the synthesis of 2-arylbenzothiazoles, 2-arylbenzimidazoles, and 3H-spiro[benzo[d]thiazole-2,3′-indolin]-2′-ones at room temperature

Abstract

A simple, mild, eco-friendly, general, and convenient approach has been developed for the synthesis of structurally diverse 2-arylbenzothiazole derivatives from the reactions of 2-aminothiophenol and various aromatic aldehydes using camphor sulfonic acid a low cost, commercially available, efficient organo-catalyst in aqueous ethanol at room temperature. Under the same optimized conditions, a series of 2-arylbenzimidazoles was also synthesized starting from o-phenylenediamines and various aldehydes whereas synthesis of 3H-spiro[benzo[d]thiazole-2,3′-indolin]-2′-ones was accomplished from the reactions of 2-aminothiophenol and substituted isatins.

Graphical Abstract

Keywords:

• 2-arylbenzimidazoles
• 2-arylbenzothiazoles
• camphor sulfonic acid
• 3H-spiro[benzo[d]thiazole-2,3′-indolin]-2′-ones
• organocatalysis

Acknowledgments

Dr. B. Banerjee is thankful to the Indus International University, Una, Himachal Pradesh, India and the Kartha Education Society, Mumbai, India for the support. The authors are grateful to AMRC, IIT Mandi, Himachal Pradesh, India for the spectral measurements such as ¹H and ¹³C NMR and HRMS data.