First General Solvent‐Free Synthesis of Symmetrical Triindolylmethanes Using Acid‐Washed Montmorillonite Clay

Abstract

Dry reaction of indoles and alkylindoles (1a–h) with triethyl orthoformate (2.5 equiv.) on acid‐washed montmorillonite K10 clay at room temperature afforded in <5 min–4 hr the respective symmetrical TIMs (2a–h) in good to high yields along with the formylindole 3 and the formyl‐TIM 4 from 1g and 1h, respectively.

Keywords:

• Triindolylmethanes
• Solvent‐free synthesis
• Acid‐washed montmorillonite clay
• Orthoester

Acknowledgments

The authors sincerely thank the Director, Bose Institute for laboratory facilities, the C.S.I.R., Govt. of India for providing fellowship (S.S.), Prof. Y. Harigaya, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan, Mr. B. Majumder, NMR Lab., Mr. J. Chatterjee, R.S.I.C. and Mr. P. Dey, Microanalytical Lab., all of B.I., for recording the spectra.