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

Abstract

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.