First Isolation of Both Indolylcarbinols and Diindolylalkanes from Microwave-assisted Acid (Clay)-catalysed Reaction of Indoles with Diethyl Ketomalonate

Abstract

Indoles (la-f) react with diethyl ketomalonate on montmorillonite K10 clay under microwave irradiation to furnish expeditiously (1-4 min) the corresponding indol-3'-ylcarbinols (2a-f; 20-45%) and the respective diindolylalkanes (3a-f; 5-35%), which constitute the first direct evidence for the intermediacy of indolylcarbinols in the formation of diindolylalkanes from the acid-catalysed reaction of indoles with aldehydes and ketones.