Seralite SRC-120 resin catalyzed synthesis of bis(indolyl)methanes using indoles and low/high boiling point carbonyl compounds under solvent free conditions

Abstract

A highly inexpensive, and operationally simple seralite SRC-120 (strongly acidic cation exchange resin) catalyzed synthesis of 3,3′-bis(indolyl)methanes (BIMs) from indoles and low/high boiling point carbonyl compounds under solvent-free condition is reported. Synthesis of BIMs with low boiling point carbonyls at room temperature takes prolonged reaction time and give low yields at high temperature. The reported method overcomes these limitations and works remarkably well with low/high boiling point aldehydes/ketones in shorter reaction times (5–10 min) under microwave irradiation conditions and provides moderate to excellent yields (65–94%). Moreover, the recyclability of the catalyst for at least five times without notable loss in activity makes the whole process attractive and green protocol.