A green synthesis of symmetrical bis(indol-3-yl)methanes using phosphate-impregnated titania catalyst under solvent free grinding conditions

Abstract

An efficient, chemoselective method for the preparation of bis(indol-3-yl)methanes from aldehydes and indoles using phosphate-impregnated titania as the reusable catalyst under solvent-free grinding conditions is reported. The desired products were obtained in excellent yields with tolerability to functional groups such as −OMe, −Me, −Cl, −NO₂, and −OH in a simple and environmentally benign procedure.

Keywords:

• bis(indol-3-yl)methanes
• aldehydes
• green chemistry
• phosphate-impregnated titania
• solvent free
• grinding

Acknowledgements

Ashim Jyoti Thakur thanks Council of Scientific and Industrial Research (CSIR), New Delhi, India for financial support to the project CSIR (01(2147)/07/EMR-II) and Prof. MK Chaudhari, Vice Chancellor, Tezpur University for helpful discussions. Dhrubajyoti Talukdar thanks Tezpur University for the institutional fellowship.