Solid‐State Regioselective Cyclization Initiated by the Electrophilic Attack on the Double Bond by N‐Bromosuccinimide on Montmorillonite K‐10 Clay Support under Microwave Irradiation

Abstract

3‐Allyl‐4‐hydroxy‐coumarins and pyrones were regioselectively cyclized with N‐bromosuccinimide (NBS) on solid phase under microwave irradiation in excellent yield. NBS on montmorillonite K‐10 clay under microwave irradiation for expeditious solvent‐free regioselective cyclization has been used for the first time.

Keywords:

• 6‐endo cyclization
• 4‐hydroxy coumarin
• 4‐hydroxy pyrone
• microwave irradiation
• N‐bromosuccinimide
• solid‐state reaction

Acknowledgment

This work is financially supported by Council of Scientific and Industrial Research (CSIR) (New Delhi). One of us (H. R.) is very grateful to the University of Kalyani for providing a fellowship.