Studies on regioselectivity of nitration of coumarins with cerium (IV) ammonium nitrate: Solid-state nitration of 6-hydroxy-coumarins on montmorillonite K-10 clay …
Abstract 6-Hydroxycoumarins and their O-methyl ethers were selectively nitrated in the carbocyclic ring even in the presence of activating 4-Me group in the 2-pyrone ring with cerium (IV) ammonium nitrate (CAN) in acetic acid and acetonitrile in acceptable-to- excellent yields. Acetonitrile was found to be a better solvent for regioselective nitration than acetic acid. Use of CAN on montmorillonite K-10 clay under microwave irradiation for ...