Various coumarin derivatives have been efficiently synthesized via barium dichloride-catalyzed Pechmann condensation reaction of various phenols and β-keto esters under solvent-free conditions. This novel and inexpensive method has advantages such as short reaction times, excellent product yields, and avoidance of organic solvents in agreement with green chemistry principles.
A nitro coumarin derivatives has been synthesized via nitration of 7-hydroxy-4-methyl coumarin wich was synthesized via Pechmann condensation resorcinol with a β-ketoester using Amberlyst-15 as a green and efficient catalyst and by caring out the reaction of resorcinol and ethyl acetoacetate (with 1: 1 mol ratio) in the presence of 0.2 g of Amberlyst-15 at 110°C under solvent-free conditions. These nitro coumarin derivatives have biological activity and momentousness in the industrial fields. The purified products were measured the melting points and characterized by spectral methods: FT-IR,1H-NMR ,13C-NMR.
A new and efficient condition for the use of alumina sulfuric acid (ASA) as a heterogeneous catalyst in the Pechmann condensation reaction in solvent-free condition for the formation of coumarins has been reported.
Barium Dichloride as a Powerful and Inexpensive Catalyst for the Pechmann Condensation without Using Solvent