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The Prelude of Green Syntheses of Drugs and Natural Products
Published in Ahindra Nag, Greener Synthesis of Organic Compounds, Drugs and Natural Products, 2022
Leonardo Xochicale-Santana, C. C. Vidyasagar, Blanca M. Muñoz-Flores, Víctor M. Jiménez Pérez
Under solvent-free microwave irradiation conditions, the group demonstrated a novel technique based on the Pechmann condensation, catalyzed by FeF3 as an efficient eco-friendly catalyst, for the synthesis of substituted coumarins. The related coumarins were obtained in moderate to high yields. One-pot synthesis, experimental simplicity under solvent-free microwave irradiation, high yields obtained in short reaction times, and simple and fast product isolation are all advantages of this process. The bulk of the compounds had strong efficacy against a variety of bacteria and fungi, with inhibition areas that were almost identical to those of normal medicines. As a result, a new class of compounds has been discovered that has antimicrobial potency equal to certain already used commercial bactericides/fungicides (Scheme 15.29).86
Luffa as a lignocellulosic material for fabrication of a new and green catalyst in promoting of coumarin and bis(indolyl)methane derivatives
Published in Green Chemistry Letters and Reviews, 2020
Ali Kazemi Tabrizi, Habibollah Khademieslam, Amir Hooman Hemmasi, Behzad Bazyar, Sayyed Vahid Atghia
The best procedure for the preparation of coumarins is the one-pot condensation of various phenols with ethyl acetoacetate, which is known as Pechmann condensation. Some of the new reagents in synthesis of coumarins include; Ag supported on hydroxyapatite (HAp)-core–shell magnetic γ-Fe2O3 (γ-Fe2O3@HAp-Ag) (47), ammonium hydrogen sulfate supported sugarcane bagasse (AHS@CSCB) (48), magnetic nanoparticles functionalized ethane sulfonic acid (MNESA) (49), 1,1´-butylenebispyridinium hydrogen sulfate (50), ammonium hydrogen sulfate based ionic liquid immobilized on Na+–montmorillonite (AHS@MMT) (51), (±)-camphor-10-sulfonic acid (52), choline chloride/zinc chloride (ChCl.2ZnCl2) (53), zirconia-based heterogeneous catalysts (54). These protocols are useful, but some aspects of green chemistry have not been observed. For example, energy consumption for the preparation of γ-Fe2O3@HAp-Ag is high (some steps of catalyst preparation require 300 °C for 6 h) and the reaction times in the case of zirconia-based catalyst are long (20–170 min). Therefore, presenting new and green methods for coumarin synthesis is still one of the concerns of organic chemists.