Synthesis of the first nanomagnetic particles with semicarbazide-based acidic ionic liquid tag: an efficient catalyst for the synthesis of 3,3′-(arylmethylene)bis(4-hydroxycoumarin) and 1-carbamato-alkyl-2-naphthol derivatives under mild and green conditi

Greener Syntheses of Coumarin Derivatives Using Magnetic Nanocatalysts: Recent Advances

Coumarins (2H-1-benzopyran-2-ones) are an important group of biological heterocyclic compounds present in various parts of many plant species, encompassing an array of biological and pharmaceutical activities. In view of the importance of coumarins in heterocyclic chemistry and biological sciences and recent advances in the design of magnetic nanocatalysts, we present herein recent developments pertaining to their synthesis exclusively using magnetic nanoparticles, which can be retrieved easily and thus conform to the tenets of greener synthesis. The preparation of various types of coumarins such as Pechmann-based coumarins, bis coumarins, pyranocoumarins, and coumarin derivatives bearing amine moiety, linked to nicotinonitriles, N-coumarin-2-furanone, and pyrrole-linked chromene derivatives using nanocatalysts with a Fe₃O₄ core are described. This review covers the synthetic developments in the recent years 2012-2021 and focuses entirely on the synthesis of coumarins in the presence of magnetic nanocatalysts using greener approaches such as solvent-free conditions or deploying alternative activation methods, namely microwave or ultrasound irradiation.

One-Pot Multicomponent Reaction of Catechols, Ammonium Acetate, and Aldehydes for the Synthesis of Benzoxazole Derivatives Using the Fe(III)-Salen Complex

The Fe(III)-salen complex has been applied successfully as a catalyst for the novel, simple, efficient, and one-pot multicomponent synthesis of benzoxazole derivatives from catechols, ammonium acetate as the nitrogen source, and aldehydes (nontoxic and cheap alternatives of amines) for the first time. Using this procedure, a wide range of benzoxazoles was successfully synthesized in the presence of a catalyst in EtOH under mild conditions, and all products were obtained in excellent yields. To the best of our knowledge, this method is the first example of the multicomponent synthesis of benzoxazole derivatives using these starting materials. The notable features such as the use of air that is considered as a benign oxidant and EtOH as a green solvent, ease of product separation, readily available and inexpensive aldehydes, and mild conditions make our procedure more efficient and practical for organic synthesis. Moreover, the current protocol is successfully applied to synthesize desirable products on a large scale.

Synthesis of unexpected novel bis-coumarin derivatives three component reactions of 4-hydroxycoumarin, aldehydes and cyclic secondary amines. Conformation in the solid state and pharmacological evaluation

A series of unexpected bis-coumarins have been synthesized by multicomponent reactions of 4-hydroxycoumarin, aldehydes, and cyclic secondary amines in ethanol at room temperature. The chemical structures of new compounds were identified by 1H, 13C NMR, and mass spectrometry. Furthermore, the molecular structure of the solid-state adduct of 3,3′-[(4-methoxyphenyl)-methylene]bis(4-hydroxy-2H-chromen-2-one) with morpholine (1:1) has been confirmed by single-crystal X-ray diffraction. The cytotoxicity of the new coumarin derivatives against MCF7 breast cancer cells was evaluated. A docking study of the new products was carried out to assess the molecular affinity between the tested compound and Topoisomerase IIa.

Application of biological-based nano and nano magnetic catalysts in the preparation of arylbispyranylmethanes

Nano 2-carbamoylhydrazine-1-sulfonic acid, carbamoylsulfamic acid and their related nano magnetic core–shell catalysts as biological-based nano catalysts with a urea moiety were used in the synthesis of arylbispyranylmethanes.