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Abstract
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There is pressing need to replace hazardous and harmful solvents with “green” or “sustainable” media. A new generation of solvent, named Deep Eutectic Solvents (DESs), has recently emerged as an alternative green reaction media.1-2 A DES is a fluid generally composed of two or three cheap and safe components that are capable of self-association, often through hydrogen bond interactions, to form a eutectic mixture with a melting point lower than that of each individual component. Thanks to their low ecological footprint and attractive price, DESs have now become of growing interest both at academic and industrial levels.
Pyrazolone is a subunit of many biologically active compounds. Drugs incorporating this unit have been a continuous source of known anti-anxiety, antiinflammatory, antipyretic, analgesic, anti-depressant, anticonvulsant and hypnotic agents. Condensed pyrazoles, on the other hand, are equally significant.3
The 1,4-dihydropyridine nucleus serves as the scaffold for important cardiovascular drugs, which exert their antihypertensive and antianginal actions through actions at voltage-gated calcium channels of the CaV1 (L-type) class.4
Dihydropyrimidinones, the products of the Biginelli reaction, are widely used in the pharmaceutical industry as calcium channel blockers, antihypertensive agents, and alpha-1-a-antagonists.5
Herein, we report a facile and environmentally benign multicomponent synthesis of pyrazole based compounds I, II, and Hantzsch esters III, IV and Biginelli dihydropyrimidinones V in different DESs. The structure of the products characterized by x-ray crystallography and IR, 1H, and 13C NMR spectroscopy. We also synthesized novel DES.
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