The Study On The Synthesis Of Heterocyclic Compounds Such As Pyridine,Pyran And Pyrazole Derivatives Catalyzed By Deep Eutectic Solvents

Recently,a new class of Ionic Liquids(ILs)-analogue called Deep Eutectic Solvents(DESs)has been widely studied.DES is a fluid generally composed of two or more 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.Deep eutectic solvents(DESs)have received much attention because of their favorable properties of nonvolatility,thermal stability,water compatibility,biocompability,biodegradability,and diversity of ionic structures.Therefore,in this paper,a variety of heterocyclic compounds are greenly and efficiently synthesized using DESs as catalysts.The specific contents are as follows:1.The application of DESs as catalysts in organic synthesis in recent years were summarized.2.An efficient and facile procedure for the synthesis of 2-amino-2-chromenes derivatives has been developed by condensation of aldehyde with malononitrile and1-naphthol in aqueous ethanol,using DES(Ch Cl/urea 1:2)as catalyst.All compounds were synthesized with a yield of 86-94%.The structure of part of the product was characterized by IR and ¹H NMR.3.The formation of DESs results from strong hydrogen bond interactions between hydrogen bond acceptors and hydrogen bond donors.It is well known that environmentally-friendly ethanol was protonic polar solvent and we speculate that it could also play the role of hydrogen bond donor.The combination of choline chloride and protonic polar solvent would generate catalytic active species too.A total of 17 acridine-1,8-dione derivatives(yields of 79-98%yield)were synthesized by a three-component one-pot approach of aldehydes with dimedone and ammonium acetate.Inspired by the catalytic potential of choline chloride,we replaced the substrate from dimedone to ethyl acetoacetate and repeated the reaction with the same substituted aldehydes.17 polyhydroquinoline derivatives were synthesized with a yield of 72-97%.The structure was characterized by IR,¹H NMR and ¹³C NMR.4.A one-pot three-component reaction used phenylhydrazine,aldehyde and malononitrile as raw materials,and the synthesis method was developed.13 pyrazole derivatives with yields of 81-96%were obtained by optimizing the reaction conditions.The structure of part of the product was characterized by IR and ¹H NMR.