Studies On Ionic Liquid Catalyzed Multicomponent Reactions In The Synthesis Of Heterocyclic Compounds Containing A Pyrazole Or Pyridine Moiety

In this dissertation, much attention has been focused on the MCRs in the synthesis of heterocyclic compounds containing a pyrazole or pyridine moiety in the presence of task-specific ionic liquids. The whole work is mainly composed of following three parts:The first part is about the synthesis of heterocycles containing a pyrazole moiety. A facile route to synthesis of1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives via a basic ionic liquid [H3N+CH2CH2OH][CH3COO-](HEAA) catalyzed one-pot, three-component condensation of phthalhydrazide, aldehydes, and phenylsulfonylacetonitrile or malononitrile at room temperature is reported. The advantages of this method include atom-efficient, easy work-up, excellent yields and environmental friendliness. The photophysical properties for some1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives have also been investigated. The result suggests that phenylsulfonyl group in1H-pyrazolo[1,2-b]phthalazine-5,10-diones might be the crucial factors to affect the high photostability.The second part studies an efficient strategy for the synthesis of1,4-DHPs.A practical and efficient procedure for the preparation of the polysubstituted dihydropyridines is developed through a unique four-component reaction of aromatic aldehydes or isatins, malononitrile or phenylsulfonylacetonitrile, primary amines, and acetylenic esters in ethanol in the presence of [bmim]OH as a catalyst at room temperature. The process has many advantages such as high yield, available raw materials, mild reaction conditions, convenient procedures, environmental friendliness, Besides, the ionic liquid [bmim]OH is successively recovered and recycled up to six times without any loss and diminution in its amount and efficacy.The third part illustrates the synthesis and characterization of pyrazolo[4,3-e]pyridine derivatives. A facile route to synthesis of novel Dihydrochromeno[2,3-b]pyrazolo[4,3-e]pyridin-5(1H)-ones via a sulfonic acid ionic liquid [Hnmp]HSO4catalyzed one-pot, three-component condensation of aldehydes,4-Hydroxycoumarin, and3-Amino-5-phenylpyrazole is studied. And their application in explosives detection is also investigated. The compounds exhibit excellent blue emissions. Among them, the compound with nitro group (4d) presents the emission quenching. This character implies that these compounds might be used as a fluorescent chemosensor in detecting the trace explosive.