Study Synthesis Of Pvrano Derivatives Via Multicomponent Condensation Reactions By Ionic Liquid

In recent years,Multi-component reactions(MCRs)have received a great deal of attention,most notably for the construction heterocyclic libraries.MCRs strategies offer significant advantages of their excellent synthesis efficiency,simple procedure,structural diversity,environmentally friendly,atom economy and closer to the ideal synthesis.Meanwhile,in recent times,the use of room temperature ionic liquids as reaction medium and catalyst in organic synthetic processes has gained considerable importance due to their solvating ability,negligible vapor pressure,easy recyclability and reusability.In this paper,a varity of pyrano derivatives which poss very important biological and pharmaceutical activities were synthesized using ionic liquids as catalyst through MCRs.The main contents as follows:The definition,development,types,properties and synthesis of ionic liquids and the multicomponent reaction were introduced.And the applications of ionic liquids in multicomponent organic synthesis reaction were simply reviewed in recent years.A serious of 1,4-dihydropyrano[2,3-c]pyrazole derivatives were synthesized by a four-component one pot condensation of aromatic aldehydes,malononitrile,hydrazine or hydrazinobenzene and ethyl benzoylacetate using basic ionic liquid 1-butyl-3-methyl imidazolium hydroxide([Bmim]OH)as catalyst.Effect of the catalyst,reaction temperature,catalyst amount,solvent on the yield was investigated.The optimum reaction conditions were determined and the possible mechanism was proposed.Moreover,the catalyst could be recovered conveniently and reused for at least four times without evident loss of activity.The products were identified by 1H NMR,IR,MS techniques and elemental analysis.The present methodology offers several advantages such as milder conditions,shorter reaction time,excellent yields and environmental friendliness.A series of 1H-pyrano[2,3-d]pyrimidin-2(8aH)-one derivatives were synthesized via one-pot,three component reaction of aromatic aldehydes,urea or thiourea,and 3,4-dihydro-2H-pyran using a green and inexpensive Bronsted acidic ionic liquid 1-methyl-2-pyrrolidinone hydro sulfate([Hnmp]HS04)as catalyst under solvent-free conditions.Effect of the reaction temperature,solvent on the yield was investigated.The optimum reaction conditions were determined and the possible mechanism was proposed.The method has several advantages such as mild conditions,shorter reaction time,high yields and environmentally benign procedure.Moreover,the catalyst could be recovered conveniently and reused for at least four times without evident loss of activity.The products were identified by 1H NMR,IR and elemental analysis.A series of 14-aryl-14H-dibenzo[a,i]xanthene-8,13-diones were synthesis via three-component reaction of aromatic aldehyde,?-naphthol and 2-hydrox-y-1,4-naphthoquinoneor in acidic ionic liquid of[Hnmp]HSO4.Effect of the catalyst,reaction temperature,catalyst amount,solvent on the yield was investigated.The optimum reaction conditions were determined and the possible mechanism was proposed,which provides an efficient,fast and environmentally friendly new procedure for the preparation of 14-aryl-14-dibenzo-[a,i]xanthene-8,13-diones.The products were identified by 1H NMR,IR and elemental analysis.The conclusions of the thesis and the prospect of the applications of ionic liquids in multicomponent reaction were described.