Study On The Synthesis Of Polyhydroquinoline,Naphthopyran And 3,4-dihydropyrimidin-2(1H)-ones Promoted By Ionic Liquids

This paper is mainly about the study of the application of ionic liquids in the following organic synthesis including the preparation of polyhydroquinolines,naphthopyran compounds and 3,4-dihydropyrimidi n-2(1H)-ones via Biginelli reaction.Firstly,a series of polyhydroquinolines were synthesized with aldehydes,cyclohexanedione,ethyl acetoacetate and ammonium acetate.The optimal conditions has been obtained:[bpy]BF4 used as the reaction medium,the molar ratio of aldehydes,cyclohexanedione,ethyl acetoacetate,ammonium acetate and Cu(?)triflate used as1:1:1:1.2:0.1,The reactions were carried out in 60 ? in 1.5 hours,which presented good yields of polyhydroquinolines.Secondly,a series of naphthopyran compounds were synthesized with aromatic aldehyde,a-naphthol and malononitrile catalyzed by[Dmnpmim]BF4.The reaction conditions had been optimized and a better route was obtained:ethanol used as the reaction solvent,the molar ratio of aromatic aldehyde,a-naphthol,malononitrile and[Dmnpmim]BF4 was 1:1.5:1.5:0.1.The reactions can be finished at 60? in 3 hours in good yields.Thirdly,3,4-dihydropyrimidin-2(1H)-ones were synthesized via Biginelli reaction using aromatic aldehyde,?-dicarbonyl compounds and carbamide as substrates.The better reaction conditions was obtained:Solvent-free conditions,1:1.5:1.5:0.25 ratio of aromatic aldehyde,B-dicarbonyl compounds,carbamide and FeCl3·6H2O,using 5mmol bpy]BF4 as catalyst.The reactions carried out in 60? in 0.5 h,which could obtain a higher yields of 3,4-dihydropyrimidin-2(1H)-ones.The above reactions were all carried out by using ionic liquids as catalysts or reaction medium and simple operation,significant rate enhancement,mild reaction conditions,environment benign and good yields have been observed,which conforms to green chemistry.