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1、REVIEWSynthesisofaromaticheterocyclesThomasL.GilchristChemistryDepartment,TheUniversityofLiverpool,Liverpool,UKL697ZD.E-mailtlg57@liv.ac.ukReceived(inCambridge,UK)7thJune1999Covering:March1997toFebruary1999correspondingbis(trimethylsilyl)furanforthesynthesisofother3Previousreview:J.Chem.Soc.
2、,PerkinTrans.1,1998,6153,4-disubstitutedfuranshasalsobeenreviewed.AnimprovedversionofMarshall’ssynthesisoffuransfromβ-alkynyl1Introductionallylicalcohols,makinguseofsilvernitrateonsilicagelasthe42Furansandbenzofuranscatalyst,hasbeendescribed.3ThiophenesandbenzothiophenesAsinearlierreviews,se
3、veraloftheusefulnewroutesto4Pyrrolesfuransinvolvecyclisationreactionsinwhichoxygennucleo-5Indoles,indolizinesandcarbazolesphilesundergoadditiontoalkynes.Theintramolecularadd-6Oxazoles,thiazolesandbenzothiazolesitionofenolateanionstoactivatedalkynesprovidesasimple7Isoxazoles,isothiazolesandfu
4、sedanaloguesandversatileroutetoseveralfurans.Anexampleisshown8ImidazolesandbenzimidazolesinScheme1;otherterminalactivatinggroupsonthealkyne,9Pyrazolesandindazolesincludingbenzenesulfonylandvinylgroups,arealsoeffectivein510Oxadiazolesandthiadiazolespromotingthecyclisation.Fulldetailsofthescope
5、andlimit-11Triazoles,benzotriazolesandtetrazolesationsofthesimilarbasecatalysedcyclisationof1-aryl-and1-612Pyrones,coumarinsandchromonesvinylpent-4-ynonestofuranshavealsoappeared.Twoother13PyridinesrelatedcyclisationsofalkynesareshowninScheme2.Methyl14Quinolinesandisoquinolinesfuran-2-acetat
6、esareformedbythepalladiumcatalysedcyclis-715Pyrimidinesandquinazolinesationandcarbonylationof5-hydroxyenynes1andarelated16Otherdiazines,triazinesandtetrazinescyclisation,usingpotassiumtetraiodopalladateasacatalyst,817Referenceshasbeenusedinanewsynthesisofrosefuran.Thebaseinducedcyclisationof
7、acetylenicketonessuchas2providesa1Introductionrouteto2-alkenylfurans;theauthorssuggestthatcumulenes9suchas3areintermediates.Thisreview,aswithpreviousonesintheseries,hastheaimofcoveringreportsofnewandimprovedmethodsofconstruc-tionofaromaticheterocyc