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1、COMMUNICATIONSDOI:10.1002/adsc.20060038333Iron-Catalysedsp–spCross-CouplingReactionsofUnactivatedAlkylHalideswithAlkylGrignardReagentsaaaa,KrishnaG.Dongol,HuishiKoh,ManisankarSau,andChristinaL.L.Chai*aInstituteofChemicalandEngineeringSciences,1PesekRoad,JurongIsland,Singapore6278
2、33Fax:(+65)-6316-6184;e-mail:Christina_chai@ices.a-star.edu.sgReceived:July27,2006;Revised:March9,200733Abstract:Iron-catalysedsp–spKumadacouplingformationofundesiredby-productssuchasthatre-withprimaryandsecondaryalkylhalides(RX)andsultingfromhomocoupling,disproportionationandalk
3、ylGrignardreagentshasbeenachievedinlowtobeta-eliminationreactions.Thusforareactionasout-goodyieldsdependingonthenatureoftheRlinedinScheme1,thedesiredcross-couplingreactiongroup.toformproductDsuffersfromcompetitionwiththeformationofdeceneA,decaneBandeicosaneC,theKeywords:alkylhali
4、des;cross-coupling;Grignardby-productsthatarisefromthelimitingreagent,thereactions;ironalkylhalide.By-productsarisingfromtheGrignardreagentsarealsolikelybutduetotheirvolatility,thesewerenotanalysed.Ourinitialstudiesfocusedontheuseofiron(II)acetateasthecatalystindiethylether.Alarg
5、eThedirectcarbon-carboncross-couplingreactionofnumberofligands(Figure1)werescreened–theseorganometalliccomponentswithalkylhalidesisoneincludedtheuseofphosphines,phosphites,amines,ofthekeychemicaltransformationsinsyntheticbutadiene.Ofthese,theuseofXantphos(1)gavechemistry.Thefield
6、isdominatedbytheuseofcata-moderatetogoodyieldsofthecross-couplingprod-lystssuchasnickel,palladiumandcopperwithalkyluct.Itisinterestingtonotethattheuseof2,aconfor-metalssuchasalkylGrignards(Kumadacoupling),mationallyflexiblediphosphinerelatedtoXantphosalkylborons(Suzuki–Miyauracou
7、pling)andalkylgavemuchloweryieldsofthecrosscouplingproduct[1]zincs(Negishicoupling).Recently,therehasbeen(5%versus51%yield).Similarlythediphosphine3intensiveinterestinthedevelopmentofironcatalystsalsogavepooryieldsofthedesiredcross-coupling[2]forCCbondformation.Thisisinpartdueto
8、theproduct,indicatingthatthenatureofthes
