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shapless 环氧化

liu1990518dong
2011-08-28 0人阅读 举报 0 0 暂无简介

简介:本文档为《shapless 环氧化pdf》,可适用于高等教育领域

JAmChemSOC,,FurtherspectroscopicandconductivitystudiesareinprogresstoelucidatethemechanismofchargetransportinthesematerialsAcknowledgmentismadetothedonorsofthePetroleumResearchFund,administeredbytheAmericanChemicalSociety,andResearchCorpforpartialsupportofthisworkJDFthanksBFGoodrichCoforfinancialsupportthroughaBFGoodrichFellowshipatCWRUSupplementaryMaterialAvailable:Tableofstructurefactorsfor,butanedionedihydrazone(pages)OrderinginformationisgivenonanycurrentmastheadpageCatalyticAsymmetricEpoxidationandKineticResolution:ModifiedProceduresIncludinginSituDerivatizationYunGao,RobertMHanson,JaniceMKlunder,SoYKO,HirokoMasamune,andKBarrySharpless*ContributionfromtheDepartmentofChemistry,MassachusettsInstituteofTechnology,Cambridge,MassachusettsReceivedJulyI,Abstract:TheuseofAorAmolecularsieves(zeolites)substantiallyincreasesthescopeofthetitanium(V)catalyzedasymmetricepoxidationofprimaryallylicalcoholsWhereaswithoutmolecularsievesepoxidationsemployingonlytomolTi(OiPr)generallyleadtolowconversionorlowenantioselectivity,inthepresenceofmolecularsievessuchreactionsgenerallyleadtohighconversion(>)andhighenantioselectivity(ee)TheepoxidationsofprimaryallylicalcoholsaredescribedEspeciallynoteworthyaretheepoxidationsofcinnamylalcohol,tetradecylpropen,allylalcohol,andcrotylalcoholcompoundswhichheretoforehadbeenconsidereddifficultsubstratesforasymmetricepoxidationInthecaseofallylalcohol,theuseofcumenehydroperoxidesubstantiallyincreasesboththereactionrateandtheconversion,evenintheabsenceofmolecularsievesIngeneral,enantioselectivitiesareslightlydepressed(byee)relativetoreactionsemployingmolTi(OiPr)Theepoxidationoflowmolecularweightallylicalcoholsisespeciallyfacilitatedand,inconjunctionwithinsituderivatization,providesforthesynthesisofmanyepoxyalcoholsynthonswhichwerepreviouslydifficulttoobtainThekineticresolutionoffoursecondaryallylicalcoholswithmolTi(OiPr)isalsodescribedTheroleofmolecularsievesinthereactionandtheeffectsofvariationinreactionstoichiometry,oxidant,andtartratearediscussedThereactionofanallylicalcoholwithtertbutylhydroperoxide(TBHP)inthepresenceofTi(OiPr)anddiethyltartrate(DET)toformanepoxyalcoholofhighenantiomericpuritywasintroducedin(SchemeI)'Sincethen,muchhasbeenlearnedaboutthisasymmetricepoxidationprocessSeveralreviewshavebeenpublished,*andtwothesesfromtheselaboratorieshavedealtwithmechanisticaspectsofthereacti~n~~Theepoxidationasinitiallydescribedemploysastoichiometricamountofcatalyst,eventhough,asnotedinoneofthefootnotestotheoriginalreport,reactionsofcertainsubstratescanbecarriedoutwithaslittleascatalystwithlittlelossofenantioselectivityandsomeincreaseinyieldIn,wereportedthat,withslightmodifications,thesameprocedurealsoeffectsthekineticresolutionofsecondaryallylicalcohols(SchemeII)Again,itwasnotedthatforcertainsubstratesjustequivofcatalystcanbeeffectiveOverthenextyears,nomajormodificationstotheprocedurewereintroducedTheasymmetricepoxidationreactionhasproventohavewideapplicability,evenwithuseofastoichiometricamountofcatalyst,andhasbeenthesubjectofanOrganicSynthesespreparationWerecentlyreportedasimplemodificationoftheoriginalprocedurewhichallowstheasymmetricepoxidationtobecarriedoutwithjustcatalyst'Thekeyfeatureofthecatalyticmodificationistheuseofmolecularsieves(zeolites)WenowreportinfullourstudiesrelatingtothisnewprocedureThemodificationspresentedheresignificantlyexpandthescope,effectiveness,convenience,andeconomyofthereactionInthefirstpartofthisreport,wepresentresultsrelatingtothesynthesisofepoxyalcoholsandtheirinsituderivatization,aswellaskineticresolutionsinvolvingcatalyticamountsofthetitaniumtartrate'DedicatedtoProfessorGeorgeBuchiontheoccasionofhisthbirthday$SchemeITi(OiPr),()DETtBuOOHCH,CI,°COR'()DETR'EtSchemeITi(OiPr),()DIPT"v"'OHtBuOOHOHcomplexInthesecondpartwediscussfactorswhichinfluencethereaction()Katsuki,TSharpless,KBJAmChemSOC,,()Finn,MGSharpless,KBInAsymmetricSynthesisMorrison,JD,EdAcademicPress:NewYork,Vol,Chapter,Rossiter,BEInAsymmetricSynfhesisMorrison,JD,EdAcademicPress:NewYork,Vol,Chapter,Pfenninger,ASynthesis,Thelastofthesereviews(Pfenninger)issomewhatoutofdateevenforthestoichiometricreaction,especiallywithrespecttothebestexperimentalproceduresandcatalyststructuretheAsymmetricSynthesisreviewsaremorecurrentAmericanChemicalSocietyJAmChemSOC,Vol,No,GaoetalTableICatalyticAsvmmetricEuoxidations“compdcatalysttemp,time,yield,eeentrvuroductnosieves’TitarttartrateOChTransDisubstituted,OHR=CJHAR=C,HAR=CHl,AR=phenylAR=pnitrophenylAR=pbromophenylACisDisubstitutedR=CHlAR=CgHlAR=PhCH,OCH,AUnsymDisubstitutedR=C,HA=CHATrisubstituted,,O”AAA*OH,,AO”lAQoHLowMolecularWeightOHAOHA()DET()DET()DET()DIPT()DIPT()DIPT()DET()DIPT()DET()DET()DET()DIPT()DET()DET()DET()DIPT()DIPT()CdY>Wh>h>h>’Y>h“AllreactionswerecarriedoutwithTBHPexceptforentry,whichemployedcumenehydroperoxide(CHP)Yieldsreportedareisolatedyieldsexceptentry,whichisforthecrudeproductbAmolecularsievesarelesseffectiveinthisreactiononlyCTheyieldwasnotdeterminedsince,afterh,thereactionwasfarfromcompleteHowever,seerefdThisreactionwasrunsolelyforthedeterminationofenantiomericexcessThus,thereactionwasnotworkedupandnoyieldwasobtainedeAsamixturecontainingglycidol,cumene,andsmallamountsofcumylalcoholafterdistillationGCandinsitutrappingbothindicatehighconversiontoglycidol(>)KO,SYSharpless,KBJOrgChem,,UseofTBHPleadstoincompletereactionAllee’sarereportedforthecrudematerial,unlessotherwisenotedEnantioselectivitywasdeterminedby‘HNMRanalysisofthederivedMTPAester,exceptforentries,,,and,whichweredeterminedby’HNMRshiftanalysisofthederivedacetateswithEu(hfc),inbenzened,entry,whichwasdeterminedbyHPLConachiralstationaryphase,andentry,whichwasdeterminedbyopeningbythiophenolCaron,MSharpless,KBJOrgChem,,andseeExperimentalSectionfollowedbyIHNMRshiftstudyofthederiveddiacetatef>indicatesthattheotherenantiomerwasnotdetectablebyNMR‘eereportedforrecrystallizedmaterial‘AmoreaccurateanalysisofeewasnotpossiblefromtheIHNMRspectrumbecauseofpoorlyresolvedpeaks’Foranimprovedprocedure,seerefResultsEpoxidationInvolvingEpoxyAlcoholIsolationOurresultsforcatalyticasymmetricepoxidationscarriedoutinthepresenceofmolecularsievesaresummarizedinTableIIngeneral,selectivityissomewhatlowerthaninthestoichiometriccase,moreoftheminorenantiomerbeingobtainedFortunately,,epoxyalcohols,whencrystalline,generallyundergodramaticeeimprovementuponrecrystallizationafelicitouscircumstance!Typicaltransdisubstitutedallylicalcohols(entries)canbeepoxidizedattoOCinatleastenantiomericexcess()Finn,MGPhDDissertation,MassachusettsInstituteofTechnology,()Woodard,SSPhDDissertation,StanfordUniversity,Stanford,CA,Cambridge,MA,()Martin,VSWoodard,SSKatsuki,TYamada,YIkeda,M()Hill,JGSharpless,KBExon,CMRegenye,ROrgSynfh()Hanson,RMSharpless,KBJOrgChem,,Sharpless,KBJAmChemSor,,,,(ee)withjustTi(OiPr)andtartrateThereactionsarequiterapid,generallycompleteinhAsinthestoichiometricprocedure,cisdisubstitutedallylicalcohols(entries)requirelongerreactiontimes(days)Itwasfoundthatsuchslowlyreactingsubstratesrequiremorecatalyst(IO)*andusuallyslightlyhigherreactiontemperaturesthaninthecaseofthetransallylicalcohols,inordertoachievecompletereactionwithminimallossofselectivityThemonobenzyletherof(Z)buten,diol(entry)wasnotsuccessfullyepoxidizedusingtheproceduredescribedhere,sinceafterh,thereactionwasstillfarfromcompleteOtherworkers,however,haveaccomplishedthisepoxidation~atalytically~()Inthisreport,wewillusethefollowingnomenclaturetodescribethecatalystsystemusedinthereaction:xycatalystreferstoxmolTi(iPr)dandymol’tartrateesterThisdiffersfromourearlier,lessspecificmethodofdescription,inwhich“stoichiometric”impliedTi(OiPr)andtartrateester,whichweassumedtobeactivecatalyst“Stoichiometric”isusedhereinreferencetoreactionswithatleastmolTi(OiPr)CatalyticAsymmetricEpoxidationandKineticResolutionJAmChemSoc,Vol,No,TableInSituDerivatizationofEpoxyAlcoholsoentryproductnomp,OCDee,bcompdyield,ORR=PNB'()R=TBDPSoilR=Tsd()'ORR=PNB(>)'R=TsR=NpsR=PNBR=TsR=TBDMS,,ORR=PNBR=TsR=Npsoiloiloiloilgdtdtdtdtldtd()(>()(>f"YieldsreportedareisolatedyieldsForthosecompoundswhicharenotoils,themeltingpointsandrotationsarereportedfortherecrystallizedmaterialPNB=pnitrobenzoyl,Ts=ptoluenesulfonyl,TBDPS=tertbutyldiphenylsilyl,Nps=naphthalenesulfonyl,TBDMS=tertbutyldimethylsilylEnantiomericexcessesinparenthesesareafterrecrystallizationa*ODd()DIPTwasusedinthisreactionConfigurationisoppositetothatdepictede>indicatesthattheotherenantiomerwasnotdetectablebyNMR(UnabletodetermineWhenthereactionsarecarriedoutattoOC,theratherslowlyreactingunsymdisubstitutedallylicalcohols(entriesand)areamongthebestsubstrates,bothinyieldandselectivityIncontrast,useofastoichiometricamountofcatalystleadstosubstantialepoxideopeningbothduringthereactionloandespeciallywhenthereactionisquenchedbytheadditionofwaterllEpoxideopeningwasnotobservedforunsymdisubstitutedallylicalcoholswithuseofthecatalyticprocedure,eveninthecaseoftetradecylpropenol(entryl),wheresolubilityconsiderationsmandateuseofmolTi(OiPr),(discussedunderConcentrationintheDiscussionsection)Trisubstitutedallylicalcohols(entries)tendtoreactveryrapidlyunderthesecatalyticconditionsInmanycases,aslittleasequivofTBHPcanbeusedHowever,comparedtothestoichiometricreactions,somewhatdiminishedselectivities(Le,,ee)appeartobetherulehereForexample,aphenylcinnamylalcohol(entry)affordsaproductofee,'*whereasunderstoichiometricconditionsithasalwaysbeenoneofourbestsubstrates(ee>)Whenveryspecificoptimizedconditionsareused(Amolecularsieves,DIPT,cumenehydroperoxide,andreactionat"C),highconversionofallylalcoholtoglycidol(entry)canbeachievedwithjustTi(OiPr)ThisfindingisespeciallysignificantinthatuseofastoichiometricamountofTi(OiPr)generallyleadstodecompositionofglycidol'SuchdecompositionnotonlyresultsinmuchlowerchemicalyieldsbutalsodecreasestheenantiomericpurityoftheproductILowmolecularweightallylicalcohols(entriesand)ingeneralposespecialproblemswithrespecttoproductisolationandorstabilityTheusualaqueousworkupleadstosubstantiallossofthewatersolublepr~duct'~'~~'~Alternativeisolationprocedures,includingtreatmentwithdimethylsulfideandsodiumfluoride,triphenylphosphine,"sodiumborohydride,Iandanhydroushydroxycarboxylicacids,"Jhavebeenemployedinthepast,anduseofacatalyticamountofTi(OiPr),shouldsimplifyallofthesemethodsTheisolationproceduresforthetwolowmolecularweightepoxyalcoholsdescribedhere(entriesand)employanhydrouscitricacidtoremovetitaniumInthecaseofglycidol(entry),thisquenchwasfollowedbydistillationIntheepoxidationofcrotylalcohol(entry),itwasfoundthattheproductafterdirectdistillationwasstillsubstantiallycontaminatedwithTBHPHence,theexcesshydroperoxidewasreducedwithtributylphosphinepriortodistillationThisisstillnotanidealworkup,sincethedistillationiscomplicatedbythehighlyviscousnatureofthepotresidueInaddition,polymerizationofanyepoxyalcoholcanoccurduringdistillation,especiallyiftheworkuphasinvolvedacidtreatmentInsomecases,suchpolymerizationscanbequiteexothermic,especiallyonalargescale*O()DBurdickandJWScottatHoffmannLaRocheInchaveinformedusthattheasymmetricepoxidationofthemonobenzyletherof(Z)buten,diolproceedswellunderdifferentconditionsWithuseofcacatalyst,epoxidationatOCfordaysgivesahighyieldofproductofeeDetailsofthisworkwillbereportedinduecoursebytheHoffmannLaRochegroup(IO)Lu,LDLJohnson,RAFinn,MGSharpless,KBJOrgChem,,()UseofananhydrouscitricacidworkupdramaticallyincreasestheyieldofinthestoichiometricTi(OiPr)reaction,butitdoesnotalleviatetheproblemofepoxideopeningpriortoworkupHollinshead,DMSharpless,KB,unpublishedresults()Productofeewasobtainedwith()dicyclododecyltartrateandTBHPinisooctane(catalyst)()Thedecompositionofepoxyalcoholsbythechiralcatalystismoderatelyenantioselective,themajorenantiomerdecomposingfasterthantheminorKO,SYSharpless,KB,unpublishedresults()Dung,JSArmstrong,RWAnderson,PWilliams,RMJOwChem)Harris,RN:Sundararaman,PDjerassi,CJAmChemSOC()Rossiter,BEKatsuki,TSharpless,KBJAmChemSOC,()Meister,CScharf,HDLiebigsAnnChem,()(a)Bessodes,MAbushanab,EAntonakis,KTetrahedronLett,,(b)Masamune,HSharpless,KB,unpublishedresults()Tuddenham,DSharpless,KB,unpublishedresults,JAmChemSOC,Vol,No,Gaoetal~TableKineticResolutionwithVariousTartrateconversion,ee,dconversion,ee,yield,tartratettartratetyield,()DIPT()DIPT()DCHT()DCHT~()DCDT>()DCDT>yield,conversion,ee,yield,conversion,ee,'ctartratetartrate,()DIPT>()DIPT()DCHT>()DCHT>>()DCDT>()DCDTc()DCHT'~'Allreactionswerecarriedoutat"CwithTi(OiPr),()tartrateester,andequivofTBHPisooctaneinthepresenceofAmolecularsieves,exceptasnotedAllrecoveredallylicalcoholshadthedepicted(R)stereochemistryYieldsareisolatedyieldsbasedonpercentconversion>eeindicatesthattheotherenantiomerwasnotdetectablebyNMR'EmployedequivofTBHP'TracecontaminationbyDCDTyieldcalculatedfrom'HNMRdataTheselowmolecularweightepoxyalcoholsarehighlydesirableaschiralbuildingblocksinawidevarietyofasymmetric~yntheses'~J~*~'However,thespecialproblemsassociatedwithsuchcompounds,namelywatersolubilityandincertaincasesapropensityfordecomposition,havediscouragedtheirwidespreadsyntheticuseItwastheseproblemsthatledustoconsideranalternativetotheirdirectisolation:insituderivatizationEpoxidationInvolvinginSituDerivatizationOneofthegreatestadvantagesof'carryingouttheasymmetricepoxidationwithonlyacatalyticamountofTi(OiPr)andtartrateesteristhepotentialforinsitutransformationsofthecrudeepoxyalcoholproductWehadusedsuchproceduresinstoichiometricreactions,fortheanalyticaldeterminationofenantiomericexcess,bydirectlyquenchinganaliquotofthereactionmixtureintoasolutioncontainingEt,N,(dimethyamino)pyridine(DMAP),andamethoxya(trifluoromethy)phenylacetylchloride(MTPAC,Mosherchloride)However,theamountofisopropylalcoholandchelatedtartratediesterpresentinthestoichiometriccaserendersinsituesterificationimpracticalforthepreparativeisolationofproductUndercatalyticconditions,ontheotherhand,thesecomplicationsarealleviated,andpreparativeinsituderivatizationbecomesfeasibleOurresultsaresummarizedinTableThepreparationofderivativesoftheselowmolecularweight,watersolubleepoxy

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