Table Of Content

ORGANOALUMINUMINTERMEDIATESINTHE SYNTHESISOFALLYL-ANDVINYL-SILANES By MANLUNGKWAN ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT OFTHEREQUIREMENTSFORTHEDEGREEOF DOCTOROFPHILOSOPHY UNIVERSITYOFFLORIDA 1999 TothemightyGodofthisuniverse, myparents,mysisterandmyfriends,who supportandencourageme ACKNOWLEDGMENTS Iwouldliketoexpressmyappreciationtomyresearchdirectorandmentor, Dr.MerleA.Battiste,forhispatientguidanceandgenerosity.Heisdefinitelythe toughestbutthekindestprofessorthatIhaveevermet.Hissuperiorknowledgeand highstandardalwaysinspireme.Ithankhimforthephilosophicaldiscussionsandthe attitudeadjustment.Underhisguidance,Ihavelearnedtobeamechanisticchemist andaleaderinmygroupaswellasintheorganicteachingassistantteam. SpecialthanksgotoDr.W.R.Dolbier,Jr.,fortheadvicethathegaveme.I alsothankDr.DavidRichardson,Dr.TomasHudlicky,Dr.DennisWright,andDr. KermethSloanfortheirparticipation.AcknowledgmentalsogoestoDr.McElwee- Whiteforherearlyguidance.ShemademerealizehowimmatureIwas. 1deeplyappreciatemyfather,MingKwan,mymother,KoonLingChoi,and mysister,Diana,fortheirunlimitedsupportandencouragement.Iwantthemtoknow IlovethemaswellasmynieceYasmineandnephewShayansomuch.We,Chinese, seldomtalkaboutloveamongfamilymembers.Iknowfromtheiractionsthatthey lovemealot.Iamverygratefultomyverybestfriends,JimandJeanFoerster.I haveknownthemforfiveyearsandsharedalotofvaluablememories.Iamcurrently livingwiththemasafreeloader.Needlesstosay,theyareverygenerousandkind.I alsowanttoexpressmydeepappreciationtomyspiritualparentsBobandTerri Blakeslee.TheyputmeundertheirwingandhelpmegrowasaChristian.Without 111 theBlakeleesandFoersters,Iwouldnothavemadeitthisfarinmycareer.Many thankstoJoeRanney,Dr.YuCheukCheng,JohnPerlette,membersoftheWright (especiallyClaudeRobotham),Enholm,andHudlickygroups,andthemembersof theVineyardChristian Fellowshipfortheirfriendshipandsupport. SpecialthanksgotomyformersupervisorDr.NorrisHoffmanforhisearly guidanceandsupportwhenIwasanundergraduate.Heislikemyfather.1alsowant toexpressmyappreciationtomymiddleschoolteachersMs.ChiWahWongandMs. ShuTaiLee.Theychangedmywholelife.TheychangedthewaythatIlookedat things.Theyshowedmehowtobeagoodperson.1stillrememberwhen1wasatMs. Lee’sfuneral,IthoughtthatifIbecomeateacher,1wouldliketobejustlikeherand Ms.Wong.Theseteacherslookedaftertheirstudentsjustliketheirownchildren. IwanttopraiseGodwhathehasdoneinmylife.Heallowsthingstohappen tomesothatIcangrowunderhisplan.Heisalwaysbymysidetoprotectme.Here, Iwouldtosay,"ThankyouJesus;praisetheLord."Attheend,1wouldliketopray thatGodblessallthesepeoplewhoaresogenerousandkindtome. "Dear friends, let us love one another, because love comes from God. WhoeverlovesisachildofGodandknowsGod.Whoeverdoesnotlovedoesnot knowGod,forGodislove.AndGodshowedhisloveforusbysendinghisonlySon intotheworld,sothatwemighthavelifethroughhim.Thisiswhatloveis:itisnot thatwehavelovedGod,butthathelovedusandsenthisSontobethemeansby whichoursinsareforgiven."1John4:7-10. IV 5 TABLEOFCONTENTS page ACKNOWLEDGMENTS iii ABSTRACT vi CHAPTERS 1 INTRODUCTION 1 HistoricalBackgroundandPropertiesofAluminum 1 HistoricalBackgroundandPropertiesofSilicon 1 PetersonOlefinationReaction 20 2 TRANSFORMATIONOFKETONESTOVINYLSILANES 25 ApplicationofOrganoaluminumsinVinylsilanesSynthesis 34 NewDevelopmentintheApplicationsofOrganoaluminumsinVinylsilane Synthesis 53 3 TRANSFORMATIONOFKETONESTOALLYLSILANES 58 Introduction 5g OrganoaluminumsPromoted"AbnormalPetersonOlefination"inthe AllylsilaneSynthesis 71 ApplicationofCeriumtrichlorideinOrganoaluminumsPromoted "AbnormalPetersonOlefination"intheSynthesisofAllylsilanes 79 4 EXPERIMENTAL 101 APPENDIX 129 SPECTRALDATA 129 REFERENCES I37 BIOGRAPHICALSKETCH I43 V AbstractofDissertationPresentedtotheGraduateSchool oftheUniversityofFloridainPartialFulfillmentofthe RequirementsfortheDegreeofDoctorofPhilosophy ORGANOALUMINUMINTERMEDIATESIN ALLY-ANDVINYL-SILANESSYNTHESIS By ManLungKwan August1999 Chairman:MerleA.Battiste MajorDepartment:Chemistry Manymethodologieshavebeendevelopedforthepreparationofallyl-and vinyl-silanes,butmostoftheexistingmethodsinvolvedatleasttwoormoresynthetic steps.Wehavedevelopedaconvenientone-potreactiontoproduceeitherallyl-or vinyl-silane. Tris(trimethylsilylmethyl)aluminumlithiumbromidecomplex2-1,aselective Petersonolefinationreagent,reactedwithbenzophenoneatelevatedtemperaturesto afford (2,2-diphenylvinyl)trimethylsilane,2-4, reactions of2-1 with otherketones affordedunsatisfactoryresults.Therefore,themethodologywasextendedtoemploy 1.2eq.ofLiCH2TMS(fornon-enolizableketones)or1.5eq.ofLiCH2TMS/CeCl3 (forenolizableketone)tofulfilltheinitialalkylationsteptothecarbonylgroupwith xyleneassolvent.Reactionmixtureswereallowedtoreflux(24to96hours)after VI 1 subsequent additionof1.4eq.ofdiethylchloroalanefollowedbyintroductionof0. eq.of1 MH2OinTHF(togenerateacatalyticamountofalumoxanes)toproduce eithervmylsilanesorallylsilanes.Ingeneral,reactionsofnon-enoliazablearomatic ketonesaffordedthecorrespondingvinylsilanesasmajorproductsinfairtogood yieldswithhighchemo-andstereoselectivity,while,reactionsofenolizableketones affordedthecorrespondingallylsilanesasmajorproductsinrespectableyieldswith highregioselectivity. ThereactionmechanismisbelievedtoproceedthroughanintramolecularEl- hkepathwayproducingcarbocationsasthereactiveintermediate.Thisconclusionis supportedbythe formationofanaddition(ethylation)product inthe reaction of xanthoneandformationof 5-phenyl-10,ll-dihydro-5//-dibenzo[a,^/lcycloheptene.In bothcases,thecarbonscontaininghydroxygrouparetertiarycenters. Inorderto substitutetheoxygen,cationsmusthaveformedpriortotheethylationorreduction. Theformationofthe ethylationandthereductionproductstronglysuggestedthat theseeliminationreactionsproducingvinylsilanesorallylsilanesproceedthrougha E-1likepathwayratherthanE2-likeorsyn-cyclicmechanisms.Insummary,auseful one-potprocedurefortheformationofallyl-vinyl-silanesfromketoneshasbeen developed. Vll CHAPTER 1 INTRODUCTION Allyl-andvinylsilanesaresilicon-containingolefins.Siliconaltersthereactivity ofthe double bond ofallyl- and vinylsilanes; therefore, they are valuable synthetic intermediates.Thereisagreatdealofmethodologyforthepreparationofthesetypesof compounds,butveryfewoftheavailablemethodsinvolveone-potsynthesisandare mediated by organoalumimuns. The goal of this dissertation is to report a new convenient,one-potsynthesisinvolvingorganoaluminumpromotedEl-likeelimination toproduceallyl-andvinylsilanes. HistoricalBackgroundandPropertiesofAluminum Intheearth’scrust,thethirdmostabimdantelementisaluminum.Itisaductile, malleableandbluish-whitemetal,whichwasfirstdiscoveredbyAntoineLavoisierin 1787,namedbySirHumphryDavyin1807,andisolatedinpureformbyHansChristian Orstedin1825.AluminumbelongstoGroupIIIAontheperiodictable;therefore,the principaloxidationstateofaluminumis+3(Table1-1).Amongitselevenisotopeswith atomicweightsbetween22and31,aluminum-27is 100%naturallyabundant. The remainingisotopesareartificialandradioactive. 1 2 Table1-1.Propertiesofaluminum. Element Aluminum ElectronConfiguration Ne3s^3p' Atomicnumber 13 Atomicweight 26.9815 Meltingpoint 660.37°C Boilingpoint 2467°C Oxidationstate +3 SpecificGravity 2.699@20°C IonizationEnergies 5.98,18.82,28.44,153.77eV Productionofaluminumanditsderivatives PurealuminumcanbeobtainedviatheHallProcesswhichinvolveselectrolysis ofaluminumoxide,AI2O3,fromnaturalbauxite.IntheHallprocess,aliquidmixtureof aluminum oxide, cryolyte, and fluorite (cryolyte and fluorite are usedto lowerthe meltingpointofaluminumoxide)iselectrolyzedtoaffordaluminummetalandoxygen gas(equation1-1). 2AI2O3->4A1+3O2 equation1-1 Purealuminumisabluish-white,highlymalleable,andductilemetal.Aluminum metalisprotectedbyitsoutsideoxidecoatingand,therefore,resistsoxidation.However, withoutitsprotectiveoxidelayer,thelowionizationenergyofaluminummakesitreadily 3 oxidizedbyvariousofchemicalstoa+3oxidationstate. Thus,organoaluminumscanbe madebyreactionsofpurealuminumwithalkylhalidesthroughredoxreactions. Organoaluminumcompoundsarepyrophoric. Standardtechniquesforhandling air-sensitive materials are necessary when one prepares or handles organoaluminum substances. Organoaluminum compounds are usually of the following types: triakylaluminum(R3AI),dialkylaluminumhalides(R2AIX),andalkylaluminumdihalides (RAIX2),whereRcanbeanalkyl,alkenyl,aryl,oralkynylgroups. Alkylaluminumhalides Alkylaluminum halides can be prepared from the reactions of sesquihalide (R3AI2X3)withsodiumhalides(NaX)toaffordthecorrespondingR2AIXspeciesorwith stoichiometricamountsofaluminumhalides(AIX3)toproducethecorrespondingRAIX2 derviatives(Scheme1-1).3 2A1+3RX R3AI2X3: R2AIX+RAIX2 +Na(RAlX3) Scheme1-1 Dialkylaluminumhydrides Zieglerandco-workersdevelopedadirectsynthesisofdialkylaluminumhydrides (R2AIH) involvingthereactionofatrialkylalane, activated aluminum, andhydrogen under pressure at elevated temperature (equation 1-2). An alternative method is to extrudeanolefinby(^-hydridetransferfromtrialkylalaneatelevatedtemperatures,as showninequation1-3.