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1、TetrahedronLettersTetrahedronLetters45(2004)7891–7894Cupricsulfatepentahydrate(CuSO4Æ5H2O):amildandefficientcatalystfortetrahydropyranylation/depyranylationofalcoholsandphenolsAbuT.Khan,*LokmanH.ChoudhuryandSubrataGhoshDepartmentofChemistry,IndianInstituteofTechnologyGuwahati,Guwahati781039,IndiaRec
2、eived22July2004;revised15August2004;accepted24August2004Availableonline11September2004ThispaperisdedicatedtoProfessorH.Ilaontheoccasionofher60thbirthdayAbstract—VariousalcoholsandphenolscanbesmoothlyconvertedtothecorrespondingTHPethersusing20mol%CuSO4Æ5H2Oundermildreactionconditionsatroomtemperatu
3、re.Someofthemajoradvantagesofthisprocedurearenonaqueouswork-up,verygoodyields,lessexpensivecatalystandcompatibilitywithotherprotectinggroups.Ó2004ElsevierLtd.Allrightsreserved.Thetetrahydropyranyl(THP)groupisfrequentlyuseduse.4,8,9,14Thereisaneedforagreenercatalyticallyfortheprotectionofalcoholsan
4、dphenolsduetotheirefficientmethod,whichmightworkundermildandeaseofpreparationandstabilityunderawidevarietyeconomicallycheaperconditions.Asapartofourofreactionconditionssuchaswithhydrides,alkylatingongoingresearchprogramtodevelopnewsyntheticreagents,Grignardreagentsandorganometallicmethodologiesinvol
5、vingvariousnewreagents,16,17wereagents.1Inaddition,theyalsoserveasstableprotect-perceivedthatcupricsulfatepentahydrate,whichisinggroupinpeptide,nucleosideandnucleotide,carbo-readilyavailable,mightbeausefulcatalystfortetra-hydrateandsteroidchemistry.Tetrahydropyranylationhydropyranylationbecauseofi
6、tsmildLewisacidity.ofalcoholscanbeaccomplishedbyusingp-TSA,2Inthispaperwedisclosethatcupricsulfatepentahy-BFÆOEt3andPPTS.4Someoftherecentlyuseddratecanbeusedasanefficientcatalystfortetrahydro-32reagentsthatcancatalyzebothtetrahydropyranylationpyranylation/depyranylationofalcoholsandphenolsasanddepyr
7、anylationareZrCl,5I,6LiBr,7acetonyltri-showninScheme1.42phenylphosphoniumbromide(ATPB),8TBATB,9aluminiumchloridehexahydrate,10In(OTf),11Whenamixtureof1-hexadecanol1aand3,4-dihydro-3dialkylimidazoliumtetrachloroal
