classic terpene syntheses

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1、BaranLabClassicTerpeneSynthesesTomMaimoneI.AnIntroductiontoTerpenes-Terpenesareanenormousclassofnaturalproductsspanningwellover30,000members-Theyhavebeenusedthroughouthistoryforabroadvarietyofpurposesincludingperfume,medicine,andflavoring-Recognizedearlyonasbeingcomposedofisoprenefra

2、gmentsIsoprene-Isopentyldiphosphate(IPP)anddimethylallyldiphosphate(DMAPP)laterfoundtobetheactualbuildingblocks-Thereare2biosyntheticpathwaysfortheproductionofIPPandDMAPP,themevalonatepathwayandthemorerecentlydiscovereddeoxyxylulosepathwayTheChemistryoftheMevalonatePathway:OOOAldolan

3、dOHOOHOHOHSCoAClaisenHydrolysisHO2CNADPHHO2CHOCSCoASCoASCoA2OSCoAacetoacetyl-CoAHHMG-CoAmevaldicacidmevaldicacidSEnzhemithioacetalOacetyl-CoAONADPHOHOPOADP-CO2OOHOHOH2xATP-EquilibriumHO2COPPOPPOHfavorsDMAPPIsomeraseOOPPDMAPPIPPmevalonicacid(MVA)NH2TheChemistryoftheDeoxyxylulosePathwa

4、y:OOHPOHNOHOHOOHOOPinacol-typeNADPH1.CTPOPrearrangementOPOPOPONOOPO2.ATPOOHOHOHOHOHOOHOHOHH+2-C-methyl-D-erythritol4-PHOOHOOH1-deoxy-D-xylulose5-POO(frompyruvicacid)POPOPPIsomeraseOPPOOHstepsnotDMAPPIPPfullydeterminedOHOH*Foranexcellentreviewonnaturalproductsandbiosynthesissee:Dewick

5、,P.M.MedicinalNaturalProducts:ABiosyntheticApproach.Wiley,2002.1BaranLabClassicTerpeneSynthesesTomMaimone-AllterpenesareformedthroughthereactionsofIPPandDMAPP:stereospecificprotonlossMonoterpenesOPPOPPOPPOPPDMAPPIPPHHgeranylPP(GPP)-repeatseveraltimes:SesquiterpenesHemiterpenes(C5)OPP

6、Monoterpenes(C10)farnesylPPSesquiterpenes(C15)Diterpenes(C20)DiterpenesSesterterpenes(C25)OPPTriterpenes(C30)geranylgeranylPPTetraterpenes(C40)Triterpenes(Steroids)squalene-TheinterestingChemistryinvolvesthefateoftheopen-chainterpenes.Aseeminglyendlessnumberof(enzyme-mediated)carboca

7、tioncyclizationsleadstomanydifferentcarbocyclicskeletons,whichareoftenfurtheroxidizedOPPandrearranged.OPPOPPwithonly2prenylunits:•7uniqueskeletons•severalsitesofhydrationoreliminationtoterminatecarbocationMenthanePinaneBornaneFenchaneIsocamphaneCaraneThujaneTakeHomeMessage:Complexity

8、increasesTyp