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1、5Synthesisstrategy ProtectionGroups2021/6/282021/6/281Content2021/6/282021/6/28IntroductionandConcept2.4.12.4.23ProtectingGroupsforAlcohol32.4.3ProtectingGroupsforCarbonylsProtectingGroupsforAmines2.4.52.4.4SummaryandHomework2.4.6ProtectingGroupsforDiols21.IntroductionandConceptsProtecti
2、ngGroupProtectionanddeprotectionProtection---transformstheinterferingFGintoadifferentoneDeprotection---transformthenewFGbackintotheoriginalgroupatalaterstageofthesynthesisOnepracticalsolutionistotemporarilyblockareactivepositionbytransformingittoanewFGthatwillnotinterferewiththedesiredTra
3、nsformation.ThisnewblockinggroupisProtectingGroup.Nucleophilicspecies–GrignardreagentKetone--aldehydeacids,basesandnucleophilesAlcohol-amineSynthetictargetsmanyproblemsmorethanoneFGcompetitivereaction32021/6/28OtherusesofthePGThePGcanbeusedtoprovidedirectingeffects,influencesolubility,and
4、otherphysicalproperties,makeiteasiertoisolateorcrystallize.Asapro-druginpharmaceuticalindustry,Solid-phaseattachment,taggingmolecules(fluorescencetagging)Theuseoftheprotectinggroup—whenandhow1)Avoidedstep,butitcannotbeavoided,2)PlanningtheorderofasynthesisforinsertionofagivenFGcanminimize
5、theuseofPG.3)ThePGmustberelativelyinertandeasytounmaskinhighyield.1.IntroductionandConceptsIntroduce,removeBlockunblockProtectdeprotectMaskUnmask4AnperfectprotectinggroupmustBeeasilyobtained,stableandno-toxicityNotintroducethestereo-centertothemolecularIntroduceandremoveinhighyieldBeeasil
6、yisolatedfromthesystemafterthecleavage2021/6/28Summary:Protectingwhenalcohols,aldehydes,ketones,amines,doubleortriplexbondsandotheractivegroupsarewithcompetitivereactions.1.IntroductionandConcepts5Ether,relativelyinert,butuneasilyremovedacyclicacetalsorketalsesters,muchinertbuteasilyremov
7、ed2021/6/28SothekeyproblemsforProtectionGroupsisReactionconditionsforintroducecircumstanceconditionsforstableReactionconditionsforremoved2.ProtectionGroupsforAlcohols6ReactionconditionsMethylethersaremostinertPGandstabletostrongbases,nucleophiles,organometallics,yli
