高等有机化学-Lecture11

AdvancedOrganicChemistryLecture11RearrangementsReactionsMolecularRearrangements:Itrefersthosereactionsinwhichthecarbonskeletonorthepositionoffunctionalgroupchanged.分子中的基团或原子从一个原子迁移到另一个原子上，碳胳或官能团的位置发生变化的一类反应称为分子重排反应。Rearrangementwasclassifiedbytheelectronpropertyofthemovinggroup,suchasNucleophilicrearrangement,Electrophilicrearrangement,Radicalrearrangement,etc.MECHANISMSNucleophilicRearrangementsWhitmore1,2-shiftOpensextetStepI.Creationofasystemwithopensextet:FormationofaCarbocationWagner-Meerweinrearrangement2.FormationofaNitreneStepII.MigrationStepIII.Themigrationorigin(A)acquiresanoctetRearrangementwithsubstitution(combinationswithanucleophile)Rearrangementwithelimination(lossofH+)TheActualNatureoftheMigrationTheconfigerationofYisretainedInversionofB

BeckmannRearrangementRacimationisfoundatB:InversionoccursatB:SN1-likeSN2-likeWhenBisateriaryatomorhasonearylgroupandatleastoneotheralkylorarylgroupSN1-likeInothercase,SN2-like1.2.WhenRisarylorvinyl,theintermediateisprobablyformedWhenRisalkyl,theintermediateisnotformedInversionatAandBInversionatAonlyMigratoryAptitudesPinacolicRearrangementPhenylwithelectrondonorgroupmovefirstUnderHNO2,theaminoalcoholrearrangesasthatofpinacol

α-EthandioneRearrangementα-Ethandionewithα-hydrogenwillproceedcondensationIfNaOHwasreplacedbyNaOMeort-BuONa,α-hydroxycarboxyesterwillbeproducedUsually,ethyloxyanionactsasareductionreagent.BeckmannRearrangementThegroupoppositetohydroxywillshiftTheshiftwillkeepthestereostructureofchiralcenterBaeyer-VilligerRearrangementGroupmovedasthefollowingorder:tertiaryalkyl＞aryl＞H＞secondaryalkyl＞primaryalkyl＞methyl

ThecumenehydroperoxiderearrangementisquiteresembletheBaeyer-VilligerRearrangement

ImportantindustrialreactionformanufacturingphenolandacetoneMemoryeffectsLongerNucleophilicRearrangementFree-RadicalRearrangementsElectophilicRearrangements例FavorskiiRearrangementMechanismofFavorskiiRearrangementForasymmetriccycloprapanone,thestableanionformdominantlyDifferentα-chloroketoneformsamerearrangementproduct:IntramolecularSN2attack(structuremaintaining):StevensRearrangementStructuremaintainingThesulfoniumcationdoesthesame

SommeletRearrangementWittigRearrangementFriesRearrangementReaction1,2-rearrangementsA.CarbontocarbonmigrationsofR,H,andArWagner-MeerweinandrelatedReactions:t-BuClt-BuClThePinacolRearrangementsemi-pinacolrearrangementTiffeneau-Demjanov

Overmanrearrangement:NovelCatalystsfortheOvermanRearrangementIevaJaunzeme,aAigarsJirgensons*SYNLETT2005,No.19,pp2984–298601.12.205AuCl,AuCl3,andPtCl4人有了知识，就会具备各种分析能力，明辨是非的能