AdvancedOrganicChemistryLecture11RearrangementsReactionsMolecularRearrangements:Itrefersthosereactionsinwhichthecarbonskeletonorthepositionoffunctionalgroupchanged.分子中的基團或原子從一個原子遷移到另一個原子上，碳胳或官能團的位置發生變化的一類反應稱為分子重排反應。Rearrangementwasclassifiedbytheelectronpropertyofthemovinggroup,suchasNucleophilicrearrangement,Electrophilicrearrangement,Radicalrearrangement,etc.MECHANISMSNucleophilicRearrangementsWhitmore1,2-shiftOpensextetStepI.Creationofasystemwithopensextet:FormationofaCarbocation

Wagner-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:Nov