高等有机化学之重排反应ppt课件.ppt

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1、Chapter8MolecularRearrangementsIClassificationofRearrangementReactionsIINucleophilicRearrangement1Wagner-Meerweinrearrangement2PinacolicRearrangement3α-ethandioneRearrangement4BeckmannRearrangement5Baeyer-VilligerRearrangementIIIElectrophilicRearrangement1Fa

2、vorskiiRearrangement2StevensRearrangement3WittigRearrangement4FriesRearrangementIVRadicalRearrangementIClassificationofRearrangementReactionsMolecularRearrangements:itrefersthosereactionsinwhichthecarbonskeletonorthepositionoffunctionalgroupchanged.Usuallyth

3、erearrangementwasclassifiedbytheelectronpropertyofthemovinggroup,suchasNucleophilicrearrangement,Electrophilicrearrangement,Radicalrearrangement,etc.NucleophilicrearrangementElectrophilicrearrangementRadicalrearrangementIINucleophilicRearrangement1Wagner-Mee

4、rweinrearrangement(Carboncationrearrangement)StablecationStablecationDemyanovrearrangement2PinacolicRearrangement？ThestablecationformedsuperiorPhenylgroupmovefirstGroupmovedasthefollowingorder:aryl＞alkyl＞HUnderHNO2,theaminoalcoholrearrangesasthatofpinacolQue

5、stionAnswer3α-EthandioneRearrangementα-Ethandionewithα-hydrogenwillproceedcondensationIfNaOHwasreplacedbyNaOMeort-BuONa,α-hydroxycarboxyesterwillbeproducedUsually,ethyloxyanionactsasareductionreagent.4BeckmannRearrangementThegroupoppositetohydroxywillshiftTh

6、eshiftwillkeepthestereostructureofchiralcenter5Baeyer-VilligerRearrangementGroupmovedasthefollowingorder:tertiaryalkyl＞aryl＞H＞secondaryalkyl＞primaryalkyl＞methylThecumenehydroperoxiderearrangementisquiteresembletheBaeyer-VilligerRearrangementHydroperoxiderear

7、rangementImportantindustrialreactionformanufacturingphenolandacetoneIIIElectrophilicRearrangementElectrophilicrearrangementisnotsocommonasnucleophilicrearrangementThetransitionstateis:1FavorskiiRearrangementMechanismofFavorskiiRearrangementForasymmetriccyclo

8、prapanone,thestableanionformdominantlyDifferentα-chloroketoneformsamerearrangementproduct:IntramolecularSN2attack(structuremaintaining):2StevensRearrangementStructuremaintainingThesulfoniumcatio