有機(jī)化學(xué)中的重排反應(yīng)

1、Chapter 11 Rearrangements ReactionsBonding weaker than covalentStereochemistryCarbocations,Carbanions, Free radicals, Carbenes, and NitrenesMechanisms and methods of determing themEffects of structure on reactivityNucleophilic subsitutionElectrophilic substitutionFree radical substitutionAddition re

2、actionsEliminations RearrangementsOxidations and reductionsABYABYMECHANISMSNucleophilic RearrangementsWhitmore 1,2-shiftOpen sextetStep I. Creation of a system with open sextet:1. Formation of a CarbocationCRCOHH+CRCOH2+CRC2. Formation of a NitreneRNNCONRNCO+N2Step II. Migration Step III. The migrat

3、ion origin (A) acquires an octetRearrangement with substitution (combinations with a nucleophile)Rearrangement with elimination (loss of H+)The Actual Nature of the MigrationPhCPhOHCHNH2MeHONOPhCOCPhHMe(+)(-)The configeration of W is retainedInversion of B ABXRABRABRthird stepRacimation is found at

4、B:Inversion occurs at B:SN1-likeSN2-likeWhen B is a teriary atom or has one aryl group and at least one other alkyl or aryl group SN1-likeIn other case, SN2-like1.2. When R is aryl or vinyl, the intermediate is probably formed H2CCH2CH3CCH3CD2CH3CH3CH2CCD2CH3CH3CD2CCH3CH3CH3CH2CCH3CD2HWhen R is alky

5、l, the intermediate is not formedABRYABRYInversion at A and BInversion at A onlyCCHPhPh HOH OHCCHPhPh HOHH+CCHPhPhOHHCCHPhPhHOCCHPhPhOHHCCHPhPhHOMigratory AptitudesCCHPhMeMeCH2H+CCMeMeMePhCCPhMeMeMe141414CCHPhMeMeOTsMeCCPhMeMeMe1414Memory effectsLonger Nucleophilic RearrangementHODMeOHH+H2ODMeOHDMeO

6、HMeOHD-H+MeODFree-Radical RearrangementsABYABYCCHCCH2CCCCElectophilic RearrangementsABYABYPhCCH2PhPhCCH2PhPhPh例例Reaction1,2-rearrangementsA. Carbon to carbon migrations of R, H, and ArWagner-Meerwein and related Reactions:OHH+Brcat AlBr3NO2CH3HHHHAlBr4CH3HHHAlBr4H-AlBr3BrMeHOMeMeMeHHMeHMe12345678910

7、1112131415161718192122MeMe123456789101112131415161718192122MeMeHHH+t-BuClt-BuClROHpyridineSOCl2RRHNRThe Pinacol Rearrangementsemi-pinacol rearrangementPhCPhOHCHNH2MeHONOPhCOCPhHMe(+)(-)Expansion and contraction of rings Tiffeneau-Demjanov O1)HCNor CH3NO2/NaOH2) LiAlH4OHNH2NaNO2HClOHNN-N2HOOH-H+OOClRO-HHOR+OClORO-OOROROHORROHORO+RO-ROR1HR2-ROR1RORROHRR2LiOverman rearrangement :RR1OHcat NaHCl3CCNRR1OCCl3HNRR1OCCl3HNH-RR1ONCCl3RR1OCCl3NRR1O+HRR1OCCl3HN3,3Novel Catalysts for the