Chapter 3-碳碳双键的形成-2013.12

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1、第三章第三章碳碳双键的形成碳碳双键的形成Chapter3FormationofCarbon-CarbonDoubleBonds1碳碳双键的形成一、β－消除反应二、顺式热解消除反应三、由炔烃制备烯烃四、Wittig反应五、Horner-Wadsworth-Emmons反应六、烯烃的复分解反应七、Tebbe’s试剂(reagent)八、硒氧化物的分裂2一、β－消除反应(β-Eleminationreactions)HX-HXCCCCX=OH,Cl/Br/I,OCOR,OSO2Ar,NR3,SR2,OCSOR,OCSSRSaytzeffruleX=

2、-OH,-OCOR,卤素,-OSO2Ar,RegioselectivityHofmannruleX=-N+R,-S+R32SyneliminationSaytzeffeliminationsAntieliminationStereoselectivityHofmanneliminationsAntielimination3a)a)E2E2机理δ−B过渡态有部分π键性键性质HHBCCCCCCXδ−Xδ−BHBHXδ−X交叉式构象负电荷相距较远AntiperiplanarE2消除为为反式共平面反式共平面消除（反式消除）溶剂或碱诱导的卤代烃或烷基磺

3、酸酯的消除反应4b)b)E1E1机理B:HHCCCCCCX酸摧化的醇脱水反应c)E1cB机理B:HCCCCCCXX季铵盐的HfHofmann消除反应5消除反应方向¾E2反应Saytzeff规则KOHCH3CH2CHCH3CH3CHCHCH3+CH3CH2CHCH2EtOHCl81%19%¾E1cB反应Hofmann规则△CH3CH2CH2CHCH3CH3CH2CHCHCH3+CH3CH2CH2CHCH2+(CH3)3NN(CH3)3OH2%98%6KOHCH3CH2CHCH3CH3CHCHCH3+CH3CH2CHCH2EtOHCl81%19%

4、δ−HOHaaOHbCH3CHCHCH3CH3CHCHCH3HHδ−Clδ−CH3CHCHCH2OHHClbCH3CH2CCH2CH3CH2CHCH2δ−Cl反式共平面消除特例：CH3CHCH33H3CCH2CCH3碱H3CCHCH3CCH2CCCCH3+CCH2ClH3CCH3H3CCH3H3CCH319%81%7消除反应的立体化学PhPhββHCPhH3CHHCH3KOEt3CαorαBrHHBrEtOHCHPhPhPhPhEtOEtOHPhβHPhHPhPhH3CHHαCCBrHPhPhCH3H3CHH3CBrPhBr8MeHClHCH

5、(CH3)2HHHClHNaOEtHMe慢MeCH(CH3)2HHHHCH(CH3)2H唯一HHCH(CH3)2NaOEtHHH+MeCH(CH3)2Me快MeCH(CH3)2HClH25%75%CH(CH3)2HHNaOEtHCH(CH3)2HMeHOEtMeHH快ClH9△CH3CH2CHCH3CH3CH2CHCH2+CH3CHCHCH3+(CH3)3NN(CH3)3OH主N(CH3)3N(CH3)3N(CH3)3N(CH3)3HHH3CHHCH3HHHCH3HCH3HCH3HCH2CH3CH3HHH较稳定反式共平面消除特例：CH3OHC

6、H2CH2NCHCHCHCH223△CH3+CH2CH294%6%10NO2CHNO252O2NCH2CH2NCH3OHO2NCH=CH2+CH3N(C2H5)2+H2OC2H5NO2NO2Hofmann类型的1,6-消除反应广泛用于各种环蕃化合物的合成:CH3CH3OH2CH3CH2N(CH3)3CH32CH3CH3CH311反式共平面消除OHHMe3NHHPhHNaOEtPhCPhPhCPhMePh快MeHNMeMe3synOHPhHHNMe3HPhNaOEtPhCPhHCPhMePh慢MeHNMeMe3anti无法反式共平面消除时，也能

7、顺式消除DΔHOHNMe3HHH12¾E1反应CH3CHHSO3CH324CH3CH2CCH3CH3CHCCH3+CH3CH2CCH2ΔOH主要次要aHSOb4CH3HCH3Hββ'−H2OCH3CH3CH3CH2CCH4CH3CHCCH2CH3CHCCH3+CH3CH2CCH2OHCH3H2SO4CH3CH3ΔCH3OH重排13β－消除反应还包括一类aldol产物的脱水OOOHONaOH-H2O+PhCHOPhCH3EtOHPhPhPhPh一锅合成“查尔酮”Mannich反应是一个非常重要的生成碳碳键的反应OOOR''2NH△+HCHORR

8、NR''HCl2HClRR'R'R'14二、顺式热解消除反应•黄原酸酯受热分解成烯烃:顺式消除SRSCHO△SRCCCC+HSOHCH(CH3)2H△H3CCH3C