Chapter 3-碳碳雙鍵的形成-2013.12

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1、第三章第三章碳碳雙鍵的形成碳碳雙鍵的形成Chapter3FormationofCarbon-CarbonDoubleBonds1碳碳雙鍵的形成一、β－消除反應(yīng)二、順式熱解消除反應(yīng)三、由炔烴制備烯烴四、Wittig反應(yīng)五、Horner-Wadsworth-Emmons反應(yīng)六、烯烴的復(fù)分解反應(yīng)七、Tebbe’s試劑(reagent)八、硒氧化物的分裂2一、β－消除反應(yīng)(β-Eleminationreactions)HX-HXCCCCX=OH,Cl/Br/I,OCOR,OSO2Ar,NR3,SR2,OCSOR,OCSSRSaytzeffruleX=

2、-OH,-OCOR,鹵素,-OSO2Ar,RegioselectivityHofmannruleX=-N+R,-S+R32SyneliminationSaytzeffeliminationsAntieliminationStereoselectivityHofmanneliminationsAntielimination3a)a)E2E2機(jī)理δ?B過渡態(tài)有部分π鍵性鍵性質(zhì)HHBCCCCCCXδ?Xδ?BHBHXδ?X交叉式構(gòu)象負(fù)電荷相距較遠(yuǎn)AntiperiplanarE2消除為為反式共平面反式共平面消除（反式消除）溶劑或堿誘導(dǎo)的鹵代烴或烷基磺

3、酸酯的消除反應(yīng)4b)b)E1E1機(jī)理B:HHCCCCCCX酸摧化的醇脫水反應(yīng)c)E1cB機(jī)理B:HCCCCCCXX季銨鹽的HfHofmann消除反應(yīng)5消除反應(yīng)方向?E2反應(yīng)Saytzeff規(guī)則KOHCH3CH2CHCH3CH3CHCHCH3+CH3CH2CHCH2EtOHCl81%19%?E1cB反應(yīng)Hofmann規(guī)則△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堿H3CCHCH3CCH2CCCCH3+CCH2ClH3CCH3H3CCH3H3CCH319%81%7消除反應(yīng)的立體化學(xué)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較穩(wěn)定反式共平面消除特例：CH3OHC

6、H2CH2NCHCHCHCH223△CH3+CH2CH294%6%10NO2CHNO252O2NCH2CH2NCH3OHO2NCH=CH2+CH3N(C2H5)2+H2OC2H5NO2NO2Hofmann類型的1,6-消除反應(yīng)廣泛用于各種環(huán)蕃化合物的合成:CH3CH3OH2CH3CH2N(CH3)3CH32CH3CH3CH311反式共平面消除OHHMe3NHHPhHNaOEtPhCPhPhCPhMePh快MeHNMeMe3synOHPhHHNMe3HPhNaOEtPhCPhHCPhMePh慢MeHNMeMe3anti無(wú)法反式共平面消除時(shí)，也能

7、順式消除DΔHOHNMe3HHH12?E1反應(yīng)CH3CHHSO3CH324CH3CH2CCH3CH3CHCCH3+CH3CH2CCH2ΔOH主要次要aHSOb4CH3HCH3Hββ'?H2OCH3CH3CH3CH2CCH4CH3CHCCH2CH3CHCCH3+CH3CH2CCH2OHCH3H2SO4CH3CH3ΔCH3OH重排13β－消除反應(yīng)還包括一類aldol產(chǎn)物的脫水OOOHONaOH-H2O+PhCHOPhCH3EtOHPhPhPhPh一鍋合成“查爾酮”Mannich反應(yīng)是一個(gè)非常重要的生成碳碳鍵的反應(yīng)OOOR''2NH△+HCHORR

8、NR''HCl2HClRR'R'R'14二、順式熱解消除反應(yīng)?黃原酸酯受熱分解成烯烴:順式消除SRSCHO△SRCCCC+HSOHCH(CH3)2H△H3CCH3C