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1、主 講 教 師 : 劉 培 念 羊群效應(yīng)地獄里發(fā)現(xiàn)石油了;群眾的眼睛不是血亮的;毛毛蟲習(xí)慣;盲從與理性;尋找好的領(lǐng)頭羊;不走尋常路; 自己創(chuàng)造未來; 碳正離子的重排反應(yīng) 碳正離子的1,5-負(fù)氫遷移 碳正離子的1,2-遷移1,2-遷移與離去基團的離去是協(xié)同作用XX Beckmann重排 練習(xí) Pinacol重排 練習(xí) Ph-的重排加成消除機理: C(sp3)-X的取代與消除反應(yīng)通過SN1與SN2機理的取代反應(yīng)SN1機理: 酸性條件下SN1機理的反應(yīng) 練習(xí) 酸性條件下SN2機理的反應(yīng) 那個機理更合理? 對雜原子的取代反應(yīng) 一個特例(R, R) (R, R) (S, S) 通過E1機理進(jìn)行的消除反應(yīng)
2、 練習(xí) 對親核性的C=C的親電加成反應(yīng)(烷基或雜原子取代烯烴) (與N, O相連的烯烴尤其活潑)(X:無機酸、有機酸、醇、水) 范例(Markovnikovs rule) Markovnikovs rule is simply an application of the Hammond postulate: the faster reaction is the one that leads to the intermediate lower in energy. 練習(xí) C=C鍵與含有孤對電子的親電性雜原子的反應(yīng) (X為I, Br時較穩(wěn)定)(X為Cl時較穩(wěn)定) 練習(xí) 親核性C=C鍵的取代反應(yīng)親電
3、性苯環(huán)取代反應(yīng)(與HOCOOH類似) 苯環(huán)的取代基效應(yīng) 苯環(huán)的取代基效應(yīng) 苯胺通過苯重氮鹽的取代反應(yīng) 苯重氮鹽的還原(SRN1機理) 苯重氮鹽與銅(I)化合物的反應(yīng)(SRN1機理) 苯重氮鹽與水、 BF4-的反應(yīng)Because neither H2O nor BF4- are oxidizable enough to transfer an electron to the aryldiazonium ion, only SN1 mechanisms are reasonable for these reactions. Sakurai reaction 對親電性鍵的親核加成與取代反應(yīng)雜原子親核
4、試劑的反應(yīng): 酮在酸性或堿性條件下的變化反應(yīng) 酮的還原胺化反應(yīng) 對親電性鍵的親核加成與取代反應(yīng)碳原子親核試劑的反應(yīng):(Robinson 閉環(huán)反應(yīng)) Mannich 反應(yīng) Mannich 反應(yīng)的另兩種可能機理? Mukayama醛醇反應(yīng) Summary Summary 第 四 章 周 環(huán) 反 應(yīng) 1、基礎(chǔ)知識 A pericyclic reaction is a reaction in which bonds are formed or broken at the termini of one or more conjugated systems. The electrons move arou
5、nd in a circle, all bonds are made and broken simultaneously, and no intermediates intervene.Typical reactionsRegioselectivityStereoselectivityStereospecificity 4.1.1 Classes of Pericyclic Reactionsn Electrocyclic reactions (ring openings or ring closings), n Cycloadditions n Sigmatropic rearrangeme
6、ntsn Ene reactions. Electrocyclic reactions Cycloadditions Cheletropic reactionsCycloadditions Sigmatropic rearrangements Sigmatropic rearrangements Sigmatropic rearrangements Ene Reaction 四種周環(huán)反應(yīng)總結(jié) 立體專一性 Polyene MOsWoodwardHoffmann rules Polyene MOs Polyene MOs Polyene MOs 2、電環(huán)化反應(yīng)2.1、典型反應(yīng) 2.1、典型反應(yīng) 2
7、.1、典型反應(yīng) 2.1、典型反應(yīng) 練習(xí)4.1 2.1、典型反應(yīng) 2.1、Favorskii rearrangement 2.1、Favorskii rearrangement 練習(xí) 練習(xí) 4.2.2 Stereospecificity 1,3,5-hexatrienes 偶 熱 順奇 熱 反偶 光 反奇 光 順 The WoodwardHoffmann rules apply only to concerted, pericyclic reactions. A reaction can be forced to proceed through the higher energy TS if the lower energy one is raised prohibitively high in energy by geometric constraints. 4.2.3 Stereoselectivity 4.3 Cycloadditions4.3.1 Typical Reactions4.3.1.1 The DielsAlder Reaction