Heck反应机理及示例.doc

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1、Heck反应的机理及示例机理：Heck反应的机理有一定的规律，通常认为反应共分四步：（a）氧化加成（Oxidativeaddition）:RX(R为烯基或芳基，X=I>TfO>Br>>Cl)与Pd0L2的加成，形成PdⅡ配合物中间体；（b）配位插入（Cordination-insertion）:烯键插入Pd-R键的过程；（c）β-H的消除；（d）催化剂的再生：加碱催化使重新得到Pd0L2。示例：Astirredsolutionof1(98mg,0.19mmol),triethylmine(0.32mL,2.3mmol)andcataly

2、tictetrakis(triphenylphosphine)palladium(0)(ca.5mg,4μmol)in2.4mLofacetonitrilewasheatedat80℃inasealedtubeunderanargonatmospherefor10h.Thereactionmixtureturneddarkorangeafterca.10min,andthecatalystplatedoutonthewallsofthetubeasashinylayerofpalladiummetaluponcompletionofth

3、ereaction.Thereactionmixturewascooledtoroomtemperature;thereactionwasquenchedwithaqueousNaHCO3(15mL),andthemixturewasextractedwithEtOAc(4×10mL).TheorganicextractswerewashedwithaqueousNaHSO3(1×15mL),water(1×15mL),andbrine(1×15mL)anddriedoverMgSO4.Filtration,concentration,

4、andpurificationoftheorangeresiduebyflashcolumnchromatography(45:55Et2O/hexanes)gave66mg(90%)of19asacolorlesssolid:mp193-194℃;Rf=0.29(8:2Et2O/hexanes).