7.Organometallic Compounds of Group I and II Metals 英文学习材料

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1、7OrganometallicCompoundsofGroupIandIIMetalsIntroductionTheuseoforganometallicreagentsinorganicsynthesishaditsbeginningaround1900whenVictorGrignarddiscoveredthatalkylandarylhalidesreactwithmagnesiummetaltogivehomogeneoussolutionscontainingorganomagnesiumcompound

2、s.The“Grignardreagents”provedtobehighlyreactivecarbonnucleophilesandarestillveryusefulsyntheticreagents.Organolithiumreagentscameintosyntheticusesomewhatlater,butarealsoveryimportantforsynthesis.ThepresentchapterfocusesonGrignardreagentsandorganolithiumcompound

3、s.Wealsoconsiderzinc,cadmium,mercury,indium,andlanthanideorganometallics,whichhavemorespecializedplacesinsyntheticmethodology.Certainofthetransitionmetals,suchascopper,palladium,andnickel,whicharealsoimportantinsyntheticmethodology,arediscussedinChapter8.Thecom

4、positionoftheorganolithiumcompoundsisRLiormoreaccuratelyRLin.TheorganomagnesiumcompoundsareusuallyformulatedasRMgX,withXbeingahalide.TheorganometallicderivativesofGroupIandIImetalsprovidereactivecarbonnucleophiles.ReactivityincreasesintheorderLi

5、X,butthelithiumandmagnesiumreactionsarebyfarthemostcommonlyused.Organo-lithiumandmagnesiumreagentsreactwithpolarmultiplebonds,especiallycarbonylgroups,andprovidesyntheticroutestoavarietyofalcohols.Otherelectrophiles,suchasacylhalides,nitriles,andCO2provideroute

6、stoketonesandcarboxylicacids.619620CHOCO22RMRCO2HCHAPTER7RCH2OHM=Li,MgXR′COYOrganometallicOCompoundsofGroupIR′CHOandIIMetalsorR′CNRCR′RCHOHR′COR′CO2R″2R′R2COHR′2COHR′RTheGroupIIBorganometallicsderivedfromzinc,cadmium,andmercuryareconsiderablylessreactive.Thecar

7、bon-metalbondsinthesecompoundshavemorecovalentcharacterthanforlithiumormagnesiumreagents.Zinc,cadmium,andmercuryaredistinctfromothertransitionmetalsinhavingad10shellinthe+2oxidationstateandtheirreactionsusuallydonotinvolvechangesinoxidationstate.Althoughorganoz

8、incandcadmiumreagentsreactwithacylchloride,reactionswithothercarbonylcompoundsrequireeitherLewisacidsorchelatesascatalysts.Thesecatalyzedreactionsmakeorganozincreagentsparti