资源描述：
《015.3 Boschke F.L. Dynamic Stereochemistry (1971)》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、AUene-OlefinandAllene-AlleneCycloadditionsMethylenecyclobutaneand1,2-DimethylenecyclobutaneDegenerateRearrangementsProf.J.E.BaldwinandMr.R.H.FlemingDepartmentofChemistry,UniversityofOregon,Eugene,OR97403,USAContentsI.Introduction..................................................281II.Allene-
2、OlefinCycloadditions....................................282III.MethylenecyclobutaneRearrangements..........................286IV.Allene-AlleneCycloadditions....................................288V.1,2-DimcthylenecyclobutaneRearrangements.....................294VI.MolecularOrbitalCalculations
3、..................................297VII.Concertedness.................................................300VIII.DiscussionandConclusions.....................................304IX.References...................................................307I.IntroductionAllene-olefinandallene-allenethermal
4、cycloadditionsprovideusefulsyntheticroutestomethylenecyclobutanesand1,1-dimethylenecyclo-butanes.Thehistoricaldevelopment,manypracticalexploitations,andmechanisticassessmentsofthesereactionsweresummarizedbyRobertsandShartsin19629s)andcoveredinpartinsubsequentreviewsrelatedtoallenechemistry23
5、,54,79,81,93,125,141).CH2=c=CH2+CH2=CH2=[~CH2=C=CH2+CH2=C=CH2~[~Withinthepastfewyearsdegeneratevalenceisomerizationsofmethyl-enecyclobutaneand1,2-dimethylenecyelobutanehavebeendetected.281J.E.BaldwinandR.H.FlemingI~cCD2,D~CH2D2.~D~CH2HCNewkineticandstereochemicalinformationonthesetwocyclo-ad
6、ditionsandtwodegeneratemolecularrearrangementshasbecomeavailable,andacomprehensivetheoryrelatingsomegeneralpostulatesonconservationoforbitalsymmetryduringconcertedchemicalprocessestotheirstereochemicalfeatureshasbeenadvancedandimpressivelydeveloped113,142).Thesenewdevelopmentsplaceallene-ole
7、finandaUene-allenethermalcycloadditionsinanewcontextframedbythequestions:Aretherereactiveintermediatesseparatingreactantsandproductsinthecyclo-additions,orinthedegeneraterearrangements?Mighttherebeacommonreactiveintermediatefortheallene-olefinaddit
