Domino process reactions in organic synthesis

Dominoprocessreactionsinorganicsynthesis导师：高建荣金红卫有机化学吴志2008.4WhatisDomino?多米诺骨牌和多米诺骨牌效应多米诺骨牌（domino）是一种用木制、骨制或塑料制成的长方形骨牌。玩时将骨牌按一定间距排列成行，轻轻碰倒第一枚骨牌，其余的骨牌就会产生连锁反应，依次倒下。这种效应的物理道理是：骨牌竖着时，重心较高，倒下时重心下降，倒下过程中，将其重力势能转化为动能，它倒在第二张牌上，这个动能就转移到第二张牌上，第二张牌将第一张牌转移来的动能和自己倒下过程中由本身具有的重力势能转化来的动能之和，再传到第三张牌上。。。。。。所以每张牌倒下的时候，具有的动能都比前一块牌大，因此它们的速度一个比一个快，也就是说，它们依次推倒的能量一个比一个大。Whatisdominoreaction?Inanidealprocedure,theentiretransformationshouldberunwithouttheadditionofanyfurtherreagentsorcatalysts,andwithoutchangingthereactionconditions.Wehavedefinedthistypeoftransformationasa“dominoreaction”or“dominoprocess”.Suchaprocesswouldbethetransformationoftwoormorebond-formingreactionsunderidenticalreactionconditions,inwhichthelattertransformationstakeplaceatthefunctionalitiesobtainedintheformerbondformingreactions.ThreeelementsforDominoprocessreactionUnderidenticalreactionconditionsTwoormorebond-formingFunctionalitiesobtainedintheformerbond-formingAvisibleexampleofthistypeisthehighlystereoselectiveformationoflanosterol(羊毛甾醇)(0-6)from(S)-2,3-oxidosqualene(2,3-环氧三十碳六烯)(0-5)inNature,whichseemsnottofollowaconcertedmechanism(Scheme0.2).K.U.Wendt,G.E.Schulz,E.J.Corey,D.R.Liu,Angew.Chem.Int.Ed.2000,39,2812−2833Likedominostones,whereonestonetipsoverthenext,whichtipsthenext,andthenext...suchthattheyallfalldowninturn.Whywesearchfordominoprocessreactions?•Theuseofdominoreactionshasthesemainadvantages.•First,tothechemicalindustry,asthecostsnotonlyforwastemanagementbutalsoforenergysuppliesandmaterialsarereduced.•Second,thebeneficialeffectontheenvironment,asdominoreactionshelptosavenaturalresources.•Third,time-resolvedtransformationsItis,therefore,notsurprisingthatthisnewconcepthasbeenadoptedveryrapidlybythescientificcommunity.Classificationofdominoprocessreactions•1CationicDominoReactions•2AnionicDominoReactions•3RadicalDominoReactions•4PericyclicDominoReactionsTheterminationofcationiccyclizationsbytheuseofpinacolrearrangementshasshowntobeapowerfultoolfordevelopingstereoselectivering-formingdominoreactions.Duringthepastfewyears,theOvermangrouphasinvestedmucheffortinthedesignoffascinatingdominoPrinscyclization/pinacolrearrangementsequencesforthesynthesisofcarbocyclicandheterocycliccompounds,especiallywithregardtotarget-directedassemblyofnaturalproductsCationicDominoReactionsLewisacid-inducedring-expandingcyclopentane（环戊烷）annulation（环壮物）ofthe1-alkenylcycloalkanylsilylether1-8.Theoxeniumion1-9producedperformeda6-endoPrinscyclizationwiththetetheredalkenemoiety,givingcycliccarbocation1-10.thelatterdirectlyunderwentapinacolnrearrangementresultingintheformationofcycloalkanone1-11.Aone-carbonexpansionofthesubstrate1-8.Triflic(三氟甲磺酸)anhydride(酐)andDTBMP,pyrrolidineamide1-20wasconvertedintotheketeniminium(烯酮亚胺)ion1-22,Cyclizationthroughachairliketransitionstateprovidedcarbocation1-23,apinacolrearrangementtogiveenamine1-24.AnionicDominoReactionsAnionicdominoprocessesarethemostoftenencountereddominoreactionsinthechemicalliterature.Thewell-knownRobinsonannulation,doubleMichaelreaction,Pictet−Spenglercyclization,reductiveamination,etc.,allfallintothiscategory.Theprimarystepinthisprocessistheattackofeitherananion(e.g.,acarbanion,anenolate,oranalkoxide)ora“pseudo”anionasanunchargednucleophile(e.g.,anamine,oranalcohol)ontoanelectrophiliccenter.Abondformationtakesplacewiththecreationofanew“real”or“pseudo-anionic”functionality,whichcanundergofurthertransformations.ThesequencecanthenbeterminatedeitherbytheadditionofaprotonorbytheeliminationofanX−group.Anionic/AnionicProcesses---Dominotransformationscombiningtwoconsecutiveanionicstepsexistinseveralvariants,butthemajorityofthesereactions0000000isinitiatedbyaMichaeladdition.Accordingly,numerousexamplesofMichael/Michael,Michael/aldol,Michael/Dieckmann,aswellasMichael/SNtypesequenceshavebeenfoundintheliterature.Schneiderandcoworkersproducedfunctionalizedenantiopurecyclohexanesoftype2-94,startingfrom2-93andacupratewithexcellentselectivityof95:5(Scheme2.21).ThestereochemicaloutcomecanbeexplainedtakingtheTS2-95andTS2-96intoaccount.Anionic/AnionicProcessesRadicalDominoReactionsUsually,free-radicaldominoprocessesarecharacterizedbyasequenceofintramolecularsteps,theoverallpropagationcoordinatebeingunimolecular(excludinginitiationandterminationsteps)(Scheme3.1)Themostrelevantcounterpartoftheseunimolecularreactionsisrepresentedbyreactionsinwhichonestep−inmanycasesthefirst−isanintermolecularradicaladditiontoanappropriatefunctionalizedacceptor(Scheme3.2).Iftheattackingradicalcontainsanadequatelyplacedradicalacceptorfunctionality,thepossibilityofaradicalcycloadditionisprovided,offeringaproceduretoconstructcyclicproductsfromacyclicprecursors.Forthistypeofring-formingprocess,inwhichtwomolecularfragmentsareunitedwiththeformationoftwonewbonds,theterm“annulation”hasbeenadopted(Scheme3.3).A.J.McCarroll,J.C.Walton,J.Chem.Soc.PerkinTrans.12001,3215−3229.useoftheoxidizingpropertiesofceric(铈)ammoniumnitrate(CAN)(硝酸铵)tofurnishradical-cationspecies3-2outofopticallyactive1-arylthiobicyclo[4.1.0]heptane(庚烷)3-1bysingleelectrontransfer(SET).Y.Takemoto,T.Oh