Topics in Current Chemistry 357 LeGrande M. Slaughter Editor Homogeneous Gold Catalysis 357 Topics in Current Chemistry Editorial Board: H. Bayley, Oxford, UK K.N. Houk, Los Angeles, CA, USA G. Hughes, CA, USA C.A. Hunter, Sheffield, UK K. Ishihara, Chikusa, Japan M.J. Krische, Austin, TX, USA J.-M. Lehn, Strasbourg Cedex, France R. Luque, C(cid:1)ordoba, Spain M. Olivucci, Siena, Italy J.S. Siegel, Nankai District, China J. Thiem, Hamburg, Germany M. Venturi, Bologna, Italy C.-H. Wong, Taipei, Taiwan H.N.C. Wong, Shatin, Hong Kong Aims and Scope TheseriesTopicsinCurrentChemistry presentscriticalreviews ofthepresent and futuretrendsinmodernchemicalresearch.Thescopeofcoverageincludesallareasof chemical science including the interfaces with related disciplines such as biology, medicineandmaterialsscience. Thegoalofeachthematicvolumeistogivethenon-specialistreader,whetheratthe universityorinindustry,acomprehensiveoverviewofanareawherenewinsightsare emergingthatareofinteresttolargerscientificaudience. Thuseachreviewwithinthevolumecriticallysurveysoneaspectofthattopicand places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years should be presented. A description of the laboratoryproceduresinvolvedisoftenusefultothereader.Thecoverageshouldnot be exhaustive in data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the informationpresented. Discussionofpossiblefutureresearchdirectionsintheareaiswelcome. Reviewarticlesfortheindividualvolumesareinvitedbythevolumeeditors. Readership:researchchemistsatuniversitiesorinindustry,graduatestudents. Moreinformationaboutthisseriesat http://www.springer.com/series/128 LeGrande M. Slaughter Editor Homogeneous Gold Catalysis With contributions by A. Aponick (cid:1) O.N. Faza (cid:1) M.R. Gagne´ (cid:1) G.B. Hammond (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) A.C. Jones C.S. Lopez D. Malhotra V. Michelet (cid:1) (cid:1) (cid:1) P.H.S. Paioti S. Shin D. Weber B. Xu Editor LeGrandeM.Slaughter DepartmentofChemistry UniversityofNorthTexas Denton,Texas USA ISSN0340-1022 ISSN1436-5049 (electronic) TopicsinCurrentChemistry ISBN978-3-319-13721-6 ISBN978-3-319-13722-3 (eBook) DOI10.1007/978-3-319-13722-3 LibraryofCongressControlNumber:2015936667 SpringerChamHeidelbergNewYorkDordrechtLondon ©SpringerInternationalPublishingSwitzerland2015 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpartof the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilarmethodologynowknownorhereafterdeveloped. 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Printedonacid-freepaper Springer International Publishing AG Switzerland is part of Springer Science+Business Media (www.springer.com) Preface Theriseofhomogeneousgoldcatalysisisthestoryofalong-neglectedmetalboldly defyingexpectations.Alongwithageneralreputationforinertness,goldpossesses two common oxidation states which have historically been overlooked as too uninteresting(AuI)ortoounstable(AuIII)towarrantseriousstudybymostorgan- ometallic chemists. Despite significant activity in the area of heterogeneous gold catalystsfromthe1970sonward,andatrickleofseminalreportsofhomogeneous goldcatalysisbyIto,Hayashi,andUtimotointhe1980sand1990s,thelatterarea didnotbegintoblossomuntiltheworkofTelesandHashmiin1998–2000unveiled thepotentialofthefield.Itisnowwellrecognizedthatgold(inparticularAuI)isa potent,“soft”carbophilicLewisacid,withanabilitytoactivatecarbon–carbonπ- bonds toward nucleophilic attack which parallels the reactivity of other late tran- sition metals such as platinum, palladium, and mercury. It is also clear that gold often outshines its metallic neighbors by activating π-bonds under exceptionally mild conditions and by channeling these transformations into unique modes of reactivity which are particularly suited for the synthesis of complex organic molecules. Such is the pace of progress in this field that the many excellent reviews available in the literature are in frequent need of updates. The purpose of this volumeistohighlightsomekeysubareasofhomogeneousgoldcatalysisthathave spurredsignificantadvancesinthefieldinthepast3–5years.Thetopicshavebeen chosen in recognition of two equally powerful forces that have driven the recent evolution of gold catalysis: an increasing need for synthetic methods that deliver complex organic structures, and the renaissance of fundamental organometallic gold chemistry. The authors are active researchers who have made substantial contributionstotheareasreviewedintheirrespectivechapters. The volume begins with a chapter by Malhotra, Hammond, and Xu, which highlights the interplay of ligand effects, substrate structure and mechanism in goldcatalysis,usingspecificexamplesofliganddesignandreactionsmediatedby gold–oxonium intermediates. Shin reviews reactions in which alkynes serve as synthons for reactive gold carbene intermediates, an approach that has yielded v vi Preface numerous routes to complex organic molecules without the need for problematic diazo reagents as carbene precursors. Paiote and Aponick provide an account of gold-catalyzedtransformationsofunsaturatedalcohols,animportantreactionclass in which π-activation leads to formal substitution processes via loss of H O. 2 A chapter by Michelet surveys the rich area of gold-catalyzed domino processes, in which gold-mediated reactions trigger multistep transformations which can generate significant molecular complexity. On the organometallic side, Jones criticallyreviewsrecentstudiesofthestructureandreactivityofgoldπ-complexes whicharemodelintermediatesforgold-catalyzedprocesses,andWeberandGagne´ summarizethecurrentstateofknowledgeoftheeffectsofaurophilicattractionon gold catalysis. A chapter by Faza and L(cid:1)opez on computational approaches to the studyofhomogeneousgoldcatalysiscompletesthevolume.Thelatterissuretobe a valuable resource for chemists working in the gold catalysis arena, given the increasinglyindispensableroleofcomputationalchemistryindecipheringcatalytic reactionmechanismsandthedifficultyofchoosingtheproperapproachamongthe growingarsenalofavailablemethods. It is hoped that this volume will serve as a valuable and timely resource for chemistsactivelypursuingresearchinbothsyntheticapplicationsofhomogeneous goldcatalysisandfundamentalorganogoldchemistry,aswellasforthosewhoare simplyinterestedinfollowingtherichandgrowingliteratureofthisfield. Denton,TX,USA LeGrandeM.Slaughter September2014 Contents LigandDesigninGoldCatalysisandChemistryofGold–Oxonium Intermediates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 DeepikaMalhotra,GeraldB.Hammond,andBoXu Gold-CatalyzedCarbeneTransferReactions. . . . . . . . . . . . . . . . . . . . . 25 SeunghoonShin Gold-CatalyzedTransformationofUnsaturatedAlcohols. . . . . . . . . . . 63 PauloH.S.PaiotiandAaronAponick Gold-CatalyzedDominoReactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Ve´roniqueMichelet Goldπ-ComplexesasModelIntermediatesinGoldCatalysis. . . . . . . . 133 AmandaC.Jones AurophilicityinGold(I)Catalysis:ForBetterorWorse?. . . . . . . . . . . 167 DieterWeberandMichelR.Gagne´ ComputationalApproachestoHomogeneousGoldCatalysis. . . . . . . . . 213 OlallaNietoFazaandCarlosSilvaL(cid:1)opez Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 vii TopCurrChem(2015)357:1–24 DOI:10.1007/128_2014_592 #SpringerInternationalPublishingSwitzerland2014 Publishedonline:24February2015 Ligand Design in Gold Catalysis and Chemistry of Gold–Oxonium Intermediates DeepikaMalhotra,GeraldB.Hammond,andBoXu Abstract Goldcatalysisisconsideredoneofthemostimportantbreakthroughsin organicsynthesisduringthelastdecade.Manygold-catalyzedreactionssufferfrom high catalyst loading, which is a serious limitation on the application of gold catalysisinlargerscale synthesis.Becauseligandsplay amajor roleinthetuning of reactivity of transition metal catalysts, there has been an increased effort on rationallyunderstandingligandeffectsingoldcatalysisandusingarationalligand design to achieve higher efficiency. In the first part of this chapter, selected examples of ligand design in gold catalysis are discussed. In the second part, the chemistryofgold–oxoniumintermediateisexamined.Anoxoniumintermediateis generatedwhenaoxygennucleophile(ketone,aldehyde,orether)attacksacationic gold-activatedmultiplebond.Thisoxoniumintermediate,beingahighlyenergetic species, has the potential to undergo further transformations such as electron transfer/rearrangement/protodeaurationtoformdiverseproducts. Keywords Benzannulations(cid:129)Cationicgold catalysis (cid:129)Ligand design(cid:129)Oxonium intermediates Contents 1 LigandDesigninCationicGoldCatalysis.................................................. 2 1.1 Introduction............................................................................. 2 1.2 LigandEffectsinGoldCatalysis...................................................... 2 1.3 SelectedExamplesofLigandDesigninGoldCatalysis.............................. 4 2 ChemistryofGold–OxoniumIntermediates................................................. 11 2.1 Introduction............................................................................. 11 2.2 ChemistryofGold–OxoniumIntermediatesDerivedfromCarbonylCompounds.. 11 2.3 ChemistryofaGold–OxoniumIntermediateDerivedfromEthers/Epoxides....... 16 References........................................................................................ 22 D.Malhotra,G.B.Hammond(*),andB.Xu(*) DepartmentofChemistry,UniversityofLouisville,Louisville,KY40292,USA e-mail:[email protected];[email protected] 2 D.Malhotraetal. 1 Ligand Design in Cationic Gold Catalysis 1.1 Introduction Therehasbeenanexponentialincreaseinthenumberofstudiesonhomogeneous goldcatalysisduringthepastdecade[1–12].Cationicgoldspeciesareregardedas the most powerful catalysts for the electrophilic activation of alkynes toward a variety of nucleophiles [2, 4–10, 13, 14]. The reason for this success can be attributedtothelowerLUMOandpoorback-donationofthecationicgoldspecies [15–18].Ontheotherhand,thelowturnovernumbersobservedingold-catalyzed reactionshavelimitedtheapplicabilityofgoldcatalystsinfieldssuchasmedicinal chemistry and material synthesis. Gold being a precious metal, it is difficult to recycleaftereachreaction;thecommonpracticeistouse5%loading,whichmakes its use often impractical in larger scale synthesis. In contrast, in many palladium- catalyzedcouplingreactions, suchastheSuzukireaction, thecatalystloadinghas beenreducedtoppmlevels[19]. Ligandsplayamajorroleinthetuningofreactivityoftransitionmetalcatalysts [20–22].Initially,becauseofthecomplexityofgold-catalyzedreactions,arational understandingofligandeffectslaggedbehindthedevelopmentofalargenumberof gold-catalyzedtransformations,andthedevelopmentofnewcatalystsandreactions mostly relied upon trial and error [5]. However, in the last few years, more effort wasmadetoachievearationalunderstandingofligandeffectsingoldcatalysisand the use of a rational ligand design to achieve higher efficiency (TON). There has alsobeenprogressinthedesignofchiralligandsforenantioselectivegoldcatalysis, but,becauseofpagelimitations,thedevelopmentofchiralligandsisnotcoveredin thischapter[23]. 1.2 Ligand Effects in Gold Catalysis 1.2.1 LigandEffectsinEachStageoftheGoldCatalyticCycle Hammond and Xu conducted a relatively comprehensive investigation of ligand effects in gold catalysis in 2012 [24]. It is generally accepted that most gold- catalyzed reactions go through three major stages (Scheme 1). In stage 1, a nucleophileattacksan[L–Au]+-activatedalkyne(oralkene)toformatrans-alkenyl goldcomplexintermediateB(oranalkylgoldcomplexinthecaseofalkenes).In stage 2, the resulting vinyl complex B reacts with an electrophile (E+), usually a proton, to yield the final product via protodeauration, which also regenerates the cationic gold species (Scheme 1). Additionally, in almost all gold-catalyzed reac- tions,decayordeactivationofthegoldcatalysttakesplace(stage3)[25].Insome gold-catalyzed reactions, the formation of off-cycle gold species such as bis-Au- vinyl species D was observed [26]. As in the decay of cationic gold catalysts, off-cyclegoldspeciesalsoreducetheturnoverofproductformation.