Guanidines as Reagents and Catalysts II PDF
Preview Guanidines as Reagents and Catalysts II
Topics in Heterocyclic Chemistry 51 Series Editors: Bert Maes · Janine Cossy · Slovenko Polanc Philipp Selig Editor Guanidines as Reagents and Catalysts II 51 Topics in Heterocyclic Chemistry SeriesEditors: Bert Maes, Antwerp, Belgium Janine Cossy, Paris, France Slovenko Polanc, Ljubljana, Slovenia Editorial Board: D. Enders, Aachen, Germany S.V. Ley, Cambridge, UK G. Mehta, Bangalore, India R. Noyori, Hirosawa, Japan L.E. Overman, Irvine, CA, USA A. Padwa, Atlanta, GA, USA Aims and Scope The series Topics in Heterocyclic Chemistry presents critical reviews on present andfuturetrendsintheresearchofheterocycliccompounds.Overallthescopeisto covertopicsdealingwithallareaswithinheterocyclicchemistry,bothexperimental andtheoretical,ofinteresttothegeneralheterocyclicchemistrycommunity. The series consists of topic related volumes edited by renowned editors with contributionsofexpertsinthefield. More information about this series at http://www.springer.com/series/7081 Philipp Selig Editor Guanidines as Reagents and Catalysts II With contributions by V. del Amo (cid:1) R.M. Capita˜o (cid:1) C. Concello´n (cid:1) C. von Eßen (cid:1) C.R. Go¨b (cid:1) E.R.P. Gonza´lez (cid:1) S. Herres-Pawlis (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) H.-J. Himmel A. Hoffmann J. Mannsperger A. Metz I.M. Oppel (cid:1) T. Ro¨sener (cid:1) R.D.E. Santo (cid:1) J. Stanek Editor PhilippSelig PatheonInc. Linz,Austria ISSN1861-9282 ISSN1861-9290 (electronic) TopicsinHeterocyclicChemistry ISBN978-3-319-53012-3 ISBN978-3-319-53013-0 (eBook) DOI10.1007/978-3-319-53013-0 LibraryofCongressControlNumber:2017936046 ©SpringerInternationalPublishingAG2017 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. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexempt fromtherelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. Thepublisher,theauthorsandtheeditorsaresafetoassumethattheadviceandinformationinthis book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained hereinor for anyerrors oromissionsthat may havebeenmade. Thepublisher remainsneutralwith regardtojurisdictionalclaimsinpublishedmapsandinstitutionalaffiliations. Printedonacid-freepaper ThisSpringerimprintispublishedbySpringerNature TheregisteredcompanyisSpringerInternationalPublishingAG Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland Preface Guanidines, the all-aza analogues ofcarbonic acids, representa fascinating group ofmoleculeswithuniquechemicalandphysicalproperties.Justasthewell-known amidines,guanidinesareexceedinglystrongBrønstedbasesandarethereforeeven referred to as “superbases.” Moreover, guanidines can exhibit strong Lewis-basic propertiesandthusserveaselectron-pairdonorsandligands.Afterprotonation,the highlystabilizedguanidiniumcationisoftenusedasapowerful,bidentateH-bond donor,capableoftightbindingandactivationofavarietyofH-bondacceptorssuch as carbonyl groups. Finally, guanidinium cations can also be regarded as Lewis- acidicspecieswhichcanactasp-Lewisacids. Guanidines and their corresponding protonated species are thus capable of exhibitingallfourbasicchemicalfunctionalities:freebasesareLewisandBrønsted basic,whilecationsareLewisandBrønstedacidic,allconnectedbyasimpleproton transfer. Besides this obvious potential for synthetic applications, guanidines are also a challengingtargetforsyntheticendeavors,mainlyduetotheirhighlybasiccharac- ter.InthefirstvolumeofGuanidinesasReagentsandCatalysts,wethuswantedto open with an overview of Prof. Rozas, which introduces the reader to principal techniques for guanidine synthesis and offers a first glimpse on the potential of guanidinesinbiologicalapplications. Amain topic of Vol.I concerns the use ofguanidines assynthetic reagentsor, more specifically, as organocatalysts. We are introduced into this topic with a chapter by Prof. Ishikawa, a pioneer of guanidine organocatalysis and also the inventor of one of the very rare examples of a commercially available guanidine catalyst, “Ciba-G.” Ciba-G is also already highlighting the importance of multi- functional activations in guanidine organocatalysis, a most important concept, whichisfurtherillustratedbytheworksofProf.Takemotointhefollowingchapter. Turningthefocusfromcatalyststructurestosyntheticapplications,Prof.Najera willelaborateonapivotalguanidine-catalyzedreaction,i.e.,theMichaeladdition, which makes formidable use of both the Brønsted basic and the H-bond donating properties of the guanidine and guanidinium cation. In the following chapter, v vi Preface structuresofguanidineorganocatalystsaretakentothenextlevelbyProf.Tanand his introduction of bicyclic guanidine organocatalysts. These synthetically useful, as well as aesthetically pleasing structures show us that highly efficient catalysis may not be strictly contingent upon multifunctional activation, and steric effects aroundanisolatedguanidinemoietycanbesufficienttoachieveexcellentresults. While Prof. Tan’s work focuses on sterically rigid, mono-functional catalysts, a quiteantipodalapproach,usinghighlyflexibleguanidineswithmultiplefunctional groups attached, is shown to succeed just as well in the final chapter of Vol. I by Prof.Nagasawa. While the majority of Vol. I deals with guanidines as reagents and catalysts in the field of organic synthesis, the potential uses of guanidines certainly go far beyondthat.Inthesecondofthesetwovolumesafocusisplacedonthespecialized applications of guanidines. In the first chapter Prof. Concello´n and Prof. del Amo showustheirworksonstructurallysimpleguanidiniumsaltstoeffectivelymodify reactions catalyzed by the classic organocatalyst L-proline, demonstrating the designofelaboratenew catalyst structuresisnotnecessarilymandatory tobenefit from guanidine catalysis. Guanidine organocatalysis is also involved in an indus- triallyusefulfield,namelythenucleophilicactivationofCO asasustainableC1- 2 buildingblock.Prof.Pe´rezGonza´lezpresentsthis“green”useofguanidinecataly- sisinthefollowingchapter. Furtherhighlightingthepotentialusesofguanidinesoutsidetraditionalorganic synthesis Prof. Oppel presents guanidines as ligands for super-molecular metal- based frameworks, and the synthetic potential of such guanidinium-metal complexes is explored by Prof. Herres-Pawlis, exemplified in their use as highly active polymerization catalysts. Finally, at the end of this volume, Prof. Himmel takesusfarbeyondourfocusonsyntheticorganicchemistrywithhischapteronthe uniqueelectronicpropertiesofanionicguanidinatesandtheircomplexes. In summary, it was our goal to show that guanidines, guanidinium salts, and guanidinates offer a very diverse range of reactivity and thus great potential for a widevarietyofuses.Whilestillbeingregardedasaratherexoticclassofmolecules in the field of organocatalysis, especially in comparison to the prominent field of proline-induced imine/enamine activation or H-bond catalysis enabled by thioureas,the potentialofguanidinesasreagentsandcatalysts aswellasthedoor tonovelapplicationsiscertainlywideopen.Currently,inthemid-2010s,guanidine chemistryisahighlydynamicandrapidlydevelopingfieldofresearch,andwecan expect exciting new developments in the future. Guanidines as reagents and catalysts are here to stay and will continue to show up as versatile and valuable toolsbothinandbeyondorganicchemistry. Linz,Austria PhilippSelig November2016 Contents CooperativeGuanidinium/ProlineOrganocatalyticSystems. . . . . . . . . 1 CarmenConcello´nandVicentedelAmo GuanidinesasCatalystsforDirectandIndirectCO Capture 2 andActivation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 RafaelDiasdoEsp´ıritoSanto,RebecaMoniqueCapita˜o, andEduardoRene´ Pe´rezGonza´lez Triaminoguanidinium-BasedLigandsinSupramolecularChemistry. . . 75 CarolinavonEßen,ChristianR.Go¨b,andIrisM.Oppel GuanidineMetalComplexesforBioinorganicChemistry andPolymerisationCatalysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 JuliaStanek,ThomasRo¨sener,AngelaMetz,JohannesMannsperger, AlexanderHoffmann,andSonjaHerres-Pawlis Redox-ActiveGuanidinesandGuanidinate-SubstitutedDiboranes. . . . 165 Hans-Jo¨rgHimmel Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 vii TopHeterocyclChem(2017)51:1–26 DOI:10.1007/7081_2015_158 #SpringerInternationalPublishingSwitzerland2015 Publishedonline:2August2015 Cooperative Guanidinium/Proline Organocatalytic Systems CarmenConcell(cid:1)onandVicentedelAmo Abstract Organocatalysis is nowadays recognized as the third pillar of asym- metric synthesis, standing next to metal catalysis and enzymatic transformations. Proline has shown up as an ideal organocatalyst, being inexpensive and readily available.However,thisaminoacidhasalsomanifesteditslimitations.Compared to the chemical modification of proline, the approach through adding small hydrogen-bond-donating cocatalysts to interact with proline is particularly attrac- tive.Variousadditiveshavebeeninvestigatedtodate.Thischapterdisclosestheuse ofguanidiniumsaltsasadditivesforproline,investigatedinthecourseofproline- catalyzedaldolreactions. Keywords Guanidinium salts (cid:129) Organocatalysis (cid:129) Proline (cid:129) Supramolecular chemistry Contents 1 BriefIntroductiontoOrganocatalysisandItsLimitations.................................. 2 2 AdditivesUsedforProlineinOrganocatalyzedReactions................................. 3 3 GuanidiniumSaltsasAdditivesforProlineinOrganocatalyzedReactions............... 5 3.1 Cross-AldolReactionBetweenCyclicKetonesandAromaticAldehydes.......... 5 3.2 Cross-AldolReactionBetweenChloroacetoneandAromaticAldehydes........... 17 3.3 Cross-AldolReactionBetweenα-AzidoacetoneandAromaticAldehydes.......... 18 4 ConclusionsandOutlook.................................................................... 22 References........................................................................................ 24 C.Concell(cid:1)on(*)andV.delAmo(*) DepartamentodeQu´ımicaOrga´nicaeInorga´nica,UniversidaddeOviedo,C/Julia´nClaver´ıa8, 33006Oviedo,Spain e-mail:[email protected];[email protected] 2 C.Concell(cid:1)onandV.delAmo 1 BriefIntroductiontoOrganocatalysisandItsLimitations During the last decades, the demand of enantiomerically pure synthetic products has grown exponentially. This request has made asymmetric catalysis the most activeareaofresearchincontemporaryorganicchemistry.Illustratively,81ofthe 200blockbusterdrugsbyworldwidesalesareenantiopuresubstances. Traditionalasymmetriccatalysisreliesontheuseoftransitionmetalcomplexes (organometallic chemistry), or enzymes (biocatalysis). However, recently, a third type of catalysts has appeared: the organocatalysts, with its associated discipline asymmetric organocatalysis. This consists in the use of catalytic or substoichio- metric amounts of simple organic molecules to carry out highly enantioselective processes that take place in the absence of metallic elements. The use of organo- catalysts shows a number of advantages over the utilization of transition metal complexes: lower toxicity, low environmental impact, and absence of metallic elements which present potential contaminants in final products, many of them synthesizedforhumanoranimalintake.Similarly,organocatalystsdisplayadvan- tagesovertheuseofenzymes,whichcomeatasignificantlyhigherprizeandscarce availability. ProjectsdealingwithorganocatalysiscanbeframedinsideGreenChemistryand Sustainable Chemistry schemes. The concept of Sustainable Chemistry (in many occasionssynonymouswithGreenChemistry)referstoactionsaimingtoimprove theefficiencyintheuseofnaturalresources.Consequently,itcomprisesthedesign andimplementationofnewchemicalprocessesandtransformationsoperatingina moreefficient,safer,andmoreenvironmentallyfriendlyway.Havingtheintention of pursuing those goals, Sustainable Chemistryhas been formulated in12 univer- sally accepted principles, put forward by Anastas and Warner [1, 2]. Organo- catalytic processes satisfy several of them: high atomic efficiency, the use of reagentsoflowornontoxicity,littlegenerationofresidues,andtheuseofreagents incatalyticamounts.Moreover,theE-factorvaluesoftheseprocessesareremark- ablylow,whichisofinterestforindustry.TheE-factorquantifieshowtoxic/benign aparticularchemicalprocessisandisexpressedastheratioofgeneratedwasterper kilogramofproductproduced. Theuseofsmallorganicmoleculesascatalystsinchemicaltransformationscan be tracked back as far as the nineteenth century, to the pioneering works of Emil Knoevenagel[3–6].Itwasn’thoweveruntiltheyear2000,withthefindingsofList, Lerner, and Barbas on the potential of proline as a catalyst for the intermolecular aldolreaction[7]andthoseofMacMillan[8],whentheresearchinorganocatalysis commenced as a separate and well-defined field. Since then, the interest of the scientific community over this discipline has been phenomenal. Nowadays, the number of publications and literature reviews dealing with different aspects of asymmetric organocatalysis is extraordinarily large. It is far from the objectives of this monograph to cover the multiple and colored possibilities of this field. Nonetheless, the following selected citations (literature reviews) can summarize thestateoftheartofthediscipline[9–23].
The list of books you might like
