Chemistry of Thioamides PDF
Preview Chemistry of Thioamides
Toshiaki Murai Editor Chemistry of Thioamides Chemistry of Thioamides Toshiaki Murai Editor Chemistry of Thioamides 123 Editor ToshiakiMurai GifuUniversity Gifu, Japan ISBN978-981-13-7827-0 ISBN978-981-13-7828-7 (eBook) https://doi.org/10.1007/978-981-13-7828-7 ©SpringerNatureSingaporePteLtd.2019 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of 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 orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfrom therelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. The publisher, the authors and the editors are safe to assume that the advice and information in this 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, expressed or implied, with respect to the material contained hereinorforanyerrorsoromissionsthatmayhavebeenmade.Thepublisherremainsneutralwithregard tojurisdictionalclaimsinpublishedmapsandinstitutionalaffiliations. ThisSpringerimprintispublishedbytheregisteredcompanySpringerNatureSingaporePteLtd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore Preface I have been involved in the development of synthetic methods and new reactions using thioamides for about 20 years. On the basis of the teaching that it is not necessarytostayinabusyplacefromthebeginningwhenwestartnewresearchin the fields of synthetic chemistry, at first I hesitated to start that chemistry. Until then, I had studied compounds involving selenium and tellurium atoms, which are heavier elements of the sulfur atom in the Periodic Table. A limited number of researcherswereengagedinseleniumandtelluriumchemistry,andtherewasahigh possibilitythattheoriginalityofourownresearchwasguaranteed.Inthosestudies, one of graduate students in the laboratory discovered that new active chemical species were generated from selenoamides, which was a selenium analogue of amides, and the carbon–carbon bond-forming reaction using those was achieved. Ithoughtwecouldprovidenewsyntheticchemistrywiththosereactions.However, handling of organoselenium compounds are generally non-trivial. So I decided to startresearchbasedonthioamides,whoserichchemistryhasalreadybeenreported even at that time. Therefore, we had to be very careful to see if similar reactions werealreadyreportedornot.Fortunately,eveninthosesituations,weencountered several novel synthetic reactions. Afewyearsago,SpringerJapaninvitedmetopublishbooksonchemistry.Asa result ofsearchingliterature andon-linesearch, Inoticed that there wereno books that overlook the chemistry of thioamides even if the abundant achievement with thioamidesisknownoverhalfacentury.Fortunately,myproposalwiththechapters shown in the table of Contents was approved. I then asked an expert to write each chapter, and all the distinguished scientists accepted my invitation. Since then, as I received the manuscript from them, I strongly felt the responsibility to complete this book as soon as possible. At the sametime,Iamfullofgratitudeforallthescientists,whowroteeachchapterusing v vi Preface valuable time with expertise and enthusiasm. All the chapters provide abundant informationandcoverbroadaspectsofthioamides.Alternatively,youmaybeable to grasp the clues of new research by looking over a certain part. Gifu, Japan Toshiaki Murai March 2019 Contents 1 Thioamides: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Toshiaki Murai 2 Theoretical Aspects of Thioamides . . . . . . . . . . . . . . . . . . . . . . . . . . 7 José V. Cuevas, José García-Calvo, Víctor García-Calvo, Gabriel García-Herbosa and Tomás Torroba 3 Synthesis of Thioamides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Toshiaki Murai 4 Reaction of Thioamides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Toshiaki Murai 5 Asymmetric Synthesis Using Thioamides . . . . . . . . . . . . . . . . . . . . . 103 Naoya Kumagai and Masakatsu Shibasaki 6 Synthesis of Heterocycles from Thioamides . . . . . . . . . . . . . . . . . . . 127 Hong Yan and Hai-Chao Xu 7 Thioamide-Based Transition Metal Complexes. . . . . . . . . . . . . . . . . 157 Ken Okamoto, Junpei Kuwabara and Takaki Kanbara 8 Thioamide-Containing Peptides and Proteins . . . . . . . . . . . . . . . . . . 193 Taylor M. Barrett, Kristen E. Fiore, Chunxiao Liu and E. James Petersson vii Chapter 1 Thioamides: Overview ToshiakiMurai Abstract A range of sulfur isologues of carbonyl compounds are introduced. Amongthem,focushasbeenlaidonthesulfurisologueofamides,i.e.,thioamides. Researchfieldsonthioamideshavebeenspreadfromelucidationofthefundamental propertiestobiologicalapplications.Historicalbackgroundofthioamidesisshortly introduced.Recentresultsonthesestudiessuchasconformation,hydrogen-bonding interaction,self-disproportionationofenantiomers,andbiologicalaspectsarethen brieflyintroducedtoentereachchapterofthisbook,wherethedetailsareshown. · · · Keywords Thioamides Conformation Hydrogen-bonding · · Self-disproportionation Metalcomplexes Biologicalactivity The replacement of the oxygen atom in amides with the sulfur atom gives rise to the formation of thioamides. Amides have been recognized as the least reactive carboxylic acid derivatives. In that sense, similar tendency may be seen when you compare the reactivity of thioaldehydes 1 (thials), thioketones 2 (thiones) [1], and thioicacidO-esters3(Fig.1.1).Theisolationofthioaldehydes1andthioketones2is nontrivialunlessbulkysubstituentsareintroducedaroundthiocarbonylgroups[2]. Incontrast,sulfurisologuesofamidessuchasthioformamide4(methanethioamide), thioacetamide5(ethanethioamide),andbenzothioamide6(benzenecarbothioamide) haveappearedintheliteratureinthelatenineteenthcenturies[3–6],andtheirsynthe- sisandpropertieshavebeencontinuouslystudied,althoughtheseprimarythioamides can decompose via the elimination of hydrogen sulfide to give mixtures including nitriles. Studiesintheearlytwentiethcenturymayhavelaidonaviewpointofhowthe propertiesofthecompoundschangewhenoneoftheelementsinmoleculesbelong- ingtothesecondrowoftheperiodictableisreplacedbytheelementinthethirdand subsequent periods. Hereafter, the thioamide moiety (C=S–N) was found to show unique properties, and compounds having this unit were found in nature, so that B T.Murai( ) DepartmentofChemistryandBiomolecularScience,FacultyofEngineering,GifuUniversity, Yanagido,Gifu501-1193,Japan e-mail:[email protected] ©SpringerNatureSingaporePteLtd.2019 1 T.Murai(ed.),ChemistryofThioamides, https://doi.org/10.1007/978-981-13-7828-7_1 2 T.Murai Fig.1.1 Someof S S S thiocarbonylcompounds R H R1 R2 R1 OR2 1 2 3 thioaldehydes thioketones thioic acid O-esters S S S H 4 NH2 H3C 5 NH2 Ph 6 NH2 thioformamides thioacetamides benzothioamide Fig.1.2 Resonance S S S structuresofthioamides H + H + H R N R N R N 8 9 10 H H H researchfieldshaveextensivelyexpandedfromfundamentalchemistrytobiochem- istryandmaterialchemistry. Similarly to amides, resonance structures of thioamides 8 can be depicted as 9 and10(Fig.1.2).However,thecontributionoftheresonancestructure9ismarkedly smallerthanthatinthecorrespondingamidesmainlybecauseofthesimilarityofthe electronegativityofcarbonandsulfuratoms[7].Asaresult,thioamidesarelesspolar thanthecorrespondingamides,andthepurificationofthioamidesiseasierthanthe amideshavingidenticalcarbonskeletons.Incontrasttoamides,thechargetransfer fromthenitrogenatomtotheC=Sbondsisgreater,andtherotationalbarrierofC=N bondislarger[8]. Hydrogen-bonding including S–H bonds and conformations around C=S–NH bondsareofinterestinthefieldsofpurechemistryaswellasthiopeptidechemistry. Generally, the C=S–NH bonds are weaker acceptor of the hydrogen bonds, and the NH proton is more acidic and can work as a hydrogen bond donor [9, 10]. To gain insights of the hydrogen-bonded systems, thioamides such as 11 and 12 (Fig.1.3)areprepared,andtheirstructuresandhydrogen-bondinginteraction,and π-π stacking are elucidated. The relationship of the substituents on the aromatic rings and conformation around C=S–NH bonds is extensively studied with N-aryl arylthioamides 13 (Fig. 1.4) [11]. Z-Conformation is usually preferable, and the detail of the isomerization is revealed by variable-temperature NMR and NOESY experimentsandDFTcalculations. Self-disproportionationofenantiomers(SDE)isobservedduringthepurification of the optically active compounds with some enantiomeric excess (ee) [12]. The ee of the purified products is not identical in some fractions collected during the achiralchromatographicseparation.Thephenomenaarerelatedtothestrengthofthe hydrogen-bondinginteractions.Toshowthisphenomenonofthioamides,optically active thioamide 14 is prepared (Fig. 1.5). Its SDE is observed, although SDE is substantiallylowerthanthatofthecorrespondingamide.Thesoftnessofthesulfur atomenablesthioamidestobehaveasligandsmainlytosoftmetals. 1 Thioamides:Overview 3 Fig.1.3 benzene-1,3,5- R tricarbothioamides R S HN S HN R R N S N S H H S NH S NH R R 12 11 R = R = Fig.1.4 N-Aryl R3 arylthioamides R1 S N R4 H 13 R2 Fig.1.5 ChiralN-1- S Me phenylethyl thioacetamide N * H 14 * chiral center E S S Br N NH 1156 EE == OS Et NH2 n-Pr NH2 N 17 N 18 Br OH O S S S S S S N N N N N N H H H H H H HO 19 OH Fig.1.6 Someofbiologicallyrelevantthioamides Thereplacementoftheoxygenatomtothesulfuratomalsoaffectsthephysio- logicalactivityofthemolecules.Insomecases,theactivitymaydecrease,butsome oftheresultshaveshownthatthereplacementenhancedtheactivity[13].Forexam- ple, the oxygen atom of longamide B (15) is replaced with a sulfur atom to form thioamide16(Fig.1.6)[14].Thecompound16showshigherinhibitoryactivitythan 15asanindoleamine2,3-dioxygenase1inhibitor.
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