收稿:2007年7月,收修改稿:2007年10月 3国家自然科学基金项目(No.20602012,2053310)和上海市青年科技启明星计划(No.07QA14017)资助33通讯联系人 e2mail:hhwu@手性咪唑啉酮类有机催化剂催化的不对称反应3
姚成福 孙彩霞 闫少宇 吴海虹33(上海华东师范大学化学系绿色化学与化工过程绿色化重点实验室 上海200062)
摘 要 近年来,不对称有机催化过程日趋成熟,用于越来越多的实际应用。相对于金属催化过程有机胺催化剂具有许多潜在的优势:相对比较稳定,价格较低,容易得到,没有金属泄露到环境或产品中的风险以及对操作环境要求不高等,有机胺催化已被证明是实现不对称转化的有效手段。手性咪唑啉酮催化剂是有机胺催化剂中重要的一种类型。本文总结了手性咪唑啉酮催化剂在Diels2Alder反应、1,32偶极环加成、Michael反应、Friedel2Crafts烷基化等不对称催化反应中的应用研究进展,并对未来手性咪唑啉酮在工业中的应用作了展望。关键词 有机催化 不对称反应 手性咪唑啉酮 亚胺离子 烯胺 中间体中图分类号:O621125;O643136 文献标识码:A 文章编号:10052281X(2008)0620887212
ChiralImidazolidinones2CatalyzedAsymmetricReactions
YaoChengfu SunCaixia YanShaoyu WuHaihong33(ShanghaiKeyLaboratoryofGreenChemistryandChemicalProcesses,ChemistryDepartmentofEastChinaNormalUniversity,Shanghai200062,China)
Abstract Enantioselectiveorganocatalyticprocesseshavedevelopedmaturelyinrecentyearswithanimpressivenumberofapplicationsnowavailable.Aminocatalysishasproventobeapowerfulprocedurefortheenantioselectivetransformationsowingtotheirpotentialadvantagesovermetal2catalyzedprocesses:usuallymorestable,lessexpensive,readilyavailable,noriskofmetalleakageintoenvironmentortheproduct,andcanbeappliedinlessdemandingreactionconditions.Chiralimidazolidinonesisanimportantsortofaminocatalysts.Thepapersummarizestheapplicationsandadvancesofchiralimidazolidinonesinasymmetriccatalyticreactions,suchasDiels2Alderreaction,1,32dipolarcycloaddition,Michaelreaction,Friedel2Craftsalkylation.Moreover,thefutureapplicationsofchiralimidazolidinonesintheindustrymanufacturesarealsoprospected.Keywords organocatalysis;asymmetricreactions;chiralimidazolidinones;iminiumions;
N‑HeterocyclicCarbene-Palladium(II)-1-MethylimidazoleComplex-CatalyzedDirectC−HBondArylationof(Benz)imidazoleswithArylChloridesZheng-SongGu,†Wen-XinChen,†andLi-XiongShao*,†,‡†CollegeofChemistryandMaterialsEngineering,WenzhouUniversity,ChashanUniversityTown,Wenzhou,ZhejiangProvince325035,People’sRepublicofChina‡CollegeofChemistryandLifeSciences,ZhejiangNormalUniversity,Jinhua,ZhejiangProvince321004,People’sRepublicofChina*SSupportingInformationABSTRACT:(Benz)imidazolescanbeefficientlyfunctionalizedby(hetero)arylchloridesviadirectC−Hbondarylationinthepresenceofawell-definedNHC-Pd(II)-Imcomplex.Undertheoptimalconditions,variousactivated,unactivated,anddeactivated(hetero)arylchloridesweresuccessfullyappliedasthearylatingreagentstoachievethe2-(hetero)aryl(benz)imidazolesinacceptabletohighyields,givingafacileandalternativemethod-ologyforthedirectC−Hbondarylationof(benz)imidazoles.■INTRODUCTIONC2-arylated(benz)imidazolesarefrequentlyfoundinvariouspharmaceuticals,biologicallyactivecompoundsandmaterials.1Recently,thetransitionmetal-catalyzeddirectC−Hbondarylationof(benz)imidazoleshasbeennoticedasapotentiallymoreefficientandconvenientalternativeforthestraightfor-wardsynthesisofsuchcompounds.2However,duringthepastyears,thescopeofthearylatingreagentsislimitedtothemoreactivearyliodidesandbromides.3Tothebestofourknowledge,onlyveryfewexamplesonthepalladium-catalyzeddirectC2-arylationof(benz)imidazolesusingarylchloridesinthepresenceofphosphineligandswerereportedtodate,despitetheirlowercostandmoreeasyavailability.4Therefore,despitethatsomeprogresshasbeenmadeinthedirectC2-arylationof(benz)imidazoles,theresearchforefficientmethodsusingthemoreapplicable,whilelessactive,arylchloridesasthearylatingreagentsisstillingreatdemand.5Previously,wehavereportedthatawell-definedN-heterocycliccarbene-Pd(II)-1-methylimidazole[NHC-Pd(II)-Im]complex1caneasilyactivatearylchloridesintraditionalC−Ccouplingssuchasα-arylationofcarbonylcompounds,6Suzuki−Miyauracoupling,7Mizoroki−Heckreaction,8Hiyamareaction9andC−Ncoupling.10Furthermore,inaveryrecentcommunication,wefoundthatNHC-Pd(II)-Imcomplex1canalsoefficientlycatalyzethedirectC−Hbondarylationof(benzo)oxazolesusingarylchloridesasthearylatingreagents.11TheseresultsthuspromptedustofurtherinvestigateitsapplicationinactivatingarylchloridestowardthedirectC2-arylationof(benz)imidazoles.Herein,wereporttheseresultsindetail.■RESULTSANDDISCUSSIONInitially,1-methylbenzimidazole2a(0.49mmol)waschosenasthemodelsubstrateforthereactionwithchlorobenzene3a(2.0equiv)inthepresenceofNHC-Pd(II)-Imcomplex1(2.0mol%)undervariousconditions.Forexample,inthefirstround,toluene/H2O(2.0mL/0.5equiv)waschosenasthesolventstoevaluatetheeffectofbases.ThebestresultwasachievedusingKOtBuasthebasetogivethedesiredproduct4ain89%yield(Table1,entry6),whileinthepresenceofotherbasessuchasK2CO3,KOH,K3PO4·3H2O,LiOtBuandNaOtBu,almostnoproductcouldbedetected(Table1,entries1−5).Thereplacementofsolventsfromtoluene/H2OtoTHF/H2Oanddioxane/H2Oresultedinproduct4aonlybeingisolatedin48and40%yields,respectively(Table1,entries7and8).Inaddition,inthepresenceofothersolventssuchasDMSO/H2O,DMF/H2O,CH3CN/H2OandDME/H2O,nodesiredproductcouldbedetected(Table1,entries9−12).Furthermore,aftercarefulinvestigations,itwasfoundthattheamountofH2Odramaticallyaffectedthereaction.Thatis,theintroductionof0.5equivofH2Owasfoundtobenecessaryforsuchtransformation.Forinstance,only18%yieldofproduct4awasobtainedwhendrytoluenewasusedasthesolvent(Table1,entry13).When1.0equivofH2Owasadded,asignificantlyhigheryield(84%)wasachieved(Table1,entry14).However,whentheamountofH2Owasincreasedto3.0equiv,theyieldof4adrasticallydecreasedto5%(Table1,entry15).TheseresultsthusencouragedustofurtherinvestigatetheeffectofH2O.ItisknownthatKOtBuwillbepartiallyhydrolyzedtoKOHandHOtBuundertheabovereactionconditions.Therefore,threemorecontrolexperimentswerecarriedout:(1)thecombinationofKOtBu(1.5equiv),KOH(0.5equiv)andHOtBu(0.5equiv)wasintroducedinsteadofKOtBu(2.0Received:May9,2014Published:May28,/joc
NewsialylLewisxmimiccontainingana-substituted
b3-aminoacidspacer
SilvanaPedatella,a,*MauroDeNisco,aBeatErnst,bAnnalisaGuaragna,a
BeatriceWagner,bRobertJ.WoodscandGiovanniPalumboa
aDipartimentodiChimicaOrganicaeBiochimica,Universita`diNapoliFedericoII,ViaCynthia,4I-80126Napoli,ItalybInstituteofMolecularPharmacy,Pharmacenter,UniversityofBasel,Klingelberstrasse,50CH-4056Basel,SwitzerlandcComplexCarbohydrateResearchCenter,UniversityofGeorgia,315RiverbendRoad,Athens,GA30602,USA
Received11June2007;receivedinrevisedform20August2007;accepted2October2007Availableonline7October2007
Abstract—AhighlyconvergentandefficientsynthesisofanewsialylLewisx(sLex)mimic,whichwaspredictedbycomputationalstudiestofulfilthespacialrequirementsforaselectinantagonist,hasbeendeveloped.Withab2,3-aminoacidresidueL-galactose(bioisostereoftheL-fucosemoietypresentinthenaturalsLex)andsuccinatearelinked,leadingtoamimicofsLexthatcontainsalltherequiredpharmacophores,namelythe3-and4-hydroxygroupofL-fucose,the4-and6-hydroxygroupofD-galactoseandthecarboxylicacidofN-acetylneuraminicacid.ThekeystepofthesynthesisinvolvesatandemreactionconsistingofaN-deprotectionandasuitableO!Nintramolecularacylmigrationreactionwhichispromotedbyceriumammoniumnitrate(CAN).Finally,thenewsialylLewisxmimicwasbiologicallyevaluatedinacompetitivebindingassay.Ó2007ElsevierLtd.Allrightsreserved.
DOI:10.1002/anie.201210238
ComparisonofOxidativeAromaticCouplingandthe
SchollReaction
MarekGrzybowski,KamilSkonieczny,HolgerButenschçn,*and
DanielT.Gryko*Angewandte
ChemieKeywords:
arenecoupling·biaryls·Lewisacids·
oxidativecoupling·SchollreactionDedicatedtoProf.AlexandruBalabanonthe
occasionofhis80thbirthday.Angewandte
ReviewsH.Butenschçn,D.T.Grykoetal.
2013Wiley-VCHVerlagGmbH&Co.KGaA,WeinheimAngew.Chem.Int.Ed.2013,52,9900–99301.Introduction
Thefirstexampleofanoxidativedimerizationofaromatic
compoundswaspublishedin1871,[1]and39yearslater
RolandSchollreportedthatasimilareffectcanbeachieved
byheatingcertainaromaticcompoundswithAlCl3.[2]For
manyyears,thesetworeactionsweredistinguishable,and
whenBalabanandNenitzescupublishedtheirfundamental
reviewontheSchollreaction,therewasstillacleardemar-
cationbetweenthem.[3]Nowadays,however,thereisamix-up
