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1、J.Org.Chem.2000,65,8041-80508041SupramolecularPhotochirogenesis.2.EnantiodifferentiatingPhotoisomerizationofCycloocteneIncludedandSensitizedby6-O-ModifiedCyclodextrins^YoshihisaInoue,*,²,³TakehikoWada,²NorimitsuSugahara,²KeikoYamamoto,²KoichiKimura,²Lin-HuiTong
2、,§Xing-MingGao,§Zhi-JieHou,§andYuLiu
3、DepartmentofMolecularChemistry,OsakaUniversity,2-1Yamada-oka,Suita565-0871,Japan,InouePhotochirogenesisProject,ERATO,JST,4-6-3Kamishinden,Toyonaka565-0085,Japan,LanzhouInstituteofChemicalPhysics,AcademiaSinica,Lanzhou730000,
4、China,andDepartmentofChemistry,NankaiUniversity,Tianjin300071,Chinainoue@chem.eng.osaka-u.ac.jpReceivedAugust18,2000Supramolecularenantiodifferentiatingphotoisomerizationof(Z)-cyclooctene(1Z)tothechiral(E)-isomer(1E)viainclusionandsensitizationbymodifiedR-,â-,a
5、nd/orç-cyclodextrinderivatives,possessingbenzoate(2a,3a,4a),isomericphthalates(3b-d),andtetheredbenzamide(3e)chromophores,hasbeeninvestigatedinaqueousmethanolsolutionsatvaryingtemperatures.Thephotostationary-state1E/1Zratiosobtaineduponsensitizationwith2-4in1:1
6、water-methanolreached0.4-0.8,whicharehigherthanthevalueofca.0.25reportedforsensitizationsbyconventionalalkylbenzoatesinhydrocarbonsolvents,althoughtheratiowasreducedto0.2-0.4inwaterormethanol.Thesensitizationsof1ZbyR-andç-cyclodextrinbenzoates(2a,4a)withsize-mi
7、smatchedcavitiesgave1Eofpoorenantiomericexcesses(ee's)smallerthan3and5%,respectively.Incontrast,â-cyclodextrinderivatives(3a-e)affordedmuchhigheree'sofupto24%,dependingonthesolventcomposition.Thus,themodificationofcyclodextrinwithasensitizinggroupsuccessfullyen
8、hancedtheproductthroughtheexcited-statesupramolecularinteractionwithinthecavity.Interestingly,theproductee'sobtainedwithbenzoate3aandmethylphthalate3barenotasimplefunctionofeithertemperatureorsolvent,butarenicelycorrelatedwiththehostoccupancyorthepercentageofoc
9、cupiedhost.Thismeansthattheentropyfactorplaysaninsignificantroleinthissupramolecularphotochirogenesissystem,whichisinsharpcontrasttothedecisiveroleofentropyintheconventional
