188宝金博页面版

Synthesis of 2,5-diaryl-4-halo-1,2,3-triazoles and comparative studyof their f l uorescent propertiesVladimir A. Motornova , b , Andrey A. Tabolin a , * , Roman A. Novikov a , c , Nikolay E. Shepel d ,Valentine G. Nenajdenkoe , Sema L. Ioffe aa N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky prosp. 47, Moscow, 119991, Russiab Higher Chemical College, D. I. Mendeleev University of Chemical Technology of Russia, Miusskaya sq. 9, Moscow, 125047, Russiac V. A. Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str. 32, Moscow, 119991, Russiad A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str. 28, Moscow, 119991, Russiae Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskiye Gory 1, Moscow, 119991, Russiaa r t i c l e i n f oArticle history:Received 26 April 2018Received in revised form21 May 2018Accepted 24 May 2018Available online 26 May 2018Keywords:1,2,3-TriazolesChan-Lam couplingOrganof l uorine compoundsNear UV luminescenceCopper catalysisa b s t r a c tA convenient method for arylation of mono- and disubstituted 1,2,3-triazoles by copper-catalyzed Chan-Lam coupling was developed. The method is applicable for the regioselective synthesis of f l uorescent 4-halogen-substituted (Hal ¼ F, Cl, Br) 2,5-diaryl-1,2,3-triazoles in high yields. Comparative study of theirf l uorescent properties revealed that 4-f l uorosubstituted triazoles possess the highest quantum yield (upto 0.69) among halogenated triazoles possessing Cl and Br in the position 4.© 2018 Elsevier Ltd. All rights reserved.1. IntroductionAt the present time f l uorescent compounds gain considerableattention of chemists. The design of new f l uorophores is anattractive f i eld due to possible application in molecular imaging,preparationof OLED and chemosensors. 1 These various uses requirecompounds with ranging characteristics, such as absorbance andemission maxima, quantum yield, f l uorescence intensity. Recently,N-2-aryl substituted 1,2,3-triazoles were demonstrated as a newclass of the blue-light emitting f l uorophores. 2 Thus, importance oftriazole scaffold in the medicinal and material chemistry areas 3,4makes them promising substrates for novel f l uorophore develop-ment. We were particularly interested in f l uorine-containing tri-azoles and their properties. 5 Indeed, incorporation of f l uorine atomis known to affect both physical and chemical properties of mole-cules, such as stability, polarity or lipophilicity. 6 There are examplesof increasing in quantum yields upon f l uorine introduction. 7Importantly, presence of f l uorine may also increasephotochemical stability of target molecules. 7a,8 Despite the inf l u-ence of various functional groups (alkyl, amino) on the opticalcharacteristics of 1,2,3-triazoles is rather well-studied, 2,9 the effectof halogen substituents is almost not investigated (Scheme 1). Inthe present paper we report a method for the synthesis of 2,5-diaryl-4-f l uoro-1,2,3-triazoles and comparative study of theirf l uorescent properties.2. Results and discussionFor the synthesis of target arylated triazoles copper-catalyzedreaction with boronic acids (Chan-Lam coupling) was chosen. 10,11Nowadays, this method is widely used for the arylation ofdifferent N-nucleophiles, such as amines, anilines, as well as im-idazoles, pyrazoles and pyrroles. 12 However, Chan-Lam coupling forregioselective arylation of p -def i cient heterocycles such as 1,2,3-triazoles is studied only for 4,5-disubstituted examples and re-mains being a challenging task. 13 We initiated our studies witharylation of 4-f l uoro-1,2,3-NH-triazole 1a by benzeneboronic acidin the common Chan-Lam coupling conditions using 1 equiv.Cu(OAc) 2 $H 2 O as a copper source under air (Table 1). 14 Screening of* Corresponding author.E-mail address: tabolin87@mail.ru (A.A. Tabolin).Contents lists available at ScienceDirectTetrahedronjournal homepage: www.elsevier.com/locate/tethttps://doi.org/10.1016/j.tet.2018.05.0710040-4020/© 2018 Elsevier Ltd. All rights reserved.Tetrahedron 74 (2018) 3897e3903