- Iodine catalysed intramolecular C(sp3)-H functionalization: synthesis of 2,5-disubstituted oxazoles from N-arylethylamides
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Iodine catalyzed synthesis of 2,5-disubstituted oxazoles from N-arylethylamides through intramolecular C(sp3)-H functionalization under metal-free conditions is described. The method is tolerable to a wide range of substrates having a variety of functional groups with moderate to good yields of the products.
- Samanta, Supravat,Donthiri, Ramachandra Reddy,Dinda, Milan,Adimurthy, Subbarayappa
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p. 66718 - 66722
(2015/08/24)
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- Metal-free dual sp3 C-H functionalization: I2- promoted domino oxidative cyclization to construct 2,5-disubstituted oxazoles
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An I2-promoted sp3 C-H functionalization has been developed for the synthesis of 2,5-disubstituted oxazoles from easily available methyl ketones and benzylamines without any metal and peroxide catalyst. This domino oxidative cyclization process involves the cleavage of C-H bond and the formation of C-N, C-O bonds.
- Gao, Qing-He,Fei, Zhuan,Zhu, Yan-Ping,Lian, Mi,Jia, Feng-Cheng,Liu, Mei-Cai,She, Neng-Fang,Wu, An-Xin
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- Photophysics of a series of efficient fluorescent pH probes for dual-emission-wavelength measurements in aqueous solutions
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This paper evaluates the 5-aryl-2-pyridyloxazole backbone to engineer donor-acceptor fluorescent pH probes after one- or two-photon absorption. Parent fluorophores, as well as derivatives that can be used to label biomolecules, can be easily obtained in good yields. These molecules exhibit a large one-photon absorption in the near-UV range, and a strong fluorescence emission that covers the whole visible domain. The 5-aryl-2-pyridyloxazole derivatives also possess significant cross sections for two-photon absorption. Upon pyridine protonation, large shifts were observed in the absorption spectra after one- and two-photon excitation, as well as in the emission spectra. This feature was used to measure the pKa of the investigated compounds that range between 2 and 8. In most of the investigated derivatives, the pKa increased upon light excitation and protonation exchanges took place during the lifetime of the excited state, as shown by phase-modulation fluorometry analysis. Several 5-aryl-2-pyridyloxazole derivatives are suggested as efficient probes to reliably measure the pH of aqueous solutions by means of ratiometric methods that are dependent on fluorescence emission.
- Charier, Sandrine,Ruel, Odile,Baudin, Jean-Bernard,Alcor, Damien,Allemand, Jean-Francois,Meglio, Adrien,Jullien, Ludovic,Valeur, Bernard
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p. 1097 - 1113
(2007/10/03)
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- Combinatorial discovery of novel fluorescent dyes based on Dapoxyl
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We have developed a combinatorial method for the fast and effective synthesis of a library based on a known fluorescent dye, Dapoxyl using parallel solution-phase chemistry. By screening the 140 new compounds using fluorescence-based assays, we identified three new fluorescent dyes with novel properties.
- Zhu, Qing,Yoon, Hai-Shin,Parikh, Puja B.,Chang, Young-Tae,Yao, Shao Q.
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p. 5083 - 5086
(2007/10/03)
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- SPECTRAL-LUMINISCENCE PROPERTIES AND BASICITIES OF 2-(4-PYRIDYL)-5-(4-R-PHENYL)OXAZOLES
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The spectral-luminiscence and acid-base properties of 2-(4-pyridyl)-5-(4-R-phenyl)oxazoles were studied.Significant ?-electron conjugation between the individual fragments exists in the molecules of these compounds in solutions at room temperature.Bathochromic and bathofluoric effects, which are particularly appreciable for electron-donor substituents, are observed when substituents R are introducted into the 5-phenyl ring.Ethanol solutions of the investigated compounds have high fluorescence quantum yields which, for some of them, are close to unity.Electron-donor substituents R increase the basicity of the pyridine nitrogen atom.
- Afanasiadi, L. Sh.,Tur, I. N.,Kurapov, P. B.
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p. 397 - 400
(2007/10/02)
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