- Electrochemical oxidation-induced benzyl C–H carbonylation for the synthesis of aromatic α-diketones
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Electrochemical oxidation-induced direct carbonylation of benzyl C–H bond for the synthesis of aromatic α-diketones is described. In this process, tetrabutylammonium iodide (nBu4NI) not only acts as an electrolyte, but its iodine anion is oxidized to an iodine radical at the anode, acting as a hydrogen atom transfer agent. The iodine radical extracts the benzyl hydrogen atom and causes the carbonylation of the benzyl position, where O2 in the air is used as an oxygen source.
- Tan, Yu-Fang,Chen, Yuan,Li, Rui-Xue,Guan, Zhi,He, Yan-Hong
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supporting information
(2021/12/21)
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- V2O5@TiO2 Catalyzed Green and Selective Oxidation of Alcohols, Alkylbenzenes and Styrenes to Carbonyls
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The versatile application of different functional groups such as alcohols (1° and 2°), alkyl arenes, and (aryl)olefins to construct carbon-oxygen bond via oxidation is an area of intense research. Here, we report a reusable heterogeneous V2O5@TiO2 catalyzed selective oxidation of various functionalities utilizing different mild and eco-compatible oxidants under greener reaction conditions. The method was successfully applied for the alcohol oxidation, oxidative scission of styrenes, and benzylic C?H oxidation to their corresponding aldehydes and ketones. The utilization of mild and eco-friendly oxidizing reagents such as K2S2O8, H2O2 (30 % aq.), TBHP (70 % aq.), broad substrate scope, gram-scale synthesis, and catalyst recyclability are notable features of the developed protocol.
- Upadhyay, Rahul,Kumar, Shashi,Maurya, Sushil K.
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p. 3594 - 3600
(2021/07/02)
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- Amphiphilic ligands for Cu-catalyzed aerobic oxidation to synthesize 9-fluorenones in water
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A series of amphiphilic PEG-functionalized nitrogen ligands were developed for the highly efficient copper-catalyzed aerobic oxidation of 9-fluorenes, with molecular oxygen as the sole oxidant in neat water. A broad range of functional groups are well tolerated and thus offer the opportunity for further functionalization.
- Li, Longjia,Liu, Zibo,Tang, Shanyu,Li, Jiao,Ren, Xuanhe,Yang, Guanyu,Li, Heng,Yuan, Bingxin
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- Ionic liquid [bmim]Br assisted chemoselective benzylic [Formula presented] oxidations using tert-butyl hydroperoxide
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A mild and efficient, ionic-liquid-assisted green protocol for the chemoselective oxygenation of benzylic C-H bonds to corresponding ketones using ionic liquid [bmim]Br with tert-butyl hydroperoxide has been developed. The method reported in this paper has the advantages of [bmim]Br acting as recyclable solvent and reagent. The usage of additives such as acids or bases and metal salts is not required. The developed strategy is further extended to oxidation of secondary alcohols to respective ketones under similar optimized reaction conditions.
- Naidu, Shivaji,Reddy, Sabbasani Rajasekhara
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p. 441 - 445
(2016/07/27)
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- Synthesis and Photoisomerization of Substituted Dibenzofulvene Molecular Rotors
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The synthesis, spectral and structural characterization, and photoisomerization of a family of 2-substituted dibenzofulvene molecular actuators based on (2,2,2-triphenylethylidene)fluorene (TEF) are reported. The 2-substituted species investigated are nitro (NTEF), cyano (CTEF), and iodo (ITEF). X-ray structures of these three compounds and three intermediates were determined to assign alkene configuration and investigate the effects of the 2-substituents on steric gearing. The addition–elimination reaction of Z-9 with trityl anion to form Z-10 proceeded with complete retention of configuration. Rates of photoisomerization were measured at irradiation wavelengths between 266–355 nm in acetonitrile/dioxane solutions at room temperature. Photoisomerization quantum yields (φ) were calculated by means of a mathematical model that accounts for a certain degree of photodecomposition in the cases of CTEF and ITEF. Quantum yields vary significantly with substituent, having maximum values of φ=0.26 for NTEF, 0.39 for CTEF, and 0.50 for ITEF. NTEF is photochemically robust and has a large quantum yield for photoisomerization in the near-UV, making it a particularly promising drive rotor moiety for light-powered molecular devices.
- Everhart, Stephanie C.,Jayasundara, Udaya K.,Kim, HyunJong,Procúpez-Schtirbu, Rolando,Stanbery, Wayne A.,Mishler, Clay H.,Frost, Brian J.,Cline, Joseph I.,Bell, Thomas W.
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p. 11291 - 11302
(2016/08/03)
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- On the Transmission of Substituent Effects in Fluorenes and Fluorenones
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A series of 2- and 2,7-substituted fluorenes (1) and fluorenones (2) were prepared either by electrophilic substitution (1c-f, h-j; 2c, d, j), reduction (1, 2k, l) or nucleophilic exchange (1g, m, n; 2m) via respective diazonium compounds as well as by oxydation (2e-h, n) of the hydrocarbons (1).The carbon-13 n.m.r. spectra for the fluorene (1a-n) and fluorenone (2a-n) derivatives was analyzed using a dual substituent parameter (DSP) equation.The substituent chemical shifts (SCS) of the carbon atoms 4a, 4b, 7 and 4a, 4b, 7, 9 of eleven fluorenes and nine fluorenones,respectively, correlate with the F, R substituent constants and with ?I, ?R0 ones in a satisfactory manner.The comparison indicates that the correlation with the F, R constants yields always a higher resonance contribution than the calculation with ?I, ?R0 constants.The DSP analysis reveals that transmission of the substituent effect to the substituted ring is primarily resonance controlled while the transmission to the second ring involves a ?-bond polarization mechanism.For C-4b in the unsubstituted ring a reversed substituent effect was found.In contrast to fluorenes in fluorenones the transmission of the substituent effect involves the carbon atom 9.
- Hauser, A.,Thurner, J.-U.,Hinzmann, B.
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p. 367 - 378
(2007/10/02)
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