- Oxidative Cleavage of Indoles Mediated by Urea Hydrogen Peroxide or H2O2 in Polar Solvents
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The oxidative cleavage of indoles (Witkop oxidation) involving the use of H2O2 or urea hydrogen peroxide in combination with a polar solvent has been described. Among these solvents, 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) stands out as the one affording the corresponding 2-ketoacetanilides generally in higher yields The protocol described has also enabled the oxidation of different pyrroles and furans derivatives. Furthermore, the procedure was implemented in a larger-scale and HFIP was distilled from the reaction mixture and reused (up to 4 cycles) without a significant detriment in the reaction outcome, which remarks its sustainability and applicability. (Figure presented.).
- Llopis, Natalia,Gisbert, Patricia,Baeza, Alejandro
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supporting information
p. 3245 - 3249
(2021/06/08)
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- Reduced graphene oxide grafted by the polymer of polybromopyrroles for nanocomposites with superior performance for supercapacitors
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An integrated structure has been designed by grafting the polymer of polybromopyrroles (PPBP) onto reduced graphene oxide (RGO) to produce RGO/PPBP nanocomposites with superior electrochemical performance for supercapacitors. The RGO/PPBP nanocomposites are featured with a high nitrogen content (>9 at%), enhanced degree of graphitization, improved specific surface area, abundant micropores, and a tunable hierarchical structure on the basis of sample characterization by XRD, Raman, FT-IR, XPS, SEM, high-resolution TEM, BET, and scanning probe microscopy (SPM) techniques. The grafting of PPBP onto RGO not only suppresses agglomeration and restacking of RGO but also tailors the growth of PPBP on RGO, producing a developed hierarchical structure beneficial for mass/charge transfer. The synergistic effect between RGO and PPBP ensures superior electrochemical performance of RGO/PPBP. In a three-electrode mode, the typical RGO/PPBP electrode presents a galvanostatic capacitance (Cg) of 256 F g-1 at a current density of 10 A g-1, with a capacitance retention of 99.2% after 10000 cycles in 1 mol L-1 H2SO4. More significantly, the typical RGO/PPBP&3Verbar;RGO/PPBP supercapacitor cell exhibits a high Ccell value of 68 F g-1 at 5 A g-1, with a capacitance retention of 91.9% after 10000 cycles. Also, relatively high energy density values of 13.6, 9.4, and 6.7 W h kg-1 with the corresponding power density of 0.5, 2.5, and 10 kW kg-1 are achieved, enabling the tested cell to stay at the high level for carbon-based supercapacitors with an aqueous electrolyte.
- Wang, Shouzhi,Gai, Ligang,Jiang, Haihui,Guo, Zhenzhen,Bai, Nana,Zhou, Jianhua
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p. 21257 - 21268
(2015/11/09)
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- Controlled oxidation of pyrroles: Synthesis of highly functionalized γ-lactams
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The oxidation of pyrroles usually leads to uncontrolled polymerization and decomposition. To overcome this problem, the controlled oxidation of substituted pyrroles with Dess-Martin periodinane is reported. This strategy yields a range of 5-aroyloxypyrrol
- Howard, James K.,Hyland, Christopher J. T.,Just, Jeremy,Smith, Jason A.
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supporting information
p. 1714 - 1717
(2013/06/27)
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- Synthesis of Five-membered 2-Heteroaryl 2-Heteroaromatic Carboxylates and Attempted Cyclization to Bisheteroaryl[2,3-b:3′2′-d]pyran-2-one
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2-Heteroaryl 2-heteroaromatic carboxylates were prepared by reactions of 2-heteroaromatic carbonyl chlorides and 2(5H)-furanone, 2(5H)-thiophenone, and 1-methyl-2(5H)-pyrrolone in triethylamine. The 1H nmr spectra of the esters showed that the electronic effect of both heteroaromatic rings did not cause any sizable shift from each other except for 1-methyl-2-pyrrolyl 1-methyl-2-pyrrolecarboxylate (5c). Attempts to cyclize the esters to heteroaryl-fused pyran-2-ones were unsuccessful. The results may be explained by the most stable conformation of the esters in which two heteroatoms are anti along the C-O bond of the ester group.
- Lee, Chang Kiu,Yu, Ji Sook,Kim, Sun Hee
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p. 835 - 841
(2007/10/03)
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- PHOTOCYCLISATION OF KETO-LACTAMS. A NEW SYNTHESIS OF FUNCTIONALIZED 1-AZA-BICYCLO(X.Y.0.)ALKANES
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A series of 1-azabicyclo(x.y.0)alkanes has been synthesized using an intramolecular photoreduction.The methodology consists of a regioselective abstraction of a hydrogen α to the nitrogen of an amide by the triplet T1(n, ?*) of a carbonyl derivative.
- Azzouzi, Assia,Dufour, Monique,Gramain, Jean-Claude,Remuson, Roland
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p. 133 - 148
(2007/10/02)
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- 2,2'-Pyrromethene-5-one, its 1- and 1'-mono- and 1,1'-dimethyl homologues; Synthesis, thermal and photochemical reactivity
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2,2'-Pyrromethene-5-one, together with the 1- and 1'-monomethyl and 1,1'-dimethyl homologues are prepared in high yield. 2,2'-Pyrromethene-5-one (1) and its 1'-methyl homologue (2) are obtained in the Z form and the 1-methyl (3) and 1,1'-dimethyl homologue (4) in the E form.All four systems photoisomerize upon irradiation with light (λ > 360 nm> (Fig. 1).Separation of the photoisomeric mixtures provides the geometrical isomers that cannot be obtained via the thermal synthesis.The photoisomers do not isomerize thermally in refluxing methanol.Upon addition of sodium carbonate in methanol the photoisomers are converted back to theoriginal isomers, demonstrating that Z-(1), Z-(2), E-(3) and E-(4) are thermodynamically more stable than E-(1), E-(2), Z-(3) and Z-(4), respectively.The presence of the 1-methyl group in 2,2'-pyrromethene-5-one systems is reflected in the thermodynamics and the photochemistry of these molecules.
- Onkenhout, W.,Koeveringe, J. A. van,Lugtenburg, J.
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p. 106 - 109
(2007/10/02)
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