- Ruthenium-catalyzed formation of pyrazoles or 3-hydroxynitriles from propargyl alcohols and hydrazines
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Functionalized pyrazoles are generated from secondary propragyl alcohols and hydrazines in a ruthenium-catalyzed cascade process, consisting of redox isomerization, Michael addition, cyclocondensation and dehydrogenation steps. The same bifunctional catalyst mediates the conversion of tertiary propargyl alcohols with hydrazine to 3-hydroxynitriles via anti-Markovnikov hydroamination followed by elimination of ammonia.
- Kaufmann, Julia,J?ckel, Elisabeth,Haak, Edgar
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supporting information
p. 91 - 101
(2019/07/09)
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- Copper-catalyzed arylation of nitrogen heterocycles from anilines under ligand-free conditions
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The arylation of pyrazole and derivatives can be achieved by coupling arenediazonium species (formed in situ from anilines) by using a catalytic system that employs low-toxicity and inexpensive copper metal under very mild and ligand-free conditions (T = 20 ° C). From other nitrogen heterocycles, the presence of an additive (NBu4I) significantly improves the efficiency of the catalytic system. These results represent the first examples of C-N bond formation from arenediazonium species.
- Toummini, Dounia,Tlili, Anis,Bergs, Julien,Ouazzani, Fouad,Taillefer, Marc
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supporting information
p. 14619 - 14623
(2015/01/09)
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- Simple copper salt-catalyzed N-arylation of nitrogen-containing heterocycles with aryl and heteroaryl halides
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(Chemical Equation Presented) Relatively mild and highly efficient CuI-catalyzed N-arylation procedures for nitrogen-containing heterocycles (e.g., imidazoles, benzimidazoles, pyrroles, pyrazoles, indoles, triazoles, etc.) with aryl and heteroaryl halides have been developed. The protocols can be performed easily and tolerate a number of functional groups, such as ester, nitrile, nitro, ketone, free hydroxyl, and free primary amine on the aryl halide.
- Zhu, Liangbo,Guo, Peng,Li, Gaocan,Lan, Jingbo,Xie, Rugang,You, Jingsong
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p. 8535 - 8538
(2008/03/11)
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- Regioselective synthesis of 1-aryl-3,4-substituted/annulated-5-(methylthio) pyrazoles and 1-aryl-3-(methylthio)-4,5-substituted/annulated pyrazoles
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Highly efficient and regioselective synthesis of 1-aryl-3,4-substituted/ annulated-5-(methylthio)-pyrazoles and 1-aryl-3-(methylthio)-4,5-substituted/ annulated pyrazoles has been reported via cyclocondensation of arylhydrazines with either α-oxoketene dithioacetals or β-oxodithioesters.
- Peruncheralathan,Khan,Ila,Junjappa
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p. 10030 - 10035
(2007/10/03)
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- Mild conditions for copper-catalysed N-arylation of pyrazoles
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Copper-catalysed N-arylation of pyrazoles with aryl or heteroaryl bromides or iodides, which can include functional substituents, was performed under the mildest conditions yet described, with excellent yields and selectivity, by the use as catalyst of a combination of cuprous oxide with a set of inexpensive, chelating oxime-type ligands not previously known to promote such reactions. Other original bi-, tri- or tetradentate ligands providing nitrogen and/or oxygen as chelating atoms were also successfully tested in this type of arylation. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).
- Cristau, Henri-Jean,Cellier, Pascal P.,Spindler, Jean-Francis,Taillefer, Marc
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p. 695 - 709
(2007/10/03)
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- Phototransposition chemistry of 1-Phenylpyrazole. Experimental and computational studies
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Photophysical and photochemical properties of 1-phenylpyrazole and 3-,4-, and 5-methyl-1-phenylpyrazoles have been investigated. INDO/S calculations agree with experimental measurements which show that the S1 and T1 states of these c
- Pavlik, James W.,Connors, Robert E.,Burns, Douglas S.,Kurzweil, Edyth M.
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p. 7645 - 7652
(2007/10/02)
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- Deacylation of Pyrrole and other Aromatic Ketones
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Ethyl 4-acetyl-3,5-dimethyl-1H-pyrrole-2-carboxylate (1a) reacts rapidly with ethylene glycol in refluxing benzene with p-toluenesulfonic acid or perchloric acid as a catalyst to give ethyl 3,5-dimethyl-1H-pyrrole-2-carboxylate (3) in high yield (96 percent).Various 2- and 3-acylpyrroles can be efficiently deacylated by using this procedure.Other ketones which undergo deacylation include phenyl(2-phenylindol-3-yl)methanone (19), 1-(5-methyl-1-phenylpyrazol-4-yl)ethanone (20), and 2,4-dimethoxybenzophenone.Certain pyrrole ketones where the acyl group is flanked by two ring methyl groups are also cleaved under acidic conditions by using ethanedithiol.
- Moon, M. W.,Wade, R. A.
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p. 2663 - 2669
(2007/10/02)
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