- Aerobic oxidation of PdII to PdIV by active radical reactants: Direct C-H nitration and acylation of arenes via oxygenation process with molecular oxygen
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A Pd-catalyzed aerobic oxidative C-H nitration and acylation of arenes with simple and readily available tert-butyl nitrite (TBN) and toluene as the radical precursors has been developed. Molecular oxygen is employed as the terminal oxidant and oxygen source to initiate the active radical reactants. Many different directing groups such as pyridine, pyrimidine, pyrazole, pyridol, pyridylketone, oxime, and azo groups can be employed in these novel transformations. The PdII/PdIV catalytic cycle through a radical process is the most likely pathway for these oxidative C-H nitration and acylation reactions.
- Liang, Yu-Feng,Li, Xinyao,Wang, Xiaoyang,Yan, Yuepeng,Feng, Peng,Jiao, Ning
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p. 1956 - 1963
(2015/03/14)
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- Palladium-catalyzed chelation-assisted aromatic C-H nitration: Regiospecific synthesis of nitroarenes free from the effect of the orientation rules
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A palladium-catalyzed chelation-assisted ortho-nitration of aryl C-H bond is described. A range of azaarenes such as 2-arylquinoxalines, pyridines, quinoline, and pyrazoles were nitrated with excellent chemo- and regioselectivity. Using the O-methyl oximyl group as a removable directing group, the regiospecific synthesis of a variety of o-nitro aryl ketones was achieved starting from aryl ketones via a three-step process involving the Pd-catalyzed ipso-nitration of C-H bond as a key step. Mechanistic investigations support a silver-mediated radical mechanism involving Pd((II/III) and/or Pd(II/IV) catalytic cycles under oxidizing conditions.
- Zhang, Wei,Lou, Shaojie,Liu, Yunkui,Xu, Zhenyuan
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p. 5932 - 5948
(2013/07/26)
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- Regiospecific synthesis of nitroarenes by palladium-catalyzed nitrogen-donor-directed aromatic C-H nitration
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Nitration of N-heteroaromatics: The first example of palladium-catalyzed direct ortho-nitration of aryl C-H bonds is described. A range of azaarenes, such as 2-arylquinoxalines, pyridines, pyrazoles, and O-methyl oximes, were nitrated with excellent chemo- and regioselectivity (see scheme; DCE=1,2-dichloroethane). Preliminary mechanistic investigations support a silver-mediated radical mechanism involving palladium(II/III) and/or palladium(II/IV) catalytic cycles under oxidizing conditions. Copyright
- Liu, Yun-Kui,Lou, Shao-Jie,Xu, Dan-Qian,Xu, Zhen-Yuan
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supporting information; experimental part
p. 13590 - 13593
(2011/03/18)
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- Synthesis and antiarrhythmic activity of disubstituted phenylpyridine derivative
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A series of disubstituted phenylpyridine derivatives was synthesized and their antiarrhythmic effects against chloroform-induced ventricular arrhythmias in mice were examined. Among them, 2- and 3-[2-(3- aminobutyramido)-4-(2,2,2-trifluoroethoxy)phenyl]pyridines (23h, 24h) and 3- [2-(3-aminobutyramido)-4-ethoxyphenyl]pyridine (24i) showed potent antiarrhythmic activity. They had approximately twice the potency of mexiletine (III). Compound 24i was selected from this series as a candidate for further development; it was found to have a class I B electrophysiological character and to show a slow kinetic rate-dependent block (RDB) of the sodium channel in cardiac muscle.
- Shigyo,Sato,Shibuya,Takahashi,Yamaguchi,Sonoki,Ohta
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p. 1573 - 1582
(2007/10/02)
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