- Novel η3-allylpalladium-pyridinylpyrazole complex: Synthesis, reactivity, and catalytic activity for cyclopropanation of ketene silyl acetal with allylic acetates
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Novel cationic η3-allylpalladium-pyridinylpyrazole complexes 1a and 1b were synthesized from 3-alkyl-5-(2-pyridinyl)pyrazole and η3-allylpalladium chloride dimer in the presence of AgBF4. Cationic complexes 1a and 1b were converted into neutral complexes 2a and 2b under basic conditions. These complexes were characterized by 1H, 13C, and 15N NMR studies. Neutral complexes 2a and 2b have high catalytic activity for cyclopropanation of ketene silyl acetals with allylic acetates. Comparison of the cationic and neutral complexes and the reaction mechanism of cyclopropanation were discussed.
- Satake, Akiharu,Nakata, Tadashi
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- Nickel-Catalyzed Stereoselective Alkenylation of C(sp3)-H Bonds with Terminal Alkynes
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A nickel-catalyzed stereoselective alkenylation of an unactivated β-C(sp3)-H bond in aliphatic amide with terminal alkynes using 8-aminoquinoline auxiliary is reported for the first time. This reaction displays excellent functional group tolerance with respect to both aliphatic amides and terminal alkynes and features a cheap nickel catalytic system. The 8-aminoquinolyl directing group could be smoothly removed, and the resultant β-styrylcarboxylic acid derivatives could serve as versatile building blocks for further transformation.
- Lin, Cong,Chen, Zhengkai,Liu, Zhanxiang,Zhang, Yuhong
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p. 850 - 853
(2017/02/26)
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- Iminoxyl radical-promoted dichotomous cyclizations: Efficient oxyoximation and aminooximation of alkenes
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A novel iminoxyl radical-involved metal-free approach to vicinal oxyoximation and aminooximation of unactivated alkenes is developed. This method utilizes the dichotomous reactivity of the iminoxyl radical to furnish a general difunctionalization on alkenes using simple tert-butyl nitrite (TBN) as the iminoxyl radical initiator as well the carbon radical trap. By using this protocol, oxime featured 4,5-dihydroisoxazoles and cyclic nitrones were facilely prepared from β,γ- and γ,δ-unsaturated ketoximes, respectively.
- Peng, Xie-Xue,Deng, Yun-Jing,Yang, Xiu-Long,Zhang, Lin,Yu, Wei,Han, Bing
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supporting information
p. 4650 - 4653
(2015/01/08)
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- Intramolecular hydroalkoxylation in Bronsted acidic ionic liquids and its application to the synthesis of (±)-centrolobine
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The SO3H-tethered imidazolium and triazolium salts, nonvolatile and recyclable Bronsted acidic ionic liquids, efficiently mediate intramolecular hydroalkoxylations of alkenyl alcohols. They have been successfully employed in the synthesis of (±)-centrolobine.
- Jeong, Yunkyung,Kim, Do-Young,Choi, Yunsil,Ryu, Jae-Sang
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supporting information; experimental part
p. 374 - 378
(2011/02/28)
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- Asymmetric cyclopropanation of ketene silyl acetal with allylic acetate catalyzed by a palladium complex
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The first asymmetric cyclopropanation of ketene silyl acetal with allylic acetate was achieved. New chiral oxazolidinylpyrazole ligands and their η3-allylpalladium complexes were synthesized. Reaction of cinnamyl acetate with ketene silyl acetal of ethyl isobutylate in the presence of a palladium complex gave a phenyl cyclopropane derivative in 20~ 54%ee.
- Satake, Akiharu,Kadohama, Hitomi,Koshino, Hiroyuki,Nakata, Tadashi
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p. 3597 - 3600
(2007/10/03)
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- Cyclopropanation of ketene silyl acetals with allylic acetates using η3-allylpalladium-pyridinylimidazole catalysts
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Highly selective cyclopropanation of ketene silyl acetals with allylic acetates was carried out in the presence of novel η3-allylpalladium-pyridinylimidazole complexes and sodium acetate in DMSO at room temperature. When cinnamyl acetate was used as an allylic acetate, phenylcyclopropane derivative was obtained stereoselectively in 83% yield.
- Satake, Akiharu,Koshino, Hiroyuki,Nakata, Tadashi
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- Competitive - and -Sigmatropic Rearrangements
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Several cases of the oxy-Cope rearrangement, which typically prefers the -sigmatropic route, are now known to occur in a -sigmatropic fashion.By contrast, the symmetry-allowed thermal rearrangement of carbanions (or their enol derivatives; e.g.,
- Arnold, Richard T.,Kulenovic, Srdanka T.
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p. 891 - 894
(2007/10/02)
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