- Dual photoredox/palladium-catalyzed C-H acylation of 2-arylpyridines with oxime esters
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An unprecedented dual photoredox/palladium-catalyzed iminyl-radical-mediated C-C bond cleavage and directed ortho C-H acylation of 2-arylpyridines by using oxime esters is described. Oxime esters can serve as efficient acyl sources through formation of the corresponding acyl radicals by photoredox-catalyzed iminyl-radical-mediated C-C bond cleavage. This redox-neutral protocol features excellent regioselectivity, a broad substrate scope, and good functional-group tolerance with respect to both components, giving a broad range of aryl ketones with generally good yields.
- He, Bin-Qing,Gao, Yuan,Wang, Peng-Zi,Wu, Hong,Zhou, Hong-Bin,Liu, Xiao-Peng,Chen, Jia-Rong
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supporting information
p. 373 - 377
(2020/09/11)
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- Visible-Light Photoredox-Catalyzed Dicarbofunctionalization of Styrenes with Oxime Esters and CO2: Multicomponent Reactions toward Cyanocarboxylic Acids and γ-Keto Acids
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A photoredox-catalyzed dicarbofunctionalization of styrenes with oxime esters and CO2 has been achieved. Notably, a series of four-, five-, or six-membered cyclic ketone oximes worked well to furnish a wide range of ε-, ζ-, and η-cyanocarboxylic acids in good yields. Furthermore, a series of γ-keto acids also could be obtained by employing acyclic ketone oxime esters as the carbonyl radical precursor. It provides convergent access to diverse biologically important cyanocarboxylic and γ-keto acids.
- Bai, Junxue,Li, Miao,Zhou, Cong,Sha, Yu,Cheng, Jiang,Sun, Jianwei,Sun, Song
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supporting information
p. 9654 - 9658
(2021/12/14)
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- Reactivity studies of carbon, phosphorus and sulfur-based acyl sites with tertiary oximes in gemini surfactants
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Kinetic studies of the reactions of tertiary oximes (monoisonitroso acetone; MINA and butane 2,3 dione monooxime; BDMO) with some carboxylate (p-nitrophenyl acetate and p-nitrophenyl benzoate), phosphate (p-nitrophenyl diphenyl phosphate and bis (2,4-dini
- Gupta, Bhanushree,Sharma, Rahul,Singh, Namrata,Karpichev, Yevgen,Satnami, Manmohan L.,Ghosh, Kallol K.
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p. 632 - 642
(2013/08/23)
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- Kinetic study of the reactions of p-nitrophenyl acetate and p-nitrophenyl benzoate with oximate nucleophiles
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The reactions of p-nitrophenyl acetate (PNPA) and p-nitrophenyl benzoate (PNPB) with α-nucleophile oximates, that is, butane 2,3-dione monoximate, pralidoximate, and other oximates have been studied in the presence of different cationic surfactants. The f
- Tiwari, Shuchi,Kolay, Sancheeta,Ghosh, Kallol K.,Kuca, Kamil,Marek, Jan
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experimental part
p. 57 - 64
(2009/04/18)
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- Comparative nucleophilic reactivities in carboxylate, phosphinate, and thiophosphate esters cleavage
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Nucleophilic substitution reaction of p-nitrophenyl acetate (PNPA),p-nitrophenyldiphenyl phosphinate, and pesticide parathion with different a-nucleophiles [I] have been studied at 27°C in different pH in the presence of a novel cationic surfactant. [image omitted] The kinetic study was performed spectrophotometrically under pseudo-first order conditions with the α-nucleophile in excess. The pKa of nucleophiles have also been determined by kinetic method. In the presence of surfactant, the rate constant increased with increasing surfactant concentration up to a limiting value. This behavior has been analyzed in quantitative terms on the basis of pseudo-phase model of micellar catalysis. Finally the nucleophilic reactivity of hydroxamate ions has been compared with other α-nucleophiles, like oxime, hydroxybenzotriazole, and 2-iodosobenzoic acid (IBA). The order of cleavage of electrophilic centers, that is, C=O, P=O, and P=S have also been discussed. Copyright
- Ghosh, Kallol K.,Bal, Sunita,Kolay, Sancheeta,Shrivastava, Ashish
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scheme or table
p. 492 - 497
(2009/04/04)
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- Solvent effect on the α-effect: Ground-state versus transition-state effects; a combined calorimetric and kinetic investigation
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In a study of the solvent effect on the α-effect, second-order rate constants (kNu-) have been determined spectrophotometrically for reactions of a series of substituted phenyl acetates with butan-2,3-dione monoximate (Ox-, α-nucleop
- Um, Ik-Hwan,Hwang, So-Jeong,Buncel, Erwin
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p. 915 - 920
(2007/10/03)
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- Effect of modification of the electrophilic center on the α effect
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We report on a nucleophilic study of esters R-C(=X)-Y-Ar in which the electrophilic center has been modified by replacing O by S in the leaving group or carbonyl center: 4-nitrophenyl acetate (1), S-4-nitrophenyl thioacetate (2), 4-nitrophenyl benzoate (3), and O-4-nitrophenyl thionobenzoate (4). The studies include O- and S- nucleophiles as well as α nucleophiles in H2O at 25.0 ± 0.1°C. The sulfur nucleophile (4-chlorothiophenoxide, 4-ClPhS-) exhibits significant enhanced reactivity for the reactions with thiol and thione esters 2 and 4 compared with their oxygen analogues 1 and 3. On the contrary, the common nucleophile OH- is much less reactive towards 2 and 4 compared with 1 and 3. The effect of changing both the electrophilic center and the nucleofugic center on the reactivity of the other oxygen nucleophiles is not so significant: 4-chlorophenoxide (4-ClPhO-) is four to six times more reactive in the reactions with thiol and thione esters 2 and 4 compared with their oxygen analogues 1 and 3. The α effects exhibited by butan-2,3-dione monoximate (Ox-) and HOO- are strongly dependent on the nature of the electrophilic center of the substrates, indicating that the difference in the ground-state solvation energy cannot be fully responsible for the α effect. Our results clearly emphasize the strong dependence of the α effect on the substrate structure, notably, the nature of the electrophilic center. The impact of change in the nucleofuge (1-→2) and the electrophilic center (3-→4) on reactivity indicates that anucleophiles will need to be "purpose built" for decontamination and nucleophilic degradation of specific biocides.
- Um, Ik-Hwan,Lee, Ji-Youn,Bae, Sun-Young,Buncel, Erwin
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p. 1365 - 1371
(2007/10/03)
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- Solvent effect on the α-effect for the reactions of aryl acetates with butane-2,3-dione monoximate and p-chlorophenoxide in MeCN-H2O mixtures
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Second-order rate constants have been measured spectrophotometrically for the nucleophilic reactions of three substituted phenyl acetates with butane-2,3-dione monoximate (Ox-) as an α-nucleophile and p-chlorophenoxide (ClPhO-) as co
- Um,Lee,Buncel
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p. 4859 - 4864
(2007/10/03)
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- The origin of the α-effect: Dissection of ground-state and transition- state contributions
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The origin of the α-effect has been probed through a combination of calorimetric and kinetic studies involving butane-2,3-dione monoximate as α- nucleophile and p-chlorophenoxide as normal nucleophile in the reaction with p-nitrophenyl acetate in DMSO-Hs
- Um, Ik-Hwan,Buncel, Erwin
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p. 577 - 582
(2007/10/03)
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- Solvent effect on rate for anionic nucleophilic substitution reaction of 4-nitrophenyl acetate in aqueous acetonitrile
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Second order rate constants have been measured for anionic nucleophilic substitution reactions of 4-nitrophenyl acetate in MeCN-H2O mixtures. The results show rate minima near 30-40 mole % MeCN, which are attributed to changes in solvent structure.
- Um,Lee,Yoon,Kwon
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p. 2023 - 2026
(2007/10/02)
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- Oxime Esters as Novel Irreversible Acyl Transfer Agents for Lipase Catalysis in Organic Media
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Oxime acetates and acrylates are established as efficient irreversible acyl transfer agents for lipase-catalysed transesterification in organic media.
- Ghogare, A.,Kumar, G. Sudesh
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p. 1533 - 1535
(2007/10/02)
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