- Cupric Ion Catalyzed Ester Hydrolysis of O-Acetyl-2-pyridinecarboxaldoxime. Nucleophilic Attack by Metal-Bound Water
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The ester hydrolysis of O-acetyl-2-pyridinecarboxaldoxime is catalyzed by Cu2+.Thus, apparent rates for the hydroxide path and the water path are enhanced by 2.2x107 and 1.1x104 times, respectively.Detailed analysis indicates that the Cu2+-bound hydroxide ion or water molecule reacts with the carbonyl caarbon of the complexed ester.Thus, the catalysis includes increases in the effective concentrations of the attacking nucleophiles as well as enhancement in the leaving group ability.Besides, furhter catalysis in the attack of the coordinated water by general bases is suggested.Implications of the present results on the breakdown of the acyl carboxypeptidase A intermediate are discussed.
- Suh, Junghun,Cheong, Minsek,Suh, Myunghyun Paik
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- Synthesis and ferroelectric properties of platinum(II) complexes with chiral isoxazoline ligand
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Four chiral square-planar (SP-4) alkynylplatinum(II) complexes Pt(L)(C≡C-Ph) (1), Pt(L)(C≡C-Ph-Br) (2), Pt(L)(C≡C-Ph-CH 3) (3) and Pt(L)(C≡C-Ph-OCH3) (4) (L = (1S,5S)-6,6-dimethyl-3′-(pyridin-2-yl)-4′H-spiro[bicyclo[3.1.1] heptane-2,
- Zhang, Xiao-Peng,Liu, Jian,Zhang, Jing-Xuan,Huang, Jia-Hao,Wan, Cheng-Zhang,Li, Cheng-Hui,You, Xiao-Zeng
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- The effect of neutral oximes on the reactivation of human acetylcholinesterase inhibited with paraoxon
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Important defense agents against chemical warfare weapons, which are reactivators of human acetylcholinesterase (huAChE) inhibited by neurotoxic organophosphorus compounds (OP), need a reasonable permeation of the hematoencephalic barrier (HB). In this wo
- Ribeiro, Tatiana S.,Prates, Arthur,Alves, Se?rgio R.,Oliveira-Silva, Jefferson J.,Riehl, Carlos A. S.,Figueroa-Villar, J. Daniel
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- A mild system for synthesis of aldoximes and ketoximes in the presence of N-hydroxyphthalimide in aqueous system
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An efficient method for synthesis of oximes from aldehydes or ketones with N-hydroxyphthalimide or N-hydroxysuccinimide in water has been described. It is the first time to utilize NHPI as an oximation reagent to synthesize aldoximes and ketoximes from the corresponding organic carbonyl compounds without other reagents. The reaction tolerates various functional groups and affords the corresponding oximes in 76%–98% yields. The by-product phthalic acid can be recycled from the system. In addition, this method has been successfully applied to the synthesis of the precursor of some pharmacologically active amide molecules.
- Jiang, Xiaoying,Xu, Xiaohe,Lin, Yuyan,Yan, Yiyan,Li, Pingping,Bai, Renren,Xie, Yuanyuan
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supporting information
p. 5879 - 5885
(2018/09/06)
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- 3-methyl-4-oxa-5-azahomoadamantane as an organocatalyst for the aerobic oxidation of primary amines to oximes in water
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A simple and efficient catalytic system for the aerobic oxidation of primary amines into corresponding oximes has been developed, with 3-methyl-4-oxa-5-azahomoadamantane as catalyst, acetaldoxime as co-catalyst and water as solvent. This process, which uses oxygen (O2) as an economic and green oxidant and water as a green solvent, tolerates a wide range of substrates, affording the target oximes in moderate to excellent yields. It was found that high selectivity was achieved when 3-methyl-4-oxa-5-azahomoadamantane was used, and E-type oximes were the only detected products. A possible mechanism for this catalytic process is proposed.
- Yu, Jiatao,Jin, Yong,Lu, Ming
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supporting information
p. 1175 - 1180
(2015/04/22)
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- A novel and efficient catalytic system including TEMPO/acetaldoxime/InCl3 for aerobic oxidation of primary amines to oximes
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A simple and efficient catalytic system including TEMPO/acetaldoxime/InCl3 for aerobic oxidation of primary amines to corresponding oximes by using toluene as the solvent is described. This practical method can use O2 as the economic and green oxidant, tolerate a wide range of substrates, which can afford the target oximes in moderate to excellent yields.
- Yu, Jiatao,Cao, Xiaohua,Lu, Ming
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supporting information
p. 5751 - 5755
(2015/02/02)
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- Novel terpene based 1,4,2-dioxazoles: Synthesis, characterization, molecular properties and screening against Entamoeba histolytica
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In present investigation a series of 20 dioxazole analogues (1-20) were synthesized, characterized and subjected to molecular properties prediction, anti-amoebic screening and cytotoxicity evaluation. Out of the twenty compounds viz. 3,5-substituted-1,4,2-dioxazoles, six compounds have shown IC50 values in the range (1.00-1.10 μM) lower than the standard drug metronidazole (IC50 = 1.45 μM). The toxicological studies of the active compounds on H9c2 rat cardiac myoblasts showed that all compounds were nontoxic. The pKa, and log P values have also been predicted. Compound 8 showed the most promising results based on anti-amoebic evaluation, cytotoxicity studies and physico-chemical properties prediction.
- Younus Wani, Mohmmad,Athar, Fareeda,Salauddin, Attar,Agarwal, Subhash Mohan,Azam, Amir,Choi, Inho,Roouf Bhat, Abdul
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experimental part
p. 4742 - 4752
(2011/11/04)
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- Synthetic access to new carbamate and thiocarbamate derivatives from pyridinecarbaldehyde oximes and hydroxypyridines
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The synthesis of pyridine carbamate and thiocarbamate derivates is described. A series of oxime carbamate and thiocarbamate derivatives were synthesized by the addition of 2-, 3-, and 4-pyridinecarbaldehyde oximes to isocyanates and isothiocyanates. Furth
- Kocak, Ahmet,Ahmetli, Gulnare,Kocak, Nuriye,Malkondu, Sait,Yaylaci, Aysegul,Kurbanli, Sultan
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experimental part
p. 1629 - 1637
(2011/06/23)
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- Stable freeze-dried pharmaceutical formulation
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The subject of the invention is a freeze-dried formulation consisting of an amorphous phase and a crystalline phase, which is pharmaceutically acceptable, comprising at least one nonprotein active ingredient, characterized in that it contains mannitol and alanine in a ratio R of between 0.1 and 1, R representing the mass of mannitol to the mass of alanine.
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- CATALYTIC Z-E(ANTI-SYN)-ISOMERIZATION OF OXIMES. II. ISOMERIZATION OF Z-PYRIDINE-2-CARBALDEHYDE OXIME IN AQUEOUS SOLUTIONS. AUTOCATALYSIS AND CATALYSIS BY OTHER OXIMES.
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The kinetics of the catalytic Z-E(anti-syn)-isomerization of Z-pyridine-2-carbaldehyde oxime were investigated over a wide range of pH.Depending on the pH value, the reaction can occur either by a proton-catalysed mechanism (pH8-9) or by a noncatalytic mechanism.In the first case the Broensted relationship is characterized by a gradient of 0.47, and in the second by a gradient of 0.61. (The catalysts were the anions of 2-, 3-, and 4-pyridinecarbaldehyde oximes, 1-methyl-3-methylpyridiniocarbaldehyde oxime, hydroxyiminoacetone, diacetyl monoxime, and hydroxylamine and also acetaldehyde oxime, acetone oxime, acetate ion, pyridine, and hydroxylamine.) The similar values for the gradients and activation energies in the two processes are consistent with an isomerization mechanism of the same type (nucleophilic addition) and elimination of the catalyst at the oxime =C=N+= bond of the monoprotonated or nitrone form of the substrate.As isomerization catalyst the anion of Z-2-pyridinecarbaldehyde oxime (the autocatalysis reaction) surpasses the anions of E-aldoximes with similar basicity by more than an order of magnitude in activity.It is supposed that the nucleophilic center of the anions of the Z-aldoximes is the nitrogen atom of the oxime group, and that of the anions of the E-aldoximes is the oxygen atom.
- Ivanenko, A. G.,Somin, I. N.,Kuznetsov, S. G.
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p. 1921 - 1930
(2007/10/02)
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- CATALYTIC Z-E (ANTI-SYN) ISOMERIZATION OF OXIMES I. ISOMERIZATION AND ISOTOPE EXCHANGE OF THE OXIME NITROGEN IN PYRIDINE-2-ALDOXIME IN AQUEOUS SOLUTIONS IN THE PRESENCE OF HYDROXYLAMINE
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The kinetics of Z-E isomerization and 14N/15N isotope exchange of the oxime nitrogen in pyridine-2-carbaldehyde oxime in aqueous solutions in the presence of hydroxylamine were investigated.In the range of pH 2.5-7.5 the isomerization, like isotope exchange, occurs through a gem-hydroxylamine tetrahedral intermediate, formed as a result of nucleophilic attack by the hydroxylamine molecule on the monocationic form of the oxime protonated at the oxime nitrogen.In a weakly alkaline medium (pH 8-9) the substrate is evidently the nitrone form of the electrically neutral oxime.In strong ly alkaline media the hydroxylamine reacts in the form of an anion.In the electrically neutral form it attacks the oxime carbon through the nitrogen atom, and in the anion form it attacks the oxime carbon both through the nitrogenatom and through the oxygen atom.In strongly acidic media (pH2) the isomerization is not accelerated by hydroxylamine; it evidently occurs through a tetrahedral intermediate of the carbinolamine type, formed during attack by a water molecule on the diprotonated form of the oxime.
- Ivanenko, A. G.,Somin, I. N.,Kuznetsov, S. G.
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p. 1252 - 1262
(2007/10/02)
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