- Visible-light mediated stereospecific C(sp2)-H difluoroalkylation of (Z)-aldoximes
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A visible light mediated stereospecific C(sp2)-H difluoroalkylation of (Z)-aldoximes to (E)-difluoroalkylated ketoximes has been described. In this reaction, (hetero)-aromatic and aliphatic difluoroalkylated ketoximes could be obtained with the retention of the configuration of the starting aldoximes. A preliminary mechanism study showed that a difluoromethyl radicalviaan SET pathway was involved.
- Chen, Hua,Deng, Hongmei,Gong, Haiying,Hao, Jian,Li, Mingjie,Peng, Yi,Wan, Wen,Wang, Qian,Zhang, Yifang
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supporting information
p. 7867 - 7874
(2021/09/28)
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- Pt-catalyzed O-silylation of oximes by tri-substituted organosilanes
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Silylated derivatives of oximes are important intermediates in organic synthesis, and have found application in the preparation of various nitrogen containing compounds including nitriles, amines, nitrones, and hydroxylamines. An efficient method for the
- Bhatt, Shreeja V.,Bhatt, Shreya V.,Fotie, Jean
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supporting information
p. 1636 - 1639
(2019/06/04)
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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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- Novel chemoenzymatic oxidation of amines into oximes based on hydrolase-catalysed peracid formation
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The efficient transformation of benzylamines into the corresponding oximes has been described by means of a chemoenzymatic process. This strategy is based on a two-step sequence developed in one-pot at 30 °C and atmospheric pressure. First, the formation of a reactive peracid intermediate occurs by means of a lipase-catalysed perhydrolysis reaction, and then this peracid acts as a chemical oxidising agent of the amines. A total of nine ketoximes were isolated in high purity after a simple extraction protocol (90-98% isolated yield), while for the eleven synthesised aldoximes a further column chromatography purification was required (71-82% isolated yield). In all cases excellent selectivities were attained, offering a practical method for amine oxidation in short reaction times (1 hour). The environmental impact of the process was analysed and compared with a recently published alternative chemical synthesis, finding for this metric a good E-factor value.
- Méndez-Sánchez, Daniel,Lavandera, Iván,Gotor, Vicente,Gotor-Fernández, Vicente
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p. 3196 - 3201
(2017/04/21)
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- CuH-Catalyzed Regioselective Intramolecular Hydroamination for the Synthesis of Alkyl-Substituted Chiral Aziridines
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This report details a general and enantioselective means for the synthesis of alkyl-substituted aziridines. This protocol offers a direct route for the synthesis of alkyl-substituted chiral aziridines from achiral starting materials. Readily accessed ally
- Wang, Haoxuan,Yang, Jeffrey C.,Buchwald, Stephen L.
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supporting information
p. 8428 - 8431
(2017/07/06)
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- METHOD FOR PRODUCING ALDOXIME COMPOUND
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PROBLEM TO BE SOLVED: To provide a method for producing an aldoxime compound using no expensive catalysts and reagents and also requiring no severe reaction conditions. SOLUTION: There is provided a method for producing an aldoxime compound containing a process where an aldehyde compound and an oxime compound are brought into trans oximation reaction in the presence of perchloric acid and/or the metallic salt of perchloric acid in an organic solvent and water. The metallic salt of perchloric acid is preferably ferric perchlorate, cobalt perchlorate, nickel perchlorate, zinc perchlorate, aluminum perchlorate or calcium perchlorate. Also, the organic solvent is preferably methylene chloride and/or ethylene dichloride. SELECTED DRAWING: None COPYRIGHT: (C)2016,JPOandINPIT
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Paragraph 0027; 0035; 0037; 0039-0040
(2018/10/16)
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- Br?nsted acid catalyzed transoximation reaction: Synthesis of aldoximes and ketoximes without use of hydroxylamine salts
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The transoximation reaction enables the transfer of an oxime to a carbonyl compound and is catalyzed by transoximase in the pupae of the silkworm. Inspired by this bio-synthetic pathway, we achieved the transoximation of oximes to aldehydes and ketones catalyzed by a Br?nsted acid under mild conditions. Hydroxylamine salt, which necessitates a stoichiometric amount of base, was not required. NMR analysis clarified that this reaction proceeded through hydroxylamines generated by the successive hydrolysis of the oxime in situ. In addition, an environmentally benign method for catalytic transoximation was demonstrated in aqueous medium on a one hundred gram scale and the reaction filtrate containing the catalyst was recovered and reused over 10 times.
- Hyodo, Kengo,Togashi, Kosuke,Oishi, Naoki,Hasegawa, Genna,Uchida, Kingo
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supporting information
p. 5788 - 5793
(2016/11/06)
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- Electrochemical tandem synthesis of oximes from alcohols using KNO 3 as the nitrogen source, mediated by tin microspheres in aqueous medium
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Electrochemical oximation of alcohols was realized with KNO3 as the nitrogen source mediated by tin microspheres.
- Zhang, Li,Chen, He,Zha, Zhenggen,Wang, Zhiyong
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supporting information; experimental part
p. 6574 - 6576
(2012/07/30)
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- NEW POLYMORPHIC FORMS OF N-[4-(TRIFLUOROMETHYL)BENZYL]-4-METHOXYBUTYRAMIDE
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Crystalline polymorphic forms of a compound of formula N-[4-(trifluoromethyl)benzyl]-4-methoxybutyramide are described. The two polymorphic forms, named polymorphic Form A and polymorphic Form B, can be used in the treatment of drug addiction and alcoholism and have very good stability. Methods for preparing the polymorphic forms are also described.
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Page/Page column 10
(2009/06/27)
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- Potent inhibitors of lipoprotein-associated phospholipase A2: Benzaldehyde O-heterocycle-4-carbonyloxime
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A series of multi-substituted oximes were prepared and their potencies for inhibiting lipoprotein-associated phospholipase A2 (Lp-PLA2) activity were evaluated in vitro. Among them, compounds 3a, 3b, and 3m were identified to display a micromolar potency for inhibiting Lp-PLA2 in whole human plasma and isolated human LDL. Based on these results, structure-activity relationship was studied on modification of three parts of R1, R2, and R3 to identify a potent pharmacophore for Lp-PLA2. In an attempt to introduce various functional groups at R2 and R3, we discovered that replacement of less lipophilic groups led to an increase of inhibitory activity. Among the tested oxime derivatives, cyano- and morpholino-substituted analogue 4f at R2 and R3 had the highest potency with an IC50 value of 0.05 μM in whole human plasma.
- Jeong, Hyung Jae,Park, Yong-Dae,Park, Ho-Yong,Jeong, Il Yun,Jeong, Tae-Sook,Lee, Woo Song
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p. 5576 - 5579
(2007/10/03)
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- Effect of structure in benzaldehyde oximes on the formation of aldehydes and nitriles under photoinduced electron-transfer conditions
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(Chemical Equation Presented) The mechanistic aspects of the photosensitized reactions of a series of benzaldehyde oximes (1a-o) were studied by steady-state (product studies) and laser flash photolysis methods. Nanosecond laser flash photolysis studies have shown that the reaction of the oxime with triplet chloranil (3CA) proceeds via an electron-transfer mechanism provided the free energy for electron transfer (ΔGET) is favorable; typically, the oxidation potential of the oxime should be below 2.0 V. Substituted benzaldehyde oximes with oxidation potentials greater than 2.0 V quench 3CA at rates that are independent of the substituent and the oxidation potential. The most likely mechanism under these conditions is a hydrogen atom transfer mechanism as this reaction should be dependent on the O-H bond strength only, which is virtually the same for all oximes. Product studies have shown that aldoximes feact to give both the corresponding aldehyde and the nitrile. The important intermediate in the aldehyde pathway is the iminoxyl radical, which is formed via an electron transfer-proton transfer (ET-PT) sequence (for oximes with low oxidation potentials) or via a hydrogen atom transfer (HAT) pathway (for oximes with larger oxidation potentials). The nitriles are proposed to result from intermediate iminoyl radicals, which can be formed via direct hydrogen atom abstraction or via an electron-transfer-proton- transfer sequence. The experimental data seems to support the direct hydrogen atom abstraction as evidenced by the break in linearity in the plot of the quenching rates against the oxidation potential, which suggests a change in mechanism. The nitrile product is favored when electron-accepting substituents are present on the benzene ring of the benzaldehyde oximes or when the hydroxyl hydrogen atom is unavailable for abstraction. The latter is the case in pyridine-2-carboxaldoxime (2), where a strong intramolecular hydrogen bond is formed. Other molecules that form weaker intramolecular hydrogen bonds such as 2-furaldehyde oxime (3) and thiophene-2-carboxaldoxime (4) tend to yield increasing amounts of aldehyde.
- De Lijser, H.J. Peter,Hsu, Susan,Marquez, Bernadette V.,Park, Adriana,Sanguantrakun, Nawaporn,Sawyer, Jody R.
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p. 7785 - 7792
(2007/10/03)
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- Reactivity of p-substituted benzaldoximes in the cleavage of p-nitrophenyl acetate: Kinetics and mechanism
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Eleven p-substituted benzaldoximes (p-XC6H4CH=NOH, where X = H, CH3, CF3, F, Cl, Br, OCH3, N(CH3)2, COOCH3, CN, NO2) have been synthesized and their dissociation constants determined in 10% (v/v) aqueous dioxane at 35°C. Under the same conditions, the pseudofirst order rate constants kobs of their reactions with p-nitrophenyl acetate (PNPA) were measured at pH values from 7.8 to 10.8 and at concentrations c oxime ranging from 0 to 4:00 x 10-3 mol l-1. The kinetic model and mechanism of the said reaction was proposed by means of mathematical statistical modelling of the dependences of kobs on pH and coxime. The mechanism involves a pre-equilibrium (k -1/k1) in which PNPA forms a tetrahedral intermediate (THI) with the deprotonated form of oxime. In the given medium, THI is in equilibrium with the non-reactive conjugated acid THIH (dissociation constant Ka,THIH) which is stabilized by intramolecular hydrogen bond. Depending on pH, the rate-limiting step consists either in formation of THI from educts (pH a,oxime) or in its spontaneous (k 2) and oxime-catalyzed (k3, general acid catalysis) decomposition to products (pH > pKa/oxime). Evaluation of substituent effects on dissociation constants (Ka,oxime) of the oximes showed that there is no direct conjugation between the substituent and the reaction centre (the found reaction constant ρ(Ka,oxime) = 0.91). The transmission coefficient of the transfer of these effects through C=N-O grouping corresponds approximately to one bond. The reaction constants in the Hammett equation obtained from the regression model are: ρ(k -1Ka,THIH/k1) = 1.29, ρ(k2K a,THIH) = 0.20 and ρ(k3Ka,THIH) = 0.67. These reaction constants have been discussed with the regard to the reaction mechanism suggested.
- Picha, Jan,Cibulka, Radek,Hampl, Frantisek,Liska, Frantisek,Parik, Patrik,Pytela, Oldrich
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p. 397 - 413
(2007/10/03)
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- X=Y-ZH systems as potential 1,3-dipoles. Part 56: Cascade 1,3-azaprotio cyclotransfer-cycloaddition reactions between aldoximes and divinyl ketone: The effect of oxime E/Z isomerism on cycloaddition stereoselectivity
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The cascade 1,3-azaprotiocyclotransfer (1,3-APT)-1,3-dipolar-cycloaddition (1,3-DC) reaction between aldoximes and divinyl ketone affords mixtures of exo and endo-isomers of substituted 1-aza-7-oxabicyclo[3.2.1]octan-4-ones, the ratio of which is dependent on the E/Z geometry of the starting oxime and its ability to isomerise under the thermal reaction conditions.
- Blackwell, Mark,Dunn, Peter J,Graham, Alison B,Grigg, Ronald,Higginson, Paul,Saba, Imaad S,Thornton-Pett, Mark
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p. 7715 - 7725
(2007/10/03)
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- Imines and Derivatives. Part 20. N-Phosphinoyloxaziridines: Synthesis and Structural Characterisation by Nuclear Magnetic Resonance Spectroscopy and a Crystal Structure of 3-(4-Chlorophenyl)-2-(diphenylphosphinoyl)oxaziridine
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The preparation of a new class of oxaziridines containing an N-phosphinoyl group is described.The compounds were obtained by peroxyacid oxidation of N-phosphinoyl imines under basic or neutral conditions, and characterised by n.m.r. spectroscopy.Revelant 2JPC, 3JPH, and 1JCH coupling constants are reported.An X-ray structure analysis of the title compound establishes that the 2-diphenylphosphinoyl group is trans to the 3-aryl ring.The P-N bond length (1.76 Angstroem) is abnormally high for an aminophosphorus(v) compound and the nitrogen atom is pyramidal (ΣN=280 deg).This geometry is interpreted in terms of an unusually low degree of ?-bonding between nitrogen and phosphorus due to the high s-character of the nitrogen lone pair.
- Boyd, Derek R.,Malone, John F.,McGuckin, M. Rosaleen,Jennings, W. Brian,Rutherford, Mark,Saket, Barahman M.
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p. 1145 - 1150
(2007/10/02)
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