- Boronic Acid-Catalyzed, Highly Enantioselective Aza-Michael Additions of Hydroxamic Acid to Quinone Imine Ketals
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Boronic acid is one of the most versatile organic molecules in chemistry. Its uses include organic reactions, molecular recognition, assembly, and even medicine. While boronic acid catalysis, which utilizes an inherent catalytic property, has become an important research objective, it still lags far behind other boronic acid chemistries. Here, we report our discovery of a new boronic acid catalysis that enables the aza-Michael addition of hydroxamic acid to quinone imine ketals. By using 3-borono-BINOL as a chiral boronic acid catalyst, this reaction could be implemented in a highly enantioselective manner, paving the way to densely functionalized cyclohexanes.
- Hashimoto, Takuya,Gálvez, Alberto Osuna,Maruoka, Keiji
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- Hydroxamate represents a versatile zinc binding group for the development of new carbonic anhydrase inhibitors
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Hydroxamates (R-CONHOH) have been scarcely investigated as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors (CAIs). An inhibition/structural study of PhCONHOH is reported against all human isoforms. Comparing aliphatic (R = Me and CF3) and aromatic (R = Ph) hydroxamates as CAIs, we prove that CONHOH is a versatile zinc binding group. Depending on the nature of the R moiety, it can adopt different coordination modes to the catalytic ion within the CA active site.
- Di Fiore, Anna,Maresca, Alfonso,Supuran, Claudiu T.,De Simone, Giuseppina
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- Large Stereoelectronic Effect in 1,3-Dehydrohalogenation to form a 1,3-Dipole
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The E-hydroximidoyl chloride (5), prepared on photoisomerisation of (1) to (2) and by subsequent hydrolysis, is shown to lose HCl to give benzonitrile oxide 6*107 fold slower than the Z-isomer (3).
- Hegarty, Anthony F.,Mullane, Maria
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- Synthesis, structure and magnetic properties of phenylhydroxamate-based coordination clusters
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The strategic recombination of preformed coordination clusters in the presence of polymodal bridging ligands has successfully led to the characterisation of five new compounds of structural and magnetic interest. Indeed using the dinuclear complex [M2(H2O)(piv)4(Hpiv)4] (M = Co, Ni; Hpiv = pivalic acid) as starting material and reacting it with phenylhydroxamic acid (H2pha) has yielded the four tetrametallic coordination clusters [Co4(Hpha)2(piv)6(Hpiv)4] (1), [Ni4(Hpha)2(piv)6(Hpiv)2(DMF)2] (2), [Co4(Hpha)2(piv)6(EtOH)2(H2O)2] (3), [Ni4(Hpha)2(piv)6(EtOH)2(H2O)2] (4) and the hexanuclear complex [Co6(Hpha)4(piv)8(EtOH)2]·EtOH (5). All the compounds have been structurally characterised revealing a particular binding mode for the hydroxamate ligand. The study of their magnetic properties has been performed and the modelling of these properties has been done using the appropriate hamiltonians for each compound. The experimental data and their modelling show non-zero spin ground states for compounds 4 and 5.
- Tirfoin, Rmi,Chamoreau, Lise-Marie,Li, Yanling,Fleury, Benoit,Lisnard, Laurent,Journaux, Yves
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- Suicide nucleophilic attack: Reactions of benzohydroxamate anion with bis(2,4-dinitrophenyl) phosphate
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(Chemical Equation Presented) The reaction between the benzohydroxamate anion (BHO-) and bis(2,4-dinitrophenyl)phosphate (BDNPP) has been examined kinetically, and the products were characterized by mass and NMR spectroscopy. The nucleophilic attack of BHO- follows two reaction paths: (i) at phosphorus, giving an unstable intermediate that undergoes a Lossen rearrangement to phenyl isocyanate, aniline, diphenylurea, and O-phenylcarbamyl benzohydroxamate; and (ii) on the aromatic carbon, giving an intermediate that was detected but slowly decomposes to aniline and 2,4-dinitrophenol. Thus, the benzohydroxamate anion can be considered a self-destructive molecular scissor since it reacts and loses its nucleophilic ability.
- Orth, Elisa S.,Da Silva, Pedro L. F.,Mello, Renata S.,Bunton, Clifford A.,Milagre, Humberto M. S.,Eberlin, Marcos N.,Fiedler, Haidi D.,Nome, Faruk
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- Fast and Cysteine-Specific Modification of Peptides, Proteins and Bacteriophage Using Chlorooximes
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This work reports a novel chlorooxime mediated modification of native peptides and proteins under physiologic conditions. This method features fast reaction kinetics (apparent k2=306±4 M?1s?1 for GSH) and exquisite selectivity for cysteine residues. This cysteine conjugation reaction can be carried out with just single-digit micromolar concentrations of the labeling reagent. The conjugates show high stability towards acid, base, and external thiol nucleophiles. A nitrile oxide species generated in situ is likely involved as the key intermediate. Furthermore, a bis-chlorooxime reagent is synthesized to enable facile Cys-Cys stapling in native peptides and proteins. This highly efficient cysteine conjugation and stapling was further implemented on bacteriophage to construct chemically modified phage libraries.
- Chen, Fa-Jie,Zheng, Mengmeng,Nobile, Vincent,Gao, Jianmin
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- Silver-Catalyzed Acyl Nitrene Transfer Reactions Involving Dioxazolones: Direct Assembly of N-Acylureas
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Dioxazolones and isocyanides are useful synthetic building blocks, and have attracted significant attention from researchers. However, the silver-catalyzed nitrene transfer reaction of dioxazolones has not been investigated to date. Herein, a silver-catalyzed acyl nitrene transfer reaction involving dioxazolones, isocyanides, and water was realized in the presence of Ag2O to afford a series of N-acylureas in moderate to good yields.
- Yang, Zheng-Lin,Xu, Xin-Liang,Chen, Xue-Rong,Mao, Zhi-Feng,Zhou, Yi-Feng
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p. 648 - 652
(2020/12/21)
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- Palladium-Catalyzed 5-exo-dig Cyclization Cascade, Sequential Amination/Etherification for Stereoselective Construction of 3-Methyleneindolinones
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An cascade intramolecular 5-exo-dig cyclization of N-(2-iodophenyl)propiolamides and sequential amination/etherification (with N-hydroxybenzamides, phenyl hydroxycarbamate) protocol for the synthesis of amino- and phenoxy-substituted 3-methyleneindolinones using unexpensive Pd(PPh3)4 as catalyst has been developed. The protocol enables the assembly of structurally important oxindole cores featuring moderate functional group tolerance (particularly the halo group), affording a broad spectrum of products with diverse substituents in good to excellent yields. (Figure presented.).
- Zuo, Youpeng,He, Xinwei,Tang, Qiang,Hu, Wangcheng,Zhou, Tongtong,Hu, Wenbo,Shang, Yongjia
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p. 2117 - 2123
(2020/12/22)
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- Hydroxamates as a potent skeleton for the development of metallo-β-lactamase inhibitors
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Bacterial resistance caused by metallo-β-lactamases (MβLs) has become an emerging public health threat, and the development of MβLs inhibitor is an effective way to overcome the resistance. In this study, thirteen novel O-aryloxycarbonyl hydroxamates were constructed and assayed against MβLs. The obtained molecules specifically inhibited imipenemase-1 (IMP-1) and New Delhi metallo-β-lactamase-1, exhibiting an IC50 value in the range of 0.10–18.42 and 0.23–22.33?μM, respectively. The hydroxamate 5 was found to be the most potent inhibitor, with an IC50 of 0.1 and 0.23?μM using meropenem and cefazolin as substrates. ICP-MS analysis showed that 5 did not coordinate to the Zn(II) ions at the active site of IMP-1, while the rapid dilution, thermal shift and MALDI-TOF assays revealed that the hydroxamate formed a covalent bond with the enzyme. Cytotoxicity assays indicated that the hydroxamates have low toxicity in MCF-7 cells. This work provided a potent scaffold for the development of MβLs inhibitors.
- Chen, Cheng,Chigan, Jia-Zhu,Ding, Huan-Huan,Li, Jia-Qi,Liu, Lu,Xu, Yin-Sui,Yang, Ke-Wu
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- Thioether-Directed NiH-Catalyzed Remote γ-C(sp3)-H Hydroamidation of Alkenes by 1,4,2-Dioxazol-5-ones
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A NiH-catalyzed thioether-directed cyclometalation strategy is developed to enable remote methylene C-H bond amidation of unactivated alkenes. Due to the preference for five-membered nickelacycle formation, the chain-walking isomerization initiated by the NiH insertion to an alkene can be terminated at the γ-methylene site remote from the alkene moiety. By employing 2,9-dibutyl-1,10-phenanthroline as the ligand and dioxazolones as the reagent, the amidation occurs at the γ-C(sp3)-H bonds to afford the amide products in up to 90% yield (>40 examples) with remarkable regioselectivity (up to 24:1 rr).
- Chen, Qishu,Du, Bingnan,Ouyang, Yuxin,Yu, Wing-Yiu
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supporting information
p. 14962 - 14968
(2021/09/29)
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- Photochemical Activation of Aromatic Aldehydes: Synthesis of Amides, Hydroxamic Acids and Esters
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A cheap, facile and metal-free photochemical protocol for the activation of aromatic aldehydes has been developed. Utilizing thioxanthen-9-one as the photocatalyst and cheap household lamps as the light source, a variety of aromatic aldehydes have been activated and subsequently converted in a one-pot reaction into amides, hydroxamic acids and esters in good to high yields. The applicability of this method was highlighted in the synthesis of Moclobemide, a drug against depression and social anxiety. Extended and detailed mechanistic studies have been conducted, in order to determine a plausible mechanism for the reaction.
- Nikitas, Nikolaos F.,Apostolopoulou, Mary K.,Skolia, Elpida,Tsoukaki, Anna,Kokotos, Christoforos G.
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supporting information
p. 7915 - 7922
(2021/05/03)
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- P(III)-Assisted Electrochemical Access to Ureas via in situ Generation of Isocyanates from Hydroxamic Acids
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An external oxidant-free protocol for the generation of isocyanates from hydroxamic acids assisted by trivalent phosphine under mild electrochemical conditions was reported. The process started with the anodic oxidation of hydroxamic acids, followed by reacting with phosphine to form corresponding alkoxyphosphoniums and subsequent rearrangement with the release of tri-substituted phosphine oxide as the driving force to give isocyanates, which were trapped by N-based nucleophiles to produce various ureas. This method provides a broadly applicable procedure to access isocyanate intermediates under mild electrochemical conditions.
- Meng, Haiwen,Sun, Kunhui,Xu, Zhimin,Tian, Lifang,Wang, Yahui
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supporting information
p. 1768 - 1772
(2021/03/26)
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- Alternating Current Electrolysis as Efficient Tool for the Direct Electrochemical Oxidation of Hydroxamic Acids for Acyl Nitroso Diels–Alder Reactions
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The acyl nitroso Diels–Alder reaction of 1,3-dienes with electrochemically oxidised hydroxamic acids is described. By using alternating current electrolysis, their typical electro-induced decomposition could be suppressed in favour of the 1,2-oxazine cycloaddition products. The reaction was optimised using Design of Experiments (DoE) and a sensitivity test was conducted. A mixture of triethylamine/hexafluoroisopropanol served as supporting electrolyte in dichloromethane, thus giving products of high purity after evaporation of the volatiles without further purification. The optimised reaction conditions were applied to various 1,3-dienes and hydroxamic acids, giving up to 96 % isolated yield.
- F?hrmann, Jan,Hilt, Gerhard
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supporting information
p. 20313 - 20317
(2021/08/12)
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- Direct synthesis of benzoxazinones via Cp*Co(III)-catalyzed C–H activation and annulation of sulfoxonium ylides with dioxazolones
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A highly novel and direct synthesis of benzoxazinones was developed via Cp*Co(III)-catalyzed C–H activation and [3 + 3] annulation between sulfoxonium ylides and dioxazolones. The reaction is conducted under base-free conditions and tolerates various functional groups. Starting from diverse readily available sulfoxonium ylides and dioxazolones, a variety of benzoxazinones could be synthesized in one step in 32%-75% yields.
- Yu, Yongqi,Xia, Zhen,Wu, Qianlong,Liu, Da,Yu, Lin,Xiao, Yuanjiu,Tan, Ze,Deng, Wei,Zhu, Gangguo
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supporting information
p. 1263 - 1266
(2020/10/08)
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- Synthesis of sulfimides and N-Allyl-N-(thio)amides by Ru(II)catalyzed nitrene transfer reactions of N-acyloxyamides
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The N-acyloxyamides were employed as effective N-acyl nitrene precursors in reactions with thioethers under the catalysis of a commercially available Ru(II) complex, from which a variety of sulfimides were synthesized efficiently and mildly. If an allyl group is contained in the thioether precursor, the [2,3]-sigmatropic rearrangement of the sulfimide occurs simultaneously and the N-allyl-N-(thio)amides were obtained as the final products. Preliminary mechanistic studies indicated that the Ru-nitrenoid species should be a key intermediate in the transformation.
- Zhang, Xinyu,Lin, Bo,Chen, Jianhui,Chen, Jiajia,Luo, Yanshu,Xia, Yuanzhi
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supporting information
p. 819 - 825
(2021/02/01)
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- Palladium-catalyzed cascade decarboxylative amination/6- endo-dig benzannulation of o-alkynylarylketones with n-hydroxyamides to access diverse 1-naphthylamine derivatives
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An efficient and practical one-pot strategy to produce highly substituted 1-naphthylamines via sequential palladium-catalyzed decarboxylative amination/intramolecular 6-endo-dig benzannulation reactions has been described. In this reaction, a broad range of electron-rich, electron-neutral, and electron-deficient o-alkynylarylketones react well with N-hydroxyl aryl/alkylamides to give a diversity of 1-naphthylamines in good to excellent yields under mild reaction conditions. The gram-scale synthesis, with benefits such as undiminished product yield and easy transformation, illustrated the practicality of this method.
- Zuo, Youpeng,He, Xinwei,Tang, Qiang,Hu, Wangcheng,Zhou, Tongtong,Shang, Yongjia
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p. 3890 - 3894
(2020/05/18)
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- Divergent Synthesis of Tunable Cyclopentadienyl Ligands and Their Application in Rh-Catalyzed Enantioselective Synthesis of Isoindolinone
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A series of rhodium complexes bearing sterically and electronically tunable cyclopentadienyl ligands, prepared by utilizing Co2(CO)8-mediated [2+2+1] cyclization as a key step, were synthesized. In the presence of 2.5 mol% of CpmRh4, unprecedented enantioselective [4+1] annulation reaction of benzamides and alkenes was achieved with a broad substrate scope under mild reaction conditions, providing a variety of isoindolinones with excellent regio-and enantioselectivity (up to 94% yield, 97:3 er). Preliminary mechanistic studies suggest that the reaction involves an oxidative Heck reaction and an intramolecular enantioselective alkene hydroamination reaction.
- Cui, Wen-Jun,Wu, Zhi-Jie,Gu, Qing,You, Shu-Li
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p. 7379 - 7385
(2020/08/19)
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- Experimental and computational studies on hydroxamic acids as environmental friendly chelating corrosion inhibitors for mild steel in aqueous acidic medium
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In the present study, three hydroxamic acids (HAs) namely acetohydroxamic acid (AHA), benzohydroxamic acid (BHA) and oxalohydroxamic acid (OHA) were synthesized, characterized and used as inhibitors for mild steel corrosion in1 M HCl using chemical, electrochemical, surface and computational methods. Results of the studies show that the HAs act as effective corrosion inhibitors and their inhibition efficiencies follow the order: OHA (96.37%) > BHA (95.69%) > AHA (93.29%). EIS study showed that studied HAs act as interface type inhibitors. Polarization study revealed that HAs demonstrate mixed-type corrosion inhibitors characteristics and adsorb on the active sites of metallic surface. Adsorption of HAs on metal-1 M HCl interfaces followed the Langmuir adsorption isotherm model. Surface morphological analyses of inhibited and uninhibited metallic surface were carried out using SEM-EDX and XRD methods. DFT analyses showed that studied compounds act as chelating type of ligands. Effect of Keto-enol tautomerism and different possible conformational isomers on metallic corrosion inhibition was demonstrated. The conformational isomers in which >C=O and –OH (hydroxyl) groups present in same side behave as chelating ligands and form relatively more stable complex than that of conformational isomers in which >C=O and –OH groups present in opposite side. Experimental and DFT studies complimented each other well.
- Al Fantazi, Akram,Asatkar, Ashish,Ebenso, Eno E.,Hussain, Chaudhery Mustansar,Khan, Fahmida,Verma, Chandrabhan,Verma, Dakeshwar Kumar
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- RhIII-Catalyzed C?H Activation of Aryl Hydroxamates for the Synthesis of Isoindolinones
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RhIII-catalyzed C?H functionalization reaction yielding isoindolinones from aryl hydroxamates and ortho-substituted styrenes is reported. The reaction proceeds smoothly under mild conditions at room temperature, and tolerates a range of functional groups. Experimental and computational investigations support that the high regioselectivity observed for these substrates results from the presence of an ortho-substituent embedded in the styrene. The resulting isoindolinones are valuable building blocks for the synthesis of bioactive compounds. They provide easy access to the natural-product-like compounds, isoindolobenzazepines, in a one-pot two-step reaction. Selected isoindolinones inhibited Hedgehog (Hh)-dependent differentiation of multipotent murine mesenchymal progenitor stem cells into osteoblasts.
- Shaaban, Saad,Davies, Caitlin,Merten, Christian,Flegel, Jana,Otte, Felix,Strohmann, Carsten,Waldmann, Herbert
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supporting information
p. 10729 - 10734
(2020/07/25)
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- Co(III)-Catalyzed C-H Amidation of Nitrogen-Containing Heterocycles with Dioxazolones under Mild Conditions
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A cobalt(III)-catalyzed C-8 selective C-H amidation of quinoline N-oxide using dioxazolone as an amidating reagent under mild conditions is disclosed. The reaction proceeds efficiently with excellent functional group compatibility. The utility of the current method is demonstrated by gram scale synthesis of C-8 amide quinoline N-oxide and by converting this amidated product into functionalized quinolines. Furthermore, the developed catalytic method is also applicable for C-7 amidation of N-pyrimidylindolines and ortho-amidation of benzamides.
- Dhiman, Ankit Kumar,Thakur, Ankita,Kumar, Inder,Kumar, Rakesh,Sharma, Upendra
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p. 9244 - 9254
(2020/08/14)
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- Chiral amination sulfoxide and preparation method thereof (by machine translation)
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The invention belongs to the field of organic synthesis, and discloses chiral amination sulfoxide which has the structure of a general formula I. Wherein R is hydrogen or R1 And R2 Each independently selected from one of the following structures: hydrogen, alkyl, alkoxy, ester, trifluoromethyl, trifluoromethoxy, trifluoromethylthio. Halogens, alkynyl groups, alkenyl groups, amino groups, cyano groups, hydroxyl groups, aldehyde groups, carboxyl groups, nitro groups, amide groups, benzene rings, and bonded benzene ring fused rings to naphthalene; R3 Selected from the group consisting of phenyl, optionally substituted phenyl, aryl, heteroaryl, styryl, alkyl, haloalkyl and the like. The method comprises the following steps: forming a complex with a tert-butyl cyclopentadienyl metal iridium complex, forming a complex with the modified chiral proline, and activating C-H bond of enantioselective induced sulfoxide to obtain chiral sulphoxide. The synthetic method disclosed by the invention is high in yield and good in enantioselectivity, and the obtained amidated sulfoxide can be derivatized to obtain a chiral ligand. (by machine translation)
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Paragraph 0245-0250
(2020/11/12)
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- METHOD FOR THE SYNTHESIS OF 3-R-1,4,2-DIOXAZOL-5-ONES TECHNICAL FIELD
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Provided are methods of preparing 3-R-1,4,2-dioxazol-5-one compounds using convenient and efficient methods. Also provided are 3-R-1,4,2-dioxazol-5-one compounds produced using the methods described.
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Paragraph 0064-0066; 0068
(2020/12/25)
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- Hydroxamic acid and preparation method of hydroxamic acid salt
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The invention discloses a preparation method of hydroxamic acid salt. The preparation method comprises the following steps: mixing organic carboxylic ester, hydroxylamine or/and hydroxylamine salt, acatalyst and an inert solvent; and adding alkali and grinding to obtain the hydroxamic acid salt, and adding acid into the hydroxamic acid salt, grinding, centrifuging or filtering to obtain the hydroxamic acid. The process conditions for producing the hydroxamic acid or the hydroxamic acid salt by a grinding method in the prior art are optimized, the inert solvent diesel oil is used for replacingwater or methanol and the inert solvent is recycled after being subjected to centrifugal separation and simple treatment so that the generation of waste liquid is avoided, the use of toxic solvents is avoided and the operation safety is also greatly improved; besides, the material is in a flowing state during the grinding reaction due to the use of the inert solvent,so that the viscous material is prevented from adhering to the inner wall of the reaction container and the grinding medium, the reaction is more uniform, the temperature is more controllable, the reaction efficiency is greatly improved, the discharging is more convenient and the industrial production is facilitated.
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Paragraph 0043-0072; 0078-0082
(2020/04/06)
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- Synthetic method of hydroxamic acid collector
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The invention relates to the technical field of collector synthesis, and particularly provides a synthesis method of a hydroxamic acid collector. The synthesis method of the hydroxamic acid collectorcomprises the following steps: premixing reactant ester and a double-ring phase transfer catalyst DBU, adding the formed mixture into a hydroxylamine salt aqueous solution, reacting under the action of alkali, and adding concentrated sulfuric acid for acidolysis after the reaction is finished, thereby obtaining the hydroxamic acid collector. The synthesis method provided by the invention can significantly improve the reaction conversion rate, and has the advantages of mild reaction conditions, environmental protection, safety, simple post-treatment and less waste generation.
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Paragraph 0035-0041
(2020/07/08)
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- Method for synthesizing hydroximic acid compound
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The invention discloses a method for synthesizing a hydroximic acid compound. The method comprises the step of subjecting an organic carboxylic acid compound with a structure represented by a formula(I) shown in the description and a hydroxylamine compound with a structure represented by a formula (II) shown in the description to a grinding reaction in the presence of a coupling reagent, therebypreparing the hydroximic acid compound with a structure represented by a formula (III) shown in the description. According to the method, the technical problems that a large amount of organic solventis used, the reaction temperature is high, wastes are plenty, the aftertreatment is complicated, environmental protection is adverse and the like are solved, and the method has the advantages that thesource of the raw materials is wide, the cost is low, the operation is simple, the efficiency is high, the product is easy to separate, the yield is high, industrial production is easy to achieve andthe like.
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Paragraph 0065-0075; 0095; 0096
(2019/06/13)
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- Synthesis, characterization and assessment of local anesthetic activity of some benzohydroxamic acids
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In the present investigation, 6 compounds (E1-E6) were synthesized by reaction of ethyl esters of p-substituted benzoic acid with hydroxylamine. The chemical structures of the synthesized hydroxamic acids were verified on the basis of spectral analysis (IR, 1H NMR, 13C NMR and mass spectra). The benzohydroxamic acids were examined for potential local anesthetic activity using foot withdrawal reflex of the frog and benzocaine was used as standard drug. Compounds were tested at two different solvents; 5 % DMSO and 0.65 % NaOH, each solution was tested at three different concentration levels (40, 100 and 200 μg/mL). Local anesthetic activity of the compounds differed according to the concentration level and selected solvent. Compounds E4 and E5 were found to be the most active and were comparable to the standard drug in tested solvents at all investigated concentrations. All compounds displayed an enhanced activity in the the aqueous basic solutions.
- Aldeen, Ekhlas Sheakh,Elsaman, Tilal,Mohamed, Malik Suliman,Adam, Mohamed E.,Mohamed, Magdi Awadalla
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p. 181 - 185
(2018/12/11)
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- Dioxazolones as masked ester surrogates in the Pd(ii)-catalyzed direct C-H arylation of 6,5-fused heterocycles
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A simple and effective Pd(ii)-catalyzed regioselective C(2)-H arylation of 6,5-fused heterocycles with dioxazolones as a masked ester surrogate under mild conditions is reported. The significance of the arylation is highlighted by the new reactivity demonstrated in dioxazolones via proximal C-H activation of the cyclic carbonate of the hydroxamic acid functionality under protic conditions.
- Saxena, Paridhi,Maida, Neha,Kapur, Manmohan
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supporting information
p. 11187 - 11190
(2019/09/30)
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- Straightforward synthesis of 4,5-bifunctionalized 1,2-oxazinanes via Lewis acid promoted regio- and stereo-selective nucleophilic ring-opening of 3,6-dihydro-1,2-oxazine oxides
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Functionalized 1,2-oxazinanes are interesting and valuable heterocycles with potential applications in synthetic and medicinal chemistry. A straightforward strategy for quick access to unprecedented trans-4-hydroxyl-5-azido/cyano/amino 1,2-oxazinanes are developed: N-COR 3,6-dihydro- 1,2-oxazine oxides are prepared with ease from related dihydro- 1,2-oxazines and opened by nucleophiles TMSN3, TMSCN and aryl/alkyl amines. Appropriate Lewis acid catalysts are found playing a vital role for both reaction rate and regioselectivity. The N-COR group can be removed under mild conditions to provide highly desirable NH 1,2-oxazinanes inaccessible via previous methods.
- Huang, Xiu-Rong,Zhang, Yu-Mei,Wan, Ting-Biao,Zhang, Piao,Zhang, Xiu-Xiu,Wang, Fang-Ming,Xu, Defeng,Shen, Mei-Hua,Xu, Hua-Dong
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- Rhodium(iii)-catalyzed cascade reactions of benzoic acids with dioxazolones: Discovery of 2,5-substituted benzoxazinones as AIE molecules
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A rhodium-catalyzed cascade reaction of benzoic acids with 1,4,2-dioxazol-5-ones was studied. The carboxyl group enabled a double C-H amidation followed by further intramolecular cyclization to afford 2,5-substituted benzoxazinones, which exhibited aggregation-induced emission (AIE) properties with a promising excited-state intramolecular proton-transfer (ESIPT) phenomenon.
- Li, Jinbiao,Zhang, Shuaizhong,Lonka, Madhava Reddy,Zhang, Jinquan,Zou, Hongbin
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supporting information
p. 11203 - 11206
(2019/09/30)
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- Carboxylic ester oximationmethod
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The invention discloses method for preparing(iso)hydroxamic acid salt or (iso)hydroxamic acid. The method for preparing (iso)hydroxamic acid salt or (iso)hydroxamic acidcomprises the steps that analkali, a hydroxylamine salt, and an organic carboxylic acid ester are directly subjected to hybrid reaction without an extra solvent, and thusan (iso) hydroxamic acid salt product is obtained; and or after the reaction is completed, a reaction system is cooled, an acid is added to the reaction system to obtain (iso)hydroxamic acid.According to themethod for preparing (iso)hydroxamic acid salt or (iso)hydroxamic acid,the (iso)hydroxamic acid salt or the (iso)hydroxamic acidcan be obtainedwith near atomic economy without additional organic solvents or water being added, environment-friendly effectis achieved, simpleness and efficiency are achieved, and industrial production is advantageous.
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Paragraph 0063-0065
(2019/11/04)
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- Efficient Copper-Catalyzed Multicomponent Synthesis of N-Acyl Amidines via Acyl Nitrenes
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Direct synthetic routes to amidines are desired, as they are widely present in many biologically active compounds and organometallic complexes. N-Acyl amidines in particular can be used as a starting material for the synthesis of heterocycles and have several other applications. Here, we describe a fast and practical copper-catalyzed three-component reaction of aryl acetylenes, amines, and easily accessible 1,4,2-dioxazol-5-ones to N-acyl amidines, generating CO2 as the only byproduct. Transformation of the dioxazolones on the Cu catalyst generates acyl nitrenes that rapidly insert into the copper acetylide Cu-C bond rather than undergoing an undesired Curtius rearrangement. For nonaromatic dioxazolones, [Cu(OAc)(Xantphos)] is a superior catalyst for this transformation, leading to full substrate conversion within 10 min. For the direct synthesis of N-benzoyl amidine derivatives from aromatic dioxazolones, [Cu(OAc)(Xantphos)] proved to be inactive, but moderate to good yields were obtained when using simple copper(I) iodide (CuI) as the catalyst. Mechanistic studies revealed the aerobic instability of one of the intermediates at low catalyst loadings, but the reaction could still be performed in air for most substrates when using catalyst loadings of 5 mol %. The herein reported procedure not only provides a new, practical, and direct route to N-acyl amidines but also represents a new type of C-N bond formation.
- Van Vliet, Kaj M.,Polak, Lara H.,Siegler, Maxime A.,Van Der Vlugt, Jarl Ivar,Guerra, Célia Fonseca,De Bruin, Bas
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supporting information
p. 15240 - 15249
(2019/10/19)
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- Experimental and computational studies on H2O-promoted, Rh-catalyzed transient-ligand-free ortho-C(sp2)-H amidation of benzaldehydes with dioxazolones
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An efficient and convenient ligand-free, rhodium-catalyzed ortho-C(sp2)-H amidation of benzaldehydes with dioxazolones using H2O as the key promoter is described. Using this protocol, a wide range of benzaldehyde substrates were selectively amidated in good to excellent yields with broad functional group compatibility. KIE experiments revealed that the C-H bond activation was likely the rate-limiting step. In addition, computational studies indicated that the catalyst precursor interacted with water and dioxazolones to generate the active catalytic species. Notably, the practicality and efficacy of this method were illustrated by a late-stage amidation of an estrone-derived molecule and further transformations of the amidated product.
- Ding, Jun,Jiang, Wei,Bai, He-Yuan,Ding, Tong-Mei,Gao, Dafang,Bao, Xiaoguang,Zhang, Shu-Yu
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supporting information
p. 8889 - 8892
(2018/08/17)
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- Copper-catalyzed pyrrole synthesis from 3,6-dihydro-1,2-oxazines
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Highly-functionalized pyrroles could be effectively synthesized from 3,6-dihydro-1,2-oxazines using a heterogeneous copper on carbon (Cu/C) under neat heating conditions. Furthermore, the in situ formation of 3,6-dihydro-1,2-oxazines via the hetero Diels-Alder reaction between nitroso dienophiles and 1,3-dienes and the following Cu/C-catalyzed pyrrole synthesis also provided the corresponding pyrrole derivatives in a one-pot manner.
- Yasukawa, Naoki,Kuwata, Marina,Imai, Takuya,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
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supporting information
p. 4409 - 4413
(2018/10/17)
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- Photoinduced one-pot synthesis of hydroxamic acids from aldehydes through in-situ generated silver nanoclusters
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Hydroxamic acids have attracted significant attention due to their widespread use in applied chemistry. In this report, a modified Angeli–Rimini method has been achieved via the visible light-mediated catalytic transformation of a variety of heterocyclic, aromatic and aliphatic aldehydes 1a–j to their corresponding hydroxamic acids 2a–j in 81–93% yield. The unique ability of vitamin K3 as a photoredox catalyst to expedite the development of completely new reaction mechanisms and to enable the construction of challenging carbon–nitrogen bonds has been investigated. It is shown for the first time that the vitamin K3 and aldehyde are largely responsible for rapid in situ reduction of Ag+ ions to catalytic photoluminescent Ag nanoclusters that possess a bandgap energy of 2.87?eV and are less than 2 nm in size. A mechanism for this reaction has been proposed and is supported by UV–Vis, TEM, ESI/MS, FT-IR, 1H NMR and 13C NMR analyses. The investigated method utilizes readily available reagents and produces the hydroxamic acids in high yields without the formation of side products, making it simple, practical and cost-effective.
- Mohamed, Yasser M. A.,Attia, Yasser A.,Solum, Eirik Johansson
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p. 7173 - 7186
(2018/08/17)
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- Synthesis and biological activity of salinomycin-hydroxamic acid conjugates
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Several salinomycin-hydroxamic acid conjugates were designed and synthesized. Most conjugates showed better antiproliferative activities than salinomycin in HT-29 colon cancer, HGC-27 gastric cancer, and especially in MDA-MB-231 triple-negative human breast cancer cells. These conjugates are stable in cell culture media, and they showed much better biological activities than the 1:1 physical mixture with hydroxamic acids and salinomycin. The better membrane permeability and hydrolysis rate of the conjugates may lead to the activity improvements.
- Li, Bo,Wu, Jun,Zhang, Wenxuan,Li, Zhongwen,Chen, Gang,Zhou, Qi,Wu, Song
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p. 1624 - 1626
(2017/03/16)
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- Controlling Plasma Stability of Hydroxamic Acids: A MedChem Toolbox
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Hydroxamic acids are outstanding zinc chelating groups that can be used to design potent and selective metalloenzyme inhibitors in various therapeutic areas. Some hydroxamic acids display a high plasma clearance resulting in poor in vivo activity, though they may be very potent compounds in vitro. We designed a 57-member library of hydroxamic acids to explore the structure-plasma stability relationships in these series and to identify which enzyme(s) and which pharmacophores are critical for plasma stability. Arylesterases and carboxylesterases were identified as the main metabolic enzymes for hydroxamic acids. Finally, we suggest structural features to be introduced or removed to improve stability. This work thus provides the first medicinal chemistry toolbox (experimental procedures and structural guidance) to assess and control the plasma stability of hydroxamic acids and realize their full potential as in vivo pharmacological probes and therapeutic agents. This study is particularly relevant to preclinical development as it allows obtaining compounds equally stable in human and rodent models.
- Hermant, Paul,Bosc, Damien,Piveteau, Catherine,Gealageas, Ronan,Lam, Baovy,Ronco, Cyril,Roignant, Matthieu,Tolojanahary, Hasina,Jean, Ludovic,Renard, Pierre-Yves,Lemdani, Mohamed,Bourotte, Marilyne,Herledan, Adrien,Bedart, Corentin,Biela, Alexandre,Leroux, Florence,Deprez, Benoit,Deprez-Poulain, Rebecca
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p. 9067 - 9089
(2017/11/14)
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- Iminyl-Radicals by Oxidation of α-Imino-oxy Acids: Photoredox-Neutral Alkene Carboimination for the Synthesis of Pyrrolines
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The visible-light-promoted decarboxylation of α-imino-oxy propionic acids for the generation of iminyl radicals has been accomplished through the use of Ir(dFCF3ppy)2(dtbbpy)PF6 as a photoredox catalyst. Different from visible-light-promoted homolysis and single-electron reduction of oxime derivatives, this strategy provides a novel catalytic cycle for alkene carboimination through a sequence comprising N-radical generation, iminyl radical cyclization, intermolecular conjugate addition to a Michael acceptor, and single-electron reduction to afford various pyrroline derivatives in an overall redox-neutral process. The indolizidine alkaloid skeleton could be easily constructed from a pyrroline derivative prepared by this synthetic method.
- Jiang, Heng,Studer, Armido
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supporting information
p. 12273 - 12276
(2017/09/11)
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- Tf2NH-Catalyzed Formal [3 + 2] Cycloaddition of Ynamides with Dioxazoles: A Metal-Free Approach to Polysubstituted 4-Aminooxazoles
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An unprecedented Tf2NH-catalyzed formal [3 + 2] cycloaddition of ynamides with dioxazoles was developed to construct various polysubstituted 4-aminooxazoles. This approach features a metal-free catalytic bimolecular assembly of oxazole motifs, a low-cost catalyst, exceptionally mild reaction conditions, a very short reaction time, a broad substrate scope, and high efficiency. This metal-free protocol may find applications in pharmaceutical-oriented synthesis.
- Zhao, Yingying,Hu, Yancheng,Wang, Chunxiang,Li, Xincheng,Wan, Boshun
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p. 3935 - 3942
(2017/04/11)
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- Product Control using Substrate Design: Ruthenium-Catalysed Oxidative C?H Olefinations of Cyclic Weinreb Amides
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A new class of Weinreb amides has been developed as directing groups for the ruthenium-catalysed regioselective oxidative C?H olefination. The new Weinreb amides successfully inhibit the N?O bond reductive cleavage usually associated with the cationic ruthenium system, thereby keeping intact the synthetic utility of Weinreb amides. Mechanistic studies reveal interesting aspects of the directing group capabilities of Weinreb amides when compared to simple amides of similar structures.
- Das, Riki,Kapur, Manmohan
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supporting information
p. 16986 - 16990
(2016/11/17)
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- An Environmentally Sustainable Mechanochemical Route to Hydroxamic Acid Derivatives
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An operationally simple, and cost efficient conversion of carboxylic acids into hydroxamic acid derivatives via a high-energy mechanochemical activation is presented. This ball milling methodology was applied to a wide variety of carboxylic acids dramatically improving purification issues associated with this class of molecules, which still remain one of the main bottlenecks of classical methodologies. (Figure presented.).
- Mocci, Rita,De Luca, Lidia,Delogu, Francesco,Porcheddu, Andrea
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p. 3135 - 3144
(2016/10/09)
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- Novel synthesis method of Istaroxime
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The invention belongs to the field of pharmaceutical chemistry, and discloses a novel synthesis method of Istaroxime. The method comprises the following steps: by using dehydrogenated epiandrosterone as an initial raw material, carrying out epoxidation, ring opening, reduction, oxidation and other reactions to prepare an intermediate M-06; by using ethyl benzoate as an initial raw material, reacting the ethyl benzoate with hydroxylamine hydrochloride to obtain phenyl hydroximic acid, carrying out hydrochlorination and chlorination by using ethanolamine as a raw material to obtain dichloroacetate, and carrying out substitution, hydrolysis and other reactions on the dichloroacetate and the phenyl hydroximic acid to obtain an intermediate M-11; and finally, reacting the M-06 with the M-11 to obtain the end product Istaroxime. According to the method, in the intermediate M-06 synthesis process, the polarity of all the intermediates has great differences from that of the impurities and reaction reagents; and in the intermediate 11 synthesis process, the active spots capable of participating in the chemical reaction in the reaction substrate are simple. Therefore, the method can achieve the requirements without carrying out column chromatography purification, thereby simplifying the synthesis after-treatment process.
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Paragraph 0115; 00116; 0117; 0118; 0119; 0120-0122
(2016/10/10)
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- A facile and rapid preparation of hydroxamic acids by hydroxylaminolysis using DBU as base
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While there are many protocols for the preparation of hydroxamic acids from their corresponding carboxylic acid or carboxylic ester precursors, most use strong mineral bases that can lead to carboxylic acid impurities that can be difficult to remove using standard chromatographic techniques. This problem is exacerbated when the carbonyl group is hindered. Herein, we communicate a robust hydroxylaminolysis protocol for the preparation of hydroxamic acids in high yield and purity.
- Beillard, Audrey,Bhurruth-Alcor, Yushma,Bouix-Peter, Claire,Bouquet, Karinne,Chambon, Sandrine,Clary, Laurence,Harris, Craig S.,Millois, Corinne,Mouis, Grégoire,Ouvry, Gilles,Pierre, Romain,Reitz, Arnaud,Tomas, Loic
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supporting information
p. 2165 - 2170
(2016/05/02)
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- A base-mediated self-propagative Lossen rearrangement of hydroxamic acids for the efficient and facile synthesis of aromatic and aliphatic primary amines
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A variety of aromatic and aliphatic hydroxamic acids were converted to the corresponding primary amines via base-mediated rearrangement. This rearrangement could proceed with less than 1 equiv. of K2CO3 in polar solvents under thermal conditions with no external reagents. This rearrangement has several features including no external activating agents needed for promoting the rearrangement, less than one equivalent of a base is sufficient for the reaction, and a clean reaction in which only carbon dioxide is produced as a by-product. A self-propagating mechanism via an isocyanate intermediate is proposed and elementary reaction steps, namely, chain propagation reactions are supported by experiments.
- Ohtsuka, Naoya,Okuno, Moriaki,Hoshino, Yujiro,Honda, Kiyoshi
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supporting information
p. 9046 - 9054
(2016/10/05)
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- Racemization free longer N-terminal peptide hydroxamate synthesis on solid support using ethyl 2-(tert-butoxycarbonyloxyimino)-2-cyanoacetate
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A facile, efficient, racemization-free, and environment friendly protocol for the synthesis of peptide hydroxamic acids directly from carboxylic/amino acids by ethyl 2-(tert-butoxycarbonyloxyimino)-2-cyanoacetate in the presence of DIPEA/DMAP at room temperature is described. The compatibility of this method with Fmoc based solid phase peptide synthesis (SPPS) is also demonstrated by synthesizing three relatively large N-terminal peptide hydroxamic acids on resin. Also, some biologically important hydroxamates are synthesized using this protocol.
- Manne, Srinivasa Rao,Thalluri, Kishore,Giri, Rajat Subhra,Paul, Ashim,Mandal, Bhubaneswar
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supporting information
p. 6108 - 6111
(2015/10/28)
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- Amides and Ethers as Chemoselective Surrogates for Copper(II)-Catalyzed ortho Benzoyloxylation of 2-Phenylpyridines
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Chemoselective ortho benzoyloxylation of 2-phenylpyridine derivatives using amides and ethers as novel arylcarboxy sources using a Cu(II)/TBHP catalytic system has been reported. It is a simple protocol for ortho benzoyloxylation using amides and ethers as surrogates. A broad range of amides and ethers was found to be compatible under optimized reaction conditions to provide the corresponding products in good to excellent yield. The reaction proceeds through the cleavage of C-N, C-O, and C-H bonds and the formation of a new C-O bond via C-H functionalization.
- Yedage, Subhash L.,Bhanage, Bhalchandra M.
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supporting information
p. 2161 - 2169
(2015/09/15)
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- An Experimental and Computational Approach to Understanding the Reactions of Acyl Nitroso Compounds in [4 + 2] Cycloadditions
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Catalytic aerobic oxidation of phenyl hydroxycarbamate 1 and 1-hydroxy-3-phenylurea 2 using CuCl2 and 2-ethyl-2-oxazoline in methanol gave acyl nitroso species in situ, which were trapped in nitroso-Diels-Alder (NDA) reactions with various dienes to afford the corresponding cycloadducts in high yields (90-98%). Competing ene products were also present for dienes containing both alkene π-bonds and allylic σ-bonds, and the ene yields are higher with 1 than with 2. The use of the chiral hydroxamic acid, (R)-1-hydroxy-3-(1-phenylethylurea) 3 (same conditions) gave NDA cycloadducts in high yields (97-99%) with no ene product from 2,3-dimethyl-1,3-butadiene. NDA cycloadducts were not obtained from other hydroxamic acid analogues [RCONHOH (R = PhCH2 4; Ph(CH2)2 5; Ph(CH2)3 6; Ph(CH2)4 7; Ph 8; 2-pyridyl 9; 3-pyridyl 10] with various dienes using copper-oxidation but rather were obtained using sodium periodate, resulting in variable NDA yields (13-51%) from hydroxamic acids 1-10 with cyclohexa-1,3-diene and 2,3-dimethyl-1,3-butadiene (several cycloadducts characterized by X-ray crystallography). The NDA and nitroso-ene reaction pathways of nitroso intermediates with dienes were mapped by DFT computations (B3LYP/6-31G), which showed that the acyl nitroso species are super-reactive and that activation energies in the NDA processes are lower than the isomerization barriers between some cis- and trans-butadienes.
- Chaiyaveij, Duangduan,Batsanov, Andrei S.,Fox, Mark A.,Marder, Todd B.,Whiting, Andrew
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p. 9518 - 9534
(2015/10/12)
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- Ethyl 2-cyano-2-(4-nitrophenylsulfonyloxyimino)acetate-mediated lossen rearrangement: Single-pot racemization-free synthesis of hydroxamic acids and ureas from carboxylic acids
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Ethyl 2-cyano-2-(4-nitrophenylsulfonyloxyimino)acetate (4-NBsOXY) mediated Lossen rearrangement and its application for the synthesis of ureas is demonstrated. Required hydroxamic acids for the Lossen rearrangements were synthesized from carboxylic acids using the same reagent. Finally, reaction of an amine with the produced isocyanate resulted in urea. Good yields without racemization were achieved under milder and simpler reaction conditions. Reactions are compatible with common N-protecting groups, such as Boc, Fmoc, Cbz, and benzyl, as well as various OH protecting groups, such as tBu and Bzl. Conversion from carboxylic acid to urea is achieved in one pot. Most importantly, byproducts Oxyma [ethyl 2-cyano-2-(hydroxyimino)acetate] and 4-nitrobenzenesulfonic acid can be recovered easily and can be recycled to prepare the reagent. Thus, the method is environmentally friendly and cost-effective.
- Thalluri, Kishore,Manne, Srinivasa Rao,Dev, Dharm,Mandal, Bhubaneswar
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p. 3765 - 3775
(2014/05/20)
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- Rhodium-catalyzed C-H alkynylation of arenes at room temperature
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The rhodium(III)-catalyzed ortho C-H alkynylation of non-electronically activated arenes is disclosed. This process features a straightforward and highly effective protocol for the synthesis of functionalized alkynes and represents the first example of merging a hypervalent iodine reagent with rhodium(III) catalysis. Notably, this reaction proceeds at room temperature, tolerates a variety of functional groups, and more importantly, exhibits high selectivity for monoalkynylation. Hot rhod: A rhodium-catalyzed, electronically reversed Sonogashira reaction between unbiased arenes and the hypervalent iodine reagent 1 proceeds through C-H activation. This reaction displays excellent functional-group tolerance and high efficiency, and thus opens a new synthetic pathway to access functionalized alkynes. Cp=C5Me5, DCE=1,2-dichloroethane, Piv=pivaloyl, TIPS=triisopropylsilyl.
- Feng, Chao,Loh, Teck-Peng
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p. 2722 - 2726
(2014/03/21)
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- Rhodium(iii)-catalyzed formal oxidative [4 + 1] cycloaddition of benzohydroxamic acids and α-diazoesters. A facile synthesis of functionalized benzolactams
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A Rh(iii)-catalyzed oxidative [4 + 1] cycloaddition of benzohydroxamic acids and α-diazoesters is achieved to afford benzolactams in up to 93% yields. With the N-OAc amido moiety as a directing group, the ortho-C-H is selectively functionalized and the catalytic reaction exhibits excellent tolerance to different functional substituents. A notable rhodacyclic complex is isolated and structurally characterized, suggesting that C-H/N-H cyclometallation is a key step in the catalytic cycle. This journal is the Partner Organisations 2014.
- Lam, Hon-Wah,Man, Ka-Yi,Chan, Wai-Wing,Zhou, Zhongyuan,Yu, Wing-Yiu
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supporting information
p. 4112 - 4116
(2014/06/10)
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- One-pot synthesis of hydroxamic acids from aldehydes and hydroxylamine
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A one-pot oxidative transformation of aldehydes into hydroxamic acids by the use of an aqueous solution of hydroxylamine is reported. The methodology gives high yields and makes use of cheap, abundant and easily available reagents.
- Dettori, Giovanna,Gaspa, Silvia,Porcheddu, Andrea,De Luca, Lidia
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p. 2709 - 2713
(2014/09/17)
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- A two-step tandem reaction to prepare hydroxamic acids directly from alcohols
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The first synthesis of hydroxamic acids from alcohols has been developed. Both benzylic and aliphatic alcohols can be tolerated and applied in this reaction. The methodology is economical, environmentally benign and high yielding. This journal is
- Dettori, Giovanna,Gaspa, Silvia,Porcheddu, Andrea,De Luca, Lidia
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supporting information
p. 4582 - 4585
(2014/06/24)
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- An efficient method for the preparation of hydroxamic acids
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Reactions of acyl chlorides with hydroxylamine hydrochloride and NaHCO 3 generate the corresponding hydroxamic acid products in ethyl acetate and water at room temperature for 5 min. This is a simple and efficient method to synthesize a wide range of hydroxamic acids from carboxylic acids in excellent yield and high purity after simple post-treatment without chromatographic purification. In this process, the highlights are the simple separation of products and cheaply available reagents.
- Gao, Xi-Ai,Wang, Xian-Xue,Yan, Hao,Li, Jian,Yan, Ru-Long,Huang, Guo-Sheng
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p. 381 - 385
(2013/05/22)
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- Production of hydroxamic acids by immobilized Pseudomonas aeruginosa cells: Kinetic analysis in reverse micelles
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Intact cells from Pseudomonas aeruginosa strain L10 containing amidase were used as biocatalysts both free and immobilized in a reverse micellar system. The apparent kinetic constants for the transamidation reaction in hydroxamic acids synthesis, were determined using substrates such as aliphatic, amino acid and aromatic amides and esters, in both media. In reverse micelles, K m values decreased 2-7 fold relatively to the free biocatalyst using as substrates acetamide, acrylamide, propionamide and glycinamide ethyl ester. We have concluded that overall the affinity of the biocatalyst to each substrate increases when reactions are performed in the reversed micellar system as opposed to the buffer system. The immobilized biocatalyst in general, exhibits higher stability and faster rates of reactions at lower substrates concentration relatively to the free form, which is advantageous. Additionally, the immobilization revealed to be suitable for obtaining the highest yields of hydroxamic acids derivatives, in some cases higher than 80%.
- Bernardo, Marisa,Pacheco, Rita,Serralheiro, Maria Luisa M.,Karmali, Amin
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