- Transketolase Catalyzed Synthesis of N-Aryl Hydroxamic Acids
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Hydroxamic acids are metal-chelating compounds that show important biological activity including anti-tumor effects. We have recently engineered the transketolase from Geobacillus stearothermopilus (TKgst) to convert benzaldehyde as a non-natur
- Fúster Fernández, Inés,Hecquet, Laurence,Fessner, Wolf-Dieter
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p. 612 - 621
(2021/12/08)
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- The silver-mediated annulation of arylcarbamic acids and nitrosoarenes toward phenazines
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A silver-mediated annulation between arylcarbamic acids and nitrosoarenes was developed, leading to phenazines in moderate to good yields with complexity and diversity. This procedure proceeded with the sequential ortho[sbnd] C[sbnd]H functionalization of arylcarbamic acids, insertion to nitroso group and decarboxylative annulation.
- Chen, Fan,Cheng, Jiang,Qian, Peng-Cheng,Wang, Lu
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supporting information
(2021/12/17)
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- Nitrosobenzene-Enabled Chiral Phosphoric Acid Catalyzed Enantioselective Construction of Atropisomeric N-Arylbenzimidazoles
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Described herein is an imidazole ring formation strategy for the synthesis of axially chiral N-arylbenzimidazoles by means of chiral phosphoric acid catalysis. Two sets of conditions were developed to transform two classes of 2-naphthylamine derivatives into structurally diverse N-arylbenzimidazole atropisomers with excellent chemo- and regioselectivity as well as high levels of enantiocontrol. It is worth reflecting on the unique roles played by the nitroso group in this domino reaction. It functions as a linchpin by first offering an electrophilic site (N) for the initial C?N bond formation while the resulting amine performs the nucleophilic addition to form the second C?N bond. Additionally, it could facilitate the final oxidative aromatization as an oxidant. The atropisomeric products could be conveniently elaborated to a series of axially chiral derivatives, enabling the exploitation of N-arylbenzimidazoles for their potential utilities in asymmetric catalysis.
- An, Qian-Jin,Xia, Wang,Ding, Wei-Yi,Liu, Huan-Huan,Xiang, Shao-Hua,Wang, Yong-Bin,Zhong, Guofu,Tan, Bin
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supporting information
p. 24888 - 24893
(2021/10/20)
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- A Photoswitchable Agonist for the Histamine H3 Receptor, a Prototypic Family A G-Protein-Coupled Receptor
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Spatiotemporal control over biochemical signaling processes involving G protein-coupled receptors (GPCRs) is highly desired for dissecting their complex intracellular signaling. We developed sixteen photoswitchable ligands for the human histamine H3 receptor (hH3R). Upon illumination, key compound 65 decreases its affinity for the hH3R by 8.5-fold and its potency in hH3R-mediated Gi protein activation by over 20-fold, with the trans and cis isomer both acting as full agonist. In real-time two-electrode voltage clamp experiments in Xenopus oocytes, 65 shows rapid light-induced modulation of hH3R activity. Ligand 65 shows good binding selectivity amongst the histamine receptor subfamily and has good photolytic stability. In all, 65 (VUF15000) is the first photoswitchable GPCR agonist confirmed to be modulated through its affinity and potency upon photoswitching while maintaining its intrinsic activity, rendering it a new chemical biology tool for spatiotemporal control of GPCR activation.
- Hauwert, Niels J.,Mocking, Tamara A. M.,Da Costa Pereira, Daniel,Lion, Ken,Huppelschoten, Yara,Vischer, Henry F.,De Esch, Iwan J. P.,Wijtmans, Maikel,Leurs, Rob
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supporting information
p. 4531 - 4535
(2019/03/07)
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- Enantioselective Oxidative Coupling of β-Ketocarbonyls and Anilines by Joint Chiral Primary Amine and Selenium Catalysis
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An enantioselective primary amine-catalyzed total N-selective nitroso aldol reaction (N-NA) was achieved through the oxidation of primary aromatic amines to the corresponding nitrosoarenes catalyzed by selenium reagents and 30% H2O2. This protocol provides a facile and highly efficient access to α-hydroxyamino carbonyls bearing chiral quaternary centers under exceedingly mild and green reaction conditions with high chemo-and enantiocontrol.
- Chen, Wanting,Wang, Yanni,Mi, Xueling,Luo, Sanzhong
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supporting information
p. 8178 - 8182
(2019/10/16)
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- A toolbox of molecular photoswitches to modulate the CXCR3 chemokine receptor with light
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We report a detailed structure–activity relationship for the scaffold of VUF16216, a compound we have previously communicated as a small-molecule efficacy photoswitch for the peptidergic chemokine GPCR CXCR3. A series of photoswitchable azobenzene ligands was prepared through various synthetic strategies and multistep syntheses. Photochemical and pharmacological properties were used to guide the design iterations. Investigations of positional and substituent effects reveal that halogen substituents on the ortho-position of the outer ring are preferred for conferring partial agonism on the cis form of the ligands. This effect could be expanded by an electron-donating group on the para-position of the central ring. A variety of efficacy differences between the trans and cis forms emerges from these compounds. Tool compounds VUF15888 (4d) and VUF16620 (6e) represent more subtle efficacy switches, while VUF16216 (6f) displays the largest efficacy switch, from antagonism to full agonism. The compound class disclosed here can aid in new photopharmacology studies of CXCR3 signaling.
- Gómez-Santacana, Xavier,De Munnik, Sabrina M.,Mocking, Tamara A.M.,Hauwert, Niels J.,Sun, Shanliang,Vijayachandran, Prashanna,De Esch, Iwan J.P.,Vischer, Henry F.,Wijtmans, Maikel,Leurs, Rob
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supporting information
p. 2509 - 2523
(2019/12/11)
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- Synthesis of Di(hetero)arylamines from Nitrosoarenes and Boronic Acids: A General, Mild, and Transition-Metal-Free Coupling
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The synthesis of di(hetero)arylamines by a transition-metal-free cross-coupling between nitrosoarenes and boronic acids is reported. The procedure is experimentally simple, fast, mild, and scalable and has a wide functional group tolerance, including carbonyls, nitro, halogens, free OH and NH groups. It also permits the synthesis of sterically hindered compounds.
- Roscales, Silvia,Csák?, Aurelio G.
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supporting information
p. 1667 - 1671
(2018/03/23)
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- Metal-Free Sequential C(sp2)-H/OH and C(sp3)-H Aminations of Nitrosoarenes and N-Heterocycles to Ring-Fused Imidazoles
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Hydrogen bond assisted ortho-selective C(sp2)-H amination of nitrosoarenes and subsequent α-C(sp3)-H functionalization of aliphatic amines is achieved under metal-free conditions. The annulation of nitrosoarenes and 2-hydroxy-C-nitroso compounds with N-heterocycles provides a facile excess to a wide range of biologically relevant ring-fused benzimidazoles and structurally novel polycyclic imidazoles, respectively. Nucleophilic aromatic hydrogen substitution (SNArH) was found to be preferred over classical SNAr reaction during the C(sp2)-H amination of halogenated nitrosoarenes.
- Purkait, Anisha,Roy, Subhra Kanti,Srivastava, Hemant Kumar,Jana, Chandan K.
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supporting information
p. 2540 - 2543
(2017/05/24)
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- The effect of water on the hydrogenation of o-chloronitrobenzene in ethanol, n-heptane and compressed carbon dioxide
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Water as a clean solvent and promoter in the organic synthesis have attracted more attention, herein the effect of water was studied for the hydrogenation of o-chloronitrobenzene (o-CNB) over Pt/C and Pd/C catalysts in ethanol, n-heptane and compressed CO2. Very interesting, the reaction rate decreased in ethanol, but increased in n-heptane and compressed CO 2 with the addition of water. The role of water in the reaction was mainly discussed from the experimental data and phase behavior analysis, one is to activate the functional group of NO2 through the interactions via a hydrogen bonding, and the other is to affect the solubility of hydrogen in ethanol and n-heptane. The positive effect of the interaction between water and reactants may be counteracted by the negative effect of hydrogen solubility in ethanol. However, the concentration of o-CNB and hydrogen changed slightly in n-heptane with the addition of water, so the interaction of water with reactants may play a main role in improving the TOF. The combination of H2O and CO2 is more efficient than the pure H2O, CO 2 and H2O-n-heptane systems. The phase behavior may play important role also for the improved activity except for the interactions of H2O and CO2 with the reactants. o-CNB phase was expanded in the compressed CO2 and so the concentration of H2 in o-CNB phase increased due to the miscible of CO2 and H2, resulting in the enhancement of reaction rate and the maximum conversion at pressure of 9 MPa CO2, at which the volume was expanded to the largest one. The similar results were also obtained in the compressed CO 2 system without H2O. In addition, the stability of Pt/C and Pd/C was studied in H2O-n-heptane and H2O-CO 2. As a result, the H2O-CO2 media and Pt/C catalyst is one of the most effective systems for the hydrogenation of o-CNB.
- Cheng, Haiyang,Meng, Xiangchun,Yu, Yancun,Zhao, Fengyu
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- Synthesis and structural, spectroscopic, and electrochemical characterization of benzo[c]quinolizinium and its 5-aza-, 6-aza, and 5,6-diaza analogues
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Four heterocyclic salts 1a-d were prepared by Ca2+-assisted cyclization of fluoro derivatives 3, and investigated by spectroscopic (NMR and UV), electrochemical, and computational (DFT and MP2) methods. The mechanism for the formation of the ca
- Jankowiak, Aleksandra,Obijalska, Emilia,Kaszynski, Piotr,Pieczonka, Adam,Young Jr., Victor G.
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experimental part
p. 3317 - 3327
(2011/06/17)
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- Selective hydrogenation of chloronitrobenzene to chloroaniline in supercritical carbon dioxide over Ni/TiO2: Significance of molecular interactions
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The hydrogenation of chloronitrobenzene to chloroaniline was investigated over Ni/TiO2 at 35 °C in supercritical CO2 (scCO2), ethanol, and n-hexane. The reaction rate followed the order of scCO2 > n-hexane > eth
- Meng, Xiangchun,Cheng, Haiyang,Fujita, Shin-ichiro,Hao, Yufen,Shang, Yanjiao,Yu, Yancun,Cai, Shuxia,Zhao, Fengyu,Arai, Masahiko
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scheme or table
p. 131 - 139
(2010/09/17)
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- Selective N-oxidation of aromatic amines to nitroso derivatives using a molybdenum acetylide oxo-peroxo complex as catalyst
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The molybdenum acetylide oxo-peroxo complex obtained in situ by the treatment of the corresponding molybdenum acetylide carbonyl complex, CpMo(CO)3(C{triple bond, long}CPh); Cp = η5-C5H5 with H2O2, has been used as an efficient catalyst for selective N-oxidation of primary amines to nitroso derivatives. Excellent amine conversion (up to 100%) and very high selectivity for nitroso compounds (99%) have been obtained using 30% hydrogen peroxide as an oxidant. The oxo peroxo Mo(VI) complex has also been found to be very active for the oxidation of various substituted primary aromatic amines with electron donating as well as electron withdrawing substituents on the aromatic ring.
- Biradar, Ankush V.,Kotbagi, Trupti V.,Dongare, Mohan K.,Umbarkar, Shubhangi B.
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p. 3616 - 3619
(2008/09/19)
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- Tungsten- and molybdenum-based coordination polymer-catalyzed N-oxidation of primary aromatic amines with aqueous hydrogen peroxide
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Recyclable tungsten- and molybdenum-based coordination polymers efficiently catalyzed the oxidation of primary aromatic amines to the corresponding nitroso derivatives with 30% aqueous hydrogen peroxide in high yields at room temperature.
- Bordoloi, Ankur,Halligudi
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p. 2085 - 2088
(2008/09/18)
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- Reactions of nitrosoarenes containing electron-withdrawing substituents with coordinated CO. Synthesis and structure of complexes Pd2(OAc) 2(p-ClC6H4N[p-ClC6H 3NO])2 and Pd2(OAc)2(o-ClC 6H4N[o-ClC6H3NO])2
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The reaction of tetranuclear Pd4(μ-COOCH3) 4(μ-CO)4 cluster (1a) with p- and o- chloronitrosobenzenes was found to give dinuclear nitrosoamide complexes, Pd2(OAc)2(p-ClC6H4N[p-ClC 6H3NO])2 (4) and Pd2(OAc) 2(o-ClC6H4N[o-ClC6H 3NO])2 (5), respectively. The formation of complexes 4 and 5 is accompanied by evolution of CO2, resulting from oxidation of CO coordinated in cluster 1. Complexes 4 and 5 were characterized by elemental analysis and IR and 1H NMR spectroscopy; their structures were studied by EXAFS. The reactions of dinuclear complex 4 with molecular hydrogen and CO were studied. The major products of reduction of 4 with hydrogen include metallic palladium, acetic acid, cyclohexanone, and molecular nitrogen. Treatment of complex 4 with CO under mild conditions (1 atm, 20°C) affords p-chlorophenyl isocyanate.
- Orlova,Stromnova,Kazyul'kin,Boganova,Kochubey,Novgorodov
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p. 819 - 824
(2007/10/03)
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- Reaction of dimethyldioxirane with aniline hydrohalides
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Oxidation of aromatic amine hydrohalides (aniline hydrochloride, hydrobromide, and hydrofluoride; 4-methylaniline hydrochloride and hydrobromide; 3-methylaniline and N,N-diethylaniline hydrochlorides) with dimethyldioxirane was studied. The product composition was analyzed in relation to the reactant ratio.
- Ivanova,Grabovskii,Kabal'nova,Shereshovets
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p. 2101 - 2105
(2007/10/03)
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- Oxidation of Primary Aromatic Amines, Catalyzed by Tungsten Compounds
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Treatment of o-nitroanilines and o-aminobenzoic acids with 30 percent hydrogen peroxide in the presence of Na2WO4 and H3PO4 results in selective formation of corresponding nitroso derivatives.In other cases, the products are azoxy compounds.Oxidation of anilines containing alkyl or alkoxy groups in the ortho and para positions with hydrogen peroxide in the presence of Na2WO4 and tetrabutylammonium bromide quantitatively yields corresponding nitrosobenzenes.The H2O2-Na2WO4-H3PO4 system in the presence of tetrabutylammonium bromide is proposed for preparation of nitroso derivatives from anilines containing electron-acceptor meta and para substituents.
- Mel'nikov, E. B.,Suboch, G. A.,Belyaev, E. Yu.
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p. 1640 - 1642
(2007/10/03)
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- Reaction of 6-Ethylamino-3-methyluracil with Nitrobenzenes
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Reaction of 6-ethylamino-3-methyluracil (1) with nitrobenzenes in hexamethylphosphoric triamide gave isoalloxazines in 3.8-18 percent yield.In the presence of potassium carbonate, reaction of 1 with o-fluoronitrobenzene afforded 5-substituted uracil 3 in moderate yield.
- Harayama, Takashi,Jinno, Hideto,Tezuka, Yasuhiro,Yoneda, Fumio
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p. 1507 - 1509
(2007/10/02)
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