- Polystyrene stabilized iridium nanoparticles catalyzed chemo- and regio-selective semi-hydrogenation of nitroarenes to N-arylhydroxylamines
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Polystyrene stabilized Iridium (Ir@PS) nanoparticles (NPs) as a heterogeneous catalyst have been developed and characterized by IR, UV–Vis, SEM, TEM, EDX and XRD studies. The prepared Ir@PS catalyst showed excellent reactivity for chemo- and regio-selective controlled-hydrogenation of functionalized nitroarenes to corresponding N-arylhydroxylamine using hydrazine hydrate as reducing source and environmentally benign polyethylene glycol (PEG-400) as green solvent. The present methodology was applied for vast substrate scope and found to be compatible with wide range of reducible functional groups. The reaction performed at 85 °C or ambient temperature and completed within 5–80 minutes. The catalyst can easily be filtered out from reaction mixture and reusable.
- Bhattacherjee, Dhananjay,Das, Pralay,Kumar, Ajay,Shaifali,Zyryanov, Grigory V.
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- Redox-Neutral Selenium-Catalysed Isomerisation of para-Hydroxamic Acids into para-Aminophenols
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A selenium-catalysed para-hydroxylation of N-aryl-hydroxamic acids is reported. Mechanistically, the reaction comprises an N?O bond cleavage and consecutive selenium-induced [2,3]-rearrangement to deliver para-hydroxyaniline derivatives. The mechanism is studied through both 18O-crossover experiments as well as quantum chemical calculations. This redox-neutral transformation provides an unconventional synthetic approach to para-aminophenols.
- Chuang, Hsiang-Yu,Schupp, Manuel,Meyrelles, Ricardo,Maryasin, Boris,Maulide, Nuno
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supporting information
p. 13778 - 13782
(2021/03/31)
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- Selective Photoinduced Reduction of Nitroarenes to N-Arylhydroxylamines
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We report the selective photoinduced reduction of nitroarenes to N-arylhydroxylamines. The present methodology facilitates this transformation in the absence of catalyst or additives and uses only light and methylhydrazine. This noncatalytic photoinduced transformation proceeds with a broad scope, excellent functional-group tolerance, and high yields. The potential of this protocol reflects on the selective and straightforward conversion of two general antibiotics, azomycin and chloramphenicol, to the bioactive hydroxylamine species.
- Kallitsakis, Michael G.,Ioannou, Dimitris I.,Terzidis, Michael A.,Kostakis, George E.,Lykakis, Ioannis N.
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supporting information
p. 4339 - 4343
(2020/06/08)
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- Regioselective installation of fluorosulfate (-OSO2F) functionality into aromatic C(sp2)-H bonds for the construction of: Para-amino-arylfluorosulfates
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The construction of para-amino-arylfluorosulfates was achieved through installation of fluorosulfate (-OSO2F) functionality into aromatic C(sp2)-H bonds by the reaction of N-arylhydroxylamine with sulfuryl fluoride (SO2Fs
- Fang, Wan-Yin,Zha, Gao-Feng,Zhao, Chuang,Qin, Hua-Li
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supporting information
p. 6273 - 6276
(2019/06/07)
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- A Modified System for the Synthesis of Enantioenriched N-Arylamines through Copper-Catalyzed Hydroamination
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Despite significant recent progress in copper-catalyzed enantioselective hydroamination chemistry, the synthesis of chiral N-arylamines, which are frequently found in natural products and pharmaceuticals, has not been realized. Initial experiments with N-arylhydroxylamine ester electrophiles were unsuccessful and, instead, their reduction in the presence of copper hydride (CuH) catalysts was observed. Herein, we report key modifications to our previously reported hydroamination methods that lead to broadly applicable conditions for the enantioselective net addition of secondary anilines across the double bond of styrenes, 1,1-disubstituted olefins, and terminal alkenes. NMR studies suggest that suppression of the undesired reduction pathway is the basis for the dramatic improvements in yield under the reported method.
- Ichikawa, Saki,Zhu, Shaolin,Buchwald, Stephen L.
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supporting information
p. 8714 - 8718
(2018/07/14)
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- Trifluoromethyl Vinyl Sulfide: A Building Block for the Synthesis of CF3S-Containing Isoxazolidines
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Trifluoromethyl vinyl sulfide, a potential building block for pharmaceutically and agrochemically relevant products, is prepared and used for the first time in high-pressure-mediated 1,3-dipolar cycloaddition reactions with nitrones to synthesize (trifluoromethyl)sulfanyl isoxazolidines.
- Riesco-Domínguez, Alejandra,Van De Wiel, Jeroen,Hamlin, Trevor A.,Van Beek, Bas,Lindell, Stephen D.,Blanco-Ania, Daniel,Bickelhaupt, F. Matthias,Rutjes, Floris P. J. T.
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p. 1779 - 1789
(2018/02/23)
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- TRIFLUOROMETHOXYLATION OF ARENES VIA INTRAMOLECULAR TRIFLUOROMETHOXY GROUP MIGRATION
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The present invention provides a process of producing a trifluoromethoxylated aryl or trifluoromethoxylated heteroaryl having the structure: (I), wherein A is an aryl or heteroaryl, each with or without subsutitution; and R1 is -H, -(alkyl), -(alkenyl), -(alkynyl), -(aryl), -(heteroaryl), - (alkylaryl), - (alkylheteroaryl), -NH-(alkyl), -N(alkyl)2, -NH-(alkenyl), -NH-(alkynyl) -NH-(aryl), -NH-(heteroaryl), -O-(alkyl), -O-(alkenyl), -O-(alkynyl), -O-(aryl), -O-(heteroaryl), -S-(alkyl), -S- (alkenyl), -S-(alkynyl), -S-(aryl), or -S-(heteroaryl), comprising: (a) reacting a compound having the structure: (II), with a trifluoromethylating agent in the presence of a base in a first suitable solvent under conditions to produce a compound having the structure: (III); and (b) maintaining the compound produced in step (a) in a second suitable solvent under conditions sufficient to produce the trifluoromethoxylated aryl or trifluormethoxylated heteroaryl having the structure: (I).
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Page/Page column 62
(2016/05/02)
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- Mechanistic studies on intramolecular C-H trifluoromethoxylation of (hetero)arenes via OCF3-migration
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The one-pot two-step intramolecular aryl and heteroaryl C-H trifluoromethoxylation recently reported by our group has provided a general, scalable, and operationally simple approach to access a wide range of unprecedented and valuable OCF3-containing building blocks. Herein we describe our investigations to elucidate its reaction mechanism. Experimental data indicate that the O-trifluoromethylation of N-(hetero)aryl-N-hydroxylamine derivatives is a radical process, whereas the OCF3-migration step proceeds via a heterolytic cleavage of the N-OCF3 bond followed by rapid recombination of a short-lived ion pair. Computational studies further support the proposed ion pair reaction pathway for the OCF3-migration process. We hope that the current study would provide useful insights for the development of new transformations using versatile N-(hetero)aryl-N-hydroxylamine synthons.
- Lee, Katarzyna N.,Lei, Zhen,Morales-Rivera, Cristian A.,Liu, Peng,Ngai, Ming-Yu
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supporting information
p. 5599 - 5605
(2016/07/06)
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- Trifluoromethoxylation of arenes: Synthesis of ortho- Trifluoromethoxylated aniline derivatives by OCF3 migration
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Aryl trifluoromethoxylation by a two-step sequence of O-trifluoromethylation of N-aryl-N-hydroxylamine derivatives and intramolecular OCF3 migration is presented. This protocol allows easy access to a wide range of synthetically useful ortho-OCF3 aniline derivatives. In addition, it utilizes bench-stable reagents, is operationally simple, shows high functional-group tolerance, and is amenable to gram-scale as well as one-pot synthesis.Areaction mechanism of a heterolytic cleavage of the N-OCF3 bond followed by recombination of the resulting nitrenium ion and trifluoromethoxide is proposed for the OCF3-migration reaction.
- Hojczyk, Katarzyna N.,Feng, Pengju,Zhan, Chengbo,Ngai, Ming-Yu
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supporting information
p. 14559 - 14563
(2015/01/09)
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- Solid supported platinum(0) nanoparticles catalyzed chemo-selective reduction of nitroarenes to N-arylhydroxylamines
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Solid supported platinum(0) (SS-Pt) nanoparticles were developed as a heterogeneous catalyst following a reduction/deposition method and characterized by SEM, TEM, EDX and XRD analysis. The SS-Pt catalyst was applied in the chemo-selective reduction of nitroarenes to N-arylhydroxylamines using hydrazine hydrate as a hydrogen source. A wide variety of reducible functional groups such as halides, carboxylic acids, esters, amides, nitriles, keto, alkenes, alkynes and N-benzyl were well tolerated under the reaction conditions. This process was further successfully employed in 10 g scale reactions. N-Arylhydroxylamines were further applied for catalyst free synthesis of azoxybenzenes. Moreover, use of PEG-400 as cheap reaction medium, additive free methodology and the recyclability of SS-Pt catalyst up to ten times without significant loss of catalytic activity evidently follow the principles of green chemistry.
- Shil, Arun K.,Das, Pralay
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supporting information
p. 3421 - 3428
(2013/12/04)
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- Synthesis and reactivity of N-hydroxy-2-aminoindoles
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Catalytic hydrogenation of (2-nitrophenyl)acetonitriles bearing an electron-withdrawing substituent α to the nitrile, using Pd/C and (Ph 3P)4Pd, affords N-hydroxy-2-aminoindoles in good to excellent yields. (Ph3P)4Pd decreases the reduction rate of the intermediate hydroxylamine and acts as a catalyst during the cyclization onto the nitrile.
- Belley, Michel,Sauer, Effiette,Beaudoin, Daniel,Duspara, Petar,Trimble, Laird A.,Dubé, Pascal
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p. 159 - 162
(2007/10/03)
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- Ultrasonically activated reduction of substituted nitrobenzenes to corresponding N-arylhydroxylamines
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Arylhydroxylamines can be obtained by reduction of the corresponding nitroaromatic compounds. We report here an efficient preparation of arylhydroxylamines by a controlled reduction of nitro compounds using zinc metal and ammonium chloride under ultrasonic activation in very short reaction times.
- Ung, Stéphane,Falguières, Annie,Guy, Alain,Ferroud, Clotilde
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p. 5913 - 5917
(2007/10/03)
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- Herbicidally active phenylsubstituted 5-and 6-membered heterocyclic compounds
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A compound of formula (I): STR1 where E is oxygen or sulphur; A is CR3 or N where R3 is hydrogen or hydrocarbyl; D completes a 5 or 6-membered non-aromatic heterocyclic ring which optionally contains additional heteroatoms selected from oxygen, nitrogen or sulphur and which is optionally substituted by an optionally substituted lower hydrocarbyl group, or an optionally substituted heteroaryl group; R1 and R2 are each independently hydrogen; optionally substituted lower hydrocarbyl, or optionally substituted heteroaryl, or R1 and R2 together with the nitrogen atom to which they are attached, form a heterocyclic ring; Z represents halogen optionally substituted lower hydrocarbyl, optionally substituted lower hydocarbyloxy, optionally substituted lower hydrocarbylthio, hydrocarbylsulphinyl or hydrocarbylsulphonyl, cyano, nitro, CHO, NHOH, ONR7' R7", SF5 ; CO (optionally substituted lower hydrocarbyl), acylamino, COOR7, SO2 NR8 R9, CONR10 R11, OR12 or NR13 R14 where R7, R7', R7", R8, R9, R10 and R11 are independently hydrogen or lower hydrocarbyl; R12 is hydrogen; SO2 lower hydrocarbyl or COR15 ; R13 and R14 are independently lower hydrocarbyl, lower hydrocarbyloxy or a group R12 ; R15 is OR16, NR17 R18, hydrogen or lower hydrocarbyl; R16 is lower hydrocarbyl; R17 and R18 are independently hydrogen or lower hydrocarbyl; provided that when there are two or more substituents Z, they may be the same or different; and m is 0 or an integer from 1 to 5.
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- Metal Ion-Catalyzed Reduction of Substituted Nitrosobenzenes by 1-Benzyl-3,5-bis(1-pyrrolidinylcarbonyl)-1,4-dihydropyridine in Acetonitrile
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Metal ion catalyzed reduction of substituted nitrosobenzenes by 1-benzyl-3,5-bis(1-pyrrolidinylcarbonyl)-1,4-dihydropyridine (BPDH) in acetonitrile has been studied for seven bivalent metal ions.The reduction of N-methylacridinium salt (MA) has also been examined.In the former cases, it was found that the metal ions catalyze the reduction by forming a 1 : 1 complex with BPDH according to a Michaelis-Menten type saturation kinetics which allowed to derive the association constants, KM, for the complexation and the second-order rate constants, k2, for the reduction.A linear relationship was found between log k2 and the ionization potentials of metal ions with a positive slope.A linear Hammett relationship was also observed between log k2 and the Hammett ? constants with a positive p value for three metal ions.These results suggest that a bivalent metal ion is sandwiched between the BPDH and the substrate and acts as a Lewis acid to stabilize the incipient N-oxide anion of the substrate which is formed by hydride transfer in the transition state.In the cases of MA, all metal ions inhibited the reduction.Repulsion between the positive charges of the metal ion-BPDH complex and the substrate salt appears to be prevailing.
- Awano, Hiroshi,Takemoto, Kazuo,Ohya, Hirohisa,Tomio, Minaki,Tamagaki, Seizo,Tagaki, Waichiro
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p. 1887 - 1894
(2007/10/02)
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