- Tosylamidation of Cyclohexane by a Cytochrome P-450 Model
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Reaction of cyclohexane with (tosyliminoiodo)benzene and manganese(III)- or iron(III)-tetraphenylporphyrin chloride affords N-cyclohexyltoluene-p-sulphonamide.
- Breslow, Ronald,Gellman, Samuel H.
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- Au(I)-Catalyzed Oxidative Functionalization of Yndiamides
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Yndiamides, underexplored cousins of ynamides, offer rich synthetic potential as doubly nitrogenated two carbon building blocks. Here we report a gold-catalyzed oxidative functionalization of yndiamides to access unnatural amino acid derivatives, using a wide range of nucleophiles as a source of the amino acid side chain. The transformation proceeds under mild conditions, is highly functional group tolerant, and displays excellent regioselectivity through subtle steric differentiation of the yndiamide nitrogen atom substituents.
- Tong, Zixuan,Garry, Olivia L.,Smith, Philip J.,Jiang, Yubo,Mansfield, Steven J.,Anderson, Edward A.
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supporting information
p. 4888 - 4892
(2021/06/28)
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- Direct Synthesis of α-Amino Nitriles from Sulfonamides via Base-Mediated C-H Cyanation
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Herein, we disclose a transition-metal-free reaction system that enables α-cyanation of sulfonamides through C-H bond cleavage for the preparation of α-amino nitriles, including difficult-to-access all-alkyl α-tertiary scaffolds. More than 50 substrate examples prove a wide functional group tolerance. Additionally, its synthetic practicality is highlighted by gram-scalability and the late-stage modification of natural compounds. Mechanistic experiments suggest that this process involves in situ formation of an imine intermediate via base-promoted elimination of HF.
- Shi, Shasha,Yang, Xianyu,Tang, Man,Hu, Jiefeng,Loh, Teck-Peng
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p. 4018 - 4022
(2021/05/26)
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- Nickel/Photoredox Dual Catalytic Cross-Coupling of Alkyl and Amidyl Radicals to Construct C(sp3)-N Bonds
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The construction of C(sp3)-N bonds via direct radical-radical cross-coupling under benign conditions is a desirable but challenging approach. Herein, the cross-coupling of alkyl and amidyl radicals to build aliphatic C-N bonds in a concise, mild, and oxid
- Zhou, Shaofang,Lv, Kang,Fu, Rui,Zhu, Changlei,Bao, Xiaoguang
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p. 5026 - 5034
(2021/05/07)
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- A new generation of terminal copper nitrenes and their application in aromatic C-H amination reactions
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Copper nitrene complexes are highly reactive species and are known as intermediates in the copper catalyzed C-H amination. In this study, three novel copper tosyl nitrene complexes were synthesized at low temperatures, stabilized with heteroscorpionate ligands of the bis(pyrazolyl)methane family. The copper nitrenes were obtained by the reaction of a copper(i) acetonitrile complex with SPhINTs in dichloromethane. We show that the ligand design has a major influence on the catalytic activity and the thermal stability of the copper nitrene complex. Not only the choice of the third N donor, but also the substituent in the 5-position of the pyrazolyl moiety, have an impact on the stability. Furthermore, the novel copper nitrene complexes were used for catalytic aziridination of styrenes and C-H amination reactions of aromatic and aliphatic substrates under mild reaction conditions. Even challenging substrates like benzene and cyclohexane were aminated with good yields. The copper nitrene complexes were characterized using UV/Vis spectroscopy, low temperature Evans NMR spectroscopy, density functional theory, domain-based local pair natural orbital coupled cluster calculations (DLPNO-CCSD(T)) and cryo-UHR mass spectrometry.
- Amarouch, Benedikt,G?bgen, Kai C.,Hoffmann, Alexander,Oster, Matthias,Sch?n, Florian,Steden, Dominik,Thomas, Fabian
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supporting information
p. 6444 - 6462
(2021/05/26)
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- Chiral bis(pyrazolyl)methane copper(I) complexes and their application in nitrene transfer reactions
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In this study, chiral bis(pyrazolyl)methane copper(I) acetonitrile complexes were applied to generate two novel terminal copper tosyl nitrene complexes with the nitrene generating agent SPhINTs in dichloromethane at low temperatures. The syntheses of the chiral bis(pyrazolyl)methane ligands are based on pulegone and camphor, members of the natural chiral pool. The chiral copper(I) acetonitrile complexes were applied as catalysts in the copper nitrene mediated aziridination reaction of different styrene derivatives and the C-H amination of various substrates. The reactions afforded good yields, but low enantiomeric excess under mild conditions. The nitrene species have been characterized with UV/Vis and EPR spectroscopy and the products of the decay by ESI mass spectrometry.
- Thomas, Fabian,Steden, Dominik,Eith, Alexander,Hoffmann, Alexander,Herres-Pawlis, Sonja
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p. 835 - 847
(2021/11/09)
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- Metal-free C-H Activation over Graphene Oxide toward Direct Syntheses of Structurally Different Amines and Amides in Water
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Unprecedented metal-free synthesis of a variety of amines and amides is reported via amination of C(sp3)-H and C(sp2)-H bonds. The strategy involves graphene-oxide/I2-catalyzed nitrene insertion using PhINTs as a nitrene (NT) source in water at room temperature. A wide range of structurally different substrates, viz., cyclohexane, cyclic ethers, arenes, alkyl aromatic systems, and aldehydes/ketones, having an α-phenyl ring have been employed successfully to afford the corresponding nitrene insertion product in good yield, albeit low in few cases. The envisaged method has superiority over others in terms of its operational simplicity, metal-free catalysis, use of water as a solvent, ambient reaction conditions, and reusability of the catalyst.
- Shukla, Prashant,Asati, Ambika,Bhardiya, Smita R.,Singh, Manorama,Rai, Vijai K.,Rai, Ankita
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p. 15552 - 15561
(2020/12/02)
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- KCC-1 aminopropyl-functionalized supported on iron oxide magnetic nanoparticles as a novel magnetic nanocatalyst for the green and efficient synthesis of sulfonamide derivatives
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A new magnetic nanocatalyst (Fe3O4@KCC-1-npr-NH2) was synthesized directly through the reaction of Fe3O4@KCC-1 with (3-aminopropyl) triethoxysilane (APTES) using a hydrothermal protocol. Prepared nanocomposite was used as a magnetically reusable nanocatalyst for an efficient synthesis of a broad range of sulfonamide derivatives in water as a green solvent at room temperature and the products are collected by filtration with excellent yields (85–97%). The nanocatalyst could be remarkably recovered and reused after ten times without any significant decrease in activity. This mild and simple synthesis method offers some advantages including short reaction time, high yield and simple work-up procedure.
- Azizi, Sajjad,Shadjou, Nasrin,Hasanzadeh, Mohammad
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- Copper iodide nanoparticles-decorated porous polysulfonamide gel: As effective catalyst for decarboxylative synthesis of N-Arylsulfonamides
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A porous cross-linked poly (ethyleneamine)-polysulfonamide (PEA-PSA) as a novel organic support system is synthesized in the presence of silica template by nanocasting technique. The paper demonstrates immobilization of CuI nanoparticles inside the pores (PEA-PSA?CuI) for the facile recovery and recycling of these nanoparticles. The presence of porous PEA-PSA and PEA-PSA?CuI nanocomposites was confirmed using FT-IR spectroscopy, FE-SEM, EDX, TGA, XRD, TEM, BET, XPS, WDX, 1H NMR, and ICP-OES techniques. The PEA-PSA?CuI along with Ag(I)/K2S2O8 was implemented as a reusable cooperative catalyst-oxidant system in the N-arylation of p-toluenesulfonamide with substituted carboxylic acids in mild condition. So, the novel decarboxylative cross-coupling catalyzed by copper and silver has been developed. Aromatic, secondary and tertiary aliphatic acids underwent high efficient decarboxylative processes with p-toluenesulfonamide to afford the corresponding products. This method provides a practical approach for the flexible synthesis of sulfonamides from the readily affordable substrates. The catalyst is highly reusable and efficient, especially in terms of time and yield of the desired product.
- Alavinia, Sedigheh,Ghorbani-Vaghei, Ramin,Rakhtshah, Jamshid,Yousefi Seyf, Jaber,Ali Arabian, Iman
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- Copper(II)-Photocatalyzed N-H Alkylation with Alkanes
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We report a practical method for the alkylation of N-H bonds with alkanes using a photoinduced copper(II) peroxide catalytic system. Upon light irradiation, the peroxide serves as a hydrogen atom transfer reagent to activate stable C(sp3)-H bonds for the reaction with a broad range of nitrogen nucleophiles. The method enables the chemoselective alkylation of amides and is utilized for the late-stage functionalization of N-H bond containing pharmaceuticals with good to excellent yields. The mechanism of the reaction was preliminarily investigated by radical trapping experiments and spectroscopic methods.
- Donabauer, Karsten,K?nig, Burkhard,Narobe, Rok,Yakubov, Shahboz,Zheng, Yi-Wen
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p. 8582 - 8589
(2020/09/23)
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- Metal-free synthesis of activated ynesulfonamides and tertiary enesulfonamides
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An operationally simple synthesis of activated ynesulfonamides and enesulfonamides is described. Ynesulfonamides can be obtained through reaction of sulfonylamides with activated bromoalkynes and Triton B in a short time at room temperature. Likewise, terminal alkynes react with sulfonylamides to provide enesulfonamides. Z/E enesulfonamides can be transformed exclusively into E enesulfonamides.
- Andna, Lucile,Miesch, Laurence
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supporting information
p. 5688 - 5692
(2019/06/19)
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- Iron-Catalyzed Hydroamination and Hydroetherification of Unactivated Alkenes
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The hydrofunctionalization of alkenes, explored for over 100 years, offers the potential for a direct, atom-economical approach to value-added products. While thermodynamically favored, the kinetic barrier to such processes necessitates the use of catalysts to control selectivity and reactivity. Modern variants typically rely on noble metals that require different ligands for each class of hydrofunctionalization, thereby limiting generality. This Letter describes a general iron-based system that catalyzes the hydroamination and hydroetherification of simple unactivated olefins.
- Marcyk, Paul T.,Cook, Silas P.
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supporting information
p. 1547 - 1550
(2019/03/08)
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- Trispyrazolylborate Ligands Supported on Vinyl Addition Polynorbornenes and Their Copper Derivatives as Recyclable Catalysts
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Polynorbornenes prepared by vinyl addition polymerization and bearing pendant alkenyl groups serve as skeletons to support trispyrazolylborate ligands (Tpx) built at those alkenyl sites. Reaction with CuI in acetonitrile led to VA-PNB–TpxCu(NCMe) (VA-PBN=vinyl addition polynorbornene) with a 0.8–1.4 mmol incorporation of Cu per gram of polymer. The presence of tetracoordinated copper(I) ions was been assessed by FTIR studies on the corresponding VA-PNB-TpxCu(CO) adducts, in agreement with those on discrete TpxCu(CO). The new materials were employed as heterogeneous catalysts in several carbene- and nitrene-transfer reactions, showing a behavior similar to that of the homogeneous counterparts but also being recycled several times maintaining a high degree of activity and selectivity. This is the first example of supported Tpx ligands onto polymeric supports with catalytic applications.
- Molina de la Torre, Jesús A.,Pérez-Ortega, Ignacio,Beltrán, álvaro,Rodríguez, Manuel R.,Díaz-Requejo, M. Mar,Pérez, Pedro J.,Albéniz, Ana C.
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p. 556 - 563
(2018/12/11)
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- Sulfonamide Synthesis through Electrochemical Oxidative Coupling of Amines and Thiols
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Sulfonamides are key motifs in pharmaceuticals and agrochemicals, spurring the continuous development of novel and efficient synthetic methods to access these functional groups. Herein, we report an environmentally benign electrochemical method which enables the oxidative coupling between thiols and amines, two readily available and inexpensive commodity chemicals. The transformation is completely driven by electricity, does not require any sacrificial reagent or additional catalysts and can be carried out in only 5 min. Hydrogen is formed as a benign byproduct at the counter electrode. Owing to the mild reaction conditions, the reaction displays a broad substrate scope and functional group compatibility.
- Laudadio, Gabriele,Barmpoutsis, Efstathios,Schotten, Christiane,Struik, Lisa,Govaerts, Sebastian,Browne, Duncan L.,No?l, Timothy
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supporting information
(2019/04/16)
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- Sulfonamide Synthesis through Electrochemical Oxidative Coupling of Amines and Thiols
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Sulfonamides are key motifs in pharmaceuticals and agrochemicals, spurring the continuous development of novel and efficient synthetic methods to access these functional groups. Herein, we report an environmentally benign electrochemical method which enables the oxidative coupling between thiols and amines, two readily available and inexpensive commodity chemicals. The transformation is completely driven by electricity, does not require any sacrificial reagent or additional catalysts and can be carried out in only 5 min. Hydrogen is formed as a benign byproduct at the counter electrode. Owing to the mild reaction conditions, the reaction displays a broad substrate scope and functional group compatibility.
- Laudadio, Gabriele,Barmpoutsis, Efstathios,Schotten, Christiane,Struik, Lisa,Govaerts, Sebastian,Browne, Duncan L.,No?l, Timothy
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supporting information
p. 5664 - 5668
(2019/04/17)
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- Stereoinversion of Unactivated Alcohols by Tethered Sulfonamides
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The direct, catalytic substitution of unactivated alcohols remains an undeveloped area of organic synthesis. Moreover, catalytic activation of this difficult electrophile with predictable stereo-outcomes presents an even more formidable challenge. Described herein is a simple iron-based catalyst system which provides the mild, direct conversion of secondary and tertiary alcohols to sulfonamides. Starting from enantioenriched alcohols, the intramolecular variant proceeds with stereoinversion to produce enantioenriched 2- and 2,2-subsituted pyrrolidines and indolines, without prior derivatization of the alcohol or solvolytic conditions.
- Marcyk, Paul T.,Jefferies, Latisha R.,AbuSalim, Deyaa I.,Pink, Maren,Baik, Mu-Hyun,Cook, Silas P.
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supporting information
p. 1727 - 1731
(2019/01/21)
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- Three-Component Ring-Opening Reactions of Cyclic Ethers, α-Diazo Esters, and Weak Nucleophiles under Metal-Free Conditions
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A protocol for three-component reactions of cyclic ethers, α-diazo esters, and weak nitrogen, oxygen, carbon, and sulfur nucleophiles (pKa = 2.2-14.8) to afford a variety of structurally complex α-oxyalkylated esters is reported. These reactions involve intermolecular activation of the cyclic ether (present in excess) by the α-diazo ester to form an oxonium ylide under metal-free conditions, followed by ring opening by the nucleophile.
- Lu, Lin,Chen, Chuwei,Jiang, Huanfeng,Yin, Biaolin
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p. 14385 - 14395
(2018/11/27)
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- Designed To React: Terminal Copper Nitrenes and Their Application in Catalytic C?H Aminations
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Heteroscorpionate ligands of the bis(pyrazolyl)methane family have been applied in the stabilisation of terminal copper tosyl nitrenes. These species are highly active intermediates in the copper-catalysed direct C?H amination and nitrene transfer. Novel perfluoroalkyl-pyrazolyl- and pyridinyl-containing ligands were synthesized to coordinate to a reactive copper nitrene centre. Four distinct copper tosyl nitrenes were prepared at low temperatures by the reaction with SO2tBuPhINTs and copper(I) acetonitrile complexes. Their stoichiometric reactivity has been elucidated regarding the imination of phosphines and the aziridination of styrenes. The formation and thermal decay of the copper nitrenes were investigated by UV/Vis spectroscopy of the highly coloured species. Additionally, the compounds were studied by cryo-UHR-ESI mass spectrometry and DFT calculations. In addition, a mild catalytic procedure has been developed where the copper nitrene precursors enable the C?H amination of cyclohexane and toluene and the aziridination of styrenes.
- Moegling, Julian,Hoffmann, Alexander,Thomas, Fabian,Orth, Nicole,Liebh?user, Patricia,Herber, Ulrich,Rampmaier, Robert,Stanek, Julia,Fink, Gerhard,Ivanovi?-Burmazovi?, Ivana,Herres-Pawlis, Sonja
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supporting information
p. 9154 - 9159
(2018/07/25)
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- Decarboxylative sp 3 C-N coupling via dual copper and photoredox catalysis
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Over the past three decades, considerable progress has been made in the development of methods to construct sp 2 carbon-nitrogen (C-N) bonds using palladium, copper or nickel catalysis 1,2 . However, the incorporation of alkyl substrates to form sp 3 C-N bonds remains one of the major challenges in the field of cross-coupling chemistry. Here we demonstrate that the synergistic combination of copper catalysis and photoredox catalysis can provide a general platform from which to address this challenge. This cross-coupling system uses naturally abundant alkyl carboxylic acids and commercially available nitrogen nucleophiles as coupling partners. It is applicable to a wide variety of primary, secondary and tertiary alkyl carboxylic acids (through iodonium activation), as well as a vast array of nitrogen nucleophiles: nitrogen heterocycles, amides, sulfonamides and anilines can undergo C-N coupling to provide N-alkyl products in good to excellent efficiency, at room temperature and on short timescales (five minutes to one hour). We demonstrate that this C-N coupling protocol proceeds with high regioselectivity using substrates that contain several amine groups, and can also be applied to complex drug molecules, enabling the rapid construction of molecular complexity and the late-stage functionalization of bioactive pharmaceuticals.
- Liang, Yufan,Zhang, Xiaheng,MacMillan, David W. C.
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- PTAB mediated open air synthesis of sulfonamides, thiosulfonates and symmetrical disulfanes
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A facile methodology has been described which has successfully simplified the generation of sulfonamides, thiosulfonates and symmetric disulfanes. This “trio” of reactions occur in an open air metal free atmosphere and has also been scaled up to grams making it suitable for commercialization. The reactions also have been successfully carried out with asymmetric variants, thus contributing to the chiral pool. The user friendly “trio” enables easy generation of these versatile sulfur analogues and the reaction condition employed depict an economic outline.
- Sarkar, Debayan,Ghosh, Manoj Kumar,Rout, Nilendri
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supporting information
p. 2360 - 2364
(2018/05/24)
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- Redox Self-Adaptation of a Nitrene Transfer Catalyst to the Substrate Needs
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The development of iron catalysts for carbon–heteroatom bond formation, which has attracted strong interest in the context of green chemistry and nitrene transfer, has emerged as the most promising way to versatile amine synthetic processes. A diiron system was previously developed that proved efficient in catalytic sulfimidations and aziridinations thanks to an FeIIIFeIV active species. To deal with more demanding benzylic and aliphatic substrates, the catalyst was found to activate itself to a FeIIIFeIVL. active species able to catalyze aliphatic amination. Extensive DFT calculations show that this activation event drastically enhances the electron affinity of the active species to match the substrates requirements. Overall this process consists in a redox self-adaptation of the catalyst to the substrate needs.
- Gouré, Eric,Senthilnathan, Dhurairajan,Coin, Guillaume,Albrieux, Florian,Avenier, Frédéric,Dubourdeaux, Patrick,Lebrun, Colette,Maldivi, Pascale,Latour, Jean-Marc
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supporting information
p. 4305 - 4309
(2017/04/04)
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- Preparation N - alkyl toluene sulfonamide method
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The invention discloses a method for preparing N-alkyl-p-toluenesulfonamide. The method comprises the following steps: (1) dissolving anhydrous p-toluenesulfonic acid in a dichloromethane solvent, adding a catalyst and a molecular sieve 5A, and controlling the temperature to be 0-40 DEG C; (2) adding primary amine for a reaction, wherein the reaction temperature is 0-40 DEG C; (3) after the reaction is finished, carrying out suction filtration to remove the molecular sieve 5A; (4) washing a filtrate with an acid solution, then carrying out washing with an alkali solution and a salt solution in sequence, carrying out separation to obtain an organic phase, removing a drying agent after drying the organic phase with anhydrous sodium sulfate, and carrying out distillation to recover dichloromethane and obtain a crude product of N-alkyl-p-toluenesulfonamide; (5) carrying out washing with a 50% ethanol water solution, and carrying out weighing after drying. The method has the advantages that the catalyst is used, so that anhydrous p-toluenesulfonic acid can be directly reacted with primary amine in the dichloromethane organic solvent at low temperature; the molecular sieve 5A is added in the reaction between anhydrous p-toluenesulfonic acid and primary amine as a water absorbent, so that water generated in the reaction can be absorbed to ensure a smooth reaction process. According to liquid chromatography analysis, the purity and the yield of N-alkyl-p-toluenesulfonamide exceeds 98% and reaches about 40% respectively.
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Paragraph 0034; 0035
(2017/08/25)
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- Sustainable synthesis of sulfonamides using supported ionic liquid phase catalyst containing Keggin-type anion
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A silica-supported ionic liquid phase catalyst containing Keggin-type anion has been prepared by covalent grafting of ferrocene-tagged ionic liquid in a matrix of silica followed by anion metathesis reaction. This novel catalyst served as a robust heterogeneous catalyst for the synthesis of biologically active sulfonamides from 4-toluenesulfonyl chloride and amines. Additionally, recycling experiments showed that the catalyst could be reused five times.
- Jagadale, Megha,Khanapure, Sharanabasappa,Salunkhe, Rajashri,Rajmane, Mohan,Rashinkar, Gajanan
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p. 125 - 131
(2016/02/14)
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- Metal-free C-H sulfonamidation of pyrroles by visible light photoredox catalysis
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We report a one-step procedure for the preparation of N-(2-pyrrole)-sulfonamides from sulfonamides and pyrroles. The reaction uses visible light, an acridinium dye as photocatalyst and oxygen as the terminal oxidant for the oxidative C-N bond formation; structures of several reaction products were confirmed by X-ray structure analysis. The reaction is selective for pyrroles, due to the available oxidation power of the photocatalyst and the required stability of the carbocation intermediate under the reaction conditions.
- Meyer, Andreas Uwe,Berger, Anna Lucia,K?nig, Burkhard
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supporting information
p. 10918 - 10921
(2016/09/09)
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- Sulfonyl Azides as Precursors in Ligand-Free Palladium-Catalyzed Synthesis of Sulfonyl Carbamates and Sulfonyl Ureas and Synthesis of Sulfonamides
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(Chemical Equation Presented). An efficient synthesis of sulfonyl carbamates and sulfonyl ureas from sulfonyl azides employing a palladium-catalyzed carbonylation protocol has been developed. Using a two-chamber system, sulfonyl azides, PdCl2, and CO gas, released ex situ from Mo(CO)6, were assembled to generate sulfonyl isocyanates in situ, and alcohols and aryl amines were exploited as nucleophiles to afford a broad range of sulfonyl carbamates and sulfonyl ureas. A protocol for the direct formation of substituted sulfonamides from sulfonyl azides and amines via nucleophilic substitution was also developed.
- Chow, Shiao Y.,Stevens, Marc Y.,Odell, Luke R.
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p. 2681 - 2691
(2016/04/26)
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- NH4I-Catalyzed Synthesis of Sulfonamides from Arylsufonylhydrazides and Amines
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A novel and efficient approach to sulfonamides has been developed. Using TBHP as the oxidant and NH4I (20 mol%) as the catalyst, arylsulfonyl hydrazides reacted with amines to provide sulfonamides in moderate to good yields. Possible reaction pathway for the formation of the products was also discussed in this paper. Sulfonimides were synthesized through the oxidation coupling of arylsufonylhydrazides and amines by TBHP/NH4I system in moderate to good yields.
- Yu, Hui,Zhang, Yonghao
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supporting information
p. 359 - 362
(2016/04/26)
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- Electrochemical Oxidative Amination of Sodium Sulfinates: Synthesis of Sulfonamides Mediated by NH4I as a Redox Catalyst
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An efficient protocol for the synthesis of sulfonamides via the electrochemical oxidative amination of sodium sulfinates has been developed. The chemistry proceeds in a simple undivided cell employing a substoichiometric amount of NH4I that serves both as a redox catalyst and a supporting electrolyte; in this manner additional conducting salt is not required. A wide range of substrates, including aliphatic or aromatic secondary and primary amines, as well as aqueous ammonia, proved to be compatible with the protocol. Scale-up was possible, thereby demonstrating the practicality of the approach. The electrolytic process avoids the utilization of external oxidants or corrosive molecular iodine and therefore represents an environmentally benign means by which to achieve the transformation.
- Jiang, Yang-Ye,Wang, Qing-Qing,Liang, Sen,Hu, Li-Ming,Little, R. Daniel,Zeng, Cheng-Chu
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p. 4713 - 4719
(2016/07/06)
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- On the understanding of BF3·Et2O-promoted intra- and intermolecular amination and oxygenation of unfunctionalized olefins
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BF3·Et2O was found to be effective for both intra- and intermolecular amination and oxygenation of unfunctionalized olefins. In the presence of 3 equiv. of BF3·Et2O, intramolecular hydroamination of N-(pent-4-enyl)-p-toluenesulfonamides, N-(hex-5-enyl)-p-toluenesulfonamides, intermolecular hydroamination between sulfonamides and cyclohexene, norbornene or styrene, lactonization of pent-4-enoic acid or hex-5-enoic acid compounds and esterification of cyclohexene with different carboxylic acids all proceeded readily, leading to the corresponding amination or oxygenation products in up to 99% isolated yields. Preliminary NMR experiments and DFT calculations suggested that the intramolecular hydroamination reactions proceeded via a sulfonimidic acid intermediate (N=S-OH), and formation of the corresponding Bronsted acid HF or HBF4 was less likely.
- Yang, Chun-Hua,Fan, Wen-Wen,Liu, Gong-Qing,Duan, Lili,Li, Lin,Li, Yue-Ming
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p. 61081 - 61093
(2015/08/03)
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- Iodine-catalyzed expeditious synthesis of sulfonamides from sulfonyl hydrazides and amines
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A new synthesis of sulfonamides has been developed via an iodine-catalyzed sulfonylation of amines with arylsulfonyl hydrazides. This metal-free strategy employs readily accessible and easy to handle starting materials, catalysts and oxidants, and can be easily conducted under mild conditions, providing a convenient access to a wide range of sulfonamides in moderate to excellent yields within a short reaction time.
- Yotphan, Sirilata,Sumunnee, Ladawan,Beukeaw, Danupat,Buathongjan, Chonchanok,Reutrakul, Vichai
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p. 590 - 597
(2016/01/12)
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- Iodine-catalyzed oxidative amination of sodium sulfinates: A convenient approach to the synthesis of sulfonamides under mild conditions
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The iodine-catalyzed oxidative amination of sodium sulfinates in the presence of sodium percarbonate as the oxidant has been developed. The reaction shows good substrate scope and tolerates a wide range of functionalities in both amine and sodium sulfinate substrates. Aliphatic amines, heteroaromatic amines and hydrochloride salts of amines canbe employed as the amine sources in this transformation. Mechanistic studies indicated that a radical pathway might be involved in the reaction process. This transition-metalfree protocol offers an alternative and convenient approach for a preparation of a series of sulfonamides in moderate to good yields under mild conditions.
- Buathongjan, Chonchanok,Beukeaw, Danupat,Yotphan, Sirilata
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p. 1575 - 1582
(2015/03/04)
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- Copper-Catalyzed Ligand-Free Amidation of Benzylic Hydrocarbons and Inactive Aliphatic Alkanes
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An efficient copper-catalyzed amidation of benzylic hydrocarbons and inactive aliphatic alkanes with simple amides was developed. The protocol proceeded smoothly without any ligand, and a wide range of N-alkylated aromatic and aliphatic amides, sulfonamides, and imides were synthesized in good yields.
- Zeng, Hui-Ting,Huang, Jing-Mei
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supporting information
p. 4276 - 4279
(2015/09/15)
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- N-alkylation of sulfonamides with alcohols by Tf2O
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N-sulfonylpyrrolidines and N-alkyl sulfonamides were efficiently prepared via alkylation of sulfonamides with 1,4- diols or alcohols by Tf2O. The reaction occurred under mild reaction conditions in moderate to high yields and tolerated aryl and aliphatic sulfonamides.
- Yu, Ting Ting,Qi, Lan-Jun,Cui, Dong-Mei,Zhang, Chen,Zhao, Yan
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supporting information
p. 610 - 612
(2015/08/04)
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- Ruthenium(II) complexes containing a phosphine-functionalized thiosemicarbazone ligand: Synthesis, structures and catalytic C-N bond formation reactions via N-alkylation
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A series of ruthenium(II) complexes incorporating a thiosemicarbazone chelate tethered with a diphenylphosphine pendant have been studied. Thus, [(PNS-Et)RuCl(CO)(PPh3)] (1), [N,S-(PNS-Et)RuH(CO)(PPh3)2] (2) and [(PNS-Et)RuCl(PPh3)] (3) were synthesized by reactions of various RuII precursors with 2-(2-(diphenylphosphino)benzylidene)-N-ethylthiosemicarbazone (PNS-Et). However, complexation of PNS-Et with an equimolar amount of [RuCl2(dmso)4] resulted in two different entities [(PNS-Et)RuCl(dmso)2] (4) and [(PNS-Et)2Ru] (5) with different structural features in a single reaction. All the RuII complexes have been characterized by analytical and various spectroscopic techniques. Compounds 1-5 were recrystallized, and the X-ray crystal structures have been reported for 1, 2 and 5. In the complexes 1 and 3-5 the ligand coordinated in a tridentate monobasic fashion by forming PNS five- and six-membered rings, whereas in 2, the ligand coordinated in a bidentate monobasic fashion by forming a strained NS four-membered ring. Furthermore, compounds 1-5 showed catalytic activity in N-alkylation of heteroaromatic amines. Notably, complexes 1-3 were found to be very efficient catalysts toward N-alkylation of a wide range of heterocyclic amines with alcohols. In the presence of a catalytic amount of 2 with 50 mol% of KOH, N1,C5-dialkylation of 4-phenylthiazol-2-amine has been investigated. Reaction of in situ generated aldehyde with amine yields the N1,C5-dialkylated products through the hydride ion transformation from alcohol. Complexes 1-3 also catalyzed a variety of coupling reactions of benzyl alcohols and sulfonamides, which were realized often with 99% isolated yields. Advantageously, only one equivalent of the primary alcohol was consumed in the process.
- Ramachandran, Rangasamy,Prakash, Govindan,Selvamurugan, Sellappan,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz,Linert, Wolfgang,Gusev, Alexey
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p. 11405 - 11422
(2015/03/05)
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- A versatile tripodal Cu(I) reagent for C-N bond construction via nitrene-transfer chemistry: Catalytic perspectives and mechanistic insights on C-H aminations/amidinations and olefin aziridinations
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A CuI catalyst (1), supported by a framework of strongly basic guanidinato moieties, mediates nitrene-transfer from PhI=NR sources to a wide variety of aliphatic hydrocarbons (C-H amination or amidination in the presence of nitriles) and olefins (aziridination). Product profiles are consistent with a stepwise rather than concerted C-N bond formation. Mechanistic investigations with the aid of Hammett plots, kinetic isotope effects, labeled stereochemical probes, and radical traps and clocks allow us to conclude that carboradical intermediates play a major role and are generated by hydrogen-atom abstraction from substrate C-H bonds or initial nitrene-addition to one of the olefinic carbons. Subsequent processes include solvent-caged radical recombination to afford the major amination and aziridination products but also one-electron oxidation of diffusively free carboradicals to generate amidination products due to carbocation participation. Analyses of metal- and ligand-centered events by variable temperature electrospray mass spectrometry, cyclic voltammetry, and electron paramagnetic resonance spectroscopy, coupled with computational studies, indicate that an active, but still elusive, copper-nitrene (S = 1) intermediate initially abstracts a hydrogen atom from, or adds nitrene to, C-H and C=C bonds, respectively, followed by a spin flip and radical rebound to afford intra- and intermolecular C-N containing products.
- Bagchi, Vivek,Paraskevopoulou, Patrina,Das, Purak,Chi, Lingyu,Wang, Qiuwen,Choudhury, Amitava,Mathieson, Jennifer S.,Cronin, Leroy,Pardue, Daniel B.,Cundari, Thomas R.,Mitrikas, George,Sanakis, Yiannis,Stavropoulos, Pericles
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supporting information
p. 11362 - 11381
(2014/09/17)
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- Transition metal-free intermolecular a-C-H amination of ethers at room temperature
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We describe a new method for the intermolecular amination of the α-C-H bonds of ethers. A hypervalent iodine reagent was used as oxidant to enable the amination of cyclic and acyclic alkyl ethers with a wide range of amides, imides, and amines. The amination occurred at room temperature and without a transition metal catalyst. The method could be used to synthesize the anti-cancer prodrug Tegafur and its analogues.
- Buslov, Ivan,Hu, Xile
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supporting information
p. 3325 - 3330
(2015/02/02)
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- Mono- vs. dinuclear gold-catalyzed intermolecular hydroamidation
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Mono- and dinuclear gold catalysts were investigated in the intermolecular hydroamidation of olefins. Upon activation of [Ph3PAuCl] and [xantphos(AuCl)2] with various silver salts (AgOTf, Ag[BF 4], and Ag[SbF6]), diverging reactivity of the resulting cationic gold complexes was observed. It was found that both the binding ability of the counterion and the solvent have a significant impact on the reactivity of the mono- and dinuclear complexes. Copyright
- Serrano-Becerra, Juan M.,Maier, Alexander F. G.,Gonzalez-Gallardo, Sandra,Moos, Eric,Kaub, Christoph,Gaffga, Maximilian,Niedner-Schatteburg, Gereon,Roesky, Peter W.,Breher, Frank,Paradies, Jan
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p. 4515 - 4522
(2014/08/05)
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- Chemoselective deprotection of N-allylic amines using DDQ
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A highly chemoselective and simple method for the deprotection of N-allylic amines using DDQ has been developed. The use of DDQ in dichloromethane-water provides a mild and efficient one-step deallylation of a wide variety of orthogonally protected tertiary amine derivatives.
- Kumar, Pradeep,Cherian, Shijo K.,Jain, Ruchi,Show, Krishanu
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supporting information
p. 7172 - 7176
(2015/01/09)
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- Highly efficient one-pot synthesis of N-alkyl sulfonamides from alcohols using N-(p-toluenesulfonyl) imidazole (Tsim)
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A facile and efficient method for one-pot synthesis of N-alkyl sulfonamides from alcohols using N-(p-toluenesulfonyl)imidazole (TsIm) is described. In this protocol, treatment of various potassium sulfonylamide salts and alcohols in the presence of TsIm and triethylamine in refluxing DMF furnishes the corresponding N-alkyl sulfonamides in good to excellent yields. This methodology is highly efficient for reaction of various structurally diverse primary and secondary alcohols as well as potassium sulfonylamides. Also, the density functional theoretical calculations are employed to mechanistically study this protocol. [Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional text and figures.]
- Rad, Mohammad Navid Soltani,Behrouz, Somayeh,Nekoei, Abdo-Reza
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p. 465 - 476
(2014/04/03)
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- Copper-catalyzed intermolecular amidation and imidation of unactivated alkanes
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We report a set of rare copper-catalyzed reactions of alkanes with simple amides, sulfonamides, and imides (i.e., benzamides, tosylamides, carbamates, and phthalimide) to form the corresponding N-alkyl products. The reactions lead to functionalization at secondary C-H bonds over tertiary C-H bonds and even occur at primary C-H bonds. [(phen)Cu(phth)] (1-phth) and [(phen)Cu(phth)2] (1-phth2), which are potential intermediates in the reaction, have been isolated and fully characterized. The stoichiometric reactions of 1-phth and 1-phth2 with alkanes, alkyl radicals, and radical probes were investigated to elucidate the mechanism of the amidation. The catalytic and stoichiometric reactions require both copper and tBuOOtBu for the generation of N-alkyl product. Neither 1-phth nor 1-phth2 reacted with excess cyclohexane at 100 C without tBuOOtBu. However, the reactions of 1-phth and 1-phth2 with tBuOOtBu afforded N-cyclohexylphthalimide (Cy-phth), N-methylphthalimide, and tert-butoxycyclohexane (Cy-OtBu) in approximate ratios of 70:20:30, respectively. Reactions with radical traps support the intermediacy of a tert-butoxy radical, which forms an alkyl radical intermediate. The intermediacy of an alkyl radical was evidenced by the catalytic reaction of cyclohexane with benzamide in the presence of CBr4, which formed exclusively bromocyclohexane. Furthermore, stoichiometric reactions of [(phen)Cu(phth)2] with tBuOOtBu and (Ph(Me)2CO) 2 at 100 C without cyclohexane afforded N-methylphthalimide (Me-phth) from β-Me scission of the alkoxy radicals to form a methyl radical. Separate reactions of cyclohexane and d12-cyclohexane with benzamide showed that the turnover-limiting step in the catalytic reaction is the C-H cleavage of cyclohexane by a tert-butoxy radical. These mechanistic data imply that the tert-butoxy radical reacts with the C-H bonds of alkanes, and the subsequent alkyl radical combines with 1-phth2 to form the corresponding N-alkyl imide product.
- Tran, Ba L.,Li, Bijie,Driess, Matthias,Hartwig, John F.
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supporting information
p. 2555 - 2563
(2014/03/21)
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- Nonheme iron-mediated amination of C(sp3)-H bonds. Quinquepyridine-supported iron-imide/nitrene intermediates by experimental studies and DFT calculations
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The 7-coordinate complex [Fe(qpy)(MeCN)2](ClO4) 2 (1, qpy = 2,2′:6′,2″:6″, 2′′′:6′′′,2′′′′- quinquepyridine) is a highly active nonheme iron catalyst for intra- and intermolecular amination of C(sp3)-H bonds. This complex effectively catalyzes the amination of limiting amounts of not only benzylic and allylic C(sp3)-H bonds of hydrocarbons but also the C(sp3)-H bonds of cyclic alkanes and cycloalkane/linear alkane moieties in sulfamate esters, such as those derived from menthane and steroids cholane and androstane, using PhI=NR or "PhI(OAc)2 + H2NR" [R = Ts (p-toluenesulfonyl), Ns (p-nitrobenzenesulfonyl)] as nitrogen source, with the amination products isolated in up to 93% yield. Iron imide/nitrene intermediates [Fe(qpy)(NR)(X)]n+ (CX, X = NR, solvent, or anion) are proposed in these amination reactions on the basis of experimental studies including ESI-MS analysis, crossover experiments, Hammett plots, and correlation with C-H bond dissociation energies and with support by DFT calculations. Species consistent with the formulations of [Fe(qpy)(NTs)2] 2+ (CNTs) and [Fe(qpy)(NTs)]2+ (C) were detected by high-resolution ESI-MS analysis of the reaction mixture of 1 with PhI=NTs (4 equiv). DFT calculations revealed that the reaction barriers for H-atom abstraction of cyclohexane by the ground state of 7-coordinate C NTs and ground state of C are 15.3 and 14.2 kcal/mol, respectively, in line with the observed high activity of 1 in catalyzing the C-H amination of alkanes under mild conditions.
- Liu, Yungen,Guan, Xiangguo,Wong, Ella Lai-Ming,Liu, Peng,Huang, Jie-Sheng,Che, Chi-Ming
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supporting information
p. 7194 - 7204
(2013/06/27)
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- From ynamides to highly substituted benzo[b]furans: Gold(I)-catalyzed 5-endo-dig-cyclization/rearrangement of alkylic oxonium intermediates
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A series of arylynamides with alkyloxy groups at the ortho position of the aryl group was prepared through a short alkylation/cross-coupling/amidation sequence. The gold-catalyzed conversion of these substrates combined both C-O and C-C formation steps, thus providing benzofurans with amine functionalities at the 2-position and alkyl groups at the 3-position. Cross-over experiments showed that the alkyl-migration step was an intermolecular process. X-ray crystal-structure analysis of two of the products supported our structural assignment. In some cases, the corresponding benzofurans without the alkyl group at the 3-position were obtained as side-products, which were formed through a competing protodeauration process. Golden touch: Arylynamides with o-alkyloxy groups were prepared through an alkylation/cross-coupling/amidation sequence. Their Au-catalyzed conversion provided benzofurans with amine groups at the 2-position and alkyl groups at the 3-position. Copyright
- Blanco Jaimes, Maria Camila,Weingand, Vanessa,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 12504 - 12511
(2013/09/23)
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- Sulfonamide synthesis via oxyma-O-sulfonates - Compatibility to acid sensitive groups and solid-phase peptide synthesis
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A milder and more efficient procedure for the synthesis of sulfonamides by activating sulfonic acid groups as the corresponding sulfonate esters of ethyl 2-cyano-2-(hydroxyimino)acetate (Oxyma) is reported. This method is greener than all other existing protocols for the purpose. Other important advantages lie in (a) its applicability to less nucleophilic anilines under ambient and milder conditions and (b) its compatibility with solid phase peptide synthesis and acid-labile groups such as trityl (Trt) and tBu, which empowers the solid phase synthesis of sulfonamides of various peptides. To illustrate this, the syntheses of three sulfonamide derivatives of the peptide GAILG-NH2, which is relevant in the context of drug design against type 2 diabetes, are demonstrated by using Fmoc-based solid-phase peptide synthesis (SPPS). The activation of sulfonic acids as their corresponding O-sulfonate esters facilitates sulfonamide synthesis, which can be applied to those substrates that possess acid-labile functional groups and is compatible with solid phase synthesis. Copyright
- Palakurthy, Nani Babu,Dev, Dharm,Rana, Shubhasmin,Nadimpally, Krishna Chaitanya,Mandal, Bhubaneswar
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p. 2627 - 2633
(2013/06/04)
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- Stereoselective direct reductive amination of ketones with electron-deficient amines using Re2O7/NaPF6 catalyst
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The first example of direct reductive amination (DRA) of ketones with electron-deficient amines (EDA) such as Cbz-, Boc-, EtOCO-, Fmoc-, Bz-, ArSO2-, etc. protected amines have been achieved using catalytic Re2O7/NaPF6. Excellent chemoselectivities as well as diastereoselectivity (for 2-alkyl cyclohexanones) were obtained. The Royal Society of Chemistry 2013.
- Das, Braja Gopal,Ghorai, Prasanta
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supporting information
p. 4379 - 4382
(2013/08/23)
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- Half-sandwich scorpionates as nitrene transfer catalysts
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Scorpionate complexes of the middle to late 3d transition metals [(L)M(NCMe)3](BF4)n (M = Mn, Fe, Co, Ni: 1 M, L = tris(3,5-dimethylpyrazol-1-yl)methane, TpmMe,Me, n = 2; 2M, L = tris(3-phenylpyrazol-1-yl)methane, TpmPh, n = 2; 3M except 3Mn, L = hydrotris(3,5-dimethylpyrazol-1-yl) borate, [TpMe,Me]-, n = 1; 4M, L = hydrotris(3-phenyl-5-methylpyrazol-1-yl)borate, [TpPh,Me] -, n = 1) were examined as catalysts for styrene aziridination and THF amination using phenyl-N-tosyliodinane as a nitrene donor. [(Tpm Me,Me)Fe(NCMe)3](BF4)2 (1 Fe) was identified as the most active catalyst, giving nearly quantitative nitrene transfer yields at 5 mol % loadings. The reactivity of 1Fe with a wider range of organic substrates was also explored, and a striking observation was strong selectivity for aromatic rather than benzylic amination for alkylaromatic substrates.
- Liang, Shengwen,Jensen, Michael P.
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p. 8055 - 8058
(2013/02/22)
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- Zirconium-catalyzed intermolecular hydroamination of alkynes with primary amines
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A simple catalyst system generated in situ by combination of 5 mol-% [Zr(NMe2)4] and 10 mol-% of a sulfonamide catalyzes the intermolecular hydroamination of alkynes with primary amines. At elevated temperatures, hydroamination is achieved with both internal and terminal alkynes as well as with sterically demanding and less demanding primary amines. In contrast, secondary amines do not react under identical conditions. Of the sulfonamide additives investigated, sterically demanding tosylamides such as N-(tert-butyl)-p-toluenesulfonamide give the best results. The regioselectivity of the addition of amine to unsymmetrically substituted internal as well as terminal alkynes is significantly influenced by the nature of the sulfonamide additive. In particular, the successful use of sterically less demanding primary amines such as n-hexyl-or benzylamine clearly indicates that the assumption that Zr catalysts generally form catalytically inactive bridging μ2-imido dimers or other unreactive intermediates in the presence of these amines is not correct. Intermolecular hydroamination reactions of alkynes with primary amines that are sterically less demanding than 2,6-dimethylaniline can be achieved with in situ generated zirconium catalysts. This finding is highly important for a better and more general understanding of the mechanism of group 4 metal-catalyzed hydroamination reactions. Copyright
- Born, Karolin,Doye, Sven
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supporting information; experimental part
p. 764 - 771
(2012/03/22)
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- Cs2CO3 catalyzed rapid and efficient conversion of amines into sulfonamides; Alcohols and phenols into sulfonic esters
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A simple and efficient method has been developed for the sulfonylation of several amines, alcohols, and phenols by p-toluenesulphonylchloride (p-TsCl) in the presence of catalytic amount of Cs2CO3 at 25C to obtain sulfonamides and sulfonic esters in very good yields. Cs2CO3 has been found to be highly efficient catalyst. Taylor & Francis Group, LLC.
- Reddy, M. B. Madhusudana,Pasha
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experimental part
p. 1867 - 1875
(2011/10/11)
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- DABCO-bis (sulfur dioxide), DABSO, as a convenient source of sulfur dioxide for organic synthesis: Utility in sulfonamide and sulfamide preparation
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The charge-transfer complex generated from the combination of DABCO and sulfur dioxide, DABSO, is a bench-stable colorless solid suitable for use in organic synthesis as a replacement for gaseous sulfur dioxide. The complex can be combined with Grignard reagents to form sulfinates, which can then be converted in situ to a series of sulfonamides. Alternatively, reaction with anilines and iodine leads to the formation of a series of sulfamides. Cheletropic addition between DABSO and 2,3-dimethylbutadiene provides the corresponding sulfolene.
- Woolven, Holly,Gonzalez-Rodriguez, Carlos,Marco, Isabel,Thompson, Amber L.,Willis, Michael C.
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supporting information; experimental part
p. 4876 - 4878
(2011/12/05)
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- The hydroamination of alkenes with sulfonamides catalyzed by the recyclable silica gel supported triflic acid
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The vast applications of triflic acid (TfOH) in catalysis are severely limited by its corrosive and fuming properties. Immobilization of TfOH on silica gel well solves these problems and affords efficient recovery and reusability of TfOH. Two types of supported TfOH, the prepared silica gel supported TfOH and the in situ silica gel adsorbed TfOH, both exhibit good catalytic activity and reusability in the hydroamination of alkene with sulfonamide. The in situ silica gel adsorbed catalyst has been used for 5 runs with maintained reactivities and yields, which are superior to the performance of the prepared silica gel supported TfOH. For a series of alkenes and various sulfonamides, the heterogeneous hydroamination reactions catalyzed by both types of silica gel supported TfOH to afford similar moderate to excellent yields.
- Liu, Pei Nian,Xia, Fei,Zhao, Zheng Le,Wang, Qing Wei,Ren, Yu Jie
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supporting information; experimental part
p. 6113 - 6117
(2011/12/01)
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- Gold versus silver-catalyzed intermolecular hydroaminations of alkenes and dienes
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Comparative studies about the hydroamination of unactivated alkenes and dienes catalyzed by either cationic gold(I) triphenyl phosphite complexes or silver salts were performed using sulfonamides, anilines and carbamates as nucleophiles. Gold-catalyzed reactions generally, need lower loadings than those carried out with silver salts. Simple alkenes react only with sulfonamides and weak aromatic amines such as p-nitroaniline, whereas for conjugated dienes carbamates can also be used. Carbon-carbon double bond isomerization is observed only with gold similarly to when triflic acid was used, affording mixtures of regioisomeric products in the same cases. Silver-catalyzed hydroaminations failed with terminal alkenes, except with styrenes. Conjugate dienes can be hydroaminated either at 85 °C in toluene or at room temperature in dichloromethane. Non-conjugated 1,4- and 1,5-dienes suffer double hydroamination leading to saturated N-tosylated heterocyclic amines The catalytic cycle for the silver(I)-catalyzed hydroamination process has been computationally analyzed, resembling gold(I)-catalyzed processes, although with some significant differences. Copyright
- Giner, Xavier,Najera, Carmen,Kovacs, Gabor,Lledos, Agusti,Ujaque, Gregori
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experimental part
p. 3451 - 3466
(2012/02/04)
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- Sulfonamide synthesis using N-hydroxybenzotriazole sulfonate: An alternative to pentafluorophenyl (PFP) and trichlorophenyl (TCP) esters of sulfonic acids
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The N-hydroxybenzotriazole (HOBt) sulfonate esters undergo amidation under ambient conditions in the presence of di-isopropylethyl amine. This method can be applied to varieties of amines including sterically hindered amino acid esters in less time with reasonably good yields. HOBt ester of sulfonic acids can be a replacement for pentafluorophenyl and trichlorophenyl ester as well as chloride moiety of sulfonyl chloride for amidation.
- Palakurthy, Nani Babu,Mandal, Bhubaneswar
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p. 7132 - 7134
(2012/02/01)
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- Triflic acid catalyzed reductive coupling reactions of carbonyl compounds with O-, S-, and N-nucleophiles
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Highly efficient metal-free reductive coupling reactions of aldehydes and ketones with a range of nucleophiles in the presence of triflic acid (1-5 mol %) as the catalyst are presented. The reactions can be performed at ambient temperature without exclusion of moisture or air. A range of symmetrical and unsymmetrical ethers were obtained by this method in high yields and short reaction times. For the first time, the influence of additional functionalization has been studied. Furthermore, the formation of thioethers from ketones (by addition of unmodified thiols) and of sulfonamides from either aldehydes or ketones has been achieved under catalytic conditions.
- Gellert, Beate A.,Kahlcke, Nils,Feurer, Markus,Roth, Stefanie
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supporting information; experimental part
p. 12203 - 12209
(2011/11/07)
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