- Cu-based nanoalloys in the base-free ullmann heterocyle-aryl ether synthesis
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We report the first liquid-liquid Ullmann etherification process mediated not only by oxidatively stable Cu but also by CuZn and CuSn nanoparticle catalysts in conjunction with microwave heating that also avoids the use of solid and expensive bases. Condi
- Engels, Volker,Benaskar, Faysal,Patil, Narendra,Rebrov, Evgeny V.,Hessel, Volker,Hulshof, Lumbertus A.,Jefferson, David A.,Vekemans, Jef A. J. M.,Karwal, Saurabh,Schouten, Jaap C.,Wheatley, Andrew E. H.
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Read Online
- Copper(0) in the Ullmann heterocycle-aryl ether synthesis of 4-phenoxypyridine using multimode microwave heating
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The action of nanoparticulate copper catalysts with a mean particle size of 10 nm in the Ullmann ether synthesis is reported using multimode microwave heating and employing stable chloropyridine salts and unactivated phenol, with stabilized copper nanopar
- Benaskar, Faysal,Engels, Volker,Patil, Narendra,Rebrov, Evgeny V.,Meuldijk, Jan,Hessel, Volker,Hulshof, Lumbertus A.,Jefferson, David A.,Schouten, Jaap. C.,Wheatley, Andrew E.H.
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Read Online
- Nickel-Catalyzed Etherification of Phenols and Aryl Halides through Visible-Light-Induced Energy Transfer
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Notwithstanding some progress in nickel-catalyzed etherification of alkanols and arylhalides, the ability of such a Ni-catalyzed transformation employing phenols to diaryl ethers is unsuccessful due to phenolates with much lower reduction potentials, which suppress the oxidation of nickel(II) intermediates into requisite Ni(III) species. We herein report visible-light-initiated, nickel-catalyzed O-arylation of phenols with arylhalides using t-BuNH(i-Pr) as the base and thioxanthen-9-one as the photosensitizer under visible light. This photocoupling exhibits a broad substrate scope.
- Zhu, Da-Liang,Jiang, Shan,Wu, Qi,Wang, Hao,Li, Hai-Yan,Li, Hong-Xi
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supporting information
p. 8327 - 8332
(2021/10/25)
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- N - And O -arylation of pyridin-2-ones with diaryliodonium salts: Base-dependent orthogonal selectivity under metal-free conditions
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Metal-free N- and O-arylation reactions of pyridin-2-ones as ambident nucleophiles have been achieved with diaryliodonium salts on the basis of base-dependent chemoselectivity. In the presence of N,N-diethylaniline in fluorobenzene, pyridin-2-ones were very selectively converted to N-arylated products in high yields. On the other hand, the O-arylation reactions smoothly proceeded with the use of quinoline in chlorobenzene, leading to high yields and selectivities. In these methods, a variety of pyridin-2-ones in addition to pyridin-4-one and a set of diaryliodonium salts were accepted as suitable reaction partners.
- Abe, Yusuke,Hanazawa, Natsumi,Katagiri, Kotone,Kuriyama, Masami,Ono, Shimpei,Onomura, Osamu,Yamamoto, Kosuke
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p. 8295 - 8300
(2020/09/09)
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- Selective Functionalization of Aminoheterocycles by a Pyrylium Salt
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The functionalization of aminoheterocycles by using a pyrylium tetrafluoroborate reagent (Pyry-BF4) is presented. This reagent efficiently condenses with a great variety of heterocyclic amines and primes the C?N bond for nucleophilic aromatic substitution. More than 60 examples for the formation of C?O, C?N, C?S, or C?SO2R bonds are disclosed herein. In contrast to C?N activation through diazotization and polyalkylation, this method is characterized by its mild conditions and impressive functional-group tolerance. In addition to small-molecule derivatization, Pyry-BF4 allows the introduction of functional groups in a late-stage fashion to furnish highly functionalized structures.
- Moser, Daniel,Duan, Yaya,Wang, Feng,Ma, Yuanhong,O'Neill, Matthew J.,Cornella, Josep
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p. 11035 - 11039
(2018/07/31)
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- Spectroscopic Studies of the Chan-Lam Amination: A Mechanism-Inspired Solution to Boronic Ester Reactivity
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We report an investigation of the Chan-Lam amination reaction. A combination of spectroscopy, computational modeling, and crystallography has identified the structures of key intermediates and allowed a complete mechanistic description to be presented, including off-cycle inhibitory processes, the source of amine and organoboron reactivity issues, and the origin of competing oxidation/protodeboronation side reactions. Identification of key mechanistic events has allowed the development of a simple solution to these issues: manipulating Cu(I) → Cu(II) oxidation and exploiting three synergistic roles of boric acid has allowed the development of a general catalytic Chan-Lam amination, overcoming long-standing and unsolved amine and organoboron limitations of this valuable transformation.
- Vantourout, Julien C.,Miras, Haralampos N.,Isidro-Llobet, Albert,Sproules, Stephen,Watson, Allan J. B.
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supporting information
p. 4769 - 4779
(2017/04/11)
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- Synthesis of copper nanoparticles supported on a microporous covalent triazine polymer: An efficient and reusable catalyst for O-arylation reaction
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Copper nanoparticles were supported on a microporous covalent triazine polymer prepared by the Friedel-Crafts reaction (Cu@MCTP-1). The resulting material was characterized by powder X-ray diffraction, thermogravimetric analysis, N2 adsorption-desorption isotherms at 77 K, transmission electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectroscopy, and Cu particles with an average size of 3.0 nm and a BET total surface area of ca. 1002 m2 g-1 were obtained. Cu@MCTP-1 was evaluated as a heterogeneous catalyst for the Ullmann coupling of O-arylation over a series of aryl halides and phenols without employing expensive ligands or inert atmosphere, which produced an excellent yield of the corresponding diaryl ethers. The catalyst could be recovered by simple centrifugation and was reusable at least five times with only a slight decrease in catalytic activity.
- Puthiaraj, Pillaiyar,Ahn, Wha-Seung
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p. 1701 - 1709
(2016/04/05)
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- A counteranion triggered arylation strategy using diaryliodonium fluorides
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A mild and transition metal-free counteranion triggered arylation strategy has been developed using diaryliodonium fluorides. The fluoride counteranion within the hypervalent iodonium species displays unusual reactivity that activates a phenolic O-H bond leading to electrophilic O-arylation. A wide range of phenols and diaryliodonium salts are compatible with this transformation under remarkably mild conditions. Furthermore, we pre-empt the wider implications of this strategy by demonstrating the compatibility of the arylation tactic with latent carbon nucleophiles.
- Chan,McNally,Toh,Mendoza,Gaunt
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p. 1277 - 1281
(2015/02/05)
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- Graphene oxide grafted with Pd17Se15 nano-particles generated from a single source precursor as a recyclable and efficient catalyst for C-O coupling in O-arylation at room temperature
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The Pd17Se15 nanoparticles, synthesized for the first time from a single source precursor [Pd(L)Cl2] {L = 1,3-bis(phenylselenyl)propan-2-ol} and grafted onto graphene oxide, show high catalytic activity in C-O coupling between aryl/heteroaryl chlorides/bromides and phenol at room temperature (Pd loading 1 mol%; yield up to 94%).
- Joshi, Hemant,Sharma, Kamal Nayan,Sharma, Alpesh K.,Prakash, Om,Singh, Ajai Kumar
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supporting information
p. 7483 - 7485
(2013/08/23)
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- Low catalyst loadings for copper-catalyzed O-arylation of phenols with aryl and heteroaryl halides under mild conditions
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A practical and mild strategy has been developed for the cross-coupling of O-arylation of phenol with differently substituted aryl halides and heteroaryl iodides using low catalyst loading of copper iodide under low operating temperature in DMF with TMHD as the ligand and Cs2CO3 as the base. This method tolerates a variety of functional groups including sterically hindered phenols and heteroaryl iodides to afford products in good to excellent yields (up to 95%). Georg Thieme Verlag Stuttgart. New York.
- Yong, Fui-Fong,Teo, Yong-Chua,Yan, Yaw-Kai,Chua, Guan-Leong
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supporting information; experimental part
p. 101 - 106
(2012/02/03)
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- New Cu-based catalysts supported on TiO2 films for Ullmann SNAr-type C-O coupling reactions
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New routes for the preparation of highly active TiO2-supported Cu and CuZn catalysts have been developed for C-O coupling reactions. Slurries of a titania precursor were dip-coated onto glass beads to obtain either structured mesoporous or non-porous titania thin films. The Cu and CuZn nanoparticles, synthesized using a reduction by solvent method, were deposited onto calcined films to obtain a Cu loading of 2 wt %. The catalysts were characterized by inductively coupled plasma (ICP) spectroscopy, temperature-programmed oxidation/reduction (TPO/TPR) techniques, 63Cu nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD), scanning and transmission electron microscopy (S/TEM-EDX) and X-ray photo-electron spectroscopy (XPS). The activity and stability of the catalysts obtained have been studied in the C-O Ullmann coupling of 4-chloropyridine and potassium phenolate. The titania-supported nanoparticles retained catalyst activity for up to 12 h. However, catalyst deactivation was observed for longer operation times due to oxidation of the Cu nanoparticles. The oxidation rate could be significantly reduced over the CuZn/TiO2 catalytic films due to the presence of Zn. The 4-phenoxypyridine yield was 64 % on the Cu/nonporous TiO2 at 120 °C. The highest product yield of 84 % was obtained on the Cu/mesoporous TiO2 at 140 °C, corresponding to an initial reaction rate of 104 mmol gcat-1 s-1. The activation energy on the Cu/mesoporous TiO2 catalyst was found to be (144±5) kJ mol-1, which is close to the value obtained for the reaction over unsupported CuZn nanoparticles (123±3 kJ mol-1) and almost twice the value observed over the catalysts deposited onto the non-porous TiO2 support (75±2 kJ mol-1). Copyright
- Benaskar, Faysal,Engels, Volker,Rebrov, Evgeny V.,Patil, Narendra G.,Meuldijk, Jan,Thuene, Peter C.,Magusin, Pieter C. M. M.,Mezari, Brahim,Hessel, Volker,Hulshof, Lumbertus A.,Hensen, Emiel J. M.,Wheatley, Andrew E. H.,Schouten, Jaap C.
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supporting information; experimental part
p. 1800 - 1810
(2012/04/10)
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- HETEROARYL ARYL ETHERS
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The present invention relates to a process for the preparation of optionally substituted heteroaryl aryl ethers, in particular of phenoxypyridines.
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Page/Page column 4
(2010/07/10)
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- Effect of microwave heating on Ullmann-type heterocycle-aryl ether synthesis using chloro-heterocycles
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Ullmann ether synthesis was conducted on a variety of chloro-heterocycles with different phenols using optimized conditions involving copper powder and cesium carbonate. On many substrates, microwave heating afforded higher yields in significantly shorter reaction times compared to conventional heating conditions. These findings provide a facile method for aryl ether synthesis from chloropyridines, chloroquinolines, and chlorobenzothiazoles.
- D'Angelo, Noel D.,Peterson, Joseph J.,Booker, Shon K.,Fellows, Ingrid,Dominguez, Celia,Hungate, Randall,Reider, Paul J.,Kim, Tae-Seong
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p. 5045 - 5048
(2007/10/03)
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- Aromatic sulfone hydroxamic acid metalloprotease inhibitor
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A treatment process is disclosed that comprises administering an effective amount of an aromatic sulfone hydroxamic acid that exhibits excellent inhibitory activity of one or more matrix metalloprotease (MMP) enzymes, such as MMP-2, MMP-9 and MMP-13, while exhibiting substantially less inhibition at least of MMP-1 to a host having a condition associated with pathological matrix metalloprotease activity. Also disclosed are metalloprotease inhibitor compounds having those selective activities, processes for manufacture of such compounds and pharmaceutical compositions using an inhibitor. A contemplated compound corresponds in structure to formula B, below,
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- Synthesis of substituted pyridines by the reactions of halopyridines with sulfur, oxygen and carbon nucleophiles under focused microwave irradiation
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The nucleophilic substitution reactions of halopyridines with sulfur, oxygen and carbon nucleophiles under microwave irradiation was complete within several minutes with yields up to 99%. The method using microwave irradiation is superior to those conducted under conventional heating processes.
- Cherng, Yie-Jia
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p. 4931 - 4935
(2007/10/03)
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- Metalloproteinase inhibitors-compositions, uses preparation and intermediates thereof
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The invention relates to compounds of the formula 1: wherein: Z is O or S; V is a divalent radical which together with C* and N forms a ring having six ring atoms, where each of said ring atoms other than C* and N independently is unsubstituted or substituted by a suitable substituent, and at least one of said other ring atoms is a heteroatom selected from O, N and S, and the remainder are carbon atoms; and Ar is an aryl or heteroaryl group; and pharmaceutically acceptable prodrugs, salts and solvates thereof. The invention further relates to pharmaceutically acceptable prodrugs, salts and solvates of these compounds. The invention also relates to methods of inhibiting the activity of metalloproteinases by administering a compound of the formula I or a prodrug, salt of solvate thereof. The invention further relates to pharmaceutical compositions comprising an effective amount of these compounds, prodrugs, salts, and solvates. The invention still further relates to methods and intermediates useful for preparing these compounds, prodrugs, salts, and solvates.
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- Metalloproteinase inhibitors and intermediates useful for their preparation
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PCT No. PCT/US96/19328 Sec. 371 Date Jun. 29, 1998 Sec. 102(e) Date Jun. 29, 1998 PCT Filed Dec. 5, 1996 PCT Pub. No. WO97/20824 PCT Pub. Date Jun. 12, 1997The invention relates to compounds of formula (1) wherein: Z is O or S; V is a divalent radical which together with C* and N forms a ring having six ring atoms, where each of said ring atoms other than C* and N independently is unsubstituted or substituted by a suitable substituent, and at least one of said other ring atoms is a heteroatom selected from O, N and S, and the remainder is carbon atoms; and Ar is an aryl or heteroaryl group; and pharmaceutically acceptable prodrugs, salts and solvates thereof. The invention further relates to pharmaceutically acceptable prodrugs, salts and solvates of these compounds. The invention also relates to methods of inhibiting the activity of metalloproteinases by administering a compound of formula (1) or a prodrug, salt or solvate thereof. The invention further relates to pharmaceutical compositions comprising an effective amount of these compounds, prodrugs, salts, and solvates. The invention still further relates to methods and intermediates useful for preparing these compounds, prodrugs, salts, and solvates.
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- Chemical model studies on the monoamine oxidase-B catalyzed oxidation of 4-substituted 1-cyclopropyl-1,2,3,6-tetrahydropyridines
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Two catalytic pathways have been proposed for the flavoenzyme monoamine oxidase B (MAO-B-one based on an initial single electron transfer (SET) step from the nitrogen lone pair and the second based on an initial α-carbon hydrogen atom transfer (HAT) step. The SET pathway is consistent with the mechanism based inactivation properties of various cyclopropylamines. The observation that MAO-B catalyzes the efficient oxidation of certain 1- cyclopropyl-4-substituted-1,2,3,6-tetrahydropyridines to the corresponding dihydropyridinium metabolites suggests that the catalytic pathway for these cyclic tertiary allylamines may not proceed via the putative SET generated aminyl radical cations. The present paper describes the chemical fate of a series of N-cyclopropyltetrahydropyridines examined under reaction conditions that model the SET and the HAT pathways. All of the test compounds were rapidly converted under HAT reaction conditions to their dihydropyridinium products. Although the test compounds also were oxidized rapidly under SET conditions, no evidence for dihydropyridinium product formation was observed. The products that were identified most likely were formed after cyclopropyl ring opening of the initially formed cyclopropylaminyl radical cation. The results are discussed in terms of the mechanism of MAO-B catalysis.
- Franot, Christelle,Mabic, Stephane,Castagnol Jr., Neal
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p. 283 - 291
(2007/10/03)
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- SYNTHESIS OF PHENOXYPYRIDINES UNDER PHASE TRANSFER CATALYSIS CONDITIONS
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Reactions of halopyridines with alkali metal phenoxides in a two phase liquid-solid catalytic system, rather than in a liquid-liquid phase transfer catalytic system, make it possible to prepare 2-, 3-, and 4-phenoxypyridines from unactivated bromo- or chloropyridines and 2-chloropicolines.In polyhalogenated pyridines only α- and γ-halogen atoms undergo substitution. 7,8-Dibromo-6-azaphenoxane has been prepared by the reaction of 2,3,5,6-tetrabromopyridine with the dipotassium salt of pyrocatechol.
- Abele, E. M.,Gol'dberg, Yu. Sh.,Gavars, M. P.,Gaukhman, A. P.,Shimanskaya, M. V.
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p. 290 - 294
(2007/10/02)
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