- Organozinc-mediated direct cross-coupling under microwave irradiation
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We report a direct cross-coupling reaction between (het)aryl pivalates/tosylates and di(het)arylzinc species in 2-methyltetrahydrofuran/N-methyl pyrrolidone (1:1), which occurs via C–O bond cleavage under microwave irradiation. The reaction takes place smoothly in short reaction times without the addition of any catalyst or ligand. The reaction is suitable for a broad scope of substrates and exhibits good functional group compatibility, utilizes a simple work-up procedure, and gives the desired products in high purity.
- Li, Chun-Jing
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p. 869 - 875
(2021/07/02)
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- A general palladium-catalyzed cross-coupling of aryl fluorides and organotitanium (IV) reagents
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Pd(OAc)2/1-[2-(di-tert-butylphosphanyl)phenyl]-4-methoxy-piperidine was demonstrated to effectively catalyze cross-coupling of aryl fluoride and aryl(alkyl) titanium reagent. Both electron-deficient and electron-rich aryl fluoride can react effectively with nucleophile and provide extensive functional groups tolerance. 2-Arylated product was realized by selective activation of the C–F bond. Graphic abstract: [Figure not available: see fulltext.].
- He, Xiao-Yun
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p. 823 - 832
(2021/07/19)
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- C–H Arylation of N-Heteroarenes under Metal-Free Conditions and its Application towards the Synthesis of Pentabromo- and Pentachloropseudilins
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Herein, we are reporting metal-free conditions for radical initiation and direct C–H arylation of N-heteroarenes. Starting from aniline, the corresponding arenediazonium salt generated in situ is reduced to an aryl radical in the presence of chloropromazine hydrochloride, a new reagent for this application. The optimized procedures are mild, operationally simple, and are working successfully with more diverse substrates in comparison to reported methods. The optimized method is also employed for the synthesis of marine natural products Pentabromo- and Pentachloropseudilins (PBP/PCP). In the present study, we also validated the potential of the Pentachloropseudilin (PCP), thus synthesized, for inhibition of Myosin1 function in mammalian cells and confirmed that PCP phenocopies Myosin1c depletion in cells.
- Kumar, Mukesh,Sharma, Shweta,Sil, Parijat,Kushwaha, Manoj,Mayor, Satyajit,Vishwakarma, Ram A.,Singh, Parvinder Pal
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supporting information
p. 3591 - 3598
(2019/06/20)
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- Perylenequinonoid-catalyzed photoredox activation for the direct arylation of (het)arenes with sunlight
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Naturally occurring perylenequinonoid pigments (PQPs) have attracted considerable attention owing to their excellent properties of photosensitization. They have been widely investigated as an aspect of photophysics and photobiology. However, their applications in photocatalysis are yet to be explored. We report here that sunlight along with 1 mol% cercosporin, which is one of the perylenequinonoid pigments, catalyzes the direct C-H bond arylation of (het)arenes by a photoredox process with good regioselectivity and broad functional group compatibility. Furthermore, a gram-scale reaction with great conversions of substrates was achieved even by a cercosporin-containing supernatant without organic solvent extraction and purification after liquid fermentation. Thus we set up a bridge between microbial fermentation and organic photocatalysis for chemical reactions in a sustainable, environmentally friendly manner.
- Zhang, Shiwei,Tang, Zhaocheng,Bao, Wenhao,Li, Jia,Guo, Baodang,Huang, Shuping,Zhang, Yan,Rao, Yijian
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p. 4364 - 4369
(2019/05/10)
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- Mechanochemical Activation of Zinc and Application to Negishi Cross-Coupling
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A form independent activation of zinc, concomitant generation of organozinc species and engagement in a Negishi cross-coupling reaction via mechanochemical methods is reported. The reported method exhibits a broad substrate scope for both C(sp3)–C(sp2) and C(sp2)–C(sp2) couplings and is tolerant to many important functional groups. The method may offer broad reaching opportunities for the in situ generation organometallic compounds from base metals and their concomitant engagement in synthetic reactions via mechanochemical methods.
- Cao, Qun,Howard, Joseph L.,Wheatley, Emilie,Browne, Duncan L.
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supporting information
p. 11339 - 11343
(2018/08/28)
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- Electron-Catalyzed Cross-Coupling of Arylboron Compounds with Aryl Iodides
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Arylboroxines in combination with zinc chloride and potassium tert-butoxide were found to undergo the electron-catalyzed cross-coupling with aryl iodides to give the corresponding biaryls without the aid of transition-metal catalysis.
- Okura, Keisho,Teranishi, Tsuyoshi,Yoshida, Yuto,Shirakawa, Eiji
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supporting information
p. 7186 - 7190
(2018/06/15)
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- Development of highly electron-deficient and less sterically-hindered phosphine ligands possessing 1,3,5-triazinyl groups
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Highly electron-deficient and less sterically-hindered phosphine ligands with two or three 1,3,5-triazinyl groups on the phosphorus atoms have been synthesized and examined in transition metal-catalyzed reactions for the first time. Due to the lack of any hydrogens or substituents at ortho-positions of the 1,3,5-triazine towards the phosphorous atom, it is considered that the steric hindrance of the tris(triazinyl)phosphine ligand to a metal center is least among triarylphosphine ligands. In the Stille coupling of aryl iodides, these electron-poor phosphine ligands provided good product yields compared to hitherto well-known phosphine ligands.
- Abe, Kazumi,Kitamura, Masanori,Fujita, Hikaru,Kunishima, Munetaka
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- Palladacycles derived from arylphosphinamides for mild Suzuki-Miyaura cross-couplings
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We present a type of palladacyclic complexes derived from arylphosphinamides which can be used as efficient and versatile precatalysts for mild Suzuki-Miyaura cross-coupling. With the presence of 1.0 mol% of palladacycles, a wide variety of aryl bromides and boronic acids could be coupled very efficiently at ambient temperature and under air atmosphere without the need of external supporting ligands. Moreover, the mild conditions also allow for smooth coupling of electron-deficient, i.e., the less stable aryl triflates. In addition to the highly catalytic activity, the palladacyclic complexes can be very easily prepared through a two-step procedure from the readily affordable diphenyl-phosphinic chloride and exhibit excellent stability toward air and moisture. Due to these prominent properties, the new palladacycles would find practical use in Suzuki-Miyaura couplings.
- Wu, Guo-Jie,Han, Fu-She,Zhao, Yu-Long
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p. 69776 - 69781
(2015/09/01)
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- Light-Induced C-H Arylation of (Hetero)arenes by in Situ Generated Diazo Anhydrides
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Diazo anhydrides (Ar-N=N-O-N=N-Ar) have been known since 1896 but have rarely been used in synthesis. This communication describes the development of a photochemical catalyst-free C-H arylation methodology for the preparation of bi(hetero)aryls by the one-pot reaction of anilines with tert-butyl nitrite and (hetero)arenes under neutral conditions. The key step in this procedure is the in situ formation and subsequent photochemical (>300 nm) homolytic cleavage of a transient diazo anhydride intermediate. The generated aryl radical then efficiently reacts with a (hetero)arene to form the desired bi(hetero)aryls producing only nitrogen, water, and tert-butanol as byproducts. The scope of the reaction for several substituted anilines and (hetero)arenes was investigated. A continuous-flow protocol increasing selectivity and safety has been developed enabling the experimentally straightforward preparation of a variety of substituted bi(hetero)aryls within 45 min of reaction time.
- Cantillo, David,Mateos, Carlos,Rincon, Juan A.,De Frutos, Oscar,Kappe, C. Oliver
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supporting information
p. 12894 - 12898
(2015/09/07)
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- Efficient desulfinylative cross-coupling of thiophene and furan sulfinates with aryl bromides in aqueous media
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This letter describes the development of an environmentally benign palladium-catalyzed cross-coupling reaction using heteroaromatic sulfinates as nucleophilic coupling partners in aqueous media. This method accesses aryl-substituted heteroaromatics in very good yields chemoselectively without the need for base, additives or co-catalysts.
- Sévigny, Stéphane,Forgione, Pat
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supporting information
p. 589 - 592
(2013/04/10)
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- Palladium-catalyzed intermolecular desulfinylative cross-coupling of heteroaromatic sulfinates
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Beauty lies in simplicity: An efficient and environmentally benign palladium-catalyzed protocol has been developed using a sulfinate as a nucleophilic coupling partner. The sulfinate position is arylated chemoselectively in very good yields. The bench-stable, non-hygroscopic heteroaromatic sulfinate salts rapidly undergo cross-coupling without the need of a co-catalyst, base, or additives (see scheme; mw=microwave). Copyright
- Sévigny, Stéphane,Forgione, Pat
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supporting information
p. 2256 - 2260
(2013/03/28)
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- Cross-coupling of aryltrimethylammonium iodides with arylzinc reagents catalyzed by amido pincer nickel complexes
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The cross-coupling reaction of aryltrimethylammonium iodides with aryl- or heteroarylzinc chlorides catalyzed by amido pincer nickel complexes was performed. The reaction requires low catalyst loading and displays broad substrate scope.
- Zhang, Xue-Qi,Wang, Zhong-Xia
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experimental part
p. 3658 - 3663
(2012/05/20)
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- Metal-free, visible-light-mediated direct C-H arylation of heteroarenes with aryl diazonium salts
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Visible light along with 1 mol % eosin Y catalyzes the direct C-H bond arylation of heteroarenes with aryl diazonium salts by a photoredox process. We have investigated the scope of the reaction for several aryl diazonium salts and heteroarenes. The general and easy procedure provides a transition-metal-free alternative for the formation of aryl-heteroaryl bonds.
- Hari, Durga Prasad,Schroll, Peter,Koenig, Burkhard
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supporting information; experimental part
p. 2958 - 2961
(2012/04/04)
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- Cobalt-catalyzed preparation of arylindium reagents from aryl and heteroaryl bromides
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A cobalt-bathophenanthroline catalyst has been developed for the direct preparation of a variety of arylindium reagents from the corresponding aryl and heteroaryl bromides in the presence of indium metal and lithium chloride. The thus-formed arylindium reagents undergo efficient palladium-catalyzed cross-coupling reactions with aryl iodides, tolerating various functional groups including hydroxy and free amino groups.
- Adak, Laksmikanta,Yoshikai, Naohiko
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experimental part
p. 7563 - 7568
(2011/11/12)
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- Radical catalysis of kumada cross-coupling reactions using functionalized grignard reagents
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(Chemical Equation Presented) Palladium, radically different: A wide range of polyfunctional aryl- and heteroarylmagnesium reagents undergo fast Kumada cross-couplings (see scheme) with functionalized aryl bromides in the presence of a palladium catalyst and an alkyl iodide as additive. These reactions proceed by a radical pathway.
- Manolikakes, Georg,Knochel, Paul
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supporting information; experimental part
p. 205 - 209
(2009/04/10)
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- Silicon-Based Cross-Coupling Reagent and Production Method of Organic Compound Using the Same
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In one embodiment of the present invention, a silicon-based cross-coupling reagent is disclosed which is a highly stable tetraorganosilicon compound allowing for a cross-coupling reaction under mild reaction conditions without using fluoride ions, transition metal promoter, or strong bases, and the residue of the silicon reagent can be recovered and reused. The silicon-based cross-coupling reagent is a silicon compound in which an o-hydroxymethylphenyl group is connected to a silicon atom for intramolecular activation.
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Page/Page column 20
(2009/04/24)
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- Palladium-catalyzed cross-coupling of five-membered heterocyclic silanolates
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(Chemical Equation Presented) The preparation of π-rich 2-aryl heterocycles by palladium-catalyzed cross-coupling of sodium heteroarylsilanolates with aryl iodides, bromides, and chlorides is described. The cross-coupling process was developed through extensive optimization of the following key variables: (1) identification of stable, isolable alkali metal silanolates, (2) identification of conditions for preformation and isolation of silanolate salts, (3) judicious choice in the palladium catalyst/ligand combination, and (4) selection of the protecting group on the nitrogen of indole. It was found that the alkali metal silanolates, either isolated or formed in situ, offered a significant rate enhancement and broader substrate scope over the use of silanols activated by Bronsted bases such as NaOt-Bu. In addition, the optimized conditions for the cross-coupling of 2-indolylsilanolates were readily applied to the cross-coupling of 2-pyrrolyl-, 2-furyl-, and 2-thienylsilanolates.
- Denmark, Scott E.,Baird, John D.,Regens, Christopher S.
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p. 1440 - 1455
(2008/04/12)
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- Palladium-catalyzed cross-coupling reactions of heterocyclic silanolates with substituted aryl iodides and bromides
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Sodium silanolates derived from a number of heterocyclic silanols undergo cross-coupling with a variety of aromatic iodides and bromides under mild conditions. In situ deprotonation of the silanols with an equivalent amount of sodium hydride in toluene ge
- Denmark, Scott E.,Baird, John D.
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p. 793 - 795
(2007/10/03)
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- New efficient preparation of functionalized arylzinc or thienylzinc compounds from aryl or thienyl chlorides using cobalt catalysis
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A new chemical method is described for the preparation of aryl or thienyl zinc intermediates from their corresponding aromatic or thienyl chlorides in a mixture of acetonitrile-pyridine, using cobalt catalysis. This procedure allows for the synthesis of a
- Gosmini, Corinne,Amatore, Muriel,Claudel, Stéphanie,Périchon, Jacques
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p. 2171 - 2174
(2007/10/03)
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- Alkenyl- and aryl[2-(hydroxymethyl)phenyl]dimethylsilanes: An entry to tetraorganosilicon reagents for the silicon-based cross-coupling reaction
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Alkenyl- and aryl[2-(hydroxymethyl)phenyl]dimethylsilanes, highly stable tetraorganosilicon reagents, are found to react with aryl and alkenyl iodides in the presence of a palladium catalyst and K2CO3 as a base, significantly milder conditions compared with those ever reported for the silicon-based cross-coupling reactions. The reaction tolerates a wide range of functional groups, including silyl protectors, and allows a gram-scale synthesis to recover and reuse the silicon residue. Copyright
- Nakao, Yoshiaki,Imanaka, Hidekazu,Sahoo, Akhila K.,Yada, Akira,Hiyama, Tamejiro
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p. 6952 - 6953
(2007/10/03)
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- New carboxamide compounds having melanin concentrating hormone antagonistic activity, pharmaceutical preparations comprising these compounds and process for their manufacture
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The present invention relates to carboxamide compounds of general formula I wherein the groups and residues A, B, W, X, Y, Z, R1, R2, R3 and k have the meanings given in claim 1. Moreover the invention relates to process for preparing the above mentioned carboxamides as well as pharmaceutical compositions containing at least one carboxamide according to the invention. In view of their MCH-receptor antagonistic activity the pharmaceutical compositions according to the invention are suitable for the treatment of metabolic disorders and/or eating disorders, particularly obesity, bulimia, anorexia, hyperphagia and diabetes.
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Page/Page column 82
(2010/02/09)
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- An Unusual Sequence of Smectic Phases Formed by Members of the Homologous Series of 3-Fluoro-4-octyloxyphenyl 4-(5-Alkyl-2-thienyl)benzoates
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Nine 4-(5-n-alkyl-2-thienyl)benzoic acids have been converted into esters by reaction with 3-fluoro-4-n-octyloxyphenol.The liquid crystal properties of these esters have been investigated by thermal optical microscopy, differential scanning calorimetry, a
- Butcher, J. L.,Byron, D. J.,Shirazi, S. N. R.,Tajbakhsh, A. R.,Wilson, R. C.,Bunning, J. D.
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p. 327 - 343
(2007/10/02)
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