- Inhibition of (dppf)nickel-catalysed Suzuki-Miyaura cross-coupling reactions by α-halo-N-heterocycles
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A nickel/dppf catalyst system was found to successfully achieve the Suzuki-Miyaura cross-coupling reactions of 3- and 4-chloropyridine and of 6-chloroquinoline but not of 2-chloropyridine or of other α-halo-N-heterocycles. Further investigations revealed that chloropyridines undergo rapid oxidative addition to [Ni(COD)(dppf)] but that α-halo-N-heterocycles lead to the formation of stable dimeric nickel species that are catalytically inactive in Suzuki-Miyaura cross-coupling reactions. However, the corresponding Kumada-Tamao-Corriu reactions all proceed readily, which is attributed to more rapid transmetalation of Grignard reagents.
- Burton, Paul M.,Cooper, Alasdair K.,Donohoe, William,Greaves, Megan E.,Kennedy, Alan R.,Nelson, David J.,Ronson, Thomas O.
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p. 14074 - 14082
(2021/11/12)
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- A Proton-Responsive Pyridyl(benzamide)-Functionalized NHC Ligand on Ir Complex for Alkylation of Ketones and Secondary Alcohols
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A Cp*Ir(III) complex (1) of a newly designed ligand L1 featuring a proton-responsive pyridyl(benzamide) appended on N-heterocyclic carbene (NHC) has been synthesized. The molecular structure of 1 reveals a dearomatized form of the ligand. The protonation of 1 with HBF4 in tetrahydrofuran gives the corresponding aromatized complex [Cp*Ir(L1H)Cl]BF4 (2). Both compounds are characterized spectroscopically and by X-ray crystallography. The protonation of 1 with acid is examined by 1H NMR and UV-vis spectra. The proton-responsive character of 1 is exploited for catalyzing α-alkylation of ketones and β-alkylation of secondary alcohols using primary alcohols as alkylating agents through hydrogen-borrowing methodology. Compound 1 is an effective catalyst for these reactions and exhibits a superior activity in comparison to a structurally similar iridium complex [Cp*Ir(L2)Cl]PF6 (3) lacking a proton-responsive pendant amide moiety. The catalytic alkylation is characterized by a wide substrate scope, low catalyst and base loadings, and a short reaction time. The catalytic efficacy of 1 is also demonstrated for the syntheses of quinoline and lactone derivatives via acceptorless dehydrogenation, and selective alkylation of two steroids, pregnenolone and testosterone. Detailed mechanistic investigations and DFT calculations substantiate the role of the proton-responsive ligand in the hydrogen-borrowing process.
- Kaur, Mandeep,U Din Reshi, Noor,Patra, Kamaless,Bhattacherya, Arindom,Kunnikuruvan, Sooraj,Bera, Jitendra K.
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supporting information
p. 10737 - 10748
(2021/06/15)
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- A Highly Efficient Monophosphine Ligand for Parts per Million Levels Pd-Catalyzed Suzuki–Miyaura Coupling of (Hetero)Aryl Chlorides
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A new indolylphosphine WK-phos has been synthesized for Pd-catalyzed Suzuki–Miyaura coupling of (hetero)aryl chlorides with (alkyl)arylboronic acids. Comprising this newly developed ligand with palladium(II) acetate, the resulting catalyst system was found to be highly effective in facilitating the reaction even when the catalyst loading reaches parts per million levels (e.g. 10 ppm). These examples represent one of the lowest catalyst loadings reported to date of employing monophosphine (e.g. Ar-PCy2) for Suzuki–Miyaura reactions. The ligand geometry has also been well-characterized by single-crystal X-ray crystallography.
- Choy, Pui Ying,Yuen, On Ying,Leung, Man Pan,Chow, Wing Kin,Kwong, Fuk Yee
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p. 2846 - 2853
(2020/04/09)
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- Efficient Pd-Catalyzed Direct Coupling of Aryl Chlorides with Alkyllithium Reagents
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Organolithium compounds are amongst the most important organometallic reagents and frequently used in difficult metallation reactions. However, their direct use in the formation of C?C bonds is less established. Although remarkable advances in the coupling of aryllithium compounds have been achieved, Csp2?Csp3 coupling reactions are very limited. Herein, we report the first general protocol for the coupling or aryl chlorides with alkyllithium reagents. Palladium catalysts based on ylide-substituted phosphines (YPhos) were found to be excellently suited for this transformation giving high selectivities at room temperature with a variety of aryl chlorides without the need for an additional transmetallation reagent. This is demonstrated in gram-scale synthesis including building blocks for materials chemistry and pharmaceutical industry. Furthermore, the direct coupling of aryllithiums as well as Grignard reagents with aryl chlorides was also easily accomplished at room temperature.
- Dilchert, Katharina,Gessner, Viktoria H.,Gro?johann, Angela,Rodstein, Ilja,Scherpf, Thorsten,Steinert, Henning,Tappen, Jens
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supporting information
p. 20596 - 20603
(2020/09/09)
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- Double Hydroboration of Quinolines via Borane Catalysis: Diastereoselective One Pot Synthesis of 3-Hydroxytetrahydroquinolines
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Described herein is an organoborane-catalysed consecutive borylative reduction of quinolines and isoquinolines to furnish tetrahydro(iso)quinolines bearing a C(sp3)?B bond β to the nitrogen atom. The installed C?B bond is oxidatively transformed to the hydroxy group in one pot. The present double hydroboration is proposed to proceed via a stepwise ionic mechanism involving a boronium ion. The stereo-outcome was found to be dependent on the position (C2 vs C4) of the substituents in quinolines. (Figure presented.).
- Kim, Eunae,Jeon, Hyun Ji,Park, Sehoon,Chang, Sukbok
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supporting information
p. 308 - 313
(2019/11/13)
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- Iridium/Acid Cocatalyzed Direct Access to Fused Indoles via Transfer Hydrogenative Annulation of Quinolines and 1,2-Diketones
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Herein, we present an unprecedented iridium/acid cocatalyzed construction of fused indoles via transfer hydrogenative annulation of nonactivated quinolines and 1,2-diketones. The products are assembled via initial reduction followed by selective coupling
- Jiang, Huanfeng,Lu, Guangpeng,Xie, Feng,Xie, Rong,Zhang, Min
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supporting information
p. 2308 - 2312
(2020/04/09)
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- Ni: Vs. Pd in Suzuki-Miyaura sp2-sp2 cross-coupling: A head-to-head study in a comparable precatalyst/ligand system
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The Suzuki-Miyaura reaction is a cornerstone method for sp2-sp2 cross-coupling in industry. There has been a concerted effort to enable the use of Ni catalysis as an alternative to Pd in order to mitigate cost and improve sustainability. Despite significant advances, ligand development for Ni-catalyzed Suzuki-Miyaura cross-coupling remains underdeveloped when compared to Pd and, as a consequence, ligands for Ni-catalyzed processes are typically taken from the Pd arena. In this study we evaluate the effect of using a similar Ni and Pd precatalyst based on a common bidentate ligand (dppf) in a head-to-head format for the most common type of biaryl couplings, establishing the practical implications of direct replacement of Pd with Ni, and identifying the potential origins of these observations in a mechanistic context.
- West, Matthew J.,Watson, Allan J. B.
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supporting information
p. 5055 - 5059
(2019/06/03)
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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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- Cobalt-Catalyzed Cross-Coupling Reactions of Arylboronic Esters and Aryl Halides
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An efficient cobalt catalyst system for the Suzuki-Miyaura cross-coupling reaction of arylboronic esters and aryl halides has been identified. In the presence of cobalt(II)/terpyridine catalyst and potassium methoxide, a diverse array of (hetero)biaryls have been prepared in moderate to excellent yields.
- Duong, Hung A.,Wu, Wenqin,Teo, Yu-Yuan
-
supporting information
p. 4363 - 4366
(2017/12/05)
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- Revisitation of Organoaluminum Reagents Affords a Versatile Protocol for C-X (X = N, O, F) Bond-Cleavage Cross-Coupling: A Systematic Study
-
A revisit of organoaluminum reagents for cross-coupling reactions has opened up several types of C-C bond formation protocols through cleavage of phenolic/alcoholic C-O and C-F and ammonium C-N bonds. Catalyzed by the commercially available NiCl2(PCy3)2 catalyst, these reactions proceed smoothly with a wide range of substrates and broad functional group compatibility, providing a versatile methodology for organoaluminum-mediated cross-coupling processes.
- Ogawa, Hiroyuki,Yang, Ze-Kun,Minami, Hiroki,Kojima, Kumiko,Saito, Tatsuo,Wang, Chao,Uchiyama, Masanobu
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p. 3988 - 3994
(2017/06/19)
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- From Anilines to Quinolines: Iodide- and Silver-Mediated Aerobic Double C?H Oxidative Annulation–Aromatization
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Quinoline synthesis from easily accessible raw materials such as anilines is a valuable and meaningful task. Herein, we communicate an iodide- and silver-mediated C?H/C?H oxidative annulation–aromatization between anilines and allyl alcohols. This protocol provides a direct route to the synthesis of quinoline derivatives from inexpensive commodities. Various kinds of anilines, even heterocyclic anilines, were shown to be workable substrates, generating the corresponding multi-substituted quinolines in good yields.
- Wu, Jiwei,Liao, Zhixiong,Liu, Dong,Chiang, Chien-Wei,Li, Zheng,Zhou, Zhonghao,Yi, Hong,Zhang, Xu,Deng, Zixin,Lei, Aiwen
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supporting information
p. 15874 - 15878
(2017/10/23)
-
- Inhibitors of the detoxifying enzyme of the phytoalexin brassinin based on quinoline and isoquinoline scaffolds
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The detoxification of the phytoalexin brassinin to indole-3-carboxaldehyde and S-methyl dithiocarbamate is catalyzed by brassinin oxidase (BOLm), an inducible fungal enzyme produced by the plant pathogen Leptosphaeria maculans. Twenty-six substituted quinolines and isoquinolines are synthesized and evaluated for antifungal activity against L. maculans and inhibition of BOLm. Eleven compounds that inhibit BOLm activity are reported, of which 3-ethyl-6-phenylquinoline displays the highest inhibitory effect. In general, substituted 3-phenylquinolines show significantly higher inhibitory activities than the corresponding 2-phenylquinolines. Overall, these results indicate that the quinoline scaffold is a good lead to design paldoxins (phytoalexin detoxification inhibitors) that inhibit the detoxification of brassinin by L. maculans.
- Pedras, M. Soledade C.,Abdoli, Abbas,Sarma-Mamillapalle, Vijay K.
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- Chemoselective One-Pot Synthesis of Functionalized Amino-azaheterocycles Enabled by COware
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Functionalized bicyclic amino-azaheterocycles are rapidly accessed in a one-pot cross-coupling/reduction sequence enabled by the use of COware. Incompatible reagents are physically separated in a single reaction vessel to effect two chemoselective transformations - Suzuki-Miyaura cross-coupling and heteroarene reduction. The developed method allows access to novel heterocyclic templates, including semisaturated Hedgehog and dual PI3K/mTOR inhibitors, which show enhanced physicochemical properties compared to their unsaturated counterparts.
- Clohessy, Thomas A.,Roberts, Alastair,Manas, Eric S.,Patel, Vipulkumar K.,Anderson, Niall A.,Watson, Allan J. B.
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supporting information
p. 6368 - 6371
(2017/12/08)
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- Pd-Catalyzed Ligand-Free Synthesis of Arylated Heteroaromatics by Coupling of N-Heteroaromatic Bromides with Iodobenzene Diacetate, Iodosobenzene, or Diphenyliodonium Salts
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An efficient method for synthesizing arylated heteroaromatics has been reported via Pd-catalyzed ligand-free cross-coupling of N-heteroaromatic bromides with iodine(III) reagents under mild conditions. Iodobenzene diacetate, iodosobenzene, and diphenyliod
- Wang, Xiajun,He, Yongqin,Ren, Mengdan,Liu, Shengkang,Liu, He,Huang, Guosheng
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p. 7958 - 7962
(2016/09/09)
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- A General Palladium-Catalyzed Hiyama Cross-Coupling Reaction of Aryl and Heteroaryl Chlorides
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A general palladium-catalyzed Hiyama cross-coupling reaction of aryl and heteroaryl chlorides with aryl and heteroaryl trialkoxysilanes by a Pd(OAc)2/L2 catalytic system is presented. A newly developed water addition protocol can dramatically improve the product yields. The conjugation of the Pd/L2 system and the water addition protocol can efficiently catalyze a broad range of electron-rich, -neutral, -deficient, and sterically hindered aryl chlorides and heteroaryl chlorides with excellent yields within three hours and the catalyst loading can be down to 0.05 mol % Pd for the first time. Hiyama coupling of heteroaryl chlorides with heteroaryl silanes is also reported for the first time. The reaction can be easily scaled up 200 times (100 mmol) without any degasification and purification of reactants; this facilitates the practical application in routine synthesis.
- Yuen, On Ying,So, Chau Ming,Man, Ho Wing,Kwong, Fuk Yee
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supporting information
p. 6471 - 6476
(2016/05/09)
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- General copper-catalyzed coupling of alkyl-, aryl-, and alkynylaluminum reagents with organohalides
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We report the first example of a very general Cu-catalyzed cross-coupling of organoaluminum reagents with organohalides. The reactions proceed for the couplings of alkyl-, aryl-, and alkynylaluminum reagents with aryl and heteroaryl halides and vinyl bromides, affording the cross-coupled products in good to excellent yields. Both primary and secondary alkylaluminum reagents can be utilized as organometallic coupling partners. These reactions are not complicated by β-hydride elimination, and as a result rearranged products are not observed with secondary alkylaluminum reagents even for couplings with heteroaryl halides under "ligand-free" conditions. Radical clock experiment with a radical probe and relative reactivity study of Ph3Al with two haloarenes, 1-bromonaphthalene and 4-chlorobenzonitrile, having two different redox potentials indicates that the reaction does not involve free aryl radicals and radical anions as intermediates. These results combined with the result of the Hammett plot obtained by reacting Ph3Al with iodoarenes containing p-H, p-Me, p-F, and p-CF3 substituents, which shows a linear curve (R2 = 0.99) with a ρ value of +1.06, suggest that the current transformation follows an oxidative addition-reductive elimination pathway.
- Shrestha, Bijay,Thapa, Surendra,Gurung, Santosh K.,Pike, Ryan A. S.,Giri, Ramesh
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p. 787 - 802
(2016/02/18)
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- A novel protocol for the one-pot borylation/Suzuki reaction provides easy access to hinge-binding groups for kinase inhibitors
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The one-pot borylation/Suzuki reaction is a very efficient means of accessing cross-coupling products of two aryl-halide partners that generally requires the use of specific catalysts or ligands and/or relatively long reaction times. This new microwave-assisted method provides a quick one-pot borylation/Suzuki reaction protocol that we applied to the synthesis of various bi- or poly-aryl scaffolds, including a variety of aryl and heteroaryl ring systems and the core frameworks of kinase inhibitors vemurafenib and GDC-0879.
- Hooper,Zambon,Springer
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p. 963 - 969
(2016/01/15)
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- Organocatalytic Stereoselective Addition of Aldehydes to Acylquinolinium Ions
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A direct and simple activation of quinolines, without isolating unstable intermediates, or using isolated N,O-acetals in the presence of Lewis or Br?nsted acids, is described. The procedure is quite straightforward and allows the addition in a stereoselective manner of different aldehydes to various differently substituted quinolines. The desired products were obtained in 28–76 % yields, with dr values up to 83:17 in favor of the syn isomer, and up to 99 % ee. Studies towards the use of acetaldehyde were also performed with different catalysts and the addition was promoted affording the desired product in 62 % yield with 46 % ee. Finally, deprotection and chemical transformations of the enantioenriched adducts were performed.
- Mengozzi, Luca,Gualandi, Andrea,Cozzi, Pier Giorgio
-
supporting information
p. 3200 - 3207
(2016/07/19)
-
- Rhodium-catalyzed cross-coupling of aryl carbamates with arylboron reagents
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A new method has been developed for the rhodium-catalyzed cross-coupling of aryl carbamates with organoboron reagents. The use of an NHC ligand bearing a 2-adamantyl group, i.e., I(2-Ad), is essential to the success of the reaction. The reaction involves the rhodium-mediated activation of the relatively inert C(aryl)-O bond of aryl carbamates.
- Nakamura, Keisuke,Yasui, Kosuke,Tobisu, Mamoru,Chatani, Naoto
-
supporting information
p. 4484 - 4489
(2015/03/30)
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- Single-electron-transfer-induced coupling of arylzinc reagents with aryl and alkenyl halides
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Arylzinc reagents, prepared from aryl halides/zinc powder or aryl Grignard reagents/zinc chloride, were found to undergo coupling with aryl and alkenyl halides without the aid of transition-metal catalysis to give biaryls and styrene derivatives, respectively. In this context, we have already reported the corresponding reaction using aryl Grignard reagents instead of arylzinc reagents. Compared with the Grignard cross-coupling, the present reaction features high functional-group tolerance, whereby electrophilic groups such as alkoxycarbonyl and cyano groups are compatible as substituents on both the arylzinc reagents and the aryl halides. Aryl halides receive a single electron and thereby become activated as the corresponding anion radicals, which react with arylzinc reagents, thus leading to the cross-coupling products. Arylzinc reagents were found to undergo coupling with aryl and alkenyl halides to give biaryl and styrene derivatives, respectively. The cross-coupling, which features high functional-group tolerance, proceeds through a single-electron-transfer mechanism and thus does not require the aid of transition-metal catalysis.
- Shirakawa, Eiji,Tamakuni, Fumiko,Kusano, Eugene,Uchiyama, Nanase,Konagaya, Wataru,Watabe, Ryo,Hayashi, Tamio
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p. 521 - 525
(2014/01/23)
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- PLATINUM COMPOUNDS, COMPOSITIONS AND METHODS FOR THE TREATMENT OF CANCER
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The present disclosure relates to novel pharmaceutical compositions comprising a nanoparticle associated with, tether to, or encapsulating a platinum-based active pharmaceutical agent. The platinum-based drug is released from the nanoparticles in a controlled fashion. Also contemplated are methods of making the nanoparticles, as well as methods for using them in the treatment or prevention of diseases or conditions. One embodiment relates to phenanthriplatin nanoparticles and methods of using and making the same.
- -
-
Paragraph 00232
(2014/04/03)
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- Room-temperature photoinduced direct C-H-arylation via base-promoted homolytic aromatic substitution
-
Conceptually different approach toward biaryl syntheses by photoinduced direct C-H arylation of benzene and thiophene in the presence of t-BuOK is reported. The reaction proceeds through photo- and base-promoted homolytic aromatic substitution. The o-, m- and p- substituted ArI, as well as the electron-donating and electron-withdrawing nature of the substituents were found be good to excellent substrates. Heteroaryl, ArBr, ArCl and double C-H arylation were successfully achieved.
- Budén, María E.,Guastavino, Javier F.,Rossi, Roberto A.
-
supporting information
p. 1174 - 1177
(2013/04/24)
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- Room-temperature Suzuki-Miyaura coupling of heteroaryl chlorides and tosylates
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Suzuki-Miyaura coupling of heteroaryls is an important method for the preparation of compound libraries for medicinal chemistry and materials research. Although many catalysts have been developed, none of them have been generally applicable to the coupling reactions of heteroaryl chlorides and tosylates at room temperature. We discovered that a catalyst combination of Pd(OAc)2 and XPhos (2-dicyclohexylphosphanyl-2',4',6'- triisopropylbiphenyl) could efficiently catalyze these couplings. Besides the choice of catalyst, the use of hydroxide bases in an aqueous alcoholic solvent was essential for fast couplings. These conditions promoted fast release of active catalyst (XPhos)Pd0, and accelerated the transmetalation in the catalytic cycle. Most of the major families of heteroaryl chlorides (31 examples) and tosylates (17 examples) reached full conversion within minutes to hours at room temperature. The method could be easily scaled up for gram-scale synthesis. Furthermore, we examined the relative reactivity of coupling partners in whole reactions. Electron-rich heteroaryl chlorides and tosylates reacted more slowly than electron-deficient ones, in the order of indole, pyrrole furan, thiophene > pyridine. Similarly, electron-deficient arylboronic acids were less reactive than electron-neutral and electron-rich ones. The reactivity trends from this study can help to choose appropriate coupling partners for Suzuki reactions.
- Yang, Junfeng,Liu, Sijia,Zheng, Jian-Feng,Zhou, Jianrong
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supporting information
p. 6248 - 6259,12
(2020/09/16)
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- IRIDIUM COMPLEX COMPOUND, ORGANIC ELECTROLUMINESCENCE ELEMENT, AND USE THEREFOR
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It is an object of the present invention to provide a red phosphorescent compound having a high emission quantum yield, which is used for producing organic EL elements. The red phosphorescent compound of the present invention is an iridium complex compound represented by the following formula (1). In the formula (1), L1 is selected from the following formulas (2) and (3).
- -
-
Page/Page column 24-25
(2012/10/18)
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- A cyclobutene-1,2-bis(imidazolium) salt as preligand for palladium-catalyzed cross-coupling reactions: Properties and applications
-
Spectroscopic investigations and the results of calculations on the title bis-imidazolium salt, its mono-and bis-carbenes, and its interactions with palladium are presented. In addition, we report on the scope and limitations of metal-catalyzed cross-coupling reactions performed with the title bis-imidazolium salt. The salt proved to be an efficient ligand precursor in room-temperature Suzuki-Miyaura reactions, C-C couplings with sterically extremely hindered biaryls,selective thiophene arylations, and couplings with vinylic chlorides. Spectroscopic investigations and the results of calculations on the title bis-imidazolium salt, its mono-and bis-carbenes, and its interactions with palladium are presented. In addition, we report on the scope and limitations of metal-catalyzed cross-coupling reactions performed with the title bis-imidazolium salt. Copyright
- Rahimi, Alireza,Papai, Imre,Madarasz, Udam,Gjikaj, Mimoza,Namyslo, Jan C.,Schmidt, Andreas
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experimental part
p. 754 - 763
(2012/03/12)
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- Suzuki-Miyaura cross-coupling of aryl carbamates and sulfamates: Experimental and computational studies
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The first Suzuki-Miyaura cross-coupling reactions of the synthetically versatile aryl O-carbamate and O-sulfamate groups are described. The transformations utilize the inexpensive, bench-stable catalyst NiCl 2(PCy3)2 to furnish biaryls in good to excellent yields. A broad scope for this methodology has been demonstrated. Substrates with electron-donating and electron-withdrawing groups are tolerated, in addition to those that possess ortho substituents. Furthermore, heteroaryl substrates may be employed as coupling partners. A computational study providing the full catalytic cycles for these cross-coupling reactions is described. The oxidative addition with carbamates or sulfamates occurs via a five-centered transition state, resulting in the exclusive cleavage of the aryl C-O bond. Water is found to stabilize the Ni-carbamate catalyst resting state, which thus provides rationalization of the relative decreased rate of coupling of carbamates. Several synthetic applications are presented to showcase the utility of the methodology in the synthesis of polysubstituted aromatic compounds of natural product and bioactive molecule interest.
- Quasdorf, Kyle W.,Antoft-Finch, Aurora,Liu, Peng,Silberstein, Amanda L.,Komaromi, Anna,Blackburn, Tom,Ramgren, Stephen D.,Houk,Snieckus, Victor,Garg, Neil K.
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supporting information; experimental part
p. 6352 - 6363
(2011/06/19)
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- Well-defined air-stable palladium HASPO complexes for efficient Kumada-Corriu cross-couplings of (Hetero)aryl or alkenyl tosylates
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Palladium complexes of representative heteroatom-substituted secondary phosphine oxide (HASPO) preligands were synthesized and fully characterized, including X-ray crystal structure analysis. Importantly, these well-defined complexes served as highly efficient catalysts for Kumada-Corriu cross-coupling reactions of aryl, alkenyl, and even heteroaryl tosylates. Particularly, an air-stable catalyst derived from inexpensive PinP(O)H displayed a remarkably high catalytic efficacy, which resulted in cross-couplings at low catalyst loadings under exceedingly mild reaction conditions with ample scope.
- Ackermann, Lutz,Kapdi, Anant R.,Fenner, Sabine,Kornhaab, Christoph,Schulzke, Carola
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supporting information; experimental part
p. 2965 - 2971
(2011/05/05)
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- Nickel-catalyzed efficient and practical Suzuki-Miyaura coupling of alkenyl and aryl carbamates with aryl boroxines
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(Figure Presented) Suzuki-Miyaura coupling of unactivated alkenyl carbamates Is described to construct polysubstituted olefins. The developed process is also suitable for heteroaromatic and even electron-rich aromatic carbamates.
- Xu, Li,Li, Bi-Jie,Wu, Zhen-Hua,Lu, Xing-Yu,Guan, Bing-Tao,Wang, Bi-Qin,Zhao, Ke-Qing,Shi, Zhang-Jie
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supporting information; experimental part
p. 884 - 887
(2010/04/29)
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- Palladium-indolylphosphine-catalyzed hiyama cross-coupling of aryl mesylates
-
(Chemical Equation Presented) Aryl mesylates are found to be applicable as electrophiles in organosilicon-mediated coupling reactions. The catalyst system comprising 2 mol % of Pd(OAc)2 and CM-phos supporting ligand is highly effective in catalyzing Hiyama cross-coupling of various aryl and heteroaryl mesylates. Interesting acid additive effects show that the presence of 0.25-0.50 equiv of acetic acid efficiently suppresses the mesylate decomposition and generally promotes the coupling product yields.
- So, Chau Ming,Lee, Hang Wai,Lau, Chak Po,Kwong, Fuk Yee
-
supporting information; experimental part
p. 317 - 320
(2009/07/04)
-
- Palladium-catalyzed Stille cross-coupling reaction of aryl chlorides using a pre-milled palladium acetate and XPhos catalyst system
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A highly active catalyst system based upon a biaryl monophosphine ligand, XPhos, for the palladium-catalyzed Stille reaction has been developed. This method allows for the coupling of aryl chlorides with a range of tributylarylstannanes to produce the corresponding biaryl compounds in good to excellent yields (61-98%) in short reaction times (4 h). Palladium(II) acetate [Pd(OAc)2] and XPhos in a 1:1.1 ratio were milled into a fine powder that was used as pre-catalyst for these reactions.
- Naber, John R.,Buchwald, Stephen L.
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supporting information; experimental part
p. 957 - 961
(2009/05/26)
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- Air-stable and highly active dendritic phosphine oxide-stabilized palladium nanoparticles: Preparation, characterization and applications in the carbon-carbon bond formation and hydrogenation reactions
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Dendrimer-stabilized palladium nanoparticles were formed in the reduction of palldium bis-(acetylacetonate) [Pd(acac)2] in the presence of phosphine dendrimer ligands using hydrogen in tetrahydrofuran. The resulting Pd nanoparticles were characterized by TEM, 31P NMR and 31P MAS NMR. The results indicated that the dendritic phosphine ligandswere oxidized to phosphine oxides. These dendrimer-stabilized Pd nanoparticles were demonstrated to be efficient catalysts for Suzuki and Stille coupling reactionsand hydrogenations. The dendritic wedges served as a stabilizer for keeping the nanoparticlesfrom aggregating, and asa vehicle for facilitating the separation and/or the recycling of the Pd catalyst. In the case of the Suzuki coupling reaction, these Pd nanoparticles exhibited high catalytic efficiency (TON up to 65,000) and air stability as compared with the commonly used homogeneous catalyst tetrakis(triphenylphosphine)palladium [Pd-(PPh 3)4]. In addition, the results obtained from the bulky dendritic substrate suggest that the Pd nanoparticles might act asres ervoir of catalytically active species, and that the reaction is actually catalyzed by the soluble Pd(0) and/or Pd(II) species leached from the nanoparticle surface.
- Wu, Lei,Li, Zhi-Wei,Zhang, Feng,He, Yan-Mei,Fan, Qing-Hua
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experimental part
p. 846 - 862
(2009/05/07)
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- A general palladium-catalyzed Suzuki-Miyaura coupling of aryl mesylates
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(Chemical Equation Presented) Catalyze this! The first palladium-catalyzed Suzuki-Miyaura coupling of unactivated aryl mesylates is reported, with not only arylboronic acids, but also other organoboron nucleophiles (see picture; Z=B(OH)2, BF3K, BPin). The reaction conditions are compatible with various common functional groups (R1=alkyl, OMe, CHO, CO, CN, CO2R′, heteroaryl).
- So, Chau Ming,Lau, Chak Po,Kwong, Fuk Yee
-
supporting information; experimental part
p. 8059 - 8063
(2009/04/13)
-
- Suzuki-Miyaura coupling of aryl tosylates catalyzed by an array of indolyl phosphine-palladium catalysts
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A family of indolyl phosphine ligands was applied to Suzuki-Miyaura cross-coupling of aryl tosylates. Catalyst loading can be reduced to 0.2 mol % for coupling of nonactivated aryl tosylate. A challenging example for room temperature coupling is realized. The scope of this highly active Pd/L2 system can be extended to other boron nucleophiles, including trifluoroborate salts and boronate esters. The ligand structural comparisons toward the reactivity in tosylate couplings are also described.
- So, Chau Ming,Lau, Chak Po,Chan, Albert S. C.,Kwong, Fuk Yee
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p. 7731 - 7734
(2008/12/22)
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- Phosphine dendrimer-stabilized palladium nanoparticles, a highly active and recyclable catalyst for the Suzuki-Miyaura reaction and hydrogenation
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Phosphine dendrimer-stabilized palladium nanoparticles were synthesized and found to be highly effective for Suzuki coupling reactions, affording good to excellent product yields, high turnover number (up to 65 000), and excellent reusability (up to 9 catalytic runs). Furthermore, these Pd nanoparticles are efficient and selective catalysts for hydrogenations.
- Wu, Lei,Li, Bao-Lin,Huang, Yi-Yong,Zhou, Hai-Feng,He, Yan-Mei,Fan, Qing-Hua
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p. 3605 - 3608
(2007/10/03)
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- Cross-coupling of triallyl(aryl)silanes with aryl bromides and chlorides: An alternative convenient biaryl synthesis
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Cross-coupling of a diverse range of aryl bromides with triallyl(aryl)silanes is effective in the presence of PdCl2/PCy 3 and tetrabutylammonium fluoride (TBAF) in DMSO-H2O to give various biaryls in good yields. It is worthwhile to note that the all-carbon-substituted arylsilanes, stable towards moisture, acid, and base and easily accessible, serve as a highly practical alternative to their aryl(halo)silane counterparts. A catalyst system consisting of [η3-C3H5)PdCl]2 and 2-[2,4,6-(i-Pr)3C6Ha]-C6H4PCy 2 and use of TBAF· 3 H2O in THF-H2O are effective especially for the cross-coupling with aryl chlorides. Both of the catalyst systems tolerate a broad spectrum of common functional groups. The high efficiency of reactions is presumably due to the ready cleavage of the allyl groups upon treatment with TBAF·3 H2O and an appropriate amount of water. Diallyl(diphenyl)silane also cross-couples with various aryl bromides and chlorides in good yields, whereas allyl(triphenyl)silane gives the cross-coupled products in only moderate yields. Through sequential cross-coupling of bromochlorobenzenes with different arylsilanes, a range of unsymmetrical terphenyls are accessible in good overall yields.
- Sahoo, Akhila K.,Oda, Takuro,Nakao, Yoshiaki,Hiyama, Tamejiro
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p. 1715 - 1727
(2007/10/03)
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- Palladium Charcoal-Catalyzed Suzuki-Miyaura Coupling to Obtain Arylpyridines and Arylquinolines
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A phosphine ligand, such as PPh3 or 2-(dicyclohexylphosphino)biphenyl, is essential for the Pd/C-catalyzed Suzuki-Miyaura coupling of halopyridines and haloquinolines, although it has been reported that the reaction of phenyl chlorides can be catalyzed by nonprereduced Pd/C without any additives. In the reactions of bromopyridines, bromoquinolines, 2-chloropyridines, and 2-chloroquinolines, PPh3 was effective enough to provide coupling products in good yields. However, in the reactions of 3-chloropyridine, 4-chloropyridine, and 6-chloroquinoline, sterically hindered 2-(dicyclohexylphosphino)biphenyl was indispensable as a ligand.
- Tagata, Tsuyoshi,Nishida, Mayumi
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p. 9412 - 9415
(2007/10/03)
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