- Cobalt-Catalyzed Suzuki Biaryl Coupling of Aryl Halides
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Readily accessed cobalt pre-catalysts with N-heterocyclic carbene ligands catalyze the Suzuki cross-coupling of aryl chlorides and bromides with alkyllithium-activated arylboronic pinacolate esters. Preliminary mechanistic studies indicate that the cobalt
- Asghar, Soneela,Tailor, Sanita B.,Elorriaga, David,Bedford, Robin B.
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- A mild and ligand-free Ni-catalyzed silylation via C-OMe cleavage
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Metal-catalyzed transformations that forge carbon-heteroatom bonds are of central importance in organic synthesis. Despite the formidable potential of aryl methyl ethers as coupling partners, the scarcity of metal-catalyzed C-heteroatom bond formations via C-OMe cleavage is striking, with isolated precedents requiring specialized, yet expensive, ligands, high temperatures, and π-extended backbones. We report an unprecedented catalytic ipso-silylation of aryl methyl ethers under mild conditions and without recourse to external ligands. The method is distinguished by its wide scope, which includes the use of benzyl methyl ethers, vinyl methyl ethers, and unbiased anisóle derivatives, thus representing a significant step forward for designing new C-heteroatom bond formations via C-OMe scission. Applications of this transformation in orthogonal silylation techniques as well as in further derivatizations are also described. Preliminary mechanistic experiments suggest the intermediacy of Ni(0)-ate complexes, leaving some doubt that a canonical catalytic cycle consisting of an initial oxidative addition of the C-OMe bond to Ni(0) species comes into play.
- Zarate, Cayetana,Nakajima, Masaki,Martin, Ruben
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- Chiral Benzothiophene Synthesis via Enantiospecific Coupling of Benzothiophene S-Oxides with Boronic Esters
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Benzothiophenes are valuable heterocycles that are widely used in medicines, agrochemicals, and materials science. Herein, we report a general method for the synthesis of enantioenriched 2,3-disubstituted benzothiophenes via a transition-metal-free C2-alkylation of benzothiophenes with boronic esters. The reactions utilize benzothiophene S-oxides in lithiation-borylations to generate intermediate arylboronate complexes, and subsequent Tf2O-promoted S?O bond cleavage to trigger a Pummerer-type 1,2-metalate shift, which gives the coupled products with complete enantiospecificity. Primary, secondary and tertiary alkyl boronic esters and aryl boronic esters are successfully coupled with a range of C3-substituted benzothiophenes. Importantly, this transformation does not require the use of C3 directing groups, therefore it overcomes a major limitation of previously developed transition-metal-mediated C2 alkylations of benzothiophenes.
- Aggarwal, Varinder K.,Noble, Adam,Sang, Ruocheng
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supporting information
p. 25313 - 25317
(2021/11/09)
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- C3-Arylation of indoles with aryl ketonesviaC-C/C-H activations
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C3-Arylation of indoles with aryl ketones is accomplishedviapalladium-catalyzed ligand-promoted Ar-C(O) cleavage and subsequent C-H arylation of indole. Various (hetero)aryl ketones are compatible in this reaction, affording the corresponding 3-arylindoles in moderate to good yields. Further introduction of an indole moiety into the natural products desoxyestrone and evodiamine demonstrate the synthetic utility of this protocol.
- Dai, Hui-Xiong,Guo, Zi-Qiong,Ma, Biao,Wang, Xing,Wang, Zhen-Yu,Xu, Hui
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supporting information
p. 9716 - 9719
(2021/09/30)
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- Infrared Irradiation-Assisted Solvent-Free Pd-Catalyzed (Hetero)aryl-aryl Coupling via C?H Bond Activation
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The increasing attention towards environmentally friendly synthetic protocols has boosted studies directed to the development of green and sustainable methods for direct C?H bond arylation of (hetero)arenes. In this context, here the infrared (IR) irradia
- Albano, Gianluigi,Decandia, Gianfranco,Capozzi, Maria Annunziata M.,Zappimbulso, Nicola,Punzi, Angela,Farinola, Gianluca M.
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p. 3391 - 3401
(2021/07/28)
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- Tris-NHC-propagated self-supported polymer-based Pd catalysts for heterogeneous C-H functionalization
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Three-dimensionally propagated imidazolium-containing mesoporous coordination polymer and organic polymer-based platforms were successfully exploited to develop single-site heterogenized Pd-NHC catalysts for oxidative arene/heteroarene C-H functionalization reactions. The catalysts were efficient in directed arene halogenation, and nondirected arene and heteroarene arylation reactions. High catalytic activity, excellent heterogeneity and recyclability were offered by these systems making them promising candidates in the area of heterogeneous C-H functionalization, where efficient catalysts are still scarce.
- Choudhury, Joyanta,Dutta, Tapas Kumar,Mandal, Tanmoy,Mohanty, Sunit
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supporting information
p. 10182 - 10185
(2021/10/12)
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- Nickel-Catalyzed Asymmetric Hydrogenation of Cyclic Alkenyl Sulfones, Benzo[ b]thiophene 1,1-Dioxides, with Mechanistic Studies
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A highly efficient catalytic system based on the cheap transition metal nickel for the asymmetric hydrogenation of challenging cyclic alkenyl sulfones, 3-substituted benzo[b]thiophene 1,1-dioxides, was first successfully developed. A series of hydrogenation products, chiral 2,3-dihydrobenzo[b]thiophene 1,1-dioxides, were obtained in high yields (95-99%) with excellent enantioselectivities (90-99% ee). According to the results of nonlinear effect studies, deuterium-labeling experiments, and DFT calculation investigations, a reasonable catalytic mechanism for this nickel-catalyzed asymmetric hydrogenation was provided, which displayed that the two added hydrogen atoms of the hydrogenation products could be from H2 through the insertion of Ni-H and subsequent hydrogenolysis.
- Liu, Gongyi,Tian, Kui,Li, Chenzong,You, Cai,Tan, Xuefeng,Zhang, Heng,Zhang, Xumu,Dong, Xiu-Qin
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supporting information
p. 668 - 675
(2021/02/06)
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- Room Temperature C-H Arylation of Benzofurans by Aryl Iodides
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A robust method of room temperature direct arylation for benzofuran is reported. This discovery allows for mild arylation by commercially available aryl iodides with complete C-2 regioselectivity and tolerates a range of functional groups, including heat sensitive groups. Mechanistically, a Heck-type oxyarylation product from a direct arylation process is reported as a key piece of evidence for a carbopalladation intermediate.
- Mayhugh, Amy L.,Luscombe, Christine K.
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supporting information
p. 7079 - 7082
(2021/09/18)
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- Synthesis of benzofurans from the cyclodehydration of α-phenoxy ketones mediated by Eaton’s reagent
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Cyclodehydration of α-phenoxy ketones promoted by Eaton’s reagent (phosphorus pentoxide–methanesulfonic acid) is used to prepare 3-substituted or 2,3-disubstituted benzofurans with moderate to excellent yields under mild conditions. The method provides a facile access to benzofurans from readily available starting materials such as phenols and α-bromo ketones. The reaction is highly efficient, which is attributed to the good reactivity and fluidity of Eaton’s reagent. The reaction can be applied to prepare naphthofurans, furanocoumarins, benzothiophenes, and benzopyrans.
- Ma, Lin,Ma, Zhanwei,Zhang, Min,Zhou, Min
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p. 426 - 436
(2020/03/23)
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- Direct Arylations of Heteroarenes with Benzenesulfonyl Chlorides Using Pd/C Catalyst
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The reactivity of heteroaromatics in direct arylation with benzenesulfonyl chlorides using 10 % Pd/C as catalyst was explored. With (benzo)thiophenes, (benzo)furans, pyrroles and selenophenes, high yields in arylated heteroarenes were obtained. These arylations were performed using only 5 mol-% Pd/C and Li2CO3 as inexpensive base. The regioselectivities are similar to those observed with homogeneous palladium catalysts. Better yields were obtained with electron-deficient benzenesulfonyl chlorides than with the electron-rich ones. Notably, useful substituents such as bromo or iodo on the benzenesulfonyl chloride were tolerated, as no cleavage of the C–Br or C–I bonds was observed under these conditions. The use of Pd/C presents several advantages compared to the previously employed homogeneous palladium catalysts, as it can be easily removed by filtration at the end of the reaction. The major side-products of the reaction are HBr associated to Li2CO3. Therefore, this new protocol affords a very attractive synthetic scheme in terms of cost, simplicity and low environmental impact for the access to arylated heteroaromatics.
- Mao, Shuxin,Shi, Xinzhe,Soulé, Jean-Fran?ois,Doucet, Henri
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- Synthesis of [1]benzothiopheno[2,3-b][1]benzothiophene derivatives through iodine-mediated sulfuration reaction of 1,1-diarylethylenes
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Acceleration of the reaction for the synthesis of [1]benzothiopheno[2,3-b][1]benzothiophenes (BTBTs) from 1,1-diarylethylenes was accomplished by the addition of molecular iodine. Postulated intermediates 3-arylbenzo[b]thiophenes were also selectively prepared by simply changing the amount of iodine and the reaction time.
- Sakai, Shuta,Sato, Kazuki,Yoshida, Kazuhiro
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supporting information
(2019/12/27)
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- Para-coupling of phenols with C2/C3-substituted benzothiophene S-oxides
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C2 and C3 substituted benzothiophenes are common structures in medicinal and materials chemistry. The cross-coupling of phenols with benzothiophenes is a useful route towards these important molecules. In this report we reveal an efficient C–H/C–H-type cross-coupling of benzothiophenes, activated as their S-oxides, with phenols to give C2/C3 arylated benzothiophenes. Whereas previous reports describe cross-coupling at the ortho-position between phenols and sulfoxides, this procedure allows para-functionalization of phenols that typically have their ortho positions blocked.
- He, Zhen,Biremond, Tony,Perry, Gregory J.P.,Procter, David J.
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supporting information
(2020/06/17)
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- LIGAND COMPOUND, TRANSITION METAL COMPOUND, AND CATALYSTIC COMPOSITION COMPRISING THE SAME
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The present invention relates to a novel ligand compound, a transition metal compound, and a catalyst composition including the same, which can be advantageously used as a catalyst for a polymerization reaction in the production of an olefin-based polymer having a low density. The olefin polymer polymerized by using the catalyst composition including the transition metal compound can be used to produce a high molecular weight product having a low melt index (MI).COPYRIGHT KIPO 2021
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Paragraph 0159-0163
(2020/12/01)
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- Characterization of heterogeneous aryl-Pd(ii)-oxo clusters as active species for C-H arylation
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C-H arylation with heterogeneous palladium was investigated. The surface oxidation of Pd nanoparticles with a hypervalent iodine reagent, [Ph2I]BF4, resulted in the generation of Pd(ii)-aryl-oxo clusters, which were characterized as the crucial intermediate.
- Shin, Taeil,Kim, Minjun,Jung, Younjae,Cho, Sung June,Kim, Hyunwoo,Song, Hyunjoon
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supporting information
p. 14404 - 14407
(2020/12/01)
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- Visible-Light-Enhanced Suzuki–Miyaura Reactions of Aryl Chlorides in Water with Pd NPs Supported on a Conjugated Nanoporous Polycarbazole
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The visible-light-enhanced catalytic activation of aryl chlorides for Suzuki–Miyaura cross-coupling (SMC) reactions is highly challenging because of the strength of the C?Cl bond. In this work, palladium nanoparticles (Pd NPs) were grown on a conjugated nanoporous polycarbazole (CNP), named Pd/CNP. The hybrid material Pd/CNP could catalyze the SMC reactions of aryl chlorides with arylboronic acids in water under blue LED irradiation at room temperature with high efficiency. This protocol exhibited good functional group tolerance and the catalyst could be recycled without significant loss of its catalytic activity. CNP not only provided photogenerated electrons to enrich the electron density of the Pd NPs but also generated holes for the activation of the arylboronic acids.
- Guo, Bin,Li, Hong-Xi,Zha, Cheng-Hao,Young, David James,Li, Hai-Yan,Lang, Jian-Ping
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p. 1421 - 1427
(2019/02/26)
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- Base-Mediated Defluorosilylation of C(sp2)?F and C(sp3)?F Bonds
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The ability to selectively forge C–heteroatom bonds by C?F scission is typically accomplished by metal catalysts, specialized ligands and/or harsh reaction conditions. Described herein is a base-mediated defluorosilylation of unactivated C(sp2)?F and C(sp3)?F bonds that obviates the need for metal catalysts. This protocol is characterized by its simplicity, mild reaction conditions, and wide scope, even within the context of late-stage functionalization, constituting a complementary approach to existing C?Si bond-forming protocols.
- Liu, Xiang-Wei,Zarate, Cayetana,Martin, Ruben
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supporting information
p. 2064 - 2068
(2019/01/25)
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- Synthesis of C2 Substituted Benzothiophenes via an Interrupted Pummerer/[3,3]-Sigmatropic/1,2-Migration Cascade of Benzothiophene S-Oxides
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Functionalized benzothiophenes are important scaffolds found in molecules with wide ranging biological activity and in organic materials. We describe an efficient, metal-free synthesis of C2 arylated, allylated, and propargylated benzothiophenes. The reaction utilizes synthetically unexplored yet readily accessible benzothiophene S-oxides and phenols, allyl-, or propargyl silanes in a unique cascade sequence. An interrupted Pummerer reaction between benzothiophene S-oxides and the coupling partners yields sulfonium salts that lack aromaticity and therefore allow facile [3,3]-sigmatropic rearrangement. The subsequently generated benzothiophenium salts undergo a previously unexplored 1,2-migration to access C2 functionalized benzothiophenes.
- He, Zhen,Shrives, Harry J.,Fernández-Salas, José A.,Abengózar, Alberto,Neufeld, Jessica,Yang, Kevin,Pulis, Alexander P.,Procter, David J.
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supporting information
p. 5759 - 5764
(2018/04/10)
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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
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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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- Annulative π-Extension (APEX) of Heteroarenes with Dibenzosiloles and Dibenzogermoles by Palladium/o-Chloranil Catalysis
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Annulative π-extension (APEX) reactions of heteroarenes are described herein. A catalytic system comprising a cationic palladium species and o-chloranil using dimethyldibenzosiloles as π-extending agents enabled the extension of the π-system of benzo[b]thiophenes. π-Extended dibenzofurans and carbazoles could also be obtained from benzofuran and N-tosylindole, respectively, with dimethyldibenzogermole as a germanium-based π-extending agent. Mechanistic investigations indicated two possible reaction pathways involving carbopalladation-based double C-H arylation of benzothiophene or formal cycloaddition/oxidation cascades.
- Ozaki, Kyohei,Matsuoka, Wataru,Ito, Hideto,Itami, Kenichiro
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supporting information
p. 1930 - 1933
(2017/04/13)
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- Iridium-Catalyzed Asymmetric Hydrogenation of Benzo[b]thiophene 1,1-Dioxides
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An efficient iridium-catalyzed asymmetric hydrogenation of substituted benzothiophene 1,1-dioxides is described. The use of iridium complexes with chiral pyridyl phosphinite ligands provides access to highly enantiomerically enriched sulfones with substituents at the 2- and 3-position. Sulfones of this type are of interest as core structures of agrochemicals and pharmaceuticals. Moreover, they can be further reduced to chiral 2,3-dihydrobenzothiophenes.
- Tosatti, Paolo,Pfaltz, Andreas
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supporting information
p. 4579 - 4582
(2017/04/11)
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- Catalyst-Free Insertion of Sulfoxonium Ylides into Aryl Thiols. A Direct Preparation of β-Keto Thioethers
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Insertion of sulfoxonium ylides into the S-H bond of aryl thiols without the need for a catalyst is demonstrated, furnishing β-keto thioethers in excellent yield in most cases. The method overcomes traditional syntheses that employ metal catalysts in combination with diazo compounds or toxic and hard-prepared haloketones. The experimental setup consists of mixing the reagents in acetonitrile at room temperature. Additional experimental as well as kinetic isotopic effect studies give some insight into the mechanism of this reaction.
- Dias, Rafael M. P.,Burtoloso, Antonio C. B.
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supporting information
p. 3034 - 3037
(2016/07/06)
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- Palladium-Catalyzed Synthesis of 2,3-Disubstituted Benzothiophenes via the Annulation of Aryl Sulfides with Alkynes
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A new method has been developed for the synthesis of 2,3-disubstituted benzothiophenes involving the palladium-catalyzed annulation of aryl sulfides with alkynes. This convergent approach exhibited good functional group tolerance, providing rapid access to a diverse array of derivatives from simple, readily available starting materials. This protocol can also be used to synthesize 2-silyl-substituted benzothiophenes, which can be used as versatile platforms for the synthesis of 2,3-unsymmetrically substituted benzothiophenes.
- Masuya, Yoshihiro,Tobisu, Mamoru,Chatani, Naoto
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p. 4312 - 4315
(2016/11/03)
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- Synthesis of cyclopenta-fused polycyclic aromatic hydrocarbons utilizing aryl-substituted anilines
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Cyclopenta-fused polycyclic aromatic hydrocarbons (CP-PAHs), potentially electronically and biologically highly active materials, were synthesized from readily available 2-aryl-substituted anilines. Reactions occur under extremely mild, room temperature conditions using tBuONO as the sole reagent. The use of a nitrite source generates a reactive diazonium intermediate in situ that then reacts with a tethered polycyclic aromatic moiety by intramolecular aromatic substitution. This protocol could be presented as one of the simplest methods to access CP-PAHs.
- Choi, Yeojin,Chatterjee, Tanmay,Kim, Jun,Kim, Jun Soo,Cho, Eun Jin
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p. 6804 - 6810
(2016/07/23)
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- Impregnated palladium on magnetite as catalyst for direct arylation of heterocycles
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Palladium impregnated on magnetite is an efficient, cheap and easy to prepare catalyst for the direct arylation of heterocycles. Good yields are afforded under relatively mild conditions and a broad substrate scope is evident. The catalyst is regioselective in many cases, affording arylated products, at the C2- or C3-position (depending of the heterocycle used). The methodology can be extended to prepare chromenes through an intramolecular direct arylation reaction. Some evidence is provided for two catalyst deactivation pathways, which prevents efficient recycling.
- Cano, Rafael,Pérez, Juana M.,Ramón, Diego J.,McGlacken, Gerard P.
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p. 1043 - 1050
(2016/07/06)
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- Visible-light-induced regioselective synthesis of polyheteroaromatic compounds
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A method for visible-light-induced synthesis of polyheteroaromatics from 2-heteroaryl-substituted anilines and heteroarylalkynes was developed. The process, which uses fac-Ir(ppy)3 as the photocatalyst and tBuONO as the diazotization reagent, is highly regioselective.
- Chatterjee, Tanmay,Choi, Myung Gil,Kim, Jun,Chang, Suk-Kyu,Cho, Eun Jin
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p. 4203 - 4206
(2016/03/19)
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- Nickel-Catalyzed Cross-Coupling of Organolithium Reagents with (Hetero)Aryl Electrophiles
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Nickel-catalyzed selective cross-coupling of aromatic electrophiles (bromides, chlorides, fluorides and methyl ethers) with organolithium reagents is presented. The use of a commercially available nickel N-heterocyclic carbene (NHC) complex allows the reaction with a variety of (hetero)aryllithium compounds, including those prepared via metal-halogen exchange or direct metallation, whereas a commercially available electron-rich nickel-bisphosphine complex smoothly converts alkyllithium species into the corresponding coupled product. These reactions proceed rapidly (1 h) under mild conditions (room temperature) while avoiding the undesired formation of reduced or homocoupled products. Nickel-catalyzed cross-coupling of aromatic electrophiles with organolithium reagents is presented. The use of a commercially available nickel N-heterocyclic carbene complex allows reaction with a variety of (hetero)aryllithium compounds, whereas a commercially available electron-rich nickel bisphosphine complex smoothly converts alkyllithium species into the corresponding coupled product.
- Heijnen, Dorus,Gualtierotti, Jean-Baptiste,Hornillos, Valentín,Feringa, Ben L.
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supporting information
p. 3991 - 3995
(2016/03/16)
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- Room-Temperature Direct β-Arylation of Thiophenes and Benzo[b]thiophenes and Kinetic Evidence for a Heck-type Pathway
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The first example of a regioselective β-arylation of benzo[b]thiophenes and thiophenes at room temperature with aryl iodides as coupling partners is reported. This methodology stands out for its operational simplicity: no prefunctionalization of either st
- Colletto, Chiara,Islam, Saidul,Juliá-Hernández, Francisco,Larrosa, Igor
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supporting information
p. 1677 - 1683
(2016/02/20)
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- Palladium-catalyzed phosphine-free direct C-H arylation of benzothiophenes and benzofurans involving MIDA boronates
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With high regioselectivity, a series of benzoheterocyclic compounds were synthesized via palladiium-catalyzed phosphine-free C-H arylation of benzothiophenes/benzofurans with aryl MIDA boronates at 30-50 °C in moderate to excellent yields. MIDA boronates were used in C-H arylation of heterocycles for the first time. Under the optimal conditions, the benzothiophenes could be transformed into the β-arylbenzothiophenes, and the benzofurans gave only α-aryl-substituted products.
- Wang, Zhiwei,Li, Yabo,Yan, Beiqi,Huang, Mengmeng,Wu, Yangjie
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supporting information
p. 531 - 536
(2015/03/04)
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- In-Depth Assessment of the Palladium-Catalyzed Fluorination of Five-Membered Heteroaryl Bromides
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A thorough investigation of the challenging Pd-catalyzed fluorination of five-membered heteroaryl bromides is presented. Crystallographic studies and density functional theory (DFT) calculations suggest that the challenging step of this transformation is
- Milner, Phillip J.,Yang, Yang,Buchwald, Stephen L.
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supporting information
p. 4775 - 4780
(2015/10/28)
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- Aerobic and Efficient Direct Arylation of Five-Membered Heteroarenes and Their Benzocondensed Derivatives with Aryl Bromides by Bulky α-Hydroxyimine Palladium Complexes
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In the present work, a series of α-hydroxyimine palladium complexes with bulky substituents (i.e., {[Ar-N=C(R)-C(R)2-OH]PdCl2} (C1, R = Me, Ar = 2-diphenylmethyl-4,6-dimethylphenyl; C2, R = Me, Ar = 2,6-bis(diphenylmethyl)-4-methylphenyl; C3, R = Me, Ar = 2,6-bis(diphenylmethyl)-4-methyoxylphenyl; C4, R = Me, Ar = 2,6-bis(diphenylmethyl)-4-chlorophenyl; C5, R = Ph, Ar = 2,6-dimethylphenyl; C6, R = Ph, Ar = 2,6-diisopropylphenyl)) were synthesized and characterized. The structures of palladium complexes C1 and C2 were determined by X-ray diffraction. These bidentate N,O-palladium complexes were applied for direct arylation under aerobic conditions. The effects of the reaction conditions and ligand substitution on the catalytic activity were evaluated. Upon a low palladium loading of 0.5 mol %, the bulky palladium complex C6 was successfully used to catalyze the cross-coupling of a variety of five-membered heteroarenes and their benzo-condensed derivatives with (hetero)aryl bromides. The mechanistic investigation on the direct arylation supported the involvement of a Pd(0)/Pd(II) CMD process.
- Luo, Bao-Tian,Liu, Huan,Lin, Zhi-Jie,Jiang, Jingxing,Shen, Dong-Sheng,Liu, Rui-Zhi,Ke, Zhuofeng,Liu, Feng-Shou
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supporting information
p. 4881 - 4894
(2015/11/09)
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- General suzuki coupling of heteroaryl bromides by using tri-tert-butylphosphine as a supporting ligand
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A general procedure for the fast Suzuki coupling of major families of heteroaryl bromides was realized by using Pd(OAc)2/PtBu3 as the catalyst. Many couplings were finished within minutes at room temperature in n-butanol. Different from previous studies, three typical heteroaryl bromides were systematically examined in couplings of various heteroaryl and aryl boronic acids. A fast, general coupling of heteroaryl bromides is realized by using a single palladium catalyst supported by tri-tert-butylphosphine.
- Zou, Yinjun,Yue, Guizhou,Xu, Jianwei,Zhou, Jianrong
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supporting information
p. 5901 - 5905
(2015/03/30)
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- Reusable, highly active heterogeneous palladium catalyst by convenient self-encapsulation cross-linking polymerization for multiple carbon-carbon cross-coupling reactions at ppm to ppb palladium loadings
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Designing reusable high-performance heterogeneous palladium (Pd) catalysts via convenient, economic synthesis is of great importance to the industrial applications of various carbon-carbon crosscoupling reactions. We demonstrate herein a convenient one-pot self-encapsulation synthesis of a heterogeneous Pd catalyst [Pd@PDEB, PDEB = poly(1,3-diethynylbenzene)] directly from commercially available, economic precursors. In the synthesis, the formation of the cross-linked polymer networks and Pd encapsulation are accomplished simultaneously, turning a homogeneous Pd polymerization catalyst into the heterogeneous cross-coupling catalyst. As a unique, practical heterogeneous catalyst, Pd@PDEB shows remarkably high activity, high reusability, and high versatility towards at least four types of cross-coupling reactions (Suzuki-Miyaura, Stille, allylic arylation, and Mizoroki-Heck reactions) with even difficult reactants (aryl chlorides and heteroaryl halides) under aerobic conditions with Pd loadings down to ppm or even ppb levels. Evidences from hot filtration and 3-phase tests demonstrate the heterogeneous nature of the catalyst with very low Pd leaching and negligible contributions of leached homogeneous Pd species towards the coupling reactions.
- Donga, Zhongmin,Yea, Zhibin
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p. 3401 - 3414
(2015/02/05)
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- Pd/C as a catalyst for completely regioselective c=h functionalization of thiophenes under mild conditions
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The completely C3-selective arylation of thiophenes and benzo[b]thiophenes was achieved by using Pd/C as a heterogeneous catalyst without ligands or additives under mild reaction conditions. The practicability of this transformation is demonstrated by notable functional group tolerance and the insensitivity of the reaction to H2O and air. This method is also applicable to nitrogen- and oxygen-containing heterocycles, yielding the corresponding C2-arylated products. Three-phase tests along with Hg-poisoning and hot-filtration tests suggest that the catalytically active species is heterogeneous in nature. I+ can do better! Pd/C can be used without ligands or additives to catalyze the completely C3-selective arylation of diversely substituted thiophenes and benzo[b]thiophenes under mild reaction conditions. The physical nature of the catalytic species was investigated and the mechanism was studied. Relative rate data generated in a "robustness screen" were used to design a complex substrate that undergoes highly chemoselective sequential functionalization. Copyright
- Tang, Dan-Tam D.,Collins, Karl D.,Ernst, Johannes B.,Glorius, Frank
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supporting information
p. 1809 - 1813
(2014/03/21)
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- Benzenesulfonyl chlorides: New reagents for access to alternative regioisomers in palladium-catalysed direct arylations of thiophenes
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The palladium-catalysed coupling of benzenesulfonyl chlorides with thiophene derivatives allows regioselective access to β-arylated thiophenes. The reaction proceeds with easily accessible catalyst, base and substrates, without oxidant or ligand and tolerates a variety of substituents on both the benzene and thiophene moieties.
- Yuan, Kedong,Doucet, Henri
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p. 392 - 396
(2014/01/06)
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- Completely regioselective direct C-H functionalization of benzo[b]thiophenes using a simple heterogeneous catalyst
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The first completely selective C3 C-H arylation of benzo[b]thiophenes is reported, demonstrating previously unexploited reactivity of palladium. Benzo[b]thiophenes are coupled with readily available aryl chlorides using a ligand-free, dual catalytic system of heterogeneous Pd/C and CuCl. The reaction is operationally simple and insensitive to air and moisture, and it provides valuable products with complete selectivity. Significant investigations into the nature of the active catalytic species and mechanistic considerations are discussed.
- Tang, Dan-Tam D.,Collins, Karl D.,Glorius, Frank
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supporting information
p. 7450 - 7453
(2013/06/27)
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- Room-temperature photoinduced direct C-H-arylation via base-promoted homolytic aromatic substitution
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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.
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supporting information
p. 1174 - 1177
(2013/04/24)
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- Pd-catalyzed β-selective direct C-H bond arylation of thiophenes with aryltrimethylsilanes
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Direct arylation of thiophenes and benzothiophenes with aryltrimethylsilanes was effectively catalyzed by PdCl2(MeCN) 2 in the presence of CuCl2 as an oxidant. The reaction preferentially occurred at the β-position of both
- Funaki, Kenji,Sato, Tetsuo,Oi, Shuichi
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supporting information
p. 6186 - 6189
(2013/02/23)
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- INHIBITORS OF VIRAL REPLICATION, THEIR PROCESS OF PREPARATION AND THEIR THERAPEUTICAL USES
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The present invention relates to compounds of formula (1) as claimed in claim 1, their use in the treatment or the prevention of viral disorders, including HIV. (Formula I)
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Page/Page column 50
(2012/10/18)
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- Inhibitors of viral replication, their process of preparation and their therapeutical uses
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The present invention relates to compounds, their use in the treatment or the prevention of viral disorders, including HIV.
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Paragraph 0092; 0093
(2013/03/26)
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- Oxidative biaryl coupling of thiophenes and thiazoles with arylboronic acids through palladium catalysis: Otherwise difficult C4-selective C-H arylation enabled by boronic acids
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(Chemical Equation Presented) It adds up to 4! Thiophenes and thiazoles can be arylated in the 4- rather than the expected 5-position in a new C-H functionalization reaction (see scheme; TEMPO: 2,2,6,6-tetramethylpiperidine-N- oxyl). The boronic acid proved to be the key to achieving the otherwise difficult C4 selectivity. The method was applied to a concise synthesis of a key pharmacological structure with potential for treatment of Alzheimers disease.
- Kirchberg, Sylvia,Tani, Satoshi,Ueda, Kirika,Yamaguchi, Junichiro,Studer, Armido,Itami, Kenichiro
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supporting information; experimental part
p. 2387 - 2391
(2011/04/21)
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- Ionic liquid supported organotin reagents: Green tools for stille cross-coupling reactions with brominated substrates
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Efficiency of ionic liquid supported organotin reagents in Stille cross-coupling reactions involving aryl bromides has been investigated. In a general manner, products were isolated with good yields by using a very simple catalytic system without the need of solvent, ligand, or additives. The organotin compounds were recycled without loss of activity and the contamination by tin was limited and controlled ([Sn] 3 ppm). Clean tin's good! Efficiency of ionic liquid supported organotin reagents in Stille cross-coupling reactions involving aryl bromides has been investigated. Products were isolated with good yields by using a verysimple catalytic system. Organotin compounds were recycled without loss of activity and the contamination by tin was limited ([Sn] 3 ppm).
- Louaisil, Nicolas,Pham, Phuoc Dien,Boeda, Fabien,Faye, Djibril,Castanet, Anne-Sophie,Legoupy, Stephanie
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supporting information; experimental part
p. 143 - 149
(2011/03/18)
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- Synthesis of 3-substituted benzo[b]thiophenes via the reaction of α-substituted 2-lithio-β-methoxystyrenes with sulfur
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3-Substitued benzo[b]thiophenes were synthesized in reasonable overall yields from α-substituted 2-bromo-β-methoxystyrenes. Thus, the bromine-lithium exchange between these bromostyrenes with butyllithium in diethyl ether at 0 °C followed by reaction with sulfur afforded the corresponding a-substituted β-methoxy-2-sulfanylstyrenes. These were then treated with an equimolar amount of concentrated hydriodic acid in acetonitrile at room temperature to give the desired products. The Japan Institute of Heterocyclic Chemistry.
- Kobayashi, Kazuhiro,Nakai, Daisuke,Fukamachi, Shuhei,Konishi, Hisatoshi
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experimental part
p. 1703 - 1709
(2011/04/15)
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- A general catalyst for the β-selective C - H bond arylation of thiophenes with iodoarenes
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Open access: The normally less-reactive β position of thiophenes was previously inaccessible to direct functionalization. However, the β selectivity observed with the catalytic system PdCl2/P{OCH(CF 3)2}3/Ag2CO3 in the arylation of thiophenes with iodoarenes (see scheme) is a remarkably general phenomenon applicable to unsubstituted, monosubstituted, and disubstituted thiophene derivatives, as well as thiophene-containing fused aromatic compounds.
- Ueda, Kirika,Yanagisawa, Shuichi,Yamaguchi, Junichiro,Itami, Kenichiro
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supporting information; experimental part
p. 8946 - 8949
(2011/02/21)
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- Synthesis of biaryls and oligoarenes using aryl[2-(hydroxymethyl)phenyl] dimethylsilanes
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Through intramolecular activation, highly stable aryl[2-(hydroxymethyl) phenyl]dimethylsilanes can selectively transfer their aryl groups to effect a cross-coupling reaction with various aryl bromides and chlorides in the presence of a weak non-fluoride base and a palladium/copper catalyst. This reaction tolerates a wide range of functional groups, producing the corresponding functionalized biaryls in high yields with excellent chemoselectivity. Newly disclosed reaction conditions allow the recovery of a cyclic silyl ether in modest-to-good yields and reuse for the synthesis of the arylsilanes. The introduction of two isopropyl groups on the silicon center instead of methyl groups improves the stability and allows quantitative recovery of the silicon residue. Finally, aryl halides having an O-protected [2- (hydroxymethyl)phenyl] dimethylsilyl group cross-couple with the arylsilane reagents to give silyl-functionalized biaryls. Upon deprotection, the biaryls further react with the silylated electrophiles. The iterative cross-couplingdeprotection sequences allow rapid assembly of silylated oligoarenes. Syntheses of di- and trisilyloligoarenes are also achieved by use of orthogonal O-protecting groups.
- Chen, Jinshui,Tanaka, Masaaki,Sahoo, Akhila K.,Takeda, Masahide,Yada, Akira,Nakao, Yoshiaki,Hiyama, Tamejiro
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experimental part
p. 554 - 569
(2010/07/02)
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- A new synthesis of benzo[b]thiophenes utilizing an interrupted Pummerer reaction
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A convenient synthesis of 3-arylbenzo[b]thiophenes utilizing an interrupted Pummerer reaction of 2-(1-arylvinyl)phenyl ethyl sulfoxides is described. Thus, treatment of these sulfoxides, which were readily prepared from 2-sulfanylphenyl ketones or 2-fluor
- Kobayashi, Kazuhiro,Horiuchi, Mai,Fukamachi, Shuhei,Konishi, Hisatoshi
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experimental part
p. 2430 - 2435
(2009/07/25)
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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 21; 24
(2009/04/24)
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- Convenient synthesis of 3-substituted benzo[b]thiophenes by iodine-mediated cyclization of α-substituted 2-(1-Phenylethylthio)styrenes
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A new and convenient method for the preparation of 3-substituted benzo[b]thiophenes was developed. α-Substituted 2-(1-phenylethylthio) styrenes, which could easily be prepared from 2-mercaptophenyl ketones or benzenethiols in two or three steps, respectively, underwent 5-endo cyclization on treatment with iodine in the presence of sodium hydrogencarbonate in acetonitrile at room temperature to give 3-substituted benzo[b]thiophenes in fair to good yields.
- Kobayashi, Kazuhiro,Nakamura, Daizo,Miyamoto, Kazuna,Morikawa, Osamu,Konishi, Hisatoshi
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experimental part
p. 1780 - 1784
(2009/07/25)
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- Aromatic ring-opening of 2-fluorobenzothiophenes by alkyllithiums
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Diphenylacetylenes are obtained when alkyllithium reagents are added to 3-aryl-2-fluorobenzothiophenes at low temperature. The aromatic ring-opening mechanism involves a nucleophilic addition of the alkyllithium to the sulfur atom of the thiophene. The re
- Belley, Michel,Douida, Zohra,Mancuso, John,De Vleeschauwer, Marc
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p. 247 - 250
(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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- Efficient method for the synthesis of hetarenoindanones based on 3-arylhetarenes and their conversion into hetarenoindenes
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A series of hetarenoindanones have been prepared by direct double metalation of the appropriate 3-phenylhetarene with butyllithium in the presence of TMEDA followed by treatment of the resulting dilithium compound with ethyl N ,N-dimethylcarbamate. All hetarenoindanones were reduced according to Wolff-Kishner by hydrazine in the presence of KOH to the corresponding hetarenoindenes.
- Kashulin, Igor A.,Nifant'ev, Ilya E.
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p. 5476 - 5479
(2007/10/03)
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