- Suzuki-Miyaura reactions of arenediazonium salts catalyzed by Pd(0)/C. One-pot chemoselective double cross-coupling reactions
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The Suzuki-Miyaura cross-coupling of arenediazonium tetrafluoroborate salts with boronic acid partners catalyzed by Pd(0)/C is described as a practical and efficient alternative to classical homogeneous conditions. Reactions conducted in alcoholic solvents proved to be extremely fast using mild conditions. Additionnaly, we developed a chemoselective double Suzuki-Miyaura cross-coupling in a single reaction vessel allowing the synthesis of unsymmetrical terphenyls.
- Taylor, Rachel H.,Felpin, Francois-Xavier
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- (DPEPhos)Ni(mesityl)Br: An Air-Stable Pre-Catalyst for Challenging Suzuki-Miyaura Cross-Couplings Leading to Unsymmetrical Biheteroaryls
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The successful application of (DPEPhos)Ni(mesityl)Br (C1) as a pre-catalyst in the Suzuki-Miyaura cross-coupling of heteroaryl chlorides or bromides and heteroaryl boronic acids is reported. The use of C1 in this context allows for such reactions to be conducted under mild conditions (2 mol% Ni, 25 °C), including cross-couplings leading to unsymmetrical biheteroaryls. Successful transformations of this type involving problematic pyridinyl boronic acid substrates (10 mol% Ni, 60 °C) are also described.
- Sawatzky, Ryan S.,Stradiotto, Mark
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Read Online
- New Nickel-Based Catalytic System with Pincer Pyrrole-Functionalized N-Heterocyclic Carbene as Ligand for Suzuki-Miyaura Cross-Coupling Reactions
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A new catalytic system with Ni(NO3)2·6H2O as the catalyst and a pincer pyrrole-functionalized N-heterocyclic carbene as the ligand was employed in the Suzuki-Miyaura cross-coupling reactions of aryl iodides with arylboronic acids. With 5 mol% catalyst, the catalytic reactions proceeded at 160 °C, giving coupling products in isolated yields of up to 94% in short reaction times (1-4 h). The system worked efficiently with aryl iodides bearing electron-donating or electron-withdrawing groups and arylboronic acids with electron-donating groups. Steric effects were observed for both aryl iodides and arylboronic acids. It is proposed that the reactions underwent a Ni(I)/Ni(III) catalytic cycle.
- Guo, Zhifo,Lei, Xiangyang
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supporting information
(2021/09/11)
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- Highly Efficient Synthesis of 2-Substituted Benzo[ b ]furan Derivatives from the Cross-Coupling Reactions of 2-Halobenzo[ b ]furans with Organoalane Reagents
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A highly efficient and simple route for the synthesis of 2-substituted benzo[ b ]furans has been developed by palladium-catalyzed cross-coupling reaction of 2-halobenzo[ b ]furans with aryl, alkynyl, and alkylaluminum reagents. Various 2-aryl-, 2-alkynyl-, and 2-alkyl-substituted benzo[ b ]furan derivatives can be obtained in 23-97% isolated yields using 2-3 mol% PdCl 2/4-6 mol% XantPhos as the catalyst under mild reaction conditions. The aryls bearing electron-donating or electron-withdrawing groups in 2-halobenzo[ b ]furans gave products in 40-97% isolated yields. In addition, aluminum reagents containing thienyl, furanyl, trimethylsilanyl, and benzyl groups worked efficiently with 2-halobenzo[ b ]furans as well, and three bioactive molecules with 2-substituted benzo[ b ]furan skeleton were synthesized. Furthermore, the broad substrates scope and the typical maintenance of vigorous efficiency on gram scale make this protocol a potentially practical method to synthesize 2-substituted benzo[ b ]furan derivatives. On the basis of the experimental results, a possible catalytic cycle has been proposed.
- Wen, Chang,Wu, Chuan,Luo, Ruiqiang,Li, Qinghan,Chen, Feng
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supporting information
p. 3847 - 3861
(2021/07/02)
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- Acid-promoted selective synthesis of trifluoromethylselenolated benzofurans with Se-(trifluoromethyl) 4-methylbenzenesulfonoselenoate
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A Br?nsted acid-promoted trifluoromethylselenolation of benzofurans was disclosed by using Se-(trifluoromethyl) 4-methylbenzenesulfonoselenoate as a stable and easily prepared electrophilic trifluoromethylselenolating reagent. A wide range of SeCF3-substituted benzofuran derivatives were obtained in moderate to good yields with excellent regioselectivity. The tandem cyclization/trifluoromethylselenolation procedure of 1-methoxy-2-(arylethynyl)benzenes were also realized by engaging FeCl3 as the catalyst.
- Liu, Juyan,Tian, Miaomiao,Li, Ankun,Ji, Liangshuo,Qiu, Di,Zhao, Xia
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supporting information
(2021/02/01)
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- Regioselective Direct C2 Arylation of Indole, Benzothiophene and Benzofuran: Utilization of Reusable Pd NPs and NHC-Pd@MNPs Catalyst for C–H Activation Reaction
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Abstract: A regioselective C2 arylation of indoles, benzothiophene and benzofuran without directing group has been accomplished using economically cheap Pd NPs and NHC-Pd@MNPs catalyst. The reusable catalyst is efficiently employed to access C2 arylated heterocycles in good to excellent yield. The reusability of the catalyst is studied up to five cycles and a gram-scale synthesis has been achieved. The reaction mechanism is well supported by control experiments and literature precedents. Grapic Abstract: [Figure not available: see fulltext.]
- Hegde, Rajeev V.,Ong, Tiow-Gan,Ambre, Ram,Jadhav, Arvind H.,Patil, Siddappa A.,Dateer, Ramesh B.
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p. 1397 - 1405
(2020/10/02)
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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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- Method for synthesizing 2-aryl benzofuran and derivatives thereof
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The invention relates to a method for synthesizing 2-aryl benzofuran and derivatives thereof. According to the method, cheap and easily available 2, 3-dihydrobenzofuran compounds, an organic boron reagent and bromo-aromatic hydrocarbon are taken as raw materials, and a two-step cascade reaction is carried out under mild conditions, so that the 2-aryl benzofuran product can be conveniently prepared. At present, the reported synthesis methods of 2-aryl benzofuran and derivatives thereof mainly have the problems of long synthesis route, expensive raw materials, harsh reaction conditions and the like. Compared with reported methods, the synthesis method has the advantages of specific reaction selectivity, short reaction route and the like, and a convenient and efficient synthesis strategy is provided for laboratory preparation or industrial production of 2-arylbenzofuran products.
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Paragraph 0037-0040
(2020/05/08)
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- σ-Bond initiated generation of aryl radicals from aryl diazonium salts
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σ-Bond nucleophiles and molecular oxygen transform aryl diazonium salts into aryl radicals. Experimental and computational studies show that Hantzsch esters transfer hydride to aryl diazonium species, and that oxygen initiates radical fragmentation of the diazene intermediate to produce aryl radicals. The operational simplicity of this addition-fragmentation process for the generation of aryl radicals, by a polar-radical crossover mechanism, has been illustrated in a variety of bond-forming reactions.
- Chan, Bun,McErlean, Christopher S. P.,Nashar, Philippe E.,Tatunashvili, Elene
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supporting information
p. 1812 - 1819
(2020/03/17)
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- Transition-Metal-Free Synthesis of Heterobiaryls through 1,2-Migration of Boronate Complex
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The synthesis of a diverse range of heterobiaryls has been achieved by a transition-metal-free sp2–sp2 cross-coupling strategy using lithiated heterocycle, aryl or heteroaryl boronic ester and an electrophilic halogen source. The construction of heterobiaryls was carried out through electrophilic activation of the aryl–heteroaryl boronate complex, which triggered 1,2-migration from boron to the carbon atom. Subsequent oxidation of the intermediate boronic ester afforded heterobiaryls in good yield. A comprehensive 11B NMR study has been conducted to support the mechanism. The cross coupling between two nucleophilic cross coupling partners without transition metals reveals a reliable manifold to procure heterobiaryls in good yields. Various heterocycles like furan, thiophene, benzofuran, benzothiophene, and indole are well tolerated. Finally, we have successfully demonstrated the gram scale synthesis of the intermediates for an anticancer drug and OLED material using our methodology.
- Paul, Swagata,Das, Kanak Kanti,Manna, Samir,Panda, Santanu
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supporting information
p. 1922 - 1927
(2020/02/04)
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- Looking for new xanthine oxidase inhibitors: 3-Phenylcoumarins versus 2-phenylbenzofurans
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Overproduction of uric acid in the body leads to hyperuricemia, which is also closely related to gout. Uric acid production can be lowered by xanthine oxidase (XO) inhibitors. Inhibition of XO has also been proposed as a mechanism for improving cardiovascular health. Therefore, the search for new efficient XO inhibitors is an interesting topic in drug discovery. 3-Phenylcoumarins and 2-phenylbenzofurans are privileged scaffolds in medicinal chemistry. Their structural similarity makes them interesting molecules for a comparative study. Methoxy and nitro substituents were introduced in both scaffolds. The current study gives some insights into the synthesis and biological activity of these molecules against this important target. For the best compound of the series, the 3-(4-methoxyphenyl)-6-nitrocoumarin (4), the IC50 value, type of inhibition, cytotoxicity on B16F10 cells and ADME theoretical properties, were determined. Docking studies were also performed in order to better understand the interactions of this molecule with the XO binding pocket. This work is a preliminary screening for further design and synthesis of new non-purinergic derivatives as potential compounds involved in the inflammatory suppression, specially related to gout.
- Borges, Fernanda,Delogu, Giovanna L.,Era, Benedetta,Fais, Antonella,Gatto, Gianluca,Kumar, Amit,Matos, Maria J.,Pintus, Francesca,Uriarte, Eugenio
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p. 774 - 780
(2020/07/07)
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- Preparation method of benzofuran derivative
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The invention belongs to the field of organic chemical synthesis, and particularly relates to a preparation method of a benzofuran derivative. According to the specific technical scheme, the preparation method of the benzofuran derivative comprises the fo
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Paragraph 0066-0070
(2020/11/12)
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- Magnetic nanoparticles-supported palladium catalyzed Suzuki-Miyaura cross coupling
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A new magnetic nanoparticles-supported palladium(II) nanomagnetic catalyst (Pd-AcAc-Am-Fe3O4?SiO2) was synthesized and characterized using attenuated total reflectance infrared spectroscopy (ATR-IR), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), energy-dispersive X-ray spectroscopy (EDS), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The nanomagnetic catalyst was used as an efficient catalyst for the Suzuki-Miyaura cross-coupling of various aryl bromides/chlorides/iodides with phenylboronic acid. The effect of varying solvents, base, temperature, reaction time and catalyst amount on the performance of the Suzuki-Miyaura cross-coupling is investigated. The notable advantages of heterogeneous nanomagnetic catalyst are excellent yields, mild reaction conditions, short reaction time, easy magnetic work-up and recyclability. Moreover, the new nanomagnetic catalyst could be easily recovered with an external magnet and reused at least six times without significant loss of its catalytic activity.
- Vibhute, Sandip P.,Mhaldar, Pradeep M.,Shejwal, Rajendra V.,Pore, Dattaprasad M.
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supporting information
(2020/01/21)
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- Highly effective cellulose supported 2-aminopyridine palladium complex (Pd(II)-AMP-Cell?Al2O3) for Suzuki-Miyaura and Mizoroki–Heck cross-coupling
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In the present work, a novel, highly efficient, retrievable organo–inorganic hybrid heterogeneous catalyst (Pd(II)-AMP-Cell?Al2O3) has been prepared by covalent grafting of 2-aminopyridine on chloropropyl modified cellulose-alumina composite followed by complexation with palladium acetate. The catalyst was characterized by techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), inductive coupled plasma-atomic emission spectroscopy (ICP-AES) and thermo gravimetric analysis (TGA). The catalyst has been successfully employed in Suzuki-Miyaura as well as Mizoroki–Heck cross-coupling reactions. The reactions proceed smoothly resulting in the high yields of cross-coupling products (81 to 95%) within short reaction times. The catalyst can be efficiently recovered by simple filtration and reused for multiple cycles without considerable loss in the catalytic activity. The key-features of the present protocol include mild reaction conditions, simple work-up procedure, high stability of the catalyst, high turnover number (TON) and frequency (TOF), ease recovery and reusability of the catalyst.
- Mhaldar, Pradeep,Pore, Dattaprasad,Rashinkar, Gajanan,Vibhute, Sandip
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- One-pot Tandem Heck alkynylation/cyclization reactions catalyzed by Bis(Pyrrolyl)pyridine based palladium pincer complexes
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Ligand assisted palladium catalyzed one-pot tandem Heck alkynylation/cyclization reactions for the synthesis of benzofurans was reported in this paper. Well-defined palladium-pincer complexes exhibited excellent catalytic activities for the one-pot tandem Heck alkynylation/cyclization reactions yielding benzofuran derivatives using 0.1 molpercent catalyst. All the catalytic reactions are performed in air. The effects of variables such as solvents, the temperature on the catalytic activity are also reported. High product conversion was obtained for differently substituted 2-iodophenol at 120 °C in 10 h.
- Yadav, Seema,Dash, Chandrakanta
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- Palladium complexes with an annellated mesoionic carbene (MIC) ligand: Catalytic sequential Sonogashira coupling/cyclization reaction for one-pot synthesis of benzofuran, indole, isocoumarin and isoquinolone derivatives
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Two Pd(ii) complexes (1 and 2) featuring a fused π-conjugated imidazo[1,2-a][1,8]naphthyridine-based mesoionic carbene ligand have been synthesized and structurally characterized. Both complexes effectively catalyze the one-pot synthesis of benzofuran starting from phenylacetylene and 2-iodophenol under mild conditions. Complex 1 is found to be an excellent catalyst for the straightforward access to a library of benzofuran, indole, isocoumarin and isoquinolone derivatives by the reaction of terminal alkynes with 2-iodo derivates of phenol, N-methyl aniline, benzoic acid and N-methyl benzamide, respectively. The general utility of the catalytic method is demonstrated using a variety of diversely substituted terminal alkynes and the corresponding desired products are obtained in good to excellent yields. On the basis of control experiments, a two-cycle mechanism is proposed which involves the Sonogashira coupling of 2-iodo derivatives with alkynes and the subsequent cyclization of the corresponding 2-alkynyl compounds.
- Bera, Jitendra K.,Daw, Prosenjit,Reshi, Noor U Din,Tyagi, Akshi
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supporting information
p. 15238 - 15248
(2020/11/18)
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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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- Facile synthesis of 2-substituted benzo[: B] furans and indoles by copper-catalyzed intramolecular cyclization of 2-alkynyl phenols and tosylanilines
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A catalytic amount of CuCl and Cs2CO3 was employed to synthesize a variety of 2-substituted benzo[b]furans and indoles by an intramolecular cyclization of 2-alkynyl phenols and tosylanilines. This protocol features mild conditions, h
- Rong, Zhouting,Gao, Kexin,Zhou, Lei,Lin, Jianyuan,Qian, Guoying
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p. 17975 - 17978
(2019/06/24)
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- A palladium catalyzed aryl alkyne preparation method
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The invention discloses a palladium catalyzed aryl alkyne of the preparation method, comprises the following steps: in the catalyst, under the action of the ligand and alkali, substituted with aryl sulfonyl chloride alkynoic occurs in the organic solvent escapes suosuo the coupling reaction, after the reaction is finished after treatment to obtain the aryl alkyne. Used in the preparation method of the cheap raw material, the reaction and simple post treatment operation, at the same time, the reaction less side reaction, high yield of the product.
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Paragraph 0034; 0035; 0036
(2019/05/21)
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- Pd-catalyzed C–H bond activation of Indoles for Suzuki reaction
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Abstract: We present a practical method for Suzuki coupling by which unprotected or N-protected indoles may be selectively arylated in the C2-position through direct C–H bond activation by electrophilic Pd(TFA) 2 catalyst. The protocol is operationally simple as it is carried out in dioxane/water mixture, and air as the sole oxidant at room temperature. Various 2-arylated indoles were obtained in good yields. The protocol works for benzofuran, pyrrole and thiophene also. Graphic abstract: Selective C-2 arylation of heterocycles using Pd(II) catalyst via C–H activation was performed under ambient condition. C3–C2 migration of organopalladium intermediate controls the reaction pathway.[Figure not available: see fulltext.].
- Banerjee, Isita,Ghosh, Keshab Ch,Sinha, Surajit
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- Unexpected detection of 3-aroylbenzofuran side products in the preparation of 2-arylbenzofurans: Identification, characterization, and comparison with chalcone's fragmentation patterns using EI/MSn
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A gas chromatography-mass spectrometry study of the intramolecular Wittig reaction revealed, together with the expected 2-phenylbenzofuran, the formation of an unexpected side product that has not been reported until now. This study reports the identification of the by-product, ie, the 3-benzoyl-2-phenylbenzofuran, on the base of its mass spectrometric behaviour using a combination of electron ionization, exact mass measurement, multiple stage mass spectrometry, and labelled compounds. This study reports the common fragmentation pathways and discusses possible fragment structures of characteristic ions from a series of 3-aroyl-2-arylbenzofuran derivatives obtained as by-product under Wittig conditions. Emphasis is laid on the formation and structure investigation of the [M-H]+ and [M-OH]+ ions. Our results showed interesting analogies with the mass spectrometric behaviour of chalcones.
- Begala, Michela,Delogu, Giovanna Lucia
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p. 750 - 760
(2019/09/03)
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- Well-Defined N-Heterocyclic Carbene-Palladium Complexes as Efficient Catalysts for Domino Sonogashira Coupling/Cyclization Reaction and C-H bond Arylation of Benzothiazole
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Well-defined and air-stable PEPPSI (Pyridine Enhanced Precatalyst Preparation Stabilization and Initiation) themed palladium bis-N-heterocyclic carbene complexes have been developed for the domino Sonogashira coupling/cyclization reaction of 2-iodophenol with a variety of terminal alkynes and C-H bond arylation of benzothiazole with aryl iodides. The PEPPSI themed palladium complexes, 2a and 2b were synthesized in good yields from the reaction of corresponding imidazolium salts with PdCl2 and K2CO3 in pyridine. The new air-stable palladium-NHC complexes were characterized by NMR spectroscopy, X-ray crystallography, elemental analysis, and mass spectroscopy studies. The PEPPSI themed palladium(II) bis-N-heterocyclic carbene complexes 2a and 2b exhibited excellent catalytic activities for domino Sonogashira coupling/cyclization reaction of 2-iodophenol with terminal alkynes yielding benzofuran derivatives. In addition, the palladium complexes, 2a and 2b successfully catalyzed the direct C-H bond arylation of benzothiazole with aryl iodides as coupling partners in presence of CuI as co-catalyst.
- Yadav, Seema,Singh, Ajeet,Mishra, Isha,Ray, Sriparna,Mobin, Shaikh M.,Dash, Chandrakanta
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- Synthesis of benzofurans from terminal alkynes and iodophenols catalyzed by recyclable palladium nanoparticles supported on N,O-dual doped hierarchical porous carbon under copper- and ligand-free conditions
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We herein report that a stable and recyclable heterogeneous catalyst, consisting of Pd nanoparticles supported on N,O-dual doped hierarchical porous carbon derived from naturally available and renewable biomass-bamboo shoots, which allows for highly efficient one-pot tandem reaction of o-iodophenols with terminal alkynes to synthesize biologically active 2-benzofuran derivatives under copper- and ligand-free conditions. The catalyst performed superior catalytic performance compared with the analogous Pd/C and supported on other metal oxides under otherwise identical conditions. A broad set of aryl and alkyl terminal alkynes can be effectively coupled /cyclized with various o-iodophenols to afford their corresponding 2-benzofurans in good to high yields with good tolerance of multiple functional groups. Moreover, the catalyst showed good stability and could be reused several times without significant loss of activity.
- Ji, Guijie,Duan, Yanan,Zhang, Shaochun,Yang, Yong
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p. 101 - 108
(2018/05/05)
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- CuI catalyzed domino coupling–cyclization of 2-iodo-phenols and 1-alkynes to the synthesis of 2-substituted benzo[b]furans/furo-pyridines
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CuI/proline-catalyzed coupling reaction of 2-iodo-phenols with terminal alkynes and the following cyclization process is carried out successively in DMSO at 80 °C. Under this tandem process, 2-substituted benzo[b]furans/furo-pyridines were synthesized in good to excellent yields with a great diversity.
- Chen, Ze-Pin,Zhou, Yi,Shui, Meng-Zhu,Liu, Feng
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supporting information
p. 133 - 136
(2018/12/11)
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- Aerobic, Metal-Free, and Catalytic Dehydrogenative Coupling of Heterocycles: En Route to Hedgehog Signaling Pathway Inhibitors
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The nitrosonium ion-catalyzed dehydrogenative coupling of heteroarenes under mild reaction conditions is reported. The developed method utilizes ambient molecular oxygen as a terminal oxidant, and only water is produced as byproduct. Dehydrogenative coupl
- Bering, Luis,Paulussen, Felix M.,Antonchick, Andrey P.
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supporting information
p. 1978 - 1981
(2018/04/16)
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- Transition-metal-free base catalyzed intramolecular cyclization of 2-ynylphenols for efficient and facile synthesis of 2-substituted benzo[b]furans
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A transition-metal-free base catalyzed intramolecular cyclization of 2-ynylphenols was developed for the facile synthesis of 2-substituted benzo[b]furans. Various 2-aryl and 2-alkyl substituted benzo[b]furans can be obtained with good to excellent yields
- Liu, Yong,Lu, Tao,Tang, Wei-Fang,Gao, Jian
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p. 28637 - 28641
(2018/08/29)
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- Arylation synthesis method for novel five-membered aromatic heterocycle and aromatic-ring five-membered aromatic heterocycle
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The invention belongs to the technical field of organic synthesis and in particular relates to an arylation synthesis method for a five-membered aromatic heterocycle or an aromatic-ring five-memberedaromatic heterocycle under the participation of an arylhydrazine derivative serving as a novel arylation reagent. The method comprises the steps: adding a raw material and aroyl hydrazine into a reactor, and carrying out a reaction at 60-100 DEG C for 8-24h under the condition that an oxidant and a transition metal catalyst are added; after the reaction is ended, carrying out suction filtration, extracting a filtrate by using ethyl acetate, carrying out drying to obtain a crude product of a target compound, and carrying out column chromatography on silica gel to obtain a pure product of the target compound. The arylation synthesis method for the five-membered aromatic heterocycle or the aromatic-ring five-membered aromatic heterocycle is scientific and reasonable and has the advantages such as simplicity and convenience in operation, relatively high yield and simplicity in amplification and purification.
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Paragraph 0112-0115; 0140-0143
(2018/07/07)
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- Synthesis method and application of terephthalyl alcohol-derived bidentate phosphite ligand
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The invention discloses a synthesis method and an application of a terephthalyl alcohol-derived bidentate phosphite ligand. The ligand has the following structural formula defined in the specification, wherein R is H or t-Bu. The ligand is a white solid, and is stable in structure, simple in synthesis, high in yield and easy to prepare in large quantities; in a nitrogen atmosphere, the ligand anda palladium salt are subjected to reaction in an organic solvent to obtain a ligand/palladium catalyst, a Suzuki-Miyaura reaction is catalyzed, the reaction conversion rate is high and the substrate universality is high.
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Paragraph 0033; 0036; 0037; 0050
(2019/01/06)
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- Method for synthesizing benzofuranol derivative by nickel-catalysis of phenethynyl phenol under microwave irradiation
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The invention discloses a method for synthesizing a benzofuranol derivative by nickel-catalysis of phenethynyl phenol under microwave irradiation; a catalytic amount of catalyst nickel chloride, ligand 1,10-phenanthroline(1,10-Phen), auxiliary catalyst po
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Paragraph 0025; 0052
(2018/09/11)
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- Base-free nickel-catalysed decarbonylative Suzuki–Miyaura coupling of acid fluorides
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The Suzuki–Miyaura cross-coupling of organoboron nucleophiles with aryl halide electrophiles is one of the most widely used carbon–carbon bond-forming reactions in organic and medicinal chemistry1,2. A key challenge associated with these transformations is that they generally require the addition of an exogenous base, the role of which is to enable transmetallation between the organoboron nucleophile and the metal catalyst3. This requirement limits the substrate scope of the reaction because the added base promotes competitive decomposition of many organoboron substrates3–5. As such, considerable research has focused on strategies for mitigating base-mediated side reactions6–12. Previous efforts have primarily focused either on designing strategically masked organoboron reagents (to slow base-mediated decomposition)6–8 or on developing highly active palladium precatalysts (to accelerate cross-coupling relative to base-mediated decomposition pathways)10–12. An attractive alternative approach involves identifying combinations of catalyst and electrophile that enable Suzuki–Miyaura-type reactions to proceed without an exogenous base12–14. Here we use this approach to develop a nickel-catalysed coupling of aryl boronic acids with acid fluorides15–17, which are formed in situ from readily available carboxylic acids18–22. This combination of catalyst and electrophile enables a mechanistic manifold in which a ‘transmetallation-active’ aryl nickel fluoride intermediate is generated directly in the catalytic cycle13,16. As such, this transformation does not require an exogenous base and is applicable to a wide range of base-sensitive boronic acids and biologically active carboxylic acids.
- Malapit, Christian A.,Bour, James R.,Brigham, Conor E.,Sanford, Melanie S.
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p. 100 - 104
(2018/11/25)
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- Oxidative Cross-Coupling of Boron and Antimony Nucleophiles via Palladium(I)
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The use of an isolatable, monomeric Pd(I) complex as a catalyst for the oxidative cross-coupling of aryl-antimony and aryl-boron nucleophiles is reported. This reaction tolerates a wide variety of substrates, with >20:1 selectivity for cross-coupled products. This strategy offers a new approach to achieving the selective cross-coupling of nucleophiles.
- Simpson, Quillon,Sinclair, Matthew J. G.,Lupton, David W.,Chaplin, Adrian B.,Hooper, Joel F.
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supporting information
p. 5537 - 5540
(2018/09/21)
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- One-step highly selective borylation/Suzuki cross-coupling of two distinct aryl bromides in pure water
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A Na2PdCl4-catalysed B2(OH)4-mediated direct cross-coupling of two distinct aryl bromides in pure water is described. This one-step borylation/Suzuki method exhibits an outstanding cross-coupling selectivity and no tendency to produce homocoupling products, therefore leading to biaryls and heterobiaryls in moderate to good yields. Moreover, the reaction has high regio-selectivity and can be scaled-up. Using such a simple, economical and practical protocol, the unsymmetrical diarylation of 3,5-dibromopryidine is achieved.
- Xu, Shan Dong,Sun, Fang Zhou,Deng, Wei Hang,Hao, Han,Duan, Xin Hong
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supporting information
p. 16464 - 16468
(2018/10/24)
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- One-pot synthesis of 2,3-disubstituted benzofurans from 2-chlorophenols using palladium–dihydroxyterphenylphosphine catalyst
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2,3-Disubstituted benzofurans possessing 2-hydroxyphenyl moiety at the C-3 position were synthesized from readily available 2-chlorophenols and terminal alkynes by hydroxy-directed ortho-Sonogashira coupling and subsequent oxypalladation/reductive elimina
- Yamaguchi, Miyuki,Ozawa, Hayato,Katsumata, Haruka,Akiyama, Tomoyo,Manabe, Kei
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supporting information
p. 3175 - 3178
(2018/07/15)
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- Catalytic Activation of Trimethylsilylacetylenes: A One-Pot Route to Unsymmetrical Acetylenes and Heterocycles
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For the synthesis of unsymmetrical acetylenes, a Sonogashira coupling-deprotection-Sonogashira coupling reaction sequence is often used. Removal of protecting groups requires harsh conditions or an excess of difficult to handle and expensive reagents. Herein, we disclose a novel catalytic method for the selective deprotection of trimethylsilylacetylenes in Sonogashira reaction. The reagent hexafluorosilicic acid, an inexpensive nontoxic compound, was used to promote the selective desilylation. This method enables the efficient synthesis of unsymmetric acetylenes with other silylated functional groups present. Further possibilities of the method were explored by synthesis of heterocycles.
- Lasányi, Dániel,Mészáros, ádám,Novák, Zoltán,Tolnai, Gergely L.
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p. 8281 - 8291
(2018/06/11)
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- Visible light mediated desilylative C(sp2)-C(sp2) cross-coupling reactions of arylsilanes with aryldiazonium salts under Au(i)/Au(iii) catalysis
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Desilylative C(sp2)-C(sp2) cross-coupling reactions of arylsilanes with aryldiazonium salts under Au(i)/photoredox catalysis have been reported. The addition of Cu-salts as catalysts was found to be crucial for the success of this tr
- Chakrabarty, Indradweep,Akram, Manjur O.,Biswas, Suprakash,Patil, Nitin T.
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supporting information
p. 7223 - 7226
(2018/07/03)
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- Palladium-Catalyzed Regioselective C-2 Arylation of Benzofurans with N′-Acyl Arylhydrazines
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A novel ligand-free palladium-catalyzed C-2 arylation of benzofurans has been developed using N′-acyl arylhydrazines as the coupling partners and TEMPO as an oxidant. This protocol features a wide functional-group tolerance and highly regioselective products with good to excellent yields.
- Cao, Jun,Chen, Zi-Li,Li, Shu-Min,Zhu, Gao-Feng,Yang, Yuan-Yong,Wang, Cong,Chen, Wen-Zhang,Wang, Jian-Ta,Zhang, Ji-Quan,Tang, Lei
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p. 2774 - 2779
(2018/06/21)
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- Unexpected one-step synthesis of 3-benzoyl-2-phenylbenzofurans under Wittig conditions
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The reaction of 2-hydroxybenzyltriphenylphosphonium bromide with substituted benzoyl chlorides under Wittig conditions, led to 2-phenylbenzofuran derivatives 4a–p and the unexpected formation of 3-benzoyl-2-phenylbenzofuran derivatives 5a–p. Benzoyl chlorides possessing electron-withdrawing groups afforded 3-benzoyl-2-phenylbenzofuran derivatives in higher yields than those with electron-donating groups. This reaction represents a simple and regioselective, one-pot route towards the preparation of deactivated 3-benzoyl-2-phenylbenzofuran compounds which are difficult to obtain by the direct acylation of 2-phenylbenzofurans.
- Begala, Michela,Caboni, Pierluigi,Matos, Maria Jo?o,Delogu, Giovanna Lucia
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p. 1711 - 1714
(2018/04/10)
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- Palladium/Copper Dual Catalysis for the Cross-Coupling of Aryl(trialkyl)silanes with Aryl Bromides
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Whereas aryl(trialkyl)silanes are considered to be ideal organometallic reagents for cross-coupling reactions owing to their stability, low toxicity, solubility, and easy accessibility, they are generally inert under typical cross-coupling conditions. Disclosed herein is a palladium/copper catalytic system that enables the cross-coupling of trimethyl, triethyl, tert-butyldimethyl, and triisopropyl aryl silanes with aryl bromides. This process is applicable to the sequential C?H and C?Si bond arylation of thiophenes and the synthesis of poly(thiophene–fluorene)s.
- Komiyama, Takeshi,Minami, Yasunori,Furuya, Yuki,Hiyama, Tamejiro
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supporting information
p. 1987 - 1990
(2018/02/10)
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- Hydrazone-Pd-catalyzed direct intermolecular reaction of: O -alkynylphenols with allylic acetates
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We found that the hydrazone-Pd-catalyzed direct intermolecular reaction of o-alkynylphenols with allylic acetates afforded the corresponding 2-substituted-3-allylbenzofuran derivatives. This reaction proceeded smoothly at room temperature using a hydrazon
- Watanabe, Kohei,Mino, Takashi,Ishikawa, Eri,Masuda, Chihiro,Yoshida, Yasushi,Sakamoto, Masami
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p. 575 - 584
(2018/02/07)
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- Hypervalent Iodine(III)-Catalyzed Synthesis of 2-Arylbenzofurans
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An alternative route for the synthesis of 2-arylbenzofurans is described by iodine(III)-catalyzed oxidative cyclization of 2-hydroxystilbenes using 10 mol% (diacetoxyiodo)benzene [PhI(OAc) 2 ] as catalyst in the presence of m -chloroperbenzoic acid. The 2-arylbenzofurans were isolated in good to excellent yields.
- Singh, Fateh V.,Mangaonkar, Saeesh R.
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p. 4940 - 4948
(2018/12/14)
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- Organic transformations catalyzed by palladium nanoparticles on carbon nanomaterials
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Abstract: An efficient C–C bond coupling reactions (Suzuki–Miyaura and Glaser) catalyzed by PdO/GO nano-catalyst is presented. In addition, PdO/MWCNT nano-catalyst-mediated domino one-pot synthesis of 2-alkyl/2-aryl benzofurans has been accomplished from 2-iodophenols and terminal alkynes. The formation of benzofurans proceeds through intermolecular Sonogashira reaction followed by intramolecular nucleophilic addition of internal hydroxyl group onto the acetylenic bond. The catalyst PdO/GO has been reused successfully, with nearly no loss of activity up to 5 cycles. Graphical Abstract: : Synopsis: An efficient PdO/GO and PdO/MWCNT nanocatalysts have been developed for C–C coupling reactions like Suzuki and Glaser coupling reactions, multi-catalytic one-pot synthesis of 2-aryl, 2-alkyl benzofurans staring from 2-iodophenols and terminal alkynes. The protocol involves formation of benzofuran derivatives, i.e., Sonogashira reaction followed by 2-ethynyl phenol cyclization. [Figure not available: see fulltext.]
- Lakshminarayana, Bhairi,Mahendar, Lodi,Chakraborty, Jhonti,Satyanarayana, Gedu,Subrahmanyam, Ch
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- 1,2,3-Triazole based bisphosphine, 5-(diphenylphosphanyl)-1-(2-(diphenylphosphanyl)-phenyl)-4-phenyl-1: H -1,2,3-triazole: An ambidentate ligand with switchable coordination modes
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The reaction of 1-(2-bromophenyl)-4-phenyl-1H-1,2,3-triazole (1) with Ph2PCl yielded bisphosphine, 5-(diphenylphosphanyl)-1-(2-(diphenylphosphanyl)phenyl)-4-phenyl-1H-1,2,3-triazole (2). Bisphosphine 2 exhibits ambidentate character in either the κ2-P,N or κ2-P,P coordination mode. Treatment of 2 with [M(CO)4(piperidine)2] (M = Mo and W) yielded κ2-P,N and κ2-P,P coordinated Mo0 and W0 complexes [M(CO)4(2)] [M = W-κ2-P,N (4); Mo-κ2-P,P (5); W-κ2-P,P (6)] depending on the reaction conditions. Formation and stability of κ2-P,P coordinated Mo0 and W0 complexes were assessed by time dependent 31P{1H} NMR experiments and DFT studies. The complex 4 on treatment with [AuCl(SMe2)] afforded the hetero-bimetallic complex [μ-PN,P-{o-Ph2P(C6H4){1,2,3-N3C(Ph)C(PPh2AuCl)}-κ2-P,N}W(CO)4] (7). The 1:1 reaction between 2 and [CpRu(PPh3)2Cl] yielded [(η5-C5H5)RuCl{o-Ph2P(C6H4){1,2,3-N3C(Ph)C(PPh2)}}-κ2-P,P] (8), whereas the similar reaction with [Ru(η6-p-cymene)Cl2]2 in a 2:1 molar ratio produced a cationic complex [(η6-p-cymene)RuCl{o-Ph2P(C6H4){1,2,3-N3C(Ph)C(PPh2)}}-κ2-P,N]Cl (9). Similarly, treatment of 2 with [M(COD)(Cl)2] (M = Pd and Pt) in a 1:1 molar ratio yielded PdII and PtII complexes [{o-Ph2P(C6H4){1,2,3-N3C(Ph)C(PPh2)}-κ2-P,P}PdCl2] (10) and [{o-Ph2P(C6H4){1,2,3-N3C(Ph)C(PPh2)}-κ2-P,P}PtCl2] (11). The reaction of 2 with 2 equiv. of [AuCl(SMe2)] afforded [Au2Cl2{o-Ph2P(C6H4){1,2,3-N3C(Ph)C(PPh2)}}-μ-P,P] (12). Most of the complexes have been structurally characterized. Palladium complex 10 shows excellent catalytic activity towards Cu-free Sonogashira alkynylation/cyclization reactions.
- Radhakrishna, Latchupatula,Pandey, Madhusudan K.,Balakrishna, Maravanji S.
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p. 25704 - 25718
(2018/07/31)
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- Recyclable Pd/CuFe2O4 nanowires: A highly active catalyst for C-C couplings and synthesis of benzofuran derivatives
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Pd/CuFe2O4 nanowire-catalyzed cross coupling transformations are described. Notably, these reactions showed excellent functional group tolerance. Further, the protocol is applied to a one-pot synthesis of benzofurans via a Sonogashira coupling and intramolecular etherification sequence. The catalyst was reused and found to maintain its activity and stability.
- Lakshminarayana, Bhairi,Chakraborty, Jhonti,Satyanarayana,Subrahmanyam, Ch.
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p. 21030 - 21039
(2018/06/13)
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- Nickel-Catalyzed Cross-Coupling Reaction of Aryl Sulfoxides with Arylzinc Reagents: When the Leaving Group is an Oxidant
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Nickel-catalyzed Negishi-type cross-coupling of aryl methyl sulfoxides with arylzinc reagents has been developed. By consuming the catalyst-oxidizing methanesulfenate anion through oxidative homocoupling of the arylzinc reagent, smooth catalyst turnover c
- Yamamoto, Keita,Otsuka, Shinya,Nogi, Keisuke,Yorimitsu, Hideki
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p. 7623 - 7628
(2017/11/14)
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- Design, Synthesis, and Application of Polymer-Supported Silicon-Transfer Agents for Cross-Coupling Reactions with Organolithium Reagents
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The initial design, synthesis, and validation of polymer-supported siloxane transfer agents have been achieved that permit the direct use of organolithium reagents in the palladium-catalyzed cross-coupling reactions. Through rational design, two generations of polymer support were developed that significantly simplify product purification and the transfer agent recycling.
- Nguyen, Minh H.,O'Brien, Kevin T.,Smith, Amos B.
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p. 11056 - 11071
(2017/10/27)
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- Hydrazone–Cu-Catalyzed Suzuki–Miyaura-Type Reactions of Dibromoalkenes with Arylboronic Acids
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We have found that Suzuki–Miyaura-type reactions of dibromoalkenes with arylboronic acids using a hydrazone–Cu catalyst system proceeded smoothly under mild conditions to afford the corresponding internal alkyne derivatives in good yields. Furthermore, we also succeeded in the synthesis of o-allyloxy(ethynyl)benzene derivatives, which are known to be effective precursors of various heterocyclic compounds, through this reaction.
- Watanabe, Kohei,Mino, Takashi,Hatta, Chikako,Ishikawa, Eri,Yoshida, Yasushi,Sakamoto, Masami
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p. 3612 - 3619
(2017/07/22)
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- Photoinduced Gold-Catalyzed Domino C(sp) Arylation/Oxyarylation of TMS-Terminated Alkynols with Arenediazonium Salts
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A selective and convenient synthesis of tri- and tetrasubstituted α,β-unsaturated ketones, as well as 2,3-diarylbenzofurans has been developed with the aid of light and taking advantage of a cooperative gold/photoredox-catalyzed 2-fold arylation reaction of TMS-terminated alkynols. The reaction of 3-(trimethylsilyl)prop-2-yn-1-ols was competent to generate diarylated α,β-unsaturated ketones; whereas the photoredox sequence involving 2-[(trimethylsilyl)ethynyl]phenol exclusively afforded 2,3-diarylbenzofurans. The reaction of terminal alkynes proceeded in poor yields while the use of bulkier silyl groups, such as TIPS, resulted unproductive. Apparently, the C(sp) arylation reaction is the first event on the domino bis-arylative sequence. These results could be explained through the intermediation of arylgold(III) species and several single electron transfer processes.
- Alcaide, Benito,Almendros, Pedro,Busto, Eduardo,Lázaro-Milla, Carlos
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p. 2177 - 2186
(2017/02/26)
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- Synthesis of substituted benzofurans and indoles by Zn-catalyzed tandem Sonogashira-cyclization strategy
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Transition metal catalyzed cross-coupling reactions are one of the predominant strategies for the construction of heterocyclic structures which possess wide applications in the synthesis of natural products, pharmaceuticals, polymers, etc. Due to the vast importance of substituted benzofurans and indoles, numerous synthetic methodologies have been introduced for their synthesis. Among these methods, transition metal catalyzed cyclization reactions possess a unique position. In this manuscript, we disclose the first and efficient zinc-catalyzed protocol for the cyclization reactions of alkynes with 2-iodophenol and 2-iodoaniline leading to benzofurans and indoles respectively via a tandem Sonogashira coupling-cyclization process. Among the different metal catalysts, zinc has enormous potential due to its great availability, non-toxicity, eco-friendly and inexpensive nature. Zn(II) with N,N′-dimethylethylenediamine represents a suitable and efficient catalytic system for the desired tandem CC coupling-cyclization reactions, and a broad spectrum of functional groups are tolerated during the catalysis. A variety of substituted benzofurans and indoles have been successfully prepared in moderate to good yields under this new protocol.
- Thankachan, Amrutha P.,Sindhu, Kallikkakam S.,Ujwaldev, Sankuviruthiyil M.,Anilkumar, Gopinathan
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supporting information
p. 536 - 540
(2017/01/16)
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- Synthesis of Benzofurans and Indoles from Terminal Alkynes and Iodoaromatics Catalyzed by Recyclable Palladium Nanoparticles Immobilized on Siliceous Mesocellular Foam
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Herein, we report on the utilization of a heterogeneous catalyst, consisting of Pd nanoparticles supported on a siliceous mesocellular foam (Pd0-AmP-MCF), for the synthesis of heterocycles. Reaction of o-iodophenols and protected o-iodoanilines with acetylenes in the presence of a Pd nanocatalyst produced 2-substituted benzofurans and indoles, respectively. In general, the catalytic protocol afforded the desired products in good to excellent yields under mild reaction conditions without the addition of ligands. Moreover, the structure of the reported Pd nanocatalyst was further elucidated with extended X-ray absorption fine-structure spectroscopy, and it was proven that the catalyst could be recycled multiple times without significant loss of activity.
- Bruneau, Alexandre,Gustafson, Karl P. J.,Yuan, Ning,Tai, Cheuk-Wai,Persson, Ingmar,Zou, Xiaodong,B?ckvall, Jan-E.
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supporting information
p. 12886 - 12891
(2017/09/25)
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- Catalytic Intramolecular Wittig Reaction Based on a Phosphine/Phosphine Oxide Catalytic Cycle for the Synthesis of Heterocycles
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The catalytic intramolecular Wittig reactions of carbonyl-containing bromides are reported. The R3PO byproducts participate in the catalytic cycle; therefore, the Wittig reaction can be accomplished with only a catalytic amount of organophosphorus reagent. The reaction has also been applied to the efficient and selective synthesis of isoquinolin-1(2H)-ones, indoles, 2,3-dihydro-1H-2-benzazepin-1-ones, benzofurans, and 1,2-dihydroquinolines with a catalytic amount of phosphine oxide (0.1 equiv.) and a tetramethyldisiloxane/titanium isopropoxide [TMDS/Ti(OiPr)4] reductant system (yields: 35–88 %).
- Wang, Long,Sun, Mei,Ding, Ming-Wu
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p. 2568 - 2578
(2017/05/19)
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- Dual Photoredox/Gold Catalysis Arylative Cyclization of o-Alkynylphenols with Aryldiazonium Salts: A Flexible Synthesis of Benzofurans
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A new method for the arylative cyclization of o-alkynylphenols with aryldiazonium salts via dual photoredox/gold catalysis is described. The reaction proceeds smoothly at room temperature in the absence of base and/or additives and offers an efficient app
- Xia, Zhonghua,Khaled, Omar,Mouriès-Mansuy, Virginie,Ollivier, Cyril,Fensterbank, Louis
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p. 7182 - 7190
(2016/08/30)
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