- Interface coassembly of mesoporous MoS2 based-frameworks for enhanced near-infrared light driven photocatalysis
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The three-dimensional porous Fe3O4@Cu2-xS-MoS2 framework is reported for the first time. The as-prepared 3D framework exhibits good structural stability, high surface area, enhanced adsorption capacity to substrates, and strong absorption in the NIR range. As a result, such hybrid frameworks exhibit excellent NIR-light photocatalytic activity and stable cycling for the direct arylation of heteroaromatics at room temperature.
- Zhi, Lihua,Zhang, Haoli,Yang, Zhengyin,Liu, Weisheng,Wang, Baodui
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- Facile C–H arylation using catalytically active terminal sulfurs of 2 dimensional molybdenum disulfide
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The first methodology of C–H arylation of heteroarene via 2D transition metal dichalcogenides that have catalytically active edge functional groups was described. The terminal sulfur groups could effectively catalyze a formation of an azo-linked intermediate with aryl diazonium salts, leading to produce heteroarenes with good yields. This novel methodology using bulk 2D transition metal dichalcogenides that have catalytically active edge functional groups can apply for various reactions to achieve C–C bond formation in the fields of heterogeneous catalysis that is easily separable, highly reusable, and inexpensive method.
- Hwang, Eunhee,Mi Lee, Sae,Bak, Sora,Min Hwang, Hee,Kim, Hyunjung,Lee, Hyoyoung
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- Gram-scale synthesis of aligned C3N4-polypyrrole heterojunction aerogels with tunable band structures as efficient visible and near infrared light-driven metal-free photocatalysts
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The assembly of aligned porous materials from simple building blocks is of widespread interest for engineering materials with enhanced and synergistic properties. To date, however, how to develop 3D heterojunction aerogels with aligned porosity based on 2D semiconductor materials and 1D conducting polymers for solar energy conversion in the visible and near-infrared (NIR) light region remains a significant challenge. Here a new class of gram-scale 3D aligned heterojunction aerogels of polypyrrole (PPy)/C3N4 nanosheets (NSs) were designed and synthesized by directional freezing of polypyrrole (PPy)/polyvinyl alcohol (PVA) and C3N4 NS aqueous suspension. The synthesis of aligned C3N4-PPy heterojunction aerogels can be achieved on a large scale. The formed aerogel expresses stable and uniform dispersion of the two building blocks, long-range channel aligned structures along the whole monolithic sample, and additional special complementary optical properties between PPy and C3N4 NSs. Based on the above unique structure and optical properties, this novel metal-free heterojunction aerogel exhibits excellent photocatalytic activity and long-term stability for direct arylation of heteroaromatics under visible and near infrared (NIR) light irradiation at room temperature, far exceeding those of the single- and two-component systems. Our work therefore not only provides a new approach to obtain aligned heterojunction aerogels based on metal free semiconductors but also paves a way to develop gram-scale aerogels as a new type of highly efficient visible and NIR light induced heterogeneous photocatalyst.
- Liu, Jian,Wang, Hao,Bai, Jinwei,Li, Tianrong,Yang, Yanmei,Peng, Yong,Wang, Baodui
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- A g-C3N4/rGO nanocomposite as a highly efficient metal-free photocatalyst for direct C-H arylation under visible light irradiation
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Visible light mediated photoredox arylations can proceed under very mild conditions and have therefore become attractive. Nowadays, various metal nanomaterials and metal complexes have been developed as photocatalysts for direct arylation of heteroaromatics. These photocatalysts, however, still suffer from corrosion, high cost, aggregation or poor stability. We report the design and fabrication of a g-C3N4/rGO nanocomposite and demonstrate its excellent activity, high apparent quantum efficiency, and recyclability to catalyze the metal free direct arylation of heteroaromatics under visible light at room temperature. Moreover, the g-C3N4/rGO catalyst can be reused more than five times without significant loss of activity, confirming this catalyst's excellent stability. The present strategy to fabricate a metal-free g-C3N4/rGO nanocomposite for direct C-H arylation open a new avenue towards replacing metal-based catalysts in fine organic synthesis.
- Cai, Xiaohui,Liu, Hanwen,Zhi, Lihua,Wen, Huang,Yu, Ailing,Li, Lianhua,Chen, Fengjuan,Wang, Baodui
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- Synthesis of 2,5-Disubstituted Furans from Sc(OTf)3 Catalyzed Reaction of Aryl Oxiranediesters with γ-Hydroxyenones
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A convenient synthesis of 2,5-disubstituted furan was developed by employing donor-acceptor oxiranes in a new reaction with γ-hydroxyenones. Sc(OTf)3 was found to be the best catalyst, and 2,5-disubstituted furans are obtained in moderate to good yields under mild reaction conditions. The scope of the reaction is quite decent, allowing for the synthesis of disubstituted furans having aryl and heteroaromatic groups.
- Mondal, Keshab,Pan, Subhas Chandra
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- Gold(III) porphyrin-catalyzed cycloisomerization of allenones
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Gold(III) porphyrin-catalyzed cycloisomerization of allenones gave the corresponding furans in good to excellent yields (up to 98%) and with quantitative substrate conversions. By recovering the Au(III) catalyst, a recyclable catalytic system is developed with over 8300 product turnovers attained for the cycloisomerization of 1-phenyl-buta-2,3-dien-1-one. The versatility of the gold(III) porphyrin catalyst was exemplified by its application to the hydroamination and hydration of phenylacetylene in 73% and 87% yield, respectively.
- Zhou, Cong-Ying,Chan, Philip Wai Hong,Che, Chi-Ming
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- Fabrication of Graphitic Carbon Nitride-Based Film: An Emerged Highly Efficient Catalyst for Direct C—H Arylation under Solar Light
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Photoredox C—H bond formation can proceed in aerobic environment under solar light and has therefore become attractive. Nowadays, different types of expensive novel metal complexes and nanomaterials have been urbanized as photocatalysts for direct C—H bon
- Chaubey, Surabhi,Yadav, Rajesh K.,Kim, Tae Wu,Yadav, Tara Chand,Kumar, Abhishek,Dwivedi,Pandey,Singh, Atul P.
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- Synthesis of 3-(4-heteroaryl-phenyl)-8-oxabicyclo[3.2.1]octane-2-carboxylic acid methyl esters
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Cross coupling protocols were applied for the synthesis of 3-(4-heteroaryl-phenyl)-8-oxabicyclo[3.2.1]oct-2-ene-2-carboxylic acid methyl esters. Stille conditions produced the corresponding products in reasonable yields. Samarium iodide reduction of the resulting coupling products produced the 2β-carbomethoxy-3α-aryl-8-oxabicyclo[3.2.1]octane diastereoisomers as the major, and the 2β-carbomethoxy-3β-aryl-8- oxabicyclo[3.2.1]octane diastereoisomer as the minor products. Both diastereomers manifested inhibition of the dopamine (DAT) and serotonin (SERT) transporters, with some selectivity for SERT inhibition.
- Torun, Lokman,Liu, Shanghao,Madras, Bertha K.,Meltzer, Peter C.
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Read Online
- Mild and Robust Stille Reactions in Water using Parts Per Million Levels of a Triphenylphosphine-Based Palladacycle
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An inexpensive and new triphenylphosphine-based palladacycle has been developed as a pre-catalyst, leading to highly effective Stille cross-coupling reactions in water under mild reaction conditions. Only 500–1000 ppm of Pd suffices for couplings involving a variety of aryl/heteroaryl halides with aryl/hetaryl stannanes. Several drug intermediates can be prepared using this catalyst in aqueous nanoreactors formed by 2 wt % Brij-30 in water.
- Takale, Balaram S.,Thakore, Ruchita R.,Casotti, Gianluca,Li, Xaiohan,Gallou, Fabrice,Lipshutz, Bruce H.
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supporting information
p. 4158 - 4163
(2021/02/01)
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- Pyrazole-Mediated C-H Functionalization of Arene and Heteroarenes for Aryl-(Hetero)aryl Cross-Coupling Reactions
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Herein we introduce a transition-metal-free protocol that involves a commercially available, inexpensive pyrazole molecule to conduct C-C cross-coupling reactions at room temperature via a radical pathway. Using this method, an aryldiazonium salt has been coupled to a wide range of arenes and heteroarenes including benzene, mesitylene, thiophene, furan, benzoxazole to result the corresponding biaryl products. The full reaction mechanism is elucidated along with the crystallographic probation of an active initiator species. A potassium-stabilized deprotonated pyrazole steers single-electron transfer to the substrate and behaves as an initiator for the reaction.
- Kundu, Abhishek,Dey, Dhananjay,Pal, Subhankar,Adhikari, Debashis
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p. 15665 - 15673
(2021/11/16)
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- Black phosphorus as a metal-free, visible-light-active heterogeneous photoredox catalyst for the direct C-H arylation of heteroarenes
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Black phosphorus (BP) is for the first time employed as a metal-free, heterogeneous photoredox catalyst for the direct C-H arylation of heteroarenes with aryl diazonium salts. The arylated heteroarenes are obtained in moderate to good yields under visible-light illumination, and the protocol is shown to be applicable for the scale-up synthesis.
- Kalay, Erbay,Kü?ükke?eci, Hüseyin,Kilic, Haydar,Metin, ?nder
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supporting information
p. 5901 - 5904
(2020/06/04)
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- Carbazole based Electron Donor Acceptor (EDA) catalysis for the synthesis of biaryl and aryl-heteroaryl compounds
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A highly regioselective, carbazole based Electron Donor Acceptor (EDA) catalyzed synthesis of biaryl and aryl-heteroaryl compounds is described. Various indole and carbazole derivatives were screened for the Homolytic Aromatic Substitution (HAS) reaction. Tetrahydrocarbazole (THC) was very efficient for the HAS transformation and proceeded via a complex formation between diazonium salt and electron rich tetrahydrocarbazole. The UV-Vis spectroscopy technique has been used to confirm the complex formation. The in situ generated EDA complex even in a catalytic amount is found to be efficient for the Single Electron Transfer (SET) process without any photoactivation. Biaryl compounds, 2-phenylfuran, 2-phenylthiophene, and 2-phenylpyrrole and bioactive compounds such as dantrolene and canagliflozin have been synthesized in moderate to excellent yields.
- Annes, Sesuraj Babiola,Ramesh, Subburethinam,Saravanan, Subramanian,Saritha, Rajendhiran
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supporting information
p. 2510 - 2515
(2020/04/15)
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- METHOD FOR PREPARING SILANE DERIVATIVES FROM FURAN DERIVATIVES IN PRESENCE OF BORANE CATALYST
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The present invention relates to a method for preparing various silane derivatives by subjecting various furan derivatives to hydrosilylation in the presence of a borane catalyst. The method for preparing silane derivatives according to the present invention is a very efficient method for converting, into high value-added silane derivatives, various furan derivatives derived from biomass.
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Paragraph 0161-0163; 0166
(2019/09/06)
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- Phenalenyl Based Aluminum Compound for Catalytic C-H Arylation of Arene and Heteroarenes at Room Temperature
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Main group metal based catalysis has been considered to be a cost-effective alternative way to the transition metal based catalysis, due to the high abundance of main group metals in the Earth's crust. Among the main group metals, aluminum is the most abundant (7-8%) in the Earth's crust, making the development of aluminum based catalysts very attractive. So far, aluminum based compounds have been popularly used as Lewis acids in a variety of organic reactions, but chemical transformation demanding a redox based process has never utilized an Al(III) complex as a catalyst. Herein, we tuned the redox noninnocence behavior of a phenalenyl ligand by coupling with Al(III) ion, which subsequently can store the electron upon reduction with K to carry out direct C-H arylation of heteroarenes/mesitylene at ambient temperature. A mechanistic investigation revealed that a three-electron reduced phenalenyl based triradical aluminum(III) complex plays the key role in such catalysis. The electronic structure of the catalytically active triradical species has been probed using EPR spectroscopy, magnetic susceptibility measurements, and electronic structure calculations using a DFT method.
- Vardhanapu, Pavan K.,Ahmed, Jasimuddin,Jose, Anex,Shaw, Bikash Kumar,Sen, Tamal K.,Mathews, Amita A.,Mandal, Swadhin K.
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p. 289 - 299
(2019/01/10)
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- Perylenequinonoid-catalyzed photoredox activation for the direct arylation of (het)arenes with sunlight
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Naturally occurring perylenequinonoid pigments (PQPs) have attracted considerable attention owing to their excellent properties of photosensitization. They have been widely investigated as an aspect of photophysics and photobiology. However, their applications in photocatalysis are yet to be explored. We report here that sunlight along with 1 mol% cercosporin, which is one of the perylenequinonoid pigments, catalyzes the direct C-H bond arylation of (het)arenes by a photoredox process with good regioselectivity and broad functional group compatibility. Furthermore, a gram-scale reaction with great conversions of substrates was achieved even by a cercosporin-containing supernatant without organic solvent extraction and purification after liquid fermentation. Thus we set up a bridge between microbial fermentation and organic photocatalysis for chemical reactions in a sustainable, environmentally friendly manner.
- Zhang, Shiwei,Tang, Zhaocheng,Bao, Wenhao,Li, Jia,Guo, Baodang,Huang, Shuping,Zhang, Yan,Rao, Yijian
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supporting information
p. 4364 - 4369
(2019/05/10)
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- Redox reactions of small organic molecules using ball milling and piezoelectric materials
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Over the past decade, photoredox catalysis has harnessed light energy to accelerate bond-forming reactions. We postulated that a complementary method for the redox-activation of small organic molecules in response to applied mechanical energy could be dev
- Kubota, Koji,Pang, Yadong,Miura, Akira,Ito, Hajime
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p. 1500 - 1504
(2020/01/08)
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- Molecular Design of Donor-Acceptor-Type Organic Photocatalysts for Metal-free Aromatic C?C Bond Formations under Visible Light
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Metal-free and photocatalytic radical-mediated aromatic C?C bond formations offer a promising alternative pathway to the conventional transition metal-catalyzed cross-coupling reactions. However, the formation of aryl radicals from common precursors such as aryl halides is highly challenging due to their extremely high reductive potential. Here, we report a structural design strategy of donor-acceptor-type organic photocatalysts for visible light-driven C?C bond formations through the reductive dehalogenation of aryl halides. The reduction potential of the photocatalysts could be systematically aligned to be ?2.04 V vs. SCE via a simple heteroatom engineering of the donor-acceptor moieties. The high reductive potential of the molecular photocatalyst could reduce various aryl halides into aryl radicals to form the C?C bond with heteroarenes. The designability of the molecular photocatalyst further allowed the synthesis of a high LUMO (lowest unoccupied molecular orbital) polymer photocatalyst by a self-initiated free radical polymerization without compromising its LUMO level. (Figure presented.).
- Wang, Lei,Byun, Jeehye,Li, Run,Huang, Wei,Zhang, Kai A. I.
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p. 4312 - 4318
(2018/10/02)
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- Mild-Base-Promoted Arylation of (Hetero)Arenes with Anilines
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Transition metal-free radical arylation of heteroarenes is achieved at room temperature by simply adding aqueous sodium carbonate to a solution of the corresponding heteroarene and arenediazonium salt, which can even be formed in situ. Such an easy, inexpensive and mild methodology has been optimized and applied to the expeditious modification of interesting molecular cores like naphthylimide or bisthienylcyclopentenes.
- Monzón, Diego M.,Santos, Tanausú,Pinacho-Crisóstomo,Martín, Víctor S.,Carrillo, Romen
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p. 325 - 333
(2018/01/15)
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- An Iron-Based Long-Lived Catalyst for Direct C?H Arylation of Arenes and Heteroarenes
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Direct C?H arylation of arenes and heteroarenes to biaryls at ambient temperature has been accomplished using a phenalenyl-supported iron(III) catalyst. The present catalyst requires a chemical reductant such as potassium and functions without any light stimulation. C?H arylation of various heteroarenes including pyridine as well as unactivated arene such as benzene delivered good to excellent yield (28 examples, up to 92 %) at room temperature. A combined effort based on experiments and theoretical calculations established that a phenalenyl-based radical species (generated by chemical reduction of the iron(III) coordinated phenalenyl complex) plays key role during the catalysis. Furthermore, this catalyst displayed remarkable stability during the catalysis, as evident from the fact that it was still usable over ten consecutive catalytic runs without losing its catalytic efficiency.
- Chakraborty, Soumi,Ahmed, Jasimuddin,Shaw, Bikash Kumar,Jose, Anex,Mandal, Swadhin K.
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p. 17651 - 17655
(2018/11/10)
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- Merging visible-light photoredox and micellar catalysis: Arylation reactions with anilines nitrosated in situ
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An aqueous photocatalytic system was designed by merging visible-light photoredox catalysis with micellar catalysis. Eosin B, an organic dye, was utilized as the photocatalyst, and Triton X-100 was employed as the surfactant; both are inexpensive and commercially available. This clean and energy-saving catalytic system enables photocatalytic reactions of the diazonium ion generated in situ to proceed smoothly in water without any co-solvents or additives at room temperature.
- Bu, Mei-Jie,Lu, Guo-Ping,Jiang, Jianzhong,Cai, Chun
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p. 3728 - 3732
(2018/08/12)
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- Continuous Visible-Light Photoflow Approach for a Manganese-Catalyzed (Het)Arene C?H Arylation
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Manganese photocatalysts enabled versatile room-temperature C?H arylation reactions by means of continuous visible-light photoflow, thus allowing for efficient C?H arylations in 30 minutes with ample scope. The robustness of the manganese-catalyzed photoflow strategy was shown by visible light-induced gram-scale synthesis, clearly outperforming the batch performance.
- Liang, Yu-Feng,Steinbock, Ralf,Yang, Long,Ackermann, Lutz
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supporting information
p. 10625 - 10629
(2018/08/01)
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- Electrolytic cross-Coupling of arenediazonium salts and heteroarenes
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The cathodic reduction-induced cross-coupling of arenediazonium salts and heteroarenes was employed to prepare heterobiaryl derivatives. This reaction is attractive because it allows the direct arylation of an aromatic C-H bond in a heteroarene derivative. A radical chain mechanism appears to be involved.
- Hata, Dai,Tobisu, Mamoru,Amaya, Toru
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supporting information
p. 1749 - 1751
(2018/11/27)
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- Polyaniline-Induced Arylation with Arenediazonium Salts Derived from Anilines
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A catalytic amount of a reduced form of polyaniline (a redox-active π-conjugated polymer) was found to induce C?H direct arylation of (hetero)arenes with arenediazonium salts prepared from anilines with methanesulfonic acid (MeSO3H) and tert-butyl nitrite (tBuONO). The difficult part of this method is the coexistence of an oxidant and a reductant in this sequential diazotization and arylation system; diazotization requires weak oxidants such as alkyl nitrites, whereas the arylation is induced by a reductant. This was achieved by the careful control of the amount of tBuONO (1.0 equivalent) for the diazotization step, and sequential arylation using 5 mol % of the polyaniline. The reaction took place under mild conditions without any metals or strong bases at room temperature, and the amino group is a formal leaving group. The scope of the substrates demonstrates the versatility in the combination of anilines with a variety of functional groups and several (hetero)arenes. Two-directional arylation for the synthesis of an unsymmetrical 1,4-diarylated (furyl and pyrrolyl groups) benzene was achieved, using mono-Boc-protected 1,4-phenylenediamine as a substrate. This shows potential for the synthesis of more complicated oligoarene compounds.
- Hata, Dai,Moriuchi, Toshiyuki,Hirao, Toshikazu,Amaya, Toru
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supporting information
p. 7703 - 7709
(2017/06/06)
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- Sodium Chloride Catalyzed Regioselective Trifluoromethylthiolation of Furans
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Here, we report the catalytic trifluoromethylthiolation of furans employing sodium chloride as an inexpensive, abundant and ecologically friendly catalyst. The developed method exhibits perfect regioselectivity and a high functional group tolerance. Furth
- Ernst, Johannes B.,Rakers, Lena,Glorius, Frank
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supporting information
p. 260 - 268
(2016/12/24)
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- Visible-Light-Promoted Arylation Reactions Photocatalyzed by Bismuth(III) Oxide
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Bismuth(III) oxide has been successfully applied as a photocatalyst in the arylation of heteroarenes with diazonium salts. With a low catalyst loading (1 to 5 mol-%), this cheap and nontoxic semiconductor could efficiently promote the formation of the aryl radical under visible light irradiation. The arylated products are obtained in moderate to good yields, and the process admits straightforward scale-up (10 mmol; 1 mol-% Bi2O3). In two cases, the diazonium salt was generated in situ and used in the photocatalytic arylation in a tandem manner. Besides heteroarenes, Bi2O3 also catalyzed the arylation of differently substituted alkenes and alkynes, thus representing a viable and practical alternative to the more commonly used ruthenium complexes and organic dyes.
- Buglioni, Laura,Riente, Paola,Palomares, Emilio,Pericàs, Miquel A.
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supporting information
p. 6986 - 6990
(2017/12/26)
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- Porphyrin-Catalyzed Photochemical C–H Arylation of Heteroarenes
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Organic dyes are a promising class of photoredox catalysts and offer a meaningful alternative to broadly applied Ru and Ir complexes. We found that porphyrins with tuned physicochemical properties, by tailoring various substituents at the periphery of the
- Rybicka-Jasińska, Katarzyna,K?nig, Burkhard,Gryko, Dorota
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supporting information
p. 2104 - 2107
(2017/04/24)
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- Carbocatalytic reductive coupling reactions: Via electron transfer from graphene to aryldiazonium salt
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A reductive coupling reaction using two-dimensional nanocarbon, i.e., reduced graphene oxide (rGO), as a carbocatalyst and/or a reaction initiator was developed. The radical species on the rGO played an important role in the coupling reaction.
- Morimoto, Naoki,Morioku, Kumika,Suzuki, Hideyuki,Nakai, Yumi,Nishina, Yuta
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supporting information
p. 7226 - 7229
(2017/07/11)
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- Polyaniline-Induced C-H Arylation of Arenes with Arenediazonium Salts
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A reduced form of polyaniline has been shown to induce direct arylation of an arenediazonium salt with an arene (Gomberg-Bachmann reaction) to give the cross-coupling product in moderate to good yields under mild conditions. Various arenediazonium salts and arenes, including heteroarenes such as furans, thiophenes, and pyrroles, are employed for the reaction. The most favorable combination of substrates is an electron-poor arenediazonium salt with an electron-rich heteroarene. Investigation of the mechanism by reactions with radical scavengers and experiments on kinetic isotope effects indicated the occurrence of a radical chain reaction initiated by one-electron reduction of an arenediazonium salt by the polyaniline. Only 1 mol % (based on aniline tetramer) of the polyaniline is required for the cross-coupling reaction to occur. This reaction proceeds under metal-free conditions and with no need for photonic activation.
- Amaya, Toru,Hata, Dai,Moriuchi, Toshiyuki,Hirao, Toshikazu
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p. 16427 - 16433
(2015/11/10)
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- A family of low molecular-weight, organic catalysts for reductive C-C bond formation
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Hydrazines form a new family of low molecular-weight reducing agents for diazonium salts. Using only small amounts of hydrazine catalyst, the coupling of diazonium salts to a variety of reactive partners has been achieved, without the requirement for either metal adjuvants or irradiation with visible or ultraviolet light. The generality of the concept proposed herein as well as its advantages in the preparative scale is outlined and discussed.
- Shaaban, Saad,Jolit, Ana?s,Petkova, Desislava,Maulide, Nuno
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p. 13902 - 13905
(2015/09/15)
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- Unexpected dual role of titanium dioxide in the visible light heterogeneous catalyzed C-H arylation of heteroarenes
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The direct arylation of heteroaromatics with an easily accessible and recyclable, heterogeneous TiO2 catalyst and visible light was developed. Electron-rich as well as electron-poor heteroarenes could be applied in this transformation, and the corresponding products were isolated in very good yields. Azoethers were detected as reactive intermediates, and the unexpected role of TiO2 in their formation as well as reaction was established.
- Zoller, Jochen,Fabry, David C.,Rueping, Magnus
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p. 3900 - 3904
(2015/06/16)
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- Iodo-Bodipys as visible-light-absorbing dual-functional photoredox catalysts for preparation of highly functionalized organic compounds by formation of C-C bonds via reductive and oxidative quenching catalytic mechanisms
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Iodo-Bodipys were used as organic catalysts for three different photoredox catalytic organic reactions, i.e. the aza-Henry reaction of tetrahydroisoquinoline, oxidation/[3 + 2] cycloaddition/oxidative aromatization tandem reaction between tetrahydroisoquinolines and maleimides, and C-H arylation of heteroarenes with diazonium salts. The organic photocatalysts act as either electron acceptors (reductive quenching) or electron donors (oxidative quenching) in the single electron transfer (SET) of the catalytic cycles. Different from the widely used Ru(bpy)3[PF6]2, Ir(ppy)3, or halo-xanthane photocatalysts (Eosin Y or Rose Bengal), the new organic photocatalysts show strong absorption of visible light and long-lived triplet excited states, which are beneficial for SET, a crucial step for photoredox catalytic organic reactions. Moreover, the molecular structures of the new photocatalysts can be easily modified, as a result the absorption wavelength of the photocatalysts was readily tuned from 529 nm to 630 nm. The three different types of organic reactions are accelerated with the new organic photocatalysts (typical reaction times 1-2 h) compared to that catalyzed by Ru(bpy)3[PF6]2 or Ir(ppy)3 (reaction time: 12-72 h). The C-H arylation of thiophene with phenyl diazonium salts was used to prepare new Bodipy derivatives that show large Stokes shift. Our results are useful for designing of new organic catalysts for photoredox catalytic organic reactions to prepare highly functionalize organic compounds.
- Huang, Ling,Zhao, Jianzhang
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p. 23377 - 23388
(2013/11/19)
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- Sensitized photografting of diazonium salts by visible light.
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Visible irradiation of a gold surface dipped into a solution of diversely substituted aryldiazonium salts in the presence of a photosensitizer (Ru(bipy)32+ or eosinY) leads to a modification of the surface by attached aryl groups. A grafted nanometer thick polyphenylene film is obtained. The reaction is extended to a polyvinylchloride (PVC) surface. The mechanism proposed for the formation of this film involves the formation of an aryl radical that reacts with the surface and then with the first grafted aryl group. The film is characterized by infrared reflection absorption spectroscopy (IRRAS), X-ray photoelectron spectroscopy (XPS), water contact angles, and ellipsometry.
- Bouriga, Meriem,Chehimi, Mohamed M.,Combellas, Catherine,Decorse, Philippe,Kanoufi, Frederic,Deronzier, Alain,Pinson, Jean
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- Assisted tandem catalytic RCM-aromatization in the synthesis of pyrroles and furans
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An assisted tandem catalytic transformation of diallyl amines and diallyl ethers into N-aryl pyrroles and furans, respectively, is described. The sequence relies on ring closing metathesis followed by dehydrogenation of the initially formed dihydropyrroles and dihydrofurans. Both steps are Ru-catalyzed, but the sequence requires only one precatalyst, because conversion of the metathesis catalyst into the dehydrogenation catalyst is achieved in situ, triggered by the oxidant tert-butyl hydroperoxide.
- Schmidt, Bernd,Krehl, Stefan,Jablowski, Eric
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supporting information; experimental part
p. 5119 - 5130
(2012/08/07)
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- Metal-free, visible-light-mediated direct C-H arylation of heteroarenes with aryl diazonium salts
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Visible light along with 1 mol % eosin Y catalyzes the direct C-H bond arylation of heteroarenes with aryl diazonium salts by a photoredox process. We have investigated the scope of the reaction for several aryl diazonium salts and heteroarenes. The general and easy procedure provides a transition-metal-free alternative for the formation of aryl-heteroaryl bonds.
- Hari, Durga Prasad,Schroll, Peter,Koenig, Burkhard
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supporting information; experimental part
p. 2958 - 2961
(2012/04/04)
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- Direct C-H bond arylation of (Hetero)arenes with Aryl and heteroarylboronic acids
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A novel microwave-promoted protocol mediated by Mn(OAc)3 was developed for the single-electron-transfer oxidative direct C-H bond arylation of (hetero)arenes with aryl and hetero-arylboronic acids. Various electron-deactivated and electron-rich heteroarenes and benzene underwent successfully the direct arylation in this general process. The use of slight excess of heteroarene or benzene in this method was found to be sufficient. Georg Thieme Verlag Stuttgart New York.
- Guchhait, Sankar K.,Kashyap, Maneesh,Saraf, Shuddham
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experimental part
p. 1166 - 1170
(2010/06/11)
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- Utilization of sequential palladium-catalyzed cross-coupling reactions in the stereospecific synthesis of trisubstituted olefins
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A stereospecific synthesis of the drug-candidate 1 is described. The synthetic sequence, aimed at accomplishing modularity and cost savings, features a series of organometallic steps to afford stereospecifically the desired trisubstituded olefin active pharmaceutical ingredient. Key developments consist of a mild Sonogashira reaction of aryl bromide 7a with the polymerization prone propargyl alcohol and a stereospecific hydroalumination, Zn/Al exchange, and Pd-catalyzed cross-coupling sequence facilitated by the commercially available PEPPSI catalyst.
- Houpis, Ioannis N.,Shilds, Didier,Nettekoven, Ulrike,Schnyder, Anita,Bappert, Erhart,Weerts, Koen,Canters, Martine,Vermuelen, Wim
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experimental part
p. 598 - 606
(2010/04/22)
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- Efficient one-pot synthesis of 2-substituted furans from 3,3-diethoxypropyne and aldehydes using a Ti(O-i-Pr)4/2i-PrMgCl reagent
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A new, efficient and direct synthetic method for synthesizing 2-substituted furans using titanium-alkyne complex from easily preparable lithium propargyl alcohol derivatives derived from commercially available 3,3-diethoxypropyne, n-butyllithium and aldehydes by a Ti(O-i-Pr)4/2 i-PrMgCl reagent in 68-85percent yields.
- Eom, Deok Ki,Choi, Seong Jib,An, Duk Keun
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p. 1141 - 1146
(2008/02/08)
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- Preparation of furans by palladium-catalyzed reaction of acylchromates and propargylic tosylates
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Substituted furans are prepared by the palladium-catalyzed reaction of propargylic tosylates with acylchromates. The reaction is initiated by the oxidative additiion of propagylic tosylates to palladium(O) complexes to give 1,2-propadienylpalladium(II) co
- Nakamura, Masaki,Yamane, Motoki,Sakurai, Hidehiro,Narasaka, Koichi
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p. 333 - 345
(2007/10/03)
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- Generation of aryl radicals from arylboronic acids by manganese(III) acetate: Synthesis of biaryls and heterobiaryls
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The efficient generation of aryl radicals from arylboronic acids by manganese(III) acetate is described. In aromatic solvents, in situ generated aryl radicals afford the corresponding biaryls in very good yields. This method works selectively, and yields
- Demir, Ayhan S.,Reis, Oemer,Emrullahoglu, Mustafa
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p. 578 - 580
(2007/10/03)
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- Manganese(III) acetate-mediated oxidative coupling of phenylhydrazines with furan and thiophene: A novel method for hetero biaryl coupling
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A convenient new method for the arylation of furan and thiophene with arylhydrazine and manganese(III) acetate is described. Oxidation of arylhydrazines with Mn(III) acetate in furan or thiophene affords the corresponding 2-aryl-substituted furans and thiophenes in good yield using commercially available materials; access to 2-substituted heterobiaryls works selectively, and coupling occurs with loss of the hydrazine moiety.
- Demir, Ayhan S.,Reis, ?mer,Emrullaho?lu, Mustafa
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p. 8055 - 8058
(2007/10/03)
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- A convenient synthesis of polysubstituted phenylphenols from substituted anilines
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2' and 4'-Substituted arylfurans react with DMAD in the presence of Lewis acid to afford Diels-Alder adducts with good yields; a subsequent spontaneous or an acid-induced ?-elimination leads to polysubstituted phenylphenols.
- Maggiani, Alain,Tubul, Ariette,Brun, Pierre
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p. 631 - 633
(2007/10/03)
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- Phase-Transfer-Catalyzed Gomberg-Bachmann Synthesis of Unsymmetrical Biarenes: A Survey of Catalysts and Substrates
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Two problems have hindered the Gomberg-Bachmann (GB) and Pschorr reactions of arenediazonium cations: the instability of the arenediazonium salts and side reactions.Arenediazonium tetrafluoroborate and hexafluorophosphate salts can be prepared in high yield and purity and can be stored safely.Unfortunately, these salts are insoluble in most nonpolar organic solvents.Crown ether complexation or other phase-transfer (pt) catalytic methodology can ameliorate this situation, and reactions conducted by the approaches outlined herein often afforded coupling or cyclization products in high yield and corresponding purity.The use of crown ethers, quarternary 'onium salts, lipophilic carboxylic acid salts, and even the polar cosolvent acetonitrile increase the utility of the ptGB reaction dramatically.Sixty examples of couplings are reported along with an assessment of selectivities.A number of examples are also presented of phase-transfer-type Pschorr cyclizations.In the latter case, the use of potassium superoxide, KO2, is introduced to suppress indazole formation.
- Beadle, James R.,Korzeniowsky, Stephen H.,Rosenberg, David E.,Garcia-Slanga, Blanche J.,Gokel, George W.
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p. 1594 - 1603
(2007/10/02)
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- ELECTROOXIDATION OF 2-ARYLFURANS
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Electrochemical methoxylation of 2-phenylfuran (I) and 2-(4-nitrophenyl)furan (VI) proceeded anomalously, affording 5-methoxy-2-phenylfuran (XI) and 5-methoxy-2-(4-nitrophenyl)furan (XIII), respectively. 2-Phenyl-5-methylfuran (II) and methyl-2-(2-methylphenyl)-3-furoate (VIII) behaved normally giving the respective 2,5-dimethoxy-2,5-dihydrofuran derivatives XII and XIV.The suggested ECNECB mechanism of the anomalous methoxylation was confirmed by methoxylation of compound II, in which the methyl group hinders the last CB step, and also of compound VIII in whichthe aromaticity is suppresed by forced deviation from planarity.Forced deviation from planarity was moreover studied also on 2-(4-methylphenyl)furan (III), 5-methyl-2-(2-methylphenyl)furan (IV) and 3,5-dimethyl-2-(2-methylphenyl)furan (V) as model compounds.For all the derivatives the INDO charges were calculated and correlated with the 1H- and 13C-NMR spectra.The experimental electronic spectra were correlated with the theoretical ones (INDO-S-CI).All results obtained confirm the suggested mechanism.
- Janda, Miroslav,Srogl, Jan,Dvorakova, Hana,Dvorak, Dalimil,Stibor, Ivan
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p. 906 - 916
(2007/10/02)
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- BROMINATION OF ARYLFURANS
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The bromination of 2-arylfurans has been studied.The structures of the compounds obtained have been determined with the aid of NMR spectra.
- Oleinik, A.F.,Solov'eva, N.P.,Turchin, K.F.,Sheinker, Yu.N.,Novitskii, K.Yu.,et al.
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p. 334 - 338
(2007/10/02)
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