- Synthesis of Substituted Thiophenes through Dehydration and Heterocyclization of Alkynols
-
A protocol was described for obtaining a variety of substituted thiophenes with functional potential via metal-free dehydration and sulfur cyclization of alkynols with elemental sulfur (S8) or EtOCS2K in moderate-to-good yields. The method provides the base-free generation of a trisulfur radical anion (S3?-) and its addition to alkynes as an initiator. This research broadens the applications of S3?-in the synthesis of sulfur-containing heterocycles.
- Chen, Lu,Chen, Zebin,Huang, Yubing,Ji, Xiaoliang,Li, Jiaming,Li, Jian,Li, Yibiao,Liu, Qiang,Liu, Yang
-
supporting information
p. 3555 - 3566
(2022/03/14)
-
- Synthesis and fast switching electrochromic properties of conjugated microporous polymers based on carbazole-thiophene derivatives
-
To study the relationship between chemical structure and switching time of electrochromic polymer materials, four star-shape monomers, 3,6-di(thiophen-2-yl)-9-(4-(thiophen-2-yl)phenyl)-9H-carbazole (M1), 2,7-di(thiophen-2-yl)-9-(4-(thiophen-2-yl)phenyl)-9H-carbazole(M2), 3,6-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9-(4-(thiophen-2-yl) phenyl)-9H-carbazole(M3) and 2,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9-(4-(thiophen-2-yl)phenyl)-9H-carbazole(M4) were designed and synthesized successfully, their chemical structure were characterized by nuclear magnetic resonance (NMR) and high resolution mass spectrum (HRMS). Their resulting polymer films could be obtained by electropolymerization, all the polymer films showed well-defined electrochemical properties except for PM2, the PM3 and PM4 revealed wider electrochemical response due to the existence of EDOT units. The surface morphology results indicated that all the polymer films consisted of many particles, and PM1 and PM3 showed smaller grain than that of PM2 and PM4 due to the different aggregation structure, which might benefit for the transport of doped ions. Electrochromic kinetic studies confirmed such hypothesis furtherly, PM3 revealed fastest switching time (Tc: 0.72 s and Tb: 0.61 s), the reason could be explained by electrochemical impedance spectroscopy, which indicated that PM3 possessed the smallest charge transfer resistance (Rct) and fastest diffusion coefficient values at the oxidation state. We hope these findings will provide a little effect on designing and synthesizing high performance electrochromic materials and devices.
- Hu, Bin,Hu, Xian-qiu,Jin, Lin,Luo, Wen,Zhang, Bo,Zhang, Xin-lei
-
-
- Fabrication of Graphitic Carbon Nitride-Based Film: An Emerged Highly Efficient Catalyst for Direct C—H Arylation under Solar Light
-
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.
-
p. 633 - 639
(2021/02/12)
-
- Pyrazole-Mediated C-H Functionalization of Arene and Heteroarenes for Aryl-(Hetero)aryl Cross-Coupling Reactions
-
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
-
p. 15665 - 15673
(2021/11/16)
-
- Black phosphorus as a metal-free, visible-light-active heterogeneous photoredox catalyst for the direct C-H arylation of heteroarenes
-
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
-
supporting information
p. 5901 - 5904
(2020/06/04)
-
- Carbazole based Electron Donor Acceptor (EDA) catalysis for the synthesis of biaryl and aryl-heteroaryl compounds
-
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
-
supporting information
p. 2510 - 2515
(2020/04/15)
-
- Access to Substituted Thiophenes through Xanthate-Mediated Vinyl C(sp2)-Br Bond Cleavage and Heterocyclization of Bromoenynes
-
An environmentally sustainable strategy for the chemoselective heterocyclization of bromoenynes through a transition-metal-free sulfuration/cyclization process is reported. Using inexpensive and safe EtOCS2K as a thiol surrogate and tetrabutylphosphonium bromide and H2O as a mixed solvent, the reaction provided a range of substituted thiophenes in moderate to good yields. In addition, 2,3,4,5-tetrasubstituted thiophenes were able to be prepared under mild reaction conditions by electrophilic heterocyclization with NH4I and EtOCS2K in good yields.
- Huang, Guoling,Li, Jian,Li, Jianrong,Li, Jiaming,Sun, Minghua,Zhou, Peng,Chen, Lu,Huang, Yubing,Jiang, Shaohua,Li, Yibiao
-
p. 13037 - 13049
(2020/11/26)
-
- Alternating Tetrafluorobenzene and Thiophene Units by Direct Arylation for Organic Electronics
-
Direct arylation represents an attractive alternative to the conventional cross-coupling methods because of its step-economic and eco-friendly advantages. A set of simple D–A oligomeric molecules (F-3, F-5, and F-7) by integrating thiophene (T) and tetraf
- Cui, Xiaoping,Xiao, Chengyi,Jiang, Wei,Wang, Zhaohui
-
supporting information
p. 1443 - 1447
(2019/04/04)
-
- C–H Arylation of N-Heteroarenes under Metal-Free Conditions and its Application towards the Synthesis of Pentabromo- and Pentachloropseudilins
-
Herein, we are reporting metal-free conditions for radical initiation and direct C–H arylation of N-heteroarenes. Starting from aniline, the corresponding arenediazonium salt generated in situ is reduced to an aryl radical in the presence of chloropromazine hydrochloride, a new reagent for this application. The optimized procedures are mild, operationally simple, and are working successfully with more diverse substrates in comparison to reported methods. The optimized method is also employed for the synthesis of marine natural products Pentabromo- and Pentachloropseudilins (PBP/PCP). In the present study, we also validated the potential of the Pentachloropseudilin (PCP), thus synthesized, for inhibition of Myosin1 function in mammalian cells and confirmed that PCP phenocopies Myosin1c depletion in cells.
- Kumar, Mukesh,Sharma, Shweta,Sil, Parijat,Kushwaha, Manoj,Mayor, Satyajit,Vishwakarma, Ram A.,Singh, Parvinder Pal
-
supporting information
p. 3591 - 3598
(2019/06/20)
-
- Ligand-Less Iron-Catalyzed Aromatic Cross-Coupling Difluoromethylation of Grignard Reagents with Difluoroiodomethane
-
Iron-catalyzed cross-coupling difluoromethylations of the Grignard reagents with difluoroiodomethane provide various aromatic difluoromethyl products in good yields, not employing sterically demanding ligands. Difluoromethylations proceed within 30 min at -20 °C with 2.0 equiv of the Grignard reagents and FeCl3 or Fe(acac)3 (2.5 mol %). Mechanistic investigations clarify difluoromethyl radical intervention; Fe(0) ate is initially generated. Single-electron transfer from Fe(0) ate to difluoroiodomethane takes place. Recombination with aryl groups gives Ar-CF2Hs. The catalyst can be regenerated by the Grignard reagents.
- Motohashi, Hirotaka,Kato, Miki,Mikami, Koichi
-
p. 6483 - 6490
(2019/05/16)
-
- Perylenequinonoid-catalyzed photoredox activation for the direct arylation of (het)arenes with sunlight
-
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
-
supporting information
p. 4364 - 4369
(2019/05/10)
-
- Phenalenyl Based Aluminum Compound for Catalytic C-H Arylation of Arene and Heteroarenes at Room Temperature
-
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.
-
p. 289 - 299
(2019/01/10)
-
- N,S-chelating triazole-thioether ligand for highly efficient palladium-catalyzed Suzuki reaction
-
1,2,3-Triazole-thioether compounds could serve as efficient ligands for Pd-catalyzed Suzuki reactions of various aryl iodides, bromides and chlorides. The reactions feature wide substrate scope and mild reaction conditions. Besides, shorter reaction time, lower catalyst loadings and quantitative yields with a turnover-frequency (TOF) value of up to 11,880 h?1 are other advantageous of this attractive protocol. The crystal structure analyses and computational studies revealed that the higher catalytic activity of the corresponding chelated palladium complex ascribed to the lower energy gap and the lower redox potential.
- Yan, Qiong,Zheng, Lei,Li, Miaomiao,Chen, Yunfeng
-
p. 101 - 105
(2019/07/19)
-
- C?I-Selective Cross-Coupling Enabled by a Cationic Palladium Trimer
-
While there is a growing interest in harnessing synergistic effects of more than one metal in catalysis, relatively little is known beyond bimetallic systems. This report describes the straightforward access to an air-stable Pd trimer and presents unambiguous reactivity data of its privileged capability to differentiate C?I over C?Br bonds in C?C bond formations (arylation and alkylation) of polyhalogenated arenes, which typical Pd0 and PdI-PdI catalysts fail to deliver. Experimental and computational reactivity data, including the first location of a transition state for bond activation by the trimer, are presented, supporting direct trimer reactivity to be feasible.
- Diehl, Claudia J.,Scattolin, Thomas,Englert, Ulli,Schoenebeck, Franziska
-
supporting information
p. 211 - 215
(2018/12/13)
-
- An Iron-Based Long-Lived Catalyst for Direct C?H Arylation of Arenes and Heteroarenes
-
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.
-
supporting information
p. 17651 - 17655
(2018/11/10)
-
- Gram-scale synthesis of aligned C3N4-polypyrrole heterojunction aerogels with tunable band structures as efficient visible and near infrared light-driven metal-free photocatalysts
-
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
-
p. 24920 - 24928
(2017/12/15)
-
- Visible-Light-Promoted Arylation Reactions Photocatalyzed by Bismuth(III) Oxide
-
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.
-
supporting information
p. 6986 - 6990
(2017/12/26)
-
- Porphyrin-Catalyzed Photochemical C–H Arylation of Heteroarenes
-
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
-
supporting information
p. 2104 - 2107
(2017/04/24)
-
- Carbocatalytic reductive coupling reactions: Via electron transfer from graphene to aryldiazonium salt
-
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
-
supporting information
p. 7226 - 7229
(2017/07/11)
-
- A g-C3N4/rGO nanocomposite as a highly efficient metal-free photocatalyst for direct C-H arylation under visible light irradiation
-
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
-
p. 46132 - 46138
(2017/10/10)
-
- Benzothiadiazole-Based Small-Molecule Semiconductors for Organic Thin-Film Transistors and Complementary-like Inverters
-
New benzothiadiazole derivatives, 4,7-bis(5-phenylthiophen-2-yl)benzo[c][1,2,5]thiadiazole (PT-BTD) and 4,7-bis[4-(thiophen-2-yl)phenyl]benzo[c][1,2,5]thiadiazole (TP-BTD), were synthesized and characterized as small-molecule organic semiconductors for organic thin-film transistors (OTFTs) and complementary inverters. The thermal, optical, and electrochemical properties of the new compounds were fully characterized. Vacuum-deposition and solution-shearing methods were used to fabricate thin films based on these compounds. Thin films based on PT-BTD exhibited p-channel characteristics with hole mobilities as high as 0.10 cm2 V?1 s?1 and current on/off ratios >107 for top-contact/bottom-gate OTFT devices. With an optimized blending ratio of PT-BTD and the representative n-channel semiconductor N,N′-1H,1H-perfluorobutyl dicyanoperylenediimide, bulk heterojunction ambipolar transistors were fabricated with balanced hole and electron mobilities of 0.10 and 0.07 cm2 V?1 s?1, respectively. Furthermore, a complementary-like inverter was fabricated using ambipolar thin-film transistors, which showed a high voltage gain of 84.
- Kim, Hyekyoung,Reddy, M. Rajeshkumar,Kim, Hyungsug,Choi, Donghee,Kim, Choongik,Seo, SungYong
-
p. 742 - 749
(2017/06/06)
-
- Interface coassembly of mesoporous MoS2 based-frameworks for enhanced near-infrared light driven photocatalysis
-
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
-
supporting information
p. 6431 - 6434
(2016/05/24)
-
- Novel organic semiconductors based on phenyl and phenylthienyl derivatives for organic thin-film transistors
-
New phenyl and phenylthienyl derivatives end-functionalized with carbazole and α-carboline, 9-(4- (9H-carbazol-9-yl)phenyl)-9H-carbazole, 9-(4-(9H-carbazol-9-yl)phenyl)-9H-pyrido[2,3-b]indole, 9- (3-(9H-carbazol-9-yl)phenyl)-9H-carbazole, 9-(3-(9H-carbazol-9-yl)phenyl)-9H-pyrido[2,3-b]indole, 9-(4-(5-(9H-carbazol-9-yl)thiophen-2-yl)phenyl)-9H-carbazole, and 9-(3-(5-(9H-carbazol-9-yl) thiophen-2-yl)phenyl)-9H-carbazole were synthesized and characterized as organic semiconductors for organic thin-film transistors (OTFTs). Most compounds exhibited p-channel characteristics with carrier mobility as high as 1.7 × 10-5 cm2/Vs and a current on/off ratio of 102-104 for top-contact/bottom-gate OTFT devices.
- Lee, Eunsoo,Thirupathaiah, Bodakuntla,Han, Jaeuk,Jung, Dahae,Kwon, Guhyun,Kim, Choongik,Seo, Sung Yong
-
p. 910 - 919
(2016/03/08)
-
- Light-Induced C-H Arylation of (Hetero)arenes by in Situ Generated Diazo Anhydrides
-
Diazo anhydrides (Ar-N=N-O-N=N-Ar) have been known since 1896 but have rarely been used in synthesis. This communication describes the development of a photochemical catalyst-free C-H arylation methodology for the preparation of bi(hetero)aryls by the one-pot reaction of anilines with tert-butyl nitrite and (hetero)arenes under neutral conditions. The key step in this procedure is the in situ formation and subsequent photochemical (>300 nm) homolytic cleavage of a transient diazo anhydride intermediate. The generated aryl radical then efficiently reacts with a (hetero)arene to form the desired bi(hetero)aryls producing only nitrogen, water, and tert-butanol as byproducts. The scope of the reaction for several substituted anilines and (hetero)arenes was investigated. A continuous-flow protocol increasing selectivity and safety has been developed enabling the experimentally straightforward preparation of a variety of substituted bi(hetero)aryls within 45 min of reaction time.
- Cantillo, David,Mateos, Carlos,Rincon, Juan A.,De Frutos, Oscar,Kappe, C. Oliver
-
supporting information
p. 12894 - 12898
(2015/09/07)
-
- Unexpected dual role of titanium dioxide in the visible light heterogeneous catalyzed C-H arylation of heteroarenes
-
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
-
p. 3900 - 3904
(2015/06/16)
-
- Flexible routes to thiophenes
-
Three convergent routes to thiophenes are described, hinging on the radical addition of α-xanthyl ketones to ethyl vinyl sulfide or to vinyl pivalate. The latter route ultimately proved to be the most versatile and efficient (61-94%).
- Jullien, Helene,Quiclet-Sire, Beatrice,Tetart, Thomas,Zard, Samir Z.
-
supporting information
p. 302 - 305
(2014/01/23)
-
- 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
-
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
-
p. 23377 - 23388
(2013/11/19)
-
- Sensitized photografting of diazonium salts by visible light.
-
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
-
-
- Iron-catalyzed oxidative coupling of arylboronic acids with benzene derivatives through homolytic aromatic substitution
-
Fe(OTf)3-1,10-phenanthroline catalyzes oxidative coupling of arylboronic acids with benzene derivatives using t-BuOOt-Bu as an oxidant. The reaction proceeds through homolytic aromatic substitution with aryl radicals generated from arylboronic acids and t-BuO.
- Uchiyama, Nanase,Shirakawa, Eiji,Nishikawa, Ryo,Hayashi, Tamio
-
supporting information; experimental part
p. 11671 - 11673
(2011/12/05)
-
- Synthesis of 3-(4-heteroaryl-phenyl)-8-oxabicyclo[3.2.1]octane-2-carboxylic acid methyl esters
-
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.
-
p. 599 - 603
(2007/10/03)
-
- Generation of aryl radicals from arylboronic acids by manganese(III) acetate: Synthesis of biaryls and heterobiaryls
-
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
-
p. 578 - 580
(2007/10/03)
-
- Synthesis and structure-activity relationships of 5-phenylthiophenecarboxylic acid derivatives as antirheumatic agents
-
5-(Phenylthiophene)-3-carboxylic acid (2a), a metabolite of esonarimod (1), which was developed as a new antirheumatic drug, was considered as a lead compound for new antirheumatic drugs. A new series of 2a derivatives were synthesized and their characteristic pharmacological effects, that is their antagonistic effect toward interleukin (IL)-1 in mice and the suppressive effect against adjuvant-induced arthritis (AIA) in rats, were evaluated and compared with those of 1. The structure-activity relationships indicated that [5-(4-bromophenyl)-thiophen-3-yl]acetic acid (5d), methyl [5-(4-chlorophenyl)-thiophen-3-yl]acetate (5h), and methyl [5-(4-bromophenyl)-thiophen-3-yl]acetate (5i) suppressed AIA more potently than 1 and all of the other synthesized compounds.
- Noguchi, Toshiya,Hasegawa, Masahiro,Tomisawa, Kazuyuki,Mitsukuchi, Morihiro
-
p. 4729 - 4742
(2007/10/03)
-
- Manganese(III) acetate-mediated oxidative coupling of phenylhydrazines with furan and thiophene: A novel method for hetero biaryl coupling
-
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
-
p. 8055 - 8058
(2007/10/03)
-
- Javelin-, hockey stick-, and boomerang-shaped liquid crystals. Structural variations on p-quinquephenyl
-
The ramifications of changing molecular geometry in a series of all-aromatic liquid crystals derived from p-quinquephenyl are reported. Substituting heterocyclic rings such as thiophene, oxadiazole, oxazole, or 1,3-phenylene into the p-quinquephenylene core affects molecular shape changes via the substituent's exocyclic bond angle. In general, we found that introducing nonlinearity into molecules depresses the melting transition temperature. The symmetric (boomerang-shaped) molecules, 2,5-bisbiphenyl-4-yl-1,3,4-oxadiazole, 2,5-bisbiphenyl-4-yl-oxazole, and 1,3-bisbiphenyl-4-yl-benzene, melt into isotropic phases showing small monotropic mesophases. By contrast, the asymmetric (hockey stick-shaped) mesogens, 2-terphenyl-4-yl-5-phenyl thiophene and 2-terphenyl-4-yl-5-phenyl-1,3,4-oxadiazole, exhibit more stable enantiotropic liquid crystalline phases. The hockey stick-shaped mesogens exhibit a smectic phase as well as a nematic phase. High-temperature X-ray determination of the smectic layer spacing gives an unambiguous picture of interdigitated, bilayerlike supramolecular architecture in the smectic phase. There are associated changes in the mesogen's electrostatic profile when a heterocycle is introduced into the quinquiphenylene framework (e.g., conjugation is perturbed). Our findings suggest that steric packing considerations dominate the phase preferences (nematic versus smectic phases). However, electronic considerations (conjugation) appear to control the range of mesomorphism in this new family of nonlinear liquid crystals.
- Dingemans, Theo J.,Murthy, N. Sanjeeva,Samulski, Edward T.
-
p. 8845 - 8860
(2007/10/03)
-
- Synthesis of thiophene/phenylene co-oligomers. II [1]. Block and alternating co-oligomers
-
We report the synthesis of block and alternating thiophene/phenylene co- oligomers that is based either on the Suzuki coupling reaction or on the Grignard reaction. These reaction schemes enable us to obtain the target compounds at reasonably high yields.
- Hotta,Kimura,Lee,Tamaki
-
p. 281 - 286
(2007/10/03)
-
- Phase-Transfer-Catalyzed Gomberg-Bachmann Synthesis of Unsymmetrical Biarenes: A Survey of Catalysts and Substrates
-
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.
-
p. 1594 - 1603
(2007/10/02)
-