- 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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- UiO-66 microcrystals catalyzed direct arylation of enol acetates and heteroarenes with aryl diazonium salts in water
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UiO-66 is a classic Metal–organic framework (MOF) that constructed by zirconium cations and terephthalate with high chemical and thermal stability. Using pristine UiO-66 nanocrystals as the catalysts, the carbon–carbon bond formation based on denitrogenat
- Sun, Zhong-Hua,Chen, Wang,Qian, Bing-Bing,Wang, Liang,Yu, Binxun,Chen, Qun,He, Ming-Yang,Zhang, Zhi-Hui
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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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- C-H arylation reactions through aniline activation catalysed by a PANI-g-C3N4-TiO2 composite under visible light in aqueous medium
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A PANI (polyaniline)-g-C3N4-TiO2 composite was prepared and found to be efficient for radical C-H arylation reactions. The arylation process involved coupling of in situ generated aryl diazonium salts from aniline with heteroarenes, enol acetates or benzoquinones under visible light in aqueous medium or pure water. A broad range of substrates survived the reaction conditions to provide the desired products in moderate to good yields. Scale-up (10 mmol) synthesis was also achieved. This semiconductor photocatalyst showed good photocatalytic performance and stability. Recycle studies showed that this composite could be readily recovered and a slight decrease in the catalytic activity was observed after ten consecutive runs.
- Wang, Liang,Shen, Jun,Yang, Sen,Liu, Wenjie,Chen, Qun,He, Mingyang
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supporting information
p. 1290 - 1296
(2018/03/26)
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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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- 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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supporting information
p. 325 - 333
(2018/01/15)
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- One-Pot Preparation of Stable Organoboronate Reagents for the Functionalization of Unsaturated Four- and Five-Membered Carbo and Heterocycles
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Combining a facile preparation of organoboronates with their remarkable stability and functional group tolerance allows for the straightforward synthesis of four- and five-membered carbo- and heterocycles. While most strategies rely on the ex situ preparation of boronic acids as isolated intermediates, we demonstrate that in situ transmetalation of sensitive organometallics with boron alkoxides can lead to great stabilization of such species at room temperature. A considerable extension of the library of unsaturated strained structures is achieved through these sequences, expanding the potential applicability of such unusual building blocks.
- Baumann, Andreas N.,Eisold, Michael,Music, Arif,Didier, Dorian
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p. 3149 - 3160
(2018/05/28)
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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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- An Active Palladium Colloidal Catalyst for the Selective Oxidative Heterocoupling of (Hetero)Aryl Boronic Acids
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A highly selective oxidative heterocoupling protocol for (hetero)aryl boronic acids with an active palladium colloidal catalyst was developed. The judicious choice of electronically different aryl boronic acids made possible such couplings under mild conditions, with air as oxidant, while embracing a wide substrate scope. This successful approach further allowed the development of a unique one-pot sequential oxidative heterocoupling/Suzuki–Miyaura cross-coupling tandem process for accessing substituted terphenyls.
- Sable, Vaibhav,Maindan, Karan,Bhilare, Shatrughn,Chrysochos, Nicolas,Schulzke, Carola,Kapdi, Anant R.
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supporting information
p. 2489 - 2498
(2018/09/10)
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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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- Radical C-H arylations of (hetero)arenes catalysed by gallic acid
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Gallic acid efficiently catalyses radical arylations in water-acetone at room temperature. This methodology proved to be versatile and scalable. Therefore, it constitutes a greener alternative to arylation. Moreover, considering that gallic acid is an abundant vegetable tannin, this work also unleashes an alternative method for the reutilisation of bio-wastes.
- Perretti, Marcelle D.,Monzón, Diego M.,Crisóstomo, Fernando P.,Martín, Víctor S.,Carrillo, Romen
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supporting information
p. 9036 - 9039
(2016/07/21)
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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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- Development of a new physicochemical model for brain penetration and its application to the design of centrally acting H2 receptor histamine antagonists
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A rational approach to the design of centrally acting agents is presented, based initially upon a comparison of the physicochemical properties of three typical histamine H2 receptor antagonists which do not readily cross the blood-brain barrier with those of the three brain-penetrating drugs clonidine (6), mepyramine (7), and imipramine (8). A good correlation was found between the logarithms of the equilibrium brain/blood concentration ratios in the rat and the partition parameter, Δ log P, defined as log P (1-octanol/water) - log P (cyclohexane/water), which suggests that brain penetration might be improved by reducing overall hydrogen-bonding ability. This model has been employed as a guide in the design of novel brain-penetrating H2 antagonists by the systematic structural modification of representatives of different structural types of H2 antagonists. Although marked increases in brain penetration amongst congeners of cimetidine (1), ranitidine (9), and tiotidine (10) were achieved, no compound was found with an acceptable combination of H2 antagonist activity (-log K(B) in the guinea pig atrium > 7.0) and brain penetration (steady-state brain/blood concentration ratio > 1.0). Conversely, structural modification of N-[[(piperidinylmethyl)phenoxy]propyl]acetamide (30) led to several potent, novel compounds which readily cross the blood-brain barrier. One of these, zolantidine (SK&F 95282, 41), whose -log K(B) is 7.46 and steady-state brain/blood ratio is 1.4, has been identified for use in studying histaminergic H2 receptor mechanisms in brain. Comparison of Δ log P values with the logarithms of the brain/blood ratios for 20 structurally diverse compounds for which data became available confirms a highly significant correlation and supports the general validity of this model.
- Young,Mitchell,Brown,Ganellin,Griffiths,Jones,Rana,Saunders,Smith,Sore,Wilks
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p. 656 - 671
(2007/10/02)
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