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Artículos de revistas sobre el tema "Photoredox catalytic system"

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Publicado: 25 de mayo de 2024

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1

Yang, Qiong, Fengqian Zhao, Na Zhang, Mingke Liu, Huanhuan Hu, Jingjie Zhang y Shaolin Zhou. "Mild dynamic kinetic resolution of amines by coupled visible-light photoredox and enzyme catalysis". Chemical Communications 54, n.º 100 (2018): 14065–68. http://dx.doi.org/10.1039/c8cc07990k.

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A mild and efficient dynamic kinetic resolution (DKR) of amines was achieved by combining visible-light-induced photoredox catalysis and enzyme catalysis. This dual catalytic system was appropriate for both monoamines and 1,4-diamines.
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2

Leadbeater, Nicholas, Jyoti Nandi y Mason Witko. "Combining Oxoammonium Cation Mediated Oxidation and Photoredox Catalysis for the Conversion of Aldehydes into Nitriles". Synlett 29, n.º 16 (12 de septiembre de 2018): 2185–90. http://dx.doi.org/10.1055/s-0037-1610272.

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A method to oxidize aromatic aldehydes to nitriles has been developed. It involves a dual catalytic system of 4-acetamido-TEMPO and visible-light photoredox catalysis. The reaction is performed using ammonium persulfate as both the terminal oxidant and nitrogen source.
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3

Tlahuext-Aca, Adrian, Matthew N. Hopkinson, Basudev Sahoo y Frank Glorius. "Dual gold/photoredox-catalyzed C(sp)–H arylation of terminal alkynes with diazonium salts". Chemical Science 7, n.º 1 (2016): 89–93. http://dx.doi.org/10.1039/c5sc02583d.

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4

Hu, Xia, Guoting Zhang, Faxiang Bu, Xu Luo, Kebing Yi, Heng Zhang y Aiwen Lei. "Photoinduced oxidative activation of electron-rich arenes: alkenylation with H2 evolution under external oxidant-free conditions". Chemical Science 9, n.º 6 (2018): 1521–26. http://dx.doi.org/10.1039/c7sc04634k.

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5

Hossain, Asik, Aditya Bhattacharyya y Oliver Reiser. "Copper’s rapid ascent in visible-light photoredox catalysis". Science 364, n.º 6439 (2 de mayo de 2019): eaav9713. http://dx.doi.org/10.1126/science.aav9713.

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Visible-light photoredox catalysis offers a distinct activation mode complementary to thermal transition metal catalyzed reactions. The vast majority of photoredox processes capitalizes on precious metal ruthenium(II) or iridium(III) complexes that serve as single-electron reductants or oxidants in their photoexcited states. As a low-cost alternative, organic dyes are also frequently used but in general suffer from lower photostability. Copper-based photocatalysts are rapidly emerging, offering not only economic and ecological advantages but also otherwise inaccessible inner-sphere mechanisms, which have been successfully applied to challenging transformations. Moreover, the combination of conventional photocatalysts with copper(I) or copper(II) salts has emerged as an efficient dual catalytic system for cross-coupling reactions.
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6

Naumann, Robert, Christoph Kerzig y Martin Goez. "Laboratory-scale photoredox catalysis using hydrated electrons sustainably generated with a single green laser". Chem. Sci. 8, n.º 11 (2017): 7510–20. http://dx.doi.org/10.1039/c7sc03514d.

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A combined photokinetical approach helped develop and optimize a green-light driven photoredox catalytic system that generates a “super-reductant” with simple instrumentation, consumes only a bioavailable donor, and provides very high turnover numbers.
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7

Pagire, Santosh K., Naoya Kumagai y Masakatsu Shibasaki. "Introduction of a 7-aza-6-MeO-indoline auxiliary in Lewis-acid/photoredox cooperative catalysis: highly enantioselective aminomethylation of α,β-unsaturated amides". Chemical Science 11, n.º 20 (2020): 5168–74. http://dx.doi.org/10.1039/d0sc01890b.

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An efficient cooperative chiral Lewis acid and photoredox catalytic system towards the highly enantioselective radical conjugate addition of α-amino radicals to α,β-unsaturated amides is developed with the implementation of unique auxiliaries.
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8

Kostromitin, Vladislav S., Vitalij V. Levin y Alexander D. Dilman. "Atom Transfer Radical Addition via Dual Photoredox/Manganese Catalytic System". Catalysts 13, n.º 7 (19 de julio de 2023): 1126. http://dx.doi.org/10.3390/catal13071126.

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Atom transfer radical addition of bromonitromethane and 1,2-dibromotetrafluoroethane to alkenes is described. The reaction is performed under blue light irradiation using two catalysts: 4CzIPN and manganese (II) bromide. The cyanoarene photocatalyst serves for the redox activation of starting organic bromide, while the manganese salt facilitates the trapping of the alkyl radical with the formation of the carbon–bromine bond.
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9

Li, Heng-Hui, Shaoyu Li, Jun Kee Cheng, Shao-Hua Xiang y Bin Tan. "Direct arylation of N-heterocycles enabled by photoredox catalysis". Chemical Communications 58, n.º 27 (2022): 4392–95. http://dx.doi.org/10.1039/d2cc01212j.

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A photoredox catalytic system was developed to construct N-heterobiaryls via direct arylation from readily accessible substrates. While phenols act as both coupling partner and proton donor, regular arenes were also applicable with HFIP as a solvent.
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10

Mitsunuma, Harunobu, Hiromu Fuse, Yu Irie, Masaaki Fuki, Yasuhiro Kobori, Kosaku Kato, Akira Yamakata, Masahiro Higashi y Motomu Kanai. "(Invited) Identification of a Self-Photosensitizing Hydrogen Atom Transfer Organocatalyst System". ECS Meeting Abstracts MA2023-01, n.º 14 (28 de agosto de 2023): 1355. http://dx.doi.org/10.1149/ma2023-01141355mtgabs.

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The carbon-hydrogen (C-H) bond is a fundamental chemical bond that constitutes organic molecules, and its direct conversion leads to highly efficient molecular synthesis. In recent years, the hydrogen atom transfer (HAT) catalysis using the energy of visible light, has been attracting attention. However, existing methods require the use of photoredox catalysts such as organic molecules with complex structures and expensive metal complexes. In this study, we developed an organocatalytic system that mimics the electron transfer process of enzymes in vivo and promotes functionalization of stable C-H bond without photoredox catalyst. We designed a thiophosphoric acid catalyst that contains both a redox-active binaphthyl moiety and a sulfur atom. We found that this catalyst forms charge-transfer complexes with electron-deficient heteroaromatics and catalytically produces thyil radical via multi-step electron transfer under visible light irradiation. Based on the above design, we decided to investigate the formation of active HAT catalytic species in the absence of photoredox catalysis by the Minisci-type reaction using aldehydes and N-heteroaromatic rings. The results of the study confirmed that 29% of the product was obtained when using binaphtyl thiophosphoric acid (TPA) catalyst, as expected. Yield improved to 80% when an electron-donating group was introduced to the binaphthyl skeleton to enhance the donor-acceptor interaction. Changing the binaphthyl skeleton and thiophosphoric acid moieties markedly reduced reactivity, indicating that the presence of a sulfur atom in addition to a rigid binaphthyl skeleton is essential for the efficient reaction progress. With this optimized condition, alkylation of N-heteroaromatic rings by C-H bond activation of alcohols was found to proceed. Dehydrogenation of alcohols and benzylation of imines were also successfully achieved by using N-heteroaromatic catalyst. The mechanism of the electron transfer process has been confirmed by spectroscopic and computational methods, and will be presented in detail in the lecture. Figure 1
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11

Zhou, Zhao-Zhao, Rui-Qiang Jiao, Ke Yang, Xi-Meng Chen y Yong-Min Liang. "Photoredox/palladium co-catalyzed propargylic benzylation with internal propargylic carbonates". Chemical Communications 56, n.º 85 (2020): 12957–60. http://dx.doi.org/10.1039/d0cc04986g.

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The developed photo/palladium dual catalytic system provided a novel route to internal propargylic benzylation products. A radical coupling mechanism between the propargylic radical and benzyl radical was proposed.
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12

Pratt, Cameron J., R. Adam Aycock, Max D. King y Nathan T. Jui. "Radical α-C–H Cyclobutylation of Aniline Derivatives". Synlett 31, n.º 01 (3 de septiembre de 2019): 51–54. http://dx.doi.org/10.1055/s-0039-1690197.

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A catalytic system has been developed for the direct alkylation of α-C–H bonds of aniline derivatives with strained C–C σ-bonds. This method operates through a photoredox mechanism in which oxidative formation of aminoalkyl radical intermediates enables addition to a bicyclobutane derivative, giving rise to α-cyclobutyl N-alkylaniline products. This mild system proceeds through a redox- and proton-neutral mechanism and is operational for a range of substituted arylamine derivatives.
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13

Koohgard, Mehdi, Haniehsadat Karimitabar y Mona Hosseini-Sarvari. "Visible-light-mediated semi-heterogeneous black TiO2/nickel dual catalytic C (sp2)–P bond formation toward aryl phosphonates". Dalton Transactions 49, n.º 47 (2020): 17147–51. http://dx.doi.org/10.1039/d0dt03507f.

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The combination of black TiO2 nanoparticles (NPs) with a nickel catalyst provides a low-cost, sustainable, and reusable alternative photoredox/nickel system to a homogeneous counterpart (noble metals) in C(sp2)−P coupling reaction.
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14

Wilger, Dale J., Nathan J. Gesmundo y David A. Nicewicz. "Catalytic hydrotrifluoromethylation of styrenes and unactivated aliphatic alkenes via an organic photoredox system". Chemical Science 4, n.º 8 (2013): 3160. http://dx.doi.org/10.1039/c3sc51209f.

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15

Guillemard, Lucas y Joanna Wencel-Delord. "When metal-catalyzed C–H functionalization meets visible-light photocatalysis". Beilstein Journal of Organic Chemistry 16 (21 de julio de 2020): 1754–804. http://dx.doi.org/10.3762/bjoc.16.147.

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While aiming at sustainable organic synthesis, over the last decade particular attention has been focused on two modern fields, C–H bond activation, and visible-light-induced photocatalysis. Couplings through C–H bond activation involve the use of non-prefunctionalized substrates that are directly converted into more complex molecules, without the need of a previous functionalization, thus considerably reduce waste generation and a number of synthetic steps. In parallel, transformations involving photoredox catalysis promote radical reactions in the absence of radical initiators. They are conducted under particularly mild conditions while using the visible light as a cheap and economic energy source. In this way, these strategies follow the requirements of environment-friendly chemistry. Regarding intrinsic advantages as well as the complementary mode of action of the two catalytic transformations previously introduced, their merging in a synergistic dual catalytic system is extremely appealing. In that perspective, the scope of this review aims to present innovative reactions combining C–H activation and visible-light induced photocatalysis.
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16

Claros, Miguel, Alicia Casitas y Julio Lloret-Fillol. "Visible-Light Reductive Cyclization of Nonactivated Alkyl Chlorides". Synlett 30, n.º 13 (17 de julio de 2019): 1496–507. http://dx.doi.org/10.1055/s-0037-1611878.

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Nonactivated alkyl chlorides are readily available and bench-stable feedstocks; however, they exhibit an inherent chemical inertness, in part, due to their large negative reduction potentials, which have precluded their widespread use as radical precursors in visible-light photocatalysis. Herein, we highlight some recent strategies for activating challenging organic halides under light irradiation, with special emphasis in C(sp3)–halide bonds. In this line, a brief summary of the reactivity of Vitamin B12, F430 cofactor and derivatives is required to comprehend the chemistry behind our developed Cu/M (M = Co, Ni) dual catalytic system. Catalyst design has been key for developing a mild and general photoredox methodology for the intramolecular reductive cyclization of nonactivated alkyl chlorides with tethered alkenes. The cleavage of strong C(sp3)–Cl bonds is mediated by a highly nucleophilic low-valent cobalt or nickel intermediate generated by visible-light photoredox reduction employing a copper photosensitizer.
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17

Thullen, Scott M. y Tomislav Rovis. "A Mild Hydroaminoalkylation of Conjugated Dienes Using a Unified Cobalt and Photoredox Catalytic System". Journal of the American Chemical Society 139, n.º 43 (19 de octubre de 2017): 15504–8. http://dx.doi.org/10.1021/jacs.7b09252.

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18

Zhang, Hong-Hao, Jia-Jia Zhao y Shouyun Yu. "Enantioselective α-Allylation of Anilines Enabled by a Combined Palladium and Photoredox Catalytic System". ACS Catalysis 10, n.º 8 (24 de marzo de 2020): 4710–16. http://dx.doi.org/10.1021/acscatal.0c00871.

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19

Zheng, Jun y Bernhard Breit. "Regiodivergent Hydroaminoalkylation of Alkynes and Allenes by a Combined Rhodium and Photoredox Catalytic System". Angewandte Chemie 131, n.º 11 (29 de enero de 2019): 3430–35. http://dx.doi.org/10.1002/ange.201813646.

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20

Zheng, Jun y Bernhard Breit. "Regiodivergent Hydroaminoalkylation of Alkynes and Allenes by a Combined Rhodium and Photoredox Catalytic System". Angewandte Chemie International Edition 58, n.º 11 (29 de enero de 2019): 3392–97. http://dx.doi.org/10.1002/anie.201813646.

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21

Kostromitin, Vladislav S., Artem A. Zemtsov, Vladimir A. Kokorekin, Vitalij V. Levin y Alexander D. Dilman. "Atom-transfer radical addition of fluoroalkyl bromides to alkenes via a photoredox/copper catalytic system". Chemical Communications 57, n.º 42 (2021): 5219–22. http://dx.doi.org/10.1039/d1cc01609a.

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22

Wilger, Dale J., Nathan J. Gesmundo y David A. Nicewicz. "ChemInform Abstract: Catalytic Hydrotrifluoromethylation of Styrenes and Unactivated Aliphatic Alkenes via an Organic Photoredox System." ChemInform 44, n.º 49 (14 de noviembre de 2013): no. http://dx.doi.org/10.1002/chin.201349046.

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23

Ma, Wenchao, Dong Chen, Yuhong Ma, Li Wang, Changwen Zhao y Wantai Yang. "Visible-light induced controlled radical polymerization of methacrylates with Cu(dap)2Cl as a photoredox catalyst". Polymer Chemistry 7, n.º 25 (2016): 4226–36. http://dx.doi.org/10.1039/c6py00687f.

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Under visible light irradiation, block copolymers of PPEGMA-b-PMMA with high molecular weights and narrow molecular weight distributions are obtained starting from a PPEGMA macroinitiator in the presence of the Cu(dap)2Cl/Me6TREN catalytic system.
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24

Lopat’eva, Elena R., Igor B. Krylov y Alexander O. Terent’ev. "t-BuOOH/TiO2 Photocatalytic System as a Convenient Peroxyl Radical Source at Room Temperature under Visible Light and Its Application for the CH-Peroxidation of Barbituric Acids". Catalysts 13, n.º 9 (19 de septiembre de 2023): 1306. http://dx.doi.org/10.3390/catal13091306.

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TiO2 is one of the most promising heterogeneous photoredox catalysts employed in oxidative pollutant destruction, CO2 reduction, water splitting, disinfection, solar cell design and organic synthesis. Due to the wide bandgap of TiO2, visible light energy is not sufficient for its activation, and electron/hole pairs generated upon UV irradiation demonstrate limited selectivity for application in organic synthesis. Thus, the development of TiO2-based catalytic systems activated by visible light is highly attractive. In the present work we demonstrate the generation of t-BuOO• radicals from tert-butylhydroperoxide catalyzed using commercially available unmodified TiO2 under visible light. This finding was used for the highly selective CH-peroxidation of barbituric acids, which contrasts with the behavior of the known TiO2/H2O2/UV photocatalytic system used for deep oxidation of organic pollutants.
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25

Ghosh, Indrajit, Jagadish Khamrai, Aleksandr Savateev, Nikita Shlapakov, Markus Antonietti y Burkhard König. "Organic semiconductor photocatalyst can bifunctionalize arenes and heteroarenes". Science 365, n.º 6451 (25 de julio de 2019): 360–66. http://dx.doi.org/10.1126/science.aaw3254.

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Photoexcited electron-hole pairs on a semiconductor surface can engage in redox reactions with two different substrates. Similar to conventional electrosynthesis, the primary redox intermediates afford only separate oxidized and reduced products or, more rarely, combine to one addition product. Here, we report that a stable organic semiconductor material, mesoporous graphitic carbon nitride (mpg-CN), can act as a visible-light photoredox catalyst to orchestrate oxidative and reductive interfacial electron transfers to two different substrates in a two- or three-component system for direct twofold carbon–hydrogen functionalization of arenes and heteroarenes. The mpg-CN catalyst tolerates reactive radicals and strong nucleophiles, is straightforwardly recoverable by simple centrifugation of reaction mixtures, and is reusable for at least four catalytic transformations with conserved activity.
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26

Guerrero, Isabel, Clara Viñas, Francesc Teixidor y Isabel Romero. "Unveiling Non-Covalent Interactions in Novel Cooperative Photoredox Systems for Efficient Alkene Oxidation in Water". Molecules 29, n.º 10 (18 de mayo de 2024): 2378. http://dx.doi.org/10.3390/molecules29102378.

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A new cooperative photoredox catalytic system, [RuII(trpy)(bpy)(H2O)][3,3′-Co(8,9,12-Cl3-1,2-C2B9H8)2]2, 5, has been synthesized and fully characterized for the first time. In this system, the photoredox catalyst [3,3′-Co(8,9,12-Cl3-1,2-C2B9H8)2]− [Cl6-1]−, a metallacarborane, and the oxidation catalyst [RuII(trpy)(bpy)(H2O)]2+, 2 are linked by non-covalent interactions. This compound, along with the one previously synthesized by us, [RuII(trpy)(bpy)(H2O)][(3,3′-Co(1,2-C2B9H11)2]2, 4, are the only examples of cooperative molecular photocatalysts in which the catalyst and photosensitizer are not linked by covalent bonds. Both cooperative systems have proven to be efficient photocatalysts for the oxidation of alkenes in water through Proton Coupled Electron Transfer processes (PCETs). Using 0.05 mol% of catalyst 4, total conversion values were achieved after 15 min with moderate selectivity for the corresponding epoxides, which decreases with reaction time, along with the TON values. However, with 0.005 mol% of catalyst, the conversion values are lower, but the selectivity and TON values are higher. This occurs simultaneously with an increase in the amount of the corresponding diol for most of the substrates studied. Photocatalyst 4 acts as a photocatalyst in both the epoxidation of alkenes and their hydroxylation in aqueous medium. The hybrid system 5 shows generally higher conversion values at low loads compared to those obtained with 4 for most of the substrates studied. However, the selectivity values for the corresponding epoxides are lower even after 15 min of reaction. This is likely due to the enhanced oxidizing capacity of CoIV in catalyst 5, resulting from the presence of more electron-withdrawing substituents on the metallacarborane platform.
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27

Rouch, William D., Miao Zhang y Ryan D. McCulla. "Conjugated polymers as photoredox catalysts: a new catalytic system using visible light to promote aryl aldehyde pinacol couplings". Tetrahedron Letters 53, n.º 37 (septiembre de 2012): 4942–45. http://dx.doi.org/10.1016/j.tetlet.2012.06.144.

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28

Rostoll-Berenguer, Jaume, Gonzalo Blay, José Pedro y Carlos Vila. "9,10-Phenanthrenedione as Visible-Light Photoredox Catalyst: A Green Methodology for the Functionalization of 3,4-Dihydro-1,4-Benzoxazin-2-Ones through a Friedel-Crafts Reaction". Catalysts 8, n.º 12 (12 de diciembre de 2018): 653. http://dx.doi.org/10.3390/catal8120653.

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A visible-light photoredox functionalization of 3,4-dihydro-1,4-benzoxazin-2-ones through a Friedel-Crafts reaction with indoles using an inexpensive organophotoredox catalyst is described. The reaction uses a dual catalytic system that is formed by a photocatalyst simple and cheap, 9,10-phenanthrenedione, and a Lewis acid, Zn(OTf)2. 5W white LEDs are used as visible-light source and oxygen from air as a terminal oxidant, obtaining the corresponding products with good yields. The reaction can be extended to other electron-rich arenes. Our methodology represents one of the most valuable and sustainable approach for the functionalization of 3,4-dihydro-1,4-benzoxazin-2-ones, as compared to the reported procedures. Furthermore, several transformations were carried out, such as the synthesis of the natural product cephalandole A and a tryptophol derivative.
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29

Mitsunuma, Harunobu, Xue Peng, Yuki Hirao, Shunsuke Yabu, Hirofumi Sato, Masahiro Higashi y Motomu Kanai. "(Invited) Titanium-Catalyzed Intermolecular Radical Addition to Ketones Via Sp 3 C-H Bond Activation". ECS Meeting Abstracts MA2022-01, n.º 13 (7 de julio de 2022): 914. http://dx.doi.org/10.1149/ma2022-0113914mtgabs.

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Tertiary alcohols are widely present in natural products, pharmaceuticals, and agrochemicals. Radical addition reaction to ketones is a simple and waste-free synthetic method for preparation of tertiary alcohols with high functional group tolerance. Therefore, direct radical addition reactions to ketones can be applied to a wider range of substrates. However, radical addition to carbonyl groups is a thermodynamically unfavored process, especially in the case of intermolecular radical addition to ketones, where the resulting alkoxy radical can easily undergo β-fragmentation to yield the starting material. For successful radical addition, therefore, the alkoxy radical must be trapped by a proper trapping reagent. In this study, we have found that a ternary hybrid catalytic system consisting of acridinium photoredox catalyst, thiophosphoric imide (TPI) catalyst, and titanium complex catalyst can promote intermolecular addition reactions of various ketones with organic molecules by activation of sp3 C-H bonds. The thiyl radicals generated by the excited photoredox-catalyzed one-electron oxidation of TPI extracted hydrogen atoms from organic molecules such as toluene, benzyl alcohol, alkenes, aldehydes, and THF. The carbon-centered radical species thus generated are added to various ketones and aldehydes. This method can be applied to the first direct reaction to aliphatic ketones using a variety of hydrocarbon feedstocks. The unfavorable bond-forming step was facilitated by the simultaneous one-electron reduction of the intermediate alkoxy radical by catalytically generated titanium(III) species. This reaction provided an efficient and simple approach to tertiary alcohols and was successfully applied in the late-stage functionalization of drugs and their derivatives. The proposed mechanism was supported by both experimental and theoretical studies. Figure 1
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30

Nagao, Kazunori y Hirohisa Ohmiya. "(Invited, Digital Presentation) Carbocation Generation By Organophotoredox Catalyzed Radical-Polar Crossover". ECS Meeting Abstracts MA2022-01, n.º 13 (7 de julio de 2022): 913. http://dx.doi.org/10.1149/ma2022-0113913mtgabs.

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Carbocation is one of the most common and reactive chemical species in organic chemistry, which has been broadly utilized for alkylation of various nucleophiles and rearrangement reaction. Conventionally, carbocation is generated from alkyl electrophiles or alkenes in the presence of strong Lewis acids and Brønsted acids, which narrows usable nucleophiles and coexistable functional groups. The requirement of strong acidic conditions would originate from the difficulty of two electron abstraction from carbocation precursors at once. Recently, to solve this problem, activation of substrates via single electron transfer was presented. Knowles and co-workers reported the carbocation generation from the mesolytic cleavage of alkoxyamine-derived radical cation, that is generated by a visible-light mediated photoredox catalysis. Although this protocol does not require the strong acids, the low accessibility of alkoxyamine substrates restricted the introducible alkyl groups. In this presentation, a new approach to catalytic generation of carbocation by a visible light-mediated organophotoredox catalysis is provided. We were interested in an organocatalysis merging with the radical-polar crossover (RPC) mechanism as an approach to non-acidic and catalytic generation of carbocations. Details of our scenario for the RPC are described in Figure. We selected N-Ph-benzo[b]phenothiazine (PTH) as a suitable organophotoredox RPC catalyst due to three features: excitation in the UV-visible area, high reduction potential and potential persistent properties of the corresponding radical cation. Aliphatic carboxylic acid-derived redox active esters were chosen as carbocation precursors due to the availability and the well-studied reactivity. The catalytic system is initiated by single electron transfer from a phenothiazine catalyst to a redox active ester under irradiation of a blue light-emitting diode (LED) to generate the radical cation form of the catalyst (A) and an alkyl radical (B). Then, recombination process between A and B affords an alkylsulfonium intermediate C, which acts as a carbocation equivalent. The carbocation equivalent was applied to alkylation of various nucleophiles and the semipinacol rearrangement reactions. First, the catalytic system was exploited to alkylation of various nucleophiles. After screening of reaction conditions, the combination of N-phenyl benzo[b]phenothiazine and lithium tetrafluoroborate was found to be effective in this alkylation protocol. Aliphatic alcohol, water, amide, thiol, fluoride anion and allylsilane could participate in this organophotoredox catalysis as nucleophiles. This protocol allowed to use secondary or tertiary aliphatic carboxylic acid-derived redox active esters as alkylating reagents, providing sterically hindered molecules with functional group compatibility. Subsequently, we applied the photochemically-generated carbocation equivalent to the semipinacol rearrangement reaction. Although the semipinacol rearrangement reaction has been utilized in key steps for construction of complex carbon frameworks in total synthesis of natural products, the conventional methods require specific design of the substrates and harsh reaction conditions to control the reactivity and regioselectivity. Since our method has the advantage of using carboxylic acids as the carbocation precursors, the substrates are easily synthesized from the corresponding enolate species derived from aliphatic carboxylic acids and carbonyl compounds. Then, we found the b-hydroxy redox active ester derivatives underwent the decarboxylative semipinacol rearrangement reaction, affording the complex carbonyl compounds. For example, the reaction with substrate prepared from aromatic aldehyde and secondary aliphatic carboxylic acid proceeded to give the aldehyde bearing an a-quaternary carbon center through migration of the aromatic ring. The reactions with cyclic ketone-derived substrates also occurred to furnish the ring expansion products. Figure 1
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31

Liang, Zhi-Yu, Jin-Xin Wei, Xiu Wang, Yan Yu y Fang-Xing Xiao. "Elegant Z-scheme-dictated g-C3N4 enwrapped WO3 superstructures: a multifarious platform for versatile photoredox catalysis". Journal of Materials Chemistry A 5, n.º 30 (2017): 15601–12. http://dx.doi.org/10.1039/c7ta04333c.

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Robust photoredox systems have been rationally designed and crafted based on in situ self-assembled g-C3N4/WO3 superstructures which demonstrated versatile photoredox catalytic performances under visible light irradiation.
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32

Su, Xiaoxue, Fan Yang, Yusheng Wu y Yangjie Wu. "Direct C4–H phosphonation of 8-hydroxyquinoline derivatives employing photoredox catalysis and silver catalysis". Organic & Biomolecular Chemistry 16, n.º 15 (2018): 2753–56. http://dx.doi.org/10.1039/c8ob00370j.

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33

Ionova, Violetta, Anton Abel, Alexei Averin y Irina Beletskaya. "Heterobinuclear Metallocomplexes as Photocatalysts in Organic Synthesis". Catalysts 13, n.º 4 (18 de abril de 2023): 768. http://dx.doi.org/10.3390/catal13040768.

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Photocatalytic processes under visible light have constantly been finding more and more applications in organic synthesis as they allow a wide range of transformations to proceed under mild conditions. The combination of photoredox catalysis with metal complex catalysis gives an opportunity to employ the advantages of these two methodologies. Covalent bonding of photocatalyst and metal complex catalyst using bridging ligands increases the efficiency of the electron and energy transfer between these two parts of the catalyst, leading to more efficient and selective catalytic systems. Up to now, after numerous investigations of the photocatalytic reduction of CO2 and hydrogen generation, such a strategy was firmly established to substantially increase the catalyst’s activity. This review is aimed at the achievements and perspectives in the field of design and application of heterobinuclear metal complexes as photocatalysts in organic synthesis.
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34

Xu, Zhaoliang, Yu Hu, Lei Wang, Mingli Sun y Pinhua Li. "Merging cobalt and photoredox catalysis for the C8–H alkoxylation of 1-naphthylamine derivatives with alcohols". Organic & Biomolecular Chemistry 19, n.º 46 (2021): 10112–19. http://dx.doi.org/10.1039/d1ob01721g.

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35

Li, Mingle, Kalayou Hiluf Gebremedhin, Dandan Ma, Zhongji Pu, Tao Xiong, Yunjie Xu, Jong Seung Kim y Xiaojun Peng. "Conditionally Activatable Photoredox Catalysis in Living Systems". Journal of the American Chemical Society 144, n.º 1 (28 de diciembre de 2021): 163–73. http://dx.doi.org/10.1021/jacs.1c07372.

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36

Petersen, Wade F., Richard J. K. Taylor y James R. Donald. "Photoredox-catalyzed procedure for carbamoyl radical generation: 3,4-dihydroquinolin-2-one and quinolin-2-one synthesis". Organic & Biomolecular Chemistry 15, n.º 27 (2017): 5831–45. http://dx.doi.org/10.1039/c7ob01274h.

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37

Hu, Qiushi, Xuemeng Yu, Shaokuan Gong y Xihan Chen. "Nanomaterial catalysts for organic photoredox catalysis-mechanistic perspective". Nanoscale 13, n.º 43 (2021): 18044–53. http://dx.doi.org/10.1039/d1nr05474k.

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Photoredox organic transformation have been growing, and this perspective highlights recent advances in mechanistic understanding, providing strategies to construct high efficiency and low-cost photocatalytic systems.
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38

Lin, Qiong, Yue-Hua Li, Zi-Rong Tang y Yi-Jun Xu. "Valorization of Biomass-Derived Platform Molecules via Photoredox Sustainable Catalysis". Transactions of Tianjin University 26, n.º 5 (28 de agosto de 2020): 325–40. http://dx.doi.org/10.1007/s12209-020-00271-7.

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Abstract The conversion of biomass into valuable chemicals has promise for application in biorefineries. Light-driven photoredox catalysis, with the typical features of green route and operation under mild conditions, is considered a promising strategy for renewable biomass or biomass-derived intermediates conversion into high-value-added chemical feedstocks. In this review, we strongly emphasize the recent advances in photocatalytic valorization of lignin model compounds and biomass-derived alcohols. We briefly summarize the advances in photocatalytic cleavage of the β-O-4 bond or C–C bond into usable chemicals in the lignin model. On the other hand, we clarify not only the hybrid system for cooperative biomass-relevant alcohols oxidation and hydrogen (H2) evolution but also the tunable accessibility to variation of the target products from the same alcohol reactant by catalyst design and optimization of reaction conditions. It is hoped that this review will inspire the rational design of photoredox catalysis-based systems toward efficient biomass-derived platform molecules valorization to obtain target-oriented valuable products.
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39

Jung, Jieun y Susumu Saito. "Recent Advances in Light-Driven Carbon–Carbon Bond Formation via Carbon Dioxide Activation". Synthesis 53, n.º 18 (3 de agosto de 2021): 3263–78. http://dx.doi.org/10.1055/a-1577-5947.

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AbstractCarbon dioxide (CO2) is an attractive renewable one-carbon (C1) feedstock in terms of its earth abundance, low cost, and non-toxicity. Developing new catalytic systems to realize the practical insertion of CO2 into organic molecules has been of great importance for ecological economics. In recent years, outstanding improvements have been carried out in the field of light-driven catalytic carboxylation via the activation of CO2 as the key reagent. In this short review, the recent developments of light-promoted carboxylation utilizing CO2 to synthesize value-added chemicals using a dual visible-light photoredox/transition-metal catalyst or a photoredox catalyst are highlighted.1 Introduction2 Visible-Light-Driven Carboxylation Using Transition-Metal Photocatalysts2.1 Transition-Metal-Catalyzed Carboxylation of Alkenes2.2 Transition-Metal-Catalyzed Carboxylation of C(sp2)–X (X = Cl, Br, OTf) Bonds2.3 Transition-Metal-Catalyzed Carboxylation of Alkynes2.4 Transition-Metal-Catalyzed Carboxylation of Carbons Attached to Nitrogen3 Light-Driven Carboxylation via Organo-Photocatalysis3.1 Photocatalytic Carboxylation of Alkenes3.2 Photocatalytic Carboxylation of C(sp3)–H Bonds4 Conclusion
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40

Koike, Takashi y Munetaka Akita. "Combination of organotrifluoroborates with photoredox catalysis marking a new phase in organic radical chemistry". Organic & Biomolecular Chemistry 14, n.º 29 (2016): 6886–90. http://dx.doi.org/10.1039/c6ob00996d.

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41

Ouyang, Xuan-Hui, Yang Li, Ren-Jie Song, Ming Hu, Shenglian Luo y Jin-Heng Li. "Intermolecular dialkylation of alkenes with two distinct C(sp3)─H bonds enabled by synergistic photoredox catalysis and iron catalysis". Science Advances 5, n.º 3 (marzo de 2019): eaav9839. http://dx.doi.org/10.1126/sciadv.aav9839.

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The functionalization of unactivated C(sp3)─H bonds represents one of the most powerful and most atom-economical tools for the formation of new carbon-based chemical bonds in synthesis. Although cross-dehydrogenative coupling reactions of two distinct C─H bonds for the formation of carbon-carbon bonds have been well investigated, controlled functionalizations of two or more different C(sp3)─H bonds across a functional group or a molecule (e.g., an alkene or alkyne) in a single reaction remain challenging. Here, we present a three-component dialkylation of alkenes with common alkanes and 1,3-dicarbonyl compounds via synergistic photoredox catalysis and iron catalysis for the synthesis of two functionalized 1,3-dicarbonyl compounds. Mechanistic studies suggest that the photoredox catalysis serves as a promotion system to allow the dialkylation to proceed under mild conditions by reducing the oxidation and reduction potentials of the iron intermediates and the reaction partners.
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42

Pawlowski, Robert, Filip Stanek y Maciej Stodulski. "Recent Advances on Metal-Free, Visible-Light- Induced Catalysis for Assembling Nitrogen- and Oxygen-Based Heterocyclic Scaffolds". Molecules 24, n.º 8 (18 de abril de 2019): 1533. http://dx.doi.org/10.3390/molecules24081533.

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Heterocycles are important class of structures, which occupy a major space in the domain of natural and bioactive compounds. For this reason, development of new synthetic strategies for their controllable synthesis became of special interests. The development of novel photoredox systems with wide-range application in organic synthesis is particularly interesting. Organic dyes have been widely applied as photoredox catalysts in organic synthesis. Their low costs compared to the typical photocatalysts based on transition metals make them an excellent alternative. This review describes proceedings since 2015 in the area of application of metal-free, visible-light-mediated catalysis for assembling various heterocyclic scaffolds containing five- and six-membered rings bearing nitrogen and oxygen heteroatoms.
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43

Kubota, Koji, Yadong Pang, Akira Miura y Hajime Ito. "Redox reactions of small organic molecules using ball milling and piezoelectric materials". Science 366, n.º 6472 (19 de diciembre de 2019): 1500–1504. http://dx.doi.org/10.1126/science.aay8224.

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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 developed through the piezoelectric effect. Here, we report that agitation of piezoelectric materials via ball milling reduces aryl diazonium salts. This mechanoredox system can be applied to arylation and borylation reactions under mechanochemical conditions.
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44

Griesbeck, Axel G. y Melissa Reckenthäler. "Homogeneous and heterogeneous photoredox-catalyzed hydroxymethylation of ketones and keto esters: catalyst screening, chemoselectivity and dilution effects". Beilstein Journal of Organic Chemistry 10 (19 de mayo de 2014): 1143–50. http://dx.doi.org/10.3762/bjoc.10.114.

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The homogeneous titanium- and dye-catalyzed as well as the heterogeneous semiconductor particle-catalyzed photohydroxymethylation of ketones by methanol were investigated in order to evaluate the most active photocatalyst system. Dialkoxytitanium dichlorides are the most efficient species for chemoselective hydroxymethylation of acetophenone as well as other aromatic and aliphatic ketones. Pinacol coupling is the dominant process for semiconductor catalysis and ketone reduction dominates the Ti(OiPr)4/methanol or isopropanol systems. Application of dilution effects on the TiO2 catalysis leads to an increase in hydroxymethylation at the expense of the pinacol coupling.
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45

Koike, Takashi y Munetaka Akita. "Fine Design of Photoredox Systems for Catalytic Fluoromethylation of Carbon–Carbon Multiple Bonds". Accounts of Chemical Research 49, n.º 9 (26 de agosto de 2016): 1937–45. http://dx.doi.org/10.1021/acs.accounts.6b00268.

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46

Hola, Emilia, Maciej Pilch y Joanna Ortyl. "Thioxanthone Derivatives as a New Class of Organic Photocatalysts for Photopolymerisation Processes and the 3D Printing of Photocurable Resins under Visible Light". Catalysts 10, n.º 8 (8 de agosto de 2020): 903. http://dx.doi.org/10.3390/catal10080903.

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In the present paper, novel thioxanthone-based compounds were synthesised and evaluated as a component of photoredox catalysts/photoinitiating systems for the free-radical polymerisation (FRP) of acrylates and the ring-opening cationic polymerisation (CP) of epoxy monomers. The performance of the obtained thioxanthones in two- and three-component photoinitiating systems, in combination with amines, iodonium or sulphonium salt, as well as with alkyl halide, for photopolymerisation processes upon exposure to light emitting diodes (LEDs) with a maximum emission of 405 nm and 420 nm, was investigated. The studied compounds act also as one-component free-radical photoinitiators. Fourier transform real-time infrared spectroscopy was used to monitor the kinetics of disappearance of the functional groups of the monomers during photoinitiated polymerisation. Excellent photoinitiating efficiency and high final conversions of functional groups were observed. Moreover, the influence of thioxanthone skeleton substitution on photoinitiating efficiency was discussed. The photochemical mechanism was also investigated through cyclic voltammetry. It was discovered that thioxanthone derivatives can be used as a metal-free photoredox catalyst active for both oxidative and reductive cycles. Furthermore, a photopolymerizable system based on novel thioxanthone derivatives in a stereolithography three-dimensional (3D) printing technology under visible sources of light was used. The effects of photoinitiator type system and monomer type in photoresins during 3D printing processes were explored. The outcome of this research is the development of high-performance visible photosensitive resins with improved photosensitivity obtained thanks to the development of entirely novel photoinitiating systems specifically adapted for this application.
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47

Rovis, Tomislav, Logan R. Beck, Katherine A. Xie, Samantha L. Goldschmid, Stavros K. Kariofillis, Candice L. Joe, Trevor C. Sherwood y Melda Sezen-Edmonds. "Red-Shifting Blue Light Photoredox Catalysis for Organic Synthesis: A Graphical Review". SynOpen 07, n.º 01 (febrero de 2023): 76–87. http://dx.doi.org/10.1055/s-0040-1720060.

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AbstractPhotoredox catalysis has revolutionized synthetic chemistry in recent decades. However, the field has traditionally used high-energy blue/ultraviolet light to activate chromophores. High-energy irradiation is associated with several drawbacks (e.g., activation of sensitive functional groups, undesired metal-ligand homolysis, background activation of molecules, and poor penetration), which has led researchers to develop alternative systems with lower energy deep red (DR) or near-infrared (NIR) light. This graphical review provides a concise overview of photophysical principles relevant to photoredox catalysis. Several applications that benefit from low-energy irradiation, such as large-scale batch reactions, photodynamic therapy, biological labeling, and multi-photon excitation are reviewed.
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48

Bédard, Anne-Catherine, Andrea Adamo, Kosi C. Aroh, M. Grace Russell, Aaron A. Bedermann, Jeremy Torosian, Brian Yue, Klavs F. Jensen y Timothy F. Jamison. "Reconfigurable system for automated optimization of diverse chemical reactions". Science 361, n.º 6408 (20 de septiembre de 2018): 1220–25. http://dx.doi.org/10.1126/science.aat0650.

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Chemical synthesis generally requires labor-intensive, sometimes tedious trial-and-error optimization of reaction conditions. Here, we describe a plug-and-play, continuous-flow chemical synthesis system that mitigates this challenge with an integrated combination of hardware, software, and analytics. The system software controls the user-selected reagents and unit operations (reactors and separators), processes reaction analytics (high-performance liquid chromatography, mass spectrometry, vibrational spectroscopy), and conducts automated optimizations. The capabilities of this system are demonstrated in high-yielding implementations of C-C and C-N cross-coupling, olefination, reductive amination, nucleophilic aromatic substitution (SNAr), photoredox catalysis, and a multistep sequence. The graphical user interface enables users to initiate optimizations, monitor progress remotely, and analyze results. Subsequent users of an optimized procedure need only download an electronic file, comparable to a smartphone application, to implement the protocol on their own apparatus.
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49

Selvakumar, Sermadurai. "Synergistic Dual Photoredox and Chiral Hydrogen Bonding Catalysis: Recent Advances". Asian Journal of Organic Chemistry, 23 de agosto de 2023. http://dx.doi.org/10.1002/ajoc.202300374.

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In the last two decades, chiral hydrogen bonding catalysis has been enormously utilized to trigger several valuable synthetic transformations. Similarly, modern day radical chemistry has witnessed the potency of visible light photoredox catalysis to generate radicals via single electron transfer pathway. Recently, their cooperative effect has proved to be a key strategy to access many elegant transformations that are only feasible under the synergistic action of these two catalytic systems. This dual catalytic system demonstrates high efficiency for introducing molecular complexity in an enantioselective fashion. In this mini review, we have compiled the most recent development of this dual catalytic system that surfaced in the last three years with particular attention paid to the mechanistic details and its substrate scope. We hope that this mini review will provide readers with a brief overview of the advancement and application of photoredox catalysts and chiral hydrogen bond donors for synergistic dual catalytic reactions.
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50

Li, Jinlian, Xing Chen, Shenxia Xie, Huabing Wang, Jiayu Mo y Huawen Huang. "Photoredox/Bismuth Relay Catalysis Enabling Reductive Alkylation of Nitroarenes with Aldehydes". Chemistry – A European Journal, 13 de mayo de 2024. http://dx.doi.org/10.1002/chem.202401456.

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The effective transition metal‐free photoredox/bismuth dual catalytic reductive dialkylation of nitroarenes with benzaldehydes has been reported. The nitroarene redution through visible light‐driven photoredox catalysis was integrated with subsequent reductive dialkylation of anilines under bismuth catalysis to enable the cascade reductive alkylation of nitroarenes with carbonyls. Salient features of this relay catalysis system include mild reaction conditions, no requirement for transition metal catalysts, easy handling, step‐economy, and high selectivity.
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