- Efficient halogenation synthesis method of aryl halide
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The invention discloses an efficient halogenation synthesis method of aryl halide. The method comprises the following step: in the presence of a catalyst (sulfoxide or oxynitride), a halogenation reagent and a solvent, carrying out a halogenation reaction on an aromatic ring compound to obtain the aryl halide. According to the present invention, in the presence of a catalyst (sulfoxide or nitrogenoxide), a halogenation reagent and a solvent, the aromatic ring is subjected to an efficient halogenation reaction, such that the very useful aryl halide can be obtained with high activity and high selectivity; and by adopting the method disclosed by the invention, aryl halides can be efficiently synthesized, and the method has a wide application prospect in actual production.
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Paragraph 0085-0089
(2021/03/31)
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- Unveiling Potent Photooxidation Behavior of Catalytic Photoreductants
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We describe a photocatalytic system that reveals latent photooxidant behavior from one of the most reducing conventional photoredox catalysts, N-phenylphenothiazine (PTH). This aerobic photochemical reaction engages difficult to oxidize feedstocks, such as benzene, in C(sp2)-N coupling reactions through direct oxidation. Mechanistic studies are consistent with activation of PTH via photooxidation and with Lewis acid cocatalysts scavenging inhibitors inextricably formed in this process.
- Targos, Karina,Williams, Oliver P.,Wickens, Zachary K.
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supporting information
p. 4125 - 4132
(2021/04/07)
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- Oxidative Photochlorination of Electron-Rich Arenes via in situ Bromination
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Electron-rich arenes are oxidatively photochlorinated in the presence of catalytic amounts of bromide ions, visible light, and 4CzIPN as organic photoredox catalyst. The substrates are brominated in situ in a first photoredox-catalyzed oxidation step, followed by a photocatalyzed ipso-chlorination, yielding the target compounds in high ortho/para regioselectivity. Dioxygen serves as a green and convenient terminal oxidant. The use of aqueous hydrochloric acid as the chloride source reduces the amount of saline by-products.
- Düsel, Simon Josef Siegfried,K?nig, Burkhard
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supporting information
p. 1491 - 1495
(2019/04/30)
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- Efficient Electrocatalysis for the Preparation of (Hetero)aryl Chlorides and Vinyl Chloride with 1,2-Dichloroethane
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Although the application of 1,2-dichloroethane (DCE) as a chlorinating reagent in organic synthesis with the concomitant release of vinyl chloride as a useful byproduct is a fantastic idea, it still presents a tremendous challenge and has not yet been achieved because of the harsh dehydrochlorination conditions and the sluggish C?H chlorination process. Here we report a bifunctional electrocatalysis strategy for the catalytic dehydrochlorination of DCE at the cathode simultaneously with anodic oxidative aromatic chlorination using the released HCl as the chloride source for the efficient synthesis of value-added (hetero)aryl chlorides. The mildness and practicality of the protocol was further demonstrated by the efficient late-stage chlorination of bioactive molecules.
- Liang, Yujie,Lin, Fengguirong,Adeli, Yeerlan,Jin, Rui,Jiao, Ning
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supporting information
p. 4566 - 4570
(2019/02/14)
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- Visible-light photocatalytic activation of N-chlorosuccinimide by organic dyes for the chlorination of arenes and heteroarenes
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A variety of arenes and heteroarenes are chlorinated in moderate to excellent yields using N-chlorosuccinimide (NCS) under visible-light activated conditions. A screening of known organic dye photocatalysts resulted in the identification of methylene green as the most efficient catalyst to use with NCS. According to mechanistic studies described within, the reaction is speculated to proceed via a single electron oxidation of NCS utilizing methylene green under visible-light photoredox pathway. The photo-oxidation of NCS amplifies the electrophilicity of the chlorine atom of the NCS, thus leading to enhanced reactivity as a chlorinating reagent with aromatic substrates.
- Rogers, David A.,Gallegos, Jillian M.,Hopkins, Megan D.,Lignieres, Austin A.,Pitzel, Amy K.,Lamar, Angus A.
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- Amplification of Trichloroisocyanuric Acid (TCCA) Reactivity for Chlorination of Arenes and Heteroarenes via Catalytic Organic Dye Activation
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Heteroarenes and arenes that contain electron-withdrawing groups are chlorinated in good to excellent yields (scalable to gram scale) using trichloroisocyanuric acid (TCCA) and catalytic Brilliant Green (BG). Visible-light activation of BG serves to amplify the electrophilic nature of TCCA, providing a mild alternative approach to acid-promoted chlorination of deactivated (hetero)aromatic substrates. The utility of the TCCA/BG system is demonstrated through comparison to other chlorinating reagents and by the chlorination of pharmaceuticals including caffeine, lidocaine, and phenazone.
- Rogers, David A.,Bensalah, Adam T.,Espinosa, Alvaro Tomas,Hoerr, John L.,Refai, Fares H.,Pitzel, Amy K.,Alvarado, Juan J.,Lamar, Angus A.
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supporting information
p. 4229 - 4233
(2019/06/17)
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- Electrophotocatalysis with a Trisaminocyclopropenium Radical Dication
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Visible-light photocatalysis and electrocatalysis are two powerful strategies for the promotion of chemical reactions. Here, these two modalities are combined in an electrophotocatalytic oxidation platform. This chemistry employs a trisaminocyclopropenium (TAC) ion catalyst, which is electrochemically oxidized to form a cyclopropenium radical dication intermediate. The radical dication undergoes photoexcitation with visible light to produce an excited-state species with oxidizing power (3.33 V vs. SCE) sufficient to oxidize benzene and halogenated benzenes via single-electron transfer (SET), resulting in C?H/N?H coupling with azoles. A rationale for the strongly oxidizing behavior of the photoexcited species is provided, while the stability of the catalyst is rationalized by a particular conformation of the cis-2,6-dimethylpiperidine moieties.
- Huang, He,Strater, Zack M.,Rauch, Michael,Shee, James,Sisto, Thomas J.,Nuckolls, Colin,Lambert, Tristan H.
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supporting information
p. 13318 - 13322
(2019/08/12)
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- A mild halogenation of pyrazoles using sodium halide salts and Oxone
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A mild, inexpensive, and operationally simple pyrazole halogenation method utilizing Oxone and sodium halide salts is reported. This work documents 17 examples of alkyl, aryl, allyl, and benzyl substituted 4-chloro and 4-bromopyrazoles, obtained in up to 93% yield. Reactions are performed in water under ambient conditions and generation of organic byproducts is avoided.
- Olsen, Kathryn L.,Jensen, Matthew R.,MacKay, James A.
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supporting information
p. 4111 - 4114
(2017/09/29)
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- Story of an Age-Old Reagent: An Electrophilic Chlorination of Arenes and Heterocycles by 1-Chloro-1,2-benziodoxol-3-one
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By the use of 1-chloro-1,2-benziodoxol-3-one, an age-old reagent, the practical and efficient chlorination method is achieved. This hypervalent iodine reagent is amenable not only to the chlorination of nitrogen-containing heterocycles but also to selected classes of arenes, BODIPY dyes, and pharmaceuticals. In addition, the advantages, such as easy preparation and recyclable, air- and moisture-stable, in combination with the success in a gram-scale experiment grant this reagent great potential for industrial application.
- Wang, Mengzhou,Zhang, Yanyan,Wang, Tao,Wang, Chao,Xue, Dong,Xiao, Jianliang
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supporting information
p. 1976 - 1979
(2016/06/01)
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- Selective Halogenation Using an Aniline Catalyst
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Electrophilic halogenation is used to produce a wide variety of halogenated compounds. Previously reported methods have been developed mainly using a reagent-based approach. Unfortunately, a suitable "catalytic" process for halogen transfer reactions has yet to be achieved. In this study, arylamines have been found to generate an N-halo arylamine intermediate, which acts as a highly reactive but selective catalytic electrophilic halogen source. A wide variety of heteroaromatic and aromatic compounds are halogenated using commercially available N-halosuccinimides, for example, NCS, NBS, and NIS, with good to excellent yields and with very high selectivity. In the case of unactivated double bonds, allylic chlorides are obtained under chlorination conditions, whereas bromocyclization occurs for polyolefin. The reactivity of the catalyst can be tuned by varying the electronic properties of the arene moiety of catalyst.
- Samanta, Ramesh C.,Yamamoto, Hisashi
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supporting information
p. 11976 - 11979
(2015/08/18)
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- CFBSA: a novel and practical chlorinating reagent
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A structurally simple, highly reactive chlorinating reagent, N-chloro-N-fluorobenzenesulfonylamine (CFBSA), was conveniently prepared from inexpensive Chloramine B in high yield. A wide range of substrates were chlorinated with it to obtain products in good to high yields and appropriate selectivity.
- Lu, Zehai,Li, Qingwei,Tang, Minghua,Jiang, Panpan,Zheng, Hao,Yang, Xianjin
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supporting information
p. 14852 - 14855
(2015/10/06)
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- Palauchlor: A practical and reactive chlorinating reagent
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Unlike its other halogen atom siblings, the utility of chlorinated arenes and (hetero)arenes are twofold: they are useful in tuning electronic structure as well as acting as points for diversification via cross-coupling. Herein we report the invention of a new guanidine-based chlorinating reagent, CBMG or "Palauchlor", inspired by a key chlorospirocyclization en route to pyrrole imidazole alkaloids. This direct, mild, operationally simple, and safe chlorinating method is compatible with a range of nitrogen-containing heterocycles as well as select classes of arenes, conjugated π-systems, sulfonamides, and silyl enol ethers. Comparisons with other known chlorinating reagents revealed CBMG to be the premier reagent.
- Rodriguez, Rodrigo A.,Pan, Chung-Mao,Yabe, Yuki,Kawamata, Yu,Eastgate, Martin D.,Baran, Phil S.
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supporting information
p. 6908 - 6911
(2014/06/09)
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- Scope and selectivity in palladium-catalyzed directed C-H bond halogenation reactions
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Palladium-catalyzed ligand directed C-H activation/halogenation reactions have been extensively explored. Both the nature of the?directing group and the substitution pattern on the arene ring of the substrate lead to different reactivity profiles, and often different and complementary products, in the presence and absence of the catalyst.
- Kalyani, Dipannita,Dick, Allison R.,Anani, Waseem Q.,Sanford, Melanie S.
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p. 11483 - 11498
(2007/10/03)
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