- β-lactam synthesis via copper-catalyzed directed aminoalkylation of unactivated alkenes with cyclobutanone O-benzoyloximes
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A new protocol for amide-directed Cu-catalyzed aminoalkylation of unactivated alkenes using cyclobutanone oxime esters as alkyl radical donors is developed. Both primary and secondary alkyl groups can be selectively installed at the C4 position of termina
- Zhang, Heng,Lv, Xiaoyan,Yu, Hanrui,Bai, Zibo,Chen, Gong,He, Gang
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- Synthesis of β-nitro ketones from geminal bromonitroalkanes and silyl enol ethers by visible light photoredox catalysis
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Various β-nitro ketones, including those bearing a β-tertiary carbon, were prepared from geminal bromonitroalkanes and trimethylsilyl enol ethers of a broad range of ketones by visible light photoredox catalysis, which were then easily converted into β-amino ketones, 1,3-amino alcohols, α,β-unsaturated ketones, β-cyano ketones and γ-nitro ketones.
- Cao, Haoying,Ma, Shanshan,Feng, Yanhong,Guo, Yawen,Jiao, Peng
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p. 1780 - 1783
(2022/02/17)
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- Electro-reductive C-H cyanoalkylation of quinoxalin-2(1H)-ones
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Herein, we report a practical electro-reductive protocol for the direct C–H cyanoalkylation of quinoxalin-2(1H)-ones via iminyl radical-mediated ring opening. These mild reactions proceed under metal-, reductant-, and reagent-free conditions to provide synthetically useful cyanoalkylated quinoxalin-2(1H)-ones.
- Ding, Ling,Liu, Yuxiu,Niu, Kaikai,Wang, Qingmin
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supporting information
(2022/01/24)
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- Enantioselective Iridium-Catalyzed Allylation of Nitroalkanes: Entry to β-Stereogenic α-Quaternary Primary Amines
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The first systematic study of simple nitronate nucleophiles in iridium-catalyzed allylic alkylation is described. Using a tol-BINAP-modified π-allyliridiumC,O-benzoate catalyst, α,α-disubstituted nitronates substitute racemic branched alkyl-substituted al
- Jung, Woo-Ok,Mai, Binh Khanh,Spinello, Brian J.,Dubey, Zachary J.,Kim, Seung Wook,Stivala, Craig E.,Zbieg, Jason R.,Liu, Peng,Krische, Michael J.
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p. 9343 - 9349
(2021/07/19)
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- Nickel-Catalyzed Favorskii-Type Rearrangement of Cyclobutanone Oxime Esters to Cyclopropanecarbonitriles
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A nickel-catalyzed base-promoted rearrangement of cyclobutanone oxime esters to cyclopropanecarbonitriles was developed. The ring opening of cyclobutanone oxime esters occurs at the sterically less hindered side. A base-promoted nickelacyclobutane intermediate, formed in situ, is assumed to be involved in the formation of the product.
- Shuai, Bin,Fang, Ping,Mei, Tian-Sheng
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p. 1637 - 1641
(2021/10/02)
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- Synthesis of Phenanthridine and Quinoxaline Derivatives via Copper-Catalyzed Radical Cyanoalkylation of Cyclobutanone Oxime Esters and Vinyl Azides
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A copper-catalyzed radical cyclization of cyclobutanone oxime esters and vinyl azide is described. This method provides facile access to cyanoalkyl-substituted phenanthridines and quinoxalines with excellent isolated yields. Moreover, these reactions proceed under mild conditions with a board substrate scope and excellent functional group tolerance.
- Kong, Xianqiang,Li, Guodong,Liang, Qi,Lin, Long,Xu, Bo
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supporting information
p. 1948 - 1952
(2021/06/09)
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- Copper-Catalyzed Sulfonylation of Cyclobutanone Oxime Esters with Sulfonyl Hydrazides
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A copper-catalyzed radical cross-coupling of cyclobutanone oxime esters with sulfonyl hydrazides has been developed. The copper-based catalytic system proved crucial for cleavage of the C-C bond of cyclobutanone oximes and for selective C-S bond-formation involving persistent sulfonyl-metal radical intermediates. This protocol is distinguished by the low-cost catalytic system, which does not require ligand, base, or toxic cyanide salt, and by the use of readily accessible starting materials, as well as broad substrate scope, providing an efficient approach to various diversely substituted cyano-containing sulfones.
- Dong, Bingbing,Lu, Jiansha,Bao, Honghao,Zhang, Yuanyuan,Liu, Yingguo,Leng, Yuting
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supporting information
p. 3769 - 3776
(2021/07/14)
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- Metal-free chalcogenation of cycloketone oxime esters with dichalcogenides
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We report the metal-free chalcogenation of cycloketone oxime esters with dichalcogenides via a radical process. Because of the metal-free condition and use of readily accessible dichalcogenides, this method is an effective and green strategy for the synthesis of chalcogen-substituted butyronitrile.
- Ji, Liangshuo,Qiao, Jiamin,Liu, Junjie,Tian, Miaomiao,Lu, Kui,Zhao, Xia
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supporting information
(2021/06/15)
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- Visible-Light-Promoted Selenocyanation of Cyclobutanone Oxime Esters Using Potassium Selenocyanate
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We report the visible-light-promoted selenocyanation of cyclobutanone oxime esters using potassium selenocyanate in the presence of a fac-Ir(ppy)3 catalyst for the first time. Because of the mild conditions employed and use of readily accessible potassium selenocyanate, this method is an effective and green strategy for the synthesis of cyano and selenocyano bifunctional substituted alkanes.
- Zhao, Xia,Ji, Liangshuo,Gao, Yu,Sun, Tengteng,Qiao, Jiamin,Li, Ankun,Lu, Kui
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p. 11399 - 11406
(2021/09/02)
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- Dual Nickel/Ruthenium Strategy for Photoinduced Decarboxylative Cross-Coupling of α,β-Unsaturated Carboxylic Acids with Cycloketone Oxime Esters
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Herein, a dual nickel/ruthenium strategy is developed for photoinduced decarboxylative cross-coupling between α,β-unsaturated carboxylic acids and cycloketone oxime esters. The reaction mechanism is distinct from previous photoinduced decarboxylation of α,β-unsaturated carboxylic acids. This reaction might proceed through a nickelacyclopropane intermediate. The C(sp2)-C(sp3) bond constructed by the aforementioned reaction provides an efficient approach to obtaining various cyanoalkyl alkenes, which are synthetically valuable organic skeletons in organic and medicinal chemistry, under mild reaction conditions. The protocol tolerates many critical functional groups and provides a route for the modification of complex organic molecules.
- Lu, Xiao-Yu,Xia, Ze-Jie,Gao, Ang,Liu, Qi-Le,Jiang, Run-Chuang,Liu, Chuang-Chuang
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supporting information
p. 8829 - 8842
(2021/06/30)
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- Photoinduced Copper-Catalyzed Asymmetric C-O Cross-Coupling
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The construction of carbon-heteroatom bonds is one of the most active areas of research in organic chemistry because the function of organic molecules is often derived from the presence of heteroatoms. Although considerable advances have recently been achieved in radical-involved catalytic asymmetric C-N bond formation, there has been little progress in the corresponding C-O bond-forming processes. Here, we describe a photoinduced copper-catalyzed cross-coupling of readily available oxime esters and 1,3-dienes to generate diversely substituted allylic esters with high regio- and enantioselectivity (>75 examples; up to 95% ee). The reaction proceeds at room temperature under excitation by purple light-emitting diodes (LEDs) and features the use of a single, earth-abundant copper-based chiral catalyst as both the photoredox catalyst for radical generation and the source of asymmetric induction in C-O coupling. Combined experimental and density functional theory (DFT) computational studies suggest the formation of π-allylcopper complexes from redox-active oxime esters as bifunctional reagents and 1,3-dienes through a radical-polar crossover process.
- Chen, Jun,Liang, Yu-Jie,Wang, Peng-Zi,Li, Guo-Qing,Zhang, Bin,Qian, Hao,Huan, Xiao-Die,Guan, Wei,Xiao, Wen-Jing,Chen, Jia-Rong
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supporting information
p. 13382 - 13392
(2021/09/03)
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- Visible-Light Photoredox-Catalyzed Dicarbofunctionalization of Styrenes with Oxime Esters and CO2: Multicomponent Reactions toward Cyanocarboxylic Acids and γ-Keto Acids
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A photoredox-catalyzed dicarbofunctionalization of styrenes with oxime esters and CO2 has been achieved. Notably, a series of four-, five-, or six-membered cyclic ketone oximes worked well to furnish a wide range of ε-, ζ-, and η-cyanocarboxylic acids in good yields. Furthermore, a series of γ-keto acids also could be obtained by employing acyclic ketone oxime esters as the carbonyl radical precursor. It provides convergent access to diverse biologically important cyanocarboxylic and γ-keto acids.
- Bai, Junxue,Li, Miao,Zhou, Cong,Sha, Yu,Cheng, Jiang,Sun, Jianwei,Sun, Song
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supporting information
p. 9654 - 9658
(2021/12/14)
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- Minisci-Type C–H Cyanoalkylation of Heteroarenes Through N–O/C–C Bonds Cleavage
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A visible-light-induced C–H cyanoalkylation of heteroarenes was described, in which cycloketone oximes were readily transformed into carbon-centered radicals with a terminal cyano-group via N–O/C–C bonds cleavage in one phtochemical step. This reaction protocol displayed a broad substrate scope of heterocycle compounds, and it provided a promising strategy for the installation of cyanoalkyl groups onto heteroarenes.
- Jian, Yong,Chen, Ming,Yang, Chao,Xia, Wu-jiong
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p. 1439 - 1442
(2019/05/16)
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- Metal-Free sp3 C-SCF3 Coupling Reactions between Cycloketone Oxime Esters and S-trifluoromethyl 4-Methylbenzenesulfonothioate
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A novel sp3 C-SCF3 coupling reaction between cycloketone oxime esters and S-trifluoromethyl 4-methylbenzenesulfonothioate was achieved. Ethanol was found to facilitate this transformation by trapping the sulfonyl cation. The metal-free and photocatalyst-free reaction conditions, as well as the broad substrate scope, make this a green protocol for the synthesis of SCF3-substituted nitriles.
- Zhao, Xia,Tian, Miaomiao,Ji, Liangshuo,Liu, Junjie,Lu, Kui
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supporting information
p. 863 - 866
(2020/02/04)
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- O-Perfluoropyridin-4-yl Oximes: Iminyl Radical Precursors for Photo-or Thermal-Induced N-O Cleavage in C(sp2)-C(sp3) Bond Formation
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O-Perfluoropyridin-4-yl group was first installed onto cycloketone oximes as a new electrophore, which was proven to be efficient iminyl radical precursors under photocatalytic and thermal conditions. A range of O-perfluoropyridin-4-yl oximes were successfully utilized in C(sp2)-C(sp3) bond formations of quinoxalin-2(1H)-ones and alkenes, providing facile accesses to a range of functionalized alkylnitriles.
- Hu, Yuan-Zhuo,Li, Xu-Jie,Xia, Peng-Ju,Xiang, Hao-Yue,Yang, Hua,Ye, Zhi-Peng
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p. 3538 - 3547
(2020/03/23)
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- Directed Cobalt-Catalyzed anti-Markovnikov Hydroalkylation of Unactivated Alkenes Enabled by "co-H" Catalysis
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The earth-abundant cobalt-catalyzed anti-Markovnikov hydroalkylation of unactivated alkenes with oxime esters was achieved by introducing an 8-aminoquinoline directing group on the alkenes. The catalytic system, consisting of commercially available Co(acac)3 and PhMeSiH2, enables the construction of unfunctionalized C(sp3)-C(sp3) bonds and features exclusive anti-Markovnikov selectivity, good functional group tolerance, and the avoidance of an extra ligand, oxidant, or base. Mechanistic insight into this new catalytic system indicates the involvement of both alkyl radical and cobalt hydride intermediates.
- Yang, Dandan,Huang, Hai,Li, Meng-Hui,Si, Xiao-Ju,Zhang, He,Niu, Jun-Long,Song, Mao-Ping
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supporting information
p. 4333 - 4338
(2020/06/04)
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- Directing-Group-Based Strategy Enabling Intermolecular Heck-Type Reaction of Cycloketone Oxime Esters and Unactivated Alkenes
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A new type of coupling between unactivated olefins and nonstabilized alkyl radicals was achieved, which enabled the first intermolecular Heck-type reaction of cycloketone oxime esters and unactivated alkenes. This directing-group-based strategy was compatible with various unactivated alkenes and cyclobutanone-, cyclopentanone-, and cyclohexanone-derived oxime esters. Density functional theory calculations showed that both excellent regioselectivities and good diastereoselectivities could be ascribed to the 2-butanol-assisted concerted H-OBz elimination of the conformationally strained metallacyclic transition state.
- Cheng, Gui-Juan,Deng, Yi,Fu, Junkai,Li, Xuexiang,Wang, Hongwei,Zhao, Chunyang,Zhou, Yu
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supporting information
p. 3524 - 3530
(2020/04/30)
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- Photoinduced, Copper-Catalyzed Three-Component Annulation of gem-Dialkylthio Enynes
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Photoinduced, copper-catalyzed three-component radical annulation of gem-dialkylthio enynes, cyclobutanone oxime esters, and boronic acids was achieved, forming highly functionalized aryl thienyl sulfides with both good chemo- and diastereoselectivities. The reaction proceeds through a domino sequence involving cyanoalkyl radical-mediated intramolecular annulation of gem-dialkylthio enyne, alkenyl radical-promoted C(sp3)-S bond cleavage, and sulfur-centered radical-trapped Cu(II)-facilitated C-S cross-coupling. The protocol features simultaneous establishment of cyanoalkyl, cyclopentanone, and thiophene moieties and a thioether C-S bond in one pot with broad substrate scopes and versatile functional group tolerance under mild conditions.
- Lou, Jiang,Ma, Juan,Xu, Bao-Hua,Zhou, Yong-Gui,Yu, Zhengkun
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supporting information
p. 5202 - 5206
(2020/07/15)
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- Synthesis of trisubstituted alkenes by Ni-catalyzed hydroalkylation of internal alkynes with cycloketone oxime esters
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A method for Ni-catalyzed hydroalkylation of internal alkynes with cycloketone oxime esters was developed. The reaction has a broad substrate scope. This hydroalkylation shows excellent regio-and stereo-selectivity. This method enables readily available starting materials to be used to access a range of cyano-substituted single-configuration trisubstituted alkenes. These are valuable feedstock chemicals and are widely used in synthetic and medicinal chemistry.
- Lu, Xiao-Yu,Liu, Chuang-Chuang,Jiang, Run-Chuang,Yan, Lu-Yu,Liu, Qi-Le,Wang, Qing-Qing,Li, Jia-Mei
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supporting information
p. 14191 - 14194
(2020/11/24)
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- Copper-catalyzed ring-opening C(sp3)-N coupling of cycloketone oxime esters: Access to 1°, 2° and 3° alkyl amines
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A novel copper-catalyzed C(sp3)-N coupling of cycloketone oxime esters with nitrogen nucleophiles has been realized. All of the N-aryl/alkylanilines, anilines and benzophenone imine could be employed in this protocol to produce a variety of 1°, 2° and 3° alkyl amines in one or two steps. These resultant cyano-containing alkyl amines were proven to be versatile synthetic building blocks in a variety of chemical transformations.
- Tian, Li,Gao, Shuangqiu,Wang, Rui,Li, Yang,Tang, Chunlin,Shi, Lili,Fu, Junkai
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supporting information
p. 5347 - 5350
(2019/05/10)
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- Copper-Catalyzed Radical C-C Bond Cleavage and [4+1] Annulation Cascade of Cycloketone Oxime Esters with Enaminothiones
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Carbon-carbon bond formation is among the most important reactions in organic synthesis. Reconstruction of a carbon-carbon bond through ring-opening C-C bond cleavage of a strained carbocycle usually occurs via a thermodynamically preferable pathway. However, carbon-carbon bond formation through thermodynamically less favorable C-C bond cleavage has seldom been documented. Herein, we disclose an unusual C-C bond cleavage of cycloketone oxime esters for [4+1] annulation. Under anaerobic copper(I) catalysis, cycloketone oxime esters underwent regioselective, thermodynamically less favorable radical C-C bond cleavage followed by annulation with enaminothiones; that is, α-thioxo ketene N,S-acetals efficiently affording 2-cyanoalkyl-aminothiophene derivatives. Cyclobutanone, -pentanone, -hexanone, and -heptanone oxime esters could act as the effective C1 building blocks in the annulation reaction. An iminyl radical mechanism is proposed for the rare C-C bond cleavage/[4+1] annulation cascade.
- He, Yuan,Lou, Jiang,Wu, Kaikai,Wang, Hongmei,Yu, Zhengkun
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supporting information
(2019/02/14)
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- Photocatalytic, Phosphoranyl Radical-Mediated N-O Cleavage of Strained Cycloketone Oximes
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A photoinduced, phosphoranyl radical-mediated protocol for the direct N-O cleavage of strained cycloketone oximes via a polar/SET crossover process was developed for the first time. This visible-light-driven direct N-O activation mode for oxime offers beneficial features such as streamlined synthetic process and versatile photochemical reactivities. Consequently, the alkenes and α-trifluoromethyl alkenes with varied electronic and structural features acted as competent radical receptors in this protocol, enabling facile accesses to a range of elongated cyano and/or gem-difluoroalkene-bearing compounds.
- Xia, Peng-Ju,Ye, Zhi-Peng,Hu, Yuan-Zhuo,Song, Dan,Xiang, Hao-Yue,Chen, Xiao-Qing,Yang, Hua
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supporting information
p. 2658 - 2662
(2019/04/25)
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- Photoinduced, Copper-Catalyzed Radical Cross-Coupling of Cycloketone Oxime Esters, Alkenes, and Terminal Alkynes
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A photoinduced, copper-catalyzed three-component radical cross-coupling of cycloketone oxime esters, alkenes, and terminal alkynes is described for the first time. Key to the success of this process was the integration of photoinduced iminyl radical-mediated C-C bond cleavage with the conceptual simplicity of copper-catalyzed radical cross-coupling. This protocol provides access to cyanoalkyl-containing propargylic compounds in good yields.
- Chen, Jun,He, Bin-Qing,Wang, Peng-Zi,Yu, Xiao-Ye,Zhao, Quan-Qing,Chen, Jia-Rong,Xiao, Wen-Jing
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supporting information
p. 4359 - 4364
(2019/06/08)
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- Photoredox-Catalyzed Sulfonylation of O-Acyl Oximes via Iminyl Radicals with the Insertion of Sulfur Dioxide
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A multicomponent sulfonylation of O-acyl oximes via iminyl radicals with the insertion of sulfur dioxide under photoredox catalysis is achieved. This multicomponent reaction of O-acyl oximes, potassium metabisulfite, alkenes, and nucleophiles under visible-light irradiation is efficient, giving rise to a range of sulfones in moderate to good yields. A broad reaction scope is presented with good functional group compatibility.
- Zhang, Jun,Li, Xiaofang,Xie, Wenlin,Ye, Shengqing,Wu, Jie
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supporting information
p. 4950 - 4954
(2019/06/24)
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- Transition-Metal-Promoted Direct C?H Cyanoalkylation and Cyanoalkoxylation of Internal Alkenes via Radical C?C Bond Cleavage of Cycloketone Oxime Esters
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Transition-metal-catalyzed alkyl-Heck-type cross-coupling of olefinic C?H bonds has been a challenge in the C?H activation area. Herein, we report FeCl3-promoted efficient direct C?H cyanoalkylation of internal alkenes, that is, ketene dithioacetals, with cycloketone oxime esters via radical C?C bond cleavage under the redox-neutral conditions. With CuCl2 as the catalyst under a dioxygen atmosphere direct C?H cyanoalkoxylation of the same internal alkenes was achieved. The cyanoalkylated tetrasubstituted alkene products could be diversely transformed to cyanoalkyl-funtionalized N- and S-heterocyclic compounds. The mechanistic studies have revealed that these C?H cyanoalkylation and cyanoalkoxylation reactions proceed through a radical pathway. (Figure presented.).
- Lou, Jiang,He, Yuan,Li, Yunlong,Yu, Zhengkun
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supporting information
p. 3787 - 3799
(2019/07/10)
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- Visible-light-induced radical cascade cyclization of oxime esters and aryl isonitriles: Synthesis of cyclopenta[: B] quinoxalines
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A visible-light-induced radical cascade cyclization of aryl isonitriles and cyclobutanone oxime esters for the synthesis of cyclopenta[b]quinoxalines has been accomplished for the first time. The key to the success of this process was the integration of the in situ-formed nitrile radical followed by the cascade radical isonitrile/nitrile insertion-cyclization. The easy introduction of substituents for both substrates and the high functional group tolerance of the reaction make it an efficient strategy to give various quinoxaline derivatives in moderate to good yields.
- Yuan, Yao,Dong, Wu-Heng,Gao, Xiao-Shuang,Xie, Xiao-Min,Zhang, Zhao-Guo
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supporting information
p. 11900 - 11903
(2019/10/11)
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- Visible light-induced palladium-catalyzed ring opening β-H elimination and addition of cyclobutanone oxime esters
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A palladium catalyst under visible light irradiation activates cyclobutanone oxime ester through single electron transfer to induce radical ring opening to generate hybrid cyanoalkyl Pd(i) radical species. Hybrid cyanoalkyl Pd(i) radical species can undergo either β-H elimination to deliver (E)-4-arylbut-3-enenitrile or undergo radical addition with silyl enol ether and enamide to generate δ-cyano ketones. A dual ligand system composed of two phosphine ligands is essential for the high reactivity.
- Xing, Wei-Long,Shang, Rui,Wang, Guang-Zu,Fu, Yao
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supporting information
p. 14291 - 14294
(2019/12/02)
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- Nickel-Catalyzed Thiolation and Selenylation of Cycloketone Oxime Esters with Thiosulfonate or Seleniumsulfonate
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A nickel-catalyzed ring opening and, subsequently, reductive cross-coupling of cycloketone oxime esters with thiosulfonate or seleniumsulfonate are reported, which involves C-C bond cleavage and C(sp3)-S or C(sp3)-Se bond formation. Notably, S-aryl/alkyl sulfonothioates and Se-alkyl seleniumsulfonothioates could be employed in this reaction to afford a variety of 1° and 2° alkyl sulfides, aryl sulfides, and 1° and 2° alkyl selenides in one step. This strategy features easily available substrates and mild reaction conditions.
- Li, Jian,Wang, Shun-Yi,Ji, Shun-Jun
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p. 16147 - 16156
(2019/12/27)
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- Cu-Catalyzed Redox-Neutral Ring Cleavage of Cycloketone O-Acyl Oximes: Chemodivergent Access to Distal Oxygenated Nitriles
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A chemodivergent copper-catalyzed ring opening of cycloketone oximes via radical-mediated C-C bond cleavage under redox-neutral conditions is described. This method allows the divergent synthesis of γ- and δ-acyloxylated, alkoxylated, and hydroxylated nitriles while avoiding the use of toxic cyanide reagents. Moreover, these reactions proceed under very mild conditions with good functional group tolerance. Notably, ring-opening reactions of the less-strained substrate cyclopentanone oxime also proceeded well under the established conditions.
- Ai, Wenying,Liu, Yaqian,Wang, Qian,Lu, Zhonglin,Liu, Qiang
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supporting information
p. 409 - 412
(2018/01/27)
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- A Visible-Light-Driven Iminyl Radical-Mediated C?C Single Bond Cleavage/Radical Addition Cascade of Oxime Esters
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A room-temperature, visible-light-driven N-centered iminyl radical-mediated and redox-neutral C?C single bond cleavage/radical addition cascade reaction of oxime esters and unsaturated systems has been accomplished. The strategy tolerates a wide range of O-acyl oximes and unsaturated systems, such as alkenes, silyl enol ethers, alkynes, and isonitrile, enabling highly selective formation of various chemical bonds. This method thus provides an efficient approach to various diversely substituted cyano-containing alkenes, ketones, carbocycles, and heterocycles.
- Yu, Xiao-Ye,Chen, Jia-Rong,Wang, Peng-Zi,Yang, Meng-Nan,Liang, Dong,Xiao, Wen-Jing
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supporting information
p. 738 - 743
(2017/12/26)
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- Copper-catalyzed tandem aerobic oxidative cyclization for the synthesis of 4-cyanoalkylpyrrolo[1,2-a]quinoxalines from 1-(2-aminophenyl)pyrroles and cyclobutanone oxime esters
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A copper-catalyzed tandem ring-opening/cyclization reaction for the synthesis of 4-cyanoalkylpyrrolo[1,2-a]quinoxalines from 1-(2-aminophenyl)pyrroles and cyclobutanone oxime esters has been developed. This reaction involves C-C bond cleavage and C-C and C-N bond constructions with good functional group tolerance. A wide range of products are obtained in moderate to good yields under mild conditions.
- An, Zhenyu,Jiang, Yong,Guan, Xin,Yan, Rulong
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supporting information
p. 10738 - 10741
(2018/09/29)
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- Photocatalytic Neophyl Rearrangement and Reduction of Distal Carbon Radicals by Iminyl Radical-Mediated C?C Bond Cleavage
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The control of selectivity in the reactions of the highly reactive open-shell carbon radicals is an attractive but often challenging task. Building on the strategy of photoinduced iminyl radical-mediated C?C bond cleavage, we have developed photocatalytic neophyl rearrangement and reduction of distal carbon radicals under visible light irradiation of O-acyl oximes. This mild protocol tolerates a wide range of readily available O-acyl oximes, enabling facile synthesis of diversely substituted α,β-unsaturated nitriles and β-functionalized saturated nitriles in a highly selective manner. (Figure presented.).
- Yu, Xiao-Ye,Wang, Peng-Zi,Yan, Dong-Mei,Lu, Bin,Chen, Jia-Rong,Xiao, Wen-Jing
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supporting information
p. 3601 - 3606
(2018/09/18)
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- A photoredox catalyzed iminyl radical-triggered C-C bond cleavage/addition/Kornblum oxidation cascade of oxime esters and styrenes: synthesis of ketonitriles
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A photoredox-catalyzed iminyl radical-triggered C-C bond cleavage/addition/Kornblum oxidation cascade of cycloketone oxime esters and styrenes in DMSO is described. This three-component, one-pot procedure features mild conditions, a broad substrate scope, and high functional group tolerance, providing an efficient approach to access diversely functionalized ketonitriles.
- He, Bin-Qing,Yu, Xiao-Ye,Wang, Peng-Zi,Chen, Jia-Rong,Xiao, Wen-Jing
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supporting information
p. 12262 - 12265
(2018/11/21)
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- Copper-Catalyzed Coupling Reactions of Cyclobutanone Oxime Esters with Sulfur Nucleophiles at Room Temperature
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A copper-catalyzed iminyl radical-mediated C-C bond cleavage/cross-coupling tandem reaction of cyclobutanone oxime esters with aryl thiols in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) at room temperature was developed, and aryl cyanopropyl sulfides were smoothly synthesized in 20-88% yields. By altering the copper reagent and the molar ratio of cyclobutanone oxime ester/aryl thiol/DBU, substitutional product N-arylthio cyclobutanone imines were selectively generated in 50-91% yields. Using this protocol, C-S bond and N-S bond formations using aryl thiols as sulfur sources were realized under very mild conditions without the use of photocatalysis and electrocatalysis techniques.
- He, Mingchuang,Yan, Zhaohua,Zhu, Fuyuan,Lin, Sen
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p. 15438 - 15448
(2019/01/04)
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- Copper-Catalyzed Intermolecular Heck-Like Coupling of Cyclobutanone Oximes Initiated by Selective C?C Bond Cleavage
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The first example of intermolecular olefination of cyclobutanone oximes with alkenes via selective C?C bond cleavage leading to the synthesis of nitriles in the presence of a cheap copper catalyst is reported. The procedure is distinguished by mild and safe reaction conditions that avoid ligand, oxidant, base, or toxic cyanide salt. A wide scope of cyclobutanones and olefin coupling components can be used without compromising efficiency and scalability. The alternative visible-light-driven photoredox process for this coupling reaction was also uncovered.
- Zhao, Binlin,Shi, Zhuangzhi
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supporting information
p. 12727 - 12731
(2017/09/08)
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- Divergent Iron-Catalyzed Coupling of O-Acyloximes with Silyl Enol Ethers
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An iron-catalyzed coupling reaction of O-acyloximes and O-benzoyl amidoximes with silyl enol ethers is reported. The protocol provides access to functionalized pyrroles, 1,6-ketonitriles, pyrrolines and imidazolines via carbon-centered radicals generated from an initially formed iminyl radical. The intramolecular cyclization and ring-opening processes of the iminyl radical take place preferentially over reactions that proceed through a 1,3-hydrogen transfer, providing insights into iron-catalyzed reactions with oxime derivatives. The cheap and environmentally friendly iron catalyst, the broad substrate scope and the functional group compatibility make this protocol useful for synthesis of valuable nitrogen-containing products.
- Yang, Hai-Bin,Selander, Nicklas
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supporting information
p. 1779 - 1783
(2017/02/15)
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- Oxime rearrangements: Ab initio calculations and reactions in the solid state
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Rearrangements of oximes in reactions with strong Lewis acids may include Beckmann alkyl group shift or hydride migration. These reaction mechanisms were studied by FT-IR spectroscopy in solid superacid cryogenic matrices and supported by ab initio calculations. It was found that cyclic oximes with smaller rings (cyclobutanone oxime and cyclopentanone oxime) undergo hydride migration rather than alkyl group shift. Resulting aminoallyl cations were isolated in superacid cryogenic matrix and characterized spectroscopically. Cyclohexanone oxime rearranges by a classical Beckmann mechanism to a cyclic seven-membered nitrylium cation, which was also observed in the matrix. The ion is found to be persistent in solid superacid medium despite the highly strained non-linear carbon nitrogen triple bond. It seems that hydrogen bonds with halogens formed in the Lewis acid-oxime complex could play an important role in the hydrogen migrations.
- Simunic-Meznaric, Vesna,Mihalic, Zlatko,Vancik, Hrvoj
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p. 2154 - 2158
(2007/10/03)
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