- Desymmetrization of Prochiral Cyclobutanones via Nitrogen Insertion: A Concise Route to Chiral γ-Lactams
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Asymmetric access to γ-lactams is achieved via a cyclobutanone ring expansion using widely available (1S,2R)-1-amino-2-indanol for chiral induction. Mechanistic analysis of the key N,O-ketal rearrangement reveals a Curtin–Hammett scenario, which enables a downstream stereoinduction (up to 88:12 dr) and is corroborated by spectroscopic, crystallographic, and computational studies. In combination with an easy deprotection protocol, this operationally simple sequence allows the synthesis of a range of optically pure γ-lactams, including those bearing all-carbon quaternary stereocenters. In addition, the formal synthesis of drug molecules baclofen, brivaracetam, and pregabalin further demonstrates the synthetic utility and highlights the general applicability of the presented method.
- Sietmann, Jan,Ong, Mike,Mück-Lichtenfeld, Christian,Daniliuc, Constantin G.,Wiest, Johannes M.
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supporting information
p. 9719 - 9723
(2021/03/16)
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- Palladium-Catalyzed Carbene Coupling Reactions of Cyclobutanone N-Sulfonylhydrazones
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Described herein are the palladium-catalyzed cross-coupling reactions of cyclobutanone-derived N-sulfonylhydrazones with aryl or benzyl halides, suggesting that the metal carbene process and β-hydride elimination can smoothly occur in strained ring system
- Ning, Xiaoqin,Chen, Yongke,Hu, Fangdong,Xia, Ying
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supporting information
p. 8348 - 8352
(2021/10/25)
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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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- Lewis Acid Catalyzed Ring-Opening Reaction of Cyclobutanones towards Conjugated Enones
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An unprecedented Fe-catalyzed ring-opening reaction of simple cyclobutanones is developed, which provides access to conjugated enones with good functional group tolerance in high yields under mild conditions. The product derivatization and gram-scale expe
- Gao, Jiqiang,Guo, Ziteng,Li, Zhongjuan,Liu, Chunhui,Liu, Yu,Qiu, Tingtian,Zhang, Min,Zhao, Jinbo
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supporting information
p. 6111 - 6114
(2021/12/16)
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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.
- Fang, Ping,Mei, Tian-Sheng,Shuai, Bin
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supporting information
p. 1637 - 1641
(2021/10/02)
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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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p. 9654 - 9658
(2021/12/14)
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- Absence of Intermediates in the BINOL-Derived Mg(II)/Phosphate-Catalyzed Desymmetrizative Ring Expansion of 1-Vinylcyclobutanols
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The catalyzed desymmetrizative ring expansion of alkenylcyclobutanols promoted by halofunctionalization of the alkene moiety with N-bromosuccinimide has been experimentally and computationally studied. The reaction yields highly enantioenriched cyclopenta
- Capel, Estefania,Merino, Pedro,Pedron, Manuel,Rodríguez-Rodríguez, Marta,Tejero, Tomas,Uria, Uxue,Vicario, Jose L.
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supporting information
(2022/01/04)
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- Synthesis of Cyclobutanones by Gold(I)-Catalyzed [2 + 2] Cycloaddition of Ynol Ethers with Alkenes
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A broad scope synthesis of cyclobutanones by gold(I)-catalyzed [2 + 2] cycloaddition of ynol ethers with alkenes has been developed. We also found that internal aryl ynol ethers can undergo (4 + 2) cycloaddition reaction with alkenes leading to the corres
- Zanini, Margherita,Cataffo, Andrea,Echavarren, Antonio M.
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supporting information
p. 8989 - 8993
(2021/11/20)
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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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- 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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- Radical C-C Bond Cleavage/Addition Cascade of Benzyl Cycloketone Oxime Ethers Enabled by Photogenerated Cyclic Iminyl Radicals
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A light-driven, metal-free, and iminyl radical-mediated ring-opening C-C bond cleavage/addition cascade of O-4-methoxybenzyl oxime ethers and alkenes is described for the first time. The reaction shows a broad substrate scope and high functional group compatibility with both components, giving the corresponding valuable oxo nitriles in generally good yields. Key to the success of this protocol is the generation of cyclic iminyl radicals from the O-4-methoxybenzyl oxime ethers via a photocatalytic hydrogen atom transfer (HAT) process. The proposed main pathway is also supported by the preliminary mechanistic studies.
- Wang, Peng-Zi,He, Bin-Qing,Cheng, Ying,Chen, Jia-Rong,Xiao, Wen-Jing
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supporting information
p. 6924 - 6929
(2019/09/30)
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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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- 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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- Manganese-Catalyzed Electrochemical Deconstructive Chlorination of Cycloalkanols via Alkoxy Radicals
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A manganese-catalyzed electrochemical deconstructive chlorination of cycloalkanols has been developed. This electrochemical method provides access to alkoxy radicals from alcohols and exhibits a broad substrate scope, with various cyclopropanols and cyclobutanols converted into synthetically useful β- and γ-chlorinated ketones (40 examples). Furthermore, the combination of recirculating flow electrochemistry and continuous inline purification was employed to access products on a gram scale.
- Allen, Benjamin D. W.,Hareram, Mishra Deepak,Seastram, Alex C.,McBride, Tom,Wirth, Thomas,Browne, Duncan L.,Morrill, Louis C.
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supporting information
p. 9241 - 9246
(2019/11/19)
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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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- 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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- Baeyer–Villiger monooxygenase-catalyzed desymmetrizations of cyclobutanones. Application to the synthesis of valuable spirolactones
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A series of γ-butyrolactone derivatives, including some spiranic ones, was obtained through desymmetrization of the corresponding prochiral 3-substituted cyclobutanones via Baeyer–Villiger monooxygenase (BVMO)-catalyzed oxidation. After reaction optimization using several commercial enzymes, both antipodes of various lactones were synthesized in most cases with >90% conversion and >80% enantiomeric excess under mild reaction conditions. In some cases alcohol formation was also observed (up to 40% conversion) as an undesired side reaction due to the presence of alcohol dehydrogenases in these preparations. Selected transformations were achieved on a 100 mg scale showing the possibilities of these oxidative biocatalysts as a new source of highly interesting compounds.
- Rodríguez-Mata, María,Lavandera, Iván,Gotor-Fernández, Vicente,Gotor, Vicente,García-Cerrada, Susana,Mendiola, Javier,de Frutos, óscar,Collado, Iván
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supporting information
p. 7268 - 7275
(2016/10/26)
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- Lactonization reactions through hydrolase-catalyzed peracid formation. Use of lipases for chemoenzymatic Baeyer-Villiger oxidations of cyclobutanones
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A one-pot chemoenzymatic method has been described for the synthesis of γ-butyrolactones starting from the corresponding ketones through a Baeyer-Villiger reaction. The approach is based on a lipase-catalyzed perhydrolysis for the formation of peracetic acid, which is the responsible for the ketone oxidation. Optimization studies have been performed in the oxidation of cyclobutanone, finding Candida antarctica lipase type B, ethyl acetate and urea-hydrogen peroxide complex as the best system. The relative ratio of these reagents has also been analyzed in depth. This synthetic approach has been successfully extended to a family of 3-substituted cyclobutanones in high substrate concentration, yielding the corresponding lactones with excellent isolated yields and purities, under mild reaction conditions and after a simple extraction protocol.
- González-Martínez, Daniel,Rodríguez-Mata, María,Méndez-Sánchez, Daniel,Gotor, Vicente,Gotor-Fernández, Vicente
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- A rhodium(I)-catalysed formal intramolecular C-C/C-H bond metathesis
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Phenylcyclobutanes underwent skeletal reorganisation in the presence of Wilkinson's catalyst to afford indanes through a cascade process involving chelation-assisted C-C bond cleavage and intramolecular C-H bond cleavage.
- Matsuda, Takanori,Yuihara, Itaru
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supporting information
p. 7393 - 7396
(2015/04/27)
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- Baeyer-Villiger Oxidation of Cyclobutanones with 10-Methylacridinium as an Efficient Organocatalyst
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Baeyer-Villiger oxidation of cyclobutanones is achieved in current developed protocol with 10-methylacridinium perchlorate (AcrH +ClO4-) as a novel organocatalyst both with irradiation at room temperature and without irradiation at elevated temperature. Excellent yields of the corresponding lactones are obtained and the possible mechanism has been proposed.
- Xu, Hua-Jian,Zhu, Feng-Fei,Shen, Yong-Ya,Wan, Xin,Feng, Yi-Si
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experimental part
p. 4145 - 4151
(2012/07/27)
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- Palladium-catalyzed, asymmetric Baeyer-Villiger oxidation of prochiral cyclobutanones with PHOX ligands
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Described in this report is a general method for the conversion of prochiral 3-substituted cyclobutanones to enantioenriched γ-lactones through a palladium-catalyzed Baeyer-Villiger oxidation using phosphinooxazoline ligands in up to 99% yield and 81% ee. Lactones of enantiopurity ≥93% could be obtained through a single recrystallization step. Importantly, 3,3-disubtituted cyclobutanones produced enantioenriched lactones containing a β-quaternary center.
- Petersen, Kimberly S.,Stoltz, Brian M.
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experimental part
p. 4352 - 4357
(2011/07/29)
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- SUBSTITUTED HETEROCYCLIC DERIVATIVES AND THEIR PHARMACEUTICAL USE AND COMPOSITIONS
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Compounds of the general Formula I, wherein X1, X2, X3, X4, X5, X6, X7, R1, R2, R4, R5, R6, R7, R8, R9, R10, Y1, n, m, p and q are defined as above, their preparation and their use as antimicrobial agents.
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Page/Page column 21
(2008/12/08)
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- Two-carbon ring expansion of cyclobutanone skeletons by nickel-catalyzed intermolecular alkyne insertion
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The reaction of cyclobutanone with an alkyne in the presence of a nickel(0) catalyst formally achieves intermolecular alkyne insertion between the carbonyl carbon and the α-carbon of a cyclobutanone, providing a six-membered carbocyclic skeleton.
- Murakami, Masahiro,Ashida, Shinji,Matsuda, Takanori
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p. 7540 - 7546
(2007/10/03)
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- Iridium-catalyzed ring cleavage reaction of cyclobutanone O-benzoyloximes providing nitriles
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(Chemical Equation Presented) Iridium-catalyzed ring cleavage reaction of cyclobutanone O-benzoyloximes in the presence of 9,10-dihydroanthracene and potassium carbonate proceeds to give saturated nitriles via C-C bond fission at the sterically more hinde
- Nishimura, Takahiro,Yoshinaka, Tomoaki,Nishiguchi, Yoshiki,Maeda, Yasunari,Uemura, Sakae
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p. 2425 - 2427
(2007/10/03)
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- Reactivity in acid-catalyzed carbon-carbon heterolysis
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Equilibrium and rate constants have been determined for the acid-catalyzed heterolysis of two alcohols, 9-xanthydrol and p-anisyldiphenylmethanol, and two sulfides, (9-xanthyl) methyl sulfide and (7-tropyl) methyl sulfide. These data together with literature information are compared with rate constants for acid-catalyzed C-C heterolysis of several (9-xanthyl) compounds, (7-tropyl) compounds, a set of 3-arylcyclobutanones, and two 2-arylnitrocyclopropanes, all of which fragment to carbocations plus a carbon-centered nucleofuge. The fragmentation mechanisms are shown to be A1 or A1(ion pair) except for the 2-arylnitrocyclopropanes which cleave in trifluoroacetic acid by a concerted mechanism. Rate comparisons among several unstrained substrate sets indicate that O-centered nucleofuges undergo acid-catalyzed heterolysis ca. 103-104 faster than S-centered nucleofuges and ca. 109-1014 faster than the C-centered nucleofuges used here. Factors assisting C-C heterolysis (and their effectiveness) include the acidity of the medium (strong); the basicity and nucleofugality of the nucleofuge (moderate); the stability of the electrofugic carbocation (strong); and relief of ring strain (enormous). Compared with acyclic cleavages, rate accelerations worth ca. 15 kcal/mol (for cyclobutanones) and ca. 27 kcal/mol (for nitrocyclopropanes) are found. These effects are discussed in terms of transition-state structure, aided by computational evidence.
- Cao, Weiguo,Erden, Ihsan,Grow, Richard H.,Keeffe, James R.,Song, Jiangao,Trudell, Mary B.,Wadsworth, Teri L.,Xu, Fu-Pei,Zheng, Ji-Bin
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p. 1009 - 1034
(2007/10/03)
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