- β-Diazocarbonyl Compounds: Synthesis and their Rh(II)-Catalyzed 1,3 C?H Insertions
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Herein, we describe the first electrophilic diazomethylation of ketone silyl enol ethers with diazomethyl-substituted hypervalent iodine reagents that gives access to unusual β-diazocarbonyl compounds. The potential of this unexplored class of diazo compounds for the development of new reactions was demonstrated by the discovery of a rare Rh-catalyzed intramolecular 1,3 C?H carbene insertion that led to complex cyclopropanes with excellent stereocontrol.
- Jiang, Liyin,Wang, Zhaofeng,Armstrong, Melanie,Suero, Marcos G.
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supporting information
p. 6177 - 6184
(2021/02/01)
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- Versatile and base-free copper-catalyzed α-arylations of aromatic ketones using diaryliodonium salts
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A ligand and base-free copper catalyzed synthetic method for the efficient α-arylation of aromatic ketones is described. In order to avoid strong bases, ketone-derived silyl enol ethers were employed. Their reaction with diaryliodonium salts as aryl source provided the intermolecular C–C coupling displaying good functional group tolerance and requiring low catalyst loading.
- Bouquin, Maxime,Jaroschik, Florian,Taillefer, Marc
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supporting information
(2021/06/11)
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- Iron-Catalyzed Ring-Opening Reactions of Cyclopropanols with Alkenes and TBHP: Synthesis of 5-Oxo Peroxides
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The ring opening of cyclopropanols is rarely used in multicomponent reactions. Herein we report the three-component reaction of cyclopropanols with alkenes and tert-butyl hydroperoxide (TBHP) catalyzed by an iron catalyst. This protocol enables the incorporation of both the β-carbonyl fragment and a peroxy unit across the C=C double bond regioselectively, thus allowing an efficient, facile access to 5-oxo peroxides. Modification of the biologically active molecules and various downstream derivatizations of the peroxides are also demonstrated.
- Lou, Chenhao,Wang, Xin,Lv, Leiyang,Li, Zhiping
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supporting information
p. 7608 - 7612
(2021/10/02)
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- Three-Component Coupling of Acyl Fluorides, Silyl Enol Ethers, and Alkynes by P(III)/P(V) Catalysis
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We report herein on the phosphine-catalyzed hydrovinylation reaction by three-component coupling of acyl fluorides, silyl enol ethers, and alkynoates. The key to the success of the reaction is the formal transmetalation between pentacoordinate P(V) species (i.e., fluorophosphorane) and a silyl enol ether, which allows for C-C bond formation between the polarity-mismatched sites. The bond formation that cannot be attained even by transition metal catalysis is accomplished by a P(III)/P(V) manifold.
- Fujimoto, Hayato,Kusano, Momoka,Kodama, Takuya,Tobisu, Mamoru
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supporting information
p. 18394 - 18399
(2021/11/22)
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- Photoinduced Deaminative Alkylation for the Synthesis of γ-Ketoesters via Electron Donor–Acceptor Complex Formation
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Visible-light-induced deaminative alkylation of Katritzky salts with silyl enol ethers has been developed. The reaction can proceed efficiently through electron donor–acceptor complex formation, avoiding the use of precious metal complexes or synthetically elaborate organic dyes. A series of functionalized γ-ketoesters was successfully obtained with good functional group tolerance and compatibility under mild and straightforward conditions.
- Wang, Jia-Xin,Ge, Wei,Xing, Wei-Long,Fu, Ming-Chen
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supporting information
p. 18224 - 18231
(2021/12/13)
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- σ-Bond initiated generation of aryl radicals from aryl diazonium salts
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σ-Bond nucleophiles and molecular oxygen transform aryl diazonium salts into aryl radicals. Experimental and computational studies show that Hantzsch esters transfer hydride to aryl diazonium species, and that oxygen initiates radical fragmentation of the diazene intermediate to produce aryl radicals. The operational simplicity of this addition-fragmentation process for the generation of aryl radicals, by a polar-radical crossover mechanism, has been illustrated in a variety of bond-forming reactions.
- Chan, Bun,McErlean, Christopher S. P.,Nashar, Philippe E.,Tatunashvili, Elene
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supporting information
p. 1812 - 1819
(2020/03/17)
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- Direct synthesis of 2-arylazulenes by [8+2] cycloaddition of 2: H -cyclohepta [b] furan-2-ones with silyl enol ethers
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We developed a procedure for the direct synthesis of 2-arylazulenes, which were obtained in moderate to excellent yields, by [8+2] cycloaddition of 2H-cyclohepta[b]furan-2-ones with aryl-substituted silyl enol ethers. The structures of some 2-arylazulenes were clarified by single-crystal X-ray analysis. The 2-phenylazulene derivatives obtained by this study showed noticeable fluorescence in acidic media.
- Shoji, Taku,Sugiyama, Shuhei,Kobayashi, Yoshiaki,Yamazaki, Akari,Ariga, Yukino,Katoh, Ryuzi,Wakui, Hiroki,Yasunami, Masafumi,Ito, Shunji
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supporting information
p. 1485 - 1488
(2020/02/13)
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- Aryl Pyrazoles from Photocatalytic Cycloadditions of Arenediazonium
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A photocatalytic synthesis of 1,5-diaryl pyrazoles from arenediazoniums and arylcyclopropanols is reported. The reaction proceeded under mild conditions (rt, 20 min) with catalytic [Ru(bpy)3]2+ under blue-light irradiation and exhibited compatibility with several functional groups (e.g., I, SF5, SO2NH2, N3, CN) and perfect levels of regiocontrol. Mechanistic studies (luminescence spectroscopy, CV, DFT, radical trapping, quantum yield determination) documented an initial oxidative quenching of the excited photocatalyst and the operation of a radical-chain mechanism.
- Cardinale, Luana,Neumeier, Michael,Majek, Michal,Jacobi Von Wangelin, Axel
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supporting information
p. 7219 - 7224
(2020/10/02)
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- Palladium-Catalyzed [5 + 2] Annulation of Vinylethylene Carbonates with Barbiturate-Derived Alkenes
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A palladium/XantPhos-catalyzed [5 + 2] annulation of VECs with electron-deficient alkenes having an isolated carbon-carbon double bond has been developed to afford spirobarbiturate-tetrahydrooxepines. This study provides an expedient assembly of biologically interesting spirobarbiturate-tetrahydrooxepines. The easy scalability and versatile transformability of the reaction products were also exhibited.
- Chen, Yuehua,Deng, Hao,Gao, Xing,Guo, Hongchao,Jiang, Feng,Wang, Wei,Wu, Yongjun,Zhu, Dongyu
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supporting information
p. 7158 - 7163
(2020/10/02)
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- C?O coupling of Malonyl Peroxides with Enol Ethers via [5+2] Cycloaddition: Non-Rubottom Oxidation
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Malonyl peroxides act both as oxidants and reagents for C?O coupling in reactions with methyl and silyl enol ethers. In the proposed conditions, the oxidative C?O coupling of malonyl peroxides with enol ethers selectively proceeds, bypassing the traditional Rubottom hydroxylation of enol ethers by peroxides. It was observed that the oxidative [5+2] cycloaddition of malonyl peroxides and enol ethers is the key stage of the discovered process. Oxidative C?O coupling of silyl enol ethers leads to the formation of α-acyloxyketones with a free carboxylic acid group. A specially developed preparative one-pot procedure transforms ketones via silyl enol ethers formation and the following coupling into α-acyloxyketones with yields 35–88%. The acid-catalyzed coupling with methyl enol ethers gives remarkable products while retaining the easily oxidizable enol fragment. Furthermore, these molecules contain a free carboxylic acid group, thus these nontrivial products contain two usually incompatible acid and enol ether groups. (Figure presented.).
- Vil', Vera A.,Gorlov, Evgenii S.,Bityukov, Oleg V.,Barsegyan, Yana A.,Romanova, Yulia E.,Merkulova, Valentina M.,Terent'ev, Alexander O.
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supporting information
p. 3173 - 3181
(2019/05/15)
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- Photoredox-Catalyzed Generation of Sulfamyl Radicals: Sulfonamidation of Enol Silyl Ether with Chlorosulfonamide
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A novel and practical photoredox-catalyzed generation of sulfamyl radicals followed by radical sulfonamidation of enol silyl ether has been described. Diverse functionalized β-ketosulfonamides were prepared in modest to excellent yields under mild and economic reaction conditions through the present catalytic protocol. Furthermore, the methodology developed provides an efficient and convenient approach to the synthesis of the antiseizure drug Zonisamide.
- Luo, Qiyu,Mao, Runyu,Zhu, Yan,Wang, Yonghui
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p. 13897 - 13907
(2019/11/11)
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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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- Organosilicon Reducing Reagents for Stereoselective Formations of Silyl Enol Ethers from α-Halo Carbonyl Compounds
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Salt-free stereoselective synthesis of silyl enol ethers was achieved by treating α-halo carbonyl compounds with 2,3,5,6-tetramethyl-1,4-bis(trimethylsilyl)-1,4-dihydropyrazine. In this reaction, easily removable trimethylsilyl halides and 2,3,5,6-tetramethylpyrazine were generated as the reaction byproducts. Due to the inertness of the reaction byproducts, we found a one-pot transformation of the in situ generated silyl enol ethers into various α-functionalized carbonyls by reaction with Togni-II reagent or aldehydes.
- Pramanik, Suman,Rej, Supriya,Kando, Shun,Tsurugi, Hayato,Mashima, Kazushi
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p. 2409 - 2417
(2018/02/23)
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- Photoredox-Catalyzed Decarboxylative Alkylation of Silyl Enol Ethers to Synthesize Functionalized Aryl Alkyl Ketones
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Photoredox-catalyzed decarboxylative alkylation of silyl enol ethers has been developed. Diverse functionalized aryl alkyl ketones were afforded in modest to good yields using N-(acyloxy)phthalimide as an easy access alkyl radical source under mild and operationally simple conditions. The excellent performance of drug molecules such as fenbufen and indomethacin and naturally occurring carboxylic acids such as stearic acid and dehydrocholic acid further demonstrated the practicability of the reaction.
- Kong, Weiguang,Yu, Changjiang,An, Hejun,Song, Qiuling
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supporting information
p. 349 - 352
(2018/01/28)
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- Enantioselective Mukaiyama–Michael Reaction Catalyzed by a Chiral Rhodium Complex Based on Pinene-Modified Pyridine Ligands
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The rhodium complex Λ-Rh1 containing chiral pinene-modified pyridine ligands is prepared through a two-step synthetic procedure; it exhibits excellent reactivity and enantiocontrol towards the enantioselective Mukaiyama–Michael reaction of α,β-unsaturated 2-acyl imidazoles with silyl enol ethers, affording enantioenriched 1,5-dicarbonyl compounds in good yields (up to 99 %) with excellent enantioselectivities (up to 99 % ee).
- Gong, Jun,Wan, Qian,Kang, Qiang
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supporting information
p. 2484 - 2488
(2018/05/04)
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- Ring-Opening Diarylation of Siloxydifluorocyclopropanes by Ag(I) Catalysis: Stereoselective Construction of 2-Fluoroallylic Scaffold
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A silver-catalyzed, defluorination ring-opening diarylation of siloxy 2,2-difluorocyclopropanes, with two arenes, to directly prepare polysubstituted 2-fluoroallylic compounds, is described. This multicomponent reaction proceeds smoothly in good stereoselectivity, which is due to a chelation-controlled addition of arenes to α-fluorinated ketone intermediate.
- Song, Xiaoning,Xu, Cong,Du, Dongxu,Zhao, Ziming,Zhu, Dongsheng,Wang, Mang
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supporting information
p. 6542 - 6545
(2017/12/26)
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- Synthesis of β-Amino Ketones by Addition of Aryl Methyl Ketones to Sulfinimines: Application to the Total Synthesis of HPA-12, Norsedamine, and Sedamine
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Synthesis of β-sulfinamido ketones was accomplished by the addition of silyl enol ethers derived from arylmethyl ketones to chiral sulfinimines in excellent yield and selectivity. Application of the formed β-amino substituted ketones is exemplified in the total synthesis of sphingolipid HPA-12 and the sedamine alkaloids.
- Reddy, Arava Amaranadha,Prasad, Kavirayani R.
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p. 13488 - 13499
(2017/12/26)
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- Studies on synthesis of a novel, broad-spectrum antitumor compound 2-(1-hydroxy-4-oxo-cyclohexa-2, 5-dienyl)-pyran-4-one
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Based on the previous studies, used protoapigenone as a model, we adopted chemical synthesis methods to develop the new compounds. It was specifically named as 2-(1-hydroxy-4-oxo-2, 5-cyclohexadien-1-yl)-4H-Pyran-4-one, including a core group: 1-hydroxycy
- Wang, Xiaohua,Yang, Liu,Xue, Pingping,Ruan, Jinlan
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- Enantioselective N-Heterocyclic Carbene Catalyzed Synthesis of Functionalized Indenes
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An enantioselective NHC (N-heterocyclic carbene) catalyzed synthesis of indenes from bifunctional α,β-unsaturated acyl fluorides and TMS enol ethers has been discovered. The reaction has broad generality (31 examples) and proceeds with high levels of enantioselectivity (most >92:8 er). Mechanistically the reaction likely occurs via a Michael/β-lactonization/decarboxylation sequence. Derivatization studies and limitations are discussed.
- Zhang, Changhe,Lupton, David W.
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supporting information
p. 4456 - 4459
(2017/09/11)
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- Visible-Light-Induced Alkoxyl Radical Generation Enables Selective C(sp3)-C(sp3) Bond Cleavage and Functionalizations
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The alkoxyl radical is an important reactive intermediate in mechanistic studies and organic synthesis; however, its current generation from alcohol oxidation heavily relies on transition metal activation under strong oxidative conditions. Here we report the first visible-light-induced alcohol oxidation to generate alkoxyl radicals by cyclic iodine(III) reagent catalysis under mild reaction conditions. The β-fragmentation of alkoxyl radicals enables selective C(sp3)-C(sp3) bond cleavage and alkynylation/alkenylation reactions with various strained cycloalkanols, and for the first time with linear alcohols.
- Jia, Kunfang,Zhang, Fuyuan,Huang, Hanchu,Chen, Yiyun
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supporting information
p. 1514 - 1517
(2016/02/20)
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- Reactions of gem-Difluorinated Phosphonium Salts Induced by Light
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gem-Difluorinated phosphonium salts, which are readily obtained from aldehydes and difluoromethylene phosphobetaine, can serve as a source of radicals under reductive conditions. An iridium complex or Hantzsch ester was used as a one-electron reducing agent when irradiated with visible light. The fluorinated radicals were trapped with various alkenes, leading to products either via a photoredox cycle (for the iridium catalyst) or via a hydrogen atom transfer (for the Hantzsch ester).
- Panferova, Liubov I.,Tsymbal, Artem V.,Levin, Vitalij V.,Struchkova, Marina I.,Dilman, Alexander D.
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supporting information
p. 996 - 999
(2016/03/15)
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- Synthesis method of 2-(1-hydroxy-4-keto-2,5-cyclohexadiene)-pyran-4-ketone
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The invention discloses a synthesis method of 2-(1-hydroxy-4-keto-2,5-cyclohexadiene)-pyran-4-ketone. The method comprises the steps that 1, on the condition of nitrogen protection and alkali existence, methoxy acetophenone is subjected to siloxane protec
- -
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Paragraph 0008; 0029; 0030; 0050; 0051
(2017/11/01)
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- Halogenative difluorohomologation of ketones
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A method for the difluorohomologation of ketones accompanied by halogenation of a C-H bond is described. The reaction involves silylation, difluorocarbene addition using Me3SiCF2Br activated by a bromide ion, and halogenation of intermediate cyclopropanes with N-bromo- or N-iodosuccinimide. The whole process is performed without isolation of intermediates. The resulting α,α-difluoro-β-halo-substituted ketones can be readily converted into fluorine containing pyrazole derivatives and oxetanes.
- Fedorov, Oleg V.,Kosobokov, Mikhail D.,Levin, Vitalij V.,Struchkova, Marina I.,Dilman, Alexander D.
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p. 5870 - 5876
(2015/06/16)
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- Difluorohomologation of ketones
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A method for the homologation of ketones with the CF2 fragment is described. The reaction involves silylation, room-temperature difluorocyclopropanation of silyl enol ethers, and selective ring opening of cyclopropanes under acidic conditions. The whole three-step sequence is conveniently performed in a one-pot mode.
- Kosobokov, Mikhail D.,Levin, Vitalij V.,Struchkova, Marina I.,Dilman, Alexander D.
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supporting information
p. 760 - 763
(2015/03/05)
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- Iron- or silver-catalyzed oxidative fluorination of cyclopropanols for the synthesis of β-fluoroketones
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The FeIII- or AgI-catalyzed oxidative fluorination of cyclopropanols via radical rearrangement is disclosed. This process features a straightforward and highly effective protocol for the site-specific synthesis of β-fluoroketones and represents an expedient method for the synthesis of γ-, δ- and ε-fluoroketones. Notably, this reaction proceeds at room temperature and tolerates a diverse array of cyclopropanols.
- Ren, Shichao,Feng, Chao,Loh, Teck-Peng
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supporting information
p. 5105 - 5109
(2015/05/13)
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- Umpolung Strategy for Synthesis of β-Ketonitriles through Hypervalent Iodine-Promoted Cyanation of Silyl Enol Ethers
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An efficient method to synthesize β-ketonitriles from silyl enol ethers by an umploung hypervalent iodine(III)-CN species generated in situ from PhIO/BF3·Et2O/TMSCN has been developed for the first time. This method can be applied to structurally diverse aromatic and aliphatic substrates and further extended to preparation of bioactive compounds like 5-aminopyrazole and 5-aminoisoxazole.
- Shen, Hang,Li, Jiaqiang,Liu, Qing,Pan, Jing,Huang, Ruofeng,Xiong, Yan
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p. 7212 - 7218
(2015/07/28)
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- Iridium-catalyzed enantioselective allylation of silyl enol ethers derived from ketones and α,β-unsaturated ketones
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The unified Ir-catalyzed enantioselective allylic substitution reactions of silyl enol ethers derived from ketones and α,β-unsaturated ketones with branched, racemic allylic alcohols are described. This transformation is catalyzed by the Carreira system and proceeds without fluoride, and with high ee and b:l ratio. The synthetic utility of this method was illustrated by the concise enantioselective total synthesis of marine natural products calyxolane A, B and by the assignment of the absolute configuration of calyxolane A.
- Liang, Xiao,Wei, Kun,Yang, Yu-Rong
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supporting information
p. 17471 - 17474
(2015/12/09)
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- Activity of antifungal organobismuth(III) compounds derived from alkyl aryl Ketones against S. cerevisiae: Comparison with a heterocyclic bismuth scaffold consisting of a diphenyl sulfone
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A series of hypervalent organobismuth(III) compounds derived from alkyl aryl ketones [XBi(5-R′C6H3-2-COR)(Ar)] was synthesized to investigate the effect of the compounds' structural features on their antifungal activity against the yeast Saccharomyces cerevisiae. In contrast to bismuth heterocycles [XBi(5-RC6H3-2-SO 2C6H4-1′-)] derived from diphenyl sulfones, a systematic quantitative structure-activity relationship study was possible. The activity depended on the Ar group and increased for heavier X atoms, whereas lengthening the alkyl chain (R) or introducing a substituent (R′) reduced the activity. IBi(C6H4-2-COCH 3)(4-FC6H4) was the most active. Its activity was superior to that of the related acyclic analogues ClBi[C6H 4-2-CH2N(CH3)2](Ar) and ClBi(C 6H4-2-SO2 tert-Bu)(Ar) and also comparable to that of heterocyclic ClBi(C6H4-2-SO2C 6H4-1′-), which was the most active compound in our previous studies. Density function theory calculations suggested that hypervalent bismuthanes undergo nucleophilic addition with a biomolecule at the bismuth atom to give an intermediate ate complex. For higher antifungal activity, adjusting the lipophilicity-hydrophilicity balance, modeling the three-dimensional molecular structure around the bismuth atom, and stabilizing the ate complex appear to be more important than tuning the Lewis acidity at the bismuth atom.
- Murafuji, Toshihiro,Tomura, Mai,Ishiguro, Katsuya,Miyakawa, Isamu
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p. 11077 - 11095
(2014/10/15)
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- Lewis acid catalyzed enlargement of cyclic β-alkoxyenals and one-pot synthesis of polyfunctional enoxysilanes derived from aucubin with trimethylsilyldiazomethane
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Pyrane to oxepane in one step: Highly regio- and stereoselective homologations dependent on the nature of carbonyl function and catalysts have been observed during the formation of enoxysilanes (see scheme). Trimethylsilyl trifluoromethanesulfonate (TMSOT
- Lemus, Christelle,Poleschak, Marko,Gailly, Sophie,Desage-El Murr, Marine,Koch, Michel,Deguin, Brigitte
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supporting information
p. 4686 - 4690
(2013/05/22)
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- Simplification of antitumoral phenanthroindolizidine alkaloids: Short synthesis of cytotoxic indolizidinone and pyrrolidine analogs
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Hydroxylated seco-analogs of cytotoxic phenanthroindolizidine alkaloids were prepared in good yields from inexpensive 4-hydroxyproline derivatives, in just two steps. Thus, a sequential oxidative radical scission - oxidation was used for the direct conversion of the proline derivative into a 2-(2-aryl-oxoethyl) pyrrolidine with a variety of aryl and heteroaryl groups. The 4R-stereogenic center allowed ready isomer separation, and stereocontrol in the introduction of new chains (interestingly, the 2,4-cis isomers predominated). In the second step, a cyclization reaction afforded alkaloid analogs with an indolizidinone core; a partial isomerization took place but the isomers were readily purifi ed. Then the cytotoxic activity of the bicyclic indolizidinones and the simpler pyrrolidine derivatives was compared against tumorogenic human neuronal SHSY-5Y and breast cancer MCF7 cells. All the biphenyl derivatives displayed a potent activity (one derivative caused >80% cell death in both tumor lines at micromolar dosis), being comparable in the pyrrolidine and indolizidinone series.
- Miguélez, Javier,Boto, Alicia,Marín, Raquel,Díaz, Mario
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p. 540 - 554
(2013/10/01)
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- Stereoselective conversion of sugar derivatives into C-nucleosides
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A two-step process for the transformation of readily available carbohydrate derivatives into acyclic C-nucleosides is described. The carbohydrate undergoes a scission process that is followed by the addition of aryl ketone derivatives, allowing the introduction of a variety of aryl rings. The resulting acyclic C-nucleosides are transformed into 2-deoxy cyclic pyranosides in good yield and excellent stereoselectivity.
- Miguelez, Javier,Batchu, Venkateswara Rao,Boto, Alicia
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p. 7652 - 7658
(2012/11/07)
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- Synthesis of (Z)-Trisubstituted olefins by decarboxylative Grob-Type fragmentations: Epothilone D, discodermolide, and peloruside A
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Methyl-branched (Z)-trisubstituted olefins are found in many polyketides with interesting biological activity, such as epothilone D (1), discodermolide (3), and peloruside A (2). Despite the employment of numerous different strategies, this motif has often been the weak point in total synthesis. Thus, we present a novel hydroxideinduced Grob-type fragmentation as an easy access to trisubstituted olefins. In our case, β-mesyloxy δ-lactones with three stereogenic centers were chosen whose fragmentation underlies a high stereoelectronic control. Major challenges in the syntheses were the instailation of quaternary stereocenters, achieved by enzymatic desymmetrization of meso-diesters and by aluminiumpromoted stereoselective rearrangement of chiral epoxides, respectively. Different aldol strategies were developed for the formation of the fragmentation precursors. Additionally a short survey about nucleophilic additions to aldehydes with quaternary α-centers is presented.
- Prantz, Kathrin,Mulzer, Johann
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supporting information; experimental part
p. 485 - 506
(2010/06/14)
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- ScIII-Doped zeolites as new heterogeneous catalysts: mukaiyama aldol reaction
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ScIII-doped solids based on zeolite materials have been investigated for the first time as catalysts in organic synthesis. Sc III-USY zeolite proved to be a novel and very efficient heterogeneous catalyst for the Mukaiyama aldol reaction. This easy-to-prepare catalyst exhibited wide scope and compatibility with functional groups and is very simple to use, easy to remove (by simple filtration), and is recyclable (up to three times without loss of activity).
- Olmos, Andrea,Alix, Aurelien,Sommer, Jean,Pale, Patrick
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supporting information; experimental part
p. 11229 - 11234
(2010/04/28)
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- Electrophilic and nucleophilic side chain fluorination of para-substituted acetophenones
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para-Substituted α-fluoroacetophenones have been synthesised by three different routes. Electrophilic fluorination of trimethylsilyl enol ethers of acetophenones using Selectfluor (F-TEDA-BF4, 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis-(tetrafluoroborate)) gave high to moderate yield depending on the electronic properties of the substituents. F-TEDA-BF4 mediated fluorination of acetophenones in methanol resulted in a mixture of α-fluoroacetophenones and the corresponding 2-fluoro-1,1-dimethyl acetals. The dimethyl acetals were hydrolysed using trifluoroacetic acid in water to maximise the yield of the product. Nucleophilic fluorination of α-bromoacetophenones using tetrabutylammonium hydrogen bifluoride (TBABF) led to moderate yield when having electron-donating substituents, whereas low yields were experienced when more electron-withdrawing substituents were introduced.
- Fuglseth, Erik,Thvedt, Thor H?kon Krane,M?ll, Maria F?rde,Hoff, B?rd Helge
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p. 7318 - 7323
(2008/12/21)
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- Short and efficient synthesis of rubrolide E
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Short and efficient synthesis of rubrolide E from commercially available 4-methoxyacetophenone, employing ring-closing metathesis, Knoevenagel condensation, and Reformatsky reactions, are the key steps are described. Copyright Taylor & Francis Group, LLC.
- Chavan, Subhash P.,Pathak, Ashok B.,Pandey, Ankur,Kalkote, Uttam R.
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p. 4253 - 4263
(2008/03/13)
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- Benzoic acid ester compounds, compositions, uses and methods related thereto
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Benzoic acid ester compounds of formula (I): wherein R and R1-R5 are as defined in the description, methods for producing them and use thereof in cosmetic, pharmaceutical, personal care and industrial preparations as sunscreens based on photochemical precursor properties of ultraviolet absorbers.
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Page/Page column 14
(2010/11/23)
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- Diastereoselective synthesis of five- and seven-membered rings by [2+2+1], [3+2], [3+2+2], and [4+3] carbocyclization reactions of β-substituted (alkenyl)(methoxy)carbene complexes with methyl ketone lithium enolates
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β-Substituted alkenylcarbene complexes react with methyl ketone lithium etiolates to give different carbocyclization products depending on the structure of the lithium enolate, on the metal of the carbene complex, and on the reaction media. Thus, the reac
- Barluenga, Jose,Alonso, Jorge,Fananas, Francisco J.
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p. 4995 - 5006
(2007/10/03)
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- Optimisation of the allylsilane approach to C-10 deoxo carba analogues of dihydroartemisinin: Synthesis and in vitro antimalarial activity of new, metabolically stable C-10 analogues
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An optimised protocol has been developed for the coupling of dihydroartemisinin benzoate with a range of aromatic allylsilanes to provide a number of new C-10 deoxo derivatives (11a-11g) in yields ranging from 70 to 94%. These compounds were up to ten times more potent than artemisinin in in vitro tests against the chloroquine resistant K1 strain of Plasmodium falciparum. Ferrous mediated degradation of these analogues produces as the main product, a dicarbonyl formate 12, which is not seen when the same reaction is carried out with artemisinin or artemether. This finding may indicate that analogues in this class have a subtly different "antimalarial" mechanism of action.
- O'Neill,Pugh,Stachulski,Ward,Davies,Kevin Park
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p. 2682 - 2689
(2007/10/03)
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- Reactions of trichloromethanesulfonyl chloride and carbon tetrachloride with silyl enol ethers catalyzed by a ruthenium(II) phosphine complex
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The reactions of trichloromethanesulfonyl chloride with trimethylsilyl enol ethers of acetophenones in the presence of a ruthenium(II) phosphine complex gave 1-aryl-3,3-dichloropropen-1-one together with α-chloroacetophenones. The product ratio depended on the substituent on the aromatic ring of the silyl enol ether. The reactions of carbon tetrachloride with the silyl enol ethers under similar conditions afforded 1-aryl-3,3-dichloropropen-1-one in good yield.
- Kamigata, Nobumasa,Udodaira, Kumiko,Yoshikawa, Manabu,Shimizu, Toshio
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- Reactions of sulfonyl chlorides with silyl enol ethers catalysed by a ruthenium(II) phosphine complex: Convenient synthesis of β-keto sulfones
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The reactions of alkane- and arene-sulfonyl chlorides with silyl enol ethers in the presence of a ruthenium(II) phosphine complex are found to give β-keto sulfones in good to high yields.
- Kamigata, Nobumasa,Udodaira, Kumiko,Shimizu, Toshio
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p. 783 - 786
(2007/10/03)
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- Reactions of perfluoroalkanesulfonyl chlorides with silyl enol ethers catalyzed by a ruthenium(II) phosphine complex
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Reactions of trifluoromethane- and tridecafluorohexanesulfonyl chlorides with silyl enol ethers have been investigated in the presence of a ruthenium(II) phosphine complex. Perfluoroalkylation and chlorination occurred depending on the substituent of silyl enol ether; i.e. perfluoroalkylated compound was selectively obtained in the reactions with silyl enol ether possessing an electron-withdrawing group, on the other hand, chlorinated compounds selectively formed in the reaction with a silyl enol ether possessing electron-donating group.
- Kamigata, Nobumasa,Udodaira, Kumiko,Shimizu, Toshio
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p. 155 - 168
(2007/10/03)
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- A Topliss tree analysis of the HIV-protease inhibitory activity of 6- phenyl-4-hydroxy-pyran-2-ones
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In a study of 4-hydroxy-pyran-2-ones as possible inhibitors of HIV protease, a series of compounds were synthesized following the Topliss operational scheme for substitution on a phenyl group at the 6 position of the pyrone. In addition, a number of compounds with polar substituents were made.
- Steinbaugh,Hamilton,Prasad,Para,Tummino,Ferguson,Lunney,Blankley
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p. 1099 - 1104
(2007/10/03)
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- Thermal addition reaction of aroylketene with 1-aryl-1- trimethylsilyloxyethylenes: Aromatic substituent effects of aroylketene and aryltrimethylsilyloxyethylene on their reactivity
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The thermal addition reaction of various aroylketenes (C) generated by the thermolysis of 5-aryldioxofurans (A) to 1-aryl-1-trimethylsilyloxyethylenes gave 1,5-diarylpentane-1,3,5-triones (D) and 2,6-diaryl-4H-pyran-4-ones (E). The introduction of electron withdrawing substituents in the aroylketene and of electron donating substituents facilitated the addition reaction. The observed substituent effects and the reaction mechanism are interpreted in terms of molecular orbital analyses.
- Saitoh,Oyama,Sakurai,Niimura,Hinata,Horiguchi,Toda,Sano
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p. 956 - 966
(2007/10/03)
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- Synthesis and 13C FT NMR spectroscopy of furan-2,3-dione derivatives
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Substituted furan-2,3-diones were obtained by condensation of oxalyl chloride with silyl enol ether of para-substituted acetophenones (R = H, CH3, OCH3, Cl, Br, F), propiophenone, 1-tetralone, 6-methoxytetralone and 1-benzosuberone.The spectroscopic data obtained from IR, UV, 1H and 13C NMR studies are quite similar whichever are the substituents. furan-2,3-dione / 1H and 13C NMR / UV and IR spectra
- Hnach, M.,Aycard, J. P.,Zineddine, H.
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p. 393 - 396
(2007/10/02)
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- Enolate Ions, II. - Convenient Synthesis of 3,4-Dihydro-2,4-dioxo-2H-pyrans and 2-Pyrones. - Enolate Ions as Synthetic Equivalents of 1,3-Dianions. - Crystal and Molecular Structure of Ethyl 6-Ethoxy-3,4-dihydro-3,3-dimethyl-2,4-dioxo-2H-pyran-5-carboxyla
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Reaction of dimethylmalonyl chloride (6a) or cyclic 1,1-dicarbonyl dichlorides 6b-d with two equivalents of lithium enolates 7, 22, and silyl enol ethers 8, respectively, yields 3,4-dihydro-2,4-dioxo-2H-pyrans 10, 24, or spiro compounds 11-13, 25-27.The s
- Saalfrank, Rolf W.,Guendel, Juergen,Rossmann, Guenther,Hanek, Martin,Rost, Walter,et al.
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p. 1175 - 1183
(2007/10/02)
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- Carbon-Carbon Bond Formation Using Hypervalent Iodine Under Lewis Acid Conditions: Scope of the Method for the Synthesis of Butane-1,4-diones
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Hypervalent iodine oxidation of the silyl enol ethers of various acetophenones (2a-g), 2-acetylthiophenes (2i-k), 2-acetylfuran (2l) and 2-acetylbenzofuran (2m) with iodosobenzene-boron trifluoride-diethyl ether results in carbon-carbon coupling to yield the corresponding 1,4-disubstituted butane-1,4-dione (3a-m).Cross coupling (dissimilar coupling) between 4-methoxyacetophenone silyl enol ether (2c) and 4-nitroacetophenone silyl enol ether (2e) affords 1-(4-methoxyphenyl)-4-(4-nitrophenyl)butane-1,4-dione (27percent); the other minor products (3c) (18percent) and (3e) (15percent) resulting from similar coupling in this reaction.The sterically hindered aliphatic silyl enol ether (2h) obtained from pinacolone also undergoes smooth coupling whereas other aliphatic ketones do not.This method is likewise unsuccessful in case of nitrogen-containing heterocycles, viz. 2-,3-,4-acetylpyridine silyl enol ethers and tropinone silyl enol ether.
- Moriarty, Robert,Prakash, Om,Duncan, Michael P.
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p. 559 - 562
(2007/10/02)
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- SYNTHESIS OF 1,4-DIKETONES BY THE COUPLING REACTION OF TRIMETHYLSILYL ENOL ETHERS WITH LEAD TETRAACETATE
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Synthesis of 1,4-diketones in good yields was achieved by the coupling reaction of the trimethylsilyl enol ethers of acetophenone,thiophene or furan with lead tetraacetate in dry dichloromethane and tetrahydrofuran at -78 degC.
- Moriarty, Robert M.,Penmasta, Raju,Prakash, Indra
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p. 873 - 876
(2007/10/02)
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