- Triazene-Activated Donor-Acceptor Cyclopropanes: Ring-Opening and (3 + 2) Annulation Reactions
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Donor-acceptor cyclopropanes substituted with 3,3-dialkyltriazenyl groups are described herein. The strong electron-donating character of the triazene renders the cyclopropanes highly reactive, allowing for catalyst-free ring-opening reactions with methanol and tetracyanoethylene under mild conditions. The triazene-substituted cyclopropanes could also be used as substrates in Lewis acid catalyzed (3 + 2) annulations with silyl enol ethers.
- Dong, Zhaowen,Fadaei-Tirani, Farzaneh,Le Du, Eliott,Muriel, Bastian,Scopelliti, Rosario,Severin, Kay,Suleymanov, Abdusalom A.,Waser, Jér?me
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- A Convenient Regioselective Synthesis of Mannich Bases
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A new, convenient regioselective process for aminomethylation of ketones is reported, involving the in situ formation of silyl enol ethers and iminium salts.
- Rochin, C.,Babot, O.,Dunogues, J.,Duboudin, F.
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- THE REACTION OF CHROMYL CHLORIDE AND O-SILYLATED ENOLATES: A NOVEL REGIOSPECIFIC ROUTE TO α-HYDROXY KETONES.
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Chromyl chloride reacts regiospecifically with O-silylated enolates to form α-hydroxy ketones.
- Lee, Thomas V.,Toczek, Judy
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- A practical method for the preparation of trimethylsilyl enol ethers
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In the mixed system of chlorotrimethylsilane/triethyl amine/N,N-dimethylformamide/potassium iodide/petroleum ether, aldehydes or ketones are silylated to silyl enol ethers at room temperature. The N,N-dimethylformamide/potassium iodide layer can be used as circulating liquor for many times. The yields are high.
- Lin, Ji-Mao,Liu, Ben-Sheng
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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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- Use of 1,8-Diazabicycloundec-7-ene in Preparation of Trimethylsilyl Enol Ethers and Trimethylsilylacetylenes
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Trimethylsilyl enol ethers were prepared by using a combination of chlorotrimethylsilane and 1,8-diazabicycloundec-7-ene in good yields.Trimethylsilylation of acetylenes was also achieved with the same reagents in the presence of silver salt as catalyst.
- Taniguchi, Yoshiyuki,Inanaga, Junji,Yamaguchi, Masaru
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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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- Changing course with an additive: A striking example of the effect of TMSCl on lithium amide reactivity
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When a solution of diethyl maleate and acetophenone is added to a cooled (-78°C) solution of a lithium amide the maleate derivative 3 is given in good yield. Pre-treatment of the lithium amide with TMSCl alters the course of this reaction dramatically. With half an equivalent of this additive the Michael adduct 4 is given in 62% yield while employing three equivalents leads to the silyl enol ether 5 in >85% yield.
- Harrowven, David C.,Poon, Hon Suen
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- Palladium Catalyzed Reaction of Trimethylsilyltributyltin with α-Halo Ketones. Preparation of Enol Silyl Ethers
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The reaction of trimethylsilyltributyltin with α-halo ketone in the presence of a catalytic amount of palladium chloride plus twice molar amounts of trimethyl phosphite gave enol silyl ethers in good yields.
- Kosugi, Masanori,Ohya, Takao,Migita, Toshihiko
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- Addition reaction of imidazoles and thiazoles with silyl enol ethers in the presence of alkyl chloroformate
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Silyl enol ethers and ketene silyl acetals reacted with imidazole, thiazole, and their benzo derivatives in the presence of an alkyl chloroformate to give 2-substituted imidazolines and thiazolines in good yields via the intermediacy of unstable N-acylated quaternary salts of azoles. In addition, it was found that silyl enol ethers formed in situ were also useful for the reaction to afford the adducts only by simple sequential addition of five commercially available reagents. (C) 2000 Elsevier Science Ltd.
- Itoh, Takashi,Miyazaki, Michiko,Nagata, Kazuhiro,Ohsawa, Akio
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- THE MANNICH REACTION OF CARBONYL COMPOUNDS VIA SILYL ENOL ETHERS BY A COMBINATION OF CHLOROIODOMETHANE AND N,N,N',N'-TETRAMETHYLDIAMINOMETHANE
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The Mannich dimethylaminomethylation of carbonyl compounds is conveniently carried out via trimethylsilyl enol ethers by a combination of chloroiodomethane and N,N,N',N'-tetramethyldiaminomethane in DMSO or DMF as the solvent at ambient temperature.
- Miyano, Sotaro,Hokari, Hiroshi,Mori, Akira,Hashimoto, Harukichi
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- Silylation of Relatively Acidic Compounds with Alkyl Trimethylsilylacetates
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Silylation of ketones, alcohols, alkanetiols, phenols, and carboxylic acids with alkyl trimethylsilylacetates has been described from synthetic and mechanistic points of view.
- Nakamura, Eiichi,Hashimoto, Koichi,Kuwajima, Isao
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- Regioselective one-pot synthesis of 2,3-diaryl-2H-1-benzopyrans via Br?nsted acid-catalyzed [4+2] cycloaddition of salicylaldehydes with diarylacetylenes
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A regioselective one-pot synthesis of 2,3-diaryl-2H-1-benzopyrans from easily available various diarylacetylenes and salicylaldehydes via Br?nsted acid-catalyzed [4+2] cycloaddition has been developed. High regioselectivity was observed in the reaction to afford 2-(electron-rich aryl)-3-(electron-poor aryl)-2H-1-benzopyrans in good yields. The present reaction provides versatile access to functionalized 2,3-diaryl-2H-1-benzopyrans, which would be useful as key intermediates for the synthesis of biologically and photochemically active molecules.
- Tanaka, Kenta,Shigematsu, Yosuke,Sukekawa, Mayumi,Hoshino, Yujiro,Honda, Kiyoshi
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- Palladium Catalyzed Coupling Reaction of α-Bromo Ketones with Hexabutylditin
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Palladium-catalyzed reaction of α-bromo ketones with hexabutylditin in the presence of trimethylsilyl chloride gave enol trimethylsilyl ether in moderate to good yields.
- Kosugi, Masanori,Koshiba, Mamoru,Sano, Hiroshi,Migita, Toshihiko
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- Preparation of a New, Highly Reactive Form of Iron(0) and Its Use in Deprotonation of Carbonyl Compounds
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A new, highly reactive form of zerovalent iron, prepared from the reaction of methylmagnesium bromide and ferric chloride, has been found to deprotonate cyclic unsymmetrical ketones in the presence of trimethylsilyl chloride to give thermodynamic (more substituted) silyl enol ethers regiospecifically.
- Krafft, Marie E.,Holton, Robert A.
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- Latent Nucleophilic Carbenes
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Using DFT and ab initio calculations, we demonstrate that noncyclic formamidines can undergo thermal rearrangement into their isomeric aminocarbenes under rather mild conditions. We synthesized the silylformamidine, for which the lowest activation energy in this process was predicted. Experimental studies proved it to serve as a very reactive nucleophilic carbene. The reactions with acetylenes, benzenes, and trifluoromethane proceeded via insertion into sp, sp2, and spCH bonds. The carbene also reacted with the functional groups, such as CHO, COR, and CN at double or triple bonds, displaying high mobility of the trimethylsilyl group. The obtained silylformamidine can be considered as a latent nucleophilic carbene. It can be prepared in bulk quantities, stored, and used when the need arises. Calculation results predict similar behavior for some other silylated formamidines and related compounds.
- Marchenko, Anatoliy,Koidan, Georgyi,Hurieva, Anastasiya,Shvydenko, Kostiantyn,Rozhenko, Alexander B.,Rusanov, Eduard B.,Kyrylchuk, Andrii A.,Kostyuk, Aleksandr
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p. 373 - 385
(2021/12/27)
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- Electrochemical α-Arylation of Ketones via Anodic Oxidation of in Situ Generated Silyl Enol Ethers
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An electrochemical procedure for the α-arylation of ketones has been developed. The method is based on the generation and one-pot anodic oxidation of silyl enol ethers in the presence of the arene. This strategy avoids isolation of the silyl enol intermediate and the utilization of external supporting electrolytes. Intermolecular arylations, which had not been reported so far, are possible when electron-rich arenes are utilized as coupling partners. The method has been demonstrated for a wide variety of aryl ketones and activated arenes, with moderate to good yields (up to 69%) obtained. Mechanistic insights and a theoretical rationale that explains the ketone α-arylation versus dimerization selectivity are also presented.
- Jud, Wolfgang,Sommer, Florian,Kappe, C. Oliver,Cantillo, David
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p. 16026 - 16034
(2021/08/24)
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- Boron Trifluoride-Mediated Cycloaddition of 3-Bromotetrazine and Silyl Enol Ethers: Synthesis of 3-Bromo-pyridazines
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Pyridazines are important scaffolds for medicinal chemistry or crop protection agents, yet the selective preparation of 3-bromo-pyridazines with high regiocontrol remains difficult. We achieved the Lewis acid-mediated inverse electron demand Diels-Alder reaction between 3-monosubstituted s-tetrazine and silyl enol ethers and obtained functionalized pyridazines. In the case of 1-monosubstituted silyl enol ethers, exclusive regioselectivity was observed. Downstream functionalization of the resulting 3-bromo-pyridazines was demonstrated utilizing several cross-coupling protocols to synthesize 3,4-disubstituted pyridazines with excellent control over the substitution pattern.
- Schnell, Simon D.,González, Jorge A.,Sklyaruk, Jan,Linden, Anthony,Gademann, Karl
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p. 12008 - 12023
(2021/08/24)
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- Sequential Photocatalytic Reactions for the Diastereoselective Synthesis of Cyclobutane Scaffolds
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The synthesis of densely functionalized cyclobutanes containing all-carbon quaternary stereocenters in high regio- and diastereoselectivity remains synthetically challenging. Herein, we show that this can be achieved by using a sequential photocatalysis strategy, wherein 3-chloromaleimides undergo triplet sensitized [2 + 2] photocycloadditions with alkynes or alkenes followed by photoredox-catalyzed dechlorinative C-C bond forming reactions to install quaternary stereocenters. This allows the rapid assembly of structurally complex and sterically congested 3-azabicyclo[3.2.0]heptane scaffolds from readily available starting materials.
- Aggarwal, Varinder K.,Booker-Milburn, Kevin I.,Deeprose, Mark J.,Lowe, Martin,Noble, Adam
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supporting information
(2021/12/17)
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- 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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- PESTICIDALLY ACTIVE DIAZINE-AMIDE COMPOUNDS
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Compounds of formula I (l) wherein the substituents are as defined in claim 1, and the agrochemically acceptable salts, stereoisomers, enantiomers, tautomers and N-oxides of those compounds, can be used as insecticides.
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Page/Page column 90
(2020/10/20)
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- Photocatalytic Vicinal Aminopyridylation of Methyl Ketones by a Double Umpolung Strategy
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A photocatalytic double umpolung strategy for the vicinal aminopyridylation of ketones was developed using pyridinium N?N ylides. The inversion of the polarity of the pyridinium N?N ylides by single-electron oxidation successfully enables radical-mediated 1,3-dipolar cycloadditions with enolsilanes formed in situ from ketones, followed by homolytic cleavage of the N?N bond. Intriguingly, the nucleophilic amino and electrophilic pyridyl groups in the ylides can be installed at the nucleophilic α-position and electrophilic carbonyl carbon, respectively, which are typically inaccessible by their innate polarity-driven reactivity. This method accommodates a broad scope, and the utility was further demonstrated by the late-stage functionalization of complex biorelevant molecules. Moreover, the strategy can be successfully applied to enamides.
- Choi, Wonjun,Hong, Sungwoo,Im, Honggu
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supporting information
p. 17511 - 17516
(2020/08/14)
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- Pd-catalyzed imine-directed intramolecular C–N bond formation through C(sp3)–H activation: An efficient approach to multisubstituted pyrroles
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An atom-economic approach to synthesize 1,2,4-trisubstituted pyrroles through palladium-catalyzed imine-directed intramolecular C(sp3)–H amination reaction has been developed. The imine group acts as a directing group as well as an intramolecular nucleophile for the first time in intramolecular C–N bonds formation reactions.
- Yu, Ting,Zhu, Qiang,Luo, Shuang
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supporting information
(2020/04/08)
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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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- Fluorescence emission material and organic light-emitting device prepared from fluorescence emission material
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The invention discloses a fluorescence emission material and an organic light-emitting device prepared from the fluorescence emission material. A thiophene/furan [2, 3-b] quinoxaline and tricyclic aromatic hydrocarbon fused high-efficiency blue fluorescence and other color light-emitting materials are constructed through molecular design. The luminescent wavelength of the material can be regulatedto 426nm and 457nm, and the absolute fluorescence quantum yield reaches 65% and 82% respectively. The material can provide beneficial supplement for commercial blue light materials.
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Paragraph 0060-0064
(2020/11/05)
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- Autocatalytic Carbonyl Arylation through In Situ Release of Aryl Nucleophiles from N-Aryl-N′-Silyldiazenes
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A method for the catalytic generation of functionalized aryl alkali metals is reported. These highly reactive intermediates are liberated from silyl-protected aryl-substituted diazenes by the action of Lewis basic alkali metal silanolates, resulting in desilylation and loss of N2. Catalytic quantities of these Lewis bases initiate the transfer of the aryl nucleophile from the diazene to carbonyl and carboxyl compounds with superb functional-group tolerance. The aryl alkali metal can be decorated with electrophilic substituents such as methoxycarbonyl or cyano as well as halogen groups. The synthesis of a previously unknown cyclophane-like [4]arene macrocycle from a 1,3-bisdiazene combined with a 1,4-dialdehyde underlines the potential of the approach.
- Chauvier, Clément,Finck, Lucie,Irran, Elisabeth,Oestreich, Martin
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supporting information
p. 12337 - 12341
(2020/03/23)
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- Luminous organic semiconductor framework material as well as applications
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The invention discloses a luminous organic semiconductor framework material as well as applications: by arranging heteroatoms, such as N, O and S, on the same end of an aromatic fused ring, the molecule is induced to generate static dipole moment; then through the intermolecular forces, such as intermolecular hydrogen bonds, dipolar-dipolar interaction and the like, the stacking microstructure ofthe molecule under aggregation state, the luminous performance of the material, emitting color of the material, and carrier transport performance of the material are regulated. The product has excellent luminescence property under aggregation state.
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Paragraph 0060; 0061; 0063-0066
(2019/04/10)
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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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- 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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- A Solvent-Free Reaction for Silyl Enol Ethers Synthesis
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Silyl enol ethers are extremely useful nucleophilic intermediates for chemical transformations because they are synthetically versatile substrates for a wide range of C-C bond-forming reactions. Here, we present a new, mild, and solvent-free procedure for the synthesis of silyl enol ethers that employs a catalytic amount of solid-supported base and an equimolar amount of N, O -(bistrimethylsilyl)acetamide as a silylating agent.
- Morozzi, Chiara,Rosati, Ornelio,Curini, Massimo,Lanari, Daniela
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supporting information
p. 126 - 130
(2017/12/28)
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- FLP-Catalyzed Transfer Hydrogenation of Silyl Enol Ethers
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Herein we report the first catalytic transfer hydrogenation of silyl enol ethers. This metal free approach employs tris(pentafluorophenyl)borane and 2,2,6,6-tetramethylpiperidine (TMP) as a commercially available FLP catalyst system and naturally occurring γ-terpinene as a dihydrogen surrogate. A variety of silyl enol ethers undergo efficient hydrogenation, with the reduced products isolated in excellent yields (29 examples, 82 % average yield).
- Khan, Imtiaz,Reed-Berendt, Benjamin G.,Melen, Rebecca L.,Morrill, Louis C.
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supporting information
p. 12356 - 12359
(2018/09/18)
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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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- 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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- Unprecedented alkylation of silicon enolates with alcohols via carbenium ion formations catalyzed by tin hydroxide-embedded montmorillonite
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The solid acid, tin hydroxide-embedded montmorillonite, catalyzes the unprecedented alkylation of various silicon enolates with primary, secondary and tertiary benzylic alcohols as well as secondary allylic alcohols. The acid catalysis of Sn-Mont was not only higher than that of the other ion-exchanged montmorillonites (M-Mont; M?=?H, Ti, Fe and Al), but also higher than that of the typical homogeneous acid catalysts such as BF3·OEt2, TMSOTf and TfOH.
- Tandiary, Michael Andreas,Asano, Masashi,Hattori, Taiki,Takehira, Satoshi,Masui, Yoichi,Onaka, Makoto
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supporting information
p. 1925 - 1928
(2017/04/27)
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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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- Synthesis of 3-Fluoropyridines via Photoredox-Mediated Coupling of α,α-Difluoro-β-iodoketones with Silyl Enol Ethers
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A method for the synthesis of diversely substituted 3-fluoropyridines from two ketone components is described. The reaction involves photoredox coupling of α,α-difluoro-β-iodoketones with silyl enol ethers catalyzed by fac-Ir(ppy)3 under blue LED irradiation with subsequent one-pot condensation with ammonium acetate. Based on cyclic voltammetry studies, it was determined that α,α-difluoro-β-iodoketones are reduced notably easier compared to 2,2,2-trifluoro-1-iodoethane, which may be ascribed to the influence of the carbonyl group.
- Scherbinina, Sofya I.,Fedorov, Oleg V.,Levin, Vitalij V.,Kokorekin, Vladimir A.,Struchkova, Marina I.,Dilman, Alexander D.
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p. 12967 - 12974
(2017/12/15)
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- Regioselective synthesis of substituted cyclopenta[l]phenanthrenes
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A simple and efficient synthesis of cyclopenta[l]phenanthrenes from substituted acetophenones provides access to polycyclic aromatics with a variety of substitution patterns. The synthesis requires only three steps from a silyl enol ether: a Mukaiyama aldol reaction followed by McMurry coupling and then Mallory photocyclooxidation to give the target phenanthrenes. Photocyclization conditions have been found that give regioselective formation of 2,7-phenanthrenes from bis(meta-substituted) stilbenes.
- Connors, David M.,Goroff, Nancy S.
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supporting information
p. 4262 - 4265
(2016/09/09)
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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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- Chemo- and regioselective preparation of zinc enolate from thiol esters by palladium catalyzed cross-coupling reaction
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The palladium catalyzed cross-coupling reaction of thiol esters with bis(iodozincio)methane or 1,1-bis(iodozincio)ethane gave Reformatsky-type enolates. They can react with some electrophiles to give the corresponding adducts and were also trapped by silylation reagents to afford silyl enol ethers. As the method applicable to the thiol ester carrying ketone moiety, it afforded zinc enolates carrying ketone in the same molecule.
- Haraguchi, Ryosuke,Ikeda, Zenichi,Ooguri, Akihiro,Matsubara, Seijiro
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p. 8830 - 8837
(2015/10/20)
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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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- Photocatalytic ?±-oxyamination of stable enolates, silyl enol ethers, and 2-oxoalkane phosphonic esters
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Fast ?±-oxyamination of stable enolates, silyl enol ethers, and in situ deprotonated dialkyl 2-oxoalkane phosphonates and diphenyl-2-oxoalkyl phosphine oxides was performed in the presence of [Ru(bpy)3]2+ (bpy = 2,2a?2-bipyridyl) as a photocatalyst, 2,2,6,6-tetramethylpiperidine nitroxide (TEMPO), and visible light. The key step was the light-induced one-electron oxidation of TEMPO into the 2,2,6,6-tetramethylpiperidine- 1-oxoammonium ion, which was nucleophilically attacked to yield ?±-functionalized carbonyl compounds. The reaction time was significantly reduced by the use of the microreactor flow technique.
- Schroll, Peter,K??nig, Burkhard
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supporting information
p. 309 - 313
(2015/03/03)
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- Chiral Br?nsted Acid as a True Catalyst: Asymmetric Mukaiyama Aldol and Hosomi-Sakurai Allylation Reactions
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Highly diastereo- and enantioselective Mukaiyama aldol reaction catalyzed by a new chiral Br?nsted acid, N-(perfluorooctanesulfonyl)thiophosphoramide, is described. The perfluorooctyl substituent on the sulfonyl group of the catalyst plays an essential role in the stereoselection. The catalyst also allows the asymmetric Hosomi-Sakurai allylation, which has been considerably challenging due to the low reactivity of allylsilanes. 29Si and 31P NMR monitoring reveals the characteristic feature of the thiophosphoramide catalyst, acting as a strong Br?nsted acid even in the presence of excess silyl nucleophiles, which cannot be found in other related phosphoric acid analogues.
- Sai, Masahiro,Yamamoto, Hisashi
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supporting information
p. 7091 - 7094
(2015/06/25)
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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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- The mukaiyama aldol reactions for congested ketones catalyzed by solid acid of tin(IV) ion-exchanged montmorillonite
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Tin(IV) ion-exchanged montmorillonite (Sn-Mont) was found to be an excellent solid acid catalyst for the Mukaiyama aldol reactions of congested ketones with silicon enolates from ketones as well as esters. It was disclosed that Sn-Mont was far more active than other metal ion-or proton-exchanged montmorillonites and typical homogeneous acid catalysts such as TMSOTf and BF3?OEt2.
- Takehira, Satoshi,Masui, Yoichi,Onaka, Makoto
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supporting information
p. 498 - 500
(2014/04/17)
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- A study of base-catalyzed aldol reaction of trimethylsilyl enolates
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Mukaiyama-type aldol reaction of trimethylsilyl enolates with aldehydes in the presence of a base is a complicated reaction. It usually results in various products determined by the nature of base and reaction medium. The present study has been undertaken to understand these factors and design new Lewis base catalysts to optimize the yield of desired aldol product. It has been shown that mild Bronsted base with inbuilt hydrogen bonding sites are efficient catalysts for the reactions involving trimethylsilyl enolates. Based on the observed results, a mechanism is proposed to explain the reaction outcome.
- Sutar,Joshi
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p. 1553 - 1560
(2015/02/02)
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- Aerobic oxidative desymmetrization of meso-diols with bifunctional amidoiridium catalysts bearing chiral N-sulfonyldiamine ligands
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Asymmetric aerobic oxidation of a range of meso- and prochiral diols with chiral bifunctional Ir catalysts is described. A high level of chiral discrimination ability of Cpa? -Ir complexes derived from (S,S)-1,2-diphenylethylenediamine was successfully demonstrated by desymmetrization of secondary benzylic diols such as cis-indan-1,3-diol and cis-1,4-diphenylbutane-1,4-diol, providing the corresponding (R)-hydroxyl ketones with excellent chemo- and enantioselectivities. Enantiotopic group discrimination in oxidation of symmetrical primary 1,4- and 1,5-diols gave rise to chiral lactones with moderate ees under similar aerobic conditions.
- Moritani, Junki,Hasegawa, Yasuharu,Kayaki, Yoshihito,Ikariya, Takao
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supporting information
p. 1188 - 1191
(2014/02/14)
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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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- A highly enantioselective hydrogenation of silyl enol ethers catalyzed by chiral frustrated lewis pairs
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Using a simple combination of tri-tert-butylphosphine and chiral borane generated in situ by the hydroboration of chiral diene with HB(C 6F5)2 as a frustrated Lewis pair catalyst, a highly enantioselective metal-free hydrogenation of silyl enol ethers was successfully realized to furnish a variety of optically active secondary alcohols in 93-99% yields with 88->99% ees.
- Wei, Simin,Du, Haifeng
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supporting information
p. 12261 - 12264
(2014/10/16)
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- Chemoselective silyl transfer in the Mukaiyama aldol reaction promoted by super silyl Lewis acid
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In the silyl Lewis acid-promoted Mukaiyama aldol reaction, the steric and electronic properties of the silyl group on the silyl Lewis acid influence the reaction mechanism and product distribution. When super silyl triflates such as (TMS)3SiOTf and (TES)3SiOTf are used as Lewis acids, the silyl group of the silyl enol ether chemoselectively transfers to the product. The mechanistic details have been investigated using density functional theory (DFT) calculations.
- Sai, Masahiro,Akakura, Matsujiro,Yamamoto, Hisashi
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supporting information
p. 15206 - 15208
(2015/01/08)
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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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- Mukaiyama aldol reaction of trimethylsilyl enolate with aldehyde catalyzed by CuI
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Cuprous iodide has been found to be a very effective catalyst for Mukaiyama aldol reaction of trimethylsilyl ketene acetal with aldehydes. The new catalytic system promotes efficiently the Mukaiyama aldol reaction in DMF to produce corresponding β-hydroxy carbonyl compounds in high yield.
- Kalita, Hima Rani,Borah, Arun Jyoti,Phukan, Prodeep
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p. 289 - 292
(2013/05/22)
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- Enantioselective Mukaiyama-Michael reaction of silyl enol ethers to 2-enoylpyridine N-oxides catalyzed by copper-bis(oxazoline) complex
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A catalytic enantioselective Mukaiyama-Michael reaction of 2-enoylpyridine N-oxides has been developed using a simple bis(oxazoline)-copper complex. A variety of silyl enol ethers undergo smooth Michael addition with 2-enoylpyridine N-oxides to furnish the corresponding Michael adducts in high yields with high enantioselectivities (up to 97% ee).
- Georgea, Jimil,Reddy, Basi V. Subba
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supporting information
p. 383 - 388
(2013/05/08)
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