- The Conformational Analysis of 1-p-Tolyl-2-phenyl-1-propanols, 1-p-Tolyl-2-phenylethanol, and 1-p-Tolyl-2-phenyl-1-propanone by Means of NMR Spectroscopy
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The conformations of the diastereomers of 1-p-tolyl-2-phenyl-1-propanols, 1-p-tolyl-2-phenylethanol (4), and 1-p-tolyl-2-phenyl-1-propanone (5) were studied by means of NMR spectroscopy, mostly with the aid of the computer-simulation of the lanthanoid-induced shifts.It has been suggested that the rotamers in which the tolyl group lies close to the phenyl group are preferred in the conformational equilibria of (RS/SR)-3, 4, and 5.For (RR/SS)-3, the most stable rotamer (in CDCl3) has been suggested to have the tolyl group anti to the phenyl group and gauche to the methyl group.The results have been discussed in view of the general occurrence of the folded conformation.
- Kunieda, Norio,Endo, Hiroko,Hirota, Minoru,Kodama, Yoshio,Nishio, Motohiro
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- Selective α-Methylation of Aryl Ketones Using Quaternary Ammonium Salts as Solid Methylating Agents
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We describe the use of phenyl trimethylammonium iodide (PhMe3NI) as an alternative methylating agent for introducing a CH3group in α-position to a carbonyl group. Compared to conventional methylating agents, quaternary ammonium salts have the advantages of being nonvolatile, noncancerogenic, and easy-to-handle solids. This regioselective method is characterized by ease of operational setup, use of anisole as green solvent, and yields up to 85%.
- Templ, Johanna,Schnürch, Michael
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p. 4305 - 4315
(2022/03/16)
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- Enantioselective α-Arylation of Ketones via a Novel Cu(I)-Bis(phosphine) Dioxide Catalytic System
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A novel catalytic system based on copper(I) and chiral bis(phosphine) dioxides is described. This allows the arylation of silyl enol ethers to access enolizable α-arylated ketones in good yields and enantiomeric excess up to 95%. Noncyclic ketones are amenable substrates with this method, which complements other approaches based on palladium catalysis. Optimization of the ligand structure is accomplished via rational design driven by correlation analysis. Preliminary mechanistic hypotheses are also evaluated in order to identify the role of chiral bis(phosphine) dioxides.
- Escudero-Casao, Margarita,Licini, Giulia,Orlandi, Manuel
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supporting information
p. 3289 - 3294
(2021/04/07)
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- Blue Light Promoted Difluoroalkylation of Aryl Ketones: Synthesis of Quaternary Alkyl Difluorides and Tetrasubstituted Monofluoroalkenes
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A facile and cost-effective method for the preparation of fluoroalkylated compounds has been described by the direct photoexcitation of halofluoroalkanes with blue light absorptivity, enabling the difluoroalkylation of aryl ketones. The methodology has provided an efficient, mild, and catalyst-free synthetic method for quaternary difluoroalkylated arenes and tetrasubstituted monofluoroalkenes.
- Li, Kangkui,Chen, Jingchao,Yang, Chunhui,Zhang, Keyang,Pan, Chunxiang,Fan, Baomin,Fan, Baomin
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supporting information
p. 4261 - 4265
(2020/06/04)
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- N-Heterocyclic carbene-palladacyclic complexes: synthesis, characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides
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N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01 mol%).
- Liu, Feng,Hu, Yuan-Yuan,Li, Di,Zhou, Quan,Lu, Jian-Mei
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p. 5683 - 5690
(2018/08/24)
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- One-pot synthesis of α,α-disubstituted Aryl-1-ethanones via the Wittig-Horner reaction
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A one-pot methodology for the synthesis of α,α-disubstituted aryl-1-ethanones via the Wittig-Horner reaction has been developed and described in this manuscript. Both aryl/alkyl and dialkyl α-branched arylethanone were obtained in high yields (up to 96%) without the use of any metal catalysts. A total of 14 α,α-disubstituted arylethanone derivatives were synthesized based on this simple method that easily converts the carbonyl carbon (sp2) into the sp3 carbon. This versatile method is expected to further promote the use of substituted ketones as synthetic building blocks to construct a variety of α-branched aryl ketones.
- Yang, Yunxia,Wang, Le,Chen, Yuan,Dai, Yiru,Sun, Zhihua
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p. 121 - 126
(2018/01/04)
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- Intermolecular Markovnikov-Selective Hydroacylation of Olefins Catalyzed by a Cationic Ruthenium-Hydride Complex
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The cationic Ru-H complex was found to be an effective catalyst for the intermolecular hydroacylation of aryl-substituted olefins with aldehydes to form branched ketone products. The preliminary kinetic and spectroscopic studies elucidated a ruthenium-acy
- Kim, Junghwa,Yi, Chae S.
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p. 3336 - 3339
(2016/07/06)
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- Stereoselective Ketone Rearrangements with Hypervalent Iodine Reagents
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The first stereoselective version of an iodine(III)-mediated rearrangement of arylketones in the presence of orthoesters is described. The reaction products, α-arylated esters, are very useful intermediates in the synthesis of bioactive compounds such as ibuprofen. With chiral lactic acid-based iodine(III) reagents product selectivities of up to 73 % ee have been achieved.
- Malmedy, Florence,Wirth, Thomas
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supporting information
p. 16072 - 16077
(2016/10/30)
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- Fe(III)-mediated isomerization of α,α-diarylallylic alcohols to ketones: Via radical 1,2-aryl migration
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An Fe(iii)-mediated radical 1,2-aryl migration of α,α-diarylallylic alcohols for the isomerization to ketones is described. The Fe(acac)3-silane would convert the alkene to an alkyl radical and initiates a 1,2-aryl migration-oxidation process. Thus Fe(acac)3 serves as an olefin hydrogen atom transfer initiator and oxidant, while various allylic alcohols could isomerize to ketones in moderate to good yields.
- Deng, Ziyang,Chen, Changwei,Cui, Sunliang
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p. 93753 - 93755
(2016/10/18)
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- Stoichiometric reactions of acylnickel(II) complexes with electrophiles and the catalytic synthesis of ketones
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Acylnickel(II) complexes feature prominently in cross-electrophile coupling (XEC) reactions that form ketones, yet their reactivity has not been systematically investigated. We present here our studies on the reactivity of acylnickel(II) complexes with a series of carbon electrophiles. Bromobenzene, α-chloroethylbenzene, bromooctane, and iodooctane were reacted with (dtbbpy)NiII(C(O)C5H11)(Br) (1b) and (dtbbpy)NiII(C(O)tolyl)(Br) (1c) to form a variety of organic products. While reactions with bromobenzene formed complex mixtures of ketones, reactions with α-chloroethylbenzene were highly selective for the cross-ketone product. Reactions with iodooctane and bromooctane also produced the cross-ketone product, but in intermediate yield and selectivity. In most cases the presence or absence of a chemical reductant (zinc) had only a small effect on the selectivity of the reaction. The coupling of 1c with iodooctane (60% yield) was translated into a catalytic reaction, the carbonylative coupling of bromoarenes with primary bromoalkanes (six examples, 60% average yield).
- Wotal, Alexander C.,Ribson, Ryan D.,Weix, Daniel J.
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supporting information
p. 5874 - 5881
(2015/01/09)
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- DIALKYL(2-ALKOXY-6-AMINOPHENYL)PHOSPHINE, THE PREPARATION METHOD AND USE THEREOF
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The present invention relates to the compound of dialkyl(2-alkoxy-6-aminophenyl)phosphine and the preparation method thereof and the application in the palladium catalyzed coupling reactions of aryl chloride and ketone. The dialkyl(2-alkoxy-6-aminophenyl)phosphine of the present invention could coordinate with the palladium catalyst to highly selectively activate the inert carbon-chlorine bond, and to catalyze direct arylation reaction in the α-position of ketones to produce corresponding coupling compounds. The preparation method of the present invention is a simple one-step method which produces the air-stable dialkyl(2-alkoxy-6-aminophenyl)phosphine. Compared with the synthetic routes of ligands to be used in the activation of carbon-chlorine bonds in the prior arts, the preparation method of the present invention has the advantages of short route and easy operation.
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Paragraph 0037; 0038; 0043; 0044
(2014/10/29)
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- Chiral bronsted acid from a cationic gold(I) complex: Catalytic enantioselective protonation of silyl enol ethers of ketones
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A chiral Bronsted acid has been developed from a cationic gold(I) disphosphine complex in the presence of alcoholic solvent and applied to the enantioselective protonation reaction of silyl enol ethers of ketones. Various optically active cyclic ketones were obtained in excellent yields and high enantioselectivities, including cyclic ketones bearing aliphatic substrates at the α-position. Furthermore, the application of this Bronsted acid was extended to the first Bronsted acid-catalyzed enantioselective protonation reaction of silyl enol ethers of acyclic substrates, regardless of their E/Z ratio.
- Cheon, Cheol Hong,Kanno, Osamu,Toste, F. Dean
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supporting information; experimental part
p. 13248 - 13251
(2011/10/10)
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- A highly active and selective palladium pincer catalyst for the formation of α-aryl ketones via cross-coupling
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Several air and moisture stable Pd(ii) pincer complexes were synthesized via oxidative addition of Pd(0) to novel PheBox pincer ligand precursors. Low loadings (1 mol%) of the Pd complex [t-BuPhebox-Me2]PdBr are capable of efficiently promoting the selective α-monoarylation of a variety of ketones with numerous aryl bromides in only 1 h at 70°C with 82-99% yields.
- Bugarin, Alejandro,Connell, Brian T.
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supporting information; experimental part
p. 7218 - 7220
(2011/08/09)
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- Mild, efficient friedel-Crafts acylations from carboxylic acids using cyanuric chloride and AlCl3
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(Chemical Equation Presented) A mild method for Friedel-Crafts acylation with aromatic and aliphatic carboxylic acids using cyanuric chloride, pyridine, and AlCl3 was developed. Both inter- and intramolecular acylations were achieved at room temperature in high yield and in very short reaction times.
- Kangani, Cyrous O.,Day, Billy W.
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supporting information; experimental part
p. 2645 - 2648
(2009/05/27)
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- MECANISME DE L'ADDITION NUCLEOPHILE AU GROUPEMENT CARBONYLE-I. INFLUENCE DE LA NATURE DU SUBSTITUANT POLAIRE SUR LA STEREOCHIMIE ET LA REACTIVITE DANS LES REACTIONS D'ADDITION DE BROMURE DE METHYLMAGNESIUM AUX ARYL-1 PHENYL-2 PROPANONES
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The influence of a m- or p-polar substituent in 1-aryl 2-phenyl propanones, on addition reactions with CH3MgBr in ether at 30 deg C has been investigated.The invariability of asymmetric induction as a function of substituent, and the correlation of rate constant ratios with Hammett ? constants (ρ=0.24, r=0.97), are consistent with a four-centre pericyclic concerted mechanism with concomitant departure of a solvent molecule.
- Lasperas, M.,Perez-Rubalcaba, A.,Quiroga-Feijoo, M. L.
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p. 3403 - 3408
(2007/10/02)
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