- A Convenient Ruthenium-Catalysed α-Methylation of Carbonyl Compounds using Methanol
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An efficient ruthenium catalyst is reported, for the first time, to catalyse the α-methylation of ketones and esters using methanol as a green methylating agent. The in situ generated catalyst from the complexes [RuCp*Cl2]2or [RuCp*Cl2]nwith dpePhos provided up to quantitative yields in the presence of only 20 mol% of lithium tert-butoxide (LiO-t-Bu) as a base. Regioselective mono- or multi-methylation could be effectively controlled by temperature. This catalyst system was also effective for the one-pot sequential α-alkylation–α-methylation of methyl ketones and conjugate reduction–α-methylation of α,β-unsaturated ketones to synthesise α-branched ketones. An application of the α-methylation of esters using the ruthenium catalyst was demonstrated for an alternative catalytic synthesis of Ketoprofen. (Figure presented.).
- Dang, Tuan Thanh,Seayad, Abdul Majeed
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- Enamines as Surrogates of Alkyl Carbanions for the Direct Conversion of Secondary Amides to α-Branched Ketones
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A direct transformation of secondary amides into α-branched ketones with enamines as soft alkylation reagents was developed. In this reaction, enamines serve as surrogates of alkyl carbanions, rather than the conventional enolates equivalents in the Stork's reactions, which allowed for the easy introduction of alkyl groups with electrophilic functional groups. In the presence of 4 ? molecular sieves, the method can be extended to the one-pot coupling of secondary amides with aldehydes to yield ketones. (Figure presented.).
- Liu, Yong-Peng,Wang, Shu-Ren,Chen, Ting-Ting,Yu, Cun-Cun,Wang, Ai-E,Huang, Pei-Qiang
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supporting information
p. 971 - 975
(2019/01/25)
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- Palladium-catalyzed arylation of vinylic acetates. Phosphine ligand influenced regioselectivity
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A palladium-catalyzed coupling reaction of aryl bromides with vinylic acetates in the presence of tributyltin methoxide h as been described. The α-arylation aldehyde product and the aryl ketone were obtained in the presence of P(t-Bu)3 and P(o-
- Jean, Micka?l,Renault, Jacques,Van De Weghe, Pierre
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supporting information; experimental part
p. 6546 - 6548
(2011/02/23)
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- Ozone-mediated Nitration of Aromatic Ketones and Related Compounds with Nitrogen Dioxide
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Alkyl aryl ketones react smoothly with nitrogen dioxide at low temperatures in the presence of ozone to give ortho- and meta-nitro derivatives as the principal products, the former usually being predominant (ortho:meta = 1.1-3.8:1.0).No attack was observed on the alkyl side chains.
- Suzuki, Hitomi,Murashima, Takashi
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p. 903 - 908
(2007/10/02)
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- Kinetics, Isotope Effects, and Mechanism of the Reaction of 1-Nitro-1-(4-nitrophenyl)alkanes with DBU in Acetonitrile
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The kinetics of the reaction of O2NC6H4C(L)(R)NO2 (R = Me, Et, Pri, NNPE, NNPP, or MNNPP, respectively; L = H, D) with 1,8-diazabicycloundec-7-ene (DBU) in acetonitrile (MeCN) are reported.The nature of the product indicates that substantial dissociation into free ions occurs.The usefulness of Benesi-Hildebrand relationship for distinguishing between ion pairs and ions of the product is discussed in detail.The reaction shows low activation enthalpy value ΔH(excit.) = 15.4, 17.8, and 19.9 kJ mol-1 and large negative entropies of activation ΔS(excit.) = -131, -134, and -147 J mol-1 K-1 for NNPE, NNPP, and MNNPP respectively.The kinetic isotope effects kH/kD (12.5, 12.4, and 12.3) are large, showing no variation, the more sterically hindered the substrate.The values of the isotope effects exerted on the activation parameters indicate the contribution of a tunnelling effect QH/QD = 1.35 at 25 deg C.The influence of water on the kinetics is also examined and discussed with respect to reliability of kinetic measurements of such reactions systems.
- Galezowski, Wlodzimierz,Jarczewski, Arnold
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p. 1647 - 1656
(2007/10/02)
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- Enamines: Part IV - Synthesis of Nitro Substituted Alkyl Phenyl Ketones
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Nitro substituted alkyl phenyl ketones (V) have been synthesised by reacting nitro substituted benzoyl chlorides (II) with morpholine enamines (I) of aliphatic aldehydes.The resulting acylated enamines (III) on hydrolysis afford the desired V.However, 2-n
- Kulkarni, Sheshgiri N.,Bhamare, N. K.,Kamath, H. V.
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p. 168 - 170
(2007/10/02)
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