- Dehydrogenative Coupling of Benzylic and Aldehydic C-H Bonds
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A photoinduced dehydrogenative coupling reaction between benzylic and aldehydic C-H bonds is reported. When a solution of an alkylbenzene and an aldehyde in ethyl acetate is irradiated with visible light in the presence of iridium and nickel catalysts, a coupled α-aryl ketone is formed with evolution of dihydrogen. An analogous C-C bond forming reaction occurs between a C-H bond next to the nitrogen of an N-methylamide and an aldehydic C-H bond to produce an α-amino ketone. These reactions provide a straightforward pathway from readily available materials leading to valued structural motifs of pharmacological relevance.
- Ishida, Naoki,Kawasaki, Tairin,Murakami, Masahiro
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supporting information
p. 3366 - 3370
(2020/03/06)
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- Product selectivity in the electroreduction of thioesters
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The electroreduction of differently substituted aromatic and aliphatic thioesters (RCOSR′) led to regioselective reactions depending on the nature of the substituents. Thus, the cleavage between the carbonyl group and the SR′ group afforded α-diketones an
- We?wer,Olivero,Du?ach
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p. 1709 - 1714
(2007/10/03)
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- Samarium diiodide promoted formation of 1,2-diketones and 1-acylamido-2-substituted benzimidazoles from N-acylbenzotriazoles
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N-Acylbenzotriazoles, when treated with samarium diiodide in THF, undergo self-coupling reaction to afford 1,2-diketones in good to excellent yields; while when treated with samarium diiodide in CH3CN, they undergo ring-opening reaction to afford 1-acylamido-2-alkyl (or aryl) benzimidazoles in reasonable to good yields. A plausible mechanism was suggested.
- Wang, Xiaoxia,Zhang, Yongmin
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p. 4201 - 4207
(2007/10/03)
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- Lewis acid assisted permanganate oxidations
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Lewis acids combine with permanganate in acetone solutions to form a complex that has enhanced oxidizing capabilities. The use of Lewis acids under these conditions to promote permanganate oxidations is superior to the use of Bronsted acids because the latter promote enolization of the solvent and subsequent unproductive reduction of the oxidant. The products obtained from a variety of alkenes, alkynes, arenes, sulfides, alcohols and ethers have been identified and probable reaction mechanisms proposed.
- Lai, Sheng,Lee, Donald G.
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p. 9879 - 9887
(2007/10/03)
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- Formation of 1,2-diketones by samarium diiodide promoted reaction of N-acylbenzotriazoles
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Transformation of N-acylbenzotriazoles 1 into 1,2-diketones 2 in good to excellent yields has been realized by the use of samarium diiodide at room temperature.
- Wang, Xiaoxia,Zhang, Yongmin
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p. 5431 - 5433
(2007/10/03)
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- Oxidation of alkylphenylacetylenes and dialkylacetylenes on palladium catalysts in DMSO
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Alkylphenyl-and dialkylacetylenes are oxidized by the DMSO-PdCl2 or DMSO-Pd/C system to give the corresponding 1,2-diketones. Oxidation of these compounds, unlike that of diarylacetylenes, is less selective and is accompanied by the partial cle
- Yusubov,Filimonov,Chi, Ki-Whan
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p. 649 - 653
(2007/10/03)
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- Ruthenium Tetroxide Oxidation of Alkenes. A More Complete Picture
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The ruthenium tetroxide oxidation of some linear and cyclic alkenes, representatives of five substitution patterns, has been performed in acetone-water (5:1) solution at -70 deg C using stoichiometric ammounts of the oxidant.The main reaction products are 1,2-diols and/or α-ketols depending on the nature of the substrate little amounts of scission products, aldehydes and/or carboxylic acids, are also obtained.Generally 1,2-diols predominate over α-ketols except in the oxidation of (-)-α-pinene that afforded the α-ketol in 51percent yield while no trace of the corresponding 1,2-diol was detected.All reactions prceeded through the formation of unstable brownish precipitates, presumably the intermediate ruthenium (VI) esters, which easily decomposed during the work-up step.Results from oxidation of trans-7-tetradecene and cis and trans-11-tetradecenyl acetate indicated that the reaction was syn stereospecific.In some cases, 1,3-dioxolane products, formed by condensation of the 1,2-diol and the aldehyde materials, were also obtained among the reaction products.Their possible origin is briefly discussed.
- Albarella, Laura,Piccialli, Vincenzo,Sica, Donato,Smaldone, Dina
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p. 2442 - 2456
(2007/10/03)
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- Cobalt(II)-Catalyzed Reaction of Aldehydes with Acetic Anhydride under an Oxygen Atmosphere: Scope and Mechanism
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The reaction of aldehydes with acetic anhydride in the presence of catalytic cobalt(II) chloride under an oxygen atmosphere at ambient temperature is dependent upon the reaction medium.Aliphatic aldehydes react in acetonitrile to give 1,2-diones whereas the aromatic aldehydes are acylated to yield the corresponding acylals.On the other hand, carboxylic acids are obtained from aliphatic and aromatic aldehydes by conducting the reaction in dichloroethane or benzene.Cobalt(II) chloride in acetonitrile catalyzes the conversion of aliphatic aldehydes to the correspondinganhydrides in the absence of acetic anhydride whereas aromatic aldehydes remain largely unaffected under these conditions.A preliminary mechanistic study in three different solvents (i.e. acetonitrile, dichloroethane, and DMF) has revealed that in acetonitrile and in the presence of acetic anhydride, aliphatic aldehydes behave differently than aromatic aldehydes.Some trapping experiments using methyl acrylate and stilbene have been conducted to demonstrate the occurence of an acyl cobalt and peroxyacyl cobalt intermediate during these reactions.
- Bhatia, Beena,Punniyamurthy, T.,Iqbal, Javed
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p. 5518 - 5523
(2007/10/02)
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- ACYLSILANE-MEDIATED NUCLEOPHILIC ACYLATION OF α,β-UNSATURATED CARBONYL DERIVATIVES
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A number of 1,4-diketones and of γ-keto esters can be prepared regiospecifically under mild conditions by employing a TBACN-catalysed Michael addition of acylsilanes to α,β-unsaturated carbonyl derivatives.
- degl'Innocenti, Alessandro,Ricci, Alfredo,Mordini, Alessandro,Reginato, Gianna,Colotta, Vittoria
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p. 645 - 648
(2007/10/02)
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- A Simple and Improved Procedure for the Conversion of Alkynes to 1,2-Diketones by Indirect Electrooxidation With Ruthenium Tetroxide as a Mediator
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Indirect electrooxidation of alkynes 1 using ruthenium tetroxide as a mediator, leading to 1,2-diones 2 in 72-87percent, is described.The electrolysis is carried out in the presence of a catalytic amount of ruthenium dioxide dihydrate in a two phase system of saturated aqueous sodium chloride and carbon tetrachloride.The overoxidation of 1,2-diones to the corresponding carboxylic acid, an unavoidable drawback generally encountered in the metal oxidation of acetylenes, is suppressed greatly by maintaining the pH of the aqueous phase at 4 and conducting the reaction at 0-5 deg C.The synthetic utility of this electrochemical oxidation is exemplified by the preparation of 2i (82percent), a key intermediate for the synthesis of furaneol 4, from the commercially available 1i.
- Torii, Sigeru,Inokuchi, Tsutomu,Hirata, Youzou
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p. 377 - 379
(2007/10/02)
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