- Construction of reversible hydration-dehydration system by a model compound and a novel polymer bearing vicinal tricarbonyl structure
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A novel polymer bearing acyclic vicinal tricarbonyl moieties in the side chains was synthesized by (1) radical polymerization of a styrene derivative with a 1,3-diketone structure and (2) successive treatment of the resulting polystyrene derivative by N-b
- Dei, Takehito,Morino, Kazuhide,Sudo, Atsushi,Endo, Takeshi
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- Structural insights into the desymmetrization of bulky 1,2-dicarbonyls through enzymatic monoreduction
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Benzil reductases are dehydrogenases preferentially active on aromatic 1,2-diketones, but the reasons for this peculiar substrate recognition have not yet been clarified. The benzil reductase (KRED1-Pglu) from the non-conventional yeast Pichia glucozyma showed excellent activity and stereoselectivity in the monoreduction of space-demanding aromatic 1,2-dicarbonyls, making this enzyme attractive as biocatalyst in organic chemistry. Structural insights into the stereoselective monoreduction of 1,2-diketones catalyzed by KRED1-Pglu were investigated starting from its 1.77 ? resolution crystal structure, followed by QM and classical calculations; this study allowed for the identification and characterization of the KRED1-Pglu reactive site. Once identified the recognition elements involved in the stereoselective desymmetrization of bulky 1,2-dicarbonyls mediated by KRED1-Pglu, a mechanism was proposed together with an in silico prediction of substrates reactivity.
- Rabuffetti, Marco,Cannazza, Pietro,Contente, Martina Letizia,Pinto, Andrea,Romano, Diego,Hoyos, Pilar,Alcantara, Andres R.,Eberini, Ivano,Laurenzi, Tommaso,Gourlay, Louise,Di Pisa, Flavio,Molinari, Francesco
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supporting information
(2021/01/25)
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- Recyclable heterogeneous gold(I)-catalyzed oxidation of internal acylalkynes: Practical access to vicinal tricarbonyls
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A highly efficient heterogeneous gold(I)-catalyzed oxidation of internal acylalkynes has been developed using 2,6-dichloropyridine N-oxide as the oxidant in dichloromethane (CH2Cl2) at room temperature, providing a novel and practical approach for the construction of diverse vicinal tricarbonyls such as α,β-diketoesters, 1,2,3-triketones, and α,β-diketoamides in good to excellent yields. The heterogeneous gold(I) catalyst can be readily obtained via a simple preparative procedure from commercially available reagents and recovered by filtration of the reaction mixture and reused up to seven times without significant loss of catalytic efficiency.
- Hu, Wenli,Huang, Bin,Niu, Bingbo,Cai, Mingzhong
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supporting information
(2021/03/16)
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- Metal-Free Synthesis of Indolopyrans and 2,3-Dihydrofurans Based on Tandem Oxidative Cycloaddition
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The synthesis of versatile scaffold indolopyrans based on C-C radical-radical cross-coupling under metal-free conditions is described. The reaction involving single electron transfer between coupling partners followed by cage collapse allows highly selective cross-coupling while employing only equimolar amounts of coupling partners. Moreover, the mechanistic manifold was expanded for the functionalization of enamines to give the stereoselective synthesis of 2,3-dihydrofurans. This iodine-mediated oxidative coupling features mild conditions and fast reaction kinetics.
- Choi, Subin,Oh, Hyeonji,Sim, Jeongwoo,Yu, Eunsoo,Shin, Seunghoon,Park, Cheol-Min
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supporting information
p. 5528 - 5534
(2020/07/24)
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- Oxidation of β-Ketoamides: The Synthesis of Vicinal Tricarbonyl Amides
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A facile and direct oxidative reaction for the synthesis of vicinal tricarbonyl amides in moderate to excellent yields (53-88%) was developed starting from readily available β-ketoamides in the presence of phenyliodine(III) bis(trifluoroacetate). The resu
- Liu, Yueyang,Zhang, Zhiguo,Wan, Yameng,Zhang, Guisheng,Li, Zhonglian,Bi, Jingjing,Ma, Nana,Liu, Tongxin,Liu, Qingfeng
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p. 3901 - 3907
(2017/04/11)
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- Facile synthesis of 1,2,3-tricarbonyls from 1,3-dicarbonyls mediated by cerium(IV) ammonium nitrate
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A mild and efficient protocol for the synthesis of vicinal tricarbonyl compounds from β-dicarbonyls in a single step using cerium(IV) ammonium nitrate as a catalytic oxidant is described. Ease of execution, wide substrate scope and the suitability for the synthesis of commercially important compounds like ninhydrin, alloxan and oxoline make this reaction particularly noteworthy.
- Sivan, Akhil,Deepthi, Ani
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supporting information
p. 1890 - 1893
(2014/03/21)
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- Regioselective aliphatic carbon-carbon bond cleavage by a model system of relevance to iron-containing acireductone dioxygenase
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Mononuclear Fe(II) complexes ([(6-Ph2TPA)Fe(PhC(O)C(R)C(O)Ph)]X (3-X: R = OH, X = ClO4 or OTf; 4: R = H, X = ClO4)) supported by the 6-Ph2TPA chelate ligand (6-Ph2TPA = N,N-bis((6-phenyl-2-pyridyl)methyl)-N-(2-pyridylmethyl)amine) and containing a β-diketonate ligand bound via a six-membered chelate ring have been synthesized. The complexes have all been characterized by 1H NMR, UV-vis, and infrared spectroscopy and variably by elemental analysis, mass spectrometry, and X-ray crystallography. Treatment of dry CH3CN solutions of 3-OTf with O2 leads to oxidative cleavage of the C(1)-C(2) and C(2)-C(3) bonds of the acireductone via a dioxygenase reaction, leading to formation of carbon monoxide and 2 equiv of benzoic acid as well as two other products not derived from dioxygenase reactivity: 2-oxo-2- phenylethylbenzoate and benzil. Treatment of CH3CN/H2O solutions of 3-X with O2 leads to the formation of an additional product, benzoylformic acid, indicative of the operation of a new reaction pathway in which only the C(1)-C(2) bond is cleaved. Mechanistic studies show that the change in regioselectivity is due to the hydration of a vicinal triketone intermediate in the presence of both an iron center and water. This is the first structural and functional model of relevance to iron-containing acireductone dioxygenase (Fe-ARD′), an enzyme in the methionine salvage pathway that catalyzes the regiospecific oxidation of 1,2-dihydroxy-3-oxo-(S)- methylthiopentene to form 2-oxo-4-methylthiobutyrate. Importantly, this model system is found to control the regioselectivity of aliphatic carbon-carbon bond cleavage by changes involving an intermediate in the reaction pathway, rather than by the binding mode of the substrate, as had been proposed in studies of acireductone enzymes.
- Allpress, Caleb J.,Grubel, Katarzyna,Szajna-Fuller, Ewa,Arif, Atta M.,Berreau, Lisa M.
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p. 659 - 668
(2013/03/14)
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- Reversible cross-linking and de-cross-linking system of polystyrenes bearing the monohydrate structure of vicinal tricarbonyl group through water-alcohol exchange reactions at ambient conditions
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We describe in this paper reversible cross-linking and de-cross-linking system based on a polystyrene derivative bearing monohydrate structure of vicinal tricarbonyl groups with 1,6-hexanediol utilizing the direct water-alcohol exchange reactions on the v
- Yonekawa, Morio,Furusho, Yoshio,Endo, Takeshi
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p. 6640 - 6647
(2012/10/30)
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- Iodine-catalyzed synthesis of 1,2-diaryldiketones by oxidative cleavage of 1,3-diaryldiketones with DMSO
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A metal-free, efficient, practical, and convenient process based on an iodine-catalyzed oxidative cleavage reaction has been developed to form 1,2-diaryldiketons in high yields from 1,3-diaryldiketones. The reaction is performed in DMSO and in air, and a mechanism was proposed according to the reaction evidence. Copyright
- Yuan, Yu,Zhu, Haitao
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scheme or table
p. 329 - 333
(2012/02/04)
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- Mechanistic studies of the O2-dependent aliphatic carbon-carbon bond cleavage reaction of a nickel enolate complex
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The mononuclear nickel(II) enolate complex [(6-Ph2TPA)Ni(PhC(O)C(OH)C(O)Ph] ClO4 (I) was the first reactive model complex for the enzyme/substrate (ES) adduct in nickel(II)-containing acireductone dioxygenases (ARDs) to be reported. In this contribution, the mechanism of its O 2-dependent aliphatic carbon-carbon bond cleavage reactivity was further investigated. Stopped-flow kinetic studies revealed that the reaction of I with O2 is second-order overall and is ~ 80 times slower at 25 °C than the reaction involving the enolate salt [Me4N][PhC(O) C(OH)C(O)Ph]. Computational studies of the reaction of the anion [PhC(O)C(OH)C(O)Ph]- with O2 support a hydroperoxide mechanism wherein the first step is a redox process that results in the formation of 1,3-diphenylpropanetrione and HOO-. Independent experiments indicate that the reaction between 1,3-diphenylpropanetrione and HOO- results in oxidative aliphatic carbon-carbon bond cleavage and the formation of benzoic acid, benzoate, and CO:CO2 ( ~ 12:1). Experiments in the presence of a nickel(II) complex gave a similar product distribution, albeit benzil [PhC(O)C(O)Ph] is also formed, and the CO:CO2 ratio is ~ 1.5:1. The results for the nickel(II)-containing reaction match those found for the reaction of I with O2 and provide support for a trione/HOO- pathway for aliphatic carbon-carbon bond cleavage. Overall, I is a reasonable structural model for the ES adduct formed in the active site of Ni"ARD. However, the presence of phenyl appendages at both C(1) and C(3) in the [PhC(O)C(OH)C(O)Ph]- anion results in a reaction pathway for O2-dependent aliphatic carbon-carbon bond cleavage (via a trione intermediate) that differs from that accessible to C(1)- H acireductone species. This study, as the first detailed investigation of the O2 reactivity of a nickel(II) enolate complex of relevance to Ni"ARD, provides insight toward understanding the chemical factors involved in the O2 reactivity of metal acireductone species.
- Berreau, Lisa M.,Borowski, Tomasz,Grubel, Katarzyna,Allpress, Caleb J.,Wikstrom, Jeffrey P.,Germain, Meaghan E.,Rybak-Akimova, Elena V.,Tierney, David L.
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experimental part
p. 1047 - 1057
(2011/05/05)
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- Novel oxygenations with IBX
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Universal remedy: The α-hydroxylation of β-keto esters and a range of other suitably substituted carbonyl compounds can be effected in the presence of IBX (2-iodoxybenzoic acid). This novel reactivity underscores the importance of IBX as a universally applicable oxidizing agent.
- Duschek, Alexander,Kirsch, Stefan F.
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supporting information; experimental part
p. 10713 - 10717
(2010/04/05)
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- The Hydration of 1,2,3-Indanetriones and Related Triones
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A series of 5-mono- and 5,6-di-substituted 1,2,3-indanetriones, 1,2,3(2H)-phenalenetrione and 1,3-diphenyl-1,2,3-propanetrione have been shown to form 2,2-dihydroxy-1,3-dione hydrates.The rates for the uncatalysed hydrations has been measured at three temperatures and activation paramaters evaluated.The kinetic role of water and solvent isotope effects have been studied.The Hammett reaction constant, ρ, for the uncatalysed hydration of the substituted 1,2,3-indanetriones in 96.7percent (v/v) dioxane-water at 25 deg C was found to be ca. 1.05.The structure of the transition state for the hydration has been discussed and shown to involve two molecules of water, one acting as a nucleophile and the other as a general acid-base catalyst transferring protons.
- Bowden, Keith,Rumpal, Sanjay
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p. 355 - 374
(2007/10/03)
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- Highly Efficient Hydroxylation of Carbonyl Compounds with Dimethyldioxirane
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The enolates and/or enols of ketones, esters, β-diketones, β-oxo esters, and β-oxolactones were transformed by dimethyldioxirane (isolated in acetone solution or generated in situ) into their α-hydroxy compounds in good to excellent yields.The direct hydroxylation of the enols was significantly enhanced by the use of fluoride ion.For the enolate of camphor the exo/endo diastereoselectivity depended significantly on the metal ligand; the highest exo/endo ratio (93:7) was observed for the enol trimethylsilyl ether of camphor.Key Words: Dimethyldioxirane / Enolates / Hydroxylation / α-Hydroxy carbonyl compounds / Enol silyl ethers
- Adam, Waldemar,Prechtl, Frank
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p. 2369 - 2372
(2007/10/02)
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- A Facile One-Pot Synthesis of Vicinal Di- and Triketones from α-Methylene Ketones by NBS-DMSO Oxidation
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The reaction of 1,2-diarylethanones (1a-u) with N-bromosuccinimide in anhydrous dimethyl sulphoxide afforded diarylethanediones (2a-u) in excellent yields.Under similar conditions, 1-phenyl-2-butanone (3) gave 1-phenyl-1,2-butanedione (4) in fair yield in addition to a small amount of 1-phenyl-3-methylthio-1,2-butanedione (5) and 1-phenyl-1-methylthio-2-butanone (6). 4-Phenyl-2-butanone (7), 1,3-diphenyl-2-propanone (9), and 1,3-diphenyl-1,3-propanedione (10) gave the corresponding triketones monohydrate (8) and (11). 1-Indanone (12), 2-indanone (13), and 1,3-indandione (14) gave ninhydrin (15) in good yields.In the case of 3-phenyl-1-indanone (16), 3-phenyl-2-bromo-1-indanone (17), 3-phenyl-2-bromo-1-indenone (18) and 3-phenyl-1-indenone (19) were obtained. 1-Phenyl-1-propanone (20) and 1-phenyl-1-butanone (22) gave the corresponding α-(methylthio)ketones (21) and (22). 1,3,3-Triphenylpropanone (24a) and 1-phenyl-3-methyl-1-butanone (24b) yielded only the corresponding α-bromoketones (25a,b) in good yields.These α-bromoketones, however, afforded the corresponding α-diketones (26a,b) in moderate yields when α-bromoketones reacted with dimethyl sulphoxide in the presence of AgBF4.
- Tatsugi, Jiro,Izawa, Yasuji
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p. 2747 - 2763
(2007/10/02)
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- Singel-Oxygen Photolysis of Dihaloketones. A Facile and Efficient Approach to Vicinal Triketones and Their Monohydrates
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The preparation of vic-triketones and/or their monohydrates by sensitized photooxidation (singlet oxygen) of gem-dihaloketones and/or vic-dihaloketones is described; some reaction mechanisms are discussed.
- Mahran, M. Refat,Abdou, Wafaa M.,Sidky, Mahmoud M.,Wamhoff, Heinrich
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p. 506 - 508
(2007/10/02)
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- The Oxidation of Acetophenones to Arylglyoxals with Aqueous Hydrobromic Acid in Dimethyl Sulfoxide
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The reaction of acetophenones with aqueous hydrobromic acid (HBr) in dimethyl sulfoxide (Me2SO) leads to the formation of arylglyoxals in good yield.Evidence has been obtained which suggests that this oxidation is mediated by a low concentration of molecular bromine, with the consecutive intermediacy of the α-bromo- and α-hydroxyacetophenones.The reaction of α-bromoacetophenone 2 with Me2SO alone provides the arylglyoxal 4 with the glyoxylic acid 6 as the major products.The α-hydroxyacetophenone 3 and thiol ester 5 are intermediates leading to 4 and 6, respectively, and may be isolated as minor products.The presence of water in the medium suppresses the formation of 5 and 6 and results in a cleaner conversion to 4.Treatment of aryl aldehyde 13 with 14 followed by reaction of the resulting 15 with aqueous HBr in Me2SO gave arylglyoxal 4 in good yield.
- Floyd, M. Brawner,Du, Mila T.,Fabio, Paul F.,Jacob, Linda A.,Johnson, Bernard D.
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p. 5022 - 5027
(2007/10/02)
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- IODONIUM DERIVATIVES OF β-DIKETONES. XX. NEW METHOD FOR THE PRODUCTION OF PHENYLIODONIUM BETAINES OF 1,3-INDANEDIONES AND THEIR CLEAVAGE BY NITRIC ACID. USE OF THE CLEAVAGE OF PHENYLIODONIUM BETAINES FOR THE PRODUCTION OF 1,2,3-TRICARBONYL COMPOUNDS
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The reaction of 1,3-indanediones and its derivatives substituted in the phthaloyl ring with (diacetoxyiodo)benzene in a mixture of chloroform, ethanol, and diethyl ether at 7-12 deg C gives the corresponding phenyliodonium betaines with good yields.Cleavage of the phenyliodonium betaines of β-dicarbonyl compounds by nitric acid leads to the hydrates of the 1,2,3-tricarbonyl compounds.The reaction is limited by the high CH acidity of the β-dicarbonyl compound.
- Prikule, D. E.,Neiland, O. Ya.
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p. 1888 - 1890
(2007/10/02)
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