- 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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- Iodine-catalyzed α,β-dehydrogenation of ketones and aldehydes generating conjugated enones and enals
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A transition metal-free α,β-dehydrogenation of ketones and aldehydes was developed. This reaction was conducted in a facile I2/KI/DMSO system to produce the corresponding unsaturated compounds in good to high yields. The gram-scale experiment also indicated the potential synthetic value of this new reaction in organic synthesis. In the reaction, DMSO acted as both solvent and mild oxidant.
- Cao, Yuanjie,Chen, Tieqiao,Huang, Tianzeng,Liu, Long
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p. 8697 - 8701
(2020/06/08)
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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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- LiBr/β-CD/IBX/H2O-DMSO: A new approach for one-pot biomimetic regioselective ring opening of chalcone epoxides to bromohydrins and conversion to 1,2,3-triketones
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Highly regioselective ring cleavage of chalcone epoxides to bromohydrins has been carried out in good yields with LiBr in the presence of β-CD using DMSO-H2O as solvent system. The ring-opened product, i.e., bromohydrin, was well adapted to IBX-mediated oxidation in such a fashion that the bromohydrins are transformed to their corresponding 1,2,3-triketones in moderate-to-good yields in one pot.
- Verma, Nishant,Kumar, Sumit,Ahmed, Naseem
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supporting information
p. 1110 - 1120
(2017/05/25)
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- Anion Effects in Oxidative Aliphatic Carbon-Carbon Bond Cleavage Reactions of Cu(II) Chlorodiketonate Complexes
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Aliphatic oxidative carbon-carbon bond cleavage reactions involving Cu(II) catalysts and O2 as the terminal oxidant are of significant current interest. However, little is currently known regarding how the nature of the Cu(II) catalyst, including the anions present, influence the reaction with O2. In previous work, we found that exposure of the Cu(II) chlorodiketonate complex [(6-Ph2TPA)Cu(PhC(O)CClC(O)Ph)]ClO4 (1) to O2 results in oxidative aliphatic carbon-carbon bond cleavage within the diketonate unit, leading to the formation of benzoic acid, benzoic anhydride, benzil, and 1,3-diphenylpropanedione as organic products. Kinetic studies of this reaction revealed a slow induction phase followed by a rapid decay of the absorption features of 1. Notably, the induction phase is not present when the reaction is performed in the presence of a catalytic amount of chloride anion. In the studies presented herein, a combination of spectroscopic (UV-vis, EPR) and density functional theory (DFT) methods have been used to examine the chloride and benzoate ion binding properties of 1 under anaerobic conditions. These studies provide evidence that each anion coordinates in an axial position of the Cu(II) center. DFT studies reveal that the presence of the anion in the Cu(II) coordination sphere decreases the barrier for O2 activation and the formation of a Cu(II)-peroxo species. Notably, the chloride anion more effectively lowers the barrier associated with O-O bond cleavage. Thus, the nature of the anion plays an important role in determining the rate of reaction of the diketonate complex with O2. The same type of anion effects were observed in the O2 reactivity of the simple Cu(II)-bipyridine complex [(bpy)Cu(PhC(O)C(Cl)C(O)Ph)ClO4] (3).
- Saraf, Sushma L.,Mi?aczewska, Anna,Borowski, Tomasz,James, Christopher D.,Tierney, David L.,Popova, Marina,Arif, Atta M.,Berreau, Lisa M.
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p. 6916 - 6928
(2016/07/26)
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- Reversible capture and release of aromatic amines by vicinal tricarbonyl compound
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In this paper, we report reversible capture and release of aromatic amines by diphenylpropanetrione (DPPT). Addition of aromatic amines to the central carbonyl group occurred readily at ambient temperature to provide the aromatic amine adducts of DPPT (DPPT-aromatic amines), which has a hemiaminal structure. On the other hand, washing a solution of DPPT-aromatic amine with diluted hydrochloric acid (HCl) enabled successful recovery of DPPT to demonstrate the reversible nature of this system.
- Yuki, Tatsuya,Yonekawa, Morio,Furusho, Yoshio,Sei, Yoshihisa,Tomita, Ikuyoshi,Endo, Takeshi
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p. 2868 - 2873
(2016/05/19)
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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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- CAN-catalyzed rapid C-O bond formation towards α-aminoxylation of ketones
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A simple and efficient approach towards α-oxyaminated ketones has been developed through CAN-catalyzed C-O bond formation with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). The environmentally friendly transformation is practical due to the use of commercial available catalyst, easy operating procedures, the broad substrate scope, and short reaction time.
- Feng, Peng,Song, Song,Zhang, Li-He,Jiao, Ning
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supporting information
p. 2717 - 2720
(2015/01/08)
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- DDQ-mediated oxidation of sp3 C-H bond for the direct synthesis of vicinal tricarbonyl compounds Dedicated to academician Li-Xin Dai on the occasion of his 90th birthday
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A facile and direct synthetic method was developed for the construction of vicinal tricarbonyl compounds (VTCs) in moderate to excellent yields (46-92%), by treating the readily available 1,3-dicarbonyl compounds with 2,2,6,6-tetramethylpiperidine-1-oxyl
- Wang, Zheng-Lin,An, Xing-Lan,Ge, Li-Shi,Jin, Jing-Hai,Luo, Xiaoyan,Deng, Wei-Ping
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p. 3788 - 3792
(2014/05/20)
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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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- 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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experimental part
p. 2245 - 2251
(2012/04/23)
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- Catalytic oxidations of enolizable ketones using 2-alkylidene-4- oxothiazolidine vinyl bromide
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Direct oxidation of enolizable ketones to α-hydroxy derivatives, vicinal dicarbonyls or tricarbonyl compounds has been achieved by a catalytic amount of 2-alkylidene-4-oxothiazolidine vinyl bromide in DMSO as a solvent. The yields range from moderate to good.
- Baranac-Stojanovi?, Marija,Markovi?, Rade,Stojanovi?, Milovan
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experimental part
p. 8000 - 8008
(2011/11/06)
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- Catalytic oxidative cleavage of 1,3-diketones to carboxylic acids by aerobic photooxidation with iodine
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We report the catalytic oxidative cleavage of 1,3-diketones to the corresponding carboxylic acids by aerobic photooxidation with iodine under irradiation with a high-pressure mercury lamp. Georg Thieme Verlag Stuttgart. New York.
- Tada, Norihiro,Shomura, Motoki,Cui, Lei,Nobuta, Tomoya,Miura, Tsuyoshi,Itoh, Akichika
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scheme or table
p. 2896 - 2900
(2012/01/03)
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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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- Formation of α-hydroxy-β-diketones through hydroxylation of isoxazolium salts: Stereoselective approach to angular cis-diols in polycyclic systems
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Only two steps were needed for the unprecedented oxidation of isoxazoles, which is exploited in the stereocontrolled introduction of an "angular cis-diol" characteristic of polyketide-derived polycyclic natural products, suchas 3. In this two-step process, 1) N-methylation of isoxazole 1 and 2) stereoselective epoxidation of isoxazolium salt 2 withsodium hypochlorite followed by hydrolysis are carried out (Bn: benzyl). (Chemical Equation Presented)
- Takikawa, Hiroshi,Takada, Akiomi,Hikita, Katsuyoshi,Suzuki, Keisuke
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body text
p. 7446 - 7449
(2009/03/12)
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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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- Photochemical reactions of alkyl phenylglyoxylates
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Three new photoproducts, ethyl O-benzoyl mandelate (5a), ethyl O-acetylmandelate (6a), and biphenyl triketone (7a) are isolated and identified in the reactions of ethyl phenylglyoxylate (1a) in benzene. Quantum yields and initial rate constants of product formation are shown to be concentration dependent. For the formation of carbonyl product 3 at lower starting material concentrations (N) and intermolecular H abstraction (k1) of methyl phenylglyoxylate (1d) are measured.
- Hu, Shengkui,Neckers, Douglas C.
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p. 6407 - 6415
(2007/10/03)
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- The Conversion of α-Bromo-β-Dicarbonyls to Vicinal Tricarbonyls Using Dimethyldioxirane and Base
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Vicinal tricarbonyls are prepared from α-bromo-β-dicarbonyl precursors by base promoted oxygen transfer from dimethyldioxirane.The α-bromo-β-dicarbonyls were prepared by the reaction of CuBr2 and benzene (Koser's reagent) with a β-dicarbonyl system.
- Coats, Steven J.,Wasserman, Harry H.
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p. 7735 - 7738
(2007/10/02)
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- A novel application of the Dess-Martin reagent to the synthesis of an FK506 analogue and other tricarbonyl compounds
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The use of the Dess-Martin reagent for the oxidation of β-hydroxy and β-ketoamides, esters and ketones to the corresponding tricarbonyl compounds is reported. The method is shown to be applicable to the synthesis of analogues of the immunosuppressant FK506.
- Batchelor,Gillespie,Golec,Hedgecock
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p. 167 - 170
(2007/10/02)
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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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- Synthesis and Chemistry of Acyltriazolinedione Ylides and Related Intermediates: New Methods for the Preparation of Di- and Tricarbonyl Compounds
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α-Urazolylcarbonyl compounds can be easily oxidized to the corresponding ylides, and these ylides hydrolyzed to the corresponding carbonyl compounds.In addition these same urazole precursors can be converted to carbonyl compounds via a novel version of the Swern oxidation.These two methods not only are of synthetic value in the preparation of 1,2-dicarbonyl and 1,2,3-tricarbonyl compounds but also serve as useful probes for the formation of triazolinedione ylides and the related urazolium species.
- Wilson, R. Marshall,Hengge, Alvan C.
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p. 197 - 202
(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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- Heterocyclen aus α-Nitroolefinen. XII. 3-Acetyl-4,5-dihydro-5-(methyleneamino)furane und 3-Acylpyrrole aus α-Nitroolefinen und β-Diketonen
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From α-nitroolefines 1 and β-diketones 2 3-acetyl-4,5-dihydro-5-(methyleneamino)furans 5 are prepared.Furans 5 react in acid medium to yield 1-unsubstituted 3-acylpyrroles 6, catalytic hydrogenation yields 1-substituted 3-acylpyroles 9.The (1)H-nmr and (13)C-nmr investigation prove the constitutions.
- Boberg, Friedrich,Garburg, Karl-Heinz,Goerlich, Karl-Joachim,Pipereit, Eberhard,Redelfs, Elke,Ruhr, Maria
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p. 1853 - 1859
(2007/10/02)
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- THE FLUORIDE ION EFFECT IN THE REACTIONS OF SINGLET OXYGEN WITH ENOLS
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The fluoride ion effect in the reaction of enolic systems with singlet oxygen has been investigated. β-Dicarbonyl compounds yielded 1,2,3-tricarbonyl derivatives, some of which underwent further hydration, whereas α-diketones suffered oxidative decarboxylation to give open-chain aldehydo-acids or keto-acids.
- Wasserman, Harry H.,Pickett, James E.
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p. 2155 - 2162
(2007/10/02)
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- Reactions of Diphenylcyclopropenone and Tetracyclones with Potassium Superoxide
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Reactions of diphenylcyclopropenone and various tetracyclones with potassium superoxide are reported.
- Neckers, Douglas C.,Hauck, Gerhard
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p. 4691 - 4695
(2007/10/02)
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- Introduction of Oxygen Functions into the α-Position of β-Diketones, 8. Ozonolysis of Sulfonium Ylides
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(Dimethylsulfonio)diacylmethanides 1, prepared by known methods, are cleaved by equimolar amounts of ozone in aprotic medium yielding vicinal triketones 2 and DMSO.Peroxydic reaction products are not detectable.
- Schank, Kurt,Schuhknecht, Christoph
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p. 3032 - 3041
(2007/10/02)
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- Stable Enols of α-dibenzoylmethanes
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The enols 13a-m of α-(aryloxy)- and α-(alkyloxy)dibenzoylmethanes 4a-m are obtained by decomposition of the copper chelates 11a-m with sulfuric acid.The copper compounds are synthesized either by ester condensation of the acetophenones 6h-m with phenyl benzoate (7) or by nucleophilic substitution of α-bromodibenzoylmethane (9) with the phenols 10a-g.The enolates 8, primarily formed in the presence of sodium hydride or triethylamine, respectively, are directly converted into the chelates 11 with copper(II) acetate.The enols 13 are characterized by isomerization to the β-diketones 4 as well as by bromination to 12.
- Regitz, Manfred,Schaefer, Ansgar
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p. 1172 - 1185
(2007/10/02)
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