- First detection of a chloroperoxidase in bryophytes
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Chlorinated cyclic bisbibenzyls of the isoplagiochin type are the first verified halometabolites from bryophytes. They could be obtained by in vitro chlorination of isoplagiochin C with chloroperoxidase from Caldariomyces fumago. Furthermore, an enzyme of
- Speicher, Andreas,Heisel, Ronny,Kolz, Juergen
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Read Online
- Solvent-free preparation of α,α-dichloroketones with sulfuryl chloride
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An efficient and facile method is reported for the synthesis of a series of α,α-dichloroketones. The direct dichlorination of methyl ketones and 1,3-dicarbonyls using an excess amount of sulfuryl chloride affords the corresponding gem-dichloro compounds in moderate to excellent yields. Moreover, the protocol features high yields, broad substrate scope, and simple reaction conditions without using any catalysts and solvents.
- Tu, Dewei,Luo, Juan,Jiang, Wengao,Tang, Qiang
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supporting information
(2021/09/15)
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- New syntheses of haloketo acid methyl esters and their transformation to halolactones by reductive cyclization
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A new method for haloketo acid methyl ester synthesis on the basis of the ring-opening of cyclic α,β-unsaturated ketones followed by halogenation under mild conditions is reported. Di- and tri-haloketo acid methyl esters are conveniently synthesized via the hydrolytic ring-opening reaction through this method. Halolactones were readily obtained from these haloketo acid methyl esters by reductive cyclization employing NaBH4 and trifluoroacetic acid. Derivatizations of the obtained halolactone utilizing the exo-halomethylene moiety were also demonstrated.
- China, H.,Dohi, T.,Fujitake, M.,Kageyama, N.,Kikushima, K.,Yatabe, H.
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p. 1804 - 1810
(2020/10/16)
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- Myeloperoxidase-mediated oxidation of edaravone produces an apparent non-toxic free radical metabolite and modulates hydrogen peroxide-mediated cytotoxicity in HL-60?cells
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Edaravone is considered to be a potent antioxidant drug known to scavenge free radical species and prevent free radical-induced lipid peroxidation. In this study, we investigated the effect of edaravone on the myeloperoxidase (MPO) activity, an enzyme res
- Suh, Lindsey Y.K.,Babu, Dinesh,Tonoyan, Lusine,Reiz, Béla,Whittal, Randy,Tabatabaei-Dakhili, S. Amirhossein,Morgan, Andrew G.,Velázquez-Martínez, Carlos A.,Siraki, Arno G.
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p. 422 - 432
(2019/09/06)
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- Efficient Synthesis of α-Chloroketones Catalyzed by Fluorous Hydrazine-1,2-Bis(Carbothioate) Organocatalyst
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A novel and recoverable fluorous hydrazine-carbothioate organocatalyst was prepared. It could catalyze α-chlorination of alkyl ketones with N-chlorosuccinimide as chlorine source under mild reaction conditions. The reaction afforded the corresponding α-ch
- Zhu, Yi-Wei,Shi, Yi-Xin
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p. 570 - 574
(2016/03/01)
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- Geminal Dichlorination of Phenyliodonium Ylides of β-Dicarbonyl Compounds through Double Ligand Transfer from (Dichloroiodo)benzene
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Pre-formed phenyliodonium ylides of cyclic and acyclic β-diketones, β-keto esters and β-diesters were reacted with (dichloroiodo)benzene, resulting in transfer of both chloride ligands onto the ylidic carbon. These two hypervalent iodine(III) compounds exhibit high reactivity towards each other under mild reaction conditions and typically afford the gem-dichloride products in good yield. Upon comparison of these chlorination reactions with those of the analogous diazocarbonyl compounds, reactions of iodonium ylides were unilaterally faster, and often gave the products in higher yield.
- Tao, Jason,Tuck, Tina N.,Murphy, Graham K.
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supporting information
p. 772 - 782
(2016/03/01)
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- Characterization of a Cyanobacterial Haloperoxidase and Evaluation of its Biocatalytic Halogenation Potential
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Vanadium-dependent haloperoxidases (VHPOs) are a class of halogenating enzymes found in fungi, lichen, algae, and bacteria. We report the cloning, purification, and characterization of a functional VHPO from the cyanobacterium Acaryochloris marina (AmVHPO), including its structure determination by X-ray crystallography. Compared to other VHPOs, the AmVHPO features a unique set of disulfide bonds that stabilize the dodecameric assembly of the protein. Easy access by high-yield recombinant expression, as well as resistance towards organic solvents and temperature, together with a distinct halogenation reactivity, make this enzyme a promising starting point for the development of biocatalytic transformations.
- Frank, Annika,Seel, Catharina Julia,Groll, Michael,Gulder, Tanja
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p. 2028 - 2032
(2016/11/09)
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- Dichlorination of α-Diazo-β-dicarbonyls using (dichloroiodo)benzene
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Abstract α-Diazo-β-dicarbonyl compounds were chlorinated using (dichloro)iodobenzene and an activating catalyst. A broad range of reaction rates was observed, which paralleled the relative stability/nucleo-philicity of the diazo compounds. Acyclic diazocarbonyls reacted faster than cyclics, and β-diketones were much faster to react than β-keto esters or β-diesters. Lewis acid activation was used for the first time, allowing us to overcome instances of poor chemoselectivity. Though the yields ranged from low to good, this chlorination reaction has again proven a mild and effective halogenation strategy.
- Coffey, Keith E.,Murphy, Graham K.
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p. 1003 - 1007
(2015/05/20)
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- Trihaloisocyanuric acids as convenient reagents for regioselective halogenation of β-dicarbonyl compounds
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The reaction of β-dicarbonyl compounds (β-ketoesters and β-diketones) with 0.34 mol equiv of trichloro- and tribromoisocyanuric acids produced regioselectively the corresponding α-monohalo β-dicarbonyl compound. On the other hand, utilization of 0.68 mol equiv of the trihaloisocyanuric acid produced the α,α-dihalo β-dicarbonyl compound.
- Mendon?a, Gabriela F.,Sindra, Haryadylla C.,de Almeida, Leonardo S.,Esteves, Pierre M.,de Mattos, Marcio C.S.
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scheme or table
p. 473 - 475
(2009/05/07)
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- An efficacious method for the halogenation of β-dicarbonyl compounds under mildly acidic conditions
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A variety of 1,3-diketones, β-ketoesters and malonates can be chlorinated in high yields using sodium hypochlorite in a 5:2 mixture of acetone/acetic acid at 0°C for 1 h. Similarly, bromination of these dicarbonyl substrates can be accomplished under the same conditions using sodium hypobromite.
- Meketa, Matthew L.,Mahajan, Yogesh R.,Weinreb, Steven M.
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p. 4749 - 4751
(2007/10/03)
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- New Enzyme Models of Chloroperoxidase: Improved Stability and Catalytic Efficiency of Iron Porphyrinates Containing a Thiolato Ligand
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The heme-thiolate protein chloroperoxidase (CPO) catalyzes the chlorination of activated C-H bonds. A reaction mechanism is proposed for this enzymatic transformation (Scheme 1), and a new iron(III) porphyrinate complex 13 is synthesized containing pentafluorophenyl groups at two meso-positions and a thiophenolato ligand coordinating to the Fe-atom (Schemes 2 and 3). Due to the presence of the electron-withdrawing substituents, the catalyst 13 is appreciably resistant to oxidants (HOCl) and chlorinates, e.g., monochlorodimedone (5), with turnover numbers up to 1530. The redox potential of 13, E0 = - 134 mV, and the Soret band (λmax 448 nm) of the CO adduct of the reduced state of 13 are close to the corresponding values of the enzyme CPO.
- Wagenknecht, Hans-Achim,Claude, Cécile,Woggon, Wolf-Dietrich
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p. 1506 - 1520
(2007/10/03)
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- A New Reaction of α-Chloro-α-chlorosulfenyl Ketones: Facile Syntheses of 3,3-Dichloro- and 3-Chloro-Chroman-4-ones and Thiochroman-4-ones
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3-Chloro-3-chlorosulfenylchroman-4-ones are efficiently obtained from chroman-4-ones by treatment with thionyl chloride.Direct oxidation affords 3,3-dichlorochroman-4-ones, whilst conversion to the sulfenamides prior to oxidation provides a facile route to 3-chlorochroman-4-ones.
- Gabbutt, Christopher D.,Hepworth, John D.,Heron, B. Mark
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p. 5245 - 5254
(2007/10/02)
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- CHLORINATING PROPERTIES OF THE TRIMETHYLCHLOROSILANE-POTASSIUM BROMATE-DMF SYSTEM
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β-Dicarbonyl compounds such as ethyl acetoacetate, dimedone, and Meldrum's acid derivatives undergo monochlorination by the action of a mixture of ClSiMe3 and KBrO3 in DMF at ca. 20 deg C. Keywords: β-dicarbonyl compounds, monochlorination.
- Zav'yalov, S. I.,Sitkareva, I. V.,Ezhova, G. I
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p. 356 - 358
(2007/10/02)
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- POLYMERS AS REAGENTS AND CATALYSTS. PART X. HALOGENATIONS OF ACETOPHENONE AND 1,3-DIKETONES WITH POLYMER-SUPPORTED REAGENTS.
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A crosslinked copolymer of styrene and 4-vinylpyridine (40-43percent of monomer units) was reacted with hydrogen iodide to give a polymer containing pyridinium iodide residues.Reaction of this with chlorine in chloroform at 0 deg C gave a polymer containing pyridinium tetrachloroiodate residues.In a similar manner but using methyl iodide in place of hydrogen iodide, crosslinked polymers containing N-methylpyridinium iodide and N-methylpyridinium tetrachloroiodate residues were prepared.The latter contained up to three chlorine molecules per iodine atom.Both reagents reacted with acetophenone, thus forming iodomethyl-phenyl ketone (4) and ch loromethyl-phenyl ketone (5), the ratios depending on the reagent used and the reaction time.Chlorinations of 5,5-dimethyl cyclohexane-1,3-dione and indane-1,3-dione with polymer-supported reagent (2) resulted in the formation of geminal dichlorides in high yields.
- Sket, Boris,Zupan, Marko
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p. 2865 - 2870
(2007/10/02)
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- Reactions of Dimedone with Sulfur Chlorides
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A comparative study of the reactions of dimedone (1), as a representative β-diketone, with various simple sulfur chlorides has revealed that the product distribution observed can best be accounted for in terms of competing mechanisms of oxygen attack or carbon attack (at C-2) in the enol form.Oxygen attack is particularly important with SCl2 and S2Cl2 and appears to involve a subsequent intramolecular transfer of Cl (or ClS) to C-2, via an intermediate such as 12.The relative electrophilicity of the reagents and the facility with which 12 can be expected to rearrange to a C-2 substituted product appear to be among the factors influencing the course of these reactions.Some of the reactions show promise as synthetic routes to potentially useful dimedone derivatives.
- Still, Ian W. J.,Kutney, Gerald W.
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p. 4911 - 4914
(2007/10/02)
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