- Altering 2-Hydroxybiphenyl 3-Monooxygenase Regioselectivity by Protein Engineering for the Production of a New Antioxidant
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2-Hydroxybiphenyl 3-monooxygenase is a flavin-containing NADH-dependent aromatic hydroxylase that oxidizes a broad range of 2-substituted phenols. In order to modulate its activity and selectivity, several residues in the active site pocket were investigated by saturation mutagenesis. Variant M321A demonstrated altered regioselectivity by oxidizing 3-hydroxybiphenyl for the first time, thus enabling the production of a new antioxidant, 3,4-dihydroxybiphenyl, with similar ferric reducing capacity to the well-studied piceatannol. The crystal structure of M321A was determined (2.78 ?), and molecular docking of the 3-substituted phenol provided a rational explanation for the altered regioselectivity. Furthermore, HbpA was found to possess pro-S enantioselectivity towards the production of several chiral sulfoxides, whereas variant M321F exhibited improved enantioselectivity. Based on the biochemical characterization of several mutants, it was suggested that Trp97 stabilized the substrate in the active site, Met223 was involved in NADH entrance or binding to the active site, and Pro320 might facilitate FAD movement.
- Bregman-Cohen, Almog,Deri, Batel,Maimon, Shiran,Pazy, Yael,Fishman, Ayelet
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p. 583 - 590
(2018/02/13)
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- Synthesis of α-oxygenated ketones and substituted catechols via the rearrangement of N-enoxy- and N-aryloxyphthalimides
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A common approach to the synthesis of α-oxygenated carbonyl compounds and catechols is the treatment of a carbonyl compound or a phenol with an electrophilic oxygen source. As an alternative approach to these important structures, formal [3,3]-rearrangements of N-enoxyphthalimides, N-enoxyisoindolinones, and N-aryloxyphthalimides have been explored. When used in combination with an initial Chan-Lam coupling, these transformations facilitate the dioxygenation of alkenylboronic acids for the synthesis of α-oxygenated ketones and the dioxygenation of arylboronic acids for the synthesis of catechols. The rearrangements of N-enoxyisoindolinones have also been shown to be diastereoselective.
- Kroc, Michelle A.,Patil, Aditi,Carlos, Anthony,Ballantine, Josiah,Aguilar, Stephanie,Mo, Dong-Liang,Wang, Heng-Yen,Mueller, Daniel S.,Wink, Donald J.,Anderson, Laura L.
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p. 4125 - 4137
(2017/06/29)
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- Conversion of Simple Cyclohexanones into Catechols
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A novel I2-catalyzed direct conversion of cyclohexanones to substituted catechols under mild and simple conditions has been described. This novel transformation is remarkable with the multiple oxygenation and dehydrogenative aromatization processes enabled just by using DMSO as the solvent, oxidant, and oxygen source. This metal-free and simple system demonstrates a versatile protocol for the synthesis of highly valuable substituted catechols and therefore streamlines the synthesis and modification of biologically important molecules for drug discovery.
- Liang, Yu-Feng,Li, Xinyao,Wang, Xiaoyang,Zou, Miancheng,Tang, Conghui,Liang, Yujie,Song, Song,Jiao, Ning
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supporting information
p. 12271 - 12277
(2016/09/28)
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- A Catalyst-Controlled Aerobic Coupling of ortho-Quinones and Phenols Applied to the Synthesis of Aryl Ethers
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ortho-Quinones are underutilized six-carbon-atom building blocks. We herein describe an approach for controlling their reactivity with copper that gives rise to a catalytic aerobic cross-coupling with phenols. The resulting aryl ethers are generated in high yield across a broad substrate scope under mild conditions. This method represents a unique example where the covalent modification of an ortho-quinone is catalyzed by a transition metal, creating new opportunities for their utilization in synthesis.
- Huang, Zheng,Lumb, Jean-Philip
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supporting information
p. 11543 - 11547
(2016/11/17)
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- Synthesis of catechols from phenols via Pd-catalyzed silanol-directed C-H oxygenation
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A silanol-directed, Pd-catalyzed C-H oxygenation of phenols into catechols is presented. This method is highly site selective and general, as it allows for oxygenation of not only electron-neutral but also electron-poor phenols. This method operates via a silanol-directed acetoxylation, followed by a subsequent acid-catalyzed cyclization reaction into a cyclic silicon-protected catechol. A routine desilylation of the silacyle with TBAF uncovers the catechol product.
- Huang, Chunhui,Ghavtadze, Nugzar,Chattopadhyay, Buddhadeb,Gevorgyan, Vladimir
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p. 17630 - 17633
(2011/12/16)
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- NOVEL DXR INHIBITORS FOR ANTIMICROBIAL THERAPY
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The present invention generally concerns particular methods and compositions for antimicrobial therapy. In particuarl embodiments, the compositions target DXR. In specific embodiments, the compositions are electron-deficient heterocyclic rings.
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Page/Page column 68; 70; 72
(2011/05/05)
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- Synthesis, activity and molecular modeling of a new series of chromones as low molecular weight protein tyrosine phosphatase inhibitors
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Protein tyrosine phosphatases (PTP) are crucial elements in eukaryotic signal transduction. Several reports suggested that the LMW-PTP family has oncogenic relevance. Moreover, LMW-PTP has been recognized as a negative regulator of insulin-mediated mitotic and metabolic signaling. Thus, inhibition of the LMW-PTP can be considered an attractive approach for the design of new therapeutic agents for the treatment of type II diabetes and for new antitumoral drugs. To date very few (and weak) inhibitors of LMW-PTP have been identified. On the basis of the reported weak activity of some flavonoids on phosphatases, we discovered a lead that originated a new class of highly active LMW-PTP inhibitors; these compounds inhibit also PTP-1B and are active in cellular assays. Docking experiments and SAR highlighted the possible binding mode of these compounds to the enzyme, putting the background for the future optimization of their inhibitory activity and selectivity towards the closely related enzyme PTP-1B.
- Forghieri, Marco,Laggner, Christian,Paoli, Paolo,Langer, Thierry,Manao, Giampaolo,Camici, Guido,Bondioli, Lucia,Prati, Fabio,Costantino, Luca
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experimental part
p. 2658 - 2672
(2009/09/08)
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- Coordination chemistry based approach to lipophilic inhibitors of 1-deoxy-D-xylulose-5-phosphate reductoisomerase
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1-Deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) in the non-mevalonate pathway found in most bacteria is a validated anti-infective drug target. Fosmidomycin, a potent DXR inhibitor, is active against Gram-negative bacteria. A coordination chemistry and structure based approach was used to discover a novel, lipophilic DXR inhibitor with an IC50 of 1.4 μM. It exhibited a broad spectrum of activity against Gram-negative and -positive bacteria with minimal inhibition concentrations of 20-100 μM (or 3.7-19 μg/mL).
- Deng, Lisheng,Sundriyal, Sandeep,Rubio, Valentina,Shi, Zheng-Zheng,Song, Yongcheng
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supporting information; experimental part
p. 6539 - 6542
(2010/04/04)
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- Synthesis of chlorinated and non-chlorinated biphenyl-2,3- and 3,4-catechols and their [2H3]-isotopomers
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A synthetic scheme is described for chlorinated biphenyl-2,3- and 3,4-catechols to be used as standards for structural assignment of metabolites and protein adducts of 2,2′,5,5′-tetrachlorobiphenyl in which both rings retain chlorine substituents. The scheme has general applicability to the synthesis of chlorinated biphenyl catechols. Dimethyl catechol ethers are coupled to dichloroaniline via the Cadogan reaction to give a library of isomers, followed by demethylation of the ethers with BBr3 to yield the target catechols. Separation of pure isomers is accomplished by TLC or HPLC prior to or following demethylation, depending on the isomer mixture. [ 2H3]-Isotopomers are generated using 2,5-dichloroaniline- d3 as the starting arylamine in the coupling reaction. The dichloroaniline-d3 hydrochloride is obtained as the sole product from nitration of p-dichlorobenzene-d4 followed by Pd/C-catalyzed hydrogenation under strongly acidic conditions. This hydrogenation procedure provides a simple and convenient approach to selective reduction of aryl nitro groups in the presence of halogen ring substituents.
- Lin, Po-Hsiung,Sangaiah,Ranasinghe, Asoka,Ball, Louise M.,Swenberg, James A.,Gold, Avram
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p. 2624 - 2629
(2007/10/03)
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- Complex induced proximity effect enhancement in α-silyl carbanion generation. A general conversion of 2-silyl benzamides into 2-fluorosilylacetophenones
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LDA treatment of 2-silylated benzamides 1 affords 2-fluorosilylated acetophenones 3 in a general process likely driven by CIPE-facilitated α-silyl carbanion formation and rearrangement; oxidation (H2O2) of the products given 2-hydroxyacetophenones and catechols.
- Brough, Paul A.,Fisher, Stephen,Zhao, Baoping,Thomas, Ryan C.,Snieckus, Victor
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p. 2915 - 2918
(2007/10/03)
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- Comparison of Substituted 2-Nitrophenol Degradation by Enzyme Extracts and Intact Cells
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The first catabolic pathway enzyme, nitrophenol oxygenase, transforms o-nitrophenol (ONP) to catechol. Thirteen of 16 substituted nitrophenols tested were actively transformed by both enzyme preparations and intact cells yielding a wide range of Km (Ks) and Vmax. Individual chemicals in binary mixtures demonstrated competitive inhibition. Chemical and physical characteristics (electron withdrawal, size, and position of substitution on the 2-nitrophenol ring) affected degradation kinetics. The strongest correlation were between Km or Vmax values and electron withdrawal, though there was also evidence for effects relating to position and size of substitution on the aromatic ring. Kinetic parameters determined for enzyme preparations did not correlate to those determined for intact cells. Though enzyme reactivity ultimately determined whether a given chemical would be transformed, the transformation by intact cells was apparently affected by factors other than those directly impacting the initial catabolic enzyme.
- Folsom, Brian R.,Stierli, Ruth,Schwarzenbach, Rene P.,Zeyer, Josef
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p. 306 - 311
(2007/10/03)
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- A new entry to the synthesis of 1,2-benzenediol congeners
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1,2-Benzenediols were synthesized via 1,1-bis(ethylthio)-3-cyclohexen-2-one derivatives, which were prepared by condensation of 1,1-bis(ethylthio)-2-propanone with Mannich bases. Regioselective preparation of their monoethers was also achieved.
- Ozaki,Oshio,Ohsuga,Kaburagi,Sung,Kim
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p. 1132 - 1136
(2007/10/02)
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- A NEW ENTRY TO 1,2-BENZENEDIOL CONGENERS
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1,2-Benzenediols and their monoethers were efficiently prepared from α,α-bis(ethylthio)cyclohexenones which were constructed by the C3+C3 annulation of 1,1-bis(ethylthio)propan-2-one and the Mannich bases. KEYWORDS 1,2-benzenediol; aromatic synthesis; annulation; aromatic compound; acetal
- Ozaki, Yutaka,Oshio, Ikumi,Kim, Sang-Won
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p. 1434 - 1436
(2007/10/02)
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