- Chiroptical switching behavior of heteroleptic ruthenium complexes bearing acetylacetonato and tropolonato ligands
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Four types of tris-chelate ruthenium complexes bearing acetylacetonato (acac) and tropolonato (trop) ligands were synthesized and optically resolved into Δ and Λ isomers: [Ru(acac)3] (Ru-0), [Ru(acac)2(trop)] (Ru-1), [Ru(acac)(trop)2] (Ru-2), and [Ru(trop)3] (Ru-3). Chiral HPLC chromatograms, electronic circular dichroism (ECD), and vibrational circular dichroism (VCD) of the four ruthenium complexes were systematically investigated. As a result, the absolute configurations of the newly prepared enantiomeric complexes Ru-2 and Ru-3 were determined. For the case of Ru-2, its absolute configuration was also confirmed by single crystal X-ray diffraction analysis. The ECD changes upon chemical oxidation were further investigated for the four complexes. An ECD change in enantiomeric Ru-1 was observed upon oxidation, but the oxidized species soon returned to the neutral state within a few minutes. Enantiomers of Ru-3 also showed explicit ECD changes upon oxidation. Further, the lifetime of the oxidized state was the longest among the four investigated complexes, whereas they racemized in solution at room temperature. In contrast, the enantiomers of heteroleptic complexes (Ru-1 and Ru-2) concurrently exhibited ECD changes, relatively long lifetime of the oxidized state, and nil or quite slow racemization behavior. The coexistence of acac and trop ligands was key to making the competing factors compatible in the resultant ruthenium complexes.
- Sato, Hisako,Tateyama, Kazunori,Yamazaki, Kana,Yoshida, Jun,Yuge, Hidetaka
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p. 14611 - 14617
(2021/11/04)
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- Synthesis, structure-activity relationships, and mechanistic studies of 5-arylazo-tropolone derivatives as novel xanthine oxidase (XO) inhibitors
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Xanthine oxidase (XO) is an enzyme that contains molybdenum at the active site and catalyzes the oxidation of purine bases to uric acid. Even though XO inhibitors are widely used for the treatment of hyperuricemia and gout, only very few such compounds are clinically used as drugs for the treatment of these diseases. Given the unique physicochemical properties of tropolone, i.e., its chelating effect and the pKa value that is similar to that of carboxylic acid, we have synthesized 22 5-arylazotropolone derivatives as potential XO inhibitors. In vitro enzyme-inhibitory assays for XO revealed that 3-nitro derivative 1j showed the most potent XO inhibitory activity, which is by one order of magnitude more potent than allopurinol. An enzyme-kinetic study revealed that 1j inhibited the production of uric acid by XO both competitively and non-competitively. A docking-simulation study of 1j with XO suggested that the carbonyl and hydroxyl groups of the tropolone ring interact with the hydroxy group that acts as a ligand for molybdenum and the amino acid residues around the active site of XO.
- Sato, Daisuke,Kisen, Takuya,Kumagai, Mina,Ohta, Kiminori
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p. 536 - 542
(2017/12/29)
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- Investigation of self-immolative linkers in the design of hydrogen peroxide activated metalloprotein inhibitors
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A series of self-immolative boronic ester protected methyl salicylates and metal-binding groups with various linking strategies have been investigated for their use in the design of matrix metalloproteinase proinhibitors.
- Jourden, Jody L. Major,Daniel, Kevin B.,Cohen, Seth M.
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supporting information; experimental part
p. 7968 - 7970
(2011/08/07)
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- STIMULUS-TRIGGERED PRODRUGS
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Set forth herein, inter alia, are compositions and methods for treating diseases with prodrugs. Provided herein are prodrug compositions for inhibiting the function of proteins, compositions and methods for treating diseases associated with oxidative compounds, oxidatively-sensitive prodrugs of inhibitors of metalloproteases. and methods of inhibiting metalloproteases using oxidatively-sensitive prodrugs.
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Page/Page column 54-56
(2012/01/13)
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- Evidence from mechanistic probes for distinct hydroperoxide rearrangement mechanisms in the intradiol and extradiol catechol dioxygenases
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Three mechanistic probes were used to investigate whether the Criegee rearrangement step of catechol 1,2-dioxygenase (CatA) from Acinetobacter sp. proceeds via a direct 1,2-acyl migration, via homolytic O-O cleavage, or via a benzene oxide-oxepin rearrangement. Incubation of CatA with 3- chloroperoxybenzoic acid led to the formation of a 9:1 mixture of 2-chlorophenol and 3-chlorophenol, via a mechanism involving O-O homolytic cleavage. Incubation of CatA with 2-hydroperoxy-2-methylcyclohexanone led to formation of 5,6-diketoheptan-1-ol, also consistent with an O-O homolytic cleavage mechanism, and not consistent with a direct 1,2-acyl migration. No reaction product was isolated from incubation of CatA with 6-hydroxymethyl-6-methylcyclohexa-2,4- dienone, an analogue that is able to undergo the benzene oxide-oxepin rearrangement, but not able to undergo O-O homolytic cleavage. In contrast, incubation of extradiol dioxygenase MhpB from Escherichia coli with 6-hydroxymethyl-6-methylcyclohexa2,4-dienone led to the formation of a 2-tropolone ring expansion product, consistent with a direct 1,2-alkenyl migration for extradiol cleavage. Taken together, the results imply different mechanisms for the Criegee rearrangement steps of intradiol and extradiol catechol dioxygenases: a direct 1,2-alkenyl migration for extradiol cleavage and an O-O homolytic cleavage mechanism for intradiol cleavage.
- Xin, Meite,Bugg, Timothy D. H.
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experimental part
p. 10422 - 10430
(2009/02/04)
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- Syntheses of novel 1,3-diazaazulene derivatives and their nonlinear optical characterization
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We have synthesized three new 1,3-diazaazulene derivatives, namely, 2-(4′-N,N-dimethylaminophenyl)-6-nitro-1,3-diazaazulene (18, DMAPNA), 2-(4′-aminophenyl)-6-nitro-1,3-diazaazulene (19, APNA) and 2-[4′-N-(2-hydroxyethyl)aminophenyl]-6-nitro-1,3-diazaazulene (20, HEAPNA), each of them contains an amino substitute as the electron donor (D), 2-phenyl-1,3-diazaazulene as the π-conjugated bridge and a nitro as the electron acceptor (A). Our theoretical results have predicted that these D-π-A type chromophores possess low ground-state dipole moment (μg) and large first-order hyperpolarizability (β), which may facilitate a low degree of aggregation for the chromophores dispersed in a polymeric matrix as well as a large nonlinear optical (NLO) response. The expected NLO performance has been confirmed by the experimental β and μg values, e.g., for 18, 407.8 × 10-30 esu and 4.7 D, respectively. The origins of large β and low μg are explained in terms of a two-state quantum model. The DMAPNA (18)-doped and poled polymethylmethacrylate film exhibits a large second harmonic generation (SHG) coefficient of d33 = 10.9 pm V-1 with excellent thermal stability (above 70% of the maximal SHG coefficient remains at ~100 °C). The Royal Society of Chemistry.
- Zhu, Yun-Ji,Qin, An-Jun,Fu, Li-Min,Ai, Xi-Cheng,Guo, Zhi-Xin,Zhang, Jian-Ping,Ye, Cheng
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p. 2101 - 2106
(2008/02/07)
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- Fungicidal activity of β-thujaplicin analogues
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The fungicidal activity of analogues of β-thujaplicin, a natural product responsible for the durability of heartwood of several cupressaceous trees, was investigated in vitro on the growth of different white and brown rot fungi involved in wood biodegradation, Coriolus versicolor, Phanerochaete chrysosporium, Poria placenta and Gloephyllum trabeum. The study shows that 2-hydroxycyclohepta-2,4,6-trienone (tropolone), easily prepared according to a literature procedure, possesses interesting fungicidal activity when compared to β-thujaplicin, azaconazole, tebuconazole and copper oxine, which suggests this compound should be examined further as a potential biocide for wood preservation.
- Baya, Mounir,Soulounganga, Patrice,Gelhaye, Eric,Grardin, Philippe
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p. 833 - 838
(2007/10/03)
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- Stereo- and regiocontrolled hydroxylation of oxyallyl [4+3] cycloadducts. A concise synthesis of hinokitiol
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Stereo- and regioselective hydroxylation of 8-oxabicyclo[3.2.1]oct-6-en-3-ones was achieved by the action of (diacetoxyiodo)benzene in methanolic potassium hydroxide (the Moriarty oxidation). Subsequent double elimination afforded a convenient preparation of substituted tropolones, as exemplified in a three-step synthesis of hinokitiol (1).
- Lee, Jae Chol,Cho, Sung Yun,Cha, Jin Kun
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p. 7675 - 7678
(2007/10/03)
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- Electrochemical methoxylation of 1,2,3-trisubstituted azulenes
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1,2,3-Trisubstituted azulene analogs 6a and 6b easily underwent methoxylation in position 4 or 6 of an azulene ring via an electrochemical oxidation. It is a simple, convenient and selective method for introducing a methoxy group into a 7-membered ring of azulene analogs when compared with traditional chemical methods. It could be useful in preparing 2,4- and 2,6-azuloquinone analogs.
- Chen, Arh-Hwang
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- Chromogenic substrate to peroxidase enzymes
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A novel chromogenic substrate to peroxidase enzymes is provided which is comprised of a mixture of an adduct formed from a hydrozone and a dienophile, and an aromatic nucleophile. The mixture undergos an oxidative coupling in the presence of peroxidase enzymes and peroxides forming a purple indamine dye. The mixture is also stable and unaffected by oxygen of the air or by hydrogen peroxide.
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- Synthesis and reactions of 2,3-dihydrocyclohepta[b][1,4]-thiazines and 2,3-dihydro-1H-cyclohepta[b]pyrazines
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The reaction of 2-methoxytropone with ethylenediamine gave 2-(2-aminoethyl)aminotropone and 2,2′-(1,2-ethanediamino)-bis(tropone), and the former afforded 2,3-dihydro-1H-cyclohepta[b]pyrazine (13) on heating. N-Methyl compound 14 of 13 was also obtained by the similar method. 14 was led to the dimethyl cation 18b, which gave exclusively 7-bromo compound 24 with bromine in acetic acid. 18b and 24 rearranged to 1,2,3,4-tetrahydro-1, 4-dimethylquinoxaline-6-carbaldehyde with alkali, while 13 rearranged to 1-phenylimidazolin-2-one on treatment with H2O2. The reaction of 2-chlorotropone with 2-aminoethanethiol rapidly afforded 2-(2-aminoethylthio)tropone (35a), which gradually changed to 2-[2-(2-troponyl)thioethylamino]tropone (37a) and N,N′-bis(2-troponyl)-2-aminoethanedisulfide (39a) via unstable 2-(2-mercaptoethyl)-aminotropone (38a). Hydrochloride of 35a gave, upon heating, 2, 3-dihydrocyclohepta[b] [1,4]thiazine (15), which gave N-methyl cation 40 on treatment with magic methyl. 40 gradually changed with cold alkali to the disulfide 39b, via 35b, 37b, and 38b, in a manner similar to the case of their parent compounds (35a, 37a, and 38a). Possible pathways of these reactions, especially the facile exchange of the difunctionalized side-chains, are discussed.
- Nozoe, Tetsuo,Ishikawa, Sumio,Shindo, Kimio
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p. 733 - 744
(2007/10/02)
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- Thermally-induced Radical Rearrangement of 2-(2-Thienylmethoxy)- and 2-(2-Benzothienylmethoxy)tropones
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Upon heating at ca. 160 deg C, 2-(2-thienylmethoxy)tropone afforded 3- and 5-(2-thienylmethyl)tropolones.Formation of 3,5-bis(2-thienylmethyl)tropolone and unsubstituted tropolone indicated a radical chain mechanism for the thermolysis.
- Takeshita, Hitoshi,Mametsuka, Hiroaki,Motomura, Hideshi
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p. 1211 - 1214
(2007/10/02)
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- Stereospecific trans-elimination of 2-alkoxy- and 2-cycloalkoxytropones to alkenes and cycloalkenes
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The title compounds undergo thermal fragmentation to tropolones and alkenes and cycloalkenes.Product distribution and kinetic analyses of specifically labelled deuterio compounds establish the process to be a concerted electrocyclic reaction.
- Takeshita, Hitoshi,Mametsuka, Hiroaki
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p. 2035 - 2040
(2007/10/02)
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- THERMAL REARRANGEMENT OF 2-(2-FURYLMETHOXY)TROPONES
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Furfuryl ethers of tropolone and 4- and 5-isopropyltropolones afforded 3-(2-methyl-3-furyl)- 3-(2-furylmethyl)-, 5-(2-furylmethyl-, and 5-(5-methyl-2-furyl)tropolone derivatives.Although most of the thermolysates were structurally indistinguishable to the 3,3- or 5,5-sigmatropic products, the deuterium-labelling experiment proved all the pyrolysates to be intermolecular reaction products.
- Takeshita, Hitoshi,Mametsuka, Hiroaki
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p. 663 - 666
(2007/10/02)
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- A New Stereospecific trans-Elimination of 2-Alkoxy- and 2-Cycloalkoxytropones to Alkenes and Cycloalkenes: the first Verification of the s8? + a2? + s2?> Process
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Solutions of 2-alkoxy- and 2-cycloalkoxy-tropones were heated to give alkenes and cycloalkenes respectively, without skeletal rearrangement, in good yields; deuterium labelling studies confirmed a stereospecific trans-elimination, in a s8? + a2? + s2?> mode, with an interesting isotope effect and a large rate retardation.
- Takeshita, Hitoshi,Mametsuka, Hiroaki
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p. 483 - 484
(2007/10/02)
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- A Dimethyl Sulfoxide-mediated Oxidation of Arylalkyl and Alkyl Alcohols to Corresponding Aldehydes and Ketones via Tropolonyl Ethers
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The arylmethyl and diarylmethyl ethers of tropolones were oxidized to the corresponding carbonyl derivatives by heating in dimethyl sulfoxide.The free alcohols were oxidized at a much slower rate, suggesting that some sort of DMSO-linked intermediates are responsible for the oxidation.Inertness of free alcohols was proven by means of the cross-over experiments, including deuterium-labelling.This oxidation was applicable to alkyl ethers, but not to alkenyl ethers, which are known to cause the Claisen-rearrangement.
- Takeshita, Hitoshi,Mametsuka, Hiroaki,Matsuo, Norihide
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p. 1137 - 1139
(2007/10/02)
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- A THERMALLY-INDUCED RADICAL REARRANGEMENT OF 2-ARYLMETHOXYTROPONES TO 3- AND 5-ARYLMETHYLTROPOLONES
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2-Arylmethoxytropones, i.e., 2-benzyloxytropone, 2-(p-tolylmethoxy)tropone, 2-(4-bromophenylmethoxy)tropone, 2-(4-chlorophenylmethoxy)tropone, 2-(4-methoxyphenylmethoxy)tropone, and 2-(1-naphthylmethoxy)tropone, rearranged upon heating to the 3- and 5-arylmethyltropolones via the radical intermediates.Similarly, 5-bromo-2-(p-tolylmethoxy)tropone gave 5-bromo-3-(p-tolylmethyl)tropolone.
- Takeshita, Hitoshi,Mametsuka, Hiroaki,Chisaka, Atsuko,Matsuo, Norihide
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