- Cobalt porphyrins immobilized on polymer microspheres as catalysts for the oxidation of 2-naphthol to 2-hydroxy-1,4-naphthoquinone by molecular oxygen
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Three types of porous polymer microspheres immobilized with cobalt porphyrins appending p-H, p-Cl and p-NO2 phenyl substituents (designated as CoPP-GMA/MMA, CoCPP-GMA/MMA and CoNPP-GMA/MMA, respectively) were prepared. Their catalytic activities on the oxidation of 2-naphthol to 2-hydroxy-1,4-naphthoquinone by molecular oxygen were investigated in alkaline methanol. The experimental results showed that the porous microsphere supported cobalt porphyrin catalysts could effectively activate molecular oxygen, and 2-naphthol was selectively oxidized to 2-hydroxy-1,4-naphthoquinone with high conversion in alkaline methanol. A phenomenon of distance-dependent catalytic activity was observed and a critical distance of 3.8 nm between porphyrins was determined for the porous polymer microsphere supported catalyst. More interestingly, the activity of the recycled catalyst increased gradually with the increased times of reuse. These results may be helpful in designing highly efficient metalloporphyrin catalysts. Graphical Abstract: The catalytic oxidation of 2-naphthol to 2-hydroxy-1,4-naphthoquinone (HNQ) by molecular oxygen was performed in alkaline methanol using supported cobaltporphyrin as catalyst.[Figure not available: see fulltext.]
- Zhao, Jing,Gao, Bao-Jiao,Gong, Yong-Kuan
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- Rhodium(II)-catalyzed reaction of 1,3-bis(diazo)indan-2-one with alcohols: Formation of unexpected 1,1-dialkoxy ketones
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The rhodium(II)-catalyzed decomposition of 1,3-bis(diazo)indan-2-one (1) in boiling dichloromethane containing primary alcohols gave 1,1-dialkoxyindan-2-ones (2) in good yields without any formation of 1,3-dialkoxy derivatives.
- Murata, Shigeru,Kongou, Chiharu,Tomioka, Hideo
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- Study of methanol catalyzed reaction between sodium 1,2-naphthoquine-4-sulfonate and hydroxyl ion and its application in the determination of methanol
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A novel and simple spectrophotometric method for the direct determination of methanol with 1,2-naphthoquinone-4-sulfonate (NQS) is developed in this paper. It is based on the fact that methanol can catalyze the reaction between 1,2-naphthoquinone-4-sulfonate and hydroxyl ion to form 2-hydroxy-1,4-naphthoquinone in buffer solution of pH 13.00. Beer's law is obeyed in a range of 0.26-15.8 mg/ml at the maximal absorption wavelength of 454 nm. The equation of linear regression is A = 0.01998 + 0.05944C (mg/ml), with a linear regression correlation coefficient of 0.9977. The detection limit is 0.25 mg/ml (3σ/k), while R.S.D. is 2.0% and the recovery rate is in a range of 96.5-103%. The detailed mechanism for the formation of the products is proposed and discussed.
- Li, Quanmin,Zhang, Huanhuan
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- Isoxazoles. 10. Degradation and enolization kinetics of 4- aminoisoxazolyl-1,2-naphthoquinone in basic aqueous solution
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The kinetics of enolization and degradation of N-(5-methyl-4-isoxazolyl)- 4-amino-1,2-naphthoquinone (1) was investigated in aqueous solutions over a pH range of 7.30 to 12.25, at 35 °C and at constant ionic strength (μ = 0.5) using reversed-phase HPLC. Pseudo-first-order kinetics was observed throughout the pH range studied. The rate of enolization (k(e)), the keto- enol equilibrium constant (K(t)), and specific base catalysis rate constant (k(OH)) were determined. Good agreement between the theoretical pH-rate profile and the experimental data supports the proposed transformation process. The average recovery for 1 and its tautomerization product 2- hydroxy-N-(5-methyl-4-isoxazolyl)-1,4-naphthoquinone 4-imine (2) from mixtures of different composition was evaluated.
- Ortiz,De Bertorello
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- Synthesis and characterization of new naphthoquinonic derivatives containing the pyrazole ring: Pyrazolylnaphthoquinones
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The reaction of 3-aminopyrazole (1) with 1,2-naphthoquinone-4-sulfonic acid sodium salt (2) was studied in different aqueous media. The novel pyrazolylnaphthoquinones synthesized were physical and spectroscopically characterized, including 2D NMR spectros
- Sperandeo, Norma R.,De Bertorello, Maria M.
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- Isoxazoles. 9. Degradation kinetics of 4-(isoxazolylamino)-1,2- naphthoquinone in acidic aqueous solution
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The degradation kinetics of N-(5-methyl-4-isoxazolyl)-4-amino-1,2- naphthoquinone (1) was studied in aqueous solution over a pH range of 0.65- 7.50, at 35 °C and at a constant ionic strength of 0.5. The degradation rates were determined by high-pressure liquid chromatography and were observed to follow pseudo-first-order kinetics with respect to the concentration of 1. The pH-rate profile was linear with slope -1 under acidic pH, becoming pH independent from 3.50 to 7.50. Good agreement between the theoretical pH-rate profile and the experimental data supports the proposed degradation process. The catalytic rate constants for hydrogen ion and water were k(H) = 0.901 M-1 h-1 and k(o) = 1.34 x 10-3 h-1, respectively. These data are appropriate to develop a stable dosage form of 1. The accuracy, peak sharpness, and asymmetry factor for the analytical method were determined.
- Ortiz,De Bertorello
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- EXEMPLE DE REACTION A L'INTERFACE SOLIDE-LIQUIDE : OXYDATION DE NAPHTALENEDIOLS PAR LE SUPEROXYDE DE POTASSIUM
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The oxidation of 1,2 and 1,3-dihydroxynaphthalenes with potassium superoxide in aprotic media is a heterogeneous reaction at the solid-liquid interface, leading to the 2-hydroxy-1,4-naphthoquinone with good yields even if the addition of crown-ether is omitted.
- Vidril-Robert, Daniele,Maurette, Marie-Therese,Oliveros, Esther,Hocquaux, Michel,Jacquet, Bernard
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- Menadione structure-based novel coronavirus 3CL protease inhibitor
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The invention discloses a menadione derivative capable of resisting novel coronavirus and medical application of the menadione derivative. The structure of the compound is shown as a formula (I), in the formula, R is a hydrogen atom, methyl, acetyl or hydroxyl, and R1 is hydrogen, methoxy, benzyloxy or benzoyloxy. The compound disclosed by the invention can inhibit the 3CL hydrolase of the 2019-nCoV novel coronavirus, and has the activity of resisting the novel coronavirus. In-vitro activity determination experiments show that the enzyme inhibition rate of part of the compounds reaches 90% or above under the concentration of 1 [mu] M, and is significantly superior to that of a positive control drug alkannin. Cell-level toxicity test experiment results show that the toxicity of menadione and the derivative thereof to host normal cells HSF is significantly lower than that of positive drugs alkannin and juglone, and part of the compounds show relatively strong anti-novel coronavirus activity in vitro, and have an important significance for the development of high-efficiency and low-toxicity new anti-novel coronavirus drugs.
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Paragraph 0036-0039
(2021/04/14)
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- Discovery of juglone and its derivatives as potent SARS-CoV-2 main proteinase inhibitors
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SARS-CoV-2 as a positive-sense single-stranded RNA coronavirus caused the global outbreak of COVID-19. The main protease (Mpro) of the virus as the major enzyme processing viral polyproteins contributed to the replication and transcription of SARS-CoV-2 in host cells, and has been characterized as an attractive target in drug discovery. Herein, a set of 1,4-naphthoquinones with juglone skeleton were prepared and evaluated for the inhibitory efficacy against SARS-CoV-2 Mpro. More than half of the tested naphthoquinones could effectively inhibit the target enzyme with an inhibition rate of more than 90% at the concentration of 10 μM. In the structure-activity relationships (SARs) analysis, the characteristics of substituents and their position on juglone core scaffold were recognized as key ingredients for enzyme inhibitory activity. The most active compound, 2-acetyl-8-methoxy-1,4-naphthoquinone (15), which exhibited much higher potency in enzyme inhibitions than shikonin as the positive control, displayed an IC50 value of 72.07 ± 4.84 nM towards Mpro-mediated hydrolysis of the fluorescently labeled peptide. It fit well into the active site cavity of the enzyme by forming hydrogen bonds with adjacent amino acid residues in molecular docking studies. The results from in vitro antiviral activity evaluation demonstrated that the most potent Mpro inhibitor could significantly suppress the replication of SARS-CoV-2 in Vero E6 cells within the low micromolar concentrations, with its EC50 value of about 4.55 μM. It was non-toxic towards the host Vero E6 cells under tested concentrations. The present research work implied that juglone skeleton could be a primary template for the development of potent Mpro inhibitors.
- Cui, Jiahua,Jia, Jinping
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- ELECTROLYTE INCLUDING MIXTURE OF ACTIVE MATERIAL AND PRECURSOR THEREOF
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An electrolyte including a mixture of hydroxynaphtoquinone and a precursor material thereof is provided. The electrolyte may achieve higher capacities.
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Paragraph 0055-0059
(2021/10/02)
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- 2, 3-dihydronaphthalo [2, 3-b] furan-4, 9-diketone compound as well as preparation method and application thereof
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The invention provides a 2, 3-dihydronaphthalo [2, 3-b] furan-4, 9-diketone compound as well as a preparation method and application thereof, and belongs to the technical field of medicines. The invention particularly provides the 2, 3-dihydronaphthalo [2, 3-b] furan-4, 9-diketone compounds shown as general formulas I-A and I-B, a pharmaceutical composition containing the compounds, and a preparation method of the compounds. The compound has STAT3 inhibitory activity and can be used for preparing drugs for treating and/or preventing diseases related to STAT3 activity, and the diseases comprisevarious cancers such as breast cancer, lung cancer, oral cancer, kidney cancer, esophageal cancer, liver cancer, stomach cancer, intestinal cancer, cervical cancer and ovarian cancer.
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- Naphtho[2,3-: B] furan-4,9-dione synthesis via palladium-catalyzed reverse hydrogenolysis
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A reverse hydrogenolysis process has been developed for two-site coupling of 2-hydroxy-1,4-naphthoquinones with olefins to produce naphtha[2,3-b]furan-4,9-diones and hydrogen (H2). The reaction is catalyzed by commercially available Pd/C without oxidants and hydrogen acceptors, thereby providing an intrinsically waste-free approach for the synthesis of functionalized and potentially biologically relevant naphtha[2,3-b]furan-4,9-diones.
- Li, Jimei,Zhang, Jie,Li, Mingfei,Zhang, Chenyang,Yuan, Yongkun,Liu, Renhua
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supporting information
p. 2348 - 2351
(2019/02/27)
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- Small molecule compound having an IDO1/TDO double target, preparation method and applications thereof
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The invention belongs to the field of chemical medicine, and particularly relates to a small molecule compound having an IDO1/TDO double target, wherein the general formula is defined in the specification. According to the present invention, the embodiment schemes prove that the small molecule compound can simultaneously inhibit two enzymes IDO1 and TDO so as to reduce the immune evasion of tumorcells, achieve self-cure of tumor diseases, achieve good medicinal potential and provides new potential choice for clinical medication; the preparation method has characteristics of simpleness, mild reaction condition, convenient operation, convenient control, low energy consumption, high yield and low cost, and is suitable for industrial production; and the prepared compound has advantages of high biological activity, strong selectivity to tumor cells, remarkable drug-like properties, and good application prospects in the pharmaceutical industry.
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Paragraph 0048-0054
(2019/02/13)
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- Design, synthesis and activity of BBI608 derivatives targeting on stem cells
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STAT3 plays a vital role in maintaining the self-renewal of tumor stem cells. BBI608, a small molecule identified by its ability to inhibit gene transcription driven by STAT3 and cancer stemness properties, can inhibit stemness gene expression and kill stemness-high cancer cells isolated from a variety of cancer types. In order to improve the pharmacokinetic properties of BBI608 and the antitumor activity, a series of BBI608 derivatives were designed and synthesized here. Most of these compounds were more potent than BBI608 on HepG2 cells, compound LD-8 had the most potent inhibitory activity among them and was 5.4-fold more potent than BBI608 (IC50 = 11.2 μM), but had considerable activity on normal liver cells L-02. Compounds LD-17 (IC50 = 3.5 μM) and LD-19 (IC50 = 2.9 μM) were found to possess significant inhibitory activities and good selectivity. The results showed that compound LD-19 was worthy to investigate further as a lead compound according to its potent inhibitory activity, ideal ClogP value and better water solubility.
- Zhou, Qifan,Peng, Chen,Du, Fangyu,Zhou, Linbo,Shi, Yajie,Du, Yang,Liu, Dongdong,Sun, Wenjiao,Zhang, Meixia,Chen, Guoliang
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- BBI608 derivative as well as preparation and application thereof
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The invention belongs to the technical field of medicines, and relates to a BBI608 derivative and application of the BBI608 derivative in an anti-tumor medicine. The structures of the derivative and apharmacologically acceptable salt are as follows: as shown in the specification, wherein X, R1, R2 and R3 are as described in claims and the specification. The derivative and the pharmacologically acceptable salt can be used for preparing the anti-tumor medicine, particularly a medicine for treating the stomach cancer (including gastric esophageal cancer) and the pancreatic cancer. An HepG2 cellactivity research finds that the cell inhibition activities of most compounds are obviously higher than that of the anti-tumor medicine BBI608.(Refer to Specification).
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- METHOD OF PRODUCING 2-HYDROXY-1,4-NAPHTHOQUINONE
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Provided is a method of producing 2-hydroxy-1,4-naphthoquinone in a large amount, a high yield, and inexpensively. This method comprises oxidizing 2-hydroxynaphthalene with hydrogen peroxide in (1) an alkaline aqueous solution or in (2) a mixture of an alkaline aqueous solution with an inert organic solvent incompatible with water, in the presence of a vanadium catalyst.
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- Synthesis of pharmacologically important naphthoquinones and anticancer activity of 2-benzyllawsone through DNA topoisomerase-II inhibition
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Naphthoquinones are naturally occurring biologically active entities. Practical de novo syntheses of three naphthoquinones i.e. lawsone (1), lapachol (2), and β-lapachone (3b) have been achieved from commercially available starting materials. The conversion of lapachol (2) to β-lapachone (3b) was achieved through p-TSA/Iodine/BF3-etherate mediated regioselective cyclisation. Further, 2-alkyl and 2-benzyllawsone derivatives have been prepared as possible anticancer agents. Four derivatives exhibited significant anticancer activity and the best analogue i.e. compound 21a exhibited potential anticancer activity (IC50?=?5.2?μM) against FaDu cell line. Compound 21a induced apoptosis through activation of caspase pathway and exerted cell cycle arrest at S phase in FaDU cells. It also exhibited significant topoisomerase-II inhibition activity. Compound 21a was found to be safe in Swiss albino mice up to 1000?mg/kg oral dose.
- Kumar, Balagani Sathish,Ravi, Kusumoori,Verma, Amit Kumar,Fatima, Kaneez,Hasanain, Mohammad,Singh, Arjun,Sarkar, Jayanta,Luqman, Suaib,Chanda, Debabrata,Negi, Arvind S.
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p. 1364 - 1373
(2017/02/18)
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- Selective oxidation of 2-naphthol to 2-hydroxy-1,4-naphthoquinone with hydrogen peroxide catalyzed by 5,10,15,20-tetrakis(p-sulfonatophenyl)porphinatomanganese(III) chloride in aqueous solution.
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2-Naphthol has been selectively oxidized to 2-hydroxy-1,4-naphthoquinone (HNQ, Lawsone) with hydrogen peroxide in presence of 5,10,15,20-tetrakis-(p-sulfonatophenyl)porphinatomanganese (III) chloride as catalyst in alkaline aqueous solution. The catalytic oxidation afforded 2-hydroxy-1,4-naphthoquinone in high yield (95%). The effect of reaction parameters on the catalytic activity and the yield of HNQ have been investigated. UV–vis spectral analysis during oxidation reaction indicated that oxomanganese intermediate O = Mn(IV)TPPSCl was the active species in the oxidation reaction.
- Hassanein,El-Khalafy,Shendy
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p. 134 - 137
(2017/05/04)
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- Synthesis, applications and mechanistic investigations of C2 symmetric guanidinium salts
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A range of guanidinium catalysts was prepared in six or seven synthetic steps and applied to the phase transfer alkylation of a glycinate Schiff's base in 21-86% ee as well as the phase transfer epoxidation of some chalcones in 85-94% ee. Using a spectrophotometric method, pKa values in the range 13.2-13.9 in DMSO have been determined for some of the catalysts highlighting an increase in basicity relative to achiral tetramethylguanidine (pKa=13.0) and a mechanism involving the protonated guanidinium ion as a phase transfer catalyst is proposed. The use of two of the catalysts for the addition of nucleophiles in Michael addition reactions was investigated and both were found to be effective catalysts. A counterion effect was apparent in these reactions, but no enantioselectivity was observed.
- Allingham, Matthew T.,Bennett, Elliot L.,Davies, Deniol H.,Harper, Philip M.,Howard-Jones, Andrew,Mehdar, Yassin T.H.,Murphy, Patrick J.,Thomas, Dafydd A.,Caulkett, Peter W.R.,Potter, David,Lam, Casey M.,O'Donoghue, Annmarie C.
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supporting information
p. 496 - 503
(2015/12/31)
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- Ru-Catalyzed Asymmetric Hydrogenative/Transfer Hydrogenative Desymmetrization of Meso-Epoxy Diketones
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Via a strategy of asymmetric reductive desymmetrization, chiral cis-epoxy naphthoquinols with multiple contiguous stereocenters and functional groups were synthesized with excellent enantioselectivities (96-99% ee) and diastereoselectivities (8/1-15/1). A combined asymmetric hydrogenation/transfer hydrogenation mechanism was proposed based on experimental results.
- Hong, Yuping,Chen, Jianzhong,Zhang, Zhenfeng,Liu, Yangang,Zhang, Wanbin
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p. 2640 - 2643
(2016/06/15)
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- NbCl5 mediated biomimetic cascade reaction: Efficient and scalable one-pot synthesis of dunnione and nor-β-lapachone
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A regioselective biomimetic synthesis of bioactive natural products dunnione and nor-β-lapachone is described. This cascade provides a new strategy of a one-pot process mediated by Lewis acid NbCl5 involving a tandem Claisen rearrangement-cyclization reaction. This procedure was efficient, mild, and easily scalable that avoided using highly hazardous concd H2SO4.
- Bian, Jinlei,Qian, Xue,Fan, Jun,Li, Xiang,Sun, Haopeng,You, Qidong,Zhang, Xiaojin
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p. 397 - 400
(2015/04/27)
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- Activated zeolites and heteropolyacids: An efficient catalysts for the synthesis of triacetoxyaromatic precursors of hydroxyquinones
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The Thiele-Winter reaction is of interest for synthesis of triacetoxyaromatic precursors of hydroquinones. Liquid acid such as, chlorosulfonic acid and solid acids like heteropolyacids have an efficient catalyst can effectively replace sulfuric acid in acetoxylation reaction of quinones without use of organic solvent at room temperature.
- Hadjila, Dokari,Mohamed, Hammadi
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p. 6112 - 6116
(2013/07/26)
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- 3-dimensional photonic crystal light emitting element
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In a light emitting device, efficiency and stability are improved. A light emitting device 10 includes a three-dimensional photonic crystal 20. The three-dimensional photonic crystal includes a first defect part 70 forming a resonator including an active medium, a second defect part 80 forming a waveguide for taking out light generated by the resonator, a P clad part 40 formed of a P-type semiconductor, and a N clad part 50 formed of a first N-type semiconductor. The second defect part is provided only in the N clad part among the P clad part and the N clad part. At least a part of the second defect part is formed of a second N-type semiconductor and constitutes a heat radiation unit which radiates a heat to the outside.
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- Design, synthesis, and biological testing of novel naphthoquinones as substrate-based inhibitors of the quinol/fumarate reductase from Wolinella succinogenes
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Novel naphthoquinones were designed, synthesized, and tested as substrate-based inhibitors against the membrane-embedded protein quinol/fumarate reductase (QFR) from Wolinella succinogenes, a target closely related to QFRs from the human pathogens Helicobacter pylori and Campylobacter jejuni. For a better understanding of the hitherto structurally unexplored substrate binding pocket, a structure-activity relationship (SAR) study was carried out. Analogues of lawsone (2-hydroxy-1,4-naphthoquinone 3a) were synthesized that vary in length and size of the alkyl side chains (3b-k). A combined study on the prototropic tautomerism of 2-hydroxy-1,4-naphthoquinones series indicated that the 1,4-tautomer is the more stable and biologically relevant isomer and that the presence of the hydroxyl group is crucial for inhibition. Furthermore, 2-bromine-1,4-naphthoquinone (4a-c) and 2-methoxy-1,4-naphthoquinone (5a-b) series were also discovered as novel and potent inhibitors. Compounds 4a and 4b showed IC50 values in low micromolar range in the primary assay and no activity in the counter DT-diaphorase assay.
- Nasiri, Hamid Reza,Madej, M. Gregor,Panisch, Robin,Lafontaine, Michael,Bats, Jan W.,Lancaster, C. Roy D.,Schwalbe, Harald
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p. 9530 - 9541
(2014/01/06)
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- An environmentally friendly electrochemical method for synthesis of benzofuranoquinone derivatives
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Electrochemical oxidation of catechols (1a-c) has been studied in the presence of 2-hydroxy-1,4-naphtoquinone (3b) in aqueous solutions, using cyclic voltammetry and controlled-potential coulometry. The results indicated that the electrochemically generated o-benzoquinones (2a-c) participate in Michael addition reaction with 3b to the corresponding benzofuranoquinones (8a-c, 10a-c). The electrochemical synthesis of these compounds has been successfully preformed at a carbon rod electrode with good yields using an environmentally friendly method.
- Hosseiny Davarani, Saied Saeed,Shamsipur, Mojtaba,Nematollahi, Davood,Ramyar, Somayyeh,Masoumi, Leila
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p. 1198 - 1202
(2008/09/16)
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- An efficient C-C bond cleavage of 1,2-diols using tetraethylammonium superoxide
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Tetraethylammonium superoxide, generated in situ by the phase-transfer reaction of potassium superoxide and tetraethylammonium bromide in DMF, brings about an easy cleavage of vicinal diols and related dihydroxy arenes under mild reaction conditions, at room temperature.
- Singh, Krishna Nand,Kumar, Rajesh,Shukla, Ajay Kumar
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p. 1347 - 1351
(2008/09/18)
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- Regiocontrolled synthesis and HIV inhibitory activity of unsymmetrical binaphthoquinone and trimeric naphthoquinone derivatives of conocurvone
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Unsymmetrical biquinone and trimeric quinone derivatives were synthesized using halotriflate-biselectrophilic naphthoquinones through stepwise regioselective quinone substitution chemistry and evaluated for their ability to inhibit the cytopathogenic effects of HIV-1 using an MTT colorimetric assay. Compounds were also screened for their ability to inhibit the activity of HIV-1 integrase in vitro. Pyranylated trimeric quinones and biquinones exhibited both antiviral activity and integrase inhibitory activity. Conocurvone 1 and trimeric quinone 21 were the most potent HIV integrase inhibitors in the series. All of the biquinones showed HIV inhibitory activity. Simple methoxy substituted biquinones did not inhibit HIV-1 integrase.
- Stagliano, Kenneth W.,Emadi, Ashkan,Lu, Zhenhai,Malinakova, Helena C.,Twenter, Barry,Yu, Min,Holland, Louis E.,Rom, Amanda M.,Harwood, John S.,Amin, Ronak,Johnson, Allison A.,Pommier, Yves
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p. 5651 - 5665
(2007/10/03)
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- A survey on the reactivity of phenyliodonium ylide of 2-hydroxy-1,4- naphthoquinone with amino compounds
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The phenyliodonium ylide of 2-hydroxy-1,4-naphthoquinone reacts with aminoesters, ureas, aminoalcohols and aminophenols in refluxing dichloromethane to afford good yields of indanedione 2-carboxamido compounds, that in solution exist in an enol-amide form. The same reactants in a copper-catalyzed reaction afford mainly the corresponding N-arylo compounds. Arylhydrazines are mainly oxidized by the ylide and arylation occurs only in a low yield.
- Spagou, Konstantina,Malamidou-Xenikaki, Elizabeth,Spyroudis, Spyros
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p. 226 - 237
(2007/10/03)
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- Studies on the reactivity of aryliodonium ylides of 2-hydroxy-1,4-naphthoquinone: Reactions with amines
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Aryliodonium ylides of 2-hydroxy-1,4-naphthoquinone react with amines in refluxing dichloromethane to afford good yields of indanedione 2-carboxamides 5, through a ring-contraction and α,α′-dioxoketene formation reaction. These amides exist in solution in an unusual enol-amide form. In contrast, the same reactants in a copper-catalyzed reaction afford arylamines and 3-iodo-4-hydroxy-1,2-naphthoquinone.
- Malamidou-Xenikaki, Elizabeth,Spyroudis, Spyros,Tsanakopoulou, Maria
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p. 5627 - 5631
(2007/10/03)
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- Effects of hydroxypropyl-β-cyclodextrin on the chemical stability of a naphthoquinone in aqueous solutions
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2-Hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine (1), an antibacterial agent, was shown to form inclusion complexes with HP-β-CD in aqueous solution. In the present work the kinetics of 1 degradation in aqueous buffer solution was investigated as a function of pH (2.34-3.95), HP-β-CD concentration (0%-28% (w/v)) and temperature (60-90 °C). A second-order derivative spectroscopic methodology was developed for the kinetic investigations. The degradation showed to follow pseudo-first-order kinetics. Also, an specific acid catalysis was found and the introduction of up to 28% (w/v) HP-β-CD to the reaction medium did not change this kinetic behaviour. The obtained results indicated that HP-β-CD stabilises 1 against degradation in aqueous solutions.
- Linares,Longhi
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- Supported metalated phthalocyanine as catalyst for oxidation by molecular oxygen. Synthesis of quinones and carbonyl compounds
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Supported metalated phthalocyanine on K1O or on lamellar zirconium phosphate catalyses the oxidation of hydroquinones (and phenols) into quinones. Some interesting natural napthoquinones were also prepared (Juglone, Menadione, Lawsone, Phthiocol). Supported metalated phthalocyanine was also used in re-oxidation by oxygen of palladium and ruthenium, in the Wacker oxidation of olefins into ketones, in the oxidation of cyclohexadiene and in oxidation of benzylic alcohols in aldehydes.
- Villemin, Didier,Hammadi, Mohamed,Hachemi, Messaoud
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p. 1501 - 1515
(2007/10/03)
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- Pathway of anthracene modification under simulated solar radiation
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Exposure of polycyclic aromatic hydrocarbons (PAHs) to sunlight results in rapid structural photomodification generally via oxidation reactions. These PAH modification products are in many cases more toxic than their parent compounds. In this study, anthracene (ANT), a rapidly photooxidized PAH, was irradiated with simulated solar radiation (SSR, 100 μmol m-2 s- 1) in aqueous solution to examine the photomodification pathway. The photoproducts formed were identified by HPLC. The ANT product profile after 9 h in SSR was very complex, with more than 20 compounds detected. The photoproducts formed were anthraquinones, benzoic acids, benzaldehydes and phenols showing the process to be oxidative in nature. Some of the anthraquinones were themselves subject to photooxidation, and were thus intermediates in the product pathway. The kinetics of ANT photooxidation revealed a pseudo first-order reaction with a half-life of 2 h under the SSR source used. The kinetics of product formation allowed deduction of a probable photomodification pathway. This study indicates that PAH photooxidation products are likely to exist as complex, dynamically changing mixtures in PAH contaminated aquatic environments.
- Mallakin, Ali,George Dixon,Greenberg, Bruce M.
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p. 1435 - 1441
(2007/10/03)
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- Selenium(IV) oxide catalyzed oxidation of aldehydes to carboxylic acids with hydrogen peroxide
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A convenient method for oxidative transformation of aromatic, heteroaromatic and aliphatic aldehydes into carboxylic acids is presented. It is based on the oxidation of aldehydes in THF using 30% hydrogen peroxide in the presence of 5 molar % of selenium(IV) oxide. The scope and limitation of the method are discussed.
- Brzaszcz,Kloc,Maposah,Mlochowski
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p. 4425 - 4434
(2007/10/03)
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- Formation of 2-hydroxy-1,4-naphthoquinone by the degradation of Eriochrome Blue Black R in aqueous solution
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The o,o′-dihydroxyazo dyes of the Eriochrome type have a reduced stability in aqueous alkaline solutions under aerobic conditions, as compared with other arylazo compounds. The major degradation product of Eriochrome Blue Black R (I) is 2-hydroxy-1,4-naphthoquinone (IX), which very likely results as the outcome of subsequent reactions. Compound IX has been identified by comparison with an authentic sample by means of IR- and UV-spectra, as well as by TLC and HPLC. 2-Hydroxy-1,4-naphthoquinone was also identified among the decomposition products of Eriochrome Black A (II) and Eriochrome Black T (III). It is supposed that one of the degradation pathways of these dyes begins with the breakdown of the C-N bond between the azo group and the coupling component, and is followed by subsequent oxidative steps. Suggestions concerning the reaction mechanism are given.
- Salló, Aurora,Schmidt, Walter,?iclovan, Dorina
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p. 297 - 300
(2007/10/03)
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- Reactions of N-sulfinylarylamines with 1,4-benzoquinone and 1,4-naphthoquinone: synthesis of N-aryl sulfinamoyl quinones and their hydrolysis to hydroxyquinones
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N-Sulfinylarylamines react with 1,4-naphthoquinone to give 2-(N-arylsulfinamoyl)-1,4-naphthoquinones.The reaction is believed to occure via an initial 2 + 2 cycloaddition of the N=S bond of the N-sulfinylamine with 1,4-naphthoquinone, followed by fragmentation of the 1,2-thiazetidine 1-oxide intermediate with a 1,3-H shift.N-Sulfinylarylamines add regiospecifically to 5-hydroxy-1,4-naphthoquinone to give 3-(N-arylsulfinamoyl)-5-hydroxy-1,4-naphthoquinones. 1,4-Benzoquinone reacts with three molecules of N-sulfinylarylamine to give adducts.Two molecules of N-sulfinylarylamine react with 1,4-benzoquinone as in the case of 1,4-naphthoquinone and the third molecule reacts at one of the C=O groups of the benzoquinone with the elimination of a molecule of SO2.Hydrolysis of 2-(N-arylsulfinamoyl)-1,4-naphthoquinones with aqueous HCl gives 2-hydroxy-1,4-naphthoquinone.
- Amarasekara, Ananda S.,Pathmasiri, W. Wimal
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p. 1653 - 1658
(2007/10/02)
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- Isoxazoles. 8. Preformulation studies of an isoxazolylnaphthoquinone derivative
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The degradation kinetics of 2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4- naphthoquinone 4-imine (1) in a 25% solution of ethyl alcohol in water has been studied. The rate constants were observed to follow pseudo-first-order kinetics in all cases. The pH-rate profile indicated a negligible decomposition at pH values higher than its pK(a2) value [5.40 ± 0.14 (*n = 6)]. Un-ionized 1 was subject to specific acid catalysis. The ionic strength did not affect the stability of the drug. These data can be used to develop a stable oral liquid dosage form of the drug.
- Longhi,De Bertorello,Granero
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p. 336 - 338
(2007/10/02)
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- Method for dyeing keratinous fibres using a monohydroxyindole or dihydroxyindole and a non-oxidizing aromatic carbonyl derivative and dyeing agent
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The present invention relates to a method for dyeing keratinous fibers, characterized in that the following are applied to the fibers: a) a composition (A) containing, in a medium appropriate for dyeing, at least one monohydroxyindole or dihydroxyindole, this application being preceded or followed by the application of b) a composition (B) containing, in a medium appropriate for dyeing, at least one aromatic carbonyl derivative chosen from hydroxyacetophenones, hydroxybenzophenones, 2-hydroxy-1,4-benzoquinones, hydroxy-1,4-naphthoquinones,amino-1,4-naphthoquinones,hydroxy-9,10-anthraquinones and amino-9,10-anthraquinones. It also relates to the dyeing agents for carrying it out.
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- Synthetic approaches to 3-amino-1,4-naphthoquinone-2-carboxylic acid derivatives and photochemical synthesis of novel 1,4,5,10-tetrahydro-5,10- dioxo-2H-naphth[2,3-d][1,3]oxazine derivatives
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Synthesis of 3-alkylamino-1,4-naphthoquinone-2-carboxylic acid (2) was attempted. Although 3-(1-piperidinyl)-1,4-naphthoquinone-2-carboxylic acid (2a) was not obtained, probably because of its instability, the esters (18a, b) of 2a could be prepared. 2-Alkylamino-3-hydroxymethyl-1,4-naphthoquinones (9a-g) were photochemically cyclized to the 1,4,5,10-tetrahydro-5,10-2H- napth[2,3-d][1,3]oxazines (19a-g), containing a novel heterocyclic ring system in moderate yields. Anti-bacterial activity of the prepared compounds was weak or insignificant.
- Ohta,Hinata,Yamashita,Kawasaki,Shoji,Yoshikawa,Obana
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p. 1185 - 1190
(2007/10/02)
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- Friedel-Crafts Coordinated Processes: Highly Selective Synthesis of Hydroxynaphthoquinones
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Simple preparation of ethyl 3-hydroxy-1,4-naphthoquinone-2-carboxylates 2 including heterocyclic analogs is accomplished by C-regioselective bis-acylation of aromatic and heteroaromatic β-keto esters 1.Compounds 2 are readily hydrolyzed and decarboxylated to the corresponding 2-hydroxy-1,4-naphthoquinone derivatives 3.
- Sartori, Giovanni,Bigi, Franca,Canali, Giacomo,Maggi, Raimondo,Casnati, Giuseppe,Tao, Xiaochun
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p. 840 - 843
(2007/10/02)
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- Reactivity of potassium superoxide in heterogeneous phase: Oxidation of naphthalenediols and hydroxylated naphthoquinones
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Oxidation of dihydroxynaphthalenes by potassium superoxide (KO2) in heterogeneous aprotic media yields mono- or dihydroxynaphthoquinones, depending on the relative position of the hydroxy groups on the naphthalene moiety. The reaction proceeds mainly at the solid-liquid interface and naphthoquinones can be obtained with good yields.
- De Min,Croux,Tournaire,Hocquaux,Jacquet,Oliveros,Maurette
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p. 1869 - 1882
(2007/10/02)
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- Naphthalene anti-psoriatic agents
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Psoriasis in mammals is relieved by topically administering naphthalenes of the formula: STR1 wherein: R1 is alkoxy, alkylthio, optionally substituted phenoxy or optionally substituted phenylthio; R2 is hydrogen, lower alkyl, optionally substituted phenyl or optionally substituted phenylalkyl; R3 is lower alkyl, lower alkoxy, or halo and m is 0, 1 or 2, or R3 is optionally substituted phenyl, optionally substituted phenyl lower alkyl, optionally substituted phenyl lower alkoxy, amino, lower alkylamino, lower dialkylamino, cyano, or S(0)n R wherein R is lower alkyl; optionally substituted phenyl; optionally substituted phenyl lower alkyl; or optionally substituted heterocyclic aryl of three to nine ring atoms containing one or two heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur, and the pharmaceutically acceptable acid addition salts thereof; and m is 1 and n is 0, 1 or 2; and W is alkyl of one to seven carbon atoms, optionally substituted phenyl or optionally substituted benzyl.
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- Isoxazoles. VII: Hydrolysis of 4-methyl-5-isoxazolylnaphthoquinone derivatives in aqueous solutions
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The kinetics for the degradation of 2-(4-methyl-5-isoxazolylamine)-N-(4-methyl-5-isoxazolyl)-1,4- naphthoquinone-4-imine (1) in solution were investigated at 70 °C and at a constant ionic strength of 0.5 over a pH range of 1.75 to 12.85. The degradation rates were determined by absorption and second-derivative UV spectrometry. Two degradation products were identified in acidic and neutral pHs; they are 4-N-(4-methyl-5-isoxazolyl)-1,2-naphthoquinone (2) and 2-methyl-cyanoacetamide (5), respectively. In alkaline pH, two degradation products, 2-hydroxy-N-(4-methyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine (3) and 5-amino-4-methylisoxazole (4), were isolated. The pathway for degradation of 1 in acidic and neutral pH followed consecutive first-order kinetics since 2 undergoes hydrolysis giving 2-hydroxy-1,4-naphthoquinone (6) and 2-methylcyanoacetamide (5). No appreciable buffer effect on the degradation of 1 and 2 was observed for any of the buffer species in this study. The pH-rate profiles exhibited specific acid and specific basic catalysis for 1 and specific acid catalysis for 2. The maximum stability for 1 and 2 occurred in the neutral pH region.
- Longhi,De Bertorello,Brinon
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p. 573 - 577
(2007/10/02)
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- Isoxazoles VI: Aspects of the chemical stability of a new naphthoquinone-amine in acidic aqueous solution
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Some aspects of the chemical degradation of N-(3,4-dimethyl-5-isoxazolyl)-4-amino-1,2-naphthoquinone were investigated as a function of pH and temperature. In acid and neutral pH, four main degradation products were identified: 2-hydroxy-1,4-naphthoquinone, 2-butanone, ammonia, and hydroxylamine. No significant buffer effects were observed for the buffer species used in this study. The pH-rate profile exhibited a specific acid catalysis which is important at pH values 3.5, and an inflection point at pH 1.10 corresponding to a pK(a) value. From Arrhenius plots, the activation energy was found to be 17.8 ± 0.3 kcal/mol.
- Longhi,De Bertorello
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p. 754 - 757
(2007/10/02)
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- Quinones. Part 11. The Reaction of o-Aminothiophenol with o-Benzo- and o-Naphtho-quinones: A New Route to 1H-Phenothiazin-1-ones
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1H-Phenothiazin-1-ones can be obtained by the condensation of o-aminothiophenol with 3,5-di-t-butyl- and 3-t-butyl-5-phenyl-o-benzoquinones.In the absence of large blocking groups the phenothiazinones are unstable.A methyl group at C-4 leads via the quinone-methide tautomer, to formation of a spiro-dimer the crystal structure of which was determined by X-ray analysis.By further reaction with o-aminothiophenol, 1H-phenothiazin-1-ones yield triphenodithiazines (benzothiazinophenothiazines). o-Naphthoquinones do not form benzo-1H-phenothiazin-1-ones with o-aminothiophenol.The parent compound yields 4-hydroxy-3H-benzophenothiazin-3-one by initial thiol addition at C-4 followed by rearrangement.
- Mackenzie, Neil E.,Surendrakumar, Sivagnanasundram,Thomson, Ronald H.,Cowe, Heather J.,Cox, Philip J.
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p. 2233 - 2242
(2007/10/02)
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- Dimeric Naphthoquinones, XVIII. - Ammonium Cerium(IV) Nitrate as Oxidising Agent: peri-Hydroxylation of Juglones giving Naphthazarins
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5,8-Dialkoxy-1-naphthols (type 6a) which are easily accessible starting from juglones (5a) are oxidised under mild conditions using ammonium cerium(IV) nitrate, yielding with high p-selectivity the corresponding 1,4-naphthoquinones (7a).By dealkylation of the latter, substituted 1,8-dihydroxy-1,4-naphthoquinones (1a) are obtained in good yields.
- Laatsch, Hartmut
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p. 1655 - 1668
(2007/10/02)
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- Stepwise Oxidation of 1,2-Naphthoquinone and Cycloheptanaphthalene-7,8-dione (o-Pleiadienequinone)
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Oxidation of cycloheptanaphthalene-7,8-dione (o-pleiadienequinone) (1) and o-naphthoquinone (2) yields the corresponding epoxides 14 and 3, respectively.The stepwise oxidation of 3 yields derivatives of 1,2,3,4-tetraoxonaphthalene, while the stepwise oxidation of 14 finally results in the formation of phenalenetrione or phenalenone derivatives.
- Gleiter, Rolf,Dobler, Walter
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p. 4725 - 4742
(2007/10/02)
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- UEBER DIE REAKTION VON α- UND β-TETRALON MIT KALIUMSUPEROXID
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The reaction of α- and β-tetralone with potassium superoxide is described.In addition to 2-hydroxy-1,4-naphthoquinone α-naphthol is formed from α-tetralone and β-naphthol and 2-carboxy-benzenepropionic acid from β-tetralone.
- Lissel, Manfred
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p. 2213 - 2214
(2007/10/02)
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- OXYDATION DES TETRALONES PAR LE SUPEROXYDE DE POTASSIUM SOLUBILISE PAR ETHER-COURONNE
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α and β-tetralones are oxidised in tetrahydrofuran solution by means of potassium superoxide with crown-ether to give 2-hydroxy-1,4 naphtoquinone with fair to good yields.
- Hocquaux, Michel,Jacquet, Bernard,Vidril-Robert, Daniele,Maurette, Marie-Therese,Oliveros, Esther
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p. 533 - 536
(2007/10/02)
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