526-86-3Relevant academic research and scientific papers
Steric effects of substituents of quinones on the oxygenation of ethylbenzene catalyzed by NHPI/quinone and the catalytic oxidation of ascorbate
Yang, Xiaomei,Wang, Ying,Zhang, Chaofeng,Fang, Tao,Zhou, Lipeng,Zhang, Wei,Xu, Jie
, p. 693 - 697 (2011)
The substituents of quinones play an important role in modulating the kinetics of the electron- and proton-transfer reaction. In this paper, the steric effects of substituents of quinones on their catalytic performance were studied in the oxidation of ethylbenzene and ascorbate. The substituents limited the addition of the free radicals to the C=C double bonds of the quinone ring because of the steric hindrance. On the other hand, too many substituents hindered the contact between the active site (C=O) of quinone and the reactant. So, the quinones with two substituents presented better catalytic performance than those with more or less substituents. These results will be helpful in designing the quinone compounds for drugs and in understanding the catalytic behavior of quinones in biochemistry.
Development of new and efficient polymer-supported hypervalent iodine reagents
Ficht, Simon,Mülbaier, Marcel,Giannis, Athanassios
, p. 4863 - 4866 (2001)
The aminomethylpolystyrene-supported (diacetoxyiodo)benzene reagents 4a and 4b were prepared for the first time. Using these reagents several hydroquinones and phenols can be oxidized to the corresponding quinones. Spirocyclization of phenylacetic acid and of N-protected tyrosine derivatives could also be accomplished.
Correlation between carbon-carbon bond length and the ease of retro Diels-Alder reaction
Kotha, Sambasivarao,Banerjee, Shaibal,Shaikh, Mobin
, p. 1369 - 1371 (2014)
The bond length between C8-C9 in (1′ R,4′ S,4a′ R,8a′ S)-6′,7′-dimethyl-1′,4′,4a′,8a′-tetrahydrospiro [cyclopropane-1,9′-[1,4]methanonaphthalene]-5′,8′-dione is 1.571 (2) ? and between C7-C12 is 1.567 (2) ? which are longer than the corresponding bond length for saturated bicyclic systems (1.531-1.535 ?). This paper reports the correlation between bond length and the ease of retro Diels -Alder reaction.
Design, synthesis, and rearrangement studies of gem-dimethyl containing cage systems
Kotha, Sambasivarao,Cheekatla, Subba Rao
, (2020)
A variety of functionalized cage compounds and D3-trishomocubane derivatives have been assembled via the Diels–Alder strategy, with reductive cleavage of the cyclopropane ring and metal promoted ring rearrangement as key steps. We have installed the gem-dimethyl moiety on the norbornane ring system containing a cage framework by a late-stage synthetic manipulation involving the hydrogenolysis of the cyclopropane ring with the aid of Adams’ catalyst (PtO2). Several cage molecules containing methyl substituents were synthesized by starting with inexpensive and commercially available materials such as 2,3-dimethylhydroquinone, Zn/AcOH, and endo-dicyclopentadiene. These cage pentacycloundecane frameworks assembled here are difficult to synthesize by conventional routes. Some of these gem-dimethyl cage systems and D3-trishomocubane derivative was firmly supported on the basis of single-crystal X-ray diffraction studies.
A relationship between amide hydrogen bond strength and quinone reduction potential: Implications for photosystem I and bacterial reaction center quinone function
Feldman, Ken S.,Hester II, D. Keith,Golbeck, John H.
, p. 4891 - 4894 (2007)
A series of 11 simple phylloquinone derivatives, each lacking the extended phytyl side chain but featuring H-bond donor amides at one or both peri positions, were prepared and some salient physical properties were measured. A correlation between both IR frequency and NMR peak position, as indicators of internal H-bond strength, and the quinone half-wave reduction potential, was observed. These data are consistent with the prevailing hypothesis that quinone carbonyl H-bonding in general, and stronger H-bonds in particular, favorably bias the endogenous quinone's electrochemical potential toward easier reduction.
Neuroprotection in the MPTP parkinsonian C57BL/6 mouse model by a compound isolated from tobacco
Castagnoli, Kay P.,Steyn, Stefanus J.,Petzer, Jacobus P.,Van Der Schyf, Cornelis J.,Castagnoli Jr., Neal
, p. 523 - 527 (2001)
Epidemiological evidence suggests a lower incidence of Parkinson's disease in smokers than in nonsmokers. This evidence, together with the lower levels of brain monoamine oxidase (MAO) activity in smokers and the potential neuroprotective properties of MAO inhibitors, prompted studies which led to the isolation and characterization of 2,3,6-trimethyl-1,4-naphthoquinone (TMN), an MAO-A and MAO-B inhibitor which is present in tobacco and tobacco smoke. Results of experiments reported here provide evidence that this compound protects against the MPTP-mediated depletion of neostriatal dopamine levels in the C57BL/6 mouse. These results support the hypothesis that the inhibition of MAO by constituents of tobacco smoke may be related to the decreased incidence of Parkinson's disease in smokers.
Structural Study of the Methylnaphthazarins. X-Ray Structure of the Tetramethylnaphthazarin, a Charge Transfer Complex
Rodriguez, Jose-Gonzalo,Pablo, Alfonso De,Smith-Verdier, Pilar
, p. 3957 - 3962 (1986)
The synthesis and analysis by 1H NMR of the methyl substituted naphthazarins were attempted.The chemical shifts of the substituents and of the ring protons were compared with those in their diacetates and were then correlated with the quinonoid or benzenoid nature of the rings.X-Ray diffraction analysis of tetramethylnaphthazarin, 2,3,6,7-tetramethyl-5,8-dihydroxy-1,4-naphthoquinone, has shown that this exists, in solid state, as a centrosymmetric charge-transfer complex with itself.The compound crystallizes in the Ibam space group, with an orthorombic cell of dimensions a=17.479(1), b=9.983(1), c=6.752(1) Angstroem, and four molecules in the unit cell.The crystal is built from molecules stacked up the c-axis and the interplanar distance between two overlapping molecules is 3.38 Angstroem.
Aerobic Oxidation of Dihydroxyarenes Substrates Catalyzed by Polymer-Supported RuII-Pheox/Silica-Gel: A Beneficial Route for Purification of Industrial Water
Abu-Elfotoh, Abdel-Moneim
supporting information, p. 236 - 243 (2022/04/09)
A broad class of dihydroxyarenes were easily oxidized by aerobic oxygen to quinone products in excellent yields under the catalytic effect of polymer-supported RuII-Pheox/silica-gel catalyst. By using this combined catalyst, hydroquinone and catechol derivatives with electron-donating groups were easily oxidized by molecular oxygen to quinone products in 90% to >99% yield, while in the case of electron-withdrawing group, only 70% was obtained. The biologically useful 1,4-Naphthoqinone products were obtained in 83% to 90%. The catalyst was easily obtained and reused many times without a significant decrease in reactivity. Interestingly, a sample of industrial water contaminated with phenolic compounds was subjected to aerobic oxidation by using this catalyst, and the resultant quinones were detected within one day and the catalyst was removed and reused several times with different contami-nating samples with the same efficiency. Other catalytic oxidations by using this promising catalyst were investigated.
Pseudocyclic bis-N-heterocycle-stabilized iodanes - synthesis, characterization and applications
Boelke, Andreas,Lork, Enno,Nachtsheim, Boris J.,Sadat, Soleicha
supporting information, p. 7434 - 7437 (2021/08/03)
Bis-N-heterocycle-stabilized λ3-iodanes (BNHIs) based on azoles are introduced as novel structural motifs in hypervalent iodine chemistry. A performance test in a variety of benchmark reactions including sulfoxidations and phenol dearomatizations revealed a bis-N-bound pyrazole substituted BNHI as the most reactive derivative. Its solid-state structure was characterizedviaX-ray analysis implying strong intramolecular interactions between the pyrazole nitrogen atoms and the hypervalent iodine centre.
Plastoquinone analogs: a potential antimicrobial lead structure intensely suppressing Staphylococcus epidermidis and Candida albicans growth
Ataman, Merve,Ozbek-Celik, Berna,Bayrak, Nilüfer,Matarac?-Kara, Emel,Tuyun, Ama? Fatih,Y?ld?r?m, Hatice,Y?ld?z, Mahmut
, p. 1728 - 1737 (2021/08/06)
The aim of this study was to evaluate the antimicrobial activity of twenty-five Plastoquinone analogs synthesized previously in a panel of seven bacterial strains (three Gram-positive and four Gram-negative bacteria) and three fungi. PQ1, which does not contain any substituent(s) on the phenyl ring, was the most potent compound against Staphylococcus epidermidis (8-fold more potent than Cefuroxime, MIC = 1.22 μg/mL). The antifungal profile of all Plastoquinone analogs indicated that three analogs (PQ1, PQ2, and PQ7) displayed the best antifungal activity against Candida albicans, which was about the same activity with the reference standard (MIC = 4.88 μg/mL). The structure-activity relationship study was also carried out to reveal important chemical features. After probing twenty-five Plastoquinone analogs for a potential antimicrobial lead structure, two analogs (PQ1 and PQ25) were selected for further investigation for biofilm evaluation. Based on the tests performed, there was a significant positive correlation between inhibition of the biofilm attachment and time. The results showed that both analogs (PQ1 and PQ25) are able to reduce biofilm mass. Finally, these findings endorse us further efforts to optimize two phenotypes of the Plastoquinone analogs (PQ1 and PQ25) to develop potential antimicrobial drug candidates. [Figure not available: see fulltext.]
