6050-13-1Relevant articles and documents
Electronic, Magnetic, and Redox Properties and O2 Reactivity of Iron(II) and Nickel(II) o-Semiquinonate Complexes of a Tris(thioether) Ligand: Uncovering the Intradiol Cleaving Reactivity of an Iron(II) o-Semiquinonate Complex
Wang, Peng,Killian, Michelle M.,Saber, Mohamed R.,Qiu, Tian,Yap, Glenn P. A.,Popescu, Codrina V.,Rosenthal, Joel,Dunbar, Kim R.,Brunold, Thomas C.,Riordan, Charles G.
, p. 10481 - 10495 (2017)
The iron(II) semiquinonate character within the iron(III) catecholate species has been proposed by numerous studies to account for the O2 reactivity of intradiol catechol dioxygenases, but a well-characterized iron(II) semiquinonate species that exhibits intradiol cleaving reactivity has not yet been reported. In this study, a detailed electronic structure description of the first iron(II) o-semiquinonate complex, [PhTttBu]Fe(phenSQ) [PhTttBu = phenyltris(tert-butylthiomethyl)borate; phenSQ = 9,10-phenanthrenesemiquinonate; Wang et al. Chem. Commun. 2014, 50, 5871-5873], was generated through a combination of electronic and M?ssbauer spectroscopies, SQUID magnetometry, and density functional theory (DFT) calculations. [PhTttBu]Fe(phenSQ) reacts with O2 to generate an intradiol cleavage product, diphenic anhydride, in 16% yield. To assess the dependence of the intradiol reactivity on the identity of the metal ion, the nickel analogue, [PhTttBu]Ni(phenSQ), and its derivative, [PhTttBu]Ni(3,5-DBSQ) (3,5-DBSQ = 3,5-di-tert-butyl-1,2-semiquinonate), were prepared and characterized by X-ray crystallography, mass spectrometry, 1H NMR and electronic spectroscopies, and SQUID magnetometry. DFT calculations, evaluated on the basis of the experimental data, support the electronic structure descriptions of [PhTttBu]Ni(phenSQ) and [PhTttBu]Ni(3,5-DBSQ) as high-spin nickel(II) complexes with antiferromagnetically coupled semiquinonate ligands. Unlike its iron counterpart, [PhTttBu]Ni(phenSQ) decomposes slowly in an O2 atmosphere to generate 14% phenanthrenequinone with a negligible amount of diphenic anhydride. [PhTttBu]Ni(3,5-DBSQ) does not react with O2. This dramatic effect of the metal-ion identity supports the hypothesis that a metal(III) alkylperoxo species serves as an intermediate in the intradiol cleaving reactions. The redox properties of all three complexes were probed using cyclic voltammetry and differential pulse voltammetry, which indicate an inner-sphere electron-transfer mechanism for the formation of phenanthrenequinone. The lack of O2 reactivity of [PhTttBu]Ni(3,5-DBSQ) can be rationalized by the high redox potential of the metal-ligated 3,5-DBSQ/3,5-DBQ couple.
Synthesis and Evaluation of Antibacterial Activity of 1,2,4-Oxadiazole-Containing Biphenylcarboxylic Acids
Baikov, S. V.,Presnukhina, S. I.,Shetnev, A. A.,Tarasenko, M. V.
, p. 1611 - 1619 (2020/10/15)
Abstract: A one-pot method for the synthesis of biphenylcarboxylic acids containing 1,2,4-oxadiazole ring in the NaOH–DMSO system was developed. The results of in vitro experiments showed that the synthesized compounds exhibit antibacterial activity against susceptible strains of E. coli and S. aureus.
Mechanistic Insights into Selective Oxidation of Polyaromatic Compounds using RICO Chemistry
Nowicka, Ewa,Hickey, Niamh W.,Sankar, Meenakshisundaram,Jenkins, Robert L.,Knight, David W.,Willock, David J.,Hutchings, Graham J.,Francisco, Manuel,Taylor, Stuart H.
supporting information, p. 12359 - 12369 (2018/08/29)
Ruthenium-ion-catalyzed oxidation (RICO) of polyaromatic hydrocarbons (PAHs) has been studied in detail using experimental and computational approaches to explore the reaction mechanism. DFT calculations show that regioselectivity in these reactions can be understood in terms of the preservation of aromaticity in the initial formation of a [3+2] metallocycle intermediate at the most-isolated double bond. We identify two competing pathways: C?C bond cleavage leading to a dialdehyde and C-H activation followed by H migration to the RuOx complex to give diketones. Experimentally, the oxidation of pyrene and phenanthrene has been carried out in monophasic and biphasic solvent systems. Our results show that diketones are the major product for both phenanthrene and pyrene substrates. These diketone products are shown to be stable under our reaction conditions so that higher oxidation products (acids and their derivatives) are assigned to the competing pathway through the dialdehyde. Experiments using 18O-labelled water do show incorporation of oxygen from the solvents into products, but this may take place during the formation of the reactive RuO4 species rather than directly during PAH oxidation. When the oxidation of pyrene is carried out using D2O, a kinetic isotope effect (KIE) is observed implying that water is involved in the rate-determining step leading to the diketone products.
Oxidation of Polynuclear Aromatic Hydrocarbons using Ruthenium-Ion-Catalyzed Oxidation: The Role of Aromatic Ring Number in Reaction Kinetics and Product Distribution
Nowicka, Ewa,Clarke, Tomos J.,Sankar, Meenakshisundaram,Jenkins, Robert L.,Knight, David W.,Golunski, Stanislaw,Hutchings, Graham J.,Willock, David J.,Francisco, Manuel,Taylor, Stuart H.
, p. 655 - 662 (2018/01/26)
Oxidation of aromatic hydrocarbons with differing numbers of fused aromatic rings (2–5), have been studied in two solvent environments (monophasic and biphasic) using ruthenium-ion-catalyzed oxidation (RICO). RICO reduces the aromaticity of the polyaromatic core of the molecule in a controlled manner by selective oxidative ring opening. Moreover, the nature of the solvent system determines the product type and distribution, for molecules with more than two aromatic rings. Competitive oxidation between substrates with different numbers of aromatic rings has been studied in detail. It was found that the rate of polyaromatic hydrocarbon oxidation increases with the number of fused aromatic rings. A similar trend was also identified for alkylated aromatic hydrocarbons. The proof-of-concept investigation provides new insight into selective oxidation chemistry for upgrading of polyaromatic molecules.
Room-temperature synthesis of pharmaceutically important carboxylic acids bearing the 1,2,4-oxadiazole moiety
Tarasenko, Marina,Duderin, Nikolay,Sharonova, Tatyana,Baykov, Sergey,Shetnev, Anton,Smirnov, Alexey V.
supporting information, p. 3672 - 3677 (2017/08/23)
An efficient and mild one-pot protocol has been developed for the synthesis of 1,2,4-oxadiazoles via the reaction of amidoximes with dicarboxylic acid anhydrides in a NaOH/DMSO medium. The method allows the synthesis of diversely substituted carboxylic acids bearing the 1,2,4-oxadiazole motif, – a popular building block for pharmaceutical research, in moderate to excellent yields. The reaction scope includes aromatic and heteroaromatic amidoximes as well as five-, six- and seven-membered anhydrides. The advantages of this procedure are proven gram-scalability and the use of inexpensive starting materials, which from a process chemistry point of view are essential for future industrial applications.
Design, synthesis and insecticidal activity of biphenyl-diamide derivatives
Liu, Ye,Lei, Chao,Xu, Xiao-Yong,Shao, Xu-Sheng,Li, Zhong
, p. 321 - 324 (2016/03/16)
Diamides acting on insect ryanodine receptors are an intensive research area now. In order to search for novel candidates, a series of diamides containing biphenyl substructure were designed and synthesized. Their insecticidal activities against armyworms (Mythimna sepatara) and aphis (Aphis craccivora) were screened. The compounds with 3,5-dichloro-4-(1,1,2,2-tetrafluoroethoxy)phenyl substituent were found to be insecticidal to armyworms with the similar symptoms to poisoning by flubendiamide. In this research, we presented a novel type of diamide insecticide as a lead compound for further optimization.
Reduction of 1,2-dicarbonyl compounds and of their N-phenylimine derivatives by sodium cyanide under aprotic conditions
Batanero, Belen,Hamrouni, Kaouthar,Barba, Fructuoso,Barba, Isidoro,Boujlel, Khaled,Benkhoud, Mohamed Lamine
, p. 1284 - 1288 (2015/12/12)
Some aromatic 1,2-dicarbonyl compounds, i.e. 9,10-phenanthrenequinone, acenaphthenequinone and benzil, and their corresponding N-phenyl monoimines, have been reduced, using dry acetonitrile as the solvent, in the presence of sodium cyanide as a reducing agent. Comparative potentiostatic preparative-scale electrolysis is described.
Organocatalytic aerobic oxidative cleavage of cyclic 1,2-diketones
Gundala, Sivaji,Fagan, Claire-Louise,Delany, Eoghan G.,Connon, Stephen J.
supporting information, p. 1225 - 1228 (2013/07/19)
The first organocatalytic aerobic oxidative cleavage of cyclic 1,2-diketones is reported. The reaction occurs in either aqueous or alcoholic media and is promoted by a simple N-heterocyclic carbene catalyst derived from a 1,2,4-triazolium ion. No strong oxidants are required. The application of the process in a one-pot synthesis of a cyclic anhydride is also possible. Georg Thieme Verlag Stuttgart. New York.
Synthesis of unstable cyclic peroxides for chemiluminescence studies
Bartoloni, Fernando H.,De Oliveira, Marcelo A.,Augusto, Felipe A.,Ciscato, Luiz Francisco M. L.,Bastos, Erick L.,Baader, Wilhelm J.
, p. 2093 - 2103 (2013/04/24)
Cyclic four-membered ring peroxides are important high-energy intermediates in a variety of chemi and bioluminescence transformations. Specifically, a-peroxylactones (1,2-dioxetanones) have been considered as model systems for efficient firefly bioluminescence. However, the preparation of such highly unstable compounds is extremely difficult and, therefore, only few research groups have been able to study the properties of these substances. In this study, the synthesis, purification and characterization of three 1,2-dioxetanones are reported and a detailed procedure for the known synthesis of diphenoyl peroxide, another important model compound for the chemical generation of electronically excited states, is provided. For most of these peroxides, the complete spectroscopic characterization is reported here for the first time.
Photocatalytic degradation of polycyclic aromatic hydrocarbons in GaN:ZnO solid solution-assisted process: Direct hole oxidation mechanism
Kou, Jiahui,Li, Zhaosheng,Guo, Yong,Gao, Jun,Yang, Ming,Zou, Zhigang
experimental part, p. 48 - 54 (2010/10/01)
GaN:ZnO exhibits excellent activity for the photodegradation of PAHs, and the activity can be obviously improved by loading Pt. The degradation of PAHs in the system of GaN:ZnO is induced by the formation of holes. The holes generated then interact with PAHs to produce PAHs+, which is active enough to react with O2.
