- Electrochemical reduction of 3-phenyl-1,2-benzisoxazole 2-oxide on boron-doped diamond
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The bioreduction of N-oxide compounds is the basis for the mode of action of a number of biologically active molecules. These compounds are thought to act by forming a reactive oxygen species through an intracellular reduction and subsequent redox cycling process within the organism. With these results in mind, the preliminary investigation into the electrochemical reduction of the benzisoxazole 2-oxide ring system was undertaken, with the thought that this class of compounds would reduce in a similar fashion to other N-oxide heterocycles. The electrochemical reduction of 3-phenyl-1,2-benzisoxazole 2-oxide on boron-doped diamond was studied using cyclic and square wave voltammetry as well as controlled potential electrolysis and HPLC for qualitative identification of the reaction products. It was found that the reduction proceeded with an initial quasi-reversible one-electron reduction followed by the very fast cleavage of either the endocyclic or exocyclic N-O bond. Subsequent electron transfer and protonation resulted in an overall two-electron reduction and formation of the 2-hydroxyaryl oxime and benzisoxazole. These results are analogous to those observed in the electrochemical reduction of other heterocyclic N-oxides albeit the reduction of the benzisoxazole N-oxides takes place at a more negative potential. However, these encouraging results warrant further investigation into the reduction potential of substituted benzisoxazole N-oxides as well as to elucidate and characterize the nature of the intermediate species involved.
- Kociolek, Martin,Bennett, Jason,Casbohm, Jerry
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p. 540 - 544
(2014/06/09)
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- Benzisoxazole 2-oxides as novel UV absorbers and photooxidation inhibitors
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Compounds with strong absorptions in the ultraviolet (UV) region of the spectrum, particularly the UVA and UVB, have seen much interest as UV screeners or absorbers in a wide variety of commercial products. A series of benzisoxazole 2-oxides have been synthesized and characterized by UV-vis spectroscopy. A number of derivatives have been shown to posses moderate to strong molar absorption coefficients in the UVB range (ca. 300 nm), the strongest being those derived from benzophenones. Three other derivatives containing additional electron withdrawing groups showed strong molar absorption coefficients in the UVA (ca. 340 nm). Solvent effects on the parent derivatives show changes in the molar absorption coefficients with little changes in the λmax values. Preliminary studies of these compounds as potential additives to prevent photooxidation of polystyrene showed considerable inhibition of polymer degradation with the parent unsubstituted benzisoxazole 2-oxide compounds being the most effective. Copyright 2013 John Wiley & Sons, Ltd. A series of benzisoxazole 2-oxides have been shown to posses moderate to strong molar absorption coefficients in the UVB range (ca. 300 nm) and three others with strong absorptions on the UVA (ca. 340 nm). Solvent effects of the parent derivatives show changes in the molar absorption coefficients with little changes in the λmax values. Preliminary studies of these compounds as potential additives to prevent photooxidation of polystyrene showed considerable inhibition of polymer degradation. Copyright
- Kociolek, Martin George,Casbohm, Jerry S.
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p. 863 - 867
(2013/10/01)
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- From antiferromagnetic to ferromagnetic exchange in a family of oxime-based MnIII dimers: A magneto-structural study
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The reaction of Mn(ClO4)2·6H2O, a derivatised phenolic oxime (R-saoH2) and the ligand tris(2-pyridylmethyl)amine (tpa) in a basic alcoholic solution leads to the formation of a family of cluster compounds of general formula [Mn III2O(R-sao)(tpa)2](ClO4) 2 (1, R = H; 2, R = Me; 3, R = Et; 4, R = Ph). The structure is that of a simple, albeit asymmetric, dimer of two MnIII ions bridged through one μ-O2- ion and the -N-O- moiety of the phenolic oxime. Magnetometry reveals that the exchange interaction between the two Mn III ions in complexes 1, 3 and 4 is antiferromagnetic, but that for complex 2 is ferromagnetic. A theoretically developed magneto-structural correlation reveals that the dominant structural parameter influencing the sign and magnitude of the pairwise interaction is the dihedral Mn-O-N-Mn (torsion) angle. A linear correlation is found, with the magnitude of J varying significantly as the dihedral angle is altered. As the torsion angle increases the AF exchange decreases, matching the experimentally determined data. DFT calculations reveal that the dyzπ*dyz interaction decreases as the dihedral angle increases leading to ferromagnetic coupling at larger angles.
- Barros, Wdeson P.,Inglis, Ross,Nichol, Gary S.,Rajeshkumar, Thayalan,Rajaraman, Gopalan,Piligkos, Stergios,Stumpf, Humberto O.,Brechin, Euan K.
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p. 16510 - 16517
(2013/12/04)
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- Synthesis of 1,2-benzisoxazole 2-oxides
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(Chemical Equation Presented) A series of 2-hydroxyaryl ketoximes were converted to the corresponding 1,2- benzisoxazole 2-oxides by treatment with iodobenzene diacetate (in acetic acid or methanol) or N-chlorosuccinimide in water. Both methods gave moderate to excellent yields for a variety of substituted oximes under mild conditions within short reaction times. The latter method has the advantages of an aqueous solvent and lack of halogenated organic by-products. Copyright Taylor & Francis Group, LLC.
- Kociolek, Martin G.,Hoermann, Olivia
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p. 2632 - 2638
(2012/08/08)
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