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Henriksen, Lars; Jakobsen, Søren

doi:10.1039/b107688b

Cited by 5 publications

(3 citation statements)

References 12 publications

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“…One alternative to the selenoxide elimination generating the active catalyst with 1-SePh is that oxidation of 1-SePh to 1-Se(  O)Ph is responsible for the induction period observed in Figure and that 1-Se(  O)Ph is the actual catalyst in the system. It is known that selenoxides catalyze the decomposition of H 2 O 2 to give O 2 and H 2 O, indicating that selenoxides interact with H 2 O 2 in solution.…”

Section: Resultsmentioning

confidence: 99%

“…The selenoxide group appears to be a highly reactive catalytic group for the activation of H 2 O 2 in addition to its known catalase-like ability to decompose H 2 O 2 . We are currently examining stereoelectronic effects on the efficiency and reactivity of selenoxide catalysts, and we are designing polyfunctional, dendrimeric selenoxides that cannot undergo selenoxide elimination reactions.…”

Section: Discussionmentioning

confidence: 99%

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Dendrimeric Organochalcogen Catalysts for the Activation of Hydrogen Peroxide: Origins of the “Dendrimer Effect” with Catalysts Terminating in Phenylseleno Groups

2003

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Several scenarios were evaluated to explain the large "dendrimer effect" observed in the bromination of cyclohexene with H(2)O(2) and NaBr catalyzed by the addition of Frechét-type dendrimers terminating in -O(CH(2))(3)SePh groups. Although phenylseleninic acid was an efficient catalyst for the oxidation of NaBr with H(2)O(2), first-order rate constants for the selenoxide elimination were too small to produce PhSeO(2)H at a rate sufficient to explain the rates of catalysis and no dendrimer effect was observed in the rates of selenoxide elimination. An induction period was observed using 1-SePh as a catalyst for the oxidation of Br(-) with H(2)O(2). The addition of preformed selenoxide 1-Se(=O)Ph gave immediate catalysis with no induction period. However, rates of oxidation of the selenides with H(2)O(2) under homogeneous or biphasic conditions or with t-BuOOH under homogeneous conditions were too slow to account for the rates of catalysis, and no dendrimer effect was observed in the rates of oxidation. The primary oxidant for converting selenides to selenoxides was "Br(+)" produced initially by the uncatalyzed background reaction of H(2)O(2) with NaBr and then produced catalytically following formation of selenoxide groups. Autocatalysis is observed, and the rate of oxidation increases with the number of SePh groups. Autocatalysis is the source of the large dendrimer effect observed with the SePh series of catalysts.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Dendrimeric Organochalcogen Catalysts for the Activation of Hydrogen Peroxide: Origins of the “Dendrimer Effect” with Catalysts Terminating in Phenylseleno Groups

2003

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“…When selenoxide 8 was treated with H 2 O 2 , the 77 Se NMR spectrum showed two signals at δ 882 and 879. The intensity of the signal at δ 882 decreased with time relative to the selenoxide signal at δ 879 associated with gas evolution (presumably O 2 ), perhaps from decomposition of either H 2 O 2 or 4 (δ 882), whose initial concentration would decrease with time and H 2 O 2 concentration . No benzeneseleninic acid (PhSeO 2 H, 77 Se NMR: δ 1218) was detected throughout the experiments, indicating that selenoxide 8 was robust under the conditions of reaction (see the SI).…”

mentioning

confidence: 99%

GPx-Like Activity of Selenides and Selenoxides: Experimental Evidence for the Involvement of Hydroxy Perhydroxy Selenane as the Active Species

et al. 2011

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The reaction mechanism of the GPx-like oxidation of PhSH with H(2)O(2) catalyzed by selenoxides proceeds via formation of the hydroxy perhydroxy selenane, which is a stronger oxidizing agent than selenoxide. A hydroxy perhydroxy selenane intermediate was observed by electrospray ionization mass spectrometry and (77)Se NMR spectroscopy in reactions of selenoxide 8 with H(2)O(2).The initial velocity of oxidation of PhSH by H(2)O(2) with selenoxide 8 is 4 orders of magnitude higher than that of 8 without peroxide. Selenoxide 8 is not reduced to selenide 6 by PhSH in the presence of H(2)O(2). While electronic substituent effects have minimal impact on the catalytic performance of selenoxides, chelating groups increase the rate of catalysis.

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50 Years of Organoselenium Chemistry, Biochemistry and Reactivity: Mechanistic Understanding, Successful and Controversial Stories

Madabeni,

Bortoli,

Nogara

et al. 2024

Chemistry A European J

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In 1973, two major discoveries changed the face of selenium chemistry: the identification of the first mammal selenoenzyme, glutathione peroxidase 1, and the discovery of the synthetic utility of the so‐called selenoxide elimination. While the chemical mechanism behind the catalytic activity of glutathione peroxidases appears to be mostly unveiled, little is known about the mechanisms of other selenoproteins and, for some of them, even the function lies in the dark. In chemistry, the capacity of organoselenides of catalyzing hydrogen peroxide activation for the practical manipulation of organic functional groups has been largely explored, and some mechanistic details have been clearly elucidated. As a paradox, despite the long‐standing experience in the field, the nature of the active oxidant in various reactions still remains matter of debate. While many successes characterize these fields, the pharmacological use of organoselenides still lacks any true application, and while some organoselenides were found to be non‐toxic and safe to use, to date no therapeutically approved use was granted. In this review, some fundamental and chronologically aligned topics spanning organoselenium biochemistry, chemistry and pharmacology are discussed, focusing on the current mechanistic picture describing their activity as either bioactive compounds or catalysts.

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Abstract: The stereospecific oxidation of hydrazine into cis-diimide and the catalytic disproportionation of hydrogen peroxide effected by selenoxides are suggested to involve a dissociative cycloelimination from an intermediary selenurane.

Cited by 5 publications

References 12 publications

Dendrimeric Organochalcogen Catalysts for the Activation of Hydrogen Peroxide: Origins of the “Dendrimer Effect” with Catalysts Terminating in Phenylseleno Groups

Dendrimeric Organochalcogen Catalysts for the Activation of Hydrogen Peroxide: Origins of the “Dendrimer Effect” with Catalysts Terminating in Phenylseleno Groups

GPx-Like Activity of Selenides and Selenoxides: Experimental Evidence for the Involvement of Hydroxy Perhydroxy Selenane as the Active Species

50 Years of Organoselenium Chemistry, Biochemistry and Reactivity: Mechanistic Understanding, Successful and Controversial Stories

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