7560-60-3Relevant academic research and scientific papers
Sulfoxidation with hydrogen peroxide catalyzed by [SeO 4{WO(O2)2}2]2-
Kamata, Keigo,Hirano, Tomohisa,Ishimoto, Ryo,Mizuno, Noritaka
, p. 5509 - 5518 (2010)
The selenium-containing dinuclear peroxotungstate, [(n-C4H 9)4N]2[SeO4{WO(O2) 2}2] (I), acts as a homogeneous catalyst for the selective oxidation of various kinds of cyclic mono- and disulfides with 30% aqueous H2O2. The cyclic disulfides were selectively oxidized to the corresponding monosulfoxides with one equivalent of H2O 2 with respect to the sulfides. In the presence of two equivalents of H2O2, the oxidation of dibenzothiophene gave the corresponding sulfone in 98% yield under the mild conditions. The negative Hammett ρ value (-0.62) for the competitive oxidation of p-substituted thioanisoles and the low XSO (XSO = (nucleophilic oxidation)/(total oxidation)) value of 0.14 for the I-catalyzed oxidation of thianthrene 5-oxide (SSO) revealed that I is a strong electrophilic oxidant. The reactivities of the di- and tetranuclear peroxotungstates with XO 4n- ligands (X = Se(vi), As(v), P(v), S(vi), and Si(iv)) were strongly dependent on the kinds of hetero atoms. The reaction rates for the sulfoxidation decreased with an increase in the XSO values and a peroxotungstate with a stronger electrophilicity was more active for the sulfoxidation. The kinetic and mechanistic investigations showed that the electrophilic attack of the peroxo oxygen at the sulfur atom is a key step in the sulfoxidation. The computational investigation supported the high chemoselectivitiy for the sulfoxidation of diallyl sulfide.
Photoredox catalysis for oxygenation/deoxygenation between sulfides and sulfoxides by visible-light-responsive polyoxometalates
Suzuki, Kosuke,Jeong, Jinu,Yamaguchi, Kazuya,Mizuno, Noritaka
, p. 1014 - 1021 (2016/02/19)
In this paper, we report the unique visible-light-responsive photoredox catalysis of a divacant lacunary silicotungstate TBA4H4[γ-SiW10O36] (SiW10) for functional group transformations of sulfur-containing compounds; namely, (i) aerobic oxygenation of sulfides to sulfoxides and (ii) deoxygenation of sulfoxides to sulfides. In the presence of suitable additives, such as Ce3+ (electron transfer mediator for oxygenation) and an alcohol (electron and proton donor for deoxygenation), SiW10 shows visible-light-induced charge transfers by using the newly formed highest occupied molecular orbitals derived from the coordinating Ce3+ or alcohol at the vacant site of SiW10. Consequently, oxygenation of sulfides and deoxygenation of sulfoxides can selectively proceed by irradiation with visible light (λ > 400 nm) to afford the corresponding desired products in high yields. The SiW10 photocatalysts can readily be recovered and reused for these transformations. Based on evidence from several experiments, the roles of the additives as well as the reaction mechanisms for these transformations are also discussed.
Polyoxomolybdate-Calix[4]arene Hybrid: A Catalyst for Sulfoxidation Reactions with Hydrogen Peroxide
Meninno, Sara,Parrella, Alessandro,Brancatelli, Giovanna,Geremia, Silvano,Gaeta, Carmine,Talotta, Carmen,Neri, Placido,Lattanzi, Alessandra
supporting information, p. 5100 - 5103 (2015/11/03)
An easily accessible polyoxomolybdate-calix[4]arene hybrid 1 has been synthesized and applied as a heterogeneous catalyst in the sulfoxidation of thioethers to sulfoxides and to sulfones under strictly stoichiometric amounts of 30% H2O2 in CH3CN as the solvent. This study represents the first promising example of successful employment of calixarenes-polyoxometalate (POM) hybrid materials in the area of catalytic oxidations.
Synthesis and oxidation catalysis of a Ti-substituted phosphotungstate, and identification of the active oxygen species
Takahashi, Eri,Kamata, Keigo,Kikukawa, Yuji,Sato, Sota,Suzuki, Kosuke,Yamaguchi, Kazuya,Mizuno, Noritaka
, p. 4778 - 4789 (2015/10/05)
In this paper, we report the synthesis of a Ti-substituted phosphotungstate, TBA6[(γ-PW10O36)2Ti4(μ-O)2(μ-OH)4] (I, TBA = tetra-n-butylammonium), and its application to H2O2-based oxidation. Firstly, an organic solvent-soluble dilacunary phosphotungstate precursor, TBA3[γ-PW10O34(H2O)2] (PW10), has been synthesized. By the reaction of PW10 and TiO(acac)2 (acac = acetylacetonate) in an organic medium (acetonitrile), I can be obtained. Compound I possesses a tetranuclear Ti core which can effectively activate H2O2 and shows high catalytic performance for several oxidation reactions, such as epoxidation of alkenes, oxygenation of sulfides, oxidative bromination of unsaturated compounds, and hydroxylation of anisole, giving the corresponding oxidation products with high efficiencies and selectivities. The catalytic performance of I is much superior to those of previously reported Ti-substituted polyoxometalates. In addition, I is highly durable during catalysis and can be reused several times while keeping its high catalytic performance. Furthermore, we have successfully isolated the truly catalytically active species for the present I-catalyzed oxidation, TBA6[(γ-PW10O36)2Ti4(μ-η2:η2-O2)4] (II), and its anion structure has been determined by X-ray crystallographic analysis. All of the four Ti2-μ-η2:η2-peroxo species in II are active for stoichiometric oxidation (without H2O2), and II is included in the catalytic cycle for I-catalyzed oxidation.
Highly efficient oxidation of sulfides with hydrogen peroxide catalyzed by [SeO4{WO(O2)2}2]2-
Kamata, Keigo,Hirano, Tomohisa,Mizuno, Noritaka
supporting information; experimental part, p. 3958 - 3960 (2010/01/06)
By using the selenium-containing dinuclear peroxotungstate at 0.005-0.1 mol%, various kinds of sulfides could be converted into the corresponding sulfoxides or sulfones in excellent yields with one or two equivalents of H 2O2 with respect to the sulfide, respectively.
An efficient solvent free catalytic oxidation of sulfides to sulfoxides with hydrogen peroxide catalyzed by a binaphthyl-bridged Schiff base titanium complex
De Rosa, Margherita,Lamberti, Marina,Pellecchia, Claudio,Scettri, Arrigo,Villano, Rosaria,Soriente, Annunziata
, p. 7233 - 7235 (2007/10/03)
A titanium binaphthyl-bridged Schiff base complex proved to be an efficient catalyst for the hydrogen peroxide oxidation of aromatic and aliphatic sulfides to the corresponding sulfoxides in satisfactory yields under solvent-free conditions.
[γ-1,2-H2SiV2W10O40] immobilized on surface-modified SiO2 as a heterogeneous catalyst for liquid-phase oxidation with H2O2
Kasai, Jun,Nakagawa, Yoshinao,Uchida, Sayaka,Yamaguchi, Kazuya,Mizuno, Noritaka
, p. 4176 - 4184 (2007/10/03)
An organic-inorganic hybrid support has been synthesized by covalently anchoring an N-octyldihydroimidazolium cation fragment onto SiO2 (denoted as 1-SiO2). This modified support was characterized by solid-state 13C, 29Si, and 31P NMR spectroscopy, IR spectroscopy, and elemental analysis. The results showed that the structure of the dihydroimidazolium skeleton is preserved on the surface of SiO2. The modified support can act as a good anion exchanger, which allows the catalytically active polyoxometalate anion [γ-1,2-H 2SiV2W10O40]4- (I) to be immobilized onto the support by a stoichiometric anion exchange (denoted as I/1-SiO2). The structure of anion I is preserved after the anion exchange, as confirmed by IR and 51V NMR spectroscopy. The catalytic performance for the oxidation of olefins and sulfides, with hydrogen peroxide (only one equivalent with respect to substrate) as the sole oxidant, was investigated with I/1-SiO2. This supported catalyst shows a high stereospecificity, diastereoselectivity, regioselectivity, and a high efficiency of hydrogen peroxide utilization for the oxidation of various olefins and sulfides without any loss of the intrinsic catalytic nature of the corresponding homogeneous analogue of I (i.e., the tetra-n-butylammonium salt of I, TBA-I), although the rates decreased to about half that with TBA-I. The oxidation can be stopped immediately by removal of the solid catalyst, and vanadium and tungsten species' can hardly be found in the filtrate after removal of the catalyst. These results rule out any contribution to the observed catalysis from vanadium and tungsten species that leach into the reaction solution, which means that the observed catalysis is truly heterogeneous in nature. In addition, the catalyst is reusable for both epoxidation and sulfoxidation without any loss of catalytic performance.
Transfert d'oxygene sur les thioethers a partir d'un sel d'oxaziridinium
Hanquet, Gilles,Lusinchi, Xavier
, p. 5299 - 5302 (2007/10/02)
The oxaziridinium salt 1 derived from dihydroisoquinolin is an oxygen transfer reagent to thioethers leading either to sulfoxides with a good selectivity when used in stoichiometric amounts, or to sulfones when used in excess (2 eq.).These reactions may be performed with an oxaziridinium salt prepared in situ by the reaction of oxone in alcaline medium with the corresponding iminium salt 2 in catalytic amount.
Catalytic Asymmetric Oxidation of Sulfides to Sulfoxides with tert-Butyl Hydroperoxide Using Binaphthol as a Chiral Auxiliary
Komatsu, Naoki,Hashizume, Masaya,Sugita, Toshio,Uemura, Sakae
, p. 4529 - 4533 (2007/10/02)
The asymmetric oxidation of sulfides to chiral sulfoxides in moderate yield with tert-butyl hydroperoxide (TBHP) was catalyzed very effectively by a titanium complex produced in situ from a titanium alkoxide and a chiral binaphthol.The highest enantioselectivities (up to 96percent ee) were obtained with commercial aqueous 70percent TBHP under atmospheric conditions at 25 deg C with 2.5 mol percent of the catalyst.The presence of more than 1.0 mol equiv of water relative to sulfide was essential for the oxidation, and it was found that the water was necessary not only to produce an effective catalyst for the highly enantioselective oxidation but also to maintain the catalytic activity of the titanium-binaphthol complex for a longer time.The nature of the solvent had a remarkable effect upon the ee of the sulfoxide.Carbon tetrachloride was proven to be the solvent of choice; the use of other chlorinated solvents resulted in low enantioselectivity.A moderate level of asymmetric amplification was observed in this catalytic system.From a mechanistic standpoint, it was revealed that the initial asymmetric oxidation to the chiral sulfoxide (ca. 50percent ee) is followed by the kinetic resolution of the sulfoxide; that is, the titanium-binaphthol complex catalyzes not only the asymmetric oxidation but also the subsequent kinetic resolution.
Persulfoxide and thiadioxirane intermediates in the reaction of sulfides and singlet oxygen
Watanabe, Yasumasa,Kuriki, Nobuo,Ishiguro, Katsuya,Sawaki, Yasuhiko
, p. 2677 - 2682 (2007/10/02)
Structure and reactivity of intermediates in the reaction of sulfides and singlet oxygen have been studied in aprotic solvents. It is shown that sulfoxides and sulfones are the major products at the initial stage of reaction. While the sulfoxide formation is more sensitive to the electronic of substituents, the steric retardation is more significant for sulfone formation. The effect of additives also revealed the sharp contrast between the two reactions; sulfoxide formation is accelerated significantly by protic or coordinating solvents, but sulfone formation is never affected by additives. 18O-tracer experiments indicated that the two oxygen in sulfones from one molecule. The activation energy for sulfone formation is positive in contrast to the sulfoxide case. These facts that thiadioxirane intermediates are surely formed via a nonpolar reaction in competition with persulfoxide formation. It is also shown that persulfoxides are stabilized by coordinating solvents as well as by protic ones. The stability of thiadioxiranes is discussed on the of theoretical calculations.
