- Visible light-promoted selective oxidation of sulfides to sulfoxides catalyzed by ruthenium porphyrins with iodobenzene diacetate
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Under visible light irradiation, the carbonyl ruthenium(II) porphyrin complexes efficiently catalyze the selective oxidation of sulfides to sulfoxides with iodobenzene diacetate [PhI(OAc)2] as the oxygen source. Various thioanisoles and allylic
- Chen, Tse-Hong,Yuan, Zhibo,Carver, Aaron,Zhang, Rui
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Read Online
- Spectroscopic characterization and reactivity studies of a mononuclear nonheme Mn(III)-hydroperoxo complex
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We report the first example of a mononuclear nonheme manganese(III)- hydroperoxo complex derived from protonation of an isolated manganese(III)- peroxo complex bearing an N-tetramethylated cyclam (TMC) ligand, [Mn III(TMC)(OOH)]2+. T
- So, Hee,Park, Young Jun,Cho, Kyung-Bin,Lee, Yong-Min,Seo, Mi Sook,Cho, Jaeheung,Sarangi, Ritimukta,Nam, Wonwoo
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- VpStyA1/VpStyA2B of variovorax paradoxus EPS: An aryl alkyl sulfoxidase rather than a styrene epoxidizing monooxygenase
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Herein we describe the first representative of an E2-type two-component styrene monooxygenase of proteobacteria. It comprises a single epoxidase protein (VpStyA1) and a two domain protein (VpStyA2B) harboring an epoxidase (A2) and a FAD-reductase (B) doma
- Tischler, Dirk,Schwabe, Ringo,Siegel, Lucas,Joffroy, Kristin,Kaschabek, Stefan R.,Scholtissek, Anika,Heine, Thomas
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- Aerobic oxidation of sulfides to sulfoxides catalyzed by gold/manganese oxides
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Although selective oxidation of sulfides to sulfoxides with molecular oxygen is a difficult reaction due to the overoxidation to sulfone, manganese oxides were found to catalyze the aerobic oxidation of sulfides to sulfoxides in 1,2- dichlorobenzene at 10
- Taketoshi, Ayako,Concepcion, Patricia,Garcia, Hermenegildo,Corma, Avelino,Haruta, Masatake
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Read Online
- Catalyst-free visible light-mediated selective oxidation of sulfides into sulfoxides under clean conditions
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A facile and efficient visible-light-mediated method for directly converting sulfides into sulfoxides under clean conditions without using any photocatalysts is reported. This method exhibited favourable compatibility with functional groups and afforded a series of sulfoxides with high selectivity and yields. Moreover, in order to shed more light on such a transformation, detailed mechanism studies were carried out both experimentally and theoretically. The readily accessible, low-cost and eco-friendly nature of the developed method will endow it with attractive applications in chemical synthesis.
- Fan, Qiangwen,Zhu, Longwei,Li, Xuhuai,Ren, Huijun,Wu, Guorong,Zhu, Haibo,Sun, Wuji
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supporting information
p. 7945 - 7949
(2021/11/01)
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- Synergistic cooperative effect of CF3SO2Na and bis(2-butoxyethyl)ether towards selective oxygenation of sulfides with molecular oxygen under visible-light irradiation
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A safe, practical and eco-friendly method for the switchable synthesis of sulfoxides and sulfones through visible-light-initiated oxygenation of sulfides at ambient temperature under transition-metal-, additives-free and minimal solvent conditions. The synergistic catalytic efforts between CF3SO2Na and 2-butoxyethyl ether represents the key promoting factor for the reaction. This journal is
- Liu, Kai-Jian,Wang, Zheng,Lu, Ling-Hui,Chen, Jin-Yang,Zeng, Fei,Lin, Ying-Wu,Cao, Zhong,Yu, Xianyong,He, Wei-Min
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supporting information
p. 496 - 500
(2021/01/28)
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- Flow Electrosynthesis of Sulfoxides, Sulfones, and Sulfoximines without Supporting Electrolytes
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An efficient electrochemical flow process for the selective oxidation of sulfides to sulfoxides and sulfones and of sulfoxides toN-cyanosulfoximines has been developed. In total, 69 examples of sulfoxides, sulfones, andN-cyanosulfoximines have been synthesized in good to excellent yields and with high current efficiencies. The synthesis was assisted and facilitated through a supporting electrolyte-free, fully automated electrochemical protocol that highlights the advantages of flow electrolysis.
- Amri, Nasser,Wirth, Thomas
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p. 15961 - 15972
(2021/07/20)
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- Sulfoxide and Sulfone Synthesis via Electrochemical Oxidation of Sulfides
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The oxidation of diaryl sulfides and aryl alkyl sulfides to the corresponding sulfoxides and sulfones under electrochemical conditions is reported. Sulfoxides are selectively obtained in good yield under a constant current of 5 mA for 10 h in DMF, while sulfones are formed as the major product under a constant current of 10 or 20 mA for 10 h in MeOH. The oxygen of both the sulfoxide and sulfone function is derived from water.
- Lee, Sunwoo,Park, Jin Kyu
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p. 13790 - 13799
(2021/10/12)
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- Method for preparing sulfoxide compound by catalyzing thioether compound to be oxidized by visible light excitation aqueous solution quantum dots
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The invention provides a method for preparing a sulfoxide compound through oxidation of a visible light excitation aqueous solution quantum dot catalytic thioether compound. Belong to photocatalysis synthesis technical field. To the method, an aqueous sol
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Paragraph 0027-0028
(2021/11/14)
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- Electrochemical Scalable Sulfoxidation of Sulfides with Molecular Oxygen and Water
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An efficient and chemoselective synthesis of sulfoxides through the electrooxidation of sulfides has been well developed. This protocol takes advantage of electricity as the terminal oxidant and of molecular oxygen and water as the oxygen atom sources. A variety of structurally diverse sulfoxide compounds are assembled in moderate to excellent yields. The scaled-up reactions at 6–20 mmol show the good practicability and application potential of this methodology. A possible free radical mechanism has been proposed to rationalize the reaction procedure.
- Cheng, Zhen,Gao, Xinglian,Yao, Lingling,Wei, Zhaoxin,Qin, Guohui,Zhang, Yonghong,Wang, Bin,Xia, Yu,Abdukader, Ablimit,Xue, Fei,Jin, Weiwei,Liu, Chenjiang
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p. 3743 - 3747
(2021/07/26)
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- A mild and chemoselective CALB biocatalysed synthesis of sulfoxides exploiting the dual role of AcOEt as solvent and reagent
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A mild, chemoselective and sustainable biocatalysed synthesis of sulfoxides has been developed exploiting CALB and using AcOEt with a dual role of more environmentally friendly reaction solvent and enzyme substrate. A series of sulfoxides, including the drug omeprazole, have been synthesised in high yields and with excellent E-factors.
- Anselmi, Silvia,Liu, Siyu,Kim, Seong-Heun,Barry, Sarah M.,Moody, Thomas S.,Castagnolo, Daniele
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supporting information
p. 156 - 161
(2021/01/14)
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- COVALENT ORGANIC FRAMEWORKS AND APPLICATIONS AS PHOTOCATALYSTS
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Described herein are covalent organic frameworks. The covalent organic frameworks have unique structural and physical properties, which lends them to be versatile in a number of different applications and uses. In one aspect, the covalent organic frameworks are composed of a plurality of fused aromatic groups and electron-deficient chromophores. The covalent organic frameworks are useful as photocatalysts in a number of different applications.
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Paragraph 00146; 00169
(2021/05/21)
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- Synthesis method of sulfoxide compound
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The invention discloses a method for preparing sulfoxide derivatives with industrial application value through substituted diaryl (heterocyclic aryl) and aryl (heterocyclic aryl) alkyl sulfide compounds. Under electrochemical reaction conditions, diaryl (heterocyclic aryl) and aryl (heterocyclic aryl) alkyl sulfide compounds which are wide in source and easy to prepare and have structural diversity are used as raw materials, lithium perchlorate (LiClO4) is used as an electrolyte, acetonitrile (CH3CN) is used as a solvent, and oxygen is used as an oxidizing agent to prepare the diaryl (heterocyclic aryl) and aryl (heterocyclic aryl) alkyl sulfoxide derivatives. Compared with reported preparation methods of sulfoxide derivatives, the preparation method disclosed by the invention is green, environment-friendly, safe, energy-saving, wide in substrate application range, good in compatibility of product functional groups, easy in obtaining of raw materials and simple and convenient to operate.
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Paragraph 0031-0033; 0065-0067
(2021/04/07)
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- Accessing Enantiopure Epoxides and Sulfoxides: Related Flavin-Dependent Monooxygenases Provide Reversed Enantioselectivity
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Enantiopure organic compounds are of major importance for the chemical and pharmaceutical industry. Flavin-dependent group E monooxygenases, composed of monooxygenase and reductase, are known to perform epoxidation of substituted alkenes as well as sulfoxidation in a regio- and enantioselective fashion. Group E is divided into styrene monooxygenases (SMO) and indole monooxygenases (IMO). Hitherto mainly SMOs have been characterized. In this study, we assayed 31 monooxygenases from both types, while 23 of which showed activity. They almost exclusively produced (S)-styrene oxide at high enantiomeric excess with maximum activities of 0.73 μmol min?1 mg?1 (kcat=0.54 s?1). In case of sulfoxidation, we found that the enantioselectivity is contrary between both types. IMOs preferably produce the (S)-enantiomer while SMOs have a tendency to produce the (R)-enantiomer. Sequence analysis and molecular docking of substrates allowed identifying fingerprint motives: SMO N46-V48-H50-Y73-H76-S96 and IMO S46-Q48-M50-V/I73-I76-A96. These form an essential part of the active site while the loop (AS44-51) interacts with the co-substrate and other amino acids direct the substrate. The motives clearly distinguish group E monooxygenases and define the enantioselectivity and thus direct biotechnological applications. Two-hour biotransformations with several sulfides in conjunction with upscale experiments (10 and 100 mg scale) resulted in the identification of promising candidates for the realization of biocatalytic processes.
- Heine, Thomas,Scholtissek, Anika,Hofmann, Sarah,Koch, Rainhard,Tischler, Dirk
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p. 199 - 209
(2019/11/13)
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- Improved catalytic performance of Co-MOF-74 by nanostructure construction
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Herein, we demonstrate for the first time the construction of hollow structural Co-MOF-74, whose shell is as thin as ~50 nm and assembled by nanoparticles ranging from 8 to 18 nm. It exhibits high performance for the photocatalytic oxidation of thioanisole and thermocatalytic cyanosilylation of aldehydes.
- Cheng, Xiuyan,Han, Buxing,Wan, Qiang,Zhang, Bingxing,Zhang, Fanyu,Zhang, Jianling,Zhang, Jing,Zheng, Lirong
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supporting information
p. 5995 - 6000
(2020/10/18)
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- Synthesis of an anthraquinone-containing polymeric photosensitizer and its application in aerobic photooxidation of thioethers
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Work on the synthesis of a polymeric photosensitizer and its application in the photooxidation of thioethers is reported herein. Firstly, the polymeric photosensitizer was designed and synthesized by the reaction of anthraquinone-2-carbonyl chloride (AQ-2-COCl) with poly(2-hydroxyethyl methacrylate) (PHEMA). Then, the visible light-induced photooxidation of thioethers under aerobic conditions was investigated. The results revealed that the reaction yielded sulfoxides highly chemoselectively in excellent yields with good substrate tolerance. Importantly, AQ-PHEMA could be easily recovered and reused more than 20 times without significant loss of the catalytic activity.
- Chen, Yang,Ding, Aishun,Hu, Jianhua
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p. 10661 - 10665
(2020/03/27)
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- Selective oxidation of (hetero)sulfides with molecular oxygen under clean conditions
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The development of eco-friendly and switchable catalytic systems for the conversion of a sole raw-material into distinct high-value products is a particularly attractive concept and a daunting synthetic challenge. In the present work, the first example of efficient and selective oxidation of sulfides to sulfones and sulfoxides using molecular oxygen under clean conditions was established.
- Liu, Kai-Jian,Deng, Ji-Hui,Yang, Jie,Gong, Shao-Feng,Lin, Ying-Wu,He, Jun-Yi,Cao, Zhong,He, Wei-Min
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supporting information
p. 433 - 438
(2020/02/13)
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- Oxidation of aromatic sulfides with molecular oxygen: Controllable synthesis of sulfoxides or sulfones
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The recent development of selective oxidation of aromatic sulfides with molecular oxygen was highlighted. The sulfoxides and sulfones could be obtained by simply switching the reaction media, i.e., bis(2-butoxyethyl)ether (BBE) or poly(ethylene glycol)dimethyl ether (PEGDME). The application of the high-boiling-point polyether as an initiator and green media can eliminate the need of large quantities of additives and volatile solvents. This strategy represents an economic and eco-friendly method that could find potential applications.
- Tang, Lili,Du, Kejie,Yu, Bing,He, Liangnian
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p. 2991 - 2992
(2020/03/24)
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- Design and Evaluation of Artificial Hybrid Photoredox Biocatalysts
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A pair of 9-mesityl-10-phenyl acridinium (Mes?Acr+) photoredox catalysts were synthesized with an iodoacetamide handle for cysteine bioconjugation. Covalently tethering of the synthetic Mes?Acr+ cofactors with a small panel of thermo
- Schwochert, Timothy D.,Cruz, Cole L.,Watters, John W.,Reynolds, Evan W.,Nicewicz, David A.,Brustad, Eric M.
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p. 3146 - 3150
(2020/08/05)
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- Formation and kinetic studies of manganese(IV)-oxo porphyrins: Oxygen atom transfer mechanism of sulfide oxidations
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Visible light irradiation of photo-labile porphyrin-manganese(III) chlorates or bromates (2) produced manganese(IV)-oxo porphyrins [MnIV(Por)(O)] (Por = porphyrin) (3) in three porphyrin ligands. The same oxo species 3 were also formed by chemical oxidation of the corresponding manganese(III) precursors (1) with iodobenzene diacetate, i.e. PhI(OAc)2. The systems under study include 5,10,15,20-tetra(pentafluorophenyl)porphyrin?manganese(IV)-oxo (3a), 5,10,15,20-tetra(2,6-difluorophenyl)porphyrin?manganese(IV)-oxo (3b), and 5,10,15,20-tetramesitylporphyrin?manganese(IV)-oxo (3c). As expected, complexes 3 reacted with thioanisoles to produce the corresponding sulfoxides and over-oxidized sulfones. The kinetics of oxygen atom transfer (OAT) reactions of these generated 3 with aryl sulfides were studied in CH3CN solutions. Second-order rate constants for sulfide oxidation reactions are comparable to those of alkene epoxidations and activated C[sbnd]H bond oxidations by the same oxo species 3. For a given substrate, the reactivity order for the manganese(IV)-oxo species was 3a > 3b > 3c, consistent with expectations on the basis of the electron-withdrawing capacity of the porphyrin macrocycles. Free-energy Hammett analyses gave near-linear correlations with σ values, indicating no significant positive charge developed at the sulfur during the oxidation process. The mechanistic results strongly suggest [MnIV(Por)(O)] reacts as a direct OAT agent towards sulfide substrates through a manganese(II) intermediate that was detected in this work. However, an alternative pathway that involves a disproportionation of 3 to form a higher oxidized manganese(V)-oxo species may be significant when less reactive substrates are present. The competition product studies with the Hammett correlation plot confirmed that the observed manganese(IV)-oxo species is not the true oxidant for the sulfide oxidations catalyzed by manganese(III) porphyrins with PhI(OAc)2.
- Klaine, Seth,Bratcher, Fox,Winchester, Charles M.,Zhang, Rui
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- Visible light generation of chromium(V)-oxo salen complexes and mechanistic insights into catalytic sulfide oxidation
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Visible light irradiation of the photo-labile salen-chromium(III) chlorate or bromate precursors produced salen-chromium(V)-oxo complexes that were spectroscopically and kinetically indistinguishable from those formed by chemical oxidation of chromium(III) salens with PhI(OAc)2. The photochemistry observed in this work is ascribed to the heterolytic cleavage of the O-X bond in the apical counterion that results in a two-electron oxidation of the metal to form the chromium(V)-oxo species. Second-order rate constants for oxidation reactions of 3 with organic substrates were determined under pseudo-first order condition, and particularly low level of reactivity for sulfide oxidations was observed. In this study, chromium(III) salen complexes effectively catalyzed the oxidation of aryl sulfides into sulfoxides with PhI(OAc)2 in the presence of a small amount of water. The competition product studies with the Hammett correlation plot indicated that the observed chromium(V)-oxo species is not likely to serve as the major oxidant for the sulfide oxidations catalyzed by chromium(III) salens with PhI(OAc)2.
- Dames, Angeline,Fung Lee, Ngo,Klaine, Seth,Zhang, Rui
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- Accurate Regulating of Visible-Light Absorption in Polyoxotitanate-Calix[8]arene Systems by Ligand Modification
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With use of a macrocyclic polyphenol, tert-butylcalix[8]arene (TBC[8]), as ligands, a series of TBC[8]-stabilized {Ti4O2}clusters, containing penta- and hexacoordinated Ti centers, were synthesized. Such complexes are "core-shell" shaped containing a {Ti4O2} core arranged in a zigzag fashion. While outer walls of the clusters are decorated by deprotonated TBC[8], their upper and lower surfaces can be modified by various O- or N-donor ligands, and the ratio of the penta- and hexacoordinated Ti(IV) centers in the {Ti4O2} core can be precisely regulated from 4:0, to 3:1, to 2:2, to 1:3, and finally to 0:4. The combined coordination of different ligands in the axial direction shows significant influence on the adsorption of the TBC[8]-Ti4 system in the visible-light region, and their absorption edge can be precisely regulated from 600 to 700 nm. The above structural functionalization in the TBC[8]-Ti4 system also tunes their photocatalytic H2 production activities and oxidative desulfurization ability. Thus, for the first time, by confining the polyoxotitanium cluster in macrocyclic molecules, we provide an example of understanding the structure-property relationship of titanium-oxygen materials by ligand modification.
- Liu, Chao,Yang, Xin-Xue,Yi, Xiao-Yi,Yu, Wei-Dong
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- Kinetic and mechanistic aspects of solid state, nanostructured porphyrin diacid photosensitizers in photooxidation of sulfides
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In continuation of our studies on the photocatalytic performance of porphyrin diacids, the kinetics and mechanisms of the photooxidation of para-substituted phenyl methyl sulfides (para X = H, CH3, OCH3, Cl, and F) catalyzed by a series of meso-tetra(aryl)porphyrins (aryl = phenyl, 2-chlorophenyl, 2-methylphenyl, 4-chlorophenyl, 4-methylphenyl and 4-methoxyphenyl) immobilized on Amberlyst 15 nanostructures (nanoAmb), H2T(2 or 4-X)PP@nanoAmb, are reported. The immobilization of porphyrins on the polymer was confirmed by diffuse reflectance UV-vis spectroscopy and EDX analysis. While little or no catalyst degradation was observed for a reaction time of ca. 3 h, the electron-deficient porphyrins (pseudo-first-order rate constants, kobs = 0.0049-0.012 min-1) showed faster second-order kinetics than the electron-rich ones (kobs = 2.30 × 10-5-9.92 × 10-4 min-1). The order of photocatalytic activity of the porphyrins approximately correlates with the singlet oxygen quantum yield (φΔ) of the photosensitizers. Diffuse reflectance UV-vis spectra of the immobilized porphyrins demonstrated a large red shift of the Soret and Q bands of the porphyrins which was more dominant in the case of H2T(4-OMe)PP. The weak overlap between the emission spectrum of the light source and the absorption spectrum of the latter was used to explain the low photocatalytic activity of H2T(4-OMe)PP@nanoAmb. The observation of a slope (ρ) of -2.80 for the oxidation of methyl phenyl sulfide and para-substituted phenyl methyl sulfides is in accord with the involvement of an electrophilic oxidation mechanism mediated by singlet oxygen species. H2TPP@naoAmb was recovered and reused at least five times without significant loss of the catalytic activity and detectable catalyst degradation, giving a turnover number of 5 × 5000 for five successive reactions. The catalyst was successfully used for large-scale (up to 6.6 mmol of sulfide per batch, in a 1:10000 catalyst-to-sulfide molar ratio) photooxidation of a wide range of sulfides to the corresponding sulfoxide in a water/acetonitrile solvent mixture.
- Nasrollahi, Rahele,Heydari-Turkmani, Akram,Zakavi, Saeed
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p. 1260 - 1272
(2019/04/17)
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- Synthetic and mechanistic investigations on manganese corrole-catalyzed oxidation of sulfides with iodobenzene diacetate
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Manganese corrole complexes catalyze the efficient oxidation of organic sulfides to sulfoxides with iodobenzene diacetate [PhI(OAc)2] as a mild oxygen source in the presence of small amounts of water. Various substituted thioanisoles can be eff
- Ranburger, Davis,Willis, Ben,Kash, Benjamin,Jeddi, Haleh,Alcantar, Christian,Zhang, Rui
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- Electrochemical oxidations of thioethers: Modulation of oxidation potential using a hydrogen bonding network
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A highly efficient chemo-selective electrochemical oxidation of thioethers to sulfoxides and sulfones was developed. The hydrogen bonding network generated from hexafluoro-2-propanol (HFIP) and acetic acid (AcOH) plays an important role in the modulation of oxidation potential. The hydrogen bonding network complexes strongly with the sulfoxide, making it less prone to further oxidation. Therefore, thioethers can be selectively electrochemically oxidized to sulfoxides and over-oxidization could be minimized. Moreover, this modulation of oxidization via hydrogen bonding was supported by density functional theory (DFT) calculations and cyclic voltammetry experiments.
- Liu, Shiwen,Chen, Bocheng,Yang, Yi,Yang, Yuhao,Chen, Qianjin,Zeng, Xiaojun,Xu, Bo
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- Switchable Synthesis of Aryl Sulfones and Sulfoxides through Solvent-Promoted Oxidation of Sulfides with O2/Air
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A practical and switchable method for the synthesis of aryl sulfones and sulfoxides via sulfide oxidation was developed. The chemoselectivities of products were simply controlled by reaction temperature using O2/air as the terminal oxidant and oxygen source. The broad substrate scope, easy realization of gram-scale production, and the simplification of a sulfide oxidation system render the strategy attractive and valuable.
- Cheng, Zhen,Sun, Pengchao,Tang, Ailing,Jin, Weiwei,Liu, Chenjiang
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supporting information
p. 8925 - 8929
(2019/11/14)
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- Identification of MsrA homologues for the preparation of (R)-sulfoxides at high substrate concentrations
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Here we report a methionine sulfoxide reductase A (MsrA) homologue with extremely high substrate tolerance and a wide substrate scope for the biocatalytic preparation of enantiopure sulfoxides. This MsrA homologue which was obtained from Pseudomonas alcaliphila (named paMsrA) showed good activity and enantioselectivity towards a series of aryl methyl/ethyl sulfoxides 1a-1k, with electron-withdrawing or electron-donating substituents at the aromatic ring. Chiral sulfoxides in the R configuration were prepared with approximately 50% of yield and up to 99% enantiomeric excess through the asymmetric reductive resolution of racemic sulfoxide catalyzed by the recombinant paMsrA protein. More importantly, kinetic resolution has been successfully accomplished with high enantioselectivity (E > 200) at initial substrate concentrations up to 320 mM (approximately 45 g L-1), which represents a great improvement in the aspect of the substrate concentration for the biocatalytic preparation of chiral sulfoxides.
- Yang, Jiawei,Wen, Yuanmei,Peng, Liaotian,Chan, Yu,Cheng, Xiaoling,Chen, Yongzheng
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p. 3381 - 3388
(2019/04/01)
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- Discovery of a New Family of Polyoxometalate-Based Hybrids with Improved Catalytic Performances for Selective Sulfoxidation: The Synergy between Classic Heptamolybdate Anions and Complex Cations
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A series of functional cation-regulated isopolymolybdate-based organic-inorganic hybrid compounds, Na2H2[Mo4O12(C8H17O5N)2]·10H2O (1), Na2[M(Bis-tris)(H2O)]2[Mo7O24]·10H2O [M = Cu, 2; Ni, 3; Co, 4; Zn, 5; Bis-tris = 2,2-Bis(hydroxymethyl)-2,2′,2″-nitrilotriethanol], and (NH4)2[M(Bis-tris)(H2O)]2[Mo7O24]·6H2O (M = Zn, 6; Cu, 7), were synthesized and characterized toward advanced molecular catalyst design. Compound 1 is a covalently bonded adduct, and its self-assembly process can be probed by electrospray ionization mass spectrometry (ESI-MS). Compounds 2-7 are polyoxometalate (POM)-based hybrids containing classic heptamolybdate anions and complex cations with Bis-tris ligands. All of these compounds showed remarkable catalytic effects for selective sulfide oxidation. To the best of our knowledge, compound 5 presents the best catalytic activity so far among the reported hybrid materials with common easily synthesized small-molecule POM clusters and also exhibits outstanding reliability. The conclusion of the catalytic effect is drawn from the results that Zn-based compounds have better catalytic effects than other transition-metal-containing compounds and the compound constructed by Na+ has higher catalytic activity than that constructed by NH4 +. The mechanism studies show that the improvements of the catalytic performance are caused by the synergy between classic heptamolybdate anions and complex cations. ESI-MS data and UV-vis spectra revealed that the POM anions can form intermediate peroxomolybdenum units during catalytic reaction. Further, the combination of the substrate thioanisole with complex cations was characterized by NMR experiments and UV-vis spectra. Thus, a new synergistic mechanism of anions and cations is proposed in which the activated thioanisole is used as a nucleophile to attack the peroxomolybdenum bonds, and this provides a new strategy in the design of reliable POM-based catalysts.
- Zhang, Yin,Yu, Wei-Dong,Li, Bin,Chen, Zheng-Fan,Yan, Jun
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supporting information
p. 14876 - 14884
(2019/11/05)
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- A novel catalytic system poly(1-vinyl-3-dodecylimidazolium tribromide)/TBN for the oxidation of sulfides to sulfoxides with air as oxidant
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A novel and recoverable polymeric ionic liquid, poly(1-vinyl-3-dodecylimidazolium tribromide) (Poly[VDIM]Br3), was successfully prepared and fully characterized. And a highly efficient metal-free catalytic system Poly[VDIM]Br3/tert-butyl nitrite was developed for the oxidation of sulfides. With air as oxidant, we have successfully achieved 19 kinds of sulfides selectively and efficiently oxidized to corresponding sulfoxides using this catalytic system at room temperature.
- Zhang, Hua,Qi, Linlin
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p. 3171 - 3174
(2018/07/13)
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- Selective Oxidation of Sulfides in Flow Chemistry
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A packed-bed reactor with oxone has been employed for selective oxidations of sulfur compounds. Various sulfides containing different functional groups are efficiently oxidized to the corresponding sulfoxides without formation of sulfones or other side products.
- Silva, Filipa,Baker, Alastair,Stansall, James,Michalska, Weronika,Yusubov, Mehkman S.,Graz, Michael,Saunders, Robert,Evans, Gareth J. S.,Wirth, Thomas
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supporting information
p. 2134 - 2137
(2018/05/31)
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- Aluminum(III) Chloride Promoted Oxygen Transfer: Selective Oxidation of Sulfides to Sulfoxides
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An efficient selective oxidation of sulfides to sulfoxides has been developed by means of AlCl 3 -promoted oxygen transfer from phenyliodine diacetate [PhI(OAc) 2 ]. AlCl 3 proved to be the optimalLewis acid for the activation of PhI(OAc) 2. Various substituted sulfides were selectively transformed into the corresponding sulfoxides in good to excellent yields (≤99%). The high efficiency, excellent functional-group compatibility, broad substrate scope, and mild conditions render the current transformation useful for the synthesis of sulfoxides.
- Xie, Yongtao,Li, Yuxin,Zhou, Sha,Zhou, Shaa,Zhang, Yan,Chen, Minggui,Li, Zhengming
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supporting information
p. 340 - 343
(2017/12/06)
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- Hollow Anatase TiO2 Octahedrons with Exposed High-Index {102} Facets for Improved Dye-Sensitized Photoredox Catalysis Activity
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The high activity of exposed facets and large surface area have significant effects on the performance of photocatalysts because most of the photoreactivity properties of materials are related to surface processes. The strategy of combining high-index facets and a hollow structure into one material will provide a new way for designing effective photocatalysts, possessing active exposed facets and a large surface area at the same time. However, fabricating one material with both high-index facets and a hollow structure is still a great challenge due to their thermodynamic instability. Here, hollow anatase TiO2 octahedrons exposed with high-index (102) facets (HTO-102) were successfully fabricated for the first time by a facile hydrothermal method using HF and H2O2 as morphology controlling agents. Compared with two other catalysts (a solid sharp octahedron with (101) facets (SSO-101) and a hollow sharp octahedron with (101) facets (HSO-101)), HTO-102 particles exhibit a better photochemical activity for the selective aerobic oxidation of organic sulfides under visible-light irradiation. Experimental results and theoretical calculations indicate that the excellent photocatalytic activity of HTO-102 particles is mainly due to the synergistic effects of its hollow structure and exposed high-index (102) facets.
- Wang, Fan,Sun, Liming,Li, Yanan,Zhan, Wenwen,Wang, Xiaojun,Han, Xiguang
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supporting information
p. 4550 - 4555
(2018/04/23)
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- Biocatalytic Preparation of Chiral Sulfoxides through Asymmetric Reductive Resolution by Methionine Sulfoxide Reductase A
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Here we report an environmentally friendly method for the preparation of chiral sulfoxides under high substrate concentration using recombinant methionine sulfoxide reductase A from Pseudomonas monteilii (pmMsrA) as a biocatalyst. Our results show that this enzyme can effectively accomplish the preparation of (R)-sulfoxides with approximately 50 % yield and 94–99 % enantiomeric excess through asymmetric reductive resolution of racemic sulfoxide. With the establishment of the enzyme regeneration system, the initial substrate concentration could be increased 40–100 times compared to our original report. The (R)-sulfoxides were obtained with high enantioselectivity under the substrate concentration up to 200 mm (approximately 32 g L?1), representing a quite high substrate concentration in biocatalytic preparation of chiral sulfoxides. Moreover, this system showed fairly good activity and enantioselectivity towards a series of ortho- and para-substituted phenyl methyl sulfoxides under high substrate concentration.
- Peng, Liaotian,Wen, Yuanmei,Chen, Yu,Yuan, Zhimei,Zhou, Yang,Cheng, Xiaoling,Chen, Yongzheng,Yang, Jiawei
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p. 3284 - 3290
(2018/06/04)
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- Electrochemical synthesis of methyl sulfoxides from thiophenols/thiols and dimethyl sulfoxide
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A new route for a one-pot synthesis of methyl sulfoxides from thiophenols/thiols and dimethyl sulfoxide using an electrochemical technique was developed. This protocol proceeded smoothly by employing electrons and hydrogen peroxide as clean oxidants, and a wide range of aromatic and aliphatic sulfoxides were synthesized in moderate to good yields.
- Du, Ke-Si,Huang, Jing-Mei
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supporting information
p. 1405 - 1411
(2018/03/27)
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- Insights from kinetic studies of photo-generated compound II models: Reactivity toward aryl sulfides
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Iron(IV)-oxo porphyrins [FeIV(Por)O] (Por = poprhyrin), commonly called compound II models, were produced in three electron-deficient ligands by visible light irradiation of highly photo-labile porphyrin-iron(III) bromates or chlorates. The kinetics of oxygen transfer atom (OAT) reactions with aryl sulfides by these photo-generated [FeIV(Por)O] (3) were studied in CH3CN solutions. The iron(IV)-oxo porphyrins under study include 5,10,15,20-tetra(2,6-dichlorophenyl)porphyrin-iron(IV)-oxo (3a), 5,10,15,20-tetra(2,6-difluorophenyl)porphyrin-iron(IV)-oxo (3b), and 5,10,15,20-tetra(pentafluorophenyl)porphyrin-iron(IV)-oxo (3c). As expected, complexes 3 were competent oxidants and reacted rapidly with thioanisoles to give the corresponding sulfoxides with minor over-oxidation sulfones. Apparent second-order rate constants determined under pseudo-first-order conditions for sulfide oxidation reactions are (9.8 ± 0.1) × 102–(3.7 ± 0.3) × 101 M?1 s?1, which are 3 to 4 orders of magnitude greater in comparison to those of alkene epoxidations and activated C–H bond oxidations by the same oxo species. Conventional Hammett analyses gave non-linear correlations, indicating no significant charge developed at the sulfur during the oxidation process. For a given substrate, the reactivity order for the iron(IV)-oxo species was 3c 3b 3a, which is inverted from expectations on the basis of the electron-withdrawing capacity of the porphyrin macrocycles. The absolute rate constants from kinetic studies provided insights into the transient oxidants in catalytic reactions under turnover conditions where actual reactive intermediates are not observable. Our kinetic and catalytic competition results strongly suggest that 3 may undergo a disproportionation reaction to form a higher oxidized iron(IV)-oxo porphyrin radical cations as the true oxidant.
- Lee, Ngo Fung,Patel, Dharmesh,Liu, Haiyan,Zhang, Rui
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- Kinetic resolution of phenyl methyl sulfoxides by mammalian methionine sulfoxide reductase A
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Chiral sulfoxides are widely used in organic synthesis as chiral auxiliaries. There are numerous strategies for the preparation of enantiomerically pure sulfoxides, based either on the enantioselective oxidation of sulphides or the enantiospecific reduction of sulfoxides. For both cases, bioconversion techniques have been developed and proposed for large-scale synthesis. Methionine sulfoxide reductase enzymes (MsrA and MsrB) catalyse the stereoselective conversion of methionine sulfoxide to methionine. MsrA can also catalyse the reduction of other exogenous sulfoxides, including p-tolyl methyl sulfoxide. However, the stereoselectivity towards this type of substrate is not yet well characterized. The activity and enantioselectivity of MsrA toward several aryl methyl sulfoxides is presented in this paper.
- Achilli, Cesare,Ciana, Annarita,Minetti, Giampaolo
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p. 4781 - 4782
(2017/11/29)
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- Metal- and additive-free oxygen-atom transfer reaction: an efficient and chemoselective oxidation of sulfides to sulfoxides with cyclic diacyl peroxides
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Metal- and additive-free oxidation of a series of sulfides/thioketones has been achieved using cyclic diacyl peroxides as mild oxygen sources. This protocol features simple manipulation, high chemo- and diastereoselectivity, and a broad substrate scope (up to 42 examples), tolerates many common functional groups, and is scalable and applicable to the late-stage sulfoxidation strategy. A preliminary mechanistic study by quantum mechanical calculations suggests that a single two-electron transfer process is energetically more favorable, and indicates the reactivity of cyclic diacyl peroxides distinct from conventional acyclic acyl peroxides.
- Gan, Shaoyan,Yin, Junjie,Yao, Yuan,Liu, Yang,Chang, Denghu,Zhu, Dan,Shi, Lei
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supporting information
p. 2647 - 2654
(2017/04/03)
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- 1,1,2,2-Tetrahydroperoxy-1,2-diphenylethane as new oxidant for chemoselective and catalyst free oxidation of sulfides to sulfoxides and sulfones
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A catalyst free and chemoselective oxidation of sulfides to sulfoxides or sulfones was developed using 1,1,2,2-tetrahydroperoxy-1,2-diphenylethane as a new oxidant. This scope has shown the achievement of various sulfoxides and sulfones which were obtained selectively in high yields at room temperature.
- Khosravi, Kaveh,Naserifar, Shirin,Mahmoudi, Boshra,Khalaji, Kobra
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p. 316 - 321
(2017/02/18)
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- Mn-Schiff base complex supported on magnetic nanoparticles: Synthesis, crystal structure, electrochemical properties and catalytic activities for oxidation of olefins and sulfides
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A novel, magnetically recoverable Mn-Schiff base catalyst has been prepared by the adsorption on silica-coated magnetic nanoparticles. X-ray crystallography studies reveal that the Mn-complex adopt a distorted octahedral six-coordinate configuration formed by the tetradentate Schiff base ligand and two oxygen atoms of acetate anion. The heterogeneous catalyst was characterized by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, vibrating sample magnetometer, thermo-gravimetric analysis, the energy-dispersive X-ray spectroscopy and FTIR spectroscopy. The catalyst loading on the magnetic support was determined by atomic absorption spectroscopy. Highly chemoselective oxidation of sulfides with excellent yield to the corresponding sulfoxides, and epoxidation of olefins in ethanol at room temperature were efficiently enhanced under the influence of the magnetically separable catalyst. The separation and recycling of the catalyst is simple, effective, and economic in this clean oxidation method. The electrochemical properties of the Mn-complex were investigated.
- Rayati, Saeed,Khodaei, Elham,Jafarian, Majid,Wojtczak, Andrzej
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p. 327 - 335
(2017/06/21)
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- Catalytic activity and electrochemical properties of Cu(II)-Schiff base complex encapsulated in the nanocavities of zeolite-Y for oxidation of olefins and sulfides
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Copper(II) complex of a Schiff base ligand (H2L) was synthesized, characterized, and encapsulated in the cavities of zeolite-Y by a fixed ligand method. The zeolite encapsulated metal complex (CuL-Y) was characterized using FT-IR, UV–Vis and atomic absorption spectroscopy, thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), scanning electron microscopy images (SEM), energy-dispersive X-ray spectroscopy (EDX), and Brunauer-Emmett-Teller (BET). The catalytic activity and electrochemical behavior of the encapsulated complex has been studied in the oxidation of a wide range of sulfides and olefins using H2O2 in ethanol. This heterogeneous catalytic system shows a dramatic increase in total turnover number (46,500) for oxidation of styrene. It could be readily reused for at least eight successive times without discernible activity and selectivity deterioration, which displays potential for practical applications.
- Rayati, Saeed,Khodaei, Elham,Jafarian, Majid
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p. 2736 - 2750
(2017/09/06)
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- Highly efficient and chemoselective oxidation of sulfides catalyzed by iron(III) corroles with iodobenzene diacetate
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Iron(III) corrole complexes catalyze the highly chemoselective oxidation of sulfides to sulfoxides with iodobenzene diacetate [PhI(OAc)2] as a mild oxygen source. Various substituted thioanisoles, vinyl sulfides, and hydroxyl sulfides can be ef
- Chen, Tse-Hong,Kwong, Ka Wai,Lee, Ngo Fung,Ranburger, Davis,Zhang, Rui
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- A chemoselective oxidation of sulfides to sulfoxides and sulfones using urea-2,2-dihydroperoxypropane as a novel oxidant
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Background: Sulfoxides and sulfones have been in the center of attention due to their wide range of promises in various approaches. The functional groups presented in these compounds serve as important building blocks in numerous natural, pharmeceutical and agricultural compounds. These deriatives have been prepared through a multitude of routes which were accompanied by several drawbacks. Therefore, there has been an ever-increasing interest to find a new methodology that leads to the production of these compounds via an environmentally benign path bringing about high yields. Recently, gem-dihydroperoxides have attracted much attention due to their oxidizing power and they have been utilized in several oxidation processes. Methods: We carried out a chemoselective oxidation of sulfides to sulfoxides and sulfones on treatment with urea-2,2-dihydroperoxypropane, a solid oxidant composed of equal amounts of 2,2-dihydroperoxypropane and urea, using THF as the solvent under catalyst-free conditions at room temprature. Results: Sulfides possessing a variety of substitutions namely dialkyl, diaryl, ally l and alkyl-aryl were subjected to the optimized reaction conditions and they could successfully afford different amounts of sulfoxides and sulfones depending on the amount of the oxidant utilized. Based on the results, electron-donating groups accelerated the reaction while electron-withdrawing substituents lowered the reactivity. Conclusion: Urea-2,2-dihydroperoxypropane as a solid oxidant which can be stored for several months without any loss in its activity has proved its capability to oxidize sulfides to sulfoxides and sulfones under catalyst-free and mild conditions. This approach is a cost-effective and environmentally benign methodology via which the products have been synthesized in high yields and short reaction times.
- Khosravi, Kaveh,Naserifar, Shirin,Asgari, Atefeh
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p. 749 - 756
(2017/02/05)
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- Chemoselective Oxidation of Sulfides to Sulfoxides with Urea-Hydrogen Peroxide Complex Catalysed by Diselenide
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A highly selective catalytic oxidation system has been developed for the conversion of sulfides into the corresponding sulfoxides using urea-hydrogen peroxide as stoichiometric oxidant in the presence of a catalytic quantity of diphenyl diselenide.
- Bulman Page, Philip C.,Buckley, Benjamin R.,Elliott, Claire,Chan, Yohan,Dreyfus, Nicolas,Marken, Frank
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supporting information
p. 80 - 82
(2015/12/26)
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- Visible-Light-Induced Photoredox Catalysis of Dye-Sensitized Titanium Dioxide: Selective Aerobic Oxidation of Organic Sulfides
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TiO2 photoredox catalysis has recently attracted much interest for use in performing challenging organic transformations under mild reaction conditions. However, the reaction scheme is hampered by the fact that TiO2 can only be excit
- Lang, Xianjun,Zhao, Jincai,Chen, Xiaodong
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p. 4697 - 4700
(2016/04/19)
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- Metal-Free, Phosphonium Salt-Mediated Sulfoximination of Azine N-Oxides: Approach for the Synthesis of N-Azine Sulfoximines
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Herein, we report a simple and metal-free method for the synthesis of N-azine sulfoximines by the nucleophilic substitution of azine N-oxides with NH-sulfoximines. The present method works at room temperature with wide functional group compatibility and gives several unprecedented N-azine sulfoximines. The reaction conditions were also found suitable with enantiopure substrates and furnished products without any racemization. It also finds an application in the sulfoximination of azine-based functional molecules such as 2,2′-bipyridine, 1,10-phenanthroline, and quinine.
- Aithagani, Sravan Kumar,Kumar, Mukesh,Yadav, Mahipal,Vishwakarma, Ram A.,Singh, Parvinder Pal
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p. 5886 - 5894
(2016/07/23)
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- Reactivity of a Cobalt(III)-Hydroperoxo Complex in Electrophilic Reactions
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The reactivity of mononuclear metal-hydroperoxo adducts has fascinated researchers in many areas due to their diverse biological and catalytic processes. In this study, a mononuclear cobalt(III)-peroxo complex bearing a tetradentate macrocyclic ligand, [C
- Shin, Bongki,Sutherlin, Kyle D.,Ohta, Takehiro,Ogura, Takashi,Solomon, Edward I.,Cho, Jaeheung
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p. 12391 - 12399
(2016/12/14)
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- Chiral DHIP-Based Metal-Organic Frameworks for Enantioselective Recognition and Separation
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Two chiral porous 2,3-dihydroimidazo[1,2-a]pyridine (DHIP)-based metal-organic frameworks (MOFs) are assembled from an enantiopure dipyridyl-functionalized DHIP bridging ligand. The Zn-DHIP MOF shows a good enantioseparation performance toward aromatic sulfoxides, and the heterogeneous adsorbent can be readily recovered and reused without significant degradation of the separation performance.
- Zhang, Jie,Li, Zijian,Gong, Wei,Han, Xing,Liu, Yan,Cui, Yong
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supporting information
p. 7229 - 7232
(2016/08/09)
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- Importance of ground state stabilization in the oxovanadium(IV)-salophen mediated reactions of phenylsulfinylacetic acids by hydrogen peroxide – Non-linear Hammett correlation
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A systematic study on the oxidative decarboxylation of a series of phenylsulfinylacetic acids (PSAA) by hydrogen peroxide with four oxovanadium(IV)-salophen catalysts in 100% acetonitrile medium is presented. The hydroperoxovanadium(V)-salophen generated from the reaction mixture is identified as the bonafide active oxidizing species. Introduction of electron donating groups (EDG) in the oxovanadium(IV)-salophen catalyst and electron withdrawing groups (EWG) in PSAA enhances the reactivity, whereas EWG in the catalyst and EDG in PSAA have a retarding effect on the reaction. A Hammett correlation displays a non-linear downward curvature, which consists of two intersecting straight lines and the ρ value shifts from small positive to moderately high as the substituents change from EWG to EDG. The importance of the ground state stabilization of PSAA is inferred from a linear Yukawa–Tsuno plot. Based on the observed substituent effects and the spectral changes, a mechanism involving electrophilic attack of PSAA on the nucleophilic peroxo oxygen atom of the vanadium complex in the rate determining step followed by oxygen atom transfer is proposed.
- Subramaniam,Jeevi Esther Rathnakumari,Janet Sylvia Jaba Rose
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p. 496 - 503
(2016/07/21)
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- Bimetallic titanium complex catalyzed enantioselective oxidation of thioethers using aqueous H2O2 as a terminal oxidant
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A series of dimeric amino alcohol derived Schiff bases with various chiral amino alcohols and their corresponding bimetallic titanium complex were generated in situ. Thereafter with the in situ generated complexes, the asymmetric oxidation of prochiral aryl alkyl sulfides has been investigated using aqueous H2O2 as a terminal oxidant. During the study we found that the use of methanol or tert-butanol as an additive improved the catalytic activity in terms of both conversion and enantioselectivity. Moreover we observed a co-operative effect of the two reactive units of the bimetallic complex, which results in high reactivity as well as enantioselectivity compared to the corresponding monomeric complex. With this improved catalytic system several aryl alkyl sulfides and 1,3-dithianes were oxidised to the corresponding sulfoxides with good to high enantioselectivity (ee 78-99%) and conversion (70-99%). Unlike the monomer, oxidation of substrates like benzyl phenyl sulfide was achieved with high enantioselectivity as well as high yield.
- Bera, Prasanta Kumar,Gupta, Naveen,Abdi, Sayed H. R.,Khan, Noor-Ul H.,Kureshy, Rukhsana I.,Bajaj, Hari C.
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p. 47732 - 47739
(2015/06/16)
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- Electron-deficient heteroarenium salts: An organocatalytic tool for activation of hydrogen peroxide in oxidations
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A series of monosubstituted pyrimidinium and pyrazinium triflates and 3,5-disubstituted pyridinium triflates were prepared and tested as simple catalysts of oxidations with hydrogen peroxide, using sulfoxidation as a model reaction. Their catalytic efficiency strongly depends on the type of substituent and is remarkable for derivatives with an electron-withdrawing group, showing reactivity comparable to that of flavinium salts which are the prominent organocatalysts for oxygenations. Because of their high stability and good accessibility, 4-(trifluoromethyl)pyrimidinium and 3,5-dinitropyridinium triflates are the catalysts of choice and were shown to catalyze oxidation of aliphatic and aromatic sulfides to sulfoxides, giving quantitative conversions, high preparative yields and excellent chemoselectivity. The high efficiency of electron-poor heteroarenium salts is rationalized by their ability to readily form adducts with nucleophiles, as documented by low pKR+ values (pKR+ red > -0.5 V). Hydrogen peroxide adducts formed in situ during catalytic oxidation act as substrate oxidizing agents. The Gibbs free energies of oxygen transfer from these heterocyclic hydroperoxides to thioanisole, obtained by calculations at the B3LYP/6-311++g(d,p) level, showed that they are much stronger oxidizing agents than alkyl hydroperoxides and in some cases are almost comparable to derivatives of flavin hydroperoxide acting as oxidizing agents in monooxygenases.
- ?turala, Ji?í,Bohá?ová, Soňa,Chudoba, Josef,Metelková, Radka,Cibulka, Radek
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p. 2676 - 2699
(2015/03/18)
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- Selective H2O2 oxidation of organic sulfides to sulfoxides catalyzed by cobalt(III)-salen ion
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Abstract The catalytic activity of cobalt(III)-salen ion catalyzed selective H2O2 oxidation of organic sulfides to sulfoxides is examined using spectrophotometric technique. The catalytic reaction proceeds through Michaelis-Menten kinetics and the rate of the reaction is highly sensitive to the nature of the substituent present in the substrate as well as in the salen ligand. The product analyses show that the aryl methyl sulfides are selectively oxidized to the corresponding sulfoxides. Based on the spectral and kinetic studies two possible mechanisms have been proposed.
- Mary Imelda Jayaseeli,Ramdass, Arumugam,Rajagopal, Seenivasan
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supporting information
p. 59 - 66
(2015/08/11)
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- Tertiary amine mediated aerobic oxidation of sulfides into sulfoxides by visible-light photoredox catalysis on TiO2
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The selective oxidation of sulfides into sulfoxides receives much attention due to industrial and biological applications. However, the realization of this reaction with molecular oxygen at room temperature, which is of importance towards green and sustai
- Lang, Xianjun,Hao, Wei,Leow, Wan Ru,Li, Shuzhou,Zhao, Jincai,Chen, Xiaodong
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p. 5000 - 5005
(2015/07/27)
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- Synthesis and oxidation catalysis of a Ti-substituted phosphotungstate, and identification of the active oxygen species
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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.
- Takahashi, Eri,Kamata, Keigo,Kikukawa, Yuji,Sato, Sota,Suzuki, Kosuke,Yamaguchi, Kazuya,Mizuno, Noritaka
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p. 4778 - 4789
(2015/10/05)
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