- Chemoselective Method for the Preparation of Phenyl Sulfoxides by the Oxidation of Phenyl Sulfides with 2-Hydroperoxy-2-methoxypropane
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Phenyl sulfoxides are easily prepared by the chemoselective oxidation of the corresponding sulfides with molecular equivalents of 2-hydroperoxy-2-methoxypropane.This reagent is generated from 2,3-dimethyl-2-butene by ozonization in methanol.
- Leriverend, Pierre,Leriverend, Marie-Louise
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- Iodic acid (HIO3) in combination with tetraethylammonium bromide as a catalyst for selective and accelerated sulfoxidation
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The article describes the use of iodic acid in combination with catalytic amounts of tetraethylammonium bromide (TEAB) as a mild and alternative reagent system for oxidation of sulfides to sulfoxides. The salient features of the developed system are room-
- Salgaonkar, Paresh D.,Shukla, Vidyanand G.,Akamanchi
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- Selective oxidation of sulfides to sulfoxides using IBX-esters
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IBX-esters (esters of 2-iodoxybenzoic acid) are convenient hypervalent iodine reagents for the clean and selective oxidation of organic sulfides to sulfoxides. This reaction proceeds without over-oxidation to sulfones and is compatible with the presence of the hydroxy group, double bond, phenol ether, benzylic carbon, and various substituted phenyl rings in the molecule of the substrate.
- Koposov, Alexey Y.,Zhdankin, Viktor V.
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- Chiral Ligands in Hypervalent Iodine Compounds: Synthesis and Structures of Binaphthyl-Based λ3-Iodanes
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Several novel binaphthyl-based chiral hypervalent iodine(III) reagents have been prepared and structurally analysed. Various asymmetric oxidative reactions were applied to evaluate the reactivities and stereoselectivities of those reagents. Moderate to excellent yields were observed; however, very low stereoselectivities were obtained. NMR experiments indicated that these reagents are very easily hydrolysed in either chloroform or DMSO solvents leading to the limited stereoselectivities. It is concluded that the use of chiral ligands is an unsuccessful way to prepare efficient stereoselective iodine(III) reagents.
- Zhang, Huaiyuan,Cormanich, Rodrigo A.,Wirth, Thomas
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supporting information
(2021/12/22)
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- COMPOSITES, METHODS AND USES THEREOF
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The present invention relates, in general terms, to methods of catalysing a reaction, including the steps of contacting a chemical entity comprising a sulphide moiety with a composite and an oxidant. The composite acts as a heterogeneous catalyst to oxidise the sulphide moiety. The present invention also relates to composites, methods of synthesising the composites and its use as a catalyst thereof.
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Page/Page column 28
(2021/06/04)
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- Polyoxometalate-Based Organic-Inorganic Hybrids as Heterogeneous Catalysts for Cycloaddition of CO2with Epoxides and Oxidative Desulfurization Reactions
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Self-assembly of polyoxometalates, transition metal salts, and 2,6-bis(2′-pyridyl)-4-hydroxypyridine (LOH) obtained four organic-inorganic hybrids [Co2.5(LOH)(LO)2(H2O)2(PW12O39)]·3CH3CN·2OH (1), [Zn1.5(LOH)3]·(PMo12O40)·CH3OH·2H2O (2), [Cd1.5(LOH)3]·(PW12O40)·2CH3OH·1.5H2O (3), and [Mn(LOH)2]·(PW12O40)·2CH3CN·H3O (4). Hybrid 1 exhibits an extended chain, which could be further connected into a 3D supramolecular architecture by H-bonds. Hybrids 2-4 feature monomolecular structures, which are further bridged via H-bonds to yield charming 3D supramolecular structures. Noteworthy, 1 and 2 can be employed as recyclable and highly efficient heterogeneous catalysts. The activated 1 displays a high catalytic activity for the cycloaddition reaction of CO2 and epoxides. Hybrid 2 exhibits an excellent catalytic performance for the oxidative desulfurization reaction.
- Zhao, Yu-Qing,Liu, Ying-Ying,Ma, Jian-Fang
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p. 1019 - 1027
(2021/01/13)
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- Assembly of polyoxometalate-thiacalix[4]arene-based inorganic-organic hybrids as efficient catalytic oxidation desulfurization catalysts
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Self-assembly of polyoxometalates, Ni(ii)/Ag(i) cations and tetra-[5-(mercapto)-1-methyltetrazole]-thiacalix[4]arene (L) yielded three inorganic-organic hybrids, namely, [Ni3L2(CH3OH)6(H2O)4][PMo12O40]2·3CH3OH·2H2O (1), [Ni3L2(CH3OH)6(H2O)4][PW12O40]2·3CH3OH·2H2O (2) and [Ag3L(PMo12O40)] (3). In hybrids (1) and (2), Ni(ii) cations are linked by L ligands to produce layered frameworks, and H bonds among the [PMo12O40]3?/[PW12O40]3?anions and L ligands lengthen the structures to form 3D supramolecular architectures. Hybrid (3) exhibits a 3D architecture, of which Ag(i) cations not only coordinated with the N and O atoms of L ligands and [PMo12O40]3?anions simultaneously, but also connected each other by Ag-Ag interactions. It is worth mentioning that1and3as recyclable catalysts show excellent heterogeneous catalytic activity in oxidation desulfurization reactions.
- Li, Jie,Du, Peng,Liu, Ying-Ying,Ma, Jian-Fang
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supporting information
p. 1349 - 1356
(2021/02/09)
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- Selective and mild sulfoxidation of 2-sulfylbenzothiazole using hydroperoxides derived from cyclohexanone in the absence of catalyst
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Alkyl hydroperoxides derived from cyclohexanone are attractive oxidants because they are easily available, more reactive than TBHP but much less acidic than m-CPBA. Wherein 1,1′-peroxybis(1-hydroperoxycyclohexane) (C) can be generated by the current simply method and displays the excellent reactivity and selectivity based on oxidative reactions of various benzothiazolyl sulfides substituted by different function groups. The research found that the reactions can be performed in the absence of catalyst and under very mild conditions optimized. Yields of sulfoxides is higher than 90%, no or a little reaction happened at the proximal double bond、 N and S atoms in the benzothiazolyl moiety. Phenyl sulfide as the substrates was also examined for the reaction scope test. The results show that they were uniquely and completely oxidized to sulfoxides in 1 h. A mild, environmentally friendly, catalyst-free aryl sulfide sulfoxidation method has been developed.
- Shi, Wenjun,Yu, Chunmian,Zhou, Xinrui,Zhu, Shihao
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- Luminescent cis-Bis(bipyridyl)ruthenium(II) Complexes with 1,2-Azolylamidino Ligands: Photophysical, Electrochemical Studies, and Photocatalytic Oxidation of Thioethers
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New 1,2-azolylamidino complexes cis-[Ru(bipy)2(NH=C(R)az*-κ2N,N)](OTf)2 (R = Me, Ph; az? = pz, indz, dmpz) are synthesized via chloride abstraction after a subsequent base-catalyzed coupling of a nitrile with the previously coordinated 1,2-azole. The synt
- Cuéllar, Elena,Diez-Varga, Alberto,Torroba, Tomás,Domingo-Legarda, Pablo,Alemán, José,Cabrera, Silvia,Martín-Alvarez, Jose M.,Miguel, Daniel,Villafa?e, Fernando
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p. 7008 - 7022
(2021/05/29)
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- Organocatalytic sulfoxidation
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Treatment of a sulfide with a catalytic amount of a 1,3-diketone in the presence of silica sulfuric acid as a co-catalyst and hydrogen peroxide (50% aq) as the stoichiometric oxidant leads to the corresponding sulfoxide product. The reaction is effective for diaryl, aryl-alkyl and dialkyl sulfides and is tolerant of oxidisable and acid sensitive functional groups. Investigations have shown that the tris-peroxide 2, formed on reaction of pentane-2,4-dione with hydrogen peroxide under acidic reaction conditions, can oxidise two equivalents of sulfide using the exocyclic peroxide groups whereas the endocyclic peroxide remains intact. Calculations provide a mechanism consistent with experimental observations and suggest the reaction proceeds via an initial acid catalysed ring opening of a protonated tris-peroxide prior to oxygen transfer to a sulfur nucleophile.
- Davidson, Stuart C.,Gomes, Gabriel dos Passos,Kuhn, Leah R.,Alabugin, Igor V.,Kennedy, Alan R.,Tomkinson, Nicholas C.O.
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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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p. 156 - 161
(2021/01/14)
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- Chiral: N, N ′-dioxide-iron(iii)-catalyzed asymmetric sulfoxidation with hydrogen peroxide
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A highly enantioselective sulfoxidation of various sulfides has been achieved by a N,N′-dioxide-iron(iii) complex with 35% aq. H2O2 as the oxidant. The utility of the current method was demonstrated by asymmetric gram-scale synthesis of drug molecule (R)-modafinil. Moreover, a possible working mode was provided to elucidate the chiral induction.
- Dong, Shunxi,Feng, Lili,Feng, Xiaoming,Liu, Xiaohua,Wang, Fang
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supporting information
p. 3233 - 3236
(2020/03/23)
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- Two polyoxometalate-based inorganic-organic hybrids and one coordination polymer assembled with a functionalized calix[4]arene: Catalytic and electrochemical properties
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Self-assembly of 4-pyridyl-functionalized calix[4]arene ligand 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26,27,28-tetrakis[(4-pyridylmethyl)oxy]calix[4]arene (L), Ag(I)/Cd(II) cations and polyoxometalate obtained two inorganic-organic hybrids [Ag3(L)2][PMo12O40]·CH3CN·4H2O (1), [Ag3(L)2][PMo12O40]·2DMA·0.5EtOH (2) and one complex [Cd3(L)2Cl6]·4CH3CN·4H2O (3) (DMA = N,N-dimethylacetamide). Hybrids 1 and 2 have fascinating one-dimensional chains, which are linked by hydrogen bonds between the C atoms of L ligands and the O atoms of [PMo12O40]3? anions to generate supramolecular layers. 3 displays a thick layer containing trinuclear Cd(II) clusters. Noteworthy, hybrid 1 exhibits excellent heterogeneous catalytic activity for oxidative desulfurization reaction and obvious electrocatalytic activity for oxidize ascorbic acid and reduce NaBrO3. Complex 3 shows heterogeneous catalytic ability for Knoevenagel condensation reaction.
- Li, Zhuo,Liu, Ying-Ying,Xu, Guo-Hai,Ma, Jian-Fang
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- Efficient Catalytic Oxidative Desulfurization toward Thioether and Sulfur Mustard Stimulant by Polyoxomolybdate-Resorcin[4]arene-Based Metal-Organic Materials
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The design and synthesis of effective and recyclable oxidative desulfurization catalysts is of great importance in view of environmental protection and human health. Herein, a family of polyoxomolybdate-based inorganic-organic hybrid materials, namely, [Mn(TMR4A)(H2O)4][Mo6O19]·0.5CH3CH2OH·H2O (1), [Ni(TMR4A)(H2O)4][Mo6O19]·0.5CH3CH2OH·H2O (2), [Zn(TMR4A)(H2O)4][Mo6O19]·0.5CH3CH2OH·H2O (3), and [Co2(TMR4A)2(H2O)4(β-Mo8O26)]·CH3CN·12H2O (4), were assembled by the functionalized resorcin[4]arene ligand (TMR4A) with polyoxomolybdate and metal ions under solvothermal conditions. In isostructural 1-3, the [M(TMR4A)(H2O)4]2+ species (M = MnII, NiII, ZnII) and [Mo6O19]2- anions are held together via C-H···O hydrogen bonds to give a 3D supramolecular architecture. In 4, two [Co(TMR4A)(H2O)2]2+ cations were linked by one [β-Mo8O26]4- anion to produce an attractive molecular dimer. Remarkably, 1-4, as recyclable heterogeneous catalysts, exhibit efficient catalytic oxidation desulfurization activities toward thioethers. Particularly, 1, as a representative example, features selective catalytic oxidation for sulfur mustard simulant. Moreover, their electrochemical properties were also studied.
- Guo, Ting-Ting,Ma, Jian-Fang,Yang, Jin,Yu, Ming-Yue
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supporting information
(2020/04/02)
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- Alloxan-catalyzed biomimetic oxidations with hydrogen peroxide or molecular oxygen
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Inspired by biological flavin catalysis, the nonionic alloxan derivatives were applied as the biomimetic catalysts for various oxidations, catalyzing oxidations of sulfides and amines with hydrogen peroxide or molecular oxygen under mild conditions with high yields in a short time. The whole catalytic cycle has been verified to be a biomimetic approach through the formation of the alloxan hydroperoxide reactive intermediate. Additionally, encouraging asymmetric catalytic results have been obtained with an easily prepared chiral alloxan in a sulfoxidation reaction.
- Zhang, Shiqi,Li, Guangxun,Li, Ling,Deng, Xiongfei,Zhao, Gang,Cui, Xin,Tang, Zhuo
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p. 245 - 252
(2019/12/24)
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- Selective and solventless oxidation of organic sulfides and alcohols using new supported molybdenum (VI) complex in microwave and conventional methods
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A new dioxo-molybdenum (VI) complex supported on functionalized Merrifield resin (MR-Mo) has been synthesized and characterized by elemental, scanning electron mcroscopy, energy-dispersive X-ray analysis, TGA, Brunauer–Emmett–Teller method, powder-X-ray d
- Das, Siva Prasad,Boruah, Jeena Jyoti
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- Sulfoxide synthesis from sulfinate esters under Pummerer-like conditions
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A facile synthetic method for the preparation of allyl sulfoxides byS-allylation of sulfinate esters proceeds through sulfonium intermediates without [3,3]-sigmatropic rearrangement and further Pummerer-type reactions of the resulting allyl sulfoxides. On the basis of the plausible reaction mechanism involving sulfonium salt intermediates,S-alkynylation andS-arylation were also accomplished.
- Kobayashi, Akihiro,Matsuzawa, Tsubasa,Hosoya, Takamitsu,Yoshida, Suguru
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p. 5429 - 5432
(2020/06/04)
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- Highly stable polyoxometalate-resorcin[4]arene-based inorganic-organic complexes for catalytic oxidation desulfurization
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Self-assembly of a resorcin[4]arene-based ligand (TMR4A) with metal salts and H3PMo12O40·xH2O offers two isostructural complexes, namely, [Ni2Cl(TMR4A)2(CH3CN)2]·[PMo12O40]·4CH3CN (1) and [Co2Cl(TMR4A)2(CH3CN)2]·[PMo12O40]·4CH3CN (2). In both 1 and 2, one Cl? anion bridges two metal cations, and each metal cation is further chelated by four 2-mercaptopyridine N-oxide groups of one TMR4A, producing a [M2Cl(TMR4A)2]3+ dimer (M?=?Ni or Co). The negative [PMo12O40]3? as a counter-anion balances the positive charge. Markedly, 1 and 2 exhibit high stability in aqueous solutions with different pH values and in organic solvents. Remarkably, the efficient heterogeneous catalytic capability for oxidative desulfurization was studied by suing 1 and 2 as recycled catalysts. Moreover, the electrochemical behaviors of the two compounds were discussed as well.
- Yu, Ming-Yue,Yang, Jin,Xu, Xianxiu,Ma, Jian-Fang,Wang, Zhenxing
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- Polyoxometalate-Bridged Cu(I)- And Ag(I)-Thiacalix[4]arene Dimers for Heterogeneous Catalytic Oxidative Desulfurization and Azide-Alkyne "click" Reaction
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Two remarkable polyoxometalate-bridged Cu(I)- and Ag(I)-thiacalix[4]arene dimers, namely, [Cu4(SiW12O40)(L)2(DMF)2]·2EtOH·DMF (1-Cu) and [Ag4(PMo12O40)(L)2]·OH (1-Ag), were prepared by using a new thiacalix[4]arene, metal cation and polyoxometalate (L = tetra[2-(ethylthio)-1-methyl-1H-imidazole]-thiacalix[4]arene). In 1-Cu and 1-Ag, two thiacalix[4]arenes were linked together by one [SiW12O40]4- or [PMo12O40]3- anion via two metal cations to give a molecular dimer. Further, adjacent dimers were extended into a high-dimensional supramolecular architecture through hydrogen bonds. Markedly, these molecular dimers are exceedingly stable in organic solvents and then were employed as efficient catalysts for catalytic oxidation desulfurization as well as the azide-alkyne "click" reaction.
- Yu, Ming-Yue,Guo, Ting-Ting,Shi, Xiao-Chuan,Yang, Jin,Xu, Xianxiu,Ma, Jian-Fang,Yu, Zhen-Tao
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p. 11010 - 11019
(2019/08/26)
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- Copper Nanoparticles Immobilized on Nanocellulose: A Novel and Efficient Heterogeneous Catalyst for Controlled and Selective Oxidation of Sulfides and Alcohols
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In this work, we have described the versatility of low metal loading copper nanoparticles immobilized on nanocellulose for the controlled and selective oxidation of sulfides to sulfoxides and primary alcohols to aldehydes using green oxidant at room temperature. Aromatic, aliphatic and heterocyclic sulfides were oxidized to their corresponding sulfoxides with high yields without formation of over oxidized sulfones. Similarly, benzylic, allylic and aliphatic alcohols were selectively oxidized to aldehydes without traces of carboxylic acids in good to excellent yields.
- Dutta, Apurba,Chetia, Mitali,Ali, Abdul A.,Bordoloi, Ankur,Gehlot, Praveen S.,Kumar, Arvind,Sarma, Diganta
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p. 141 - 150
(2018/12/13)
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- A chitosan supported peroxidovanadium(V) complex: Synthesis, characterization and application as an eco-compatible heterogeneous catalyst for selective sulfoxidation in water
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Anchoring of peroxidovanadium(V) (pV) species to chitosan, a natural chelating polymer, afforded a new and structurally defined immobilized complex, VO(O2)2(NH2)-chitosan (ChpV) which was comprehensively characterized by e
- Saikia, Gangutri,Ahmed, Kabirun,Gogoi, Sandhya Rani,Sharma, Mitu,Talukdar, Hiya,Islam, Nashreen S.
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p. 192 - 205
(2019/01/03)
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- Water-soluble polymer anchored peroxotitanates as environmentally clean and recyclable catalysts for mild and selective oxidation of sulfides with H2O2 in water
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Anchoring of peroxotitanium (pTi) species to linear water-soluble acrylic acid based polymers, poly(sodium acrylate) (PA) and poly(sodium methacrylate) (PMA) led to the successful synthesis of a pair of new, water-tolerant and recyclable catalysts of the type [Ti2(O2)2O2(OH)2]4-—L (L = PA or PMA), highly effective in chemoselective sulfoxidation of organic sulfides with 30% H2O2 in aqueous medium at ambient temperature. The catalytic protocol is high yielding (TOF up to 11,280 h?1), operationally simple as well as environmentally clean and safe, being free from halide, or any other toxic auxiliaries. The catalysts are sufficiently stable to afford easy recyclability for at least 10 consecutive reaction cycles of sulfoxidation with consistent activity selectivity profile. Oxidation of dibenzothiophene (DBT) to respective high purity sulfoxide or sulfone could also be accomplished using the same catalysts by variation of reaction conditions.
- Ahmed, Kabirun,Saikia, Gangutri,Paul, Sivangi,Baruah, Satyajit Dey,Talukdar, Hiya,Sharma, Mitu,Islam, Nashreen S.
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- Polymer immobilized tantalum(v)-amino acid complexes as selective and recyclable heterogeneous catalysts for oxidation of olefins and sulfides with aqueous H2O2
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Polymer supported heterogeneous peroxotantalum(v) catalysts were prepared by anchoring Ta(v)-diperoxo species to chloromethylated poly(styrene-divinylbenzene) resin functionalized with amino acids asparagine (l-Asn) and arginine (l-Arg). The structurally well-defined catalysts, [Ta(O2)2(L)2]--MR, [L = asparagine (catalyst 1) or arginine (catalyst 2) and MR = Merrifield resin], were comprehensively characterized by elemental analysis (CHN, ICP-OES, energy dispersive X-ray spectroscopy), spectral studies (FT-IR, Raman, 13C NMR, diffuse reflectance UV-vis and XPS), SEM, XRD, Brunauer-Emmett-Teller (BET) and thermogravimetric analysis (TGA). The supported peroxotantalum (pTa) compounds displayed excellent catalytic performance in epoxidation of alkenes with 30% H2O2, under solvent free reaction conditions. Styrene was epoxidized with >99% selectivity with the highest TOF of 1040 h-1 obtained within 30 min reaction time, whereas the TOF for norbornene epoxidation was 2000 h-1 within 1 h with >95% epoxide selectivity. Furthermore, the immobilized catalysts facilitated chemoselective oxidation of a broad range of organic sulfides to the desired sulfoxides with H2O2 in methanol, under mild reaction conditions. The oxidations proceeded with a high H2O2 efficiency percentage and are amenable to ready scalability. The heterogeneous catalysts could be easily recovered and reused for several consecutive catalytic cycles with undiminished activity/selectivity profiles in all cases. The developed catalytic strategies are operationally simple and, being free from halogenated solvent or any other toxic auxiliaries, environmentally clean.
- Saikia, Gangutri,Ahmed, Kabirun,Rajkhowa, Chandrasee,Sharma, Mitu,Talukdar, Hiya,Islam, Nashreen S.
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p. 17251 - 17266
(2019/11/20)
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- Fe3O4?BNPs?SiO2-SO3H as a highly chemoselective heterogeneous magnetic nanocatalyst for the oxidation of sulfides to sulfoxides or sulfones
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To achieve green chemistry goals and also to reduce the cost of catalysts as well as to avoid producing toxic wastes and show the importance of separation and recycling of catalysts from the reaction medium, in this work, we describe the preparation and characterization of magnetic acidic boehmite nanoparticles as a heterogeneous catalyst, which is called Fe3O4?BNPs?SiO2-SO3H. This catalyst works efficiently in the selective oxidation of sulfides to sulfoxides or sulfones in the presence of H2O2 as a green oxidant. It can easily be separated from the reaction medium by using an external magnet and it was recycled 6 times without loss of magnetic catalytic properties.
- Ghanbari Kermanshahi, Mohammad,Bahrami, Kiumars
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p. 36103 - 36112
(2019/11/20)
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- Versatile catalysis of “natural extract”: oxidation of sulfides and alcohols and ipso-hydroxylation of arylboronic acids
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Abstract: In the present work, we have described the versatile applications of naturally available inexpensive citrous lemon juice as biocatalyst for controlled oxidation of sulfides and alcohols and ipso-hydroxylation of arylboronic acids using 30% H2O2 as a green oxidant. A series of structurally divergent sulfides and benzyl alcohols were oxidized to their corresponding sulfoxides and aldehydes, respectively, with good-to-excellent yields. Similarly, aryl and heteroaryl boronic acids were rapidly, often within minutes, transformed to their corresponding phenols at room temperature. Graphic abstract: [Figure not available: see fulltext.]
- Dutta, Apurba,Ali, Abdul Aziz,Sarma, Diganta
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p. 2379 - 2388
(2019/06/28)
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- Biocatalytical Asymmetric Sulfoxidation by Identifying Cytochrome P450 from Parvibaculum Lavamentivorans DS-1
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Cytochrome P450 monooxygenases (P450s) catalyzed asymmetric sulfoxidation represents a green route for the synthesis of valuable enantiopure sulfoxides, which are potentially interesting synthons in synthetic and pharmaceutical chemistry. Here the potential P450 and redox partner genes from Parvibaculum lavamentivorans DS-1 are screened and co-expressed in Escherichia coli host to construct twenty recombinant P450 strains. By testing the whole-cell biooxidation of thioanisole, P450PL2 (CYP278A4) and P450PL7 (CYP108G3) are identified with excellent S enantioselectivity while P450PL1 (CYP111B1) and P450PL9 (CYP153A26) exhibit the complementary R enantioselectivity. Asymmetric sulfoxidation of sulfides 1 a–1 m is further investigated using the recombinant E. coli strain P450PL2-2 based on the optimal conditions, producing the corresponding enantioenriched sulfoxides with up to 82 % isolated yield and 99 % ee.
- Wu, Kailin,Tang, Linchao,Cui, Haibo,Wan, Nanwei,Liu, Ziyan,Wang, Zhongqiang,Zhang, Shimin,Cui, Baodong,Han, Wenyong,Chen, Yongzheng
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p. 5410 - 5413
(2018/11/23)
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- A highly efficient reusable homogeneous copper catalyst for the selective aerobic oxygenation sulfides to sulfoxides
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Readily available copper showed efficient activity and great selectivity for the homogeneous catalysis of oxidation of sulfides to sulfoxides using molecular oxygen as the oxidant. The reaction proceeds under mild conditions in the presence of a catalytic amount of TEMPO. Importantly, the catalysts could be conveniently recovered and reused. And this methodology was proved to be applicable for the transformation of various aromatic and aliphatic sulfides into the corresponding sulfoxides with high conversion and high selectivity.
- Ren, Cheng,Fang, Runxing,Yu, Xiaochun,Wang, Shun
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supporting information
p. 982 - 986
(2018/02/13)
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- Synthesis of new oxido-vanadium complexes: Catalytic properties and cytotoxicity
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Reaction of 2,3-dihydroxy benzaldehyde with 2-({2-amino phenyl}diazenyl)phenol afforded the ligand 3-(2-(2-hydroxyphenyl)diazenyl)- 4-alkylphenyliminomethyl)benzene-1,2-diol. Reaction of H2L with VOSO4. 5H2O gave the oxido-vanadium(IV) complexes [(L)VO], which exhibited a quasi-reversible oxidative cyclic voltammetric response in a V(IV)/V(V) oxidative process. The complexes act as catalysts in the oxidation of organic thioethers and bromination of phenol. Their cytotoxic properties were examined for three cancer cell lines.
- Das, Uttam,Pattanayak, Poulami,Santra, Manas Kumar,Chattopadhyay, Surajit
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- Synthesis, characterization, spectral and catalytic activity of tetradentate (NNNO) azo-imine Schiff base copper(II) complexes
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The hexadentate ligand, 2,2′-bis(salicylideneamino)azobenzene, 1 has been synthesized from 2,2′-diaminoazobenzene and salicylaldehyde in refluxing diethyl ether. Reaction of ligand 1 with Cu(II) acetate and Cu(II) perchlorate separately in methanol afforded tetradentate (N,N,N,O) Cu(II) complexes, Cu(L) & [Cu(HL)]ClO4 respectively [where H2L represent the one imine moiety cleavage product of ligand 1 (H represents the dissociable amino and phenolic protons)]. These were characterized by microanalytical data and spectroscopic studies. In addition, the crystal structures of the ligand 1 and complexes Cu(L) & [Cu(HL)]ClO4 were determined by X-ray diffraction analysis. The diffraction analysis revealed that the ligand (H2L) binds Cu(II) centers in (N,N,N,O) tetra dentate fashion in distorted square planer geometry. In complex [Cu(HL)]ClO4 the apical position of copper center is weakly coordinated with one perchlorate ion. The dimeric structure of the molecule [Cu(HL)]ClO4 is stabilized through NH2···O hydrogen bonds. The fluorescence and redox property of ligand 1 and complexes Cu(L) & [Cu(HL)]ClO4 were studied. Preliminary DFT calculations were carried out using crystallographic coordinates to understand the electronic spectra and redox properties of the ligand and complexes. The complex Cu(L) shows very good catalytic activities towards oxidation of benzyl alcohol to benzaldeyhde (under solvent-free condition) and organic thioethers to sulfoxide and sulfones using H2O2 as the oxidant.
- Pratihar, Jahar Lal,Mandal, Paritosh,Brand?o, Paula,Mal, Dasarath,Felix, Vitor
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p. 221 - 228
(2018/05/22)
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- Thermolysis-Induced Two- or Multicomponent Tandem Reactions Involving Isocyanides and Sulfenic-Acid-Generating Sulfoxides: Access to Diverse Sulfur-Containing Functional Scaffolds
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Direct reaction of isocyanides with some sulfenic-acid-generating sulfoxides led to the effective formation of the corresponding thiocarbamic acid S-esters in good to high yields. A multicomponent reaction involving isocyanide, sulfoxide, and a suitable nucleophile has also been developed, providing ready access to a diverse range of sulfur-containing compounds, including isothioureas, carbonimidothioic acid esters, and carboximidothioic acid esters.
- Wu, Shengfeng,Lei, Xiaofang,Fan, Erkang,Sun, Zhihua
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supporting information
p. 522 - 525
(2018/02/10)
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- Fe3O4/PEG-SO3H as a heterogeneous and magnetically-recyclable nanocatalyst for the oxidation of sulfides to sulfones or sulfoxides
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We present below a sulfonated-polyethylene glycol-coated Fe3O4 nanocomposite (Fe3O4/PEG-SO3H) as a greatly effective and ecological nanocatalyst for the selective oxidation of sulfides to sulfoxides or sulfones with brilliant yields under solvent-free conditions by employing 30% hydrogen peroxide as the oxidant. A number of sulfides containing alcohol, ester, and aldehyde functional groups were fruitfully and selectively oxidized without altering the desired characteristics. The magnetic nanocatalyst (Fe3O4/PEG-SO3H) can be conveniently and swiftly retrieved through the utilization of an external magnetic tool and recycled for more than 10 reaction runs without significantly decreasing its catalytic behavior.
- Mirfakhraei, Saeideh,Hekmati, Malak,Eshbala, Fereshteh Hosseini,Veisi, Hojat
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p. 1757 - 1761
(2018/02/09)
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- Macromolecular metal complexes of NbV as recoverable catalysts for selective and eco-compatible oxidation of organic sulfides in water
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The activity of a pair of peroxoniobium(V) species immobilized on water soluble non-crosslinked polymers (WSP) formulated as, [Nb(O2)3(sulfonate)2]-PSS [PSS = poly(sodium styrene sulfonate)] (catalyst 1) and [Nb2(O2)6(carboxylate)2]-PA [PA = poly(sodium acrylate)] (catalyst 2) as efficient and recyclable catalysts for selective sulfoxidation of a variety of organic thioethers with 30% H2O2 in water is described. A new polymer anchored macrocomplex (catalyst 1) has been synthesized, from the reaction of sodium tetraperoxoniobate (NaNb) with 30% H2O2 and the macromolecular ligand poly(sodium styrene sulfonate) in an aqueous medium. The catalyst has been comprehensively characterized by spectral and other physicochemical techniques. Apart from being high-yielding and operationally simple, the additional important features which enhance the sustainability of the high yielding water-based oxidation protocol include chemoselectivity of the oxidation for sulfides and easy recyclability of the catalyst with consistent activity and selectivity for several cycles of oxidation.
- Gogoi, Sandhya Rani,Ahmed, Kabirun,Saikia, Gangutri,Islam, Nashreen S.
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p. 801 - 812
(2019/06/10)
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- Tungstate supported mesoporous silica SBA-15 with imidazolium framework as a hybrid nanocatalyst for selective oxidation of sulfides in the presence of hydrogen peroxide
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In this work, a new heterogeneous catalyst (SBA-15/Im/WO4 2?) was prepared, and then its performance in the oxidation of organic sulfides was studied (using 30% H2O2 as green oxidant under neutral reaction conditions). This organic–inorganic hybrid mesoporous material was characterized by various techniques, such as FT-IR, inductively coupled plasma, X-ray powder diffraction, high-resolution-transmission electron microscopy, N2 adsorption–desorption and thermogravimetric analysis. The catalyst was also applied to the selective oxidation of various sulfides. The hybrid catalyst was easily recovered, and was very stable and retained good activity for at least five successive runs without any additional activation. Moreover, there was no remarkable decrease in the activity and selectivity of the catalyst. The products could be easily isolated by just removing the solvent after filtering the catalyst. The yields of the catalytic productions through this catalyst were in the range from 75% to 97%.
- Sedrpoushan, Alireza,Hosseini-Eshbala, Fereshteh,Mohanazadeh, Farajollah,Heydari, Masoud
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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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- Schiff base Mn(III) and Co(II) complexes coated on Co nanoparticles: An efficient and recyclable magnetic nanocatalyst for H2O2 oxidation of sulfides to sulfoxides
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In this paper, an effective and selective heterogeneous catalyst was produced by immobilization of manganese and cobalt Schiff base-complexes on Co magnetite nanoparticles (MNP). The catalysts Co@SiO2[(EtO)3Si-L3]/M (M = Mn(iii) and Co(ii)) were synthesized using Co@SiO2 core-shell nanoparticles and amino-functionalized Co@SiO2. The Schiff base ligand Co@SiO2[(EtO)3Si-L3] was synthesized by reacting Co@SiO2 core-shell nanoparticles with 2-hydroxy 1-naphthaldehyde for the synthesis of Co@SiO2[(EtO)3Si-L3]/M. The catalysts were characterized by several techniques, such as FT-IR, TEM, XRD, TGA and VSM. The catalytic activities of the prepared catalysts were studied by oxidation of sulfides to the sulfoxides under different conditions. These catalysts can be easily recovered and reused in at least seven sequential cycles without considerable leaching and loss of reactivity.
- Saremi, Shokoufeh Ghahri,Keypour, Hassan,Noroozi, Mohammad,Veisi, Hojat
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p. 3889 - 3898
(2018/02/07)
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- One-pot synthesis of α-phenylsulfinyl ketones by reaction of phenyl benzenethiosulfinate with enolate anions, and synthesis of sulfoxides and sulfides by its reaction with Grignard reagents
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Phenyl benzenethiosulfinate reacts with enolate anions derived from ketones to give α-phenylsulfinyl ketones directly, together with minor amounts of α-phenylsulfanyl ketones. These are easily separated by forming the water-soluble sodium salts of the sulfinyl compounds. Grignard reagents also react with phenyl benzenethiosulfinate, to give mixtures of sulfoxides and sulfides.
- Fakhry, Jerome,Grayson, David H.
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p. 556 - 563
(2017/12/28)
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- Catalytic Activity of Crystallographically Characterized Organic–Inorganic Hybrid Containing 1,5-Di-amino-pentane Tetrachloro Manganate with Perovskite Type Structure
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Abstract: Layered 2D organic–inorganic hybrid perovskite (OIHS) of the diammonium series, 1,5 di-aminepentane tetrachloro mangenate ([NH3–(CH2)5–NH3] MnCl4) was prepared by slow evaporation and reducing temperature method and characterized by single crystal X-ray diffraction analysis. Its structure consists of organic cation, [NH3(CH2)5NH3]+2 extended in a zigzag fashion and inorganic anion, [MnCl6]?2 where Mn2+ is coordinated by six Cl? ion in octahedral fashion. The organic and inorganic segments are alternately stacked along c-axis where inorganic layer is extended through corner-shared octahedra sandwiched by the di-aminopentane molecules. The layers (organic and inorganic) were connected to each other through N–HCl hydrogen bonds and van-der Waals interaction to build cation–anion–cation cohesion. The hybrid crystal had orthorhombic non-centrosymetric system having I212121 space group with unit cell parameters a = 7.1742(3) ?, b = 7.3817(3) ?, c = 23.9650(10) ?, V = 1269.13 ?3 and Z = 4. The hybrid exhibited excellent catalytic activity towards sulphide and alkene oxidation using aqueous H2O2 as an oxidant. Graphical Abstract: OIHS of the diammonium series [NH3–(CH2)5–NH3] MnCl4; 1,5 di-aminepentane tetrachloro mangenate were prepared by slow evaporation and temperature decrease method, characterized by single crystal X-ray diffraction. This complex exhibits excellent catalytic activity towards sulphide oxidation and alkene oxidation using aqueous H2O2 as an oxidant. [Figure not available: see fulltext.].
- Mondal, Paramita,Abdel-Aal, Seham Kamal,Das, Debasis,Islam, Sk Manirul
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p. 2332 - 2339
(2017/08/22)
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- Access to N-cyanosulfoximines by transition metal-free iminations of sulfoxides
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A transition metal-free synthesis of N-cyanosulfoximines from sulfoxides using N-chlorosuccinimide (NCS) as oxidising agent and cyanamide as nucleophilic amine source is reported. The products are obtained in moderate to excellent yields. The protocol enables an easy access to N-cyanosulfoximines from readily available starting materials under inversion of configuration at a preexisting stereogenic center.
- Dannenberg,Fritze,Krauskopf,Bolm
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supporting information
p. 1086 - 1090
(2017/02/10)
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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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- Solvent, metal and halogen-free synthesis of sulfoxides by using a recoverable heterogeneous urea-hydrogen peroxide silica-based oxidative catalytic system
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An efficient and green protocol was used for the selective oxidation of sulfides to sulfoxides by using silica sulfuric acid (SSA) as a recoverable heterogeneous solid acid catalyst in the presence of urea-hydrogen peroxide (UHP) under toxic transition me
- Azizi, Mojtaba,Maleki, Ali,Hakimpoor, Farahman
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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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- Synthesis method of aryl sulfoxide compound
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The invention relates to a synthesis method of an aryl sulfoxide compound shown in the following formula (II). The synthesis method comprises the steps as follows: a compound shown in formula (I) is subjected to a catalytic oxidation reaction by using a c
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Paragraph 0103; 0104; 0105; 0106-0108; 0111; 0116; 0121K
(2017/07/20)
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- A route to benzylic arylsulfoxides from β-ketosulfoxides
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The K2CO3-mediated benzylation of β-ketosulfoxides 4 with 2.0?equiv of benzylic halides 5 affords benzylic arylsulfoxides 6 in moderate yields along with trace amounts of chalcones 7. The products 6 are assumed to form in situ intermediates of sulfenate anions from β-ketosulfoxides which are commonly involved in carbon–sulfur bond formation. A plausible mechanism has been proposed.
- Chang, Meng-Yang,Cheng, Yu-Chieh,Chan, Chieh-Kai
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p. 4068 - 4075
(2016/07/06)
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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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- Peroxomolybdate supported on water soluble polymers as efficient catalysts for green and selective sulfoxidation in aqueous medium
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Peroxomolybdenum(VI) species immobilized on linear water soluble polymers formulated as, [MoO(O2)2(sulfonate)]–PS [PS?=?poly(sodium vinyl sulfonate)] (PSMo) and[Mo2O2(O2)4(carboxylate)]–PA [PA?=?poly(sodium acrylate)](PAMo) served as efficient and recyclable catalysts for selective oxidation of organic sulfides to sulfoxide in water with 30% H2O2. The new polymer anchored complex, PSMo has been prepared by reacting H2MoO4 and 30% H2O2 with macromolecular ligand, poly(sodium vinyl sulfonate) and characterized by elemental analysis, spectral studies (FTIR, Raman, 13C NMR, 95Mo NMR, UV–vis), SEM, EDX and TGA-DTG analysis. The catalytic protocol effects clean and facile oxidation of a wide range of sulfides to afford pure sulfoxides with high TOF and excellent chemoselectivity at ambient temperature,with an easy work-up procedure. The catalysts can be regenerated in-situ and recycled at least up to ten consecutive reaction cycles without significant loss of activity and are amenable for ready scalability. The catalytic procedure thus provides an ecologically sustainable alternative as it involves water as solvent, H2O2 as green oxidant, a recyclable non-polluting catalyst, and is absolutely free from halide, organic co-solvent or co-catalyst. This is the first catalytic protocol for selective aqueous oxidation of sulfides using a catalytic system based on peroxometal species supported on water soluble polymers.
- Boruah, Jeena Jyoti,Ahmed, Kabirun,Das, Srewashi,Gogoi, Sandhya Rani,Saikia, Gangutri,Sharma, Mitu,Islam, Nashreen S.
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- Dirhodium(II)-Catalyzed Sulfide Oxygenations: Catalyst Removal by Coprecipitation with Sulfoxides
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The dirhodium(II) carboxylate complex Rh2(esp)2 (esp = α,α,α′,α′-tetramethyl-1,3-benzenedipropanoate) was shown to catalyze the sulfoxidation of organic sulfides using tert-butyl hydroperoxide as the oxidant. Due to the unique structure of Rh2(esp)2 and its stable Rh2(II,II) catalyst resting state, the rhodium catalyst is able to precipitate as a Rh2(esp)2-sulfoxide complex following the reaction which makes separation of the catalyst from the products very convenient. The precipitated Rh2(esp)2-sulfoxide complexes could be reused to catalyze sulfide oxygenation reactions without considerable loss of activity. Mechanistic studies suggest that the axial ligands fine-tune the redox potential of the dirhodium(II,II) compounds and determine the predominant catalyst species in the oxidation reaction.
- Zhao, Lili,Zhang, Hongyang,Wang, Yuanhua
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p. 129 - 136
(2016/01/15)
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- Oxidation of sulfides using recyclable pseudocyclic benziodoxole triflate
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A new pseudocyclic hypervalent iodine reagent, benziodoxole triflate (IBA-OTf, a complex of 2-iodosylbenzoic acid with trifluoromethanesulfonic acid), can be used as an efficient oxidant for selective oxidation of various organic sulfides to sulfoxides. This oxidation proceeds under mild condition to afford the corresponding sulfoxides in moderate to good yields without overoxidation. The reduced form of the hypervalent iodine reagent, 2-iodobenzoic acid, can be easily recovered from the reaction mixture in good yields by a simple acid-base liquid-liquid biphasic protocol. (Chemical Equation Presented).
- Yoshimura, Akira,Zhdankin, Viktor V.
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- Anion effect of 5-ethylisoalloxazinium salts on flavin-catalyzed oxidations with H2O2
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The anion effect of the 5-ethylisoalloxazinium salts on their catalytic activity was investigated for the oxidation of sulfide with aq H2O2in order to design more practical and safer flavinium salt catalysts that can replace the conventional perchlorate salt. The anions forming stronger conjugated acids were found to accelerate the catalytic sulfoxidation. The riboflavin-derived isoalloxazinium triflate salt was chosen as a readily accessible flavin with an efficient catalytic activity. In fact, the isoalloxazinium triflate 1b is an excellent organocatalyst for the chemoselective oxidations of a sulfide to a sulfoxide, Bayer–Villiger reaction of a cyclobutanone to a γ-butyrolactone, Dakin reaction of an arylaldehyde to a phenol, and oxidation of an aldehyde to a carboxylic acid using aq H2O2as a terminal oxidant under mild conditions.
- Iida, Hiroki,Ishikawa, Tatsuro,Nomura, Keisuke,Murahashi, Shun-Ichi
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supporting information
p. 4488 - 4491
(2016/09/14)
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- Efficient Metal-Free Aerobic Photooxidation of Sulfides to Sulfoxides Mediated by a Vitamin B2Derivative and Visible Light
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We have developed a metal-free process for the aerobic photooxygenation of sulfides to sulfoxides mediated by riboflavin tetraacetate or riboflavin (vitamin B2) photocatalysts and visible light (450 nm) in an acetonitrile-water (85:15 v/v) mixture. The optimised solvent system leads to both singlet-oxygen and electron-transfer pathways in photooxygenation, thus allowing oxidation of electron-poor and electron-rich thioanisoles, dialkyl sulfides and sterically hindered sulfides. Besides having a broad substrate scope, the method has very short reaction times and requires low catalyst loading (down to 0.1 mol%). These properties are due to the high photocatalyst stability and the extremely high quantum yields (1.3 for thioanisole oxygenation). Moreover, the method is chemoselective, producing only sulfoxides without overoxidation to sulfones. Taking into account the broad substrate scope, high selectivity and high efficiency, this method distinguishes itself from those previously reported. Other advantages include easy work-up of the reaction mixture, the availability and biodegradability of the photocatalysts and mild reaction conditions. We demonstrated, on a preparative scale, its practical application in the synthesis of the psychostimulant modafinil, in the selective oxidation of methionine derivatives, and in the detoxification of mustard gas. (Figure presented.).
- Nevesely, Tomá?,Svobodová, Eva,Chudoba, Josef,Sikorski, Marek,Cibulka, Radek
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p. 1654 - 1663
(2016/10/13)
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- Selective Synthesis of Sulfoxides through Oxidation of Sulfides with Sodium Hypochlorite Pentahydrate Crystals
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Oxidation of sulfides with sodium hypochlorite pentahydrate crystals (1.1 equiv) in an aqueous acetonitrile solution selectively produces the corresponding sulfoxides in high yields. This procedure is catalyst-free and environmentally benign.
- Okada, Tomohide,Matsumuro, Hiroaki,Kitagawa, Saori,Iwai, Toshiaki,Yamazaki, Kento,Kinoshita, Yukari,Kimura, Yoshikazu,Kirihara, Masayuki
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p. 2547 - 2552
(2015/11/16)
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- Efficient and selective hydrogen peroxide-mediated oxidation of sulfides in batch and segmented and continuous flow using a peroxometalate-based polymer immobilised ionic liquid phase catalyst
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The peroxometalate-based polymer immobilized ionic liquid phase catalyst [PO4{WO(O2)2}4]@PIILP has been prepared by anion exchange of ring opening metathesis-derived pyrrolidinium-decorated norbornene/cyclooctene copolymer and shown to be a remarkably efficient system for the selective oxidation of sulfides under mild conditions. A cartridge packed with a mixture of [PO4{WO(O2)2}4]@PIILP and silica operated as a segmented or continuous flow process and gave good conversions and high selectivity for either sulfoxide (92% in methanol at 96% conversion for a residence time of 4 min) or sulfone (96% in acetonitrile at 96% conversion for a residence time of 15 min). The immobilized catalyst remained active for 8 h under continuous flow operation with a stable activity/selectivity profile that allowed 6.5 g of reactant to be processed (TON = 46 428) while a single catalyst cartridge could be used for the consecutive oxidation of multiple substrates giving activity-selectivity profiles that matched those obtained with fresh catalyst.
- Doherty,Knight,Carroll,Ellison,Hobson,Stevens,Hardacre,Goodrich
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supporting information
p. 1559 - 1571
(2015/03/18)
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- Polyoxomolybdate-Calix[4]arene Hybrid: A Catalyst for Sulfoxidation Reactions with Hydrogen Peroxide
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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.
- Meninno, Sara,Parrella, Alessandro,Brancatelli, Giovanna,Geremia, Silvano,Gaeta, Carmine,Talotta, Carmen,Neri, Placido,Lattanzi, Alessandra
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supporting information
p. 5100 - 5103
(2015/11/03)
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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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