- The remarkable effect of methanol on sulfide photooxidations. Evidence for its dual reactivity
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The addition of small amounts of methanol to photooxidation mixtures of sulfides dramatically enhances sulfone in preference to sulfoxide formation. High concentrations of methanol on the other hand have the opposite effect of promoting sulfoxide in prefe
- Clennan, Edward L.,Yang, Kang
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Read Online
- cis-Carbocuperation of acetylenic sulfoxides and corresponding applications in the regio- and stereoselective synthesis of polysubstituted vinyl sulfoxides
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cis-Carbocuperation reaction of monoorganocopper reagent with acetylenic sulfoxides, followed by electrophilic reaction with a variety of electrophiles, provided a regio- and stereoselective method to prepare the versatile polysubstituted vinyl sulfoxides
- Xu, Qing,Huang, Xian
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Read Online
- Synthesis and reactions of exo-camphorylsulfonyloxaziridine
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The first example of an exo-camphorylsulfonyloxaziridine 4a was prepared by m-CPBA oxidation of camphor imine 9. This surprising result is due to the conformation of the imine which apparently prevents attack of the peracid from the endo direction. Simila
- Davis, Franklin A.,Reddy, Rajarathnam E.,Kasu, Parimala V. N.,Portonovo, Padma S.,Carroll, Patrick J.
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Read Online
- Highly efficient and selective aqueous aerobic oxidation of sulfides to sulfoxides or sulfones catalyzed by tungstate-functionalized nanomaterial
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A Br?nsted acidic ionic solid comrising tungstate-functionaized polyorganosiloxane framework (PMO-IL-WO42?) efficiently catalysed aerobic oxidation of sulfides in aqueous medium. The catalyst can selectively produce sulfoxides or sulfones by running the reaction at room temperature or 50 °C, respectively. Because of the ionic liquid-based charged surface containing hydrophobic organic functional groups and hydrophilic sulfonic acid group, the synergestic hydrophobic/hydrophilic and redox effect of PMO-IL-WO42- as water-friendly interfacial nanocatalyst simplifies and enhances the activity and selectivity toward the target sulfoxides or sulfones in water. Moreover, the PMO-IL-WO42- nanocatalyst exhibited outstanding stability and activity and can be recycled eight reaction runs without any significant activity and selectivity loss.
- Luque, Rafael,Rajabi, Fatemeh,Vessally, Esmail,Voskressensky, Leonid
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- Development of a simple high-throughput assay for directed evolution of enantioselective sulfoxide reductases
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We report on the development of high-throughput fluorogenic assay that can streamline directed evolution of enantioselective sulfoxide reductases. As a model, methionine sulfoxide reductase A (MsrA) has been evolved to expand its limited substrate scope. The resulting mutant MsrA can resolve a range of new challenging racemic sulfoxides with high efficiency including the pharmaceutically relevant albendazole sulfoxide. The simplicity and the level of throughput make this method also suitable for the screening of metagenomic libraries in future for the discovery of new enzymes with similar reactivities.
- Tarallo, Vincenzo,Sudarshan, Kasireddy,Nosek, Vladimír,Mí?ek, Jirí
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supporting information
p. 5386 - 5388
(2020/06/04)
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- Selective Late-Stage Oxygenation of Sulfides with Ground-State Oxygen by Uranyl Photocatalysis
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Oxygenation is a fundamental transformation in synthesis. Herein, we describe the selective late-stage oxygenation of sulfur-containing complex molecules with ground-state oxygen under ambient conditions. The high oxidation potential of the active uranyl cation (UO22+) enabled the efficient synthesis of sulfones. The ligand-to-metal charge transfer process (LMCT) from O 2p to U 5f within the O=U=O group, which generates a UV center and an oxygen radical, is assumed to be affected by the solvent and additives, and can be tuned to promote selective sulfoxidation. This tunable strategy enabled the batch synthesis of 32 pharmaceuticals and analogues by late-stage oxygenation in an atom- and step-efficient manner.
- Li, Yiming,Rizvi, S. Aal-e-Ali,Hu, Deqing,Sun, Danwen,Gao, Anhui,Zhou, Yubo,Li, Jia,Jiang, Xuefeng
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supporting information
p. 13499 - 13506
(2019/08/21)
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- Sulfoxide and sulfone compounds, as well as selective synthesis method and application thereof
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The invention discloses a method for selectively synthesizing a sulfoxide compound shown as a formula (II) and a sulfone compound shown as a formula (III). In a reaction solvent, thioether (I) is usedas a reaction raw material and oxygen as an oxidation reagent, under the catalytic action of visible light and a photosensitive reagent; under the assistance of an additive, when a large-polarity proton-containing additive such as an acid and an alcohol or a solvent or an additive with excellent electron donating ability is used, a sulfoxide compound (II) is selectively generated; and when a small-polarity aprotic additive or a solvent is used, a sulfone compound (III) is selectively generated. The synthesis method has the advantages of easily available and cheap raw materials, simple reaction operation, mild reaction conditions, high yield and excellent functional group tolerance. According to the invention, synthesis and modification of some medicines are realized, and an efficient method for selectively constructing sulfoxide and sulfone compounds is provided for medicinal chemistry research.
- -
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Paragraph 0045-0048
(2019/12/02)
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- Ullmann-type: N-arylation of anilines with alkyl(aryl)sulfonium salts
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A palladium/copper-cocatalyzed Ullmann-type N-arylation of anilines using alkyl(aryl)sulfonium triflates as arylation reagents has been accomplished. The reaction enabled Caryl-S bond cleavage over Calkyl-S bond breakage of alkyl(aryl)sulfoniums by Pd(P(tBu)3)2/CuI and gave the corresponding N-arylated products in good to high yields. It was also significant that the reactions of aniline with asymmetric butyl(mesityl)(aryl)sulfonium triflates showed excellent selectivity, in which the aryl groups other than the bulky and electron-rich mesityl moieties were transformed.
- Tian, Ze-Yu,Zhang, Cheng-Pan
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supporting information
p. 11936 - 11939
(2019/10/11)
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- Chiral Br?nsted-Acid-Catalyzed Asymmetric Oxidation of Sulfenamide by Using H2O2: A Versatile Access to Sulfinamide and Sulfoxide with High Enantioselectivity
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Herein, we describe an example of catalytic asymmetric synthesis of sulfinamides. Aromatic sulfenamides were chosen as useful substrates, because of the indispensable N-H bond, which could form an efficient hydrogen bond with chiral phosphoric acid. Hsub
- Ma, Long-Jun,Chen, Shu-Sen,Li, Guang-Xun,Zhu, Jin,Wang, Qi-Wei,Tang, Zhuo
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p. 1525 - 1530
(2019/02/01)
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- Simple low cost porphyrinic photosensitizers for large scale chemoselective oxidation of sulfides to sulfoxides under green conditions: Targeted protonation of porphyrins
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Aerobic photooxidation of sulfides with the diacids of meso-tetra(phenyl)porphyrin, H2TPP (acid = CF3COOH, Cl2CHCOOH, HClO4 and H2SO4) under sunlight in acetonitrile gave the corresponding sulfoxides as nearly the exclusive product. The photocatalytic activity of the dications decreased as H4TPP(ClO4)2 ? H4TPP(Cl2CHCOO)2 ? H4TPP(CF3COO)2 > H4TPP(HSO4)2. Also, H4TPP(ClO4)2 and H4TPP(Cl2CHCOO)2 showed a remarkably increased oxidative stability in comparison with the free base porphyrin. The singlet oxygen quantum yield (φΔ) of the porphyrin diacids was found to be dependent on the acid used for the protonation of H2TPP. The solvent effect on the efficiency of the oxidation reaction was investigated using acetonitrile, 1,2-dichloroethane (DCE) and toluene. The higher conversions achieved in acetonitrile and DCE are in accord with the higher singlet oxygen lifetime in these solvents. Also, the lower fluorescence quantum yield of porphyrin dications in acetonitrile relative to that in DCE was used to explain the higher efficiency of the former. The porphyrin diacids can also accelerate the oxidation reaction through an acid catalysis mechanism. Also, cooxidation of methyl phenyl sulfide and diphenyl sulfide was conducted to provide insights into the nature of the active intermediates involved in the oxidation of sulfides to sulfoxides and partial overoxidation of the sulfoxides to sulfones. The results showed much higher reactivity of the persulfoxide intermediate compared to that of singlet oxygen. The catalytic system was successfully employed to the large scale preparation of sulfoxides from the corresponding sulfides under mild conditions.
- Mojarrad, Aida G.,Zakavi, Saeed
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p. 768 - 781
(2018/02/14)
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- Intermolecular Pummerer Coupling with Carbon Nucleophiles in Non-Electrophilic Media
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A new Pummerer-type C?C coupling protocol is introduced based on turbo-organomagnesium amides, which unlike traditional Pummerer reactions, does not require strong electrophilic activators, engages a broad range of C(sp3)-, C(sp2)-, and C(sp)-nucleophiles, and seamlessly integrates with C?H and C?X magnesiation. Given the central character of sulfur compounds in organic chemistry, this protocol allows access to unrelated carbonyls, olefins, organometallics, halides, and boronic esters through a single strategy.
- Colas, Kilian,Martín-Montero, Raúl,Mendoza, Abraham
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supporting information
p. 16042 - 16046
(2017/11/21)
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- Method for catalyzing asymmetric oxidation of sulfur ether
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The invention provides a method for asymmetrically oxidizing sulfur ether. The sulfur ether is subjected to asymmetric catalytic oxidation reaction by taking a chiral complex formed by a four-tooth nitrogen organic ligand and a metal scandium compound as a catalyst and taking hydrogen peroxide as an oxidizing agent to obtain a corresponding chiral sulfoxide compound, and the yield and the enantioselectivity are more than 90 percent. The reaction has the advantages of cleanness, mild reaction condition, high conversion rate and high enantioselectivity. The method has an industrial prospect.
- -
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Paragraph 0028; 0029; 0030; 0032
(2017/08/30)
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- One-Pot Sulfoxide Synthesis Exploiting a Sulfinyl-Dication Equivalent Generated from a DABSO/Trimethylsilyl Chloride Sequence
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A one-pot process for the synthesis of unsymmetrical sulfoxides using organometallic nucleophiles is described. Sulfur dioxide, delivered from the surrogate DABSO (DABCO-bis(sulfur dioxide)), acts as the initial electrophile and combines with the first organometallic reagent to generate a sulfinate intermediate. In situ conversion of the sulfinate to a sulfinate silyl ester, using TMS-Cl (trimethylsilyl chloride), generates a second electrophile, allowing addition of a second organometallic reagent. Organolithium or Grignard reagents can be employed, delivering sulfoxides in good to excellent yields.
- Lenstra, Danny C.,Vedovato, Vincent,Ferrer Flegeau, Emmanuel,Maydom, Jonathan,Willis, Michael C.
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supporting information
p. 2086 - 2089
(2016/06/01)
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- Symmetric diarylsulfoxides as asymmetric sulfinylating reagents for dialkylmagnesium compounds
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At -78 °C, primary dialkylmagnesium compounds reacted with diarylsulfoxides when 1.5 equiv of the dilithium salt of (S)-BINOL was added as a promotor. Alkyl aryl sulfoxides resulted in up to quantitative yield and with up to 97% ee. This demonstrates the feasibility of asymmetric sulfinylations by achiral sulfinylating agents (from the perspective of Alkyl2Mg) as well as the feasibility of asymmetric sulfoxide-magnesium exchanges (from the perspective of Ar2SO).
- Ruppenthal, Simon,Brückner, Reinhard
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p. 897 - 910
(2015/01/30)
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- Asymmetric oxidation catalysis by a porphyrin-inspired manganese complex: Highly enantioselective sulfoxidation with a wide substrate scope
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The first genuinely promising porphyrin-inspired manganese-catalyzed asymmetric sulfoxidation method using hydrogen peroxide has been successfully developed, allowing for rapidly oxidizing (0.5-1.0 h) a wide variety of sulfides in high yields with excellent enantioselectivities (up to >99% ee).
- Dai, Wen,Li, Jun,Chen, Bo,Li, Guosong,Lv, Ying,Wang, Lianyue,Gao, Shuang
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supporting information
p. 5658 - 5661
(2013/12/04)
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- Sulfenate substitution as a complement and alternative to sulfoxidation in the diastereoselective preparation of chiral β-substituted β-amino sulfoxides
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Building from a previous communication, the reaction of sulfenate anions with chiral N-Boc-protected β-substituted β-amino iodides was evaluated as a conceptually different synthetic approach to chiral β-substituted β-amino sulfoxides. Using arenesulfenat
- S?derman, Stefan C.,Schwan, Adrian L.
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p. 1638 - 1649
(2013/03/28)
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- Application of a novel 1,3-diol with a benzyl backbone as chiral ligand for asymmetric oxidation of sulfides to sulfoxides
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A chiral 1,3-diol with a benzyl backbone has been used for the asymmetric oxidation of sulfides to sulfoxides. Moderate to good yields and enantioselectivity (upto 87% ee) have been observed.
- Gogoi, Paramartha,Kotipalli, Trimurthulu,Indukuri, Kiran,Bondalapati, Somasekhar,Saha, Pipas,Saikia, Anil K.
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supporting information; experimental part
p. 2726 - 2729
(2012/07/17)
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- Efficient and highly selective aqueous oxidation of sulfides to sulfoxides at room temperature catalysed by supported iron oxide nanoparticles on SBA-15
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The present manuscript describes a simple, efficient and environmentally friendly room temperature aqueous catalytic approach to the selective preparation of sulfoxides from sulfides utilising low-loaded supported iron oxide nanoparticles and aqueous hydr
- Rajabi, Fatemeh,Naserian, Sareh,Primo, Ana,Luque, Rafael
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experimental part
p. 2060 - 2066
(2011/10/11)
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- Silver nitrate catalyzed oxidation of sulfides
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A variety of sulfides were converted into the corresponding sulfoxide derivatives with 70% tert-butyl hydroperoxide in water as the oxidant in the presence of catalytic quantity of silver nitrate. The method described has a wide range of application, does not involve cumbersome workup, exhibits chemoselectivity, and proceeds under mild reaction conditions, and the resulting products are obtained in good yields within a reasonable time. Georg Thieme Verlag Stuttgart New York.
- Das, Rima,Chakraborty, Debashis
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experimental part
p. 277 - 280
(2011/03/18)
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- Conjugate additions to alkylidene bis(sulfoxides)
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A general study on the conjugate addition of anionic nucleophiles to alkylidene bis(sulfoxides) is presented. Alkoxides gave high yielding and diastereoselective addition reactions, which could be influenced by solvents and the counteranion. Azides provided an interesting entry into sulfinyl-substituted triazoles. Organometallics, mainly copper reagents, proved also to be valuable nucleophiles, and complete inversion of the stereoselectivity was achieved in the addition reaction with the latter. Modelizations provide a rationale for the observed diastereoselectivity. Taking the Michael: Alkylidene bis(sulfoxides) are exquisite Michael acceptors toward a broad series of nucleophiles, and in most cases the reaction affords the adducts in high yields with complete diastereoselectivity.
- Brebion, Franck,Vincent, Guillaume,Chelli, Saloua,Kwasnieski, Ophelie,Najera, Francisco,Delouvrie, Benedicte,Marek, Ilan,Derat, Etienne,Goddard, Jean-Philippe,Malacria, Max,Fensterbank, Louis
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supporting information; experimental part
p. 1825 - 1833
(2012/02/01)
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- Practical and highly stereoselective method for the preparation of several chiral arylsulfinamides and arylsulfinates based on the spontaneous crystallization of diastereomerically pure N-benzyl-N-(1-phenylethyl)- arylsulfinamides
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A novel and simple process for the preparation of enantiomerically pure (SS)-benzenesulfinamide (SS)-3a, (SS)-p- toluenesulfinamide (SS)-3b, (SS)-p-chloro- benzenesulfinamide (SS)-3c and (SS)-p- fluorobenzenesulfinamide (SS)-3d has been developed. The treatment of arylsulfinyl chlorides with (R)-N-benzyl-1-phenylethanamine in the presence of excess triethylamine gave diastereomeric mixtures of N-benzyl-N-(1-phenylethyl)- arylsulfinamides 1, which underwent spontaneous crystallization to furnish diastereomerically pure (R,SS)-N-benzyl-N-(1-phenylethyl)- arylsulfinamides (R,SS)-1a-1d in 28%, 29%, 27% and 31% yields, respectively. The diastereomerically pure compounds (R,SS)-1 were then converted into four enantiopure (RS)-methyl arylsulfinates (RS)-2, and finally into four enantiopure (SS)- arylsulfinamides (SS)-3 in good yields.
- Zhu, Rui-Heng,Shi, Xiao-Xin
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p. 387 - 393
(2011/06/11)
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- Ti(iv)-amino triphenolate complexes as effective catalysts for sulfoxidation
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C 3-symmetric Ti (iv) amino triphenolate complexes efficiently catalyze, without previous activation and in excellent yields, the oxidation of sulfides at room temperature, using both CHP and the more environment friendly aqueous hydrogen peroxide as terminal oxidants, with catalyst loadings down to 0.01%. The Ti(iv) catalysts and the intermediate Ti(iv)-peroxo complexes have been characterized in solution by 1H NMR and ESI-MS techniques and via density functional studies.
- Mba, Miriam,Prins, Leonard J.,Zonta, Cristiano,Cametti, Massimo,Valkonen, Arto,Rissanen, Kari,Licini, Giulia
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experimental part
p. 7384 - 7392
(2010/09/17)
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- Cu(II)-catalyzed oxidation of sulfides
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A variety of sulfides and disulfides were converted into the corresponding sulfoxide derivatives with 70% t-BuOOH (water) as the oxidant in the presence of catalytic quantity of CuBr2. The method described does not involve cumbersome work-up, has wide range of applicabilities, exhibits chemoselectivity, and proceeds under mild reaction conditions, and the resulting products are obtained in good yields within reasonable time.
- Das, Rima,Chakraborty, Debashis
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scheme or table
p. 6255 - 6258
(2011/01/04)
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- C3-symmetric Ti(IV) triphenolate amino complexes as sulfoxidation catalysts with aqueous hydrogen peroxide
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(Chemical Equation Presented) The Ti(IV) complex 2c bearing a C 3-symmetric triphenolate amine ligand is an air and moisture tolerant complex that efficiently catalyzes sulfoxidation reactions at room temperature without previous activation (catalyst loading down to 0.01%, TONs up to 8000, TOFs up to 1700 h-1, quantitative yields). Reactions were performed with aqueous hydrogen peroxide as oxidant, which adds value to the methodology from the environmental viewpoint.
- Mba, Myriam,Prins, Leonard J.,Licini, Giulia
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- Efficient and selective sulfoxidation by hydrogen peroxide, using a recyclable flavin-[BMIm]PF6 catalytic system
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A new flavin catalyst 2 immobilized in an ionic liquid ([BMIm]PF 6) was used for the highly selective oxidation of sulfides to sulfoxides by hydrogen peroxide. The sulfoxides were obtained in good to high yields and high selectivity without any
- Linden, Auri A.,Johansson, Mikael,Hermanns, Nina,Baeckvall, Jan-E.
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p. 3849 - 3853
(2007/10/03)
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- Reagent-controlled asymmetric homologation of boronic esters by enantioenriched main-group chiral carbenoids
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Putative enantioenriched carbenoid species, (R)-1-chloro-2- phenylethylmagnesium chloride (9) and (S)-1-chloro-2-phenylethyllithium (26), generated in situ by sulfoxide ligand exchange from (-)-(Rs,R)-1- chloro-2-phenylethyl p-tolyl sulfoxide (8), effected the stereocontrolled homologation of boronic esters. sec-Alcohols derived from the product boronates by oxidation with basic hydrogen peroxide exhibited % ee closely approaching that of sulfoxide 8 in examples employing Li-carbenoid 26.
- Blakemore, Paul R.,Marsden, Stephen P.,Vater, Huw D.
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p. 773 - 776
(2007/10/03)
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- Novel synthesis of optically active 2-ethylhexanoic acid, 2-ethylhexanol, and 2-ethylhexylamine via the asymmetric favorskii rearrangement
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The asymmetric Favorskii rearrangement of optically active α-haloketones, which are easily prepared from chiral menthyl-4- toluenesulfoxide in several steps using primary or secondary amines, yields their corresponding secondary or tertiary chiral amides.
- Miura, Motofumi,Toriyama, Masaharu,Motohashi, Shigeyasu
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p. 259 - 264
(2007/10/03)
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- Alanine/chlorochromic acid/silica gel: An efficient and selective reagent for the oxidation of organic functional groups
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Alanine / chlorochromic acid / silica gel is a new and selective reagent for the efficient oxidation of sulfides, thiols, oximes, and alcohols. Oxidation of sulfides is solvent dependent. In chloroform at room temperature sulfoxides are formed as the major products, while in carbon tetrachloride or under solvent-free conditions solfones are produced in good-to-excellent yields.
- Salehi, Peyman,Khodaei, Mohammad Mehdi,Rostami, Amin
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p. 2235 - 2243
(2007/10/03)
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- Nucleophilic epoxidation of α′-hydroxy vinyl sulfoxides
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The nucleophilic epoxidation of a variety of α′-(1-hydroxyalkyl) vinyl sulfones and sulfoxides has been studied. The sulfones give rise to anti oxiranes with modest (E) or excellent (Z) selectivities and in good yields. The (E)-sulfoxides display low reactivity within a reinforcing/nonreinforcing scenario. The use of t-BuOOLi in Et2O allows for a highly syn-selective epoxidation-oxidation. The (Z)-sulfoxides display a remarkably high reactivity under these conditions. The reinforcing (S,Ss) diastereomers (3e-g) yield hydroxy sulfinyl oxiranes with high yields and selectivities. In contrast, the (R,Ss) diastereomers (4e-g) show diminished reactivities and a very substrate-dependent stereochemical outcome. The structure of these oxiranes has been secured by chemical correlations and an X-ray crystal structure.
- Fernandez de la Pradilla, Roberto,Fernandez, Jorge,Manzano, Pilar,Mendez, Paloma,Priego, Julian,Tortosa, Mariola,Viso, Alma,Martinez-Ripoll, Martin,Rodriguez, Ana
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p. 8166 - 8177
(2007/10/03)
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- Stereoselective addition to chiral p-toluene sulfinimines
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Diastereoselective addition of a number of Grignard reagents to chiral p-toluene sulfinimines 2b-2d under the mediation of copper salts afforded various protected α-branched amines. (C) 2000 Elsevier Science Ltd.
- Chan, Wing Hong,Lee, Albert W. M.,Xia, Ping Fang,Wong, Wai Yeung
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p. 5725 - 5728
(2007/10/03)
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- Bis(1-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane) peroxodisulfate: A mild and efficient oxidant for oxidation of thiols, sulfides and aromatic amines to the corresponding disulfides, sulfoxides and azo compounds
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Bis(1-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane) peroxodisulfate (BAABCPS) 1, readily prepared as orange solid from commercially available 1,4-diazabicyclo[2.2.2]octane (DABCO) and potassium peroxodisulfate converts thiols, sulfoxides and aromatic amines to the corresponding disulfides, sulfoxides and azo compounds respectively.
- Hajipour,Mohammadpoor Baltork,Kianfar
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p. 607 - 610
(2007/10/03)
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- 1-Benzyl-1-aza-4-azoniabicyclooctane periodate as new oxidant for oxidation of thiols and sulfides to the corresponding disulfides and sulfoxides under anhydrous conditions
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1-Benzyl-1-aza-4-azoniabicyclooctane periodate (BAABCOP) 1, readily prepared as an orange solid from commercially available DABCO (1,4-diazobicyclooctane) performs oxidation in anhydrous conditions. Under these conditions, thiols are selectively oxidised to disulfides. Sulfides are also oxidised to the corresponding sulfoxides under these conditions.
- Hajipour, A. R.,Mahboubghah, N.
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p. 1041 - 1043
(2007/10/03)
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- New procedures for the oxidation of sulfides to sulfoxides and sulfones
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New reagents for the oxidation of sulfides to the corresponding sulfoxides and sulfones are presented.
- Drabowicz, Jozef,Lyzwa, Piotr,Luczak, Jerzy,Mikolajczyk, Marian,Laur, Peter
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p. 425 - 426
(2007/10/03)
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- Asymmetric synthesis of chiral sulfoxides and sulfinimines by using N-sulfinylsultam
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Bornane-10,2-sultam 1 is stereoselectively converted by DMAP-assisted sulfinylation to diastereomerically pure (2R)-N-[(R)-p-tolylsulfinyl]-bornane-10,2-sultam 2 in 77% yield. The crystalline sulfinylating agent 2 reacts with a variety of nucleophiles to afford sulfoxides 3 and sulfinimines 5 in excellent yields and enantioselectivities.
- Oppolzer, Wolfgang,Froelich, Olivier,Wiaux-Zamar, Chantal,Bernardinelli, Gerald
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p. 2825 - 2828
(2007/10/03)
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- Improvement of optical purity of liquid sulfoxides via their mercury(ii) chloride complexes
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Crystallizatior or precipitation of the addition compounds of mercury(II) chloride with chiral sulfoxides of low enantiomeric excess have been found to increase substantially or fully their optical purity.
- Drabowicz, Jozef,Duozikiski, Bogdan,Mikolajczyk, Marian,Biscarini, Paolo
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p. 187 - 188
(2007/10/03)
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- Chemistry of Oxaziridines. 18. Synthesis and Enantioselective Oxidations of the oxaziridines
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The synthesis and enantioselective oxidations of oxaziridines 13 are reported.These reagents are prepared in two steps from the (camphorylsulfonyl)imine 4 by treatment of the corresponding azaenolate with electrophilic halogen sources followed by biphasic oxidation of the resulting dihalo imine 6-9 with m-CPBA/K2CO3.Of these oxaziridines the dichloro reagent 13b, available on a multigram scale, affords the highest enantioselectivities for the asymmetric oxidation of sulfides to sulfoxides (42-74 percent) and for the hydroxylation of enolates (often better than 95 percent ee).In general the molecular recognition is predicted and explained in terms of minimization of nonbonded steric interactions in the transition states.For the asymmetric oxidation of sulfides to sulfoxides, secondary electronic factors related to the polarity of the sulfide and oxaziridine also play a role.Definitive evidence for chelation of the metal enolate with the C-X bond in 13 is not found.The molecular recognition is interpreted in terms of the higher reactivity of the reagents and an active-site structure which is sterically complementary with the enolate.For the asymmetric hydroxylation of the Z- and E-enolates of propiophenone (16a), the Z-enolate exhibits much higher stereoselectivity than the E-enolate: >95 percent vs 22 percent ee.
- Davis, Franklin A.,Weismiller, Michael C.,Murphy, Christopher K.,Reddy, R. Thimma,Chen, Band-Chi
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p. 7274 - 7285
(2007/10/02)
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- Chemistry of oxaziridines. 17. N-(phenylsulfonyl)(3,3-dichlorocamphoryl)oxaziridine: A highly efficient reagent for the asymmetric oxidation of sulfides to sulfoxides
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The synthesis, structure, and enantioselective oxidations of a new chiral N-sulfonyloxaziridine 12c [3,3-dichloro-1,7,7-trimethyl-2'-(phenylsulfonyl)spiro[bicyclo[2.2.1]heptane-2, 3'-oxaziridine]] are reported. This oxidant, which exhibits remarkably high and predictable ee's for the enantioselective oxidation of prochiral sulfides to sulfoxides, is prepared in three steps from (+)- or (-)-camphor in 50% overall yield. Steric effects are primarily responsible for the molecular recognition and are predictable using a simple active-site model where the nonbonded interactions between the RL and RS groups of the sulfide (RL-S-RS) and the active-site surface are minimized in a planar transition-state structure. The fact that alkyl aryl sulfides give high ee's in nonpolar solvents suggests that there is also a stereoelectronic component to the molecular recognition. High ee's (>90%) are anticipated for those sulfides where the difference in size of the groups directly bonded to the sulfur atom is large, i.e., aryl, tert-butyl vs CH2R (R = H, alkyl, benzyl, etc). The X-ray structure and studies with the dihydro, difluoro, and dibromo oxaziridines 12a, 12b, and 12d reveal that the exceptional enantioselectivities displayed by 12c are a consequence of a molecular cleft or groove, defined by the oxaziridine chlorine atoms and phenylsulfonyl group, on the active-site surface.
- Davis, Franklin A.,Thimma Reddy,Han, Wei,Carroll, Patrick J.
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p. 1428 - 1437
(2007/10/02)
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- Remote Participation during Photooxidation at Sulfur. Eidence for Sulfurane Intermediates
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The photooxidations of geminally substituted γ-hydroxy sulfides results in formation of unusual oxidative elimination products.Detailed spectral data and the independent synthesis of a close analogue provide compelling evidence for the structures of these
- Clennan, E. L.,Yang, Kang
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p. 4477 - 4487
(2007/10/02)
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- Optically active sulfoxides by enantiospecific reactions of bromovinyl aryl sulfoxides with grignard reagents
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Optically active bromovinyl aryl sulfoxides were subjected to reactions with phenyl- or alkyl-magnesium compounds, with the production of optically active diaryl or aryl alkyl sulfoxides, with inversion of configuration. The enantiospecificity of the process was found to be 98-100%.
- Cardellicchio, Cosimo,Fiandanese, Vito,Naso, Francesco,Scilimati, Antonio
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p. 5121 - 5124
(2007/10/02)
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- Extremely Facile Ligand-Exchange and Disproportionation Reactions of Diaryl Sulfoxides, Selenoxides, and Triarylphosphine Oxides with Organolithium and Grignard Reagents
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Diaryl sulfoxides undergo unusually rapid ligand-exchange reaction upon treatment with organolithium reagents at -95 deg C.Optically pure phenyl p-tolyl sulfoxide (4b) reacted with organolithium reagents at the range from -20 to -95 deg C to give facile ligand-exchange and disproportionation products, i.e., diphenyl sulfoxide (7), recovered 4b, and di-p-tolyl sulfoxide (8) in a statistical ratio of 1:2:1 in quantitative yields, and the recovered 4b was completely racemized.This facile ligand exchange was observed in the similar reactions using only diaryl selenoxides and triarylphosphine oxides.The reactions of 18O-labeled phenyl p-tolyl sulfoxide (4c) with organolithium reagents gave products in a statistical ration without 18O scrambling, indicating that only the C-S bond cleavage took place under low temperature.It is suggested that the ligand exchange reactions occur by the nucleophilic attack by organolithium reagent at the sulfinyl sulfur atom, giving ?-sulfurane as an intermediate that collapses rapidly.These results suggest that the treatment of arylic sulfoxides, selenoxides, and phosphine oxides with strong bases should be effected with caution.
- Furukawa, Naomichi,Ogawa, Satoshi,Matsumura, Kazunori,Fujihara, Hisashi
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p. 6341 - 6348
(2007/10/02)
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- Preparation and Characterization of Optically Active Schiff Base-Oxovanadium(IV) and -Oxovanadium(V) Complexes and Catalytic Properties of These Complexes on Assymmetric Oxidation of Sulfides into Sulfoxides with Organic Hydroperoxides
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Oxovanadium(V) complexes, VVO (Schiff base)Y (Y=ClO4, Cl, NO3), with quadridentate Schiff base ligands derived from optically active 1,2-diamines and salicylaldehyde or its derivatives were prepared by oxidizing the corresponding VIV
- Nakajima, Kiyohiko,Kojima, Katsuhide,Kojima, Masaaki,Fujita, Junnosuke
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p. 2620 - 2630
(2007/10/02)
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- Microbial Oxidation of Alkyl Aryl Sulfides to the Corresponding Optically Active Sulfoxides
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Incubation of alkyl aryl sulfides with growing cells of Corynebacterium equi IFO 3730 afforded the corresponding sulfoxides and sulfones.The selectivity for the formation of sulfoxides over sulfones was higher with sulfides which have shorter alkyl chains.When methyl sulfides were used as substrates, formation of the corresponding sulfones was completely suppressed.Sulfoxides were revealed to have 87-100percent optically purities as to the (R) absolute configuration by HPLC analysis.The culture conditions seriously influenced the yield of oxidation products.High conversion of sulfides was attained when the reaction was carried out with grow ing cells in the logarithmic phase, in medium containing hexadecane as the carbon and energy source.
- Ohta, Hiromichi,Okamoto, Yasushi,Tsuchihashi, Gen-ichi
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p. 671 - 676
(2007/10/02)
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- ASYMMETRIC SYNTHESIS OF CHIRAL SULFOXIDES VIA MICROBIAL OXIDATION OF SULFIDES
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Incubation of alkyl aryl and allyl aryl sulfides with growing cells of Corynebacterium equi IFO 3730 gave the corresponding optically active sulfoxides with high enantiomeric excess.
- Ohta, Hiromichi,Okamoto, Yashushi,Tsuchihashi, Gen-ichi
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p. 205 - 208
(2007/10/02)
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- An Efficient Asymmetric Oxidation of Sulfides to Sulfoxides
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The Sharpless reagent for asymmetric epoxidation was modified by addition of 1 mol equiv of H2O to give a new homogenous reagent (Ti(O-i-Pr)4/diethyl tartrate/H2O/t-BuOOH = 1:2:1:1).This reagent cleanly oxidizes prochiral functionalized sulfides into optically active sulfoxides.The observed ee mainly ranged between 75 and 90percent for alkyl aryl sulfoxides and 50-71percent for dialkyl sulfoxides.A strong temperature dependence on ee was also observed in the asymmetric oxidation of methyl p-tolyl sulfoxide.
- Pitchen, P.,Dunach, E.,Deshmukh, M. N.,Kagan, H. B.
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p. 8188 - 8193
(2007/10/02)
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- Substitution at Tricoordinate Sulfur(IV). Rearrangement of Sulfinanilides to Anilino Sulfoxides
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Seven N-methyl-N-aryl-p-toluenesulfinamides (1, 3-Me2NC6H4; 2, 3-MeOC6H4; 3, 4-MeOC6H4; 4, 3-MeC6H4; 5, Ph; 6, 3-ClC6H4; 7, 3-FC6H4), N-(3-methoxyphenyl)-p-toluenesulfinamide (8), and two N-methyl-N-aryl-methanesulfinamides (9, 3-Me2NC6H4; 10, 3-MeOC6H4) were prepared from the corresponding sulfinyl chloride and the substituted aniline.Sulfinanilides 2 and 7 were treated with alkyllithiums in vain attempts to induce rearrangement to the diaryl sulfoxides via endocyclic nucleophilic attack by carbon 2 of the aniline ring on sulfur.Instead, the alkyllithium cleaved the S-N bond to yield the aniline and alkyl p-tolyl sulfoxide.Upon treatment with gaseous HCl in chloroform, the sulfinanilides rearranged as follows: 1 gave 4-(dimethylamino)-2-(methylamino)-4'-methyldiphenyl sulfoxide (92percent yield), 2 gave 2-methoxy-4-(methylamino)-4'-methyldiphenyl sulfoxide (26percent yield) and 4-methoxy-2-(methylamino)-4'-methyldiphenyl sulfoxide (70percent yield), 4 gave 2-methyl-4-(methylamino)-4'-methyldiphenyl sulfoxide (71percent yield), 9 gave methyl 4-(dimethylamino)-2-(methylamino)phenylsulfoxide (20percent yield), and 10 gave methyl 2-methoxy-4-(methylamino)phenyl sulfoxide (5percent yield).Sulfinanilides 3 and 5-8 did not rearrange.A tentative mechanism for the rearrangement is proposed.
- Andersen, Kenneth K.,Malver, Olaf
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p. 4803 - 4807
(2007/10/02)
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- Stereoselective Synthesis of Alcohols, II Stereochemistry of the Sigmatropic Rearrangement of 3-Substituted 2-Alkenyl Sulfoxides
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Rearrangement of the 3-E-substituted allyl sulfoxides 5 to the allyl alcohols 19 and 30 proceeds with low enantiomeric selectivity.In contrast, the 3-Z-substituted allyl sulfoxide 7b rearranged uniformly via the endo-transition state 26.
- Goldmann, Siegfried,Hoffmann, Reinhard W.,Maak, Norbert,Geueke, Karl-Josef
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p. 831 - 844
(2007/10/02)
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