- Visible-light-activated selective synthesis of sulfoxides via thiol-ene/oxidation reaction cascade
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A convenient, highly selective and metal-free synthesis of sulfoxides from alkenes and thiols using NHPI as an inexpensive and reusable organophotoredox catalyst is reported. The protocol involves radical thiol-ene/oxidation reaction cascade and utilizes visible light and air (O2) as inexpensive, readily available, non-toxic and eco-sustainable reagents to afford up to 96% yields of the product at room temperature.
- Singh, Manjula,Yadav, Arvind K.,Yadav, Lal Dhar S.,Singh
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p. 450 - 453
(2018/01/05)
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- Palladium/PC-Phos-Catalyzed Enantioselective Arylation of General Sulfenate Anions: Scope and Synthetic Applications
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Herein we reported an efficient palladium-catalyzed enantioselective arylation of both alkyl and aryl sulfenate anions to deliver various chiral sulfoxides in good yields (up to 98%) with excellent enantioselectivities (up to 99% ee) by the use of our developed chiral O,P-ligands (PC-Phos). PC-Phos are easily prepared in short steps from inexpensive commercially available starting materials. The single-crystal structure of the PC4/PdCl2 showed that a rarely observed 11-membered ring was formed via the O,P-coordination with the palladium(II) center. The salient features of this method include general substrate scope, ease of scale-up, applicable to the late-stage modification of bioactive compounds, and the synthesis of a marketed medicine Sulindac.
- Wang, Lei,Chen, Mingjie,Zhang, Peichao,Li, Wenbo,Zhang, Junliang
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p. 3467 - 3473
(2018/03/13)
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- Green Organocatalytic Oxidation of Sulfides to Sulfoxides and Sulfones
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A highly efficient synthetic methodology towards the selective synthesis of sulfoxides and sulfones is reported using a cheap and green organocatalytic method. Starting from sulfides and using 2,2,2-trifluoroacetophenone as the organocatalyst and H2O2 as the oxidant, the high-yielding preparation of sulfoxides or sulfones is described, being dependent on the reaction conditions.
- Voutyritsa, Errika,Triandafillidi, Ierasia,Kokotos, Christoforos G.
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p. 917 - 924
(2017/02/15)
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- Sulfoxidation of alkenes and alkynes with NFSI as a radical initiator and selective oxidant
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Sulfoxides are important functional molecules. We develop a short-route (one-pot) synthesis of this class of molecules by reacting thiols with alkenes or alkynes under mild and metal-free conditions. N-Fluorobenzenesulfonimide (NFSI) is used to play dual roles: as a radical initiator for a thiol-ene/-yne reaction to form sulfide adducts, and as efficient oxidant for conversion of the sulfides formed in situ to sulfoxides. Over-oxidation of the sulfoxides to sulfones is avoided in our approach.
- Zhang, Yuexia,Wong, Zeng Rong,Wu, Xingxing,Lauw, Sherman J. L.,Huang, Xuan,Webster, Richard D.,Chi, Yonggui Robin
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supporting information
p. 184 - 187
(2016/12/27)
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- Visible-light-induced selective synthesis of sulfoxides from alkenes and thiols using air as the oxidant
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A highly selective synthesis of sulfoxides from alkenes and thiols was established by visible-light photoredox catalysis at room temperature. This metal-free transformation protocol, which uses inexpensive Rose Bengal as the photocatalyst and air as the green oxidant, opens a new door toward the facile and practical construction of sulfoxides.
- Cui, Huanhuan,Wei, Wei,Yang, Daoshan,Zhang, Yulong,Zhao, Huijuan,Wang, Leilei,Wang, Hua
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supporting information
p. 3520 - 3524
(2017/08/15)
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- Acid-Catalyzed Oxidative Addition of Thiols to Olefins and Alkynes for a One-Pot Entry to Sulfoxides
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An oxidative variant of the thiol-ene reaction has been developed, achieving the direct addition of thiols to olefins to form sulfoxides. The reaction uses tert-butyl hydroperoxide as oxidant and methanesulfonic acid as catalyst. The latter is believed to catalyze the oxidation of the intermediate sulfide to the sulfoxide. No special precautions are necessary to exclude oxygen, yet the products are formed without oxidation at the β-position. Styrenes, acrylic acid derivatives, alkynes, and thiophenols gave the highest yields, while aliphatic olefins and thiols were less effective.
- Yue, Hui-Lan,Klussmann, Martin
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supporting information
p. 2505 - 2509
(2016/10/24)
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- Palladium-Catalyzed Arylation of Alkyl Sulfenate Anions
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A unique palladium-catalyzed arylation of alkyl sulfenate anions is introduced that affords aryl alkyl sulfoxides in high yields. Due to the base sensitivity of the starting sulfoxides, sulfenate anion intermediates, and alkyl aryl sulfoxide products, the use of a mild method to generate alkyl sulfenate anions was crucial to the success of this process. Thus, a fluoride triggered elimination strategy was employed with alkyl 2-(trimethylsilyl)ethyl sulfoxides to liberate the requisite alkyl sulfenate anion intermediates. In the presence of palladium catalysts with bulky monodentate phosphines (SPhos and Cy-CarPhos) and aryl bromides or chlorides, alkyl sulfenate anions were readily arylated. Moreover, the thermal fragmentation and the base promoted elimination of alkyl sulfoxides was overridden. The alkyl sulfenate anion arylation exhibited excellent chemoselectivity in the presence of functional groups, such as anilines and phenols, which are also known to undergo palladium catalyzed arylation reactions.
- Jia, Tiezheng,Zhang, Mengnan,Jiang, Hui,Wang, Carol Y.,Walsh, Patrick J.
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p. 13887 - 13893
(2016/01/15)
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- SnO 2 nanoparticles: Preparation and evaluation of their catalytic activity in the oxidation of aldehyde derivatives to their carboxylic acid and sulfides to sulfoxide analogs
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A variety of aromatic and aliphatic aldehydes were converted to the corresponding carboxylic acid derivatives with 30% H2O2 and tert-butyl hydroperoxide as the oxidant in the presence of a catalytic amount of SnO2 nanoparticles as a precursor. These nanoparticles were also used for the efficient catalytic oxidation of sulfides to sulfoxides using 30% H2O2. The present methodology offers several advantages such as applicability to a wide range of aldehydes/sulfides, convenient work-up, mild reaction conditions as well as good yields and reasonable time of the reactions. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.
- Dehbashi, Mohsen,Aliahmad, Mousa,Shafiee, Mohammad Reza Mohammad,Ghashang, Majid
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p. 864 - 872
(2013/08/23)
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- Reaction of singlet oxygen with some benzylic sulfides
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Product distribution, total quenching rate (kT), and rate of chemical reaction (kr) with singlet oxygen have been determined for some alkyl, benzyl, α-methylbenzyl, and cumyl sulfides. Their contributions depend on the steric hindering around the sulfur atom. In protic solvents, the sulfoxide is the main product via a hydrogen-bonded persulfoxide. In apolar solvents, intramolecular α-H abstraction leads to oxidative C-S bond cleavage, with varying efficiency. The behavior of sulfides is compared to that of alkenes and amines.
- Bonesi, Sergio M.,Fagnoni, Maurizio,Monti, Sandra,Albini, Angelo
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p. 10716 - 10723
(2007/10/03)
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- Selective oxidation of sulfides to sulfoxides using 30% hydrogen peroxide catalyzed with a recoverable silica-based tungstate interphase catalyst
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(Chemical Equation Presented) Various types of aromatic and aliphatic sulfides are selectively oxidized to sulfoxides and sulfones in good to excellent yields using 30% H2O2 in the presence of catalytic amounts of a novel recoverable silica-based tungstate interphase catalyst at room temperature. The catalyst can be recovered and reused for at least eight reaction cycles under the described reaction conditions without considerable loss of reactivity.
- Karimi, Babak,Ghoreishi-Nezhad, Maryam,Clark, James H.
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p. 625 - 628
(2007/10/03)
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- Catalytic Conversion of Sulfides to Sulfoxides by the [PZnMo 2W9O39]5- Polyoxometalate
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Keggin type polyoxometalates can be used as catalysts for the activation of 30% aqueous hydrogen peroxide for the selective transformation of various organic substrates. In this paper, results are presented for the oxidation of sulfides to sulfoxides in high to excellent yields using 30% aqueous H 2O2 as oxidant and [PZnMo2W9O 39]5- as catalyst in acetonitrile.
- Yadollahi, Bahram
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p. 1066 - 1067
(2007/10/03)
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- Mechanistic organic chemistry in a microreactor. Zeolite-controlled photooxidations of organic sulfides
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The intrazeolite and solution photooxygenations of a series of sulfides have been compared. The unusual zeolite environment enhances the rates of reaction, it suppresses the Pummerer rearrangements, and it has a dramatic effect on the sulfoxide/sulfone ratio. A detailed kinetic study utilizing trapping experiments and intramolecular competition provides evidence for cation complexation to a persulfoxide intermediate as the underlying phenomenon for the unique intrazeolite behavior. For example, the enhanced rate of reaction is traced to the cation stabilization of the persulfoxide toward unproductive decomposition to substrate and triplet oxygen.
- Clennan, Edward L.,Zhou, Wenhui,Chan, Jacqueline
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p. 9368 - 9378
(2007/10/03)
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- Oxidation by manganese dioxide (MnO2) catalysed with H2SO4/silica gel efficient solvent-free oxidation of thioethers to their corresponding sulfoxides
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H2SO4 mixed with silica gel (1:2) by weight produces a white powder which is an effective catalyst for the oxidation of thioethers to their corresponding sulfoxide by MnO2 under solvent-free conditions.
- Firouzabadi,Abbasi
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p. 1485 - 1491
(2007/10/03)
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- Bi(NO3)3.5H2O: A convenient reagent for selective oxidation of sulfides to sulfoxides
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Bi(NO3)3.5H2O, a cheaply available, crystalline solid has been found to readily effect selective oxidation of a variety of sulfides to surfoxides in acetic acid medium at room temperature in fair to good yields.
- Mashraqui, Sabir H.,Mudaliar, Chandrasekar D.,Karnik, Madhavi A.
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p. 939 - 943
(2007/10/03)
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- Oxidation of Aromatic Sulfides Photosensitized by TiO2 in CH3CN in the Presence of Ag2SO4. The Role of TiO2 in the Chemistry of Sulfide Radical Cations
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A product study of the photooxidation of the aromatic sulfides 1 - 5 sensitized by TiO2 in MeCN, in the presence of Ag2SO4, has been carried out. With benzyl phenyl sulfide (1), 4-methoxybenzyl phenyl sulfide (2), and phenethyl phenyl sulfide (4), the photooxidation led mainly to aldehydic products, benzaldehyde, 4-methoxybenzaldehyde, and phenylacetaldehyde, respectively. With benzyl 4-methoxyphenyl sulfide (3), the major product was the corresponding sulfoxide. Diphenyl sulfoxide was the only product observed in the oxidation of diphenyl sulfide (5). These results suggest α-C-H deprotonation as the major reaction path for the radical cations of 1, 2, and 4, and an active role in this respect of the oxygenated basic sites present on the TiO2 surface is envisaged. An interaction of these oxygenated centers with the sulfur atom of the adsorbed radical cation is also suggested to explain the remarkable finding that substantial amounts of sulfoxide are observed with 3 and 5, in spite of the fact that the photooxidations were carried under nitrogen. Different than with the sulfides, the photooxidation of 4-methoxybenzyl phenyl sulfoxide leads exclusively to products of C - S bond cleavage, which is attributed to the much greater stability of sulfinyl than thiyl radicals.
- Baciocchi, Enrico,Del Giacco, Tiziana,Ferrero, Marina I.,Rol, Cesare,Sebastiani, Giovanni V.
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p. 4015 - 4017
(2007/10/03)
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- Photolysis of Alkyl Aryl Sulfoxides: α-Cleavage, Hydrogen Abstraction, and Racemization
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The photochemistry of a series of alkyl aryl sulfoxides is described. The initial event of the photolysis process is homolytic cleavage to form sulfinyl/alkyl radical pairs. The radical pair partitions between recombination to starting material, formation of sulfenic esters, disproportionation to an olefin and benzenesulfenic acid, and formation of typical radical escape products. The quantum yield for conversion depends on the structure or the reactivity of the alkyl radical, with the sequence benzyl > tertiary alkyl > secondary alkyl > primary alkyl > (di)aryl. The high racemization efficiency of some aryl primary-alkyl sulfoxides suggests that another nonradical pathway for the photoracemization process may exist. Product analysis does not support any hydrogen abstraction pathways.
- Guo, Yushen,Jenks, William S.
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p. 857 - 864
(2007/10/03)
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- Sulfoxides from thioethers and MnO2-HCl
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Treatment of thioethers with manganese(IV)oxide-35% aqueous hydrogen chloride in methanol gives sulfoxides in high yields; sulfones are not produced.
- Fabretti,Ghelfi,Grandi,Pagnoni
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p. 2393 - 2398
(2007/10/02)
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- Oxidation of thioethers by manganese(IV) oxide-trimethylchlorosilane
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Thioethers are transformed by manganese(IV) oxide-trimethylchlorosilane in CH3OH in high yields to sulphoxides, exclusively.
- Bellesia,Ghelfi,Pagnoni,Pinetti
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p. 1759 - 1769
(2007/10/02)
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- A General Procedure for the Selective Oxidation of Sulfides to Sulfoxides by Nitric Acid: Tetrabromoaurate(III) Catalyst in a Biphasic System
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Tetrabromoaurate(III) is an efficient catalyst for the oxidation of sulfides to sulfoxides by nitric acid in a biphasic system (nitromethane/water).The system is selective and can be applied to the oxidation of any type of dialkyl and alkyl aryl sulfide and also of diaryl sulfides activated by electron-releasing substituents.The nature of the active species has been investigated in relation to the mechanistic aspects.
- Gasparrini, Francesco,Giovannoli, Mario,Misiti, Domenico,Natile, Giovanni,Palmieri, Gianni
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p. 1323 - 1328
(2007/10/02)
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- SYNTHESIS OF SULFOXIDES BY PHASE TRANSFER CATALYZED OXIDATION OF SULFIDES BY CERIUM (IV) AMMONIUM NITRATE
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Diaryl, dialkyl and alkyl aryl sulfides are oxidized by cerium(IV) ammonium nitrate in H2O/CH2Cl2, in the presence of tetra-n-butylammonium bromide, at room temperature, to give sulfoxides in yields ranging between 90 and 100percent.
- Baciocchi, Enrico,Piermattei, Alessandro,Ruzziconi, Renzo
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p. 2167 - 2172
(2007/10/02)
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- GOLD(III) CATALYZED OXIDATION OF SULFIDES TO SULFOXIDES BY NITRIC ACID UNDER PHASE-TRANSFER CONDITIONS: A NEW SYNTHESIS OF SULFOXIDES
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Gold(III) halides catalyze the oxidation of sulfides to sulfoxides in a phase-transfer process.The organic sulfides, dissolved in nitromethane, are treated with (Bu4N(1+)*AuCl4(1-)) in catalytic amount and aqueous nitric acid wich acts as an oxidant.The oxidation of the thio-group is selective and can be carried out also in the presence of other oxidizable groups, such as vinyl, tertiary amino, hydroxy, diol etc, which are left unchanged.Moreover in the case of asymmetric disulfides the reaction is regiospecific leading to the fomation of a single monosulfoxide.
- Gasparrini, F.,Giovannoli, M.,Misiti, D.,Natile, G.,Palmieri, G.
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p. 3181 - 3184
(2007/10/02)
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