- Ceramic boron carbonitrides for unlocking organic halides with visible light
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Photochemistry provides a sustainable pathway for organic transformations by inducing radical intermediates from substrates through electron transfer process. However, progress is limited by heterogeneous photocatalysts that are required to be efficient, stable, and inexpensive for long-term operation with easy recyclability and product separation. Here, we report that boron carbonitride (BCN) ceramics are such a system and can reduce organic halides, including (het)aryl and alkyl halides, with visible light irradiation. Cross-coupling of halides to afford new C-H, C-C, and C-S bonds can proceed at ambient reaction conditions. Hydrogen, (het)aryl, and sulfonyl groups were introduced into the arenes and heteroarenes at the designed positions by means of mesolytic C-X (carbon-halogen) bond cleavage in the absence of any metal-based catalysts or ligands. BCN can be used not only for half reactions, like reduction reactions with a sacrificial agent, but also redox reactions through oxidative and reductive interfacial electron transfer. The BCN photocatalyst shows tolerance to different substituents and conserved activity after five recycles. The apparent metal-free system opens new opportunities for a wide range of organic catalysts using light energy and sustainable materials, which are metal-free, inexpensive and stable. This journal is
- Yuan, Tao,Zheng, Meifang,Antonietti, Markus,Wang, Xinchen
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p. 6323 - 6332
(2021/05/19)
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- Cu2O-catalyzed C–S coupling of quaternary ammonium salts and sodium alkane-/arene-sulfinates
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A new protocol for the synthesis of (enantioenriched) benzylic sulfones via the Cu2O-catalyzed C–S bond cross coupling of alkane-/arene-sulfinates and (enantioenriched) benzylic quaternary ammonium salts has been developed. The product benzylic sulfones were obtained in good to high yields (75–96%). Chiral arylmethyl sulfones with high enantiomeric excess (90–94% ee) were also synthesized in the presence of Cu2O and 1,1′-bis-(diphenylphosphino)ferrocene (dppf).
- Chen, Hongyi,Huang, Youming,Zeng, Qingle,Zheng, Wenting
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- Cyanide-Mediated Synthesis of Sulfones and Sulfonamides from Vinyl Sulfones
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We report a facile synthesis of sulfones, β-keto sulfones, and sulfonamides from vinyl sulfones via an addition-elimination sequence where in situ generation of nucleophilic sulfinate ion is mediated by cyanide. The use vinyl sulfones renders high selectivity for S -alkylation to produce sulfones in high yields. In the presence of N -bromosuccinimide, primary and secondary amines underwent sulfonamide formation. A preliminary mechanistic study showed the formation of acrylonitrile as an innocent byproduct, without interfering with the desired reaction pathway while generating a sulfinate nucleophile.
- Lee, Ji-Woong,Roy, Tamal
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p. 455 - 458
(2020/03/13)
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- Base-controlled divergent synthesis of vinyl sulfones from (benzylsulfonyl)benzenes and paraformaldehyde
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A tuneable metal-free protocol for the selective preparation of a-substituted vinyl sulfone and (E)-vinyl sulfone derivatives has been described. In this process, stable paraformaldehyde was used as the carbon source. The base played an important role in the selectivity control of transformations. More than 50 products were synthesized with excellent chemoselectivity and broad functional group tolerance.
- Xiao, Fuhong,Hu, Yangling,Huang, Huawen,Xu, Fen,Deng, Guo-Jun
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supporting information
p. 3527 - 3535
(2020/05/25)
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- Selective oxidation of sulfides to sulfoxides/sulfones by 30% hydrogen peroxide
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A selective and efficient procedure for the oxidation of various sulfides with sodium tungstate dihydrate with 30% hydrogen peroxide in the presence of trioctylmethylammonium dihydrogen phosphate, respectively, to the corresponding sulfoxides and sulfones is reported. The oxidation reaction is carried out at -5 to 0 °C in the presence of hydroxypropyl -β cyclodextrins for sulfoxides or at 50-60 °C for sulfones. The mild reaction conditions, easy workup, and good yields of the products are the major advantages of this method. Copyright Taylor and Francis Group, LLC 2012.
- He, Ying,Ma, Xiaoyun,Ji, Hai Feng,Zha, Xin Bing,Jiang, Hongliang,Lu, Ming
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experimental part
p. 822 - 830
(2012/08/07)
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- Highly atom-economic, catalyst- and solvent-free oxidation of sulfides into sulfones using 30% aqueous H2O2
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Highly atom-efficient oxidation of sulfides into sulfones under solvent- and catalyst-free reaction conditions using a 30% aqueous solution of H 2O2 at 75 °C is reported. A structurally diverse set of phenyl alkyl-, phenyl benzyl-, benzyl alkyl-, dialkyl-, heteroaryl alkyl- and cyclic sulfides were transformed into sulfones regardless of the aggregate state and electronic nature of the substituents. In spite of the heterogeneous reaction mixtures throughout the work, no difficulties with stirring and reaction progress were noted. In numerous cases, only 10 mol% excess of H 2O2 was used, thus contributing considerably to the high atom economy of the process. Some solid substrates required a variable excess of hydrogen peroxide; however, the reactions were performed strictly without organic solvents. The transformation was demonstrated to be amenable for scale-up with both liquid and solid sulfides. In addition, isolation and purification of the crude products can be simply done with only filtration and crystallization.
- Jereb, Marjan
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supporting information
p. 3047 - 3052,6
(2020/09/16)
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- Selective oxidation of sulfides to sulfoxides and sulfones at room temperature using H2O2 and a Mo(VI) salt as catalyst
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Selective oxidation of sulfides to sulfoxides and sulfones is achieved by H2O2 using MoO2Cl2 as the catalyst. Various substituted sulfides having functional groups such as methyl, methoxy, bromo, nitro, alkene, alkyne, alcohol, ester, aldehyde and remarkably an oxime are successfully and selectively oxidized without affecting the sensitive functionalities.
- Jeyakumar, Kandasamy,Chand, Dillip Kumar
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p. 4573 - 4576
(2007/10/03)
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- Oxidations catalyzed by phenylacetone monooxygenase from Thermobifida fusca
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Several organic sulfides, ketones and other organic systems have been tested as substrates in oxidation reactions catalyzed by the recently discovered phenylacetone monooxygenase from Thermobifida fusca. The biocatalytic properties of this Baeyer-Villiger monooxygenase have been studied, revealing reactivity with a large range of sulfides and ketones. Oxidations of several sulfoxides, an amine and an organoboron compound were also observed. The enzyme is able to oxidize a number of sulfides with excellent enantioselectivity, demonstrating the catalytic potential of this novel biocatalyst.
- De Gonzalo, Gonzalo,Torres Pazmino, Daniel E.,Ottolina, Gianluca,Fraaije, Marco W.,Carrea, Giacomo
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p. 3077 - 3083
(2007/10/03)
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- [Cp*Rh(bpy)(H2O)]2+ as a coenzyme substitute in enzymatic oxidations catalyzed by Baeyer-Villiger monooxygenases
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[Cp*Rh(bpy)(H2O)]2+ was applied as a flavin regenerating reagent in BVMO catalyzed oxidations of organic sulfides to chiral sulfoxides. The Royal Society of Chemistry 2005.
- De Gonzalo, Gonzalo,Ottolina, Gianluca,Carrea, Giacomo,Fraaije, Marco W.
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p. 3724 - 3726
(2007/10/03)
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- Azetidine derivatives, their preparation and medicaments containing them
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The invention concerns compounds of formula (1) wherein: R represents a chain (A) or (B); R1 is methyl or ethyl; R2 is either an optionally substituted aromatic or an optionally substituted heteroaromatic ring; R3 and R4, identical or different, are either an optionally substituted aromatic or an optionally substituted heteroaromatic ring; R′ represents a hydrogen atom or a —CO—alk radical, their optical isomers, their salts, their preparation and medicines containing them.
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- Substituent-dictated partitioning of intermediates on the sulfide singlet oxygen reaction surface. A new mechanism for oxidative C-S bond cleavage in α-hydroperoxy sulfides
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The reactions of singlet oxygen with 17 sulfides bearing either anion or radical stabilizing substituents are reported. The abilities of substituents to modify product compositions in both the oxidative cleavage and sulfide oxidation pathways are analyzed in terms of partitioning of the hydroperoxy sulfonium ylide intermediate. Evidence is presented that suggests that the hydroperoxy sulfonium ylide exists in both diradical and zwitterionic forms. In addition, both inter- and intramolecular pathways for decomposition of α-hydroperoxy sulfides are suggested to rationalize the substituent-dependent formation of oxidative C-S bond cleavage products.
- Toutchkine,Aebisher,Clennan
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p. 4966 - 4973
(2007/10/03)
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- The photooxygenation of benzyl, heteroarylmethyl, and allyl sulfides
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The photosensitised oxidation of benzyl ethyl sulfides in aprotic solvents (benzene or acetonitrile) gives the corresponding aldehydes under mild conditions. This is a general reaction which applies to benzyl derivatives containing either electron-donating or electron-withdrawing substituents and furthermore to hereto analogues such as 2-pyridinylmethyl sulfide (not to the 3-indolylmethyl sulfide, since reaction at the heterocycle moiety competes) as well as to allyl sulfides. In a protic solvent (methanol) these sulfides give the sulfoxides instead (except for the nitrobenzyl derivatives, where the aldehyde remains the major product). Among the α-substituted sulfides tested, the α-phenylbenzyl and the 3- cyclohexenyl sulfide give the corresponding ketone (the latter in a low yield), but the α-methylbenzyl sulfide gives the sulfoxide as the main product. The rate for singlet oxygen quenching and for chemical reaction have been measured for representative benzyl sulfides. The reaction is discussed in the frame of the currently accepted mechanism for sulfide photooxygenation. The key step for oxidative C-S bond cleavage appears to be hydrogen transfer from the activated α position in the first formed intermediate, the persulfoxide. This reaction is inhibited in methanol where the persulfoxide is hydrogen-bonded.
- Bonesi, Sergio M.,Torriani, Rosangela,Mella, Mariella,Albini, Angelo
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p. 1723 - 1728
(2007/10/03)
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- Photosensitized oxygenation of some benzyl sulfides. The role of persulfoxide
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Benzyl ethyl sulfide (6a) is photo-oxidized to benzaldehyde in benzene, whereas diethyl sulfide is known to give inefficiently the sulfoxide under these conditions. Oxidative C-S cleavage is the main process also with benzhydryl ethyl sulfide (6c), but not with α-methylbenzyl ethyl sulfide (6b), which mainly gives the sulfoxide. The carbonyl derivatives reasonably arise from S-hydroperoxy ylides (3). Consistently with this finding, calculations at the PM3 level suggest that the first intermediate, the persulfoxide (1), undergoes intramolecular hydrogen transfer when an activated α-hydrogen is available and gives 3. This is the case for the above benzyl sulfides (ΔH* for the process decreases with decreasing C-H BDE). However, only some of the persulfoxide conformations are correctly oriented for this rearrangement, and this may slow this process and make other reactions compete, as happens with 6b. Copyright
- Bonesi, Sergio M.,Freccero, Mauro,Albini, Angelo
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p. 703 - 707
(2007/10/03)
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- Photosensitized oxygenation of benzyl ethyl sulfide
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Singlet oxygen adds to benzyl ethyl sulfide (5, total quenching rate ca. 1 x 107 M-1 s-1, little dependent on the solvent) to ultimately give benzaldehyde (6) and a small amount of the sulfone (8) in aprotic media (rate of the chemical reaction in benzene 5.5 x 106 M-1 s-1) and mainly the sulfoxide (7) in protic media (1.1 x 107 M-1 s-1 in methanol). In the presence of small amounts (0.002-0.3 M) of protic additives (alcohols, phenol, carboxylic acids), the sulfoxide becomes the main product in benzene also. Various evidence support the formation of two intermediates in aprotic solvents. The first one is an exciplex or a syn persulfoxide. It undergoes intramolecular hydrogen abstraction to give a ylide and finally benzaldehyde. Such rearrangement is either a concerted or a radicalic process and not a proton transfer (as indicated by the deuterium effect observed with the α-d benzyl sulfide and the occurrence of the process with the p-nitro and p- methoxy derivatives, 5' and 5''). This intermediate is not quenched except under relatively strong acidic conditions. A second intermediate, arising either from the first one or through a parallel path, has the properties usually associated with the persulfoxide (possibly it is the anti rotamer). This species gives some sulfoxide but mainly decays to the unreacted sulfide; it can be trapped intermolecularly, however, both by acids and by diphenyl sulfoxide (in the latter case it gives more of sulfone 8 than of sulfoxide 7). The relative rates of protonation of both the first and the second intermediate (determined in benzene doped with protic additives) correlate with the gas-phase acidity of such additives. As for the reaction in neat alcohols and in benzene doped with acids, a single intermediate intervenes. This is better described as a S-hydroperoxy cation rather than a neutral hydroperoxysulfurane and is trapped by both diphenyl sulfoxide and sulfone at rates close to those measured for the photo-oxidation of diethyl sulfide.
- Bonesi,Mella,D'Alessandro,Aloisi,Vanossi,Albinit
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p. 9946 - 9955
(2007/10/03)
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- Effect of added benzoic acid on the phase-transfer catalysed permanganate oxidation of organosulfur compounds
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The addition of benzoic acid in the oxidation of a range of sulfides and thiazolidinethiones using KMnO4 under phase-transfer conditions provides a convenient and high yielding procedure for formation of the corresponding sulfones, thiazolidinones and thiazolidinone S,S-dioxides.
- Aitken, R. Alan,Mesher, Shaun T. E.,Ross, Fiona C.,Ryan, Bruce M.
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p. 787 - 791
(2007/10/03)
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- An efficient method for the oxidation of sulfides to sulfones
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Ruthenium trichloride - sodium periodate is a highly efficient and powerful system for the oxidation of unreactive sulfides to sulfones.
- Su, Weiguo
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p. 4955 - 4958
(2007/10/02)
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- A mild, osmium tetraoxide-catalyzed method for the oxidation of sulfides to sulfones
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Osmium tetraoxide has been demonstrated to be a highly efficient catalyst for the chemoselective oxidation of a variety of sulfides to the corresponding sulfones. Tertiary amine catalysis appears to play a key role in the reaction
- Kaldor,Hammond
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p. 5043 - 5046
(2007/10/02)
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- A NEW PROCEDURE FOR OXIDATION OF SULFIDES TO SULFONES
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A series of variously substituted sulfones has been synthesized by oxidation of the corresponding sulfides with the hydrogen peroxide/selenium dioxide system.Very short reaction time, easy work-up and high yields make this new preparation of sulfones a recommendable method.
- Drabowicz, Jozef,Lyzwa, Piotr,Mikolajczyk, Marian
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p. 169 - 172
(2007/10/02)
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