- Generation of the Methoxycarbonyl Radical by Visible-Light Photoredox Catalysis and Its Conjugate Addition with Electron-Deficient Olefins
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Visible-light photoredox-catalyzed fragmentation of methyl N-phthalimidoyl oxalate allows the direct construction of a 1,4-dicarbonyl structural motif by a conjugate addition of the methoxycarbonyl radical to reactive Michael acceptors. The regioselectivity of the addition of this alkoxyacyl radical species to electron-deficient olefins is heavily influenced by the electronic nature of the acceptor, behavior similar to that exhibited by nucleophilic alkyl radicals.
- Slutskyy, Yuriy,Overman, Larry E.
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- Multicomponent Synthesis of Sulfones and Sulfides from Triarylbismuthines and Sodium Metabisulfite in Deep Eutectic Solvents
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This study describes a novel and catalyst-free methodology for the multicomponent synthesis of a broad range of sulfones, disulfides, and sulfides from non-toxic triarylbismuthines (Ar3Bi) and sodium metabisulfite (Na2S2O5) in deep eutectic solvents (DESs). The fine tuning of the DESs properties allowed the solubility of all reagents, enhancing their reactivity, as well as, the recyclability of the reaction medium for at least 5 consecutive cycles. Thus, this versatile strategy uses non-toxic reagents without the need of metal catalysts in a sustainable solvent, being an interesting alternative to traditional hazardous protocols.
- Saavedra, Beatriz,Marset, Xavier,Guillena, Gabriela,Ramón, Diego J.
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supporting information
p. 3462 - 3467
(2020/06/04)
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- Catalyst-free oxidation of sulfides to sulfoxides and diethylamine catalyzed oxidation of sulfides to sulfones using Oxone as an oxidant
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Abstract: We describe here our journey from the failure of our attempts in controlled oxidation of sulfides to sulfoxides using an Oxone–KBr combination to our success in the development of a catalyst-free protocol for the oxidation of sulfides to sulfoxides using Oxone as an oxidant. We also describe the failure of our attempts at the oxidation of sulfides to sulfones using an excess of Oxone–KBr as well as Oxone, and our success towards the development of a rapid, scalable and chromatography-free protocol for the oxidation of sulfides to sulfones using diethylamine–Oxone as an unprecedented catalyst–oxidant combination.
- Kupwade,Khot,Lad,Desai,Wadgaonkar
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p. 6875 - 6888
(2017/10/06)
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- Deep Eutectic Solvents as Reaction Media for the Palladium-Catalysed C?S Bond Formation: Scope and Mechanistic Studies
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A unique jigsaw catalytic system based on deep eutectic solvents and palladium nanoparticles where C?S bonds are formed from aryl boronic acids and sodium metabisulfite, is introduced. The functionalization step is compatible with a broad spectrum of reagents such as nucleophiles, electrophiles or radical scavengers. This versatile approach allows the formation of different types of products in an environmentally friendly medium by selecting the components of the reaction, which engage one with another as pieces in a jigsaw. This simple procedure avoids the use of toxic volatile organic solvents allowing the formation of complex molecules in a one-pot reaction under mild conditions. Despite the fact that only 1 mol % of metal loading is used, the recyclability of the catalytic system is possible. Kinetic experiments were performed and the reaction order for all reagents, catalyst and ligand was determined. The obtained results were compared to palladium nanocrystals of different known shapes in order to shed some light on the properties of the catalyst.
- Marset, Xavier,Guillena, Gabriela,Ramón, Diego J.
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supporting information
p. 10522 - 10526
(2017/08/10)
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- Synthesis of alkyl aryl sulfones via reaction of N-arylsulfonyl hydroxyamines with electron-deficient alkenes
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Alkyl aryl sulfones were prepared in high yields via the reaction of N-arylsulfonyl hydroxylamines with electron-deficient alkenes. These reactions have the advantages of simplicity, easily available starting materials and mild reaction conditions.
- Bin, Yunhui,Hua, Ruimao
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- Method for preparing substituted ethyl aryl sulfone
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The invention discloses a method for preparing substituted ethyl aryl sulfone. The method comprises the following steps: a compound shown in a formula II, a compound shown in a formula III and alkali are uniformly mixed in a solvent and are subjected to a coupling reaction, a compound shown in a formula I containing R2' as -CH2CH2R is obtained after the reaction is complete; or the method comprises the following steps: the compound shown in the formula II, ethyl propiolate and alkali are uniformly mixed in the solvent and then are subjected to the coupling reaction, and the compound shown in a formula I containing R2' as -CH=CH2=OOCH2CH3 is obtained after the reaction is complete. The method has the advantages of universality, convenience, simple reaction system, and mild reaction condition; the reaction can be amplified to a gram level, the reaction raw materials are simple and easily available, the used alkali and raw materials have the advantages of low cost and easy acquisition, the atom utilization rate is high, and solvent toxicity is low.
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Paragraph 0044-0045
(2017/03/23)
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- Addition of sulfinic acids to methacrylic derivatives
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The kinetics of the addition of arenesulfinic acids to methacrylic derivatives were studied. The reactions were found to be second order over a range of concentrations from 0.01 to 0.10 M. For pH values ranging from 4 to 8, the following rate constants were obtained pH the methylacrylate, chloromethylacrylate, and bromomethylacrylate with benzenesulfinic acids (278 K) were investigated: 2.37 (± 0.2).10-4 M-1s -1, 2.60 (± 0.1).10-4 M-1s-1, 3.15 (± 0.3).10-4 M-1s-1. Copyright Taylor & Francis Group, LLC.
- Ivanova,Aleksiev
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experimental part
p. 38 - 43
(2011/03/22)
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- Borax-catalyzed and pH-Controlled selective oxidation of organic sulfides by H2O2: An environmentally clean protocol
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The selective oxidation of sulfides to sulfoxides and sulfones was achieved in high yields at: room temperature with borax as a recyclable catalyst and H2O2 as the terminal oxidant by varying the pH of the reaction medium. The borax/H2O2 system can chemoselectively oxidize alkyl and aryl sulfides in the presence of oxidation-prone functional, groups such as C=C, -CN, and -OH.
- Hussain, Sahid,Bharadwaj, Saitanya K.,Pandey, Ravindra,Chaudhuri, Mihir K.
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experimental part
p. 3319 - 3322
(2011/03/17)
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- Chemoselective sulfoxidation by H2O2 or HNO3 using a phosphate impregnated titania catalyst
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A variety of organosulfur compounds have been selectively oxidized to the corresponding sulfoxides by either H2O2 or HNO3 using a newly developed solid acid catalyst composed of 84.5% of TiO2 and 15.5% of [Ti4H11(PO4)9]·nH2O (n = 1-4). The chemoselective oxidation of sulfides in the presence of vulnerable groups such as -CN, -C{double bond, long}C-, -CHO, or -OH, as well as sulfoxidation of substrates like benzothiazole, glycosyl sulfide, and dibenzothiophenes is some of the important attribute of the protocol. Nitric acid, under the present experimental conditions, brings about relatively better selectivity than hydrogen peroxide.
- Bharadwaj, Saitanya K.,Sharma, Susanda N.,Hussain, Sahid,Chaudhuri, Mihir K.
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experimental part
p. 3767 - 3771
(2009/10/11)
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- Tin-free, radical-mediated γ-alkylations of α,β- unsaturated esters via O-tert-alkyl dienol ethers
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Tin-free, radical-mediated γ-alkylation of α,β-unsaturated esters is accomplished by radical addition and β-fragmentation of O-tert-alkyl dienol ethers and subsequent iodine atom transfer process. Georg Thieme Verlag Stuttgart.
- Jin, Young Lee,Kim, Sunggak
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- Radical alkylation of bis(silyloxy)enamine derivatives of organic nitro compounds
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(Chemical Equation Presented) Alkylation β to a nitro group by radical chemistry is made possible by initial conversion of the organic nitro compound into a bis(silyloxy)enamine (see scheme; TBSOTf=tert-butyldimethylsilyl trifluoromethanesulfonate). An advantage of the method is the simultaneous conversion of the nitro group into a synthetically useful oxime ether group.
- Jin, Young Lee,Hong, Young-Taek,Kim, Sunggak
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p. 6182 - 6186
(2007/10/03)
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- Phase-Vanishing Methodology for Efficient Bromination, Alkylation, Epoxidation, and Oxidation Reactions of Organic Substrates
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(Matrix presented) In cases where both reactants in a phase-vanishing reaction are less dense than the fluorous phase, an alternative to the U-tube method is to employ a solvent with greater density than the fluorous phase, such as 1,2-dibromoethane. This modification has been successfully applied to the methylation of a phenol derivative with dimethyl sulfate and to the m-CPBA-induced epoxidation of alkenes, N-oxide formation from nitrogen-containing compounds, and S-oxide or sulfone formation from organic sulfides.
- Jana, Nirmal K.,Verkade, John G.
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p. 3787 - 3790
(2007/10/03)
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- Efficient synthesis and biological evaluation of all A-ring diastereomers of 1α,25-dihydroxyvitamin D3 and its 20-epimer
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An improved synthesis of the diastereomers of 1α,25-dihydroxyvitamin D3 (1) was accomplished utilizing our practical route to the A-ring synthon. We applied this procedure to synthesize for the first time all possible A- ring diastereomers of 20-epi-1α,25-dihydroxyvitamin D3 (2). Ten-step conversion of 1-(4-methoxyphenoxy)but-3-ene (6), including enantiomeric introduction of the C-3 hydroxyl group to the olefin by the Sharpless asymmetric dihydroxylation, provided all four possible stereoisomers of A- ring enynes (3), i.e., (3R,5R)-, (3R,5S)-, (3S,5R)- and (3S,5S)-bis[(tert- butyldimethylsilyl)oxy]oct-1-en-7-yne, in good overall yield. Palladium- catalyzed cross-coupling of the A-ring synthon with the 20-epi CD-ring portion (5), (E)-(20S)-de-A,B-8-(bromomethylene)cholestan-25-ol, followed by deprotection, afforded the requisite diastereomers of 20-epi-1α,25- dihydroxyvitamin D3 (2). The biological profiles of the synthesized stereoisomers were assessed in terms of affinities for vitamin D receptor (VDR) and vitamin D binding protein (DBP), HL-60 cell differentiation- inducing activity and in vivo calcium-regulating potency in comparison with the natural hormone. (C) 2000 Elsevier Science Ltd.
- Fujishima, Toshie,Konno, Katsuhiro,Nakagawa, Kimie,Kurobe, Mayuko,Okano, Toshio,Takayama, Hiroaki
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p. 123 - 134
(2007/10/03)
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- Oxidative addition of thiols to substituted olefins in the presence of transition metal peroxo complexes under phase-transfer catalysis conditions
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Oxidative addition of thiophenol and isobutanethiol to substituted olefins in the presence of molybdenum, tungsten, and vanadium peroxo complexes under phase-transfer catalysis conditions was shown to give sulfones, the oxidation products of sulfides formed in the first step, and disulfides as the oxidation products of thiols. The product ratio of the reaction depends on the structure of an olefin, thiol, and the peroxo complex used. Copyright 1999 by MAHK "Hayka/Interperiodica" (Russia).
- Zhirukhina,Thanaa, Al-Haddad,Tarakanova,Litvinova,Kulikov,Anisimov
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p. 105 - 107
(2007/10/03)
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- An efficient oxidation of sulfides to sulfones using 2-methylpropanal and dioxygen
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A wide range of sulfides can be oxidized to the corresponding sulfones in high yields in the presence of molecular oxygen and five equivalent of 2-methylpropanal at 70°C.
- Khanna, Vibha,Maikap, Golak C.,Iqbal, Javed
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p. 3367 - 3370
(2007/10/03)
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- Reactions of Organic Anions; CXLIX. Reactions of gem-Dichlorocyclopropanes Containing an Electron-Withdrawing Substituent with Organic Anions Generated with Phase-Transfer Catalysis
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gem-Dichlorocyclopropanes 1 react with C-H, O-H and S-H acids in the presence of concentrated sodium hydroxide solution and a phase-transfer catalyst to give gem-disubstituted cyclopropanes 2 or chain products 3 in 44-95percent yield.
- Fedorynski, Michal,Dybowska, Agnieszka,Jonczyk, Andrzej
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p. 549 - 551
(2007/10/02)
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