- Highly chemoselective synthesis of aryl allylic sulfoxides through calcium hypobromite oxidation of aryl allylic sulfides
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A highly chemoselective oxidation of widely substituted aryl allylic sulfides, prepared by allylation of arylthioethers with KF-Celite, to the corresponding aryl allylic sulfoxide was achieved by employing calcium hypobromite. Neither over-oxidation to sulfones nor halogenation of the aromatic rings was observed. The protocol may be successfully applied for the oxidation of substituted allylic systems (i.e., 2-haloallyl) that per se could interact with the oxidizing agent.
- Pace, Vittorio,Castoldi, Laura,Holzer, Wolfgang
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p. 967 - 972
(2012/03/11)
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- Diketopiperazine-derived hydroperoxide for chemoselective oxidations of sulfides and enantioselective Weitz-Scheffer epoxidations
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l-Proline-derived hydroperoxide (-)-2, which was obtained from the corresponding diketopiperazine by irradiation under oxygen atmosphere, was applied to the oxidation of a variety of sulfides and asymmetric Weitz-Scheffer epoxidations of cyclic and acycli
- Kienle, Marcel,Argyrakis, Wassiliki,Baro, Angelika,Laschat, Sabine
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p. 1971 - 1974
(2008/09/19)
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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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- Synthesis of Sulfoxides by the Hydrogen Peroxide Induced Oxidation of Sulfides Catalyzed by Iron Tetrakis(pentafluorophenyl)porphyrin: Scope and Chemoselectivity
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The oxidation of sulfides with H2O2 catalyzed by iron tetrakis(pentafluorophenyl)porphyrin in EtOH is an efficient and chemoselective process. With a catalyst concentration 0.03-0.09% of that of the substrate, sulfoxides are obtained with yields generally around 90-95% of isolated product. With vinyl and allyl sulfides, no epoxidation is observed. With a catalyst concentration between 0.09% and 0.25% of that of the substrate, sulfones are obtained in almost quantitative yield and with the same high chemoselectivity observed in the synthesis of sulfoxides.
- Baciocchi, Enrico,Gerini, Maria Francesca,Lapi, Andrea
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p. 3586 - 3589
(2007/10/03)
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- Highly selective sulfoxidation of allylic and vinylic sulfides by hydrogen peroxide using a flavin as catalyst
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A highly chemoselective oxidation of allylic and vinylic sulfides to the corresponding sulfoxides has been developed using flavin 1 as the oxidation catalyst and hydrogen peroxide as the terminal oxidant. The sulfoxides were formed in good to excellent yields in a highly selective manner even when an excess of the oxidant was used. Sulfone formation was completely suppressed to 0.5% (in one single case 1.5% sulfone was detected). No epoxidation of double bonds or interference with other functional groups was observed under the reaction conditions. The general applicability was demonstrated by the selective oxidation of various allylic and vinylic sulfides having different electronic properties. A number of functionalities including hydroxy, acetoxy, amino, silyloxy, and formyl groups are tolerated under these mild reaction conditions.
- Linden, Auri A.,Krueger, Lars,Baeckvall, Jan-E.
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p. 5890 - 5896
(2007/10/03)
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- Mild and highly chemoselective oxidation of thioethers mediated by Sc(OTf)3
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(Matrix presented) Catalytic Sc(OTf)3 greatly increases the efficiency of hydrogen peroxide mediated monooxidation of alkyl-aryl sulfides and methyl cysteine containing peptides. The method is high yielding, compatible with many widely used protecting groups, suitable for solid-phase applications and proceeds with minimum over-oxidation.
- Matteucci, Mizio,Bhalay, Gurdip,Bradley, Mark
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p. 235 - 237
(2007/10/03)
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- Selective oxidation of allylic sulfides by hydrogen peroxide with the trirutile-type solid oxide catalyst LiNbMoO6
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Chemoselective sulfur oxidation of allylic sulfides containing double bonds of high electron density due to multiple alkyl substituents or extended conjugation was developed using the composite metal oxide catalyst, LiNbMoO6, without any epoxidation of the electron-rich double bond(s). Selective oxidation to either the corresponding sulfoxides or the sulfones was realized by controlling the stoichiometry of the quantitative oxidant, H202. This new oxidant system had general applicability for chemoselective oxidation of various allylic, benzylic, or propargylic sulfides containing unsaturated carbon-carbon bonds with different electron properties. Various functional groups including hydroxy, formyl, and ethers of THP or TBDMS are compatible under this mild oxidation reaction condition.
- Choi, Soojin,Yang, Jae-Deuk,Ji, Minkoo,Choi, Hojin,Kee, Minyong,Ahn, Kwang-Hyun,Byeon, Song-Ho,Baik, Woonphil,Koo, Sangho
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p. 8192 - 8198
(2007/10/03)
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- SPIN TRAPPING STUDIES OF PEROXYL RADICALS. DETECTION OF THE REACTIVE INTERMEDIATES FOR OXIDATION GENERATED FROM O2-. AND SULFONYL, SULFINYL AND PHOSPHORYL CHLORIDES
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The spin trapping studies by ESR have demonstrated that O2-. efficiently reacts with 2-nitrobenzenesulfonyl chloride, 2-nitrobenzenesulfinyl chloride, and diphenylphosphoryl chloride, to result in the formation of their peroxyl radicals, some of which have been key intermediates for site-selective oxidation of certain organic molecules and argued whether they exist as anion and/or radical form.
- Kim, Yong Hae,Lim, Sang Chul,Hoshino, Mikio,Ohtsuka, Yasuo,Ohishi, Takeshi
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p. 167 - 170
(2007/10/02)
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- Aprotic Conjugate Addition of Allyllithium Reagents Bearing Polar Groups to Cyclic Enones. 1. 3-Alkylallyl Systems
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The conjugate addition of lithiated (E)- and (Z)-oct-2-enyl sulfoxides and phosphine oxides, but-2-enyl sulfoxides, phosphine oxides and phosphonates, and 3,3-dimethylallyl and allyl sulfoxides to cyclic enones has been examined.The E and Z carbanions react in highly diastereoselective fashion with five-membered cyclic enones to deliver respectively syn and anti vinylic sulfoxides, phosphine oxides, and phosphonates.Hexamethylphosphoric triamide has no regiochemical influence on these reactions.The regiochemical and stereochemical outcomes of these reactions are rationalized in terms of planar lithiated reagents in which Li+ is bound to oxygen attached to sulfur or phosphorus of the polar group and a 10-membered "trans-decalyl"- or "trans-fused chair-chair"-like transition-state model in which the lithiated reagent adopts an endo orientation over one face of the enone such that for the reagent, the 3-alkyl group is pseudoequatorial, and for the Z, pseudoaxial.
- Binns, Malcolm R.,Haynes, Richard K.,Katsifis, Andrew G.,Schober, Paul A.,Vonwiller, Simone C.
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p. 5411 - 5423
(2007/10/02)
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- 3-Chloro-2-chloromethyl-4-(4-chlorophenoxy)-1-butene as a Functionalized Isoprene Unit. An Electrochemical Preparation and Some Reactions
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3-Chloro-2-chloromethyl-4-(4-chlorophenoxy)-1-butene (1) was prepared in 72percent yield by electrooxidative double ene-type chlorination of 1-(4-chlorophenoxy)-3-methyl-2-butene.The electrolysis was conducted at room temperature in a two layer solvent sy
- Uneyama, Kenji,Hasegawa, Nobu,Kawafuchi, Hiroyuki,Torii, Sigeru
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p. 1214 - 1218
(2007/10/02)
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