- Chiral Ligands in Hypervalent Iodine Compounds: Synthesis and Structures of Binaphthyl-Based λ3-Iodanes
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Several novel binaphthyl-based chiral hypervalent iodine(III) reagents have been prepared and structurally analysed. Various asymmetric oxidative reactions were applied to evaluate the reactivities and stereoselectivities of those reagents. Moderate to excellent yields were observed; however, very low stereoselectivities were obtained. NMR experiments indicated that these reagents are very easily hydrolysed in either chloroform or DMSO solvents leading to the limited stereoselectivities. It is concluded that the use of chiral ligands is an unsuccessful way to prepare efficient stereoselective iodine(III) reagents.
- Zhang, Huaiyuan,Cormanich, Rodrigo A.,Wirth, Thomas
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supporting information
(2021/12/22)
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- Diastereoselective oxidation of menthyl arenesulfenates to sulfinates and access to enantioenriched aryl methyl sulfoxides
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Three aryl methyl sulfoxides were prepared via the following sequence: synthesis of the menthyl arenesulfenate from the corresponding thiol, diastereoselective oxidation leading to the sulfinate, then reaction with a Grignard reagent. The aryl moiety was substituted with a methyl ester on the ortho position or a nitro group on the ortho or the para position. The sulfenate esters were obtained in fair to excellent yield (42–82%). Four different oxidizing agents were tested to obtain the corresponding sulfinate esters with diastereomeric excesses (de) ranging from 10 to 48%. After separation of the diastereomers and reaction with methyl Grignard reagent, two enantiopure sulfoxides and one enantioenriched sulfoxide (32% ee) were obtained.
- Hamel, Matthieu,Vazeux, Michel,Gulea, Mihaela
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p. 6137 - 6143
(2021/07/12)
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- Chiral: N, N ′-dioxide-iron(iii)-catalyzed asymmetric sulfoxidation with hydrogen peroxide
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A highly enantioselective sulfoxidation of various sulfides has been achieved by a N,N′-dioxide-iron(iii) complex with 35% aq. H2O2 as the oxidant. The utility of the current method was demonstrated by asymmetric gram-scale synthesis of drug molecule (R)-modafinil. Moreover, a possible working mode was provided to elucidate the chiral induction.
- Dong, Shunxi,Feng, Lili,Feng, Xiaoming,Liu, Xiaohua,Wang, Fang
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supporting information
p. 3233 - 3236
(2020/03/23)
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- An efficient silica supported Chitosan@vanadium catalyst for asymmetric sulfoxidation and its application in the synthesis of esomeprazole
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A new type of silica supported Chitosan@vanadium complex was used as a highly active heterogeneous catalyst for asymmetric oxidation of aryl alkyl sulfides. With the economic aqueous H2O2(30%) as the oxidant, the oxidation products were obtained in high yields (up to 95%) with good enantioselectivities (up to 68% ee). It is noted that the marketed drug Nexium (first proton-pump inhibitor, esomeprazole) could be synthesized easily by the newly developed asymmetric sulfoxidation reaction. In addition, the highly active catalyst can be reused five times without losing its catalytic activity.
- Shen, Chao,Qiao, Jun,Zhao, Linwei,Zheng, Kai,Jin, Jianzhong,Zhang, Pengfei
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p. 114 - 118
(2017/01/25)
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- Bio-inspired single-chain polymeric nanoparticles containing a chiral salen TiIV complex for highly enantioselective sulfoxidation in water
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A series of bio-inspired single-chain polymeric nanoparticles (SCPNs) containing a chiral salen TiIV complex in their hydrophobic cavity were constructed from the synthesized amphiphilic copolymers of poly(NIPAAm-co-IL/Ti(salen)) (NIPAAm, N-isopropylacrylamide; IL/Ti(salen), vinylimidazolium ionic liquid-modified chiral salen TiIV complex). These SCPNs behaved as enzyme-mimetic catalysts due to compartmentalization and site isolation, mediating enantioselective oxidation of various sulfides in water with excellent yields (90-99%) and enantioselectivities (ee, 88-99%). In particular, the ee values observed for electron-rich substrates (>95% ee) represented the best results so far in titanium-salen systems. Moreover, the catalysts could be easily recovered for steady reuse by thermo-controlled separation due to thermo-responsive properties. This work first constructed titanium-containing biomimetic SCNPs for biocatalysis of enantioselective sulfoxidation in water.
- Zhang, Yaoyao,Tan, Rong,Gao, Mengqiao,Hao, Pengbo,Yin, Donghong
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p. 1182 - 1193
(2017/08/14)
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- Cooperative chiral salen TiIV catalyst supported on ionic liquid-functionalized graphene oxide accelerates asymmetric sulfoxidation in water
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A cooperative chiral salen TiIV catalyst was prepared by covalently appending multiple chiral salen TiIV complexes on a graphene oxide (GO) surface through a flexible ionic liquid (IL) linker. Characterization results confirmed the decoration of intact Ti(salen) units on the edges and planes of exfoliated GO with the imidazolium-IL spacer. The IL-functionalized GO nanosheets endowed the chiral salen TiIV catalyst with high water-dispersion, diminished diffusion limitation, and particularly a reinforced intramolecular cooperative effect. The cooperative catalyst was thus highly efficient and universally applicable in the catalysis of asymmetric sulfoxidation in water, affording high yields of various chiral sulfoxides with excellent enantioselectivities, while traditional chiral salen TiIV complex was far less active. More importantly, the heterogeneous catalyst was perfectly stable and could be reused several times without significant loss of activity and selectivity.
- Xing, Chen,Deng, Jiang,Tan, Rong,Gao, Mengqiao,Hao, Pengbo,Yin, Donghong,Yin, Dulin
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p. 5944 - 5952
(2017/12/26)
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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; 0031
(2017/08/30)
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- HPLC enantioseparation on a homochiral MOF-silica composite as a novel chiral stationary phase
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The last frontier in the development of chiral stationary phases for chromatographic enantioseparation involves homochiral metal-organic frameworks (MOFs). Using enantiopure (R)-2,2′-dihydroxy-1,1′-binaphthalene-6,6′-dicarboxylic acid as a starting material, we prepared three homochiral MOFs that were further used as chiral stationary phases for high-performance liquid chromatography to separate the enantiomers of various kinds of racemic sulfoxides, sec-alcohols, β-lactams, benzoins, flavanones and epoxides. The experimental results showed excellent performances for enantioseparation, and highlighted that enantioseparation on homochiral MOF columns is practical.
- Tanaka, Koichi,Muraoka, Toshihide,Otubo, Yasuhiro,Takahashi, Hiroki,Ohnishi, Atsushi
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p. 21293 - 21301
(2016/03/08)
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- Efficient HPLC enantiomer separation using a pillared homochiral metal-organic framework as a novel chiral stationary phase
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HPLC enantioseparation of racemates using novel pillared homochiral metal-organic framework-silica composite as chiral stationary phase has been successfully demonstrated.
- Tanaka, Koichi,Hotta, Naoki,Nagase, Shohei,Yoza, Kenji
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supporting information
p. 4891 - 4894
(2016/07/06)
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- Method for realizing asymmetric oxidation reaction of thioether under aqueous-phase catalysis of chiral Salen Ti complex catalyst based on temperature-sensitive type ionic liquid
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The invention discloses a method for realizing an asymmetric oxidation reaction of thioether under aqueous-phase catalysis of a chiral Salen Ti complex catalyst based on a temperature-sensitive type ionic liquid. According to the method, a chiral thioether compound and hydrogen peroxide are subjected to an asymmetric oxidation reaction under the catalytic action of the chiral Salen Ti complex catalyst based on the temperature-sensitive type ionic liquid in a water medium, and a chiral sulfoxide compound is obtained; the chiral Salen Ti complex catalyst based on the temperature-sensitive type ionic liquid also contains a chiral Salen Ti complex catalyst unit and a temperature-sensitive material unit. Compared with a conventional chiral Salen Ti catalyst, the catalyst has good water solubility, can be subjected to a catalytic reaction in the water medium and is easily recycled; the catalyst is applicable to the aqueous-phase catalytic oxidation reaction of chiral thioether and has the characteristics of high catalysis efficiency and good chiral sulfoxide selectivity.
- -
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Paragraph 0087-0089
(2017/02/24)
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- Cooperative chiral salen TiIV catalysts with built-in phase-transfer capability accelerate asymmetric sulfoxidation in water
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A series of cooperative chiral salen TiIV catalysts with inherent phase-transfer capability were prepared by covalently bridging double chiral salen TiIV units with various polyethylene glycol (PEG)-based dicationic ionic liquid (IL) linkers. Characterization results suggested the presence of polyether-based IL spacers and intact active sites in the catalysts. The polyether-based dicationic IL spacer not only enforced an intramolecular, cooperative reaction pathway favored for the asymmetric suloxidation, but also endowed the bimetallic catalysts with built-in phase transfer capability. High yields of chiral sulfoxides (in the range of 74-90%) with excellent ee values (in the range of 85-91%) were achieved within 45 min when the asymmetric oxidation of methyl phenyl sulfide, methyl p-methoxyphenyl sulfide, and methyl o-methoxyphenyl sulfide were performed in water. The catalytic efficiency was significantly higher than that over neat complex (yields, 10-16% and ee values, 77-79%). More attractively, the phase transfer catalysts could be facilely recovered by solvent precipitation for efficient reuse.
- Zhao, Guangwu,Tan, Rong,Zhang, Yaoyao,Luo, Xuanfeng,Xing, Chen,Yin, Donghong
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p. 24704 - 24711
(2016/03/15)
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- Thermo-responsive self-assembled metallomicelles accelerate asymmetric sulfoxidation in water
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A series of novel chiral salen TiIV catalysts with thermo-responsive surfactant properties were prepared by covalently appending a chiral salen TiIV complex on the hydrophobic block of thermo-responsive amphiphilic copolymers of poly(N-isopropylacrylamide-co-N,N-dimethyl acrylamide) (poly (NIPAAM-co-DMAAM)). Characterization results suggested self-assembly behavior of the catalysts in water at room temperature. The self-assembled metallomicelles induced a micellar catalytic approach in asymmetric sulfoxidation in water using H2O2 as an oxidant, leading to significant rate acceleration and remarkable high selectivity. Quantitative conversion (>99%) of methyl phenyl sulfide with up to 96% chemoselectivity and 95% enantioselectivity was achieved over 0.5 mol% of PN70D7-C even within 30 min, whereas neat complex was far less efficient (9% conversion with 72% chemoselectivity and 79% enantioselectivity). Moreover, the catalysts could be easily recovered by thermo-controlled separation and be efficiently reused for several cycles.
- Zhang, Yaoyao,Tan, Rong,Zhao, Guangwu,Luo, Xuanfeng,Xing, Chen,Yin, Donghong
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- Dendritic Chiral Salen Titanium(IV) Catalysts Enforce the Cooperative Catalysis of Asymmetric Sulfoxidation
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A series of new dendritic chiral salen TiIV catalysts was prepared by the covalent confinement of multiple chiral salen TiIV complexes on the periphery of a polyamidoamine (PAMAM) dendrimer through a flexible ionic liquid (IL) linker. The characterization results suggested the presence of a dendritic PAMAM scaffold, IL spacer, and intact peripheral active sites in the catalysts. The unique dendritic structure of catalysts together with a flexible IL spacer enforced the intramolecular, cooperative catalysis of asymmetric sulfoxidation to result in improved catalytic efficiency and, especially, a remarkably high selectivity. A chemoselectivity of 90 % with an enantioselectivity of 85 % was obtained in the asymmetric sulfoxidation of methyl phenyl sulfide catalyzed by the dendritic catalyst, which was significantly higher than that observed for the neat complex (64 % chemoselectivity with 68 % enantioselectivity). Furthermore, the catalysts could be recovered easily by solvent precipitation for efficient reuse.
- Chen, Yaju,Tan, Rong,Zhang, Yaoyao,Zhao, Guangwu,Yin, Donghong
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p. 4066 - 4075
(2015/12/26)
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- Bimetallic titanium complex catalyzed enantioselective oxidation of thioethers using aqueous H2O2 as a terminal oxidant
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A series of dimeric amino alcohol derived Schiff bases with various chiral amino alcohols and their corresponding bimetallic titanium complex were generated in situ. Thereafter with the in situ generated complexes, the asymmetric oxidation of prochiral aryl alkyl sulfides has been investigated using aqueous H2O2 as a terminal oxidant. During the study we found that the use of methanol or tert-butanol as an additive improved the catalytic activity in terms of both conversion and enantioselectivity. Moreover we observed a co-operative effect of the two reactive units of the bimetallic complex, which results in high reactivity as well as enantioselectivity compared to the corresponding monomeric complex. With this improved catalytic system several aryl alkyl sulfides and 1,3-dithianes were oxidised to the corresponding sulfoxides with good to high enantioselectivity (ee 78-99%) and conversion (70-99%). Unlike the monomer, oxidation of substrates like benzyl phenyl sulfide was achieved with high enantioselectivity as well as high yield.
- Bera, Prasanta Kumar,Gupta, Naveen,Abdi, Sayed H. R.,Khan, Noor-Ul H.,Kureshy, Rukhsana I.,Bajaj, Hari C.
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p. 47732 - 47739
(2015/06/16)
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- Iron-catalyzed imidative kinetic resolution of racemic sulfoxides
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Kinetic resolution of racemic sulfoxides requires either custom substrates or shows moderate enantioselectivity, leading to achiral coproducts (such as sulfones) as an intrinsic part of the process. A new strategy is demonstrated that allows the resolution of racemic sulfoxides through catalytic asymmetric nitrene-transfer reactions. This approach gives rise to both optically active sulfoxides and highly enantioenriched sulfoximines. By using a chiral iron catalyst and a readily available iodinane reagent, high selectivity factors have been achieved under very practical reaction conditions. With respect to the substrate scope, it is noteworthy that this unprecedented imidative kinetic resolution of racemic sulfoxides provides access to both aryl-alkyl and dialkyl sulfoximines in highly enantioenriched forms. Copyright
- Wang, Jun,Frings, Marcus,Bolm, Carsten
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supporting information
p. 966 - 969
(2014/02/14)
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- PROCESS FOR THE ASYMMETRIC OXIDATION OF ORGANIC COMPOUNDS WITH PEROXIDES IN THE PRESENCE OF A CHIRAL ACID CATALYST
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The present invention relates to a process for the asymmetric oxidation of nucleophilic organic compounds, particularly metal-free, with peroxide compounds in the presence of a chiral Bronsted acid catalyst. In one detail, the present invention relates to a process for enantioselective sulfoxidation of thiocompounds with peroxide compounds in the presence of a chiral imidodiphosphate catalyst. In another detail, the present invention relates to a process for enantioselective sulfoxidation of thiocompounds with peroxide compounds in the presence of a chiral phosphoric acid catalyst.
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Page/Page column 25-27
(2013/07/25)
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- Synthesis of novel β-amino alcohols and their application in the catalytic asymmetric sulfoxidation of sulfides
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Novel chiral norephedrine-based β-amino alcohol ligands containing a thiophene ring were prepared from norephedrine and substituted furan carbaldehydes (methyl- or ethyl-substituted) and used in combination with VO(acac)2 for the asymmetric oxidation of aryl methyl sulfides using H2O2 as an oxidant. Amino alcohol derived Schiff bases 4,5a-b gave higher enantiomeric excesses than amino alcohol-derived reduced Schiff based ligands 6,7a-b. Of these chiral ligands, (1S,2R)-5b and (1S,2R)-7b gave high yields (90%) with moderate to high enantioselectivities (78%, 96% ee, respectively). The oxidation of other aryl methyl sulfides with (1S,2R)-5b and (1S,2R)-7b as ligands afforded the corresponding sulfoxides in 60-89% yields and with 92-99% ee.
- Aydin, A. Ebru
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p. 444 - 448
(2013/06/26)
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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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- A chiral porous metallosalan-organic framework containing titanium-oxo clusters for enantioselective catalytic sulfoxidation
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A chiral porous zeolite-like metal-organic framework is constructed by using mixed ligands of dipyridyl-functionalized chiral Ti(salan) and biphenyl-4,4′-dicarboxylate. The framework containing salan-bound Ti 4O6 clusters consists of both hydrophobic and amphiphilic mesocages and is shown to be an efficient and recyclable heterogeneous catalyst for the oxidation of thioethers to sulfoxides by aqueous H2O 2 (up to 82% ee), displaying markedly enhanced enantioselectivity over the homogeneous catalyst by providing a cavity confinement effect. This work highlights the potential of significantly improving enantioselectivity of homogeneous catalysts by using MOFs as support structures.
- Xuan, Weimin,Ye, Chengcheng,Zhang, Mengni,Chen, Zhijie,Cui, Yong
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p. 3154 - 3159
(2013/07/26)
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- Asymmetric oxidation of sulfides by hydrogen peroxide catalyzed by chiral manganese porphyrins in water/methanol solution
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An efficient asymmetric oxidation of sulfides catalyzed by water-soluble chiral manganese porphyrin was carried out in presence of cheap and environmentally benign oxidant H2O2 at 25 °C. Prochiral sulfides were converted to respective sulfoxides with up to 100% conversion and up to 57% enantiomeric excess. The present study demonstrated the necessity of water as solvent and imidazole as co-catalyst. Application to the preparation of the optically drug, sulindac, was demonstrated.
- Srour, Hassan,Jalkh, Joanna,Le Maux, Paul,Chevance, Soizic,Kobeissi, Marwan,Simonneaux, Gérard
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- Chiral microporous Ti(salan)-based metal-organic frameworks for asymmetric sulfoxidation
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Chiral porous metal-metallosalan frameworks are constructed from an unsymmetrical chiral pyridinecarboxylate ligand derived from Ti(salan) and are shown to be heterogeneous catalysts for asymmetric oxidation of thioethers to sulfoxides.
- Zhu, Chengfeng,Chen, Xu,Yang, Zhiwei,Du, Xia,Liu, Yan,Cui, Yong
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p. 7120 - 7122
(2013/08/23)
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- Activation of H2O2 by chiral confined Bronsted acids: A highly enantioselective catalytic sulfoxidation
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Confined chiral Bronsted acids are shown to catalyze asymmetric oxidations of sulfides to sulfoxides with hydrogen peroxide. The wide generality and high enantioselectivity of the developed method compare even to the best metal-based systems and suggest utility in other asymmetric oxidations.
- Liao, Saihu,Coric, Ilija,Wang, Qinggang,List, Benjamin
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supporting information; experimental part
p. 10765 - 10768
(2012/08/28)
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- Chiral phosphoric acid-catalyzed asymmetric oxidation of aryl alkyl sulfides and aldehyde-derived 1,3-dithianes: Using aqueous hydrogen peroxide as the terminal oxidant
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(R)-1,1'-Binaphthyl-2,2'-diol (R-BINOL) derived chiral phosphoric acids have been explored as organocatalysts for the asymmetric oxidation of a series of aryl alkyl sulfides and 1,3-dithianes derived from aldehydes with aqueous hydrogen peroxide (H2O2) as the terminal oxidant. The enantiomerically enriched sulfoxides are obtained in moderate to excellent yield (up to 99%) with excellent diastereoselectivity (up to >99:1 dr) and moderate to good enantioselectivity (up to 91:9 er). In particular, the present protocol stereoselectively provides an efficient access to enantiomerically enriched aryl alkyl sulfoxides and dithioacetal mono-sulfoxides, which strictly restrains the formation of the undesirable by-products: sulfones or disulfoxides. The tracking experiments also verify that this approach proceeds via a direct sulfoxidation process, instead of a kinetic resolution route by overoxidation of the resulting sulfoxides. Copyright
- Liu, Zhao-Min,Zhao, Hua,Li, Mei-Qiu,Lan, Yu-Bao,Yao, Qi-Bo,Tao, Jing-Chao,Wang, Xing-Wang
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supporting information; experimental part
p. 1012 - 1022
(2012/05/20)
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- Asymmetric counteranion-directed iron catalysis: A highly enantioselective sulfoxidation
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A highly active and enantioselective ion-pair sulfoxidation catalyst, consisting of an achiral iron(III)-salen cation and a chiral phosphate counteranion, mediates the oxidization of various sulfides with high yields and enantioselectivities. The enantioselectivities observed, especially for electron-poor substrates, represent the best results so far in manganese and iron-salen systems. This work represents the first application of our concept of asymmetric counteranion-directed catalysis (ACDC) to iron catalysis. Copyright
- Liao, Saihu,List, Benjamin
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supporting information
p. 2363 - 2367
(2012/10/30)
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- Titanium complexes of chiral amino alcohol derived Schiff bases as efficient catalysts in asymmetric oxidation of prochiral sulfides with hydrogen peroxide as an oxidant
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An efficient asymmetric oxidation of prochiral sulfides catalyzed by a series of simple in situ generated complexes based on chiral amino alcohol derived Schiff bases with Ti(Oi-Pr)4 was carried out in presence of cheap and environmentally benign oxidant H2O2 at 0 °C. Prochiral sulfides were converted to respective chiral sulfoxides efficiently (conversion, 93%; up to ee, 98%) with this system in 10 h at 0 °C. The present study demonstrated a significant role of steric influence of the substituent attached on both aryl and alkyl moiety on the enantioselectivity. Kinetic studies of the catalytic reaction showed first order dependence on substrate and catalyst whereas it is zero for the oxidant. Kinetic studies in combination with UV-vis. spectral studies were used to propose a catalytic cycle for the sulfoxidation reaction.
- Bera, Prasanta Kumar,Ghosh, Debashis,Abdi, Sayed Hasan Razi,Khan, Noor-Ul Hasan,Kureshy, Rukhsana Ilays,Bajaj, Hari Chandra
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experimental part
p. 36 - 44
(2012/08/07)
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- Exploring the biocatalytic scope of a bacterial flavin-containing monooxygenase
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A bacterial flavin-containing monooxygenase (FMO), fused to phosphite dehydrogenase, has been used to explore its biocatalytic potential. The bifunctional biocatalyst could be expressed in high amounts in Escherichia coli and was able to oxidize indole and indole derivatives into a variety of indigo compounds. The monooxygenase also performs the sulfoxidation of a wide range of prochiral sulfides, showing moderate to good enantioselectivities in forming chiral sulfoxides. The Royal Society of Chemistry 2011.
- Rioz-Martinez, Ana,Kopacz, Malgorzata,De Gonzalo, Gonzalo,Torres Pazmino, Daniel E.,Gotor, Vicente,Fraaije, Marco W.
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experimental part
p. 1337 - 1341
(2011/04/23)
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- First enantioselective iron-porphyrin-catalyzed sulfide oxidation with aqueous hydrogen peroxide
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The asymmetric oxidation of sulfides by H2O2 to give optically active sulfoxides (ee up to 90%) was carried out in methanol and water using chiral water-soluble iron porphyrins as catalysts.
- Le Maux, Paul,Simonneaux, Gerard
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supporting information; experimental part
p. 6957 - 6959
(2011/08/08)
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- New chiral molybdenum complex catalyzed sulfide oxidation with hydrogen peroxide
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Six new cis-dioxomolybdenum(VI) complexes of chiral Schiff-base ligands, derived from condensation of various amino alcohols and substituted salicylaldehydes, have been prepared and characterized by NMR, IR, ESI-MS and single crystal X-ray diffraction techniques. The geometry around the molybdenum center is distorted octahedral in which a tridentate Schiff-base ligand with two anionic oxygens and one neutral imine nitrogen occupies meridional position. The octahedral geometry of the cis-dioxomolybdenum center is additionally completed by a coordinated labile solvent molecule. In some complexes the sixth site is found to be vacant where the relatively bulky substituents hinder the coordination of the solvent. These complexes are tested for catalytic enantioselective sulfoxidation reactions using hydrogen peroxide as oxidant at low temperature which shows high selectivity along with good to moderate enantiomeric excess. ESI-MS study of the reaction mixture indicates the formation of oxoperoxoMo(VI) complexes during catalysis. The steric effect originated from the substituent on chiral ligand on the catalytic reaction is also discussed. It is found that the substituents at the β position of the amino alcohol seem to greatly influence the enantioselectivity of the oxidation reactions.
- Chakravarthy, Rajan Deepan,Suresh, Kotapati,Ramkumar, Venkatachalam,Chand, Dillip Kumar
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experimental part
p. 57 - 63
(2011/10/30)
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- Preparation of chiral oxovanadium (IV) Schiff base complex functionalized by ionic liquid for enantioselective oxidation of methyl aryl sulfides
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Chiral oxovanadium (IV) Schiff base complex covalently grafted with ionic liquid (IL: 1-(3-aminopropyl)-3-methylimidazolium tetrafluoroborate) has been reported first time. The IL-functionalized complex was found to be an efficient catalyst in the enantioselective oxidation of methyl aryl sulfides to sulfoxides with hydrogen peroxide as an oxidant. Especially, the IL-functionalized complex could be recovered conveniently by simple precipitation with addition of hexane and reused at least six cycles without loss of activity and enantioselectivity.
- Yin, Donghong,Tan, Rong,Li, Chengyong,Peng, Zhigang,Yin, Dulin
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experimental part
p. 1488 - 1491
(2012/07/27)
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- Synthesis and characterization of xanthene-bridged Schiff-base dimanganese(III) complexes: Bimetallic catalysts for asymmetric oxidation of sulfides
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Dimanganese(III) complexes of salen-type ligands anchored by 9,9-dimethylxanthene-4,5-diyl spacers were synthesized. Two types of structures, cyclic and acyclic forms, are presented. The 2+2 Schiff-base condensation of 5,5′-(9,9-dimethylxanthene-4,5-diyl)bis(salicylaldehyde) and 1,2-diaminobenzene gave a macrocyclic ligand, from which a cyclic dimanganese(III) complex was synthesized. A similar dimanganese(iii) complex with stereogenic centers was synthesized by the metal-assisted condensation reaction using (1R,2R)-1,2-diaminocyclohexane. Acyclic dimanganese(iii) complexes anchored by one xanthene spacer were obtained by metal-assisted stepwise condensation reactions using the xanthene-bridged bis(salicylaldehyde), (1R,2R)-1,2-diaminocyclohexane monohydrochloride, and salicylaldehydes. X-Ray crystal structure analysis confirmed that both cyclic and acyclic complexes have two cofacially oriented salen-type manganese(III) units in a complex cation, showing an Mn...Mn distance of ca. 5.1 A. Asymmetric oxidation of sulfides was performed by using the chiral dimeric complexes as catalysts, which showed enantiomeric excesses ranging from 5 to 19%. The addition of 4-(dimethylamino)pyridine to the reaction system improved the enantioselectivity up to 39% ee. This effect was not observed for the corresponding mononuclear catalyst. The Royal Society of Chemistry 2010.
- Hirotsu, Masakazu,Ohno, Naoki,Nakajima, Takashi,Kushibe, Chie,Ueno, Keiji,Kinoshita, Isamu
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experimental part
p. 139 - 148
(2010/03/03)
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- Synthesis of chiral sulfoxides by enantioselective sulfide oxidation and subsequent oxidative kinetic resolution using immobilized Ti-binol complex
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Chiral Ti-binol complex was immobilized onto ionic liquid modified SBA-15 and characterized by different physicochemical techniques. The catalyst was found to be highly enantioselective in the heterogeneous asymmetric oxidation of prochiral sulfides to sulfoxides and subsequent oxidative kinetic resolution of the sulfoxides using aqueous tert-butylhydroperoxide as the oxidant. A positive non-linear effect was observed in the oxidation-kinetic resolution of thioanisole using this supported catalyst. The supported catalyst was reused in multiple catalytic runs without any loss of enantioselectivity.
- Sahoo, Suman,Kumar, Pradeep,Lefebvre,Halligudi
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experimental part
p. 111 - 118
(2009/06/17)
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- Synthesis of optically active 2,5-dialkylcyclohexane-1,4-diols and their application in the asymmetric oxidation of sulfides
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A simple and efficient approach to obtain optically pure 1,4-diols was established. The asymmetric oxidation of sulfides to sulfoxides with cumyl hydroperoxide in moderate yields and moderate to high enantioselectivities (up to 84%) catalyzed by chiral Ti/ 1,4-diols complexes has been achieved. A 76% ee value was obtained in the asymmetric synthesis of esomeprazole. Georg Thieme Verlag Stuttgart.
- Sun, Jiangtao,Yang, Minghua,Dai, Zhenya,Zhu, Chengjian,Hu, Hongwen
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scheme or table
p. 2513 - 2518
(2009/04/11)
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- Highly enantioselective oxidation of sulfides to sulfoxides by a new oxaziridinium salt
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The new oxaziridinium salt 5 (R2 = TBDPS) is an effective reagent for the highly enantioselective oxidation of sulfides to sulfoxides with up to >99% ee and good yields. As such, it represents a new valuable nonmetallic alternative to the existing methods for asymmetric sulfoxidation.
- Del Rio,Wang,Achab,Bohe
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p. 2265 - 2268
(2008/02/04)
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- Iron-catalyzed oxidation of thioethers by iodosylarenes: Stereoselectivity and reaction mechanism
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Catalytic properties of a series of iron(III)-salen (salen = N,N′-bis(salicylidene)ethylenediamine dianion) and related complexes in asymmetric sulfoxidation reactions, with iodosylarenes as terminal oxidants, have been explored. These catalysts have been found to efficiently catalyze oxidation of alkyl aryl sulfides to sulfoxides with high chemoselectivity (up to 100%) and moderate-to-high enantioselectivity (up to 84% with isopropylthiobenzene and iodosylmesitylene), the TON (TON = turnover number) approaching 500. The influence of the ligand (electronic and steric effects of the substituents). oxidant, and substrate structures on the oxidation stereoselectivity has been investigated systematically. The structure of the reactive intermediates (complexes of the type [FeIII(ArIO)(salen)] and the reaction mechanism have been revealed by both mechanistic studies with different iodosylarenes and direct in situ 1H NMR observation of the formation of the reactive species and its reaction with the substrate.
- Bryliakov, Konstantin P.,Talsi, Evgenii P.
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p. 8045 - 8050
(2008/04/01)
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- Efficient soluble polymer-supported tartrate/Ti catalyst for asymmetric oxidation of prochiral sulfides
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A group of soluble polymer-supported chiral tartrate ligands was prepared by liquid-phase synthesis with ligand diversity strategy. Moderate to excellent chemical yields and enantiomeric excesses were obtained by using soluble polymer-supported tartrate ester in asymmetric oxidation of prochiral sulfides using Ti(O-i-Pr)4/cumyl hydroperoxide, and the workup was greatly simplified. The influence of substituent in chiral tartrate ligands on the enantioselectivities of the reaction was disclosed.
- Gao, Jinshan,Guo, Hongchao,Liu, Shangzhong,Wang, Min
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p. 8453 - 8455
(2008/03/13)
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- 4-Hydroxyacetophenone monooxygenase from Pseudomonas fluorescens ACB as an oxidative biocatalyst in the synthesis of optically active sulfoxides
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Recombinant 4-hydroxyacetophenone monooxygenase (HAPMO) from Pseudomonas fluorescens ACB has been tested as a catalyst in sulfoxidation reactions on a set of aromatic sulfides. With a few exceptions, excellent enantioselectivities in the synthesis of chiral phenyl and benzyl sulfoxides were achieved. The bacterial Baeyer-Villiger monooxygenase was also shown to accept racemic sulfoxides, a prochiral diketone and an organoboron compound as substrates. This study demonstrates the great biocatalytic potential of this novel oxidative enzyme.
- De Gonzalo, Gonzalo,Torres Pazmino, Daniel E.,Ottolina, Gianluca,Fraaije, Marco W.,Carrea, Giacomo
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p. 130 - 135
(2007/10/03)
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- Catalytic asymmetric oxidation of sulfide and styrene derivatives using macroporous resins containing chiral metalloporphyrins (Fe, Ru)
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Chiral metalloporphyrin (Fe, Ru) complexes, functionalized with four vinyl groups, have been polymerized with styrene and divinylbenzene (or ethylene glycol) to obtain supported iron and ruthenium complexes. The heterogeneous asymmetric oxidation of sulfides and styrene derivatives was carried out by using these polymers as catalysts. The reaction proceeded under mild conditions and gave sulfoxides and epoxides with good enantiomeric excesses (up to 75-76%). The catalysts keep constant ee values for the recycle tests of up to six times for asymmetric oxidation of styrene derivatives and of up to 14 times for asymmetric oxidation of sulfides with only traces of sulfones.
- Ferrand, Yann,Daviaud, Romain,Le Maux, Paul,Simonneaux, Gerard
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p. 952 - 960
(2007/10/03)
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- Oxidative kinetic resolution of alkyl aryl sulfoxides
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Kinetic resolution is observed in the oxidation of racemic alkyl aryl sulfoxides using a combination of VO(acac)2 and ligand 1 in chloroform at 0 °C, conditions previously described for asymmetric oxidation of prochiral sulfides. Kinetic resolution is also observed in toluene as the solvent, although higher temperatures are required. Georg Thieme Verlag Stuttgart.
- Mohammadpoor-Baltork, Iraj,Hill, Mathias,Caggiano, Lorenzo,Jackson, Richard F. W.
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p. 3540 - 3544
(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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- Self-supported heterogeneous titanium catalysts for enantioselective carbonyl-ene and sulfoxidation reactions
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A new strategy for the heterogenization of chiral titanium complexes was developed by the in situ assembly of bridged multitopic BINOL ligands with [Ti(OiPr)4] without using a support. The assembled heterogeneous catalysts (self-supported) show
- Wang, Xisheng,Wang, Xingwang,Guo, Hongchao,Wang, Zheng,Ding, Kuiling
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p. 4078 - 4088
(2007/10/03)
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- A re-investigation of Modena's protocol for the asymmetric oxidation of prochiral sulfides
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The reactivity of commercially available or easily accessible hydroperoxides has been conveniently exploited for the achievement of highly efficient and enantioselective catalytic modifications of Modena's protocol for the asymmetric oxidation of sulfides. A notably enhanced enantioselectivity has been obtained by exploiting a concomitant process of stereoconvergent kinetic resolution taking place under catalytic conditions.
- Massa, Antonio,Mazza, Valeria,Scettri, Arrigo
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p. 2271 - 2275
(2007/10/03)
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- Asymmetric sulfoxidation of thioethers with hydrogen peroxide in water mediated by platinum chiral catalyst
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Easy stereoselective oxidation of prochiral aryl alkyl sulfides 2 to the corresponding sulfoxides can be achieved in water-surfactant medium with inexpensive hydrogen peroxide mediated by the chiral platinum diphosphine complex {[(R)-BINAP]Pt(μ-OH)}2
- Scarso, Alessandro,Strukul, Giorgio
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p. 1227 - 1234
(2007/10/03)
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- Vanadium-catalyzed sulfur oxidation/kinetic resolution in the synthesis of enantiomerically pure alkyl aryl sulfoxides
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(Chemical Equation Presented) The importance of the mix: The use of chloroform as solvent, the ligand (R)-2 and [VO(acac)2] as catalyst, and H2O2 as oxidant promotes the highly enantioselective oxidation of simple alkyl aryl sulfides 1 to give alkyl aryl sulfoxides (R)-3 (see scheme). The success of this process partly derives from an efficient kinetic resolution of the product sulfoxides.
- Drago, Carmelo,Caggiano, Lorenzo,Jackson, Richard F. W.
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p. 7221 - 7223
(2007/10/03)
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- Investigations on the iron-catalyzed asymmetric sulfide oxidation
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The development of an enantioselective sulfide oxidation involving a chiral iron catalyst and aqueous hydrogen peroxide as oxidant is described. In the presence of a simple carboxylic acid, or a carboxylate salt, the reaction affords sulfoxides with remarkable enantioselectivities (up to 96% ee) in moderate to good yields. The influence of the structure of the additive on the reaction outcome is reported. In the sulfoxide-to-sulfone oxidation a kinetic resolution (with s = 4.8) occurs, which, however, plays only a negligible role in the overall enantioselective process. Furthermore, a positive nonlinear relationship between the ee of the product and that of the catalyst has been found. On the basis of these observations, a possible catalyst structure is proposed.
- Legros, Julien,Bolm, Carsten
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p. 1086 - 1092
(2007/10/03)
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- Enantioselective oxidation of sulfides with hydrogen peroxide catalyzed by vanadium complex of sterically hindered chiral Schiff bases
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Sterically hindered chiral Schiff base ligands 4a-d were prepared from an aldehyde derived from BINOL. The vanadium complexes of the ligands catalyze an efficient, enantioselective H2O2-promoted sulfoxidation of alkyl aryl sulfides, and enantioselectivities as high as 98-99% ee are observed in the sulfoxidation of benzyl aryl sulfides.
- Jeong, Yong-Chul,Choi, Soojin,Hwang, Yao Dong,Ahn, Kwang-Hyun
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p. 9249 - 9252
(2007/10/03)
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- Highly enantioselective iron-catalyzed sulfide oxidation with aqueous hydrogen peroxide under simple reaction conditions
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An attractive alternative to the currently existing methods for the metal-catalyzed oxidation of sulfides to sulfoxides is asymmetric iron-catalyzed oxidation with hydrogen peroxide as the terminal oxidant (see scheme). In the presence of a benzoic acid derivative, this simple process provides sulfoxides with up to 96% ee in moderate to good yields (up to 78%).
- Legros, Julien,Bolm, Carsten
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p. 4225 - 4228
(2007/10/03)
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- Nb(salen)-catalyzed sulfoxidation
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Niobium(salen) complex was found to be an effective catalyst for asymmetric oxidation of various sulfides using urea-hydrogen peroxide as terminal oxidant.
- Miyazaki, Takanori,Katsuki, Tsutomu
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p. 1046 - 1048
(2007/10/03)
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- Iron-Catalyzed Asymmetric Sulfide Oxidation with Aqueous Hydrogen Peroxide
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An iron in the fire: Iron-based catalysts promote the asymmetric oxidation of alkyl aryl sulfides to the corresponding sulfoxides with up to 90% ee (see scheme). Simple hydrogen peroxide (30% in water) serves as the terminal oxidant.
- Legros, Julien,Bolm, Carsten
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p. 5487 - 5489
(2007/10/03)
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- Vanadium-catalyzed enantioselective sulfoxidation of methyl aryl sulfides with hydrogen peroxide as terminal oxidant
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Chiral vanadium complex prepared in situ from VO(acac)2 and Schiff base 9 was found to be an efficient catalyst for oxidation of various methyl aryl sulfides with hydrogen peroxide as terminal oxidant. For example, oxidation of methyl 2-naphthyl sulfide using a VO(acac)2, 9, and hydrogen peroxide system proceeded with high enantioselectivity of 93% ee as well as acceptable chemical yield.
- Ohta,Shimizu,Kondo,Katsuki
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p. 161 - 163
(2007/10/03)
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