- 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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- Two enantiocomplementary Baeyer-Villiger monooxygenases newly identified for asymmetric oxyfunctionalization of thioether
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Two enantiocomplementary Baeyer-Villiger monooxygenases RaBVMO and AmBVMO were identified by genome mining for the asymmetric sulfoxidation. Both recombinant BVMOs have optimal pH of 9.0 and temperature of 35 °C. The half-lives of RaBVMO and AmBVMO at 30 °C were 24.4 and 24.6 h. RaBVMO and AmBVMO exhibited broad substrate spectrum and could catalyze the oxidization of various compounds including fatty ketones, cyclic ketones, and thioethers. Kinetic parameters analysis revealed that both RaBVMO and AmBVMO displayed higher catalytic efficiency toward thioanisole than cyclohexanone. As much as 50 mM thioanisole could be completely oxidized by AmBVMO and RaBVMO with 99% (R) and 95% (S), respectively. Molecular docking analysis further provides evidence for the complementary enantioselectivity of RaBVMO and AmBVMO. Our results demonstrate the potential application of the two novel BVMOs in asymmetric synthesis of sulfoxides.
- Liu, Yafei,Ni, Ye,Wei, Shiyu,Xu, Guochao,Zhou, Jieyu
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- Stereoselective sulfoxidation catalyzed by achiral Schiff base complexes in the presence of serum albumin in aqueous media
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Four coordination complexes ML derived from an achiral Schiff base ligand (H2L = 2,2′-[(1,2-ethanediyl)bis(nitrilopropylidyne)]bisphenol) have been synthesized and characterized. A method is described for the enantioselective oxidation of a series of aryl alkyl sulfides using the coordination complexes in the presence of serum albumins (SAs) in an aqueous medium at ambient temperature. The mixture of metal complexes with serum albumins is useful for inducing asymmetric catalysis. The complex, albumin source and substrate influence stereoselective sulfoxidation. At optimal pH with the appropriate oxidant, some of ML/SA systems are identified as very efficient catalysts, giving the corresponding sulfoxides in excellent chemical yield (up to 100%) and good enantioselectivity (up to 94% ee) in certain cases. UV–visible spectroscopic data provide evidence that stronger binding between the complex and serum albumin lead to higher enantioselectivity.
- Tang, Jie,Yao, Pengfei,Huang, Fuping,Luo, Meiyi,Wei, Yi,Bian, Hedong
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supporting information
p. 1700 - 1707
(2017/11/17)
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- Asymmetric catalytic sulfoxidation by a novel v IV 8 cluster catalyst in the presence of serum albumin: A simple and green oxidation system
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A novel VIV8 cluster formulated as [V8O12(OH)4(CH3O)4(DAC)4]·7CH3OH (1) (DAC = 1,2-diaminocyclohexane) has been constructed successfully. Enantioselective oxidation of a series of alkyl aryl sulfides catalyzed by 1 is tested in an aqueous medium in the presence of serum albumin. The catalytic procedure is found to be simple and environmentally friendly. The influences of the parameters such as concentration of catalyst and oxidant, pH, and reaction time on the thioanisole as models are investigated. Under optimum conditions, 1 exhibits high conversion (up to 99%), excellent chemoselectivity (≥90% in all cases) and moderate enantioselectivity (up to 75% ee). After binding with serum albumin, the catalytic activity of 1 is promoted. The bovine serum albumin (BSA) and pig serum albumin (PSA) molecules have a more positive effect on the catalytic activity.
- Tang, Jie,Yao, Peng-Fei,Xu, Xiao-Ling,Li, Hai-Ye,Huang, Fu-Ping,Nie, Qing-Qing,Luo, Mei-Yi,Yu, Qing,Bian, He-Dong
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p. 44154 - 44162
(2016/06/09)
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- Development of a Continuous-Flow Microreactor for Asymmetric Sulfoxidation Using a Biomimetic Manganese Catalyst
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Asymmetric sulfoxidation catalyzed by a biomimetic manganese complex under continuous-flow microreactor is described. The reaction is conducted in microreactor, it can rapidly (4 min) oxidize a wide scope of sulfides with high yield (up to 91%) and excel
- Dai, Wen,Mi, Yuan,Lv, Ying,Chen, Bo,Li, Guosong,Chen, Guangwen,Gao, Shuang
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p. 667 - 671
(2016/02/27)
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- Method for preparing chiral sulfoxide through catalysis of asymmetric oxidation of thioether
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The invention provides a method for preparing chiral sulfoxide. According to the method, in a mixed solvent, thioether is used as a substrate, a complex produced by chiral tetradentate organic ligand and a metal manganese compound in situ is used as a cat
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Paragraph 0058; 0059; 0060; 0061; 0062
(2016/10/10)
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- Bovine serum albumin-cobalt(II) Schiff base complex hybrid: An efficient artificial metalloenzyme for enantioselective sulfoxidation using hydrogen peroxide
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An artificial metalloenzyme (BSA-CoL) based on the incorporation of a cobalt(ii) Schiff base complex {CoL, H2L = 2,2′-[(1,2-ethanediyl)bis(nitrilopropylidyne)]bisphenol} with bovine serum albumin (BSA) has been synthesized and characterized. Attention is focused on the catalytic activity of this artificial metalloenzyme for enantioselective oxidation of a variety of sulfides with H2O2. The influences of parameters such as pH, temperature, and the concentration of catalyst and oxidant on thioanisole as a model are investigated. Under optimum conditions, BSA-CoL as a hybrid biocatalyst is efficient for the enantioselective oxidation of a series of sulfides, producing the corresponding sulfoxides with excellent conversion (up to 100%), chemoselectivity (up to 100%) and good enantiomeric purity (up to 87% ee) in certain cases.
- Tang, Jie,Huang, Fuping,Wei, Yi,Bian, Hedong,Zhang, Wei,Liang, Hong
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p. 8061 - 8072
(2016/06/06)
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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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- 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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- Enantioselective oxidation of sulfides with H2O2 catalyzed by a pre-formed manganese complex
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A facile and environmentally friendly method is presented for the asymmetric oxidation of sulfides with H2O2, utilizing a pre-formed manganese complex. Just in the presence of a low catalytic amount of carboxylic acid (CA), a variety of sulfide substrates, including aryl alkyl, aryl benzyl and cyclic sulfides, reacted to form chiral sulfoxides in high yields (up to 95%) and excellent enantioselectivities (>99% ee) under mild conditions. Moreover, the practical utility of the method has been demonstrated by the synthesis of esomeprazole and albendazole sulfoxide (ABZO).
- Dai, Wen,Li, Guosong,Wang, Lianyue,Chen, Bo,Shang, Sensen,Lv, Ying,Gao, Shuang
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p. 46545 - 46554
(2014/12/10)
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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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- 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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- Albumin-conjugated corrole metal complexes: Extremely simple yet very efficient biomimetic oxidation systems
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An extremely simple biomimetic oxidation system, consisting of mixing metal complexes of amphiphilic corroies with serum albumins, utilizes hydrogen peroxide for asymmetric sulfoxidation in up to 74% ee. The albumin-conjugated manganese corroies also disp
- Mahammed, Atif,Gross, Zeev
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p. 2883 - 2887
(2007/10/03)
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- Efficient asymmetric oxidation of sulfides and kinetic resolution of sulfoxides catalyzed by a vanadium-salan system
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The asymmetric oxidation of sulfides to chiral sulfoxides with hydrogen peroxide in good yield and high enantioselectivity has been catalyzed very effectively by chiral vanadium-salan [N,N′-alkyl bis(salicylamine)] complex. The salan ligand shows results superior in terms of reactivity and enantioselectivity to those of salen [N,N′-alkylene bis(salicylideneimine) ] analogue, and provides the sulfoxide with opposite configuration. The high enantioselectivity of this reaction is the direct result of the asymmetric oxidation. The efficient kinetic resolution of racemic sulfoxides catalyzed by the vanadium-salan system is also described.
- Sun, Jiangtao,Zhu, Chengjian,Dai, Zhenya,Yang, Minghua,Pan, Yi,Hu, Hongwen
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p. 8500 - 8503
(2007/10/03)
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- Chiral ionic liquids as stationary phases in gas chromatography
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Recently, it has been found that room-temperature ionic liquids can be used as stable, unusual selectivity stationary phases. They show "dual nature" properties, in that they separate nonpolar compounds as if they are nonpolar stationary phases and separate polar compounds as if they are polar stationary phases. Extending ionic liquids to the realm of chiral separations can be done in two ways: (1) a chiral selector can be dissolved in an achiral ionic liquid, or (2) the ionic liquid itself can be chiral. There is a single precedent for the first approach, but nothing has been reported for the second approach. In this work, we present the first enantiomeric separations using chiral ionic liquid stationary phases in gas chromatography. Compounds that have been separated using these ionic liquid chiral selectors include alcohols, diols, sulfoxides, epoxides, and acetylated amines. Because of the synthetic nature of these chiral selectors, the configuration of the stereogenic center can be controlled and altered for mechanistic studies and reversing enantiomeric retention.
- Ding, Jie,Welton, Thomas,Armstrong, Daniel W.
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p. 6819 - 6822
(2007/10/03)
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