- Visible-light assisted of nano Ni/g-C3N4 with efficient photocatalytic activity and stability for selective aerobic C?H activation and epoxidation
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A selective, economical, and ecological protocol has been described for the oxidation of methyl arenes and their analogs to the corresponding carbonyl compounds and epoxidation reactions of alkenes with molecular oxygen (O2) or air as a green oxygen source, under mild reaction conditions. The nano Ni/g-C3N4 exhibited high photocatalytic activity, stability, and selectivity in the C?H activation of methyl arenes, methylene arenes, and epoxidation of various alkenes under visible- light irradiation without the use of an oxidizing agent and under base free conditions.
- Akrami, Zahra,Hosseini-Sarvari, Mona
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supporting information
(2020/10/13)
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- Synthesis, Characterization, and Application of Oxo-Molybdenum(V)-Corrolato Complexes in Epoxidation Reactions
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Sharpless et al. have described, while performing the molybdenum-catalyzed epoxidation reaction of olefins using alkyl hydroperoxides, that the molybdenum-oxo moiety is an active catalytic species. Thus, continuous efforts have been made to synthesize molybdenum-oxo complexes of different ligand environments. While plenty of such works on molybdenum porphyrins are reported in the literature, related molybdenum corroles are very less reported. The synthesis and characterization of two new oxo-molybdenum(V)-corrolato complexes are described herein. Both the complexes have been fully characterized by several spectroscopic techniques in conjunction with single-crystal X-ray diffraction analysis. The efficacy of the oxo-molybdenum(V)-corrolato complexes for the catalytic epoxidation reaction of olefins with the help of hydroperoxides has also been explored. The catalytic application of oxo-molybdenum(V)-corrolato complexes in the epoxidation reaction has not been reported earlier. A mechanism has been proposed to explain the experimental findings.
- Nayak, Manisha,Nayak, Panisha,Sahu, Kasturi,Kar, Sanjib
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supporting information
p. 11654 - 11662
(2020/10/23)
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- Thiourea composite feed additive with urease inhibition activity and preparation method thereof
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The invention discloses a thiourea composite feed additive with urease inhibition activity and a preparation method thereof, and belongs to the technical field of synthesis of feed additives. The technical scheme is characterized in that the compound structure of the thiourea composite feed additives is shown in the description. Compared with the prior art, the thiourea composite feed additive hasthe following beneficial effects: 1, the non-protein nitrogen group and the nitrogen-containing micromolecule urease inhibitor group can be linked together through the hydrophilic group by the feed additive obtained by the method, meanwhile, functions of supplementing non-protein nitrogen and inhibiting urease are provided; 2, the tandem non-protein nitrogen group and the nitrogen-containing small molecule urease inhibitor group are completed by 2-hydroxy propane through oxygen and imino, which is an excellent hydrophilic group, has good water solubility, has a stable molecular structure in vitro, and can effectively release a non-protein nitrogen group and a nitrogen-containing micromolecule urease inhibitor group in gastric juice; 3, the feed additive has no toxic or side effect; 4, themethod has simple operation and high product yield.
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Paragraph 0023-0037
(2019/04/29)
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- Exploring the Biocatalytic Scope of a Novel Enantioselective Halohydrin Dehalogenase from an Alphaproteobacterium
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A gene encoding halohydrin dehalogenase from an alphaproteobacterium (AbHHDH) was identified, cloned and over-expressed in Escherichia coli. AbHHDH was able to catalyze the stereoselective dehalogenation of prochiral and racemic halohydrins. It showed the highest enantioselectivity in the dehalogenation of 20?mM (R,S)-2-bromo-1-phenylethanol, which yielded (S)-2-bromo-1-phenylethanol with 99% ee and 34.5% yield. Moreover, AbHHDH catalyzed the azidolysis of epoxides with low to moderate (S)-enantioselectivity. The highest enantioselectivity (E = 18.6) was observed when (R,S)-benzyl glycidyl ether was used as the substrate. A sequential kinetic resolution catalyzed by HHDH was employed for the synthesis of chiral 1-chloro-3-phenoxy-2-propanol. We prepared enantiopure (S)-isomer with a high enantiopurity of ee > 99% and a yield of 30.7% (E-value: 21.3) by kinetic resolution of 20?mM substrate. The (S)-isomer with 99% ee readily obtained from 40 to 150?mM (R,S)-1-chloro-3-phenoxy-2-propanol. Taken together, the results of this study demonstrate the applicability of this HHDH for the production of optically active compounds. [Figure not available: see fulltext.].
- Xue, Feng,Ya, Xiangju,Xiu, Yuansong,Tong, Qi,Wang, Yuqi,Zhu, Xinhai,Huang, He
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p. 629 - 637
(2019/01/25)
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- Homochiral Metal-Organic Cage for Gas Chromatographic Separations
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Metal-organic cages (MOCs) as a new type of porous material with well-defined cavities were extensively pursued because of their relative ease of synthesis and their potential applications in host-guest chemistry, molecular recognition, separation, catalysis, gas storage, and drug delivery. Here, we first reported that a homochiral MOC [Zn3L2] is explored to fabricate [Zn3L2] coated capillary column for high-resolution gas chromatographic separation of a wide range of analytes, including n-alkanes, polycyclic aromatic hydrocarbons, and positional isomers, especially for racemates. Various kinds of racemates such as alcohols, diols, epoxides, ethers, halohydrocarbons, and esters were separated with good enantioselectivity and reproducibility on the [Zn3L2] coated capillary column. The fabricated [Zn3L2] coated capillary column exhibited significant chiral recognition complementary to that of a commercial β-DEX 120 column and our recently reported homochiral porous organic cage CC3-R coated column. The results show that the homochiral MOCs will be very attractive as a new type of chiral selector in separation science.
- Xie, Sheng-Ming,Fu, Nan,Li, Li,Yuan, Bao-Yan,Zhang, Jun-Hui,Li, Yan-Xia,Yuan, Li-Ming
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p. 9182 - 9188
(2018/07/21)
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- Discovery of novel small molecule TLR4 inhibitors as potent anti-inflammatory agents
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Toll-like receptor 4 (TLR4) initiates innate immune response to release inflammatory cytokines and has been pathologically linked to variety of inflammatory diseases. Recently, we found that Carvedilol, as the classic anti-heart failure and anti-inflammatory clinic drug, could inhibit the TLR4 signaling in the TLR4 overexpressed cells. Herein, we have designed and synthesized a small library of novel Carvedilol derivatives and investigated their potential inhibitory activity. The results indicate that the most potent compound 8a (SMU-XY3) could effectively inhibited TLR4 protein and the LPS triggered alkaline phosphatase signaling in HEK-Blue hTLR4 cells. It down regulated the nitric oxide (NO) in both RAW264.7 cells and BV-2 microglial cells, in addition to blocking the TNF-α signaling in ex-vivo human peripheral blood mononuclear cells (PBMC). More interestingly, 8a shows higher affinity to hyperpolarization-activated cyclic nucleotide-gated 4 (HCN4) over HCN2, which probably indicates the new application of TLR4 inhibitor 8a in heart failure, coronary heart disease, and other inflammatory diseases.
- Xu, Yao,Chen, Shujun,Cao, Ying,Zhou, Pingzheng,Chen, Zhipeng,Cheng, Kui
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p. 253 - 266
(2018/05/29)
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- Application of homochiral alkylated organic cages as chiral stationary phases for molecular separations by capillary gas chromatography
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Molecular organic cage compounds have attracted considerable attention due to their potential applications in gas storage, catalysis, chemical sensing, molecular separations, etc. In this study, a homochiral pentyl cage compound was synthesized from a condensation reaction of (S,S)-1,2-pentyl-1,2-diaminoethane and 1,3,5-triformylbenzene. The imine-linked pentyl cage diluted with a polysiloxane (OV-1701) was explored as a novel stationary phase for high-resolution gas chromatographic separation of organic compounds. Some positional isomers were baseline separated on the pentyl cage-coated capillary column. In particular, various types of enantiomers including chiral alcohols, esters, ethers and epoxides can be resolved without derivatization on the pentyl cage-coated capillary column. The reproducibility of the pentyl cage-coated capillary column for separation was investigated using nitrochlorobenzene and styrene oxide as analytes. The results indicate that the column has good stability and separation reproducibility after being repeatedly used. This work demonstrates that molecular organic cage compounds could become a novel class of chiral separation media in the near future.
- Xie, Shengming,Zhang, Junhui,Fu, Nan,Wang, Bangjin,Hu, Cong,Yuan, Liming
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- Manganese(II)/Picolinic Acid Catalyst System for Epoxidation of Olefins
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An in situ generated catalyst system based on Mn(CF3SO3)2, picolinic acid, and peracetic acid converts an extensive scope of olefins to their epoxides at 0 °C in 5 min, with remarkable oxidant efficiency and no evidence of radical behavior. Competition experiments indicate an electrophilic active oxidant, proposed to be a high-valent Mn = O species. Ligand exploration suggests a general ligand sphere motif contributes to effective oxidation. The method is underscored by its simplicity and use of inexpensive reagents to quickly access high value-added products.
- Moretti, Ross A.,Du Bois,Stack, T. Daniel P.
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supporting information
p. 2528 - 2531
(2016/07/06)
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- Synthetic method of tamoxifen medicine intermediate epibromohydrin
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A synthetic method of a tamoxifen medicine intermediate epibromohydrin includes the following steps: 1) adding 5.6 mol of 1-amino-3-bromo-propyl alcohol, 6.1-6.3 mol of a 2-bromophenol solution, 800 ml of a potassium bromide solution, 2.56 mol of aluminum oxide, 700 ml of hexane and 300 ml of a sodium sulfite solution into a reaction container provided with a distilling apparatus; 2) increasing the solution temperature to 70-75 DEG C and performing a reaction for 3-5 h, reducing the solution temperature to 50-55 DEG C, controlling the stirring rate to be 110-150 rpm, performing reflux for 90-110 min, and reducing the solution temperature to 10-13 DEG C, and allowing the solution to stand for 2-5 h to layer the solution; and 3) washing an oil layer successively with a salt solution, acetonitrile and isopropyl alcohol, performing pressure-reduced distillation and collecting the fraction at 80-85 DEG C, and performing re-crystallization in nitromethane to obtain the epibromohydrin crystal.
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-
Paragraph 0007; 0015; 0016
(2016/11/24)
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- METHOD FOR PURIFYING 2-FLUOROBUTANE
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The present invention is a method for 2-fluorobutane to obtain highly purified 2-fluorobutane through a process comprising a step for: bringing crude 2-fluorobutane that includes 5 to 50 wt % of butene into contact with a brominating agent that can form a bromonium ion in an aprotic polar solvent in the presence of water or an alcohol having up to 4 carbon atoms; converting the butene into compounds having a boiling point higher than that of 2-fluorobutane, then recovering 2-fluorbutane from the reaction solution; and purifying the recovered 2-fluorabutane by distillation.
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Paragraph 0048
(2016/06/13)
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- Synthesis of ethyl (R)-4-cyano-3-hydroxybutyrate in high concentration using a novel halohydrin dehalogenase HHDH-PL from Parvibaculum lavamentivorans DS-1
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We identified and characterized a novel halohydrin dehalogenase HHDH-PL from Parvibaculum lavamentivorans DS-1. Study of substrate specificity indicated that HHDH-PL possessed a high activity toward ethyl (S)-4-chloro-3-hydroxybutanoate ((S)-CHBE). After optimizations of the pH and temperature, whole cell catalysis of HHDH-PL was applied to the synthesis of ethyl (R)-4-cyano-3-hydroxybutyrate (HN) at 200 g L-1 of (S)-CHBE, which gave 95% conversion and 85% yield in 14 h.
- Wan, Nan-Wei,Liu, Zhi-Qiang,Huang, Kai,Shen, Zhen-Yang,Xue, Feng,Zheng, Yu-Guo,Shen, Yin-Chu
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p. 64027 - 64031
(2015/02/19)
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- Heterobimetallic dual-catalyst systems for the hydrolytic kinetic resolution of terminal epoxides
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A heterobimetallic dual-catalyst system based on the preparation and use of various salen complexes has been developed for the hydrolytic kinetic resolution (HKR) of terminal epoxides. A combination of cobalt-salen and manganese-salen complexes, generated from ligands with the same configuration possessing thiophene or pyrrole moieties, produced indeed highly selective catalysts for the hydrolysis of epibromohydrin. This effect could also be extended to other terminal epoxides and to the more challenging ring opening of cyclohexene oxide. Kinetic studies indicated that only one CoIII salen complex was involved in the rate-determining step, which supported a heterobimetallic highly enantioselective pathway based on the crucial existence of in situ generated CoIII-OH species, previously postulated in the literature. The beneficial effect of the presence of additional Mn-complexes was ascribed to the inhibition of the alternative less enantioselective monometallic reaction pathway by epoxide activation.
- Hong, Xiang,Mellah, Mohamed,Schulz, Emmanuelle
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p. 2608 - 2617
(2014/07/22)
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- Biocatalytic and Structural Properties of a Highly Engineered Halohydrin Dehalogenase
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Two highly engineered halohydrin dehalogenase variants were characterized in terms of their performance in dehalogenation and epoxide cyanolysis reactions. Both enzyme variants outperformed the wild-type enzyme in the cyanolysis of ethyl (S)-3,4-epoxybutyrate, a conversion yielding ethyl (R)-4-cyano-3-hydroxybutyrate, an important chiral building block for statin synthesis. One of the enzyme variants, HheC2360, displayed catalytic rates for this cyanolysis reaction enhanced up to tenfold. Furthermore, the enantioselectivity of this variant was the opposite of that of the wild-type enzyme, both for dehalogenation and for cyanolysis reactions. The 37-fold mutant HheC2360 showed an increase in thermal stability of 8°C relative to the wild-type enzyme. Crystal structures of this enzyme were elucidated with chloride and ethyl (S)-3,4-epoxybutyrate or with ethyl (R)-4-cyano-3-hydroxybutyrate bound in the active site. The observed increase in temperature stability was explained in terms of a substantial increase in buried surface area relative to the wild-type HheC, together with enhanced interfacial interactions between the subunits that form the tetramer. The structures also revealed that the substrate binding pocket was modified both by substitutions and by backbone movements in loops surrounding the active site. The observed changes in the mutant structures are partly governed by coupled mutations, some of which are necessary to remove steric clashes or to allow backbone movements to occur. The importance of interactions between substitutions suggests that efficient directed evolution strategies should allow for compensating and synergistic mutations during library design.
- Schallmey, Marcus,Floor, Robert J.,Hauer, Bernhard,Breuer, Michael,Jekel, Peter A.,Wijma, Hein J.,Dijkstra, Bauke W.,Janssen, Dick B.
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p. 870 - 881
(2013/07/25)
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- USES OF FORMULATIONS OF THYROID HORMONE ANALOGS AND NANOPARTICULATE FORMS THEREOF TO INCREASE CHEMOSENSIVITY AND RADIOSENSITIVITY IN TUMOR OR CANCER CELLS
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Disclosed are methods of increasing the chemosensitivity of normal and/or chemoresistant tumor or cancer cells using thyroid hormone analogs and/or nanoparticulate or polymeric forms thereof. Also disclosed are methods of increasing radiosensitivity of normal and/or radioresistant tumor or cancer cells using thyroid hormone analogs and/or nanoparticulate or polymeric forms thereof.
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- Enantioselectivity of haloalkane dehalogenases and its modulation by surface loop engineering
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In the loop: Engineering of the surface loop in haloalkane dehalogenases affects their enantiodiscrimination behavior. The temperature dependence of the enantioselectivity (lnE versus 1/T) of β-bromoalkanes by haloalkane dehalogenases is reversed (red data points) by deletion of the surface loop; the selectivity switches back when an additional single-point mutation is made. This behavior is not observed for -bromoesters.
- Prokop, Zbynek,Sato, Yukari,Brezovsky, Jan,Mozga, Tomas,Chaloupkova, Radka,Koudelakova, Tana,Jerabek, Petr,Stepankova, Veronika,Natsume, Ryo,Van Leeuwen, Jan G. E.,Janssen, Dick B.,Florian, Jan,Nagata, Yuji,Senda, Toshiya,Damborsky, Jiri
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supporting information; experimental part
p. 6111 - 6115
(2010/11/05)
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- Reactions of chloromethyloxirane and dihalopropanols with chalcogens in basic reducing systems
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Chloromethyloxirane and 2,3-dibromopropan-1-ol reacted with a solution of selenium or tellurium in the system hydrazin hydrate-potassium hydroxide (K 2Se2, K2Te2) to give allyl alcohol; the reaction was accompanied by regeneration of the initial free chalcogen. 1,3-Dichloropropan-2-ol reacted with selenium in the same system to give oligomeric product having a 2-hydroxypropane-1,3-diyldiseleno monomeric unit, while the reaction with tellurium led to the formation of allyl alcohol and almost complete regeneration of initial tellurium. Probable reaction mechanisms are discussed. Polyselenide oligomers containing a hydroxy group in a monomeric unit were formed in reactions of chloromethyloxirane and 1,3-dichloropropan-2-ol with selenium in the system hydrazine hydrate-2-aminoethanol. Under analogous conditions 2,3-dibromopropan-1-ol was converted into allyl alcohol with regeneration of elemental selenium. Reductive cleavage of polyselenide oligomers gave Se-methyl derivatives of 2-hydroxypropane-1,3-diselenol.
- Elaev,Grabel'nykh,Russavskaya,Levanova,Sukhomazova,Zhanchipova,Klyba,Albanov,Korchevin
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body text
p. 505 - 510
(2009/04/11)
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- Epoxidation and oxidation reactions using divinyl benzene crosslinked polystyrene supported t-butyl hydroperoxide
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Divinyl benzene (DVB) crosslinked polystyrene supported t-butyl hydroperoxide resin has been prepared and employed in the epoxidation of olefins and oxidation of alcohols. The reagent is found to be efficient as the low molecular weight t-butyl hydroperoxide. Presence of catalyst enhanced the reaction efficiency remarkably. Influence of various reaction parameters such as solvent, temperature and molar excess of the reagent on the reactivity of the polymeric reagent is also being investigated.
- Sheela,Sreekumar
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p. 943 - 950
(2007/10/03)
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- Catalytic epoxidation of olefins in the presence of a vanadyl porphyrin complex
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It was found that vanadyl porphyrin complexes synthesized from petroleum metal porphyrin concentrates stimulated epoxidation during the olefin oxygenation process. The yields of obtained oxiranes turned out to be 38-75%, depending on the olefin structure. An epoxidation mechanism that suggests the formation of a protonated dioxygen adduct as an intermediate during oxygenation of olefins in the presence of vanadyl porphyrin complexes was proposed. An analogy is drawn between the epoxide formation reaction upon the catalytic oxygenation of olefins and the Prilezhaev reaction. MAIK "Nauka/Interperiodica".
- Miralamov,Mamedov
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- Enzymatic dynamic kinetic resolution of epihalohydrins
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The haloalcohol dehalogenase from Agrobacterium radiobacter AD1 catalyses the reversible ring closure of vicinal haloalcohols to produce epoxides and halides. In the ring opening of epoxides, nonhalide nucleophiles such as N 3- are accepted. The enantioselective irreversible ring opening of an epihalohydrin by N3-, combined with racemisation caused by a reversible ring opening by a halide, resulted in an enzymatic dynamic kinetic resolution yielding optically active (S)-1-azido-3-halo-2-propanol. With epichlorohydrin as a substrate, the rate of ring opening by N3- was higher than the rate of racemisation, resulting in a mixed kinetic resolution and dynamic kinetic resolution. With epibromohydrin as the substrate, the racemisation rate was higher than the rate of ring opening, resulting in an efficient dynamic kinetic resolution. By optimising the pH of the medium and the concentrations of N 3- and Br-, the product (S)-1-azido-3-bromo-2- propanol could be obtained in 84% yield and 94% ee. An (R)-enantiomer selective ring closure of this bromoalcohol, catalysed by the same enzyme, caused a simultaneously occurring kinetic resolution, yielding when the conversion progressed, an increase in enantiopurity of (S)-1-azido-3-bromo-2-propanol to >99% ee with a yield of 77%. This compound and the ring-closed product glycidyl azide can be used as chiral synthetic building blocks.
- Lutje Spelberg, Jeffrey H.,Tang, Lixia,Kellogg, Richard M.,Janssen, Dick B.
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p. 1095 - 1102
(2007/10/03)
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- Highly selective hydrolytic kinetic resolution of terminal epoxides catalyzed by chiral (salen)CoIII complexes. Practical synthesis of enantioenriched terminal epoxides and 1,2-diols
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The hydrolytic kinetic resolution (HKR) of terminal epoxides catalyzed by chiral (salen)CoIII complex 1·OAc affords both recovered unreacted epoxide and 1,2-diol product in highly enantioenriched form. As such, the HKR provides general access to useful, highly enantioenriched chiral building blocks that are otherwise difficult to access, from inexpensive racemic materials. The reaction has several appealing features from a practical standpoint, including the use of H2O as a reactant and low loadings (0.2-2.0 mol %) of a recyclable, commercially available catalyst. In addition, the HKR displays extraordinary scope, as a wide assortment of sterically and electronically varied epoxides can be resolved to ≥ 99% ee. The corresponding 1,2-diols were produced in good-to-high enantiomeric excess using 0.45 equiv of H2O. Useful and general protocols are provided for the isolation of highly enantioenriched epoxides and diols, as well as for catalyst recovery and recycling. Selectivity factors (krel) were determined for the HKR reactions by measuring the product ee at ca. 20% conversion. In nearly all cases, krel values for the HKR exceed 50, and in several cases are well in excess of 200.
- Schaus, Scott E.,Brandes, Bridget D.,Larrow, Jay F.,Tokunaga, Makoto,Hansen, Karl B.,Gould, Alexandra E.,Furrow, Michael E.,Jacobsen, Eric N.
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p. 1307 - 1315
(2007/10/03)
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- Crystallization-induced asymmetric transformations. Enantiomerically pure (-)-(R)- and (+)-(S)-2,3-dibromopropan-1-ol and epibromohydrins. A study of dynamic resolution via the formation of diastereoisomeric esters
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(S)-2,3-Dibromopropan-1-ol of high enantiomer excess was obtained by crystallization-induced asymmetric transformations of racemic 2,3-dibromopropan-1-ol esterified with N-([1,1′-biphenyl]-4-ylcarbonyl-L-alanine; in particular, an asymmetric transformatio
- Brunetto, Gabriella,Gori, Susanna,Fiaschi, Rita,Napolitano, Elio
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p. 3785 - 3791
(2007/10/03)
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- Highly selective epoxidation of olefinic compounds over TS-1 and TS-2 redox molecular sieves using anhydrous urea-hydrogen peroxide as oxidizing agent
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Highly selective epoxidation of different olefinic compounds was carried out using urea-hydrogen peroxide adduct (UHP) as the oxidizing agent in the presence of TS-1 and TS-2 as redox catalysts. A considerable increase in the epoxide selectivity was observed for different unsaturated compounds, such as allylic (allyl alcohol, allyl chloride, allyl bromide, and methylallyl chloride), open-chain, and cyclic (1-hexene and cyclohexene) and aromatic (styrene and allylbenzene) olefinic compounds, when UHP and U + HP (urea and aqueous H2O2 added separately for the in situ formation of UHP) were used as oxidants instead of aqueous H2O2. The controlled release of anhydrous H2O2 from UHP is the main reason for enhanced epoxide selectivity. Direct spectroscopic evidences for the formation of different Ti-superoxo complexes by the solid-solid interaction between TS-1/TS-2 and urea-hydrogen peroxide adduct were obtained from the characteristic continuous absorption band in the UV-vis region (300-500 nm) and the anisotropic EPR spectra for the superoxide radical attached to Ti(IV) centers on TS-1 and TS-2.
- Laha,Kumar
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p. 339 - 344
(2007/10/03)
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- Solvent effects on the kinetics of the reaction between diphenylcarbonyl oxide and olefins
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The k11 rate constants for the reaction between diphenylcarbonyl oxide and seven olefins were determined by the method of pulsed photolysis. The k11 values depend on the natures of olefins and solvents and change from 11 ± 3 for styrene in acetonitrile to (6.0 ± 0.6) × 104 dm3 mol-1 s-1 for 1,4-dichlorobutene-2 in n-decane. The rate constants for symmetrical olefins such as 1,4-dichlorobutene-2, stylbene, and cis-1,2-dichloroethylene are 1-2 orders of magnitude larger than for styrene, hexene-1, n-butyl vinyl ether, and 2-bromopropene-1. Solvent effects on k11 are considered in terms of the Winstein-Gruenwald equation. An increase in solvent polarity stabilizes carbonyl oxide and decreases the rate constant for the reaction. The products formed in the reaction between Ph2COO and styrene were studied. A possible mechanism of the reaction is discussed.
- Nazarov,Khursan,Krupin,Komissarov
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p. 1861 - 1866
(2007/10/03)
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- Production of epibromohydrin by an electromembrane process
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Epoxidations of pure or mixed dibromopropanol isomers into epibromohydrin are performed with a previously described ion-exchange membrane reactor.The theoretical relations established for the kinetic rates show the influence of the constant applied voltage.The calculated values for the epibromohydrin produced, the intermediate compound and the remaining dibromopropanol agree very well with the experimental values in the range of 0-90 V.At room temperature, the formation yield of epibromohydrin and the electric yield reach respectively 96 and 88percent for the 1,3-isomer, 69 and 52percent for the 2,3-isomer and 92 and 77percent for the mixture.The amount of intermediate compound always reaches a maximum for 30 V.By adjustment of the operating conditions, the formation yield of epibromohydrin is 98percent with an electric yield of 97percent within 90 min. - Keywords: dehydrohalogenation; dibromopropanol; epibromohydrin; membrane reactor; electro-membrane process; ion-exchange membrane; kinetic rate
- Manaf, Azzedine,Audinos, Remy
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- Epoxydation du dibromopropanol par un procede electro-membranaire
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Dibromopropanol epoxidation with an electromembrane process.The cyclodehydrohalogenation of dibromopropanols into epibromhydrin can be performed at room temperature using an electromembrane process.Epoxidation occurs in a stack fitted with ion exchange membranes when a constant direct current is applied to the end electrodes.Hydroxyl ions are continuously fed into the reacting cell as bromine ions are extracted, and so it is not necessary to use a down-stream purification of the epibromhydrin produced in such a membrane reactor.The mass yield in the reacting cell is 70 +/- 5percent, due to some diffusion of reactants and/or products through the membranes used.This method is suitable for any chemical reaction involving a pair of ions. - Keywords: dehydrohalogenation / dibromopropanol / epibromhydrin / membrane reactor / electromembrane process / ion exchange membrane
- Manaf, Azzedine,Audinos, Remy
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p. 1009 - 1014
(2007/10/02)
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- Preparation of epoxides
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This invention is a process for the preparation of an epoxide which comprises contacting a 2-haloalkyl or 2,3-dihaloalkyl carbonate, bis(2-haloalkyl- or 2,3-dihaloalkyl)carbonate, or 2-haloalkyl or 2,3-dihaloalkyl ester dissolved in a water-miscible alcohol with a sufficient amount of an aqueous solution of an alkali metal or alkaline earth metal hydroxide to provide at least one equivalent of alkali metal or alkaline earth metal hydroxide per equivalent of ester or carbonate, at a temperature of between about 0° C. and 70° C. under conditions such that an epoxide is prepared.
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- Reaction Modes of Fluorination of Cyclic Ethers by Potassium Fluoride-18-Crown-6
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The reaction scheme of the chlorine substitution of epichlorohydrin or 3,3-bis(chloromethyl)oxetane by potassium fluoride-18-crown-6-was elucidated by the aid of selectively deuterated compounds.
- Kawakami, Yuhsuke,Yamashita, Yuya
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p. 3930 - 3932
(2007/10/02)
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