- Formal synthesis of P-chiral [16O,17O,18O]phosphoenol pyruvates by means of the α-hydroxyphosphonate-phosphate rearrangement
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Transesterification of tris(hexafluoroisopropyl) phosphite with racemic 3-methyl-1-phenyl-butane-1,3-diol gave two isomeric hexafluoroisopropyl-substituted 1,2,3-dioxaphosphinanes. These cyclic phosphites were hydrolyzed rapidly and enantioselectively by water catalyzed by HCl. The respective metalated H-phosphonates were added to ethyl 3-chloropyruvate and underwent a stereospecific α-hydroxyphosphonate-phosphate rearrangement to protected phosphoenol pyruvates. This sequence with oxygen isotope-labeled enantiomers represents an alternative approach to P-chiral [16O,17O,18O]phosphoenol pyruvates.
- Malová Kri?ková, Petra,Roller, Alexander,Hammerschmidt, Friedrich
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Read Online
- Half-sandwich rhodium complexes with phenylene-based SCS ligands: Synthesis, characterization and catalytic activities for transfer hydrogenation of ketones
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A series of half-sandwich rhodium complexes with tridentate phenylene-based bis(thione) (SCS) ligand have been synthesized and characterized. Both half-sandwich rhodium complexes and phenylene-based bis(thione) compounds were fully characterized by 1H and 13C NMR spectra, mass spectrometry and single-crystal X-ray diffraction method. The catalytic activities of half-sandwich rhodium complexes toward the transfer hydrogenation of ketones to their corresponding alcohols were explored using 2-propanol as hydrogen source and solvent. And the half-sandwich rhodium complexes exhibited high catalytic activity for transfer hydrogenation of ketones with a broad functional group tolerance.
- Jia, Wei-Guo,Gao, Li-Li,Zhi, Xue-Ting,Li, Xiao-Dong,Wang, Zhi-Bao,Sun, Ying
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- Postsynthetic Modification of Half-Sandwich Ruthenium Complexes by Mechanochemical Synthesis
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A mild and environmentally friendly method to synthesize half-sandwich ruthenium complexes through the Wittig reaction between an aldehyde-tagged half-sandwich ruthenium complex and phosphorus ylide mechanochemically is reported herein. The mechanochemical synthesis of valuable half-sandwich ruthenium complexes resulted in a fast reaction, good yield with simple workup, and the avoidance of harsh reaction conditions and organic solvents. The synthesized half-sandwich ruthenium complexes exhibited high catalytic activity for transfer hydrogenation of ketones using 2-propanol as the hydrogen source and solvent. Density functional theory was carried out to propose a mechanism for the transfer hydrogenation process. The modeling suggests the importance of the labile p-cymene ligand in modulating the reactivity of the catalyst.
- Jia, Wei-Guo,Zhi, Xue-Ting,Li, Xiao-Dong,Zhou, Jun-Peng,Zhong, Rui,Yu, Haibo,Lee, Richmond
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p. 4313 - 4321
(2021/05/04)
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- Preparation of Organic Nitrates from Aryldiazoacetates and Fe(NO3)3·9H2O
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A thermal protocol is reported for the formal insertion of nitric acid into aryldiazoacetates using Fe(NO3)3·9H2O. This strategy is mild and high yielding and allows the preparation of a large variety of members of an unprecedented family of organic nitrates. The nitrate group can be also readily transformed into other functional groups and heterocyclic moieties and can possibly allow new biological explorations of untapped potential associated with their NO-releasing ability.
- Thurow, Samuel,Fernandes, Alessandra A. G.,Quevedo-Acosta, Yovanny,De Oliveira, Matheus F.,De Oliveira, Marcelo G.,Jurberg, Igor D.
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supporting information
p. 6909 - 6913
(2019/09/12)
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- A Well-Defined Osmium-Cupin Complex: Hyperstable Artificial Osmium Peroxygenase
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Thermally stable TM1459 cupin superfamily protein from Thermotoga maritima was repurposed as an osmium (Os) peroxygenase by metal-substitution strategy employing the metal-binding promiscuity. This novel artificial metalloenzyme bears a datively bound Os ion supported by the 4-histidine motif. The well-defined Os center is responsible for not only the catalytic activity but also the thermodynamic stability of the protein folding, leading to the robust biocatalyst (Tm ≈ 120 °C). The spectroscopic analysis and atomic resolution X-ray crystal structures of Os-bound TM1459 revealed two types of donor sets to Os center with octahedral coordination geometry. One includes trans-dioxide, OH, and mer-three histidine imidazoles (O3N3 donor set), whereas another one has four histidine imidazoles plus OH and water molecule in a cis position (O2N4 donor set). The Os-bound TM1459 having the latter donor set (O2N4 donor set) was evaluated as a peroxygenase, which was able to catalyze cis-dihydroxylation of several alkenes efficiently. With the low catalyst loading (0.01% mol), up to 9100 turnover number was achieved for the dihydroxylation of 2-methoxy-6-vinyl-naphthalene (50 mM) using an equivalent of H2O2 as oxidant at 70 °C for 12 h. When octene isomers were dihydroxylated in a preparative scale for 5 h (2% mol cat.), the terminal alkene octene isomers was converted to the corresponding diols in a higher yield as compared with the internal alkenes. The result indicates that the protein scaffold can control the regioselectivity by the steric hindrance. This protein scaffold enhances the efficiency of the reaction by suppressing disproportionation of H2O2 on Os reaction center. Moreover, upon a simple site-directed mutagenesis, the catalytic activity was enhanced by about 3-fold, indicating that Os-TM1459 is evolvable nascent osmium peroxygenase.
- Fujieda, Nobutaka,Nakano, Takumi,Taniguchi, Yuki,Ichihashi, Haruna,Sugimoto, Hideki,Morimoto, Yuma,Nishikawa, Yosuke,Kurisu, Genji,Itoh, Shinobu
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supporting information
p. 5149 - 5155
(2017/05/04)
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- Amine Catalysis for the Organocatalytic Diboration of Challenging Alkenes
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The generation of in situ sp2–sp3diboron adducts has revolutionised the synthesis of organoboranes. Organocatalytic diboration reactions have represented a milestone in terms of unpredictable reactivity of these adducts. However, current methodologies have limitations in terms of substrate scope, selectivity and functional group tolerance. Here a new methodology based on the use of simple amines as catalyst is reported. This methodology provides a completely selective transformation overcoming current substrate scope and functional/protecting group limitations. Mechanistic studies have been included in this report.
- Farre, Albert,Soares, Kaline,Briggs, Rachel A.,Balanta, Angelica,Benoit, David M.,Bonet, Amadeu
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p. 17552 - 17556
(2016/11/28)
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- ERK INHIBITORS
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The present invention provides a compound of Formula (I) or the pharmaceutically acceptable salts, esters, and prodrugs thereof, which are ERK2 inhibitors. The invention also provides a method of inhibiting ERK2 in a patient in need of such treatment comprising administering to said patient an effective amount of at least one compound of Formula (I). The invention also provides a method for treating cancer in a patient in need of such treatment, said method comprising administering to said patient an effective amount of at least one compound of Formula (I).
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Page/Page column 66-67
(2016/07/05)
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- Synthesis of oxacyclic scaffolds via dual ruthenium hydride/Bronsted acid-catalyzed isomerization/cyclization of allylic ethers
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A ruthenium hydride/Bronsted acid-catalyzed tandem sequence is reported for the synthesis of 1,3,4,9-tetrahydropyrano[3,4-b]indoles (THPIs) and related oxacyclic scaffolds. The process was designed on the premise that readily available allylic ethers would undergo sequential isomerization, first to enol ethers (Ru catalysis), then to oxocarbenium ions (Bronsted acid catalysis) amenable to endo cyclization with tethered nucleophiles. This methodology provides not only an attractive alternative to the traditional oxa-Pictet-Spengler reaction for the synthesis of THPIs, but also convenient access to THPI congeners and other important oxacycles such as acetals.
- Ascic, Erhad,Ohm, Ragnhild G.,Petersen, Rico,Hansen, Mette R.,Hansen, Casper L.,Madsen, Daniel,Tanner, David,Nielsen, Thomas E.
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supporting information
p. 3297 - 3300
(2014/04/03)
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- Magnetically recoverable osmium catalysts with osmium-diolate esters for dihydroxylation of olefins
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We prepared magnetically recoverable osmium catalysts with stable osmium-diolate esters and applied them to the dihydroxylation of olefins. By employing 2 mol% of the magnetic osmium catalyst, the dihydroxylation reaction proceeded smoothly to provide the corresponding vicinal diol with a low level of osmium leaching. After completion of the dihydroxylation, the osmium catalyst was readily recovered by use of an external magnet and was recycled up to five times. Georg Thieme Verlag Stuttgart . New York.
- Fujita, Ken-Ichi,Umeki, Satoshi,Yasuda, Hiroyuki
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p. 947 - 950
(2013/07/19)
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- Homogeneous dihydroxylation of olefins catalyzed by OsO4 2- immobilized on a dendritic backbone with a tertiary nitrogen at its core position
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OsO42- immobilized on a poly(benzyl ether) dendrimer with a tertiary nitrogen at its core position efficiently catalyzed the homogeneous dihydroxylation of olefins with a low level of osmium leaching. The dendritic osmium catalyst could be applied to the wide range of olefins. Furthermore, the dendritic osmium catalyst was recovered by reprecipitation and then reused up to five times.
- Fujita, Ken-Ichi,Inoue, Kensuke,Tsuchimoto, Teruhisa,Yasuda, Hiroyuki
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p. 1594 - 1598
(2013/02/23)
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- Magnetically recoverable osmium catalysts for dihydroxylation of olefins
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We prepared magnetically recoverable osmium catalysts by use of magnetite, quaternary ammonium salts, and potassium osmate(VI), and applied them to the dihydroxylation of olefins. By employing 2 mol% of the magnetic osmium catalyst, the dihydroxylation reaction proceeded smoothly to provide the corresponding vicinal diol in a good chemical yield. The osmium catalyst was readily recovered by use of an external magnet, and was reused repeatedly.
- Fujita, Ken-Ichi,Umeki, Satoshi,Yamazaki, Manabu,Ainoya, Taku,Tsuchimoto, Teruhisa,Yasuda, Hiroyuki
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experimental part
p. 3137 - 3140
(2011/06/28)
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- A recyclable dendritic osmium catalyst for homogeneous dihydroxylation of olefins
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A series of osmate (OsO42-) core dendrimers was prepared by an ion-exchange technique through the mixing of K 2OsO4 and a bis(quaternary ammonium bromide) core dendrimer, which consisted of poly(benzyl ether) dendron. By employing an osmate core dendrimer as a homogeneous catalyst, dihydroxylation reactions of olefins proceeded rapidly, and the dendritic osmium catalyst was recovered by reprecipitation and then reused. Furthermore, a dendritic effect on the recyclability of a catalyst was observed. In the case of asymmetric dihydroxylation reactions, the corresponding diol was obtained in a high chemical yield with a fair enantiomeric excess (ee). In this case, not only the dendritic osmium catalyst but also the chiral ligand could be recovered by reprecipitation and reused efficiently up to five times.
- Fujita, Ken-Ichi,Yamazaki, Manabu,Ainoya, Taku,Tsuchimoto, Teruhisa,Yasuda, Hiroyuki
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experimental part
p. 8536 - 8543
(2010/11/18)
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- Homogeneous dihydroxylation of olefins catalyzed by a recyclable OsO42 - core dendrimer
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By employing an osmate (OsO42 -) core dendrimer as a catalyst, homogeneous dihydroxylation reactions proceeded rapidly, and the dendritic osmium catalyst was efficiently recycled by reprecipitation.
- Fujita, Ken-ichi,Ainoya, Taku,Tsuchimoto, Teruhisa,Yasuda, Hiroyuki
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experimental part
p. 808 - 810
(2010/03/26)
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- Osmium-catalyzed asymmetric dihydroxylation by carbon dioxide-activated hydrogen peroxide and N-methylmorpholine
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An improved process has been developed for the osmium-catalyzed dihydroxylation of olefins via in situ formation of NMO from NMM using CO2 catalysis and H2O2. All olefins examined were selectively cis-dihydroxylated to their corresponding diols in good to excellent yields, and by the use of chiral ligands, high enantiomeric excesses were obtained.
- Balagam, Bharathi,Mitra, Ranjan,Richardson, David E.
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p. 1071 - 1075
(2008/09/18)
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- Preparation, characterization and catalytic properties of polyaniline-supported metal complexes
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Polyaniline-supported Sc, In, Pd, Os and Re catalysts were prepared by using a simple protocol and the thus prepared catalysts were well characterized using FTIR, XPS, UV-Vis/DRS, TGA-DTA. All the catalysts were successfully employed in a wide range of organic transformations such as cyanation and allylation of carbonyl compound, Suzuki coupling of aryl halides and boronic acids, and, most importantly, in asymmetric dihydroxylation of olefins to afford optically active vicinal diols. All the catalysts were separated from the reaction mixture by simple filtration and reused with consistent activity for five cycles without noticeable leaching of metal from the support.
- Choudary, Boyapati M.,Roy, Moumita,Roy, Sarabindu,Kantam, M. Lakshmi,Sreedhar, Bojja,Kumar, Karasala Vijay
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p. 1734 - 1742
(2007/10/03)
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- PREPARATION OF ALPHA-HYDROXYKETONES
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A process for the preparation of an 1, 1 -disubstituted oxirane is disclosed, wherein an organic sulphide is reacted in a polar solvent with an educt containing a leaving group attached to a primary or secondary carbon atom, and/or the sulfonium salt formed in this way is reacted with a ketone in presence of a base and a polar solvent. Oxiranes of the type obtained may be further converted into the corresponding α-hydroxyketone or α-aminoketone, either in one step by subjecting to aerobic oxidation in the presence of a transition metal catalyst, or in two steps by hydrolyzation in the presence of an aqueous acid to the corresponding dialcohol and subsequent selective oxidation. Further described are some novel epoxide intermediates. The α-hydroxyketones and α-aminoketones thus obtainable are useful inter alga as photoinitiators.
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- Microencapsulation of osmium tetroxide in polyurea
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(Matrix presented) Osmium tetroxide has been microencapsulated in a polyurea matrix using an in situ interfacial polymerization approach. These microcapsules have been effectively used as recoverable and reusable catalysts in the dihydroxylation of olefins.
- Ley, Steven V.,Ramarao, Chandrashekar,Lee, Ai-Lan,stergaard, Niels,Smith, Stephen C.,Shirley, Ian M.
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p. 185 - 187
(2007/10/03)
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- Osmium-catalyzed asymmetric dihydroxylation of olefins by H2O2 using a biomimetic flavin-based coupled catalytic system
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Selective cis-dihydroxylation of olefins with the aid of a triple catalytic system using H2O2 as the terminal oxidant has been developed. In this process Os(VI) is recycled to Os(VIII) by a coupled electron-transfer-mediator system based on N-methylmorpholine and a biomimetic flavin, leading to a mild and selective electron transfer. Aliphatic, aromatic, and functionalized olefins were successfully cis-dihydroxylated, employing the triple catalytic system. The present biomimetic catalytic system works well in asymmetric dihydroxylation and gave optically active diols in good isolated yields and high enantiomeric excesses (up to 99% ee).
- Jonsson,Faernegardh,Baeckvall
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p. 1365 - 1371
(2007/10/03)
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- Synthesis of unsymmetrical diolate, oxametallacyclopentene, amido-alkoxide and thiolato-alkoxide complexes using dialkyl and diaryl titanium aminotroponiminate complexes: A route to unsymmetrical vicinal diols
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The reactivity of [TiR2(Me2ATI)2] complexes, where Me2ATI = N,N′-dimethylaminotroponiminate, or L, with CO or RNC in the presence of various organic electrophiles has been investigated. The compounds TiMe2L2 and TiPh2L2 react with CO and aldehydes or ketones to afford unsymmetrical diolate complexes that convert to the corresponding vicinal diols after hydrolysis. Phenyl acetylene also reacts to form the oxametallacyclopentene complex [Ti(OCMe2CH=CPh)(Me2ATI)2]. Treatment of TiMe2L2 with RNC yields the free imine and a source of low-valent titanium. Trapping this intermediate with 2 equiv of benzaldehyde or benzil affords the titanium diolate or enediolate complex, respectively. When 1 equiv each of benzophenone and either N-tosylbenzaldimine or acetone were added to the intermediate, [Ti(Ph2COCN(SO2tol)HPh)(Me2-ATI)2] and [Ti(Ph2COCOMe2)(Me2ATI)2], respectively, were obtained. The titanium thiolato-alkoxide complex [Ti(Ph2CSCOMe2)(Me2ATI)2] was prepared by use of thiobenzophenone and acetone. This chemistry allows for the preparation of unsymmetrical diols and oxametallacyclopentene complexes from Ti(IV) dialkyls, CO, and either carbonyl compounds or alkynes. Amido-alkoxide and thiolato-alkoxide complexes can be prepared by the reaction of Ti(IV) dialkyl complex, 2 equiv of benzophenone, and either an imine or thioketone.
- Steinhuebel, Dietrich P.,Lippard, Stephen J.
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p. 11762 - 11772
(2007/10/03)
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- Novel self-coupling reaction of cyclic ketones under a high-pressure mercury lamp
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A novel self-coupling reaction in alcohol or hexane-water of cycloalkanone (cycloheptanone, cyclooctanone, and cyclododecanone) with irradiation under a high-pressure mercury lamp yielded the corresponding pinacol-type compound in good yields. In the case of cyclohexanone, 2-methyl-, 2-phenyl-, 4-methylcyclohexanone, 5α- and 5β-cholestan-3-one, the pinacol derivatives were not obtained and the dimethyl acetals were given.
- Ji, Shun-Jun,Matsushita, Masatoshi,Takahashi, T. Tomoyoshi,Horiuchi, C. Akira
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p. 6791 - 6794
(2007/10/03)
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- Reductive coupling of aldehydes, ketones and aroyl chlorides induced by lvt prepared from TiCl4/Al system
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Aluminium powder has been used to reduce titanium tetrachloride to generate the low valent titanium (LVT)reagent which can induce the reductive coupling of aldehydes and ketones to form the corresponding pinacols or olefins. However, arylsulfonyl chlorides will give diaryldisulfides under the same condition.
- Hu, Yulai,Du, Zhengyin,Wang, Jin-Xian,Xi, Yongsheng,Gu, Shengjiu
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p. 3299 - 3304
(2007/10/03)
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- Reactivity and Selectivity in the Oxidation of Styrene Derivatives. IV. Studies on the Oxidation of Substituted β,β-Dimethylstyrenes
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The liquid phase oxidation of substituted (p-MeO-, p-Cl-, m-CF3-) 2-aryl-3-methyl-but-2-enes, of 1,1-diphenyl-2-methyl-propene, of 1-ethoxy-2-methyl-1-phenyl-propene and of 9-isopropylidene-fluorene with pure oxygen was investigated in chlorobenzene solution and in presence of cumene and of cumene hydroperoxide in the temperature range 65-125°C. The product yields were determined gaschromatographically. The differences of the activation energies of epoxide formation and the parallel reactions were calculated. They amount to 19-48 kJ/mol. The epoxide selectivity increases with increasing temperature and increasing concentration of olefin. The relative chain propagation constants (kpC=C) were determined by competitive oxidation with cumene. The kpC=C values of substituted β,β-dimethylstyrenes can be correlated by a LFE-relationship with the ionisation energies of the olefins.
- Suprun
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p. 247 - 255
(2007/10/03)
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- Microbiological transformations 32: Use of epoxide hydrolase mediated biohydrolysis as a way to enantiopure epoxides and vicinal diols: Application to substituted styrene oxide derivatives
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The biohydrolyses of various substituted styrene oxide derivatives using the fungi Aspergillus niger or Beauveria sulferescens are described. The results obtained show that this methodology allows the preparation of enantiomerically enriched epoxides and diols via enantioselective and regioselective hydration. The comparative study of the results obtained suggests that these hydrolyses operate following different mechanisms and a model of the corresponding active sites is proposed.
- Pedragosa-Moreau,Archelas,Furstoss
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p. 4593 - 4606
(2007/10/03)
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