- Synthesis of new chiral Mn(iii)-salen complexes as recoverable and reusable homogeneous catalysts for the asymmetric epoxidation of styrenes and chromenes
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New chiral Mn(iii)-salen complexes 1a-e and 2a-e were synthesized from the reaction of C2-symmetric chiral salen ligands and Mn(CH3COO)2·4H2O under an inert atmosphere followed by aerobic oxidation. These complexes were obtained in 91-96% yields and characterized by HRMS, FT-IR, UV-visible spectroscopy, TGA, and elemental analysis. The chiral Mn(iii)-salen complexes 1a-e and 2a-e were evaluated in the asymmetric epoxidation of styrene using NaOCl as an oxidant in ethyl acetate as a green solvent. The chiral Mn(iii)-salen complexes 1b and 2b (2 mol%) catalyzed the asymmetric epoxidation of substituted styrenes and chromenes to afford the corresponding epoxides in 95-98% yields with 29-88% ee's. The catalysts 1b and 2b were recovered and reused for up to 2 and 3 runs, respectively, in the asymmetric epoxidation of styrene, and the yield of styrene oxide gradually decreased but the ee was consistent.
- Chaudhary, Pooja,Damodaran, Krishna K.,Singh, Surendra,Yadav, Geeta Devi
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p. 1308 - 1318
(2022/02/07)
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- The Stereoselective Oxidation of para-Substituted Benzenes by a Cytochrome P450 Biocatalyst
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The serine 244 to aspartate (S244D) variant of the cytochrome P450 enzyme CYP199A4 was used to expand its substrate range beyond benzoic acids. Substrates, in which the carboxylate group of the benzoic acid moiety is replaced were oxidised with high activity by the S244D mutant (product formation rates >60 nmol.(nmol-CYP)?1.min?1) and with total turnover numbers of up to 20,000. Ethyl α-hydroxylation was more rapid than methyl oxidation, styrene epoxidation and S-oxidation. The S244D mutant catalysed the ethyl hydroxylation, epoxidation and sulfoxidation reactions with an excess of one stereoisomer (in some instances up to >98 %). The crystal structure of 4-methoxybenzoic acid-bound CYP199A4 S244D showed that the active site architecture and the substrate orientation were similar to that of the WT enzyme. Overall, this work demonstrates that CYP199A4 can catalyse the stereoselective hydroxylation, epoxidation or sulfoxidation of substituted benzene substrates under mild conditions resulting in more sustainable transformations using this heme monooxygenase enzyme.
- Chao, Rebecca R.,Lau, Ian C.-K.,Coleman, Tom,Churchman, Luke R.,Child, Stella A.,Lee, Joel H. Z.,Bruning, John B.,De Voss, James J.,Bell, Stephen G.
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p. 14765 - 14777
(2021/09/14)
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- Peroxygenase-Catalysed Epoxidation of Styrene Derivatives in Neat Reaction Media
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Biocatalytic oxyfunctionalisation reactions are traditionally conducted in aqueous media limiting their production yield. Here we report the application of a peroxygenase in neat reaction conditions reaching product concentrations of up to 360 mM.
- Alcalde, Miguel,Arends, Isabel W. C. E.,Hollmann, Frank,Paul, Caroline E.,Rauch, Marine C. R.,Tieves, Florian
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- Asymmetric synthesis of α-bromohydrins by carrot root as biocatalyst and conversion to enantiopure β-hydroxytriazoles and styrene oxides using click chemistry and SN2 ring-closure
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In this study we have combined the bioreduction of α-bromoketones using carrot root as biocatalyst and click chemistry for the preparation of enantiopure β-hydroxytriazoles in excellent enantiomeric excesses and yields. Moreover, we have utilized chiral α-halohydrins for the synthesis of enantiopure styrene oxides in very good yields and enantiomeric excesses. Structural assignments of the products were based on their 1H and 13C NMR data and their optical rotations. The enantiomeric excess of the chiral products was obtained by HPLC analysis.
- Hosseinzadeh, Rahman,Mohadjerani, Maryam,Mesgar, Sakineh
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p. 583 - 591
(2019/02/17)
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- Highly Enantioselective Hydrosilylation of Ketones Catalyzed by a Chiral Oxazaborolidinium Ion
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A highly enantioselective hydrosilylation of ketones was developed for the synthesis of a variety of chiral secondary alcohols. In the presence of a chiral oxazaborolidinium ion (COBI) catalyst, the reaction proceeded with good yields (up to 99%) with excellent enantioselectivities (up to 99% ee).
- Kang, Byung Chul,Shin, Sung Ho,Yun, Jaesook,Ryu, Do Hyun
-
supporting information
p. 6316 - 6319
(2017/12/08)
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- Multistep Organic Transformations over Base-Rhodium/Diamine-Bifunctionalized Mesostructured Silica Nanoparticles
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The assembly of multiple catalytic functionalities within a single mesoporous silica as a catalyst for multistep enantioselective organic transformations in an environmentally friendly medium is a significant challenge in heterogeneous asymmetric catalysis. Herein, we took advantage of a BF4 ? anion hydrogen bonding strategy to anchor a chiral cationic rhodium/diamine complex within base-functionalized mesostructured silica nanoparticles conveniently to construct a bifunctional heterogeneous catalyst. The solid-state 13C NMR spectrum discloses the well-defined chiral Rh/diamine active species, and we used XRD, N2 adsorption–desorption, and electron microscopy to reveal the ordered mesostructure. The combination of bifunctionality in the silica nanoparticles enables two kinds of efficient enantioselective organic transformations with high yields and enantioselectivities, in which the asymmetric transfer hydrogenation of α-haloketones followed by epoxidation provides various chiral aryloxiranes, and the amination of α-haloketones with anilines followed by asymmetric transfer hydrogenation produces various β-amino alcohols. Furthermore, the catalyst can be recovered and recycled for seven times without a loss of catalytic activity, which is an attractive feature for multistep organic transformations in a sustainable benign process.
- Liao, Hang,Chou, Yajie,Wang, Yu,Zhang, Han,Cheng, Tanyu,Liu, Guohua
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p. 3197 - 3202
(2017/08/29)
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- The Activation of Carboxylic Acids via Self-Assembly Asymmetric Organocatalysis: A Combined Experimental and Computational Investigation
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The heterodimerizing self-assembly between a phosphoric acid catalyst and a carboxylic acid has recently been established as a new activation mode in Br?nsted acid catalysis. In this article, we present a comprehensive mechanistic investigation on this activation principle, which eventually led to its elucidation. Detailed studies are reported, including computational investigations on the supramolecular heterodimer, kinetic studies on the catalytic cycle, and a thorough analysis of transition states by DFT calculations for the rationalization of the catalyst structure-selectivity relationship. On the basis of these investigations, we developed a kinetic resolution of racemic epoxides, which proceeds with high selectivity (up to s = 93), giving the unreacted epoxides and the corresponding protected 1,2-diols in high enantiopurity. Moreover, this approach could be advanced to an unprecedented stereodivergent resolution of racemic α-chiral carboxylic acids, thus providing access to a variety of enantiopure nonsteroidal anti-inflammatory drugs and to α-amino acid derivatives.
- Monaco, Mattia Riccardo,Fazzi, Daniele,Tsuji, Nobuya,Leutzsch, Markus,Liao, Saihu,Thiel, Walter,List, Benjamin
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supporting information
p. 14740 - 14749
(2016/11/18)
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- Azidolysis of epoxides catalysed by the halohydrin dehalogenase from Arthrobacter sp. AD2 and a mutant with enhanced enantioselectivity: an (S)-selective HHDH
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Halohydrin dehalogenase from Arthrobacter sp. AD2 catalysed azidolysis of epoxides with high regioselectivity and low to moderate (S)-enantioselectivity (E?=?1–16). Mutation of the asparagine 178 to alanine (N178A) showed increased enantioselectivity towards styrene oxide derivatives and glycidyl ethers. Conversion of aromatic epoxides was catalysed by HheA-N178A with complete enantioselectivity, however the regioselectivity was reduced. As a result of the enzyme-catalysed reaction, enantiomerically pure (S)-β-azido alcohols and (R)-α-azido alcohols (ee???99%) were obtained.
- Mikleu?evi?, Ana,Primo?i?, Ines,Hrenar, Tomica,Salopek-Sondi, Branka,Tang, Lixia,Elenkov, Maja Majeri?
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p. 930 - 935
(2016/09/13)
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- Catalytic Enantioselective Conversion of Epoxides to Thiiranes
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A highly efficient and enantioselective Br?nsted acid catalyzed conversion of epoxides to thiiranes has been developed. The reaction proceeds in a kinetic resolution, furnishing both epoxide and thiirane in high yields and enantiomeric purity. Heterodimer formation between the catalyst and sulfur donor affords an effective way to prevent catalyst decomposition and enables catalyst loadings as low as 0.01 mol %.
- Liao, Saihu,Leutzsch, Markus,Monaco, Mattia Riccardo,List, Benjamin
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supporting information
p. 5230 - 5233
(2016/05/19)
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- Self-supported chiral polymeric MnIII salen complexes as highly active and recyclable catalysts for epoxidation of nonfunctionalized olefins
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Abstract A series of self-supported chiral polymeric MnIII N,N′-ethylenebis(salicylimine) (salen) complexes were synthesized through metalation of the corresponding salen ligands obtained by condensation of several bis/tris-aldehydes with (1R,2
- Roy, Tamal,Kureshy, Rukhsana I.,Khan, Noor-Ul H.,Abdi, Sayed H. R.,Bajaj, Hari C.
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p. 1038 - 1044
(2015/06/08)
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- Nonenzymatic Regeneration of Styrene Monooxygenase for Catalysis
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Styrene monooxygenase (SMO) is a two-component flavoprotein catalyzing the selective epoxidation of various C=C double bonds. For cell-free catalysis, traditionally a cascade of NAD(P)H:flavin oxidoreductase, nicotinamide cofactor (NADH), and NADH regener
- Paul, Caroline E.,Tischler, Dirk,Riedel, Anika,Heine, Thomas,Itoh, Nobuya,Hollmann, Frank
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p. 2961 - 2965
(2015/09/08)
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- Asymmetric synthesis of 2-arylpiperazines
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An asymmetric synthesis of 2-arylpiperazines starting from phenacyl bromides, a variety of which are easily available, has been established. The synthesis features a CBS reduction of phenacyl bromide to provide optically enriched compounds, an SN2 reaction of 1,2,3-oxathiazolidine 2-oxides with an azide anion with invert of configuration, and construction of the piperazine ring via reduction of piperazine-2,3-diones.
- Yokoshima, Satoshi,Watanabe, Kazutoshi,Uehara, Fumiaki,Usui, Yoshihiro,Tanaka, Hiroshi
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p. 5749 - 5751
(2015/02/19)
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- Enhanced turnover rate and enantioselectivity in the asymmetric epoxidation of styrene by new T213G mutants of CYP 119
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New CYP 119 T213G mutants were constructed and characterized. Introduction of the T213G mutation into the wild-type CYP 119 significantly enhances the turnover rate for the peroxide-dependent styrene epoxidation 4.4-fold to 346.2 min-1, and the
- Zhang, Chun,Li, Jing,Yang, Bo,He, Fang,Yang, Sheng-Yong,Yu, Xiao-Qi,Wang, Qin
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p. 27526 - 27531
(2014/07/21)
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- A mononuclear manganese complex of a tetradentate nitrogen ligand - Synthesis, characterizations, and application in the asymmetric epoxidation of olefins
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A new chiral manganese complex (C1) bearing a tetradentate nitrogen ligand containing chiral bipyrrolidine and benzimidazole moieties was prepared. The structure of C1 was confirmed by ESI-MS and crystallography. This manganese complex is an active catalyst for the asymmetric epoxidation of various olefins with excellent conversion (up to 99%) and high enantiomeric excess (up to 96%ee) with hydrogen peroxide as the oxidant in the presence of 2-ethylhexanoic acid or acetic acid. Compared with previous structurally similar manganese complexes with different diamine backbones (C2, cyclohexanediamine; C3, diamine from L-proline), C1 showed improved asymmetric induction, especially for simple olefins such as styrene derivatives and substituted chromene. The possible reasons for the improvement of the ee values are discussed in the text on the basis of the crystal structures of the manganese complexes.
- Shen, Duyi,Miao, Chengxia,Wang, Shoufeng,Xia, Chungu,Sun, Wei
-
supporting information
p. 5777 - 5782
(2015/02/19)
-
- Engineered P450pyr monooxygenase for asymmetric epoxidation of alkenes with unique and high enantioselectivity
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A triple mutant of P450pyr monooxygenase (P450pyrTM) catalysed the epoxidation of several para-substituted styrenes as the first enzyme showing high (R)-enantioselectivity and high conversion, demonstrated a broad substrate range, and showed high enantioselectivity for the epoxidation of an unconjugated 1,1-disubstituted alkene, 2-methyl-3-phenyl-1-propene, and a cyclic alkene, N-phenoxycarbonyl-1,2,5,6-tetrahydropyridine, respectively.
- Li, Aitao,Liu, Ji,Pham, Son Q.,Li, Zhi
-
supporting information
p. 11572 - 11574
(2013/12/04)
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- Crystalline Form Of A Cyclopropyl Benzamide Derivative
-
The present invention relates to a crystalline form of compound (I), 4-{(1S,2S)-2-[(4-cyclobutylpiperazin-1-yl)carbonyl]-cyclopropyl}-benzamide, pharmaceutical formulations containing said compound and to the use of said active compound in therapy.
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-
-
- Solid Forms Comprising A Cyclopropyl Amide Derivative
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This disclosure relates to at least one solid form of 4-{(1S, 2S)-2-[((R)-4-cyclobutyl-2-methylpiperazin-1-yl)carbonyl]-cyclopropyl}-benzamide. This disclosure also relates to at least one pharmaceutical composition comprising at least one solid form described herein, methods of using the solid forms and pharmaceutical compositions comprised thereof, and processes of manufacturing the solid forms.
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- On the configurational stability of α-lithiated sulfurated styrene oxides: Synthetic and mechanistic aspects
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The configurational stability of some sulfurated styrene oxides has been investigated. Chemical studies have shown that in THF at 157 K α-lithiated ortho-and paraphenylthiostyrene oxides are configurationally unstable and undergo a fast racemization on the time scale of the reaction, whereas α-lithiated meta-phenylthiostyrene oxide retains its stereochemical integrity for at least 60 min. The deprotonation-trapping methodology has also been employed for the preparation of a sulfurated β-aminoalcohol effective for the fight against phytopathogenic fungi. Copyright Taylor and Francis Group, LLC.
- Capriati, Vito,Dammacco, Mariangela,Florio, Saverio,Perna, Filippo M.,Salomone, Antonio
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scheme or table
p. 1274 - 1277
(2011/09/15)
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- Cyclopropyl Amide Derivatives
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Disclosed herein is at least one cyclopropyl amide derivative, at least one pharmaceutical composition comprising at least one cyclopropyl amide derivative disclosed herein, and at least one method of using at least one cyclopropyl amide derivative disclosed herein for treating at least one histamine H3 receptor associated condition therewith.
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Page/Page column 53
(2010/09/05)
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- Synthesis of highly modular bis(oxazoline) ligands by Suzuki cross-coupling and evaluation as catalytic ligands
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New bis(oxazoline) ligands (BOXs) containing biaryl substitutents at the C-4 position and H or CH2OR substituents at the C-5 position have been synthesized using Suzuki cross-coupling as the main tool for structural diversity. Copper, zinc, and
- Catto?n, Xavier,Pericàs, Miquel A.
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experimental part
p. 8199 - 8205
(2009/12/24)
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- Asymmetric epoxidation of styrenes catalyzed by molybdenum complexes with amino alcohol ligands
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Two common amino alcohols, prolinol and isolucinol, and their derivatives have been screened to coordinate with MoO2(acac)2 to form in situ catalysts for asymmetric epoxidation of styrenes with the highest enantioselectivity of 84% for 4-fluoro-styrene under the optimized reaction conditions.
- Wang, Yi,Wu, Zhiqing,Li, Zhengkai,Zhou, Xiang-Ge
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experimental part
p. 2509 - 2511
(2009/09/05)
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- Asymmetric epoxidation of olefins with chiral bioinspired manganese complexes
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Image Presented A novel series of chiral tetradentate N4 ligands together with their manganese complexes have been designed and synthesized. With 1 mol % manganese catalyst loading, the enantioselective epoxidation of olefins proceeds with nearly full conversion and enantiomeric excess values of up to 89 % for the first time.
- Wu, Mei,Wang, Bin,Wang, Shoufeng,Xia, Chungu,Sun, Wei
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supporting information; experimental part
p. 3622 - 3625
(2011/02/22)
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- MORPHOLINYL AND PYRROLIDINYL ANALOGS
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The present invention relates to morpholinyl, and pyrrolidinyl analogs, pharmaceutical compositions containing them, and their use as antagonists of urotensin II.
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Page/Page column 144
(2008/06/13)
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- PIPERAZINE DERIVATIVES AND THEIR USE IN THERAPY
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Compounds of formula (I) and their use in therapy, particularly for the treatment of a disorder mediated by CB1 receptors wherein R1 is a radical of formula -(Alk1)m-(NH)p-(Alk2)n/sub
- -
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Page/Page column 26-27
(2008/06/13)
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- A novel method for the synthesis of chiral epoxides from styrene derivatives using chiral acids in presence of Pseudomonas lipase G6 [PSL G6] and hydrogen peroxide
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Chiral epoxidation of styrene and its derivatives was carried out using series of chiral acids and urea hydrogen peroxide (UHP) or aqueous hydrogen peroxide (50%) in two phases under the catalytic influence of immobilized Pseudomonas lipase G6 [PSL G6] at 25-55 °C. A moderate to good yield and enantioselectivities of chiral epoxides were obtained.
- Sarma, Kuladip,Bhati, Nishi,Borthakur, Naleen,Goswami, Amrit
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p. 8735 - 8741
(2008/02/09)
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- COMPOUNDS WHICH POTENTIATE GLUTAMATE RECEPTOR AND USES THEREOF IN MEDICINE
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This invention relates to potentiation of the glutamate receptor by novel compounds of formula (I): The invention also relates to the use of the derivatives in treating diseases and conditions mediated by potentiation of the glutamate receptor, compositio
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Page/Page column 44
(2008/06/13)
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- Chiral styrene oxides from α-haloacetophenones using NaBH4 and TarB-NO2, a chiral Lewis acid
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High enantioselectivities are obtained for the preparation of chiral styrene oxides through reduction of α-haloacetophenones using TarB-NO 2 reagent and the inexpensive and mild reducing agent NaBH 4. The epoxides are easily obtained in up to 95% ee through routine acid-base workup of the product alcohols. Either the (R) or (S) epoxide can be obtained by using the appropriate l- or d-tartaric acid starting material in the TarB-NO2 reagent.
- Cordes, David B.,Kwong, Tracey J.,Morgan, Kellie A.,Singaram, Bakthan
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p. 349 - 351
(2007/10/03)
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- Effective asymmetric epoxidation of styrenes by chiral dioxirane
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High enantioselectivity (80-92% enantiomeric excess (ee)) has been obtained for the epoxidation of various styrenes using an easily prepared ketone (4) catalyst.
- Goeddel, David,Shu, Lianhe,Yuan, Yi,Wong, O. Andrea,Wang, Bin,Shi, Yian
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p. 1715 - 1717
(2007/10/03)
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- Stereospecific biocatalytic epoxidation: The first example of direct regeneration of a FAD-dependent monooxygenase for catalysis
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Catalysis for chemical synthesis by cell-free monooxygenases necessitates an efficient and robust in situ regeneration system to supply the enzyme with reducing equivalents. We report on a novel approach to directly regenerate flavin-dependent monooxygena
- Hollmann, Frank,Lin, Po-Chi,Witholt, Bernard,Schmid, Andreas
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p. 8209 - 8217
(2007/10/03)
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- Stereo- and enantioselective alkene epoxidations: A comparative study of D4- and D2-symmetric homochiral trans-dioxoruthenium(VI) porphyrins
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The mechanism of stoichiometric enantioselective alkene epoxidations by the D4- and D2-symmetric homochiral trans-dioxoruthenium(VI) porphyrins, [RuVI(D4-Por*)O2] (1) and [RuVI(D2-Por*)O2] (2a), in the presence of pyrazole (Hpz) was studied by UV/ Vis spectrophotometry and analysis of the organic products. The enantioselectivity of styrene oxidations is more susceptible to steric effects than to substituent electronic effects. Up to 72% ee was achieved for epoxidation of 3-substituted and cis-disubstituted styrenes by employing 1 as the oxidant, whereas entantioselectivities of only 20-40 % were obtained in the reactions with 2-substituted and trans-disubstituted styrenes. Complex 2a oxidized 2-substituted styrenes to their epoxides in up to 88% ee. Its reactions with transalkenes are more enantioselective (67 % ee) than with the cis-alkenes (40 % ee). Based on a two-dimensional NOESY NMR study, 2a was found to adopt a more open conformation in benzene than in dichloromethane, which explains the observed solvent-dependent enantioselectivity of its reactions with alkenes. The oxidation of aromatic alkenes by the chiral dioxoruthenium(VI) porphyrins proceeds through the ratelimiting formation of a benzylic radical intermediate; the observed enantioselectivity (eeobs) depends on both the facial selectivity of the first C-O bond formation step and the diastereoselectivity of the subsequent epoxide ring closure. To account for the observed facial selection, "side-on" and "top-on" approach transition state models are examined (see: B. D. Brandes, E. N. Jacobsen, Tetrahedron Lett. 1995, 36, 5123).
- Zhang, Rui,Yu, Wing-Yiu,Sun, Hong-Zhe,Liu, Wei-Sheng,Che, Chi-Ming
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p. 2495 - 2507
(2007/10/03)
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- Aralkylation of guanosine with para-substituted styrene oxides
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To probe mechanisms of nucleoside aralkylation, product distributions and product stereochemistries were determined in reactions of optically active p-methyl- and p-bromostyrene oxide with guanosine. The proportion of 7-, N2-, and O6
- Barlow, Thomas,Dipple, Anthony
-
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- Remarkable Effects of Metal, Solvent, and Oxidant on Metalloporphyrin-Catalyzed Enantioselective Epoxidation of Olefins
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Three metal complexes of one particular homochiral porphyrin were investigated as catalysts for enantioselective epoxidation of unfunctionalized olefins under various reaction conditions. Much better results were obtained with the iron and ruthenium compl
- Gross, Zeev,Ini, Santiago
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p. 5514 - 5521
(2007/10/03)
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- Microbiological transformations. 33. Fungal epoxide hydrolases applied to the synthesis of enantiopure para-substituted styrene oxides. A mechanistic approach
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The biohydrolysis of differently para-substituted styrene oxide derivatives was studied, using whole cells of the fungi Aspergillus niger or Beauveria sulfurescens. These microorganisms proved to be equipped with epoxide hydrolases which are able to achieve these hydrolyses with high enantioselectivity. This allowed the preparation of the optically active epoxides and of the corresponding vicinal diols which were obtained with good to excellent enantiomeric purity. These two microorganisms proved to be enantiocomplementary. A mechanistic study, carried out using a crude lyophilized enzymatic extract from A. niger, indicated via Hammet coefficient plotting that this hydrolysis is very probably due to a general base-catalyzed process.
- Pedragosa-Moreau,Morisseau,Zylber,Archelas,Baratti,Furstoss
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p. 7402 - 7407
(2007/10/03)
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- Enantioselective Epoxidation of Styrene Derivatives by Chloroperoxidase Catalysis
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Chloroperoxidase catalysed epoxidation of styrene derivatives by t-BuOOH preferentially gives (R) oxides with ee values between 28 and 68percent.The data support the view of oxygen delivery from the ferryl oxygen directly to the substrate.
- Colonna, Stefano,Gaggero, Nicoletta,Casella, Luigi,Carrea, Giacomo,Pasta, Piero
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p. 1325 - 1330
(2007/10/02)
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