- Efficient and selective peracetic acid epoxidation catalyzed by a robust manganese catalyst
-
(Chemical Equation Presented) A manganese catalyst containing a tetradentate ligand derived from triazacyclononane exhibits high catalytic activity in epoxidation reactions using peracetic acid as oxidant. The system exhibits broad substrate scope and requires small (0.1-0.15 mol %) catalyst loading. The catalyst is remarkably selective toward aliphatic cis-olefins. Mechanistic studies point toward an electrophilic oxidant delivering the oxygen atom in a concerted step.
- Garcia-Bosch, Isaac,Company, Anna,Fontrodona, Xavier,Ribas, Xavi,Costas, Miquel
-
-
Read Online
- Photoreaction of cinnamate with nitrogen monoxide catalyzed by metallosalen complexes
-
Ethyl cinnamate was allowed to react with nitrogen monoxide (NO) by photoirradiation in the presence of metallosalen complexes (4), oxygen, and axial ligands for 4 to yield furoxan derivatives (6). Oxygen and axial ligands are indispensable for this react
- Furusho, Yoshio,Sohgawa, Yow-hei,Kihara, Nobuhiro,Takata, Toshikazu
-
-
Read Online
- Dioxiranes: Synthesis and Reactions of Methyldioxiranes
-
The peroxymonosulfate-acetone system produces dimethyldioxirane under conditions permitting distillation of the dioxirane from the synthesis vessel.The same conditions were used to prepare other methyldioxiranes.Solutions of dimethyldioxirane prepared in this manner were used to study its chemical and spectroscopic properties.The caroate-acetone system was also used to study the chemistry of in situ generated dimethyldioxirane.
- Murray, Robert W.,Jeyaraman, Ramasubbu
-
-
Read Online
- Metal-free ring-opening of epoxides with potassium trifluoroborates
-
The ring-opening of epoxides with potassium trifluoroborates proceeds smoothly in the presence of trifluoroacetic anhydride under metal-free conditions. The reactions are regioselective and afford a single diastereomer. Both electron-rich and electron-poor aryltrifluoroborates are tolerated.
- Roscales, Silvia,Csaky, Aurelio G.
-
-
Read Online
- SELECTIVE INHIBITORS OF NLRP3 INFLAMMASOME
-
The present disclosure relates to compounds of Formula (I): (I); and to their pharmaceutically acceptable salts, pharmaceutical compositions, methods of use, and methods for their preparation. The compounds disclosed herein are useful for inhibiting the maturation of cytokines of the IL-1 family by inhibiting inflammasomes and may be used in the treatment of disorders in which inflammasome activity is implicated, such as autoinflammatory and autoimmune diseases and cancers.
- -
-
Paragraph 0465; 0484; 0491
(2019/02/15)
-
- Hypervalent Iodine(III)-Catalyzed Epoxidation of β-Cyanostyrenes
-
A convenient approach for the synthesis of β-cyanoepoxides is illustrated by iodine(III)-catalyzed epoxidation of electron-deficient β-cyanostyrenes, wherein the active catalytic iodine(III) species was generated in situ. The epoxidation of β-cyanostyrenes was performed using 10 molpercent PhI as precatalyst in the presence of 2.0 equivalents Oxone as an oxidant and 2.4 equivalents of TFA as an additive at room temperature under ultrasonic radiations. The β-cyanoepoxides were isolated in good to excellent yields in a short reaction time.
- Mangaonkar, Saeesh R.,Singh, Fateh V.
-
p. 4473 - 4486
(2019/11/21)
-
- CERAMIDE GALACTOSYLTRANSFERASE INHIBITORS FOR THE TREATMENT OF DISEASE
-
Described herein are compounds, methods of making such compounds, pharmaceutical compositions and medicaments containing such compounds, and methods of using such compounds to treat or prevent diseases or disorders associated with the enzyme ceramide galactosyltransferase (CGT), such as, for example, lysosomal storage diseases. Examples of lysosomal storage diseases include, for example, Krabbe disease and Metachromatic Leukodystrophy.
- -
-
Paragraph 000578; 000579; 000960; 000961
(2018/01/17)
-
- Bioinspired Manganese Complexes and Graphene Oxide Synergistically Catalyzed Asymmetric Epoxidation of Olefins with Aqueous Hydrogen Peroxide
-
Bioinspired manganese complexes of N4ligands and graphene oxide (GO) synergistically catalyze the highly enantioselective epoxidation of olefins (up to 99% ee), which is a rare example with GO as a co-catalyst in asymmetric catalysis. GO as a new and key additive not only successfully functions in catalytic amounts, but also has a positive effect for improving the enantioselectivity of the asymmetric epoxidation compared with the traditional stoichiometric organic carboxylic acid method [e.g., chalcone, 95% ee (3.5 mg GO) vs. 84% ee (5 equiv., 75 mg acetic acid), ethyl cinnamate, 84% ee (3.5 mg GO) vs. 19% ee (5 equiv., 75 mg acetic acid)]. The X-ray photoelectron spectroscopy (XPS) spectra of GO before and after the reaction indicate that the intensities of C–O become stronger after the reaction, which may have a certain relationship with hydrogen peroxide (H2O2) and gives a reasonable rationale for the large consumption of H2O2. Also, part of the hydrogen peroxide was used for the oxidation of GO. (Figure presented.).
- Miao, Chengxia,Yan, Xingbin,Xu, Daqian,Xia, Chungu,Sun, Wei
-
p. 476 - 484
(2017/02/10)
-
- Enantioselective bio-hydrolysis of various racemic and meso aromatic epoxides using the recombinant epoxide hydrolase Kau2
-
Abstract Epoxide hydrolase Kau2 overexpressed in Escherichia coli RE3 has been tested with ten different racemic and meso α,β-disubstituted aromatic epoxides. Some of the tested substrates were bi-functional, and most of them are very useful building blocks in synthetic chemistry applications. As a general trend Kau2 proved to be an extremely enantioselective biocatalyst, the diol products and remaining epoxides of the bioconversions being obtained - with two exceptions - in nearly enantiomerically pure form. Furthermore, the reaction times were usually very short (around 1 h, except when stilbene oxides were used), and the use of organic co-solvents was well tolerated, enabling very high substrate concentrations (up to 75 g/L) to be reached. Even extremely sterically demanding epoxides such as cis- and trans-stilbene oxides were transformed on a reasonable time scale. All reactions were successfully conducted on a 1 g preparative scale, generating diol- and epoxide-based chiral synthons with very high enantiomeric excesses and isolated yields close to the theoretical maximum. Thus we have here demonstrated the usefulness and versatility of lyophilized Escherichia coli cells expressing Kau2 epoxide hydrolase as a highly enantioselective biocatalyst for accessing very valuable optically pure aromatic epoxides and diols through kinetic resolution of racemates or desymmetrization of meso epoxides.
- Zhao, Wei,Kotik, Michael,Iacazio, Gilles,Archelas, Alain
-
p. 1895 - 1908
(2015/06/02)
-
- A novel enantioselective epoxide hydrolase from Agromyces mediolanus ZJB120203: Cloning, characterization and application
-
A new strain Agromyces mediolanus ZJB120203, capable of enantioselective epoxide hydrolase (EH) activity was isolated employing a newly established colorimetric screening and chiral GC analysis method. The partial nucleotide sequence of an epoxide hydrolase (AmEH) gene from A. mediolanus ZJB120203 was obtained by PCR using degenerate primers designed based on the conserved domains of EHs. Subsequently, an open reading frame containing 1167 bp and encoding 388 amino acids polypeptide were identified. Expression of AmEH was carried out in Escherichia coli and purification was performed by Nickel-affinity chromatography. The purified AmEH had a molecular weight of 43 kDa and showed its optimum pH and temperature at 8.0 and 35 C, respectively. Moreover, this AmEH showed broad substrates specificity toward epoxides. In this study, it is demonstrated that the AmEH could unusually catalyze the hydrolysis of (R)-ECH to produce enantiopure (S)-ECH. Enantiopure (S)-ECH could be obtained with enantiomeric excess (ee) of >99% and yield of 21.5% from 64 mM (R,S)-ECH. It is indicated that AmEH from A. mediolanus is an attractive biocatalyst for the efficient preparation of optically active ECH.
- Xue, Feng,Liu, Zhi-Qiang,Zou, Shu-Ping,Wan, Nan-Wei,Zhu, Wen-Yuan,Zhu, Qing,Zheng, Yu-Guo
-
p. 409 - 417
(2014/04/03)
-
- Method for Preparing Optically Pure (-)-Clausenamide Compound
-
Disclosed in the present invention is a method for preparing a (?)-clausenamide compound of formula (I), comprising: firstly, catalyzing the asymmetrical epoxidation of trans-cinnamate using a chiral ketone derived from fructose or a hydrate thereof as a catalyst, and then subjecting the product to transesterification, oxidation, cyclization and reduction successively to finally obtain the optically pure (?)-clausenamide compound of formula (I).
- -
-
Paragraph 0042; 0043; 0044; 0045
(2014/07/23)
-
- A mononuclear manganese complex of a tetradentate nitrogen ligand - Synthesis, characterizations, and application in the asymmetric epoxidation of olefins
-
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)
-
- Asymmetric epoxidation with H2O2 by manipulating the electronic properties of non-heme iron catalysts
-
A non-heme iron complex that catalyzes highly enantioselective epoxidation of olefins with H2O2 is described. Improvement of enantiomeric excesses is attained by the use of catalytic amounts of carboxylic acid additives. Electronic effects imposed by the ligand on the iron center are shown to synergistically cooperate with catalytic amounts of carboxylic acids in promoting efficient O-O cleavage and creating highly chemo-and enantioselective epoxidizing species which provide a broad range of epoxides in synthetically valuable yields and short reaction times.
- Cusso, Olaf,Garcia-Bosch, Isaac,Ribas, Xavi,Lloret-Fillol, Julio,Costas, Miquel
-
supporting information
p. 14871 - 14878
(2013/10/22)
-
- Selective catalytic oxidation of alcohols, aldehydes, alkanes and alkenes employing manganese catalysts and hydrogen peroxide
-
The manganese-containing catalytic system [MnIV,IV 2O3(tmtacn)2]2+ (1)/carboxylic acid (where tmtacn=N,N′,N′′-trimethyl-1,4,7-triazacyclononane), initially identified for the cis-dihydroxylation and epoxidation of alkenes, is applied for a wide range of oxidative transformations, including oxidation of alkanes, alcohols and aldehydes employing H2O2 as oxidant. The substrate classes examined include primary and secondary aliphatic and aromatic alcohols, aldehydes, and alkenes. The emphasis is not primarily on identifying optimum conditions for each individual substrate, but understanding the various factors that affect the reactivity of the Mn-tmtacn catalytic system and to explore which functional groups are oxidised preferentially. This catalytic system, of which the reactivity can be tuned by variation of the carboxylato ligands of the in situ formed [MnIII,III 2(O)(RCO2)2(tmtacn)2]2+ dimers, employs H2O2 in a highly atom efficient manner. In addition, several substrates containing more than one oxidation sensitive group could be oxidised selectively, in certain cases even in the absence of protecting groups. Copyright
- Saisaha, Pattama,Buettner, Lea,Van Der Meer, Margarethe,Hage, Ronald,Feringa, Ben L.,Browne, Wesley R.,De Boer, Johannes W.
-
supporting information
p. 2591 - 2603
(2013/10/21)
-
- Four metalloporphyrinic frameworks as heterogeneous catalysts for selective oxidation and aldol reaction
-
Four porous metalloporphyrinic framework materials, [(CH3) 2NH2][Zn2(HCOO)2(Mn III-TCPP)]·5DMF·2H2O (1; H6TCPP = tetrakis(4-carboxyphenyl)porphyrin), [(CH3)2NH 2][Cd2(HCOO)2(MnIII-TCPP)] ·5DMF·3H2O (2), [Zn2(HCOO)(Fe III(H2O)-TCPP)]·3DMF·H2O (3), and [Cd3(H2O)6(μ2-O)(Fe III-HTCPP)2]·5DMF (4) were synthesized by heating a mixture of MIIICl-H4TCPP (M = Mn and Fe) and M′ (M′ = Zn or Cd) nitrate in a mixed solvent of DMF and acetic acid. Compounds 1-3 are built up from M′2(COO)4 paddle-wheel subunits bridged by MIII-TCPP and formate ligands to form their 3D connections. The formate pillar heterogeneously connects with M and M′ cations in 1 and 2 and homogeneously joins M′ cations in 3. The μ2-O bridged FeIII-HTCPP dimer performs as a decadentate ligand to link 10 cadmium cations for the formation of an interesting 3D coordination network of 4. The four porphyrinic frameworks present interesting catalytic properties in the selective epoxidation of olefins, oxidation of cyclohexane, and intermolecular aldol reaction of aldehydes and ketones.
- Zou, Chao,Zhang, Tianfu,Xie, Ming-Hua,Yan, Lijun,Kong, Guo-Qiang,Yang, Xiu-Li,Ma, An,Wu, Chuan-De
-
p. 3620 - 3626
(2013/05/09)
-
- A sandwich N-doped graphene/Co3O4 hybrid: An efficient catalyst for selective oxidation of olefins and alcohols
-
A sandwich-like N-doped graphene/Co3O4 hybrid was prepared via a simple one-pot hydrothermal reaction in a solution of NH 3. Characterizations disclosed that highly dispersed Co 3O4 nanoparticles with dominant exposed {112} and {110} planes were fabricated on both sides of well-exfoliated N-doped graphene; N-dopants in the graphene matrix can prevent re-graphitization of graphene, strengthen the interaction between Co3O4 and the graphene matrix, and improve the dispersion of Co3O4. This hybrid (Co3O4/RGO-N) exhibited superior activity and stability for the epoxidation of styrene compared to bulk Co3O 4 and N-free graphene supported Co3O4. At the same time, the resulting catalyst also showed high compatibility with various olefins and alcohols with good conversion and high selectivity. This synergistic strategy can provide simple, efficient and versatile blue-prints for low-cost fabrication of graphene-based nanocomposites for extending applications where graphene has rarely been exploited and beyond.
- Nie, Renfeng,Shi, Juanjuan,Du, Weichen,Ning, Wensheng,Hou, Zhaoyin,Xiao, Feng-Shou
-
p. 9037 - 9045
(2013/09/23)
-
- BOROX catalysis: Self-assembled AMINO-BOROX and IMINO-BOROX chiral Bronsted acids in a five component catalyst assembly/ catalytic asymmetric aziridination
-
A five-component catalyst assembly/aziridination reaction is described starting from an aldehyde, an amine, ethyl diazoacetate, B(OPh)3, and a molecule of a vaulted biaryl ligand (VAPOL or VANOL). A remarkable level of chemoselectivity was observed since, while 10 different products could have resulted from various reactions between the five components, an aziridine was formed in 85% yield and 98% ee and only two other products could be detected in 3% yield. Studies reveal that the first in a sequence of three reactions is an exceedingly rapid amine-induced assembly of an AMINOBOROX chiral Bronsted acid species from VAPOL and B(OPh)3, which is followed by imine formation from the amine and aldehyde and the concomitant formation of an IMINO-BOROX chiral Bronsted acid and finally the reaction of the imine with ethyl diazoacetate mediated by the IMINO-BOROX catalyst to give aziridine-2-carboxylic esters with very high diastereo- and enantioselectivity.
- Gupta, Anil K.,Mukherjee, Munmun,Hu, Gang,Wulff, William D.
-
supporting information
p. 7932 - 7944,13
(2020/10/15)
-
- 3- and 4-uloses derived from N-acetyl- D -glucosamine: A unique pair of complementary organocatalysts for asymmetric epoxidation of alkenes
-
The 4-ulose and the 3-ulose, both derived in two steps from the α-methyl glycoside of N-acetyl-D-glucosamine (GlcNAc), act as organocatalysts in the asymmetric epoxidation of alkenes, with unprecedented complementary enantioselectivity. The best results are found with α,β-unsaturated esters as substrates, with enantiomeric ratios up to 90:10 and 11:89, respectively. Copyright
- Schoeberl, Christof,Jaeger, Volker
-
supporting information; experimental part
p. 790 - 796
(2012/05/04)
-
- A new layered metal-organic framework as a promising heterogeneous catalyst for olefin epoxidation reactions
-
A new layered MOF material [Co(Hoba)2·2H2O] (1) (H2oba = 4,4′-oxybis(benzoic acid)) has been synthesized and used as a highly recyclable heterogeneous catalyst for olefin epoxidation reactions. Both high conversion (96%) and high selectivity of epoxide products (96%) are achieved.
- Zhang, Jingming,Biradar, Ankush V.,Pramanik, Sanhita,Emge, Thomas J.,Asefa, Tewodros,Li, Jing
-
supporting information; experimental part
p. 6541 - 6543
(2012/07/30)
-
- PROCESS FOR MAKING AND USING HOF.RCN
-
The invention relates to a process for making HOF.RCN and using it to oxidise organic substrates in a quick and safe way. The process comprises passing diluted fluorine through a conduit and RCN in water through another conduit into a microreactor to form HOF.RCN and reacting this with an organic substrates.
- -
-
Page/Page column 7
(2011/04/14)
-
- Catalytic enantioselective alkene epoxidation using novel spirocyclic N-carbethoxy-azabicyclo[3.2.1]octanones
-
A general synthetic route allowing access to several spirocyclic N-carbethoxy-azabicyclo[3.2.1]octanones is developed. These novel ketones efficiently catalyse alkene epoxidation using Oxone with up to 91.5% ee.
- Armstrong, Alan,Bettati, Michela,White, Andrew J.P.
-
experimental part
p. 6309 - 6320
(2010/10/19)
-
- A facile Ph3P/CO2 mediated, one-pot synthesis of 2-oxazolidinones from 1, 2-azido alcohols via phosphazene and isocyanate intermediates
-
A facile, efficient and convenient method has been developed for the one-pot synthesis of 2-oxazolidinones from the corresponding 1, 2-azido alcohols via phosphazene and isocyanate intermediates in presence of Ph 3P/CO2 in toluene.
- Madhusudhan,Reddy, M. Srinivasa,Reddy, Y. Narayana,Vijayalakshmi,Suribabu,Balraju
-
body text
p. 978 - 984
(2010/10/19)
-
- Asymmetric counteranion-directed transition-metal catalysis: Enantioselective epoxidation of alkenes with Manganese(III) salen phosphate complexes
-
(Figure Presented) Figure Presentation Paired up: A highly active and enantioselective ion-pair epoxidation catalyst, consisting of an achiral Mn |||-salen complex and a chiral phosphate counteranion, mediates the epoxidization of a wide range of alkenes with high yields and enantioselectivities (see scheme). The unique role of the counteranion is to stabilize an enantiomorphic conformation of the cationic Mn catalyst.
- Liao, Saihu,List, Benjamin
-
supporting information; experimental part
p. 628 - 631
(2010/04/06)
-
- Manganese catalyzed cis-dihydroxylation of electron deficient alkenes with H2O2
-
A practical method for the multigram scale selective cis-dihydroxylation of electron deficient alkenes such as diethyl fumarate and N-alkyl and N-aryl-maleimides using H2O2 is described. High turnovers (>1000) can be achieved with this efficient manganese based catalyst system, prepared in situ from a manganese salt, pyridine-2-carboxylic acid, a ketone and a base, under ambient conditions. Under optimized conditions, for diethyl fumarate at least 1000 turnovers could be achieved with only 1.5 equiv. of H2O2 with d/l-diethyl tartrate (cis-diol product) as the sole product. For electron rich alkenes, such as cis-cyclooctene, this catalyst provides for efficient epoxidation.
- Saisaha, Pattama,Pijper, Dirk,Van Summeren, Ruben P.,Hoen, Rob,Smit, Christian,De Boer, Johannes W.,Hage, Ronald,Alsters, Paul L.,Feringa, Ben L.,Browne, Wesley R.
-
supporting information; experimental part
p. 4444 - 4450
(2010/11/05)
-
- Novel polyaniline supported cobalt catalyzed aerobic oxidation of unsaturated organic compounds
-
The oxidation of organic compounds with carbon-carbon double bond with molecular oxygen under atmospheric pressure in the presence of new polyaniline supported catalyst 1 has been studied. This catalyst turned out to be efficient and selective for oxidation of some unsaturated organic compounds. Oxidation of alkenes, cycloalkenes and terpenes give corresponding epoxy derivatives, whereas organic compounds with carbon carbon double bond in benzylic position give ketones as a main product. Taylor & Francis Group, LLC.
- Pielichowski, Jan,Kowalski, Grzegorz
-
experimental part
p. 105 - 111
(2011/08/03)
-
- Malodour reducing composition and uses thereof
-
The invention relates to a malodour reducing composition comprising: A) at least one phenylglycidate of formula (1): wherein: - R1 is a C1-C4 branched or linear alkyl group, - R2 is hydrogen or methyl, and - R3 is hydrogen, a C1-C4 branched or linear alkyl group or a methoxy group, and B) at least one 1,2 diketone of formula (2) or (3): wherein: - R4, R5 and R7 may be independently, a C1-C5 linear or branched alkyl or alkenyl group; - R6 is a (C1-C5) alkylidene; - R4 and R5 may also form a C4-C7 saturated or unsaturated alicyclic or heterocyclic ring structure, optionally substituted by (C1-C4) alkyl groups; - R6 and R7 may also form a C4-C7 unsaturated, alicyclic or heterocyclic ring structure optionally substituted by (C1-C4) alkyl groups; the weight ratio of glycidate A to 1,2 diketone B being from 1:99 to 99:1. The invention also relates to the fragrance compositions and consumer products containing this malodour reducing composition.
- -
-
-
- Manganese-promoted regioselective ring-opening of 2,3-epoxy acid derivatives: a new route to α-hydroxy acid derivatives
-
A simple and general methodology directed towards the synthesis 3-aryl-2-hydroxy amides, or esters with total regioselectivity from the easily available 2,3-epoxy amides or esters, promoted by active manganese is described. Utilizing enantiopure epoxy amides as starting materials, the corresponding 3-aryl-2-hydroxy amides in enantiopure form are also available. Some synthetic applications of selected examples of 3-aryl-2-hydroxy carboxylic acid derivatives are shown. A mechanism has been proposed to explain this novel reaction.
- Concellon, Jose M.,Bernad, Pablo L.,Rodriguez-Solla, Humberto,Diaz, Pamela
-
experimental part
p. 2178 - 2184
(2009/12/31)
-
- A diacetate ketone-catalyzed asymmetric epoxidation of olefins
-
(Chemical Equation Presented) A fructose-derived diacetate ketone has been shown to be an effective catalyst for asymmetric epoxidation. High ee values have been obtained for a variety of trans and trisubstituted olefins including electron-deficient α,β-unsaturated esters as well as certain cis olefins.
- Wang, Bin,Wu, Xin-Yan,Wong, O. Andrea,Nettles, Brian,Zhao, Mei-Xin,Chen, Dajun,Shi, Yian
-
experimental part
p. 3986 - 3989
(2009/09/30)
-
- Homogeneous epoxidation of lipophilic alkenes by aqueous hydrogen peroxide: Catalysis of a Keggin-type phosphotungstate-functionalized ionic liquid in amphipathic ionic liquid solution
-
The ionic liquid compositions (ILC) composed of the Keggin-type phosphotungstate-functionalized ionic liquid of [Dopy]3[PW 12O40] (1) and the amphipathic IL mixture of [Bpy]BF 4 and [Dopy]BF4, were constructed as an effective catalytic system and ideal reaction medium for alkene epoxidation by aqueous H2O2, in which the real homogeneous catalysis was fulfilled with advantages of high activity, simplified work-up and available recyclability. The designing concept of the ILC and the IL effect on the activity/stability were discussed herein. The Royal Society of Chemistry 2009.
- Wang, Sa-Sa,Liu, Wei,Wan, Qing-Xia,Liu, Ye
-
scheme or table
p. 1589 - 1594
(2010/06/13)
-
- Gelozymes in organic synthesis. Part IV: Resolution of glycidate esters with crude Mung bean (Phaseolus radiatus) epoxide hydrolase immobilized in gelatin matrix
-
A crude extract of Mung bean meal (Phaseolus radiatus) possessing epoxide hydrolase activity immobilized in gelatin gel (gelozyme) is employed in the stereoselective epoxide ring opening of glycidate esters. Thus, ethyl trans-(±)-3-phenyl glycidate 1a and methyl trans-(±)-3-(4-methoxyphenyl) glycidate 1b gave (2S,3R)-glycidate esters (ee >99% and 45% yield) with gelatin immobilized enzyme in diisopropyl ether. The corresponding (2R,3S)-enantiomer of 1a was hydrolyzed by an epoxide hydrolase to predominantly give the anti-product, ethyl (2R,3R)-2,3-dihydroxy-3-phenylpropanoate, with a diastereomeric excess of 78% and ee 94% (40%). A small amount (5%) of racemic syn-product was also obtained as a result of the spontaneous hydrolysis. In the case of 1b, the hydrolysis product was racemic due to high reactivity of the glycidate toward water.
- Devi, Avala Vedamayee,Lahari, Challa,Swarnalatha, Lakshmi,Fadnavis
-
p. 1139 - 1144
(2008/09/20)
-
- Design and characterization of mechanism-based inhibitors for the tyrosine aminomutase SgTAM
-
The synthesis and evaluation of two classes of inhibitors for SgTAM, a 4-methylideneimidazole-5-one (MIO) containing tyrosine aminomutase, are described. A mechanism-based strategy was used to design analogs that mimic the substrate or product of the reaction and form covalent interactions with the enzyme through the MIO prosthetic group. The analogs were characterized by measuring inhibition constants and X-ray crystallographic structural analysis of the co-complexes bound to the aminomutase, SgTAM.
- Montavon, Timothy J.,Christianson, Carl V.,Festin, Grace M.,Shen, Ben,Bruner, Steven D.
-
p. 3099 - 3102
(2008/12/22)
-
- Mild oxidation of styrene and its derivatives with ionic manganese porphyrin immobilized in the similarly structured ionic liquid
-
Without the auxiliary involvement of axial ligands and organic solvents, the ionic manganese porphyrin 1c immobilized in [BPy][BF4] efficiently catalyzed the oxidation of styrene and its derivatives under mild conditions, affording high activity/oxide selectivity and good stability even after 5 recycling uses. Copyright
- Liu, Ye,Zhang, Hong-Jiao,Cai, Yue-Qin,Wu, Hai-Hong,Liu, Xiu-Li,Lu, Yong
-
p. 848 - 849
(2008/02/12)
-
- Catalytic investigations of calix[4]arene scaffold based phase transfer catalyst
-
Calix[4]arene scaffold based quaternary ammonium salts as multi-site phase transfer catalysts were prepared and their catalytic activities were investigated for Darzens condensation, O/N-alkylation reactions and ethyl benzene oxidation. These calix[4]arene based multi-site phase transfer catalysts showed significant high catalytic activity as compared to single-site phase transfer catalysts.
- Srivastava, Pallavi,Srivastava, Rajendra
-
p. 4489 - 4493
(2008/02/03)
-
- Epoxidation and oxidation reactions using divinyl benzene crosslinked polystyrene supported t-butyl hydroperoxide
-
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
-
p. 943 - 950
(2007/10/03)
-
- Dichlororuthenium(IV) complex of meso-Tetrakis(2,6-dichlorophenyl) porphyrin: Active and robust catalyst for highly selective oxidation of arenes, Unsaturated steroids, and electron-deficient alkenes by using 2,6-dichloropyridine N-oxide
-
[RuIV(2,6-Cl2tpp)Cl2], prepared in 90% yield from the reaction of [RuVI(2,6-Cl2tpp)O2] with Me3SiCl and structurally characterized by X-ray crystallography, is markedly superior to [RuIv(tmp)Cl2], [RuIV(ttp)Cl2], and [RuII(por)(CO)] (por = 2,6-Cl2tpp, F20-tpp, F28-tpp) as a catalyst for alkene epoxidation with 2,6-Cl2pyNO (2,6Cl2tpp = meso-tetrakis(2,6-dichlorophenyl)porphyrinato dianion; tmp = meso-tetramesitylporphyrinato dianion; ttp = meso-tetrakis(p-tolyl)porphyrinato dianion; F20-tpp = meso-tetrakis(pentafluorophenyl)porphyrinato dianion; F28-tpp = 2,3,7,8,12,13,17,18-octafluoro-5,10,15,20- tetrakis(pentafluorophenyl)-porphyrinato dianion). The "[Ru IV(2,6-Cl2tpp)Cl2] + 2,6-Cl 2pyNO" protocol oxidized, under acid-free conditions, a wide variety of hydrocarbons including 1) cycloalkenes, conjugated enynes, electron-deficient alkenes (to afford epoxides), 2) arenes (to afford quinones), and 3) Δ5-unsaturated steroids, Δ4-3- ketosteroids, and estratetraene derivatives (to afford epoxide/ketone derivatives of steroids) in up to 99% product yield within several hours with up to 100% substrate conversion and excellent regio- or diastereoselectivity. Catalyst [RuIv(2,6-Cl2tpp)Cl2] is remarkably active and robust toward the above oxidation reactions, and turnover numbers of up to 6.4 × 103, 2.0 × 104, and 1.6 × 104 were obtained for the oxidation of α,β-unsaturated ketones, arenes, and Δ5-unsaturated steroids, respectively.
- Zhang, Jun-Long,Che, Chi-Ming
-
p. 3899 - 3914
(2007/10/03)
-
- An improved catalytic system for recycling OsO4 and chiral ligands in the asymmetric dihydroxylation of olefins
-
A recyclable catalytic system for the asymmetric dihydroxylation of olefins was developed by using a mono-quaternized bis-cinchona alkaloid ligand 3 and OsO4 combined with PEG or an ionic liquid. Both the catalytic components could be recovered and reused in five consecutive reactions without any additional OsO4 or ligand. The catalytic system is effective in the AD reactions of seven olefins.
- Jiang, Ru,Kuang, Yongqing,Sun, Xiaoli,Zhang, Shengyong
-
p. 743 - 746
(2007/10/03)
-
- Studies on synthesis and anti-bacterial activity of novel 4-substituted phenyl-2-oxo-1,3-oxazolidine-5-carboxylates
-
Regioselective opening of glycidic esters with sodium azide gives azido alcohols, which are converted to novel 4-substituted phenyl-2-oxo-1, 3-oxazolidine-5-carboxylates by various methods. These compounds are tested for in vitro anti-bacterial activity against Staphylococcus aureous, E. faecalis and E. faecium.
- Madhusudha,Om Reddy,Ramatham,Dubey
-
p. 957 - 963
(2007/10/03)
-
- PROCESS FOR THE PRODUCTION OF ASYMMETRIC EPOXIDES UNDER NON-AQUEOUS CONDITIONS AND CATALYTIC COMPOSITION FOR USE THEREIN
-
A process for the asymmetric epoxidation of α,β-unsaturated carbonyl or sulphonyl compounds comprising : providing, in the absence of an aqueous phase, a catalyst/reagent composition comprising a poly-amino acid catalyst effective for catalysing the asymmetric epoxidation reaction, the poly-amino acid catalyst encapsulating an expoxidation reagent effective for epoxidation of α,β-unsaturated carbonyl or sulphonyl compounds; contacting the catalyst/reagent composition with an α,β-unsaturated carbonyl or sulphonyl compound substrate under conditions effective to provide at least partial asymmetric epoxidation of the substrate by the epoxidation reagent; and recovering the resulting asymmetric epoxide.
- -
-
Page 9; 12; 14
(2008/06/13)
-
- Chemoenzymatic approach to optically active phenylglycidates: Resolution of bromo- and iodohydrins
-
Enantiomerically enriched phenylglycidates, precursors of the taxol C-13 phenylisoserine side chain and diltiazem, were prepared by kinetic resolution of anti-2-bromo-3-hydroxy- and anti-3-hydroxy-2-iodophenylpropanoates to provide enantioriched (2R,3R)- and (2S,3S)-halohydrins. The bulkiness and inflexibility of bromo and iodo groups in halohydrins have made them inaccessible to the active site of most of the lipases utilized for the hydrolysis of their acyloxy derivatives. In a set of 22 hydrolases screened herein, including native as well as commercial enzymes, only Aspergillus niger (Lipase AS, AMANO) could catalyze the hydrolysis with high enantioselectivity (E = 176). The resolved halohydrins easily underwent transformation to the corresponding (2S,3R)- and (2R,3S)-phenylglycidates.
- Anand, Naveen,Kapoor, Munish,Koul, Surrinder,Taneja, Subhash C.,Sharma, Rattan L.,Qazi, Ghulam N.
-
p. 3131 - 3138
(2007/10/03)
-
- Synthesis of the spermidine alkaloids (-)-(2R,3R)- and (-)-(2R,3S)-3-hydroxycelacinnine: Macrocyclization with oxirane-ring opening and inversion via cyclic sulfamidates
-
The two epimers (-)-1a and (-)-1b of the macrocyclic lactama kaloid 3-hydroxycelacinnine with the (2R,3R) and (2R,3S) absolute configurations, respectively, were synthesized by an alternative route involving macrocyclization with the regio- and stereoselective oxirane-ring opening by the terminal amino group (Schemes 2 and 6). Properly N-protected chiral trans-oxirane precursors provided (2R,3R)-macrocycles after a one-pot deprotection-macrocyclization step under moderate dilution (0.005-0.01M). The best yields (65-85%) were achieved with trifluoroacetyl protection. Macrocyclization of the corresponding cis-oxiranes was unsuccessful for steric reasons. Inversion at OH-C(3) via nucleophilic displacement of the cyclic sulfamidate derivative with NaNO2 led to (2R,3S)-macrocycles. The synthesized (-)-(2R,3S)-3-hydroxycelacinnine ((-)-1b) was identical to the natural alkaloid.
- Khanjin, Nikolai A.,Hesse, Manfred
-
p. 2028 - 2057
(2007/10/03)
-
- Catalytic asymmetric epoxidation of α,β-unsaturated carboxylic acid imidazolides and amides by lanthanide-BINOL complexes
-
Highly enantioselective catalytic asymmetric epoxidation of α,β-unsaturated carboxylic acid imidazolides and simple amides was developed. In the presence of 5-10mol% of lanthanide-BINOL complexes, the reaction proceeded smoothly with high substrate generality. In particular, in the cases of α,β-unsaturated amides, there was nearly perfect enantioselectivity (>99% ee). The corresponding epoxides were successfully transformed into many types of useful chiral compounds such as α,β-epoxy esters, α,β-epoxy amides, α,β-epoxy aldehydes, α,β-epoxy β-keto ester, and α- and β-hydroxy carbonyl compounds. B3LYP density functional studies were performed to predict substrate reactivity.
- Ohshima, Takashi,Nemoto, Tetsuhiro,Tosaki, Shin-Ya,Kakei, Hiroyuki,Gnanadesikan, Vijay,Shibasaki, Masakatsu
-
p. 10485 - 10497
(2007/10/03)
-
- The first example of an amide-carbonyl stabilized oxiranyl anion: Generation from epoxysilane, its properties, and trapping with electrophiles
-
An epoxysilane having an amide group at the a-carbon was synthesized from phenylacetylene. An amide-carbonyl stabilized oxiranylammonium was generated from the epoxysilane in THF with tetrabutylammonium fluoride (TBAF). The generated oxiranyl anion was found to have enough nucleophilicity with aldehydes to give moderate to good yields of the adducts. In some reactions, the oxiranylammonium was found to be configurationally unstable to give the epimers.
- Satoh, Tsuyoshi,Shimura, Takayuki,Sakai, Ken
-
p. 137 - 147
(2007/10/03)
-
- Enantioselective epoxidation of alkenes catalyzed by 2-fluoro-N-carbethoxytropinone and related tropinone derivatives
-
Several α-substituted N-carbethoxytropinones have been evaluated as catalysts for asymmetric epoxidation of alkenes with Oxone, via a dioxirane intermediate. α-Fluoro-N-carbethoxytropinone (2) has been studied in detail and is an efficient catalyst which does not suffer from Baeyer-Villiger decomposition and can be used in relatively low loadings. This ketone was prepared in enantiomerically pure form using chiral base desymmetrization of N-carbethoxytropinone. Asymmetric epoxidation catalyzed by 2 affords epoxides with up to 83% ee. Among other derivatives tested, the α-acetoxy derivative 7 affords the highest enantioselectivities.
- Armstrong, Alan,Ahmed, Ghafoor,Dominguez-Fernandez, Belen,Hayter, Barry R.,Wailest, J. Steven
-
p. 8610 - 8617
(2007/10/03)
-
- The synthesis of solvent-free glycidic esters from diazoesters and carbonyl compounds catalysed by lanthanide trifiates
-
The results of the reaction between ethyl diazoacetate and carbonyl compounds catalysed by lanthanide triflates are described. Aldehydes, and α-unsubstituted and α-monosubstituted cyclohexanones react to give the selective formation of α,β-epoxy esters (g
- Curini, Massimo,Epifano, Francesco,Marcotullio, Maria Carla,Rosati, Ornelio
-
p. 1562 - 1565
(2007/10/03)
-
- Highly enantioselective epoxidation of α,β-unsaturated esters by chiral dioxirane
-
This paper describes a highly enantioselective epoxidation of α,β-unsaturated esters using the fructose-derived ketone 2 as catalyst and Oxone as oxidant. High ee's have been obtained for a number of trans and trisubstituted substrates (82-98% ee). The results described show that it is feasible for dioxiranes to effectively epoxidize electron-deficient olefins with high ee's. Copyright
- Wu, Xin-Yan,She, Xuegong,Shi, Yian
-
p. 8792 - 8793
(2007/10/03)
-
- A Class of C2 and Pseudo C2 Symmetric Ketone Catalysts for Asymmetric Epoxidation. Conformational Effect on Catalysis
-
A class of C2 and pseudo C2 symmetric ketones with one fused ring at each side of the carbonyl group have been prepared from quinic acid and found to be effective catalysts for the asymmetric epoxidation of a variety of olefins. Electron deficient olefins such as enones can be efficiently epoxidized. Encouragingly good enantioselectivity is also obtained for the epoxidation of styrenes. The studies show that the ketone conformation plays an important role in the reactivity and selectivity of the catalyst.
- Wang, Zhi-Xian,Miller, Susie M.,Anderson, Oren P.,Shi, Yian
-
p. 6443 - 6458
(2007/10/03)
-
- Process for the preparation of an oxirane, azirdine or cyclopropane
-
A process for the preparation of an oxirane, aziridine or cyclopropane of formula (I) wherein, X is oxygen, NR4 or CHR5 ; R1 is hydrogen, alkyl, aryl, heteroaromatic, heterocyclic or cycloalkyl; R2 is hydrogen, alkyl, aryl, heteroaromatic, CO2 R8, CHR14 NHR13, heterocyclic or cycloalkyl; or R1 and R2 join together to form a cycloalkyl ring; R3 is hydrogen, alkyl, aryl, heteroaromatic, CO2 R8, R83 Sn, CONR8 R9 or trimethylsilyl; R4 and R5 are, independently, alkyl, cycloalkyl, aryl, heteroaromatic, SO2 R8, SO3 R8, COR8, CO2 R8, CONR8 R9 or CN, or R4 can also be P(O)(aryl)2 ; R8 and R9 are independently alkyl, aryl or arylalkyl; R13 and R14 are independently hydrogen, alkyl or aryl; the process comprising reacting a mixture of a compound of formula (II), wherein R1, R2 and X are as defined above, and a sulphide of formula SR6 R7, wherein R6 and R7 are independently alkyl, aryl or heteroaomatic, or R6 and R7 join together to form a cycloalkyl ring which optionally includes an additional heteroatom, with either (i) a metallocarbon obtainable by reacting an alkylmetal with a methane derivative of formula CHR3 X'X", wherein R3 is as defined above, and X' and X" are independently, a leaving group, or (ii) a metallocarbon obtainable by reacting a compound of formula (III), (wherein R3 may not be hydrogen) with a suitable organometallic or inorganic reagent.
- -
-
-
- A versatile cobalt(II)-Schiff base catalyzed oxidation of organic substrates with dioxygen: Scope and mechanism
-
Cobalt(II) complex 1a-f derived from Schiff bases act as efficient catalysts during the oxidation of wide range of organic substrates(e.g. alkenes, alcohols, benzylic compounds and aliphatic hydrocarbons) with dioxygen in the presence of aliphatic aldehydes or ketones or ketoesters. EPR studies on 1a-f complexes suggest that the aliphatic carbonyl compounds promote the formation of a cobalt(II)-superoxo species responsible for the oxidation of organic compounds. These studies also demonstrate the role of ligands on cobalt in controlling the chemoselectivity of these oxidations. A plausible mechanistic rational is also provided for these oxidations.
- Punniyamurthy,Bhatia, Beena,Reddy, M. Madhava,Maikap, Golak C.,Iqbal, Javed
-
p. 7649 - 7670
(2007/10/03)
-
- Cobalt(II) porphyrin: A versatile catalyst for the oxidation of organic substrates with dioxygen and 2-methyl propanal
-
Cobalt(II)-porphyrin 1 is a versatile catalyst as it promotes the oxidation of wide range of organic substrates at ambient condition by using a combination of molecular oxygen and 2-methyl propanal.
- Mandal,Khanna,Iqbal
-
p. 3769 - 3772
(2007/10/03)
-