5411-12-1Relevant articles and documents
Design and performance of a microstructured peek reactor for continuous poly-l-leucine-catalysed chalcone epoxidation
Kee, Suet-Ping,Gavriilidis, Asterios
, p. 941 - 951 (2009)
The poly-L-leucine (PLL)-catalysed epoxidation of chalcone allows access to highly enantioselective chalcone epoxides. The reaction requires two steps, a deprotonation step where the oxidising reactive species is formed and an epoxidation step where the substrate is epoxidised. In this work, a microstructured SU-8/ PEEK plate flow reactor with a footprint of 110 mm × 85 mm and production rate of ～0.5 g/day was designed. The reactor consists of two micromixer-reactor sections in series. A staggered herringbone micromixer design was employed for efficient mixing, with channel width, height, and length of 0.2, 0.085, and 40 mm respectively. A mathematical model was used to aid the design, and its predictions were compared with experimental results. The deprotonation and epoxidation steps were performed in reaction channels with width and height of 2 and 0.33 mm, while lengths of 450 and 480 mm provided residence times for the two steps of 30 and 16 min, respectively. The effects of operating temperature, reactant and catalyst concentrations, and residence time on reaction performance were investigated. The base case condition (13.47 g/L PLL, 0.132 mol/L H2O2,0.0802 mol/L chalcone, 0.22 mol/L DBU) was found to be optimal, achieving a conversion of 86.7% and enantioselectivity of 87.6%. Comparison between model and experimental results provided insight into the reaction mechanism as well as reactor design. It showed quantitative and, in some cases, qualitative differences. These were attributed to the simplicity of the kinetic model, bubble formation from peroxide decomposition and their stagnation in the rectangular channels, and high viscosity of catalyst solution which may have affected mixing performance.
Reaction in biphasic water/organic solvent system in the presence of surfactant: Inverse phase transfer catalysis versus interfacial catalysis
Boyer, Bernard,Hambardzoumian, Araik,Roque, Jean-Pierre,Beylerian, Norair
, p. 303 - 307 (2000)
Unexpected results obtained during the study of the influence of surfactant concentration on chalcone epoxidation by H2O2 in a water/heptane two-phase system in the presence of a surfactant (DTAB) led us to reconsider the catalytic mechanism of this reaction. Two stirring rates experiments, either low speed (i.e, 100 rpm) or high speed (i.e. 1200 rpm), lead us to discuss kinetic results on the basis of two competitive catalytic processes: an Inverse Phase Transfer Catalysis (IPTC) or an Interfacial Catalysis (IC).
Juliá-Colonna asymmetric epoxidation in a continuously operated chemzyme membrane reactor
Tsogoeva, Svetlana B.,W?ltinger, Jens,Jost, Carsten,Reichert, Dietmar,Kühnle, Adolf,Krimmer, Hans-Peter,Drauz, Karlheinz
, p. 707 - 710 (2002)
Two novel soluble polymer-bound oligo-L-leucines 2 and 5, Which can be retained by a membrane reactor system, have been prepared and used as catalysts for the continuously operated asymmetric epoxidation of chalcone. The optimized batch reaction condition
Highly enantioselective enone epoxidation catalyzed by short solid phase-bound peptides: dominant role of peptide helicity.
Berkessel,Gasch,Glaubitz,Koch
, p. 3839 - 3842 (2001)
The series of L-Leu 1-20-mers, peptides carrying 1-5 N-terminal Gly residues, and oligomers of (S)-beta(3)-Leu and (1R,2R)-2-aminocyclohexanecarboxylic acid were synthesized on TentaGel S NH(2). Five L-Leu residues were found sufficient to catalyze the Ju
Reaction of a polycyclic diketone with lithiated methoxyallene: Synthesis of new functionalized cage compounds
Zimmer, Reinhold,Taszarek, Maurice,Schefzig, Luise,Reissig, Hans-Ulrich
, p. 2046 - 2050 (2008)
Syntheses of several new functionalized cage compounds are described. The key steps of the reaction sequence are addition of lithiated methoxyallene 2 to cage diketone 1, preparation of dehydrated intermediate 5, and its ozonolysis leading to diester 7. Alternatively, 5 could be hydrolyzed to provide cage compound 6 with a bisenone subunit. Via diol 9 chiral crown ether 11 could be prepared in low yield. A first stereoselective epoxidation of chalcone 12 with tert-butyl hydroperoxide in the presence of 11 gave the epoxide 13 in reasonable yield, but with a low level of enantioselectivity.
Theoretical and experimental investigations of the enantioselective epoxidation of olefins catalyzed by manganese complexes
Lin, Jin,Sun, Wei,Tian, Jing,Wang, Fang,Wang, Yong,Zhang, Jisheng
, (2021)
The enantioselective epoxidation of olefin by MnII(R,R-PMCP)(OTf)2, H2O2 and H2SO4 was explored by DFT calculations and experiments. Theoretical results suggest that [MnV(O)(R,R-PMCP)(SO4)]+ species with a triplet ground spin state serves as the active species for the olefin epoxidation. It can be generated by the H2SO4 assisted O-O heterolysis of MnIII(OOH) species. MnIII-persulfate is also involved in this system, but it cannot promote the olefin epoxidation directly, preferring instead to transform into MnV(O). Actually, the asymmetric epoxidation reactions with H2O2/H2SO4 or Oxone provide similar enantioselectivity in the presence of manganese catalyst. These observations further support the transformation of MnIII-persulfate to MnV(O) species.
Catalytic asymmetric epoxidation of chalcones under poly(ethylene glycol)-supported Cinchona ammonium salt catalyzed conditions
Lv, Jian,Wang, Xin,Liu, Juyan,Zhang, Liping,Wang, Yongmei
, p. 330 - 335 (2006)
Dimeric cinchonine, cinchonidine, and quinine have been anchored (via nitrogen) to long linear PEG chains to afford soluble polymer-supported chiral ammonium salts, which were employed as phase-transfer catalysts in the asymmetric epoxidation of chalcones
Mechanistic Insights into the Enantioselective Epoxidation of Olefins by Bioinspired Manganese Complexes: Role of Carboxylic Acid and Nature of Active Oxidant
Du, Junyi,Miao, Chengxia,Xia, Chungu,Lee, Yong-Min,Nam, Wonwoo,Sun, Wei
, p. 4528 - 4538 (2018)
Bioinspired manganese and iron complexes bearing nonporphyrinic tetradentate N4 ligands are highly efficient catalysts in asymmetric oxidation reactions by hydrogen peroxide (H2O2), in which carboxylic acid is employed as an essentia
Inverse phase transfer catalysis versus interfacial catalysis. Effect of medium stirring in the epoxidation reaction of chalcone by hydrogen peroxide
Boyer, Bernard,Hambardzoumian, Araik,Roque, Jean-Pierre,Beylerian, Norair
, p. 1689 - 1691 (2002)
The epoxidation of chalcone by H2O2 has been investigated in a water-heptane two-phase system in the presence of a surfactant (dodecyltrimethylammonium bromide; DTAB) in order to analyse the role played by the rate and the type of stirring (magnetic and sonication). Under these conditions two catalytic processes have been proved to intervene: an inverse phase transfer catalysis (IPTC) or an interfacial catalysis (IC). This latter process appears to be very sensitive to stirring efficiency.
Synthesis of N-containing heterocycles via mechanochemical grinding and conventional techniques
Fahmy, Amin F.M.,El-Sayed, Amira A.,Hemdan, Magdy M.,Hassaballah, Aya I.,Mabied, Ahmed F.
, p. 2679 - 2686 (2017)
Mechano heterocyclic chemistry is a recent quickly growing technique draws the attention of hetrocyclic chemists towards the use of grindstone technique in a solvent free green efficient clean synthesis of many heterocyclic systems. α,β-Epoxy ketones were used as a unique scaffold for synthesis of stable hydroxyazoles. The key advantage of grinding technique over the conventional thermal technique includes its simple, solvent free conditions, as well as facile work up with high yield economy. It is also successful in achieving three of the green chemistry objectives of a solvent free, high atom economy, save energy thus combining the features of both economic and environmental advantages.
Cooxidation of enones during reaction of superoxide with acidic aromatic amines
Takizawa,Nagano,Hirobe
, p. 1894 - 1896 (1991)
Enones can be epoxidized by O2-. in the presence of various compounds having an acidic >NH group. Cyclic voltammetry and ESR study show that O2-. was disproportionated into H2O2 and O2 by these compounds. Furthermore, H2O2 was deprotonated by unreacted O2-. and HOO- was formed, which is widely known to be the effective oxidant in the epoxidation of enones. This confirms the strong basicity of O2-. in aprotic media, and we propose an alternative scheme for the Haber-Weiss reaction in the absence of metal ions.
Enantioselective epoxidation of chalcone catalysed by the artificial enzyme poly-L-leucine: Kinetic mechanism
Carrea, Giacomo,Colonna, Stefano,Meek, Alastair D.,Ottolina, Gianluca,Roberts, Stanley M.
, p. 2945 - 2949 (2004)
An insight into the kinetics, mechanism and optimum reaction conditions of the Julia-Colonna enantioselective epoxidation has been gained using a soluble polyleucine catalyst (PLL), chalcone as the substrate, and hydrogen peroxide (HOO-) as the
Kinetics of chalcone oxidation by peroxide anion catalysed by poly-L-leucine
Carrea, Giacomo,Colonna, Stefano,Meek, Alastair D.,Ottolina, Gianluca,Roberts, Stanley M.
, p. 1412 - 1413 (2004)
An insight into the kinetics, mechanism and optimum reaction conditions of the Julia-Colonna epoxidation has been gained using a soluble polyleucine catalyst.
Zinc-mediated asymmetric epoxidation of α-enones
Enders, Dieter,Zhu, Jiqun,Kramps, Laurenz
, p. 1101 - 1113 (1997)
A new efficient method for the asymmetric epoxidation of α-enones with oxygen in the presence of diethylzinc and a chiral amino alcohol is presented. The epoxidation proceeds in moderate to excellent yields, complete diastereoselectivity and enantiomeric
Synthesis and a Catalytic Study of Diastereomeric Cationic Chiral-at-Cobalt Complexes Based on (R, R)-1,2-Diphenylethylenediamine
Emelyanov, Mikhail A.,Stoletova, Nadezhda V.,Smol'Yakov, Alexander F.,Il'In, Mikhail M.,Maleev, Victor I.,Larionov, Vladimir A.
supporting information, p. 13960 - 13967 (2021/09/11)
Here we report the first synthesis of two diastereomeric cationic octahedral Co(III) complexes based on commercially available (R,R)-1,2-diphenylethylenediamine and salicylaldehyde. Both diastereoisomers with opposite chiralities at the metal center (Λ and Δconfigurations) were prepared. The new Co(III) complexes possessed both acidic hydrogen-bond donating (HBD) NH moieties and nucleophilic counteranions and operate as bifunctional chiral catalysts for the challenging kinetic resolution of terminal and disubstituted epoxides by the reaction with CO2 under mild conditions. The highest selectivity factor (s) of 2.8 for the trans-chalcone epoxide was achieved at low catalyst loading (2 mol %) in chlorobenzene, which is the best achieved result currently for this type of substrate.
Asymmetric Epoxidation of Olefins Catalyzed by Substituted Aminobenzimidazole Manganese Complexes Derived from L-Proline
Lin, Jin,Sun, Wei,Tian, Jing,Xia, Chungu,Zhang, Jisheng
supporting information, (2021/11/16)
A family of manganese complexes [Mn(Rpeb)(OTf)2] (peb=1-(1-ethyl-1H-benzo[d]imidazol-2-yl)-N-((1-((1-ethyl-1H-benzo[d]imidazol-2-yl)methyl) pyrrolidin-2-yl)methyl)-N-methylmethanamine)) derived from L-proline has been synthesized and characterized, where R refers to the group at the diamine backbone. X-ray crystallographic analyses indicate that all the manganese complexes [Mn(Rpeb)(OTf)2] exhibit cis-α topology. These types of complexes are shown to catalyze the asymmetric epoxidation of olefins employing H2O2 as a terminal oxidant with up to 96% ee. Obviously, the R group of the diamine backbone can influence the catalytic activity and enantioselectivity in the asymmetric epoxidation of olefins. In particular, Mn(i-Prpeb)(OTf)2 bearing an isopropyl arm, cannot catalyze the epoxidation reaction with H2O2 as the oxidant. However, when PhI(OAc)2 is used as the oxidant instead, all the manganese complexes including Mn(i-Prpeb)(OTf)2 can promote the epoxidation reactions efficiently. Taken together, these results indicate that isopropyl substitution on the Rpeb ligand inhibits the formation of active Mn(V)-oxo species in the H2O2/carboxylic acid system via an acid-assisted pathway.
Asymmetric Epoxidation of Enones Promoted by Dinuclear Magnesium Catalyst
Jaszczewska-Adamczak, Joanna A.,Mlynarski, Jacek
supporting information, p. 4247 - 4255 (2021/07/17)
Asymmetric synthesis with cheaper and non-toxic alkaline earth metal catalysts is becoming an important and sustainable alternative to conventional catalytic methodologies mostly relying on precious metals. In spite of some sustainable methods for enantioselective epoxidation of enones, the development of a well-defined and efficient catalyst based on magnesium complexes for these reactions is still a challenging task. In this perspective, we present the application of chiral dinuclear magnesium complexes for asymmetric epoxidation of a broad range of electron-deficient enones. We demonstrate that the in situ generated magnesium-ProPhenol complex affords enantioenriched oxiranes in high yields and with excellent enantioselectivities (up to 99% ee). Our extensive study verifies the literature data in this area and provides a step forward to better understand the factors controlling the oxygenation process. Elaborated catalyst offers mild reaction conditions and a truly wide substrate scope. (Figure presented.).
