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 of methyl 4,6-di-o-ethyl-α-d-glucopyranoside-based azacrown ethers and their effects in asymmetric reactions
Bagi, Péter,Bakó, Péter,Heged?s, László,Orbán, István,Rapi, Zsolt,Varga, Bertalan
, (2021/08/12)
Carbohydrate-based crown ethers have been reported to be able to generate asymmetric induction in certain reactions. Previously, it was proved that the monosaccharide unit, the anomeric substituent, and the sidearm could influence the catalytic activity of the monoaza-15-crown-5 macrocycles derived from sugars. In order to gain information about the effect of the flexibility, 4,6-di-O-ethyl-glucoside-based crown compounds were synthesized, and their efficiency was compared to the 4,6-O-benzylidene analogues. It was found that the absence of the two-ring annulation has a negative effect on the enantioselectivity in liquid-liquid two-phase reactions: in the Darzens condensation of 2-chloroacetophenone and in the epoxidation of chalcone. The same trend was observed in the solid-liquid phase Michael addition of diethyl acetamidomalonate. Surprisingly, in the solid-liquid phase cyclopropanation of benzylidenemalononitrile, one of the new catalysts was highly enantioselective (99% ee).
Asymmetric epoxidation of α,β-unsaturated ketones via an amine-thiourea dual activation catalysis
Zhang, Lu-Wen,Wang, Li,Ji, Nan,Dai, Si-Yang,He, Wei
supporting information, (2021/03/15)
A simple asymmetric epoxidation method is developed to effectively synthesize chiral α-carbonyl epoxides through an amine-thiourea dual activation catalysis. In this method, TBHP, as an oxidant, determined the reaction rate, and the chiral amine-thiourea catalyst effectively controlled the stereoselectivity of the reaction, and KOH promoted deprotonation. 22 examples of α,β-unsaturated ketones with various substituent groups are smoothly converted into α-carbonyl epoxides with moderate to excellent enantiomeric excess.
