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.
Chiral amplification by polypeptides and its relevance to prebiotic catalysis
Kelly, David H.,Meek, Alastair,Roberts, Stanley M.
, p. 2021 - 2022 (2004)
Polyleucine prepared from scalemic Leu-NCA monomers, shows high chiral amplification in the Julia-Colonna epoxidation of chalcone.
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).
The effect of the primary structure of the polypeptide catalyst on the enantioselectivity of the Julia-Colonna asymmetric epoxidation of enones
Bentley,Flood,Roberts,Skidmore,Smith,Smith
, p. 1616 - 1617 (2001)
Epoxidation of chalcone (1), using basic hydrogen peroxide, catalysed by polypeptides with defined primary structures demonstrates that the residues in the chain near to the N-terminus determine the stereochemical outcome of the reaction.
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
Design of a stabilized short helical peptide and its application to catalytic enantioselective epoxidation of (E)-chalcone
Yamagata, Nanako,Demizu, Yosuke,Sato, Yukiko,Doi, Mitsunobu,Tanaka, Masakazu,Nagasawa, Kazuo,Okuda, Haruhiro,Kurihara, Masaaki
, p. 798 - 801 (2011)
Stabilized short helical heptapeptides containing a combination of an α-aminoisobutyric acid as a helical promoter and l/d-serine derivatives to produce cross-linked units were synthesized. The cyclic peptide R 3,7R-2, which had d-se
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
Asymmetric C-C Bond Forming Reactions by Chiral Crown Catalysts; Darzens Condensation and Nitroalkane Addition to the Double Bond
Bakó, Péter,Sz?ll?sy, áron,Bombicz, Petra,T?ke, László
, p. 291 - 292 (1997)
A new, efficient crown ether 1 anellated to a sugar derivative has been prepared which shows significant asymmetric induction as phase transfer catalyst in the Michael addition of 2-nitropropane to chalcone (60% ee for the S antipode) and in the Darzens c
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.
Synthesis of d-mannitol-based crown ethers and their application as catalyst in asymmetric phase transfer reactions
Nemcsok, Tamás,Rapi, Zsolt,Keglevich, Gy?rgy,Grün, Alajos,Bakó, Péter
, p. 407 - 419 (2018)
A few new d-mannitol-based monoaza-15-crown-5 type chiral lariat ethers and 18-crown-6 type macrocycles were synthesized. These crown compounds were used as phase transfer catalysts in asymmetric Michael addititons and in a Darzens condensation under mild conditions to afford the corresponding products in a few cases in good to excellent enantioselectivities. In the Michael addition of diethyl acetoxymalonate to trans-chalcone, in the addition of diethyl acetamidomalonate to ?-nitrostyrene, in the reaction of diethyl bromomalonate with benzylidene malononitriles, in the cyclopropanation reaction of diethyl bromomalonate and 2-benzylidene-1,3-indandione, and in the Darzens condensation of α-chloroacetophenone with benzaldehyde, maximum enantioselectivities of 39%, 65%, 99%, 56%, and 62%, respectively, were obtained in the presence of the d-mannitol-based macrocycles as the catalysts.
