853997-11-2Relevant academic research and scientific papers
Isotope Effects Reveal an Alternative Mechanism for "iminium-Ion" Catalysis
Izzo, Joseph A.,Poulsen, Pernille H.,Intrator, Jeremy A.,J?rgensen, Karl Anker,Vetticatt, Mathew J.
, p. 8396 - 8400 (2018)
A novel mechanism for the epoxidation of enals with hydrogen peroxide catalyzed by diarylprolinol silyl ether supported by experimental 13C kinetic isotope effects (KIEs) and density functional theory calculations is presented. Normal 13/
Enantiocomplementary Epoxidation Reactions Catalyzed by an Engineered Cofactor-Independent Non-natural Peroxygenase
Crotti, Michele,Kataja, Kim M.,Poelarends, Gerrit J.,Saravanan, Thangavelu,Xu, Guangcai
supporting information, p. 10374 - 10378 (2020/04/23)
Peroxygenases are heme-dependent enzymes that use peroxide-borne oxygen to catalyze a wide range of oxyfunctionalization reactions. Herein, we report the engineering of an unusual cofactor-independent peroxygenase based on a promiscuous tautomerase that accepts different hydroperoxides (t-BuOOH and H2O2) to accomplish enantiocomplementary epoxidations of various α,β-unsaturated aldehydes (citral and substituted cinnamaldehydes), providing access to both enantiomers of the corresponding α,β-epoxy-aldehydes. High conversions (up to 98 %), high enantioselectivity (up to 98 % ee), and good product yields (50–80 %) were achieved. The reactions likely proceed via a reactive enzyme-bound iminium ion intermediate, allowing tweaking of the enzyme's activity and selectivity by protein engineering. Our results underscore the potential of catalytic promiscuity for the engineering of new cofactor-independent oxidative enzymes.
Nanosheet-enhanced efficiency in amine-catalyzed asymmetric epoxidation of Α, Β-unsaturated aldehydes via host-guest synergy
Liu, Hui,An, Zhe,He, Jing
, p. 69 - 77 (2017/11/15)
Amine-catalyzed asymmetric epoxidation of α, β-unsaturated aldehydes has been promoted by attaching the nanosheets of layered double hydroxides (LDHs), a natural and/or synthetic anionic layered compound. 76% of epoxide yield and 93% ee of major diastereomer have been afforded in the asymmetric epoxidation of cinnamaldehyde. The amine sites employed here are the amino group in α-amino acid anion intercalated in the interlayer space of LDHs. The nanosheets of LDHs have been revealed to play key role in the enhancement of catalytic activity by affording the desired basicity and the boost of enantioselectivity by serving as the rigid substituent of amino acids. The hydrophobic interlayer microenvironment and ordered arrangement of intercalated amino acid anions additionally contribute to the catalytic efficacy. Stronger interlayer hydrophobicity favors the conversion and epoxide yield and better arrangement of interlayer anions favors the ee.
Highly efficient asymmetric synthesis of α,β-epoxy esters via one-pot organocatalytic epoxidation and oxidative esterification
Xuan, Yi-Ning,Lin, Han-Sen,Yan, Ming
supporting information, p. 1815 - 1817 (2013/04/10)
Highly enantioselective synthesis of α,β-epoxy esters was achieved via one-pot organocatalytic epoxidation and consequent oxidative esterification. Excellent enantioselectivities (up to 99% ee) and good yields were obtained for a variety of α,β-epoxy esters. The method was readily scaled. Furthermore the product was applied towards the synthesis of (-)-clausenamide with excellent enantioselectivities (>99% ee).
Asymmetric epoxidation of α,β-unsaturated aldehydes in aqueous media catalyzed by resin-supported peptide-containing unnatural amino acids
Akagawa, Kengo,Kudo, Kazuaki
experimental part, p. 843 - 847 (2011/06/11)
The enantio- and diastereoselective epoxidation of α,β- unsaturated aldehydes in aqueous media was realized using a resin-supported peptide catalyst. Introducing the hydrophobic and bulky unnatural amino acid 3-(1-pyrenyl)alanine into the peptide sequence was effective for enhancing the reaction rate and enantioselectivity.
ORGANIC SALTS AND METHOD FOR PRODUCING CHIRAL ORGANIC COMPOUNDS
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Page/Page column 9, (2009/02/11)
The invention relates to a method for producing chiral organic compounds by asymmetric catalysis, using ionic catalysts comprising a chiral catalyst anion. The claimed method is suitable for reactions which are carried out over cationic intermediate stages, such as iminium ions or acyl pyridinium ions. The invention enables the production of chiral compounds with high ee values, that until now could only be obtained by means of costly purification methods.
Asymmetric counteranion-directed catalysis for the epoxidation of enals
Wang, Xingwang,List, Benjamin
, p. 1119 - 1122 (2008/09/21)
(Chemical Equation Presented) A new mode of chiral anion catalysis: A powerful chiral-counteranion strategy for catalytic asymmetric epoxidations using the newly discovered catalyst 1 has been applied to the epoxidation of α,β-unsaturated aldehydes together with tert-butyl hydroperoxide as the oxidant (see scheme). Remarkably, this system provides the corresponding epoxides in high diastereo- and enantioselectivity for both di- and trisubstituted enals.
Amine-catalyzed asymmetric epoxidation of α,β-unsaturated aldehydes
Zhao, Gui-Ling,Ibrahem, Ismail,Sunden, Henrik,Cordova, Armando
, p. 1210 - 1224 (2008/09/17)
The direct organocatalytic enantioselective epoxidation of α,β-unsaturated aldehydes with different peroxides is presented. Proline, chiral pyrrolidine derivatives, and amino acid-derived imidazolidinones catalyze the asymmetric epoxidation of α,β-unsatur
Organocatalytic asymmetric synthesis of 1,2,3-prim,sec,sec-triols
Zhao, Gui-Ling,Dziedzic, Pawel,Ibrahem, Ismail,Córdova, Armando
, p. 3521 - 3524 (2007/10/03)
A tandem organocatalytic asymmetric synthesis of 1,2,3-triols using a,b-unsaturated aldehydes as the substrates and hydrogen peroxide as the oxidant is presented. The reaction can also be applied to the asymmetric synthesis of 3-chloro-1,2-propandiols. Georg Thieme Verlag Stuttgart.
Asymmetric organocatalytic epoxidation of α,β-unsaturated aldehydes with hydrogen peroxide
Marigo, Mauro,Franzen, Johan,Poulsen, Thomas B.,Zhuang, Wei,Jorgensen, Karl Anker
, p. 6964 - 6965 (2007/10/03)
The first asymmetric organocatalytic epoxidation of α,β-unsaturated aldehydes is presented. A chiral bisaryl-silyl-protected pyrrolidine acts as a very selective epoxidation organocatalyst using simple oxidation agents, such as hydrogen peroxide and tert-butyl hydroperoxide. The asymmetric epoxidation reactions proceed under environmental friendly reaction condition in, for example, water mixtures of alcohols, and the scope of the reaction is demonstrated by the formation of optically active α,β-epoxy aldehydes in high yields and enantioselectivities >94% ee. Furthermore, the direct synthesis of the sex pheromone from an acaric mite by asymmetric epoxidation of citral is presented. Copyright
