Kinetic Resolution Of Epoxides Research Articles

Asymmetric Ring-Opening of Epoxides Catalyzed by Metal–Salen Complexes

The asymmetric ring-opening of epoxides is an important reaction in organic synthesis, since it allows for the enantioselective installation of two vicinal functional groups with specific stereochemistry within one step from a highly available starting material. An effective class of catalysts for the asymmetric ring-opening of epoxides is metal–salen complexes. This review summarizes the development of metal–salen catalyzed enantioselective desymmetrization of meso-epoxides and kinetic resolution of epoxides with various nucleophiles, including the design and application of both homogeneous- and heterogeneous epoxide-opening catalysts as well as multi-metallic covalent and supramolecular catalytic systems.

Kinetic Resolution of Epoxides with CO2 Catalyzed by a Chiral-at-Iridium Complex.

Chiral-at-metal bis-cyclometalated iridium(III) complexes are introduced as a new class of chiral catalysts for the reaction of epoxides with CO2 to form cyclic carbonates under conditions of kinetic resolution. Reactions are typically performed at room temperature in the presence of 1 mol % of iridium catalyst and 1.5 mol % of tetraethylammonium bromide as the nucleophilic cocatalyst to provide selectivity factors of up to 16.6. A variety of monosubstituted epoxides, including styrene epoxide, epoxides with aliphatic side chains, glycidyl ethers, and a glycidyl ester, are found to be suitable substrates. No polymerization side reaction is observed for any of the investigated substrates.

ChemInform Abstract: Asymmetric Syntheses of 3,4‐Disubstituted Tetrahydroquinoline Derivatives Using (+)‐Sparteine‐Mediated Electrophilic Substitution.

AbstractA novel methodology for the asymmetric synthesis of trans‐3,4‐diaryl‐substituted tetrahydroquinolines via sparteine‐assisted stereoselective lithiation of o‐substituted N‐pivaloylanilines (I), kinetic resolution of epoxides in substitution and a stereospecific Mitsunobu cyclization is developed.

Asymmetric Syntheses of 3,4‐Disubstituted Tetrahydroquinoline Derivatives Using (+)‐Sparteine‐mediated Electrophilic Substitution

A novel methodology for the asymmetric synthesis of trans-3,4-diaryl-substituted tetrahydroquinolines via sparteine-assisted stereoselective lithiation of o-substituted N-pivaloylanilines (I), kinetic resolution of epoxides in substitution and a stereospecific Mitsunobu cyclization is developed.

Hydrolytic Kinetic Resolution of Epoxides Using Polymer-Supported Cobalt Catalyst

Hydrolytic Kinetic Resolution of Epoxides Using Polymer-Supported Cobalt Catalyst

Kinetic Resolution of Epoxides by a C—C Bond‐Forming Reaction: Highly Enantioselective Addition of Indoles to cis, trans, and meso Aromatic Epoxides Catalyzed by [Cr(salen)] Complexes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Kinetic resolution of epoxides by a C-C bond-forming reaction: highly enantioselective addition of indoles to cis, trans, and meso aromatic epoxides catalyzed by [Cr(salen)] complexes.

Kinetic resolution of epoxides by a C-C bond-forming reaction: highly enantioselective addition of indoles to cis, trans, and meso aromatic epoxides catalyzed by [Cr(salen)] complexes.

Kinetic Resolution of Epoxides by a CC Bond‐Forming Reaction: Highly Enantioselective Addition of Indoles to cis, trans, and meso Aromatic Epoxides Catalyzed by [Cr(salen)] Complexes

Die hohe Reaktivität von Indolen führte zu einer neuartigen kinetischen Racematspaltung bei Epoxiden. [Cr(salen)] katalysiert effizient eine C-C-Bindungsbildung, die die Trennung von aromatischen cis- und trans-Epoxiden ermöglicht (siehe Schema). Mit dem gleichen Katalysatorsystem ließen sich durch asymmetrische Ringöffnung von meso-Stilbenoxid Indolylderivate in hohen Enantiomerenüberschüssen (bis 98 %) erhalten. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2001/2004/z52073_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Construction and Characterisation of a Genetically Engineered Escherichia coli Strain for the Epoxide Hydrolase-catalysed Kinetic Resolution of Epoxides

The Rhodotorula glutinis epoxide hydrolase, Eph1, was produced in the heterologous host Escherichia coli BL21(DE3) in order to develop a highly effective epoxide hydrolysis system. A 138-fold increase in Eph1 activity was found in cell extracts of the recombinant E. coli when compared to cell extracts of Rhodotorula glutinis, despite the formation of Eph1 inclusion bodies. Optimization of cultivation conditions and co-expression of molecular chaperones resulted in a further increase in activity and a reduction of the inclusion bodies formation, respectively. Compared to Rhodotorula glutinis cells and cell extracts, a total increase in Eph1 activity of over 200 times was found for both Escherichia coli cells and crude enzyme preparations of these cells. The improved conditions for recombinant Eph1 production were used to demonstrate the Eph1-catalysed kinetic resolution of a new Eph1 substrate, 1-oxaspiro[2.5]octane-2-carbonitrile.

Enantioselective parallel synthesis using polymer-supported chiral Co(salen) complexes.

[formula: see text] The kinetic resolution of epoxides with phenols catalyzed by a polymer-supported Co(salen) complex is applied to the first enantioselective catalytic synthesis of parallel libraries. The corresponding 1-aryloxy-2-alcohols are obtained in high yield, purity, and enantiomeric excess. Further elaboration with diversity elements provides highly efficient access to important classes of pharmacologically active compounds.

Kinetic resolution of epoxides by chiral organoaluminum catalyst short synthesis of (-)-C 16 juvenile hormone

The use of chiral organoaluminum reagent as a catalyst to resolve simple ketoepoxides is explored. The optically pure ketoepoxide 10 was recovered after 80% conversion. The recovered pure epoxide is a useful chiral building block in the synthesis of chiral terpenes. The method applies for the short asymmetric synthesis of the juvenile hormone by the synthetic route which depends on the palladium-catalyzed coupling process.