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Cyclopropane Derivatives (cyclopropane + derivative)
Selected AbstractsKinetic Enzymatic Resolution of Cyclopropane DerivativesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 12 2003Jörg Pietruszka Abstract The kinetic enzymatic resolution of various cyclopropane derivatives was systematically investigated. The study focused on synthetically useful cyclopropylmethanols (e.g., 18a/j or 19a/j) as well as some rarely investigated cyclopropanols (e.g., 24/25 or 27). The combination of enantioselective catalytic or diastereoselective synthesis of enantiomerically enriched compounds with enzymatic approaches ultimately led to the most convenient route to enantiomerically pure starting materials. Again, this was especially proven for the synthesis of cyclopropanols 18a/j and 19a/j. Key to the successful investigation was to rigorously establish an analytical tool for the analysis of enantiomeric composition of reaction mixtures. [source] Epoxysilane Rearrangement Induced by a Carbanion Generated by Conjugate Addition of Enolates of Chloroacetate and ,-Chloroacetamides: Formation of Functionalized Cyclopropane Derivatives.CHEMINFORM, Issue 35 2006Noriko Okamoto Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Kinetic Enzymatic Resolution of Cyclopropane Derivatives.CHEMINFORM, Issue 20 2004Joerg Pietruszka Abstract For Abstract see ChemInform Abstract in Full Text. [source] Zirconium-Mediated Conversion of Homoallylic Ethers into Cyclopropane Derivatives.CHEMINFORM, Issue 39 2003Vincent Gandon Abstract For Abstract see ChemInform Abstract in Full Text. [source] Rhodium(II)-Catalyzed Inter- and Intramolecular Cyclopropanations with Diazo Compounds and Phenyliodonium Ylides: Synthesis and Chiral AnalysisHELVETICA CHIMICA ACTA, Issue 2 2005Ashraf Ghanem Different classes of cyclopropanes derived from Meldrum's acid (=2,2-dimethyl-1,3-dioxane-4,6-dione; 4), dimethyl malonate (5), 2-diazo-3-(silyloxy)but-3-enoate 16, 2-diazo-3,3,3-trifluoropropanoate 18, diazo(triethylsilyl)acetate 24a, and diazo(dimethylphenylsilyl)acetate 24b were prepared via dirhodium(II)-catalyzed intermolecular cyclopropanation of a set of olefins 3 (Schemes,1 and 4,6). The reactions proceeded with either diazo-free phenyliodonium ylides or diazo compounds affording the desired cyclopropane derivatives in either racemic or enantiomer-enriched forms. The intramolecular cyclopropanation of allyl diazo(triethylsilyl)acetates 28, 30, and 33 were carried out in the presence of the chiral dirhodium(II) catalyst [Rh2{(S)-nttl)4}] (9) in toluene to afford the corresponding cyclopropane derivatives 29, 31 and 34 with up to 37% ee (Scheme,7). An efficient enantioselective chiral separation method based on enantioselective GC and HPLC was developed. The method provides information about the chemical yields of the cyclopropane derivatives, enantioselectivity, substrate specifity, and catalytic activity of the chiral catalysts used in the inter- and intramolecular cyclopropanation reactions and avoids time-consuming workup procedures. [source] Polymer-Supported Hantzsch 1,4-Dihydropyridine Ester: An Efficient Biomimetic Hydrogen Source for the Reduction of Ketimines and Electron-Withdrawing Group Conjugated OlefinsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2010Jun Che Abstract A polymer-supported Hantzsch 1,4-dihydropyridine ester was observed to be a useful selective reducing agent for the reduction of ketimines and electron-withdrawing conjugated olefins. The rate of the reduction of electron-withdrawing conjugated olefins is dependent on the nature of the conjugated substituents and could be enhanced by microwave irradiation. The reduction of (Z)-,-cyano-,-bromomethylcinnamates to cyclopropane derivatives using polymer-supported Hantzsch 1,4-dihydropyridine ester was found to proceed stereoselectively and in good yields. [source] Kinetic Enzymatic Resolution of Cyclopropane DerivativesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 12 2003Jörg Pietruszka Abstract The kinetic enzymatic resolution of various cyclopropane derivatives was systematically investigated. The study focused on synthetically useful cyclopropylmethanols (e.g., 18a/j or 19a/j) as well as some rarely investigated cyclopropanols (e.g., 24/25 or 27). The combination of enantioselective catalytic or diastereoselective synthesis of enantiomerically enriched compounds with enzymatic approaches ultimately led to the most convenient route to enantiomerically pure starting materials. Again, this was especially proven for the synthesis of cyclopropanols 18a/j and 19a/j. Key to the successful investigation was to rigorously establish an analytical tool for the analysis of enantiomeric composition of reaction mixtures. [source] | ||||||||||