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Asymmetric Mannich Reactions (asymmetric + mannich_reaction)
Selected AbstractsCatalytic Asymmetric Mannich Reaction of Glycine Derivatives with N -Tosylimines using Copper(I)/TF-BiphamPhos ComplexADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Gang Liang Abstract The direct asymmetric Mannich reaction of glycine Schiff bases with N -tosylimines has been developed with the tetrakis(acetonitrile)copper(I) tetrafluoroborate [Cu(CH3CN)4BF4]/TF-BiphamPhos complex. This catalytic system performs well over a broad range of substrates, furnishing anti -adducts of various ,,,-diamino acid esters in good yields with up to 94:6 diastereoselectivity and 97% enantioselectivity. [source] Axially Chiral Phosphine-Oxazoline Ligands in Silver(I)- Catalyzed Asymmetric Mannich Reaction of Aldimines with TrimethylsiloxyfuranADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009Hong-Ping Deng Abstract A new asymmetric catalytic system for the Mannich reaction of aldimines with trimethylsiloxyfuran is described. The combination of an axially chiral phosphine-oxazoline ligand (S)-2-[(R)-2,-(diphenylphosphino)-1,1,-binaphthyl-2-yl]-4-phenyl-4,5-dihydrooxazole with silver acetate and 2,2,2-trifluoroacetic acid is a very effective catalytic system in the asymmetric Mannich reaction of various aldimines with trimethylsiloxyfuran in dichloromethane at ,78,°C, affording the corresponding adducts in up to 99% yield, 99:1 (dr) and 99% ee (major diastereoisomer) under mild conditions. [source] Asymmetric Mannich Reaction of Fluorinated Ketoesters with a Tryptophan-Derived Bifunctional Thiourea Catalyst,ANGEWANDTE CHEMIE, Issue 41 2009Xiao Han Fluorierte quartäre Stereozentren: Der neuartige difunktionelle Katalysator 1, der von natürlichem Tryptophan abgeleitet ist, vermittelt die hoch enantioselektive Mannich-Reaktion von ,-Fluor-,-ketoestern zu fluorierten chiralen Molekülen mit vicinalen quartären und tertiären stereogenen Zentren. Ein ungewöhnliches ,-Fluor-,-lactam wurde ebenfalls mit dieser Methode synthetisiert (siehe Schema; Boc=tert -Butoxycarbonyl). [source] ChemInform Abstract: Asymmetric Mannich Reaction of Dicarbonyl Compounds with ,-Amido Sulfones Catalyzed by Cinchona Alkaloids and Synthesis of Chiral Dihydropyrimidones.CHEMINFORM, Issue 18 2008Sha Lou 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Catalytic Asymmetric Mannich Reactions of Sulfonylacetates,ANGEWANDTE CHEMIE, Issue 31 2009Carlo Cassani Sulfon gegen Sulfon: Arylsulfonylacetate sind Syntheseäquivalente für eine Vielzahl an ,-Carboxylatanionen. Durch Phasentransferkatalyse (PTC) gelangen ihre milde Deprotonierung und die katalytische asymmetrische Addition an hochreaktive, in,situ aus ,-Amidosulfonen erzeugte Imine (siehe Schema; Pg=Schutzgruppe). Die Nützlichkeit der Produkte in der Synthese wurde mit ihrer einfachen Überführung in eine Reihe von ,-Aminosäurederivate gezeigt. [source] ChemInform Abstract: Organocatalytic Asymmetric Mannich Reactions with N-Boc- and N-Cbz-Protected ,-Amido Sulfones (Boc: tert-Butoxycarbonyl, Cbz: Benzyloxycarbonyl).CHEMINFORM, Issue 5 2008Olindo Marianacci 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Asymmetric Mannich Reactions with in situ Generation of Carbamate-Promoted Imines by an Organic Catalyst.CHEMINFORM, Issue 26 2007Jun Song 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] Expedient Synthesis of Chiral 1,2- and 1,4-Diamines: Protecting Group Dependent Regioselectivity in Direct Organocatalytic Asymmetric Mannich Reactions.CHEMINFORM, Issue 42 2006Naidu S. Chowdari 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] ChemInform Abstract: Asymmetric Mannich Reactions with ,-Silylated Trimethylsilyl Enol Ethers and N-Alkoxycarbonyl Imines.CHEMINFORM, Issue 29 2002Dieter Enders Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Organocatalytic Asymmetric Mannich Reactions with N -Boc and N -Cbz Protected ,-Amido Sulfones (Boc: tert -Butoxycarbonyl, Cbz: Benzyloxycarbonyl)CHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2007Olindo Marianacci Abstract Different malonates and ,-ketoesters can react with N - tert -butoxycarbonyl- (N -Boc) and N -benzyloxycarbonyl- (N -Cbz) protected ,-amido sulfones in an organocatalytic asymmetric Mannich-type reaction. The reaction makes use of a simple and easily obtained phase-transfer catalyst and proceeds under very mild and user-friendly conditions. The optimised protocol avoids the preparation and the isolation of the relatively unstable N -Boc and N- Cbz imines that are generated in situ from the bench-stable ,-amido sulfones. The corresponding Mannich bases are generally obtained in good yields and enantioselectivities, and can be readily transformed into key compounds, such as optically active ,3 -amino acids in one easy step. Enantioenriched N -Boc and N -Cbz protected ,-amino acids that are suitable for peptide synthesis are also available from the Mannich adducts through simple manipulations. Control experiments showed the dual role of the enolate,catalyst ion pair in this reaction, as well as the crucial role of the presence of water to achieve high enantioselectivities. [source] Organocatalytic Direct Asymmetric Mannich Reactions of Hydroxyacetone by (2S,5S)-Pyrrolidine-2,5-dicarboxylic AcidCHINESE JOURNAL OF CHEMISTRY, Issue 10 2008Qing GU Abstract The direct one-pot three-component asymmetric Mannich reactions of hydroxyacetone with anilines and benzaldehydes in the presence of (2S,5S)-pyrrolidine-2,5-dicarboxylic acid afforded syn -1,2-amino alcohols in good-to-excellent yields (64% ,95%) and up to 96% ee. [source] Axially Chiral Phosphine-Oxazoline Ligands in Silver(I)- Catalyzed Asymmetric Mannich Reaction of Aldimines with TrimethylsiloxyfuranADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009Hong-Ping Deng Abstract A new asymmetric catalytic system for the Mannich reaction of aldimines with trimethylsiloxyfuran is described. The combination of an axially chiral phosphine-oxazoline ligand (S)-2-[(R)-2,-(diphenylphosphino)-1,1,-binaphthyl-2-yl]-4-phenyl-4,5-dihydrooxazole with silver acetate and 2,2,2-trifluoroacetic acid is a very effective catalytic system in the asymmetric Mannich reaction of various aldimines with trimethylsiloxyfuran in dichloromethane at ,78,°C, affording the corresponding adducts in up to 99% yield, 99:1 (dr) and 99% ee (major diastereoisomer) under mild conditions. [source] | ||||||||||||||||||||||