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Reaction Cascade (reaction + cascade)
Selected AbstractsChemInform Abstract: Palladium-Catalyzed Carboxamidation Reaction and Aldol Condensation Reaction Cascade: A Facile Approach to Ring-Fused Isoquinolinones.CHEMINFORM, Issue 12 2009Gagan Chouhan 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] Biocatalytic Asymmetric Rearrangement of a Methylene-Interrupted Bis-epoxide: Simultaneous Control of Four Asymmetric Centers Through a Biomimetic Reaction CascadeCHEMISTRY - A EUROPEAN JOURNAL, Issue 14 2004Silvia M. Glueck Abstract Asymmetric enzyme-catalyzed hydrolysis of methylene-interrupted bis-epoxides 1,a and 1,b catalyzed by bacterial epoxide hydrolases furnished tetrahydrofuran derivatives 2,a and 2,b through a hydrolysis,rearrangement cascade. Whereas racemic bis-oxiranes 1,b,d underwent kinetic resolution with moderate stereoselectivities to yield products with up to 92,% ee and 66,% de: meso -bis-oxirane cis,cis- 1,a was transformed into (6R,7R,9S,10S)- 2,a in 94,% ee and 89,% de at high conversion (85,%) by Rhodococcus sp. CBS 717.73 as the major product. The reaction sequence resembles a biomimetic reaction cascade and provides an efficient entry into the structural core of annonaceous acetogenins with simultaneous control of four stereocenters. [source] ChemInform Abstract: A One-Pot, Microwave-Influenced Synthesis of Diverse Small Molecules by Multicomponent Reaction Cascades.CHEMINFORM, Issue 16 2008Soumava Santra 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] 2H -Pyrrole Derivatives from an Aza-Nazarov Reaction Cascade Involving Indole as the Neutral Leaving GroupEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2008Nugzar Ghavtadze Abstract Trifluoromethyl-substituted N -indolinyl-1-aza-1,4-dien-3-ones 4, which are accessible in good yields from indolinylimino esters 6 in a two-step procedure, undergo a novel type of aza-Nazarov cyclization if treated with strong acids to give the hitherto unknown 3-hydroxy-5H -pyrrole derivatives 8a,p. The solvent-free polyphosphoric acid/acyl anhydride system as the acidic reaction medium is especially efficient and requires only short reaction times. According to quantum chemical calculations the key step in the reaction cascade is the cleavage of the N,N bond of the hydrazone fragment of a protonated N -(indolin-1-yl)-1-aza-1,4-dien-3-one intermediate such as 10. This intermediate releases 3H -indole as an unusual, but very efficient neutral leaving group. Several 1-aza-1,4-dien-3-ones 4 and some 3-hydroxy-5H -pyrrole derivatives 8 were characterized by X-ray diffraction.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Deracemisation of Mandelic Acid to Optically Pure Non-Natural L -Phenylglycine via a Redox-Neutral Biocatalytic CascadeADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2010Verena Resch Abstract A biocatalytic redox-neutral reaction cascade was designed for the deracemisation of racemic mandelic acid to yield optically pure L -phenylglycine employing three enzymes. The cascade consisted of three steps: a racemisation, an enantioselective oxidation and a stereoselective reductive amination. The enantioselective oxidation of D -mandelic acid to the corresponding oxo acid was coupled with the stereoselective reductive amination of the latter; thus the oxidation as well as the reduction reactions were performed simultaneously. The formal hydrogen abstracted in the first step , the oxidation , was consumed in the reductive amination allowing a redox-neutral cascade due to a cascade-internal cofactor recycling. The enantiomers of the starting material were interconverted by a racemase (mandelate racemase) ensuring that in theory 100% of the starting material can be transformed. Using this set-up racemic mandelic acid was transformed to optically pure L -phenylglycine (ee >97%) at 94% conversion without the requirement of any additional redox reagents in stoichiometric amounts. [source] Serum Albumin-Catalyzed Trigger System by Using a Tandem Kemp Elimination/,-Elimination ReactionCHEMBIOCHEM, Issue 5 2005Guillaume Boucher Dr. Prodrug activation: Serum albumins (BSA or HSA) are shown to catalyze a reaction cascade that involves the ring-opening of an isoxazole ring followed by a ,-elimination reaction, as per the scheme. The 4-(aryloxymethyl)isoxazole derivative of estrone is selectively removed in vitro by albumins, thus demonstrating the potential of this new protective group. [source] Biocatalytic Asymmetric Rearrangement of a Methylene-Interrupted Bis-epoxide: Simultaneous Control of Four Asymmetric Centers Through a Biomimetic Reaction CascadeCHEMISTRY - A EUROPEAN JOURNAL, Issue 14 2004Silvia M. Glueck Abstract Asymmetric enzyme-catalyzed hydrolysis of methylene-interrupted bis-epoxides 1,a and 1,b catalyzed by bacterial epoxide hydrolases furnished tetrahydrofuran derivatives 2,a and 2,b through a hydrolysis,rearrangement cascade. Whereas racemic bis-oxiranes 1,b,d underwent kinetic resolution with moderate stereoselectivities to yield products with up to 92,% ee and 66,% de: meso -bis-oxirane cis,cis- 1,a was transformed into (6R,7R,9S,10S)- 2,a in 94,% ee and 89,% de at high conversion (85,%) by Rhodococcus sp. CBS 717.73 as the major product. The reaction sequence resembles a biomimetic reaction cascade and provides an efficient entry into the structural core of annonaceous acetogenins with simultaneous control of four stereocenters. 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