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Unsaturated Aldehydes (unsaturated + aldehyde)
Selected AbstractsA Novel Method for the Synthesis of Substituted Benzochromenes by Ethylenediamine Diacetate-Catalyzed Cyclizations of Naphthalenols to ,,, -Unsaturated Aldehydes.HELVETICA CHIMICA ACTA, Issue 12 2007Concise Synthesis of the Natural Products Lapachenole, Dihydrolapachenole, Mollugin Abstract A new synthetic route for biologically interesting benzochromenes was developed starting from naphthalenols and ,,, -unsaturated aldehydes in the presence of ethylenediamine diacetate. This methodology was applied for the total synthesis of the biologically important natural products lapachenole, dihydrolapachenole, and mollugin with a benzochromene moiety. [source] Activated ,,,-Unsaturated Aldehydes as Substrate of Dihydroxyacetone Phosphate (DHAP)-Dependent Aldolases in the Context of a Multienzyme SystemADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009Israel Sánchez-Moreno Abstract The utility for carbon-carbon bond formation of a multienzyme system composed of recombinant dihydroxyacetone kinase (DHAK) from Citrobacter freundii, the fructose bisphosphate aldolase from rabbit muscle (RAMA) and acetate kinase (AK) for adenosine triphosphate (ATP) regeneration has been studied. Several aldehydes with great structural diversity, including three ,,,-unsaturated aldehydes, have been analysed as acceptor substrates. It was found that ,,,-unsaturated aldehydes bearing an electron-withdrawing group in the , position to the double bond with a trans configuration are good acceptors for RAMA in this multienzyme system. The aldol reaction proceeds with excellent D - threo enantioselectivity and the aldol adduct is obtained in good overall yield. The L - threo and D - erythro enantiomers are also accessible from rhamnulose 1-phosphate aldolase (Rha-1PA) and fuculose 1-phosphate aldolase (Fuc-1PA) catalysed reactions, respectively. [source] A Direct Amine-Palladium Acetate Cocatalyzed Saegusa Oxidation Reaction of Unmodified Aldehydes to ,,,-Unsaturated AldehydesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Jin Zhu Abstract A direct preparation of synthetically useful ,,,-unsaturated aldehydes from readily available aldehydes has been developed. The process is effectively cocatalyzed by an amine-palladium acetate to give rise to ,,,-unsaturated aldehydes in moderate to good yields (41,62%). The reaction features the use of unmodified aldehydes rather than enol silyl ethers, which are used in a typical Saegusa oxidation reaction. [source] An Efficient Enantioselective Method for Asymmetric Friedel,Crafts Alkylation of Indoles with ,,,-Unsaturated AldehydesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2009Liang Hong Abstract The Lewis base-Lewis base bifunctional catalytic system has been developed and successfully applied to the asymmetric Friedel,Crafts alkylation of indoles with ,,,-unsaturated aldehydes. The reactions are promoted by chiral diphenylprolinol trimethylsilyl ether in the presence of triethylamine. By this protocol, optically active 3-substituted indoles can be obtained in an organocatalytic process that is free of Lewis or protic acid in high yields with up to 98% ee. Besides, this reaction could be carried out on a gram scale without any loss in the enantioselectivity. [source] Enantioselective Michael Addition of Dicyanoolefins to ,,,-Unsaturated Aldehydes in Aqueous MediumADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2008Jun Lu Abstract A pool of water-compatible catalysts, namely dialkyl-(S)-prolinols, has been developed for the enantioselective direct vinylogous Michael addition reaction of vinylmalononitriles to ,,,-unsaturated aldehydes in aqueous medium. In many cases, the products can be obtained in almost optically pure form (>96% ee) after a single recrystallization. [source] Organocatalytic Asymmetric Formal [3+3],Cycloaddition Reactions of ,,,-Unsaturated Aldehydes with Nazarov ReagentsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2008Ming-Kui Zhu Abstract An organocatalytic asymmetric formal [3+3],cycloaddition reaction of ,,,-unsaturated aldehydes with Nazarov reagents promoted by prolinol derivatives afforded, after oxidation, 3,4-dihydropyranones in good yields with high enantioselectivities of up to 97% ee. [source] Amine-Catalyzed Asymmetric Epoxidation of ,,,-Unsaturated AldehydesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2007Gui-Ling Zhao Abstract The direct organocatalytic enantioselective epoxidation of ,,,-unsaturated aldehydes with different peroxides is presented. Proline, chiral pyrrolidine derivatives, and amino acid-derived imidazolidinones catalyze the asymmetric epoxidation of ,,,-unsaturated aldehydes. In particular, protected commercially available ,,,-diphenyl- and ,,,-di(,-naphthyl)-2-prolinols catalyze the asymmetric epoxidation reactions of ,,,-unsaturated aldehydes with high diastereo- and enantioselectivities to furnish the corresponding 2-epoxy aldehydes in high yield with up to 97:3 dr and 98,% ee. The use of non-toxic catalysts, water and hydrogen peroxide, urea hydroperoxide or sodium percarbonate as the oxygen sources could make this reaction environmentally benign. In addition, one-pot direct organocatalytic asymmetric tandem epoxidation-Wittig reactions are described. The reactions were highly diastereo- and enantioselective and provide a rapid access to 2,4-diepoxy aldehydes. Moreover, a highly stereoselective one-pot organocatalytic asymmetric cascade epoxidation-Mannich reaction, which proceeds via the combination of iminium and enamine activation, is presented. The mechanism and stereochemistry of the amino acid- and chiral pyrrolidine-catalyzed direct asymmetric epoxidation of ,,,-unsaturated aldehydes are also discussed. [source] Organocatalytic and Stereoselective [3 + 2] Cycloadditions of Azomethine Imines with ,,,-Unsaturated AldehydesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14 2006Wei Chen Abstract Bipyrazolidin-3-one derivatives are biologically significant compounds and their importance has increased in the past decades. In this paper, the first stereoselective [3 + 2] dipolar cycloadditions of azomethine imines with ,,,-unsaturated aldehydes catalyzed by readily available ,,,-diarylprolinol salts are reported, providing a facile route to the synthesis of various chiral bipyrazolidin-3-one derivatives under mild conditions. The organocatalyst 1,g with strongly electron-withdrawing groups exhibited the best stereoselectivity (exo:endo up to 98:2, for exo product up to 97,% ee), in the combination with trifluoroacetic acid. [source] Asymmetric Organocatalytic Cascade Reactions with ,-Substituted ,,,-Unsaturated Aldehydes,ANGEWANDTE CHEMIE, Issue 42 2009Patrizia Galzerano ,-Verzweigung erforderlich: Die erste hoch enantioselektive Aktivierung von ,-substituierten ,,,-ungesättigten Aldehyden mit einem Aminkatalysator wird vorgestellt. Das chirale primäre Amin 1 aktiviert selektiv ,-verzweigte Enale für eine Iminiumion/Enamin-Sequenz in Reaktionskaskaden aus Friedel-Crafts- oder Sulfa-Michael-Reaktion und Aminierung. Die hoch funktionalisierten Produkte mit zwei benachbarten Stereozentren werden mit hohen Enantiomerenüberschüssen isoliert. [source] Liquid-Phase Hydrogenation of Unsaturated Aldehydes: Enhancing Selectivity of Multiwalled Carbon Nanotube-Supported Catalysts by Thermal ActivationCHEMCATCHEM, Issue 2 2010Bruno Abstract Platinum and iridium organometallic precursors are used to prepare nanosized, thermally stable multiwalled carbon nanotube-supported catalysts. The materials are characterized by N2 adsorption at 77,K, temperature-programmed desorption coupled with mass spectrometry, H2 chemisorption, transmission electron microscopy and thermogravimetric analysis; they are tested in the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol under mild conditions (363,K and 1,MPa). A thermal activation at 973,K is found to have a very positive effect over both activity and selectivity, leading to selectivities of approximately 70,%, at 50,% conversion, regardless of the active metal phase (Pt or Ir). Since no noticeable differences in the metal particle sizes are detected, the results are interpreted in light of an enhanced metal/support interaction. This effect, induced by the removal of oxygenated surface groups, is thought to change the adsorption mechanism of the cinnamaldehyde molecule. [source] ChemInform Abstract: One-Step Synthesis of Thiazolo[3,2-a]pyridines by a Multicomponent Reaction of ,-Enaminonitriles, ,,,-Unsaturated Aldehydes, and 2-Aminothiol Hydrochlorides.CHEMINFORM, Issue 35 2010Monica Perez-Perrino Abstract Although the synthetic interest for the multicomponent preparation of the title thiazolopyridines is evident, the stereochemical control is rather low. [source] ChemInform Abstract: Catalytic Enantioselective 1,3-Dipolar Cycloaddition of C,N-Cyclic Azomethine Imines with ,,,-Unsaturated Aldehydes.CHEMINFORM, Issue 33 2010Takuya Hashimoto Abstract A titanium/(S)-BINOL complex catalyzes the title reaction of azomethine imines (I) to give a variety of pharmaceutically attractive chiral pyrazolo-fused tetrahydroisoquinolines. [source] ChemInform Abstract: Enantioselective Michael Addition to ,,,-Unsaturated Aldehydes: Combinatorial Catalyst Preparation and Screening, Reaction Optimization, and Mechanistic Studies.CHEMINFORM, Issue 19 2010Ivana Fleischer 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] ChemInform Abstract: The Organocatalytic Addition of Bis(arylsulfonyl)methane to ,,,-Unsaturated Aldehydes and the Synthesis of Optically-Enriched 3-Methyl-alkanols.CHEMINFORM, Issue 47 2009Jose Luis Garcia Ruano 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] ChemInform Abstract: Enantioselective Aziridination Reaction of ,,,-Unsaturated Aldehydes Using an Organocatalyst and tert-Butyl N-Arenesulfonyloxycarbamates.CHEMINFORM, Issue 40 2009Hiromi Arai 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] ChemInform Abstract: Organocatalytic Enantioselective Friedel,Crafts Alkylation of 4,7-Dihydroindoles with ,,,-Unsaturated Aldehydes: An Easy Access to 2-Substituted Indoles.CHEMINFORM, Issue 40 2009Liang Hong 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] ChemInform Abstract: Catalytic Enantioselective Construction of All-Carbon Quaternary Stereocenters by an Organocatalytic Diels,Alder Reaction of ,-Substituted ,,,-Unsaturated Aldehydes.CHEMINFORM, Issue 35 2009Taichi Kano 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] ChemInform Abstract: Enantioselective Methoxyselenenylation of ,,,-Unsaturated Aldehydes.CHEMINFORM, Issue 32 2009Claudio Santi 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] ChemInform Abstract: Catalytic Asymmetric Intramolecular Hydroarylations of ,-Aryloxy- and Arylamino-Tethered ,,,-Unsaturated Aldehydes.CHEMINFORM, Issue 28 2009Hai-Hua Lu 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] ChemInform Abstract: Selective Hydrogenation of Unsaturated Aldehydes in a Poly(ethylene glycol)/Compressed Carbon Dioxide Biphasic System.CHEMINFORM, Issue 6 2009Ruixia Liu 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] ChemInform Abstract: Enantioselective Organocatalytic Reactions of 4-Hydroxycoumarin and 4-Hydroxypyrone with ,,,-Unsaturated Aldehydes , An Efficient Michael Addition-Acetalization Cascade to Chromenones, Quinolinones and Pyranones.CHEMINFORM, Issue 2 2009Magnus Rueping 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] ChemInform Abstract: Organocatalytic Asymmetric Hydrophosphination of ,,,-Unsaturated Aldehydes: Development, Mechanism and DFT Calculations.CHEMINFORM, Issue 52 2008Ismail Ibrahem 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] ChemInform Abstract: Palladium Catalysts for the Formylation of Vinyl Triflates to Form ,,,-Unsaturated Aldehydes.CHEMINFORM, Issue 44 2008Helfried Neumann 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] ChemInform Abstract: Organocatalytic Asymmetric Formal [3 + 3] Cycloaddition Reactions of ,,,-Unsaturated Aldehydes with Nazarov Reagents.CHEMINFORM, Issue 44 2008Ming-Kui Zhu 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] ChemInform Abstract: An Efficient Enantioselective Method for Asymmetric Michael Addition of Nitroalkenes to ,,,-Unsaturated Aldehydes.CHEMINFORM, Issue 28 2008Yongcan Wang 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] ChemInform Abstract: Organocatalytic Asymmetric Cyclopropanation of ,,,-Unsaturated Aldehydes with Arsonium Ylides.CHEMINFORM, Issue 13 2008Yun-Hui Zhao 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] ChemInform Abstract: Nornicotine-Organocatalyzed Aqueous Reduction of ,,,-Unsaturated Aldehydes.CHEMINFORM, Issue 12 2008Andrew P. Brogan 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] ChemInform Abstract: An Efficient and Concise Synthesis of Biologically Interesting Pyranochromenes by Ethylenediamine Diacetate-Catalyzed Double Condensation of Substituted Trihydroxybenzenes to ,,,-Unsaturated Aldehydes and Application to Natural Product Analogues.CHEMINFORM, Issue 10 2008Yong Rok Lee 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] ChemInform Abstract: MgBr2 -Mediated Ionic Diels,Alder Reaction of Acetals of ,,,-Unsaturated Aldehydes and Ketones with 1,3-Dienes.CHEMINFORM, Issue 1 2008Subhash P. Chavan 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] One-Pot Synthesis of ,-Iodo-Substituted ,,,-Unsaturated Aldehydes from Propargylic Alcohols.CHEMINFORM, Issue 48 2007Shufeng Chen 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] | |||||||||||||||||||||||||||||||