Knoevenagel Condensation (knoevenagel + condensation)

Distribution by Scientific Domains


Selected Abstracts


Synthesis of Ionic Liquid Functionalized SBA-15 Mesoporous Materials as Heterogeneous Catalyst toward Knoevenagel Condensation under Solvent-Free Conditions

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2006
Yong Liu
Abstract 1-Methyl-3-propylimidazolium chloride (MPImCl) and 1-propylpyridinium chloride (PPyCl) ionic liquid functionalized SBA-15 mesoporous materials were synthesized and used as heterogeneous catalysts in Knoevenagel reactions with excellent yields and reusability. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]


Nitrogen-Doped Carbon Materials Prepared by Ammoxidation as Solid Base Catalysts for Knoevenagel Condensation and Transesterification Reactions

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010
Naokatsu Kan-nari
Abstract Nitrogen-doped carbon materials were prepared by ammoxidation of commercial carbon sources (carbon black and activated carbon) and applied as base catalysts for Knoevenagel and transesterification reactions. It was shown that these carbon materials were active and the activities were different depending on the ammoxidation conditions (temperature and ammonia concentration in air) and carbon sources used. The bulk, textural, and surface properties of the nitrogen-doped carbon materials were examined by several methods to clarify possible factors determining their final catalytic activities. The activated carbon-derived catalysts were more active than the carbon black-derived ones. The surface area and porosity were not responsible for this difference between the two carbon sources but the difference in the reactivity with oxygen was important. The reactivity of carbon sources with oxygen should influence the doping of nitrogen onto their surfaces by ammoxidation with ammonia and air and the resulting activities as base catalysts. The catalytic activity increases with the amount of nitrogen doped and, therefore, the nitrogen doped should be responsible for the catalytic activities. In addition, the activities are maximal at a ratio of nitrogen to oxygen of around 1, suggesting the importance of cooperative functions of nitrogen and oxygen on the surface of carbons. [source]


ChemInform Abstract: Efficient Three-Component One-Pot Synthesis of Fully Substituted Pyridin-2(1H)-ones via Tandem Knoevenagel Condensation,Ring-Opening of Cyclopropane,Intramolecular Cyclization.

CHEMINFORM, Issue 42 2009
Fushun Liang
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: Knoevenagel Condensation of ,,,-Unsaturated Aromatic Aldehydes with Barbituric Acid under Non-Catalytic and Solvent-Free Conditions.

CHEMINFORM, Issue 19 2008
Cherkupally Sanjeeva Reddy
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]


An Expeditious Approach to Knoevenagel Condensation of Meldrum,s Acid on Neutral Alumina Using Microwave Irradiation.

CHEMINFORM, Issue 22 2007
Manas Chakrabarty
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]


On Water: An Efficient Knoevenagel Condensation Using 12-Tungstophosphoric Acid as a Reusable Green Catalyst.

CHEMINFORM, Issue 10 2007
Hossien A. Oskooie
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]


A Convenient One-Pot Synthesis of Benzopyrimido[1,8]naphthyridines by Knoevenagel Condensation.

CHEMINFORM, Issue 35 2005
R. Nandha Kumar
No abstract is available for this article. [source]


Solid State Synthesis of Substituted Coumarin-3-carboxylic Acids via the Knoevenagel Condensation under Microwave Irradiation.

CHEMINFORM, Issue 7 2005
Majid M. Heravi
No abstract is available for this article. [source]


ChemInform Abstract: Natural Phosphate Doped with Potassium Fluoride and Modified with Sodium Nitrate: Efficient Catalysts for the Knoevenagel Condensation.

CHEMINFORM, Issue 27 2002
Said Sebti
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: Microwave Assisted Knoevenagel Condensation: A Facile Method for the Synthesis of Chalcones.

CHEMINFORM, Issue 2 2002
G. Venkat Reddy
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: Synthesis of 2-Trifluoromethylthioacrylate and Its Derivatives via the Knoevenagel Condensation.

CHEMINFORM, Issue 23 2001
Elsa Anselmi
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: High Catalytic Activity of As-Synthesized, Ordered Porous Silicate,Quaternary Ammonium Composite for Knoevenagel Condensation.

CHEMINFORM, Issue 1 2001
Yoshihiro Kubota
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: First Example of Organocatalysis by Polystyrene-Supported PAMAM Dendrimers: Highly Efficient and Reusable Catalyst for Knoevenagel Condensations.

CHEMINFORM, Issue 3 2009
G. Rajesh Krishnan
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]


Synthesis and Reactivity of , -Electron-Deficient (Arylsulfonyl)acetates

HELVETICA CHIMICA ACTA, Issue 12 2002
Diego
Different , -electron-deficient (arylsulfonyl)acetates 9 were synthesized (Scheme,1, Table,1), and their behavior as soft nucleophiles in the dialkylation reaction under phase-transfer catalysis conditions was studied (Schemes,2 and 3, Tables,2 and 3). The [3,5-bis(trifluoromethyl)phenyl]sulfonyl group was shown to be the best substituent for the stereoselective synthesis of (E)-aconitates 18via an alkylation hydro-sulfonyl-elimination integrated process under very mild phase-transfer-catalysis conditions (Scheme,5, Table,4). Sulfonylacetates 9h,i also underwent smooth Diels-Alder reactions with acyclic and cyclic dienes via in situ formation of the appropriate dienophile through a Knoevenagel condensation with paraformaldehyde (Scheme,6). Reductive desulfonylation with Zn and NH4Cl in THF was shown to be an efficient method for removal of the synthetically useful sulfonyl moiety (Scheme,7). [source]


Facile, efficient, and eco-friendly synthesis of benzo[b]pyran-2-imines over MgO and transformation to the coumarin derivatives

JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2009
Hassan Valizadeh
Room temperature synthesis of benzo[b]pyran-2-imine derivatives via the Knoevenagel condensation of malononitrile and cyanoacetates with salicylaldehyde derivatives over MgO and their transformation to the known coumarins is described. The satisfactory results were obtained with good yields, short reaction time, and simplicity in the experimental procedure. J. Heterocyclic Chem., (2009). [source]


tert -Amino effect at a coumarin and a 2-quinolone system: Synthesis of 1,2 fused 5H -chromeno[4,3- b]pyridin-5-ones and a 6H -benzo[h][1,6]naphthyridin-5-one

JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2008
Ivo C. Ivanov
Some novel 1,2-fused 5H -chromeno[4,3- b]pyridin-5-ones (5a,b) and a 6H -benzo[h][1,6]naphthyridin-5-one (5c) have been synthesized starting from the 4-chlorocoumarin-3-carbaldehyde (1a) or its N -methyl-2-quinolone analogue (1b) via subsequent Knoevenagel condensation and ring closure reaction known as the ,tert -amino effect'. These are rare examples of the tert -amino effect occurring at 2-pyrone and 2-pyridone ring. An unusual intramolecular redox reaction of the iminium ion 6, reported earlier, most probably follows analogous mechanism as the tert- amino effect reactions leading to 5. [source]


Synthesis and characterization of polyfluorenevinylene with cyano group and carbazole unit

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2009
Suhee Song
Abstract The present investigation deals with the synthesis, characterization, and EL properties of new polyfluorenevinylenes, CzCNPFVs, with cyano-substituted vinylene unit and carbazole pendant. In CzCNPFVs, synthesized by the Knoevenagel condensation, the carbazole pendant was introduced to improve the efficiency of reported CNPFV. The PL emission spectra of the CzCNPFVs in chloroform solution show maximum peaks at 476,479 nm. In thin films, maximum peaks of the CzCNPFVs appeared at 501,504 nm, red-shifted around 25 nm as compared to those in solution. The emission maxima of the EL spectra of the polymers appear at around 496,504 nm. The maximum luminescence (Lmax) of CzCNPFV2 of the device with the configuration of ITO/PEDOT/CzCNPFVs/Ca/Al is 1724 cd/m2 at 8 V. The maximum luminescence efficiency of CzCNPFV1 is 0.18 cd/A. 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6540,6551, 2009 [source]


Liquid crystalline conjugated polymers and their applications in organic electronics

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2009
Sheng-Hsiung Yang
Abstract This article describes the syntheses and electro-optical applications of liquid crystalline (LC) conjugated polymers, for example, poly(p -phenylenevinylene), polyfluorene, polythiophene, and other conjugated polymers. The polymerization involves several mechanisms: the Gilch route, Heck coupling, or Knoevenagel condensation for poly(p -phenylenevinylene)s, the Suzuki- or Yamamoto-coupling reaction for polyfluorenes, and miscellaneous coupling reactions for other conjugated polymers. These LC conjugated polymers are classified into two types: conjugated main chain polymers with long alkyl side chains, namely main-chain type LC polymers, and conjugated polymers grafting with mesogenic side groups, namely side-chain type LC conjugated polymers. In general, the former shows higher transition temperature and only nematic phase; the latter possesses lower transition temperature and more mesophases, for example, smectic and nematic phases, depending on the structure of mesogenic side chains. The fully conjugated main chain promises them as good candidates for polarized electroluminescent or field-effect devices. The polarized emission can be obtained by surface rubbing or thermal annealing in liquid crystalline phase, with maximum dichroic ratio more than 20. In addition, conjugated oligomers with LC properties are also included and discussed in this article. Several oligo-fluorene derivatives show outstanding polarized emission properties and potential use in LCD backlight application. 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2713,2733, 2009 [source]


Synthesis of ,- and ,-Pyran Naphthoquinones as a New Class of Antitubercular Agents

ARCHIV DER PHARMAZIE, Issue 2 2010
Sabrina B. Ferreira
Abstract A series of ,- and ,-pyran naphthoquinones (lapachones) have been synthesized and evaluated for their in-vitro antibacterial activity against Mycobacterium tuberculosis strain H37Rv (ATCC 27294) using the Alamar-Blue susceptibility test; the activity was expressed as the minimum inhibitory concentration (MIC) in ,g/mL. The synthetic methodology consisted of the formation of methylene and aryl o -quinone methides (o -QMs) generated by Knoevenagel condensation of 2-hydroxy-1,4-naphthoquinone with formaldehyde and arylaldehydes. These o -QMs then undergo facile hetero Diels,Alder reactions with dienophiles in aqueous ethanol media. Some naphthoquinones exhibited inhibition with MIC values of 1.25 ,g/mL, similar to that of pharmaceutical concentrations currently used in tuberculosis treatment. These results justify further research into the value of these quinones as part of an original treatment for tuberculosis. [source]


ChemInform Abstract: Regioselective Synthesis of Highly Functionalized 3-Spiropyrrolidine/Pyrrolizidine Oxindoles and Acenaphthenones via One-Pot Four-Component [3 + 2] Cycloaddition.

CHEMINFORM, Issue 42 2010
Kai Zhao
Abstract Novel dipolarophiles, prepared in situ by Knoevenagel condensation of cyanoacetylindole (II) and aldehydes, undergo 1,3-dipolar cycloaddition with azomethine ylides derived from diketones and amino acids to yield highly functionalized spiro compounds. [source]


Versatile 2-aminothiazoles, building blocks for highly functionalised heterocycles

JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2003
Gerd Kaupp
The reactions of quantitatively available 4-phenyl- and 4-(4-antipyrinyl)-2-aminothiazole ["4-antipyrinyl-" is used as a short-term for "4-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1-H-pyrazol-4yl)-"] with chloroacetyl chloride, acetic anhydride, ethyl cyanoacetate and carbon disulphide are reported. The products are transformed further by Knoevenagel condensations and coupling reactions with aromatic diazonium salts. The latter occur both at the thiazole ring and at the active methylene sites. The tautomerism of these products is studied on the basis of density functional theory calculations at the B3LYP/6-31G* level. [source]