Catalyst Study of the Knoevenagel Condensation.

Abstract

Several amino acids and aminophenols have been shown to be effective catalysts for the condensation of ketones with active methylene compounds (15). This study has now been extended to the condensation of seventeen aromatic and ten aliphatic aldehydes with ethyl cyanoacetate.

Solvent-Free Synthesis of 5-Benzylidene-2-Thioxothiazolidin-4-Ones and Thiazolidine-2,4-Diones Catalysed by Glycine under Microwave Irradiation

“…Glycine, the smallest of the amino acids, which is also non-toxic, non-corrosive and inexpensive, has been used to catalyse Knoevenagel condensation reactions in ionic liquid solvent. [14][15][16] We now suggest a novel, facile, and environmentally friendly method for the synthesis of 5-benzylidene-2-thioxothiazolidin-4-ones and thiazolidine-2,4-diones (3) by the condensation reaction of aromatic aldehydes (1) with rhodanine or thiazolidine-2,4-dione (2) under microwave irradiation without a solvent catalysed by glycine (Scheme 1).…”

Convenient Synthesis of Heterocyclic Azo Dyes in the Class of Pyranopyrazoles and Chromenes

“…(3a-f); general procedure Piperidine (5 mol%) was added to a solution of 5-(phenyldiazenyl) salicylaldehyde derivative 1 (5 mmol) and ethyl acetoacetate (0.65 g, 5 mmol) in ethanol (20 mL) under stirring and heating at 40 °C for 6-7 h. After cooling, the precipitate was filtered and washed with cold ethanol to afford pure product 3a-f in good yield. 9,121.5,122.6,126.6,129.5,138.2,146.5,151.3,155.5,171.5,194.2. Anal.…”

“…This reaction is usually catalysed by different weak and strong bases. [7][8][9][10] Knoevenagel condensation is utilised in the synthesis of chromene and pyranopyrazole moieties, which are key core substances in a variety of natural products and biological structures. [11][12][13][14][15] Figure 1 shows diverse compounds containing a pyranopyrazole or chromene nucleus with a variety of biological activities and pharmaceutical properties (A-D).…”

Synthesis and styrene copolymerization of novel ring-substituted isobutyl phenylcyanoacrylates

“…Trifluoromethoxy ring-substituted styrenes also reported in tuning the latent behavior of molybdenum imido alkylidene N-heterocyclic carbene complexes in dicyclopentadiene polymerization [12], in superbase-catalyzed anti-Markovnikov alcohol addition reactions to aryl alkenes [13], in study of effects of the chelating alkoxy ligand modifications on the structure and catalytic activity of ruthenium carbene complexes [14], in preparation of substituted anthranilic acids as potent dihydroorotate dehydrogenase inhibitors [15]. 2,4, cyanophenylacrylate is reported in study of the mass spectra of ethyl α-cyano-β-(2or 4substituted phenyl)acrylates [16] and in catalyst study of the Knoevenagel condensation [17]. Another similar compound, ethyl ester of 2-cyano-3-(2,4,6-trimethylphenyl)-2butenoic acid was used in preparation of ethyl α-cyano-β-(o-tolyl)acrylate and ethyl αcyano-β-methyl-β-mesitylacrylate [18].…”