Ethylene glycol promoted catalyst-free pseudo three-component green synthesis of bis(coumarin)s and bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s (original) (raw)
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Green Chemistry Approach to the Synthesis of Biscoumarins from 4-Hydroxycoumarin
Croatica Chemica Acta
Numerous biological and pharmacological properties of coumarins have designated them as significant synthetic target in many fields. Biscoumarins are considered as an important class of coumarin derivatives that show remarkable pharmacological properties. Therefore, development of the efficient new methods for their synthesis, based on green methodology, would be of a great importance in medicinal and pharmaceutical chemistry. In this work, the ultrasound and microwave assisted synthesis of biscoumarins, starting from corresponding aldehydes and 4-hydroxycoumarin is reported. Molecular iodine was used as an efficient and inexpensive catalyst for a simple synthesis, to obtain excellent yields using ethanol as a solvent. It was found that 10 % (n/n) of molecular iodine catalyzes biscoumarin synthesis in high yields (80–94 %) and in short reaction times, using both ultrasound, as well as microwave promoted conditions. Furthermore, when those two methods are compared, ultrasound promote...
A simple one pot green highly efficient condition for synthesis of bis-coumarins involving simple grinding technique of 4-hydroxy coumarins and substituted aromatic aldehyde under solvent free condition, at room temperature catalysed by biodegradable, naturally occurring heterogeneous solid acid catalyst EPZ-10 has been described. The remarkable features of this environmentally benign protocol are short reaction time, use of commercially in expensive heterogeneous EPZ-10 catalyst by simple grinding technique at room temperate with high yield of product by simple experimental procedure.
Research on Chemical Intermediates, 2015
4-Phenyl and 3,4-dihydro-4-phenylcoumarins were prepared by direct esterification of phenols with phenylpropiolic and cinnamic acids, respectively, using a compound with Preyssler structure (H 14 P 5 NaW 30 O 110) (PA) as heterogeneous catalyst under solvent-free reaction conditions, at 130°C, in a short reaction time (2 h). Under these conditions, very good yields (11 examples: 61 %-90 %), free of secondary products, were obtained. The catalyst is recyclable, nontoxic, neither air nor moisture sensitive, and easy to handle. The described methodology is a clean and useful alternative to synthesize oxygenated heterocycles based on a coumarin skeleton.
Journal of Chemistry
Multicomponent cyclocondensation of hydrazine derivatives, ethyl acetoacetate, aromatic aldehydes, and 4-hydroxycoumarin has been reported. The optimization details of the developed novel protocol are recorded. The novel procedure features short reaction time, moderate yields, and simple workup. In addition, BMIM[triflate] was chosen as a green solvent. The structures of the obtained benzylpyrazolyl coumarins were determined and confirmed by 1H NMR, 13C NMR, IR, and elemental analysis. The MIC values of benzylpyrazolyl coumarin derivatives were determined by the microbroth dilution method using 96-well plates. However, the derivatives 5a, 5b, 5d, and 5g possess the strongest activities. Compound 5b was the most active derivative against Candida albicans. Moreover, the antioxidant activity determination of these coumarins derivatives 5(a–g)–6(a–g) were studied with the DPPH and compared with gallic acid (GA)and butylated hydroxytoluene (BHT). Molecular modelling studies using DFT (de...
Catalysis Communications, 2008
Coumarin-3-carboxylic acids and 3-acetyl-coumarins were obtained in high yields with excellent purity from ortho-hydroxybenzaldehydes and 1-ethylacetoacetate or malonic acid after a 2 h reflux in ethanol in the presence of a catalytic amount of different heteropolyacids (HPAs). The less reactive 1-(2-hydroxy-phenyl)-ethanone was first reacted with alcoholic ammonia to form ketimines, which were then condensed with 1-ethylacetoacetate or malonic acid to generate 4-methyl coumarin-3-carboxylic acids and 4-methyl 3-acetyl-coumarins in moderate yields.
Journal of Heterocyclic Chemistry, 2014
A series of 50 novel 7-[2-hydroxy-3-(1,2,3-triazol-1-yl)propyloxy]-3-alkyl-4-methylcoumarins had been designed and synthesized in good to excellent yields via Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction "click chemistry" of 7-(3-azido-2-hydroxypropyloxy)-3-alkyl-4-methylcoumarins with variety of acetylene derivatives. In turn, the precursor compound, that is, 7-(3-azido-2-hydroxypropyloxy)-3-alkyl-4-methylcoumarin, was synthesized by condensation of epichlorohydrin with 7-hydroxy-3-alkyl-4-methylcoumarins followed by opening of the epoxide ring in the resulted 7-epoxymethoxy-3-alkyl-4-methylcoumarins with sodium azide. All the synthesized compounds were unambiguously identified on the basis of their spectral data analyses (IR, 1 H-NMR, 13 C-NMR spectra, and HRMS).