Knoevenagel condensation of aromatic aldehydes with ethyl 4-chloro-3-oxobutanoate in ionic liquids

Journal of the Brazilian Chemical Society

Bruno R. S. De Paula²  Dávila S. Zampieri²  Julio Zukerman-schpector¹  Edward R. T. Tiekink¹  José Augusto R. Rodrigues²  Paulo J. S. Moran² 

[1] ,University of Campinas Institute of Chemistry Campinas SP ,Brazil

关键词: Knoevenagel condensation;    ethyl 4-chloro-3-oxobutanoate;    ionic liquid;    ethyl (E/Z)-2-chloroacetyl-3-arylpropenoate;   

DOI  :  10.1590/S0103-50532012000500006

来源: SciELO

【 摘 要 】

Knoevenagel condensations of aromatic aldehydes with ethyl 4-chloro-3-oxobutanoate catalyzed by morpholine/acetic acid were carried out in ionic liquids to give ethyl 2-chloroacetyl-3-arylpropenoates in 44-84% yield after 0.5 to 2 h at room temperature (25-28 ºC). These conditions represent a greener protocol for the Knoevenagel condensation than those using refluxing benzene or toluene as solvent. Aromatic aldehydes having aryl groups 4-chlorophenyl, 4-methoxyphenyl, 2-thiofuranyl, 2-furanyl, phenyl and 3,4-methylenedioxyphenyl gave (E)/(Z) diastereomeric ratios of products from 56/44 to 85/15. The two isomers of each compound were separately isolated and characterized. The structure of the (E)-isomer of ethyl 2-chloroacetyl-3-(3',4' methylenedioxyphenyl)propenoate was determined by X-ray crystallography and an unequivocal methodology of (E)/(Z)-structural analysis by 13C NMR (nuclear magnetic resonance) is presented.

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