Comparative study of the synthesis of halogenated curcuminoids by two different methods

Abstract

Curcuminoids are natural or synthetic heptatrienones with a great biological interest due to their potential employment as anticancer, anti HIV and antioxidant agents. In laboratory, these compounds are obtained by means of aromatic aldehydes and actylacetone condensation. In this work, a comparative study of the four new curcuminoids synthesis is described by condensation of halogenated aromatic aldehydes and acetylacetone with two different methods. In the method A, the reaction mixture is developed in dimethylformamide during 4 h, at 85 ºC and 9-14 % of the final products were obtained. When the reaction was assisted by microwave. In the method B solvent was not used, the reaction time was just one minute and, the treatment of the reaction mixture with ultrasound facilitates considerably the isolation of the product by rupture of the complex-boron-curcuminoide at room temperature without using of acid conditions so that, the yield was achieved between 36 to 48 %. The method B was operationally simpler, showing economic and ecological advantages, which make it an attractive procedure for the synthesis of curcuminoids. All the synthesized compounds were characterized unequivocally by means of Nuclear Magnetic Resonance (NMR1-H) spectroscopy, quantitative elementary analysis and High Resolution Masse Spectrometry. In the spectrum RMN-1H of each one of compounds a singlet appears on 16 ppm corresponding to the hydroxylic proton from OH - enol group, which demonstrates that in these structures, the enol form is the most favoured.