Base Catalysis for Fine Chemicals Production: Claisen-Schmidt Condensation on Zeolites and Hydrotalcites for the Production of Chalcones and Flavanones of Pharmaceutical Interest

Chalcones and flavanones of commercial interest have been obtained with high yields and selectivities using solid base catalysts derived from hydrotalcites. The Al/(Al + Mg) ratio and hydrotalcite crystallite size are important parameters controlling catalyst activity. These catalysts give better results than acid- (HY) or alkaline-exchanged Y zeolites. An optimized hydrotalcite shows excellent catalytic properties for the synthesis of 2′,4,4′-trimethoxychalcone (Vesidryl), a product of pharmacological interest. The reactivity of substituted acetophenones and benzaldehyde follows the Hammet correlation. In addition to electronic effects, geometrical effects can also play a role in the reactivity of substituted acetophenones and benzaldehyde.