Addition of ethylmagnesium bromide to 3,4,5-trimethoxybenzaldehyde (I) gave secondary alcohol (II), which was converted into ketone (III) by Swern oxidation with DMSO and oxalyl chloride. Piperidinium acetate-catalyzed aldol condensation of propiophenone (III) with 3-hydroxy-4-methoxybenzaldehyde (IV), with water removal over 4 ?molecular sieves, gave the corresponding chalcone, obtained as a mixture of geometric isomers, from which the major E-isomer was separated by column chromatography.