3,5-Dimethoxybenzyl bromide (4) reacted with sodium cyanide to form 3,5-dimethoxybenzyl nitrile (5), which was transformed into 3,5-dimethoxyphenylacetic acid (6) via hydrolysis. The Knoevenagel reaction between 5 and benzaldehyde or its deriva-tives afforded 2a～2d, which were all Z-isomers. The Perkin reaction between 6 and benzaldehyde or its derivatives afforded 3a～3c, which were all E-isomers. 2a～2d and 3a～3c all are the analogues of resveratrol 1. The structures of the products of every step reaction were charaterized by IR, ¹H NMR, ¹³C NMR and MS spectra. The factors of affecting the reactions were discussed. Compounds 2a～2d and 3a～3c were tested in vitro for their antitumor activity on breast tumor cells MCF-7, lung tumor cells H446, breast tumor cells 231 and their toxicity on normal liver cells L02. Their IC₅₀ values were given.

Key words: 3,4',5-trihydroxy-trans-stilben, biological evaluation, resveratrol analogues