This work describes the syntheses and antitumoral properties of five prenyl compounds from which antiproliferative activities were predicted by using the TOPS-MODE approach, a computational method for drug design. The syntheses of 2-(3-methylbut-2-enyloxy)acetophenone (2), 2-hydroxy-5-(3-methylbut-2-enyl)acetophenone (3), 2-hydroxy-3-(1,1-dimethylallyl)acetophenone (4), and 5-(3-methylbut-2-enyl)-2-(3-methylbut-2-enyloxy)acetophenone (5) were realized by O-prenylation of phenolic compounds with prenyl bromide and by Claisen rearrangement, respectively. Reaction of 2-hydroxy-5-(3-methylbut-2-enyl)acetophenone 3 under Vilsmeier-Haack conditions with phosphoryl chloride and N,N-dimethylformamide yielded 6-(3-methylbut-2-enyl)chromone-3-carbaldehyde (6). The compounds were tested for their cytotoxicity toward a diverse panel of cultured human tumor cell lines. Compound 3 showed significant selective cytotoxic activity (IC(50) < 9 microg/ml).