Series of diaryl ethers, amines and amides have been synthesized and tested for antitumor activity. These diaryl compounds possess some of the structural features of combretastatin A-4 (a potent antimitotic agent). They were designed to discover whether transferring these structural motifs from stilbenes to heterosubstituted diaryl compounds would enhance their biochemical activities. Molecular modeling studies suggested that these diaryl compounds could adopt conformations similar to combretastatin A-4. However, although some agents (5-7) were cytotoxic and others (10 and 12) could interact with tubulin, none were as potent as combretastatin A-4.