A rhodium-catalyzed dehydrogenation protocol for the conversion of 3,5-diarylcyclopentenones to the corresponding 2,4-diarylcyclopentadienones has been developed. With this protocol, analogues of the cytotoxic agent chamaecypanone C have been synthesized via Diels-Alder cycloaddition between the cyclopentadienones and in situ-generated o-quinols. Biological evaluation of these analogues revealed a compound with higher activity as a microtubule inhibitor and cytotoxic agent in comparison with the parent structure.