Synthesis and antitumor activity of tropolone derivatives.

Treatment of tropolones with benzaldehyde diethyl acetals gave monotropolone (12) and bistropolone (13) derivatives at the benzylic position, whereas the related 1-ethoxyisochroman and the diethyl acetals of crotonaldehyde and cinnamaldehyde gave only the monotropolone derivatives (5, 10, or 11). The monotropolone derivatives (5, 10, 11, and 12) had poor potency against P388 leukemia in mice, but the bistropolone derivatives (13 and 14) showed significant potency and prolongation of life.