Novel 5-(3-(Substituted)-4,5-dihydroisoxazol-5-yl)-2-methoxyphenyl Derivatives: Synthesis and Anticancer Activity

Thirty novel 5-(3-(substituted phenyl)-4,5-dihydroisoxazol-5-yl)-2-methoxyphenyl derivatives were synthesized and evaluated for their antitumour activity. The bioassays showed that the 2-fluorobenzoyl derivative 6ai, the 4-trifluoromethylbenzoyl derivative 6ah, and the 3-trifluoromethyl isoxazole derivatives (6ch and 6ci) were highly effective against PC-3 cells. The IC50 values of 6ah and 6ai against PC-3 cells were 1.5 and 1.8 μg mL–1, respectively.

Synthesis of new steroidal isoxazoles: inhibitors of estrogen synthase

A novel class of steroidal A/B ring isoxazoles have been prepared by two independent reaction schemes using 3 beta,17 beta-diacetoxyandrost-5-ene (1) and 3 beta,17 beta-diacetoxyandrost-4-en-6-one (4) as synthetic precursors. The key common intermediate in these syntheses, 3 beta,17 beta-diacetoxyandrost-4-eno[6,5,4-c,d] isoxazole (3), was prepared by synthetic methods described in both schemes. Further chemical modification of 3 yielded 3 beta,17 beta-dihydroxyandrost-4-eno[6,5,4-c,d] isoxazole (6), androst-3,17-dione-4-eno[6,5,4-c,d] isoxazole (7), and 17 beta-hydroxyandrost-3-one-4-eno[6,5,4-c,d] isoxazole (9). Human placental estrogen synthase (aromatase) bioassays were conducted to obtain the following IC50 values resulting from a 50% reduction of enzymatic activity: 6, 120.5 microM; 7, 1.889 microM. 9, 18.57 microM.