Synthesis and antitumor activity of 4-hydroxycoumarin derivatives

A series of 4-hydroxycoumarin derivatives was prepared and evaluated for antitumor activity. The key fragments were 2a–c, 5c, 12b, 13b, 17, and 18 which were prepared via dianion ring cyclization, Friedel–Crafts acylation, and Reformatsky reaction. Compound 20b showed the most potent antitumor activity among the total 12 derivatives and compounds 19a and 19b exhibited efficacy comparable to etoposide in vitro antitumor activity.