Design,Synthesis and Biological Activity of (20S,21S)‐7‐Cyclohexyl‐21‐fluorocamptothecin Carbamates as Potential Antitumor Agents

(20S,21S)‐7‐Cyclohexyl‐21‐fluorocamptothecin was discovered by a fluorine drug design strategy with potent antitumor activity and increased metabolic stability. In continuous efforts to find novel antitumor agents derived from natural product camptothecin, 20‐carbamates of the active compound (20S,21S)‐7‐cyclohexyl‐21‐fluorocamptothecin have been designed and synthesized. Among them, one compound with the diethylamino group showed greater antiproliferative activity than the other 20‐carbamate derivatives. The following biological activity assays indicated that the above compound is a valuable lead compound with excellent Topo I inhibitory activity and solution stability.