Synthesis of Andrographolide Cyclophosphate Derivatives and Their Antitumor Activities

Abstract A series of cyclophosphate andrographolide derivatives were synthesized from andrographolide, the cytotoxic constituent of the plant Andrographis paniculata. The derivative (PR, P′S)‐5 and (PS, P′S)‐6 were synthesized and the proposed mechanism for their formation was discussed. The structures of all compounds were elucidated by IR, NMR, MS (ESI), and HR‐MS. The stereochemistry of 6 was confirmed by X‐ray analysis. All the derivatives were tested for antitumor activity in vitro, and some of them showed good results.