Cantharidine is known to have certain degree of efficacy for the treatment of cancer. The adverse effects on urinary and gastrointestinal tracts prevent it to be accepted by the clinic. The structural modification of cantharidine is pursued by the authors with the aim to decrease its toxicity and increase its efficacy. Thirty one derivatives of Cantharidine with the following types Ⅲ, Ⅳ, Ⅴ, Ⅵ were synthesized. The compounds prepared were listed in tables 1~4Compounds 1~5 were obtained by condensation of Can...