| 摘要 |
The present invention relates to a compound having the structure defined herein or a salt thereof, enantiomer or zwitterion, wherein bond α is absent; Rand Rare together =O; Ris O(CH)Ror OR, where Ris C-Caryl, and where Ris C-Calkyl, substituted C-Calkyl, C-Calkenyl, C-Calkynyl, substituted C-Caryl,orRiswhere X is NR, where each Ris C-Calkyl, C-Chydroxyalkyl, C-Calkenyl or C-Calkynyl; or Rand Rare different from each other and each is OH orRand Rare together =O; and Rand Reach is H. The invention also relates to a process for preparing the same, to a pharmaceutical composition comprising the same and to the use of the compound for the treatment of tumors. |
