| abstract |
The invention provides compounds of formula I or formula (II), wherein: the bond represented by --- is a single bond or a double bond, and R1-R5, X, and Y have any of the meanings defined in the specification and their pharmaceutically acceptable salts. The invention also provides pharmaceutical compositions comprising a compound of formula (I or II), processes for preparing compounds of formula (I or II), intermediates useful for preparing compounds of formula (I or II), and therapeutic methods for treating cancer and other topoisomerase related conditions using compounds of formula (I or II). |