| abstract |
The present invention provides a compound of formula (I) and pharmaceutically acceptable salts thereof. The present invention also provides pharmaceutical compositions comprising the compounds of formula (I), methods of preparing compounds of formula (I), intermediates useful for preparing compounds of formula (I), and methods of treating cancer using the compounds of formula (I).n n n <Formula I>n n n n n n n n In the formula, A, B, W, Y, Z and R 1 have any meanings defined in the specification. |