US Patent 6908918 Antitumor agents

The present invention provides compounds of general formula I or II:wherein R1, R2, R3, R4, R5, R6, and R7 have any of the values defined in the specification, and pharmaceutically acceptable salts thereof, as well as pharmaceutical compositions comprising compounds of formula I or II, intermediates and processes useful for preparing compounds of formula I or II, and methods comprising inhibiting tumor growth or treating cancer by administering one or more compounds of formula I or II.