| abstract |
The invention provides compounds of formula I: n nwherein R 1 to R 5 have any of the values defined in the specification, as well as pharmaceutically acceptable salts of the compounds, pharmaceutical compositions comprising the compounds, and methods of using the compounds, compositions, or salts to treat cancer. In embodiments, R 4 and R 5 taken together can be a 3, 4, or 5 membered saturated or unsaturated chain comprising members selected from the group consisting of non-peroxide oxygen, sulfur, N(X), and carbon, optionally substituted by oxo; wherein each X is independently absent or is H, O, (C 1 –C 4 )alkyl, phenyl or benzyl; and wherein at least one of the chain members is an N—H group. |