The invention provides compounds of formula (I): and salts thereof wherein ring A, R2, HET, X, n, and R3 have any of the meanings described in the specification, as well as compositions comprising such compounds and salts, and methods for treating cancer using such compounds and salts.
The invention provides compounds of formula (I): and salts thereof wherein ring A, R
2
, HET, X, n, and R
3
have any of the meanings described in the specification, as well as compositions comprising such compounds and salts, and methods for treating cancer using such compounds and salts.