Nitro and amino substituted heterocycles as topoisomerase I targeting agents

摘要

The invention provides compounds of formula I: wherein: R₁-R₅, "a" and X 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, processes for preparing compounds of formula I, intermediates useful for preparing compounds of formula I, and therapeutic methods for treating cancer using compounds of formula I.