In one aspect, the invention relates to compounds having the formula:where R1, R2, R3, R7, R8, Z, X, b, and c are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds are nitric oxide donors and have neprilysin inhibition activity. In another aspect, the invention relates to pharmaceutical compositions comprising such compounds； methods of using such compounds； and processes and intermediates for preparing such compounds.
