In one aspect, the invention relates to compounds having the formula: where R1-R6, a, b, and Z are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds 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.在一個態樣中,本發明係關於具有化學式I之化合物:其中R1-R6、a、b及Z係如說明書中所定義,或其醫藥上可接受的鹽。該等化合物具有腦啡肽酶抑制活性。在另一態樣中,本發明係關於包括該等化合物之醫藥組合物;利用該等化合物之方法;及製備該等化合物之方法及中間產物。