Inhibitors of the renal outer medullary potassium channel

A compound having structural Formula I:

• or a pharmaceutically acceptable salts thereof wherein:
• Z1 is
• wherein the dashed line represents an optional double bond;
• Z2 is
• R1 is —H, —CH3, —CF3, —CHF2, —CH2F or —CH2OH;
• R2 is —H, oxo or —C1-6alkyl;
• R4 is —H, —OH, oxo, —F or —C1-6alkyl;
• provided that when R4 is —OH, oxo or —F, then R2 is not oxo;
• R6 is —H, —OH, oxo, —F or —C1-6alkyl;
• R8 is —H, oxo or —C1-6alkyl;
• provided that when R6 is —OH, oxo or —F, then R8 is not oxo;
• R3, R5, R7, and R9 are each independently —H or —C1-6alkyl;
• provided that R3 is absent when R2 is oxo, R5 is absent when R4 is oxo, R7 is absent when R6 is oxo, and R9 is absent when R8 is oxo;
• R1a is —H, halo or —C1-3alkyl optionally substituted with one to three of —F;
• one of R1b and R1c is —CN, —NO2 or tetrazolyl, and the other is —H, halo, —O—C1-3alkyl, —COOC1-3alkyl or —C1-3alkyl optionally substituted with one to three of —F;
• one of R1d, R1e and R1f is —CN, —NO2 or tetrazolyl, and each of the others is independently —H, halo, —O—C1-3alkyl, —COOC1-3alkyl or —C1-3alkyl optionally substituted with one to three of —F;
• R2a is —H, halo or —C1-3alkyl optionally substituted with one to three of —F;
• one of R2b and R2c is —CN, —NO2 or tetrazolyl, and the other is —H, halo, —O—C1-3alkyl, —COOC1-3alkyl or —C1-3alkyl optionally substituted with one to three of —F;
• one of R2d, R2e and R2f is —CN, —NO2 or tetrazolyl, and each of the others is independently —H, halo, —O—C1-3alkyl, —COOC1-3alkyl or —C1-3alkyl optionally substituted with one to three of —F;
• and
• Ra and Rb are each independently —H, halo, —O—C1-3alkyl, —COOC1-3alkyl or —C1-3alkyl optionally substituted with one to three of —F.