This invention relates to: (a) compounds of Formula Ia (with R1, R4, R5, R6, n and A as defined herein) and pharmaceutically acceptable salts or solvates thereof that are useful as dopamine-β-hydroxylase inhibitors； (b) pharmaceutical compositions comprising such compounds, salts or solvates； (c) the use of such compounds, salts or solvates in therapy； (d) therapeutic methods of treatment using such compounds, salts or solvates； and (e) processes and intermediates useful for the synthesis of such compounds.
