β-Adrenergic blocking agents: Substituted phenylalkanolamines. Effect of side-chain length on β-blocking potency in vitro

Article abstract of DOI:10.1021/jm00373a003

The synthesis of a group of potential β-blockers bearing a new 5-ethoxysalicylamide substituent on nitrogen is described. These compounds were tested for β-adrenergic blocking potency in vitro and compared with analogous compounds bearing a tert-butyl group on nitrogen. The new N-substituent increased the β-blocking potency substantially. In a series of five homologous compounds of the type Ar(CH₂)(n)CHOHCH₂NHR (R = 5-ethoxysalicylamide; n = 0-4), two maxima of β-blocking potency were found for n = 0 and 2. Moreover, the carbon isostere of the corresponding (aryloxy)propanolamine still proved to be a very potent β-blocker. The ether oxygen in the side chain is therefore not an absolute requirement for activity. Structure-activity relationships are discussed.