Synthesis and adrenoceptor affinity of some highly polar beta-substituted catecholamines

In order to assess the potential for sympathomimetic or sympatholytic activity within the series of catecholamine beta-sulfonates 3a-c, alpha- and beta-adrenoceptor binding affinities were determined using rat brain homogenate preparations. Furthermore, their potential for indirect activity was assessed by measurement of blockade of norepinephrine uptake into rat synaptosomal preparations. Activity was uniformly low or nonexistent throughout the series. The possibility of unfavorable solution conformational distribution within the series was investigated by examination of the side chain vicinal 1H NMR coupling constants, but no differences that could account for the lack of affinity were found. The observed behavior may be due to receptor intolerance of the bulky beta-sulfonate substituent or an electronic mismatch in which normal H bonding is significantly altered.