2-(anilinomethyl)imidazolines as α1 adrenergic receptor agonists:: the discovery of α1a subtype selective 2′-alkylsulfonyl-substituted analogues

A series of 2'-alkylthio-2-(anilinomethyl)imidazolines were prepared to examine the effect of the alkyl group size, sulfur oxidation state, and phenyl ring substitution on ligand binding and agonism of alpha-adrenergic receptor subtypes alpha(1a), alpha(1b), alpha(1d), alpha(2a), and alpha(2c). Binding at all receptor subtypes decreased for compounds in the sulfone oxidation state as compared to their sulfide analogues. While sulfides were generally potent, nonselective agonists, sulfones exhibited alpha(1a) subtype selectivity in a cell-based functional assay. Sulfone (32) was 250-7000-fold selective for alpha(1a) vs all other subtypes.