Conformational analysis of optically active phenylethylamines and phenylimidazolines.

Conformational and structural features of phenethylamine and phenylimidazoline derivatives with alpha-adrenergic activity have been studied by MNDO and PCILO methods. From the calculated conformational energy maps, we conclude that phenethylamines exhibit an extended conformation, while the phenylimidazolines adopt a position intermediate between that of corresponding extended and folded conformations. We conclude that the phenethylamines interact with classical Easson-Stedman sites, while the phenylimidazolines interact with a different site. Both phenethylamines and phenylimidazolines show similar requirements for a cationic recognition site.