Abstract
The preferred conformation of noradrenaline has been calculated using extended Hückel molecular orbital theory. The conformation was found to be identical to the previously calculated conformation of (—)-ephedrine in respect to the relation of the quaternary and hydroxyl groups and the phenyl ring. These findings reinforce the previous hypothesis of the nature of the α-adrenergic receptor and also support the view that these molecules function at the receptor in their preferred conformations.