Compounds of Formula 1 where X is S and the variables have the meaning defined in the specification are specific or selective to alpha.sub.2B and/or alpha.sub.2C adrenergic receptors in preference over alpha.sub.2A adrenergic receptors, and as such have no or only minimal cardiovascular and/or sedatory activity. These compounds of Formula 1 are useful as medicaments in mammals, including humans, for treatment of diseases and or alleviations of conditions which are responsive to treatment by agonists of alpha.sub.2B adrenergic receptors. Compounds of Formula 1 where X is O also have the advantageous property that they have no or only minimal cardiovascular and/or sedatory activity and are useful for treating pain and other conditions with no or only minimal cardiovascular and/or sedatory activity.