6-Substituted 1,3,4,5-tetrahydrobenz[cd]indol-4-amines: potent serotonin agonists

Abstract
A series of 6-substituted tricyclic ergoline partial structures has been synthesized and found to possess very strong serotonin agonist activity. A methoxy group at the 6-position greatly enhances activity, but at the expense of compound stability. Substituting the 6-position with protophyllic groups that are also electron-withdrawing in character enhances both activity and stability.