Troponoids. 6. Troponylpiperazines: a new class of dopamine agonists.

A series of alkyltroponylpiperazine derivatives was synthesized and evaluated for dopaminergic activity in rats rendered hypokinetic by the bilateral injection of 6-hydroxydopamine (6-OHDA) into the anterolateral hypothalamus. Several members of the series were active, and a structure-activity relationship is presented. A few selected compounds were also evaluated with regard to their ability to induce contralateral rotational behavior in rats with a unilateral 6-OHDA-induced lesion of the nigrostriatal dopamine pathway. The compounds were compared to bromocriptine. The results indicate that dopaminergic activity is very sensitive to small changes in the troponylpiperazine moiety.