7-Methyl-6,7,8,9,14,15-hexahydro-5H-benz[d]indolo[2,3-g]azecine: a new heterocyclic system and a new lead compound for dopamine receptor antagonists.

Partially hydrogenated derivatives of the new heterocyclic ring systems benz[d]indolo[2,3-g]-azecine and bisindolo[3,2-d][2,3-g]azecine were synthesized starting from lactones and amines via the described synthetic methods. In binding assays with rat striatal receptors, 7-methyl-6,7,8,9,14, 15-hexahydro-5H-benz[d]indolo[2,3-g]azecine (LE 300) proved to be of high affinity for the D-1 binding site (K-i = 0.08 nmol for displacement of [H-3]SCH23390), being superior in this assay to standards such as butaclamol and SCH23390. This compound was characterized as a dopamine antagonist by conditioned avoidance response test with mice. Thus, LE 300 represents the lead of a new class of dopamine antagonists for future investigations.