Dopamine receptor ligands. Part VII [1]: novel 3-substituted 5-phenyl-1, 2, 3, 4, 5, 6-hexahydro-azepino-[4, 5-b]indoles as ligands for the dopamine receptors

A number of 5‐phenyl‐1, 2, 3, 4, 5, 6‐hexahydro‐azepino‐[4, 5‐b]indoles 3 were synthesized with different substituents at the azepine‐N position (methyl‐, allyl‐, 2‐phenyl‐ethyl‐, cyclopropylmethyl‐ and unsubstituted). Furthermore, the indole‐N‐methylated compound was generated and by using norephedrines and norpseudoephedrines as a chiral pool, 4‐methyl‐5‐phenyl‐1, 2, 3, 4, 5, 6‐hexahydro‐azepino‐[4, 5‐b]indoles were prepared which contained racemisation at the reacting C‐atom. These compounds, as well as the ring‐open amino‐alcohols, were screened for their affinity to the hD₁‐, hD₅‐, hD_2L‐, and hD₄‐receptors (ç please check sentence). They had micromolar affinities for the receptors and showed the highest affinity to the D₁‐subtype family. The cyclic compounds possessed the highest affinity, with the cyclopropylmethyl‐( 3c ) and methyl‐substituents ( 3e ) being the most active of the tested compounds. Based on an intracellular cAMP‐assay, the unsubstituted compound (at the azepine‐N position) turned out to be an agonist for the D₁‐and D₅‐subtype family, whereas the substituted compounds showed (partial) agonistic, or even inverse agonistic activity.