Synthesis and in vitro structure-activity relationship of 13-tert-butyl-ergoline derivatives as 5-HT1A receptor ligands

A series of novel 13-tert-butyl-ergoline derivatives was prepared and evaluated for affinity to adrenergic, dopaminergic and serotonergic receptor sites. Selectivity for 5-HT1A receptors versus alpha(1), alpha(2), D-1, D-2, and 5-HT2 appears to be influenced by the presence of the tert-butyl moiety at position 13 of the ergoline skeleton. Some compounds within this series display nanomolar 5-HT1A affinity and hundred-fold selectivity versus the other receptors considered.