Further structure–activity relationship studies on 8-substituted-3-[2-(diarylmethoxyethylidenyl)]-8-azabicyclo[3.2.1]octane derivatives at monoamine transporters

Abstract

The synthesis and structure–activity relationships of 8-substituted-3-[2-(diarylmethoxyethylidenyl)]-8-azabicyclo[3.2.1]octane derivatives were investigated at the dopamine transporter (DAT), the serotonin transporter (SERT) and norepinephrine transporter (NET). The rigid ethylidenyl-8-azabicyclic[3.2.1]octane skeleton imparted modestly stereoselective binding and uptake inhibition at the DAT. Additional structure–activity studies provided a transporter affinity profile that was reminiscent of the structure–activity of GBR 12909. From these studies, the 8-cyclopropylmethyl group has been identified as a unique moiety that imparts high SERT/DAT selectivity. In this study the 8-cyclopropylmethyl derivative 22e (DAT Ki of 4.0nM) was among the most potent compounds of the series at the DAT and was the most DAT selective ligand of the series (SERT/DAT: 1060). Similarly, the 8-chlorobenzyl derivative 22g (DAT Ki of 3.9nM) was found to be highly selective for the DAT over the NET (NET/DAT: 1358).