Synthesis and monoamine transporter affinity of front bridged tricyclic 3β-(4′-halo or 4′-methyl)phenyltropanes bearing methylene or carbomethoxymethylene on the bridge to the 2β-position

A series of front bridged tricyclic 3β-(4′-halo or 4′-methyl)phenyltropanes bearing methylene or carbomethoxymethylene on the bridge to the 2β-position was synthesized, and their binding affinities were determined in cells transfected to express human norepinephrine transporter (NET), serotonin transporter (SERT), and dopamine transporter (DAT) via competition binding assays. All compounds studied in this series exhibit a moderate to high potency at all three transporters with SERT or DAT selectivity. 3β-(4′-iodo)phenyltropane bearing methylene on the bridge to the 2β-position (24) presents a particularly attractive pharmacological profile, with very high SERT affinity (Ki = 0.09 nM) and selectivity versus NET (65-fold) and DAT (94-fold).