Synthesis and monoamine transporter affinity of 3′-analogs of 2-β-carbomethoxy-3-β-(4′-iodophenyl)tropane (β-CIT)

The 3′-iodo positional isomer of 2-β-carbomethoxy-3-β-(4′-iodophenyl)tropane (β-CIT) and other 3′-substituted analogs were synthesized and evaluated for binding to monoamine transporters in rat forebrain and membranes of cell lines selectively expressing human transporter genes. All 3′-substituted compounds displayed affinity for both serotonin (SERT) and dopamine (DAT), but much less for norepinephrine transporters (NET), with selectivity for rat (r) or human (h) SERT over NET, but only 3′-iodo-substituted phenyltropanes showed selectivity for SERT versus DAT. The 3′-iodo, N-methyl analog of β-CIT (7) displayed 29-fold selectivity and high affinity for hSERT (Ki=9.6 nM) over hDAT (Ki=279 nM), and its nor-congener (8) showed even higher hSERT potency (Ki=1.2 nM) and selectivity over DAT (415-fold).