Assessment of the chloroethyl analog of 3-PPP (N-n-propyl-3-(3-hydroxyphenyl)-piperidine), 3-PPP-C1 as an irreversible ligand for central dopaminergic recognition sites

NCA, the chloro analog of the potent dopamine agonist NPA is an irreversible ligand at dopamine receptors in mammalian brain. The chloroethyl analog of the recently described putative dopamine autoreceptor agonist 3-PPP, 3-PPP-C1, was evaluated for its potential use as an irreversible autoreceptor ligand. N-Chloroethylation of 3-PPP reduced the intrinsic affinity of the agonist seven-fold and, consequently, in contrast to NCA, it was found that 3-PPP-C1 was not a good irreversible ligand at dopamine receptors.