3-PPP (N-n-propyl-3-(3-hydroxyphenyl)piperidine) is a mixed sigma σ1 and σ2 receptor agonist (with similar affinity for both subtypes, though slightly higher affinity for the latter)[1] and D2 receptor partial agonist which is used in scientific research.[2] [3] It shows stereoselectivity in its pharmacodynamics. (+)-3-PPP is the enantiomer that acts as an agonist of the sigma receptors; it is also an agonist of both D2 presynaptic and postsynaptic receptors. Conversely, (−)-3-PPP, also known as preclamol, acts as an agonist of presynaptic D2 receptors but as an antagonist of postsynaptic D2 receptors, and has antipsychotic effects.[4] 3-PPP has also been reported to be a monoamine reuptake inhibitor and possibly to act at adrenergic receptors or some other non-sigma receptor.[5]
The Grignard reagent was prepared for 3-Bromoanisole [2398-37-0] (1) and this was reacted with 3-Bromopyridine [626-55-1] (2) to give 3-(3-methoxyphenyl)pyridine [4373-67-5] (3). Reaction with 1-bromopropane [106-94-5] occurred to give the quaternary salt PC13695099 (4a). Catalytic hydrogenation of the quat cation gave 3-(3-methoxyphenyl)-1-propylpiperidine [86562-23-4] (5). Demethylation with hydrogen bromide then completed the synthesis of preclamol (6).