(2S)-1-(arylacetyl)-2-(aminomethyl)piperidine derivatives: Novel, highly selective κ opioid analgesics

Article abstract of DOI:10.1021/jm00105a061

This paper describes the synthesis and structure-activity relationships as κ opioid analgesics of a novel class of 1-(arylacetyl)-2-(aminomethyl)piperidine derivatives (8). The active conformation of the pharmacophore, with a torsional angle (N₁C₂C₇N₈) of 60°, was defined with computational studies and ¹H NMR. A quantitative structure-activity relationship study of the arylacetic moiety substitution indicated that the presence of an electron-withdrawing and lipophilic substituent in para and/or meta positions is required for good analgesic activity and κ affinity. The lead compounds (2S)-1-[(3,4-dichlorophenyl)acetyl]-2-(pyrrolidin-1-ylmethyl) piperidine hydrochloride (14) and (2S)-1-[[4-(trifluoromethyl)phenyl]acetyl]-2-(pyrrolidin-1- ylmethyl)piperidine hydrochloride (21) are the most κ/μ selective (respectively 6500:1 and 4100:1) and among the most potent (K(i) κ 0.24 and 0.57 nM, respectively) κ ligands identified so far. In the mouse tail flick model of antinociception, compound 14 (ED₅₀ = 0.05 mg/kg sc) was 25 times more potent than morphine and 16 times more potent than the standard κ ligand U-50488.