C-alkylated spiro[benzofuran-3(2H),4'-1'-methyl-piperidine-7-ols] as potent opioids: a conformation-activity study

Bioorg Med Chem Lett. 1998 Jul 21;8(14):1813-8. doi: 10.1016/s0960-894x(98)00318-7.


Among a series of C-alkylated analogs of the weak mu opioid ligand spiro[benzofuran-3(2H),4'-1'-methylpiperidine-7-ol] (1), the 2-methyl, 2-ethyl, and cis 3'-methyl analogs, namely compounds (+/-)2, (+/-)-3, and (+/-)-4, showed much enhanced mu-affinities, with (+/-)-4 being almost as potent as (-)-morphine; while the trans 3'-methyl analog (+/-)-5 remained a weak mu-binder. Energy calculations and nmr data indicated that compounds 2-4 favor phenyl-axial conformations, while compounds 1 and 5 favor phenyl-equatorial conformations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Magnetic Resonance Spectroscopy
  • Molecular Structure
  • Piperidines / chemistry*
  • Piperidines / metabolism
  • Piperidines / pharmacology*
  • Protein Binding
  • Receptors, Opioid, mu / drug effects*
  • Receptors, Opioid, mu / metabolism
  • Structure-Activity Relationship


  • Piperidines
  • Receptors, Opioid, mu