Stereochemical studies of 3-aryl-3-methylpiperidines of potential opioid ligand activities by high-resolution 1H and 13C NMR spectroscopy

The 1H (270, 400 MHz) and 13C (22.5, 67.5 MHz) NMR spectra of a series of 2,3‐3,5‐ and 3,6‐dimethyl‐3‐(m‐hydroxy‐m‐methoxy‐phenyl)piperidines of proven or potential opioid ligand activity are reported. The data were analysed in terms of configuration and preferred conformation, and some key deductions were confirmed by NOED and 2D COSY experiments. In the 3,5‐dimethyl derivatives, isomers with preferred axial or equatorial 3‐aryl substituents were identified.