Synthesis and structure–activity relationships of a new series of 2α-substituted trans-4,5-dimethyl-4-(3-hydroxyphenyl)piperidine as μ-selective opioid antagonists

Structure–activity relationships at the 2α-position of the piperidine ring of the trans-4,5-dimethyl-4-(3-hydroxyphenyl)piperidine μ-opioid antagonist series were investigated. This study showed that only small linear alkyl groups (methyl, propyl) are tolerated at the 2α-position of the piperidine ring of this series.