Structure activity studies of a series of 4-(m-OH phenyl) piperidines

A series of 4-(m-OH phenyl)-piperidine analogs with R4 = methyl or t-butyl and NR = methyl, allyl and phenethyl have been synthesized; and their receptor affinities, in vivo analgetic agonism and antagonism, and energy-conformational profiles determined. These analogs bind selectively and with moderate to high affinity to opioid mu-receptors. Binding in their preferred phenyl axial conformation appears to lead to meperidine-like agonism. In addition, for some R4 = methyl but not t-butyl compounds, binding of an energy-accessible phenyl equatorial conformation produces antagonism.