Synthesis and pharmacological evaluation of 4,4-disubstituted piperidines.

A new class of piperidine derivatives is added to the increasing family of compounds related to fentanyl and carfentanil. Herein, we describe the synthesis and pharmacology of a number of 1-(arylethyl)-4-(acylamino)-4-[(acyloxy)-methyl]piperidines such as 9, 15, and 23. As expected, many of these congeners of fentanyl are extremely potent narcotic agonists. The aim of the study was to identify short-acting analgesic agents (i.e. less than 6 min in the mouse hot-plate assay) for possible use in the surgical theater. Many of the drugs proved to be of intermediate and long duration (i.e. 6-15 min and greater than 15 min, respectively). In addition to analgesic activity, many of the compounds exhibited anesthetic properties as well. The structure-activity relationship for these entities is presented and discussed.