metazocine metazocine metazocine is an opioid analgesic related to pentazocine. while metazocine has significant analgesic effects, mediated through a mixed agonist–antagonist action at the mu opioid receptor, its clinical use is limited by dysphoric and hallucinogenic effects which are most likely caused by activity at kappa opioid receptors (where it is a high-efficacy agonist) and/or sigma receptors. not to be confused with metazosin. metazocineclinical dataatc codenonelegal statuslegal status ca: schedule i de: anlage i (authorized scientific use only) us: schedule ii identifiers iupac name (2r,6r,11r)-3,6,11-trimethyl-1,2,3,4,5,6-hexahydro-2,6-methanobenzoazocin-8-ol cas number3734-52-9 npubchem cid62518chemspider56292 yuniixd53ygt34wchemblchembl257661 ncomptox dashboard (epa)dtxsid20872483 echa infocard100.020.998 chemical and physical dataformulac15h21nomolar mass231.339 g·mol−13d model (jsmol)interactive image smiles oc1=cc((c)(2()c)ccn(c)2()c3)=c3c=c1 inchi inchi=1s/c15h21no/c1-10-14-8-11-4-5-12(17)9-13(11)15(10,2)6-7-16(14)3/h4-5,9-10,14,17h,6-8h2,1-3h3 ykey:ygsvzrizchzuhb-uhfffaoysa-n y ny (what is this?) (verify) metazocine is in schedule ii of the controlled substances act 1970 of the united states as a narcotic with acscn 9240 with a 19 gram aggregate manufacturing quota as of 2014. the free base conversion ratio for salts includes 0.81 for the hydrochloride and 0.74 for the hydrobromide. it is listed under the single convention for the control of narcotic substances 1961 and is controlled in most countries in the same fashion as is morphine. syntheses the prototype benzomorphan, metazocine (6), can be obtained from a variation of the morphinan synthesis. metazocine synthesis thus, reaction of the grignard reagent from p-methoxybenzyl chloride (1) with the lutidine methiodide (2) affords the benzylated dihydropyridine (3). reduction of the enamine π-bond leads to the tetrahydropyridine (4). cyclization by means of acid leads directly to the benzomorphan ring system (5). demethylation of the aromatic ring system affords the phenol. although this last compound is in fact a relatively potent analgesic, it is not available commercially as a drug.