Metazocine

Not to be confused with Metazosin.

Metazocine is an opioid analgesic related to pentazocine. While metazocine has significant analgesic effects,^[2] mediated through a mixed agonist–antagonist action^[3] at the mu opioid receptor,^[4] 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)^[5] and/or sigma receptors.^[6][7]

Metazocine

Clinical data
ATC code	none
Legal status
Legal status	BR: Class A1 (Narcotic drugs)[1] 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-methanobenzo[d]azocin-8-ol
CAS Number	3734-52-9 Y
PubChem CID	62518
ChemSpider	56292 Y
UNII	XD53YGT34W
KEGG	C11789
ChEMBL	ChEMBL257661 Y
CompTox Dashboard (EPA)	DTXSID20872483
ECHA InfoCard	100.020.998
Chemical and physical data
Formula	C15H21NO
Molar mass	231.339 g·mol−1
3D model (JSmol)	Interactive image
SMILES OC1=CC([C@@](C)([C@@]2([H])C)CCN(C)[C@]2([H])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 Y Key:YGSVZRIZCHZUHB-UHFFFAOYSA-N Y

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.^[8] 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 benzomorphan, metazocine (6), can be obtained from a variation of the morphinan synthesis.

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 gives the phenol. Although this last compound is in fact a relatively potent analgesic, it is not available commercially as a drug.^[9][10] Also see:^[11]

See also

• Phenazocine
• Pentazocine
• Cyclazocine