(3S,4R,4aS,7aR,12bS)-3-Cyclo­propyl­meth­yl-4a,9-dihy­droxy-3-methyl-7-oxo-2,3,4,4a,5,6,7,7a-octa­hydro-1H-4,12-methano-1-benzofuro[3,2-e]isoquinolin-3-ium 2,2,2-trifluoro­acetate methanol solvate

In the title compound, C(21)H(26)F(3)NO(6) (+)·CF(3)COO(−)·CH(3)OH or S-MNTX·CF(3)COO(−)·CH(3)OH (MNTX = methyl­naltrexone), the conformation of the polycyclic backbone of the noroxy­morphone skeleton can be simplified in terms of the angles between the least-squares planes of these rings. The dihedral angle between the cyclohexene and piperidine rings is 84.5 (6)°, while the dihedral angles between the planes of cyclohexane ring and the benzene, cyclohexene and piperidine rings, respectively, are 85.8 (6),80.0 (7) and 10.3 (7)°. In the crystal, mol­ecules are linked by O—H⋯O hydrogen bonds. The trifluoro­acetate F atoms are disordered in a 0.710 (14):0.710 (14) ratio. The absolute stereochemistry was inferred from the use of (4R,4aS,7aR,12bS)-3-(cyclo­propyl­meth­yl)-4a,9-dihy­droxy-2,3,4,4a,5,6-hexa­hydro-1H-4,12-meth­ano­benzofuro[3,2-e]isoquinolin-7(7aH)-one as one of the starting materials.