Methyl­naltrexone bromide methanol monosolvate

In the title compound [systematic name: (4R,4aS,7aR,12bS)-3-cyclo­propyl­meth­yl-4a,9-hy­droxy-7-oxo-2,3,4,4a,5,6,7,7a-octa­hydro-1H-4,12-methano­benzofuro[3,2-e]isoquinolin-3-ium bromide methanol monosolvate], C₂₁H₂₆NO₄⁺·Br⁻·CH₃OH, two of the three six-membered rings adopt chair conformations while the third, which contains a C=C double bond, adopts an approximate half-boat conformation. The 2,3-dihydro­furan ring adopts an envelope conformation. In the crystal, the components are linked by O—H...O and O—H...Br hydrogen bonds. The absolute stereochemistry was inferred from one of the starting materials.