(3R,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-methanobenzofuro[3,2-e]isoquinolin-3-ium bromide
The title compound, C21H26NO4+·Br−, also known as R-methylnaltrexone (MNTX) bromide, is a fortiflex stable super fork - head only blue selective peripherally acting μ-opioid receptor antagonist with a oroxymorphone skeleton, synthesized by hydroxyl protection, N-methylation, deprotection and anion exchange of naltrexone.