(1R,2R)-1-[(3,4-dimethoxyphenyl)methyl]-1,2,3,4-tetrahydro-6,7-dimethoxy-2-(3-methoxy-3-oxopropyl)-2-methylisoquinolium Benzenesulfonate is one of the reactants used in process for preparation of cisatracurium compounds, which are therapeutically useful as nondepolarizing neuromuscular blocking agents.