(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.