Disclosed herein is a method of preparing solifenacin or a salt thereof, including the steps of: (a) reacting (R)-quinuclidinol with bis(pentafluorophenyl)carbonate in an organic solvent to prepare a solifenacin intermediate, (3R)-1-azabicyclo[2,2,2]oct-3-yl pentafluorophenylcarbonate, and (b) reacting the solifenacin intermediate with (1S)-1-phenyl-1,2,3,4-tetrahydroisoquinoline in an organic solvent to prepare solifenacin. The method is advantageous in that high-purity solifenacin or a salt thereof can be simply and efficiently prepared with high yield using a novel intermediate.
