To a solution of 1-[[2-(3,4,5-trimethoxyphenyl)pyridin-4-yl]methyl]-4-piperidone ethylene ketal (19.0 g) in THF (200 mL) was added 1 M hydrochloric acid (200 mL). The mixture was stirred at 90° C. overnight, then neutralized with 2 M sodium hydroxide and extracted with ethyl acetate. The organic layer was washed with brine, dried over anhydrous sodium sulfate and evaporated. The residual oil was applied to a column of silica gel using chloroform-methanol (40:1) as an eluent. Fractions containing the product were collected and evaporated to give the title compound.
