To a 1L reaction flask equipped with a mechanical stirrer and a nitrogen inlet was added 4-isopropylamino-1-(4-methoxypyrid-3-ylmethyl)piperidine (45.7 g, 0.174 mol) and 200 mL of MTBE. The resulting mixture was heated to 50-55° C. to dissolve the solid. To this solution was added a solution of benzoic acid (21.3 g, 0.174 mol) in 100 mL of MTBE at 50-55° C. (Note: Heat may be needed to dissolve the benzoic acid in MTBE). This mixture was stirred at 50-55° C. for 30 minutes and then stirred at room temperature for 16 hours. The resulting solid was filtered and washed with 50 mL of MTBE and then dried under vacuum at 40° C. for 16 hours to give 54.9 g of the title intermediate as a white solid (82% yield; ≧99% purity).
