A mixture of 6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole (3.05 g, 13.8 mmol), 3-dimethylaminopropyl chloride hydrochloride (3.4 g, 21 mmol), K2CO3 (6.2 g, 45 mmol), tetrabutylammonium hydrogen sulfate (phase transfer catalyst, 1.5 g) in acetonitrile (100 ml) and water (50 ml) was heated at 60° C. overnight. The aqueous phase was separated, and acetonitrile was removed at reduced pressure. The residue was extracted into DCM. The organic solution was washed with H2O and brine, then dried with MgSO4. The solvent was removed and the crude product (4.3 g) was treated with fumaric acid (1.58 g, 1.0 eq) in dilute ethanol. The crystals were collected (2.53 g), m.p.=192°-194° C. Recrystallization from ethanol yielded 2.08 g of white crystals, mp=194°-195° C.
