Water → 4-(6-Fluoro-1,2-benzisoxazol-yl)-1-[3-(1-piperidinyl)propyl]piperidine difumarate

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Reaction Steps

A mixture of 4-(6-fluoro-1,2-benzisoxazol-3-yl)piperidine (3.0 g, 13.6 mmol), N-(3-chloropropyl)piperidine hydrochloride (4.05 g, 20.4 mmol), K2CO3 (6 g, 43.4 mmol), tetrabutylammonium hydrogen sulfate (phase transfer catalyst, 2.3 g) in acetonitrile (100 ml) and water (15 ml) was heated at reflux for 16 hours. The mixture was washed with brine and the layers were separated. The organic solution was concentrated. The crude product (6.4 g) was purified by flash chromatography over a silica gel column (55 g, sorbsil C-30; eluted with 2% CH3OH:0.5% DEA in DCM, 1.41). The oil thus purified (4.5 g) was treated with fumaric acid (1.6 g) in ethanol. The solid was collected: weight 3.1 g, m.p.178-181° C. Recrystallization from ethanol yielded 2.28 g of white crystals, m.p.=190-192° C.

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