Ethyl Acetate → 4-[4-(6-Fluoro-1,2-benzisoxazol-3-yl)-1-piperidinyl]2-methyl-2-hydroxybutane fumarate

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Reaction Steps

To a solution of ethyl 3-[4-(6-fluoro-1,2-benzisoxazol-3-yl)-1-piperidinyl]propionate (3.21 g, 10 mmol) in tetrahydrofuran (THF, 100 ml), was added methylmagnesium bromide (10 ml, 30 mmol, 3M solution in ether) dropwise over 15 minutes at room temperature under N2. The resulting mixture was stirred for 16 hours. The mixture was slowly hydrolyzed with aqueous NH4Cl solution. The THF solution was diluted with EtOAc (300 ml), then was washed with water and brine. The organic solution was separated and dried over MgSO4. After removal of solvent, the crude product was purified by flash chromatography (25 g, SiO2 ; eluted with 1 CH3OH:99 DCM). The material thus purified weighed 2.36 g (77%) as white crystals. This was converted to the fumarate salt by treatment with fumaric acid (895 mg) in ethanol. Recrystallization from ethanol yielded white crystals, 2.47 g, m.p.=156°-158° C.

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