Hydrochloric Acid → 6-Fluoro-3-(4-piperidinyl)-1,2-benzisothiazole

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Reaction Steps

Reflux a solution of 4-(6-fluoro-1,2-benzisothiazol-3-yl)-1-piperidinecarboxaldehyde (Tetrahedron Lett., 1993, 34, 6525-6528, 12 g, 0.045 mol), 3N hydrochloric acid and ethanol (100 mL) for 3 hours. Stir at ambient temperature for 16 hours, add water and stir with ice bath chilling while adding sodium hydroxide solution until the mixture was basic. Extract with ethyl acetate, wash the extract with water, dry (MgSO4), filter and concentrate the filtrate to afford an oil which solidified on standing to afford 6-fluoro-3-(4-piperidinyl)-1,2-benzisothiazole (9.2 g). React 6-fluoro-3-(4-piperidinyl)-1,2-benzisothiazole under conditions as described for Example 11 to afford the title compound (0.25 g, 61% yield), LC/MS (APCI) m/e 510 (MH+), retention time 4.38 min.

Provenance & Evidence