N-[(4aR,7aR)-6-[5-Fluoro-4-(1-hydroxy-1-methyl-ethyl)-6-methyl-pyrimidin-2-yl]-7a-isothiazol-5-yl-4,4a,5,7-tetrahydropyrrolo[3,4-d][1,3]thiazin-2-yl]benzamide (33 mg, 0.064 mmol) is dissolved in ethanol (2 mL). To this solution is added pyridine (0.052 mL, 0.6 mmol) and O-methylhydroxylamine hydrochloride (55 mg, 0.6 mmol). The reaction is warmed to 70° C. for 4 hours. The reaction is cooled to room temperature and stirred overnight (˜16 hrs). The mixture is concentrated to give the crude product which is purified via silica gel chromatography using a 0-10% (7 N NH3 in MeOH)/DCM to give the pure freebase. The freebase is dissolved in DCM (2 mL) and treated with 4 M HCl in dioxane (0.3 mL, 1.2 mmol). The mixture is concentrated to give the title compound as a white solid (18 mg, 0.04 mmol). ES/MS (m/z): 409 (M+H). [α]D20=−6.0° (C=1.0, MeOH).
