To a solution of 2-(4-fluorophenyl)-8-methyl-3-(2-methylsulfanylpyrimidin-4-yl)-imidazo[1,2-a]pyrazine (Example #F.1A; 8.58 g, 24.4 mmol) in MeOH (200 mL) and DCM (200 mL) at ambient temperature was added Oxone® (30.0 g, 48.8 mmol) in water (100 mL) to form a suspension. After about 20 h of stirring the layers were separated. The aqueous layer was washed with DCM (3×30 mL). Combined organic layers were washed with brine, dried over MgSO4, and concentrated under reduced pressure to yield a yellow solid, which was purified via FCC using EtOAc as an eluent. The product-containing fractions were combined and concentrated under reduced pressure to give a white solid (6.5 g) that was recrystallized in IPA (700 mL) to yield the title compound (3.6 g) after filtration. Additional product was observed in the filtrate. (3.6 g, 38% yield): LC/MS (Table 1, Method b) Rt=1.7 min; MS m/z: 384.1 (M+H)+.
