To a solution of methyl 4-(3-amino-6-(1,4-dioxaspiro[4.5]decan-8-yl)pyrazin-2-yl)-2-fluorobenzoate (6.2 g, 16.00 mmol) in Acetonitrile (100 mL), Water (40 mL), was added 3M aqueous solution HCl (13.34 mL, 80 mmol). The reaction was stirred at room temperature for 30 min. The reaction mixture was basified with 6M NaOH (10 mL), then use sat. NaHCO3 to adjust to pH 8. After acetonitrile was removed in vacuo, the solid suspension residue was filtered and washed with water and heptane, air-dried to give methyl 4-(3-amino-6-(4-oxocyclohexyl)pyrazin-2-yl)-2-fluorobenzoate as light yellow solid in 67% yield. LCMS (m/z): 344.0 (MH+), 0.70 min.
