Trifluoromethanesulfonic anhydride (0.12 ml) was added to 7-[2-(2-chloro-4-hydroxy-phenyl)-1-hydroxy-1-trifluoromethyl-propyl]-4-methyl-4H-benzo[1,4]oxazin-3-one (150 mg, Example 158 step 2) and triethylamine (0.2 ml) in DCM (5 ml). The mixture was stirred for 2 h at room temperature. 10% aqueous citric acid was added and extracted with DCM. The combined organic layers were dried over Na2SO4 and then concentrated to give the title compound (140 mg) as light yellow foam. MS (m/e, ISP neg. ion)=546.2 [M−H+].
