[F:1][C:2]([F:15])([F:14])[S:3]([O:6]S(C(F)(F)F)(=O)=O)(=[O:5])=[O:4].O[C:17]1[CH:22]=[CH:21][C:20]([CH2:23][C:24]([O:26][CH3:27])=[O:25])=[CH:19][C:18]=1[CH3:28].C(N(CC)CC)C>C(Cl)Cl.O>[CH3:28][C:18]1[CH:19]=[C:20]([CH2:23][C:24]([O:26][CH3:27])=[O:25])[CH:21]=[CH:22][C:17]=1[O:6][S:3]([C:2]([F:15])([F:14])[F:1])(=[O:5])=[O:4]Trifluoromethane sulfonic anhydride (0.217 mL, 1.32 mmol) was added dropwise to methyl 2-(4-hydroxy-3-methylphenyl)acetate (159 mg, 0.88 mmol), in DCM (4 mL) at 0° C. under nitrogen. The resulting solution was then treated with triethylamine (0.369 mL, 2.65 mmol) and allowed to warm to and stir at 18° C. for 16 hours. The mixture was diluted with DCM (20 mL) and water (20 mL) and the organics separated. The organics were washed with saturated NaHCO3 (aq, 50 mL), brine (10 mL) dried (MgSO4) and evaporated to crude material. The crude product was purified by flash silica chromatography, elution gradient 0 to 30% EtOAc in isohexane. Pure fractions were evaporated to dryness to afford methyl 2-(3-methyl-4-(trifluoromethylsulfonyloxy)phenyl)acetate (169 mg, 61.3%) as a colourless oil.
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