[Br:1][C:2]1[CH:3]=[CH:4][C:5]([F:13])=[C:6]([CH:8]([OH:12])[C:9]([CH3:11])=[CH2:10])[CH:7]=1.C1COCC1.CC([O-])=O.[Na+].C([O-])([O-])=O.[K+].[K+]>O>[Br:1][C:2]1[CH:3]=[CH:4][C:5]([F:13])=[C:6]([CH:8]([OH:12])[CH:9]([CH3:10])[CH3:11])[CH:7]=1A flask was charged with 1-(5-bromo-2-fluorophenyl)-2-methylprop-2-en-1-ol (5.39 g, 22 mmol), THF (120 mL), and water (120 mL). With vigorous stirring, p-toluenesulfonylhydrazide (20.5 g, 110 mmol) and NaOAc (18.05 g, 220 mmol) were added successively. The mixture was then refluxed at 70° C. for 20 hours. After cooling to room temperature, saturated K2CO3 solution was added, and the mixture stirred for 5 minutes. The aqueous layer was then extracted with Et2O, dried over MgSO4, and purified by column chromatography (gradient 0 to 15% EtOAc in hexanes) to give the product. 1H NMR (400 MHz, CDCl3) δ 7.58 (dd, J=6.3, 2.6 Hz, 1H), 7.34 (ddd, J=8.5, 4.5, 2.6 Hz, 1H), 6.94-6.86 (m, 1H), 4.71 (d, J=6.6 Hz, 1H), 1.97 (dq, J=13.5, 6.7 Hz, 1H), 1.84 (br s, 1H), 0.98 (d, J=6.7 Hz, 3H), 0.88 (d, J=6.8 Hz, 3H).
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