General procedure for the synthesis of 1-(2-hydroxy-4-(trifluoromethyl)phenyl)ethanone from (E)-1-ethoxy-3-trifluoromethyl-1,3-butadiene and acetylacetone: at 0 °C, 4-ethoxy-1,1,1-trifluoro-3-buten-2-one (5 g, 29.7 mmol) and 2,4-pentanedione (3.05 mL, 29.7 mmol) were were added sequentially to a suspension of THF (120 mL) containing NaH (2.38 g, 59.4 mmol). The reaction mixture was refluxed for 4 h and subsequently partitioned with 1N HCl and EtOAc. The organic layer was washed with brine, dried over Na2SO4 and concentrated to give a red oil. Purification by fast column chromatography (eluent: hexane solution with 0 to 10% EtOAc) afforded 1-(2-hydroxy-4-(trifluoromethyl)phenyl)ethanone as a yellow oil (1.73 g, 29% yield).1H NMR (400 MHz, CDCl3): δ 2.69 (s, 3H), 7.15 (d, J = 9.9 Hz, 1H). 7.25 (s, 1H), 7.86 (d, J = 8.3 Hz, 1H), 12.29 (s, 1H).
