To a mixture of tert-butyl 4-(1,4-dioxaspiro[4.5]decan-8-yloxy)-5-cyclopropyl-2-fluorobenzoate (0.557 g, 1.44 mmol) in tetrahydrofuran (1.5 mL) and water (1.5 mL) was added trifluoroacetic acid (0.5 mL) and the reaction mixture was stirred for 16 hours at ambient temperature. After addition of dichloromethane (100 mL), the mixture was washed with saturated sodium bicarbonate solution (10 mL), brine (10 mL), and dried over anhydrous sodium sulfate. Filtration and concentration of the filtrate in vacuo gave a residue which was purified by silica gel column chromatography using 0-30% ethyl acetate in hexanes as eluent to afford the title compound as a colorless oil (0.300 g, 60%): 1H NMR (300 MHz, CDCl3) δ 7.42 (d, J=8.4 Hz, 1H), 6.59 (d, J=12.6 Hz, 1H), 4.80-4.71 (m, 1H), 2.77-2.62 (m, 2H), 2.42-2.27 (m, 4H), 2.14-1.93 (m, 3H), 1.56 (s, 9H), 0.94-0.84 (m, 2H), 0.65-0.60 (m, 2H).
