To a mixture of 1,4-dioxaspiro[4.5]decan-8-ylmethanol (5.00 g, 29.0 mmol) and tert-butyl 5-chloro-2,4-difluorobenzoate (7.22 g, 29.00 mmol) in anhydrous dimethyl sulfoxide (30 mL) was added cesium carbonate (18.90 g, 58.00 mmol) and the reaction mixture was heated at 70-80° C. for 4 hours. After cooling to ambient temperature, ethyl acetate was added (200 mL) and the mixture was washed with water (4×15 mL), brine (2×15 mL); dried over anhydrous sodium sulfate, and filtered. After concentration of the filtrate in vacuo, the residue 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 (5.06 g, 44%): 1H NMR (300 MHz, CDCl3) 7.85 (d, J=7.7 Hz, 1H), 6.60 (d, J=12.2 Hz, 1H), 3.95-3.93 (m, 4H), 3.83 (d, J=6.3 Hz, 2H), 1.98-1.87 (m, 4H), 1.84-1.71 (m, 4H), 1.64-1.56 (m, 1H), 1.56 (s, 9H).
