1,4-Dioxaspiro(4.5)decan-8-ol → 4-(1,4-Dioxaspiro[4.5]decan-8-yloxy)-5-chloro-2-fluorobenzoic acid

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Reaction Steps

To a solution of 1,4-dioxaspiro[4.5]decan-8-ol (12.90 g, 81.50 mmol) in dimethylsulfoxide (800 mL) was added potassium tert-butoxide (21.00 g, 187.00 mmol). The reaction mixture was stirred at ambient temperature for 15 minutes under nitrogen. To this mixture was added 5-chloro-2,4-difluorobenzoic acid (15.70 g, 81.70 mmol). The mixture was stirred at ambient temperature for 3 days, after which it was split into two equal portions. Each portion was diluted with ethyl acetate (700 mL), washed with 1 M hydrochloric acid (700 mL), a 1:1 mixture of 1 M hydrochloric acid and brine (700 mL), and brine (700 mL). The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated in vacuo to dryness. The residue was purified by column chromatography with a gradient of a solution of 0.2% acetic acid in ethyl acetate and hexanes from 0-50%, to afford the title compound as a light yellow solid (5.66 g, 21%): 1H NMR (300 MHz, CDCl3) δ 9.24 (br s, 1H), 8.01 (d, J=7.7 Hz, 1H), 6.69 (d, J=12.4 Hz, 1H), 4.54-4.51 (m, 1H), 3.97-3.95 (m, 4H), 2.06-1.93 (m, 4H), 1.81-1.74 (m, 1H), 1.70-1.51 (m, 3H); MS (ES−) m/z 329.1, 331.1 (M−1).

Provenance & Evidence