To a mixture of adamantan-1-ylmethanol (1.00 g, 6.0 mmol) in anhydrous dimethyl sulfoxide (40 mL) was added potassium t-butoxide (1.68 g, 15.0 mmol) at room temperature. The resulting mixture was stirred at room temperature for 30 min followed by the addition of 5-chloro-2,4-difluoro-N-(methylsulfonyl)benzamide (1.62 g, 6.0 mmol). The reaction mixture was stirred at room temperature for 16 h. The mixture was cooled to 0° C. and quenched with hydrochloride acid (1N, 30 mL) followed by extraction with ethyl acetate (200 mL). The organic layer was washed with water (2×40 mL), dried over anhydrous sodium sulfate, and filtered. The filtrate was concentrated in vacuo, the crude product was purified by silica gel column chromatography using 10-60% ethyl acetate (containing 0.2% acetic acid) in hexanes as an eluent to afford the title compound as a white solid (1.17 g, 46%): 1H NMR (300 MHz, DMSO-d6) δ 12.10 (s, 1H), 7.77 (d, J=7.5 Hz 1H), 7.23 (d, J=12.5 Hz, 1H), 3.72 (s, 2H), 3.35 (s, 3H), 1.99 (br s, 3H), 1.75-1.64 (m, 12H); 13C NMR (75 MHz, DMSO-d6) δ 162.3 (d, J=2.2 Hz), 159.8 (d, JC-F=255 Hz), 158.3 (d, JC-F=11 Hz), 130.6 (d, JC-F=4 Hz), 116.8 (d, JC-F=3 Hz), 113.6 (d, JC-F=14 Hz), 102.7 (d, JC-F=28 Hz), 79.1, 41.2, 38.5, 36.4, 33.4, 27.3; MS (ES−) m/z 414.1, 416.1 (M−1).
