Bromine (0.67 ml, 13 mmol) was added dropwise to a solution of 4′-(trifluoromethyl)acetophenone (2.5 g, 13 mmol) in diethylether (20 ml) and 1,4-dioxane (10 ml) at room temperature. Chlorzoxazone (2.19 g, 13 mmol) was treated with sodium hydride (400 mg, 13 mmol) in DMF for 15 min. under N2 and transferred by cannulation into the freshly prepared solution of bromide. The reaction mixture was stirred at 60° C. for 3 h, and poured into water (1 vol). The product was extracted with ethyl acetate, and the organic layer washed with water and brine and dried. Concentration gave a solid 4.4 g (93%) which was recrystallized from acetonitrile. mp 188-189° C.; IR(KBr, υ=cm−1) 1776, 1704, 1330, 1226, 1122; 1H NMR (300 MHz, DMSO-d6) δ 5.64 (2H, s), 7.20 (1H, dd, J=8.6 Hz, 2.1 Hz), 7.44 (1H, d, J=8.5 Hz), 7.57 (1H, d, J=2.1 Hz), 7.99 (2H, d, J=8.3 Hz), 8.27 (2H, d, J=8.1 Hz); MS(DCl)m/Z: 356 (MH+) Anal. calcd. for C16H9ClF3NO3: C, 54.03; H, 2.55; N, 3.94. Found: C, 53.73; H, 2,43; N, 3.88.
