(rac)-1,1,1-Trifluoro-2-propanol (Oakwood) (189.30 g, 1.66 mole) in N,N-dimethylacetamide (200 mL) was added to a stirred, ice-bath cooled mixture of hexanes washed sodium hydride (60% dispersion in mineral oil) (Aldrich) (66.40 g, 1.66 mole) and N,N-dimethylacetamide (1900 mL) under nitrogen. The reaction was stirred at ambient temperature (5-20° C.) for 0.5 hour. 3-Fluorophenoxathiin 10,10-dioxide (Example 47) (277.78 g, 1.11 mole) in N,N-dimethylacetamide (1800 mL) was added at a bath temperature of 5-15° C. and stirred at ambient temperature for 1 hour. The reaction mixture was poured into water (8 L) and extracted with ethyl acetate (3 L, 2 L). The combined extracts were washed with water (4 L, 2 L), brine (0.5 L), dried over magnesium sulfate and filter. The volatiles were removed by spin evaporation in vacuo. The residue was stirred with hexanes (1 L) and collected by suction filtration to give 399.51 g of crude product. Recrystallization from 2-propanol (1.5 L) gave 304.62 g (79% yield) of (rac)-3-(2,2,2-trifluoro-1-methylethoxy)phenoxathiin 10,10-dioxide, m.p. 98-100 C.
