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0 °C

To a cooled (0° C), stirred solution of 990 mg (2.30 mmol) 3-[3-(5-bromo-2-methoxyphenylsulfonyloxy)-5-methylphenoxy]propanol, as prepared in the preceding step, 842 μL of N,N-diisopropylethylamine and 500 μL of anhydrous dimethyl sulfoxide in 6.0 mL of anhydrous dichloromethane was added 732 mg (4.60 mmol) of sulfur trioxide pyridine complex. The mixture was warmed to ambient temperature over 30 min and stirred for 2 h. An additional 368 mg (2.30 mmol) of sulfur trioxide pyridine complex was added and, after 17 h, the mixture was poured into 15 mL of dichloromethane and washed with 5% (w/v) aqueous citric acid (2×25 mL). Each wash was extracted with 5 mL of dichloromethane and the combined extracts were washed with 1M pH 7 buffer (25 mL), brine (25 mL) and dried over Na2SO4 to give after concentration a white semisolid. This material was chromatographed on 35 g of silica gel with dichloromethane followed by 3% ethyl acetate-dichloromethane to afford 685 mg (69%) of the title compound as a colorless syrup: 1H-NMR (300 MHz; CDCl3) δ 9.84 (t, 1 H, J=1.4 Hz), 7.94 (d, 1 H, J=2.5 Hz), 7.70 (dd, 1 H, J=8.9, 2.5 Hz), 6.98 (d, 1 H, J=8.9 Hz), 6.61 (br s, 1 H), 6.55 (br s, 1 H), 6.45 (t, 1 H, J=2.2 Hz), 4.21 (t, 2 H, J=6.1 Hz), 4.01 (s, 3 H), 2.88 (td, 2 H, J=6.1, 1.4 Hz) and 2.27 (s, 3 H). Mass spectrum (MALDI-TOF, gentisic acid matrix) calcd. for C17H1779BrO6S: 451.0 (M+Na). Found: 451.4.

1. additionwas added 732 mg (4.60 mmol) of sulfur trioxide pyridine complex
2. temperatureThe mixture was warmed to ambient temperature over 30 min
3. additionAn additional 368 mg (2.30 mmol) of sulfur trioxide pyridine complex was added and, after 17 h
4. washwashed with 5% (w/v) aqueous citric acid (2×25 mL)
5. extractionEach wash was extracted with 5 mL of dichloromethane
6. washthe combined extracts were washed with 1M pH 7 buffer (25 mL), brine (25 mL)
7. dry with materialdried over Na2SO4
8. customto give
9. concentrationafter concentration a white semisolid
10. customThis material was chromatographed on 35 g of silica gel with dichloromethane