Reaction Steps
(±)-2,3-Dihydroxypropyl tosylate (IV) (525 mg, 2.13 mmol, 1 eq.) was dissolved in pyridine (20 mL, anhydrous) and cooled to 0° C. 4,4′-Dimethoxytrityl chloride (758 mg, 2.24 mmol, 1.05 eq.) was added in 3 portions over 2 h and the reaction solution was allowed to warm up to rt. After 2 h, sat. aq. NaHCO3 (75 mL) was added to the reaction mixture, followed by extraction with CH2Cl2 (3×75 mL). The extract was dried with Na2SO4, filtered, concentrated in vacuo and dried by coevaporation with toluene (3×). Purification by flash column chromatography (SiO2, 1:2:97 NEt3/Et2O/CH2Cl2) gave V as a white powder (770.6 mg, 66%). 1H NMR (300 MHz, CD2Cl2/D2O): δ=7.74 (d, J=8.4 Hz, 2H, arom.), 7.36-7.21 (m, 11H, arom.), 6.82 (d, J=5.1 Hz, 4H, arom.), 4.10-3.98 (m, 2H, CH2OTs), 3.92-3.89 (m, 1H, CHOH), 3.78 (s, 6H, OCH3), 3.13-3.11 (m, 2H, CH2ODMT), 2.44 (s, 3H, C6H4CH3); 13C{1H} NMR (75.5 MHz, CD2Cl2/D2O): δ=159.3, 145.8, 145.3, 136.1, 133.1, 130.6, 129.6, 128.44, 128.41, 127.5, 127.4, 113.7, 86.9, 71.8, 69.3, 64.1, 55.8, 22.0; MS (EI): m/z. calcd for [C31H32O7S]+: 548.1869. found: 548.1867 [M]+. elemental analysis calcd (%) for C31H32O7S: C, 67.86; H, 5.88; found: C, 67.84; H, 5.93.
