Reaction Steps
To a stirred solution of 10 (0.546 g, 1.09 mmol) in CH2Cl2 (10 mL) cooled with ice bath (0° C.) was added Et3N (0.76 mL, 5.45 mmol), p-toluenesulfonyl chloride (TsCl, 0.416 g, 2.18 mmol) and catalytic amount 4-dimethylaminopyridine (DMAP, 0.11 mmol, 0.013 g). After maintaining at 0° C. for 15 min., the ice bath was removed, the reaction kept at r.t. overnight and then submitted to standard workup with CH2Cl2. The crude product was purified by FC (EtOAc/Hexanes, 40/60 to 50/50, V/V) to provide a pale white solid 11 (0.68 g, 96%). HPLC of 11: isomer one: 50%, Rt=12.53 min; isomer two: 50%, Rt=18.72 min; [column: Lux 3u Cellulose-1 (150×4.6 mm), UV detector, 210 nm, 5% 2-propanol in hexanes; flow rate: 1.0 mL/min]. 1HNMR (200 MHz, CD2Cl2) δ 7.72 (d, 2H, J=8.2 Hz), 7.28 (d, 2H, J=8.2 Hz), 6.79 (d, 1H, J=20.6 Hz), 6.15 (s, 2H), 5.14 (br s, 1H), 4.83 (t, 1H, J=6.8 Hz), 4.50-3.94 (m, 3H), 3.82 (s, 6H), 3.81 (s, 3H), 2.41 (s, 3H), 2.28-2.11 (m, 2H), 1.43 (s, 9H), 1.42 (s, 9H). 13C NMR (50 MHz, CD2Cl2) δ 171.0, 167.3, 161.8, 159.9, 155.8, 146.3, 133.3, 130.6, 128.5, 128.4, 106.6, 106.4, 91.3, 82.8, 82.5, 80.2, 78.0, 77.7, 56.4, 56.0, 35.7, 35.3, 32.9, 28.7, 28.3, 22.0. HRMS calcd for C31H45N2O11S (M+H)4: 653.2744. found: 653.2734, 653.2739.
