Reaction Steps
To a vigorously stirring solution of 12 (1120 mg, 4.42 mmol) in CH2Cl/MeOH (9:1, 1000 mL) was added the protected dithiol 8A (430 mg, 0.44 mmol) in CH2Cl2/MeOH (9:1, 500 mL) dropwise over 30 minutes. After stirring for a further 30 minutes, 0.1M sodium thiosulfate (300 mL) and sat. NaCl (100 mL) were added, extracting with CH2Cl2 (3×100 mL). The combined organic extract was dried (MgSO4), filtered, and solvent removed. The residue was purified by flash chromatography (eluent 1-6% MeOH/CH2Cl2) to give 9A (205 mg, 0.42 mmol, 96%) as a white solid: [α]22D −98.0 (c 0.50, CHCl3); IR νmax 3300, 2477, 1734, 1659, 1526, 1446 cm−1; 1H NMR (400 MHz, CDCl3) δ 7.46 (d, J=6.5 Hz, 1H), 7.33 (t, J=5.3 Hz, 1H), 7.28 (d, J=8.8 Hz, 1H), 6.60 (d, J=3.8 Hz, 1H), 5.95 (dtd, J=16.1, 6.5, 2.0 Hz, 1H), 5.80-5.70 (m, 2H), 4.85 (ddd, J=9.8, 8.5, 3.8 Hz, 1H), 4.21 (qd, J=7.3, 3.8 Hz, 1H), 4.11 (d, J=5.3 Hz, 2H), 3.44 (dd, J=15.6, 10.0 Hz, 1H), 3.20 (dd, J=10.3, 6.8 Hz, 1H), 3.01-2.95 (m, 2H), 2.92 (dd, J=15.6, 4.0 Hz, 1H), 2.85-2.58 (m, 5H) 1.49 (d, J=7.5 Hz, 3H), 0.98 (d, J=6.5 Hz, 3H), 0.92 (d, J=6.5 Hz, 3H); 13C NMR 100 MHz 173.3 (C), 171.6 (C), 171.0 (C), 169.4 (C), 168.2 (C), 130.4 (CH), 130.3 (CH), 69.8 (CH), 64.9 (CH), 54.5 (CH), 52.0 (CH), 42.4 (2×CH2), 38.7 (CH2), 38.6 (CH2), 32.7 (CH2), 27.5 (CH), 20.8 (CH3), 20.1 (CH3), 16.7 (CH3); LRMS (ES+) m/z 995 (50%, [2M+Na]+), 509 (80%, [M+Na]+), 487 (100%, [M+H]+); HRMS m/z 509.1495 (M+Na)+ expected 509.1499.
