Reaction Steps
Method B (from 16): Following the procedure described for the preparation of 6, treatment of 16 (40.0 mg, 0.0705 mmol, 1.0 equiv) with FeCl36.H2O (66.3 mg, 4.0 equiv) resulted in the desired product. Purification was done by flash column chromatography (silica gel, 3% acetone in CH2Cl2). Yield: 25.2 mg, 55%. 1H NMR (400 MHz, CDCl3) δ: 9.18 (s, 1H, 10-H), 9.03 (d, J=14 Hz, 1H, 5-H), 8.65 (s, 1H, 20-H), 5.79-5.86 (m, 1H, 31-H), 5.48 (d, 2H, 132-H), 4.41-4.50 (m, 1H, 8-H), 4.20-4.22 (m, 1H, 7-H), 3.90 (t, J=8.0 Hz, 2H, 17-CH2), 3.75 (s, 3H, COOCH3), 3.52-3.66 (m, 5H, 31-OCH2+12-CH3), 3.43 (d, J=3.6 Hz, 3H, 2-CH3), 3.23 (s, 3H, 18-CH3), 2.94 (t, J=8.0 Hz, 2H, 171-CH2), 2.42-2.52 (m, 1H, 81-H), 2.13-2.20 (m, 1H, 81-H), 2.10 (d, J=6.8 Hz, 3H, 31-CH3), 1.91/1.87 (d, J=7.2 Hz, 3H, 7-CH3), 1.66-1.76 (m, 3H, 31-OCH2CH2CH2CH2CH2CH3), 1.15-1.23 (m, 9H, 31-OCH2CH2CH2CH2CH2CH3+81-CH3), 0.78-0.81 (m, 3H, 31-OCH2CH2CH2CH2CH2CH3), −0.34 (br s, 1H, NH), −1.52 (br s, 1H, NH). MS (ESI) m/z: 651.4 (M++1). UV-vis, CH2Cl2, λmax nm (ε): 669 (4.45×104), 612 (6.77×103), 540 (6.77×103), 513 (1.11×104), 411 (7.82×104).
