Reaction Steps
Compound 81 (350 mg, 0.3 mmol) was dissolved in methanol (10 ml) by warming and then rapidly cooled. Methanolic sodium methoxide (0.2M, 0.2 ml) was added and the mixture was stirred at room temperature for 18 h, neutralized (Duolite C-26 (H+) resin), filtered and concentrated. The residue was dissolved in methanol (7 ml) and methanolic hydrazine hydrate (0.1M, 3 ml) was added. The mixture was refluxed for 33 h while two additional portions (2×3 ml) were added (after 24 and 30 h). The reaction was monitored by TLC (SiO2,chloroform methanol:water 65:35:10, lower phase). The solvent was removed and the residue was treated with a mixture of acetic anhydride (2.5 ml), ethanol (12 ml), and water (4 ml) at room temperature for 1 h. The ethanol was removed and the residue was partitioned between water (20 ml) and dichloromethane (5 ml). The aqueous phase was washed with dichloromethane (3×5 ml) and concentrated. The residue was chromatographed {Sephadex G-10 column. 3×57 cm, water) to give 82 (157 mg, 75%) with [α]D22 +34° (c 0.7, water). 1H-NMR [(CD3)2SO+D2O, 50°, Me4Si]δ inter alia 4.80 (d, 1H, J=3.5 Hz, H1"), 4.40 (d, 1H, J=8 Hz, H1 or H1'), 4.28 (d, 1H, J=7 Hz, H1or H1'), 4.08 (dt, 1H, J=6 and 1 Hz), 3.61 (s, CH3O), 2.75-2.70 and 2.61-2.54 (m, each 2H, SCH2CH2CO), 2.64 (t, 2H, J=7 Hz, OCH2CH2S), 1.80 (s, 3H, MeCON). 13C-NMR (D2O, TSP) δ 178.0, 177.3, 106.1, 103.8, 103.1, 81.6, 80.1, 78.2, 77.7, 75.3, 75.0, 73.7, 73.6, 72.1 (CH2), 72.0, 71.8, 71.4, 63.3 (CH2), 63.2 (CH2), 62.9 (CH2), 58.0 (C2), 55.2 (CH3O), 37.1 (CH 2), 33.8 (CH2), 29.4 (CH2), 23.2.
