Reaction Steps
Compound 80 (1.46 g, 1.1 mmol) was dissolved in a mixure of methanol (75 ml) and tetrahydrofuran (10 ml) by warming. The clear solution was rapidly cooled to ~40° C. and methanolic sodium methoxide (0.2 M, 5 ml) was added. The mixture was stirred at room temperature for 5 h, after which time the deacetylation was complete. (TLC; SiO2,chloroform:methanol:water 65:35:10, lower phase), neutralized by addition of acidic ion-exchange resin (Duolite C-26), filtered and evaporated. The residue was re-dissolved in refluxing methanol (50 ml) and hydrazine hydrate (0.5 g, 10 mmol) was added. The reflux was continued for 17.5 h, whereafter the solvent was evaporated. The residue was acetylated by stirring for 22 h at room temperature in a mixture of pyridine and acetic anhydride (1:1, 50 ml). After evaporation, the residue was subjected to chromatography (SiO2 -column, 5×18 cm, ethyl acetate: isooctane gradient: 2:1-4:1-ethyl acetate) which gave amorphous 83 (0.72 g, 52%) with [α]D21 +32° (c 1.1, chloroform). 1H-NMR (CDC13, Me4Si) δ 5.67 (d, 1H, J=9.5 Hz, NH), 5.58 (bd, 1H, J=3 Hz, H4"), 5.39 (dd, 1H, J=11 and 3 Hz, H3"), 5.23-5.01 (3H, H2', H2" and H3), 4.99 (d, 1H, J=3.5, H1"), 4.75 (dd, 1H, J=11 and 2.5 Hz, H3') 4.58-4.37 (5H, inter alia H1and H1'), 4.54 and 4.49 (2d, each 1H, J=8 Hz each, H1 and H1'), 4.23-3.90 (7H), 3.85-3.55 (4H), 2.69 (t, 2H, J=7 Hz, OCH2CH2S), 2.51 (t, 2H, J=7 Hz, SCH2), 2.13, 2.12, 2.11, 2.08 (4s, each 3H, MeCO), 2.075, 2.05 (2s, each 6H, MeCO), 1.99, 1.97 (2s, each 3H, MeCO), 1.66-1.20, 0.88 (t, 3H, J=6.5 Hz, CH3CH2). 13C-NMR (CDC13, Me4Si) δ 170.6 (2C), 170.4 (3C), 170.2, 170.1, 169.6, 169.0, 101.1, 101.0 (d, J each 160 Hz, C1 and C1'), 99.6 (d, J=172 Hz, C1"), 76.9, 75.9, 72.7, 72.6 (2C), 71.8, 69.1 (OCH2CH2), 68.9, 68.7, 67.8, 67.1, 67.0, 62.4 (CH2), 61.3 (CH2), 60.2 (CH2), 53.3 (C2), 32.5-28.8, 23.3 (CH3CONH), 22.7 (CH2), 20.9-20.5, 14.1.
