Reaction Steps
Eight hundred mg of N-demethylnogalamycin is dissolved in a mixture of 10 ml of methanol and 2 ml of acetic anhydride. After the solution has stood at room temperature for 4 hours, it is evaporated to dryness under reduced pressure. The residue is chromatographed on 90 g of silica gel using chloroform-methanol (19:1) and collecting 201 five-ml fractions. Fractions 100-201 are combined and evaporated to dryness in vacuo to give 470 mg of N-acetyl-N-demethylnogalamycin; homogenous by TLC, Rf 0.38 in CHCl3 --CH3OH (9:1); [α]D +485°; (c 0.286, CHCl3); UV (EtOH) 236 nm (ε38,400), 258 nm (ε19,200), 290sh nm (ε12,800); IR (Nujol) 3380, 1715, 1705, 1650, 1615, 1585, 1285, 1215, 1135, 1100, 1045, 1025, 1000, 915, 875, 820, 750 cm-1 ; 1H NMR (CDCl3) δ1.1-1.7 (m, 12H), 2.10 (s, 3H), 3.20 (s, 3H), 3.25, 3.53, 3.62, 3.68 (4s, 12H), 2.8-4.62 (m), 5.22, 5.55, 5.88 (3 broad s, 3H), 7.26 (s, 1H), 7.52 (s, 1H), 13C NMR (CDCl3) δ191.1, 179.8, 174.7, 171.6, 161.6, 155.8, 146.9, 143.8, 136.5, 133.5, 130.4, 125.2, 116.1, 114.2, 113.9, 100.7, 95.92, 84.3, 81.0, 77.8, 75.7, 74.0, 71.5, 69.4, 67.3, 61.1, 59.2, 58.7, 56.8, 52.2, 48.5, 40.0, 32.2, 29.4, 23.6, 22.4, 18.0, 14.6; mass spectrum m/e 815.
