Reaktionsschritte
A mixture of 42 (0.48 g, 1.0 mmol) and KOAc (0.49 g, 5.0 mmol) in MeOH/H2O (20 ml/2 mL) was stirred at room temperature for 24 h. AcOH (0.286 mL 5.0 mmol) was added and stirring was continued at room temperature for 15 min. The reaction mixture was evaporated and the residue was partitioned between H2O/CHCl3 (50 mL/50 mL). The CHCl3 layer was washed with sat. NaCl solution (50 mL), dried (Na2SO4), and evaporated. The residue was chromatographed on a silica column (1.9×20 cm, eluted with CHCl3, 1%, 2%, 4% MeOH/CHCl3). Evaporation of fractions 42-51 (15 mL per fraction) and recrystallization from MeOH gave 0.178 g (2 crops, 45%) of 42a as white crystals. MP: 82°-87° C. MS: (EI) m/e 393.9875 (20%, M+ =393.9890). 1H NMR (DMSO-d6): d 8.00, 7.96 (2×s, 2, 7-H and 4-H), 5.91 (d, 1, 1'-H, J1'-2' =7.5 Hz), 5.59 (d, 1, 2'-OH, J2'-2'OH =6.0 Hz), 5.45 (d, 1, 3'-OH, J3'-3'OH =4.5 Hz), 4.44 (dd, 1, 5'-H, J5'-4' =4.5 Hz, J5'-5" =12.5 Hz), 4.42 (m, 1, 2'-H, J2'-3' =6.0 Hz), 4.25 (dd, 1, 5"-H, J5"-4' =2.5 Hz), 4.17 (m, 1, 4'-H, J3'-4' =3.5 Hz), 4.11 (m, 1, 3'-H), 2.14 (s, 3, 5'-OAc). 13C NMR (DMSO-d6): d 169.95 (COCH3), 142.03 (C2), 140.92 (C3a), 132.30 (C7a), 125.96, 125.86 (C5 and C6), 120.28 (C4), 113.47 (C7), 89.32 (C1'), 82.63 (C4'), 71.41 (C2'), 69.03 (C3'), 63.35 (C5'). 20.56 (COCH3). Anal. Calcd. for C14H13Cl3N2O5 : C, 42.50; H, 3.31; N, 7.08. Found: C, 42.45; H, 3.20; N, 6.97.
