ABSTRACT
METHYL (PHENYL 5-ACETAMIDO-4,7,8,9-TETRA-O-ACETYL-3,5-DIDEOXY2-THIO-D-GLYCERO-α-D-GALACTO-NON-2-ULOPYRANOSID)ONATE (6) Methyl (5-acetamido-2,4,7,8,9-penta-O-acetyl-3,5-dideoxy-d-glycero-d-galactonon-2-ulopyranos)onate 413 (100 mg, 0.188 mmol) was dissolved in acetyl chloride (1.2 mL) under argon. The solution was cooled to 0°C, methanol (0.06 mL) was added dropwise and the mixture was stirred at rt until TLC showed that the reaction was complete (~2 h). The mixture was concentrated and dried at rt in vacuo for 1 h. The residue containing crude methyl (5-acetamido-4,7,8,9-tetra-O-acetyl3,5-dideoxy-d-glycero-d-galacto-2-nonulopyranosyl chloride)onate 5 (~90 mg) was dissolved in anhydrous CH2Cl2 (0.94 mL) and thiophenol (29 μL, 0.28 mmol) was added with stirring under argon at rt, followed by the dropwise addition of N,Ndiisopropylethylamine (DIPEA, 46 μL, 0.28 mmol). The mixture was stirred at rt overnight until TLC showed that the reaction was complete. After concentration, chromatography (hexane-EtOAc, gradient, starting with 10% EtOAc) afforded the title compound 6 (86 mg, 79%). Analytical data for 6: Rf = 0.32 (2:3 acetone-toluene); mp 142°C-144°C (toluene-hexanes); Ref. [9] mp 139°C-140°C (from benzenehexanes); [α]D24 +19° (c 1, CHCl3); Ref. [9] [α]D +21° (c 0.9, CHCl3); 1H NMR (CDCl3): δ 1.78, 1.94, 1.97, 1.98 (4 s, 12H, 4 × –COCH3), 2.06 (s, 1H, H-3a). 2.73 (ddd, J3e,4 4.6 Hz, H-3e), 3.49 (s, 3H, –OCH3), 3.89 (dd, J6,7 4.6 Hz, H-6), 3.97 (dd, J5,6 10.2 Hz, H-5), 4.14 (ddd, J8,9b 5.6 Hz, H-9b), 4.32 (ddd, J9a,9b 10.2 Hz, H-9a), 4.81 (ddd, 1H, J4,5 10.3 Hz, H-4), 5.16-5.25 (m, 2H, H-7.8), 5.49 (d, 1H, J5,NH 9.8 Hz, –NH), 7.20-7.45 (m, 5H, aromatic) ppm; 13C NMR (CDCl3): δ, 20.8, 20.9 (×2), 21.1, 23.2, 38.2, 49.2, 52.8, 62.2, 67.9, 69.8, 70.2, 74.9, 87.6, 128.7, 128.9 (×2), 130.0, 136.6 (×2), 168.0, 170.1, 170.2, 170.3, 170.8, 171.0 ppm; HR-FAB MS [M + Na]+ calcd for C26H33NO12SNa 606.1621; found: 606.1622. Anal. calcd for C26H33NO12S: C, 53.51; H, 5.70; N, 2.40. Found: C,53.59; H, 5.68; N, 2.36.
