Benzothiazole and Benzoxazole Nucleosides
2071
13e: MS; m=z: 481 (Mþ). Calculated for C21H23NO10S (481.47): C, 52.39; H,
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4.81; N, 2.91. Found: C, 52.20; H, 4.96; N, 2.68. [a]D þ 11.5ꢀ (c 0.7, CHCl3). H-
NMR (CDCl3): d 1.98, 2.02, 2.08, 2.19 (4s, 12H, 4 Ac), 4.14–4.29 (m, 3H, 5-H0,
60-H, 600-H), 5.22 (dd, J ¼ 3.4, 9.9 Hz, 1H, 40-H), 5.30 (dd, J ¼ 10.1, 10.1 Hz, 1H,
20-H), 5.44 (dd, J ¼ 3.4, 10.0 Hz, 1H, H-30), 5.72 (d, J ¼ 10.2 Hz, 1H, 10-H), 7.20–
7.70 (m, 4H, Ar-H). 13C-NMR (CDCl3): d 20.5, 20.6, 20.6, 20.7 (4 Ac), 61.2 (C-
60), 67.0 (C-20), 67.1 (C-30), 71.7 (C-40), 75.0 (C-50), 83.9 (C-10), 110.2, 118.9, 124.7,
125.9, 141.5, 151.9 (C-Ar), 161.0 (C-2), 169.7, 169.9, 170.2, 170.4 (4 CO).
14b: MS; m=z: 481 (Mþ). Calculated for C21H23NO10S (481.47): C, 52.39; H,
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4.81; N, 2.91. Found: C, 52.28; H, 4.94; N, 2.72. H-NMR (CDCl3): d 2.00, 2.03,
2.07, 2.22 (4s, 12H, 4 Ac), 4.16–4.30 (m, 3H, 50-H, 60-H, 600-H), 5.24 (dd, J ¼ 9.6,
10.1 Hz, 1H, 40-H), 5.38 (dd, J ¼ 9.2, 9.5 Hz, 1H, 20-H), 5.63 (dd, J ¼ 9.4, 9.4 Hz,
1H, 30-H), 6.32 (d, J ¼ 9.1 Hz, 1H, 10-H), 7.20–7.50 (m, 4H, Ar-H).
5-Methoxy-2-(20,30,40,60-tetra-O-acetyl-b-d-galactopyranosylmercapto)benzothia-
zole (13f) and 5-Methoxy-3-(20,30,40,60-tetra-O-acetyl-b-d-galactopyranosyl)-2-thio-
benzothiazole (14c). From 1c (1.15 g, 5.0 mmol) and 12 (2.26 g, 5.5 mmol) in the
manner described for 13a and 14a. Yield 1.60 g (60%) of 13f as pale yellow foam
and 0.58 g (22%) of 14c as pale yellow foam.
13f: MS; m=z: 527 (Mþ). Calculated for C22H25NO10S2 (527.56): C, 50.09; H,
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4.78; N, 2.66. Found: C, 50.26; H, 5.16; N, 2.52. H-NMR (CDCl3): d 1.98, 2.02,
2.08, 2.19 (4s, 12H, 4 Ac), 3.82 (s, 3H, OCH3), 4.12–4.32 (m, 3H, 5-H0, 60-H, 600-H),
5.22 (dd, J ¼ 3.4, 9.8 Hz, 1H, 40-H), 5.30 (dd, J ¼ 10.1, 10.1 Hz, 1H, 20-H), 5.45
(d, J ¼ 3.4 Hz, 1H, H-30), 5.74 (d, J ¼ 10.2 Hz, 1H, 10-H), 7.15–7.65 (m, 3H, Ar-H).
14c: MS; m=z: 527 (Mþ). Calculated for C22H25NO10S2 (527.56): C, 50.09; H,
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4.78; N, 2.66. Found: C, 49.92; H, 5.10; N, 2.94. H-NMR (CDCl3): d 2.00, 2.03,
2.07, 2.22 (4s, 12H, 4 Ac), 3.86 s, 3H, OCH3), 4.20–4.36 (m, 3H, 50-H, 60-H, 600-H),
5.24 (dd, J ¼ 9.6, 10.2 Hz, 1H, 40-H), 5.38 (dd, J ¼ 9.3, 9.5 Hz, 1H, 20-H), 5.64 (dd,
J ¼ 9.4, 9.4 Hz, 1H, 30-H), 6.33 (d, J ¼ 9.1 Hz, 1H, 10-H), 7.05–7.53 (m, 3H, Ar-H).
2-(b-d-Glucopyranosylmercapto)benzothiazole (15a). From 13a (0.50 g, 1.0 mmol)
of 13a in the manner described for 5a. The product was chromatographed on silica
gel using MeOH, in gradient, (0–10%) and CH2Cl2, as eluent to give 15a (0.28 g,
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86%) as a white foam (lit.,[32] mp 110–180ꢀC, 75%). MS; m=z: 329 (Mþ). H-NMR
(CD3OD-d4): d 3.17–3.36 (m, 4H, 40-H, 50-H, 60-H, 600-H), 3.60 (dd, J ¼ 4.3, 9.3 Hz,
1H, 20-H), 3.78 (dd, J ¼ 1.6, 12.0 Hz, 1H, 30-H), 5.57 (d, 1H, J ¼ 9.1 Hz, 10-H); 7.20–
7.78 (m, 4H, Ar-H).
2-(b-d-Glucopyranosylmercapto)benzoxazole (15b). From 13b (0.73 g, 1.0 mmol)
of 13b in the manner described for 5a. Yield 0.25 g (80%) as white foam. MS; m=z: 313
(Mþ). Calculated for C13H15NO6S (313.32): C, 49.83; H, 4.82; N, 4.47. Found: C,
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49.59; H, 4.98; N, 4.60. [a]D ꢁ106ꢀ (c 0.5, MeOH). H-NMR (CD3OD-d4): d 3.15–
3.36 (m, 4H, 40-H, 50-H, 60-H, 600-H), 3.60 (dd, J ¼ 4.2, 9.4 Hz, 1H, 20-H), 3.78 (dd,
J ¼ 1.6, 12.1 Hz, 1H, 30-H), 5.57 (d, J ¼ 9.4 Hz, 1H, 10-H), 7.00–8.00 (m, 4H, Ar-H).
5-Methoxy-2-(b-d-glucopyranosylmercapto)benzothiazole (15c). From 13c
(0.53 g, 1.0 mmol) in the manner described for 5a. Yield 0.30 g (84%) as a white solid,