270
Suhr and Thiem
10b (868 mg, 2.41 mmol, 18%) and a mixture of the anomers 10b and 10a (1.600 g,
4.43 mmol, 33%) were obtained. 10b: Fine needles; mp: 107.8–108.58C; [a]2D0 ¼ 261.8
1
(c ¼ 0.6, CHCl3); TLC (PE/EA 3 : 1): Rf ¼ 0.24 (UV, H2SO4); H NMR (400 MHz,
CDCl3): d ¼ 7.28–7.20 (m, 10H, 2ꢂC6H5CH2O), 4.77, 4.72 (2ꢂ d, 2ꢂ 1H, C6H5CH2O,
2
2J ¼ 11.4 Hz), 4.62, 4.57 (2ꢂ d, 2ꢂ 1H, C6H5CH2O, J ¼ 11.4 Hz), 4.37 (d, 1H, H-1,
3
2
3J1,2 ¼ 7.1 Hz), 4.08 (dd, 1H, H-5eq, J4,5eq ¼ 3.7, J5eq,5ax ¼ 12.0 Hz), 3.58–3.45
(m, 3H, H-2, H-3, H-4), 3.32 (dd, 1H, H-5ax, 3J4,5ax ¼ 7.8, 2J5eq,5ax ¼ 12.0 Hz), 2.35 (bs,
1H, 2-OH), 2.10 (s, 3H, SCH3) ppm; 13C NMR (100.62 MHz, CDCl3): d ¼ 138.44,
128.66–128.62, 128.11–127.97 (2ꢂ C6H5CH2O), 87.04 (C-1), 81.61, 76.69, 71.34 (C-2,
C-3, C-4), 74.45, 72.91 (C6H5CH2O), 65.35 (C-5), 13.03 (SCH3) ppm.
Anal. calcd for C20H24O4S (360.46): C 66.64, H 6.71. Found: C 66.30, H 6.51.
1
10a: TLC (PE/EA 3 : 1): Rf ¼ 0.19 (UV, H2SO4); H NMR (400 MHz, CDCl3):
3
d ¼ 7.28–7.20 (m, 10H, 2ꢂ C6H5CH2O), 4.95 (d, 1H, H-1, J1,2 ¼ 3.6 Hz), 4.72–4.58
3
2
(m, 4H, 2ꢂ C6H5CH2O), 4.04 (dd, 1H, H-5eq, J4,5eq ¼ 3.6, J5eq,5ax ¼ 12.2 Hz), 3.88–
3.48 (m, 4H, H-2, H-3, H-4, H-5ax), 3.18 (m, 1H, 2-OH), 2.21 (s, 3H, SCH3) ppm.
Methyl 3,4-Di-O-benzyl-2-O-p-methoxybenzoyl-1-thio-a-D-xylopyranoside (11a)
and
methyl
3,4-di-O-benzyl-2-O-p-methoxybenzoyl-1-thio-b-D-xylopyranoside
(11b). Compound 10 (210 mg, 0.58 mmol) was dissolved in pyridine (2 mL). The solution
was cooled in an ice bath and p-methoxybenzoyl chloride (0.16 mL, 200 mg, 1.17 mmol)
was added in portions and stirred for 14 hr at RT. Then another portion of p-methoxyben-
zoyl chloride (0.08 mL, 100 mg, 0.59 mmol) was added, and stirring continued for another
24 hr at RT. The reaction was stopped by cooling in an ice bath, addition of methanol
(1 mL) and stirring for 1 hr. The crude product was purified by flash chromatography
with PE/EA 3 : 1 to give the a-anomer 11a (45 mg, 0.09 mmol, 16%), the b-anomer
11b (99 mg, 0.20 mmol, 36%) and a mixture of the anomers (83 mg, 0.17 mmol, 29%);
total yield of 11: 227 mg (0.46 mmol, 79%). 11a: colorless solid; mp: 99.6–100.38C;
[a]2D0 ¼ 218.9 (c ¼ 0.4, CHCl3); TLC (PE/EA 3 : 1): Rf ¼ 0.36 (UV, H2SO4); 1H
NMR (400 MHz, CDCl3): d ¼ 7.98 (ddd, 2H, b-CH3OC6H4COO, 3J ¼ 9.2,
4J ¼ 2.0 Hz), 7.34–7.18 (m, 10H, 2ꢂ C6H5CH2O), 6.91 (ddd, 2H, g-CH3OC6H4COO,
4
3
3
3J ¼ 9.2, J ¼ 2.0 Hz), 5.46 (d, 1H, H-1, J1,2 ¼ 5.6 Hz), 5.21 (dd, 1H, H-2, J1,2 ¼ 5.1,
3J2,3 ¼ 9.2 Hz), 4.82 (d, 1H, C6H5CH2O, 2J ¼ 11.2 Hz), 4.78 (d, 1H, C6H5CH2O,
2J ¼ 11.2 Hz), 4.74 (d, 1H, C6H5CH2O, 2J ¼ 11.7 Hz), 4.64 (d, 1H, C6H5CH2O,
2J ¼ 11.7 Hz), 4.03–3.93 (m, 2H, H-3, H-5a), 3.86 (s, 3H, CH3OC6H4COO), 3.77–3.64
(m, 2H, H-4, H-5b), 2.03 (s, 3H, SCH3) ppm; 13C NMR (100.67 MHz, CDCl3):
d ¼ 165.45 (CH3OC6H4COO), 163.79 (d-CH3OC6H4COO), 138.30 (quart-C6H5CH2O),
132.12 (b-CH3OC6H4COO), 128.59, 128.45, 128.06, 127.97, 127.93, 127.78
(2ꢂ C6H5CH2O), 122.16 (a-CH3OC6H4COO), 113.89 (g-CH3OC6H4COO), 83.99
(C-1), 79.19 (C-3), 77.79 (C-4), 75.34, 73.47 (2ꢂ C6H5CH2O), 73.05 (C-2), 60.92 (C-
5), 55.61 (CH3OC6H4COO), 12.92 (SCH3) ppm. 11b: Colorless needles; mp: 177.2–
178.08C; [a]2D0 ¼ þ 40.7 (c ¼ 0.8, CHCl3); TLC (PE/EA 3:1): Rf ¼ 0.27 (UV,
1
3
H2SO4); H NMR (400 MHz, CDCl3): d ¼ 7.98 (ddd, 2H, b-CH3OC6H4COO, J ¼ 8.7,
4J ¼ 3.1, 2.0 Hz), 7.34–7.13 (m, 10H, 2ꢂ C6H5CH2O), 6.91 (ddd, 2H, g-CH3OC6H4-
3
4
3
3
COO, J ¼ 9.2, J ¼ 2.5, 2.0 Hz), 5.23 (dd ꢀ t, 1H, H-2, J1,2 ¼ 8.7, J2,3 ¼ 8.6 Hz),
2
2
4.77 (d, 1H, C6H5CH2O, J ¼ 11.2 Hz), 4.72 (d, 1H, C6H5CH2O, J ¼ 8.6 Hz), 4.69
2
2
(d, 1H, C6H5CH2O, J ¼ 8.1 Hz), 4.63 (d, 1H, C6H5CH2O, J ¼ 11.7 Hz), 4.44 (d, 1H,
3
3
2
H-1, J1,2 ¼ 8.7 Hz), 4.14 (dd, 1H, H-5eq, J4,5eq ¼ 4.6, J5eq,5ax ¼ 11.7 Hz), 3.86
(s, 3H, CH3OC6H4COO), 3.78–3.67 (m, 2H, H-3, H-4), 3.38 (dd, 1H, H-5ax,