Beilstein J. Org. Chem. 2011, 7, 1182–1188.
169.6 (3 COCH3), 138.0–127.6 (Ar-C), 92.8 (C-1D), 81.0 stir for 1 h at same temperature. The reaction mixture was
(C-1C), 79.4 (C-3C), 75.5 (PhCH2), 74.6 (C-3C), 74.2 (C-2C), filtered through a bed of Celite® and washed with CH2Cl2
71.8 (PhCH2), 70.4 (C-3D), 68.4 (C-5C), 68.1 (C-4D), 67.3 (100 mL). The organic layer was successively washed with 5%
(C-5D), 61.5 (C-6D), 60.6 (C-2D), 25.4 (SCH2CH3), 20.7, 20.6, aq. Na2S2O3, NaHCO3 solution and water, dried (Na2SO4) and
20.5 (3 COCH3), 17.7 (CCH3), 14.9 (SCH2CH3); ESIMS m/z: concentrated under reduced pressure. The crude product was
724.2 [M + Na]+; anal. calcd for C34H43N3O11S (701.26): C, purified over silica gel using hexane–EtOAc (2:1) as eluant to
58.19; H, 6.18; found: C, 58.0; H, 6.42.
give pure compound 8 (2.0 g, 82%). White solid; mp 66–68 °C;
[α]D25 +18.2 (c 1.2, CHCl3); IR (KBr): 3428, 3032, 2932, 2108,
Ethyl (2-azido-3,4,6-tri-O-benzyl-2-deoxy-α-D-glucopyra- 1753, 1508, 1455, 1368, 1230, 1044, 740, 698 cm−1; 1H NMR
nosyl)-(1→3)-2,4-di-O-benzyl-1-thio-α-L-rhamnopyra- (600 MHz, CDCl3) δ 7.35–7.05 (m, 30H, Ar-H), 6.91 (d, J =
noside (7): To a solution of compound 6 (2.0 g, 2.85 mmol) in 9.0 Hz, 2H, Ar-H), 6.80 (J = 9.0 Hz, 2H, Ar-H), 5.34 (d, J =
THF (10 mL) powdered NaOH (1.0 g, 25 mmol), benzyl bro- 4.5 Hz, 1H, H-1B), 5.29 (t, J = 10.0 Hz, 1H, H-3A), 5.27 (t, J =
mide (2.1 mL, 17.6 mmol) and n-Bu4NBr (50 mg) were added 9.0 Hz, 1H, H-3B), 5.04 (dd, J = 8.0 Hz each, 1H, H-2A), 4.97
and the reaction mixture was allowed to stir at rt for 2 h. The (d, J = 3.5 Hz, 1H, H-1D), 4.95 (d, J = 8.0 Hz, 1H, H-1A), 4.89
reaction mixture was poured into water and extracted with (d, J = 2.0 Hz, 1H, H-1C), 4.85–4.80 (m, 2H, PhCH2),
CH2Cl2 (100 mL). The organic layer was washed with water, 4.78–4.75 (m, 3H, H-2B, PhCH2), 4.65 (d, J = 12.0 Hz, 1H,
dried (Na2SO4) and concentrated under reduced pressure. The PhCH2), 4.60 (d, J = 12.0 Hz, 1H, PhCH2), 4.58–4.44 (m, 5H,
crude product was purified over silica gel using hexane–EtOAc PhCH2), 4.41 (dd, J = 12.5, 2.5 Hz, 1H, H-6aA), 4.35 (d, J =
(6:1) as eluant to give pure compound 7 (2.2 g, 91%). Yellow 12.0 Hz, 1H, PhCH2), 4.21 (dd, J = 12.5, 2.5 Hz, 1H, H-6bA),
oil; [α]D25 +12.0 (c 1.2, CHCl3); IR (neat): 3430, 3031, 2925, 4.05–4.01 (2 t, J = 9.5 Hz each, 2H, H-3D, H-4C), 3.98–3.92 (m,
2107, 1642, 1496, 1454, 1361, 1215, 1091, 1051, 1028, 751, 2H, H-3c, H-5c), 3.90 (t, J = 10.0 Hz, 1H, H-4D), 3.81 (t, J =
697 cm−1; 1H NMR (600 MHz, CDCl3) δ 7.45–7.07 (m, 25H, 8.5 Hz, 1H, H-4A), 3.77 (s, 3H, OCH3), 3.76–3.74 (m, 1H,
Ar-H), 5.32 (br s, 1H, H-1C), 4.93 (d, J = 3.6 Hz, 1H, H-1D), H-4B), 3.72–3.71 (m, 1H, H-5B), 3.69–3.65 (m, 2H, H-5A,
4.85 (br s, 2H, PhCH2), 4.83 (d, J = 10.2 Hz, 1H, PhCH2), 4.77 H-6aB), 3.63–3.61 (m, 1H, H-6aD), 3.58–3.55 (m, 3H, H-2C,
(d, J = 10.8 Hz, 1H, PhCH2), 4.74 (d, J = 12.0 Hz, 1H, PhCH2), H-5D, H-6bB), 3.53–3.51 (m, 1H, H-6bD), 3.43 (dd, J = 10.0, 3.5
4.69 (d, J = 12.0 Hz, 1H, PhCH2), 4.60 (d, J = 12.6 Hz, 1H, Hz, 1H, H-2D), 2.04, 2.02, 2.01, 1.99, 1.95 (5 s, 15H,
PhCH2), 4.55 (d, J = 10.2 Hz, 1H, PhCH2), 4.48 (d, J = 5 COCH3), 1.25 (d, J = 6.2 Hz, 3H, CCH3); 13C NMR
10.8 Hz, 1H, PhCH2), 4.35 (d, J = 12.6 Hz, 1H, PhCH2), 4.07 (150 MHz, CDCl3) δ 170.7, 170.2 (2C), 169.8, 169.7
(t, J = 9.6 Hz, 1H, H-3D), 4.04–3.99 (m, 3H, H-3C, H-5C, (5 COCH3), 155.7–114.5 (Ar-C), 99.7 (C-1A), 98.8 (C-1C), 96.0
H-5D), 3.93 (br s, 1H, H-2C), 3.79 (t, J = 9.6 Hz, 1H, H-4C), (C-1B), 93.9 (C-1D), 80.2 (C-3D), 79.4 (C-4D), 78.2 (C-5A),
3.66 (t, J = 9.6 Hz, 1H, H-4D), 3.60 (dd, J = 10.8, 2.4 Hz, 1H, 77.2 (C-5B), 75.5 (PhCH2), 75.4 (C-3A), 75.3 (PhCH2), 74.8
H-6aD), 3.51 (dd, J = 10.8, 1.2 Hz, 1H, H-6aD), 3.40 (dd, J = (PhCH2), 74.3 (C-2B), 74.2 (C-4C), 73.7 (PhCH2), 73.3
10.2, 3.6 Hz, 1H, H-2D), 2.60–2.50 (m, 2H, SCH2CH3), 1.35 (d, (PhCH2), 72.6 (2C, C-5D, PhCH2), 72.2 (C-4A), 72.1 (C-2A),
J = 6.0 Hz, 3H, CCH3), 1.22 (t, J = 7.8 Hz, 3H, SCH2CH3); 71.3 (C-4B), 70.7 (2C, C-3C, C-5C), 70.4 (C-3B), 69.0 (C-2C),
13C NMR (150 MHz, CDCl3) δ 137.7–127.5 (Ar-C), 93.2 67.9 (C-6B), 67.8 (C-6D), 63.3 (C-2D), 62.6 (C-6A), 55.6
(C-1D), 81.1 (C-1C), 80.2 (C-3D), 79.8 (C-4D), 78.1 (C-4C), (OCH3), 21.0, 20.9, 20.7, 20.6 (2C) (5 COCH3), 17.9 (CCH3);
75.9 (PhCH2), 74.8 (PhCH2), 74.5 (C-3C), 74.4 (C-2C), 73.3 ESIMS m/z: 1554.6 [M + Na]+; anal. calcd for C83H93N3O25
(PhCH2), 71.8 (PhCH2), 70.4 (C-5C), 68.3 (C-5D), 67.8 (C-6D), (1531.61): C, 65.04; H, 6.12; found: C, 64.82; H, 6.36.
63.0 (C-2D), 25.4 (SCH2CH3), 17.8 (CCH3), 14.9 (SCH2CH3);
ESIMS m/z: 868.3 [M + Na]+; anal. calcd for C49H55N3O8S 4-Methoxyphenyl (2-acetamido-2-deoxy-α-D-glucopyra-
(845.37): C, 69.56; H, 6.55; found: C, 69.33; H, 6.80.
nosyl)-(1→3)-(α-L-rhamnopyranosyl)-(1→4)-(α-D-glucopy-
ranosyl)-(1→4)-sodium β-D-glucopyranosid uronate (1): A
4-Methoxyphenyl (2-azido-3,4,6-tri-O-benzyl-2-deoxy-α-D- solution of compound 8 (1.3 g, 0.85 mmol) in 0.1 M CH3ONa
glucopyranosyl)-(1→3)-(2,4-di-O-benzyl-α-L-rhamnopyra- in CH3OH (25 mL) was allowed to stir at rt for 3 h and neutral-
nosyl)-(1→4)-(2,3-di-O-acetyl-6-O-benzyl-α-D-glucopyra- ized with Dowex 50W X8 (H+) resin. The reaction mixture was
nosyl)-(1→4)-2,3,6-tri-O-acetyl-β-D-glucopyranoside (8): To filtered and concentrated under reduced pressure. To a solution
a solution of compound 2 (1.2 g, 1.60 mmol) and compound 7 of the crude product in CH2Cl2 (25 mL) and H2O (4 mL) were
(1.6 g, 1.89 mmol) in anhydrous CH2Cl2 (8 mL) MS 4Å (2.0 g) sequentially added aq. NaBr (2 mL, 1 M), aq. TBAB (2.5 mL,
was added and the reaction mixture was cooled to −10 °C. 1 M), TEMPO (100.0 mg, 0.64 mmol), satd. NaHCO3 solution
To the cooled reaction mixture NIS (500.0 mg, 2.22 mmol) (10 mL) and 4% aq. NaOCl (15 mL) were added and the reac-
and HClO4–SiO2 (20.0 mg) were added and it was allowed to tion mixture was allowed to stir at 0–5 °C for 2 h. The reaction
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