386
K. Larsen et al. / Carbohydrate Research 343 (2008) 383–387
73.5, 73.2 (2CH2Ph), 68.6 (C-6). MS (FAB): m/z = 706.4
(dd, 1H, J 1.9 Hz, H-2), 3.82 (dd, 1H, J 9.5 Hz, H-4),
3.71 (dd, 1H, J 1.9 Hz, J 10.3 Hz, H-6a), 3.69–3.57 (m,
2H, H-3, H-6b), 3.46 (ddd, 1H, J 2.0 Hz, J 6.0, J
9.6 Hz, H-5); 13C NMR (CDCl3): d 138.2–127.5
(C-arom, PhCH2) 84.4 (C-3), 83.3 (C-1a), 77.2 (C-2),
76.2 (C-5), 75.1 (CH2Ph), 75.0 (C-4), 74.9, 73.4, 72.5
(3CH2Ph), 69.5 (C-6). MS (FAB): m/z = 562.4
[M+Na]+.
[M+Na]+.
1.2.3. N-Trichloroacetyl-2,3,6-tri-O-benzyl-4-O-(2,3,4,6-
tetra-O-benzyl-a-D-glucopyranosyl)-a/b-D-glucopyranosyl-
amine (7c). The residue was chromatographed on silica
gel (90 g) with 40% Et2O in n-pentane to give 7c
(650 mg, colourless syrup, 67% yield, a/b 3:1); [a]D
1
+24.0ꢁ (c 10.0 · 10ꢀ3 CHCl3) H NMR data (CDCl3):
d 5.67 (dd, 0.8H, J 3.2 Hz, J 6.6 Hz, H-1, a-anomer),
5.47 (d, 0.2H, J 3.82 Hz, H-10, b-anomer), 5.35 (d,
0.8H, J 3.5 Hz, H-10, a-anomer), 5.20 (dd, 0.2H, J
8.7 Hz, H-1, b-anomer). 13C NMR (CDCl3): For the
a-anomer: d 161.9 (C@O), 97.1 (C-10), 92.4 (CCl3),
75.8 (C-1). For the b-anomer: d 161.4 (C@O), 97.2
(C-10), 92.2 (CCl3), 80.6 (C-1). MS (FAB): m/z =
1138.4 [M+Na]+.
1.3.3. 2,3,6-Tri-O-benzyl-4-O-(2,3,4,6-tetra-O-benzyl-a-
D-glucopyranosyl)-a/b-D-glucopyranosylamine (8c). To
the 100% EtOH solution was added 2 mL of toluene
to ensure total solubility of 7c, which was chromato-
graphed on silica gel (70 g) with 5% MeOH in CH2Cl2
to give N-substituted glycosylamine 9c (380 mg, colour-
less syrup, 78% yield, a/b 1:1); [a]D +43.2ꢁ (c 9.5 · 10ꢀ3
CHCl3); 1H NMR data (CDCl3): d 6.83 (dd, 0.5 H, NH),
6.46 (d, 0.5H, NH), 5.88 (dd, 0.5H, H-1, a-anomer), 5.47
(d, 0.5H, J 3.82 Hz, H-10, b-anomer), 5.35 (d, 0.5H,
H-10, a-anomer), 5.20 (dd, 0.5H, H-1, b-anomer); 13C
NMR (CDCl3): For the a-anomer: d 96.4 (C-10), 76.2
(C-1); for the b-anomer: d 96.7 (C-10), 79.5 (C-1). MS
(FAB): m/z = 994.6 [M+Na]+.
1.3. General procedure for the reduction of the
N-trichloroacetylglycosylamines
NaBH4 powder (2.9 mmol) was added to a solution of
the trichloroacetamide derivatives 7a–c (0.73 mmol) in
absolute EtOH (5 mL). After 15 min the reactions were
stopped by addition of acetone (excess) and the reaction
mixtures were stirred for additional 15 min. The mix-
tures were concentrated under vacuum and extracted
with EtOAc. The organic phases were washed with
water until neutral, dried, filtered and evaporated. The
residues were purified by column chromatography.
Acknowledgements
This work was financially supported by the Danish Na-
tional Research Foundation, by EU FAIR programme
contract CT95-0568, and by the Danish Directorate
for Development (Non-food program). Birger Lindberg
Møller is thanked for commenting on the manuscript.
1.3.1. 2,3,4,6-Tetra-O-benzyl-a/b-D-glucopyranosylamine
(8a). The residue was chromatographed on silica gel
(60 g) with 80% Et2O in n-pentane to give N-substituted
glycosylamine 8a (230 mg, colourless syrup, 91% yield,
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1
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