310
D.K. Watt et al. / Carbohydrate Research 325 (2000) 300–312
Table 4
15 [1.05 g, 1.35 mmol, 75% from 7; TLC (1:2
EtOAc–hexanes), Rf 0.15]. Crystallisation
from ether–hexanes gave 15 (0.87 g, 1.12
mmol, 62% from 7) as white crystals: mp
Intra- and intermolecular hydrogen bonds for 2 a
,
DꢀH…A
Distance (A)
Angle (°)
(DꢀH…A)
171.5
1
113 °C; [h]D −16° (c 1.0, CHCl3); H NMR
(H…A)
1.91
2.07
2.01
1.94
2.19
1.93
2.39
1.86
(D…A)
2.726(5)
2.830(5)
2.792(5)
2.725(5)
2.959(5)
2.739(3)
3.172(5)
2.634(5)
data (200 MHz, CDCl3): l 1.66 [br s, 1 H,
OH], 3.24 (dd, 1 H, J 12 and J 8 Hz), 3.38
(dd, 1 H, J 10 and J 3 Hz), 3.43 (s, 3 H,
CH3O), 3.48–3.69 (m, 6 H), 3.84–3.96 (m, 3
H), 4.29–4.95 (m, 12 H), 7.20–7.40 (m, 25 H,
5×Ph); 13C NMR (75 MHz, CDCl3): l 57.2
(CH3O), 62.5 (C-5), 68.7 (C-6%), 72.6 (CH2Ph),
72.8 (CH2Ph), 72.9, 73.4 (CH2Ph), 73.7, 74.0,
74.5 (CH2Ph), 75.2 (CH2Ph), 77.6, 80.6, 81.2,
81.4, 103.8 (C-1), 104.7 (C-1%), 127–129, 137.8,
137.8, 137.9, 138.6, 138.8; FABMS m/z
777 ([MH]+, 1%), 775 ([M−H]+, 1%), 745
([M−CH3O]+, 2%), 637 (2%), 371 (6%), 327
(16%), 307 (6%), 289 (8%), 283 (41%), 239
(75%), 195 (88%), 181 (81%), 150 (100%).
Anal. Calcd for C47H52O10: C, 72.66; H, 6.75.
Found C, 72.75; H, 6.70.
O(2¦)ꢀH(2A)
…O(1W)c1
O(3¦)ꢀH(3A)
…O(1W)c2
O(4¦)ꢀH(4A)
…O(5)c3
O(3%)ꢀH(3%1)
…O(2¦)
O(4%)ꢀH(4%1)
…O(3)c4
O(6%)ꢀH(6%)
…O(6%)c5
O(3)ꢀH(3%2)
…O(5¦)
154.5
159.9
159.8
155.7
171.3
160.6
O(4)ꢀH(4%2)
…O(3%)c6
157.3
a
,
D–H is 0.82 A. Symmetry transformations used to gener-
ate equivalent atoms: c1 x+1/2, −y+3/2, −z+1; c2
x−1/2, −y+3/2, −z+1; c3 −x+3/2, −y+2, z−1/2; c4
−x+2, y−1/2, −z+3/2; c5 x−1/2, −y+3/2, −z+2; c6
−x+2, y+1/2, −z+3/2.
Methyl h-
L
-fucopyranosyl-(12)-i-
D
-gal-
actopyranosyl-(12)-i-
D
-xylopyranoside (3).
—Freshly prepared bromide 11 (0.191 g,
0.371 mmol) was added to a mixture of 15
(0.285 g, 0.367 mmol), dry tetraethylammo-
nium bromide (0.320 g, 1.53 mmol), and pow-
mmol) in CH2Cl2 (6.0 mL) was added, and the
solution was stirred for 10 min. The reaction
mixture was warmed to −40 °C and stirred
for a further 30 min. The solution was neu-
tralised with triethylamine, washed with ice-
cold aq 1 M sodium thiosulfate, and filtered
through Celite®. The filtrate was washed with
1 M HCl, satd aq NaHCO3, water, and dried
over MgSO4. Removal of the solvent in vacuo
gave methyl 2-O-acetyl-3,4,6-tri-O-benzyl-b-
,
dered 4 A molecular sieve (0.860 g) in anhyd
CH2Cl2 (7.4 mL), and the mixture was shaken
for 5 days at ambient temperature. The solids
were removed by filtration through Celite®,
and CH2Cl2 (100 mL) was added. The filtrate
was washed twice with water (100 mL), while
extracting each wash with CH2Cl2 (50 mL).
The CH2Cl2 extracts were combined and dried
(MgSO4) and concentrated to a syrup in
vacuo. The product was purified by silica-gel
column chromatography (1:2 EtOAc–hexanes
as eluent; TLC, Rf 0.59) to give methyl 2,3,4-
D-galactopyranosyl-(12)-3,4-di-O-benzyl-b-
D-xylopyranoside (14) (1.61 g) as a slightly
1
impure clear syrup. H NMR data (200 MHz,
CDCl3): inter alia l 1.77 (s, 3 H, OAc), 3.39
(CH3O), 5.39 (dd, 1 H, J 10 and 8 Hz, H-2%),
7.20–7.40 (m, 25 H, 5×Ph).
tri-O-benzyl-a-
tri-O-benzyl-b-
di-O-benzyl-b-
L
-fucopyranosyl-(12)-3,4,6-
-galactopyranosyl-(12)3,4-
D
Crude 14 (1.60 g, 1.95 mmol) was dissolved
in ether (50 mL) and MeOH (50 mL) contain-
ing a small amount of NaOMe. The mixture
was stirred for 24 h and concentrated.
Dichloromethane (200 mL) was added, and
the solution was washed with water until neu-
tral and dried over MgSO4. Removal of the
solvent in vacuo and purification of the
residue by silica-gel column chromatography
(silica-gel, 1:2 EtOAc–hexanes as eluent) gave
D
-xylopyranoside (16) (0.309 g)
1
as a slightly impure syrup: H NMR (200
MHz, CDCl3) inter alia l 1.15 (d, 3 H, J 6.5
Hz, H-6¦), 3.19–4.24 (m, 15 H), 3.41 (s, 3 H,
CH3O), 4.38–5.01 (m, 18 H), 5.76 (d, 1 H, J
3.5, H-1¦), 6.98–7.52 (m, 40 H, 8×Ph); 13C
NMR (75 MHz, CDCl3): l 16.7 (C-6¦), 56.3
(CH3O), 63.3 (C-5), 66.3 (C-5¦), 68.4 (C-6%),
[71.2, 72.5, 72.8, 73.2, 73.5, 74.6, 74.7, 75.2
(8×CH2Ph)], 72.5, 73.0, 73.3, 75.5, 76.3, 77.9,