I.D. Mackie et al. / Carbohydrate Research 337 (2002) 161–166
165
(1.00 g, 2.81 mmol), a,a-dimethoxytoluene (0.63 mL,
4.21 mmol), p-toluene–sulfonic acid (0.05 g) and anhyd
DMF (50 mL) were stirred at rt for 3 days. A second
portion of a,a-dimethoxytoluene (0.42 mL, 2.81 mmol)
was added and the mixture was heated to 50 °C under
reduced pressure (50 mbar) for 2 h. After addition of
triethylamine (3 mL), the reaction mixture was evapo-
rated. Column chromatography of the residue (10:1
EtOAc–MeOH) gave 2 as colourless crystals (0.782 g,
63%), mp 150–152 °C, lit. 151–152 °C (EtOH);12 [h]D20
−32° (c 1.2, MeOH), lit. [h]2D0 −37° (c 1.9, DMF).12
1H NMR (CD3OD): l 7.35–7.58 (m, 5 H, Ph), 5.63 (s,
1 H, CHPh), 4.61 (d, 1 H, J1%,2% 7.8 Hz, H-1%), 4.35 (dd,
1 H, J5%,6b% 3.7, J6a%,6b% 10.2 Hz, H-6b%), 4.25 (d, 1 H, J1,2
7.8 Hz, H-1), 3.90–3.96 (m, 1 H, H-6b), 3.88 (dd, 1 H,
J5%,6a% 3.9 Hz, H-6a%), 3.83 (dd, 1 H, J3,4 9.7, J4,5 9.7 Hz,
H-4), 3.60–3.75 (m, 2 H, H-5, H-3%), 3.50–3.57 (m, 5
H, H-5%, 1-OMe, H-3, H-4%), 3.30–3.50 (m, 2 H, H-6a,
H-2%) and 3.28 (dd, 1 H, J2,3 8.3 Hz, H-2).
CHCl3).13 1H NMR data (CDCl3): l 7.19–7.36 (m, 30
H, 6×Ph), 4.93 (d, 1 H, J 11.0 Hz, CH2Ph), 4.67–4.87
(m, 7 H, CH2Ph), 4.59 (d, 1 H, J 12.1 Hz, CH2Ph), 4.47
(d, 1 H, J1%,2% 7.2 Hz, H-1%), 4.40–4.46 (m, 3 H, CH2Ph),
4.27 (d, 1 H, J1,2 7.7 Hz, H-1), 3.96 (dd, 1 H, J3,4 9.1,
J4,5 9.1 Hz, H-4), 3.82 (dd, 1 H, J5,6b 4.2, J6a,6b 11.0 Hz,
H-6b), 3.70 (dd, 1 H, J5,6a 2.2, Hz, H-6a), 3.46–3.64 (m,
7 H, H-6a%, H-6b%, 1-OMe, H-4%, H-3), 3.29–3.41 (m, 4
H, H-2, H-5, H-3%, H-2%), 3.20–3.28 (m, 1 H, H-5%) and
2.86 (d, 1 H, J4%,OH 1.5 Hz, OH).
Methyl 2,3,6-tri-O-benzyl-4-O-methyl-i-D-glucopy-
ranosyl-(14)-2,3,6-tri-O-benzyl-i- -glucopyranoside
D
(5).—Sodium hydride (0.337 g, 14.1 mmol) was added
to a solution of 4 (6.22 g, 7.03 mmol) in dry THF (150
mL). The mixture was stirred under argon for 1 h.
Methyl iodide (2.19 mL, 35.1 mmol) was added, and
the mixture was stirred overnight at rt. The reaction
mixture was poured onto aq satd NH4Cl and extracted
with EtOAc (100 mL). The organic layer was dried over
MgSO4 and concentrated. Chromatography of the
crude product on silica gel (toluene7:1 toluene–
EtOAc) gave 5 as colourless syrup (5.99 g, 95%); [h]D20
Methyl 2,3-di-O-benzyl-4,6-O-benzylidene-i-
D-glu-
copyranosyl-(14)-2,3,6-tri-O-benzyl-i- -glucopy-
D
ranoside (3).—Sodium hydride (3.83 g, 160 mmol) was
added to a solution of 2 (7.10 g, 16.0 mmol) in anhyd
DMF (150 mL). The mixture was stirred under argon
for 1 h. Benzyl bromide (19.0 mL, 160 mmol) was
added and the mixture was stirred overnight at rt. The
solution was poured onto satd aq NH4Cl and extracted
with EtOAc. The combined organic layers were dried
over MgSO4 and evaporated. Chromatography (tolu-
ene7:1 toluene–EtOAc) of the crude product gave 3
as colourless crystals (9.95 g, 71%), mp 144–146 °C
(EtOH), lit. 143–145 °C (4:1 hexane–EtOAc);13 [h]D20
1
+23° (c 0.5, CHCl3). H NMR (CDCl3): l 7.16–7.35
(m, 30 H, 6×Ph), 5.03 (d, 1 H, J 11.5 Hz, CH2),
4.65–4.85 (m, 9 H, CH2), 4.58 (d, 1 H, J 12.1 Hz, CH2),
4.46 (d, 1 H, J1%,2% 7.1 Hz, H-1%), 4.43 (d, 1 H, J 11.5 Hz,
CH2), 4.27 (d, 1 H, J1,2 7.7 Hz, H-1), 3.99 (dd, 1 H, J3,4
9.3, J4,5 9.3 Hz, H-4), 3.81 (dd, 1 H, J5,6a 4.2, J6a,6b 11.0
Hz, H-6a), 3.64–3.72 (m, 2 H, H-6b, H-6a%), 3.49–3.60
(m, 5 H, H-3, 1-OMe, H-6b%), 3.47 (s, 3 H, 4%-OMe),
3.28–3.45 (m, 5 H, H-3%, H-2, H-5, H-4%, H-2%) and
3.15–3.20 (m, 1 H, H-5%). Anal. Calcd for C55H62O11:
C, 73.47; H, 6.95. Found: C, 73.21; H, 6.80.
+1° (c 0.9, CHCl3), lit. [h]2D0 +4° (c 2.1, CHCl3).13 1
H
NMR data (CDCl3): l 7.22–7.50 (m, 30 H, 6×Ph),
5.48 (s, 1 H, CHPh), 4.68–4.91 (m, 8 H, CH2Ph), 4.58
(d, 1 H, J 12.1 Hz, CH2Ph), 4.53 (d, 1 H, J1%,2% 7.7 Hz,
H-1%), 4.38 (d, 1 H, J 12.1 Hz, CH2Ph), 4.28 (d, 1 H,
J1,2 7.6 Hz, H-1), 3.82 (dd, 1 H, J5%,6b% 5.1, J6a%,6b% 10.6
Hz, H-6b%), 3.98 (dd, 1 H, J3,4 9.2, J4,5 9.2 Hz, H-4),
3.83 (dd, 1 H, J5,6b 3.7, J6a,6b 10.8 Hz, H-6b), 3.67 (dd,
1 H, J5,6a 1.2 Hz, H-6a), 3.30–3.61 (m, 10 H, H-3%,
H-4%, 1-OMe, H-3, H-6a%, H-2, H-2%, H-5) and 3.09–
3.18 (m, 1 H, H-5%).
Methyl 4-O-methyl-i-
D
-glucopyranosyl-(14)-i-D-
glucopyranoside (6).—A solution of 5 (5.90 g, 6.56
mmol) in dry MeOH (100 mL) was hydrogenated at rt
in the presence of 10% Pd–C (0.25 g) for 15 h at
atmospheric pressure. The catalyst was removed by
filtration, and the filtrate was concentrated to yield 6 as
colourless crystals (2.35 g, 97%); mp 196–198 °C
1
(MeOH); [h]2D0 −11° (c 0.4, water). H NMR (D2O): l
4.47 (d, 1 H, J1%,2% 7.9 Hz, H-1%), 4.39 (d, 1 H, J1,2 8.0
Hz, H-1), 3.98 (dd, 1 H, J5,6a 1.8, J6a,6b 12.3 Hz, H-6a),
3.90 (dd, 1 H, J5%,6a% 2.3 Hz, H-6a%), 3.89 (dd, 1 H, J5,6b
4.6 Hz, H-6b), 3.73 (dd, 1 H, J5%,6b% 5.3, J6a%,6b% 12.4 Hz,
H-6b%), 3.56–3.63 (m, 7 H, H-5, H-4, H-3, H-3%, 1-
OMe), 3.55 (s, 3 H, 4%-OMe), 3.47 (ddd, 1 H, J4%,5% 9.5
Hz, H-5%), 3.25–3.40 (m, 2 H, H-2%, H-2), 3.22 (dd, 1 H,
J3%,4% 9.5 Hz, H-4%); 13C NMR (D2O): l 103.87 (C-1),
103.27 (C-1%), 79.94 (C-4%), 79.42 (C-4), 75.96 (C-3%),
75.79 (C-5), 75.56 (C-5%), 75.11 (C-3), 73.97 (C-2%), 73.68
(C-2), 61.11 (C-6%), 60.83 (C-6, 4%-Me) and 58.02 (1-
Me). IR (KBr): 3440 (b), 2916 (s), 2883 (s), 1620 (w),
1452 (m), 1451 (m), 1363 (m), 1165 (s), 1107 (s), 1035
(s), 993 (s). Anal. Calcd for C14H26O11: C, 45.40; H,
7.08. Found: C, 45.34; H, 6.80.
Methyl 2,3,6-tri-O-benzyl-i-
D
-glucopyranosyl-(1
4)-2,3,6-tri-O-benzyl-i- -glucopyranoside (4).—A so-
D
lution of HCl in anhyd Et2O (2.5 M) was added
dropwise to a solution of 3 (4.72 g, 5.35 mmol) and
NaCNBH3 (3.36 g, 53.5 mmol) in dry THF (100 mL)
,
containing powdered 3 A molecular sieves, until the
evolution of gas ceased. The molecular sieves were
filtered off after 30 min, and EtOAc was added. The
mixture was extracted twice with satd NaHCO3 and
once with brine. The organic layer was dried over
MgSO4 and evaporated. Column chromatography (9:1
toluene–EtOAc) yielded a 4 as colourless syrup (3.63 g,
77%); [h]2D0 +8° (c 0.4, CHCl3), lit. [h]2D0 +7° (c 1.5,