reduced pressure and the residue was coevoporated with tolu-
ene (2 × 50 cm3). An analytical sample was purified by column
chromatography (30% (v/v) EtOAc in light petroleum) to give
as the major product furanoside 7a. Rf 0.53 (EtOAc–light pet-
roleum 75 : 25, v/v); δH (CDCl3) 7.28 (2H, d, J 8.3, Ar-H), 6.91
(2H, d, J 8.6, Ar-H), 4.87 (1H, s, H-1), 4.62 (1H, d, J 11.4,
CH2 (MPM)), 4.53 (1H, d, J 11.2, CH2 (MPM)), 4.43 (1H, d,
J 11.1, H-5a), 4.38 (1H, d, J 11.3, H-5b), 4.31 (1H, d, J 9.6,
H-5Јa), 4.25 (1H, d, J 4.9, H-3), 4.06 (1H, d, J 9.8, H-5Јb), 3.98
(1H, dd, J 2.5 and 4.7, H-2), 3.81 (3H, s, OCH3 (MPM)), 3.33
(3H, s, OCH3), 3.06 (3H, s, SO2CH3), 3.03 (3H, s, SO2CH3), 2.55
(1H, d, J 2.5, 2-OH); δC (CDCl3) 160.0, 130.1, 128.5 and 114.3
(Ar), 107.8 (C-1), 81.7 (C-4), 81.2 (C-3), 73.9 (C-2), 73.6 (CH2
(MPM)), 69.7 and 69.5 (C-5 and C-5Ј), 55.5 (OCH3), 55.4
(OCH3 (MPM)), 37.5 (SO2CH3), 37.4 (SO2CH3); MALDI-
HRMS: m/z 493.0811 ([M ϩ Na]ϩ, C17H26O11S2Naϩ calc.
493.0808). The minor product was tentatively assigned as 8a
presumably formed by deacetylation followed by base induced
intramolecular cyclization. The crude mixture of 7a and 8a was
therefore used in the next step without purification. Similarly,
deacetylation of the epimer 6b (5.05 g, 9.85 mmol) using
sat. methanolic ammonia (60 cm3) yielded two products. An
analytical sample was purified by column chromatography
(35% (v/v) EtOAc in light petroleum) to give the major product
7b as a white solid material. Rf 0.46 (EtOAc–light petroleum
75 : 25, v/v); δH (CDCl3) 7.28 (2H, d, J 8.5, Ar-H), 6.91 (2H, d,
J 8.5, Ar-H), 4.88 (1H, d, J 4.7, H-1), 4.70 (1H, d, J 11.3, CH2
(MPM)), 4.52 (1H, d, J 11.4, CH2 (MPM)), 4.44 (1H, d, J 10.8,
H-5a), 4.20 (1H, d, J 11.0, H-5b), 4.18 (1H, m, H-2), 4.14 (1H,
d, J 10.5, H-5Јa), 4.08 (1H, d, J 10.6, H-5Јb), 4.00 (1H, d, J 7.0,
H-3), 3.81 (3H, s, OCH3 (MPM)), 3.46 (3H, s, OCH3), 3.01 (3H,
s, SO2CH3), 3.00 (3H, s, SO2CH3), 2.88 (1H, d, J 11.2, 2-OH);
δC (CDCl3) 159.8, 130.2, 128.9 and 114.2 (Ar), 103.6 (C-1), 83.2
(C-4), 77.7 (C-3), 75.0 (C-2), 71.9 (CH2 (MPM)), 69.2 and 69.1
(C-5 and C-5Ј), 56.3 (OCH3), 55.4 (OCH3 (MPM)), 37.6
(SO2CH3), 37.4 (SO2CH3); MALDI-HRMS: m/z 493.0819
([M ϩ Na]ϩ, C17H26O11S2Naϩ calc. 493.0809).
Ar-H), 4.99 (1H, s, H-1), 4.61 (1H, d, J 11.7, CH2 (MPM)), 4.52
(1H, d, J 11.4, CH2 (MPM)), 4.48 (1H, d, J 11.9, H-5a), 4.41
(1H, d, J 11.6, H-5b), 4.18 (1H, s, H-2), 4.04 (1H, d, J 8.0, H-
5Јa), 3.92 (1H, d, J 8.8, H-5Јb), 3.91 (1H, s, H-3), 3.81 (3H, s,
OCH3 (MPM)), 3.47 (3H, s, OCH3), 3.05 (3H, s, SO2CH3);
δC (CDCl3) 159.5, 129.4, 128.8 and 113.9 (Ar), 104.2 (C-1), 86.2
(C-4), 79.2 (C-3), 76.9 (C-2), 72.1 (C-5Ј), 71.7 (CH2 (MPM)),
66.0 (C-5), 56.2 (OCH3), 55.2 (OCH3 (MPM)), 37.5 (SO2CH3);
MALDI-HRMS: m/z 397.0926 ([M ϩ Na]ϩ calc. C16H22O8-
SNaϩ 397.0927).
(1S,3RS,4S,7R)-1-Acetoxymethyl-3-methoxy-7-(p-methoxy-
benzyloxy)-2,5-dioxabicyclo[2.2.1]heptane (9). To a stirred solu-
tion of furanoside 8a (11.6 g, 31.0 mmol) in anhydrous dioxane
(45 cm3) was added 18-crown-6 (16.4 g, 62.0 mmol) and KOAc
(15.2 g, 154.9 mmol), and the mixture was heated under reflux
for 12 h. The reaction mixture was concentrated to dryness
under reduced pressure and the residue dissolved in CH2Cl2
(100 cm3). Washing was performed successively with sat. aq.
NaHCO3 (2 × 50 cm3) and brine (50 cm3). The separated
organic phase was dried (Na2SO4), filtered and evaporated to
dryness under reduced pressure. The residue was purified by
column chromatography (20% (v/v) EtOAc in light petroleum)
to afford furanoside 9a as a white solid material (9.65 g, 92%).
Rf 0.63 (EtOAc–light petroleum 50 : 50, v/v); δH (CDCl3) 7.26
(2H, d, J 7.9, Ar-H), 6.88 (2H, d, J 8.4, Ar-H), 4.80 (1H, s,
H-1), 4.59 (1H, d, J 11.6, CH2 (MPM)), 4.48 (1H, d, J 11.7,
CH2 (MPM)), 4.47 (1H, d, J 12.7, H-5a), 4.27 (1H, d, J 12.4,
H-5b), 4.09 (1H, s, H-2), 4.05 (1H, s, H-3), 3.99 (1H, d, J 7.4,
H-5Јa), 3.80 (3H, s, OCH3 (MPM)), 3.71 (1H, d, J 7.4, H-5Јb),
3.36 (3H, s, OCH3), 2.06 (3H, s, COCH3); δC (CDCl3) 170.4
(COCH3), 159.3, 129.4, 129.2 and 113.7 (Ar), 104.9 (C-1), 83.1
(C-4), 78.7 (C-2), 76.9 (C-3), 71.9 (CH2 (MPM)), 71.8 (C-5Ј),
60.9 (C-5), 55.2 and 55.1 (OCH3 and OCH3 (MPM)), 20.6
(COCH3); MALDI-HRMS: m/z 361.1245 ([M ϩ Na]ϩ, C17H22-
O7Naϩ calc. 361.1258). Similarly, reaction of furanoside 8b (646
mg, 1.73 mmol) with KOAc (880 mg, 8.97 mmol) in the pres-
ence of 18-crown-6 ether (940 mg, 3.56 mmol) in anhydrous
dioxane (3 cm3) followed by work-up and column chromato-
graphy (30% (v/v) EtOAc–light petroleum) afforded furanoside
9b as a white solid material (455 mg, 78%). Rf 0.29 (EtOAc–
light petroleum 50 : 50, v/v); δH (CDCl3) 7.26 (2H, d, J 9.0,
Ar-H), 6.88 (2H, d, J 8.3, Ar-H), 4.98 (1H, s, H-1), 4.61 (1H, d,
J 11.7, CH2 (MPM)), 4.49 (1H, d, J 11.7, CH2 (MPM)), 4.35
(1H, d, J 12.9, H-5a), 4.28 (1H, d, J 12.8, H-5b), 4.18 (1H, s,
H-2), 4.02 (1H, d, J 8.0, H-5Јa), 3.92 (1H, d, J 7.9, H-5Јb), 3.87
(1H, s, H-3), 3.80 (3H, s, OCH3 (MPM)), 3.48 (3H, s, OCH3),
2.05 (3H, s, COCH3); δC (CDCl3) 170.6 (COCH3), 159.6, 129.5,
129.3 and 113.9 (Ar), 104.3 (C-1), 86.6 (C-4), 79.5 (C-3), 77.1
(C-2), 72.6 (C-5Ј), 71.7 (CH2 (MPM)), 60.8 (C-5), 56.4 (OCH3),
55.4 (OCH3 (MPM)), 20.8 (COCH3); MALDI-HRMS: m/z
361.1253 ([M ϩ Na]ϩ, C17H22O7Naϩ calc. 361.1258).
(1S,3RS,4S,7R)-1-Methanesulfonyloxymethyl-3-methoxy-7-
(p-methoxybenzyloxy)-2,5-dioxabicyclo[2.2.1]heptane (8). The
crude mixture (∼23.0 g) obtained from methanolic ammonia
treatment of 6a was dissolved in anhydrous DMF (50 cm3) and
the resulting mixture was cooled to 0 ЊC. Sodium hydride (4.0 g,
60% suspension in mineral oil (w/w), 100 mmol) was added
slowly during 10 min and the mixture was stirred for 12 h at rt
whereupon ice-cold H2O (200 cm3) was carefully added. The
resulting mixture was extracted using EtOAc (3 × 100 cm3) and
the combined organic phase was washed successively with sat.
aq. NaHCO3 (2 × 100 cm3) and brine (50 cm3), dried (Na2SO4),
filtered and concentrated to dryness under reduced pressure.
The residue was purified by column chromatography (30% (v/v)
EtOAc in light petroleum) to give furanoside 8a as a white solid
material (11.6 g, 72% from 6a). Rf 0.35 (EtOAc–light petroleum
50 : 50, v/v); δH (CDCl3) 7.26 (2H, d, J 8.6, Ar-H), 6.89 (2H, d,
J 8.7, Ar-H), 4.81 (1H, s, H-1), 4.59 (1H, d, J 11.2, H-5a)
4.53–4.44 (3H, m, H-5b and CH2 (MPM)), 4.10 and 4.09 (1H
each, 2s, H-2 and H-3), 4.00 (1H, d, J 7.4, H-5Јa), 3.81 (3H, s,
OCH3 (MPM)), 3.69 (1H, d, J 7.4, H-5Јb), 3.37 (3H, s, OCH3),
3.05 (3H, s, SO2CH3); δC (CDCl3) 159.6, 129.5, 129.3 and 114.0
(Ar), 105.3 (C-1), 83.2 (C-4), 78.6 and 77.2 (C-2 and C-3), 72.1
(CH2 (MPM)), 71.8(C-5Ј), 66.3(C-5), 55.6 (OCH3), 55.4 (OCH3
(MPM)), 37.8 (SO2CH3); MALDI-HRMS: m/z 397.0928 ([M ϩ
Na]ϩ, C16H22O8SNaϩ calc. 397.0927). Similarly the crude mix-
ture (∼5.5 g) obtained from methanolic ammonia treatment of
6b was reacted with sodium hydride (1.0 g, 60% suspension in
mineral oil (w/w), 25 mmol)). After work-up, the residue was
purified by column chromatography (45% (v/v) EtOAc in light
petroleum) affording furanoside 8b as a white solid material
(2.54 g, 69% from 6b). Rf 0.24 (EtOAc–light petroleum 50 : 50,
v/v); δH (CDCl3) 7.27 (2H, d, J 8.6, Ar-H), 6.89 (2H, d, J 9.0,
(1R,3RS,4S,7R)-1-Hydroxymethyl-3-methoxy-7-(p-methoxy-
benzyloxy)-2,5-dioxabicyclo[2.2.1]heptane (10). A solution of
furanoside 9a (2.27 g, 6.71 mmol) in sat. methanolic ammonia
(55 cm3) was stirred for 12 h at rt. The reaction mixture was
evaporated to dryness under reduced pressure and coevapo-
rated with toluene (2 × 10 cm3). The residue was purified by
column chromatography (55% (v/v) EtOAc in light petroleum)
to give furanoside 10a as a white solid material (1.91 g, 96%). Rf
0.31 (EtOAc–light petroleum 50 : 50, v/v); δH (CDCl3) 7.28–
7.25 (2H, m, Ar-H), 6.89–6.86 (2H, m, Ar-H), 4.80 (1H, s, H-1),
4.59 (1H, d, J 11.3, CH2 (MPM)), 4.52 (1H, d, J 11.7, CH2
(MPM)), 4.09 (2H, s, H-2 and H-3), 3.97 (1H, d, J 7.6, H-5Јa),
3.86 (1H, s, H-5a), 3.84 (1H, s, H-5b), 3.79 (3H, s, OCH3
(MPM)), 3.64 (1H, d, J 7.3, H-5Јb), 3.37 (3H, s, OCH3), 2.14
(1H, dd, J 6.0 and 6.6, 5-OH); δC (CDCl3) 159.5, 129.8, 129.4
and 113.9 (Ar), 105.2 (C-1), 85.6 (C-4), 78.3 and 77.4 (C-2 and
C-3), 71.9 (CH2 (MPM)), 71.8 (C-5Ј), 58.8 (C-5), 55.5 and 55.3
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 8 0 – 8 9
85