W. Hakamata et al. / Carbohydrate Research 324 (2000) 107–115
113
according to Methods B and C. The product
was purified by column chromatography on
silica gel (4:1 hexane–EtOAc) to afford 15
(0.95 g, (74.6%), which was recrystallized from
EtOH: mp 133.5–134.0 °C; [h]D +76° (c 0.60,
H-6b), 5.15 (d, 1 H, J1,2 3.6 Hz, H-1), 5.27
(dd, 1 H, J2,3 10.2 Hz, H-2), 5.80 (dd, 1 H, J3,4
10.2 Hz, H-3), 7.35–8.11 (m, 15 H, aromatic
H); MS: 507 [MH+].
Methyl
2,3,6-tri-O-benzoyl-4-deoxy-h- -
D
1
CHCl3); H NMR (400 MHz, CDCl3): l 2.56
xylo-hexopyranoside (20).—To a solution of
18 (10.9 g, 21.5 mmol) in CH2Cl2 (300 mL)
was added 4-dimethylaminopyridine (7.89 g,
64.5 mmol) at rt, followed by dropwise addi-
tion of phenylchlorothionoformate [31] (3.6
mL, 25.8 mmol). The mixture was stirred for 4
days and the solvent was evaporated. The
product was purified by column chromatogra-
phy on silica gel (3:2 hexane–EtOAc). The
unstable thiocarbonyl derivative 19 (11.1 g,
17.2 mmol) was immediately dissolved in
toluene (700 mL), and then Bu3SnH (5.8 mL,
20.6 mmol) was added to the solution. After
refluxing the mixture overnight, the solvent
was evaporated and the product was purified
by column chromatography on silica gel (3:1
hexane–EtOAc) to afford 20 (7.95 g, 94.3%):
mp 115.5–117.0 °C; [h]D +132° (c 1.1,
(ddd, 1 H, J2,3eq =J3eq,4 4.0, J3ax,3eq 13.8 Hz,
H-3eq), 2.66 (ddd, 1 H, J2,3ax 12.4, J3ax,4 3.0
Hz, H-3ax), 4.41–4.53 (m, 3 H, H-5, H-6a,
and H-6b), 5.60 (ddd, 1 H, J1,2 3.6 Hz, H-2),
5.62 (ddd, 1 H, J4,5 5.2 Hz, H-4), 6.06 (d, 1 H,
H-1), 7.19–8.15 (m, 19 H, aromatic H); MS:
598 [MH+].
p-Nitrophenyl 3-deoxy-h- -xylo-hexopyran-
D
oside (16).—Compound 16 was prepared from
15 (0.67 g, 1.13 mmol) according to Method
E. The product was purified by column chro-
matography on silica gel (8:1 CH2Cl2–MeOH)
to afford 16 (0.22 g, 67.4%), which was recrys-
tallized from hot EtOH: mp 162.0–163.5 °C,
lit. 163.5–164.5 °C [27]; [h]D +221° (c 0.56,
1
MeOH), lit. +219° [27]; H NMR (400 MHz,
D2O): l 2.13 (ddd, 1 H, J2,3eq=J3eq,4 4.4,
J3ax,3eq 13.6 Hz, H-3eq), 2.23 (ddd, 1 H, J2,3ax
13.0, J3ax,4 3.0 Hz, H-3ax), 3.65–3.67 (m, 2 H,
H-6a and H-6b), 3.89 (ddd, 1 H, J4,5 1.1, J5,6a
5.5, J5,6b 6.6 Hz, H-5), 4.13 (m, 1 H, H-4), 4.28
(ddd, 1 H, J1,2 3.6 Hz, H-2), 5.79 (d, 1 H,
H-1), 7.33 (d, 2 H, J 9.2 Hz, aromatic H), 8.28
(d, 2 H, aromatic H); MS: 286 [MH+]: Anal.
Calcd for C12H15O7: C, 50.53; H, 5.30; N,
4.91. Found: C, 50.37; H, 5.35; N, 4.91.
1
CHCl3); H NMR (400 MHz, CDCl3): l 1.90
(ddd, 1 H, J3,4ax=J4ax,5 =J4ax,4eq 11.9 Hz, H-
4ax), 2.48 (ddd, 1 H, J3,4eq 5.4, J4eq,5 2.2 Hz,
H-4eq), 3.46 (s, 3 H, ꢀOCH3), 4.36–4.50 (m, 3
H, H-5, H-6a and H-6b), 5.18 (d, 1 H, J1,2 3.6
Hz, H-1), 5.32 (dd, 1 H, J2,3 10.0 Hz, H-2),
5.79 (ddd, 1 H, H-3), 7.36–8.10 (m, 15 H,
aromatic H); MS: 419 [MH+].
p-Nitrophenyl 2,3,6-tri-O-benzoyl-4-deoxy-
Methyl 2,3,6-tri-O-benzoyl-h- -glucopyran-
D
h- -xylo-hexopyranoside (22).—Compound
D
oside (18).—Compound 17 (7.65 g, 39.4
mmol) and bistributyltin oxide [(Bu3Sn)2O, 25
mL, 59.1 mmol] were dissolved in toluene (750
mL). After refluxing the mixture overnight,
the solvent was cooled to rt, and BzCl (20.6
mL, 177.4 mmol) was added. The mixture was
stirred for 4 days at rt and the solvent was
evaporated. The residue was dissolved in
MeCN (400 mL) and washed with hexane
(2×200 mL) to remove the remaining
(Bu3Sn)2O. After evaporation of the solvent,
the product was purified by column chro-
matography on silica gel (3:1 hexane–EtOAc)
to afford 18 (10.9 g, 54.5%): [h]D +140° (c
21 was prepared from 20 (7.95 g, 16.2 mmol)
according to Method B. The residue was
purified by column chromatography on silica
gel (4:1 hexane–EtOAc) to afford 21 (6.96 g,
82.8%). Compound 22 was prepared from 21
(1.44 g, 2.78 mmol) according to Method C.
The product was purified by column chro-
matography on silica gel (4:1 hexane–EtOAc)
to afford 22 (1.17 g, 70.4%), which was recrys-
tallized from hot EtOH: mp 173.0–176.0 °C;
1
[h]D +148° (c 1.0, CHCl3); H NMR (400
MHz, CDCl3): l 1.99 (ddd, 1 H, J3,4ax
=
J
4ax,5=J4ax,4eq 12.0 Hz, H-4ax), 2.55 (ddd, 1
H, J3,4eq 5.0, J4eq,5 5.2 Hz, H-4eq), 4.36–4.47
(m, 3 H, H-5, H-6a and H-6b), 5.50 (dd, 1 H,
J1,2 3.6, J2,3 10.4 Hz, H-2), 5.99 (ddd, 1 H,
H-3), 6.06 (d, 1 H, H-1), 7.39–8.08 (m, 15 H,
aromatic H); MS: 598 [MH+].
1
1.0, CHCl3); H NMR (400 MHz, CDCl3): l
3.46 (s, 3 H, ꢀOCH3), 3.89 (m, 1 H, H-4), 4.12
(ddd, 1 H, J5,6a 2.2, J5,6b 4.6 Hz, H-5), 4.64
(dd, 1 H, J6a,6b 12.2 Hz, H-6a), 4.79 (dd, 1 H,