A.E. Salinas / Carbohydrate Research 20 (1999) 34–46
43
Chromatographic purification on a dry-
column of alumina with 17:3 hexane–EtOAc
as the eluent gave 10 (2.99 g, 72%), which
crystallized from 1:1 Et2O–ligroin: mp 148–
filtrate evaporated to dryness. The amorphous
residue crystallized (501 mg, 95%) from
toluene; examination by TLC on silica gel
(solvent C) showed two spots having Rf 0.44
and 0.38. The relative intensities of the C-1
resonance signals in the 13C NMR spectrum of
the product revealed that it was a 7:3 mixture
of a and b anomers. Four recrystallizations
from 1:1 Et2O–ligroin gave 15, mp 165–
166 °C; [h]D+141.3° (c 0.5, CHCl3); Rf 0.44
1
149 °C (d); [h]D+36.7° (c 0.5, CHCl3); for H
13
and C NMR data see Tables 2 and 3. Anal.
Calcd for C39H37NO9: C, 71.00; H, 5.04; N,
2.12. Found: C, 70.97; H, 5.33; N, 2.01.
Preparation of 2,3,4,6-tetra-O-benzoyl-h- -
D
glucopyranose (17).—Compound 10 (2.4 g,
3.62 mmol) was suspended in 2:1 acetone–wa-
ter (80 mL) and Amberlite IR-120 (H+) resin
(10 g) was added. The mixture was stirred at
50 °C for 1 h and then at rt for 24 h. The
suspension was filtered and the filtrate evapo-
rated to dryness. The amorphous residue crys-
tallized (2.1 g, 97%) from 1:1 Et2O–ligroin;
examination by TLC on silica gel (solvent B)
showed two spots having Rf 0.40 and 0.33.
1
(silica gel, solvent C); H NMR data: l 5.66
(d, J1,2 3.5 Hz, H-1), 5.27 (dd, J2,3 10.1 Hz,
H-2), 5.89 (t, J3,4 9.7 Hz, H-3), 3.91 (m, J4,5
9.9, J4,OH 4.3 Hz, H-4; triplet on deuteration),
4.39 (m, H-5), 4.77 (dd, J5,6 3.7, J6,6% −12.1
Hz, H-6), 4.63 (dd, J5,6% 1.9 Hz, H-6%), 7.25–
8.09 (15 H, Ph), 3.53 and 3.80 (2 bs, 2 OH,
disappeared on deuteration); 13C NMR data:
l 90.57 (C-1), 71.76 (C-2), 73.46 (C-3), 69.63
(C-4), 70.23 (C-5), 63.43 (C-6), 128.40–133.36
(Ph), 165.96, 167.02, 167.35 (3 COPh). Anal.
Calcd for C27H24O9: C, 65.85; H, 4.91. Found:
C, 66.08; H, 5.15.
1
Integration of the H NMR spectrum in the
region of the H-3 resonance signals revealed
that the product was a 4:1 mixture of a and b
anomers. Recrystallization from ligroin gave
17 (1.38 g, 64%): mp 118–120 °C, lit 117–
120 °C [9]; [h]D +74.9° (c 0.5, CHCl3), lit +
N-(4-O-Acetyl-2,3,6-tri-O-benzoyl-i-
copyranosyl)piperidine (11).—Compound
D
-glu-
8
1
(300 mg, 0.54 mmol) was dissolved in pyridine
(0.6 mL) and treated with Ac2O (0.3 mL, 3.18
mmol) at 0 °C. The solution was kept for 3
days in a refrigerator and then evaporated in
vacuo over H2SO4 and KOH. The resulting
crystalline residue was recrystallized from
MeOH to give 11 (194 mg, 60%): mp 181–
72.4° [9]; Rf 0.40 (silica gel, solvent B); H
NMR data: l 5.72 (d, J1,2 3.5 Hz, H-1), 5.30
(dd, J2,3 10.2 Hz, H-2), 6.28 (t, J3,4 9.9 Hz,
H-3), 5.72 (t, J4,5 9.8 Hz, H-4), 4.69 (m, H-5),
4.48 (dd, J5,6 4.5, J6,6% −12.1 Hz, H-6), 4.63
(dd, J5,6% 3.1 Hz, H-6%), 7.25–8.08 (20 H, Ph),
3.90 (bs, OH, disappeared on deuteration); 13C
NMR data: l 90.53 (C-1), 72.44 (C-2), 70.44
(C-3), 69.69 (C-4), 67.76 (C-5), 63.03 (C-6),
128.38-133.38 (Ph), 165.25, 165.89 (×2),
166.37 (4 COPh).
1
182 °C (d); [h]D +95.1° (c 0.5, CHCl3); for H
13
and C NMR data see Tables 2 and 3. Anal.
Calcd for C34H35NO9: C, 67.89; H, 5.82; N,
2.33. Found: C, 67.69; H, 6.00; N, 2.50.
N-(2,3,4,6-Tetra-O-benzoyl-i-
D
-glucopyran-
Reaction of 17 with piperidine. Adduct of
osyl)piperidine (10).—A solution of 8 (3.5 g,
6.26 mmol) in pyridine (14 mL) was cooled to
0 °C and benzoyl chloride (2.1 mL, 18.09
mmol) was slowly added. The mixture was
kept for 3 days in a refrigerator and then
poured into ice-cold 5% aq NaHCO3 (70 mL).
After being kept for 1 h with occasional shak-
ing until evolution of gas ceased, the mixture
was extracted with CHCl3 (3×70 mL). The
organic extract was washed with water (2×70
mL), dried (Na2SO4), and evaporated to a
syrup that failed to crystallize. Examination
by TLC (alumina, solvent A), revealed the
presence of a major component, Rf 0.70.
2,3,4,6-tetra-O-benzoyl- -glucopyranose and
D
piperidine.—Compound 17 (596 mg, 1 mmol)
was suspended in dry Et2O (10 mL) and pip-
eridine (0.6 mL, 6 mmol) was added. The
resulting solution was kept at rt; after a few
minutes crystallization began. The reaction
mixture was cooled to 0 °C and the crystals
deposited were filtered off (595 mg, 87.4%):
mp 101–103 °C (d); [h]D +56.7° (c 0.5,
1
CHCl3). The H NMR spectrum revealed that
the product was a 1:1 adduct of 2,3,4,6-tetra-
O-benzoyl- -glucopyranose and piperidine;
D
integration of the H-3 signals showed that the
tetrabenzoate was present in the adduct as a