S.E. Soliman et al. / Carbohydrate Research 338 (2003) 2337ꢀ
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2339
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bar, glycosyl trichloroacetimidate, and powdered 4 A
activated molecular sieves. After these additions, the
reactor was closed at the neck (rubber septum) and dried
The second fraction from the chromatography com-
pound 4 was isolated by evaporation of the solvent
under diminished pressure and the residual syrup
by keeping the system under vacuum for 3ꢀ
dry CH2Cl2 is injected with a dry syringe and the
mixture was stirred for 15 min at room temperature
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4 h. Next,
crystallized from EtOAcꢀ
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petroleum ether giving 4 (232
mg; 54%); mp 220 8C. H NMR (400 MHz, CDCl3): d
7.90ꢀ7.84, 7.78ꢀ7.74 (2 m, 4 H, C6H4ꢁ); 7.46ꢀ7.42,
7.40ꢀ7.36 (2 m, 5 H, PhꢁH); 5.70ꢀ5.59 (m, 1 H, ꢁ
CH ꢀ); 5.52 (s, 1 H, PhꢁCH); 5.19 (d, 1 H, J1,2 8.4
Hz, H-1b); 5.14ꢀ5.04 (4 q, 2 H, ꢀCH2); 5.00 (t, 1 H,
1
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(rt) and then cooled to ꢁ
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30 8C. Trimethylsilyl triflate
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was added and the mixture was stirred below ꢁ
for 1 h and then allowed to warm up gradually to rt. The
mixture was kept overnight at rt with stirring, at which
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30 8C
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J4?,5? 9.6 Hz, J3?,4? 10.0 Hz, H-4?); 4.99 (t, 1 H, J3?,4? 10.8
Hz, J2?,3? 9.2 Hz, H-3?); 4.79 (t, 1 H, J2?,3? 8.4 Hz, J1?,2? 8.0
Hz, H-2?); 4.74 (dd, 1 H, J 9.2, 8.4 Hz, H-3); 4.60 (d, 1
time TLC (3:7:10 EtOAcꢀ
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petroleum etherꢀtoluene)
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showed disappearance of the starting material and two
new spots (a high mobility spot; above the donor and
low mobility spot; below the donor and above the
acceptor). A few drops of Et3N was added to quench the
reaction, and the solid was filtered off over a bed of
Celite and washed with CH2Cl2. The combined filtrate
and washings were evaporated to dryness under dimin-
ished pressure. The resulting residue was subjected to
column chromatography on silica gel using 1:3:10
H, J1?,2? 8.0 Hz, H-1?b); 4.42ꢀ
6b); 4.24 and 4.01 (2 q, 2 H, ꢁ
(m, 2 H, H-4 and H-6a); 3.67ꢀ
(s, 3 H, COOCH3); 3.55 (d, 1 H, J4?,5? 9.6 Hz, H-5?); and
1.92, 1.87, 1.46 (3 s, 9 H, 3ꢃ
OCOCH3); 13C NMR (100
MHz, CDCl3): d 170.13, 169.38, 168.71 (3 C, 3ꢃ
OCOCH3); 166.87 (COOCH3); 137.00ꢀ126.22 (aro-
matic carbons and ꢁCHꢀ); 117.94 (ꢀCH2); 101.89
(PhꢁCHꢁ); 100.04 (C-1?); 97.89 (C-1); 81.30 (C-4);
76.14 (C-3); 72.49 (C-3?); 72.20 (C-5?); 71.65 (C-2?);
70.31ꢀ96.07 (3 C, C-6a,b and C-4?); 66.63 (C-5); 55.43
(C-2); 53.00 (COOCH3); 20.93, 20.89, 20.30 (3 C, 3ꢃ
OCOCH3). MS (m/z)ꢄ 771.9
753.6 (Mꢂ), (m/z)ꢄ
(Mꢂ 1.5 H2O:
H2O)ꢂ. Anal. Calcd for C37H39NO16×
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4.33 (m, 2 H, H-2 and H-
OCH2ꢁCHꢀ); 3.91ꢀ3.83
3.61 (m, 1 H, H-5); 3.57
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EtOAcꢀ
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petroleum etherꢀ/toluene and then 3:7:10 as
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the eluent afforded a fast-moving fraction as a result
of transesterification of the acceptor. In the present
work, the proportions of reagents, with respect to
glycosyl acceptor were; trichloroacetimidate donor, 1.5
mol; trimethylsilyl triflate, 0.49 mol; CH2Cl2, 12 mL/g
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and 4 A molecular sieves 2 g/g.
C, 56.92; H, 5.42; N, 1.79. Found: C, 56.69; H, 5.17; N,
1.75.
1.3.1. Allyl
pyranosyluronate)-(10
phthalimido-b- -glucopyranoside (4). Compound 2 was
prepared as described by El-Sokkary and co-workers;7
1H NMR (400 MHz, CDCl3): d 7.90ꢀ
7.84, 7.76ꢀ7.72 (2
m, 4 H, C6H4ꢁ); 7.48ꢀ7.44, 7.38ꢀ7.34 (2 m, 5 H, Phꢁ
H); 5.75ꢀ5.65 (m, 1 H, ꢁCH ꢀ); 5.55 (s, 1 H, PhꢁCH);
5.48 (d, 1 H, J1,2 8 Hz, H-1), 5.17ꢀ5.05 (4 q, 2 H, ꢀCH2);
4.63 (dd, 1 H, J 8.8, 9.2 Hz, H-3); 4.42 (q, 1 H, J 4.8,
10.8 Hz, H-6a); 4.36ꢀ4.26 (m, 2 H, H-6b and ꢁOCHHꢁ
CHꢀ); 4.08ꢀ4.02 (m, 1 H, ꢁOCHH ꢁCHꢀ); 3.86 (t, 1 H,
J 10.0, 10.0 Hz, H-4); 3.79 (t, 1 H, J2,3 9.6 Hz, J1,2 8.4
Hz, H-2); 3.77ꢀ3.70 (m, 1 H, H-5). A mixture of 2 (250
(methyl
2,3,4-tri-O-acetyl-b-
D-gluco-
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3)-4,6-O-benzylidene-2-deoxy-2-
1.3.2. Benzyl
pyranosyl uronate)-(10
phthalimido-b- -glucopyranoside (5). Compound 3 was
prepared as described by Lemieux and co-workers;8 1
NMR (400 MHz, CDCl3): d 7.84ꢀ7.71 (m, 4 H,
C6H4ꢁ); 7.48ꢀ7.44, 7.38ꢀ7.34 (2 m, 5 H, PhꢁH);
7.10ꢀ7.00 (m, 5 H, C6H5ꢁCH2); 5.55 (s, 1 H, Phꢁ
CH); 5.44 (d, 1 H, J1.2 8.4 Hz, H-1); 4.85ꢀ4.53 (AB, 2
H, JAB 12.0 Hz, PhꢁCH2); 4.66ꢀ4.57 (m, 1 H, H-3); 4.44
(q, 1 H, J 4.4, 10.4 Hz, H-6a); 4.34 (dd, 1 H, J1,2 8.4 Hz,
J2.3 10.4 Hz, H-2); 3.92ꢀ3.72 (m, 3 H, H-4, H-5 and H-
(methyl
2,3,4-tri-O-acetyl-b-
3)-4,6-O-benzylidene-2-deoxy-2-
D-gluco-
D
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H
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6b); 2.78 (bs, 1 H, OH-3). A mixture of 3 (250 mg, 0.51
mmol), imidate 1 (370 mg, 0.77 mmol) was subjected to
the procedure for b-glycosidic coupling. The resulting
residue was subjected to column chromatography on
mg, 0.57 mmol) and imidate 1 (410 mg, 0.86 mmol) were
subjected to the procedure for b-glycosidic coupling just
described. The resulting residue was subjected to column
chromatography of silica gel using 1:3:10 EtOAcꢀ
petroleum etherꢀtoluene, then 3:7:10 as the eluent
afforded a fast-moving fraction; allyl 3-O-acetyl-4,6-
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silica gel using 1:3:10 EtOAcꢀ
then 3:7:10 as eluent afforded a fast-moving fraction,
benzyl 3-O-acetyl-4,6-O-benzylidene-2-deoxy-2-phthali-
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petroleum etherꢀtoluene,
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O-benzylidene-2-deoxy-2-phthalimido-b-
D-glucopyra-
noside (6);16 as a result of transesterification of the
acceptor, which was isolated and crystallized from
mido-b-
ification of the acceptor, which was isolated and
crystallized from EtOAcꢀpetroleum ether to yield 65
D-glucopyranoside (7); as a result of transester-
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1
EtOAcꢀ
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petroleum ether to give 54 mg of 4, mp
mg, mp 172 8C. The H NMR (400 MHz, CDCl3) was
similar to that of 3 except for the downfield shift of H-3
to d 5.88 (dd, 1 H, J 10.0, 9.2 Hz), loss of the OH signal,
and appearance of OCOCH3 at d 1.89 (s, 3 H). MS (m/
1
156 8C. The H NMR (400 MHz, CDCl3) was similar
to that of 2 excepts for the downfield shift of H-3 to d
5.89 (dd, 1 H, J 8.8, 9.2 Hz), loss of the OH signal and
appearance of OCOCH3 at d 1.90 (s, 3 H).
z)ꢄ
529.2 (Mꢂ).
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