Synthetic study on a novel Asn-linked core structure: Synthesis of a pentasaccharide α-D-Man-(1→3)-[α-D-Man-(1→6)]-β-D-Man-(1→4)-[β-D- GlcNAc-(1→6)]-β-D-GlcNAc→OMp1

Article abstract of DOI:10.1016/S0008-6215(98)00031-7

Synthesis of a pentasaccharide α-D-Man-(1→3)-[α-D-Man-(1→6)]-β-D- Man-(1→4)-[β-D-Glc NAc(1→6)]-β-D-GlcNAc→OMp (2) is described. A comparison between the ¹H NMR data of 2 and those of a novel Asn-linked core structure 1 containing a new GlcNAc r

Full text of DOI:10.1016/S0008-6215(98)00031-7

Carbohydrate Research 306 (1998) 539±544
Synthetic study on a novel Asn-linked core
structure: synthesis of a pentasaccharide ꢀ-d-
Man-(1!3)-[ꢀ-d-Man-(1!6)]-ꢁ-d-Man-(1!4)-
[ꢁ-d-GlcNAc-(1!6)]-ꢁ-d-GlcNAc!OMp1
Zhong-Wu Guoa, Yukishige Itoa, Yoshiaki Nakaharaa,*,
Tomoya Ogawaa,b,
*
a The InstituteofPhysicalandChemicalResearch (RIKEN), 2-1Hirosawa, Wako-shi, Saitama, 351-01
Japan
b Graduate School of Agriculture andLife Sciences, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, 113
Japan
Received 27 October 1997; accepted 16 January 1997
Abstract
Synthesis of a pentasaccharide ꢀ-d-Man-(1!3)-[ꢀ-d-Man-(1!6)]-ꢁ-d-Man-(1!4)-[ꢁ-d-Glc
1
NAc(1!6)]-ꢁ-d-GlcNAc!OMp (2) is described. A comparison between the H NMR data of 2
and those of a novel Asn-linked core structure 1 containing a new GlcNAc residue suggests an ꢀ-
d-con®guration for the new linkage. # 1998 Elsevier Science Ltd. All rights reserved
Keywords: ꢀ-d-Man-(1!3)-[ꢀ-d-Man-(1!6)]-ꢁ-d-Man-(1!4)-[ꢁ-d-GlcNAc(1!6)]-ꢁ-d-GlcNAc!OMp; N-
Linked core structure
1. Introduction
c!Asn, ꢀ-d-Man-(1!3)-[ꢀ-d-Man-(1!6)]-ꢁ-d-
Man-(1!4)-ꢁ-d-GlcNAc-(1!4)-[ꢀ-l-Fuc (1!6)]-
ꢁ-d-GlcNAc!Asn, ꢀ-d-Man-(1!3)-[ꢁ-d-GlcNAc-
(1!4)]-[ꢀ-d-Man-(1!6)]-ꢁ-d-Man-(1!4)-ꢁ-d-
GlcNAc-(1!4)-ꢁ-d-GlcNAc!Asn and ꢀ-d-Man-
(1!3)-[ꢁ-d-GlcNAc-(1!4)]-[ꢀ-d-Man-(1!6)]-ꢁ-
d-Man-(1!4)-ꢁ-d-GlcNAc-(1!4)-[ꢀ-l-Fuc (1!6)]-
ꢁ-d-GlcNAc!Asn. However, Stanley et al. [3]
have recently isolated a novel N-linked core struc-
ture 1 with an additional GlcNAc attached to the
core GlcNAc from Chinese hamster ovary (CHO)
cell±LEC18. It was suggested that the new GlcNAc
residue markedly alters the conformation of rela-
ted oligosaccharides and thus causes the high
Most cell-surface proteins and many secretory
proteins are N-glycoproteins [1], and their N-
linked oligosaccharides play important biological
roles [2]. Despite the fact that a huge number of
di€erent N-linked oligosaccharide structures have
been disclosed, only four types of N-linked core
structures have been described in mammalian cells
before, namely: ꢀ-d-Man-(1!3)-[ꢀ-d-Man-(1!6)]-
ꢁ-d-Man-(1!4)-ꢁ-d-GlcNAc-(1!4)-ꢁ-d-GlcNA
* Corresponding authors.
1
Mp=p-meth
0008-6215/98/$19.00 # 1998 Elsevier Science Ltd. All rights reserved
PII S0008-6215(98)00031-7

540
Z.-W. Guo et al./Carbohydrate Research 306 (1998) 539±544
resistance of LEC18 cell to both pea lectin (PSA)
and Lens culinaris agglutinin (LCA). Nevertheless,
because in the 1H NMR spectrum of 1, the
anomeric proton of the new GlcNAc residue is at
rather low ®eld (ꢂ:5.21) and has a coupling con-
stant of 5.5 Hz that is an intermediate value
between the typical ones of ꢀ- and ꢁ-linked resi-
dues (3±4 Hz and 6.5±8.0 Hz, respectively), the
con®guration of the new linkage was therefore not
determined. Our present work is to synthesize a
part-structure 2 of the ꢁ-isomer of the novel core
structure and to compare the spectroscopic prop-
erties of 2 to those of the natural structure 1.
substantial amount of glycosyl acceptor 5 (35%)
was still recovered after overnight reaction. Com-
pound 7 was deallylated using an iridium complex
as catalyst [6]. Reaction of the resulting product 8
with 9 was stereoselectively promoted by silver tri-
¯uoromethanesulfonate to a€ord pentasaccharide
10 (84%). Dephthaloylation of 10 with ethylene-
diamine in n-butanol [7], followed by acetylation of
the resulting product in acetic anhydride and
methanol, was subsequently carried out in one pot
to produce 11 in 74% yield. Reductive debenzyla-
tion of 11 in the presence of Pd(OH)2 under a
hydrogen atmosphere ®nally gave the desired pro-
duct 2, which has shown satisfactory MS and
NMR results.
1
2. Results and discussion
As it is clearly shown in the H NMR spec-
trum of 2, the anomeric proton signal of GlcNAc-
ꢁ-(1!6) is at ꢂ 4.55 with a coupling constant of
8.3 Hz. These data are quite similar to those of a
typical ꢁ-linked GlcNAc (ꢂ: 4.60, J 8.0 Hz) observed
in all N-glycoproteins or N-glycopeptides. Our
observation of the di€erent coupling constants as
well as the 0.7 ppm chemical shift di€erence
between the anomeric protons for (1!6)-linked
GlcNAc in the natural product 1 (ꢂ: 5.21) and in
synthetic part-structure 2, together with the repor-
ted observation that the new (1!6)-linked GlcNAc
was not accessible to ꢁ-hexosaminidase [3], sug-
gested an ꢀ-d-con®guration for the novel GlcNAc
residue.
First of all, four properly protected and acti-
vated monosaccharides 3, 4, 6, and 9 were prepared
according to the reported methods [4]. Then, as
shown in Scheme 1, reaction of 3 and 4 at room
temperature, promoted by AgOTf, gave 5 (71%) as
the only product. In order to prepare compound 7
containing a ꢁ-mannosyl linkage, we employed a
reaction using monosaccharide 6 as the mannosyl
donor, disaccharide 5 as glycosyl acceptor, and sil-
ver alumina±silicate as promoter [5]. To the best of
our knowledge, this is the ®rst example trying to
introduce a ꢁ-mannosyl residue to the C-4 hy-
droxyl group of GlcNAc carrying a glycosyl residue
at C-6 by means of silver silicate promotion. Herein,
compound 7 and its ꢀ-isomer were obtained in
1.0:1.4 ratio and 53% yield. It is noteworthy that
the stereoselectivity for ꢁ-isomer was lower in this
reaction than those in reactions between 6 and
simple GlcNAc acceptors (ꢁ:ꢀ=1.2±1.4:1 [4]), and,
in addition, the reaction was slower and less e-
cient. Therefore, even when a large excess of gly-
cosyl donor 6 (3.5 equiv) was employed, a
3. Experimental
General methods.ÐOptical rotations were mea-
sured at 23‹2 ꢀC with a Jasco DIP 370 polari-
1
meter. H NMR spectra were recorded with a Jeol
EX 270 or a Jeol ꢀ600 spectrometer for solutions
in CDCl3 with TMS as the internal standard

Z.-W. Guo et al./Carbohydrate Research 306 (1998) 539±544
541
Scheme 1.
unless otherwise indicated. 1H and 13C signals were
assigned according to their 1D spectra and 2D
formed with Silica Gel 60 (E. Merck). Molecular
sieves (MS) were purchased from Nakarai Chemi-
cal Co. and were activated at 180 ꢀC under vacuum
immediately prior to use. All reactions except
hydrogenations were performed in anhydrous sol-
vent under a dry N2 atmosphere.
1
1H±1H or H±13C COSY spectra. Analytical TLCs
and preparative TLCs were performed on pre-
coated Silica Gel 60 F254 glass plates (E. Merck).
Silica gel column chromatography (CC) was per-

542
Z.-W. Guo et al./Carbohydrate Research 306 (1998) 539±544
p-Methoxyphenyl 3,4,6-tri-O-acetyl-2-deoxy-2-
each, 2 CH2=CH ), 5.69 (dd, 1 H, J3,4 8.8 Hz, J2,3
10.2 Hz, H-32 ), 5.64 (d, 1 H, 0 J1,2 8.3 Hz, H-11),
0
phthalimido-b-d-glucopyranosyl-(1!6)-3-O-benzyl-
2-deoxy-2-phthalimido-b-d-glucopyranoside (5).Ð
To a stirred mixture of 4 (447 mg, 0.85 mmol),
AgOTf (400 mg, 1.56 mmol) and 4A MS (1.5 g) in
dry CH2Cl2 (8 mL) was added a solution of 3
(551 mg, 1.11 mmol) in CH2Cl2 (5 mL) at 48 ꢀC.
The mixture was gradually warmed up to room
temperature and stirred overnight. It was ®ltered
through a Celite pad, and the ®ltrate was con-
centrated in vacuo followed by puri®cation by
silica gel CC (2.5:1 toluene±EtOAc) to give 5
(560 mg, 71%) as a white solid and recovered 4
5.49 (d, 1 H, J1,2 8.8 Hz, H-12 ), 5.38 (m, 1 H, Jt
17.1 Hz, CH2=), 5.23±5.15 (m, 2 H, CH2=), 5.15
0
(dd, 1 H, J4,5 10.5 Hz, H-42 ), 5.04 (m, 1 H, Jc
11.0 Hz, CH2=), 4.94±4.81 (m, 4 H, H-Bn), 4.57
(d, 1 H, J 10.9 Hz, H-Bn), 4.50 (s, 1 H, H-12), 4.41
0
(d, 1 H, J 12.9 Hz, H-Bn), 4.32 (dd, 1 H, H-22 ),
0
4.30±4.26 (m, 3 H, H-31, H-21, H-62 ), 4.23 (m, 1 H,
J 12.7, 5.4, 2.0 Hz, Hꢀ-All), 4.12 (m, 1 H, J 12.7,
0
0
4.9, 1.5 Hz, Hꢀ-All), 4.07 (dd, 1 H, J5,6 2.4 Hz, J6,6
0
12.7 Hz, H-602 ), 4.02±3.86 (m, 4 H, 2 Hꢀ-All, H-22,
H-61), 3.83±3.75 (m, 3 H, H-601, H-41, H-42), 3.74
1
0
(124 mg). 5: Rf 0.36 (1.6:1.0 toluene±EtOAc); H
(s, 3 H, OMe), 3.69 (dd, 1 H, J5,6 1.6 Hz, J6,6
NMR (270 MHz): ꢂ 7.88±7.66 (m, 8 H, H-aroma-
ticPhth), 7.02±6.97 (m, 5 H, H-aromaticBn), 6.80±
6.71 (m, 4 H, H-aromaticMp), 5.72 (dd, 1 H, J3,4
9.0 Hz, J2,3 10.4 Hz, H-32), 5.64 (d, 1 H, J1,2 7.6 Hz,
H-11), 5.54 (d, 1 H, J1,2 8.6 Hz, H-12), 5.15 (dd, 1
H, J4,5 10.1 Hz, H-42), 4.64, 4.48 (2 d, 1 H each, J
12.1 Hz, H-Bn), 4.35 (dd, 1 H, H-22), 4.30±4.23 (m,
11.2 Hz, H-62), 3.63 (m, 1 H, H-51), 3.50 (dd, 1 H,
0
J5,6 5.6 Hz, H-6 2), 3.43 (dd, 1 H, J3,4 9.8 Hz, J2,3
0
0
2.9 Hz, H-32), 3.40 (m, 1 H, H-52 ), 3.29 (m, 1 H, J
9.8, 5.4, 1.5 Hz, H-52), 2.04, 2.02, 1.84 (3 s, 3 H
each, 3 Ac); 13C NMR: ꢂ 101.03 (C-12), 97.40 (C-
0
12 ), 96.46 (C-11), 82.46 (C-32), 79.43 (C-41), 77.01
(C-31), 75.90 (C-52), 75.08 (C-22), 74.95 (Cꢀ-Bn),
74.56 (C-42), 74.43 (Cꢀ-Bn), 74.34 (C-51), 74.20
3 H, H-31, H-21, 0H-62), 4.17 (dd, 1 H, J5,6 2.0 Hz,
0
0
0
J6,6 12.2 Hz, H-6 2), 4.08 (dd, 1 H, J5,6 2.2 Hz, J6,6
(Cꢀ-Bn), 72.24 (Cꢀ-All), 71.89 (C-52 ), 70.75 (C-32 ),
0
0
0
11.4 Hz, H-61), 3.91 (dd, 1 H, J5,6 2.0 Hz, H-601),
3.73 (s, 3 H, OMe), 3.63±3.54 (m, 3 H, H-51, H-41,
H-52), 2.56 (d, 1 H, J 3.6 Hz, OH), 2.13, 2.03, 1.87 (
3 s, 3 H each, 3 Ac); 13C NMR: ꢂ 97.67 (C-12),
96.57 (C-11), 78.53 (C-31), 74.83 (C-51), 74.34 (Cꢀ-
Bn), 72.54 (C-41), 71.95 (C-52), 70.82 (C-32), 68.74
(C-42), 68.29 (C-61), 61.59 (C-62), 55.51 (C-OMe),
55.17 (C-21), 54.32 (C-22), 20.78, 20.52, 20.43 (3
MeC=O); FABMS: Calcd for C48H46N2O17: m/z
922.3. Found: m/z 945.3 (M + Na)+.
70.64 (Cꢀ-All), 69.40 (C-62), 68.50 (C-42 ), 68.11
0
0
(C-61), 61.31 (C-62 ), 55.35 (C-OMe), 55.34 (C-21),
0
54.47 (C-22 ), 20.61, 20.38, 20.27 (3 MeC=O);
FABMS: Calcd for C74H76N2O22: m/z 1344.5.
Found: m/z 1367.6 (M + Na)+. Anal. Calcd for
C74H76N2O22: C, 66.07; H, 5.69; N, 2.08. Found:
C, 65.98; H, 5.78; N, 1.75.
7ꢀ: Rf 0.47 (3:1 toluene±EtOAc,); 1H NMR
(600 MHz): ꢂ 5.90 (m, 2 H, 2 CH2=CH-), 5.64 (d,
1 H, J1,2 7.3 Hz, H-11), 5.62 (dd, 1 H, J3,4 7.4 Hz,
0
0
p-Methoxyphenyl 3,6-di-O-allyl-2,4-di-O-benzyl-
b-d-mannopyranosyl-(1!4)-[3,4,6-tri-O-acetyl-2-
deoxy-2-phthalimido-b-d-glucopyranosyl-(1!6)]-
3-O-benzyl-2-deoxy-2-phthalimido-b-d-glucopyrano-
side (7).ÐTo a stirred mixture of compound 5
(550 mg, 0.6 mmol), silver alumina±silicate (1.4 g,
4.2 mmol) and 4A MS (1.4 g) in CH2Cl2 (10 mL)
was added a solution of compound 6 (1.05 g,
2.1 mmol) in CH2Cl2 (5 mL) at 15 ꢀC. The mix-
ture was allowed to warm up to 0 ꢀC in 1 h and
then to room temperature overnight. Solids were
®ltered o€, and the solution was concentrated to
dryness in vacuo. The resulting residue was sepa-
rated by silica gel CC (5:1 toluene±EtOAc) to
a€ord compound 7 (177 mg, 22%), its ꢀ-isomer 7ꢀ
(252 mg, 31%) and recovered 5 (190 mg), all as
white solids. 7: [ꢀ]d +45.1ꢀ (c 0.2, CHCl3); Rf 0.40
(3:1 toluene±EtOAc); 1H NMR (600 MHz): ꢂ 7.81±
6.73 (m, 27 H, H-aromatic), 5.95, 5.77 (2 m, 1 H
J2,3 10.4 Hz, H-32 ), 5.54 (d, 1 H, J1,2 8.6 Hz, H-12 ),
5.32±5.08 (m, 4 H, 2 CH2=), 5.15 (s, 1 H, H-12),
0
3.29 (m, 1 H, J 9.8, 5.4, 1.5 Hz, H-52 ), 2.08, 2.00,
1.84 ( 3 s, 3 H each, 3 Ac); 13C NMR: ꢂ 100.86 (C-
0
12), 97.09 (C-12 ), 95.49 (C-11), 80.38, 79.19, 75.35,
75.19, 74.86, 74.68, 74.66, 74.63, 72.96, 72.38,
72.18, 71.48, 71.07, 70.93, 69.31, 68.52, 68.203,
61.28, 55.31 (C-OMe), 55.29 (C-21), 54.52 (C-22 ),
20.67, 20.36, 20.33 (3 MeC=O).
p-Methoxyphenyl 2,4-di-O-benzyl-b-d-mannopyr-
anosyl-(1!4)-[3,4,6-tri-O-acetyl-2-deoxy-2-phtha-
limido-b-d-glucopyranosyl-(1!6)]-3-O-benzyl-2-
deoxy-2-phthalimido-b-d-glucopyranoside (8).ÐA
solution of [Ir(COD)(PMePh2)2]PF6 (20 mg,
0.024 mmol) in THF (15 mL) was stirred under H2
until the red solution became colorless. Then the
H2 atmosphere was replaced with N2, and a solution
of 7 (230 mg, 0.17 mmol) in THF (5 mL) was added.
The mixture was stirred at room temperature for

Z.-W. Guo et al./Carbohydrate Research 306 (1998) 539±544
543
1 h and concentrated in vacuo. The residue was
dissolved in 90% aq acetone (20 mL) and treated
with HgO (40 mg) and HgCl2 (350 mg) for 1 h. The
mixture was ®ltered through Celite and the ®ltrate
was concentrated in vacuo. CC (5±3:1 toluene±
EtOAc) of the residue gave compound 8 (181 mg,
84%) as a white solid. 8: [ꢀ]d +24.9ꢀ (c 1.1,
7.60±6.62 (m, 57 H, H-aromatic), 5.63 (dd, 1 H,
0
J3,4 9.4 Hz, J2,3 10.7 Hz, H-32 ), 5.61 (d, 1 H, J1,2
0
8.3 Hz, H-11), 5.50 (d, 1 H, J1,2 8.8 Hz, H-12 ), 5.48
(bd, 1 H, J2,3 1.0 Hz, H-23), 5.28 (bd, 1 H, J2,3
0
0
1.0 Hz, H-23 ), 5.11 (dd, 1 H, J4,5 9.9 Hz, H-42 ),
5.09 (bs, 1 H, H-13), 4.94, 4.84 (2 d, 1 H 0each, J
11.7, 12.0 Hz, H-Bn), 4.83 (bs, 1 H, H-13 ), 4.79,
4.77, 4.73, 4.67, 4.61, 4.59, 4.55 (7 d, 1 H each, J
13.2, 10.8, 11.7, 11.2, 11.2, 12.2, 11.7 Hz, H-Bn),
1
CHCl3); Rf 0.16 (2:1 toluene±EtOAc); H NMR
(600 MHz): ꢂ 7.74±6.73 (m, 27 H, H-aromatic),
0
5.71 (dd, 1 H, J3,4 9.3 Hz, J2,3 10.7 Hz, H-32 ), 5.61
4.48±4.44 (m, 4 H, H-Bn), 4.42 (s, 1 H, H-12), 4.41±
0
(d, 10H, J1,2 7.8 Hz, H-11), 5.52 (d, 1 H, J1,2 8.3 Hz,
4.35 (m, 4 H, H-Bn), 4.33 (dd, 1 H, H-22 ), 4.23
0
H-12 ), 5.16 (dd, 1 H, J4,5 10.2 Hz, H-42 ), 5.00,
4.89, 4.83, 4.69 (4 d, 1 H each, J 11.6, 12.2, 11.2,
(dd, J2,3 10.7 Hz, H-21), 4.20±4.16 (m, 3 H, H-31,
0
H-Bn, H-62 ), 0 4.06 (dd, 1 H, J5,6 2.0 Hz, J6,6
0
0
11.6 Hz, H-Bn), 4.58 (s, 1 H, H-12), 4.56, 4.39 (2 d,
1 H each, J 11.2, 12.2 Hz, H-Bn), 4.37 (dd, 1 H, H-
12.3 Hz, H-602 ), 3.95 (dd, 1 H, J2,3 3.4 Hz, J3,4
9.3 Hz, H-33), 3.93 (m, 1 H, H-53), 3.90 (bs, 1 H,
H-23), 3.87±3.62 (m, 14 H, other protons of sugar
0
22 ), 4.33±4.30 (m, 2 H, H-31, 0H-21), 4.28 (dd, 1 H,
J5,6 4.4 Hz, J6,6 12.5 Hz, H-62 ), 4.16 (dd, 1 H, J5,6
rings), 3.73 (0s, 3 H, OMe), 3.51 (bd, 1 H, J6,6
0
0
0
0
0
2.5 Hz, H-6 2 ), 4.04 (dd, 1 H, J5,6 2.9 Hz, J6,6
10.0 Hz, H-63 ), 3.48 (m, 1 H, H-51), 3.30 (m, 1 H,
0
0
0
10.7 Hz, H-61), 3.87±3.79 (m, 3 H, H-22, H-41, H-
601), 3.75 (s, 3 H, OMe), 3.75±3.67 (m, 2 H, H-62,
H-52 ), 3.07 (m, 1 H, H-52), 2.11, 2.04, 2.00, 1.90,
1.82 ( 5 s, 3 H each, 5 Ac); 13C NMR: ꢂ 170.67,
170.04, 169.95, 169.76, 169.36 (5 C=O of Ac),
H-51), 3.64 (dd, 1 H, J2,3 3.9 Hz, J3,4 9.3 Hz, H-32),
0
3.56 (m, 1 H, H-52 ), 3.46 (dd, 1 H, J4,5 9.6 Hz, 0H-
167.58, 167.51, 167.46, 167.40 (4 C=O of Phth),
101.82 (C-12), 99.55 (C-13), 98.22 (C-13 ), 96.98 (C-
0
42), 3.42 (dd, 1 H, J5,6 5.4 Hz, J6,6 12.2 Hz, H-6 2),
0
0
3.8 (ddd, 1 H, J 9.3, 3.4, 6.8 Hz, H-52), 2.49 (d, 1 H,
J 9.1 Hz, OH), 2.09, 2.04, 1.87 ( 3 s, 3 H 0each, 3
Ac); 13C NMR: ꢂ 101.69 (C-12), 97.79 (C-12 ), 97.11
(C-11), 79.91 (C-41), 78.78 (C-22), 77.04 (C-31),
76.84 (C-42), 75.81 (C-52), 75.60 (Cꢀ-Bn), 75.06
(Cꢀ-Bn), 74.81 (C-51), 74.75 (Cꢀ-Bn), 704.29 (C-32),
12 ), 96.30 (C-11), 69.17, 68.79, 66.60, 66.31 (4 C-6
0
of sugar 1, 2, 3, 30), 61.53 0(C-62 ), 55.38 (C-OMe),
55.26 (C-21), 54.32 (C-22 ), 20.94, 20.72, 20.69,
20.43, 20.31 (5 MeC=O); FABMS: Calcd for
C126H128N2O34: m/z 2212.8. Found: m/z 2236.0 (M
+ Na)+. Anal. Calcd for C126H128N2O34: C,
68.34; H, 5.83; N, 1.27. Found: C, 68.15; H, 5.80;
N, 1.24.
0
0
72.56 (C-52 ), 71.21 (C-32 ), 69.02 (C-42 ), 67.89 (C-
0
61), 62.66 (C-62), 61.94 (C-62 ), 55.87 (C-OMe),
0
55.65 (C-21), 54.61 (C-22 ), 21.12, 20.90, 20.79 (3
p-Methoxyphenyl 3,4,6-tri-O-benzyl-a-d-manno-
pyranosyl-(1!3)-[3,4,6-tri-O-benzyl-a-d-manno-
pyranosyl-(1!6)]-2,4-di-O-benzyl-b-d-mannopyr-
anosyl-(1!4)-[2-deoxy-2-acetamido-b-d-glucopyr-
anosyl-(1!6)]-3-O-benzyl-2-deoxy-2-acetamido-b-
d-glucopyranoside (11).ÐA solution of 10 (20 mg,
9.0 mmol) and ethylenediamine (0.15 mL) in n-
butanol (2 mL) was stirred at 90 ꢀC for 2 days.
After concentration in vacuo, the residue was dis-
solved in MeOH (10 mL), and to the solution was
added acetic anhydride (5 mL) at 0 ꢀC. The mixture
then allowed to warm to room temperature. At the
end of 4 h, the mixture was concentrated in vacuo,
and the residue was ®rst puri®ed by LH-20 gel ®l-
tration and then by HPLC (Intersil Prep-Sil col-
umn, 10Â250 mm; Det. 254 nm; Eluent: 8:92
EtOH±CHCl3, 4 mL/min; tR=9.72 min) to a€ord
11 (12.4 mg, 74%) as a white solid. 11: [ꢀ]d +11.2ꢀ
MeC=O); FABMS: Calcd for C68H68N2O22: m/z
1264.4. Found: m/z 1287.5 (M + Na)+.
p-Methoxyphenyl 2-O-acetyl-3,4,6-tri-O-benzyl-
a-d-mannopyranosyl-(1!3)-[2-O-acetyl-3,4,6-tri-O-
benzyl-a-d-mannopyranosyl-(1!6)]-2,4-di-O-benzyl-
b-d-mannopyranosyl-(1!4)-[3,4,6-tri-O-acetyl-2-
deoxy-2-phthalimido-b-d-glucopyranosyl-(1!6)]-
3-O-benzyl-2-deoxy-2-phthalimido-b-d-glucopyrano-
side (10).ÐTo a stirred mixture of 8 (118 mg,
0.093 mmol), AgOTf (130 mg, 0.50 mmol) and 4A
MS (1.0 g) in CH2Cl2 (8 mL) was added a solution
of compound 9 (190 mg, 0.37 mmol) in CH2Cl2
(30 mL) at 40 ꢀC. The mixture was gradually
warmed to room temperature and stirred over-
night. It was ®ltered through Celite and the ®ltrate
was concentrated in vacuo. The residue so
obtained was puri®ed by silica gel CC (6±8:1
toluene±EtOAc) to gave 10 (173 mg, 84%) as a
white solid. 10: [ꢀ]d +32.5ꢀ (c 1.5, CHCl3); Rf
1
(c 0.4, CHCl3); H NMR (600 MHz): ꢂ 7.34±6.14
(m, 45 H, H-aromatic), 6.90, 6.79 (2 d, 2 H each, J
8.8 Hz, H-aromaticMp), 5.90 (d, 1 H, J 6.8 Hz,
1
0.42 (3:1 toluene±EtOAc); H NMR (600 MHz): ꢂ

544
Z.-W. Guo et al./Carbohydrate Research 306 (1998) 539±544
0
0
NH1), 5.76 (bs, 1 H, NH2 ), 5.38 (d, 1 H, J1,2
2.4 Hz, 5.9 Hz, H-52 ), 2.04, 1.90 (2 s, 3 H each, 2
6.0 Hz, H-11), 5.23 (s, 1 H, H-13), 4.97 (s, 1 H, H-
13 ), 4.87±4.76 (m, 5 H, H-Bn), 4.64, 4.61 (2 d, 1 H
Ac); MOLDI-TOF-MS: Calcd for C41H64N2O27:
m/z 1016.9. Found: m/z 1039.2 (M + Na)+, 1055.2
(M + K)+.
0
each, J 11.2, 12.2 Hz, H-Bn), 4.57 (s, 2 H, H-Bn),
4.55 (s, 1 H, H-12), 4.54±4.37 (m, 8 H, H-Bn), 4.38
(d, 10H, J 12.2 Hz, H-Bn), 4.24 (d, 1 H, J1,2 8.3 Hz,
H-12 ), 4.09 (dd, 1 H, J 6.3, 6.8 Hz, H-31), 3.99 (bs,
Acknowledgements
0
1 H, H-23 ), 3.96±3.59 (m, 23 H, other sugar ring
This work was ®nancially supported by the Spe-
cial Co-ordination Funds of the Science and Tech-
nology Agency of the Japanese Government and
partly by CREST program of Japan Science and
Technology Corporation. Z.-W.G. is grateful for a
RIKEN Fellowship and thanks Dr. Yuko Naka-
hara for her generous helps. We thank Dr. P.
Stanley for many helpful discussions, Dr. S. Kur-
ono and Dr. N. Dohmae for MS measurements,
Dr. J. Uzawa and his sta€ for NMR measurements
and Ms. A. Takahashi for technical assistance.
protons)0, 3.75 (s, 3 H, OMe), 3.47±3.44 (m, 2 H, H-
0
0
42 , H-22 ), 3.37±3.33 (m, 2 H, H-32 , H-51), 3.19 (m,
0
1 H, H-52 ), 1.75, 1.61 (2 s, 3 H each, 2 Ac);
FABMS: Calcd for C104H118N2O27: m/z 1826.8.
Found: m/z 1850.0 (M + Na)+. Anal. Calcd for
C104H118N2O27: C, 68.33; H, 6.51; N, 1.53. Found:
C, 67.88; H, 6.23; N, 1.72.
p-Methoxyphenyl a-d-mannopyranosyl-(1!3)-
[a-d-mannopyranosyl-(1!6)]-b-d-mannopyranosyl-
(1!4)-[2-deoxy-2-acetamido-b-d-glucopyranosyl-
(1!6)]-2-deoxy-2-acetamido-b-d-glucopyranoside
(2).ÐCompound 11 (7.0 mg, 3.8 mmol) in water
(2.0 mL) and MeOH (3.0 mL) was stirred with 20%
Pd(OH)2±C (20 mg) under a hydrogen atmosphere
at room temperature for 2 days. After ®ltration
and concentration in vacuo, the residue was dis-
solved in water and freeze-dried to get 2 (3.9 mg) as
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1
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1
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0
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