Synthesis of a carboxyl linker containing Pk trisaccharide

Article abstract of DOI:10.1016/j.carres.2004.10.024

An efficient synthesis of a P^k trisaccharide with a functionalized side arm at the reducing end for conjugation to other molecules is presented. Construction of the P^k trisaccharide with a high α-selectivity was achieved in high yiel

Full text of DOI:10.1016/j.carres.2004.10.024

Carbohydrate
RESEARCH
Carbohydrate Research 340 (2005) 49–57
Synthesis of a carboxyl linker containing Pk trisaccharide
Shu-Yi Hsieh,a,b Mi-Dan Jan,a Laxmikant N. Patkar,a
Chien-Tien Chenb and Chun-Cheng Lina,c,
*
aInstitute of Chemistry, Academia Sinica, Nankang, Taipei 115, Taiwan
bDepartment of Chemistry, National Taiwan Normal University, Taipei 106, Taiwan
cDepartment of Applied Chemistry, National Chiao Tung University, Hsinchu 300, Taiwan
Received 27 May 2004; received in revised form 2 August 2004; accepted 30 October 2004
Available online 8 December 2004
Abstract—An efficient synthesis of a Pk trisaccharide with a functionalized side arm at the reducing end for conjugation to other
molecules is presented. Construction of the Pk trisaccharide with a high a-selectivity was achieved in high yield by coupling a reactive
galactosyl phosphite donor with a lactosyl acceptor.
Ó 2004 Elsevier Ltd. All rights reserved.
Keywords: Pk antigen; Galactosyl phosphite; Glycosylation; a-Selectivity
1. Introduction
ride units to scaffolds depends critically on the
introduction of an appropriately functionalized linker
moiety onto the saccharide unit. Therefore, synthetic
routes must be developed to attach a linker moiety to
the reducing end of the saccharide ligand. The develop-
ment of the multivalent Pk-trisaccharide ligand is of par-
ticular interest3 and the present work describes an
efficient synthesis of Pk-trisaccharide with a linker that
has carboxyl functionality.
Bacterial AB5 toxins,1 such as shiga like toxins (SLTs)
and cholera toxins, consisting of a single catalytically ac-
tive A subunit and a pentamer of B subunits govern a
wide range of toxic effects in human populations. SLTs
have been shown to enter target cells by a crucial recog-
nition event involving tight binding of B subunits with
the cell surface glycolipid globotriosylceramide [Gb3,
a-D-Gal-(1!4)-b-D-Gal-(1!4)-b-D-Glc-1!Ceramide].1b,2
The binding of SLTs to multiple terminal trisaccharide
of Gb3, Pk-trisaccharide [a-D-Gal-(1!4)-b-D-Gal-
(1!4)-b-D-Glc], results in specific recognition and tight
interaction.1–3 Such multiple simultaneous molecular
contacts are called as multivalent interaction.4 The de-
sign and synthesis of multivalent ligands to block inter-
actions between toxin B pentamer and its cell-surface
receptors has a potential in drug design.3
2. Result and discussion
The target Pk-trisaccharide 1 (Fig. 1) comprises of a lac-
tosyl unit joined to a galactosyl unit via an a(1!4) gly-
cosidic bond and a linker that contains a carboxylic
acid, which can be conjugated with scaffolds. Figure 1
depicts the retrosynthetic analysis of the Pk trisaccharide
1. The choice of this synthetic route, over two linear
consecutive glycosylations, to assemble the trisaccharide
with the linker moiety was dictated by many consider-
ations. First, the literature9 suggests that the coupling
of the linker moiety to the assembled trisaccharide is
not very efficient and the resulting product is not amena-
ble to further chemical modification. Thus, the required
linker moiety must be introduced at an early stage of the
Numerous diverse scaffolds have been generated as
powerful multivalent carbohydrate carriers, including
low-molecular weight displays,3c,5 copolymers,6 dendri-
mers7 and nanoparticles.8 The anchoring of the saccha-
*
Corresponding author. Tel.: +886 2 27898648; fax: +886 2 27835007;
e-mail: cclin@chem.sinica.edu.tw
0008-6215/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2004.10.024

50
S.-Y. Hsieh et al. / Carbohydrate Research 340 (2005) 49–57
OH
O
HO
HO
link with scaffolds
OH
HO
OH
O
O
OH
O
O
HO
O
HO
O
OH
OH
1
OBz
O
HO
BzO
OBn
O
BnO
BnO
OBz
O
OMe
O
O
O
BzO
BzO
OP(OBn)2
BnO
OBz
2
3
Figure 1. Retrosynthesis of compound 1.
assembly of the trisaccharide. Secondly, lactose is a
readily available starting compound to which pentenyl
alcohol can be efficiently attached in only a few steps.10
The pentenyl moiety can be easily functionalized to a
carboxylic acid to furnish the lactosyl intermediate 3.11
Finally, although lactoside 3 with electron-withdrawing
benzoyl groups markedly reduces the nucleophilicity of
the 40-OH group, such acceptors undergo glycosylation
with high stereoselectivity.12 A related reactive donor
is required to obtain a good yield in the glycosylation
reaction with the less reactive acceptor. Galactosyl phos-
phite 2 was selected as donor, because glycosyl phosph-
ites can be easily prepared,9,13 are moderately stable but
highly reactive in glycosylation conditions and are acti-
vated by various reagents14b over a wide range of tem-
peratures15,16 (ꢀ78 °C to room temperature). Furthermore,
benzyl-protected glycosyl phosphites are known to be
highly a-selective during glycosylation reactions.14,16
Also, galactosyl phosphite donors had not been previ-
ously used in the synthesis of trisaccharide 1 and the
use of this donor should be explored. Based on these
considerations, trisaccharide 1 was constructed by using
galactosyl phosphite 2 as a donor and lactoside 3 as an
acceptor.
(47% yield for three steps). Treatment of 5 with NBS
in acetone/water mixture18 gave galactoside with a free
anomeric hydroxyl group, which was then reacted with
DDP (dibenzyl N,N-diethyl phosphoramidite) in the
presence of 1H-tetrazole13,14 to produce the required
benzyl protected galactosyl donor 2 with a/b = 9/1
(69% yield for two steps). Notably, donor 2 can be stored
at 4 °C for at least 1 month without decomposing.
The synthesis of lactosyl 3 began with lactose deriva-
tive 6, which was obtained according to a method in the
literature, as shown in Scheme 2.10 The deacetylation of
compound 6 was followed by the selective protection of
the 40 and 60-OH hydroxyl groups of the resulting prod-
uct as benzylidene acetal.10 The remaining free hydroxyl
groups were then benzoylated to afford 8; then acid
hydrolysis of benzylidene acetal yielded 7. Notably,
the four-step process was performed without purifying
each intermediate, resulting in a 44% overall yield. Selec-
tive benzoylation of the primary hydroxyl group of com-
pound 7 was achieved using benzoyl chloride at ꢀ78 °C,
to produce lactoside 8 (73%) with a free hydroxyl at the
40-position.19 Ruthenium trichloride11 catalyzed the oxi-
dation of the olefin moiety in 8, generating the acceptor
9 (60%). Moreover, a competition between the free 40-
OH group of galactoside and the carboxylic acid of
the linker in the acceptor 9 during the glycosylation with
the donor 2 was anticipated. Thus, the carboxylic acid
group of 9 was selectively protected as the methyl ester
using TMSCl in methanol conditions,20 to afford 3 with
an 80% yield.
The galactosyl donor 2 was prepared from pentaace-
tate galactoside 4 in a three-step process as shown in
Scheme 1. Compound 4 was treated with thiocresol in
the presence of BF3ÆEt2O17 and then the acetate groups
were removed with NaOMe/MeOH; benzylation of the
resulting residues yielded the desired thiogalactoside 5
OBn
BnO
OBn
OAc
O
BnO
BnO
AcO
AcO
O
O
a, b, c
d, e
BnO
S
OAc
OP(OBn)2
BnO
BnO
AcO
2
4
5
Scheme 1. Synthesis of galactosyl donor 2. Reagents and conditions: (a) thiocresol, BF3ÆOEt2, CH2Cl2, 14 h, rt, 77%; (b) NaOMe, MeOH, 5 h, rt,
˚
88%; (c) NaH, TBAI, BnBr, DMF, 16 h, rt, 69%; (d) NBS, acetone/water (1:9), 3 h, rt, 80%; (e) 1H-tetrazole, DDP, MeCN, 4 A-MS, 3 h, rt,
a:b = 9:1, 86%.

S.-Y. Hsieh et al. / Carbohydrate Research 340 (2005) 49–57
51
AcO
AcO
OAc
O
HO
BzO
OH
O
OBz
O
OAc
O
a~d
O
O
O
O
AcO
BzO
AcO
BzO
AcO
BzO
6
7
HO
BzO
OBz
O
HO
OBz
O
OBz
O
OBz
O
O
e
g
f
O
O
BzO
O
O
OH
BzO
BzO
BzO
BzO
BzO
BzO
8
9
3
Scheme 2. Synthesis of lactoside acceptor 3. Reagents and conditions: (a) NaOMe, MeOH; (b) benzaldehyde dimethyl acetal, CSA, MeCN/DMF
(5.2), rt; (c) BzCl, pyridine, 14 h, rt; (d) TFA/H2O, CH2Cl2, rt, 4 h, 4 steps 44%; (e) BzCl, pyridine, CH2Cl2, ꢀ78 °C–rt, 10 h, 73%; (f) RuCl3/NaIO4,
CH2Cl2/MeCN/H2O (2:2:3), 2 h, rt, 60%; (g) TMSCl, MeOH, 14 h, rt, 80%.
With three acceptors, 3, 8, and 9, and donor 2 in
hand, glycosylation between the acceptors and the
donor could be explored. Table 1 summarizes the results.
Glycosylation between acceptor 8 and donor 2 at
ꢀ15 °C in dichloromethane with 0.1 equiv of TMSOTf
(trimethylsilyltriflate) as an activator gave the corre-
sponding trisaccharide 10 in low yield (data not shown).
Increasing the amount of activator to 0.5 or 1.0 equiv
and increasing the temperature from ꢀ15 °C to 0 °C
slightly increased yields (entries 1 and 2). Disappoint-
ingly, acceptor 9 failed to react with 2 under similar
reaction conditions as were employed in the synthesis
of 10 (entries 3 and 4). Finally, acceptor 3 was reacted
with donor 2 at various temperatures, as shown in en-
tries 5–8. The yield of the corresponding trisaccharide
12 depended on the reaction temperature, with the max-
imum obtained yield being 75% at 0 °C. The mixture of
compounds 3 and 12 was very difficult to separate by
column chromatography or HPLC. Consequently, the
yield was determined based on NMR analysis. Notably,
only the desired a-anomer products were obtained in the
glycosylations of 2 with 3 and 8. The chemical shift and
Table 1. Glycosylation of donor 2 with acceptors 3, 8, and 9
2
Acceptor
Temperature (°C)
Equivalents of TMSOTf
Yield (%)
Product
OBn
O
BnO
BnO
BnO
OBz
O
O
1
2
8
8
ꢀ15
0.5
1
35
45
OBz
O
ꢀ15 ꢁ 0
BzO
O
O
BzO
BzO
OBz
10
OBn
O
BnO
BnO
BnO
OBz
O
3
4
9
9
ꢀ15
ꢀ23
1
1
—
—
OBz
O
OH
O
BzO
O
O
O
BzO
BzO
OBz
11
OBn
O
BnO
BnO
5
6
7
8
3
3
3
3
ꢀ23
ꢀ15
0
1
1
1
1
48
50
75
72
BnO
OBz
O
O
OBz
OMe
O
O
BzO
O
O
OBz
Rt
BzO
BzO
12

52
S.-Y. Hsieh et al. / Carbohydrate Research 340 (2005) 49–57
OH
HO
OBn
O
BnO
BnO
O
HO
BnO
HO
OBz
O
OBz
O
O
OBz
O
OBz
O
a
OMe
O
OMe
O
O
BzO
O
BzO
O
O
O
BzO
BzO
BzO
BzO
BzO
BzO
13
12
OAc
O
AcO
AcO
AcO
OAc
O
O
c
b
OAc
O
1
OH
O
AcO
O
AcO
O
AcO
AcO
14
Scheme 3. Reagents and conditions: (a) H2(g)/Pd(OH)2, AcOH, 70%; (b) NaOH, CH2Cl2/MeOH/H2O (2:3:1), 79%; (c) pyridine, Ac2O, 60%.
coupling constant of H-1 at the newly formed anomeric
center were 4.70 ppm and 3.2 Hz for 10 and 4.62 ppm
and 2.0 Hz for 12, respectively.
dried glassware (120 °C) under an atmosphere of nitro-
gen unless indicated otherwise. All solvents were dried
and distilled by standard techniques.
An attempt to oxidize the olefin of 10 resulted in
decomposition. As depicted in Scheme 3, trisaccharide
12 was subjected to partial deprotection of the benzyl
groups, by hydrogenation with a catalytic amount of
Pd(OH)2, to yield separable compound 13 in 70% yield.
Compound 13 was further deprotected using sodium
hydroxide in a mixed solvent of dichloromethane, meth-
anol, and water to yield the desired target molecule 1
(79%). The trisaccharide 1 was characterized as a fully
acetylated derivative 14.
4.2. Synthesis
4.2.1. p-Methylphenyl 2,3,4,6-tetra-O-benzyl-1-thio-b-D-
galactopyranoside (5). To a solution of compound 4
(5 g, 12.81 mmol) in CH2Cl2 (25 mL) was added thiocre-
sol (1.9 g, 15.37 mmol) under N2 at room temperature
followed by addition of boron trifluoride diethyl ether-
ate (3.25 mL, 25.62 mmol). The resulting mixture was
stirred at room temperature for 12 h. Solvent was evap-
orated in vacuo, and the residue was dissolved in
CH2Cl2 and washed with saturated NaHCO3(aq), water
and brine. The organic extracts were dried over MgSO4,
concentrated and recrystallized from EtOAc/hexane to
give the desired compound (4.15 g, 71%). Rf = 0.26
3. Conclusion
In conclusion, a Pk trisaccharide was constructed using
galactosyl phosphite donor 2 and lactoside 3 with high
a-selectivity in the formation of the glycosidic bond in
a high yield. A study of the conjugation of 14 with var-
ious of scaffolds and related multivalent effects will be
published in due course.
1
(1:2, EtOAc/hexane); H NMR (400 MHz, CDCl3): d
1.98 (s, Ac, 3H), 2.05 (s, Ac, 3H), 2.11 (s, Ac, 3H),
2.12 (s, Ac, 3H), 2.36 (s, Me, 3H), 3.92 (td, J = 1.2 Hz,
J = 6.8 Hz, H-5, 1H), 4.12 (dd, J = 6.8 Hz, J =
11.6 Hz, H-6a, 1H), 4.19 (dd, J = 6.8 Hz, J = 11.6 Hz,
H-6b, 1H), 4.66 (d, J = 10.0 Hz, H-1, 1H), 5.05 (dd,
J = 3.6 Hz, J = 10.0 Hz, H-3, 1H), 5.22 (t, J = 10.0 Hz,
J = 10.0 Hz, H-2, 1H), 5.41 (dd, J = 1.2 Hz, J =
3.6 Hz, H-4, 1H), 7.40 (d, J = 8.0 Hz, Ph, 2H), 7.42 (d,
J = 8.0 Hz, Ph, 2H).
To a solution of the above compound (4.15 g,
9.13 mmol) in CH3OH (83 mL) was added NaOMe
(0.42 g) under N2 at rt. The reaction mixture was stirred
for 7 h at room temperature. The solvent was evapo-
rated and the residue was purified by column chroma-
tography to give the desired compound (2.30 g, 88%).
Rf = 0.48 (1:4, MeOH/CH2Cl2); 1H NMR (400 MHz,
CDCl3): d 2.38 (s, Me, 3H), 3.55 (dd, J = 3.0 Hz,
J = 9.2 Hz, H-3, 1H), 3.58–3.67 (m, H-2, H-5, 2H),
3.77 (dd, J = 5.6 Hz, J = 11.6 Hz, H-6a, 1H), 3.83 (dd,
4. Experimental
4.1. General methods
1H and 13C NMR spectra were recorded on Bruker AM-
1
400 or 500 MHz. Assignment of H NMR spectra was
achieved using 2D methods (COSY). Chemical shifts
were expressed in ppm using residual CHCl3 as refer-
ence. High-resolution mass spectra were obtained by
means of a Micromass (Autospec) mass spectrometer.
Analytical thin-layer chromatography (TLC) was per-
formed on precoated plates (silica gel 60 F-254). Silica
gel 60 (E. Merck Co.) was employed for all flash chro-
matography. All reactions were carried out in oven-

S.-Y. Hsieh et al. / Carbohydrate Research 340 (2005) 49–57
53
J = 6.4 Hz, J = 11.6 Hz, H-6b, 1H), 3.96 (d, J = 3.0 Hz,
H-4, 1H), 4.57 (d, J = 9.6 Hz, H-1, 1H), 7.19 (d,
J = 8.0 Hz, Ph, 2H), 7.52 (d, J = 8.0 Hz, Ph, 2H).
78.53, 88.69, 115.98, 116.07, 116.16, 116.22, 116.28,
116.38, 116.54, 116.67, 116.90.
DMF (20 mL) was added to a flask containing the
above compound (0.57 g, 1.99 mmol) and TBAI
(46 mg, 0.12 mmol), then cooled to 0 °C. NaH (0.38 g,
15.93 mmol) was added to the stirred solution over
30 min. BnBr (1.89 mL, 15.93 mmol) was added drop-
wise and stirred at rt for 12h. The solvent was evapo-
rated under reduced pressure, and the residue was
dissolved in EtOAc and washed with water and brine.
The organic layer extracts were dried over MgSO4 and
purified by silica gel chromatography (1:4, EtOAc/hex-
ane) to give compound 5 (0.89 g, 69%). Rf = 0.67 (1:4,
4.2.3. Pent-4-enyl 2,20,3,30,6-penta-O-benzoyl-b-D-lacto-
side (7). The compound 610 (6.65 g, 9.44 mmol) was
dissolved in MeOH (133 mL) then NaOMe (66.5g)
was added. The reaction mixture was stirred at rt for
7h. The solvent was evaporated to obtain a desired com-
pound (3.67g), which was used in the next step without
further purification, Rf = 0.08 (1:4, MeOH/CH2Cl2).
Solution of above compound (3.667 g, 9.59 mmol) in
CH3CN/DMF (5:2) (56 mL) was added benzaldehyde
dimethyl acetal (3.76 mL, 24.94 mmol) and camphor-
sulfonic acid (111.4 mg, 0.48 mmol) under N2. After stir-
ring for 16h at rt, the mixture was diluted with CH2Cl2.
1
EtOAc/hexane); H NMR (400 MHz, CDCl3): d 2.24
(s, Me, 3H), 3.52–3.61 (m, H-3, H-5, H-6, 4H), 3.85 (t,
J = 9.6 Hz, J = 9.6 Hz, H-2, 1H), 3.92 (d, J = 2.8 Hz,
H-4, 1H), 4.37 (d, J = 11.6 Hz, Bn, 1H), 4.42 (d,
J = 11.6 Hz, Bn, 1H), 4.54 (d, J = 10.0 Hz, Bn, 1H),
4.55 (d, J = 11.6 Hz, Bn, 1H), 4.67 (s, Bn-6, 2H), 4.68
(d, J = 10.0 Hz, Bn, 1H), 4.75 (d, J = 10.0 Hz, Bn,
1H), 4.91 (d, J = 11.6 Hz, H-1, 1H), 6.94 (d,
J = 8.0 Hz, SPh, 2H), 7.21–7.35 (m, Bn, 20H), 7.41 (d,
J = 8.0 Hz, 2H).
The residue was washed with saturated NaHCO3(aq),
and the organic layer was dried over MgSO4 and then
concentrated to give desired compound (4.38g), which
was used in the next step without further purification.
Rf = 0.60 (1:4, MeOH/CH2Cl2).
To a solution of the above compound (4.38 g,
8.79 mmol) in dry pyridine (43 mL), was added benzoyl
chloride dropwised (4.40 mL, 87.91 mmol) under N2.
The reaction mixture was stirred at rt for 15 h and then
CH3OH was added. Solvent was evaporated in vacuo
and the residue was dissolved in EtOAc. Organic layer
was washed with water and a solution of 10% HCl.
The organic extracts were dried over MgSO4 and evap-
orated in vacuo to obtain compound (8.32 g), which was
used in next step without further purification. Rf = 0.32
(1:2, EtOAc/hexane).
4.2.2. 2,3,4,6-Tetra-O-benzyl a/b-D-galactopyranosyl
phosphite (2). NBS (370 mg, 2.09 mmol) was added
to the flask, which contained compound 5 (900 mg,
1.39 mmol) in acetone/water (1:9) (25 mL) stirred under
N2 at rt for 3h. However, if the solution becomes color-
less, excess amount of NBS should be added in small
portions till the orange color persists. The solvent was
evaporated in vacuo, the residue was dissolved in
EtOAc, organic layer was washed with water, saturated
NaHCO3(aq), and brine. The organic layer extracts were
dried over MgSO4 and the residue was purified by col-
umn chromatography (1:2, EtOAc/hexane) to give the
desired compound (0.60 g, 80%). Rf = 0.30 (1:2,
EtOAc/hexane). To a solution of the above compound
(1.5 g, 2.77 mmol) in acetonitrile (15 mL) containing
A
solution of the above compound (8.32 g,
8.28 mmol) in CH2Cl2 (80 mL) was added TFA
(9.22 mL, 124.18 mmol) and 2 drops of H2O. The reac-
tion mixture was stirred at rt for 5 h. The mixture was
then diluted with CH2Cl2 before being washed succes-
sively with water and a saturated NaHCO3(aq). The or-
ganic extracts were dried over MgSO4 and purified by
silica gel chromatography (1:1, EtOAc/hexane) to ob-
32
tain compound 7 (7.12 g, 44% for 4 steps). ½aꢂ 54.889
D
4 A molecular sieve, was added 1H-tetrazole (291 mg,
(c 1.12, CHCl3), Rf = 0.34 (1:1, EtOAc/hexane); 1H
NMR (400 MHz, CDCl3): d 1.41–1.54 (m, H-b, 2H),
1.77–1.90 (m, H-c, 2H), 3.19 (dd, J = 6.8 Hz,
J = 13.2 Hz, H-60, 1H), 3.26–3.31 (m, H-50, H-60, 2H),
3.37 (td, J = 6.4 Hz, J = 10.0 Hz, H-a, 1H), 3.72 (td,
J = 6.4 Hz, J = 10.0 Hz, H-a, 1H), 3.77 (ddd, J =
2.0 Hz, J = 4.8 Hz, J = 9.6 Hz, H-5, 1H), 4.11 (t,
J = 9.6 Hz, H-4, 1H), 4.11–4.12 (m, H-4, 1H), 4.34
(dd, J = 4.8 Hz, J = 12.0 Hz, H-6a, 1H), 4.52 (dd, J =
2.0 Hz, J = 12.0 Hz, H-6b, 1H), 4.61 (d, J = 8.0 Hz, H-
1, 1H), 4.67–4.73 (m, H-e, 2H), 4.71 (d, J = 8.0 Hz, H-
10, 1H), 5.02 (dd, J = 3.6 Hz, J = 10.2 Hz, H-30, 1H),
5.32 (dd, J = 8.0 Hz, J = 9.6 Hz, H-2, 1H), 5.47–5.57
(m, H-d, 1H), 5.66 (dd, J = 9.6 Hz, J = 9.6 Hz, H-3,
1H), 5.67 (dd, J = 8.0 Hz, J = 10.2 Hz, H-20, 1H),
7.13–7.53 (m, Bz, 18H), 7.81–7.96 (m, Bz, 12H); 13C
˚
4.16 mmol) and DDP (1.48 mL, 4.162 mmol) under
N2. The reaction mixture was stirred at rt for 3 h. The
solvent was removed and the residue was purified by col-
umn chromatography (1:2, EtOAc/hexane) to provide
compound 2 (1.80 g, 86%). Rf = 0.62 (1:2, EtOAc/hex-
ane). 1H NMR (400 MHz, CDCl3): d 3.35 (dd,
J = 2.6 Hz, J = 6.2 Hz, H-4, 1H), 3.53–3.62 (m, H-6,
2H), 3.91 (dd, J = 2.6 Hz, J = 9.8 Hz, H-3, 1H), 4.05
(dd, J = 3.6 Hz, J = 9.8 Hz, H-2, 1H), 4.15–4.18 (m, H-
5, 1H), 4.42 (d, J = 12.0 Hz, Bn, 2H), 4.49 (d,
J = 12.0 Hz, Bn, 2H), 4.59 (d, J = 11.2 Hz, Bn, 2H),
4.84 (d, J = 11.2 Hz, Bn, 2H), 5.02–5.13 (m, P(OBn)2,
4H), 5.29 (d, J = 3.6 Hz, H-1, 1H), 7.29–7.38 (m, Bn,
30H); 13C NMR (100 MHz, CDCl3): d 40.92, 69.76,
69.81, 71.03, 71.52, 74.06, 74.52, 74.60, 75.43, 75.43,

54
S.-Y. Hsieh et al. / Carbohydrate Research 340 (2005) 49–57
NMR (100 MHz, CDCl3): d 28.74, 29.94, 62.47, 62.93,
68.27, 69.45, 70.05, 72.17, 73.15, 73.90, 74.52, 76.83,
101.01, 101.57, 115.01, 128.59, 128.64, 128.86, 129.10,
129.28, 129.63, 129.83, 129.89, 129.96, 130.03, 133.39,
133.52, 133.67, 137.92, 165.35, 165.49, 165.78, 166.00,
166.11. HRMS (FAB) Anal. Calcd for C52H50O16
[M+Na]+: 953.2997; found: 953.2986.
4.07–4.12 (m, H-6b0, 1H), 4.14 (d, J = 3.2 Hz, H-40,
1H), 4.21 (t, J = 9.6 Hz, J = 9.6 Hz, H-4, 1H), 4.47
(dd, J = 4.2 Hz, J = 12.2 Hz, H-6a, 1H), 4.59 (d,
J = 11.6 Hz, H-6b, 1H), 4.68 (d, J = 8.2 Hz, H-1, 1H),
4.80 (d, J = 8.0 Hz, H-10, 1H), 5.12 (dd, J = 3.2 Hz,
J = 10.4 Hz, H-30, 1H), 5.42 (t, J = 8.2 Hz, J = 8.2 Hz,
H-2, 1H), 5.73–5.80 (m, H-20, H-3, 2H), 7.21–7.62 (m,
Bz, 15H), 7.91–8.02 (m, Bz, 15H); 13C NMR
(100 MHz, CDCl3): d 24.69, 30.07, 62.05, 62.68, 67.02,
68.82, 69.93, 72.08, 72.88, 73.26, 73.30, 74.29, 76.43,
76.92, 77.23, 77.55, 101.12, 101.28, 128.57, 128.64,
128.64, 128.79, 129.77, 129.84, 129.91, 130.04, 133.442,
133.60, 165.25, 165.49, 165.94, 166.11, 166.21, 177.81.
HRMS (FAB) calcd for C58H53O19 [M+H]+:
1053.3181; found: 1053.3190.
4.2.4. Pent-4-enyl 2,20,3,30,6,60-hexa-O-benzoyl-b-D-lac-
toside (8). To a solution of compound 7 (2 g,
2.15 mmol) and pyridine (40 mL) in CH2Cl2 (60 mL) at
ꢀ78 °C was added benzoyl chloride (0.27 mL,
4.30 mmol). Excess of benzoyl chloride (0.27 mL,
4.30 mmol) was added after 2.5 h. The mixture was
quenched with MeOH after 6 h and the mixture was con-
centrated. The residue was purified by column chroma-
tography (1:1, EtOAc/hexane) to give compound 8
4.2.6. 3-Methoxycarbonylpropyl 20,30,60-tri-O-benzoyl-b-
D-galactopyranosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-gluco-
pyranoside (3). A solution of the compound 9 (100 mg,
0.10 mmol) in dried MeOH (2 mL) was added trimethyl-
silyl chloride dropwise (23 lL, 0.209 mmol) and the mix-
ture was stirred for 20 h at rt. The solvent was
evaporated in vacuo and the residue was purified by col-
32
D
(1.61 g, 73%). ½aꢂ 65.815 (c 0.15, CHCl3), Rf = 0.50
1
(1:1, EtOAc/hexane); H NMR (400 MHz, CDCl3): d
1.52–1.64 (m, H-b, 2H), 1.90–1.97 (m, H-c, 2H), 3.44
(td, J = 6.4 Hz, J = 9.6 Hz, H-a, 1H), 3.62–3.67 (m, H-
50, H-60, 2H), 3.82 (td, J = 6.4 Hz, J = 9.6 Hz, H-a,
1H), 3.86–3.81 (m, H-5, 1H), 4.12–4.06 (m, H-40, H-60,
2H), 4.22 (dd, J = 9.6 Hz, J = 9.6 Hz, H-4, 1H), 4.46
(dd, J = 4.4 Hz, J = 12.0 Hz, H-6a, 1H), 4.59 (dd,
J = 1.6 Hz, J = 12.0 Hz, H-6b, 1H), 4.67 (d, J = 7.6 Hz,
H-1, 1H), 4.79 (d, J = 8.0 Hz, H-10, 1H), 4.81–4.76 (m,
H-e, 2H), 5.15 (dd, J = 3.6 Hz, J = 10.2 Hz, H-30, 1H),
5.43 (dd, J = 7.6 Hz, J = 9.6 Hz, H-2, 1H), 5.55–5.66
(tdd, J = 6.8 Hz, J = 10.8 Hz, J = 17.6 Hz, H-d, 1H),
5.73 (dd, J = 7.6 Hz, J = 10.2 Hz, H-20, 1H), 5.77 (dd,
J = 9.2 Hz, J = 9.6 Hz, H-3, 1H), 7.15–7.64 (m, Bz,
15H), 7.91–8.13 (m, Bz, 15H); 13C NMR (100 MHz,
CDCl3): d 28.59, 29.83, 61.73, 62.62, 66.89, 69.45,
69.75, 71.97, 72.65, 73.07, 73.24, 74.09, 76.34, 101.12,
101.16, 114.93, 128.45, 128.55, 128.71, 128.92, 129.00,
129.53, 129.70, 129.76, 129.84, 129.96, 130.26, 133.25,
133.34, 133.55, 137.81, 165.08, 165.34, 165.76, 165.80,
165.96, 166.12. HRMS (FAB) calcd for C59H54O17
[M+Na]+: 1057.3259; found: 1057.3232.
umn chromatography (1:2, EtOAc/hexane) to give com-
32
pound 3 (92 mg, 91%). ½aꢂ 59.569 (c 1.25, CHCl3),
D
Rf = 0.15 (1:2, EtOAc/hexane); 1H NMR (400 MHz,
CDCl3): d 1.77–1.82 (m, H-b, 2H), 2.23 (t, J = 7.6 Hz,
H-c, 2H), 3.48–3.53 (m, H-a, 1H), 3.49 (s, Me, 3H),
3.65–3.73 (m, H-50, H-60, 2H), 3.81–3.88 (m, H-a, H-5,
2H), 4.13 (dd, J = 5.2 Hz, J = 10.8 Hz, H-50, 1H), 4.17
(d, J = 3.2 Hz, H-40, 1H), 4.22 (t, J = 9.2 Hz,
J = 9.6 Hz, H-4, 1H), 4.48 (dd, J = 4.8 Hz, J = 12.0 Hz,
H-6a, 1H), 4.59 (dd, J = 2.0 Hz, J = 12.0 Hz, H-6b,
1H), 4.69 (d, J = 8.0 Hz, H-1, 1H), 4.81 (d, J = 8.0 Hz,
H-10, 1H), 5.17 (dd, J = 3.2 Hz, J = 10.4 Hz, H-30, 1H),
5.42 (dd, J = 8.0 Hz, J = 9.6 Hz, H-2, 1H), 5.76 (dd,
J = 8.0 Hz, J = 10.4 Hz, H-20, 1H), 5.77 (dd,
J = 9.2 Hz, J = 9.6 Hz, H-3, 1H), 7.23–7.63 (m, Bz,
16H), 7.91–8.03 (m, Bz, 14H); 13C NMR (100 MHz,
CDCl3): d 24.9, 30.16, 51.48, 62.20, 66.72, 67.00, 68.92,
69.94, 72.09, 72.91, 73.24, 73.29, 74.35, 76.41, 101.12,
101.27, 128.51, 128.60, 128.79, 129.04, 129.57, 129.75,
129.82, 129.88, 129.93, 130.02, 133.32, 133.38, 133.56,
165.21, 165.41, 165.85, 165.94, 166.03, 166.18, 173.71.
HRMS (FAB) calcd for C59H54O19 [M+Na]+:
1089.3259; found: 1089.3157.
4.2.5. 3-Carboxypropyl 2,20,3,30,6,60-hexa-O-benzoyl-b-
D-lactoside (9). NaIO4 (0.61 g, 2.82 mmol) and RuCl3
(58.5 mg, 0.28 mmol) were added to a vigorously stirred
solution of compound 8 (1.46 g, 1.41 mmol) in CH2Cl2/
CH3CN/H2O. After 2 h, an additional amount of NaIO4
(0.61 g, 2.82 mmol) was added and the stirring was con-
tinued for another 2–3 h. The mixture was then diluted
with H2O and extracted with CH2Cl2. The organic layer
was dried over MgSO4 and then concentrated. The
resulting residues were purified by silica gel chromatog-
raphy (1:1, EtOAc/hexane) to give compound 9 (0.90 g,
60%), Rf = 0.21 (1:1, EtOAc/hexane); 1H NMR
(400 MHz, CDCl3): d 1.74–1.82 (m, H-b, 2H), 2.24–
2.27 (m, H-c, 2H), 3.48–3.53 (m, H-a, 1H), 3.64–3.70
(m, H-6a0, H-50, 2H), 3.80–3.86 (m, H-5, H-a, 2H),
4.2.7. Pent-4-enyl 2,3,4,6-tetra-O-benzyl-a-D-galactopyr-
anosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-galactopyranosyl-
(1!4)-2,3,6-tri-O-benzoyl-b-D-glucopyranoside (10).
A
solution of donor 8 (223.6 mg, 0.29 mmol), acceptor 2
˚
(200 mg, 0.19 mmol), and 4 A molecular sieve in CH2Cl2
(15 mL) was stirred 30 min at 0 °C. A TMSOTf was added
to this mixture dropwise (35 lL, 0.19 mmol). The reaction
mixture was stirred for 3 h at 0 °C, then filtered through a
Celite bed and concentrated. The residues were purified

S.-Y. Hsieh et al. / Carbohydrate Research 340 (2005) 49–57
55
by column chromatography (1:2, EtOAc/hexane) to give
compound 10 (192 mg, 75%). Rf = 0.24 (1:2, EtOAc/hex-
ane); 1H NMR (400 MHz, CDCl3): d 0.84–0.93 (m, H-b,
2H), 1.87–1.94 (m, H-c, 2H), 2.97 (dd, J = 5.0 Hz,
J = 8.2 Hz, H-60a, 1H), 3.31–3.36 (m, H-50, 1H), 3.41
(td, J = 6.8 Hz, J = 9.6 Hz, H-a, 1H), 3.65–3.69 (m, H-
500, 1H), 3.79 (td, J = 6.2 Hz, J = 9.6 Hz, H-a, 1H), 3.84–
3.89 (m, H-5, 1H), 3.90 (dd, J = 3.2 Hz, J = 10.4 Hz, H-
300, 1H), 3.95 (dd, J = 10.4 Hz, J = 2.4 Hz, H-300, 1H),
4.07 (br, H-400, 1H), 4.14–4.19 (m, H-600a, 1H), 4.18 (d,
J = 12.0 Hz, Bn), 4.24 (d, J = 9.6 Hz, H-4, 1H), 4.24–
4.27 (m, H-60b, 1H), 4.30 (d, J = 2.4 Hz, H-40, 1H), 4.44
(d, J = 11.2 Hz, Bn, 1H), 4.48 (dd, J = 4.4 Hz,
J = 12.0 Hz, H-6b, 1H), 4.55 (dd, J = 6.4 Hz,
J = 10.8 Hz, H-600b, 1H), 4.57 (s, Bn, 2H), 4.65 (d, J =
7.6 Hz, H-1, 1H), 4.64–4.79 (m, H-60b, H-e, Bn, 4H),
4.70 (d, J = 3.2 Hz, H-100, 1H), 4.81 (d, J = 10.8 Hz, Bn,
2H), 4.87 (d, J = 8.0 Hz, H-10, 1H), 5.03 (dd, J = 2.4 Hz,
J = 10.8 Hz, H-30, 1H), 5.36 (dd, J = 7.6 Hz, J = 9.6 Hz,
H-2, 1H), 5.59 (tdd, J = 6.4 Hz, J = 10.2 Hz, J =
17.0 Hz, H-d, 1H), 5.74 (dd, J = 8.0 Hz, J = 10.8 Hz,
H-20, 1H), 5.79 (t, J = 9.6 Hz, J = 9.6 Hz, H-3, 1H),
7.05–7.41 (m, Bn, Bz, 35H), 7.46–7.61 (m, Bz, 5H),
7.79–8.04 (m, Bz, 10H); 13C NMR (100 MHz, CDCl3): d
28.70, 29.94, 62.35, 62.74, 67.55, 69.47, 69.95, 70.08,
72.55, 72.86, 73.17, 73.23, 73.26, 73.49, 73.61, 74.65,
74.95, 75.12, 75.70, 76.06, 76.63, 77.43, 77.43, 79.32,
101.12, 101.35, 101.48, 115.01, 127.47, 127.51, 127.59,
127.65, 127.72, 127.74, 127.80, 127.83, 127.87, 128.13,
128.21, 128.24, 128.28, 128.40, 128.46, 128.49, 128.51,
128.61, 128.67, 128.69, 128.78, 128.99, 129.16, 129.18,
129.25, 129.54, 129.70, 129.79, 129.84, 129.93, 129.98,
130.00, 130.03, 130.07, 133.23, 133.27, 133.31, 133.37,
133.40, 137.95, 138.43, 138.72, 139.12, 139.17, 165.24,
165.46, 165.50, 165.83, 166.04, 166.69.
62.35, 62.67, 67.56, 68.89, 69.96, 70.08, 72.50, 72.86,
73.18, 73.18, 73.31, 73.50, 73.62, 74.64, 74.95, 75.12,
75.69, 76.05, 75.58, 79.32, 101.10, 101.38, 101.48,
127.48, 127.51, 127.60, 127.66, 127.83, 128.21, 128.25,
128.40, 128.47, 128.50, 128.52, 128.63, 128.79, 129.15,
129.25, 129.63, 129.80, 129.84, 129.99, 130.03, 130.08,
133.29, 133.34, 133.42, 138.42, 138.71, 139.12, 139.17,
165.25, 165.48, 165.83, 166.04, 166.70, 173.79. MS
(m/z) [M+Na]+: 1612.6.
4.2.9. 3-Methoxycarbonylpropyl a-D-galactopyranosyl-
(1!4)-2,3,6-tri-O-benzoyl-b-D-galactopyranosyl-(1!4)-
2,3,6-tri-O-benzoyl-b-D-glucopyranoside (13). The com-
pound 12 (350 mg, 0.22 mmol) was dissolved in a small
amount of EtOAc and MeOH (2 mL), and then
Pd(OH)2 (350 mg) was added. The reaction mixture
was purged by argon and then hydrogen, and stirred
at rt for 12 h. The reaction mixture was filtered through
Celite bed and concentrated. The resulting residue was
purified by column chromatography (1:1, EtOAc/hex-
32
D
ane) to give compound 13 (190 mg, 70%). ½aꢂ 55.843
(c 0.44, CHCl3), Rf = 0.39 (1:1, EtOAc/hexane + 10%
1
MeOH); H NMR (400 MHz, CDCl3): d 1.78–1.83 (m,
H-b, 2H), 2.26 (t, J = 7.2 Hz, H-c, 2H), 3.47–3.53 (m,
H-600a, H-600b, 2H), 3.50 (s, Me, 3H), 3.60 (ddd,
J = 3.6 Hz, J = 10.0 Hz, J = 13.6 Hz, H-a, 1H), 3.69
(dd, J = 3.0 Hz, J = 10.0 Hz, H-300, 1H), 3.76 (dd,
J = 3.6 Hz, J = 10.0 Hz, H-200, 1H), 3.83–3.96 (m, H-a,
H-5, 2H), 3.86 (td, J = 5.6 Hz, J = 6.0 Hz, J = 10.0 Hz,
H-50, 1H), 4.00 (dd, J = 0.8 Hz, J = 3.2 Hz, H-400, 1H),
4.02–4.08 (m, H-5, 1H), 4.05 (dd, J = 6.0 Hz,
J = 10.6 Hz, H-60a, 1H), 4.34–4.39 (m, H-4, H-40, 2H),
4.47 (dd, J = 5.6 Hz, J = 10.6 Hz, H-60b, 1H), 4.56 (dd,
J = 5.6 Hz, J = 12.0 Hz, H-6a, 1H), 4.71 (dd,
J = 2.0 Hz, J = 12.0 Hz, H-6b, 1H), 4.87–4.89 (m, H-
100, 1H), 4.91 (d, J = 8.0 Hz, H-1, 1H), 5.12 (d,
J = 8.0 Hz, H-10, 1H), 5.39 (dd, J = 8.0 Hz, J = 9.6 Hz,
H-2, 1H), 5.43 (dd, J = 2.8 Hz, J = 10.4 Hz, H-30, 1H),
5.73 (dd, J = 8.0 Hz, J = 10.4 Hz, H-20, 1H), 5.82 (t,
J = 9.6 Hz, J = 9.6 Hz, H-3, 1H), 7.25–7.31 (m, Bz,
19H), 7.94–8.12 (m, Bz, 11H); 13C NMR (100 MHz,
CDCl3): d 26.07, 30.82, 31.07, 52.01, 62.36, 63.88,
64.24, 69.99, 70.69, 71.08, 71.14, 71.89, 72.34, 73.82,
74.44, 74.69, 75.04, 75.27, 76.03, 78.30, 101.96, 102.39,
102.75, 129.66, 129.71, 129.75, 129.94, 130.35, 130.73,
130.78, 130.82, 130.98, 131.03, 131.06, 131.11,
131.37, 134.52, 134.67, 134.74, 166.98, 167.03, 167.36,
167.41, 167.50, 167.55, 175.47. HRMS (FAB)
calcd for C65H64O24 [M+Na]+: 1251.3685; found:
1251.3689.
4.2.8. 3-Methoxycarbonylpropyl 2,3,4,6-tetra-O-benzyl-
a-D-galactopyranosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-galac-
topyranosyl-(1!4)-2,3,6-tri-O-benzoyl-b-D-glucopyrano-
side (12). The procedure for the synthesis of
compound 12 is similar as described in the synthesis of
32
D
1
10. ½aꢂ 55.241 (c 1.14, CHCl3); H NMR (400 MHz,
CDCl3): d 3.24–3.29 (m, H-50, 1H), 3.35–3.48 (m, H-a,
1H), 3.41 (s, CH3, 3H), 3.58–3.61 (m, H-500, 1H), 3.71–
3.88 (m, H-a, H-5, H-200, H-300, 4H), 3.99 (br, H-400,
1H), 4.07–4.22 (m, H-600, H-4, H-60, H-40, 4H), 4.11 (d,
J = 12.4 Hz, Bn, 1H), 4.37 (d, J = 11.2 Hz, Bn, 1H),
4.39–4.48 (m, H-6, H-600, 2H), 4.48 (s, Bn, 2H), 4.56
(d, J = 7.2 Hz, H-1, 1H), 4.55–4.67 (m, H-6, Bn, 3H),
4.62 (d, J = 3.2 Hz, H-100, 1H), 4.73 (d, J = 10.8 Hz,
Bn, 1H), 4.79 (d, J = 7.6 Hz, H-10, 1H), 4.96 (dd,
J = 10.8 Hz, J = 2.0 Hz, H-30, 1H), 5.26 (dd,
J = 7.2 Hz, J = 9.6 Hz, H-2, 1H), 5.66 (dd, J = 7.6 Hz,
J = 10.8 Hz, H-20, 1H), 5.71 (t, J = 9.6 Hz, H-3, 1H),
7.00–7.53 (m, Bn, Bz, 30H), 7.72–7.95 (m, Bz, 15H);
13C NMR (100 MHz, CDCl3): d 24.90, 30.18, 51.55,
4.2.10. 3-Carboxypropyl a-D-galactopyranosyl-(1!4)-b-
D-galactopyranosyl-(1!4)-b-D-glucopyranoside (1). To
a mixture of compound 13 (150 mg, 0.12 mmol) in
CH2Cl2 (6 mL), water (3 mL) and CH3OH (9 mL) was
added 1 N NaOH (0.3 mL) and the reaction was stirred

56
S.-Y. Hsieh et al. / Carbohydrate Research 340 (2005) 49–57
at rt for 12 h. The reaction mixture was neutralized by
acidic resin, filtered, and then concentrated. The result-
ing residue was purified by column chromatography (1:1
MeOH/CH2Cl2) to give compound 1 (57 mg, 79%).
Rf = 0.12 (1:1, MeOH/CH2Cl2 twice); 1H NMR
(400 MHz, CDCl3): d 1.78–1.88 (m, H-b, 2H), 2.17–
2.22 (m, H-c, 2H), 3.23–3.27 (m, 1H), 3.50–3.94 (m,
17H), 3.98 (t, J = 3.6 Hz, 1H), 4.29 (t, J = 6.4 Hz, 1H),
4.2 (d, J = 8.0 Hz, 1H), 4.45 (d, J = 7.6 Hz, 1H), 4.79
(br, H-100, 1H). 13C NMR (100 MHz, CDCl3): d 25.86,
33.88, 60.22, 60.38, 60.84, 68.86, 69.36, 69.72, 69.84,
71.05, 71.27, 73.19, 73.36, 74.78, 74.78, 75.34, 78.27,
79.09, 101.13, 102.54, 103.96, 168.36.
Supplementary data
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.carres.
2004.10.024.
References
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4.2.11. 3-Carboxypropyl 2,3,4,6-tetra-O-acetyl-a-D-
galactopyranosyl-(1!4)-2,3,6-tri-O-acetyl-b-D-galacto-
pyranosyl-(1!4)-2,3,6-tri-O-acetyl-b-D-glucopyranoside
(14). To a solution of compound 1 (20 mg, 0.034 mmol)
in pyridine (0.2 mL) was added Ac2O (3.2 lL, 0.34 mmol)
and the reaction mixture was stirred at rt for overnight.
The solvent was evaporated in vacuo, and the resulting
residues were dissolved in EtOAc washed by 10% HCl,
water, saturated CuSO4(aq), water, saturated NaCO3(aq)
,
and brine. The organic layer was dried over MgSO4 and
concentrated. The residues were purified by silica gel
chromatography (1:1, EtOAc/hexane) to give compound
32
14 (21 mg, 60%). ½aꢂ 29.269 (c 0.33, CHCl3), Rf = 0.29
D
(1:1, EtOAc/hexane
+
10% MeOH); 1H NMR
(400 MHz, CDCl3): d 1.88–1.94 (m, H-b, 2H), 2.03 (s,
Ac, 3H), 2.10 (s, Ac, 6H), 2.12 (s, Ac, 3H), 2.12 (s, Ac,
3H), 2.13 (s, Ac, 3H), 2.16 (s, Ac, 6H), 2.18 (s, Ac, 6H),
2.20 (s, Ac, 3H), 2.39–2.43 (m, H-c, 2H), 3.63–3.68 (m,
H-a, 1H), 3.80–3.84 (m, H-5, 1H), 3.89–3.93 (m, H-40,
H-a, 1H), 4.05–4.08 (t, J = 6.4 Hz, H-4, 1H), 4.14–4.28
(m, H-5, H-6a0, H-600, 4H), 4.53 (dd, J = 7.4 Hz,
J = 11.0 Hz, H-6b0, 1H), 4.55–4.60 (m, H-3, H-500, H-6a,
3H), 4.68 (d, J = 8.0 Hz, H-10, 1H), 4.75 (d, J = 7.6 Hz,
H-1, 1H), 4.87–4.92 (m, H-20, 1H), 5.03 (dd, J = 2.6 Hz,
J = 10.6 Hz, H-6b, 1H), 5.12 (d, J = 3.2 Hz, H-100, 1H),
5.17 (dd, J = 7.6 Hz, J = 10.6 Hz, H-2, 1H), 5.23–5.29
(m, H-30, H-200, 2H), 5.46 (dd, J = 2.8 Hz, J = 10.8 Hz,
H-300, 1H), 5.61 (d, J = 2.8 Hz, H-400, 1H); 13C NMR
(100 MHz, CDCl3): d 20.67, 20.82, 20.93, 21.14, 21.34,
26.34, 61.98, 63.80, 63.93, 68.65, 69.08, 69.71, 70.04,
70.14, 71.09, 73.31, 73.69, 74.14, 74.23, 74.59, 77.72,
78.94, 99.30, 100.88, 101.92, 102.22, 171.36, 171.57,
172.05, 172.14, 172.30, 172.52, 172.61. HRMS (FAB)
Calcd for C42H58O28 [M+Na]+: 1033.3012; found:
1033.3016.
´
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Acknowledgements
The authors thank Academia Sinica, National Science
Council of Taiwan and National Taiwan Normal Uni-
versity for their financial support.

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