Ortho-Methylphenylthioglycosides as glycosyl building blocks for preactivation-based oligosaccharide synthesis

Article abstract of DOI:10.1016/j.carres.2013.11.009

Thioglycosides are widely used in orthogonal glycosylation, armed-disarmed chemoselective glycosylation, and preactivation-based glycosylation. Nevertheless, aglycon transfer occasionally occurred in the glycosylation process of thioglycosides. This probl

Full text of DOI:10.1016/j.carres.2013.11.009

Carbohydrate Research 384 (2014) 1–8
Contents lists available at ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
ortho-Methylphenylthioglycosides as glycosyl building blocks
for preactivation-based oligosaccharide synthesis
⇑
Peng Peng, De-Cai Xiong, Xin-Shan Ye
State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Xue Yuan Rd No. 38, Beijing 100191, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 29 October 2013
Received in revised form 13 November 2013
Accepted 14 November 2013
Available online 22 November 2013
Thioglycosides are widely used in orthogonal glycosylation, armed-disarmed chemoselective glycosyla-
tion, and preactivation-based glycosylation. Nevertheless, aglycon transfer occasionally occurred in the
glycosylation process of thioglycosides. This problem was also encountered in preactivation-based reac-
tions, which limited the applications of preactivation-based glycosylation to some extent. To tackle this
problem, sterically hindered aglycon ortho-methylphenylthioglycosides were introduced as glycosyl
building blocks. These thioglycosides prevented the aglycon transfer and enhanced the efficiency of gly-
cosyl coupling reactions, especially in the reactions of disarmed donors with armed acceptors. Moreover,
these thioglycosides were employed in preactivation-based one-pot oligosaccharide assembly.
Ó 2013 Elsevier Ltd. All rights reserved.
Keywords:
o-Methylphenylthioglycoside
Preactivation
Oligosaccharide
Aglycon transfer
Glycosylation
1. Introduction
Recently, in our group, the aglycon transfer was also encoun-
tered in the preactivation-based one-pot glycosylation protocol.26
Oligosaccharides and glycoconjugates have attracted much
attention due to their important roles in biological processes.1–3
However, understanding functions of carbohydrates is hampered
by the lack of general methods for the preparation of this class of
compounds. In the past decades, many advances on oligosaccha-
ride synthesis have been achieved, including solid-phase strategy,4
solution-phase protocol,5–7 and chemo-enzymatic method.8–10
Among these strategies, thioglycosides have been frequently used,
since they are convenient to prepare and stable in many functional
group transformations and glycosylations. On the other hand, be-
cause the sulfur atom in thioglycosides is able to react selectively
with thiophilic promoters, they are also effective glycosyl donors.
In one word, thioglycosides can serve as both donors and acceptors
in glycosylations.11 However, when thioglycosides are used as
glycosyl acceptors, the electrophilic intermediates resulted from
the activation of donors, could be also attacked by the sulfur atom
of acceptors. This phenomenon is known as the aglycon transfer. In
the previous studies, it was reported that sometimes the aglycon
transfer could be problematic when thioglycosides were used as
blocks.12–25 The aglycon transfer could affect both armed and
disarmed thioglycosides and destroy glycosylation products.24
Therefore, it may seriously reduce the efficiency of glycosidic bond
formation in a number of glycosylation strategies.
For example, as shown in Scheme 1, when the disarmed donor 1
was completely activated, which was followed by the coupling
with the armed acceptor 2, the coupled product disaccharide 3
was obtained in only 45% yield along with the recovery of donor
1 (15%). It was found that after the addition of acceptor 2, donor
1 which had been completely consumed regenerated. This phe-
nomenon happened especially in the glycosylations of armed
acceptors with disarmed donors. This regenerated donor 1 not only
reduced the coupling efficiency but also influenced the subsequent
glycosylation in one-pot strategy. The unfavorable regeneration of
donors is caused by the aglycon transfer of thioglycosides. In this
article, we intended to explore a new approach to overcome this
problem in the preactivation-based glycosylations.
2. Results and discussion
Many endeavors have been made to solve the aglycon transfer
problem. Boons and co-workers18 changed the protective groups
of building blocks. This conversion could address the problem of
aglycon transfer, but it needed extensive protective group manip-
ulations. Yu et al.17 observed that the higher reaction temperature
benefitted the aglycon transfer in some cases. Du and co-workers25
found that the aglycon transfer problem could be avoided by using
an inverse procedure (acceptors were added prior to donors). But
the inverse procedure was not suitable to the preactivation
protocol. Gildersleeve et al.24,27–29 installed sterically hindered
⇑
Corresponding author. Tel.: +86 10 82805736; fax: +86 10 82802724.
E-mail address: xinshan@bjmu.edu.cn (X.-S. Ye).
0008-6215/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.carres.2013.11.009

2
P. Peng et al. / Carbohydrate Research 384 (2014) 1–8
OH
OBz
O
BzO
BzO
O
BnO
BnO
STol
OBz
O
BzO
BzO
O
BnO
BzO
Ph2SO/Tf2O
2
O
1
+
BnO
STol
STol
BnO
BzO
BnO
45%
15%
1
3
CH3
Tol =
Scheme 1. Aglycon transfer occurred in preactivation-based glycosylations.
aglycon (2,6-dimethylphenylthioglycosides) to surmount aglycon
transfer process, for the steric hindrance of the leaving group in
acceptors could prevent the reaction with the intermediates pro-
duced from donors. We supposed this approach would be useful
in the preactivation protocol. However, it was reported that the
activation of 2,6-dimethylphenylthioglycoside donors needed
higher temperature (ꢀ15 °C).24 At this temperature, the active
intermediates derived from donors could be unstable in the preac-
tivation glycosylation process.30 To make sure the glycosyl donors
can be activated at low temperature, we choose o-methylphenyl-
thioglycosides as donors.31 This type of thioglycoside donors are
less sterically hindered, we want to investigate whether these thio-
glycosides can be used to prevent the aglycon transfer in glycosyl-
ation reactions.
We anticipated this leaving group would meet our require-
ments. Firstly, we chose the glycosylation of o-methylphenyl (oTol)
thioglycoside donor 4 and acceptor 5 as the model reaction. After
screening the reaction conditions, we found that it was not until
at ꢀ20 °C that the disarmed donor 4 was activated completely.
Luckily, at this temperature the activated intermediate of benzoy-
lated donor 4 could survive.30 In order to make the activated inter-
mediate stable, the reaction system was cooled down back to
ꢀ72 °C. Nearly one equivalent of armed acceptor 5 was then added
to the reaction mixture, affording the desired disaccharide 6 in 72%
yield with no donor 4 isolated (Scheme 2).
Since the aglycon transfer could affect armed thioglycosides as
well as disarmed thioglycosides,24 it was believed that thioglyco-
side acceptors would be the major factor in aglycon transfer. Thus,
various o-methylphenylthioglycosides were prepared as glycosyl
acceptors, and glycosylations were checked in pre-activation pro-
tocol. Next, an acceptor with a secondary hydroxyl group exposed
was tested toward glycosylation. In our experiments, using pre-
activation protocol, when the disarmed benzoylated p-methylphe-
nylthioglycoside donor 1 was reacted with the corresponding
armed thioglycoside acceptor 7 bearing a free hydroxyl group at
the C-4 position, no desired disaccharide product was formed.
Therefore, o-methylphenylthioglycoside 9 having the very similar
structure to compound 7 was used to react with donor 4. As our
anticipation, this reaction was carried out smoothly, providing
the disaccharide 10 in 68% isolated yield. In this reaction, there
was some amount of unreacted acceptor 9 recovered. When
1.5 equiv of donor was used, the acceptor was consumed com-
pletely, affording compound 10 in 80% isolated yield (Scheme 3).
Consequently, a series of acceptors were investigated under
preactivation-based conditions (Table 1). The acceptor 11 with a
C-3 hydroxyl group exposed was also glycosylated well with donor
4 to obtain disaccharide 12 in 93% yield (Table 1, entry 2). The dis-
armed benzoyl-protected acceptor 13 also coupled smoothly with
4 to produce disaccharide 14 in 92% isolated yield (Table 1, entry
3), whereas the analogue of 13 with ethylthio-substitute instead
of o-methylphenylthio-substitute did not react with the benzoylat-
ed thioglycoside donor.32 The glucosamine diol 15, underwent the
regioselective glycosylation with donor 4 to give the 1-4 linked
disaccharide 16 in 75% yield, this regioselectivity is well-known
in carbohydrate chemistry (Table 1, entry 4). The thiogalactoside
acceptor 17 with a secondary hydroxyl group exposed was reacted
with donor 4 to provide disaccharide 18 in 73% yield (Table 1, entry
5). The galactosamine donor 24 also coupled with acceptor 13,
affording disaccharide 25 in 75% yield (Table 1, entry 9). When
acceptor 19 was used, the coupling product 20 was isolated in
60% yield (Table 1, entry 6). It was found that acceptor 19 could
not undergo the reaction with the activated intermediate derived
from donor 4 until ꢀ40 °C and the coupling reaction was slow.
The glycosylation could also be influenced by the nucleophilicity
of acceptor. The acetylated acceptor 22 which was considered to
possess low nucleophilicity was examined. It was found that
acceptor 22 did not react with the activated intermediate until
ꢀ20 °C, and the disaccharide product was isolated in only 27% yield
(Table 1, entry 8). Similarly, another acceptor 21 with low nucleo-
philicity did not couple with the activated donor at all, regardless
of the promoters (Ph2SO/Tf2O or p-TolSCl/AgOTf) used, getting
the recovery of acceptor 21 (Table 1, entry 7). Although it was re-
ported that aglycon transfer could also occur in the disarmed thio-
glycoside cases,24 we did not observe this phenomenon in these
reactions. Why did some disarmed acceptors not react well with
disarmed donors in some cases? Our results indicated that the
inefficient glycosylation might be not affected by aglycon transfer,
but could be probably attributed to the low nucleophilicity of hy-
droxyl in acceptors toward the unreactive intermediates derived
from donors. It was noted that in all the reactions mentioned
OH
OBz
O
BzO
BzO
O
BnO
BnO
SoTol
OBz
O
BzO
BzO
O
BnO
BzO
BnO
BnO
a
5
O
SoTol
CH3
SoTol
BzO
BnO
4
6
72%
oTol =
Scheme 2. Reagents and conditions: (a) Ph2SO, Tf2O, 4 Å molecular sieves, ꢀ72 °C to ꢀ20 °C, then cooled to ꢀ72 °C.

P. Peng et al. / Carbohydrate Research 384 (2014) 1–8
3
OBn
O
HO
STol
BnO
OBz
OBz
O
OBn
BzO
BzO
BzO
BzO
BnO
O
O
Ph2SO,Tf2O
7
O
STol
STol
BnO
BzO
DCM, 4Å MS
BzO
BnO
1
8
0%
OBn
O
HO
BnO
SoTol
OBz
OBn
BzO
BzO
BzO
BzO
OBz
O
BnO
O
O
Ph2SO,Tf2O
9
O
SoTol
SoTol
BnO
BzO
BzO
4
BnO
DCM, 4Å MS
oTol =
10
68%a (80%b)
CH3
Tol =
CH3
Scheme 3. Conditions: (a) donor/acceptor = 1.1:1; (b) donor/acceptor = 1.5:1.
above, the regenerated donor and its anomerized product were not
isolated. That means the aglycon transfer phenomenon was
avoided in the preactivation-based glycosylation process.
To investigate the scope of o-methylphenylthioglycosides in
glycosylations, the o-methylphenylthioglycoside donors with high-
er reactivity were prepared. As expected, both the armed donor 26
and the moderate donor 28 were activated quickly at ꢀ72 °C, and
the coupled products were obtained in good yields (Table 1, entries
10 and 11). It is noteworthy that the coupling of 26 and 21 yielded
(CH2Cl2) was distilled over calcium hydride (CaH2). All reactions
were performed in flame-dried modified Schlenk (Kjeldahl shape)
flasks fitted with a glass stopper or rubber septa under a positive
pressure of argon or nitrogen. Analytical TLC was performed on sil-
ica gel 60-F254 precoated on aluminum plates (E. Merck), with
detection by UV (254 nm) and/or by staining with acidic ceric
ammonium molybdate. Solvents were evaporated under reduced
pressure and below 35 °C (bath). Organic solutions of crude prod-
ucts were dried over anhydrous Na2SO4. Column chromatography
was performed employing silica gel (200–300 mesh). 1H NMR
spectra were recorded on Advance DRX Bruker-400 spectrometers
at 25 °C. Chemical shifts (in ppm) were referenced to tetramethyl-
silane (d = 0 ppm) in deuterated chloroform. 13C NMR spectra were
obtained by using the same NMR spectrometers and were cali-
brated with CDCl3 (d = 77.00 ppm). High-resolution mass spectra
were recorded on a Bruker APEX IV. Optical rotations were mea-
sured with an AA-10R automatic polarimeter.
the exclusive a-linked product 27 due to the anomeric effect. These
reactions needed to be quenched at ꢀ72 °C. Otherwise, the formed
disaccharide products would be decomposed by the unfavorable S-
thiophenyl sulfonium by-product33 from Ph2SO, whereas this
problem did not occur in the examples of disarmed donors men-
tioned above. The reason might be that S-thiophenyl sulfonium
also decomposed when the preactivation temperature was raised.
The next issue was to determine if o-methylphenylthioglycosides
could be applied to preactivation-based iterative one-pot oligosac-
charide synthesis. Indeed, they worked well. As exemplified in
Scheme 4, glycosyl donor 4 coupled with acceptor 13 very smoothly
when promoted by Ph2SO/Tf2O. After the glycosyl coupling reaction
was completed, the newly formed disaccharide without isolation
was activated again by the same promoter system, which was fol-
lowed by the addition of acceptor 30, providing the final trisaccharide
31 in 76% isolated yield with good stereoselectivity.
4.2. General procedure for preactivation-based glycosylation
Method A: A solution of donor (50
lmol, 1.5 equiv), Ph2SO
(55 mol, 1.6 equiv), and activated 4 Å powdered molecular sieves
l
in dichloromethane (2 mL) was stirred at room temperature under
an argon atmosphere for 30 min. Then the mixture was cooled to
ꢀ72 °C and Tf2O (55
lmol, 1.6 equiv) was added. The temperature
was raised to ꢀ20 °C slowly. The reaction mixture was stirred at
this temperature for 5 min and then cooled back to ꢀ72 °C. Subse-
3. Conclusions
quently, acceptor (33 lmol, 1.0 equiv) was added. The reaction was
further stirred for 15 min and warmed gradually to room temper-
ature. The reaction was quenched by triethylamine (0.2 mL) and
the precipitated was filtered off through a pad of Celite. The filtrate
was concentrated and the residue was purified by column chroma-
In summary, a series of sterically hindered o-methylphenylthio-
glycosides working as building blocks for oligosaccharide synthesis
were designed and synthesized for preactivation-based glycosylation
protocol. These thioglycosides were able to efficiently prevent the
aglycon transfer, thus enhancing the efficiency of glycosyl coupling
reactions. Thesethioglycosidesovercomesomelimitationsofthecon-
ventional thioglycosides currently used in the preactivation protocol
and can be employed in iterative one-pot oligosaccharide assembly.
tography on silica gel. Method B: A solution of donor (34
lmol,
1.2 equiv), Ph2SO (38 mol, 1.3 equiv) and activated 4 Å powdered
l
molecular sieves in dichloromethane (2 mL) was stirred at room
temperature under an argon atmosphere for 30 min. The mixture
was cooled to ꢀ72 °C and Tf2O (38
After the TLC detection indicated that donor was completely con-
sumed, acceptor (29 mol, 1.0 equiv) was added. The reaction
lmol, 1.3 equiv) was added.
4. Experimental
4.1. General
l
was further stirred for 30 min and quenched by triethylamine
(0.2 mL). The precipitated was filtered off through a pad of Celite.
The filtrate was concentrated and the residue was purified by col-
umn chromatography on silica gel.
All chemicals were purchased as reagent grade and used with-
out further purification, unless otherwise noted. Dichloromethane

4
P. Peng et al. / Carbohydrate Research 384 (2014) 1–8
Table 1
Glycosylations with o-methylphenylthioglycosides (o-Tol) as building blocks
Entry
Donor
Acceptor
Product
Yield (%)
80a
1
2
3
93a
92a
4
5
75a
73a
6
60a
7
8
0
27a
9
75a
10
85b
11
77b
a
Donor/acceptor = 1.5:1.
Donor/acceptor = 1.2:1 and quenched at ꢀ72 °C.
b

P. Peng et al. / Carbohydrate Research 384 (2014) 1–8
5
OH
OH
O
BzO
BzO
O
OBz
O
BzO
BzO
BzO
SoTol
BzO
OMe
BzO
BzO
Ph2SO (1.1 eq)
O
30 (1.1 eq)
Tf2O (1.6 eq)
13 (1.0 eq) Tf2O (1.1 eq)
OBz
O
BzO
BzO
BzO
BzO
BzO
O
O
SoTol
BzO
BzO
BzO
O
BzO
4 (1.5 eq)
Ph2SO (1.6 eq)
31
76 %
-72oC -20oC
o
-72 C
-72oC
rt
BzO
OMe
Scheme 4. Pre-activation based one-pot assembly of trisaccharide 31 using o-methylphenylthioglycosides as building blocks.
4.2.1. p-Tolyl 6-O-(2,3,4,6-tetra-O-benzoyl-b-
D
-galactopyrano
4.2.3. o-Tolyl 4-O-(2,3,4,6-tetra-O-benzoyl-b-D-galactopyran
syl)-2,3,4-tri-O-benzyl-1-thio-b- -glucopyranoside (3)
D
osyl)-2,3,6-tri-O-benzyl-1-thio-b- -glucopyranoside (10)
D
Compound 3 (13.0 mg, 45% yield as a semisolid) was prepared
according to the general procedure (Method B) from donor 1
Compound 10 (33.0 mg, 80% yield as a semisolid) was prepared
according to the general procedure (Method A) from donor 4
(20.0 mg, 28
purified by column chromatography (toluene/acetonitrile = 30:1).
+30.3° (c 1.19 in CHCl3); 1H NMR (400 MHz, CDCl3): d 8.10 (d,
l
mol) and acceptor 2 (14.3 mg, 25
l
mol), and was
(38.0 mg, 54 lmol) and acceptor 9 (20.0 mg, 36 lmol), and was
purified by column chromatography (toluene/acetonitrile = 30:1).
½
a 2D5
ꢁ
½
a 2D5
ꢁ
ꢀ4.5° (c 2.65 in CHCl3); 1H NMR (400 MHz, CDCl3): d 8.02
2H, J = 8.4 Hz), 8.03 (d, 2H, J = 8.4 Hz), 7.84 (d, 2H, J = 8.4 Hz), 7.84
(d, 2H, J = 8.4 Hz), 7.22–7.62 (m, 31H), 7.15 (d, 2H, J = 8.0 Hz),
7.10–7.12 (m, 2H), 5.95 (d, 1H, J = 3.2 Hz, H-40), 5.85 (dd, 1H,
J = 8.0, 10.4 Hz, H-20), 5.55 (dd, 1H, J = 3.6, 10.4 Hz, H-30), 4.94
(d, 1H, J = 8.0 Hz), 4.85 (d, 1H, J = 10.0 Hz, PhCH2), 4.82 (d, 1H,
J = 10.0 Hz, PhCH2), 4.73 (d, 1H, J = 11.2 Hz, PhCH2), 4.64–4.69
(m, 2H, H-6a, PhCH2), 4.60 (1H, J = 10.8 Hz, PhCH2), 4.55 (d, 1H,
J = 9.6 Hz, H-1), 4.45 (d, 1H, J = 10.8 Hz, PhCH2), 4.42 (dd, 1H,
J = 6.8, 11.2 Hz, H-6b), 4.19–4.22 (m, 2H, H-5, H-6a0), 3.90 (dd,
1H, J = 4.4, 11.2 Hz, H-6b0), 3.59 (t, 1H, J = 8.8 Hz, H-3), 3.42–
3.48 (m, 2H, H-4, H-5), 3.37 (t, 1H, J = 9.6 Hz, H-2), 2.26 (s, 3H,
Me). 13C NMR (100 MHz, CDCl3): d 165.98, 165.57, 165.53,
165.11, 138.33, 138.72, 137.93, 137.81, 133.51, 133.22, 133.07,
132.71, 130.02, 129.87, 129.81, 129.77, 129.57, 129.45, 129.29,
129.09, 128.80, 128.62, 128.45, 128.39, 128.37, 128.31, 128.26,
128.19, 127.80, 127.69, 127.63, 101.25, 87.57, 86.56, 78.98,
77.41, 75.62, 75.31, 74.87, 71.82, 71.29, 69.75, 68.15, 67.85,
61.92, 21.03. Calcd for C68H62NaO14S [M+Na]+ 1157.3753. Found:
1157.3741.
(dd, 2H, J = 1.6, 8.8 Hz), 7.92 (dd, 2H, J = 1.2, 8.4 Hz), 7.87 (dd, 2H,
J = 1.2, 8.4 Hz) 7.76 (dd, 2H, J = 1.2, 8.4 Hz), 7.19–7.56 (m, 35 H),
7.11–7.14 (m, 1H), 5.88 (d, 1H, J = 2.8 Hz, H-40), 5.73 (dd, 1H,
J = 8.0, 10.4 Hz, H-20), 5.43 (dd, 1H, J = 3.6, 10.6 Hz, H-30), 5.25 (d,
1H, J = 10.8 Hz, PhCH2), 4.99 (d, 1H, J = 8.0 Hz, H-10), 4.87 (d, 1H,
J = 10.8 Hz, PhCH2), 4.85 (d, 1H, J = 10.4 Hz, PhCH2), 4.79 (d, 1H,
J = 10.4 Hz, PhCH2), 4.71 (d, 1H, J = 12.0 Hz, PhCH2), 4.57 (d, 1H,
J = 10.0 Hz, H-1), 4.39–4.41 (m, 2H, H-6a0, PhCH2), 4.14–4.24 (m,
2H, H-6b0, H-4), 4.00 (t, 1H, J = 6.8 Hz, H-50), 3.67–3.71 (m, 2H, H-
3, H-6a), 3.51–3.60 (m, 2H, H-6b, H-2), 3.25–3.28 (dd, 1H, J = 2.0,
10.0 Hz, H-5), 2.41 (s, 3H, Me). 13C NMR (100 MHz, CDCl3): d
165.79, 165.44, 165.38, 164.89, 139.18, 138.91, 138.03, 137.99,
133.68, 133.39, 133.19, 131.75, 130.07, 129.78, 129.69, 129.62,
129.46, 129.00, 128.75, 128.59, 128.52, 128.47, 128.42, 128.24,
128.20, 128.15, 128.07, 128.00, 127.69, 127.33, 127.28, 126.49,
100.40, 87.72, 84.56, 80.60, 78.39, 76.43, 75.63, 75.39, 73.52,
71.78, 71.08, 70.30, 67.84, 61.37, 20.91. HRMS (ESI) Calcd for C68-
H66NO14S [M+NH4]+ 1152.4199. Found: 1152.4181. Calcd for C68-
H62NaO14S [M+Na]+ 1157.3753. Found: 1157.3761.
4.2.2. o-Tolyl 6-O-(2,3,4,6-tetra-O-benzoyl-b-
D
-galactopyrano
4.2.4. o-Tolyl 3-O-(2,3,4,6-tetra-O-benzoyl-b-
D
-galactopyrano
syl)-2,3,4-tri-O-benzyl-1-thio-b- -glucopyranoside (6)
D
syl)-2-O-benzyl-4,6-O-benzylidene-1-thio-b-D-glucopyranoside
Compound 6 (21.0 mg, 72% yield as a semisolid) was prepared
according to the general procedure (Method A) from donor 4
(12)
Compound 12 (31.2 mg, 93% yield as a semisolid) was prepared
according to the general procedure (Method A) from donor 4
(34.0 mg, 48 lmol) and acceptor 11 (15.0 mg, 32 lmol), and was
(20.0 mg, 28
purified by column chromatography (toluene/acetonitrile = 30:1).
+37.7° (c 1.06 in CHCl3); 1H NMR (400 MHz, CDCl3): d 8.09
lmol) and acceptor 5 (14.3 mg, 25 lmol), and was
½
a 2D5
ꢁ
purified by column chromatography (petroleum ether/ethyl ace-
(d, 2H, J = 7.6 Hz), 8.03 (d, 2H, J = 7.6 Hz), 7.78–7.83 (m, 4H), 7.66
(d, 1H, J = 7.6 Hz), 7.61 (t, 1H, J = 7.2 Hz), 7.55 (t, 1H, J = 7.2 Hz),
7.40–7.49 (m, 6H), 7.12–7.37 (m, 29H), 5.95 (d, 1H, J = 2.8 Hz, H-
40), 5.81 (dd, 1H, J = 8.0, 10.4 Hz, H-20), 5.50 (dd, 1H, J = 3.2,
10.4 Hz, H-30), 4.89 (d, 1H, J = 10.8 Hz, PhCH2), 4.86 (d, 1H,
J = 8.4 Hz, H-10), 4.85 (d, 1H, J = 10.8 Hz, PhCH2), 4.75 (d, 1H,
J = 10.8 Hz, PhCH2), 4.73 (d, 1H, J = 10.4 Hz, PhCH2), 4.62–4.67 (m,
3H, H-1, H-6a0, PhCH2), 4.47 (d, 1H, J = 10.8 Hz, PhCH2), 4.39 (dd,
1H, J = 6.8, 11.6 Hz, H-6b0), 4.14–4.17 (m, 2H, H-50, H-6a), 3.88
(dd, 1H, J = 4.8, 11.2 Hz, H-6b), 3.61 (t, 1H, J = 8.4 Hz), 3.42–3.51
(m, 3H), 2.43 (s, 3H, Me). 13C NMR (100 MHz, CDCl3): d 165.92,
165.53, 165.47, 165.07, 139.14, 138.28, 137.88, 137.71, 133.47,
133.32, 133.19, 133.01, 131.86, 130.23, 129.97, 129.75, 129.71,
129.61, 129.38, 129.23, 129.01, 128.73, 128.56, 128.41, 128.37,
128.33, 128.25, 128.21, 128.13, 127.80, 127.71, 127.60, 126.88,
101.07, 87.24, 86.54, 80.90, 79.04, 77.37, 75.58, 75.47, 74.86,
71.71, 71.21, 69.68, 68.07, 67.80, 61.93, 20.96. HRMS (ESI) Calcd
for C68H66NO14S [M+NH4]+ 1152.4199. Found: 1152.4188.
tate = 3:1). ½a 2D5
ꢁ
+33.7° (c 2.85 in CHCl3); 1H NMR (400 MHz,
CDCl3): d 8.05 (d, 2H, J = 7.2 Hz), 7.95 (d, 2H, J = 7.2 Hz), 7.73–
7.80 (m, 3H), 7.50–7.60 (m, 5H), 7.37–7.47 (m, 9H), 7.10–7.30
(m, 19H), 5.93 (d, 1H, J = 3.2 Hz, H-40), 5.88 (dd, 1H, J = 8.4,
10.4 Hz, H-20), 5.61 (s, 1H, PhCH), 5.54 (dd, 1H, J = 3.6, 10.4 Hz, H-
30), 5.25 (d, 1H, J = 8.0 Hz, H-10), 4.77 (d, 1H, J = 10.4 Hz, PhCH2),
4.72 (d, 1H, J = 11.2 Hz, PhCH2), 4.69 (d, 1H, J = 10.0 Hz, H-10),
4.48 (dd, 1H, J = 6.4, 11.2 Hz, H-6a0), 4.31–4.39 (m, 2H, H-6b0, H-
6a), 4.17 (t, 1H, J =8.8 Hz, H-3), 4.03 (t, 1H, J = 6.8 Hz, H-50), 3.84
(t, 1H, J = 9.6 Hz, H-4), 3.79 (t, 1H, J = 10.4 Hz, H-6b), 3.62 (dd,
1H, J = 8.4, 9.6 Hz, H-2), 3.40–3.46 (dt, 1H, J = 4.8, 9.6 Hz, H-5).
2.32 (s, 3H, Me). 13C NMR (100 MHz, CDCl3): d 165.77, 165.57,
165.46, 165.32, 139.38, 137.78, 137.12, 133.46, 133.19, 133.10,
131.80, 130.28, 129.94, 129.79, 129.72, 129.65, 129.34, 129.12,
129.06, 128.72, 128.58, 128.39, 128.27, 128.22, 128.19, 127.65,
127.56, 126.59, 126.00, 124.77, 101.30, 100.72, 88.36, 81.95,
80.65, 79.16, 75.65, 71.98, 71.07, 70.34, 70.18, 68.64, 67.95,
61.41, 20.84. HRMS (ESI) Calcd for
C
61H58NO14S1 [M+NH4]+

6
P. Peng et al. / Carbohydrate Research 384 (2014) 1–8
1060.3573. Found: 1060.3541. Calcd for C61H54NaO14S1 [M+K]+
1081.2860. Found: 1081.2822.
J = 9.2 Hz, H-2), 3.61–3.64 (m, 1H), 3.49–3.55 (m, 2H), 2.28 (s, 3H,
Me). 13C NMR (100 MHz, CDCl3):
165.89, 165.53, 165.44,
d
165.24, 138.79, 138.33, 138.09, 137.90, 134.23, 133.59, 133.35,
133.30, 133.19, 131.04, 129.90, 129.85, 129.71, 129.63, 129.27,
129.00, 128.96, 128.64, 128.51, 128.38, 128.31, 128.26, 128.23,
127.73, 127.66, 127.63, 127.60, 127.58, 127.46, 127.34, 126.80,
126.49, 101.81, 87.74, 82.59, 77.63, 77.55, 76.42, 75.18, 74.85,
73.42, 71.52, 71.47, 70.23, 69.30, 68.26, 61.96, 20.75. HRMS (ESI)
Calcd for C68H62NaO14S [M+Na]+: 1157.3717. Found: 1157.3753.
Calcd for C68H66NO14S [M+NH4]+: 1152.4228. Found: 1152.4198.
4.2.5. o-Tolyl 6-O-(2,3,4,6-tetra-O-benzoyl-b-
D-galactopyrano
syl)-2,3,4-tri-O-benzoyl-1-thio-b- -glucopyranoside (14)
D
Compound 14 (36.0 mg, 92% yield as foams) was prepared
according to the general procedure (Method A) from donor 4
(35.2 mg, 50 lmol) and acceptor 13 (20.0 mg, 33 lmol), and was
purified by column chromatography (petroleum ether/ethyl ace-
tate = 3:1). ½a 2D5
ꢁ
+ 58.3° (c 1.72 in CHCl3); 1H NMR (400 MHz,
CDCl3): d 8.03–8.07 (m, 4H), 7.75–7.93 (m, 10H), 7.17–7.61 (m,
28H), 5.96 (d, 1H, J = 2.8 Hz, H-40), 5.76–5.82 (m, 2H, H-20, H-3),
5.51 (dd, 1H, J = 3.2, 10.4 Hz, H-30), 5.44 (t, 1H, J = 9.6 Hz, H-2),
5.33 (t, 1H, J = 9.6 Hz, H-4), 4.95 (d, 1H, J = 8.0 Hz, H-10), 4.94 (d,
1H, J = 10.0 Hz, H-1), 4.57 (dd, 1H, J = 6.4, 11.2 Hz, H-6a0), 4.38
(dd, 1H, J = 6.4, 11.6 Hz, H-6b0), 4.22 (t, 1H, J = 6.8 Hz, H-50), 3.99–
4.06 (m, 3H, H-5, H-6a, H-6b), 2.25 (s, 3H, Me). 13C NMR
4.2.8. o-Tolyl 2-O-(2,3,4,6-tetra-O-benzoyl-b-
osyl)-3-O-benzoyl-4,6-O-benzylidene-1-thio-b-
ranoside (20)
Compound 20 (28.0 mg, 60% yield as a semisolid) was prepared
according to the general procedure (Method A) from donor 4
(44.0 mg, 63 lmol) and acceptor 19 (20.0 mg, 42 lmol), and was
D
-galactopyran
-galactopy
D
(100 MHz, CDCl3):
d
165.94, 165.65, 165.53, 165.50, 165.29,
purified by column chromatography (petroleum ether/ethyl ace-
164.97, 140.20, 133.52, 133.48, 133.30, 133.22, 133.16, 133.10,
133.02, 131.86, 130.36, 129.99, 129.78, 129.68, 129.37, 129.32,
129.14, 129.04, 128.77, 128.59, 128.52, 128.47, 128.40, 128.34,
128.29, 128.25, 128.23, 126.97, 101.25, 86.38, 78.64, 74.08, 71.75,
71.42, 70.60, 69.61, 69.36, 68.13, 68.10, 61.95, 20.93. HRMS (ESI)
Calcd for C68H60NO17S [M+NH4]+: 1194.3577. Found: 1194.3541.
Calcd for C68H56NaO17S [M+Na]+: 1199.3130. Found: 1199.3101.
tate = 1.5:1). ½a D25
ꢁ
+60.2° (c 2.33 in CHCl3); 1H NMR (400 MHz,
CDCl3): d 8.06 (d, 2H, J = 1.2, 8.0 Hz), 7.77–8.02 (m, 4H), 7.89 (d,
1H, J = 7.2 Hz), 7.35–7.70 (m, 21H), 7.15–7.23 (m, 6H), 7.07–7.09
(m, 1H), 5.93 (d, 1H, J = 3.2 Hz, H-40), 5.76 (dd, 1H, J = 8.0, 10.4 Hz,
H-20), 5.47 (s, 1H, PhCH), 5.35 (dd, 1H, J= 3.2, 10.4 Hz, H-30), 5.17 (d,
1H, J = 8.0 Hz, H-10), 5.13 (dd, 1H, J = 3.6, 9.6 Hz, H-3), 4.78 (d, 1H,
J = 9.6 Hz, H-1), 4.64 (t, 1H, J = 9.6 Hz, H-2), 4.49 (d, 1H, J = 3.2 Hz,
H-4), 4.38–4.43 (m, 2H, H-6a0, H-6a), 4.28 (dd, 1H, J = 8.0, 11.2 Hz,
H-6b0), 4.20 (t, 1H, J = 6.8 Hz, H-50), 3.99 (dd, 1H, J = 1.2, 10.4 Hz,
H-6b), 3.56 (s, 1H, H-5), 2.52 (s, 3H, Me). 13C NMR (100 MHz, CDCl3):
d 165.99, 165.50, 165.47, 165.35, 165.13, 139.19, 137.67, 133.71,
133.60, 133.48, 133.18, 132.92, 131.89, 130.25, 129.95, 129.76,
129.67, 129.48, 129.38, 129.27, 129.09, 128.97, 128.95, 128.71,
128.67, 128.56, 128.44, 128.19, 128.16, 128.12, 127.04, 126.47,
126.32, 100.92, 100.69, 85.83, 76.79, 73.71, 71.85, 70.94, 70.83,
69.99, 69.53, 69.10, 67.63, 61.20, 21.01. HRMS (ESI) Calcd for C61H56-
NO15S [M+NH4]+: 1074.3366. Found: 1074.3365.
4.2.6. o-Tolyl 4-O-(2,3,4,6-tetra-O-benzoyl-b-D-galactopyrano
syl)-2-N-phthalimido-6-O-benzyl-2-deoxy-1-thio-b-D-glucop
yranoside (16)
Compound 16 (33.0 mg, 75% yield as a semisolid) was prepared
according to the general procedure (Method A) from donor 4
(41.8 mg, 60 lmol) and acceptor 15 (20.0 mg, 40 lmol), and was
purified by column chromatography (petroleum ether/ethyl ace-
tate = 1.5:1). ½a D25
ꢁ
+ 85.2° (c 1.55 in CHCl3); 1H NMR (400 MHz,
CDCl3): d 7.96–8.05 (m, 6H), 7.89–7.91 (m, 1H), 7.70–7.82 (m,
5H), 7.16–7.63 (m, 40H), 7.06–7.10 (m, 2H), 6.96–7.00 (m, 1H),
5.94 (d, 1H, J = 3.2 Hz, H-40), 5.83 (dd, 1H, J = 8.0, 10.4 Hz, H-20),
5.56 (dd. 1H, J = 3.6, 10.4 Hz, H-30), 5.52 (d, 1H, J = 10.8 Hz, H-1),
4.92 (d, 1H, J = 8.0 Hz, H-10), 4.59–4.69 (m, 2H, H-3, H-6a0), 4.37–
4.43 (m, 2H, H-2, –OH), 4.31–4.35 (m, 2H, H-50, H-6b0), 4.22 (d,
1H, J = 12.0 Hz, PhCH2), 4.14 (d, 1H, 12.4 Hz, PhCH2), 3,86 (t, 1H,
J = 9.6 Hz, H-4), 3.62–3.65 (m, 1H, H-5), 3.44–3.51 (m, 2H, H-6a,
H-6b), 2.19 (s, 3H, Me). 13C NMR (100 MHz, CDCl3): d 168.12,
167.42, 166.13, 165.40, 165.34, 164.95, 140.06, 138.25, 134.01,
133.72, 133.57, 133.35, 133.25, 133.01, 132.02, 131.85, 131.70,
130.11, 129.98, 129.87, 129.84, 129.74, 129.00, 128.92, 128.67,
128.55, 128.46, 128.32, 128.30, 127.87, 127.58, 127.44, 126.51,
123.60, 123.20, 101.96, 83.83, 82.43, 77.83, 73.02, 72.34, 71.40,
70.85, 69.53, 68.18, 68.02, 62.57, 55.26, 20.82. HRMS (ESI) Calcd
for C62H57N2O15S [M+NH4]+: 1101.3488. Found: 1101.3474.
4.2.9. o-Tolyl 3-O-(2,3,4,6-tetra-O-benzoyl-b-D-galactopyran
osyl)-2,4,6-tri-O-acetyl-1-thio-b- -galactopyranoside (23)
D
Compound 23 (13.0 mg, 27% yield as a semisolid) was prepared
according to the general procedure (Method A) from donor 4
(51.0 mg, 63 lmol) and acceptor 22 (20.0 mg, 48 lmol), and was
purified by column chromatography (petroleum ether/ethyl ace-
tate = 1:1). ½a 2D5
ꢁ
+63.9° (c 1.66 in CHCl3); 1H NMR (400 MHz,
CDCl3): d 8.12 (d, 2H, J = 7.6 Hz), 8.02 (d, 2H, J = 7.6 Hz), 7.92 (d,
2H, J = 7.6 Hz), 7.76 (d, 2H, J = 7.6 Hz), 7.63 (t, 1H, J = 7.6 Hz),
7.49–7.56 (m, 5H), 7.36–7.44 (m, 5H), 7.00–7.23 (m, 5H), 5.94 (d,
1H, J = 3.2 Hz, H-40), 5.70 (dd, 1H, J = 8.0, 10.8 Hz, H-20), 5.63 (d,
1H, J = 3.2 Hz, H-4), 5.57 (dd, 1H, J = 3.2, 10.4 Hz, H-30), 5.27 (t,
1H, J = 9.6 Hz, H-2), 4.94 (d, 1H, J = 7.6 Hz, H-10), 4.70 (dd, 1H,
J = 6.4, 11.2 Hz, H-6a0), 4.51 (d, 1H, J = 10.0 Hz, H-1), 4.37 (dd, 1H,
J = 6.4, 10.8 Hz, H-6b0), 4.29 (t, 1H, J = 6.4 Hz, H-50), 4.06–4.14 (m,
2H, H-6a, H-6b), 3.91 (dd, 1H, J = 3.6, 9.6 Hz, H-3), 3.76 (t, 1H,
J = 6.8 Hz, H-5), 2.32 (s, 3H, Me), 2.23 (s, 3H, OAc), 2.03 (s, 3H,
OAc), 1.59 (s, 3H, OAc). 13C NMR (100 MHz, CDCl3): d 170.39,
169.88, 168.79, 165.98, 165.58, 165.44, 164.74, 139.66, 133.62,
133.30, 133.23, 132.10, 130.22, 130.12, 129.76, 129.44, 129.36,
129.03, 128.65, 128.50, 128.32, 128.29, 127.86, 126.47, 101.62,
87.16, 78.39, 75.14, 71.39, 71.29, 69.87, 69.36, 68.83, 67.73,
4.2.7. o-Tolyl 3-O-(2,3,4,6-tetra-O-benzoyl-b-
osyl)-2,4,6-tri-O-benzyl-1-thio-b- -galactopyranoside (18)
Compound 18 (15.2 mg, 73% yield as a semisolid) was prepared
according to the general procedure (Method A) from donor 4
(20.0 mg, 28 lmol) and acceptor 17 (10.0 mg, 18 lmol), and was
D-galactopyran
D
purified by column chromatography (petroleum ether/ethyl ace-
tate = 4:1). ½a 2D5
ꢁ
+38.2° (c 1.52 in CHCl3); 1H NMR (400 MHz,
CDCl3): d 8.03 (d, 2H, J = 8.4 Hz), 7.98 (d, 2H, J = 8.4 Hz), 7.84 (d,
2H, J = 8.4 Hz), 7.76 (d, 2H, J = 8.4 Hz), 7.07–7.58 (m, 33 H), 6.95–
6.97 (m, 1H), 6.00 (m, 2H, H-20, H-40), 5.63 (dd, 1H, J = 3.6,
10.8 Hz, H-30), 5.32 (d, 1H, J = 7.6 Hz, H-10), 5.22 (d, 1H,
J = 11.2 Hz, PhCH2), 4.73 (d, 1H, J = 11.2 Hz, PhCH2), 4.69 (dd, 1H,
J = 6.8, 11.2 Hz), 4.61 (d, 1H, J = 10.4 Hz), 4.53 (d, 1H, J = 9.6 Hz,
H-1), 4.39–4.47 (m, 4H), 4.27 (t, 1H, J = 6.4 Hz), 4.10 (d, 1H,
J = 2.8 Hz, H-4), 3.97 (dd, 1H, J = 2.8, 9.2 Hz, H-3), 3.86 (t, 1H,
62.68, 61.75, 20.78, 20.68, 20.18. HRMS (ESI) Calcd for C53H54NO17
S
[M + NH4]+: 1008.3112. Found: 1008.3099.
4.2.10. o-Tolyl 6-O-(2-N-(2,2,2-trichloroethoxylcarbonylamino)-
3,4,6-tri-O-acetyl-2-deoxy-b- -galactopyranosyl)-2,3,4-tri-O-
benzoyl-1-thio-b- -glucopyranoside (25)
D
D
Compound 25 (20.0 mg, 75% yield as a semisolid) was prepared
according to the general procedure (Method A) from donor 24

P. Peng et al. / Carbohydrate Research 384 (2014) 1–8
7
(20.0 mg, 34
l
mol) and acceptor 13 (15.0 mg, 25
l
mol), and was
4.2.13. Methyl 6-O-(6-O-(2,3,4,6-tetra-O-benzoyl-b-
galactopyranosyl)-2,3,4-tri-O-benzoyl-b- -glucopyranosyl)-
2,3,4-tri-O-benzoyl- -glucopyranoside (31)
Compound 31 was synthesized by a preactivation-based itera-
tive one-pot procedure. After the donor 4 (26.4 mg, 38 mol), Ph2-
SO (8.5 mg, 42 mol) and activated 4 Å powdered molecular sieves
D-
purified by column chromatography (petroleum ether/ethyl ace-
D
tate = 2:1). ½a 2D5
ꢁ
ꢀ9.0° (c 3.11 in CHCl3); 1H NMR (400 MHz, CDCl3):
a-D
d 7.96 (d, 2H, J = 7.6 Hz), 7.89 (d, 2H, J = 7.6 Hz), 7.78 (d, 2H,
J = 7.6 Hz), 7.64 (d, 1H, J = 7.2 Hz), 7.52 (t, 2H, J = 7.2 Hz), 7.35–7.43
(m, 5H), 7.24–7.27 (m, 10H), 5.88 (t, 1H, J = 9.6 Hz, H-3), 5.43–5.52
(m, 2H, H-2, H-4), 5.35 (d, 1H, J = 2.8 Hz, H-40), 5.12 (d, 1H.
J = 10.0 Hz, H-1), 4.91 (d, 1H, J = 10.4 Hz, H-30), 4.69–4.75 (m, 3H),
4.47 (d, 1H, J = 8.4 Hz, H-10), 4.11 (d, 2H, J = 6.4 Hz), 3.88–4.04 (m,
3H), 3.76–3.82 (m, 2H), 2.36 (s, 3H), 2.14 (s, 3H), 2.04 (s, 3H), 2.00
(s, 3H). 13C NMR (100 MHz, CDCl3): d 170.35, 170.20, 170.18,
165.69, 165.49, 164.96, 154.39, 140.95, 133.71, 133.34, 133.24,
131.58, 130.84, 129.83, 129.81, 129.68, 129.04, 128.74, 128.68,
128.50, 128.43, 128.38, 128.26, 127.06, 101.68, 95.68, 86.49, 78.83,
74.48, 74.01, 70.67, 70.63, 70.35, 69.04, 67.79, 66.43, 61.35, 52.41,
21.05, 20.64, 20.57. HRMS (ESI) Calcd for C49Cl3H49NO17S [M+H]+:
1060.1781. Found: 1060.1761. HRMS(ESI) Calcdfor C49Cl3H52N2O17-
S [M+NH4]+: 1077.2047. Found: 1077.2025.
l
l
were stirred at room temperature in dichloromethane (2 mL) for
30 min under an argon atmosphere, the solution was cooled to
ꢀ72 °C and Tf2O (7.0
lL, 42 lmol) was added. The temperature
was raised to ꢀ20 °C slowly. Stirring at this temperature for
5 min, the reaction mixture was cooled back to ꢀ72 °C and build-
ing block 13 (15.0 mg, 25 lmol) was added. The reaction was
warmed to room temperature and further stirred for 15 min before
cooling back to ꢀ72 °C. Subsequently, Ph2SO (5.1 mg, 25 mol) and
Tf2O (4.1 L, 25 mol) was added to the mixture. After the mixture
was stirred vigorously for 10 min, the acceptor 30 (13.9 mg,
30 mol) was added. The reaction was warmed gradually to room
l
l
l
l
temperature and quenched by triethylamine (0.2 mL). The precip-
itated was filtered off through a pad of Celite. The filtrate was con-
centrated and the residue was purified by column chromatography
on silica gel (petroleum ether/ethyl acetate = 1:1), affording com-
4.2.11. o-Tolyl 3-O-(2,3,4,6-tetra-O-benzyl-
osyl)-2,4,6-tri-O-benzoyl-1-thio-b- -galactopyranoside (27)
Compound 27 (27.0 mg, 85% yield as a semisolid) was prepared
according to the general procedure (Method B) from donor 26
(20.0 mg, 31 lmol) and acceptor 21 (16.7 mg, 28 lmol), and was
a-D-galactopyran
D
pound 31 as semisolid (29.0 mg, 76% yield). ½a D25
ꢁ
+40.7° (c 2.95 in
CHCl3); 1H NMR (400 MHz, CDCl3): d 8.08 (d, 2H, J = 8.4 Hz),
8.01–8.03 (m, 4H), 7.92–7.96 (m, 6H), 7.84 (d, 2H, J = 8.4 Hz),
7.74–7.81 (m, 6H), 7.21–7.62 (m, 33H), 6.09 (t, 1H, J = 9.6 Hz, H-
3), 6.00 (d, 1H, J = 3.2 Hz, H-400), 5.86 (dd, 1H, J = 3.6, 10.4 Hz, H-
300), 5.77 (dd, 1H, J = 8.0, 9.6 Hz, H-20), 5.74 (t, 1H, J = 9.6 Hz, H-
30), 5.47 (t, 1H, J = 10.0 Hz, H-4), 5.33 (dd, 1H, J = 7.6, 9.6 Hz, H-
200), 5.21 (t, 1H, J = 9.6 Hz, H-40), 5.16 (dd, 1H, J = 3.6, 10.4 Hz, H-
2), 5.10 (d, 1H, J = 8.0 Hz, H-10) 5.08 (d, 1H, J = 3.6 Hz, H-1), 4.69
(d, 1H, J = 8.0 Hz, H-100), 4.57 (dd, 1H, J = 9.2, 13.6 Hz, H-6a00),
4.32–4.37 (m, 2H, H-500, H-6b00), 4.00–4.06 (m, 3H, H-5, H-6a, H-
6a0), 3.89–3.95 (m, 2H, H-50, H-6b0), 3.56 (dd, 1H, J = 6.4, 11.6 Hz,
H-6b), 3.12 (s, 3H, OMe). 13C NMR (100 MHz, CDCl3): d 165.94,
165.74, 165.70, 165.65, 165.57, 165.51, 165.41, 165.38, 165.31,
164.96, 133.49, 133.44, 133.37, 133.27, 133.24, 133.20, 133.13,
133.05, 132.96, 130.01, 129.95, 129.88, 129.80, 129.69, 129.66,
129.51, 129.44, 129.32, 129.15, 129.01, 128.93, 128.87, 128.72,
128.59, 128.49, 128.45, 128.40, 128.35, 128.23, 128.19, 101.49,
101.06, 96.64, 74.80, 72.73, 72.10, 71.87, 71.45(2ꢂ), 70.27(2ꢂ),
70.08, 69.54, 68.69, 68.48, 68.47, 67.82, 62.08, 55.15. HRMS (ESI)
Calcd for C89H78NO26 [M+NH4]+: 1576.4818. Found: 1576.4807.
purified by column chromatography (petroleum ether/ethyl ace-
tate = 5:1). ½a 2D5
ꢁ
+43.6° (c 1.10 in CHCl3); 1H NMR (400 MHz,
CDCl3): d 8.02–8.05 (m, 6H), 7.38–7.62 (m, 9H), 7.10–7.30 (m,
27H), 6.95 (t, 1H, J = 6.8 Hz), 5.90 (d, 1H, J = 2.8 Hz, H-4), 5.76 (t,
1H, J = 10.0 Hz, H-2), 5.23 (d, 1H, J = 3.2 Hz, H-10), 4.78 (d, 1H,
J = 10.0 Hz, H-1), 4.70 (d, 1H, J = 11.6 Hz, PhCH2), 4.39–4.49 (m,
6H), 4.19–4.30 (m, 4H), 3.98 (t, 1H, J = 6.4 Hz, H-5), 3.83–3.89 (m,
2H, H-20, H-50), 3.47 (dd, 1H, J = 2.8, 10.4 Hz, H-30), 3.33 (dd, 1H,
J = 6.8, 9.6 Hz, H-6a0), 3.22 (d, 1H, J = 1.6 Hz, H-40), 3.17 (dd, 1H,
J = 5.6, 9.6 Hz, H-6b0), 2.26 (s, 3H, Me). 13C NMR (100 MHz, CDCl3):
d 166.05, 165.89, 164.83, 140.30, 138.79, 138.49, 138.34, 133.28,
133.18, 132.98, 132.68, 130.22, 130.18, 129.82, 129.67, 129.57,
129.19, 128.46, 128.41, 128.40, 128.30, 128.15, 128.11, 128.08,
127.96, 127.63, 127.55, 127.45, 127.29, 127.20, 127.04, 126.47,
94.33, 87.06, 78.76, 75.46, 75.23, 74.96, 74.43, 74.05, 73.26,
73.22, 72.34, 70.10, 69.30, 66.52, 63.15, 20.93. HRMS (ESI) Calcd
for C68H68NO13S [M+NH4]+: 1138.4006. Found: 1138.4442. Calcd
for C68H64O13SK [M+K]+: 1159.3694. Found: 1159.3652.
4.2.12. o-Tolyl 6-O-(2,3-di-O-benzoyl-4,6-O-benzylidene-b-
D
-
Acknowledgments
galactopyranosyl)-2,3,4-tri-O-benzoyl-1-thio-b-D-
glucopyranoside (29)
Compound 29 (24.0 mg, 77% yield as a semisolid) was prepared
according to the general procedure (Method B) from donor 28
This work was financially supported by the Grants
(2012AA021504, 2012ZX09502001-001, 2012CB822100) from the
Ministry of Science and Technology of China, the National Natural
Science Foundation of China (Grant No. 21232002), and Beijing
Higher Education Young Elite Teacher Project.
(20.0 mg, 34 lmol) and acceptor 13 (16.0 mg, 29 lmol), and was
purified by column chromatography (petroleum ether/ethyl ace-
tate = 2:1). ½a 2D5
ꢁ
+40.0° (c 1.00 in CHCl3); 1H NMR (400 MHz,
CDCl3): d 7.99 (d, 2H, J = 7.6 Hz), 7.92 (d, 2H, J = 7.2 Hz), 7.86 (d,
4H, J = 7.6 Hz), 7.75 (d, 2H, J = 7.2 Hz), 7.09- 7.50 (m, 29H), 5.85
(dd, 1H, J = 8.4, 10.4 Hz, H-20), 5.78 (t, 1H, J = 9.6 Hz, H-3), 5.51 (s,
1H, PhCH), 5.44 (t, 1H, J = 9.6 Hz, H-2), 5.36 (t, 1H, J = 9.6 Hz, H-
4), 5.28 (dd, 1H, J = 3.6, 10.4 Hz, H-30), 4.90 (d, 1H, J = 8.0 Hz, H-
10), 4.89 (d, 1H, J = 10.0 Hz, H-1), 4.57 (d, 1H, J = 3.2 Hz, H-40),
4.27 (d, 1H, J = 12.4 Hz, H-6a0), 3.96–4.08 (m, 4H, H-6b0, H-5, H-
6a, H-6b), 3.60 (s, 1H, H-50), 2.20 (s, 3H, Me). 13C NMR (100 MHz,
CDCl3): d 166.17, 165.64, 165.42, 165.29, 165.01, 139.87, 137.45,
133.44, 133.31, 133.22, 133.11, 132.91, 132.13, 130.19, 129.95,
129.81, 129.73, 129.69, 129.64, 129.20, 129.17, 128.85, 128.72,
128.38, 128.32, 128.20, 128.07, 127.06, 126.20, 101.00, 100.74,
86.66, 78.56, 74.18, 73.50, 72.94, 70.63, 69.43, 68.97, 68.83,
67.73, 66.57, 20.87. HRMS (ESI) Calcd for C61H56NO15S [M+NH4]+:
1074.3365. Found: 1074.3377.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.carres.2013.11.009.
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