Synthesis of a trisaccharide repeating unit of the O-antigen from Burkholderia cenocepacia and its dimer

Article abstract of DOI:10.1016/j.carres.2017.09.001

The trisaccharide repeating unit of an O-antigen derived from Burkholderia cenocepacia and its dimer, i.e., α-L-Rhap-(1 → 3)-α-D-GalpNAc-(1 → 3)-β-D-GalpNAc-O(CH₂)₃N₃ (1) and α-L-Rhap-(1 → 3)-α-D-GalpNAc-(1 → 3)-β-D-GalpNAc-(1 → 4)-α-L-Rhap-(1 → 3)-α-D-GalpNAc-(1 → 3)-β-D-GalpNAc-O(CH₂)₃N₃ (2), respectively, were synthesized via a highly convergent strategy. Glycosylation of galactosaminyl acceptor 4 with galactosaminyl trichloroacetimidate donor 5 was followed by condensation of resulting disaccharide acceptor 12 with rhamnosyl imidate donor 6 to furnish stereoselectively trisaccharyl thioglycoside 3, which was used as a key and common glycosyl donor for the construction of both 1 and 2. Title molecule 1 was prepared by glycosylation of 3-azidopropanol with 3 and subsequently global deprotection, whereas coupling reaction of 3 with a trisaccharide acceptor 21 containing an 2,3-O-position acetonide-modified rhamnose residue, followed by global deprotection, generated the dimer 2 in a convergent [3 + 3] manner.

Full text of DOI:10.1016/j.carres.2017.09.001

Carbohydrate Research 451 (2017) 1e11
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Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Synthesis of a trisaccharide repeating unit of the O-antigen from
Burkholderia cenocepacia and its dimer
,
c
,
, *
Ningning Bi a, Chenghe Xiong a, Guoxia Jin b, Zhongwu Guo a **, Guofeng Gu a
a National Glycoengineering Research Center, Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, 27
Shanda Nan Lu, Jinan 250010, PR China
b College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging, Key
Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Normal University, 88 Wenhua Dong Lu, Jinan 250014, PR China
c Department of Chemistry, University of Florida, 214 Leigh Hall, Gainesville, FL 32611, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
The trisaccharide repeating unit of an O-antigen derived from Burkholderia cenocepacia and its dimer, i.e.,
Received 14 August 2017
Received in revised form
5 September 2017
Accepted 5 September 2017
Available online 8 September 2017
a
-L-Rhap-(1 / 3)-
a
-D-GalpNAc-(1 / 3)-
b
-D-GalpNAc-O(CH2)3N3 (1) and
a
-L-Rhap-(1 / 3)-
a-D-Galp-
NAc-(1 / 3)- -D-GalpNAc-(1 / 4)-
b
a-L-Rhap-(1 / 3)-
a
-D-GalpNAc-(1 / 3)-b
-D-GalpNAc-O(CH2)3N3
(2), respectively, were synthesized via a highly convergent strategy. Glycosylation of galactosaminyl
acceptor 4 with galactosaminyl trichloroacetimidate donor 5 was followed by condensation of resulting
disaccharide acceptor 12 with rhamnosyl imidate donor 6 to furnish stereoselectively trisaccharyl thi-
oglycoside 3, which was used as a key and common glycosyl donor for the construction of both 1 and 2.
Title molecule 1 was prepared by glycosylation of 3-azidopropanol with 3 and subsequently global
deprotection, whereas coupling reaction of 3 with a trisaccharide acceptor 21 containing an 2,3-O-po-
sition acetonide-modified rhamnose residue, followed by global deprotection, generated the dimer 2 in a
convergent [3 þ 3] manner.
Keywords:
Burkholderia cenocepacia
Lipopolysaccharide
O-antigen
Repeating unit
Synthesis
© 2017 Elsevier Ltd. All rights reserved.
1. Introduction
clinically uncontrollable “cepacia syndrome”, such as necrotizing
pneumonia and septicemia [15]. However, the pathogenic mecha-
Polysaccharides on the bacterial cell surface, such as lipopoly-
saccharides (LPSs) [1], capsular polysaccharides (CPSs) [2], extra-
cellular polysaccharides (EPSs) [3] and so on, play an important role
in various biological events [4,5]. For example, many of the poly-
saccharides are important virulence factors for bacterial pathoge-
nicity [1,6,7] and are crucial immunomodulators useful for the
development of new carbohydrate-based diagnostic agents and
vaccines [8e12].
The Burkholderia cepacia complex (Bcc) represents a group of
phenotypically similar but genotypically diverse Gram-negative
bacteria [13,14] that are opportunistic human pathogens [15e17].
Bcc bacteria can occasionally cause serious lung infections in pa-
tients with cystic fibrosis (CF), resulting in a high mortality due to
nism of Bcc infection still remains unclear, and therefore, detailed
studies of Bcc, and the development of effective strategies to con-
trol Bcc infection are in urgent demand.
B. cenocepacia is one of the two predominant Bcc species found
in CF patients, accounting for approximate 46% of Bcc infections in
the United States [18]. B. cenocepacia infection is frequently con-
nected with poor clinical recovery and high rate of mortality [19]. It
has been reported that the LPS O-polysaccharides, also known as O-
antigens, of B. cenocepacia K56-2 were associated with bacterial
invasion and virulence [20,21]. It not only induced inflammatory
cytokine IL-1b production [20] but also modulated phagocytosis
and interfered with bacterial adhesion to bronchial epithelial cells
[21]. Therefore, the O-antigen of B. cenocepacia might be a useful
target in studying pathogenic mechanism of Bcc and developing
carbohydrate-based therapeutic agents against Bcc diseases.
An O-antigen from B. cenocepacia K56-2, which is composed of a
* Corresponding author.
trisaccharide repeating unit /4)-a-L-Rhap-(1 / 3)-a-D-GalpNAc-
** Corresponding author. National Glycoengineering Research Center, Shandong
Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong
University, 27 Shanda Nan Lu, Jinan 250010, PR China.
(1 / 3)- -D-GalpNAc-(1/ (Fig. 1), was recently characterized [22].
b
As a part of our ongoing research effort to develop vaccines against
Bcc [23e25], we described herein the first chemical synthesis of the
E-mail addresses: zguo@chem.ufl.edu (Z. Guo), guofenggu@sdu.edu.cn (G. Gu).
http://dx.doi.org/10.1016/j.carres.2017.09.001
0008-6215/© 2017 Elsevier Ltd. All rights reserved.

2
N. Bi et al. / Carbohydrate Research 451 (2017) 1e11
Fig. 1. Structures of the O-antigen from B. cenocepacia and the synthetic targets 1 and 2.
repeating unit of this O-antigen 1 and its dimer 2 (Fig. 1). These
synthetic targets were designed to carry an azido group at their
reducing end, which would enable their regioselective modifica-
tion, such as conjugation with carrier molecules to generate gly-
coconjugates that are useful for various biological and
immunological studies.
conventional condition with trimethylsilyl triflate (TMSOTf) as a
promoter yielded 9 (62%) as the major product, which was a thio
transfer product [33,34] probably because of the relatively low
reactivity of the 3-OH group in 4. To solve the problem, inverse
glycosylation strategy [35] was employed, in which 4 was pre-
mixed with the promotor at ꢀ15 ꢁC for 1 h, followed by the addi-
tion of 5 (1.2 equiv) at 0 ꢁC. In this way,
a
-linked disaccharide 10
was furnished as the main product (a/b 2:1) in a 63% yield. When
employing a mixture of toluene and 1,4-dioxane (v/v 1:1) as the
2. Results and discussion
solvent [36], the reaction gave 10 as the only anomer in a good yield
As shown in Scheme 1, retrosynthetic analysis of the synthetic
targets 1 and 2 resulted in a key trisaccharyl donor 3, which could
act as a common building block for the introduction of a 3-
azidopropyl group at the reducing end and for oligomerization as
well. In turn, 3 could be assembled from three monosaccharides,
(65%). The stereoselectivity of the newly formed a-glycosidic bond
was verified by the small coupling constant (J1 ,2ꢀ¼ 3.6 Hz) of its H-10
0
signal at d
4.98 ppm in the 1H NMR spectrum of 10. At this stage, the
20-azido group in 10 was converted into acetamido group using
thioacetyl acid (AcSH) in pyridine [37], affording 11 in a high yield
(85%). Basic selective deacetylation of 11 in methanol afforded 12,
which served as a glycosyl acceptor glycosylated with 6 under the
promotion of TMSOTf to furnish fully protected trisaccharide 3 in a
namely, galactosaminyl acceptor
chloroacetimidate donor
4
[26], galactosaminyl tri-
5
[27] and rhamnosyl tri-
chloroacetimidate donor 6. We planned to use phathalyl and
benzoyl groups to protect the 2-N and 2-O-positions in 4 and 6 to
boost 1,2-trans glycosylation reactions based on neighboring group
participation. Alternatively, an azido group at the C-2 position in 5
was chosen to prevent neighboring group participation and
thereby facilitate stereoselective formation of 1,2-cis glycosidic
bond [28,29].
The synthesis commenced with the preparation of 4 [26] and 5
[27] according to reported procedures. Thereafter, 6 was prepared
from reported rhamnoside 7 [30] in four steps (Scheme 2). Removal
of the isopropylidene group in 7 with 80% aqueous acetic acid
followed by benzoylation of the resultant 2,3-diol with benzoyl
chloride in pyridine provided 8 in a 66% overall yield. Next, 8 was
converted into hemiacetal by reaction with N-iodosuccinamide
(NIS) and silver triflate (AgOTf) in wet CH2Cl2 [25], which was fol-
lowed by trichloroacetimidation [31] under basic conditions using
trichloroacetonitrile and 1,8-diazabicydo[5.4.0]undec-7-ene (DBU)
[32] to give glycosyl donor 6 in a 67% yield (two steps).
65% overall yield. The a-rhamnosidic bond in 3 was characterized
by its 1JC-1,H-1 coupling constant (171.6 Hz) for its 1H-coupled gHSQC
spectrum [38].
Starting from 3, the synthetic target 1 was readily assembled
according to Scheme 4. The reaction between 3 and 3-azido-1-
propanol proceeded smoothly in the presence of NIS and TMSOTf
to produce 13 in a 76% yield. It was then subjected to global
deprotection in four steps. First, 13 was treated with hydrazine
hydrate in refluxing ethanol [39] to remove the acyl and Phth
groups. Then, the exposed amino and hydroxyl groups were acet-
ylated with acetic anhydride in pyridine. This was followed by the
cleavage of benzylidene groups using 80% aqueous acetic acid.
Finally, any remaining O-acetyl groups in the product were selec-
tively removed with sodium methoxide in methanol to afford 1 in a
75% overall yield (four steps) after purification by size-exclusion
chromatography on a Sephadex G-10 column. Compound 1 was
fully characterized by various NMR and MS data.
The key trisaccharyl thioglycoside 3 was assembled by a step-
wise glycosylation strategy as outlined in Scheme 3. Interestingly,
On the other hand, 13 was selectively dechloroacetylated with
thiourea [40] to generate 14 (80% yield) as a glycosyl acceptor
glycosylation of
4 with trichloroacetimidate 5 under the
Scheme 1. Retrosynthetic analysis of synthetic targets 1 and 2.

N. Bi et al. / Carbohydrate Research 451 (2017) 1e11
3
Scheme 2. Synthesis of rhamnosyl donor 6.
Scheme 3. Synthesis of trisaccharide 3 as a glycosyl donor.
Scheme 4. Synthesis of target molecule 1.
(Scheme 5). The upfield shift of the rhamnosyl H-4 signal at
3.72 ppm in the 1H NMR spectrum of 14 confirmed the correct
electron-withdrawing benzoyl groups on C-2Rha and C-3Rha posi-
tions. To verify the hypothesis, a rhamnosyl acceptor 15 containing
a 2,3-O-acetonide group was prepared and glycosylated with 3
(Scheme 5). Under the same conditions, the reaction proceeded
smoothly to furnish 16 in an 82% yield. The newly formed
d
regiochemistry. Next, a convergent [3 þ 3] gylocsylation strategy
was attempted to construct 2 through the coupling of 3 and 14.
Unfortunately, this reaction was very sluggish and gave only a trace
amount of the hexasaccharide detectable by MS. Varied reaction
conditions, including different solvents, catalysts and temperatures
or utilizing more reactive trichloroacetimidate and phosphate as
glycosyl donors were attempted but failed to accomplish the
desired result. We assumed that this might be because of the low
reactivity of the 4Rha-OH group in 14 due to the presence of
b
eglycosidic bond was confirmed by the large coupling constant
(9.0 Hz) of the galctosaminyl H-1 signal at
d
5.37 ppm in the 1H
NMR spectrum of 16.
Encouraged by these results, we redesigned and synthesized
another trisaccharide 21 as a glycosyl acceptor, as outline in Scheme
6, to achieve the [3 þ 3] assembly of hexasaccharide 2. In 21, the

4
N. Bi et al. / Carbohydrate Research 451 (2017) 1e11
Scheme 5. Glycosylations between 3 with different glycosyl acceptors.
Scheme 6. Synthesis of trisaccharide acceptor 21.
rhamnose 2- and 3-O-positions were protected with an acetonide
group. Therefore, 11 was coupled with 3-azido-1-propanol under
the promotion of NIS and TMSOTf to furnish 17, which was selec-
tively de-O-acetylated with sodium methoxide in methanol to
afford 18 (in an overall yield of 61%) as a glycosyl acceptor. Again,
promoted with NIS-AgOTf to smoothly produce the fully protected
hexasaccharide 22 in a 76% yield. The newly formed -glycosidic
bond was again verified by the large coupling constant (J ¼ 8.4 Hz)
of galactosaminyl H-100 signal at 5.35 ppm in the 1H NMR spec-
trum of 22. Global deprotection of 22 in four steps by the same
sequence as described for 1 produced 2 in a 64% overall yield.
Synthetic target and all of the synthetic intermediates were fully
characterized by various NMR and MS data.
b
d
the upfield shift of the H-30 signal at
d
3.51 ppm in the 1H NMR
spectrum of 18 confirmed the correct regiochemistry. Glycosylation
of 18 with 19 [41] was also carried out with NIS and AgOTf as
promoters to afford predominantly the
(78%). The 1H-coupled gHSQC spectrum of 20 showed that the C-
1Rha/H-1Rha coupling constant was 169.2 Hz, confirming the
a-linked 20 in a high yield
3. Conclusions
a
configuration of the new glycosidic bond in 20. Finally, selective
removal of the 2-O-acetyl group in 20 with sodium methoxide in
methanol gave 21 in an 85% yield.
Eventually, the synthetic target 2 was assembled by a procedure
shown in Scheme 7. The coupling reaction between 21 and 3 was
In conclusion, we have described here an efficient synthesis of
the trisaccharide repeating unit of B. cenocepacia O-antigen and its
dimer. In this synthesis, trisaccharyl thioglycoside 3 was used as a
common glycosyl donor not only for the glycosylation of 3-azido-1-
propanol to achieve 1 but also for elongating the carbohydrate

N. Bi et al. / Carbohydrate Research 451 (2017) 1e11
5
Scheme 7. Synthesis of target hexasaccharide 2.
chain of 21 to achieve hexasaccharide 2 via a highly convergent
performed at < 60 ꢁC under diminished pressure.
[3 þ 3] strategy. Trisaccharide 1 was smoothly prepared from
stepwise glycosylation reactions of monosaccharide building
blocks. In this process, the a-glycosidic linked was accomplished
using donor 5 with the galactosamine 2-amino group protected as a
non-participating azido group. For the synthesis of 2, trisaccharide
14, in which the rhamnose 2- and 3-O-positons were protected
with benzoyl groups, was proved to be a torpid glycosyl acceptor. To
4.2. para-Tolyl 2,3-di-O-benzoyl-4-O-chloroacetyl-1-thio-a-L-
rhamnopyranoside (8)
A solution of 7 (3.02 g, 7.82 mmol) in 80% HOAc (10 mL) was
stirred at 70 ꢁC for 3 h, and then co-evaporated with toluene
(2 ꢂ 15 mL) under reduced pressure. The resulting residue was
purified by silica gel column chromatography (hexaneeethyl ace-
solve the problem, trisaccharide 21 containing
a 2,3-O-iso-
propylidene group on the rhamnose residue was designed and then
successfully glycosylated with 3 to afford the desired molecule. In
addition, both synthetic targets 1 and 2 carried a 3-azidopropyl
linker at their reducing end, allowing for their convenient attach-
ment to functionalized biomolecules for the exploration of various
biological problems, such as B. cenocepacia immunology and
development of O-antigen-based vaccines against Bcc infections.
tate 2:1 to 1:2) to give para-tolyl 4-O-chloroacetyl-1-thio-
rhamnopyranoside (2.11 g, 78%) as a white foamy solids. 1H NMR
(600 MHz, CD3OD):
a-L-
d
7.34 (d, J ¼ 8.4 Hz, 2 H, ArH), 7.13 (d, J ¼ 7.8 Hz,
2 H, ArH), 5.32 (s, 1 H, H-1), 5.04 (t, J ¼ 9.6 Hz, 1 H, H-4), 4.29, 4.24
(2 d, J ¼ 15.0 Hz, 2 H, -OCOCH2Cl), 4.25e4.20 (m, 1 H, H-5), 4.11 (dd,
J ¼ 3.0, 1.8 Hz, 1 H, H-2), 3.82 (dd, J ¼ 9.6, 3.0 Hz, 1 H, H-3), 2.30 (s,
3 H, -SPhCH3), 1.15 (d, J ¼ 6.0 Hz, 3 H, H-6); 13C NMR (150 MHz,
CD3OD): d 167.4, 137.6, 131.9, 130.2, 129.3, 88.9, 76.0, 72.3, 69.3, 67.0,
4. Experimental section
40.4, 19.7, 16.2; ESI-TOF HRMS m/z: Calcd for C15H19ClO5SNa
[M þ Naþ] 369.0539; found, 369.0525. To a solution of the above
product (1.99 g, 5.75 mmol) in pyridine (10 mL) was added BzCl
(2 mL, 17.25 mmol) at 0 ꢁC. The mixture was stirred at rt for 2 h and
then diluted with CH2Cl2 (60 mL). The organic phase washed with
1 M HCl (2 ꢂ 30 mL) and brine (30 mL), dried over anhydrous
Na2SO4, and concentrated. The residue was purified by silica gel
column chromatography (hexaneeethyl acetate 8:1) to give 8
4.1. General methods
Optical rotations were determined at 25 ꢁC with a Rudolph
Autopol I automatic polarimeter. 1H and 13C NMR spectra were
recorded with an Agilent 600 MHz spectrometer for solutions in
CDCl3, CD3CN, CD3OD, or D2O. Chemical shifts (d) are given in ppm
downfield from internal Me4Si or with the DHO signal as reference
when D2O was used as the solvent. Positive-mode electrospray
ionization (ESI) high-resolution mass spectroscopy (HRMS) was
recorded on an IT-TOF spectrometer. Thin layer chromatography
(TLC) was performed on silica gel HF254 plates, detected by charring
using 30% (v/v) H2SO4 in MeOH or by means of a UV detector. Silica
gel column chromatography was conducted with mixtures of ethyl
acetate and hexane as the eluents. Solution concentration was
(2.7 g, 85%) as a white foamy solid. [
(600 MHz, CDCl3):
a
]
25 þ15 (c 0.2, CHCl3); 1H NMR
D
d
8.03 (d, J ¼ 7.8 Hz, 2 H, ArH), 7.88 (d, J ¼ 8.4 Hz,
2 H, ArH), 7.56 (t, J ¼ 7.8 Hz, 1 H, ArH), 7.51 (t, J ¼ 7.8 Hz, 1 H, ArH),
7.46 (t, J ¼ 7.8 Hz, 2 H, ArH), 7.41 (d, J ¼ 8.4 Hz, 2 H, ArH), 7.35 (t,
J ¼ 7.8 Hz, 2 H, ArH), 7.14 (d, J ¼ 7.8 Hz, 2 H, ArH), 5.86 (dd, J ¼ 3.6,
1.2 Hz, 1 H, H-2), 5.65 (dd, J ¼ 10.2, 3.6 Hz, 1 H, H-3), 5.56 (d,
J ¼ 1.2 Hz,1 H, H-1), 5.51 (t, J ¼ 10.2 Hz, 1 H, H-4), 4.62e4.55 (m, 1 H,
H-5), 4.02, 3.96 (2 d, J ¼ 14.4 Hz, 2 H, -OCOCH2Cl), 2.33 (s, 3 H,

6
N. Bi et al. / Carbohydrate Research 451 (2017) 1e11
-SPhCH3), 1.35 (d, J ¼ 6.6 Hz, 3 H, H-6); 13C NMR (150 MHz, CDCl3):
diluted with CH2Cl2 (20 mL), filtered through a pad of Celite, and
the filtrate was concentrated. The residue was purified by silica gel
d
166.7, 165.3 (2C), 138.3, 133.5, 133.4, 132.6, 130.2, 130.0, 129.8,
129.7, 129.2, 128.8, 128.6, 128.5, 86.1, 73.3, 72.2, 70.1, 67.4, 40.5, 21.1,
17.4; ESI-TOF HRMS m/z: Calcd for C29H27ClO7SNa [M þ Na]þ
577.1064; found, 577.1033.
column chromatography (hexaneeethyl acetate 10:1 to 2:1) to
25
yield 10 (360 mg, 65%) as a white foamy solid. [
a
]
þ96 (c 0.3,
D
CHCl3); 1H NMR (600 MHz, CDCl3):
d
7.89 (d, J ¼ 6.6 Hz, 1 H, ArH),
7.83 (d, J ¼ 7.2 Hz, 1 H, ArH), 7.79e7.72 (m, 2 H, ArH), 7.52 (d,
J ¼ 6.6 Hz, 2 H, ArH), 7.44e7.37 (m, 5 H, ArH), 7.36e7.31 (m, 2 H,
ArH), 7.30e7.28 (m, 3 H, ArH), 7.00 (d, J ¼ 7.8 Hz, 2 H, ArH), 5.62 (s,
1 H, CHPh), 5.52 (d, J ¼ 9.6 Hz, 1 H, H-1GalN), 5.28 (s, 1 H, CHPh), 5.07
4.3. 2,3-Di-O-benzoyl-4-O-chloroacetyl-a-L-rhamnopyranosyl
trichloroacetimidate (6)
0
0
After 8 (2.5 g, 4.51 mmol) was dissolved in CH2Cl2 and CH3CN (v/
v 1:1, 40 mL) containing two drops of H2O (100 L), NIS (1.21 g,
(dd, J ¼ 10.8, 3.6 Hz, 1 H, H-3GalN ), 4.98 (d, J ¼ 3.6 Hz, 1 H, H-1GalN ),
4.74 (t, J ¼ 10.2 Hz, 1 H, H-2GalN), 4.70 (dd, J ¼ 10.2, 3.0 Hz, 1 H, H-
m
5.41 mmol) and AgOTf (0.1 g, 0.39 mmol) were added at 0 ꢁC. The
reaction mixture was stirred at same temperature for 4 h, and then
neutralized with Et3N and concentrated, and the residue was
briefly purified by flash column chromatography (hexaneeethyl
acetate 4:1 to 1:1). The resultant hemiacetal was then dissolved in
CH2Cl2 (10 mL) at 0 ꢁC, and trichloroacetonitrile (1.8 mL,12.5 mmol)
3GalN), 4.45 (d, J ¼ 3.0 Hz, 1 H, H-4GalN), 4.43 (d, J ¼ 12.0 Hz, 1 H, H-
0
6aGalN), 4.22 (d, J ¼ 3.0 Hz, 1 H, H-4GalN ), 4.10 (d, J ¼ 12.0 Hz, 1 H, H-
0
6bGalN), 3.85 (dd, J ¼ 10.8, 3.6 Hz,1 H, H-2GalN ), 3.67 (s,1 H, H-5GalN),
0
0
3.55 (d, J ¼ 12.6 Hz, 1 H, H-6aGalN ), 3.42 (s, 1 H, H-5GalN ), 3.19 (d,
0
J ¼ 12.6 Hz, 1 H, H-6bGalN ), 2.30 (s, 3 H, -SPhCH3), 2.07 (s, 3 H,
-OCOCH3); 13C NMR (150 MHz, CDCl3):
d
170.0 (C¼O), 168.8 (C¼O),
and DBU (100
ꢁC for 1 h, and then concentrated. The residue was subjected to
flash column chromatography (hexaneeethyl acetate 4:1) to give 6
mL) was added. The reaction mixture was stirred at
167.2 (C¼O), 138.1, 137.8, 137.2, 134.5, 134.4, 133.6, 131.7, 131.5, 129.5,
0
129.0, 128.8, 128.1, 128.0, 127.4, 126.5, 125.9, 123.53, 123.49, 100.9
0
(CHPh), 100.40 (CHPh), 100.3 (C-1GalN ), 82.9 (C-1GalN), 77.8 (C-
0
25
(1.78 g, 67% for 2 steps) as a white foamy solid. [
a
]
þ54 (c 0.3,
3GalN), 73.8 (C-4GalN), 72.9 (C-4GalN ), 70.2 (C-5GalN), 69.3 0(C-6GalN),
D
0
0
0
CHCl3); 1H NMR (600 MHz, CDCl3):
d
8.80 (s, 1 H, -NH), 8.06 (d,
69.2 (C-3GalN ), 68.5 (C-6GalN ), 63.3 (C-5GalN ), 57.4 (C-2GalN ), 51.2 (C-
2GalN), 21.2 (-SPhCH3), 20.9 (-OCOCH3); ESI-TOF HRMS m/z: Calcd
for C43H44N5O11S [M þ NH4]þ 838.2753; Found 838.2717.
J ¼ 8.4 Hz, 2 H, ArH), 7.87 (d, J ¼ 7.2 Hz, 2 H, ArH), 7.62 (t, J ¼ 7.8 Hz,
1 H, ArH), 7.54e7.45 (m, 3 H, ArH), 7.35 (t, J ¼ 7.8 Hz, 2 H, ArH), 6.43
(d, J ¼ 1.8 Hz, 1 H, H-1), 5.83 (dd, J ¼ 3.6, 1.8 Hz, 1 H, H-2), 5.73 (dd,
J ¼ 10.2, 3.6 Hz, 1 H, H-3), 5.54 (t, J ¼ 10.2 Hz, 1 H, H-4), 4.33e4.26
(m, 1 H, H-5), 4.00, 3.95 (2 d, J ¼ 14.4 Hz, 2 H, -OCOCH2Cl), 1.39 (d,
4.6. para-Tolyl 2-acetamido-3-O-acetyl-4,6-O-benzylidene-2-
deoxy-a-D-galactopyranosyl-(1 / 3)-4,6-O-benzylidene-2-deoxy-
J ¼ 6.0 Hz, 3 H, H-6); 13C NMR (150 MHz, CDCl3):
d
166.6, 165.4,
2-phthalimido-1-thio-b
-D-galactopyranoside (11)
165.2,159.9,133.7, 133.5,129.9,129.7,128.8,128.7,128.6,128.5, 94.5,
90.6, 72.4, 69.5, 68.97, 68.96, 40.4, 17.6.
To a solution of 10 (230 mg, 0.28 mmol) in pyridine (2 mL) was
added AcSH (4 mL, 202 mmol) at 0 ꢁC. The mixture was allowed to
warm up to rt and stirred for 6 h, and then diluted with ethyl ac-
etate (50 mL) and washed with saturated aq. NaHCO3 (2 ꢂ 25 mL)
and brine (25 mL). The organic phase was dried over anhydrous
Na2SO4 and concentrated. The residue was purified by silica gel
column chromatography (hexaneeethyl acetate 5:1 to 1:2) to give
4.4. para-Tolyl 3-O-acetyl-2-azido-4,6-O-benzylidene-2-deoxy-b-
D-galactopyranoside (9)
To a stirred mixture of 4 (150 mg, 0.30 mmol), 5 (172 mg,
0.36 mmol) and activated MS 4 Å (300 mg) in anhydrous CH2Cl2
at ꢀ15 ꢁC was added TMSOTf (15
m
L, 68
m
mol) under a N2 atmo-
11 (200 mg, 85%) as a white foamy solid. [
a
]
25 þ112 (c 0.3, CHCl3);
D
sphere. The mixture reaction was stirred at this condition for
40 min, and then neutralized with Et3N. The mixture was diluted
with CH2Cl2 (5 mL), filtered through a pad of Celite, and the filtrate
was concentrated. The residue was purified by silica gel column
1H NMR (600 MHz, CDCl3):
d
7.98 (d, J ¼ 7.2 Hz, 1 H, ArH), 7.87 (d,
J ¼ 7.2 Hz, 1 H, ArH), 7.85e7.78 (m, 2 H, ArH), 7.47e7.35 (m, 9 H,
ArH), 7.32e7.28 (m, 3 H, ArH), 7.08 (d, J ¼ 7.8 Hz, 2 H, ArH), 5.64 (d,
J ¼ 9.6 Hz, 1 H, H-1GalN), 5.54 (d, J ¼ 9.0 Hz, 1 H, -NHAc), 5.50 (s, 1 H,
0
chromatography (hexaneeethyl acetate 10:1 to 2:1) to yield 9
CHPh), 5.25 (s, 1 H, CHPh), 5.07 (d, J ¼ 3.0 Hz, 1 H, H-1GalN ),
0
0
25
(204 mg, 62%) as a white foamy solid. [
NMR (600 MHz, CDCl3):
a
]
-11 (c 0.2, CHCl3); 1H
4.701e4.58 (m, 4 H, H-2GalN, H-3GalN, H-2GalN , H-3GalN ), 4.42 (dd,
D
d
7.62 (d, J ¼ 7.8 Hz, 2 H, ArH), 7.43e7.35 (m,
J ¼ 12.0, 1.8 Hz, 1 H, H-6aGalN), 4.33 (d, J ¼ 2.4 Hz, 1 H, H-4GalN), 4.08
0
5 H, ArH), 7.07 (d, J ¼ 7.8 Hz, 2 H, ArH), 5.47 (s, 1 H, CHPh), 4.80 (dd,
J ¼ 10.2, 3.0 Hz, 1 H, H-3), 4.46 (d, J ¼ 9.6 Hz, 1 H, H-1), 4.38 (d,
J ¼ 12.0 Hz, 1 H, H-6a), 4.32 (d, J ¼ 3.0 Hz, 1 H, H-4), 4.01 (d,
J ¼ 12.0 Hz, 1 H, H-6b), 3.80 (t, J ¼ 10.2 Hz, 1 H, H-2), 3.55 (s, 1 H, H-
5), 2.34 (s, 3 H, -SPhCH3), 2.09 (s, 3 H, -OCCH3); 13C NMR (150 MHz,
(dd, J ¼ 12.0, 1.2 Hz, 1 H, H-6bGalN), 3.85 (d, J ¼ 1.2 Hz, 1 H, H-4GalN ),
0
3.68 (s, 1 H, H-5GalN), 3.62 (dd, J ¼ 12.6, 1.2 Hz, 1 H, H-6aG0 alN ), 3.34
0
(dd, J ¼ 12.6, 1.2 Hz, 1 H, H-6bGalN ), 3.00 (s, 1 H, H-5GalN ), 2.36 (s,
3 H, -SPhCH3), 1.93 (s, 3 H, -OCOCH3), 1.36 (s, 3 H, -NHCOCH3); 13C
NMR (150 MHz, CDCl3):
d
170.9 (C¼O), 170.0 (C¼O), 168.3 (C¼O),
CDCl3):
d
170.4 (C¼O), 138.8, 137.5, 134.8, 129.8, 129.2, 128.2, 126.5,
167.2 (C¼O), 138.6, 137.4, 137.2, 134.7, 134.6, 134.5, 131.4, 131.2,
101.0, 85.3, 74.0, 72.6, 69.5, 69.2, 58.1, 29.7, 21.3, 21.0; ESI-TOF HRMS
129.6, 129.5, 129.0, 128.4, 128.1, 126.6, 126.5, 126.2, 124.2, 123.1,
0
101.4 (CHPh), 100.7 (CHPh), 95.3 (C-1GalN ), 82.2 (C-1GalN), 72.8 (C-
0
m/z: Calcd for C22H23N3O5SK [M þ K]þ 480.0990; found, 480.1045.
4GalN ), 72.6 (C-3GalN), 71.3 (C-4GalN), 69.7 (C-5GalN), 69.6 (C-6GalN),
0
0
0
4.5. para-Tolyl 3-O-acetyl-2-azido-4,6-O-benzylidene-2-deoxy-
a-
69.3 (C-3GalN ), 68.4 (C-6GalN ), 63.1 (C-5GalN ), 50.5 (C-2GalN), 46.4 (C-
0
D-galactopyranosyl-(1 / 3)-4,6-O-benzylidene-2-deoxy-2-
2GalN ), 22.6 (-NHCOCH3) 21.3 (-SPhCH3), 20.9 (-COCH3); ESI-TOF
phthalimido-1-thio-
b-D-galactopyranoside (10)
HRMS m/z: Calcd for C45H45N2O12S [MþH]þ 837.2688; Found
837.2648; Calcd for C45H44N2O12SNa [MþNa]þ 859.2507; Found
859.2538.
To a stirred mixture of 4 (340 mg, 0.68 mmol), and activated MS
4 Å (500 mg) in anhydrous toluene and 1,4-dioxane (v/v 1:1, 5 mL)
at ꢀ15 ꢁC was added TMSOTf (15
m
L, 82
m
mol) under a N2 atmo-
4.7. para-Tolyl 2-acetamido-4,6-O-benzylidene-2-deoxy-
galactopyranosyl-(1 / 3)-4,6-O-benzylidene-2-deoxy-2-
phthalimido-1-thio- -D-galactopyranoside (12)
a-D-
sphere. After the mixture was stirred at these temperature for 1 h, a
solution of 5 (390 mg, 0.82 mmol) in anhydrous toluene and 1,4-
dioxane (v/v 1:1, 5 mL) was added dropwise at 0 ꢁC under a N2
atmosphere. The mixture reaction was stirred at these conditions
for another 1 h, and then neutralized with Et3N. The mixture was
b
To a solution of 11 (200 mg, 0.24 mmol) in MeOH (5 mL) was
added NaOMe (0.5 M in MeOH) dropwise until the pH value

N. Bi et al. / Carbohydrate Research 451 (2017) 1e11
7
reached 10. The mixture was stirred at rt for 30 min and neutralized
4.9. 3-Azidopropyl 2,3-di-O-benzoyl-4-O-chloroacetyl-
rhamnopyranosyl-(1 / 3)- 2-acetamido-4,6-O-benzylidene-2-
deoxy- -D-galactopyranosyl-(1 / 3)-4,6-O-benzylidene-2-deoxy-
2-phthalimido- -D-galactopyranoside (13)
a-L-
with Amberlite IR 120 (Hþ). The solution was filtered, and the
filtrate was concentrated. The residue was purified by silica gel
column chromatography (hexaneeethyl acetate 1:2) to give 12
a
b
(170 mg, 90%) as a white foamy solid. [
NMR (600 MHz, CDCl3):
a
]
25 þ145 (c 0.2, CHCl3); 1H
D
d
7.93e7.70 (m, 4 H, ArH), 7.46e7.41 (m,
To a stirred mixture of 3 (105 mg, 0.085 mmol), 3-azidopropanol
(50 L, 0.49 mmol), and activated MS 4 Å (200 mg) in anhydrous
4 H, ArH), 7.40e7.36 (m, 5 H, ArH), 7.32e7.28 (m, 3 H, ArH), 7.09 (t,
J ¼ 10.4 Hz, 2 H, ArH), 5.81 (d, J ¼ 9.0 Hz, 1 H, -NHAc), 5.60 (d,
m
CH2Cl2 (4 mL) were added NIS (30 mg, 0.13 mmol) and TMSOTf
J ¼ 9.6 Hz, 1 H, H-1GalN), 5.53 (s, 1 H, CHPh), 5.29 (s, 1 H, CHPh), 5.03
(15
m
L, 0.06 mmol) at ꢀ40 ꢁC under a N2 atmosphere. The mixture
0
(d, J ¼ 3.6 Hz, 1 H, H-1GalN ), 4.70 (dd, J ¼ 10.8, 3.0 Hz, 1 H, H-3GalN),
was stirred at ꢀ40 ꢁC for 30 min and then slowly warmed up to rt
and stirred for another 1 h. The mixture was neutralized with Et3N,
and then diluted with CH2Cl2 (20 mL) and washed with saturated
aq. Na2S2O3 (10 mL) and brine (10 mL). The organic phase was dried
over anhydrous Na2SO4 and concentrated. The residue was purified
by silica gel column chromatography (hexaneeethyl acetate 5:1 to
4.67 (dd, J ¼ 10.8, 9.6 Hz, 1 H, H-2GalN), 4.40 (d, J ¼ 12.6 Hz, 1 H, H-
6aGalN), 4.34 (d, J ¼0 3.0 Hz, 1 H, H-4GalN), 4.30 (ddd, J ¼ 10.8, 9.0,
3.6 Hz, 1 H, H-2GalN ), 4.07 (d, J ¼ 12.6 Hz, 1 H, H-6bGalN), 3.71 (d,
0
J ¼ 3.6 Hz, 1 H, H-4GalN ), 3.65 (s, 1 H, H-5GalN), 3.62 (d, J 0¼ 12.0 Hz,
0
1 H, H-6aGalN ), 3.44 (dt, 0J ¼ 10.2, 3.0 Hz, 1 H, H-3GalN ), 3.30 (d,
0
J ¼ 12.0 Hz, 1 H, H-6bGalN ), 2.95e2.89 (m, 2 H, H-5GalN , -OH), 2.36
1:2) to give 13 (78 mg, 76%) as a white syrup solid. [
a
]
25 þ12 (c 0.2,
D
(s, 3 H, -SPhCH3), 1.39 (s, 3 H, -NHCOCH3); 13C NMR (150 MHz,
CHCl3); 1H NMR (600 MHz, CDCl3):
d
8.00 (d, J ¼ 7.2 Hz, 2 H, ArH),
CDCl3):
d
171.9 (C¼O), 168.192 (C¼O), 167.1 (C¼O), 138.6, 137.3,
7.94 (d, J ¼ 6.6 Hz, 1 H, ArH), 7.86 (d, J ¼ 7.2 Hz, 1 H, ArH), 7.80 (d,
J ¼ 7.2 Hz, 2 H, ArH), 7.79e7.74 (m, 2 H, ArH), 7.61e7.56 (m, 3 H,
ArH), 7.48e7.40 (m, 7 H, ArH), 7.37 (t, J ¼ 7.2 Hz,1 H, ArH), 7.34e7.27
(m, 5 H, ArH), 5.69 (d, J ¼ 9.0 Hz, 1 H, -NHAc), 5.58 (s, 1 H, CHPh),
5.46e5.41 (m, 2 H, H-2Rha, H-3Rha), 5.31e5.026 (m, 3 H, CHPh, H-
137.2, 134.73, 134.67, 134.4, 131.4, 131.2, 129.7, 129.6, 129.1, 128.5,
128.2, 126.7,0126.6, 126.2, 123.9, 123.2, 101.5 (CHPh), 101.0 (CHPh),
0
95.1 (C-1GalN ), 82.40 (C-1GalN) 75.0 (C-4GalN ), 72.2 (C-3GalN0 ), 71.3 (C-
0
4GalN0), 69.7 (C-5GalN), 69.6 (C-6), 69.2 (C-3GalN ), 68.4 (C-6 ), 63.6 (C-
0
5GalN ), 50.6 (C-2GalN), 49.7 (C-2GalN ), 22.5 (-NHCOCH3), 21.3
(-SPhCH3); ESI-TOF HRMS m/z: Calcd for C43H43N2O11S [MþH]þ
795.2582; Found 795.2561.
1GalN, H-4Rha), 5.15 (d, J ¼ 3.6 Hz, 1 H, H-1GalN ), 4.92 (s, 1 H, H-1Rha),
0
4.75 (dt, J ¼ 9.6, 3.6 Hz, 1 H, H-2GalN ), 4.71e4.68 (m, 2 H, H-2GalN, H-
3GalN), 4.37 (d, J ¼ 11.4 Hz, 1 H, H-6aGalN), 4.33 (br s, 1 H, H-4GalN),
4.23e4.16 (m, 1 H, H-5Rha), 4.14 (d, J ¼ 11.4 Hz, 1 H, H-6bGalN), 3.98
0
4.8. para-Tolyl 2,3-di-O-benzoyl-4-O-chloroacetyl-
rhamnopyranosyl-(1 / 3)-2-acetamido-4,6-O-benzylidene-2-
deoxy- -D-galactopyranosyl-(1 / 3)-4,6-O-benzylidene-2-deoxy-
2-phthalimido-1-thio- -D-galactopyranoside (3)
a-L-
(d, J ¼ 3.0 Hz, 1 H, H-4GalN ), 3.98e3.93 (m, 1 H, -OCH2CH2-), 3.86,
3.82 (2 d, J ¼ 14.4 Hz, 2 H, -OCOCH2Cl), 3.64 (d, J ¼ 12.0 Hz, 1 H, H0-
0
a
6aGalN ), 3.61 (s, 1 H, H-5GalN), 3.59e3.50 0 (m, 2 H, H-3GalN
,
b
-OCH2CH2-), 3.32 (d, J ¼ 12.0 Hz, 1 H, H-6bGalN ), 3.23e3.11 (m, 2 H,
0
-CH2CH2N3), 3.00 (s,
1
H, H-5GalN ), 1.81e1.74 (m,
1
H,
TMSOTf (10
m
L, 55
m
mol) was added to a stirred mixture of 12
-OCH2CH2CH2N3), 1.73e1.66 (m, 1 H, -OCH2CH2CH2N3), 1.64 (s, 3 H,
(152 mg, 0.19 mmol), 6 (132 mg, 0.22 mmol), and activated MS 4 Å
(300 mg) in anhydrous CH2Cl2 (5 mL) at 0 ꢁC under a N2 atmo-
sphere. The mixture was stirred at 0 ꢁC for 1 h, and then neutralized
with Et3N. The mixture was diluted with CH2Cl2 (15 mL), filtered
through a pad of Celite, and the filtrate was concentrated. The
resulting residue was purified by silica gel chromatography (hex-
-NHCOCH3), 0.95 (d, J ¼ 6.6 Hz, 3 H, H-6Rha); 13C NMR (150 MHz,
CDCl3):
d
170.5 (C¼O), 168.2 (C¼O), 167.7 (C¼O), 166.7 (C¼O), 165.3
(C¼O), 164.8 (C¼O), 137.3, 137.0, 134.69, 134.67, 133.5, 133.1, 131.28,
131.26, 129.8, 129.6, 129.5, 129.22, 129.18, 129.1, 128.6, 128.5, 128.3,
128.2, 126.5, 126.1, 123.9, 123.2, 101.5 (CHPh), 101.0 (CHPh), 98.6 (C-
0
0
0
1Rha), 98.2 (C-1GalN), 96.2 (C-1GalN ), 77.9 (C-3GalN ), 74.4 (C-4GalN ),
aneeethyl acetate 2:1 to 1:2) to yield 3 (168 mg, 72%) as a white
72.7 (C-4Rha), 72.3 (C-3GalN), 71.7 (C-4GalN), 70.5 (C-2Rha), 69.7 (C-
0
25
foamy solid. [
a
]
þ8 (c 0.25, CHCl3); 1H NMR (600 MHz, CDCl3):
3Rha), 69.3 (C-6GalN), 68.6 (C-6G0 alN ), 66.6 (C-5Rha), 66.5 (C-5GalN),
D
d
8.00 (d, J ¼ 8.4 Hz, 2 H ArH), 7.94 (d, J ¼ 6.6 Hz, 1 H, ArH), 7.87 (d,
66.0 (-OCH2C0H2-), 63.2 (C-5GalN ), 52.1 (C-2GalN), 48.1 (-CH2CH2N3),
47.0 (C-2GalN ), 40.5 (-OCOCH2Cl), 28.8 (-OCH2CH2CH2N3), 22.8
(-NHCOCH3), 17.4 (C-6Rha); ESI-TOF HRMS m/z: Calcd for
J ¼ 7.2 Hz, 1 H, ArH), 7.82e7.76 (m, 4 H, ArH), 7.60 (t, J ¼ 7.2 Hz, 1 H,
ArH), 7.50e7.38 (m, 12 H, ArH), 7.34e7.27 (m, 5 H, ArH), 7.10 (d,
J ¼ 7.8 Hz, 2 H, ArH), 5.68e5.61 (m, 2 H, H-1GalN, -NHAc), 5.53 (s,1 H,
C
61H61ClN5O19 [MþH]þ 1202.3644; Found 1202.3631; Calcd for
CHPh), 5.43e5.38 (m, 2 H, H-2Rha, H-3Rha), 5.27 (d, J ¼ 10.2 Hz, 1 H,
C61H60ClN5O19Na [MþNa]þ 1224.3463; Found 1224.3421; Calcd for
0
H-4Rha), 5.26 (s, 1 H, CHPh), 5.11 (d, J ¼ 4.2 Hz, 1 H, H-1GalN ), 4.88 (s,
0
C
61H60ClN5O19K [MþK]þ 1240.3203; Found 1240.3205.
1 H, H-1Rha), 4.70 (dt, J ¼ 10.2, 4.2 Hz, 1 H, H-2GalN ), 4.69e4.65 (m,
2 H, H-2GalN, H-3GalN), 4.42 (d, J ¼ 12.0 Hz, 1 H, H-6aGalN), 4.33 (d,
4.10. 3-Azidopropyl
a-L-rhamnopyranosyl-(1 / 3)-2-acetamido-
J ¼ 3.0 Hz, 1 H, H-4GalN), 4.21e4.14 (m, 1 H, H-5Rha), 4.09 (d,
2-deoxy- -D-galactopyranosyl-(1 / 3)-2-acetamido-2-deoxy-b
a
-D-
0
J ¼ 12.0 Hz, 1 H, H-6bGalN), 3.92 (d, J ¼ 3.0 Hz, 1 H H-4GalN ), 3.86,
galactopyranoside (1)
3.82 (2 d, J ¼ 14.4 Hz, 2 H, -OCOCH2Cl), 3.69 (s, 1 H, H-5GalN), 3.53 (d,
0
0
J ¼ 12.0 Hz, 1 H, H-6aGalN ), 3.49 (dd, J ¼ 10.8, 3.0 Hz, 1 H,0 H-3GalN ),
A solution of 13 (20 mg, 16.6 mmol) in ethanol (4 mL) and 80%
0
3.23 (d, J ¼ 12.0 Hz, 1 H, H-6bGalN ), 2.91 (s, 1 H, H-5GalN ), 2.36 (s,
hydrazine hydrate (1 mL) was refluxed for 6 h. The reaction mixture
was then concentrated and purified by size exclusion chromatog-
raphy on a Bio-Gel LH-20 column with methanol as the eluent to
get a white solid. The product was dissolved in pyridine (5 mL)
containing acetic anhydride (2 mL). The reaction mixture was
stirred at rt for 4 h and then concentrated to give a pale yellow
solid, which was then dissolved in 80% HOAc (5 mL) and stirred at
80 ꢁC for overnight. The reaction mixture was then co-evaporated
with toluene (2 ꢂ 5 mL), and the resulting product was then dis-
solved MeOH (4 mL) followed by addition of NaOMe (0.5 M) in
MeOH until the pH value reached 10. The mixture was stirred at rt
for 3 h, and neutralized with Amberlite IR 120 (Hþ). The solution
was filtered, and the filtrate was concentrated. The resulting
3 H, -SPhCH3), 1.63 (s, 3 H, -NHCOCH3), 0.94 (d, J ¼ 6.6 Hz, 3 H, H-
6Rha); 13C NMR (150 MHz, CDCl3):
d
170.5 (C¼O), 168.0 (C¼O), 167.2
(C¼O), 166.7 (C¼O), 165.3 (C¼O), 164.8 (C¼O), 138.5, 137.3, 137.0,
134.69, 134.65, 134.5, 133.5, 133.1, 131.4, 131.2, 129.8, 129.64, 129.58,
129.21, 129.16, 129.15, 128.6, 128.5, 128.3, 128.2, 126.7, 126.4, 126.1,
123.9, 123.3, 101.6 (CHPh), 101.0 (CHPh), 98.5 (C-1Rha), 96.1 (C-
0
0
0
1GalN ), 82.1 (C-1GalN), 77.8 (C-3GalN ), 74.4 (C-4GalN ), 73.1 (C-3GalN),
72.7 (C-4Rha), 71.6 (C-4GalN), 70.5 (C-2Rha), 69.8 (C-5GalN), 69.7 (C-
0
0
3Rha), 69.5 (C-6GalN), 68.5 (C-6GalN ), 66.5 (C-5Rha), 63.1 (C-5GalN ),
0
50.6 (C-2GalN), 46.9 (C-2GalN ), 40.5 (-OCOCH2Cl), 22.8 (-NHCOCH3),
21.3 (-SPhCH3), 17.4 (C-6Rha); ESI-TOF HRMS m/z: Calcd for
C
65H62ClN2O18S [MþH]þ 1225.3401; Found 1225.3376.

8
N. Bi et al. / Carbohydrate Research 451 (2017) 1e11
residue was purified by size exclusion chromatography on a
4.12. 3-Azidopropyl 2,3-O-isopropylidene-a-L-rhamnopyranoside
Sephadex G-10 column with distilled water as the eluent and then
(15)
lyophilized to give 1 (8.4 mg, 75%) as a white solid. [
a
]
25 þ13 (c 0.02,
D
H2O); 1H NMR (600 MHz, D2O):
d
4.90 (d, J ¼ 3.0 Hz, 1 H, H-1GalN ),
To a stirred mixture of 7 (108 mg, 0.28 mmol), 3-azidopropanol
(140 L, 1.40 mmol), and activated MS 4 Å (250 mg) in anhydrous
CH2Cl2 (4 mL) were added NIS (75 mg, 0.34 mmol) and TMSOTf
4.67 (s, 1 H, H-1Rha), 4.35 (d,0 J ¼ 8.4 Hz, 1 H, H-1GalN), 4.20 (dd,
J ¼ 10.8, 3.6 Hz, 1 H, H-2GalN ), 3.97 (d, J ¼ 3.0 Hz, 1 H, H-4GalN),
3.90e3.86 (m, 2 H), 3.84e3.80 (m, 1 H), 3.69e3.55 (m, 10 H),
3.55e3.49 (m, 1 H), 3.48e3.44 (m, 1 H), 3.25 (t, J ¼ 9.6 Hz, 1 H), 3.21
(t, J ¼ 6.6 Hz, 2 H, -CH2CH2N3), 1.90, 1.85 (2 s, 2 ꢂ 3 H, 2 ꢂ -
NHCOCH3), 1.71e1.64 (m, 2 H, -OCH2CH2CH2N3), 1.08 (d, J ¼ 6.0 Hz,
m
(5
m
L, 0.03 mmol) at ꢀ40 ꢁC under a N2 atmosphere. The reaction
mixture was stirred for 1 h, and neutralized with Et3N. The mixture
was diluted with CH2Cl2 (10 mL), filtered through a pad of Celite,
and the filtrate was washed with saturated aq. Na2S2O3 (10 mL) and
brine (10 mL), respectively. The organic phase was dried over
anhydrous Na2SO4, filtered, and concentrated. The above obtained
residue was dissolved into methanol (4 mL), and NaOMe (0.5 M) in
MeOH was added until the pH value reached 10. The resulting
mixture was stirred for 30 min and then neutralized with Amberlite
IR 120 (Hþ). The solution was filtered, and the filtrate was
concentrated. The residue was purified by silica gel column chro-
3 H, H-6Rha); 13C NMR (150 MHz,0 D2O):
d 174.33, 174.30, 102.2 (C-
1Rha), 101.0 (C-1GalN), 93.1 (C-1GalN ), 76.0, 74.9, 74.2, 71.8, 71.4, 70.2,
69.8, 69.1, 68.0, 67.0, 63.1, 60.9, 60.7, 50.6, 48.1, 47.7, 28.0, 22.1, 21.8,
16.5; ESI-TOF HRMS m/z: Calcd for C25H44N5O15 [MþH]þ 654.2828;
Found 654.2876; Calcd for C25H43N5O15Na [MþNa]þ 676.2648;
Found 676.2686.
4.11. 3-Azidopropyl 2,3-di-O-benzoyl-
(1 / 3)-2-acetamido-4,6-O-benzylidene-2-deoxy-
galactopyranosyl-(1 / 3)-4,6-O-benzylidene-2-deoxy-2-
phthalimido- -D-galactopyranoside (14)
a
-L-rhamnopyranosyl-
matography (hexaneeethyl acetate 3:1) to give 15 (42 mg, 53%) as a
25
a-D-
white foamy solid. [
CDCl3):
a
]
-27 (c 0.4, CHCl3); 1H NMR (600 MHz,
D
d
4.95 (s,1 H, H-1), 4.12 (d, J ¼ 5.4 Hz,1 H, H-2), 4.09e4.04 (t,
b
J ¼ 6.6 Hz, 1 H, H-3), 3.82e3.77 (m, 1 H, -OCH2CH2-), 3.66e3.59 (m,
1 H, H-5), 3.53e3.48 (m, 1 H, -OCH2CH2-), 3.42e3.36 (m, 3 H, H-4,
-CH2CH2N3), 2.40 (d, J ¼ 4.2 Hz, 1 H, -OH), 1.92e1.80 (m, 2 H,
-OCH2CH2CH2N3), 1.52 [s, 3 H, -C(CH3)2], 1.35 [s, 3 H, -C(CH3)2], 1.29
To a solution of 13 (70 mg, 0.058 mmol) in CH2Cl2/CH3OH (v/v
1:4, 5 mL) at rt were added thiourea (13 mg, 0.17 mmol) and 2,6-
lutidine (2
mL). The reaction mixture was refluxed for 6 h, at
(d, J ¼ 6.6 Hz, 3 H, H-6); 13C NMR (150 MHz, CDCl3):
d
109.5, 97.1,
which point TLC (hexaneeethyl acetate 1:2) showed the complete
disappearance of 13, and the solvent was then removed under
reduced pressure. The resulting residue was dissolved in CH2Cl2
(20 mL) and washed successively with 1M HCl, water and brine. The
organic layer was dried over Na2SO4, filtered and concentrated.
Purification of the residue on size exclusion chromatography on a
Bio-Gel LH-20 column with methanol as the eluent to generate a
colorless syrup, which was further purified on a silica gel column
chromatography (hexaneeethyl acetate 1:2) gave 14 (52 mg, 80%)
78.3, 75.8, 74.5, 65.8, 64.2, 48.34, 28.8, 28.0, 26.2, 17.4.
4.13. 3-Azidopropyl 2,3-di-O-benzoyl-4-O-chloroacetyl-
a-L-
rhamnopyranosyl-(1 / 3)-2-acetamido-4,6-O-benzylidene-2-
deoxy- -D-galactopyranosyl-(1 / 3)-4,6-O-benzylidene-2-deoxy-
2-phthalimido- -D-galactopyranosyl-(1 / 4)-2,3-O-
isopropylidene- -L-rhamnopyranoside (16)
a
b
a
After a mixed solution of 3 (20 mg, 0.016 mmol), 15 (13 mg,
0.045 mmol), and activated MS 4 Å (200 mg) in anhydrous CH2Cl2
(5 mL) was stirred at rt for 1 h under a N2 atmosphere, it was cooled
as a white foamy solid. [
CD3CN):
a
]
25 þ148 (c 0.2, CHCl3); 1H NMR (600 MHz,
D
d
7.98 (d, J ¼ 8.4 Hz, 2 H, ArH), 7.92 (t, J ¼ 6.6 Hz, 1 H, ArH),
7.90 (d, J ¼ 7.2 Hz, 1 H, ArH), 7.89e7.84 (m, 2 H, ArH), 7.83 (d,
J ¼ 7.8 Hz, 2 H, ArH), 7.72 (dd, J ¼ 6.0, 3.6 Hz, 1 H, ArH), 7.69 (t,
J ¼ 7.2 Hz,1 H, ArH), 7.62 (dd, J ¼ 6.0, 3.6 Hz,1 H, ArH), 7.58e7.52 (m,
4 H, ArH), 7.46e7.33 (m, 9 H, ArH), 6.10 (d, J ¼ 9.0 Hz, 1 H, -NHAc),
5.73 (s,1 H, CHPh), 5.43 (s,1 H, CHPh), 5.34 (br dd, J ¼ 3.6,1.8 Hz,1 H,
to ꢀ40 ꢁC, and NIS (5 mg, 0.02 mmol) and AgOTf (2 mg, 7.7
mmol)
were then added. The reaction mixture was stirred ꢀ40 ꢁC for
30 min and slowly warmed to 0 ꢁC and stirred for another 1 h, and
then neutralized with Et3N. The resulting mixture was diluted with
CH2Cl2 (10 mL), filtered through a pad of Celite, and the filtrate was
washed with saturated aq. Na2S2O3 (10 mL) and brine (10 mL). The
organic phase was dried over Na2SO4 and concentrated. The residue
was purified by flash column chromatography (hexaneeethyl ac-
H-2Rha), 5.22 (d, J ¼ 8.4 Hz, 1 H, H-1GalN), 5.12 (d, J ¼ 4.2 Hz, 1 H, H-
0
1GalN ), 5.08 (dd, J ¼ 9.6, 3.6 Hz, 1 H, H-3Rha), 4.90 (br s, 1 H, H-1Rha),
4.79 (dd, J ¼ 11.4, 3.6 Hz, 1 H, H-3GalN), 4.49 (d, J ¼ 3.6 Hz, 1 H, H-
4GalN)0 , 4.45 (dd, J ¼ 11.4, 8.4 Hz, 1 H, H-2GalN), 4.40e4.35 (m, 1 H, H-
etate 1:2) to give 16 (19 mg, 82%) as a white foamy solid. [
a
]
25 þ141
D
2GalN ), 4.22, 4.18 (2 d, J ¼ 12.0 Hz, 2 ꢂ 1 H, H-6a,bGalN), 4.12 (d,
(c 0.2, CHCl3); 1H NMR (600 MHz, CDCl3):
d
7.99 (d, J ¼ 7.8 Hz, 2 H,
0
J ¼ 3.0 Hz, 1 H, H-4GalN ), 3.92e3.84 (m, 2 H, -OCH2CH2-, H-5Rha),
ArH), 7.91 (d, J ¼ 7.8 Hz, 1 H, ArH), 7.84 (d, J ¼ 6.0 Hz, 1 H, ArH), 7.80
(d, J ¼ 8.4 Hz, 2 H, ArH), 7.78e7.72 (m, 2 H, ArH), 7.58 (d, J ¼ 7.8 Hz,
3 H, ArH), 7.48e7.41 (m, 7 H, ArH), 7.38 (t, J ¼ 7.2 Hz, 1 H, ArH),
3.76e3.70 (m, 2 H, H-4Rha, H-5GalN), 3.63 (dd, J ¼ 11.4, 3.0 Hz, 1 H, H-
0
3GalN ), 3.56e3.51 (m, 1 H, -OCH2CH2-), 3.47 (d, J ¼ 4.8 Hz, 1 H, -OH),
0
3.44e3.37 (m, 2 H, H-6a,bGalN ), 3.19e3.07 (m, 3 H, -CH2CH2N3, H-
7.33e7.27 (m, 5 H, ArH), 5.78 (d, J 0¼ 9.6 Hz, 1 H, -NHAc), 5.57 (s, 1 H,
0
0
CHPh), 5.45e5.40 (m, 2 H, H-2Rha , H-3Rha ), 5.37 (d, J ¼ 9.0 Hz, 1 H,
0
5GalN ), 1.75e1.65 (m, 2 H, -OCH2CH2CH2N3), 1.65 (s, 3 H, -COCH3),
1.22 (d, J ¼ 6.0 Hz, 3 H, H-6Rha); 13C NMR (150 MHz, CD3CN):
d
169.8
H-1GalN), 5.29 (s, 1 H, CHPh), 5.28 (d, J ¼ 10.2 Hz, 1 H, H-4Rha ), 5.16
0
0
(C¼O), 168.3 (C¼O), 168.0 (C¼O), 165.4 (C¼O), 165.1 (C¼O), 138.4,
138.3, 134.9, 134.8, 133.6, 133.2, 131.4, 131.3, 131.2, 129.8, 129.6,
129.5, 129.3, 129.00, 128.97, 128.8, 128.7, 128.4, 128.2, 126.3, 126.1,
123.6, 123.2, 100.5 0(CHPh), 100.4 (CHPh), 99.6 (C-1Rha), 98.3 (C-
(d, J ¼ 3.6 Hz, 1 H, H-1GalN ), 4.95 (s, 1 H, H-1Rha ), 4.91 (dd, J ¼ 11.4,
3.6 Hz, 1 H, 0H-3GalN), 4.83 (s, 1 H, H-1Rha), 4.74 (dt, J ¼ 10.2, 3.6 Hz,
1 H, H-2GalN ), 4.62 (dd, J ¼ 11.4, 8.4 Hz, 1 H, H-2GalN), 4.304e4.30 (m,
2 H, H-4GalN, H-6aGalN), 4.23e4.17 (m, 1 H, H-5Rha ), 4.14 (d,
0
0
0
1GalN), 97.3 (C-1GalN ), 76.0 (C-3GalN ), 74.8 (C-4GalN ), 73.1 (C-3GalN),
72.5 (C-3Rha), 72.2 (C-4GalN), 70.3 (C-2Rha0), 70.2 (C-4Rha), 68.91 (C-
J ¼ 11.4 Hz, 1 H, H-6bGalN), 4.01 (d, J ¼ 3.0 Hz, 1 H, H-4GalN ),
3.88e3.80 (m, 3 H, -OCOCH2Cl, H-2Rha), 3.74 (t, J ¼ 3.0 Hz, 1 H, H0-
5Rha), 68.88 (C-6GalN), 68.1 (C-6GalN ), 66.4 (C-5GalN), 66.2
3Rha), 3.72e3.67 (m, 1 H, -OCH2CH2-), 3.65e3.61 (m, 2 H, H-3GalN
,
0
0
(-OCH2CH2-), 63.3 (C-5GalN ), 52.2 (C-2GalN), 47.8 (-CH2CH2N3), 47.6
H-5GalN), 3.58 (m, 2 H, H-6aGalN , H-5Rha), 3.44e3.38 (m, 1 H,
0
0
(C-2GalN ), 28.4 (-OCH2CH2CH2N3), 22.2 (-COCH3), 17.1 (C-6Rha); ESI-
-OCH2CH2-), 3.35e3.28 (m, 4 H, H-4Rha, H-6bGalN , -CH2CH2N3), 3.04
0
TOF HRMS m/z: Calcd for C59H60N5O18 [MþH]þ 1126.3928; Found
1126.3914; Calcd for C59H59N5O18Na [MþNa]þ 1148.3747; Found
1148.3711; Calcd for C59H59N5O18K [MþK]þ 1164.3487; Found
1164.3503.
(s, 1 H, H-5GalN ), 1.82e1.75 (m, 2 H, -OCH2CH2CH2N3), 1.65 (s, 3 H,
-COCH3), 1.36 [s, 3 H, -C(CH3)2], 1.34 (d, J ¼ 6.6 Hz, 3 H, H-6Rha), 0.96
0
(d, J ¼ 6.0 Hz, 3 H, H-6Rha ), 0.83 [s, 3 H, -C(CH3)2]; 13C NMR
(150 MHz, CDCl3):
d
170.6 (C¼O), 168.3 (C¼O), 168.0 (C¼O), 166.8

N. Bi et al. / Carbohydrate Research 451 (2017) 1e11
9
25
(C¼O), 165.3 (C¼O), 164.8 (C¼O), 137.4, 137.0, 134.1, 134.1, 133.5,
white foamy solid. [
a
]
þ96 (c 0.2, CHCl3); 1H NMR (600 MHz,
D
133.1, 132.2, 131.5, 129. 8, 129.7, 129.6, 129.2, 129.2, 129.1, 128.6,
128.5, 128.3, 128.2, 126.5, 126.1, 123.7, 122.6, 109.0 [0-C(CH3)2], 101.6
(-CHPh), 101.0 (-CHPh), 100.2 (C-1GalN), 98.6 (C-1Rha ), 96.7 (C-1Rha),
CDCl3): d 7.95e7.76 (m, 4 H, ArH), 7.57e7.53 (m, 2 H, ArH),
7.44e7.36 (m, 5 H, ArH), 7.33e7.29 (m, 3 H, ArH), 5.88 (d, J ¼ 8.4 Hz,
1 H, -NHAc), 5.57 (s, 1 H, CHPh), 5.32 (s, 1 H, CHPh), 5.26 (d,
0
0
0
96.5 (C-1GalN ), 84.2 (C-4Rha), 77.8 (C-3GalN ), 77.5 (C-3GalN), 75.7 (C-
J ¼ 8.4 Hz, 1 H, H-1GalN), 5.07 (d, J ¼ 3.6 Hz, 1 H, H-1GalN ), 4.73 (dd,
0
0
2Rha), 74.5 (C-4GalN ), 72.7 (C-4Rha ), 72.1 (C-3GalN), 71.7 (C-4GalN),
J ¼ 10.8, 3.6 Hz, 1 H, H-3GalN), 4.67 (dd, J ¼ 10.8, 8.4 Hz, 1 H, H-2GalN),
0
70.6 (C-2Rha), 69.7 (C-3Rha), 69.4 (C-6GalN), 68.6 (C-6GalN ), 66.5 (C-
0
0
4.39e4.31 (m, 3 H, H-2GalN , H-4GalN, H-6aGalN), 4.14 (dd, J ¼ 12.6,
5Rha ), 66.1 (C-5GalN), 64.5 (C-5Rha), 64.1 (-OCH2CH2-), 63.0 (C-
1.8 Hz, 1 H, H-6bGalN),0 3.99e3.93 (m, 1 H, -OCH2CH2-), 3.78 (d,
0
0
0
5GalN ), 52.8 (C-2GalN), 48.3 (-CH2CH2N3), 47.1 (C-2GalN ), 40.5
J ¼ 3.0 Hz, 1 H, H-4GalN ), 3.74 (dd, J ¼ 12.6, 1.2 Hz, 1 H, H-6aGalN ),
(-OCOCH2Cl), 28.8 (-OCH2CH2CH2N3), 27.7 [-C(CH3)2], 25.7
3.60 (d, J ¼ 1.2 Hz,1 H, H-5GalN), 3.58e3.53 (m,1 H, -OCH2CH2-), 3.51
0
0
[-C(CH3)2], 22.8 (-COCH3), 17.6 (C-6Rha), 17.4 (C-6Rha ); ESI-TOF
(dt, J ¼ 9.6, 3.0 Hz, 1 H, H-3GalN ), 3.41 (dd, J ¼ 12.6, 1.8 Hz, 1 H, H-
0
0
HRMS m/z: Calcd for C70H75ClN5O23 [MþH]þ 1388.4536; Found
6bGalN ), 3.23e3.14 (m, 2 H, -CH2CH2N3), 3.02 (s, 1 H, H-5GalN ), 2.97
(d, J ¼ 9.6 Hz, 1 H, -OH), 1.83e1.74 (m, 1 H, -OCH2CH2CH2N3),
1.73e1.65 (m, 1 H, -OCH2CH2CH2N3), 1.42 (s, 3 H, -NHCOCH3); 13C
1388.4514.
4.14. 3-Azidopropyl 3-O-acetyl-4,6-O-benzylidene-2-acetamido-2-
NMR (150 MHz, CDCl3):
d
171.9 (C¼O), 168.3 (C¼O), 167.6 (C¼O),
deoxy-
2-phthalimido-
a
-D-galactopyranosyl-(1 / 3)-4,6-O-benzylidene-2-deoxy-
-D-galactopyranoside (17)
137.2, 134.74, 134.67, 131.24, 131.20, 129.6, 129.1, 128.6, 128.2, 126.4,
b
126.2, 123.9, 123.1, 101.5 (CHPh), 101.0 (CHPh), 98.2 (C-1GalN), 95.2
0
0
(C-1GalN ), 75.0 (C-4GalN ), 71.3 (C-4GalN), 71.2 (C-3GalN), 69.4 (C-
0
0
To a stirred mixture of 11 (110 mg, 0.13 mmol), 3-azidopropanol
(79 L, 0.78 mmol), and activated MS 4 Å (200 mg) in anhydrous
6GalN), 69.3 (C-3GalN ), 68.5 (C-6GalN ), 66.4 (C-5GalN), 66.0
0
0
m
(-OCH2CH2-), 63.6 (C-5GalN ), 52.0 (C-2GalN), 49.7 (C-2GalN ), 48.0
(-CH2CH2N3), 28.8 (-OCH2CH2CH2N3), 22.5 (-NHCOCH3); ESI-TOF
HRMS m/z: Calcd for C39H42N5O12 [MþH]þ 772.2824; Found
772.2822; Calcd for C39H41N5O12Na [MþNa]þ 794.2644; Found
794.2610.
CH2Cl2 (5 mL) were added NIS (35 mg, 0.15 mmol) and TMSOTf
(20
m
L, 0.09 mmol) at ꢀ40 ꢁC under a N2 atmosphere. The reaction
mixture was stirred at ꢀ40 ꢁC for 1 h, and slowly warmed up to rt
with stirring for another 1 h, and then neutralized with Et3N. The
mixture was then diluted with CH2Cl2 (20 mL), filtered through a
pad of Celite, and the filtrate was washed successively with satu-
rated aq. Na2S2O3 (20 mL) and brine (15 mL). The organic phase was
dried over anhydrous Na2SO4, filtered, and concentrated. The res-
idue was purified by silica gel column chromatography (hex-
4.16. 3-Azidopropyl 4-O-acetyl-2,3-O-isopropylidene-
rhamnopyranosyl-(1 / 3)- 2-acetamido-4,6-O-benzylidene-2-
deoxy- -D-galactopyranosyl-(1 / 3)-4,6-O-benzylidene-2-deoxy-
2-phthalimido- -D-galactopyranoside (20)
a-L-
a
b
aneeethyl acetate 10:1 to 1:2) to give 17 (74 mg, 69%) as a white
25
foamy solid. [
d
a
]
D
þ116 (c 0.2, CHCl3); 1H NMR (600 MHz, CDCl3):
After a mixed solution of 18 (45 mg, 0.058 mmol), 19 (25 mg,
0.071 mmol), and activated 4 Å MS (100 mg) in anhydrous CH2Cl2
(4 mL) was stirred at rt for 2 h under a N2 atmosphere, it was cooled
to ꢀ40 ꢁC, and then NIS (16 mg, 0.07 mmol) and AgOTf (4 mg,
0.015 mmol) were added. The reaction mixture was stirred ꢀ40 ꢁC
for 30 min and slowly warmed to 0 ꢁC and stirred for another 1 h,
and then neutralized with Et3N. The mixture was diluted with
CH2Cl2 (20 mL), filtered through a pad of Celite, and the filtrate was
washed successively with saturated aq. Na2S2O3 (20 mL) and brine
(15 mL). The organic phase was dried over anhydrous Na2SO4 and
concentrated. The residue was purified by flash column chroma-
tography (hexaneeethyl acetate 2:1 to 1:2) to give 20 (45 mg, 78%)
7.97 (d, J ¼ 7.2 Hz,1 H, ArH), 7.87 (d, J ¼ 7.2 Hz,1 H, ArH), 7.84e7.77
(m, 2 H, ArH), 7.56 (d, J ¼ 7.2 Hz, 2 H, ArH), 7.44e7.36 (m, 5 H, ArH),
7.34e7.29 (m, 3 H, ArH), 5.66 (d, J ¼ 9.0 Hz, 1 H, -NHAc), 5.56 (s, 1 H,
CHPh), 5.31 (d, J ¼ 7.8 Hz, 1 H, H-1GalN), 5.28 (s, 1 H, CHPh), 5.12 (d,
0
J ¼ 30.6 Hz, 1 H, H-1GalN ), 4.754e4.63 (m, 4 H, H-2GalN, H-3GalN, H-
0
2GalN , H-3GalN ), 4.38 (d, J ¼ 12.0 Hz, 1 H, H-6aGalN), 4.35 (d,
J ¼ 2.4 Hz, 1 H, H-4GalN), 4.16e4.12 (dd, J ¼ 12.0, 1.2 Hz, 1 H, H-
6bGalN), 3.99e3.94 (m, 1 H, -OCH2CH2-), 3.93 (d, J ¼ 3.0 Hz, 1 H, H-
0
0
4GalN ), 3.67 (dd, J ¼ 12.6,1.2 Hz,1 H, H-6aGalN ), 3.62 (s,1 H, H-5GalN),
3.59e3.53 (m, 1 H, -OCH2CH2-), 3.42 (dd, J ¼ 12.6, 1.2 Hz, 1 H, H-
0
0
6bGalN ), 3.24e3.14 (m, 2 H, -CH2CH2N3), 3.10 (s, 1 H, H-5GalN ), 1.95
(s, 3 H, -COCH3), 1.83e1.75 (m, 1 H, -OCH2CH2CH2N3), 1.74e1.66 (m,
1 H, -OCH2CH2CH2N3), 1.44 (s, 3 H, -NHCOCH3); 13C NMR (150 MHz,
as a white foamy solid. [
CDCl3):
a
]
25 þ15 (c 0.15, CHCl3); 1H NMR (600 MHz,
D
d
7.98e7.79 (m, 4 H, ArH), 7.56 (d, J ¼ 7.8 Hz, 2 H, ArH),
CDCl3):
d
171.0 (C¼O),170.0 (C¼O), 168.5 (C¼O), 167.8 (C¼O), 137.24,
7.45e7.37 (m, 5 H, ArH), 7.34e7.30 (m, 3 H, ArH), 5.65 (d, J ¼ 9.6 Hz,
137.20, 134.7, 134.6, 131.3, 131.2, 129.4, 129.0, 128.5, 128.1, 126.4,
1 H, -NHAc), 5.55 (s,1 H, CHPh), 5.33 (d, J ¼ 7.8 Hz,1 H, H-1GalN), 5.27
0
126.2, 124.1, 123.1, 101.40 (CHPh), 100.7 (CHPh), 98.2 (C-1GalN), 95.7
(s, 1 H, CHPh), 5.08 (d, J ¼ 3.6 Hz, 1 H, H-1GalN ), 4.91 (s, 1 H, H-1Rha),
0
(C-1GalN ), 72.9 (C-4GalN ), 71.9 (C-3GalN), 71.5 (C-4GalN), 69.4 (C-
4.72 (dd, J ¼ 9.6, 7.8 Hz,1 H, H-4Rha), 4.69 (dd, J ¼ 10.8, 7.8 Hz,1 H, H-
0
0
6GalN), 69.2 (C-3GalN ), 68.4 (C-6GalN ), 66.4 (C-5GalN), 66.0
2GalN), 4.65 (dd, J ¼ 10.8, 3.6 Hz, 1 H, H-3GalN), 4.58 (dt, J ¼ 10.8,
0
0
(-OCH2CH2-), 63.1 (C-5GalN ), 52.1 (C-2GalN), 48.1 (-CH2CH2N3), 46.6
3.6 Hz, 1 H, H-2GalN ), 4.37 (d, J ¼ 12.0 Hz, 1 H, H-6aGalN), 4.34 (br d,
0
(C-2GalN ), 28.8 (-OCH2CH2CH2N3), 22.7 (-OCOCH3), 20.9
J ¼ 3.0 Hz,1 H, H-4GalN), 4.14 (dd, J ¼ 12.0,1.2 Hz,1 H, H-6bGalN), 4.09
(-NHCOCH3); ESI-TOF HRMS m/z: Calcd for C41H44N5O13 [MþH]þ
814.2930; Found 814.2900; Calcd for C41H43N5O13Na [MþNa]þ
836.2750; Found 836.2727.
(dd, J ¼ 7.8, 5.4 Hz,1 H, H-3Rha), 4.00e3.94 (m,1 H, -OCH2CH2-), 3.91
0
(d, J ¼ 5.4 Hz, 1 H, H-2Rha), 3.85 (d, J ¼ 3.0 Hz, 1 H, H-4GalN ),
0
3.80e3.73 (m, 2 H, H-6aGalN , H-5Rha), 3.61 (s, 1 H, H-5GalN),
3.60e3.54 (m, 1 H, -OCH2CH2-), 3.42 (dd, J ¼010.8, 3.0 Hz, 1 H, H-
0
4.15. 3-Azidopropyl 4,6-O-benzylidene-2-acetamido-2-deoxy-
galactopyranosyl-(1 / 3)-4,6-O-benzylidene-2-deoxy-2-
phthalimido-b-D-galactopyranoside (18)
a
-D-
3GalN ), 3.38 (dd, J ¼ 12.0, 1.2 Hz,01 H, H-6bGalN ), 3.25e3.15 (m, 2 H,
-CH2CH2N3), 2.97 (s, 1 H, H-5GalN ), 2.00 (s, 3 H, -OCOCH3), 1.84e1.76
(m, 1 H, -OCH2CH2CH2N3), 1.75e1.66 (m, 1 H, -OCH2CH2CH2N3), 1.51
[s, 3 H, -C(CH3)2], 1.42 (s, 3 H, -NHCOCH3), 1.26 [s, 3 H, -C(CH3)2],
To a solution of 17 (70 mg, 0.086 mmol) in MeOH (3 mL) was
added NaOMe (0.5 M) in MeOH until the pH value reached 10. The
mixture was stirred at rt for 1 h, and then neutralized with
Amberlite IR 120 (Hþ). The solution was filtered, and the filtrate was
concentrated. The residue was purified by silica gel column chro-
matography (hexaneeethyl acetate 1:2) to give 18 (58 mg, 88%) as a
0.88 (d, J ¼ 6.0 Hz, 3 H, H-6Rha); 13C NMR (150 MHz, CDCl3):
d 170.2
(C¼O), 170.0 (C¼O), 168.3 (C¼O), 167.9 (C¼O), 137.3, 137.2, 134.9,
134.7, 131.3, 131.2, 129.6, 129.1, 128.5, 128.2, 126.5, 126.1, 124.1, 123.1,
109.6 [-C(CH3)2], 101.6 (CHPh), 100.9 (CHPh), 99.9 (C-1Rha), 98.1 (C-
0
0
1GalN), 95.2 (C-1GalN ), 77.5 (C-3GalN ), 75.9 (C-2Rha), 75.3 (C-3Rha),
0
75.0 (C-4GalN ), 74.1 (C-4Rha), 71.3 (2C, C-3GalN, C-4GalN), 69.3 (C-

10
N. Bi et al. / Carbohydrate Research 451 (2017) 1e11
0
6GalN), 68.6 (C-6GalN0 ), 66.4 (C-5GalN), 66.1 (-OCH2CH2-), 64.5 (C-
(15 mL). The organic phase was dried over Na2SO4 and concen-
trated. The residue was purified by flash column chromatography
(hexaneeethyl acetate 1:4) to give 22 (21 mg, 76%) as a white foamy
5Rha), 63.2 (C-5GalN ), 52.1 (C-2GalN), 48.1 (-CH2CH2N3), 47.1 (C-
0
2GalN ), 28.7 (-OCH2CH2CH2N3), 27.6 [-C(CH3)2], 26.3 [-C(CH3)2], 22.7
(-NHCOCH3), 21.0 (-OCOCH3), 17.0 (C-6Rha); ESI-TOF HRMS m/z:
Calcd for C50H58N5O17 [MþH]þ 1000.3822; Found 1000.3800; Calcd
for C50H57N5O17Na [MþNa]þ 1022.3642; Found 1022.3626.
solid. [
a]
25 þ98 (c 0.2, CHCl3); 1H NMR (600 MHz, CDCl3):
d 7.98 (d,
D
J ¼ 8.4 Hz, 2 H, ArH), 7.95e7.92 (m, 1 H, ArH), 7.88e7.84 (m, 2 H,
ArH), 7.82e7.76 (m, 5 H, ArH), 7.73e7.68 (m, 2 H, ArH), 7.59 (t,
J ¼ 7.8 Hz, 1 H, ArH), 7.56e7.50 (m, 4 H, ArH), 7.45 (t, J ¼ 7.8 Hz, 3 H,
ArH), 7.43e7.34 (m, 10 H, ArH), 7.34e7.26 (m, 8 H, ArH), 5.72 (d,
4.17. 3-Azidopropyl 2,3-O-isopropylidene-
(1 / 3)-2-acetamido-4,6-O-benzylidene-2-deoxy-
galactopyranosyl-(1 / 3)-4,6-O-benzylidene-2-deoxy-2-
phthalimido- -D-galactopyranoside (21)
a-L-rhamnopyranosyl-
a-D-
J ¼ 9.6 Hz, 1 H, -NHAc), 5.60 (d, J ¼ 10.2 Hz, 1 H, -NHAc), 5.54 (s, 1 H,
0
CHPh), 5.51 (s, 1 H, CHPh), 5.44e5.39 (m, 2 H, H-2,3Rha ), 5.35 (d,
00
b
J ¼ 8.4 Hz, 1 H, H-1GalN ), 5.33 (d, J ¼ 8.40 Hz, 1 H, H-1GalN), 5.28 (s,
1 H, CHPh), 5.27 (t, J ¼ 9.60H00 z, 1 H, H-4Rha ), 5.24 (s, 1 H, CHPh), 5.12
0
To a solution of 20 (40 mg, 0.04 mmol) in MeOH (2 mL) was
added NaOMe (0.5 M) in MeOH dropwise until the pH value
reached 10. The mixture was stirred at rt for 5 h and neutralized
with Amberlite IR 120 (Hþ). The solution was filtered, and the
filtrate was concentrated. The residue was purified by silica gel
column chromatography (hexaneeethyl acetate 1:4) to give 21
(33 mg, 85%) as a white foamy solid. [
NMR (600 MHz, CDCl3):
(d, J ¼ 3.6 Hz, 1 H, H-1GalN ), 5.03 (d, J ¼ 3.6 Hz, 1 H, H-1GalN ), 4.92
0
00
(d, J ¼ 1.2 Hz, 1 H, H-1Rha ), 4.86 (dd, J ¼ 10.8, 3.6 Hz, 1 H, H-3GalN ),
000
4.78 (s, 1 H, H-1Rha), 4.71 (dt, J ¼ 10.2, 3.6 Hz, 1 H, H-2GalN ), 4.66
(dd, J ¼ 11.4, 8.4 Hz, 1 H, H-2GalN), 4.62 (dd, J ¼ 11.4, 3.6 Hz, 1 H, H-
00
3GalN), 4.54 (dd, J ¼ 11.4, 8.4 Hz, 1 H, H-2GalN ), 4.48 (dt, J ¼ 10.2,
0
3.6 Hz, 1 H, H-2GalN ), 4.37 (d, J ¼ 12.6 Hz, 1 H, H-6a), 4.32 (d,
00
00
25
a]
þ65 (c 0.2, CHCl3); 1H
J ¼ 3.6 Hz, 1 H, H-4GalN), 4.30e4.26 (m, 2 H, H-4GalN , H-6aGalN00),
D
0
d
7.99e7.78 (m, 4 H, ArH), 7.56 (br d,
4.22e4.16 (m, 1 H, H-5Rha000), 4.14e4.09 (m, 2 H, H-6b, H-6bGalN ),
J ¼ 7.2 Hz, 2 H, ArH), 7.45e7.36 (m, 5 H, ArH), 7.33e7.28 (m, 3 H,
4.01e3.93 (m, 2 H, H-4GalN , -OCH2CH2-), 3.86, 3.82 (2 d, J ¼ 14.4 Hz,
0
ArH), 5.69 (d, J ¼ 9.6 Hz, 1 H, -NHAc), 5.55 (s, 1 H, CHPh), 5.33 (d,
2 H, -OCOCH2Cl), 3.77 (d, J ¼ 11.4 Hz, 1 H, H-6aGalN ), 3.73 (d,
0
J ¼ 7.8 Hz, 1 H, H-1GalN), 5.28 (s, 1 H, CHPh), 5.07 (d, J ¼ 4.2 Hz, 1 H,
J ¼ 3.0 Hz, 1 H, H-4GalN00 ), 3.70e3.50 (m, 8 H, H-2Rha, H-3Rha, H-
0
000
000
H-1GalN ), 4.84 (s, 1 H, H-1Rha), 4.72e4.63 (m, 2 H, H-2GalN, H-3GalN),
3GalN , H-5GalN, H-5GalN , H-5Rha, H-6aGalN , -OCH2CH2-), 3.37 (d,
0 0
0
4.56 (dt, J ¼ 10.2, 3.6 Hz, 1 H, H-2GalN ), 4.37 (d, J ¼ 12.0 Hz, 1 H, H-
6aGalN), 4.34 (d, J ¼ 3.0 Hz, 1 H, H-4GalN), 4.14 (d, J ¼ 12.0 Hz, 1 H, H-
6bGalN), 4.03 (t, J ¼ 6.0 Hz, 1 H, H-3Rha), 4.00e3.95 (m, 1 H,
-OCH2CH2-), 3.92 (d, J ¼ 6.0 Hz, 1 H, H-2Rha), 3.87 (d, J ¼ 3.0 Hz, 1 H,
J ¼ 11.4 Hz, 1 H, H-6bGalN ), 3.34 (dd, J ¼ 10.8, 3.0 Hz, 1 H, H-3GalN ),
000
3.27 (d, J ¼ 12.0 Hz, 1 H, H-6bGalN ), 3.23 (dd, J ¼ 10.8, 7.2 Hz, 1 H, H-
000
4Rha), 3.23e3.14 (m, 2 H, -CH2CH2N3), 3.00 (s, 1 H, H-5GalN ), 2.92 (s,
0
1 H, H-5GalN ), 1.83e1.67 (m, 2 H, -OCH2CH2CH2N3), 1.61 (s, 3 H,
0
0
H-4GalN ), 3.76 (d, J ¼ 11.4 Hz, 1 H, H-6aGalN ), 3.74e3.69 (m, 1 H, H-
5Rha), 3.61 (s,1 H, H-5GalN), 3.59e3.54 (m,1 H, -OCH2CH2-), 3.44 (dd,
-NHCOCH3), 1.35 [s, 3 H, -C(CH3)2], 1.33 (s, 3 H, -NHCOCH3), 1.12 (d,
0
J ¼ 6.6 Hz, 3 H, H-6Rha), 0.94 (d, J ¼ 6.0 Hz, 3 H, H-6Rha ), 0.81 [s, 3 H,
0
0
J ¼ 10.2, 3.0 Hz, 1 H, H-3GalN ), 3.37 (d, J ¼ 11.4 Hz, 1 H, H-6bGalN ),
-C(CH3)2]; 13C NMR (150 MHz, CDCl3):
d
170.5 (C¼O), 169.9 (C¼O),
3.28 (q, J ¼ 6.0 Hz, 1 H, H-4Rha), 3.25e3.15 (m, 2 H, -CH2CH2N3), 2.97
168.3 (C¼O), 168.2 (C¼O), 167.84 (C¼O), 167.77 (C¼O), 166.7 (C¼O),
165.3 (C¼O), 164.8, (C¼O) 137.4, 137.3, 137.1, 134.8, 134.7, 134.1,
133.5, 133.1, 132.1, 1313, 131.2, 131.1, 129.8, 129.64, 129.60, 129.5,
129.21, 129.18, 129.1, 128.9, 128.6, 128.54, 128.49, 128.3, 128.2, 128.1,
126.5, 126.2, 126.1, 124.1, 124.0, 123.1, 122.5, 108.8 [-C(CH3)2], 101.6
(CHPh), 101.5 (CHPh), 101.1 (CHPh), 101.0 (CHPh), 99.7 (C-1Rha), 99.6
0
(s, 1 H, H-5GalN ), 2.39 (d, J ¼ 6.0 Hz, 1 H, -OH), 1.84e1.76 (m, 1 H,
-OCH2CH2CH2N3), 1.75e1.66 (m, 1 H, -OCH2CH2CH2N3), 1.46 [s, 3 H,
-C(CH3)2], 1.42 (s, 3 H, -NHCOCH3), 1.26 [s, 3 H, -C(CH3)2], 1.08 (d,
J ¼ 6.0 Hz, 3 H, H-6Rha); 13C NMR (150 MHz, CDCl3):
d
170.1 (C¼O),
168.3 (C¼O), 167.8 (C¼O), 137.3, 137.1, 134.8, 134.7, 131.3, 131.2,
129.6, 129.1, 128.6, 128.2, 126.5, 126.1, 124.1, 123.1, 109.2 [-C(CH3)2],
101.6 (CHPh), 101.0 (CHPh), 100.0 (C-1Rha), 98.2 (C-1GalN), 95.3 (C-
00
0
000
(C-1GalN ), 98.6 (C-1Rha ), 98.2 (C-1GalN), 96.3 (C-1GalN ), 95.0 (C-
0
000
0
1GalN ), 82.9 (C-4Rha), 77.8 0(C-3GalN ), 77.1 (C-3Rha), 76.3 0(C-3GalN ),
0
0
0
000
1GalN ), 77.5 (C-3Rha), 76.9 (C-3GalN ), 75.3 (C-2Rha), 74.9 (C-4GalN ),
75.8 (C-2Rha), 75.1 (C-4GalN ), 74.5 (C-4GalN ), 72.8 (C-4Rha ), 71.9 (C-
00
00
0
73.4 (C-4Rha), 71.34 (C-3GalN), 71.32 (C-4GalN), 69.4 (C-6GalN), 68.5 (C-
3GalN ), 71.60 (C-4GalN ), 71.2 (C-4GalN), 71.1 (C-3GalN), 70.5 (C-2Rha ),
0
0
0
0
0
0
6GalN0), 67.5 (C-5Rha), 66.4 (C-5GalN), 66.1 (-OCH2CH2-), 63.39 (C-
69.7 (C-3Rha ), 69.40 (C-6GalN ), 69.36 (C-6GalN), 68.6 (C-6GalN ), 68.5
0 0
0
5GalN ), 52.1 (C-2GalN), 48.1 (-CH2CH2N3), 47.3 (C-2GalN ), 28.8
(C-6GalN ), 66.5 (C-5Rha ), 66.4 (C-5GalN), 66.1 (-OCH2CH2-), 66.0 (C-
00 0 000 00
(-OCH2CH2CH2N3), 27.7 [-C(CH3)2], 25.8 [-C(CH3)2], 22.7
5GalN ), 64.7 (C-5Rha), 63.4 (C-5GalN ), 63.0 (C-5GalN ), 52.5 (C-2GalN000),
0
(-NHCOCH3), 18.1 (C-6Rha); ESI-TOF HRMS m/z: Calcd for
52.1 (C-2GalN), 48.0 (-CH2CH2N3), 47.2 (C-2GalN ), 47.0 (C-2GalN ),
C
C
48H55N5O16Na [MþNa]þ 980.3536; Found 980.3547; Calcd for
48H55N5O16K [MþK]þ 996.3275; Found 996.3286.
40.5 (-OCOCH2Cl), 28.8 (-OCH2CH2CH2N3), 27.7 [-C(CH3)2], 25.7
[-C(CH3)2], 22.8 (-NHCOCH3), 22.6 (-NHCOCH3), 17.7 (C-6Rha), 17.4
0
(C-6Rha ); ESI-TOF HRMS m/z: Calcd for C106H109ClN7O34 [MþH]þ
4.18. 3-Azidopropyl 2,3-di-O-benzoyl-4-O-chloroacetyl-
rhamnopyranosyl-(1 / 3)- 2-acetamido-4,6-O-benzylidene-2-
deoxy- -D-galactopyranosyl-(1 / 3)-4,6-O-benzylidene-2-deoxy-
2-phthalimido- -D-galactopyranosyl-(1 / 4)-2,3-isopropylidene-
-L-rhamnopyranosyl-(1 / 3)-2-acetamido-4,6-O-benzylidene-2-
a-L-
2058.6698; Found 2058.6721.
a
4.19. 3-Azidopropyl
2-deoxy- -D-galactopyranosyl-(1 / 3)-2-acetamido-2-deoxy-
galactopyranosyl-(1 / 4)- -L-rhamnopyranosyl-(1 / 3)-2-
acetamido-2-deoxy- -D-galactopyranosyl-(1 / 3)-2-acetamido-2-
deoxy- -D-galactopyranoside (2)
a-L-rhamnopyranosyl-(1 / 3)-2-acetamido-
b
a
b
-D-
a
a
deoxy-
a
-D-galactopyranosyl-(1 / 3)-4,6-O-benzylidene-2-deoxy-
a
2-phthalimido-
b
-D-galactopyranoside (22)
b
After a mixed solution of 3 (20 mg, 0.016 mmol), 21 (13 mg,
0.013 mmol), and activated MS 4 Å (200 mg) in anhydrous CH2Cl2
(3 mL) was stirred at rt for 2 h under a N2 atmosphere, it was cooled
After a solution of 22 (15 mg, 7.3 mmol) in ethanol (4 mL) and
80% hydrazine hydrate (1 mL) was refluxed for 6 h, the solvent was
then concentrated and the resulting residue was purified by size
to ꢀ40 ꢁC, and NIS (5 mg, 0.02 mmol) and AgOTf (2 mg, 7.7
mmol)
exclusion chromatography on a Bio-Gel LH-20 column with
were then added. The reaction mixture was stirred ꢀ40 ꢁC for
30 min and slowly warmed to 0 ꢁC and stirred for another 1 h, and
then neutralized with Et3N. The resulting mixture was diluted with
CH2Cl2 (20 mL), filtered through a pad of Celite, and the filtrate was
washed successively with saturated aq. Na2S2O3 (20 mL) and brine
methanol as the eluent to get a white solid. The product was dis-
solved in pyridine (6 mL) containing acetic anhydride (2 mL). The
reaction mixture was stirred at rt for 8 h and then concentrated to
give a pale yellow solid, which was then dissolved in 80% HOAc
(6 mL) and stirred at 70 ꢁC for overnight. The reaction mixture was

N. Bi et al. / Carbohydrate Research 451 (2017) 1e11
11
[4] J.W. Costerton, R.T. Irvin, K.J. Cheng, Annu. Rev. Microbiol. 35 (1981) 299e324.
[5] J.M. Tarbell, L.M. Cancel, J. Intern. Med. 280 (2016) 97e113.
[6] E.R. Moxon, J.S. Kroll, Curr. Top. Microbiol. Immunol. 150 (1990) 65e85.
[7] R.F. Maldonado, I. Sa-Correia, M.A. Valvano, FEMS Microbiol. Rev. 40 (2016)
480e493.
[8] A. Weintraub, Carbohydr. Res. 338 (2003) 2539e2547.
[9] C. Alexander, E.T. Rietschel, J. Endotoxin Res. 7 (2001) 167e202.
[10] S.A. Plotkin, Nat. Med. 11 (2005) S5eS11.
[11] A. Zariri, P. van der Ley, Expert Rev. Vaccines 14 (2015) 861e876.
[12] S. Zielen, J. Trischler, R. Schubert, Expert Rev. Clin. Immunol. 11 (2015)
409e418.
[13] P. Vandamme, P. Dawyndt, Syst. Appl. Microbiol. 34 (2011) 87e95.
[14] T. Coenye, P. Vandamme, J.R. Govan, J.J. LiPuma, J. Clin. Microbiol. 39 (2001)
3427e3436.
[15] A. Isles, I. Maclusky, M. Corey, R. Gold, C. Prober, P. Fleming, H. Levison,
J. Pediatr. 104 (1984) 206e210.
[16] J.J. Lipuma, Curr. Opin. Pulm. Med. 11 (2005) 528e533.
[17] E. Mahenthiralingam, A. Baldwin, P. Vandamme, J. Med. Microbiol. 51 (2002)
533e538.
[18] R. Reik, T. Spilker, J.J. Lipuma, J. Clin. Microbiol. 43 (2005) 2926e2928.
[19] T. Coenye, T. Spilker, A. Martin, J.J. LiPuma, J. Clin. Microbiol. 40 (2002)
3300e3307.
then co-evaporated with toluene (2 ꢂ 5 mL), and the resulting
product was then dissolved MeOH (4 mL) followed by addition of
NaOMe (0.5 M) in MeOH until the pH value reached 10. The mixture
was stirred at rt for overnight, and then neutralized with Amberlite
IR 120 (Hþ). The solution was filtered, and the filtrate was
concentrated. The resulting residue was purified by size exclusion
chromatography on a Sephadex G-10 column with distilled water
as the eluent and then lyophilized to give 2 (5.6 mg, 64%) as a white
25
solid. [
a]
þ105 (c 0.1, H2O); 1H NMR (600 MHz, D2O):
d 4.91 (d,
D
J ¼ 3.0 Hz, 2 H, 2 ꢂ H-1GalN), 4.68 (s, 2 H, 2 ꢂ H-1Rha), 4.61 (d,
J ¼ 9.6 Hz, 1 H, H-1GalN), 4.35 (d, J ¼ 8.4 Hz, 1 H, H-1GalN), 4.20 (dd,
J ¼ 10.8, 3.0 Hz, 2 H, 2 ꢂ H-2GalN), 3.97 (br d, J ¼ 6.6 Hz, 2 H),
3.90e3.79 (m, 5 H), 3.75e3.40 (m, 24 H), 3.26 (t, J ¼ 9.6 Hz, 1 H),
3.22 (t, J ¼ 6.6 Hz, 2 H, -CH2CH2N3), 1.90, 1.85 (2 s, 4 ꢂ 3 H, 4 ꢂ -
NHCOCH3), 1.73e1.64 (m, 2 H, -OCH2CH2CH2N3), 1.16 (d, J ¼ 6.0 Hz,
3 H, H-6Rha), 1.09 (d, J ¼ 6.0 Hz, 3 H, H-6Rha); 13C NMR (150 MHz,
D2O):
d 174.5, 174.4, 174.31, 174.30, 102.2, 101.9, 101.5, 101.0, 93.2,
[20] S. Kotrange, B. Kopp, A. Akhter, D. Abdelaziz, A. Abu Khweek, K. Caution,
B. Abdulrahman, M.D. Wewers, K. McCoy, C. Marsh, S.A. Loutet, X. Ortega,
M.A. Valvano, A.O. Amer, J. Leukoc. Biol. 89 (2011) 481e488.
[21] M.S. Saldias, X. Ortega, M.A. Valvano, J. Med. Microbiol. 58 (2009) 1542e1548.
[22] X. Ortega, T.A. Hunt, S. Loutet, A.D. Vinion-Dubiel, A. Datta, B. Choudhury,
J.B. Goldberg, R. Carlson, M.A. Valvano, J. Bacteriol. 187 (2005) 1324e1333.
[23] X. Zhang, G. Gu, Z. Guo, Eur. J. Org. Chem. (2015) 7075e7085.
[24] X. Geng, L. Wang, G. Gu, Z. Guo, Carbohydr. Res. 427 (2016) 13e20.
[25] D. Wang, W. Zhuge, Z. Guo, G. Gu, Carbohydr. Res. 442 (2017) 41e51.
[26] S.S. Mandal, G. Liao, Z. Guo, RSC Adv. 5 (2015) 23311e23319.
[27] G. Grundler, R.R. Schmidt, Liebigs Ann. Chem. 1984 (1984) 1826e1847.
[28] K. Kakita, T. Tsuda, N. Suzuki, S. Nakamura, H. Nambu, S. Hashimoto, Tetra-
hedron 68 (2012) 5005e5017.
[29] H. Tanaka, R. Takeuchi, M. Jimbo, N. Kuniya, T. Takahashi, Chem. Eur. J. 19
(2013) 3177e3187.
[30] G. Gu, M. Fang, Y. Du, Carbohydr. Res. 346 (2011) 2801e2804.
[31] R.R. Schmidt, J. Michel, Angew. Chem. Int. Ed. 19 (1980) 731e732.
[32] M. Numata, M. Sugimoto, K. Koike, T. Ogawa, Carbohydr. Res. 163 (1987)
209e225.
93.1, 79.8, 76.0 (2C), 74.9, 74.7, 74.4, 74.2, 71.8, 71.40, 71.39, 70.4,
70.2, 70.1, 69.8, 69.1, 68.1, 68.0, 67.5, 67.0, 63.1 (2C), 60.9, 60.8, 60.7
(2C), 51.0, 50.6, 48.1 (2C), 47.7, 28.0, 22.2, 22.1, 21.8 (2C), 16.9, 16.5;
ESI-TOF HRMS m/z: Calcd for C47H80N7O29 [MþH]þ 1206.4995;
Found 1206.5015; Calcd for C47H79N7O29Na [MþNa]þ 1228.4814;
Found 1228.4809.
Acknowledgment
This research was supported by grants from the Shandong
Provincial Natural Science Foundation (No. ZR2015BM020) and the
Science and Technology Development Project of Shandong Prov-
ince (No. 2015GSF118019 and 2016GGH4502).
Appendix A. Supplementary data
[33] F. Belot, J.-C. Jacquinet, Carbohydr. Res. 290 (1996) 79e86.
[34] H.M. Christensen, S. Oscarson, H.H. Jensen, Carbohydr. Res. 408 (2015) 51e95.
[35] R.R. Schmidt, A. Toepfer, Tetrahedron Lett. 32 (1991) 3353e3356.
[36] A.V. Demchenko, E. Rousson, G.J. Boons, Tetrahedron Lett. 40 (1999)
6523e6526.
Supplementary data including 1H NMR, 13C NMR, and ESI-HRMS
spectra of all final products and intermediates are available at
http://dx.doi.org/10.1016/j.carres.2017.09.001.
[37] C.E. Martin, F. Broecker, S. Eller, M.A. Oberli, C. Anish, C.L. Pereira,
P.H. Seeberger, Chem. Commun. 49 (2013) 7159e7161.
[38] K. Bock, C. Pedersen, J. Chem. Soc. Perk. Trans. 2 (1974) 293e299.
[39] A. Maranduba, A. Veyrieres, Carbohydr. Res. 151 (1986) 105e119.
[40] M. Bertolini, C.P.J. Glaudemans, Carbohydr. Res. 15 (1970) 263e270.
[41] B. Mukhopadhyay, D.A. Russell, R.A. Field, Carbohydr. Res. 340 (2005)
1075e1080.
References
[1] C.R. Raetz, C. Whitfield, Annu. Rev. Biochem. 71 (2002) 635e700.
[2] K. Miyake, S. Iijima, Adv. Biochem. Eng. Biotechnol. 90 (2004) 89e111.
[3] K. Bazaka, R.J. Crawford, E.L. Nazarenko, E.P. Ivanova, Adv. Exp. Med. Biol. 715
(2011) 213e226.