Synthesis of β-(1→6)-linked glucosamine oligosaccharides corresponding to fragments of the bacterial surface polysaccharide poly-N-acetylglucosamine

Article abstract of DOI:10.1016/j.carres.2006.08.010

A series of 3-β-acetamidopropyl oligo-β-(1→6)-glucosamines consisting of 5, 7, 9 and 11 glucosamine residues, and a series of corresponding per-N-acetylated derivatives were synthesized using a convergent blockwise approach. These compounds represent frag

Full text of DOI:10.1016/j.carres.2006.08.010

Carbohydrate Research 342 (2007) 567–575
Synthesis of b-(1!6)-linked glucosamine
oligosaccharides corresponding to fragments of the bacterial
surface polysaccharide poly-N-acetylglucosamine
Marina L. Gening,a Yury E. Tsvetkov,a Gerald B. Pierb and Nikolay E. Nifantieva,*
aN.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky prosp. 47, 119991 Moscow, Russia
bChanning Laboratory, Brigham and Women’s Hospital, Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA
Received 23 June 2006; received in revised form 7 July 2006; accepted 9 August 2006
Available online 6 September 2006
Dedicated to the memory of Professor Nikolay K. Kochetkov
Abstract—A series of 3-b-acetamidopropyl oligo-b-(1!6)-glucosamines consisting of 5, 7, 9 and 11 glucosamine residues, and a
series of corresponding per-N-acetylated derivatives were synthesized using a convergent blockwise approach. These compounds
represent fragments of a bacterial surface polysaccharide produced by numerous bacterial pathogens, including Staphylococcus
aureus, and will be used as models for its biochemical and immunological properties.
ꢀ 2006 Elsevier Ltd. All rights reserved.
Keywords: Staphylococcus aureus; Poly-b-(1!6)-N-acetyl glucosamine; PNAG; Oligoglucosamines; Convergent synthesis
1. Introduction
its immunogenicity depends on the degree of N-acetyl-
ation.5 However, finding the optimal form for eliciting
high titers of protective antibody is a difficult task.
When PNAG is isolated from bacterial sources, a hetero-
geneous mixture of poly- and oligosaccharides with dif-
ferent immunological activities is obtained. Therefore,
synthetic oligoglucosamines with glucosamine units
bearing N-acetylated and free amino groups in defined
positions are needed to determine the structure of active
epitopes. As a first goal, we set out to synthesize oligo-
glucosamines, composed of glucosamine residues where-
in either all of the amino groups were unprotected or N-
acetylated.
To date, only a few papers dealing with the syntheses
of oligo-b-(1!6)-glucosamine derivatives, including
O-substituted oligomers,6 have been published. Different
approaches have been used such as solid-phase synthesis
(trisaccharide),6 multi-component coupling using solu-
tion and polymer support technology (trisaccharide),7
ring-opening polymerization using 1,6-anhydro deriva-
tives (trisaccharide),8 one-pot synthesis (tetrasaccha-
ride),9 and block synthesis (penta-,6 hexa-,10 and
nonasaccharide11). Some of these methods resulted in
In modern medicine many bacterial species are capable
of causing diseases in hospitalized patients, often due
to their ability to bind, to adhere, and to form biofilms
on indwelling medical devices. Among the most promi-
nent ones are the staphylococci, which cause a wide
range of diseases in animals and humans. Staphylococ-
cus aureus and coagulase-negative staphylococci, most
notably S. epidermidis, are important causes of infection
related to colonization of medical implants and forma-
tion of biofilms.1 The importance of biofilm production
for the virulence of S. aureus and S. epidermidis has been
shown by several clinical and animal studies.2 Numer-
ous components of these extracellular biofilm layers
have been identified, but one of the major components
is poly-b-(1!6)-N-acetyl glucosamine (PNAG).3,4 It
has also been shown that this antigen has a good poten-
tial for use as an effective immunotherapeutic agent, but
*
Corresponding author. Tel./fax: +7 495 135 8784; e-mail: nen@
ioc.ac.ru
0008-6215/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2006.08.010

568
M. L. Gening et al. / Carbohydrate Research 342 (2007) 567–575
acceptable yields of oligosaccharides, which were
mainly prepared as substituted, but not the de-blocked
derivatives that are needed for biochemical investiga-
tions. The synthesis of both forms of oligo-b-(1!6)-
glucosamines (N-unsubstituted and N-acetylated) in
relation to PNAG studies has not been published so far.
Our first approach to the synthesis of these structures
involved the reaction of terminated oligomerization,
which has previously proven to be effective for the
assembly of some other oligo- and polysaccharides.12,13
However, the results of our experiments revealed a
low efficiency of this method for the preparation of
oligo-b-(1!6)-glucosamines.14 Therefore, blockwise
assembling of oligosaccharide chains was thought to
potentially be a more reliable and scalable strategy
based on the known examples of the syntheses of
oligo-b-(1!6)-glucosamines and our experiments using
terminated oligomerization.
To determine the sufficient length of oligosaccharide
ligands for effective binding to antibodies to PNAG, a
representative series of oligoglucosamines with a differ-
ent number of glucosamine units were needed; therefore,
oligoglucosamines with 5, 7, 9, and 11 monosaccharide
residues, containing either unsubstituted (15–18) or
N-acetylated (19–22) amino groups, were selected as
the target structures. These compounds were prepared
from a series of selectively substituted precursors (8,
10, 12, 13) carrying Z-amidopropyl aglycon suitable
for further functionalization and glycoconjugate design,
which is the goal in the next step of our project.
and purification also enabled us to avoid silica gel chro-
matography in all further glycosylation steps.
For the synthesis of acceptor blocks bearing a pro-
tected 3-aminopropyl moiety at the reducing terminal
sugar, we started from compound 4 described in our
previous work.14 The reaction of 4 with disaccharide 2
furnished compound 6 in 94% yield. Selective removal
of the sole O-acetyl group by treatment with HCl–
MeOH resulted in almost quantitative yield of the trisac-
charide acceptor 7. The presence of a free hydroxyl
group at C-6 was confirmed by the shifts of the signal
for C-6 and C-5 of the terminal glucosamine residue in
the 13C NMR spectrum from d 62.40 (C-6III-OAc) to d
61.21 (C-6III-OH) and from d 71.74 (C-5III-OAc) to d
74.20 (C-5III-OH). Subsequent coupling between thio-
glycoside 2 and acceptor 7 produced one of the target
compounds, pentasaccharide 10, in 90% yield, which
was deacetylated in a similar way to give pentasaccha-
ride acceptor block 11. The signals for each type of re-
lated protons (carbon atoms) in the NMR spectra of
pentasaccharide 10 and all higher oligomers appeared
as complex multiplets, resulting from superposition of
signals of very close but not completely equivalent pro-
tons (carbon atoms) belonging to individual glucos-
amine residues. The length of the oligosaccharide chains
was revealed from the ratios between protons of the
spacer-arm moiety and protons at the C-3 atoms.
The reaction of tetrasaccharide donor 5 with acceptor
7 furnished the desired spacer-armed heptasaccharide 8
in 74% yield. Selective deacetylation of 8 clearly pro-
duced 9, but longer reaction times were required (2 days
compared to 16 h for 6). Purification of heptasaccharide
8 and longer oligosaccharides was performed using a
Bio-Beads SX-1 gel with an exclusion limit of 14,000.
Similarly, the target nonasaccharide 13 was obtained
in 60% yield by the reaction of thioglycoside 5 with pen-
tasaccharide acceptor 11. Glycosylation of heptasaccha-
ride acceptor 9 with donor 5 was carried out under the
same conditions as previous glycosylation reactions
but resulted in only 50% yield of the undecasaccharide
12, with 40% of the unreacted 9 recovered. Tetrasaccha-
ride glycal 14 [d 6.75 (s, 1H, H-1), d 5.85 (d, 1H, J 3.7,
H-3), d 105.33 (C-1)] was also isolated as a main side
product (Fig. 1). Attempts at reducing the formation
of 14 by the use of non-basic molecular sieves AW-300
failed and gave rise to the formation of remarkably
low yield of product 12. The relatively low reactivity
of acceptor 9 can be probably explained by its bulky
structure.
2. Results and discussion
Although attempts to prepare oligoglucosamines by ter-
minated oligomerization failed,14 many synthetic instru-
ments elaborated within this work were widely used in
the block synthesis presented below. These included
protecting group strategies (acetyl and benzoyl as
temporary and permanent O-protecting groups, and
phthaloyl and benzyloxycarbonyl for protection of glu-
cosamine and spacer-arm amino groups, respectively),
mono- and disaccharide building blocks 1–4 (Scheme
1), and optimal glycosylation conditions.
For the synthesis of target oligosaccharides, we
employed a convergent approach based on the use of a
minimal number of relatively large building blocks.
The tetrasaccharide thioglycoside 5 was proposed as a
key glycosylating agent. It was prepared in 76% yield
by glycosylation of thioglycoside 3 with bromide 1
(Scheme 1) under Helferich conditions. Since the result-
ing tetrasaccharide 5 differed sufficiently in the molecular
mass from the starting materials, it could be readily iso-
lated by means of gel-permeation chromatography on
the hydrophobic gel Bio-Beads SX-3 (exclusion limit
2000). This simple and convenient method of isolation
As the next step in the preparation of target
compounds 15–22, Z-groups in the protected precursors
8, 10, 12, and 13 were replaced by an acetyl (Scheme 2)
followed by total N,O-deprotection of glucosamine
residues by treatment with hydrazine hydrate in boiling
EtOH. Free oligosaccharides 15–18 formed in the yields
of ꢀ85% were purified by gel-permeation chromatography.

M. L. Gening et al. / Carbohydrate Research 342 (2007) 567–575
569
AcO
RO
HO
BzO
BzO
O
O
BzO
BzO
BzO
BzO
O
O
O
O
NHZ
O
O
PhthN
PhthN
BzO
BzO
BzO
BzO
Br
SEt
PhthN
PhthN
PhthN
1
4
2 R = Ac
3 R = H
a
b + 3
c + 2
RO
O
AcO
BzO
BzO
O
O
BzO
BzO
O
O
PhthN
BzO
BzO
O
O
PhthN
BzO
BzO
O
O
PhthN
BzO
BzO
NHZ
O
O
PhthN
BzO
BzO
O
PhthN
O
6 R = Ac
7 R = H
PhthN
a
BzO
BzO
SEt
5
PhthN
c + 2
c + 7
RO
BzO
O
O
BzO
O
PhthN
PhthN
BzO
BzO
RO
BzO
O
BzO
O
O
O
NHZ
O
3
BzO
BzO
O
PhthN
BzO
BzO
PhthN
O
O
PhthN
PhthN
BzO
BzO
10 R = Ac
11 R = H
NHZ
O
5
a
8 R = Ac
9 R = H
a
c + 5
AcO
BzO
O
c + 5
O
BzO
BzO
AcO
BzO
O
PhthN
PhthN
O
O
BzO
BzO
BzO
O
BzO
O
O
NHZ
PhthN
O
7
BzO
BzO
O
BzO
BzO
PhthN
O
PhthN
NHZ
O
9
13
PhthN
12
Scheme 1. Synthesis of protected oligoglucosamines. Reagents and conditions: (a) AcCl, MeOH; (b) HgBr2, Hg(CN)2, CH3CN; (c) NIS, TfOH, MS
˚
4 A, CH2Cl2.
1H NMR spectra of compounds 15–18 represent a num-
ber of broad multiplets (vide supra), from which only
signals of the aglycon moiety [d 1.81 (m,
AcO
OCH2CH2CH2N), 1.90 (s, N–COCH3), 3.20; 3.30 (2m,
OCH2CH2CH2N)] and some signals of glucosamines [d
2.90 (m, H-2), 4.23 (m, H-6 of glycosylated residues),
and 4.70 (m, H-1)] can be assigned unambiguously.
The length of the oligosaccharide chain was confirmed
by the ratio of integral intensities of spacer protons
and protons at C-2 and the data of ESI mass-spectra.
To obtain the fully N-acetylated compound, pentasac-
charide 15 was treated with an excess of acetic anhydride
O
BzO
BzO
O
O
PhthN
BzO
BzO
O
O
PhthN
BzO
BzO
O
O
PhthN
BzO
BzO
14
PhthN
Figure 1.

570
M. L. Gening et al. / Carbohydrate Research 342 (2007) 567–575
In conclusion, a series of oligo-b-(1!6)-glucosamines
AcO
BzO
O
comprising 5, 7, 9, and 11 monosaccharide residues with
either all free or all N-acetylated amino groups have
been efficiently prepared. Biochemical and immunologi-
cal investigations of the properties of these synthetic
oligoglucosamines, as well as their theoretical (MM3 cal-
O
BzO
O
PhthN
BzO
BzO
O
O
PhthN
BzO
BzO
NHZ
O
n
PhthN
3
culations) and experimental (NOE-NMR, JC,H-NMR)
conformational analysis, are in progress.
10 n = 3
8 n = 5
13 n = 7
12 n = 9
a
3. Experimental
HO
HO
3.1. General methods
O
O
HO
HO
O
H2N
NMR spectra were recorded on Bruker DRX-500 and
Bruker AM-300 instruments. The spectra of protected
oligosaccharides were measured for solutions in CDCl3,
and 1H NMR chemical shifts were referenced to a resid-
ual solvent signal. NMR spectra of free oligosaccharides
were measured for solutions in D2O. Optical rotation
values were measured on a JASCO DIP-360 polarimeter
at 22 2 ꢁC. TLC was performed on Silica Gel 60 F254
plates (E. Merck), and visualization was accomplished
using UV light or by charring with 10% H3PO4 in etha-
nol. Column chromatography was carried out on Silica
gel 60 (40–63 lm, E. Merck). Gel-permeation chroma-
tography of protected oligosaccharides was performed
on columns with Bio-Beads SX-3 (15 · 500 mm) or
Bio-Beads SX-1 (20 · 600 mm) (Bio-Rad Laboratories).
Gel-permeation chromatography of free oligosaccha-
rides was performed on a column with TSK HW-40
(S) (25 · 400 mm) in 0.1 M AcOH. ESIMS spectra were
recorded with a Micromass Quattro system. All reac-
tions involving air- or moisture-sensitive reagents were
carried out using dry solvents under dry argon.
O
HO
O
H2N
HO
HO
NHAc
O
H2N
n
15 n = 3
16 n = 5
17 n = 7
18 n = 9
b
HO
HO
O
O
HO
HO
O
AcNH
O
HO
O
AcNH
HO
HO
NHAc
O
n
AcNH
19 n = 3
20 n = 5
21 n = 7
22 n = 9
Scheme 2. Reagents and conditions: (a) H2, Pd(OH)2, MeOH–THF;
Ac2O, Py; N2H4ÆH2O, EtOH; (b) Ac2O, MeOH–H2O.
in aqueous methanol. Product 19 was isolated in almost
quantitative yield. The completeness of N-acetylation
was deduced from the absence of the signal at d ꢀ2.90
characteristic for H-2 of the glucosamine residue with
a free amino group and the upfield shift for the signal
for H-1 from d 4.70 (free amines) to d 4.50 (NH–Ac).
When applied to heptasaccharide 16, these conditions
did not result in complete N-acetylation; repeated treat-
ment in the presence of solid NaHCO3 was necessary to
complete the reaction. Oligo-N-acetyl glucosamines 21
and 22 were prepared in a similar way. It should be
noted that all N-acetylated oligosaccharides were
completely soluble in water at 0.5 mg/mL concentration
except undecasaccharide 22, which was remarkably less
water-soluble and gave an opalescent solution with the
partial formation of a sediment. The lower solubility
of undecasaccharide 22 could potentially be accounted
for by the appearance of helical conformational regular-
ity in its chain or by its ability to self-aggregate into
macro-complexes through inter-molecular interactions
of acetamido-groups.
3.2. General procedure for Helferich glycosylation
To a solution of a glycosyl acceptor (1 mmol), Hg(CN)2
(1.2 mmol), and HgBr2 (0.36 mmol) in anhyd CH3CN
(1 mL) was added a solution of glycosyl bromide
(1.2 mmol) in anhyd CH3CN (0.5 mL) at rt under dry
argon. The mixture was stirred for 30 min, then diluted
with CHCl3 and poured into a mixture of 1 M aq KI
and NaHCO3, then extracted with CHCl3. The organic
extract was dried over anhyd Na2SO4 and concentrated.
The residue was subjected to chromatography on a Bio-
Beads SX-3 column in toluene to give the desired product.
3.3. General procedure for selective deacetylation in the
presence of benzoyl groups
A solution of a 6-O-acetyl derivative (1 mmol) in
CH2Cl2 (6 mL) was diluted with abs MeOH (20 mL)
and then AcCl (0.2 mL) was added under cooling with
an ice-bath. The mixture was kept for 16 h at rt and then

M. L. Gening et al. / Carbohydrate Research 342 (2007) 567–575
571
concentrated. The residue was purified by flash chroma-
tography on silica gel (EtOAc–toluene) to give the prod-
uct with a free terminal 6-OH group.
0.29 mmol) in 0.1 mL of CH2Cl2 was added. The mix-
ture was kept in the dark for 1 h at rt and then evapo-
rated to give bromide 1. Glycosyl bromide 1 (300 mg,
0.26 mmol) was reacted with 3 (210 mg, 0.20 mmol) as
described in Section 3.2 to give 5 (315 mg, 76%) as a col-
orless foam: [a]D +13 (c 1, CHCl3); 1H NMR (CDCl3): d
1.15 (t, 3H, J 7.8, SCH2CH3), 1.95 (s, 3H, COCH3), 2.5–
2.8 (m, 2H, SCH2CH3), 3.58 (m, 1H, H-6), 3.75 (m, 3H,
H-5, 2H-6), 3.87 (m, 1H, H-6), 3.95–4.10 (m, 4H, 2H-5,
2H-6), 4.15–4.35 (m, 4H, H-2, H-5, 2H-6), 4.45–4.6 (m,
3H, 3H-2), 5.05 (t, 1H, J 9.7, H-4), 5.20 (t, 1H, J 9.5, H-
4), 5.35–5.50 (m, 3H, 2H-1, H-4), 5.55 (m, 2H, H-1, H-
4), 5.69 (d, 1H, J 8.4, H-1IV), 6.10 (m, 2H, 2H-3), 6.22 (t,
1H, J 9.7, H-3), 6.32 (t, 1H, J 9.7, H-3IV), 7.15–7.55 (m,
24H, aromatics), 7.60–7.90 (m, 32H, aromatics); 13C
NMR: d 14.92, 20.60 (COCH3), 23.76, 53.84 (4C-2),
54.61, 54.78, 62.55, 67.18, 67.82, 69.92, 70.14, 70.52,
70.90, 71.08, 71.73, 72.05, 72.67, 73.11, 77.36, 80.70
(C-1I), 97.07 (1C, C-1), 97.98 (2C, C-1), 123.52,
123.69, 125.28, 128.18, 128.37, 128.68, 128.90, 129.01,
129.29, 129.74, 129.79, 131.19, 131.63, 133.10, 133.29,
133.86, 134.00, 134.28, 164.82, 164.97, 165.17, 165.23,
165.43, 165.57, 167.10, 167.84, 170.61. Anal. Calcd for
3.4. General procedure for NIS–TfOH-catalyzed
glycosylation
A solution of an ethyl thioglycoside (0.1 mmol) and a
glycosyl acceptor (0.09 mmol) in freshly distilled anhy-
˚
drous CH2Cl2 (1 mL) containing 4 A MS (130 mg) was
stirred at rt under argon for 1 h and then cooled to
ꢁ20 ꢁC. NIS (0.2 mmol) and TfOH (0.04 mmol) were
successively added and the resulting mixture was stirred
for an additional 30 min at ꢁ20 ꢁC. The reaction was
quenched with a drop of pyridine, allowed to attain rt,
diluted with CH2Cl2, and filtered through Celite. The fil-
trate was washed with 1 M Na2S2O3, then with water,
and dried with Na2SO4, and concentrated. The residue
was purified by chromatography on the Bio-Beads
SX-1 column in toluene.
3.5. General procedure for total deprotection of oligo-
glucosamines and subsequent N-acetylation
C
116H92N4O33S: C, 66.28; H, 4.41; N, 2.67. Found: C,
A protected oligosaccharide (0.01 mmol) was dissolved
in 1:1 MeOH–THF (1.5 mL) and Pd(OH)2/C (50 mg)
was added. The resulting mixture was stirred under an
H2 atmosphere (1 atm) overnight, then filtered through
Celite and the filtrate was concentrated. The product
of hydrogenolysis was dissolved in pyridine (0.5 mL)
and treated with Ac2O (0.2 mL) and the resultant mix-
ture was kept for 1 h at rt and concentrated. The residue
was dissolved in EtOH (10 mL) and N2H4ÆH2O (1 mL)
was added. The mixture was heated under reflux for
3 h, then concentrated and co-concentrated several
times with toluene under diminished pressure. The resi-
due was purified on a TSK HW-40S column in 0.1 M
AcOH to give a pure oligo-b-(1!6)-glucosamine. The
latter was N-acetylated by treatment with Ac2O
(50 lL) in 50% aqueous MeOH for 16 h at rt. The reac-
tion mixture was neutralized with solid NaHCO3 and an
additional portion of Ac2O (50 lL) was added. After 1 h
the solvent was evaporated and the crude product was
subjected to gel chromatography on TSK HW-40S in
0.1 M AcOH to provide an oligo-b-(1!6)-N-acetylglu-
cosamine oligosaccharide.
65.99; H, 4.30; N, 2.64.
3.7. 3-(Benzyloxycarbonylamino)propyl 6-O-acetyl-3,4-
di-O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyranosyl-
(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-D-
glucopyranosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-
phthalimido-b-D-glucopyranoside (6)
Glycosyl donor 2 (200 mg, 0.18 mmol) was reacted with
acceptor 4 (120 mg, 0.17 mmol) as described in Section
3.4 to give 6 (280 mg, 94%) as a colorless foam: [a]D
1
+14.6 (c 1, CHCl3); H NMR (CDCl3): d 1.60 (m, 2H,
OCH2CH2CH2N), 2.00 (s, 3H, COCH3), 3.05 (m, 2H,
OCH2CH2CH2N), 3.45 (m, 1H, OCH2CH2CH2N),
3.65–3.80 (m, 3H, OCH2CH2CH2N, 2H-6), 3.85 (m,
1H, H-5), 3.90 (m, 3H, H-5, 2H-6), 4.08 (m, 1H, H-
5III), 4.2 (d, 1H, J 12.1, H-6C), 4.27 (dd, 1H, J 5.3, H-
6III), 4.40 (m, 2H, 2H-2), 4.50 (dd, 1H, J 10.0 and 8.5,
H-2III), 5.00 (s, 2H, CH2Ph), 5.10 (m, 1H, NH), 5.21
(t, 1H, J 9.7, H-4), 5.30 (t, 1H, J 9.7, H-4), 5.38 (d,
1H, J 8.3, H-1), 5.45 (d, 1H, J 8.4, H-1), 5.53 (t, 1H, J
10.0, H-4III), 5.62 (d, 1H, J 8.5, H-1III), 6.10 (m, 2H,
2H-3), 6.23 (t, 1H, J 10.0, H-3III), 7.10–7.50 (m, 27H,
aromatics), 7.60–7.90 (m, 20H, aromatics); 13C NMR:
d 20.58 (COCH3), 29.44 (OCH2CH2CH2N), 37.96
(OCH2CH2CH2N), 54.69 (3C-2), 62.53 (C-6C), 66.27
(CH2Ph), 67.13 (OCH2CH2CH2N), 67.44 (C-6), 67.71
(C-6), 69.91 (C-4III), 70.17 (C-4), 70.24 (C-4), 70.92
(C-3), 71.05 (C-3III), 71.20 (C-3), 71.86 (C-5III), 73.23
(C-5), 73.30 (C-5), 97.49 (C-1), 97.95 (2C-1), 123.48,
125.24, 127.86, 127.93, 128.66, 128.97, 131.36, 131.54,
133.06, 133.25, 133.95, 134.07, 156.35 (OC(O)NH),
3.6. Ethyl 6-O-acetyl-3,4-di-O-benzoyl-2-deoxy-2-phthal-
imido-b-D-glucopyranosyl-(1!6)-3,4-di-O-benzoyl-2-
deoxy-2-phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-
O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyranosyl-
(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-1-thio-b-
D-glucopyranoside (5)
Compound 214 (300 mg, 0.27 mmol) was dissolved in
2 mL of anhyd CH2Cl2 and a solution of Br2 (15 lL,

572
M. L. Gening et al. / Carbohydrate Research 342 (2007) 567–575
164.96, 165.17, 165.55, 167.41, 170.553, 185.02. Anal.
Calcd for C97H80N4O28: C, 66.59; H, 4.61; N, 3.20.
Found: C, 66.40; H, 4.63; N, 3.22.
13C NMR (CDCl3): d 62.56 (C-6VII), 71.74 (C-5VII),
97.25, 97.51, 97.82, 97.95 (C-1). Anal. Calcd for
C
209H164N8O60: C, 66.98; H, 4.41; N, 2.99. Found: C,
66.77; H, 4.29; N, 2.97.
3.8. 3-(Benzyloxycarbonylamino)propyl 3,4-di-O-benz-
oyl-2-deoxy-2-phthalimido-b-D-glucopyranosyl-(1!6)-
3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyr-
anosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-
D-glucopyranoside (7)
3.10. 3-(Benzyloxycarbonylamino)propyl 3,4-di-O-ben-
zoyl-2-deoxy-2-phthalimido-b-D-glucopyranosyl-(1!6)-
3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyr-
anosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-
D-glucopyranosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-
phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-O-benzoyl-
2-deoxy-2-phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-
O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyranosyl-
(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-D-
glucopyranoside (9)
Compound 6 (280 mg, 0.16 mmol) was deacetylated as
described in Section 3.3 to give 7 (260 mg, 95%) as a col-
orless foam: 1H NMR (CDCl3): d 1.60 (m, 2H,
OCH2CH2CH2N), 3.10 (m, 3H, OCH2CH2CH2N,
OH), 3.50 (m, 1H, OCH2CH2CH2N), 3.65 (m, 1H, H-
6III), 3.70–3.85 (m, 4H, OCH2CH2CH2N, 3H-6), 3.88
(m, 1H, H-5III), 3.95 (m, 3H, 2H-5, H-6), 4.05 (m, 1H,
H-6), 4.35 (dd, 1H, J 8.4 and 10.6, H-2III), 4.45 (m,
2H, 2H-2), 5.02 (s, 2H, CH2Ph), 5.18 (m, 1H, NH),
5.30–5.40 (m, 3H, 3H-4), 5.44 (d, 1H, J 8.4, H-1), 5.52
(d, 1H, J 8.4, H-1), 5.57 (d, 1H, J 8.4, H-1III), 6.10 (m,
2H, 2H-3), 6.24 (t, 1H, J 10.0, H-3III), 7.10–7.50 (m,
22H, aromatics), 7.55–7.92 (m, 25H, aromatics); 13C
Compound 8 (82 mg, 0.02 mmol) was deacetylated as
described in Section 3.3 to give 9 (78 mg, 96%) as a col-
orless foam: [a]D +10 (c 1, CHCl3); Selected 13C NMR
(CDCl3): d 61.30 (C-6VII), 74.21 (C-5VII), 97.33, 97.52,
97.82, 98.03 (C-1). Anal. Calcd for C207H162N8O59: C,
67.10; H, 4.41; N, 3.02. Found: C, 66.95; H, 4.43; N,
3.01.
NMR:
d 29.43 (OCH2CH2CH2N), 37.94 (OCH2-
CH2CH2N), 54.59 (C-2), 54.65 (C-2), 54.73 (C-2),
61.26 (C-6III), 66.30 (CH2Ph), 67.32 (OCH2CH2-
CH2N), 67.75 (C-6), 67.86 (C-6), 69.82 (C-4), 70.30
(C-4), 70.70 (C-4), 71.06 (2C-3), 71.19 (C-3), 72.59
(C-5), 73.34 (C-5), 74.33 (C-5III), 97.55 (C-1III), 97.75
(C-1), 98.04 (C-1), 123.46, 125.27, 127.89, 127.95,
128.37, 128.44, 128.62, 128.71, 128.89, 128.95, 128.99,
130.36, 131.33, 131.55, 133.12, 133.286, 133.345,
134.027, 134.12, 136.86, 156.32, 165.09, 165.46,
165.55, 167.50. Anal. Calcd for C95H78N4O27: C,
66.82; H, 4.60; N, 3.28. Found: C, 66.62; H, 4.62; N,
3.26.
3.11. 3-(Benzyloxycarbonylamino)propyl 6-O-acetyl-3,4-
di-O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyranosyl-
(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-D-
glucopyranosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-
phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-O-benzoyl-
2-deoxy-2-phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-
O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyranoside
(10)
The reaction of disaccharide 2 (96 mg, 0.086 mmol) with
acceptor 7 (130 mg, 0.076 mmol) as described in Section
3.4 resulted in the formation of 10 (188 mg, 90%) as a
colorless foam: [a]D +13 (c 1, CHCl3); Selected 1H
NMR data (CDCl3): d 3.00 (m, 2H, OCH2CH2CH2N),
6.08 (m, 4H, 4H-3), 6.26 (t, 1H, J 9, H-3V); Selected
13C NMR (CDCl3): d 62.55 (C-6V), 71.74 (C-5V),
97.42, 97.54, 97.76, 97.95 (C-1). Anal. Calcd for
3.9. 3-(Benzyloxycarbonylamino)propyl 6-O-acetyl-3,4-
di-O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyranosyl-
(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-D-
glucopyranosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-
phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-O-benzoyl-
2-deoxy-2-phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-
O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyranosyl-
(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-D-
glucopyranosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-
phthalimido-b-D-glucopyranoside (8)
C
153H122N6O44: C, 66.86; H, 4.47; N, 3.06. Found: C,
66.74; H, 4.42; N, 3.05.
3.12. 3-(Benzyloxycarbonylamino)propyl 3,4-di-O-benz-
oyl-2-deoxy-2-phthalimido-b-D-glucopyranosyl-(1!6)-
3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyr-
anosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-
D-glucopyranosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-
phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-O-benzoyl-
2-deoxy-2-phthalimido-b-D-glucopyranoside (11)
Glycosylation of 7 (100 mg, 0.06 mmol) with thioglyco-
side 5 (150 mg, 0.07 mmol) was accomplished as de-
scribed in Section 3.4 to give 8 (165 mg, 74%) as a
colorless foam: [a]D +16 (c 1, CHCl3); Selected 1H
NMR data (CDCl3): d 3.00 (m, 2H, OCH2CH2CH2N),
6.10 (m, 6H, 6H-3), 6.25 (t, 1H, J 10, H-3VII); Selected
Compound 10 (180 mg, 0.02 mmol) was deacetylated as
described in Section 3.3 to give 11 (164 mg, 93%) as a

M. L. Gening et al. / Carbohydrate Research 342 (2007) 567–575
573
colorless foam: [a]D +5 (c 1, CHCl3); Selected 13C NMR
(CDCl3): d 61.27 (C-6V), 74.20 (C-5V), 97.46, 97.58,
97.73, 97.98 (C-1). Anal. Calcd for C151H120N6O43: C,
67.01; H, 4.47; N, 3.10. Found: C, 66.88; H, 4.36; N,
3.10.
C256H206N10O76: C, 67.06; H, 4.37; N, 2.95. Found: C,
67.10; H, 4.40; N, 2.92.
3.15. 3-Acetamidopropyl 2-amino-2-deoxy-b-D-glucopyr-
anosyl-(1!6)-2-amino-2-deoxy-b-D-glucopyranosyl-
(1!6)-2-amino-2-deoxy-b-D-glucopyranosyl-(1!6)-2-
amino-2-deoxy-b-D-glucopyranosyl-(1!6)-2-amino-2-
deoxy-b-D-glucopyranoside (15)
3.13. 3-(Benzyloxycarbonylamino)propyl 6-O-acetyl-3,4-
di-O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyranosyl-
(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-D-gluco-
pyranosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-
b-D-glucopyranosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-
phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-O-benzoyl-
2-deoxy-2-phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-
O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyranosyl-
(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-D-gluco-
pyranosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-
b-D-glucopyranosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-pht-
halimido-b-D-glucopyranosyl-(1!6)-3,4-di-O-benzoyl-2-de-
oxy-2-phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-O-
benzoyl-2-deoxy-2-phthalimido-b-D-glucopyranoside
(12)
Compound 11 (50 mg, 0.018 mmol) was deprotected as
described in Section 3.5 to give 15 (12 mg, 71%) [a]D
ꢁ23 (c 0.5, H2O); Selected 1H NMR data (D2O): d
1.8 (m, 2H, OCH2CH2CH2N), 1.95 (s, 3H, COCH3),
3.0 (m, 5H, 5H-2), 3.2 (m, 1H, OCH2CH2CH2N),
3.29 (m, 1H, OCH2CH2CH2N), 4.23 (m, 4H, 4H-6),
4.70 (m, 5H, 5H-1); Selected 13C NMR (D2O): d
23.13 (NCOCH3), 29.64 (OCH2CH2CH2N), 37.30
(OCH2CH2CH2N), 56.89 (C-2), 61.58 (C-6V), 69.77
(C-6IꢁIV), 100.53, 100.88, 101.35 (C-1). ESI(+)-MS:
calcd for C35H66N6O22: 922.42 [M]; found 923.42
[M+H]+.
Glycosylation of 9 (80 mg, 0.022 mmol) with thioglyco-
side 5 (60 mg, 0.028 mmol) was accomplished as de-
scribed in Section 3.4 to give 12 (63 mg, 51%) as a
colorless foam. [a]D +17 (c 1, CHCl3); Selected 1H
NMR data (CDCl3): d 3.00 (m, 2H, OCH2CH2CH2N),
6.08 (m, 10H, 10H-3), 6.25 (t, 1H, J 9, H-3XI); Selected
13C NMR (CDCl3): d 62.65 (C-6XI), 71.79 (C-5XI),
97.28, 97.65, 97.89 (C-1). Anal. Calcd for C321H248N12-
O92: C, 67.10; H, 4.35; N, 2.93. Found: C, 66.99; H,
4.38; N, 2.95.
3.16. 3-Acetamidopropyl 2-amino-2-deoxy-b-D-glucopyr-
anosyl-(1!6)-2-amino-2-deoxy-b-D-glucopyranosyl-(1!6)-
2-amino-2-deoxy-b-D-glucopyranosyl-(1!6)-2-amino-2-
deoxy-b-D-glucopyranosyl-(1!6)-2-amino-2-deoxy-b-D-
glucopyranosyl-(1!6)-2-amino-2-deoxy-b-D-glucopyr-
anosyl-(1!6)-2-amino-2-deoxy-b-D-glucopyranoside (16)
Compound 8 (53 mg, 0.014 mmol) was deprotected as
described in Section 3.5 to give 16 (16 mg, 93%) [a]D
1
ꢁ22 (c 0.5, H2O); Selected H NMR data (D2O): d 1.8
(m, 2H, OCH2CH2CH2N), 2.95 (m, 7H, 7H-2). Selected
13C NMR (D2O): d 23.14 (NCOCH3), 29.63 (OCH2-
CH2CH2N), 37.32 (OCH2CH2CH2N), 57.06 (C-2),
61.65 (C-6VII), 69.69 (C-6I–VI), 101.00, 101.47, 102.14
(C-1). ESI(+)-MS: calcd for C47H88N8O30: 1244.56
[M]; found 1245.57 [M+H]+.
3.14. 3-(Benzyloxycarbonylamino)propyl 6-O-acetyl-3,4-
di-O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyranosyl-
(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-D-
glucopyranosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-
phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-O-benzoyl-
2-deoxy-2-phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-
O-benzoyl-2-deoxy-2-phthalimido-b-D-glucopyranosyl-
(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalimido-b-D-gluco-
pyranosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-2-phthalim-
ido-b-D-glucopyranosyl-(1!6)-3,4-di-O-benzoyl-2-deoxy-
2-phthalimido-b-D-glucopyranosyl-(1!6)-3,4-di-O-
benzoyl-2-deoxy-2-phthalimido-b-D-glucopyranoside
(13)
3.17. 3-Acetamidopropyl 2-amino-2-deoxy-b-D-glucopyr-
anosyl-(1!6)-2-amino-2-deoxy-b-D-glucopyranosyl-
(1!6)-2-amino-2-deoxy-b-D-glucopyranosyl-(1!6)-2-
amino-2-deoxy-b-D-glucopyranosyl-(1!6)-2-amino-2-
deoxy-b-D-glucopyranosyl-(1!6)-2-amino-2-deoxy-b-D-
glucopyranosyl-(1!6)-2-amino-2-deoxy-b-D-glucopyr-
anosyl-(1!6)-2-amino-2-deoxy-b-D-glucopyranosyl-
(1!6)-2-amino-2-deoxy-b-D-glucopyranoside (17)
The reaction of tetrasaccharide 5 (56 mg, 0.027 mmol)
with acceptor 11 (60 mg, 0.022 mmol) as described in
Section 3.4 resulted in the formation of 13 (63 mg,
60%) as a colorless foam: [a]D +16 (c 1, CHCl3); Selected
Compound 13 (50 mg, 0.011 mmol) was deprotected as
described in Section 3.5 to give 17 (15.8 mg, 95%) [a]D
1
ꢁ27 (c 1, H2O); Selected H NMR data (D2O): d 1.70
1H NMR data (CDCl3):
d
3.03 (m, 2H,
(m, 2H, OCH2CH2CH2N), 2.90 (m, 9H, 9H-2). Selected
OCH2CH2CH2N), 6.12 (m, 8H, 8H-3), 6.27 (t, 1H, J
9, H-3IX); Selected 13C NMR (CDCl3): d 62.59 (C-
6IX), 97.24, 97.61, 97.86, 97.98 (C-1). Anal. Calcd for
13C NMR (D2O):
d
23.62 (NCOCH3), 29.73
(OCH2CH2CH2N), 37.35 (OCH2CH2CH2N), 56.88 (C-
2), 61.62 (C-6IX), 69.88 (C-6I–VIII), 100.63, 101.05 (C-

574
M. L. Gening et al. / Carbohydrate Research 342 (2007) 567–575
1). ESI(+)-MS: calcd for C59H110N10O38: 1566.70 [M];
found 784.36 [M+2H]2+
3.21. 3-Acetamidopropyl 2-acetamido-2-deoxy-b-D-
glucopyranosyl-(1!6)-2-acetamido-2-deoxy-b-D-gluco-
pyranosyl-(1!6)-2-acetamido-2-deoxy-b-D-glucopyrano-
syl-(1!6)-2-acetamido-2-deoxy-b-D-glucopyranosyl-
(1!6)-2-acetamido-2-deoxy-b-D-glucopyranosyl-(1!6)-
2-acetamido-2-deoxy-b-D-glucopyranosyl-(1!6)-2-acet-
amido-2-deoxy-b-D-glucopyranosyl-(1!6)-2-acetamido-
2-deoxy-b-D-glucopyranosyl-(1!6)-2-acetamido-2-
deoxy-b-D-glucopyranoside (21)
.
3.18. 3-Acetamidopropyl 2-amino-2-deoxy-b-D-glucopyr-
anosyl-(1!6)-2-amino-2-deoxy-b-D-glucopyranosyl-
(1!6)-2-amino-2-deoxy-b-D-glucopyranosyl-(1!6)-2-
amino-2-deoxy-b-D-glucopyranosyl-(1!6)-2-amino-2-
deoxy-b-D-glucopyranosyl-(1!6)-2-amino-2-deoxy-b-D-
glucopyranosyl-(1!6)-2-amino-2-deoxy-b-D-glucopyr-
anosyl-(1!6)-2-amino-2-deoxy-b-D-glucopyranosyl-
(1!6)-2-amino-2-deoxy-b-D-glucopyranosyl-(1!6)-2-
amino-2-deoxy-b-D-glucopyranosyl-(1!6)-2-amino-2-
deoxy-b-D-glucopyranoside (18)
Compound 17 (8.8 mg, 0.006 mmol) was N-acetylated
as described in Section 3.5 to form 21 (7.5 mg, 75%):
1
[a]D ꢁ31 (c 0.5, H2O); Selected H NMR data (D2O):
d 1.75 (m, 2H, OCH2CH2CH2N), 4.50 (m, 9H, 9H-1).
Selected 13C NMR (D2O): d 23.17, 23.28, 23.44
(NCOCH3), 56.75 (C-2), 61.88 (C-6IX), 101.92 102.28,
102.64 (C-1). ESI(+)-MS: calcd for C77H128N10O47:
Compound 12 (50 mg, 0.009 mmol) was deprotected as
described in Section 3.5 to give 18 (12 mg, 75%) [a]D
1
ꢁ28 (c 1, H2O); Selected H NMR data (D2O): d 1.80
1944.79 [M]; found 992.41 [M+H+K]2+
.
(m, 2H, OCH2CH2CH2N), 3.00 (m, 11H, 11H-2). Se-
lected 13C NMR (D2O): d 23.07 (NCOCH3), 29.57
(OCH2CH2CH2N), 37.24 (OCH2CH2CH2N), 56.88 (C-
2), 61.53 (C-6XI), 69.60 (C-6I–X), 100.56, 100.93,
101.25, 101.63 (C-1).
3.22. 3-Acetamidopropyl 2-acetamido-2-deoxy-b-D-
glucopyranosyl-(1!6)-2-acetamido-2-deoxy-b-D-gluco-
pyranosyl-(1!6)-2-acetamido-2-deoxy-b-D-glucopyranos-
yl-(1!6)-2-acetamido-2-deoxy-b-D-glucopyranosyl-
(1!6)-2-acetamido-2-deoxy-b-D-glucopyranosyl-(1!6)-
2-acetamido-2-deoxy-b-D-glucopyranosyl-(1!6)-2-acet-
amido-2-deoxy-b-D-glucopyranosyl-(1!6)-2-acetamido-
2-deoxy-b-D-glucopyranosyl-(1!6)-2-acetamido-2-
deoxy-b-D-glucopyranosyl-(1!6)-2-acetamido-2-deoxy-
b-D-glucopyranosyl-(1!6)-2-acetamido-2-deoxy-b-D-
glucopyranoside (22)
3.19. 3-Acetamidopropyl 2-acetamido-2-deoxy-b-D-
glucopyranosyl-(1!6)-2-acetamido-2-deoxy-b-D-gluco-
pyranosyl-(1!6)-2-acetamido-2-deoxy-b-D-glucopyrano-
syl-(1!6)-2-acetamido-2-deoxy-b-D-glucopyranosyl-
(1!6)-2-acetamido-2-deoxy-b-D-glucopyranoside (19)
Compound 15 (6.5 mg, 0.007 mmol) was N-acetylated as
described in Section 3.5 to form 19 (7.5 mg, 95%): [a]D
Compound 18 (5 mg, 0.003 mmol) was N-acetylated as
described in Section 3.5 to form 21 (4.8 mg, 94%);
Selected 1H NMR data (D2O): d 1.75 (m, 2H,
OCH2CH2CH2N), 4.50 (m, 11H, 11H-1). ESI(+)-MS:
calcd for C93H154N12O57: 2350.95 [M]; found 1176.97
1
ꢁ30 (c 0.5, H2O); Selected H NMR data (D2O): d 1.75
(m, 2H, OCH2CH2CH2N), 4.50 (m, 5H, 5H-1); Selected
13C NMR (D2O): d 23.11, 23.35, 23.52 (NCOCH3),
29.42 (OCH2CH2CH2N), 37.61 (OCH2CH2CH2N),
56.66 (C-2), 61.97 (C-6V), 69.77 (C-6I–IV), 102.26,
102.72 (C-1). ESI(+)-MS: calcd for C45H76N6O27:
[M+2H]2+
.
1132.47 [M]; found 586.22 [M+H+K]2+
.
Acknowledgments
This work was supported by the Civilian Research and
Development Foundation (grant # RUB1-2639-MO-
05), the Russian Foundation for Basic Research (grant
# 05-03-08107), and the United States National Insti-
tutes of Health, National Institute for Allergy and Infec-
tious Diseases (Grant # R01 AI46706).
3.20. 3-Acetamidopropyl 2-acetamido-2-deoxy-b-D-
glucopyranosyl-(1!6)-2-acetamido-2-deoxy-b-D-gluco-
pyranosyl-(1!6)-2-acetamido-2-deoxy-b-D-glucopyranos-
yl-(1!6)-2-acetamido-2-deoxy-b-D-glucopyranosyl-
(1!6)-2-acetamido-2-deoxy-b-D-glucopyranosyl-(1!6)-
2-acetamido-2-deoxy-b-D-glucopyranosyl-(1!6)-2-acet-
amido-2-deoxy-b-D-glucopyranoside (20)
References
Compound 16 (7.5 mg, 0.006 mmol) was N-acetylated
as described in Section 3.5 to form 20 (7 mg, 76%);
Selected 1H NMR data (D2O): d 1.75 (m, 2H,
OCH2CH2CH2N), 4.50 (m, 7H, 7H-1). ESI(+)-MS:
calcd for C61H102N8O37: 1538.63 [M]; found 789.31
1. von Eiff, C.; Peters, G.; Heilmann, C. Lancet Infect. Dis.
2002, 2, 677–685.
2. O’Gara, J. P.; Humphreys, H. J. Med. Microbiol. 2001, 50,
582–587.
3. Joyce, J. G.; Abeygunawardana, C.; Xu, Q.; Cook, J. C.;
Hepler, R.; Przysiecki, C. T.; Grimm, K. M.; Roper, K.;
[M+H+K]2+
.

M. L. Gening et al. / Carbohydrate Research 342 (2007) 567–575
575
Ip, C. C. Y.; Cope, L.; Montgomery, D.; Chang, M.;
Campie, S.; Brown, M.; McNeely, T. B.; Zorman, J.;
Maira-Litran, T.; Pier, G. B.; Keller, P. M.; Jansen, K. U.;
Mark, G. E. Carbohydr. Res. 2003, 338, 903–922.
4. Maira-Litran, T.; Kropec, A.; Abeygunawardana, C.;
Joyce, J.; Mark, G.; Goldmann, D. A.; Pier, G. B. Infect.
Immun. 2002, 70, 4433–4440.
5. Maira-Litran, T.; Kropec, A.; Goldmann, D. A.; Pier, G.
B. Vaccine 2004, 22, 872–879.
6. Melean, L. G.; Love, K. R.; Seeberger, P. H. Carbohydr.
Res. 2002, 337, 1893–1916.
8. Kanno, K.; Hatanaka, K. P. Polym. J. (Tokyo) 1998, 8,
678–680.
9. Fridman, M.; Solomon, D.; Yogev, S.; Baasov, T. Org.
Lett. 2002, 4, 281–283.
10. Yang, F.; He, H.; Du, Y. Tetrahedron Lett. 2002, 43,
7561–7563.
11. Yang, F.; Du, Y. Carbohydr. Res. 2003, 338, 495–502.
12. Tsvetkov, Y.; Bukharov, A.; Backinowsky, L.; Kochet-
kov, N. Carbohydr. Res. 1988, 175, C1–C4.
13. Tsvetkov, Y. E.; Backinowsky, L. V.; Kochetkov, N. K.
Carbohydr. Res. 1989, 193, 75–90.
7. Manabe, S.; Ito, Y.; Ogawa, T. Molecules Online 1998, 2,
40–45.
14. Gening, M. L.; Tsvetkov, Y. E.; Pier, G. B.; Nifantiev, N.
E. Russ. J. Bioorg. Chem. 2006, 32, 432–443.