Acid-promoted synthesis of per-O-sulfated fucooligosaccharides related to fucoidan fragments

Article abstract of DOI:10.1016/j.carres.2011.01.005

The synthesis of per-O-sulfated derivatives of di-, tetra-, hexa-, octa-, dodeca-, and hexadecafucosides related to natural fucoidans of different types has been performed with the use of previously reported acid-promoted protocol for per-O-sulfation of p

Full text of DOI:10.1016/j.carres.2011.01.005

Carbohydrate Research 346 (2011) 540–550
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Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Acid-promoted synthesis of per-O-sulfated fucooligosaccharides related
to fucoidan fragments q
Vadim B. Krylov a, Zinaida M. Kaskova c, Dmitry Z. Vinnitskiy c, Nadezhda E. Ustyuzhanina a,
Alexey A. Grachev a, Alexander O. Chizhov b, Nikolay E. Nifantiev a,
⇑
a Laboratory of Glycoconjugate Chemistry, N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991 Moscow, Russia
b Laboratory of NMR spectroscopy, N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991 Moscow, Russia
c Higher Chemical College, Russian Academy of Sciences, Miusskaya sq. 9, 125047 Moscow, Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 4 August 2010
Received in revised form 2 January 2011
Accepted 7 January 2011
Available online 15 January 2011
The synthesis of per-O-sulfated derivatives of di-, tetra-, hexa-, octa-, dodeca-, and hexadecafucosides
related to natural fucoidans of different types has been performed with the use of previously reported
acid-promoted protocol for per-O-sulfation of polyols by SO3 complexes.2 During the treatment of
(1?3)-linked oligofucosides under these conditions with the promotion by TfOH, the unusual rearrange-
ment of the reducing pyranose residue into furanose one was observed. To avoid the formation of rear-
rangement by-products, the use of
a series of strong acids as promoters of sulfation of large
Keywords:
Fucoidans
oligofucosides was studied and the improved protocol was developed based on the use of TFA instead
of TfOH. The efficiency of the new method was demonstrated by the syntheses of per-O-sulfated deriv-
atives of dodeca- and hexadecafucosides. The described method of O-sulfation opens access to the prep-
aration of the oligosaccharides related to fucoidan fragments and their per-O-sulfated derivatives
interesting for elucidation of the relationship between their structure and biological activity.
Ó 2011 Elsevier Ltd. All rights reserved.
Oligofucosides
O-Sulfation
Fucopyranoside
Fucofuranoside
Fucopyranoside-to-fucofuranoside
rearrangement
1. Introduction
complex mixtures of target products together with partly sulfated
ones, which are difficult for preparative separation.
Natural O-sulfated polysaccharides fucoidans from brown
seaweeds and marine invertebrates exhibit a wide range of
biological activities, including anticoagulant, antiangiogenic, and
antimicrobial, as well as the ability to inhibit P- and L-Selectin med-
iated inflammation.3–6 To determine the structure of pharmaco-
phore fragments within the fucoidan chains, we carried out the
systematic synthesis1,7–12 (see Ref. 13 for review), conformational
analysis,8,10–12,14–16 and studies of biological activities of various
oligofucosides related to natural fucoidans.
Recently we have described2 the acid-promoted protocol to
transform the oligosaccharides into their per-O-sulfated derivatives
by the treatmentwith the SO3 complexes inthe presence of triflic acid
(TfOH). In this communication we report the further optimization of
the developed method and its application to the first synthesis of a
series of per-O-sulfated derivatives of oligofucosides related to the
main types of natural fucoidan chains (Scheme 1). The first series of
the compounds consists of di-, tetra-, hexa-, octa-, dodeca-, and
hexadecasaccharides 1b–6b built up of (1?3)-linked a-L-fucopyra-
Highly sulfated oligofucosides represent special interest for bio-
medical investigations because of previous observations that chem-
ically O-sulfated fucoidans exhibit enhanced anticoagulant activity
and could be considered as a possible alternative to most widely
used anticoagulant heparin.6,17 The synthesis of highly and per-
O-sulfatedderivatives of large oligosaccharides still needs the devel-
opment of preparative protocols. The known typical procedures (see
Ref. 2 and papers cited therein) often result in the formation of
nose residues, which correspond to polysaccharides isolated from
seaweeds Laminaria saccharina18,19 (new name Saccharina latissima20),
Chorda filum,21 and Cladosiphon okamuranus.22 The second series of
the compounds is presented by di-, tetra-, and hexasaccharides
7b–9b built up of alternating (1?3)- and (1?4)-linked a-L-fucopyra-
nose residues related to fucoidans from F. evanescens,23 F. distihus,24
and Ascophyllum nodosum.25 In addition, the synthesis of per-
O-sulfated trisaccharide 10b consisted only from (1?4)-linked
a-L-fucopyranose residues like in the fucoidan from L. cichorioides
seaweed was reported and turned out to be highly sulfated and
containing ca. 2 sulfo groups per fucose unit.26 Similar fucan was also
isolated from Arabacia lixula sea urchin.27 Finally, disaccharides 11b
q
Synthesis, NMR, and conformational studies of fucoidan fragments. Part 11. For
Part 10, see Ref. 1.
⇑
and 12b, bearing (1?2)-linked
a-L-fucopyranosyl and a-D-glucuronyl
Corresponding author. Tel./fax: +7 499 135 8784.
E-mail address: nen@ioc.ac.ru (N.E. Nifantiev).
units and representing the branch points of fucoidans from
0008-6215/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2011.01.005

V. B. Krylov et al. / Carbohydrate Research 346 (2011) 540–550
541
OPr
O
OPr
OR
OPr
Me
RO
O
Me
RO
Me
O
O
OR
OR
OR
OPr
OR
OR
O
OR
O
O
Me
O
Me
RO
Me
O
Me
RO
O
OR
OR
OR
OR
O
R = SO3Na
R = H
O
O
n
11a
11b
Me
O
Me
RO
OR
O
Me
O
OR
OR
OR
O
OR
OR
O
OPr
n
Me
RO
O
Me
RO
OR
O
Me
O
OR
O
O
OR
R = H
R = SO3Na
OR
OR
RO
COONa
OR
1a
2a
3a
4a
5a
6a
1b
2b
3b
4b
5b
6b
n = 0
n = 2
n = 4
n = 6
n = 10
n = 14
RO
R = SO3Na
R = H
R = SO3Na
R = H
OR
7a
8a
9a
7b
8b
9b
n = 0
n = 1
n = 2
10a
10b
R = SO3Na
R = H
12a
12b
Scheme 1. Target per-O-sulfated oligosaccharides 1b–12b and their precursors 1a–12a.
L. saccharina18,19 and C. okamuranus,22 respectively, have also been
reported.
olysis to form acceptor 22 (72%). Its glycosylation by donor 18 in
the presence of NIS-TMSOTf gave the substituted hexadecasaccha-
ride 23 in a yield of 74%. The removal of all protective groups in 23
together with the reduction of the allyl group into the propyl one
was performed as described for the preparation of dodecasaccha-
ride 5a to give hexadecasaccharide 6a in a total yield of 54%.
The synthesis of trisaccharide 10a was performed from previ-
ously reported monosaccharide acceptor 24 and disaccharide do-
nor 25 (Scheme 3).7 Coupling of 24 and 25 in the presence of
TMSOTf yielded trisaccharide 26, which was then subjected to
hydrogenolysis and subsequent saponification to give trifucoside
10a.
2. Results and discussion
2.1. Synthesis of oligosaccharide substrates for per-O-sulfation
studies
The synthesis of target oligosaccharides 1b–12b was per-
formed from the corresponding parent non-sulfated compounds
1a–12a. Highly stereoselective syntheses of disaccharides 1a, 7a,
11a, and 12a, tetrasaccharides 2a and 8a, hexasaccharides 3a
and 9a, and octasaccharide 4a were reported in our previous
communications.1,7,24
2.2. Synthesis of per-O-sulfated oligosaccharides 1b–12b
The synthesis of dodeca- and hexadecasaccharides 5a and 6a
was performed from the protected precursors 13,28 17,7 and 197
(Scheme 2) according to the main procedures, which were previ-
ously used by us for the synthesis of oligofucosides.7 Thus, mono-
saccharide 1328 was subjected to 3-O-chloroacetylation followed
by bromination with N-bromosuccinimide (NBS) and hydrolysis
in aq acetone29 followed by the subsequent treatment with CCl3CN
to give trichloroacetimidate 14 in a overall yield of 72% (Scheme 3).
The TMSOTf-catalyzed glycosylation of 13 with 14 was performed
at ꢀ90 °C and gave disaccharide 15 in a moderate yield of 66%. Low
temperature allowed us to increase the selectivity of the reaction
and to minimize the formation of the by-product resulted from
the undesirable SEt-transfer (not shown). The obtained product
15 was then transformed into acceptor 16 by the selective removal
of the chloroacetyl group with NH2CSNH2 and 2,4,6-collidine in
methanol at 60 °C with an almost quantitative yield. Coupling of
disaccharides 16 and 17 was performed as described for the syn-
thesis of compound 15 and afforded tetrasaccharide donor 18 in
a yield of 55%.
Preparation of per-O-sulfated disaccharides 1b and 11b from
the corresponding unprotected compounds 1a and 11a was re-
ported to be efficient under the treatment with the PyꢁSO3 complex
in DMF at room temperature.14 The same conditions were shown
to be inapplicable for per-O-sulfation of tetrasaccharide 2a and re-
sulted in the formation only of a mixture of partially sulfated deriv-
atives.2 The temperature increase and the variation of the solvents
and sulfation reagents afforded no per-O-sulfated tetrasaccharide
2b.2
Recently, we reported a new protocol for the per-O-sulfation of
polyols of different types with the use of the complex Et3NꢁSO3
(5.0 equiv per OH group) in DMF at 0 °C in the presence of TfOH
(1.0–1.6 equiv per OH group).2 The addition of strong acid to the
reaction mixture was assumed to deliberate unbound SO3 and
facilitate the per-O-sulfation of polyols. In particular, we demon-
strated that linear tetrafucoside 2a can be transformed into per-
O-sulfated derivative 2b in a good yield.2 In continuation of this
work, we studied the acid-promoted per-O-sulfation of larger oli-
gosaccharides (3a–6a).
Contrary to the result of the per-O-sulfation of disaccharide 1a
(Table 1, entry 1, see also Fig. 1) and tetrasaccharide 2a,2 a similar
reaction with hexa- and octasaccharides resulted in the formation
of a mixture of partly O-sulfated products. Our attempts to use a
larger amount of an acidic promoter gave rise to the formation of
an unexpected product with the unusual set of signals in 1H and
13C NMR spectra. To assess its structure, the sulfation of di-(1a)
and tetrasaccharide 2a in the presence of a larger amount of TfOH
were studied further.
The acidic methanolysis of previously obtained 197 afforded
octasaccharide acceptor 20, which was further glycosylated by do-
nor 18 to give dodecasaccharide 21 in a yield of 69%. This product
was subjected to the catalytic hydrogenolysis and reduction of the
allyl group into the propyl one followed by the saponification of
the benzoyl and acetyl groups. Additional hydrogenolysis of the
obtained product was performed to remove the residual benzyl
groups, which remained in a low extent as the result of low solu-
bility of partly debenzylated intermediates under the hydrogenol-
ysis conditions. Finally, deprotected dodecasaccharide 5a was
obtained in a total yield of 61%.
Thus, the treatment of 1a in the presence of TfOH in an amount
of 2 equiv per OH group resulted in the formation of a 3.2:1
mixture of two disaccharide products 1b and 27 (Scheme 4 and
For the synthesis of hexadecasaccharide 6a, the O-acetyl group
in dodecasaccharide 21 was selectively removed by acidic methan-

542
V. B. Krylov et al. / Carbohydrate Research 346 (2011) 540–550
NH
CCl3
Me
SEt
O
OBn
O
Me
SEt
O
OH
OBn
Me
BzO
O
OBn
O
13
BzO
O
ii
O
BzO
O
Me
OBn
Me
i
OBn
17
OR
BzO
NH
OAc
BzO
15
R = COCH2Cl
O
CCl3
iii
16 R = H
Me
O
OBn
OCOCH2Cl
BzO
14
ii
OAll
OBn
Me
O
OAll
OBn
O
BzO
O
Me
Me
SEt
O
O
Me
OBn
OBn
O
O
BzO
BzO
O
O
BzO
O
Me
O
6
Me
OBn
Me
OBn
OBn
O
O
BzO
BzO
O
n
OR
2
BzO
Me
BzO
Me
O
OBn
OBn
19 R = Ac
20
iv
OR
OAc
BzO
R = H
vi
iv
18, v
v
5a
18
21 n=10 R = Ac
22
23
n=10 R = H
n=14 R = Ac
vi
6a
Scheme 2. Synthesis of dodeca- and hexadecasaccharides 5a and 6a. Reagents and conditions: (i) (1) CH2ClCOCl, Py, CH2Cl2; (2) NBS, acetone–water; (3) CCl3CN, DBU, CH2Cl2,
ꢀ40 °C, 2 h, 72%; (ii) TMSOTf, ꢀ90 °C, 1 h, 66% for 15 and 55% for 18; (iii) NH2CSNH2, 2,4,6-collidine, MeOH, 60 °C, 24 h, 94%, (iv) HCl, MeOH, 20 °C, 6 h, 76% for 20, 72% for 22;
(v) NIS, TfOH, CH2Cl2, ꢀ40 °C, 2 h, 69% for 21 and 74% for 23; (vi) (1) H2, Pd/C, THF–EtOH–AcOH, 20 °C, 5 h, (2) NaOH, CH2Cl2–EtOH–H2O, 60 °C, 12 h; (3) H2, Pd/C, MeOH–
AcOH, 20 °C, 5 h, 61% for 5a and 54% for 6a.
(Fig. 1) and was accompanied by the formation of decomposition
products.
OAll
OBn
Me
HO
O
OAll
OBn
The formation of similar side product 28 was more intensive in
the case of homologous tetrasaccharide 2a. Thus, the acid-promoted
sulfation of 2a by the Et3NꢁSO3 complex (5 equiv per OH group) in
the presence of TfOH (2 equiv per OH group) during 48 h resulted
in the formation of product 28 only, which was confirmed by mass
spectrometry and NMR spectroscopy. Very surprisingly, their data
OBz
Me
O
24
OBz
O
i
+
Me
O
NH
CCl3
OBn
O
OBz
O
show that compound 28 has the terminal 2,5-di-O-sulfated
a-L-
Me
O
OBn
Me
O
fucofuranose unit in the ‘reducing end’. Its structure was confirmed
by characteristic resonances for fucofuranose of H-4 (4.02 ppm, t)
and C-4 (83.9 ppm) in the 1H and 13C NMR spectra (see Fig. 2 and
Table 2).30,31 Moreover, the presence of the five-membered ring
was evidenced by a correlation of H-1–C-4 as well as C-1–H-4 in
HMBC NMR experiments. Spatial proximity of H-4 with H-2 was
observed from NOE NMR experiments. Signals of molecular ion in
ESI-MS also confirmed that products 2b and 28 are the isomers.
Similarly to the transformation 2a?28, the treatment of hexa-
saccharide 3a and octasaccharide 4a by the Et3NꢁSO3 complex
(5 equiv per OH group) in the presence of TfOH (2 equiv per OH
group) during 48 h at 0 °C resulted to their complete conversion
into the corresponding rearranged derivatives 29 and 30 in yields
of ꢂ70%. The observed unusual rearrangement of the fucopyrano-
side residue into the fucofuranoside one with the cleavage of the
cyclic C(1)–O(5) bond followed by the recyclization and formation
of a new O(4)–C(1) bond but without affecting propyl aglycon be-
longs to a rare type of reactions in carbohydrate chemistry.32–34
This transformation is contrary to the usual situation when the
cleavage of the acyclic C(1)–O(1) glycoside bond proceeds more in-
tensely than that of the cyclic C(1)–O(5) bond. It is noticeable that
the described transformation proceeds selectively only with the
fucopyranoside unit at the reducing end but not with other ones
OBn
OBz
O
OAc
ii
BzO
Me
26
10a
O
OBn
OAc
BzO
25
Scheme 3. Synthesis of trifucoside 10a. Reagents and conditions: (i) TMSOTf,
ꢀ40 °C, 3 h, 77%; (ii) (1) H2, Pd/C, MeOH–EtOAc, 20 °C, 5 h, (2) NaOH, MeOH–H2O,
20 °C, 24 h, 75%.
Table 1
Acid-promoted sulfation of disaccharide 1a by Et3NꢁSO3 (5 equiv per OH group) in
DMF at 0 °C and formation of side product 27
Entry Amount of acid (equiv per
OH group)
Time
(h)
Products
Yield (%)
1
2
3
1.0
2.0
2.0
24
24
186
1b
77
82
1b:27 = 3.1:1
1b:27 = 1:2.3 + decomposition
Table 1, entry 2). Increasing in the reaction time to 168 h (1 week)
favored to accumulate side product 27 (entry 3, ratio 1:27 = 1:2.3)

V. B. Krylov et al. / Carbohydrate Research 346 (2011) 540–550
543
presented in the oligosaccharide chains under investigation. The
discussed process does not have direct analogy among chemical
reactions, only enzymatic transformation ‘fucopyranoside?fuco-
furanoside’ without cleavage of aglycon is known.35 Detailed
investigation of the mechanism and scopes of the observed rear-
rangement is in progress and will be reported elsewhere.
It could be expected that the optimization of an acidic promoter
used for the activation of the sulfating reagent can improve the
yield of the target non-rearranged per-O-sulfated products. Using
of chlorosulfonic acid (1.0 equiv per OH group) as a promoter also
gave compound 29 in a yield of 83% without any significant
amounts of product 3b (Table 3, entry 1). Sulfation promoting
activities of both H2SO4 and BF3ꢁEt2O in an amount of 1.0 equiv
per OH group were insufficient to perform per-O-sulfation and pro-
duced a complex mixture of partly sulfated products (Table 3, en-
tries 2 and 3). Fortunately, the use of weaker trifluoroacetic acid
(TFA) led to desired product 3b. Thus, its use in an amount of
1.0 equiv per OH group formed a 5:1 mixture (1H NMR monitoring)
of 3b and 29 (Table 3, entry 4), while a decrease in the amount of
TFA down to 0.5 equiv per OH group gave 76% of desired 3b as the
only formed product (Table 3, entry 5).
Promotion with TFA, which was used in the synthesis of hexa-
saccharide 3b (Table 3, entry 5), was successfully applied to the
synthesis of per-O-sulfated octasaccharide 4b (yield 78%), dodeca-
saccharide 5b (yield 72%), and hexadecasaccharide 6b (yield 75%)
from parent unsubstituted oligofucosides 4a–6a. Compounds 4b,
5b, and 6b had one product in the 1H NMR spectra with the signal
Figure 1. Parts of 1H NMR spectra of the products of TfOH-promoted per-O-
sulfation of disaccharide 1a described in Table 1: (A) entry 1 (only product 1a is
formed), (B) entry 2 and (C) entry 3.
Me
OSO3Na
groups presented in the spectra of previously synthesized
a-
OPr
O
(1?3)-linked oligofucosides 2b and 3b. The ratio of integral inten-
sities of H-1 signals for ‘reducing’ unit (d 5.21, d) and non-reducing
units (d 5.40, br s) corresponded well to a number of fucopyranose
residues in oligosaccharides 4b–6b (Fig. 3).
OSO3Na
O
Me
O
OSO3Na
Per-O-sulfation of oligosaccharides 8a and 9a related to the sec-
O
NaO3SO
O
n
ond type of fucoidan backbone consisted of alternating
and -(1?3)-linked fucopyranose residues and only of
a
a
-(1?4)-
-(1?4)-
Me
a
OSO3Na
OSO3Na
linked compounds 7a and 10a were studied further starting first
from disaccharide 7a. Both TFA and TfOH acids were tested as
promoters to give desired pentasulfate 7b in a yield of 80% and
83%, respectively (Table 4, entries 1 and 2). No rearrangement of
the terminal fucopyranose residue (at the ‘reducing’ end) into the
fucofuranose one is possible for compounds 7a–10a because of the
4-O-substitution of this unit in these compounds. Therefore, for
these examples TfOH was used as the promoter of sulfation in an
amount of 1 equiv per OH group to give per-O-sulfated tetra- and
NaO3SO
1b
2b
3b
4b
1a
2a
3a
4a
27 n = 0
28 n = 2
29 n = 4
30
n = 6
Scheme 4. Products of the TfOH-promoted per-O-sulfation of oligofucosides 1a–4a.
Figure 2. Comparison of 1H NMR spectra of isomeric tetrasaccharides 2b and 28.

544
V. B. Krylov et al. / Carbohydrate Research 346 (2011) 540–550
Table 2
Selected spectral characteristics of 2b and 28
Structure
Selected NMR data
OPr
1
H-1
5.21
C-1
97.4
JH-1,H-2
3.4 Hz
H-2
4.52
C-2
76.2
JH-4,H-5
ꢂ1 Hz
H-3
4.28
C-3
76.1
JC-4,H-1
—
H-4
4.90
C-3
81.3
JC-1,H-4
—
H-5
4.22
C-5
68.3
JC-5,H-1
6.9 Hz
H-6
1.30
C-6
17.0
JC-1,H-5
—
O–CH2–Et
3.55; 3.63
O–CH2–Et
71.9
6
Me
4
5
O
OSO3Na
O 3
2
NaO3SO
2b
6Me
5
H-1
5.23
C-1
101.2
JH-1,H-2
4.4 Hz
H-2
4.77
C-2
81.6
JH-4,H-5
6.0 Hz
H-3
4.43
C-3
81.2
JC-4,H-1
7.0 Hz
H-4
4.02
C-3
83.9
JC-1,H-4
3.2 Hz
H-5
4.61
C-5
78.6
JC-5,H-1
—
H-6
1.45
C-6
18.0
JC-1,H-5
—
O–CH2–Et
3.47; 3.82
O–CH2–Et
71.8
OSO3Na
1OPr
O
4
3
OSO3Na
2
O
28
Table 3
Sulfation of hexasaccharide 3a with Et3NꢁSO3 (5 equiv per OH group) in DMF at 0 °C promoted by different acids
Entry
Acid
Amount of acid (equiv per OH group)
Products
29
Yield (%)
1
2
3
4
5
ClSO3H
H2SO4
BF3ꢁEt2O
TFA
1.0
1.0
1.0
1.0
0.5
83
Mixture of partially sulfated products
Mixture of partially sulfated products
3b:29 ꢂ 5:1
73
76
TFA
3b
hexasaccharides 8b, 9b, and 10b in 84%, 83%, and 75% yields,
respectively (Table 4, entries 3–5). Comparable results were
obtained also in the preparation of per-O-sulfated disaccharides
11b and 12b (Table 4, entries 6 and 7).
were purified according to conventional procedures.36 NMR spec-
tra for substituted compounds were recorded on AM-300, DRX-
500, and Avance 600 Bruker spectrometers at 303 K. NMR spectra
for non-protected oligosaccharides 5a and 10a were recorded in
D2O, for 6a in CD3OD on a DRX-500 Bruker spectrometer. NMR
spectra for sulfated oligosaccharides 1b–12b, 27–30 were recorded
in D2O on DRX-500 and Avance 600 Bruker spectrometers. Gradi-
ent enhanced 2D gCOSY, gNOESY, and gHSQC experiments, as well
as TOCSY experiments, were used for resonance assignment. High
resolution mass spectra (HR MS) were measured on a Bruker
micrOTOF II instrument using electrospray ionization (ESI).37 The
measurements were done in a positive ion mode (interface capil-
lary voltage—4500 V) or in a negative ion mode (3200 V); mass
range from m/z 50 to m/z 3000 Da; external or internal calibration
was done with Electrospray Calibrant Solution (Fluka). A syringe
injection was used for solutions in a mixture of acetonitrile and
3. Conclusion
The synthesis of per-O-sulfated oligosaccharides 1b–12b re-
lated to various types of fucoidans is described. Preparation of tar-
get products is achieved by using acid-promoted sulfation suitable
for oligosaccharides of different types. The described acid-pro-
moted sulfation protocol appeared to be a powerful method for
the per-O-sulfation of large oligosaccharides, which is not accessi-
ble in the preparative scale by previously known methods. The un-
known rearrangement of the fucopyranose unit at the reducing end
into the fucofuranose one was observed and the efficiency of this
process depended on the type of the used acid promoter. The var-
iation of the type and amount of the acidic promoter allows the
direct formation of per-O-sulfated rearranged 28–30 or non-rear-
ranged 1b–6b oligosaccharides to access. The sulfation of oligosac-
charides 7a–12a with 4-O- or 2-O-substituted terminal residues
was free from any side processes and gave per-O-sulfated deriva-
tives 7b–12b in a good yield. The results of conformational and
biological studies of synthetic fucoidan fragments 1b–12b will be
published elsewhere.
water (50:50 v/v flow rate 3 lL/min). Nitrogen was applied as a
dry gas; interface temperature was set at 180 °C. All reactions
involving air- or moisture-sensitive reagents were carried out
using dry solvents under dry argon.
4.2. Preparation of protected oligosaccharides
4.2.1. 4-O-Benzoyl-2-O-benzyl-3-O-chloroacetyl-L-
fucopyranosyl trichloroacetimidate (14)
To a soln of monosaccharide 13 (400 mg, 1.00 mmol) in anhy-
drous CH2Cl2 (10 mL), Py (320 L, 4.0 mmol) and chloroacetylchlo-
ride (160 L, 2.0 mmol) were added. After 1 h the mixture was
l
4. Experimental
l
diluted with CHCl3 and washed successively with 1 M HCl, satd
NaHCO3, and water. The solvent was evaporated and the residue
was chromatographed (10:1 toluene–EtOAc) to give the chloro-
acetylated derivative as a yellowish foam. Then it was dissolved
in (1:9) H2O–acetone CH3COCH3 (20 mL) and N-bromosuccinimide
(535 mg, 3.00 mmol) was added at 0 °C. The mixture was vigor-
ously stirred for 10 min, then diluted with CH2Cl2 and washed with
aq NaHCO3 (3 ꢃ 100 mL). The organic phase was dried over anhyd
Na2SO4 and concentrated under diminished pressure giving a
white residue. To a soln of the above residue in anhyd CH2Cl2
4.1. General methods
TLC was performed on Silica Gel 60 F254 (Merck) with toluene-
EtOAc and with detection by charring with H3PO4. Liquid chroma-
tography was performed on Silicagel 60–200 lm (Fluka) by
gradient elution with toluene-EtOAc. Gel chromatography was
performed on a BioBeads SX-3 (Bio Rad) column (2 ꢃ 70 cm) by
elution with toluene at a flow rate of 1 mL/min and on a Sephadex
G-15 column (3.5 ꢃ 50 cm) by elution with water at a flow rate of
1 mL/min. Optical rotations were determined with a Jasco DIP-360
digital polarimeter at 26–30 °C. All solvents used for the syntheses
(5 mL) CCl3CN (1 mL, 10.0 mmol) and DBU (75 lL, 0.50 mmol)

V. B. Krylov et al. / Carbohydrate Research 346 (2011) 540–550
545
3H, J5,6 6.4 Hz, H-6), 3.75–3.90 (m, 2H, CH2Cl), 4.02 (t, 1H, J1,2, J2,3
8.1 Hz, H-2), 4.10 (q, 1H, J5,6 6.4 Hz, H-5), 4.65, 4.91 (2d, 2H, J
11.3 Hz, CH2Ph), 5.25 (dd, 1H, J2,3 8.1 Hz, J3,4 3.3 Hz, H-3), 5.51 (d,
1H, J3,4 3.3 Hz, H-4), 5.91 (d, 1H, J1,2 8.1 Hz, H-1), 7.20–8.10 (m,
10H, 2Ph), 8.77 (s, 1H, @NH). Anal. Calcd for C24H23Cl4NO7: C,
49.76; H, 4.00; N, 2.42. Found: C, 49.52; H, 4.07; N, 2.64.
4.2.2. Ethyl 4-O-benzoyl-2-O-benzyl-3-O-chloroacetyl-a-
L-fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-1-thio-b-
L-fucopyranoside (15)
A mixture of MS 4 Å (500 mg), thioglycoside acceptor 13
(300 mg, 0.75 mmol), and donor 14 (400 mg, 0.69 mmol) in CH2Cl2
(8 mL) was stirred for 30 min at room temperature, cooled to
ꢀ90 °C, and then TMSOTf (50
lL, 0.26 mmol) was added dropwise.
The resulting mixture was stirred at ꢀ90 to ꢀ80 °C until the disap-
pearance of starting 14 (TLC monitoring), quenched with Et3N, di-
luted with CHCl3, and filtered through a Celite layer. Column
chromatography of the residue (5:1 petroleum ether–EtOAc) affor-
ded 15 (373 mg, 66%) as a colorless foam; [
a
]
D ꢀ214 (c 1.0, EtOAc).
1H NMR (300 MHz, CDCl3): d 0.82 (d, 3H, J5,6 6.5 Hz, H-6II), 1.28 (d,
3H, J5,6 6.8 Hz, H-6I), 1.42 (t, 3H, J 7.4 Hz, CH2CH3), 2.82–2.98 (m,
2H, CH2CH3), 3.66–3.79 (m, 2H, CH2Cl), 3.80–3.96 (m, 3H, H-2I,
H-5I, H-2II), 4.04 (dd, 1H, J2,3 9.4 Hz, J3,4 3.2 Hz, H-3I), 4.27 (q, 1H,
J5,6 6.5, H-5II), 4.32, 4.50 (2d, 2H, J 12.5 Hz, CH2Ph), 4.60 (d, 1H,
J1,2 9.6 Hz, H-1I), 4.71, 5.14 (2d, 2H, J 9.7 Hz, CH2Ph), 5.18 (d, 1H,
J4,3 3.4 Hz, H-4II), 5.39 (d, 1H, J1,2 3.5 Hz, H-1II), 5.48 (dd, 1H, J2,3
10.5 Hz, J3,4 3.4 Hz, H-3II), 5.69 (d, 1H, J3,4 3.2, H-4I), 7.05–8.10
(m, 20H, 4Ph). Anal. Calcd for C44H47ClO11S: C, 64.50; H, 5.78.
Found: C, 64.70; H, 5.90.
4.2.3. Ethyl 4-O-benzoyl-2-O-benzyl-
4-O-benzoyl-2-O-benzyl-1-thio– -fucopyranoside (16)
A mixture of disaccharide 15 (170 mg, 0.21 mmol), 2,4,6-colli-
dine (30 L, 0.22 mmol), and thiourea (77 mg, 1.01 mmol) in MeOH
a-L-fucopyranosyl-(1?3)-
L
l
(6 mL) and CHCl3 (1 mL) was boiled under reflux for 24 h, cooled,
and evaporated to dryness. A soln of the residue in CHCl3 was
washed with 1 M HCl and satd NaHCO3 and concentrated. The resi-
due was purified by column chromatography (5:1 toluene–EtOAc)
Figure 3. Parts of 1H NMR spectra of per-O-sulfated octa-, dodeca-, and hexadeca-
saccharides 4b–6b with the integration of anomeric signals of reducing and non-
reducing residues.
to give 16 (145 mg, 94%) as a white foam; [
a
]
D ꢀ174 (c 1.0, EtOAc).
1H NMR (500 MHz, CDCl3): d 0.91 (d, 3H, J5,6 6.5 Hz, H-6II), 1,25 (d,
3H, J5,6 6.3 Hz, H-6I), 1.38 (t, 3H, J 7.5 Hz, CH2CH3), 2.00 (s br, 1H,
OH), 2.78–2.91 (m, 2H, CH2CH3), 3.75 (dd, 1H, J1,2 3.1 Hz, J2,3 10 Hz,
H-2II), 3.78–3.84 (m, 2H, H-2I, H-5I), 4.03 (dd, 1H, J2,3 9.4, J3,4
3.0 Hz, H-3I), 4.09–4.14 (m br, 1H, H-3II), 4.21 (q, 1H, J5,6 6.5 Hz,
H-5II), 4.35, 4.54 (2d, 2H, J 12.0 Hz, CH2Ph), 4.57 (d, 1H, J1,2 9.6
Hz, H-1I), 4.66, 5.07 (2d, 2H, J 10.3 Hz, CH2Ph), 5.04 (d, 1H, J3,4
3.7 Hz, H-4II), 5.43 (d, 1H, J1,2 3.1 Hz, H-1II), 5.69 (d, 1H, J3,4 3.0 Hz,
H-4I), 7.10–8.10 (m, 20H, 4Ph). Anal. Calcd for C42H46O10S: C,
67.91; H, 6.24. Found: C, 68.04; H, 6.49.
Table 4
Acid-promoted sulfation of oligosaccharides 7a–12a by the treatment with 5 equiv
per OH group Et3NꢁSO3 in DMF
Entry
Saccharide
Acid
Amount of acid
Product
Yield (%)
(equiv per OH group)
1
2
3
4
5
6
7
7a
7a
8a
9a
10a
11a
12a
TFA
0.5
1.0
1.0
1.0
1.0
1.0
1.0
7b
7b
8b
9b
10b
11b
12b
80
83
84
83
75
72
85
TfOH
TfOH
TfOH
TfOH
TfOH
TfOH
4.2.4. Ethyl 3-O-acetyl-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
-fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-a-L-
a-L-
a
-L
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-1-thio–L-
fucopyranoside (18)
Glycosylation of difucoside 16 (130 mg, 0.175 mmol) with tri-
chloroacetimidate 17 (170 mg, 0.192 mmol) as described for the
preparation of 15 gave tetrasaccharide 18 (141 mg, 55%) as a yel-
were added under an argon atmosphere, and the mixture was then
stirred for 2 h. The concentration of the reaction mixture followed
by purification of the residue by column chromatography (5:1
petroleum ether–EtOAc) gave 14 (415 mg, 72% over three steps,
lowish syrup; [
a
]
D ꢀ235 (c 1.0, EtOAc). 1H NMR (500 MHz, CDCl3):
d 0.55 (d, 3H, J5,6 6.4 Hz, H-6IV), 0.85 (d, 6H, J5,6 6.5 Hz, H-6II–III),
1.24 (d, 3H, J5,6 6.5 Hz, H-6I), 1.37 (t, 3H, J 7.4 Hz, CH2CH3), 2.02
(s, 3H, COCH3), 2.75–2.90 (m, 2H, CH2CH3), 3.76 (dd, 1H, J1,2
3.4 Hz, J2,3 10.5, H-2IV), 3.78–3.84 (m, 2H, H-2I, H-5I), 3.92–4.00
(m, 2H, H-2II–III), 4.01 (dd, 1H, J2,3 9.4 Hz, J3,4 3.0 Hz, H-3I), 4.12–
4.21 (m, 5H, H-5II–IV, H-3III, PhCHH0), 4.32–4.42 (m, 4H, 3 ꢃ PhCHH0,
H-3II), 4.53–4.68 (m, 4H, 3 ꢃ PhCHH0, H-1I), 5.00 (d, 1H, J3,4 3.1 Hz,
a
/b = 1.4:1) as a syrup; 1H NMR (300 MHz, CDCl3):
a-isomer—d
1.24 (d, 3H, J5,6 6.3 Hz, H-6), 3.91–3.97 (m, 2H, CH2Cl), 4.18 (dd,
1H, J1,2 3.6 Hz, J2,3 7.9 Hz, H-2), 4.48 (q, 1H, J5,6 6.3 Hz, H-5),
4.63–4.76 (m, 2H, CH2Ph), 5.55 (dd, 1H, J2,3 7.9 Hz, J3,4 3.2 Hz, H-
3), 5.63 (d, 1H, J3,4 3.2 Hz, H-4), 6.61 (d, 1H, J1,2 3.6 Hz, H-1),
7.20–8.10 (m, 10H, 2Ph), 8.66 (s, 1H, @NH); b-isomer—d 1.32 (d,

546
V. B. Krylov et al. / Carbohydrate Research 346 (2011) 540–550
H-4IV), 5.07–5.11 (m, 2H, H-1IV, PhCHH0), 5.16 (d, 1H, J3,4 2.6 Hz, H-
4III), 5.24 (dd, 1H, J2,3 10.5 Hz, J3,4 3.1 Hz, H-3IV), 5.28–5.31 (m, 3H,
H-1II–III, H-4II), 5.67 (d, 1H, J4,5 3.0 Hz, H-4I), 7.00–8.12 (m, 40H,
8Ph). Anal. Calcd for C84H88O21S: C, 68.84; H, 6.05. Found: C,
68.61; H, 5.91.
4.2.7. Allyl 4-O-benzoyl-2-O-benzyl-
O-benzoyl-2-O-benzyl- -fucopyranosyl-(1?3)-4-O-benzoyl-2-
O-benzyl- -fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
-fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
a-L-fucopyranosyl-(1?3)-4-
a-L
a
-L
a-
L
a
-
-
-
-
-
-
-
-
L
-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranoside (22)
a
a
a
a
a
a
a
-
L
L
L
L
L
L
L
-
-
-
-
-
-
4.2.5. Allyl 4-O-benzoyl-2-O-benzyl-
O-benzoyl-2-O-benzyl- -fucopyranosyl-(1?3)-4-O-benzoyl-2-
O-benzyl- -fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
-fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
a-L-fucopyranosyl-(1?3)-4-
a-L
a
-
L
a-
L
a
-
-
-
-
L-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranoside (20)
a
a
a
-
L
L
L
-
-
O-Deacetylation of 21 (108 mg, 0.026 mmol) was performed as
described for the preparation of 20 to give dodecasaccharide 22
Anhyd HCl in MeOH (0.5 M, 5.2 mL), obtained by adding AcCl
(200 L, 2.8 mmol) to chilled MeOH (5 mL), was added to a soln
(77 mg, 72%); [
a]
D ꢀ288 (c 1.0, EtOAc). 1H NMR (600 MHz, CDCl3):
l
d 0.63–0.73 (m, 27H, 8 ꢃ H-6), 0.78, 1.09, 1.20, (3d, 9H, J5,6 6.5 Hz,
3 ꢃ H-6), 3.63–4.88 (m, 62H, 12 ꢃ H-2, 12 ꢃ H3, 12 ꢃ H-5,
12 ꢃ PhCH2, CH2@CH–CH2), 4.98–5.44 (m, 24H, 12 ꢃ H-1, 10 ꢃ H-
4, CH2@CH–CH2), 5.51 (s br, 1H, H-4), 5.72 (s br, 1H, H-4), 5.96–
6.04 (m, 1H, CH2@CH–CH2), 6.98–8.10 (120H, 24 ꢃ Ph). Selected
13C NMR data (150 MHz, CDCl3): d 15.8–16.3 (12 ꢃ C-6), 91.6–
93.3 (11 ꢃ C-1), 96.6 (C-1), 117.7 (CH2@CH–CH2). Anal. Calcd for
C243H246O61: C, 70.45; H, 5.99. Found: C, 70.35; H, 6.13.
of 19 (245 mg, 0.087 mmol) in anhyd CH2Cl2 (2 mL). The resulting
mixture was kept for 6 h at ambient temperature, diluted with
CHCl3, washed with satd NaHCO3 and water, and concentrated.
Column chromatography of the residue (10:1 toluene–EtOAc) gave
20 (184 mg, 76%) as a colorless foam; [
a]
ꢀ287 (c 1.0, EtOAc). 1H
D
NMR (500 MHz, CDCl3): d 0.52–0.65 (m, 12H, 4 ꢃ H-6), 0.68, 0,99,
1.11, 1.20 (4d, 12H, J5,6 6.5 Hz, 4 ꢃ H-6), 3.55–4.52 (m, 42H,
8 ꢃ H-2, 8 ꢃ H3, 8 ꢃ H-5, 8 ꢃ PhCH2, CH2@CH–CH2), 4.70–5.35
(m, 16H, 8 ꢃ H-1, 6 ꢃ H-4, CH2@CH–CH2), 5.42 (s br, 1H, H-4),
5.63 (s br, 1H, H-4), 5.87–6.00 (m, 1H, CH2@CH–CH2), 6.90–8.00
(80H, 16 ꢃ Ph). Selected 13C NMR data (125 MHz, CDCl3): d 15.6–
16.0 (8 ꢃ C-6), 91.9–93.2 (7 ꢃ C-1), 96.3 (C-1), 117.7 (CH2@CH–
CH2). Anal. Calcd for C163H166O41: C, 70.40; H, 6.02. Found: C,
70.23; H, 6.09.
4.2.8. Allyl 3-O-acetyl-4-O-benzoyl-2-O-benzyl-a-L-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranoside (23)
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
-L-
-L
-L
-L
-L
-L
-L
-L
-L
-L
-L
-L
-L
-L
-L
-
-
-
-
-
-
-
-
-
-
-
-
-
-
4.2.6. Allyl 3-O-acetyl-4-O-benzoyl-2-O-benzyl-a-L-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?3)-4-O-benzoyl-2-O-benzyl-
fucopyranoside (21)
a
a
a
a
a
a
a
a
a
a
a
-L-
-
-
-
-
-
-
-
-
-
-
L-
L-
L-
L-
L-
L-
L-
L-
L-
L
-
Glycosylation of dodecasaccharide 22 (70 mg, 0.0169 mmol)
with tetrasaccharide 18 (27 mg, 0.182 mmol) was performed as
described for the preparation of 21 and gave hexadecasaccharide
To
a soln of 21 (172 mg, 0.062 mmol) and 18 (91 mg,
23 (69 mg, 74%) as a yellowish syrup; [
a
]
ꢀ277 (c 1.0, EtOAc).
D
0.062 mmol) in CH2Cl2 (3 mL), MS 4 Å (300 mg) was added, and
the resulting mixture was stirred for 30 min at rt. After cooling
to ꢀ15 °C NIS (21 mg, 0.093 mmol) was added, and the mixture
was stirred for 10 min. Then the temperature of the reaction mix-
1H NMR (600 MHz, CDCl3): d 0.58 (d, 3H, J5,6 6.4 Hz, H-6), 0.62–
0.73 (m, 36H, 12 ꢃ H-6), 0.78, 1.08, 1.20, (3d, 9H, J5,6 6.5 Hz,
3 ꢃ H-6), 1.75 (s, 3H, COCH3), 3.74–4.85 (m, 81H, 16 ꢃ H-2,
15 ꢃ H3, 16 ꢃ H-5, 16 ꢃ PhCH2, CH2@CH–CH2), 4.98–5.43 (m,
33H, 16 ꢃ H-1, 14 ꢃ H-4, H-3, CH2@CH–CH2), 5.51 (s br, 1H, H-4),
5.71 (s br, 1H, H-4), 5.97–6.05 (m, 1H, CH2@CH–CH2), 7.00–8.10
(160H, 32 ꢃ Ph). Selected 13C NMR data (150 MHz, CDCl3): d
15.5–16.3 (16 ꢃ C-6), 92.6–93.3 (15 ꢃ C-1), 96.6 (C-1), 117.6
(CH2@CH–CH2). Anal. Calcd for C325H328O82: C, 70.38; H, 5.96.
Found: C, 70.49; H, 5.91.
ture was decreased to ꢀ40 °C, and TfOH (2.7
lL, 0.03 mmol) was
added. After the stirring for 2 h the reaction was quenched with
a drop of pyridine, the mixture was diluted with CHCl3 and filtered
through a Celite layer. The filtrate was washed with 1 M aq
Na2S2O3 and water, concentrated, and was twice coevaporated
with toluene. Chromatographic purification of the residue (15:1
toluene–EtOAc) produced 21 (179 mg, 69%) as a colorless syrup;
[a
]
D
ꢀ288 (c 1.0, EtOAc). 1H NMR (500 MHz, CDCl3): d 0.56 (d,
4.2.9. Allyl 3-O-acetyl-4-O-benzoyl-2-O-benzyl-a-L-
3H, J5,6 6.4 Hz, H-6), 0.60–0.70 (m, 24H, 8 ꢃ H-6), 0.75, 1.07, 1.17,
(3d, 9H, J5,6 6.5 Hz, 3 ꢃ H-6), 1.74 (s, 3H, COCH3), 3.74–4.83 (m,
61H, 12 ꢃ H-2, 11 ꢃ H3, 12 ꢃ H-5, 12 ꢃ PhCH2, CH2@CH–CH2),
4.96–5.40 (m, 25H, 12 ꢃ H-1, 10 ꢃ H-4, H-3, CH2@CH–CH2), 5.50
(s br, 1H, H-4), 5.70 (s br, 1H, H-4), 5.95–6.04 (m, 1H, CH2@CH–
CH2), 6.96–8.06 (120H, 24 ꢃ Ph). Selected 13C NMR data
(125 MHz, CDCl3): d 15.5–16.3 (12 ꢃ C-6), 92.5–93.3 (11 ꢃ C-1),
96.5 (C-1), 117.8 (CH2@CH–CH2). Anal. Calcd for C245H248O62: C,
70.32; H, 5.97. Found: C, 70.31; H, 6.03.
fucopyranosyl-(1?4)-3-O-benzoyl-2-O-benzyl-
fucopyranosyl-(1?4)-3-O-benzoyl-2-O-benzyl-
fucopyranoside (26)
a
a
-L-
-L-
A
mixture of MS 4 Å (150 mg), acceptor 24 (40 mg,
0.101 mmol), and donor 25 (97 mg, 0.110 mmol) in CH2Cl2 (2 mL)
was stirred for 30 min at room temperature, cooled to ꢀ40 °C,
and then TMSOTf (4.6 lL, 0.024 mmol) was added. The resulting
mixture was stirred at ꢀ40 to ꢀ30 °C until the disappearance of

V. B. Krylov et al. / Carbohydrate Research 346 (2011) 540–550
547
starting 25 (TLC monitoring), quenched with Et3N, diluted with
CHCl3, and filtered through a Celite layer. Column chromatography
of the residue (5:1 petroleum ether–EtOAc) gave 26 (87 mg, 77%)
1H NMR (600 MHz, CD3OD): d 0.91 (t, 3H, J 7.6 Hz, CH2CH2CH3),
1.22 (d, 48H, J 6.3 Hz, H-6I–XVI), 1.60–1.68 (m, 2H, CH2CH2CH3),
3.48–3.55, 3.57–3.64 (2 ꢃ m, 2H, CH2CH2CH3), 3.78–3.83 (m, 2H,
H-2XVI, H-4XVI), 3.88–4.09 (m, 47H, H-2I–XV, H-3I–XVI, H-4I–XV, H-
5I), 4.28–4.39 (m, 15H, H-5II–XVI), 4.90 (d, 1H, J1,2 3.2 Hz, H-1I),
5.06 (d, 1H, J1,2 3.2, H-1XVI), 5.10 (br s, 14H, H-1II–XV). Selected
13C NMR data (150 MHz, D2O): d 16.8 (C-6I–XII), 67.8 (C-2I–XI),
68.1 (C-5I–XI), 69.9 (C-4I–XI), 76.2 (C-3II–XI), 97.0 (C-1II–XI). HRESIMS:
found m/z 1221.4794; calcd for C99H168O65 [M+2Na]2+ 1221.4812.
as a colorless foam; [
a
]
ꢀ168 (c 1.0, EtOAc). 1H NMR (600 MHz,
D
CDCl3): d 0.47 (d, 3H, J5,6 6.3, H-6III), 0.77 (d, 3H, J5,6 6.6 Hz, H-
6II), 1.33 (d, 3H, J5,6 6.6 Hz, H-6I), 1.91 (s, 3H, COCH3), 3.94 (dd,
1H, J1,2 3.3 Hz, J2,3 = 10.6 Hz), 4.04–4.26 (m, 7H, H-2I–II
, –
CH2CH@CH2, H-5I, H-4I–II), 4.28 (q, 2H, J5,6 6.4 Hz, H-5II–III), 4.53–
4.75 (m, 6H, 3 ꢃ PhCH2), 4.88 (d, 1H, J1,2 3.2 Hz, H-1I), 5.03 (d,
1H, J1,2 3.3 Hz, H-1II), 5.10 (d, 1H, J1,2 3.3 Hz, H-1III), 5.23, 5.36
(2d, 2H, J 10.5 Hz, J 16.8 Hz,, –CH2CH@CH2), 5.43 (s br, 1H, H-4III),
5.46 (dd, 1H, J2,3 10.8 Hz, J3,4 2.9 Hz, H-3III), 5.55–5.61 (m, 2H, H-
3I–II), 5.92–6.00 (m, 1H, –CH2CH@CH2), 7.15–8.10 (m, 30H, 6Ph).
Anal. Calcd for C65H68O17: C, 69.63; H, 6.11. Found: C, 69.41; H,
5.97.
4.3.3. Propyl
a-L-fucopyranosyl-(1?4)-a-L-fucopyranosyl-
(1?4)- -fucopyranoside (10a)
a
-L
A mixture of trifucoside 26 (75 mg, 0.067 mmol) and the cata-
lyst 10% Pd/C (37 mg) in MeOH–EtOAc (3:1) (4 mL) was stirred un-
der H2 (1 atm) at rt for 5 h and then filtered through a Celite layer.
The catalyst was carefully washed with MeOH and the combined
filtrates were concentrated. The residue was dissolved in MeOH
(1 mL) and treated with 1 M aq NaOH (1 mL) for 24 h. Deprotected
trisaccharide was isolated from the reaction mixture by column
chromatography on a gel Sephadex G-15 (60 ꢃ 3 cm) with water
elution followed by lyophilization to give 10a (25 mg, 75%) as a
4.3. Preparation of unprotected oligofucosides 5a, 6a, and 10a
4.3.1. Propyl
a-
L
-fucopyranosyl-(1?3)-a-L-fucopyranosyl-
(1?3)- -fucopyranosyl-(1?3)-
a
-
L
a-
L-fucopyranosyl-(1?3)-a-L-
fucopyranosyl-(1?3)-
fucopyranosyl-(1?3)-
fucopyranosyl-(1?3)-
fucopyranosyl-(1?3)-
a-
a-
a-
a-
L
L
L
L
-fucopyranosyl-(1?3)-
-fucopyranosyl-(1?3)-
-fucopyranosyl-(1?3)-
-fucopyranoside (5a)
a
a
a
-L
-L
-L
-
-
-
white amorphous powder; [
a]
ꢀ131 (c 1.0, H2O). 1H NMR
D
(600 MHz, D2O): d 0.93 (t, 3H, J 7.4 Hz, CH2CH2CH3), 1.19 (d, 3H,
J5,6 6.6 Hz, H-6III), 1.27 (d, 3H, J5,6 6.7 Hz, H-6II), 1.32 (d, 3H, J5,6
6.7 Hz, H-6I), 1.60–1.67 (m, 2H, CH2CH2CH3), 3.49–3.53, 3.63–
3.68 (2 m, 2H, CH2CH2CH3), 3.80–3.88 (m, 6H, H-2I–III, H-4I–III),
3.92–3.98 (m, 2H, H-3I,III), 4.03 (dd, 1H, J2,3 10.3 Hz, J3,4 3.2 Hz, H-
3II), 4.14 (q, 1H, J5,6 6.6 Hz, H-5I), 4.51–4.58 (m, 2H, H-5II–III), 4.94
(d, 1H, J1,2 4.0 Hz, H-1I), 4.97 (d, 1H, J1,2 4.0 Hz, H-1II), 5.00 (d, 1H,
J1,2 4.0 Hz, H-1III). 13C NMR (150 MHz, D2O): d 11.3 (CH2CH2CH3),
16.7 (C-6I–III), 23.6 (CH2CH2CH3), 68.4, 68.5, 69.1 (C-5I–III), 69.6
(H-2II), 70.2, 70.4, 70.6, 70.9 (C-3I–III, H-2I,III), 71.8 (CH2CH2CH3),
73.45 (C-4III), 81.6, 81.7 (C-4I–II), 99.83 (C-1I), 101.9, 102.0 (C-1II–
III). HRESIMS: found m/z 521.2186; calcd for C21H38O13 [M+Na]+
521.2205.
To a soln of oligofucoside 21 (66 mg, 0.016 mmol) in (1:3:0.1)
THF–EtOH–AcOH (3 mL) Pd/C (10%, 40 mg) was added. The mix-
ture was stirred under H2 (1 atm) at rt for 5 h and then filtered
through a Celite layer. The catalyst was carefully washed with
MeOH–CH2Cl2, and the combined filtrates were concentrated.
The residue was dissolved in
a mixture CH2Cl2–EtOH (1:5)
(1.5 mL) and treated with 2 M aq NaOH (0.7 mL) for 12 h at
60 °C. The oligosaccharide products were isolated from the reac-
tion mixture by column chromatography on a gel Sephadex G-15
(60 ꢃ 3 cm) with water elution. Freeze-drying of the oligosaccha-
ride fraction, dissolution of the residue in MeOH–AcOH (20:1),
and stirring of the mixture under H2 (1 atm) in the presence of
10% Pd/C (10 mg) for 5 h led to the complete deprotection of 21.
Separation of the mixture from Pd/C by filtration, concentration
of the solution, column chromatography of the residue on a gel
Sephadex G-15 (60 ꢃ 3 cm) with water elution, and further lyoph-
4.4. Preparation of per-O-sulfated oligofucosides 1b–12b and
28–30
ilization gave 5a (18 mg, 61%) as a white amorphous powder; [a]
D
4.4.1. General procedure of acid-promoted O-sulfation
ꢀ143 (c 1.0, H2O). 1H NMR (600 MHz, D2O): d 0.93 (t, 3H, J 7.3 Hz,
CH2CH2CH3), 1,24 (d, 36H, J5,6 6.2 Hz, H-6I–XII), 1.60–1.69 (m, 2H,
CH2CH2CH3), 3.50–3.56, 3.59–3.65 (2 ꢃ m, 2H, CH2CH2CH3), 3.79–
To a vigorously stirred soln of oligosaccharide (10 mg) in anhyd
DMF (1 mL) the complex Et3NꢁSO3 (5 equiv per OH group) was
added followed by the introduction of an appropriate promoting
acid (0.5–2 equiv per OH group) at 0 °C. The mixture was stirred
until the reaction was completed (TLC monitoring), and then an ex-
cess of 1 M aq NaOH was added. The aqueous phase was washed
with CH2Cl2 (2 ꢃ 1 mL), then loaded onto a Sephadex G-15 column
(60 ꢃ 3 cm), and eluted with water; the fraction containing the
product was collected and freeze-dried to give the per-O-sulfated
oligosaccharide as an amorphous substance.
3.85 (m, 2H, H-2XII, H-4XII), 3.91–4.14 (m, 35H, H-2I–XI, H-3I–XII
,
H-4I–XI, H-5I), 4.30–4.42 (m, 11H, H-5II–XII), 4.93 (d, 1H, J1,2
3.6 Hz, H-1I), 5.08 (d, 1H, J1,2 3.8, H-1XII), 5.12 (br s, 10H, H-1II–XI).
13C NMR (150 MHz, D2O): d 11.3 (CH2CH2CH3), 16.8 (C-6I–XII),
23.6 (CH2CH2CH3), 67.9 (C-2I–XI), 68.1 (C-5I–XI), 68.4 (C-5XII), 69.5
(C-2XII), 70.0 (C-4I–XI), 71.0 (C-3XII), 71.7 (CH2CH2CH3), 73.4 (C-
4XII), 75.9 (C-3I), 76.4 (C-3II–XI), 96.5 (C-1I), 97.0 (C-1II–XI), 99.7 (C-
1XII). HRESIMS: found m/z 929.3672; calcd for C75H128O49
[M+2Na]2+ 929.3654.
4.4.2. Propyl 2,3,4-tri-O-sulfonato-
2,4-di-O-sulfonato- -fucopyranoside pentasodium salt (1b)
Per-O-sulfation of 1a (10 mg, 0.028 mmol) promoted with TfOH
a-L-fucopyranosyl-(1?3)-
a
-L
4.3.2. Propyl
a-
L
-fucopyranosyl-(1?3)-a-L-fucopyranosyl-
(12
lL, 0.14 mmol, 1.0 equiv per OH group) during 24 h gave 1b
(1?3)- -fucopyranosyl-(1?3)-
a
-
L
a-
L-fucopyranosyl-(1?3)-a-L-
(18.8 mg, 77%); [
a]
ꢀ106 (c 0.5, H2O). 1H NMR (600 MHz, D2O):
D
fucopyranosyl-(1?3)-
fucopyranosyl-(1?3)-
fucopyranosyl-(1?3)-
fucopyranosyl-(1?3)-
fucopyranosyl-(1?3)-
fucopyranosyl-(1?3)-
a-
a-
a-
a-
a-
a-
L
L
L
L
L
L
-fucopyranosyl-(1?3)-
-fucopyranosyl-(1?3)-
-fucopyranosyl-(1?3)-
-fucopyranosyl-(1?3)-
-fucopyranosyl-(1?3)-
-fucopyranoside (6a)
a
a
a
a
a
-L
-L
-L
-L
-L
-
-
-
-
-
d 0.92 (3H, t, J 7.5 Hz, CH2CH3), 1.26–1.31 (m, 6H, H-6I–II), 1.58–
1.67 (m, 2H, CH2CH3), 3.53–3.59 (m, 1H, O–CHH0-Et), 3.60–3.67
(m, 1H, O–CHH0-Et), 4.20 (q, 1H, J5,6 6.6 Hz, H-5I), 4.29 (dd, 1H,
J2,3 10.4 Hz, J
2.6 Hz, H-3I), 4.46 (q, 1H, J5,6 6.4 Hz, H-5II), 4.57
3,4
(m, 2H, H-2I–II), 4.91–4.96 (m, 3H, H-4I–II, H-3II), 5.23 (d, 1H,
J1,2 = 3.6 Hz, H-1I), 5.39 (d, 1H, J1,2 = 3.4 Hz, H-1II). 13C NMR
(150 MHz, D2O): d 11.3 (CH2CH3) 17.2 (C-6II), 17.3 (C-6I), 23.3
(CH2CH3), 68.0 (C-5I), 68,6 (C-5II), 71.8 (O–CH2–Et), 73.8 (C-3II),
Deprotection of hexadecasaccharide 23 (62 mg, 0.011 mmol) as
described for the preparation of compound 5a gave hexadecasac-
charide 6a (14 mg, 54%); [
a]
ꢀ157 (c 1.0, H2O).
D

548
V. B. Krylov et al. / Carbohydrate Research 346 (2011) 540–550
74.8 (C-2II), 75.5 (C-3I), 76.0 (C-2I), 80.9 (C-4II), 81.4 (C-4I), 97.6 (C-
4.4.6. Propyl 2,3,4-tri-O-sulfonato-
2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-sulfonato-
fucopyranosyl-(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-
(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-sulfonato-
fucopyranosyl-(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-
(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-sulfonato-
fucopyranoside sodium salt (5b)
Per-O-sulfation of 5a (10 mg, 0.0055 mmol) promoted with TFA
a-L-fucopyranosyl-(1?3)-
1I), 99.1 (C-1II). HRESIMS: found m/z 884.8561; calcd for
a-L
C
15H23Na5O24S5 [M+Na]+ 884.8563.
a
-
L
a-L-
a
-L
a
-L
4.4.3. Propyl 2,3,4-tri-O-sulfonato-
2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-sulfonato-
fucopyranoside nonasodium salt (2b)
Per-O-sulfation of 2a (10 mg, 0.016 mmol) promoted with TFA
a-L-fucopyranosyl-(1?3)-
a-
L
a-L-
a
-L
a
-L
a
-L
a-L-
a-L
a-
L
a-L-
(5.3
lL, 0.072 mmol, 0.5 equiv per OH group) during 24 h gave 2b
(17.6 mg, 75%); [
a]
ꢀ107 (c 1.0, H2O). 1H NMR (500 MHz, D2O):
D
(5.1
lL, 0.069 mmol, 0.5 equiv per OH group) during 24 h gave 5b
(17.3 mg, 72%); [
a
]
D
ꢀ116 (c 1.0, H2O). 1H NMR (600 MHz, D2O):
0.94 (t, 3H, J 7.4 Hz, CH2CH2CH3), 1.29–1.35 (m, 12H, 12 H-6),
1.57–1.66 (m, 2H, CH2CH2CH3), 3.52–3.58 (m, 1H, OCHH0), 3.60–
3.67 (m, 1H, OCHH0), 4,22 (q, 1H, H-5I, J5,6 6.7 Hz), 4.30–4.47 (m,
5H, H-3I–III, H-5II–III), 4.51–4.61 (m, 5H, H-2I–IV, H-5IV), 4.89–4.97
(m, 5H, H-4I–IV, H-3IV), 5.21 (d, 1H, J1,2 3.4 Hz, H-1I), 5.42 (s br,
3H, H-1II–IV). 13C NMR (125 MHz, D2O): d 11.3 (CH2CH3), 17.0,
17.3 (C-6I–IV), 23.3 (CH2CH3), 68,2, 68.3, 68.8 (C-5I–IV), 71.9 (O–
CH2–Et), 73.8, 74.0, 75.2, 76.1, 76.2 (C-3I–IV, C-2I–IV), 81.2, 81.5 (C-
4I–IV), 97.4 (C-1I), 98.7, 99.6 (C-1II–IV). HRESIMS: found m/z
757.8796; calcd for C27H39Na9O44S9 [Mꢀ2Na]2ꢀ 757.8798.
d 0.93 (t, 3H, J 7.4 Hz, CH2CH3), 1.27–1.44 (m, 36H, H-6I–XII),
1.60–1.69 (m, 2H, CH2CH3), 3.54–3.59 (m, 1H, O-CHH0-Et), 3.61–
3.67 (m, 1H, O–CHH0-Et), 4.22 (q, 1H, J5,6 6.7, H-5I), 4.28–4.45 (m,
21H, H-3I–XI, H-5II–XI), 4.47–4.56 (m, 13H, H-2I–XII, H-5XII), 4.88–
4.96 (m, 13H, H-4I–XII, H-3XII), 5.24 (d, 1H, J1,2 3.3 Hz, H-1I), 5.41
(s br, 11H, H-1II–XII). Selected 13C NMR data (150 MHz, CDCl3):
17.2 (C-6I–XVI), 68.3, (C-5I–XVI), 75.5 76.3, (C-3I–XV, C-2I–XVI), 81.2,
82.1 (C-4I–XVI), 97.4 (C-1I), 100.0, 98.8 (C-1II–XVI).
4.4.7. Propyl 2,3,4-tri-O-sulfonato-
2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-sulfonato-
fucopyranosyl-(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-
(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-sulfonato-
fucopyranosyl-(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-
(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-sulfonato-
fucopyranosyl-(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-
(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-sulfonato-
fucopyranoside sodium salt (6b)
Per-O-sulfation of 6a (10 mg, 0.0042 mmol) promoted with TFA
a-L-fucopyranosyl-(1?3)-
4.4.4. Propyl 2,3,4-tri-O-sulfonato-
2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-sulfonato-
fucopyranosyl-(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-
-fucopyranoside tridecasodium
a-L-fucopyranosyl-(1?3)-
a
-L
a
-L
a-
L
a-L-
a
-L
a-L-
a
-L
a-L
a-L
(1?3)-2,4-di-O-sulfonato-a-L
a-
L
a-L-
salt (3b)
a
-L
Per-O-sulfation of 3a (10 mg, 0.011 mmol) promoted with TFA
a-L
(5.3
lL, 0.72 mmol, 0.5 equiv per OH group) during 24 h gave 3b
a-
L
a-L-
(18.3 mg, 76%); [
a]
ꢀ89 (c 1.0, H2O). 1H NMR (600 MHz, D2O): d
D
a
-L
0.93 (t, 3H, J 7.5 Hz, CH2CH3), 1.29–1.38 (m, 18H, H-6I–VI), 1.60–
1.70 (m, 2H, CH2CH3), 3.52–3.59 (m, 1H, O–CHH0-Et), 3.60–3.67
(m, 1H, O–CHH0-Et), 4.22 (q, 1H, J5,6 6.7 Hz, H-5I), 4.29–4.46 (m,
9H, H-3I–V, H-5II–V), 4.47–4.57 (m, 7H, H-2I–VI, H-5VI), 4.89–4.96
(m, 7H, H-4I–VI, H-3VI), 5.21 (d, 1H, J1,2 3.4 Hz, H-1I), 5.41 (s br,
5H, H-1II–VI). 13C NMR (150 MHz, D2O): d 11.3 (CH2CH3), 17.1,
17.3 (C-6I–VI), 23.3 (CH2CH3), 68,2, 68.3, 68.9 (C-5I–VI), 71.9 (O–
a-L
a-
L
a-L-
(5.1
lL, 0.069 mmol, 0.5 equiv per OH group) during 24 h gave 6b
(18.0 mg, 75%); [
a
]
D
ꢀ108 (c 1.0, H2O). 1H NMR (600 MHz, D2O):
d 0.95 (t, 3H, J 7.6 Hz, CH2CH3), 1.37 (d, 48H, J5,6 6.1 Hz, H-6I–XVI),
1.63–1.70 (m, 2H, CH2CH3), 3.55–3.61 (m, 1H, O–CHH0-Et), 3.62–
3.68 (m, 1H, O–CHH0-Et), 4.24 (m, 1H, H-5I), 4.32–4.48 (m, 29H,
H-3I–XV, H-5II–XV), 4.49–4.59 (m, 17H, H-2I–XVI, H-5XVI), 4.90–4.97
(m, 17H, H-4I–XVI, H-3XVI), 5.26 (d, 1H, J1,2 = 3.5 Hz, H-1I), 5.43 (s
br, 15H, H-1II–XVI). Selected 13C NMR data (150 MHz, D2O): 17.1
(C-6I–XVI), 68.3, (C-5I–XVI), 75.5 76.2, (C-3I–XV, C-2I–XVI), 81.3, 82.1
(C-4I–XVI), 97.4 (C-1I), 100.2, 98.8 (C-1II–XVI).
CH2–Et), 73.8 (C-3VI), 74.1 (C-2VI), 75.2, 75.5, 76.1, 76.2 (C-3I–V
C-2I–V), 81.3, 81.5 (C-4I–VI), 97.4 (C-1I), 98.8, 100.1 (C-1II–VI). HRE-
,
SIMS: found m/z 1153.7926; calcd for
C39H55Na13O64S13
[M+2Na]2+ 1153.7936.
4.4.5. Propyl 2,3,4-tri-O-sulfonato-
2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-sulfonato-
fucopyranosyl-(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-
(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-sulfonato-
fucopyranoside heptadecasodium salt (4b)
Per-O-sulfation of 4a (10 mg, 0.0081 mmol) promoted with TFA
a-L-fucopyranosyl-(1?3)-
a
-L
a
-L
a-L-
a-L
4.4.8. Propyl 2,3,4-tri-O-sulfonato-
2,3-di-O-sulfonato- -fucopyranoside pentasodium salt (7b)
Per-O-sulfation of 7a (10 mg, 0.028 mmol) promoted with TfOH
a-L-fucopyranosyl-(1?4)-
a
-L
a
-L
a
-L
a-L-
(12.4
(20.3 mg, 83%); [
lL, 0.14 mmol 1.0 equiv per OH group) during 24 h gave 7b
a
]
D
ꢀ96 (c 1.0, H2O). 1H NMR (600 MHz, D2O): d
0.97 (t, 3H, J 7.5 Hz, –CH2CH2CH3), 1.35 (d, 3H, J5,6 6.5 Hz, H-6II),
1.42 (d, 3H, J5,6 6.6 Hz, H-6I), 1.63–1.71 (m, 2H, CH2CH2CH3),
3.58–3.64, 3.68–3.73 (2 ꢃ m, 2H, CH2CH2CH3), 4.24 (q, 1H, J5,6
6.6 Hz, H-5I), 4.32 (br s, 1H, H-5I), 4.57–4.62 (m, 2H, H-2II, H-5II),
4.67 (dd, 1H, J1,2 3.6 Hz, J2,3 10.8 Hz, H-2I), 4.72 (dd, 1H, J3,4
2.3 Hz, J2,3 10.8 Hz, H-3I), 4.86 (dd, 1H,, J3,4 2.6 Hz, J2,3 10.7 Hz, H-
3II), 5.01 (d, 1H, J3,4 2.6 Hz, H-4II), 5.28 (d, 1H, J1,2 3.6 Hz, H-1I),
5.35 (d, 1H, J1,2 3.4 Hz, H-1II). 13C NMR (150 MHz, D2O): d 11.4 (–
CH2CH2CH3), 17.0 (C-6I), 17.3 (C-6II), 23.4 (–CH2CH2CH3), 68.5 (C-
5II), 68.7 (C-5I), 71.9 (–CH2CH2CH3), 73.8 (C-3II), 74.0 (C-2I), 74.2
(C-2II), 75.5 (C-3I), 81.2 (C-4I–II), 97.9 (C-1I), 100.3 (C-1II). HRESIMS:
found m/z 884.8569; calcd for C15H23Na5O24S5 [M+Na]+ 884.8563;
found m/z 838.8760; calcd for [MꢀNa]– 838.8779.
(5.1
lL, 0.069 mmol, 0.5 equiv per OH group) during 24 h gave 4b
(18.8 mg, 78%). [
a
]
D
ꢀ84 (c 1.0, H2O). 1H NMR (600 MHz, D2O): d
0.96 (t, 3H, J 7.6 Hz, CH2CH3), 1.32–1.40 (m, 24H, H-6I–VI), 1.61–
1.71 (m, 2H, CH2CH3), 3.54–3.61 (m, 1H, O–CHH0-Et), 3.62–3.69
(m, 1H, O–CHH0-Et), 4.25 (q, 1H, J5,6 6.7 Hz, H-5I), 4.32–4.48 (m,
13H, H-3I–VII, H-5II–VII), 4.50–4.60 (m, 9H, H-2I–VIII, H-5VIII), 4.92–
4.99 (m, 9H, H-4I–VIII, H-3VIII), 5.25 (d, 1H, J1,2 3.5 Hz, H-1I), 5.44
(s br, 7H, H-1II–VIII). 13C NMR (150 MHz, D2O): d 11.4 (CH2CH3).
17.1, 17.3 (C-6I–VIII), 23.4 (CH2CH3), 68.2, 68.4, 69.1 (C-5I–VIII),
71.9 (O–CH2–Et), 73.8 (C-3VIII), 74.1 (C-2VIII), 75.2, 75.7, 76.1, 76.3
(C-3I–VII, C-2I–VII), 81.3, 82.1 (C-4I–VIII), 97.4 (C-1I), 98.8, 100.2 (C-1
II–VIII). HRESIMS: found m/z 964.1730; calcd for C51H71Na17O84S17
[Mꢀ3Na]3ꢀ 964.1707.

V. B. Krylov et al. / Carbohydrate Research 346 (2011) 540–550
549
4.4.9. Propyl 2,3,4-tri-O-sulfonato-
2,3-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?4)-2,3-di-O-sulfonato-
fucopyranoside nonasodium salt (8b)
Per-O-sulfation of 8a (10 mg, 0.016 mmol) promoted with TfOH
a
-
L
-fucopyranosyl-(1?4)-
H-2I–II, H-3I), 4.83–4.87 (m, 2H, H-3II–III), 5.00 (d, 1H, J3,4 3.0 Hz,
H-4III), 5.28 (d, 1H, J1,2 3.5 Hz, H-1I), 5.33 (d, 1H, J1,2 3.5 Hz, H-
1III), 5.37 (d, 1H, J1,2 3.5 Hz, H-1II). 13C NMR (150 MHz, D2O): d
11.3 (CH2CH2CH3), 17.0, 17.3 (C-6I–III), 23.4 (CH2CH2CH3), 68.5,
68.8, 69.8 (C-5I–III), 71.9 (CH2CH2CH3), 73.8 (C-3III), 74.0, 74.2,
74.3 (C-2I–III), 75.1 (C-3II), 75.5 (C-3I), 80.6 (C-4I), 81.4 (C-4III),
81.7 (C-4II), 97.9 (C-1I), 100.3 (C-1II–III). HRESIMS: found m/z
582.9116; calcd for C21H31Na7O34S7 [Mꢀ2Na]2ꢀ 582.9116.
a-L
a
-L
a-L-
(12.8
(19.7 mg, 84%); [
lL, 0.14 mmol, 1.0 equiv per OH group) during 24 h gave 8b
a]
ꢀ107 (c 1.0, H2O). 1H NMR (600 MHz, D2O):
D
0.95 (t, 3H, J 7.4 Hz, CH2CH2CH3), 1.34–1.42 (m, 12H, H-6I–IV),
1.61–1.70 (m, 2H, CH2CH2CH3), 3.57–3.61, 3.66–3.71 (2 ꢃ m, 2H,
CH2CH2CH3), 4.23 (q, 1H, J5,6 6.7 Hz, H-5I), 4.31 (br s, 2H, H-4I,III),
4.40 (dd, 1H, J2,3 10.7 Hz, J3,4 2.2 Hz, H-3II), 4.44 (q, 1H, J5,6 6.4 Hz,
H-5), 4.53 (q, 1H, J5,6 6.5 Hz, H-5), 4.56–4.64 (m, 4H, H-2I–II, IV, H-
5), 4.68 (dd, 1H, J2,3 10.7 Hz, J3,4 2.2 Hz, H-3I), 4.72 (dd, 1H, J1,2
3.4 Hz, J2,3 10.8 Hz, H-2III), 4.85 (dd, 1H, J2,3 10.7 Hz, J3,4 2.8 Hz, H-
3IV), 4.92 (dd, 1H, J2,3 2.4 Hz, J3,4 10.7 Hz, H-3III), 4.96 (d, 1H, J3,4
2.2 Hz, H-4II), 4.99 (d, 1H, J3,4 2.4 Hz, H-4IV), 5.25 (d, 1H, J1,2
3.8 Hz, H-1I), 5.32 (d, 1H, J1,2 3.4 Hz, H-1IV), 5.38 (d, 1H, J1,2
3.4 Hz, H-1II), 5.46 (d, 1H, J1,2 3.4 Hz, H-1III). 13C NMR (150 MHz,
D2O): d 11.4 (–CH2CH2CH3), 17.0, 17.2, 17.3, 17.5 (C-6I–IV), 23.4 (–
CH2CH2CH3), 68.4, 68.8, 69.0, 69.4 (C-5I–IV), 71.9 (–CH2CH2CH3),
73.2 (C-3II), 73.9 (C-3IV, C-2III), 74.1, 74.2 (C-2I,IV), 74.9 (C-3III),
75.3 (C-2II), 75.8 (C-3I), 80.9 (C-4II), 81.3, 81.4 (C-4I,III–IV), 97.5 (C-
1III), 97.9 (C-1I), 100.2 (C-1IV), 100.4 (C-1II). HRESIMS: found m/z
757.8817; calcd for C27H39Na9O44S9 [Mꢀ2Na]2ꢀ 757.8798.
4.4.12. Propyl 2,3,4-tri-O-sulfonato-
3,4-di-O-sulfonato- -fucopyranoside pentasodium salt (11b)
Per-O-sulfation of 11a (8 mg, 0.022 mmol) promoted with TfOH
a-L-fucopyranosyl-(1?2)-
a
-L
(9.8 lL, 0.11 mmol, 1.0 equiv per OH group) during 24 h gave 11b
(14.1 mg, 72%); [
a
]
ꢀ104 (c 1.0, H2O). 1H and 13C NMR spectra
D
coincided with the previously reported ones.12 HRESIMS: found
m/z 407.9443; calcd for C15H23Na5O24S5 [Mꢀ2Na]2ꢀ 407.9443.
4.4.13. Propyl 2,3,4-tri-O-sulfonato-
a-
D-glucopyranosyl uronic
acid-(1?2)-2,3-di-O-sulfonato-a-L-fucopyranoside hexasodium
salt (12b)
Per-O-sulfation of 12a (7.3 mg, 0.018 mmol) promoted with
TfOH (8.0
12b (14.0 mg, 85%); [
lL, 0.09 mmol, 1.0 equiv per OH group) during 24 h gave
a
]
D ꢀ14 (c 1.0, H2O). 1H NMR (600 MHz, D2O):
d 0.96 (t, 3H, J 7.5 Hz, –CH2CH2CH3), 1.30 (d, 3H, J5,6 6.5 Hz, H-6I),
1.65–1.72 (m, 2H, –CH2CH2CH3), 3.60–3.68 (m, 2H, –CH2CH2CH3),
3.21 (dd, 1H, J1,2 3.8 Hz, J2,3 10.6 Hz, H-2I), 4.25 (q, 1H, J5,6 6.5 Hz,
H-5I), 4.41 (d, 1H, J4,5 5.5 Hz, H-5II), 4.54 (dd, 1H, J1,2 2.3 Hz, J2,3
6.5 Hz, H-2II), 4.73–4.78 (m, 2H, H-3I, H-4II), 4.94–4.98 (m, 2H, H-
3II, H-4I), 5.09 (d, 1H, J1,2 3.8 Hz, H-1I), 5.45 (d, 1H, J1,2 2.3 Hz, H-
1II). 13C NMR (150 MHz, D2O): d 11.3 (–CH2CH2CH3), 17.1 (C-6I),
23.4 (–CH2CH2CH3), 67.2 (C-5I), 71.9 (CH2CH2CH3), 74.17 (C-2II),
75.3 (C-3II, C-2I), 75.7 (C-3I, C-4II), 76.2 (C-5II), 80.5 (C-4I), 97.8
(C-1II), 99.3 (C-1I). HRESIMS: found m/z 936.8141; calcd for
4.4.10. Propyl 2,3,4-tri-O-sulfonato-
2,3-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl–(1?4)-2,3-di-O-sulfonato-
fucopyranosyl-(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-
-fucopyranoside tridecasodium
a-L-fucopyranosyl-(1?4)-
a-L
a
-L
a-L-
a-L
(1?4)-2,3-di-O-sulfonato-a-L
salt (9b)
Per-O-sulfation of 9a (10 mg, 0.011 mmol) promoted with TfOH
(12.7
(20.0 mg, 83%); [
lL, 0.14 mmol, 1.0 equiv per OH group) during 24 h gave 9b
ꢀ115 (c 1.0, H2O). 1H NMR (600 MHz, D2O):
C
15H20Na6O26S5 [M+Na]+ 936.8125.
a
]
D
0.96 (t, 3H, J 7.5 Hz, CH2CH2CH3), 1.35–1.44 (m, 18H, H-6I–VI),
1.63–1.70 (m, 2H, CH2CH2CH3), 3.57–3.63, 3.67–3.73 (2 ꢃ m, 2H,
CH2CH2CH3), 4.24 (q, 1H, J5,6 6.7 Hz, H-5I), 4.31–4.34 (m, 3H, H-
4I,III,V), 4.38–4.41 (m, 2H, H-3II,IV), 4.44 (q, 1H, J5,6 6.6 Hz, H-5),
4.49–4.56 (m, 3H, 3 ꢃ H-5), 4.58–4.66 (m, 5H, H-2I,II,IV,VI, H-5),
4.67–4.71 (m, 2H, H-3I, H-2III), 4.72–4.75 (m, 1H, H-2V), 4.86 (dd,
1H, J2,3 10.7 Hz, J3,4 3.0 Hz, H-3VI), 4.91–4.95 (m, 2H, H-3III,V),
4.97–5.01 (3 ꢃ d, 3H, J3,4 2.5 Hz, H-4II,IV,VI), 5.27 (d, 1H, J1,2 3.7 Hz,
H-1I), 5.34 (d, 1H, J1,2 = 3.6 Hz, H-1VI), 5.39, 5.43 (2 ꢃ d, 2H, J1,2
3.6 Hz, H-1II,IV), 5.46, 5.48 (2 ꢃ d, 2H, J1,2 3.4 Hz, H-1III,V). 13C
NMR (150 MHz, D2O): d 11.4 (–CH2CH2CH3), 17.0, 17.3, 17.5 (C-6
I–VI), 23.4 (–CH2CH2CH3), 68.4, 68.8, 68.9, 69.0, 69.5 (C-5I–VI), 71.9
4.4.14. Propyl 2,3,4-tri-O-sulfonato-
2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,5-di-O-sulfonato-
fucofuranoside nonasodium salt (28)
Per-O-sulfation of 2a (10 mg, 0.016 mmol) promoted with TfOH
a-L-fucopyranosyl-(1?3)-
a
-L
a-
L
a-L-
(25.6
(16.7 mg, 71%); [
lL, 0.29 mmol, 2.0 equiv per OH group) during 48 h gave 28
a
]
D
ꢀ126 (c 1.0, H2O). 1H NMR (500 MHz, D2O):
d 0.91 (t, 3H, J 7.5 Hz, CH2CH3), 1.32–1.40 (m, 9H, H-6II–IV), 1.45
(d, 3H, J5,6 6.4 Hz, H-6I), 1.58–1.67 (m, 2H, CH2CH3), 3.43–3.50
(m, 1H, O–CHH0-Et), 3.77–3.85 (m, 1H, O–CHH0-Et), 4.02 (t, 1H,
J3,4 J4,5 6.0 Hz, H-4I), 4.28 (dd, 1H, J2,3 10.4 Hz, J3,4 2.5 Hz, H-3II),
(–CH2CH2CH3), 73.2 (C-3II), 73.9, 74.0, 74.1 (C-2I,III,V,VI, C-3IV,VI
)
4.34–4.42 (m, 4H, H-3I,III, H-5II,III), 4.50–4.61 (m, 4H, H-2II–IV
,
74.9, 75.1 (C-3III,V), 75.4, 75.5 (C-2II,IV), 75.9 (C-3I), 80.9 (C-4II),
81.4, 81.5 (C-4I,III–VI), 97.5 (C-1III), 97.9 (C-1I), 98.2 (C-1V), 100.1
(C-1VI), 100.2, 100.3 (C-1II,IV). HRESIMS: found m/z 730.8823; calcd
for C39H55Na13O64S13 [Mꢀ3Na]3ꢀ 730.8804.
H-5IV), 4.61–4.65(m, 1H, H-5I), 4.77 (dd, 1H, J1,2 4.4 Hz, J2,3
7.3 Hz, H-2I), 4.87–4.95 (m, 6H, H-4II–IV, H-3IV), 5.23 (d, 1H, J1,2
4.4 Hz, H-1I), 5.39–5.44 (m, 3H, H-1II–IV). 13C NMR (125 MHz,
D2O): d11.2 (CH2CH3); 17.2, 17.5 (C-6II–IV), 18.0 (C-6I), 23.3
(CH2CH3), 68.1 (C-5II), 68.7, 69.1 (C-5III–IV), 71.8 (O–CH2–Et), 73.8
(C-3IV), 73.9 (C-2IV), 75,2, 75.5, 75.6, 75,7 (C-2II,III, C-3II,III), 78.6
(H-5I), 81.2 (C-3I), 81.3, 81.5, 81.6 (C-4II–VI), 83.9 (C-4I), 98.4, 99.5
(C-1II–IV), 101.2 (C-1I). HRESIMS: found m/z 757.8783; calcd for
4.4.11. Propyl 2,3,4-tri-O-sulfonato-
2,3-di-O-sulfonato- -fucopyranosyl-(1?4)-2,3-di-O-
sulfonato- -fucopyranoside heptasodium salt (10b)
Per-O-sulfation of 10a (10 mg, 0.020 mmol) promoted with
a-L-fucopyranosyl-(1?4)-
a-L
C
27H39Na9O44S9 [Mꢀ2Na]2ꢀ 757.8798.
a
-L
TfOH (12.4
gave 10b (17.9 mg, 75%);
lL, 0.14 mmol, 1.0 equiv per OH group) during 24 h
4.4.15. Propyl 2,3,4-tri-O-sulfonato-
2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-sulfonato-aa
fucopyranosyl-(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-
-fucofuranoside tridecasodium
a-L-fucopyranosyl-(1?3)-
[a
]
D
ꢀ102 (c 1.0, H2O). 1H NMR
a
-L
(600 MHz, D2O): d 0.97 (t, 3H, J 7.5 Hz, CH2CH2CH3), 1.37 (d, 3H,
J5,6 6.5 Hz, H-6), 1.42 (d, 3H, J5,6 6.6 Hz, H-6), 1.46 (d, 3H, J5,6
6.7 Hz, H-6), 1.64–1.71 (m, 2H, CH2CH2CH3), 3.58–3.63, 3.67–3.73
(2 ꢃ m, 2H, CH2CH2CH3), 4.23 (q, 1H, J5,6 6.7 Hz, H-5), 4.32 (d, 1H,
J3,4 2.4 Hz, H-4I), 4.34 (d, 1H, J3,4 2.5 Hz, H-4II), 4.54 (q, 1H, J5,6
6.6 Hz, H-5), 4.58–4.63 (m, 2H, H-5, H-2III), 4.66–4.72 (m, 3H,
a-
L
-L-
a
-L
(1?3)-2,5-di-O-sulfonato-a-L
salt (29)
Per-O-sulfation of 3a (10 mg, 0.011 mmol) promoted with TfOH
(25.4 L, 0.29 mmol, 2.0 equiv per OH group) during 48 h gave 29
l

550
V. B. Krylov et al. / Carbohydrate Research 346 (2011) 540–550
(17.8 mg, 74%); [
a]
D ꢀ138 (c 0.5, H2O). 1H NMR (500 MHz, D2O): d
References
0.93 (t, 3H, J 7.4 Hz, CH2CH3), 1.30–1.38 (m, 15H, H-6II–VI), 1.45 (d,
3H, J5,6 6.4 Hz, H-6I), 1.58–1.67 (m, 2H, CH2CH3), 3.44–3.51 (m, 1H,
O–CHH0-Et), 3.77–3.86 (m, 1H, O–CHH0-Et), 4.02 (t, 1H, J3,4 J4,5
6.0 Hz, H-4I), 4.26 (dd, 1H, J2,3 10.4 Hz, J3,4 2.5 Hz, H-3II), 4.34–
4.46 (m, 8H, H-3I,III–V, H-5II–V), 4.48–4.58 (m, 6H, H-2II–VI, H-5VI),
4.58–4.65 (m, 1H, H-5I), 4.77 (dd, 1H, J1,2 4.4 Hz, J2,3 7.3 Hz, H-2I),
4.90–4.97 (m, 6H, H-4II–VI, H-3VI), 5.23 (d, 1H, J1,2 4.4 Hz, H-1I),
5.39–5.44 (m, 5H, H-1II–VI). 13C NMR (125 MHz, D2O): d 11.2
(CH2CH3); 17.3 (C-6II–VI), 18.0 (C-6I), 23.3 (CH2CH3), 68.2 (C-5II),
68.8, 69.0, 69.3 (C-5III–VI), 71.8 (O–CH2–Et), 73.8 (C-3VI), 74.0 (C-
2VI), 75.5, 75.7, 75.9 (C-3III–V, C-2II–V), 76.6 (H-3II), 78.6 (H-5I),
81.2 (C-3I), 81.9, 81.5, 81.3 (C-4II–VI), 83.9 (C-4I), 100.3, 98.8, 98.4
(C-1II–VI), 101.3 (C-1I). HRESIMS: found m/z 1107.8149; calcd for
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Totani, L.; Tinari, N.; Morozevich, G. E.; Berman, A. E.; Bilan, M. I.; Usov, A. I.;
Ustyuzhanina, N. E.; Grachev, A. A.; Sanderson, C. J.; Kelly, M.; Rabinovich, G. A.;
Iacobelli, S.; Nifantiev, N. E. Glycobiology 2007, 17, 541–552.
4. Pomin, V. Biopolymers 2009, 91, 601–609.
5. Berteau, O.; Mulloy, B. Glycobiology 2003, 13, 29R–40R.
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7. Ustyuzhanina, N.; Krylov, V.; Grachev, A.; Gerbst, A.; Nifantiev, N. Synthesis
2006, 23, 4017–4031.
8. Khatuntseva, E. A.; Ustuzhanina, N. E.; Zatonskii, G. V.; Shashkov, A. S.; Usov, A.
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9. Gerbst, A. G.; Ustuzhanina, N. E.; Grachev, A. A.; Tsvetkov, D. E.; Khatuntseva, E.
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821–831.
C
39H55Na13O64S13 [Mꢀ2Na]2ꢀ 1107.8152.
10. Gerbst, A. G.; Ustuzhanina, N. E.; Grachev, A. A.; Tsvetkov, D. E.; Khatuntseva, E.
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D. E.; Usov, A. I.; Shashkov, A. S.; Preobrazhenskaya, M. E.; Ushakova, N. A.;
Nifantiev, N. E. Russ. J. Bioorg. Chem. 2004, 30, 137–147.
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4.4.16. Propyl 2,3,4-tri-O-sulfonato-
2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-sulfonato-
fucopyranosyl-(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-
(1?3)-2,4-di-O-sulfonato- -fucopyranosyl-(1?3)-2,4-di-O-
sulfonato- -fucopyranosyl-(1?3)-2,5-di-O-sulfonato-
fucofuranoside heptadecasodium salt (30)
Per-O-sulfation of 4a (10 mg, 0.0081 mmol) promoted with
a-L-fucopyranosyl-(1?3)-
a
-L
a
-
L
a-L-
a-L
a
-L
a
-L
a-L-
14. Grachev, A. A.; Gerbst, A. G.; Ustuzhanina, N. E.; Khatuntseva, E. A.; Shashkov,
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Nifantiev, N. E. J. Carbohydr. Chem. 2006, 25, 315–330.
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Usov, A. I.; Nifantiev, N. E. Mendeleev Commun. 2007, 17, 57–62.
17. Nishino, T.; Nagumo, T. Carbohydr. Res. 1992, 229, 355–362.
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TfOH (24.4
gave 30 (16.6 mg, 69%);
lL, 0.28 mmol, 2.0 equiv per OH group) during 48 h
[a
]
D
ꢀ121 (c 1.0, H2O). 1H NMR
(500 MHz, D2O): d 0.93 (t, 3H, J 7.4 Hz, CH2CH3), 1.30–1.40 (m,
21H, H-6II–VIII), 1.45 (d, 3H, J5,6 6.5 Hz, H-6I), 1.58–1.66 (m, 2H,
CH2CH3), 3.43–3.51 (m, 1H, O–CHH0-Et), 3.77–3.87 (m, 1H, O–
CHH0-Et), 4.04 (t, 1H, J3,4 J4,5 5.9 Hz, H-4I), 4.25 (dd, 1H, J2,3
10.3 Hz, J3,4 2.3 Hz, H-3II), 4.30–4.45 (m, 12H, H-3I,III–VII, H-5II–VII),
4.48–4.57 (m, 8H, H-2II–VIII, H-5VIII), 4.57–4.67 (m, 1H, H-5I), 4.78
(dd, 1H, J1,2 4.4 Hz, J2,3 7.3 Hz, H-2I), 4.89–4.96 (m, 8H, H-4II–VIII
,
H-3VIII), 5.23 (d, 1H, J1,2 = 4.4 Hz, H-1I), 5.37–5.43 (m, 7H, H-1II–VIII).
13C NMR (125 MHz, D2O): d 11.2 (CH2CH3), 17.3 (C-6II–VIII), 18.1 (C-
6I), 23.3 (CH2CH3), 68.2 (C-5II), 68.8, 68.9, 69.3 (C-5III–VIII), 71.8 (O–
CH2–Et), 73.8 (C-3VIII), 74.1 (C-2VIII), 75.5, 75.6, 75.9 (C-3III–VII, C-2II–
VII), 76.5 (H-3II), 78.5 (H-5I), 81.1 (C-3I), 81.3, 81.5, 82.0 (C-4II–VI),
83.9 (C-4I), 98.4, 98.6, 100.2 (C-1II–VIII), 101.2 (C-1I). HRESIMS:
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found m/z 1503.7348; calcd for
1503.7291.
C
51H71Na17O84S17 [M+2Na]2+
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This work was supported by the Russian Foundation for Basic
Research (Grant 10-03-00980-a) and a grant from the President
of the Russian Federation to Young Scientists, MR-3901.2009.4
and MR-5544.2010.3. High resolution mass spectra were recorded
in the Department of Structural Studies of Zelinsky Institute of Or-
ganic Chemistry, Moscow.
Supplementary data
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Supplementary data (high resolution mass spectra of non-
protected and sulfated oligofucosides) associated with this article
can be found, in the online version, at doi:10.1016/j.carres.
2011.01.005.