Synthesis of regioselectively sulfated xylodextrins and crystal structure of sodium methyl β-d-xylopyranoside 4-O-sulfate hemihydrate

Article abstract of DOI:10.1016/j.carres.2008.09.018

Methyl xylobioside and methyl xylotrioside were prepared from the peracetylated anomeric xylosyl trichloroacetimidates by reaction with methanol followed by Zemplen deacetylation. Methyl β-d-xylopyranoside, methyl β-d-xylobioside and methyl β-d-xylotrioside were subjected to treatment with dibutyltin oxide followed by reaction with the trimethylamine/sulfur trioxide complex in tetrahydrofuran. This way, preferential sulfation of the terminal 4-hydroxy group at the nonreducing xylopyranosyl unit was achieved. In addition, partial sulfation at position 2 of the distal xylose unit was observed. The substitution pattern was derived from NMR spectroscopic data and was confirmed by the X-ray structure determination of sodium methyl β-d-xylopyranoside 4-O-sulfate. The compound crystallized as a hemihydrate in a triclinic lattice of space group P1 and possesses a pseudomonoclinic 2D supramolecular structure. The sulfation of free pentose oligomers via their intermediate stannylene acetals may thus be exploited to generate biologically active oligosaccharides for biomedical applications.

Full text of DOI:10.1016/j.carres.2008.09.018

Carbohydrate Research 344 (2009) 21–28
Contents lists available at ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Synthesis of regioselectively sulfated xylodextrins and crystal structure
of sodium methyl b-D-xylopyranoside 4-O-sulfate hemihydrate
a
b
c
a
a, ,
*
Beatriz Abad-Romero , Kurt Mereiter , Herbert Sixta , Andreas Hofinger , Paul Kosma
a
Department of Chemistry, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
Department of Chemistry, Vienna University of Technology, Getreidemarkt 9/164SC, A-1060 Vienna, Austria
Lenzing AG, A-4820 Lenzing, Austria
b
c
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 21 August 2008
Received in revised form 9 September 2008
Accepted 10 September 2008
Available online 24 September 2008
Methyl xylobioside and methyl xylotrioside were prepared from the peracetylated anomeric xylosyl
trichloroacetimidates by reaction with methanol followed by Zemplén deacetylation. Methyl b- -xylopy-
ranoside, methyl b- -xylobioside and methyl b- -xylotrioside were subjected to treatment with dibutyl-
tin oxide followed by reaction with the trimethylamine/sulfur trioxide complex in tetrahydrofuran. This
way, preferential sulfation of the terminal 4-hydroxy group at the nonreducing xylopyranosyl unit was
achieved. In addition, partial sulfation at position 2 of the distal xylose unit was observed. The
substitution pattern was derived from NMR spectroscopic data and was confirmed by the X-ray structure
D
D
D
Keywords:
Hemicellulose
Sulfation
determination of sodium methyl b-D-xylopyranoside 4-O-sulfate. The compound crystallized as a hemi-
hydrate in a triclinic lattice of space group P1 and possesses a pseudomonoclinic 2D supramolecular
structure. The sulfation of free pentose oligomers via their intermediate stannylene acetals may thus
be exploited to generate biologically active oligosaccharides for biomedical applications.
Ó 2008 Elsevier Ltd. All rights reserved.
Regioselectivity
Xylodextrin
Crystal structure
1
. Introduction
Low molecular weight xylans have become available in multi-
of the saccharide linkages.7,8 Regioselective derivatization via the
intermediate formation of cyclic stannylene acetals has been inten-
sively studied and used as a versatile method for the specific
installment of protecting groups—mostly for 1,2-cis oriented diol
gram to kg amounts from process eluents in the dissolving pulp
industry and viscose manufacture and may be further converted
into xylodextrins. Since renewable materials merit further exploi-
tation for multiple applications, subsequent conversion of these
xylans into higher-value products via derivatization should be at-
tempted. Among the approaches for polysaccharide derivatiza-
tion, sulfation of oligo- and polysaccharides has attracted
considerable interest for the development of antithrombotic drugs
and as advanced materials for biomedical applications. As exam-
ples, regioselectively sulfated cellulose-obtained via protecting
group manipulation- has been utilized as inhibitor of adhesion of
Plasmodium falciparum, while polysulfated b-(1?4)-linked xylans
showed inhibitory activity against human immunodeficiency
9
systems in oligosaccharide synthesis. For xylopyranosides, acyla-
1
tion as well as silylation of stannylene derivatives have been re-
ported to give preferential substitution at O-4 of
1
0–13
xylopyranosides.
While a large body of these studies has been
2
performed in the field of oligosaccharide synthesis, little effort has
been invested in comparable reactions on polysaccharides. In a
first approach, we describe herein the regioselective introduction
of sulfate groups into xylopyranosyl mono-, di- and trisaccharide
model compounds complemented by the crystal structure deter-
mination of the 4-O-monosulfate of methyl b-D-xylopyranoside.
Biological data of the sulfated compounds and extension of this ap-
proach towards higher xylodextrins will be published in due
course.
3
,4
virus-1, respectively.
xylans have been synthesized using the DMF/SO
were shown to have antithrombin activity. Sulfated di- and trisac-
charides have also been developed as antiasthmatic agents. Com-
Regioselectively sulfated b-(1?3)-linked
complex and
3
5
2. Results and discussion
6
mon sulfation has mainly been effected using chlorosulfonic acid,
2.1. Preparation of methyl glycosides of xylooligomers
3 2 4 3
DMF/SO , N O /SO , and related agents, which often lead to fully
or randomly sulfated polysaccharides with concomitant hydrolysis
As defined model compounds of sulfated xylodextrins, methyl
glycosides 10 and 12 were synthesized similar to recently
1
4
published procedures.
Thus, a degraded beech wood xylan
*
Corresponding author. Tel.: +43 1 36006 6055; fax: +43 1 36006 6059.
E-mail address: paul.kosma@boku.ac.at (P. Kosma).
mixture was subjected to O-acetylation to facilitate chromato-
graphic separation of the oligomers, which furnished mainly per-
Member of the European Polysaccharide Network of Excellence (EPNOE).
0
008-6215/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2008.09.018

2
2
B. Abad-Romero et al. / Carbohydrate Research 344 (2009) 21–28
acetylated xylobiose 1 and xylotriose 4 in addition to the tetra-
ose (7) and pentaose (8) and higher oligomers. The anomeric
2.2. Sulfation reactions
acetates (
a
/b ratio ꢀ1:1.3) were then selectively deprotected
Commercially available methyl b-D-xylopyranoside 13, methyl
using Hünig-base/ammonium acetate in DMF, thereby avoiding
xylobioside 10 and methyl xylotrioside 12 were converted into
the respective intermediate stannylene acetals by reaction with
dibutyltin oxide in toluene with continuous separation of water.
The stannylene acetal products obtained after removal of the sol-
vent were dissolved in dry THF and reacted at room temperature
with an excess of trimethylamine/sulfur trioxide complex for 2–3
days, respectively. The sulfated material was isolated following
passage over cation-exchange resin and was finally purified by
chromatography on silica gel to give 14 as sodium salt in 74%
and 15, 16 and 17 as potassium salts in 30% and 27% yield, respec-
tively (Scheme 2). The structural assignments of the sulfated prod-
the formation of the corresponding N-benzyl xylosylamines or
the use of toxic hydrazinium acetate as reagent.1
4,15
This selec-
tive anomeric deacetylation under mild conditions has
previously also been effective for other mono- and oligosaccha-
1
6
rides. This way, the reducing xylobiose 2 and xylotriose 5 were
obtained in yields of 92% and 75%, respectively (Scheme 1).
Reaction of the reducing xylooligomers with trichloroacetoni-
trile/DBU afforded the previously reported
a-anomeric trichloro-
14
acetimidate derivatives 3 and 6, respectively. Transformation of
the donor 3 into the methyl glycoside 9 under promotion with
trimethylsilyltrifluoromethane sulfonate at ꢁ30 °C was accompa-
nied by hydrolysis and furnished the known methyl xylobioside
1
3
ucts followed from the lowfield-shifted C NMR signals seen for
the sulfated positions in comparison to the unsulfated educts and
1
7,18
19,20
9
in 40% isolated yield.
The use of boron-trifluoride etherate
xylodextrins, respectively (Table 1).
All sulfated compounds
as promotor for glycosidation gave better results and the previ-
ously reported methyl trioside 11 was obtained in 50% yield.
Deprotection of the acetylated methyl glycosides 9 and 11 by
Zemplén deacetylation finally afforded the known methyl glyco-
sides 10 and 12 in high yields, which were then used in the
ensuing sulfation reactions.19
displayed lowfield–shifted signals of the distal carbon 4 (Fig. 1).
The disaccharide product was obtained as a 1:2 mixture of mono-
and disulfated derivatives 15 and 16. In addition to the low-field
shifted C NMR signal of C-4 at 76.27 ppm, compound 16 revealed
a second low-field shifted carbon signal at 80.11 ppm, which could
be correlated via HSQC and HMBC-measurements to the C-2 signal
1
9
1
3
0
a
O
O
O
O
O
AcO
AcO
O
O
O
Xylooligomers
+ AcO
Tetraose (7)
Pentaose (8)
AcO
OR
AcO
AcO
OR +
AcO
OAc
OAc
OAc
OAc
OAc
1
2
3
R = Ac
R = H
R = C(=NH)CCl3
4
5
6
R = Ac
R = H
R = C(=NH)CCl 3
b
c
b
c
d
e
O
O
O
O
O
RO
RO
O
O
O
OMe
RO
RO
OMe
RO
RO
OR
RO
OR
OR
OR
OR
9
R = Ac
10 R = H
11 R = Ac
12 R = H
f
f
Scheme 1. Reagents and conditions: (a) Ac
2
O, pyr., DMAP, 28 h, rt; (b) DIPEA; NH
4
OAc, DMF, 16 h, rt, 92% for 2, 75% for 5; (c) Cl
3
CCN, DBU, MeCN, CH
2
Cl
2
, 3 h, ꢁ5 °C, 98% for 3;
5
0% for 6; (d) TMSOTf, MeOH, CH
Cl
2 2
, molecular sieves 4A, 1 h, ꢁ30 °C, 40% for 9; (e) BF
3 2
ꢂEt O, CH
2
Cl
2
, 0.5 h, ꢁ30 °C, 50% for 11; (f) 1 M NaOMe, MeOH, 8 h, rt, 90% for 10, 92%
for 12.
O
S
O
a
O
HO
HO
O
OMe
HO
HO
O
OMe
OH
HO
OH
1
3
14
O
S
O
S
O
a
O
O
O
O
O
O
O
O
10
OMe
HO
OMe
+
HO
HO
HO
HO
O
OH
OH
O
OH
O
S
O
1
5
1
6
OH
O
S
a
O
O
O
1
2
O
O
O
HO
OMe
HO
HO
HO
O
OH
OH
OH
1
7
Scheme 2. Reagents and conditions: (a) Bu
2
SnO, toluene, reflux, 15 h, then Me
3
NꢂSO
3
, THF, 48–72 h, rt, 74% for 14, 30% for 15 and 16, 27% for 17.

B. Abad-Romero et al. / Carbohydrate Research 344 (2009) 21–28
23
Table 1
2.3. Crystal structure of 14
1
3C NMR dataa for sulfated monosaccharide 14, disaccharides 10, 15, and 16, and
trisaccharides 12 and 17
The sodium salt of 14 was crystallized from ethanol/chloroform
with a small amount of water to give thin prisms. Using this mate-
rial, the crystal structure was determined as described in the
experimental section. The compound is the sodium salt hemihy-
drate of 14. It crystallizes in the triclinic space group P1 and con-
tains two independent Na ions, two independent methyl 4-O-
Residue
Carbon
d (ppm)
14
10
15
16
12
17
b-Xylp-(1?
1
2
3
4
5
104.00
74.32
77.61
71.05
67.07
103.64
74.27
101.19
80.11
73.73
76.27
63.79
103.98
74.10
77.60
71.03
67.08
103.67
74.08
75.60b
77.20
64.89
b
75.75c
77.18
64.40
sulfo-b-
cule in the unit cell, which is simultaneously the asymmetric unit
Fig. 2). The two sulfo-xylopyranoside moieties possess similar
D-xylopyranoside anions and one Na-bonded water mole-
(
?4)-b-Xylp-
bond lengths, bond angles, and conformation (Table 2). All oxygen
atoms attached to the pyran rings are in equatorial positions. The
sulfate oxygen atoms which are linked to the pyran rings exhibit
the longest of all C–O bonds (1.448 Å) and show also the signifi-
cantly longest S–O bonds (ca. 1.60 Å). The S–O mean bond lengths,
1.480(3) Å, is normal. The two Na ions display modestly distorted
octahedral coordination figures with Na–O bond distances in the
range 2.315–2.536 Å and a mean value of 2.404(4) Å. The O–Na–
O angles are in the range 70–113° and 158–165°. Each Na is coor-
dinated by one pyran-O of one xylopyranoside moiety, by two OH
oxygen atoms of another xylopyranoside moiety in a chelating
1
2
3
4
5
103.67
74.30
75.80b
78.00
64.64
103.61
74.24
b
75.77
77.91
c
64.58
?
4)-b-Xylp-OMe
1
2
3
4
5
105.80
74.78
75.81
77.37
64.73
105.86
74.63
75.83
78.24
64.48
105.83
105.77
74.45
75.48
78.74
64.05
105.88
105.85
74.61
75.64
78.13
64.40
b
74.59
74.64
75.66c
75.65b
b
c
78.17
64.90
78.11
64.42
OCH
3
57.20
57.23
57.19
57.15
57.23
57.20
fashion, by two O atoms from two SO
molecule. The two independent Na ions are linked by two SO
4 2
groups, and by one H O
a
3
Spectra (75.47 MHz) were recorded at 297 K in CD OD and referenced to 1,4-
4
dioxane (d 67.40).
b,c
groups in a bridging fashion and by the water molecule (1w) to
form a dimer. As the result, a complex 2D supramolecular sheet
structure parallel to (001) is formed, as shown in Figure ure3.
The sheets are reinforced by intra-layer hydrogen bonds donated
by the four independent OH groups and the water molecule, and
Assignments within a column may be reversed.
of the non-reducing xylopyranoside unit. The substitution at O-2
also led to high-field shifted signals of the neighboring carbons
C-1 and C-3 (Table 1.)
0
0
0
accepted by the free sulfate oxygen atoms O(8) and O(8 ) and the
00
Figure 1. Expansion plot of the HSQC-spectrum of the 4 -O-sulfated methyl b-xylotrioside (17).

2
4
B. Abad-Romero et al. / Carbohydrate Research 344 (2009) 21–28
Figure 2. Perspective view of the asymmetric unit (labelled atoms) of the sodium salt hemihydrate of 14 showing 40% ellipsoids.
Table 2
structure, which is described in Section 3. The twofold pseudo-axes
Selected bond lengths and angles for the sodium salt hemihydrate of 14
pass for instance parallel to the view direction through the water
molecules and relate the Na ions and sulfo-xylopyranoside moie-
ties with unprimed atom labels to those having primed atom labels
(for atom labels see Fig. 2).
Molecule 1
Molecule 2
Bond lengths (Å)
Na–O(2)
Na–O(3)
Na–O(4)
Na–O(6)
Na–O(7 ), Na –O(7)
2.494(4)
2.419(4)
2.436(3)
2.338(4)
2.315(4)
2.366(4)
2.536(4)
2.428(3)
2.464(3)
2.343(4)
2.328(4)
2.382(4)
3
. Conclusions
0
0
0
Na–O(1w), Na –O(1w)
Regioselective sulfation of unprotected methyl xylooligosaccha-
rides may be achieved in fair yields at the distal 4-hydroxy-group
via intermediate dibutylstannylene acetal formation followed by
treatment with the trimethylamine/sulfur trioxide complex. A
S–O(5)
S–O(6)
S–O(7)
S–O(8)
1.604(3)
1.440(3)
1.448(4)
1.440(3)
1.597(3)
1.441(3)
1.430(4)
1.438(3)
high-resolution crystal structure of sodium methyl b-
D-xylopyran-
oside 4-O-sulfate hemihydrate was obtained.
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(1)–O(1)
C(1)–O(2)
C(2)–O(3)
C(3)–O(4)
C(4)–O(5)
C(5)–O(1)
C(6)–O(2)
1.499(5)
1.517(5)
1.522(5)
1.527(6)
1.436(5)
1.385(4)
1.418(4)
1.423(5)
1.448(4)
1.426(5)
1.423(6)
1.523(5)
1.509(5)
1.521(5)
1.528(6)
1.437(5)
1.376(5)
1.412(4)
1.426(5)
1.448(4)
1.414(5)
1.435(5)
4
. Experimental
4.1. General
Concentration of solutions was performed under diminished
pressure at temperatures <40 °C. Methyl xylopyranoside was pur-
chased from Fluka. A hydrolytically degraded sample of xylan
was obtained from Lenzing AG. Dichloromethane and dry pyridine
Bond angles (°)
C(5)–O(1)–C(1)
O(1)–C(1)–C(2)
C(1)–C(2)–C(3)
C(2)–C(3)–C(4)
C(3)–C(4)–C(5)
C(4)–C(5)–O(1)
C(4)–O(5)–S
were dried by refluxing with CaH
and stored under argon over molecular sieves 0.4 nm. DMF was
stirred with CaH (5 g per L) for 16 h at 20 °C, distilled under re-
duced pressure and stored over activated molecular sieves
0.3 nm. Column chromatography was performed on Silica Gel 60
(230–400 mesh, Merck). Analytical TLC was performed using Silica
Gel 60 F254 HPTLC plates with 2.5 cm concentration zone (Merck).
2
(5 g per L) for 16 h, then distilled
111.4(3)
111.8(3)
109.5(3)
107.7(3)
111.3(3)
110.4(3)
110.8(3)
118.6(2)
109.3(3)
107.9(3)
110.9(3)
112.6(3)
110.0(3)
118.8(2)
2
Hydrogen bonds (Å)
O(3)?O(8)
O(4)?O(1)
Spots were detected by treatment with anisaldehyde—H
Size—exclusion chromatography was performed on Bio-GelÒ P-2
Gel, Extra fine <45 m (wet) from Bio-Rad Laboratories. Ion ex-
2 4
SO .
2.876(4)
2.842(4)
2.852(5)
2.830(4)
2.934(5)
2.823(5)
0
l
O(1w)?O(8), O(1w)?O(8 )
change chromatography was performed on a Dowex 50 W ꢃ 8 re-
Dimensions of molecule 2 refer to atoms with corresponding atom labels primed,
except where given by a second set of atom labels.
sin, H+ form, 50–100 mesh and/or on a ChelexÒ 100, Na+-form,
2
00–400 mesh resin from Fluka which was transformed into the
+
K -form by treatment with HCl (1 M) and KOH (1 M). Melting
points were determined on a Kofler hot stage microscope and are
uncorrected. Optical rotations were measured with a Perkin–Elmer
0
pyranose oxygen atoms O(1) and O(1 ) (see Table 2 for hydrogen
bond lengths). The sheets described are stacked one above the
other along the c-axis and are held together only by van-der-Waals
forces, as is evident from Figure 3. This figure reveals also clearly
the monoclinic pseudo-symmetry, pseudo-space group C2, of the
2
243 B polarimeter. NMR spectra were recorded at 297 K in D O and
1
CDCl
300.13 MHz,
3
with a Bruker DPX 300 or Avance 400 spectrometer ( H at
1
3
1
13
C at 75.47 MHz or H at 400.13 MHz,
C at

B. Abad-Romero et al. / Carbohydrate Research 344 (2009) 21–28
25
Figure 3. Packing diagram of the sodium salt hemihydrate of 14 in a view down the a-axis of the triclinic unit cell. This view direction shows clearly the pseudo-symmetry of
the structure with twofold pseudoaxes and pseudo-screw axes indicated by the symbols ‘‘2” and ‘‘2 ” in the lower right part of the figure (all axes along view direction). The
1
four outermost symbols ‘‘2” represent the corners of the monoclinic C2 pseudocell. Moreover, the layer-like architecture of the structure parallel to (001) can be recognized.
1
1
00.61 MHz, respectively) using standard Bruker NMR software. H
T = 297 K,
a = 6.149(2) Å,
b = 9.638(4) Å,
c = 10.117(6) Å,
3
NMR spectra were referenced to tetramethylsilane or 2,2-di-
a
= 79.002(8)°, b = 76.291(7)°,
c
= 71.942(7)°, V = 549.3(4) Å ,
methyl-2-silapentane-5-sulfonic acid. 13C NMR spectra were refer-
Z = 1,
qcalc = 1.664 g/cm , l = 0.364 mm . Of 7255 reflections col-
3
ꢁ1
enced to chloroform for solutions in CDCl
7.40) for solutions in D O). For mass spectrometry analyses, sam-
ples were dissolved in the appropriate amount of water to give a
solution of approx. 1 nmol/ L. Just before analysis an aliquot of
the respective sample was diluted in 50% aq acetonitrile containing
.1% formic acid to give a final concentration of ꢀ10 pmol/ L. This
3
(d 77.00) or dioxane (d
lected up to hmax = 27.5°, 5305 were independent, Rint = 0.143,
6
2
and 4406 were observed (I > 2
r
(I)); final
R
indices:
R
1
=
P
P
P
2
2
2
||F
o
| ꢁ |F
c
||/ |F
o
| = 0.072 (all data), wR
2
¼ ½ ðwðF ꢁ F Þ Þ=
o
c
P
2
2
1=2
l
ðwðF Þ Þꢄ ¼ 0:152 (all data). Atomic parameters and further
o
details of the structure determination have been deposited. CCDC
698892 contains the supplementary crystallographic data for this
paper. Copies of this information may be obtained free of charge
from the Director, Cambridge Crystallographic Data Centre, 12 Un-
ion Road, Cambridge, CB2 1EZ, UK. (fax: +44-1223-336033, e-mail:
deposit@ccdc.cam.ac.uk or via: www.ccdc.cam.ac.uk). Views of the
structure are shown in Figures 2 and 3. Selected bond lengths and
angles are given in Table 2. The structure displays a distinct mono-
clinic pseudosymmetry with pseudo space group C2, in which two-
fold pseudo-axes passing through the water molecules relate pairs
0
l
solution was subjected to offline ESI-TOFMS on a Waters Micro-
mass Q-TOF Ultima Global. Capillary voltage was adjusted to ob-
tain approx. 200 counts/s. The MS had been previously tuned
with [Glu1]-fibrinopeptide B to give highest possible sensitivity
and a resolution of ca. 10.000 (FWHM). Mass tuning of the TOF
analyzer was done in the tandem MS mode using again [Glu1]-
fibrinopeptide B. Elemental analyses were provided by Dr. J. Thein-
er, Mikroanalytisches Laboratorium, Institut für Physikalische
Chemie, Universität Wien.
of Na cations and pairs of methyl 4-O-sulfo-b-D-xylopyranoside an-
ions. The matrix ꢁ120/ꢁ100/0ꢁ11 transforms the primitive unit
4
.2. X-ray crystallographic study
cell into this pseudomonoclinic C-centred cell of the dimensions
0
0
0
0
0
0
a = 18.327, b = 6.149, c = 12.571 Å,
a = 87.31°, b = 128.99°, c =
0
3
0
0
The sodium salt of 14 was crystallized from ethanol/chloroform
89.46°, and V = 1099 Å . The deviations of
a trial structure refinement in space group C2 that resulted in dis-
tinctly larger R-indices than given above (R = 0.153, wR = 0.274)
a and c from 90° and
in the presence of a small amount of water to give thin prisms of
modest quality. X-ray data were collected with a prism of
1
2
0
.60 ꢃ 0.10 ꢃ 0.08 mm on a Bruker Smart APEX CCD diffractometer
using graphite-monochromated Mo-K radiation (k = 0.71073 Å)
and -scan frames covering a complete sphere of the reciprocal
space. After data integration with program SAINT
proved that the real structure of the compound is triclinic P1. For
crystal structure determinations of three sodium carbohydrate sul-
fonates see Ref. 23.
a
x
21
,
the structure
2
was solved by direct methods and refined on F with the program
4.3. Preparation of acetylated xylooligosaccharides
2
2
package SHELX97. All non-hydrogen atoms were refined anisotrop-
ically using DELU 0.03 0.03 restraints for all Uij and SAME restraints
for the 1–2 and 1–3 distances of the two independent sulfoxylo-
pyranoside anions. Hydrogen atoms were inserted in idealized
positions and were refined riding with the atoms to which they
The oligosaccharide mixture from Lenzing AG (4 g) containing
xylobiose and xylotriose was dried under vacuum and dissolved
in dry pyridine (10 mL). The solution was cooled to 5 °C, and 4-
N,N-dimethylaminopyridine (20 mg, 0.16 mmol) and acetic anhy-
dride (60 mL) were added. After 28 h, the mixture was cooled to
0 °C, MeOH (100 mL) was added, and the solution was stirred for
were bonded. Crystal data are
C
2
(C
6
H
11
O
5
SO
3
Na)ꢂH
2
O =
12
H24Na
2
O
17
S
2
, M = 550.41, triclinic, space group P1 (no. 1),
r

2
6
B. Abad-Romero et al. / Carbohydrate Research 344 (2009) 21–28
3
0 min. The mixture was co-evaporated three times with toluene
1H, J1,2 3.6 Hz, H-1), 5. 50 (t, 1H, J3,2 = J3,4 10.1 Hz, H-3), 5.095 (t,
0
(
50 mL). The resulting syrupy product (10 g) was purified by col-
1H, J
3
0
,2
0
= J
3
0
,4
0
7.6 Hz, H-3 ), 5.00 (dd, 1H, J2,3 10.1 Hz, H-2), 4.88
0
umn chromatography (n-hexane–EtOAc). The polarity of the sys-
tem was increased from 2:1?2:1.5?1:1 n-hexane–EtOAc to
yield first 2.3 g of hexa-O-acetyl-xylobiose (1) as a colorless syrup
followed by 1.6 g of octa-O-acetyl-xylotriose (4) as well as frac-
tions containing a mixture of 1 and 4. Further elution of the column
afforded 40 mg of deca-O-acetylxylotetraose (7) as a colorless syr-
up; R
showed a mixture of
data for b isomer: d 5.64 (d, 1H, J1,2 7.2 Hz, H-1), 5.13 (t, 1H,
(ddd, 1H, J
4
0
,3
0
= J
4
0
,5b
0
7.6, J
4
0
,5a
0
0
4.6 Hz, H-4 ), 4.80 (dd, 1H, J
2
0
,1
0
0
0
5.8 Hz, H-2 ), 4.58 (d, 1H, H-1 ), 4.12 (dd, 1H, J5a
3.90–3.77 (m, 3H, H-4, H-5a, H-5b), 3.41 (dd, 1H, H-5 b), 2.06 (s,
0
,5b
0
12.0, H-5a ),
0
1
3
6H), 2.04 (s, 6H), and 2.01 (s, 3H, 5 ꢃ CH
CDCl
(C@NH), 99.70 (C-1 ), 93.17 (C-1), 90.73 (CCl
3
). C NMR (75 MHz,
3
): d 170.11, 170.03, 169.86, 169.55, 169.14 (5 ꢃ CO), 161.11
0
3
), 74.90 (C-4), 70.31,
= 0.5 (2:3 n-hexane–EtOAc). 1H NMR (300 MHz, CDCl
:b anomers in a ratio of 1:1.25, respectively;
70.24, 70.03, 69.78 (C-2, C-3, C-2 , C-3 ), 68.21 (C-4 ), 61.46 (C-5,
C-5 ), 20.90, 20.77 (double intensity), 20.65, 20.49 (5 ꢃ CH
0
0
0
f
3
) of 7
0
a
3
).
0
00
0
0
00 00 00
J3,2 = J3,4 8.4 Hz, H-3), 5.09 (t, 1H, J
3
000,2000 = J
3
000,4000 7.8 Hz, H-3 ), 5.06
4.6. 2,3,2 ,3 ,2 ,3 ,4 -Hepta-O-acetyl-xylotriose (5)
0
(
3
t, 1H, J
3
0
,2
0
= J
3
0
,4
0
8.4 Hz, H-3 ), 5.05 (t, 1H, J
4
00,300 = J
3
00,200 8.2 Hz, H-
0
0
000
), 4.96 (dd, 1H, H-2), 4.87 (dd, 1H, J
4
000,5a000 4.7 Hz, H-4 ), 4.79
Xylotriose peracetate 4 (2.21 g, 3.06 mmol) was treated with
DIPEA (5.24 mL, 30.6 mmol, 10 equiv) in dry DMF (60 mL) using
NH OAc crystals (2.83 g, 36.7 mmol) following the same procedure
4
as described for 2. Column chromatography using 2:1?1:2 n-hex-
0
00
0
00
(
dd, 1H, J
1
000,2000 6.0 Hz, H-2 ), 4.74 (dd, 2H, H-2 , H-2 ), 4.55 (d,
00,200 6.6 Hz, H-1 ), 4.47 (d, 1H, J
.6 Hz, H-1 ), 4.09 (dd, 1H, J5a000,4000 4.7, J5a000,5b000 12.0 Hz, H-5a ),
0
00
00
1
6
3
H, H-1 ), 4.47 (d, 1H, J
1
1
0
,2
0
0
000
.995 (dd, 1H, J5a,4 5.1, J5a,5b 12.0 Hz, H-5a), 3.95 and 3.94 (m, 2H,
ane–EtOAc gave 1.82 g (75%) of 5 as an amorphous material;
0
0
0
0
00
1
H-5 a, H-5a ), 3.85–3.75 (m, 3H, H-4, H-4 , H-4 ), 3.46 (dd, 1H,
R
f
= 0.5 (1:2 n-hexane–EtOAc); H NMR (300 MHz, CDCl
3
) for
a-iso-
0
00
J5a,4 8.9 Hz, H-5b), 3.39 (dd, 1H, J
4
000,5b000 7.6 Hz, H-5 b), 3.31 (m,
mer: d 5.42 (dd, 1H, J3,2 8.2, J3,4 9.8 Hz, H-3), 5.32 (t, 1H, J1,2 = J1,OH
0
00
00
2
H, H-5b , H-5b ), 2.06 – 2.00 (6s, 30H, 10 ꢃ CH
3
); data for
a
iso-
3.7 Hz, H-1), 5.09 (t, 1H, J
3
00,200 7.7 Hz, H-3 ), 5.06 (t, 1H, J
3
0
,2
0
= J
3
0
,4
0
0
00
mer: d 6.20 (d, 1H, J1,2 3.7 Hz, H-1), 5.36 (dd, 1H, J3,2 9.0, J3,4
0.1 Hz, H-3), 4.94 (dd, 1H, H-2); remaining signals are similar to
the b isomer. Finally dodeca-O-acetyl-xylopentaose peracetate (8)
was isolated as a syrup (20 mg); R = 0.3 (2:3 n-hexane–EtOAc);
) for b isomer: d 5.64 (d, 1H, J1,2 7.2 Hz,
8.5 Hz, H-3 ), 4.87 (ddd, 1H, J
4
00,500
a
4.6, J
4
00,300 = J
4
00,500
b
7.7 Hz, H-4 ),
6.7 Hz, H-2 ),
0
0
0
1
4.79 (dd, 1H, J
2
00,100 5.9 Hz, H-2 ), 4.74 (dd, 1H, J
4.73 (dd, 1H, H-2), 4.56 (d, 1H, H-1 ), 4.49 (d, 1H, Hz, H-1 ), 4.09
(dd, 1H, J5a00,5b00 11.9 Hz, H-5a ), 4.01–3.91 (m, 2H, H-5a, H-5a ),
2
0
,1
0
0
0
0
0
0
0
f
1
0
H NMR (300 MHz, CDCl
H-1), 5.16–5.01 (m, 4H, H-3, H-3 , H-3 , H-3 ), 4.81 – 4.70 (m,
3
3.87–3.72 (m, 2H, H-4, H-4 ), 3.67 (dd, 1H, J5b
0
,4
0
,5a
4.2, J5b 9.2 Hz,
0 0
0
00
000
0
00
H-5b ), 3.39 (dd, 1H, J5b00,5a00 12.0 Hz, H-5b ), 3.36–3.28 (m, 1H, H-
0
00
000
0000
0000
13
6
H, H-2, H-2 , H-2 , H-2 , H-2 , H-4 ), 4.56 (d, 1H, J
1
0000,20000
5b), 2.08–2.02 (21H, 7 ꢃ CH
3
).
3
C NMR (75 MHz, CDCl ): d
169.98, 169.89, 169.84, 169.72, 169.42, 169.39, 169.18 (CO),
100.46 (C1 ), 99.38 (C1 ), 95.86 (C1b), 90.24 (C1
74.16 (C4), 71.92 (C3), 70.95 (C2 ), 70.27 (C2 ), 70.28 (C3 ), 69.97
0
000
0
00
000
5
.9 Hz, H-1 ), 4.47 (d, 3H, J 6.6 Hz, H-1 , H-1 , H-1 ), 4.02–3.87
0
00
000
0000
0
00
0
(
m, 5H, H-5a, H-5a , H-5a , H-5a , H-5a ), 3.83 – 3.76 (m, 4H,
a
), (74.73 (C4 ),
0
00
000
0
00
0
00
00
H-4, H-4 , H-4 , H-4 ), 3.49–3.27 (m, 5H, H-5b, H-5b , H-5b , H-
5
0
00
0000
0
00
0
00
b , H-5b ) 2.09–2.02 (m, 36H, 12 ꢃ CH
3
).
(C3 ), 69.74 (C2), 68.25 (C4 ), 63.37 (C5), 62.60 (C5 ), 61.48 (C5 ),
2
1.03, 20.89, 20.81, 20.75, and 20.62 (CH
3
).
0
0
0
4
.4. 2,3,2 ,3 ,4 -Penta-O-acetyl-xylobiose (2)
0
0
0
4
.7. Methyl 2,3,2 ,3 ,4 -penta-O-acetyl-b-
-xylobioside (10)
D-xylobioside (9) and
A solution of compound 1 (2.5 g, 4.6 mmol) in a mixture of dry
methyl b-
D
DMF (10 mL) and DIPEA (8 mL, 46.8 mmol, 10 equiv) was stirred
with ammonium acetate (4.3 g, 56.1 mmol; crystals were pre-
washed with 2 ꢃ 50 mL portions of diethylether and were dried
for 15 min under diminished pressure) for 16 h at rt. The reaction
mixture was decanted from the undissolved crystals of ammonium
Dry MeOH (31.8
molecular sieves (3 Å) in dry CH
under Ar for 30 min. -Trichloroacetimidate derivative 3 (0.5 g,
0.78 mmol) was dissolved in dry CH Cl (5 mL) and cooled to
ꢁ30 °C in a separate flask. TMSOTf (36.1 L, 0.2 mmol) was added
to the flask containing MeOH in CH Cl and the trichloroacetimi-
date solution was added subsequently. The reaction mixture was
stirred for 1 h, then diluted with CH Cl (50 mL) and neutralized
l
L, 0.78 mmol) was placed in a flask containing
2
Cl
2
(5.0 mL) and cooled to ꢁ30 °C
a
2
2
acetate, diluted with CH
NaHCO
centrated under diminished pressure. The resulting colorless syrup
2
Cl
2
(300 mL) and washed with 1 M aq
, and con-
l
3
(2 ꢃ 20 mL), water (20 mL), dried over MgSO
4
2
2
was submitted to silica gel chromatography (3:2 EtOAc–n-hexane)
2
2
1
4
to yield 2.1 g (92%) of 2 as colorless crystals; mp 158–163 °C, lit
mp 171 °C; R
= 0.4 (3:2 EtOAc–n-hexane); 1H NMR (300 MHz,
CDCl ) for isomer: d 5.43 (t, 1H, J3,2 = J3,4 9.4 Hz, H-3), 5.33 (t,
by adding triethylamine (0.2 mL) with a syringe. Molecular sieves
were filtered off and the filtrate was concentrated under dimin-
ished pressure. Purification of the residue by silica gel column
f
3
a
1
3
4
1
H, J1,2 4.0, J1,OH 3.4 Hz, H-1), 5.09 (t, 1H, J
), 4.88 (ddd, 1H, J
3
0
,2
0
7.5, J
3
0
,4
0
8.0 Hz, H-
chromatography (1:2?2:3 EtOAc–n-hexane) gave 160 mg of 9
0
0
0
17,18
0
0
4.3, J
0
0
7.5 Hz, H-4 ), 4.80 (dd, 1H, H-2 ),
(40%) as colorless crystals, mp 138–141 °C, lit.
mp 145–
4
,5
a
4
,5
b
0
1
.79 (dd, 1H, H-2), 4.57 (d, 1H, J
1
0
,2
0
5.7 Hz, H-1 ), 4.11 (dd, 1H, J
5
0
a,5
0
b
146 °C; R
f
= 0.5 (2:1 EtOAc–n-hexane). H NMR (300 MHz, CDCl
3
):
0
0
2.5 Hz, H-5 a), 3.85–3.70 (m, 3H, H-5a, H-4, H-5b), 3.40 (dd, 1H,
d 5.12 (t, 1H, J3,2 8.5 Hz, H-3), 5.09 (t, 1H, J
(ddd, 1H, J5a
3
0
,2
0
8.0 Hz, H-3 ), 4.87
8.0 Hz, H-4 ), 4.84 (dd, 1H, H-2), 4.80 (dd,
5.9 Hz, H-2 ), 4.56 (d, 1H, H-1 ), 4.34 (d, 1H, J1,2 7.3 Hz,
0
0
J
5
0
b,4
0
7.5 Hz, H-5 b), 2.79 (d, 1H, OH), 2.08, 2.06, 2.05, 2.04 (4s,
0
,4
0
4.3, J
4
0
0
,3
0
1
0
1
5H, 5 ꢃ CH
3
). The H NMR spectrum also indicated the presence
1H, J
1
0
,2
0
0
of the b isomer in approx 30%.
H-1), 4.10 (dd, 1H, J5a
0
,4
0
4.3, J5a
0
,5b
0
11.9 Hz, H-5a ), 4.00 (dd, 1H,
J
5a,5b 11.6, J5a,4 5.2 Hz, H-5a), 3.84 (ddd, 1H, J4,5b 9.0 Hz, H-4), 3.46
0
0
0
0
4
.5. 2,3,2 ,3 ,4 -Penta-O-acetyl-
a
-D
-xylobiosyl
,4
(s, 3H, Me), 3.40 (dd, 1H, J5b 7.7 Hz, H-5b ), 2.05 (s, 6H), 2.04 (s,
0 0
1
3
trichloroacetimidate (3)
6H) and 2.03 (s, 3H, 5 ꢃ Ac). C NMR (75 MHz, CDCl
3
): d 101.92
0
0
(
C-1), 99.57 (C-1 ), 74.93 (C-4), 72.49 (C-3), 71.20 (C-3 ), 70.38
0
0
0
Trichloroacetonitrile (2.4 mL, 24.4 mmol) and DBU (150
.6 mmol) were added successively to a solution of reducing penta-
acetate 2 (1.0 g, 2.0 mmol) in dry CH Cl (12 mL) at –5 °C. After 3 h
lL,
and 70.29 (C-2,2 ), 68.25 (C-4 ), 62.81 (C-5), 61.43 (C-5 ), 56.79
(OMe), 20.96, 20.75, 20.67, 20.59, 20.57 (5 ꢃ CH ).
Methyl xylobioside 10 was obtained by Zemplén reaction of 9
(0.77 g, 1.53 mmol) using 1 M NaOMe (240 L, 7.6 mmol) in dry
0
3
2
2
the reaction mixture was concentrated and the residue was purified
l
by silica gel column chromatography (1:1?2:1 EtOAc–n-hexane)
MeOH (10 mL) at rt for 2 h. The solution was made neutral by addi-
tion of DOWEX cation-exchange resin (H ) and the suspension was
filtered. The filtrate was concentrated and the residue was purified
+
to yield 1.2 g (98%) of 3 as colorless foam; R
f
= 0.6 (2:1 EtOAc–n-
1
hexane); H NMR (300 MHz, CDCl
3
): d 8.64 (s, 1H, NH), 6.42 (d,

B. Abad-Romero et al. / Carbohydrate Research 344 (2009) 21–28
27
+
by silica gel column chromatography (10:20:1?20:20:1 EtOH–
3.39 mmol) was added. After being stirred for 48 h at rt, Na chelex
ion exchange resin (5 g) was added to remove salts. The reaction
mixture was filtered, and the solvent was evaporated under dimin-
1
CHCl –H
3 2
O) to yield 10 as a white solid. Yield: 0.40 g, (90%);
H
0
NMR (300 MHz, MeOD): d 4.32 (d, 1H, J
1
0
,2
0
7.4 Hz, H-1 ), 4.13 (d,
1
3
H, J1,2 7.4 Hz, H-1), 4.00 (dd, 1H, J5a,4 5.2, J5a,5b 11.6 Hz, H-5a),
3
ished pressure. The residue was diluted with CH OH (5 mL), then
0
+
.89 (dd, 1H, J5a
0
,4
0
5.2, J5a
0
,5b
0
0
11.3 Hz, H-5a ), 3.67–3.56 (m, 1H,
loaded onto a cation exchange resin column (Chelex 100, Na -
form; 200–400 mesh, 1.5 ꢃ 7 cm). The column was eluted with
MeOH. One molar of NaOH was added until pH was between 7
and 8. The eluent was concentrated to a residue that was purified
H-4), 3.53–3.41 (m, 1H, H-4 ), 3.51 (t, 1H, J3,2 = J3,4 9.0 Hz, H-3),
0
0
3
.34 (s, 3H, OMe), 3.33–3.26 (m, 3H, H-3 , H-5b, H-5b ), 3.23–
0
13
3
.16 (m, 2H, H-2, H-2 ); C NMR data see Table 1.
by chromatography on silica gel using 1:3 EtOH–CHCl
give the sulfated product 14 (0.7 g, 74%), which crystallized from
the same eluent EtOH–CHCl as colorless needles; mp 189–
3
as eluent to
0
0
00 00 00
4
.8. Methyl 2,3,2 ,3 ,2 ,3 4 -hepta-O-acetyl-b-
D-xylotrioside (11)
and methyl b-
D
-xylotrioside (12)
3
2
3
1
1
91 °C; ½
a
ꢄ
ꢁ25 (c 0.9, CH
3
OH); H NMR (300 MHz, MeOD): d
D
Xylotriose 5 (1.4 g, 1.97 mmol) was treated with Cl
2.48 mL, 24 mmol) and DBU (86 L, 0.57 mmol) in dry CH
3
CCN
Cl
4.24–4.15 (m, 2H, H-4, H-5a), 4.13 (d, 1H, J1,2 7.5 Hz, H-1), 3.51
(
(
l
2
2
(t, 1H, J3,2 = J3,4 9.0 Hz, H-3), 3.48 (s, 3H, OMe), 3.35 (m, 1H, H-
1
3
30 mL) at ꢁ5 °C following the same procedure as described before
5b), 3.23 (dd, 1H, H-2). C NMR see Table 1. Anal. Calcd for
SNaꢂ0.5H O: C, 26.19, H, 4.395, S, 11.65. Found: C, 26.13,
H, 4.45, S, 11.38.
for the synthesis of compound 3. After 3 h the solution was concen-
trated and the residue was purified by silica gel column chroma-
tography (1:1 n-hexane–EtOAc) to yield 6 as a white solid
C H
6 11
O
8
2
(
0.81 g, 50%) which was immediately subjected to the subsequent
reaction. Dry MeOH (50 L, 1.23 mmol) and molecular sieves (3 Å)
were cooled to ꢁ30 °C under Ar. The -trichloroacetimidate donor
(0.64 g, 0.75 mmol) was dissolved in CH Cl (5 mL) and cooled
under Ar to ꢁ30 °C. A solution of BF ꢂEt O (24 L, 0.18 mmol) in
CH Cl (3 mL) was added with a syringe into the flask containing
MeOH and subsequently the solution of 6 was added slowly at
30 °C. After 0.5 h, the reaction was stopped by adding Et
0.2 mL) with a syringe. The solution was filtered and the filtrate
4.10. Methyl 4-O-sulfo-b-
xylopyranoside potassium salt (15) and methyl 2,4-di-O-sulfo-b-
-xylopyranosyl-(1?4)-b- -xylopyranoside dipotassium salt
(16)
D-xylopyranosyl-(1?4)-b-D-
l
a
D
D
6
2
2
3
2
l
2
2
Methyl xylobioside 10 (210 mg, 0.7 mmol) was converted into
the corresponding stannylene derivative following the same proce-
dure as described for the synthesis of 14 using dibutyltin oxide
(381 mg, 1.53 mmol) in dry toluene (150 mL) for 48 h. The solvent
was removed under diminished pressure and the residue was dis-
ꢁ
3
N
(
was concentrated in vacuo. The product was purified by silica gel
column chromatography (2:1?3:2 n-hexane–EtOAc) to yield 11
solved in dry THF (15 mL). SO
3
ꢂMe
3
N (140 mg, 1.00 mmol) was
(
(
9
0.27 g, 50%) as colorless prisms; mp 93–95 °C and 140–142 °C
added to the solution and the reaction mixture was stirred for
1
+
dimorphous). H NMR (400 MHz, CDCl
3
): d 5.10 (t, 1H, J3,2 = J3,4
72 h at rt. K chelex ion exchange resin was added, the mixture
00
.0 Hz, H-3), 5.09 (t, 1H, J3”,4” = J3”,2” 8.0 Hz, H-3 ), 5.065 (t, 1H,
was filtered, and the solvent was removed under reduced pressure.
The residue was dissolved in MeOH (2 mL), loaded onto a cation
exchange resin column (Chelex 100, K -form; 200–400 mesh,
1.5 ꢃ 7 cm). After elution with MeOH, 1 M KOH was added to ad-
just the pH to 8.0. MeOH was removed under diminished pressure
and the product was purified by silica gel column chromatography
0
J
3 ,4 3 ,2
= J
0 0 0 0 8.8 Hz, H-3 ), 4.88 (ddd, 1H, J5a00,400 4.8 Hz, H-4”), 4.83
0
0
+
(
(
dd, 1H, J1,2 7.6 Hz, H-2), 4.80 (dd, 1H, J
1
00,200 6.0 Hz, H-2 ), 4.75
0
00
0
dd, 1H, J
1
0
,2
0
6.5 Hz, H-2 ), 4.54 (d, 1H, H-1 ), 4.48 (d, 1H, H-1 ),
00
4
1
1
3
5
.34 (d, 1H, H-1), 4.09 (dd, 1H, J5a00,5b00 12.4 Hz, H-5a ), 3.97 (dd,
H, J5a,4 5.6, J5a,5b 12.4 Hz, H-5a), 3.94 (dd, 1H, J5a 4.8, J5a
2.0 Hz, H-5a ), 3.83–3.77 (m, 2H, H-4, H-4 ), 3.46 (s, 3H, OMe),
0
0
0 0
,5b
,4
0
0
3
(1:3 EtOH-CHCl ,) yielding a mixture of mono-sulfated (15) and
00
.39 (dd, 1H, J5b00,400 7.6 Hz, H-5b ), 3.32 (dd, 1H, J
0
0
7.6 Hz, H-
).
Methyl xylotrioside heptaacetate 11 (180 mg, 0.249 mmol) was
dissolved in dry MeOH (5 mL) and a solution of 1 M methanolic
NaOMe (80 L, 2.49 mmol) was added. The solution was stirred
disulfated (16) derivative in a ratio of 1:2, respectively, as colorless
5
b,4
0
1
b ), 3.30 (dd, 1H, J 9.5 Hz, H-5b) and 2.06-2.03 (21H, 7 ꢃ CH
3
syrup. Yield: 46 mg, (30%); H NMR (300 MHz, MeOD) for 15: d
0
0
4.36 (d, 1H, J
1
0
,2
0
7.6 Hz, H-1 ), 4.25 (m, 1H, H-4 ), 4.20 (m, 1H, H-
0
5a ), 4.14 (d, 1H, J1,2 7.4 Hz, H-1), 4.02 (dd, 1H, J5a,4 5.1, J5a,5b
l
11.6 Hz, H-5a), 3.66–3.57 (m, 1H, H-4), 3.48 (s, 3H, OMe), 3.49
+
0
0
0
at rt for 8 h. Dowex ion-exchange resin (H -form) was added until
the pH of the suspension was neutral and the resin was filtered off
and washed with MeOH (3 ꢃ 5 mL). The filtrate was concentrated
under diminished pressure and the residue was finally purified
(m, 2H, H-3, 3 ), 3.31 (m, 2H, H-5b, 5b ), 3.30 (m, 1H, H-2 ), 3.21
1
(dd, 1H, H-2); H NMR (300 MHz, MeOD) for 16: d 4.66 (d, 1H,
0
0
0
J
1
0
,2
0
6.4 Hz, H-1 ), 4.30 (m, 1H, H-5a ), 4.28 (m, 1H, H-4 ), 4.15 (d,
0
1H, J1,2 7.4 Hz, H-1), 4.11 (dd, 1H, J
2
0
,3
0
8.0 Hz, H-2 ), 4.08 (dd, 1H,
0
by silica gel column chromatography (15:20:1 CHCl
yielding 12 as a colorless amorphous solid (99 mg, 92%). H NMR
3
–EtOH–H
2
O)
J5a,4 4.9, J5a,5b 12.0 Hz, H-5a), 3.81 (t, 1H, J
3
0
,4
0
7.8 Hz, H-3 ), 3.62
1
0
(m, 1H, H-4), 3.51 (t, 1H, J3,4 8.7 Hz, H-3), 3.49 (dd, 1H, H-5b ),
0
(
7
300 MHz, MeOD): d 4.34 (d, 1H, J
1
0
,2
0
7.5 Hz, H-1 ), 4.32 (d, 1H, J
1
00,200
3.48 (s, 3H, OMe), 3.36 (dd, 1H, J5b,4 9.5 Hz, H-5b), 3.20 (dd, 1H,
00
13
.4 Hz, H-1 ), 4.12 (d, 1H, J1,2 7.5 Hz, H-1), 4.04 (dd, 1H, J5a
5.2 Hz, H-5a ), 4.01 (dd, 1H, J5a,5b 11.4, J5a,4 5.2 Hz, H-5a), 3.88
dd, 1H, J5a00,5b00 11.3, J5a00,400 5.3 Hz, H-5a ), 3.66 and 3.65 (m, 2H, H-
, H-4), 3.49 (m, 1H, H-4 ), 3.49 (s, 3H, OMe), 3.45 and 3.44 (2t, 2H,
8.8 Hz, H-3 , H-3), 3.36 (m, 1H, H-5b), 3.34 (t,
H, H-3 ), 3.34 (m, 1H, H-5b ), 3.26 (dd, 1H, H-2 ), 3.23 (dd, 1H,
0
,5b
0
11.4,
J2,3 8.7 Hz, H-2);
C NMR data see Table 1. ESI-TOFMS: m/
0
J
5a
0
,4
0
z = 523.03 [M+3Na] calcd 523.22.
00
(
4
0
00
4.11. Methyl 4-O-sulfo-b-
D-xylopyranosyl-(1?4)-b-D-
0
J
3,2 = J3,4 = J
3
0
,2
0
= J
3
0
,4
0
xylopyranosyl-(1?4)-b- -xylopyranoside potassium salt (17)
D
00
0
0
1
0
0
00
13
H-5b ), 3.21 (dd, 1H, H-2 ) and 3.185 (dd, 1H, H-2). C NMR data
see Table 1.
Methyl xylotrioside 12 (62 mg, 0.14 mmol) was transformed
into the stannylene derivative and subsequently into the regiose-
lectively sulfated trisaccharide 17 following the same procedure
4
.9. Methyl 4-O-sulfo-b-
D
-xylopyranoside sodium salt (14)
as described above by treatment with Bu
in dry toluene (100 mL) at 120 °C. After workup and treatment
with Me (62 mg, 0.45 mmol) in dry THF (5 mL) for 72 h at
rt, K chelex ion exchange resin was added, the suspension was fil-
tered and the solvent was removed in vacuo. The residue was puri-
2
SnO (140 mg, 0.56 mmol)
Methyl b- -xylopyranoside 13 (0.5 g, 3.045 mmol) and dibutyl-
D
3
NꢂSO
3
+
tin oxide (0.818 g, 3.29 mmol, 1.08 equiv) were heated at reflux in
toluene (100 mL) for 15 h with continuous separation of water. The
solution was concentrated under reduced pressure. The residue
fied by silica gel column chromatography (3:1 EtOH–CHCl
3
) and
was taken up in dry THF (15 mL) and SO
3 3
ꢂMe N (0.472 g,
then on a G-25 Sephadex PD-10 column (water) which gave 17

2
8
B. Abad-Romero et al. / Carbohydrate Research 344 (2009) 21–28
2
D
0
O); 1H NMR
as syrup. Yield: 21 mg (27%); ½
aꢄ
ꢁ50 (c 0.3, H
2
4. Stone, A. L.; Melton, D. J.; Lewis, M. S. Glycoconjugate J. 1998, 15, 697–712.
5. Yamagaki, T.; Tsuji, Y.; Maeda, M.; Nakanishi, H. Biosci. Biotechnol. Biochem.
00
(
400 MHz, MeOD): d 4.38 (d, 1H, J
1
00,200 8.0 Hz, H-1 ), 4.36 (d, 1H,
1997, 61, 1281–1285.
0
00
J
1
0
,2
0
7.2 Hz, H-1 ), 4.28 (dd, 1H, J5a00,400 5.6, J5a00,5b00 10.8 Hz, H-5b ),
6. Kuszmann, J.; Meggyes, G.; Boros, S. Carbohydr. Res. 2005, 340, 1739–1749.
00
4
.24 (ddd, 1H, J
3
00,200 = J
3
00,400 8.8 Hz, H-4 ), 4.14 (d, 1H, J1,2 7.2 Hz,
7. (a) Philipp, B.; Nehls, I.; Wagenknecht, W.; Schnabelrauch, M. Carbohydr. Res.
1987, 164, 107–116; (b) Tihlárik, K.; Lattová, E. Chem. Papers 1991, 45, 547–
0
H-1), 4.08 (dd, 1H, J5a
0
,4
0
5.2, J5a
0
,5b
0
11.6 Hz, H-5a ), 4.03 (dd, 1H,
552.
0
J
5a,4 5.2, J5a,5b 11.6 Hz, H-5a), 3.69 and 3.67 (m, 2H, H-4, H-4 ),
00,400 8.8 Hz, H-3 ), 3.50 (s, 3H, OMe), 3.46 (t,
H, H-3, H-3 ), 3.40 (dd, 1H, J5b00,400 9.0 Hz, H-5b ), 3.39 and 3.36
m, 2H, H-5b, H-5b ), 3.32 and 3.28 (dd, 2H, H-2 , H-2 ), 3.21 (dd,
H, J2,3 8.8 Hz, H-2); C NMR (100 MHz, MeOD) see Table 1. ESI-
TOFMS: m/z = 547.09 [M+K] calcd. 547.07.
8. Richter, A.; Klemm, D. Cellulose 2003, 10, 133–138.
0
0
3
2
(
.54 (t, 1H, J
3
0
00,200 = J
3
9. (a) Grindley, B. Adv. Carbohydr. Chem. Biochem 1998, 53, 17–142; (b) Guilbert,
B.; Davis, N. J.; Pearce, M.; Aplin, R. T.; Flitsch, S. Tetrahedron: Asymmetry 1994,
00
5
, 2163–2178.
0. Helm, R. F.; Ralph, J.; Anderson, L. J. Org. Chem. 1991, 56, 7015–7021.
11. Nilsson, M.; Westman, J.; Svahn, C.-M. J. Carbohydr. Chem. 1993, 12, 23–313.
0
0
00
1
1
3
1
1
2. Tadeo, K.; Ohguchi, Y.; Hasegawa, R.; Kitamura, S. Carbohydr. Res. 1995, 278,
01–313.
3. Ziser, L.; Withers, S. G. Carbohydr. Res. 1994, 265, 9–17.
3
1
Acknowledgments
14. Vršanská, M.; Nerinckx, W.; Claeyssens, M.; Biely, P. Carbohydr. Res. 2008, 343,
41–548.
5. Zhao, Y.; Chany, C. J., II; Sims, P. F. G.; Sinnott, M. L. J. Biotechnol. 1997, 57, 181–
90.
5
1
Authors are grateful to Daniel Kolarich and Martin Pabst for
providing the MS data. Financial support by the Austrian Chris-
tian-Doppler-Research Society in the framework of the CD-Labora-
tory ‘Pulp Reactivity’ and the competence centre WOOD Kplus is
gratefully acknowledged.
1
16. Zamyatina, A.; Gronow, S.; Puchberger, M.; Graziani, A.; Hofinger, A.; Kosma, P.
Carbohydr. Res. 2003, 338, 2571–2589.
1
1
1
2
2
7. Whistler, R. L.; Bachrach, J.; Tu, C.-C. J. Am. Chem. Soc. 1952, 74, 3059–3060.
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1. Bruker programs: SMART, version 5.629; SAINT, version 6.45; SADABS, version
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