Crystal and molecular structure of methyl 4-O-methyl-β-D-glucopyranosyl-(1→4)-β-D-glucopyranoside

Article abstract of DOI:10.1016/S0008-6215(01)00299-3

The cellulose model compound methyl 4-O-methyl-β-D-glucopyranosyl-(1→4)-β-D-glucopyranoside (6) was synthesised in high overall yield from methyl β-D-cellobioside. The compound was crystallised from methanol to give colourless prisms, and the crystal structure was determined. The monoclinic space group is P2₁ with Z = 2 and unit cell parameters a = 6.6060 (13), b = 14.074 (3), c = 9.3180 (19) A, β = 108.95(3)°. The structure was solved by direct methods and refined to R = 0.0286 for 2528 reflections. Both glucopyranoses occur in the ⁴C₁ chair conformation with endocyclic bond angles in the range of standard values. The relative orientation of both units described by the interglycosidic torsional angles [φ (O-5′-C-1′-O-4-C-4) -89.1°, φ (C-1′-O-4-C-4-C-5) -152.0°] is responsible for the very flat shape of the molecule and is similar to those found in other cellodextrins. Different rotamers at the exocyclic hydroxymethyl group for both units are present. The hydroxymethyl group of the terminal glucose moiety displays a gauche-trans orientation, whereas the side chain of the reducing unit occurs in a gauche-gauche conformation. The solid state ¹³C NMR spectrum of compound 6 exhibits all 14 carbon resonances. By using different cross polarisation times, the resonances of the two methyl groups and C-6 carbons can easily be distinguished. Distinct differences of the C-1 and C-4 chemical shifts in the solid and liquid states are found.

Full text of DOI:10.1016/S0008-6215(01)00299-3

Carbohydrate Research 337 (2002) 161–166
www.elsevier.com/locate/carres
Crystal and molecular structure of methyl
4-O-methyl-b- -glucopyranosyl-(1“4)-b- -glucopyranoside
D
D
Iain D. Mackie,a Ju¨rgen Ro¨hrling,b Robert O. Gould,a Jutta Pauli,c Christian Ja¨ger,c
Malcolm Walkinshaw,d Antje Potthast,b Thomas Rosenau,b Paul Kosmab,*
aDepartment of Chemistry, Uni6ersity of Edinburgh, Edinburgh EH9 3JJ, UK
bChristian Doppler-Laboratory, Institute of Chemistry, Uni6ersity of Agricultural Sciences, Muthgasse 18, A-1190 Vienna, Austria
cLaboratorium I.31, Federal Institution for Material Science and Testing, Richard-Willstaetter-Strasse 11, D-12489 Berlin, Germany
dInstitute of Cell and Molecular Biology, Uni6ersity of Edinburgh, Edinburgh EH9 3JR, UK
Received 30 April 2001; received in revised form 7 November 2001; accepted 7 November 2001
Abstract
The cellulose model compound methyl 4-O-methyl-b-
overall yield from methyl b- -cellobioside. The compound was crystallised from methanol to give colourless prisms, and the
crystal structure was determined. The monoclinic space group is P21 with Z=2 and unit cell parameters a=6.6060 (13),
D
-glucopyranosyl-(1“4)-b-
D-glucopyranoside (6) was synthesised in high
D
,
b=14.074 (3), c=9.3180 (19) A, i=108.95(3)°. The structure was solved by direct methods and refined to R=0.0286 for 2528
reflections. Both glucopyranoses occur in the C1 chair conformation with endocyclic bond angles in the range of standard values.
4
The relative orientation of both units described by the interglycosidic torsional angles [ƒ (O-5%ꢀC-1%ꢀO-4ꢀC-4) −89.1°, €
(C-1%ꢀO-4ꢀC-4ꢀC-5) −152.0°] is responsible for the very flat shape of the molecule and is similar to those found in other
cellodextrins. Different rotamers at the exocyclic hydroxymethyl group for both units are present. The hydroxymethyl group of
the terminal glucose moiety displays a gauche–trans orientation, whereas the side chain of the reducing unit occurs in a
gauche–gauche conformation. The solid state 13C NMR spectrum of compound 6 exhibits all 14 carbon resonances. By using
different cross polarisation times, the resonances of the two methyl groups and C-6 carbons can easily be distinguished. Distinct
differences of the C-1 and C-4 chemical shifts in the solid and liquid states are found. © 2002 Elsevier Science Ltd. All rights
reserved.
Keywords: Crystal structure; Cellulose; Methyl cellobioside; Solid state NMR
determined and compared with the data obtained from
cellulose II.7,8 In addition, model compounds have been
used in conformational studies employing NMR spec-
troscopy or MD simulations.9,10 For ongoing structural
studies of cellulosic substrates, a 4%-O-methyl substi-
tuted methyl cellobioside was prepared. Herein we re-
port on the chemical synthesis of methyl 4-O-
1. Introduction
X-ray diffraction methods have been used intensively
to study the spatial arrangements and intricate hydro-
gen bonding patterns of cellulosic chains.1 To comple-
ment the fibre diffraction techniques and clarify the
ambiguities pertaining to the conformational orienta-
tion of the hydroxymethyl groups and the packing
mode of cellulose II, various model glucosides have
been investigated. Thus, the crystal and molecular
structures of compounds such as cellobiose,2 a cel-
lobiose complex with NaI,3 methyl b-cellobioside,4
methyl b-cellotrioside5 and b-cellotetraose6 have been
methyl-b-
D
-glucopyranosyl-(1“4)-b-D -glucopyran-
oside (6) and the determination of the crystal and
molecular structure.
2. Results and discussion
For the synthesis of model compound 6, known
methyl b-cellobioside 111 was selectively protected by
reaction with a,a-dimethoxytoluene under acid catalysis
* Corresponding author. Tel.: +43-1-360066055; fax: +
43-1-360066059.
E-mail address: pkosma@edv2.boku.ac.at (P. Kosma).
0008-6215/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0008-6215(01)00299-3

162
I.D. Mackie et al. / Carbohydrate Research 337 (2002) 161–166
4 reacted smoothly with methyl iodide–sodium hydride
to produce the 4%-O-methyl ether derivative 5 in 95%
yield (Scheme 1). Finally, the benzyl groups where
removed by hydrogenolysis with 10% Pd–C as catalyst
to give the title compound 6 in 97% yield, which readily
crystallised from methanol.
in anhydrous N,N-dimethylformamide to give the cor-
responding 4%,6%-O-benzylidene compound 2,12 which
was per-O-benzylated and subsequently treated with
sodium cyanoborohydride–hydrogen chloride in dry
THF to afford compound 4 in 77% yield.13 Compound
Unambiguous 13C NMR assignments of the spectrum
of 6, recorded in D2O, were achieved via HMBC-mea-
surements, which allowed the differentiation of the two
methyl groups. The spectral data were in good agree-
ment with those of other cellodextrins.14 Compared to
substitution by a b-glucopyranosyl residue, methyl
ether substitution at C-4% resulted in pronounced
downfield-shifts of the 13C NMR signals for C-4% (79.94
ppm) and C-3% (75.96 ppm), respectively.
Crystals were obtained from a saturated solution of 6
(5 mg) in MeOH (1 mL) at 40 °C and gradual cooling
to room temperature. A colorless prism (0.55×0.35×
0.2 mm) was selected for the measurements. The crystal
data and details of the intensity-data collection are
given in Table 1. X-ray diffraction data were collected
at 220 K using a ꢀ/2q scan mode. Unit-cell dimensions
were obtained by a least-squares fit. The structure was
solved by direct methods with SHELXL-97 and refined to
a final R=0.0286 for 2528 reflections (Table 2). The
conformation of the molecule and the numbering of
atoms is shown in Fig. 1.
Scheme 1.
Table 1
Crystallographic data for disaccharide 6
Empirical formula
Formula weight
C14H26O11
370.36
Crystal dimensions (mm) 0.55×0.35×0.2
Crystal system
Space group
Temperature (K)
monoclinic
P21
220(2)
,
Wavelength (A)
Unit cell dimensions
1.54178
Molecular geometry.—Both glucopyranosyl units oc-
cur in the C1 chair conformation with endocyclic bond
angles and bond lengths in the range of standard values
(Tables 3 and 4). The observed values match those of
cellobiose2 and of methyl b-cellobioside, which was
crystallised as a 1:1 complex with methanol.4
4
,
a (A)
6.6060 (13)
14.074 (3)
9.3180(19)
108.95(3)
819.4(3)
2
,
b (A)
,
c (A)
i (°)
3
,
Cell volume (A )
Z
The effect of methyl substitution at O-4% leads to a
slight increase in the exocyclic C-4%ꢀC-3%ꢀO-3% bond
angle (112.54°) compared to the values found for cel-
lobiose (108.1°) and methyl b-cellobioside (110.2°). The
interglycosidic torsional angles [ƒ (O-5%ꢀC-1%ꢀO-4ꢀC-4)
−89.1°, € (C-1%ꢀO-4ꢀC-4ꢀC-5) −152.0°] are in close
agreement with those found in other cellodextrins such
as methyl b-cellotrioside.5 Different rotamers at the
exocyclic hydroxymethyl group for both units are
present. Whereas the hydroxymethyl group of the ter-
minal glucose moiety displays a clear gt conformation
(as is thought to occur in cellulose II), that of the
reducing unit occurs in a gg orientation.
The packing of the molecules in the unit cell is shown
in Fig. 2. The disaccharides align in a near perpendicu-
lar relative orientation. Intermolecular hydrogen bonds
extend from HO-2 to O-2% and from HO-6 to O-2,
leading to the gg orientation of the primary hydroxyl
group at C-6 of the reducing glucopyranosyl unit.
Intramolecular hydrogen-bonds extend from O-
F(000)
396
1.501
Calculated density
(g/cm3)
Absorption coefficient
11.28
(cm−1
)
q Range for data
collection
5.02–70.08
Index ranges
−85h57, −125k517,
−45l511
32 (20.5BqB21.5°)
2712
Reflections for cell
Reflections collected
Independent reflections
Refinement method
2566 (Rint=0.0132)
full-matrix least-squares on F2
Data/restraints/parameters 2566/1/331
Goodness-of-fit on F2
Conventional R
[F\4|(F)]
0.877
R1=0.0286 for 2528 data
Weighted R (F2 and all
data)
wR2=0.0915
−0.11(16)
0.036(2)
Absolute structure
parameter
Extinction coefficient
,
3(H)ꢀO-5% with a distance of 2.82 A and from O-
,
3(H)ꢀO-6% with a distance of 3.16 A.

I.D. Mackie et al. / Carbohydrate Research 337 (2002) 161–166
163
Table 2
Table 3
Atomic coordinates (×104) and equivalent isotropic displace-
ment parameters (A2×103) for disaccharide 6
Selected bond-lengths and their standard deviation for non-
hydrogen atoms
,
Atom
x
y
z
Ueq
Bond lengths (A)
C-1
7102(3)
6714(3)
8574(5)
5044(3)
4453(3)
5314(3)
3254(3)
6237(3)
7020(2)
8186(3)
7609(2)
8977(3)
7475(3)
5554(3)
6731(3)
7808(2)
5093(3)
6081(3)
3694(3)
1853(2)
1987(4)
2857(3)
4569(2)
1809(4)
1015(3)
3238(2)
3494(1)
3457(2)
3395(2)
4369(1)
3050(2)
3103(2)
2052(2)
1818(1)
1946(2)
2259(1)
938(2)
349(1)
1445(2)
827(2)
68(1)
414(2)
3645(2)
2140(2)
1693(3)
4015(2)
3899(2)
5606(2)
5771(2)
5872(2)
7462(2)
5328(2)
3787(2)
5352(2)
4306(2)
8089(2)
9446(2)
9001(2)
10114(2)
11389(2)
10455(2)
10700(2)
12235(3)
9125(2)
8619(2)
9522(2)
8267(2)
25(1)
32(1)
42(1)
25(1)
35(1)
27(1)
41(1)
24(1)
24(1)
23(1)
25(1)
28(1)
36(1)
22(1)
22(1)
26(1)
23(1)
28(1)
22(1)
29(1)
43(1)
22(1)
24(1)
29(1)
32(1)
C-1ꢀO-1
C-1ꢀO-5
C-1ꢀC-2
O-1ꢀC-1M
C-2ꢀO-2
C-2ꢀC-3
C-3ꢀO-3
C-3ꢀC-4
C-4ꢀO-4
C-4ꢀC-5
O-4ꢀC-1%
C-5ꢀO-5
C-5ꢀC-6
C-6ꢀO-6
C-1%ꢀO-5%
C-1%ꢀC-2%
C-2%ꢀO-2%
C-2%ꢀC-3%
C-3%ꢀO-3%
C-3%ꢀC-4%
C-4%ꢀO-4%
C-4%ꢀC-5%
O-4%ꢀC-4%M
C-5%ꢀO-5%
C-5%ꢀC-6%
C-6%ꢀO-6%
1.388(2)
1.414(3)
1.524(3)
1.421(3)
1.420(3)
1.514(3)
1.420(3)
1.519(3)
1.440(2)
1.536(3)
1.386(2)
1.430(2)
1.509(3)
1.412(3)
1.415(3)
1.524(3)
1.417(3)
1.528(3)
1.418(2)
1.525(3)
1.434(2)
1.528(3)
1.417(3)
1.435(2)
1.510(3)
1.411(3)
O-1
C-1M
C-2
O-2
C-3
O-3
C-4
O-4
C-5
O-5
C-6
O-6
C-1%
C-2%
O-2%
C-3%
O-3%
C-4%
O-4%
C-4%M
C-5%
O-5%
C-6%
O-6%
−171(1)
1185(2)
767(1)
628(3)
1874(2)
2200(1)
2743(2)
3358(1)
Ueq is defined as one third of the trace of the orthogonalised
Uij tensor.
Table 4
Selected geometric and spectroscopic parameters for cel-
lobiose, methyl cellobioside and disaccharide 6
Parameter
Cello-
biose2
Me cello-
bioside4 a
6
Selected bond angles (°)
C-1%ꢀO-4ꢀC-4
116.1
108.1
115.8
113.1
110.2
117.0
113.1
112.5
C-1ꢀO-1ꢀOMe
C-4%ꢀC-3%ꢀO-3%
Fig. 1. Perspective view and atom labelling of methyl 4%-O-
Linkage torsion angles (°)
ƒ (O-5%ꢀC-1%ꢀO-4ꢀC-4) −76.3 −88.9
„ (C-1%ꢀO-4ꢀC-4ꢀC-5) −132.3 −160.7
methyl b-
D
-glucopyranosyl-(1“4)-b-D-glucopyranoside 6.
−89.1
−152.0
The solid state 13C NMR spectrum using cross polar-
isation and rotation at the magic angle spinning (CP-
MAS, Fig. 3) displays all 14 expected carbon
resonances. Furthermore, the linewidth of 18 Hz is
extraordinarily narrow and TPPM decoupling is re-
quired. Only one of the C-6 carbons has a rather broad
resonance (56 Hz) which is subject to further investiga-
tions. As indicated in Fig. 3 and Table 4, the following
lines can be assigned unambiguously: C-1,1% at 105.3 and
104.9 ppm, C-4,4% at 83.6 and 80.7 ppm, C-6,6% signals
Hydroxymethyl group torsion angles (°)
 (O-5ꢀC-5ꢀC-6ꢀO-6)
(O-5%ꢀC-5%ꢀC-6%ꢀO-6%)
+65.5 −55.1
+48.7 +52.4
−54.3
+59.0
Chemical shift (ppm) for carbon atom
C-1 or C-1%
C-4 or C-4%
C-6 or C-6%
104.9
84.9
106.5
85.5
105.3/104.9
83.6/80.7
63.3/59.9
a The compound crystallised as solvate complex with
methanol.

164
I.D. Mackie et al. / Carbohydrate Research 337 (2002) 161–166
Fig. 2. View of packing mode and unit cell of compound 6. Hydrogen bonds are drawn in dashed lines.
at 63.3 and 59.9 ppm and ꢀOCH3 at 63.8 and 58.4 ppm.
The discrimination between C-6 and ꢀOCH3 resonances
can easily be achieved by comparing the CPMAS spec-
tra with 100 ms and 1 ms cross polarisation times. For
the shorter cross polarisation time, the ꢀOCH3 signals
have only about 50% intensity compared to C-6 be-
cause of the methyl group rotation. The observed
chemical shift difference between the C-6 and C-6%
signals would be consistent with the results by Horii,
indicating a range of 60–62 ppm for CH2OH carbons
in the gauche–gauche orientation versus 62.5–64.5
ppm for those occurring in the gauche–trans conforma-
tion.15 It is worth noting that substantial differences of
the chemical shifts for the carbons C-1 and C-4 are
observed in the liquid and solid state NMR spectra.
The chemical shifts of carbons involved in the glyco-
sidic linkage are sensitive to conformational changes,
which in contrast to the solid state become motionally
averaged in solution. Further NMR experiments with
labelled model compounds will be performed in order
to obtain unambiguous assignments for all carbons and
thus provide a reliable model system for the interpreta-
tion of solid state NMR-spectroscopic studies of native
and regenerated celluloses.16
scribed recently.17 X-ray diffraction data were collected
with a Stoe Stadi-4 diffractometer.
The NMR measurements were recorded on a Bruker
DMX400 spectrometer, using a double channel CP-
MAS probehead. The spinning frequency of the 4 mm
ZrO2-CRAMPS-rotor was 12,500 Hz and was stabilised
to 92 Hz. The 13C CPMAS spectra were acquired at a
radio frequency of 100.3 MHz. The 90° proton pulse
was set to 2.5 ms, a 13C B1-field of 50 kHz during the
ramped (50% ramp on proton channel) CP sequence
with a mixing time of 1 ms or 100 ms were used. The
TPPM-sequence18 with a flip angle of 168.5° (pulse
length 4.5 ms) and a phase shift of 10° was applied to
decouple the protons during the acquisition time.
Methyl 4,6-O-benzylidene-i-
D
-glucopyranosyl-(1“
4)-i- -glucopyranoside (2).—Methyl cellobioside
D
1
3. Experimental
General methods.—Synthetic methods were as de-
Fig. 3. CPMAS NMR spectrum of disaccharide 6.

I.D. Mackie et al. / Carbohydrate Research 337 (2002) 161–166
165
(1.00 g, 2.81 mmol), a,a-dimethoxytoluene (0.63 mL,
4.21 mmol), p-toluene–sulfonic acid (0.05 g) and anhyd
DMF (50 mL) were stirred at rt for 3 days. A second
portion of a,a-dimethoxytoluene (0.42 mL, 2.81 mmol)
was added and the mixture was heated to 50 °C under
reduced pressure (50 mbar) for 2 h. After addition of
triethylamine (3 mL), the reaction mixture was evapo-
rated. Column chromatography of the residue (10:1
EtOAc–MeOH) gave 2 as colourless crystals (0.782 g,
63%), mp 150–152 °C, lit. 151–152 °C (EtOH);12 [h]D20
−32° (c 1.2, MeOH), lit. [h]2D0 −37° (c 1.9, DMF).12
1H NMR (CD3OD): l 7.35–7.58 (m, 5 H, Ph), 5.63 (s,
1 H, CHPh), 4.61 (d, 1 H, J1%,2% 7.8 Hz, H-1%), 4.35 (dd,
1 H, J5%,6b% 3.7, J6a%,6b% 10.2 Hz, H-6b%), 4.25 (d, 1 H, J1,2
7.8 Hz, H-1), 3.90–3.96 (m, 1 H, H-6b), 3.88 (dd, 1 H,
J5%,6a% 3.9 Hz, H-6a%), 3.83 (dd, 1 H, J3,4 9.7, J4,5 9.7 Hz,
H-4), 3.60–3.75 (m, 2 H, H-5, H-3%), 3.50–3.57 (m, 5
H, H-5%, 1-OMe, H-3, H-4%), 3.30–3.50 (m, 2 H, H-6a,
H-2%) and 3.28 (dd, 1 H, J2,3 8.3 Hz, H-2).
CHCl3).13 1H NMR data (CDCl3): l 7.19–7.36 (m, 30
H, 6×Ph), 4.93 (d, 1 H, J 11.0 Hz, CH2Ph), 4.67–4.87
(m, 7 H, CH2Ph), 4.59 (d, 1 H, J 12.1 Hz, CH2Ph), 4.47
(d, 1 H, J1%,2% 7.2 Hz, H-1%), 4.40–4.46 (m, 3 H, CH2Ph),
4.27 (d, 1 H, J1,2 7.7 Hz, H-1), 3.96 (dd, 1 H, J3,4 9.1,
J4,5 9.1 Hz, H-4), 3.82 (dd, 1 H, J5,6b 4.2, J6a,6b 11.0 Hz,
H-6b), 3.70 (dd, 1 H, J5,6a 2.2, Hz, H-6a), 3.46–3.64 (m,
7 H, H-6a%, H-6b%, 1-OMe, H-4%, H-3), 3.29–3.41 (m, 4
H, H-2, H-5, H-3%, H-2%), 3.20–3.28 (m, 1 H, H-5%) and
2.86 (d, 1 H, J4%,OH 1.5 Hz, OH).
Methyl 2,3,6-tri-O-benzyl-4-O-methyl-i-D-glucopy-
ranosyl-(1“4)-2,3,6-tri-O-benzyl-i- -glucopyranoside
D
(5).—Sodium hydride (0.337 g, 14.1 mmol) was added
to a solution of 4 (6.22 g, 7.03 mmol) in dry THF (150
mL). The mixture was stirred under argon for 1 h.
Methyl iodide (2.19 mL, 35.1 mmol) was added, and
the mixture was stirred overnight at rt. The reaction
mixture was poured onto aq satd NH4Cl and extracted
with EtOAc (100 mL). The organic layer was dried over
MgSO4 and concentrated. Chromatography of the
crude product on silica gel (toluene“7:1 toluene–
EtOAc) gave 5 as colourless syrup (5.99 g, 95%); [h]D20
Methyl 2,3-di-O-benzyl-4,6-O-benzylidene-i-
D-glu-
copyranosyl-(1“4)-2,3,6-tri-O-benzyl-i- -glucopy-
D
ranoside (3).—Sodium hydride (3.83 g, 160 mmol) was
added to a solution of 2 (7.10 g, 16.0 mmol) in anhyd
DMF (150 mL). The mixture was stirred under argon
for 1 h. Benzyl bromide (19.0 mL, 160 mmol) was
added and the mixture was stirred overnight at rt. The
solution was poured onto satd aq NH4Cl and extracted
with EtOAc. The combined organic layers were dried
over MgSO4 and evaporated. Chromatography (tolu-
ene“7:1 toluene–EtOAc) of the crude product gave 3
as colourless crystals (9.95 g, 71%), mp 144–146 °C
(EtOH), lit. 143–145 °C (4:1 hexane–EtOAc);13 [h]D20
1
+23° (c 0.5, CHCl3). H NMR (CDCl3): l 7.16–7.35
(m, 30 H, 6×Ph), 5.03 (d, 1 H, J 11.5 Hz, CH2),
4.65–4.85 (m, 9 H, CH2), 4.58 (d, 1 H, J 12.1 Hz, CH2),
4.46 (d, 1 H, J1%,2% 7.1 Hz, H-1%), 4.43 (d, 1 H, J 11.5 Hz,
CH2), 4.27 (d, 1 H, J1,2 7.7 Hz, H-1), 3.99 (dd, 1 H, J3,4
9.3, J4,5 9.3 Hz, H-4), 3.81 (dd, 1 H, J5,6a 4.2, J6a,6b 11.0
Hz, H-6a), 3.64–3.72 (m, 2 H, H-6b, H-6a%), 3.49–3.60
(m, 5 H, H-3, 1-OMe, H-6b%), 3.47 (s, 3 H, 4%-OMe),
3.28–3.45 (m, 5 H, H-3%, H-2, H-5, H-4%, H-2%) and
3.15–3.20 (m, 1 H, H-5%). Anal. Calcd for C55H62O11:
C, 73.47; H, 6.95. Found: C, 73.21; H, 6.80.
+1° (c 0.9, CHCl3), lit. [h]2D0 +4° (c 2.1, CHCl3).13 1
H
NMR data (CDCl3): l 7.22–7.50 (m, 30 H, 6×Ph),
5.48 (s, 1 H, CHPh), 4.68–4.91 (m, 8 H, CH2Ph), 4.58
(d, 1 H, J 12.1 Hz, CH2Ph), 4.53 (d, 1 H, J1%,2% 7.7 Hz,
H-1%), 4.38 (d, 1 H, J 12.1 Hz, CH2Ph), 4.28 (d, 1 H,
J1,2 7.6 Hz, H-1), 3.82 (dd, 1 H, J5%,6b% 5.1, J6a%,6b% 10.6
Hz, H-6b%), 3.98 (dd, 1 H, J3,4 9.2, J4,5 9.2 Hz, H-4),
3.83 (dd, 1 H, J5,6b 3.7, J6a,6b 10.8 Hz, H-6b), 3.67 (dd,
1 H, J5,6a 1.2 Hz, H-6a), 3.30–3.61 (m, 10 H, H-3%,
H-4%, 1-OMe, H-3, H-6a%, H-2, H-2%, H-5) and 3.09–
3.18 (m, 1 H, H-5%).
Methyl 4-O-methyl-i-
D
-glucopyranosyl-(1“4)-i-D-
glucopyranoside (6).—A solution of 5 (5.90 g, 6.56
mmol) in dry MeOH (100 mL) was hydrogenated at rt
in the presence of 10% Pd–C (0.25 g) for 15 h at
atmospheric pressure. The catalyst was removed by
filtration, and the filtrate was concentrated to yield 6 as
colourless crystals (2.35 g, 97%); mp 196–198 °C
1
(MeOH); [h]2D0 −11° (c 0.4, water). H NMR (D2O): l
4.47 (d, 1 H, J1%,2% 7.9 Hz, H-1%), 4.39 (d, 1 H, J1,2 8.0
Hz, H-1), 3.98 (dd, 1 H, J5,6a 1.8, J6a,6b 12.3 Hz, H-6a),
3.90 (dd, 1 H, J5%,6a% 2.3 Hz, H-6a%), 3.89 (dd, 1 H, J5,6b
4.6 Hz, H-6b), 3.73 (dd, 1 H, J5%,6b% 5.3, J6a%,6b% 12.4 Hz,
H-6b%), 3.56–3.63 (m, 7 H, H-5, H-4, H-3, H-3%, 1-
OMe), 3.55 (s, 3 H, 4%-OMe), 3.47 (ddd, 1 H, J4%,5% 9.5
Hz, H-5%), 3.25–3.40 (m, 2 H, H-2%, H-2), 3.22 (dd, 1 H,
J3%,4% 9.5 Hz, H-4%); 13C NMR (D2O): l 103.87 (C-1),
103.27 (C-1%), 79.94 (C-4%), 79.42 (C-4), 75.96 (C-3%),
75.79 (C-5), 75.56 (C-5%), 75.11 (C-3), 73.97 (C-2%), 73.68
(C-2), 61.11 (C-6%), 60.83 (C-6, 4%-Me) and 58.02 (1-
Me). IR (KBr): 3440 (b), 2916 (s), 2883 (s), 1620 (w),
1452 (m), 1451 (m), 1363 (m), 1165 (s), 1107 (s), 1035
(s), 993 (s). Anal. Calcd for C14H26O11: C, 45.40; H,
7.08. Found: C, 45.34; H, 6.80.
Methyl 2,3,6-tri-O-benzyl-i-
D
-glucopyranosyl-(1“
4)-2,3,6-tri-O-benzyl-i- -glucopyranoside (4).—A so-
D
lution of HCl in anhyd Et2O (2.5 M) was added
dropwise to a solution of 3 (4.72 g, 5.35 mmol) and
NaCNBH3 (3.36 g, 53.5 mmol) in dry THF (100 mL)
,
containing powdered 3 A molecular sieves, until the
evolution of gas ceased. The molecular sieves were
filtered off after 30 min, and EtOAc was added. The
mixture was extracted twice with satd NaHCO3 and
once with brine. The organic layer was dried over
MgSO4 and evaporated. Column chromatography (9:1
toluene–EtOAc) yielded a 4 as colourless syrup (3.63 g,
77%); [h]2D0 +8° (c 0.4, CHCl3), lit. [h]2D0 +7° (c 1.5,

166
I.D. Mackie et al. / Carbohydrate Research 337 (2002) 161–166
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6. (a) Geßler, K.; Krauß, N.; Steiner, T.; Betzel, C.;
Sandmann, C.; Saenger, W. Science 1994, 266, 1027–
1029;
4. Supplementary material
The data were deposited at the Cambridge Structural
database (Accession number CCDC 172127). Copies of
this information can be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (Fax: +44-1223-336033: e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
,
(b) Raymond, S.; Henrissat, B.; Tran Qui, D.; Kvick, A.;
Chanzy, H. Macromolecules 1995, 28, 2096–2100.
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Technical assistance by Maria Hobel is gratefully
acknowledged. The authors also thank Dr Andreas
Hofinger and Dr Michael Puchberger for recording
NMR spectra.
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