Stereoselective synthesis of the 3-aminopropyl glycosides of α-D-xyl-(1→3)-β-D-glc and α-D-xyl-(1→3)-α-D- xyl-(1→3)-β-D-glc and of their corresponding N-octanoyl derivatives

Article abstract of DOI:10.1055/s-2007-990784

The stereoselective synthesis of the spacer-armed disaccharide α-D-Xyl-(1→3)-β-D-Glc-O-(CH₂)₃NH ₂ and trisaccharide α-D-Xyl-(1→3)-α-D-Xyl-(1→3) -β-D-Glc-O-(CH₂)₃NH₂, as well as of their N-octanoyl derivatives, was performed for their subsequent use as acceptors and reference samples in xylosyltransferase assays. These structures are found as O-linked glycans on epidermal growth factor (EGF) domains of several blood-clotting factors and Notch. The target products were prepared by glycosylation with a 3-O-acetylated xylosyl donor that was previously found to be an effective α-xylosylating agent. However, in this paper we show that the structure of the glycosyl acceptor could influence the stereochemical results of the glycosylation and even lead to reversed stereoselectivity in the case of one acceptor. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2007-990784

PAPER
3147
Stereoselective Synthesis of the 3-Aminopropyl Glycosides of a-D-Xyl-(1→3)-
b-D-Glc and a-D-Xyl-(1→3)-a-D-Xyl-(1→3)-b-D-Glc and of Their Correspon-
ding N-Octanoyl Derivatives
S
tereoselective
Sy
a
nthesis of
3
d
-Aminoprop
i
m
oside
s
Krylov,a Nadezhda Ustyuzhanina,b Alexey Grachev,b Hans Bakker,c Nikolay Nifantiev*b
a
Higher Chemical College, Russian Academy of Sciences, Miusskaya Square 9, 125047 Moscow, Russian Federation
Laboratory of Glycoconjugate Chemistry, N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
Leninsky Prospect 47, 119991 Moscow, Russian Federation
b
Fax +7(495)1358784; E-mail: nen@ioc.ac.ru
Hannover Medical School (MHH), Department of Cellular Chemistry OE4330, Carl-Neuberg-Straße 1, 30625 Hannover, Germany
c
Received 1 June 2007; revised 8 June 2007
OH
O
Abstract: The stereoselective synthesis of the spacer-armed disac-
charide a-D-Xyl-(1→3)-b-D-Glc-O-(CH2)3NH2 and trisaccharide a-
D-Xyl-(1→3)-a-D-Xyl-(1→3)-b-D-Glc-O-(CH2)3NH2, as well as of
their N-octanoyl derivatives, was performed for their subsequent
use as acceptors and reference samples in xylosyltransferase assays.
These structures are found as O-linked glycans on epidermal growth
factor (EGF) domains of several blood-clotting factors and Notch.
The target products were prepared by glycosylation with a 3-O-
acetylated xylosyl donor that was previously found to be an effec-
tive a-xylosylating agent. However, in this paper we show that the
structure of the glycosyl acceptor could influence the stereochemi-
cal results of the glycosylation and even lead to reversed stereose-
lectivity in the case of one acceptor.
HO
HO
O
NHR
O
OH
HO
HO
O
1
2
R = H
R = COC7H15
OH
O
O
HO
HO
HO
O
NHR
O
OH
HO
HO
O
HO
O
3
4
R = H
R = COC7H15
Key words: carbohydrates, glycosylations, stereoselectivity, a-xy-
losylations, remote participation
Figure 1 Oligosaccharide derivatives synthesized
the corresponding a- and b-isomers that were difficult to
In 1996, a novel enzyme able to transfer xylose to the dis-
accharide acceptor a-D-Xyl-(1→3)-b-D-Glc and, thus,
form trisaccharide chain a-D-Xyl-(1→3)-a-D-Xyl-
(1→3)-b-D-Glc was discovered in human cells.1 Both the
disaccharide and trisaccharide carbohydrate chains were
found in bovine and human blood-clotting factors VII, IX,
and protein Z.2 Little is known about the functions of these
oligosaccharides, but it was suggested that they may serve
as regulators of coagulation activity.3 Additionally, these
O-linked glycans were linked to EGF repeats of the Notch
receptor, where they might have a similar function as O-
fucose-linked glycans.4
separate.
We describe here the synthesis of oligosaccharide deriva-
tives 1–4 using 3-O-acetyl-2,4-di-O-benzyl-D-xylopyra-
nosyl 2,2,2-trichloroacetimidate (5). The acetyl group in
this compound affords temporary protection of the hy-
droxy group at C-3, permitting further elongation of the
appropriate oligosaccharide chain by 3-O-a-D-xylosyla-
tion. We have also used 3-O-acetylated donor 5 to explore
the remote a-stereocontrolling effect of an O-acetyl
group.6–8 This effect arises from the anchimeric participa-
tion of the 3-O-acetyl group resulting in the formation of
stabilized cation II. The nucleophilic attack of II is fa-
vored from the a-side, whereas attack of the nonstabilized
cation I is possible from both the a- and b-sides
(Scheme 1).
In this paper, we report the stereoselective synthesis of
oligosaccharides 1 and 3 and their corresponding N-oc-
tanoyl derivatives 2 and 4 (Figure 1) for their further ap-
plication as acceptor substrates and reference samples in
xylosyltransferase assays. In addition to compounds 2 and
4, other conjugates could be prepared from amines 1 and
3 and used as probes for biochemical investigations.
For the synthesis of trichloroacetimidate 5, allyl a-D-xy-
lopyranoside (6)9 was first regioselectively transformed
into the 2,4-di-O-benzylated derivative 7;5 then, 3-O-
acetylation of 7 gave the fully protected allyl xylopyrano-
side 8 (Scheme 2). The presence of the O-acetyl group at
C-3 was confirmed by the downfield shift of the H-3 sig-
Previously reported syntheses of a-D-Xyl-(1→3)-b-D-Glc
and a-D-Xyl-(1→3)-a-D-Xyl-(1→3)-b-D-Glc derivatives
entailed the use of fully benzylated mono- and di-xylosyl
donors.5 In these cases, the glycosylation reaction pro-
ceeded with low stereoselectivity and gave a mixture of
1
nal in the H NMR spectrum of 8 (d = 5.50) compared
with the data for nonacylated 7 (d = 4.06). O-
Deallylation10 of 8 with palladium(II) chloride in metha-
nol, followed by trichloroacetimidation11 of the resulting
hemiacetal using trichloroacetonitrile and 1,8-diazabicyc-
lo[5.4.0]undec-7-ene (DBU) gave xylosyl donor 5 as an
SYNTHESIS 2007, No. 20, pp 3147–3154
x
x.
x
x
.
2
0
0
7
Advanced online publication: 21.09.2007
DOI: 10.1055/s-2007-990784; Art ID: P06807SS
© Georg Thieme Verlag Stuttgart · New York

3148
V. Krylov et al.
PAPER
Me
β
+
O
+
O
O
O
BnO
AcO
O
BnO
AcO
BnO
BnO
α
O
CCl3
NH
α
BnO
BnO
5
I
II
Scheme 1 Reactive sites of the nonstabilized I and stabilized glycosyl cations II formed from xylosyl donor 5
OAc
O
OAc
O
O
O
HO
HO
BnO
RO
a
a
H
O
AcO
AcO
AcO
AcO
BnO
AcO
N
CF3
O
HO
BnO
OAll
OAll
AcO
9
AcO
O
CCl3
NH
BnO
O
Br
7
8
R = H
6
10
b
c
5
R = Ac
b
Scheme 2 Reagents and conditions: (a) 1. NaH (2 equiv), DMSO;
2. BnBr (2 equiv) (42% yield); (b) Ac2O, py (99% yield); (c) 1. PdCl2,
MeOH; 2. CCl3CN, DBU, CH2Cl2 (67% yield).
O
Ph
O
O
HO
Ph
O
O
O
R2O
OR
OR
OR1
OR1
R1 = H
R1 = Bz
13 R1 = H R2 = Bn
d
11
14 R1 = Bn R2 = H
approximately 1:1 mixture (determined by NMR spec-
troscopy) of the a- and b-isomers in a total yield of 67%.
c
12
5, e
5, e
To assemble the a-D-Xyl-(1→3)-b-D-Glc disaccharide
derivatives, the xylosylation of glucopyranosides 12 and
14 bearing a free hydroxy group at C-3 was studied first.
To prepare acceptors 12 and 14, O-acetyl-substituted glu-
copyranosyl bromide 9 was converted into b-glucopyra-
noside 10 by reaction with 3-(trifluoroacet-
amido)propanol in the presence of mercury(II) cyanide
and mercury(II) bromide (Scheme 3). Deacetylation of 10
followed by 4,6-O-benzylidenation gave diol 11. Regi-
oselective benzoylation of diol 11 using benzoyl chloride
via a stannylene acetal afforded the 2-O-benzoylated ac-
ceptor 12 in 74% yield. However, the dibutyltin oxide me-
diated benzylation of 11 using benzyl bromide in the
presence of tetrabutylammonium bromide (TBAB) was
less selective and gave the 2-O- and 3-O-benzyl-substitut-
ed monosaccharides 14 and 13 in 21 and 45% yields, re-
spectively. The structures of these benzylated products
were deduced from the 1H NMR spectroscopic data of 13
and 14 and the corresponding acetylated derivatives.
O
Ph
BnO
O
O
Ph
O
O
OR
O
O
O
OR
BnO
AcO
O
OBn
AcO
BnO
OBz
OBn
O
16
15
R = (CH2)3NHCOCF3
Scheme 3 Reagents and conditions: (a) HO(CH2)3NHCOCF3,
Hg(CN)2, HgBr2, CH2Cl2, r.t., 6 h (62% yield); (b) 1. NaOMe/MeOH,
r.t.; 2. PhCH(OMe)2, CSA, MeCN, 45 °C. (71% yield); (c) 1.
Bu2SnO, toluene, reflux; 2. BzCl, r.t., 1 h (74% yield); (d) 1. Bu2SnO,
toluene, reflux; 2. BnBr, TBAB, 60 °C, 5 h (45% yield of 13, 21%
yield of 14); (e) TMSOTf, CH2Cl2, –40 °C, 50 min (65% yield of 15,
72% yield of 16)
Table 1 Study of the Stereoselectivity of the Coupling of 5 and 17
Entry Solvent
Promotera
Temp
(°C)
Ratio
(a/b)
Total yield
(%)
1
2
3
4
5
CH2Cl2
CH2Cl2
CH2Cl2
TMSOTf
TMSOTf
TMSOTf
20
–40
–90
–40
–40
1:1.4
4.2:1
9:1
72
87
86
61
92
The xylosylations of both acceptors 12 and 14 with donor
5 gave unexpected stereochemical results. Thus, the cou-
pling of compounds 12 and 5 in dichloromethane at –40
°C promoted by trimethylsilyl trifluoromethanesulfonate
(TMSOTf) resulted in the predominant formation of b-
isomer 16 and not of the expected a-product, while the xy-
losylation of 14 produced a 1.4:1 mixture of the a- and b-
isomers of 15. The configurations of the glycosyl bonds
formed in these products were deduced from the corre-
sponding J1¢,2¢ coupling constants, which were 3.5 and 7.0
Hz for the a- and b-xylopyranosyl residues, respectively,
in the mixture of 15 and 6.4 Hz for the b-xylopyranosyl
unit in 16. These exceptional stereochemical results from
the xylosylations of spatially hindered bicyclic acceptors
12 and 14 could be connected with their structural organi-
zation, which does not permit coupling from the a-side.
Such cases have been described previously.12,13
CH2Cl2–Et2O TMSOTf
CH2Cl2 BF3·OEt2
2.5:1
1:4
a 5 mol%.
3 than in the benzylidene derivatives 12 and 14. The re-
sults of the xylosylation reactions performed are present-
ed in Table 1. Thus, xylosylation under the conditions
used in the reaction with acceptors 12 and 14 afforded a
mixture of the corresponding a-isomers (J1¢,2¢ = 3.4 Hz)
and b-isomers (J1¢,2¢ = 8.2 Hz) in a ratio of 4.2:1 (entry 2).
An increase in the reaction temperature to 20 °C (entry 1)
reversed the stereoselectivity [(a/b) 1:1.4], while lower-
ing it down to –90 °C (entry 3, reaction time of 15 min)
To overcome this limitation, 1,2:5,6-di-O-isopropylidene-
glucofuranose 17 was studied next as a xylosyl acceptor
with better spatial availability of the hydroxy group at C-
Synthesis 2007, No. 20, 3147–3154 © Thieme Stuttgart · New York

PAPER
Stereoselective Synthesis of 3-Aminopropyl Glycosides
3149
strongly favored the formation of the a-isomer [(a/b) 9:1] yield using hydrazinium acetate in N,N-dimethylforma-
in good yield (86% total yield).
mide.14 Subsequent trichloroacetimidation of the product,
22, afforded disaccharide donor 23, which was coupled
with 3-(trifluoroacetamido)propanol under catalysis using
TMSOTf to give only the b-linked product 24 almost
quantitatively. De-O-benzylation of 24 followed by sa-
ponification of the acyl group produced disaccharide 1 (as
a salt with AcOH) in a yield of 62%. It was further reacted
with an activated ester of octanoic acid15 in the presence
of triethylamine to give the target neoglycolipid 2 in 70%
yield.
Selective acidic de-O-acetylation8 of 24 gave disaccharide
25 in 79% yield (Scheme 4). The glycosylation of 25 with
donor 5 at –40 °C produced a mixture of isomeric trisac-
charides 26a (J1¢¢,2¢¢ = 3.3 Hz) and 26b (J1¢¢,2¢¢ = 7.9 Hz) with
moderate stereoselectivity [(a/b) 2.7:1] and in a total yield
of 70%. This reaction, performed at –90 °C, was more ste-
reoselective [(a/b) 4.4:1] and efficient (Scheme 5), and
the a- and b-isomers were separated by column chroma-
tography to give 26a and 26b in 63% and 15% yields, re-
spectively. The removal of all of the protecting groups in
compound 26a afforded the target trisaccharide 3 (as a salt
with AcOH) in 66% yield. Compound 3 was then trans-
formed into neoglycolipid 4 in 74% yield by N-octanoy-
lation.
The coupling of compounds 5 and 17 in dichloromethane–
diethyl ether (1:3) (entry 4) was less efficient than in
dichloromethane (entry 2) and proceeded with lower ste-
reoselectivity [(a/b) 2.5:1] and yield (61%), probably due
to the solvation effect of diethyl ether. It is noteworthy
that the boron trifluoride–diethyl ether complex promoted
xylosylation (entry 5) gave the b-disaccharide as the ma-
jor product [(a/b) 1:4].
The protocol in entry 3 provided the highest a-stereose-
lectivity and, thus, was used for the preparation of the a-
isomer of 18 (Scheme 4). The a- and b-isomers were sep-
arated by column chromatography after removal of the
5,6-acetonide under mild acid hydrolysis with aqueous
acetic acid to give 19a and 19b.
Acid hydrolysis of 19a with aqueous trifluoroacetic acid
in ethyl acetate resulted in the removal of the 1,2-ace-
tonide followed by the rearrangement of the furanose unit
into the corresponding pyranose to give 20. The presence
of ethyl acetate prevented undesirable de-O-acetylation in
the xylopyranose residue. Benzoylation of the resulting
disaccharide 20 with benzoyl chloride in pyridine afford-
ed the fully protected derivative 21. Selective removal of
the O-benzoyl group at C-1 in 21 was achieved in 72%
Me
O
Me
O
O
O
Me
a
O
O
Me
O
BnO
O
AcO
BnO
HO
O
O
5
+
O
Me
O
Me
Me
18
Me
17
b
HO
HO
OR2
O
R2O
O
O
O
19β
O
R2O
OR1
+
BnO
BnO
O
AcO
BnO
O
AcO
BnO
Me
O
Me
c
20 R1 = H, R2 = H
21 R1 = R2 = Bz
19α
d
e
22 R1 = H, R2 = Bz
OBz
O
g
f
H
N
BzO
23 R1 = C(NH)CCl3,
R2 = Bz
CF3
O
O
OBz
BnO
O
RO
BnO
O
h
j
2
1
24 R = Ac
25 R = H
k
Scheme 4 Reagents and conditions: (a) see Table 1; (b) 80% aq AcOH, 45 °C (71% yield of 19a, 8% yield of 19b); (c) 90% aq TFA, EtOAc,
45 °C, 30 min (91% yield); (d) BzCl, py, 96 h (74% yield); (e) H2NNH2·AcOH, DMF, 4 °C, 18 h (72% yield); (f) CCl3CN, DBU, CH2Cl2 (84%
yield); (g) HO(CH2)3NHCOCF3, TMSOTf, CH2Cl2, –40 °C, 5 min (98% yield); (h) 1. H2, Pd/C, EtOAc; 2. 1.0 M aq NaOH, MeOH (62% yield);
(j) N-(octanoyloxy)succinimide, Et3N, DMF, r.t., 1 h (70% yield); (k) 0.5 M HCl in MeOH (79% yield).
Synthesis 2007, No. 20, 3147–3154 © Thieme Stuttgart · New York

3150
V. Krylov et al.
PAPER
Anal. Calcd for C24H28O6: C, 69.89; H, 6.84. Found: C, 70.04; H,
6.96.
OBz
O
H
N
BzO
OBn
AcO
O
CF3
O
BnO
OBz
BnO
O
O
O
2,4-Di-O-benzyl-3-O-acetyl-D-xylopyranosyl 2,2,2-Trichloro-
acetimidate (5)
BnO
O
26β
To a solution of allyl xylopyranoside 8 (2.15 g, 5.22 mmol) in anhyd
MeOH (44 mL) was added PdCl2 (461 mg, 2.61 mmol). The mix-
ture was stirred for 2 h and then filtered through a Celite pad. The
solution was neutralized with Et3N (0.5 mL) and then concentrated.
The residue was purified by flash chromatography (petroleum
ether–EtOAc, 3:1) to give the hemiacetal as a white foam. A mix-
ture of the resultant hemiacetal (1.51 g, 4.07 mmol), CCl3CN (4 mL,
40.7 mmol), and DBU (100 mL) in anhyd CH2Cl2 (25 mL) was
stirred for 1 h at –30 °C under Ar and then concentrated. The residue
was purified by flash chromatography (silica gel passivated with
Et3N, petroleum ether–EtOAc, 7:1) to give the trichloroacetimidate
5 as a white solid. Yield: 1.81 g (67%); ratio (a/b) ~1:1 (determined
by NMR spectroscopy); Rf = 0.68 (a), 0.56 (b) (toluene–EtOAc–
Et3N, 2:1:0.1).
a
5 + 25
+
OBz
O
O
BnO
AcO
H
N
BzO
O
CF3
O
BnO
BnO
OBz
O
b
O
BnO
O
c
4
3
26α
Scheme 5 Reagents and conditions: (a) TMSOTf, CH2Cl2, –90 °C
(63% yield of 26a, 15% yield of 26b); (b) 1. H2, Pd/C, EtOAc; 2. 1.0
M aq NaOH, MeOH (66% yield); (c) N-(octanoyloxy)succinimide,
Et3N, DMF, r.t., 1 h (74% yield).
a-Isomer
In conclusion, the synthesis of spacer-armed oligosaccha-
rides 1 and 3 and their N-octanoyl derivatives 2 and 4 was
achieved. The 3-O-acetylated xylosyl donor 5 was suc-
cessfully applied to a-xylopyranosyl bond formations, but
it was shown that the structure of the acceptor could influ-
ence the stereoselectivity of these glycosylations. The bi-
ological evaluation of the target oligosaccharides will be
published elsewhere.
1H NMR (250 MHz, CDCl3): d = 2.00 (s, 3 H, CH3), 3.51–3.87 (m,
4 H, H-2, H-4, H-5), 4.50–4.70 (m, 4 H, 2 CH2Ph), 5.53 (t, J2,3
J3,4 = 9.6 Hz, 1 H, H-3), 6.39 (d, J1,2 = 3.6 Hz, 1 H, H-1), 7.20–7.45
(m, 10 H, 2 Ph), 8.59 (s, 1 H, NH).
=
b-Isomer
1H NMR (250 MHz, CDCl3): d = 2.07 (s, 3 H, CH3), 3.51–3.70 (m,
3 H, H-2, H-4, H-5a), 4.03–4.19 (m, 3 H, CH2Ph, H-5b), 4.50–4.70
(m, 2 H, CH2Ph), 5.28 (t, J2,3 = J3,4 = 7.8 Hz, 1 H, H-3), 5.92 (d,
J1,2 = 6.5 Hz, 1 H, H-1), 7.20–7.45 (m, 10 H, 2 Ph), 8.73 (s, 1 H,
NH).
Thin-layer chromatography was performed on silica gel 60 F254
(Merck) with detection by charring with H3PO4. Liquid chromatog-
raphy was performed on silica gel 60–200 mm (Fluka). Gel chroma-
tography was performed on a BioBeads SX-3 (Bio Rad) column (2
× 70 cm) by elution with toluene at a flow rate of 1 mL/min, on a
TSK HW-40(S) column (4 × 70 cm) by elution with 0.1 M aq AcOH
at a flow rate of 0.8 mL/min, and on a Sephadex G-15 column (4 ×
70 cm) by elution with H2O at a flow rate of 1.5 mL/min. Optical
rotations were determined with a Jasco DIP-360 digital polarimeter
at 26–30 °C. All solvents used for the syntheses were purified ac-
cording to conventional procedures.16 1H NMR spectra for substi-
tuted compounds 5–26 were recorded on Bruker spectrometers
WM-250, AM-300, and DRX-500 at 303 K. NMR spectra for oli-
gosaccharides 1–4 were recorded in D2O on a Bruker DRX-500
spectrometer with acetone as a reference (1H NMR: 2.225 ppm).
Gradient enhanced 2D gCOSY, gNOESY, and gHSQC experi-
ments, as well as TOCSY experiments, were used for resonance as-
signment. Mass spectra of the compounds synthesized were
recorded on a Finnigan LCQ mass spectrometer.
Anal. Calcd for C23H24Cl3NO6: C, 53.45; H, 4.68; N, 2.71. Found:
C, 53.57; H, 4.72; N, 2.66.
3-(Trifluoroacetamido)propyl 2,3,4,6-Tetra-O-acetyl-b-D-glu-
copyranoside (10)
To a solution of bromide 9 (4 g, 9.73 mmol) and 3-(trifluoroacet-
amido)propanol (1.47 g, 11.68 mmol) in anhyd CH2Cl2 (40 mL)
were added Hg(CN)2 (2.57 g, 10.22 mmol) and HgBr2 (50 mg, 0.14
mmol). The mixture was stirred at r.t. for 6 h under Ar. Saturated so-
lutions of aq KBr (120 mL) and aq NaHCO3 (30 mL) were added to
the mixture, which was then extracted with CHCl3 (2 × 200 mL).
The extracts were combined, dried (Na2SO4), and concentrated, and
column chromatography of the residue gave glucopyranoside 10 as
a white solid. Yield: 3.02 g (62%); [a]D –15 (c 2, EtOAc); Rf = 0.52
(toluene–acetone, 4:1).
1H NMR (300 MHz, CDCl3): d = 1.70 (m, 2 H, CH2CH2CH2), 2.00
(4 s, 12 H, 4 CH3), 3.38 (2 m, 2 H, CH2CH2NH), 3.66 (m, 2 H, H-5,
OCHH¢CH2), 3.85 (m, 1 H, OCHH¢CH2), 4.16 (m, 2 H, H-6), 4.48
(d, J1,2 = 7.9 Hz, 1 H, H-1), 4.90 (t, J1,2 = J2,3 = 8.1 Hz, 1 H, H-2),
5.01 (t, J3,4 = J4,5 = 9.6 Hz, 1 H, H-4), 5.16 (t, J2,3 = J3,4 = 9.4 Hz, 1
H, H-3), 7.15 (br s, 1 H, NH).
Allyl 2,4-Di-O-benzyl-3-O-acetyl-a-D-xylopyranoside (8)
To a solution of allyl xylopyranoside 74 (2.00 g, 5.41 mmol) in py
(8 mL) was added Ac2O (1.5 mL). The mixture was kept for 5 h at
r.t., after which MeOH (5 mL) was added dropwise while cooling.
The mixture was stored for 20 min at r.t. and then diluted with tol-
uene (20 mL) and concentrated in vacuo. Column chromatography
of the residue gave xylopyranoside 8 as a colorless oil. Yield: 2.21
g (99%); [a]D 81 (c 1, EtOAc); Rf = 0.32 (toluene–EtOAc, 20:1).
Anal. Calcd for C19H26F3NO11: C, 45.51; H, 5.23; N, 2.79. Found:
C, 45.73; H, 4.99; N, 3.03.
3-(Trifluoroacetamido)propyl 4,6-O-Benzylidene-b-D-glucopy-
ranoside (11)
To a stirred solution of 10 (2.5 g, 4.99 mmol) in anhyd MeOH (40
mL) was added 30% NaOMe in MeOH (0.2 mL, 0.55 mmol). The
mixture was stirred for 4 h at r.t. and then was neutralized with Am-
berlite IR-120 (H+). The resin was filtered off and the filtrate was
concentrated. The residue was suspended in anhyd MeCN (40 mL)
and then benzaldehyde dimethyl acetal (1.0 mL, 6.61 mmol) and
( )-CSA (0.1 g, 0.44 mmol) were added. The mixture was stirred for
3 h at 45 °C and then was neutralized with Et3N, and the solvent was
1H NMR (250 MHz, CDCl3): d = 2.02 (s, 3 H, CH3), 3.42 (dd, J1,2
=
3.5 Hz, J2,3 = 9.9 Hz, 1 H, H-2), 3.53 (q, J3,4 = J4,5a = J4,5b = 8.4 Hz,
1 H, H-4), 3.65 (m, 2 H, H-5), 3.97–4.20 (m, 2 H, CH2=CHCH2O),
4.58 (q, J = 12.1 Hz, 4 H, 2 CH2Ph), 4.80 (d, J1,2 = 3.5 Hz, 1 H, H-
1), 5.20–5.37 (m, 2 H, CH2=CHCH2O), 5.50 (t, J2,3 = J3,4 = 10.0 Hz,
1 H, H-3), 5.95 (m, 1 H, CH2=CHCH2O), 7.15–7.40 (m, 10 H, 2 Ph).
Synthesis 2007, No. 20, 3147–3154 © Thieme Stuttgart · New York

PAPER
Stereoselective Synthesis of 3-Aminopropyl Glycosides
3151
evaporated in vacuo. The residue was purified by column chroma-
tography (silica gel, toluene–EtOAc, 2:1) to give diol 11 as a white
solid. Yield: 1.49 g (71%); [a]D –31 (c 2, EtOAc); Rf = 0.57
(EtOAc).
J6a,6b = 10.3 Hz, 1 H, H-6a), 4.04 (m, 1 H, OCHH¢CH2), 4.33 (dd,
J5,6b = 4.9 Hz, J6a,6b = 10.5 Hz, 1 H, H-6b), 4.41 (d, J1,2 = 7.8 Hz, 1
H, H-1), 4.73, 4.98 (2 d, J = 11.8 Hz, 2 H, PhCH2), 5.55 (s, 1 H,
PhCH), 7.25–7.48 (m, 11 H, 2 Ph, NH).
1H NMR (250 MHz, CDCl3): d = 1.86 (m, 2 H, CH2CH2CH2), 3.36–
3.81 (m, 8 H, H-2, H-3, H-4, H-5, H-6a, CH2CH2NH, OCHH¢CH2),
4.00 (m, 1 H, OCHH¢CH2), 4.29 (dd, J5,6b = 4.8 Hz, J6a,6b = 10.6 Hz,
1 H, H-6b), 4.40 (d, J1,2 = 7.7 Hz, 1 H, H-1), 5.50 (s, 1 H, PhCH),
7.25–7.40 (m, 5 H, Ph).
To confirm the structures of 13 and 14, small portions (~4–5 mg) of
the compounds were acetylated as described for preparation 8.
Acetylated derivative of 13
1H NMR (250 MHz, CDCl3): d = 1.85 (m, 2 H, CH2CH2CH2), 1.99
(s, 3 H, CH3), 3.30–3.62 (m, 5 H, H-3, H-4, H-5, CH2CH2NH),
3.72–3.81 (m, 2 H, H-6a, OCHH¢CH2), 3.95 (m, 1 H, OCHH¢CH2),
Anal. Calcd for C18H22F3NO7: C, 51.31; H, 5.26; N, 3.32. Found: C,
51.39; H, 5.51; N, 3.13.
4.33 (dd, J5,6b = 4.7 Hz, J6a,6b = 10.2 Hz, 1 H, H-6b), 4.40 (d, J1,2
7.9 Hz, 1 H, H-1), 4.73 (q, J = 12.1 Hz, 2 H, PhCH2), 4.93 (t, J1,2
=
=
3-(Trifluoroacetamido)propyl 2-O-Benzoyl-4,6-O-benzylidene-
b-D-glucopyranoside (12)
J2,3 = 8.2 Hz, 1 H, H-2), 5.48 (s, 1 H, PhCH), 6.95 (br s, 1 H, NH),
7.08–7.53 (m, 10 H, 2 Ph).
A mixture of diol 11 (500 mg, 1.19 mmol) and Bu2SnO (311 mg,
1.25 mmol) in anhyd toluene (15 mL) was refluxed with azeotropic
removal of H2O to a volume of 4 mL. The mixture was then treated
with BzCl (0.15 mL, 1.31 mmol), kept for 1 h at r.t., and then con-
centrated. Column chromatography (silica gel, toluene–EtOAc,
5:1) of the residue afforded the 2-O-benzoyl derivative 12 as a white
solid. Yield: 463 mg (74%); [a]D –32 (c 2, EtOAc); Rf = 0.37 (tolu-
ene–EtOAc, 3:1).
1H NMR (250 MHz, CDCl3): d = 1.73 (m, 2 H, CH2CH2CH2), 2.67
(br s, 1 H, OH), 3.19–3.76 (m, 5 H, H-4, H-5, CH2CH2NH,
OCHH¢CH2), 3.84 (t, J6a,6b = J5,6a = 10.2 Hz, 1 H, H-6a), 3.96 (m, 1
H, OCHH¢CH2), 4.10 (t, J2,3 = J3,4 = 9.1 Hz, 1 H, H-3), 4.41 (dd,
J5,6b = 4.9 Hz, J6a,6b = 10.5 Hz, 1 H, H-6b), 4.70 (d, J1,2 = 7.9 Hz, 1
H, H-1), 5.21 (t, J1,2 = J2,3 = 8.3 Hz, 1 H, H-2), 5.59 (s, 1 H, PhCH),
6.95 (br s, 1 H, NH), 7.12–8.15 (m, 10 H, 2 Ph).
Acetylated derivative of 14
1H NMR (250 MHz, CDCl3): d = 1.88 (m, 2 H, CH2CH2CH2), 1.96
(s, 3 H, CH3), 3.38 (t, J1,2 = 7.8 Hz, J2,3 = 9.1 Hz, 1 H, H-2), 3.42–
3.57 (m, 4 H, H-4, H-5, CH2CH2NH), 3.72 (t, J5,6a = J6a,6b = 10.3 Hz,
1 H, H-6a), 3.79 (m, 1 H, OCHH¢CH2), 3.93 (m, 1 H, OCHH¢CH2),
4.32 (dd, J5,6b = 4.8 Hz, J6a,6b = 10.4 Hz, 1 H, H-6b), 4.56 (d, J1,2
=
7.7 Hz, 1 H, H-1), 4.63, 4.78 (2 d, J = 11.4 Hz, 2 H, PhCH2), 5.31
(t, J2,3 = J3,4 = 9.4 Hz, 1 H, H-3), 5.46 (s, 1 H, PhCH), 6.90 (br s, 1
H, NH), 7.05–7.48 (m, 10 H, 2 Ph).
Glycosylation; General Procedure
To a solution of the glycosyl donor (1.1 mmol) and glycosyl accep-
tor (1.0 mmol) in anhyd CH2Cl2 (5 mL) under Ar was added 1 M
TMSOTf in CH2Cl2 (50 mL) at –40 °C, and the mixture was stirred.
The mixture was neutralized with Et3N and evaporated. Column
chromatography of the residue (silica gel, toluene–EtOAc, 15:1 to
7:1), followed by chromatography on a BioBeads SX-3 gel column
gave the glycosylation product.
Anal. Calcd for C25H26F3NO8: C, 57.14; H, 4.99; N, 2.67. Found: C,
56.85; H, 5.21; N, 2.47.
3-(Trifluoroacetamido)propyl 3-O-Benzyl-4,6-O-benzylidene-
b-D-glucopyranoside (13) and 3-(Trifluoroacetamido)propyl 2-
O-Benzyl-4,6-O-benzylidene-b-D-glucopyranoside (14)
A mixture of diol 11 (300 mg, 0.71 mmol) and Bu2SnO (197 mg,
0.79 mmol) in anhyd toluene (10 mL) was refluxed with azeotropic
removal of H2O to a volume of 2 mL. Then, BnBr (94 mL, 0.79
mmol) and TBAB (254 mg, 0.79 mmol) were added, and the mix-
ture was kept for 5 h at 60 °C and then concentrated. Column chro-
matography (silica gel, toluene–EtOAc, 5:1) of the residue afforded
the 2-O-benzyl derivative 14 as a white solid, as well as the 3-O-
benzyl derivative 13.
3-(Trifluoroacetamido)propyl 3-O-Acetyl-2,4-di-O-benzyl-D-
xylopyranosyl-(1→3)-2-O-benzyl-4,6-O-benzylidene-b-D-glu-
copyranoside (15)
Glycosylation of monosaccharide 14 (60 mg, 0.117 mmol) with
trichloroacetimidate 5 (63 mg, 0.126 mmol) as described in the gen-
eral procedure was complete within 50 min and gave disaccharide
15. Yield: 66 mg (65%); Rf = 0.42 (toluene–EtOAc, 3:1).
a-Isomer
1H NMR (250 MHz, CDCl3): d = 1.86 (m, 2 H, CH2CH2CH2), 2.00
(s, 3 H, CH3), 3.23 (dd, J1¢,2¢ = 3.5 Hz, J2¢,3¢ = 10.0 Hz, 1 H, H-2¢),
3.36–3.52 (m, 7 H, H-2, H-5, H-4¢, H-5¢, CH2CH2NH), 3.72 (t,
J5,6a = J6a,6b = 10.3 Hz, 1 H, H-6a), 3.75–3.94 (m, 3 H, H-4,
OCH2CH2), 4.03 (t, J2,3 = J3,4 = 9.2 Hz, 1 H, H-3), 4.17 (d, J = 12.8
Hz, 1 H, PhCHH¢), 4.33 (dd, J5,6b = 5.0 Hz, J6a,6b = 10.5 Hz, 1 H, H-
6b), 4.38–4.55 (m, 4 H, H-1, PhCH2, PhCHH¢), 4.82 (s, 2 H,
PhCH2), 5.38 (s, 1 H, PhCH), 5.46 (m, 2 H, H-1¢, H-3¢), 6.85–7.39
(m, 20 H, 4 Ph).
14
Yield: 76 mg (21%); [a]D –20 (c 1, CHCl3); Rf = 0.26 (toluene–
EtOAc, 3:1).
1H NMR (500 MHz, CDCl3): d = 1.86 (m, 2 H, CH2CH2CH2), 2.55
(br s, 1 H, OH), 3.31 (t, J1,2 = J2,3 = 8.5 Hz, 1 H, H-2), 3.37–3.55 (m,
4 H, H-4, H-5, CH2CH2NH), 3.70–3.78 (m, 2 H, H-6a, OCHH¢CH2),
3.85 (dt, J2,3 = J3,4 = 8.7 Hz, J3,OH = 2.2 Hz, 1 H, H-3), 3.91 (m, 1 H,
OCHH¢CH2), 4.31 (dd, J5,6 = 4.9 Hz, J6a,6b = 10.4 Hz, 1 H, H-6b),
4.49 (d, J1,2 = 7.7 Hz, 1 H, H-1), 4.79, 4.83 (2 d, J = 11.6 Hz, 2 H,
PhCH2), 5.52 (s, 1 H, PhCH), 6.93 (br s, 1 H, NH), 7.25–7.48 (m,
10 H, 2 Ph).
b-Isomer
1H NMR (250 MHz, CDCl3): d = 1.85 (m, 2 H, CH2CH2CH2), 1.95
(s, 3 H, CH3), 3.11 (t, J5a¢,5b¢ = J4¢,5a¢ = 9.6 Hz, 1 H, H-5a¢), 3.35 (t,
J
1¢,2¢ = J2¢,3¢ = 8.8 Hz, 1 H, H-2¢), 3.40–3.56 (m, 5 H, H-2, H-5, H-4¢,
CH2CH2NH), 3.63 (t, J3,4 = J4,5 = 9.3 Hz, 1 H, H-4), 3.77 (m, 2 H,
H-6a, OCHH¢CH2), 3.90 (m, 2 H, H-5b¢, OCHH¢CH2), 4.06 (t, J2,3
Anal. Calcd for C25H28F3NO7: C, 58.71; H, 5.52; N, 2.74. Found: C,
58.59; H, 5.78; N, 2.55.
=
J3,4 = 9.0 Hz, 1 H, H-3), 4.13 (q, J = 12.3 Hz, 2 H, PhCH2), 4.35 (dd,
J5,6b = 4.8 Hz, J6a,6b = 10.3 Hz, 1 H, H-6b), 4.50 (d, J1,2 = 5.3 Hz, 1
H, H-1), 4.57–4.88 (m, 4 H, 2 PhCH2), 4.92 (d, J1¢,2¢ = 7.0 Hz, 1 H,
H-1¢), 5.14 (t, J2¢,3¢ = J3¢,4¢ = 8.9 Hz, 1 H, H-3¢), 5.55 (s, 1 H, PhCH),
6.92 (br s, 1 H, NH), 7.12–7.55 (m, 20 H, 4 Ph).
13
Yield: 162 mg (45%); Rf = 0.37 (toluene–EtOAc, 3:1).
1H NMR (500 MHz, CDCl3): d = 1.87 (m, 2 H, CH2CH2CH2), 2.55
(br s, 1 H, OH), 3.38–3.58 (m, 3 H, H-2, H-5, CH2CHH¢NH), 3.59–
3.74 (m, 4 H, H-3, H-4, CH2CHH¢NH, OCHH¢CH2), 3.77 (t, J5,6a
=
Synthesis 2007, No. 20, 3147–3154 © Thieme Stuttgart · New York

3152
V. Krylov et al.
PAPER
3-(Trifluoroacetamido)propyl 3-O-Acetyl-2,4-di-O-benzyl-b-D-
xylopyranosyl-(1→3)-2-O-benzoyl-4,6-O-benzylidene-b-D-glu-
copyranoside (16)
Glycosylation of monosaccharide 12 (60 mg, 0.114 mmol) with
trichloroacetimidate 5 (63 mg, 0.126 mmol) as described in the gen-
eral procedure was complete within 50 min and gave disaccharide
16. Yield: 72 mg (72%); Rf = 0.47 (toluene–EtOAc, 3:1).
1H NMR (250 MHz, CDCl3): d = 1.70 (m, 5 H, CH3, CH2CH2CH2),
3.12 (dd, J4¢,5a¢ = 8.6 Hz, J5a¢,5b¢ = 11.8 Hz, 1 H, H-5a¢), 3.22 (m, 2 H,
H-2¢, CH2CHH¢NH), 3.40–4.00 (m, 8 H, H-4, H-5, H-6a, H-4¢, H-
5b¢, CH2CHH¢NH, OCH2CH2), 4.23–4.33 (m, 6 H, H-3, H-6b, 2
PhCH2), 4.65 (d, J1,2 = 7.9 Hz, 1 H, H-1), 4.71 (d, J1¢,2¢ = 6.4 Hz, 1
H-2, H-3, H-4, H-5, H-6, H-1¢), 5.15 (t, J2¢,3¢ = J3¢,4¢ = 9.6 Hz, 1 H,
H-3¢), 5.81 (d, J1,2 = 3.7 Hz, 1 H, H-1), 7.17–7.42 (m, 10 H, 2 Ph).
3-O-Acetyl-2,4-di-O-benzyl-a-D-xylopyranosyl-(1→3)-D-glu-
copyranose (20)
To a solution of disaccharide 19a (225 mg, 0.39 mmol) in EtOAc (7
mL) was added 90% aq TFA (7 mL). The mixture was kept for 30
min at 45 °C and then was concentrated. Column chromatography
of the residue (CHCl3–MeOH, 15:1 to 10:1) gave product 20 as a
colorless oil. Yield: 191 mg (91%); ratio (a/b) ~1:1 (determined by
NMR spectroscopy); Rf = 0.20 (CHCl3–MeOH, 10:1).
a-Isomer
H, H-1¢), 4.97 (t, J2¢,3¢ = J3¢,4¢ = 8.5 Hz, 1 H, H-3¢), 5.37 (t, J1,2
=
1H NMR (250 MHz, CD3OD): d = 1.95 (s, 3 H, CH3), 3.43–4.12 (m,
10 H, H-2, H-3, H-4, H-5, H-6, H-2¢, H-4¢, H-5¢), 4.50–4.81 (m, 4
J2,3 = 8.4 Hz, 1 H, H-2), 5.58 (s, 1 H, PhCH), 6.92–7.95 (m, 20 H, 4
Ph).
H, 2 CH2Ph), 5.11 (d, J1,2 = 3.7 Hz, 1 H, H-1), 5.36 (t, J2,3 = J3,4
=
9.6 Hz, 1 H, H-3¢), 5.53 (d, J1¢,2¢ = 2.0 Hz, 1 H, H-1¢), 7.25–7.40 (m,
10 H, 2 Ph).
3-O-Acetyl-2,4-di-O-benzyl-D-xylopyranosyl-(1→3)-1,2:5,6-di-
O-isopropylidene-a-D-glucofuranose (18)
Glycosylation of monosaccharide 17 (619 mg, 2.38 mmol) with
trichloroacetimidate 5 (1.35 g, 2.62 mmol) as described in the gen-
eral procedure, but at –90 °C, gave the product 18 within 15 min as
a white foam. Yield: 1.26 g (86%); ratio (a/b) isomers ~9:1 (deter-
mined by NMR spectroscopy); Rf = 0.67 (toluene–EtOAc, 3:1).
b-Isomer
1H NMR (250 MHz, CD3OD): d = 1.95 (s, 3 H, CH3), 3.25–4.12 (m,
10 H, H-2, H-3, H-4, H-5, H-6, H-2¢, H-4¢, H-5¢), 4.50–4.81 (m, 5
H, 2 CH2Ph, H-1), 5.34 (t, J2¢,3¢ = J3¢,4¢ = 9.6 Hz, 1 H, H-3¢), 5.53 (d,
J1¢,2¢ = 2.0 Hz, 1 H, H-1¢), 7.25–7.40 (m, 10 H, 2 Ph).
a-Isomer
Anal. Calcd for C27H34O11: C, 60.67; H, 6.41. Found: C, 60.42; H,
6.72.
1H NMR (300 MHz, CDCl3): d = 1.21, 1.33, 1.41, 1.50, 2.05 (5 s,
15 H, 5 CH3), 3.41 (dd, J1¢,2¢ = 3.4 Hz, J2¢,3¢ = 10.0 Hz, 1 H, H-2¢),
3.54 (m, 1 H, H-4¢), 3.57–3.80 (m, 2 H, H-5¢), 3.95–4.50 (m, 5 H,
H-3, H-4, H-5, H-6), 4.50–4.75 (m, 5 H, H-2, 2 CH2Ph), 5.21 (d,
Benzoyl 3-O-Acetyl-2,4-di-O-benzyl-a-D-xylopyranosyl-(1→3)-
2,4,6-tri-O-benzoyl-D-glucopyranoside (21)
J
1¢,2¢ = 3.4 Hz, 1 H, H-1¢), 5.39 (t, J2¢,3¢ = J3¢,4¢ = 9.5 Hz, 1 H, H-3¢),
A solution of disaccharide 20 (200 mg, 0.37 mmol) and BzCl (1 mL,
10.90 mmol) in py (5 mL) was stirred for 96 h at r.t. Then, H2O (40
mL) was added and the suspension formed was extracted with
CH2Cl2 (3 × 20 mL). The extracts were combined, dried (MgSO4),
and concentrated. Column chromatography of the residue (silica
gel, toluene–EtOAc, 20:1) gave product 21 as a white solid. Yield:
260 mg (74%); ratio (a/b) ~1:1 (determined by NMR spectrosco-
py); Rf = 0.59 (toluene–EtOAc, 7:1).
5.93 (d, J1,2 = 3.5 Hz, 1 H, H-1), 7.20–7.40 (m, 10 H, 2 Ph).
b-Isomer
1H NMR (300 MHz, CDCl3): d = 1.25, 1.35, 1.45, 1.50, 1.95 (5 s,
15 H, 5 CH3), 3.23 (t, J1¢,2¢ = J2¢,3¢ = 8.2 Hz, 1 H, H-2¢), 3.29 (m, 1 H,
H-5a¢), 3.52 (m, 1 H, H-4¢), 4.00 (dd, J4¢,5b¢ = 5.3 Hz, J5a¢,5b¢ = 12.1
Hz, 1 H, H-5b¢), 4.03–4.60 (m, 9 H, CH2Ph, H-2, H-3, H-4, H-5, H-
6, H-1¢), 4.67 (q, J = 11.4 Hz, 2 H, CH2Ph), 5.14 (t, J2¢,3¢ = J3¢,4¢ = 9.2
Hz, 1 H, H-3¢), 5.77 (d, J1,2 = 3.8 Hz, 1 H, H-1), 7.20–7.40 (m, 10
H, 2 Ph).
a-Isomer
1H NMR (250 MHz, CDCl3): d = 1.85 (s, 3 H, CH3), 3.09–3.43 (m,
4 H, H-2¢, H-4¢, H-5¢), 3.58–4.70 (m, 8 H, 2 CH2Ph, 3-H, 5-H, 6-H),
4.92 (d, J1¢,2¢ = 3.2 Hz, 1 H, H-1¢), 5.26 (t, J2¢,3¢ = J3¢,4¢ = 9.5 Hz, 1 H,
Anal. Calcd for C33H42O11: C, 64.48; H, 6.89. Found: C, 64.21; H,
6.74.
H-3¢), 5.59 (dd, J1,2 = 3.7 Hz, J2,3 = 9.8 Hz, 1 H, H-2), 5.80 (t, J3,4
=
J4,5 = 9.8 Hz, 1 H, H-4), 6.76 (d, J1,2 = 3.6 Hz, 1 H, H-1), 6.90–8.15
3-O-Acetyl-2,4-di-O-benzyl-a-D-xylopyranosyl-(1→3)-1,2-O-
isopropylidene-a-D-glucofuranose (19a)
(m, 30 H, 6 Ph).
A solution of disaccharide product 18 (1.21 g, 1.97 mmol) in 80%
aq AcOH (40 mL) was kept for 4 h at 45 °C, and then the mixture
was concentrated. Column chromatography of the residue (petro-
leum ether–EtOAc, 2:3) gave the individual disaccharide 19a.
Yield: 803 mg (71%); [a]D 68 (c 1, EtOAc); Rf = 0.32 (petroleum
ether–EtOAc, 2:3).
1H NMR (300 MHz, CDCl3): d = 1.27, 1.49, 2.04 (3 s, 9 H, 3 CH3),
3.46 (dd, J1¢,2¢ = 3.5 Hz, J2¢,3¢ = 10.0 Hz, 1 H, H-2¢), 3.50–4.25 (m, 8
H, H-3, H-4, H-5, H-6, H-4¢, H-5a¢, H-5b¢), 4.49–4.74 (m, 5 H, H-
b-Isomer
1H NMR (250 MHz, CDCl3): d = 1.87 (s, 3 H, CH3), 3.09–3.43 (m,
4 H, H-2¢, H-4¢, H-5¢), 3.58–4.70 (m, 8 H, 2 CH2Ph, 3-H, 5-H, 6-H),
4.96 (d, J1¢,2¢ = 3.3 Hz, 1 H, H-1¢), 5.35 (t, J2¢,3¢ = J3¢,4¢ = 9.7 Hz, 1 H,
H-3¢), 5.64–5.77 (m, 2 H, H-2, H-4), 6.23 (d, J1,2 = 6.9 Hz, 1 H, H-
1), 6.90–8.15 (m, 30 H, 6 Ph).
Anal. Calcd for C55H50O15: C, 69.46; H, 5.30. Found: C, 69.61; H,
5.38.
1¢, 2 CH2Ph), 4.78 (d, J1,2 = 3.5 Hz, 1 H, H-2), 5.41 (t, J2¢,3¢ = J3¢,4¢
=
3-O-Acetyl-2,4-di-O-benzyl-a-D-xylopyranosyl-(1→3)-2,4,6-tri-
O-benzoyl-D-glucopyranose (22)
9.6 Hz, 1 H, H-3¢), 5.92 (d, J1,2 = 3.5 Hz, 1 H, H-1), 7.25–7.40 (m,
10 H, 2 Ph).
To a solution of disaccharide 21 (240 mg, 0.25 mmol) in anhyd
DMF (10 mL) was added H2NNH2·AcOH (440 mg, 4.8 mmol). The
mixture was stirred for 18 h at 4 °C, then brine (50 mL) was added
and the mixture was extracted with EtOAc (3 × 60 mL). The ex-
tracts were combined, dried (MgSO4), concentrated. Column chro-
matography of the residue (silica gel, toluene–EtOAc, 8:1) gave
disaccharide 22 as a white solid. Yield: 152 mg (72%); ratio (a/b)
~10:1 (NMR); Rf = 0.33 (toluene–EtOAc, 5:1).
Anal. Calcd for C30H38O11: C, 62.71; H, 6.67. Found: C, 62.39; H,
6.81.
In addition, isomeric 19b was isolated from the mixture. Yield: 95
mg (8%); Rf = 0.26 (petroleum ether–EtOAc, 2:3).
1H NMR (300 MHz, CDCl3): d = 1.26, 1.40, 2.00 (3 s, 9 H, 3 CH3),
3.29 (t, J1¢,2¢ = J2¢,3¢ = 7.4 Hz, 1 H, H-2¢), 3.35 (m, 1 H, H-5a¢), 3.50
(m, 1 H, H-4¢), 4.06 (m, 1 H, H-5b¢), 4.12–4.68 (m, 11 H, 2 CH2Ph,
Synthesis 2007, No. 20, 3147–3154 © Thieme Stuttgart · New York

PAPER
Stereoselective Synthesis of 3-Aminopropyl Glycosides
3153
a-Isomer
uo. The residue was purified by flash chromatography (toluene–
EtOAc, 1:1) to give the diol as a white solid. This compound was
dissolved in MeOH (0.8 mL), 1.0 M aq NaOH (0.8 mL) was added,
and the mixture was kept for 24 h at r.t. Then, the mixture was neu-
tralized with 10% aq AcOH and concentrated. The deprotected dis-
accharide 1 was isolated as a salt with AcOH by chromatography on
a TSK HW-40(S) gel column. Yield: 32 mg (0.075 mmol, 62%);
[a]D 63 (c 1, H2O).
1H NMR (500 MHz, CDCl3): d = 1.60 (s, 3 H, CH3), 3.13 (dd,
J
1¢,2¢ = 3.6 Hz, J2¢,3¢ = 10.0 Hz, 1 H, H-2¢), 3.18–3.73 (m, 3 H, H-4¢,
H-5¢), 3.79–4.68 (m, 8 H, H-3, H-5, H-6, 2 CH2Ph), 5.02 (d, J1¢,2¢
=
3.5 Hz, 1 H, H-1¢), 5.26 (m, 2 H, H-2, H-3¢), 5.64 (d, J1,2 = 3.4 Hz,
1 H, H-1), 5.70 (t, J3,4 = J4,5 = 9.6 Hz, 1 H, H-4), 6.85–8.15 (m, 25
H, 5 Ph).
b-Isomer
1H NMR (500 MHz, D2O): d = 1.88 (s, 3 H, CH3), 1.99 (m, 2 H,
Selected 1H NMR (500 MHz, CDCl3): d = 4.88 (d, J1,2 = 7.4 Hz, 1
H, H-1), 5.37 (t, J2¢,3¢ = J3¢,4¢ = 8.2 Hz, 1 H, H-3¢).
CH2CH2CH2), 3.14 (t, J = 7.0 Hz, 2 H, CH2CH2NH), 3.36 (t, J1,2
=
J2,3 = 8.2 Hz, 1 H, H-2), 3.45 (m, 1 H, H-5), 3.52 (dd, J1¢,2¢ = 3.8 Hz,
Anal. Calcd for C48H46O14: C, 68.08; H, 5.47. Found: C, 68.31; H,
5.65.
J
2¢,3¢ = 9.5 Hz, 1 H, H-2¢), 3.56–3.72 (6 H, m, H-3, H-4, H-6a, H-3¢,
H-4¢, H-5a¢), 3.77–3.91 (m, 3 H, H-6b, H-5b¢, OCHH¢CH2), 4.03 (m,
1 H, OCHH¢CH2), 4.47 (d, J1,2 = 8.1 Hz, 1 H, H-1), 5.29 (d, J1¢,2¢
3.7 Hz, 1 H, H-1¢).
=
3-O-Acetyl-2,4-di-O-benzyl-a-D-xylopyranosyl-(1→3)-2,4,6-tri-
O-benzoyl-D-glucopyranosyl Trichloroacetimidate (23)
13C NMR (125 MHz, D2O): d = 24.46 (CH2CH2CH2), 38.75
(CH2CH2NH), 61.69 (C-6), 62.67 (C-5¢), 69.00 (OCH2CH2), 70.50
(C-4¢), 71.30 (C-4), 72.75, 72.87 (C-2, C-2¢), 74.17 (C-3¢), 76.84
(C-5), 82.97 (C-3), 100.25 (C-1¢), 103.52 (C-1).
MS (MALDI): m/z [M]+ calcd for C14H28NO10: 370.171; found:
370.171.
A mixture of hemiacetal 22 (250 mg, 0.30 mmol), CCl3CN (0.3 mL,
3 mmol), and DBU (20 mL) in anhyd CH2Cl2 (4 mL) was stirred for
1 h at –30 °C under Ar and then was concentrated. The residue was
purified by flash chromatography (silica gel passivated with Et3N,
petroleum ether–EtOAc, 5:1) to give the trichloroacetimidate 23 as
a white foam. Yield: 250 mg (84%); ratio (a/b) ~25:1 (determined
by NMR spectroscopy); Rf = 0.50 (toluene–EtOAc–Et3N, 5:1:0.1).
3-(Trifluoroacetamido)propyl 2,4-Di-O-benzyl-a-D-xylopyra-
nosyl-(1→3)-2,4,6-tri-O-benzoyl-b-D-glucopyranoside (25)
To a solution of compound 24 (190 mg, 0.19 mmol) in anhyd
CH2Cl2 (1 mL) was added a solution of HCl in MeOH (0.5 M), pre-
pared by treating anhyd MeOH (5 mL) with AcCl (0.2 mL). The
mixture was kept for 8 h at r.t., then H2O (40 mL) was added and the
mixture was extracted with CH2Cl2 (3 × 40 mL). The extracts were
combined, dried (MgSO4), and concentrated. The residue was puri-
fied by column chromatography (silica gel, toluene–EtOAc, 7:1) to
give disaccharide 25 as a white solid. Yield: 144 mg (79%); [a]D 24
(c 1, EtOAc); Rf = 0.34 (toluene–EtOAc, 5:1).
a-Isomer
1H NMR (500 MHz, CDCl3): d = 1.77 (s, 3 H, CH3), 3.10 (dd,
J1¢,2¢ = 3.6 Hz, J2¢,3¢ = 10.0 Hz, 1 H, H-2¢), 3.18–3.30 (m, 2 H, H-4¢,
H-5a¢), 3.62 (t, J4¢,5b¢ = J5a¢,5b¢ = 10.9 Hz, 1 H, H-5b¢), 3.77–4.27 (m, 4
H, 2 CH2Ph), 4.37 (dd, J5,6a = 5.3 Hz, J6a,6b = 12.3 Hz, 1 H, H-6a),
4.47–4.63 (m, 3 H, H-3, H-5, H-6b), 4.90 (d, J1¢,2¢ = 3.6 Hz, 1 H, H-
1¢), 5.22 (t, J2¢,3¢ = J3¢,4¢ = 9.6 Hz, 1 H, H-3¢), 5.51 (dd, J1,2 = 3.9 Hz,
J2,3 = 9.6 Hz, 1 H, H-2), 5.74 (t, J3,4 = J4,5 = 9.9 Hz, 1 H, H-4), 6.70
(d, J1,2 = 3.9 Hz, 1 H, H-1), 6.87–8.05 (m, 25 H, 5 Ph), 8.57 (s, 1 H,
NH).
1H NMR (300 MHz, CDCl3): d = 1.77 (m, 2 H, CH2CH2CH2), 3.02
(dd, J1¢,2¢ = 3.4 Hz, J2¢,3¢ = 9.5 Hz, 1 H, H-2¢), 3.13–3.29 (m, 3 H, H-
4¢, H-5a¢, CH2CHH¢NH), 3.38–3.57 (m, 2 H, H-5b¢, CH2CHH¢NH),
3.62 (m, 1 H, OCHH¢CH2), 3.85 (t, J2¢,3¢ = J3¢,4¢ = 9.3 Hz, 1 H, H-3¢),
3.89–4.08 (m, 3 H, H-5, PhCHH¢O, OCHH¢CH2), 4.22–4.46 (m, 5
H, H-3, H-6a, PhCHH¢O, PhCH2), 4.69 (m, 2 H, H-1, H-6b), 4.84 (d,
b-Isomer
Selected 1H NMR (500 MHz, CDCl3): d = 6.18 (d, J1,2 = 6.0 Hz, 1
H, 1-H), 8.63 (s, 1 H, NH).
Anal. Calcd for C50H46Cl3NO14: C, 60.58; H, 4.68; N, 1.41. Found:
C, 60.72; H, 4.94; N, 1.39.
J
1¢,2¢ = 3.4 Hz, 1 H, H-1¢), 5.32 (t, J1,2 = J2,3 = 8.2 Hz, 1 H, H-2), 5.62
(t, J3,4 = J4,5 = 9.2 Hz, 1 H, H-4), 6.95–8.05 (m, 25 H, 5 Ph).
3-(Trifluoroacetamido)propyl 3-O-Acetyl-2,4-di-O-benzyl-a-D-
xylopyranosyl-(1→3)-2,4,6-tri-O-benzoyl-b-D-glucopyranoside
(24)
Anal. Calcd for C51H50F3NO14: C, 63.94; H, 5.26; N, 1.46. Found:
C, 63.72; H, 5.45; N, 1.50.
Glycosylation of 3-(trifluoroacetamido)propanol (82 mg, 0.48
mmol) with trichloroacetimidate 23 (236 mg, 0.24 mmol; twofold
excess) as described in the general procedure was complete within
5 min and gave disaccharide 24 as a white solid. Yield: 235 mg
(98%); [a]D 29 (c 1, EtOAc); Rf = 0.39 (toluene–EtOAc, 5:1).
3-(Trifluoroacetamido)propyl 3-O-Acetyl-2,4-di-O-benzyl-a-D-
xylopyranosyl-(1→3)-2,4-O-di-benzyl-a-D-xylopyranosyl-
(1→3)-2,4,6-tri-O-benzoyl-b-D-glucopyranoside (26a)
Glycosylation of disaccharide 25 (140 mg, 0.15 mmol) with trichlo-
roacetimidate 5 (93 mg, 0.18 mmol) as described in the general pro-
cedure, but at –90 °C, gave trisaccharide 26a as a white foam.
Yield: 126 mg (63%); [a]D 24 (c 1, EtOAc); Rf = 0.34 (toluene–
EtOAc, 5:1).
1H NMR (250 MHz, CDCl3): d = 1.73 (m, 2 H, CH2CH2CH2), 1.94
(s, 3 H, CH3), 3.18–3.27 (m, 3 H, H-2¢, H-2¢¢, CH2CHH¢NH), 3.32–
3.64 (m, 7 H, H-4¢, H-4¢¢, H-5¢, H-5a¢¢, CH2CHH¢NH, OCHH¢CH2),
3.82 (t, J4¢¢,5b¢¢ = J5a¢¢,5b¢¢ = 11.1 Hz, 1 H, H-5b¢¢), 3.94 (m, 1 H,
OCHH¢CH2), 4.05–4.49 (m, 12 H, 4 PhCH2, H-3, H-5, H-3¢, H-6a),
4.72 (m, 3 H, 1-H, 1-H¢, H-6b), 5.30 (t, J1,2 = J2,3 = 7.5 Hz, 1 H, H-
2), 5.39 (t, J2¢¢,3¢¢ = J3¢¢,4¢¢ = 9.6 Hz, 1 H, H-3¢¢), 5.56 (d, J1¢¢,2¢¢ = 3.3
Hz, 1 H, H-1¢¢), 5.61 (t, J3,4 = J4,5 = 8.4 Hz, 1 H, H-4), 6.95–8.10 (m,
35 H, 7 Ph).
1H NMR (250 MHz, CDCl3): d = 1.85 (m, 5 H, CH3, CH2CH2CH2),
3.18 (dd, J1¢,2¢ = 3.5 Hz, J2¢,3¢ = 10.0 Hz, 1 H, H-2¢), 3.23–3.68 (m, 6
H, OCH2CH2, CHHN, H-4¢, H-5¢), 3.94–4.31 (m, 7 H, 2 CH2Ph, H-
3, H-5, CHHN), 4.48 (dd, J5,6a = 5.7 Hz, J6a,6b = 11.9 Hz, 1 H, H-6a),
4.70 (dd, J5,6b = 4.0 Hz, J6a,6b = 11.9 Hz, 1 H, H-6b), 4.80 (d, J1,2
=
6.0 Hz, 1 H, H-1), 4.93 (d, J1¢,2¢ = 3.5 Hz, 1 H, H-1¢), 5.26–5.32 (m,
2 H, H-2, H-3¢), 5.54 (t, J3,4 = J4,5 = 7.6 Hz, 1 H, H-4), 6.95–8.00 (m,
25 H, 5 Ph).
Anal. Calcd for C53H52F3NO15: C, 63.66; H, 5.24; N, 1.40. Found:
C, 63.65; H, 5.40; N, 1.39.
3-Aminopropyla-D-Xylopyranosyl-(1→3)-b-D-glucopyranoside
(1)
To a solution of disaccharide 24 (120 mg, 0.12 mmol) in MeOH (3
mL) and EtOAc (2 mL) was added 10% Pd/C (10 mg). The mixture
was degassed, and the flask was filled with H2. The mixture was
stirred for 4 h, filtered through a Celite pad, and concentrated in vac-
MS (MALDI): m/z [M + Na]+ calcd for C72H72F3NO19: 1334.455:
found: 1334.460.
Synthesis 2007, No. 20, 3147–3154 © Thieme Stuttgart · New York

3154
V. Krylov et al.
PAPER
In addition, isomeric product 26b was isolated from the mixture.
1H NMR (500 MHz, D2O): d = 0.80 (t, J = 6.4 Hz, 3 H, CH3), 1.22
(m, 8 H, 4 CH2), 1.52, 1.77 (2 m, 4 H, 2 CH2), 2.17 (t, J = 7.2 Hz, 2
H, CH2), 3.22 (t, J = 6.7 Hz, 2 H, CH2CH2NH), 3.27–3.95 (m, 18 H,
H-2, H-5, H-2¢¢, H-3, H-4, H-6, H-2¢, H-4¢, H-5¢, H-3¢¢, H-5¢¢, H-3¢,
H-4¢¢, OCH2CH2), 4.40 (d, J1,2 = 8.0 Hz, 1 H, H-1), 5.26 (m, 2 H, H-
1¢, H-1¢¢).
13C NMR (125 MHz, D2O): d = 14.47 (CH3), 23.01 (CH2), 25.97
(CH2), 26.45 (CH2), 29.11 (CH2), 29.53 (CH2), 32.04 (CH2), 36.92
(CH2), 37.34 (CH2), 61.68 (C-6), 62.59, 62.70 (C-5¢, C-5¢¢), 69.02
(OCH2CH2), 70.48, 70.79, 71.16 (C-4, C-2¢, C-4¢, C-4¢¢), 72.77,
72.88 (C-2, C-2¢¢), 74.12 (C-3¢¢), 76.75 (C-5), 80.33 (C-3¢), 83.20
(C-3), 100.13, 100.33 (C-1¢, C-1¢¢), 103.48 (C-1), 178.40
(NHCOCH2).
Yield: 30 mg (15%).
1H NMR (250 MHz, CDCl3): d = 1.72 (m, 2 H, CH2CH2CH2), 1.94
(s, 3 H, CH3), 3.02 (dd, J1¢,2¢ = 3.2, J2¢,3¢ = 9.7 Hz, 1 H, H-2¢), 3.17 (t,
J
1¢¢,2¢¢ = J2¢¢,3¢¢ = 7.9 Hz, 1 H, H-2¢¢), 3.20–3.64 (m, 8 H, H-4¢, H-5¢, H-
4¢¢, H-5a¢¢, CH2CH2NH, OCHH¢CH2), 3.81–4.16 (m, 7 H, H-3, H-5,
H-3¢, H-5b¢¢, OCHH¢CH2, PhCH2), 4.40–4.75 (m, 11 H, H-1, H-6,
H-1¢, H-1¢¢, 3 PhCH2), 5.10 (t, J2¢¢,3¢¢ = J3¢¢,4¢¢ = 9.3, 1 H, H-3¢¢), 5.21
(t, J1,2 = J2,3 = 7.1 Hz, 1 H, H-2), 5.53 (t, J3,4 = J4,5 = 8.2 Hz, 1 H, H-
4), 6.95–8.10 (m, 35 H, 7 Ph).
3-Aminopropyl a-D-Xylopyranosyl-(1→3)-a-D-xylopyranosyl-
(1→3)-b-D-glucopyranoside (3)
Deprotection of compound 26a (100 mg, 0.076 mmol) as described
for the preparation of compound 1 gave the trisaccharide 3 as a salt
with AcOH. Yield: 28 mg (66%); [a]D 93 (c 0.5, H2O).
MS (MALDI): m/z [M + Na]+ calcd for C27H49NO15: 650.300;
found: 650.299.
1H NMR (500 MHz, D2O): d = 1.95 (s, 3 H, CH3), 2.03 (m, 2 H,
Acknowledgment
CH2CH2CH2), 3.16 (t, J = 7.0 Hz, 2 H, CH2CH2NH), 3.39 (t, J1,2
=
J2,3 = 8.0 Hz, 1 H, H-2), 3.47 (m, 1 H, H-5), 3.54 (dd, J1¢¢,2¢¢ = 3.8 Hz,
This work was supported by the Russian Foundation for Basic Re-
search (grant 05-03-08107) and the Russian Academy of Sciences
(1st Program of the Division of Chemistry and Material Sciences,
RAS). We thank Dr. Yu. E. Tsvetkov for helpful discussions.
J
2¢¢,3¢¢ = 9.6 Hz, 1 H, H-2¢¢), 3.57–3.74 (m, 8 H, H-3, H-4, H-6a, H-2¢,
H-4¢, H-5a¢, H-3¢¢, H-5a¢¢), 3.78–3.93 (m, 6 H, H-6b, H-3¢, H-5b¢, H-
5b¢¢, H-4¢¢, OCHH¢CH2), 4.09 (m, 1 H, OCHH¢CH2), 4.53 (d, J1,2
8.0 Hz, 1 H, H-1), 5.35 (m, 2 H, H-1¢, H-1¢¢).
=
13C NMR (125 MHz, D2O): d = 28.10 (CH2CH2CH2), 39.03
(CH2CH2NH), 61.95 (C-6), 62.93, 63.06 (C-5¢, C-5¢¢), 69.28
(OCH2CH2), 70.57, 70.84, 71.21 (C-4, C-2¢, C-4¢, C-4¢¢), 72.84,
72.90 (C-2, C-2¢¢), 74.21 (C-3¢¢), 76.85 (C-5), 80.36 (C-3¢), 83.17
(C-3), 100.21, 100.41 (C-1¢, C-1¢¢), 103.52 (C-1).
MS (MALDI): m/z [M]+ calcd for C19H36NO14: 502.214; found:
502.213.
References
(1) Minamida, S.; Aoki, K.; Natsuka, S.; Omichi, K.; Fukase,
K.; Kusumoto, S.; Hase, S. J. Biochem. (Tokyo) 1996, 120,
1002.
(2) Hase, S.; Kawabata, S.; Nishimura, H.; Takeya, H.;
Sueyoshi, T.; Miyata, T.; Iwanaga, S.; Takao, T.;
Shimonishi, Y.; Ikenaka, T. J. Biochem. (Tokyo) 1988, 104,
867.
(3) Bjoern, S.; Foster, D. C.; Thim, L.; Wieberg, F. C.;
Christensen, M.; Komiyama, Y.; Pedersen, A. H.; Kisiel, W.
J. Biol. Chem. 1991, 266, 11051.
(4) Moloney, D. J.; Shair, L.; Lu, F. M.; Xia, J.; Locke, R.;
Matta, K. L.; Haltiwanger, R. S. J. Biol. Chem. 2000, 275,
9604.
3-(Octanoylamino)propyl a-D-Xylopyranosyl-(1→3)-b-D-glu-
copyranoside (2)
A solution of disaccharide 1 as its acetate salt (10.0 mg, 0.023
mmol), N-(octanoyloxy)succinimide (6 mg, 0.026 mmol), and Et3N
(4.2 mL, 0.029 mmol) in anhyd DMF (0.4 mL) was kept for 1 h at
r.t. The mixture was concentrated and the product 2 was isolated
from the residue by chromatography on a Sephadex G-15 gel col-
umn. Yield: 8.1 mg (70%); [a]D 37 (c 0.5, MeOH).
(5) Fukase, K.; Hase, S.; Ikenaka, T.; Kusumoto, S. Bull. Chem.
Soc. Jpn. 1992, 65, 436.
1H NMR (500 MHz, D2O): d = 0.81 (t, J = 6.7 Hz, 3 H, CH3), 1.25
(m, 8 H, 4 CH2), 1.53, 1.77 (2 m, 4 H, 2 CH2), 2.17 (t, J = 7.2 Hz, 2
(6) Ustyuzhanina, N.; Komarova, B.; Zlotina, N.; Krylov, V.;
Gerbst, A.; Tsvetkov, Y.; Nifantiev, N. Synlett 2006, 921.
(7) Gerbst, A. G.; Ustuzhanina, N. E.; Grachev, A. A.;
Tsvetkov, D. E.; Khatuntseva, E. A.; Whitefield, D. M.;
Berces, A.; Nifantiev, N. E. J. Carbohydr. Chem. 2001, 20,
821.
(8) Ustyuzhanina, N.; Krylov, V.; Grachev, A.; Gerbst, A.;
Nifantiev, N. Synthesis 2006, 4017.
(9) Jenkins, D.; Potter, B. J. Chem. Soc., Perkin Trans. 1 1998,
41.
(10) Ogawa, T.; Yamamoto, H. Carbohydr. Res. 1985, 137, 79.
(11) Schmidt, R. R.; Kinzy, W. Adv. Carbohydr. Chem. Biochem.
1994, 50, 21.
(12) Duus, J. Ø.; Nifantiev, N.; Shashkov, A. S.; Khatunseva, E.
A.; Bock, K. Carbohydr. Res. 1996, 288, 25.
(13) Spijker, N. M.; van Boeckel, C. A. A. Angew. Chem., Int. Ed.
Engl. 1991, 30, 180; Angew. Chem. 1991, 103, 179.
(14) Lars, P.; Kund, J. J. Org. Chem. 2001, 66, 6268.
(15) Sushovie, B.; Vajtuer, Z.; Naumshi, R. Tetrahedron 1991,
47, 8407.
H, CH2), 3.24 (t, J = 7.0 Hz, 2 H, CH2CH2NH), 3.30 (t, J1,2 = J2,3
=
7.9 Hz, 1 H, H-2), 3.39 (m, 1 H, H-5), 3.46 (dd, J1¢,2¢ = 3.7 Hz,
J
2¢,3¢ = 9.3 Hz, 1 H, H-2¢), 3.53–3.70 (m, 7 H, H-3, H-4, H-6a, H-3¢,
H-4¢, H-5a¢, OCHH¢CH2), 3.77–3.95 (m, 3 H, H-6b, H-5b¢,
OCHH¢CH2), 4.40 (d, J1,2 = 8.0 Hz, 1 H, H-1), 5.25 (d, J1¢,2¢ = 3.7
Hz, 1 H, H-1¢).
13C NMR (125 MHz, D2O): d = 14.47 (CH3), 23.01 (CH2), 26.45
(CH2), 29.12 (CH2), 29.19 (CH2), 29.54 (CH2), 32.05 (CH2), 36.92
(CH2), 37.32 (CH2), 61.70 (C-6), 62.61 (C-5¢), 69.00 (OCH2CH2),
70.46 (C-4¢), 71.24 (C-4), 72.74, 72.89 (C-2, C-2¢), 74.13 (C-3¢),
76.75 (C-5), 83.04 (C-3), 100.18 (C-1¢), 103.50 (C-1), 178.38
(NHCOCH2).
MS (MALDI): m/z [M + Na]+ calcd for C22H41NO11: 518.257;
found: 518.258.
3-(Octanoylamino)propyl a-D-Xylopyranosyl-(1→3)-a-D-xylo-
pyranosyl-(1→3)-b-D-glucopyranoside (4)
Trisaccharide 3 (10.0 mg, 0.18 mmol) was N-octanoylated as de-
scribed for the preparation of 2 to give neoglycolipid 4. Yield: 8.3
mg (74%); [a]D 59 (c 0.5, MeOH).
(16) Armarego, W. L. F.; Chai, C. L. L. Purification of
Laboratory Chemicals, 5th ed.; Butterworth Heinemann:
Burlington, MA, 2003.
Synthesis 2007, No. 20, 3147–3154 © Thieme Stuttgart · New York