An efficient synthesis of a dimer of the tetrasaccharide present in motif B of the Mycobacterium tuberculosis cell wall

Article abstract of DOI:10.1055/s-2005-872674

An efficient method for the synthesis of 3,5-branched octaarabinoside, which is a dimer of the tetrasaccharide present in motif B of the Mycobacterium tuberculosis cell wall, has been developed by using 2,3,5-tri-O-benzoyl-α- D-arabinofuranosyl trichloroa

Full text of DOI:10.1055/s-2005-872674

LETTER
2267
An Efficient Synthesis of a Dimer of the Tetrasaccharide Present in Motif B of
the Mycobacterium tuberculosis Cell Wall
Efficient
Method
f
i
or the
S
a
ynthesis of
n
3,5-Branche
g
d Octaarabin
d
oside ong Mei,a Jun Ning*a,b
a
Research Center for Eco-Environmental Sciences, Academia Sinica, P. O. Box 2871, Beijing 100085, P. R. China
Fax +86(10)62923563; E-mail: jning@mail.rcees.ac.cn
b
Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100094, P. R. China
Received 12 July 2005
Several approaches have been taken with success for the
chemical synthesis of oligosaccharides.2 Most involve the
activation of the anomeric leaving group with a Lewis
acid and then displacement of that leaving group by the
Abstract: An efficient method for the synthesis of 3,5-branched
octaarabinoside, which is a dimer of the tetrasaccharide present in
motif B of the Mycobacterium tuberculosis cell wall, has been
developed by using 2,3,5-tri-O-benzoyl-a-D-arabinofuranosyl
trichloroacetimidate, 5-O-acetyl-2,3-di-O-benzoyl-a-D-arabino- free hydroxyl of the acceptor sugar. The Koenigs–Knor
furanosyl trichloroacetimidate, 1,2-O-isopropylidene-5-O-trityl-b-
D-arabinofuranose, dodecyl 2,3-di-O- benzoyl-a-D-arabinofurano-
side and phenyl 2,3-di-O-benzoyl-1-thio-a-D-arabinofuranoside as
synthons.
method of coupling glycosyl halides, one of the first
techniques to gain widespread usage, is still in common
use. Trichloroacetimidates,7 prepared by the reaction of
free sugar with trichloroacetonitrile and base, are used
most frequently for coupling, e.g. glycosyl sulfoxides,8
phosphates,9 and phosphates10 and thio-11 and pentenyl
glycosides.12
Key words: oligosaccharides, synthesis, glycosylations, stereo-
selectivity, glycosides
Mycobacterium (M.) tuberculosis, the causative agent of
tuberculosis, belongs to the mycobacteria.13 An impres-
sive feature of this genus of bacteria is that they synthesize
cell wall polysaccharides containing predominantly fura-
nose residues,13 whereas a similar phenomenon has never
been found in humans. For M. tuberculosis, the major
polysaccharides formed in its cell wall are an arabino-
galactan (AG) and a lipoarabinomannan (LAM) in which
all of the galactose and arabinose residues are present in
the furanose form.13 The organism’s ability to make these
polymers is critical to its survival, and therefore inter-
fering with the biosynthesis of these polysaccharides is an
approach for identifying anti-TB drugs.14
Saccharides have many key biological functions,1 when
conjugated to protein to form glycoproteins, they can alter
protein structure and function. As components of glyco-
lipids, they can play pivotal roles in cell–cell recognition
and signaling. The extracellular matrix contains proteo-
glycans, large glycoconjugates that not only modify the
physicochemical properties of the solution but also are
involved in many recognition processes. Although numer-
ous carbohydrate structures occur in nature, in general, the
role of saccharide structure in function has been minimal-
ly studied. This can be attributed mainly to the difficulty
of synthesizing saccharides. Unlike proteins and nucleic
acids, saccharides are more difficult to synthesize because
(i) the molecules are typically branched rather than linear,
(ii) the monosaccharide unites can be connected by a- or
b-linkages, and (iii) oligosaccharide synthesis requires
multiple selective protection and deprotection steps. Al-
though over the past few decades, considerable progress
has been made in this field,2 currently there is still no gen-
eral route for saccharide synthesis and glycosylation
chemistry is still not predicable or generally accessible.
To facilitate the synthesis of target oligosaccharides,
regio- and stereoselective glycosylation of glycosyl do-
nors with unprotected or partially protected sugar accep-
tors has been extensively studied. Employing this
strategy, in the last few years, we have prepared a lot of
oligosaccharides with various structures present in natural
sources such as 3,6-branched gluco-oligosaccharides,3
2,6-branched manno-oligosaccharides,4 2,6-branched,5
3,6-branched and 5,6-branched galacto-oligasaccharides.6
Five major motifs called A, B, C, D, and E, which are
linked to the terminal ends of AG and/or LAM, have been
isolated and characterized15 as shown in Figure 1. These
oligosaccharides may play an important role in the surviv-
al and pathogenicity of the organism. Since these oli-
gosaccharides are not present in humans, they tend to be
highly antigenic in the human immune system. Besides, it
has been demonstrated recently that one of the anti-TB
drugs used to treat tuberculosis (ethambutol) for the last
35 years actually acts by inhibiting the biosynthesis of
arabinan portions of LAM and AG.16
Providing sufficient quantities of a sample is a basic pre-
requisite for detailed studies on a compound’s fundamen-
tal biochemical properties and possible biological
functions. However, it is very difficult to gain arabinose-
containing oligosaccharides with clear structural informa-
tion for biological studies from natural sources. So there
has been much interest in the synthesis of the components
of the M. tuberculosis cell wall polysaccharides. The
preparations of motifs A, B, C, D, and E oligosaccharide
derivatives have been finished recently.6b,17 Compound 6,
SYNLETT 2005, No. 15, pp 2267–2272
1
9
.0
9
.2
0
0
5
Advanced online publication: 07.09.2005
DOI: 10.1055/s-2005-872674; Art ID: U22205ST
© Georg Thieme Verlag Stuttgart · New York

2268
X. Mei, J. Ning
LETTER
O
HO
O
O
HO
HO
O
HO
HO
O
OH
O
O
O
OH
O
OH
O
OH
HO
HO
O
HO
HO
O
O
HO
O
HO
O
OH
O
O
HO
HO
HO
O
O
OH
HO
OH
O
OH
OH
O
HO
OH
motif C (3)
motif B (2)
motif A (1)
O
O
O
HO
O
O
HO
OH
OH
OH
O
O
O
OH
O
OH
OH
OH
O
OH
HO
HO
OH
motif D (4)
HO
HO
motif E (5)
OH
O
HO
HO
O
O
OH
HO
O
HO
O
O
HO
HO
O
O
O
OH
OH
HO
O
O
OH
HO
O
HO
O
O
HO
HO
O
OC12H25
OH
OH
6
Figure 1
a dimer of the tetrasaccharide present in Motif B, is one of and phenyl 2,3-di-O-benzoyl-1-thio-a-D-arabinofurano-
the arabinose-containing oligosaccharides. For detailed side (18) were the basic building materials. Compound 8
characterization of AG and LAM, especially for further was obtained according to the standard method.18
elucidation of the molecular structure responsible for their Compound 10 was prepared by tritylation of D-arabinose,
biological properties, it would be necessary to synthesize followed by 1,2-O-isopropylation.19 Tritylation of D-ara-
compound 6. This, together with the fact that the synthesis binose followed by benzoylation in a one-pot manner
of 6 was not previously reported, prompted us to synthe- gave 1,2,3-tri-O-benzoyl-5-O-trityl-a-D-arabinofuranose
size the octasaccharide using a ‘4+4’ strategy.
(11) in 71% yield for two steps (Scheme 1). Selective
acetolysis of 11 using CH2Cl2–AcOH–Ac2O–H2SO4 in a
ratio of 15:10:10:1 afforded the corresponding 1,5-diace-
tate 12 in 83% yield. The diacetate 12 was selectively
deacetylated at the anomeric position with benzylamine in
THF in high yield (88%) to give the corresponding 5-O-
acetyl-2,3-di-O-benzoyl-a-D-arabinofuranose (13).
To complete the synthesis of target molecule 6, we de-
signed a convergent strategy using tetrasaccharide 28 as
acceptor and tetrasaccharide thioglycoside 26 as donor,
which were assembled by the building blocks 8, 10, 14, 16
and 8, 10, 14, 18, respectively.
In our synthesis, 2,3,5-tri-O-benzoyl-a-D-arabinofurano-
syl trichloroacetimidate (8), 1,2-O-isopropylidene-5-O-
trityl-b-D-arabinofuranose (10), 5-O-acetyl-2,3-di-O-
benzoyl-a-D-arabinofuranosyl trichloroacetimidate (14),
dodecyl 2,3-di-O-benzoyl-a-D-arabinofuranoside (16)
Subsequent reaction of 13 with CCl3CN/K2CO3 in CH2Cl2
afforded glycosyl donor 14. Coupling of 14 with dodecyl
alcohol gave compound 15 which was selectively con-
verted to 16 using MeOH containing 0.1% HCl. The solu-
tion of MeOH containing HCl was formed in situ by
Synlett 2005, No. 15, 2267–2272 © Thieme Stuttgart · New York

LETTER
Efficient Method for the Synthesis of 3,5-Branched Octaarabinoside
2269
O
O
O
O
TrO
AcO
HO
O
BzO
TrO
HO
b
a
O
OH
OH
OH
OH
BzO
OCNHCCl3
OH
OH
OBz
OH
10
9
8
7
O
O
O
AcO
TrO
O
HO
e
OH
BzO
c
d
BzO
BzO
OH
OH
OAc
OBz
OBz
13
OBz
12
OBz
11
OH
7
O
O
BzO
AcO
i
BzO
OC12H2
OC12H25
OBz
16
O
OBz
15
AcO
g
h
f
BzO
OC(NH)CCl3
OBz
14
O
O
HO
AcO
BzO
i
BzO
SPh
SPh
OBz
18
OBz
17
Scheme 1 Reagents and conditions: (a) TrCl (1.2 equiv), pyridine, 40 °C, 48 h, 64%; (b) Me2C(OMe)2, TsOH·H2O, acetone, r.t., 1.5 h, 88%;
(c) i. TrCl (1.2 equiv), pyridine, 40 °C, 48 h; ii. PhCOCl (3.6 equiv), r.t., 24 h, 71% (for twe steps); (d) CH2Cl2–HOAc–Ac2O–
H2SO4 = 15:10:10:1, r.t., 12 h, 83%; (e) BnNH2 (4.0 equiv), THF, r.t., 24 h, 88%; (f) CH2Cl2, CCl3CN (3.3 equiv), K2CO3 (5 equiv), r.t., 12 h,
86%; (g) dodecyl alcohol (2 equiv), TMSOTf (0.05 equiv), CH2Cl2, r.t., 3 h, 89%; (h) PhSH (1.5 equiv), TMSOTf (0.05 equiv), CH2Cl2,
r.t., 2 h, 88%; (i) MeOH–HCl (0.1%), r.t., 12–14 h, 93% for 16, 94% for 18.
adding acetyl chloride to MeOH. Compound 18 was Anomeric carbons in a-arabinofuranosides resonate be-
prepared from 14 and thiophenol in a similar fashion to tween d = 105 and 110 ppm, and those of b-arabino-
that of making 16.
furanosides resonate between d = 100 and 104 ppm.22
Therefore, the anomeric stereochemistry of the glycosyl
residues in 6 could be determined unequivocally by 13C
NMR spectroscopy. The 13C NMR spectrum showed eight
anomeric carbons at d = 107.66, 107.61, 107.59, 107.55,
107.52, 107.43, 107.25, and 107.18 ppm, indicative of the
a-linkages of all arabinofuranosyl residues in 6.
Coupling of 8 with 10 followed by detritylation with solid
FeCl3·6H2O (commercial product, without any pretreat-
ment) in CH2Cl220 gave disaccharide glycosyl acceptor 20
in 72% yield for two steps (Scheme 2). Coupling of 20
with glycosyl donor 14 using TMSOTf as catalyst and 4
Å molecular sieves in CH2Cl2 afforded trisaccharide 21 in
91% yield. Removal of the 1,2-O-isopropylidene group of All new compounds involved in this study were identified
21 in 80% AcOH followed by acetylation with acetic by optical rotations, 1H NMR or/and 13C NMR spectros-
anhydride in pyridine, selective 1-O-deacetylation with copy, and elemental analyses or MALDI-TOF MS. Se-
benzylamine in THF, and subsequent treatment with lected physical data for some key compounds are given in
CCl3CN/K2CO3 afforded the desired trisaccharide the references.23
glycosyl donor 25 in 71% yield for four steps.
In all of the synthesis, very easily accessible materials and
Condensation of 25 with 18 afforded tetrasaccharide cheap reagents were used and the reactions were carried
thioglycoside donor 26 in 91% yield. Condensation of 25 out smoothly in high yields and in large scales. In the syn-
with 16 afforded tetrasaccharide 27 in 91% yield. Selec- thesis, several intermediates were not separated and used
tive 5-O-deacetylation of 27 in MeCOCl–MeOH–CH2Cl2 directly for the further reaction simplifying the operation
(1:500:500) gave tetrasaccharide acceptor 28 in 88% substantially. The sole use of acyl groups in the synthesis
yield.21
further simplified the procedure.
Condensation of 26 with 28 afforded octasaccharide block
29 in 85% yield (Scheme 3). Deprotection of 29 using
NH3 in MeOH gave free octasaccharide 6 as an amor-
phous white solid in 90% yield.
Acknowledgment
This work was supported by the National Key Project for Basic
Research (2003CB114400) and by the Excellent Scientist Project
from the Chinese Academy of Agricultural Sciences.
Synlett 2005, No. 15, 2267–2272 © Thieme Stuttgart · New York

2270
X. Mei, J. Ning
LETTER
O
O
AcO
AcO
BzO
BzO
O
O
RO
O
O
O
O
O
O
OBz
OBz
a
O
14
c
BzO
HO
O
OH
8 + 10
BzO
a
O
O
BzO
BzO
O
BzO
OBz
OBz
O
O
19 R = Tr
OBz
OBz
b
22
21
20 R = H
O
AcO
O
AcO
BzO
BzO
O
O
O
OBz
O
OBz
f
d
AcO
OR
AcO
O
BzO
O
BzO
OC(NH)CCl3
BzO
BzO
O
O
OBz
OBz
23 R = Ac
25
e
24 R = H
16
18
a
a
O
O
AcO
RO
BzO
BzO
O
O
O
O
OBz
OBz
AcO
AcO
O
O
BzO
BzO
O
O
O
O
BzO
BzO
BzO
BzO
O
O
SPh
OC12H25
OBz
OBz
OBz
OBz
27 R = Ac
28 R = H
g
26
Scheme 2 Reagents and conditions: (a) TMSOTf (0.02 equiv), MS 4 Å, CH2Cl2, –42 °C, 3 h, 91%; (b) FeCl3·6H2O (1.5 equiv), CH2Cl2, r.t.,
2 h, 81%; (c) 80% HOAc, reflux, 4 h, 90%; (d) Ac2O, pyridine, r.t., 12 h, 98%; (e) BnNH2 (4.0 equiv), THF, r.t., 24 h, 90%; (f) CH2Cl2, CCl3CN
(3.3 equiv), K2CO3 (5 equiv), r.t., 12 h, 90%; (g) MeCOCl–MeOH–CH2Cl2 (1:500:500), r.t., 12 h, 88%.
(10) Hashimoto, S. J. Chem. Soc., Chem. Commun. 1989, 685.
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Synlett 2005, No. 15, 2267–2272 © Thieme Stuttgart · New York

LETTER
Efficient Method for the Synthesis of 3,5-Branched Octaarabinoside
2271
O
AcO
BzO
O
O
OBz
AcO
O
BzO
O
O
BzO
BzO
O
b
O
O
6
OBz
a
OBz
BzO
26 + 28
O
O
OBz
AcO
O
BzO
O
O
BzO
BzO
O
OC12H25
OBz
OBz
29
Scheme 3 Reagents and conditions: (a) NIS (1.5 equiv), TMSOTf (0.02 equiv), MS 4 Å, CH2Cl2, –42 °C, 3 h, 85%; (b) MeOH sat. with
anhyd NH3, r.t., 72 h, 90%.
(17) (a) Gurjar, M. K.; Hotha, S.; Mereyala, H. B. Chem.
Commun. 1998, 685. (b) D’Souza, F. W.; Lowary, T. L.
Org. Lett. 2000, 2, 1493. (c) D’Souza, F. W.; Ayers, J. D.;
McCarren, P. R.; Lowary, T. L. J. Am. Chem. Soc. 2000,
122, 1251. (d) Sanchez, S.; Bamhoud, T.; Prandi, J.
Tetrahedron Lett. 2000, 41, 7447. (e) Gurjar, M. K.; Reddy,
L. K.; Hotha, S. Org. Lett. 2001, 3, 321. (f) Gurjar, M. K.;
Reddy, L. K.; Hotha, S. J. Org. Chem. 2001, 66, 4657.
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Carbohydr. Res. 2003, 338, 581.
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1996, 280, 287.
(20) Ding, X.; Wang, W.; Kong, F. Carbohydr. Res. 1997, 303,
445.
For 20: [a]D +44.7 (c 1.0, CHCl3). 1H NMR (400 MHz,
CDCl3): d = 8.06–7.26 (m, 15 H, 3 × PhH), 5.96 (d, 1 H,
J3,4 = 4.1 Hz, H-3), 5.61 (d, 1 H, J = 4.6 Hz, H-2), 5.50 (d, 1
H, J = 1.2 Hz, H-1), 5.45 (s, 1 H, H-1), 4.81 (dd, 1 H, J = 3.7,
11.9 Hz, H-5), 4.74 (d, 1 H, J = 3.9 Hz, H-3), 4.68 (dd, 1 H,
J = 4.7, 11.9 Hz, H-5), 4.58 (m, 1 H, H-5), 4.35 (d, 1 H,
J = 3.2 Hz, H-2), 4.24 (m, 1 H, H-4), 3.80 (m, 2 H, H-4, H-
5), 1.53, 1.34 (2 s, 6 H, 2 CH3). Anal. Calcd for C35H38O12:
C, 64.61; H, 5.89. Found: C, 64.50; H, 5.74.
For 21: [a]D +21.9 (c 1.0, CHCl3). 1H NMR (400 MHz,
CDCl3): d = 8.06–7.26 (m, 25 H, 5 × PhH), 5.94 (d, 1 H, H-
1), 5.59 (d, 1 H, J = 4.8 Hz, H-3), 5.50 (d, 1 H, J = 1.1 Hz,
H-2), 5.45 (d, 1 H, J = 1.2 Hz, H-2), 5.38 (d, 1 H, J = 4.1 Hz,
H-3), 5.31 (s, 1 H, H-1), 5.27 (s, 1 H, H-1), 4.72–4.51 (m, 6
H, H-2, H-4, 4 × H-5), 4.46 (d, 1 H, J = 3.5 Hz, H-3), 4.36
(m, 1 H, H-4), 4.28 (m, 1 H, H-4), 4.04 (dd, 1 H, J = 5.4, 10.4
Hz, H-5), 3.75 (dd, 1 H, J = 4.6, 10.4 Hz, H-5), 2.02 (s, 3 H,
CH3CO), 1.56, 1.34 [2 s, 6 H, C(CH3)2]. Anal. Calcd for
C57H58O19: C, 65.38; H, 5.58. Found: C, 65.49; H, 5.41.
For 25: [a]D +34.4 (c 1.0, CHCl3). 1H NMR (400 MHz,
CDCl3): d = 8.56 (s, 1 H, CNHCCl3), 8.04–7.26 (m, 25 H,
5 × PhH), 6.37 (s, 1 H, H-1), 5.58 (d, 1 H, J = 4.8 Hz, H-3),
5.54 (d, 1 H, J = 1.1 Hz, H-2), 5.49 (d, 1 H, J = 1.2 Hz, H-2),
5.37 (d, 1 H, J = 4.1 Hz, H-3), 5.30 (s, 1 H, H-1), 5.28 (m, 1
H, H-2), 5.24 (s, 1 H, H-1), 4.76–4.50 (m, 6 H, H-3, H-4,
4 × H-5), 4.34 (m, 1 H, H-4), 4.11 (m, 1 H, H-4), 3.90 (dd,
1 H, J = 5.1, 10.4 Hz, H-5), 3.80 (dd, 1 H, J = 4.8, 10.4 Hz,
H-5), 2.02, 2.00 (2 s, 6 H, 2 × CH3CO). Anal. Calcd for
C59H56Cl3NO20: C, 58.79; H, 4.68. Found: C, 59.88; H, 5.24.
For 26: [a]D +20.1 (c 1.0, CHCl3). 1H NMR (400 MHz,
CDCl3): d = 8.04–7.26 (m, 40 H, 8 × PhH), 5.80 (s, 1 H, H-
1), 5.72 (d, 1 H, J = 4.1 Hz, H-3), 5.61 (m, 1 H, H-2), 5.53
(d, 1 H, J = 1.1 Hz, H-2), 5.47–5.45 (m, 3 H, H-1, H-2, H-3),
5.37 (s, 1 H, H-1), 5.34 (d, 1 H, J = 3.7 Hz, H-3), 5.27 (d, 1
H, J = 1.2 Hz, H-2), 5.21 (s, 1 H, H-1), 4.74 (dd, 1 H, J = 3.5,
11.9 Hz, H-5), 4.65–4.33 (m, 8 H, H-3, 4 H-4, 3 × H-5), 4.18
(dd, 1 H, J = 4.0, 11.9 Hz, H-5), 4.05 (dd, 1 H, J = 4.1, 11.9
Hz, H-5), 3.88 (m, 2 H, 2 × H-5), 2.01, 1.97 (2 × s, 6 H, 2 ×
CH3CO). 13C NMR (100 MHz, CDCl3): d = 170.60, 169.94
(2 × CH3CO), 165.96, 165.63, 165.57, 165.35, 165.31,
164.96, 164.91 (7 × PhCO), 105.97, 105.69, 105.46, 91.09
(4 × C-1), 20.68, 20.67 (2 × CH3CO). Anal. Calcd for
(21) Zeng, Y.; Li, A.; Kong, F. Tetrahedron Lett. 2003, 44, 8325.
(22) Mizutani, K.; Kasai, R.; Nakamura, M.; Tanaka, O.;
Matsuura, H. Carbohydr. Res. 1989, 185, 27.
(23) All new compounds gave satisfactory elemental analysis
results. Selected physical data for some key compounds are
as follows:
For 14: [a]D +80.9 (c 1.0, CHCl3). 1H NMR (400 MHz,
CDCl3): d = 8.73 (s, 1 H, CNHCCl3), 8.13–7.26 (m, 10 H,
2 × PhH), 6.64 (s, 1 H, H-1), 5.78 (d, 1 H, J2,3 = 1.1 Hz, H-
2), 5.51 (dd, 1 H, J2,3 = 1.1 Hz, J3,4 = 3.3 Hz, H-3), 4.68 (m,
1 H, H-4), 4.58 (dd, 1 H, J4,5a = 4.2 Hz, J5a,5b = 11.9 Hz, H-
5a), 4.44 (dd, 1 H, J4,5b = 5.51 Hz, J5a,5b = 11.9 Hz, H-5b),
2.04 (s, 3 H, CH3CO). Anal. Calcd for C24H22Cl3NO8: C,
51.59; H, 3.97. Found: C, 51.74; H, 3.86.
For 16: [a]D +98.1 (c 1.0, CHCl3). 1H NMR (400 MHz,
CDCl3): d = 8.09–7.26 (m, 10 H, 2 × PhH), 5.52 (d, 1 H,
J2,3 = 1.2 Hz, H-2), 5.42 (m, 1 H, H-3), 5.24 (s, 1 H, H-1),
4.31 (m, 1 H, H-4), 4.02–3.97 (m, 2 H, CH2C11H23), 3.75 (m,
1 H, 5a), 3.53 (m, 1 H, 5b), 1.65–0.82 (m, 23 H, CH2C11H23).
Anal. Calcd for C32H44O7: C, 71.08; H, 8.20. Found: C,
71.44; H, 8.06.
For 18: [a]D +101.1 (c 1.0, CHCl3). 1H NMR (400 MHz,
CDCl3): d = 8.14–7.26 (m, 15 H, 3 × PhH), 5.80 (s, 1 H, H-
1), 5.74 (d, 1 H, J2,3 = 1.4 Hz, H-2), 5.55 (d, 1 H, J3,4 = 4.6
Hz, H-3), 4.59 (m, 1 H, H-4), 4.04 (m, 2 H, H-5a,b). Anal.
Calcd for C26H24O6S: C, 67.22; H, 5.21. Found: C, 67.04; H,
5.06.
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X. Mei, J. Ning
LETTER
C83H78O25S: C, 66.13; H, 5.22. Found: C, 66.41; H, 5.04.
For 27: [a]D +69.4 (c 1.0, CHCl3). 1H NMR (400 MHz,
CDCl3): d = 8.03–7.22 (m, 35 H, 7 × PhH), 5.59 (d, 1 H, J =
4.6 Hz, H-3), 5.53 (d, 1 H, H-2), 5.48 (s, 1 H, H-1), 5.46 (d,
1 H, J = 4.6 Hz, H-3), 5.44 (d, 1 H, J = 1.2 Hz, H-2), 5.41 (d,
1 H, J = 1.1 Hz, H-2), 5.37 (s, 1 H, H-1), 5.34 (d, 1 H, J = 3.4
Hz, H-3), 5.28 (d, 1 H, J = 1.3 Hz, H-2), 5.21 (d, 2 H, J = 4.7
Hz, 2 × H-1), 4.73 (dd, 1 H, J = 3.6, 11.6 Hz, H-5), 4.63 (m,
1 H, H-5), 4.53–4.33 (m, 7 H, H-3, 2 × H-4, 2 × H-5,
CH2C11H23), 4.13 (m, 1 H, H-5), 4.05 (dd, 1 H, J = 3.9, 11.6
Hz, H-5), 3.91 (dd, 1 H, J = 3.1, 11.6 Hz, H-5), 3.83 (dd, 1
H, J = 2.8, 11.9 Hz, H-5), 3.74 (m, 1 H, H-4), 3.49 (m,1 H,
H-4), 2.00, 1.98 (2 × s, 6 H, 2 × CH3CO), 1.61–0.82 (m, 23
H, CH2C11H23). Anal. Calcd for C89H98O26: C, 67.50; H,
6.24. Found: C, 67.66; H, 6.09.
11.2 Hz, H-5), 3.74 (m, 1 H, H-4), 3.50 (m,1 H, H-4), 2.00
(s, H, CH3CO), 1.60–0.86 (m, 23 H, CH2C11H23). 13C NMR
(100 MHz, CDCl3): d = 169.92 (CH3CO), 166.16, 165.90,
165.67, 165.54, 165.42, 165.01, 164.86 (7 × PhCO), 105.74,
105.46, 105.41, 105.42 (4 × C-1), 20.67 (CH3CO). Anal.
Calcd for C87H96O25: C, 67.78; H, 6.28. Found: C, 67.60; H,
6.41.
For 29: [a]D +69.4 (c 1.0, CHCl3). 1H NMR (400 MHz,
CDCl3): d = 8.01–7.26 (m, 70 H, 14 × PhH), 5.51 (s, H-1),
5.50 (s, H-1), 5.45–5.40 (m, 3 H, H-1), 5.33 (s, H-1), 5.45–
5.40 (m, 2 H, H-1), 1.99, 1.97, 1.95 (3 × s, 9 H, 3 × CH3CO),
1.57–0.85 (m, 23 H, CH2C11H23). 13C NMR (100 MHz,
CDCl3): d = 170.58, 169.98, 169.91 (3 × CH3CO), 165.93,
169.94, 165.62, 165.63, 165.55, 165.51, 165.49, 165.41,
165.42, 165.12, 165.04, 164.93, 164.88, 164.84 (14 ×
PhCO), 106.03, 105.92, 105.79, 105.61, 105.59, 105.52,
105.47, 105.42 (8 × C-1), 20.70, 20.69, 20.66 (3 × CH3CO).
Anal. Calcd for C164H168O50: C, 67.02; H, 5.76. Found: C,
67.11; H, 5.60.
For 28: [a]D +74.4 (c 1.0, CHCl3). 1H NMR (400 MHz,
CDCl3): d = 8.04–7.26 (m, 35 H, 7 × PhH), 5.60 (d, 1 H,
J = 4.6 Hz, H-3), 5.57 (d, 1 H, J = 1.3 Hz, H-2), 5.4 (m, 2 H,
H-1, H-3), 5.43 (d, 1 H, J = 1.2 Hz, H-2), 5.40 (d, 1 H,
J = 1.1 Hz, H-2), 5.35 (m, 2 H, H-1, H-3), 5.29 (d, 1 H, 1.4
Hz, H-2), 5.22 (s, 1 H, H-1), 5.21 (s, 1 H, H-1), 4.78 (dd, 1
H, J = 3.6, 11.9 Hz, H-5), 4.65 (dd, 1 H, J = 4.6, 11.9 Hz, H-
5), 4.59 (m, 1 H, H-4), 4.50 (m, 1 H, H-4), 4.38–4.32 (m, 3
H, H-3, 2 × H-5), 4.16 (dd, 1 H, J = 4.3, 11.2 Hz, H-5), 3.99–
3.92 (m, 4 H, 2 × H-5, CH2C11H23), 3.84 (dd, 1 H, J = 3.5,
For 6: [a]D –18.9 (c 1.0, H2O). 1H NMR (400 MHz, D2O):
d = 5.16 (s, 2 H, H-1), 5.10 (s, 5 H, H-1), 4.96 (s, 1 H, H-1).
1.62–0.90 (m, 23 H, CH2C11H23). 13C NMR (100 MHz,
CDCl3): d = 107.66, 107.61, 107.59, 107.55, 107.52, 107.43,
107.25, 107.18 (8 × C-1). MALDI-TOF MS: m/z calcd for
C60H106O33: 1355.46 [M], found: 1378.09 [M + Na]+.
Synlett 2005, No. 15, 2267–2272 © Thieme Stuttgart · New York