Preparation of the pentasaccharide hapten of the GPL of Mycobacterium avium serovar 19 by achieving the glycosylation of a tertiary hydroxyl group

Article abstract of DOI:10.1016/j.carres.2006.04.038

The chemical synthesis of the glycopeptidolipid-type pentasaccharide hapten of Mycobacterium avium serovar 19 with a trifluoroacetamido spacer at the reducing end is described. The spacer-armed pentasaccharide 31, when conjugated to an immunogenic protein

Full text of DOI:10.1016/j.carres.2006.04.038

Carbohydrate Research 341 (2006) 1312–1321
Preparation of the pentasaccharide hapten of the GPL of
Mycobacterium avium serovar 19 by achieving the
glycosylation of a tertiary hydroxyl group
a
a
b
a
a,c,
*
´
´
´
´
´
´
Aniko Fekete, Katalin Gyergyoi, Katalin E. Kover, Istvan Bajza and Andras Liptak
¨
aResearch Group for Carbohydrates of the Hungarian Academy of Sciences, PO Box 94, H-4010 Debrecen, Hungary
bInstitute of Inorganic and Analytical Chemistry, University of Debrecen, PO Box 21, H-4010 Debrecen, Hungary
cInstitute of Biochemistry, University of Debrecen, PO Box 55, H-4010 Debrecen, Hungary
Received 24 January 2006; received in revised form 13 April 2006; accepted 20 April 2006
Available online 18 May 2006
Dedicated to Professor Dr. Richard R. Schmidt on the occasion of his 70th birthday
Abstract—The chemical synthesis of the glycopeptidolipid-type pentasaccharide hapten of Mycobacterium avium serovar 19 with a
trifluoroacetamido spacer at the reducing end is described. The spacer-armed pentasaccharide 31, when conjugated to an immuno-
genic protein, can be applied to the serodiagnosis of mycobacterial infections. The questionable structure of the penultimate
monosaccharide unit was clarified as 6-deoxy-3-C-methyl-2,4-di-O-methyl-L-mannopyranose. The occurrence of the 6-deoxy-3-C-
methyl-2,4-di-O-methyl-L-talopyranose could be excluded by the presence of the large H-10–H-20 coupling constant, which proves
4
the C1 (L) conformation as the favoured one.
ꢀ 2006 Elsevier Ltd. All rights reserved.
Keywords: Mycobacteria; Hapten; Oligosaccharides
1. Introduction
The structural elucidation2 of the pentasaccharide (1,
Fig. 1) left one question open: the stereochemistry at C-4
of the fourth monosaccharide unit. It could have either
the L-rhamno- or 6-deoxy-L-talo-configuration. The
other delicate structural characteristic of the pentasac-
charide is that the tertiary hydroxyl group is glycosyl-
ated. To the best of our knowledge, this is the first
example of the existence of such a structural unit among
naturally occurring oligosaccharides and no synthetic
methodology has been developed for its preparation.
The cell-surface antigen of Mycobacterium avium sero-
var 19 consists of a pentasaccharide chain and a peptido-
lipid aglycone moiety, which is anchored in the cell
membrane.1 Some mycobacteria are the so-called
opportunistic microorganisms and because they cause
serious infections among the immunocompromised per-
sons, mainly among the victims of AIDS, fast and reli-
able serodiagnosis of the infections is an important
clinical task. These immunological events are deter-
mined by the carbohydrate part of the cell-surface anti-
gens and thus the synthesis of these outer chains, or
nonreducing oligosaccharide fragments of them, are also
of interest.
2. Results and discussion
Our intention was to prepare the pentasaccharide using a
3+2 block strategy (Scheme 1). Earlier we have reported
the synthesis of the two possible penultimate units,
namely methyl 6-deoxy-3-C-methyl-2,4-di-O-methyl-a-
L-mannopyranoside (2) and its C-4 epimer methyl 6-
deoxy-3-C-methyl-2,4-di-O-methyl-a-L-talopyranoside
*
Corresponding author. Tel.: +36 52 512900/22256; fax: +36 52
512913; e-mail: liptaka@puma.unideb.hu
0008-6215/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2006.04.038

A. Fekete et al. / Carbohydrate Research 341 (2006) 1312–1321
1313
deprotected with hydrazine acetate in DMF to yield
hemiacetal 14. The trichloroacetimidate 4 was obtained
from 14 using standard procedures.7 We used TMSOTf7
for the activation of the trichloroacetimidate 4 (Scheme
3). Thus, reaction of the donor 4 with acceptor 2
resulted in the disaccharide 5, containing a b-interglyco-
sidic linkage, in a yield of 42%.
However, when this reaction was attempted in the
case of acceptor 3, we isolated two products (Scheme
4). After NMR spectroscopic investigations, it was evi-
dent that both were disaccharides, one with the a (6a,
25%) and the other with the desired b (6b, 34%) intergly-
cosidic linkage, despite the presence of the participating
substituent at C-2. In addition to the well-known factors
(the type of the leaving group at the anomeric centre, the
promoter, the substituents on the carbohydrates, the
solvent and the temperature) unfavourable steric inter-
actions between the glycosyl donor and the acceptor
may influence the stereochemical outcome (a/b ratio)
of glycosylations.9 In our case, acceptor 3 is an extre-
mely overcrowded compound in which four rather bulky
substituents are present in a 1,3-cis-diaxial arrangement.
We observed another structural feature of compounds
6a and 6b: the change in conformation of the 6-deoxy-
Talp unit. Having measured the 1H–1H coupling
constants, it was clear that the ring possessed the
4C1 (L), not 1C4 (L), conformation. For the explana-
tion of this phenomenon, we synthesized each of the
methyl ethers of the two sugars and compared their
Figure 1. Structure of the pentasaccharide hapten of the serovariant 19
of the Mycobacterium avium complex.
(3),3 the thioglycoside acceptor 7, and the Rhap!6-
deoxy-Talp (10) disaccharide glycosyl acceptor.4
For the synthesis of the disaccharides at the nonreduc-
ing end, we used 2,6-di-O-acetyl-3,4-di-O-methyl-b-D-
glucopyranosyl trichloroacetimidate (4) as the glycosyl
donor, which was prepared as follows (Scheme 2).
Treatment of the 3,4-di-O-methyl-D-glucopyranose
(12)5 with acetic anhydride in pyridine gave the triace-
tate 13. The anomeric acetyl group was selectively
Scheme 1. Synthetic plan for target pentasaccharide 11.
Scheme 2. Reagents and conditions: (a) Ac2O, pyridine, rt, 86%; (b) hydrazine acetate, DMF, rt, 92%; (c) trichloroacetonitrile, K2CO3, CH2Cl2, rt,
61%.

1314
A. Fekete et al. / Carbohydrate Research 341 (2006) 1312–1321
methyl ester 17. For the further transformation of 6b,
we had to choose another sequence: we used TEMPO-
mediated selective oxidation13 of the diol 21 (Scheme
6). Treatment of 6b with catalytic sodium methoxide
showed no selectivity in spite of the fact that the 20-
OAc was isolated and a bulky aglycone was also pres-
ent.11 Thus, treatment of 21 with TEMPO/NaOCl gave
22, which was transformed to its methyl ester 23 with
methyl iodide in DMF.
Scheme 3. Reagents and conditions: (a) TMSOTf, CH2Cl2, ꢀ50 ꢁC,
42%.
Because there were substantial differences in the NMR
data of compounds 5, 6b and 17, 23, the comparison of
the spectra of our two synthetic disaccharides with the
spectrum of the native saccharide could eliminate the
uncertainty in the structure. However, one more ques-
tion had to be answered: does the conformation of the
6-deoxy-Talp unit change when the methyl aglycone is
replaced by a sugar ring?
Disaccharides 17 and 23 were thus transformed into
glycosyl donors 20 and 26, respectively, through acetol-
ysis of the methyl aglycone (!18, !24). This reaction
had to be carried out under mild conditions to prevent
the cleavage of the interglycosidic bond. For the selec-
tive anomeric deprotection of 19, hydrazine acetate14
was used; however, applying the same conditions for
acetate 24 gave the hemiacetal 25 in low yield. Of several
other methods for the selective anomeric deacetylation,
the use of dibutyltin oxide15 proved to be the best. In
the next steps, glycosyl trichloroacetamidates 20 and
26 were prepared under standard conditions7 from
hemiacetals 20 and 25. The TMSOTf-activated glycosyl-
ation of the thioglycoside acceptor 74 with 20 and 26 re-
sulted in trisaccharides 8 (35%) and 9 (26%), respectively
(Scheme 7).
The NMR data of these two trisaccharides are listed
in Table 1. It should be noted that compounds having
the 6-deoxy-Talp unit as a building block were more sen-
sitive than their Rhap-analogues and decomposed on
standing. Because it was evident from the NMR data
of 9 that the replacement of the methyl aglycone by a
sugar residue has no effect on the conformation of the
6-deoxy-Talp unit, and because the NMR data for
Scheme 4. Reagents and conditions: (a) TMSOTf, CH2Cl2, ꢀ50 ꢁC,
25% for 6a and 34% for 6b.
conformational properties. All of the methyl 6-deoxy-3-
C-methyl-a-L-mannopyranoside derivatives adopt the
1C4 (L) conformation. The situation in the case of the
methyl 6-deoxy-3-C-methyl-a-L-talopyranoside deriva-
tives is different: for the fully substituted glycosides the
4C1 (L) conformation is predominant. However, it is to
be noted that all of the mono- and disubstituted talo-
1
pyranoside derivatives exist exclusively in the C4 (L)
conformation.10
The next step in our strategy was oxidation at the po-
sition 60 in disaccharides 15 and 21 (Scheme 5). Thus
compound 5 was treated with catalytic sodium methox-
ide in methanol to obtain the selectively 6-O-deprotected
15,11 which was oxidized using Jones’ conditions12 to
yield the glucuronic acid 16 that was converted to
Scheme 5. Reagents and conditions: (a) NaOCH3, CH3OH, rt, 86%; (b) CrO3, 3.5 M H2SO4, acetone; (c) CH2N2 in Et2O, CH2Cl2, rt, 64% for two
steps; (d) Ac2O, AcOH, TFA, 60 ꢁC, 67%; (e) hydrazine acetate, DMF, rt, 82%; (c) trichloroacetonitrile, K2CO3, CH2Cl2, rt, 63%.

A. Fekete et al. / Carbohydrate Research 341 (2006) 1312–1321
1315
Scheme 6. Reagents and conditions: (a) NaOCH3, CH3OH, rt, 95%; (b) TEMPO, NaOCl, KBr, NaHCO3; (c) CH3I, DMF, 0 ꢁC to rt, 71% for two
steps; (d) Ac2O, AcOH, TFA, 60 ꢁC, 64%; (e) n-Bu2SnO, CH3OH, 50 ꢁC, 80%; (c) trichloroacetonitrile, K2CO3, CH2Cl2, rt, 82%.
Scheme 7. Reagents and conditions: (a) TMSOTf, CH2Cl2, ꢀ50 ꢁC, 35% for 8 and 26% for 9.
8 showed good agreement with the literature data,2 we
concluded that the natural saccharide had the penulti-
mate sugar unit with Rhap configuration.
raglycosyl alditol obtained from natural sources, there
were three ꢁ1 Hz and one 7.75 Hz coupling constants.
The last of these coupling constants (7.75 Hz) was
assigned to the 3,4-di-O-methyl-b-D-glucuronic acid
moiety. These anomeric proton signals may prove that
the penultimate building block possesses 6-deoxy-L-
manno (and not 6-deoxy-L-talo) configuration.
Therefore, we prepared just one pentasaccharide, 27,
from 8 as the trisaccharide donor and 104 as acceptor
using the NIS/TfOH promoter system6,8 (Scheme 8).
The product was obtained in 30% yield. The NMR data
of this pentasaccharide is provided in Table 2. The
sequence of the deprotection of 27 was the following:
the OPNP-aglycone was converted to p-trifluoroacet-
amidophenyl group one through mild reduction under
hydrogen in the presence of PtO2 and amide-formation,
then the acetyl group was cleaved and finally catalytic
hydrogenation over Pd(OH)2 resulted in the deprotected
pentasaccharide 11 (for the NMR data, see Table 2)
(Scheme 9).
3. Experimental
3.1. General methods
Optical rotations were measured at rt with a Perkin–
Elmer 241 automatic polarimeter in CHCl3. Melting
points were determined on a Kofler apparatus and are
uncorrected. TLC was performed on Kieselgel 60 F254
(Merck) with detection by charring with 50% aqueous sul-
furic acid. Column chromatography was performed on
In conclusion, we have developed a chemical synthesis
of a spacer-armed pentasaccharide hapten of the M.
avium serovar 19. Brennan and co-workers2 have estab-
lished the structure of the tetraglycosyl alditol released
1
Silica Gel 60 (Merck 63–200 mesh). H (200, 360 and
1
from GPL antigen of M. avium serovariant 19. The H
500 MHz) and 13C NMR (50.3, 90.54, 125.76 MHz) spec-
tra were recorded with Bruker WP-200 SY, Bruker AM-
360 and Bruker DRX-500 spectrometers. Internal refer-
NMR data of the synthetic pentasaccharide and that
of the native one showed good agreement. In the ano-
1
1
meric proton signals in the H NMR spectra of the tet-
ences: TMS (0.000 ppm for H), CDCl3 (77.00 ppm for

1316
A. Fekete et al. / Carbohydrate Research 341 (2006) 1312–1321
Table 1. 1H and 13C NMR (CDCl3) data of compounds 8 and 9: dH, dC (ppm), J (Hz)
8
9
d
1H
d
13C
d
1H
d
13C
Rhap
Rhap
1
2
3
4
5
5.31 (J1,2 = 1.5)
3.86 (J2,3 = 3)
3.97 (J3,4 = 9.5)
3.59 (J4,5 = 9.5)
4.06
81.1
80.9
79.6
80.7
1
2
3
4
5
5.34 (J1,2 = 5)
3.86 (J2,3 = 4)
3.97 (J3,4 = 11.5)
3.54 (J4,5 = 11.5)
4.06
81.3
80.5
80.7
80.8
68.7
68.8
CH3
SCH2CH3
1.27 (J5,6 = 6)
1.21, 2.60
18.3
18.5, 25.5
CH3
SCH2CH3
1.25 (J5,6 = 7)
1.27, 2.60
17.5
17.1, 25.7
3-C-Me-Rhap
Talp
1
2
5.00 (J1,2 = 1.5)
3.18
99.8
83.8
1
2
5.07 (J1,2 = 3)
2.96
100.2
83.3
3
—
3
—
4
5
3.22 (J4,5 = 7)
3.65
1.37
84.0
67.7
16.1
15.3
4
5
2.8 (J4,5 = 3.5)
3.91
1.42
84.4
67.4
18.1
15.2
CH3(3)
CH3(6)
CH3(3)
CH3(6)
1.21 (J5,6 = 6)
1.29 (J5,6 = 7)
GlcpA
GlcpA
1
2
3
4
4.76 (J1,2 = 8)
5.02 (J2,3 = 9.5)
3.32 (J3,4 = 9.5)
3.58 (J4,5 = 9.5)
3.76
95.8
72.6
84.5
80.7
74.6
52.4
1
2
3
4
4.76 (J1,2 = 9)
4.99 (J2,3 = 11)
3.32 (J3,4 = 11)
3.61 (J4,5 = 12.5)
3.77
96.0
73.1
84.6
80.8
74.4
52.8
5
5
COOCH3
3.66
COOCH3
3.68
Scheme 8. Reagents and conditions: (a) NIS, TfOH, CH2Cl2, ꢀ30 ꢁC, 30%.
1
13C for organic solutions). Generally, the H and 13C
3.2. 1,2,6-Tri-O-acetyl-3,4-di-O-methyl-D-glucopyranose
(13)
NMR assignments have been established from one-
dimensional NMR spectra. In a few cases, the proton-sig-
nal assignments were supported by analysis of two-
dimensional 1H–1H correlation spectra (COSY) and
selective TOCSY experiments, as well as the carbon-
signal assignments by two-dimensional 13C–1H correla-
tion maps (HETCOR). Elemental analyses were
performed at the analytical laboratories in Debrecen.
Abbreviations: Ac = acetyl, Bn = benzyl, PNP = p-
nitrophenyl, PTFAAP = p-trifluoroacetamidophenyl.
To a solution of 3,4-di-O-methyl-D-glucopyranose 125
(3.94 g, 18.94 mmol) in pyridine (50 mL) was added
Ac2O (20 mL). After stirring for 2 h at rt the mixture
was concentrated. The residue was diluted with CH2Cl2,
extracted with aq 1 M HCl and satd aq NaHCO3 solution,
dried and concentrated. The crude product was purified
by silica column chromatography (7:3, hexane/EtOAc)
to yield 13 (5.48 g, 86%) as a colourless syrup: [a]D

A. Fekete et al. / Carbohydrate Research 341 (2006) 1312–1321
1317
Table 2. 1H and 13C NMR data of compounds 27 and 11: dH, dC (ppm), J (Hz)
27a
11b
1H
d
1H
d
13C
d
d
13C
Talp
Talp
1
2
3
4
5
5.66 (J1,2 = 6) (JC1,H1 = 175.5)
4.24 (J2,3 = 3)
4.60 (J3,4 = 8)
4.25 (J4,5 = 2)
4.03
98.6
71.3
74.9
76.5
67.8
15.8
1
2
3
4
5
5.59 (J1,2 = 1)
4.09 (J2,3 = 3.5)
4.20 (J3,4 = 3.5)
3.73 (J4,5 = 1)
4.17
98.2
77.0
65.8
71.6
68.4
15.6
CH3
PhCH
1.30 (J5,6 = 6.5)
5.81
CH3
1.16 (J5,6 = 6.5)
Rhap
Rhap
1
2
3
4
5.05 (J1,2 = 1.8) (JC1,H1 = 169.5)
3.73 (J2,3 = 3)
4.05 (J3,4 = 9)
3.50 (J4,5 = 9)
3.79
98.9
79.6
79.3
80.5
68.9
18.5
1
2
3
4
5
4.98 (J1,2 = 1)
4.09 (J2,3 = 3)
3.82 (J3,4 = 9.5)
3.48 (J4,5 = 9.5)
3.81
102.6
70.1
78.2
71.5
67.1
17.1
5
CH3(3)
1.18 (J5,6 = 6)
CH3(3)
1.26 (J5,6 = 6.5)
Rhap
Rhap
1
2
3
4
5
CH3
5.03 (J1,2 = 2) (JC1,H1 = 169.5)
3.82 (J2,3 = 3)
3.96 (J3,4 = 9)
3.51 (J4,5 = 9.5)
3.90
1.36 (J5,6 = 6)
95.5
78.4
78.2
80.6
68.8
18.3
1
2
3
4
5.00 (J1,2 = 1)
4.13 (J2,3 = 3)
3.82 (J3,4 = 9.5)
3.53 (J4,5 = 9.5)
3.81
102.8
70.0
78.2
71.3
69.6
17.1
CH3
1.23 (J5,6 = 6.5)
3-C-Me-Rhap
3-C-Me-Rhap
1
2
4.97 (J1,2 = 1.5) (JC1,H1 = 169.5)
3.12
99.9
83.8
1
2
5.05 (J1,2 = 1)
3.53
98.9
83.2
3
—
3
—
4
5
3.17 (J4,5 = 9.5)
3.60
1.36
83.9
67.6
16.0
18.5
4
5
3.78 (J4,5 = 9.5)
3.14
1.41
69.8
84.6
CH3(3)
CH3(6)
CH3(3)
CH3(6)
1.17 (J5,6 = 6)
1.23 (J5,6 = 6.5)
17.1
GlcpA
GlcpA
1
2
3
4
4.72 (J1,2 = 8) (JC1,H1 = 159.5)
5.00 (J2,3 = 10)
3.30 (J3,4 = 10)
3.56 (J4,5 = 10)
3.74
95.7
72.6
84.5
80.6
74.5
52.5
1
2
3
4
4.78 (J1,2 = 7.5)
3.42 (J2,3 = 9.5)
3.35 (J3,4 = 9.5)
3.43 (J4,5 = 9.5)
4.05
96.7
72.6
85.2
80.8
73.2
53.4
5
5
COOCH3
3.73
COOCH3
3.78
a In CDCl3.
b In CD3OD.
+55.0 (c 1.1, CHCl3); 13 (a): 1H NMR (CDCl3): d 6.21 (d,
1H, J1,2 = 3.5 Hz, H-1), 4.90 (dd, 1H, J2,3 = 9.5 Hz, H-2),
(300 mg, 3.24 mmol). After stirring for 4 h at rt the
mixture was diluted with CH2Cl2, extracted with
H2O, dried and concentrated. The crude product was
purified by silica column chromatography (3:2, hex-
ane/EtOAc) to give 14 (480 mg, 92%) as a colourless
syrup: 14 (a): 1H NMR (CDCl3): d 5.35 (d, 1H,
J1,2 = 3.5 Hz, H-1), 4.73 (dd, 1H, J2,3 = 10 Hz, H-2),
4.31 (dd, 1H, J6;6 ¼ 11:5 Hz, H-60), 4.24 (dd, 1H, H-6),
0
0
3.48 (ddd, 1H, J5;6 ¼ 2:5 Hz, J5,6 = 4 Hz, H-5), 3.56,
3.59 (2s, 3-3H, OCH3), 3.50 (s, 1H, OH), 3.25, 3.61 (2
dd, 1-1H, J3,4 = 8.5 Hz, J4.5 = 9.5 Hz, H-3, H-4), 2.07,
2.10, 2.15 (3s, 9H, 3COCH3); 13C NMR (CDCl3): d
168.9, 169.8, 170.6 (3COCH3) 89.5 (C-1), 81.1, 71.2,
71.5, 79.0 (C-2, C-3, C-4, C-5), 62.5 (C-6), 60.8 (·2)
(2OCH3), 20.7, 20.8 (3COCH3). Anal. Calcd for
C14H22O9: C, 50.30; H, 6.63. Found: C, 50.42; H, 6.49.
4.21 (dd, 1H, J6;6 ¼ 12 Hz, H-60), 4.36 (dd, 1H, H-
0
0
6), 4.00 (ddd, 1H, J5;6 ¼ 2 Hz, J5,6 = 4.5 Hz, H-5),
3.59, 3.53 (2s, 3-3H, OCH3), 3.68 (dd, 1H,
J3,4 = 9 Hz, H-3), 3.61 (dd, 1H, J4.5 = 10 Hz, H-4),
2.15, 2.11 (2s, 3-3H, 2COCH3); 13C NMR (CDCl3):
d 170.9, 170.4 (2COCH3) 90.3 (C-1), 79.7, 79.5, 73.3,
68.8 (C-2, C-3, C-4, C-5), 63.0 (C-6), 60.9, 60.7
(2OCH3), 21.0, 20.9 (2COCH3). Anal. Calcd for
C12H20O8: C, 49.31; H, 6.90. Found: C, 49.45; H,
6.82.
3.3. 2,6-Di-O-acetyl-3,4-di-O-methyl-D-glucopyranose
(14)
To a solution of compound 13 (600 mg, 1.79 mmol) in
dry DMF (20 mL) was added hydrazine acetate

1318
A. Fekete et al. / Carbohydrate Research 341 (2006) 1312–1321
2:1 Hz; J5 ;6 b ¼ 6:1 Hz, H-50), 3.31 (dd, 1H, J3 ;4
¼
¼
0
0
0
0
8:9 Hz, H-30), 3.21 (d, 1H, H-2), 3.20 (dd, 1H, J4 ;5
0
0
9:8 Hz, H-40), 3.17 (d, 1H, J4,5 = 9.6 Hz, H-4), 3.32,
3.40, 3.41, 3.50 (4s, 12H, 4OCH3), 2.08, 2.06 (2s, 3-3H,
2COCH3), 1.36 (s, 3H, CH3(3)), 1.28 (d, 3H, J5,6
=
6.2 Hz, H-6); 13C NMR (CDCl3): d 170.6, 169.2
(2COCH3), 99.0 (C-1), 95.5 (C-10), 85.4 (C-30), 84.2 (C-4),
83.7 (C-2), 80.6 (C-3), 79.8 (C-40), 73.3 (C-50), 73.1 (C-20),
67.2 (C-5), 63.4 (C-60), 61.4, 60.7, 59.3, 55.2 (4OCH3),
21.2, 21.0 (COCH3), 18.5 (C-6), 15.8 (CH3(3)). Anal.
Calcd for C22H38O12: C, 53.43; H, 7.74. Found: C,
53.58; H, 7.53.
3.6. Methyl 2,6-di-O-acetyl-3,4-di-O-methyl-a-D-gluco-
pyranosyl-(1!3)-6-deoxy-3-C-methyl-2,4-di-O-methyl-
a-L-talopyranoside (6a) and methyl 2,6-di-O-acetyl-3,4-
di-O-methyl-a-D-glucopyranosyl-(1!3)-6-deoxy-3-C-
methyl-2,4-di-O-methyl-a-L-talopyranoside (6b)
Scheme 9. Reagents and conditions: (a) PtO2, H2, EtOAc; trifluoro-
acetic anhydride, pyridine; NaOCH3, CH3OH; Pd(OH)2, H2, CH3OH,
13% for four steps.
3.4. 2,6-Di-O-acetyl-3,4-di-O-methyl-b-D-glucopyranosyl
trichloroacetimidate (4)
To a solution of the donor 4 (690 mg, 1.58 mmol) and
acceptor 33 (520 mg, 2.37 mmol) in dry CH2Cl2 (5 mL),
TMSOTf (86 lL, 0.45 mmol) was added at ꢀ50 ꢁC. After
20 min. stirring at ꢀ50 ꢁC, Et3N (100 lL) was added. The
mixture was diluted with CH2Cl2 and after extractive
work-up the crude syrup was purified by silica column
chromatography (7:3 ! 1:1, hexane/EtOAc) to give pure
6a (195 mg, 25%) and 6b (265 mg, 34%) both as colourless
syrups: 6a: [a]D +53.9 (c 0.8, CHCl3); 1H NMR (CDCl3):
To a solution of compound 14 (50 mg, 0.17 mmol) in
dry CH2Cl2 (5 mL) were added 0.5 mL trichloroaceto-
nitrile (0.5 mL, 5 mmol) and K2CO3 (400 mg,
5.05 mmol). After stirring for 1 day at rt, the mixture
was diluted with CH2Cl2, filtered and concentrated.
The residue was purified by silica column chromatogra-
phy (9:1, hexane/EtOAc containing 1% Et3N) to give 4
d 5.48 (d, 1H, J1 ;2 ¼ 3:8 Hz, H-10), 4.77 (d, 1H, J1,2
=
0
0
1
7.1 Hz, H-1), 4.63 (dd, 1H, J2 ;3 ¼ 10 Hz, H-20), 4.28
(45 mg, 61%) as a syrup: H NMR (CDCl3): d 8.64 (s,
0
0
(m, 1-1H, H-5, H-60a), 4.19 (m, 1-1H, H-50, H-60b), 3.57
1H, NH), 5.74 (d, 1H, J1,2 = 8 Hz, H-1), 5.17 (dd, 1H,
J2,3 = 8 Hz, H-2), 4.31 (dd, 1H, J6;6 ¼ 11:5 Hz, H-60),
(t, 1H, J3 ;4 ¼ 8:9 Hz, H-30), 3.57, 3.53, 3.50, 3.47, 3.39
0
0
0
(5s, 15H, OCH3), 3.10 (t, 1H, J4 ;5 ¼ 8:9 Hz, H-40), 3.02
(d, 1H, J4,5 = 6 Hz, H-4), 2.69 (d, 1H, H-2), 2.10, 2.09
(2s, 3-3H, COCH3), 1.47 (s, 3H, CH3(3)), 1.44 (d, 3H,
J5,6 = 7 Hz, H-6); 13C NMR (CDCl3): d 170.7, 170.0
(COCH3), 97.7 (C-1), 91.6 (C-10), 84.3 (C-2), 83.0 (C-4),
82.0 (C-30), 80.2 (C-3), 80.0 (C-40), 73.5 (C-20), 69.2 (C-5),
68.2 (C-50), 63.7 (C-60), 61.1, 60.8, 60.6, 59.5, 56.3
(5OCH3), 21.2 (COCH3), 19.0 (CH3(3)), 14.2 (C-6). Com-
pound 6b: [a]D ꢀ24.2 (c 1.1, CHCl3); 1H NMR (CDCl3): d
0
4.37 (dd, 1H, H-6), 3.64 (ddd, 1H, J5;6 ¼ 2 Hz,
0
0
J5,6 = 4.5 Hz, H-5), 3.56, 3.54 (2s, 3-3H, OCH3), 3.36,
3.42 (2 dd, 1-1H, J3,4 = 8 Hz, J4.5 = 8 Hz, H-3, H-4),
2.08, 2.10 (2s, 3-3H, 2COCH3); 13C NMR (CDCl3): d
95.8 (C-1), 84.3, 78.8, 73.6, 71.5 (C-2, C-3, C-4, C-5),
62.6 (C-6), 60.6, 60.4 (2OCH3), 20.8 (2COCH3).
3.5. Methyl 2,6-di-O-acetyl-3,4-di-O-methyl-b-D-gluco-
pyranosyl-(1!3)-3-C-methyl-2,4-di-O-methyl-a-L-
rhamnopyranoside (5)
4.91 (dd, 1H, J2 ;3 ¼ 9:2 Hz, H-20), 4.75 (d, 1H, J1 ;2
¼
0
0
0
0
7:8 Hz, H-10), 4.69 (d, 1H, J1,2 = 4.1 Hz, H-1), 4.33 (dd,
1H, J6 a;6 b ¼ 11:7 Hz, H-60a), 4.18 (dd, 1H, H-60b), 4.04
The solution of the donor 4 (560 mg, 1.38 mmol) and
acceptor 23 (180 mg, 0.8 mmol) in dry CH2Cl2 (4 mL)
was cooled to ꢀ50 ꢁC, then TMSOTf (78 lL, 0.41 mmol)
was added dropwise. After stirring for 30 min, Et3N
(100 lL) was added. The mixture was diluted with
CH2Cl2, extracted with H2O, dried and concentrated.
The crude product was purified by column chromatogra-
phy (95:5, CH2Cl2/acetone) to yield 5 (165 mg, 42%) as a
0
0
0
0
0
0
(br m, 1H, H-5), 3.40 (ddd, 1H, J5 ;6 a ¼ 2:3 Hz, J5 ;6 b
¼
6:5 Hz, H-50), 3.29 (t, 1H, J3 ;4 ¼ 8:8 Hz, H-30), 3.19
0
0
(dd, 1H, J4 ;5 ¼ 9:8 Hz, H-40), 2.90 (d, 1H, J4,5
=
0
0
3.5 Hz, H-4), 2.83 (d, 1H, H-2), 3.49, 3.41, 3.40, 3.35
(4s, 15H, OCH3), 2.06, 2.04 (2s, 3-3H, COCH3), 1.38 (s,
3H, CH3(3)), 1.26 (d, 3H, J5,6 = 6.8 Hz, H-6); 13C NMR
(CDCl3): d 170.6, 169.4 (COCH3), 99.3 (C-1), 95.8
(C-10), 85.4 (C-30), 83.9 (C-4), 83.5 (C-2), 80.1 (C-40),
79.2 (C-3), 73.3 (C-20), 73.1 (C-50), 67.6 (C-5), 63.7
(C-60), 60.4, 61.0, 59.9, 55.8 (OCH3), 21.2, 20.8 (COCH3),
20.4 (CH3(3)), 16.0 (C-6). Anal. Calcd for C22H38O12: C,
53.43; H, 7.74. Found: C, 53.40; H, 7.83.
1
colourless syrup: [a]D ꢀ25.45 (c 0.3, CHCl3); H NMR
(CDCl3): d 4.98 (dd, 1H, J2 ;3 ¼ 9:6 Hz, H-20), 4.75 (d,
0
0
1H, J1 ;2 ¼ 8 Hz, H-10), 4.6 (d, 1H, J1,2 = 1.8 Hz, H-1),
0
0
4.37 (dd, 1H, J6 a;6 b ¼ 11:8 Hz, H-60a), 4.22 (dd, 1H, H-
0
0
60b), 3.54 (br m, 1H, H-5), 3.42 (ddd, 1H, J5 ;6 a
¼
0
0

A. Fekete et al. / Carbohydrate Research 341 (2006) 1312–1321
1319
3.7. Methyl 2-O-acetyl-3,4-di-O-methyl-b-D-glucopyr-
anosyl-(1!3)-3-C-methyl-2,4-di-O-methyl-a-L-rhamno-
pyranoside (15)
3.9. [Methyl (2-O-acetyl-3,4-di-O-methyl-b-D-glucopyran-
uronyl)uronate]-(1!3)-1-O-acetyl-3-C-methyl-2,4-di-O-
methyl-L-rhamnopyranose (18)
To a solution of compound 5 (160 mg, 0.32 mmol) in
CH3OH (10 mL), 1 M NaOCH3 in CH3OH (60 lL,
0.06 mmol) was added. After stirring at rt for 8 h, the
mixture was neutralized with Amberlite IR 120 (H+)
resin, filtered and the filtrate was concentrated. The
crude product was purified by column chromatography
(9:1, CH2Cl2/acetone) to afford 15 (125 mg, 86%) as a
To a solution of compound 17 (70 mg, 0.14 mmol) in
Ac2O (1 mL) and AcOH (1 mL), TFA (50 lL,
0.65 mmol) was added. After stirring for 1 day at
60 ꢁC the mixture was concentrated, the crude product
was purified by column chromatography (85:15,
CH2Cl2/EtOAc) to yield 17 (48 mg, 67%) as a syrup:
1
[a]D ꢀ53.8 (c 1.0, CHCl3); H NMR (CDCl3): d 6.05
1
0
0
colourless syrup: [a]D ꢀ32.4 (c 1.0, CHCl3); H NMR
(d, 1H, J1,2 = 2 Hz, H-1), 5.04 (dd, 1H, J2 ;3 ¼ 9:5 Hz,
(CDCl3): d 4.96 (t, 1H, J2 ;3 ¼ 8 Hz, H-20), 4.82 (d,
H-20), 4.8 (d, 1H, J1 ;2 ¼ 7:5 Hz, H-10), 3.78 (s, 3H,
COOCH3), 3.54, 3.53, 3.4, 3.36 (4s, 12H, 4OCH3),
3.33 (d, 1H, J4,5 = 9.5 Hz, H-4), 3.22 (d, 1H, H-2),
2.10, 2.09 (2s, 3-3H, 2COCH3), 1.39 (s, 3H, CH3(3)),
1.29 (d, 1H, J5,6 = 6 Hz, H-6); 13C NMR (CDCl3): d
169.1, 169.1 (2COCH3), 168.3 (COOCH3), 90.9 (C-1),
95.6 (C-10), 84.3, 83.2, 82.1, 80.3, 74.4, 72.4, 69.5 (C-
30, C-4, C-2, C-4, C-50, C-20, C-5), 80.2 (C-3), 61.3,
60.5, 60.3, 58.7 (4OCH3), 52.4 (COOCH3), 21.3
(2COCH3), 18.2 (C-6), 15.9 (CH3(3)). Anal. Calcd for
C22H36O13: C, 51.96; H, 7.14. Found: C, 51.86; H, 7.19.
0
0
0 0
1H, J1 ;2 ¼ 8 Hz, H-10), 4.67 (d, 1H, J1,2 = 2 Hz, H-
0
0
0
0
0
0
1), 3.87 (dd, 1H, J5 ;6 a ¼ 2 Hz, J6 a;6 b ¼ 12 Hz, H-
60a), 3.76 (dd, 1H, J5 ;6 b ¼ 3 Hz, H-60b), 3.57, 3.53,
3.44, 3.35 (4s, 15H, 5OCH3), 3.19 (d, 1H, J1,2 = 2 Hz,
H-2), 3.16 (d, 1H, J4,5 = 9.5 Hz, H-4), 2.11 (s, 3H,
COCH3), 1.37 (s, 3H, CH3(3)), 1.29 (d, 3H,
0
0
J5,6 = 6 Hz, H-6); 13C NMR (CDCl3):
d
169.3
(COCH3), 98.3 (C-1), 95.0 (C-10), 87.8, 84.2, 83.0,
78.8, 75.6, 72.9, 67.1 (C-30, C-4, C-2, C-4, C-50, C-20,
C-5), 80.9 (C-3), 61.9 (C-60), 61.2, 60.4, 60.0, 58.8,
55.03 (5OCH3), 21.0 (COCH3), 18.2 (C-6), 16.4
(CH3(3)). Anal. Calcd for C20H36O11: C, 53.09; H,
8.02. Found: C, 53.17; H, 8.13.
3.10. [Methyl (2-O-acetyl-3,4-di-O-methyl-b-D-glucopy-
ranuronyl)uronate]-(1!3)-3-C-methyl-2,4-di-O-methyl-
L-rhamnopyranose (19)
3.8. Methyl [methyl (2-O-acetyl-3,4-di-O-methyl-b-D-
glucopyranosyl)uronate]-(1!3)-3-C-methyl-2,4-di-O-
methyl-a-L-rhamnopyranoside (17)
To a solution of compound 18 (60 mg, 0.12 mmol) in
dry DMF (2 mL), hydrazine acetate (32 mg, 0.35 mmol)
was added. After stirring for 1 day at rt the mixture was
diluted with CH2Cl2, extracted with H2O, dried and
concentrated. The residue was purified by column chro-
matography (1:1, hexane/EtOAc) to give 19 (46 mg,
To a solution of 15 (70 mg, 0.15 mmol) in acetone
(3 mL), CrO3 (170 mg, 1.7 mmol dissolved in 500 lL
of 3.5 M H2SO4) was added. After stirring for 1 h at
rt, the mixture was poured onto ice-cold H2O and
extracted with CH2Cl2. The organic layer was washed
with H2O and concentrated. The crude product (16)
was dissolved in CH2Cl2 (5 mL) and a solution of
CH2N2 in Et2O was added dropwise until TLC analysis
showed complete conversion. The mixture was concen-
trated and the residue was purified by column chroma-
tography (7:3, hexane/EtOAc) to give 17 (46 mg, 64%)
as a syrup: [a]D ꢀ50.7 (c 1.0, CHCl3); 1H NMR
1
82%) as a syrup: [a]D ꢀ19.9 (c 0.7, CHCl3); H NMR
(CDCl3): d 5.18 (d, 1H, J1,2 = 2 Hz, H-1), 4.99 (dd,
1H, J2 ;3 ¼ 9 Hz, H-20), 4.82 (d, 1H, J1 ;2 ¼ 8 Hz, H-
10), 4.75 (s, 1H, OH) 3.81 (s, 3H, COOCH3), 3.65,
3.54, 3.5, 3.45 (4s, 12H, OCH3), 2.1 (s, 3H, COCH3),
1.32 (s, 3H, CH3(3)), 1.3 (d, 1H, J5,6 = 6 Hz, H-6); 13C
NMR: d 169.0 (COCH3), 168.5 (COOCH3), 92.2 (C-1),
96,2 (C-10), 85.7, 84.5, 84.3, 80.7, 73.9, 72.5, 70.4 (C-
30, C-4, C-2, C-4, C-50, C-20, C-5), 81.9 (C-3), 62.7,
60.8, 60.4, 58.8, (4OCH3), 52.6 (COOCH3), 20.9
(COCH3), 18.5 (C-6), 14.1 (CH3(3)). Anal. Calcd for
C20H34O12: C, 51.50; H, 7.35. Found: C, 51.56; H, 7.29.
0
0
0
0
0
0
0
0
(CDCl3): d 5.03 (dd, 1H, J1 ;2 ¼ 8 Hz; J2 ;3 ¼ 9:5 Hz,
H-20), 4.8 (d, 1H, J1 ;2 ¼ 8 Hz, H-10), 4.62 (d, 1H,
0
0
J1,2 = 2 Hz, H-1), 3.78 (s, 3H, COOCH3), 3.54, 3.51,
3.42, 3.36, 3.34 (5s, 15H, OCH3), 3.19 (d, 1H, J4,5
=
9.5 Hz, H-4), 3.18 (d, 1H, H-2), 2.10 (s, 3H, COCH3),
1.36 (s, 3H, CH3(3)), 1.28 (d, 1H, J5,6 = 6 Hz, H-6);
3.11. Methyl 3,4-di-O-methyl-b-D-glucopyranosyl-(1!3)-
6-deoxy-3-C-methyl-2,4-di-O-methyl-a-L-talopyranoside
(21)
13C NMR (CDCl3):
d
169.1 (COCH3), 168.4
(COOCH3), 98.4 (C-1), 95.6 (C-10), 84.3, 83.8, 83.1,
80.3, 74.3, 72.4, 67.0 (C-30, C-4, C-2, C-4, C-50, C-20,
C-5), 81.0 (C-3), 61.2, 60.41, 60.2, 58.6, 55.0 (OCH3),
52.4 (COOCH3), 20.9 (COCH3), 18.1 (C-6), 15.9
(CH3(3)). Anal. Calcd for C21H38O12: C, 52.27; H,
7.94. Found: C, 52.34; H, 7.85.
To a solution of compound 6b (48 mg, 0.1 mmol) in
CH3OH (3 mL), 2 M NaOCH3 in CH3OH (10 lL) was
added. After stirring for 3 h at rt the mixture was neu-
tralized with Amberlite IR 120 (H+), filtered, concen-
trated and the residue was purified by silica column

1320
A. Fekete et al. / Carbohydrate Research 341 (2006) 1312–1321
chromatography (6:4, CH2Cl2/acetone) to yield pure 21
(39 mg, 95%) as a colourless syrup. [a]D ꢀ43.0 (c 0.13,
J5,6 = 6.5 Hz, H-6); 13C NMR (CDCl3): d 169.2, 168.8
(2COCH3), 168.6 (COOCH3), 96.0 (C-1), 91.2 (C-10),
84.4, 83.2, 82.3, 80.3, 74.1, 72.6, 69.7 (C-30, C-4, C-2,
C-40, C-20, C-50, C-5), 78.9 (C-3), 61.0, 60.5, 60.3, 59.8,
(4OCH3), 52.4 (COOCH3), 21.2, 20.96 (2COCH3), 20.6
(C-6), 15.5 (CH3(3)). Anal. Calcd for C22H36O13: C,
51.96; H, 7.14. Found: C, 51.78; H, 7.23.
1
CHCl3); H NMR (CDCl3): d 4.84 (br s, 1H, OH-20),
0
0
4.78 (d, 1H, J1,2 = 6 Hz, H-1), 4.54 (d, 1H, J1 ;2
¼
7:5 Hz, H-10), 4.25 (br m, 1H, J4,5 = 4.5 Hz, H-5),
3.67, 3.54, 3.52, 3.49, 3.45 (5s, 15H, OCH3), 3.20 (br s,
1H, OH-60), 2.81 (d, 1H, H-2), 1.49 (s, 3H, CH3(3)),
1.40 (d, 3H, J5,6 = 7 Hz, H-6). Anal. Calcd for
C18H34O10: C, 52.67; H, 8.35. Found: C, 52.49; H, 8.52.
3.14. [Methyl (2-O-acetyl-3,4-di-O-methyl-b-D-glucopyr-
anosyl)uronate]-(1!3)-6-deoxy-3-C-methyl-2,4-di-O-
methyl-a-L-talopyranose (25)
3.12. Methyl [methyl (3,4-di-O-methyl-b-D-glucopyran-
osyl)uronate]-(1!3)-6-deoxy-3-C-methyl-2,4-di-O-methyl-
a-L-talopyranoside (23)
To a solution of the compound 24 (22 mg, 0.043 mmol)
in CH3OH (0.5 mL), n-Bu2SnO (5.4 mg, 0.021 mmol)
was added. After stirring for 4 h at 50 ꢁC the mixture
was concentrated. The residue was purified by silica col-
umn chromatography (8:2, CH2Cl2/acetone, 1% Et3N)
Compound 21 (48 mg, 0.11 mmol) was suspended in
satd aq NaHCO3 (2 mL), KBr (1 mg, 0.008 mmol) and
2,2,6,6-tetramethylpiperidine-1-oxyl (2 mg, 0.013 mmol)
were added and the mixture was cooled to 0 ꢁC, then
NaOCl (1 mL) was added dropwise. The resulting mix-
ture was stirred for 1 day at rt and then concentrated.
To the solid residue 22 were added anhydrous DMF
(4 mL) and CH3I (10 lL) at 0 ꢁC. After stirring for
1 day at rt, the mixture was concentrated, diluted with
CH2CH2, extracted with H2O, dried and concentrated.
The resulting syrup was purified by silica column chro-
matography (8:2, CH2Cl2/acetone) to afford 23 (30 mg,
71%) as a colourless syrup: [a]D ꢀ64.5 (c 0.3, CHCl3);
1H NMR (CDCl3): d 4.74 (br s, 1H, OH-20), 4.48 (d,
1
to give 25 (16 mg, 80%) as a syrup. H NMR (CDCl3):
d 5.02 (dd, 1H, J2 ;3 ¼ 9 Hz, H-20), 4.90 (d, 1H,
0
0
J1 ;2 ¼ 8 Hz, H-10), 5.15 (d, 1H, J1,2 = 3 Hz, H-1), 3.80
(s, 3H, COOCH3), 3.58, 3.55, 3.47, 3.41 (4s, 12H,
4OCH3), 2.12 (s, 3H, COCH3), 1.26 (s, 3H, CH3(3)),
1.40 (d, 1H, J5,6 6.5 Hz, H-6).
0
0
3.15. Ethyl [methyl (2-O-acetyl-3,4-di-O-methyl-b-D-
glucopyranosyl)uronate]-(1!3)-3-C-methyl-2,4-di-O-
methyl-a-L-rhamnopyranosyl-(1!3)-2,4-di-O-benzyl-1-
thio-a-L-rhamnopyranoside (8)
1H, J1 ;2 ¼ 8 Hz, H-10), 4.69 (d, 1H, J1,2 = 4.5 Hz, H-
1), 4.06 (br m, 1H, H-5), 3.73, 3.59, 3.44, 3.44, 3.43,
3.33 (6s, 18H, OCH3), 3.07 (d, 1H, J4,5 = 4 Hz, H-4),
2.80 (d, 1H, H-2), 1.41 (s, 3H, CH3(3)), 1.32 (d, 3H,
0
0
To a solution of compound 19 (50 mg, 0.11 mmol) in
dry CH2Cl2 (5 mL), trichloroacetonitrile (314 lL,
1.5 mmol) and K2CO3 (500 mg, 5.05 mmol) were added.
After stirring for 1 day at rt the mixture was diluted with
CH2Cl2, filtered and concentrated to afford 20 (42 mg,
63%) as a syrup, which was used in the next step without
purification. The solution of the crude product 20
(42 mg, 0.07 mmol) and acceptor 74 (46.5 mg, 0.12
mmol) in dry CH2Cl2 (500 lL) was cooled to ꢀ50 ꢁC,
then TMSOTf (3.5 lL, 0.018 mmol) was added drop-
wise and the mixture was stirred for 30 min. Et3N
(50 lL) was added, the mixture was diluted with
CH2Cl2, extracted with H2O, dried and concentrated.
The resulting syrup was purified by silica column chro-
matography (7:3, hexane/EtOAc) to yield 8 (20 mg,
35%) as a syrup: [a]D ꢀ67.4 (c 1.1, CHCl3); 1H and
13C NMR data are collected in Table 1. MALDIMS
m/z calcd for C42H60O15S1: 836.36 [M]. Found: 859.41
[M+Na]+.
J5,6 = 6.5 Hz, H-6); 13C NMR (CDCl3):
d 168.8
(COOCH3), 99.2 (C-1), 97.8 (C-10), 86.1, 83.0, 80.4,
74.4, 74.3, 67.2 (C-30, C-4, C-2, C-40, C-20, C-50 and
C-5), 79.9 (C-3), 61.0, 60.5, 60.4, 55.6 (5OCH3), 52.4
(COOCH3), 21.0 (CH3(3)), 15.9 (C-6). Anal. Calcd for
C19H34O11: C, 52.05; H, 7.82. Found: C, 52.17; H, 7.52.
3.13. [Methyl (2-O-acetyl-3,4-di-O-methyl-b-D-glucopyr-
anosyl)uronate]-(1!3)-1-O-acetyl-6-deoxy-3-C-methyl-
2,4-di-O-methyl-a-L-talopyranose (24)
To a solution of the compound 23 (50 mg, 0.11 mmol) in
Ac2O (1 mL) and AcOH (1 mL), TFA (85 lL,
1.1 mmol) was added and the mixture was stirred for
1 day at 60 ꢁC. The mixture was concentrated, the resi-
due was purified by silica column chromatography
(9:1, CH2Cl2/acetone) to yield 24 (36 mg, 64%) as a col-
ourless syrup: [a]D +40.0 (c 0.1, CHCl3); 1H NMR
3.16. Ethyl [methyl (2-O-acetyl-3,4-di-O-methyl-b-D-
glucopyranosyl)uronate]-(1!3)-6-deoxy-3-C-methyl-2,4-
di-O-methyl-a-L-talopyranosyl-(1!3)-2,4-di-O-benzyl-1-
thio-a-L-rhamnopyranoside (9)
(CDCl3): d 4.97 (dd, 1H, J2 ;3 ¼ 9 Hz, H-20), 4.89 (d,
0
0
1H, J1 ;2 ¼ 7:5 Hz, H-10), 6.14 (d, 1H, J1,2 = 2 Hz, H-
1), 4.18 (br m, 1H, H-5), 3.79 (s, 3H, COOCH3), 3.52,
3.51, 3.45, 3.44 (4s, 12H, 3OCH3), 2.99 (d, 1H,
J4,5 = 3.5 Hz, H-4), 2.96 (d, 1H, H-2), 2.10, 2.08 (2s, 3-
3H, 2COCH3), 1.44 (s, 3H, CH3(3)), 1.34 (d, 1H,
0
0
To a solution of the compound 25 (30 mg, 0.06 mmol)
in dry CH2Cl2 (5 mL), trichloroacetonitrile (1 mL,

A. Fekete et al. / Carbohydrate Research 341 (2006) 1312–1321
1321
4.8 mmol) and K2CO3 (500 mg, 5.05 mmol) were added
and the mixture was stirred for 1 day at rt. The mixture
was diluted with CH2Cl2, filtered and concentrated to
afford 26 (32 mg, 82%) as a syrup. The solution of the
crude product 26 (40 mg, 0.07 mmol) and acceptor 74
(60 mg, 0.15 mmol) in dry CH2Cl2 (200 lL) was cooled
to ꢀ50 ꢁC, then TMSOTf (3.5 lL, 0.018 mmol) was
added dropwise and the mixture was stirred for
30 min. Et3N (50 lL) was added. The mixture was di-
luted with CH2Cl2, extracted with H2O, dried and con-
centrated. The residue was purified by silica column
(7 mg) was dissolved in dry CH3OH (2 mL) and stirred
with 0.1 M NaOCH3 in CH3OH (10 lL) for 1 day at
rt. The mixture was then neutralized with Amberlite
IR 120(H+), filtered and concentrated. The crude syrup
was purified by silica column chromatography (6:4,
CH2Cl2/EtOAc) to give 5 mg of the deacetylated conge-
ner. The colourless syrup was dissolved in dry CH3OH,
Pd(OH)2 was added and the mixture was stirred for
1 day at rt. The mixture was filtered and concentrated.
The crude syrup was purified on HPLC (SUPELCOSIL
SPLC-Si, 254 nm, 85:15, EtOAc/hexane) to yield 11
(1.2 mg, 13%) as a colourless syrup: [a]D ꢀ50.2 (c 0.1,
chromatography (6:4, hexane/EtOAc) to yield
9
1
(15 mg, 26%) as a colourless syrup: [a]D ꢀ47.3 (c 0.3).
1H and 13C NMR data are collected in Table 1. MALD-
IMS calcd for C42H60O15S1: 836.36 [M]. Found: 860.47
[M+Na]+.
H2O); H and 13C NMR data are collected in Table 2.
MALDIMS m/z calcd for C44H66F3N1O24: 1049.39
[M]. Found: 1072.93 [M+Na]+.
3.17. p-Nitrophenyl [methyl (2-O-acetyl-3,4-di-O-methyl-
b-D-glucopyranosyl)uronate]-(1!3)-3-C-methyl-2,4-di-O-
methyl-a-L-rhamnopyranosyl-(1!3)-2,4-di-O-benzyl-a-L-
rhamnopyranosyl-(1!3)-2,4-di-O-benzyl-a-L-rhamnopyr-
anosyl-(1!2)-6-deoxy-3,4-O-benzylidene-a-L-talopyr-
anoside (27)
Acknowledgements
The Hungarian Science Fund supported the work of I.
Bajza (OTKA T 035128), A. Liptak (OTKA T
´
´
048798), K. E. Ko¨ver (OTKA T 048713) and the Minis-
´
try of Education (PAL 48/2005) supported that of A.
´
Liptak.
The solution of donor 8 (25 mg, 0.03 mmol) and accep-
tor 104 (42 mg, 0.06 mmol) in dry CH2Cl2 (400 lL) was
cooled to ꢀ30 ꢁC, then solution of NIS (8.2 mg,
0.036 mmol) and TfOH (1 lL, 0.004 mmol) in CH2Cl2
(200 lL) was added dropwise and the mixture was stir-
red for 30 min. Et3N (50 lL) was added, the mixture
was diluted with CH2Cl2, extracted with aqueous 10%
Na2S2O3 and H2O, then dried and concentrated. The
resulting syrup was purified using HPLC to give 27
(13 mg, 30%) as a colourless syrup: [a]D ꢀ70.7 (c 0.1,
References
´
´
1. (a) Liptak, A.; Borbas, A.; Bajza, I. Med. Res. Rev. 1994,
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3. Gyergyoi, K.; Toth, A.; Bajza, I.; Liptak, A. Synlett 1998,
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CHCl3); H and 13C NMR data are collected in Table
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3.18. p-Trifluoroacetamidophenyl [methyl (3,4-di-O-
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2,4-di-O-methyl-a-L-rhamnopyranosyl-(1!3)-a-L-
rhamnopyranosyl-(1!3)-a-L-rhamnopyranosyl-(1!2)-6-
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To a solution of compound 27 (13 mg, 0.009 mmol) in
EtOAc (2 mL), PtO2 (10 mg) was added. After stirring
for 2 h under H2 at rt, the mixture was cooled to 0 ꢁC,
then pyridine (100 lL) and trifluoroacetic anhydride
(50 lL, 0.36 mmol) were added. The mixture was stirred
for 1 h then filtered and concentrated. The residue was
purified by silica column chromatography (8:2,
CH2Cl2/EtOAc) to yield the corresponding trifluoro-
acetamidophenyl derivative. The colourless syrup
´
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41; (b) Szurmai, Z.; Liptak, A.; Snatzke, G. Carbohydr.
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13. de Noy, A. E. J.; Besemer, A. C.; van Bekkum, H.
Synthesis 1996, 1153–1175.
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