Synthesis of a D-rhamnose branched tetrasaccharide, repeating unit of the O-chain from Pseudomonas syringae pv. Syringae (cerasi) 435

Article abstract of DOI:10.1016/j.carres.2004.06.010

The first synthesis of a D-rhamnose branched tetrasaccharide, corresponding to the repeating unit of the O-chain from Pseudomonas syringae pv. cerasi 435, as methyl glycoside is reported. The approach used is based on the synthesis of an opportune buildin

Full text of DOI:10.1016/j.carres.2004.06.010

Carbohydrate
RESEARCH
Carbohydrate Research 339 (2004) 1907–1915
Synthesis of a
of the O-chain from Pseudomonas syringae pv. Syringae (cerasi) 435
D
-rhamnose branched tetrasaccharide, repeating unit
Emiliano Bedini,* Antonella Carabellese, Maria Michela Corsaro, Cristina De Castro
and Michelangelo Parrilli
Dipartimento di Chimica Organica e Biochimica, Universitꢀa di Napoli ‘Federico II’, Complesso Universitario Monte Santangelo,
Via Cintia 4, 80126 Napoli, Italy
Received 3 May 2004; received in revised form 26 May 2004; accepted 13 June 2004
Abstract—The first synthesis of a
Pseudomonas syringae pv. cerasi 435, as methyl glycoside is reported. The approach used is based on the synthesis of an opportune
building-block, that is the methyl 3-O-allyl-4-O-benzoyl-a- -rhamnopyranoside, which was then converted into both a glycosyl
D-rhamnose branched tetrasaccharide, corresponding to the repeating unit of the O-chain from
D
acceptor and two different protected glycosyl trichloroacetimidate donors. Successive couplings of these three compounds afforded
the target oligosaccharide. The reported synthesis is also useful to perform the oligomerization of the repeating unit.
ꢀ 2004 Elsevier Ltd. All rights reserved.
Keywords: O-Chain; Pseudomonas cerasi; Repeating unit;
D-Rhamnose; Oligosaccharide; Synthesis
1. Introduction
bearing, as branches, single monosaccharides, that are
usually from a very small group, comprising - and
Xylp, - and -Rhap, -GlcpNAc, -Fucf and an
unusual sugar, 3-acetamido-3,6-dideoxy- -galactopyra-
nose ( -Fucp3NAc). In particular, the O-chain from
L
D-
Little is known about the effects of bacterial LPS1–3 on
plant cells. The only extensive study is on the ability of
LPS to prevent the hypersensitive response (HR) caused
in plants by avirulent bacteria,4;5 but almost nothing is
known about the molecular basis of the LPS-plant rec-
ognition that leads to this and, eventually, other un-
known interactions.6 Due to its extension out from the
bacterial cell, the O-chain should be highly involved in
recognition mechanism.5 In order to investigate its role,
the availability of O-chain repeating unit oligosaccha-
rides is necessary. In particular any synthesis should be
directed towards oligosaccharides, which may be oligo-
merized, in order to investigate also the influence of the
O-chain length on the biological activity.
L
D
D
D
D
D
Pseudomonas syringae pv. cerasi 435, a general phyto-
pathogenic agent,8 shows the following
D
-rhamnose
branched tetrasaccharide repeating unit 1:9
α-
D
-Rhap
1
↓
3
←
←
←
3)-α-
D
-Rhap-(1 3)-α-
D
-Rhap-(1 2)-α-
1
D
-Rhap-(1
Whereas various
to the O-chains of phytopathogenic bacteria have been
recently synthesized,10–17 few synthesis of
-rhamnose
L-rhamnan oligosaccharides related
D
A recent review7 showed that the O-chains from
phytopathogenic bacteria are typically made of repeat-
ing units with an L- and/or D-rhamnose backbone,
oligosaccharides have been hitherto reported.18–21
In this paper the first synthesis of the tetrasaccharide
unit 1 as methyl glycoside is described. It is noteworthy
that the synthetic approach used aims at the synthesis
of a tetrasaccharide building-block, whose protecting
group pattern could allow its smooth oligomerization to
obtain higher oligosaccharides.
* Corresponding author. Tel.: +39-081-674146; fax: +39-081-674393;
e-mail: ebedini@unina.it
0008-6215/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2004.06.010

1908
E. Bedini et al. / Carbohydrate Research 339 (2004) 1907–1915
2. Results and discussion
N,N0-diisopropylcarbodiimide (DIPC) and 4-dimeth-
ylaminopyridine (DMAP) (79%), afforded acceptor 6 in
good yield (78%) when de-O-allylated with PdCl2.
On the other hand the sequence of two reactions
(acetolysis and cleavage of anomeric acetate) converted
4 into the hemiacetal 7 with 59% yield over two steps. It
is noteworthy that the condition used for the acetolysis
(100:40:1 v/v/v Ac2O/AcOH/H2SO4)25 did not affect the
allyl group. Hemiacetal 7 was then activated as tri-
chloroacetimidate glycosyl donor by treatment with
Cl3CCN and DBU, affording 8 in 72% yield. Subsequent
coupling of donor 8 with acceptor 6 was smoothly per-
formed at )50 ꢁC using BF3ÆOEt2 as acid catalyst:
disaccharide 9 was obtained with 86% yield (Scheme 2).
The a-configuration of the glycosidic bond was ascer-
Since 1 consists of a single monosaccharide type, that is
-rhamnose, an efficient synthetic strategy was based on
the choice of a convenient -rhamnose building-block,
which would be easily converted into both a glycosyl
donor and 2-O- and 3-O-glycosyl acceptors. The chosen
precursor was the alcohol 4, bearing a methoxy group at
the anomeric position, a benzoyl group on O-4 and a
selectively removable allyl protecting group at O-3
position (Scheme 1). Building-block 4 was synthesized
D
D
from the known methyl 2,3-O-isopropylidene-a-D-
rhamnopyranoside 222 by benzoylation and ketal
cleavage to afford 3 (77%), and subsequent dibutyl-
stannylidene mediated allylation of position O-3; the
very good yield of 4 (88%) confirmed the excellent regio-
selectivity of this alkylation method.23
1
tained by measuring the heteronuclear JC;H coupling
constant value (JCꢀ1;Hꢀ1 ¼ 173 Hz) in a coupled HMQC-
From compound 4 two routes had to be developed,
respectively, towards a glycosyl donor and a glycosyl
acceptor respectively. In particular 4 could be used
directly as 2-O-glycosyl acceptor, nevertheless this
compound was discarded since an oligomerizable tet-
rasaccharide building-block could be not easily obtained
by such a strategy. Thus, it was decided to convert 4 into
a 3-O-glycosyl acceptor, bearing a selective removable
protecting group on O-2 position. The first attempt was
to chloroacetylate this position, but subsequent palla-
dium-catalyzed de-O-allylation caused almost total
migration of the chloroacetyl group from O-2 to O-3.
Better results were achieved by using a levulinoyl (Lev)
protecting group, which is well-known to be less prone
to acyl migration.24 Actually, compound 5, obtained
from 4 by treatment with LevOH in the presence of
COSY experiment.26
The building of the target tetrasaccharide would have
required at this point the conversion of 9 into a glycosyl
acceptor by mere selective removal of the Lev group, but
the two-steps conversion of the allyl into an acetyl group
was at this point included in the synthetic strategy, in
order to ensure a different protection on the 3-O-posi-
tions of residue B and D at tetrasaccharide level and to
allow its future oligomerization. Thus, 9 was firstly
subjected to de-O-allylation and acetylation, then,
without any intermediate chromatographic purification,
the Lev group cleavage was achieved by treatment with
hydrazinium acetate in 4:1 CH2Cl2/MeOH, affording 10
in excellent yield (87% over three-steps). It is noteworthy
that palladium-catalyzed de-O-allylation of 9 produced,
as determined by TLC, a mixture of two compounds,
OH
OR'
O
O
O
O
a
b
BzO
BzO
HO
HO
RO
O
OMe
OMe
OMe
2
3
4: R=All, R'=H
c
5: R=All, R'=Lev
d
6: R=H, R'=Lev
OR
OR
O
O
BzO
AllO
g
BzO
e
7
4
AllO
f
11
OH
O
CCl3
7: R=Ac
8: R=Ac
12: R=Bz
NH
11: R=Bz
Scheme 1. Reagents and conditions: (a) (i) BzCl, pyridine, 0 ꢁC, 60 min; (ii) 4:1 TFA/H2O, rt, 20 min; 77%; (b) (i) Bu2SnO, 10:1 benzene/MeOH 0 ꢁC,
90 min; (ii) Bu4NBr, AllBr, toluene, 65 ꢁC, 2 h; 88%; (c) LevOH, DIPC, DMAP, CH2Cl2, rt, 60 min, 79%; (d) PdCl2, 3:2 MeOH/CH2Cl2, rt,
overnight, 78%; (e) (i) 100:40:1 Ac2O/AcOH/H2SO4, rt, 30 min; (ii) hydrazine acetate, DMF, rt, 40 min; 59% (a=b ¼ 3:5=1); (f) (i) BzCl, pyridine, rt,
30 min; (ii) 100:40:1 Ac2O/AcOH/H2SO4, rt, 60 min; (iii) hydrazine acetate, DMF, rt, 45 min; 58% (a=b ¼ 5 : 1); (g) Cl3CCN, DBU, CH2Cl2, 0 ꢁC,
60 min; 72% for 8, 55% for 12.

E. Bedini et al. / Carbohydrate Research 339 (2004) 1907–1915
1909
OBz
O
BzO
RO
O
C
OAc
OAc
O
BzO
AcO
BzO
B
RO
O
OR'
O
O
a
12, c
BzO
O
BzO
O
A
6 +
8
OMe
OMe
13: R=All
14: R=H
9: R=All, R'=Lev
10: R=Ac, R'=H
d
b
12, e
OBz
OH
O
O
BzO
AllO
HO
D
HO
OBz
OH
O
O
BzO
HO
C
O
O
OAc
O
OH
f
O
BzO
AcO
HO
B
HO
O
O
O
O
BzO
O
HO
O
A
16
OMe
15
OMe
ꢂ
Scheme 2. Reagents and conditions: (a) BF3ÆOEt2, 4 A HW-300 MS, CH2Cl2, )50 ꢁC, 150 min; 86%; (b) (i) PdCl2, 2:1 MeOH/CH2Cl2, rt, 4 h; (ii)
ꢂ
Ac2O, pyridine, rt, overnight; (iii) hydrazine acetate, 4:1 CH2Cl2/MeOH; 87%; (c) TMSOTf, 4 A HW-300 MS, CH2Cl2, )50 ꢁC, 3 h; 71%; (d) PdCl2,
ꢂ
3:2 MeOH/CH2Cl2, rt, 4 h; 92%; (e) TMSOTf, 4 A HW-300 MS, CH2Cl2, )50 ꢁC, 90 min; 70%; (f) (i) PdCl2, 1:1 MeOH/CH2Cl2, rt, overnight; (ii)
3.4 M NaOMe, 1:1 MeOH/CH2Cl2, rt, overnight; 72%.
which were converted into the same product by the
following acetylation. A more detailed analysis, per-
formed with NMR spectroscopy, of the de-O-allylation
products, revealed that treatment of 9 with PdCl2
induced a partial migration of the acetyl group from 2B-
O- to 3B-O-position. This disclosed a crucial problem for
the completion of the synthesis, that was based on the
possibility of smoothly removing a 3-O-allyl group,
contiguous to a 2-O-acetyl group, at trisaccharide level.
Thus, it was decided to couple acceptor 10 not with
donor 8, but with the 2-O-benzoylated donor 12, since
benzoyl groups are usually less prone to give acyl
migration than acetates.27 In fact, a test PdCl2 deallyl-
ation on benzoylated 4 afforded cleavage of allyl group
with no acyl migration. Glycosyl donor 12 was therefore
synthesized from 4, by benzoylation, acetolysis, ano-
meric acetate cleavage (58% yield over three steps) and
conversion of the hemiacetal 11 into tricholoracetimi-
date (55%) (Scheme 1).
affording 15 (JCꢀ1;Hꢀ1 ¼ 173 Hz) with 70% yield. The
target methyl tetrasaccharide 16 was then finally ob-
tained by a two-steps deprotection (de-O-allylation and
ꢁ
Zemplen deacylation) in 72% yield. NMR chemical
shifts for 16 and the natural O-chain show good
1
accordance (see Section 3).28 The H NMR spectrum of
16 is shown in Figure 1 (Fig. 1).
In conclusion, a D-rhamnose branched tetrasaccha-
ride corresponding to the O-chain repeating unit from
P. syringae pv. cerasi 435, has been synthesized as its
methyl glycoside. It is noteworthy that the synthetic
approach used aimed also at the synthesis of a tetra-
saccharide building-block, whose protecting group pat-
tern could allow its smooth oligomerization to obtain
higher oligosaccharides suitable for structure–activity
studies. Work is in progress in this direction and results
will be published at due time, together with the biolog-
ical assays.
The ‘disarming’ nature of the benzoyl group on O-2 of
donor 12, required the use of TMSOTf as catalyst for
the coupling reaction with acceptor 10, that proceeded
at )50 ꢁC with 71% yield (Scheme 2). The a-configura-
tion of the new glycosidic bond was ascertained again by
a coupled HSQC experiment (JCꢀ1;Hꢀ1 ¼ 174 Hz). Tri-
saccharide 13 was then smoothly deallylated to alcohol
14 (92%), that was again coupled with donor 12,
3. Experimental
3.1. General methods
1H (400; 200 MHz) and 13C NMR (100; 50 MHz) spectra
were respectively recorded on a Bruker DRX-400 or on
a Varian XL-200 NMR, in CDCl3 (internal standard,

1910
E. Bedini et al. / Carbohydrate Research 339 (2004) 1907–1915
(C5), 55.1 (OMe), 17.7 (C6). ESI-MS for C14H18O6
(m=z): Mr (calcd) 282.11, Mr (found) 305.25 (M þ Na)þ.
Anal. Calcd C 59.57; H 6.43. Found: C 59.25; H 6.53.
3.3. Methyl 3-O-allyl-4-O-benzoyl-a-D-rhamnopyrano-
side (4)
A mixture of 3 (0.878 g, 3.14 mmol) and Bu2SnO
(0.978 g, 3.91 mmol) was suspended in 10:1 benzene/
methanol (23 mL) and then heated and stirred at 60 ꢁC.
After 90 min solvent was removed. The residue was
mixed under argon atmosphere with Bu4NBr (0.995 g,
3.21 mmol) and the solid mixture suspended in toluene
(12 mL). Allyl bromide (2.91 mL, 34.1 mmol) was added
and the mixture was stirred at 65 ꢁC. After 2 h the resi-
due was concentrated. Silica gel chromatography (7:1,
petroleum ether/ethyl acetate) of the residue afforded 4
Figure 1. 1H NMR spectrum (400 MHz, (CH3)2CO as internal stan-
dard) of the target tetrasaccharide 16.
1
for H: CHCl3 at d 7.26; for 13C: CDCl3 at d 77.0) or in
1
D2O (internal standard, for H and 13C: (CH3)2CO at d
(2.76 mmol, 88%) as a yellowish oil. ½aꢁ +42.0 (c 1.0,
D
1
2.22 and at d 31.5, respectively). Assignment of proton
and carbon chemical shifts for compounds 12–15 were
based on COSY, TOCSY, ROESY, HSQC and coupled
HSQC-COSY experiments. Positive ESI-MS spectra
were recorded on a Finnigan LCQ-DECA ion trap mass
spectrometer. Optical rotations were measured on a
JASCO P-1010 polarimeter. Elemental analysis were
performed on a Carlo Erba 1108 instrument. Analytical
thin layer chromatography (TLC) was performed on
aluminium plates precoated with Merck Silica Gel 60
F254 as the adsorbent. The plates were developed with
5% H2SO4 ethanolic solution and then heating to
130 ꢁC. Column chromatography was performed on
Kieselgel 60 (63–200 mesh). Gel filtration chromato-
graphy was performed on a Sephadex G-10 column
(1.0 · 20 cm) with H2O as eluant. Solvents used were
purchased from Fluka and not further purified before
use.
CH2Cl2); H NMR (200 MHz, CDCl3): d 8.10–7.40 (m,
5H, H-Ar), 5.72 (m, 1H, OCH2CH@CH2), 5.28 (t,
J4;3 ¼ J4;5 ¼ 9:8 Hz, 1H, H-4), 5.16 (br d, Jvic ¼ 17:4 Hz,
1H, OCH2CH@CH2 trans), 5.07 (br d, Jvic ¼ 10:2 Hz,
1H, OCH2CH@CH2 cis), 4.78 (br s, 1H, H-1), 4.16–3.89
(m, 4H, H-2, H-5, OCH2CH@CH2), 3.81 (dd,
J3;4 ¼ 9:8 Hz, J3;2 ¼ 3:4 Hz, 1H, H-3), 3.41 (s, 3H, OMe),
1.25 (d, J6;5 ¼ 6:4 Hz, 3H, H-6). 13C NMR (50 MHz,
CDCl3): d 165.7 (C@O), 134.1 (OCH2CH@CH2), 133.1
(Cipso), 129.7–128.4 (CAAr), 117.7 (OCH2CH@CH2),
100.2 (C-1), 76.6 (C-3), 73.1, 71.0, 68.7, 66.1 (C-2, C-4,
C-5, OCH2CH@CH2), 55.0 (OMe), 17.5 (C-6). ESI-MS
for C17H22O6 (m=z): Mr (calcd) 322.14, Mr (found) 345.39
(M þ Na)þ. Anal. Calcd C 63.34; H 6.88. Found: C
63.45; H 6.99.
3.4. Methyl 3-O-allyl-4-O-benzoyl-2-O-levulinoyl-a-D-
rhamnopyranoside (5)
3.2. Methyl 4-O-benzoyl-a-
D
-rhamnopyranoside (3)
To a solution of 4 (0.499 g, 1.55 mmol) in CH2Cl2
(11 mL), levulinic acid (1.0 mL, 8.64 mmol), DMAP
(0.120 g, 0.98 mmol) and then DIPC (1.6 mL,
10.2 mmol) were added. The mixture was stirred at rt for
600, after that it was filtered over a Celite pad, washed
with water, dried and concentrated to afford a brown
residue. Silica gel chromatography (6:1, petroleum
ether/ethyl acetate) of the residue afforded 5 (0.516 g,
To a 0 ꢁC cooled solution of 2 (0.869 g, 4.02 mmol) in
pyridine (5.8 mL), BzCl (1.3 mL, 10.9 mmol) was added
and the mixture was stirred at 0 ꢁC for 1 h, after that
CH2Cl2 (20 mL) was added. The mixture was washed
with 0.5 M HCl. The organic phase was collected, dried
and concentrated to afford a brown residue, that was
subsequently suspended in 4:1 TFA/H2O (9 mL) and
stirred at rt. After 20 min the mixture was concentrated
to give a residue, that, after silica gel chromatography
(2:1, petroleum ether/ethyl acetate), afforded 3 (0.878 g,
1
79%) as a yellowish oil. ½aꢁ )3.3 (c 0.7, CH2Cl2); H
D
NMR (200 MHz, CDCl3): d 8.08–7.40 (m, 5H, H-Ar),
5.65 (m, 1H, OCH2CH@CH2), 5.30 (dd, J2;3 ¼ 3:2 Hz,
J2;1 ¼ 1:6 Hz, 1H, H-2), 5.22 (t, J4;3 ¼ J4;5 ¼ 10:0 Hz, 1H,
H-4), 5.13 (br d, Jvic ¼ 17:4 Hz, 1H, OCH2CH@CH2
trans), 5.02 (br d, Jvic ¼ 10:4 Hz, 1H, OCH2CH@CH2
cis), 4.67 (br s, 1H, H-1), 4.12–3.81 (m, 4H, H-3, H-5,
OCH2CH@CH2), 3.39 (s, 3H, OMe), 2.82–2.62 (m, 4H,
CH2CH2), 2.20 (s, 3H, CH3CO), 1.25 (d, J6;5 ¼ 6:2 Hz,
3H, H-6). 13C NMR (50 MHz, CDCl3): d 206.3
(CH3C@O), 171.9 (C@OLev), 165.6 (C@OBz), 134.3
1
77%) as a white foam. ½aꢁ +114.5 (c 1.0, CH2Cl2); H
D
NMR (200 MHz, CDCl3): d 8.10–7.41 (m, 5H, H-Ar),
5.04 (t, J4;3 ¼ J4;5 ¼ 9:8 Hz, 1H, H-4), 4.77 (br s, 1H, H-
1), 4.14–3.91 (m, 3H, H-2, H-3, H-5), 3.42 (s, 3H, OMe),
1.30 (d, J6;5 ¼ 6:2 Hz, 3H, H-6). 13C NMR (50 MHz,
CDCl3): d 167.5 (C@O), 133.5 (Cipso), 129.8–128.5
(CAAr), 100.4 (C-1), 70.8, 70.6, 70.4 (C2, C3, C4), 65.5

E. Bedini et al. / Carbohydrate Research 339 (2004) 1907–1915
1911
(OCH2CH@CH2), 133.1 (Cipso), 130.0–128.4 (CAAr),
117.2 (OCH2CH@CH2), 98.7 (C-1), 74.4, 73.1, 70.5,
69.0, 66.4 (C-2, C-3, C-4, C-5, OCH2CH@CH2), 55.1
(OMe), 38.0, 29.8, 28.2 CH2CH2, CH3C@O), 17.6 (C-6).
ESI-MS for C22H28O8 (m=z): Mr (calcd) 420.18, Mr
(found) 443.40 (M þ Na)þ. Anal. Calcd C 62.85; H 6.71.
Found: C 62.95; H 6.78.
Jvic ¼ 10:2 Hz, Jgem ¼ 1:5 Hz, 1H, OCH2CH@CH2 cis),
4.21 (dq, J5;4 ¼ 9:9 Hz, J5;6 ¼ 6:2 Hz, 1H, H-5), 4.17-3.94
(m, 3H, H-3, OCH2CH@CH2), 2.24 (s, 3H, CH3CO),
1.25 (d, J6;5 ¼ 6:2 Hz, 3H, H-6). 13C NMR (50 MHz,
CDCl3; a-anomer): d 170.3 (C@OAc), 166.5 (C@OBz),
134.1 (OCH2CH@CH2), 133.2 (Cipso), 129.8–128.5
(CAAr), 117.3 (OCH2CH@CH2), 93.0 (C-1), 74.4, 73.2,
70.4, 70.2, 66.9 (C-2, C-3, C-4, C-5, OCH2CH@CH2),
20.4 (CH3C@OAc), 17.7 (C-6). ESI-MS for C18H22O7
(m=z): Mr (calcd) 350.14, Mr (found) 373.27 (M þ Na)þ.
Anal. Calcd C 61.71; H 6.33. Found: C 61.88; H 6.20.
3.5. Methyl 4-O-benzoyl-2-O-levulinoyl-a-D-rhamnopyr-
anoside (6)
Compound 5 (0.487 g, 1.16 mmol) was dissolved in 3:2
MeOH/CH2Cl2 (20 mL) and PdCl2 (82 mg, 0.46 mmol)
was added. The mixture was stirred at rt overnight, after
that it was filtered over a Celite pad, washed with 5 N
NaCl, dried and concentrated. Silica gel chromatogra-
phy (4:1, petroleum ether/ethyl acetate) afforded 6
3.7. 2-O-Acetyl-3-O-allyl-4-O-benzoyl-a-D-rhamnopyr-
anosyl trichloroacetimidate (8)
To a 0 ꢁC cooled solution of 7 (0.429 g, 1.23 mmol) in
CH2Cl2 (10 mL), Cl3CCN (0.610 mL, 6.08 mmol) and
DBU (0.105 mL, 0.703 mmol) were added under argon
atmosphere. After 60 min stirring at 0 ꢁC, the solution
was concentrated at 20 ꢁC. Silica gel chromatography
(14:1 petroleum ether/ethyl acetate) of the residue
(0.346 g, 78%) as a white foam. ½aꢁ +30.8 (c 0.9,
D
1
CH2Cl2); H NMR (200 MHz, CDCl3): d 8.12–7.41 (m,
5H, H-Ar), 5.19 (dd, J2;3 ¼ 3:2 Hz, J2;1 ¼ 1:6 Hz, 1H, H-
2), 5.09 (t, J4;3 ¼ J4;5 ¼ 10:0 Hz, 1H, H-4), 4.69 (br s, 1H,
H-1), 4.23–3.88 (m, 2H, H-3, H-5), 3.40 (s, 3H, OMe),
2.86–2.65 (m, 4H, CH2CH2), 2.22 (s, 3H, CH3CO), 1.27
(d, J6;5 ¼ 6:2 Hz, 3H, H-6). 13C NMR (50 MHz, CDCl3):
d 207.0 (CH3C@O), 172.2 (C@OLev), 166.7 (C@OBz),
133.3 (Cipso), 129.8–128.4 (CAAr), 98.4 (C-1), 75.3, 72.7,
68.7, 66.1 (C-2, C-3, C-4, C-5), 55.2 (OMe), 38.3, 29.8,
28.3 (CH2CH2, CH3C@O), 17.6 (C-6). ESI-MS for
C19H24O8 (m=z): Mr (calcd) 380.15, Mr (found) 403.37
(M þ Na)þ. Anal. Calcd C 59.99; H 6.36. Found: C
60.18; H 6.29.
afforded 8 (0.435 g, 72%) as a yellowish oil. ½aꢁ +14.4 (c
D
1
1.0, CH2Cl2); H NMR (200 MHz, CDCl3): d 8.73 (s,
1H, NH), 8.10–7.44 (m, 5H, H-Ar), 6.25 (d, J1;2
¼
2:0 Hz, H-1), 5.68 (m, 1H, OCH2CH@CH2), 5.51 (dd,
J2;3 ¼ 3:2 Hz, J2;1 ¼ 2:0 Hz, 1H, H-2), 5.37 (t,
J4;3 ¼ J4;5 ¼ 10:0 Hz, 1H, H-4), 5.16 (dd, Jvic ¼ 17:4 Hz,
Jgem ¼ 1:6 Hz, 1H, OCH2CH@CH2 trans), 5.08 (dd,
Jvic ¼ 10:2 Hz, Jgem ¼ 1:6 Hz, 1H, OCH2CH@CH2 cis),
4.23–3.90 (m, 4H, H-3, H-5, OCH2CH@CH2), 2.21 (s,
3H, CH3C@OAc), 1.30 (d, J6;5 ¼ 6:2 Hz, 3H, H-6). 13C
NMR (50 MHz, CDCl3): d 170.1 (C@OAc), 165.6
(C@OBz), 159.9 (C@NH), 134.0 (OCH2CH@CH2),
3.6. 2-O-Acetyl-3-O-allyl-4-O-benzoyl-D-rhamnopyra-
nose (7)
133.3
(Cipso),
129.8–128.5
(CAAr),
118.0
(OCH2CH@CH2), 95.1 (C-1), 77.2 (C-3), 72.2, 70.9,
69.7, 67.4 (C-2, C-4, C-5, OCH2CH@CH2), 20.9
(CH3C@O), 17.6 (C-6). ESI-MS for C20H22Cl3NO7
(m=z): Mr (calcd) 493.05, Mr (found) 516.41 (M þ Na)þ.
Anal. Calcd C 48.55; H 4.48; N 2.83. Found: C 49.00; H
4.44; N.2.78.
Compound 4 (1.337 g, 4.15 mmol) was dissolved in Ac2O
(10 mL). To this solution 25:20:0.5 v/v/v Ac2O/AcOH/
H2SO4 (18 mL) was added. The solution was stirred for
30 min at rt, then water (5.0 mL) was dropwise added
and stirring was continued for additional 10 min, after
that the solution was diluted with CH2Cl2 (400 mL).
After successive washings with water, 1 M NaHCO3 and
then with water again, the organic layer was collected,
dried and concentrated. The residue was dissolved in
DMF (15 mL) and then hydrazine acetate (0.295 g,
3.11 mmol) was added. After 40 min stirring at rt, the
solution was diluted with CH2Cl2 (400 mL) and washed
with 5 N NaCl, dried and concentrated to give a residue,
that after silica gel chromatography (5:1 petroleum
3.8. Methyl (2-O-acetyl-3-O-allyl-4-O-benzoyl-a-
rhamnopyranosyl)-(1 fi 3)-4-O-benzoyl-2-O-levulinoyl-a-
-rhamnopyranoside (9)
D-
D
A suspension of acceptor 6 (0.243 g, 0.64 mmol), imidate
ꢂ
8 (0.413 g, 0.84 mmol) and freshly powdered 4 A HW-
300 molecular sieves in CH2Cl2 (15 mL) was stirred at
)50 ꢁC under argon atmosphere. BF3ÆOEt2 (32 lL,
0.25 mmol) was added and the mixture was kept at
)50 ꢁC for 150 min, after that it was filtered on a Celite
pad and washed with 1 M NaHCO3 and water. The
organic layer was collected, dried and concentrated.
Silica gel chromatography (3:1, petroleum ether/ethyl
acetate) of the residue afforded 9 (0.389 g, 86%) as a
ether/ethyl acetate), afforded
7
(0.858 g, 59%;
1
a=b ¼ 3:5=1) as a yellowish oil. H NMR (200 MHz,
CDCl3; a-anomer): d 8.09–7.43 (m, 5H, H-Ar), 5.68 (m,
1H, OCH2CH@CH2), 5.36 (dd, J2;3 ¼ 3:3 Hz,
J2;1 ¼ 1:8 Hz, 1H, H-2), 5.28 (t, J4;3 ¼ J4;5 ¼ 9:9 Hz, 1H,
H-4), 5.22 (br s, 1H, H-1), 5.16 (dd, Jvic ¼ 17:4 Hz,
Jgem ¼ 1:5 Hz, 1H, OCH2CH@CH2 trans), 5.05 (dd,
white foam. ½aꢁ )21.4 (c 1.0, CH2Cl2); 1H NMR
D

1912
E. Bedini et al. / Carbohydrate Research 339 (2004) 1907–1915
(200 MHz, CDCl3): d 8.10–7.41 (m, 10H, H-Ar), 5.52
(m, 1H, OCH2CH@CH2), 5.34 (t, J4;3 ¼ J4;5 ¼ 9:8 Hz,
1H, H-4A), 5.27 (dd, J2;3 ¼ 3:2 Hz, J2;1 ¼ 1:6 Hz, 1H, H-
2A), 5.13 (t, J4;3 ¼ J4;5 ¼ 10:0 Hz, 1H, H-4B), 5.02–4.85
(m, 3H, H-2B, OCH2CH@CH2), 4.69 (br s, 1H, H-1A),
4.67 (br s, 1H, H-1B), 4.26 (dd, J3;4 ¼ 10:2 Hz,
J3;2 ¼ 3:2 Hz, 1H, H-3A), 3.96 (m, 2H, H-5A, H-5B),
3.84–3.63 (3H, H-3B, OCH2CH@CH2), 3.41 (OMe),
2.77 (m, 4H, CH2H2), 2.21 (s, 3H, CH3C@OLev), 1.92 (s,
3H, CH3 C@OAc), 1.29 (d, J6;5 ¼ 6:2 Hz, 3H, H-6A),
1.19 (d, J6;5 ¼ 6:2 Hz, 3H, H-6B). 13C NMR (50 MHz,
CDCl3): d 206.6 (CH3C@O), 171.8 (C@OLev), 169.6
(C@OAc), 165.7 (C@OBz), 134.1 (OCH2CH@CH2),
133.4, 133.0 (2Cipso), 129.8–128.3 (C-Ar), 117.0
77.2 (C-3A), 73.0, 71.4, 70.8, 69.7, 68.4, 67.4, 66.3 (C-2A,
C-2B, C-3B, C-4A, C-4B, C-5A, C-5B), 55.1 (OMe), 20.5,
20.4 (2CH3C@OAc), 17.5, 17.4 (C-6A, C-6B). ESI-MS
for C31H36O13 (m=z): Mr (calcd) 616.22, Mr (found)
639.31 (M þ Na)þ. Anal. Calcd C 60.38; H 5.88. Found:
C 60.55; H 6.00.
3.10. 3-O-Allyl-2,4-di-O-benzoyl-D-rhamnopyranose (11)
Compound 4 (0.982 g, 3.05 mmol) was dissolved in
pyridine (5.0 mL) and then BzCl (0.710 mL, 6.14 mmol)
was added. The mixture was stirred for 30 min, water
(20 mL) was then added. After 100 additional stirring it
was diluted with CH2Cl2 (100 mL) and washed with
0.5 M HCl. The organic layer was collected, dried and
concentrated to give a residue that was suspended in
Ac2O (7.5 mL). 25:20:0.5 v/v/v Ac2O/AcOH/H2SO4
(12.5 mL) was added and the solution was stirred for 600
at rt. Water (5.0 mL) was then dropwise added and after
50 additional stirring the mixture was diluted with
CH2Cl2 (300 mL) and washed with 5 M NaCl, 1M
NaHCO3 and water. The organic layer was collected,
dried and concentrated to give a yellowish oil, that was
dissolved in DMF (15 mL). Hydrazine acetate (0.331 g,
3.46 mmol) was added and the mixture was stirred for
450 at rt, after that it was diluted with CH2Cl2 (400 mL)
and washed with 5 M NaCl, dried and concentrated.
Silica gel chromatography (5:1, petroleum ether/ethyl
acetate) of the residue afforded 11 (0.733 g, 58%;
a=b ¼ 5 : 1) as a colourless oil. 1H NMR (200 MHz,
CDCl3; a-anomer): d 8.14–7.42 (m, 10H, H-Ar), 5.66
(m, 1H, OCH2CH@CH2), 5.58 (dd, J2;3 ¼ 3:3 Hz,
J2;1 ¼ 1:8 Hz, 1H, H-2), 5.43 (t, J4;3 ¼ J4;5 ¼ 9:8 Hz, 1H,
H-4), 5.38 (br s, 1H, H-1), 5.15 (dd, Jvic ¼ 17:2 Hz,
Jgem ¼ 1:6 Hz, 1H, OCH2CH@CH2 trans), 5.03 (dd,
Jvic ¼ 10:4 Hz, Jgem ¼ 1:6 Hz, 1H, OCH2CH@CH2 cis),
4.27 (dq, J5;4 ¼ 9:8 Hz, J5;6 ¼ 6:2 Hz, 1H, H-5), 4.17–
3.91 (m, 3H, H-3, OCH2CH@CH2), 1.30 (d,
J6;5 ¼ 6:2 Hz, 3H, H-6). 13C NMR (50 MHz, CDCl3;
1
(OCH2CH@CH2), 99.8 (C-1B, JC;H ¼ 173 Hz), 98.3
(C-1A), 75.3, 74.0, 73.2, 72.9, 71.6, 70.5, 68.8, 67.5,
66.5 (C-2A, C-2B, C-3A, C-3B, C-4A, C-4B, C-5A, C-5B,
OCH2CH@CH2), 55.2 (OMe), 37.8, 29.8, 28.1
(CH2CH2, CH3C@OLev), 20.7 (CH3C@OAc), 17.5,
17.4 (C-6A, C-6B). ESI-MS for C37H44O14 (m=z): Mr
(calcd) 712.27, Mr (found) 735.49 (M þ Na)þ. Anal.
Calcd C 62.35; H 6.22. Found: C 62.50; H 6.34.
3.9. Methyl (2,3-di-O-acetyl-4-O-benzoyl-a-
pyranosyl)-(1 fi 3)-4-O-benzoyl-a-
(10)
D
-rhamno-
D-rhamnopyranoside
To a solution of 9 (0.350 g, 0.49 mmol) in 2:1 MeOH/
CH2Cl2 (8.6 mL), PdCl2 (18 mg, 0.10 mmol) was added
and the mixture was stirred vigorously at rt for 4 h. The
mixture was then filtered over a Celite pad, diluted with
CH2Cl2 (100 mL) and washed with 5 N NaCl. The or-
ganic layer was collected, dried and concentrated to
afford a brownish residue, that was dissolved in pyridine
(4.0 mL) and then Ac2O (4.0 mL) was added to the
mixture. The solution was stirred at rt overnight, then it
was concentrated, diluted with CH2Cl2 (100 mL) and
washed with 1 M HCl (100 mL) and 1 M NaHCO3
(100 mL). The organic layer was collected, dried and
concentrated. The residue was dissolved in 4:1 CH2Cl2/
MeOH (8.0 mL) and then hydrazine acetate (65 mg,
0.68 mmol) was added. The solution was stirred 4 h at rt,
then it was concentrated to give a residue, that, after
silica gel chromatography (4:1, petroleum ether/ethyl
acetate) afforded 10 (0.278 g, 87%) as a white foam.
a-anomer):
d
165.9,
165.7
(2C@O),
134.3
(OCH2CH@CH2), 133.3, 133.1 (2Cipso), 130.0–128.4
(CAAr), 117.4 (OCH2CH@CH2), 92.5 (C-1), 73.9, 73.3,
70.7, 70.0, 66.8 (C-2, C-3, C-4, C-5, OCH2CH@CH2),
17.8 (C-6). ESI-MS for C23H24O7 (m=z): Mr (calcd)
412.15, Mr (found) 435.38 (M þ Na)þ. Anal. Calcd C
66.98; H 5.87. Found: C 66.74; H 5.99.
½aꢁ +0.9 (c 1.0, CH2Cl2); 1H NMR (200 MHz, CDCl3): d
D
8.09–7.40 (m, 10H, H-Ar), 5.47–5.35 (m, 2H, H-4A, H-
3B), 5.23 (t, J4;3 ¼ J4;5 ¼ 9:6 Hz, 1H, H-4B), 5.02 (dd,
J2;3 ¼ 3:6 Hz, J2;1 ¼ 1:6 Hz, 1H, H-2B), 4.94 (d,
J1;2 ¼ 1:6 Hz, 1H, H-1B), 4.76 (br s, 1H, H-1A), 4.23–
4.05 (m, 3H, H-2A, H-3A, H-5B), 3.93 (dq, J5;4 ¼ 9:8 Hz,
J5;6 ¼ 6:2 Hz, 1H, H-5A), 3.43 (s, 3H, OMe), 1.90 (s, 3H,
CH3C@O), 1.79 (s, 3H, CH3C@O), 1.26 (m, 6H, H-6A,
H-6B). 13C NMR (50 MHz, CDCl3): d 169.5, 169.2
(2C@OAc), 165.6, 165.4 (2C@OBz), 133.4, 133.2
(2Cipso), 129.8–128.3 (CAAr), 100.3, 99.1 (C-1A, C-1B),
3.11. 3-O-Allyl-2,4-di-O-benzoyl-a-D-rhamnopyranosyl
trichloroacetimidate (12)
To a 0 ꢁC cooled solution of 11 (0.728 g, 1.77 mmol) in
CH2Cl2 (13 mL), Cl3CCN (0.890 mL, 8.88 mmol) and
DBU (0.152 mL, 1.02 mmol) were added under argon
atmosphere. After 60 min stirring at rt, the solution was
concentrated at 20 ꢁC. Silica gel chromatography (12:1,
petroleum ether/ethyl acetate) of the residue afforded 12

E. Bedini et al. / Carbohydrate Research 339 (2004) 1907–1915
1913
(0.539 g, 55%) as a white foam. ½aꢁ )50.3 (c 1.0,
1JC;H ¼ 174 Hz), 79.6 (C-2A), 77.2 (C-3A), 73.9, 73.3,
73.2, 71.5, 71.0, 70.1, 70.0, 68.5, 67.7, 67.6, 66.7 (C-2B,
C-2C, C-3A, C-3B, C-3C, C-4A, C-4B, C-4C, C-5A, C-5B,
C-5C, OCH2CH@CH2), 55.2 (OMe), 20.7, 20.4
(2CH3C@O), 17.8–17.7 (C-6A, C-6B, C-6C). ESI-MS for
C54H58O19 (m=z): Mr (calcd) 1010.36, Mr (found) 1033.70
(M þ Na)þ. Anal. Calcd C 64.15; H 5.78. Found: C
64.00; H 5.72.
D
1
CH2Cl2); H NMR (200 MHz, CDCl3): d 8.77 (s, 1H,
NH), 8.12–7.39 (m, 10H, H-Ar), 6.38 (d, J1;2 ¼ 2:0 Hz,
H-1), 5.72 (dd, J2;3 ¼ 3:4 Hz, J2;1 ¼ 2:0 Hz, 1H, H-2),
5.67
(m,
1H,
OCH2CH@CH2),
5.49
(t,
J4;3 ¼ J4;5 ¼10:0 Hz, 1H, H-4), 5.13 (dd, Jvic ¼ 17:4 Hz,
Jgem ¼ 1:6 Hz, 1H, OCH2CH@CH2 trans), 5.04 (dd,
Jvic ¼ 10:2 Hz, Jgem ¼ 1:6 Hz, 1H, OCH2CH@CH2 cis),
4.27-3.92 (m, 4H, H-3, H-5, OCH2CH@CH2), 1.33 (d,
J6;5 ¼ 6:0 Hz, 3H, H-6). 13C NMR (50 MHz, CDCl3): d
165.6, 165.4 (2C@OBz), 159.8 (C@NH), 134.0
(OCH2CH@CH2), 133.4, 133.2 (2Cipso), 129.9–128.4
(CAAr), 117.9 (OCH2CH@CH2), 95.1 (C-1), 73.9, 72.4,
70.9, 69.7, 68.0 (C-2, C-3, C-4, C-5, OCH2CH@CH2),
17.7 (C-6). ESI-MS for C25H24Cl3NO7 (m=z): Mr (calcd)
555.06, Mr (found) 578.17 (M þ Na)þ. Anal. Calcd C
53.93; H 4.34; N 2.52. Found: C 54.10; H 4.24; N 2.73.
3.13. Methyl (2,4-di-O-benzoyl-a-
(1 fi 2)-[2,3-di-O-acetyl-4-O-benzoyl- a-
anosyl-(1 fi 3)]-4-O-benzoyl-a- -rhamnopyranoside (14)
D
-rhamnopyranosyl)-
D
-rhamnopyr-
D
A solution of 13 (0.297 g, 0.29 mmol) in 3:2 MeOH/
CH2Cl2 (10 mL) was treated with PdCl2 (16 mg,
90 lmol). After 7 h stirring at rt, the mixture was filtered
on a Celite pad, diluted with CH2Cl2 (100 mL) and ex-
tracted with 5 M NaCl. The organic layer was collected,
dried and concentrated. The residue was subjected to
silica gel chromatography (5:1, petroleum ether/ethyl
3.12. Methyl (3-O-allyl-2,4-di-O-benzoyl-a-D-rhamno-
pyranosyl)-(1 fi 2)-[2,3-di-O-acetyl-4-O-benzoyl-a-
D-
-rhamnopyr-
rhamnopyranosyl-(1 fi 3)]-4-O-benzoyl-a-
D
acetate) to afford 14 (0.260 g, 92%) as a white foam. ½aꢁ
D
1
anoside (13)
)48.0 (c 1.0, CH2Cl2); H NMR (400 MHz, CDCl3): d
8.16–7.37 (H-Ar), 5.54 (m, 2H, H-2B, H-3C), 5.42 (m,
2H, H-4A, H-4B), 5.27 (t, J4;3 ¼ J4;5 ¼ 9:8 Hz, 1H, H-4C),
5.21 (d, J1;2 ¼ 1:9 Hz, 1H, H-1B), 5.08 (dd, J2;3 ¼ 3:2 Hz,
J2;1 ¼ 1:8 Hz, 1H, H-2C), 5.00 (d, J1;2 ¼ 1:8 Hz, 1H, H-
1C), 4.86 (d, J1;2 ¼ 1:6 Hz, 1H, H-1A), 4.58 (dd,
J3;4 ¼ 9:8 Hz, J3;2 ¼ 3:4 Hz, 1H, H-3B), 4.33–4.25 (m,
3H, H-3A, H-5B, H-5C), 4.06 (dd, J2;3 ¼ 3:2 Hz,
J2;1 ¼ 1:6 Hz, 1H, H-2A), 3.92 (dq, J5;4 ¼ 9:6 Hz,
J5;6 ¼ 6:0 Hz, 1H, H-5A), 3.43 (s, 3H, OMe), 1.89 (s, 3H,
CH3C@O), 1.70 (s, 3H, CH3C@O), 1.35–1.24 (m, 9H,
H-6A, H-6B, H-6C). 13C NMR (100 MHz, CDCl3): d
169.5, 169.0 (2C@OAc),166.4, 165.6, 165.5, 165.2
(4C@OBz), 133.1–133.0 (4Cipso), 129.7–128.2 (CAAr),
99.4–99.2 (C-1A, C-1B, C-1C), 79.2 (C-2A), 75.6 (C-3A),
74.4, 73.6, 73.2, 71.2, 69.7, 68.5, 67.9, 67.6, 67.5, 66.4 (C-
2B, C-2C, C-3A, C-3B, C-3C, C-4A, C-4B, C-4C, C-5A, C-
5B, C-5C), 54.9 (OMe), 20.4, 20.3 (2 CH3C@O), 17.6–
17.5 (C-6A, C-6B, C-6C). ESI-MS for C51H54O19 (m=z):
Mr (calcd) 970.33, Mr (found) 971.02 (M þ H)þ. Anal.
Calcd C 63.09; H 5.61. Found: C 63.09; H 5.58.
A suspension of acceptor 10 (0.271 g, 0.44 mmol), imi-
ꢂ
date 12 (0.342 g, 0.62 mmol) and freshly powdered 4 A
HW-300 molecular sieves in CH2Cl2 (16 mL) was stirred
at )50 ꢁC under argon atmosphere. TMSOTf (1.1 lL,
6.1 lmol) was added and the mixture was kept at
)50 ꢁC. After 60 min other TMSOTf (9.0 lL, 50 lmol)
was added and stirring was continued for additional 2 h,
after that the reaction was quenched by adding a drop of
Et3N. The mixture was then filtered on a Celite pad and
concentrated. Silica gel chromatography (6:1, petroleum
ether/ethyl acetate) of the residue afforded 13 (0.315 g,
1
71%) as a white foam. ½aꢁ )59.0 (c 1.0, CH2Cl2); H
D
NMR (400 MHz, CDCl3): d 8.15–7.29 (m, 20H, H-Ar),
5.76 (m, 1H, OCH2CH@CH2), 5.63 (dd, J2;3 ¼ 3:0 Hz,
J2;1 ¼ 1:6 Hz, 1H, H-2B), 5.50 (m, 2H, H-4A, H-3C),
5.42 (t, J4;3 ¼ J4;5 ¼ 9:8 Hz, 1H, H-4B), 5.30 (dd,
Jvic ¼ 17:2 Hz, Jgem ¼ 1:4 Hz, 1H, OCH2CH@CH2
trans), 5.26 (t, J4;3 ¼ J4;5 ¼ 9:9 Hz, 1H, H-4C), 5.22 (d,
J1;2 ¼ 1:6 Hz, 1H, H-1B), 5.15 (dd, Jvic ¼ 10:2 Hz,
Jgem ¼ 1:4 Hz, 1H, OCH2CH@CH2 cis), 5.05 (dd,
J2;3 ¼ 3:2 Hz, J2;1 ¼ 1:6 Hz, 1H, H-2C), 4.97 (d,
J1;2 ¼ 1:6 Hz, 1H, H-1C), 4.88 (d, J1;2 ¼ 1:5 Hz, 1H, H-
1A), 4.28–4.11 (m, 6H, H-3A, H-3C, H-5A, H-5C,
OCH2CH@CH2), 4.06 (dd, J2;3 ¼ 3:0 Hz, J2;1 ¼ 1:6 Hz,
1H, H-2A), 3.93 (dq, J5;4 ¼ 9:8 Hz, J5;6 ¼ 6:2 Hz, 1H, H-
5B), 3.42 (s, 3H, OMe), 1.94 (s, 3H, CH3C@O), 1.71 (s,
3H, CH3C@O), 1.34 (d, J6;5 ¼ 6:2 Hz, 3H, H-6B), 1.31
(d, J6;5 ¼ 6:2 Hz, 3H, H-6C), 1.27 (d, J6;5 ¼ 6:2 Hz,
3H, H-6A). 13C NMR (100 MHz, CDCl3): d 169.3,
169.0 (2C@OAc), 165.9-165.4 (4C@OBz), 134.1
(OCH2CH@CH2), 133.1–133.0 (4Cipso), 129.9–128.4
(CAAr), 118.2 (OCH2CH@CH2), 100.0, 99.9, 99.7
3.14. Methyl (3-O-allyl-2,4-di-O-benzoyl-a-
pyranosyl)-(1 fi 3)-(2,4-di-O-benzoyl-a- -rhamnopyra-
-rhamno-
-rhamnopyranoside
D-rhamno-
D
nosyl)-(1 fi 2)-[2,3-di-O-acetyl-4-O-benzoyl-a-
D
pyranosyl-(1 fi 3)]-4-O-benzoyl-a-
D
(15)
A suspension of acceptor 14 (0.212 g, 0.22 mmol), imi-
ꢂ
date 12 (0.165 g, 0.30 mmol) and freshly powdered 4 A
HW-300 molecular sieves in CH2Cl2 (10 mL) was stirred
at )50 ꢁC under argon atmosphere. TMSOTf (0.54 lL,
3.0 lmol) was added and the mixture was kept at
)50 ꢁC. After 900 the reaction was quenched by adding a
drop of Et3N. The mixture was then filtered on a Celite
1
1
(C-1A, C-1B, C-1C, JC;H ¼ 173 Hz, JC;H ¼ 173 Hz,

1914
E. Bedini et al. / Carbohydrate Research 339 (2004) 1907–1915
pad and concentrated. Silica gel chromatography (7:1,
petroleum ether/ethyl acetate) of the residue afforded 15
J2;3 ¼ 3:2 Hz, J2;3 ¼ 1:6 Hz 1H, H-2A), 3.89–3.85 (m,
2H, H-3A, H-3C), 3.82–3.76 (m, 2H, H-3B, H-5C), 3.74–
3.65 (m, 4H, H-3D, H-5A, H-5B, H-5D), 3.59 (t, 1H,
J4;3 ¼ J4;5 ¼ 9:6 Hz, 1H, H-4A), 3.55 (t, 1H,
J4;3 ¼ J4;5 ¼ 9:6 Hz, 1H, H-4C), 3.47 (m, 2H, H-4B, H-
4D), 3.41 (s, 3H, OMe), 1.30 (m, 12H, H-6A, H-6B, H-6C,
H-6D). 13C NMR (100 MHz, D2O):28 d 103.4 (C-1B, C-
1D), 103.0 (C-1C), 100.6 (C-1A), 79.5 (C-2A), 78.5 (C-3A,
C-3C), 73.3 (C-4A, C-4B), 73.2 (C-4D), 73.0 (C-4C), 71.5
(C-2B), 71.3 (C-2C), 71.2 (C-2D), 71.1 (C-3B, C-3D), 70.4
(C-5A, C-5B, C-5C, C-5D), 56.0 (OMe), 18.4–18.3 (C-6A,
C-6B, C-6C, C-6D). ESI-MS for C25H44O17 (m=z): Mr
(calcd) 616.26, Mr (found) 639.58 (M þ Na)þ. Anal.
Calcd C 48.70; H 7.19. Found: C 48.81; H 7.17.
(0.210 g, 70%) as a white foam. ½aꢁ )82.0 (c 1.0,
D
CH2Cl2);. 1H NMR (400 MHz, CDCl3): d 8.06–7.34 (H-
Ar), 5.67 (dd, J2;3 ¼ 3:2 Hz, J2;1 ¼ 1:6 Hz, 1H, H-2C),
5.64 (t, J2;3 ¼ 9:8 Hz, 1H, H-4C), 5.44 (m, 2H, H-3B, H-
4A), 5.33 (d, J2;1 ¼ 1:6 Hz, 1H, H-1C), 5.30–5.23 (m, 5H,
H-1C, H-1D, H-2D, H-4B, H-4D), 5.08 (dd, J2;3 ¼ 3:2 Hz,
J2;1 ¼ 1:6 Hz, 1H, H-2B), 4.96 (d, J2;1 ¼ 1:6 Hz, 1H, H-
1B), 4.87 (m, 2H, H-1A, OCH2CH@CH2 trans), 4.77 (dd,
Jvic ¼ 10:2 Hz, Jgem ¼ 1:4 Hz, 1H, OCH2CH@CH2 cis),
4.59 (dd, J3;4 ¼ 9:8 Hz, J3;2 ¼ 3:2 Hz, 1H, H-3C), 4.29
(dd, J3;4 ¼ 9:8 Hz, J3;2 ¼ 3:3 Hz, 1H, H-3A), 4.23 (m, 2H,
H-5B, H-5C), 4.08 (m, 2H, H-2A, H-5D), 3.93 (m, 1H, H-
5A), 3.83 (dd, J3;4 ¼ 9:8 Hz, J3;2 ¼ 3:4 Hz, 1H, H-3D),
3.75 (m, 1H, OCH2CH@CH2), 3.62 (m, 1H,
OCH2CH@CH2), 3.43 (s, 3H, OMe), 1.34 (m, 6H, H-6A,
H-6C) 1.26 (d, J6;5 ¼ 6:2 Hz, 3H, H-6B), 1.15 (d,
J6;5 ¼ 6:2 Hz, 3H, H-6D). 13C NMR (100 MHz, CDCl3):
d 169.2, 168.6 (2C@OAc), 166.0, 165.8, 165.3, 165.2,
165.0, 164.9 (6 C@OBz), 134.0 (OCH2CH@CH2),
133.4–132.8 (6Cipso), 129.8–128.1 (CAAr), 117.2
(OCH2CH@CH2), 100.0, 99.7, 99.6, 99.2 (C-1A, C-1B,
Acknowledgements
We thank Centro di Metodologie Chimico-Fisiche of
the University Federico II of Naples for the NMR
spectra, and MIUR, Rome (Progetti di Ricerca di In-
teresse Nazionale 2002, M.P.) for the financial support.
We also thank Mr. Salvatore Carbone for his precious
collaboration.
1
1
1
C-1C, C-1D, JC;H ¼ 173 Hz, JC;H ¼ 173 Hz, JC;H
¼
1
173 Hz, JC;H ¼ 174 Hz), 79.0 (C-2A), 76.4, 74.9, 73.8,
73.3, 72.9, 72.4, 71.5, 70.2, 70.0, 69.2, 68.4, 67.7, 67.6,
67.3, 66.9 (C-2B, C-2C, C-2D, C-3A, C-3B, C-3C, C-3D, C-
4A, C-4B, C-4C, C-4D, C-5A, C-5B, C-5C, C-5D,
OC2CH@CH2), 55.2 (OMe), 20.6, 20.2 (2CH3C@O),
17.8–17.5 (C-6A, C-6B, C-6C, C-6C). ESI-MS for
C74H76O25 (m=z): Mr (calcd) 1364.47, Mr (found) 1387.43
(M þ Na)þ. Anal. Calcd C 65.09; H 5.61. Found: C
66.01; H 5.48.
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