Synthetic tools for the characterization of galactofuranosyl transferases: Glycosylations via acylated glycosyl iodides

Article abstract of DOI:10.1016/j.carres.2013.03.032

With the aim of developing synthetic tools for the characterization of galactofuranosyltransferases, the synthesis of 9-decenyl glycosides of d-Manp, d-Galf, and β-d-Galf-(1→3)-d-Manp was targeted. The interest in the alkenyl aglycone arises via potential

Full text of DOI:10.1016/j.carres.2013.03.032

Carbohydrate Research 374 (2013) 75–81
Contents lists available at SciVerse ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Note
Synthetic tools for the characterization of galactofuranosyl
transferases: glycosylations via acylated glycosyl iodides
⇑
Luciana Baldoni, Carla Marino
CIHIDECAR-CONICET, Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina
a r t i c l e i n f o
a b s t r a c t
Article history:
With the aim of developing synthetic tools for the characterization of galactofuranosyltransferases, the
Received 18 December 2012
Received in revised form 26 March 2013
Accepted 28 March 2013
Available online 6 April 2013
synthesis of 9-decenyl glycosides of
est in the alkenyl aglycone arises via potential conjugation reactions, once the terminal double bond has
been conveniently functionalized. The glycosylation of b- -Galf-(1?3)- -Manp was attempted by two
different approaches: the trichloroacetimidate method and the glycosylation via the glycosyl iodide.
The conditions for the latter were established on the basis of glycosylation assays of per-O-acetylman-
nose. On the other hand, the study of glycosylation reactions via per-O-benzoylated galactofuranosyl
iodide confirms the versatility of glycosyl iodides as donors.
D-Manp, D-Galf, and b-D-Galf-(1?3)-D-Manp was targeted. The inter-
D
D
Keywords:
Mannopyranosyl iodide
per-O-Benzoylated-galactofuranosyl iodide
Ó 2013 Elsevier Ltd. All rights reserved.
per-O-tert-Butyldimethylsilyl-b-
D-
galactofuranose
Galactofuranosyl transferases
Among the numerous structures of pathogenic microorganisms
in which -Galf-
-galactofuranose occurs,1 the disaccharide b-
(1?3)- -Manp (1, Fig. 1) is found in glycoconjugates of protozoa
study the immunogenic activity of 1. For the synthesis of 2 it was
necessary to introduce the alkenyl moiety with a glycosylation
method that would preserve the Galf-(1?3)-Manp linkage. We
decided to carry on this synthesis by two alternative approaches:
one based on the trichloroacetimidate method, which required
transformations that we have previously applied,17,18 and the other
involving a glycosyl iodide donor (Scheme 1). In this case, the con-
ditions for the glycosylation of the acetylated mannose unit must be
established. For the glycobiological studies, we have also decided to
synthesize acceptors 3 and 4 (Fig. 1). The optimized conditions for
the synthesis of 3 would be useful for the glycosylation of 1. On
the other hand, as continuation of our studies on the scope of gly-
cosylations via galactofuranosyl iodides,18–20 this reaction was
investigated for the synthesis of compound 4 from acylated precur-
D
D
D
(Trypanosoma cruzi and Leishmania spp.) and in fungi, as Aspergillus
fumigatus.2,3 In T. cruzi, motif 1 is present as non-reducing terminal
units of the glycoinositolphospholipids (GIPLs),4–6 which are
important for the interaction with the intestine of the insect vec-
tor.7 In Leishmania, disaccharide 1 is present as an internal unit
in the lipophosphoglycan (LPG),8 which was also shown to play a
critical role in the attachment of Leishmania promastigotes to the
fly midgut.9
For elucidating the biosynthesis of
D-Galf containing glycocon-
jugates, synthetic substrates of the involved enzymes are
required.10–12 Oligosaccharides containing the b-
D-Galf-(1?3)-D-
Manp (1) motif have been synthesized,13,14 as well as some deriv-
atives of 1, which were afforded by different approaches.15 We
have described the synthesis of free disaccharide 1 using the glyco-
syl-aldonolactone approach, and we have shown that it is hydro-
sors of D-Galf. Thus, we report here the studies of glycosylations of
per-O-acetylmannose via glycosyl iodides, the exploration of the
galactofuranosylation via iodides prepared from per-O-acylated
precursors, and the synthesis of glycosyl disaccharide 2.
lyzed by the exo b-
our non-pathogenic model to evaluate the synthetic tools devel-
oped for studying the
-Galf related enzymes.16
With the aim of obtaining a derivative of 1 for the characteriza-
tion of the galactofuranosyltransferases of P. fellutanum and
D
-galactofuranosidase of Penicillium fellutanum,
For the synthesis of mannopyranoside 3 we used the glycosyl
iodide method starting from penta-O-acetyl-a,b-D-mannopyranose
D
(5). In the first instance, we established the reaction conditions for
the formation of the mannopyranosyl iodide and its subsequent
glycosylation, in order to apply similar conditions to the synthesis
of disaccharide 2. According to the reported conditions for similar
substrates,21,22 compound 5 was treated with TMSI (2.4 equiv) at
room temperature and after 2 h, the medium was neutralized with
EtN(iPr)2, and 9-decen-1-ol was added as an acceptor (Scheme 2).
Under these conditions, starting compound 5 was not completely
consumed, and the reaction proceeded slowly toward the
T. cruzi, we have now targeted the synthesis of 9-decenyl b-
Galf-(1?3)- -Manp (2, Fig. 1), which is expected to be an acceptor
of -Galf units and as precursor of other derivatives designed to
D-
D
D
⇑
Corresponding author. Tel./fax: +54 11 45763352.
E-mail address: cmarino@qo.fcen.uba.ar (C. Marino).
0008-6215/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.carres.2013.03.032

76
L. Baldoni, C. Marino / Carbohydrate Research 374 (2013) 75–81
OH
O
glycoside 8 was obtained as major product (46%), along with an
OH
O
HO
HO
HO
HO
important amount of partially de-O-acylated products. Therefore,
after reacetylation, compound 8 was obtained in 80% combined
yield (Table 1, entry 2). The NMR spectra of 8 showed that the gly-
cosylation occurred with complete 1,2-trans stereoselectivity, due
to participation of the neighboring acetyl group on O-2. O-Deacet-
ylation of crude compound 8 afforded 3 in 80% overall yield from 5.
The synthesis of 8 and 3 as precursors of oligosaccharides pres-
ent in the antigenic lipophosphoglycan of Leishmania donovani, had
been previously accomplished by the Koenigs–Knorr method from
acetobromomannose.27 The glycosyl iodide method here de-
scribed, besides avoiding the use of mercuric salts, affords 8 in
higher yield, and the complete NMR spectroscopic characterization
of both 8 and 3 is now provided.
O
O
O
O
OH
OH
OH
O
OH
OH
CH2OH
OH
OH
CH2OH
2
4
1
O
O
OH
OH
O
HO
HO
HO
OH
O
OH
CH2OH
3
Figure 1. Synthetic targets.
Previously, we have described the synthesis of per-O-TBS-b-D-
galactofuranose (9) and its glycosylation by in situ activation with
TMSI as the galactofuranosyl iodide 12 (Scheme 3). Compound 12
was effectively glycosylated to afford O-,18 S-, C-galactofurano-
sides,20 and some nitrogenated derivatives,19 under mild condi-
tions compatible with labile acceptors. Recently, the lipoteichoic
acid from Streptococcus sp. DSM 8747 has been synthesized by gly-
cosylation of 9 via the galactofuranosyl iodide, and the method
showed to be significantly more efficient than those using tradi-
tional glycosyl donors.28 Condensation of persilylated 9 with 9-de-
cen-1-ol under the conditions previously described,18 afforded
OR
OR
O
RO
O
OR
O
NH
O
Cl3C
OR
OR
OH
O
OR
HO
HO
OR
O
RO
O
OR
O
O
CH2OR
OR
O
1
OH
O
OH
OH
CH2OH
OR
OR
OR
CH2OR
OR
O
2
RO
glycoside 14 in 83% yield as an anomeric mixture b/a in a 3:1 ratio.
O
O
OR
I
A similar diastereoselectivity was observed with simple acceptors,
which was increased when bulky acceptors were used.18 O-Desily-
lation of 14 with TBAF afforded the free galactofuranoside 4 in 66%
yield.
OR
OR
CH2OR
Although b-D-galactofuranosides can be stereoselectively ob-
Scheme 1. Retrosynthetic approaches for 9-decenyl b-D-Galf-(1?3)-D-Manp (2).
tained by neighboring-group participation from acylated precur-
sors using SnCl4 or other Lewis acids3 as promoters, the glycosyl
acceptors are limited to acid stable derivatives. We aimed to inves-
tigate the scope of the galactofuranosyl iodide glycosylations from
the easily available peracylated Galf derivatives 1029 and 11,30
which are expected to give glycosides with higher diastereoselec-
tivity than 9, due to the anchimeric effect. In order to optimize
the reaction conditions, nBuOH was employed as a model acceptor.
As peracylated precursors are less reactive than persilylated,31–33
more drastic conditions than those employed for 9 would be re-
quired. The assayed conditions involving variations in the amounts
of TMSI, temperature, and reaction time are summarized in Table 2.
The effect of molecular sieves and promoters was also examined.
As expected, 11 was more reactive than 10, but less than 9 (Table 2,
entries 1–3). The best condition for the preparation of iodide 13, in
the absence of a catalyst or a promoter, was the treatment of 11
with 3 equiv of TMSI (Table 2, entry 5). Compound 10 required
4.5 equiv of TMSI to complete the reaction (Table 2, entry 4). Iodide
13 was not stable enough to be isolated.
formation of a main product, but on the basis of the 13C NMR spec-
trum, this compound was identified as the orthoesther 7 (Table 1,
entry 1).23,24
Attempts to rearrange the orthoesther 7 with TMSOTf25,26 were
not satisfactory; although the NMR spectra of the crude product
showed the formation of 8, a complex mixture of products has
been obtained as result of partial O-deacetylation.
It has been reported that ZnI2 accelerates the formation of per-
acylated glycosyl iodides and prevents the formation of the ort-
hoesther.21,22 The ZnI2 also acted as iodide source and in this
way the halogen exchange in the anomeric carbon, that would oc-
cur with other halogenated Lewis acids, was avoided. Hence, ZnI2
was added in a substoichiometric amount and iodide 6 was formed
in just 0.5 h (Table 1, entry 2). As the glycosylation of acylated io-
dides generally requires a promoter,23,24 after the complete trans-
formation of 5 into 6, an additional amount of ZnI2 was added
together with the 4 Å powdered molecular sieves. They were not
used in the first step because it has been reported that they retard
the iodide formation.23,24 Under these conditions the 9-decenyl
The addition of powdered molecular sieves during the second
step of the reaction avoided the formation of TMSOAc and
TMSOBz23,34 and the subsequent reaction with 13, which would af-
ford 10 and 11 as recombination products.
The effect of the addition of ZnI2 during the iodide formation
was also studied (Table 2, entries 6–8). In the presence of 0.6 equiv
of ZnI2, compound 13 was formed at room temperature with only
1.2 equiv of TMSI and in 0.5 h (Table 2, entry 8). When the amount
of ZnI2 was reduced, the consumption of acetate 11 was not com-
plete, although the formed iodide was consumed in 1 h (Table 2,
entries 7 and 8). The best results were obtained conducting the
reactions at room temperature, without the need of heating to
45 °C, as in the case of the mannopyranosyl iodide 6.
O(CH2)8CH=CH2
O
AcO
AcO
AcO
O
O
OAc
O
OAc
O
AcO
AcO
AcO
AcO
AcO
TMSI
promoter
9-decen-1-ol
7
AcO
promoter
MS 4Å
OAc
OR
RO
RO
RO
5
I
CH2Cl2
6
O
O(CH2)8CH=CH2
R = Ac
8
MeONa/MeOH 7%
99 %
3
CH2Cl2-MeOH
2:1
Under the optimized conditions established for the synthesis of 15
(Table 2, entry 8), the analogous decenyl glycoside 16 was obtained in
66% yield, mainly in the b-configuration (9:1). O-Debenzoylation of 16
R = H
Scheme 2. Synthesis of 9-decenyl a-D-mannopyranoside (3).

L. Baldoni, C. Marino / Carbohydrate Research 374 (2013) 75–81
77
Table 1
Reaction conditions assayed for glycosylation of penta-O-acetyl-D-mannopyranose (5) via mannosyl iodide
Entry
Iodide 6 formation
Glycosylation
Conditions
TMSI (equiv)
ZnI2 (equiv)
Conditions
Base/promoter (equiv)
MS 4 Å
Products/observations
1
2
2.4
1.5
25 °C, 2 h
45 °C, 0.5 h
EtN(iPr)2 (2.4)
ZnI2 (1.0)
—
Yes
25 °C, 144 h
45 °C, 3.5 h
7 (50%)
0.4
8 (46%) (80% after reacetylation)
I
O
OR1
O
O
OR1
ROH
OR1
OR2
OR2
TMSI, 4Å MS
1,3 equiv.
promoter
OR1
CH2Cl2, 0 ºC
promoter
OR1
OR1
rt
OR1
OR1
OR1
CH2OR1
CH2OR1
CH2OR1
14
β:α 3:1
β-anomer
16 R1 = Bz, R2 = -(CH2)8CH=CH2 β:α 9:1
NaOMe/MeOH
9 R1 = R2 = TBS β-anomer 12 R2 = TBS
R1 = TBS, R2 = -(CH2)8CH=CH2
15 R1 = Bz, R2 = nBu
13 R2 = Bz
10 R1 = R2 = Bz
11 R1 = Bz, R2 = Ac
SnCl4
Ac2O
TBAF,THF
87 %
4
R1 = H, R2 = -(CH2)8CH=CH2
94 %
Scheme 3. Synthesis of O-galactofuranosides via in situ formed galactofuranosyl iodides.
Table 2
Reaction conditions assayed for O-glycosylations via in situ formed galactofuranosyl iodides. Compound numbers in bold.
Entry
Precursor
TMSI (equiv)
ZnI2 (equiv)
Conditions
MS 4 Å
Conversion to iodidea (%)
Products/observations
1
2
3
4
5
6
7
8
9
10
10
10
11
11
11
11
1.2
1.2
1.2
4.5
3.0
1.2
1.2
1.2
—
—
—
—
0 °C, 0.5 h
0 °C, 0.5 h
0 °C, 0.5 h
0?25 °C, 1 h
0?25 °C, 1.5 h
0?25 °C, 0.5 h
0?25 °C, 1-2 h
0?25 °C, 1-2 h
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
100
0
20
100
100
100
80
14b:
—
15b
15b
15b
15b in 1 h (80%)
15b in 1 h
15b in 1 h
a 3:1
—
0.6
0.4
0.2
60
bIsolated by column chromatography.
a
Estimated by TLC.
with NaOMe/MeOH in CH2Cl2 afforded 4 in almost quantitative
yield. The b-configuration of the major component of 16 and 4 was
confirmed on the basis of the 13C NMR spectra, which showed char-
acteristic resonances for C-1 (105.6 and 109.4 ppm, respectively)
and signals corresponding to C-2 and C-4 above 80 ppm, also charac-
The 1H NMR spectrum showed singlets at 5.19 and 5.13 ppm
for H-10 of the b- and the
-anomers, respectively, and doublets
) and 4.52 ppm (H-1b) for the mannopyranosyl
a
at 4.90 (H-1
a
unit.
On the other hand, peracetylated compound 17 was treated
with TMSI/ZnI2, according to the conditions optimized for the for-
mation and glycosylation of iodide 6 (Table 1, entry 2), although a
greater amount of ZnI2 (0.7 equiv) was necessary to obtain iodide
19. Then, 9-decen-1-ol and 4 Å powdered molecular sieves were
added (Scheme 4). Compound 21 (78%) was obtained, along with
a small amount of 18.
teristic of the b-
Despite the convenience of the use of iodide 13 to achieve
stereoselectively b- -galactofuranosides, the disarmed character
of this benzoylated iodide was evidenced when allyl TMS, (TMS)2S,
or 2,4,6-tri-O-benzoyl- -manono-1,4-lactone were used as accep-
D-Galf configuration.
D
D
tors. While these compounds were effectively coupled with
9,18,20 the glycosylation of 13 failed.
In the 1H NMR spectrum of 21 obtained in this way, it was ob-
Both strategies designed to accomplish the synthesis of the
decenyl glycoside 2, required per-O-acetylated disaccharide 17,
which was afforded as an anomeric mixture in 75% yield by
treatment of 116 with Ac2O/py (Scheme 4). The approach involv-
ing a trichloroacetimidate donor required the selective anomeric
O-deacetylation of 17. Hence, 17 was treated with ethylenedia-
mine and acetic acid to afford the hemiacetal 18 in 84% yield
served that an anomeric mixture in a b/a ratio of 3:2 was actually
obtained. This ratio was almost equal to that obtained in the
glycosylation via the trichloroacetimidate 20, suggesting that the
stereoselectivity depends on the substrate itself rather than the
glycosylation method used. Probably, the b-
D-Galf unit as substitu-
ent on the O-3 of -Manp would be responsible for a distortion in
D
the intermediate bicyclic 1,2-acyloxonium ion, making the anchi-
meric participation less efficient.
Finally, de-O-acetylation of 21 with NaOMe/MeOH in CH2Cl2
afforded 2 in quantitative yield (Scheme 4). The 1H NMR spectrum
of 2, showed signals corresponding to H-10 (d 5.04 and 5.00) of both
anomers, which correlated with signals at 104.3 and 105.4 ppm in
(Scheme 4), exclusively in the
a-configuration as indicated by
the 1H NMR spectrum. Treatment of 18 with trichloroacetonitrile
and DBU afforded the trichloroacetimidate 20 (83%). Glycosyla-
tion of 20 with 1.5 equiv of 9-decen-1-ol in CH2Cl2 using TMSOTf
as catalyst gave 21 in 72% yield. The NMR spectra showed that,
despite the anchimeric assistance from the participating acetyl
group at O-2, compound 21 was obtained as an inseparable mix-
the HSQC experiment. The broad singlets at d 4.74 (H-1
(H-1b) corresponding to the Manp unit, correlated with signals at
99.9 (C-1b) and 99.7 (C-1 ) ppm. The assignment of the anomeric
a) and 4.47
ture of b/
showed resonances at 102.7 and 102.5 ppm corresponding to
C-10 of the b- and the
-anomers, respectively, and signals at d
99.6 (C-1b) and 99.2 (C-1 ) due to the mannopyranosyl unit.
a
anomers, in a 3:2 ratio. The 13C NMR spectrum
a
configuration in the Manp moiety was confirmed by a 2D NOESY
experiment which showed cross peaks between H-1/ H-3 and H-
1/H-5 for the b-anomer.
a
a

78
L. Baldoni, C. Marino / Carbohydrate Research 374 (2013) 75–81
OH
OH
OAc
OAc
OAc
OAc
O
O
O
HO
O
AcO
O
OAc
AcO
O
OAc
O
O
O
OH
OAc
Ac2O /Py
75 %
NH2CH2CH2NH2/HAcO
OH
OH
THF
overnight
OH
OAc
OAc
84 %
OAc
OH
CH2OH
OAc
CH2OAc
CH2OAc
1
18
17
TMSI, ZnI2
CH2Cl2, 45 ºC
DBU, Cl3CCN
CH2Cl2
83 %
OAc
OAc
OAc
O
OAc
O
AcO
AcO
O
OAc
O
O
O
OAc
NH
O
I
Cl3C
OAc
OAc
OAc
OAc
CH2OAc
CH2OAc
19
20
TMSOTf, MS
4Å
9-decen-1-ol
CH2Cl2, -78ºC
to rt
61%
RO
O
OR
72 %
9-decen-1-ol
MS 4Å, rt
OR
OR
O
O
O
OR
OR
CH2OR
R = Ac β/α 3:2
21
7% MeONa/MeOH
in 2:1 CH2Cl2/MeOH
100 %
2
R = H
Scheme 4. Synthesis of 9-decenyl b-D-Galf-(1?3)-D-Manp (2).
Since its development, the trichloroacetimidate glycosylation
a Perkin–Elmer 343 digital polarimeter. Nuclear magnetic reso-
nance (NMR) spectra were recorded with a Bruker AMX 500 spec-
trometer. Assignments of 1H and 13C were assisted by 2D 1H-COSY
and HSQC experiments. High resolution mass spectra (HRMS ESI+)
were recorded in a Bruker micrOTOF-Q II spectrometer.
method has been widely used as it has the advantage of being mild
enough to preserve other glycosidic linkages present in the accep-
tor or in the donor.35 This aspect is particularly critical in the case
of furanosyl units, due to their lability. Glycosyl iodides have long
been underused as they were considered too reactive to be of syn-
thetic utility. However, their use as glycosyl donors has been reval-
ued over the past 15 years mainly due to the development of new
methods of preparation.36 Our studies on the glycosylation via the
benzoylated galactofuranosyl iodide 13 confirm once more the ver-
satility of glycosyl iodides as donors.
1.2. 9-Decenyl 2,3,4,6-tetra-O-acetyl-a-D-mannopyanoside (8)
A suspension of 5 (0.1 g, 0.25 mmol) and ZnI2 (0.4 equiv,
0.032 g, 0.1 mmol) in anhydrous CH2Cl2 (10.0 mL) was stirred un-
der argon atmosphere at 0 °C for 15 min. TMSI (1.5 equiv,
For the synthesis of 2 by the trichloroacetimidate approach
compound 21 was obtained from 17 in three steps with the corre-
sponding column chromatography purifications in 50% overall
yield. The synthesis of 21 from 17 by means of the glycosyl iodide
strategy involved two reaction steps and two column chromatog-
raphy purifications, in 78% overall yield. Beyond the yield, the
advantage of the iodide approach was that the sequence was short-
er and the reaction times were significantly reduced. On the other
hand, in the synthesis of 2 via a mannosyl iodide, we demonstrated
50.0 lL, 0.375 mmol) was slowly added and the stirring was con-
tinued for another 15 min. The suspension was allowed to reach
room temperature and then heated at 45 °C. After 30 min of stir-
ring TLC analysis showed total consumption of the starting mate-
rial (Rf = 0.36, 1:1 hexane/EtOAc) and a single spot of Rf = 0.52
(1:1 hexane/EtOAc). Powdered molecular sieves 4 Å and 9-decen-
1-ol (0.14 mL, 0.75 mmol, 3.0 equiv) were added. After 3 h of
stirring at 45 °C and 18 h at room temperature, the solution was di-
luted with CH2Cl2 (250 mL), washed with NaHCO3 (ss)
(2 ꢀ 140 mL) and water (3 ꢀ 100 mL), dried (Na2SO4), and concen-
trated. The residue was purified by column chromatography
(3:1?3:2 hexane/EtOAc) affording syrupy compound 8 (0.056 g,
that a b-D-Galf unit in the glycosyl donor resists the glycosylation,
without degradation.
46%), Rf = 0.70 (1:1 hexane/EtOAc), ½a D
ꢁ
+38.4 (c 0.9, CHCl3). Lit.:27
+40 (c 1, CHCl3). Fractions of Rf = 0.34 (1:1 hexane/EtOAc) were
1. Experimental section
½aꢁD
reacetylated affording 195 in 80% overall yield. 1H NMR (CDCl3,
500 MHz) d 5.80 (m, 1H, CH@CH2), 5.34 (dd, J = 3.4, 10.0 Hz, 1H,
H-3, 5.26 (at, J = 10.0 Hz, 1H, H-4), 5.22 (dd, J = 1.7, 3.4 Hz, 1H, H-
2), 4.96 (m, 1H, CH@CHaH), 4.92 (m, 1H, CH@CHHb), 4.79 (d,
J = 1.7 Hz, 1H, H-1), 4.27 (dd, J = 5.3, 12.2 Hz, 1H, H-6), 4.09 (dd,
J = 2.3, 12.2 Hz, 1H, H-60), 3.97 (ddd, J = 2.3, 5.2, 10.0 Hz, 1H, H-5),
3.67 (m, 1H, OCHaH), 3.43 (dt, J = 6.6, 9.6 Hz, 1H, OCHHb), 2.14,
2.09, 2.03, 1.98, (4s, COCH3), 1.58 (CH2), 1.28 (CH2). 13C NMR
(CDCl3, 125,8 MHz) d 170.6, 170.1, 169.9, 169.7 (COCH3), 139.1
1.1. General synthetic methods
Analytical thin layer chromatography (TLC) was performed on
Silica Gel 60 F254 (Merck) aluminum supported plates (layer thick-
ness 0.2 mm) with solvent systems given in the text. Visualization
of the spots was effected by exposure to UV light and charring with
a solution of 10% (v/v) sulfuric acid in EtOH, containing 0.5% p-anis-
aldehyde. Column chromatography was carried out with Silica Gel
60 (230–400 mesh, Merck). Optical rotations were measured with

L. Baldoni, C. Marino / Carbohydrate Research 374 (2013) 75–81
79
(CH@CH2), 114.1 (CH@CH2), 97.5 (C-1), 69.7 (C-2), 69.1 (C-3), 68.5
(OCH2), 68.3 (C-5), 66.2 (C-4), 63.0 (OCH2), 62.5 (C-6), 33.7, 32.7,
29.3, 29.2, 29.0, 28.8, 26.0 (CH2), 20.9, 20.72, 20.67 ꢀ 2 (COCH3).
1H NMR data match with data reported in the lit.27 HRMS (ESI)
m/z calcd for C24H38NaO10 [M+Na]+: 509.2357. Found: 509.2376.
(Si(CH3)2). HRMS (ESI) m/z calcd for C40H86NaO6Si4 [M+Na]+:
797.53937. Found: 797.54188.
1.5. 9-Decenyl 2,3,5,6-tetra-O-benzoyl-b-D-galactofuranoside
(16)
1.3. 9-Decenyl
a
-
D
-mannopyranoside (3)
A suspension of 11 (0.20 g, 0.31 mmol) in anhydrous CH2Cl2
(10.0 mL) containing dry 4 Å powdered molecular sieves was
cooled to 0 °C and stirred for 10 min under Ar. TMSI (1.2 equiv,
0.048 mL, 0.37 mmol) and ZnI2 (0.6 equiv, 0.059 g, 0.18 mmol)
were added and the stirring was continued at 0 °C for 15 min
and then the suspension was allowed to reach room temperature.
After 0.5 h TLC monitoring showed complete transformation of 11
To a solution of 8 (0.05 g, 0.1 mmol) in anhydrous 2:1 CH2Cl2/
MeOH (10 mL) at 0 °C, 1.3 M NaOMe/MeOH (0.5 mL) was added.
After 1 h of stirring at 0 °C, the mixture was concentrated to
3 mL and deionized by elution with MeOH through a column of
strongly acidic cation exchange resin (H+). The eluate was evapo-
rated under reduced pressure to afford compound 3 (0.032 g,
(Rf = 0.61, 9:1 toluene/EtOAc) into
(Rf = 0.27), presumably 2,3,5,6-tetra-O-benzoyl-D
a
lower moving product
-Galf. 9-Decen-1-
99%) as a syrup, Rf = 0.65 (7:1:2 nPrOH/NH3/H2O), ½a D
ꢁ
+50 (c 0.9,
MeOH). Lit.:27 +56 (c 0.5, MeOH). 1H NMR (CD3OD, 500 MHz)
½
aꢁD
ol (1.3 equiv, 0.40 mmol, 0.072 mL) was added and the stirring
was continued for 1 h. Then, the suspension was filtered and the
filtrate was diluted with CH2Cl2 (250 mL), washed with NaHCO3
(ss) (2 ꢀ 140 mL) and water (3 ꢀ 100 mL), dried (Na2SO4), and con-
centrated. After purification by column chromatography (95:5 tol-
uene/EtOAc) fractions of Rf = 0.67 (9:1 toluene/EtOAc) afforded
d 5.81 (ddt, J = 6.8, 10.2, 13.9 Hz, 1H, CH@CH2), 4.98 (ddt, J = 1.6,
2.2, 17.1 Hz, 1H, CH@CHaH), 4.91 (ddt, J = 1.2, 2.3, 10.2 Hz, 1H,
CH@CHHb), 4.73 (d, J = 1.6 Hz, 1H, H-1), 3.82 (dd, J = 2.4, 11.8 Hz,
1H, H-6), 3.78 (dd, J = 1.7, 3.4 Hz, 1H, H-2), 3.73 (dt, J = 6.7,
9.6 Hz, 1H, OCHaH partially overlapped with H-60), 3.71 (dd,
J = 5.8, 11.8 Hz, 1H, H-60), 3.69 (dd, J = 3.4, 9.2 Hz, 1H, H-3), 3.61
(at, J = 9.5 Hz, 1H, H-4), 3.52 (ddd, J = 2.4, 5.8, 9.6 Hz, 1H, H-5),
3.41 (dt, J = 6.3, 9.7 Hz, 1H, OCHHb), 2.08ꢂ1.27 (CH2). 13C NMR
(CD3OD, 125.8 MHz) d 140.1 (CH@CH2), 114.7 (CH@CH2), 101.5
(C-1), 74.5 (C-5), 72.7 (C-3), 72.3 (C-2), 68.63 (OCH2), 68.56 (C-
4), 62.9 (C-6), 34.9, 30.6, 30.53, 30.50, 30.2, 30.1, 27.3 (CH2). 13C
NMR data match with data reported in the lit.27 HRMS (ESI) m/z
calcd for C16H30NaO6 [M+Na]+: 341.19346. Found: 341.19476.
syrupy compound 16 (0.15 g, 66%), ½a D
ꢁ
+10.3 (c 1.2, CHCl3). For
the b anomer: 1H NMR (CDCl3, 500 MHz) d 8.16ꢂ7.21 (aromatic),
6.08 (m, 1H, H-5), 5.81 (m, 1H, CH@CH2), 5.63 (d, J = 5.2 Hz, 1H,
H-3), 5.47 (s, 1H, H-2), 5.30 (s, 1H, H-1), 5.01ꢂ4.90 (m, 2H,
CH@CH2), 4.79ꢂ4.72 (m, 2H, H-6,60), 4.64 (m, 1H, H-4), 3.75 (m,
1H, OCHaH), 3.54 (m, 1H, OCHHb), 1.72ꢂ1.57 (CH2), 1.51ꢂ1.47
(CH2), 1.41ꢂ1.22 (CH2). 13C NMR (CDCl3, 125.8 MHz) d 166.1,
165.7, 165.6, 165.4 (COPh), 139.1 (CH@CH2), 133.42, 133.40,
133.29, 133.28, 133.2, 133.04, 133.03 (C-aromatic), 114.1
(CH@CH2), 105.6 (C-1), 82.0 (C-2), 81.2 (C-4), 77.6 (C-3), 70.3 (C-
5), 67.6 (OCH2), 63.5 (C-6), 40.3, 33.7, 29.3, 29.04, 29.02, 28.9,
26.6 (CH2). HRMS (ESI) m/z calcd for C44H46NaO10 [M+Na]+:
757.2983. Found: 757.2999.
1.4. 9-Decenyl 2,3,5,6-tetra-O-tert-butyldimethylsilyl-a,b-D-
galactofuranoside (14)
A
solution of 9 (0.20 g, 0.26 mmol) in anhydrous CH2Cl2
(10.0 mL) containing dry 4 Å powdered molecular sieves was
cooled to 0 °C and stirred for 10 min under Ar. Then, TMSI
(1.2 equiv, 0.042 mL, 0.32 mmol) was added and the solution was
stirred at 0 °C until TLC monitoring showed complete transforma-
tion of 9 into two lower moving products, the 1-iodo intermediate
12 (Rf = 0.70, 10:1 hexane/EtOAc) and some 2,3,5,6-tetra-O-TBS-
1.6. 9-Decenyl
a,b-D-galactofuranoside (4)
1.6.1. From 14
To a solution of compound 14 (0.077 g, 0.1 mmol) in freshly dis-
tilled THF (10.0 mL) cooled at 0 °C, TBAF (0.209 g, 0.8 mmol) was
added.18 The stirring was continued for 10 min at 0 °C and then
at room temperature for 1 h. The solution was evaporated and
the residue was purified by column chromatography (EtOAc). Frac-
a
,b-D-galactofuranose (Rf = 0.54), formed as a result of the hydroly-
sis of 12 on the silica gel plate.16 9-Decen-1-ol (1.3 equiv,
0.34 mmol, 0.061 mL) and EtN(iPr)2 (0.054 mL, 0.32 mmol), were
added by syringe. After stirring at room temperature for 2 h the
solution was diluted with CH2Cl2 (250 mL), washed with NaHCO3
(ss) (2 ꢀ 140 mL) and water (3 ꢀ 100 mL), dried (Na2SO4), and con-
centrated. The syrup obtained was purified by column chromatog-
raphy (99.7:0.3?99.5:0.5 hexane/EtOAc) affording syrupy
tions of Rf = 0.85 (7:1:2 nPrOH/NH3/H2O) gave compound
(0.028 g, 87%) as b/ ꢂ34.3 (c 0.8,
mixture in a 3:1 ratio, ½a D
CH3OH). 1H NMR (CD3OD, 500 MHz) d 5.81 (ddt, J = 6.7, 10.3,
17.1 Hz, 1.23H, CH@CH2 ,b), 4.98 (m, 2H, CH@CH2b), 4.91 (m,
0.89H, CH@CH2 ,b), 4.08 (at,
), 4.85ꢂ4.83 (m, 1.44H, H-1
J = 7.3 Hz, 0.44H, H-3 ), 4.00 (dd, J = 4.0, 6.7 Hz, 1H, H-3b), 3.94
(m, 0.44H, H-2 ), 3.93 (dd, J = 2.0, 4.0 Hz, 1H, H-2b), 3.91 (dd,
J = 3.3, 6.7 Hz, 1H, H-4b), 3.80 (dt, J = 6.9, 9.6 Hz, 0.44H, OCHaH ),
3.74ꢂ3.67 (m, 2.44H, H-4 , H-5b, OCHaHb), 3.65ꢂ3.58 (m, 2.88H,
H-5 , H-6
, H-6b, H-60b), 3.55 (m, 0.44H, H-60a), 3.46 (dt, J = 6.7,
4
a
ꢁ
a
compound 14 (0.167 g, 83%) as an inseparable b
a
mixture in a
a
a
3:1 ratio, which gave Rf = 0.40 (7:0.1 hexane/EtOAc twice devel-
a
oped), ½a D
ꢁ
ꢂ11.7 (c 1, CHCl3). 1H NMR (CDCl3, 500 MHz) d 5.81
a
(m, 1.29H, CH@CH2
1.29H, CH@CHHb
J = 2.6 Hz, 1H, H-1b), 4.20 (apparent t, J = 5.0 Hz, 0.36 H, H-3
a
,b), 4.99 (m, 1.29H, CH@CHaH
a
,b), 4.92 (m,
), 4.79 (d,
),
a
a
,b), 4.84 (d, J = 4.2 Hz, 0.36H, H-1
a
a
a
a
a
4.13 (dd, J = 3.6, 6.0 Hz, 1H, H-3b), 3.98 (dd, J = 2.5, 3.5 Hz, 1H, H-
2b), 3.94 (dd, J = 2.5, 6.0 Hz, 1H, H-4b), 3.90 (dd, J = 4.0, 5.2 Hz,
9.4 Hz, 0.44H, OCHHba), 3.41 (dt, J = 6.6, 9.6 Hz, 1H, OCHHbb),
2.08ꢂ1.27 (7 CH2). 13C NMR (CD3OD, 125.8 MHz)
d
140.1
), 84.1 (C-
), 78.7 (C-3b), 76.4 (C-
), 72.4 (C-5b), 69.7 (OCH2 ), 68.9 (OCH2b), 64.6
0.36H, H-2
(m, 2.6H, H-6
a
), 3.75 (m, 2.3H, H-5b, H-4
a
a
, H-5
a
, OCHaH
a), 3.67
(CH@CH2), 114.7 (CH@CH2), 109.4 (C-1b), 102.8 (C-1a
,b, OCHaHb), 3.57 (m, 1.43H, H-60a,b), 3.35 (dt,
4b), 83.5 (C-4a), 83.4 (C-2b), 78.9 (C-2a
J = 6.7, 9.6 Hz, 1H, OCHHbb), 3.28 (m, 0.32H, OCHHb
a
), 2.04ꢂ1.28
3a), 74.5 (C-5
a
a
(CH2
a
,b), 0.91ꢂ0.87 (SiC(CH3)3), 0.11ꢂ0.05 (Si(CH3)2). 13C NMR
(C-6b), 64.2 (C-6a), 34.9, 30.7, 30.6, 30.55, 30.49, 30.2, 30.1, 27.2
(CDCl3, 125.8 MHz)
CH@CH2
79.5 (C-3b), 78.8 (C-2
68.7 (OCH2 ), 68.0 (OCH2b), 65.2 (C-6
d
139.2 (2C, CH@CH2
a
,b), 114.1 (2C,
(CH2). HRMS (ESI) m/z calcd for C16H30NaO6 [M+Na]+: 341.19346.
a
,b), 108.0 (C-1b), 102.2 (C-1
), 76.4 (C-3 ), 73.5 (C-5
), 64.5 (C-6b), 33.8, 29.7,
a), 84.7 (C-2b), 83.8 (C-4b),
Found: 341.19470.
a
a
a), 73.3 (C-5b),
a
a
1.6.2. From 16
29.6, 29.5, 29.44, 29.42, 29.1, 29.08, 28.94, 28.92 (CH2),
26.2ꢂ25.7 (SiC(CH3)3), 18.4ꢂ17.8 (SiC(CH3)3), ꢂ3.5–(ꢂ5.4)
To a solution of compound 16 (0.073 g, 0.1 mmol) in anhydrous
3:2 CH2Cl2/MeOH (10 mL) at 0 °C, 1.3 M NaOMe/MeOH (0.4 mL)

80
L. Baldoni, C. Marino / Carbohydrate Research 374 (2013) 75–81
was added. After 1 h of stirring at 0 °C, the mixture was concen-
trated to 4 mL and deionized by elution with MeOH through a col-
umn of strongly acidic cation exchange resin (H+). The eluate was
1.9. 9-Decenyl 2,4,6-tri-O-acetyl-3-O-(2,3,5,6-tetra-O-acetyl-b-
D-
galactofuranosyl)- ,b- -mannopyranoside (21)
a
D
evaporated under reduced pressure to afford compound
4
(0.030 g, 94%) as a syrup, Rf = 0.9 (7:1:2 nPrOH/NH3/H2O), ½a D
ꢁ
1.9.1. Trichloroacetimidate method
To a stirred solution of 18 (0.16 g, 0.25 mmol) and trichloro-
acetonitrile (0.174 mL, 1.75 mmol) in anhydrous CH2Cl2 (15 mL)
ꢂ25.6 (c 1.1, MeOH). The NMR spectra showed that compound 4
was a mixture of anomers in 9:1 ratio.
cooled to 0 °C, DBU (15.5 lL, 0.1 mmol) was slowly added. After
1.7. 1,2,4,6-Tetra-O-acetyl-3-O-(2,3,5,6-tetra-O-acetyl-b-
D
-
1 h, the solution was carefully concentrated under reduced pres-
sure, and the residue was purified by column chromatography
(2:3 hexane/EtOAc) to give 0.163 g (83.4%) of the trichloroace-
timidate of 20 as a syrup, Rf = 0.63 (1:3 hexane/EtOAc). A stirred
suspension of 20 (163 mg, 0.208 mmol), 9-decen-1-ol (55 lL,
0.313 mmol), and 4 Å powdered molecular sieves (0.5 g) in anhy-
galactofuranosyl)- ,b- -mannopyranose (17)
a
D
To a solution of 1 (1.43 g, 4.19 mmol)19 in dry pyridine (10 mL)
cooled at 0 °C, Ac2O (4.74 mL, 50.26 mmol) was added dropwise,
and the mixture was stirred overnight at 5 °C. After cooling to
0 °C, the reaction was quenched by slow addition of water
(0.5 mL) and the stirring continued for 30 min at room tempera-
ture. The solution was diluted with CH2Cl2 (250 mL) and then suc-
cessively washed with HCl 10% (150 mL), NaHCO3 ss (150 mL), and
water (3 ꢀ 150 mL). The organic layer was dried (Na2SO4), filtered,
and then concentrated under reduced pressure. Purification of the
crude mixture by column chromatography (8:1 ?1:1 hexane/
EtOAc) afforded compound 17 (2.13 g, 75%) as an anomeric mix-
drous CH2Cl2 (15 mL) was cooled to ꢂ78 °C, and TMSOTf
(11.3 lL, 0.062 mmol) was slowly added. After 48 h of stirring
at room temperature, the mixture was quenched by addition of
NaHCO3 ss (10 mL) and then extracted with CH2Cl2. Purification
by column chromatography (2:1?1:1 hexane/EtOAc), afforded
syrupy 21 (0.11 g, 72%) as an anomeric mixture in 2:3
a/b ratio,
Rf = 0.58 (1:3 hexane/EtOAc), ½a D
ꢁ
ꢂ31.9 (c 1.2, CHCl3). 1H NMR
(CDCl3, 500 MHz) d 5.79 (m, 2.5H, CH@CH2
a
,b), 5.38ꢂ5.34 (m,
ture in 2:1
a
/b ratio, Rf = 0.55 (1:3 hexane/EtOAc), ½a D
ꢁ
ꢂ20.1 (c
2.5H, H-50a,b), 5.30 (at, J = 8.5 Hz, 1.5H, H-4b), 5.28 dd, J = 9.0,
0.9, CHCl3). 1H NMR (CDCl3, 500 MHz) d 6.09 (d, 1H, J = 2.0 Hz, H-
10.0 Hz, 1H, H-4a
), 5.19 (s, 1.5H, H-10b), 5.13 (s, 1H, H-10a),
1
a
), 5.80 (d, 0.4H, J = 1.2 Hz, H-1b), 5.51 (dd, 0.4H, J = 1.2, 3.7 Hz,
5.06 (dd, J = 2.1, 6.1 Hz, 1H, H-30a), 5.02ꢂ4.99 (m, 4.5H, H-20b,
H-2b), 5.40ꢂ5.33 (m, 1.4H, H-50a,b), 5.29 (m, 1H, H-2
a
),
CH@CHaHb, H-30b, 4.97 (m, 1H, CH@CHaH
a), 4.94 (dd, J = 0.6,
5.27ꢂ5.17 (m, 1.4H, H-4
a
,b), 5.14 (s, 1H, H-10a), 5.11 (s, 0.4H, H-
2.3 Hz, 1H, H-20a
,
4.93 (m, 1H, CH@CHHb
a
), 4.92ꢂ4.90 (m,
10b), 4.97ꢂ4.95 (m, 2.8H, H-20a,b, H-30a,b), 4.39 (dd, 1H, J = 4.5,
2.5H, CH@CHHbb, H-1a), 4.52 (d, J = 1.3 Hz, 1.5H, H-1b),
11.6 Hz, H-60a
a
), 4.37ꢂ4.25 (m, 1.8H, H-6a
a
,b, H-60ab), 4.20ꢂ4.12
4.37ꢂ4.15 (m, 11.5H, H-60a
a
,b, H-6a
a
,b, H-40a,b, H-60b
a,b, H-
(m, 4.2H, H-40a,b, H-60b
a
,b, H-6bb, H-3
a
), 4.09 (dd, 1H, J = 2.5,
6bb), 4.11 (dd, J = 1.4, 3.1 Hz, 1.5H, H-2b), 4.08 (dd, J = 2.4,
12.2 Hz, H-6b
a
), 4.03ꢂ3.97 (m, 1.4H, H-3b, H-5
a
), 3.77ꢂ3.73 (m,
12.3 Hz, 1H, H-6b
J = 6.8, 9.5 Hz, 1.5H, OCHaHb), 3.87 (ddd, J = 2.8, 5.3, 10.3 Hz,
1H, H-5 ), 3.82 (dd, J = 3.1, 9.0 Hz, 1.5H, H-3b), 3.65 (dt, J = 6.8,
9.8 Hz, 1H, OCHaH ), 3.59 (m, 1.5H, H-5b), 3.50 (dt, J = 6.8,
a
), 4.04ꢂ4.00 (m, 2H, H-2
a, H-3a), 3.91 (dt,
0.4H, H-5b), 2.17ꢂ2.05 (CH3CO). 13C NMR (CDCl3, 125.8 MHz) d
170.7, 170.4, 170.3, 169.96, 169.9, 169.2, 169.1, 169.06, 169.03
a
(CH3CO), 102.5 (C-10a), 102.2 (C-10b), 90.9 (C-1
a
), 90.8 (C-1b),
80.8, 80.7 (C-20a,b), 80.6 (2C, C-40a,b), 76.4 (2C, C-30a,b), 73.4 (C-
5b), 72.3 (C-3b), 70.6 (C-5 ), 70.5 (C-3
), 69.3 (2C, C-50a,b), 66.0
(C-2 ), 65.9 (2C, C-4
,b), 65.8 (C-2b), 62.5 (2C, C-60a,b), 62.2 (2C,
C-6
a
9.5 Hz,1.5H, OCHHbb), 3.42 (dt, J = 6.8, 9.8 Hz, 1H, OCHHba),
a
a
2.13ꢂ2.06 (CH3CO, CH2), 1.64ꢂ1.54 (CH2), 1.40ꢂ1.27 (CH2). 13C
NMR (CDCl3, 125.8 MHz) d 170.88, 170.84, 170.5, 170.4, 170.0,
169.99, 169.97, 169.7, 169.4, 169.1 (CH3CO), 139.2 (2C,
a
a
a
,b), 20.9, 20.8, 20.79, 20.77, 20.73, 20.71, 20.67, 20.66, 20.5
(CH3CO). HRMS (ESI) calcd for C28H38NaO19 [M+Na]+: 701.1900.
CH@CH2
0a), 99.6 (C-1b), 99.2 (C-1
(C-40b), 80.1 (C-40a), 76.1 (C-30b), 75.7 (C-30a), 75.0 (C-3b, 74.5
(C-3
), 72.2 (C-5b), 70.1 (OCH2), 69.28, 69.27 (C-50a,b), 68.3 (C-
), 68.1 (OCH2), 67.3 (C-2 ), 66.9 (C-4b), 66.8 (C-2b), 66.4 (C-
), 62.8 (C-60a), 62.7 (C-6 ), 62.6 (C-6b), 62.4 (C-60b),
a
,b), 114.2, 114.1 (CH@CH2
a
,b), 102.7 (C-10b), 102.5 (C-
Found 701.1897.
1
a
), 82.4 (C-20a), 81.6 (C-20b), 80.5
1.8. 2,4,6-Tri-O-acetyl-3-O-(2,3,5,6-tetra-O-acetyl-b-
galactofuranosyl)- -mannopyranose (18)
D
-
a
a
-D
5
4
a
a
a
a
To a stirred solution of ethylendiamine (0.025 mL, 0.38 mmol)
in THF (5 mL) cooled to 0 °C glacial acetic acid (0.025 mL,
0.46 mmol) was added dropwise. Immediately, this mixture was
transferred to a flask containing compound 17 (0.23 g, 0.34 mmol)
and the solution was stirred for 21 h at room temperature. The
mixture was diluted with CH2Cl2 (50 mL), washed with 5% HCl
(30 mL), NaHCO3 ss (30 mL), and water (3 ꢀ 30 mL). The organic
layer was dried (Na2SO4), filtered, and evaporated under reduced
pressure. Purification by column chromatography (2:3 hexane/
EtOAc) gave compound 18 in 84% yield (0.17 g), Rf = 0.28 (1:3 hex-
33.8ꢂ25.9 (CH2), 20.9ꢂ20.6 (CH3CO).
1.9.2. Glycosyl iodide method
A suspension of 17 (0.050 g, 0.074 mmol) and ZnI2 (0.038 g,
0.12 mmol) in anhydrous CH2Cl2 (10.0 mL) was stirred at 0 °C un-
der argon atmosphere. After 15 min TMSI (35 lL, 0.26 mmol) was
slowly added and the reaction was allowed to reach room temper-
ature. After 30 min of stirring at 45 °C TLC analysis showed total
consumption of starting material (Rf = 0.51, 1:3 hexane/EtOAc)
and a new compound of Rf = 0.64 (1:3 hexane/EtOAc), presumably
19. Powdered molecular sieves 4 Å (0.5 g) and 9-decen-1-ol
(0.04 mL, 0.22 mmol) were then added. After 17 h of stirring at
room temperature the reaction mixture was diluted with CH2Cl2
(250 mL), washed with NaHCO3 ss (2 ꢀ 140 mL), and H2O
(3 ꢀ 100 mL), dried (Na2SO4), and concentrated under reduced
pressure. The syrup was purified by silica gel column chromatogra-
phy (2:1?1:1 hexane/EtOAc) and fractions of Rf = 0.59 (1:3 hex-
ane/EtOAc) afforded compound 21 (0.034 g, 61%). By
reacetylation of the partial deprotected products formed during
the purification by column chromatography the yield was im-
proved (78%).
ane/EtOAc), ½a D
ꢁ
ꢂ12.7 (c 1, CHCl3). 1H NMR (CDCl3, 500 MHz) d
5.35 (dt, 1H, J = 2.9, 4.1 Hz, H-50), 5.30 (dd, 1H, J = 1.9, 3.5 Hz, H-
2), 5.23 (s, 1H, H-1), 5.21 (at, J = 9.9 Hz, 1H, H-4), 5.12 (s, 1H, H-
10), 4.96ꢂ4.93 (m, 2H, H-20, H-30), 4.33 (dd, 1H, J = 4.2, 11.9 Hz,
H-60a), 4.25ꢂ4.08 (m, 6H, H-3, H-6a, H-60b, H-40, H-5, H-6b). 13C
NMR (CDCl3, 125.8 MHz) d 170.8, 170.5, 170.3, 169.9, 169.3,
169.28, 169.25 (CH3CO), 102.2 (C-10), 92.4 (C-1), 80.8 (C-20), 80.5
(C-40), 76.5 (C-30), 70.3 (C-3), 69.3 (C-50), 68.5 (C-5), 67.5 (C-2),
66.6 (C-4), 62.6, 62.5 (C-6, C-60), 20.9, 20.79, 20.76, 20.75, 20.7,
20.5 (CH3CO). HRMS (ESI) calcd for C26H36NaO18 [M+Na]
659.1794. Found 659.1776.

L. Baldoni, C. Marino / Carbohydrate Research 374 (2013) 75–81
81
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1.10. 9-Decenyl 3-O-(b-D-galactofuranosyl)-a,b-D-
mannopyranoside (2)
To a solution of 21 (0.05 g, 0.064 mmol) in 2:1 anhydrous
CH2Cl2/MeOH (6 mL) stirred at 0 °C, 1.3 M NaOMe/MeOH
(0.75 mL) was added. After 1 h the solution was deionized by elu-
tion with MeOH through a column of strongly acidic cation ex-
change resin (H+). The eluate was evaporated and the residue
was dissolved in water and further purified through a RP18 car-
tridge. Compound 2 (0.031 g, 100%) was obtained as a 2:3
meric mixture, Rf = 0.62 (7:1:2 nPrOH/NH3/H2O), ½a D ꢂ12.7 (c 1,
MeOH). 1H NMR (D2O, 500 MHz) d 5.68 (m, 2.5H, CH@CH2
,b),
5.04 (s, 1.5H, H-10b), 5.00 (s, 1H, H-10a), 4.89 (dd, 2.5H, J = 6.5,
16.7 Hz, CH@CHaH ,b), 4.82 (m, 2.5H, CH@CHHb ,b), 4.74 (s, 1H,
H-1
H-20a
ab ano-
ꢁ
a
a
a
a
), 4.47 s, 1.5H, H-1b), 4.076 m, 1.5H, H-20b), 4.05 (m, 2.5H,
,
H-2b), 4.03ꢂ3.96 (m, 6H, H-30a,b, H-40a,b, H-2
a,
a, H-
3.81ꢂ3.66 (m, 11H, OCHaHb, H-50a,b, H-6a
a
,b, H-6b
a
,b, H-3
,b, H-3b, H-4b,
a), 3.33 (m, 1H, OCHHba), 3.24
4a
), 3.64ꢂ3.51 (m, 9H, OCHaH
a
, H-60a
a
,b, H-60b
a
3.50ꢂ3.43 (m, 2.5H, OCHHbb, H-5
(m, 1.5H, H-5b), 1.98ꢂ1.88, 1.57ꢂ1.45, 1.34ꢂ1.13 (7CH2). 13C
NMR (D2O, 125.8 MHz) d 139.0, 138.8 (CH@CH2), 114.16, 114.15
14. Ruda, K.; Lindberg, J.; Garegg, P. J.; Oscarson, S.; Konradsson, P. J. Am. Chem. Soc.
2000, 122, 11067–11072.
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311, 183–189.
17. Marino, C.; Lima, C.; Mariño, K.; Lederkremer, R. M. Beilstein J. Org. Chem. 2012,
8, 2142–2148.
(CH@CH2), 105.4 (C-10a), 104.3 (C-10b), 99.9(C-1b), 99.7 (C-1
a
),
83.3 (C-40a), 83.1 (C-40b), 81.3 (C-20b), 81.1 (C-20a), 77.5 (C-3b),
77.1 (2C, C-30a,b), 76.9 (C-3
),76.1 (C-5b), 72.5 (C-5 ), 70.8, 70.7
(2C, C-50a,b), 69.8 (OCH2b), 67.7 (OCH2
), 67.6 (C-2 ), 67.3 (C-
2b), 64.8 (C-4b), 64.6 (C-4 ,b),
), 62.8 (2C, C-60a,b), 60.9 (2C, C-6
a
a
a
a
a
a
33.7, 33.6 (CH2CH@CH2
a
,b), 29.4ꢂ25.7 (CH2). HRMS (ESI) calcd
for C22H41O11 [M+H]+ 481.26434. Found 481.26331.
18. Baldoni, L.; Marino, C. J. Org. Chem. 2009, 74, 1994–2003.
19. Baldoni, L.; Stortz, C. A.; Marino, C. Carbohydr. Res. 2011, 346, 191–196.
20. Baldoni, L.; Marino, C. Carbohydr. Res. 2012, 362, 70–78.
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Soc., Perkin Trans. 1 1995, 1977–1987.
Acknowledgments
The authors are indebted to the University of Buenos Aires,
Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT)
and the National Research Council of Argentina (CONICET). C.M. is
Research Members of CONICET, and L.B. was supported by a fellow-
ship from CONICET.
28. Sauvageau, J.; Foster, A. J.; Khan, A. A.; Chee, S. H.; Sims, I. M.; Timmer, M. S.;
Stocker, B. L. ChemBioChem 2012, 13, 2416–2424.
29. Repetto, E.; Marino, C.; Uhrig, M. L.; Varela, O. Bioorg. Med. Chem. 2009, 17,
2703–2711.
Supplementary data
Supplementary data associated with this article (1H and 13C
NMR spectra for compounds 2-4, 8, 14-18 and 21) can be found,
in the online version, at http://dx.doi.org/10.1016/j.carres.2013.03.
032.
30. Marino, C.; Gandolfi-Donadío, L.; Gallo-Rodriguez, C.; Bai, Y.; Lederkremer, R.
M. One-step Syntheses of 1,2,3,5,6-Penta-O-benzoyl-
a,b-D-galactofuranose and
1,2,3,5-Tetra-O-benzoyl- ,b- -arabinofuranose. Carbohydrate Chemistry: Proven
a
D
Methods; Paul Kovac, Ed.; CRC Press: Boca Raton, 2011; Vol. 1, 231–238.
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