Synthesis and evaluation of 1,2-trans alkyl galactofuranoside mimetics as mycobacteriostatic agents

Article abstract of DOI:10.1039/c5ob00296f

The simple octyl β-d-galactofuranoside was previously described as a good bacteriostatic agent against Mycobacterium smegmatis, a non-pathogenic model of M. tuberculosis. In order to decipher its mechanism of action, STD NMR on whole M. smegmatis cells wa

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ARTDIOCI: 1L0.1E039/TC5YOB0P02E96F
Synthesis and evaluation of 1,2-trans alkyl galactofuranoside mimetics
as mycobacteriostatic agents.
Rémy Dureau,a,c Maxime Gicquel,a,c Isabelle Artur,a,c Jean-Paul Guégan,a,c Bertrand Carboni,b,c Vincent
Ferrières,a,c Fabienne Berrée*b,c and Laurent Legentil*a,c
5
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX
DOI: 10.1039/b000000x
The simple octyl β-
D-galactofuranoside was previously described as good bacteriostatic agent against
Mycobacterium smegmatis, a non-pathogenic model of M. tuberculosis. In order to decipher its
10 mechanism of action, STD NMR on whole M. smegmatis cells was implemented. It outlined the crucial
role of the alkyl chain and the possibility of modulation on the furanosyl entity. From there, 16 new alkyl
furanosides were synthesized in order to optimize the mycobacteriostatic activity. They all present the
pending alkyl chain in a 1,2-trans configuration relative to the sugar ring. Three families were studied,
that differ by the substituent on the primary position of the galactofuranose ring, the series or the pending
15 alkyl chain. Four of these neofuranosides showed growth inhibition inferior to the parent octyl β-
D-
galactofuranoside. Double alkyl chains at C-1 and polar substituent on the primary position of the
furanoside significantly favored the activity. Finally, a mixed biantennary alkyl/aryl β-D-
galactofuranoside exhibited the best growth inhibition concentration at 90 µM.
6
of polysaccharides named arabinogalactanes.5, This structure
Introduction
50 incorporates in particular -galactofuranose -Galf),
D
(D
20 Tuberculosis is a medical, social, and economic disaster of
immense magnitude that occurs over the world, reaching a
dramatic level of 9 million people infected and 1.5 million deaths
each year.1 This deadly infection is difficult to cure and doing so
successfully requires long treatment periods with multiple
25 antibiotics.2 Recent first-line drugs against tuberculosis include
ethambutol and isoniazid in association with rifampicin and
pyrazinamid. Such Directly Observed Treatment, Short course
therapies (DOTS) present multiple shortcomings, like resistance
and side-effects.3 Therefore novel therapeutic approaches,
30 particularly those aimed at exploring new horizons for the
development of efficient anti-tuberculosis molecules, are
required. The use of poly- and monosaccharides with bactericidal
or bacteriostatic activities is nowadays gaining momentum
regarding to their natural distribution, in particular in crucial
35 cellular architecture of pathogenic microorganisms.4 For
example, the cell wall of Mycobacterium tuberculosis, the
bacteria responsible for tuberculosis, contains a complex mixture
thermodynamically less stable than its pyranose counterparts and
exogenous in mammals. In the light of the crucial role played by
such galactofuranosyl-containing conjugates, molecules that are
able to act on their biosynthesis, catabolism or degradation will
55 certainly interfere with the proliferation, virulence and even
survival of the corresponding cell. Such molecules will thus have
all the characteristic of a therapeutic agent directed towards Galf-
presenting cells with less toxicity toward other organisms.7
Different families of carbohydrate derivatives have been
60 already screened against strains of mycobacteria. For example,
uridine diphosphate galactofuranoses modified at the primary
position (C-6) of Galf were able to inhibit M. tuberculosis
growth.8 However their poor availability and low stability limited
their therapeutic potential. Another family was based on alkyl D-
65 arabinofuranosides. Such alkyl furanosides are able to inhibit the
growth of different strains of mycobacteria (M. smegmatis, M.
bovis, M. tuberculosis) and even to destroy it at concentrations
around micromolar.9-17 A model proposed by Sucheck et al.
hypothesized a specific recognition of the alkyl arabinofuranoside
70 motif by mycolyl transferases.13 It is worth noting that such
transferase inhibition is the key mechanism linked with the action
of ethambutol. Finally, a last class of molecules was designed on
the alkyl galactofuranoside model. The most promising results
described so far concerned a biantennary thiogalactofuranose
75 developed by von Iztein et al.18 In our laboratory, we conceived a
a Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 11
40 Allée de Beaulieu, CS 50837, 35708 Rennes Cedex 7, France. E-mail :
laurent.legentil@ensc-rennes.fr
b Institut des Sciences Chimiques de Rennes, UMR 6226
CNRS−Université de Rennes1, Avenue du Général Leclerc, CS 74205,
35042 Rennes Cedex, France. E-mail : fabienne.berree@univ-rennes1.fr
45 c Université européenne de Bretagne, France.
† Electronic Supplementary Information (ESI) available: STD NMR
1
simpler version, the octyl β-D-galactofuranoside 1 (Fig. 1) that is
parameter, STD spectrum of 1, 18 and n-octanol with M. smegmatis, H
and 13C NMR spectra. See DOI: 10.1039/b000000x/
able to inhibit the proliferation of M. smegmatis,
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Fig. 1 Targeted alkyl furanosides 2-17
the non pathogenic analogs of M. tuberculosis at a concentration
of 0.86 mM. Furthermore a bactericidal effect was observed
However the exact biological target of our galactofuranolipid is
yet unknown. Consequently the STD NMR was here performed
5
when it was embedded into a polymeric matrix based on 40 on the whole cell of M. smegmatis. Using this technique, we
PBAT/sodium caseinate.19, 20
compared the interaction profile of 1, its octyl galactopyranoside
counterparts 18 and n-octanol (Fig. 2 and supplementary
The mechanism of action associated with such
galactofuranolipids remains unclear and it is of importance to
decipher structure-activity relationships. To do so, we first
information). All compounds were used at a concentration of 5
mM in D2O. This concentration was higher than growth
10 compared the affinity of both octyl β-
D-galactofuranoside 1 and 45 inhibition value of 18 but lower that the CMC of each molecules
its octyl pyranoside counterpart with the microorganism’s surface
using Saturated Transfer Difference (STD) NMR technique on
whole cell. This preliminary experiment confirmed the
importance of the nature and length of the lipid chain but also
(6.1 mM for 1 and 16 mM for 18) in order to avoid again any
surfactant effect. When incubated with M. smegmatis cell, a
strong STD effect was observed at the extremity of the octyl
chain of 1. The percentage of STD effect decreased when moving
15 pointed out the weak interaction of the sugar with the cell 50 toward the furanose. There was also some detectable effect on the
membrane and so the possibility for modulation.
furanoside ring. The same profile was found for the octyl
pyranoside 18 and octanol. For the latter one, the STD effect was
identical along the alkyl chain.
In this context, a wider range of glycofuranosides bearing an
alkyl chain at the anomeric position in a 1,2-trans configuration
was synthesized. To tune the lipophilic nature of the alkyl
From these results, it first appeared that the alkyl chain on the
20 furanoside scaffold, three modulations were introduced (Fig. 1): 55 sugar played a crucial role on the activity, thus corroborating
i) substitution of the hydroxyl group at primary position (A-
family); ii) modification of the osidic series (B-family) and iii)
doubling of the octyl chain at the anomeric position (C-family).
The resulting compounds were eventually evaluated against their
25 inhibition of M. smegmatis growth.
previous results on such galactofuranolipids. Mycobacteria
present a unique cell surface made of mycolic acids that are
grafted on the arabinogalactan. This highly hydrophobic cell wall
Results and discussion
STD NMR experiment
We first investigated the action mechanism of octyl β-D-
galactofuranoside 1 as mycobacteriostastic. Compound 1 was
30 described as a mycobacteriostatic agent at a concentration of 0.86
mM.19 This value is far below its Critical Micellar Concentration
(CMC) that reaches 6.1 mM.21 Consequently, 1 is unable to form
some micelles in the considered inhibitory concentration and we
can rule out a possible surfactant effect as action mechanism. It is
35 possible nowadays to map the part of the drug specifically
involved in the interaction with the targeted receptor thanks to
60 Fig. 2 Quantification of molecular interactions of 1, 18 and octanol
with M. smegmatis by STD NMR.
23
Saturated Transfer Difference (STD) NMR technique.22,
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allows the bacteria to reduce its sensitivity against antibiotics and
6-amido. They can be easily introduced thanks to selective
the recognition by the immune cells.24 It can nevertheless interact
with other lipids through weak van der Walls interactions. We
can subsequently hypothesize that the alkyl chain strongly
nucleophilic attacks of the corresponding nucleophiles on
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position 6 of the cyclic sulfate 19 (Scheme 1). Compound 19 was
DOI: 10.1039/C5OB00296F
synthesized from octyl β-D-galactofuranoside according to
5
contributes to the interactions of the glycolipid with the cell 35 literature procedure.28 Ring-opening by tetrabutylammonium
membrane.
fluoride (TBAF), followed by the hydrolysis of the resulting
sulfate, led to the intermediate 20. In a similar way, 21 was
prepared from 19 using sodium azide in dimethylformamide. Its
subsequent palladium-catalyzed hydrogenolysis gave the amine
On the other hand, such experiment did not allow concluding
on the importance of the furanoside ring as the STD values on the
polar ring were low and no difference occurred between
10 pyranoside and furanoside. If the nature of the sugar moiety did 40 22 in a moderate yield. It can be purified by column
not reduce the measured affinity, we can therefore suggest that
modification on the carbohydrate scaffold should not deter the
interaction between the cell membrane and the glycolipids.
Interestingly, previous screening on eukaryote parasites of the
chromatography on silica gel or directly converted to N,O-diacyl
derivatives 23, 24, and 25 by action of acetyl chloride, benzoyl
chloride or valeroyl chloride, respectively, in presence of DMAP.
Finally, all the ester groups on compounds 20-25 were cleaved
15 Leishmania genus concluded on the importance of the substituent 45 under basic conditions to give desired products 2-7. All resulting
on the galactofuranoside scaffold to measure some growth
inhibition.25 In this context, and in an attempt to improve the
biological activity of the parent furanolipid, we decided to
modulate the lipophilicity of the alkyl chain and the polarity of
20 the sugar head.
compounds were obtained as pure 1,2-trans anomers as
confirmed by the value of the coupling constant between H-1 and
H-2 (J1,2 < 2 Hz).
In order to investigate the importance of the D-galactofuranose
50 scaffold, other series presenting a common skeleton with Galf
were also sought. The more hydrosoluble and pH-sensitive octyl-
Synthesis
D-galactofuranoside uronic acid (Octyl D-GalfA) 8 was obtained
5-Membered ring hexofuranoses generally tend to isomerise into
6-membered one, the most thermodynamically stable form. It is
thus critical to first lock the ring size and then modulate the
25 functional groups on the scaffold. To access to the A-family, we
according to reported furanosylation strategy of octanol in
presence of calcium chloride.22 The same procedure was
55 implemented to access to the octyl (methyl-β-
galactofuranosid)uronate using (methyl-β-
D
-
-
9
D
started from the known octyl β-D
-galactofuranoside 126, 27 whose
galactopyranoside)uronate 2629 (Scheme 2). The resulting uronate
9 was obtained as a mixture of anomers with a slight excess
towards the β-one. The targeted anomer was separated from the
60 α-isomer by purification on C18-grafted silica column. As for the
C-6 position could be tuned and whose anomeric configuration
was already installed, thus avoiding complex purification process.
Four functional groups were envisioned at the primary position
30 of the galactofuranose, the 6-fluoro, 6-azido, 6-amino and three
Scheme 1 Synthesis of octyl galactofuranosides of A-family 2-7. Reaction conditions: i) a. TBAF, THF, r.t., 1 h, b. H2SO4, H2O, THF, r.t., 30
min., 80% over 2 steps; ii) MeONa, MeOH, r.t., 12 h, 43% for 2, 86% for 3, 40% for 4, 61% for 5, 64% for 6, 89% for 7; iii) a. NaN3, DMF, r.t.,
65 24 h, b. H2SO4, H2O, THF, r.t., 30 min., 87% over 2 steps; iv) Pd(OAc)2, H2, THF, 3 days, 38%; v) a. Pd(OAc)2, H2, THF, 2 days, b. RCOCl,
DMAP, CH2Cl2, 2 h, 48% for 23, 41% for 24, 78% for 25 over 2 steps.
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OC8H17
i)
O
HO
C8H17OH
Cl
OC8H17
32
31
OC8H17
HO
OH
OH
HO
ii)
OC8H17
33
34
O
HO
OH
OH
HO
iii)
O
33
35
OR
OH
BnO
O
O
BnO
v)
iv)
36
37 R = H
vi)
38 R = C8H17
Scheme 3 Synthesis of the acceptors 32, 34 and 38. Reaction
35 conditions: i) C8H17OH, Na, toluene, r.t., 24 h, 41%; ii) a. NaH,
DMF, 50 °C, 15 min. b. TBAI, C8H17Br, DMF, 90 °C, 20 h, 52%; iii)
acetone, pTSA, MgSO4, r.t., 5 days, 74%; iv) NaH, benzylbromide,
THF, 70 °C, 15 h, 95%; v) H2SO4, MeOH, 70 °C, 4 h, 81%; vi)
NaH, TBAI, C8H17Br, DMF, 50 °C, 48 h, 70%.
Scheme 2 Synthesis of furanolipids from B-family 9-13. Reaction
conditions: i) C8H17OH, FeCl3, CaCl2, r.t., 24 h, 32% (α/β 2:3); ii) a.
C8H17OH, BF3.Et2O, CH2Cl2, RT, 8 h, b. MeONa, MeOH, r.t., 12 h,
12% for 10, 35% for 11, 44% for 12 over 2 steps; iii) a. C8H17OH,
CuCl2,ClCH2CH2Cl, r.t., 8 h, b. MeONa, MeOH, r.t., 12 h, 30% over
2 steps.
40 32, 34 and 38 were synthesized (Scheme 3). Glycerol derivative
32 was first prepared by reaction of epichlorohydrin with sodium
octanolate according to literature procedure.31 Dialkylation of 2-
(hydroxymethyl)-2-methyl-1,3-propanediol 33 with bromooctane
in presence of sodium hydride and tetrabutylammonium iodide
45 afforded the desired compound 34. On the other hand, the
protection of two alcohol functions of the triol 33 was easily
achieved by treatment with acetone in presence of pTSA leading
to the acetal 35. After benzylation with benzylbromide in the
presence of sodium hydride, the ketal moiety was hydrolyzed by
50 treatment with sulfuric acid in methanol. Monoalkylation of diol
37 was then accomplished in good yield using conditions
identical to those employed for the synthesis of 34.32
5
L-arabinose (
L-Ara), and L- and D-fucose (L- and D-Fuc) series, a
two-step strategy starting from the corresponding per-O-acetyl
10 furanose 27-29, respectively, was used. Such activated furanoses
were easily obtained from the parent sugars as described
previously.29 Glycosylation of octanol by 27, 28 or 29, in
presence of trifluoroboron etherate complex, generated again the
1,2-trans anomers as the major isomers. They were purified first
15 to remove the 1,2-cis anomer before subsequent
transesterification to give 10, 11 or 12, respectively.
Next, glycosylation of alcohols 32, 34 and 38 with 2,3,5,6-
tetra-O-acyl β-thiogalactofuranoside 3933 in presence of silver
55 triflate and N-iodosuccinimide gave the corresponding
intermediates 40, 41 and 42, respectively (Scheme 4).34 If the
biantennary galactofuranosides 41 and 42 were obtained as a
mixture of anomers, respectively α/β = 1:4 and 1:19, 40 was only
isolated as a pure β-anomer. Acyl groups were then removed
60 under basic conditions to give final products 14-16. Due to the
presence of an asymmetric carbon on the alkyl chain, 16 was
obtained as a complex mixture. Finally, debenzylation of 16 by
hydrogenolysis gave 17 as a non-separable diasteromeric mixture
but with 1,2-trans configuration at the anomeric carbon.
We previously described the formation of the oxazoline
derivative of 2-acetamido-2-deoxy-
D-galactofuranose
(D-
GalfNHAc) 30 thanks to the acetylation of per-O-silylated
20 GalfNHAc in presence of acetic anhydride and a large excess of
p-toluenesulfonic acid (pTSA).29 Such oxazoline could
nevertheless undergo nucleophilic attack by methanol to give
selectively the methyl β-D-GalfNHAc in excellent yield.
Unfortunately no reaction occurred when using octanol as
25 nucleophile in presence of various Lewis acids like BF3.Et2O or
TMSOTf. Nevertheless, copper(II) chloride, a weak Lewis acid,
allowed obtaining octyl GalfNHAc as a mixture of anomers.30
The 1,2-trans anomer was the major product of the reaction.
Transesterification of the ester finally gave the targeted octyl β-
30 GalfNHAc 13 with 30% yield over two steps.
Four biantennary substituents were envisioned at the C-1
position of galactofuranose (C-family). For that, three acceptors
D-
65 Biological evaluation
The resulting library of alkyl furanosides was then evaluated for
their bacteriostatic properties against a mutated strain of M.
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Scheme 4 Access to biantennary galactofuranosides 14-17 (C-family). Reaction conditions: i) a. 32, 34 or 38, MS, AgOTf, NIS, CH2Cl2, r.t.,
5-48 h, 71% for 40, 91% for 41 (α/β 1:4), 32% for 42 (α/β 1:19); ii) MeONa, MeOH, r.t., 12 h, 96% for 14, 99% for 15, 87% for 16; iii) H2,
Pd/C, EtOH, r.t., 2 days, 70%.
5
smegmatis (mc2 155), one of the non-pathogenic model of
mycobacteria. The Minimum Inhibition Concentration (MIC)
and 2 mM. Four neoglycolipids exhibited MIC values below the
one found for the parent octyl β- -Galf 1. First, octyl 6-amino-
-GalfA 8, with polar and pH sensitive
D
responsible for 99% of bacteria growth inhibition was reported 35 Galf 4 and octyl β-
D
for each compound in Table 1. The determination of the MIC
substituent on the pending C-4 arm of the skeleton, exhibited
respectively MIC value of 0.3 and 0.16 mM (entries 4 and 8).
Secondly, biantennary derivatives 15 and 16 showed inhibition of
M. smegmatis growth at 0.5 and 0.09 mM, respectively (entries
10 values was based on a resazurin modified assay in which the deep
blue resazurin was oxidized into the fluorescent pink resorufine
in the presence of living bacteria.35 The aim of this study was to
confirm: i) the influence of the alkyl chain at the anomeric 40 15 and 16).
position (chain length, linear vs. split); to complete the study,
15 methyl and butyl galactofuranosides 43 and 4436 were also
evaluated, ii) the impact of various functions at C-6 on the
activity, iii) the impact of the cycle (furanoside vs. pyranoside);
It therefore appeared that the furanose form was essential for
the activity as the pyranoside analog 18 showed no bacteriostatic
activity. In addition, no or low activity was measured with most
compounds from B-family (10-13). There was so a strong impact
octyl galactopyranoside 18 was thus included in the evaluation 45 of the considered series on the activity (Fucf, Araf, ester from
and iv) the importance of the nature and configuration of the
20 carbohydrate (Galf vs. others, vs. ). Ethambutol (Eth), a
GalfA vs. Galf). The lack of inhibitory activity of methyl and
butyl Galf, 43 and 44, confirmed also that a minimum chain
length was compulsory to measure any inhibition. The doubling
of the alkyl chain had nevertheless a medium effect. Furanoside
D
L
known antituberculosis molecule, was used as positive control.
The compiled results showed no inhibition for octanol (entry
21), 6-acetamido-Galf 5 (entry 5),
L
-Fucf 12 (entry 12), 50 14, the O-glycoside analog of von Iztein’s best inhibitor18
GalfNHAc 13 (entry 13) and Galf pending with branched alcohol
25 17 (entry 17) or with short chains 43 and 44 (entries 19 and 20) as
well as for octyl pyranoside 18 (entry 18). However, inhibitory
values were measured when the microorganism was incubated
surprisingly showed poor activity. It might be linked with lower
stability of O-glycosides when compared with S-glycosides.
However when the split chain was separated from the sugar by
one methyl, the inhibition increased. The best activity was found
55 for 16 with an aromatic group on one of the pendant arm instead
of the chain. In addition, structural modulations at C-6 position
greatly influenced the biological activity. Indeed compounds 5
(6-NHAc) showed no activity while decreasing MIC values were
with the other alkyl glycosides that derived from octyl
D-
galactofuranose 1 (A-Family, entries 2-4, 6 and 7), that shared
30 common structural characteristics with 1 (B-Family, entries 8-11)
or Galf with biantennary alkyl chain at the anomeric position (C-
Family, entries 14-16). Their MIC were found to be between 0.1
found for furanosides 6 (6-NHBz), 3 (6-N3), 9 (methyl
D-GalfA),
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galactofuranose moiety or a biantennary alkyl chain at the
anomeric position. The non symmetrical biantennary compound
16 with octyl and benzyl group on the bis(hydroxymethyl) linker
was found to inhibit the growth of M. smegmatis at 90 µM. Even
30 if these values were at least four times higher than the one found
with ethambutol, such family of molecules showed up to ten
times better inhibition than the parent octyl Galf, and was
described as innocuous towards other microorganisms or even
macrophages, thus increasing their associated therapeutic index.25
35 First attempt to better understand their mechanism of action was
achieved by STD NMR experiments that showed a strong affinity
between the alkyl chain and the cell wall of mycobacteria. There
should be first an anchorage of the alkyl chain to the cell wall
followed by the recognition of the furanose by specific receptors.
40 Studies to confirm this second step are under investigation.
Table 1 Minimum Inhibition Concentration of tested alkyl furanosides
OR3
OH
HO
HO
OH
OH
O
O
O
HO
HO
OC8H17
OC8H17
R1
R2
OH
OH
1-11 13-17 43-44
;
;
12
18
MIC
(mM)
0.8
1.5
1.7
Entry
R1
R2
R3
Pduct
1
2
3
4
5
6
7
8
9
10
12
13
14
CH2OH
CH2F
CH2N3
CH2NH2
CH2NHAc OH
CH2NHBz OH
NH(CO)Bu OH
CO2H
CO2Me
H
-
OH
OH
OH
OH
C8H17
C8H17
C8H17
C8H17
C8H17
C8H17
C8H17
C8H17
C8H17
C8H17
-
1
2
3
4
5
6
7
8
9
10
12
13
14
0.3
> 1.5a
2.0
1.2
0.16
1.6
OH
OH
OH
-
Experimental section
1.7
> 1.8a
> 1.5a
All reactions were carried out in oven-dried glassware.
CH2OH NHAc
CH2OH
C8H17
Tetrahydrofuran
and
toluene
were
distilled
from
CH(CH2OC8H17
)
2
OH
1
0.5
sodium/benzophenone, dimethylformamide from CaH2, dried
45 MeOH was purchased sealed on molecular sieves.
Dichloromethane used was stabilized on amylene. Optical
rotations were measured at 20 °C on a Perkin-Elmer 341
polarimeter. NMR spectra were recorded at 300 or 400 MHz for
1H and 75 or 100 MHz for 13C. Chemical shifts are given in δ
50 units (ppm) and referenced to CDCl3 (7.26 ppm) or CD3OD (3,31
ppm). Coupling constants J were calculated in Hertz (Hz). High
Resolution Masses were measured by electrospray with a MS/MS
ZabSpec TOF Micromass using m-nitrobenzylic alcohol as a
matrix and accelerated caesium ions for ionization (Centre
55 Regional des Mesures Physiques de l’Ouest, Université de
Rennes 1). Compounds 8,27 19,28 21,28 26,29 32,31 3732 and 3933
were prepared according to reported procedures.
CH2CCH3(CH2OC8H17
)
2
15
16
17
CH2OH
CH2OH
CH2OH
OH
OH
OH
15
16
17
CH2CCH3(CH2OC8H17)(CH2OBn)
CH2CCH3(CH2OC8H17)(CH2OH)
0.09
> 2a
18
19
20
21
22
-
-
OH
OH
-
-
CH3
C4H9
-
18
43
44
> 2a
CH2OH
CH2OH
> 2.6a
> 2.1a
-
-
Octanol > 3.8a
-
-
Eth
0.02
a No measured inhibition in the concentration range.
2 (6-F), 7 (6-NHCOBu), 4 (6-NH2) and 8 ( -GalfA). We can so
D
hypothesize that increasing the hydrophobicity on the
carbohydrate side arm was detrimental to the activity but that
polar substituents like hydroxyl, acid or amine increased the
potency of the molecule. The same trend was observed when A-
family analogs were incubated in presence of Leishmania
donovani promastigote.25
5
Synthesis of the A-family
10
There is consequently a strong impact of both the nature of the
lipid chain at the anomeric centre and the substituent on the
furanose C-4 side arm on the development of the mycobacteria.
The biantennary molecule 16 was found to be the best growth
inhibitor found so far in this family of O-alkyl
n-Octyl
2,3-di-O-benzoyl-6-deoxy-6-fluoro-β-D-
60 galactofuranoside 20. To a solution of 1928 (0.15 g, 0.27 mmol)
in acetone (6 mL) was added a 1M solution of TBAF in THF (0.6
mL, 0.55 mmol) and the mixture was stirred at room temperature
for 1 h. After concentration, the crude oil was diluted with THF
(6 mL) before adding a solution of conc. H2SO4 (50 µL, 0.8
65 mmol), and water (10 µL). The reaction mixture was stirred at
room temperature for 15 min then neutralized with Et3N,
concentrated under reduced pressure and portioned between
AcOEt (50 mL), and brine (25 mL). The organic layer was
washed with a saturated aqueous NaHCO3 solution (3×25 mL)
70 and the aqueous layers extracted with AcOEt (2×5 mL). Finally,
the combined organic layers were dried over MgSO4, filtered and
concentrated under reduced pressure. Purification of the residue
by flash chromatography on silica gel (cyclohexane/AcOEt, 4:1)
afforded the desired product (0.104 g, 80%) as a colorless oil.
75 [α]D20= +23.5 (c 1.25 in CHCl3). δH (400 MHz, CDCl3) 8.09-8.03
15 galactofuranosides. Previously, we showed that such family of
galactofuranolipids was completely innocuous towards both soil
microorganism and human macrophages.19, 25 It confirmed their
potential as alternative of DOTS.
Conclusion
20 Two strategies were implemented in order to obtain a library of
16 furanolipids bearing one or two alkyl chains, in a 1,2-trans
configuration of the carbohydrate moiety. After incubation with
M. smegmatis, four of them revealed good inhibitory values
against the microorganism growth. The best molecules are all
25 derived from galactofuranose and bear either a polar group on the
This journal is © The Royal Society of Chemistry [year]
[journal], [year], [vol], 00–00 | 6

Page 7 of 13
Organic & Biomolecular Chemistry
(4H, m, Ar-H), 7.62-7.57 (2H, m, Ar-H), 7.49-7.44 (4H, m, Ar-
H), 5.59 (1H, ddd, J3,4 4.4, J3,2 1.2, J 0.8, 3-H), 5.50 (1H, d, J3,2 60 of H2 for 3 days then concentrated under reduced pressure. The
mixture was stirred at room temperature under a positive pressure
4
View Article Online
1.2, 2-H), 5.26 (1H, brs, 1-H), 4.72 (1H, ddd, J6a,F 47.2, J6a,6b 9.6,
J6a,5 5.6 Hz, 6a-H), 4.55 (1H, ddd, J6b,F 46.8, J6b,6a 9.6, J6b,5 5.2,
residue was redissolved with AcOEt (100DmOLI:)1,0t.h10en39w/Ca5sOheBd00w29it6hF
saturated aq NaHCO3 solution (3 × 50 mL) and brine (50 mL).
The combined organic layers were dried over MgSO4, filtered
and concentrated under reduced pressure. Purification of the
2
3
5
6b-H), 4.39-4.29 (2H, m, 4-H, 5-H), 3.73 (1H, dt, J 9.6, J 6.8,
OCH2CH2), 3.53 (1H, dt, 2J 9.6, 3J 6.4, OCH2CH2), 2.65 (1H, d, J
8.4, OH), 1.68-1.59 (2H, m, OCH2CH2), 1.42-1.24 [10H, m, 65 residue by flash chromatography on silica gel (CH2Cl2/MeOH,
3
(CH2)5], 0.86 (3H, t, J 7.2, CH3). δC (100 MHz, CDCl3), 166.1,
165.3 (COPh), 133.6, 129.9, 129.8, 129.1, 128.6, 128.5 (CAr),
4:1) afforded the desired product (0.36 g, 38%) as a colorless oil.
[α]D20= -32 (c 1 in MeOH). δH (400 MHz, CDCl3) 8.07-8.03 (4H,
m, Ar-H), 7.59-7.53 (2H, m, Ar-H), 7.45-7.41 (4H, m, Ar-H),
5.57 (1H, dd, J3,4 4.8, J3,2 1.2, 3-H), 5.46 (1H, d, J2,3 1.2, 2-H),
10 105.7 (C-1), 83.6 (d, J6,F 170, C-6), 82.3 (d, J4,F 5, C-4), 81.3 (C-
3), 77.9 (C-2), 69.2 (d, J5,F 20, C-5), 67.7 (OCH2CH2), 31.8, 29.5,
29.3, 29.2, 26.1, 22.6 [(CH2)6], 14.1 (CH3). δF (376 MHz, 70 5.21 (1H, s, 1-H), 4.22 (1H, dd, J4,3 4.8, J4,5 3.2, 4-H), 4.11-4.08
2
3
CDCl3) -229. HRMS (ESI): calcd for C28H35FO7Na [M+Na]+
525.2264, found 525.2263.
(1H, m, 5-H), 3.71 (1H, dt, J 9.6, J 6.8, OCH2CH2), 3.49 (1H,
dt, 2J 9.6, 3J 6.8, OCH2CH2), 3.01 (2H, d, J5,6 6.0, 6-H), 1.65-1.57
3
15 n-Octyl 6-deoxy-6-fluoro-β-
D-galactofuranoside 2. To
a
(2H, m, OCH2CH2), 1.39-1.19 [10H, m, (CH2)5], 0.86 (3H, t, J
solution compound 20 (0.82 g, 1.63 mmol) in dry MeOH (10 mL)
6.8, CH3). δC (100 MHz, CDCl3) 166.0, 165.4 (CO), 133.5, 129.9,
was added a 30% wt. solution of sodium methoxide in MeOH (30 75 129.2, 128.5, 128.4, (CAr), 105.7 (C-1), 84.2 (C-4), 81.6 (C-2),
µL, 0.16 mmol). The mixture was stirred at room temperature
until no starting material was detected by TLC. Neutralization
20 was then carefully performed by adding Amberlite IR-120 (H+-
form). The resin was filtered off and the solvent removed under
78.0 (C-3), 70.6 (C-5), 67.6 (OCH2CH2), 45.0 (C-6), 31.8, 29.5,
29.4, 29.2, 26.1, 22.6 [(CH2)6], 14.1 (CH3). HRMS (ESI): calcd
for C28H37NNaO7 [M+Na]+ 522.2468, found 522.2470.
n-Octyl
6-amino-6-deoxy-β-
D-galactofuranoside
4.
reduced pressure. The resulting crude product was purified by 80 Deprotection proceeded according to the general procedure used
column chromatography on silica gel (CH2Cl2/MeOH 9:1) to give
the desired product (210 mg, 43%) as a yellow oil. [α]D20= -77.7
25 (c 1.2 in MeOH). δH (400 MHz, CD3OD) 4.85 (1H, d, 1-H), 4.47
(1H, ddd, J6a,F 46.8, J6a,6b 9.2, J6a,5 4.8, 6a-H), 4.42 (1H, ddd, J6b,F
for compound 2 starting from compound 22 (0.34 g, 0.68 mmol)
in dry MeOH (10 mL) with a 30% wt. solution of sodium
methoxide in MeOH (12.7 µL, 0.07 mmol). Purification of the
residue by column chromatography on silica gel (CH2Cl2/MeOH,
48.0, J6a,6b 9.2, J6b,5 6.8, 6b-H), 4.01 (1H, dd, J3,4 6.8, 3-H), 3.94- 85 9:1) afforded 4 (78.9 mg, 40%) as a white foam. [α]D20= -0.5 (c
4
3.90 (1H, m, 5-H), 3.93 (1H, dd, J2,3 4.0, J2,1 2.0, 2-H), 3.88 (1H,
dd, J4,3 6.8, J4,5 3.2, 4-H), 3.68 (1H, dt, 2J 9.6, 3J 6.8, OCH2CH2),
30 3.41 (1H, dt, 2J 9.6, 3J 6.8, OCH2CH2), 1.59-1.54 (2H, m,
OCH2CH2), 1.37-1.30 [10H, m, (CH2)5], 0.90 (3H, t, 3J 6.8, CH3).
1.3 in MeOH). δΗ (400 MHz, CD3OD) 4.82 (1H, dd, J 0.8, J1,2
0.8, 1-H), 3.93-3.90 (2H, m, 2-H, 3-H), 3.80-3.76 (1H, m, H-4),
2
3
3.67 (1H, dt, J 9.2, J 6.4, OCH2CH2), 3.63 (1H, ddd, J5,6a 6.8,
2
3
J5,6b 5.2, J5,4 4.0, 5-H), 3.40 (1H, dt, J 9.6, J 6.4, OCH2CH2),
δC (100 MHz, CD3OD) 109.5 (C-1), 85.2 (d, J6,F 168.5, C-6), 90 2.78 (1H, dd, J6a,6b 13.2, J6a,5 6.8, 6a-H), 2.74 (1H, dd, J6b,6a 13.2,
84.4 (C-2), 83.2 (d, J4-F 6.4, C-4), 78.4 (C-3), 70.2 (d, J5,F 19.7,
C-5), 69.0 (OCH2CH2), 33.0, 30.7, 30.5, 30.4, 27.3, 23.7
35 [(CH2)6], 14.5 (CH3). δF (376 MHz, CDCl3) -230. HRMS (ESI):
calcd for C14H27FNaO5 [M+Na]+ 317.1740, found 317.1739.
J6b,5 5.2, 6b-H), 1.60-1.53 (2H, m, OCH2CH2), 1.39-1.29 [10H,
m, (CH2)5], 0.88 (3H, t, J 6.8, CH3). δC (100 MHz, CD3OD)
109.4 (C-1), 85.4 (C-4), 83.7 (C-2), 79.0 (C-3), 72.9 (C-5), 69.0
(OCH2CH2), 45.7 (C-6), 33.0, 30.8, 30.6, 30.5, 27.3, 23.8
3. 95 [(CH2)6], 14.5 (CH3). HRMS (ESI): calcd for C14H29NNaO5
[M+Na]+ 314.1943, found 314.1943.
3
n-Octyl
6-azido-6-deoxy-β-D-galactofuranoside
Deprotection proceeded according to the general procedure used
for compound 2 starting from compound 21 (0.15 g, 0.28 mmol)
40 in dry MeOH (10 mL) with a 30% wt. solution of sodium
methoxide in MeOH (5 µL, 0.03 mmol). Purification of the
n-Octyl 6-acetamido-5-O-acetyl-2,3-di-O-benzoyl-6-deoxy-β-
D-galactofuranoside 23. To a solution of 21 (0.6 g, 1.14 mmol)
in dry THF (6 mL) was added Pd(OAc)2 (25 mg, 0.11 mmol).
residue by column chromatography on silica gel (CH2Cl2/MeOH, 100 The mixture was stirred at room temperature for 2 days under a
9:1) afforded the desired product (76.6 mg, 86%) as a colorless
oil. [α]D20= -48.7 (c 0.8 in MeOH). δH (400 MHz, CD3OD) 4.84
45 (1H, d, J1,2 2.0, 1-H), 3.97 (1H, dd, J3,4 6.4, J3,2 4.0, 3-H), 3.93
positive pressure of H2, then concentrated under reduced pressure.
The residue was redissolved in pyridine (10 mL), then DMAP (14
mg, 0.11 mmol) and acetyl chloride (0.24 mL, 3.42 mmol) were
added. The mixture was stirred at room temperature for 2h and
(1H, dd, J2,3 4.0, J2,1 2.0, 2-H), 3.83 (1H, dd, J4,5 3.2, 4-H), 3.88
2
(1H, ddd, J5,6a 7.6, J5,6b 4.8, J5,4 3.2, 5-H), 3.68 (1H, dt, J 9.6, 3J 105 concentrated under reduced pressure. The residue was redissolved
6.4, OCH2CH2), 3.41 (1H, dd, J6a,6b 13.2, J6a,5 7.6, 6a-H), 3.40
with AcOEt (50 mL), washed with saturated aqueous NaHCO3
solution (3×25 mL) and brine (25 mL). The combined organic
layers were dried over MgSO4, filtered and concentrated under
reduced pressure. Purification of the residue by flash
2
3
(1H, dt, J 9.6, J 6.4, OCH2CH2), 3.31 (1H, dd, J6b,6a 13.2, J6b,5
50 4.8, H-6b), 1.61-1.54 (2H, m, OCH2CH2), 1.39-1.29 [10H, m,
3
(CH2)5], 0.89 (3H, t, J 6.8, CH3). δC (100 MHz, CD3OD) 109.4
(C-1), 84.3 (C-4), 83.6 (C-2), 78.6 (C-3), 70.9 (C-5), 69.0 110 chromatography on silica gel (cyclohexane/AcOEt, 7:3) afforded
20
(OCH2CH2), 55.0 (C-6), 33.0, 30.8, 30.5, 27.3, 23.8 [(CH2)6],
14.5 (CH3). HRMS (ESI): calcd for C14H27N3NaO5 [M+Na]+
55 340.1843, found 340.1843.
the desired product (0.32 g, 48%) as a slightly yellow oil. [α]D =
-2.4 (c 1 in CHCl3). δH (400 MHz, CDCl3) 8.07-8.03 (4 H, m, Ar-
H), 7.60-7.56 (2 H, m, Ar-H), 7.47-7.42 (4 H, m, Ar-H), 6.09
(1H, t, JNH,6 5.6, NH), 5.44 (1H, d, J2,3 1.2, 2-H), 5.39 (1H, dt,
n-Octyl
6-amino-2,3-di-O-benzoyl-6-deoxy-β-D-
galactofuranoside 22. To a solution of 21 (1.0 g, 1.90 mmol) in 115 J5,6b 7.2, J4,5 3.6, J5,6a 3.6, 5-H), 5.37 (1H, dd, J3,4 5.2, J3,2 1.2, 3-
dry THF (20 mL) was added Pd(OAc)2 (43 mg, 0.19 mmol). The
H), 5.25 (1H, s, 1-H), 4.38 (1H, dd, J4,3 5.2, J4,5 3.6, 4-H), 3.79
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 7

Organic & Biomolecular Chemistry
Page 8 of 13
2
3
(1H, dd, J6a,6b 14.8, J6a,5 3.6, 6a-H), 3.74 (1H, dt, J 9.6, J 6.8,
(C-6), 31.8, 29.4, 29.2, 26.1, 22.6 [(CH2)6], 14.1 (CH3). HRMS
OCH2CH2), 3.56 (1H, dd, J6b,6a 14.8, J6b,5 7.2, 6b-H), 3.51 (1H, 60 (ESI): calcd for C42H45NNaO9 [M+Na]+ 730.2992, found
dt, J 9.6, J 6.8, OCH2CH2), 2.04 (3H, s, COCH3), 1.95 (3H, s,
COCH3), 1.67-1.59 (2H, m, OCH2CH2), 1.38-1.25 [10H, m,
View Article Online
DOI: 10.1039/C5OB00296F
2
3
730.2990.
n-Octyl
6-benzamido-6-deoxy-β-
D-galactofuranoside
6.
3
5
(CH2)5], 0.86 (3H, t, J 7.2, CH3). δC (100 MHz, CDCl3) 170.9,
Deprotection proceeded according to the general procedure used
170.1, 165.7, 165.3 (CO), 133.5, 129.9, 129.8, 129.1, 128.9,
for compound 2 starting from compound 24 (0.8 g, 1.13 mmol) in
128.5, 128.4 (CAr), 105.5 (C-1), 82.2 (C-4), 81.6 (C-2), 77.3 (C- 65 dry MeOH (10 mL) with a 30% wt. solution of sodium methoxide
3), 70.9 (C-5) 67.7 (OCH2CH2), 41.1 (C-6), 31.7, 29.4, 29.3, 29.2
[(CH2)6], 20.8 (COCH3), 14.0 (CH3). HRMS (ESI): calcd for
in MeOH (21.2 µL, 0.11 mmol). Purification of the residue by
column chromatography on silica gel (CH2Cl2/MeOH, 9:1)
afforded the desired product (0.29 g, 64%) as a white foam.
[α]D20= -41 (c 0.8 in MeOH). δH (400 MHz, CD3OD) 7.84-7.81
10 C32H41NNaO9 [M+Na]+ 606.2673, found 606.2675.
n-Octyl
6-acetamido-6-deoxy-β-
D-galactofuranoside
5.
Deprotection proceeded according to the general procedure used 70 (2H, m, Ar-H), 7.52-7.48 (1H, m, Ar-H), 7.44-7.40 (2H, m, Ar-
for compound 2 starting from compound 23 (0.32 g, 0.55 mmol)
in dry MeOH (10 mL) with a 30% wt. solution of sodium
15 methoxide in MeOH (10.3 µL, 0.05 mmol). Purification of the
residue by column chromatography on silica gel (CH2Cl2/MeOH,
H), 4.83 (1H, d, J1,2 2.0, 1-H), 4.05 (1H, dd, J3,4 6.4, J3,2 4.0, 3-
H), 3.97-3.94 (2H, m, 2-H, 5-H), 3.91 (1H, dd, J3,4 6.4, J4,5 3.2, 4-
2
3
H), 3.67 (1H, dt, J 9.2, J 6.4, OCH2CH2), 3.65 (1H, dd, J6a,6b
13.6, J6a,5 4.8, 6a-H), 3.65 (1H, dd, J6b,6a 13.6, J6b,5 7.2, 6b-H),
9:1) afforded the desired product (0.11 g, 61%) as a white foam. 75 3.39 (1H, dt, 2J 9.2, 3J 6.4, OCH2CH2), 1.58-1.51 (2H, m,
[α]D20= -59 (c 1 in MeOH). δH (400 MHz, CD3OD) 4.83 (1H, d,
J1,2 2.4, 1-H), 3.96 (1H, dd, J3,4 6.4, J3,2 4.0, 3-H), 3.91 (1H, dd,
20 J2,3 4.0, J2,1 2.4, 2-H), 3.80 (1H, dd, J4,3 6.4, J4,5 4.0, 4-H), 3.75
OCH2CH2), 1.33-1.26 [10H, m, (CH2)5], 0.87 (3H, t, 3J 6.8, CH3).
δC (100 MHz, CD3OD) 170.4 (CO), 135.5, 132.7, 129.5, 128.3
(C6H5), 109.4 (C-1), 85.0 (C-4), 83.4 (C-2), 78.7 (C-3), 70.0 (C-
5), 68.9 (OCH2CH2), 44.7 (C-6), 33.0, 30.7, 30.5, 30.4, 27.2, 23.7
2
(1H, ddd, J5,6b 7.6, J5,6a 4.8, J5,4 4.0, 5-H), 3.69 (1H, dt, J 9.6, 3J
6.8, OCH2CH2), 3.40 (1H, dt, 2J 9.6, 3J 6.8, OCH2CH2), 3.40 (1H, 80 [(CH2)6], 14.5 (CH3). HRMS (ESI): calcd for C21H33NNaO6
dd, J6a,6b 14.0, J6a,5 4.8, 6a-H), 3.23 (1H, dd, J6b,6a 14.0, J6b,5 7.6,
6b-H), 1.94 (3H, s, COCH3), 1.60-1.53 (2H, m, OCH2CH2), 1.37-
[M+Na]+ 418.2206, found 418.2206.
n-Octyl 2,3-di-O-benzoyl-6-deoxy-6-valeramido-5-O-valeroyl-
3
25 1.29 [10H, m, (CH2)5], 0.88 (3H, t, J 6.8, CH3). δC (100 MHz,
β-
D-galactofuranoside 25. To a solution of 21 (2.0 g, 3.80
CD3OD) 173.7 (CO), 109.4 (C-1), 84.9 (C-4), 83.5 (C-2), 78.8
mmol) in dry THF (20 mL) was added Pd(OAc)2 (85 mg, 0.38
(C-3), 70.2 (C-5), 69.0 (OCH2CH2), 44.1 (C-6), 33.1, 30.8, 30.6, 85 mmol). The mixture was stirred at room temperature for 2 days
30.5, 27.3, 23.8 [(CH2)6], 14.5 (CH3). HRMS (ESI): calcd for
C16H31NNaO6 [M+Na]+ 356.2049, found 356.2048.
under a positive pressure of H2, then concentrated under reduced
pressure. The residue was redissolved in pyridine (20 mL), then
DMAP (46 mg, 0.38 mmol) and valeroyl chloride (1.38 mL, 11.4
mmol) were added. The mixture was stirred at room temperature
30 n-Octyl
6-benzamido-2,3,5-tri-O-benzoyl-6-deoxy-β-D-
galactofuranoside 24. To a solution of 21 (0.96 g, 1.83 mmol) in
dry THF (10 mL) was added Pd(OAc)2 (40.4 mg, 0.18 mmol). 90 for 2 h and concentrated under reduced pressure. The residue was
The mixture was stirred at room temperature for 2 days under a
positive pressure of H2, then concentrated under reduced pressure.
35 The residue was redissolved in pyridine (10 mL), then DMAP
(22.3 mg, 0.18 mmol) and benzoyl chloride (0.53 mL, 4.57
redissolved with AcOEt (100 mL), washed with saturated
aqueous NaHCO3 solution (3×50 mL) and brine (50 mL). The
combined organic layers were dried over MgSO4, filtered and
concentrated under reduced pressure. Purification of the residue
mmol) were added. The mixture was stirred at room temperature 95 by flash chromatography on silica gel (cyclohexane/AcOEt, 7:3)
for 2 h and further concentrated under reduced pressure. The
residue was redissolved with AcOEt (100 mL), washed with
40 saturated aqueous NaHCO3 solution (3×50 mL) and brine (50
mL). The combined organic layers were dried over MgSO4,
afforded the desired product (1.99 g, 78%) as a slightly yellow
oil. [α]D20= -6.0 (c 1 in CHCl3). δH (400 MHz, CDCl3) 8.08-8.04
(4H, m, Ar-H), 7.61-7.57 (2H, m, H-Ar), 7.48-7.43 (4H, m, Ar-
H), 6.02 (1H, t, JNH,6 5.2, NH), 5.44 (1H, d, J2,3 1.2, 2-H), 5.25
filtered and concentrated under reduced pressure. Purification of 100 (1H, s, 1-H), 5.41-5.38 (2H, m, 3-H, 5-H), 4.38 (1H, dd, J4,3 5.2,
the residue by flash chromatography on silica gel
(cyclohexane/AcOEt, 4:1) afforded the desired product (0.52 g,
45 41%) as a colorless oil. [α]D20= -3.0 (c 1.2 in CHCl3). δΗ (400
MHz, CDCl3) 8.07-8.05 (4H, m, Ar-H), 7.96-7.94 (2H, m, Ar-H),
J4,5 3.6, 4-H), 3.80 (1H, ddd, J6a,6b 14.0, J6a,5 3.6, 6a-H), 3.74 (1H,
dt, 2J 9.6, 3J 6.8, OCH2 octyl), 3.57 (1H, ddd, J6b,6a 14.0, J6b,5 7.2,
3
2
6b-H), 3.51 (1H, dt, 2J 9.6, J 6.4, OCH2 octyl), 2.29 (2H, dt, J
3
3
7.6, J 3.6, CH2 valeroyl), 2.15 (2H, t, J 7.6, CH2 amide), 1.66-
7.76-7.74 (2H, m, Ar-H), 7.60-7.35 (10H, m, Ar-H), 7.27-7.23 105 1.51 (8H, m, OCH2CH2 octyl, CH2 valeroyl, CH2 valeroyl, CH2
(2H, m, Ar-H), 7.05 (1H, t, JNH,6 5.2, NH), 5.86 (1H,dt, J5,6b 7.2,
J5,6a 3.6, J5,4 3.6, 5-H), 5.55 (1H, dd, J3,4 5.2, J3,2 0.8, 3-H), 5.48
50 (1H, d, J2,3 0.8, 2-H), 5.36 (1H, s, 1-H), 4.58 (1H, dd, J4,3 5.2, J4,5
3.6, 4-H), 4.14 (1H, dd, J6a,6b 14.8, J6a,5 3.6, 6a-H), 3.95 (1H, dd,
amide), 1.34-1.20 [12H, m, CH2 amide, (CH2)5 octyl], 0.88 (3H, t,
3
3
3J 7.2, CH3), 0.86 (3H, t, J 6.8, CH3), 0.82 (3H, t, J 7.2, CH3).
δC (100 MHz, CDCl3) 173.8, 173.2, 165.7, 165.4 (CO), 133.5,
129.9, 129.8, 129.1, 129.0, 128.5, 128.4 (CAr), 105.5 (C-1), 82.3
J6b,6a 14.8, J6b,5 7.2, 6b-H), 3.79 (1H, dt, 2J 9.6, 3J 6.8, 110 (C-4), 81.7 (C-2), 77.3 (C-3), 70.6 (C-5), 67.7 (OCH2 octyl), 41.1
2
3
OCH2CH2), 3.56 (1H, dt, J 9.6, J 6.0, OCH2CH2), 1.70-1.62
(C-6), 36.5 (CH2 valeroyl), 33.9 (CH2 amide), 31.8, 29.5, 29.4,
29.3, 27.7, 26.9, 26.1, 22.6, 22.3, 22.1 [(CH2)6 octyl, (CH2)2
valeroyl, (CH2)2 amide], 14.1, 13.7, 13.6 (CH3). HRMS (ESI):
calcd for C38H53NNaO9 [M+Na]+ 690.3618, found 690.3613.
3
(2H, m, OCH2CH2), 1.42-1.25 [10H, m, (CH2)5], 0.87 (3H, t, J
55 6.4, CH3). δC (100 MHz, CDCl3) 167.4, 166.8, 165.9, 165.5 (CO),
134.2, 133.5, 133.4, 133.3, 131.4, 130.0, 129.9, 129.8, 129.2,
129.0, 128.9, 128.5, 128.4, 128.3, 126.9 (CAr), 105.6 (C-1), 82.8 115 n-Octyl 6-deoxy-6-pentanamido-β-D-galactofuranoside 7.
(C-4), 82.1 (C-2), 77.8 (C-3), 71.6 (C-5) 67.7 (OCH2CH2), 42.2
Deprotection proceeded according to the general procedure used
8
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This journal is © The Royal Society of Chemistry [year]

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Organic & Biomolecular Chemistry
for compound 2 starting from compound 25 (0.4 g, 0.60 mmol) in
mL) with a 30% wt. solution of sodium methoxide in MeOH
dry MeOH (10 mL) with a 30% wt. solution of sodium methoxide 60 (16.9 µL, 0.09 mmol). Purification of the residue by flash
in MeOH (11.2 µL, 0.06 mmol). Purification of the residue by
column chromatography on silica gel (CH2Cl2/MeOH, 9:1)
afforded the desired product (0.19 g, 89%) as a white foam.
[α]D20= -59 (c 0.9 in MeOH). δH (400 MHz, CD3OD) 4.82 (1H, d,
chromatography on silica gel (AcOEt/cycDloOhIe: x10a.n1e0,3V91ie/:Cw15)AOratiBfcfl0eo0rO2dn9eli6ndFe
the desired product (30.1 mg, 12%) as a colorless oil. [α]D20= -9
(c 1.1,in MeOH). δΗ (400 MHz, CD3OD) 4.80 (1H, d, J1,2 1.6, 1-
H), 3.90 (1H, dd, J2,3 3.6, J2,1 1.6, 2-H), 3.87 (1H, ddd, J4,3 6.4,
5
J1,2 2.0, 1-H), 3.96 (1H, dd, J3,4 6.4, J3,2 4.0, 3-H), 3.91 (1H, dd, 65 J4,5b 5.2, J4,5a 3.2, 4-H), 3.78 (1H, dd, J3,4 6.4, J3,2 3.6, 3-H), 3.70
2
3
J2,3 4.0, J1,2 2.0, 2-H), 3.79 (1H, dd, J4,3 6.4, J4,5 3.2, 4-H), 3.76
(1H, dd, J5a,5b 12.0, J5a,4 3.2, 5a-H), 3.66 (1H, dt, J 9.6, J 6.8,
OCH2CH2), 3.58 (1H, dd, J5b,5a 12.0, J5b,4 5.2, 5b-H), 3.36 (1H,
dt, 2J 9.6, 3J 6.8, OCH2CH2), 1.58-1.51 (2H, m, OCH2CH2), 1.34-
2
(1H, ddd, J5,6b 7.6, J5,6a 4.4, J5,4 3.2, 5-H), 3.69 (1H, dt, J 9.6, 3J
10 6.8, OCH2CH2), 3.41 (1H, dd, J6a,6b 14.0, J6a,5 4.4, 6a-H), 3.40
2
3
3
(1H, dt, J 9.6, J 6.8, OCH2CH2), 3.24 (1H, dd, J6b,6a 14.0, J6b,5
1.26 [10H, m, (CH2)5], 0.86 (3H, t, J 6.8, CH3). δC (100 MHz,
7.6, 6b-H), 2.19 (2H, m, CH2 amide), 1.61-1.53 (4H, m, CH2 70 CD3OD) 109.4 (C-1), 85.2 (C-4), 83.7 (C-2), 78.7 (C-3), 68.9
amide, OCH2CH2), 1.39-1.29 [12H, m, (CH2)5, CH2 amide], 0.92
(OCH2CH2), 63.0 (C-5), 33.1, 30.8, 30.6, 30.5, 27.3, 23.8
[(CH2)6], 14.5 (CH3). HRMS (ESI): calcd for C13H26NaO5
[M+Na]+ 285.1678, found 285.1677.
3
3
(3H, t, J 7.2, CH3), 0.88 (3H, t, J 7.2, CH3). δC (100 MHz,
15 CD3OD) 176.7 (CO), 109.4 (C-1), 84.9 (C-4), 83.6 (C-2), 78.8
(C-3), 70.3 (C-5), 69.0 (OCH2CH2), 43.9 (C-6), 36.9 (CH2
n-Octyl β-D
-fucofuranoside 11. To a solution of 2829 (0.2 g,
amide), 33.1, 30.8, 30.6, 30.5, 29.2, 27.3, 23.8, 23.4 [(CH2)6, 75 0.66 mmol) in dry CH2Cl2 (10 mL) was added octan-1-ol (0.16
(CH2)2 amide], 14.5, 14.1 (CH3). HRMS (ESI): calcd for
mL, 0.99 mmol) and BF3.Et2O (0.21 mL, 1.65 mmol) dropwise.
The mixture was stirred for 8 h at room temperature, then diluted
with CH2Cl2 (100 mL), washed with saturated aqueous NaHCO3
solution (3×50 mL) and brine (50 mL). The combined organic
80 layers were dried over MgSO4, filtered and concentrated under
reduced pressure. Subsequent deprotection proceeded according
to the general procedure used for compound 2 in dry MeOH (10
mL) with a 30% wt. solution of sodium methoxide in MeOH
(12.4 µL, 0.07 mmol). Purification of the residue by flash
85 chromatography on silica gel (AcOEt/cyclohexane, 1:1) afforded
the desired product (64 mg, 35%) as a colorless oil. Spectroscopic
data of the resulting compound were in accordance with the
literature.37
C19H37NNaO6 [M+Na]+ 398.2519, found 398.2518.
20 Synthesis of the B-family
n-Octyl β-D-(methyl-galactofuranosid) uronate 9. Compound 9
was obtained starting from 26 according to known procedure.27
To a suspension of uronate 26 (15 g, 72 mmol) in anhydrous THF
(150 mL) was added successively, at 0 °C and under vigorous
25 stirring, CaCl2 (9,24 g, 83,2 mmol), 1-octanol (19,7 ml,125
mmol) and, by portion, FeCl3 (40,5 g, 249,7 mmol). The resulting
mixture was allowed to stir at r.t. for 24 h. The solvent was
evaporated under reduced pressure and the resulting residue was
partitioned between ethyl acetate and 5% aqueous solution of
30 HCl. The resulting organic phase was washed with 5% aqueous
solution of HCl (10 times). The combined aqueous phases were
further extracted with ethyl acetate (3 times). The resulting
combined organic phase were finally washed with water and
brine, dried over MgSO4, and concentrated. The resulting mixture
35 was purified by column chromatography with CH2Cl2/MeOH
(99 :1) as eluent to give 9 as a mixture of anomers (7.44 g, 32%,
α/β 2:3). The separation was achieved by column
chromatography on C-18 grafted silica using H2O/CH3CN (7:3 to
1:1) as eluent to give 9β (4g, 17%). [α]D20= -68 (c 0.3 in MeOH).
40 δΗ (400 MHz, CD3OD) 4.83 (1H, d, J1,2 2.3, 1-H), 4.30 (1H, d,
J5,4 2.4, 5-H), 4.18 (1H, dd, J4,3 7.1, J4,5 2.4, 4-H), 4.10 (1H, dd,
J3,4 7.1, J3,2 4.5, 3-H), 3.93 (1H, dd, J2,1 2.3, J2,3 4.5, 2-H), 3.77
(3H, s, COCH3), 3.63 (1H, td, 2J 9.7, 3J 6.7, OCH2), 3.41 (1H, td,
n-Octyl L
-fucofuranoside 12. To a solution of 2929 (0.15 g, 0.45
90 mmol) in dry CH2Cl2 (10 mL) was added octan-1-ol (0.11 mL,
0.67 mmol) and BF3.Et2O (0.14 mL, 1.12 mmol) dropwise. The
mixture was stirred for 8 h at room temperature, then diluted with
CH2Cl2 (100 mL), washed with saturated aqueous NaHCO3
solution (3×50 mL) and brine (50 mL). The combined organic
95 layers were dried over MgSO4, filtered and concentrated under
reduced pressure. Subsequent deprotection proceeded according
to the general procedure used for compound 2 in dry MeOH (10
mL) with a 30% wt. solution of sodium methoxide in MeOH (8.4
µL, 0.04 mmol). Purification of the residue by flash
100 chromatography on silica gel (AcOEt/cyclohexane, 2:3) afforded
the desired product (54 mg, 44%) in anomeric mixture (α/β 8:1)
as a colorless oil. n-Octyl α-L-fucofuranoside (12α): δH (400
3
2J 9.7, J 6.5, OCH2), 1.61-1.52 (2H, m, OCH2CH2), 1.40-1.25
MHz, CD3OD) 4.79 (1H, d, J1,2 1.6, 1-H), 3.88 (1H, dd, J2,3 3.6,
J2,1 1.6, 2-H), 3.79 (1H, dd, J3,4 6.4, 3-H), 3.76 (1H, td, J5,6 6.4,
3
45 [10H, m, (CH2)5], 0.90 (3H, t, J 6.8, CH2CH3). δC (100 MHz,
2
3
CD3OD) 174.2 (CO), 109.4 (C-1), 84.7 (C-4), 83.4 (C-2), 77.7
(C-3), 70.7 (C-5), 69.2 (OCH2), 52.7 (COCH3), 33.0, 30.8, 30.5,
30.4, 27.3, 23.7 [(CH2)6], 14.4 (CH2CH3). HRMS (ESI): calcd for
C15H28NaO7 [M+Na]+ 343.1733, found 343.1736.
105 J5,4 4.8, 5-H), 3.66 (1H, dt, J 9.6, J 6.8, OCH2CH2), 3.63 (1H,
dd, J4,3 6.4, J4,5 4.8, 4-H), 3.37 (1H, dt, 2J 9.6, 3J 6.4, OCH2CH2),
1.57-1.50 (2H, m, OCH2CH2), 1.34-1.26 [10H, m, (CH2)5], 1.19
(3H, d, J6,5 6.4, H-6), 0.85 (3H, t, 3J 6.8, CH2CH3). δC (100 MHz,
CD3OD) 109.2 (C-1), 88.1 (C-4), 83.9 (C-2), 79.4 (C-3), 68.8
110 (OCH2CH2), 68.4 (C-5), 33.1, 30.8, 30.6, 30.5, 27.3, 23.8
50 n-Octyl α-L
-arabinofuranoside 10. To a solution of 2729 (0.3 g,
0.94 mmol) in dry CH2Cl2 (15 mL) was added octan-1-ol (0.22
mL, 1.41 mmol) and BF3.Et2O (0.3 mL, 2.35 mmol) dropwise.
The mixture was stirred for 5 h at room temperature, then diluted
with CH2Cl2 (100 mL), washed with saturated aqueous NaHCO3
55 solution (3×50 mL) and brine (50 mL). The combined organic
layers were dried over MgSO4, filtered and concentrated under
reduced pressure. Subsequent deprotection proceeded according
to the general procedure used for compound 2, in dry MeOH (10
[(CH2)6], 19.8 (C-6), 14.5 (CH2CH3). n-Octyl β-L-fucofuranoside
(12β): δH (400 MHz, CD3OD) 4.77 (1H, d, J1,2 4.0, 1-H), 3.89-
3.87 (1H, m, 2-H), 3.85-3.83 (1H, m, 3-H), 3.81-3.73 (1H, m,
OCH2CH2), 3.67-3.61 (1H, m, 5-H), 3.43-3.35 (2H, m, 4-H,
115 OCH2CH2), 1.57-1.50 (2H, m, OCH2CH2), 1.34-1.26 [10H, m,
3
(CH2)5], 1.12 (3H, d, J6,5 6.4, 6-H), 0.85 (3H, t, J 6.8, CH2CH3).
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 9

Organic & Biomolecular Chemistry
Page 10 of 13
δC (100 MHz, CD3OD) δ 102.7 (C-1), 87.5 (C-4), 79.4 (C-2),
mL), dried over MgSO4 and concentrated under vacuo. The
77.2 (C-3), 71.4 (C-5), 69.2 (OCH2CH2), 33.1, 30.8, 30.6, 30.5, 60 residue was purified by chromatography (cyclohexane/AcOEt
27.3, 23.8 [(CH2)6], 18.9 (C-6), 14.5 (CH2CH3). HRMS (ESI):
9:1) to give the title compound as a colorlesDsOoIi:l10(8.10003V9mie/Cwg5,AOr5tiB2cl0%e0O)2n.9li6nFe
3
calcd for C14H28O5Na [M+Na]+ 299.1834, found 299.1832.
δH (300 MHz, CDCl3) 3.57 (2H, d, J 5.8, CH2OH), 3.44-3.36
3
3
5
n-Octyl 2-acetamido-2-deoxy-β-
D-galactofuranoside 13. To a
(8H, m, CCH2, OCH2), 3.18 (1H, t, J 5.8, OH), 1.55 (4H, p, J
6.8, OCH2CH2), 1.44-1.24 [20H, m, (CH2)5], 0.90-0.86 (9H, m,
solution of 3029 (135 mg, 0.35 mmol) in dry 1,2-dichloroethane (1
mL) was added octan-1-ol (0.22 mL, 1.39 mmol) and CuCl2 (279 65 CCH3, CH2CH3). δC (75 MHz, CDCl3) 75.4, 71.7, 69.6
mg, 2.08 mmol). The mixture was refluxed for 8 h. The solution
was then allowed to cool to room temperature then vigorously
10 stirred with saturated aqueous NaHCO3 solution (1 mL). The
resulting biphasic solution was filtered on a pad of Celite and the
(CCH2,OCH2), 40.4 (CCH2), 31.8 (OCH2CH2), 29.5, 29.35, 29.2,
26.1, 22.6 [(CH2)5], 17.5 (CCH3), 14.0 (CH2CH3). HRMS (ESI):
calcd for C21H44O3Na [M+Na]+ 367.3188, found 367.3187.
3-(Benzyloxy)-2-methyl-2-[(octyloxy)methyl]propan-1-ol 38.
resulting cake extensively washed with ethyl acetate. The 70 To a solution of 37 (1 g, 4.8 mmol) in dry DMF (50 mL) was
subsequent filtrate was washed with water and brine. The organic
phase was dried over MgSO4, filtered and concentrated under
15 reduced pressure. The residue was purified by flash
chromatography on silica gel (AcOEt/cyclohexane, from 9:1 to
added NaH 60% in oil (0.58 g, 14.4 mmol). The mixture was
stirred at 50 °C for 15 minutes. A solution of TBAI (0.18 g, 0.48
mmol) and 1-bromooctane (2.76 g, 14.4 mmol.) in dry DMF (5
mL) was then slowly added. The reaction mixture was stirred at
3:2) to afford first n-octyl 2-acetamido-2-deoxy-3,5,6-tri-O- 75 50 °C for 2 days. The solvent was evaporated and the residue was
acetyl-β-
D
-galactofuranoside (48 mg, 30%) then the
dissolved in AcOEt (50 mL). The organic layer was washed with
water (3x20 mL), dried over MgSO4 and concentrated under
vacuo. The residue was purified by chromatography
(cyclohexane/AcOEt 8:2) to give compound 37 (800 mg, 70%) as
corresponding α-anomer (44 mg, 28%) both as colorless oils. β
20 anomer: δH (400 MHz, CDCl3) 5.99 (1H, d, JNH, 2 7.5, NH), 5.36
(1H, dt, J5,6b 7.1, J5,4 4.4, J5,6a 4.4, 5-H), 4.92 (1H, d, J1,2 1.2, 1-
H), 4.73 (1H, dd, J3,4 4.9, J3,2 2.3, 3-H), 4.37 (1H, ddd, J2,NH 7.5, 80 a colorless oil. δH (300 MHz, CDCl3) 7.41-7.28 (5H, m, Ar-H),
J2,1 1.2, J2,3 2.3, 2-H), 4.35 (1H, dd, J6a,6b 11.8, J6a,5 4.4, 6a-H),
4.53 (2H, d, 3J 1.9, OCH2Ph), 3.59 (2H, d, 3J 5.8, CH2OH), 3.49-
3
4.23 (1H, dd, J6b,6a 11.8, J5,6b 7.1, 6b-H), 4.17 (1H, dd, J4,3 4.9,
3.37 (6H, m, CCH2O, OCH2), 3.05 (1H, t, J 5.9, OH), 1.54 (2H,
2
25
J
4,5 4.4, 4-H), 3.61 (1H, dt, J 9.5, 3J 6.8, OCH2), 3.42 (1H, dt, 2J
p, 3J 6.7, OCH2CH2), 1.33-1.24 [10H, m, (CH2)5], 0.91-0.86 (6H,
m, CH3). δC (75 MHz, CDCl3) 138.4, 128.1, 127.3, 127.2 (CAr),
3
9.5, J 6.4, OCH2), 2.14 (3H, s, COCH3), 2.08 (3H, s, COCH3),
2.06 (3H, s, COCH3), 2.00 (3H, s, COCH3), 1.61-1.52 (2H, m, 85 75.4, 74.2, 73.3, 71.6, 68.9 (OCH2), 40.5 (CCH3), 31.7
OCH2CH2), 1.38-1.20 [10H, m, (CH2)5], 0.87 (3H, t, 3J 6.9,
CH2CH3). δC (101 MHz, CDCl3) 170.8 , 170.7, 170.2, 169.6
30 (CO), 106.8 (C-1), 80.0 (C-4), 78.2 (C-3), 70.2 (C-5), 68.0
(OCH2), 62.8 (C-6), 60.3 (C-2), 32.0, 29.6, 29.5, 29.4, 26.2
(OCH2CH2), 29.4, 29.2, 29.1, 26.0, 22.5 [(CH2)5], 17.4 (CCH3),
13.9 (CH2CH3). HRMS (ESI): calcd for C20H34O3Na [M+Na]+
345.2406, found 345.2409.
[(CH2)5], 23.4 (COCH3), 22.8 (OCH2CH2), 21.1, 20.9 (COCH3), 90 General Procedure for the synthesis of per-O-acetylated
14.2 (CH2CH3).
galactofuranosides 40-42
Deprotection of the β-anomer (19 mg, 0.04 mmol) proceeded
35 according to the general procedure used for compound 2 in dry
MeOH (1 mL) with a 30% wt. solution of sodium methoxide in
To a solution of 3933 (100 mg, 0.23 mmol) in dry DCM (10 mL)
were added successively alcohol 32, 34 or 38 (0.31 mmol) and
molecular sieves (500 mg). The solution, placed in the dark, was
MeOH (1 µL, 4 µmol). Evaporation of the solvent gave the 95 stirred at room temperature for 1 h and then cooled to -40 °C. N-
20
desired product 13 (14 mg, 100%) as a light brown solid. [α]D
=
iodosuccinimide (61 mg, 0.27 mmol) and AgOTf (18 mg, 0.07
mmol) were successively added to the solution and the reaction
mixture was then stirred at -40 °C. After 1.5 h the mixture was
warmed to room temperature and was kept under stirring between
+78 (c 0.85 in MeOH). δH (400 MHz, CD3OD+CDCl3) 4.86 (1H,
40 d, J1,2 1.5, 1-H), 4.12 (1H, dd, J2,3 3.1, J2,1 1.5, 2-H), 4.00 (1H,
dd, J3,4 5.5, J3,2 3.1, 3-H), 3.96 (1H, dd, J4,3 5.5, J4,5 2.6, 4-H),
3.76 (1H, td, J5,6 6.1, J5,4 2.6, 5-H), 3.68-3.61 (3H, m, 6-H, 100 5 h and 48 h. The reaction was then quenched by addition of Et3N
OCH2), 3.39 (1H, td, 2J 9.6, 3J 6.7, OCH2), 1.94 (3H, s, COCH3),
1.55 (2H, p, 3J 6.7, OCH2CH2), 1.33-1.21 [10H, m, (CH2)5], 0.85
(2 mL), filtered through celite and concentrated under vacuo. The
residue was purified by chromatography (cyclohexane/AcOEt
8:2) to give the corresponding compounds.
3
45 (3H, t, J 6.9, CH2CH3). δC (101 MHz, CD3OD+CDCl3) 172.2
(CO), 107.2 (C-1), 84.6 (C-4), 77.6 (C-3), 71.6 (C-5), 68.4
1,3-Bis(octyloxy)propanyl-2,3,5,6-tetra-O-acetyl-β-D-
(OCH2), 64.3 (C-6), 63.3 (C-2), 32.4, 30.0, 29.9, 29.8, 26.6, 23.1 105 galactofuranoside 40. After 5 h at room temperature and work-
[(CH2)6], 22.7 (COCH3), 14.3 (CH2CH3). HRMS (ESI): calcd for
up, the title compound was obtained as a colorless oil (104 mg,
71%) (β only). δH (400 MHz, CDCl3) 5.40 (1H, td, J5,6b 7.5, J5,6a
3.9, 5-H), 5.30 (1H, s, 1-H), 5.09 (1H, d, J2,3 2.0, 2-H), 4.97 (1H,
dd, J3,4 6.2, J3,2 2.0, 3-H), 4.37-4.32 (2H, m, 4-H, 6a-H), 4.21
C16H31NNaO6 [M+Na]+ 356.2049, found 356.2045.
50 Synthesis of the C-family
3
3
2-Methyl-3-(octyloxy)-2-[(octyloxy)methyl]propan-1-ol 34. To
a solution of 33 (1 g, 4.8 mmol) in dry DMF (50 mL) was added
NaH 60% in oil (0.76 g, 19 mmol). The mixture was stirred at 50
°C for 15 minutes. A solution of TBAI (0.18 g, 0.48 mmol) and
55 1-bromo-octane (4.6 g, 24 mmol) in dry DMF (5 mL) was then
added slowly. The reaction mixture was stirred at 90 °C for 20 h.
The solvent was evaporated and the residue was dissolved in
AcOEt (50 mL). The organic layer was washed with water (3x20
110 (1H, dd, J6b,6a 11.9, J6b,5 7.5, 6b-H), 3.96 [1H, tt, J 9.9, J 5.5,
CH(CH2OC8H17)2], 3.56-3.39 (8H, m, CHCH2, OCH2), 2.13 (3H,
s, COCH3), 2.09 (3H, s, COCH3), 2.07 (3H, s, COCH3), 2.05 (3H,
s, COCH3), 1.55-1.51 (4H, m, OCH2CH2), 1.31-1.27 [20H, m,
3
(CH2)5], 0.88 (6H, t, J 7.2, CH3). δC (100 MHz, CDCl3) 170.5,
115 170.1, 170.0, 169.5 (CO), 104.8 (C-1), 81.5 (C-2), 79.6 (C-4),
76.6 (C-3), 74.6 (CHCH2), 71.7, 71.7, 70.8, 70.7 (CHCH2,
10
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Journal Name, [year], [vol], 00–00
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Page 11 of 13
Organic & Biomolecular Chemistry
OCH2), 69.2 (C-5), 62.9 (C-6), 31.8 (OCH2CH2), 29.7, 29.6, 29.4,
3-(Benzyloxy)-2-methyl-2-[(octyloxy)methyl]propanyl-2,3,5,6-
-galactofuranoside 42. After 48 h at room
29.3, 26.1, 22.6 [(CH2)5], 20.8, 20.7, 20.6 (COCH3), 14.1 60 tetra-O-acetyl-
D
View Article Online
(CH2CH3). HRMS (ESI) calcd for C33H58NaO12 [M+Na]+:
temperature and work-up, the title compound was obtained as a
DOI: 10.1039/C5OB00296F
669.3826, found 669.3831.
1,3-Bis(octyloxy)propanyl
Deprotection of compound 40 (104 mg, 0.16 mmol) proceeded
colorless oil (71 mg, 32%) (α/β 5:95). Selected data for the α
anomer: δH (400 MHz, CDCl3) 5.85 (1H, d, J1,2 3.7, 1-H). β
anomer: δH (400 MHz, CDCl3) 7.35-7.27 (5H, m, Ar-H), 5.38
5
β-
D
-galactofuranoside
14.
according to the general procedure used for compound 2 in dry 65 (1H, td, J5,6b 7.2, J5,4 4.1, J5,6a 4.1, 5-H), 5.04 (1H, d, J2,3 1.8, 2-
MeOH (3 mL) with a 30% wt. solution of sodium methoxide in
H), 4.98 (1H, brs, 1-H), 4.96 (1H, dd, J3,4 5.8, J3,2 1.8, 3-H),
4.48 (2H, brs, CH2Ph), 4.29 (1H, dd, J6b,6a 11.8, J6a,5 4.1, 6a-H),
4.22-4.17 (2H, m, 6b-H, 4-H), 3.59 (1H, dd, 2J 9.2, 4J 3.9,
OCH2), 3.37-3.27 (7H, m, OCH2), 2.12 (3H, s, COCH3), 2.09
MeOH (30 µL, 0.016 mmol). The desired product was obtained
20
10 as a colorless oil (92 mg, 96%) (β only). [α]D = -51.85 (c 0.54
in MeOH). δH (400 MHz, CDCl3) 5.27 (1H, s, 1-H), 4.16 (1H,
3
3
brs, 4-H), 4.10 (1H, tt, J 9.9, J 5.5, CH(CH2OC8H17)2), 4.12- 70 (3H, s, COCH3), 2.06 (3H, s, COCH3), 2.02 (3H, d, 4J 2,
4.02 (2H, m, 3-H, 2-H), 3.96 (1H, ddd, J5,6b 6.1, J5,6a 4.1, J5,4 1.8,
5-H), 3.84 (1H, dd, J6a,6b 11.4, J6a,5 4.1, 6a-H), 3.75 (dd, 1H, J6b,6a
15 11.4, J6b,5 6.1, 6b-H), 3.46-3.38 (8H, m, CH2O), 3.18 (4H, brs,
OH), 1.59-1.52 (4H, m, OCH2CH2), 1.31-1.23 [20H, m, (CH2)5],
COCH3), 1.53-1.50 (2H, m, OCH2CH2), 1.31-1.25 [10H, m,
(CH2)5], 0.97 (3H, d, 4J 1.4, CCH3), 0.87 (3H, t, 3J 7.0, CH2CH3).
δC (100 MHz, CDCl3) 170.5, 170.1, 169.9, 169.6 (CO), 138.9,
128.3, 127.4, 127.2 (CAr), 105.5 (C-1), 81.0 (C-2), 79.9 (C-4),
0.88 (6H, t, 3J 6.9, CH3). δC NMR (100 MHz, CDCl3) δ 106.0 (C- 75 76.6 (C-3), 73.3, 73.1, 72.8, 71.6, 69.85 (OCH2), 69.3 (C-5), 62.8
1), 87.2 (C-4), 79.0 (C-2), 78.6 (C-3), 72.0 (CH), 71.8, 71.6
(OCH2), 71.1 (C-5), 70.7, 69.8 (OCH2), 64.2 (C-6), 31.8
20 (OCH2CH2), 29.5, 29.4, 29.3, 26.0, 22.6 [(CH2)5], 14.1 (CH3).
HRMS (ESI) calcd for C25H50O8Na [M+Na]+: 501.3403, found:
501.3402.
(C-6), 40.6 (CCH3), 31.9 (OCH2CH2), 29.6, 29.5, 29.3, 26.2, 22.6
[(CH2)5], 20.8, 20.7 (COCH3), 17.5 (CCH3), 14.1 (CH2CH3).
HRMS (ESI) calcd for C34H52O12Na [M+Na]+: 675.3356, found
675.3358.
80 3-(Benzyloxy)-2-methyl-2-[(octyloxy)methyl]propanyl-D-
2-Methyl-3-(octyloxy)-2-[(octyloxy)methyl]propanyl-2,3,5,6-
tetra-O-acetyl-D-galactofuranoside 41. After 5 h at room
25 temperature and work-up, the title compound was obtained as a
colorless oil (140 mg, 91%) (α/β 1:4). Selected data for the α
galactofuranoside 16. Deprotection of compound 42 (71 mg,
0.11 mmol) proceeded according to the general procedure used
for compound 2 in dry MeOH (2 mL) with a 30% wt. solution of
sodium methoxide in MeOH (20 µL, 0.011 mmol). The desired
anomer: δH (400 MHz, CDCl3) 5.12 (1H, d, J1,2 4.6, 1-H). β 85 product was obtained as a yellow oil (84 mg, 87%) (α/β = 5:95).
anomer: δH (400 MHz, CDCl3) 5.39 (1H, td, J5,6b 7.2, J5,4 4.0,
5,6a 4.0, 5-H), 5.05 (1H, d, J2,3 2.2, 2-H), 4.97 (1H, brs, 1-H),
30 4.96 (1H, dd, J3,4 5.4, J3,2 2.2, 3-H), 4.33 (1H, dd, J6a,6b 11.8,
J6a,5 4.0, 6a-H), 4.24-4.19 (2H, m, 6b-H, 4-H), 3.54 (1H, d, 2J 9.2,
Selected data for the α anomer: δH (400 MHz, CDCl3) 5.94 (1H,
d, J1,2 3.9, 1-H). β anomer: δH (400 MHz, CDCl3) 7.36-7.27 (5H,
m, Ar-H), 4.93 (1H, s, 1-H), 4.47 (2H, brs, CH2Ph), 4.02 (1H,
brs, 4-H), 3.99-3.95 (2H, m, 3-H, 2-H), 3.89 (1H, brs, 5-H), 3.78-
J
OCH2), 3.37-3.22 (9H, m, OCH2), 2.13 (3H, s, COCH3), 2.10 90 3.63 (3H, m, OCH2, 6a-H), 3.36-3.24 (7H, m, OCH2, 6b-H), 1.54-
(3H, s, COCH3), 2.07 (3H, s, COCH3), 2.05 (3H, s, COCH3),
1.47 (2H, m, OCH2CH2), 1.32-1.28 [10H, m, (CH2)5], 0.91 (3H,
4
3
1.54-1.49 (4H, m, OCH2CH2), 1.32-1.25 [20H, m, (CH2)5], 0.92
d, J 3.4, CCH3), 0.88 (3H, t, J 7, CH2CH3). δC (100 MHz,
CDCl3) 138.4, 128.3, 127.5, 127.45 (CAr), 108.0 (C-1), 87.2 (C-
4), 78.8, 78.6 (C-2, C-3), 73.4, 73.3, 71.9, 71.8 (OCH2), 70.9 (C-
3
35 (3H, s, CH3), 0.88 (6H, t, J 7.0, CH3). δC (100 MHz, CDCl3)
170.5, 170.1, 169.9, 169.6 (CO), 105.5 (C-1), 81.0 (C-2), 79.8
(C-4), 76.6 (C-3), 73.2, 73.1, 71.6, 69.9 (OCH2), 69.3 (C-5), 62.8 95 5), 70.6 (OCH2), 64.3 (C-6), 40.2 (CCH3), 31.8 (OCH2CH2),
(C-6), 40.5 (CCH3), 31.85 (OCH2CH2), 29.6, 29.4, 29.3, 26.2,
22.7 [(CH2)5], 20.8, 20.7, 20.6 (COCH3), 17.4 (CCH3), 14.1
40 (CH2CH3). HRMS (ESI) calcd for C35H62O12Na [M+Na]+:
697.4139, found 697.4143.
29.5, 29.4, 29.3, 26.1, 22.7 [(CH2)5], 17.9 (CCH3), 14.1
(CH2CH3). HRMS (ESI) calcd for C26H44O8Na [M+Na]+:
507.2934, found: 507.2931.
3-Hydroxy-2-methyl-2-[(octyloxy)methyl]propanyl-β-D-
2-Methyl-3-(octyloxy)-2-[(octyloxy)methyl]propanyl-
D
-
100 galactofuranoside 17. To a solution of 16 (19 mg, 0.04 mmol) in
ethanol (1 mL) was added palladium on activated charcoal (10%
Pd contents, 5 mg). The mixture was stirred for 2 days under
1atm of H2. Then, the solution was filtered on a pad of Celite and
the resulting cake extensively washed with ethanol. The
galactofuranoside 15 . Deprotection of compound 41 (140 mg,
0.2 mmol) proceeded according to the general procedure used for
45 compound 2 in dry MeOH (4 mL) with a 30% wt. solution of
sodium methoxide in MeOH (40 µL, 0.02 mmol). The desired
product was obtained as a yellow oil (100 mg, 99%) (α/β 1:4). 105 subsequent filtrate was concentrated under reduced pressure. The
Selected data for the α anomer: δH (400 MHz, CDCl3) 5.90 (1H,
d, J1,2 4.2, 1-H). β anomer: δH (400 MHz, CDCl3) δ 4.93 (1H, s,
50 1-H), 4.05-3.97 (3H, m, 4-H, 3-H, 2-H), 3.92 (1H, m, 5-H), 3.81-
3.60 (4H, m, OCH2, 6-H), 3.37-3.21 (8H, m, OCH2), 2.29 (4H,
residue was purified by flash chromatography on C-18 grafted
silica gel (H2O/CH3CN, 4:6) to afford 17 as a mixture of
diastereomers (10 mg, 70%) as a colorless oil (β only). δH (400
MHz, CD3OD) 4.83-4.81 (1H, m, 1-H), 4.00 (1H, dd, J3,4 6.0, J3,2
brs, OH), 1.56-1.49 (4H, m, OCH2CH2), 1.30-1.25 [20H, m, 110 3.4, 3-H), 3.98-3.89 (2H, m, 3-H, 2-H), 3.77-3.68 (1H, m, 5-H),
3
(CH2)5], 0.88 (3H, s, CCH3), 0.87 (6H, t, J 7, CH2CH3). δC (100
MHz, CDCl3) δ 107.9 (C-1), 88.1 (C-4), 78.7 (C-2, C-3), 73.5,
55 71.9, 71.8, 71.6 (OCH2), 71.0 (C-5), 70.8 (OCH2), 64.4 (C-6),
40.2 (CCH3), 31.8 (OCH2CH2), 29.6, 29.5, 29.4, 29.3, 26.1, 22.7
3.67-3.57 (3H, m, 6-H, CHOCH2), 3.48-3.44 (2H, m, CH2OH),
3.46-3.36 [2H, m, CH2(CH2)6CH3], 3.35-3.25 (3H, m, CH2OOct,
CHOCH2), 1.59-1.50 [2H, m, CH2(CH2)5CH3], 1.38-1.27 [10H,
m, (CH2)5CH3], 0.93-0.88 [6H, m, (CH2)5CH3, CCH3]. δC (100
[(CH2)5], 17.8 (CCH3), 14.1 (CH2CH3). HRMS (ESI) calcd for 115 MHz, CD3OD) 109.6 (C-1), 84.7, 84.5 (C-4), 83.1, 83.0 (C-2),
C27H54O8Na [M+Na]+: 529.3716, found: 529.3712.
78.9 (C-3), 75.0, 74.7 (CH2OOct), 72.7 (CH2(CH2)6CH3), 72.5
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Organic & Biomolecular Chemistry
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(C-5), 71.4 (CHOCH2), 66.7, 66.4 (CH2OH), 64.5 (C-6), 41.9,
55 7. F. Pan, M. Jackson, Y. Ma and M. McNeil, J. Bacteriol., 2001, 183,
41.8 (CCH3), 33.0, 30.7, 30.6, 30.4, 27.4, 23.7 [(CH2)6], 17.6
(CCH3), 14.4 (CH2CH3). HRMS (ESI) calcd for C19H38O8Na
[M+Na]+: 417.2464, found 417.2469.
3991-3998.
8. P. Peltier, M. Beláňová, P. Dianišková, R. Zhou, R. B. VZiehwenAgrt,icJl.e AOn. line
DOI: 10.1039/C5OB00296F
Pearcey, M. Joe, P. J. Brennan, C. Nugier-Chauvin, V. Ferrières, T.
L. Lowary, R. Daniellou and K. Mikušová, Chem. Biol., 2010, 17,
1356-1366.
5
Microtiter test based evaluation of Minimum Inhibitory
Concentration (MIC) against Mycobacterium smegmatis
60
9. C. A. Centrone and T. L. Lowary, Bioorg. Med. Chem., 2004, 12,
5495-5503.
Preparation of M. smegmatis cultures. A single colony of strain
mc2155 of M. smegmatis was grown in 25 mL Luria Bertani (LB)
broth containing kanamycin (50 µg/mL) for 24 h at 37 °C (180
10 rpm). A 1% inoculum from this culture was transferred into fresh
5 mL LB medium containing kanamycin (50 µg/mL) and
incubated overnight (37 °C, 180 rpm), giving. the desired M.
smegmatis suspension.
10. N. K. Khare, F. J. Duarte, R. C. Reynolds and J. A. Maddry,
ARKIVOC, 2013, 290-315.
65 11. A. K. Pathak, V. Pathak, M. Kulshrestha, D. Kinnaird, W. J. Suling,
S. S. Gurcha, G. S. Besra and R. C. Reynolds, Tetrahedron, 2003, 59,
10239-10248.
12. J. A. Maddry, N. Bansal, L. E. Bermudez, R. N. Comber, I. M. Orme,
W. J. Suling, L. N. Wilson and R. C. Reynolds, Bioorg. Med. Chem.
Preparation
of
different
concentrations
of
octyl
15 glycofuranosides. Different amounts of octyl glycofuranosides
were dissolved in LB broth containing kanamycine (50 µg/mL) in
order to obtain a total volume of 1.1 mL with the following
concentrations in furanosides: 0, 0.05, 0.1, 0.2, 0.3 and 0.4
mg/mL. Each tube was then supplemented with 10 µL of the M.
20 smegmatis culture. In parallel, an equal number of tubes without
inoculums was prepared to serve as blanks. All samples were
finally incubated for 3 days at 37 °C and 180 rpm.
Determination of MIC. A 30 µL aliquot from a 0.1% (w/v)
solution of resazurine prepared in sterile water was added to each
25 sample. After developing for 1 h at 37 °C and 180 rpm, each
sample (1 mL) was centrifuged (10000 rpm, 4 °C, 10 min). The
supernatant (200 µL) was then pipetted and added to identified
wells of a 96-well microplate, containing sterile water (0.2 mL).
The plate had a set of controls: a column with a broad-spectrum
30 antibiotic as positive control (ethambutol in serial dilution), a
column with all solutions with the exception of the test
compound, and a column with all solutions with the exception of
M. smegmatis. The absorbance of each well at 600 nm was then
measured in 96-wells-microtiter plate reader. The MIC of sample
35 without bacterial inoculum was then calculated as the
concentration where 99% of the bacteria growth is inhibited.
70
Lett., 1998, 8, 237-242.
13. A. K. Sanki, J. Boucau, P. Srivastava, S. S. Adams, D. R. Ronning
and S. J. Sucheck, Bioorg. Med. Chem., 2008, 16, 5672-5682.
14. B. K. Singh, A. K. Yadav, B. Kumar, A. Gaikwad, S. K. Sinha, V.
Chaturvedi and R. P. Tripathi, Carbohydr. Res., 2008, 343, 1153-
1162.
75
15. B. L. Wilkinson, H. Long, E. Sim and A. J. Fairbanks, Bioorg. Med.
Chem. Lett., 2008, 18, 6265-6267.
16. B. Ayers, H. Long, E. Sim, I. A. Smellie, B. L. Wilkinson and A. J.
Fairbanks, Carbohydr. Res., 2009, 344, 739-746.
80 17. K. Naresh, B. K. Bharati, P. G. Avaji, N. Jayaraman and D. Chatterji,
Org. Biomol. Chem., 2010, 8, 592-599.
18. C. B. Davis, R. D. Hartnell, P. D. Madge, D. J. Owen, R. J. Thomson,
A. K. J. Chong, R. L. Coppel and M. von Itzstein, Carbohydr. Res.,
2007, 342, 1773-1780.
85 19. L. Legentil, J.-L. Audic, R. Daniellou, C. Nugier-Chauvin and V.
Ferrières, Carbohydr. Res., 2011, 346, 1541-1545.
20. J.-L. Audic, L. Legentil, C. Nugier-Chauvin, V. Ferrières, M. Potel
and T. Roisnel, J. Mater. Chem., 2012, 47, 5806-5814.
21. J. W. Goodby, J. A. Haley, G. Mackenzie, M. J. Watson, D.
90
Plusquellec and V. Ferrières, J. Mater. Chem., 1995, 5, 2209-2220.
22. M. Mayer and B. Meyer, Angew. Chem. Int. Ed., 1999, 38, 1784-
1788.
Acknowledgements
We are grateful to Dr. K. Mikušová from Comenius University,
Bratislava for the gift of mc2155 strain of M. smegmatis. We
40 thank also UMR CNRS 6226 for financial supports.
23. B. Claasen, M. Axmann, R. Meinecke and B. Meyer, J. Am. Chem.
Soc., 2004, 127, 916-919.
95 24. J. A. Verschoor, M. S. Baird and J. Grooten, Prog. Lipid Res., 2012,
51, 325-339.
Notes and references
25. M. Suleman, J.-P. Gangneux, L. Legentil, S. Belaz, Y. Cabezas, C.
Manuel, R. Dureau, O. Sergent, A. Burel, F. Daligault, V. Ferrières
and F. Robert-Gangneux, Antimicrob. Agents Chemother., 2014, 58,
1. Global Tuberculosis report 2014, World Health Organization,
http://www.who.int/tb/publications/global_report/en/
January 2015).
(accessed
100
2156-2166.
26. V. Ferrières, J.-N. Bertho and D. Plusquellec, Tetrahedron Lett.,
1995, 36, 2749-2752.
45 2. J. B. Bass, Jr., L. S. Farer, P. C. Hopewell, R. O'Brien, R. F. Jacobs,
F. Ruben, D. E. Snider, Jr. and G. Thornton, Am. J. Respir. Crit. Care
Med., 1994, 149, 1359-1374.
27. V. Ferrières, J.-N. Bertho and D. Plusquellec, Carbohydr. Res., 1998,
311, 25-35.
3. A. Scorpio and Y. Zhang, Nat. Med., 1996, 2, 662-667.
4. P. Stallforth, B. Lepenies, A. Adibekian and P. H. Seeberger, J. Med.
105 28. R. Dureau, F. Robert-Gangneux, J.-P. Gangneux, C. Nugier-Chauvin,
L. Legentil, R. Daniellou and V. Ferrières, Carbohydr. Res., 2010,
345, 1299-1305.
50
Chem., 2009, 52, 5561-5577.
5. P. J. Brennan, Tuberculosis, 2003, 83, 91-97.
29. R. Dureau, L. Legentil, R. Daniellou and V. Ferrières, J. Org. Chem.,
2012, 77, 1301-1307.
6. T. L. Lowary, in Glycoscience: Chemistry and Chemical Biology,
eds. B. Fraser-Ried, K. Tatsuka and J. Thiem, Springer Verlag, Berlin
Heilderberg New York, 2001, vol. III, pp. 2005-2080.
12
|
Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 13 of 13
Organic & Biomolecular Chemistry
30. V. Subramanian, M. Moumé-Pymbock, T. Hu and D. Crich, J. Org.
Chem., 2011, 76, 3691-3709.
View Article Online
31. G. R. Bebernitz, J. G. Dain, R. O. Deems, D. A. Otero, W. R.
Simpson and R. J. Strohschein, J. Med. Chem., 2000, 44, 512-523.
32. M. Ouchi, Y. Inoue, K. Wada, S. Iketani, T. Hakushi and E. Weber,
J. Org. Chem., 1987, 52, 2420-2427.
DOI: 10.1039/C5OB00296F
5
33. M. Gelin, V. Ferrières and D. Plusquellec, Eur. J. Org. Chem., 2000,
1423-1431.
34. Y. Bai and T. L. Lowary, J. Org. Chem., 2006, 71, 9658-9671.
10 35. S. D. Sarker, L. Nahar and Y. Kumarasamy, Methods, 2007, 42, 321-
324.
36. L. Baldoni and C. Marino, J. Org. Chem., 2009, 74, 1994-2003.
37. R. Euzen, V. Ferrières and D. Plusquellec, J. Org. Chem., 2005, 70,
847-855.
15
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 13