Synthesis and structural analysis of a series of d-glucose derivatives as low molecular weight gelators

Article abstract of DOI:10.1016/j.carres.2008.12.006

Low molecular weight gelators are an interesting new type of compounds that are important in supramolecular chemistry and advanced materials. Previously, we had synthesized several acyl derivatives of methyl 4,6-O-benzylidene-α-d-glucopyranoside and found

Full text of DOI:10.1016/j.carres.2008.12.006

Carbohydrate Research 344 (2009) 417–425
Contents lists available at ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Synthesis and structural analysis of a series of D-glucose derivatives as low
molecular weight gelators
*
Sherwin Cheuk, Edwin D. Stevens, Guijun Wang
Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 10 October 2008
Received in revised form 27 November 2008
Accepted 2 December 2008
Available online 13 December 2008
Low molecular weight gelators are an interesting new type of compounds that are important in supramo-
lecular chemistry and advanced materials. Previously, we had synthesized several acyl derivatives of
methyl 4,6-O-benzylidene-a-D-glucopyranoside and found that a number of terminal acetylene-contain-
ing esters are good gelators. To understand the structure requirement of the acyl chains, we synthesized a
series of analogs containing different functional groups including aryl, alkenyl, and halogen derivatives.
X-ray crystal structures of a monoester and a diester derivative were also obtained to help understand the
relationship between structure and gelation. For good gelation properties, the carboxyl derivatives should
possess alkyl groups containing a terminal acetylene group and aryl derivatives.
Keywords:
D-Glucose
Hydrogelators
Organogelators
Self-assembly
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
drate-based hydrogelators have intrinsic chirality, which could
lend themselves to applications in ferroelectric liquid crystals or
Low molecular weight organogelators and hydrogelators are an
interesting new class of compounds that have drawn great atten-
tion over the past few decades.1–4 The gelation properties of these
compounds are determined by their structures and modes of self-
organization in various solvents. The driving forces for the forma-
tion of the physical gels are non-covalent intermolecular forces.
These include hydrogen bonding, electrostatic interactions, van
separation of biologically important agents such as proteins and
DNA. Furthermore, hydrogels formed by carbohydrate derivatives
are biocompatible. This is important for potential biomedical
applications.
Previously, we had synthesized several sugar derivatives and
found that short chain esters of methyl 4,6-O-benzylidene-a-D-
glucopyranoside are good gelators for hexane, ethanol, and an
der Waals interaction, and p–p stacking. The potential applications
ethanol–water mixture.46 These esters were synthesized by an
of these compounds in various fields have also propelled their fur-
ther development. These include their uses in enzyme immobiliza-
tion,5 drug-delivery systems,6–9 and advanced nanomaterials.3,4,10–12
There is a great diversity among the structures of organogelators
and hydrogelators. Amino acids and carbohydrates are often used
as the building blocks for low molecular weight gelators. Many re-
search efforts have been devoted to the preparation and character-
ization of effective hydrogelators13–27 and to their potential
applications.28–32 Low molecular weight hydrogelators are particu-
larly interesting because they can form hydrogels that lend them-
selves to many applications. Among the different types of organo/
hydrogelators, carbohydrate-derived gelators are of particular
interest to us because of their unique nature. Sugar-based systems
have been used by many research groups in the preparation of low
molecular weight gelators.33–47 Sugars contain polar hydroxyl
groups that can be utilized as hydrogen bond donors or be func-
tionalized to form useful self-assembling aggregates. Carbohy-
acylation reaction of the sugar headgroup with a,x alkynyl acids.
Compounds 1–3 are representative structures of the three classes
of organo/hydrogelators we have synthesized. These compounds
contain a short alkynyl chain, which is 5-carbons in length. These
are effective gelators for the tested solvents including hexane, eth-
anol, and aqueous solutions. The 5–7 carbon monoalkynyl esters
are good hydrogelators. Several carbamoyl derivatives containing
5 or 7 carbon alkyl chains were also synthesized, and the monocar-
bamates are also excellent gelators.46
In addition to the short chain derivatives, we had also pre-
pared a series of long chain ester derivatives containing diacety-
lene functional groups and found that these compounds can
form gels in ethanol–water mixtures.47 To understand the struc-
tural requirements of the acyl chains for good gelators and gela-
tion properties of these simple carbohydrate derivatives, we
synthesized and characterized a series of additional compounds
containing different functional groups, including methacryloyl,
alkenyl, halogen, and aryl derivatives. Methacrylate-containing
gelators can be polymerized and lead to potentially new materi-
als.48–52
* Corresponding author. Tel.: +1 504 280 1258; fax: +1 504 280 6860.
E-mail addresses: gwang2@uno.edu, wangguij@yahoo.com (G. Wang).
0008-6215/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2008.12.006

418
S. Cheuk et al. / Carbohydrate Research 344 (2009) 417–425
O
O
Ph
Ph
O
O
Ph
O
O
O
O
O
HO
O
O
O
O
O
OH
O
OCH3
OCH3
O
OCH3
O
2
3
1
to form gels in the ethanol–water mixture. The dimethacrylate
11a did not form gels in the solvents tested. However, we were
able to obtain a single crystal X-ray structure of the dimethacrylate
(recrystallized from ethanol and acetone mixture) as shown in Fig-
ure 2. The two acyl chains are extending from the six-membered
ring and the phenyl group appears to occupy the equatorial posi-
tion. When the acyl chains are longer or contain aromatic substit-
uents, they can affect the gelation properties by hydrophobic
2. Results and discussion
To understand the structure and gelation property correlations,
especially the tolerance of acyl chain substituents of these simple
sugar derivatives (1–3), we synthesized a series of ester analogs
by a one-pot reaction using conditions similar to those reported
before.46 The structures of these compounds are shown in Figure
1. To determine the role of the terminal acetylene group in the
self-assembly process, we synthesized several analogs with similar
chain lengths as those in the good gelators 1–3. These include com-
pounds 5a–8c with chloro-substituents, terminal alkenyl, satu-
rated hydrocarbon, and branched alkyl chains. Compounds 9 and
10 contain 8 and 10 carbon acyl chains, and compound 11 contains
polymerizable methacrylate group. Compounds 12–13 contain
aromatic substituents.
After obtaining purified compounds, their gelation properties in
several solvents (hexane, water, ethanol and 1:1 water–ethanol)
were tested. The results for various ester derivatives of 4 are shown
in Table 1. These are listed according to their derivatization pat-
terns on the sugar ring so that we can compare the influence of
the acyl chains.
Previously, we had found that compounds containing long
diacetylene chains and short mono acetylene chains exhibit good
gelation properties in organic solvents or water. Here, we found
that the straight-chain derivatives and compounds with double
bonds, branched alkyl group, and chloro substituents are generally
not gelators in the same solvents tested: hexane, water, and an
ethanol–water mixture. Among the diesters with aliphatic acyl
chains (5a–11a), except 6a, none showed gelation in any of the
four solvents. The saturated alkyl chains tend to pack in a tighter
order compared to the alkynyl chains, thus leading to precipitation
from solution. The alkyne group disrupts the packing order, there-
by hindering the precipitation. However, for the benzoate and
naphthoate derivatives, they were able to gelate in an 1:1 etha-
interaction and
pꢀp stacking. However, when they are short chain
derivatives, they are not able to form gels in aqueous solution.
For the 2-monoesters 5b–13b, and 3-monoesters 5c–12c, the
compounds with C@C bonds and aryl substituents showed promis-
ing gelation results. Compound 6b contains a terminal alkene group
and it also does not gelate hexane or ethanol. However, it can form
unstable gels in water. The terminal double bond is less structurally
rigid compared to a triple bond. This may have accounted for the ob-
served gelation differences. The 3-chloro-butanoate 5c was able to
form opaque gels in pure water. The 2-methacrylate 11b can gelate
in pure water at about 2 wt %, and the 3-ester 11c can form gels in an
ethanol–water mixtureat ꢁ1 wt%. Thisfollowsthesametrendas we
observed in the monoacetylene lipids that short acyl chains lead to
good gelators. For aryl derivatives, the mono benzoates 12b and
12c do not form gels in the solvents tested. However, the 2-naphtho-
ate monoester 13b can form gels in aqueous mixtures, perhaps due
to thefact that p–pstackingamongthenaphthoylgroups is themain
driving force for gelation. There may also be hydrogen bonding be-
tween the hydroxyl group of the solvents with the oxygen from com-
pound 13b. If the 3-naphthalene derivative 13c can be prepared, it is
expected to be able to gelate ethanol water as well. However, during
the esterification reaction, the reaction is quite regioselective favor-
ing the 2-position.
To understand the structural requirements of 2-monoesters as
hydrogelators, we obtained a single crystal X-ray structure of the
analogous sugar lipid, the 2-chloro-butanoate derivative 5b. The
crystal structure is shown in Figure 3. Hydrogen bonding between
the 3-hydroxyl group and the anomeric oxygen forms a one-
dimensional array (Fig. 3b). In organic solvents, hydrogen bonding
is important for gelation. In aqueous solutions, hydrogen bonding
becomes unimportant, the hydrophobic interaction is the driving
nol–water mixture at 5 and 7 mg/mL, respectively. Aromatic
p–p
stacking plays an important role here, and presumably, hydrogen
bonding between the diester and the solvent hydroxyl groups also
contributed to the gelation. These resemble the behavior of long
chain diacetylene-containing compounds, which were also able
O
Ph
RCOCl
O
O
O
O
Ph
O
O
O
O
Ph
Ph
DCM, pyridine
O
O
O
HO
O
R
a
HO
O
OH
RT ~20hrs
O
O
OH
O
O
OCH3
OCH3
OCH3
OCH3
O
O
R
R
R
4
c
b
5a-c
6a-c
Cl
8a-c
9a-c
11a-c
12a-c
13a-b
R =
7a-c
10a-c
Figure 1. Structures of the synthesized diesters (a) and monoesters (b, c) .

S. Cheuk et al. / Carbohydrate Research 344 (2009) 417–425
419
Table 1
Gelation results of diesters (a), mono esters (b), and mono esters (c), the numbers shown are positive gelation concentrations in mg/mLa
Compound
R=
Hexane
P
H2O
I
EtOH
S
EtOH/H2O (1:1)
P
5a
Cl
*
6a
P
P
S
S
S
S
P
I
I
I
I
I
I
I
S
P
S
S
S
S
S
G
P
P
P
I
10
7a
8a
9a
10a
11a
12a
P
G 5
G 7
13a
P
I
S
5b
P
P
*
S
S
S
S
S
S
S
S
S
S
Cl
6b
P
G
P
S
P
P
G
P
I
12
S
7b
G 15
S
8b
P
S
P
P
P
I
S
9b
P
10b
11b
12b
13b
P
*
20
S
P
G 10
5c
P
P
S
P
P
S
I
G 7
P
S
S
S
S
S
S
S
P
P
P
P
P
P
Cl
6c
7c
P
8c
P
9c
P
10c
11c
P
P
*
I
G
9
12c
P
P
P
a
G: stable gel, G*: unstable gel, I: insoluble, P: precipitate, S: soluble at 20 mg/mL.
force for gelation. The crystal structure can help us to understand
the gelation properties of the alkynyl esters. It is safe to estimate
that the terminal acetylene derivatives would also assemble in a
similar fashion and form one-dimensional hydrogen bonded ar-
rays, as in 5b as they are very similar in structure. However, the
packing of the alkynyl chains is not as ordered as in 5b, therefore
they do not crystallize or precipitate, and form gels instead.
Because a balance between hydrophilicity and hydrophobicity
is necessary for gelation, we compared the CLogP (partition coeffi-
cient in water and octanol) values of several compounds with the
same chain length; these are shown in Chart 1. This analysis shows
an interesting trend versus gelation properties in water. Com-
pounds 2b, 6b, and 11b are able to form gels in water, and their
CLogP values are below 1.2; here, 2b has the lowest CLogP and is

420
S. Cheuk et al. / Carbohydrate Research 344 (2009) 417–425
3. Conclusions
We have synthesized a series of acyl derivatives of a simple su-
O
O
gar headgroup and analyzed the influence of the acyl chains on the
gelation properties. For ester derivatives with similar chain length,
the acyl chains give the best gelation results when they contain a
terminal acetylene function. Halide and saturated alkyl chains do
not gelate in hexane, ethanol, or ethanol–water mixture; aryl and
alkenyl derivatives give favorable gelation results in aqueous solu-
tions. X-ray crystal structures of a diester and a monoester gave
some insight into how they assemble in solution phase. The trends
observed here for gelation properties can be used in the design of
other hydrogelators.
O
O
O
O
O
O
11a
Figure 2. X-ray crystal structure of compound 11a.
the most efficient hydrogelator among these three. The saturated
alkyl derivatives 8b and 7b have higher CLogP values (>1.5), and
they are not gelators in water. This trend indicates that, for similar
structures, when considering structural modifications on the alkyl
chains, the CLogP values can perhaps be used to help predict the
gelation possibility in water.
4. Experimental
4.1. General methods
4.1.1. Gelation testing
We also characterized the morphologies of the dried gels
formed by several compounds; some of these are shown in Figure
4. The morphology showed dependence on the structure of the
gelators. The methacrylate derivatives 11b and 11c generally
formed a long fibrous network type of structures as shown in Fig-
ures 4a–e; the fibers are narrow, long and curved slightly. The SEM
image of part of the tubular-shaped rod showed that it is formed
by a bundle of much smaller fibers (Fig. 4c). Compound 11c formed
similar morphologies (Figs. 4d–e), somewhat more uniform in
width than the other ester 11b. The di-naphthalene derivative
13a formed more rigid and larger tubular type of structures in
wider diameter and straight manner (Fig. 4f). The mono-naphtha-
lene derivative 13b formed a softer fibrous assembly, which has
smaller diameters and is somewhat softer and showed bending
when a few strands of fibrous cross path (Fig. 4g–i). This reflects
that in compound 13b, which has only one naphthalene group,
The compounds were tested in a 1 dram vial with a rubber-
lined screw cap from Kimble. Approximately 2–4 mg of each
purified product and solvent were added into the vial. A starting
concentration of ꢁ20 mg/mL was used. The mixture was heated
to dissolve the compound (to give a homogeneous solution) and
was sonicated, if necessary. The solution was allowed to cool for
15–20 min. Then the vial was inverted, if no liquid flowed and if
the gels stayed at the bottom end of the upside down vial, the
gel was said to be stable. If a stable gel formed, serial dilution
was performed to find the minimum gelation concentration (MGC).
4.1.2. Optical microscopy
A small amount of the gel was placed on a clean glass slide and
was air-dried overnight. The xerogels were observed with an
Olympus BX60M optical microscope using a DSP Color Hi-Res
EXvision camera and an Olympus U-TV1X lens. The program used
to acquire and store the photos was Corel Photo-Paint 7.
the
pꢀp stacking interaction is not as strong as in 13a, therefore
it forms a less rigid tubular network in aqueous solution.
Hydrogen bond
acceptor
O
O
O
O
H
O
O
OMe
O
O
O
O
O
O
O
H
HO
O
OMe
O
O
O
O
Cl
O
OMe
O
O
H
O
O
Hydrogen bond
OMe
O
O
O
Cl
donor
HO
O
OMe
O
Cl
Cl
(a)
Cl
(b)
Figure 3. X-ray crystal structure of 4-chlorobutanoate monoester 5b. The monoester derivative (a) contains a hydrogen bond acceptor and donor, which enables them to
form one-dimensional bonding networks (b).
O
O
Ph
Ph
O
O
Ph
Ph
O
O
O
O
O
O
O
Ph
OCH3
O
O
O
HO
HO
HO
HO
O
O
O
HO
O
O
OCH3
O
O
OCH3
OCH3
O
O
O
OCH3
O
8b
CLogP = 1.5536
11b
CLogP = 0.732751
7b
CLogP = 1.6836
2b
CLogP = 0.6756
6b
CLogP = 1.1996
Chart 1. The CLogP values of several monoesters with similar chain length.

S. Cheuk et al. / Carbohydrate Research 344 (2009) 417–425
421
Figure 4. Optical micrographs (a, b, d–i) and scanning electron micrograph (c) of dried gels formed by compounds 11b, 11c, 13a, 13b. (a–c) Gels by 11b in water, 20 mg/mL,
(d, e) gels by 11c from EtOH–H2O, 1:1 at 9 mg/mL; (f) gels by 13a from EtOH–H2O, 1:1 at 7 mg/mL; (g–i) gels formed by 13b in EtOH–H2O, 1:1 at 10 mg/mL.
4.1.3. Scanning electron microscopy
Samples were prepared by drying the gel (20–30 lL) on an alu-
minum pellet in a desiccator under reduced pressure for several
acetone (19–9:1). The products are generally eluted in the order
of diester, 2-monoester, and 3-monoester. The characterization
data for the compounds synthesized are listed below.
days. A thin layer of platinum was deposited onto the pellet by a
Denton Vacuum (model Desk II) at
a
reduced pressure of
4.2.2. Methyl 4,6-O-benzylidene-2,3-di-O-(40-chlorobutanoyl)–
ꢁ30 mtorr and a current of 45 mA for 60 s. The sample was ana-
lyzed using a JEOL JSM 5410 scanning microscope with an EDAX
Detecting Unit PV9757/05.
a
-
D
-glucopyranoside (5a)
Compound 5a was isolated in 16% yield as a colorless oil. 1H
NMR (400 MHz, CDCl3) d 7.41–7.46 (m, 2H), 7.32–7.37 (m, 3H),
5.61 (t, 1H, J = 9.9 Hz), 5.51 (s, 1H), 4.96 (d, 1H, J = 3.7 Hz), 4.92
(dd, 1H, J = 3.7, 9.9 Hz), 4.31 (dd, 1H, J = 4.8, 10.3 Hz), 3.93 (dddꢁdt,
1H, J = 4.8, 9.5, 10.3 Hz), 3.78 (t, 1H, J = 10.3 Hz), 3.66 (ddꢁt, 1H,
J = 9.5, 9.9 Hz), 3.59 (t, 2H, J = 6.4 Hz), 3.53 (t, 2H, J = 6.4 Hz), 3.42
(s, 3H), 2.44–2.60 (m, 4H), 2.00–2.14 (m, 4H); 13C NMR
(100 MHz, CDCl3) d 171.9, 171.4, 136.7, 128.9, 128.0, 125.9,
101.3, 97.3, 78.9, 71.4, 68.8, 68.5, 62.1, 55.2, 43.7, 43.6, 30.8,
30.7, 27.2, 27.1. HRMS calcd for C22H29O8Cl2 [M+H]+ 491.1239,
found 491.1243.
4.2. Synthesis of compounds 5–13a–c
4.2.1. General procedure
Compound 4 (1–4 mmol) and 3–4 equiv of anhydrous pyridine,
and anhydrous dichloromethane (DCM, 5–10 mL) were mixed in a
round-bottom flask. The flask was protected with a calcium chlo-
ride drying tube and was cooled to 0–5 °C in an ice bath. The acid
chloride (1.3 equiv) was added to the reaction mixture. If the acid
chloride was not commercially available, it was prepared by treat-
ing the corresponding carboxylic acid with oxalyl chloride. The
temperature was warmed to room temperature and stirred for
20 h. The reactions were quenched by dilution with ꢁ10 mL of
DCM, and then washed with water (2 ꢂ 5 mL) and 5% cold NaHCO3
solution. The combined aqueous phase was extracted with 2 mL of
DCM, and the combined organic phase was dried over anhydrous
Na2SO4. The crude reaction mixtures were purified by flash chro-
matography on silica gel using various gradients of hexanes and
4.2.3. Methyl 4,6-O-benzylidene-2-O-(40-chlorobutanoyl)–
a-D-
glucopyranoside (5b)
Compound 5b was isolated as off-white crystals in 62% yield.
Mp 75.2–76.1 °C. 1H NMR (400 MHz, CDCl3) d 7.46–7.51 (m, 2H),
7.34–7.40 (m, 3H), 5.52 (s, 1H), 4.93 (d, 1 H, J = 3.9 Hz), 4.80 (dd,
1H, J = 3.9, 9.8 Hz), 4.28 (dd, 1H, J = 3.9, 9.8 Hz), 4.13 (t, 1H,
J = 9.8 Hz), 3.82 (dt, 1H, J = 4.9, 9.8 Hz), 3.73 (ddꢁt, 1H, J = 9.8,
10.7 Hz), 3.59 (t, 2H, J = 6.4 Hz), 3.51 (t, 1H, J = 9.8 Hz), 3.38 (s,

422
S. Cheuk et al. / Carbohydrate Research 344 (2009) 417–425
3H), 2.86 (br s, 1H), 2.58 (t, 2H, J = 7.3 Hz), 2.09 (p, 2H, J = 6.8 Hz);
13C NMR (100 MHz, CDCl3) d 172.3, 136.8, 129.2, 128.2, 126.2,
101.8, 97.3, 81.2, 73.4, 68.7, 68.4, 61.9, 55.3, 43.8, 31.0, 27.4. HRMS
calcd for C18H24O7Cl [M+H]+ 387.1211, found 387.1205.
33.8, 27.1, 26.9, 22.1, 22.0, 13.6. HRMS calcd for C24H35O8 [M+H]+
451.2332, found 451.2327.
4.2.9. Methyl 4,6-O-benzylidene-2-O-pentanoyl–a-D-
glucopyranoside (7b)
4.2.4. Methyl 4,6-O-benzylidene-3-O-(40-chlorobutanoyl)–
a
-D
-
Compound 7b was isolated as white crystals in a 44% yield. Mp
124.3–125.2 °C. 1H NMR (300 MHz, CDCl3) d 7.45–7.53 (m, 2H)
7.33–7.42 (m, 3H), 5.54 (s, 1H), 4.95 (d, 1H, J = 3.6 Hz), 4.79 (dd,
1H, J = 3.6, 9.6 Hz), 4.29 (dd, 1H, J = 3.9 Hz, 9.8), 4.16 (t, 1H,
J = 9.6 Hz), 3.84 (m, 1H), 3.75 (ddꢁt, 1H, J = 10.1Hz), 3.54 (ddꢁt,
1H, J = 9.2 Hz), 3.39 (s, 3H), 2.56 (br s, 1H), 2.41 (t, 2H, J = 7.5 Hz),
1.64 (p, 2H, J = 7.4 Hz), 1.36 (h, 2H, J = 7.4 Hz), 0.92 (t, 3H,
J = 7.3 Hz); 13C NMR (62.5 MHz, CDCl3) d 173.5, 136.9, 129.2,
128.3, 126.2, 101.9, 97.5, 81.3, 73.3, 68.8, 68.6, 61.9, 55.3, 33.8,
26.9, 22.0, 13.6. HRMS calcd for C19H27O7 [M+H]+ 367.1757, found
367.1752.
glucopyranoside (5c)
Compound 5c was isolated as off-white crystals in 10% yield.
Mp 154.4–155.1 °C. 1H NMR (400 MHz, CDCl3) d 7.41–7.46 (m,
2H), 7.33–7.38 (m, 3H), 5.50 (s, 1H), 5.34 (t, 1H, J = 9.9 Hz), 4.81
(d, 1H, J = 3.7 Hz), 4.31 (dd, 1H, J = 4.8, 10.3 Hz), 3.87 (dt, 1H,
J = 4.8, 9.9 Hz), 3.75 (t, 1H, J = 10.3 Hz), 3.70–3.63 (m, 1H), 3.59 (t,
1H, J = 9.5 Hz), 3.55 (t, 2H, J = 6.4 Hz), 3.47 (s, 3H), 2.57 (t, 2H,
J = 7.1 Hz), 2.20 (d, 1H, J = 11.7 Hz), 2.10 (p, 2H, J = 6.6 Hz); 13C
NMR (100 MHz, CDCl3) d 172.7, 136.9, 129.1, 128.2, 126.1, 101.5,
100.1, 78.6, 72.4, 71.7, 68.9, 62.7, 55.6, 43.8, 31.4, 27.8. HRMS calcd
for C18H24O7Cl [M+H]+ 387.1213, found 387.1211.
4.2.10. Methyl 4,6-O-benzylidene-3-O-pentanoyl–a-D-
glucopyranoside (7c)
4.2.5. Methyl 4,6-O-benzylidene-2,3-di-O-(40-pentenoyl)–
a
-D
-
glucopyranoside (6a)
Compound 7c was isolated as white needles in 11% yield. Mp
178.1–178.7 °C. 1H NMR (250 MHz, CDCl3) d 7.39–7.47 (m, 2H),
7.30–7.38 (m, 3H), 5.49 (s, 1H), 5.33 (t, 1H J = 9.6 Hz,), 4.80 (d,
1H, J = 4.1 Hz), 4.30 (dd, 1H, J = 4.6, 10.1 Hz), 3.86 (m, 1H), 3.75
(t, 1H, J = 10.1 Hz), 3.66 (m, 1H), 3.59 (ddꢁt, 1H, J = 9.1, 9.6 Hz),
3.47 (s, 3H), 2.37 (t, 2H, J = 7.6 Hz), 2.26 (br s, 1H), 1.61 (p, 2H,
J = 7.6 Hz), 1.31 (h, 2H, J = 7.8 Hz), 0.85 (t, 3H, J = 7.3 Hz); 13C
NMR (62.5 MHz, CDCl3) d 174.0, 137.0, 129.0, 128.2, 126.1, 101.4,
100.1, 78.7, 72.0, 71.8, 68.9, 62.7, 55.6, 34.1, 27.1, 22.0, 13.6. HRMS
calcd for C19H27O7 [M+H]+ 367.1757, found 367.1746.
The diester 6a was obtained as a clear oil in 50% yield. 1H NMR,
(250 MHz, CDCl3) d 7.41–7.51 (m, 2H), 7.30–7.40 (m, 3H), 5.79 (m,
2H), 5.64 (t, 1H, J = 9.6 Hz), 5.51 (s, 1H), 5.02–5.12 (m, 2H), 4.87–
5.01 (m, 4H), 4.31 (dd, 1H, J = 4.7, 10.1 Hz), 3.94 (dt, 1H, J = 4.7,
9.9 Hz), 3.77 (t, 1H, J = 10.1 Hz), 3.66 (t, 1H, J = 9.6 Hz), 3.40 (s,
3H), 2.26–2.51 (m, 8H); 13C NMR (62.5 MHz, CDCl3) d 172.2,
171.5, 136.8, 136.2, 136.1, 128.9, 128.0, 126.0, 115.5, 115.4,
101.4, 97.5, 79.1, 71.4, 68.7, 62.2, 55.2, 33.3, 33.1, 28.6, 28.5. HRMS
calcd for C24H31O8 [M+H]+ 447.2019, found 447.1976.
4.2.6. Methyl 4,6-O-benzylidene-2-O-(40-pentenoyl)–
a
-D
-
4.2.11. Methyl 4,6-O-benzylidene-2,3-di-O-(30-methyl-
glucopyranoside (6b)
butanoyl)–a-D-glucopyranoside (8a)
The ester 6b53 was isolated as viscous oil in a yield of 35%. 1H
NMR (250 MHz, CDCl3) d 7.45–7.55 (m, 2H), 7.33–7.43 (m, 3H),
5.85 (m, 1H), 5.55 (s, 1H), 5.98–5.14 (m, 2H), 4.94 (d, 1H,
J = 3.9 Hz), 4.80 (dd, 1H, J = 3.9, 9.6 Hz), 4.30 (m, 1H), 4.18 (ddꢁt,
1H, J = 9.6 Hz), 3.85 (m, 1H), 3.76 (ddꢁt, 1H, J = 9.1, 10.1 Hz), 3.56
(t, 1H, J = 9.1 Hz), 3.39 (s, 3H), 2.46–2.58 (m, 2H), 2.34–2.46 (m,
2H); 13C NMR (62.5 MHz, CDCl3) d 172.7, 137.0, 136.5, 129.3,
128.3, 126.3, 115.6, 102.0, 97.6, 81.3, 73.6, 68.8, 68.6, 62.0, 55.4,
33.3, 28.8. HRMS calcd for C19H24O7Na [M+Na]+ 387.1420, found
387.1407.
Diester 8a was isolated as a clear oil in 3% yield. 1H NMR (CDCl3,
400 MHz) d 7.40–7.46 (m, 2H), 7.31–7.37 (m, 3H), 5.63 (t, 1H,
J = 9.9 Hz), 5.50 (s, 1H), 4.97 (d, 1H, J = 3.7 Hz), 4.89 (dd, 1H,
J = 3.7, 9.9 Hz), 4.31 (dd, 1H, J = 4.8, 10.3 Hz), 3.93 (dt, 1H, J = 4.8,
9.9 Hz), 3.77 (t, 1H, J = 10.3 Hz), 3.64 (t, 1H, J = 9.5 Hz), 3.39 (s,
3H), 2.14-2.25 (m, 4H), 2.00–2.14 (m, 2H), 0.94 (d, 6H, J = 6.6 Hz),
0.89 (d, 6H, J = 6.2 Hz); 13C NMR (CDCl3, 100 MHz) d 172.5, 171.7,
137.0, 128.9, 128.1, 126.0, 101.4, 97.6, 79.4, 71.4, 68.8, 68.3, 62.3,
55.3, 43.3, 43.1, 25.8, 25.7, 22.2. HRMS calcd for C24H35O8 [M+H]+
451.2332, found 451.2315.
4.2.7. Methyl 4,6-O-benzylidene-3-O-(40-pentenoyl)–
glucopyranoside (6c)
a
-D
-
4.2.12. Methyl 4,6-O-benzylidene-2-O-(30-methyl-butanoyl)–
-glucopyranoside (8b)
Compound 8b was isolated as a crystalline white solid in 41%
a-
D
The ester 6c was isolated as a white solid in a yield of 9%. Mp
152.0–154.3 °C. 1H NMR (250 MHz, CDCl3) d 7.40–7.47 (m, 2H),
7.31–7.38 (m, 3H), 5.80 (m, 1H), 5.49 (s, 1H), 5.34 (t, 1H,
J = 9.6 Hz), 5.02 (m, 1H), 4.91 (m, 1H), 4.81 (d, 1H, J = 4.1 Hz),
4.31 (dd, 1H, J = 4.1, 9.6 Hz), 3.87 (m, 1H), 3.76 (m, 1H), 3.68 (m,
1H), 3.58 (ddꢁt, 1H, J = 9.1, 9.6 Hz), 3.47 (s, 3H), 2.31–2.53 (m,
4H), 2.20 (d, 1H, J = 11.4 Hz); 13C NMR (62.5 MHz, CDCl3) d 173.0,
136.9, 136.4, 128.9, 128.1, 126.1, 115.4, 101.4, 100.1, 78.6, 72.1,
71.7, 68.8, 62.7, 55.5, 33.5, 28.8. HRMS calcd for C19H25O7 [M+H]+
365.1600, found 365.1593.
yield. Mp 113.1–113.8 °C. 1H NMR (CDCl3, 400 MHz) d 7.45–7.52
(m, 2H), 7.32–7.40 (m, 3H), 5.52 (s, 1H), 4.94 (d, 1H, J = 3.7 Hz),
4.78 (dd, 1H, J = 3.7, 9.5 Hz), 4.27 (dd, 1H, J = 4.4, 9.9 Hz), 4.14 (t,
1H, J = 9.5 Hz), 3.82 (m, 1H), 3.73 (t, 1H, J = 10.3 Hz), 3.52 (ddꢁt,
1H, J = 9.2, 9.5 Hz), 3.37 (s, 3H), 2.92 (br s, 1H), 2.28 (d, 2H,
J = 7.0 Hz), 2.13 (m, 1H), 0.98 (d, 6H, J = 6.6 Hz); 13C NMR (CDCl3,
100 MHz) d 172.7, 136.9, 129.2, 128.2, 126.2, 101.8, 97.5, 81.3,
73.2, 68.7, 68.4, 61.9, 55.2, 43.1, 25.7, 22.1. HRMS calcd for
C19H27O7 [M+H]+ 367.1757, found 367.1742.
4.2.8. Methyl 4,6-O-benzylidene-2,3-di-O-pentanoyl–
glucopyranoside (7a)
a
-
D
-
4.2.13. Methyl 4,6-O-benzylidene-3-O-(30-methyl-butanoyl)–
-glucopyranoside (8c)
Compound 8c was isolated as a white solid in 14% yield. Mp
a-
D
Compound 7a was isolated as an oil in 5% yield. 1H NMR
(250 MHz, CDCl3) d 7.39–7.47 (m, 2H) 7.30–7.37 (m, 3H), 5.61 (t,
1H, J = 9.6 Hz), 5.50 (s, 1H), 4.86–4.96 (m, 2H), 4.30 (dd, 1H,
J = 4.7, 9.9 Hz), 3.93 (dt, 1H, J = 4.7, 9.6 Hz), 3.77 (ddꢁt, 1H,
J = 10.3 Hz), 3.64 (t, 1H, J = 9.6 Hz), 3.40 (s, 3H), 2.31 (m, 4H),
1.58 (m, 4H), 1.31 (m, 4H), 0.91 (t, 3H, J = 7.3 Hz), 0.83 (t, 3H,
J = 7.3 Hz); 13C NMR (62.5 MHz, CDCl3) d 173.2, 172.5, 136.9,
129.0, 128.1, 126.1, 101.5, 97.7, 79.3, 71.4, 68.8, 68.5, 62.3, 55.4,
161.7–162.8 °C. 1H NMR (CDCl3, 400 MHz) d 7.38–7.46 (m, 2H),
7.30–7.36 (m, 3H), 5.48 (s, 1H), 5.32 (t, 1H, J = 9.5 Hz), 4.79 (d,
1H, J = 3.7 Hz), 4.29 (dd, 1H, J = 4.8, 9.9 Hz), 3.85 (m, 1H, J = 4.8,
9.9 Hz), 3.74 (t, 1H, J = 10.3 Hz), 3.64 (m, 1H, J = 3.7, 9.5 Hz), 3.57
(t, 1H, J = 9.5 Hz), 3.45 (s, 3H), 2.23 (d, 2H, J = 7.0 Hz), 2.08 (m,
1H), 0.91 (d, 6H, J = 6.6 Hz); 13C NMR (CDCl3, 100 MHz) d 173.3,
136.9, 129.0, 128.1, 126.0, 101.4, 100.2, 78.7, 71.9, 71.6, 68.9,

S. Cheuk et al. / Carbohydrate Research 344 (2009) 417–425
423
62.6, 55.6, 43.5, 25.9, 22.2. HRMS calcd for C19H26O7Na [M+Na]+
389.1576, found 389.1570.
3.53 (t, 1H, J = 9.5 Hz), 3.37 (s, 3H), 2.39 (t, 2H, J = 7.5 Hz), 1.62
(m, 2H), 1.19–1.36 (m, 12H), 0.88 (t, 3H, J = 6.8 Hz); 13C NMR
(100 MHz, CDCl3) d 173.5, 136.9, 129.2, 128.2, 126.2, 101.8, 97.5,
81.2, 73.3, 68.7, 68.5, 61.9, 55.3, 34.0, 31.8, 29.3, 29.2, 28.9, 24.8,
22.6, 14.0. HRMS calcd for C24H37O7 [M+H]+ 437.2539, found
437.2530.
4.2.14. Methyl 4,6-O-benzylidene-2,3-di-O-octanoyl–a-D-
glucopyranoside (9a)
Compound 9a was isolated as a white powder in 35% yield. Mp
46.9–48.7 °C. 1H NMR (400 MHz, CDCl3) d 7.40–7.46 (m, 2H), 7.30–
7.36 (m, 3H), 5.61 (t, 1H, J = 9.8 Hz), 5.50 (s, 1H), 4.94 (d, 1H,
J = 2.9 Hz), 4.91 (dd, 1H, J = 4.8, 9.8 Hz), 4.30 (dd, 1H, J = 4.9 Hz,
10.7), 3.92 (dt, 1H, J = 4.8, 9.8 Hz), 3.76 (ddꢁt, 1H, J = 9.8,
10.7 Hz), 3.64 (t, 1H, J = 9.8 Hz), 3.39 (s, 3H), 2.30 (m, 4H), 1.59
(m, 4H), 1.10–1.36 (m, 16H), 0.84 (m, 6H); 13C NMR (100 MHz,
CDCl3) d 173.1, 172.4, 136.8, 128.9, 128.0, 126.0, 101.3, 97.6,
79.2, 71.3, 68.7, 68.5, 62.2, 55.2, 34.2, 34.0, 31.6, 31.5, 28.9, 28.8,
25.0, 24.8, 22.5, 13.9. HRMS calcd for C30H46O8Na [M+Na]+
557.3090, found 557.3066.
4.2.19. Methyl 4,6-O-benzylidene-2-O-decanoyl–a-D-
glucopyranoside (10c)
Compound 10c was isolated as a white powder in 11% yield. Mp
117.1–118.2 °C. 1H NMR (400 MHz, CDCl3) d 7.41–7.47 (m, 2H),
7.31–7.37 (m, 3H), 5.49 (s, 1H), 5.34 (t, 1H, J = 9.7 Hz), 4.80 (d,
1H, J = 3.7 Hz), 4.30 (dd, 1H, J = 4.8, 9.9 Hz), 3.86 (td, 1H, J = 4.7,
9.8 Hz), 3.74 (t, 1H, J = 10.3 Hz), 3.66 (dd, 1H, J = 3.7, 9.5 Hz), 3.58
(t, 1H, J = 9.5 Hz), 3.44 (s, 3H), 2.37 (t, 2H, J = 7.3 Hz), 1.62 (m,
2H), 1.12–1.39 (m, 12H), 0.87 (t, 3H, J = 7.0 Hz); 13C NMR
(100 MHz, CDCl3) d 173.8, 136.9, 128.9, 128.0, 126.0, 101.3,
100.0, 78.6, 71.9, 71.6, 68.8, 62.6, 55.4, 34.3, 31.7, 29.3, 29.2,
28.8, 25.0, 22.6, 14.0. HRMS calcd for C24H37O7 [M+H]+ 437.2539,
found 437.2527.
4.2.15. Methyl 4,6-O-benzylidene-2-O-octanoyl–a-D-
glucopyranoside (9b)
Compound 9b54 was isolated as white crystals in 50% yield. Mp
59.7–60.8 °C. 1H NMR (400 MHz, CDCl3) d 7.47–7.52 (m, 2H), 7.33–
7.40 (m, 3H), 5.51 (s, 1H), 4.94 (d, 1H, J = 3.9 Hz), 4.77 (dd, 1H,
J = 3.9, 9.8 Hz), 4.27 (dd, 1H, J = 4.9, 9.8 Hz), 4.13 (t, 1H,
J = 9.8 Hz), 3.81 (m, 1H), 3.72 (ddꢁt, 1H, J = 9.8, 10.7 Hz), 3.50
(ddꢁt, 1H, J = 8.8, 9.8 Hz), 3.36 (s, 3H), 2.94 (br s, 1H), 2.39 (t, 2H,
J = 7.3 Hz), 1.64 (m, 2H), 1.20–1.38 (m, 8H), 0.88 (t, 3H,
J = 6.8 Hz); 13C NMR (100 MHz, CDCl3) d 173.4, 136.9, 129.1,
128.1, 126.2, 101.8, 97.4, 81.2, 73.2, 68.7, 68.4, 61.9, 55.2, 33.9,
31.5, 28.8, 24.8, 22.4, 13.9. HRMS calcd for C22H33O7 [M+H]+
409.2226, found 409.2207.
4.2.20. Methyl 4,6-O-benzylidene-2,3-di-O-(20-methylacrolyl)–
a-
D-glucopyranoside (11a)
Methacrylic acid was used as the starting material, in 1.2 equiv
relative to compound 4. Compound 11a55 was isolated as needle-
like crystals in 2% yield. Mp 106.6–107.4 °C. 1H NMR (400 MHz,
CDCl3) d 7.41–7.47 (m, 2H), 7.31–7.37 (m, 3H), 6.14 (s, 1H), 6.04
(s, 1H), 5.75 (t, 1H, J = 9.8 Hz), 5.60 (s, 1H), 5.53 (s, 2H), 5.03 (d,
1H, J = 3.9 Hz), 4.97 (dd, 1H, J = 3.9, 9.8 Hz), 4.32 (dd, 1H, J = 4.9,
9.8 Hz), 3.97 (dt, 1H, J = 4.9, 9.8 Hz), 3.80 (ddꢁt, 1H, J = 9.8,
10.7 Hz), 3.75 (t, 1H, J = 9.8 Hz), 3.40 (s, 3H), 1.90 (br s, 6H); 13C
NMR (100 MHz, CDCl3) d 166.8, 166.1, 136.8, 135.7, 135.1, 128.9,
128.0, 127.1, 126.0, 125.7, 101.4, 97.6, 79.1, 72.1, 69.1, 68.7, 62.3,
55.2, 18.2, 18.0. HRMS calcd for C22H27O8 [M+H]+ 419.1706, found
419.1702.
4.2.16. Methyl 4,6-O-benzylidene-3-O-octanoyl–a-D-
glucopyranoside (9c)
Compound 9c was isolated as a white powder in 15% yield. Mp
117.1–118.2 °C. 1H NMR (400 MHz, CDCl3) d 7.40–7.47 (m, 2H),
7.32–7.38 (m, 3H), 5.49 (s, 1H), 5.34 (t, 1H, J = 9.8 Hz), 4.80 (d,
1H, J = 3.9 Hz), 4.30 (dd, 1H, J = 4.9, 9.8 Hz), 3.87 (dd, 1H, J = 4.9,
9.8 Hz), 3.75 (ddꢁt, 1H, J = 9.8, 10.7 Hz), 3.66 (m, 1H), 3.58 (t, 1H,
J = 9.8 Hz), 3.47 (s, 3H), 2.37 (t, 2H, J = 7.3 Hz), 2.24 (d, 1H,
J = 11.7 Hz), 1.62 (m, 2H), 1.02–1.36 (m, 8H), 0.85 (t, 3H, J = 6.8);
13C NMR (100 MHz, CDCl3) d 173.9, 137.0, 129.0, 128.1, 126.1,
101.4, 100.1, 78.6, 72.0, 71.8, 68.9, 62.7, 55.5, 31.6, 28.9, 25.0,
22.5, 14.0. HRMS calcd for C22H33O7 [M+H]+ 409.2226, found
409.2209.
4.2.21. Methyl 4,6-O-benzylidene-2-O-(20-methylacrolyl)–
a-D-
glucopyranoside (11b)
Compound 11b55 was isolated as viscous oil in 67% yield. 1H
NMR (400 MHz, CDCl3) d 7.47–7.53 (m, 2H), 7.34–7.41 (m, 3H),
6.21 (s, 1H), 5.63 (s, 1H), 5.53 (s, 1H), 4.97 (d, 1H, J = 3.9 Hz), 4.82
(dd, 1H, J = 3.9, 9.8 Hz), 4.28 (dd, 1H, J = 4.9, 10.7 Hz), 4.20 (ddꢁt,
1H, J = 8.8, 9.8 Hz), 3.84 (dt, 1H, J = 4.9, 9.8 Hz), 3.74 (ddꢁt, 1H,
J = 9.8, 10.7 Hz), 3.53 (ddꢁt, 1H, J = 8.8, 9.8 Hz), 3.37 (s, 3H), 2.77
(br s, 1H), 1.97 (s, 3H); 13C NMR (100 MHz, CDCl3) d 166.9, 136.9,
135.5, 129.2, 128.2, 126.7, 126.2, 101.9, 97.5, 81.3, 73.8, 68.7,
68.5, 61.9, 55.3, 18.1. HRMS calcd for C18H23O7 [M+H]+ 351.1444,
found 351.1436.
4.2.17. Methyl 4,6-O-benzylidene-2,3-di-O-decanoyl–a-D-
glucopyranoside (10a)
Compound 10a was isolated as a white powder in 21% yield. Mp
46.9–48.7 °C. 1H NMR (400 MHz, CDCl3) d 7.40–7.45 (m, 2H), 7.30–
7.36 (m, 3H), 5.61 (t, 1H, J = 9.9 Hz), 5.49 (s, 1H), 4.94 (d, 1H,
J = 3.7 Hz), 4.91 (dd, 1H, J = 3.7 Hz, 9.9 Hz), 4.29 (dd, 1H, J = 4.8,
10.3 Hz), 3.92 (dt, 1H, J = 4.8, 9.9 Hz), 3.76 (t, 1H, J = 10.3 Hz),
3.64 (t, 1H, J = 9.5 Hz), 3.39 (s, 3H), 2.20–2.42 (m, 4H), 1.58 (m,
4H), 1.13–1.39 (m, 24H), 0.84–0.91 (m, 6H); 13C NMR (100 MHz,
CDCl3) d 173.1, 172.4, 136.8, 128.9, 128.0, 126.0, 101.4, 97.6,
79.2, 71.3, 68.7, 68.5, 62.2, 55.2, 34.2, 34.0, 31.8, 29.34, 29.28,
29.2 (br), 29.0, 28.9, 25.0, 24.8, 22.6, 14.0. HRMS calcd for
C34H55O8 [M+H]+ 591.3897, found 591.3878.
4.2.22. Methyl 4,6-O-benzylidene-3-O-(20-methylacrolyl)–
a-D-
glucopyranoside (11c)
Compound 11c55 was isolated as off-white crystals in 10% yield.
Mp 185.0–186.0 °C. 1H NMR (400 MHz, CDCl3) d 7.41–7.48 (m, 2H),
7.32–7.39 (m, 3H), 6.17 (s, 1H), 5.59 (s, 1H), 5.51 (s, 1H), 5.40 (t, 1H,
J = 9.8 Hz), 4.82 (d, 1H, J = 3.9 Hz), 4.32 (dd, 1H, J = 4.9, 10.7 Hz),
3.89 (m, 1H), 3.77 (ddꢁt, 1H, J = 9.8, 10.7 Hz), 3.72 (m, 1H), 3.66
(t, 1H, J = 9.8 Hz), 3.47 (s, 3H), 2.44 (d, 1H, J = 11.7 Hz), 1.96 (s,
3H); 13C NMR (100 MHz, CDCl3) d 167.4, 137.0, 135.9, 129.0,
128.1, 126.3, 126.1, 101.3, 100.1, 78.7, 72.6, 71.9, 68.8, 62.6, 55.5,
18.3. HRMS calcd for C18H23O7 [M+H]+ 351.1444, found 351.1451.
4.2.18. Methyl 4,6-O-benzylidene-2-O-decanoyl–a-D-
glucopyranoside (10b)
Compound 10b54 was isolated as a white powder in 59% yield.
Mp 59.7–60.8 °C. 1H NMR (400 MHz, CDCl3) d 7.46–7.52 (m, 2H),
7.33–7.39 (m, 3H), 5.50 (s, 1H), 4.94 (d, 1H, J = 3.7 Hz), 4.78 (dd,
1H, J = 3.7, 9.5 Hz), 4.28 (dd, 1H, J = 4.4, 9.9 Hz), 4.15 (t, 1H,
J = 9.5 Hz), 3.82 (dt, 1H, J = 4.4, 9.9 Hz), 3.73 (t, 1H, J = 10.3 Hz),
4.2.23. Methyl 4,6-O-benzylidene-2,3-di-O-benzoyl–a-D-
glucopyranoside (12a)
Compound 12a56,57 was isolated as a white solid in 6% yield. Mp
152.4–153.0 °C. 1H NMR (400 MHz, CDCl3) d 7.95–8.07 (m, 4H),
7.28–7.56 (m, 11H), 6.08 (t, 1H, J = 9.9 Hz), 5.58 (s, 1H), 5.27 (dd,

424
S. Cheuk et al. / Carbohydrate Research 344 (2009) 417–425
1H, J = 3.7, 9.9 Hz), 5.20 (d, 1H, J = 3.7 Hz), 4.39 (dd, 1H, J = 4.8,
10.3 Hz), 4.10 (dt, 1H, J = 4.8, 9.9 Hz), 3.92 (t, 1H, J = 9.5 Hz), 3.88
(t, 1H, J = 10.3 Hz), 3.44 (s, 3H); 13C NMR (100 MHz, CDCl3) d
166.0, 165.6, 136.8, 133.3, 133.0, 130.0, 129.7, 129.0, 128.4,
128.2, 128.1, 126.1, 101.6, 97.8, 79.3, 72.5, 69.5, 68.9, 62.5, 55.5.
Hopkinson and Jennifer Vu for their help in preparing some
intermediates.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.carres.2008.12.006.
4.2.24. Methyl 4,6-O-benzylidene-2-O-benzoyl–a-D-
glucopyranoside (12b)
Compound 12b58 was isolated as a crystalline solid in 42% yield.
Mp 170.3–170.9 °C. 1H NMR (400 MHz, CDCl3) d 8.08–8.12 (m, 2H),
7.56–7.61 (m, 1H), 7.50–7.54 (m, 2H), 7.43–7.48 (m, 2H), 7.37–7.41
(m, 3H), 5.57 (s, 1H), 5.08 (d, 1H, J = 3.7 Hz), 5.04 (dd, 1H, J = 3.7,
9.2 Hz), 4.36 (ddꢁt, 1H, J = 9.2, 9.5 Hz), 4.34 (d, 1H, J = 4.8,
10.3 Hz), 3.92 (dt, 1H, J = 4.8, 10.3 Hz), 3.80 (t, 1H, J = 10.3 Hz),
3.63 (ddꢁt, 1H, J = 9.2, 9.5 Hz), 3.40 (s, 3H), 2.74 (br s, 1H); 13C
NMR (100 MHz, CDCl3) d 166.2, 137.0, 133.3, 129.9, 129.4, 129.2,
128.4, 128.3, 126.3, 102.0, 97.8, 81.4, 74.0, 68.9, 68.8, 62.0, 55.5.
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4.2.25. Methyl 4,6-O-benzylidene-3-O-benzoyl–a-D-
glucopyranoside (12c)
Compound 12c56 was isolated as white needle-like crystals in
10% yield. Mp 216.6–217.0 °C. 1H NMR (400 MHz, CDCl3) d 8.08
(d, 2H, J = 7.7 Hz), 7.55 (t, 1H, J = 7.3 Hz), 7.39–7.46 (m, 4H),
7.28–7.34 (m, 3H), 5.60 (t, 1H, J = 9.5 Hz), 5.54 (s, 1H), 4.86 (d,
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4.2.26. Methyl 4,6-O-benzylidene-2,3-di-O-napthoyl–a-D-
glucopyranoside (13a)
Compound 13a was isolated as white crystalline solid in a 13%
yield. Mp 131.6–132.1 °C. 1H NMR (400 MHz, CDCl3) d 8.94 (d, 1H,
J = 8.8 Hz), 8.66 (d, 1H, J = 8.8 Hz), 8.32 (d, 1H, J = 7.8 Hz), 7.97–8.02
(m, 2H), 7.92 (d, 1H, J = 7.8 Hz), 7.85 (d, 1H, J = 7.8 Hz), 7.80 (d, 1H,
J = 8.8 Hz), 7.31–7.58 (m, 11H), 6.25 (t, 1H, J = 9.8 Hz), 5.64 (s, 1H),
5.45 (dd, 1H, J = 3.9, 9.8 Hz), 5.29 (d, 1H, J = 3.9 Hz), 4.43 (dd, 1H,
J = 4.9, 9.8 Hz), 4.17 (dt, 1H, J = 4.9, 9.8 Hz), 3.99 (ddꢁt, 1H,
J = 8.8, 9.8 Hz), 3.91 (t, 1H, J = 9.8, 10.7 Hz), 3.51 (s, 3H); 13C NMR
(100 MHz, CDCl3) d 166.7, 166.6, 136.9, 134.1, 133.7, 133.5,
132.9, 131.3, 130.9, 129.2, 129.0, 128.5, 128.3, 128.2, 127.9,
127.5, 127.4, 126.1, 125.5, 125.3, 124.6, 124.4, 101.5, 98.0, 79.5,
72.2, 69.6, 68.9, 62.6, 55.5. HRMS calcd for C36H31O8 [M+H]+
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4.2.27. Methyl 4,6-O-benzylidene-2-O-napthoyl–a-D-
glucopyranoside (13b)
Compound 13b was isolated as white crystals in 83% yield. Mp
174.6–175.0 °C. 1H NMR (400 MHz, CDCl3) d 8.92 (d, 1H, J = 8.8 Hz),
8.27 (d, 1H, J = 7.8 Hz), 8.04 (d, 1H, J = 7.8 Hz), 7.89 (d, 1H,
J = 8.8 Hz), 7.63 (m, 1H), 7.48–7.58 (m, 4H), 7.35–7.43 (m, 3H),
5.59 (s, 1H), 5.21 (d, 1H, J = 3.9 Hz), 5.14 (dd, 1H, J = 3.9, 9.8 Hz),
4.39 (ddꢁt, 1H, J = 8.8, 9.8 Hz), 4.35 (dd, 1H, J = 4.9, 9.8 Hz), 3.95
(dt, 1H, J = 3.9, 9.8 Hz), 3.82 (ddꢁt, 1H, J = 9.8, 10.7 Hz), 3.67 (ddꢁt,
1H, J = 8.8, 9.8 Hz), 3.45 (s, 3H), 2.63 (br s, 1H); 13C NMR (100 MHz,
CDCl3) d 167.2, 136.9, 133.8, 131.3, 130.8, 129.3, 128.5, 128.4,
127.9, 126.5, 126.3, 125.7, 124.5, 102.0, 97.7, 81.4, 74.2, 68.9,
68.8, 62.0, 55.5. HRMS calcd for C25H25O7 [M+H]+ 437.1600, found
437.1589.
Acknowledgments
We are grateful for financial support from NSF, CHE518283. The
project was also supported in part by Louisiana Board of Regents
Graduate Fellowship to Sherwin Cheuk. We also thank Branden

S. Cheuk et al. / Carbohydrate Research 344 (2009) 417–425
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