Expeditious preparation of triazole-linked glycolipids via microwave accelerated click chemistry and their electrochemical and biological assessments

Article abstract of DOI:10.1016/j.tet.2010.10.033

A series of triazole-linked ester-type glycolipids were efficiently prepared via a two-step sequence involving microwave accelerated 'click' chemistry and debenzylation. All carbon chain length varied O-alkynyl fatty esters used to couple with 1-azido-tet

Full text of DOI:10.1016/j.tet.2010.10.033

Tetrahedron 66 (2010) 9974e9980
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Expeditious preparation of triazole-linked glycolipids via microwave accelerated
click chemistry and their electrochemical and biological assessments
,
d
,
a
b,
Shao-Xing Song a, Hai-Lin Zhang a, Chol-Guk Kim a, Li Sheng b, Xiao-Peng He c , Yi-Tao Long , Jia Li
,
*
*
,
Guo-Rong Chen a
*
a Key Laboratory for Advanced Materials and Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology,
Shanghai 200237, PR China
b National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, PR China
c Department of Pharmaceutical Engineering, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, PR China
d PPSM, ENS Cachan, CNRS, 61 av. President Wilson, F-94230 Cachan, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 July 2010
Received in revised form 27 September 2010
Accepted 15 October 2010
Available online 18 November 2010
A series of triazole-linked ester-type glycolipids were efficiently prepared via a two-step sequence in-
volving microwave accelerated ‘click’ chemistry and debenzylation. All carbon chain length varied
O-alkynyl fatty esters used to couple with 1-azido-tetra-O-benzyl-b-D-glucoside showed excellent tol-
erance to the microwave-assisted 1,3-dipolar cycloaddition (click reaction), forming the unique cyclo-
adducts in almost quantitative yields of 92.9e99.0% within a quarter. The desired glycolipids were then
readily afforded via the successive hydrogenolysis promoted by PdCl2/H2. Their adsorption competence
on gold electrode were evaluated through EIS (electrochemical impedance spectroscopy) measurement
and the resulting structureeactivity relationship (SAR) was discussed. In addition, the cytotoxicity of this
triazolyl glycolipid class on HeLa (cervix cancer) cell line was identified by MTT assay.
Ó 2010 Elsevier Ltd. All rights reserved.
Keywords:
Glycolipid derivatives
Microwave-assisted click chemistry
EIS measurement
Gold surface adsorption
Cytotoxicity
1. Introduction
The incorporation of ‘click’ chemistry9 with microwave irradi-
ation that may tremendously enhance the reaction rate10 has re-
Glycolipids represent a class of crucial glycoconjugate structure in
which the naturally occurring carbohydrates and lipids are co-
valently coupled. They constitute animal or plant membranes and
are of considerable biological and physiochemical interest.1 The
cently become a laboratorial preference toward the construction of
combinatorial compound libraries.11b A plethora of investigations
were reported on the click chemistry-based carbohydrate re-
search11 fulfilled under either conventional or microwave-assisted
conditions.12 However, research on the preparation of synthetic
triazolyl glycolipid derivatives as well as their potential func-
tions6,13 was still in its infancy. Loganathan and co-workers first
described a general method for the synthesis of ether-type glyco-
lipid derivatives via 1,3-dipolar cycloaddition.13a A very recent re-
port by Krausz and co-workers also revealed the interesting
physiochemical property of several fatty acid-contained triazolyl
glycolipids.13b Enlightened by such innovative and promising work,
we envisioned to synthesize a series of ester-type glycolipid de-
rivatives via click chemistry while their newly explored functions
were also reported.
identification of a-GalCer (a-galactosyl ceramide) as CD1d (an au-
toimmunity-related protein) binding ligands well exemplified the
qualification of natural glycolipids as cell surface associated anti-
gens.2 In addition, some glycolipid derivatives have also been de-
veloped as ion-pairing agents for oral drug delivery,3 cell adhesion
mediators4 as well as potential anticancer agents toward the in-
hibition of cell proliferation5e7 due to their lipophilic feature. Besides
their compelling biological versatility, the amphiphilic glycolipids
have simultaneously proven practical as non-ionic surfactants that
are environmentally friendly due to the low toxic and highly bio-
compatible nature of carbohydrates.8 Consequently, the efficient
preparation of such multifunctional glycoconjugate series is of great
interest.
Notably, former relevant studies were mainly devoted to the
change of the hydrophilic carbohydrate moieties toward the di-
versification of glycolipid derivatives synthesized, whereas only
a limited scope of hydrophobic lipid chain was employed. As shown
in Scheme 1, we particularly emphasized in this study the impact of
length variation of lipid chain toward the reaction tolerance as well
* Corresponding authors. Tel.: þ86 021 64253016; fax: þ86 021 64252758;
e-mail addresses: 020060205@ecust.edu.cn (X.-P. He), jli@mail.shcnc.ac.cn (J. Li),
mrs_guorongchen@ecust.edu.cn (G.-R. Chen).
0040-4020/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.10.033

S.-X. Song et al. / Tetrahedron 66 (2010) 9974e9980
9975
as related functions of the formed glycolipids. Nine fatty acids (with
carbon numbers of 5, 7, 9, 12, 13, 14, 15, 16, and 18, respectively)
were utilized as starting materials to prepare various lipid alkynes
and CuSO4$5H2O (0.2 equiv). The mixture was then transferred to
the microwave oven (YL8023B1, Yalian Company) at 55 ꢀC for
a ramp time of 2 min and hold time of 12 min with vigorous stir-
ring. TLC monitoring (by spraying with 6 N H2SO4 and charring at
300 ꢀC) indicated that all starting materials had been fully con-
verted in this 14-min pattern to the unique crude products, which
were successively purified by extraction and column chromatog-
raphy. To our surprise, all carbon chain length varied O-alkynyl fatty
esters have proven tolerable toward the microwave-assisted click
reaction, affording the desired products 11e19 in excellent yields of
92.9e99.0% (Table 1).
for achieving the click reaction with the 1-azido-tetra-O-benzyl-
b-
D-glucosyl donor (1, Scheme 1). Microwave irradiation was
introduced into this key step for evaluating whether the corre-
sponding reactivity would be enhanced. Parallel click reactions
were also conducted under conventional condition (stirring at rt)
and the comparable results were discussed.
Table 1
Click products (11e19) and debenzylated glycolipids (20e28) yielded via Scheme 1
Compd
Yield (%)a
Yield (%)b
Compd
Yield (%)
11
12
13
14
15
16
17
18
19
92.9
97.7
99.0
96.6
96.5
98.3
96.1
96.6
98.3
97.1
94.7
93.5
98.8
96.9
96.7
95.7
94.5
95.2
20
21
22
23
24
25
26
27
28
90.5
92.5
83.7
66.1
84.4
72.3
90.6
75.1
85.5
a
This is fulfilled under microwave irradiation within 14 min.
This is fulfilled by stirring under rt within 6 h.
b
Next, for validating the predominance of the microwave-assis-
ted click chemistry, we performed the same reaction under con-
ventional condition. Such result was listed in Table 1. Clearly, all
click reactions stirring at room temperature was much more slug-
gish, which required approximately 6 h (consecutive monitoring by
TLC every 30 min for the first 1 h and every 1 h for the rest 5 h) for
complete conversion. In addition, compared with the microwave-
assisted reactions, excessive catalyst loading (VcNa from 0.4 equiv
to 6 equiv, CuSO4$5H2O from 0.2 equiv to 3 equiv) was required
toward those accomplished conventionally within such timeframe
for retaining the final yields (93.5e98.8%). The experimental out-
come above described has thus demonstrated the introduction of
microwave irradiation into the present case desirable for tremen-
dously accelerating the reaction rate and enhancing the reactivity.
This may alternatively represent a facile methodology toward the
expeditious preparation of the triazolyl glycolipid series.
Scheme 1. Synthetic route of triazole-linked glycolipids, reagents and conditions: (a)
VcNa (0.4 equiv)/CuSO4$5H2O (0.2 equiv) under Mw. or VcNa (6 equiv)/CuSO4$5H2O
(3 equiv) at rt in CH2Cl2/H2O; (b) PdCl2/H2 in MeOH.
Furthermore, two brand new functions of this specific triazolyl
glycolipid class were disclosed by our further analysis via electro-
chemistry and MTT assay. First, it is well documented that triazole
derivatives could form protecting film on metal surface for corro-
sion inhibition.14 We have thus performed EIS measurement on
gold electrode coated by the triazolyl glycolipids for the modeling
study of their initial adsorption competence. The resulting SAR in
an interesting carbon chain length-dependent manner was se-
quentially elucidated. Next, the cytotoxicity of this triazolyl glyco-
lipid class on HeLa (cervix cancer) cell line was identified by MTT
assay.
Eventually, the afforded click products (11e19) were debenzy-
lated with careful manipulation (see experimental Section 4.2.)
under a PdCl2/H2 promoted16b system (Scheme 1), which gave the
desired alcohols (20e28) in moderate-to-good yields of 66.1e92.5%
(Table 1).
2.2. Electrochemical measurement
2. Result and discussion
2.1. Synthesis
Numerous lipid chain-containing organic compounds were
identified as corrosion inhibitors, which may economically and
practically reduce corrosive attack on metals.17,18 However, most of
the currently reported inhibitors suffer from their environmentally
toxic nature and are thereby limited for further industrialization.19
Glycolipids represent a class of highly biocompatible substances
with extremely low toxicity and fast biodegradation. They were
proposed as green surfactants5 and the physiochemical property of
several triazole-linked glycolipids was revealed recently.13b In ad-
dition, triazole derivatives have also been evaluated as potent an-
ticorrosion agents due to their N-heterocyclic nature.14 Prompted
by such compelling evidence, we tended to investigate the ad-
sorption competence of our triazolyl glycolipids on metals. EIS
measurement on gold electrode was employed as the preliminary
analysis model involving various chain length varied samples
(20e28).
As shown in Scheme 1, the known azido glucoside 115 was
employed as the glycodonor for coupling with various terminal O-
alkynes. Commercially available valeric, heptylic, pelargonic, lauric,
tridecanoic, myristic, pentadecanoic, palmitic and stearic acids
have been previously converted to the corresponding O-alkynyl
fatty esters (2e10) in the presence of 1.5 equiv K2CO3 and 1.5 equiv
propargyl bromide in dry DMF.16a
With azide and alkyne materials ready, the Cu(I)-catalyzed 1,3-
dipolar cycloaddition (click reaction) via microwave irradiation was
then attempted. Initially, the azido glucoside (1) and different O-
alkynes (2e10) were dissolved in CH2Cl2/H2O (1:1, v/v), followed by
the addition of catalytic amount of sodium ascorbate (0.4 equiv)

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S.-X. Song et al. / Tetrahedron 66 (2010) 9974e9980
Table 2
The surface coverage (
electrodes
q) and inhibition efficiency (P) of different films covered gold
Compd
Alkyl
Rct (k
U
cm2)
ΔRct (k
U
cm2)b
1ꢁqc
d
P (%)d
d
d
0.063a
0.260
0.587
0.885
2.066
2.675
2.260
1.657
1.112
0.769
d
d
20
21
22
23
24
25
26
27
28
C5
C7
C9
C12
C13
C14
C15
C16
C18
þ0.197
þ0.327
þ0.298
þ1.181
þ0.609
ꢁ0.415
ꢁ0.603
ꢁ0.545
ꢁ0.343
0.241
0.107
0.071
0.031
0.024
0.028
0.038
0.057
0.082
75.9
89.3
92.9
96.9
97.6
97.2
96.2
94.3
91.8
a
This is the Rct value without films (see Fig. S1).
This is the Rct difference between the present entry and the last entry.
This is calculated via formula (1).
b
c
d
This is calculated via formula (2).
according to formulas (1) and (2), respectively (Table 2). As reflected
in Fig. 3 triazolylglycolipids with carbon numbers of12,13, and 14 on
fatty acid possessed the most promising inhibition efficiencies of
96.9, 97.6, 97.2% (at a compound concentration of 2ꢂ10ꢁ3 M in
CH2Cl2) with 24 (C13) being most privileged. However, such variant
(P) slightly but gradually lowered when the chain length continued
to prolong (26: 96.2%, 27: 94.3%, 28: 91.8%).
Fig. 1. Electrochemical impedance spectra measured on glycolipid film covered electrode.
The self-assembled films were formed on pretreated gold elec-
trode after 2-h immersing in 2 mM triazolyl glycolipid solution in
CH2Cl2. EIS measurements were carried out in 10 e100 mHz fre-
quency range at a modified Randle’s model (Fig. 2, where Rs is the
solution resistance between the working electrode and reference
electrode; Q is the constant-phase elements; W is the Warburg
impedance) disturbed with amplitude of 5 mV controlled by elec-
trochemical software ZSimpWin. The values of charge transfer re-
sistance (Rct) were obtained from the impedance measurement and
the surface coverage (
q) and inhibition efficiency (P%) can be cal-
culated by following formulas:
Fig. 2. Equivalent circuit for the impedance spectra.
R0ct
R
ð1 ꢁ
q
Þ ¼
(1)
(2)
Fig. 3. Variation of the inhibition effect as a function of alkyl chain length.
y0corr
ꢁ
ycorr
Rct ꢁ R0ct
P% ¼
ꢂ 100 ¼
ꢂ 100
y0corr
Rct
Our preliminary result yielded by EIS measurement has dem-
onstrated the promising adsorption competence of this new tri-
azolyl glycolipid class on metal surface, which adopted a chain
length-dependent manner. This may potentially provide valuable
information toward the development of glycolipid-based green
corrosion inhibitors.
where Rct and R0ct are the charge transfer values with and without
film, respectively, for gold electrode.
Nyquist diagram of gold electrode in the presence and absence of
triazolyl glycolipids was shown in Fig. 1 and Fig. S1 (see
Supplementary data), respectively. Obviously, as listed in Table 2, the
values of Rct gradually increased when the carbon number of alkyl
group on triazole ring gradually prolonged from C5 to C13, which then
tended to decrease when the chain continuously extended (from C14
2.3. Biological assay
to C18). An obvious increase of Rct value (ΔRct¼1.181 k
U
cm2) was
observed by comparing 23 (C12) with 22 (C9) whereas a fairly regular
decrease was occurred from 25 (C13) to 28 (C18) with ΔRct values
being 0.415 (C14eC13), 0.603 (C15eC14), 0.545 (C16eC15), 0.343
Since glycolipids have previously been purposed as potential
anticancer agents possibly by inhibiting the cell proliferation pro-
cess,4 we evaluated preliminarily the cytotoxicity of compounds
20e28 on HeLa cell (cervix cancer) line by MTT assay.
(C18eC16) k
U
cm2, respectively. This experimental phenomenon
showed that the chain length preference of the protecting film at-
tachedto gold electrode was maximum 13 carbon atoms on fattyacid
while further chain elongation rendered deleterious impact.
In addition, such unique SAR was further elaborated by the cal-
As shown in Fig. 4, HeLa cells were treated with indicated
concentrations of various glycolipids (20e28) and the cell viability
was then determined by MTT assay and was expressed as mean of
three separate experiments. The IC50 values of glycolipids 23e28
culated surface coverage (q) as well as inhibition efficiency (P)
(with inhibition >50% at compound concentration of 200 mg/mL)

S.-X. Song et al. / Tetrahedron 66 (2010) 9974e9980
9977
chemistry in almost quantitative yields within only a quarter. Such
synthetic shortcut may represent a facile methodology toward the
preparation of this specific glycolipid class. Two brand new func-
tions of these newly constructed glycolipids have been sequentially
disclosed. EIS measurement indicated the potent adsorption com-
petence of this compound series on gold surface in a carbon chain
length-dependent manner, which would provide new insights to-
ward the development of triazolyl glycolipid-based green corrosion
inhibitors. In addition, the following MTT assay showed the cyto-
toxicity of the synthesized compounds on HeLa cell line howbeit
with moderate inhibitory activities. Further study including the
construction ofnewglycolipid derivatives of this kind as well as their
physiochemical and biological assessments is currently underway.
4. Experimental section
All purchased chemicals and reagents are of high commercially
available grade. Solvents were purified by standard procedures. 1H
and 13C NMR spectrum were recorded on a Bruker AM-400
spectrometer in CDCl3 or D2O solutions using tetramethylsilane as
the internal standard (chemical shifts in departs per million).
Fig. 4. Effects of the various glycolipids on the viability of HeLa cells.
Microwave-assisted reactions were performed in
a Yalian
(YL8023B1) system at 55 ꢀC with a ramp time of 2 min and hold
time of 12 min. All reactions were monitored by TLC (thin-layer
chromatography) with detection by UV or by spraying with 6 N
H2SO4 and charring at 300 ꢀC. Optical rotations were measured
using a PerkineElmer 241 polarimeter at room temperature and
a 10-cm 1-mL cell. High resolution mass spectra (HRMS) were
recorded on an MA1212 instrument using standard conditions
(ESI, 70 eV). Electrochemical experiments were carried out by
using an IM6 system (ZAHNER, Germany) controlled with analysis
software (ZSimpWin).
4.1. General procedure for the click reaction
Microwave-assisted pattern: To a well-stirred biphasic solution of
sugar azide (1 equiv) and alkynyl carboxylic ester (2 equiv) in
CH2Cl2 (4 mL) and H2O (4 mL), were added CuSO4$5H2O (0.2 equiv)
and sodium ascorbate (0.4 equiv) successively. The mixture was
then transferred to the microwave oven at 55 ꢀC for a ramp time of
2 min and hold time of 12 min. Upon completion, the resulting
mixture was diluted with CH2Cl2 (10 mL), washed with brine
(2ꢂ9 mL), dried over MgSO4 and concentrated under reduced
pressure. The crude residue was purified by column chromatogra-
phy (for conventional pattern, see Supplementary data).
Fig. 5. IC50 value of bioactive glycolipids.
were then evaluated according to the cell viability curve.20 This
result was illustrated in Fig. 5.
Evidently, the IC50 values moderately increased from 0.191 (C12
,
4.1.1. Tetra-O-benzyl-b-D-pyranoglucosyl triazolyl pentanoate (11).
compound 23) to 0.412 mM (C13, compound 24), which then
gradually decreased till 0.121 mM (C15, compound 26). However,
small increases in IC50 values were sequentially observed when the
chain length continuously prolonged (0.165e0.247 mM from C16 to
C18). Such tendency indicated that compound 26 with an alkyl
chain length of 15 carbon atoms was preferential toward inhibition
of HeLa cell line among the triazolyl glycolipids synthesized.
Indeed, triazole-contained glycolipids have been evaluated as
immunostimulating agents,2c whereas rare studies were then
revealed in relation with their potential biological profiles. There-
fore, our MTT assay performed has shown another biological ac-
tivity of triazole-linked glycolipids, which would furnish better
understanding toward the intrinsic therapeutic values of this spe-
cific compound class.
From 2 (30.7 mg, 0.22 mmol) and 1 (62 mg, 0.11 mmol), column
chromatography (petroleum ether/EtOAc, 6:1 to 4:1) afforded 11 as
a white ceraceous solid (71.9 mg, 92.9%). TLC: Rf¼0.20 (petroleum
ether/EtOAc, 4:1); [
a
]
25 ꢁ0.17 (c 0.1, CH2Cl2); 1H NMR (400 MHz,
D
CDCl3):
d
¼7.68 (s, 1H), 7.35e7.27 (m, 13H), 7.23e7.15 (m, 5H),
6.94e6.92 (m, 2H), 5.57 (d, J¼9.3 Hz, 1H), 5.20 (dd, J¼12.8 Hz,
16.4 Hz, 2H), 4.91 (dd, J¼11.0 , 12.8 Hz, 2H), 4.85 (d, J¼10.8 Hz, 1H),
4.60 (d, J¼10.8 Hz, 1H), 4.55 (d, J¼12.0 Hz, 1H), 4.49 (d, J¼12.3 Hz,
1H), 4.49 (d, J¼10.8 Hz, 1H), 4.07 (d, J¼10.8 Hz, 1H), 4.02 (t, J¼8.9 Hz,
1H), 3.82 (m, 2H), 3.73e3.67 (m, 3H), 2.30 (t, J¼7.5 Hz, 2H), 1.57 (m,
2H), 1.30 (m, 2H), 0.87 (t, J¼7.4 Hz, 3H); 13C NMR (100 MHz, CDCl3):
d¼173.3, 143.0, 138.0, 137.6, 137.5, 136.8, 128.3, 128.2, 128.1, 128.0,
127.8, 127.7, 127.6, 127.6, 127.5, 127.4, 123.0, 87.3, 85.2, 80.6, 77.9, 77.1,
75.5, 75.0, 74.7, 73.3, 68.2, 57.1, 33.6, 26.6, 22.0, 13.5; HRESIMS: calcd
for C42H47N3O7þH: 706.3492; found: 706.3488.
3. Conclusion
4.1.2. Tetra-O-benzyl-b-D-pyranoglucosyl triazolyl heptanoate (12).
In summary, we have efficiently prepared a series of novel tri-
azole-linked ester-type glycolipids via microwave accelerated click
From 3 (51.3 mg, 0.31 mmol) and 1 (86.3 mg, 0.15 mmol), column
chromatography (petroleum ether/EtOAc, 6:1 to 4:1) afforded 12 as

9978
S.-X. Song et al. / Tetrahedron 66 (2010) 9974e9980
a colorless ceraceous solid (109.4 mg, 97.7%). TLC: Rf¼0.27 (petro-
14.0; HRESIMS: calcd for
840.4560.
C
50H63N3O7þNa: 840.4564; found:
25
leum ether/EtOAc, 4:1); [
(400 MHz, CDCl3):
a]
ꢁ19.5 (c 0.2, CH2Cl2); 1H NMR
D
d¼7.68 (s, 1H), 7.34e7.28 (m, 13H), 7.23e7.16 (m,
5H), 6.94e6.92 (m, 2H), 5.57 (d, J¼9.0 Hz, 1H), 5.20 (dd, J¼12.8 ,
16.8 Hz, 2H), 4.92 (dd, J¼11.2 , 12.8 Hz, 2H), 4.85 (d, J¼10.8 Hz, 1H),
4.60 (d, J¼10.8 Hz, 1H), 4.55 (d, J¼12.3 Hz, 1H), 4.49 (d, J¼12.5 Hz,
1H), 4.49 (d, J¼10.8 Hz, 1H), 4.07 (d, J¼10.5 Hz, 1H), 4.02
(t, J¼8.9 Hz, 1H), 3.82 (m, 2H), 3.73e3.67 (m, 3H), 2.29 (t, J¼7.5 Hz,
2H), 1.58 (m, 2H), 1.31e1.20 (br m, 6H), 0.86 (t, J¼6.9 Hz, 3H); 13C
4.1.6. Tetra-O-benzyl-b-D-pyranoglucosyl triazolyl tetradecanoate(16).
From 7 (48.1 mg, 0.18 mmol) and 1 (51.1 mg, 0.09 mmol), column
chromatography (petroleum ether/EtOAc, 6:1 to 4:1) afforded 16 as
a white ceraceous solid (73.9 mg, 98.3%). TLC: Rf¼0.29 (petroleum
ether/EtOAc, 4:1); [
a
]
25 ꢁ20.4 (c 0.1, CH2Cl2); 1H NMR (400 MHz,
D
CDCl3):
d
¼7.68 (s, 1H), 7.34e7.27 (m, 13H), 7.22e7.16 (m, 5H),
NMR (100 MHz, CDCl3):
d
¼173.4, 143.0, 138.0, 137.6, 137.6, 136.8,
6.94e6.92 (m, 2H), 5.57 (d, J¼9.0 Hz, 1H), 5.20 (dd, J¼12.8 , 16.4 Hz,
2H), 4.91 (dd, J¼11.2 , 12.8 Hz, 2H), 4.85 (d, J¼10.8 Hz, 1H), 4.60 (d,
J¼10.8 Hz, 1H), 4.55 (d, J¼12.3 Hz, 1H), 4.49 (d, J¼12.5 Hz, 1H), 4.49
(d, J¼10.5 Hz, 1H), 4.07 (d, J¼10.5 Hz, 1H), 4.02 (t, J¼8.8 Hz, 1H), 3.82
(m, 2H), 3.73e3.67 (br m, 3H), 2.29 (t, J¼7.5 Hz, 2H), 1.58 (br m, 2H),
1.30e1.24 (br m, 20H), 0.88 (t, J¼6.8 Hz, 3H); 13C NMR (100 MHz,
128.3, 128.3, 128.2, 128.1, 127.8, 127.8, 127.7, 127.6, 127.6, 127.5, 123.0,
87.4, 85.3, 80.6, 77.9, 77.1, 75.6, 75.0, 74.7, 73.4, 68.2, 57.2, 33.9, 31.2,
28.6, 24.6, 22.3, 13.9; HRESIMS: calcd for C44H51N3O7þH: 734.3085;
found: 734.3082.
4.1.3. Tetra-O-benzyl-
b
-D
-pyranoglucosyl triazolyl nonanoate (13).
CDCl3):
d¼173.4, 143.1, 138.0, 137.6, 137.6, 136.8, 128.3, 128.3, 128.2,
From 4 (41.9 mg, 0.21 mmol) and 1 (60.4 mg, 0.11 mmol), column
chromatography (petroleum ether/EtOAc, 6:1 to 4:1) afforded 13 as
a white ceraceous solid (80.6 mg, 99.0%). TLC: Rf¼0.34 (petroleum
128.1,127.9,127.8,127.7,127.7,127.6,127.6,123.0, 87.4, 85.3, 80.6, 78.0,
77.1, 75.6, 75.1, 74.8, 73.4, 68.2, 57.2, 34.0, 31.8, 29.5, 29.5, 29.5, 29.3,
29.2, 29.1, 29.0, 24.7, 22.6, 14.0; HRESIMS: calcd for C51H65N3O7þNa:
854.4720; found: 854.4719.
ether/EtOAc, 4:1); [
a
]
25ꢁ15.1 (c 0.07, CH2Cl2); 1H NMR (400 MHz,
D
CDCl3):
d¼7.68 (s, 1H), 7.34e7.27 (m, 13H), 7.22e7.16 (m, 5H),
6.94e6.92 (m, 2H), 5.57 (d, J¼9.0 Hz, 1H), 5.20 (dd, J¼12.8 Hz,
16.8 Hz, 2H), 4.92 (dd, J¼11.2 , 12.8 Hz, 2H), 4.85 (d, J¼10.5 Hz, 1H),
4.60 (d, J¼10.5 Hz, 1H), 4.55 (d, J¼12.0 Hz, 1H), 4.49 (d, J¼12.5 Hz,
1H), 4.49 (d, J¼10.5 Hz,1H), 4.07 (d, J¼10.5 Hz,1H), 4.02 (t, J¼8.8 Hz,
1H), 3.82 (m, 2H), 3.73e3.68 (m, 3H), 2.29 (t, J¼7.5 Hz, 2H), 1.58 (m,
2H),1.30e1.24 (br m,10H), 0.87 (t, J¼6.9 Hz, 3H); 13C NMR (100 MHz,
4.1.7. Tetra-O-benzyl-b-D-pyranoglucosyl triazolyl pentadecanoate (17).
From 8 (49.8 mg, 0.18 mmol) and 1 (50.2 mg, 0.09 mmol), column
chromatography (petroleum ether/EtOAc, 6:1 to 4:1) afforded 17 as
a white ceraceous solid (72.2 mg, 96.1%). TLC: Rf¼0.35 (petroleum ether/
EtOAc, 4:1); [a]D25þ20.0(c0.1, CH2Cl2); 1H NMR (400 MHz, CDCl3):
¼7.68
d
(s,1H), 7.34e7.28 (m,13H), 7.22e7.14(m, 5H), 6.93e6.91 (m, 2H), 5.57 (d,
J¼9.0 Hz, 1H), 5.20 (dd, J¼12.8 Hz, 16.8 Hz, 2H), 4.92 (dd, J¼11.0 Hz,
12.8 Hz, 2H), 4.85 (d, J¼10.5 Hz, 1H), 4.59 (d, J¼10.8 Hz, 1H), 4.55 (d,
J¼12.0 Hz, 1H), 4.49 (d, J¼10.8 Hz, 2H), 4.07 (d, J¼10.8 Hz, 1H), 4.03 (t,
J¼8.9 Hz, 1H), 3.82 (m, 2H), 3.71e3.68 (br m, 3H), 2.28 (t, J¼7.7 Hz, 2H),
1.57 (br m, 2H), 1.33e1.28 (br m, 2H), 1.24 (d, J¼5.3 Hz, 20H), 0.88 (t,
CDCl3):
d
¼173.4, 143.0, 137.9, 137.6, 137.5, 136.8, 128.3, 128.3, 128.2,
128.1,127.8,127.8,127.7,127.7,127.6,127.5,123.1, 87.3, 85.3, 80.5, 77.9,
77.0, 75.6, 75.0, 74.7, 73.3, 68.1, 57.2, 33.9, 31.6, 29.0, 28.9, 28.9, 24.6,
22.5, 14.0; HRESIMS: calcd for C46H55N3O7þNa: 784.3938; found:
784.3941.
J¼6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3):
¼173.5, 143.0, 138.0, 137.6,
d
4.1.4. Tetra-O-benzyl-
b
-D
-pyranoglucosyl triazolyl dodecanoate (14).
137.5,136.8,128.4,128.3,128.2,128.1,127.9,127.8,127.7,127.7,127.7,127.6,
123.1, 87.3, 85.3, 80.5, 77.9, 77.0, 75.6, 75.1, 74.8, 73.4, 68.1, 57.2, 34.0, 31.8,
29.6, 29.6, 29.5, 29.5, 29.3, 29.2, 29.1, 29.0, 24.7, 22.6, 14.0; HRESIMS:
C52H67N3O7þNa: calcd for 868.4877; found: 868.4876.
From 5 (42.9 mg, 0.18 mmol) and 1 (51.0 mg, 0.09 mmol), column
chromatography (petroleum ether/EtOAc, 6:1 to 4:1) afforded 13 as
a white ceraceous solid (70.0 mg, 96.6%). TLC: Rf¼0.29 (petroleum
ether/EtOAc, 4:1); [
CDCl3):
a
]
25ꢁ42.4 (c 0.2, CH2Cl2); 1H NMR (400 MHz,
D
d
¼7.68 (s, 1H), 7.34e7.27 (m, 13H), 7.22e7.16 (m, 5H),
4.1.8. Tetra-O-benzyl-b-D-pyranoglucosyl triazolyl palmitate (18).
6.94e6.92 (m, 2H), 5.57 (d, J¼9.0 Hz, 1H), 5.20 (dd, J¼12.8 , 16.4 Hz,
2H), 4.92 (dd, J¼11.0 , 12.8 Hz, 2H), 4.85 (d, J¼10.8 Hz, 1H), 4.60 (d,
J¼10.8 Hz, 1H), 4.55 (d, J¼12.0 Hz, 1H), 4.49 (d, J¼12.8 Hz, 1H), 4.49
(d, J¼10.5 Hz,1H), 4.07 (d, J¼10.8 Hz,1H), 4.02 (t, J¼8.8 Hz,1H), 3.82
(m, 2H), 3.73e3.67 (br m, 3H), 2.29 (t, J¼7.5 Hz, 2H), 1.58 (br m, 2H),
1.32e1.24 (br m, 16H), 0.88 (t, J¼6.8 Hz, 3H); 13C NMR (100 MHz,
From compound 9 (46.8 mg, 0.16 mmol) and 1 (45 mg, 0.08 mmol),
column chromatography (petroleum ether/EtOAc, 8:1 to 4:1)
afforded 18 as a white ceraceous solid (66.1 mg, 96.6%). TLC:
Rf¼0.31 (petroleum ether/EtOAc, 4:1); [
a
]
2D5ꢁ8.0 (c 0.2, CH2Cl2); 1H
NMR (400 MHz, CDCl3):
d
¼7.68 (s, 1H), 7.36e7.28 (m, 13H),
7.21e7.15 (m, 5H), 6.94e6.91 (m, 2H), 5.57 (d, J¼9.0 Hz, 1H), 5.20
(dd, J¼12.9 , 16.4 Hz, 2H), 4.92 (dd, J¼11.3 , 12.8 Hz, 2H), 4.85 (d,
J¼10.8 Hz, 1H), 4.60 (d, J¼10.8 Hz, 1H), 4.55 (d, J¼12.0 Hz, 1H), 4.49
(d, J¼12.3 Hz, 2H), 4.07 (d, J¼10.5 Hz, 1H), 4.02 (t, J¼8.8 Hz, 1H),
3.82 (m, 2H), 3.72e3.68 (br m, 3H), 2.28 (t, J¼7.5 Hz, 2H), 1.57 (br m,
2H), 1.32e1.28 (br m, 2H), 1.25 (d, J¼6.3 Hz, 22H), 0.88 (t, J¼6.7 Hz,
CDCl3):
d
¼173.4, 143.0, 138.0, 137.6, 136.8, 128.3, 128.3, 128.2, 128.1,
127.8, 127.8, 127.7, 127.6, 127.5, 123.0, 87.4, 85.3, 80.6, 77.9, 77.1, 75.6,
75.0, 74.7, 73.4, 68.2, 57.2, 33.9, 31.7, 29.4, 29.3, 29.2, 29.1, 29.0, 24.7,
22.5, 14.0; HRESIMS: calcd for C49H61N3O7þH: 804.4588; found:
804.4583.
3H); 13C NMR (100 MHz, CDCl3):
d¼173.4, 143.0, 138.0, 137.6, 137.6,
4.1.5. Tetra-O-benzyl-
b
-D
-pyranoglucosyl triazolyl tridecanoate (15).
136.8, 128.3, 128.3, 128.2, 128.1, 127.8, 127.8, 127.7, 127.7, 127.6, 127.5,
123.0, 87.4, 85.3, 80.6, 77.9, 77.1, 75.6, 75.0, 74.8, 73.4, 68.2, 57.2,
34.0, 31.8, 29.6, 29.5, 29.5, 29.5, 29.3, 29.2, 29.1, 29.0, 24.7, 22.6,14.0;
HRESIMS: C53H69N3O7þNa: calcd for 882.5033; found: 882.5037.
From 6 (41.9 mg, 0.17 mmol) and 1 (47 mg, 0.08 mmol), column
chromatography (petroleum ether/EtOAc, 6:1 to 4:1) afforded 15 as
a white ceraceous solid (65.6 mg, 96.5%). TLC: Rf¼0.35 (petroleum
ether/EtOAc, 4:1); [
a
]
25ꢁ19.4 (c 0.1, CH2Cl2); 1H NMR (400 MHz,
D
CDCl3):
d
¼7.68 (s, 1H), 7.34e7.28 (m, 13H), 7.21e7.15 (m, 5H),
4.1.9. Tetra-O-benzyl-b-D-pyranoglucosyl triazolyl stearate (19).
6.94e6.92 (m, 2H), 5.57 (d, J¼9.0 Hz, 1H), 5.20 (dd, J¼12.9 , 16.8 Hz,
2H), 4.92 (dd, J¼11.3 , 12.8 Hz, 2H), 4.85 (d, J¼10.8 Hz, 1H), 4.60 (d,
J¼10.8 Hz, 1H), 4.55 (d, J¼12.0 Hz, 1H), 4.49 (d, J¼12.3 Hz, 2H), 4.07
(d, J¼10.5 Hz, 1H), 4.02 (t, J¼8.8 Hz, 1H), 3.82 (m, 2H), 3.72e3.68 (br
m, 3H), 2.29 (t, J¼7.7 Hz, 2H), 1.57 (br m, 2H), 1.32e1.24 (br m, 18H),
From compound 10 (69.6 mg, 0.22 mmol) and 1 (61 mg, 0.11 mmol),
column chromatography (petroleum ether/EtOAc, 10:1 to 4:1)
afforded 19 as a white ceraceous solid (94.1 mg, 98.3%). TLC: Rf¼0.30
(petroleum ether/EtOAc, 4:1); [
a]
D
25ꢁ9.21 (c 0.2, CH2Cl2); 1H NMR
(400 MHz, CDCl3):
d
¼7.68 (s, 1H), 7.33e7.28 (m, 13H), 7.21e7.16 (m,
0.88 (t, J¼6.8 Hz, 3H); 13C NMR (100 MHz, CDCl3):
d¼173.5, 143.1,
5H), 6.94e6.92 (m, 2H), 5.57 (d, J¼9.0 Hz, 1H), 5.20 (dd, J¼12.8 Hz,
16.4 Hz, 2H), 4.92 (dd, J¼11.3 , 13.0 Hz, 2H), 4.85 (d, J¼10.8 Hz, 1H),
4.60 (d, J¼10.8 Hz, 1H), 4.55 (d, J¼12.0 Hz, 1H), 4.49 (d, J¼12.3 Hz,
2H), 4.07 (d, J¼10.5 Hz, 1H), 4.03 (t, J¼8.9 Hz, 1H), 3.82 (m, 2H),
138.0, 137.6, 137.6, 136.8, 128.4, 128.3, 128.2, 128.1, 127.9, 127.8, 127.7,
127.7, 127.7, 127.6, 123.1, 87.4, 85.3, 80.6, 80.0, 77.1, 75.7, 75.1, 74.8,
73.4, 68.2, 57.2, 34.0, 31.8, 29.5, 29.5, 29.3, 29.2, 29.1, 29.0, 24.7, 22.6,

S.-X. Song et al. / Tetrahedron 66 (2010) 9974e9980
9979
3.72e3.68 (br m, 3H), 2.29 (t, J¼7.7 Hz, 2H),1.58 (br m, 2H),1.34e1.28
(br m, 2H), 1.25 (d, J¼6.3 Hz, 26H), 0.88 (t, J¼6.8 Hz, 3H); 13C NMR
EtOH,12:1 to 8:1) afforded 24 as a white solid (77.6 mg, 84.4%). TLC:
Rf¼0.63 (EtOAc/MeOH, 4:1); [
a
]
25ꢁ6.57 (c 0.4, CH3OH); 1H NMR
D
(100 MHz, CDCl3):
d
¼173.5, 143.1, 138.0, 137.6, 137.6, 136.8, 128.4,
(400 MHz, CDCl3):
d
¼7.98 (s, 1H), 5.56 (d, J¼9.0 Hz,1H), 5.05 (s, 2H),
128.3, 128.3, 128.1, 127.9, 127.9, 127.7, 127.7, 127.7, 127.6, 123.1, 87.4,
85.4, 80.6, 78.0, 77.1, 75.7, 75.1, 74.8, 73.4, 68.2, 57.3, 34.0, 31.8, 29.6,
29.6, 29.6, 29.5, 29.4, 29.3, 29.1, 29.0, 24.7, 22.6, 14.1; HRESIMS:
C55H73N3O7þNa: calcd for 910.5346; found: 910.5341.
3.95 (t, J¼8.3 Hz, 1H), 3.77e3.71 (br m, 2H), 3.70e3.65 (br m, 2H),
3.56 (br s, 1H), 2.25 (t, J¼7.7 Hz, 2H), 1.54 (br m, 2H), 1.24 (br s, 18H),
0.87 (t, J¼6.8 Hz, 3H); 13C NMR (100 MHz, CDCl3):
¼173.9, 142.7,
d
124.7, 87.6, 78.8, 76.4, 72.3, 68.7, 60.7, 56.9, 33.9, 31.9, 29.7, 29.7,
29.6, 29.5, 29.3, 29.2, 24.7, 22.6, 14.0; HRESIMS: calcd for:
C22H39N3O7þH: 458.2866; found: 458.2861.
4.2. General procedure for the debenzylation
To a solution of benzylated glycolipids in MeOH (8e16 mL) was
added PdCl2 (0.5 equiv), stirring vigorously under hydrogen at-
mosphere for 20 min. After which, the hydrogen gas was released
rapidly and the system was refilled with H2 again. This manipula-
tion was repeated thrice. The resulting mixture was then filtered
and concentrated under reduced pressure to give the crude residue,
which was purified by column chromatography.
4.2.6. b-D-Pyranoglucosyl triazolyl tetradecanoate (25). From com-
pound 16 (273 mg, 0.328 mmol), column chromatography (EtOAc/
EtOH, 12:1 to 8:1) afforded 25 as a white solid (111.8 mg, 72.3%).
TLC: Rf¼0.60 (EtOAc/MeOH, 4:1); [
a
]
25 ꢁ3.01 (c 0.3, CH3OH); 1H
D
NMR (400 MHz, CDCl3):
d
¼7.98 (s, 1H), 5.55 (d, J¼8.8 Hz, 1H), 5.04
(s, 2H), 3.93 (t, J¼8.8 Hz, 1H), 3.75e3.67 (br m, 2H), 3.66e3.59 (br
m, 2H), 3.55 (br s, 1H), 2.24 (t, J¼7.5 Hz, 2H), 1.54 (br m, 2H), 1.24 (br
s, 20H), 0.87 (t, J¼6.8 Hz, 3H); 13C NMR (100 MHz, CDCl3þCD3OD):
4.2.1.
b-
D-Pyranoglucosyl triazolyl heptanoate (20). From11 (311 mg,
d
¼173.9,142.5, 124.1, 87.6, 78.9, 76.4, 72.3, 68.7, 60.7, 56.9, 33.8, 31.7,
0.441 mmol), column chromatography (EtOAc/EtOH, 12:1 to 6:1)
29.5, 29.5, 29.5, 29.3, 29.2, 29.1, 29.0, 24.6, 22.5, 13.9; HRESIMS:
afforded 20 as a colorless solid (137.7 mg, 90.5%). TLC: Rf¼0.42
calcd for: C23H41N3O7þH: 472.3023; found: 472.3020.
(EtOAc/MeOH, 4:1); [
a
]
2D5ꢁ1.93 (c 0.30, CH3OH); 1H NMR (400 MHz,
CDCl3):
d
¼8.10 (s, 1H), 5.61 (d, J¼9.3 Hz, 1H), 5.08 (s, 2H), 3.91 (t,
4.2.7. b-D-Pyranoglucosyl triazolyl tetradecanoate (26). From com-
pound 17 (303 mg, 0.359 mmol), column chromatography (EtOAc/
EtOH, 12:1 to 8:1) afforded 26 as a white solid (157.8 mg, 90.6%).
J¼8.9 Hz, 1H), 3.77e3.72 (m, 1H), 3.70e3.65 (m, 1H), 3.63e3.54 (m,
3H), 2.24 (t, J¼7.5 Hz, 2H),1.46 (m, 2H),1.20 (m, 2H), 0.78 (t, J¼7.3 Hz,
3H); 13C NMR (100 MHz, CDCl3þCD3OD):
d¼173.9,142.6,124.3, 87.6,
TLC: Rf¼0.51 (EtOAc/MeOH, 4:1); [
a
]
2D5ꢁ2.0 (c 0.3, CH3OH); 1H NMR
78.8, 76.4, 72.3, 68.8, 60.7, 56.9, 33.5, 26.6, 21.9,13.4; HRESIMS: calcd
(400 MHz, CDCl3):
d
¼7.98 (s,1H), 5.55 (d, J¼8.8 Hz,1H), 5.04 (s, 2H),
for: C14H23N3O7þH: 346.1614; found: 346.1616.
3.93 (t, J¼8.7 Hz, 1H), 3.73e3.68 (br m, 2H), 3.67e3.60 (br m, 2H),
3.55 (br s, 1H), 2.25 (t, J¼7.5 Hz, 2H), 1.54 (br m, 2H), 1.24 (br s, 22H),
4.2.2.
b-D
-Pyranoglucosyl triazolyl pentanoate (21). From compound
0.87 (t, J¼6.9 Hz, 3H); 13C NMR (100 MHz, CDCl3):
¼173.8, 142.6,
d
12 (304 mg, 0.414 mmol), column chromatography (EtOAc/EtOH,
12:1 to 8:1) afforded 21 as a colorless solid (143.1 mg, 92.5%). TLC:
124.6, 87.6, 78.8, 76.4, 72.3, 68.7, 60.8, 56.9, 33.9, 31.9, 29.1, 29.6,
29.6, 29.5, 29.3, 29.1, 29.0, 24.7, 22.6, 14.0; HRESIMS: calcd for:
C24H43N3O7þH: 486.3179; found: 486.3177.
Rf¼0.48 (EtOAc/MeOH, 4:1); [
a
]
25ꢁ2.36 (c 0.3, CH3OH); 1H NMR
D
(400 MHz, CDCl3):
d
¼8.01 (s,1H), 5.56 (d, J¼8.8 Hz,1H), 5.07 (s, 2H),
3.90 (t, J¼8.2 Hz, 1H), 3.77e3.67 (m, 2H), 3.64e3.56 (m, 3H), 2.23 (t,
4.2.8. b-D-Pyranoglucosyl triazolyl palmitate (27). From compound
18 (251 mg, 0.292 mmol), column chromatography (EtOAc/EtOH,
12:1 to 8:1) afforded 27 as a white solid (109.5 mg, 75.1%). TLC:
J¼7.4 Hz, 2H), 1.51 (m, 2H), 1.20 (br s, 6H), 0.80 (t, J¼6.5 Hz, 3H); 13C
NMR (100 MHz, CDCl3þCD3OD): ¼174.0, 142.6, 124.4, 87.6, 78.9,
d
76.3, 72.3, 68.8, 60.7, 56.9, 33.9, 31.2, 28.6, 24.5, 22.3, 13.8; HRE-
Rf¼0.59 (EtOAc/MeOH, 4:1); [
a
]
25 ꢁ18.8 (c 0.1, CH3OH); 1H NMR
D
SIMS: calcd for: C16H27N3O7þH: 374.1927; found: 374.1925.
(400 MHz, CDCl3):
d
¼7.98 (s,1H), 5.55 (d, J¼9.0 Hz,1H), 5.04 (s, 2H),
3.93 (t, J¼8.5 Hz, 1H), 3.75e3.68 (br m, 2H), 3.66e3.60 (br m, 2H),
3.55 (br s, 1H), 2.24 (t, J¼7.5 Hz, 2H), 1.54 (br m, 2H), 1.24 (br s, 24H),
4.2.3.
b-D-Pyranoglucosyl triazolyl nonanoate (22). From compound
13 (165 mg, 0.216 mmol), column chromatography (EtOAc/EtOH,
12:1 to 8:1) afforded 22 as a colorless solid (83.7 mg, 96.5%). TLC:
0.87 (t, J¼6.5 Hz, 3H); 13C NMR (100 MHz, CDCl3þCD3OD):
¼173.9,
d
142.7, 124.7, 87.6, 78.7, 76.3, 72.3, 68.6, 60.6, 56.9, 34.0, 31.9, 29.7,
29.7, 29.4, 29.2, 29.1, 24.7, 22.7, 14.1; HRESIMS: calcd for:
C25H45N3O7þH: 500.3336; found: 500.3333.
Rf¼0.67 (EtOAc/MeOH, 4:1); [
a
]
25ꢁ0.90 (c 0.3, CH3OH); 1H NMR
D
(400 MHz, CDCl3):
d
¼8.00 (s, 1H), 5.56 (d, J¼8.3 Hz, 1H), 5.03 (s,
2H), 3.97 (t, J¼8.2 Hz, 1H), 3.74e3.67 (br m, 2H), 3.62e3.55 (br m,
3H), 2.24 (t, J¼7.0 Hz, 2H), 1.53 (br m, 2H), 1.23 (br s, 10H), 0.85 (t,
4.2.9.
b-D-Pyranoglucosyl triazolyl stearate (28). From compound
J¼6.8 Hz, 3H); 13C NMR (100 MHz, CDCl3þCD3OD):
d¼173.9, 142.7,
19 (255 mg, 0.287 mmol), column chromatography (EtOAc/EtOH,
12:1 to 8:1) afforded 28 as a white solid (129.4 mg, 85.5%). TLC:
124.7, 87.6, 78.8, 76.3, 72.4, 68.8, 60.7, 57.0, 33.9, 31.8, 29.2, 29.1,
24.7, 22.6, 14.0; HRESIMS: calcd for: C18H31N3O7þH: 402.2240;
found: 402.2241.
Rf¼0.57 (EtOAc/MeOH, 4:1); [
a
]
25 ꢁ1.90 (c 0.1, CH3OH); 1H NMR
D
(400 MHz, CDCl3):
d
¼7.94 (s,1H), 5.56 (d, J¼9.0 Hz,1H), 5.06 (s, 2H),
4.06 (t, J¼8.5 Hz, 1H), 3.80e3.71 (br m, 4H), 3.59 (br s, 1H), 2.25 (t,
J¼7.5 Hz, 2H), 1.55 (br m, 2H), 1.25 (br s, 28H), 0.88 (t, J¼6.8 Hz, 3H);
4.2.4.
b-D-Pyranoglucosyl triazolyl dodecanoate (23). From com-
pound 14 (286 mg, 0.356 mmol), column chromatography (EtOAc/
EtOH, 12:1 to 8:1) afforded 23 as a colorless solid (104.3 mg, 66.1%).
13C NMR (100 MHz, CDCl3þCD3OD):
¼173.9, 142.6, 124.0, 87.8,
d
79.0, 77.2, 72.4, 68.9, 61.0, 56.9, 33.9, 31.7, 29.5, 29.5, 29.4, 29.3, 29.2,
29.1, 29.0, 24.6, 22.5, 13.9; HRESIMS: calcd for: C27H49N3O7þH:
528.3649; found: 528.3646.
TLC: Rf¼0.65 (EtOAc/MeOH, 4:1); [
a
]
25 ꢁ0.78 (c 0.2, CH3OH); 1H
D
NMR (400 MHz, CDCl3):
d
¼7.99 (s, 1H), 5.55 (d, J¼9.0 Hz, 1H), 5.03
(s, 2H), 3.92 (t, J¼8.9 Hz, 1H), 3.75e3.66 (br m, 2H), 3.66e3.59 (br
m, 2H), 3.54 (br s, 1H), 2.24 (t, J¼7.5 Hz, 2H), 1.53 (br m, 2H), 1.24 (br
s, 16H), 0.86 (t, J¼6.7 Hz, 3H); 13C NMR (100 MHz, CDCl3þCD3OD):
4.3. EIS measurement
d
¼173.9,142.4, 124.1, 87.6, 78.9, 76.4, 72.3, 68.7, 60.7, 56.8, 33.8, 31.7,
The gold electrode (1.0 mm radius) was polished first mechan-
ically with alumina powder slurry (0.3 down to 0.05) on a polish
cloth, sonicated in water baths for 5 min to remove any physically
adsorbed species, then electrochemically by cycling the electrode
potential from 0.0 to þ1.6 V versus SCE in 0.5 M H2SO4 until re-
producible cyclic voltammograms were obtained. The electrode
29.4, 29.2, 29.1, 29.1, 28.9, 24.5, 22.4, 13.8; HRESIMS: calcd for
C21H37N3O7þH: 444.2710; found: 444.2703.
4.2.5.
b-D-Pyranoglucosyl triazolyl tridecanoate (24). From com-
pound 15 (164 mg, 0.201 mmol), column chromatography (EtOAc/

9980
S.-X. Song et al. / Tetrahedron 66 (2010) 9974e9980
was sequentially rinsed with double-distilled water rapidly, fol-
lowed by rinsing with absolute ethanol as soon as possible and
immersed in 2 mM triazolyl glycolipid solutions in CH2Cl2 for 2 h to
form self-assembled film. After completion of the film formation,
the electrodes were taken out rinsed with absolute ethanol and
double-distilled water.
Supplementary data
Supplementary data associated with this article can be found in
the online version at doi:10.1016/j.tet.2010.10.033.
References and notes
Electrochemical experiments were performed in
a three
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Acknowledgements
This project was supported by National Natural Science Foun-
dation of China (Grant No. 20876045), National Science & Tech-
nology Major Project of China ‘Key New Drug Creation and
Manufacturing Program’ (No. 2009ZX09302-001), Shanghai Sci-
ence and Technology Community (No. 10410702700, 08DZ2291300
and 09DZ2291200), and Chinese Academy of Sciences (No. KSCX2-
YW-R-168). X.-P. He also gratefully acknowledges the French Em-
bassy for the financial support of a co-tutored doctoral program as
well as his French advisor Prof. J. Xie (ENS Cachan).
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