FeCl3.6H2O/C: An Efficient and Recyclable Catalyst for the Synthesis of 2,3-Unsaturated O-and S-Glycosides

Article abstract of DOI:10.1080/07328303.2014.941995

A novel method for synthesizing 2,3-unsaturated glycosides has been developed using a handy and eco-friendly immobilized catalyst, FeCl₃.6H₂O/C. A series of 2,3-unsaturated O-and S-glycosides were obtained for bioassay from corresponding 3,4,6-tri-O-acetyl-D-glucal and D-galactal in good to excellent yields (56%-99%) and high anomeric selectivity (α/β = 7:1 to >19:1). Furthermore, the catalyst was efficient on gram-scale reactions and recyclable for at least three times.

Full text of DOI:10.1080/07328303.2014.941995

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FeCl ·6H O/C: An Efficient and
3
2
Recyclable Catalyst for the Synthesis of
,3-Unsaturated O- and S-Glycosides
a
2
a
a
b
a
Jiafen Zhou , Heshan Chen , Junjie Shan , Juan Li , Guofang Yang ,
a
a
a
a
Xuan Chen , Kunyun Xin , Jianbo Zhang & Jie Tang
a
Department of Chemistry, East China Normal University, Shanghai
00241, China
2
b
Beijing Institute of Pharmacology and Toxicology, Beijing 100850,
China
Published online: 08 Aug 2014.
To cite this article: Jiafen Zhou, Heshan Chen, Junjie Shan, Juan Li, Guofang Yang, Xuan Chen,
Kunyun Xin, Jianbo Zhang & Jie Tang (2014) FeCl ·6H O/C: An Efficient and Recyclable Catalyst for
3
2
the Synthesis of 2,3-Unsaturated O- and S-Glycosides, Journal of Carbohydrate Chemistry, 33:6,
13-325, DOI: 10.1080/07328303.2014.941995
3
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Journal of Carbohydrate Chemistry, 33:313–325, 2014
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 0732-8303 print / 1532-2327 online
DOI: 10.1080/07328303.2014.941995
FeCl ·6H O/C: An Efficient and
3
2
Recyclable Catalyst for the
Synthesis of 2,3-Unsaturated
O- and S-Glycosides
1
1
2
1
Jiafen Zhou, Heshan Chen, Junjie Shan, Juan Li,
1
1
1
1
Guofang Yang, Xuan Chen, Kunyun Xin, Jianbo Zhang,
and Jie Tang1
1
Department of Chemistry, East China Normal University, Shanghai 200241, China
Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
2
A novel method for synthesizing 2,3-unsaturated glycosides has been developed using a
handy and eco-friendly immobilized catalyst, FeCl O/C. A series of 2,3-unsaturated
3
·6H
2
O- and S-glycosides were obtained for bioassay from corresponding 3,4,6-tri-O-acetyl-D-
glucal and D-galactal in good to excellent yields (56%–99%) and high anomeric selectiv-
ity (α/β = 7:1 to >19:1). Furthermore, the catalyst was efficient on gram-scale reactions
and recyclable for at least three times.
Keywords
Ferrier-rearrangement; Recyclable
FeCl
3
·6H
2
O/C; Tri-O-acetyl-D-glycals; 2,3-Unsaturated glycosides;
INTRODUCTION
2
,3-Unsaturated glycosides as chiral intermediates have played an impor-
[
1]
tant role in the synthesis of bioactive compounds, such as oligosaccharides,
[
2]
[3]
[4]
glycopeptide building blocks, modified carbohydrates, nucleosides, and
antibiotics.[ Besides, the unsaturated part of the sugar ring allows many
straightforward modifications such as hydroxylation, oxidation, epoxidation,
and hydrogenation, which contributes to their diversity and complexity.[6–11]
As we know, the most valuable method for preparing 2,3-unsaturated gly-
5]
cosides is Lewis acid–catalyzed allelic rearrangement of glycals, which is
well known as the Ferrier rearrangement reaction.[
12,13]
Up to now, a wide
[
12]
[14]
range of Lewis acids and oxidizing agents, such as BF3·OEt2,
IDCP,
Received May 8, 2014; accepted July 2, 2014.
Address correspondence to Jianbo Zhang, Department of Chemistry, East China Nor-
mal University, Shanghai 200241, China. E-mail: jbzhang@chem.ecnu.edu.cn
3
13

14 J. Zhou et al.
3
Table 1: Optimization of reaction conditions for the synthesis of 2,3-unsaturated
glucosides
Entry
Conditions
Yield (%)
1
2
3
4
5
FeCl3·6H
2
O/C (0.01eq), 240min
45
95
99
98
80
FeCl3·6H
FeCl3·6H
FeCl3·6H
2
O/C (0.02eq), 40min
O/C (0.05eq), 10min
O/C (0.05eq), 10min
2
2
FeCl3·6H
2
O/SiO
2
(0.05eq), 120min
6
FeCl3·6H
2
O/4 ÅMS (0.05eq), 120min
traces
TMSOTf,[15] I2,[16] Sc(OTf)3,
[17]
InCl3,
[18]
Yb(OTf)3,[19] BiCl3,[20] Dy(OTf)3 im-
[
21]
[22]
[23]
[224]
[25]
mobilized in ionic liquids,
ZnCl2,
HClO4-SiO2,
NiCl5,
Er(OTf)3,
[
26]
[27]
[28]
[29]
ZnCl2/Al2O3,
H2SO4-SiO2,
NaHSO4-SiO2,
and CF3SO3H-SiO2,
have
been employed for this transformation. However, the present methods for the
synthesis of 2,3-unsaturated glycosides possess some drawbacks, such as use
of expensive and toxic reagents and/or stoichiometric amount of catalyst, low
efficiency, and complicated operation.
Recently, iron (III) catalysts have been widely used in organic syn-
thesis,[
30,31]
and some of these types of catalysts, such as FeCl3,
[32]
[35]
[33]
[34]
Fe2(SO4)3·xH2O,
FeCl3 immobilized in ionic liquids,
and Fe(OTf)3,
have been successfully utilized for the Ferrier rearrangement. In our previous
research for diverse syntheses of glycosides, we have successfully used im-
mobilized catalysts for Ferrier rearrangement.[
27,36]
The present work aimed
at developing a new and reusable immobilized iron (III) catalyst for Ferrier
rearrangement.
Initially, we screened different carriers, including carbon, SiO2, and molec-
ular sieves, to immobilize iron (III) chloride hexahydrate (FeCl3·6H2O) ac-
[
37,38]
cording to the literature method.
We found that FeCl3·6H2O/C was the
most promising for catalyzing the reaction between 3,4,6-tri-O-acetyl-D-glucal
and benzyl alcohol, because other immobilized iron (III) catalysts, including
˚
FeCl3·6H2O/SiO2 and FeCl3·6H2O/4 AMS, could only give the desired product
either in longer time or poorer yield (Table 1). Therefore, FeCl3·6H2O/C was
explored in detail to establish the proper reaction conditions. We found that
0
.05 equiv FeCl3·6H2O/C was sufficient to promote the reaction and gave an
excellent yield (99%) in 10 min at rt using CH2Cl2 as solvent. When a smaller
amount of catalyst was used, the reaction preceded much slower, while the
reaction rate and yield were not improved with a larger amount of catalyst.
With the optimal conditions established, we next investigated the reac-
tion scope using a variety of acceptors. As shown in Table 2, glycosidation of

FeCl
3
·6H
2
O/C
3
15
Table 2: Ferrier reaction of 3, 4, 6-tri-O-acetyl-D-glycal with acceptors in the
presence of the FeCl O/C reagent system
•6H
3
2
α/β
Time
(h)
Yield
a
ratiosb
Entry
1
Acceptors
Products
(%)
CH
3
(CH
2
)CH
2
OH
2
1.5
93[36]
7.5:1
1
a
2
3
1.5
1.5
93[40]
97[25]
>19:1
CH
3
(CH
2
2
)
6
a
CH
2
OH
7:1
4
5
2.5
1
85[25]
90[36]
>19:1
(CH
3
)
2
3
CHOH
a
9:1
6
7
2
2
82[24]
88[36]
>19:1
15:1
8
9
1.5
86[36]
7:1
2
5.5
4
89[24]
75[36]
87[2]
>19:1
7:1
1
1
0
1
>19:1
1
2
PhCH
2
a
OH
10
min
99[36]
8:1
7
(
Continued on next page)

16 J. Zhou et al.
3
Table 2: Ferrier reaction of 3, 4, 6-tri-O-acetyl-D-glycal with acceptors in the
presence of the FeCl
3
•6H
2
O/C reagent system (Continued)
α/β
Time
(h)
Yield
a
ratiosb
Entry
Acceptors
Products
(%)
1
3
40
min
92[2]
>19:1
1
1
4
5
5.5
2.5
88[36]
82[41]
10:1
>19:1
1
1
1
6
7
8
4.5
1.5
0.5
85[36]
94[36]
85[42]
8:1
HOCH
2
CH
2
Cl 10a
7.5:1
>19:1
1
2
9
0
Cl
3
CCH
2
OH 11a
1
76[36]
80
9:1
1.5
>19:1
2
2
1
2
F
3
CCH
2
OH 12a
1
1
69
61
7:1
>19:1
2
2
3
4
2.5
87[36]
18:1
1.5
68
>19:1
(
Continued on next page)

FeCl
3
·6H
2
O/C
3
17
Table 2: Ferrier reaction of 3, 4, 6-tri-O-acetyl-D-glycal with acceptors in the
presence of the FeCl
3
•6H
2
O/C reagent system (Continued)
α/β
Time Yield
a
ratiosb
Entry
Acceptors
Products
(h)
(%)
2
2
5
6
1
84[40] >19:1
1.5
67
>19:1
2
2
7
8
1
74
57
>19:1
>19:1
1.5
2
3
9
0
0.5
3.5
56c[21]
7:1
7:1
82[43]
3
1
3
66[43] >19:1
3
3
2
3
0.5
0.5
91[44]
9:1
75[44] >19:1
(
Continued on next page)

18 J. Zhou et al.
3
Table 2: Ferrier reaction of 3, 4, 6-tri-O-acetyl-D-glycal with acceptors in the
presence of the FeCl
3
2
•6H O/C reagent system (Continued)
α/β
Time
(h)
Yield
a
ratiosb
Entry
Acceptors
Products
(%)
3
4
40 min 88[44]
7:1
3
5
0.5
86[24]
>19:1
a
Isolated yields.
α/β ratios were determined by H NMR.
The dosage of FeCl 6H O/C is 0.001 eq.
b
c
1
3
·
2
tri-O-acetyl-D-glucal with primary, secondary, benzyl, allyl, propargyl, and
halogenated alcohols; thioalcohol; and thiophenol proceeded smoothly under
the specified conditions. The reaction afforded 2,3-unsaturated glucosides in
good to excellent yields (69%–99%) with good anomeric selectivity (α/β > 7:1).
Comparing the results among entry 17, entry 19, and entry 21, it is clear that
the reaction rate became slower and the yield was decreased with the reduc-
tion in the nucleophilicity of acceptors. Additionally, complex alcohols such as
cholesterol also produced a high yield of product (87%, entry 23). Moreover,
we could obtain disaccharide smoothly while using sugar-derived alcohols as
the acceptor (entries 27 and 30). When the dosage of FeCl3·6H2O/C reduced to
0
2
.001 equiv, we successfully obtained the phenol glycoside in 56% yield (entry
9), which is hardly synthesized with other catalyst systems.[
32,33]
However, the reaction between tri-O-acetyl-D-galactal and benzyl alcohol
needed harsher conditions. We found that 0.5 equiv FeCl3·6H2O/C was re-
quired to promote the glycosylation with 92% yield and only α anomeric se-
lectivity. Likewise, a number of 2,3-unsaturated galactosides were obtained
successfully from primary, secondary, benzyl, allyl, propargyl, and halogenated
alcohols; thioalcohol; thiophenol; cholesterol; and sugar-derived alcohols, with
sole α anomeric selectivity, which probably resulted from the steric and
anomeric effects.
The structure and stereochemistry of all glycosidation products were
determined through spectroscopic analysis and also by comparison with the
[
39–44]
reported data.
In vitro antitumor activity of some of the compounds
was evaluated against the human k562 cancer cell line by the standard MTT
assay.[ They were proven to possess moderate antitumor activity as shown
in Table 3.
45]
More significantly, this synthetic methodology was shown to be reliable on
a 2 g scale of tri-O-acetyl-D-glucal in the presence of benzyl alcohol to give

FeCl
3
2
·6H O/C
3
19
Table 3: Inhibition of resistant K562 cell proliferation by some glycosidation products
Compound
Sample concentration (μg/mL)
Inhibition rate (%)
DDP
10
60.1
23.2
11.5
24.0
23.1
9
1
2
3
b
100
100
100
100
3b
2b
1b
DDP: cis-dichlorodiamminoplatinum-II.
an excellent yield (95%), and the catalyst could be easily recovered by sim-
◦
ple filtration and drying at 120 C for 3 h. Furthermore, over three cycles, the
catalyst did not show any significant loss in activity. [
32,39]
In summary, we have developed a mild and environmentally friendly
iron (III)–catalyzed glycosylation method for synthesizing 2,3-unsaturated glu-
cosides and 2,3-unsaturated galactosides in high anomeric selectivity. This
method was applied to a wide range of acceptors, including primary, sec-
ondary, benzyl, allyl, propargyl, and halogenated alcohols; thioalcohol; thio-
phenol; cholesterol; and sugar derivatives. Furthermore, the efficient applica-
bility of this methodology to gram scales of synthesis and the recyclability of
the catalyst make this approach highly practical.
EXPERIMENTAL
General Experimental Methods
1H NMR spectra and 13C NMR spectra were recorded on a Bruker DRX-
500 MHz spectrometer using tetramethylsilane as internal standard and
CDCl3 as solvent. Mass spectra were determined on LTQ-XL (Thermo Scien-
tific, USA) with an (ESI) ion trap mass spectrometer. Silica gel (10–40 μm,
Yantai, China) was used for column chromatography. TLC plates (10–40 μm,
Yantai, China) were applied to monitor the reactions. All the reagents were
purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China) and
were used as received without further purification. The supported ferric cata-
lysts were prepared according to the reported methods.[
37,38]
Preparation of FeCl ·6H O/C Catalyst
3
2
[
38]
The preparation of FeCl3·6H2O/C followed the literature method.
In
brief, 1 g of iron (III) chloride hexahydrate, 1 g of activated carbon, and 4.0 mL
of absolute ethanol were added to a round-bottom flask. Then, the mixture was

20 J. Zhou et al.
3
refluxed for 30 min. Finally, the solvent was evaporated under reduced pres-
◦
[46]
sure and the resulting catalyst was baked in an oven at 120 C for 2 h.
General Experimental Procedure for the Synthesis
of 2,3-Unsaturated Glucosides
To a stirred solution of tri-O-acetyl-D-glucal (100 mg, 0.37 mmol) in DCM
(1 mL) were added the corresponding alcohol (0.41 mmol, 1.1 equiv) and
FeCl3·6H2O/C (5 mol%) at ambient temperature. After the reaction was com-
pleted (monitored by TLC), the reaction mixture was filtered and the catalyst
was washed with dichloromethane. After evaporation of the solvent under vac-
uum, the crude products were purified by silica gel column chromatography
(petroleum ether/EtOAc = 10/1).
General Experimental Procedure for the Synthesis of
,3-Unsaturated Galactosides
2
To a stirred solution of tri-O-acetyl-D-galactal (50 mg, 0.185 mmol) in DCM
(1 mL) were added the corresponding alcohol (0.204 mmol, 1.1 equiv) and
FeCl3·6H2O/C (50 mol%) at ambient temperature. After the reaction was com-
pleted (monitored by TLC), the reaction mixture was filtered and the catalyst
was washed with dichloromethane. After evaporation of the solvent under vac-
uum, the crude products were purified by silica gel column chromatography
(petroleum ether/EtOAc = 10/1).
Spectral Data for New Compounds
Trifluoroethyl 4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-enopyranoside
(12b)
1
Viscous oil; α/β = 7:1; H NMR (500 MHz, CDCl3): δ (ppm) 2.06–2.09 (m,
H), 3.95–4.09 (m, 3 H), 4.18–4.20 (m, 1H), 5.09 (s, 1 H), 5.31 (dd, 1 H, J =
.4, 9.8 Hz), 5.82–5.94 (m, 2 H). 13C NMR (125 MHz, CDCl3): δ (ppm) 20.60,
6
1
2
0.82, 62.51, 64.78, 64.85, 65.06, 67.39, 94.47, 126.19, 130.34, 170.15, 170.63.
+
MS (ESI): m/z calculated for [M+Na] C12H15F3O6Na 335.07, found 335.17.
+
ESI-HRMS: Calcd for C12H15F3O6Na (M+Na ) 335.0713, found 335.0731.
2
,4,6-tri-O-acetyl mequinol galactosyl-4,6-di-O-acetyl-2,
-dideoxy-α-D-erythro-hex-2-enopyranoside (15b)
3
Viscous oil; [α]D20 = +108 (c 0.23, CH2Cl2); α only; H NMR (500 MHz,
1
CDCl3): δ (ppm) 2.05–2.18 (m, 15H), 3.78 (s, 3H), 3.92–3.95 (m, 2H), 4.10–4.21
(m, 3 H), 4.24–4.28 (m, 2H), 4.83–4.85 (d, 1H), 5.24 (s, 1H), 5.32–5.39 (m, 1H),
5.44–5.45 (d, 1 H, J = 2.9 Hz), 5.63–5.66 (m, 1H), 5.85–5.87 (m, 1H), 6.81–6.83

FeCl
3
2
·6H O/C
3
21
(
dd, J = 2.2, 6.9 Hz), 6.94–6.96 (dd, J = 2.2, 6.9 Hz, 2H). 13C NMR (125 MHz,
CDCl3): δ (ppm) 14.09, 20.65, 20.78, 20.80, 20.92, 22.67, 29.34, 29.68, 31.91,
55.65, 61.55, 62.51, 64.96, 65.30, 67.29, 69.67, 70.81, 73.30, 91.05, 101.09,
1
14.55, 118.58, 127.04, 129.34, 151.11, 155.71, 169.16, 170.14, 170.37, 170.65.
+
MS (ESI): m/z calculated for [M+Na] C29H36O15Na 647.20, found 647.33. ESI-
+
HRMS: Calcd for C29H36O15Na (M+Na ) 647.1946, found 647.1990.
Trichloroethyl 4,6-di-O-acetyl-2,3-dideoxy-α-D-derythro-hex-2-enopyranoside
(
28b)
Yellow oil; [α]D20 = –130 (c 0.16, CH2Cl2); α only; H NMR (500 MHz,
1
CDCl3): δ (ppm) 6.20 (1H, dd, J = 10.0, 5.5 Hz), 6.12 (1H, dd, J =
1
4
0.0, 3.0 Hz), 5.30 (1H, d, J = 2.5 Hz), 5.05 (1H, dd, J = 5.0, 2.0 Hz),
.45–4.42 (1H, m), 4.33–4.31 (1H, m), 4.23–4.17 (3H, m), 2.07 (3H, s), 2.06
(
9
3H, s); 13C NMR (125 MHz, CDCl3) δ (ppm): 170.5, 170.2, 129.2, 126.2, 96.4,
4.1, 79.3, 67.5, 62.6, 62.5, 20.7 (2C). MS (ESI): m/z calculated for [M+Na]
+
C12H15Cl3O6Na 382.98, found 383.08. ESI-HRMS: Calcd for C12H15Cl3O6Na
(
+
M+Na ) 382.9826, found 382.9858.
Trifluoroethyl 4,6-di-O-acetyl-2,3-dideoxy-α-D-derythro-hex-2-enopyranoside
29b)
(
Viscous liquid; [α]D20 = –104 (c 0.14, CH2Cl2); α only; H NMR (500 MHz,
1
CDCl3) δ (ppm): 6.21 (1H, dd, J = 10.0, 5.5 Hz), 6.07 (1H, dd, J = 10.0,
3
.0 Hz), 5.16 (1H, d, J = 2.5 Hz), 5.05 (1H, dd, J = 5.5, 2.0 Hz), 4.34–4.33
(
1H, m), 4.28–4.21 (2H, m), 4.20–3.96 (2H, m), 2.09 (3H, s), 2.08 (3H, s);
1
3
C NMR (125MHz, CDCl3) δ (ppm): 170.5, 170.2, 129.1, 126.2, 94.0, 67.4,
+
6
4.6, 64.4, 62.6, 62.4, 20.7, 20.6. MS (ESI): m/z calculated for [M+Na]
C12H15F3O6Na 335.07, found 335.17. ESI-HRMS: Calcd for C12H15F3O6Na
+
(
M+Na ) 335.0713, found 335.0727.
Cholesteryl 4,6-di-O-acetyl-2,3-dideoxy-α-D-threo-hex-enopyranoside (30b)
White solid; [α]D20 = –45 (c 0.08, CH2Cl2); α only; H NMR (500 MHz,
1
CDCl3) δ (ppm): 6.09 (1H, dd, J = 10.0, 5.4 Hz), 6.01 (1H, dd, J = 10.0, 3.0 Hz),
5.34 (1H, d, J = 4.9 Hz), 5.20 (1H, d, J = 2.6 Hz), 5.00 (1H, dd, J = 5.2, 2.5 Hz),
4.40–4.39 (1H, m), 4.22–4.20 (2H, m), 3.54–3.59 (1H, m), 2.43–2.39 (1H, m),
2
.34–2.29 (1H, m), 2.06 (3H, s), 2.05 (3H, s), 2.01–0.66 (41H, m); 13C NMR
(125 MHz, CDCl3) δ (ppm): 170.6, 170.3, 130.7, 124.7, 95.6, 80.7, 66.6, 63.2,
6
3.0, 48.9, 43.2, 34.3, 31.7, 25.6, 23.1, 22.4, 21.1, 20.8 (2C), 16.1. MS (ESI): m/z
+
calculated for [M+Na] C37H58O6Na 621.43, found 621.50. ESI-HRMS: Calcd
+
for C37H58O6Na (M+Na ) 621.4126, found 621.4141.

22 J. Zhou et al.
3
Methyl 4,6-di-O-acetyl-2,3-dideoxy-α-D-threo-hex-2-enopyranoside (31b)
White solid; [α]D20 = –159 (c 0.16, CH2Cl2); α only; H NMR (500 MHz,
1
CDCl3) δ (ppm): 6.09 (1H, dd, J = 10.1, 5.2 Hz), 6.04 (1H, dd, J = 10.1,
2
.9 Hz), 5.13 (1H, d, J = 2.6 Hz), 5.00 (1H, dd, J = 5.2, 2.5 Hz), 4.41–4.38
(
(
1H, m), 4.22–4.19 (2H, m), 3.45–3.40 (1H, m), 2.19 (1H, m), 2.07 (3H, s), 2.06
3H, s), 1.65–0.65 (17H, m); 1 C NMR (125 MHz, CDCl3) δ (ppm): 170.6, 170.3,
3
1
2
3
30.7, 124.7, 95.6, 80.7, 66.6, 63.2, 63.0, 48.9, 43.2, 34.3, 31.7, 25.6, 23.1,
+
2.4, 21.1, 20.8(2C), 16.1. MS (ESI): m/z calculated for [M+Na] C20H32O6Na
+
91.21, found 391.33. ESI-HRMS: Calcd for C20H32O6Na (M+Na ) 391.2091,
found 391.2100.
2
,4,6-tri-O-acetyl mequinol galactosyl-4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-
hex-2-enopyranoside (33b)
Viscous liquid; [α]D20 = –47 (c 0.33, CH2Cl2); α only; H NMR (500 MHz,
1
CDCl3) δ (ppm): 6.95–6.94 (2H, d, J = 9.0 Hz), 6.95–6.94 (2H, d, J = 9.1 Hz),
6
.10–6.07 (1H, m), 5.86–5.83 (1H, dd, J = 10.1, 3.0 Hz), 5.47–5.46 (1H, d, J
3.1 Hz), 5.38–5.34 (1H, m), 5.03–5.01 (1H, dd, J = 5.7, 1.9 Hz), 4.85–4.83
1H, d), 4.28–4.22 (2H, m), 4.20–4.17 (2H, m), 4.14–4.11 (2H, m), 3.97–3.96
=
(
(
(
1
3
1H, m), 3.99–3.97 (1H, m), 3.78 (3H, s), 2.18–2.05 (15H, m). C NMR
125 MHz, CDCl3) δ (ppm): 170.65, 170.38, 170.30, 170.26, 169.26, 155.68,
151.10, 129.92, 125.28, 118.55, 114.53, 101.09, 90.44, 72.78, 70.82, 69.60,
6
7.16, 65.21, 62.26, 62.23, 61.61, 60.36, 55.62, 29.66, 20.75, 20.73, 20.63, 14.16.
+
MS (ESI): m/z calculated for [M+Na] C29H36O15Na 647.20, found 647.33. ESI-
+
HRMS: Calcd for C29H36O15Na (M+Na ) 647.1946, found 649.1974.
ACKNOWLEDGMENTS
We thank the analytic center of East China Normal University for data mea-
surement. We also gratefully thank Prof. Qiang Li for helpful discussion.
FUNDING
This project was supported by the Shanghai Natural Science Foundation
(11ZR1410400), Large Instruments Open Foundation of East China Normal
University (2013-86&2014-03), and National Students Innovative Experimen-
tal Projects (No. 1310269021)
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