Oligo-polyethene glycol (PEG)-modified 14-deoxy-11,12-didehydroandrographolide derivatives: Synthesis, solubility and anti-bacterial activity

Article abstract of DOI:10.1016/j.tet.2016.03.025

A class of 14-deoxy-11,12-didehydroandrographolide (DA) derivatives with oligo-polyethylene glycol (PEG) substituents has been synthesized. It is found that small degree of polymerization of PEG favors the synthesis of dual-PEGylated DA derivatives, whereas large degree of polymerization is good for the preparation of mono-PEGylated DA derivatives. As compared to the prototype compound DA, the PEGylated DA derivatives show enhanced water solubility which is beneficial to drug's bioavailability. Preliminary study finds that the PEGylated DA derivatives exhibit better anti-bacterial activity than that of DA.

Full text of DOI:10.1016/j.tet.2016.03.025

Accepted Manuscript
Oligo-polyethene glycol (PEG)-modified 14-deoxy-11,12-didehydroandrographolide
derivatives: synthesis, solubility and anti-bacterial activity
Zhen Wang, Yi Chen, Feipeng Wu
PII:
S0040-4020(16)30158-2
10.1016/j.tet.2016.03.025
TET 27565
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 20 November 2015
Revised Date: 3 March 2016
Accepted Date: 8 March 2016
Please cite this article as: Wang Z, Chen Y, Wu F, Oligo-polyethene glycol (PEG)-modified 14-
deoxy-11,12-didehydroandrographolide derivatives: synthesis, solubility and anti-bacterial activity,
Tetrahedron (2016), doi: 10.1016/j.tet.2016.03.025.
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ACCEPTED MANUSCRIPT
Graphical Abstract
O
O
HO
O
O
OMe
O
n
O

ACCEPTED MANUSCRIPT
Oligo-polyethene glycol (PEG)-modified
1
4-deoxy-11,12-didehydroandrographolide derivatives: synthesis,
solubility and anti-bacterial activity
a,b
a
a
Zhen Wang , Yi Chen *, Feipeng Wu
a
Key Laboratory of Photochemical Conversion and Optoelectronic Materials,
Technical Institute of Physics and Chemistry, The Chinese Academy of Sciences,
Beijing, 100190, China. Fax: 86 10 6487 9375; Tel: 86 10 8254 3595; E-mail:
yichen@mail.ipc.ac.cn
b
University of Chinese Academy of Sciences, Beijing, 100190, China.

ACCEPTED MANUSCRIPT
Oligo-polyethene glycol (PEG)-modified
1
4-deoxy-11,12-didehydroandrographolide derivatives: synthesis,
solubility and anti-bacterial activity
a,b
a
a
Zhen Wang , Yi Chen *, Feipeng Wu
a
Key Laboratory of Photochemical Conversion and Optoelectronic Materials,
Technical Institute of Physics and Chemistry, The Chinese Academy of Sciences,
Beijing, 100190, China. Fax: 86 10 6487 9375; Tel: 86 10 8254 3595; E-mail:
yichen@mail.ipc.ac.cn
b
Technical Institute of Physics and Chemistry, The Chinese Academy of Sciences,
Beijing, 100190, China.
c
University of Chinese Academy of Sciences, Beijing, 100190, China.
Abstract: A class of 14-deoxy-11,12-didehydroandrographolide (DA) derivatives
with oligo-polyethylene glycol (PEG) substituents has been synthesized. It is found
that small degree of polymerization of PEG favors the synthesis of dual-PEGylated
DA derivatives, whereas large degree of polymerization is good for the preparation of
mono-PEGylated DA derivatives. As compared to the prototype compound DA, the
PEGylated DA derivatives show enhanced water solubility which is beneficial to
drug’s bioavailability. Preliminary study finds that the PEGylated DA derivatives
exhibit better anti-bacterial activity than that of DA.
Keywords: synthesis, PEGylated 14-deoxy-11,12-didehydroandrographolides,
solubility, bioactivity.
1

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1
. Introduction
Water solubility of active pharmaceutical ingredients has always been a concern for
formulators, since inadequate aqueous solubility may hamper development of
1
parenteral products and limit bioavailability of oral products. Solubility plays an
essential role in drug disposition because the maximum rate of passive drug transport
across a biological membrane, the main pathway for drug absorption, is the product of
permeability and solubility. Although the oral bioavailability of a drug depends on
aqueous solubility, drug permeability, dissolution rate, first-pass metabolism and
susceptibility to efflux mechanisms, aqueous solubility and drug permeability are two
2
important parameters attributed to oral bioavailability.
Poor solubility has been identified as the cause of numerous drug development
failures. It has been estimated that anywhere from 40 to 70% of all new chemical
entities entering drug development programs possess insufficient aqueous solubility to
allow consistent gastrointestinal absorption of a magnitude sufficient to ensure
3
therapeutic efficacy. Recently, some reviews have contributed to techniques for the
4
5,6
improvement of drug’s solubility including salt formation, particle technology
7
8
9
cyclodextrins complexes, lipid-based formulations and prodrugs effect.
1
4-Deoxy-11,12-didehydroandrographolide (DA) (Scheme 1), one of the main
active constituents in Andrographis paniculata, exhibited various biological activities
including antiinflammation, antivirus, antitumor, antibacterium, hepatoprotection and
1
0-14
analgesia.
It is widely known as “natural antibiotics” due to being isolated from
the leaves of the Andrographis paniculata (Burm.f.) Wall. ex Nees (Acanthaceae)
2

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1
5,16
plant.
Despite DA exhibits high bioactivity and low toxicity, the poor aqueous
solubility of DA has been a concern as it results in low dissolution and limited
formulations and has hindered the clinical use.
15
O
16
14
O
13
12
20
11
17
1
4
9
2
3
8
7
1
0
6
HO
5
18
19
HO
DA
Scheme 1. Chemical structure of 14-deoxy-11,12-didehydroandrographolide (DA)
Recently, most studies of DA have been focused on structure-activity relationship.
A class of new DA derivatives has been synthesized and evaluated for anti-HBV
1
7
18
properties or hepatoprotective activity. Although the solubility of DA modified
with potassium/sodium succinate semi ester has been developed, several side effects
including allergy, digestive tract, blood system and heating have been observed in
1
9-22
clinic.
In this work, polyethylene glycol monomethyl ether with different degree
of polymerization used as hydrophilic group was introduced to improve the solubility
of DA. PEG have been extensively studied for their potential biomedical applications
2
3-25
26-28
as scaffolds in tissue engineering
and as drug delivery systems
due to their
2
9-31
biocompatibility, nontoxicity, and biodegradability.
Herein, we report the
synthesis of PEG-modified DA derivatives (Scheme 2) and their solubility. The aim is
to explore the effect of the degree of polymerization of PEG on the structure of DA
derivatives as well as their solubility and bioactivity, and to develop a simple
3

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approach to the preparation of water-soluble DA derivatives.
Scheme 2. Chemical structures of mPEGs-substituted DA derivatives 1-5.
2
. Results and discussion
2
.1. Design and synthesis of PEGylated DA derivatives 1-5
3
2
According to molecular hybridization principle, esterification of natural
compounds is an effective approach for achieving promising derivatives. A series of
3
3
34
active derivatives of caudatin and hemslecin A were obtained by esterification, and
which showed obviously enhanced activity compared with the parent compounds.
1
7
Although DA has many reaction sites, Ji-Jun Chen and coauthors have found in
their study of DA derivatives as novel anti-hepatitis B virus agents that (1) the double
bond between C and C , and the conjugated double bonds between C and C , or
8
17
11
14
C12 and C15 are necessary for DA to maintain anti-HBV activity and decreasing
cytotoxicity, and (2) C -O-substituted compounds with the free OH group at C can
1
9
3
4

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provide higher anti-HBV activity than other analogues. Based on those findings, we
attach PEG units to C -OH or both C -OH and C -OH by mono-esterification and
1
9
19
3
dual-esterification, respectively, to compare their bioactivity, and expect to offer
valuable information for seeking DA-based drug candidates.
PEGylated DA derivatives (1-5) was obtained starting from andrographolide,
which was dehydrated with activated alumina in refluxing anhydrous pyridine to give
dehydroandrographolide DA in 85% isolated yield. DA was treated with 1.1 equiv. or
2
.2 equiv. of PEG-succinate semi-ester, which was obtained by the reaction of mPEG
with succinic anhydride in dichloromethane (DCM), in the presence of
4
1
-dimethylaminopyridine
(DMAP)
and
-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC-HCl) in DCM
to afford 1-5 in good yields (60 - 78%) after column chromatography. The synthetic
route is outlined in Scheme 3.
PEG
O
O
O
b
O
O
O
HO
O
O
O
O
HO
PEG
O
a
O
HO
HO
R O
1
1
.1 equiv. or 2.2 equiv.
c
HO
Andrographolide
HO
DA
R O
2
1 - 5
Reagents and conditions: (a) Al O , pyridine, reflux, 85%; (b) Et N (cat.), DCM, rt,
2
3
3
7
5%; (c) DMAP (cat.), EDC-HCl, DCM, rt, 65-78%.
Scheme 3. Synthesis of PEGylated DA derivatives 1-5.
5

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The regioselectivity of mono- and dual-esterification at C - and C -postion was
3
19
investigated by treatment of DA with 1.1 equiv. and 2.2 equiv. of PEGs, respectively.
It was found that no significant selectivity was observed when the degree of
polymerization of PEG is small. As shown in Scheme 4, both mono- and
dual-substituted DA derivatives (in yield ratio of 1:1) were obtained when DA is
treated with 1.1 equiv. of 2-(2-methoxyethoxy)ethanol-succinate semi-ester. The
mono-substituted DA was converted completely to dual-substituted DA derivative 1
with the addition of another stoichiometric 2-(2-methoxyethoxy)ethanol-succinate
semi-ester.
Scheme 4. Synthesis of DA derivative 1.
Different results were obtained when the degree of polymerization of PEG is
increased. It was found that although the dual-substituted DA derivatives 2 and 3,
6

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which were obtained by treatment of DA with 2.2 equiv. of triethylene glycol
monomethyl ether succinate semi-ester and tetraethyleneglycol monomethyl ether
succinate semi-ester (Scheme 5), respectively, were detected in the reaction,
mono-substituted DA derivatives 4 (65%) and 5 (70%) as main products were
obtained when DA was treated with 1.1 equiv. of corresponding succinate semi-ester.
The selective esterification at C -position with a large PEG unit is probably because
19
PEG with a large degree of polymerization is easy to form micelles in solution, which
reduces probability of collision between PEG and OH at C -position due to more
3
steric hindrance. The results suggested that the selectivity of mono- and
dual-substituted DA derivatives can be modulated by changing the stoichiometry of
PEG-succinate semi-ester with a modulate degree of polymerization.
O
O
OMe
O
O
O
O
2
3
: 75 %
: 72 %
O
RO
RO
HO
O
O
O
O
HO
O
OMe
DA
4
5
: 65 %
: 70 %
HO
RO
O
O
OMe
3
2
3
, 4
R =
O
O
O
, 5
R =
OMe
4
O
Scheme 5. Synthesis of mono-and dual-substituted DA derivatives 2 - 5.
7

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2
.2. Solubility and partition coefficient of PEGylated DA derivatives 1-5.
Water solubility of PEGylated DA derivatives was measured by HPLC analyst.
The concentrations of 1 – 5 were measured in deionized water at ambient
temperature. As compared to parent DA, the solubility of PEGylated DA
derivatives 1 – 5 was increased. As shown in Table 1, the solubility of 3 (0.68
mg/mL) was increased by 22 times as compared to DA (0.03 mg/mL) in 25 ºC in
water. Further study found that the solubility of PEGylated DA derivative is
greatly influenced by the degree of polymerization of PEG. Comparing the
solubility of 1, 2 and 3 found that the solubility was increased with increase of the
degree of polymerization of PEG, the solubility of PEGylated DA was changed
from 0.06 mg/mL (1) to 0.29 mg/mL (2) to 0.68 mg/mL (3) when substituent
changed from 2-(2-methoxyethoxy)ethanol to triethylene glycol monomethyl ether
to tetraethylene glycol monomethyl ether. Such a large change indicated that the
water-soluble modification of DA with oligo-polyethene glycol is effective,
especially with large degree of polymerization of PEGs. Moreover, it was found
that no distinct increase was obtained when mono-PEGylated DA derivatives (4:
0
.22 mg/mL; 5: 0.60 mg/mL) were changed to corresponding dual-PEGylated DA
derivatives (2: 0.29 mg/mL; 3: 0.68 mg/mL), which suggested that the solubility of
DA derivatives is mainly influenced by the degree of polymerization of PEG. In
addition, similar results were obtained when water was replaced by buffer solution,
it was found that the solubility of PEGylated DA derivatives 1 – 5 in PBS buffer
solution is similar to that in water, and the solubility did not affected by pH value
8

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(
pH = 4.0, 7.4, 8.2), which is beneficial to drug’s bioavailability as oral product.
Table 1. The solubility (C) and partition coefficient (log P) of DA and DA
derivatives 1-5 in water (25 ºC)
Compound DA
C(mg/mL) 0.03 0.06 0.29 0.68 0.22 0.60
log P 3.6 3.4 2.4 2.7 2.5 2.2
1
2
3
4
5
Partition coefficient (log P) is one of important physicochemical parameters used to
describe the relationship of drugs with their biological, pharmacokinetical and
metabolic properties, and an optimal log P value is required for a drug to ensure its
3
5,36
efficient uptake.
Log P is usually measured in octanol–water system or
3
7,38
liposome-water system,
the latter is a more suitable descriptor for mimic
biomembranes than the corresponding octanol-water system. In this paper, log P of
derivatives 1 – 5 together with DA are measured in liposome-water system and the
data are listed in Table 1. As compared to DA, the log P values of 1 – 5 were
decreased, but all of them appeared in the range of 2.2 – 3.4 (Table 1), such large log
P values indicated that 1 – 5 have high-permeability.
2
.3. Anti-bacterial activity of PEGylated DA derivatives 1 – 5.
The biological evaluation of PEGylated DA derivatives is performed by
using DA derivatives against Gram-negative bacteria (E.coli.). Although DA
exhibited various biological activities such as antiinflammation, antivirus,
9

ACCEPTED MANUSCRIPT
antitumor, and antibacterium, we employed E. coli. (ATCC 25922) as tested
bacterial just because it is easy obtained. The DA derivatives 1 – 5 were
dissolved in PBS (pH = 7.4) buffer solution at the concentration of 1.0 mg/mL
and then screened for in vitro antibacterial activity against Gram-negative
bacteria (E. coli.). Table 2 shows the data of antibacterial activity of derivatives
1
– 5. It was found that all derivatives 1 – 5 exhibited better antibacterial
activity than that of their parent DA probably due to the increase of solubility in
buffer solution, among them the derivative showed the best antibacterial
5
activity with high inhibition rate (86%) and low Minimal inhibitory
concentration (3.5 mg/mL). It is worth noting that increasing the concentration
of DA derivatives can improve the anti-bacterial activity, as shown in Table 2,
more than 99% inhibition was obtained when the concentration of
5 was
increased to 10 mg/mL. Further investigation found that the mono-PEGylated
DA derivatives exhibited better antibacterial activity than that of
dual-PEGylated DA derivatives. As shown in Table 2, the inhibition rate of
mono-PEGylated derivatives
4
(74%) and
5 (86%) is larger than that of
dual-PEGylated derivative (54%) and
2
3
(62%) at the same concentration (1.0
mg/mL), which suggested that free OH in C -position may play a key role in
3
antibacterial activity although the mechanism is not clear.
1
0

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Table 2. The antibacterial activity of DA and DA derivatives 1 – 5.
a
Compound
DA
1
2
3
4
5
5
Inhibition rate
1
3
30
71
12
62
6.5
74
8.5
86
3.5
≥ 99
(%)
b
MIC(mg/mL)
10
a
b
concentration: 10 mg/mL; MIC: Minimal inhibitory concentration.
This study represents a platform for the development of a simple approach to
improving the solubility of 14-deoxy-11,12-didehydroandrographolide and their
evaluation of biological activity. Although the study presented herein is not very
satisfied such as solubility and anti-bacterial activity, it has been demonstrated that
the solubility of 14-deoxy-11,12-didehydroandrographolide can be significantly
enhanced with polyethene glycols modification, and great solubility can be
obtained with a large degree of polymerization of PEG. Solubility is one of key
physicochemical parameters, and plays an essential role in drug disposition, since
the maximum rate of passive drug transport across a biological membrane, the
main pathway for drug absorption, is the product of permeability and solubility.
Using PEGs as hydrophilic groups to modify the solubility of
1
4-deoxy-11,12-didehydroandrographolide has some advantages such as rich and
various in raw materials, facile preparation and nonionic group. What is more,
PEGs exhibit biocompatibility, low/non-toxicity, and biodegradability. From a
practical viewpoint, it is desirable for a drug’s candidate to have some merits, such
as good solubility, suitable partition coefficient, non or low toxicity and efficient
11

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biological activity. This can be achieved by further modifying the molecular
structure and will be the subject of future studies.
3
. Conclusions
In summary, a simple approach to improving the water solubility of
4-deoxy-11,12-didehydroandrographolide has been developed. It has demonstrated
1
that PEGylated 14-deoxy-11,12-didehydroandrographolide derivatives exhibit good
solubility, and the solubility is increased with increase of the degree of polymerization
of PEG. With a moderate degree of polymerization, both mono- and dual-PEGylated
1
4-deoxy-11,12-didehydroandrographolide derivatives can be selectively obtained.
4
. Experimental
4.1. General
1
13
H and C NMR spectra were recorded at 400 and 100 MHz, respectively, with
TMS as an internal reference. MS spectra were recorded with TOC-MS spectrometer.
The solvents used for solubility and partition coefficient were high-performance
liquid chromatography (HPLC) grade. All chemicals for synthesis were purchased
from commercial suppliers and were used without further purification. Reaction
monitored by TLC silica gel plates (60F-254). Column chromatography was
performed on silica gel (70-230 mesh).
4.2. Solubility and partition coefficient measured with HPLC analysis
The water solubility of DA and PEGylated DA derivatives 1 – 5 was determined
1
2

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by HPLC analysis (Shimpack VP-ODS) with a reversed-phase C18 column (250 ×
4
.6 mm, 5µm, serial no. 8072399) and injection volume of 20 µL. The mobile
phase was a mixture of water and methanol (25:75, v/v); the flow rate was 1.0
mL/min and the detection wavelength was 254 nm.
The solubility of the DA derivatives was determined in deionized water (pH 7.0)
by adding excess amounts of the mPEGs-substituted DA derivatives to snap-cap
Eppendorf tubes. The resulting mixture was sufficiently vortexed and then placed
in an incubator at 37ºC for 24 hrs. Aliquots were centrifuged at 10,000 rpm for 10
min. The supernatant layer was carefully collected and filtered, then diluted to
linear range with methanol. The DA derivatives concentration was then quantified
by HPLC from a standard calibration curve.
The methods for measurement of log P values of DA and PEGylated DA
3
9
derivatives 1 – 5 in liposome-water system see literature.
.3. Anti- bacterial assay
4
The in vitro antimicrobial activity of the synthesized compounds was
investigated against Gram-negative bacteria E. coli (ATCC 25922), in which
cultures were maintained on malt agar at 4ºC and sub-cultured every month. Spore
suspension was obtained by washing agar plates with PBS buffer solution (pH =
7
.4), then added to each well to a final volume of 100 µL. The inhibition growth
detected by the naked eye, assays was performed using the micro-dilution
4
0
method by preparing a serial of dilutions in 96-well microtiter plates. PEGylated
DA derivatives were diluted in PBS buffer solution (1.0 mg/mL), then added to
1
3

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microplates containing Broth Malt medium with inoculum and incubated for 24 h
at 37 ºC on a rotary shaker in ambient atmosphere. Triplicates were used in all
experiments and repeated each experiment three times. The determination of the
minimal inhibitory concentration (MIC) of DA derivatives was performed
4
1
according to literature method
.4. General procedure for the preparation of PEGylated DA derivatives 1-5.
The synthetic routes for 1 – 5 were presented in Scheme 3, and the detailed
4
1
8
procedures were as follows: To the solution of DA
(1.0 mmol) and
4
2
PEG-succinate semi-ester (1.1 mmol for mono-substituted derivatives or 2.2
mmol for dual-substituted derivatives) in DCM (50 mL) was added
4
1
-dimethylaminopyridine
(DMAP,
0.2
mmol)
and
-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC-HCl, 2.0
mmol). The reaction mixture was stirred at ambient temperature for 24 h, washed
with HCl (1.0 N, 20 mL) and saturated brine (50 mL). After evaporation of the
solvent, the crude product was purified by flash column chromatography to afford
1
– 5.
1R,2R,4aR,5R)-1-(9,12-dioxo-2,5,8,13-tetraoxatetradecan-14-yl)-1,4a-dimeth
yl-6-methylene-5-((E)-2-(2-oxo-2,5-dihydrofuran-3-yl)vinyl)decahydronaphthalen
2-yl (2-(2-methoxyethoxy)ethyl) succinate (1). To the solution of DA (332 mg,
(
-
1
4
.0
mmol)
in
DCM
(50
mL)
was
added
-(2-(2-methoxyethoxy)ethoxy)-4-oxobutanoic acid (484 mg, 2.2 mmol), DMAP
(
24 mg, 0.2 mmol), and EDC-HCl (382 mg, 2.0 mmol). The reaction mixture was
1
4

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stirred at ambient temperature for 24 h, washed with HCl (1.0 N, 20 mL) and
saturated brine (50 mL). After evaporation of the solvent, the crude product was
purified by flash column chromatography (PE/EtOAc/AcOH = 20:20:1, v/v) to
1
afford 1 (574 mg) in yield of 78%. H-NMR (400 MHz, CDCl ): δ = 7.10 (s, 1H),
3
6
.88-6.82 (m, 1H), 6.08 (d, J = 15.6 Hz, 1H), 4.74 (s, 2H), 4.73 (s, 1H), 4.48-4.45
(
m, 1H), 4.20-4.17 (m, 3H), 4.10-3.66 (m, 4H), 3.65-3.62 (m, 4H), 3.58-3.56 (m,
4
2
H), 3.49-3.47 (m, 4H), 3.32 (s, 6H), 2.64-2.54 (m, 8H), 2.27 (d, J = 10.4 Hz, 1H),
1
3
.01-1.97 (m, 1H), 1.79-1.77 (m, 8H), 0.95 (s, 3H), 0.81 (s, 3H). C-NMR (100
MHz, CDCl ): δ = 172.2 (t), 171.7, 147.9, 143.1, 135.5, 129.2, 121.2, 109.3, 80.2,
3
7
2
7
1.8, 70.4, 69.4, 69.1, 65.1, 63.8 (d), 61.7, 58.9, 54.8, 41.6, 38.6, 38.2, 36.6, 29.3,
9.1 (m), 28.9, 24.1 (d), 22.5, 15.2. HRMS Calcd for C H O : 736.3670; Found:
3
8
56 14
36.3648.
(1R,2R,4aR,5R)-1,4a-dimethyl-6-methylene-2-((12-oxo-2,5,8,11-tetraoxapenta
decan-15-oyl)-5-((E)-2-(2-oxo-2,5-dihydrofuran-3-yl)vinyl)decahydronaphthalen-
-yl)methyl (2-(2-(2-methoxyethoxy)ethoxy)ethyl succinate (2). To the solution of
DA (332 mg, 1.0 mmol) in DCM (50 mL) was added
2-oxo-2,5,8,11-tetraoxapentadecan-15-oic acid (580 mg, 2.2 mmol), DMAP (24
(
1
1
mg, 0.2 mmol), and EDC-HCl (382 mg, 2.0 mmol). The reaction mixture was
stirred at ambient temperature for 24 h, washed with HCl (1.0 N, 20 mL) and
saturated brine (50 mL). After evaporation of the solvent, the crude product was
purified by flash column chromatography (PE/EtOAc/AcOH = 20:20:1, v/v) to
1
afford 2 (618 mg) in yield of 75%. H-NMR (400 MHz, CDCl ): δ = 7.10 (s, 1H),
3
1
5

ACCEPTED MANUSCRIPT
6
.88-6.82 (m, 1H), 6.07 (d, J = 15.6 Hz, 1H), 4.74 (s, 2H), 4.73 (s, 1H), 4.47-4.45
(
m, 1H), 4.27-4.15 (m, 3H), 4.11-3.66 (m, 4H), 3.64-3.60 (m, 8H), 3.59-3.54 (m,
8
2
H), 3.49-3.45 (m, 4H), 3.31 (s, 6H), 2.60-2.54 (m, 8H), 2.27 (d, J = 10.4 Hz, 1H),
1
3
.01-1.93 (m, 1H), 1.79-1.73 (m, 8H), 0.95 (s, 3H), 0.81 (s, 3H). C-NMR (100
MHz, CDCl ): δ = 174.6, 172.5, 147.8, 143.2, 133.8, 131.0, 129.3, 128.9, 121.3,
3
1
4
09.3, 78.9, 72.0 (m), 70.7 (m), 69.7, 69.1 (d), 64.0 (d), 63.1, 61.7, 58.7 (d), 54.8,
2.6, 38.6, 36.7, 32.8, 31.9, 29.5 (m), 29.0, 27.9 (d), 25.8, 22.7, 19.2, 14.1. HRMS
+
Calcd for C H O : 847.4079 [M + Na] , Found: 847.4092.
4
2
64 16
(
(1R,2R,4aR,5R)-1,4a-dimethyl-6-methylene-2-((15-oxo-2,5,8,11,14-pentaoxao
ctadecan-18-oyl)oxy)-5-((E)-2-(2-oxo-2,5-dihydrofuran-3-yl)vinyl)decahydronaph
thalen-1-yl)methyl (2,5,8,11-tetraoxatridecan-13-yl) succinate (3). To the solution
of DA (332 mg, 1.0 mmol) in DCM (50 mL) was added
1
5-oxo-2,5,8,11,14-pentaoxaoctadecan-18-oic acid (678 mg, 2.2 mmol), DMAP
(
24 mg, 0.2 mmol), and EDC-HCl (382 mg, 2.0 mmol). The reaction mixture was
stirred at ambient temperature for 24 h, washed with HCl (1.0 N, 20 mL) and
saturated brine (50 mL). After evaporation of the solvent, the crude product was
purified by flash column chromatography (PE/EtOAc/AcOH = 20:20:1, v/v) to
1
afford 3 (657 mg) in yield of 72%. H-NMR (400 MHz, CDCl ): δ = 7.12 (s, 1H),
3
6
.89-6.83 (m, 1H), 6.08 (d, J = 15.6 Hz, 1H), 4.74 (s, 2H), 4.73 (s, 1H), 4.47-4.45
(
m, 1H), 4.29-4.21 (m, 3H), 4.18-4.15 (m, 8H), 3.64-3.56 (m, 18H), 3.49-3.46 (m,
6
1
H), 3.31 (s, 6H), 2.60-2.54 (m, 8H), 2.27 (d, J = 10.4 Hz, 1H), 2.01-1.93 (m, 1H),
1
3
.79-1.46 (m, 10H), 0.95 (s, 3H), 0.81 (s, 3H). C-NMR (100 MHz, CDCl ): δ =
3
1
6

ACCEPTED MANUSCRIPT
1
6
2
72.2, 171.7, 147.9, 143.1, 135.5, 129.2, 121.2, 109.3, 80.2, 71.8, 70.4, 69.4, 69.1,
5.1, 63.8, 61.7, 58.9, 54.8, 41.6, 38.6, 38.2, 36.6, 29.3, 29.1, 29.0 (m), 28.9 (m),
4.1, 23.9, 22.5, 15.2. HRMS Calcd for C H O : 912.4719, Found: 912.4670.
4
6
72 18
(
(1R,2R,4aR,5R)-2-hydroxy-1,4a-dimethyl-6-methylene-5-((E)-2-(2-oxo-2,5-di
hydrofuran-3-yl)vinyl)decahydronaphthalen-1-yl)methyl
2-(2-(2-methoxyethoxy)ethoxy)ethyl succinate (4). To the solution of DA (332
mg, 1.0 mmol) in DCM (50 mL) was added
2-oxo-2,5,8,11-tetraoxapentadecan-15-oic acid (295 mg, 1.1 mmol), DMAP (24
(
1
mg, 0.2 mmol), and EDC-HCl (382 mg, 2.0 mmol). The reaction mixture was
stirred at ambient temperature for 24 h, washed with HCl (1.0 N, 20 mL) and
saturated brine (50 mL). After evaporation of the solvent, the crude product was
purified by flash column chromatography (PE/EtOAc/AcOH = 20:20:1, v/v) to
1
afford 4 (376 mg) in yield of 65%. H-NMR (400 MHz, CDCl ): δ = 7.11 (s, 1H),
3
6
1
3
1
.84-6.78 (m, 1H), 6.07 (d, J = 15.6 Hz, 1H), 4.75 (s, 2H), 4.72 (s, 1H), 4.47 (s,
H), 4.20-4.19 (m, 3H), 4.08-4.01 (m, 2H), 3.62-3.59 (m, 8H), 3.50-3.47 (m, 2H),
.31 (s, 3H), 2.59-2.54 (m, 4H), 2.27 (d, J = 10.4 Hz, 1H), 2.01-1.96 (m, 1H),
.78-1.41 (m, 4H), 1.27-1.18 (m, 5H), 1.06 (s, 2H), 0.95 (s, 1H), 0.81 (s, 3H).
1
3
C-NMR (100 MHz, CDCl ): δ = 174.6, 172.3 (m), 172.1, 147.9, 142.9, 137.6,
3
1
32.4, 130.9, 128.8, 121.2, 109.2, 78.8, 71.9 (m), 70.5 (m), 69.0, 63.8 (m), 58.9
(
d), 42.6, 38.4 (m), 36.6, 32.7, 31.7, 30.8, 29.4 (m), 27.7, 26.7, 22.4 (m), 19.1,
+
1
4.0. HRMS Calcd for C H O : 601.2989 [M + Na] , Found: 601.2950.
3
1
46 10
(
(1R,2R,4aR,5R)-2-hydroxy-1,4a-dimethyl-6-methylene-5-((E)-2-(2-oxo-2,5-di
1
7

ACCEPTED MANUSCRIPT
hydrofuran-3-yl)vinyl)decahydronaphthalen-1-yl)methyl
(
2,5,8,11-tetraoxatridecan-13-yl) succinate (5). To the solution of DA (332 mg, 1.0
mmol) in DCM (50 mL) was added 15-oxo-2,5,8,11,14-pentaoxaoctadecan-18-oic
acid (339 mg, 1.1 mmol), DMAP (24 mg, 0.2 mmol), and EDC-HCl (382 mg, 2.0
mmol). The reaction mixture was stirred at ambient temperature for 24 h, washed
with HCl (1.0 N, 20 mL) and saturated brine (50 mL). After evaporation of the
solvent, the crude product was purified by flash column chromatography
1
(
(
PE/EtOAc/AcOH = 20:20:1, v/v) to afford 5 (436 mg) in yield of 70%. H-NMR
400 MHz, CDCl ): δ = 7.11 (s, 1H), 6.84-6.76 (m, 1H), 6.07 (d, J = 15.6 Hz, 1H),
3
4
2
.75 (s, 2H), 4.72 (s, 1H), 4.47-4.45 (m, 1H), 4.20-4.16 (m, 3H), 4.10-3.65 (m,
H), 3.64-3.56 (m, 12H), 3.50-3.47 (m, 2H), 3.32 (s, 3H), 2.61-2.54 (m, 4H), 2.27
(
d, J = 10.4 Hz, 1H), 2.01-1.97 (m, 1H), 1.78-1.77 (m, 8H), 1.08 (s, 1H), 0.91 (s,
1
3
3
1
3
H), 0.81 (s, 3H). C-NMR (100 MHz, CDCl ): δ = 171.7, 171.4, 147.2, 142.8,
3
35.1, 130.3, 120.5, 108.5, 78.2, 71.2, 69.6, 68.3, 63.0, 62.3, 58.2 (d), 54.0, 41.8,
7.9, 35.8, 31.9, 31.1, 28.5, 26.8, 24.9, 22.8, 21.9, 18.3, 14.6. HRMS Calcd for
C H O : 622.3353, Found: 622.3323.
3
3
50 11
Acknowledgments
This work was supported by the National Natural Science Foundation of China
(
No 21302197 and No 21572241).
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