Semi-synthesis of C28-modified triterpene acid derivatives from maslinic acid or corosolic acid as potential α-glucosidase inhibitors

Article abstract of DOI:10.1016/j.bioorg.2020.103694

Combining two bioactive moieties by covalent bond into a novel single hybrid biological entity in view of the principle of active splicing, twenty-two C28-modified derivatives of pentacyclic dihydroxytriterpene carboxylic acids with saturated nitrogen heterocycle segments (i.e. 1-deoxynojirimycin or piperazines) have been synthesized. The inhibitory activities of all final target compounds on α-glucosidase were evaluated in vitro. The results of α-glucosidase inhibition assay indicate that some derivatives (e.g. 4b: IC₅₀ = 1468.4 μM; 12b: IC₅₀ = 499.6 μM 12c: IC₅₀ = 768.5 μM, 13c: IC₅₀ = 819.2 μM) show superior inhibitory activity in α-glucosidase than that of the precursor maslinic acid (IC₅₀ = 2540.6 μM) or corosolic acid (IC₅₀ = 1363.7 μM), in which compound 12b (IC₅₀ = 499.6 μM) possesses stronger inhibitory activity than that of acarbose (IC₅₀ = 606 μM). In addition, the result of enzyme kinetics study reveals that the inhibitory mechanism of the compound 12b is non-competitive inhibition and the inhibition constant K_i is 570 μM. The binding interaction between compounds with α-glucosidase are predicted by molecular docking simulation.

Full text of DOI:10.1016/j.bioorg.2020.103694

Journal Pre-proofs
Semi-synthesis of C28-modified triterpene acid derivatives from maslinic acid
or corosolic acid as potential α-glucosidase inhibitors
Xiaoqin Liu, Xufeng Zang, Xiaoli Yin, Wuying Yang, Jinxiang Huang,
Jianping Huang, Chunxian Yu, Chunshan Ke, Yanping Hong
PII:
S0045-2068(19)32178-9
DOI:
https://doi.org/10.1016/j.bioorg.2020.103694
YBIOO 103694
Reference:
To appear in:
Bioorganic Chemistry
Received Date:
Revised Date:
Accepted Date:
27 December 2019
21 February 2020
22 February 2020
Please cite this article as: X. Liu, X. Zang, X. Yin, W. Yang, J. Huang, J. Huang, C. Yu, C. Ke, Y. Hong, Semi-
synthesis of C28-modified triterpene acid derivatives from maslinic acid or corosolic acid as potential α-
glucosidase inhibitors, Bioorganic Chemistry (2020), doi: https://doi.org/10.1016/j.bioorg.2020.103694
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Semi-synthesis of C28-modified triterpene acid derivatives from maslinic acid or
corosolic acid as potential α-glucosidase inhibitors
Xiaoqin Liu a, Xufeng Zang b, Xiaoli Yin c, Wuying Yang a, Jinxiang Huang a, Jianping Huang d,*,
Chunxian Yu a, Chunshan Ke a, Yanping Hong a,*
a Jiangxi Key Laboratory of Natural Product and Functional Food, College of Food Science and
Engineering Jiangxi Agricultural University, Nanchang 330045, China
b Department of Applied Physics, Huzhou University, Huzhou 313000, China
c Library of Jiangxi Agricultural University, Nanchang 330045, China
d College of Science, Jiangxi Agricultural University, Nanchang 330045, China
*Corresponding Author: Tel.: +86-791-83813574. E-mail: huangchenchuan@126.com (J. Huang);
Tel.: +86-791-83813863. E-mail: xyqcjx@163.com (Y. Hong).
Abstract
Combining two bioactive moieties by covalent bond into a novel single hybrid biological entity
in view of the principle of active splicing, twenty-two C28-modified derivatives of pentacyclic
dihydroxytriterpene carboxylic acids with saturated nitrogen heterocycle segments (i.e. 1-
deoxynojirimycin or piperazines) have been synthesized. The inhibitory activities of all final target
compounds on α-glucosidase were evaluated in vitro. The results of α-glucosidase inhibition assay
indicate that some derivatives (e.g. 4b: IC50 = 1468.4 µM; 12b: IC50 = 499.6 µM 12c: IC50 = 768.5
µM, 13c: IC50 = 819.2 µM) show superior inhibitory activity in α-glucosidase than that of the
precursor maslinic acid (IC50 = 2540.6 µM) or corosolic acid (IC50 = 1363.7 µM), in which
compound 12b (IC50 = 499.6 µM) possesses stronger inhibitory activity than that of acarbose (IC50
= 606 µM). In addition, the result of enzyme kinetics study reveals that the inhibitory mechanism

of the compound 12b is non-competitive inhibition and the inhibition constant Ki is 570 µM. The
binding interaction between compounds with α-glucosidase are predicted by molecular docking
simulation.
Key words: Maslinic acid; Corosolic acid; 1-Deoxynojirimycin; Piperazine; α-Glucosidase
inhibitory activity.
1. Introduction
As one of the major problems threaten the health of human being, diabetes mellitus is a
metabolic disease characterized by elevated blood sugar which causing by insulin secretion defect
and impaired biological function, or both [1]. Diabetes can be roughly divided into type 1 and type
2, and almost over 90% of patients suffer from type 2 diabetes in clinical treatment [2]. Many serious
complications that usually aroused from type 2 diabetes, such as blurred vision [3], renal failure [4],
nerve damage [5] and cardiovascular disorders [6]. Currently, the effective strategies to cure type 2
diabetes are including oral hypoglycemic agents and insulin therapy, or a combination of both.
Meantime, a healthy diet and proper exercise as supplementary therapy are necessary [7, 8]. As one
of hypoglycemic drugs, inhibitors of α-glucosidase play a crucial role of decreasing the postprandial
blood glucose. The disaccharides and oligosaccharides from the diet cannot be converted to
monosaccharides due to the α-glucosidase activity is suppressed effectually [9]. Thus, it is essential
to regard α-glucosidase as an important target protein to treat type 2 diabetes and it also encourages
many scientists to develop new α-glucosidase inhibitors constantly. In recent years, researches of
α-glucosidase inhibitors primarily focused on plant extracts and synthetic organic compounds. The
natural compounds including 1-deoxynojirimycin (1-DNJ) [10], polysaccharides [11] and
polyphenols [12] extracted from plants all showed different degrees of inhibitory activity on α-
glucosidase. In the other hand, α-glucosidase inhibitors can be obtained from chemical synthesis,

such as benzotriazole derivatives [13], heterocyclic candidates [14], piperidine derivatives [15],
oxazolxanthone derivatives [16] and indolcarbohydrazones [17] have been studied and found
continuously. All the aforementioned α-glucosidase inhibitors are expected to be the potential
therapeutics to regulate blood glucose levels in the body. Meanwhile, conventional α-glucosidase
inhibitors (e.g. acarbose, voglibose and miglitol) usually lead some side effects on human body
during treatment, such as diarrhea, bellyache, flatulence and so on [18, 19]. Therefore, it is necessary
to develop α-glucosidase inhibitors with high activity and low toxicity as potential drugs for the
treatment of type 2 diabetes in clinical.
R2
R1
12
OH
28
3
2
HO
HO
O
MA ( R1 = H, R2 = CH3
)
CA ( R1 = CH3, R2 = H )
Fig. 1. The structure of maslinic acid and corosolic acid.
Natural products have been the most important sources for developing new drugs because of
their wide range of resources and high safety. Maslinic acid (MA) and corosolic acid (CA) are a
class of naturally pentacyclic dihydroxytriterpene carboxylic acids distributed widely in Olive,
Lagerstroemia speciose and other plants [20-22] (Fig. 1). To obtain a great quantity of the MA and
CA, the method of plant extraction is complicated and costly, however, and have been not
commercialized yet. Hence, the low-cost and efficient chemical synthesis of MA and CA become
an alternative method, using commercial oleanolic acid and ursolic acid as raw materials,
respectively [23, 24]. Studies have exhibited that MA and CA play a positive act in lowing blood
sugar [25, 26], but the application of them in clinical as therapeutic drugs is extremely limited by
their poor solubility and low bioavailability which are caused by the rigid skeleton. To improve the

solubility and bioactivity of pentacyclic triterpenic acids, a large number of researchers made great
efforts to modify the hydrophobic backbone through either introducing cyclodextrins [27, 28],
monosaccharide, disaccharide, oligosaccharide [29] and amino acid [30] into their parent
compounds or salifying [31]. As a sugar analog, 1-DNJ has both the characteristics of saturated
nitrogen heterocycles and sugar where the oxygen atom is substituted by nitrogen on the pyran ring,
mainly obtained from plant extraction and microbial fermentation. It has been demonstrated that 1-
DNJ is a highly potent α-glucosidase inhibitor causing side effects towards human body scarcely
[32]. Therefore, the introduction of 1-DNJ into parent compounds might be improved the bioactivity
and further play the effect of synergistic hypoglycemia. Meanwhile, piperazines are typical
saturated nitrogen heterocyclic compounds which are often introduced into drug molecules as
synergistic groups, thus beneficial to improve the pharmacokinetics properties, regulate acid-base
balance parameters and lipid-water partition coefficient of drugs [33-35]. In addition, it can also
improve the biological activity of drug molecules by forming hydrogen bonds or ionic bonds with
the target protein [36]. Zhao introduced piperazine into the C-10 site of dihydroartemisinin by ether
formation or esterification, and the results showed that all derivatives provided a better growth
inhibitory effect than dihydroartemisinin in human leukemia HL-60 cells, mouse lymphoma P388
and adriamycin resistant P388/Adr [37]. Here, taking all the facts into account, the first series of
MA (or CA) derivatives are synthesized, according to the principle of active splicing, by utilizing
α, ω-bromoalkanes as linkers to combine MA (or CA) with 1-DNJ. Subsequently, the measurement
of inhibitory activity of the MA (or CA)-1-DNJ derivatives towards α-glucosidase, does not fully
achieve the desired effects for improving the hypoglycemic activity of the lead compounds.
Consequently, piperazines are chosen to couple with MA (or CA) at C-28 site directly to prepare

the second series of compounds, and the α-glucosidase inhibitory activity indicates that some
products possess superior inhibition rate than that of the precursor MA (or CA) as well as acarbose.
In the end, after evaluating the α-glucosidase inhibition activities of all MA (or CA) derivatives, the
preliminary structure-activity relationship and inhibitory mechanism of the compounds have been
discussed.
2. Results and discussion
2.1. Chemistry
The highly efficient α-glucosidase inhibitor 1-DNJ was introduced at the C-28 position of MA
(or CA) by an esterification and a nucleophilic substitution reaction [38, 39], as shown in Scheme
1. MA (or CA) was first reacted with α, ω-bromoalkanes to generate a series of compounds 2a2h
(or 3a3h) in the presence of anhydrous potassium carbonate, and then treated with 1-DNJ via
nucleophilic substitution reaction to prepare MA (or CA)-DNJ conjugates. As outlined in Scheme
2, MA (or CA) was acetylated by acetic anhydride to obtain white solid 6 (or 7), which then
converted into the intermediates 10a10c (or 11a11c) by reaction with oxalyl chloride and
piperazines at the presence of triethylamine. Hydrolysis of 10a10c (or 11a11c) in 4N solution of
sodium hydroxide got the final compounds 12a12c (or 13a13c). The structure of all target
derivatives was characterized by 1H/13C NMR and HRMS.

R2
R2
R1
R1
OH
O
n Br
Br
n
Br
HO
HO
HO
HO
O
O
(i)
MA ( R1 = H, R2 = CH3
CA ( R1 = CH3, R2 = H )
)
2a-2h ( R1 = H, R2 = CH3, n= 2-6, 8, 10, 12 )
3a-3h ( R1 = CH3, R2 = H, n= 2-6, 8, 10, 12 )
R2
OH
R1
H
OH
N
HO
O
N
n
OH
OH
HO
OH
HO
HO
O
OH
(ii)
4a-4h ( R1 = H, R2 = CH3, n= 2-6, 8, 10, 12 )
5a-5h ( R1 = CH3, R2 = H, n= 2-6, 8, 10, 12 )
Scheme 1. Synthesis of pentacyclic dihydroxyterpene carboxylic acid derivatives 4a4h (5a5h).
Reagents and conditions: (i) K2CO3, DMF, rt, 24h; (ii) K2CO3, KI, N2, DMF, 50C, 24h.
R2
R2
R1
R2
R1
R1
Cl
OH
OH
AcO
AcO
O
(ii)
AcO
AcO
(i)
O
HO
HO
O
8 ( R1 = H, R2 = CH3
9 ( R1 = CH3, R2 = H )
)
6 ( R1 = H, R2 = CH3
7 ( R1 = CH3, R2 = H )
)
MA ( R1 = H, R2 = CH3
)
CA ( R1 = CH3, R2 = H )
R2
R1
R2
R1
Y
Y
HO
HO
(iv)
O
(iii)
AcO
AcO
O
12a-12c ( R1 = H, R2 = CH3, Y = N1-N3
13a-13c ( R1 = CH3, R2 = H, Y = N1-N3
)
)
10a-10c ( R1 = H, R2 = CH3, Y = N1-N3
11a-11c ( R1 = CH3, R2 = H, Y = N1-N3
)
)
N1=
N
NH
N3= HN
N
(CH2)2NH
N
N
(CH2)2OH
N2=
Scheme 2. Synthesis of pentacyclic dihydroxyterpene carboxylic acid derivatives 12a12c
(13a13c). Reagents and conditions: (i) acetic anhydride, Py, rt, 20h; (ii) oxalyl chloride, Et3N,
DCM, 0C25C, 24h; (iii) Et3N, DCM, piperazines, 0C25C, 3h; (iv) 4N NaOH,
CH3OH/THF, 25C, 1h.
2.2. Bioactivity
In order to investigate the inhibitory effect of the synthesized compounds on α-glucosidase, all
final products dissolving in DMSO were performed inhibition experiments in vitro. As the results

listed in Table 1, most of the compounds exhibit a certain inhibitory activity against α-glucosidase.
Among the first series of triterpenic acid-DNJ derivatives (4a4h, 5a5h), compound 4a (IC50 =
2041.4 µM), 4b (IC50 = 1468.4 µM), 4c (IC50 = 1718.4 µM) and 5a (IC50 = 1257.3 µM) featuring
the linker of alkyl chain (24 carbon atoms) are show lower IC50 than those of their leading
compound MA (IC50 = 2540.6 µM) and CA (IC50 = 1363.7 µM), respectively. However, with the
longer hydrophobic carbon chain (48 carbon atoms) embedding the molecular structure, the
inhibitory activity of the derivatives is lower than that of the parent compound MA or CA, such as
4d (IC50 = 3660.4 µM), 4f (IC50 = 3068.4 µM), 5b (IC50 = 1554.4 µM), 5c (IC50 = 1841.4 µM), 5d
(IC50 = 1381.8 µM) and 5f (IC50 = 1741.2 µM). Meanwhile, the solubility in the measurement
system is significantly dropped when the carbon chains of the derivatives contain 10 or 12 carbon
atoms (e.g. 4h, 4f, 5h, 5f), and the inhibition rate measured at a low concentration is less than the
precursors. Consequently, no alternative solvent system is suitable to determine the IC50 values of
these compounds. The introduction of 1-DNJ in the MA (or CA) structure elevates the solubility of
derivatives significantly in comparison with the triterpene acids. Regrettably, the inhibitory activity
of most derivatives coupling 1-DNJ is not enhanced compared to MA (or CA). The α-glucosidase
inhibitory activities of the products demonstrate that the carbon chain lengths of the linker between
triterpenic acid and 1-DNJ play a vital role in the hypoglycemic activity of the derivatives. It is
obvious that the inhibitory effect of derivatives with short linkers against α-glucosidase is superior
to that of the compounds containing overlong linkers. In addition, it is interesting that most of the
CA derivatives provide better inhibitory effects than those of MA analogues (e.g. 5a vs 4a, 5d vs
4d, 5f vs 4f). Pentacyclic dihydroxytriterpene carboxylic acid coupling with piperazines (i.e.
12a12c, 13a13c) belong to the second series of derivatives. The piperazine segment of

compounds with one free hydroxyl (12b: IC50 = 499.6 µM, 13b: IC50 = 660.7 µM) and amino groups
(12c: IC50 = 768.5 µM, 13c: IC50 = 819.2 µM) present higher inhibition activity notably than that of
MA (IC50 = 2540.6 µM) and CA (IC50 = 1363.7 µM). It is worthy note that the hypoglycemic
activity of compound 12b is superior to acarbose (IC50 = 606 µM). The results demonstrate that a
free hydroxyl or an amino group in piperazine as a substructure in the pentacyclic triterpene acids
derivatives can enhance the α-glucosidase inhibition activity of the modified compounds (e.g. 12b
vs 12a, 12c vs 12a, 13b vs 13a, 13c vs 13a). Besides, MA derivatives perform better bioactive than
that of CA counterparts on inhibition of α-glucosidase (e.g. 12b vs 13b, 12c vs 13c).
Table 1 IC50 values (µM) of the derivatives for the inhibition of α-glucosidase.
a
a
Products number
IC50
Products number
IC50
4a
4b
5a
5b
2041.4  20.2
1468.4  17.1
1718.4  8.4
3660.4  74
bNI
1257.3  13.5
1554.4 13
1841.4  20.4
1381.8  30
bNI
4c
5c
4d
5d
4e
5e
4f
5f
3068.4  2.8
1741.2  15.3
c
c
4g
/
5g
/
c
c
4h
/
5h
/
12a
12b
12c
Acarbose
MA
bNI
13a
13b
13c
1-DNJ
CA
bNI
499.6  2.3
768.5  12.3
606  11
660.7  13.5
819.2  14.7
142.2  3.6
1363.7  0.7
2540.6  68
a Values are the mean of four experiments.
b NI = NO Inhibition.
c The derivatives cannot dissolved in the solvent system of measurement.
Kinetics study was employed to explore the inhibitory mechanism of compounds on α-
glucosidase. Given the inhibitory similarity of the derivatives on α-glucosidase, the highly active
compound 12b is chosen as a representative for enzyme kinetics analysis. As shown in Fig. 2, the
increasing of inhibitor concentrations results in different slopes of the straight lines in the case of
certain substrate concentration. All the lines approximately intersect at one point on the x axis,

which define that the enzyme kinetics inhibitory mechanism of compound 12b belongs to the typical
non-competitive inhibition. Furthermore, the secondary plot of the slop versus various
concentrations of inhibitor 12b to give an estimate inhibition constant, Ki = 570 µM (Fig. 3).
Fig. 2. Lineweaver-Burk plot of 12b.
Fig. 3. The secondary plot between slop and concentrations of compound 12b.
2.3. Docking analysis
To shed light on the varied measurement results of the triterpene acids and their derivatives on
α-glucosidase inhibition activity, molecular docking simulation was performed to analyze the
binding mode of the compounds with the protein receptor. The more active compounds (4b, 5a, 12b

and 1-DNJ) and parent compounds were selected as the donators simultaneously. The molecule
docking results (Table 2) show that compounds 4b, 5a and 12b possess lower interaction energy
than the precursors, which indicate that the active compounds are binding closely with receptor of
α-glucosidase. Therefore, it means that their inhibitory activities higher than those of precursors. As
shown in Fig. 4, compound 12b establishes three hydrogen bonds through carbonyl and hydroxyl
group with the binding site residues Tyr464, Asn449 and Ser465, and forms hydrophobic
interactions with His447 and Tyr464 residues. The 1-DNJ segment of compound 4b constructs five
hydrogen bonds with residues including Ser465 (2), Asn449 (2) and Asp450, and the other entity
forms hydrophobic interactions with His447 and Tyr464 residues. As to compound 5a establishes
hydrogen bonding interactions with His447 and Asp450 residues via hydroxyl group, and forms
hydrophobic interactions with Val333 and Tyr464 residues. Precursor MA only forms hydrophobic
interactions with His447 and Tyr464 residues, and CA builds only one hydrogen bond through
carboxyl with the binding site Arg15 residue and forms hydrophobic interactions with His447
residue. The free hydroxyl groups of 1-DNJ construct five hydrogen bonds with the residues
Asp450 (2), Ile448, Asp446 and His447. In view of these facts, it can be suggested that the
synergistic modification of MA and CA increase the hydrogen bonding interactions between
derivatives and the receptor protein, which probably the principal reason that the inhibitory activity
of derivatives on α-glucosidase is superior to their parents. Fortunately, the docking results are good
consistent with the activities tested in vitro. Besides, the hydroxyl groups in the molecules
strengthen the interactions with target protein and play an important role in improving the
bioactivity. Therefore, it is expected to be the potential α-glucosidase inhibitors via incorporate the
active moieties of 1-DNJ and piperazines to the molecular framework of MA and CA.

Table 2 The docking results of 12b, 4b, 5a, CA, MA and 1-DNJ.
Compound
12b
 CDOCKER INTERACTION ENERGY (kcal/mol)
39.2597
47.4599
43.4789
30.5992
30.3889
23.7343
4b
5a
CA
MA
1-DNJ
Fig. 4. The diagram of molecular docking between the compound 12b, 4b, 5a, MA, CA, 1-DNJ

and α-glucosidase.
3. Conclusion
In summary, based on the principle of active splicing, a total of 22 pentacyclic tricarboxylic
acid-saturated nitrogen heterocycle compounds have been synthesized, and the α-glucosidase
inhibition activity of the synthesized compounds was performed in vitro. Among of the pentacyclic
tricarboxylic acid-piperazine derivatives, the inhibitory activity of the MA derivatives is higher than
that of the CA counterparts, wherein the inhibitory activity of the compound 12b (IC50 = 499.6 µM)
on α-glucosidase is stronger than that of acarbose (IC50 = 606 µM) and MA. Triterpenic acid-1-
DNJ conjugates such as 4a, 4b, 4c and 5a are exhibited lower IC50 than their leading compound
MA and CA, respectively. The derivatives of CA obtain better inhibitory effects than that of MA
analogues (e.g. CA vs MA, 5a vs 4a, 5d vs 4d, 5f vs 4f), but the inhibition of 5b and 5c is slightly
weaker than that of 4b and 4c, respectively. Nevertheless, it is fortunate that most of the second
series derivatives containing piperazine unit have superior α-glucosidase inhibition activities with
respect to the precursors. Molecular docking simulation further manifests that the increased
bioactivity of the derivatives is attributed to the introduction of active groups (i.e. 1-DNJ and
piperazines) into the MA (or CA) which enhances the hydrogen bond interaction between the
compounds and α-glucosidase. Moreover, the result of kinetics study indicates that the inhibition
mechanism of the derivatives is non-competitive inhibition.
4. Experimental section
All of the chemicals and solvents were purchased from commercial vendors and were not
further purified unless otherwise stated. The described reactions were monitored by Thin layer
chromatography (TLC) using silica gel GF254 plates, which were visualized by heating the TLC

plates sprayed with 5% sulfuric acid in ethanol. The compounds were purified by column
chromatography on silica gel (200-300 mesh) with petroleum ether and ethyl acetate or
1
dichloromethane and methanol as eluent. H and 13C NMR spectra were taken on a Bruker
spectrometer at 400 MHz (1H NMR), 100 MHz (13C NMR) using CDCl3 or DMSO-d6 as solvents,
and chemical shifts (δ) were reported in ppm, coupling constants (J) were presented in hertz. High
resolution mass spectrometry (HRMS) were acquired from Finnigan MAT 95 XP mass spectrometer.
α-Glucosidase (CAS: 9001-42-7) derived from Saccharomyces cerevisiae was purchased from
Sigma. Acarbose and 4-nitrophenyl-α-D-glucopyranoside were obtained from Aladdin.
4.1. Synthesis of MA and CA
MA and CA were prepared by previous methods in the literature[23, 24].
4.2. Synthesis of MA/CA-1-DNJ derivatives
4.2.1. 28-(2-Bromoethyl) maslinic acid ester (2a)
MA (534 mg, 1.13 mmol) and anhydrous potassium carbonate (468 mg, 3.39 mmol) were
resolved in waterless DMF (10 mL), and the mixture was stirred for 30 minutes at room temperature,
then dripped 1, 2-dibromoethane (1.5 mL). When TLC analyzed that MA was consumed completely,
quenched the reaction by water and extracted with ethyl acetate. The upper layer was added
anhydrous Na2SO4 to absorbing water, then filtrated and evaporated to dryness. The residue was
purified by column chromatography on silica gel to obtain 2a as a white flake solid. Yield 83%, mp:
175 C176 C.1H NMR (400 MHz, CDCl3):  5.30 (t, J = 8 Hz, 1H), 4.264.37 (m, 2H), 3.653.72
(m, 1H), 3.48 (t, J = 12 Hz, 2H), 2.98 (d, J = 12 Hz, 1H), 2.222.27 (m, 1H), 1.901.98 (m, 3H),
1.641.73 (m, 4H), 1.531.59 (m, 4H), 1.341.46 (m, 4H), 1.181.31 (m, 6H), 1.13 (s, 3H), 1.02
(s, 3H), 0.97 (s, 3H), 0.90 (d, J = 12 Hz, 6H), 0.82 (s, 3H), 0.73 (s, 3H). 13C NMR (100 MHz,

CDCl3):  176.81, 143.05, 121.97, 83.43, 68.45, 63.16, 54.81, 47.10, 46.36, 45.94, 45.30, 41.26,
40.77, 38.97, 38.68, 37.80, 33.37, 32.58, 32.15, 31.96, 30.20, 28.51, 28.13, 27.16, 25.39, 23.09,
23.00, 22.44, 17.86, 16.60, 16.26, 16.13. HRMS (ESI, m/z): [M + Na]+ Calcd for C32H51BrNaO4:
601.2863; found: 601.2863.
4.2.2. 28-(3-Bromopropyl) maslinic acid ester (2b)
Compound 2b was a white flake solid prepared from MA and 1,3-dibromopropane by using
the same method established for 2a. Yield 90%, mp: 134 C136 C. 1H NMR (400 MHz, CDCl3):
 5.27 (t, J = 8 Hz, 1H), 4.134.17 (m, 2H), 3.653.72 (m, 1H), 3.45 (t, J = 12 Hz, 2H), 2.98 (d, J
= 12 Hz, 1H), 2.122.18 (m, 2H), 1.891.99 (m, 5H), 1.591.70 (m, 6H), 1.161.52 (m, 10H), 1.13
(s, 3H), 1.02 (s, 3H), 0.97 (s, 3H), 0.90 (d, J = 8 Hz, 6H), 0.82 (s, 3H), 0.73 (s, 3H). 13C NMR (100
MHz, CDCl3):  176.99, 143.31, 121.84, 83.44, 68.44, 61.35, 54.82, 47.11, 46.31, 45.94, 45.30,
41.29, 40.89, 38.94, 38.68, 37.81, 33.35, 32.57, 32.16, 32.00, 31.30, 30.19, 28.99, 28.13, 27.11,
25.41, 23.11, 23.03, 22.54, 17.85, 16.69, 16.24, 16.11. HRMS (ESI, m/z): [M + K]+ Calcd for
C33H53BrKO4: 631.2759; found: 631.2759.
4.2.3. 28-(4-Bromobutyl) maslinic acid ester (2c)
Compound 2c was a white flake solid prepared from MA and 1,4-dibromobutane by using the
same method established for 2a. Yield 88%, mp: 130 C131 C. 1H NMR (400 MHz, CDCl3): 
5.29 (s, 1H), 4.04 (s, 2H), 3.653.72 (m,1H), 3.43 (s, 2H), 2.843.00 (m, 1H), 2.192.25 (m, 2H),
1.921.97 (m, 6H), 1.521.77 (m, 10H), 1.251.36 (m, 3H), 1.13 (s, 4H), 0.821.03 (m, 18H), 0.72
(s, 3H). 13C NMR (100 MHz, CDCl3):  177.21, 143.32, 121.79, 83.40, 68.43, 62.72, 54.79, 47.08,
46.22, 45.88, 45.33, 41.25, 40.79, 38.91, 38.68, 37.80, 33.36, 32.59, 32.12, 32.01, 30.21, 29.05,
28.13, 27.09, 26.86, 25.42, 23.12, 22.98, 22.50, 17.84, 16.62, 16.27, 16.11. HRMS (ESI, m/z): [M

+ K]+ Calcd for C34H55BrKO4: 645.2915; found: 645.2916.
4.2.4. 28-(5-Bromoamyl) maslinic acid ester (2d)
Compound 2d was a white flake solid prepared from MA and 1,5-dibromopentane by using
the same method established for 2a. Yield 84%, mp: 137 C138 C. 1H NMR (400 MHz, CDCl3):
 5.27 (t, J = 8 Hz, 1H), 4.004.04 (m, 2H), 3.653.71 (m, 1H), 3.39 (t, J = 12 Hz, 2H), 2.98 (d, J
= 8 Hz, 1H), 2.232.27 (m, 2H),1.951.99 (m, 2H), 1.861.92 (m, 4H), 1.641.69 (m, 4H),
1.591.62 (m, 4H), 1.511.55 (m, 4H), 1.361.46 (m, 4H), 1.251.33 (m, 4H), 1.161.20 (m, 2H),
1.12 (s, 3H), 0.97 (s, 3H), 0.89 (d, J = 12 Hz, 6H), 0.81 (s, 3H), 0.72 (s, 3H). 13C NMR (100 MHz,
CDCl3):  177.26, 143.39, 121.71, 83.43, 68.44, 63.35, 54.81, 47.11, 46.21, 45.92, 45.38, 41.26,
40.80, 38.93, 38.68, 37.81, 33.40, 33.00, 32.60, 32.15, 32.02, 31.79, 30.22, 28.14, 27.33, 27.12,
25.41, 24.31, 23.13, 23.01, 22.51, 17.86, 16.59, 16.27, 16.12. HRMS (ESI, m/z): [M + H]+ Calcd
for C35H58BrO4: 621.3513; found: 621.3513.
4.2.5. 28-(6-Bromohexyl) maslinic acid ester (2e)
Compound 2e was a white flake solid prepared from MA and 1,6-dibromohexane by using the
same method established for 2a. Yield 87%, mp: 176 C178 C. 1H NMR (400 MHz, CDCl3): 
5.26 (t, J = 8 Hz, 1H), 3.994.02 (m, 2H), 3.663.71 (m, 1H), 3.38 (t, J = 16 Hz, 2H), 2.983.01
(m, 1H), 2.182.24 (m, 1H), 1.951.99 (m, 2H), 1.831.92 (m, 5H), 1.581.69 (m, 9H), 1.431.52
(m, 6H), 1.361.40 (m, 2H), 1.271.33 (m, 2H), 1.161.20 (m, 2H), 1.12 (s, 3H), 1.02 (s, 3H), 0.97
(s, 3H), 0.89 (d, J = 12 Hz, 6H), 0.81 (s, 3H), 0.72 (s, 3H). 13C NMR (100 MHz, CDCl3):  177.28,
143.37, 121.67, 83.34, 68.40, 63.53, 54.79, 47.07, 46.17, 45.90, 45.36, 41.24, 40.78, 38.90, 38.70,
37.77, 33.39, 33.14, 32.61, 32.18, 32.00, 30.21, 28.15, 27.96, 27.28, 27.09, 25.41, 24.80, 23.13,
22.99, 22.50, 17.85, 16.59, 16.30, 16.11. HRMS (ESI, m/z): [M + H]+ Calcd for C36H60BrO4:

635.3670; found: 635.3671.
4.2.6. 28-(8-Bromooctyl) maslinic acid ester (2f)
Compound 2f was a white flake solid prepared from MA and 1,8-dibromooctane by using the
same method established for 2a. Yield 85%, mp: 156 C158 C. 1H NMR (400 MHz, CDCl3): 
5.26 (t, J = 8 Hz, 1H), 3.964.03 (m, 2H), 3.653.71 (m, 1H), 3.38 (t, J = 12 Hz, 2H), 2.98 (d, J =
8 Hz, 1H), 2.232.29 (m, 1H), 1.831.99 (m, 7H), 1.591.72 (m, 9H), 1.391.52 (m, 5H), 1.251.32
(m, 10H), 1.161.20 (m, 1H), 1.12 (s, 1H), 1.02 (s, 1H), 0.97 (s,1H), 0.89 (d, J = 12 Hz, 6H), 0.81
(s, 3H), 0.72 (s, 3H). 13C NMR (100 MHz, CDCl3):  177.28, 143.39, 121.66, 83.39, 68.42, 63.71,
54.80, 47.09, 46.16, 45.91, 45.38, 41.24, 40.78, 38.92, 38.68, 37.79, 33.40, 32.61, 32.28, 32.15,
31.99, 30.21, 28.51, 28.21, 28.13, 28.07, 27.59, 27.10, 25.47, 25.40, 23.12, 22.99, 22.50, 17.86,
16.58, 16.27, 16.11. HRMS (ESI, m/z): [M - H]- Calcd for C38H62BrO4: 661.3837; found: 661.3815.
4.2.7. 28-(10-Bromodecyl) maslinic acid ester (2g)
Compound 2g was a white flake solid prepared from MA and 1,10-dibromodecane by using
the same method established for 2a. Yield 86%, mp: 123 C125 C. 1H NMR (400 MHz, CDCl3):
 5.26 (t, J = 8 Hz, 1H), 3.984.02 (m, 2H), 3.653.71 (m, 1H), 3.38 (t, J = 16 Hz, 1H), 2.98 (d, J
= 12 Hz, 1H), 2.222.27 (m, 1H), 1.811.99 (m, 7H), 1.551.69 (m, 8H), 1.361.52 (m, 7H),
1.291.33 (m, 12H), 1.161.20 (m, 2H), 1.12 (s, 3H), 1.02 (s, 3H), 0.97 (s, 3H), 0.89 (d, J = 12 Hz,
6H), 0.82 (s, 3H), 0.72 (s, 3H). 13C NMR (100 MHz, CDCl3):  177.31, 143.40, 121.65, 83.38, 68.42,
63.77, 54.78, 47.09, 46.15, 45.89, 45.37, 41.23, 40.77, 38.90, 38.68, 37.78, 33.50, 33.40, 32.62,
32.32, 32.14, 31.98, 30.22, 28.98, 28.87, 28.67, 28.27, 28.12, 27.67, 27.09, 25.56, 25.41, 23.13,
22.99, 22.49, 17.85, 16.58, 16.29, 16.11. HRMS (ESI, m/z): [M + H]+ Calcd for C40H68BrO4:
691.4296; found: 691.4285.

4.2.8. 28-(12-Bromododecyl) maslinic acid ester (2h)
Compound 2h was a white flake solid prepared from MA and 1,12-dibromododecane by using
the same method established for 2a. Yield 83%, mp: 119 C120 C. 1H NMR (400 MHz, CDCl3) :
 5.26 (t, J = 8 Hz, 1H), 3.984.03 (m, 2H), 3.663.72 (m, 1H), 3.39 (t, J = 12 Hz, 2H), 2.99 (d, J
= 8 Hz, 1H), 1.832.00 (m, 6H), 1.571.69 (m, 9H), 1.361.52 (m, 7H), 1.251.33 (m, 18H),
1.161.20 (m, 1H), 1.13 (s, 3H), 1.03 (s, 3H), 0.97 (s, 3H), 0.90 (d, J = 8 Hz, 6H), 0.82 (s, 3H), 0.72
(s, 3H). 13C NMR (100 MHz, CDCl3):  177.32, 143.39, 121.65, 83.36, 68.41, 63.80, 54.78, 47.08,
46.15, 45.89, 45.37, 41.23, 40.76, 38.90, 38.69, 37.77, 33.54, 33.40, 32.63, 32.34, 32.13, 31.98,
30.22, 29.05, 28.71, 28.29, 28.13, 27.69, 27.09, 25.57, 25.41, 23.13, 22.98, 22.48, 17.86, 16.57,
16.30, 16.10. HRMS (ESI, m/z): [M + K]+ Calcd for C42H71BrKO4: 757.4167; found: 757.4203.
4.2.9. 28-(2-Bromoethyl) corosolic acid ester (3a)
Compound 3a was a white foamy solid prepared from CA and 1,2-dibromoethane by using the
same method established for 2a. Yield 90%, mp: 103 C104 C. 1H NMR (400 MHz, CDCl3): 
5.26 (t, J = 8 Hz, 1H), 4.284.32 (m, 2H), 3.663.71 (m, 1H), 3.46 (t, J = 12 Hz, 2H), 2.98 (d, J =
8 Hz, 1H), 2.22 (d, J = 12 Hz, 1H), 1.922.01 (m, 4H), 1.751.82 (m, 1H), 1.681.71 (m, 2H),
1.481.63 (m, 4H), 1.251.41 (m, 7H), 1.08 (s, 3H), 0.931.02 (m, 9H), 0.810.86 (m, 6H), 0.75
(s, 3H). 13C NMR (100 MHz, CDCl3):  176.65, 137.47, 125.15, 83.28, 68.40, 63.20, 54.79, 52.27,
47.74, 46.99, 46.19, 41.61, 39.15, 38.74, 38.55, 38.34, 37.69, 36.18, 32.44, 30.14, 28.53, 28.21,
27.46, 23.63, 23.07, 22.89, 20.68, 17.84, 16.67, 16.51, 16.39, 16.26. HRMS (ESI, m/z): [M + Na]+
Calcd for C32H51BrNaO4: 601.2863; found: 601.2863.
4.2.10. 28-(2-Bromopropyl) corosolic acid ester (3b)
Compound 3b was a white foamy solid prepared from CA and 1,3-dibromopropane by using

the same method established for 2a. Yield 88%, mp: 104 C105 C. 1H NMR (400 MHz, CDCl3):
 5.23 (t, J = 8 Hz, 1H), 4.054.19 (m, 2H), 3.663.72 (m, 1H), 3.44 (t, J = 16 Hz, 2H), 2.98 (d, J
= 12 Hz, 1H), 2.112.25 (m, 5H), 1.932.03 (m, 4H), 1.731.81 (m, 1H), 1.651.69 (m, 3H),
1.471.64 (m, 5H), 1.251.42 (m, 5H), 1.08 (s, 3H), 1.03 (s, 3H), 0.99 (s, 3H), 0.93 (d, J = 8 Hz,
3H), 0.84 (d, J = 8 Hz, 3H), 0.82 (s, 3H), 0.76 (s, 3H). 13C NMR (100 MHz, CDCl3):  176.84,
137.87, 124.93, 83.43, 68.46, 61.33, 54.79, 52.40, 47.69, 47.03, 46.13, 41.65, 39.12, 38.67, 38.57,
38.38, 37.73, 36.24, 32.44, 31.29, 30.13, 29.12, 28.16, 27.41, 23.73, 23.09, 22.92, 20.66, 17.81,
16.76, 16.51, 16.30, 16.25. HRMS (ESI, m/z): [M + H]+ Calcd for C33H54BrO4: 593.3200; found:
593.3200.
4.2.11. 28-(4-Bromobutyl) corosolic acid ester (3c)
Compound 3c was a white foamy solid prepared from CA and 1,4-dibromobutane by using the
same method established for 2a. Yield 86%, mp: 78 C79 C. 1H NMR (400 MHz, CDCl3):  5.23
(t, J = 8 Hz, 1H), 3.954.07 (m, 2H), 3.663.72 (m, 1H), 3.40 (t, J = 16 Hz, 1H), 2.98 (d, J = 8 Hz,
1H), 2.20 (d, J = 12 Hz, 1H), 1.902.02 (m, 7H), 1.601.79 (m, 7H), 1.461.58 (m, 5H), 1.251.41
(m, 5H), 1.07 (s, 3H), 1.02 (s, 3H), 0.98 (s, 3H), 0.93 (d, J = 4 Hz, 3H), 0.82 (t, J = 16 Hz, 6H), 0.74
(s, 3H). 13C NMR (100 MHz, CDCl3):  177.04, 137.82, 124.90, 83.41, 68.45, 62.70, 54.79, 52.33,
48.08, 47.01, 46.11, 41.49, 39.12, 38.67, 38.58, 38.37, 37.73, 36.25, 32.55, 32.44, 30.15, 29.02,
28.17, 27.41, 26.83, 23.70, 23.08, 22.86, 20.68, 17.81, 16.68, 16.52, 16.31, 16.26. HRMS (ESI,
m/z): [M + H]+ Calcd for C34H56BrO4: 607.3357; found: 607.3357.
4.2.12. 28-(5-Bromoamyl) corosolic acid ester (3d)
Compound 3d was a white foamy solid prepared from CA and 1,5-dibromopentane by using
the same method established for 2a. Yield 85%, mp: 84 C85 C. 1H NMR (400 MHz, CDCl3): 

5.23 (t, J = 8 Hz, 1H), 3.98 (t, J = 8 Hz, 2H), 3.663.72 (m, 1H), 3.39 (t, J = 16 Hz, 2H), 2.98 (d, J
= 12 Hz, 1H), 2.21 (d, J = 12 Hz, 2H), 1.862.02 (m, 7H), 1.731.81 (m, 2H)，1.571.68 (m, 7H),
1.471.55 (m, 6H), 1.301.41 (m, 4H), 1.25 (s, 1H), 1.07 (s, 3H), 1.02 (s, 3H), 0.98 (s, 3H), 0.93
(d, J = 4 Hz, 3H), 0.82 (t, J = 12 Hz, 3H), 0.74 (s, 3H). 13C NMR (100 MHz, CDCl3):  177.05,
137.84, 124.85, 83.46, 68.48, 63.32, 54.80, 52.35, 47.58, 47.03, 46.16, 41.64, 39.15, 38.59, 38.38,
37.74, 36.25, 32.95, 32.46, 31.79, 30.18, 29.20, 28.16, 27.45, 27.29, 24.31, 23.71, 23.06, 22.89,
20.67, 17.82, 16.66, 16.52, 16.27. HRMS (ESI, m/z): [M + H]+ Calcd for C35H58BrO4: 621.3513;
found: 621.3513.
4.2.13. 28-(6-Bromohexyl) corosolic acid ester (3e)
Compound 3e was a white foamy solid prepared from CA and 1,6-dibromohexane by using
the same method established for 2a. Yield 88%, mp: 79 C80 C. 1H NMR (400 MHz, CDCl3): 
5.24 (t, J = 8 Hz, 1H), 3.964.00 (m, 2H), 3.663.72 (m, 1H), 3.42 (t, J = 12 Hz, 2H), 3.01 (d, J =
12 Hz, 1H), 2.172.26 (m, 3H), 1.982.02 (m, 2H), 1.921.95 (m, 2H), 1.841,88 (m, 2H),
1.761.81 (m, 1H), 1.68 (s, 3H), 1.571.64 (m, 4H), 1.461.55 (m, 6H), 1.301.39 (m, 6H), 1.07
(s, 3H), 1.02 (s, 3H), 0.98 (s, 3H), 0.94 (d, J = 4 Hz, 3H), 0.86 (t, J = 16 Hz, 6H), 0.74 (s, 3H). 13
C
NMR (100 MHz, CDCl3):  177.58, 138.34, 125.31, 83.92, 68.96, 64.01, 55.31, 52.86, 48.07, 47.53,
46.65, 42.14, 39.64, 39.17, 39.08, 38.88, 38.23, 36.74, 33.60, 32.97, 32.66, 30.68, 28.66, 28.43,
27.94, 27.79, 25.30, 24.21, 23.55, 23.37, 21.16, 18.32, 17.17, 17.01, 16.80, 16.74. HRMS (ESI,
m/z): [M + K]+ Calcd for C36H59BrKO4: 673.3228; found: 673.3223.
4.2.14. 28-(8-Bromooctyl) corosolic acid ester (3f)
Compound 3f was a white foamy solid prepared from CA and 1,8-dibromooctane by using the
same method established for 2a. Yield 84%, mp: 73 C74 C. 1H NMR (400 MHz, CDCl3):  5.23

(s, 1H), 3.954.00 (m, 2H), 3.673.72 (m, 1H), 3.38 (t, J = 16 Hz, 2H), 2.98 (d, J = 12 Hz, 1H),
2.212.24 (d, J = 12 Hz, 1H), 1.772.02 (m, 8H), 1.431.69 (m, 15H), 1.32 (s, 9H), 1.02 (d, J = 20
Hz, 6H), 0.94 (d, J = 16 Hz, 6H), 0.82 (t, J = 12 Hz, 6H), 0.74 (s, 3H). 13C NMR (100 MHz, CDCl3):
 177.15, 137.82, 124.82, 83.41, 68.47, 63.72, 54.81, 52.35, 47.55, 47.04, 46.16, 41.63, 39.14, 38.68,
38.60, 38.39, 37.74, 36.24, 33.42, 32.48, 32.28, 30.21, 28.54, 28.20, 28.05, 27.61, 27.45, 25.49,
23.72, 23.08, 22.88, 20.71, 17.84, 16.67, 16.55, 16.34, 16.28. HRMS (ESI, m/z): [M + Na]+ Calcd
for C38H63BrNaO4: 685.3802; found: 685.3806.
4.2.15. 28-(10-Bromodecyl) corosolic acid ester (3g)
Compound 3g was a white foamy solid prepared from CA and 1,10-dibromodecane by using
the same method established for 2a. Yield 82%, mp: 71 C72 C. 1H NMR (400 MHz, CDCl3): 
5.23 (t, J = 8 Hz, 1H), 3.944.00 (m, 2H), 3.663.72 (m, 1H), 3.39 (t, J = 12 Hz, 2H), 2.98 (d, J =
12 Hz, 1H), 2.21 (d, J = 12 Hz, 1H), 1.922.02 (m, 4H), 1.811.87 (m, 2H), 1.741.78 (m, 1H),
1.381.68 (m, 15H), 1.291.35 (m, 14H), 1.07 (s, 3H), 1.03 (s, 3H), 0.98 (s, 3H), 0.94 (s, 3H), 0.82
(t, J = 16 Hz, 6H), 0.74 (s, 3H). 13C NMR (100 MHz, CDCl3):  177.31, 137.82, 124.80, 83.43,
68.47, 63.78, 54.79, 52.33, 47.54, 47.02, 46.14, 41.62, 39.12, 38.66, 38.59, 38.38, 37.73, 36.23,
33.51, 32.46, 32.33, 30.20, 28.96, 28.88, 28.68, 28.26, 28.16, 28.08, 27.68, 27.43, 25.57, 23.70,
23.07, 22.86, 20.70, 17.83, 16.66, 16.54, 16.32, 16.26. HRMS (ESI, m/z): [M + K]+ Calcd for
C40H67BrKO4: 729.3854; found: 729.3855.
4.2.16. 28-(12-Bromododecyl) corosolic acid ester (3h)
Compound 3h (yield 81%) was a white foamy solid prepared from CA and 1,12-
dibromododecane by using the same method established for 2a. Yield 81%, mp: 65 C66 C. 1H
NMR (400 MHz, CDCl3):  5.21 (t, J = 8 Hz, 1H), 3.943.99 (m, 2H), 3.663.71 (m, 1H), 3.38 (t,

J = 12 Hz, 2H), 2.97 (d, J = 8 Hz, 1H), 2.592.65 (m, 1H), 2.20 (d, J = 12 Hz, 1H), 1.912.01 (m,
5H), 1.761.85 (m, 4H), 1.411.67 (m, 14H), 1.261.31 (m, 16H), 1.01 (d, J = 20 Hz, 6H), 0.93 (d,
J = 16 Hz, 6H), 0.80 (t, J = 20 Hz, 6H), 0.73 (s, 3H). 13C NMR (100 MHz, CDCl3):  177.16, 137.81,
124.81, 83.38, 68.44, 63.81, 54.79, 52.32, 47.53, 47.02, 46.14, 41.61, 39.12, 38.69, 38.59, 38.38,
37.72, 36.22, 33.53, 32.46, 32.34, 30.20, 29.05, 28.72, 28.29, 28.18, 28.08, 27.69, 27.43, 25.58,
23.70, 23.07, 22.87, 20.71, 17.83, 16.65, 16.54, 16.34, 16.24. HRMS (ESI, m/z): [M + K]+ Calcd
for C42H71BrKO4: 757.4167; found: 757.4160.
4.2.17. 28-[2-(1-Deoxynojirimycin)-ethyl] maslinic acid ester (4a)
To a solution of compound 2a (1.27 g, 2.19 mmol) anhydrous K2CO3 (251 mg, 6.57 mmol)
and 1-deoxynojirimycin (714 mg, 4.38 mmol) in dry DMF (15 mL) which was stirred for 15 minutes,
then added potassium iodide (2.18 g, 12.74 mmol) in a nitrogen atmosphere and left standing
overnight at 50 C. The reaction was quenched by 1 N HCl, diluted with water and ethyl acetate,
and combined organic layer was dried over anhydrous Na2SO4, concentrated and dried in vacuo.
The crude product was chromatographed on silica gel to give a white solid 4a. Yield 52%, mp: 173
C174 C. 1H NMR (400 MHz, DMSO-d6):  5.19 (s, 1H), 4.764.78 (m, 2H), 4.70 (s, 1H), 4.40
(s, 1H), 4.32 (s, 1H), 4.25 (s, 1H), 4.074.10 (m, 1H), 3.87-3.90 (m, 1H), 3.773.80 (m, 1H),
3.513.54 (m, 1H), 3.163.20 (m, 1H), 2.892.99 (m, 3H), 2.732.79 (m, 3H), 2.042.11 (m, 2H),
1.901.97 (m, 1H), 1.821.85 (m, 1H), 1.721.75 (m, 1H), 1.561.64 (m, 3H), 1.481.52 (m, 2H),
1.321.41 (m, 5H), 1.23 (s, 3H), 1.07 (s, 3H), 0.90 (d, J = 16 Hz, 12H), 0.68 (s, 3H), 0.63 (s, 3H).
13C NMR (100 MHz, DMSO-d6):  177.23, 143.99, 122.48, 82.81, 79.69, 71.30, 69.90, 67.70, 66.92,
61.98, 59.98, 58.16, 55.31, 50.72, 47.62, 47.36, 46.47, 46.04, 41.76, 41.31, 38.19, 33.76, 33.33,
32.77, 32.55, 31.49, 30.91, 29.34, 27.66, 26.27, 23.96, 23.54, 23.09, 22.60, 18.58, 17.65, 17.26,

16.84. HRMS (ESI, m/z): [M + K]+ Calcd for C38H63NKO8: 700.4185; found: 700.4185.
4.2.18. 28-[3-(1-Deoxynojirimycin)-propyl] maslinic acid ester (4b)
Compound 4b was a white solid prepared from 2b and 1-DNJ by using the same method
established for 4a. Yield 50%, mp: 186 C187 C. 1H NMR (400 MHz, DMSO-d6):  5.18 (s, 1H),
4.854.91 (m, 2H), 4.43 (d, J = 20 Hz, 2H), 3.94 (t, J = 12 Hz, 2H), 3.693.72 (m, 1H), 3.563.58
(m, 1H), 3.063.08 (m, 1H), 2.942.97 (m, 1H), 2.712.78 (m, 4H), 1.911.95 (m, 1H), 1.801.83
(m, 2H), 1.661.75 (m, 7H), 1.581.61 (m, 2H), 1.491.51 (m, 3H), 1.391.42 (m, 2H), 1.281.31
(m, 2H), 1.21 (s, 3H), 1.07(s, 3H), 0.90 (t, J = 16 Hz, 12H), 0.68 (s, 3H), 0.63 (s, 3H). 13C NMR
(100 MHz, DMSO-d6):  177.19, 144.15, 122.40, 82.89, 79.41, 70.94, 69.55, 67.79, 67.29, 62.90,
59.25, 57.15, 55.37, 49.51, 47.67, 47.42, 46.62, 46.08, 41.91, 41.52, 38.23, 33.86, 33.38, 32.90,
32.65, 30.97, 29.42, 27.73, 26.24, 24.54, 23.97, 23.64, 23.21, 18.63, 17.74, 17.36, 16.90. HRMS
(ESI, m/z): [M + H]+ Calcd for C39H66NO8: 676.4783; found: 676.4783.
4.2.19. 28-[4-(1-Deoxynojirimycin)-butyl] maslinic acid ester (4c)
Compound 4c was a white solid prepared from 2c and 1-DNJ by using the same method
established for 4a. Yield 50%, mp: 186 C187 C. Yield 52%, mp: 155 C156 C. 1H NMR (400
MHz, DMSO-d6):  5.18 (s, 1H), 4.654.70 (m, 2H), 4.31 (d, J = 32 Hz, 2H), 3.903.96 (m, 2H),
3.693.71 (m, 1H), 3.543.58 (m, 1H), 3.043.07 (m, 1H), 2.922.94 (m, 1H), 2.722.79 (m, 4H),
1.941.98 (m, 2H), 1.821.83 (m, 2H), 1.731.77(m, 2H), 1.551.62 (m, 5H), 1.481.52 (m, 7H),
1.401.43 (m, 3H), 1.281.32 (m, 2H), 1.23(s, 2H), 1.08 (s, 3H), 0.91(t, J = 20 Hz, 12H), 0.69 (s,
3H), 0.64 (s, 3H). 13C NMR (100 MHz, DMSO-d6):  177.18, 144.14, 122.42, 82.88, 79.69, 71.18,
69.80, 67.78, 67.12, 64.31, 59.46, 57.24, 55.37, 52.23, 47.67, 47.43, 46.64, 46.07, 41.92, 41.52,
38.24, 33.85, 33.36, 32.93, 32.75, 30.98, 29.41, 27.68, 26.84, 26.25, 23.95, 23.64, 23.20, 21.62,

18.63, 17.72, 17.37, 16.91. HRMS (ESI, m/z): [M + H]+ Calcd for C40H68NO8: 690.4939; found:
690.4940.
4.2.20. 28-[5-(1-Deoxynojirimycin)-amyl] maslinic acid ester (4d)
Compound 4d was a white solid prepared from 2d and 1-DNJ by using the same method
established for 4a. Yield 50%, mp: 131 C132 C. 1H NMR (400 MHz, DMSO-d6):  5.18 (s, 1H),
4.664.72 (m, 2H), 4.274.37 (m, 2H), 3.913.93 (m, 2H), 3.693.72 (m, 1H), 3.513.55 (m, 2H),
3.183.21 (m, 1H), 3.013.04 (m, 1H), 2.882.92 (m, 2H), 2.782.80 (m, 1H), 2.722.86 (m, 2H),
1.931.97 (m, 3H), 1.831.81 (m, 2H), 1.731.75 (m, 1H), 1.591.62 (m, 2H), 1.521.55 (m, 4H),
1.481.50 (m, 2H), 1.381.40 (m, 7H), 1.291.32 (m, 2H), 1.23 (s, 2H), 1.08 (s, 3H), 0.91 (t, J =
20 Hz, 12H), 0.69 (s, 3H), 0.64 (s, 3H). 13C NMR (100 MHz, DMSO-d6):  177.05, 143.98, 122.29,
82.72, 79.58, 71.18, 69.77, 67.62, 67.21, 64.14, 59.66, 57.26, 55.23, 52.51, 47.51, 47.31, 46.50,
45.91, 41.76, 41.39, 38.10, 33.68, 33.23, 32.78, 32.60, 30.85, 29.27, 28.54, 27.52, 27.11, 26.11,
24.62, 24.04, 23.82, 23.51, 23.04, 18.50, 17.59, 17.25, 16.78. HRMS (ESI, m/z): [M + H]+ Calcd
for C41H70NO8: 704.5096; found: 704.5096.
4.2.21. 28-[6-(1-Deoxynojirimycin)-hexyl] maslinic acid ester (4e)
Compound 4e was a white solid prepared from 2e and 1-DNJ by using the same method
established for 4a. Yield 45%, mp: 158 C159 C. 1H NMR (400 MHz, DMSO-d6):  5.18 (s, 1H),
4.674.72 (m, 2H), 4.274.37 (m, 2H), 3.903.94 (m, 2H), 3.683.70 (m, 1H), 3.533.56 (m, 1H),
3.193.21 (m, 1H), 3.013.05 (m, 1H), 2.882.92 (m, 1H), 2.762.80 (m, 2H), 2.712.74 (m, 1H),
1.911.97 (m, 3H), 1.811.83 (m, 2H), 1.721.76 (m, 1H), 1.581.65 (m, 3H), 1.481.54 (m, 6H),
1.291.42 (m, 11H), 1.181.22 (m, 3H), 1.08 (s, 3H), 0.91 (t, J = 20 Hz, 12H), 0.69 (s, 3H), 0.64
(s, 3H). 13C NMR (100 MHz, DMSO-d6):  177.19, 144.15, 122.41, 82.87, 79.71, 71.27, 69.89,

67.77, 67.23, 64.25, 59.53, 57.38, 55.38, 52.66, 47.65, 47.45, 46.65, 46.06, 41.91, 41.53, 38.24,
33.83, 33.36, 32.94, 32.75, 30.98, 29.41, 28.72, 27.67, 27.18, 26.24, 26.18, 25.08, 23.94, 23.65,
23.18, 18.64, 17.71, 17.38, 16.91. HRMS (ESI, m/z): [M + H]+ Calcd for C42H72NO8: 718.5252;
found: 718.5252.
4.2.22. 28-[8-(1-Deoxynojirimycin)-octyl] maslinic acid ester (4f)
Compound 4f was a white solid prepared from 2f and 1-DNJ by using the same method
established for 4a. Yield 47%, mp: 134 C135 C. 1H NMR (400 MHz, DMSO-d6):  5.17 (s, 1H),
4.694.73 (m, 2H), 4.284.37 (m, 2H), 3.903.94 (m, 2H), 3.673.71 (m, 1H), 3.543.57 (m, 1H),
3.023.05 (m, 1H), 2.882.93 (m, 1H), 2.712.80 (m, 4H), 1.911.97 (m, 3H), 1.811.83 (m, 2H),
1.721.76 (m, 1H), 1.581.62 (m, 1H), 1.491.55 (m, 6H), 1.411.44 (m, 2H), 1.351.38 (m, 3H),
1.281.32 (m, 3H), 1.24 (m, 9H), 1.15-1.19 (m, 3H), 1.08 (s, 3H), 0.91 (t, J = 20.0 Hz, 12H), 0.69
(s, 3H), 0.64 (s, 3H). 13C NMR (100 MHz, DMSO-d6):  177.04, 144.04, 122.27, 82.74, 79.54,
71.14, 69.75, 67.63, 67.09, 64.12, 59.43, 57.24, 55.24, 52.62, 47.51, 47.32, 46.51, 45.93, 41.78,
41.40, 38.11, 33.71, 33.22, 32.80, 32.62, 31.43, 30.84, 29.51, 29.27, 29.10, 28.56, 27.53, 27.42,
26.11, 26.03, 24.96, 23.80, 23.51, 23.06, 22.53, 18.51, 17.58, 17.24, 16.74, 14.41. HRMS (ESI,
m/z): [M + H]+ Calcd for C44H76NO8: 746.5565; found: 746.5565.
4.2.23. 28-[10-(1-Deoxynojirimycin)-decyl] maslinic acid ester (4g)
Compound 4g was a white solid prepared from 2g and 1-DNJ by using the same method
established for 4a. Yield 50%, mp: 122 C123 C. 1H NMR (400 MHz, DMSO-d6):  5.17 (s, 1H),
4.704.74 (m, 2H), 4.294.38 (m, 2H), 3.893.96 (m, 2H), 3.673.70 (m, 1H), 3.553.57 (m, 1H),
3.033.05 (m, 1H), 2.902.93 (m, 1H), 2.712.80 (m. 4H), 1.911.97 (m, 1H), 1.811.83 (m, 1H),
1.711.75 (m, 2H), 1.581.65 (m, 4H), 1.501.55 (m, 6H), 1.381.43 (m, 5H), 1.301.32 (m, 4H),

1.23 (s, 8H), 1.151.18 (m, 3H), 1.08 (s, 3H), 0.90 (t, J = 12 Hz, 12H), 0.69 (s, 3H), 0.64 (s, 3H).
13C NMR (100 MHz, DMSO-d6):  177.16, 144.18, 122.39, 82.87, 79.65, 71.25, 69.85, 67.76, 67.18,
64.23, 59.51, 57.31, 55.35, 52.74, 47.63, 47.43, 46.64, 46.06, 41.91, 41.52, 38.23, 33.84, 33.35,
32.92, 32.75, 30.97, 29.67, 29.40, 29.17, 28.69, 27.66, 26.24, 26.17, 25.07, 23.93, 23.64, 23.18,
18.64, 17.71, 17.37, 16.87. HRMS (ESI, m/z): [M + Na]+ Calcd for C46H79NNaO8: 796.5698; found:
796.5699.
4.2.24. 28-[12-(1-Deoxynojirimycin)-dodecyl] maslinic acid ester (4h)
Compound 4h was a white solid prepared from 2h and 1-DNJ by using the same method
established for 4a. Yield 54%, mp: 125 C126 C. 1H NMR (400 MHz, DMSO-d6):  5.17 (s, 1H),
4.654.71 (m, 2H), 4.284.38 (m, 2H), 3.883.95 (m, 2H), 3.683.70 (m, 1H), 3.533.56 (m, 1H),
3.013.06 (m, 1H), 2.882.92 (m, 1H), 2.712.80 (m, 4H), 1.911.97 (m, 2H), 1.811.83 (m, 2H),
1.711.75 (m, 2H), 1.591.65 (m, 3H), 1.491.55 (m, 6H), 1.411.44 (m, 2H), 1.351.38 (m, 3H),
1.291.32 (m, 5H), 1.23 (s, 16H), 1.09 (s, 3H), 0.91 (d, J = 20.0 Hz, 12H), 0.69 (s, 3H), 0.64 (s,
3H). 13C NMR (100 MHz, DMSO-d6):  177.15, 144.18, 122.39, 82.87, 79.70, 71.29, 69.88, 67.76,
67.19, 64.22, 59.54, 57.41, 55.34, 52.73, 47.63, 47.42, 46.64, 46.07, 41.90, 41.52, 38.23, 33.85,
33.36, 32.92, 32.75, 31.56, 30.96, 29.78, 29.72, 29.62, 29.39, 29.16, 28.68, 27.68, 26.23, 26.16,
25.09, 23.92, 23.64, 23.19, 22.66, 18.64, 17.68, 17.37, 16.87, 14.53. HRMS (ESI, m/z): [M + Na]+
Calcd for C48H83NNaO8: 824.6011; found: 824.6011.
4.2.25. 28-[2-(1-Deoxynojirimycin)-ethyl] corosolic acid ester (5a)
Compound 5a was a white solid prepared from 3a and 1-DNJ by using the same method
established for 4a. Yield 43%, mp: 161 C162 C. 1H NMR (400 MHz, DMSO-d6):  5.17 (s, 1H),
4.674.72 (m, 1H), 4.374.38 (m, 1H), 4.214.27 (m, 2H), 4.004.03 (m, 1H), 3.883.91 (m, 1H),

3.753.79 (m, 1H), 3.513.53 (m, 1H), 3.163.18 (m, 1H), 2.892.99 (m, 4H), 2.782.82 (m, 1H),
2.712.74 (m, 1H), 2.092.14 (m, 2H), 2.032.06 (m, 1H), 1.941.97 (m, 1H), 1.851.87 (m, 1H),
1.711.79 (m, 1H), 1.541.57 (m, 2H), 1.431.49 (m, 4H), 1.281.33 (m, 3H), 1.03 (s, 3H), 0.91
(s, 9H), 0.81 (d, J = 4 Hz, 3H), 0.69 (d, J = 12 Hz, 6H). 13C NMR (100 MHz, DMSO-d6):  176.97,
138.51, 125.57, 82.91, 79.73, 71.39, 69.94, 67.78, 67.02, 61.96, 60.07, 58.37, 55.36, 53.01, 50.78,
47.89, 47.68, 47.60, 42.23, 39.08, 38.94, 38.17, 36.79, 33.16, 30.67, 29.43, 28.05, 24.37, 23.97,
23.56, 22.65, 21.57, 18.61, 17.76, 17.55, 17.37, 17.02. HRMS (ESI, m/z): [M + H]+ Calcd for
C38H64NO8: 662.4626; found: 662.4627.
4.2.26. 28-[3-(1-Deoxynojirimycin)-propyl] corosolic acid ester (5b)
Compound 5b was a white solid prepared from 3b and 1-DNJ by using the same method
established for 4a. Yield 42%, mp: 188 C189 C. 1H NMR (400 MHz, DMSO-d6):  5.16 (s, 1H),
4.744.71 (m, 2H), 4.38 (s, 1H), 4,27 (s, 1H), 3.873.93 (m, 2H), 3.71 (d, J = 8 Hz, 1H), 3.51-3.55
(m, 1H), 3.193.22 (m, 1H), 3.003.05 (m, 1H), 2.722.93 (m, 4H), 2.13 (d, J = 8 Hz, 1H),
1.761.96 (m, 6H), 1.231.68 (m, 16H), 1.03 (s, 3H), 0.90 (s, 9H), 0.81 (s, 3H), 0.66 (d, J = 8 Hz,
6H). 13C NMR (100 MHz, DMSO-d6):  175.72, 137.41, 124.25, 81.69, 78.46, 70.90, 68.64, 66.58,
66.14, 61.73, 58.52, 56.22, 54.16, 51.89, 48.21, 46.78, 46.48, 46.40, 41.08, 37.83, 37.76, 36.96,
35.64, 32.02, 29.50, 28.24, 26.84, 23.51, 23.21, 22.71, 22.39, 20.39, 17.41, 16.57, 16.33, 16.22,
15.83. HRMS (ESI, m/z): [M + K]+ Calcd for C39H65NKO8: 714.4342; found: 714.4342.
4.2.27. 28-[4-(1-Deoxynojirimycin)-butyl] corosolic acid ester (5c)
Compound 5c was a white solid prepared from 3c and 1-DNJ by using the same method
established for 4a. Yield 54%, mp: 154 C155 C. 1H NMR (400 MHz, DMSO-d6):  5.15 (s, 1H),
4.724.80 (m, 2H), 4.41 (s, 1H), 4.31 (s, 1H), 3.90 (s, 2H), 3.693.72 (m, 1H), 3.533.57 (m, 1H),

3.203.24 (m, 1H), 3.023.06 (m, 1H), 2.912.94 (m, 1H), 2.722.81 (m, 3H), 2.12 (d, J = 12 Hz,
1H), 1.692.00 (m, 8H), 1.451.57 (m, 13H), 1.301.35 (m, 3H), 1.23 (s, 3H), 0.81 (t, J = 36 Hz,
12H), 0.66 (d, J = 12 Hz, 3H). 13C NMR (100 MHz, DMSO-d6):  176.31, 137.95, 124.84, 82.24,
79.05, 70.52, 69.19, 67.13, 66.58, 63.69, 58.78, 56.59, 54.71, 52.45, 51.62, 47.36, 46.99, 46.96,
41.63, 38.41, 38.32, 37.50, 36.29, 32.59, 30.93, 30.05, 28.81, 27.36, 26.15, 23.76, 23.28, 22.96,
22.04, 20.97, 17.95, 17.16, 16.92, 16.77, 16.40, 13.93. HRMS (ESI, m/z): [M + H]+ Calcd for
C40H68NO8: 690.4939; found: 690.4940.
4.2.28. 28-[5-(1-Deoxynojirimycin)-amyl] corosolic acid ester (5d)
Compound 5d was a white solid prepared from 3d and 1-DNJ by using the same method
established for 4a. Yield 55%, mp: 135 C136 C. 1H NMR (400 MHz, DMSO-d6):  5.15 (s, 1H),
4.714.78 (m, 1H), 4.37 (d, J = 44 Hz, 2H), 3.893.90 (m, 2H), 3.703.72 (m, 1H), 3.553.59 (m,
1H), 3.043.07 (m, 1H), 2.902.95 (m, 1H), 2.722.83 (m, 3H), 2.122.15 (m, 1H), 1.932.00 (m,
2H), 1.86 (s, 2H), 1.761.79 (m, 1H), 1.691.71 (m, 1H), 1.431.53 (m, 12H), 1.221.31 (m, 6H),
1.03 (s, 3H), 0.9 (s, 9H), 0.81 (s, 3H), 0.69 (d, J = 12.0 Hz, 6H). 13C NMR (100 MHz, DMSO-d6):
 176.83, 138.45, 125.34, 82.71, 79.62, 70.97, 69.91, 67.60, 67.07, 64.14, 59.39, 57.08, 55.20, 52.94,
52.45, 47.86, 47.54, 47.41, 42.12, 38.92, 38.30, 38.00, 36.79, 33.08, 30.52, 29.30, 28.46, 27.83,
24.24, 23.98, 23.78, 23.45, 21.47, 18.46, 17.66, 17.42, 17.29, 16.91. HRMS (ESI, m/z): [M + K]+
Calcd for C41H69NKO8: 726.4915; found: 726.4915.
4.2.29. 28-[6-(1-Deoxynojirimycin)-hexyl] corosolic acid ester (5e)
Compound 5e was a white solid prepared from 3e and 1-DNJ by using the same method
established for 4a. Yield 53%, mp: 137 C138 C. 1H NMR (400 MHz, DMSO-d6):  5.15 (s, 1H),
4.694.75 (m, 2H), 4.264.38 (m, 2H), 3.863.91 (m, 2H), 3.683.71 (m, 1H), 3.543.57 (m, 1H),

3.033.07 (m, 1H), 2.882.92 (m, 1H), 2.722.82 (m, 4H), 2.122.15 (m, 1H), 1.951.99 (m, 3H),
1.841.87 (m, 2H), 1.761.80 (m, 2H), 1.691.70 (m, 1H), 1.481.53 (m, 7H), 1.411.45 (m, 3H),
1.281.33 (m, 6H), 1.221.25 (m, 3H), 1.03 (s, 3H), 0.91 (s, 3H), 0.82 (d, J = 8.0 Hz, 3H), 0.69 (d,
J = 12.0 Hz, 6H). 13C NMR (100 MHz, DMSO-d6):  176.95, 138.63, 125.47, 82.89, 79.69, 71.23,
69.85, 67.78, 67.23, 64.25, 59.50, 57.33, 55.37, 53.10, 52.66, 48.02, 47.67, 47.58, 42.29, 39.07,
38.96, 38.16, 36.94, 33.25, 30.68, 29.44, 28.70, 27.99, 27.19, 26.17, 25.00, 24.40, 23.91, 23.59,
21.59, 18.61, 17.77, 17.53, 17.43, 17.03. HRMS (ESI, m/z): [M + H]+ Calcd for C42H72NO8:
718.5252; found: 718.5252.
4.2.30. 28-[8-(1-Deoxynojirimycin)-octyl] corosolic acid ester (5f)
Compound 5f was a white solid prepared from 3f and 1-DNJ by using the same method
established for 4a. Yield 51%, mp: 120 C121 C. 1H NMR (400 MHz, DMSO-d6):  5.10 (s, 1H),
4.634.68 (m, 2H), 4.53 (s, 1H), 4.24 (s, 1H), 4.084.12 (m, 1H), 3.813.88 (m, 2H), 3.64 (d, J =
12 Hz, 1H), 3.483.52 (m, 1H), 3.133.17 (m, 1H), 2.953.01 (m, 1H), 2.842.88 (m, 1H),
2.672.77 (m, 3H), 2.08 (d, J = 12 Hz, 1H), 1.621.96 (m, 8H), 1.371.94 (m, 9H), 1.151.31 (m,
15H). 13C NMR (100 MHz, DMSO-d6):  175.72, 137.42, 124.24, 81.65, 78.43, 69.98, 68.62, 66.54,
65.98, 63.05, 58.20, 56.11, 54.14, 51.87, 51.54, 46.80, 46.44, 46.35, 41.06, 37.87, 37.76, 36.93,
35.73, 32.03, 29.48, 28.44, 28.22, 28.08, 27.47, 26.77, 26.40, 24.98, 23.80, 23.19, 22.71, 22.36,
20.39, 17.40, 16.58, 16.34, 16.20, 15.79. HRMS (ESI, m/z): [M + K]+ Calcd for C44H75NKO8:
784.5124; found: 784.5125.
4.2.31. 28-[10-(1-Deoxynojirimycin)-decyl] corosolic acid ester (5g)
Compound 5g was a white solid prepared from 3g and 1-DNJ by using the same method
established for 4a. Yield 55%, mp: 131 C132 C. 1H NMR (400 MHz, DMSO-d6):  5.14 (s, 1H),

4.674.73 (m, 2H), 4.38 (d, J = 4 Hz, 1H), 4.274.30 (m, 1H), 3.863.91 (m, 2H), 3.673.70 (m,
1H), 3.533.57 (m, 1H), 3.193.22 (m, 1H), 3.013.06 (m, 1H), 2.892.92 (m, 1H), 2.712.81 (m,
3H), 2.12 (d, J = 12 Hz, 1H), 1.831.99 (m, 5H), 1.671.79 (m, 3H), 1.411.56 (m, 11H), 1.291.36
(m, 7H), 1.24 (s, 10H), 1.03 (s, 3H), 0.89 (d, J = 8 Hz, 9H), 0.80 (d, J = 8 Hz, 3H), 0.66 (d, J = 12
Hz, 6H). 13C NMR (100 MHz, DMSO-d6):  175.69, 137.42, 124.24, 81.67, 78.43, 69.99, 68.61,
66.55, 65.94, 63.03, 58.20, 56.11, 54.13, 51.87, 51.54, 46.79, 46.43, 46.35, 41.05, 37.88, 37.76,
36.94, 35.73, 32.03, 30.37, 29.49, 28.51, 28.22, 28.02, 27.47, 26.78, 26.50, 24.99, 23.82, 23.79,
23.19, 22.70, 22.36, 21.48, 20.39, 17.41, 16.56, 16.33, 16.20, 15.79, 13.36. HRMS (ESI, m/z): [M
+ Na]+ Calcd for C46H79NNaO8: 796.5698; found: 796.5699.
4.2.32. 28-[12-(1-Deoxynojirimycin)-dodecyl] corosolic acid ester (5h)
Compound 5h was a white solid prepared from 3h and 1-DNJ by using the same method
established for 4a. Yield 45%, mp: 120 C121 C. 1H NMR (400 MHz, DMSO-d6):  5.14 (s, 1H),
4.714.76 (m, 2H), 4.40 (s, 1H), 4.194.29 (m, 1H), 3.88 (s, 2H), 3.67 (d, J = 12 Hz, 1H), 3.543.57
(m, 1H), 3.193.23 (m, 1H), 3.043.08 (m, 1H), 2.902.93 (m, 1H), 2.712.82 (m, 3H), 2.13 (d, J
= 8 Hz, 1H), 1.671.97 (m, 9H), 1.411.55 (m, 11H), 1.301.36 (m, 7H), 1.23 (s, 13H), 1.03 (s,
3H), 0.90 (s, 9H), 0.81 (s, 3H), 0.66 (d, J = 8 Hz, 6H). 13C NMR (100 MHz, DMSO-d6):  176.24,
137.99, 124.82, 82.26, 78.98, 70.54, 69.14, 67.14, 66.51, 63.59, 58.70, 56.62, 54.70, 52.45, 52.10,
47.37, 46.94, 41.64, 38.46, 38.35, 37.52, 36.31, 32.61, 30.08, 29.10, 29.04, 28.78, 28.57, 28.03,
27.37, 27.05, 25.55, 24.41, 23.78, 23.27, 22.94, 20.94, 17.99, 17.10, 16.88, 16.78, 16.36. HRMS
(ESI, m/z): [M + Na]+ Calcd for C48H83NNaO8: 824.6011; found: 824.6011.
4.3. Synthesis of MA/CA-piperazines derivatives
4.3.1. 2α, 3β-Diacetoxy-ole-12-en-28-oic acid (6)