Design, synthesis and antitumor activity of novel artemisinin derivatives using hybrid approach

Article abstract of DOI:10.1248/cpb.59.984

In an attempt to develop potent and selective anti-tumor agents, two novel series of artemisinin-chalcone hybrids were designed, synthesized and screened for their antitumor activities against HT-29, A549, MDA-MB-231, HeLa and H460 cell lines in vitro. Nearly all of the tested compounds showed significantly increased anti-tumor activity compared with the corresponding dihydroartemisinin (DHA). Most of the title compounds displayed good selectivity toward HT-29 and HeLa cell lines with IC₅₀ values ranging from 0.09 to 0.85μM. Among them, the most promising compound 9c (IC₅₀ range of 0.09-0.93μM) was 10.5- to 70-times more active than DHA (IC₅₀ range of 5.6-15.6μM) respectively.

Full text of DOI:10.1248/cpb.59.984

984
Regular Article
Chem. Pharm. Bull. 59(8) 984—990 (2011)
Vol. 59, No. 8
Design, Synthesis and Antitumor Activity of Novel Artemisinin
Derivatives Using Hybrid Approach
a
a
b
a
a
a
,a
*
Lijun XIE, Xin ZHAI, Lixiang REN, Haiyan MENG, Chun LIU, Wufu ZHU, and Yanfang ZHAO
a Key Laboratory of Original New Drug Design and Discovery of Ministry of Education, Shenyang Pharmaceutical
b
University; 103 Wenhua Road, Shenhe District 110016, P. R. China: and Shenyang J & Health Bio-technic Development
Co., Ltd.; Shenyang 110016, P. R. China. Received March 10, 2011; accepted May 21, 2011; published online May 30, 2011
In an attempt to develop potent and selective anti-tumor agents, two novel series of artemisinin-chalcone hy-
brids were designed, synthesized and screened for their antitumor activities against HT-29, A549, MDA-MB-231,
HeLa and H460 cell lines in vitro. Nearly all of the tested compounds showed significantly increased anti-tumor
activity compared with the corresponding dihydroartemisinin (DHA). Most of the title compounds displayed
good selectivity toward HT-29 and HeLa cell lines with IC50 values ranging from 0.09 to 0.85 mM. Among them,
the most promising compound 9c (IC50 range of 0.09—0.93 mM) was 10.5- to 70-times more active than DHA
(IC50 range of 5.6—15.6 mM) respectively.
Key words artemisinin; chalcone; hybrid approach; anti-tumor activity; X-ray crystallography
Despite cancer chemotherapy has entered a new era of titumor agents, for which several modes of action have been
molecularly targeted therapeutics and some forms of cancer proposed. The key mechanism is the inhibition of tubulin
have been successfully treated by modern therapies, the suc- polymerization, while also including the inhibition of angio-
cessful treatment of cancer remains a significant challenge in genesis and the induction of apoptosis.22—24) Chalcones and
the future because chemotherapy is limited by the drug re- artemisinin analogues represent two classes of natural prod-
sistance and adverse side effects.1) In order to develop more ucts, whose antitumor effects appear to be consistent via dif-
effective and reliable anticancer agents that circumvent these ferent molecular mechanisms. As the application of hybrid
limitations, the search for novel anti-tumor agents has turned strategy to synthesize artemisinin analogues are continuously
to natural products, in particular plants used in traditional emerging,9,25) it is reasonable to combine their structure ana-
folk medicines.2)
logues to form a single molecular framework with a linker,
In recent years, artemisinin and its derivatives have been which would allow us to find more potent anti-tumor agents,
widely studied for their anticancer activities. Some of them in which these ‘merge’ pharmacophore may be addressing
showed excellent anti-tumor activity toward different cancer the active site of different targets and offering the possibility
cell lines in vitro.3—9) Also, several studies demonstrated that to overcome drug resistance. Intrigued by these observations,
artemisinin analogues were effective to many drug- and radi- we designed and synthesized two new series of novel
ation-resistant cancer cell lines due to their multiple mecha- artemisinin derivatives by replacement of oxygen at C-10
nisms.10,11) The main mode likely involves a similar metal- with nitrogen, in which the substituted chalcone group is
induced free-radical formation leading to induce apoptosis bonded to the artemisinin nucleus through an oxyacetyl link-
in cancer cells and inhibit the tumor angiogenesis.12—16)
Recently, considerable attention has been focused on chal-
age.
Chemistry The synthetic routes of compounds are out-
cones, which are a class of privileged structures that are eas- lined in Chart 1. Separable diastereomeric mixture of 10b-
ily prepared and have a wide range of biological proper- azidodihydroartemisinin (2) and 10a-azidodihydroarte-
ties,17—21) which makes them an attractive pharmacophoric misinin (3) were obtained by treating 1 with trimethylsilyl
scaffold. An area of particular interest is their potential as an- chloride, sodium azide and sodium iodide at room tempera-
ture for 28 h, according to ref 6. The a and b isomers ap-
peared as two distinct spots on TLC and were separated by
column chromatography, with b-isomers as the major prod-
ucts. The reduction of azido compounds (2, 3) with
Staudinger reaction afforded the corresponding 10b-amino-
dihydroartemisinin (4) and 10a-aminodihydroartemisinin (5)
respectively, which subsequently reacted with chloroacetyl
chloride to afford two important intermediates 10b-N-
chloroacetyl-aminodihydroartemisinin (7) and 10a-N-
chloroacetyl-amino-dihydroartemisinin (8) as white solid.
On the side chain, the preparation of the chalcone ana-
logues was carried out via Claisen–Schmidt condensation.
This method for the preparation of chalcones is attractive
since it predominantly generates the (E)-isomer from simple
building blocks.26) Coupling constants (Jtransꢀ15—16 Hz)
from the proton nuclear magnetic resonance (1H-NMR) spec-
tra of the title compounds clearly indicated that derivatives
Fig. 1. The Structures of DHA, Chalcone and the Target Compounds
∗ To whom correspondence should be addressed. e-mail: yanfangzhao@126.com
© 2011 Pharmaceutical Society of Japan

August 2011
985
Reagents and conditions: (a) Me3SiCl, NaN3, NaI, dichloromethane, r.t., 28 h; (b) PPh3, H2O, THF, 60 °C, 6 h; (c) 2-chloroacetyl chloride, Et3N, 0—10 °C, 3 h; (d)
compound 6, K2CO3, NaI, DMF, 60 °C, 5 h; (e) KOH, ethanol, r.t., 24 h.
Chart 1
6a—l were both geometrically pure and were exclusively
trans (E) isomers. Thus, appropriate aryl aldehydes were re-
acted with inexpensive p-hydroxyacetophenone in ethanol/
KOH at 0—5 °C. Upon completion, the cooled reaction mix-
ture was poured into ice water and treated with HCl (10%)
yielded the desired chalcone analogues (6a—l).
Finally, the target compounds 9a—l and 10a—l were suc-
cessfully obtained via the reaction of intermediate 7 and 8
with 6a—m in the presence of K2CO3 and sodium iodide in
N,N-dimethylformamide (DMF) at 60 °C, respectively. The
products obtained were purified by column chromatography
on silica gel.
The formation of 10b-azidoartemisinin (2) and 10a-azi-
Fig. 2. ORTEP Diagram Showing the X-Ray Crystal Structure of 5
1
doartemisinin (3) were confirmed by H-NMR spectrum and
LC-MS data. In our previous report, the stereochemistry of
compound 2 had ready been determined by single crystal X-
The formation of two important intermediates (7, 8) were
ray diffraction studies.27) The structure of compound 3 was confirmed by 1H-NMR spectral and LC-MS data, The forma-
elucidated by 1H-NMR spectrum and LC-MS analyses. tion of the title compounds, were evidenced by H-NMR
1
Specifically, the configuration at the C-10 position of com- spectrum, IR, LC-MS and element analysis data, which were
pound 3 was assigned based on the vicinal couplings explained in experimental part.
(Jꢀ10.1 Hz) between protons at positions 10 and 9, indicat-
ing that the relative configuration at the positions 10 and 9 is Results and Discussion
trans.
Biological Evaluation All the compounds 9a—l and
In addition, the molecular structure of the compound 5 10a—l were evaluated for their anti-tumor activities on
was established by single crystal X-ray diffraction studies. human colorectal cancer cell line (HT-29), human non-small-
The ORTEP view of the molecular structure shows the spa- cell lung cancer cell line (A549), human breast cancer cell
tial atomic positions of compound 5, as shown in Fig. 2. The line (MDA-MB-231), human cervical carcinoma cell line
stereochemistry of compound 3 was further determined indi- (HeLa) and human lung cancer cell line (H460) by the 3-
rectly by the crystal data of compound 5, because the config- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide
uration at the C-10 was not changed when compound 3 was (MTT) assay, using DHA as a control. The results expressed
transformed to compound 5 via the Staudinger reduction.
as IC50 were summarized in Table 1, and the IC50 values are

986
Vol. 59, No. 8
Table 1. Anti-tumor Activity of the Compounds against HT-29, A549,
MDA-MB-231, HeLa and H460 Cell Lines in Vitro
compounds attached electron releasing groups (9h, l) with
the exception of 3,4,5-trimethoxy derivative 9b, with IC50
values 0.70—1.9 mM. The fluoro substituent (9a, e) had com-
parable anti-tumor activity with the unsubstituted analogue
9i. Specifically with the mono-halogen substituted deriva-
tives (9e, f), activity increased in the following order: Cl
(9f)ꢁF (9e). Insertion of a second chlorine atom, to yield the
2,6-dichloro derivative 9g, resulted in about a fourfold in-
crease in activity as compared with 9f. Ignoring the deriva-
tive with a 3-MeO (9h) and 3,4-OCH2O- (9l), the greatest
enhancement of activity occurred with the bulkier sub-
stituents, 3-CF3 (9d) and 4-CF3O (9c).
Regarding the anti-tumor activities of 10a—l, bearing a
same molecular structure but only different C-10 stereo-
chemistry, showed few differences in inhibitory effect against
five cell lines as compared with 9a—l. Among them, the 10c,
d and g had the best activities toward the five cell lines,
which further proved that it was beneficial for enhancing
their anti-tumor activities when compounds with bulkier and
EWG group on the phenyl ring. The replacement of phenyl
with hetero-aryl group would result in a decrease of anti-
tumor activity and hence they aren’t ideally suited for further
modifications.
IC50 (mM)a)
Compd.
No.
HT-29b)
A549b) MDA-MB-231b) HeLab) H460b)
9a
9b
9c
9d
9e
9f
9g
9h
9i
0.93
0.24
0.36
0.26
0.70
0.50
0.14
0.72
0.65
2.3
3.2
3.5
0.80
2.0
4.3
2.8
1.2
2.2
2.5
1.1
1.3
1.1
3.3
0.6
0.28
1.2
4.4
3.0
1.3
1.8
2.0
1.8
3.0
7.2
2.8
1.9
2.4
1.2
3.4
3.1
1.1
2.6
1.7
0.64
0.09
0.18
0.77
0.4
0.29
1.8
0.46
3.8
0.93
0.96
0.87
0.79
0.96
5.4
1.3
2.9
1.6
0.47
1.3
1.7
0.76
1.0
1.7
1.5
0.72
1.2
0.92
1.7
9j
9k
9l
16
8.3
23
1.6
1.2
2.6
1.2
0.75
1.7
10a
10b
10c
10d
10e
10f
10g
10h
10i
10j
10k
10l
4
3.8
8.5
0.68
0.89
2.3
2.4
1.6
2.1
1.8
13
29
12
6.1
4
0.70
0.39
0.24
0.76
0.67
0.50
0.67
0.75
1.4
2.1
1.7
3.6
1.2
1.1
0.27
0.10
1.2
0.98
0.73
0.74
0.85
2.2
0.89
4.2
1.5
3.9
6.3
12
4.7
19
1.9
3.3
23
Conclusion
2.6
2.8
4.6
9.8
In summary, two novel series of hybrid artemisinin deriva-
tives conjugated with chalcone moieties were designed and
synthesized based on the hybrid strategy. The structures were
confirmed by elemental analyses, spectrometry and single
crystal X-ray analysis. Through anti-tumor activity screening
against five cell lines (HT-29, A549, MDA-MB-231, HeLa
and H460), on the basis of the above-described results, the
following conclusions could be drawn: (a) most of the pre-
pared compounds displayed the enhanced and selective anti-
tumor activities toward HT-29 and HeLa cell lines as com-
5
DHAc)
5.6
15.6
13
a) IC50: concentration of the compound (mM) producing 50% cell growth inhibition
after 72 h of drug exposure, as determined by the MTT assay. Each experiment was run
at least two times, and the results are presented as average values. b) HT-29, human
colon cancer cell line; A549, human non-small-cell lung adenocarcinoma cell line;
MDA-MB-231, human breast cancer cell line; HeLa, human cervical carcinoma cell
line; H460, human lung cancer cell line. c) Used as a positive control.
the average of at least two independent experiments.
As shown in Table 1, most of the compounds 9a—l and pared with DHA; (b) introduction of bulkier and EWG group
10a—l were 2.6- to 40-fold more active than the correspond- on the phenyl ring is associated with increased anti-tumor ac-
ing dihydroartemisinin (DHA) respectively, suggesting that tivity. When the phenyl rings were attached by 4-CF3O (9c)
the presence of a chalcone moiety enhanced their anti-tumor or 3-CF3 (9d), the effect was more obvious; (c) the hetero-
activities significantly toward all five cancer cell lines. In aryl group at b-position of the enone system may be detri-
general, most of the prepared compounds showed moderate mental for the activity; (d) the configuration of compounds
activity against MDA-MB-231, A549 and H460 cell lines 9a—l, 10a—l at C-10 position has little influence on their
with IC50 values ranging from 0.68 to 29 mM, which were anti-tumor activities. Moreover, the two important intermedi-
several- to tens-fold less potent than against HT-29 and HeLa ates 4 and 5 reported firstly also show more potent anti-
cell lines respectively. The results demonstrated that the in- tumor activities than DHA. Taking them as intermediates,
troduction of a chalcone moiety also enhanced their selectiv- many novel arteminin derivatives will be obtained and evalu-
ity significantly for HT-29 and HeLa cell lines. The two key ated for their biological activities. To assess the potentials of
intermediates 4 and 5 with amino group at C-10 position these new compounds as cancer chemotherapeutic agents,
caused only a minor improvement in anti-tumor activity further in vivo activity and toxicity studies are needed. The
against the five cancer cell lines as compared to DHA.
results obtained from this study can be used as guidelines for
Turning to the effects of 9j and 9k containing heteroaro- further development.
matic chalcone moiety, interestingly, the bioisosteric replace-
ment of phenyl (9i) with a thiophene ring (9k) and furan (9j)
Experimental
Reagents and General Procedures All melting points were obtained
ring decreased activity greatly against the five tumor cell
lines respectively. It may be concluded that the presence of
heteroaromatic ring is detrimental for the activity. The data
in Table 1 demonstrated that substitution pattern on the
phenyl rings linked to the b-position of the enone system af-
fected their potency significantly. For 9a—l, in most cases,
compounds (9c, d, g) bearing electron withdrawing groups
on a Büchi Melting Point B-540 apparatus (Büchi Labortechnik, Flawil,
Switzerland) and were uncorrected. Mass spectra (MS) were taken in elec-
trospray ionization (ESI) mode on Agilent 1100 LC-MS (Agilent, Palo Alto,
CA, U.S.A.). Proton (1H) nuclear magnetic resonance spectroscopy was per-
formed using Bruker ARX-300, 300 MHz spectrometers (Bruker Bio-
science, Billerica, MA, U.S.A.) with tetramethylsilane (TMS) as an internal
standard. IR spectra (KBr disks) were recorded with a Bruker IFS 55 instru-
ment (Bruker). Elemental analysis was determined on a Carlo-Erba 1106 El-
(EWG) at the phenyl rings are found to be more active than emental analysis instrument (Carlo Erba, Milan, Italy). Unless otherwise

August 2011
987
noted, all the materials were obtained from commercially available sources
and were used without further purification.
Table 2. Crystal Data and Measurement Detail for Compound 5
Preparation of 10b-Azidodihydroartemisinin (2), 10a-Azidodihydro-
artemisinin (3) Trimethylchlorosilane (300 mmol, 38.1 ml) was added
gradually to the mixture solution of dihydroartemisinin (200 mmol, 56.8 g)
and sodium azide (300 mmol, 19.5 g) in dry dichloromethane (300 ml), then
sodium iodide (5 mmol, 3.0 g) was added to the reaction mixture at 0—5 °C.
The reaction mixture was stirred at room temperature for 28 h. The mixture
was quenched with a saturated NaHCO3 solution (100 ml) and diluted with
dichloromethane. Two phases were separated and the organic phase was
washed with brine, the organic phase was then collected and dried overnight
over anhydrous Na2SO4. After filtering, the solvent was evaporated under re-
duced pressure. The crude mixture was purified by column chromatography
(silica, 1—5% EtOAc/hexanes) to furnish the compound 2 (29.0 g, 47%) and
compound 3 as white solid (3.0 g, 5%). Compound 2: mp: 41—43 °C; MS
(ESI) m/z: 332.2 (MꢂNa)ꢂ; 1H-NMR (300 MHz, DMSO-d6) d: 5.76 (s, 1H),
5.54 (d, Jꢀ3.6 Hz, 1H), 2.46 (m, 1H), 2.26—2.12 (m, 1H), 2.07—1.96 (m,
1H), 1.87—1.78 (m, 1H), 1.77—1.65 (m, 1H), 1.58 (m,2H), 1.48—1.33 (m,
3H), 1.31 (s, 3H), 1.16 (m, 1H), 0.89 (d, Jꢀ6.3 Hz, 3H), 0.84 (d, Jꢀ7.3 Hz,
Crystal data
Empirical formula
Formula weight
Crystal system
Crystal dimension
Space group
C15H25NO4
283.36
Orthorhombic
0.40 mmꢃ0.45 mmꢃ0.48 mm
P212121 (No. 19)
9.2901(8)
9.3435(9)
17.2037(16)
1493.3(2)
90.00, 90.00, 90.00
4
1.260
616
0.090
a (Å)
b (Å)
c (Å)
Volume (Å3)
Angle a, b, g
Z
Crystal density, g/cm3
F(000)
m(MoKa) [/mm]
Absorption coefficient
Cut-off used in R-factor calculations
R(Fo)
0.090
1
2
2
3H). Compound 3: mp: 101—103 °C; MS (ESI) m/z: 332.2 (MꢂNa)ꢂ; H-
Fo ꢁ2s (Fo )
0.0358
NMR (300 MHz, DMSO-d6) d: 5.53 (s, 1H), 4.86 (d, Jꢀ10.1 Hz, 1H),
2.29—2.06 (m, 2H), 2.05—1.94 (m, 1H), 1.87—1.76 (m, 1H), 1.65—1.33
(m, 5H), 1.30 (s, 3H), 1.24—1.10 (m, 1H), 0.89 (d, Jꢀ6.2 Hz, 3H), 0.81 (d,
Jꢀ7.1 Hz, 3H).
2
Rw (Fo )
0.0902
298
0.71073
Fine-focus sealed tube
MoKa
Graphite
ꢄ9: 11; ꢄ8: 11; ꢄ20: 20
1323
SHELXL97
Temperature (T)
Radiation wavelength
Radiation type
Radiation source
Radiation monochromator
Dataset
Preparation of 10b-Aminodihydroartemisinin (4) A 100 ml round-
bottomed flask was charged with compound 2 (16.0 g, 52 mmol) and tetrahy-
drofuran (THF) (130 ml). To this solution, triphenyl phosphine (20.4 g,
78 mmol) was added slowly, and the reaction mixture was stirred for 2 h at
60 °C. At this time, TLC analysis confirmed that no starting material (com-
pound 2) remained. Distilled water (160 mmol, 3.0 ml) was added, and the
resulting suspension was stirred for 6 h. The mixture was concentrated under
reduced pressure. The crude mixture was purified by flash column chro-
matography (silica, dichloromethane/methanol, 200 : 1) to afford the desired
Reflns (Fo)
Structure refinement
1
compound 4 (9.1 g, 62%) as yellow oil. MS (ESI) m/z: 284.1 (MꢂH)ꢂ; H-
3H), 1.17 (m, 1H), 0.89 (d, Jꢀ6.3 Hz, 3H), 0.72 (d, Jꢀ7.1 Hz, 3H).
Preparation of (10S)-N-Chloroacetyl-aminodihydroartemisinin (8)
NMR (300 MHz, CDCl3) d: 5.34 (s, 1H), 4.21 (d, Jꢀ9.7 Hz, 1H), 2.44—
2.31 (m, 1H), 2.30—2.17 (m, 1H), 2.08—1.94 (m, 4H), 1.94—1.83 (m, 2H), The product was prepared from 4 (3.0 g, 10.6 mmol) in a similar manner as
1.81—1.61 (m, 3H), 1.60—1.46 (m, 2H), 1.44 (s, 3H), 0.97 (d, Jꢀ6.2 Hz,
3H), 0.94 (d, Jꢀ7.2 Hz, 3H).
described for the preparation of compound 7. The resultant solid products
were collected by filtration and recrystallized from methanol to give com-
pound 8 (3.1 g, 81%). mp: 175—177 °C; MS (ESI) m/z: 382.2 (MꢂNa)ꢂ;
1H-NMR (300 MHz, CDCl3) d: 5.45 (s, 1H), 5.36 (t, Jꢀ10.1 Hz, 1H), 4.09
(s, 2H), 2.55—2.41 (m, 1H), 2.41—2.32 (m, 1H), 2.11—2.00 (m, 1H),
1.98—1.86 (m, 1H), 1.85—1.70 (m, 2H), 1.71—1.46 (m, 4H), 1.45 (s, 3H),
1.39—1.24 (m, 2H), 0.99 (d, Jꢀ6.0 Hz, 3H), 0.88 (d, Jꢀ7.2 Hz, 3H).
General Procedure for Preparation of Compounds (6a—l) A stirred
Preparation of 10a-Aminodihydroartemisinin (5) This compound
was prepared according to compound
4 from compound 3 (5.0 g,
16.2 mmol), triphenyl phosphine (6.4 g, 24.5 mmol) and distilled water
(52.0 mmol, 1 ml). Purification of the resulting oil afforded 5 as colorless
1
crystal (3.2 g, 70%); mp: 46 °C; MS (ESI) m/z: 284.1 (MꢂH)ꢂ; H-NMR
(300 MHz, DMSO-d6) d: 5.31 (s, 1H), 4.08 (d, Jꢀ9.6 Hz, 1H), 2.23 (s, 2H,
NH2, D2O-exchangable), 2.21—2.10 (m, 1H), 2.08—1.89 (m, 2H), 1.86— solution of p-hydroxyacetophenone (8.1 g, 0.06 mol) in ethanol (200 ml) was
1.72 (m, 1H), 1.65—1.52 (m, 2H), 1.45—1.29 (m, 4H), 1.26 (s, 3H), 0.89 added to 60% KOH (6.7 g, 0.12 mol) solution at 0 °C, the mixture was
(d, Jꢀ6.3 Hz, 3H), 0.79 (d, Jꢀ7.2 Hz, 3H).
stirred at 0 °C temperature for 1 h. The substituted aryl aldehyde (0.06 mol)
was added to the mixture, and the resulting mixture was stirred at room tem-
perature for 24 h. The aqueous mixture was neutralized by the addition of
aqueous 10% HCl solution. The light yellow solid thus obtained was filtered,
The X-ray crystallographic analysis of 5 was determined on a colorless
plate crystal, with approximate dimensions of 0.40 mmꢃ0.45 mmꢃ0.48
mm, grown from the slow evaporation of a dilute ethanol solution at room
temperature. The crystal structure solution was solved by full matrix least- washed with water and dried. The residue was recrystallized from ethanol to
squares method using SHELXL97. All the atoms were located in different
Fourier maps and refined isotropically, using a riding model and all the pro-
jections were generated using ORTEP. The details of the crystal data and re-
finement are shown in Table 2. Crystallographic data (cif file) for 5 have
been deposited with the Cambridge Crystallographic Data Center, CCDC
No. 796528. Copies of this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, U.K. (fax: ꢂ44
1233 336033; e-mail: deposit@ccdc.cam.ac.uk or www:http://www.ccdc.
cam.ac.uk).
afford pure compounds (6a—l).
General Procedure for Preparation of Compounds (9a—l), Com-
pounds (10a—l) K2CO3 (0.12 g, 0.84 mmol) and NaI (0.03 g) were added
to a stirred solution of compound 7 or compound 8 (0.2 g, 0.57 mmol) and
substituted chalcone (0.57 mmol) in DMF (6.0 ml). The reaction mixture
was heated to 60 °C for 3—5 h. The mixture was poured into ice water,
stirred for 1h and separated by filtration to give crude compounds, which pu-
rified by chromatography on silica gel using (1—5% petroleum ether/ethyl
acetate) to obtain 9a—l, 10a—l.
Preparation of (10R)-N-Chloroacetyl-aminodihydroartemisinin (7)
Triethylamine (3.2 g, 31.8 mmol) was added to a solution of compound 4
(6.0 g, 21.2 mmol) in dichloromethane (80 ml) and then 2-chloroacetyl chlo-
ride (3.1 g, 27.6 mmol) was added drop-wise to the reaction mixture at 0—
10 °C. The reaction mixture was stirred at room temperature for 1—3 h.
After completion of reaction as indicated by TLC, the mixture was quenched
with H2O (5 ml) and diluted with dichloromethane (50 ml). The organic
layer was washed with brine (200 ml), dried over MgSO4, filtered, and con-
centrated under reduced pressure. The resultant solid products were col-
(10R)-N-{4-[3-(2,4-Difluorophenyl)-2-(E)-propenoyl]phenyloxyacetyl}-
aminodihydroartemisinin (9a): This compound was obtained as brown solid
in 81% yield. mp: 102—104 °C; MS (ESI) m/z: 606.3 (MꢂNa)ꢂ; IR (KBr)
cmꢄ1: 3421.9, 2926.6, 2873.8, 1690.1, 1664.2, 1606.0, 1503.1, 1274.8,
1216.9, 1173.0, 1038.2, 846.0, 750.9, 612.2. 489.8; 1H-NMR (300 MHz,
CDCl3) d: 8.08 (d, Jꢀ8.9 Hz, 2H), 7.86 (d, Jꢀ15.9 Hz, 1H), 7.66 (dd,
Jꢀ14.9, 8.5 Hz, 1H), 7.60 (d, Jꢀ15.9 Hz, 1H), 7.07 (d, Jꢀ9.0 Hz, 2H),
7.01—6.86 (m, 2H), 5.52—5.40 (m, 2H), 4.62 (s, 2H), 2.51—2.32 (m, 2H),
2.12—2.00 (m, 1H), 1.99—1.86 (m, 1H), 1.84—1.71 (m, 2H), 1.45 (s, 3H),
lected by filtration and recrystallized from methanol to give compound 7 0.99 (d, Jꢀ6.0 Hz, 3H), 0.82 (d, Jꢀ7.2 Hz, 3H); Anal. Calcd for
1
(5.9 g, 78%). mp: 171—173 °C; MS (ESI) m/z: 382.1 (MꢂNa)ꢂ; H-NMR C32H35F2NO7 (in %): C, 65.85; H, 6.04; N, 2.40; Found C, 65.76; H, 6.16
(300 MHz, DMSO-d6) d: 8.96 (d, Jꢀ9.1 Hz, 1H), 5.47 (s, 1H), 5.08 (t,
Jꢀ9.8 Hz, 1H), 4.09 (s, 2H), 2.40—2.25 (m, 1H), 2.18 (td, Jꢀ14.0, 3.7 Hz,
and N, 2.29.
(10R)-N-{4-[3-(3,4,5-Trimethoxyphenyl)-2-(E)-propenoyl]phenyloxy-
1H), 2.04—1.93 (m, 1H), 1.87—1.75 (m, 1H), 1.66—1.30 (m, 7H), 1.27 (s, acetyl}aminodihydroartemisinin (9b): This compound was obtained as yel-

988
Vol. 59, No. 8
low solid in 76% yield. mp: 115—117 °C; MS (ESI) m/z: 660.5 (MꢂNa)ꢂ; d: 8.94 (d, Jꢀ9.2 Hz, 1H), 8.18 (d, Jꢀ8.8 Hz, 2H), 7.96 (d, Jꢀ15.6 Hz, 1H),
IR (KBr) cmꢄ1: 3422.8, 2937.9, 2874.2, 1691.8, 1659.7, 1603.3, 1579.5,
1504.9, 1281.6, 1127.5, 1038.5, 824.8, 749.4, 596.3; H-NMR (300 MHz,
7.68 (d, Jꢀ15.6 Hz, 1H), 7.48 (s, 1H),7.46—7.33 (m, 2H), 7.11 (d,
Jꢀ8.8 Hz, 2H), 7.08—6.97 (m, 1H), 5.47 (s, 1H), 5.17 (t, Jꢀ9.8 Hz, 1H),
1
DMSO-d6) d: 8.94 (d, Jꢀ9.3 Hz, 1H), 8.18 (d, Jꢀ8.7 Hz, 2H), 7.90 (d, 4.72 (s, 2H), 3.83 (s, 1H), 2.47—2.38 (m, 1H), 2.19 (td, Jꢀ13.7, 3.0 Hz,
Jꢀ15.2 Hz, 1H), 7.67 (d, Jꢀ15.3 Hz, 1H), 7.23 (s, 2H), 7.11 (d, Jꢀ8.8 Hz, 1H), 2.05—1.93 (m, 1H), 1.87—1.74 (m, 1H), 1.28 (s, 3H), 0.89 (d,
2H), 5.47 (s, 1H), 5.17 (t, Jꢀ9.7 Hz, 1H), 4.72 (s, 2H), 3.87 (s, 6H), 3.71 (s, Jꢀ6.2 Hz, 3H), 0.71 (d, Jꢀ7.0 Hz, 3H); Anal. Calcd for C33H39NO8 (in %):
3H), 2.46—2.33 (m, 1H), 2.26—2.11 (m, 1H), 2.05—1.93 (m, 1H), 1.89— C, 68.61; H, 6.80; N, 2.42; Found C, 68.62; H, 6.83 and N, 2.41.
1.73 (m, 1H), 1.28 (s, 3H), 0.89 (d, Jꢀ6.1 Hz, 3H), 0.71 (d, Jꢀ7.0 Hz, 3H);
Anal. Calcd for C35H43NO10 (in %): C, 65.92; H, 6.80; N, 2.20; Found C,
65.84; H, 6.86 and N, 2.19.
(10R)-N-{4-[3-Phenyl-2-(E)-propenoyl]phenyloxyacetyl}aminodihy-
droartemisinin (9i): This compound was obtained as pale yellow solid in
88% yield. mp: 102—104 °C; MS (ESI) m/z: 570.2 (MꢂNa)ꢂ; IR (KBr)
cmꢄ1: 3419.7, 2925.6, 2872.5, 1685.9, 1659.4, 1604.5, 1531.2, 1507.9,
1217.8, 1171.8, 1037.3, 878.1, 841.0, 767.1; 1H-NMR (300 MHz, CDCl3) d:
8.08 (d, Jꢀ8.6 Hz, 2H), 7.83 (d, Jꢀ15.8 Hz, 1H), 7.66 (d, Jꢀ3.4 Hz, 2H),
(10R)-N-{4-[3-(4-Trifluoromethoxyphenyl)-2-(E)-propenoyl]phenyloxy-
acetyl}aminodihydroartemisinin (9c): This compound was obtained as pale
yellow solid in 84% yield. mp: 103—105 °C; MS (ESI) m/z: 654.4
(MꢂNa)ꢂ; IR (KBr) cmꢄ1: 3243.4, 2928.0, 2874.8, 1684.5, 1663.8, 1605.3, 7.55 (d, Jꢀ15.7 Hz, 1H), 7.44 (d, Jꢀ3.3 Hz, 2H), 7.18—7.00 (m, 3H), 5.46
1507.4, 1257.8, 1217.0, 1170.2, 1038.3, 878.3, 828.4, 595.7; 1H-NMR
(300 MHz, DMSO-d6) d: 8.94 (d, Jꢀ9.1 Hz, 1H), 8.18 (d, Jꢀ8.9 Hz, 2H),
8.04 (d, Jꢀ8.8 Hz, 2H), 7.99 (d, Jꢀ15.7 Hz, 1H), 7.73 (d, Jꢀ15.6 Hz, 1H),
7.45 (d, Jꢀ8.6 Hz, 2H), 7.11 (d, Jꢀ8.9 Hz, 2H), 5.47 (s, 1H), 5.17 (t,
Jꢀ9.8 Hz, 1H), 4.72 (s, 2H), 2.46—2.34 (m, 1H), 2.19 (td, Jꢀ14.2, 3.6 Hz,
(t, Jꢀ10.0 Hz, 2H), 4.61 (s, 2H), 2.54—2.31 (m, 2H), 2.11—2.00 (m, 1H),
1.97—1.86 (m, 1H), 1.44 (s, 3H), 0.99 (d, Jꢀ5.7 Hz, 3H), 0.81 (d,
Jꢀ7.2 Hz, 3H); Anal. Calcd for C32H37NO7 (in %): C, 70.18; H, 6.81; N,
2.56; Found C, 70.09; H, 6.88 and N, 2.56.
(10R)-N-{4-[3-(2-Furyl)-2-(E)-propenoyl]phenyloxyacetyl}aminodihy-
1H), 2.06—1.93 (m, 1H), 1.89—1.73 (m, 1H), 1.28 (s, 3H), 0.89 (d, droartemisinin (9j): This compound was obtained as yellow solid in 70%
Jꢀ6.2 Hz, 3H), 0.71 (d, Jꢀ7.1 Hz, 3H); Anal. Calcd for C33H36F3NO8 (in
%): C, 62.75; H, 5.74; N, 2.22; Found C, 62.72; H, 5.78 and N, 2.20.
(10R)-N-{4-[3-(3-Trifluoromethylphenyl)-2-(E)-propenoyl]phenyloxy-
acetyl}aminodihydroartemisinin (9d): This compound was obtained as pale
yield. mp: 115—117 °C; MS (ESI) m/z: 560.1 (MꢂNa)ꢂ; IR (KBr) cmꢄ1
:
3422.1, 2925.6, 2872.8, 1657.4, 1603.8, 1544.3, 1508.0, 1225.8, 1172.8,
1038.4, 1017.7, 880.0, 826.0, 595.5; 1H-NMR (300 MHz, DMSO-d6) d: 8.93
(d, Jꢀ9.1 Hz, 1H), 8.08 (d, Jꢀ8.9 Hz, 2H), 7.90 (d, Jꢀ1.4 Hz, 1H), 7.58 (d,
yellow solid in 82% yield. mp: 113—115 °C; MS (ESI) m/z: 638.7 Jꢀ15.9 Hz, 1H), 7.52 (d, Jꢀ15.8 Hz, 1H), 7.10 (d, Jꢀ2.9 Hz, 1H), 7.08 (d,
(MꢂNa)ꢂ; IR (KBr) cmꢄ1: 3243.8, 2927.5, 2874.3, 2826.3, 1664.4, 1603.5, Jꢀ2.2 Hz, 2H), 6.69 (dd, Jꢀ3.4, 1.8 Hz, 1H), 5.47 (s, 1H), 5.16 (t,
1336.1, 1217.3, 1169.7, 1127.3, 1038.3, 878.4, 801.7, 571.3; 1H-NMR Jꢀ9.8 Hz, 1H), 4.70 (s, 2H), 2.48—2.36 (m, 1H), 2.19 (td, Jꢀ13.9, 3.7 Hz,
(300 MHz, DMSO-d6) d: 8.94 (d, Jꢀ9.1 Hz, 1H), 8.34 (s, 1H), 8.22 (d, 1H), 2.04—1.94 (m, 1H), 1.87—1.74 (m, 1H), 1.28 (s, 3H), 0.89 (d,
Jꢀ8.8 Hz, 2H), 8.13 (d, Jꢀ16.1 Hz, 1H), 7.84—7.74 (m, 3H), 7.69 (t, Jꢀ6.2 Hz, 3H), 0.71 (d, Jꢀ7.1 Hz, 3H); Anal. Calcd for C30H35NO8 (in %):
Jꢀ7.7 Hz, 1H), 7.12 (d, Jꢀ8.8 Hz, 2H), 5.47 (s, 1H), 5.17 (t, Jꢀ9.8 Hz, 1H), C, 67.02; H, 6.56; N, 2.61; Found C, 66.95; H, 6.67 and N, 2.56.
4.72 (s, 2H), 2.44—2.34 (m, 1H), 2.19 (td, Jꢀ14.9, 4.9 Hz, 1H), 2.05—1.94
(m, 1H), 1.86—1.76 (m, 1H), 1.28 (s, 3H), 0.89 (d, Jꢀ6.0 Hz, 3H), 0.71 (d,
Jꢀ7.0 Hz, 3H); Anal. Calcd for C33H36F3NO7 (in %): C, 64.38; H, 5.89; N,
2.28; Found C, 64.35; H, 6.01 and N, 2.29.
(10R)-N-{4-[3-(2-Thienyl)-2-(E)-propenoyl]phenyloxyacetyl}aminodihy-
droartemisinin (9k): This compound was obtained as pale yellow solid in
73% yield. mp: 101—103 °C; MS (ESI) m/z: 576.5 (MꢂNa)ꢂ; IR (KBr)
cmꢄ1: 3419.0, 2924.9, 2872.4, 1686.3, 1654.6, 1601.9, 1535.1, 1506.9,
1236.8, 1214.2, 1172.1, 1037.6, 825.0, 747.5; H-NMR (300 MHz, CDCl3)
d: 8.07 (d, Jꢀ8.8 Hz, 2H), 7.96 (d, Jꢀ15.3 Hz, 1H), 7.46—7.31 (m, 3H),
1
(10R)-N-{4-[3-(4-Fluorophenyl)-2-(E)-propenoyl]phenyloxyacetyl}amino-
dihydroartemisinin (9e): This compound was obtained as pale yellow solid
in 86% yield. mp: 106—108 °C; MS (ESI) m/z: 588.6(MꢂNa)ꢂ; IR (KBr) 7.14—7.09 (m, 1H), 7.06 (d, Jꢀ8.8 Hz, 2H), 5.51—5.40 (m, 1H), 4.62 (s,
cmꢄ1: 3241.4, 2926.4, 2873.3, 1685.4, 1662.4, 1599.3, 1535.3, 1507.7,
1H), 2.53—2.31 (m, 2H), 2.11—2.01 (m, 1H), 1.97—1.87 (m, 1H), 1.84—
1.71 (m, 1H), 1.45 (s, 3H), 0.99 (d, Jꢀ5.9 Hz, 3H), 0.82 (d, Jꢀ7.2 Hz, 3H);
1
1218.9, 1172.9, 1038.3, 845.0, 826.3, 514.4; H-NMR (300 MHz, DMSO-
d6) d: 8.94 (d, Jꢀ9.2 Hz, 1H), 8.18 (d, Jꢀ8.8 Hz, 2H), 7.96 (d, Jꢀ15.6 Hz, Anal. Calcd for C30H35NO7S (in %): C, 65.08; H, 6.37; N, 2.53; Found C,
1H), 7.68 (d, Jꢀ15.6 Hz, 1H), 7.48 (s, 1H),7.46—7.33 (m, 2H), 7.11 (d, 65.02; H, 6.45 and N, 2.47.
Jꢀ8.8 Hz, 2H), 7.08—6.97 (m, 1H), 5.47 (s, 1H), 5.17 (t, Jꢀ9.8 Hz, 1H),
(10R)-N-{4-[3-(1,3-Benzodioxo-5-yl)-2-(E)-propenoyl]phenyloxyacetyl}-
4.72 (s, 2H), 3.83 (s, 1H), 2.47—2.38 (m, 1H), 2.19 (td, Jꢀ13.7, 3.0 Hz, aminodihydroartemisinin (9l): This compound was obtained as pale yellow
1H), 2.05—1.93 (m, 1H), 1.87—1.74 (m, 1H), 1.28 (s, 3H), 0.89 (d, solid in 78% yield. mp: 110—112 °C; MS (ESI) m/z: 614.6 (MꢂNa)ꢂ; IR
Jꢀ6.2 Hz, 3H), 0.71 (d, Jꢀ7.0 Hz, 3H); Anal. Calcd for C32H36FNO7 (in %):
C, 67.95; H, 6.42; N, 2.48; Found C, 67.96; H, 6.49 and N, 2.42.
(KBr) cmꢄ1: 3421.3, 2936.1, 2883.2, 1680.1, 1655.2, 1606.1, 1513.2,
1254.7, 1216.8, 1153.0, 1108.2, 847.2, 750.6, 623.6. 483.8; 1H-NMR
(300 MHz, DMSO-d6) d: 8.93 (d, Jꢀ9.2 Hz, 1H), 8.16 (d, Jꢀ8.7 Hz, 2H),
7.83 (d, Jꢀ15.4 Hz, 1H), 7.69—7.59(m, 2H), 7.32 (d, Jꢀ7.9 Hz, 1H), 7.09
(d, Jꢀ8.8 Hz, 2H), 6.99 (d, Jꢀ8.0 Hz, 1H), 6.11 (s, 2H), 5.47 (s, 1H), 5.17
(t, Jꢀ9.8 Hz, 1H), 4.71 (s, 2H), 2.47—2.36 (m, 1H), 2.26—2.12 (m, 1H),
2.05—1.94 (m, 1H), 1.86—1.74 (m, 1H), 1.28 (s, 3H), 0.89 (d, Jꢀ6.2 Hz,
(10R)-N-{4-[3-(4-Chlorophenyl)-2-(E)-propenoyl]phenyloxyacetyl}amino-
dihydroartemisinin (9f): This compound was obtained as pale yellow solid in
82% yield. mp: 108—110 °C; MS (ESI) m/z: 604.2 (MꢂNa)ꢂ; IR (KBr)
cmꢄ1: 3241.7, 2935.9, 2874.8, 1691.8, 1662.6, 1602.5, 1274.2, 1218.8,
1
1173.5, 1068.1, 1038.3, 841.0, 757.6, 515.9; H-NMR (300 MHz, DMSO-
d6) d: 8.93 (d, Jꢀ8.8 Hz, 1H), 8.18 (d, Jꢀ8.6 Hz, 2H), 8.06—7.87 (m, 3H), 3H), 0.71 (d, Jꢀ7.1 Hz, 3H); Anal. Calcd for C33H37NO9 (in %): C, 66.99;
7.70 (d, Jꢀ15.7 Hz, 1H), 7.53 (d, Jꢀ8.2 Hz, 2H), 7.11 (d, Jꢀ8.7 Hz, 2H), H, 6.30; N, 2.37; Found C, 66.97; H, 6.37 and N, 2.34.
5.47 (s, 1H), 5.17 (t, Jꢀ9.7 Hz, 1H), 4.72 (s, 2H), 2.46—2.34 (m, 1H),
(10S)-N-{4-[3-(2,4-Difluorophenyl)-2-(E)-propenoyl]phenyloxyacetyl}-
2.29—2.11 (m, 1H), 2.06—1.93 (m, 1H), 1.86—1.75 (m, 1H), 1.28 (s, 3H), aminodihydroartemisinin (10a): This compound was obtained as brown
0.89 (d, Jꢀ5.9 Hz, 3H), 0.71 (d, Jꢀ7.0 Hz, 3H); Anal. Calcd for
powder in 76% yield. mp: 111—113 °C; MS (ESI) m/z: 606.2 (MꢂNa)ꢂ; IR
C32H36ClNO7 (in %): C, 66.03; H, 6.23; N, 2.41; Found C, 66.00; H, 6.36 (KBr) cmꢄ1: 3416.7, 2927.4, 2874.4, 1664.5, 1606.4, 1534.5, 1503.0,
1
and N, 2.37.
1338.2, 1216.7, 1172.8, 1101.6, 966.4, 845.6, 464.8; H-NMR (300 MHz,
CDCl3) d: 8.08 (d, Jꢀ8.9 Hz, 2H), 7.86 (d, Jꢀ15.8 Hz, 1H), 7.66 (dd,
Jꢀ14.9, 8.3 Hz, 1H), 7.60 (d, Jꢀ15.9 Hz, 1H), 7.07 (d, Jꢀ8.9 Hz, 2H),
(10R)-N-{4-[3-(2,6-Dichlorophenyl)-2-(E)-propenoyl]phenyloxyacetyl}-
aminodihydroartemisinin (9g): This compound was obtained as yellow solid
in 83% yield. mp: 103—105 °C; MS (ESI) m/z: 638.2 (MꢂNa)ꢂ; IR (KBr) 7.01—6.87 (m, 2H), 5.53—5.40 (m, 2H), 4.62 (s, 2H), 2.54—2.31 (m, 2H),
cmꢄ1: 3420.6, 2925.9, 2872.8, 1665.8, 1599.5, 1532.5, 1508.4, 1428.4,
2.12—1.99 (m, 1H), 1.98—1.86 (m, 1H), 1.84—1.71 (m, 2H), 1.45 (s, 3H),
1
1256.8, 1220.4, 1171.9, 1038.5, 776.4, 596.3; H-NMR (300 MHz, CDCl3) 0.99 (d, Jꢀ5.9 Hz, 3H), 0.81 (d, Jꢀ7.1 Hz, 3H); Anal. Calcd for
d: 8.08 (d, Jꢀ8.9 Hz, 2H), 7.87 (d, Jꢀ16.1 Hz, 1H), 7.68 (d, Jꢀ16.1 Hz, C32H35F2NO7 (in %): C, 65.85; H, 6.04; N, 2.40; Found C, 65.76; H, 6.15
1H), 7.41 (d, Jꢀ8.0 Hz, 2H), 7.27—7.19 (m, 1H), 7.07 (d, Jꢀ8.9 Hz, 2H), and N, 2.36.
5.51—5.40 (m, 2H), 4.61 (s, 2H), 2.53—2.32 (m, 2H), 2.11—2.00 (m, 1H),
(10S)-N-{4-[3-(3,4,5-Trimethoxyphenyl)-2-(E)-propenoyl]phenyloxy-
1.97—1.87 (m, 1H), 1.83—1.72 (m, 2H), 1.44 (s, 3H), 0.99 (d, Jꢀ6.0 Hz, acetyl}aminodihydroartemisinin (10b): This compound was obtained as pale
3H), 0.81 (d, Jꢀ7.2 Hz, 3H); Anal. Calcd for C32H35Cl2NO7 (in %): C,
62.34; H, 5.72; N, 2.27; Found C, 62.33; H, 5.79 and N, 2.21.
yellow solid in 81% yield. mp: 113—115 °C; MS (ESI) m/z: 660.4
(MꢂNa)ꢂ; IR (KBr) cmꢄ1: 3421.2, 2926.1, 1655.3, 1602.3, 1533.8, 1506.7,
1469.9, 1427.3, 1235.3, 1171.8, 1103.8, 1037.8, 927.1, 806.9, 596.7. 1H-
NMR (300 MHz, CDCl3) d: 8.08 (d, Jꢀ8.8 Hz, 2H), 7.74 (d, Jꢀ15.6 Hz,
(10R)-N-{4-[3-(3-Methoxyphenyl)-2-(E)-propenoyl]phenyloxyacetyl}-
aminodihydroartemisinin (9h): This compound was obtained as white solid
in 87% yield. mp: 110—112 °C; MS (ESI) m/z: 600.4 (MꢂNa)ꢂ; IR (KBr) 1H), 7.42 (d, Jꢀ15.6 Hz, 1H), 7.07 (d, Jꢀ8.7 Hz, 2H), 6.89 (s, 1H), 6.72 (s,
cmꢄ1: 3423.8, 2926.7, 2873.0, 1684.6, 1657.2, 1603.7, 1254.5, 1172.3, 1H), 4.62 (s, 2H), 3.95 (s, 6H), 3.76 (s, 3H), 2.54—2.30 (m, 2H), 2.13—
1
1038.8, 878.1, 835.6, 784.6, 673.6, 574.3; H-NMR (300 MHz, DMSO-d6) 2.00 (m, 1H), 2.00—1.86 (m, 1H), 1.84—1.70 (m, 2H), 1.45 (s, 3H), 0.99

August 2011
989
1
1172.1, 1138.9, 1038.5, 816.9, 472.5; H-NMR (300 MHz, CDCl3) d: 8.08
(d, Jꢀ8.9 Hz, 2H), 7.78 (d, Jꢀ15.6 Hz, 1H), 7.60 (d, Jꢀ8.5 Hz, 2H), 7.52 (d,
Jꢀ15.7 Hz, 1H), 7.41 (d, Jꢀ8.5 Hz, 2H), 7.13—7.02(m, 3H), 5.52—5.41
(m, 2H), 4.62 (s, 2H), 2.54—2.30 (m, 2H), 2.12—1.99 (m, 1H), 1.97—1.86
(m, 1H), 1.85—1.71 (m, 2H), 1.45 (s, 3H), 0.99 (d, Jꢀ5.9 Hz, 3H), 0.82 (d,
Jꢀ7.2 Hz, 3H); Anal. Calcd for C32H37NO7 (in %): C, 70.18; H, 6.81; N,
2.56; Found C, 70.18; H, 6.89 and N, 2.53.
(d, Jꢀ5.6 Hz, 3H), 0.82 (d, Jꢀ7.1 Hz, 3H); Anal. Calcd for C35H43NO10 (in
%): C, 65.92; H, 6.80; N, 2.20; Found C, 65.87; H, 6.84 and N, 2.16.
(10S)-N-{4-[3-(4-Trifluoromethoxyphenyl)-2-(E)-propenoyl]phenyloxy-
acetyl}aminodihydroartemisinin (10c): This compound was obtained as pale
yellow solid in 89% yield. mp: 101—103 °C; MS (ESI) m/z: 654.3
(MꢂNa)ꢂ; IR (KBr) cmꢄ1: 3423.5, 2927.7, 2874.5, 1663.4, 1601.8, 1531.2,
1
1506.5, 1258.4, 1217.5, 1168.7, 1038.5, 828.0, 594.2; H-NMR (300 MHz,
(10S)-N-{4-[3-(2-Furyl)-2-(E)-propenoyl]phenyloxyacetyl}aminodihy-
droartemisinin (10j): This compound was obtained as brown solid in 76%
CDCl3) d: 8.08 (d, Jꢀ8.8 Hz, 2H), 7.99 (d, Jꢀ8.7 Hz, 2H), 7.80 (d,
Jꢀ15.6 Hz, 1H), 7.52 (d, Jꢀ15.7 Hz, 1H), 7.46 (d, Jꢀ8.7 Hz, 2H), 7.07 (d,
Jꢀ8.8 Hz, 2H), 5.53—5.39 (m, 2H), 4.62 (s, 2H), 2.52—2.31 (m, 2H),
2.11—2.00 (m, 1H), 1.98—1.85 (m, 1H), 1.85—1.70 (m, 2H), 1.44 (s, 3H),
0.99 (d, Jꢀ5.8 Hz, 3H), 0.81 (d, Jꢀ8.4 Hz, 3H); Anal. Calcd for
C33H36F3NO8 (in %): C, 62.75; H, 5.74; N, 2.22; Found C, 62.71; H, 5.83
and N, 2.21.
yield. mp: 110—112 °C; MS (ESI) m/z: 560.2 (MꢂNa)ꢂ; IR (KBr) cmꢄ1
:
3421.5, 2925.8, 2873.2, 1685.9, 1659.3, 1603.5, 1550.2, 1258.0, 1225.7,
1
1172.7, 1038.5, 1017.7, 880.0, 595.7; H-NMR (300 MHz, CDCl3) d: 8.09
(d, Jꢀ8.9 Hz, 2H), 7.62 (d, Jꢀ15.3 Hz, 1H), 7.55 (d, Jꢀ1.6 Hz, 1H), 7.47 (d,
Jꢀ15.3 Hz, 1H), 7.06 (d, Jꢀ8.9 Hz, 2H), 6.74 (d, Jꢀ3.4 Hz, 1H), 6.54 (dd,
Jꢀ3.4, 1.8 Hz, 1H), 5.52—5.41 (m, 2H), 4.62 (s, 2H), 2.53—2.31 (m, 2H),
2.12—2.00 (m, 1H), 1.99—1.86 (m, 1H), 1.85—1.71 (m, 2H), 1.45 (s, 3H),
1.36—1.24 (m, 1H), 0.99 (d, Jꢀ6.0 Hz, 3H), 0.81 (d, Jꢀ7.2 Hz, 3H); Anal.
Calcd for C30H35NO8 (in %): C, 67.02; H, 6.56; N, 2.61; Found C, 67.01; H,
6.68 and N, 2.53.
(10S)-N-{4-[3-(3-Trifluoromethylphenyl)-2-(E)-propenoyl]phenyloxy-
acetyl}aminodihydroartemisinin (10d): This compound was obtained as
white solid in 85% yield. mp: 105—107 °C; MS (ESI) m/z: 638.1 (MꢂNa)ꢂ;
IR (KBr) cmꢄ1: 3423.3, 2927.6, 2874.6, 1664.3, 1602.6, 1531.4, 1438.2,
1
1335.9, 1217.5, 1169.6, 1127.2, 1038.3, 801.7, 571.3; H-NMR (300 MHz,
(10S)-N-{4-[3-(2-Thienyl)-2-(E)-propenoyl]phenyloxyacetyl}aminodihy-
droartemisinin (10k): This compound was obtained as pale yellow solid in
71% yield. mp: 117—119 °C; MS (ESI) m/z: 576.1 (MꢂNa)ꢂ; IR (KBr)
cmꢄ1: 3421.3, 2924.5, 2870.6, 1662.3, 1601.6, 1521.5, 1438.2, 1325.9,
CDCl3) d: 8.10 (d, Jꢀ8.8 Hz, 2H), 7.91 (s, 1H), 7.84 (d, Jꢀ15.7 Hz, 1H),
7.72—7.52 (m, 4H), 7.08 (d, Jꢀ8.8 Hz, 2H), 5.53—5.41 (m, 2H), 4.62 (s,
1H), 2.54—2.31 (m, 2H), 2.12—2.01 (m, 1H), 1.99—1.86 (m, 1H), 1.84—
1.72(m, 2H), 1.45 (s, 3H), 0.99 (d, Jꢀ5.9 Hz, 3H), 0.82 (d, Jꢀ7.2 Hz, 3H);
Anal. Calcd for C33H36F3NO7 (in %): C, 64.38; H, 5.89; N, 2.28; Found C,
64.34; H, 5.99 and 2.23.
1
1212.5, 1169.6, 1137.1, 1038.6, 801.7, 561.3; H-NMR (300 MHz, CDCl3)
d: 8.06 (d, Jꢀ8.8 Hz, 2H), 7.96 (d, Jꢀ15.3 Hz, 1H), 7.44 (d, Jꢀ5.0 Hz, 1H),
7.38 (d, Jꢀ3.9 Hz, 1H), 7.35 (d, Jꢀ15.3 Hz, 1H), 7.16—7.09 (m, 1H), 7.06
(d, Jꢀ8.8 Hz, 2H), 5.53—5.41 (m, 2H), 4.61 (s, 2H), 2.53—2.31 (m, 2H),
2.11—2.00 (m, 1H), 1.98—1.86 (m, 1H), 1.83—1.72 (m, 2H), 1.44 (s, 3H),
0.99 (d, Jꢀ5.9 Hz, 3H), 0.81 (d, Jꢀ7.1 Hz, 3H); Anal. Calcd for
C30H35NO7S (in %): C, 65.08; H, 6.37; N, 2.53; Found C, 65.01; H, 6.42 and
N, 2.50.
(10S)-N-{4-[3-(4-Fluorophenyl)-2-(E)-propenoyl]phenyloxyacetyl}amino-
dihydroartemisinin (10e): This compound was obtained as pale yellow solid
in 86% yield. mp: 111—113 °C; MS (ESI) m/z: 588.2 (MꢂNa)ꢂ; IR (KBr)
cmꢄ1: 3424.1, 2927.3, 1662.3, 1599.7, 1536.8, 1507.3, 1418.4, 1382.7,
1
1219.3, 1173.1, 1115.1, 1038.3, 826.9, 515.0; H-NMR (300 MHz, CDCl3)
d: 8.08 (d, Jꢀ8.8 Hz, 2H), 7.80 (d, Jꢀ15.7 Hz, 1H), 7.66 (dd, Jꢀ8.7, 5.4 Hz,
2H), 7.48 (d, Jꢀ15.6 Hz, 1H), 7.17—7.06 (m, 2H), 7.07 (d, Jꢀ8.8 Hz, 2H),
5.53—5.41 (m, 2H), 4.62 (s, 2H), 2.53—2.31 (m, 2H), 2.12—2.00 (m, 1H),
1.99—1.85 (m, 1H), 1.85—1.70 (m, 2H), 1.45 (s, 3H), 0.99 (d, Jꢀ6.0 Hz,
3H), 0.82 (d, Jꢀ7.2 Hz, 3H); Anal. Calcd for C32H36FNO7 (in %): C, 67.95;
H, 6.42; N, 2.48; Found C, 67.93; H, 6.46 and N, 2.43.
(10S)-N-{4-[3-(1,3-Benzodioxo-5-yl)-2-(E)-propenoyl]phenyloxyacetyl}-
aminodihydroartemisinin (10l): This compound was obtained as yellow solid
in 78% yield. mp: 118—121 °C; MS (ESI) m/z: 614.1 (MꢂNa)ꢂ; IR (KBr)
cmꢄ1: 3420.2, 2925.1, 1657.1, 1601.5, 1529.8, 1504.7, 1489.9, 1447.3,
1
1249.6, 1171.8, 1113.8, 1037.3, 927.1, 808.9, 598.4; H-NMR (300 MHz,
CDCl3) d: 8.07 (d, Jꢀ8.9 Hz, 2H), 7.76 (d, Jꢀ15.5 Hz, 1H), 7.39 (d,
Jꢀ15.5 Hz, 1H), 7.19 (s, 1H), 7.15 (d, Jꢀ8.1 Hz, 1H), 7.06 (d, Jꢀ8.2 Hz,
2H), 6.87 (d, Jꢀ8.1 Hz, 1H), 6.05 (s, 2H), 5.53—5.41 (m, 2H), 4.61 (s, 2H),
2.52—2.31 (m, 2H), 2.11—1.98 (m, 1H), 1.98—1.86 (m, 1H), 1.85—1.70
(m, 2H), 1.45 (s, 3H), 0.99 (d, Jꢀ5.9 Hz, 3H), 0.81 (d, Jꢀ7.2 Hz, 3H); Anal.
Calcd for C33H37NO9 (in %): C, 66.99; H, 6.30; N, 2.37; Found C, 66.95; H,
6.42 and N, 2.36.
(10S)-N-{4-[3-(4-Chlorophenyl)-2-(E)-propenoyl]phenyloxyacetyl}amino
-
dihydroartemisinin (10f): This compound was obtained as pale yellow solid
in 82% yield. mp: 109—111 °C; MS (ESI) m/z: 604.1 (MꢂNa)ꢂ; IR (KBr)
cmꢄ1: 3419.2 2926.0, 2873.3, 1692.2, 1661.2, 1604.5, 1532.0, 1337.0,
1
1217.7, 1172.1, 1114.6, 1037.8, 767.7, 563.5; H-NMR (300 MHz, CDCl3)
d: 8.09 (d, Jꢀ8.9 Hz, 2H), 7.84 (d, Jꢀ15.7 Hz, 1H), 7.68 (d, Jꢀ7.5 Hz, 2H),
7.56 (d, Jꢀ15.7 Hz, 1H), 7.44 (d, Jꢀ7.5 Hz, 2H), 7.07 (d, Jꢀ8.9 Hz, 2H),
5.52—5.42 (m, 2H), 4.62 (s, 2H), 2.53—2.32 (m, 2H), 2.11—2.01 (m, 1H),
1.98—1.86 (m,1H), 1.85—1.71 (m, 2H), 1.45 (s, 3H), 1.00 (d, Jꢀ6.0 Hz,
3H), 0.82 (d, Jꢀ7.2 Hz, 3H); Anal. Calcd for C32H36ClNO7 (in %): C, 66.03;
H, 6.23; N, 2.41; Found C, 65.95; H, 6.35 and N, 2.40.
Anti-tumor Activity Assay in Vitro The anti-tumor activities of com-
pounds 9a—l and 10a—l were evaluated with HT-29, A549, MDA-MB-231,
HeLa, and H460 cell lines by the standard MTT assay in vitro, with DHA as
the positive control. The cancer cell lines were cultured in minimum essen-
tial medium (MEM) supplement with 10% fetal bovine serum (FBS).
Approximately 4ꢃ103 cells, suspended in MEM, were plated onto each
well of a 96-well plate and incubated in 5% CO2 at 37 °C for 24 h. The test
compounds at indicated final concentrations were added to the culture
medium and the cell cultures were continued for 72 h. Fresh MTT was added
to each well at a terminal concentration of 5 mg/ml and incubated with cells
at 37 °C for 4 h. The formazan crystals were dissolved in 100 ml dimethyl
sulfoxide (DMSO) each well, and the absorbency at 492 nm (for absorbance
of MTT formazan) and 630 nm (for the reference wavelength) was measured
with the enzyme-linked immunosorbent assay (ELISA) reader. All of the
compounds were tested twice in each of the cell lines. The results expressed
as IC50 (inhibitory concentration 50%) were the averages of two determina-
tions and calculated by using the Bacus Laboratories Inc. Slide Scanner
(Bliss) software.
(10S)-N-{4-[3-(2,6-Dichlorophenyl)-2-(E)-propenoyl]phenyloxyacetyl}-
aminodihydroartemisinin (10g): This compound was obtained as brown
solid in 81% yield. mp: 122—125 °C; MS (ESI) m/z: 637.9 (MꢂNa)ꢂ; IR
(KBr) cmꢄ1: 3422.1, 2925.9, 2873.2, 1666.4, 1599.8, 1533.3, 1508.7,
1
1221.9, 1172.1, 1114.9, 1039.0, 776.8, 596.3; H-NMR (300 MHz, CDCl3)
d: 8.71 (d, Jꢀ5.1 Hz, 2H), 8.11—8.05 (m, 3H), 7.67 (d, Jꢀ16.8 Hz, 1H),
7.49 (d, Jꢀ5.0 Hz, 2H), 7.07 (d, Jꢀ8.9 Hz, 2H), 5.52—5.41 (m, 2H), 4.62
(s, 2H), 2.52—2.31 (m, 2H), 2.11—2.00 (m, 1H), 1.97—1.86 (m, 1H),
1.83—1.70 (m, 2H), 1.44 (s, 3H), 0.98 (d, Jꢀ5.9 Hz, 3H), 0.81 (d,
Jꢀ7.2 Hz, 3H); Anal. Calcd for C32H35Cl2NO7 (in %): C, 62.34; H, 5.72; N,
2.27; Found C, 62.31; H, 5.79 and N, 2.26.
(10S)-N-{4-[3-(3-Methoxyphenyl)-2-(E)-propenoyl]phenyloxyacetyl}-
aminodihydroartemisinin (10h): This compound was obtained as pale yellow
solid in 84% yield. mp: 105—107 °C; MS (ESI) m/z: 600.1 (MꢂNa)ꢂ; IR
(KBr) cmꢄ1: 3424.2, 2926.2, 2872.9, 1686.2, 1659.4, 1603.4, 1578.8,
1
Acknowledgments This work was supported by the National S&T
Major Project of China (No. 2009ZX09301-012) and the Science Project of
Liaoning Province Education Department (No. L2010532).
1254.5, 1214.3, 1172.2, 1115.3, 1038.8, 834.7, 574.9; H-NMR (300 MHz,
DMSO-d6) d: 8.18 (d, Jꢀ8.9 Hz, 2H), 7.96 (d, Jꢀ15.6 Hz, 1H), 7.68 (d,
Jꢀ15.6 Hz, 1H), 7.48 (s, 1H), 7.44 (d, Jꢀ7.8 Hz, 1H), 7.38 (d, Jꢀ7.9 Hz,
1H), 7.11 (d, Jꢀ8.9 Hz, 2H), 7.07—6.99 (m, 1H), 5.47 (s, 1H), 5.17 (t,
Jꢀ9.8 Hz, 1H), 4.72 (s, 2H), 3.83 (s, 3H), 2.45—2.34 (m, 1H), 2.28—2.12
(m, 1H), 2.04—1.94 (m, 1H), 1.88—1.75 (m, 1H), 1.29 (s, 3H), 0.89 (d,
Jꢀ6.3 Hz, 3H), 0.71 (d, Jꢀ7.1 Hz, 3H); Anal. Calcd for C33H39NO8 (in %):
C, 68.61; H, 6.80; N, 2.42; Found C, 68.52; H, 6.86 and N, 2.41.
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