Synthesis and cytotoxicity of novel 10-substituted dihydroartemisinin derivatives containing N-arylphenyl-ethenesulfonamide groups

Article abstract of DOI:10.3390/molecules18032864

The manuscript describes the synthesis of 10-substituted dihydroartemisinin derivatives containing N-aryl phenylethenesulfonamide groups and their in vitro anti-tumor activities against the HT-29, MDA-MB-231, U87MG, H460, A549 and HL-60 cancer cell lines and the normal WI-38 cell line. Most tested compounds showed enhanced cytotoxic activities and good selectivity toward the MDA-MB-231, HT-29 and HL-60 cell lines, with IC₅₀ values in the single-digit μM range as compared with dihydroartemisinin (DHA), and all of them displayed less toxicity towards WI-38 cells. Among them, compounds 3c and 6c with trifluoromethoxy groups on the N-phenyl ring were found to be most active compounds against the six tested cancer cell lines.

Full text of DOI:10.3390/molecules18032864

Molecules 2013, 18, 2864-2877; doi:10.3390/molecules18032864
OPEN ACCESS
molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
Synthesis and Cytotoxicity of Novel 10-Substituted
Dihydroartemisinin Derivatives Containing
N-Arylphenyl-ethenesulfonamide Groups
Yajing Liu, Zijian Liu, Jiyue Shi, Huimin Chen, Bin Mi, Peng Li and Ping Gong *
Key Laboratory of Original New Drug Design and Discovery of Ministry of Education,
School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang 110016, China
* Author to whom correspondence should be addressed; E-Mail: gongpinggp@126.com;
Tel./Fax: +86-24-2398-6429.
Received: 4 December 2012; in revised form: 28 December 2012 / Accepted: 31 December 2012 /
Published: 4 March 2013
Abstract: The manuscript describes the synthesis of 10-substituted dihydroartemisinin
derivatives containing N-aryl phenylethenesulfonamide groups and their in vitro anti-tumor
activities against the HT-29, MDA-MB-231, U87MG, H460, A549 and HL-60 cancer cell
lines and the normal WI-38 cell line. Most tested compounds showed enhanced cytotoxic
activities and good selectivity toward the MDA-MB-231, HT-29 and HL-60 cell lines, with
IC50 values in the single-digit μM range as compared with dihydroartemisinin (DHA), and
all of them displayed less toxicity towards WI-38 cells. Among them, compounds 3c and 6c
with trifluoromethoxy groups on the N-phenyl ring were found to be most active compounds
against the six tested cancer cell lines.
Keywords: 10-substituted dihydroartemisinin derivatives; synthesis; anti-cancer
1. Introduction
Artemisinin is a sesquiterpene lactone isolated from the plant Artemesia annua L. Artemisinin and its
derivatives, such as dihydroartemisinin (DHA) [1], artemether, arteether, and artesunate [2], are widely
used currently as front-line antimalarials [3,4]. Despite the reported neurotoxic and embryotoxic
effects in animals occurring at higher doses, application of artemisinins in humans seems to be relatively
safe [5]. In addition to their well-known antimalarial activity, artemisinin derivatives possess cytotoxic
activity against cancer cells by inducing apoptosis [6], but high concentrations are required [7].

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Therefore, the synthesis of new, structurally modified derivatives of artemisinin is essential. The high
chemical sensitivity of the artemisinin molecule restricts broad derivatization for library synthesis for
further clinical development. So far the majority of the artemisinin derivatizations were carried out on the
C-10 acetal and to a lesser extent on the C-13 carbon [8]. The observation that dihydroartemisinin C-10
ester, ether or amide derivatives (Figure 1) possess significant antitumor activity prompted previous
efforts, both within our group [9,10] and by others [11–13].
Figure 1. Structures of artesiminin derivatives.
Hybrid drugs are formed by covalently linking two distinct chemical moieties with different biological
modes of action with the aim of creating binary therapies with improved biological activity and less
susceptible to the development of drug resistance [14,15]. Some N-aryl-2-arylethenesulfonamides, a new
class of small molecule antitubulin agents, have exhibited potent activity against a wide spectrum of cancer
cell lines, especially including some drug-resistant cell lines (e.g., MES-SA, HCT116, MDA-MB, etc.).
Among them, ON 24160 (5, Figure 2) was the most promising compound, with significant cytotoxicity
against multiple cancer cell lines and a suitable pharmacokinetic profile [16,17]. Therefore, we have
now synthesized a short series of dihydroartemisinin derivatives 3a–h in which the C-10 hydroxy was
covalently linked to the N-aryl-2-arylethenesulfonamide moiety with a two-carbon chain (Figure 2).
To expand the search for new antitumor compounds, the N-methylbenzamide scaffold was next inserted
into the two-carbon chain linker to obtain compounds 6a to 6j (Figure 2).
Figure 2. Design strategy for target compounds.

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In this study, the synthesis of novel N-aryl phenylethenesulfonamides dihydroartemisinin derivatives
(compounds 3a–h and 6a–j, Figure 2) was reported. Most of them exhibited potent cytotoxic activity
against six human cancer cell lines, including the HT-29, MDA-MB-231, U87MG, H460, A549 and
HL-60 cell lines.
2. Results and Discussion
2.1. Chemistry
The syntheses of target compounds 3a–h and 6a–j are outlined in Scheme 1. Reduction of artemisinin
(1) with NaBH4 gave dihydroartemisinin (2) as mixture of 10α and 10β epimers which reacted with
2-bromoethanol directly using the Lewis acid BF3·Et2O as catalyst to give 10-bromoethoxydihydro-
artemisinin (3) [18]. In our previous report, the stereochemistry of compound 3 had already been
1
determined as 10β by the H-NMR coupling constant (J = 3.4 Hz) between 9-H and 10-H and the
chemical shift of 10-H (4.77 ppm) [9]. Subsequently, the target compounds 3a–h were prepared in
reasonable yield by potassium iodide-catalyzed substitution of bromo compound 3 with N-aryl-4-
hydroxyphenylethane-sulfonamides 10 in the presence of potassium carbonate.
Scheme 1. The synthetic route to the target compounds.
Reagents and conditions: (a) NaBH4, methanol, 0 °C, 2 h; (b) 2-bromoethanol, BF3·Et2O,
dichloromethane, 0 °C, 1 h; (c) NaN3, NaI, DMF, 60 °C, 7 h; (d) (1) PPh3, THF, 60 °C, 2 h; (2) H2O,
70 °C, 1 h; (e) 4-(chloromethyl)benzoyl chloride, DMF, r.t., 1 h; (f) intermediate 10, K2CO3, KI, acetone,
50 °C to reflux, 2 to 7 h.

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Regarding the side chain, N-aryl-2-arylethenesulfonamide derivatives 10 were prepared from ethyl
bromoacetate according to Scheme 2. Reaction of ethyl bromoacetate with Na2SO3 afforded sodium
2-ethoxy-2-oxoethanesulfonate (7), which was converted to the sulfonyl chloride 8 via chlorination
using POCl3. Then condensation of compound 8 with the corresponding substituted anilines in toluene gave
the ethyl 2-(N-arylsulfamonyl)acetates 9. Finally, reaction of compounds 9 with 4-hydroxybenzaldehyde
afforded the desired side chains 10 in high yield.
Scheme 2. The synthetic route to the side chain 10.
Reagents and conditions: (a) Na2SO3, ethanol, H2O, 50 °C, 1 h; (b) POCl3, 80 °C, 2 h; (c) substituted aniline,
triethylamine, toluene, r.t., 0.5 h; (d) 4-hydroxybenzaldehyde, pyridine, ammonium acetate, toluene, 110 °C, 8 h.
The target compounds 6a–j with the extend side chain were prepared from intermediate 3. Firstly,
treatment of 3 with sodium azide under sodium iodide catalysis in DMF according to a modified
Haynes’ method [19] gave 10β-azidoethoxydihydroartemisinin (4). The Staudinger reduction was used
in the transformation of azido compound 4 to 10β-aminoethoxydihydroartemisinin (5). Acylation of the
amino group of 5 yielded 10β-arylamidoethoxydihydroartemisinin (6). Compounds 6a–j were prepared
using a procedure similar to that used to synthesize compounds 3a–h.
The formation of the four key intermediates 3–6 was confirmed by 1H-NMR and LC-MS data, The
1
formation of the title compounds 3a–h and 6a–j was evidenced by their H-NMR, IR and LC-MS
spectra, explained in the Experimental section.
2.2. Biological Activity
The cytotoxic activities of target compounds were evaluated against HT-29 (human colon cancer),
MDA-MB-231 (human breast cancer), U87MG (human glioblastoma), H460 (human lung cancer),
A549 (non-small-cell lung adenocarcinoma), HL-60 (human leukemic) cancer cell lines and one normal
cell line WI-38 (human fetal lung fibroblasts) together with references DHA and cisplatin by a MTT
assay. The results, expressed as averaged IC50 values from at least three independent experiments, are
summarized in Table 1.
As illustrated in Table 1, all of the target compounds showed moderate to excellent cytotoxic
activities against the different cancer cell lines in the single-digit μM range, and displayed less toxicity
against normal WI-38 cells. In general, most of the compounds displayed significant selectivity toward
MDA-MB-231, HT-29 and HL-60 cancer cells. It was worth noting that compounds 3c and 6c exhibited
excellent anti-tumor activities against MDA-MB-231, HT-29 and HL-60 cells with IC50 values in the
tenths of a digit nM range. Moreover, the selectivity index (IC50 normal cell/IC50 cancer cell) of
compound 3c for HL-60 was 750, which demonstrated that the tumor cells were more sensitive than the
normal cells.

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Table 1. Structures and cytotoxicity of compounds against HT-29, MDA-MB-231, U87MG,
H460, A549, HL-60 and WI38 cell lines.
IC50(μM) a
Compd.
R
MDA HT29 U87MG H460 A549 HL-60 WI38
3a
3b
H
3-chloro
2.00
1.61
0.39
1.27
1.64
1.04
0.93
1.07
0.49
2.23
2.26
1.33
2.10
2.38
8.89
0.68
0.78
0.20
1.78
0.86
0.42
0.55
0.49
0.29
1.11
0.98
1.82
2.09
0.92
8.95
0.38
0.45
0.44
5.60
3.97
3.51
1.59
5.71
2.73
0.79
1.78
2.51
3.71
4.52
6.47
17.24
3.65
1.59
>100
3.27
2.69
3.12
15.82
5.38
7.32
0.97
4.29
1.58
1.41
2.53
1.28
2.70
2.79
5.28
2.16
4.48
2.11
3.64
7.32
3.52
3.05
4.33
1.57
2.86
3.21
1.25
0.75
0.05
0.84
2.37
0.08
0.17
0.14
0.09
1.81
2.41
1.30
3.21
1.33
8.53
1.27
0.27
0.18
5.29
9.28
16.75
23.88
37.47
20.53
16.44
19.88
16.33
20.74
28.17
35.76
20.04
19.28
16.39
24.70
19.21
30.37
27.20
23.5
3c
4-trifluoromethoxy
2-fluoro-5-methyl
2-methyl
3d
3e
3f
4-chloro
3g
2-chloro
3h
2,6-dichloro
4-trifluoromethoxy
3-chloro
6c
6b
6a
H
6d
2-fluoro-5-methyl
2-methyl
10.88 9.72
6e
1.92
1.77
5.47
5.72
6f
4-chloro
6i
3-methoxy
16.32 11.34
6j
4-fluoro-3-trifluoromethyl 1.05
5.31
0.89
1.21
2.78
5.31
2.34
6g
2-chloro
0.72
0.88
9.80
6h
2,6-dichloro
DHA b
Cisplatin b
12.37 10.14
7.55 4.31
>100
51.22
6.82 10.31
8.21
a
NA: compound showing IC50 value > 200 μM. ND: not determined. IC50: concentration of the compound
(μM) producing 50% cell growth inhibition after 72 h of drug exposure, as determined by the MTT assay. Each
experiment was run at least three times, and the results are presented as average values ± standard deviation.
b Used as a positive control.
Analysis of Table 1 clearly reveals that the cytotoxicities of benzamide derivatives 6a–j were lower
than those of the corresponding compounds 3a–h. For example, the activity of compound 3c was 2-, 3-
and 2-fold higher than that of benzamide analog 6c against U87MG, H460 and HL-60, respectively. In
addition, it is worth mentioning that different biological properties were observed when a variety of
groups were introduced into the N-phenyl moieties. The activities of compounds 3b, 3d, 3f–h, 6b, 6d
and 6f–h, with the electron-withdrawing halide atoms on the N-phenyl moiety, were superior to those
with electron-donating groups such as methoxy, or methyl groups or no substitutents (6i, 3e, 6e, 3a
and 6a). In the first series of compounds (3a–h), the 4-chloro derivative (3f) was superior to the
fluoro-substituted (3d), disubstituted (3h) or compounds substituted at other positions (3b,g).
Nevertheless, the 2-chloro and 2,6-dichloro derivatives 6g,h were better than others in the second series

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of compounds (6a–j). Excitingly, the compounds with a trifluoromethoxy group at the 4-position of the
N-phenyl exhibited exceptionally high potency in two series of compounds, as exemplified by
compounds 3c and 6c.
3. Experimental
3.1. General
Melting points were measured with a Büchi Melting Point B-540 apparatus (Büchi Labortechnik,
Flawil, Switzerland) and are uncorrected. Mass spectra (MS) were taken in ESI mode on Agilent 1100
1
LC-MS (Agilent, Palo Alto, CA, USA). H-NMR spectra were performed using Bruker 300 MHz
spectrometers (Bruker Bioscience, Billerica, MA, USA) with TMS as an internal standard. IR spectra
(KBr disks) were recorded with a Bruker IFS 55 instrument (Bruker). Elemental analysis was
determined on a Carlo-Erba 1106 Elemental analysis instrument (Carlo Erba, Milan, Italy). Unless
otherwise noted, all the materials were obtained from commercially available sources and were used
without further purification.
Preparation of Dihydroartemisinin (2). NaBH4 (12 g, 0.32 mol) was added slowly to a stirred solution
of artemisinin (30 g, 0.11 mol) in methanol (300 mL) at −5~0 °C. The reaction mixture was stirred at 0 °C
for 2 h, adjusted to pH 6 to 7 with acetic acid, and then concentrated under reduced pressure. The residue
was poured into water (400 mL), and the solid product formed was collected by filtration, washed with
water, and dried to yield compound 2 (25 g, 84%). m.p.: 145–148 °C; MS (ESI, m/z): 283.3 (M−H)–.
.
Preparation of 2-(10β-Dihydroartemisinoxy)ethyl Bromide (3). BF3 Et2O (16 mL) was added to a
solution of dihydroartemisinin 2 (20 g, 70 mmol) and 2-bromoethanol (13 g, 0.11 mol) in CH2Cl2 (100 mL)
below 0 °C. The mixture was stirred at room temperature until the reaction completed, and then was
washed with saturated NaHCO3 solution, water and saturated NaCl solution. The organic layer was dried
and concentrated. The residue was recrystallized from petroleum ether to give compound 3 (13 g, 46%)
as white crystals. m.p.: 155–158 °C; MS (ESI, m/z): 413.2 (M+Na)+; 1H-NMR (300 MHz, DMSO-d6) δ:
5.43 (s, 1H), 4.77 (d, J = 3.4 Hz, 1H), 3.94 (td, J = 9.3, 4.1 Hz, 1H), 3.78 (m, 3H), 2.47 (m, 1H), 2.25 (m,
1H), 2.05 (m, 1H), 1.89–1.75 (m, 2H), 1.61 (m, 2H), 1.44–1.31 (m, 3H), 1.29 (s, 3H), 1.22–1.06 (m, 2H),
0.90 (d, J = 6.5 Hz, 3H), 0.87 (d, J = 7.5 Hz, 3H).
Preparation of 2-(10β-Dihydroartemisinoxy)ethyl Azide (4). NaN3 (4.0 g, 60 mmol) was added to a
stirred solution of compound 3 (8.0 g, 21 mmol) and sodium iodide (0.15 g, 1 mmol) in DMF (60 mL).
The reaction mixture was heated to 60 °C for 3–5 h. The mixture was poured into ice water, stirred for 1 h
and separated by filtration to give white compound 4 (7.1 g, 98%). m.p.: 86–88 °C; MS (ESI, m/z):
376.2 (M+Na)+; 1H-NMR (300 MHz, DMSO-d6) δ: 5.39 (s, 1H), 4.76 (d, J = 3.3 Hz, 1H), 3.91 (m, 1H),
3.56 (m, 3H), 2.47 (m, 1H), 2.25 (m, 1H), 2.06 (m, 1H), 1.87 (m, 4H), 1.45 (m, 3H), 1.29(s, 3H),
1.14 (m, 2H), 0.90 (d, J = 3.8 Hz, 3H), 0.88 (d, J = 4.9 Hz, 3H).
Preparation of 2-(10β-Dihydroartemisinoxy)ethylamine (5). A 100 mL round-bottomed flask was
charged with compound 4 (6.0 g, 17 mmol) and THF (60 mL). To this solution, triphenylphosphine (7.2 g,
27 mmol) was added slowly, and the reaction mixture was stirred for 2 h at 60 °C. Several drops of water

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(1.0 mL, 56 mmol) were 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 chromatography
(silica gel, dichloromethane/methanol, 200:1) to afford the desired compound 5 (4.1 g, 74%) as yellow
oil. MS (ESI, m/z): 328.1 (M+H)+; 1H-NMR (300 MHz, DMSO-d6) δ: 5.34 (s, 1H), 4.69 (d, J = 3.4 Hz,
1H), 3.71 (m, 1H), 3.30 (dt, J = 9.8, 5.7 Hz, 1H), 2.73 (m, 2H), 2.47 (m, 1H), 2.25 (m, 1H), 2.07 (m, 1H),
1.86 (m, 2H), 1.78 (m, 2H), 1.63 (m, 3H), 1.29 (s, 3H), 1.21–1.07 (m, 2H), 0.89 (d, J = 6.3 Hz, 3H),
0.85 (d, J = 7.4 Hz, 3H).
Preparation of 4-(Chloromethyl)-N-2-(10β-dihydroartemisinoxy)ethyl Benzamide (6). A solution of
compound 5 (4.0 g, 12 mmol) in DMF (20 mL) was cooled below 0 °C and 4-(chloromethyl)benzoyl
chloride (2.3 g, 12 mmol) was added dropwise. The mixture was stirred at room temperature for 1 h, and
then poured into water. The white precipitate was filtered, washed with ethanol, and dried to obtain 6
(5.1 g, 87%). m.p.: 105–108 °C; MS (ESI, m/z): 480.9 (M+H)+; 1H-NMR (300 MHz, DMSO-d6) δ: 7.93
(d, J = 7.2 Hz, 2H), 7.51 (d, J = 7.2 Hz, 2H), 5.38 (s, 1H), 4.71 (d, J = 3.4 Hz, 1H), 4.54 (s, 2H), 3.73 (m,
1H), 3.32 (dt, J = 9.8, 5.7 Hz, 1H), 2.75 (m, 2H), 2.49 (m, 1H), 2.28 (m, 1H), 2.11 (m, 1H), 1.89 (m, 2H),
1.80 (m, 2H), 1.65 (m, 3H), 1.31 (s, 3H), 1.24 (m, 2H), 0.92 (d, J = 6.4 Hz, 3H), 0.87 (d, J = 7.4 Hz, 3H).
Preparation of Sodium 2-Ethoxy-2-oxoethanesulfonate (7). Na2SO3 (15 g, 0.12 mol) was dissolved in
water (50 mL) and a solution of ethyl bromoacetate (20 g, 0.12 mol) in ethanol (25 mL) was added
dropwise at 5–10 °C. The reaction mixture was heated to 50 °C for 1 h. After then, the solution was
evaporated until dryness. Acetic acid (200 mL) and ethyl acetate (100 mL) were added to the residue,
and the mixture was heated to 100 °C for 1 h. The hot mixture was filtered, and another 1,000 mL ethyl
acetate was poured into the filtrate. The white crystals were filtered, washed with ethyl acetate, and dried
to yield white solid 7 (23 g, 99%). m.p.: 158 °C (dec.); MS (ESI, m/z): 190.2 (M+Na)+.
Preparation of Ethyl 2-(Chlorosulfonyl)acetate (8) A mixture of compound 7 (10 g, 0.053 mol) and
POCl3 (100 mL, 1.1 mol) was stirred at 80 °C for 2 h and then cooled to room temperature. The solvent
was removed under vacuum, 100 mL of toluene was added, and stirred for 10 min. The reaction solution
was filtered, and the solvent was evaporated under reduced pressure to obtain 8 (9.0 g, 92%) as a red oil.
3.2. General Procedure for the Preparation of Ethyl 2-(N-Arylsulfamoyl)acetate (9)
A solution of 8 (8.0 g, 0.043 mol) in toluene (100 mL) was cooled to −5~0 °C, a mixture of
substituted aniline (0.086 mol), triethylamine (0.065 mol) in toluene (50 mL) was added dropwise. The
reaction mixture was stirred at room temperature for 0.5–1 h, and then washed with water, 5% HCl,
saturated NaHCO3 solution, saturated NaCl solution and water. The organic phase was dried with
Na2SO4 and evaporated to yield 9 as a brown oil.
3.3. General Procedure for the Preparation of Ethyl 2-(4-Hydroxyphenyl)-N-arylethenesulfonamides 10
A mixture of compound 9 (0.02 mol), 4-hydroxybenzaldehyde (5.0 g, 0.04 mol), pyridine (0.40 mL,
5.0 mmol), ammonium acetate (0.40 g, 5.0 mmol) and toluene (100 mL) was stirred at 110 °C for 8–10 h
and then cooled to room temperature. The toluene phase was washed with 5% HCl, saturated NaHCO3
solution and water, dried with Na2SO4 to obtain 10 as a brick red oil.

Molecules 2013, 18
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3.4. General Procedure for the Preparation of Target Compounds 3a–h
A mixture of compound 3 (10 g, 0.026 mol), 10 (0.026 mol), K2CO3 (5.4 g, 0.039 mol), KI (0.40 g,
2.6 mmol) and acetone (100 mL) was stirred at 50 °C for 2–3 h. The reaction solvent was evaporated and
the residue was purified by column chromatography (silica-gel, 1%–5% petroleum ether/ethyl acetate)
to afford pure compounds 3a–h.
3.5. General Procedure for the Preparation of Target Compounds 6a–j
A mixture of compound 10 (0.024 mol), K2CO3 (4.2 g, 0.03 mol) and acetone (100 mL) was stirred at
room temperature for 10 min, and then compound 6 (9.6 g, 0.02 mol) and KI (0.4 g, 2.6 mmol) was
added while the reaction refluxed for 7–9 h. The acetone was removed under vacuum, and CH2Cl2 (100 mL)
was poured into the residue. The solution was washed with water, dried with Na2SO4. The solvent was
evaporated and the residue was purified by column chromatography (silica-gel, 1%–5% petroleum
ether/ethyl acetate) to afford pure compounds 6a–j.
(E)-2-(4-(2-(10β-Dihydroartemisinoxy)ethoxy)phenyl)-N-phenylethenesulfonamide (3a). Light yellow
solid (38% yield); m.p.: 136–138 °C; MS (ESI) m/z: 584.2 (M-H)–; IR (KBr) cm−1: 3422.1, 2923.1,
1603.8, 1514.4, 1343.4, 1147.5, 1027.3, 983.5, 696.9, 597.1; 1H-NMR (300 MHz, DMSO-d6) δ: 7.54 (d,
J = 7.2 Hz, 2H), 7.35 (m, 5H), 7.15 (d, J = 15.2 Hz, 1H), 7.05 (d, J = 15.2 Hz, 1H), 6.79 (d, J = 7.5 Hz,
2H), 5.22 (s, 1H), 4.60 (s, 1H), 3.80 (m, 2H), 3.70 (m, 2H), 3.28 (m, 1H), 2.83 (m, 2H), 2.49 (m, 1H),
2.33 (m, 1H), 2.16 (m, 1H), 1.99 (m, 1H), 1.76 (m, 1H), 1.47 (m, 1H), 1.28 (m, 2H), 1.26 (s, 3H), 1.08
(s, 1H), 0.88 (d, J = 4.8 Hz, 3H), 0.75 (d, J = 7.1 Hz, 3H). Anal. Calcd. for C31H39NO8S: C 63.57, H 6.71,
N 2.39. Found: C 63.52, H 6.50, N 2.41.
(E)-2-(4-(2-(10β-Dihydroartemisinoxy)ethoxy)phenyl)-N-(3-chlorophenyl)ethenesulfonamide (3b). Light
yellow solid (44% yield); m.p.: 137–138 °C; MS (ESI) m/z: 618.0 (M−H)–; IR (KBr) cm−1: 3477.3,
1
2923.4, 1603.4, 1514.3, 1343.9, 1148.9, 1027.6, 983.4, 788.6, 597.7; H-NMR (300 MHz, DMSO-d6)
δ 10.12(br, 1H), 7.58 (d, J = 8.6 Hz, 2H), 7.45 (m, 4H), 7.19 (d, J = 15.3 Hz, 1H), 7.08 (d, J = 15.3 Hz,
1H), 6.80 (d, J = 8.6 Hz, 2H), 5.22 (s, 1H), 4.60 (d, J = 3.1 Hz, 1H), 3.83 (m, 2H), 3.71 (m, 2H), 3.04
(s, 1H), 2.32 (m, 2H), 2.13 (d, J = 10.0 Hz, 1H), 2.00 (t, J = 13.9 Hz, 1H), 1.76 (m, 1H), 1.45 (m, 2H),
1.25 (d, J = 8.7 Hz, 5H), 1.11 (d, J = 18.8 Hz, 2H), 0.88 (d, J = 6.2 Hz, 3H), 0.72 (d, J = 7.4 Hz, 3H).
Anal. Calcd. for C31H38ClNO8S: C 60.04, H 6.18, N 2.26. Found: C 59.98, H 6.21, N 2.19.
(E)-2-(4-(2-(10β-Dihydroartemisinoxy)ethoxy)phenyl)-N-(4-trifluoromethoxyphenyl)ethenesulfonamide (3c).
Yellow solid (42% yield); m.p.: 139–142 °C; MS (ESI) m/z: 692.1 (M+Na)+; IR (KBr) cm−1: 3416.7,
1
2924.6, 1604.1, 1510.7, 1346.0, 1258.8, 1224.3, 1027.9, 983.6, 838.8, 504.3; H-NMR (300 MHz,
DMSO-d6) δ 10.06 (br, 1H), 7.56 (d, J = 8.5 Hz, 2H), 7.48 (d, J = 8.9 Hz, 2H), 7.37 (d, J = 8.5 Hz,
2H), 7.19 (d, J = 15.3 Hz, 1H), 7.08 (d, J = 15.3 Hz, 1H), 6.79 (d, J = 8.6 Hz, 2H), 5.21 (s, 1H), 4.60
(d, J = 3.3 Hz, 1H), 3.82 (m, 2H), 3.76 (m, 2H), 2.32 (m, 1H), 2.15 (m, 1H), 2.00 (m, 1H), 1.76 (m,
1H), 1.46 (m, 2H), 1.41 (m, 1H), 1.26 (m, 6H), 1.09 (m, 2H), 0.87 (m, 3H), 0.70 (d, J = 7.3 Hz, 3H).
Anal. Calcd. for C32H38F3NO9S: C 57.39, H 5.72, N 2.09. Found: C 57.41, H 5.68, N 2.11.

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(E)-2-(4-(2-(10β-Dihydroartemisinoxy)ethoxy)phenyl)-N-(2-fluoro-5-methylphenyl)ethenesulfonamide (3d).
Light yellow solid (36% yield); m.p.: 138–140 °C; MS (ESI) m/z: 640.1 (M+Na)+; IR (KBr) cm−1:
1
3424.5, 2923.5, 1604.1, 1510.7, 1343.8, 1148.7, 1028.1, 984.6, 872.5, 601.1; H-NMR (300 MHz,
DMSO-d6) δ 10.06 (br, 1H), 7.56 (d, J = 8.5 Hz, 2H), 7.24 (m, 2H), 7.18 (m, 2H), 7.09 (d, J = 15.3 Hz,
1H), 6.81 (d, J = 8.6 Hz, 2H), 5.22 (s, 1H), 4.59 (d, J = 3.2 Hz, 1H), 3.72 (m, 4H), 2.26 (m, 1H), 2.15
(s, 3H), 2.10 (m, 1H), 2.00 (m, 1H), 1.77 (m, 1H), 1.40 (m, 3H), 1.28 (m, 6H), 1.09 (m, 2H), 0.87 (d,
J = 5.9 Hz, 3H), 0.71 (d, J = 7.3 Hz, 3H). Anal. Calcd. for C32H40FNO8S: C 62.22, H 6.53, N 2.27.
Found: C 62.19, H 6.55, N 2.29.
(E)-2-(4-(2-(10β-Dihydroartemisinoxy)ethoxy)phenyl)-N-(2-methylphenyl)ethenesulfonamide (3e). Light
brown solid (26% yield); m.p.: 136–138 °C; MS (ESI) m/z: 598.2 (M−H)–; IR (KBr) cm−1: 3414.8,
1
2923.1, 1604.2, 1514.7, 1342.5, 1146.2, 1027.5, 983.6, 872.4, 603.3; H-NMR (300 MHz, DMSO-d6)
δ 7.59 (d, J = 8.5 Hz, 2H), 7.28 (m, 6H), 6.80 (d, J = 8.6 Hz, 2H), 5.15(s, 1H), 4.62 (d, J = 3.3 Hz, 1H),
4.45 (d, J = 5.7 Hz, 1H), 3.82 (m, 2H), 3.70 (m, 2H), 2.35 (s, 3H), 2.07–1.87 (m, 1H), 1.75 (m, 1H), 1.42
(m, 2H), 1.26 (s, 3H), 1.25 (m, 4H), 1.06 (t, J = 7.0 Hz, 2H), 0.86 (d, J = 5.9 Hz, 3H), 0.73 (d, J = 7.3 Hz,
3H). Anal. Calcd. for C32H41NO8S: C 64.09, H 6.89, N 2.34. Found: C 64.13, H 6.81, N 2.39.
(E)-2-(4-(2-(10β-Dihydroartemisinoxy)ethoxy)phenyl)-N-(4-chlorophenyl)ethenesulfonamide (3f). Light
brown solid (44% yield); m.p.: 138–141 °C; MS (ESI) m/z: 618.1 (M−H)–; IR (KBr) cm−1: 3411.5,
1
2925.1, 1601.5, 1490.3, 1343.2, 1149.3, 1054.2, 1027.0, 1007.0, 822.9, 760.8; H-NMR (300 MHz,
DMSO-d6) δ 7.56 (d, J = 8.3 Hz, 1H), 7.43 (m, 3H), 7.18 (m, 2H), 7.01 (d, J = 8.8 Hz, 1H), 6.80 (d,
J = 7.6 Hz, 1H), 6.67 (d, J = 7.0 Hz, 1H), 6.50 (d, J = 9.0 Hz, 1H), 5.17 (s, 1H), 4.76 (d, J = 3.5 Hz,
1H), 4.35 (m, 2H), 3.82 (m, 2H), 3.62 (m, 2H), 2.05 (s, 3H), 1.56 (m, 2H), 1.35 (m, 2H), 1.24 (s, 3H),
1.10 (m, 3H), 0.97 (d, J = 6.0 Hz, 3H), 0.80 (d, J =7.4 Hz, 3H). Anal. Calcd. for C31H38ClNO8S:
C 60.04, H 6.18, N 2.26. Found: C 60.11, H 6.12, N 2.30.
(E)-2-(4-(2-(10β-Dihydroartemisinoxy)ethoxy)phenyl)-N-(2-chlorophenyl)ethenesulfonamide (3g). Yellow
solid (38% yield); m.p.: 141–143 °C; MS (ESI) m/z: 618.2 (M-H)–; IR (KBr) cm−1: 3412.1, 2926.3,
1
1604.2, 1493.5, 1340.3, 1145.7, 1052.8, 1022.4, 828.5, 772.4; H-NMR (300 MHz, DMSO-d6) δ 7.65
(d, J = 8.2 Hz, 2H), 7.45 (m, 2H), 7.28 (m, 2H), 7.20 (d, J = 15.1 Hz, 1H), 7.04 (d, J = 15.1 Hz, 1H),
6.81 (d, J = 8.3 Hz, 2H), 5.27 (s, 1H), 4.62 (d, J = 3.2 Hz, 1H), 3.82 (m, 2H), 3.76 (m, 2H), 3.30
(m, 2H), 2.81 (m, 1H), 2.53 (m, 1H), 2.37 (m, 1H), 2.20 (m, 1H), 2.00 (m, 1H), 1.85 (m, 1H), 1.51
(m, 1H), 1.32 (m, 2H), 1.27 (s, 3H), 1.09 (s, 1H), 0.85 (d, J = 6.8 Hz, 3H), 0.79 (d, J = 7.3 Hz, 3H).
Anal. Calcd. for C31H38ClNO8S: C 60.04, H 6.18, N 2.26. Found: C 59.93, H 6.21, N 2.29.
(E)-2-(4-(2-(10β-Dihydroartemisinoxy)ethoxy)phenyl)-N-(2,6-dichlorophenyl)ethenesulfonamide (3h).
Brown solid (41% yield); m.p.: 144–146 °C; MS (ESI) m/z: 653.1 (M-H)–; IR (KBr) cm−1: 3420.8,
1
2922.6, 1602.6, 1508.2, 1348.2, 1147.1, 1027.8, 984.7, 874.3, 541.5; H-NMR (300 MHz, DMSO-d6)
δ 7.78 (d, J = 8.1 Hz, 2H), 7.28 (m, 2H), 7.15 (d, J = 15.3 Hz, 1H), 6.97 (m, 2H), 6.83 (d, J = 7.9 Hz,
2H), 5.21 (s, 1H), 4.62 (d, J = 3.3 Hz, 1H), 3.82 (m, 4H), 2.31 (m, 2H), 2.16 (s, 2H), 2.12 (m, 1H),
1.98 (m, 1H), 1.75 (m, 2H), 1.39 (m, 2H), 1.26 (m, 6H), 1.07 (m, 2H), 0.89 (d, J = 5.9 Hz, 3H), 0.78
(d, J = 7.4 Hz, 3H). Anal. Calcd. for C31H37Cl2NO8S: C 56.88, H 5.70, N 2.14. Found: C 56.92, H
5.75, N 2.17.

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(E)-N-(2-(10β-Dihydroartemisinoxy)ethyl)-4((4-(2-(N-phenylsulfamoyl)vinyl)phenoxy)methyl)benzamide
(6a). Light yellow solid (48% yield); m.p.: 142–145 °C; MS (ESI) m/z: 717.1 (M-H)–; IR (KBr) cm−1:
3413.1, 2924.1, 1604.2, 1513.9, 1336.6, 1146.1, 1020.8, 873.7, 801.7, 699.4, 603.3; 1H-NMR (300 MHz,
DMSO-d6) δ 8.49 (br, 1H), 7.85 (d, J = 8.1 Hz, 2H), 7.62 (m, 2H), 7.50 (d, J = 8.0 Hz, 2H), 7.33 (d,
J = 15.2 Hz, 1H), 7.24 (t, J = 7.6 Hz, 2H), 7.17 (d, J = 8.1 Hz, 2H), 7.0 (m, 4H), 5.26 (s, 1H), 5.21 (s,
2H), 4.69 (d, J = 3.2 Hz, 1H), 4.44 (d, J = 5.2 Hz, 1H), 4.39 (t, J = 3.9 Hz, 2H), 3.82 (m, 2H), 2.24 (m,
2H), 2.06 (m, 3H), 1.67 (m, 3H), 1.48 (m, 2H), 1.26 (s, 3H), 1.23 (s, 1H), 0.81 (d, J = 7.4 Hz, 3H),
0.68 (d, J = 5.6 Hz, 3H). Anal. Calcd. for C39H46N2O9S: C 65.16, H 6.45, N 3.90. Found: C 65.09,
H 6.43, N 3.96.
(E)-N-(2-(10β-Dihydroartemisinoxy)ethyl)-4((4-(2-(N-(3-chlorophenyl)sulfamoyl)vinyl)phenoxy)methy
l)benzamide (6b). Light yellow solid (45% yield); m.p.: 146–149 °C; MS (ESI) m/z: 751.0 (M-H)–; IR
(KBr) cm−1: 3397.3, 2923.3, 1602.5, 1512.7, 1344.3, 1147.4, 1026.6, 983.7, 872.9, 791.7, 594.8;
1H-NMR (300 MHz, DMSO-d6) δ 8.40 (br, 1H), 7.74 (d, J = 8.2 Hz, 2H), 7.60 (d, J = 8.5 Hz, 2H), 7.50
(d, J = 13.1 Hz, 2H), 7.37 (d, J = 8.2 Hz, 2H), 7.32 (d, J = 4.6 Hz, 2H), 7.26 (d, J = 8.1 Hz, 2H), 6.82
(d, J = 8.2 Hz, 2H), 5.25 (s, 1H), 4.92 (d, J = 13.4 Hz, 2H), 4.68 (d, J = 3.0 Hz, 1H), 3.82 (m, 2H),
3.53(m, 2H), 2.34 (m, 1H), 2.12 (m, 2H), 2.00 (m, 2H), 1.66 (m, 2H), 1.49 (m, 2H), 1.26 (m, 6H), 0.80
(d, J = 7.2 Hz, 3H), 0.65 (d, J = 5.7 Hz, 3H). Anal. Calcd. for C39H45ClN2O9S: C 62.18, H 6.02, N
3.72. Found: C 62.23, H 6.18, N 3.68.
(E)-N-(2-(10β-Dihydroartemisinoxy)ethyl)-4((4-(2-(N-(4-trifluoromethoxyphenyl)sulfamoyl)vinyl)phen
oxy)methyl)benzamide (6c). Yellow solid (43% yield); m.p.: 149–151 °C; MS (ESI) m/z: 801.2 (M−H)–;
IR (KBr) cm−1: 3396.9, 2924.0, 1603.0, 1507.9, 1346.4, 1360.2, 1146.2, 1025.4, 870.5, 801.6, 593.1;
1H-NMR (300 MHz, DMSO-d6) δ 8.38 (br, 1H), 7.74 (d, J = 8.2 Hz, 2H), 7.60 (d, J = 8.5 Hz, 2H),
7.47 (d, J = 9.0 Hz, 2H), 7.37 (d, J = 8.0 Hz, 2H), 7.34 (m, 4H), 6.82 (d, J = 8.2 Hz, 2H), 5.25 (s,
1H), 4.88 (s, 2H), 4.68 (d, J = 3.2 Hz, 1H), 4.45 (m, 1H), 4.35 (m, 1H), 3.82 (s, 2H), 3.62 (m, 1H),
2.35 (m, 1H), 2.11 (m, 1H), 1.96 (m, 1H), 1.65 (m, 3H), 1.51 (m, 1H), 1.25 (m, 7H), 0.79 (d, J = 7.2 Hz,
3H), 0.65 (d, J = 5.8 Hz, 3H). Anal. Calcd. for C40H45F3N2O10S: C 59.84, H 5.65, N 3.49. Found: C
59.93, H 5.69, N 3.52.
(E)-N-(2-(10β-Dihydroartemisinoxy)ethyl)-4((4-(2-(N-(2-fluoro-5-methylphenyl)sulfamoyl)vinyl)pheno
xy)methyl)benzamide (6d) Light yellow solid (35% yield); m.p.: 135–137 °C; MS (ESI) m/z: 749.2
(M-H)–; IR (KBr) cm−1: 3412.2, 2924.6, 1603.9, 1509.1, 1343.9, 1146.1, 1025.8, 984.1, 872.7, 843.9,
597.9; 1H-NMR (300 MHz, DMSO-d6) δ 8.40 (br, 1H), 7.74 (d, J = 8.1 Hz, 2H), 7.60 (d, J = 8.4 Hz,
2H), 7.41(d, J = 8.2 Hz, 2H), 7.28 (s, 1H), 7.20 (m, 2H), 7.13 (m, 2H), 6.83 (d, J = 8.1 Hz, 2H), 5.26
(s, 1H), 4.78 (s, 2H), 4.69 (d, J = 3.3 Hz, 1H), 4.46 (d, J = 3.5 Hz, 1H), 4.39 (m, 1H), 3.82 (m, 2H),
3.52 (m, 2H), 2.34 (m, 1H), 2.19 (s, 3H), 2.10 (m, 1H), 1.94 (m, 1H), 1.66 (m, 2H), 1.52 (m, 1H), 1.38
(s, 1H), 1.25 (m, 6H), 0.80 (d, J = 7.3 Hz, 3H), 0.66 (d, J = 5.6 Hz, 3H). Anal. Calcd. for C40H47FN2O9S:
C 63.98, H 6.31, N 3.73. Found: C 64.02, H 6.37, N 3.68.
(E)-N-(2-(10β-Dihydroartemisinoxy)ethyl)-4((4-(2-(N-(2-methylphenyl)sulfamoyl)vinyl)phenoxy)methyl)
benzamide (6e) Light yellow solid (40% yield); m.p.: 143–145 °C; MS (ESI) m/z: 731.2 (M-H)–; IR
(KBr) cm−1: 3397.2, 2923.2, 1603.4, 1510.1, 1341.8, 1143.7, 1027.5, 984.2, 874.6, 800.3, 594.8;

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1H-NMR (300 MHz, DMSO-d6) δ 8.39 (s, 1H), 7.71 (d, J = 8.1 Hz, 2H), 7.61 (m, 4H), 7.34 (m, 4H),
7.15 (d, J = 8.2 Hz, 2H), 6.83 (d, J = 8.2 Hz, 2H), 5.29 (s, 1H), 4.87 (m, 1H), 4.69 (m, 2H), 3.83 (m,
2H), 3.47 (m, 2H), 2.40 (m, 2H), 2.31 (s, 1H), 2.15 (m, 1H), 2.07 (s, 3H), 1.95 (m, 2H), 1.70 (m, 2H),
1.51 (m, 1H), 1.27 (m, 4H), 1.04 (m, 2H), 0.80 (d, J = 7.3 Hz, 3H), 0.72 (d, J = 4.7 Hz, 3H). Anal.
Calcd. for C40H48N2O9S: C 65.55, H 6.60, N 3.82. Found: C 65.48, H 6.57, N 3.85.
(E)-N-(2-(10β-Dihydroartemisinoxy)ethyl)-4((4-(2-(N-(4-chlorophenyl)sulfamoyl)vinyl)phenoxy)methyl)
benzamide (6f). Yellow solid (39% yield); m.p.: 138–141 °C; MS (ESI) m/z: 751.1 (M-H)–; IR (KBr)
1
cm−1: 3397.1, 2923.1, 1603.4, 1509.9, 1345.8, 1146.5, 1026.2, 982.5, 871.4, 800.5, 594.3; H-NMR
(300 MHz, DMSO-d6) δ 8.39 (br, 1H), 7.72 (d, J = 8.2 Hz, 2H), 7.59 (d, J = 8.5 Hz, 2H), 7.48 (d,
J = 13.1 Hz, 2H), 7.32 (d, J = 8.2 Hz, 2H), 7.28 (d, J = 4.6 Hz, 2H), 7.17 (d, J = 8.1 Hz, 2H), 6.80 (d,
J = 8.2 Hz, 2H), 5.24 (s, 1H), 4.83 (s, 2H), 4.62 (d, J = 3.2 Hz, 1H), 4.41 (m, 1H), 4.30 (m, 1H), 3.81
(s, 2H), 3.60 (m, 1H), 2.33 (m, 1H), 2.08 (m, 1H), 1.93 (m, 1H), 1.61 (m, 3H), 1.47 (m, 2H), 1.26 (m,
6H), 0.78 (d, J = 7.2 Hz, 3H), 0.64 (d, J = 5.8 Hz, 3H). Anal. Calcd. for C39H45ClN2O9S: C 62.18, H
6.02, N 3.72. Found: C 62.23, H 5.98, N 3.76.
(E)-N-(2-(10β-Dihydroartemisinoxy)ethyl)-4((4-(2-(N-(2-chlorophenyl)sulfamoyl)vinyl)phenoxy)methyl)
benzamide (6g). Light yellow solid (38% yield); m.p.: 147–150 °C; MS (ESI) m/z: 775.2 (M+Na)+; IR
(KBr) cm−1: 3394.1,2925.3, 1605.5, 1499.1, 1339.3, 1144.8, 1028.8, 979.5, 881.7, 806.7, 598.2;
1H-NMR (300 MHz, DMSO-d6) δ 7.59 (m, 2H), 7.40 (d, J = 8.6 Hz, 4H), 7.32 (m, 3H), 6.94 (s, 2H),
6.79 (m, 3H), 5.62 (s, 1H), 5.35 (d, J = 10.3 Hz, 1H), 4.80 (s, 2H), 4.68 (d, J = 3.1 Hz, 1H), 3.81 (m,
2H), 3.45 (m, 2H), 2.18 (m, 1H), 2.05 (m, 2H), 1.94 (m, 2H), 1.63 (m, 2H), 1.52 (m, 2H), 1.33 (s, 3H),
0.98 (m, 2H), 0.83 (d, J = 7.4 Hz, 3H), 0.71 (d, J = 5.7 Hz, 3H). Anal. Calcd. for C39H45ClN2O9S:
C 62.18, H 6.02, N 3.72. Found: C 62.12, H 5.97, N 3.79.
(E)-N-(2-(10β-Dihydroartemisinoxy)ethyl)-4((4-(2-(N-(2,6-dichlorophenyl)sulfamoyl)vinyl)phenoxy)m
ethyl)benzamide (6h). Light yellow solid (40% yield); m.p.: 151–153 °C; MS (ESI) m/z: 784.9 (M-H)–;
IR (KBr) cm−1: 3420.8, 2922.6, 1602.6, 1508.2, 1348.2, 1147.1, 1027.8, 984.7, 874.3, 541.5; 1H-NMR
(300 MHz, DMSO-d6) δ 8.40 (br, 1H), 7.75 (d, J = 8.1 Hz, 1H), 7.62 (d, J = 8.3 Hz, 2H), 7.59 (m, 4H),
7.28 (m, 4H), 6.84 (d, J = 7.5 Hz, 2H), 5.26 (s, 1H), 4.80 (s, 2H), 4.69 (d, J = 3.3 Hz, 1H), 3.85 (m,
2H), 3.59 (m, 2H), 2.35 (m, 1H), 2.13 (m, 1H), 1.97 (m, 2H), 1.67 (m, 3H), 1.52 (m, 2H), 1.27 (s, 3H),
1.24 (s, 2H), 1.04 (m, 1H), 0.81 (d, J = 7.4 Hz, 3H), 0.69 (d, J = 4.5 Hz, 3H). Anal. Calcd. for
C39H44Cl2N2O9S: C 59.46, H 5.63, N 3.56. Found: C 59.42, H 5.59, N 3.50.
(E)-N-(2-(10β-Dihydroartemisinoxy)ethyl)-4((4-(2-(N-(3-methoxyphenyl)sulfamoyl)vinyl)phenoxy)met
hyl)benzamide (6i). Light yellow solid (48% yield); m.p.: 144–145 °C; MS (ESI) m/z: 747.2 (M−H)–;
IR (KBr) cm−1: 3392.7, 2923.7, 1603.2, 1512.6, 1340.0, 1142.2, 1025.9, 982.8, 871.7, 840.7, 596.3;
1H-NMR (300 MHz, DMSO-d6) δ 8.40 (br, 1H), 7.74 (d, J = 8.2 Hz, 2H), 7.60 (d, J = 8.5 Hz, 2H),
7.50 (s, 1H), 7.43 (s, 1H), 7.37 (d, J = 8.2 Hz, 2H), 7.32 (d, J = 4.6 Hz, 2H), 7.26 (d, J = 8.1 Hz, 2H),
6.82 (d, J = 8.6 Hz, 2H), 5.25 (s, 1H), 4.92 (d, J = 5.4 Hz, 2H), 4.68 (m, 1H), 3.95(s, 3H), 3.82 (m,
2H), 3.51(m, 2H), 2.34 (m, 2H), 2.12 (m, 2H), 2.00 (m, 2H), 1.66 (m, 2H), 1.49 (m, 1H), 1.26 (s, 3H),
1.21 (m, 3H), 0.81 (d, J = 7.3 Hz, 3H), 0.69 (d, J = 5.2 Hz, 3H). Anal. Calcd. for C40H48N2O10S:
C 64.15, H 6.46, N 3.74. Found: C 64.09, H 6.41, N 3.67.

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(E)-N-(2-(10β-Dihydroartemisinoxy)ethyl)-4((4-(2-(N-(3-trifluoromethyl-4fluorophenyl)sulfamoyl)vinyl)
phenoxy)methyl)benzamide (6j). Yellow solid (32% yield); m.p.: 152–154 °C; MS (ESI) m/z: 803.2
(M-H)–; IR (KBr) cm−1: 3401.8, 2924.7, 1602.3, 1503.7, 1328.9, 1145.3, 1026.0, 983.9, 845.8, 646.6,
1
542.5; H-NMR (300 MHz, DMSO-d6) δ 8.40 (br, 1H), 7.81 (m, 4H), 7.63 (m, 3H), 7.47 (d, J = 15.6
Hz, 1H), 7.37 (t, J = 8.4 Hz, 2H), 7.27 (d, J = 15.6 Hz, 1H), 6.82 (d, J = 8.6 Hz, 2H), 5.24 (s, 1H), 4.98
(s, 1H), 4.93 (s, 2H), 4.68 (d, J = 3.1 Hz, 1H), 3.83 (m, 2H), 3.51 (m, 2H), 2.34 (m, 1H), 2.16 (m, 2H),
1.94 (m, 1H), 1.65 (m, 2H), 1.49 (m, 1H), 1.26 (s, 4H), 1.14 (m, 2H), 1.05 (m, 1H), 0.79 (d, J = 7.3 Hz,
3H), 0.60 (d, J = 6.0 Hz, 3H). Anal. Calcd. for C40H44F4N2O9S: C 59.69, H 5.51, N 3.48. Found:
C 59.74, H 5.46, N 3.41.
3.6. Evaluation of Biological Activity
The cytotoxic activities of compounds 3a–h and 6a–j were evaluated with the HT-29,
MDA-MB-231, U87MG, H460, A549, HL-60 cancer cell lines and one normal cell line, WI-38, by the
standard MTT assay in vitro [20], with DHA as the positive control. The cell lines were cultured in
minimum essential medium (MEM) supplement with 10% fetal bovine serum (FBS). Approximately
4 × 103 cells, suspended in MEM medium, were plated on to 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 μg/mL and incubated with cells at 37 °C for 4 h. The formazan crystals were
dissolved in 100 μL 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 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 determinations and calculated using the Bacus Laboratories Incorporated Slide
Scanner (Bliss) software.
4. Conclusions
In summary, two series of 10-substituted dihydroartemisinin derivatives containing N-aryl
phenylethenesulfonamide groups were prepared. Through anti-tumor activity screening the following
conclusion can be reached about their structure-activity relationships: (a) all the target compounds
were more potent than DHA and displayed less toxicity against the normal cell line WI-38, indicating
that the presence of N-phenyl phenylethenesulfonamides moiety significantly enhanced their antitumor
activities against the six cancer cell lines; (b) most compounds displayed good selectivity for inhibition
of MDA-MB-231, HT-29, and especially the HL-60 cancer cell lines; (c) the substituent on the N-phenyl
ring might play an important role in the tested compounds’ activities. The introduction of halogen,
especially trifluoromethoxy group at the 4-position of the N-phenyl group could enhance the cytotoxic
activities, while methyl or methoxy groups decreased the potency.

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Sample Availability: Samples of the compounds 3a–h and 6a–j are available from the authors.
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