Second generation, orally active, antimalarial, artemisinin-derived trioxane dimers with high stability, efficacy, and anticancer activity

Article abstract of DOI:10.1021/jm058288w

In only two steps and in 63% overall yield, naturally occurring 1,2,4-trioxane artemisinin (1) was converted into C-10-carba trioxane conjugated diene dimer 4. This new dimer was then transformed easily in one additional 4 + 2-cycloaddition step into phthalate dimer 5, and further modification led to bis-benzyl alcohol dimer 7 and its phosphorylated analogues 8 and 9. Bis-benzyl alcohol dimer 7 is the most antimalarially active in vitro, 10 times more potent than artemisinin (1). Bis-benzyl alcohol dimer 7 is approximately 1.5 times more orally efficacious in rodents than the antimalarial drug sodium artesunate and is about 37 times more efficacious than sodium artesunate via subcutaneous administration. Both dimers 5 and 7 are thermally stable neat even at 60 °C for 24 h. Phthalate dimer 5 is very highly growth inhibitory but not cytotoxic toward several human cancer cell lines; both dimers 5 and 7 very efficiently and selectively kill human cervical cancer cells in vitro in a dose-dependent manner with no cytotoxic effects on normal cervical cells.

Full text of DOI:10.1021/jm058288w

J. Med. Chem. 2006, 49, 2731-2734
2731
Second Generation, Orally Active, Antimalarial, Artemisinin-Derived Trioxane Dimers with
High Stability, Efficacy, and Anticancer Activity
†
‡
‡,§
†
†
|
Ik-Hyeon Paik, Suji Xie, Theresa A. Shapiro, Tanzina Labonte, Amy A. Narducci Sarjeant, Astrid C. Baege, and
Gary H. Posner*,
†,§
Department of Chemistry, School of Arts and Sciences, The Johns Hopkins UniVersity, 3400 North Charles Street, Baltimore, Maryland
2
1218-2685, DiVision of Clinical Pharmacology, Department of Medicine, School of Medicine, The Johns Hopkins UniVersity, Baltimore,
Maryland 21205, The Johns Hopkins Malaria Research Institute, Bloomberg School of Public Health, Baltimore, Maryland 21205, and
National Cancer Institute Center for Cancer Research, National Institutes of Health, Bethesda, Maryland 20892-5065
ReceiVed December 16, 2005
In only two steps and in 63% overall yield, naturally occurring 1,2,4-trioxane artemisinin (1) was converted
into C-10-carba trioxane conjugated diene dimer 4. This new dimer was then transformed easily in one
additional 4 + 2-cycloaddition step into phthalate dimer 5, and further modification led to bis-benzyl alcohol
dimer 7 and its phosphorylated analogues 8 and 9. Bis-benzyl alcohol dimer 7 is the most antimalarially
active in vitro, 10 times more potent than artemisinin (1). Bis-benzyl alcohol dimer 7 is approximately 1.5
times more orally efficacious in rodents than the antimalarial drug sodium artesunate and is about 37 times
more efficacious than sodium artesunate via subcutaneous administration. Both dimers 5 and 7 are thermally
stable neat even at 60 °C for 24 h. Phthalate dimer 5 is very highly growth inhibitory but not cytotoxic
toward several human cancer cell lines; both dimers 5 and 7 very efficiently and selectively kill human
cervical cancer cells in vitro in a dose-dependent manner with no cytotoxic effects on normal cervical cells.
Introduction
Results
Scheme 1 illustrates our two-step synthesis of trioxane dimer
conjugated diene 4 in overall 63% yield from artemisinin (1)
via formation of two new carbon-carbon bonds, using the linker
Some monomeric 1,2,4-trioxanes such as natural artemisinin
1
,2
(
1) have not only excellent antimalarial activities but also
3-6
significant anticancer activities. Recently, efforts to explore
the molecular mechanism of action of these monomeric 1,2,4-
trioxanes toward tumor cells have established a correlation
between a trioxane’s potency and mRNA gene expression, cell
2
2,23
2
,3-bis(trimethylsilylmethyl)-1,3-butadiene.
Our original
design of this diene dimer 4 was based on its anticipated ease
of preparation; an analogous successful double coupling of an
allylic bis-silane with dihydroartemisinin acetate (3) proceeds
doubling time, and the portion of cells in different cell cycle
1
8
phases.7,8 Also, the importance of transferrin9-11 for selective
smoothly. Diene dimer 4 was expected to be desirable due to
the well-known propensity of 1,3-dienes to enter easily into
cytotoxicity of monomeric 1,2,4-trioxanes toward cancer cells
2
4,25
was studied1
uptake by rapidly proliferating cancer cells
2,13
Diels-Alder cycloadditions
leading to rigid six-membered
to support the hypothesis that the higher iron
14,15
carbocycles. Being a conjugated diene, dimer 4 did indeed
undergo a 4 + 2 (Diels-Alder) cycloaddition with dimethyl
acetylenedicarboxylate followed by dichlorodicyanoquinone
is likely respon-
sible for the anticancer activity of trioxanes such as artemisinin.
Some dimeric trioxanes as well have very high anticancer
2
6
(
DDQ) oxidation to give phthalate dimer 5. Bis-ester 5 was
1
6-21
activities.
For example, three-carbon atom linked trioxane
hydrolyzed into phthalic acid 6 and separately was reduced into
bis-benzyl alcohol 7. Bis-benzyl alcohol 7 was phosphorylated
into bis-phosphate 8 and separately into cyclic phosphate 9
dimer alcohol 2 is almost as growth inhibitory toward aggressive
prostate cancer C2H cells as the clinically used anticancer agent
21
gemcitabine (Gemzar). We report here design, synthesis, and
preliminary biological evaluation of a new series of hydrolyti-
cally stable, C-10 nonacetal, four-carbon atom linked trioxane
dimers including phthalate 5 and its derivatives 6-9.
(Scheme 1). Importantly, none of these reactions destroyed the
crucial peroxide pharmacophore in trioxane dimers 5-9.
X-ray crystallography of crystalline phthalate diester 5 shows
that the two peroxide units in this trioxane dimer are oriented
in opposite directions. Whether this structural feature affects
the mechanism of action of this dimer remains to be determined.
All of the aromatic four-carbon linked dimers 5-9 are thermally
stable even upon accelerated aging in the absence of solvent at
6
0 °C for 24 h; less than 5% decomposition was observed by
1
H NMR spectroscopy. Of these new trioxane dimers, phthalic
acid 6 is by far the most soluble in aqueous pH 7.4 buffer
solution (≈14 mg/mL) at 25 °C. As C-10 nonacetal analogues
of artemisinin (1), all of these trioxane dimers 5-9 are
hydrolytically stable for at least 4 days in pH 7.4 buffer at 25
°
C.
*
Corresponding author: 410-516-4670 (phone). 410-516-8420 (fax).
Using our standard assay,27 we determined the antimalarial
ghp@jhu.edu (e-mail).
†
Department of Chemistry, The Johns Hopkins University.
Division of Clinical Pharmacology, The Johns Hopkins University.
The Johns Hopkins Malaria Research Institute.
National Cancer Institute Center for Cancer Research.
potencies of these dimers in vitro against chloroquine-sensitive
Plasmodium falciparum (NF 54) parasites (Table 1). Except for
water-soluble phthalic acid dimer 6, all of the other dimers in
‡
§
|
1
0.1021/jm058288w CCC: $33.50 © 2006 American Chemical Society
Published on Web 04/07/2006

2
732 Journal of Medicinal Chemistry, 2006, Vol. 49, No. 9
Paik et al.
Scheme 1
Table 1. Antimalarial Activities in Vitroa
7 stands out as the most potent, being approximately 10-times
more antimalarially active than artemisinin (1).
trioxane dimer
IC50 (nM)
As measured in mice according to a published protocol
involving single administration at a dose of 3, 10, or 30 mg/kg,
either subcutaneously (sc) or orally (po), bis-ester dimer 5 has
4
5
6
7
8
9
2.9
1.6
360
0.77
3.0
28
sc ED50 ) 0.71 mg/kg and diol dimer 7 has sc ED50 ) 0.06
mg/kg and po ED50 ) 2.6 mg/kg. Under these test conditions,
the clinically used monomeric trioxane sodium artesunate has
sc ED50 ) 2.2 mg/kg and po ED50 ) 4.0 mg/kg. Thus, these
two dimers 5 and 7 are approximately 3-37 times more
efficacious than the antimalarial drug sodium artesunate ad-
ministered sc, and diol dimer 7 is approximately 1.5 times more
efficacious than sodium artesunate administered po. Neither
overt toxicity nor behavioral modification was observed in the
mice due to drug administration.
3.7
6.6
artemisinin
a
The standard deviation for each set of quadruplicates was an average
of 7.8% (e18%) of the mean. R values for the fitted curves were g0.967.
Artemisinin activity is the mean ( standard deviation of the concurrent
control (n ) 6).
2
Table 1 are considerably more potent antimalarials than natural
artemisinin (1, IC50 ) 6.6 ( 0.76 nM). Bis-benzyl alcohol dimer
Preliminary growth inhibitory activities at nanomolar to
micromolar concentrations, measured in vitro as described
previously using a diverse panel of 60 human cancer cell lines
in the National Cancer Institute’s (NCI’s) Development and
2
9
Therapeutic Program showed phthalate dimer 5 to be ex-
tremely selective and highly potent at inhibiting the growth of
only nonsmall cell lung carcinoma HOP-92 cells, melanoma
SK-MEL-5 cells, and breast cancer BT-549 cells. Employing a
tetrazolium salt (XTT)-based calorimetric proliferation assay
(Roche Diagnostics, Mannheim, Germany) and using a modified
version of a recently reported protocol for in vitro evaluation
of the growth inhibitory activity of DHA toward the human
cervical cancer cell line HeLa (IC50 ) 5-10 µM),30 we have
found unexpectedly but importantly that trioxane phthalate dimer
5
(IC50 ) 500 nM) is approximately 10-20 times more potent
Figure 1. X-ray structure of phthalate dimer 5.
than trioxane monomer DHA and that trioxane diol dimer 7

Artemisinin-DeriVed Trioxane Dimers
IC50 ) 46.5 nM) is approximately 110-220 times more potent
than DHA, without being toxic to primary normal cervical cells.
Cell growth was inhibited in a dose-dependent manner.
In conclusion, new C-10 nonacetal trioxane dimers 5-9,
easily prepared in good overall yields in only three to five steps
from artemisinin, are stable and biological promising new
chemical entities. The most potent and selective two dimers in
this series, diester 5 and especially diol 7, deserve further
preclinical evaluation as potential drug candidates for effective
chemotherapy of malaria and cancer.31
Journal of Medicinal Chemistry, 2006, Vol. 49, No. 9 2733
(
consumption of starting material. Hydrochloric acid (0.3%) (10 mL)
and ethyl ether (10 mL) were added. Then, aqueous layer was
acidified with 10% hydrochloric acid (upon addition white pre-
cipitates were shown) and extracted with ethyl acetate (3 × 20 mL),
4
dried (MgSO ), and concentrated in vacuo. Flash column chroma-
tography on silica eluting with 40% ethyl acetate/hexanes (2% acetic
acid) to isolated bis-trioxane phthalic acid 6 as a white solid (3.8
1
mg, 5.2 µmol, 74%). mp ) 139-140 °C; H NMR (CDCl
3
, 400
MHz) δ 7.81 (s, 2H), 5.45 (s, 2H), 4.51-4.45 (m, 2H), 3.20-3.02
(m, 2H), 2.82-2.70 (m, 4H), 2.35-2.25 (m, 2H), 2.05-1.82 (m,
6H), 1.74-1.62 (m, 5H), 1.45-1.21 (m, 14H, including singlet at
1
.43), 1.00-0.81 (m, 14H, including two doublets at 1.00 (J ) 6.8
13
Hz) and 0.95 (J ) 6.0 Hz); C NMR (CDCl
3
, 100 MHz) δ 171.66,
Experimental Section
1
43.13, 131.85, 129.48, 103.42, 89.08, 80.91, 75.81, 52.22, 44.40,
Synthesis of Trioxane Butadiene Dimer 4. A solution of
dihydroartemisinin acetate (DHA acetate, 3) (835 mg, 2.56 mmol)
and the bis-silane butadiene linker (346 mg, 1.53 mmol, 0.6 equiv)
in dichloromethane (45 mL) was cooled to -78 °C. Tin(IV)
37.32, 36.51, 34.47, 30.71, 29.68, 25.68, 24.70, 20.17, 13.30; HRMS
(EI, m/z) for C H O Na calcd 7749.3507, found 749.3527; IR
4
0
54 12
-
1
(film, cm ) 3200(br), 2952, 2919, 2879, 1712, 1462, 1383, 1277,
1146, 1047, 994; [R]D2 ) 79.2 (CHCl , c ) 0.11).
4.4
3
tetrachloride (1 M solution in CH
equiv, diluted in 4 mL of dichloromethane and precooled to -78
C) was added quickly to the reaction mixture. The reaction was
2 2
Cl , 1.53 mL, 1.53 mmol, 0.6
Synthesis of Bis-benzylic Alcohol 7. A solution of bis-trioxane
phthalate bis-ester 5 (22.3 mg, 0.030 mmol) in dichloromethane
°
(
2.0 mL) was cooled to -78 °C. Diisobutyl aluminum hydride (1.5
stirred at -78 °C for a further 45 min at which time TLC analysis
confirmed complete consumption of starting material. Distilled
water (3 mL) was then added, and the reaction was allowed to warm
to room temperature. Distilled water (10 mL) and dichloromethane
M solution in CH Cl2, 0.2 mL, 0.30 mmol, 10 equiv) was added
2
slowly dropwise to the reaction mixture. The reaction was stirred
at -78 °C for further 30 min at which time TLC analysis confirmed
complete consumption of starting material. Distilled water (0.5 mL)
was then added, and the reaction was allowed to warm to room
temperature. Distilled water (5 mL) and dichloromethane (15 mL)
were added, and organics were extracted with dichloromethane (2
(30 mL) were added, and organics were extracted with dichlo-
romethane (3 × 20 mL), dried (MgSO
4
), and concentrated in vacuo
to give a yellow solid. Gradient column chromatography on silica
eluting with 5-10% ethyl acetate/hexanes isolated trioxane buta-
diene dimer 4 as a white solid (541 mg, 0.88 mmol, 69%). Mp )
×
20 mL), dried (MgSO
yellow oil. Gradient column chromatography on silica eluting with
0-80% ethyl acetate/hexanes isolated bis-trioxane bis-benzyl
4
) and concentrated in vacuo to give a
1
6
2
(
8-72 °C; H NMR (400 MHz, CDCl
3
) δ 5.35 (s, 2H), 5.19 (s,
7
H), 5.16 (s, 2H), 4.48 (ddd, J ) 9.6, 6.0, 3.2 Hz, 2H), 2.73-2.63
alcohol 7 as a white solid (13.2 mg, 0.019 mmol, 64%). Mp )
m, 2H), 2.55-2.26 (m, 6H), 2.06-1.96 (m, 2H), 1.95-1.86 (m,
H), 1.86-1.77 (m, 2H), 1.69-1.58 (m, 4H), 1.52-1.20 (m, 14H
including singlet at 1.39), 0.96 (d, J ) 6.0 Hz, 6H), 0.91 (d, J )
1
1
2
28-130 °C; H NMR (CDCl
3
, 400 MHz) δ 7.24 (s, 2H), 5.43 (s,
2
H), 4.64 (s, br, 4H), 4.49-4.41 (m, 2H), 3.22 (s, br, 2H), 2.95
(
dd, J ) 15.2, 10.0 Hz, 2H), 2.80-2.68 (m, 4H), 2.35-2.25 (m,
H), 2.05-1.61 (m, 11H), 1.45-1.21 (m, 13H, including singlet
at 1.32), 1.00-0.81 (m, 14H, including apparent triplet at 0.98
7
1
3
.2 Hz, 6H), 0.98-0.86 (m, 2H); 13C NMR (100 MHz, CDCl
3
) δ
2
45.07, 113.58, 103.00, 89.16, 81.05, 72.74, 52.23, 44.36, 37.45,
6.64, 34.44, 33.79, 30.46, 25.98, 24.85, 24.73, 20.15, 13.00; IR
13
(
1
3
J ) 8.4 Hz); C NMR (100 MHz, CDCl
3
) δ 138.68, 137.17,
31.12, 103.24, 89.05, 81.01, 76.12, 63.99, 52.28, 44.47, 37.43,
6.58, 34.48, 31.96, 30.74, 25.89, 24.80, 24.71, 20.20, 13.32; HRMS
10Na calcd 721.3922, found 721.3917; IR
(film, cm ) 3401, 2949, 2875, 1454, 1377, 1205, 1188, 1124, 1090,
-
1
(
film, cm ) 2991, 2950, 2909, 2854, 1366, 1085, 1044, 872, 729;
HRMS(ES) m/z calcd for C36 Na (M + Na) 637.3711, found
, c ) 0.28).
Synthesis of Phthalate Dimer 5. To a solution of trioxane
butadiene dimer 4 (235 mg, 0.382 mmol) in anhydrous benzene
12.0 mL) was added dimethylacetylene dicarboxylate (0.094 mL,
54 8
H O
65.9 (CHCl
3
23.6
6
37.3683; [R]
D
(
58
EI, m/z) for C40H O
-1
23.5
1042, 1013, 941, 877, 825, 735; [R]
D
) 63.7 (CHCl , c ) 0.10).
3
(
Synthesis of Bis-trioxane Bis-ethyl Phosphate 8. To a solution
of bis-trioxane bis-benzyl alcohol 7 (20.0 mg, 0.029 mmol) in
anhydrous dichloromethane (2.0 mL) were added pyridine (0.012
mL, 0.143 mmol, 5.0 equiv) and diethyl chlorophosphate (0.020
mL, 0.143 mmol, 5.0 equiv) at 0 °C. The reaction mixture was
stirred for 30 min at 0 °C and slowly warmed to room temperature
for 1 h, at which time TLC analysis showed full consumption of
starting material. Brine (5 mL) and dichloromethane (10 mL) were
added and organics were extracted with dichloromethane (2 × 20
0
8
.764 mmol, 2.0 equiv). Then, the reaction mixture was heated to
0-85 °C for 18 h, at which time TLC analysis showed full
consumption of starting material. The reaction mixture was cooled
to room temperature and treated with dichlorodicyanoquinone
(
DDQ) (43.4 mg, 0.191 mmol, 0.5 equiv) and heated to 80-85 °C
for 20 min. Brine (15 mL) and ethyl ether (30 mL) were added,
and organics were extracted with ethyl ether (3 × 30 mL), dried
4
(MgSO ) and concentrated in vacuo to give a yellow sticky solid.
Gradient column chromatography on silica eluting with 20-30%
ethyl acetate/hexanes isolated bis-trioxane 5 as a white solid (157
mL), dried (MgSO ), and concentrated in vacuo to give a sticky
4
solid. Flash column chromatography on silica eluting with 2%
1
mg, 0.208 mmol, 54%). Mp ) 108-111 °C; H NMR (CDCl
3
,
methanol/dichloromethane isolated bis-trioxane bis-phosphate 8 as
1
4
00 MHz) δ 7.62 (s, 2H), 5.40 (s, 2H), 4.56-4.49 (m, 2H), 3.85
s, 6H), 3.10 (dd, J ) 14.8, 9.6 Hz, 2H), 2.82-2.70 (m, 4H), 2.35-
.25 (m, 2H), 2.05-1.82 (m, 6H), 1.74-1.62 (m, 5H), 1.45-1.21
m, 13H, including singlet at 1.29), 1.00-0.81 (m, 14H, including
two doublets at 1.00 (J ) 7.6 Hz) and 0.97 (J ) 6.4 Hz); C NMR
CDCl , 100 MHz) δ 168.39, 142.99, 129.95, 129.48, 103.10, 89.17,
1.01, 75.47, 52.41, 52.16, 44.30, 37.45, 36.57, 34.46, 32.83, 30.81,
5.78, 24.75, 20.16, 13.16; HRMS (EI, m/z) for C42 12Na calcd
77.3820, found 777.3824; IR (film, cm ) 2932, 2866, 1726, 1443,
a white foam (14.4 mg, 0.015 mmol, 52%). H NMR (CDCl , 400
3
(
2
MHz) δ 7.28 (s, 2H), 5.43 (s, 2H), 5.12 (d, J ) 7.6 Hz, 4H), 4.41-
4.36 (m, 2H), 4.12-4.00 (m, 8H), 3.06 (dd, J ) 15.2, 9.6 Hz, 2H),
2.81-2.70 (m, 4H), 2.38-2.25 (m, 2 H), 2.01-1.85 (m, 6H), 1.73-
1.60 (m, 4H), 1.53-1.19 (m, 26H, including singlet at 1.30), 1.00-
0.81 (m, 14H, including doublet at 0.99 (J ) 7.6 Hz) and doublet
(
13
(
3
at 0.97 (J ) 6.4 Hz); 13C NMR (CDCl , 100 MHz) δ 140.16,
8
2
7
1
0
3
58
H O
132.09, 132.02, 131.16, 103.18, 88.84, 80.99, 66.52, 66.47, 63.80,
63.75, 52.32, 44.56, 37.38, 36.58, 34.51, 32.35, 30.72, 25.96, 24.71,
20.20, 16.14, 16.07, 13.45; HRMS (EI, m/z) for C H O P Na
-
1
2
4.5
389, 1284, 1238, 1120, 1054, 988; [R]
D
) 112.8 (CHCl , c )
3
4
8
76 16 2
-
1
.51).
requires 993.4501, found 993.4503l; IR (film, cm ) 2965, 2932,
24.6
Synthesis of Bis-acid 6. Bis-trioxane phthalate bis-ester 5 (5.3
2879, 2860, 1390, 1271, 1027, 974; [R]
D
) 96.1 (CHCl , c )
3
mg, 7.0 µmol) was dissolved in tetrahydrofuran (0.7 mL) and
distilled water (0.3 mL) and treated with lithium hydroxide
monohydrate (5.9 mg, 0.14 mmol, 20 equiv). The reaction mixture
was stirred for 18 h, at which time TLC analysis showed full
0.04).
Synthesis of Bis-trioxane Cyclic Phosphate 9. To a solution
of bis-trioxane bis-benzyl alcohol 7 (20.0 mg, 0.029 mmol) in
anhydrous dichloromethane (2.0 mL) were added pyridine (0.010

2
734 Journal of Medicinal Chemistry, 2006, Vol. 49, No. 9
Paik et al.
mL, 0.129 mmol, 4.5 equiv) and phenyl dichlorophosphate (0.013
mL, 0.086 mmol, 3.0 equiv) at room temperature. The reaction
mixture was stirred for 18 h, at which time TLC analysis showed
full consumption of starting material. Brine (5 mL) and dichlo-
romethane (10 mL) were added, and organics were extracted with
(11) Beyer, U.; Roth, T.; Schumacher, P.; Maier, G.; Unold, A.; Frahm,
A. W.; Fiebig, H. H.; Unger, C.; Kratz, F. Synthesis and in Vitro
Efficacy of Transferrin Conjugates of the Anticancer Drug Chloram-
bucil. J. Med. Chem. 1998, 41, 2701-2708.
(
12) Singh, N. P.; Lai, H. Selective toxicity of dihydroartemisinin and
holotransferrin toward human breast cancer cells. Life Sci. 2001, 70,
49-56.
dichloromethane (2 × 20 mL), dried (MgSO
4
), and concentrated
in vacuo to give a sticky solid. Flash column chromatography on
silica eluting with 40% ethyl acetate/hexanes isolated bis-trioxane
(13) Lai, H.; Sasaki, T.; Singh, N. P.; Messay, A. Effects of artemisinin-
tagged holotransferrin on cancer cells. Life Sci. 2005, 76, 1267-
1279.
cyclicphosphate 9 as a white solid (11.2 mg, 0.013 mmol, 47%).
1
(14) Ikuta, K.; Fujimoto, Y.; Suzuki, Y.; Tanaka, K.; Saito, H.; Ohhira,
M.; Sasaki, K.; Kohgo, Y. Overexpression of Hemochromatosis
Protein, HFE, Alters Transferrin Recycling Process in Human
Hepatoma Cells. Biochim. Biophys. Acta 2000, 1496, 221-223.
(15) Kawabata, H.; Nakamaki, T.; Ikonomi, P.; Smith, R. D.; Germain,
R. S.; Koeffler, H. P. Expression of Transferrin Receptor 2 in Normal
and Neoplastic Hematopoietic Cells. Blood 2001, 98, 2714-2719.
(16) Woerdenbag, H. J.; Moskal, T. A.; Pras, N.; Malingre, T. M.; Elferaly,
F. S.; Kampinga, H. H.; Konings, A. W. T. Cytotoxicity of
Artemisinin-Related Endoperoxides to Ehrlich Ascites Tumor-Cells.
J. Nat. Prod. 1993, 56, 849-856.
Mp ) 130-133 °C; H NMR (CDCl
3
, 400 MHz) δ 7.38-7.32
(
m, 3H), 7.30-7.25 (m, 2H), 7.22-7.15 (m, 1H), 5.42 (s, 1H),
5
(
.41 (s, 1H), 5.38-5.27 (m, 2H), 5.22-5.11 (m, 2H), 4.60-4.55
m, 1H), 4.51-4.47 (m, 1H), 2.98-2.91 (m, 2H), 2.79-2.69 (m,
4
1
0
1
1
4
3
2
8
1
2
H), 2.36-2.26 (m, 2H), 2.05-1.81(m, 6H), 1.71-1.60 (m, 6H),
.45-1.20 (m, 13H, including singlets at 1.31 and 1.30), 1.00-
.81 (m, 14H); 1 C NMR (CDCl
3
3
, 100 MHz) δ 140.09, 140.05,
32.61, 132.47, 130.54, 130.12, 129.82, 125.09, 119.80, 119.75,
03.08, 102.99, 89.45, 89.22, 81.01, 75.26, 74.81, 69.16 (d, J )
.5 Hz), 69.09 (d, J ) 4.5 Hz), 52.19, 52.10, 44.29, 44.19, 37.45,
6.57, 34.41, 32.23, 32.06, 30.84, 25.91, 24.82, 24.76, 24.73, 20.15,
0.13, 13.10, 12.97; HRMS (EI, m/z) for C46
59.3793, found 859.3793; IR (film, cm ) 2929, 2881, 1498, 1444,
(
17) Posner, G. H.; Ploypradith, P.; Parker, M. H.; O’Dowd, H.; Woo, S.
H.; Northrop, J.; Krasavin, M.; Dolan, P.; Kensler, T. W.; Xie, S. J.;
Shapiro, T. A. Antimalarial, antiproliferative, and antitumor activities
of artemisinin-derived, chemically robust, trioxane dimers. J. Med.
Chem. 1999, 42, 4275-4280.
61
H O10PNa calcd
-
1
24.1
389, 1295, 1193, 1125, 1085, 1017, 1010, 935, 738; [R]
8.6 (CHCl , c ) 0.45).
D
)
(
18) Posner, G. H.; Paik, I.-H.; Sur, S.; McRiner, A. J.; Borstnik, K.; Xie,
S.; Shapiro, T. A. Orally Active, Antimalarial, Anticancer, Artemisi-
nin-Derived Trioxane Dimers with High Stability and Efficacy. J.
Med. Chem. 2003, 46, 1060-1065.
3
Acknowledgment. We thank the NIH (AI34885 and
RR00052) for financial support and Dr. Reto Brun and Dr.
Sergio Wittlin (Swiss Tropical Institute) for the in vivo
antimalarial testing. This research was in part supported by the
Intramural Research Program of the NIH, National Cancer
Institute, Center for Cancer Research.
(19) Jung, M.; Lee, S.; Ham, J.; Lee, K.; Kim, H.; Kim, S. K. Antitumor
activity of novel deoxoartemisinin monomers, dimers, and trimer. J.
Med. Chem. 2003, 46, 987-994.
(
20) Jeyadevan, J. P.; Bray, P. G.; Chadwick, J.; Mercer, A. E.; Byrne,
A.; Ward, S. A.; Park, B. K.; Williams, D. P.; Cosstick, R.; Davies,
J.; Higson, A. P.; Irving, E.; Posner, G. H.; O’Neill, P. M.
Antimalarial and antitumor evaluation of novel C-10 nonacetal dimers
of 10 beta-(2-hydroxyethyl)deoxoartemisinin. J. Med. Chem. 2004,
47, 1290-1298.
Supporting Information Available: X-ray crystallographic data
1
13
for compound 5. H and C NMR spectra of compounds 5 and 7.
This material is available free of charge via the Internet at http://
pubs.acs.org.
(
21) Posner, G. H.; McRiner, A. J.; Paik, I.-H.; Sur, S.; Borstnik, K.; Xie,
S.; Shapiro, T. A. Anticancer and Antimalarial Efficacy and Safety
of Artemisinin-Derived Trioxane Dimers in Rodents. J. Med. Chem.
2
004, 47, 1299-1301.
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