Synthesis of 17β-estradiol-platinum(II) hybrid molecules showing cytotoxic activity on breast cancer cell lines

Article abstract of DOI:10.1016/j.bmcl.2008.03.005

The synthesis of a series of 17β-estradiol-platinum(II) hybrid molecules is reported. The hybrids are made of a PEG linking chain of various length and a 2-(2′-aminoethyl)pyridine ligand. They are prepared from estrone in five chemical steps with an overall yield of 22%. The length of the PEG chain does not influence the solubility of the compounds as it remains relatively constant throughout the series. MTT assays showed that the derivative with the longest PEG chain showed the best activity against breast cancer cell lines (MCF-7 and MDA-MB-231). Molecular modeling study rationalized the results.

Full text of DOI:10.1016/j.bmcl.2008.03.005

Available online at www.sciencedirect.com
Bioorganic & Medicinal Chemistry Letters 18 (2008) 2282–2287
Synthesis of 17b-estradiol-platinum(II) hybrid molecules
showing cytotoxic activity on breast cancer cell lines
a
a
b,c
Jos e´ e Provencher-Mandeville, Caroline Desc oˆ teaux, Sanat K. Mandal,
a
a
a,
*
´
Val e´ rie Leblanc, Eric Asselin and Gervais B e´ rub e´
a
D e´ partement de Chimie-Biologie, Groupe de Recherche en Biopathologies Cellulaires et Mol e´ culaires, Universit e´ du Qu e´ bec a`
Trois-Rivi e` res, C.P. 500, Trois-Rivi e` res, Que., Canada G9A 5H7
b
Division of BioMedical Sciences, Faculty of Medicine, Memorial University, St. John’s, Nfld, Canada A1B 3V6
Division of Science & Technology, College of the North Atlantic, Clarenville Campus, Clarenville, Nfld, Canada A5A 1V9
c
Received 18 January 2008; revised 29 February 2008; accepted 3 March 2008
Available online 6 March 2008
Abstract—The synthesis of a series of 17b-estradiol-platinum(II) hybrid molecules is reported. The hybrids are made of a PEG link-
ing chain of various length and a 2-(2 -aminoethyl)pyridine ligand. They are prepared from estrone in five chemical steps with an
0
overall yield of 22%. The length of the PEG chain does not influence the solubility of the compounds as it remains relatively constant
throughout the series. MTT assays showed that the derivative with the longest PEG chain showed the best activity against breast
cancer cell lines (MCF-7 and MDA-MB-231). Molecular modeling study rationalized the results.
ꢀ
2008 Elsevier Ltd. All rights reserved.
Platinum(II)-based anticancer therapies remain, to this
day, a useful and effective methodology for the manage-
toward cancer cells which lead to severe toxic side ef-
6
fects, primarily kidney toxicity and neurotoxicity.
,7
1
,2
ment of several types of cancers. Even if much work
has been done in order to improve the platinum(II) anti-
cancer drugs, only a few selected compounds are used
today in clinics. They are cisplatin (cis-diamminedichlo-
roplatinum(II)) and carboplatin (diamine[1,1-cyclob-
Recent literature reviews present a broad overview of
the actual knowledge of platinum-based antitumor
3
–5,8
agents as well as their action mechanisms.
The anti-
tumor activity of platinum drugs is a consequence of
their interaction with DNA. Cisplatin binds readily to
the N7 position of the guanine bases of DNA molecules
thereby blocking replication and/or transcription, and
0
utanedicarboxylato]-O,O -platinum(II)), the first and
second platinum(II) derivatives to hit the market, and
more recently oxaliplatin, nedaplatin, iobaplatin, and
3
–5
4–6
heptaplatin (SK12053R). The first three platinum(II)
complexes are used worldwide but the last three are used
regionally, primarily in Asian countries. The platinum
complexes have been mainly used for the treatment of
solid tumors, particularly small cell lung, ovarian, testic-
ular, head, and neck tumors. The specific uses of these
drugs vary from one to another. However, oxaliplatin,
nedaplatin, iobaplatin and heptaplatin have not shown
any distinct and overwhelming advantages over cisplatin
ultimately inducing apoptosis.
Several research groups, including ours, have been
investigating the combination of a platinum complex
to an estrogenic moiety in order to target the estrogen
receptor (ER) in hormone-dependent diseases, particu-
9
larly breast cancer. Manifestly, the overall goal is to im-
prove the selectivity and efficacy of this type of drug
and, more importantly, to minimize its toxic side effects.
A recent review has recently presented various preclini-
cal and clinical studies on the use of platinum complexes
3
–5
and carboplatin. In general, the platinum-based drugs
suffer from two main disadvantages: chemoresistance to
4
9
the drugs can occur and second they are non selective
for breast cancer treatment.
Thus, the estrogen receptor is a biological target that has
attracted considerable attention over the years. It is ex-
Keywords: Estradiol-platinum(II) complexes; Breast cancer; Estrogen
receptor; Molecular modeling.
1
0
pressed by several types of cancers; breast (60–70%),
1
uterus (70–73%) as well as ovarian (61%). Together,
1
12
*
Corresponding author. E-mail: Gervais.Berube@uqtr.ca
0
960-894X/$ - see front matter ꢀ 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2008.03.005

J. Provencher-Mandeville et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2282–2287
2283
they represent 40% of all cancers diagnosed in women
Table 1. Calculated logP of the aminopyridine ligands 4a–e, of the
final E -Pt(II) hybrids 1a–e and of 17b-estradiol
1
3
and display a 25% mortality rate. The biological affin-
ity between 17b-estradiol and its cognate receptor can
theoretically be used to direct a cytotoxic agent to the
target cells.
2
a
b
a
b
Compound
clogP
Compound
clogP
4
4
4
a
b
c
3.98
3.81
3.64
3.48
3.32
1a
1b
1c
1d
1e
4.40
4.24
4.07
3.91
3.74
This manuscript describes the straightforward synthesis
4d
4e
of a new family of 17b-estradiol-platinum(II) (E -Pt(II))
2
c
hybrid molecules 1 (Scheme 1). The novel platinum
complexes are linked with a polyethylene glycol (PEG)
chain at position 16a of the steroid nucleus and bear a
17b-Estradiol
4.00
a
b
c
Chain length: a (n = 1), b (n = 2), c (n = 3), d (n = 4), and e (n = 5).
Calculated logP as obtained with CaChe work system pro, 2006.
20
1
6b-hydroxymethyl side chain. They are made from es-
Reported literature value for 17b-estradiol is 3.90.
trone in only five chemical steps with an overall yield
of 22%. The PEG-chain was used in order to obtain
compounds with relatively constant solubility through-
out the series and to study more accurately the true
influence of the length of the chain on the biological
activity. This class of compounds completes our previ-
ous work done on similar derivatives; see compound 2
brids 1a–e should also possess relatively constant
solubility. The clogP of the final platinum(II) complexes
vary from 4.40 for 1a to 3.74 for 1e. Thus, a slight in-
crease of solubility is predicted for derivatives 1 as the
chain is lengthening. Consequently, we speculated that
the difference in cytotoxicity, if any, should only
reflect the influence of the length of the PEG tether
chain on the final hybrid molecules.
1
4–17
and 3, which used a carbon chain tether (Scheme 1).
The objective of the present study was also to determine
the cytotoxic effect of these novel molecules using estro-
gen dependent (estrogen receptor positive; ER ) and
+
ꢀ
independent (estrogen receptor negative; ER ) human
breast cancer cells. The biological activity of these com-
pounds was evaluated in vitro using an MTT cell prolif-
OH
OH
NH
N
O
n
1
8,19
eration assay.
The MTT assay was performed over
HO
an incubation period of 72 h. The affinity for the estro-
gen receptor alpha (ERa) was also determined for deriv-
ative 1b.
4
The synthesis involves only five chemical steps starting
from estrone as the steroid template. The 17b-estra-
diol-Pt(II) complexes 1a–e were obtained efficiently in
high yield (22% overall) using an efficient reaction
sequence.
As anticipated, the calculated logP of the aminopyridine
ligands 4a–e is relatively constant throughout the series
varying from 3.98 for 4a to 3.32 for 4e (Table 1). Estra-
diol itself has a clogP of 4.00. The final E -Pt(II) hy-
2
First, the preparation of the PEG chains was accom-
plished from commercially available 2-chloroethyl ether
(5) and from PEG of various lengths (6b–e) (Scheme 2).
Thus, treatment of 2-chloroethyl ether with sodium io-
dide in refluxing acetone for 3 days gave 2-iodoethyl
ether (7a) in 81% yield. Derivatives 7b–e were obtained
in a two-step reaction sequence. The PEG chains were
treated with mesyl chloride and triethylamine in diethyl
ether at 0 ꢁC to give the bis-mesylate intermediates 8b–e.
The bis-mesylates 8a–e were subsequently treated, with-
OH
OH
NH
N
O
Pt
Cl Cl
n
HO
1
OH
2
OH
NH N
Pt
Cl Cl
p
HO
Cl
NaI, acetone
reflux, (81%)
I
O
O
Cl
I
5
7a
OH
OH MsCl, Et N
3
p
NH
OMs
O
H
O
HO
n
o
n
Cl Pt
Cl
MsO
Et2O, 0 C, N2
N
6
b-e
8b-e
HO
3
NaI, acetone
reflux, (79%)
I
p = 2 to 12 carbon atoms
n = 1(a), 2(b), 3(c), 4(d) or 5(e)
O
I
n
7
b-e
Scheme 1. Structure of the 17b-estradiol-platinum(II) complexes
studied in our laboratory.
Scheme 2. Preparation of bis-diodo-PEG chains 7a–e.

2284
J. Provencher-Mandeville et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2282–2287
2
1
out purification, with excess sodium iodide in refluxing
acetone to give the diiodo-PEG chains 7b–e in 79% aver-
age yield.
presence of pyridinium p-toluenesulfonate. The yield
of the protection reaction is 99%. The intermediate
was further transformed into the b-keto-ester 10 upon
treatment with dimethyl carbonate in the presence of
2
2,23
As shown in Scheme 3, estrone (9) was initially pro-
tected as a tetrahydropyranyl ether (R = THP) under
standard reaction conditions. Accordingly, estrone was
treated with dihydropyran in dichloromethane in the
KH in dry tetrahydrofuran.
Derivative 10 was ob-
tained with 90% yield. Treatment of derivative 10 with
a suitable diiodo-PEG chains 7a–e and with cesium car-
bonate in tetrahydrofuran gave compounds 11a–e in
6
3% yield. The iodo-PEG chain was added to the less
hindered a face of the molecule as shown by the pres-
ence of a single peak for the 18-CH at d 0.90 in the
3
O
1
13
H NMR spectrum and at d 14.2 ppm in the
C
NMR spectrum. Reduction of the b-keto-ester moiety
with lithium borohydride in dry ether at 0 ꢁC followed
by the cleavage of the tetrahydropyranyl ether gave
1
4,21
the triol 12a–e.
It was obtained in 70% overall yield
9
HO
as a single 17b-hydroxy isomer as shown by a sole signal
1
for the 18-CH at d 0.88 in the H NMR spectrum and
3
1
3
at d 12.5 ppm in the C NMR spectrum. The stereo-
chemistry of the 17b-hydroxy function was confirmed
by comparison with C NMR spectral data of known
a
1
3
O
24
1
7b- and 17a-estradiol derivatives.
O
OCH3
The final 17b-estradiol-linked Pt(II) complexes 1a–e
were obtained in a two-step chemical sequence. First,
H
14
the triol 12a–e was treated with excess 2-aminoalkylpyri-
dine to give derivatives 4a–e for a yield of 80–100%. It is
noteworthy that a short reaction period is necessary for
this reaction in order to avoid the decomposition of the
PEG tether chain. Thus, this reaction is performed in
only 4 h instead of about 20 h when a, x-dibromoalkane
1
0
THPO
b
O
O
1
4,16
chain is used.
Second, the triol-aminopyridine inter-
OCH3
O
mediates 4a–e were treated with potassium tetrachloro-
platinate in a mixture of dimethylformamide and
water to give the corresponding 17b-estradiol-PEG-
linked Pt(II) complexes 1a–e with n = 1, 2, 3, 4, and 5.
The yield of this two-step sequence was 55%. As a result,
the new cytotoxic molecules possess a PEG tether chain
varying from 5 to 17 atoms long. All new compounds
synthesized were characterized by IR, NMR spectros-
n
I
THPO
1
1a-e
c
2
5
OH
copy, and mass spectrometry.
OH
O
As shown by the MTT assays, the new Pt(II) complexes
present no specific toxicity toward ER breast cancer
+
n
I
cells (Table 2). However, it is important to indicate that
the desired selectivity toward ER cancer cells might be
+
HO
1
2a-e
d
a
Table 2. Inhibitory concentration of cisplatin and 1a–e on both ER
+
ꢀ
and ER breast cancer cell lines
OH
+
MCF-7 (ER )
Compounds
MDA-MB-231
ꢀ
Chain length
OH
(
ER )
a
H
a
O
IC50 (lM)
IC50 (lM)
n
n
N
Cisplatin
18.97 ± 0.43
68.50 ± 3.01
33.44 ± 1.79
38.04 ± 2.02
35.64 ± 0.84
20.61 ± 0.94
17.33 ± 2.28
38.67 ± 4.15
17.86 ± 1.33
27.29 ± 4.61
17.52 ± 1.47
13.90 ± 1.87
—
1
Cl Pt
Cl
HO
1a
1b
N
2
1
a-e
1
1
1
c
d
e
3
4
Scheme 3. Synthesis of 17b-estradiol-linked platinum(II) complexes.
Reagents and conditions: (a) 1—DHP, PPTs, CH Cl
, 22 ꢁC, 24 h; 2—
KH, dimethyl carbonate, THF, reflux, 3 h, 90%; (b) 7a–e, Cs CO
THF, reflux, 4 h, 63%; (c) 1—LiBH , Et
O, 0 ꢁC, 1 h and 22 ꢁC, 11 h;
—PPTs, EtOH, 22 ꢁC, 4 h, 70%; (d) 1—2-(2 -aminoethyl)pyridine,
CH OH, reflux, 4 h; 2—K PtCl , DMF/H
O (2:1), 22 ꢁC, 2 days, 55%.
5
2
2
a
Inhibitory concentration (IC50, lM) as obtained by the MTT assay.
Experiments were performed in duplicates and the results represent
means ± SEM of three independent experiments. The cells were
incubated for a period of 72 h.
2
3
,
4
2
0
2
3
2
4
2

J. Provencher-Mandeville et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2282–2287
2285
expressed more clearly (and possibly only) in vivo as it
was previously demonstrated for similar types of deriv-
As mentioned earlier, the new estrogen-PEG-Pt(II) hy-
brid molecules 1a–e are relatively less potent than the
previous analogous platinum complexes linked with an
alkyl chain (see structure 2). To understand the differ-
ences in potency between these two series, we performed
molecular modeling and docking experiments using the
optimized structures of these classes of compounds
and the crystal structure of estrogen receptor alpha
(ERa). Thus, we superimposed two of the most active
compounds from each class (Fig. 2). Figure 2 shows that
2
6,27
atives.
1
A typical dose–response curve for derivative
e is shown in Figure 1.
0
The estrogen-PEG-Pt(II) hybrid molecules carry a 2-(2 -
aminoethyl)pyridine ligand which was found to be the
best ligand for biological activity for hybrids of formu-
lae 2 and 3. However, hybrids 1a–e were generally less
cytotoxic than cisplatin itself. The length of the side
chain seems to be optimal at n = 5 where we observed
an IC50 of 20.6 and 13.9 lM, respectively, for the
MCF-7 and MDA-MB-231 cancer cells. The derivative
with shorter side chains (n = 1) is the least active estra-
diol-PEG-hybrid of the series. Moreover, it is observed
that the cytocidal activity is generally more important
on the hormone-independent breast cancer cells. If selec-
tivity can be achieved in animal models, derivative 1e
might become an alternative of choice for site-specific
treatment of hormone-dependent breast cancer.
the orientation of the reactive site, PtCl portion, is sig-
2
nificantly different between the two compounds (1e and
CD-38 (compound 2, p = 8)) despite their significant pla-
narity between the estradiol moieties. Similar differences
were observed when these two compounds were docked
to the active site of the ERa (Figs. 3 and 4). According
to 3D model based on X-ray structure of 17b-estradiol
bound to the estrogen receptor, the OH group at posi-
tion 3 (steroid numbering) of all compounds form three
hydrogen bonds with proteins, ARG 394 and GLU 353
and the other with a second hydroxyl group of the estra-
The estrogen receptor alpha (ERa) affinity assay was
performed using the HitHunter EFC Estrogen Fluo-
TM
rescence assay kit (Discoverx, Fremont, CA) according
2
to the manufacturer’s instructions.
8
The estrogen receptor binding studies showed good
affinity for derivative 1b to the estrogen receptor alpha.
The reference derivative, that is, cisplatin present, as ex-
pected, no affinity for the ERa. The estrogen-PEG-
Pt(II) hybrid molecule 1b has an EC50 of 4.25 nM com-
pared to 0.66 nM for 17b-estradiol, the natural ligand.
This type of molecule presents lower affinity than the
previous class of derivatives 2 and 3 reported earlier.
Molecular modeling: All calculations (molecular
mechanics, MM2) and modeling were performed on
2
9
CACheWorkSystem Pro. In order to better under-
stand the biological activity of these molecules they were
docked into the active site of the estrogen receptor (PDB
Figure 2. Superimposition of the most stable conformation of com-
pounds 1e (purple) and CD-38 (blue) showing the difference between
the two compounds.
3
0
1
ERE).
MTT assay, 72h
1
1
25
00
MCF-7
MDA-MB-231
75
50
25
0
0
10 20 30 40 50 60 70 80
Doses (uM)
˚
Figure 3. Docking view of compound 1e to the active site (within 3 A)
of ERa (PDB, Code: 1ERE). All Hydrogen bond are shown using blue
arrows and labels. Yellow labels indicate atoms that are too close
Figure 1. Typical dose–response curves for E
2
-PEG-Pt(II) complex 1e
as obtained by the MTT assay for 72 h treatment.
2
together. The PtCl moiety is pointing toward the active site.

2286
J. Provencher-Mandeville et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2282–2287
We also examined the quantitative structure–activity
relationship between IC50 and the solvent accessible sur-
face area, a known molecular descriptor. The surface
area of the electron density isosurface is determined
after optimizing the molecular geometry using MOPAC
with PM5 parameters. Figure 5 shows the plots of sol-
vent accessible surface area versus IC . A linear rela-
5
0
tionship between this molecular descriptor and IC5
was observed. The value of correlation coefficient (r )
0
2
between solvent accessible surface area and IC50 is
0
.730 for MCF-7 and 0.64 for MDA-MB-231 cell lines,
respectively. As shown in Figure 5, the potency is great-
er for larger value of solvent accessible surface area.
In summary, this manuscript presents a new series of
cytotoxic 17b-estradiol-PEG-linked Pt(II) hybrid mole-
cules (1a–e). They are readily available from estrone in
only five chemical steps with excellent yields (22%
overall). The biological activity is lower than that of
the hybrids of first and second family, see derivatives
Figure 4. Docking view of compound CD-38 to the active site (within
˚
3
A) of ERa (PDB, Code: 1ERE). All Hydrogen bond are shown using
blue arrows and labels. Yellow labels indicate atoms that are too close
together. The PtCl core is oriented outward of the active site.
2
and 3. The most promising compound of the series
2
is derivative 1e, which is equipotent to cisplatin itself.
Despite a relatively low cytocidal activity, the novel
hybrids could have interesting in vivo biological po-
tential due to their enhanced solubility as compared
to the first two prototypes (2 and 3). Molecular mod-
eling studies show that the orientation of the platinum
diol moiety (blue labels in Figs. 3 and 4). Both classes of
compounds have very similar bonding interactions with
the active site of ERa but the orientation of the plati-
num moiety is quite different between the two com-
pounds (Figs. 3 and 4). In PEG derivative, the PtCl2
moiety is oriented toward the ERa and may not be
freely available for further interaction with its targets.
core is different when the E -PEG-Pt(II) hybrid is
2
compared to the best of the platinum complexes of
family 2 (CD-38 (2, p = 8)), which bears a 10 carbon
atoms alkyl chain. However, we show that the plati-
num core is outside the ERa pocket for the novel
However, the PtCl is oriented outside the ERa pocket
2
and the reactive site (PtCl ) maybe readily available
2
for its targets. Despite the extra hydrogen bond between
PHE 425 and 1e (Fig. 3), CD-38 is the most potent E2-
Pt(II) hybrid. Therefore, the orientation of the reactive
site is an important factor for biological activity.
E -PEG-Pt(II) hybrid 1e, which could account for its
2
cytocidal activity. Further biological investigation of
this type of compounds is warranted and is in progress
in our laboratory.
Figure 5. Regression analysis showing the relationship between the surface area and the IC50 values of MCF-7 cells (black circles on the line,
2
2
r = 0.73) and for MDA-MB-231cells (green rectangles and line, r = 0.65).

J. Provencher-Mandeville et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2282–2287
2287
Acknowledgments
CH
2
), 2.40–1.38 (19H, several m, 3· CH and 8· CH
2
),
1
3
0
2
1
3 3
.90 (3H, s, 18-CH ). RMN- C (50 MHz, CDCl
): d
13.9 (C-17), 171.8 (COOCH ), 155.0 (C-3), 137.4 (C-5),
32.7 (C-10), 126.1 (C-1), 116,5 (C-4), 114,0 (C-2), 96.2
The authors wish to thank the Fonds de Recherche sur
la Nature et les Technologies du Qu e´ bec (FQRNT), the
Natural Sciences and Engineering Research Council of
Canada (NSERC) and the Canadian Institutes for
Health Research (CIHR) for useful financial support.
3
(CH for THP), 71.9, 70.1 and 67.8 (4· OCH
represents 2C), 61.8 (CH
2
, 70.1
O for THP), 58.2 (COOCH ),
2
3
5
2
2.6, 49.4, 45.8, 44.0, 37.8, 34.7, 32.1, 31.0, 30.4, 29.5, 26.5,
5.7, 25.2, 18.8, 14.2 (C-18), 3.1 (CH I). MS (m/e),
2
+
Å
+Å
1
C
31
H
43
I
Calcd for C H I O = 654.2053; found = 654.2042.
1
O
7
: 654 (M ), 570 (MꢀC
5 8
H O ) . Exact mass:
3
1
43 1
7
References and notes
Spectral data for 16b-hydroxymethyl-16a-[8-iodo-3,6-
dioxaoctyl]-1,3,5(10)-estratrien-3,17b-diol (12b): IR
(NaCl, mmax, cm ): 3369 (O–H), 1616, and 1506 (C@C
ꢀ
1
1
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aromatic). H NMR (200 MHz, acetone-d ): d 7.92 (1H, s,
6
2
phenol-OH), 7.09 (1H, d, J = 8.6 Hz, 1-CH), 6.59 (1H, dd,
J = 8.6 Hz and 2.5 Hz, 2-CH), 6.52 (1H, d, J = 2.3 Hz, 4-
2
05, 698.
3
4
5
. Wong, E.; Giandomenico, C. M. Chem. Rev. 1999, 99, 2451.
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CH), 4.20 (1H, d, J = 4.3 Hz, CH
m, CHOH, CH
OH and 4· OCH
J = 6.4 Hz, CH I), 2.75 (2H, m, 6-CH ), 2.31–1.11 (15H,
several m, 2· OH, 3· CH and 5· CH ), 0.88 (3H, s, 18-
): d 155.9 (C-3),
138.4 (C-5), 132.1 (C-10), 127.0 (C-1), 115.9 (C-4), 113.6
(C-2), 90.2 (C-17), 72.5, 70.9, 70.6, 69.1 and 67.4 (CH OH
and 4· OCH on PEG chain), 48.2, 46.9, 45.7, 44.8, 40.0,
39.1, 38.9, 35.8, 30.2, 28.3, 27.2, 12.5 (C-18), 4.1(CH I).
O) . Exact
= 544.1686; found =
a
OH), 3.78–3.39 (10H,
0
), 3.34 (2H, t,
2
a
2
2
2
1
3
6
. (a) Reedijk, J. Inorg. Chim. Acta 1992, 198, 873; (b)
Lemaire, D.; Fouchet, M.-H.; Kozelka, J. J. Inorg.
Biochem. 1994, 53, 261; (c) Hydes, P. C.; Russell, M. J.
H. Cancer Metastasis Rev. 1988, 7, 67.
CH ). C NMR (50 MHz, acetone-d
3 6
2
2
7
. Cepeda, V.; Fuertes, M. A.; Castilla, J.; Alonso, C.;
Quevedo, C.; P e´ rez, J. M. Anticancer Agents Med. Chem.
2
+
Å
+Å
MS (m/e), C25
H
37
I
1
O
5
: 544 (M ), 526 (MꢀH
2
2
007, 7, 3.
mass: Calcd for
25 37 1 5
C H I O
8
9
. Kostova, I. Recent Patents Anticancer Drug Disc. 2006, 1, 1.
. Gust, R.; Ott, I. Anticancer Agents Med. Chem. 2007, 7, 95.
544.1675. Spectral data for 16b-hydroxymethyl-16a-[8-
(2-pyridine-2-yl-ethylamino)-3,6-dioxaoctyl]-1,3, 5(10)-
estratrien-3,17b-diol dichloroplatinum(II) (1b, n = 2): IR
1
1
0. von Angerer, E. In Metal Complexes in Cancer Chemo-
therapy; Keppler, B. K., Ed.; VCH: Weinheim, 1993; pp
ꢀ1
(KBr, mmax, cm ): 3430–3170 (O–H and N–H), 1611 and
1
7
5–83.
1502 (C@C aromatic). H NMR (200 MHz, acetone-d ): d
6
1. Kounelis, S.; Kapranos, N.; Kouri, E.; Coppola, D.;
Papadaki, H.; Jones, M. W. Mod. Pathol. 2000, 13, 379.
2. Rao, B. R.; Slotman, B. J. Endocr. Rev. 1991, 12, 14.
3. Canadian Cancer Society, Statistics for 2006 at http://
www.cancer.ca.
9.12 (1H, d, J = 5.9 Hz, a-CH), 8.04 (1H, t, J = 7.6 Hz, c-
CH), 7.96 (1H, s, phenol-OH), 7.55 (1H, d, J = 7.8 Hz, d-
CH), 7.42 (1H, t, J = 6.6 Hz, b-CH), 7.08 (1H, d,
J = 8.6 Hz, 1-CH), 6.60 (1H, dd, J = 8.4 Hz and 2.5 Hz,
2-CH), 6.53 (1H, d, J = 2.7 Hz, 4-CH), 6.12 (1H, s, NH),
1
1
1
1
1
4. Desc oˆ teaux, C.; Provencher-Mandeville, J.; Mathieu, I.;
4.24 (1H, m, CH
a
OH), 3.10–2.81 (16H, several m, CHOH,
on PEG chain and OCH CH
-pyridine), 2.75 (2H, m, 6-CH ), 2.57–1.21
(15H, several m, 2· OH, 3· CH and 5· CH ), 0.89 (3H, s,
): d 159.9 (C-e),
´
Perron, V.; Mandal, S. K.; Asselin, E.; B e´ rub e´ , G. Bioorg.
Med. Chem. Lett. 2003, 13, 3927.
0
CH
a
OH, 4· OCH
CH
2
2
2
NHCH
2
2
2
`
5. Gagnon, V.; St-Germain, M.-E.; Desc oˆ teaux, C.; Proven-
2
1
3
´
cher-Mandeville, J.; Parent, S.; Mandal, S. K.; Asselin, E.;
B e´ rub e´ , G. Bioorg. Med. Chem. Lett. 2004, 14, 5919.
18-CH
3
). C NMR (50 MHz, acetone-d
6
155.3 (C-3), 153.7 (C-a), 139.4 (C-c), 137.8 (C-5), 131.5 (C-
10), 126.4 (C-1), 124.8 (C-d), 123.8 (C-b), 115.3 (C-4),
´
6. Perron, V.; Rabouin, D.; Asselin, E.; Parent, S.; Gau-
dreault, R. C.; B e´ rub e´ , G. Bioorg. Chem. 2005, 33, 1.
7. B e´ rub e´ , G. US Patent 7,153,844, 2006.
8. Carmichael, J.; DeGrapp, W. G.; Gazdar, A. F.; Minna, J.
D.; Mitchell, J. B. Cancer Res. 1987, 47, 936.
9. Ford, C. H. J.; Richardson, V. J.; Tsaltas, G. Cancer
Chemother. Pharmacol. 1989, 24, 295.
0. Zhao, Y.; Jona, J.; Chow, D. T.; Rong, H.; Semin, D.;
Xia, X.; Zanon, R.; Spancake, C.; Maliski, E. Rapid
Commun. Mass Spectrom. 2002, 16, 1548.
113.0 (C-2), 89.6 (C-17), 70.0, 68.8, 68.7 and 66.7 (CH
and 4· OCH on PEG chain, 70.0 represents 2C), 55.7,
47.6, 46.6, 46.4, 45.1, 44.2, 39.7, 39.4, 38.5, 38.4, 35.6, 29.6,
27.7, 26.6, 12.1 (C-18). MS (m/e), C32 Pt: 804.2
Pt = 804.
25043 (M+H) ; found = 804.25045 and calcd for C32
2
OH
1
1
2
H
H
46Cl
46Cl
N O
2 2 5
N O
2 2 5
+
1
2
(M+H) . Exact mass: Calcd for C32
+
H
46
+
Cl N O Pt = 826.23237 (M+Na) ; found = 826.23244.
2 2 5
1
8
OH
1
2
11
9
1
7
OH
1
3
1
4
H
2 N
Pt
Cl
2
2
2
1. Greene, T. W.; Wuts, P. G. M. In Protective Groups in Organic
Synthesis, 3rd ed.; John Wiley & Sons: New York, 1999.
2. Ruest, L.; Blouin, G.; Deslongchamps, P. Synth. Commun.
1
0
16
O
2
14
1
5
8
e
Cl
d
7
3
5
HO
6
N
a
1
976, 6, 169.
3. Tremblay, R.; Auger, S.; Poirier, D. Synth. Commun.
995, 25, 2483.
c
b
1
1
26. Otto, A. M.; Faded, M.; Schonenberger, H. Cancer Res.
b
2
2
4. Dionne, P.; Ngatcha, B. T.; Poirier, D. Steroid 1997, 62, 674.
5. Spectral data for 16a-[8-iodo-3,6-dioxaoctyl]-16b-(meth-
oxycarbonyl)-3-(tetrahydropyran-2-yloxy)-1,3,5(10)-estra-
1991, 51, 3217.
27. Karl, J.; Gust, R.; Spruss, T.; Schneider, M. R.; Schonen-
berger, H.; Engel, J.; Wrobel, K. H.; Lux, F.; Haeberlin, S.
T. J. Med. Chem. 1988, 31, 72.
ꢀ
1
trien-17-one (11b): IR (NaCl, mmax, cm ): 1752 (C@O,
ester), 1721 (C@O, ketone), 1609, and 1496 (C@C
1
aromatic). H NMR (200 MHz, CDCl
TM
3
): d 7.12 (1H, d,
J = 8.6 Hz, 1-CH), 6.75 (2H, m, 2-CH and 4-CH), 5.3 (1H,
28. The HitHunter EFC Estrogen Fluorescence assay kit
was obtained from Discoverx, Fremont, CA (http://
www.discoverx.com).
m, CH), 3.86 (1H, m, CH H O (on THP)), 3.67 (3H, s,
a
b
COOCH
OCH ), 3.19 (2H, t, J = 6.8 Hz, CH
3
), 3.52 (9H, m, CH
b
H
a
O (on THP) and 4·
I), 2.83 (2H, m, 6-
29. CACheWorkSystem Pro, version 6.1.12, Fujitsu, USA, 2006.
30. Available from: http://www.rcsb.org/pdb/.
2
2