Inhibition of 17β-HSD1: SAR of bicyclic substituted hydroxyphenylmethanones and discovery of new potent inhibitors with thioether linker

Article abstract of DOI:10.1016/j.ejmech.2014.05.074

Estradiol is the most potent estrogen in humans. It is known to be involved in the development and proliferation of estrogen dependent diseases such as breast cancer and endometriosis. The last step of its biosynthesis is catalyzed by 17β-hydroxysteroid d

Full text of DOI:10.1016/j.ejmech.2014.05.074

European Journal of Medicinal Chemistry 82 (2014) 394e406
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Inhibition of 17
b-HSD1: SAR of bicyclic substituted
hydroxyphenylmethanones and discovery of new potent inhibitors
with thioether linker
Ahmed S. Abdelsamie a, Emmanuel Bey b, Nina Hanke b, Martin Empting c,
,
, *
Rolf W. Hartmann a c, Martin Frotscher a
a Pharmaceutical and Medicinal Chemistry, Saarland University, Campus C23, D-66123 Saarbrücken, Germany
b ElexoPharm GmbH, Campus C11, D-66123 Saarbrücken, Germany
c Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Campus C23, D-66123 Saarbrücken, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Estradiol is the most potent estrogen in humans. It is known to be involved in the development and
proliferation of estrogen dependent diseases such as breast cancer and endometriosis. The last step of
Received 26 September 2013
Received in revised form
27 May 2014
Accepted 31 May 2014
Available online 3 June 2014
its biosynthesis is catalyzed by 17
quently is a promising target for the treatment of these diseases. Recently, we reported on bicyclic
substituted hydroxyphenylmethanones as potent inhibitors of 17 -HSD1. The present study focuses on
b-hydroxysteroid dehydrogenase type 1 (17b- HSD1) which conse-
b
rational structural modifications in this compound class with the aim of gaining more insight into its
structureeactivity relationship (SAR). (4-Hydroxyphenyl)-(5-(3-hydroxyphenylsulfanyl)-thiophen-2-
Keywords:
yl)methanone (25) was discovered as a member of a novel potent class of human 17
hibitors. Computational methods were used to elucidate its interactions with the target protein. The
compound showed activity also towards the murine 17 -HSD1 enzyme and thus is a starting point for
the design of compounds suitable for evaluation in an animal disease model.
© 2014 Elsevier Masson SAS. All rights reserved.
b-HSD1 in-
Human 17
type 1 (h17
m17 -HSD1
b
-Hydroxysteroid dehydrogenase
b
-HSD1) inhibitors
b
b
Bicyclic substituted
hydroxyphenylmethanones (BSHs)
Estrogen mimetics
Non-steroidal inhibitors
Estrogen-dependent diseases
1. Introduction
the majority of breast cancers, and uterine leiomyoma [4e7]. Besides
surgery, chemo- and immunotherapy, the inhibition of estrogen
biosynthesis and the blockade of estrogen action, respectively, are
today standard therapies for these diseases. These treatments (with
aromatase inhibitors, GnRH-analogs, antiestrogens, selective estro-
gen receptor modulators (SERMs)), however, have a systemic mode
of action, i.e. they reduce estrogen effects not only in the diseased
tissue. As a result, they may lead to considerable side effects. A novel
approach mainly aiming at lowering intracellular estrogen produc-
tion in the diseased tissue could be a significant improvement for
EDD therapy. Such an intracrine approach is presently being pursued
using steroid sulfatase inhibitors in the treatment of hormone-
dependent cancers [8], and is already successfully applied in the
The important roles of estrogens and androgens in female and
male development and reproduction are well known [1]. They exert
theireffects by transactivation of the respective nuclear receptors[2],
although also non-genomic effects are discussed [3]. However, these
steroidal sex hormones are also involved in the genesis and the
progression of diseases. Estrogens are known to stimulate the pro-
gression of estrogen-dependent diseases (EDD) like endometriosis,
Abbreviations: 17
b
-HSD1, 17
b
-hydroxysteroid dehydrogenase type 1; 17
b-HSD2,
17
b-hydroxysteroid dehydrogenase type 2; E1, estrone; E2, 17b
-estradiol; ER, es-
trogen receptor; SERM, selective estrogen receptor modulator; GnRH, gonado-
tropin-releasing hormone; NADP(H), nicotinamide adenine dinucleotide
phosphate; NAD(H), nicotinamide adenine dinucleotide; RBA, relative binding af-
finity; DAST, diethylaminosulfur trifluoride; HPLC, high performance liquid chro-
matography; CC, column chromatography; TLC, thin layer chromatography; DCM,
dichloromethane.
* Corresponding author.
E-mail addresses: m.frotscher@mx.uni-saarland.de, m.frotscher@arcor.de
(M. Frotscher).
treatment of androgen dependent diseases (ADD) by using 5
a-
reductase inhibitors [9].
More recently, 17b-hydroxysteroid dehydrogenase type 1 (17
b
-
HSD1, SDR28C1) has attracted attention as a potential target for the
treatment of EDD. The enzyme catalyses the final step of estradiol
(E2) biosynthesis which is the most potent estrogen in humans
(Fig. 1).
http://dx.doi.org/10.1016/j.ejmech.2014.05.074
0223-5234/© 2014 Elsevier Masson SAS. All rights reserved.

A.S. Abdelsamie et al. / European Journal of Medicinal Chemistry 82 (2014) 394e406
395
O
OH
d) The close proximity of the side chains of Tyr218 and Ser222
to the inhibitor
17β-HSD1, NAD(P)H
17β-HSD2, NAD+
In order to evaluate the structure activity relationships, and also
to validate the docking results in this compound class, the different
structural features mentioned above (a-c) were replaced by
possible bioisosteres or other functional groups, see Fig. 4 (modi-
fications a-c). Endeavors to replace the hydroxyl group of the
benzoylic part (modification a) were essentially focussed on small,
planar substituents which were the basis for subsequent enlarge-
ments. This approach reflects previous results which indicate that
the introduction of substituents larger than fluorine to the
HO
HO
E1
Fig. 1. Interconversion of estrone (E1) and estradiol (E2).
E2
17b-HSD1 is described to be overexpressed at mRNA level in
breast cancer tissue [10e12] and endometriotic lesions [13]. Since a
more local mode of action can be anticipated compared to existing
medical treatments, its selective inhibition is regarded as a prom-
ising strategy for the treatment of EDD, with the prospect of less
hydroxybenzoyl moiety is detrimental for 17b-HSD1 inhibition
[32]. Furthermore, attempts were made to establish additional
hydrogen bonding interactions to Tyr218 and Ser222 by intro-
ducing an appropriate second linker function between the het-
erocycle and the hydroxyphenyl moiety (modification d). Due to its
ability to act as a hydrogen bond acceptor, the sulfone group was
chosen as linker function. The precursors in the syntheses of the
prepared sulfones, the corresponding thioethers, have also been
tested for activity.
side effects. No 17b-HSD1 inhibitor has entered clinical trials until
now, but there is experimental evidence that inhibition of the
enzyme is effective against estrone (E1) induced growth of human
tumor cells in vitro and in vivo [14e17]. The availability of com-
pounds not only inhibiting the human enzyme but also 17
of another species would be a prerequisite for a proof of principle
b-HSD1
study concerning the applicability of 17
b-HSD1 inhibitors in the
treatment of endometriosis.
3. Chemistry
17b-HSD2 can be considered as a functional counterpart of the
type 1 enzyme as it de-activates E2 by transforming it to E1. Thus, it
plays a protective role against too high E2 concentrations and
The synthesis of compounds 1e16 (Scheme 1) started from 2-
bromothiophene which e for the preparation of 1e5 e was
coupled with phenylboronic acid in a Suzuki-reaction [33]. Frie-
deleCrafts acylation of the resulting intermediate 1a [34] with the
appropriate benzoic acid chloride gave access to compounds 1e4
[35]. The intermediate 17c, which was the starting material for the
syntheses according to Scheme 2, was prepared in the same way.
Saponification of the ester 4 led to the carbonic acid 5.
should therefore not be inhibited by 17
b-HSD1 inhibitors.
Both steroidal [18,19] and non-steroidal [20e31] 17
b
-HSD1 in-
hibitors have been described in the past. Recently we reported on
bicyclic substituted hydroxyphenylmethanones [32] (general
structure, Fig. 2) which combine low molecular weight with high
inhibitory potency (high ligand efficiency) and show strong intra-
cellular activity. The aim of the present study is to obtain more
insight in the structure activity relationships (SARs) of this com-
pound class by rational structural modifications. Moreover, the
inhibitory activities of the synthesized compounds are used to
verify previous docking results [32] using a broader base of bio-
logical data.
For the synthesis of compounds 6e16, 2-bromothiophene was
converted into the ketone 6b [36] via FriedeleCrafts acylation with
3-nitrobenzoyl chloride. Reduction of the nitro-group with stan-
nous chloride dihydrate yielded amine 6a which was submitted to a
Suzuki reaction with 3-ethoxyphenylboronic acid. The resulting
compound 6 was reacted with 2-bromopropane and benzyl bro-
mide to afford the secondary amines 8 and 10, respectively. In the
synthesis of the former, copper(II)-oxide had to be added as a
catalyst. The thiourea 9 was obtained by reaction of 6 with meth-
ylisothiocyanate. The reaction of 6 with sulfonic acid chlorides at
room temperature yielded the corresponding sulfonic acid amides
7 and 11e13. For the analogous preparation of the carbonic acid
amides 14 and 15, higher reaction temperatures had to be applied
(pyridine, reflux, overnight). Hydrolysis of the ester 15 under basic
conditions resulted in the formation of the carbonic acid 16.
Starting point for the modifications of the carbonyl group be-
tween the aromatic moieties was compound 17c (Scheme 2). The
conversion to the CF2-group (compound 17a) with DASTcould not be
achieved directly but after formation of the thioketone 17b using
Lawesson's reagent [37]. From 17a and 17b, the corresponding phe-
nols 17 and 18 could be obtained by ether cleavage (BBr3, method D)
[38]. Reduction of the keto function of compound 17c with stannous
chloride dihydrate yielded the methylene intermediate 19a, whereas
Wittig reaction with methyltriphenylphosphonium bromide affor-
ded the olefin 20a. Upon treatment with BBr3 in anhydrous CH2Cl2
(method D) both 19a and 20a underwent demethylation, resulting in
the final compounds 19 and 20, respectively.
2. Design
Starting point for the design of compounds 1e28 (Chart 1) were
our conceptions concerning the binding mode of bicyclic
substituted hydroxyphenylmethanones (Fig. 3) [32]: Previous mo-
lecular docking results suggest
a) A hydrogen bond interaction of the hydroxy group of the
benzoyl moiety with Asn152
b) A bifurcated H-bond between the carbonyl group and the
hydroxyl groups of Ser142 and Tyr155
c) Another bifurcated H-bond between the OH-group of the
hydroxyphenyl moiety and the side chains of His221 and
Glu282
R2
O
R1
S
The first step in the synthesis of compounds 21e24 was a Frie-
deleCrafts acylation (method A) of 2-bromothiophene with 3-
methoxybenzoylchloride, leading to the benzoylated key intermedi-
ate 21b [32]. The corresponding 4-methoxy isomer 27b, which was
the starting material for one of the syntheses depicted in Scheme 4,
was synthesized accordingly. Compounds 21 and 22 were prepared
HO
Fig. 2. Bicyclic substituted hydroxyphenylmethanones: General structure.

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A.S. Abdelsamie et al. / European Journal of Medicinal Chemistry 82 (2014) 394e406
Cpd R1
R2
X
-
Y
-
Cpd R1
3-OH
R2
W
Z
H
H
H
CF2
-
1
17
18
19
20
21
22
23
24
25
26
27
28
CH3
H
-
-
3-OH
3-OH
3-OH
3-OH
3-OH
3-OH
3-OH
3-OH
3-OH
4-OH
4-OH
H
C=S
CH2
C=CH2
C=O
C=O
C=O
-
2
Cl
H
-
-
H
-
3
COOCH3
COOH
NH2
H
-
-
H
-
4
H
-
-
3-CH2OH
4-CH2OH
3-OCH(CH3)2
-
5
OC2H5
OC2H5
OC2H5
-
-
-
6
NHSO2CF3
NHCH(CH3)2
-
-
-
7
-
-
3-OCH2CH(CH3)2 C=O
-
8
NHC(S)NHCH3 OC2H5
-
-
3-OH
3-OH
3-OH
3-OH
C=O
C=O
C=O
C=O
S
9
-
-
-
-
-
-
-
OC2H5 CH2
OC2H5 SO2
H
H
SO2
S
10
11
12
13
14
15
16
OC2H5 SO2 3-CN
SO2
OC2H5 SO2 4-OCH3
OC2H5 CO
H
OC2H5 CO CO2CH3
OC2H5 CO CO2H
Chart 1. Synthesized compounds.
from 21b by Suzuki cross coupling reactions with the appropriate
commerciallyavailable boronicacids, resulting in compounds 21a and
22a, and subsequent demethylation. The synthetic pathway leading
from 21b to the final compounds 23 and 24 required the replacement
of the methoxy- by a benzyloxy-group (compound 23c) which was
accomplished via the phenolic intermediate 23d [32]. A subsequent
Suzuki cross coupling reaction with 3-hydroxyphenylboronic acid led
to compound 23b which was alkylated using isopropyl- and isobutyl
iodide to afford the ethers 23a and 24a, respectively. Selective
debenzylation using BCl3 instead of BBr3 (method D) yielded the final
compounds 23 and 24 (Scheme 3).
presence of potassium hydroxide and copper(I)-oxide as catalyst.
The methoxy functions were cleaved with BBr3 according to method
D to yield the hydroxylated compounds 25 and 27. The sulfones 26
and 28 were obtained from 25 and 27, respectively, by oxidation
with hydrogen peroxide in acetic acid at room temperature.
4. Biological results
4.1. Inhibition of human 17
17 -HSD2
b-HSD1 and selectivity towards human
b
The synthesis of sulfides (25 and 27) and sulfones (26 and 28) is
depicted in Scheme 4. The intermediates 21b and 27b were trans-
formed into the sulfides 25a and 27a, respectively, using 3-
methoxybenzenethiol in aqueous dimethylformamide in the
Human placental enzymes were used for both assays and were
obtained according to the methods described [39e41]. In the h17
HSD1 assay, incubations were carried out with cytosolic fractions,
tritiated E1, cofactor and inhibitor. The separation of substrate and
b-

A.S. Abdelsamie et al. / European Journal of Medicinal Chemistry 82 (2014) 394e406
397
[30]. Simple omission of the OH-group (modification a; Fig. 4), i.e.
replacement with H, led to the inactive compound 1 (Table 1).
Furthermore, several small and essentially planar functionalities
such as Me, Cl, CO2H, CO2CH3, and NH2 (compounds 2e6, respec-
tively) were introduced. The substituents were chosen considering
the Craig plot (variation of the size, lipophilicity, and electronic
properties) [42] as well as their different abilities to form hydrogen
bond interactions with the target. Compounds 1e5 were inactive or
Tyr218
Ser142
OH
HO
OH
O
O
O
OH
Glu282
S
Tyr155
showed only marginal inhibition of 17
an amino group led to the conservation of a residual activity
(compound 6, 24% inhibition at 1 M).
b-HSD1. The introduction of
HN
OH
Ser222
N
HO
m
Attempts were made to enhance the inhibitory activity of
compound 6 by modulating the hydrogen bonding properties of the
NH2-group. For this purpose, several electron-withdrawing or
edonating substituents were introduced. These modifications,
however, led to a complete loss of activity (compounds 7e16, Chart
1), probably due to the bulkiness of the introduced groups.
His221
O
H2N
Asn152
Fig. 3. Schematic H-bond interactions of bicyclic substituted hydrox-
yphenylmethanones with 17 -HSD1 [32].
b
4.1.2. Modification b
Modifications of the keto-linker function (modification b; Fig. 4)
had a strong impact on biological activity, depending on the nature of
the linker group: The thioketo-analog 18 of the reference compound
A only showed a slightly reduced inhibitory potency (75% vs. 80%
inhibn. at 1 mM, Table 2). In contrast, replacement of the keto-group
with an olefinic moiety (compound 20) or saturated groups (com-
pounds 17 and 19) led to a strong decrease of inhibitoryactivity. None
product was accomplished by HPLC. The h17
formed similarly using tritiated E2 as substrate and a microsomal
fraction. Activities are given as percent inhibition at
(Tables 1e3). For the most active compounds IC50 values are reported
(Table 3). Compounds AeC identified in our previous work were used
as reference compounds [32]. All methylated intermediates showed
b-HSD2 assay was per-
1
mM
of the four compounds 17e20 showed selectivity over 17
b-HSD2.
no activity towards both h17b-HSD1 and 2 (data not shown).
4.1.3. Modification c
4.1.1. Modification a
Another structural element under investigation in this study
was the phenolic OH-group in ring C which was replaced by a
hydroxymethyl-group and different ether functions (modification
c; Fig. 4). These structural variations led to highly active
In the search for an appropriate replacement of the hydroxy-
group at the benzoyl moiety, several structural modifications
starting from the reference compounds A and B were investigated
Fig. 4. Design of potential inhibitors 1e28.

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A.S. Abdelsamie et al. / European Journal of Medicinal Chemistry 82 (2014) 394e406
Cl
O
HO
OH
B
R
O
Br
S
S
a
b
S
1a
Cl
O
R
1, R = H; 2, R = CH3; 3, R = Cl;
4, R = COOCH3;
b
c
NO2
5, R = COOH:
17c, R = OCH3.
Br
d
a
O
O
S
S
Br
O
S
O
H2N
H2N
O2N
6a
6
6b
e
e
f
O
S
O
S
O
S
R
O
O
O
HN
HN
R
HN
X
O
COOH
10-15
7-9
16
cpd
7
R
cmpd
10
X
R
H
H
cpd
13
X
R
SO2CF3
CH(CH3)2
C(S)NHCH3
CH2
SO2
SO2
SO2
CO
CO
4-OMe
H
8
11
14
3-CN
COOMe
9
12
15
Scheme 1. a) method B, Cs2CO3, Pd(PPh3)4, DME/water (1:1), reflux, 18 h. b) method A, AlCl3, anhydrous CH2Cl2, 0 ꢀC, 0.5 h to rt, overnight. c) LiOH, MeOH/H2O (7:3). d) SnCl2$2H2O,
CH3OH, reflux, 2 h. e) method C, RSO2Cl or RCOCl, Pyridine, rt or reflux, overnight (compounds 7, 11e15); 2-bromopropane, CuO, KOH, DMF, reflux, 4 days (compound 8); CH3NCS,
THF, Et3N, reflux, overnight (compound 9); (bromomethyl)benzene, K2CO3, acetone, rt, 10 h (compound 10). f) 10% NaOH, ethanol, reflux, 2 h.
compounds: The formal insertion of CH2 between the aromatic ring
(3- or 4-position) and the OH-group afforded the benzylic alcohols
hydroxybenzoyl moiety, the SAR of these novel compounds with
two linker functions appears to be similar to that discovered pre-
viously for compounds bearing the keto-linker group only [32]. The
compounds 25e28 showed comparable IC50-values for the inhibi-
21 and 22, showing complete inhibition of h17b-HSD1 at a con-
centration of 1 M (Table 2). Also the bulky ether derivatives 23 and
m
24 strongly inhibited the target enzyme. All four compounds dis-
played similarly low IC50-values in the range of 90 nMe157 nM
(Table 3), but no selectivity over the type 2 enzyme with the
exception of compound 24 (SF ¼ 5.5).
tion of h17
4.2. Inhibition of murine 17
The murine 17 -HSD1 enzyme was expressed in HEK293 cells.
b
-HSD1 and 2 (Table 3).
b-HSD1
b
4.1.4. Modification d
The inhibitory potencies of compound 25 and the reference com-
pound C were evaluated in an assay similar to that of the human
enzyme.
Compounds bearing an additional linker group, namely be-
tween the thiophene ring and the hydroxyphenyl ring C (modifi-
cation d; Fig. 4), showed slightly reduced activity towards the target
enzyme, compared to the reference C (IC50 ¼ 22 nM) when the OH-
group on the benzoyl moiety was in the 4-position (compounds 27
and 28, Tables 2 and 3). Moving the OH-group to the 3-position,
however, resulted in compounds 25 and 26 with higher activities
(IC50 ¼ 104 nM and 275 nM, respectively). Thus, regarding the
Compound 25 turned out to be an inhibitor of murine 17
b-HSD1
(20% inhibn. at 1 M; C: 10%). This is remarkable since the human
m
and the murine enzymes differ considerably in their primary
structure [43] and most of the compound classes described by us to
show strong inhibition of human 17
b-HSD1 are inactive towards the
murine enzyme (unpublished results). Thus, compound 25 is a

A.S. Abdelsamie et al. / European Journal of Medicinal Chemistry 82 (2014) 394e406
399
F
c
F
F
S
S
S
F
S
17a
17
HO
HO
HO
O
b
b
O
S
S
S
S
a
c
17c
17b
18
O
O
d
e
S
S
c
20a
19a
19
O
O
c
S
HO
20
Scheme 2. a) Lawesson's reagent, toluene, reflux, 2 h. b) DAST, abs. CH2Cl2, rt, 3 h. c) method D, BBr3, CH2Cl2, ꢁ78 ꢀC to rt, overnight. d) SnCl2$2H2O, acetic acid, HCl, reflux,
overnight. e) methyltriphenylphosphonium bromide, n-BuLi, abs. THF, rt for 2.5 h then 65 ꢀC overnight.
valuable starting point for the design of more potent and selective
inhibitors of the murine enzymes that allow for in vivo evaluation
(proof of principle).
with the higher inhibitory potency of 25 (IC50 ¼ 104 nM; Table 3)
compared to 26 (IC50 ¼ 275 nM).
6. Discussion and conclusions
5. Molecular modeling
The aim of our study was the elucidation of structure activity
relationships in the class of bicyclic substituted methanones which
have previously been identified as highly active inhibitors of the
Computational methods were used in order to elucidate the
binding modes of the novel inhibitors with two linker functions.
Molecular docking results indicate that both thioether 25 and sul-
h17b-HSD1 enzyme [30,32]. One of the structural features under
fone 26 fit well into the steroid binding pocket of h17
b
-HSD1
investigation was the phenolic OH-group at the benzoyl moiety
(ring A) of inhibitors A and B It was replaced with substituents
which covered a broad spectrum of lipophilic and electronic
properties and differed in their abilities to form hydrogen bond
interactions with the target. The introduction of chlorine appeared
(Fig. 5). Interestingly, they dock inversely: The sulfone moiety of
compound 26 and the keto-group of 25 are located in the same
region of the binding pocket which is distant from Tyr218 and
Ser222. An interaction of the sulfone group with these amino acids,
which was aimed at, would thus be unlikely.
interesting to us as it is known that this substituent, due to its s-
Ligand-protein interactions can be seen in more detail in Fig. 6:
Both compounds form a hydrogen bond with the key amino acid
residue, Ser142. Considering compound 25, this bond is formed via
the keto-group of the inhibitor, whereas in case of compound 26
the sulfone moiety is the interaction partner for Ser142 while the
keto-group does not appear to play a role in protein binding.
The reversed docking poses of 25 and 26 seem to have an
additional effect on ligandeprotein interaction: Whereas both
phenolic OH-groups of compound 25 are suggested to be involved
in hydrogen bonding (with Tyr155 and His221), only one such
interaction (with Glu282) can be found for 26. This is in agreement
hole property, is able to replace classical donors like OH in H-
bonding interactions [44]. On the other hand, also hydrogen bond
acceptors (such as an ester or a carboxylate function) seemed
promising, as it was hypothesized earlier that the OH-group of the
inhibitor e as a donor e forms a hydrogen bond with the carbonyl
function of the Asn152 side chain [32]. This amino acid residue,
however, is in principle also able to act as an H-bond donor via its
NH2-group, allowing for an interaction with an appropriate
acceptor function of the inhibitor. Regardless of the properties of
the chosen residue, however, a complete loss or a strong reduction
of inhibitory activity was observed (compounds 2e5). Similarly

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A.S. Abdelsamie et al. / European Journal of Medicinal Chemistry 82 (2014) 394e406
Cl
O
HO
OH
B
Br
O
S
O
OH
S
O
O
S
OH
OH
Br
c
b
S
a
O
HO
O
21b, 3-OCH3
27b, 4-OCH3
21a, 3-CH2OH
22a, 4-CH2OH
21, 3-CH2OH
22, 4-CH2OH
HO
OH
B
c
Br
Br
OH
O
O
O
S
S
S
OH
d
b
HO
BnO
BnO
23d
23c
23b
d
O
O
S
S
R
R
e
HO
BnO
23, R = OCH(CH3)2
24, R = OCH2CH(CH3)2
23a, R = OCH(CH3)2
24a, R = OCH2CH(CH3)2
Scheme 3. a) method A, AlCl3, anhydrous CH2Cl2, 0 ꢀC, 0.5 h to rt, overnight. b) method B, Cs2CO3, Pd(PPh3)4, DME/water (1:1), reflux, 18 h. c) method D, BBr3, CH2Cl2, ꢁ78 ꢀC to rt,
overnight. d) ReI, Cs2CO3, acetone, reflux, overnight. e) method D, BCl3, CH2Cl2, ꢁ78 ꢀC to rt, overnight.
sharp structure activity relationships have also been reported for
other classes of 17b-HSD1 inhibitors [28,45]. At physiological pH,
the NH2-group is the only classical hydrogen bond donor of the
substituent selection. Because of its low basicity (pKA z 3.1,
Table 1
Inhibition of human 17b-HSD1 and 17b-HSD2 by compounds A, B and 1e6.
O
O
S
S
O
R
R
A, 1-5
B, 6
Cpd
R
% Inhibition @ 1 m
Ma
h17
b
-HSD1b
h17
b
-HSD2c
A
1
2
3
4
5
OH
H
CH3
Cl
COOCH3
COOH
80
n.i.
14
n.i.
14
18
94
n.i.
n.i.
n.i.
11
n.i.
B
6
OH
NH2
88
24
69
n.i.
a
Mean value of three determinations, standard deviation less than 15%.
b
Human placenta, cytosolic fraction, substrate [3H]-E1, 500 nM, cofactor NADH,
500
m
M.
c
Scheme 4. a) Cu2O, KOH, DMF, 135 ꢀC, 2 h. b) method D, BBr3, CH2Cl2, ꢁ78 ꢀC to rt,
Human placenta, microsomal fraction, substrate [3H]-E2, 500 nM, cofactor
overnight. c) H2O2 (30%), acetic acid, rt, 4 days.
NADþ, 1500
m
M. n.i. ¼ no inhibition (inhibition < 10%).

A.S. Abdelsamie et al. / European Journal of Medicinal Chemistry 82 (2014) 394e406
401
Table 2
Inhibition of human 17
b
-HSD1 and 17
b
-HSD2 by compounds A, C and 17e28.
HO
4
R
B
S
C
C
X
3
Y
B
S
O
3
A
HO
A
R
4
A, C, 17-24
25-28
Cpd
X
R
Y
% Inhibition @ 1 m
Ma
h17
b
-HSD1b
h17b
-HSD2c
Fig. 5. Compounds 25 and 26, docked into human 17
b-HSD1 (PDB: 1FDT). Upper left:
A
C]O
CF2
C]S
CH2
H
H
H
H
H
e
e
e
e
e
80
35
75
16
33
94
36
85
29
49
Cofactor NADPH.
17
18
19
20
bond interaction, in which the hydroxyl group at the benzoylic
moiety acts as a donor.
C]CH2
C
C]O
C]O
C]O
C]O
C]O
e
3-OH
3-CH2OH
4-CH2OH
3-O-isopropyl
3-O-isobutyl
3-OH
3-OH
4-OH
4-OH
e
89
100
100
82
85
84
70
66
62
89
100
81
73
51
70
76
79
80
In contrast to the OH-group at the benzoyl moiety (ring A, cf.
Fig. 4) of compound C, the hydroxy-function attached to the
phenyl-group (ring C) can be replaced or structurally modified to a
considerable extent. Substantial attention was paid to the analysis
of the role of the keto-group of lead compound A. Replacement of
the keto- (compound A) by the thioketo-group led to a compound
with slightly decreased activity (compound 18, Table 2). This may
be explained by the fact that the thioketone retains the geometry of
the parent compound A, but is a poorer interaction partner for
hydrogen bonding. Olefin 20 showed a significant decrease in ac-
tivity compared to 18 (33% vs. 75% inhibn. at 1
agreement with the lacking hydrogen bonding function. Com-
pounds 17 and 19 were weak inhibitors of 17 -HSD1. Both the
difluoromethylene group (compound 17) and its methylene analog
(19) show a different geometry compared to compound A due to
their sp3-hybridized carbon atoms. The finding that the fluorinated
compound 17 is a stronger inhibitor than 19 (35% vs. 16% inhibn. at
21
22
23
24
25
26
27
28
e
e
e
e
S
SO2
S
e
e
e
SO2
a
Mean value of three determinations, standard deviation less than 15%.
b
Human placenta, cytosolic fraction, substrate [3H]-E1, 500 nM, cofactor NADH,
500
m
M.
c
Human placenta, microsomal fraction, substrate [3H]-E2, 500 nM, cofactor
mM), which is in
NADþ, 1500
m
M. n.i. ¼ no inhibition (inhibition < 10%).
b
calculated using the PERCEPTA PhysChem software (ACD/Labs,
Toronto, Canada)), it should not be protonated and can thus act as a
hydrogen bond acceptor as well. The acceptor properties, however,
can be expected to be weak, due to delocalization effects. Moreover,
also the donor properties of an amino function are generally less
pronounced compared to a phenolic OH. Thus, the fact that the
amino group (compound 6) cannot replace the OH-group of com-
pound B in a satisfactory manner may be explained by more
favorable hydrogen bonding properties of the latter. The biological
data are in agreement with docking results that suggest a hydrogen
1 mM) matches with the fact that fluorine atoms may show weak
hydrogen bond accepting capabilities [46]. Thus, the biological data
obtained for compounds 17e20 is in agreement with former mo-
lecular docking studies which suggest a bifurcated H-bond inter-
action between the carbonyl-group of the inhibitor and Tyr155 and
Ser142 [32].
The introduction of a second linker function was triggered by
the concept to establish additional hydrogen bond interactions of
the inhibitor with the OH groups of Tyr218 and Ser222 (sulfones 26
and 28). As suggested by molecular docking results of 26 (Fig. 6b),
however, they showed a different binding mode compared to the
bicyclic substituted hydroxyphenylmethanone class which pre-
cludes an establishment of these hydrogen bond interactions.
The structure of the strong inhibitor 25 may be seen as the result
of a sequential enlargement of the bis(hydroxyphenyl)thiophene
compound class (Fig. 7, D) and can be considered as a starting point
for the investigation of a novel and potent class of h17b-HSD1 in-
hibitors bearing two linker groups.
In conclusion, rational structure modifications have been carried
out in order to investigate structureeactivity relationships of
bicyclic substituted hydroxyphenylmethanones (Fig. 7, C) which
have recently been described as promising non-steroidal inhibitors
Table 3
IC50 values and selectivity factors for compounds C and 21e28.
Cpd
IC50 [nM]a
SFd
h17
b
-HSD1b
h17b
-HSD2c
C
22
90
109
51
5.0
0.6
1.3
1.9
5.5
2.4
1.0
0.3
0.6
21
22
23
24
25
26
27
28
157
120
152
104
275
752
630
202
224
836
245
283
247
389
a
Mean value of three determinations, standard deviation less than 15%.
Human placenta, cytosolic fraction, substrate [3H]-E1, 500 nM, cofactor NADH,
b
500
m
M.
c
Human placenta, microsomal fraction, substrate [3H]-E2, 500 nM, cofactor
NADþ, 1500
m
M. n.i. ¼ no inhibition (inhibition < 10%).
of h17
b-HSD1. The results revealed that inhibitory activity is highly
d
Selectivity factor: IC50(17
b-HSD2)/IC50(17 -HSD1).
b
sensitive to changes in the hydroxybenzoyl part of the compounds,

402
A.S. Abdelsamie et al. / European Journal of Medicinal Chemistry 82 (2014) 394e406
Fig. 6. Suggested binding modes showing three H-bonds to Tyr155, Ser142 and His221 for compound 25 (left) and two H-bonds to Glu282 and Ser142 for 26 (right).
Tested compounds are >95% chemical purity as measured by
HPLC. The methods for HPLC analysis and a table of data for all
HO
OH
OH
tested compounds are provided in the supporting information.
S
O
S
The following compounds were prepared according to previ-
ously described procedures: 2-phenylthiophene (1a) [34], phenyl-
(5-phenylthiophen-2-yl)methanone (1) [35], (5-bromo-thiophen-
2-yl)-(3-nitrophenyl)methanone (6b) [36], (5-bromothiophen-2-
S
O
S
OH
HO
HO
yl)(3-methoxy-phenyl)methanone
(21b)
[32]
and
(5-
D, (IC50 = 173 nM)
C, (IC50 = 22 nM)
25, (IC50 = 104 nM)
bromothiophen-2-yl)(3-hydroxyphenyl)methanone (23d) [32].
The Supplementary Data section reports the synthesis of com-
pounds 3e4, 11e15, 17c, 18e25, 21ae24a, 27a, 23b, 27b, 27 and 28.
For each general synthetic procedure, one representative example
is given below.
Fig. 7. Comparison of potent h17b-HSD1 inhibitors: representatives of bis(hydrox-
yphenyl)thiophenes [31] (D) and bicyclic substituted hydroxyphenylmethanones [32]
(C) as well as compound 25.
whereas in the phenyl moiety, major changes in nature and size of
the substituent are well tolerated. The biological data obtained
support the conception that the keto linker group is involved in
hydrogen-bonding interactions with the target. The introduction of
a second linker function led to the discovery of the potent inhibitor
(4-hydroxyphenyl)-[5-(3-hydroxyphenylsulfanyl)-thiophen-2-yl]
methanone (25) which is regarded as a member of a novel inhibitor
class and a starting point for further optimization concerning
7.2. General procedure for FriedeleCrafts acylation. Method A
(2e4, 6b, 17c, 21b, 27b)
A mixture of monosubstituted thiophene derivate (1 equiv),
arylcarbonyl chloride (0.9 equiv), and aluminum trichloride
(1 equiv) in anhydrous dichloromethane was warmed to room
temperature and stirred for 3 h. 1 M HCl was used to quench the
reaction. The aqueous layer was extracted with dichloromethane.
The combined organic layers were washed with brine, dried over
magnesium sulfate, filtered, and concentrated to dryness. The
product was purified by CC.
selectivity towards h17b-HSD2 and inhibition of m17b-HSD1.
7. Experimental section
7.3. (5-Phenylthiophen-2-yl)(m-tolyl)methanone (2)
7.1. Chemical methods
The product was purified by CC (hexane/ethyl acetate 98:2);
Chemical names follow IUPAC nomenclature. Starting materials
were purchased from Aldrich, Acros, Lancaster, Maybridge, Combi
Blocks, Merck, or Fluka and were used without purification.
Column chromatography (CC) was performed on silica gel
yield: 57% (149 mg). 1H NMR (CD3COCD3)
d
7.84e7.80 (m, 2H), 7.72
(d, J ¼ 3.8 Hz, 1H), 7.71e7.67 (m, 2H), 7.61 (d, J ¼ 3.8 Hz, 1H),
7.52e7.40 (m, 5H), 2.45 (s, 3H);13C NMR (CD3COCD3)
186.62,
d
151.84, 141.70, 137.84, 135.67, 132.62, 132.41, 128.77, 128.63, 127.91,
(70e200
mm), reaction progress was monitored by thin layer
125.64, 125.52, 124.04, 20.08; MS (ESI): 279.40 (M þ H)þ.
chromatography (TLC) on Alugram SIL G UV254 (MachereyeNagel).
1H NMR and 13C NMR spectra were measured on a Bruker
AM500 spectrometer (500 MHz) at 300 K. Chemical shifts are re-
7.4. Methyl 3-(5-phenylthiophene-2-yl-carbonyl)benzoic acid (5)
ported in
d (parts per million: ppm), by reference to the hydroge-
nated residues of deuterated solvent as internal standard (CDCl3:
Methyl 3-(5-phenylthio-phene-2-yl-carbonyl)benzoate (70 mg,
0.22 mmol, 1.00 equiv) (4) was dissolved in 5 ml methanol: water
(70:30). Lithium hydroxide (15.6 mg, 0.66 mmol, 3.00 equiv) was
added and the reaction mixture stirred at 50 ꢀC for 2 h. The mixture
was cooled to room temperature, quenched with 1 N NaOH (pH
10e12) and washed two times with ethyl acetate. The aqueous
layer was acidified with 1 N HCl to pH 1 and extracted three times
with ethyl acetate. The combined organic layers were dried over
magnesium sulfate, filtered and evaporated under reduced pres-
sure. No further purification was required; yield: 95% (65 mg; white
d
d
d
d
¼ 7.24 ppm (1H NMR) and
d
¼ 77 ppm (13C NMR), CD3OD:
¼ 3.35 ppm (1H NMR) and
¼ 2.05 ppm (1H NMR) and
¼ 2.50 ppm (1H NMR) and
d
¼ 49.3 ppm (13C NMR), CD3COCD3:
¼ 29.9 ppm (13C NMR), CD3SOCD3
¼ 39.5 ppm (13C NMR)). Signals are
d
d
described as s, d, t, dd, ddd, m, dt, q, sept for singlet, doublet, triplet,
doublet of doublets, doublet of doublets of doublets, multiplet,
doublet of triplets, quadruplet and septet, respectively. All coupling
constants (J) are given in hertz (Hz).
Melting points (mp) were measured in open capillaries on a
Stuart Scientific SMP3 apparatus and are uncorrected.
A mass spectra ESI was recorded on a TSQ Quantum (Thermo
Finnigan) instrument.
solid). 1H NMR (CD3COCD3)
d 11.46e11.04 (m, 1H), 8.56e8.50 (m,
1H), 8.31 (dt, J ¼ 7.9, 1.1 Hz, 1H), 8.16 (dq, J ¼ 7.6, 1.1 Hz, 1H),
7.86e7.81 (m, 2H), 7.78e7.74 (m, 2H), 7.65 (d, J ¼ 3.8 Hz, 1H),

A.S. Abdelsamie et al. / European Journal of Medicinal Chemistry 82 (2014) 394e406
403
7.53e7.49 (m, 2H), 7.48e7.43 (m, 1H); 13C NMR (CD3COCD3)
7.10. (5-(3-Ethoxyphenyl)-thiophen-2-yl)-(3-isopropylamino-
phenyl)methanone (8)
d
187.54, 154.02, 142.71, 139.23, 137.47, 134.01, 133.85, 130.74,
130.22, 139.91, 127.10, 125.55; MS (ESI): 309.56 (M þ H)þ.
To a degassed mixture of 2-bromo-propane (123 mg, 1 mmol),
cupper II oxide (72 mg, 0.5 mmol) and potassium hydroxide (56 mg,
1 mmol) in DMF (1 ml) was slowly added (3-aminophenyl)-(5-(3-
ethoxyphenyl)-thiophen-2-yl)-methanone (6) (323 mg, 1 mmol).
The resulting mixture was heated at 135 ꢀC for 4 days, allowed to
cool to rt and poured into a 0 ꢀC 6 N HCl solution. After 15 min the
precipitate was filtered and washed with benzene. The filtrate was
extracted with benzene, dried over magnesium sulfate, filtered, and
concentrated to dryness. The product was purified by CC (hexane/
ethyl acetate 95:5); yield: 46% (168 mg; brownish oil). 1H NMR
7.5. (3-Aminophenyl)(5-bromothiophen-2-yl)methanone (6a)
A suspension of 6b (665 mg, 2 mmol) and tin(II)-chloride dihy-
drate (2388 mg, 11 mmol) in methanol (10 ml) was refluxed for 2 h.
The solvent was removed under vacuum and the residue was diluted
with saturated NaHCO3 and water. The suspension was extracted
with ethyl acetate. The combined extracts were washed with brine,
dried over magnesium sulfate, filtered and evaporated under
reduced pressure to give 6a (450 mg, 75%, brown solid, mp.102-4 ꢀC).
The product was sufficiently pure for use in the subsequent reaction.
(CDCl3)
d
7.63 (d, J ¼ 3.9 Hz, 1H), 7.32e7.28 (m, 2H), 7.26e7.22 (m,
2H), 7.20e7.17 (m, 1H), 7.15e7.11 (m, 1H), 7.04e7.01 (m, 1H), 6.89
(ddd, J ¼ 8.2, 2.5, 0.9 Hz, 1H), 6.76 (ddd, J ¼ 8.1, 2.5, 0.9 Hz, 1H), 4.07
(q, J ¼ 7.0 Hz, 2H), 3.67 (sept, J ¼ 12.4, 6.2 Hz, 2H), 1.43 (t, J ¼ 7.0 Hz,
7.6. General procedure for Suzuki coupling. Method B (6, 21a, 22a,
23b)
3H), 1.22 (d, J ¼ 6.3 Hz, 6H). 13C NMR (CDCl3)
d 188.75, 159.65,
A mixture of arylbromide (1 equiv), boronic acid derivative
(1.2 equiv), cesium carbonate (4 equiv) and tetrakis(-
triphenylphosphine) palladium (0.01 equiv) was suspended in an
oxygen-free DME/water (1:1) solution and refluxed under nitrogen
for 4 h. The reaction mixture was cooled to room temperature. The
aqueous layer was extracted with ethyl acetate. The combined
organic layers were washed with brine, dried over magnesium
sulfate, filtered and concentrated to dryness. The product was pu-
rified by CC.
153.00, 147.81, 142.72, 139.36, 135.92, 134.90, 130.36, 129.34, 124.11,
118.93, 118.10, 117.17, 115.31, 113.20, 112.67, 63.84, 44.43, 23.15,
15.03; MS (ESI): 366.62 (M þ H)þ.
7.11. 1-(3-(5-(3-Ethoxyphenyl)-thiophene-2-yl-carbonyl)-phenyl)-
3-methyl-thiourea (9)
A suspension of (3-amino-phenyl)-(5-(3-ethoxyphenyl)-thio-
phen-2-yl)-methanone (6) (205 mg, 0.6 mmol) and CH3NCS (46 mg,
0.6 mmol) in THF was refluxed overnight. The solution was cooled
and the product precipitated with heptane and purified by CC
(hexane/ethyl acetate 3:1) to give 9; yield: 56% (140 mg; yellow
7.7. (3-Amino-phenyl)(5-(3-ethoxy-phenyl)-thiophen-2-yl)
methanone (6)
solid; mp. 145-6 ꢀC). 1H NMR (CD3COCD3)
d 9.14 (br., 1H, NH), 8.14
The product was purified by CC (hexane/ethyl acetate 80:20);
(d, J ¼ 9.9 Hz, 1H), 7.87 (d, J ¼ 3.9 Hz, 1H), 7.70 (dd, J ¼ 6.2, 3.1 Hz,
1H), 7.64e7.61 (m,1H), 7.60 (d, J ¼ 4.0 Hz,1H), 7.51 (t, J ¼ 7.8 Hz,1H),
7.40e7.36 (m, 1H), 7.35 (dt, J ¼ 7.7, 1.5 Hz, 1H), 7.32e7.30 (m, 1H),
6.98 (ddd, J ¼ 7.8, 2.5, 1.4 Hz, 1H), 4.14 (q, J ¼ 7.0 Hz, 2H), 3.08 (d,
yield: 83% (570 mg; yellow solid). 1H NMR (CDCl3)
d 7.54 (d,
J ¼ 4.0 Hz, 1H), 7.26e7.22 (m, 2H), 7.18 (dd, J ¼ 1.6, 1.1 Hz, 1H),
7.18e7.14 (m, 2H), 7.13e7.11 (m, 1H), 7.07 (dd, J ¼ 2.1, 1.4 Hz, 1H),
6.83 (ddd, J ¼ 8.2, 2.5, 1.0 Hz, 1H), 6.80 (ddd, J ¼ 7.5, 2.4, 1.6 Hz, 1H),
4.01 (q, J ¼ 7.0 Hz, 2H), 3.78 (s, 2H), 1.37 (t, J ¼ 7.0 Hz, 3H); 13C NMR
J ¼ 4.6 Hz, 3H), 1.40 (t, J ¼ 7.0 Hz, 3H). 13C NMR (CD3COCD3)
d 188.17,
175.10, 159.37, 152.88, 146.62, 142.24, 139.09, 135.78, 135.36, 134.55,
130.10, 129.17, 123.87, 119.37, 118.67, 118.65, 115.06, 112.41, 63.57,
35.17, 14.75; MS (ESI): 397.89 (M þ H)þ.
(CDCl3)
d 188.17, 159.37, 152.88, 146.62, 142.24, 139.09, 135.78,
135.36, 134.55, 130.10, 129.17, 123.87, 119.37, 118.67, 118.65, 115.06,
112.41, 63.57, 14.75; MS (ESI): 324.00 (M þ H)þ.
7.12. (3-Benzylaminophenyl)-(5-(3-ethoxyphenyl)-thiophen-2-yl)-
7.8. General procedure for sulfonamide/amide coupling. Method C
methanone (10)
(7, 11e15)
The title compound was prepared by reaction of (3-amino-
The aminophenyl derivative (1 equiv) was dissolved in absolute
pyridine and was spiked with sulfonyl chloride/acid chloride
(1.5 equiv). The reaction mixture was stirred overnight at rt
(refluxed in case of amide coupling). The reaction was quenched by
adding 10 ml of 2 N HCl and extracted with ethyl acetate. The
organic layers were washed with saturated NaHCO3 and brine,
dried over magnesium sulfate, filtered and concentrated to dryness.
The product was purified by CC.
phenyl)-(5-(3-ethoxyphenyl)-thiophen-2-yl)-methanone
(6)
(135 mg, 0.42 mmol) and (bromomethyl)benzene (108 mg,
0.63 mmol) in acetone (10 ml). The resulting mixture was stirred at
rt for 10 h and poured into water. The precipitate was filtered and
purified by CC (hexane/ethyl acetate 97:3); yield: 42% (72 mg;
yellow oil). 1H NMR (CDCl3)
d
7.35 (d, J ¼ 4.0 Hz, 3H), 7.23 (tdd,
J ¼ 10.6, 9.0, 7.2 Hz, 14H), 7.18e7.14 (m, 6H), 7.13e7.11 (m, 7H),
7.08e7.05 (m, 6H), 6.96 (dd, J ¼ 2.2, 1.7 Hz, 3H), 6.78 (ddd, J ¼ 8.2,
2.5, 1.0 Hz, 3H), 6.71 (ddd, J ¼ 8.1, 2.5, 1.0 Hz, 3H), 4.25 (s, 7H), 3.96
7.9. N-(3-(5-(3-ethoxyphenyl)-thiophene-2-yl-carbonyl)-phenyl)-
C,C,C-trifluoro-methanesulfonamide (7)
(q, J ¼ 7.0 Hz, 6H), 1.32 (t, J ¼ 7.0 Hz, 9H); 13C NMR (CDCl3)
d 188.28,
159.34, 152.70, 147.94, 142.32, 138.91, 138.83, 135.70, 134.56, 130.06,
129.12, 128.66, 127.35, 127.27, 123.86, 118.63, 118.31, 116.67, 114.97,
112.76, 112.41, 63.54, 47.97, 14.74; MS (ESI): 414.81 (M þ H)þ.
The product was purified by CC (DCM); yield: 28% (60 mg;
yellow oil). 1H NMR (CDCl3)
d
7.76e7.72 (m, 1H), 7.67 (d, J ¼ 7.7 Hz,
1H), 7.56e7.49 (m, 2H), 7.41 (t, J ¼ 7.9 Hz, 1H), 7.22 (dd, J ¼ 15.2,
6.0 Hz, 2H), 7.14 (t, J ¼ 3.8 Hz, 1H), 7.11e7.05 (m, 1H), 6.85e6.77 (m,
1H), 3.98 (q, J ¼ 7.0 Hz, 2H), 1.33 (t, J ¼ 7.0 Hz, 3H); 13C NMR (CDCl3)
7.13. N-(3-(5-(3-ethoxy-phenyl)-thiophene-2-yl-carbonyl)-
phenyl)-isophthalamic acid (16)
d
187.28, 159.43, 154.79, 140.96, 139.04, 136.94, 135.09, 134.16,
A reaction of compound 15 (320 mg, 0.66 mmol) in ethanol
(5 ml) and 10% sodium hydroxide (15 ml) was refluxed in for 2 h on
a water bath. The reaction mixture was cooled, diluted with water
and neutralized with acetic acid. The crude product precipitated
130.24, 129.80, 127.58, 126.43, 124.37, 123.62, 121.08, 119.79 (d,
J ¼ 323.1 Hz) 118.78, 115.57, 112.50, 63.67, 14.75; MS (ESI): 455.84
(M þ H)þ.

404
A.S. Abdelsamie et al. / European Journal of Medicinal Chemistry 82 (2014) 394e406
and was purified by CC (hexane/ethyl acetate 1:3); yield: 80%
(250 mg; greenish-yellow solid; mp.
280 ꢀC). 1H NMR
(CD3COCD3) 10.06 (s, 1H, COOH), 8.69 (br. s, 1H, NH), 8.46 (s, 1H),
155.35,140.30, 135.85, 134.75, 132.40, 128.20, 127.05, 126.40, 121.05,
>
118.15, 111.00; MS (ESI): 303.35 (M þ H)þ.
d
8.21 (dd, J ¼ 37.3, 7.8 Hz, 3H), 7.81 (d, J ¼ 4.0 Hz, 1H), 7.69e7.53 (m,
7.18. 2-(3-Methoxybenzyl)-5-phenylthiophene (19a)
4H), 7.42e7.30 (m, 3H), 7.02e6.94 (m, 1H), 4.15 (q, J ¼ 7.0 Hz, 2H),
1.40 (t, J ¼ 7.0 Hz, 3H); 13C NMR (CD3COCD3)
d
187.63, 165.96,
(3-Methoxyphenyl)(5-phenylthiophen-2-yl)methanone (17c)
(300 mg, 1.01 mmol, 1 equiv) was dissolved in 20 ml acetic acid, tin
(II) chloride dihydrate (1.16 mg, 5.20 mmol, 5.20 equiv) was added
in 3.33 ml hydrogen chloride and the mixture was refluxed over-
night. The mixture was cooled to room temperature, quenched
with water, extracted two times with dichloromethane, dried and
evaporated under reduced pressure. The crude product was puri-
fied by CC (hexane/ethyl acetate 9:1); yield: 50% (147 mg, white oil).
160.63, 153.48, 143.10, 140.31, 139.25, 137.15, 135.39, 133.71, 133.69,
133.67, 133.66, 132.79, 132.76, 132.72, 131.27, 129.97, 129.65, 125.69,
125.18, 121.73, 119.35, 116.28, 112.89, 64.28, 15.07; MS (ESI): 472.92
(M þ H)þ.
7.14. (3-Methoxyphenyl)-(5-phenylthiophen-2-yl)-methanethione
(17b)
1H NMR (CD3COCD3)
d 7.54e7.61 (m, 2H), 7.32e7.40 (m, 2H),
(3-methoxyphenyl)(5-phenylthiophen-2-yl)methanone (17c)
(300 mg, 1.02 mmol, 1.00 equiv) was dissolved under nitrogen in
20 ml abs. toluene and Lawesson's reagent was added. The mixture
was stirred for 2 h under reflux and concentrated under reduced
pressure. Purification by column chromatography (hexane: ethyl
acetate 9:1); yield: 96% (300 mg; dark green oil); Used in the next
step without any characterization.
7.19e7.28 (m, 3H), 6.87e6.92 (m, 3H), 6.75e6.83 (m, 1H), 4.15 (s,
2H), 3.78 (s, 3H).
7.19. 2-(1-(3-Methoxyphenyl)vinyl)-5-phenylthiophene (20a)
Methyltriphenylphosphonium bromide (364 mg, 1.01 mmol,
1 equiv) was suspended in 5 ml dry tetrahydrofuran, n-butyllithium
(400
ml, 2.5 M in hexane) was added dropwise, stirred at room
7.15. 2-(Difluoro(3-methoxyphenyl)methyl)-5-phenylthiophene
(17a)
temperature for 90 min, (3-methoxyphenyl)(5-phenylthiophen-2-
yl)methanone (17c) (300 mg, 1.01 mmol, 1.00 equiv), previously
solubilized in 2 ml dry tetrahydrofuran, was added dropwise and
stirred at room temperature for 1 h, then at 65 ꢀC overnight. The
mixture was cooled to room temperature, quenched with water
and extracted two times with ethyl acetate. The combined organic
layers were washed one time with water, dried and evaporated
under reduced pressure. The crude product was purified by CC
(hexane/ethyl acetate 9:1); yield: 35% (105 mg, yellow oil). 1H NMR
Under N2 (3-methoxyphenyl)(5-phenylthiophen-2-yl)meth-
anethione) (17b) (100 mg, 0.34 mmol, 1 equiv) was placed in a
100 ml teflon flask and dissolved under nitrogen in 3 ml abs.
dichloromethane. Diethylaminosulfur trifluoride (DAST, 167
ml,
1.36 mmol, 3 equiv) to the solution was added slowly at room
temperature and the mixture was stirred for 3 h. The reaction was
carefully quenched with cold sat. Sodium hydrogen carbonate and
extracted three times with diethyl ether. The combined organic
layers were washed two times with sat. Sodium hydrogen car-
bonate, one time with water, one time with brine, dried over
magnesium sulfate, filtered and concentrated under reduced
pressure. The crude product was purified by CC (hexane/ethyl ac-
etate 85:15); yield: 63% (68 mg, red viscous oil). 1H NMR
(CD3COCD3)
d
7.68 (d, J ¼ 8.2 Hz, 2H), 7.40e7.45 (m, 2H), 7.38 (d,
J ¼ 3.8 Hz, 1H), 7.29e7.36 (m, 2H), 7.01e7.06 (m, 2H), 6.94e7.00 (m,
2H), 5.64 (d, J ¼ 1.5 Hz, 1H), 5.29 (d, J ¼ 1.5 Hz, 1H), 3.83 (s, 3H).
7.20. General procedure for the synthesis of compounds 23c, 23a,
24a
(CD3COCD3)
2H), 7.23e7.19 (m, 1H), 7.18e7.13 (m, 2H), 7.13e7.10 (m, 1H), 3.87 (s,
3H); 13C NMR (CD3COCD3)
187.70, 160.70, 153.45, 143.15, 140.35,
d
7.71e7.67 (m, 2H), 7.49e7.42 (m, 3H), 7.41e7.35 (m,
The intermediates (23d or 23b, 1 equiv) were dissolved in 40 ml
acetone under nitrogen. Cesium carbonate (2.10 equiv) and benzyl-
or alkyliodide (1.5 equiv) were added and the mixture was stirred at
room temperature overnight. The reaction was quenched with
water. The combined organic layers were washed one time with
water, one time with sat. Sodium hydrogen carbonate, one time
with brine, dried over sodium sulfate, filtered and concentrated
under vacuum.
d
137.05, 134.10, 130.55, 130.10, 127.15, 125.50, 122.10, 119.15, 114.50,
55.80; MS (ESI): 317.40 (M þ H)þ.
7.16. General procedure for ether cleavage. Method D (17e25, 23d,
27)
To a solution of ether derivative (1 equiv) in anhydrous
dichloromethane at ꢁ78 ꢀC (dry ice/acetone bath), boron tri-
bromide in dichloromethane (1 M, 3 equiv per methoxy function)
-boron trichloride in dichloromethane (1 M, 2 equiv) in case of 23
and 24- was added dropwise. The reaction mixture was stirred
overnight at room temperature under nitrogen atmosphere. Water
was added to quench the reaction, and the aqueous layer was
extracted with dichloromethane. The combined organic layers
were washed with brine, dried over magnesium sulfate, filtered,
and concentrated to dryness. The product was purified by CC.
7.21. (3-(Benzyloxy)phenyl)(5-bromothiophen-2-yl)methanone
(23c)
The crude product was recrystallized in hexane/acetone (99:1);
yield: 50% (6.9 g, white solid). 1H NMR (CD3COCD3)
d
7.46 (t,
J ¼ 8.2 Hz, 3H), 7.41e7.36 (m, 5H), 7.33e7.27 (m, 3H), 5.21 (s, 2H);
13C NMR (CD3COCD3)
186.80, 159.75, 146.15, 139.45, 128.05,
d
136.50, 132.95, 130.80, 129.45, 128.85, 128.45, 123.00, 122.30,
120.65, 115.55, 70.40; MS (ESI): 373.0 (M þ H)þ.
7.22. General procedure for the synthesis of compounds 25a, 27a
7.17. 3-(Difluoro(5-phenylthiophen-2-yl)methyl)phenol (17)
3-Methoxybenzenethiol (111 mg,1.0 mmol) was slowly added to
a degassed mixture of the brominated intermediate (21b or 27b;
300 mg, 1.0 mmol), copper(I)-oxide (72 mg, 0.5 mmol) and potas-
sium hydroxide (56 mg, 1.0 mmol) in dimethylformamide (1 ml).
The resulting mixture was heated at 135 ꢀC for 3 h, allowed to cool
to rt and poured into an ice-cooled 6 NeHCl solution. After 15 min
The product was purified by CC (hexane: ethyl acetate 8:2)
followed by preparative TLC (hexane : ethyl acetate 7:3); yield 14%
(13 mg; dark green oil). 1H NMR (CD3COCD3)
d
7.87e7.85 (m, 1H),
7.52e7.48 (m, 4H), 7.37e7.34 (m, 2H), 7.21e7.17 (m, 1H), 7.15e7.13
(m, 1H), 7.09e7.00 (m, 2H); 13C NMR (CD3COCD3)
189.55, 168.80,
d

A.S. Abdelsamie et al. / European Journal of Medicinal Chemistry 82 (2014) 394e406
405
the precipitate was filtered and washed with benzene. The filtrate
was extracted with benzene, dried over magnesium sulfate,
filtered, and concentrated under reduced pressure.
number A/09/92319). Thanks are also due to Jessica Hilschmann for
her support in the synthetic work.
Appendix A. Supplementary data
7.23. 3-(Methoxyphenyl)-(5-(3-methoxyphenyl)sulfanyl-thiophen-
2-yl)-methanone (25a)
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.ejmech.2014.05.074.
The product was purified by CC (hexane/ethyl acetate 97:3);
yield 75% (270 mg; yellow oil). 1H NMR (CDCl3)
d
7.65 (d, J ¼ 3.9 Hz,
References
1H), 7.54e7.47 (m, 2H), 7.46 (dd, J ¼ 2.4, 1.4 Hz, 1H), 7.39e7.36 (m,
1H), 7.26e7.21 (m, 2H), 7.13 (ddd, J ¼ 7.7, 1.7, 0.9 Hz, 1H), 7.10e7.07
(m, 1H), 6.95 (ddd, J ¼ 8.3, 2.5, 0.8 Hz, 1H), 3.97 (s, 3H), 3.90 (s, 3H);
[1] M. Ferin, P.E. Zimmering, S. Lieberman, R.L. Vande Wiele, Inactivation of the
biological effects of exogenous and endogenous estrogens by antibodies to 17-
beta-estradiol, Endocrinology 83 (1968) 565e571.
[2] J.G. Liehr, Is estradiol a genotoxic mutagenic carcinogen? Endocr. Rev. 21
(2000) 40e54.
[3] J.M. Hall, J.F. Couse, K.S. Korach, The multifaceted mechanisms of estradiol and
estrogen receptor signaling, J. Biol. Chem. 276 (2001) 36869e36872.
[4] D.B. Thomas, Do hormones cause breast cancer? Cancer 53 (1984) 595e604.
[5] J. Russo, S.V. Fernandez, P.A. Russo, R. Fernbaugh, F.S. Sheriff, H.M. Lareef,
J. Garber, I.H. Russo, 17-Beta-estradiol induces transformation and tumori-
genesis in human breast epithelial cells, FASEB J. 20 (2006) 1622e1634.
[6] G.S. Dizerega, D.L. Barber, G.D. Hodgen, Endometriosis: role of ovarian steroids
in initiation, maintenance, and suppression, Fertil. Steril. 33 (1980) 649e653.
[7] K. Zeitoun, K. Takayama, H. Sasano, T. Suzuki, N. Moghrabi, S. Andersson,
A. Johns, L. Meng, M. Putman, B. Carr, S.E. Bulun, Deficient 17beta-hydrox-
13C NMR (CDCl3)
d 186.88, 160.17, 159.61, 145.61, 145.27, 138.98,
136.07, 135.10, 131.94, 130.24, 129.40, 122.77, 121.55, 118.61, 116.00,
113.77, 113.66, 55.42, 55.33; MS (ESI): 357.25 (M þ H)þ.
7.24. General procedure for the synthesis of compounds 26, 28
The title compounds were prepared by reaction of the respec-
tive thioether (25 or 27; 100 mg, 0.30 mmol) and H2O2 (30%, 0.1 ml)
in acetic acid (2 ml). The solution was allowed to stand at rt for 4
days and was then poured into water. The solid was filtered off,
washed with water and dried.
ysteroid dehydrogenase type
2 expression in endometriosis: failure to
metabolize 17beta-estradiol, J. Clin. Endocrinol. Metab. 83 (1998) 4474e4480.
[8] A. Purohit, P.A. Foster, Steroid sulfatase inhibitors for estrogen- and androgen-
dependent cancers, J. Endocrinol. 212 (2012) 99e110.
[9] F. Picard, E. Baston, W. Reichert, R.W. Hartmann, Synthesis of N-substituted
piperidine-4-(benzylidene-4-carboxylic acids) and evaluation as inhibitors of
7.25. (5-(3-Hydroxybenzenesulfonyl)-thiophen-2-yl)-(3-
hydroxyphenyl)methanone (26)
steroid-5alpha-reductase type
1
and 2, Bioorg Med. Chem.
8
(2000)
1479e1487.
The product was purified by CC (Dichloromethane/methanol
€
99:1); yield 64% (70 mg, yellow solid, mp. 102 ꢀC). 1H NMR (CD3OD)
d
[10] C. Gunnarsson, M. Ahnstrom, K. Kirschner, B. Olsson, B. Nordenskjold,
L.E. Rutqvist, L. Skoog, O. Stal, Amplification of HSD17B1 and ERBB2 in primary
breast cancer, Oncogene 22 (2003) 34e40.
[11] V. Speirs, A.R. Green, S.L. Atkin, Activity and gene expression of 17beta-
hydroxysteroid dehydrogenase type I in primary cultures of epithelial and
stromal cells derived from normal and tumourous human breast tissue: the
role of IL-8, J. Steroid Biochem Mol. Biol. 67 (1998) 267e274.
7.72 (d, J ¼ 4.0 Hz, 1H), 7.61 (d, J ¼ 4.0 Hz, 1H), 7.49e7.44 (m, 1H),
7.44e7.38 (m, 2H), 7.33 (t, J ¼ 7.8 Hz, 1H), 7.27 (d, J ¼ 7.7 Hz, 1H),
7.24e7.20 (m, 1H), 7.07 (dddd, J ¼ 5.0, 3.7, 2.5, 0.9 Hz, 2H); 13C NMR
(CD3OD)
d 188.96, 159.83, 159.03, 151.00, 150.83, 143.33, 139.20,
135.32, 134.36, 132.05, 130.97, 122.40, 121.66, 121.56, 119.45, 116.63,
[12] T. Suzuki, T. Moriya, N. Ariga, C. Kaneko, M. Kanazawa, H. Sasano, 17betahy-
droxysteroid dehydrogenase type 1 and type 2 in human breast carcinoma: a
correlation to clinicopathological parameters, Br. J. Cancer 82 (2000)
518e523.
[13] T. Smuc, N. Hevir, M. Ribic-Pucelj, B. Husen, H. Thole, T.L. Rizner, Disturbed
estrogen and progesterone action in ovarian endometriosis, Mol. Cell. Endo-
crinol. 301 (2009) 59e64.
[14] B. Husen, K. Huhtinen, M. Poutanen, L. Kangas, J. Messinger, H. Thole, Evalu-
ation of inhibitors for 17beta-hydroxysteroid dehydrogenase type 1 in vivo in
immunodeficient mice inoculated with MCF-7 cells stably expressing the
recombinant human enzyme, Mol. Cell. Endocrinol. 248 (2006) 109e113.
[15] B. Husen, K. Huhtinen, T. Saloniemi, J. Messinger, H.H. Thole, M. Poutanen,
Human hydroxysteroid (17-beta) dehydrogenase 1 expression enhances es-
trogen sensitivity of MCF-7 breast cancer cell xenografts, Endocrinology 147
(2006) 5333e5339.
114.92. MS (ESI): 362.23 (M þ H)þ.
ꢀ
ꢀ
7.26. Biological methods
[2,4,6,7-3H]-E1 and [2,4,6,7-3H]-E2 were bought from Per-
kineElmer, Boston. Quickszint Flow 302 scintillator fluid was
bought from Zinsser Analytic, Frankfurt. For a brief description of
the biological assays see Supporting Data.
7.27. Molecular modeling
[16] J.M. Day, P.A. Foster, H.J. Tutill, M.F. Parsons, S.P. Newman, S.K. Chander,
G.M. Allan, H.R. Lawrence, N. Vicker, B.V. Potter, M.J. Reed, A. Purohit, 17beta-
hydroxysteroid dehydrogenase type 1, and not type 12, is a target for endo-
crine therapy of hormone-dependent breast cancer, Int. J. Cancer 122 (2008)
1931e1940.
Local docking experiments followed by an energy minimization
step were performed with YASARA structure using the AMBER03
force field [47,48]. Protein coordinates were prepared starting from
[17] P. Kruchten, R. Werth, E. Bey, A. Oster, S. Marchais-Oberwinkler, M. Frotscher,
R.W. Hartmann, Selective inhibition of 17beta-hydroxysteroid dehydrogenase
type 1 (17betaHSD1) reduces estrogen responsive cell growth of T47-D breast
cancer cells, J. Steroid Biochem Mol. Biol. 114 (2009) 200e206.
a crystal structure of human 17b-HSD1 in complex with estradiol
and NADPþ (PDB ID: 1FDT) [49]. After removal of ligand atoms, a
grid box of approximately 7.5 nm3 was set up around the active site
of the enzyme. The flexible local docking experiment using the
built-in AutoDock 4 algorithm and 999 docking runs was per-
formed with energy-minimized manual models of inhibitors 25
and 26 [50]. Highest-ranked enzymeeinhibitor complexes were
subjected to an energy minimization step with fixed protein
backbone atoms. Ligand-protein interactions of the yielded struc-
tures were analyzed with MOE 2010.
€
[18] G. Moller, D. Deluca, C. Gege, A. Rosinus, D. Kowalik, O. Peters, P. Droescher,
W. Elger, J. Adamski, A. Hillisch, Structure-based design, synthesis and in vitro
characterization of potent 17b-hydroxysteroid dehydrogenase type 1 in-
hibitors based on 2-substitutions of estrone and D-homo-estrone, Bioorg.
Med. Chem. Lett. 19 (2009) 6740e6744.
[19] D. Poirier, Advances in development of inhibitors of 17beta hydroxysteroid
dehydrogenases, Anticancer Ag. Med. Chem. 9 (2009) 642e660.
[20] E. Bey, S. Marchais-Oberwinkler, P. Kruchten, M. Frotscher, R. Werth, A. Oster,
O. Algül, A. Neugebauer, R.W. Hartmann, Design, synthesis and biological
evaluation of bis(hydroxyphenyl) azoles as potent and selective non-steroidal
inhibitors of 17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD1) for
the treatment of estrogen-dependent diseases, Bioorg Med. Chem. 16 (2008)
6423e6435.
Acknowledgment
[21] E. Bey, S. Marchais-Oberwinkler, M. Negri, P. Kruchten, A. Oster, T. Klein,
A. Spadaro, R. Werth, M. Frotscher, B. Birk, R.W. Hartmann, New insights into
the SAR and binding modes of bis(hydroxyphenyl)thiophenes and -benzenes:
influence of additional substituents on 17beta-hydroxysteroid dehydrogenase
We are grateful to the Egyptian Ministry of Higher Education
and Scientific Research (MoHESR) and the Deutscher Akademischer
Austausch Dienst (DAAD) for financial support of this work (grant

406
A.S. Abdelsamie et al. / European Journal of Medicinal Chemistry 82 (2014) 394e406
type 1 (17beta-HSD1) inhibitory activity and selectivity, J. Med. Chem. 52
(2009) 6724e6743.
[35] J.C. Meslin, Y.T. N'Guessan, H. Quiniou, F. Tonnard, Enchainements hetero-
^
atomiques et leurs produits de cyclisationaeI: Vinylogues de thioamides
[22] A. Oster, T. Klein, R. Werth, P. Kruchten, E. Bey, M. Negri, S. Marchais-
Oberwinkler, M. Frotscher, R.W. Hartmann, Novel estrone mimetics with
high 17beta-HSD1 inhibitory activity, Bioorg Med. Chem. 18 (2010)
3494e3505.
comme intermediaires de synthese d'acyl-2 thiophenes, thio-1 pyrannones-2
(thiones), dihydro-5,6 dithiinnes-1,2 dioxydes-1,1 et dithiinnes-1,2 dioxydes-
1,1 substitues, Tetrahedron 31 (1975) 2679e2684.
[36] C.-M. Liu, B.-H. Chen, W.-Y. Liu, X.-L. Wu, Y.-X. Ma, Conversion of tributyl-
stannylferrocene to a variety of heteroaryl ferrocenes, J. Organomet. Chem.
598 (2000) 348e352.
[37] G.S. Lal, E. Lobach, A. Evans, Fluorination of thiocarbonyl compounds with
Bis(2-methoxyethyl)aminosulfur trifluoride (Deoxo-fluor reagent): a facile
synthesis of gem-difluorides, J. Org. Chem. 65 (2000) 4830e4832.
[38] B.E. Fink, D.S. Mortensen, S.R. Stauffer, Z.D. Aron, J.A. Katzenellenbogen, Novel
structural templates for estrogen-receptor ligands and prospects for combi-
natorial synthesis of estrogens, Chem. Biol. 6 (1999) 205e219.
[39] P. Kruchten, R. Werth, S. Marchais-Oberwinkler, M. Frotscher, R.W. Hartmann,
Development of a biological screening system for the evaluation of highly
active and selective 17beta-HSD1-inhibitors as potential therapeutic agents,
Mol. Cell. Endocrinol. 301 (2009) 154e157.
[23] G.M. Allan, N. Vicker, H.R. Lawrence, H.J. Tutill, J.M. Day, M. Huchet,
E. Ferrandis, M.J. Reed, A. Purohit, B.V. Potter, Novel inhibitors of 17beta-
hydroxysteroid dehydrogenase type 1: templates for design, Bioorg Med.
Chem. 16 (2008) 4438e4456.
ꢀ ꢀ
[24] P. Brozic, P. Kocbek, M. Sova, J. Kristl, S. Martens, J. Adamski, S. Gobec,
ꢀ
ꢀ
T. Lanisnik Rizner, Flavonoids and cinnamic acid derivatives as inhibitors of
17beta-hydroxysteroid dehydrogenase type 1, Mol. Cell. Endocrinol. 301
(2009) 229e234.
€
€ €
[25] S. Karkola, A. Lilienkampf, K. Wahala, A 3D QSAR model of 17beta-HSD1 in-
hibitors based on a thieno[2,3-d]pyrimidin-4(3H)-one core applying molec-
ular dynamics simulations and ligand-protein docking, ChemMedChem 3
(2008) 461e472.
[26] A. Lilienkampf, S. Karkola, S. Alho-Richmond, P. Koskimies, N. Johansson,
K. Huhtinen, K. Vihko, K. Wahala, Synthesis and biological evaluation of
17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD1) inhibitors based
[40] W. Qiu, R.L. Campbell, A. Gangloff, P. Dupuis, R.P. Boivin, M.R. Tremblay,
D. Poirier, S.X. Lin, A concerted, rational design of type 1 17beta-hydrox-
ysteroid dehydrogenase inhibitors: estradiol-adenosine hybrids with high
affinity, FASEB J. 16 (2002) 1829e1831.
on
a thieno[2,3-d]pyrimidin-4(3H)-one core, J. Med. Chem. 52 (2009)
6660e6671.
[41] K.M. Sam, S. Auger, V. Luu-The, D. Poirier, Steroidal spiro-gamma-lactones
that inhibit 17 beta-hydroxysteroid dehydrogenase activity in human
placental microsomes, J. Med. Chem. 38 (1995) 4518e4528.
[27] D. Schuster, L.G. Nashev, J. Kirchmair, C. Laggner, G. Wolber, T. Langer,
A. Odermatt, Discovery of nonsteroidal 17beta-hydroxysteroid dehydroge-
nase 1 inhibitors by pharmacophore-based screening of virtual compound
libraries, J. Med. Chem. 51 (2008) 4188e4199.
[42] P.N. Craig, Interdependence between physical parameters and selection of
substituent groups for correlation studies, J. Med. Chem. 14 (1971) 680e684.
[43] T. Klein, C. Henn, M. Negri, M. Frotscher, Structural basis for species specific
inhibition of 17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD1):
computational study and biological validation, PLoS One 6 (2011) e22990.
[44] R. Wilcken, M.O. Zimmermann, A. Lange, A.C. Joerger, F.M. Boeckler, Principles
and applications of halogen bonding in medicinal chemistry and chemical
biology, J. Med. Chem. 56 (2013) 1363e1388.
ꢀ
ꢁ
ꢀ ꢀ
ꢀ
[28] S. Starcevic, P. Brozic, S. Turk, J. Cesar, T.L. Rizner, S. Gobec, Synthesis and
biological evaluation of (6- and 7-phenyl) coumarin derivatives as selective
nonsteroidal inhibitors of 17beta-hydroxysteroid dehydrogenase type 1,
J. Med. Chem. 54 (2011) 248e261.
ꢀ
ꢁ
ꢀ
ꢀ
[29] S. Starcevic, S. Turk, B. Brus, J. Cesar, T. Lanisnik Rizner, S. Gobec, Discovery of
highly potent, nonsteroidal 17beta-hydroxysteroid dehydrogenase type
1
inhibitors by virtual high-throughput screening, J. Steroid Biochem Mol. Biol.
127 (2011) 255e261.
[45] M. Frotscher, E. Ziegler, S. Marchais-Oberwinkler, P. Kruchten, A. Neugebauer,
L. Fetzer, C. Scherer, U. Muller-Vieira, J. Messinger, H. Thole, R.W. Hartmann,
Design, synthesis, and biological evaluation of (hydroxyphenyl)naphthalene
and -quinoline derivatives: potent and selective nonsteroidal inhibitors of
17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD1) for the treat-
ment of estrogen-dependent diseases, J. Med. Chem. 51 (2008) 2158e2169.
[46] B.E. Smart, Fluorine substituent effects (on bioactivity), J. Fluor. Chem. 109
(2001) 3e11.
[47] Y. Duan, C. Wu, S. Chowdhury, M.C. Lee, G. Xiong, W. Zhang, R. Yang,
P. Cieplak, R. Luo, T. Lee, J. Caldwell, J. Wang, P. Kollman, A point-charge force
field for molecular mechanics simulations of proteins based on condensed-
phase quantum mechanical calculations, J. Comput Chem. 24 (2003)
1999e2012.
[48] E. Krieger, T. Darden, S.B. Nabuurs, A. Finkelstein, G. Vriend, Making optimal
use of empirical energy functions: force-field parameterization in crystal
space, Proteins 57 (2004) 678e683.
[49] R. Breton, D. Housset, C. Mazza, J.C. Fontecilla-Camps, The structure of a
complex of human 17beta-hydroxysteroid dehydrogenase with estradiol and
NADPþ identifies two principal targets for the design of inhibitors, Structure 4
(1996) 905e915.
[30] A. Oster, T. Klein, C. Henn, R. Werth, S. Marchais-Oberwinkler, M. Frotscher,
R.W. Hartmann, Bicyclic substituted hydroxyphenylmethanone type in-
hibitors of 17 beta-hydroxysteroid dehydrogenase Type 1 (17 beta-HSD1): the
role of the bicyclic moiety, ChemMedChem 6 (2011) 476e487.
[31] E. Bey, S. Marchais-Oberwinkler, R. Werth, M. Negri, Y.A. Al-Soud, P. Kruchten,
A. Oster, M. Frotscher, B. Birk, R.W. Hartmann, Design, synthesis, biological
evaluation and pharmacokinetics of bis(hydroxyphenyl) substituted azoles,
thiophenes, benzenes, and aza-benzenes as potent and selective nonsteroidal
inhibitors of 17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD1),
J. Med. Chem. 51 (2008) 6725e6739.
[32] A. Oster, S. Hinsberger, R. Werth, S. Marchais-Oberwinkler, M. Frotscher,
R.W. Hartmann, Bicyclic substituted hydroxyphenylmethanones as novel in-
hibitors of 17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD1) for
the treatment of estrogen-dependent diseases, J. Med. Chem. 53 (2010)
8176e8186.
[33] N. Miyaura, T. Yanagi, A. Suzuki, The palladium-catalyzed cross-coupling re-
action of phenylboronic acid with haloarenes in the presence of bases, Synth.
Commun. 11 (1981) 513e519.
[34] L.-C. Liang, P.-S. Chien, M.-H. Huang, Catalytic suzuki coupling reactions by
amido phosphine complexes of palladium, Organometallics 24 (2005)
353e357.
[50] G.M. Morris, R. Huey, W. Lindstrom, M.F. Sanner, R.K. Belew, D.S. Goodsell,
A.J. Olson, AutoDock4 and AutoDockTools4: automated docking with selective
receptor flexibility, J. Comput. Chem. 30 (2009) 2785e2791.