Synthesis and SAR of thiazolidinedione derivatives as 15-PGDH inhibitors

Article abstract of DOI:10.1016/j.bmc.2010.01.016

Prostaglandins have a short life in vivo because they are metabolized rapidly by oxidation to 15-ketoprostaglandins catalyzed by a cytosolic enzyme known as NAD⁺-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH). Previously, CT-8, a thiazolidinedione analogue, was found to be a potent inhibitor of 15-PGDH. Structure-activity analysis indicated that the N-methylation of thiazolidine-2,4-dione, CT-8, abolished the inhibitory activity, whereas the introduction of an ethyl hydroxyl group at amine in CT-8 still had a good inhibitory effect. Based on the structures of the thiazolidinediones analogues and inhibitory activity, a range of benzylidene thiazolidinedione derivatives were synthesized with different substituents on the phenyl ring and their inhibitory activity was evaluated. Replacement of the cyclohexylethyl group of CT-8 with the hetero five-member ring increased the inhibitory potency. However, replacement of the cyclohexylethyl group with a hetero six-member ring decreased the inhibitory potency significantly. It was found that compound 2 (5-(4-(2-(thiophen-2-yl)ethoxy)benzylidene)thiazolidine-2,4-dione) was the most potent inhibitor that was effective in the nanomolar range.

Full text of DOI:10.1016/j.bmc.2010.01.016

Bioorganic & Medicinal Chemistry 18 (2010) 1428–1433
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Synthesis and SAR of thiazolidinedione derivatives as 15-PGDH inhibitors
Ying Wu a, Hsin-Hsiung Tai b, Hoon Cho a,c,
*
a Department of Polymer Science & Engineering, Chosun University, Gwangju 501-759, Republic of Korea
b Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA
c Research Center for Resistant Cells, Chosun University, Gwangju 501-759, Republic of Korea
a r t i c l e i n f o
a b s t r a c t
Article history:
Prostaglandins have a short life in vivo because they are metabolized rapidly by oxidation to 15-keto-
prostaglandins catalyzed by a cytosolic enzyme known as NAD+-dependent 15-hydroxyprostaglandin
dehydrogenase (15-PGDH). Previously, CT-8, a thiazolidinedione analogue, was found to be a potent
inhibitor of 15-PGDH. Structure–activity analysis indicated that the N-methylation of thiazolidine-
2,4-dione, CT-8, abolished the inhibitory activity, whereas the introduction of an ethyl hydroxyl group
at amine in CT-8 still had a good inhibitory effect. Based on the structures of the thiazolidinediones
analogues and inhibitory activity, a range of benzylidene thiazolidinedione derivatives were synthe-
sized with different substituents on the phenyl ring and their inhibitory activity was evaluated.
Replacement of the cyclohexylethyl group of CT-8 with the hetero five-member ring increased the
inhibitory potency. However, replacement of the cyclohexylethyl group with a hetero six-member ring
decreased the inhibitory potency significantly. It was found that compound 2 (5-(4-(2-(thiophen-2-
yl)ethoxy)benzylidene)thiazolidine-2,4-dione) was the most potent inhibitor that was effective in
the nanomolar range.
Received 19 December 2009
Revised 6 January 2010
Accepted 7 January 2010
Available online 11 January 2010
Keywords:
Thiazolidinediones
15-PGDH
Ulcer healing
Wound healing
Bone formation
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
ies on the prostaglandin catabolism have focused on the Type I en-
zyme (hereafter referred to as 15-PGDH).
Prostaglandins are derived from arachidonic acid through the
cyclooxygenase (COX) pathway. Two COX isoforms have been rec-
ognized. COX-1 is expressed constitutively in various tissues,
including the stomach, whereas COX-2 is induced by cytokines,
growth factors, tumor promoters and other agents. Prostaglandins
have a short life time in vivo because they are metabolized rapidly
by oxidation to 15-ketoprostaglandins catalyzed by a cytosolic en-
zyme named NAD+-dependent 15-hydroxyprostaglandin dehydro-
genase (15-PGDH).1 This enzyme is present ubiquitously in
mammalian tissues and is responsible for the biological inactiva-
tion of prostaglandins because 15-ketoprostaglandins possess sig-
nificantly lower biological activities.2 Two different types of 15-
PGDH have been recognized. Type I is NAD+ specific, while Type
II is NADP+ preferred. Type I is more prostaglandin specific and
exhibits a low Km for prostaglandins, whereas Type II has a much
broader substrate specificity and shows a high Km for prostaglan-
dins.3 Indeed, Type II was later found to be identical to carbonyl
reductase.4 Therefore, Type I is considered to be the key enzyme
responsible for the biological inactivation of prostaglandins. Stud-
Prostaglandins have been implicated in a wide variety of phys-
iological and pathological processes. Prostaglandin E2 (PGE2) is a
major mediator of inflammation and a key player in the control
of various physiological functions. Recently, clinical studies dem-
onstrated that PGE2 causes the growth of body hair and eyelashes
in humans and animals.5 In humans, trials carried out on the scalp
have shown that PGE2 could increase the hair density.6 Further-
more, 15-PGDH is also expressed in hair melanocytes. Inhibition
of this enzyme as a target to reduce hair loss has been reported.7
PGE2 has also been identified as an important mediator of gastric
ulcer healing,8–16 bone formation,17–21 and dermal wound heal-
ing.22–27 Therefore, inhibitors of 15-PGDH will be valuable for the
therapeutic management of such disorders.
Previously, it was reported that ciglitazone, an antidiabetic thia-
zolidinedione, is a potent antagonist of the 15-PGDH enzymatic
activity with an IC50 of 2.7
l
M.28 In addition, the inhibitory po-
tency of ciglitazone was higher than those of other thiazolidinedi-
ones, such as rosiglitazone (10 times) and troglitazone (127 times)
(Fig. 1). Structure–activity analysis of thiazolidinediones also indi-
cated that the nature of the moiety linking to benzylidenethiazoli-
dine-2,4-dione through an ether linkage plays an important role in
its inhibitory potency.29 Based on the structures of the thiazolidin-
ediones analogues and inhibitory activity, various benzylidene
thiazolidinedione derivatives with different substituents on the
Abbreviations: 15-PGDH, NAD+-dependent 15-hydroxyprostaglandin dehydro-
genase; DTT, dithiothreitol; SDS, sodium dodecylsulfate; EDTA, ethylenediamine-
N,N,N0,N0-tetraacetic acid; GST, glutathione S-transferase; THF, tetrahydrofuran.
* Corresponding author. Tel.: +82 62 230 7635; fax: +82 62 230 2474.
E-mail address: hcho@chosun.ac.kr (H. Cho).
0968-0896/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2010.01.016

Y. Wu et al. / Bioorg. Med. Chem. 18 (2010) 1428–1433
1429
O
O
CH3
HO
NH
S
NH
S
O
O
H3C
O
CH3
O
O
O
CH3
Ciglitazone
Troglitazone
O
NH
NH
N
N
S
S
O
O
O
O
Rosiglitazone
CT-8
Figure 1. Structures of ciglitazone, rosiglitazone, troglitazone, and CT-8.
phenyl ring were synthesized using a series of reactions and tested
for the 15-PGDH inhibitory activity.
with thiazolidine-2,4-dione to afford the appropriate thiazoli-
dine-2,4-dione derivatives. All the synthesized compounds were
assayed in vitro against 15-PGDH. Table 1 lists their inhibitory
activities (IC50 values).
2. Results and discussion
Previously, it was reported that ciglitazone and its derivatives
are potent inhibitors of 15-PGDH. This indicates that the benzyl-
idene thiazolidine-2,4-dione analog showed significantly higher
inhibitory potency than the benzyl thiazolidine-2,4-dione analog.
It was also interesting to discover that the amine group of thia-
zolidine-2,4-dione plays an important role in the inhibitory po-
tency. This was further confirmed by the synthesis of another
N-methylated derivative (compound 29), in which protection of
the amine group in the molecule by methylation rendered the
compound totally inactive. In order to demonstrate the role of
the amine group in the molecule, an ethyl hydroxyl group was
introduced instead of hydrogen and the inhibitory potency of
the compounds was compared. Interestingly, the introduction
of an ethyl hydroxyl group at the amine group in CT-8 still pro-
duced a good inhibitory effect. This suggests that the hydrogen
bond donating groups of thiazolidine-2,4-dione are essential to
orient the molecule more favorably toward the binding site in
the enzyme. Further structure–activity analysis indicated that
the replacement of S in thiazolidine-2,4-dione with NH or CH2
decreased the inhibitory potency of CT-8 significantly, as shown
in Table 1. Replacement of the cyclohexylethyl group with the
hetero five-member ring (compounds 2 and 4) increased the
inhibitory potency. However, replacement of the cyclohexylethyl
group with the hetero six-member ring decreased the inhibitory
potency significantly, as indicated for compounds 7, 9, 11, and
16. The most potent inhibitor of this series of compounds was
compound 2 (5-(4-(2-(thiophen-2-yl)ethoxy)benzylidene)thiazol-
PGE2 is a major inflammatory product derived from arachidonic
acid through the cyclooxygenase pathway, which is involved in
pain and inflammatory responses and is a key player in controlling
various physiological functions. Many studies have reported that
PGE2 is an important mediator of dermal wound healing with spe-
cific effects on fibroblast behavior. Of particular interest is the
work by Kolodsick et al.,30 who reported that PGE2 can inhibit
the differentiation of fibroblasts into myofibroblasts via the EP2
receptor pathway through the up-regulation of cAMP.
PGE2 has been also identified as an important mediator of gas-
tric ulcer healing. Hatazawa et al.31 reported that endogenous PGE2
plays a role in the healing of NSAID-induced intestinal ulcers
through the EP4 receptors. They also reported that the healing–
promoting action of PGE2 is associated with an increase in angio-
genesis by upregulating VEGF expression in the fibroblasts of the
gastric ulcer bed or margin by activating the EP4 receptors.8
Numerous in vivo studies have also identified PGE2 as a potent
anabolic agent that stimulates both modeling (i.e., formation drift
on quiescent surface) and remodeling-dependent (i.e., positive ba-
sic multicellular unit bone balance) bone gain when delivered
intermittently by daily subcutaneous injections.32–40 Prostaglan-
dins, including PGE1, PGE2, and PGF2 , have been demonstrated
a
to stimulate both bone resorption and bone formation but tend
to favor bone formation, thereby increasing bone mass and bone
strength.20,21 Endogenous PGE2 increases locally after fracture
and the inhibition of PGE2 production impairs bone healing.41,42
In contrast, the local administration of PGE2 stimulates bone for-
mation and callus development in animal models.22
idine-2,4-dione) with an IC50 of 0.031 lM. Table 1 summarizes
the inhibitory potency of all these compounds.
15-PGDH catalyzes the NAD+ dependent oxidation of the 15(S)-
hydroxyl group of prostaglandins and is considered to be a key en-
zyme in the biological inactivation of prostaglandins. Therefore,
inhibitors of 15-PGDH will be valuable for the therapeutic manage-
ment of diseases requiring elevated PGE2 levels.
Scheme 1 summarizes the general synthetic routes of thiazol-
idine-2,4-dione derivatives. p-Hydroxybenzaldehyde, as a start-
ing material, was reacted with various substituents to afford
the substituted benzaldehyde intermediate in good yield. The
intermediate obtained was then used for a coupling reaction
Many studies have reported that the local administration of
PGE2 accelerates the healing of gastric ulcers and wounds, and
increases bone formation and callus development in animal
models. However, local administration of PGE2 is an unaccept-
able therapeutic option for human diseases due to the limited
knowledge of the potential changes caused by it on the tissue
and cellular level as well as the biological instability of PGE2.
Therefore, inhibitors of 15-PGDH will be valuable for the thera-
peutic management of diseases requiring elevated prostaglandin
levels.

1430
Y. Wu et al. / Bioorg. Med. Chem. 18 (2010) 1428–1433
O
O
O
a
b
H
H
NH
X
O
R1 OH
R1
O
HO
R1
O
NH
O
X
i
1 - 28
O
O
c
N
R2
X
I
R2
R1
O
O
29, 30
Scheme 1. Reagents and conditions: (a) PPh3, DEAD, THF, 25 °C, 18 h (88%); (b) piperidine, AcOH, reflux, 12 h (90%); (c) NaH, THF, 25 °C, 3 h (85%).
Table 1
Inhibitory potency of the various synthetic thiazolidine-2,4-diones
O
N
R2
X
R1
O
O
Compound
R1
R2
X
IC50 (lM)
CT-8
1
2
3
4
5
6
7
8
Cyclohexylethyl
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
NH
CH2
S
0.051
0.274
0.031
0.713
0.060
1.248
0.660
3.719
0.750
1.442
0.636
1.960
0.287
0.429
0.116
0.893
2.585
0.529
0.232
0.252
0.045
0.124
0.052
0.219
0.172
0.620
0.814
0.865
3.789
ND
2-Thiomorpholine-1,1-dioxideethyl
2-(Thiophen-2-yl)ethyl
2-Morpholinoethyl
2-(Thiophen-3-yl)ethyl
2-Isopropoxyethyl
2-(Pyridin-2-yl)ethyl
2-(Cyclohexylamino)ethyl
2-(Tetrahydro-2H-pyran-2-yl)ethyl
2-(Piperidin-1-yl)ethyl
2-(4-Methylthiazol-5-yl)ethyl
3-Thiomorpholine-1,1-dioxidepropyl
Thiophen-2-ylmethyl
Thiophen-3-ylmethyl
2-Cyclopentylethyl
Furan-2-ylmethyl
Pyridin-2-ylmethyl
4-Methoxybenzyl
4-Methylbenzyl
Benzo[d][1,3]dioxol-5-ylmethyl
Cyclopentylmethyl
4-(Chloromethyl)benzyl
(4-Methylcyclohexyl)methyl
2-(Cyclohexyloxy)ethyl
(2,3-Dihydrobenzo[b][1,4]dioxin-2-yl)methyl
(4-Methyloxycarbonylcyclohexyl)methyl
Biphenyl-4-ylmethyl
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Cyclohexylethyl
Cyclohexylethyl
Cyclohexylethyl
Cyclohexylethyl
CH3
CH2CH2OH
S
0.526
The enzyme was assayed fluorometrically as described in Section 3. The IC50 value was determined using NAD+ (250
lM) as coenzyme and PGE2 (21 lM) as substrate.
15-PGDH was expressed as a GST fusion enzyme using pGEX-2T vector as described in Section 3. ND: No detectable activity.
one were obtained from Sigma. The GST gene fusion pGEX-2T
expression vector was purchased from Pharmacia Corp. The cDNA
of human 15-PGDH was cloned from a human placenta cDNA li-
brary, as described previously.43 All chemical reagents were com-
mercially available. The UV spectra were obtained using a UV–vis
spectrophotometer (SHIMADZU). The TLC plates were prepared
3. Experimental procedures
3.1. Materials
PGE2, NAD+, NADH, Glutathione–Sepharose 4B, dithiothreitol
(DTT), sodium dodecylsulfate (SDS), EDTA, and reduced glutathi-

Y. Wu et al. / Bioorg. Med. Chem. 18 (2010) 1428–1433
1431
using Kieselgel 60 PF254. Column chromatography was performed
using silica gel (230–400 mesh, Whatman Inc.). The NMR spectra
were recorded on a JEOL JNM-LA 300 spectrometer (JOEL, Tokyo,
Japan). The chemical shifts are reported in parts per million (d)
and the signals are quoted as s (singlet), d (doublet), t (triplet), q
(quartet), m (multiplet). Various thiazolidinediones were synthe-
sized using published procedures.44
3.4.1. 5-[4-(2-Thiomorpholine-1,1-dioxideethoxy)benzylidene]-
thiazolidine-2,4-dione (1)
Obtained by recrystallization as a yellow solid (1.21 g, 88%
yield); 1H NMR (300 MHz, DMSO-d6) d 8.19 (s, 1H), 7.73 (s, 1H),
7.56 (d, J = 8.7 Hz, 2H), 7.11 (d, J = 8.7 Hz, 2H), 4.17 (t, J = 10.8 Hz,
2H), 3.09 (t, J = 10.2 Hz, 4H), 3.03 (t, J = 10.2 Hz, 4H), 2.95
(t, J = 10.8 Hz, 2H).
3.2. Expression and purification of 15-PGDH
3.4.2. 5-(4-(2-(Thiophen-2-yl)ethoxy)benzylidene)thiazolidine-
2,4-dione (2)
The sequence of 15-PGDH cDNA plasmid containing BamHI and
EcoRI sites of the pGEX-2T expression vector was used to transform
Escherichia coli BL-21 LysS. The cells were grown in 500 mL LB med-
Obtained by recrystallization as a yellow solid (1.59 g, 87.8%
yield); 1H NMR (300 MHz, DMSO-d6) d 8.12 (s, 1H), 7.73 (s,
1H), 7.56 (d, J = 8.7 Hz, 2H), 7.35 (d, J = 6.0 Hz, 1H), 7.12 (d,
J = 8.7 Hz, 2H), 6.94–6.97 (m, 2H), 4.28 (t, J = 12.6 Hz, 2H),
3.285 (t, J = 12.6 Hz, 2H).
ium containing 50
lg/mL ampicillin at 37 °C and 220 rpm until the
OD600 reached 0.6. Isopropyl b-
D
-thiogalactoside (1 mM) was added
and the cells were allowed to grow for 12 h at 25 °C. The cells were
then harvested by centrifugation at 4000g for 30 min at 4 °C. The cell
pellets was resuspended in 20 mL of a cold cell lysis buffer [1ꢀ PBS
buffer (pH 7.4) containing 1 mM EDTA and 0.1 mM DTT] and soni-
cated (14 ꢀ 10 s at 4 °C). The disrupted cells were centrifuged at
4000g for 20 min at 4 °C. The supernatant was applied slowly to a
Glutathione–Sepharose 4B column (approximately 3 mL), which
was equilibrated at 4 °C with a lysis buffer [1ꢀ PBS buffer (pH 7.4)
containing 1 mM EDTA and 0.1 mM DTT]. The lysis buffer was
washed until the OD280 reached <0.005. The 15-PGDH was eluted
from the Glutathione–Sepharose 4B column by incubation at room
temperature for 5 min with the elution buffer [50 mM Tris–HCl
(pH 8.0) containing 10 mM reduced glutathione, 1 mM EDTA and
0.1 mM DTT]. The concentration of the purified enzyme was deter-
mined and the purity of the 15-PGDH was assessed by SDS–PAGE.
3.4.3. 5-(4-(2-Morpholinoethoxy)benzylidene)thiazolidine-2,4-
dione (3)
Obtained by recrystallization as a yellow solid (1.16 g, 81.7%
yield); 1H NMR (300 MHz, DMSO-d6) d 8.14 (s, 1H), 7.71 (s,
1H), 7.54 (d, J = 8.7 Hz, 2H), 7.10 (d, J = 8.7 Hz, 2H), 4.22 (t,
J = 11.4 Hz, 2H), 3.81 (t, J = 9.6 Hz, 4H), 3.13 (t, J = 11.4 Hz, 2H),
2.76 (t, J = 9.6 Hz, 4H).
3.4.4. 5-(4-(2-(Thiophen-3-yl)ethoxy)benzylidene)thiazolidine-
2,4-dione (4)
Obtained by recrystallization as a yellow solid (1.24 g, 86%
yield); 1H NMR (300 MHz, DMSO-d6) d 8.12 (s, 1H), 7.69 (s, 1H),
7.56 (d, J = 11.7 Hz, 2H), 7.45 (d, J = 7.8 Hz, 1H), 7.31 (d, J = 7.8 Hz,
1H), 7.11 (d, J = 11.7 Hz, 2H), 7.09 (s, 1H), 4.28 (t, J = 13.8 Hz, 2H),
3.07 (t, J = 13.8 Hz, 2H).
3.3. 15-PGDH assay
Assays for the activity of the 15-PGDH inhibitors were per-
formed using a fluorescence spectrophotometer by measuring
the formation of NADH at 468 nm following excitation at
340 nm. 50 mM Tris–HCl (pH 7.5), 0.1 mM DTT, 0.25 mM NAD+,
3.4.5. 5-(4-(2-Isopropoxyethoxy)benzylidene)thiazolidine-2,4-
dione (5)
Obtained by recrystallization as a yellow solid (1.26 g, 85.7%
yield); 1H NMR (300 MHz, CDCl3) d 8.04 (s, 1H), 7.81 (s, 1H), 7.43
(d, J = 9.0 Hz, 2H), 7.02 (d, J = 9.0 Hz, 2H), 4.19 (t, J = 9.6 Hz, 2H),
3.84 (t, J = 9.6 Hz, 2H), 3.65–3.76 (m, 1H), 1.24 (d, J = 6.0 Hz, 6H).
10 lg of the purified enzyme, 21 lM PGE2, and various concentra-
tions of inhibitors (total 2 mL) were added to the cell. Each concen-
tration was assayed in triplicate. The absorbance of the reaction
mixture was read at 340 nm and the activity of the 15-PGDH inhib-
itors was determined from a standard curve prepared from the
absorbance of various concentrations of NADH at 340 nm.
3.4.6. 5-(4-(2-(Pyridin-2-yl)ethoxy)benzylidene)thiazolidine-
2,4-dione (6)
Obtained by recrystallization as a yellow solid (1.21 g, 84.6%
yield); 1H NMR (300 MHz, DMSO-d6) d 10.36 (s, 1H), 8.45 (d,
J = 4.8 Hz, 1H), 7.78 (s, 1H), 7.719–7.28 (m, 1H), 7.49 (d, J = 8.4 Hz,
2H), 7.28 (d, J = 7.8 Hz, 1H), 7.19–7.23 (m, 1H), 6.92 (d, J = 8.4 Hz,
2H), 4.17 (t, J = 14.7 Hz, 2H), 3.05 (t, J = 14.7 Hz, 2H).
3.4. General procedure for the synthesis of compounds 1–28
Diethyl azodicarboxylate (40% in toluene, 2.7 g, 6.2 mmol) was
added slowly to a stirring solution of 4-(2-hydroxyethyl)thiomorph-
oline 1,1-dioxide (1 g, 5.6 mmol), p-hydroxybenzaldehyde (684 mg,
5.6 mmol) and triphenylphosphine (1.62 g, 6.2 mmol) in THF
(20 mL) for 10 min. at 0 °C. The mixture was then stirred at room
temperature until the starting materials (TLC analysis) began to dis-
appear. The resulting solution was concentrated under reduced
pressure and purified by column chromatography over silica gel
(elution with hexane/ethyl acetate, 2:1) to afford 1.37 g of the inter-
mediate, 4-(2-thiomorpholine 1,1-dioxideethoxy)benzaldehyde
(87%), as a yellow oil. A mixture of 4-(2-thiomorpholine 1,1-dioxide-
ethoxy)benzaldehyde (1 g, 3.5 mmol), 2,4-thiazolidinedione (410 mg,
3.5 mmol), piperidine (0.17 mL, 1.75 mmol) and acetic acid
(0.10 mL, 1.75 mmol) in toluene (20 mL) was then placed into a
round bottom flask fitted with a Dean–Stark water trap and stirred
overnight under reflux. After cooling to room temperature, the pre-
cipitate was washed with hexane and dried to afford compound 1.
3.4.7. 5-(4-(2-(Cyclohexylamino)ethoxy)benzylidene) thiazoli-
dine-2,4-dione (7)
Obtained by recrystallization as a yellow solid (1.11 g, 75.5%
yield); 1H NMR (300 MHz, DMSO-d6) d 7.50 (d, J = 8.7 Hz, 2H),
7.31 (s, 1H), 7.07 (d, J = 8.7 Hz, 2H), 4.24 (t, J = 9.9 Hz, 2H), 3.30
(t, J = 9.9 Hz, 2H), 2.88–2.94 (m, 1H), 2.28 (s, 1H), 1.894–2.07 (m,
2H), 1.733–1.89 (m, 2H), 1.57–1.61 (m, 1H), 1.09–1.30 (m, 4H).
3.4.8. 5-(4-(2-(Tetrahydro-2H-pyran-2-yl)ethoxy)benzylidene)-
thiazolidine-2,4-dione (8)
Obtained by recrystallization as a yellow solid (1.27 g, 88.2%
yield); 1H NMR (300 MHz, DMSO-d6) d 8.29 (s, 1H), 7.73 (s, 1H),
7.55 (d, J = 9.0 Hz, 2H), 7.10 (d, J = 9.0 Hz, 2H), 3.98 (d, J = 5.1 Hz,
2H), 3.85–3.89 (m, 2H), 3.60–3.64 (m, 1H), 1.97–2.12 (m, 4H),
1.60–1.86 (m, 2H), 1.28–1.47 (m, 2H).

1432
Y. Wu et al. / Bioorg. Med. Chem. 18 (2010) 1428–1433
3.4.9. 5-(4-(2-(Piperidin-1-yl)ethoxy)benzylidene)thiazolidine-
2,4-dione (9)
3.4.18. 5-(4-(4-Methylbenzyloxy)benzylidene)thiazolidine-2,4-
dione (18)
Obtained by recrystallization as a yellow solid (1.13 g, 79.6%
yield); 1H NMR (300 MHz, DMSO-d6) d 7.52 (s, 1H), 7.41 (d,
J = 10.2 Hz, 2H), 6.97 (d, J = 10.2 Hz, 2H), 4.10 (t, J = 11.1 Hz, 2H),
2.81 (t, J = 11.1 Hz, 2H), 2.38 (m, 4H), 1.41–1.51 (m, 4H), 1.29–
1.31 (m, 2H).
Obtained by recrystallization as a yellow solid (1.15 g, 80.4%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.51 (s, 1H), 7.80 (s, 1H),
7.56 (d, J = 8.7 Hz, 2H), 7.35 (d, J = 7.8 Hz, 2H), 7.21 (d, J = 7.8 Hz,
2H), 7.17 (d, J = 8.7 Hz, 2H), 5.13 (s, 2H), 2.30 (s, 3H).
3.4.19. 5-(4-(Benzo[d][1,3]dioxol-5-ylmethoxy) benzylidene)-
thiazolidine-2,4-dione (19)
Obtained by recrystallization as a yellow solid (1.22 g, 88.4%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.50 (s, 1H), 7.72 (s, 1H),
7.56 (d, J = 9.0 Hz, 2H), 7.16 (d, J = 9.0 Hz, 2H), 7.01 (s, 1H), 6.96
(d, J = 8.1 Hz, 2H), 6.92 (d, J = 8.1 Hz, 1H), 6.01 (s, 2H), 5.06 (s, 2H).
3.4.10. 5-(4-(2-(4-Methylthiazol-5-yl)ethoxy)benzylidene) thia-
zolidine-2,4-dione (10)
Obtained by recrystallization as a yellow solid (1.27 g, 88%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.49 (s, 1H), 8.82 (s, 1H),
7.72 (s, 1H), 7.56 (d, J = 8.7 Hz, 2H), 7.10 (d, J = 8.7 Hz, 1H), 4.24
(t, J = 12.3 Hz, 2H), 3.25 (t, J = 12.3 Hz, 2H), 2.28 (s, 3H).
3.4.20. 5-(4-(Cyclopentylmethoxy)benzylidene)thiazolidine-
2,4-dione (20)
3.4.11. 5-[4-(3-Thiomorpholine-1,1-dioxidepropoxy) benzylidene]-
thiazolidine-2,4-dione (11)
Obtained by recrystallization as a yellow solid (1.16 g, 78.0%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.50 (s, 1H), 7.73 (s, 1H),
7.55 (d, J = 9.0 Hz, 2H), 7.09 (d, J = 9.0 Hz, 2H), 3.92 (d, J = 7.2 Hz,
2H), 2.25–2.35 (m, 1H), 1.75–1.77 (m, 2H), 1.53–1.60 (m, 4H),
1.28–1.34 (m, 2H).
Obtained by recrystallization as
a yellow solid (1.07 g,
81.1%yield); 1H NMR (300 MHz, DMSO-d6) d 8.19 (s, 1H), 7.71 (s,
1H), 7.54 (d, J = 8.1 Hz, 2H), 7.09 (d, J = 8.1 Hz, 2H), 4.09 (t,
J = 12 Hz, 2H), 3.06–3.89 (m, 8H), 2.62 (t, J = 14.1 Hz, 2H), 1.82–
1.91 (m, 2H).
3.4.21. 5-(4-(4-(Chloromethyl)benzyloxy)benzylidene) thiazoli-
dine-2,4-dione (21)
Obtained by recrystallization as a yellow solid (1.12 g, 81.2%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.55 (s, 1H), 7.75 (s, 1H),
7.58 (d, J = 12.3 Hz, 2H), 7.45 (m, 4H), 7.19 (d, J = 12.3 Hz, 2H),
5.22 (s, 2H), 4.76 (s, 2H).
3.4.12. 5-(4-(Thiophen-2-ylmethoxy)benzylidene)thiazolidine-
2,4-dione (12)
Obtained by recrystallization as a yellow solid (1.17 g, 80.7%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.51 (s, 1H), 7.75 (s, 1H),
7.57 (d, J = 8.4 Hz, 2H), 7.56 (t, J = 2.4 Hz, 1H), 7.25 (t, J = 3.3 Hz,
1H), 7.20 (d, J = 8.4 Hz, 2H), 7.05 (m, 1H), 5.37 (s, 2H).
3.4.22. 5-(4-((4-Methylcyclohexyl)methoxy)benzylidene) thiazo-
lidine-2,4-dione (22)
3.4.13. 5-(4-(Thiophen-3-ylmethoxy)benzylidene)thiazolidine-
2,4-dione (13)
Obtained by recrystallization as a yellow solid (1.24 g, 85.5%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.50 (s, 1H), 8.59 (s, 1H),
7.86 (d, J = 7.8 Hz, 1H), 7.73 (s, 1H), 7.57 (d, J = 8.7 Hz, 2H), 7.52
(d, J = 7.8 Hz, 1H), 7.20 (d, J = 8.7 Hz, 2H), 5.25 (s, 2H).
Obtained by recrystallization as a yellow solid (1.17 g, 85.6%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.49 (s, 1H), 7.69 (s, 1H),
7.54 (d, J = 9.0 Hz, 2H), 7.10 (d, J = 9.0 Hz, 2H), 3.96 (d, J = 6.9 Hz,
1H), 3.85 (d, J = 6.6 Hz, 1H), 1.66–1.98 (m, 4H), 1.19–1.52 (m,
4H), 0.98–1.16 (m, 2H), 0.85–0.94 (m, 3H).
3.4.14. 5-(4-(2-Cyclopentylethoxy)benzylidene)thiazolidine-
2,4-dione (14)
3.4.23. 5-(4-(2-(Cyclohexyloxy)ethoxy)benzylidene) thiazolidine-
2,4-dione (23)
Obtained by recrystallization as a yellow solid (1.16 g, 81%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.50 (s, 1H), 7.74 (s, 1H),
7.55 (d, J = 8.7 Hz, 2H), 7.09 (d, J = 8.7 Hz, 2H), 4.14 (t, J = 13.2 Hz,
2H), 1.81–1.98 (m, 1H), 1.700–1.77 (m, 4H), 1.46–1.61 (m, 4H),
1.10-1.19 (m, 2H).
Obtained by recrystallization as a yellow solid (1.14 g, 82.0%
yield); 1H NMR (300 MHz, DMSO-d6) d 8.65 (s, 1H), 7.73 (s, 1H),
7.44 (d, J = 14.7 Hz, 2H), 7.02 (d, J = 14.7 Hz, 2H), 4.20 (t,
J = 9.9 Hz, 2H), 3.30 (t, J = 9.9 Hz, 2H), 3.32–3.40 (m, 1H), 1.96–
2.18 (m, 2H), 1.75–1.77 (m, 2H), 1.55–1.59 (m, 1H), 1.22–1.39
(m, 5H).
3.4.15. 5-(4-(Furan-2-ylmethoxy)benzylidene)thiazolidine-2,4-
dione (15)
Obtained by recrystallization as a yellow solid (1.26 g, 84.6%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.52 (s, 1H), 7.75 (s, 1H),
7.71 (t, J = 1.8 Hz, 1H), 7.57 (d, J = 8.4 Hz, 1H), 7.20 (d, J = 8.4 Hz,
2H), 6.63 (d, J = 3.0 Hz, 1H), 6.48 (d, J = 1.8 Hz, 1H), 5.14 (s, 2H).
3.4.24. 5-(4-((2,3-Dihydrobenzo[b][1,4]dioxin-2-yl)methoxy)ben-
zylidene)thiazolidine-2,4-dione (24)
Obtained by recrystallization as a yellow solid (1.12 g, 82.4%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.51 (s, 1H), 7.73 (s, 1H),
7.58 (d, J = 8.7 Hz, 2H), 7.17 (d, J = 8.7 Hz, 2H), 6.82–6.92 (m, 4H),
4.46–4.58 (m, 1H), 4.41–4.46 (m, 1H), 4.26–4.41 (m, 2H), 4.11–
4.17 (m, 1H).
3.4.16. 5-(4-(Pyridin-2-ylmethoxy)benzylidene)thiazolidine-
2,4-dione (16)
Obtained by recrystallization as a yellow solid (1.24 g, 84.9%
3.4.25. Methyl 4-((4-((2,4-dioxothiazolidine-5-ylidene)methyl)-
phenoxy)methyl)cyclohexanecarboxylate (25)
yield); 1H NMR (300 MHz, DMSO-d6)
d 12.53 (s, 1H), 8.59
(d, J = 4.2 Hz, 1H), 7.87 (t, J = 16.8 Hz, 1H), 7.74 (s, 1H), 7.58 (d,
J = 9.0 Hz, 2H), 7.53 (d, J = 7.8 Hz, 1H), 7.37 (m, 1H), 7.20
(d, J = 9.0 Hz, 2H), 5.25 (s, 2H).
Obtained by recrystallization as a yellow solid (1.03 g, 74.1%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.48 (s, 1H), 7.74 (s, 1H),
7.55 (d, J = 15.9 Hz, 4H), 7.58 (t, J = 9.0 Hz, 2H), 7.10 (d, J = 9.0 Hz,
2H), 3.90 (d, J = 6.6 Hz, 2H), 3.61 (s, 3H), 2.60–2.62 (m, 1H), 1.89–
1.98 (m, 3H), 1.45–1.68 (m, 4H), 1.27–1.34 (m, 2H).
3.4.17. 5-(4-(4-Methoxybenzyloxy)benzylidene)thiazolidine-
2,4-dione (17)
Obtained by recrystallization as a yellow solid (1.19 g, 85.9%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.52 (s, 1H), 7.90 (s, 1H)
7.47 (d, J = 8.7 Hz, 2H), 7.25 (d, J = 8.7 Hz, 2H), 7.31 (d, J = 8.4 Hz,
2H), 7.17 (d, J = 8.4 Hz, 2H), 5.06 (s, 2H), 3,79 (s, 3H).
3.4.26. 5-(4-(Biphenyl-4-ylmethoxy)benzylidene)thiazolidine-
2,4-dione (26)
Obtained by recrystallization as a yellow solid (1.12 g, 83.6%
yield); 1H NMR (300 MHz, DMSO-d6) d 12.51 (s, 1H), 7.74 (s, 1H),

Y. Wu et al. / Bioorg. Med. Chem. 18 (2010) 1428–1433
1433
7.70 (t, J = 15.9 Hz, 4H), 7.58 (t, J = 15.9 Hz, 4H), 7.49 (t, J = 14.7 Hz,
References and notes
2H), 7.38 (m, 1H), 7.21 (d, J = 8.7 Hz, 2H), 5.24 (s, 2H).
1. Anggard, E.; Samuelsson, B. J. Biol. Chem. 1964, 239, 4097.
2. Anggard, E. Acta Physiol. Scand. 1966, 66, 509.
3. Ensor, C. M.; Tai, H. H. J. Lipid Mediators Cell Signalling 1995, 12, 313.
4. Wermuth, B. J. Biol. Chem. 1981, 256, 1206.
5. Johnstone, M. A. Am. J. Ophthalmol. 1997, 124, 544.
6. Roenigk, H. H. Clin. Dermatol. 1988, 6, 119.
7. Jean, F. M.; Laurent, C.; Brigitte, G.; Olivier, G.; Florence, B.; Rui, P.; Christophe,
B.; Maria, D. C.; Roger, R.; Neuwels, M.; Bruno, A. B. Exp. Dermatol. 2008, 17,
821.
3.4.27. 5-(4-(2-Cyclohexylethoxy)benzylidene)imidazolidine-
2,4-dione (27)
Obtained by recrystallization as a yellow solid (1.19 g, 83.0%
yield); 1H NMR (300 MHz, DMSO-d6) d 11.21 (s, 1H), 10.37 (s,
1H), 7.52 (d, J = 7.8 Hz, 2H), 6.88 (d, J = 7.8 Hz, 2H), 6.32 (s, 1H),
3.94 (t, J = 12.6 Hz, 2H), 1.66 (t, J = 12.6 Hz, 2H), 1.58–1.92 (m,
4H), 1.03–1.27 (m, 5H), 0.79–0.86 (s, 2H).
8. Hatazawa, R.; Tanaka, A.; Tanigami, M.; Amagase, K.; Kato, S.; Ashida, Y.;
Takeuchi, K. Am. J. Physiol. Gastrointest. Liver Physiol. 2007, 293, 788.
9. Wallace, J. L. Physiol. Rev. 2008, 88, 1547.
10. Gudis, K.; Sakamoto, C. Dig. Dis. Sci. 2005, 50, S16.
11. Miura, S.; Tatsuguchi, A.; Wada, K.; Takeyama, H.; Shinji, Y.; Hiratsuka, T.;
Futagami, S.; Miyake, K.; Gudis, K.; Mizokami, Y.; Matsuoka, T.; Sakamoto, C.
Am. J. Physiol. Gastrointest. Liver Physiol. 2004, 287, G444.
12. Araki, H.; Komoike, Y.; Matsumoto, M.; Tanaka, A.; Takeuchi, K. Digestion 2002,
66, 145.
13. Halter, F.; Tarnawski, A. S.; Schmassmann, A.; Peskar, B. M. Gut 2001, 49, 443.
14. Mizuno, H.; Akamatsu, T.; Kasuga, M. Gastroenterology 1997, 112, 387.
15. Shigeta, J.; Takahashi, S.; Okabe, S. J. Pharmacol. Exp. Ther. 1998, 286, 1383.
16. Ukawa, H.; Yamakuni, H.; Kato, S.; Taleuchi, K. Dig. Dis. Sci. 1998, 43, 2003.
17. Li, M.; Thompson, D. D.; Paralkar, V. M. Int. Orthop. (SICOT) 2007, 31, 767.
18. Xie, C.; Liang, B.; Xue, M.; Lin, A. S. P.; Loiselle, A.; Schwarz, E. M.; Guldberg, R.
E.; O’Keefe, R. J.; Zhang, X. Am. J. Pathol. 2009, 175, 772.
19. Hartke, J. R.; Lundy, M. W. J. Musculoskelet. Neuronal Interact. 2001, 2, 25.
20. Kawaguchi, H.; Pilbeam, C. C.; Harrison, J. R.; Raisz, L. G. Clin. Orthop. Relat. Res.
1995, 313, 36.
21. Keller, J.; Klamer, A.; Bak, B.; He, S. Z.; Tidd, L.; Schwartz, A.; Sørensen, S.;
Bünger, C. Eur. J. Exp. Musculoskelet. Res. 1992, 1, 86.
22. Parekh, A.; Sandulache, V. C.; Singh, T.; Cetin, S.; Sacks, M. S.; Dohar, J. E.;
Hebda, P. A. Wound Repair Regen. 2009, 17, 88.
23. Futagami, A.; Ishizaki, M.; Fukuda, Y.; Kawana, S.; Yamanaka, N. Lab. Invest.
2002, 82, 1503.
24. Wilgus, T. A.; Bergdall, V. K.; Tober, K. L.; Hill, K. J.; Mitra, S.; Flavahan, N. A.;
Oberyszyn, T. M. Am. J. Pathol. 2004, 165, 753.
3.4.28. 3-(4-(2-Cyclohexylethoxy)benzylidene)pyrrolidine-2,5-
dione (28)
Obtained by recrystallization as a yellow solid (1.2 g, 84% yield);
1H NMR (300 MHz, DMSO-d6) d 8.31 (s, 1H), 7.30 (s, 1H), 7.06 (d,
J = 11.7 Hz, 2H), 6.84 (d, J = 11.7 Hz, 2H), 3.99 (t, J = 13.2 Hz, 2H),
3.85 (s, 2H), 1.63 (t, J = 13.2 Hz, 2H), 1.52–1.77 (m, 6H), 1.43–
1.51 (m, 1H), 1.13–1.27 (m, 2H), 0.90–1.01 (m, 2H).
3.5. General procedure for the synthesis of compounds 29–30
Sodium hydride (21.24 mg, 0.885 mmol, 60% dispersion in oil)
was added to a solution of TD-8 (160 mg, 0.48 mmol) in THF
(20 mL) at 0 °C over a 10 min period with constant stirring under
nitrogen. The mixture was stirred for an additional 10 min. A solu-
tion of iodomethane (205.54 mg, 1.45 mmol) in THF (5 mL) was
added slowly to the reaction mixture and stirred at room temper-
ature for 3 h. The reaction mixture was then extracted with ethyl
acetate and washed with water. The organic layer was dried over
anhyd magnesium sulfate and evaporated. The residual oil was
purified by chromatography over silica gel (elution with hexane/
ethyl acetate, 10:1) to afford compound 29 (142 mg, 85%) as a
white solid.
25. Kohyama, T.; Ertl, R. F.; Valenti, V.; Spurzem, J.; Kawamoto, M.; Nakamura, Y.;
Veys, T.; Allegra, L.; Romberger, D.; Rennard, S. I. Am. J. Physiol. Lung C 2001,
281, L1257.
26. Choung, J.; Taylor, L.; Thomas, K.; Zhou, X.; Kagan, H.; Yang, X.; Polgar, P. J. Cell.
Biochem. 1998, 71, 254.
27. Watanabe, T.; Satoh, H.; Togoh, M.; Taniguchi, S.; Hashimoto, Y.; Kurokawa, K.
J. Cell. Physiol. 1996, 169, 401.
28. Cho, H.; Tai, H. H. Prostaglandins Leukot. Essent. Fatty Acids 2002, 67, 461.
29. Cho, H.; Tai, H. H. Arch. Biochem. Biophys. 2002, 405, 247.
30. Kolodsick, J. E.; Peters-Golden, M.; Larios, J.; Toews, G. B.; Thannickal, V. J.;
Moore, B. B. Am. J. Respir. Cell Mol. Biol. 2003, 29, 537.
31. Hatazawa, R.; Ohno, R.; Tanigami, M.; Tanaka, A.; Takeuchi, K. J. Pharmacol. Exp.
Ther. 2006, 318, 691.
32. Ueno, K.; Haba, T.; Woodbury, D.; Price, P.; Anderson, R.; Jee, W. S. S. Bone 1985,
6, 79.
3.5.1. 5-(4-(2-Cyclohexylethoxy)benzylidene)-3-methylthiazoli
dine-2,4-dione (29)
1H NMR (300 MHz, CDCl3) d 7.87 (s, 1H), 7.48 (d, J = 8.7 Hz, 2H),
6.99 (d, J = 8.7 Hz, 2H), 4.08 (t, J = 13.2 Hz, 2H), 3.24 (s, 3H), 1.67–
1.78 (m, 4H), 1.45–1.54 (m, 1H), 1.11–1.26 (m, 4H), 0.83–1.05
(m, 4H).
33. Tang, L. Y.; Jee, W. S. S.; Ke, H. Z.; Kimmel, D. B. J. Bone Miner. Res. 1992, 7, 1093.
34. Ke, H. Z.; Jee, W. S. S.; Zeng, Q. Q.; Li, M.; Ling, B. Y. Bone Miner. 1993, 21, 189.
35. Li, M.; Jee, W. S. S.; Ke, H. Z.; Liang, X. G.; Lin, B. Y.; Ma, Y. F.; Setterberg, R. B.
Bone 1993, 14, 283.
36. Ma, Y. F.; Ke, H. Z.; Jee, W. S. S. Bone 1994, 15, 137.
37. Jee, W. S. S.; Ma, Y. F. Bone 1997, 21, 297.
38. Yao, W.; Jee, W. S. S.; Zhou, H.; Lu, J.; Cui, L.; Setterberg, R.; Liang, T.; Ma, Y. Bone
1999, 25, 697.
39. Zhou, H.; Ma, Y. F.; Yao, W.; Cui, L.; Setterberg, R. B.; Liang, T. C.; Jee, W. S. S.
Calcif. Tissue Int. 2001, 68, 179.
3.5.2. 5-(4-(2-Cyclohexylethoxy)benzylidene)-3-(2-hydroxy ethyl)-
thiazolidine-2,4-dione (30)
Obtained by chromatography over silica gel (elution with hex-
ane/ethyl acetate, 10:1) as a white solid (180 mg, 79% yield); 1H
NMR (300 MHz, CDCl3) d 7.88 (s, 1H), 7.49 (d, J = 14.4 Hz, 2H), 7.01
(d, J = 14.4 Hz, 2H), 4.08 (t, J = 13.2 Hz, 2H), 4.00 (t, J = 10.2 Hz, 2H),
3.89 (t, J = 10.2 Hz, 2H), 2.05 (m, 1H), 1.67–1.78 (m, 7H), 1.47–1.53
(m, 1H), 1.18–1.28 (m, 3H), 0.96–1.03 (m, 2H).
40. Tian, X. Y.; Zhang, Q.; Zhao, R.; Setterberg, R. B.; Zeng, Q. Q.; Iturria, S. J.; Ma, Y.
F.; Jee, W. S. S. Bone 2008, 42, 914.
41. Dekel, S.; Lenthall, G.; Francis, M. J. J. Bone Joint Surg. Br. 1981, 63, 185.
42. Keller, J.; Bünger, C.; Andreassen, T. T.; Bak, B.; Lucht, U. Acta Orthop. Scand.
1987, 58, 379.
43. Ensor, C. M.; Yan, J. Y.; Okita, R. T.; Tai, H. H. J. Biol. Chem. 1980, 285,
14888.
Acknowledgment
This work was supported by National Research Foundation of
Korea (NRF) Grant funded by the Ministry of Education, Science
and Technology (MEST) through the Research Center for Resistant
Cells (R13-2003-009).
44. Sehda, T.; Mizuno, K.; Tawada, H.; Sugiyama, Y.; Fujita, T.; Kawamatsu, Y. Chem.
Pharm. Bull. 1982, 30, 3580.