Discovery of a series of acrylic acids and their derivatives as chemical leads for selective EP3 receptor antagonists

Article abstract of DOI:10.1016/j.bmc.2009.08.007

A series of acrylic acids and their structurally related compounds were evaluated for their binding affinity to four EP receptor subtypes (EP1-4). Starting from the initial hit 3, which was discovered in our in-house library, compounds 4 and 5 were identified as new chemical leads as candidates for further optimization towards a selective EP3 receptor antagonist. The identification process of these compounds and their pharmacokinetic profiles are presented.

Full text of DOI:10.1016/j.bmc.2009.08.007

Bioorganic & Medicinal Chemistry 17 (2009) 6567–6582
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Discovery of a series of acrylic acids and their derivatives as chemical leads
for selective EP3 receptor antagonists
*
Masaki Asada , Tetsuo Obitsu, Toshihiko Nagase, Isamu Sugimoto, Yoshiyuki Yamaura, Kazutoyo Sato,
Masami Narita, Shuichi Ohuchida, Hisao Nakai, Masaaki Toda
Minase Research Institute, Ono Pharmaceutical Co., Ltd, Shimamoto, Mishima, Osaka 618-8585, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of acrylic acids and their structurally related compounds were evaluated for their binding affinity
to four EP receptor subtypes (EP1-4). Starting from the initial hit 3, which was discovered in our in-house
library, compounds 4 and 5 were identified as new chemical leads as candidates for further optimization
towards a selective EP3 receptor antagonist. The identification process of these compounds and their
pharmacokinetic profiles are presented.
Received 3 July 2009
Revised 31 July 2009
Accepted 1 August 2009
Available online 8 August 2009
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Prostaglandin
EP3 receptor
Antagonist
Pyrazole
1. Introduction
antagonist is expected to be a new therapeutic agent to treat pyr-
exia, pain, threatened abortion and peripheral occupied arterial
Prostanoids, which include prostaglandins (PGs) and thrombox-
anes (TXs), are the oxidative metabolites of arachidonic acid by
cyclooxygenase. They play important roles in a multitude of signifi-
cant physiological processes. During the last several decades, a large
number of structural analogs of PGs were designed, synthesized and
evaluated as potential drugs. Some of these drug candidates have
been launched as clinically useful drugs although they still show
non-selective receptor affinity during recent reassessments.
disease (PAOD).
During our research, two EP3 selective antagonists 1 and 2
(Fig. 1) were reported by Merck8 and de CODE,9 respectively. Of
these, compound 2 (DG-041) has been clinically evaluated for the
treatment of PAOD by the de CODE. Herein we report on our dis-
covery process of new chemical leads 4 and 5 as selective EP3
receptor antagonists starting from a newly identified hit 3 from
our in-house library as shown in Scheme 1.
Coleman et al. proposed the existence of receptors specific for
PGF, PGE, PGD, PGI and TX that were named FP, EP, DP, IP and TP
receptors, respectively.1 They further classified the EP receptor into
four subtypes (EP1, EP2, EP3 and EP4), all of which respond to PGE2
in different ways. It is well known that PGE2 is the most widely
produced prostaglandin in the body and exhibits versatile physio-
logical responses through its interaction with four receptor sub-
types. Characterization of these receptors at the molecular level
has resulted in renewed interest in this field. The EP3 receptor
has been detected in many organs including the brain, kidney,
uterus and gastrointestinal tract. Recent studies utilizing KO mice,
in which the EP3 receptor subtype is specifically knocked out, sug-
gest that the EP3 receptor plays key roles in regulating hyperalge-
sia,2 pyrexia,3 uterine contraction,4 gastric acid secretion,5 platelet
aggregation6 and thrombosis.7 Thus, a selective EP3 receptor
2. Chemistry
Synthesis of test compounds listed in Tables 1–4 is outlined in
Schemes 2–8.
O
O
O
O
S
O
O
O
N
S
F
S
H
N
Cl
H
N
Br
Cl
Cl
Cl
1
2
* Corresponding author. Tel.: +81 75 961 1151; fax: +81 75 962 9314.
E-mail address: m.asada@ono.co.jp (M. Asada).
Figure 1. Reported EP3 receptor antagonists.
0968-0896/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2009.08.007

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M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
COOH
O
X
COOH
*
*
4 X =
5 X =
OH
*
*
O
O
N
N
HCl
N
N
3
(An initial hit)
(New chemical leads)
Scheme 1. Discovery of new chemical leads as selective EP3 antagonists.
a)
COOH
O
COOMe
COOMe
OH
b,c
a
OMOM
O
O
OH
O
22
24
6
O
OTs
MOMO
23
b)
CHO
O
COOH
O
CHO
OH
OMOM
OH
a
d,c
R
R
O
R
O
25 R = Me
27 R = Me
28 R = OMe
7 R = Me
26 R = OMe
8 R = OMe
Scheme 2. Synthesis of 6–8. Reagents: (a) 23, NaH, DMF; (b) NaOHaq, THF, MeOH; (c) HCl–dioxane; (d) malonic acid, piperidine, pyridine.
R
b, c
a
HO
HO
AcO
OH
OMOM
OMOM
31 R = CHO
32 R =
29
30
d
COOEt
*
COOEt
COOEt
OMOM
e
h
O
Y
N
X
N
33 X =
34 X =
35 Y = H
36 Y =
OH
N
*
*
i
f, g
N
O
j
*
k
O
*
37 Y =
38 Y =
l
O
*
*
39 Y =
COOH
9
Y =
m, n
O
O
Y
*
*
N
O
HCl
10 Y =
11 Y =
N
O
*
*
12 Y =
Scheme 3. Synthesis of 9–12. Reagents: (a) MOMCl, NaH, DMF; (b) n-BuLi, t-BuLi, TMEDA, Et2O then N-formylpiperidine; (c) Ac2O, pyridine; (d) ethyl diethylphospho-
noacetate, NaH, THF; (e) NaOEt, EtOH; (f) MsCl, Et3N, THF; (g) imidazole, toluene; (h) HCl–dioxane, EtOH; (i) 3-phenoxypropyl bromide, NaH, DMF; (j) 4-phenoxybutyl
bromide, NaH, DMF; (k) 2-(benzofuran-2-yl)ethanol, DEAD, Ph3P, THF; (l) 2-(naphthalen-2-yl)ethanol, DEAD, Ph3P, THF; (m) NaOHaq, THF, MeOH; (n) HCl–dioxane.

M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
6569
a)
b)
COOEt
X
OMOM
33 X =
40 X =
OH
*
*
a, b
N
N
a, c
a, d
O
41 X =
42 X =
N
*
*
O
COOH
OH
COOMe
OMOM
COOMe
OH
j
g
OH
e, f
X
OMOM
H2N
X
I
45 X = I
43
44
*
*
h
48 X =
*
*
46 X =
47 X =
i
S
COOEt
k, l
49 X =
S
X
OMOM
*
*
50 X =
51 X =
S
c)
COOEt
COOH
COOEt
OMOM
o
m, n
X
O
X
O
X
N
N
N
N
N
N
*
*
40 X =
41 X =
42 X =
*
*
52 X =
53 X =
54 X =
*
*
4
X =
O
O
O
N
N
N
O
13 X =
16 X =
O
*
*
O
*
*
*
*
50 X =
51 X =
55 X =
56 X =
14 X =
15 X =
S
S
S
*
*
*
Scheme 4. Synthesis of 4 and 13–16. Reagents: (a) MsCl, Et3N, THF; (b) pyrazole, NaH, DMF; (c) 2-pyrrolidone, NaH, DMF; (d) phenol, NaH, DMF; (e) NaNO2aq, H2SO4aq then
KIaq; (f) concd H2SO4, MeOH; (g) MOMCl, NaH, DMF; (h) benzylzinc bromide, Pd2(dba)3, DPPF, THF; (i) 2-thienylmethylzinc bromide, Pd2(dba)3, DPPF, THF; (j) LiAlH4, THF; (k)
SO3–pyridine, DMSO, Et3N, CH2Cl2; (l) ethyl diethylphosphonoacetate, NaH, THF; (m) HCl–dioxane, EtOH; (n) 2-(naphthalen-2-yl)ethanol, ADDP, Ph3P, THF; (o) NaOHaq, THF,
MeOH.
COOH
COOEt
b
a
O
O
52
N
N
N
N
57
5
Scheme 5. Synthesis of 5. Reagents: (a) NaBH4, NiCl2–6H2O, THF, EtOH; (b) NaOHaq, THF, MeOH.
Compounds
6
and 7–8 possessing the 6-hydroxy-2,5,7,8-
of 24 followed by acidic deprotection of the methoxymethyl
tetramethylchromane moiety were synthesized as shown in
Scheme 2a and b, respectively. O-Alkylation of 22 with 2310 in
the presence of sodium hydride afforded 24. Alkaline hydrolysis
(MOM) group provided 6. O-Alkylation of compounds 25 and 26
in the presence of sodium hydride afforded 27 and 28, respectively.
Perkin reaction of the aldehydes 27 and 28 with malonic acid in the

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M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
CHO
COOH
CHO
OH
c
b
O
O
O
O
R
a
O
60
17
58 R = H
*
59 R =
Scheme 6. Synthesis of 17. Reagents: (a) benzyl chloride, NaHCO3, KI, CH3CN; (b) 2-(naphthalen-2-yl)ethanol, ADDP, Ph3P, THF; (c) malonic acid, piperidine, pyridine.
OH
O
COOEt
O
O
NO2
d
b
X
X
OHC
61 R = H
O R
63 X = CHO
65 X =
66 X =
OH
a
*
*
c
e, f
N
62 R =
64 X =
OH
N
*
*
COOH
O
O
g
N
N
19
Scheme 7. Synthesis of 19. Reagents: (a) 2-(naphthalen-2-yl)ethanol, ADDP, Ph3P, THF; (b) benzaldoxime, t-BuOK, DMSO; (c) NaBH4, EtOH, (d) ethyl bromoacetate, NaH,
DMF; (e) PBr3, CH2Cl2; (f) pyrazole, NaH, DMF; (g) NaOHaq, THF, MeOH.
Y
a)
I
R
b
f
X
O
O
MeOOC
a
OH
N
g
N
67 R = NH2
68 R = I
69 X = COOMe
c
72 Y =
OH
*
70 X =
OH
*
*
73 Y = CHO
d, e
N
N
71 X =
COOH
h
O
N
N
18
b)
c)
COOEt
COOH
j
i
O
O
71
71
N
N
N
N
N
N
74
20
A
COOH
O
n
k
O
O
N
N
21
75 A = COOMe
l
76 A =
77 A =
OH
O
*
*
m
COOtBu
Scheme 8. Synthesis of 18 and 20–21. Reagents: (a) NaNO2aq, concd HCl then KIaq; (b) 2-(naphthalen-2-yl)ethanol, ADDP, Ph3P, THF; (c) DIBAL-H, CH2Cl2, (d) MsCl, Et3N,
THF; (e) pyrazole, NaH, DMF; (f) propargyl alcohol, CuI, PdCl2(Ph3P)2, tetrabutylammonium iodide, Et3N, DMF; (g) Dess–Martin periodinate, CH2Cl2; (h) NaClO2, 2-methyl-2-
butene, NaH2PO4, t-BuOH, H2O; (i) 4-ethoxy-4-oxobutylzinc bromide, PdCl2(dppf), THF; (j) NaOHaq, THF, MeOH; (k) CO, Pd(OAc)2, DPPF, Et3N, DMF, MeOH; (l) LiAlH4, THF;
(m) t-butyl bromoacetate, tetrabutylammonium hydrogen sulfate, NaOHaq, toluene; (n) TFA, anisole, CH2Cl2.

M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
6571
presence of piperidine in pyridine followed by deprotection under
acidic conditions resulted in the corresponding acrylic acid deriva-
tives 7 and 8, respectively.
Phenoxyacetic acid analog 19 was prepared from 3-hydroxy-4-
nitrobenzaldehyde (61) as shown in Scheme 7. O-Alkylation of 61
with 2-(naphthalen-2-yl)ethanol under the Mitsunobu reaction
condition afforded 62, the nitro group of which was converted to
a hydroxyl group with benzaldoxime in the presence of potassium
t-butoxide to afford 63.12 Reduction of the aldehyde 63 gave 64,
selective O-alkylation of which with ethyl bromoacetate in the
presence of sodium hydride afforded 65. Bromination of 65 fol-
lowed by the treatment with pyrazole gave 66, alkaline hydrolysis
of which provided 19.
Synthesis of 18 and 20–21 is described in Scheme 8a–c, respec-
tively. Methyl 4-amino-3-hydroxybenzoate (67) was converted to
an iodide 68 by the conventional method as shown in Scheme
8a. O-Alkylation of 68 with 2-(naphthalen-2-yl)ethanol under the
Mitsunobu reaction condition afforded 69, which was reduced
with diisobutylaluminum hydride to afford 70. Methanesulfonyla-
tion of 70 followed by the treatment with pyrazole provided 71.
Sonogashira reaction of 71 with propargyl alcohol afforded 72, oxi-
dation reaction of which provided an aldehyde 73. Further oxida-
tion of 73 afforded the corresponding carboxylic acid 18.
Synthesis of 20 is shown in Scheme 8b. A palladium-catalyzed
cross coupling reaction of 71 and an alkyl zinc reagent afforded
74, alkaline hydrolysis of which provided 20. Compound 21 was
prepared from 71 as shown in Scheme 8c. A palladium-catalyzed
insertion reaction of carbon monoxide into 71 in the presence of
methanol afforded 75, which was reduced with lithium aluminum
hydride to provide 76. O-Alkylation of the hydroxymethyl residue
of 76 with t-butyl bromoacetate under phase transfer conditions13
afforded 77, which was converted to 21 by a deprotection reaction
with trifluoroacetic acid-anisole.
Synthesis of 9–12 is shown in Scheme 3. O-Alkylation of the
phenolic hydroxyl group of 3-hydroxybenzyl alcohol (29) with
chloromethyl methyl ether in the presence of sodium hydride
afforded 30. 4-Formyl-3-(methoxymethoxy)benzylacetate (31)
was prepared from 30 by the following sequential reactions:
(1) lithiation of the benzylic hydroxyl group with n-butyl lith-
ium, (2) ortho-lithiation with t-butyl lithium, (3) formylation
with N-formylpiperidine, and (4) acetylation with acetic anhy-
dride in pyridine. Horner–Emmons olefination of 31 with ethyl
diethylphosophonoacetate in the presence of sodium hydride
provided the unsaturated ester 32. Deprotection of the O-acetate
of 32 with sodium ethoxide in ethanol afforded 33. Methanesulf-
onylation of 33 followed by the reaction with imidazole in
toluene resulted in 34, acidic deprotection of which afforded
35. O-Alkylation of 35 with 3-phenoxypropyl bromide and
4-phenoxybutyl bromide in the presence of sodium hydride
afforded 36 and 37, respectively. Mitsunobu reaction of 35 with
2-(benzofuran-2-yl)ethanol and 2-(naphthalen-2-yl)ethanol pro-
vided 38 and 39, respectively. Alkaline hydrolysis of 36–39
followed by treatment with hydrogen chloride produced 9–12,
respectively.
Synthesis of 4 and 13–16 is outlined in Scheme 4a–c. As
shown in Scheme 4a, ethyl acrylates 40–42 were prepared from
33 by methanesulfonylation followed by substitution reactions
with pyrazole, 2-pyrrolidone and phenol in the presence of so-
dium hydride. As shown in Scheme 4b, ethyl acrylates 50 and
51 were synthesized from 4-amino-2-hydroxy benzoic acid
(43). Treatment of 43 with sodium nitrite followed by the addi-
tion of potassium iodide and then esterification with methanol
afforded 44. Protection of the phenolic hydroxyl group of 44 as
a MOM ether gave a protected iodide 45. A palladium-catalyzed
coupling reaction of 45 with benzylzinc bromide and 2-thie-
nylmethylzinc bromide afforded 46 and 47, respectively. Reduc-
tion of 46 and 47 produced the corresponding benzyl alcohols 48
and 49, respectively. The oxidation reaction of 48 and 49 with
sulfur trioxide-pyridine in dimethyl sulfoxide-triethylamine fol-
lowed by Horner–Emmons olefination afforded ethyl acrylates
50 and 51, respectively. As shown in Scheme 4c, acidic deprotec-
tion of the MOM ether of 40–42, 50 and 51 followed by Mitsun-
obu reaction with 2-(naphthalen-2-yl)ethanol afforded 52–56,
alkaline hydrolysis of which afforded 4, 13, 16, 14 and 15,
respectively.
3. Results and discussion
Test compounds listed in Tables 1–4 were biologically evalu-
ated for their inhibition of the specific binding of a radiolabeled li-
gand, [3H]PGE2 to membrane fractions prepared from cells stably
expressing each mouse EP1, EP2, EP3
EP3 receptor antagonist activity was determined by a Ca2+ assay
using mouse EP3 receptor expressed on CHO cells in the presence
a and EP4 receptors. The
a
of 0.1% bovine serum albumin (BSA).
In the course of our screening program of a selective EP3
receptor antagonist, 2-alkoxy-4-(imidazol-1-yl)methylphenylacry-
lic acid 3, which was structurally distinct from previously reported
ones (Fig. 1) and exhibited moderate binding affinity for the EP3
receptor with good subtype selectivity, was identified as an initial
hit compound. As depicted in Figure 2, the initial hit compound 3
was believed to have a structural analogy to PGs regarding the
The phenyl propanoic acid derivative 5 was prepared from 52 as
described in Scheme 5. Reduction of the acrylate 52 with sodium
borohydride in the presence of nickel chloride afforded 57, alkaline
hydrolysis of which produced 5.
Synthesis of 17 is described in Scheme 6. Regioselective O-
benzylation of 2,4-dihydroxybenzaldehyde (58) afforded 59,11
O-Alkylation of 59 with 2-(naphthalen-2-yl)ethanol under the
Mitsunobu reaction condition provided 60. Perkin reaction of 60
with malonic acid in the presence of piperidine in pyridine pro-
duced 17.
acidic part, which corresponds to the
a-chain and the lipophilic
part, which corresponds to the -chain. Furthermore, PGEs are re-
x
garded as a series of compounds possessing 2,3,4-trisubstituted
cyclopentanone as a core template while 3 is regarded as a com-
pound possessing 1,2,4-trisubstituted benzene as a core template.
Based on historical evidence, chemical modification of the
a- and
acidic part
O
COOH
core
template
α chain (acidic part)
COOH
core
OH
O
template
lipophilic part
ω chain (lipophilic part)
N
HO
OH
O
N
PGE
3
2
Figure 2. Structural analogy of PGE2 and 3.

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M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
x
-chains of PGs has been shown to be crucial for receptor affinity
loss of EP3 receptor affinity. Thus, the basic imidazol-1-ylmethyl
moiety was found to be required for 3 to have potent EP3 receptor
affinity and/or subtype selectivity.
Second, optimization of the 2-alkoxy moiety of 3 was carried
out as shown in Table 2. Replacement of the 6-hydroxy-2,5,7,8-
tetramethylchroman-2-ylethyl moiety of 3 with 3-phenoxypropyl
and 4-phenoxybutyl afforded 9 and 10, respectively corresponding
to 4.4-fold less potent and 3.5-fold less potent binding affinities.
Replacement of the 6-hydroxy-2,5,7,8-tetramethylchroman-2-
and/or subtype selectivity. Given this information, optimization of
the acidic and lipophilic part of 3 including another substituent,
the imidazol-1-ylmethyl part, was considered to be a promising
approach for increasing the receptor affinity and subtype
selectivity.
First, our focus was on the optimization of the imidazol-1-yl-
methyl moiety as described in Table 1. Replacement of the imida-
zol-1-ylmethyl moiety of 3 with smaller groups such as hydrogen,
methyl and methoxy groups afforded 6, 7 and 8, respectively with
a gradual decrease in the binding affinity. Compounds 6 and 7 still
retained subtype selectivity while 8 showed EP4 selectivity with a
ylethyl moiety of 3 with the more
p-electron rich benzofuran-2-
ylethyl and naphtalen-2-ylethyl moiety afforded 11 and 12,
respectively with an increase in the receptor affinity. The naphtha-
Table 1
Activity profiles of the initial hit 3 and its derivatives
COOH
OH
X
O
O
Compound
X
Binding Ki (nM)
Antagonist activity IC50 (nM)
EP3
EP1
EP2
EP3
EP4
*
N
3
>10,000
>10,000
63
>10,000
600
N
6
7
8
H
Me
OMe
>10,000
>10,000
>10,000
1200
5700
6800
530
940
>10,000
2600
2200
920
4800
3100
>10,000
Table 2
Effect of the alkoxy moiety on activity profiles
COOH
O
R
N
N
Compound
R
Binding Ki (nM)
Antagonist activity IC50 (nM)
EP3
EP1
EP2
EP3
63
EP4
OH
3
>10,000
>10,000
>10,000
600
O
O
*
9
>10,000
>10,000
>10,000
>10,000
>10,000
>10,000
>10,000
>10,000
280
220
44
>10,000
>10,000
4300
3000
3500
330
50
*
*
O
10
11
12
O
*
*
16
2200

M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
6573
Table 3
Effect of the imidazol-1-ylmethyl side chain on activity profiles
COOH
X
O
Compound
X
Binding Ki (nM)
Antagonist activity IC50 (nM)
EP3
EP1
EP2
EP3
16
EP4
N
*
12
4
>10,000
>10,000
3300
2200
50
N
N
N
2900
6400
12
670
73
*
O
13
5900
110
2300
580
N
*
*
14
15
16
17
>10,000
>10,000
>10,000
>10,000
>10,000
2100
130
150
130
850
2100
400
150
S
2200
*
O
*
*
9200
2600
140
O
1200
>10,000
1500
len-2-ylethyl analogue 12 exhibited 3.9-fold more potency in bind-
ing affinity and 12-fold more potency in antagonist activity relative
to 3 while retaining subtype selectivity. Thus, the lipophilic p-elec-
tron rich moieties such as benzofuran-2-ylethyl and naphthalene-
2-ylethyl moieties were found to be required for the increase in
potency.
ded the phenylpropynoic acid analogue 18 with 8.3-fold less po-
tent binding affinity and 16-fold less potent antagonist activity.
Replacement of the acrylic acid moiety of 4 with an oxyacetic acid
moiety and a methyleneoxyacetic acid moiety afforded 19 and 21,
respectively with decreased activities. The larger decrease in bind-
ing affinity of the oxygen-containing analogues 19 and 21 relative
to the others 4–5, 18 and 20 was considered to be due to the
hydrophilic ether oxygen, which is unfavorable for these analogues
to interact with the receptor.
As shown in Table 3, further optimization of the imidazol-1-yl-
methyl moiety of 12 was continued. Replacement of the imidazol-
1-ylmethyl moiety of 12 with the less basic pyrazol-1-ylmethyl
moiety afforded 4 with retention of the activities and subtype
selectivity. Replacement of the imidazol-1-ylmethyl moiety of 12
with pyrrolidon-1-ylmethyl, benzyl, thiophen-2-ylmethyl and
phenoxymethyl moieties provided 13–16, respectively with nearly
10-fold less potent binding affinity and significantly less potent
antagonist activity. A marked decrease in the activities was ob-
served in the corresponding benzyloxy analogue 17. As described
above, the imidazol-1-ylmethyl analogue 12 and the pyrazol-1-yl-
methyl analogue 4 clearly showed stronger EP3 receptor affinity,
antagonist activity and better subtype selectivity than the other
analogues 13–17.
Further optimization of the acidic chain of 4, which is one of the
most optimized structure, was carried out as shown in Table 4. Sat-
uration of the acrylic acid moiety provided phenylpropanoic acid
analogue 5 with nearly equipotent binding affinity and increased
antagonist activity. The corresponding phenylbutanoic acid ana-
logue 20 showed slightly decreased binding affinity and decreased
antagonist activity. Unexpectedly this remarkable decrease in the
antagonist activity of 20 compared with its potent binding affinity
was estimated to be due to increased protein binding resulting
from its increased lipophilicity. Replacement of the trans-double
bond of the acrylic acid moiety of 4 with a linear triple bond affor-
The newly identified chemical leads 4–5 and 12 were investi-
gated for their profiles to inhibit major cytochrome P450 (CYP) iso-
zymes, 1A2, 2C9, 2C19, 2D6 and 3A4. Data are summarized in Table
5. For compound 12, the IC50 values were below 1
lM for 1A2, 2C9,
2C19, 3A4 and 4.4 M for 2D6. These inhibitory activities for all the
l
isozymes were predicted based on the fact that its partial structure
possesses an imidazol-1-ylmethyl moiety, whereas 4 and 5, in
which the imidazol-1-ylmethyl moiety is replaced with the pyra-
zol-1-ylmethyl moiety, showed significantly weaker inhibitory
activities for these five isozymes.
Compounds 4 and 5 were also investigated for their pharmaco-
kinetic profiles in both in vitro and in vivo tests as shown in Table
6. The remaining percentage (% remaining) of intact 4 and 5 after
in vitro incubation with human liver microsomes (HLM) and rat li-
ver microsomes (RLM) for 15 min at 37 °C were 100% and 72–73%,
respectively. They were found to be metabolically more stable in
HLM relative to RLM based on the above data. The pharmacokinet-
ics of 4 and 5 were evaluated via oral administration to rats at
10 mg/kg as shown in Table 6. While the Cmax value and the AUC
value of 4 was 0.943
the AUC value of 5 was 8.32
of 5 were found to be more than 8 times higher than those of 4.
l
g/mL and 1.36
lg h/mL, the Cmax value and
l
g/mL and 22.9
l
g h/mL. The values

6574
M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
Table 4
Effect of the linker between COOH and the core benzene ring on activity profiles
X
COOH
O
N
N
Compound
X
Binding Ki (nM)
Antagonist activity IC50 (nM)
EP3
EP1
EP2
EP3
12
EP4
670
*
*
4
5
2900
3300
73
22
*
7100
2800
12
99
1100
*
*
18
19
>10,000
>10,000
>10,000
>10,000
2900
1200
2600
*
O
*
260
>10,000
*
*
20
21
4000
1800
1300
39
1400
460
540
*
*
>10,000
210
>10,000
O
*
A more detailed pharmacokinetic study (Table 7) indicated that 5
showed low clearance (CLtot 2.77 mL/min/kg) and good oral bio-
availability (F 53%).
tive EP3 receptor antagonist starting from the initial hit
compound 3. By replacing the imidazol-1-ylmethyl moiety of
12 with the pyrazol-1-ylmethyl moiety, 4 and 5 were found to
have a significant reduction in CYP inhibition. Pharmacokinetic
studies demonstrated that 5 showed improved pharmacokinetic
profiles relative to 4. Further optimization of 4 and 5 to improve
their potency and subtype selectivity will be reported in due
course.
4. Conclusion
In conclusion, compounds 4 and 5 possessing a pyrazol-1-yl-
methyl moiety were identified as new chemical leads for a selec-
5. Experimental
5.1. Chemistry
Table 5
CYP inhibitory activities of 12, 4 and 5
Compd
CYP inhibition IC50
2C19
(lM)
1A2
2C9
2D6
3A4
5.1.1. General procedures
Analytical samples were homogeneous as confirmed by TLC,
and afforded spectroscopic results consistent with the assigned
structures. Proton nuclear magnetic resonance spectra (1H NMR)
were taken on a Varian Mercury 300 spectrometer, Varian GEM-
INI-200 or VXR-200s spectrometer using deuterated chloroform
(CDCl3), deuterated dimethylsulfoxide (DMSO-d6) or deuterated
methanol (CD3OD) as the solvent. Fast atom bombardment mass
spectra (FAB-MS, HRMS) and electron ionization (EI) were obtained
on a JEOL JMS-DX303HF spectrometer. Atmospheric pressure
12
4
5
<1
>30
>30
<1
12.8
30.0
<1
30.0
>30
4.4
>30
>30
<1
>30
>30
Table 6
In vitro metabolic stability and pharmacokinetic parameters of oral administration of
4 and 5
Compd
In vitro stability
(% remaining)
Pharmacokinetic parameters in rat
at 10 mg/kg po
chemical ionization (APCI) was determined on
a HITACHI
MI200H spectrometer. Infrared spectra (IR) were measured in a
Perkin–Elmer FT-IR 1760X spectrometer. Melting points and
results of elemental analyses were uncorrected. Column chroma-
tography was carried out on silica gel [Merck Silica Gel 60
(0.063–0.200 mm), Wako gel C-200 or Fuji Silysia FL60D]. Thin
layer chromatography was performed on silica gel (Merck TLC or
HPTLC plates, Silica Gel 60 F254). The following abbreviations
for solvents and reagents are used; tetrahydrofuran (THF),
diethylether (Et2O), dimethylsulfoxide (DMSO), ethyl acetate
(EtOAc), dimethylformamide (DMF), methanol (MeOH), ethanol
(EtOH), t-butylalcohol (t-BuOH), acetic acid (AcOH), triethylamine
(TEA), diethyl azodicarboxylate (DEAD), 1,10-(azodicarbonyl)dipi-
peridine (ADDP) and 1,10-bis(diphenylphosphino)ferrocene (DPPF).
HLM
RLM
Cmax
(
l
g/mL)
AUC0–4h
4
5
100
100
72
73
0.943
8.32
1.36
22.9
Compounds 4 and 5 were administered as the sodium salt.
Table 7
Pharmacokinetic parameters of 5
t1/2 (h)
CLtot (mL/min/kg)
2.77
Vss (mL/kg)
F (%)
2.93
538
53
Compound 5 was administered as the sodium salt at 10 mg/kg iv and 10 mg/kg po.

M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
6575
5.1.2. Methyl (2E)-3-{2-[2-(6-methoxymethoxy-2,5,7,8-
tetramethyl-3,4-dihydro-2H-chromen-2-yl)ethoxy]phenyl}
acrylate (24)
5.1.6. 4-Methoxy-2-{2-[6-(methoxymethoxy)-2,5,7,8-
tetramethyl-3,4-dihydro-2H-chromen-2-
yl]ethoxy}benzaldehyde (28)
To a stirred solution of 22 (160 mg, 0.900 mmol) in DMF (2 mL)
was added NaH (62.7% in oil, 46 mg, 1.20 mmol) at 0 °C under ar-
gon atmosphere. After being stirred for 15 min, a solution of 23
(538 mg, 1.20 mmol) in DMF (2 mL) was added. After being stirred
for 1 h at 90 °C, the reaction mixture was quenched with aqueous
NH4Cl and extracted with Et2O. The organic layer was washed with
water and brine, dried over Na2SO4 and concentrated in vacuo. The
resultant residue was purified by column chromatography on silica
gel (EtOAc/hexane/, 1/7) to yield 24 (375 mg, 95%) as a pale yellow
oil. 1H NMR (200 MHz, CDCl3) d 8.01 (d, J = 16 Hz, 1H), 7.50 (dd,
J = 7.5, 1.7 Hz, 1H), 7.31 (m, 1H), 7.00–6.86 (m, 2H), 6.51 (d,
J = 16 Hz, 1H), 4.86 (s, 2H), 4.37–4.15 (m, 2H), 3.80 (s, 3H), 3.62
(s, 3H), 2.65 (t, J = 6.8 Hz, 2H), 2.32–1.79 (m, 4H), 2.19 (s, 3H),
2.16 (s, 3H), 2.10 (s, 3H), 1.36 (s, 3H).
The titled compound was synthesized in the same manner as
described for 24 using 26 instead of 22 as a colorless oil. Yield
86%; 1H NMR (200 MHz, CDCl3) d 10.27 (s, 1H), 7.80 (dd, J = 8.8,
1.0 Hz, 1H), 6.58 (m, 1H), 6.54 (m, 1H), 4.86 (s, 2H), 4.35–4.25
(m, 2H), 3.85 (s, 3H), 3.61 (s, 3H), 2.70–2.58 (m, 2H), 2.32–2.02
(m, 2H), 2.19 (s, 3H), 2.16 (s, 3H), 2.09 (s, 3H), 1.98–1.82 (m, 2H),
1.36 (s, 3H).
5.1.7. (2E)-3-{2-[2-(6-Hydroxy-2,5,7,8-tetramethyl-3,4-dihydro-
2H-chromen-2-yl)ethoxy]-4-methoxyphenyl}acrylic acid (8)
The titled compound was synthesized in the same manner as
described for 7 using 28 instead of 27 as a white powder. Yield
40% in two steps; 1H NMR (300 MHz, CDCl3) d 8.01 (d, J = 16 Hz,
1H), 7.47 (d, J = 8.4 Hz, 1H), 6.50 (dd, J = 8.4, 2.4 Hz, 1H), 6.45 (d,
J = 2.4 Hz, 1H), 6.40 (d, J = 16 Hz, 1H), 4.33–4.13 (m, 2H), 3.82 (s,
3H), 2.75–2.60 (m, 2H), 2.30–2.05 (m, 2H), 2.16 (s, 3H), 2.12 (s,
3H), 2.11 (s, 3H), 2.00–1.80 (m, 2H), 1.36 (s, 3H); IR (KBr) 1685,
1603, 1265, 1212, 1162, 1119, 833 cmꢀ1; MS (APCI, Neg.) m/e
425 (MꢀH)ꢀ; HRMS (Neg.) calcd for C25H29O6: 425.1964; found:
425.1969.
5.1.3. (2E)-3-{2-[2-(6-Hydroxy-2,5,7,8-tetramethyl-3,4-dihydro-
2H-chromen-2-yl)ethoxy]phenyl}acrylic acid (6)
Toa stirred solution of 24 (356 mg, 0.783 mmol) inTHF (3 mL) and
MeOH (2 mL) was added 2 M NaOH (1 mL). After being stirred for 4 h
at room temperature, the reaction mixture was neutralized with 1 M
HCl and extracted with EtOAc. The organic layer was washed with
water and brine, dried over Na2SO4 and concentrated in vacuo. The
resultant residue was diluted with dioxane (1 mL) and then treated
with 4 M HCl indioxane (1 mL). After beingstirred for 30 min, the sol-
vent was removed by evaporation to yield 6 (229 mg, 74% in two
steps) as a beige powder. 1H NMR (300 MHz, CDCl3) d 8.09 (d,
J = 16 Hz, 1H), 7.53 (dd, J = 7.7, 1.7 Hz, 1H), 7.34 (m, 1H), 7.01–6.88
(m, 2H), 6.52 (d, J = 16 Hz, 1H), 4.36–4.18 (m, 2H), 2.68 (t, J = 6.9 Hz,
2H), 2.32–2.03 (m, 2H), 2.16 (s, 3H), 2.12 (s, 3H), 2.11 (s, 3H), 2.02–
1.82 (m, 2H), 1.37 (s, 3H); IR (KBr) 3441, 2932, 1686, 1626, 1598,
1493, 1457, 1418, 1307, 1241, 1167, 1109, 1086, 1021, 988, 929,
873, 752 cmꢀ1; MS (APCI, Neg.) m/e 395 (MꢀH)ꢀ; HRMS (Neg.) calcd
for C24H27O5: 395.1858; found: 395.1856.
5.1.8. 3-(Methoxymethoxy)benzylalcohol (30)
To a stirred solution of NaH (62.7% in oil, 6.78 g, 0.177 mol) in DMF
(100 mL) was added 29 (20.0 g, 0.161 mol) in DMF (150 mL) at 0 °C
underargon atmosphere. Afterbeing stirred for15 min, chloromethyl
methyl ether (14.7 mL, 0.193 mol) in DMF (10 mL) was added drop-
wise. After being stirred for 15 min at ambient temperature, the reac-
tion mixture wasquenched with water and extracted with EtOAc. The
organic layer was washed with water and brine, and dried over
MgSO4. Concentration invacuoprovided30(22.4 g,77%)asapaleyel-
low oil. 1H NMR (200 MHz, CDCl3) d 7.28 (t, J = 7.9 Hz, 1H), 7.09–6.92
(m, 3H), 5.19 (s, 2H), 4.67 (s, 2H), 3.48 (s, 3H).
5.1.9. 4-Formyl-3-(methoxymethoxy)benzyl acetate (31)
5.1.4. 2-{2-[6-(Methoxymethoxy)-2,5,7,8-tetramethyl-3,4-
dihydro-2H-chromen-2-yl]ethoxy}-4-methylbenzaldehyde (27)
The titled compound was synthesized in the same manner as
described for 24 using 25 instead of 22 as a pale yellow oil. Yield
64%; 1H NMR (200 MHz, CDCl3) d 10.37 (d, J = 0.6 Hz, 1H), 7.69
(d, J = 7.9 Hz, 1H), 6.82 (d, J = 7.9 Hz, 1H), 6.76 (s, 1H), 4.86 (s,
2H), 4.40–4.19 (m, 2H), 3.62 (s, 3H), 2.65 (m, 2H), 2.37 (s, 3H),
2.29–2.06 (m, 2H), 2.19 (s, 3H), 2.16 (s, 3H), 2.10 (s, 3H), 1.97–
1.84 (m, 2H), 1.36 (s, 3H).
To a stirred solution of 30 (21.2 g, 0.126 mol), N,N,N0,N0-tetram-
ethylethylene diamine (TMEDA) (41.8 mL, 0.277 mol) in Et2O
(350 mL),were added dropwise n-butylithium (1.53 M in hexane,
82.4 mL, 0.126 mol) and t-butyllithium (1.51 M, in pentane,
100 mL, 0.151 mol) below ꢀ70 °C under argon atmosphere. The
reaction mixture was allowed to warm to ꢀ40 °C over 1 h and stir-
red for an additional 15 min at ꢀ40 °C. To this mixture was added
N-formylpiperidine (28 mL, 0.252 mol) in Et2O (30 mL) at ꢀ65 °C.
The resultant mixture was allowed to warm to room temperature
over 2 h, quenched with aqueous NH4Cl and then extracted with
EtOAc. The organic layer was washed with water and brine, dried
over MgSO4 and concentrated in vacuo. Purification by column
chromatography on silica gel (EtOAc/hexane, 1/2–3/1) provided a
yellow oil including N-formylpiperidine, which was treated with
acetic anhydride (100 mL) in pyridine (100 mL) at 0 °C. After being
stirred for 20 min, the reaction mixture was quenched with water
and extracted with EtOAc. The organic layer was washed with
water and brine, dried over MgSO4 and concentrated in vacuo.
The resultant residue was purified by column chromatography
on silica gel (EtOAc/hexane, 1/4) to yield 31 (11.9 g, 40% in two
steps) as a pale yellow oil. 1H NMR (200 MHz, CDCl3) d 10.47 (d,
J = 0.8 Hz, 1H), 7.84 (d, J = 8.0 Hz, 1H), 7.19 (s, 1H), 7.06 (m, 1H),
5.32 (s, 2H), 5.12 (s, 2H), 3.54 (s, 3H), 2.15 (s, 3H).
5.1.5. (2E)-3-{2-[2-(6-Hydroxy-2,5,7,8-tetramethyl-3,4-dihydro-
2H-chromen-2-yl)ethoxy]-4-methylphenyl}acrylic acid (7)
A solution of 27 (225 mg, 0.545 mmol), malonic acid (99 mg,
0.954 mmol), piperidine (0.100 mL) in pyridine (2 mL) was stirred
for 1 h at 100 °C. The reaction mixture was diluted with water and
extracted with EtOAc. The organic layer was washed with water
and brine, dried over MgSO4 and concentrated in vacuo. The resul-
tant residue was dissolved dioxane (1 mL) and then 4 M HCl in diox-
ane (1 mL) was added. After concentration in vacuo to remove the
solvent, the resultant residue was recrystallized from MeOH–CHCl3
to yield 7 (98 mg, 45% in two steps) as an off-white powder. 1H NMR
(300 MHz, DMSO-d6) d 12.19 (br s, 1H), 7.78 (d, J = 16 Hz, 1H), 7.53
(d, J = 8.0 Hz, 1H), 7.40 (s, 1H), 6.87 (s, 1H), 6.77 (d, J = 8.0 Hz, 1H),
6.43 (d, J = 16 Hz, 1H), 4.26 (m, 1H), 4.16 (m, 1H), 2.58–2.53 (m,
2H), 2.28 (s, 3H), 2.10–1.96 (m, 2H), 2.04 (s, 3H), 2.01 (s, 3H), 2.00
(s, 3H), 1.92–1.74 (m, 2H), 1.28 (s, 3H); IR (KBr) 3471, 3200, 2932,
1690, 1627, 1456, 1378, 1315, 1292, 1251, 1157, 1086, 1029, 989,
966, 932, 813, 662 cmꢀ1; MS (APCI, Neg.) m/e 409 (MꢀH)ꢀ; HRMS
(Neg.) calcd for C25H29O5: 409.2015; found: 409.2032.
5.1.10. Ethyl (2E)-3-[4-[(acetyloxy)methyl]-2-
(methoxymethoxy)phenyl]acrylate (32)
To a stirred solution of ethyl diethylphosphonoacetate (5.50 g,
24.6 mmol) in THF (80 mL) was added NaH (62.7% in oil, 942 mg,

6576
M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
24.6 mmol) at 0 °C under argon atmosphere. After being stirred for
30 min at room temperature, 31 (4.50 g, 18.9 mmol) in THF
(50 mL) was slowly added. The resultant mixture was stirred for
1 h at room temperature, quenched with water and extracted with
EtOAc. The organic layer was washed with water and brine, dried
over MgSO4 and concentrated in vacuo. The resultant residue
was purified by column chromatography on silica gel (EtOAc/hex-
ane, 1/3–1/1) to yield 32 (5.11 g, 88%) as a pale yellow oil. 1H NMR
(200 MHz, CDCl3) d 8.00 (d, J = 16 Hz, 1H), 7.52 (d, J = 8.0 Hz, 1H),
7.14 (s, 1H), 7.01 (d, J = 8.0 Hz, 1H), 6.51 (d, J = 16 Hz, 1H), 5.27
(s, 2H), 5.08 (s, 2H), 4.26 (q, J = 7.1 Hz, 2H), 3.51 (s, 3H), 2.12 (s,
3H), 1.34 (t, J = 7.1 Hz, 3H).
under argon atmosphere. After being stirred for 15 min, a solution
of 3-phenoxypropyl bromide (181 mg, 0.843 mmol) in DMF (1 mL)
was added. After being stirred for 1.5 h at 90 °C, the reaction mix-
ture was quenched with aqueous NH4Cl and extracted with Et2O.
The organic layer was washed with water and brine, dried over
Na2SO4 and concentrated in vacuo. The resultant residue was puri-
fied by column chromatography on silica gel (CHCl3/MeOH, 25/1)
to yield 36 (164 mg, 72%) as a pale yellow oil. 1H NMR (200 MHz,
CDCl3) d 7.95 (d, J = 16 Hz, 1H), 7.55 (s, 1H), 7.48 (d, J = 7.8 Hz,
1H), 7.35–7.21 (m, 2H), 7.11 (s, 1H), 7.00–6.85 (m, 4H), 6.77–6.63
(m, 2H), 6.50 (d, J = 16 Hz, 1H), 5.08 (s, 2H), 4.33–4.09 (m, 6H),
2.39–2.23 (m, 2H), 1.32 (t, J = 7.1 Hz, 3H).
5.1.15. (2E)-3-[4-(1H-Imidazol-1-ylmethyl)-2-(3-
5.1.11. Ethyl (2E)-3-[4-(hydroxymethyl)-2-
phenoxypropoxy)phenyl]acrylic acid hydrochloride (9)
To a solution of 36 (158 mg, 0.389 mmol) in THF (1.5 mL) and
MeOH (1 mL) was added 2 M NaOH (0.5 mL). After being stirred
for 3 h at 50 °C, the reaction mixture was neutralized with 1 M
HCl and extracted with EtOAc. The organic layer was washed with
brine, dried over Na2SO4 and concentrated in vacuo. The resultant
residue was triturated with MeOH–THF–Et2O. The obtained pow-
der was treated with 4 M HCl in dioxane (2 mL) to afforded 9
(80 mg, 50% in two steps) as a pale yellow powder. 1H NMR
(300 MHz, DMSO-d6) d 9.29 (m, 1H), 7.80 (d, J = 16 Hz, 1H), 7.79
(m, 1H), 7.71 (d, J = 7.8 Hz, 1H), 7.67 (m, 1H), 7.32–7.22 (m, 3H),
7.04–6.88 (m, 4H), 6.55 (d, J = 16 Hz, 1H), 5.41 (s, 2H), 4.24 (t,
J = 6.2 Hz, 2H), 4.15 (t, J = 6.1 Hz, 2H), 2.24 (m, 2H); IR (KCl) 3423,
3035, 1688, 1629, 1601, 1568, 1438, 1322, 1296, 1271, 1242,
1206, 1175, 1064, 990, 764, 727, 697 cmꢀ1; MS (APCI, Neg.) m/e
377 (MꢀH)ꢀ; HRMS (Pos.) calcd for C22H23N2O4: 379.1658; found:
379.1658.
(methoxymethoxy)phenyl]acrylate (33)
To a stirred solution of 32 (750 mg, 2.43 mmol) in EtOH (8 mL)
was added sodium ethoxide (330 mg, 4.86 mmol) at 0 °C under ar-
gon atmosphere. After being stirred for 30 min at room tempera-
ture, the reaction mixture was poured into ice-cold water and
then extracted with EtOAc. The organic layer was washed with
water and brine, dried over MgSO4 and concentrated in vacuo.
The resultant residue was purified by column chromatography
on silica gel (EtOAc/hexane, 2/3–1/1) to yield 33 (562 mg, 87%)
as a pale yellow oil. 1H NMR (200 MHz, CDCl3) d 8.01 (d,
J = 16 Hz, 1H), 7.52 (d, J = 7.8 Hz, 1H), 7.17 (m, 1H), 7.00 (m, 1H),
6.49 (d, J = 16 Hz, 1H), 5.27 (s, 2H), 4.70 (s, 2H), 4.27 (q,
J = 7.1 Hz, 2H), 3.50 (s, 3H), 1.34 (t, J = 7.1 Hz, 3H).
5.1.12. Ethyl (2E)-3-[4-(1H-imidazol-1-ylmethyl)-2-
(methoxymethoxy)phenyl]acrylate (34)
To a stirred solution of 33 (558 mg, 2.09 mmol) and TEA
(0.350 mL, 2.51 mmol) in THF (7 mL) was added methanesulfonyl
chloride (0.180 mL, 2.31 mmol) at 0 °C under argon atmosphere.
After being stirred for 20 min, the reaction mixture was diluted
with EtOAc, washed with water and brine, dried over MgSO4 and
concentrated in vacuo. The obtained residue was treated with
imidazole (770 mg, 11.3 mmol) in toluene (3 mL) under argon
atmosphere. After being stirred for 3 h at 80 °C, the reaction mix-
ture was quenched with aqueous NaHCO3 and extracted with
EtOAc. The organic layer was washed with water and brine, dried
over MgSO4 and concentrated in vacuo. The resultant residue
was purified by column chromatography on silica gel (CHCl3/
MeOH, 80/1) to yield 34 (617 mg, 86% in two steps) as a white so-
lid. 1H NMR (200 MHz, CDCl3) d 7.97 (d, J = 16 Hz, 1H), 7.56 (s, 1H),
7.50 (d, J = 8.0 Hz, 1H), 7.11 (m, 1H), 7.04–6.88 (m, 2H), 6.75 (m,
1H), 6.48 (d, J = 16 Hz, 1H), 5.22 (s, 2H), 5.11 (s, 2H), 4.27 (q,
J = 7.1 Hz, 2H), 3.49 (s, 3H), 1.34 (t, J = 7.1 Hz, 3H).
5.1.16. Ethyl (2E)-3-[4-(1H-imidazol-1-ylmethyl)-2-(4-
phenoxybutoxy)phenyl]acrylate (37)
The titled compound was synthesized in the same manner as
described for 36 using 4-phenoxybutyl bromide instead of 3-phen-
oxypropyl bromide as a yellow solid. Yield 92% in two steps; 1H
NMR (200 MHz, CDCl3) d 7.99 (d, J = 16 Hz, 1H), 7.55 (s, 1H), 7.49
(d, J = 7.6 Hz, 1H), 7.35–7.21 (m, 2H), 6.99–6.86 (m, 5H), 6.80–
6.60 (m, 2H), 6.52 (d, J = 16 Hz, 1H), 4.69 (s, 2H), 4.25 (q,
J = 7.1 Hz, 2H), 4.13 (t, J = 5.9 Hz, 2H), 4.05 (t, J = 5.8 Hz, 2H),
2.17–1.90 (m, 4H), 1.32 (t, J = 7.1 Hz, 3H).
5.1.17. (2E)-3-[4-(1H-Imidazol-1-ylmethyl)-2-(4-
phenoxybutoxy)phenyl]acrylic acid hydrochloride (10)
The titled compound was synthesized in the same manner as
described for 9 as a pale yellow powder. Yield 42% in two steps;
1H NMR (300 MHz, DMSO-d6) d 9.29 (m, 1H), 7.81 (m, 1H), 7.80
(d, J = 16 Hz, 1H), 7.71 (d, J = 7.8 Hz, 1H), 7.67 (m, 1H), 7.32–7.21
(m, 3H), 7.04–6.86 (m, 4H), 6.57 (d, J = 16 Hz, 1H), 5.41 (s, 2H),
4.15 (t, J = 5.7 Hz, 2H), 4.03 (t, J = 6.0 Hz, 2H), 2.02–1.81 (m, 4H);
IR (KCl) 3423, 3035, 1688, 1629, 1601, 1568, 1438, 1322, 1296,
1271, 1242, 1206, 1175, 1064, 990, 764, 727, 697 cmꢀ1; MS (APCI,
Neg.) m/e 391 (MꢀH)ꢀ; HRMS (Pos.) calcd for C23H25N2O4:
393.1814; found: 393.1800.
5.1.13. Ethyl (2E)-3-[2-hydroxy-4-(1H-imidazol-1-
ylmethyl)phenyl]acrylate (35)
To a stirred solution of 34 (615 mg, 1.94 mmol) in EtOH (4 mL)
was added 4 M HCl in dioxane (2 mL). After being stirred for 2 h,
the reaction mixture was neutralized with aqueous NaHCO3 and
extracted with EtOAc. The organic layer was washed with water
and brine, dried over MgSO4. Concentration in vacuo provided 35
(434 mg, 82%) as a white powder. 1H NMR (200 MHz, CDCl3) d
7.97 (d, J = 16 Hz, 1H), 7.54 (s, 1H), 7.44 (d, J = 7.8 Hz, 1H), 7.01
(s, 1H), 6.92 (s, 1H), 6.74 (d, J = 8.2 Hz, 1H), 6.67 (d, J = 16 Hz,
1H), 6.36 (s, 1H), 5.12 (s, 2H), 4.24 (q, J = 7.2 Hz, 2H), 3.78 (s, 1H),
1.32 (t, J = 7.2 Hz, 3H).
5.1.18. (2E)-3-[2-[2-(1-Benzofuran-2-yl)ethoxy]-4-(1H-
imidazol-1-ylmethyl)phenyl]acrylic acid hydrochloride (11)
To a stirred solution of 35 (145 mg, 0.532 mmol), 2-(benzofu-
ran-2-yl)ethanol
0.936 mmol) in THF (2 mL) was added DEAD (1.6 M in toluene,
126 L, 0.936 mmol) at room temperature. After being stirred for
(104 mg,
0.638 mmol),
Ph3P
(209 mg,
l
5.1.14. Ethyl (2E)-3-[4-(1H-imidazol-1-ylmethyl)-2-(3-
phenoxypropoxy)phenyl]acrylate (36)
To a stirred solution of 35 (153 mg, 0.562 mmol) in DMF
(1.5 mL) was added NaH (62.7% in oil, 26 mg, 0.674 mmol) at 0 °C
12 h, the reaction mixture was concentrated in vacuo and purified
by column chromatography on silica gel (CHCl3/MeOH, 100/1) to
yield 38 which was hydrolyzed with 2 M NaOH (0.5 mL) in THF
(1.5 mL) and MeOH (1 mL). After being stirred for 2 h at 50 °C,

M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
6577
the reaction mixture was neutralized with 1 M HCl and extracted
with EtOAc. The organic layer was washed with brine, dried over
Na2SO4 and concentrated in vacuo. After purification by column
chromatography on silica gel (CHCl3/MeOH, 100/1–9/1), the ob-
tained residue was treated with 4 M HCl in dioxane (2 mL) to yield
11 (53 mg, 23% in three steps) as a white powder. 1H NMR
(300 MHz, DMSO-d6) d 9.28 (s, 1H), 7.84–7.65 (m, 4H), 7.58–7.47
(m, 2H), 7.31 (s, 1H), 7.27–7.15 (m, 2H), 7.00 (d, J = 8.1 Hz, 1H),
6.73 (s, 1H), 6.57 (d, J = 16 Hz, 1H), 5.41 (s, 2H), 4.41 (t, J = 6.3 Hz,
2H), 3.34 (t, J = 6.3 Hz, 2H); IR (KCl) 3423, 3037, 2823, 1686,
1611, 1576, 1455, 1435, 1302, 1269, 1173, 1118, 1085, 1032,
992, 751, 660, 635 cmꢀ1; MS (APCI, Neg.) m/e 387 (MꢀH)ꢀ; HRMS
(Pos.) calcd for C23H21N2O4: 389.1501; found: 389.1503.
oil. Yield 85% in two steps; 1H NMR (200 MHz, CDCl3) d 8.01 (d,
J = 16 Hz, 1H), 7.54 (d, J = 7.9 Hz, 1H), 7.36–7.21 (m, 3H), 7.10
(dd, J = 7.9, 1.1 Hz, 1H), 7.02–6.92 (m, 3H), 6.50 (d, J = 16 Hz, 1H),
5.27 (s, 2H), 5.05 (s, 2H), 4.27 (q, J = 7.2 Hz, 2H), 3.50 (s, 3H), 1.34
(t, J = 7.2 Hz, 3H).
5.1.23. Methyl 2-hydroxy-4-iodobenzoate (44)
To a stirred solution of 43 (5.00 g, 32.6 mmol) in 14% H2SO4
was added sodium nitrite (2.40 g, 34.8 mmol) in water (10 mL)
at 0 °C. After being stirred for 10 min, potassium iodide (8.70 g,
52.4 mmol) in water (20 mL) was added and the reaction mixture
was stirred for 1 h at 60 °C. After cooling to the room tempera-
ture, the mixture was filtered through a pad of Celite and the fil-
trate was extracted with Et2O. The organic layer was washed
successively with aqueous Na2S2O3, water and brine, dried over
MgSO4 and concentrated in vacuo. The resultant residue was trea-
ted with concd H2SO4 (2.5 mL) in MeOH (70 mL). After being stir-
red for 3 days, the reaction mixture was concentrated to half the
volume and then poured into ice-cold water. The mixture was
extracted with Et2O and the organic layer was washed with water
and brine, dried over MgSO4 and concentrated in vacuo. The
resultant residue was purified by column chromatography on sil-
ica gel (EtOAc/hexane, 1/20) to yield 44 (3.26 g, 36% in two steps)
as a white powder. 1H NMR (200 MHz, CDCl3) d 10.74 (s, 1H), 7.50
(d, J = 8.6 Hz, 1H), 7.41 (d, J = 1.6 Hz, 1H), 7.24 (dd, J = 8.6, 1.6 Hz,
1H), 3.95 (s, 3H).
5.1.19. (2E)-3-{4-(1H-Imidazol-1-ylmethyl)-2-[2-(2-
naphthyl)ethoxy]phenyl}acrylic acid hydrochloride (12)
The titled compound was synthesized in the same manner as de-
scribed for 11 using 2-(naphthalen-2-yl)ethanol instead of 2-(ben-
zofuran-2-yl)ethanol as a white powder. Yield 38% in three steps;
1H NMR (300 MHz, DMSO-d6) d 9.28 (m, 1H), 7.92–7.77 (m, 6H),
7.72–7.64 (m, 2H), 7.56–7.42 (m, 3H), 7.27 (s, 1H), 6.98 (d,
J = 7.8 Hz, 1H), 6.55 (d, J = 16 Hz, 1H), 5.39 (s, 2H), 4.35 (t,
J = 6.6 Hz, 2H), 3.27 (t, J = 6.6 Hz, 2H); IR (KCl) 3041, 2825, 1685,
1608, 1576, 1504, 1435, 1391, 1366, 1271, 1172, 1118, 1086, 1024,
987, 847, 808, 746, 660, 636 cmꢀ1; MS (APCI, Neg.) m/e 397 (MꢀH)
ꢀ; HRMS (Pos.) calcd for C25H23N2O3: 399.1709; found: 399.1699.
5.1.20. Ethyl (2E)-3-[2-(methoxymethoxy)-4-(1H-pyrazol-1-
ylmethyl)phenyl]acrylate (40)
5.1.24. Methyl 4-iodo-2-(methoxymethoxy)benzoate (45)
The titled compound was synthesized in the same manner as
described for 30 using 44 instead of 29 as a white powder. Yield
99%; 1H NMR (200 MHz, CDCl3) d 7.57 (d, J = 1.4 Hz, 1H), 7.49 (d,
J = 8.0 Hz, 1H), 7.40 (dd, J = 8.0, 1.4 Hz, 1H), 5.23 (s, 2H), 3.89 (s,
3H), 3.52 (s, 3H).
To a stirred solution of 33 (360 mg, 1.34 mmol) and TEA
(0.280 mL, 2.01 mmol) in THF (7 mL) was added methanesulfonyl
chloride (0.130 mL, 1.61 mmol) at 0 °C under argon atmosphere.
After being stirred for 20 min, the reaction mixture was diluted
with EtOAc. The organic layer was washed with water and brine,
dried over MgSO4 and concentrated in vacuo to yield the corre-
sponding methanesulfonate. To a stirred solution of pyrazole
(100 mg, 1.47 mmol) in DMF (7 mL) was added NaH (62.7% in oil,
59 mg, 1.47 mmol) at 0 °C under argon atmosphere. After being
stirred for 1 h, obtained methanesulfonate in DMF (3 mL) was
added at 0 °C and the reaction mixture was stirred for 1 h at ambi-
ent temperature. The mixture was quenched with aqueous NH4Cl
and extracted with EtOAc. The organic layer was washed with
brine, dried over MgSO4 and concentrated in vacuo. The resultant
residue was purified by column chromatography on silica gel
(EtOAc/hexane, 1/4) to yield 40 (215 mg, 50% in two steps) as a col-
orless oil. 1H NMR (200 MHz, CDCl3) d 7.98 (d, J = 16 Hz, 1H), 7.56
(d, J = 1.8 Hz, 1H), 7.48 (d, J = 8.0 Hz, 1H), 7.42 (d, J = 1.8 Hz, 1H),
7.00 (s, 1H), 6.79 (d, J = 8.0 Hz, 1H), 6.47 (d, J = 16 Hz, 1H), 6.30 (t,
J = 1.8 Hz, 1H), 5.31 (s, 2H), 5.22 (s, 2H), 4.26 (q, J = 7.2 Hz, 2H),
3.48 (s, 3H), 1.33 (t, J = 7.2 Hz, 3H).
5.1.25. Methyl 4-benzyl-2-(methoxymethoxy)benzoate (46)
To a stirred solution of 45 (330 mg, 1.02 mmol), DPPF (17 mg,
31.0 lmol) and Pd2(dba)3 (9.0 mg, 15.5 lmol) in THF (1 mL) was
added benzylzinc bromide (1.6 mL, 1.60 mmol), which was pre-
pared from zinc (392 mg, 6.00 mmol) and benzyl bromide
(513 mg, 3.00 mmol) in THF (3 mL) according to the literature14
,
at 0 °C under argon atmosphere. After being stirred for 12 h at
50 °C, the reaction mixture was quenched with aqueous NH4Cl
and extracted with EtOAc. The organic layer was washed with
brine, dried over MgSO4 and concentrated in vacuo. The resultant
residue was purified by column chromatography on silica gel
(EtOAc/hexane, 1/4) to yield 46 (240 mg, 82%) as a colorless oil.
1H NMR (200 MHz, CDCl3) d 7.72 (d, J = 8.0 Hz, 1H), 7.35–7.12 (m,
5H), 7.03 (d, J = 1.4 Hz, 1H), 6.85 (dd, J = 8.0, 1.4 Hz, 1H), 5.22 (s,
2H), 3.98 (s, 2H), 3.87 (s, 3H), 3.51 (s, 3H).
5.1.26. [4-Benzyl-2-(methoxymethoxy)phenyl]methanol (48)
To a stirred suspension of LiAlH4 (41 mg, 1.08 mmol) in THF
(2.5 mL) was added 46 (238 mg, 0.830 mmol) in THF (1.5 mL) at
0 °C. After being stirred for 30 min, aqueous Na2SO4 was added
and the resultant mixture was filtered through a pad of Celite to re-
move the white precipitate. The filtrate was evaporated to yield 48
(206 mg, 96%) as a colorless oil. 1H NMR (200 MHz, CDCl3) d 7.36–
7.14 (m, 6H), 6.95 (s, 1H), 6.83 (d, J = 7.6 Hz, 1H), 5.20 (s, 2H), 4.67
(s, 2H), 3.96 (s, 2H), 3.48 (s, 3H).
5.1.21. Ethyl (2E)-3-{2-(methoxymethoxy)-4-[(2-oxopyrrolidin-
1-yl)methyl]phenyl}acrylate (41)
The titled compound was synthesized in the same manner as
described for 40 using 2-pyrrolidone instead of pyrazole as a
colorless oil. Yield 75% in two steps; 1H NMR (200 MHz, CDCl3)
d 7.99 (d, J = 16 Hz, 1H), 7.49 (d, J = 8.0 Hz, 1H), 7.01 (s, 1H),
6.89 (d, J = 8.0 Hz, 1H), 6.48 (d, J = 16 Hz, 1H), 5.25 (s, 2H),
4.44 (s, 2H), 4.26 (d, J = 7.0 Hz, 2H), 3.50 (s, 3H), 3.29 (t,
J = 7.2 Hz, 2H), 2.46 (t, J = 8.1 Hz, 2H), 2.10–1.94 (m, 2H), 1.34
(t, J = 7.0 Hz, 3H).
5.1.27. Ethyl (2E)-3-[4-benzyl-2-
(methoxymethoxy)phenyl]acrylate (50)
5.1.22. Ethyl (2E)-3-[2-(methoxymethoxy)-4-
(phenoxymethyl)phenyl]acrylate (42)
The titled compound was synthesized in the same manner as
described for 40 using phenol instead of pyrazole as a pale yellow
To a stirred solution of 48 (200 mg, 0.770 mmol) and TEA
(0.530 ml, 3.85 mmol) in DMSO (3.8 mL) and CH2Cl2 (2.5 mL) was
added sulfur trioxide–pyridine complex (616 mg, 3.87 mmol) at
0 °C. After being stirred for 1 h at room temperature, the reaction

6578
M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
mixture was poured into ice-cold water and extracted with Et2O. The
organic layer was washed with brine, dried over MgSO4 and concen-
trated in vacuo to yield the corresponding aldehyde, which was con-
verted into 50 in the same manner as described for 32. Yield 97% in
two steps. 1H NMR (200 MHz, CDCl3) d 7.99 (d, J = 16 Hz, 1H), 7.44
(d, J = 8.0 Hz, 1H), 7.36–7.16 (m, 5H), 7.00 (s, 1H), 6.82 (d,
J = 8.0 Hz, 1H), 6.45 (d, J = 16 Hz, 1H), 5.22 (s, 2H), 4.26 (q,
J = 7.1 Hz, 2H), 3.97 (s, 2H), 3.49 (s, 3H), 1.33 (t, J = 7.1 Hz, 3H).
(m, 2H), 7.03–6.90 (m, 5H), 6.52 (d, J = 16 Hz, 1H), 5.03 (s, 2H),
4.34 (t, J = 7.0 Hz, 2H), 4.27 (q, J = 7.2 Hz, 2H), 3.32 (t, J = 7.0 Hz,
2H), 1.34 (t, J = 7.2 Hz, 3H).
5.1.34. Ethyl (2E)-3-{4-benzyl-2-[2-(2-
naphthyl)ethoxy]phenyl}acrylate (55)
Yield 74% in two steps; 1H NMR (200 MHz, CDCl3) d 7.99 (d,
J = 16 Hz, 1H), 7.86–7.72 (m, 4H), 7.50–7.37 (m, 4H), 7.35–7.12
(m, 5H), 6.77 (d, J = 7.8 Hz, 1H), 6.71 (s, 1H), 6.48 (d, J = 16 Hz,
1H), 4.33–4.20 (m, 4H), 3.94 (s, 2H), 3.29 (t, J = 7.0 Hz, 2H), 1.34
(t, J = 7.2 Hz, 3H).
5.1.28. Methyl 2-(methoxymethoxy)-4-(2-
thienylmethyl)benzoate (47)
The titled compound was synthesized in the same manner as
described for 46 using 2-bromomethylthiophene instead of benzyl
bromide as a pale yellow oil. Yield 57%; 1H NMR (200 MHz, CDCl3)
d 7.76 (d, J = 7.8 Hz, 1H), 7.60–7.36 (m, 2H), 7.19–6.78 (m, 3H), 5.23
(s, 2H), 4.27 (s, 2H), 3.87 (s, 3H), 3.52 (s, 3H).
5.1.35. Ethyl (2E)-3-[2-[2-(2-naphthyl)ethoxy]-4-(2-
thienylmethyl)phenyl]acrylate (56)
Yield 66% in two steps; 1H NMR (200 MHz, CDCl3) d 7.99 (d,
J = 16 Hz, 1H), 7.86–7.73 (m, 4H), 7.50–7.38 (m, 4H), 7.18–7.12
(m, 1H), 6.96–6.76 (m, 4H), 6.50 (d, J = 16 Hz, 1H), 4.34–4.20 (m,
4H), 4.12 (s, 2H), 3.31 (t, J = 6.8 Hz, 2H), 1.34 (t, J = 7.1 Hz, 3H).
5.1.29. [2-(Methoxymethoxy)-4-(2-
thienylmethyl)phenyl]methanol (49)
The titled compound was synthesized in the same manner as
described for 48 using 47 instead of 46 as a colorless oil. Yield
68%; 1H NMR (200 MHz, CDCl3) d 7.36–6.78 (m, 6H), 5.21 (s, 2H),
4.68 (s, 2H), 4.13 (s, 2H), 3.49 (s, 3H).
5.1.36. (2E)-3-[2-[2-(2-Naphthyl)ethoxy]-4-(1H-pyrazol-1-
ylmethyl)phenyl]acrylic acid (4)
To a stirred solution of 52 (445 mg, 1.04 mmol) in THF (3 mL)
and MeOH (3 mL) was added 2 M NaOH (3 mL). After being stirred
for 2 h at 50 °C, the reaction mixture was acidified with 1 M HCl
and extracted with EtOAc. The organic layer was washed with
brine, dried over MgSO4 and concentrated in vacuo. The resultant
residue was purified by column chromatography on silica gel
(EtOAc/hexane, 2/3–3/2) to yield 4 (281 mg, 68%) as a colorless
amorphous. 1H NMR (200 MHz, CDCl3) d 8.07 (d, J = 16 Hz, 1H),
7.88–7.72 (m, 4H), 7.57 (d, J = 2.0 Hz, 1H), 7.51–7.35 (m, 5H),
6.77 (d, J = 7.8 Hz, 1H), 6.72 (s, 1H), 6.51 (d, J = 16 Hz, 1H), 6.29
(t, J = 2.0 Hz, 1H), 5.30 (s, 2H), 4.25 (t, J = 6.6 Hz, 2H), 3.28 (t,
J = 6.6 Hz, 2H); IR (KBr) 1689, 1610, 1431, 1266, 1170, 819, 749,
479 cmꢀ1; MS (APCI, Neg.) m/e 397 (MꢀH)ꢀ; HRMS (Pos.) calcd
for C25H23N2O3: 399.1709; found: 399.1717.
5.1.30. Ethyl (2E)-3-[2-(methoxymethoxy)-4-(2-
thienylmethyl)phenyl]acrylate (51)
The titled compound was synthesized in the same manner as
described for 50 using 49 instead of 48 as a pale yellow oil. Yield
33% in two steps; 1H NMR (200 MHz, CDCl3) d 7.98 (d, J = 16 Hz,
1H), 7.47 (d, J = 7.8 Hz, 1H), 7.16 (dd, J = 5.0, 1.0 Hz, 1H), 6.95 (s,
1H), 6.98–6.79 (m, 3H), 6.47 (d, J = 16 Hz, 1H), 5.23 (s, 2H), 4.25
(q, J = 7.1 Hz, 2H), 4.14 (s, 2H), 3.49 (s, 3H), 1.33 (t, J = 7.1 Hz, 3H).
5.1.31. Ethyl (2E)-3-{2-[2-(2-naphthyl)ethoxy]-4-(1H-pyrazol-
1-ylmethyl)phenyl}acrylate (52)
To a stirred solution of 40 (390 mg, 1.23 mmol) in EtOH (4 mL)
was added 4 M HCl in dioxane (1.5 mL) at room temperature. After
being stirred for 2 h, the reaction mixture was poured into aqueous
NaHCO3 and extracted with EtOAc. The organic layer was washed
with brine, dried over MgSO4 and concentrated in vacuo. The resul-
tant residue was treated with 2-(naphthalen-2-yl)ethanol (224 mg,
1.42 mmol), Ph3P (464 mg, 1.77 mmol) and ADDP (447 mg,
1.77 mmol) in THF (13 mL) at room temperature under argon
atmosphere. After being stirred for 12 h, the reaction mixture
was evaporated and the resultant residue was purified by column
chromatography on silica gel (EtOAc/hexane, 1/1) to yield 52
According to the same procedure as described above, 13, 16, 14
and 15 were prepared from 54, 55, 56 and 57, respectively.
5.1.37. (2E)-3-{2-[2-(2-Naphthyl)ethoxy]-4-[(2-oxopyrrolidin-
1-yl)methyl]phenyl}acrylic acid (13)
Yield 79%; 1H NMR (200 MHz, CDCl3) d 8.10 (d, J = 16 Hz, 1H),
7.90–7.76 (m, 4H), 7.52–7.36 (m, 4H), 6.86–6.76 (m, 2H), 6.54 (d,
J = 16 Hz, 1H), 4.41 (s, 2H), 4.31 (t, J = 6.5 Hz, 2H), 3.32 (t,
J = 6.5 Hz, 2H), 3.24 (t, J = 7.0 Hz, 2H), 2.45 (t, J = 8.0 Hz, 2H),
2.10–1.88 (m, 2H); IR (neat) 1685, 1500, 1429, 1266, 1173,
732 cmꢀ1; MS (APCI, Neg.) m/e 414 (MꢀH)ꢀ; HRMS (Pos.) calcd
for C26H26NO4: 416.1862; found: 416.1840.
(452 mg, 90% in two steps) as
a
pale yellow oil. 1H NMR
(200 MHz, CDCl3) d 7.96 (d, J = 16 Hz, 1H), 7.88–7.70 (m, 4H),
7.58–7.34 (m, 6H), 6.76 (d, J = 8.2 Hz, 1H), 6.70 (s, 1H), 6.49 (d,
J = 16 Hz, 1H), 6.28 (t, J = 4.2 Hz, 1H), 5.28 (s, 2H), 4.35–4.15 (m,
4H), 3.29 (t, J = 6.6 Hz, 2H), 1.34 (t, J = 7.2 Hz, 3H).
5.1.38. (2E)-3-{2-[2-(2-Naphthyl)ethoxy]-4-
(phenoxymethyl)phenyl}acrylic acid (16)
Yield 86%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, J = 16 Hz, 1H),
7.87–7.76 (m, 4H), 7.57–7.39 (m, 4H), 7.34–7.24 (m, 2H), 7.06–
6.92 (m, 5H), 6.56 (d, J = 16 Hz, 1H), 5.05 (s, 2H), 4.35 (t,
J = 6.8 Hz, 2H), 3.33 (t, J = 6.8 Hz, 2H); IR (KBr) 3427, 2947, 1690,
1624, 1598, 1497, 1433, 1379, 1329, 1239, 1220, 1118, 1036,
991, 822, 750, 692, 481 cmꢀ1; MS (APCI, Neg.) m/e 423 (MꢀH)ꢀ;
HRMS (Neg.) calcd for C28H23O4: 423.1596; found: 423.1599.
According to the same procedure as described above, 53–56
were prepared from 41, 42, 50 and 51, respectively.
5.1.32. Ethyl (2E)-3-{2-[2-(2-naphthyl)ethoxy]-4-[(2-
oxopyrrolidin-1-yl)methyl]phenyl}acrylate (53)
Yield 23% in two steps; 1H NMR (200 MHz, CDCl3) d 7.98 (d,
J = 16 Hz, 1H), 7.86–7.74 (m, 4H), 7.52–7.36 (m, 4H), 6.84–6.74
(m, 2H), 6.51 (d, J = 16 Hz, 1H), 4.39 (s, 2H), 4.35–4.22 (m, 4H),
3.32 (t, J = 6.8 Hz, 2H), 3.23 (t, J = 7.2 Hz, 2H), 2.42 (t, J = 8.1 Hz,
2H), 2.06–1.88 (m, 2H), 1.35 (t, J = 7.2 Hz, 3H).
5.1.39. (2E)-3-{4-Benzyl-2-[2-(2-
naphthyl)ethoxy]phenyl}acrylic acid (14)
Yield 86%; 1H NMR (200 MHz, CDCl3) d 8.12 (d, J = 16 Hz, 1H),
7.88–7.74 (m, 4H), 7.52–7.10 (m, 9H), 6.79 (d, J = 8.0 Hz, 1H),
6.72 (s, 1H), 6.52 (d, J = 16 Hz, 1H), 4.26 (t, J = 6.6 Hz, 2H), 3.95 (s,
2H), 3.29 (t, J = 6.6 Hz, 2H); IR (KBr) 3026, 1678, 1615, 1418,
1263, 1209, 1020, 820, 700, 477 cmꢀ1; MS (APCI, Neg.) m/e 407
5.1.33. Ethyl (2E)-3-[2-[2-(2-naphthyl)ethoxy]-4-
(phenoxymethyl)phenyl]acrylate (54)
Yield 69% in two steps; 1H NMR (200 MHz, CDCl3) d 8.00 (d,
J = 16 Hz, 1H), 7.86–7.74 (m, 4H), 7.53–7.40 (m, 4H), 7.35–7.21

M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
6579
(MꢀH)ꢀ; HRMS (Neg.) calcd for C28H23O3: 407.1647; found:
(200 MHz, CDCl3) d 10.31 (d, J = 0.8 Hz, 1H), 7.86–7.70 (m, 5H),
7.53–7.31 (m, 8H), 6.60 (dd, J = 8.7, 1.5 Hz, 1H), 6.51 (d, J = 2.1 Hz,
1H), 5.08 (s, 2H), 4.32 (t, J = 6.6 Hz, 2H), 3.30 (t, J = 6.6 Hz, 2H).
407.1655.
5.1.40. (2E)-3-[2-[2-(2-Naphthyl)ethoxy]-4-(thien-2-
ylmethyl)phenyl]acrylic acid (15)
5.1.45. (2E)-3-{4-(Benzyloxy)-2-[2-(2-
Yield 61%; 1H NMR (300 MHz, CDCl3) d 8.12 (d, J = 16 Hz, 1H),
7.86–7.74 (m, 4H), 7.50–7.38 (m, 4H), 7.15 (dd, J = 5.1, 1.2 Hz,
1H), 6.92 (dd, J = 5.1, 3.6 Hz, 1H), 6.84 (d, J = 7.5 Hz, 1H), 6.82–
6.76 (m, 2H), 6.53 (d, J = 16 Hz, 1H), 4.29 (t, J = 6.8 Hz, 2H), 4.12
(s, 2H), 3.31 (t, J = 6.8 Hz, 2H); IR (KBr) 1665, 1606, 1435, 1318,
1285, 1258, 1211, 814, 744, 706 cmꢀ1; MS (APCI, Neg.) m/e 413
(MꢀH)ꢀ; HRMS (Neg.) calcd for C26H21O3S: 413.1211; found:
413.1217.
naphthyl)ethoxy]phenyl}acrylic acid (17)
A solution of 60 (288 mg, 0.753 mmol), malonic acid (141 mg,
1.36 mmol), piperidine (0.100 mL) in pyridine (3 mL) was stirred
for 1 h at 100 °C. The reaction mixture was quenched with water
and extracted with EtOAc. The organic layer was washed with
water and brine, dried over MgSO4 and concentrated in vacuo.
The resultant residue was recrystallized from EtOAc–hexane to
yield 17 (292 mg, 91%) as
a
pale yellow powder. 1H NMR
(300 MHz, CDCl3) d 8.06 (d, J = 16 Hz, 1H), 7.87–7.76 (m, 4H),
7.50–7.29 (m, 9H), 6.60–6.51 (m, 2H), 6.46 (d, J = 16 Hz, 1H), 5.05
(s, 2H), 4.29 (t, J = 6.8 Hz, 2H), 3.33 (t, J = 6.8 Hz, 2H); IR (KBr)
3038, 2935, 1682, 1600, 1567, 1504, 1321, 1263, 1208, 1181,
1117, 1027, 815, 742, 699, 619, 476 cmꢀ1; MS (APCI, Neg.) m/e
423 (MꢀH)ꢀ; HRMS (Neg.) calcd for C28H23O4: 423.1596; found:
423.1608.
5.1.41. Ethyl 3-[2-[2-(2-naphthyl)ethoxy]-4-(1H-pyrazol-1-
ylmethyl)phenyl]propanoate (57)
To a stirred solution of 52 (1.97 g, 4.62 mmol), NiCl2–6H2O
(1.21 g, 5.08 mmol) in THF (32 mL) and EtOH (8 mL) was added
NaBH4 (699 mg, 18.5 mmol) at 0 °C under argon atmosphere. After
being stirred for 1 h at ambient temperature, the reaction mixture
was quenched with water and filtered through a pad of Celite. The
filtrate was extracted with EtOAc and the organic layer was
washed with brine, dried over Na2SO4 and concentrated in vacuo.
The resultant residue was purified by column chromatography
on silica gel (EtOAc/hexane, 2/3) to yield 57 (1.61 g, 81%) as a col-
orless oil. 1H NMR (300 MHz, CDCl3) d 7.84–7.76 (m, 3H), 7.72 (s,
1H), 7.53 (d, J = 2.1 Hz, 1H), 7.49–7.38 (m, 3H), 7.35 (d, J = 2.1 Hz,
1H), 7.08 (d, J = 7.2 Hz, 1H), 6.73–6.65 (m, 2H), 6.26 (t, J = 2.1 Hz,
1H), 5.24 (s, 2H), 4.20 (t, J = 6.6 Hz, 2H), 4.09 (q, J = 7.1 Hz, 2H),
3.23 (t, J = 6.6 Hz, 2H), 2.87 (t, J = 7.7 Hz, 2H), 2.47 (t, J = 7.7 Hz,
2H) 1.22 (t, J = 7.1 Hz, 3H).
5.1.46. 3-[2-(2-Naphthyl)ethoxy]-4-nitrobenzaldehyde (62)
The titled compound was synthesized in the same manner as
described for 60 using 61 instead of 59 as a white powder. Yield
30%; 1H NMR (200 MHz, CDCl3) d 9.98 (s, 1H), 7.93–7.74 (m, 5H),
7.55–7.38 (m, 5H), 4.45 (t, J = 6.6 Hz, 2H), 3.33 (t, J = 6.6 Hz, 2H).
5.1.47. 4-Hydroxy-3-[2-(2-naphthyl)ethoxy]benzaldehyde (63)
To a stirred solution of benzaldoxime (565 mg, 4.66 mmol) in
DMSO (10 mL) was added potassium t-butoxide (522 mg,
4.66 mmol) at 0 °C under argon atmosphere. After being stirred
for 20 min, 62 (680 mg, 2.12 mmol) in DMSO (5 mL) was added
and then the reaction mixture was stirred for 2 h. The mixture
was poured into 1 M HCl and extracted with Et2O. The organic
layer was washed with brine, dried over MgSO4 and concentrated
in vacuo. The resultant residue was purified by column chromatog-
raphy on silica gel (EtOAc/hexane, 1/4) to yield 63 (297 mg, 48%) as
a pale yellow oil. 1H NMR (200 MHz, CDCl3) d 9.81 (s, 1H), 7.96–
7.76 (m, 3H), 7.72 (s, 1H), 7.54–7.36 (m, 6H), 7.01 (d, J = 8.4 Hz,
1H), 4.45 (t, J = 6.8 Hz, 2H), 3.32 (t, J = 6.8 Hz, 2H).
5.1.42. 3-[2-[2-(2-Naphthyl)ethoxy]-4-(1H-pyrazol-1-
ylmethyl)phenyl]propanoic acid (5)
The titled compound was synthesized in the same manner as
described for 4 using 57 instead of 52 as a white powder. Yield
99%; 1H NMR (300 MHz, CDCl3) d 7.82–7.75 (m, 3H), 7.71 (s, 1H),
7.54 (d, J = 2.1 Hz, 1H), 7.48–7.32 (m, 4H), 7.08 (d, J = 7.8 Hz, 1H),
6.73–6.66 (m, 2H), 6.26 (t, J = 2.1 Hz, 1H), 5.24 (s, 2H), 4.20 (t,
J = 6.6 Hz, 2H), 3.23 (t, J = 6.6 Hz, 2H), 2.87 (t, J = 7.7 Hz, 2H), 2.51
(t, J = 7.7 Hz, 2H); IR (KBr) 3048, 2930, 2878, 1709, 1613, 1582,
1508, 1427, 1261, 1211, 1194, 1124, 1034, 820, 770, 754, 619,
cmꢀ1; MS (APCI, Neg.) m/e 399 (MꢀH)ꢀ; HRMS (Pos.) calcd for
C25H25N2O3: 401.1865; found: 401.1880.
5.1.48. 4-(Hydroxymethyl)-2-[2-(2-naphthyl)ethoxy]phenol
(64)
To a stirred solution of 63 (297 mg, 1.02 mmol) in EtOH (5 mL)
was added NaBH4 (46 mg, 1.22 mmol) at 0 °C. After being stirred
for 1 h, the reaction mixture was quenched with acetic acid and
then poured into water. The mixture was extracted with EtOAc
and the organic layer was washed with brine, dried over MgSO4
and concentrated in vacuo. The resultant residue was purified
by column chromatography on silica gel (EtOAc/hexane, 1/2) to
yield 64 (188 mg, 63%) as a yellow powder. 1H NMR (200 MHz,
CDCl3) d 7.78–7.68 (m, 4H), 7.54–7.36 (m, 3H), 6.96–6.80 (m,
3H), 5.52 (s, 1H), 4.58 (s, 2H), 4.38 (t, J = 6.9 Hz, 2H), 3.29 (t,
J = 6.9 Hz, 2H).
5.1.43. 4-(Benzyloxy)-2-hydroxybenzaldehyde (59)
A
solution of 58 (1.04 g, 7.50 mmol), NaHCO3 (725 mg,
8.63 mmol), KI (125 mg, 0.750 mmol) benzyl chloride (1.12 mL,
9.75 mmol) in acetonitrile (7 mL) was refluxed for 20 h under argon
atmosphere. The reaction mixture was quenched with water at 0 °C
and extracted with Et2O. The organic layer was washed with water
andbrine, driedover MgSO4 andconcentratedinvacuo. Theresultant
residuewaspurified bycolumn chromatography onsilicagel(EtOAc/
hexane, 1/3) to yield 59 (1.30 g, 76%) as an off-white solid. 1H NMR
(200 MHz, CDCl3) d 11.47 (s, 1H), 9.72 (s, 1H), 7.45–7.32 (m, 6H),
6.61 (dd, J = 8.6, 2.4 Hz, 1H), 6.51 (d, J = 2.4 Hz, 1H), 5.11 (s, 2H).
5.1.49. Ethyl {4-(hydroxymethyl)-2-[2-(2-
naphthyl)ethoxy]phenoxy}acetate (65)
5.1.44. 4-(Benzyloxy)-2-[2-(2-naphthyl)ethoxy]benzaldehyde
(60)
To a stirred solution of 64 (188 mg, 0.640 mmol) in DMF (4 mL)
was added NaH (62.7% in oil, 25 mg, 0.670 mmol) at 0 °C under ar-
gon atmosphere. After being stirred for 1 h, ethyl bromoacetate
(0.100 mL, 0.770 mmol) was added and the reaction mixture was
stirred for 30 min at room temperature. The mixture was quenched
with aqueous NH4Cl and extracted with EtOAc. The organic layer
was washed with brine, dried over MgSO4 and concentrated in va-
cuo. The resultant residue was purified by column chromatography
on silica gel (EtOAc/hexane, 2/3) to yield 65 (211 mg, 87%) as a pale
To a stirred solution of 59 (400 mg, 1.75 mmol), 2-(naphthalen-
2-yl)ethanol (362 mg, 2.10 mmol), Ph3P (690 mg, 2.63 mmol) in
THF (5 mL) was added ADDP (662 mg, 2.63 mmol) at room temper-
ature under argon atmosphere. After being stirred for 12 h, the
reaction mixture was concentrated in vacuo. The resultant residue
was purified by column chromatography on silica gel (EtOAc/hex-
ane, 1/5) to yield 60 (486 mg, 73%) as a pale yellow solid. 1H NMR

6580
M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
yellow oil. 1H NMR (200 MHz, CDCl3) d 7.86–7.73 (m, 4H), 7.52–
7.38 (m, 3H), 6.97–6.79 (m, 3H), 4.62–4.55 (m, 4H), 4.33 (t,
J = 7.1 Hz, 2H), 4.22 (q, J = 7.4 Hz, 2H), 3.31 (t, J = 7.1 Hz, 2H), 1.27
(t, J = 7.4 Hz, 3H).
7.78 (m, 4H), 7.72 (d, J = 8.0 Hz, 1H), 7.51 (dd, J = 8.6, 1.7 Hz, 1H).
7.48–7.41 (m, 2H), 6.83 (d, J = 2.0 Hz, 1H), 6.67 (dd, J = 8.0, 2.0 Hz,
1H), 4.62 (d, J = 5.7 Hz, 2H), 4.31 (t, J = 6.6 Hz, 2H), 3.33 (t,
J = 6.6 Hz, 2H).
5.1.50. Ethyl [2-[2-(2-naphthyl)ethoxy]-4-(1H-pyrazol-1-
ylmethyl)phenoxy] acetate (66)
5.1.55. 1-{4-Iodo-3-[2-(2-naphthyl)ethoxy]benzyl}-1H-pyrazole
(71)
To a stirred solution of 65 (70 mg, 0.184 mmol) in CH2Cl2 (1 mL)
was added phosphorus tribromide (26 lL, 0.276 mmol) at 0 °C un-
The titled compound was synthesized in the same manner as
described for 40 using 70 instead of 33 as a colorless oil. Yield
87% in two steps; 1H NMR (300 MHz, CDCl3) d 7.85–7.77 (m, 4H),
7.70 (d, J = 8.0 Hz, 1H), 7.51 (d, J = 2.1 Hz, 1H), 7.51–7.40 (m, 3H),
7.34 (d, J = 2.1 Hz, 1H), 6.59 (d, J = 1.9 Hz, 1H), 6.54 (dd, J = 8.0,
1.9 Hz, 1H), 6.26 (t, J = 2.1 Hz, 1H), 5.22 (s, 2H), 4.19 (t, J = 6.6 Hz,
2H), 3.28 (t, J = 6.6 Hz, 2H).
der argon atmosphere. After being stirred for 10 min, the reaction
mixture was quenched with water and diluted with EtOAc. The
mixture was washed with water and brine, dried over MgSO4
and concentrated in vacuo to yield the corresponding bromide,
which was used for the next step without purification. To a stirred
solution of pyrazole (19 mg, 0.276 mmol) in DMF (0.5 mL) was
added NaH (62.7% in oil, 11 mg, 0.276 mmol) at room temperature
under argon atmosphere. After being stirred for 30 min, the ob-
tained bromide in DMF (1.5 mL) was added and the reaction mix-
ture was stirred for 1 h at room temperature. The mixture was
quenched with aqueous NH4Cl and extracted with Et2O. The organ-
ic layer was washed with brine, dried over MgSO4 and concen-
trated in vacuo. The resultant residue was purified by column
chromatography on silica gel (EtOAc/hexane, 2/3) to yield 66
5.1.56. 3-{[2-(2-Naphthyl)ethoxy]-4-(1H-pyrazol-1-
ylmethyl)phenyl}prop-2-yn-1-ol (72)
A solution of 71 (1.50 g, 3.18 mmol), propargyl alcohol (370 lL,
6.36 mmol), CuI (30 mg, 0.159 mmol), PdCl2(Ph3P)2 (112 mg,
0.159 mmol), tetrabutylammonium iodide (59 mg, 0.159 mmol),
TEA (1.27 mL, 9.11 mmol) in DMF (7 mL) was stirred at 75 °C for
3 h under argon atmosphere. The reaction mixture was diluted
with Et2O and water, and then filtered through a pad of Celite.
The filtrate was separated and the organic layer was washed with
water and brine, dried over Na2SO4 and concentrated in vacuo. The
resultant residue was purified by column chromatography on silica
gel (EtOAc/hexane, 1/1) to yield 72 (495 mg, 37%) as a yellow oil.
1H NMR (300 MHz, CDCl3) d 7.85–7.72 (m, 4H), 7.55 (d, J = 2.1 Hz,
1H), 7.51–7.31 (m, 5H), 6.71 (d, J = 7.8 Hz, 1H), 6.67 (s, 1H), 6.28
(t, J = 2.1 Hz, 1H), 5.27 (s, 2H), 4.46 (d, J = 6.3 Hz, 2H), 4.25 (t,
J = 6.6 Hz, 2H), 3.26 (t, J = 6.6 Hz, 2H).
(30 mg, 38% in two steps) as
a
pale yellow oil. 1H NMR
(200 MHz, CDCl3) d 7.86–7.70 (m, 4H), 7.61 (d, J = 2.1 Hz, 1H),
7.50–7.37 (m, 4H), 6.88–6.70 (m, 3H), 6.25 (t, J = 2.1 Hz, 1H), 5.21
(s, 2H), 4.58 (s, 2H), 4.26 (t, J = 7.2 Hz, 2H), 4.22 (q, J = 7.2 Hz,
2H), 3.28 (t, J = 7.2 Hz, 2H), 1.26 (t, J = 7.2 Hz, 3H).
5.1.51. [2-[2-(2-Naphthyl)ethoxy]-4-(1H-pyrazol-1-
ylmethyl)phenoxy]acetic acid (19)
The titled compound was synthesized in the same manner as
described for 4 using 66 instead of 52 as a colorless amorphous.
Yield 35%; 1H NMR (300 MHz, CDCl3) d 7.83–7.75 (m, 3H), 7.70
(s, 1H), 7.55 (dd, J = 1.8, 0.6 Hz, 1H), 7.49–7.32 (m, 4H), 6.84 (d,
J = 7.8 Hz, 1H), 6.78–6.71 (m, 2H), 6.26 (t, J = 2.1 Hz, 1H), 5.22 (s,
2H), 4.59 (s, 2H), 4.25 (t, J = 7.1 Hz, 2H), 3.25 (t, J = 7.1 Hz, 2H); IR
(KBr) 2929, 1733, 1515, 1434, 1260, 1212, 1143, 1063, 1030, 858,
820, 753, 667, 621, 479 cmꢀ1; MS (APCI, Neg.) m/e 401 (MꢀH)ꢀ;
HRMS (Pos.) calcd for C24H23N2O4: 403.1658; found: 403.1660.
5.1.57. 3-{2-[2-(2-Naphthyl)ethoxy]-4-(1H-pyrazol-1-
ylmethyl)phenyl}prop-2-ynoic acid (18)
To a stirred solution of 72 (349 mg, 0.870 mmol) in CH2Cl2
(4 mL) was added Dess–Martin periodinate (738 mg, 1.74 mmol)
at 0 °C. After being stirred for 4 h, the reaction mixture was
quenched with aqueous Na2S2O3 and aqueous NaHCO3, and then
stirred for an additional 30 min. The mixture was extracted with
EtOAc and the organic layer was washed with water and brine,
dried over MgSO4 and concentrated in vacuo to afford 73, which
was used for the next step without purification. To a stirred solu-
tion of 73 and 2-methyl-2-butene (7 mL) in t-BuOH (7 mL) were
added NaH2PO4 (163 mg, 1.04 mmol) in water (7 mL) and NaClO2
(157 mg, 1.74 mmol). After being stirred for 12 h, 1 M HCl was
added and the mixture was extracted with EtOAc. The organic
layer was washed with water and brine, dried over Na2SO4 and
concentrated in vacuo. The resultant residue was recrystallized
with EtOAc–hexane to afford 18 (150 mg, 44% in two steps) as a
white powder. 1H NMR (300 MHz, CD3OD) d 7.85–7.73 (m, 4H),
7.66 (d, J = 2.3 Hz, 1H), 7.54–7.49 (m, 2H), 7.44–7.34 (m, 3H),
6.78 (s, 1H), 6.71 (dd, J = 7.8, 1.5 Hz, 1H), 6.31 (t, J = 2.3 Hz, 1H),
5.30 (s, 2H), 4.24 (t, J = 6.5 Hz, 2H), 3.23 (t, J = 6.5 Hz, 2H); IR
5.1.52. Methyl 3-hydroxy-4-iodobenzoate (68)
The titled compound was synthesized in the same manner as
described for 44 using 67 instead of 43 as a pale brown powder.
Yield 68%; 1H NMR (300 MHz, CDCl3) d 7.75 (d, J = 8.1 Hz, 1H),
7.63 (d, J = 2.0 Hz, 1H), 7.37 (dd, J = 8.1, 2.0 Hz, 1H), 5.50 (s, 1H),
3.91 (s, 3H).
5.1.53. Methyl 4-iodo-3-[2-(2-naphthyl)ethoxy]benzoate (69)
The titled compound was synthesized in the same manner as
described for 60 using 68 instead of 59 as a colorless oil. Yield
99%; 1H NMR (300 MHz, CDCl3) d 7.86–7.78 (m, 5H), 7.51 (dd,
J = 8.4, 1.5 Hz, 1H), 7.49–7.43 (m, 2H), 7.40 (d, J = 1.7 Hz, 1H),
7.35 (dd, J = 8.1, 1.7 Hz, 1H), 4.35 (t, J = 6.6 Hz, 2H), 3.88 (s, 3H),
3.34 (t, J = 6.6 Hz, 2H).
(KBr) 3363, 2923, 2209, 1563, 1505, 1428, 1393, 1289, 753 cmꢀ1
;
MS (FAB, Pos.) m/e 397 (M+H)+; HRMS (Pos.) calcd for
C25H21N2O3: 397.1552; found: 397.1556.
5.1.54. {4-Iodo-3-[2-(2-naphthyl)ethoxy]phenyl}methanol (70)
To a stirred solution of 69 (4.61 g, 10.7 mmol) in CH2Cl2 (40 mL)
was added diisobutylaluminum hydride (0.95 M in hexane,
28.0 mL, 26.7 mmol) at ꢀ70 °C under argon atmosphere. The reac-
tion mixture was allowed to warm to ꢀ40 °C over 1 h and then
quenched with aqueous Na2SO4. The resultant mixture was filtered
through a pad of Celite to remove the precipitate and the filtrate
was evaporated. The resultant residue was purified by column
chromatography on silica gel (EtOAc/hexane, 1/4–1/3) to yield 70
(4.21 g, 97%) as a colorless oil. 1H NMR (300 MHz, CDCl3) d 7.85–
5.1.58. Ethyl 4-[2-[2-(2-naphthyl)ethoxy]-4-(1H-pyrazol-1-
ylmethyl)phenyl]butanoate (74)
To a stirred solution of 71 (120 mg, 0.264 mmol), PdCl2(dppf)
(22 mg, 26.4 lmol) in THF (0.5 mL) was added 4-ethoxy-4-oxobu-
tylzinc bromide (0.5 M in THF, 2.11 mL, 1.06 mmol) at room temper-
ature under argon atmosphere. After being stirred for 12 h at 50 °C,
the reaction mixture was quenched with 1 M HCl at 0 °C and ex-
tracted with EtOAc. The organic layer was washed with water and
brine, dried over Na2SO4 and concentrated in vacuo. The resultant

M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
6581
residue was purified by column chromatography on silica gel
(EtOAc/hexane, 1/1) to yield 74 (94 mg, 80%) as a brown oil. 1H
NMR (300 MHz, CDCl3) d 7.83–7.75 (m, 3H), 7.70 (s, 1H), 7.52 (d,
J = 2.1 Hz, 1H), 7.49–7.37 (m, 3H), 7.33, (d, J = 2.1 Hz, 1H), 7.04 (d,
J = 7.6 Hz, 1H), 6.71 (dd, J = 7.6, 1.7 Hz, 1H), 6.66 (d, J = 1.5 Hz, 1H),
6.25 (t, J = 2.1 Hz, 1H), 5.24 (s, 2H), 4.19 (t, J = 6.7 Hz, 2H), 4.08 (q,
J = 7.1 Hz, 2H), 3.23 (t, J = 6.7 Hz, 2H), 2.56 (t, J = 7.5 Hz, 2H), 2.20
(t, J = 7.5 Hz, 2H), 1.83–1.74 (m, 2H), 1.23 (t, J = 7.1 Hz, 3H).
perature and the reaction mixture was stirred for 12 h. Concentra-
tion in vacuo followed by purification by column chromatography
on silica gel (CHCl3/MeOH, 50/1) afforded 21 (93 mg, 45%) as an iv-
ory powder. 1H NMR (300 MHz, CDCl3) d 7.86–7.80 (m, 3H), 7.68 (s,
1H), 7.56–7.23 (m, 6H), 6.80–6.74 (m, 2H), 6.28 (m, 1H), 5.29 (s,
2H), 4.52 (s, 2H), 4.26 (t, J = 6.9 Hz, 2H), 4.01 (s, 2H), 3.23 (t,
J = 6.9 Hz, 2H); IR (KBr) 3105, 2902, 2520, 1732, 1613, 1586,
1507, 1430, 1400, 1263, 1216, 1159, 1136, 1110, 1065, 1040,
965, 866, 817, 753, 624 cmꢀ1; MS (APCI, Neg.) m/e 415 (MꢀH)ꢀ;
HRMS (Pos.) calcd for C25H25N2O4: 417.1814; found: 417.1795.
5.1.59. 4-[2-[2-(2-Naphthyl)ethoxy]-4-(1H-pyrazol-1-
ylmethyl)phenyl]butanoic acid (20)
5.2. Pharmacology
The titled compound was synthesized in the same manner as de-
scribed for 4 using 74 instead of 52 as a white powder. Yield 85%; 1H
NMR (200 MHz, CDCl3) d 7.84–7.73 (m, 3H), 7.69 (s, 1H), 7.54 (d,
J = 1.6 Hz, 1H), 7.50–7.32 (m, 4H), 7.02 (d, J = 7.6 Hz, 1H), 6.74–
6.64 (m, 2H), 6.25 (t, J = 2.1 Hz, 1H), 5.24 (s, 2H), 4.18 (t, J = 6.6 Hz,
2H), 3.21 (t, J = 6.6 Hz, 2H), 2.57 (t, J = 7.5 Hz, 2H), 2.20 (t,
J = 7.4 Hz, 2H), 1.88–1.68 (m, 2H); IR (KBr) 1708, 1510, 1427, 1273,
1145, 1041, 821, 760, 623 cmꢀ1; MS (APCI, Neg.) m/e 413 (MꢀH)ꢀ;
HRMS (Pos.) calcd for C26H27N2O3: 415.2022; found: 415.2014.
5.2.1. Measurement of the prostanoid mEP1-4 receptors
binding assay
Competitive binding studies were conducted using radiolabeled
ligands and membrane fractions prepared from Chinese hamster
ovary (CHO) cells stably expressing the prostanoid receptors
mEP1-4. Membranes from CHO cells expressing prostanoid recep-
tors were incubated with radiolabeled ligand (2.5 nM [3H]PGE2)
and test compounds at various concentrations in assay buffer
(10 mM KH2PO4–KOH buffer containing 1 mM EDTA, 10 mM MgCl2
and 0.1 mM NaCl, pH 6.0). Incubation was carried out at 25 °C for
60 min except for mEP1 that was incubated for 20 min. Incubation
was terminated by filtration through a Whatman GF/B filter. The
filter was subsequently washed with ice-cold buffer (10 mM
KH2PO4–KOH buffer containing 0.1 mM NaCl, pH 6.0), and the
radioactivity on the filter was measured in 6 mL of liquid scintilla-
tion (ACSII) mixture with a liquid scintillation counter. Nonspecific
binding was achieved by adding excess amounts of unlabeled PGE2
in assay buffer. The half maximal inhibitory concentration of spe-
cific binding (IC50 value) was estimated from the regression curve.
The Ki value (M) was calculated according to the following
equation.
5.1.60. Methyl 2-[2-(2-naphthyl)ethoxy]-4-(1H-pyrazol-1-
ylmethyl)benzoate (75)
A solution of 71 (2.29 g, 5.04 mmol), TEA (2.10 mL, 15.0 mmol),
DPPF (139 mg, 0.250 mmol) Pd(OAc)2 (57 mg, 0.250 mmol) in DMF
(5 mL) and MeOH (5 mL) was stirred for 12 h at 60 °C under carbon
monoxide atmosphere. The mixture was diluted with EtOAc and
water, and then filtered through a pad of Celite. The filtrate was ex-
tracted with EtOAc and the organic layer was washed with water
and brine, dried over MgSO4 and evaporated. The resultant residue
was purified by column chromatography on silica gel (EtOAc/hex-
ane, 1/1) to yield 75 (2.10 g, 99%) as a pale yellow oil. 1H NMR
(300 MHz, CDCl3) d 7.83–7.73 (m, 5H), 7.55 (m, 1H), 7.47–7.42
(m, 3H), 7.36 (m, 1H), 6.77 (dd, J = 8.1, 1.5 Hz, 1H), 6.73 (s, 1H),
6.29 (t, J = 2.1 Hz, 1H), 5.30 (s, 2H), 4.25 (t, J = 6.9 Hz, 2H), 3.84 (s,
3H), 3.27 (t, J = 6.9 Hz, 2H).
Ki ¼ IC50=ðl þ ½Lꢁ=KdÞ
[L]: Concentration of radiolabeled ligand. Kd; Dissociation constant
of radiolabeled ligand for the prostanoid receptors.
5.1.61. {[2-(2-Naphthyl)ethoxy]-4-(1H-pyrazol-1-
ylmethyl)phenyl}methanol (76)
5.2.2. Measurement of the mEP3 receptor antagonist activity
To confirm that test compounds antagonized the mEP3 receptor
and estimate potencies of antagonism for the mEP3 receptor, a
functional assay was performed by measuring PGE2-stimulated in-
The titled compound was synthesized in the same manner as
described for 48 using 75 instead of 46 as a colorless oil. Yield
92%; 1H NMR (300 MHz, CDCl3) d 7.83–7.79 (m, 3H), 7.71 (s, 1H),
7.54–7.35 (m, 5H), 7.20 (d, J = 7.2 Hz, 1H), 6.78 (d, J = 7.2 Hz, 1H),
6.72 (s, 1H), 6.27 (t, J = 2.1 Hz, 1H), 5.27 (s, 2H), 4.58 (d,
J = 6.0 Hz, 2H), 4.27 (t, J = 6.6 Hz, 2H), 3.25 (t, J = 6.6 Hz, 2H).
creases in intracellular Ca2+. The cells expressing mEP3
a receptor
were seeded at 1 ꢂ 104 cells/well in 96 well plates and cultured
for 2 days with 10% FBS (fetal bovine serum)/minimum essential
medium Eagle alpha modification (
5% CO2). The cells in each well were rinsed with phosphate buffer
(PBS(ꢀ)), and load buffer (10% FBS/ MEM containing 5 M of Fura
2/AM, 20 M of indomethacin, 2.5 mM of probenecid) was added.
aMEM) in an incubator (37 °C,
5.1.62. tert-Butyl {[2-[2-(2-naphthyl)ethoxy]-4-(1H-pyrazol-1-
ylmethyl)benzyl]oxy}acetate (77)
To a stirred solution of 76 (200 mg, 0.561 mmol), t-butyl bro-
moacetate (0.250 mL. 1.70 mmol), tetrabutylammonium hydrogen
a
l
l
After incubation for 1 h, the cells in each well were rinsed with as-
say buffer(Hank0s balanced salt solution (HBSS) containing 0.1%
sulfate (19 mg, 56.0 lmol) in toluene (1 mL) was added 40% NaOH
(1 mL) at room temperature. After being stirred for 10 h, the reac-
tion mixture was extracted with EtOAc. The organic layer was
washed with water and brine, dried over MgSO4 and concentrated
in vacuo. The resultant residue was purified by column chromatog-
raphy on silica gel (EtOAc/hexane, 1/1) to yield 77 (231 mg, 87%) as
a colorless oil. 1H NMR (300 MHz, CDCl3) d7.83–7.70 (m, 4H), 7.54–
7.34 (m, 6H), 6.81 (dd, J = 7.8, 1.5 Hz, 1H), 6.69 (d, J = 1.5 Hz, 1H),
6.26 (t, J = 2.1 Hz, 1H), 5.27 (s, 2H), 4.58 (s, 2H), 4.21 (t, J = 6.6 Hz,
2H), 3.94 (s, 2H), 3.23 (t, J = 6.6 Hz, 2H), 1.47 (s, 9H).
(w/v) BSA, 2
10 mM of HEPES-NaOH) twice. Then 90
added to each well and the cells were incubated in the dark at
room temperature for 1 h. After the addition of a solution contain-
l
M of indomethacin, 2.5 mM of probenecid and
lL of assay buffer was
ing test compound (30 lL) and PGE2 (30 lL), which were prepared
with an assay buffer, intracellular calcium concentration was
measured with a Fluorescence drug screening system (FDSS-
3000, Hamamatsu Photonics). The fluorescence intensities emitted
500 nm by an excitation wavelength of 340 nm and 380 nm was
measured. The percent inhibition on the increase of the
intracellular Ca2+ concentration induced by PGE2 (10 nM) was cal-
culated relative to the maximum Ca2+ concentration that occurred
in the absence of the test compound (100%) to estimate the IC50
value.
5.1.63. {[2-[2-(2-Naphthyl)ethoxy]-4-(1H-pyrazol-1-
ylmethyl)benzyl]oxy}acetic acid (21)
To a solution of 77 (231 mg, 0.489 mmol), anisole (0.1 mL) in
CH2Cl2 (2 mL) was added trifluoroacetic acid (0.2 mL) at room tem-

6582
M. Asada et al. / Bioorg. Med. Chem. 17 (2009) 6567–6582
Bioorg. Med. Chem. Lett. 2003, 13, 3813; (e) Belley, M.; Gallant, M.; Roy, B.;
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