Synthesis and structure-activity relationships of 5-phenylthiophenecarboxylic acid derivatives as antirheumatic agents

Article abstract of DOI:10.1016/j.bmc.2003.08.009

5-(Phenylthiophene)-3-carboxylic acid (2a), a metabolite of esonarimod (1), which was developed as a new antirheumatic drug, was considered as a lead compound for new antirheumatic drugs. A new series of 2a derivatives were synthesized and their characteristic pharmacological effects, that is their antagonistic effect toward interleukin (IL)-1 in mice and the suppressive effect against adjuvant-induced arthritis (AIA) in rats, were evaluated and compared with those of 1. The structure-activity relationships indicated that [5-(4-bromophenyl)-thiophen-3-yl]acetic acid (5d), methyl [5-(4-chlorophenyl)-thiophen-3-yl]acetate (5h), and methyl [5-(4-bromophenyl)-thiophen-3-yl]acetate (5i) suppressed AIA more potently than 1 and all of the other synthesized compounds.

Full text of DOI:10.1016/j.bmc.2003.08.009

Bioorganic & Medicinal Chemistry 11 (2003) 4729–4742
Synthesis and Structure–Activity Relationships of
5-Phenylthiophenecarboxylic Acid Derivatives as
Antirheumatic Agents
Toshiya Noguchi,* Masahiro Hasegawa, Kazuyuki Tomisawa and Morihiro Mitsukuchi
Medicinal Research Laboratories, Taisho Pharmaceutical Co., Ltd., 403, Yoshino-cho, 1-chome, Kita-ku, Saitama-city,
Saitama 330-8530, Japan
Received 7 May 2003;accepted 5 August 2003
Abstract—5-(Phenylthiophene)-3-carboxylic acid (2a), a metabolite of esonarimod (1), which was developed as a new antirheumatic
drug, was considered as a lead compound for new antirheumatic drugs. A new series of 2a derivatives were synthesized and their
characteristic pharmacological effects, that is their antagonistic effect toward interleukin (IL)-1 in mice and the suppressive effect
against adjuvant-induced arthritis (AIA) in rats, were evaluated and compared with those of 1. The structure–activity relationships
indicated that [5-(4-bromophenyl)-thiophen-3-yl]acetic acid (5d), methyl [5-(4-chlorophenyl)-thiophen-3-yl]acetate (5h), and methyl
[5-(4-bromophenyl)-thiophen-3-yl]acetate (5i) suppressed AIA more potently than 1 and all of the other synthesized compounds.
# 2003 Elsevier Ltd. All rights reserved.
Introduction
these compounds are illustrated in Figure 2. In connec-
tion with these reports, we were interested in the activity
of (5-phenylthiophene)acetic acid derivatives and (5-
phenylthiophene)propionic acid derivatives (5–9).
Esonarimod, (R,S)-2-acetylthiomethyl-4-(4-methylphe-
nyl)-4-oxobutanoic acid (1), was originally developed by
Taisho Pharmaceutical Co. Ltd. as a new antirheumatic
drug.1,2 Compound 1 has a variety of effects on cellular
and mediator events in inflammatory processes, inhibits
the production of inflammatory cytokines including
interleukin (IL)-1, IL-6, and tumor necrosis factor-a
from human peripheral blood mononuclear cells,3 and
suppresses the development of arthritis in various ani-
mal models.1,3ꢀ5 In preclinical and clinical studies, its
metabolic fate has been studied in several animal species
and in humans.6 We found that 5-(4-methylphenyl)-
thiophene-3-carboxylic acid (2a) was a metabolite of 1
that had immunological activity like 1. The chemical
structures of 1 and 2a are shown in Figure 1. These
structural and biological similarities led us to study
derivatives of 2a in the hope of finding new antirheu-
matic agents. Some thiopheneacetic acid derivatives,
such as thiaprofenoic acid (3), have already been devel-
oped as nonsteroidal anti-inflammatory drugs.7 Fur-
thermore, thiophenealkanoic acid (4) has been reported
to exhibit immunological activity.8 The structures of
In this report, we describe the synthesis of new chemi-
cally modified phenylthiophene derivatives, examine
their immunological effects, and discuss the structure–
activity relationships (SARs).
Chemistry
The structures of the prepared compounds 2, 5–9 are
illustrated in Figure 3. Compounds 2 were 5-phenyl-3-
carboxylic acid derivatives. Compounds 5–9 were (5-
phenylthiophen-3-yl)acetic acid, 3-(5-phenylthiophen-3-
yl)propionic acid, 5-phenylthiophene-2-carboxylic acid,
(5-phenylthiophen-2-yl)acetic acid, and 2-(5-phe-
*Corresponding author. Tel.: +81-48-663-1111;e-mail: t.noguchi@
po.rd.taisho.co.jp
Figure 1.
0968-0896/$ - see front matter # 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2003.08.009

4730
T. Noguchi et al. / Bioorg. Med. Chem. 11 (2003) 4729–4742
The preparation of 5-phenylthiophene-2-carboxylic acid
(7a) and its methyl ester (7b) is shown in Scheme 2. The
rhodanine adduct, 5-cinnamylidenerhodanine (14), was
prepared by known methods.16 Hydrolysis and treat-
ment of 14 with H2O2 gave the disulfide (15). Oxidation
of 15 with iodine gave 7a. Treatment with H2SO4 and
methanol gave 7b. The synthetic pathway to other 5-
phenylthiophene-2-carboxylic acid derivatives (7c–h) is
outlined in Scheme 3. 2-Phenylthiophene derivatives
(20a–c) were obtained by three-step reactions from the
corresponding benzene derivatives (16a–c). Vilsmeier
reaction of 20a–c with N,N-dimethylformamide (DMF)
and POCl3 gave aldehydes (21a–c), which were oxidized
to the target compounds (7c–e) with Ag2O.17 Treatment
of 7c–e with H2SO4 and methanol gave the correspond-
ing methyl esters (7f–h).
Figure 2.
nylthiophen-3-yl)propionic acid derivatives, respec-
tively. Compounds 2, 5, 6 and 9 were newly synthesized.
Compounds 7 and 8 were previously known and their
anti-inflammatory and hypolipidemic activities have
been described previously, while their immunological
effects have not been reported.9ꢀ14
5-Phenylthiophene-3-carboxylic acid derivatives (2a–v)
were synthesized from 2-acetylthiomethyl-4-phenyl-4-
oxobutanoic acid derivatives (1, 10a–g), which were
obtained previously by our group (Scheme 1),2 as start-
ing materials. Treatment of 1, 10a–g with H2SO4 and
alcohol gave the corresponding esters of dihy-
drothiophene derivatives (11a–l),6 which were oxidized
with 2,3-dihydro-5,6-dicyano-1,4-benzoquinone (DDQ)
to give esters of 5-phenylthiophene-3-carboxylic acid
derivatives (2b–m).15 Hydrolysis of 2b–m gave free car-
boxylic acid derivatives (2a,n–t). Benzyl or isopropyl
esters of 5-(4-bromophenylthiophene)-3-carboxylic
acids (2u,v) were obtained by esterification of 2p with
the corresponding bromide.
Scheme 4 shows the synthetic route to (5-phenylthio-
phen-3-yl)acetic acid derivatives (5a–i).18 Condensation
of 2-phenylthiolan-4-on (24) with cyanoacetic acid and
then decarbonylation with DDQ gave (5-phenylthio-
phen-3-yl)acetonitrile (25a). Compound 24 was
obtained by two-step reactions from ethyl cinnamate
(22).19 Reduction of 2b,f,h,l with LiAlH4 and treatment
with SOCl2 gave the corresponding chlorides (26a–d),
which were treated with KCN to give the respective (5-
phenylthiophen-3-yl)acetonitrile derivatives (25b–e).
Compounds 5a–e were obtained by hydrolysis of 25a–e.
Treatment of 5a–e with H2SO4 and methanol gave the
corresponding methyl esters (5f–i).
Figure 3.
Scheme 1. Compounds: 1, X=CH3; 10a, X=H; 10b, X=Cl; 10c, X=Br; 10d, X=CH2CH3; 10e, X=CH(CH3)2; 10f, X=OCH3; 10g, X=cyclo-
hexyl; 11a, X=CH3, R=CH3; 11b, X=CH3, R=CH2CH3; 11c, X=H, R=CH3; 11d, X=H, R=CH2CH3; 11e, X=Cl, R=CH3; 11f, X=Cl,
R=CH2CH3; 11g, X=Br, R=CH3; 11h, X=Br, R=CH2CH3; 11i, X=CH2CH3, R=CH3; 11j, X=CH(CH3)2, R=CH3; 11k, X=OCH3, R=CH3;
11l, X=cyclohexyl, R=CH3; 2b, X=CH3, R=CH3; 2c, X=CH3, R=CH2CH3; 2d, X=H, R=CH3; 2e, X=H, R=CH2CH3; 2f, X=Cl, R=CH3;
2g, X=Cl, R=CH2CH3, 2h, X=Br, R=CH3; 2i, X=Br, R=CH2CH3; 2j, X=CH2CH3, R=CH3; 2k, X=CH(CH3)2, R=CH3; 2l, X=OCH3,
R=CH3; 2m, X=cyclohexyl, R=CH3; 2n, X=H; 2a, X=CH3; 2o, X=Cl; 2p, X=Br; 2q, X=CH2CH3; 2r, X=CH(CH3)2; 2s, X=OCH3; 2t,
X=cyclohexyl; 2u, X=Br, R=CH(CH3)2; 2v, X=Br, R=CH2Ph. Reagents and conditions: (a) CH3OH, H2SO4, reflux;(b) CH CH2OH, H2SO4,
3
reflux;(c) DDQ, benzene, rt;(d) KOH, THF, H 2O, rt;(e) PhBr, K 2CO3, DMF, rt;(f) (CH 3)2CHBr, K2CO3, DMF, rt.

T. Noguchi et al. / Bioorg. Med. Chem. 11 (2003) 4729–4742
4731
Scheme 2. Reagents and conditions: (a) AcONa, AcOH, reflux;(b) NaOH, H O, 80 ꢁC;(c) H O2, pyridine, H2O, 3 ꢁC;(d) I , dioxane, ethanol, rt;
(e) H2SO4, CH3OH, reflux.
2
2
2
Scheme 3. Compounds: 16a, X=Cl; 16b, X=Br, 16c, X=CH3; 18a, X=Cl; 18b, X=Br, 18c, X=CH3; 19a, X=Cl; 19b, X=Br, 19c, X=CH3; 20a,
X=Cl; 20b, X=Br, 20c, X=CH3; 21a, X=Cl, 21b, X=Br; 21c, X=CH3; 7c, X=Cl; 7d, X=Br; 7e, X=CH3; 7f, X=Cl, R=CH3; 7g, X=Br,
R=CH3; 7h, X=CH3, R=CH2CH3. Reagents and conditions: (a) AlCl3, CS2, rt;(b) AcSK, DMF, 5 ꢁC;(c) H SO4, CH3OH, reflux;(d) chloranil,
2
benzene, reflux;(e) POCl 3, DMF, 1,2-dichloroethane, reflux;(f) Ag O, NaOH, H2O, 50 ꢁC;(g) H SO4, methanol, toluene, reflux;(h) H SO4, etha-
nol, toluene, reflux.
2
2
2
Scheme 4. Compounds: 26a, X=CH3; 26b, X=Cl; 26c, X=Br; 26d, X=OCH3; 25b, X=CH3; 25c, X=Cl; 25d, X=Br; 25e, X=OCH3; 5a, X=H;
5b, X=CH3; 5c, X=Cl; 5d, X=Br; 5e, X=OCH3; 5f, X=H; 5g, X=CH3; 5h, X=Cl; 5i, X=Br. Reagents and conditions: (a) ethyl thioglycolate,
NaOCH2CH3, ethanol, THF, rt;(b) H 2SO4, acetic acid, H2O, reflux;(c) cyanoacetic acid, acetic acid, piperidine, benzene, reflux;(d) DDQ, toluene,
rt;(e) LiAlH 4, ether, reflux;(f) SOCl 2, THF, [(CH3)2N]3PO, rt;(g) KCN, 18-crown-6, CH 3CN, rt;(h) KOH, ethanol, H 2O, reflux;H 2SO4, methanol,
reflux.

4732
T. Noguchi et al. / Bioorg. Med. Chem. 11 (2003) 4729–4742
Scheme 5. Compounds: 27a, X=Cl; 27b, X=Br; 8a, X=Cl; 8b, X=Br, 8c X=Cl, 8d, X=Br. Reagents and conditions: (a) LiAlH4, (CH3CH2)2O,
reflux;(b) SOCl 2, THF, [(CH3)2N]3PO, rt;(c) KCN, 18-crown-6, CH 3CN, rt;(d) KOH, ethanol, H 2O, reflux;(e) H 2SO4, methanol, reflux.
Scheme 6. Compounds: 28a, X=H; 28b, X=CH3; 28c, X=Cl; 28d, X=Br; 29a, X=H; 29b, X=CH3; 29c, X=Cl; 29d, X=Br; 6a, X=H; 6b,
X=CH3; 6c, X=Cl; 6d, X=Br; 6e, X=H; 6f, X=CH3; 6g, X=Cl; 6h, X=Br. Reagents and conditions;(a) LiAlH 4, ether, reflux;(b) SOCl 2, THF,
[(CH3)2N]3PO, rt;(c) diethyl malonate, NaOCH 2CH3, ethanol, reflux;(d) NaCl, DMSO, H 2O, reflux;(e) NaOH, methanol, H 2O, rf;(f) H 2SO4,
methanol, reflux.
Scheme 7. Compounds: 9a, X=H; 9b, X=Cl; 9c, X=Br; 9d, X=H; 9e, X=Cl; 9f, X=Br. Reagents and conditions: (a) CH3I, NaH, DMF, 0 ꢁC;
(b) KOH, CH3OH, THF, H2O rt.
The same reaction sequence was applied to 7f,g to give
(5-phenylthiophen-2-yl)acetic acid derivatives (8a–d)
(Scheme 5).
on adjuvant-induced arthritis (AIA) in rats. In rheuma-
toid arthritis (RA) patients, IL-1 production is induced
in synovial cells and peripheral blood, and IL-1 elicits
various inflammatory symptoms, such as the prolifera-
tion of synovial cells, stimulation of osteoclasts, and
degradation of cartilage and bone.23,24 AIA is also use-
ful for studies of anti-inflammatory or immunosuppres-
sive effects.25
The preparation of 3-(5-phenylthiophen-3-yl)propionic
acid derivatives (6a–h) is shown in Scheme 6.20 Con-
densation of the chlorides (26a–d), intermediates of 5b–e,
and diethyl malonate with sodium ethoxide gave diesters
(28a–d),21 which were treated with dimethylsulfoxide
(DMSO), NaCl and hydrolysis to give free carboxylic
acids (6a–d), respectively.22 Methyl esters (6e–h) were
obtained from 6a–d with H2SO4 and methanol.
The activities of 2, 5–9 toward IL-1 and AIA are shown
in Tables 1–3. Table 1 shows the results of a SAR study
on the effect of the substituent (X) at the para position
of the phenyl ring and the substituent (R) at the car-
boxylic acid in type 2 compounds, in comparison to the
results with 1. In SAR studies of 1 derivatives, the sub-
stituent on the phenyl ring increased the activity toward
AIA in the order para>meta>ortho.2 Consequently,
the substituent on the phenyl ring was fixed at the para
position in this chemical modification. The effects of 2
with various substituents, that is X=H, CH3, Cl, Br,
The synthesis of 2-(5-phenylthiophen-3-yl)propionic
acid derivatives (9a–f) is shown in Scheme 7.20 Treat-
ment of 5f,h,i with methyl iodide gave 9a–c, which were
hydrolyzed with KOH to give free carboxylic acids (9d–f).
Results and Discussion
cyclohexyl, CH2CH3, and OCH3;R=H, CH
CH2CH3, CH2Ph, and CH(CH3)2, were tested. Type 2
,
3
These compounds were evaluated for their antagonistic
effect toward IL-1 in mice and their suppressive effect
compounds generally showed a slightly stronger IL-1

T. Noguchi et al. / Bioorg. Med. Chem. 11 (2003) 4729–4742
4733
antagonistic effect than 1. Although somewhat less
potent than 1, 2 suppressed AIA when X was halogen.
When X=methyl, 2 was slightly active against AIA, but
other X gave reduced activities. Thus, the antagonistic
effect against IL-1 is dependent on the nature of X: Cl,
Br>CH3> >others. With regard to R, free carboxylic
acid (R=H) and methyl ester (R=CH3) were effective
against AIA. However, ethyl ester, benzyl ester, and
isopropyl ester had less of an effect on AIA. This result
suggests that X=halogen, such as Cl or Br, is potent
against AIA.
Table 3 shows the results of a SAR study on the place-
ment of the carboxylic acid at the 2- and 3-positions of
the thiophene ring (types 2 and 7) and the distance
between the thiophene ring and carboxylic acid (types 5
and 8). Although placement of the carboxylic acid did
not appear to strongly affect the activities, the IL-1
antagonistic effect of type 7 compounds was slightly
greater than that of 1. Type 5 and 8 compounds also
had stronger antagonistic effects toward IL-1 suppres-
sive effects against AIA than 1 or types 2 and 7. How-
ever, type 5 compounds were slightly more potent than
8.
The results of a SAR study on the effect of the distance
between the thiophene ring and carboxylic acid are
shown in Table 2. Compounds of type 2, 5, 6 and 9 were
evaluated. Compounds of type 5 had stronger antag-
onistic effects against IL-1 and suppressed AIA more
than 1 and 2. Compounds 5d, 5h, and 5i were the most
potent of all the synthesized compounds 2, 5–9 against
AIA. On the other hand, compounds of type 6 had
reduced antagonistic effects against IL-1 and suppres-
sive effects against AIA. While type 9 compounds were
active against AIA, they showed no IL-1 antagonistic
effect. These results showed that the distance between
the thiophene ring and carboxylic acid (number of
methylenes=n) was very important for the antagonistic
effect toward IL-1 and the suppression of AIA. The
activities increased in the order n=1, 0, 2. Furthermore,
ramification of methylene was judged invalid.
Conclusion
Several analogues of 2a, a metabolite of esonarimod (1),
which was developed as an antirheumatic agent, were
Table 2. Activities of type 2, 5, 6, and 9 toward IL-1 antagonistic
effect and AIA
Table 1. Activities of type 2 toward IL-1 antagonistic effect and AIA
No.
X
R
IL-1
AIA
IC50 (mM)a % suppressionb Activity rankc
2d
5a
5f
H
H
H
H
H
CH3
H
CH3
H
CH3
H
CH3
H
51.5
26.1
41.0
—
384.5
138.0
212.2
81.1
21.7
79.9
—
69.2
69.9
22.1
26.3
83.2
—
23.7
34.9
5.5
12.1
14.7
ꢀ13.7
50.5
47.8
56.6
89.0
37.9
44.2
57.5
67.1
52.7
48.7
99.7
98.0
38.9
ꢀ2.1
46.7
57.5
—
4
4
1
2
5
—
1
2
0
1
1
0
3
3
4
6
2
3
4
4
3
3
6
6
2
0
3
4
No.
X
R
IL-1
AIA
IC50 (mM)a % suppressionb Activity rankc
6a
6e
9d
9a
2a
2b
5b
5g
6b
6f
H
H
CH3
CH3 CH3
CH3
CH3 CH3
CH3
CH3 CH3
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Br
Br
Br
Br
Br
Br
Br
Br
2a
2b
2c
2d
2e
2o
2f
2g
2p
2h
2i
CH3
CH3
CH3
H
H
Cl
Cl
Cl
Br
Br
H
CH3
CH2CH3
CH3
CH2CH3
H
CH3
CH2CH3
H
CH3
81.1
21.7
—
23.7
34.9
2.5
—
3.2
50.5
47.8
3.3
52.7
48.7
22.5
8.7
24.7
13.1
13.4
13.1
18.4
0
1
2
0
—
0
3
3
0
3
3
1
0
2
1
1
1
1
0
4
51.5
66.7
50.4
34.7
17.2
73.0
63.0
14.8
10.8
—
12.2
2.3
—
—
48.7
105.5
H
24.7
H
135.8
116.9
50.4
34.7
21.0
2o
2f
H
CH3
H
CH3
H
CH3
H
CH3
H
CH3
H
CH3
H
CH3
H
CH3
Br
Br
Br
CH2CH3
CH(CH3)2
PhCH2
H
5c
5h
6c
6g
9e
9b
2p
2h
5d
5i
25.9
2u
2v
103.7
129.3
100.0
78.4
73.0
63.0
29.0
21.8
125.7
161.9
96.0
2t Cyclohexyl
2m Cyclohexyl
2q CH2CH3
2r CH(CH3)2
2s
1
CH3
H
H
OCH3
H
57.3
aConcentration of drug inhibiting IL-1 generation by 50% of control
value. IC50 values were calculated by least-squares method.
bThe edema volume of foot pads of rats with developing AIA. The
edema of both hind paws was calculated as percentages with respect to
the control value.
cThe activity rank of AIA was defined as follows. When AIA was 0–
10, 10–25, 25–40, 40–55, 55–70, 70–85, and more than 85%, the
activity rank was classified into 0, 1, 2, 3, 4, 5 and 6, respectively.
6d
6h
9f
9c
202.4
aSee footnotes in Table 1.
bSee footnotes in Table 1.
cSee footnotes in Table 1.

4734
T. Noguchi et al. / Bioorg. Med. Chem. 11 (2003) 4729–4742
Table 3. Activities of type 2, 5, 7, and 8 toward IL-1 antagonistic
effect and AIA
Experimental
Chemistry
Melting points were determined by a Buchi 535 melting
point apparatus and are uncorrected. IR spectra were
obtained on a Perkin-Elmer 1760 spectrometer. 1H
NMR spectra were recorded on a Varian VXL-200
spectrometer. Chemical shifts are reported in ppm (d)
values, as determined using a JEOL JMS-SIX102 spec-
trometer. Elemental analyses were performed on a Per-
kin-Elmer 2400. TLC was performed on silica gel pre-
coated plates (Merck, Kieselgel 60F254). Column chro-
matography was performed over silica gel (Wako,
Wako gel C-200). 2-Acetylthiomethyl-(4-methylphenyl)-
4-oxobutanoic acid (1), 2-acetylthiomethyl-4-phenyl-4-
oxobutanoic acid (10a), 2-acetylthiomethyl-(4-chloro-
phenyl)-4-oxobutanoic acid (10b), 2-acetylthiomethyl-
(4-bromophenyl)-4-oxobutanoic acid (10c), 2-acetyl-
thiomethyl-(4-ethylphenyl)-4-oxobutanoic acid (10d) 2-
acetylthiomethyl - (4 - isopropylphenyl) - 4 - oxobutanoic
acid (10e), 2-acetylthiomethyl-(4-methoxyphenyl)-4-
oxobutanoic acid (10f), and 2-acetylthiomethyl-(4-
cyclohexylphenyl)-4-oxobutanoic acid (10g) were syn-
thesized as described in the literature.2
No.
X
R
IL-1
AIA
IC50 (mM)a % suppressionb Activity rankc
2d
7a
7b
2a
2b
7e
7h
2o
2f
H
H
H
CH3
CH3
CH3
CH3
H
CH3
H
CH3
H
51.5
45.1
—
81.1
21.7
13.5
—
50.4
34.7
29.7
—
—
1
2
1
2
1
0
3
3
5
1
4
6
3
5
3
3
4
5
6
6
3
5
14.3
35.9
23.7
34.9
17.1
ꢀ1.6
50.5
47.8
74.0
13.9
56.6
89.0
45.2
75.7
52.7
48.7
62.6
76.9
99.7
98.0
49.8
80.8
CH3 CH2CH3
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Br
Br
Br
Br
Br
Br
Br
Br
H
CH3
H
CH3
H
CH3
H
CH3
H
CH3
H
CH3
H
CH3
H
CH3
7c
7f
5c
5h
8a
8c
2p
2h
7d
7g
5d
5i
21.0
25.9
14.4
26.1
73.0
63.0
16.5
38.1
29.0
21.8
26.1
19.0
General procedure for preparation of methyl 5-(4-me-
thylphenyl)thiophene-3-carboxylate (2b–m)
To a solution of 1, 10a–g (17.4 mmol) in methanol (20
mL) was slowly added a solution of concd H2SO4 (1.5
mL) in methanol (2.0 mL). The mixture was stirred
under reflux for 5 h, and then methanol was removed
under reduced pressure. The residue was dissolved in
ethyl acetate, washed successively with satd NaHCO3,
water, and brine, and dried over anhydrous MgSO4.
The ethyl acetate solution was concentrated under
reduced pressure to give a residue, which was recrys-
tallized from solvents or purified by silica gel column
chromatography to give dihydrothiophene (11a–l).
8b
8d
aSee footnotes in Table 1.
bSee footnotes in Table 1.
cSee footnotes in Table 1.
synthesized. The antagonistic effects of these com-
pounds toward IL-1 and their suppressive effects against
AIA were evaluated and compared with those of 1.
Regarding, the substituent on the phenyl ring at the
para position (X) and the carboxylic acid (R), a SAR
study indicated that a halogen (X=Cl or Br) and free
carboxylic acid or methyl ester (R=H or CH3) sub-
stituents, respectively, are important for these activities
and that R=CH2CH3, CH2Ph or CH(CH3)2 appears to
reduce these activities. Placement of carboxylic acid at
the 2- or 3-position of the thiophene ring does not
appear to affect these activities. However, the distance
between the thiophene ring and carboxylic acid (number
of methylenes=n) greatly affects the activities: the
activities increase in the order n=1, 0, 2. Furthermore
3-(5-phenylthiophene)acrylic acid derivatives, in which
the methylene chain was ramified, were judged invalid.
Hence, the SAR indicated that [5-(4-bromophenyl)-
thiophen-3-yl]acetic acid (5d), methyl [5-(4-chloro-
phenyl)-thiophen-3-yl]acetate (5h), and methyl [5-(4-
bromophenyl)-thiophen-3-yl]acetate (5i) were more
potent toward AIA than 1 and all of the other synthe-
sized compounds.
To a solution of 11a–l (11.7 mmol) in benzene (10 mL)
was added 2,3-dichloro-5,6-dicyano-1,4-benzoquinone
(DDQ) (2.92 g, 12.9 mmol), and the mixture was stirred
at room temperature for 1.5 h. The precipitate was fil-
tered and washed with benzene. The filtrate and wash-
ings were combined and washed successively with satd
NaHCO3, water, and brine, and dried over anhydrous
MgSO4. The benzene solution was evaporated under
reduced pressure to give a residue, which was recrys-
tallized from solvents or purified by silica gel column
chromatography to give 2b–m. However, three com-
pounds 2j–l were made for next steps without identifi-
cation of the structures.
Methyl 5-(4-methylphenyl)thiophene-3-carboxylate (2b).
Compound 2b was prepared from 1 and methanol, and
recrystallized from diethylether–hexane as colorless
needles. Yield, 64% from 1;mp: 80–82 ꢁC, H NMR
1
(CDCl3) (200 MHz) d 2.37 (s, 3H), 3.89 (s, 3H), 7.20 (d,
2H, J=8 Hz), 7.50 (d, 2H, J=8 Hz), 7.68 (d, 1H, J=1
Hz), 7.99 (d, 2H, J=1 Hz). IR (KBr) cmꢀ1: 1702. MS
m/z 232 (M+). Anal. calcd for C13H12O2S: C, 67.22;H,
5.21. Found: C, 67.21;H, 5.17.

T. Noguchi et al. / Bioorg. Med. Chem. 11 (2003) 4729–4742
4735
Ethyl 5-(4-methylphenyl)thiophene-3-carboxylate (2c).
Compound 2c was prepared from 1 and ethanol, and
recrystallized from ethyl acetate–hexane as a white
recrystallized from diethylether–hexane as colorless
needles. Yield, 83% from 10c;mp: 77–79 ꢁC, H NMR
1
(CDCl3) (200 MHz) d: 1.40 (t, 3H, J=7 Hz), 4.44 (q,
2H, J=7 Hz), 7.43–7.57 (m, 4H), 7.70 (d, 1H, J=1 Hz),
8.05 (d, 1H, J=1 Hz). IR (KBr) cmꢀ1: 1718, 1708. MS
m/z 311 (M+). Anal. calcd for C13H11BrO2S: C, 50.17;
H, 3.56. Found: C, 50.33;H, 3.43.
powder. Yield, 63% from 1;mp: 35–37 ꢁC, H NMR
1
(CDCl3) (200 MHz) d: 1.40 (t, 3H, J=7 Hz), 2.39 (s,
3H), 4.35 (q, 2H, J=7 Hz), 7.20 (d, 2H, J=8 Hz), 7.51
(d, 2H, J=8 Hz), 7.66 (d, 1H, J=1 Hz), 8.00 (d, 1H,
J=1 Hz). IR (KBr) cmꢀ1: 1708. MS m/z 246 (M+).
Anal. calcd for C14H14O2S: C, 68.26;H, 5.73. Found: C,
68.30;H, 5.74.
Methyl 5-(4-ethylphenyl)thiophene-3-carboxylate (2j).
Compound 2j was prepared from 10d and methanol,
and recrystallized from diethylether–hexane as colorless
ꢁ
Methyl 5-phenylthiophene-3-carboxylate (2d). Com-
pound 2d was prepared from 10a and methanol, and
recrystallized from ethyl acetate–hexane as colorless
needles. Yield, 80% from 10d;mp: 63–67 C.
Methyl 5-(4-isopropylphenyl)thiophene-3-carboxylate (2k).
Compound 2k was prepared from 10e and methanol,
and recrystallized from diethylether–hexaꢁne as a white
powder. Yield, 82% from 10e;mp: 33–34 C.
needles. Yield, 83% from 10a;mp: 91–92 ꢁC, H NMR
1
(CDCl3) (200 MHz) d: 3.89 (s, 3H), 7.27–7.45 (m, 3H),
7.61 (m, 2H), 7.72 (d, 1H, J=1 Hz), 8.02 (1H, d, J=1
Hz). IR (KBr) cmꢀ1: 1710. MS m/z 218 (M+). Anal.
calcd for C12H10O2S: C, 66.03;H, 4.62. Found: C,
65.98;H, 4.79.
Methyl 5-(4-methoxyphenyl)thiophene-3-carboxylate (2l).
Compound 2l was prepared from 10f and methanol,
and recrystallized from diethylether–hexane as a white
powder. Yield, 78% from 10f;mp: 100–101 ꢁC.
Ethyl 5-phenylthiophene-3-carboxylate (2e). Compound
2e was prepared from 10a and ethanol, and purified by
silica gel chromatography as a pale yellow oil. Yield
from 10a, 83%; 1H NMR (CDCl3) (200 MHz) d: 1.40 (t,
3H, J=7 Hz), 4.35 (q, 2H, J=7 Hz), 7.30–7.45 (m, 3H),
7.61 (d, 2H, J=8 Hz), 7.71 (d, 1H, J=1 Hz), 8.02 (d,
1H, J=1 Hz). IR (neat) cmꢀ1: 1718. MS m/z 232 (M+).
Anal. calcd for C13H12O2S: C, 67.21;H, 5.21. Found: C,
67.07;H, 5.10.
Methyl 5-(4-cyclohexylphenyl)thiophene-3-carboxylate
(2m). Compound 2m was prepared from 10g and
methanol, and recrystallized from diethylether–hexane
ꢁ
as a white powder. Yield, 81% from 10g;mp: 94–95 C,
1H NMR (CDCl3) (200 MHz) d: 1.20–1.60 (m, 5H),
1.70–2.00 (m, 5H), 2.45–2.65 (m, 1H), 3.89 (s, 1H), 7.24
(d, 2H, J=8 Hz), 7.53 (d, 2H, J=8 Hz), 7.67 (d, 1H,
J=1 Hz), 8.00 (d, 1H, J=1 Hz). IR (KBr) cmꢀ1: 1717.
MS m/z 300 (M+). Anal. calcd for C18H20O2S: C, 71.97;
H, 6.71. Found: C, 71.80;H, 6.75.
Methyl 5-(4-chlorophenyl)thiophene-3-carboxylate (2f).
Compound 2f was prepared from 10b and methanol,
and recrystallized from diethylether–hexane as pale yel-
low needles. Yield, 74% from 10b;mp: 68–70 ꢁC, H
1
General procedure for preparation of 2a,n–t
NMR (CDCl3) (200 MHz) d: 3.87 (s, 3H), 7.35 (d, 2H,
J=8 Hz), 7.52 (d, 2H, J=8 Hz), 7.68 (d, 1H, J=1 Hz),
8.03 (d, 1H, J=1 Hz). IR (KBr) cmꢀ1: 1707. MS m/z
252 (M+). Anal. calcd for C12H9ClO2S: C, 57.02;H,
3.59. Found: C, 56.93;H, 3.44.
To a solution of 2b–m (11.1 mmol) in tetrahydrofuran
(THF) (10 mL) was added a solution of KOH (2.50 g,
37.9 mmol) in methanol (5.0 mL) and water (1.0 mL).
The mixture was stirred at room temperature for 4 h.
The resulting solution was acidified with 10% HCl, and
then concentrated under reduced pressure. The residue
was dissolved in ethyl acetate, washed successively with
sat. NaHCO3, water, and brine, and dried over anhy-
drous MgSO4. The ethyl acetate solution was evapo-
rated under reduced pressure to give a residue, which
was recrystallized from solvents to give 2a,n–t.
Ethyl 5-(4-chlorophenyl)thiophene-3-carboxylate (2g).
Compound 2g was prepared from 10b and ethanol, and
recrystallized from diethylether–hexane as pale yellow
needles. Yield, 71% from 10b;mp: 69–70 ꢁC, H NMR
1
(CDCl3) (200 MHz) d: 1.39 (t, 3H, J=7 Hz), 4.35 (q,
2H, J=7 Hz), 7.36 (d, 2H, J=8 Hz), 7.55 (d, 2H, J=8
Hz), 7.69 (d, 1H, J=1 Hz), 8.02 (d, 1H, J=1 Hz). IR
(KBr) cmꢀ1: 1708. MS m/z 266 (M+). Anal. calcd for
C13H11ClO2S: C, 58.54;H, 4.16. Found: C, 58.64;H,
4.07.
5-(4-Methylphenyl)thiophene-3-carboxylic acid (2a).
Compound 2a was prepared from 2b, and recrystallized
from toluene as colorless prisms. Yield, 87%;mp: 192–
ꢁ
1
193 C, H NMR (CDCl3) (200 MHz) d: 2.38 (s, 3H),
7.22 (d, 2H, J=8 Hz), 7.51 (d, 2H, J=8 Hz), 7.70 (d,
Methyl 5-(4-bromophenyl)thiophene-3-carboxylate (2h).
Compound 2h was prepared from 10c and methanol,
and recrystallized from diethylether–hexane as a white
1H, J=1 Hz), 8.13 (d, 1H, J=1 Hz). IR (KBr) cmꢀ1
:
2599, 1671. MS m/z 218 (M+). Anal. calcd for
C12H10O2S: C, 66.03;H, 4.62. Found: C, 66.09;H, 4.53.
powder. Yield, 88% from 10c;mp: 90–93 ꢁC, H NMR
1
(CDCl3) (200 MHz) d: 3.89 (s, 3H), 7.43–7.57 (m, 4H),
7.70 (d, 1H, J=1 Hz), 8.03 (d, 1H, J=1 Hz). IR (KBr)
cmꢀ1: 1718. MS m/z 297 (M+). Anal. calcd for
C12H9BrO2S: C, 48.50;H, 3.05. Found: C, 48.52;H, 2.96.
5-Phenylthiophene-3-carboxylic acid (2n). Compound 2n
was prepared from 2d, and recrystallized from ethyl
acetate–hexane as colorless crystals. Yield, 89%;mp:
180–181 ꢁC, H NMR (CDCl3) (200 MHz) d: 7.39–7.48
1
Ethyl 5-(4-bromophenyl)thiophene-3-carboxylate (2i).
Compound 2i was prepared from 10c and ethanol, and
(m, 3H), 7.62 (d, 2H, J=9 Hz), 7.77 (d, 1H, J=1 Hz),
8.18 (d, 1H, J=1 Hz). IR (KBr) cmꢀ1: 1671. MS m/z

4736
T. Noguchi et al. / Bioorg. Med. Chem. 11 (2003) 4729–4742
204 (M+). Anal. calcd for C11H8O2S: C, 64.68;H, 3.95.
Found: C, 64.42;H, 3.81.
(32.5 mmol) and K2CO3 (2.70 g, 19.5 mmol) at room
temperature. The mixture was stirred at 60 ꢁC for 4 h.
Water (30 mL) was added to the resulting solution,
which was then extracted with ethyl acetate. The extract
was washed successively with water and brine, and dried
over anhydrous MgSO4. The ethyl acetate solution was
concentrated under reduced pressure to give a residue,
which was recrystallized from solvents to give 2u,v.
5-(4-Chlorophenyl)thiophene-3-carboxylic acid (2o).
Compound 2o was prepared from 2f, and recrystallized
from ethyl acetate–hexane as colorless crystals. Yield,
86%;mp: 204–206 ꢁC, H NMR (CDCl3) (200 MHz) d:
1
7.40 (d, 2H, J=8 Hz), 7.55 (d, 2H, J=8 Hz), 7.73 (d, 1H,
J=1 Hz), 8.18 (d, 1H, J=1 Hz). IR (KBr) cmꢀ1: 3112,
2597, 1671. MS m/z 238 (M+). Anal. calcd for C11H7
ClO2S: C, 55.35;H, 2.96. Found: C, 55.49;H, 2.89.
Isopropyl 5-(4-bromophenyl)thiophene-3-carboxylate (2u).
Compound 2u was prepared from isopropylbromide,
and recrystallized from hexane as colorless needles. Yield,
ꢁ
5-(4-Bromophenyl)thiophene-3-carboxylic acid (2p).
Compound 2p was prepared from 2h, and recrystallized
from ethꢁyl acetate as colorless prisms. Yield, 84%;mp:
77%;mp: 77–79 C, 1H NMR (CDCl3) (200 MHz) d: 1.37
(d, 6H, J=6 Hz), 5.21 (septet, 1H, J=6 Hz), 7.45–7.57
(m, 4H), 7.70 (d, 1H, J=1 Hz), 8.02 (d, 1H, J=1 Hz). IR
(KBr) cmꢀ1: 1715. MS m/z 325 (M+). Anal. calcd for
C14H13BrO2S: C, 57.92;H, 3.51. Found: C, 57.92;H, 3.38.
1
212–213 C, H NMR (CDCl3) (200 MHz) d: 7.48 (d,
2H, J=9 Hz), 7.52 (d, 2H, J=9 Hz), 7.73 (d, 1H, J=1
Hz), 8.18 (d, 1H, J=1 Hz). IR (KBr) cmꢀ1: 1671, 1538.
MS m/z 283 (M+). Anal. calcd for C11H7BrO2S: C,
46.66;H, 2.49. Found: C, 46.83;H, 2.40.
Benzyl 5-(4-bromophenyl)thiophene-3-carboxylate (2v).
Compound 2v was prepared from benzylbromide, and
recrystallized from diethylether–hexane as colorless
needles. Yield, 77%;mp: 63–66 ꢁC, H NMR (CDCl3)
1
5-(4-Ethylphenyl)thiophene-3-carboxylic acid (2q). Com-
pound 2q was prepared from 2j, and recrystallized from
ethyl acetate as colorless crystals. Yield, 63%;mp: 196–
197 ꢁC, 1H NMR (CDCl3) (200 MHz) d: 1.27 (t, 3H, J=7
Hz), 2.68 (q, 2H, J=7 Hz), 7.24 (d, 2H, J=9 Hz), 7.55 (d,
2H, J=9 Hz), 7.72 (d, 1H, J=1 Hz), 8.14 (d, 1H, J=1 Hz).
IR (KBr) cmꢀ1: 2967, 1673. MS m/z 232 (M+). Anal. calcd
for C13H12O2S: C, 67.22;H, 5.21. Found: C, 67.21;H, 5.17.
(200 MHz) d: 5.33 (m, 2H), 7.34–7.55 (m, 9H), 7.71 (d,
1H, J=1 Hz), 8.08 (d, 1H, J=1 Hz). IR (KBr) cmꢀ1
:
1714. MS m/z 373 (M+). Anal. calcd for C18H13BrO2S:
C, 57.92;H, 3.51. Found: C, 57.92;H, 3.38.
General procedure for preparation of 5a–e
To a solution of sodium metal (4.6 g, 200 mmol) in
ethanol (100 mL) was added ethyl thioglycolate (21.6 g,
180 mmol) under ice cooling, and the mixture was
allowed to stand at room temperature for 20 min. Ethyl
cinnamate (22) (31.7 g, 180 mmol) was then added. The
reaction mixture was stirred at room temperature for 2
h. The ethanol solution was concentrated under reduced
pressure to give a residue, which was refluxed with 1.5
mol/L H2SO4 (100 mL) for 3 h. The resulting solution
was extracted with diethylether, washed successively
with water, satd NaHCO3, and brine, and dried over
anhydrous MgSO4. The diethylether solution was evap-
orated under reduced pressure to give a residue, which
was purified by silica gel column chromatography to
afford ethyl 5-phenylthiolane-3-on-2-carboxylate (23)
(29.3 g, 65%). To a solution of 4.5 mol/L H2SO4 (80
mL) and acetic acid (200 mL) was added 23 (29.3 g, 117
mmol), and the mixture was stirred under reflux for 1 h.
Acetic acid was removed under reduced pressure, and
the mixture was extracted with diethylether. The extract
was washed successively with water and brine and dried
over anhydrous MgSO4 to give a residue, which was
purified by silica gel column chromatography to give 5-
phenylthiolane-3-on (24) (17.9 g, 86%) as pale yellow
crystals. To a solution of 24 (2.33 g, 13.1 mmol) and
cyanoacetic acid (2.00 g, 23.5 mmol) in benzene (50 mL)
was added acetic acid (1.0 mL) and piperidine (1.0 mL),
and the mixture was stirred under reflux for 6 h. The
resulting solution was washed successively with water,
5% HCl, satd NaHCO3, and brine, and dried over
anhydrous MgSO4. The benzene solution was evapo-
rated under reduced pressure to give a residue, which
was dissolved in toluene (30 mL), and then DDQ (3.20
g, 14.1 mmol) was added. The mixture was stirred under
5-(4-Isopropylphenyl)thiophene-3-carboxylic acid (2r).
Compound 2r was prepared from 2k, and recrystallized
from ethyl acetate as colorless crystals. Yield, 75%;mp:
204–205 ꢁC, H NMR (CDCl3) (200 MHz) d: 1.27 (d,
1
6H, J=6 Hz), 2.94 (septet, 1H, J=6 Hz), 7.27 (d, 2H,
J=8 Hz), 7.55 (d, 2H, J=8 Hz), 7.70 (d, 1H, J=1 Hz),
8.13 (d, 1H, J=1 Hz). IR (KBr) cmꢀ1: 2963, 1675. MS
m/z 246 (M+). Anal. calcd for C14H14O2S: C, 68.26;H,
5.73. Found: C, 68.35;H, 5.81.
5-(4-Methoxyphenyl)thiophene-3-carboxylic acid (2s).
Compound 2s was prepared from 2l, and recrystallized
from ethyl acetate–hexane as a white powder. Yield,
44%;mp: 197 ꢁC, H NMR (CDCl3) (200 MHz) d: 3.85
1
(s, 3H), 6.93 (d, 2H, J=8 Hz), 7.55 (d, 2H, J=8 Hz),
7.63 (d, 1H, J=1 Hz), 8.09 (d, 1H, J=1 Hz). IR (KBr)
cmꢀ1: 3106, 1668. MS m/z 234 (M+). Anal. calcd for
C12H10O3S: C, 61.52;H, 4.30. Found: C, 61.39;H, 4.22.
5-(4-Cyclohexylphenyl)thiophene-3-carboxylic acid (2t).
Compound 2t was prepared from 2m, and recrys-
tallized from ethyl acetate as colorless crystals. Yield,
65%;mp: >300 ꢁC, H NMR (CDCl3) (200 MHz) d:
1
1.33–1.55 (m, 5H), 1.70–2.00 (m, 5H), 2.45–2.60 (m,
1H), 7.24 (d, 2H, J=8 Hz), 7.53 (d, 2H, J=8 Hz), 7.70
(d, 1H, J=1 Hz), 8.12 (d, 1H, J=1 Hz). IR (KBr) cmꢀ1
:
2927, 1668. MS m/z 286 (M+). Anal. calcd for
C17H18O2S: C, 71.29;H, 6.33. Found: C, 71.28;H, 6.29.
General procedure for preparation of 2u,v
To a solution of 2p (2.83 g, 10.0 mmol) in DMF (30
mL) was added benzylbromide or isopropylbromide

T. Noguchi et al. / Bioorg. Med. Chem. 11 (2003) 4729–4742
4737
reflux for 1 h, and the precipitate was filtered and
ethyl acetate as pale yellow crystals. Yield, 76%;mp:
149 ꢁC, H NMR (CDCl3) (200 MHz) d: 2.35 (s, 3H),
3.67 (s, 2H), 7.06 (d, 1H, J=2 Hz), 7.15 (d, 2H, J=9
Hz), 7.19 (d, 1H, J=2 Hz), 7.45 (d, 2H, J=9 Hz). IR
(KBr) cmꢀ1: 2917, 1698. MS m/z 232 (M+). Anal. calcd
for C13H12O2S: C, 67.22;H, 5.21. Found: C, 67.32;H,
5.19.
1
washed with toluene. The filtrate and washings were
combined and washed successively with satd NaHCO3,
water, and brine, and dried over anhydrous MgSO4.
The toluene solution was concentrated under reduced
pressure to give a residue, which was purified by silica
gel column chromatography and then recrystallized
from diethylether–hexane to give (5-phenylthiophen-3-
yl)acetonitrile (25a) (1.65 g, 63%) as colorless crystals.
[5-(4-Chlorophenyl)thiophen-3-yl]acetic acid (5c). Com-
pound 5c was prepared from 2f, and recrystallized from
ethyl acetate as colorless crystals. Yield, 92%;mp:
To a suspended solution of LiAlH4 (4.00 g, 105 mmol)
and diethylether (200 mL) was slowly added 2b,f,h,l
(103 mmol), and the mixture was stirred under reflux for
0.5 h. The reaction mixture was quenched with 1% HCl
(20 mL), and extracted with ethyl acetate. The extract
was washed successively with water and brine, and dried
over anhydrous MgSO4. The ethyl acetate solution was
evaporated under reduced pressure to give a residue,
which was dissolved in THF (200 mL) and hexamethyl-
phosphoric triamide (HMPA) (40 mL), and thionyl
chloride (15.0 mL, 206 mmol) was added. The reaction
mixture was stirred at room temperature for 0.5 h, and
then evaporated under reduced pressure to give a resi-
due. To the residue was added water (300 mL), and the
mixture was extracted with diethylether. The extract
was washed successively with water and brine, and dried
over anhydrous MgSO4. The diethylether solution was
evaporated under reduced pressure to give crude chlo-
ride (26a–d), which was dissolved in acetonitrile (200
mL). Potassium cyanide (8.00 g, 123 mmol) and 18-
crown-6 (2.00 g, 7.57 mmol) was added, and the solu-
tion was stirred overnight at room temperature. The
reaction mixture was poured into water (200 mL) and
extracted with ethyl acetate. The extract was washed
successively with water and brine, and dried over anhy-
drous MgSO4. The ethyl acetate solution was evapo-
rated under reduced pressure to give a residue, which
was purified by silica gel column chromatography, and
then recrystallized from diethylether- hexane to give
acetonitrile derivatives (25b–e) (65–80%).
151 ꢁC, H NMR (CDCl3) (200 MHz) d: 3.69 (s, 2H),
1
7.11 (d, 1H, J=2 Hz), 7.23 (d, 2H, J=2 Hz), 7.33 (d,
2H, J=9 Hz), 7.50 (d, 2H, J=9 Hz). IR (KBr) cmꢀ1
:
3091, 1698. MS m/z 252 (M+). Anal. calcd for
C12H9ClO2S: C, 57.02;H, 3.59. Found: C, 57.00;H,
3.44.
[5-(4-Bromophenyl)thiophen-3-yl]acetic acid (5d). Com-
pound 5d was prepared from 2h, and recrystallized from
ethyl acetate as colorless crystals. Yield, 94%;mp:
164 ꢁC, H NMR (CDCl3) (200 MHz) d: 3.69 (s, 2H),
1
7.11 (d, 1H, J=2 Hz), 7.23 (d, 2H, J=1 Hz), 7.43 (d,
2H, J=8 Hz), 7.50 (d, 2H, J=8 Hz). IR (KBr) cmꢀ1
:
3090, 1698. MS m/z 252 (M+). Anal. calcd for
C12H9BrO2S: C, 48.50;H, 3.05. Found: C, 48.49;H,
2.94.
[5-(4-Methoxyphenyl)thiophen-3-yl]acetic
Compound 5e was prepared from 2l, and recrystallized
acid
(5e).
from ethyl acetate as colorless crystals. Yield, 90%;mp:
149 ꢁC, H NMR (CDCl3) (200 MHz) d: 3.57 (s, 2H),
1
3.78 (s, 3H), 6.97 (d, 2H, J=9 Hz), 7.20 (s, 1H), 7.25 (s,
1H), 7.54 (d, 2H, J=9 Hz). IR (KBr) cmꢀ1: 3090, 1698.
MS m/z 248 (M+). Anal. calcd for C13H12O3S: C, 62.88;
H, 4.87. Found: C, 62.95;H, 4.80.
General procedure for preparation of 5f–i
To a solution of conc H2SO4 (3 mL) in methanol (30
mL) was added 5a–e (27.5 mmol), the mixture was stir-
red under reflux for 2 h, and then methanol was
removed under reduced pressure. The residue was dis-
solved in ethyl acetate, washed successively with sat.
NaHCO3, water, and brine, and dried over anhydrous
MgSO4. The ethyl acetate solution was concentrated
under reduced pressure to give a residue, which was
purified by silica gel column chromatography or recrys-
tallized from solvents to give 5f–i.
To a solution of 25a–e (49.1 mmol) in ethanol (30 mL)
was added KOH (25.0 g, 379 mmol) in water (50 mL) at
room temperature with stirring. The reaction mixture
was refluxed for 1 h. The reaction mixture was poured
into 10% HCl (200 mL) and extracted with ethyl ace-
tate. The extract was washed successively with water
and brine, and dried over anhydrous MgSO4. The ethyl
acetate solution was evaporated under reduced pressure
to give a residue, which was recrystallized from ethyl
acetate to give 5a–e.
Methyl (5-phenylthiophen-3-yl)acetate (5f). Compound
5f was prepared from 5a, and purified by silica gel col-
umn chromatography as a pale yellow oil. Yield, 99%;
1H NMR (CDCl3) (200 MHz) d: 3.64 (s, 2H), 3.72 (s,
3H), 7.07 (m, 1H), 7.13–7.40 (m, 4H), 7.58 (d, 2H, J=9
Hz). IR (KBr) cmꢀ1: 3060, 1737. MS m/z 232 (M+).
Anal. calcd for C12H12O2S: C, 67.22;H, 5.21. Found: C,
66.98;H, 5.12.
(5-Phenylthiophen-3-yl)acetic acid (5a). Compound 5a
was prepared from 22, and recrystallized from ethyl
acetate as pale yellow crystals. Yield, 95%;mp: 154–
155 ꢁC, H NMR (CDCl3) (200 MHz) d: 3.70 (s, 2H),
1
7.11 (m, 1H), 7.15–7.45 (m, 4H), 7.59 (d, 2H, J=9 Hz).
IR (KBr) cmꢀ1: 3094, 1698. MS m/z 218 (M+). Anal.
calcd for C12H10O2S: C, 66.03;H, 4.62. Found: C,
66.07;H, 4.52.
Methyl [5-(4-methylphenyl)thiophen-3-yl]acetate (5g).
Compound 5g was prepared from 5b, and purified by
silica gel column chromatography as a pale yellow oil.
[5-(4-Methylphenyl)thiophen-3-yl]acetic acid (5b). Com-
pound 5b was prepared from 2b, and recrystallized from
1
Yield, 92%; H NMR (CDCl3) (200 MHz) d: 2.36 (s,

4738
T. Noguchi et al. / Bioorg. Med. Chem. 11 (2003) 4729–4742
3H), 3.64 (s, 2H), 3.73 (s, 3H), 7.04 (m, 1H), 7.17 (m,
3H), 7.48 (d, 2H, J=9 Hz). IR (KBr) cmꢀ1: 2951, 1741.
MS m/z 246 (M+). Anal. calcd for C14H14O2S: C, 68.26;
H, 5.73. Found: C, 68.06;H, 5.61.
3-(5-Phenylthiophen-3-yl)propionic acid (6a). Compound
6a was prepared from 26e, and recrystallized from ethyl
ꢁ
acetate as colorless crystals. Yield, 62%;mp: 134 C, 1H
NMR (CDCl3) (200 MHz) d: 2.71 (t, 2H, J=8 Hz), 2.97
(t, 2H, J=8 Hz), 6.94 (d, 1H, J=2 Hz), 7.17 (d, 1H,
J=2 Hz), 7.22–7.44 (m, 3H), 7.58 (d, 2H, J=8 Hz). IR
(KBr) cmꢀ1: 2913, 1685. MS m/z 232 (M+). Anal. calcd
for C13H12O2S: C, 67.22;H, 5.21. Found: C, 67.23;H,
5.21.
Methyl [5-(4-chlorophenyl)thiophen-3-yl]acetate (5h).
Compound 5h was prepared from 5c, and recrystallized
from diethylether–hexane as pale yellow crystals. Yield,
91%;mp: 38 ꢁC, H NMR (CDCl3) (200 MHz) d: 3.65
1
(s, 2H), 3.73 (s, 3H), 7.09 (m, 1H), 7.22 (d, 1H, J=2
Hz), 7.32 (d, 2H, J=9 Hz), 7.50 (d, 2H, J=2 Hz). IR
(KBr) cmꢀ1: 3094, 1747. MS m/z 266 (M+). Anal. calcd
for C13H11ClO2S: C, 58.54;H, 4.16. Found: C, 58.49;H,
4.04.
3-[5-(4-Methylphenyl)thiophen-3-yl]propionic acid (6b).
Compound 6b was prepared from 26a, and recrys-
tallized from ethyl acetate–hexane as colorless crystals.
Yield, 77%;mp: 122 ꢁC, H NMR (CDCl3) (200 MHz)
1
d: 2.35 (s, 3H), 2.73 (t, 2H, J=8 Hz), 2.95 (t, 2H, J=8
Hz), 6.90 (d, 1H, J=1 Hz), 7.13 (d, 1H, J=1 Hz), 7.15
Methyl [5-(4-bromophenyl)thiophen-3-yl]acetate (5i).
Compound 5i was prepared from 5d, and recrystallized
from diethylether-hexane as pale yellow crystals. Yield,
91%;mp: 59 C, H NMR (CDCl3) (200 MHz) d: 3.64
(s, 2H), 3.72 (s, 3H), 7.10 (m, 1H), 7.24 (d, 1H, J=2
Hz), 7.43 (d, 2H, J=8 Hz), 7.48 (d, 2H, J=8 Hz). IR
(KBr) cmꢀ1: 3095, 1746. MS m/z 311 (M+). Anal. calcd
for C12H9BrO2S: C, 50.18;H, 3.56. Found: C, 50.11;H,
3.43.
(d, 2H, J=8 Hz), 7.48 (d, 2H, J=8 Hz). IR (KBr) cmꢀ1
:
3436, 2913, 1693, 1219. MS m/z 246 (M+). Anal. calcd
for C14H14O2S: C, 68.26;H, 5.73. Found: C, 68.53;H,
5.70.
ꢁ
1
3-[5-(4-Chlorophenyl)thiophen-3-yl]propionic acid (6c).
Compound 6c was prepared from 26b, and recrys-
tallized from ethyl acetate–hexane as colorless crystals.
Yield, 64%;mp: 128 ꢁC, H NMR (CDCl3) (200 MHz)
1
d: 2.73 (t, 2H, J=8 Hz), 2.98 (t, 2H, J=8 Hz), 6.95 (d,
1H, J=1 Hz), 7.15 (d, 1H, J=1 Hz), 7.33 (d, 2H, J=8
Hz), 7.50 (d, 2H, J=8 Hz). IR (KBr) cmꢀ1: 3436, 2932,
1703, 1217. MS m/z 266 (M+). Anal. calcd for
C13H11ClO2S: C, 58.54;H, 4.16. Found: C, 58.55;H,
4.04.
General procedure for preparation of 6a–d
Compounds 26e were prepared from 2d in a manner
analogous to that used for the preparation of 26a–d. To
a solution of sodium metal (2.80 g, 122 mmol) in etha-
nol (350 mL) was added diethyl malonate (27.7 mL, 182
mmol) at room temperature. After the mixed solution
was heated under gentle reflux with stirring, 26b–e (122
mmol) was added. The whole mixture was refluxed for
1.5 h, and then ethanol was removed under reduced
pressure. To the concentrate was added water (100 mL),
and the mixture was extracted with ethyl acetate. The
extract was washed successively with water and brine,
and dried over anhydrous MgSO4. The ethyl acetate
solution was evaporated under reduced pressure to give
a residue, which was purified by silica gel column chro-
matography to give diester (28a–d) (60–65%). To a
solution of 28a–d (72.9 mmol) in DMSO (150 mL) was
added a solution of NaCl (8.80 g, 151 mmol) in water
(4.8 mL) at room temperature, and the mixture was
stirred under reflux for 5 h. The resulting solution was
poured into water (200 mL), and extracted with ethyl
acetate. The extract was washed successively with water
and brine, and dried over anhydrous MgSO4. The ethyl
acetate solution was evaporated under reduced pressure
to give ethyl ester (29a–d) (71–88%).
3-[5-(4-Bromophenyl)thiophen-3-yl]propionic acid (6d).
Compound 6d was prepared from 26c, and recrys-
tallized from ethyl acꢁetate–hexane as colorless crystals.
1
Yield, 81%;mp: 129 C, H NMR (CDCl3) (200 MHz)
d: 2.73 (t, 2H, J=8 Hz), 2.98 (t, 2H, J=8 Hz), 6.95 (d,
1H, J=1 Hz), 7.15 (d, 1H, J=1 Hz), 7.30–7.60 (m, 4H).
IR (KBr) cmꢀ1: 2916, 1697, 1221. MS m/z 311 (M+).
Anal. calcd for C13H11BrO2S: C, 50.18;H, 3.56. Found:
C, 50.17;H, 3.51.
General procedure for preparation of 6e–h. Compound
6e–h was prepared from 6a–d in a manner analogous to
that used for the preparation of 5f–i.
Methyl 3-(5-phenylthiophen-3-yl)propionate (6e). Com-
pound 6e was prepared from 6a, and recrystallized from
diethylether–hexane as colorless crystals. Yield, 94%;
mp: 67 ꢁC, H NMR (CDCl3) (200 MHz) d: 2.66 (t, 2H,
1
J=8 Hz), 2.97 (t, 2H, J=8 Hz), 3.70 (s, 3H), 6.93 (d,
1H, J=2 Hz), 7.16 (d, 1H, J=2 Hz), 7.22–7.44 (m, 3H),
7.58 (d, 2H, J=8 Hz). IR (KBr) cmꢀ1: 2949, 1733. MS
m/z 246 (M+). Anal. calcd for C14H14O2S: C, 68.26;H,
5.73. Found: C, 68.00;H, 5.72.
To a solution of 29a–d (59.0 mmol) in methanol
(400 mL) was added NaOH (14.1 g, 353 mmol) in water
(100 mL) at room temperature with stirring, and the
stirring was continued for 1 h. Methanol was removed
under reduced pressure and poured into 5% HCl
(100 mL), which was extracted with ethyl acetate. The
extract was washed successively with water and brine,
and dried over anhydrous MgSO4. The ethyl acetate
solution was evaporated under reduced pressure to give
a residue, which was recrystallized from solvents to give
6a–d.
Methyl 3-[5-(4-methylphenyl)thiophen-3-yl]propionate (6f).
Compound 6f was prepared from 6b, and recrystallized
from hexane–petroleum ether as pale yellow crystals.
ꢁ
Yield, 84%;mp: 60 C, 1H NMR (CDCl3) (200 MHz) d:
2.35 (s, 3H), 2.65 (t, 2H, J=8 Hz), 2.95 (t, 2H, J=8
Hz), 3.70 (s, 3H), 6.90 (d, 1H, J=1 Hz), 7.10 (d, 1H,
J=1 Hz), 7.18 (d, 2H, J=8 Hz), 7.48 (d, 2H, J=8 Hz).

T. Noguchi et al. / Bioorg. Med. Chem. 11 (2003) 4729–4742
4739
IR (KBr) cmꢀ1: 3461, 2913, 1742. MS m/z 260 (M+).
Anal. calcd for C15H16O2S: C, 69.20;H, 6.19. Found: C,
69.37;H, 6.14.
Methyl 5-phenylthiophene-2-carboxylate (7b). To a solu-
tion of concd H2SO4 (0.2 mL) in methanol (5 mL) was
added 5a (1.40 g, 6.85 mmol), and the mixture was stir-
red under reflux for 0.5 h. Methanol was then removed
under reduced pressure. The residue was dissolved in
ethyl acetate, washed successively with satd NaHCO3,
water, and brine, and dried over anhydrous MgSO4.
The ethyl acetate solution was concentrated under
reduced pressure to give a residue, which was purified
by silica gel column chromatography to give 7b (1.26 g,
84%) as a pale yellow oil. 1H NMR (CDCl3) (200 MHz)
d: 3.90 (s, 3H), 7.29 (d, 1H, J=4 Hz), 7.40 (m, 3H), 7.65
(dd, 2H, J=2, 8 Hz), 7.78 (d, 1H, J=4 Hz). IR (KBr)
cmꢀ1: 2980, 1706. MS m/z 218 (M+). Anal. calcd for
C12H10O2S: C, 66.03;H, 4.62. Found: C, 66.04;H, 4.56.
Methyl 3-[5-(4-chlorophenyl)thiophen-3-yl]propionate (6g).
Compound 6g was prepared from 6c, and recrystallized
from methanol as colorless crystals. Yield, 83%;mp:
85 ꢁC, 1H NMR (CDCl3) (200 MHz) d: 2.65 (t, 2H, J=8
Hz), 2.95 (t, 2H, J=8 Hz), 3.70 (s, 3H), 6.93 (d, 1H,
J=1 Hz), 7.13 (d, 1H, J=1 Hz), 7.33 (d, 2H, J=8 Hz),
7.50 (d, 2H, J=8 Hz). IR (KBr) cmꢀ1: 3448, 2950, 1739,
1171. MS m/z 280 (M+). Anal. calcd for C14H13ClO2S:
C, 59.89;H, 4.67. Found: C, 60.00;H, 4.57.
Methyl 3-[5-(4-bromophenyl)thiophen-3-yl]propionate (6h).
Compound 6h was prepared from 6d, and recrystallized
from methanol as colorless crystals. Yield, 73%;mp:
87 ꢁC, 1H NMR (CDCl3) (200 MHz) d: 2.66 (t, 2H, J=8
Hz), 2.95 (t, 2H, J=8 Hz), 3.70 (s, 3H), 6.95 (d, 1H,
J=1 Hz), 7.14 (d, 1H, J=1 Hz), 7.38–7.53 (m, 4H). IR
(KBr) cmꢀ1: 3449, 2949, 1741, 1170. MS m/z 325 (M+).
Anal. calcd for C14H13BrO2S: C, 51.70;H, 4.03. Found:
C, 51.84;H, 3.97.
General procedure for preparation of 7c–e
To a suspended solution of AlCl3 (32.3 g, 242 mmol)
and chlorobutyryl chloride (17) (31.0 g, 220 mmol) in
CS2 (50 mL) was slowly added a solution of 16a–c (199
mmol) in CS2 (50 mL) with stirring at room tempera-
ture. Stirring was continued for 2.5 h, and the resulting
solution was poured into 10% HCl (200 mL) and
extracted with ethyl acetate. The extract was washed
successively with water, sat. NaHCO3, and brine, and
dried over anhydrous MgSO4. The ethyl acetate solu-
tion was concentrated under reduced pressure to give a
residue, which was purified by silica gel column chro-
matography and then recrystallized from cyclohexane/
petroleum ether to give chloride (18a–c) (51–54%).
5-Phenylthiophene-2-carboxylic ccid (7a). A suspended
solution of rhodanine (13) (21.8 g, 163 mmol), sodium
acetate (40.3 g, 489 mmol) and cinnamaldehyde (12)
(21.5 g, 163 mmol) in acetic acid (200 mL) was refluxed
for 0.5 h, and then poured into 800 g of ice. The orange
solid was collected and recrystallized from toluene to
give 24.2 g (60%) of 5-cinnamylidenerhodanine (14).
A solution of 14 (10.0 g, 40.4 mmol) in 5% NaOH (50
mL) was stirred at 80 ꢁC for 0.5 h. The resulting solu-
tion was filtered through a charcoal pad and cooled to
0 ꢁC, and 10% chilled HCl (50 mL) was added. The pre-
cipitate of 2-mercapto-5-phenyl-2,4-pentadienoic acid
(6.02 g, 72%) was collected. The crude product was
dissolved in pyridine (50 mL) and cooled to 3 ꢁC, and
4.6 mL of 30% hydrogen peroxide was slowly added with
stirring. After standing for 5 h, the solution was poured
into 10% HCl (300 mL). The resulting solid was col-
lected, washed with water, and dried to give 2.67 g (32%)
of 2,20-dithiobis(5-phenyl-2,4-pentadienoic acid) (15).
To a solution of 18a–c (103 mmol) in DMF (50 mL) was
added a solution of potassium thioacetate (12.4 g, 109
mmol) in DMF (100 mL) at 5 ꢁC with stirring. Stirring
was continued for 22 h. The resulting solution was
poured into water (300 mL) and extracted with diethy-
lether. The extract was washed successively with 5%
HCl, satd NaHCO3, and brine, and dried over anhy-
drous MgSO4. The ethyl acetate solution was con-
centrated under reduced pressure to give a residue,
which was purified by silica gel column chromatography
and then recrystallized from diethylether–hexane to give
thioacetate (19a–c) (83–86%).
To a solution of 15 (2.50 g, 6.09 mmol) in chilled etha-
nol (30 mL) was slowly adde a solution of iodine (1.85
g, 14.6 mmol) in ethanol (5 mL) with stirring. The
solution was stirred at room temperature for 2 days,
and then poured into chilled water (200 mL) containing
sodium bisulfite (5.0 g). After the aqueous supernatant
was decanted, the residue was taken up on hot 10%
NaOH (100 mL), filtered through a heated Buchner
funnel and cooled, to give white crystals of the sodium
salt of 7a. This product was collected, and washed with
water and 5% HCl (100 mL). Upon recrystallization
from ethyl acetate–hexane, 7a was obtained as a white
powder (1.94 g, 78%). mp: 188–189 ꢁC, 1H NMR
(CDCl3) (200 MHz) d: 7.33 (d, 1H, J=1 Hz), 7.41 (m,
3H), 7.67 (m, 2H), 7.87 (d, 1H, J=4 Hz), 9.43 (br s,
1H). IR (KBr) cmꢀ1: 3059, 2869, 1704, 1661, 1540. MS
m/z 204 (M+). Anal. calcd for C11H8O2S: C, 64.69;H,
3.95. Found: C, 64.69;H, 3.80.
A solution of 19a–c (83.0 mmol) in concd H2SO4 (13
mL) and methanol (130 mL) was refluxed for 1 h, and
then methanol was removed under reduced pressure.
The residue was dissolved in ethyl acetate and washed
successively with satd NaHCO3, water, and brine, and
dried over anhydrous MgSO4. The ethyl acetate solu-
tion was concentrated under reduced pressure to give a
residue which was dissolved in benzene (170 mL), and
chloranil (20.6 g, 83.8 mmol) was then added. The mix-
ture was stirred under reflux for 2 h, and then a crys-
talline precipitate was filtered and washed with benzene.
The filtrate and washings were combined and washed
successively with 5% KOH, water, and brine, and dried
over anhydrous MgSO4. The benzene solution was eva-
porated under reduced pressure to give a residue, which
was purified by silica gel column chromatography and
then recrystallized from hexane to give phenylthiophene
(20a–c) (68–73%).

4740
T. Noguchi et al. / Bioorg. Med. Chem. 11 (2003) 4729–4742
To a solution of DMF (13 mL) and 1,2-dichloroethane
(50 mL) was slowly added a solution of POCl3 (15.7
mL, 172 mmol) in 1,2-dichloroethane (50 mL) with
stirring over 0.5 h at 0–5 ꢁC. To the reaction mixture
was slowly added a solution of 20a–c (83.6 mmol) in
1,2-dichloroethane (50 mL) over 15 min below 10 ꢁC,
and the mixture was stirred under reflux for 17 h. The
resulting solution was poured into chilled 50% KOH
(20 mL) and extracted with ethyl acetate. The extract
was washed successively with 5% HCl, water, and brine,
and dried over MgSO4. The ethyl acetate solution was
evaporated under reduced pressure to give a residue,
which was recrystallized from ethyl acetate–hexane to
give formate (21a–c) (82–85%).
resulting solution was concentrated under reduced
pressure to about 30 mL. The mixture was poured into
water and extracted with ethyl acetate. The extract was
washed successively with satd NaHCO3, water, and
brine and dried over anhydrous MgSO4. The ethyl ace-
tate solution was evaporated under reduced pressure to
give a residue, which was recrystallized from ethyl ace-
tate–hexane to give 7f–h.
Methyl 5-(4-chlorophenyl)thiophene-2-carboxylate (7f).
Compound 7f was prepared from 7c and methanol,
and recrystallized from ethyl acetate–hexane as a white
powder. Yield, 86%;mp: 113 ꢁC, 1H NMR (CDCl3)
(200 MHz) d: 3.90 (s, 3H), 7.25 (d, 1H, J=5 Hz), 7.30–
7.42 (m, 2H), 7.50–7.60 (m, 2H), 7.75 (d, 1H, J=5 Hz).
IR (KBr) cmꢀ1: 3392, 3099, 2951, 1702, 1532, 1447. MS
m/z 252 (M+). Anal. calcd for C12H9ClO2S: C, 57.04;
H, 3.59. Found: C, 56.61;H, 3.42.
To a solution of NaOH (5.80 g, 145 mmol) in water (60
mL) was added Ag2O (13.0 g, 56.1 mmol) in water (60
mL) at room temperature. After stirring for 15 min,
21a–c (37.4 mmol) was added and the reaction mixture
was stirred at room temperature for 0.5 h, and at 50 ꢁC
for 4 h. A crystalline precipitate was filtered off and
washed with water. The filtrate and washings were
combined, poured into chilled 10% HCl (20 mL) and
extracted with ethyl acetate and THF. The extract was
washed successively with water and brine and dried over
anhydrous MgSO4. The organic solution was evapo-
rated under reduced pressure to give a residue, which
was recrystallized from solvents to give 7c–e.
Methyl 5-(4-bromophenyl)thiophene-2-carboxylate (7g).
Compound 7g was prepared from 7d and methanol,
and recrystallized from ethyl acetate–hexane as a white
powder. Yield, 83%;mp: 112 ꢁC, 1H NMR (CDCl3)
(200 MHz) d: 4.25 (s, 3H), 7.63 (d, 1H, J=5 Hz), 7.80–
7.93 (m, 4H), 8.10 (d, 1H, J=5 Hz). IR (KBr) cmꢀ1
:
3436, 2929, 1690, 1675, 1582. MS m/z 297 (M+). Anal.
calcd for C12H9BrO2S: C, 48.50;H, 3.05. Found: C,
48.45;H, 2.95.
5-(4-Chlorophenyl)thiophene-2-carboxylic acid (7c).
Compound 7c was prepared from chlorobenzene (16a),
and recrystallized from THF as a white powder. Yield,
Ethyl 5-(4-methylphenyl)thiophene-carboxylate (7h).
Compound 7h was prepared from 7e and ethanol, and
recrystallized from ethyl acetate–hexane as a white
ꢁ
1
86%;mp: 250–252 C, 1H NMR (DMSO-d6) (200 MHz)
powder. Yield, 95%;mp: 88–89 ꢁC, H NMR (CDCl3)
d: 7.45–7.55 (m, 2H), 7.55–7.65 (m, 1H), 7.70–7.85 (m,
(200 MHz) d: 1.38 (t, 3H, J=7 Hz), 2.36 (s, 3H), 4.35 (q,
2H, J=7 Hz), 7.20 (d, 2H, J=8 Hz), 7.23 (d, 1H, J=4
Hz), 7.52 (d, 2H, J=8 Hz), 7.74 (d, 1H, J=4 Hz). IR
(KBr) cmꢀ1: 2982, 1702. MS m/z 246 (M+). Anal. calcd
for C14H14O2S: C, 68.26;H, 5.73. Found: C, 68.24;H,
5.64.
3H), 13.3 (br s, 1H, D2O exchangeable). IR (KBr) cmꢀ1
:
2812, 2520, 1656, 1534, 1446. MS m/z 238 (M+). Anal.
calcd for C11H7ClO2S: C, 55.35;H, 2.96. Found: C,
55.27;H, 2.87.
5-(4-Bromophenyl)thiophene-2-carboxylic acid (7d).
Compound 7d was prepared from bromobenzene (16b),
and recrystallized from THF–hexane as a white powder.
Yield, 76%;mp: 243–245 ꢁC, 1H NMR (DMSO-d6)
(200 MHz) d: 7.55–7.95 (m, 6H), 13.2 (br s, 1H, D2O
exchangeable). IR (KBr) cmꢀ1: 2973, 1671, 1535, 1449.
MS m/z 283 (M+). Anal. calcd for C11H7BrO2S: C,
46.65;H, 2.49. Found: C, 46.50;H, 2.38.
General procedure for preparation of 8a,b
Compounds 8a,b were prepared from 7f,g in a manner
analogous to that used for the preparation of 5a–e.
[5-(4-Chlorophenyl)thiophen-2-yl]acetic acid (8a). Com-
pound 8a was prepared from 7f, and recrystallized from
ethyl acetate–hexane as colorless crystals. Yield, 66%;
ꢁ
1
5-(4-Methylphenyl)thiophene-2-carboxylic acid (7e).
Compound 7e was prepared from bromobenzene (16c),
and recrystallized from ethyl acetate–hexane as a white
powder. Yield, 76%;mp: 208–210 ꢁC, 1H NMR
(CDCl3) (200 MHz) d: 2.33 (s, 3H), 7.28 (d, 2H, J=9
Hz), 7.52 (d, 2H, J=4 Hz), 13.1 (br s, 1H). IR (KBr)
cmꢀ1: 2857, 2549, 1658, 1539, 1450. MS m/z 218 (M+).
Anal. calcd for C12H10O2S: C, 66.03;H, 4.62. Found: C,
65.98;H, 4.48.
mp: 153–155 C, H NMR (CDCl3) (200 MHz) d: 3.85
(s, 2H), 6.96 (d, 1H, J=5 Hz), 7.18 (d, 1H, J=5 Hz),
7.40–7.50 (m, 2H), 7.60–7.70 (m, 2H), 12.50–12.80 (br s,
1H). IR (KBr) cmꢀ1: 3421, 3044, 1708. MS m/z 252
(M+). Anal. calcd for C12H9ClO2S: C, 57.02;H, 3.59.
Found: C, 57.14;H, 3.54.
[5-(4-Bromophenyl)thiophen-2-yl]acetic acid (8b). Com-
pound 8b was prepared from 7g, and recrystallized from
ethyl acetate-ꢁ hexane as colorless crystals. Yield, 75%;
1
mp: 158–159 C, H NMR (CDCl3) (200 MHz) d: 3.88
General procedure for preparation of 7f–h
(s, 2H), 6.93 (d, 1H, J=5 Hz), 7.15 (d, 1H, J=5 Hz),
7.38–7.63 (m, 4H). IR (KBr) cmꢀ1: 3437, 2909, 1712.
MS m/z 297 (M+). Anal. calcd for C12H9BrO2S: C,
48.50;H, 3.05. Found: C, 48.54;H, 2.96.
To a solution of concd H2SO4 (4.3 mL), alcohol (86
mL), and toluene (40 mL) was added 7c–e (27.2 mmol),
and the mixture was stirred under reflux for 7 h. The

T. Noguchi et al. / Bioorg. Med. Chem. 11 (2003) 4729–4742
4741
General procedure for preparation of 8c,d
General procedure for preparation of 9d–f
Compounds 8c,d were prepared from 8a,b in a
manner analogous to that used for the preparation of
5f–i.
To a solution of 9a–c (23.5 mmol) in methanol (70 mL)
and THF (35 mL) was added a solution of NaOH (1.70
g, 425 mmol) in water (70 mL), and the mixture was
stirred overnight at room temperature. The resulting
solution was concentrated under reduced pressure, and
then poured into 5% HCl (100 mL). The mixture was
extracted with ethyl acetate. The extract was washed
successively with water and brine and dried over anhy-
drous MgSO4. The ethyl acetate solution was
evaporated under reduced pressure to give a residue,
which was recrystallized from ethyl acetate–hexane to
give 9d–f.
Methyl [5-(4-chlorophenyl)thiophen-2-yl]acetate (8c).
Compound 8c was prepared from 8a, and recrystallized
from methanol as colorless crystals. Yield, 67%;mp:
ꢁ
1
75–76 C, H NMR (CDCl3) (200 MHz) d: 3.75 (s, 3H),
3.85 (s, 2H), 6.90 (d, 1H, J=5 Hz), 7.13 (d, 1H, J=5
Hz), 7.28–7.38 (m, 2H), 7.45–7.55 (m, 2H). IR (KBr)
cmꢀ1: 3436, 1741. MS m/z 266 (M+). Anal. calcd for
C13H11ClO2S: C, 58.54;H, 4.16. Found: C, 58.63;H,
4.10.
2-(5-Phenylthiophen-3-yl)propionic acid (9d). Compound
9d was prepared from 9a as colorless crystals. Yield,
Methyl [5-(4-bromophenyl)thiophen-2-yl]acetate (8d).
Compound 8d was prepared from 8b, and recrystallized
from methanol as colorless crystals. Yield, 97%;mp:
92%;mp: 97 ꢁC, H NMR (CDCl3) (200 MHz) d: 1.56
1
(d, 3H, J=7 Hz), 3.85 (q, 1H, J=7 Hz), 7.07–7.70 (m,
7H). IR (KBr) cmꢀ1: 2939, 1704. MS m/z 232 (M+).
Anal. calcd for C13H12O2S: C, 67.21;H, 5.21. Found: C,
67.12;H, 5.13.
94–95ꢁC, H NMR (CDCl3) (200 MHz) d: 3.75 (s, 3H),
1
3.85 (s, 2H), 6.90 (d, 1H, J=5 Hz), 7.15 (d, 1H, J=5
Hz), 7.40–7.60 (m, 4H). IR (KBr) cmꢀ1: 3436, 1741. MS
m/z 311 (M+). Anal. calcd for C13H11BrO2S: C, 50.18;
H, 3.56. Found: C, 49.97;H, 3.48.
2-[5-(4-Chlorophenyl)thiophen-3-yl]propionic acid (9e).
Compound 9e was prepared from 9b as colorless crys-
tals. Yield, 85%;mp: 118 ꢁC, 1H NMR (CDCl3)
(200 MHz) d: 1.55 (d, 3H, J=7 Hz), 3.83 (q, 1H, J=7
Hz), 7.08–7.60 (m, 6H). IR (KBr) cmꢀ1: 2981, 1695. MS
m/z 266 (M+). Anal. calcd for C13H11ClO2S: C, 58.53;
H, 4.16. Found: C, 58.71;H, 4.04.
General procedure for preparation of 9a–c
To a solution of 5f,h,i (16.8 mmol) in DMF (40 mL)
was added NaH (60% oil suspension) (672 mg, 28.0
mmol), and the solution was stirred under ice cooling
for 0.5 h. Methyl iodide (1.05 mL, 16.9 mmol) was
added, and the stirring was continued for 3 h. The
resulting solution was poured into water (50 mL) and
extracted with ethyl acetate. The extract was washed
successively with water and brine and dried over anhy-
drous MgSO4. The ethyl acetate solution was evapo-
rated under reduced pressure to give a residue, which
was purified by silica gel column chromatography to
give 9a–c (77–83%).
2-[5-(4-Bromophenyl)thiophen-3-yl]propionic acid (9f).
Compound 9f was prepared from 9c as colorless crys-
tals. Yield, 85%;mp: 128 ꢁC, 1H NMR (CDCl3)
(200 MHz) d: 1.55 (d, 3H, J=7 Hz), 3.84 (q, 1H, J=7
Hz), 7.10–7.55 (m, 6H). IR (KBr) cmꢀ1: 2979, 1694. MS
m/z 311 (M+). Anal. calcd for C13H11BrO2S: C, 50.17;
H, 3.56. Found: C, 49.90;H, 3.44.
Biological methods
Methyl 2-(5-phenylthiophen-3-yl)propionate (9a). Com-
pound 9a was prepared from 5f as a pale yellow oil.
Yield, 83%; H NMR (CDCl3) (200 MHz) d: 1.53 (d,
IL-1-Induced thymocyte proliferation (assay of the IL-1
antagonistic effect).23 C3H/HeJ mouse thymus cells
were suspended in complete RPMI1640 medium con-
taining 100 U/mL penicillin, 100 mg/mL streptomycin,
5ꢂ10ꢀ5 mol/L 2-mercaptoethanol (Sigma, USA) and
5% fetal bovine serum at a concentration of 3ꢂ107
cells/mL. Each well of a 96-well culture plate (Nunc
Company, USA) contained the test compound in 0.05
mL of medium, 0.05 mL of cell suspension, 0.05 mL of
phytohemagglutinin (PHA) (Sigma, USA) solution (24
mg/mL), and 0.05 mL of IL-1b (Genzyme, USA) solu-
tion (24 U/mL). After 48 h of incubation at 37 ꢁC in a
CO2 incubator, cells were pulsed with 0.25 mCi of
methyl-3H-thymidine (3H-TdR, 6.7 Ci/mmol, Amer-
sham, Japan) for 16 h. The cells were harvested with an
automated cell harvester and counted in a beta scintil-
lation counter.
1
3H, J=7 Hz), 3.70 (s, 3H), 3.82 (q, 1H, J=7 Hz), 7.05–
7.65 (m, 7H). IR (neat) cmꢀ1: 2950, 1737. MS m/z 246
(M+). Anal. calcd for C14H14O2S: C, 68.26;H, 5.73.
Found: C, 68.23;H, 5.70.
Methyl 2-[5-(4-chlorophenyl)thiophen-3-yl]propionate (9b).
Compound 9b was prepared from 5h as a pale yellow
1
oil. Yield, 81%; H NMR (CDCl3) (200 MHz) d: 1.52
(d, 3H, J=7 Hz), 3.70 (s, 3H), 3.82 (q, 1H, J=7 Hz),
7.05–7.56 (m, 6H). IR (neat) cmꢀ1: 2950, 1737. MS m/z
280 (M+). Anal. calcd for C14H13ClO2S: C, 59.89;H,
4.67. Found: C, 59.71;H, 4.57.
Methyl 2-[5-(4-bromophenyl)thiophen-3-yl]propionate (9c).
Compound 9c was prepared from 5i as a pale yellow
1
oil. Yield, 77%; H NMR (CDCl3) (200 MHz) d: 1.53
(d, 3H, J=7 Hz), 3.70 (s, 3H), 3.82 (q, 1H, J=7 Hz),
7.05–7.55 (m, 6H). IR (neat) cmꢀ1: 2950, 1735. MS m/z
325 (M+). Anal. calcd for C14H13BrO2S: C, 51.70;H,
4.03. Found: C, 51.63;H, 3.91.
Suppression of AIA.25 SD rats were inoculated intrader-
mally in the tail with 0.6 mg of heat-killed Mycobacter-
ium butyricum (Difco Laboratories, USA) suspended in
0.1 mL of liquid paraffin. The test compounds, which

4742
T. Noguchi et al. / Bioorg. Med. Chem. 11 (2003) 4729–4742
were prepared as a suspension in 5% gum arabic solu-
tion, were orally administered to the rats at a daily dose
of 100 mg/kg for 20 days. In the control group, a 5%
gum arabic solution was orally administered to rats
after sensitization. Twenty-one days later, the edema
volume of the hindpaw of rats in the test compound-
treated and control groups was measured to evaluate
edema-suppressing activities. The activity toward AIA
was ranked as follows. When AIA was 0–10, 10–25, 25–
40, 40–55, 55–70, 70–85%, and more than 85%, the
activity was classified as 0, 1, 2, 3, 4, 5 and 6, respectively.
Darcy, P. J.;Trundle C. European Patent, 140,540, 1985;
Chem. Abstr. 1986, 104, 70288.
10. Ito, K.;Spears, G. W.;Takahashi, F.;Yamada, A.;
Tomishima, M.;Miyake, H. World Patent, 125,229, 2001;
Chem. Abstr. 2001, 134, 280863.
11. Gallagher, P. T.;Hicks, T. A. European Patent, 259,972,
1988; Chem. Abstr. 1988, 109, 92763.
12. Rooney, C. S.;Randall, W. C.;Streeter, K. B.;Ziegler, C.;
Cragoe, E. J., Jr.;Schwam, H.;Michelson, S. R.;Williams,
H. W. R.;Eichler, E.;Duggan, D. E.;Ulm, E. H.;Noll, R. M.
J. Med. Chem. 1983, 26, 700.
13. Fincke, H.;Bohr, H.;Staeger, S. German Patent,
1,919,381, 1969; Chem. Abstr. 1970, 72, 31599.
14. Beaton, C. M.;Chapman, N. B.;Clarke, K. J. Chem. Soc.,
Perkin Trans. 1 1976, 22, 2355.
References and Notes
15. Tomisawa, K.;Kameo, K.;Hatada, Y.;Takahashi, Y.;
Hatayama, K. Japanese Patent, 193,990, 1990; Chem. Abstr.
1990, 113, 231203.
16. Campaigne, E.;White, R. L. J., Jr. Heterocyclic Chem.
1988, 25, 367.
17. Weston, A. W.;Michaels, R. J., Jr. Org. Synth. 1962, 4, 915.
18. Tomisawa, K.;Hasegawa, M.;Mitsukuchi, M.;
Hatayama, K. World Patent, 9,602,529, 1996; Chem. Abstr.
1996, 125, 33493.
19. Surrey, A. R.;Hammer, H. F.;Suter, C. M. J. Am. Chem.
Soc. 1944, 66, 1933.
1. Takeshita, K.;Fukazawa, I.;Futaki, N.;Kameo, K.;
Tomisawa, K.;Otomo, S.;Aihara, H. Arzneim.-Forsch./Drug
Res. 1988, 38, 537.
2. Kameo, K.;Ogawa, K.;Takeshita, K.;Nakaike, S.;Tomi-
sawa, K.;Sota, K. Chem. Pharm. Bull. 1988, 36, 2050.
3. Takahashi, S.;Inoue, T.;Higaki, M.;Mizushima, Y. Drugs
Exp. Clin. Res. 1998, 24, 67.
4. Yasuda, Y.;Inoue, T.;Takeshita, K. Drugs Exp. Clin. Res.
1996, 22, 1.
5. Hashimoto, M.;Kobayashi, K.;Yamagata, N.;Katsura,
T.;Sugihara, S.;Iwabuchi, H.;Kasama, T.;Kasahara, K.;
Takahashi, T.;Takeshita, K.;Otomo, S. Agents Actions 1992,
37, 99.
20. Tomisawa, K.;Hasegawa, M.;Mitsukuchi, M.;
Hatayama, K. Japanese Patent, 194,476, 1997; Chem. Abstr.
1997, 127, 190640.
6. Noguchi, T.;Onodera, A.;Tomisawa, K.;Yokomori, S.
Heterocycles 2002, 57, 1907.
21. Moffett, R. B. Org. Synthesis 1962, 4, 291.
22. Krapcho, A. P.;Lovey, A. J. Tetrahedron Lett. 1973, 14, 957.
23. Oppenheim, J. J.;Shneyour, A.;Kook, A. I. J. Immunol.
1976, 116, 1466.
24. Oppenheim, J. J.;Kovacs, E. J.;Matsushima, K.;Durum,
S. K. Immunol. Today 1986, 7, 45.
7. Clemence, F.;Le Martret, O.;Fournex, R.;Dagnaux,
G. P. M. Eur. J. Med. Chem. Ther. 1974, 9, 390.
8. Lautenschlager, H. H.;Parnham, M. J.;Leyck, S.;Win-
kelmann J.;Brekle, A. Japanese Patent, 202,877, 1985; Chem.
Abstr. 1986, 104, 148724.
25. Mohr, W.;Wild, A. Arzneim.-Forsch./Drug Res. 1976, 26,
1860.
9. Heller, H. G.;Oliver, S. N.;Whittal, J.;Johncock, W.;