Discovery of novel indane derivatives as liver-selective thyroid hormone receptor β (TRβ) agonists for the treatment of dyslipidemia

Article abstract of DOI:10.1016/j.bmc.2012.03.056

Thyromimetics that specifically target TRβ have been shown to reduce plasma cholesterol levels and avoid atherosclerosis through the promotion of reverse cholesterol transport in an animal model. We designed novel thyromimetics with high receptor (TRβ) and organ (liver) selectivity based on the structure of eprotirome (3) and molecular modeling. We found that indane derivatives are potent and dual-selective thyromimetics expected to avoid hypothyroidism in some tissues as well as heart toxicity. KTA-439 (29), a representative indane derivative, showed the same high human TRβ selectivity in a binding assay as 3 and higher liver selectivity than 3 in a cholesterol-fed rat model.

Full text of DOI:10.1016/j.bmc.2012.03.056

Bioorganic & Medicinal Chemistry 20 (2012) 3622–3634
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Discovery of novel indane derivatives as liver-selective thyroid hormone
receptor b (TRb) agonists for the treatment of dyslipidemia
Hiroaki Shiohara a, , Tetsuya Nakamura a, Norihiko Kikuchi a, Tomonaga Ozawa a, Ryuichi Nagano a,
⇑
Akane Matsuzawa a, Hideki Ohnota a, Takahide Miyamoto b, Kazuo Ichikawa c, Kiyoshi Hashizume d
a Central Research Laboratory, Kissei Pharmaceutical Co., Ltd, 4365-1, Kashiwabara, Hotaka, Azumino-City, Nagano 399-8304, Japan
b Miyamoto Clinic, 1-6, Ryojima, Matsumoto-City, Nagano 390-0848, Japan
c Ichikawa Clinic, 1548-2, Minamiminowa-Village, Kamiina-County, Nagano 399-4598, Japan
d Matsumoto Dental University Hospital, Shiojiri-City, Nagano 399-0781, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Thyromimetics that specifically target TRb have been shown to reduce plasma cholesterol levels and
avoid atherosclerosis through the promotion of reverse cholesterol transport in an animal model. We
designed novel thyromimetics with high receptor (TRb) and organ (liver) selectivity based on the struc-
ture of eprotirome (3) and molecular modeling. We found that indane derivatives are potent and dual-
selective thyromimetics expected to avoid hypothyroidism in some tissues as well as heart toxicity.
KTA-439 (29), a representative indane derivative, showed the same high human TRb selectivity in a bind-
ing assay as 3 and higher liver selectivity than 3 in a cholesterol-fed rat model.
Received 26 February 2012
Revised 25 March 2012
Accepted 26 March 2012
Available online 11 April 2012
Keywords:
Indane
Ó 2012 Elsevier Ltd. All rights reserved.
Thyromimetics
TRb selectivity
Liver selectivity
Hypothyroidism
Dyslipidemia
1. Introduction
distributed, but its levels are generally lower than those of the
TRb1 isoform. The literature suggests that most of the effects of
Thyroid hormones (THs) affect growth, development, and
metabolism in practically all tissues.1–3 An excess quantity of cir-
culating TH, commonly referred to as hyperthyroidism, results in
increased heart rate, body temperature, osteoporosis, muscle fati-
gue, changes in mental state, and dramatic reductions in circulat-
ing cholesterol levels and body weight. THs are expected to be
potent lipid-lowering agents, but they cannot be used therapeuti-
cally in patients with dyslipidemia, obesity, or metabolic syndrome
mainly because of the side effect of tachycardia.4
THs on the heart (particularly on the rate and rhythm) are mediated
through activation of the TR 1 isoform, whereas most of the actions
a
of the hormones on the liver (e.g., lipid-lowering effect) and other
tissues are mediated through activation of the TRb1 isoform.8
Thyromimetics that specifically target TRb have been shown to
reduce plasma cholesterol levels and avoid atherosclerosis through
the promotion of reverse cholesterol transport in an animal model.
Such compounds may be useful as a complement to statin therapy
in the prevention of cardiovascular disease.8–11 However, TRb acti-
vation can be expected to reduce thyroid-stimulating hormone
(TSH) levels and thereby reduce the endogenous production of thy-
roid hormones. A reduction in TSH levels and subsequent reduction
in T4 may paradoxically cause hypothyroidism in some tissues.
Most of the selective analogs are known to reduce TSH and/or T4
levels at therapeutic doses.12 A derivative of malonamic acid,
eprotirome (KB2115; 3) (Karo Bio), is a thyroid hormone analog
with minimal uptake in non-hepatic tissues compared with T3. It
There are two major THs: thyroxine (T4; 1 in Fig. 1) and 3,5,30-
triiodo-L-thyronine (T3; 2). They exert their actions by binding to
nuclear thyroid hormone receptors (TRs) in the nucleus. There are
two major subtypes of TRs,
a (TRa) and b (TRb), expressed from
two different genes.1 Differential processing of ribonucleic acid
(RNA) results in the formation of several isoforms from each gene.
The TRa1, TRb1, and TRb2 isoforms bind THs and act as ligand-regu-
lated transcription factors.5 The TRb1 isoform is prevalent particu-
larly in the liver, and to a lower degree, in the heart.6 The TRb2
isoform is expressed in the hypothalamus, anterior pituitary gland,
and the developing brain.1,7 The TRa1 isoform is also widely
has a modestly higher affinity for TRb than for TRa. In a 2-week
clinical trial, 3 was reported to reduce serum levels of total choles-
terol, low-density lipoprotein (LDL) cholesterol, and apolipoprotein
B without evident side effects. However, in a 12-week study, serum
total and free T4 levels were modestly decreased in patients who
received eprotirome therapy.13–15
⇑
Corresponding author. Tel.: +81 (0) 263 82 8820; fax: +81 (0) 263 82 8827.
E-mail address: hiroaki_shiohara@pharm.kissei.co.jp (H. Shiohara).
0968-0896/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmc.2012.03.056

H. Shiohara et al. / Bioorg. Med. Chem. 20 (2012) 3622–3634
3623
I
O
O
6
5
5'
4'
HO
I
HO
I
I
I
OH
OH
6'
1
2
NH2
NH2
O
O
4
3'
1'
3
2'
I
I
1
2
H
N
6
H
N
5
4
HO
OH
Br
O
HO
OH
1
2
O
O
O
O
O
3
Br
3
4
Figure 1. Structures of T4 (1), T3 (2), eprotirome (3), and the reported thyroid hormone ligand (4).
We investigated novel thyromimetics that showed high recep-
tor (TRb) and organ (liver) selectivity to avoid hypothyroidism as
well as heart toxicity. In the present study, we describe the discov-
ery process and investigate the structure–activity relationships
(SARs) of novel indane derivatives.
reported method16 to give bis(4-benzyloxy-3-isopropylphenyl)
iodonium BFꢀ4 8. Commercially available 2,3,6-trisubstituted phe-
nols 9 and 10 were nitrated with NaNO2/TFA and HNO3/CH2Cl2
to give the nitrophenols 11 and 12, which were coupled with the
salt 8 to give the diphenyl ethers 13 and 14, respectively. Nitro
group reduction of 13 with H2/Pt gave the aniline 15, which was
coupled with ethyl malonyl chloride to give the anilide 16. Deben-
zylation of 16 with TFA/H2O/Me2S (95/5/10) gave the ester 17,20
which was hydrolyzed to give the final target ligand 18. Nitro
group reduction and debenzylation of 14 with H2/Pd gave the
aniline 19. The coupling and hydrolysis of 19 as described above
gave the malonamic acid 20.
2. Strategy
We designed the compounds based on 3 because it showed
modestly high TRb selectivity in vitro and modest liver selectivity
in a clinical trial.14,15 The mechanism of liver selectivity is uncer-
tain. Yokoyama et al. reported that some compounds with high po-
tency for the nucleus and with significantly lower binding affinity
to the membrane showed separation of lipid-lowering effects from
cardiac effects in rats.16 However, it was uncertain whether these
compounds also showed separation of lipid-lowering effects from
the negative feedback of T4. Conversely, TRb potency and selectiv-
ity can be evaluated in vitro. Hence, we first evaluated TRb selectiv-
ity in vitro and then evaluated liver selectivity in vivo using
synthesized compounds.
3.3. Synthesis of malonamic acids with fused rings
We prepared malonamic acids in which an additional ring was
fused to the inner ring between the 2-position and 3-position, as
outlined in Scheme 2. Known 22a,21 23,22 and 5-bromoindan-4-ol
22b, which was prepared from the known indan-4-ol 21, were ni-
trated with HNO3/CH2Cl2 to give 24a, 25, and 24b, respectively. The
nitro compounds 24a, 24b, and 25 were coupled with the salt 8 to
give the ethers 26a, 26b, and 27, respectively. Nitro group reduc-
tion and debenzylation of 26a with H2/Pd gave the aromatic amine
28. Coupling and hydrolysis of 28 as described above gave the tar-
get compound 29. Nitro group reduction of 26b and 27 with H2/Pt
gave the aromatic amines 30 and 31, which were coupled with
ethyl malonyl chloride to give the amides 32 and 33, respectively.
Debenzylation and alkaline hydrolysis of 32 and 33 gave the fused
compounds 34 and 35, respectively.
3. Results and discussion
3.1. First design of the target
Only one amino acid is different from hTR
a and hTRb in the
hormone-binding pocket (Ser-277 vs Asn-331, respectively).17
The crystal structures of hTRs bound to T3 revealed that hydrogen
bonds were formed between the Arg-228a/282b of hTRs and COOH
of T3 but not between the Ser-277
a/Asn-331b of hTRs and T3
(Fig. 2a, b).18
3.4. In vitro effects of the ligands on TRs
A docking model of 3 was constructed from the crystal structure
of hTRb–T3 complex (Fig. 2c). The docking model suggested the pos-
sibility that interactions occur between NH of 3 and Asn-331 of
The results of a radioligand binding assay for hTR
well as a reporter cell assay employing COS1 cells stably transfec-
ted with hTR or hTRb and the luciferase reporter gene down-
stream the thyroid response element are summarized in Table 1.
The natural ligand T3 (2) bound to hTR and hTRb with Ki of 2.29
and 2.33 nM, respectively. Compound 3 was found to be selective
for hTRb over hTR with regard to binding. When the bromine
a and hTRb as
a
hTRb and between COOH of 3 and Arg-266a/320b but not between
NH of 3 and Ser-277 of hTR . We supposed that these different
a
a
interactions affect the hTRb selectivity of 3, which was higher than
that of T3. The model also suggested that the hTRb–ligand complex
showed an unoccupied space in the binding cavity next to the 2-po-
sition of 3 (Fig. 2d). Filling of this space was expected to stabilize the
complex. Hence, we first decided to synthesize new malonamic acid
derivatives with a substituent at the 2-position.19
a
atom was replaced with methyl groups (compound 413), binding
affinities decreased for both isoforms, thereby resulting in high
hTRb selectivity. Substitution of the methyl group at the 2-position
of 4 as in 20 did not affect affinity and selectivity. The trihalogen-
ated compound 18 also showed similar affinity and selectivity to 3.
Interestingly, the indane compounds in which the alkyl ring was
fused on the inner ring between the 2-position and 3-position
(29, 34) showed high affinity for hTRb and selectivity for hTRb over
3.2. Synthesis of malonamic acids with a substituent at the 2-
position
Two malonamic acid derivatives with a substituent at the 2-po-
sition were prepared, as outlined in Scheme 1. Benzylation of the
commercially available 5 gave the benzyl ether 6, which was
treated with (CF3CO2)3I 7 prepared from I2 following a previously
hTRa. However, the 5,6,7,8-tetrahydronaphthalene compound 35
showed lower affinity for hTRb, resulting in diminished selectivity.
All compounds displayed full agonism in the reporter cell assay.

3624
H. Shiohara et al. / Bioorg. Med. Chem. 20 (2012) 3622–3634
(a)
(b)
(c)
Arg228
Arg282
Arg282
Asn331
Arg320
Arg266
Arg320
Asn331
Ser277
(d)
Figure 2. (a), (b) Interactions observed in the published crystallographic structures of ligand binding domain (LBD)–ligand complexes. (a) T3 and hTR
a
and (PDB code 2H79),
(b) T3 and hTRb (PDB code 3GWS). Hydrogen bonds or polar interactions are observed between COOH of T3 and Arg-228
a
/282b of hTRs but not between T3 and Ser-277 /Asn-
a
331b of hTRs.18 (c), (d) The docking model of hTRb with eprotirome (3) constructed from the crystal structure of hTRb–T3 complex. (PDB code 3GWS). (c) Interactions between
3 and hTRb. Hydrogen bonds are possible between NH of 3 and Asn-331b and between COOH of 3 and Arg-320b. (d) The hTRb–ligand complex showed an unoccupied space in
the binding cavity next to the 2-position of 3.
OH
R
NO2
R
R
OBn
a
b
HO
R
HO
R
R
5
6
9: R = Cl
10: R = CH3
11: R = Cl
12: R = CH3
CF3
BnO
R
O
NO2
R
O
O
O
O
I
BnO
OBn
c
d
e
I2
CF3
O
I+
R
F
B
F
O
CF3
F
F
7
8
13: R = Cl
14: R = CH3
O
O
CO2Et
CO2Et
NH2
BnO
Cl
BnO
Cl
NH
Cl
HO
Cl
NH
f
g
h
13
Cl
O
O
O
Cl
Cl
Cl
16
Cl
15
17
i
O
O
CO2H
CO2H
HO
Cl
NH
Cl
HO
NH2
HO
NH
j
g, i
14
O
O
O
Cl
18
19
20
Scheme 1. Synthetic route for the preparation of 18 and 20. Reagents and conditions: (a) BnBr, K2CO3, CH3CN; (b) (R = Cl) NaNO2, TFA; (R = CH3) HNO3, CH2Cl2; (c) HNO3
(fuming), TFA; (d) (i) 6, CH2Cl2; (ii) NaBF4, MeOH; (e) 11 or 12, Cu, Et3N, CH2Cl2, 5 days; (f) H2/PtO2, EtOAc; (g) ClCOCH2CO2Et, pyridine, CH2Cl2, 0 °C; (h) TFA/H2O/Me2S (95/5/
10); (i) NaOH, MeOH; (j) H2/Pd-C, EtOAc.

H. Shiohara et al. / Bioorg. Med. Chem. 20 (2012) 3622–3634
3625
R1
Br
R1
NO2
NO2
BnO
R1
O
a
b
c
HO
HO
HO
HO
R1
( )n
( )n
( )n
21
22b
R1
n
n
R1
n
Me
Br
Br
1
1
2
Me
Br
Br
1
1
2
Me
Br
Br
1
1
2
22a
22b
23
24a
24b
25
26a
26b
27
O
CO2H
NH2
NH
HO
HO
d
e, f
26a
O
O
28
29
O
O
CO2Et
h, f
CO2H
BnO
Br
NH2
BnO
Br
NH
NH
HO
Br
g
e
26b
27
O
O
O
( )n
( )n
( )n
n = 1 30
n = 2 31
n = 1 32
n = 2 33
n = 1 34
n = 2 35
Scheme 2. Synthetic route for the preparation of 29, 34, and 35. Reagents and conditions: (a) N-Bromosuccinimide, iPr2NH, CH2Cl2, 0 °C; (b) HNO3, AcOH; (c) 8, Cu, Et3N,
CH2Cl2, 5 days; (d) H2/Pd-C, EtOAc; (e) ClCOCH2CO2Et, pyridine, CH2Cl2, 0 °C; (f) NaOH, MeOH; (g) H2/PtO2, EtOAc; (h) TFA/H2O/Me2S (95/5/10).
3.5. Next design: synthesis of indane derivatives with other
acids and spacers
prepared by diazotization, iodization, palladium-catalyzed cyana-
tion, and alkaline hydrolysis. Coupling with glycine ethyl ester
gave the amide 41. Debenzylation of 41 with TFA/H2O/Me2S (95/
5/10) gave the deprotected product 42, which was hydrolyzed to
give the carbonylaminoacetic acid 43.
The benzyl ether 6 was treated with Cl2CHOCH3/TiCl4 to give
the aldehyde 44. Triflation of the nitro compound 24a with Tf2O
followed by iodization gave the iodoindane 45. Nitro group reduc-
tion of 45 with H2/Pt gave the aromatic amine 46, which was ben-
zylated to give 47. The aldehyde 44 was coupled with a lithiated
compound from the iodide 47 to give the biaryl alcohol 48, which
was hydrogenolyzed to give the biarylmethane 49. Coupling
The previously unknown indane derivatives were found to have
high hTRb potency and selectivity. Hence, we synthesized other in-
dane derivatives with other acids and ring spacers to obtain further
SAR information, as outlined in Scheme 3. The aromatic amine 28
was condensed with diethyl oxalate to give the oxamate 36, which
was hydrolyzed to give the oxamic acid 37. Coupling of 28 with
ethyl (chlorosulfonyl)acetate followed by hydrolysis gave the sul-
famoylacetic acid 38. Nitro group reduction of 26a with H2/Pt gave
the aromatic amine 39 from which the carboxylic acid 40 was
Table 1
Thyroid hormone receptor binding affinities (Ki) and reporter cell line potency efficacies (% agonism) of compounds 2–4, 18, 20, 29, 34, and 35
H
N
6
1
OH
HO
R1
5
2
O
O
R3
4
O
3
R2
Compound
R1
R2
R3
Ki (nM)a
a
/bb
% Agonismc
hTRb
2.29
0.43
10.0
1.54
20.3
7.80
1.19
301
hTR
2.33
9.60
147
24.4
195
172
69.3
300
a
TRLuc-b
TRLuc-a
2
3
4
18
20
29
34
35
1
22
15
16
10
22
58
1
100
111
180
108
123
113
93
100
98
107
120
95
110
106
124
Br
Me
Cl
Me
Me
Br
Br
Me
Cl
Me
H
H
Cl
Me
CH2CH2CH2
CH2CH2CH2
CH2(CH2)2CH2
Br
115
a
b
c
Values are means of two experiments. On average, the variability was 25%.
Selectivity (Ki hTR )/(Ki hTRb).
Values at 10ꢀ5 M; T3 as 100%.
a

3626
H. Shiohara et al. / Bioorg. Med. Chem. 20 (2012) 3622–3634
O
CO2H
NH
O
CO2Et
NH
HO
HO
HO
HO
NH2
a
b
O
O
O
28
36
37
c, b
O
O
S
NH
CO2H
O
38
BnO
NH2
BnO
CO2H
BnO
NO2
d
e
f
O
O
O
26a
39
40
O
O
O
HO
HO
BnO
N
H
CO2Et
N
CO2H
N
H
CO2Et
H
g
b
O
O
O
43
41
42
BnO
BnO
h
O
6
44
NO2
NO2
NH2
NBn2
i
d
j
k
I
HO
I
I
24a
45
46
47
H
NBn2
NH2
BnO
HO
N
HO
HO
CO2H
l
m, b
O
OH
48
49
50
53
n
H
NBn2
NH2
BnO
HO
N
CO2H
o
m, b
O
O
O
O
51
52
Scheme 3. Synthetic route for the preparation of 37, 38, 43, 50, and 53. Reagents and conditions: (a) (CO2Et)2, 110 °C; (b) NaOH, MeOH; (c) ClSO2CH2CO2Et, pyridine, CH2Cl2,
0 °C; (d) H2/PtO2, EtOAc; (e) (i) NaNO2, ii) KI, (iii) Zn(CN)2, Pd(dba)2, DPPF, NMP, 80 °C, (iv) NaOH, EtOH, reflux; (f) NH2CH2CO2Et HCl, EDCI, HOBt, Et3N, DMF; (g) TFA/H2O/
Me2S (95/5/10); (h) Cl2CHOCH3, TiCl4; (i) (i) Tf2O; (ii) KI; (j) BnBr, Cs2CO3, DMF; (k) (i) tBuLi, THF, ꢀ100 °C; (ii) 44; (l) H2/Pd-C, HCl, EtOH, 50 °C; (m) ClCOCH2CO2Et, pyridine,
CH2Cl2, 0 °C; (n) MnO2, CH2Cl2; (o) H2/Pd-C, THF.
between compound 49 and ethyl malonyl chloride and hydrolysis
as described above gave the carboxylic acid 50. Oxidation of the
alcohol 48 with MnO2 gave the ketone 51. Hydrogenolysis of 51
provided the aromatic amine 52, which was coupled with ethyl
malonyl chloride and hydrolyzed to give 53.
3.6. In vitro effects of indane derivatives with other acids and
spacers on TRs
The in vitro results of indane derivatives are summarized in
Table 2. The oxamic acid 37, which has COOH at a shorter distance

H. Shiohara et al. / Bioorg. Med. Chem. 20 (2012) 3622–3634
3627
Table 2
effects cholesterol lowering at the liver and T4 lowering at the pitu-
itary gland. Eprotirome 3 showed similar cholesterol lowering as
observed with T3 and improved the potency ratio; this indicates
that 3 was more liver selective than T3. Surprisingly, 29 and 34
were more selective than 3 for cholesterol lowering versus T4 low-
ering. In all compounds, the most potent cholesterol-lowering ef-
fect was observed with 37, which also showed highest liver
Thyroid hormone receptor binding affinities (Ki) and reporter cell line potency
efficacies (% agonism) of compounds 29, 37, 38, 43, 50, and 53
HO
Y
OH
O
A
selectivity (although it was non-selective for hTRb over hTRa).
Compound
A
Y
Ki (nM)a
hTRb
a
/bb % Agonismc
TRLuc-b TRLuc-a
Moreover, 43 and 50 showed more liver selectivity than 3. The re-
sults detailed above indicated that the novel indane derivatives
were more liver selective than T3 and 3.
hTR
a
29
37
43
38
50
53
O
O
O
O
NHCOCH2
NHCO
CONHCH2
NHSO2CH2 213
NHCOCH2
7.80 172
2.59 2.45
15.1
22
1
8
6
8
113
105
99
110
95
114
81
127
1246
154
Ntd
4. Conclusion
93
CH2
19.7
59.0
90
98
We designed novel thyromimetics with high receptor (TRb) and
organ (liver) selectivity based on the structure of eprotirome (3)
and molecular modeling. We found that indane derivatives are po-
tent and dual-selective thyromimetics expected to avoid hypothy-
roidism. The interaction between COOH of the ligand and Arg-320b
plays a central role in hTRb selectivity, and the indane structure is
the key for high liver selectivity. KTA-439 (29), a representative in-
dane derivative, showed the same high human TRb selectivity in a
binding assay as 3 and higher liver selectivity than 3 in a choles-
terol-fed rat model.
C@O NHCOCH2
ꢀ
115
64
a
b
c
Values are means of two experiments. On average, the variability was 25%.
Selectivity (Ki hTRa)/(Ki hTRb).
Values at 10ꢀ5 M; T3 as 100%.
d
Nt = not tested.
Table 3
ED values and the potency ratio for 2, 3, 29, 34, 37, 43, and 50 in a cholesterol-fed rat
modela
Compound
ED50 Chol (nmol/kg)
ED30 T4 (nmol/kg)
T4/Cholb
We expect the novel indane derivatives to be a new generation
of thyromimetics for the treatment of dyslipidemia and to have an
improved therapeutic window between the lowering of cholesterol
and T4.
2 (T3)
3 (Eprotirome)
29 (KTA-439)
34
37
43
50
5.95
9.06
21.9
105
2.80
111
1.87
25.0
0.31
2.8
28
9.5
30
611
997
85.2
2030
388
18
13
5. Experimental
30.0
a
5.1. Chemistry: general
Subcutaneous administration for 2 days. n = 3.
Ratio (ED30 T4)/(ED50 Chol).
b
Melting points were taken on a Yanako MP-3S Micro melting
point apparatus and were uncorrected. 1H and 13C NMR spectra were
recorded using Bruker Avance II+ 400 or Avance III 600 instruments,
and chemical shifts were reported in parts per million (d) downfield
from tetramethylsilane as the internal standard. Peak patterns were
shown using the following abbreviations: br, broad; s, singlet; d,
doublet; t, triplet; q, quartet; and m, multiplet. The mass spectra
(HRMS) were obtained using an Agilent Technologies 6520 Accu-
rate-Mass Q-TOFinstrument. Silica gel 60F254-precoated glass plates
from Merck KgaA or aminopropyl silica gel (APS)-precoated NH
plates from Fuji Silysia Chemical Ltd were used for thin layer chro-
matography (TLC). Flash or medium-pressure liquid chromatogra-
phy (MPLC) was performed on silica gel BW-350 from Fuji Silysia
from the inner ring than the malonamic acid 29, showed improved
hTRb potency but no hTRb selectivity. The carbonylaminoacetic
acid 43, which has an inverse CONH to 29, showed reduced hTRb
selectivity. These results suggested that the interaction between
COOH of the ligand and Arg-320b plays a central role in hTRb selec-
tivity and that the interaction between NH of the ligand and Asn-
331b plays a peripheral role. The COOH–Arg-320b interaction
might be more favorable than the COOH–Arg-266a interaction
when the ligand has COOH at a similar distance from the inner ring
to 29/43. The sulfamoylacetic acid 38, which replaced NHCO of 29
with NHSO2 and was expected to have a similar COOH–Arg-320b
interaction and NH–Asn-331b interaction, showed decreased hTRb
potency but slightly retained hTRb selectivity. The methylene com-
pound 50, which replaced the O-ring spacer of 29 with CH2 and
was also expected to have similar interactions, showed slightly de-
creased hTRb potency and selectivity. The ketone 53 also showed
decreased hTRb potency. All compounds displayed full agonism
in the reporter cell assay. From the results detailed above, we con-
cluded that an indane malonamic acid with an O-ring spacer was
the best form with regard to hTRb potency and selectivity.
Chemical Ltd or APS Daisogel IR-60 (particle size, 25–40 lM) from
Daiso Co., Ltd. All reagents and solventswere commercially available
unless otherwise indicated. Purchased reagents and solvents were
used without further purification unless otherwise noted.
5.1.1. 1-Benzyloxy-2-isopropylbenzene (6)
Benzyl bromide (75.2 mL, 632 mmol) and K2CO3 (107 g,
774 mmol) were added to
a solution of 2-isopropylphenol
(87.2 g, 640 mmol) in acetonitrile (500 mL), and the mixture was
refluxed for 29 h. The reaction mixture was evaporated under re-
duced pressure to dryness. After adding water, the mixture was ex-
tracted with EtOAc. The organic layer was washed with 1 M NaOH,
water, and brine and dried over anhydrous MgSO4. The solvent was
removed under reduced pressure to give 6 (142 g, 98%) as a color-
less oil. 1H NMR (400 MHz, CDCl3) d: 1.24 (6H, d, J = 6.9 Hz), 3.42
(1H, heptet, J = 6.9 Hz), 5.08 (2H, s), 6.88–6.97 (2H, m), 7.12–7.17
(1H, m), 7.22–7.25 (1H, m), 7.30–7.47 (5H, m); 13C NMR
(100 MHz, CDCl3) d: 22.7, 26.8, 69.9, 111.7, 120.9, 126.1, 126.5,
3.7. In vivo effects of the ligands on a cholesterol-fed rat model
The cholesterol- and T4-lowering effects of the new compounds
were assessed in a cholesterol-fed rat model via subcutaneous
administration. The in vivo results are summarized in Table 3.
The data are shown as ED50 for cholesterol (dose causing 50%
greater lowering from the vehicle) and ED30 for T4. The natural li-
gand T3 reduced cholesterol and T4 levels. The potency ratio
(obtained by dividing ED30 of T4 by ED50 of cholesterol) showed
that T4 lowering was more severe than cholesterol lowering. T3
127.1, 127.7, 128.5, 137.4, 137.6, 155.9; HRMS calcd for C16H19
O
(M+H)+ 227.1430, found 227.1429.

3628
H. Shiohara et al. / Bioorg. Med. Chem. 20 (2012) 3622–3634
5.1.2. Bis-(4-benzyloxy-3-isopropylphenyl)iodonium
tetrafluoroborate (8)
(1H, d, J = 8.8 Hz), 6.89 (1H, d, J = 3.1 Hz), 7.29–7.57 (5H, m), 7.95
(1H, s); 13C NMR (100 MHz, CDCl3) d: 22.5, 27.2, 70.6, 111.6,
112.3, 112.8, 114.4, 115.6, 125.0, 127.1, 127.9, 128.6, 128.8, 132.3,
137.3, 139.7, 145.5, 150.1, 152.2; HRMS calcd for C22H19Cl3NO4
(M+H)+ 466.0374, found 466.0357.
Fuming nitric acid (80.8 mL, 1754 mmol) was added to Ac2O
(201 mL, 2130 mmol) under ice cooling. Then, iodine (67.4 g,
266 mmol) was added to this reaction mixture. Later, TFA (154 mL,
1999 mmol) was added dropwise. After stirring at room temperature
for 1 h, the mixture was evaporated under reduced pressure at <35 °C
to dryness. Ac2O (250 mL) and 6 (141 g, 623 mmol) were then added
to the residue. Later, TFA (50 mL) was added dropwise under ice cool-
ing. Afterstirringat4 °Cfor16 h,the reaction mixturewasevaporated
under reduced pressure at <35 °C to dryness. MeOH (500 mL), an
aqueous solution of potassium metabisulfite (50 g/250 mL), and a
4.5 mol/L aqueous solution of NaBF4 (700 mL) were added to the res-
idue, successively. The mixture was stirred for 30 min. After the pre-
cipitate was aggregated, the supernatant was decanted. The residue
was dissolved in CH2Cl2 (1000 mL), and the organic layer was washed
with a 4.5 mol/L aqueous solution of NaBF4 (250 mL) and dried over
anhydrous MgSO4. The solvent was removed under reduced pressure.
The residue was triturated with diethyl ether. The insoluble material
was collected by filtration to give 8 (146 g, 92%) as a beige solid. Beige
solid; mp 152–155 °C; 1H NMR (400 MHz, CDCl3) d: 1.20 (12H, d,
J = 6.9 Hz), 3.35 (2H, heptet, J = 6.9 Hz), 5.11 (4H, s), 6.95 (2H, d,
J = 8.9 Hz), 7.26–7.53 (10H, m), 7.69 (2H, d, J = 2.4 Hz), 7.78 (1H, dd,
J = 2.4, 8.9 Hz); 13C NMR (100 MHz, CDCl3) d: 22.2, 27.5, 70.4, 103.0,
115.1, 127.2, 128.3, 128.8, 132.8, 134.5, 135.8, 142.6, 159.3; HRMS
calcd for C32H34IO2 (M)+ 577.1598, found 577.1591.
5.1.6. 2-(4-Benzyloxy-3-isopropylphenoxy)-1,3,4-trimethyl-5-
nitrobenzene (14)
The title compound was prepared from 12 in a manner similar
to that described for 13 as a white solid (65%). White solid; mp 85–
87 °C (hexane); 1H NMR (400 MHz, CDCl3) d: 1.20 (6H, d,
J = 6.9 Hz), 2.14 (3H, s), 2.15 (3H, s), 2.41 (3H, s), 3.38 (1H, heptet,
J = 6.9 Hz), 5.01 (2H, s), 6.28 (1H, dd, J = 3.1, 8.8 Hz), 6.74 (1H, d,
J = 8.8 Hz), 6.79 (1H, d, J = 3.1 Hz), 7.28–7.47 (5H, m), 7.58 (1H,
s); 13C NMR (100 MHz, CDCl3) d: 13.4, 15.8, 16.5, 22.6, 27.1, 70.7,
110.9, 112.6, 113.6, 124.4, 127.1, 127.8, 128.5, 130.3, 130.8,
133.1, 137.5, 139.6, 147.5, 151.0, 151.4, 154.5; HRMS calcd for
C
25H28NO4 (M+H)+ 406.2013, found 406.2011.
5.1.7. 4-(4-Benzyloxy-3-isopropylphenoxy)-2,3,5-trichloro
phenylamine (15)
PtO2 (38 mg, 0.167 mmol) was added to a solution of 13
(0.790 mg, 1.69 mmol) in EtOAc (30 mL). The mixture was stirred
under a hydrogen atmosphere at room temperature for 2 h. Insol-
uble materials were removed by filtration. The filtrate was evapo-
rated under reduced pressure to dryness to give 15 (0.740 g, 100%)
as a colorless amorphous solid. 1H NMR (400 MHz, CDCl3) d: 1.70–
1.94 (4H, m), 2.04 (6H, s), 2.68–2.95 (4H, m), 3.47 (2H, s), 4.96 (2H,
s), 6.02–6.12 (1H, m), 6.38–6.54 (3H, m), 7.20–7.50 (5H,m); 13C
NMR (100 MHz, CDCl3) d: 22.6, 27.2, 70.6, 111.1, 112.3, 113.9,
114.0, 115.6, 117.0, 127.1, 127.7, 128.3, 128.5, 137.6, 139.2,
139.9, 141.5, 151.4, 151.4; HRMS calcd for C22H21Cl3NO2 (M+H)+
436.0632, found 436.0631.
5.1.3. 2,3,6-Trichloro-4-nitrophenol (11)
To a mixture of 2,3,6-trichlorophenol (3.58 g, 18.1 mmol) and tri-
fluoroacetic acid (TFA) (15 mL), sodium nitrite (4.02 g, 58.2 mmol)
was added in small portions. After stirring at room temperature
overnight, the mixture was added to ice water (100 mL). The organic
layer was separated, and the aqueous layer was extracted with
CH2Cl2. The combined organic layers were washed with brine, dried
over anhydrous MgSO4, and evaporated. The residue was crystal-
lized from a small amount of EtOAc and hexane to give 11 (3.28 g,
75%) as a beige solid. Beige solid; mp 147–149 °C (dec) (EtOAc–hex-
ane); 1H NMR (400 MHz, DMSO-d6) d: 8.28 (1H, s); 13C NMR
(100 MHz, DMSO-d6) d: 120.4, 123.1, 125.0, 125.5, 139.7, 154.9;
HRMS calcd for C6HCl3NO3 (MꢀH)ꢀ 239.9027, found 239.9029.
5.1.8. Ethyl N-[4-(4-benzyloxy-3-isopropylphenoxy)-2,3,5-tri
chlorophenyl]malonamate (16)
To a solution of 15 (132 mg, 0.302 mmol) and pyridine (0.046 mL,
0.361 mmol) in CH2Cl2 (5 mL), ethyl malonyl chloride (0.046 mL,
0.361 mmol) was added dropwise at 0 °C. The mixture was stirred
at room temperature for 3 h. After adding 1 M HCl (5 mL), the reac-
tion mixture was extracted with EtOAc. The organic layer was
washed with a saturated aqueous solution of NaHCO3 and brine
and dried over anhydrous MgSO4. The solvent was removed under
reduced pressure. The residue was purified by column chromatogra-
phy on silica gel (eluent: hexane/EtOAc = 19/1–1/1) to give 16
(157 mg, 94%) as a colorless amorphous solid. 1H NMR (600 MHz,
CDCl3) d: 1.21 (6H, d, J = 6.9 Hz), 1.35 (3H, t, J = 7.1 Hz), 3.36 (1H,
heptet, J = 6.9 Hz), 3.56 (2H, s), 4.31 (2H, q, J = 7.1 Hz), 5.02 (2H, s),
6.41 (1H, dd, J = 3.1, 8.9 Hz), 6.76 (1H, d, J = 8.9 Hz), 6.87 (1H, d,
J = 3.1 Hz), 7.29–7.47 (5H, m), 8.60 (1H, s), 10.06 (1H, s); 13C NMR
(150 MHz, CDCl3) d: 14.1, 22.5, 27.2, 41.4, 62.3, 70.6, 111.3, 112.3,
112.8, 114.0, 120.7, 121.7, 127.2, 127.8, 128.5, 129.3, 133.1, 137.5,
139.3, 144.6, 150.9, 151.6, 163.3, 169.7; HRMS calcd for
5.1.4. 2,3,6-Trimethyl-4-nitrophenol (12)
To a solution of 2,3,6-trimethylphenol (4.61 g, 33.8 mmol) in
CH2Cl2 (50 mL), nitric acid (60%, 3.10 mL, 40.7 mmol) was added in
small portions at 40 °C. After refluxing for 20 min, the mixture was
washed with brine and dried over anhydrous MgSO4. The solvent
was removed under reduced pressure. The residue was crystallized
from a small amount of CH2Cl2 and hexane to give 12 (2.01 g, 33%) as
a beige solid. Beige solid; mp 99–101 °C (CH2Cl2–hexane); 1H NMR
(400 MHz, DMSO-d6) d: 2.18 (3H, s), 2.21 (3H, s), 2.32 (3H, s), 7.58
(1H, s), 9.41 (1H, br s); 13C NMR (100 MHz, DMSO-d6) d: 12.6, 15.6,
16.3, 122.4, 124.1, 124.8, 130.4, 142.4, 157.2; HRMS calcd for
C9H12NO3 (M+H)+ 182.0812, found 182.0811.
C
27H27Cl3NO5 (M+H)+ 550.0949, found 550.0951.
5.1.5. 2-(4-Benzyloxy-3-isopropylphenoxy)-1,3,4-trichloro-5-
nitrobenzene (13)
5.1.9. Ethyl N-[2,3,5-trichloro-4-(4-hydroxy-3-isopropylphen
oxy)phenyl]malonamate (17)
To a mixture of 11 (2.45 g, 10.1 mmol) and 8 (7.36 g, 11.1 mmol)
in CH2Cl2 (35 mL), copper bronze (1.99 g, 31.3 mmol) and ET3N
(2.0 mL, 14.3 mmol) were added at room temperature. The mixture
was stirred at room temperature for 5 days. The insoluble materials
were removed by filtration. The filtrate was evaporated under re-
duced pressure to dryness. The residue was purified by column
chromatography on silica gel (eluent:hexane/EtOAc 1/0–3/1) to
give 13 (3.09 g, 65%) as a beige solid. Beige solid; mp 80–83 °C (hex-
ane); 1H NMR (400 MHz, CDCl3) d: 1.22 (6H, d, J = 6.9 Hz), 3.39 (1H,
heptet, J = 6.9 Hz), 5.03 (2H, s), 6.42 (1H, dd, J = 3.1, 8.8 Hz), 6.78
16 (153 mg, 0.278 mmol) was dissolved in a mixed solvent of
TFA/water /Me2S (95/5/10, 3 mL). The mixture was allowed to stand
at room temperature overnight. The solvent was removed under re-
duced pressure, and the residue was purified by column chromatog-
raphy on silica gel (eluent: hexane/EtOAc = 19/1–0/1) to give 17
(97 mg, 76%) as a colorless amorphous solid. 1H NMR (400 MHz,
CDCl3) d: 1.23 (6H, d, J = 6.9 Hz), 1.35 (3H, t, J = 7.1 Hz), 3.18 (1H, hep-
tet, J = 6.9 Hz), 3.56 (2H, s), 4.30 (2H, q, J = 7.1 Hz), 4.88 (1H, s), 6.37
(1H, dd, J = 3.0, 8.7 Hz), 6.63 (1H, d, J = 8.7 Hz), 6.81 (1H, d,

H. Shiohara et al. / Bioorg. Med. Chem. 20 (2012) 3622–3634
3629
J = 3.0 Hz), 8.58 (1H, s), 10.07 (1H, s); 13C NMR (100 MHz, CDCl3) d:
14.1, 22.4, 27.4, 41.4, 62.3, 112.0, 113.9, 115.7, 120.8, 121.8, 128.6,
129.3, 133.0, 136.2, 144.7, 148.3, 150.9, 163.4, 169.7; HRMS calcd
for C20H21Cl3NO5 (M+H)+ 460.0480, found 460.0490.
2.16 (2H, m), 2.83–2.95 (4H, m), 5.45 (1H, s), 6.69 (1H, d, J = 8.0 Hz),
7.22 (1H, d, J = 8.0 Hz); 13C NMR (100 MHz, CDCl3) d: 21.2, 21.7,
22.6, 25.0, 26.7, 27.2, 70.6, 111.0, 112.4, 113.9, 114.8, 126.9, 127.2,
127.8, 25.4, 29.9, 33.1, 107.3, 117.7, 129.8, 131.1, 146.5, 148.4; HRMS
calcd for C9H8BrO (MꢀH)ꢀ 210.9764, found 210.9765.
5.1.10. N-[2,3,5-Trichloro-4-(4-hydroxy-3-isopropylphenoxy)
phenyl]malonamic acid (18)
5.1.14. 5-Methyl-7-nitroindan-4-ol (24a)
Toasolution of 17 (74 mg, 161 mmol)inMeOH(5 mL),anaqueous
solution of 1 M NaOH (5 mL) was added. The mixture was stirred un-
der an argon atmosphere at 50 °C for 30 min. After adding 1 M HCl
(5 mL) and brine (10 mL), the mixture was extracted twice with
EtOAc (10 mL). The organic layer was washed with brine, dried over
anhydrous MgSO4, and evaporated under reduced pressure. The res-
idue was purified by column chromatography on silica gel (eluent:
CH2Cl2/MeOH = 1/0–9/1) to give 18 (32 mg, 46%) as a white solid.
White solid; mp 143–146 °C (dec) (EtOH–H2O); 1H NMR (600 MHz,
DMSO-d6) d: 1.13 (6H, d, J = 6.9 Hz), 3.15 (1H, heptet, J = 6.9 Hz),
6.30 (1H, dd, J = 3.0, 8.7 Hz), 6.68 (1H, d, J = 8.7 Hz), 6.72 (1H, d,
J = 3.0 Hz), 8.53 (1H, br s), 9.16(1H, br s), 12.95 (1H, br s); 13C NMR
(150 MHz, DMSO-d6) d: 22.3, 26.6, 43.9, 111.2, 112.9, 115.3, 120.6,
121.7, 126.9, 128.3, 134.9, 135.8, 142.8, 149.2, 149.8, 168.7, 169.8;
HRMS calcd for C18H17Cl3NO5 (M+H)+ 432.0167, found 432.0176.
To a solution of 22a21 (8.68 g, 58.6 mmol) in AcOH (80 mL), ni-
tric acid (60%, 4.50 mL, 59.1 mmol) was added over 5 min under ice
cooling. After stirring for 5 min at 0 °C, the mixture was stirred at
room temperature. The solvent was removed under reduced pres-
sure. The residue was crystallized from a small amount of CH2Cl2
and hexane to give 24a (2.19 g, 19%) as a beige solid. Beige solid;
mp 172–174 °C (EtOH); 1H NMR (400 MHz, CDCl3) d: 2.15–2.25
(2H, m), 2.29 (3H, s), 2.85–2.95 (2H, m), 3.55–3.45 (2H, m), 5.19
(1H, br s), 7.90 (1H, s); 13C NMR (100 MHz, CDCl3) d: 15.3, 24.8,
28.8, 34.8, 122.9, 126.0, 131.0, 138.7, 141.8, 155.2; HRMS calcd
for C10H12NO3 (M+H)+ 194.0812, found 194.0808.
5.1.15. 5-Bromo-7-nitroindan-4-ol (24b)
The title compound was prepared from 22b in a manner similar
to that described for 24a as a beige solid (34%). Beige solid; mp
148–149 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3) d: 2.13–
2.26 (2H, m), 2.95–3.02 (2H, m), 3.36–3.43 (2H, m), 6.04 (1H, s),
8.25 (1H, s); 13C NMR (100 MHz, CDCl3) d: 24.6, 30.0, 34.8, 107.6,
127.0, 133.2, 139.1, 143.9, 153.2; HRMS calcd for C9H9BrNO3
(M+H)+ 257.9760, found 257.9754.
5.1.11. 4-(4-Amino-2,3,6-trimethylphenoxy)-2-isopropylphenol
(19)
To a solution of 14 (10.9 g, 27.0 mmol) in EtOAc (100 mL), 10% Pd/
C (50% wet with water, 10.5 g, 4.93 mmol) was added. The mixture
was stirred under a hydrogen atmosphere at room temperature over-
night. Insoluble materials were removed by filtration and washed
with CH2Cl2/MeOH. The filtrate was evaporated under reduced pres-
suretodrynesstogive19 (7.51 g, 97%)as a beige solid. Beige solid;mp
180–182 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3+CD3OD) d:
1.20 (6H, d, J = 6.8 Hz), 2.02 (3H, s), 2.05 (3H, s), 2.08 (3H, s), 3.20
(1H, heptet, J = 6.8 Hz), 6.23 (1H, dd, J = 3.0, 8.7 Hz), 6.52 (1H, d,
8.7 Hz), 6.73 (1H, d, J = 3.0 Hz); 13C NMR (100 MHz, CDCl3+CD3OD)
d: 13.1, 13.2, 16.4, 22.6, 27.2, 111.1, 113.1, 115.3, 115.5, 120.3,
129.2, 130.6, 136.2, 140.6, 144.4, 147.4, 152.5; HRMS calcd for
5.1.16. 2-Bromo-4-nitro-5,6,7,8-tetrahydronaphthalen-1-ol (25)
The title compound was prepared from 2322 in a manner similar
to that described for 24a as a beige solid (60%). Beige solid; mp 95–
96 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3) d: 1.70–1.90 (4H,
m), 2.70–2.80 (2H, m), 2.95–3.05 (2H, m), 6.03 (1H, s), 8.06 (1H, s);
13C NMR (100 MHz, CDCl3) d: 21.3, 21.9, 24.5, 27.2, 106.1, 126.0,
127.2, 135.2, 143.1, 153.9; HRMS calcd for C10H9BrNO3 (MꢀH)ꢀ
269.9771, found 269.9772.
5.1.17. 4-(4-Benzyloxy-3-isopropylphenoxy)-5-methyl-7-
nitroindane (26a)
C
18H24NO2 (M+H)+ 286.1802, found 286.1803.
The title compound was prepared from 24a in a manner similar
to that described for 13 as a white solid (68%). White solid; mp 86–
87 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3) d: 1.20 (6H, d,
J = 6.9 Hz), 2.05 (2H, t, J = 7.5 Hz), 2.25 (3H, s), 2.64 (2H, t,
J = 7.6 Hz), 3.30–3.50 (3H, m), 5.03 (2H, s), 6.44 (1H, dd, J = 8.8,
3.1 Hz), 6.70–6.90 (2H, m), 7.25–7.50 (5H, m), 7.96 (1H, d,
J = 0.6 Hz); 13C NMR (100 MHz, CDCl3) d: 16.1, 22.6, 24.9, 27.0,
30.4, 34.3, 70.7, 112.5, 112.7, 114.5, 125.7, 127.2, 127.8, 128.5,
130.7, 137.4, 139.3, 139.5, 141.6, 141.8, 151.1, 151.3, 154.8; HRMS
calcd for C26H28NO4 (M+H)+ 418.2013, found 418.2012.
5.1.12. N-[4-(4-Hydroxy-3-isopropylphenoxy)-2,3,5-trimethyl
phenyl]malonamic acid (20)
Ethyl N-[4-(4-hydroxy-3-isopropylphenoxy)-2,3,5-trimethylphe-
nl]malonamate was prepared from 19 in a manner similar to that
described for 16. The title compound was obtained from ethyl N-
[4-(4-hydroxy-3-isopropylphenoxy)-2,3,5-trimethylphenyl]malona-
mate in a manner similar to that described for 18as a beige solid (41%,
two steps). Beige solid; mp 95–98 °C (dec) (EtOAc–hexane); 1H NMR
(400 MHz, CDCl3+CD3OD) d: 1.19 (6H, d, J = 6.9 Hz), 2.07 (6H, s), 2.18
(3H, s), 3.24 (1H, heptet, J = 6.9 Hz), 3.49 (2H, s), 6.21 (1H, dd, J = 3.0,
8.6 Hz), 6.63 (1H, d, J = 8.6 Hz), 6.71 (1H, d, J = 3.0 Hz), 7.40 (1H, s);
13C NMR (100 MHz, CDCl3+CD3OD) d: 13.3, 14.2, 16.5, 22.5, 27.2,
40.3, 111.3, 113.3, 115.4, 124.4, 129.1, 129.4, 131.1, 131.2, 136.4,
147.8, 149.5, 151.8, 165.0, 171.4; HRMS calcd for C21H26NO5
(M+H)+ 372.1805, found 372.1806.
5.1.18. 4-(4-Benzyloxy-3-isopropylphenoxy)-5-bromo-7-
nitroindane (26b)
The title compound was prepared from 24b in a manner similar
to that described for 13 as a pale yellow solid (19%). Pale yellow so-
lid; mp 117–118 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3) d:
1.20 (6H, d, J = 6.9 Hz), 2.02–2.11 (2H, m), 2.63–2.70 (2H, m), 3.32–
3.43 (3H, m), 5.05 (2H, s), 6.49 (1H, dd, J = 3.0, 8.8 Hz), 6.78 (1H, d,
J = 8.8 Hz), 6.86 (1H, d, J = 3.0 Hz), 7.30–7.47 (5H, m), 8.34 (1H, s);
13C NMR (100 MHz, CDCl3) d: 22.6, 24.7, 27.1, 31.0, 34.4, 70.6,
112.5, 113.1, 114.7, 115.1, 127.2, 127.8, 128.1, 128.6, 137.3,
139.5, 140.7, 142.0, 143.6, 150.5, 151.8, 153.6; HRMS calcd for
5.1.13. 5-Bromoindan-4-ol (22b)
Diisopropylamine (2.55 mL, 18.1 mmol) was added to a solution
of 21 (24.2 g, 180 mmol) in CH2Cl2 (200 mL). To this solution,
N-bromosuccinimide (32.1 g, 180 mmol) was added in small portions
under ice cooling, and the mixture was stirred at room temperature
overnight. Dilute H2SO4 (pH 1, 200 mL) was added to the reaction
mixture, and the mixture was separated. The organic layer was
washed with water and brine, successively, and dried over anhydrous
MgSO4. The solvent was removed under reduced pressure. The resi-
due was purified by column chromatography on silica gel
(eluent:hexane/EtOAc = 1/0–1/1) to give 22b (31.1 g, 81%) as a white
solid. White solid; mp 66–67 °C; 1H NMR (400 MHz, CDCl3) d: 2.05–
C
25H23BrNO4 (MꢀH)ꢀ 480.0816, found 480.0817.
5.1.19. 5-(4-Benzyloxy-3-isopropylphenoxy)-6-bromo-8-nitro-
1,2,3,4-tetrahydronaphthalene (27)
The title compound was prepared from 25 in a manner similar
to that described for 13 as a beige solid (19%). Beige solid; mp 65–

3630
H. Shiohara et al. / Bioorg. Med. Chem. 20 (2012) 3622–3634
67 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3) d: 1.21 (6H, d,
J = 6.9 Hz), 1.65–1.80 (4H, m), 2.60–2.70 (2H, m), 2.90–3.00 (2H,
m), 3.36 (1H, heptet, J = 6.9 Hz), 5.02 (2H, s), 6.35 (1H, dd, J = 3.1,
8.9 Hz), 6.76 (1H, d, J = 8.9 Hz), 6.83 (6H, d, J = 3.1 Hz), 7.25–7.45
(5H, m), 8.05 (1H, s); 13C NMR (100 MHz, CDCl3) d: 21.2, 21.7,
22.6, 25.0, 26.7, 27.2, 70.6, 111.0, 112.4, 113.9, 114.8, 126.9,
127.2, 127.8, 128.5, 134.1, 136.0, 137.5, 139.6, 146.9, 150.5,
151.5, 153.6; HRMS calcd for C26H27BrNO4 (M+H)+ 498.1101, found
498.1076.
5.1.24. Ethyl N-[6-bromo-7-(4-hydroxy-3-isopropylphenoxy)
indan-4-yl]malonamate (32)
The title compound was prepared from 30 in a manner similar
to that described for 16 as a beige solid (100%). Beige solid; mp
112–114 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3) d: 1.20
(6H, d, J = 7.0 Hz), 1.34 (3H, t, J = 7.3 Hz), 2.00–2.15 (2H, m),
2.65–2.75 (2H, m), 2.80–2.95 (2H, m), 3.37 (1H, heptet,
J = 7.0 Hz), 3.50 (2H, s), 4.27 (2H, q, J = 7.3 Hz), 5.01 (2H, s), 6.46
(1H, dd, J = 3.0, 9.0 Hz), 6.75 (1H, d, J = 9.0 Hz), 6.86 (1H, d,
J = 3.0 Hz), 8.26 (1H, br s), 9.37 (1H, br s); 13C NMR (100 MHz,
CDCl3) d: 14.1, 22.6, 24.8, 27.1, 30.3, 31.0, 40.9, 62.1, 70.7, 112.2,
112.5, 114.4, 114.8, 123.5, 127.2, 127.7, 128.5, 131.1, 135.9,
137.6, 138.8, 139.1, 145.4, 151.1, 151.5, 162.7, 170.5; HRMS calcd
for C30H33BrNO5 (M+H)+ 566.1537, found 566.1540.
5.1.20. 4-(7-Amino-5-methylindan-4-yloxy)-2-isopropylphenol
(28)
The title compound was prepared from 26a in a manner similar
to that described for 19 as a beige solid (100%). Beige solid; mp
174–175 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3+CD3OD)
d: 1.19 (6H, d, J = 6.9 Hz), 1.98–2.10 (2H, m), 2.08 (3H, s), 2.62–
2.74 (4H, m), 3.22 (1H, heptet, J = 6.9 Hz), 6.33 (1H, dd, J = 3.0,
8.7 Hz), 6.43 (1H, s), 6.57 (1H, d, J = 8.7 Hz), 6.73 (1H, d,
J = 3.0 Hz); 13C NMR (100 MHz, CDCl3+CD3OD) d: 16.1, 22.6, 25.2,
27.1, 30.7, 30.8, 54.2, 112.2, 113.9, 115.4, 124.3, 128.2, 130.6,
136.6, 138.6, 139.0, 148.5, 148.7, 151.3, 165.6; HRMS calcd for
5.1.25. Ethyl N-[4-(4-benzyloxy-3-isopropylphenoxy)-3-bromo-
5,6,7,8-tetrahydronaphthalen-1-yl]malonamate (33)
The title compound was prepared from 31 in a manner similar
to that described for 16 as a white solid (64%). White solid; mp
121–122 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3) d: 1.21
(6H, d, J = 6.8 Hz), 1.34 (3H, t, J = 7.3 Hz), 1.60–1.85 (4H, m),
2.55–2.70 (4H, m), 3.37 (1H, heptet, J = 6.8 Hz), 3.52 (2H, s), 4.28
(2H, q, J = 6.8 Hz), 5.00 (2H, s), 6.38 (1H, dd, J = 3.0, 8.8 Hz), 6.74
(1H, d, J = 8.8 Hz), 6.84 (1H, d, J = 3.0 Hz), 7.25–7.50 (5H, m), 8.21
(1H, s), 9.32 (1H, br s); 13C NMR (100 MHz, CDCl3) d: 14.1, 21.7,
22.1, 22.6, 24.7, 24.7, 27.1, 41.1, 62.1, 70.6, 111.0, 112.4, 113.8,
114.6, 123.8, 127.2, 127.7, 128.5, 129.0, 133.2, 133.7, 137.7,
139.2, 146.7, 150.9, 151.4, 162.9, 170.6; HRMS calcd for
C
19H24NO2 (M+H)+ 298.1802, found 298.1805.
5.1.21. N-[7-(4-Hydroxy-3-isopropylphenoxy)-6-methylindan-
4-yl]malonamic acid (29)
The title compound was prepared from 28 in a manner similar
to that described for 20 as a white solid (80%). White solid; mp
122–125 °C (dec) (EtOH–H2O); 1H NMR (400 MHz, CDCl3 + CD3OD)
d: 1.19 (6H, d, J = 7.0 Hz), 1.95–2.10 (2H, m), 2.16 (3H, s), 2.60–2.70
(2H, m), 2.80–2.90 (2H, m), 3.22 (1H, heptet, J = 7.0 Hz), 3.48 (2H,
s), 6.33 (1H, dd, J = 3.0, 8.8 Hz), 6.59 (1H, d, J = 8.8 Hz), 6.75 (1H,
d, J = 3.0 Hz), 7.64 (1H, s); 13C NMR (100 MHz, CDCl3 + CD3OD) d:
16.1, 22.5, 25.0, 27.1, 30.3, 30.4, 40.4, 112.2, 113.8, 115.4, 122.4,
129.5, 130.0, 135.1, 136.3, 137.5, 147.2, 148.0, 151.7, 164.2,
C
31H35BrNO5 (M+H)+ 580.1693, found 580.1700.
5.1.26. N-[6-Bromo-7-(4-hydroxy-3-isopropylphenoxy)indan-4-
yl]malonamic acid (34)
Ethyl N-[6-bromo-7-(4-hydroxy-3-isopropylphenoxy)indan-4-
yl]malonamate was prepared from 32 in a manner similar to that
described for 17. The title compound was obtained from ethyl N-
[6-bromo-7-(4-hydroxy-3-isopropylphenoxy)indan-4-yl]malona-
mate in a manner similar to that described for 18 as a white solid
(32%, 2 steps). White solid; mp 182–184 °C (dec) (EtOH–H2O); 1H
NMR (400 MHz, CDCl3+CD3OD) d: 1.19 (6H, d, J = 6.8 Hz), 1.95–
2.10 (2H, m), 2.60–2.75 (2H, m), 2.80–2.90 (2H, m), 3.23 (1H, hep-
tet, J = 6.8 Hz), 3.48 (2H, s), 6.38 (1H, dd, J = 3.0, 8.7 Hz), 6.62 (1H, d,
J = 8.7 Hz), 6.77 (1H, d, J = 3.0 Hz), 8.10 (1H, s); 13C NMR (100 MHz,
CDCl3+CD3OD) d: 22.8, 25.1, 27.3, 30.7, 31.3, 40.8, 113.0, 114.5,
114.8, 115.6, 124.5, 130.9, 136.8, 137.2, 139.2, 146.2, 149.1,
171.6; HRMS calcd for
384.1801.
C
22H26NO5 (M+H)+ 384.1805, found
5.1.22. 7-(4-Benzyloxy-3-isopropylphenoxy)-6-bromoindan-4-
ylamine (30)
The title compound was prepared from 26b in a manner similar
to that described for 15 as a white solid (100%). White solid; mp
86–89 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3) d: 1.19 (6H,
d, J = 6.9 Hz), 2.00–2.10 (2H, m), 2.64–2.71 (4H, m), 3.36 (1H, hep-
tet, J = 6.9 Hz), 3.53 (2H, br s), 5.00 (2H, s), 6.45 (1H, dd, J = 3.0,
8.8 Hz), 6.75 (1H, d, J = 8.8 Hz), 6.77 (1H, s), 6.85 (1H, d,
J = 3.0 Hz), 7.27–7.46 (5H, m); 13C NMR (100 MHz, CDCl3) d: 22.7,
24.7, 27.1, 29.8, 30.9, 70.7, 111.8, 112.5, 114.1, 114.8, 117.0,
127.2, 127.7, 128.5, 130.3, 137.7, 138.9, 139.3, 140.1, 140.9,
150.8, 152.1; HRMS calcd for C25H27BrNO2 (M+H)+ 452.1220, found
452.1229.
151.1, 164.8, 171.9; HRMS calcd for
446.0609, found 446.0613.
C
21H21BrNO5 (MꢀH)ꢀ
5.1.27. N-[3-Bromo-4-(4-hydroxy-3-isopropylphenoxy)-5,6,7,8-
tetrahydronaphthalen-1-yl]malonamic acid (35)
The title compound was obtained from 33 in a manner similar
to that described for 34 as a white solid (86%). White solid; mp
124–126 °C (dec) (EtOH–H2O); 1H NMR (400 MHz, DMSO-d6) d:
1.12 (6H, d, J = 7.0 Hz), 1.55–1.75 (4H, m), 2.45–2.65 (4H, m),
3.15 (1H, heptet, J = 7.0 Hz), 3.43 (2H, s), 6.21 (1H, dd, J = 3.0,
8.8 Hz), 6.65 (6H, d, J = 8.8 Hz), 6.67 (1H, d, J = 3.3 Hz), 7.69 (1H,
s), 8.96 (1H, s), 9.51 (1H, s), 12.70 (1H, br s); 13C NMR (100 MHz,
DMSO-d6) d: 21.3, 21.4, 22.3, 24.2, 24.4, 26.5, 43.1, 110.9, 112.6,
113.0, 115.3, 125.7, 132.1, 133.1, 133.7, 135.7, 146.3, 149.1,
5.1.23. 4-(4-Benzyloxy-3-isopropylphenoxy)-3-bromo-5,6,7,8-
tetrahydronaphthalen-1-ylamine (31)
The title compound was prepared from 27 in a manner similar
to that described for 15 as a white solid (88%). White solid; mp
199–201 °C (EtOAc–hexane); 1H NMR (600 MHz, CDCl3) d: 1.20
(6H, d, J = 7.0 Hz), 1.60–1.85 (4H, m), 2.35–2.45 (2H, m), 2.50–
2.60 (2H, m), 3.36 (1H, heptet, J = 7.0 Hz), 3.55 (2H, s), 5.00 (2H,
s), 6.39 (1H, dd, J = 2.8, 8.8 Hz), 6.74 (1H, d, J = 8.8 Hz), 6.81 (1H,
s), 6.83 (1H, d, J = 2.8 Hz), 7.25–7.50 (5H, m); 13C NMR (150 MHz,
CDCl3) d: 21.9, 22.2, 22.7, 24.3, 24.7, 27.1, 70.6, 110.9, 112.4,
113.6, 114.4, 115.8, 122.8, 127.2, 127.7, 128.5, 133.6, 137.8,
139.0, 141.8, 142.3, 150.7, 152.1; HRMS calcd for C26H29BrNO2
(M+H)+ 466.1376, found 466.1371.
149.5, 164.9, 169.5; HRMS calcd for
462.0911, found 462.0896.
C
22H25BrNO5 (M+H)+
5.1.28. Ethyl N-[7-(4-hydroxy-3-isopropylphenoxy)-6-
methylindan-4-yl]oxamate (36)
Diethyl oxalate (1.35 g, 9.20 mmol) was added to 28 (274 mg,
0.920 mmol), and the mixture was stirred under an argon

H. Shiohara et al. / Bioorg. Med. Chem. 20 (2012) 3622–3634
3631
atmosphere at 110 °C for 2 h. The reaction mixture was purified by
column chromatography on silica gel (eluent: hexane/EtOAc = 19/
1–0 /1) to give 36 (318 mg, 87%) as a white solid. White solid;
mp 117–119 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3) d:
1.21 (6H, d, J = 6.9 Hz), 1.44 (3H, t, J = 7.1 Hz), 2.00–2.15 (2H, m),
2.17 (3H, s), 2.60–2.75 (2H, m), 2.80–2.95 (2H, m), 3.10–3.25 (1H,
m), 4.42 (2H, q, J = 7.1 Hz), 4.65–4.85 (1H, br s), 6.35 (1H, dd,
J = 8.6, 3.0 Hz), 6.60 (1H, d, J = 8.6 Hz), 6.76 (1H, d, J = 3.0 Hz),
7.78 (1H, s), 8.69 (1H, s); 13C NMR (100 MHz, CDCl3) d: 14.0,
16.2, 22.5, 25.0, 27.3, 30.1, 30.4, 63.7, 112.3, 113.9, 115.8, 121.8,
128.6, 130.4, 134.6, 136.0, 137.8, 147.4, 147.6, 152.0, 153.7,
adding an aqueous solution of KI (29.0 g, 175 mmol) in water
(50 mL), the reaction mixture was stirred at room temperature
for 10 min and then at 100 °C for 10 min. After adding an aqueous
solution of sodium sulfite (4 g/40 mL) under ice cooling, the
reaction mixture was extracted with EtOAc. The organic layer
was washed with water, a saturated aqueous solution of NaHCO3,
and brine, successively, and dried over anhydrous MgSO4. The sol-
vent was removed under reduced pressure to give a crude iodo
compound. The mixture of the crude product (8.89 g), Zn(CN)2
(1.45 g, 12.3 mmol), bis(dibenzylidenacetone)palladium (200 mg,
0.348 mmol),
1,10-bis(diphenylphosphino)ferrocene
(400 mg,
161.2; HRMS calcd for
398.1966.
C
23H28NO5 (M+H)+ 398.1962, found
0.721 mmol), and 1-methyl-2-pyrrolidone (30 mL) was stirred un-
der an argon atmosphere at 80 °C overnight. The mixture was par-
titioned between water and EtOAc. The organic layer was washed
with brine, dried over anhydrous MgSO4, and concentrated in va-
cuo. The residue was purified by column chromatography on silica
gel (eluent: hexane/EtOAc = 1/0–1/1) to give a crude cyano com-
pound. NaOH (9.42 g, 236 mmol) was added to a solution of the
crude product (6.69 g) in EtOH (50 mL). The reaction mixture
was refluxed under an argon atmosphere for 3 days and evapo-
rated under reduced pressure to dryness. The residue was neutral-
ized with 1 M HCl. After adding water, the mixture was extracted
with EtOAc. The organic layer was washed with brine and dried
over anhydrous MgSO4. The solvent was removed under reduced
pressure. The residue was crystallized from a small amount of
CH2Cl2 and hexane to give 40 (4.17 g, 57%) as a beige solid. Beige
solid; mp 154–155 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3)
d: 1.20 (6H, d, J = 6.9 Hz), 1.97–2.10 (2H, m), 2.22 (3H, s), 2.59–
2.68 (2H, m), 3.26–3.34 (2H, m), 3.38 (1H, heptet, J = 6.9 Hz), 5.02
(2H, s), 6.44 (1H, dd, J = 3.0, 8.8 Hz), 6.76 (1H, d, J = 8.8 Hz), 6.82
(1H, d, J = 3.0 Hz), 7.30–7.50 (5H, m), 7.86 (1H, s); 13C NMR
(100 MHz, CDCl3) d: 15.9, 22.7, 25.0, 27.0, 29.9, 34.2, 70.7, 112.3,
112.7, 114.4, 121.5, 127.2, 127.8, 128.5, 129.3, 132.6, 137.6,
137.9, 139.3, 148.7, 151.0, 151.5, 154.4, 171.3; HRMS calcd for
5.1.29. N-[7-(4-Hydroxy-3-isopropylphenoxy)-6-methylindan-
4-yl]oxamic acid (37)
The title compound was obtained from 36 in a manner similar
to that described for 18 as a white solid (86%). White solid; mp
143–144 °C (EtOH–H2O); 1H NMR (400 MHz, CDCl3) d: 1.22 (6H,
d, J = 7.0 Hz), 2.00–2.15 (2H, m), 2.20 (3H, s), 2.65–2.75 (2H, m),
2.85–2.95 (2H, m), 3.17 (1H, heptet, J = 7.0 Hz), 6.36 (1H, dd,
J = 3.0, 8.5 Hz), 6.60 (1H, d, J = 8.5 Hz), 6.76 (1H, d, J = 3.0 Hz),
7.74 (1H, s), 8.78 (1H, br s); 13C NMR (100 MHz, CDCl3) d: 16.2,
22.5, 25.0, 27.3, 30.0, 30.5, 112.4, 113.9, 115.8, 121.6, 127.7,
130.6, 135.0, 136.1, 138.1, 147.4, 148.2, 151.9, 154.6, 160.1; HRMS
calcd for C21H24NO5 (M+H)+ 370.1649, found 370.1649.
5.1.30. [7-(4-Hydroxy-3-isopropylphenoxy)-6-methylindan-4-
ylsulfamoyl]acetic acid (38)
Ethyl
[7-(4-hydroxy-3-isopropylphenoxy)-6-methylindan-4-
ylsulfamoyl]acetate was prepared from 28 and ethyl (chlorosulfo-
nyl)acetate in a manner similar to that described for 16. The title
compound was obtained from ethyl [7-(4-hydroxy-3-isopropyl-
phenoxy)-6-methylindan-4-ylsulfamoyl]acetate in a manner simi-
lar to that described for 18 as a beige solid (65%, 2 steps). Beige
solid; mp 139–143 °C (dec) (EtOH–H2O); 1H NMR (400 MHz,
CDCl3+CD3OD) d: 1.15 (6H, d, J = 6.8 Hz), 1.90-2.05 (2H, m), 2.11
(3H, s), 2.55-2.65 (2H, m), 2.85-2.95 (2H, m), 3.21 (1H, heptet,
J = 6.8 Hz), 4.00 (2H, s), 6.28 (1H, dd, J = 3.0, 8.8 Hz), 6.59 (1H, d,
J = 8.8 Hz), 6.70 (1H, d, J = 3.0 Hz), 7.11 (1H, s); 13C NMR
(100 MHz, CDCl3+CD3OD) d: 16.1, 22.6, 25.2, 27.1, 30.7, 30.8,
54.2, 112.2, 113.9, 115.4, 124.3, 128.2, 130.6, 136.6, 138.6, 139.0,
148.5, 148.7, 151.3, 165.6; HRMS calcd for C21H26NO6S (M+H)+
420.1475, found 420.1459.
C
27H29O4 (M+H)+ 417.2060, found 417.2067.
5.1.33. Ethyl {[7-(4-benzyloxy-3-isopropylphenoxy)-6-
methylindan-4-carbonyl]amino}acetate (41)
To a solution of 40 (1.15 g, 2.76 mmol) in DMF (15 mL), HOBt
(423 mg, 2.76 mmol), EDCI (795 mg, 4.14 mmol), glycine ethyl es-
ter HCl (578 mg, 4.14 mmol), and ET3N (1.15 mL, 8.28 mmol) were
added under ice cooling. The reaction mixture was stirred at room
temperature for 2 days. After adding 1 M HCl, the reaction mixture
was extracted with EtOAc. The organic layer was washed with
brine and dried over anhydrous MgSO4. The solvent was removed
under reduced pressure. The residue was purified by column chro-
matography on silica gel (eluent: hexane/EtOAc = 19/1–1/1) to give
41 (1.32 g, 95%) as a beige solid. Beige solid; mp 100–102 °C
(EtOAc–hexane); 1H NMR (600 MHz, CDCl3) d: 1.20 (6H, d,
J = 6.9 Hz), 1.33 (3H, t, J = 7.1 Hz), 1.97–2.07 (2H, m), 2.20 (3H, s),
2.58–2.66 (2H, m), 3.16–3.21 (2H, m), 3.37 (1H, heptet,
J = 6.9 Hz), 4.24 (2H, d, J = 4.9 Hz), 4.27 (2H, q, J = 7.1 Hz), 5.02
(2H, s), 6.42 (1H, dd, J = 3.0, 8.8 Hz), 6.47 (1H, t, J = 4.9 Hz), 6.75
(1H, d, J = 8.8 Hz), 6.80 (1H, d, J = 3.0 Hz), 7.30–7.46 (6H, m); 13C
NMR (150 MHz, CDCl3) d: 14.2, 15.9, 22.7, 25.5, 27.1, 29.9, 33.2,
41.9, 61.7, 70.7, 112.1, 112.7, 114.2, 127.1, 127.2, 127.7, 128.5,
129.0, 129.4, 137.6, 138.1, 139.2, 143.8, 150.9, 151.7, 152.3,
168.3, 170.3; HRMS calcd for C31H36NO5 (M+H)+ 502.2588, found
502.2597.
5.1.31. 7-(4-Benzyloxy-3-isopropylphenoxy)-6-methylindan-4-
ylamine (39)
The title compound was obtained from 26a in a manner similar
to that described for 15 as a beige solid (79%). Beige solid; mp 78–
80 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3) d: 1.19 (6H, d,
J = 6.9 Hz), 1.98–2.10 (2H, m), 2.08 (3H, s), 2.63–2.75 (4H, m),
3.36 (1H, heptet, J = 6.9 Hz), 3.45 (2H, br s), 5.00 (2H, s), 6.41 (1H,
s), 6.41 (1H, dd, J = 3.0, 8.9 Hz), 6.73 (1H, d, J = 8.9 Hz), 6.81 (1H,
d, J = 3.0 Hz), 7.27–7.45 (5H, m); 13C NMR (100 MHz, CDCl3) d:
15.9, 22.7, 25.0, 27.1, 29.7, 30.3, 70.8, 111.4, 112.6, 113.8, 115.5,
127.2, 127.7, 128.4, 128.5, 129.9, 137.7, 137.8, 138.8, 138.9,
142.3, 150.3, 152.9; HRMS calcd for C26H30NO2 (M+H)+ 388.2271,
found 388.2271.
5.1.32. 7-(4-Benzyloxy-3-isopropylphenoxy)-6-methylindan-4-
carboxylic acid (40)
5.1.34. Ethyl {[7-(4-hydroxy-3-isopropylphenoxy)-6-
Concentrated HCl (50 mL), water (100 mL), and toluene (60 mL)
were added to 39 (6.78 g, 17.5 mmol). The mixture was heated to
form a hydrochloride salt and then cooled using an ice bath. After
adding an aqueous solution of NaNO2 (1.33 g, 19.2 mmol) in water
(20 mL), the mixture was stirred under ice cooling for 5 min. After
methylindan-4-carbonyl]amino}acetate (42)
The title compound was obtained from 41 in a manner similar
to that described for 17 as a beige amorphous solid (53%). 1H
NMR (400 MHz, CDCl3) d: 1.21 (6H, d, J = 6.9 Hz), 1.32 (3H, t,
J = 7.1 Hz), 1.97–2.07 (2H, m), 2.18 (3H, s), 2.57–2.64 (2H, m),

3632
H. Shiohara et al. / Bioorg. Med. Chem. 20 (2012) 3622–3634
3.13–3.23 (3H, m), 4.24 (2H, d, J = 5.0 Hz), 4.27 (2H, q, J = 7.1 Hz),
4.98 (1H, s), 6.33 (1H, dd, J = 3.0, 8.6 Hz), 6.49 (1H, t, J = 5.0 Hz),
6.59 (1H, d, J = 8.6 Hz), 6.75 (1H, d, J = 3.0 Hz), 7.43 (1H, s); 13C
NMR (100 MHz, CDCl3) d: 14.2, 15.9, 22.5, 25.5, 27.3, 29.9, 33.2,
41.9, 61.7, 112.6, 114.0, 115.8, 127.1, 129.0, 129.4, 136.1, 138.1,
143.8, 147.5, 151.7, 152.3, 168.3, 170.3; HRMS calcd for
1.90–2.05 (2H, m), 2.20 (3H, s), 2.70–2.85 (4H, m), 5.18 (2H, br
s), 6.42 (1H, s); 13C NMR (100 MHz, CDCl3) d: 22.8, 27.2, 31.0,
40.0, 83.2, 114.0, 125.9, 138.2, 143.8, 148.3; HRMS calcd for
C
10H13IN (M+H)+ 274.0087, found 274.0091.
5.1.39. Dibenzyl(7-iodo-6-methylindan-4-yl)amine (47)
To a solution of 46 (1.70 g, 6.22 mmol) in DMF (15 mL), Cs2CO3
(4.46 g, 13.7 mmol) and benzyl bromide (1.63 mL, 13.7 mmol)
were added. The mixture was stirred at room temperature over-
night. The mixture was partitioned between water and EtOAc.
The organic layer was washed with water and brine, dried over
MgSO4, and concentrated in vacuo. The residue was crystalized
from a small amount of EtOAc and hexane to give 47 (1.16 g,
41%) as a white solid. White solid; mp 124–125 °C (EtOAc–hex-
ane); 1H NMR (600 MHz, CDCl3) d: 2.02–2.10 (2H, m), 2.29 (3H,
s), 2.89–2.94 (2H, m), 3.12–3.16 (2H, m), 4.18 (4H, s), 6.60 (1H,
s), 7.19–7.31 (10H, m); 13C NMR (150 MHz, CDCl3) d: 24.3, 28.0,
33.9, 40.1, 55.4, 91.8, 119.5, 127.0, 128.2, 128.3, 134.3, 138.5,
139.4, 147.6, 150.4; HRMS calcd for C24H25IN (M+H)+ 454.1026,
found 454.1030.
C
24H30NO5 (M+H)+ 412.2118, found 412.2125.
5.1.35. {[7-(4-Hydroxy-3-isopropylphenoxy)-6-methylindan-4-
carbonyl]amino}acetic acid (43)
The title compound was obtained from 42 in a manner similar
to that described for 18 as a white solid (79%). White solid; mp
145–147 °C (EtOAc–hexane); 1H NMR (600 MHz, DMSO-d6) d:
1.11 (6H, d, J = 7.0 Hz), 1.85–1.95 (2H, m), 2.13 (3H, s), 2.45–2.55
(2H, m), 3.00–3.10 (2H, m), 3.16 (1H, heptet, J = 7.0 Hz), 3.88 (2H,
d, J = 5.8 Hz), 6.31 (1H, dd, J = 3.0, 8.7 Hz), 6.66 (1H, d, J = 8.7 Hz),
6.67 (1H, d, J = 3.0 Hz), 7.42 (1H, s), 8.41 (1H, t, J = 5.8 Hz), 8.99
(1H, br s); 13C NMR (150 MHz, DMSO-d6) d: 15.6, 22.3, 24.9, 26.5,
29.5, 32.5, 41.1, 112.4, 113.4, 115.4, 127.6, 127.8, 128.7, 135.6,
136.8, 144.0, 149.1, 149.9, 151.4, 167.5, 171.4; HRMS calcd for
C
22H26NO5 (M+H)+ 384.1805, found 384.1808.
5.1.40. (4-Benzyloxy-3-isopropylphenyl)-(7-dibenzylamino-5-
methylindan-4-yl)methanol (48)
5.1.36. 4-Benzyloxy-3-isopropylbenzaldehyde (44)
To a solution of 6 (2.27 g, 10.0 mmol) and dichloromethyl
methyl ether (1.80 mL, 20.0 mmol) in CH2Cl2 (30 mL), TiCl4
(2.20 mL, 20.0 mmol) was added dropwise under ice cooling with
stirring. The reaction mixture was stirred at room temperature un-
der an argon atmosphere for 3.5 h. After adding ice water (300 mL),
the reaction mixture was extracted with CH2Cl2. The organic layer
was washed with a saturated aqueous solution of NaHCO3 and
brine, successively, and dried over anhydrous MgSO4. The solvent
was removed under reduced pressure. The residue was purified
by column chromatography on silica gel (eluent: hexane/
EtOAc = 1/0–1/1) to give 44 (1.75 g, 69%) as a colorless oil. 1H
NMR (600 MHz, CDCl3) d: 1.27 (6H, d, J = 6.9 Hz), 3.42 (1H, heptet,
J = 6.9 Hz), 5.18 (2H, s), 7.01 (1H, d, J = 8.4 Hz), 7.33–7.47 (5H, m),
7.69 (1H, dd, J = 2.1, 8.4 Hz), 7.80 (1H, d, J = 2.1 Hz), 9.88 (1H, s);
13C NMR (150 MHz, CDCl3) d: 22.4, 26.9, 70.2, 111.3, 127.2, 127.4,
128.2, 128.7, 129.9, 130.4, 136.4, 138.3, 161.1, 191.4; HRMS calcd
for C17H19O2 (M+H)+ 255.1380, found 255.1385.
To a solution of 47 (585 mg, 1.29 mmol) in dry THF (10 mL), a
1.48 mol/L solution of t-BuLi in n-pentane (1.30 mL, 1.89 mmol)
was added at ꢀ100 °C. The mixture was stirred for 15 min. The
solution of 44 (328 mg, 1.29 mmol) in THF (5 mL) was added.
The reaction mixture was stirred at ambient temperature for
15 min and then warmed to room temperature. After adding a sat-
urated aqueous solution of NH4Cl and brine, the mixture was ex-
tracted with EtOAc. The organic layer was dried over anhydrous
MgSO4 and concentrated in vacuo. The residue was purified by col-
umn chromatography on APS (eluent: hexane/EtOAc =19/1–1/1) to
give 48 (536 mg, 71%) as a colorless amorphous solid. 1H NMR
(400 MHz, CDCl3) d: 1.14–1.21 (6H, m), 1.90–2.05 (3H, m), 2.17
(3H, s), 2.65–2.72 (1H, m), 2.90–2.96 (3H, m), 3.34–3.43 (1H, m),
4.20 (4H, s), 5.06 (2H, s), 6.10–6.14 (1H, m), 6.53 (1H, s), 6.82
(1H, d, J = 8.5 Hz), 6.94–6.98 (1H, m), 7.15–7.45 (15H, m); 13C
NMR (100 MHz, CDCl3) d: 20.1, 22.7, 25.9, 27.0, 31.7, 32.8, 55.3,
70.1, 72.1, 111.3, 120.9, 124.2, 126.8, 127.1, 127.7, 128.2, 128.3,
128.5, 128.7, 130.8, 134.7, 135.2, 135.3, 136.9, 137.6, 138.8,
145.0, 147.0, 154.7; HRMS calcd for C41H44NO2 (M+H)+ 582.3367,
found 582.3365.
5.1.37. 4-Iodo-5-methyl-7-nitroindane (45)
To a solution of 24a (2.78 g, 14.4 mmol) and pyridine (3.15 mL,
38.9 mmol) in CH2Cl2 (20 mL), Tf2O (3.15 mL, 18.7 mmol) was
added dropwise at 0 °C. The reaction mixture was stirred at room
temperature for 25 min. After adding water and 1 M HCl, the mix-
ture was extracted with CH2Cl2. The organic layer was washed
with brine and dried over anhydrous MgSO4. The solvent was re-
moved under reduced pressure to give a crude product (4.40 g).
LiI (2.20 g, 14.5 mmol) was added to a solution of the crude prod-
uct (1.09 g, 3.35 mmol) in DMF (3 mL). The mixture was stirred un-
der an argon atmosphere at 140 °C for 14 h. After adding water, the
reaction mixture was extracted with EtOAc. The organic layer was
washed with a 1 M NaOH, water, and brine, successively, and dried
over anhydrous MgSO4. The solvent was removed under reduced
pressure to give 45 (0.949 mg, 87%, 2 steps) as a beige solid. Beige
solid; mp 115–116 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3)
d: 2.12–2.20 (2H, m), 2.51 (3H, s), 3.00–3.06 (2H, m), 3.52–3.57
(2H, m), 7.84 (1H, s); 13C NMR (100 MHz, CDCl3) d: 23.3, 27.9,
35.6, 40.3, 108.5, 122.1, 137.2, 141.3, 153.2, 168.4; HRMS calcd
for C10H11INO2 (M+H)+ 303.9829, found 303.9835.
5.1.41. 4-(7-Amino-5-methylindan-4-ylmethyl)-2-
isopropylphenol (49)
To a solution of 48 (100 mg, 0.172 mmol) in EtOH (10 mL), 2 M
HCl (1 mL) and 10% Pd/C (50% wet with water, 40 mg,
0.0188 mmol) were added. The mixture was stirred under a hydro-
gen atmosphere at 50 °C overnight. Insoluble materials were re-
moved by filtration. The filtrate was evaporated under reduced
pressure to dryness. After adding a saturated aqueous solution of
NaHCO3 and brine, the mixture was extracted with EtOAc. The or-
ganic layer was dried over anhydrous MgSO4 and concentrated in
vacuo. The residue was purified by column chromatography on sil-
ica gel (eluent: hexane/EtOAc) to give 49 (16 mg, 32%) as a white
solid. White solid; mp 160–162 °C (EtOAc–hexane); 1H NMR
(400 MHz, DMSO-d6) d: 1.12 (6H, d, J = 7.0 Hz), 1.85–2.00 (2H,
m), 2.06 (3H, s), 2.55–2.75 (4H, m), 3.16 (1H, heptet, J = 7.0 Hz),
4.52 (2H, br s), 6.27 (1H, s), 6.55 (1H, dd, J = 1.8, 8.3 Hz), 6.63
(1H, d, J = 8.3 Hz), 6.88 (1H, d, J = 1.8 Hz), 8.93 (1H, br s); 13C
NMR (100 MHz, DMSO-d6) d: 19.2, 22.5, 24.3, 26.5, 29.5, 31.9,
34.3, 114.2, 114.7, 123.1, 124.9, 125.3, 125.6, 131.2, 133.6, 134.2,
141.9, 143.6, 152.1; HRMS calcd for C20H26NO (M+H)+ 296.2009,
found 296.2003.
5.1.38. 7-Iodo-6-methylindan-4-ylamine (46)
The title compound was obtained from 45 in a manner similar
to that described for 15 as a beige solid (90%). Beige solid; mp
103–104 °C (EtOAc–hexane); 1H NMR (400 MHz, CDCl3) d:

H. Shiohara et al. / Bioorg. Med. Chem. 20 (2012) 3622–3634
3633
5.1.42. N-[7-(4-Hydroxy-3-isopropylbenzyl)-6-methylindan-4-
yl]malonamic acid (50)
mixed with appropriate concentrations of test compounds.
3,5,30-[125I]-triiodothyronine ([125I]-T3, 0.95 nM, 160 Ci/mmol,
125I]-T3(NEN) was diluted with -3,5,30-triiodothyronine (Sigma)
in a buffer containing 0.4 M KC1, 1 mM MgCl2, 10 mM Tris–HCl,
and 1 mM dithiothreitol (pH 8.0). Each 0.5 mL of the mixture was
incubated in a glass tube in an ice bath for 16–48 h. At the end
L-
The title compound was obtained from 49 in a manner similar
to that described for 20 as a white solid (93%). White solid; mp
162–165 °C (dec) (EtOH–H2O); 1H NMR (600 MHz, DMSO-d6) d:
1.11 (6H, d, J = 7.0 Hz), 1.90–2.00 (2H, m), 2.15 (3H, s), 2.75–2.85
(4H, m), 3.12 (1H, heptet, J = 7.0 Hz), 3.79 (2H, s), 6.50–6.65 (2H,
m), 6.85–6.95 (1H, m), 7.29 (1H, s), 8.98 (1H, s), 9.40 (1H, s),
12.51 (1H, br s); 13C NMR (150 MHz, DMSO-d6) d: 19.2, 22.5,
24.4, 26.4, 30.5, 31.8, 34.6, 43.2, 114.8, 122.2, 125.3, 125.8, 129.9,
131.6, 131.7, 133.2, 133.8, 134.1, 144.1, 152.3, 164.2, 169.6; HRMS
calcd for C23H28NO4 (M+H)+ 382.2013, found 382.2015.
[
L
of incubation, 500 lL of an ion-exchange resin (Muromachi Kaga-
ku, Dowex 1-X8, 80 mg/mL, suspended in the abovementioned
buffer) was added to each test tube and stirred. Stirring was re-
peated after sedimentation of the resin at the bottom of the tube,
followed by further stirring. The tubes were centrifuged at
1000 rpm for 5 min at 1 °C using a centrifuge separator (KUBOTA,
8800). A portion of the supernatant (500
other tube, and the radioactivity was measured using a
detector. The radioactivity detected reflected the quantity of
125I]-T3 bound to the soluble thyroid hormone receptor. The
amount of the recombinant thyroid hormone receptor cell homog-
enate in the experiment was used in a range in which the radioac-
tivity of T3 binding showed a concentration-dependent increase in
the amount of the homogenate.
The Kd value of T3 to the respective receptor subtype was deter-
mined according to the Scatchard analysis of the binding data ob-
tained in the various [125I]-T3 levels. The Kd values of T3 to hTRa1
and hTRb1 were 0.268 nM and 0.304 nM, respectively, under these
experimental conditions.
l
L) was transferred to an-
5.1.43. (4-Benzyloxy-3-isopropylphenyl)-(7-dibenzylamino-5-
methylindan-4-yl)methanone (51)
c-ray
Manganese (IV) oxide (2.98 g, 34.2 mmol) was added to a solution
of 48 (497 mg, 0.854 mmol) in CH2Cl2 (10 mL). The mixture was stir-
red at room temperature for 3 days. Insoluble materials were re-
moved by filtration. The filtrate was evaporated under reduced
pressure to dryness to give 51 (436 mg, 88%) as a pale yellow amor-
phous solid. 1H NMR (400 MHz, CDCl3) d: 1.24 (6H, d, J = 6.9 Hz),
1.93–2.03 (2H, m), 2.06 (3H, s), 2.59–2.67 (2H, m), 2.92–2.99 (2H,
m), 3.39 (1H, heptet, J = 6.9 Hz), 4.28 (4H, s), 5.14 (2H, s), 6.54 (1H,
s), 6.88 (1H, d, J = 8.6 Hz), 7.22–7.46 (15H, m), 7.53 (1H, dd, J = 2.1,
8.6 Hz), 7.83 (1H, d, J = 2.1 Hz); 13C NMR (100 MHz, CDCl3) d: 19.7,
22.5, 26.0, 27.0, 32.0, 32.4, 55.0, 70.1, 110.7, 119.3, 126.9, 127.1,
127.7, 128.0, 128.2, 128.3, 128.7, 129.9, 130.2, 130.9, 133.3, 133.9,
136.7, 137.6, 138.6, 143.8, 148.4, 160.2, 198.8; HRMS calcd for
[
The Ki values of each compound were calculated using the fol-
lowing equation:KiðnMÞ ¼ ½IC50ꢁ=ðl þ Kd=0:95Þ.
where IC50 represents the concentration of the compound that
inhibits [125I]-T3 binding by 50%.
C
41H42NO2 (M+H)+ 580.3210, found 580.3201.
5.1.44. (7-Amino-5-methylindan-4-yl)-(4-hydroxy-3-
isopropylphenyl)methanone (52)
5.2.2. Luciferase reporter gene assay
hTRa124 and hTRb125 were cloned into a mammalian cell expres-
sion vector (pCDM8, Promega) as described previously.26 The lucif-
erase reporter gene was constructed by inserting the thyroid
hormone responsive element (50-GATCCAGGTCATGACCTGGATCC-
30) into the commercial luciferase expression vector (pGL2-pro-
moter, Promega). Each thyroid hormone receptor vector and the
luciferase reporter vector were cotransfected into trypsin-digested
and suspended COS1 cells using the calcium phosphate-mediated
method.27 The cells were seeded into 96-well multiwell plates and
cultured overnight. On the next day, thyromimetics were added to
the culture and cultured for 1 day. Luciferase activities were mea-
sured using a commercial kit (Luciferase Assay System, Promega)
and Top count (Packard) on the third day.
To a solution of 51 (436 mg, 0.752 mmol) in THF (100 mL), 10%
Pd/C (50% wet with water, 436 mg, 0.205 mmol) was added. The
mixture was stirred under a hydrogen atmosphere at room tem-
perature overnight. Insoluble materials were removed by filtration
and washed with CH2Cl2/MeOH. The filtrate was evaporated under
reduced pressure to dryness to give 52 (136 mg, 58%) as a pale yel-
low solid. Pale yellow solid; mp 220–223 °C (THF–CH2Cl2); 1H NMR
(600 MHz, CDCl3+CD3OD) d: 1.22 (6H, d, J = 6.9 Hz), 1.97–2.05 (2H,
m), 2.10 (3H, s), 2.58–2.73 (4H, m), 3.27 (1H, heptet, J = 6.9 Hz),
6.40 (1H, s), 6.73 (1H, d, J = 8.4 Hz), 7.43 (1H, dd, J = 2.1, 8.4 Hz),
7.74 (1H, d, J = 2.1 Hz); 13C NMR (150 MHz, CDCl3+CD3OD) d:
19.6, 22.4, 25.1, 27.0, 29.0, 32.5, 114.7, 114.7, 126.4, 127.6, 128.7,
130.1, 130.3, 135.2, 135.4, 143.0, 143.7, 159.6, 199.7; HRMS calcd
for C20H24NO2 (M+H)+ 310.1802, found 310.1803.
5.2.3. Cholesterol- and T4-lowering activities
High-cholesterol diets (CE2, 1.5% cholesterol, 0.5% cholic acid,
CLEA Japan) were fed to 5-week-old male Wistar rats for 1 week
beforehand. Test compounds (3–30,000 nmol/kg) dissolved in a
vehicle containing 5% ethanol (Wako Pure Chemical) and 0.5% so-
dium carboxymethylcellulose (Wako Pure Chemical) were subcu-
taneously (5 mL/kg) administered to the rats once daily for
2 days. The rats were continuously fed the high-cholesterol diets
during the treatment. On the next day of dosing (i.e., the final
day of dosing), whole blood was collected from the abdominal aor-
ta under ether anesthesia. Serum was obtained by centrifugation of
clotted blood.
Serum cholesterol levels were determined using a commercial
kit (Cholesterol C-test Wako, Wako Pure Chemical). The mean ser-
um cholesterol level in rats fed a normal diet (CLEA Japan, CE2)
was subtracted from that in vehicle-treated rats fed a high-choles-
terol diet, and the difference was regarded to be 100%. The dosage
that lowered the serum cholesterol level by 50% is shown as ED50
in Table 3.
5.1.45. N-[7-(4-Hydroxy-3-isopropylbenzoyl)-6-methylindan-4-
yl]malonamic acid (53)
The title compound was obtained from 52 in a manner similar to
that described for 20 as a white solid (57% 2 steps). White solid; mp
162–165 °C (dec) (EtOH–H2O); 1H NMR (400 MHz, CDCl3+CD3OD)
d: 1.22 (6H, d, J = 6.9 Hz), 1.98–2.07 (2H, m), 2.15 (3H, s), 2.64–
2.69 (2H, m), 2.83–2.90 (2H, m), 3.27 (1H, heptet, J = 6.9 Hz), 3.50
(2H, s), 6.73 (1H, d, J = 8.3 Hz), 7.37 (1H, dd, J = 1.9, 8.3 Hz), 7.73
(1H, s), 7.78 (1H, d, J = 1.9 Hz); 13C NMR (100 MHz, CDCl3+CD3OD)
d: 19.3, 22.2, 24.9, 26.9, 29.6, 32.0, 40.4, 114.7, 120.6, 128.2,
129.0, 130.3, 132.1, 133.4, 133.6, 134.0, 135.7, 142.6, 160.0, 164.5,
171.5, 198.9; HRMS calcd for C23H26NO5 (M+H)+ 396.1805, found
396.1813.
5.2. Biology
5.2.1. Receptor binding assay
Recombinant hTR
a
1 and hTRb1 were expressed in insect cells.23
Serum T4 levels were determined using a commercial kit (T4 ‘Ei-
ken’, Eiken Chemical). The mean serum T4 level in rats fed a normal
Each cell homogenate containing the respective receptors was

3634
H. Shiohara et al. / Bioorg. Med. Chem. 20 (2012) 3622–3634
10. Tancevski, I.; Wehinger, A.; Demetz, E.; Hoefer, J.; Eller, P.; Huber, E.; Stanzl, U.;
Duwensee, K.; Auer, K.; Schgoer, W.; Kuhn, V.; Fievet, C.; Stellaard, F.; Rudling,
M.; Foeger, B.; Patsch, J. R.; Ritsch, A. J. Lipid Res. 2009, 50, 938.
11. Tancevski, I.; Demetz, E.; Eller, P.; Duwensee, K.; Hoefer, J.; Heim, C.; Stanzl, U.;
Wehinger, A.; Auer, K.; Karer, R.; Huber, J.; Schgoer, W.; Van Eck, M.;
Vanhoutte, J.; Fievet, C.; Stellaard, F.; Rudling, M.; Patsch, J. R.; Ritsch, A. PLoS
ONE 2010, 5, e8722.
diet (CLEA Japan, CE2) was subtracted from that in vehicle-treated
rats fed a high-cholesterol diet, and the difference was regarded to
be 100%. The dosage that lowered the serum T4 level by 30% is
shown as ED30 in Table 3.
5.3. Molecular modeling
12. Tancevski, I.; Eller, P.; Patsch, J. R.; Ritsch, A. Curr. Opin. Investig. Drugs 2009, 10,
912.
13. Friends, T. J.; Ryono, D. E.; Zhang, M. WO 2001060784.
14. Ladenson, P. W.; Kristensen, J. D.; Ridgway, E. C.; Olsson, A. G.; Carlsson, B.;
Irwin, K. I.; Baxter, J. D.; Angelin, B. N. Engl. J. Med. 2010, 362, 906.
15. Berkenstam, A.; Kristensen, J.; Mellstroem, K.; Carlsson, B.; Malm, J.; Rehnmark,
S.; Garg, N.; Andersson, C. M.; Rudling, M.; Sjoeberg, F.; Angelin, B.; Baxter, J. D.
Proc. Natl. Acad. Sci. U.S.A. 2008, 105, 663.
16. Yokoyama, N.; Walker, G. N.; Main, A. J.; Stanton, J. L.; Morrissey, M. M.;
Boehm, C.; Engle, A.; Neubert, A. D.; Wasvary, J. M.; Stephan, A. F.; Steele, R. E. J.
Med. Chem. 1995, 38, 695.
Coordinates of hTRa1 and hTRb1 were retrieved from the Protein
Data Bank (PDB); the PDB codes are 2H79 and 3GWS, respec-
tively.18 The docking model of 3 was constructed from the crystal
structure observed in the complex between hTRb1 and T3 (PDB
code: 3GWS) using Discovery Studio 3.1 (Accelrys Inc., San Diego,
CA, USA).28
17. Wagner, R. L.; Huber, B. R.; Shiau, A. K.; Kelly, A.; Cunha Lima, S. T.; Scanlan, T.
S.; Apriletti, J. W.; Baxter, J. D.; West, B. L.; Fletterick, R. J. Mol. Endocrinol. 2001,
15, 398.
Acknowledgments
18. Nascimento, A. S.; Dias, S. M. G.; Nunes, F. M.; Aparicio, R.; Ambrosio, A. L.;
Bleicher, L.; Figueira, A. C.; Santos, M. A.; Neto, M. O.; Fischer, H.; Togashi, M.;
Craievich, A. F.; Garratt, R. C.; Baxter, J. D.; Webb, P.; Polikarpov, I. J. Mol. Biol.
2006, 360, 586.
19. Filling of the unoccupied space has also studied by other group with different
ligands: GarciaCollazo, A. M.; Koehler, K. F.; Garg, N.; Färnegårdh, M.; Husman,
B.; Ye, L.; Ljunggren, J.; Mellström, K.; Sandberg, J.; Grynfarb, M.; Ahola, H.;
Malm, J. Bioorg. Med. Chem. Lett. 2006, 16, 1240.
We thank Professor Dr. Atsushi Kittaka for helpful comments
while reviewing the manuscript, and Dr. Yoshinori Nonaka and
Dr. Hideyuki Muranaka of Kissei Pharmaceutical Co., Ltd for NMR
and HRMS measurements of the compounds, respectively. We
would like to thank Enago (www.enago.jp) for the English lan-
guage review.
20. Kiso, Y.; Ukawa, K.; Nakamura, S.; Ito, K.; Akita, T. Chem. Pharm. Bull. 1980, 28,
673.
21. Dean, R. E.; Midgley, A.; White, E. N.; McNeil, D. J. Chem. Soc. 1961, 2773.
22. Beight, D. W.; Jandzinski, J. D.; Kinnick, M. D.; Lin, H.; Morin, J. M. Jr.; Richett, M.
E.; Sall, D. J.; Sawyer, J. S. WO 2002050029.
23. Miyamoto, T.; Kaneko, A.; Kakizawa, T.; Yajima, H.; Kamijo, K.; Sekine, R.;
Hiramatsu, K.; Nishii, Y.; Hashimoto, T.; Hashizume, K. J. Biol. Chem. 1997, 272,
7752.
24. Nakai, A.; Sakurai, A.; Bell, G. I.; DeGroot, L. J. Mol. Endocrinol. 1988, 2, 1087.
25. Weinberger, C.; Thompson, C. C.; Ong, E. S.; Lebo, R.; Gruol, D. J.; Evans, R. M.
Nature 1986, 324, 641.
26. Nakai, A.; Sakurai, A.; Macchia, E.; Fang, V.; DeGroot, L. J. Mol. Cell Endocrinol.
1990, 72, 143.
References and notes
1. Pramfalk, C.; Pedrelli, M.; Parini, P. Biochim. Biophys. Acta 1812, 2011, 929.
2. Moreno, M.; de Lange, P.; Lombardi, A.; Silvestri, E.; Lanni, A.; Goglia, F. Thyroid
2008, 18, 239.
3. Oetting, A.; Yen, P. M. Best Pract. Res. 2007, 21, 193.
4. Scanlan, T. S. Heart Fail Rev. 2010, 15, 177.
5. Privalsky, M. L.; Lee, S.; Hahm, J. B.; Young, B. M.; Fong, R. N. G.; Chan, I. H. J.
Biol. Chem. 2009, 284, 19554.
6. Malm, J.; Grover, G. J.; Färnegårdh, M. Mini-Rev. Med. Chem. 2007, 7, 79.
7. Grommen, S. V.; Arckens, L.; Theuwissen, T.; Darras, V. M.; De Groef, B. J.
Endocrinol. 2008, 196, 519.
27. Sambrook, J.; Fritsch, E. F.; Maniatis, T. Molecular Cloning A Laboratory Manual,
2nd ed.; Cold Spring Harbor Laboratory Press: Cold Spring Harbor, New York,
1989. Chapter 16.33.
8. Pedrelli, M.; Pramfalk, C.; Parini, P. World J. Gastroenterol. 2010, 16, 5958.
9. Erion, M. D.; Cable, E. E.; Ito, B. R.; Jiang, H.; Fujitaki, J. M.; Finn, P. D.; Zhang, B.
H.; Hou, J.; Boyer, S. H.; van Poelje, P. D.; Linemeyer, D. L. Proc. Natl. Acad. Sci.
U.S.A. 2007, 104, 15490.
28. http://accelrys.com/products/discovery-studio/.