Synthesis and structure-activity relationship of novel RXR antagonists: Orally active anti-diabetic and anti-obesity agents

Article abstract of DOI:10.1016/j.bmcl.2007.06.080

A series of diazepinylbenzoic acid derivatives were synthesized and tested in the inhibition assay of the transactivation of RXR. Oral treatment of cyano derivatives (16f) was found to show anti-diabetic and anti-obesity effects in KK-A^y mice.

Full text of DOI:10.1016/j.bmcl.2007.06.080

Bioorganic & Medicinal Chemistry Letters 17 (2007) 4804–4807
Synthesis and structure–activity relationship of novel RXR
antagonists: Orally active anti-diabetic and anti-obesity agents
Junichi Sakaki, Masashi Kishida,* Kazuhide Konishi, Hiroki Gunji, Atsushi Toyao,
Yuki Matsumoto, Takanori Kanazawa, Hidefumi Uchiyama, Hiroaki Fukaya,
Hironobu Mitani, Yoshie Arai and Masaaki Kimura
Novartis Institute for Biomedical Research, Tsukuba Research Institute, Ohkubo 8, Tsukuba-shi, Ibaraki 300-2611, Japan
Received 4 April 2007; revised 15 June 2007; accepted 18 June 2007
Available online 30 June 2007
Abstract—A series of diazepinylbenzoic acid derivatives were synthesized and tested in the inhibition assay of the transactivation of
RXR. Oral treatment of cyano derivatives (16f) was found to show anti-diabetic and anti-obesity effects in KK-Ay mice.
Ó 2007 Elsevier Ltd. All rights reserved.
The retinoid X receptor (RXR) belongs to the superfam-
ily of intracellular nuclear receptors. RXR is known to
N
O
N
regulate gene transcription and control cellular differen-
tiation and proliferation through the formation of het-
erodimers with other nuclear receptors, such as RAR,
TR, VDR, NGFIB, LXR, FXR, and PPARs.1–3 There-
fore, RXR modulators are of potential use in disease
indications, for instance, diabetes, obesity, dermatologic
diseases, inflammatory diseases, and proliferative
diseases.4,5
O
S
NO2
N
H
N
N
CF3
HO
1
2
O
HO
O
Figure 1. Diazepinylbenzoic acic analogues.
In the preceding paper,6 we reported the synthesis, SAR,
and pharmacokinetic study of the RXR antagonists 2
based on the diazepinylbenzoic acid scaffold 1 (Fig. 1).7,8
ical yields. Sulfonamides 8 were readily synthesized
by the direct sulfonylation with chlorosulfonic acid
followed by the treatment with SOCl2 and then
amines.
We herein describe a further modification of the diazepi-
nylbenzoic acid structure and results of in vivo study in
KK-Ay mice.
Hydroxy-diazepinylbenzoic esters 12 were served as pre-
cursors for phenoxy derivatives 13 and a triflate 14,
which was transformed into acetyl analogues 15 by the
known palladium coupling.9,11 Cyano derivatives 16
were prepared from bromo-tetrahydronaphthalene 10
and commercially available 4-amino-3-nitro-benzonitri-
le by slight modification of the reported procedures
(Scheme 2).7,8,10,11
Followed by the reported procedures,7,8 the unsubsti-
tuted diazepinylbenzoic acid 3 and its bromide 4 were
prepared as shown in Scheme 1. These two com-
pounds can be utilized as a versatile intermediate to
deliver a variety of diazepinylbenzoic acid analogues.
The bromide 4 was subjected to the palladium-cata-
lyzed coupling reaction with thiols and amines to
give sulfide 5 and aniline 9 derivatives in good chem-
Preparation of 3-fluoro- (21) or 2-fluoro-terephthalic
acid 4-methyl ester (26) was carried out as shown in
Scheme 3.11 Bromination of 18 afforded a mixture of
di- and tri-bromides both of which were converted to
the target 21 without separation. The same bromination
Keywords: RXR; Antagonist; Anti-diabetic; Anti-obesity.
*
Corresponding author. Tel.: +81 29 865 2306; fax: +81 29 865
2308; e-mail: masashi.kishida@novartis.com
0960-894X/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2007.06.080

J. Sakaki et al. / Bioorg. Med. Chem. Lett. 17 (2007) 4804–4807
4805
N
N
R1
R1
N
N
Br
S
S
c
a
b
N
N
N
N
O
O
O
O
3
4
5
6
O
O
OH
O
d,c
e,c
f,c
R2
R1
N
N
R2'
N
N
S
O
N
S
O
R3
O
O
N
N
N
O
O
O
7
8
9
OH
OH
OH
Scheme 1. Reagents: (a) Br2, Fe, CCl4 or Py–HBr3, 0CH2Cl2; (b) R1SH, Pd(PPh3)4, NaOt-Bu, toluene; (c) 2 M NaOH, DMF; (d) m-CPBA CH2Cl2;
(e) i—ClSO3H, CCl4; ii—SOCl2, DMF; iii—R2R2 NH, pyridine, CH2Cl2; (f) amine, Pd2(dba)3, 2-(di-tert-butylphosphino)biphenyl, NaOt-Bu,
toluene.
4
R
N
4
4
R
N
R
N
5
Br
R
O
a
OH
b,c
O
N
N
X
N
ref. 7,8,10
10
X
Y
O
Y
O
O
O
ref. 10, 11
11
12
13
O
OH
d
4
R
4
4
R
N
R
N
N
CN
Tf
O
O
N
X
N
X
e,c
N
X
Y
O
16
Y
O
OH
Y
O
O
OH
15
14
Scheme 2. Reagents: (a) BBr3, CH2Cl2; (b) R5Cl (or Br), NaH, DMF; (c) 2 M NaOH, DMF; (d) Tf2O, pyridine, CH2Cl2; (e) butyl vinyl ether,
Pd(OAc)2, dppf, Et3N, DMF, H2O.
F
O
F
O
F
O
O
F
O
F
O
O
O
c
d
b
O
O
a
b
O
OH
OH
H
Br
HO
HO
18
O
Br
20
19
O
F
17
21
26
O
O
O
O
F
F
F
OH
e
d
O
F
a
OH
Br
H
H
Br
O
O
O
22
25
23
24
Scheme 3. Reagents: (a) MeI, K2CO3, MeCN; (b) NBS, cat.BPO, CCl4; (c) AgNO3, t-BuOH, H2O; (d) NaClO2, H2NSO3H, MeCN, H2O; (e)
AgNO3, EtOH, H2O
using NBS was initially applied to the methyl ester of 22,
however the reaction took a few days for completion.
However, direct bromination of the acid 22 turned out
to proceed more smoothly. The synthetic method for
21 and 26 is applicable to a hundred gram scale prepa-
ration (Table 2).

4806
J. Sakaki et al. / Bioorg. Med. Chem. Lett. 17 (2007) 4804–4807
Table 2. Inhibition of the transactivation of RXRa with diazepinyl-
benzoic acid derivatives (15–16)
These derivatives prepared were tested in the inhibition
assay10 of the transactivation activity for RXRa
homodimer (Tables 1 and 2). In general, the diazepinyl-
benzoic acid analogues possessing an electron-with-
drawing group (7, 8, 15, and 16) showed a higher
antagonistic activity than the ones having an electron-
donating group (6, 9, and 13). The comparison between
sulfides and sulfones bearing a same substituent (e.g., 6b
vs 7c or 6e vs 7f) gave the same result. The effect of fluo-
rine introduction to the phenyl group was examined for
acetyl 15 and cyano 16 derivatives. Both 2- and 3-fluo-
rine substitutions were found to generally decrease the
antagonistic activity to some extent, however the 3-fluo-
rination was more tolerable than the 2-fluorination in
both cases of the acetyl and cyano derivatives (15d
and 16f).
Compound R4
X, Y LGa IC50 (lM) 9-RAb IC50 (lM)
15a
15b
15c
15d
15e
Me
Et
H, H 1.1
H, H 0.97
F, H 4.6
H, F 1.7
F, H 3.3
0.89
0.79
—
Me
Me
Et
1.1
3.0
16a
16b
16c
16d
16e
16f
Me
Et
H, H 0.82
H, H 0.48
0.43
0.32
2.1
n-Pr H, H 2.1
Me
Et
H, F 1.2
F, H 1.1
H, F 0.77
0.52
0.53
0.50
Et
Values are means of three independent experiments measured in
duplicate.
a LG100268.
b 9-cis-retinoic acid.
Table 1. Inhibition of the transactivation of RXRa with diazepinyl-
benzoic acid derivatives (6–9, 13)
Ameliorative effects of 16f on KK-Ay mice fed a high-fat
diet were investigated. Male 8-week-old KK-Ay mice
prefed a high-fat diet (32% safflower oil) for 9 days were
treated with 16f (0.01 and 0.03%) as a food admixture
for 14 days. Treatment with 16f resulted in a decrease
in body weight gain. Total food intake was not signifi-
cantly changed in the treated groups. Plasma glucose
and insulin concentrations were decreased following
treatment with the compound as shown in Figure 2.
Compound
6, 7: R1
8: R2, R2
9: R3
LGa IC50
9-RAb IC50
0
(lM)
(lM)
13: R5
6a
6b
6c
6d
6e
Me
3.0
1.6
1.0
1.6
4.9
2.0
4-MeO–Phenyl
4-CF3O–Phenyl
4-Cl–Benzyl
0.72
0.39
0.67
5.5
4-MeO–Benzyl
A series of diazepinylbenzoic acid derivatives were de-
signed and synthesized by employing the versatile inter-
mediates 4 and 12. A simple preparation method of 2- or
3-fluoroterephthalic acid half ester was also developed.
The method can be utilized for a hundred gram scale
7a
7b
7c
7d
7e
7f
Me
n-Pr
1.7
1.4
0.92
0.36
0.24
0.95
1.4
0.45
0.17
0.13
0.42
0.78
4-MeO–Phenyl
4-CF3O-Phenyl
4-Cl–Benzyl
4-MeO–Benzyl
8a
8b
8c
8d
8e
8f
Me, H
Me, Me
n-Bu, H
1.3
2.2
1.3
2.0
20
15
10
5
70
60
50
40
30
20
10
0
a
b
0.41
0.96
1.0
0.19
0.46
0.45
0.45
1.0
4-CF3O–Phenyl, H
Pyrrolidinyl
Morpholinyl
N-Methylpiperazinyl
1.0
1.9
**
8g
0
-5
9a
9b
O
N-Me
7.0
11
3.9
—
**
-10
-15
13a
13b
13c
13d
13e
13f
13g
13h
13i
Me
Et
3.6
5.4
4.2
3.0
Control
0.01%
0.03%
Control
0.01%
0.03%
n-Pr
i-Pr
5.9
6.8
3.7
4.0
20
15
10
5
800
600
400
200
0
d
c
CF3
3-F-n-Pr
7.0
4.3
5.0
3.8
**
2-Morpholinyl–Et
4-F-Benzyl
4-Cl-Benzyl
4-CF3-Benzyl
Cl–Py–Mec
4-CHF2O-Benzyl
Morpholinyl–Bzd
1.6
1.2
*
0.64
1.4
0.34
0.58
1.2
**
13j
2.7
**
13k
13l
0.55
0.85
0.84
0.29
0.68
0.85
0
Control
0.01%
0.03%
Control
0.01%
0.03%
13m
Values are means of three independent experiments measured in
duplicate.
Figure 2. Ameliorative effects of compound 16f in obese/diabetic KK-
Ay mice fed a high-fat diet ((a) total body weight change, (b) total food
intake, (c) plasma glucose concentration, (d) plasma insulin concen-
a LG100268.
b 9-cis-retinoic acid.
c 5-Cl-Pyridine-3-yl-methyl.
d 4-N-Me-Morpholinyl-benzyl.
*
tration). Values are means SEM for 8 animals per group. P < 0.05,
**P < 0.01, significant difference from the control group (one-way
ANOVA with Dunnett’s multiple comparison tests).

J. Sakaki et al. / Bioorg. Med. Chem. Lett. 17 (2007) 4804–4807
4807
5. Gernert, D. L.; Neel, D. A.; Boehm, M. F.; Leibowitz, M.
D.; Mais, D. A.; Michellys, P. Y.; Rungta, D.; Reifel-
Miller, A.; Grese, T. A. Bioorg. Med. Chem. Lett. 2004, 14,
2759.
6. Sakaki, J.; Konishi, K.; Kishida, M.; Gunji, H.; Kanaz-
awa, T.; Uchiyama, H.; Fukaya, H.; Mitani, H.; Kimura,
M. Bioorg. Med. Chem. Lett., in press.
7. Ebisawa, M.; Umemiya, H.; Ohta, K.; Fukasawa, H.;
Kawachi, E.; Christoffel, G.; Gronemeyer, H.; Tsuji, M.;
Hashimoto, Y.; Shudo, K.; Kagechika, H. Chem. Pharm.
Bull. 1999, 47, 1778.
preparation. A functional group on the diazepinyl ring
of the antagonists synthesized (6–9, 13, and 15–16)
was found to effect on the RXR antagonistic activity.
The cyano derivative (16f) was evaluated as food admix-
ture in the KK-Ay mice model. The compound was
found to decrease a body weight gain without changing
food intake and also decrease both glucose and insulin
levels, demonstrating its potential for anti-diabetic and
anti-obesity agent.
8. Umemiya, H.; Fukasawa, H.; Ebisawa, M.; Eyrolles, L.;
Kawachi, E.; Eisenmann, G.; Gronemeyer, H.; Hashim-
oto, Y.; Shudo, K.; Kagechika, H. J. Med. Chem. 1997,
40, 4222.
Acknowledgments
We thank Messrs. Junichi Yamanaka and Toshiyuki
Kurihara and Ms. Toshie Kurasawa for synthetic sup-
port. We thank Mses. Serina Nakano and Akiko Kato
for technical support of the reporter gene assay.
9. See Ref. 6 and references cited therein.
10. Synthesis of compound 16f: To a solution of 4-(2-cyano-5-
ethyl-7,7,10,10-tetramethyl-7,8,9,10-tetrahydro-5H-5,13-
diazabenzo[4,5]-cyclohepta[1,2-b]naphthalene-12-yl)-2-flu-
orobenzoic acid methyl ester (5.36 g, 10.5 mmol) in DMF
(100 ml) and THF (100 ml) was added 2 N NaOH (50 ml,
0.10 mol) at room temperature. The reaction mixture was
stirred at the same temperature for 2 h. The mixture was
acidified with 1 N HCl, diluted with H2O, and extracted
with ether. The organic layer was washed with H2O twice,
dried over MgSO4, and evaporated in vacuo. The resulting
solid was washed with hexane/ether (1:1) and dried to give
References and notes
1. Sporn, M. B.; Roberts, M. B.; Goodman, A. B. In The
Retinoids; Academic: Orlando, 1984.
2. Mangelsdorf, D. J.; Umesono, K.; Evans, R. M. In The
Retinoids: Biology, Chemistry, and Medicine, 2nd ed.;
Raven: New York, 1994; p 319.
3. Schulman, I. G.; Crombie, D.; Bissonnette, R. P.; Cesario,
R.; Roegner, K.; Shao, G.; Heyman, R. A. In Handbook of
Experimental Phamacology; Springer: Berlin, 1999; vol.
139, p 215.
1
16f (4.02 g, 88%) as a yellow solid. H NMR (400 MHz,
DMSO-d6) d: 0.99 (3H, s), 1.07 (3H, t), 1.09 (3H, s), 1.19
(3H, t), 1.22 (3H, s), 1.51–1.58 (4H, m), 3.56–3.66 (1H, m),
3.74–3.82 (1H, m), 6.92 (1H, s), 7.02 (1H, s), 7.17 (1H, d),
7.45 (1H, dd), 7.59–7.65 (3H, m), 7.92 (1H, dd), 13.46 (1H,
br).
11. For experimental details, see: Sakaki, J; Konishi, K;
Kishida, M; Kimura, M; Uchiyiama, H; Mitani, H;
WO2004/089916.
4. Gardinier, K. M.; Gernert, D. L.; Grese, T. A.; Neel, D.
A.; Mapes, C. M.; Michellys, P.-Y.; Boehm, M. F.; WO02/
071827 A2, 2002.