Discovery of novel S1P2 antagonists. Part 2: Improving the profile of a series of 1,3-bis(aryloxy)benzene derivatives

Article abstract of DOI:10.1016/j.bmcl.2015.09.022

Our initial lead compound 2 was modified to improve its metabolic stability. The resulting compound 5 showed excellent metabolic stability in rat and human liver microsomes. We subsequently designed and synthesized a hybrid compound of 5 and the 1,3-bis(aryloxy) benzene derivative 1, which was previously reported by our group to be an S1P₂ antagonist. This hybridization reaction gave compound 9, which showed improved S1P₂ antagonist activity and good metabolic stability. The subsequent introduction of a carboxylic acid moiety into 9 resulted in 14, which showed potent antagonist activity towards S1P₂ with a much smaller species difference between human S1P₂ and rat S1P₂. Compound 14 also showed good metabolic stability and an improved safety profile compared with compound 9.

Full text of DOI:10.1016/j.bmcl.2015.09.022

Bioorganic & Medicinal Chemistry Letters 25 (2015) 4387–4392
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Discovery of novel S1P2 antagonists. Part 2: Improving the profile
of a series of 1,3-bis(aryloxy)benzene derivatives
b
a
a
a
Kensuke Kusumi a, , Koji Shinozaki , Yoshiyuki Yamaura , Ai Hashimoto , Haruto Kurata ,
Atsushi Naganawa a, Hideyuki Ueda c, Kazuhiro Otsuki a, Takeshi Matsushita a, Tetsuya Sekiguchi a,
Akito Kakuuchi a, Takuya Seko c
⇑
a Minase Research Institute, Ono Pharmaceutical Co., Ltd, 3-1-1 Sakurai, Shimamoto, Mishima, Osaka 618-8585, Japan
b Ono Pharma UK Ltd, MidCity Place, 71 High Holborn, London WC1V 6EA, United Kingdom
c Head Office, Ono Pharmaceutical Co., Ltd, 8-2, Kyutaromachi 1-chome, Chuo-ku, Osaka 541-8564, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 10 July 2015
Revised 21 August 2015
Accepted 8 September 2015
Available online 8 September 2015
Our initial lead compound 2 was modified to improve its metabolic stability. The resulting compound 5
showed excellent metabolic stability in rat and human liver microsomes. We subsequently designed and
synthesized a hybrid compound of 5 and the 1,3-bis(aryloxy) benzene derivative 1, which was previously
reported by our group to be an S1P2 antagonist. This hybridization reaction gave compound 9, which
showed improved S1P2 antagonist activity and good metabolic stability. The subsequent introduction
of a carboxylic acid moiety into 9 resulted in 14, which showed potent antagonist activity towards
S1P2 with a much smaller species difference between human S1P2 and rat S1P2. Compound 14 also
showed good metabolic stability and an improved safety profile compared with compound 9.
Ó 2015 Elsevier Ltd. All rights reserved.
Keywords:
Sphingosine-1-phosphate receptor 2
Antagonist
G protein-coupled receptors
Metabolic stability
Sphingosine-1-phosphate (S1P) is a membrane-derived bioac-
tive lysophospholipid that plays an important role in homeosta-
sis.1,2 S1P is present in low micromolar concentrations in plasma,
and exerts most of its biological effects through five different G
protein-coupled receptors (GPCRs), including S1P1, S1P2, S1P3,
S1P4 and S1P5.3 S1P1, S1P2 and S1P3 are widely expressed in a vari-
ety of tissues and cell types, whereas S1P4 and S1P5 are only
expressed in a limited number of tissues. All five of these receptors
are independently responsible for performing a diverse range of
biological functions.4,5
envisaged that S1P2 antagonists could become useful drugs for
the treatment of various fibrotic diseases. However, there have
been very few reports pertaining to the development of S1P2
antagonists.
We recently reported the identification of a novel series of 1,
3-bis(aryloxy)benzene derivatives as highly potent S1P2 antago-
nists, as well as some exploration of their structure–activity
relationships (SAR).11 Compound 1 (shown in Fig. 1), which is a
representative example of the compounds in this series, showed
potent antagonistic activity towards S1P2 (IC50 = 0.039
lM), as well
Subnanomolar concentrations of S1P can interact with the S1P2
receptor to elicit biological meaningful responses. S1P2 is mainly
expressed in the heart, thyroid gland, lung, trachea and liver, and
it has been suggested that this receptor is involved in a broad range
of important biological functions.5
Very few compounds have been reported in the literature to
date as ligands for S1P2, with CYM-5520 recently being reported
as a selective agonist of this receptor.6 JTE-013 is a well-known
S1P2 antagonist with an IC50 value in the range of 10–20 nM,2
and numerous studies have been conducted to evaluate the biolog-
ical properties of this compound.7–10 Based on these results, it is
as highbinding affinity (IC50 = 0.0037 M). However, the ADME
l
profile of 1 was unsuitable for its evaluation as a clinical candidate.
Based on these limitations, we temporarily switched our
attention to an alternative lead compound and conducted another
SAR study. Urea derivative 2 (shown in Table 1) was identified
following the high throughput screening (HTS) of S1P2 against
our in-house collection of 90,000 compounds. The profile of com-
pound 2 is shown in Table 1.
The details for this compound showed that there were three
issues that would need to be solved to allow for this compound
series to be developed towards a clinical candidate. The first of
these issues was the difference in the antagonistic activities of
compound 2 towards rat S1P2 (rS1P2) and human S1P2 (hS1P2),
with the compound being 24-fold more potent towards rS1P2. This
⇑
Corresponding author. Tel.: +81 75 961 1151; fax: +81 75 962 9314.
E-mail address: kusumi@ono.co.jp (K. Kusumi).
http://dx.doi.org/10.1016/j.bmcl.2015.09.022
0960-894X/Ó 2015 Elsevier Ltd. All rights reserved.

4388
K. Kusumi et al. / Bioorg. Med. Chem. Lett. 25 (2015) 4387–4392
H3C
H3C
Compound 3 showed excellent metabolic stability in the pres-
OH
Ca2+ IC50 = 0.039 µM
Binding IC50 = 0.0037 µM
logDa = 5.11
ence of rLMS (97% @ 15 min), as well as an extremely low clearance
and long half-life (CL: 0.1 ml/min/kg, T1/2: 25 h) in the rat PK study.
In contrast, the benzimidazole derivative 4 did not show enough
improved metabolic stability in the presence of rLMS (47% @
15 min) and its clearance was found to be high in rat (33 ml/
min/kg) compared with compound 2. Since compounds 3 and 4
showed close protein binding ratio (>99%), we considered that
the big difference in clearances of these two compounds would
be directly related to the difference of their in vitro metabolic
stabilities. These results therefore indicated that the alkyl chain
in compound 2 was a ‘soft-spot’ in terms of its metabolism and that
its urea moiety was not responsible for its poor metabolic stability.
Further modifications revealed that the transformation of the alkyl
chain to a phenyl ring was particularly effective for improving the
metabolic stability of these compounds and could therefore lead to
good PK profiles.
We sometimes see that high lipophilicity would correlate to
metabolic instability and/or high protein binding, and we found
that compound 3 which had the least logD value among these
compounds showed the most stable in rLMS. On the other hand,
we could not see any good correlation between lipophilicity and
protein binding, thus we considered that their protein binding
might be too high to discuss the difference.
H
N
N
O
O
F
O
NH2
O
Figure 1. Representative compound 1 from our previous report. aPredicted using
ADMET predictor (SimulationsPlus, Lancaster, CA, USA).
Table 1
Structure and profile of lead compound 212
H3C
OH
F
H3C
H
N
N
F
F
O
F
Ca2+ IC50
(
l
M)
Remaining
ratio (%) in rat
LMS, 15 min
Toxicity IC50
(lM)
logDa
hS1P2
1.7
rS1P2
0.072
Ratio
24
Human
40
Rat
9
37
4.78
We also conducted an SAR study to determine whether changes
to the 4-hydroxyl 4-phenyl piperidine moiety of compound 3
would be well tolerated. The results of this study are shown in
Table 3.
a
Predicted using ADMET predictor (SimulationsPlus, Lancaster, CA, USA).
difference in the species activity of the compound would have to
be overcome to allow for the clinical efficacy in humans to be accu-
rately estimated based on the efficacy in rat. The second issue with
compound 2 was its poor metabolic stability in rat liver micro-
somes (rLMS, with NADPH, remaining ratio = 9% at 15 min.). Com-
pound 2 also showed poor stability in human liver microsomes
(hLMS, with NADPH, remaining ratio = 40% at 15 min), and these
instabilities might suggest poor PK profile in both rat and human.
The third issue with compound 2 was its safety profile, with the
compound showing moderate levels of cellular cytotoxicity in
We initially investigated the impact of changing the bromine
atom on the left phenyl moiety to several other halogen atoms.
Although the 4-chloro derivative 5 showed similar antagonistic
activity to compound 3 (IC50 = 3.9
lM), the activity of the 4-fluoro
derivative 6 was weaker (IC50 = 9.5
l
M). Disappointingly, these
modifications had very little impact on the metabolic stability of
the compounds. Although the cytotoxicity of compound 5 was
found to be slightly less than that of 3 (IC50 = 50
lM), with com-
pound 6 being even less cytotoxic (IC50 = 69 M). Compound 5
l
was ultimately selected as the best of these compounds because
it was less toxic than 3 and showed better antagonistic activity
than 6. We also attempted to eliminate the hydroxyl group from
compound 3 to develop a better understanding of its contribution
to the activity and ADME properties of these compounds. The
replacement of the hydroxyl group in 3 with a fluoride or hydrogen
atom gave compounds 7 and 8, respectively, which did not show
any antagonist activity towards S1P2, despite the fact that they
showed excellent metabolic stability. These results therefore indi-
cate that the hydroxyl group on the piperidine moiety is essential
for the antagonistic activity of these compounds towards S1P2. We
observed the well-known relationship between lipophilicity and
toxicity among these compounds. Lower lipophilic compounds
tended to show weaker cytotoxicity. And compounds 7 and 8
which lost hydrophilic hydroxyl group showed higher logDs
(5.30 and 5.34, respectively) and relatively potent cytotoxicities
human hepatocytes (IC50 = 37 lM). To develop this series towards
a clinical candidate, it would therefore be necessary to overcome
these three issues as well as improving the potency of this series
towards S1P2 through a suitable SAR study. Although this series
of compounds showed lower potency than the 1,3-bis(aryloxy)
benzene derivatives, we thought that compound 2 was more
amenable to chemical modifications because of its low molecular
weight, and modular structure.
To improve the metabolic stability of compound 2, we ini-
tially attempted to identify the sites of its metabolism so that
we could focus our efforts towards the modification of these
sites to improve the stability. Unfortunately, however, our efforts
in this area proved to be unsuccessful because we found a large
number of oxidative metabolites in rat whole blood, which made
it difficult to identify the main site of metabolism. We subse-
quently proceeded to investigate the metabolic ‘soft-spot’ of
compound 2 using a chemical modification strategy. It was
envisaged that the alkyl chain moiety of 2 would be preferably
oxidized by cytochrome P450 enzymes to give a wide range of
oxidative metabolites. To prove this hypothesis, we synthesized
3, which had a bromophenyl moiety instead of the alkyl chain
found in compound 2 and evaluated its stability in the presence
of rLMS. This compound was also subjected to a rat pharmacoki-
netic (PK) study. Given that the urea moiety could also be a site
of metabolic instability by hydroxylation, we also synthesized
and tested the benzimidazole derivative 4 as a bioisostere of
the urea moiety. The results for these compounds are shown
in Table 2.
(IC50 = 36 and 43 lM, respectively). We considered the hydroxyl
group would be worth not only achieving the antagonistic potency
against S1P2, but also reducing lipophilicity as well as cytotoxicity.
We previously reported the development of a novel series of
highly potent S1P2 antagonists,11 and compound 1 is a representa-
tive example of the compounds belonging to this series (Table 4).
However, there were several issues associated with compound
1. Although compound 1 showed potent antagonistic activity
against hS1P2 (IC50 = 0.039 lM), this compound also experienced
similar problems to those described above for compound 2. For
example, compound 1 showed species-dependent differences in
its potency (IC50 values of 0.039 and 0.0048
lM for hS1P2 and
rS1P2), poor metabolic stability (24% in hLMS, 56% in rLMS) and

K. Kusumi et al. / Bioorg. Med. Chem. Lett. 25 (2015) 4387–4392
4389
Table 2
Metabolic stability effects
Compd
Structure
Ca2+ IC50
(lM)
Remaining ratio (%) in
rat LMS, 15 min
Rat protein
binding (%)
Rat PK clearance
(ml/min/kg)
logDb
hS1P2
1.6
rS1P2
Ratio
24
H3C
H3C
OH
F
H
N
N
F
2
0.072
9.0
97
39
4.78
F
O
F
OH
F
H
N
N
F
3
2.8
1.1
0.69
N.T.a
4.1
—
97
47
>99
>99
0.1
33
4.47
5.28
F
Br
O
F
F
H
N
HO
F
F
N
4
H3C
H3C
N
F
a
Not tested.
b
Predicted using ADMET predictor (SimulationsPlus, Lancaster, CA, USA).
Table 3
SAR around compound 3
Y
F
H
N
N
F
F
X
O
F
Compd
Substituent
Ca2+ IC50
(
lM)
Remaining ratio (%) in
LMS, 15 min
Toxicity IC50
(
lM)
logDc
X
Y
hS1P2
rS1P2
Ratio
Human
Rat
3
5
6
7
8
Br
Cl
F
Br
Br
OH
OH
OH
F
2.8
3.9
9.5
>25
>25
0.69
N.T.a
N.T.
N.T.
N.T.
4.1
88
100
97
100
100
97
77
78
100
85
38
50
69
36
43
4.47
4.40
4.10
5.30
5.34
N.C.b
N.C.
N.C.
N.C.
H
a
b
c
Not tested.
Not calculated.
Predicted using ADMET predictor (SimulationsPlus, Lancaster, CA, USA).
reasonable levels of toxicity towards human hepatocytes
(IC50 = 29 M). It was envisaged that the metabolic stability of 1
decided to focus on this position, and conducted further modifica-
tions to improve its safety profile, as well as improve the species
difference in the antagonistic activity. The results of our SAR study
around 10 are shown in Table 5.
Although the pyridine derivative 11 showed excellent meta-
bolic stability (100% in hLMS, 87% in rLMS) and a slight improve-
l
could be improved by changing its alkyl chain to a substituted phe-
nyl ring in a manner similar to that described for the same modi-
fication of 2 to 5. Based on these results, we designed and
synthesized compound 9 as a hybrid compound of compounds 1
and 5. As expected, compound 9 showed good metabolic stability
in presence of human and rat live microsomes (77% in hLMS, 85%
in rLMS) and potent antagonistic activities towards hS1P2
ment in its hepatocyte toxicity (IC50 = 49 lM), it gave a little
bigger species difference than compound 10. The introduction of
a sulfone moiety (12) had only a little impact on the species differ-
ence (8.3-fold) or the metabolic stability (73% in hLMS, 85% in
rLMS). Surprisingly, the cytotoxicity of compound 12 was very
(IC50 = 0.083 lM) and rS1P2 (IC50 = 0.013 lM). The 4-fluoro deriva-
tive 10 showed similar potency to the 4-chloro derivative 9, which
was contrary to the results observed for compounds 5 and 6. Fur-
thermore, the hybrid compounds 9 and 10 showed improved spe-
cies differences (6.4- and 4.5-fold, respectively) between rS1P2 and
hS1P2 compared with 1 (8.1-fold).
weak (IC50 > 400 lM) although the lipophilicity is higher than the
others (logD = 4.68). The sulfonamide derivative 13 provided sim-
ilar species difference (6.7-folds) and metabolic stability (72% in
hLMS, 75% in rLMS) properties to compound 10. Compound 13 also
Since we still observed relationship between lipophilicity and
cytotoxicity, we considered that further reduction of lipophilicity
would improve the safety property. Therefore we attempted to
introduce polar functional groups into compound 10 to reduce its
lipophilicity. Since the carboxamide moiety of 10 seemed to have
chances to be changed to the other polar functional groups, we
showed strong cytotoxicity towards hepatocytes (IC50 = 30 lM).
Lastly, we synthesized the carboxylic acid derivative 14, which
gave a significant decrease in the species difference (1.9-fold)
and cytotoxicity towards hepatocytes (IC50 = 124 lM) and increase
in metabolic stability in the presence of LMS (82% in hLMS, 96% in
rLMS).

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K. Kusumi et al. / Bioorg. Med. Chem. Lett. 25 (2015) 4387–4392
Table 4
Hybrid of the two previous series
H3C
H3C
OH
H
N
N
O
O
F
O
OH
NH2
H
N
N
O
O
X
O
1
F
O
NH2
O
OH
F
H
9 (X = Cl)
10 (X = F)
N
N
F
X
F
O
F
5 (X = Cl)
6 (X = F)
Compd
Ca2+ IC50
(
lM)
Remaining ratio (%) in
LMS, 15 min
Toxicity IC50
(lM)
logDc
hS1P2
rS1P2
Ratio
Human
Rat
1
5
6
9
0.039
3.9
9.5
0.083
0.076
0.0048
N.T.a
N.T.
0.013
0.017
8.1
24
100
97
77
84
56
77
78
85
86
29
50
69
34
39
5.11
4.40
4.10
5.06
4.63
N.C.b
N.C.
6.4
10
4.5
a
b
c
Not tested.
Not calculated.
Predicted using ADMET predictor (SimulationsPlus, Lancaster, CA, USA).
Table 5
Profile of the hybrid series
OH
H
N
O
N
F
O
F
O
X
Compd
X
Ca2+ IC50
Rat
(lM)
Remaining ratio (%) in
LMS, 15 min
Toxicity IC50
(
lM)
logDa
Human
0.076
0.123
0.039
Ratio
4.5
Human
Rat
86
87
85
*
NH2
10
11
12
0.017
0.014
0.0046
84
39
4.63
4.66
4.68
O
*
*
8.6
100
73
49
N
O
S
O
CH3
NH2
OH
8.3
>400
*
*
O
S
O
13
14
0.039
0.0058
0.0033
6.7
1.9
72
82
75
96
30
4.37
1.70
0.0062
124
O
a
Predicted using ADMET predictor (SimulationsPlus, Lancaster, CA, USA).

K. Kusumi et al. / Bioorg. Med. Chem. Lett. 25 (2015) 4387–4392
4391
Table 6
Additional information pertaining to the receptor selectivity
and ADME profile of compound 14 was collected, and the results
are shown in Table 6.
Profile of compound 1413
Binding assay IC50 (lM)
Compound 14 showed excellent selectivity against several
other S1P receptors (IC50 values >10 lM against S1P1, S1P3, S1P4
S1P1
>10
S1P2
0.43
S1P3
>10
S1P4
>10
S1P5
>10
and S1P5). Compound 14 also showed moderate solubility
(0.0504 mg/ml in pH 6.8 buffer) and high protein binding (human:
99.8%, rat: 99.6%). Unfortunately, however, compound 14 did not
show a sufficient improvement in rat clearance (18 ml/min/kg),
despite its good metabolic stability in the rLMS assay. The rela-
tively large clearance of the carboxylic derivative 14 was therefore
attributed to it being metabolized through some conjugation path-
way. It is noteworthy that compound 14 showed moderate Caco-2
permeability (1.3 Â 10À6 cm/s for ‘A–B’ and 1.8 Â 10À5 cm/s for
‘B–A’) with a high efflux ratio. Based on these observations, a
further optimization campaign would be needed to improve the
ADME properties of the series.
All of the urea derivatives described in this report were synthe-
sized in a similar manner. A representative example of the syn-
thetic route used for the construction of these compounds is
shown in Scheme 1 for the synthesis of 14.
Briefly, commercially available 3,5-difluoronitrobenzene (15)
was treated with Cs2CO3 and 4-fluorophenol (16) to yield
Solubility (mg/ml) in pH 6.8 buffer
Protein binding (%)
Human
99.8
Rat
0.0505
99.6
Clearance in rat PK study (ml/min/kg)
Caco-2 (Â10À6 cm/s)
A–B
B–A
18
1.3
18
Based on this result, compound 14 was identified as the best
compound of this series because it showed the smallest species
difference in terms of its potency, as well as good metabolic
stability and reduced cytotoxicity. The introduction of carboxylic
acid reduced its lipophilicity dramatically (logD = 1.70),
which suggested its better PK and safety profiles than compound
1 had.
O2N
O
O2N
F
O2N
O
HO
HO
(A)
(B)
F
+
+
F
O
F
COOMe
F
F
COOMe
19
15
16
17
18
Cl
H
N
H2N
O
Cl
Cl
O
O
OH
Cl3C
O
Cl
(C)
(D)
F
O
F
+
+
O
NH
O
O
F
COOMe
OH
COOMe
20
21
22
23
OH
H
H
N
N
O
N
O
N
O
(E)
(F)
F
F
O
F
F
O
O
14
24
COOMe
COOH
Scheme 1. Synthesis of 14. Reagents and conditions: (A) Cs2CO3, DMA, 120 °C. (B) Cs2CO3, DMA, 120 °C. (C) H2, 5% Pd/C, MeOH, rt. (D) NaHCO3, EtOAc, rt. (E) THF, reflux.
(F) 1 N NaOHaq, THF, MeOH, 40 °C.
F
F
F
F
H
N
O2N
F
H2N
H2N
N
A
B
C
F
F
F
F
F
F
F
F
S
SO3H
N
H
N
H
F
F
F
F
25
26
27
28
H3C
O
OH
H3C
H3C
OH
D
E
H3C
N
O
N
O
NH
O
O
29
30
31
F
F
F
HO
F
HO
N
N
H3C
H3C
NH
F
F
F
SO3H
H3C
H3C
N
+
N
H
N
H
F
F
28
31
4
Scheme 2. Synthesis of compound 4. Reagents and conditions: (A) NH4OH, 1,4-dioxane, rt, then H2, 5% Pd/C, EtOH, rt. (B) CSCl2, NaHCO3, CH2Cl2, H2O, rt. (C) 30% H2O2aq, 10%
NaOHaq, rt. (D) 1-Bromo-2-ethylbutane, Mg, CeCl3, THF, 0 °C to rt. (E) H2, Pd/C, EtOAc, rt. (F) Pyridine, EtOH, 150 °C microwave.

4392
K. Kusumi et al. / Bioorg. Med. Chem. Lett. 25 (2015) 4387–4392
diphenylether 17, which was subjected to a second substitution
reaction using methyl 4-hydroxylphenylcarboxylate (18) to afford
bis(aryl)ether 19. The palladium-catalyzed hydrogenation of 19
gave aniline 20, which was treated with 2,2,2-trichloroethyl
chlorocarbamate (21) and NaHCO3 to give intermediate 22. The
subsequent reaction of 22 with the commercially available
amine 23 gave the corresponding urea 24. The ester group of 24
was then hydrolyzed using aqueous NaOH to yield the target
compound 14.
Acknowledgements
The authors are deeply grateful to Dr. T. Maruyama for his many
kind and helpful suggestions during the preparation of this article.
The authors would also like to thank Mr. Y. Ochi for his many
useful comments on this article.
Supplementary data
The other compounds in Table 5 were synthesized in the same
manner with 14, using the corresponding phenol instead of 18.
The benzimidazole derivative 4 was synthesized as according to
the route shown in Scheme 2.
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2015.09.
022. These data include MOL files and InChiKeys of the most
important compounds described in this article.
Common intermediate 28 was synthesized in 3 steps from a
commercially available reagent. Briefly, 3,4-difluoro-5-nitroben-
zotrifluoride (25) was treated with NH4OH, and the resulting
product hydrogenated in the presence of a palladium catalyst to
afford di-aniline 26. Compound 26 was then cyclized using
thiophosgene (CSCl2) to afford the cyclic thiourea 27, which was
oxidized using aqueous H2O2 to give sulfonic acid 28. The other
intermediate 31, which was also used for the synthesis of
compounds 1 and 11, was synthesized in 2 steps from the commer-
cially available N-protected piperidone 29. Briefly, compound 29
was treated with CeCl3 and 2-ethylbutane-1-yl magnesium
bromide to yield alcohol 30, which was subjected to a palladium-
catalyzed hydrogenation to afford 31. The subsequent reaction of
28 with 31 gave 4.
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Commun. 2002, 299, 483.
8. Sanchez, T.; Skoura, A.; Wu, M. T.; Casserly, B.; Harrington, E. O.; Hla, T.
Arterioscler. Thromb. Vasc. Biol. 2007, 27, 1312.
9. Salomone, S.; Potts, E. M.; Tyndall, S.; Ip, P. C.; Chun, J.; Brinkmann, V.; Waeber,
C. Br. J. Pharmacol. 2008, 153, 140.
10. Fiorentina Roviezzo; Vincenzo Brancaleone; Luana De Gruttola; Valentina
Vellecco; Mariarosaria Bucci; Bruno D’Agostino; Dianne Cooper; Raffaella
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830.
Compound 2 and its derivatives in Table 3 were synthesized
from the corresponding amine and 5-fluoro-3-trifluoro methyl
benzene isocyanate.
In summary, we have discovered
a potent and selective
S1P2 antagonist without species differences. The chemical mod-
ification of lead compound 2 provided the metabolically stable
phenylpiperidine derivative 3, which was combined with a bis
(aryl)ether derivative to give the potent and metabolically
stable S1P2 antagonist 9. Further exploration of this compound
led to the introduction of carboxylic acid moiety to give 14,
which showed improved species difference and safety profile
characteristics, as well as a high level of antagonist activity.
Given that there are still some ADME profile issues associated
with 14 (i.e., low permeability, high protein binding), further
work towards the optimization of this series is currently
underway in our laboratory and will be reported in due
course.
11. Kusumi, K.; Shinozaki, K.; Kanaji, T.; Kurata, H.; Naganawa, A.; Otsuki, K.;
Matsushita, T.; Sekiguchi, T.; Kakuuchi, A.; Seko, T. Bioorg. Med. Chem. Lett.
2015, 25, 1479.
12. Spectra data of 2 are shown below: 1H NMR (300 MHz, CDCl3) d ppm 0.87 (t,
J = 7.50 Hz, 6H) 1.06 (s, 1H) 1.38 (m, 7H) 1.64 (m, 4H) 3.34 (m, 2H) 3.84 (m, 2H)
6.59 (s, 1H) 6.96 (d, J = 8.00 Hz, 1H) 7.31 (s, 1H) 7.56 (m, 1H), 13C NMR d ppm
162.87, 153.863, 141.71, 132.47, 123.28, 111.56, 109.89, 106.66, 70.29, 46.89,
40.60, 37.14, 35.49, 27.41, 10.88.MASS: (ESI, Pos.) 781 (2M+H)+, 391 (M+H)+.
13. Spectra data of 14 are shown below: 1H NMR (300 MHz, DMSO-d6) d ppm 8.63
(s, 1H), 7.95 (d, 2H), 7.48 (dd, 2H), 7.24 (t, 2H), 7.15–7.07 (m, 7H), 7.02 (dd, 1H),
6.31 (dd, 1H), 5.13 (s, 1H), 3.98–3.93 (m, 2H), 3.1–3.10 (m, 2H), 1.84–1.77 (m,
2H), 1.59–1.54 (m, 2H). 13C NMR d ppm 166.66, 161.80, 160.84, 160.37, 158.55,
158.40, 156.44, 154.17, 151.97, 145.60, 143.59, 131.57, 126.73, 125.61, 121.19,
117.74, 116.57, 114.41, 104.53, 103.95, 102.43, 69.65, 40.00, 37.73 MASS: (FAB,
Pos.) 561 (M+H)+.