The discovery of potent selective NPY Y2 antagonists

Article abstract of DOI:10.1016/j.bmcl.2013.05.038

A series of small molecules with a piperidinyl core were synthesized and tested for binding affinity (IC₅₀) at human Neuropeptide Y Y ₂ receptor. Various amide related analogs (ureas, reversed amides, and sulfonamides) were evaluated

Full text of DOI:10.1016/j.bmcl.2013.05.038

Bioorganic & Medicinal Chemistry Letters 23 (2013) 4141–4144
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
The discovery of potent selective NPY Y2 antagonists
⇑
Wenying Chai , Victoria D. Wong, Diane Nepomuceno, Pascal Bonaventure, Timothy W. Lovenberg,
Nicholas I. Carruthers
Janssen Research & Development LLC, 3210 Merryfield Row, San Diego, CA 92121, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 20 February 2013
Revised 6 May 2013
Accepted 13 May 2013
Available online 22 May 2013
A series of small molecules with a piperidinyl core were synthesized and tested for binding affinity (IC50
)
at human Neuropeptide Y Y2 receptor. Various amide related analogs (ureas, reversed amides, and sulfon-
amides) were evaluated. Several potent and selective NPY Y2 antagonists were identified.
Ó 2013 Elsevier Ltd. All rights reserved.
Keywords:
NPY Y2
NPY Y2 antagonists
Neuropeptide Y (NPY) is 36-amino acid peptide discovered in
the early 1980s. It is widely distributed in the central and periph-
eral nervous systems.1 To date, five NPY receptors (Y1, Y2, Y4, Y5, y6)
were identified. The Y2 receptor is the predominant NPY receptor
in the brain which can also be found in the periphery. The Y2 recep-
tor has been implicated in many physiological functions including
bone formation, gastrointestinal motility, and food intake.2,3 Iden-
tification of novel Y2 receptor ligands will allow for further elucida-
tion of the physiological role of the Y2 receptor.4–7
NO2
F
F
NH
a
+
CN
2
3
NO2
F
NO2
F
N
NPY is the natural NPY Y2 agonist. Several small molecule
antagonists have been reported in the literature in recent years.8–15
Some of them were described from our research lab.14,15
N
b
5
OH
O
CN
4
O
NH2
F
NH
e, f
c, d
N
N
N
N
N
F
6, R1 = NHEt
7, R2 = NEt2
R1
O
O
H
N
R2
F
1, JNJ 31020028
NPY Y2 IC50 = 6 nM
MTP IC50 = 710 nM
O
N
8, R1 = NHEt
9, R1 = NEt2
R1
O
Scheme 1. Reagents and conditions: (a) K2CO3, DMF, 16 h, 95%; (b) 48% HBr, reflux,
90%; (c) (COCl)2, DMF, CH2Cl2; (d) NH2Et or NHEt2, NEt3, CH2Cl2; (c, d) 75–81%; (e)
SnCl2ꢀ2H2O, EtOH/EtOAc; (f) R2 COCl, NEt3, CH2Cl2; e to f: 38-72%.
⇑
Corresponding author. Tel.: +1 8587843047.
E-mail address: wchai@its.jnj.com (W. Chai).
0960-894X/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2013.05.038

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W. Chai et al. / Bioorg. Med. Chem. Lett. 23 (2013) 4141–4144
Table 1
Table 2
Amides
Ureas
H
N
H
N
R2
NHR3
F
F
O
O
N
N
8, R1 = NHEt
9, R1 = NEt2
10, R1= NHEt
11, R1= NEt2
R1
R1
O
O
R3
NPY Y2 IC50 (nM)18
No.
R2
NPY Y2 IC50 (nM)18
No.
8a
12
4
10a
27
7
10b
10c
162 18
8b
8c
24 11
70 50
N
H3C
H3C
CH3
N
O
O
CH3
15
12
2
6
S
N
CH3
11a
H3C
8d
8e
665 135
476 116
Br
N
O
O
CH3
H3C
boxylic acid 5 (90%). Acid chloride formation followed by treat-
ment with ethyl amine or diethyl amine yielded amides 6 and 7
(75–81%). Nitro reduction of 6 or 7 with SnCl2ꢀ2H2O in EtOH/EtOAc
followed by amide formation with various acid chlorides providing
the diamides 8 and 9 (38–72%) (Scheme 1).
9a
9b
7
1
N
N
The di-amides (Table 1) with biaryl groups at the right hand
side 8a–8c show good human binding affinity at NPY Y2 (IC50
12–70 nM). The bromo intermediate 8d also showed some affinity
(IC50 665 nM). 3,5-Dimethyl oxazole 8e was evaluated and
:
CH3
37 23
H3C
:
showed affinity at NPY Y2 (IC50: 476 nM). Compounds with diethyl
amides at the left hand side (9a, 9b) show much better binding
affinity (IC50: 7–37 nM) compared to their mono-ethyl amide ana-
logs (8b, 8d).
On the right hand side, urea analogs (Table 2) were prepared.
Ureas were obtained through reacting 6 or 7 with different isocya-
nates (Scheme 2).
The urea with a biphenyl group at the right hand side (10a)
demonstrated good binding affinity at NPY Y2 (IC50: 27 nM). Di-
methyl oxazoles 10c and 11a exhibited slightly improved affinity
(IC50: 12–16 nM) (see Scheme 3).
In addition to amides and ureas, the reversed amide was inves-
tigated. The reverse amide was prepared from two fragments (15
and 18). Compound 12, benzyl protected 2-phenyl-2-(piperidin-
4-yl)acetonitrile was hydrolyzed with 48% HBr providing 13 in
good yield (100%). The carboxylic acid 13 reacted with ethylamine,
HATU in DMF yielding amide 14 (76%). De-protection of 14
through hydrogenation provided the piperidine fragment 15
(100%). The other fragment bromide 18 was obtained from the
amide formation with the acid 16 and the amine 17 (90%). The
two fragments (15 and 18) were coupled through Pd catalyzed
amination yielding the reversed amide 19 (IC50: 45 nM)
Sulfonamide analog 20 was prepared from 6 and (1,10-biphe-
nyl)-2-sulfonyl chloride (Scheme 4). However, 20 shows no affinity
at NPY Y2 receptor.
In order to identify selective, brain-penetrant, non-peptidic NPY
Y2 antagonists, a pharmacophore directed screen of our compound
collection was initiated. Compound 1 was identified and reported
in 2010.14,15 The original lead from HTS was prepared for a micro-
somal triglyceride transfer protein (MTP) program.16,17 Inhibiting
MTP prevent the assembly of apo B-containing lipoproteins thus
inhibiting the synthesis of chylomicrons and VLDL and leading to
decrease in plasma levels of LDL-C. Thus, obtaining good selectivity
over MTP was one of the goals for this project. Here we report a
series of compounds related to 1, with a piperidine core, as NPY
Y2 antagonists. Throughout the study, we identified potent NPY
Y2 compounds maintaining good MTP selectivity, and/or improved
microsomal stability. We also identified peripherally restricted
compounds. SAR and preliminary in vivo data for selected com-
pounds are presented.
Our efforts focused on the right hand side biaryl amide portion.
Ureas, reversed amide and sulfonamide analogs were evaluated.
These compounds were synthesized and tested for NPY Y2 binding
affinity at the human receptor.18 Chemistry started from 2-phenyl-
2-(piperidin-4-yl)acetonitrile 2 reacting with 3,4-difluoro-nitro-
benzne 3, and K2CO3 in DMF. Amino replacement with fluorine
was successful providing 4 in very good yield (95%). Hydrolysis
of the cyano group with 48% HBr provided the corresponding car-

W. Chai et al. / Bioorg. Med. Chem. Lett. 23 (2013) 4141–4144
4143
Since compounds 8a, 8b, 8c, 9a, 9b, 10a, 10c, 11a, and 19 show
good NPY Y2 binding affinity, their selectivity over MTP was tested
using an enzymatic assay.16,17 The results were summarized in Ta-
ble 3. Amide 9b and ureas 10a, 10c, 11a show good selectivity over
MTP. Phenyl-pyridine and dimethyl oxazole moieties help improv-
ing the selectivity. Urea linkage also favors Y2 over MTP. The selec-
tive compounds were evaluated in NPY Y2 functional assay13 and
Cl
S
+
6
O
O
H
N
F
S
O
O
F
NH2
N
N
20
O
NH
6, R1 = NHEt
7, R1 = NEt2
O
R1
Scheme 4. Reagents and conditions NEt3, CH2Cl2; 70%.
H
N
F
NR3
Table 3
Selectivity over MTP
O
N
No.
MTP IC50 (nM)16,17
13
210 10
NPY Y2 IC50 (nM)18
12
24 11
70 50
<300
10, R1 = NHEt
11, R1 = NEt2
8a
8b
8c
9a
4
4
O
R1
25
7
5
1
Scheme 2. Reagents and conditions: R3NCO, NEt3, CH2Cl2 (60–85%).
9b
>10,000
7400
>10,000
>10,000
37 23
10a
10c
11a
19
27
15
12
7
2
6
33
2
45 15
N
Ph
b
N
N
Ph
a
COOH
13
CN
12
Table 4
Microsomal stability (remaining after 15 min in human and rat)
No.
Microsomal stability (Hu)
Microsomal stability (Rat)
Ph
NH
1
1.4% Rmn
73% Rmn
5.3% Rmn
1.5% Rmn
1.7% Rmn
98% Rmn
3.3% Rmn
17% Rmn
c
9a
9b
11a
O
NH
O
NH
15
14
behaved as antagonists (9b: pA2 = 7.5; 10c: pA2 = 8.4; 11a:
pA2 = 8.7).
O
F
COOH
H2N
Amides and ureas with piperidinyl core show improved micro-
somal stability (Table 4). Amide 9a with piperidinyl core exhibits
much better microsomal stability (human: 73% remaining after
15 min; rat: 98% remaining after 15 min) comparing to 1 (human:
1.4% remaining after 15 min; rat 1.7% remaining after 15 min),
however it is less selective over MTP. Amide 9b and urea 11a with
piperidinyl core also show improved microsomal stability (human:
5.3–1.5% remaining after 15 min; rat: 3.3–17% remaining after
15 min) comparing to 1. However they are less stable than com-
pound 9a. Both 9b and 11a has great selectivity over MTP.
Due to still less favorable microsomal stability, further in vivo
evaluations of 9b and 11a were limited and performed through
subcutaneous administration. After subcutaneous administration
in rat, 9b crossed the blood brain barrier and occupied NPY Y2
receptors (approximately 50% at 10 mg/Kg, experiments were per-
formed according to the procedure described in Ref. 13). However,
ureas 10c and 11a showed no brain penetration and consequently
no NPY Y2 receptor occupancy.
F
d
N
H
+
Br
Br
16
17
18
e
15
18
+
O
F
N
H
N
19
O
NH
In summary, a series of compounds with a piperidinyl core were
evaluated for NPY Y2 antagonism. Different amides and amide ana-
logs were investigated. We identified new heterocyles: dimethyl
oxazoles showing excellent selectivity over MTP (9b, 10c, 11a). Ur-
eas show good selectivity over MTP comparing amides and reverse
Scheme 3. Reagents and conditions: (a) 48% HBr, 105 °C, 100%; (b) H2NEt, HATU,
DMF, 16 °C, 76%; (c) 10%Pd/C, EtOH, 16 °C, 100%; (d) NEt3, HATU, DMF, 16 °C, 90%;
(e) Pd2(dba)3, X-Phos, NaOtBu, PhCH3, 100 °C, 16 h, 18%.

4144
W. Chai et al. / Bioorg. Med. Chem. Lett. 23 (2013) 4141–4144
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microsomal stability. These new finding certainly will help us to
design better NPY Y2 antagonists in the future. Potent and selective
ureas 10c and 11a showed no brain penetration, and thus they are
potentially useful tool compounds to help understand the roles of
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