Differentially functionalized diamines as novel ligands for the NPY 2 receptor

Article abstract of DOI:10.1016/S0960-894X(03)00554-7

The synthesis of novel ligands for the NPY₂ receptor using solid phase split pool methodology is described. One of the analogues, diamine 16, was found to be a potent NPY₂ binder.

Full text of DOI:10.1016/S0960-894X(03)00554-7

Bioorganic & Medicinal Chemistry Letters 13 (2003) 2883–2885
Differentially Functionalized Diamines as Novel Ligands for
the NPY2 Receptor
Charles J. Andres,a Ildiko Antal Zimanyi,b,* Milind S. Deshpande,c Lawrence G. Iben,a
Katharine Grant-Young,a,* Gail K. Mattsona and Weixu Zhaia
aBristol-Myers Squibb Pharmaceutical Research Institute, 5 Research Parkway, Wallingford, CT 06492, USA
bBristol-Myers Squibb Pharmaceutical Research Institute, Pennington-Rocky Hill Road, Hopewell, NJ 08525, USA
cAchillion Pharmaceuticals Inc., 300 George Street, New Haven, CT 06511, USA
Received 17 March 2003; revised 20 May 2003; accepted 2 June 2003
Abstract—The synthesis of novel ligands for the NPY2 receptor using solid phase split pool methodology is described. One of the
analogues, diamine 16, was found to be a potent NPY2 binder.
# 2003 Elsevier Ltd. All rights reserved.
Neuropeptide Y (NPY) is a 36 amino acid peptide that
is widely distributed in the central nervous system. This
neuropeptide activates a family of 6 NPY receptors, 5 of
which have been cloned.1 The Y2 receptor is the pre-
dominant NPY receptor in the brain and can also be
found in the periphery (i.e., the intestine, kidneys, sexual
organs, etc.). The Y2 receptor has been implicated in a
variety of physiological functions, such as kidney func-
tions,2 bone formation,3 gastrointestinal motility, food
intake, regulation of glucose and cholesterol homeostasis
in type 2 diabetes, cardiovascular regulation, neuronal
excitability,4 anxiety,5 learning and memory, pain,6 and
migraine.7 Identification of novel Y2 receptor ligands is
necessary for the elucidation of the physiological role of
the Y2 receptor. Our early search for a novel ligand for
the NPY2 receptor, via high-throughput screening, lead
to diamine 10. Its structural simplicity and suitability for
combinatorial synthesis made these diamines attractive
hits. The present paper describes the synthesis of acy-
lated diamines and their affinity for binding to the
NPY2 receptor. Uriac employed a solid phase approach
to the synthesis of nonsymmetrical polyamines.8 After
due consideration, we chose as our starting point the
polymer bound acyl imidazole as described by Hauske9
(Scheme 1). Wang10 resin 1 was treated with carbo-
nyldiimidazole (CDI) to give the activated resin 2. Dis-
placement of the imidazole with an amino alcohol at
60 ꢀC followed by oxidation yielded yielded resin bound
aldehyde 3.11 Reductive amination with substituted
anilines gave amino carbamate 4. Acylation of polymer
bound diamine 4 with various acid chlorides afforded
intermediate 5. Intermediate 5 could then be cleaved
from solid support by trifluoroacetic acid. Post cleavage
reductive amination yielded the tertiary amines 6. Yields
for the synthesis, including the post-solid support
reductive amination step, averaged 30%.
Initial SAR12 (vide infra) lead to the need to further
examine diversity at R2. Thus, ortho-iodo resin 7 was
treated with various aryl zinc bromides to afford cou-
pled intermediate 8 using standard conditions as shown
in Scheme 2.12 Resin cleavage and reductive amination
afforded tertiary amines 9.
The first area of interest was the replacement of the
cinnamic acid moiety at R1, which was thought to be a
potential metabolic liability (Table 1).
Both the benzothiophene (compound 12) and the trans-
cyclopropyl phenyl group (compound 11) proved to be
good cinnamic acid surrogates. Gratifyingly, the ben-
zothiophene group also increased potency by one order
of magnitude. It is worthy of mention that other cin-
namic acid surrogates such as the benzofuran, (com-
pound 13) were employed, but the resulting analogues
showed poor binding affinity.
Next, we focused our attention on the length of the
diamine linker R2 (Table 2).
*Corresponding author. Tel.:+1-203-677-6186; fax:+1-203-677-6984;
e-mail: katherine.grantyoung@bms.com
0960-894X/03/$ - see front matter # 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0960-894X(03)00554-7

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C. J. Andres et al. / Bioorg. Med. Chem. Lett. 13 (2003) 2883–2885
Scheme 1. Solid phase diamine synthesis.
Scheme 2. Negishi cross-coupling on solid support.
Two, three, and four carbon linked diamines were syn-
thesized, with the best potency arising from the three
carbon spacer (compound 16). Other linkers, including
linkers cyclized on the terminal amine, failed to generate
stronger binding potencies. Lastly, we searched for a
suitable replacement for the 2-benzylsulfanyl aniline
because sulfur was viewed as a potential oxidative lia-
bility. We examined a wide range of commercially
available and structurally diverse anilines (Table 3).
Those compounds containing meta and para substitu-
tion failed to show Y2 receptor binding activity. This
left us to analogue at only the ortho position on the
aniline ring. Formation of carbon-carbon bonds at the
ortho position, by employing Negishi couplings,13 led to
analogue 21, the most potent compound in the series.
In summary, functionalized diamines were efficiently
synthesized and shown to be ligands for the NPY2
receptor. This work illustrates for the first time that a
small molecule is capable of displacing NPY and bind-
ing to the NPY2 receptor. In vivo biological studies of
Testing of numerous analogues quickly revealed the
importance of the aniline substitution pattern at R3.

C. J. Andres et al. / Bioorg. Med. Chem. Lett. 13 (2003) 2883–2885
2885
Table 1.
Table 3.
Compd
R2
1000
Compd
R1
IC50 (nM)
20
450
10
10,000
21
>10,000
>10,000
>10,000
>10,000
2200
11
12
13
14
15
3700
22
1000
23
>10,000
24
1000
25
>10,000
Sperk, G.; Hokfelt, T.; Herzog, H. Proc. Atl. Acad. Sci. U.S.A
2002, 99, 8938.
4. Naveilhan, P.; Svensson, L.; Nystron, S.; Ekstrand, A. J.;
Ernfors, P. Peptides 2002, 23, 1087.
Table 2.
5. Munglani, R.; Hudspith, M. J.; Hunt, S. P. Drugs 1996, 52,
371.
6. Nakajima, M.; Inui, A.; Asakawa, A.; Momose, K.; Ueno,
N.; Teranishi, A.; Baba, S.; Kasuga, M. Peptides 1998, 19, 359.
7. Edvinsson, L.; Goadsby, P. J. Cephalalgia 1994, 14, 320.
8. Tomasi, S.; Le Roch, M.; Renault, J.; Corbel, J. C.; Uriac,
P.; Carboni, B.; Moncoq, D.; Martin, B.; Delcros, J. G. Bio.
Med. Chem. Lett. 1998, 8, 635.
Compd
n
R3
IC50 (nM)
9. Hauske, J. R.; Dorff, P. Tetrahedron Lett. 1995, 36, 1589.
10. Wang, S. S. J. Am. Chem. Soc. 1973, 95, 1328.
11. Rotella, D. P. J. Am. Chem. Soc. 1996, 118, 12246.
12. Test compounds in five concentrations (0.001, 0.01, 0.1, 1
and 10 mM) were assayed in Laboratory Automation System
(Biomek 2000 from Beckman). Experiments were carried out
in the following buffer: 50 mM Tris pH7.4, 1 mM MgCl, 2.5
mM CaCl2, 145 mM NaCl, 0.1% BSA, 10 mg/mL Leupeptin
and 10 mg/mL Aprotinin. The assay was conducted as follows:
each reaction consisted of 25 mL compound, 25 mL [125I]PYY
(0.05 nM final conc., NEN Du-Pont) and 200 mL SMS-KAN
cell membranes endogenously expressing NPY Y2 receptor (8
mg/reaction). After incubating at 25 ꢀC for 1 h, assay plates
were filtered through 1% PEI pre-soaked (>2 h) GF/C filters
and then washed with ice cold Tris buffer (50mM pH7.4) 5Â1
mL. The samples were put in sample plate and 200 mL Opti-
Phase ‘SuperMix’ (Wallac) was added to each well. The sam-
ples were soaked for 10 h before counting in 1450 Microbeta
Plus Liquid Scintillation Counter (Wallac). IC50’s were deter-
mined by non-linear regression using Excel Fit program.
13. Knochel, P. A.; Rottlander, M. Tetrahedron Lett. 1997,
38, 1749.
16
17
18
19
2
3
4
3
Me
Me
Me
H
>10,000
1000
>10,000
>10,000
these compounds will be the subject of a future
communication.
References and Notes
1. Antal Zimanyi, I.; Fathi, Z.; Poindexter, G. S. Cur. Pharm.
Des. 1998, 4, 229.
2. Bischoff, A.; Michel, M. Pflugers Arch. 1998, 435, 443.
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R. F.; Thomas, G. P.; Gardiner, E. M.; Herzog, H. J. Clin.
Invest. 2002, 109, 915. 4. Sainsbury, A.; Schwarzer, C.; Cou-
zens, M.; Fetissov, S.; Furtinger, S.; Jenkins, A.; Cox, H. M.;