Synthesis and biological evaluation of 5-nitropyrimidine analogs with azabicyclic substituents as GPR119 agonists

Article abstract of DOI:10.1016/j.bmcl.2012.12.011

5-Nitropyrimidine analogs substituted with conformationally restricted azabicyclic amines and alcohols were prepared and evaluated their agonistic activity against human GPR119. The analogs bearing endo-azabicyclic amines and alcohols (7, 8, 11, and 12) e

Full text of DOI:10.1016/j.bmcl.2012.12.011

Bioorganic & Medicinal Chemistry Letters 23 (2013) 1519–1521
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis and biological evaluation of 5-nitropyrimidine analogs
with azabicyclic substituents as GPR119 agonists
Zunhua Yang a,b, Yuanying Fang a, Tuan-Anh N. Pham a, Jongkook Lee a, Haeil Park a,
⇑
a College of Pharmacy of Kangwon National University, Chuncheon 200-701, Republic of Korea
b College of Pharmacy, Jiangxi University of Traditional Chinese Medicine, Nanchang 330004, China
a r t i c l e i n f o
a b s t r a c t
Article history:
5-Nitropyrimidine analogs substituted with conformationally restricted azabicyclic amines and alcohols
were prepared and evaluated their agonistic activity against human GPR119. The analogs bearing endo-
azabicyclic amines and alcohols (7, 8, 11, and 12) exhibited full agonistic activities while the analogs with
exo-azabicyclic amines and alcohols were proved as partial agonists (9, 10, 13, and 14) regardless of their
EC50 values. 5-Nitropyrimidine analogs with (2-fluoro-4-methylsulfonyl)phenylamino group (8, 10, 12,
14) showed more potent GPR119 activation activities than the analogs without fluorine in all cases (7,
9, 11, 13).
Received 29 October 2012
Revised 4 December 2012
Accepted 8 December 2012
Available online 20 December 2012
Keywords:
GPR119 agonist
Type 2 diabetes
5-Nitropyrimidines
Azabicyclic alcohols
Azabicyclic amines
Ó 2012 Elsevier Ltd. All rights reserved.
Type
2
diabetes is
a
complex metabolic disorder and is
aromatic heterocycles were found in the structures of GPR119 ago-
nists under development (Fig. 1).6–11 Also piperidine scaffold was
attached to the diverse aromatic heterocycles in most cases. These
results implied that piperidine scaffold plays an important role for
bioactivity. Also 2-fluoro-4-methanesulfonylamine fragment is
very common in the structures of developing GPR119 agonists as
shown in the structures of APD-668 and AR-231453.
In our efforts to discover pharmacologically superior GPR119
agonists, pyrimidine derivative AR-231453 was chosen as a lead
structure and planned to replace the piperidine ring to the
conformationally restricted azabicyclic ring to produce new pyrim-
idine analogs (Fig. 2). One of our strategies included the incorpora-
tion of ethylene to conformationally constrain the piperidine ring,
one of the more common motifs found in GPR119 agonist struc-
tures. It was suggested from a precedent literature that the piper-
idine carbamate region seemed to make pharmacologically very
important H-bond with the receptor.12 Therefore, it is surmised
that sterical changes in this region cause significant pharmacolog-
ical changes. Herein we report synthesis of 5-nitropyrimidine ana-
logs with conformation restricted azabicyclic amines/alcohols as
GPR119 agonists for the treatment of type 2 diabetes.
characterized by a high blood glucose level that caused by insulin
resistance or insufficient insulin secretion, accounting for approxi-
mately 90% of all cases of diabetes.1 Although the number of pa-
tients with type
2 diabetes that successfully achieve target
glucose levels is steadily improving, a substantial number of sub-
jects continue to fall short of acceptable treatment goals, leaving
them at high risk of development of diabetes-associated complica-
tions such as hypoglycemia, weight gain, bone fractures, etc.1–3
Therefore, new drugs with novel mode of action that exhibit im-
proved efficacy and safety relative to current available medications
are clearly needed.
GPR119 is a G-protein coupled receptor predominantly ex-
pressed on pancreatic beta cells and intestinal enteroendocrine
cells. GPR119 agonists such as oleoylethanolamine (OEA), lyso-
phosphatidylcholine, N-oleoyldopamin and olvanil were reported
to stimulate glucose-dependent insulin secretion in vitro and low-
er elevated blood glucose level in vivo. Furthermore, it was demon-
strated that they stimulated the release of the incretin (GLP-1 and
GIP).4–6 Therefore, GPR119 agonist has emerged as a promising tar-
get for the treatment of type 2 diabetes and obesity by improving
glucose homoeostasis while concurrently slowing gastric empty-
ing, reducing food intake and promoting weight loss.4–6
5-Nitropyrimidine analogs were prepared from key intermedi-
ates 1 and 2 following the procedures and conditions as shown
in Scheme 1. Reaction of 4,6-dichloropyrimidine13 with 4-(methyl-
thio)aniline or 2-fluoro-4-(methylthio)aniline14 in DMF followed
by oxidation with mCPBA afforded compounds 1 and 2 in 58%
and 56%, respectively. Coupling reactions of the intermediates (1,
Recently, efforts have been made toward development of anti-
diabetic agents for type 2 diabetes targeting GPR119. Diverse fused
⇑
Corresponding author. Tel.: +82 33 250 6920; fax: +82 33 255 7865.
E-mail address: haeilp@kangwon.ac.kr (H. Park).
2) and endo-azabicyclic amine
3 with diisopropylethylamine
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.12.011

1520
Z. Yang et al. / Bioorg. Med. Chem. Lett. 23 (2013) 1519–1521
O
O
O
N
N
N
N
O
N
N
O
H CO S
3
2
O
N
N
O
N
F
APD-668
PSN-632408
N
N
O
N
N
2
N
H CO S
NH
NO
3
2
F
AR-231453
Figure 1. Structures of selected GPR119 agonists under clinical development.
H3CO2S
N
N
O
H3CO2S
N
N
N
H
N
H
O
N
O
N
N
N
H
N
H
R
NO2
O
R
NO2
exo compounds (R = H,F)
endo compounds (R = H,F)
H3CO2S
H3CO2S
N
N
N
N
N
H
O
O
N
N
H
O
O
R
NO2
R
NO2
O
O
endo compounds (R = H,F)
exo compounds (R = H,F)
Figure 2. Structures of target GPR119 agonists.
N
H3CO2S
N
Cl
N
N
O
H3CO2S
N
N
Cl
NO2
N
H
N
H
O
N
O
N
R-NH2 (3 or 4)
N
N
H
R
NO2
1. Ar-NH2, DMF
2. mCPBA, DCM
H
O
R
NO2
9 R = H
DIPEA, THF
N
7 R = H
8
R = F
N
Cl
10
R = F
H3CO2S
NH NO2
H3CO2S
H3CO2S
N
N
N
N
R
1
R-OH (5 or 6)
R = H
N
O
O
N
H
O
O
N
2 R = F
H
LiHMDS, THF
N
R
NO2
R
NO2
O
O
11
13
R = H
R = H
12 R = F
14 R = F
O
O
O
HO
O
N
N
N
N
O
O
O
H2N
O
OH
NH2
4
5
3
6
Scheme 1. Synthetic pathways for target GPR119 agonists.
(DIPEA) in THF yielded products (7, 8) in 81% and 89%, respectively.
Reactions of the intermediates (1, 2) and exo-azabicyclic amine 4
with diisopropylethylamine (DIPEA) in THF yielded products (8,
9) in 83% and 80%, respectively. Coupling reactions of the interme-
diates (1, 2) and endo-azabicyclic alcohol 5 with lithium hexameth-
yldisilazide (LiHMDS) in THF yielded products (11, 12) in 68% and
65%, respectively. Also coupling reactions of the intermediates (1,
2) and exo-azabicyclic alcohol 6 yielded products (13, 14) in 71%
and 75%, respectively. Azabicyclic amines (3 and 4) and alcohols
(5 and 6) were prepared following known methods in literatures.15

Z. Yang et al. / Bioorg. Med. Chem. Lett. 23 (2013) 1519–1521
1521
Table 1
agonistic activities while analogs with exo-azabicycle moiety
showed partial agonistic activities. Our present results are com-
pletely in accordance with those from a precedent paper.12 These
preliminary results encourage us to search diverse conformation
restricted azabicyclic motifs and also heteocycle rings as congeners
of pyrimidine ring. The follow-up studies and results will be re-
ported in due course.
In vitro GPR119 agonistic activities of 5-nitropyrimidine analogs (7–14)
O
N
N
n
N
X
O
H3CO2S
NH
NO2
R
(R = H,F; X = O,N ; n = 0,1)
Acknowledgements
Compound
R
X
n
hGPR119 activity
The authors thank to Dr. Moon Ho Son (Dong-A Pharm. Co. Ltd.)
for hGPR119 cAMP reporter assay. The authors also thank to
Pharmacal Research Institute and Central laboratory of Kangwon
National University for the use of bioassay facilities and analytical
instruments.
a
EC50 (nM)
% Maxb
7
8
9
10
11
12
13
14
OEA
H
F
H
F
H
F
H
F
N
N
N
N
O
O
O
O
0
0
1
1
0
0
0
0
11.5
1.5
139
99
>10,000
6.7
41
53
4.9
1.5
14.5
1.4
99
116
69
References and notes
65
1. Schmeltz, L.; Metzger, B. In Williams, M., Ed., 2nd ed.; Comprehensive
Medicinal Chemistry; Elsevier: Oxford, 2007; Vol. 6, pp 417–458.
2. Drucker, D. J.; Sherman, S. I.; Gorelick, F. S.; Bergenstal, R. M.; Sherwin, R. S.;
Buse, J. B. Diabetes Care 2010, 33, 428.
2200
100
a
Concentration for 50% cAMP stimulation of OEA.
cAMP stimulation % compared to maximal effect of OEA.
b
3. Ahren, B. Nat. Rev. Drug Disc. 2009, 8, 369.
4. Overton, H. A.; Babbs, A. J.; Doel, S. M.; Fyfe, M. C. T.; Gardner, L. S.; Griffin, G.;
Jackson, H. C.; Procter, M. J.; Rasamison, C. M.; Tang-Christensen, M.;
Widdowson, P. S.; Williams, G. M.; Reynet, C. Cell Metab. 2006, 3, 167.
5. Overton, H. A.; Fyfe, M. C. T.; Reynet, C. Br. J. Pharmacol. 2008, 153, S76.
6. Jones, R. M.; Leonard, J. N. Annu. Rep. Med. Chem. 2009, 44, 149.
7. Hansen, H. S.; Rosenkilde, M. M.; Holst, J. J.; Schwartz, T. W. Trends Pharmacol.
Sci. 2012, 33, 374.
8. Semple, G.; Fioravanti, B.; Pereira, G.; Calderon, I.; Uy, J.; Choi, K.; Xiong, Y.; Ren,
A.; Morgan, M.; Dave, V.; Thomsen, W.; Unett, D. J.; Xing, C.; Bossie, S.; Carroll,
C.; Chu, Z.; Grottick, A. J.; Hauser, E. K.; Leonard, J.; Jones, R. M. J. Med. Chem.
2008, 51, 5172.
9. Wu, Y.; Kuntz, J. D.; Carpenter, A. J.; Fang, J.; Sauls, H. R.; Gomez, D. J.; Ammala,
C.; Xu, Y.; Hart, S.; Tadepalli, S. Bioorg. Med. Chem. Lett. 2010, 20, 2577.
10. Xia, Y.; Chackalamannil, S.; Greenlee, W. J.; Jayne, C.; Neustadt, B.; Stamford, A.;
Vaccaro, H.; Xu, X.; Baker, H.; O’Neill, K.; Woods, M.; Hawes, B.; Kowalski, T.
Bioorg. Med. Chem. Lett. 2011, 21, 3290.
11. Semple, G.; Ren, A.; Fioravanti, B.; Pereira, G.; Calderon, I.; Choi, K.; Xiong, Y.;
Shin, Y. J.; Gharbaoui, T.; Sage, C. R.; Morgan, M.; Xing, C.; Chu, Z. L.; Leonard, J.
N.; Grottick, A. J.; Al-Shamma, H.; Liang, Y.; Demarest, K. T.; Jones, R. M. Bioorg.
Med. Chem. Lett. 2011, 21, 3134.
Compounds 7–14 were evaluated their abilities to activate the
human GPR119 receptor in a cell-based cAMP assay and, which
were expressed in EC50 and % max values. The EC50 values repre-
sent the concentration of the tested compounds for 50% cAMP of
oleylethanolamine (OEA), while the % max values present the rel-
ative response (%) of the tested compounds compared to the max-
imal effect of OEA.16
As shown in Table 1, most 5-nitropyrimidine analogs possessing
azabicyclic amines/alcohols exhibited more potent GPR119 agonis-
tic activity than OEA, however, some analogs were identified as
partial agonists (9, 10, 13, 14). All the 5-nitropyrimidine analogs
with (2-fluoro-4-methylsulfonyl)phenylamino group (10, 12, 14)
showed more potent GPR119 activation activities than the analogs
with 4-(methylsulfonyl)phenylamino group (9, 11, 13). One of very
interesting phenomena was observed that the analogs (7, 8, 11, 12)
with endo-azabicyclic amine (3) and alcohol (5) were proved as full
agonists while the analogs (9, 10, 13, 14) with exo-azabicyclic
amine (4) and alcohol (6) were proved as partial agonists regard-
less of their EC50 values. It may be caused that the analogs with
endo-azabicyclic amine or alcohol are constrained to the agonist
conformation and are full agonists.12
In summary, in the present article, we have reported the syn-
thesis of eight 5-nitropyrimidine analogs possessing conformation-
ally restricted azabicyclic amines and alcohols and biological
evaluation of their abilities to activate the human GPR119 receptor
in a cell-based cAMP assay, which are expressed in EC50 and % max
values. The analog 7 exhibited maximum agonistic activity (139%
max) with slightly weak EC50 value (11.5 nM) while the analog
12 exhibited quite good agonistic activity (116% max) with strong
EC50 value (1.5 nM). Our present results also revealed that analogs
with fluorine substituted phenylamino group showed more potent
receptor agonistic activity than analogs without fluorine in all
cases and analogs with endo-azabicycle moiety showed full
12. McClure, K. F.; Darout, E.; Guimarães, C. R.; DeNinno, M. P.; Mascitti, V.;
Munchhof, M. J.; Robinson, R. P.; Kohrt, J.; Harris, A. R.; Moore, D. E.; Li, B.;
Samp, L.; Lefker, B. A.; Futatsugi, K.; Kung, D.; Bonin, P. D.; Cornelius, P.; Wang,
R.; Salter, E.; Hornby, S.; Kalgutkar, A. S.; Chen, Y. J. Med. Chem. 1948, 2011, 54.
13. Latli, B.; Jones, P. J.; Krishnamurthy, D.; Senanayake, C. H. J. Labelled Compd.
Radiopharm. 2008, 51, 54.
14. Zhu, W.; Ma, D. J. Org. Chem. 2005, 70, 2696.
15. For preparation of azabicyclic amines 3 and 4 see: (a) Berdini, V.; Cesta, M. C.;
Curti, R.; D’Anniballe, G.; Bello, N. D.; Nano, G.; Nicolini, L.; Topai, A.; Allegretti,
M. Tetrahedron 2002, 58, 5669; (b) Kazmierski, W. M.; Aquino, C.; Chauder, B.
A.; Deanda, F.; Ferris, R.; Jones-Hertzog, D. K.; Kenakin, T.; Koble, C. S.; Watson,
C.; Wheelan, P.; Yang, H.; Youngman, M. J. Med. Chem. 2008, 51, 6538; For
preparation of azabicyclic alcohols 5 and 6 see: (c) Nagase, T.; Takahashi, T.;
Sasaki, T.; Nagumo, A.; Shimamura, K.; Miyamoto, Y.; Kitazawa, H.; Kanesaka,
M.; Yoshimoto, R.; Aragane, K.; Tokita, S.; Sato, N. J. Med. Chem. 2009, 52, 4111.
16. Human GPR119 cAMP reporter assay: HEK293 cells (4 Â 103 cells/well) were
seeded on 96 half-well plates and incubated for 24 h. The cells were transected
with GPR119 expression plasmid (OriGene Technologies, Inc., USA) using
Lipofectamine and Plus reagent (Life Technologies Corporation., USA). After
24 h, transfected cells were incubated with compounds dissolved in assay
buffer (KRBH buffer containing 0.1% BSA and 500 lM 3-isobutyl-1-
methylxanthine) for 60 min at 37 °C. Subsequently, cells were harvested
with lysis buffer (50 mM phosphate buffer containing 1 M KF and 1.25% Triton
X-100, pH 7.0) for 10 min at room temperature and the assay was performed
using the cAMP homogeneous time-resolved fluorescence kit (CIS bio
international, France).