Synthesis and biological evaluation of a 6-aminofuro[3,2- c ]Pyridin-3(2H)-one series of GPR 119 agonists

Article abstract of DOI:10.1055/s-0032-1323760

G protein-coupled receptor 119 (GPCR 119 (GPR119)) agonists have received considerable attention as a promising therapeutic option for treatment of type 2 diabetes mellitus. GPR119 is one of the GPCRs expressed in pancreatic islet β-cells and its activation enhances stimulation of insulin secretion in a glucose-dependent manner. We have recently described a series of 6-amino-1H-indan-1-ones as potent, selective, and orally bioavailable GPR119 agonists with an amino group that plays important roles not only in their drug-like properties, such as high aqueous solubility, but also in their potent agonistic activity. However, many of these compounds displayed strong to moderate inhibition of human ether-a?-go-go related gene channel. Attenuation of the basicity of the amino group by replacing the adjacent benzene ring with electron-deficient heteroaromatic rings provided several heterocyclic cores among which 6-aminofuro[3,2-c]pyridin-3(2H)-one was selected as a promising scaffold. Further optimization around the side chain moiety led to the discovery of 17i, which showed not only strong human GPR119 agonistic activity (EC⁵⁰=14nM), but also beneficial effects on gastric emptying and plasma total glucagon-like peptide-1 levels in mice. Georg Thieme Verlag KG Stuttgart New York.

Full text of DOI:10.1055/s-0032-1323760

Original Article 537
Synthesis and Biological Evaluation of a
6-Aminofuro[3,2–c]pyridin-3(2H)-one Series of GPR
119 Agonists
Authors
M. Sakairi, M. Kogami, M. Torii, Y. Kuno, Y. Ohsawa, M. Makino, D. Kataoka, R. Okamoto, T. Miyazawa,
M. Inoue, N. Takahashi, S. Harada, N. Watanabe
Affiliation
Drug Discovery Laboratories, Sanwa Kagaku Kenkyusho Co., Ltd.; Hokusei-cho, Inabe, Mie, Japan
Key words
Abstract
played strong to moderate inhibition of human
▶
●
human ether-à-go-go
ether-à-go-go related gene channel. Attenuation
of the basicity of the amino group by replacing
the adjacent benzene ring with electron-defi-
cient heteroaromatic rings provided several het-
erocyclic cores among which 6-aminofuro[3,2–c]
pyridin-3(2H)-one was selected as a promising
scaffold. Further optimization around the side
chain moiety led to the discovery of 17i, which
showed not only strong human GPR119 agonistic
activity (EC50 =14nM), but also beneficial effects
on gastric emptying and plasma total glucagon-
like peptide-1 levels in mice.
▼
related gene channel inhibi-
tion
G
protein-coupled receptor 119 (GPCR 119
(GPR119)) agonists have received considerable
attention as a promising therapeutic option for
treatment of type 2 diabetes mellitus. GPR119
is one of the GPCRs expressed in pancreatic islet
β-cells and its activation enhances stimula-
tion of insulin secretion in a glucose-dependent
manner. We have recently described a series of
6-amino-1H-indan-1-ones as potent, selective,
and orally bioavailable GPR119 agonists with an
amino group that plays important roles not only
in their drug-like properties, such as high aque-
ous solubility, but also in their potent agonistic
activity. However, many of these compounds dis-
▶
●
6-aminofuro[3,2-c]pyridin-
3(2H)-one
▶
gastric emptying
glucagon-like peptide-1
●
▶
●
Supporting information available online at http://
www.thieme-connect.de/ejournals/toc/amf
Introduction
dependent manner. In mice, expression of GPR119
has been detected in intestinal L- and K-cell lines,
and a GPR119 agonist, AR231453, has been shown
to enhance secretion of GLP-1 and glucose-depend-
ent insulinotropic polypeptide in glucose-chal-
lenged mice [6]. Therefore, several agonists such as
received 11.07.2012
accepted 13.08.2012
▼
Obesity is strongly associated with insulin resist-
ance and can therefore be problematic for man-
Bibliography
DOI http://dx.doi.org/
10.1055/s-0032-1323760
Published online:
September 12, 2012
Arzneimittelforschung 2012;
62: 537–544
© Georg Thieme Verlag KG
Stuttgart · New York
ISSN 0004-4172
agement of type
2 diabetes mellitus [1,2].
However, oral medications such as sulfonylureas
and thiazolidinediones are known to be difficult
to achieve weight loss. Glucose-dependent insu-
lin secretagogues, such as glucagon-like pep-
tide-1 (GLP-1) analogs and dipeptidyl peptidase
IV (DPP-4) inhibitors, have recently emerged as
new agents for the treatment of type 2 diabetes
mellitus [3]. In addition to improving glycemic
control and minimizing hypoglycemia, GLP-1
analogs have been demonstrated to produce
weight loss, while DPP-4 inhibitors have been
shown to induce no body weight gain.
In line with GLP-1 related drugs, G protein-coupled
receptor 119 (GPCR 119 (GPR119)) agonists have
received considerable attention as a promising
therapeutic option for the treatment of type 2 dia-
betes mellitus [4,5]. GPR119 is expressed in pan-
creatic islet β-cells, and its activation enhances
stimulation of insulin secretion in a glucose-
APD668 [7], MBX-2982 and GSK-1292263A have
▶
been under development ( Fig. 1) [ 5 – 9 ] .
●
In previous communications [10,11], we reported
a series of 6-amino-1H-indan-1-ones (1a-c) as
potent, selective, orally bioavailable GPR119 ago-
nists with an amino group that plays important
roles not only in their drug-like properties, such as
high aqueous solubility, but also in their potent
agonistic activity. However, many of these com-
pounds displayed strong to moderate inhibition of
human ether-à-go-go related gene (hERG) chan-
nel. Further optimization efforts have been made
to overcome this problem. Herein, we report a
6-aminofuro[3,2-c]pyridine series of GPR119 ago-
nists with enhanced activity and reduced hERG
channel inhibition.
Correspondence
N. Watanabe
Drug Discovery Laboratories
Sanwa Kagaku Kenkyusho Co.,
Ltd.
363 Shiosaki
Hokusei-cho
Inabe
Mie 511-0406
Japan
Tel.: +81/594/72 6221
Fax: +81/594/82 0072
no_watanabe@skk-net.com
Sakairi M et al. Synthesis and Biological Evaluation… Arzneimittelforschung 2012; 62: 537–544

538 Original Article
Fig. 1 GPR119 agonists.
Materials and methods
6-Amino-3-methoxycarbonylmethoxy-pyridine-2-
carboxylic acid methyl ester (3b)
▼
Chemistry
Method B: A suspension of 2b (1.81g, 10.8mmol), methyl bromoac-
etate (1.04mL, 11.3mmol) and cesium carbonate (7.57g, 23.2mmol)
in acetonitrile (75mL) was stirred at room temperature for 15h.
Methyl bromoacetate (500μL, 5.43mmol) was further added, and
the mixture was stirred at room temperature for an additional 7h.
The mixture was then diluted with water and extracted with EtOAc.
The organic layer was dried over anhydrous Na2SO4 and evaporated,
and the residue was purified by silica gel column chromatography
(MeOH: CHCl3=1: 10) to give 3b (2.12g, yield 82%).
All commercially available reagents and solvents were used
without further purification. Reactions were carried out using
oven-dried flasks or glassware, mixtures were stirred with mag-
netic stirring bars and concentrated using a standard rotary
evaporator, unless otherwise noted. Procedures for preparation
▶
of intermediates 2b, d and corresponding alcohols in Fig. 5
●
were carried out as described previously. 1H NMR spectra were
recorded by a JEOL JNM-ECP400 spectrometer operating at 400MHz
at 25°C with tetramethylsilane as internal standard. Data are
reported as follows: chemical shift in ppm (δ), integration, multi-
plicity (s=singlet, d=doublet, t=triplet, q=quartet, br=broad,
m=multiplet), and coupling constant (Hz). LC/MS spectra were
determined on a Waters ZMD2000 equipped with a Waters 2690
injector and a PDA detector operating at 210–400nm and inter-
faced with a Micromass ZMD mass spectrometer. High-resolution
mass spectra (HRMS) were recorded on a Thermo. LTQ Orbitrap.
1H NMR (CDCl3) δ: 7.35–7.30 (m, 1H), 6.66–6.61 (m, 1H), 4.63 (s,
2H), 4.50 (s, 2H), 3.95 (s, 3H), 3.79 (s, 3H). ESI-MS (m/e): 241
[M+H]+.
Methyl 2-amino-5-(2-methoxy-2-oxoethoxy)
isonicotinate (3d)
1H NMR (CDCl3) δ: 8.14 (d, J=0.8Hz, 1H), 6.69 (d, J=0.8Hz, 1H),
4.62 (s, 2H), 4.35 (brs, 2H), 3.92 (s, 3H), 3.83 (s, 3H). ESI-MS
(m/e): 241 [M+H]+.
Representative procedure for compound 4
Methyl 6-amino-3-(3-methoxy-3-oxopropyl)picolinate
(3a)
2-Amino-5H-cyclopenta-[b]pyridin-7(6H)-one (4a)
To a solution of 3a (2.0g, 8.39mmol) in dry DMF (40mL) under
argon was stirred potassium tert-butoxide (2.22g, 16.8mmol) at
0°C. The mixture was warmed to room temperature and stirred
at the same temperature for 1.5h. Next, the mixture was cooled
to 0°C and neutralized with 2N HCl (10mL). Sodium chloride
(984mg, 16.8mmol) was then added to the mixture, and the
resulting suspension was stirred at 140°C for 30min. The reac-
tion mixture was evaporated, and the residue was diluted with
90% methanolic CHCl3. Insoluble materials were filtered off, and
the filtrate was concentrated. The residue was purified by silica
gel column chromatography (MeOH: CHCl3 =1: 50) to give 4a as
a brown solid (0.697g, yield 56%).
Method A: To a degassed solution of 2a (5.57g, 24.1mmol), methyl
acrylate (6.5mL, 72.3mmol), triethylamine (10.1mL, 72.3mmol) in
DMF (30mL) was added dichlorobis(tri-o-tolyl-phosphine) palla-
dium (II) (0.95g, 1.2mmol). The resulting solution was stirred with
heating at 80°C for 17h under argon atmosphere. The reaction mix-
ture was then evaporated, and the residue was diluted with Et2O/
hexane=1/1. The resultant precipitate was filtered and washed with
1
hexane to give an unsaturated ester as a yellow solid (4.42g): H
NMR (CDCl3) δ: 8.20 (d, 1H), 7.76 (d, 1H), 6.66 (d, 1H), 6.23 (d, 1H),
4.87 (br s, 2H), 3.99 (s, 3H), 3.80 (s, 3H): ESI-MS (m/e): 236 [M+H]+,
which was used in the next reaction without further purification.
To a solution of the unsaturated ester obtained above (4.42g,
18.7mmol) in EtOH (40mL) was added 10% Pd/C (0.44g). The
mixture was stirred under hydrogen atmosphere at 50°C for 8h.
The catalyst was filtered off, and the filtrate was concentrated
under reduced pressure to give the title compound as a yellow
solid (4.16g, yield 72%, 2 steps).
1H NMR (CDCl3) δ: 7.60 (d, J=8.4Hz, 1H), 6.71 (d, J=8.4Hz, 1H),
6.44 (d, J=5.3Hz, 1H), 4.75 (br s, 2H), 3.03–2.94 (m, 2H), 2.75–
2.65 (m, 2H). ESI-MS (m/e): 149 [M+H]+.
5-Amino-furo[3,2–b]pyridin-3-one (4b)
1H NMR (CDCl3) δ: 7.52–7.48 (m, 1H), 6.75 (d, J=9.1Hz, 1H), 6.19
(s, 2H). ESI-MS (m/e): 151 [M+H]+.
1H NMR (DMSO-d6) δ: 7.36 (d, J=8.5Hz, 1H), 6.54 (d, J=8.4Hz,
1H), 6.10 (br s, 1H), 3.78 (s, 3H), 3.57 (s, 3H), 2.69–2.65 (m, 2H),
2.35–2.30 (m, 2H). ESI-MS (m/e): 238 [M+H]+.
3-Amino-6,7-dihydro-5H-cyclopenta[c]pyridin-5-one
(4c)
Methyl 2-amino-5-(3-methoxy-3-oxopropyl)isonicotinate
(3c)
1H NMR (CDCl3) δ: 8.35 (s, 1H), 6.75 (s, 1H), 4.67 (brs, 2H), 3.12–
3.02 (m, 2H), 2.76–2.66 (m, 2H). ESI-MS (m/e): 149 [M+H]+.
1H NMR (CDCl3) δ: 8.04 (s, 1H), 6.95 (s, 1H), 4.49 (brs, 2H), 3.90
(s, 3H), 3.66 (s, 3H), 3.10 (t, J=7.6Hz, 2H), 2.60 (t, J=7.6Hz, 2H).
ESI-MS (m/e): 239 [M+H]+.
5-Aminofuro[2,3-c]pyridin-3(2H)-one (4d)
1H NMR (CDCl3) δ: 8.24 (d, J=1.1Hz, 1H), 6.68 (d, J=1.1Hz, 1H),
4.63 (s, 2H), 4.39 (brs, 2H). ESI-MS (m/e): 151 [M+H]+.
Sakairi M et al. Synthesis and Biological Evaluation… Arzneimittelforschung 2012; 62: 537–544

Original Article 539
Ethyl 4-(2-ethoxy-2-oxoethoxy)-2-((4-methoxybenzyl)
amino)pyrimidine-5-carboxylate (6)
2-Aminofuro[2,3-d]pyrimidin-5(6H)-one (8)
To a suspension of 7 (61mg, 0.27mmol) in MeOH (2mL) was
added conc. HCl (455μL, 5.4mmol), and the mixture was
refluxed for 1h. The mixture was then cooled to 0°C and neu-
tralized with satd. NaHCO3. The precipitate was filtrated and
washed with H2O, and the filtrate was extracted with CHCl3. The
organic layer was dried over anhydrous Na2SO4 and concen-
trated. The residue was purified by PLC (MeOH: CHCl3 =1: 9) to
give 8 (20mg, yield 49%) as a white solid.
Sodium hydride (40% in oil, 1.76g, 44mmol) was added to a
solution of ethyl glycolate (2.1mL, 22mmol) in THF (50mL) at
0°C, and the mixture was stirred for 30min. Next, 5 (4.6g,
20mmol) was added, and the mixture was stirred at room tem-
perature and quenched with crashed ice. The resulting mixture
was extracted with EtOAc, and the organic layer was washed
with brine, dried over anhydrous Na2SO4 and concentrated. The
residue was purified by silica gel column chromatography
(EtOAc: hexane=1: 3) to give an ester as a white solid (2.4g,
yield 40%): 1H NMR (CDCl3) δ: 8.86 (s, 1H), 4.99 (s, 2H), 4.37 (q,
J=7.1Hz, 2H), 4.24 (q, J=7.1Hz, 2H), 2.51 (s, 3H), 1.38 (t, J=7.1Hz,
3H), 1.27 (t, J=7.1Hz, 3H): ESI-MS (m/e): 301 [M+H]+, which
was used in the next step without further purification.
To a solution of the ester prepared above (4.1g, 13.7mmol) in
CH2Cl2 (110mL) was added m-chloroperoxybenzoic acid (6.82g,
27.3mmol) at 0°C. The mixture was allowed to warm to room
temperature and stirred for 2h. Water (100mL) and 5 N NaOH
solution (8mL, 40mmol) were then added, and the layers were
separated. The aqueous layer was extracted with CH2Cl2, and the
combined organic layers were washed with brine, dried over
anhydrous Na2SO4 and concentrated. The residue was dissolved
in N-methylpyrrolidone (45mL), and p-methoxybenzylamine
(2.14mL, 16.4mmol) and triethylamine (4.57mL, 32.8mmol)
were added to the solution. The resulting mixture was stirred
overnight, poured into H2O and extracted with EtOAc. The
organic layer was washed with brine, dried over anhydrous
Na2SO4 and concentrated. The residue was purified by silica gel
column chromatography (EtOAc: hexane=1: 3) to give 6 (3.35g,
yield 63%) as a white solid.
1H NMR (DMSO-d6) δ: 8.58 (s, 1H), 8.04 (brs, 1H), 7.96 (brs, 1H),
4.72 (s, 2H). ESI-MS (m/e): 152 [M+H]+.
Methyl 4-(benzyloxy)-6-chloronicotinate (10)
To a solution of benzyl alcohol (269mL, 2.6mol) in THF (2L) was
added NaH (104g in oil, 2.6mol) at 0°C. After stirring at room tem-
perature for 30min, a solution of 9 (192g, 1mol) in THF (100mL)
was added dropwise to the mixture at 0°C. The resulting mixture
was stirred at room temperature overnight and then diluted with
water (1L). The solvent was evaporated in vacuum, and the residue
was washed with Et2O. The aqueous layer was acidified with 6 N
HCl to pH 1 and extracted with EtOAc. The organic layer was
washed with brine, dried over anhydrous Na2SO4 and concen-
trated. The residue was dissolved in DMF (1L), and K2CO3 (138g,
1mol) was added portionwise to the solution. After stirring at
room temperature for 30min, iodomethane (258g, 1.82mol) was
added dropwise to the mixture, and the resulting mixture was
stirred at room temperature for an additional 2h, and then parti-
tioned between H2O (1L) and EtOAc (1L). The organic layer was
washed with brine, dried over anhydrous Na2SO4 and concen-
trated in vacuum to give 10 (230g, 90%) as a white solid.
1H NMR (CDCl3) δ: 8.74 (s, 1H), 7.33–7.49 (m, 5H), 5.24 (s, 2H),
3.92 (s, 3H). ESI-MS (m/e): 278 [M+H]+.
1H NMR (CDCl3) δ: 8.82 (brs, 0.75H), 8.70 (brs, 0.75H), 7.21 (d,
J=7.7Hz, 2H), 6.87 (d, J=7.7Hz, 2H), 5.88 (brs, 0.75H), 5.45 (brs,
0.25H), 4.89 (s, 2H), 4.61 (brs, 0.5H), 4.49 (brs, 1.5H), 4.32 (q,
J=7.1Hz, 2H), 4.15 (brs, 2H), 3.80 (s, 3H), 1.35 (t, J=7.1Hz, 3H),
1.21 (brs, 3H). ESI-MS (m/e): 390 [M+H]+.
Methyl 4-hydroxy-6-((4-methoxybenzyl)amino)
nicotinate (11)
To a solution of 10 (52g, 187mmol) in N-methylpyrrolidone
(500mL) were added p-methoxybenzyl amine (51g, 374mmol)
and triethylamine (75g, 748mmol), and the mixture was stirred at
80°C overnight. The reaction mixture was then diluted with H2O
(300mL) and extracted with EtOAc (300mL). The organic layer was
washed with brine, dried over anhydrous Na2SO4 and concen-
trated. The residue was purified by silica gel column chromatogra-
phy (EtOAc: hexane=1:1) to give an ester as a white solid (28g,
yield 40%): 1H NMR (CDCl3) δ: 8.63 (s, 1H), 7.43 (d, J=7.2Hz, 2H),
7.37 (t, J=7.2Hz, 2H), 7.30 (t, J=7.2Hz, 1H), 7.23 (d, J=8.7Hz, 2H),
6.87 (d, J=8.7Hz, 2H), 5.81 (s, 1H), 5.19 (s, 2H), 5.11 (s, 2H), 4.41 (d,
J=5.6Hz, 2H), 3.85 (s, 3H), 3.81 (s, 3H): ESI-MS (m/e): 379 [M+H]+,
which was used in the next step without further purification.
A mixture of the ester obtained above (28g, 75mmol) and 10%
Pd/C (2.8g) in MeOH (1 L) was stirred under hydrogen atmos-
phere for 2h at room temperature, and CHCl3 (2.0L) was added.
The catalyst was filtered off and rinsed with 90% methanolic
CHCl3, and the filtrate was concentrated to give 11 (20g, yield
92%), which was pure enough for the next reaction.
Ethyl 2-amino-5-oxo-5,6-dihydrofuro[2,3-d]pyrimidine-
6-carboxylate (7)
A solution of 6 (2.73g, 7mmol) in trifluoroacetic acid (40mL)
was refluxed for 2 days, evaporated, and then azeotroped with
toluene. Chloroform and satd. NaHCO3 were added to the resi-
due and the phases were separated. The aqueous layer was
extracted with CHCl3, and the combined organic layers were
washed with brine, dried over anhydrous Na2SO4 and concen-
trated. The residue was triturated in Et2O, filtered, rinsed with
cold Et2O and dried under reduced pressure to give an ester
1
(1.72g, yield 91%) as a yellow powder: H NMR (CDCl3) δ: 1.26
(t, J=7.0Hz, 3H), 1.36 (t, J=7.0Hz, 3H), 4.23 (q, J=7.0Hz, 2H),
4.34 (q, J=7.0Hz, 2H), 4.93 (s, 2H), 5.23 (brs, 2H), 8.75 (s, 1H):
ESI-MS (m/e): 270 [M+H]+, which was used in the next step
without further purification.
To a solution of the ester obtained above (470mg, 1.74mmol) in
DMF (15mL) was added potassium tert-butoxide (490mg,
4.4mmol) at −15°C, and the mixture was allowed to warm to
room temperature. After stirring for 30min, the solution was
cooled to 0°C, neutralized with 6 N HCl and evaporated. The resi-
due was purified by silica gel column chromatography (MeOH:
CHCl3 =1: 50) to give 7 (80mg, yield 21%) as a brown solid.
1H NMR (DMSO-d6) δ: 8.65 (1H, s), 8.32 (1H, brs), 8.23 (1H, brs),
5.57 (1H, s), 4.21 (q, J=7.1Hz, 2H), 1.22 (t, J=7.1Hz, 3H). ESI-MS
(m/e): 224 [M+H]+.
1H NMR (DMSO-d6) δ: 8.40 (s, 1H), 8.10 (brs, 1H), 7.26 (d,
J=8.7Hz, 2H), 6.91 (d, J=8.7Hz, 2H), 6.04 (s, 1H), 4.43 (d, J=4.8Hz,
2H), 3.81 (s, 3H), 3.73 (s, 3H). ESI-MS (m/e): 289 [M+H]+.
Methyl 4-(2-methoxy-2-oxoethoxy)-6-((4-
methoxybenzyl)amino)nicotinate (12)
A suspension of 11 (22g, 75mmol) and K2CO3 (16g, 113mmol)
in DMF (50mL) was stirred at 30°C for 30min, and methyl bro-
Sakairi M et al. Synthesis and Biological Evaluation… Arzneimittelforschung 2012; 62: 537–544

540 Original Article
moacetate (17.17g, 113mmol) was added. The resulting mix-
Method B: General procedure with reductive amination T o a
solution of amine (0.1mmol) and aldehyde (0.1mmol) in AcOH
(500μL) was added NaBH(OAc)3 (0.2mmol), and the reaction
mixture was stirred for 1h at room temperature. The mixture
was then neutralized with satd. NaHCO3 and extracted with
CHCl3. The organic layer was washed with brine, dried over
anhydrous Na2SO4, and concentrated. The residue was purified
by PLC.
ture was stirred at 30°C overnight, diluted with water (100mL),
and then extracted with EtOAc (150mL×3). The combined
organic layers were washed with brine, dried over Na2SO4, fil-
tered, evaporated, and the residue was washed with MeOH
(100mL) to give 12 as a white solid (15g, yield 56%).
1H NMR (CDCl3) δ: 8.65 (s, 1H), 7.25 (d, J=8.7Hz, 2H), 6.88 (d,
J=8.7Hz, 2H), 5.60 (s, 1H), 5.23 (brs, 1H), 4.65 (s, 2H), 4.43 (d,
J=5.6Hz, 2H), 3.85 (s, 3H), 3.80 (s, 3H), 3.75 (s, 3H). ESI-MS
(m/e): 361 [M+H]+.
2-((3-(1-(5-Ethylpyrimidin-2-yl)piperidin-4-yl)propyl)
amino)-5H-cyclopenta[b]pyridin-7(6H)-one (15a)
1H NMR (CDCl3) δ: 8.15 (s, 2H), 7.56 (d, J=8.6Hz, 1H), 6.61 (d,
J=8.6Hz, 1H), 4.83 (s, 1H), 4.72–4.63 (m, 2H), 3.38–3.32 (m, 2H),
3.08–2.90 (m, 2H), 2.86–2.76 (m, 2H), 2.73–2.55 (m, 2H), 2.50–
2.45 (m, 2H), 1.78–1.71 (m, 2H), 1.68–1.62 (m, 2H), 1.61–1.45
(m, 1H), 1.40–1.30 (m, 2H), 1.24–1.10 (m, 4H). HRMS ESI calcd
for C22H29N5O 380.2445, found 380.2448.
6-Aminofuro[3,2-c]pyridin-3(2H)-one (13)
To a solution of 12 (18g, 50mmol) in THF (150mL) was added
LDA (2M, 50ml, 200mmol) at −40°C, and the mixture was
stirred at the same temperature for 2h. The mixture was then
quenched with satd. NH4Cl (100mL) and extracted with EtOAc.
The organic layer was concentrated and the residue was recrys-
tallized from MeOH to give the β-keto ester as a white solid
(11.5g, yield 70%): 1H NMR (CDCl3) δ: 8.49 (s, 1H), 7.26 (d,
J=8.7Hz, 8H), 6.90 (d, J=8.7Hz, 2H), 6.01 (d, J=0.5Hz, 1H), 5.75
(brs, 1H), 5.14 (s, 1H), 4.47 (brs, 2H), 3.86 (s, 3H), 3.81 (s, 3H).
ESI-MS (m/e): 329 [M+H]+, which was used in the next reaction
without further purification.
5-((3-(1-(5-Ethylpyrimidin-2-yl)piperidin-4-yl)propyl)
amino)furo[3,2-b]pyridin-3(2H)-one (15b)
1H NMR (CDCl3) δ: 8.16 (s, 2H), 7.33 (d, J=9.2Hz, 1H), 6.69 (d,
J=9.2Hz, 1H), 4.70 (s, 1H), 4.67–4.65 (m, 3H), 4.58 (s, 1H), 3.37
(dd, J=12.5, 7.0Hz, 2H), 2.83 (td, J=13.1, 2.6Hz, 2H), 2.45 (q,
J=7.6Hz, 2H), 1.79–1.73 (m, 2H), 1.68–1.64 (m, 2H), 1.59–1.51
(m, 1H), 1.40–1.24 (m, 4H), 1.18 (t, J=7.6Hz, 3H). HRMS ESI
calcd for C21H27N5O2 382.2237, found 382.2239.
To a solution of the β-keto ester obtained above (11.5g, 35mmol)
in MeOH (100mL) was added conc. HCl (100mL), and the reac-
tion mixture was refluxed for 2h. The resulting mixture was
concentrated to give the corresponding decarboxylated product
1
as a yellow solid (9.5g, yield 99%): H NMR (CDCl3) δ: 8.46 (s,
5-((3-(1-(5-Ethylpyrimidin-2-yl)piperidin-4-yl)propyl)
amino)furo[2,3-c]pyridin-3(2H)-one (15c)
1H), 7.26 (d, J=8.7Hz, 7H), 6.90 (d, J=8.7Hz, 2H), 5.93 (s, 1H),
4.62 (s, 2H), 4.45 (d, J=5.6Hz, 2H), 3.81 (s, 3H): ESI-MS (m/e):
271 [M+H]+.
1H NMR (CDCl3) δ: 8.35 (s, 1H), 8.16 (s, 1H), 6.60 (s, 1H), 4.70–
4.48 (m, 3H), 3.30–3.20 (m, 2H), 3.09–3.02 (m, 2H), 2.95–2.80
(m, 2H), 2.73–2.67 (m, 2H), 2.45 (q, J=7.6Hz, 2H), 1.80–1.60 (m,
4H), 1.61–1.47 (m, 2H), 1.42–1.32 (m, 2H), 1.23–1.13 (m, 5H).
HRMS ESI calcd for C22H29N5O 380.2444, found 380.2448.
A solution of the decarboxylated product prepared above (28.5g,
105mmol) in TFA (15mL) was heated at 60°C for 4h. The mix-
ture was evaporated, and the residue was partitioned between
EtOAc (500mL) and 6 N HCl. The pH of the aqueous layer was
adjusted to pH 9 with NaHCO3 in an ice-bath, and the precipi-
tates were collected to give 4.6g of 13 as a yellow solid. The fil-
trate was extracted with EtOAc, and the organic layer was
washed with brine, dried over Na2SO4, and concentrated to give
an additional 8.2g of 13 (combined yield 80%).
2-((3-(1-(5-Ethylpyrimidin-2-yl)piperidin-4-yl)propyl)
amino)furo[2,3-d]pyrimidin-5(6H)-one (16a)
1H NMR (CDCl3) δ: 8.67 (s, 0.4H), 8.56 (s, 0.6H), 8.16 (s, 2H), 6.05
(brs, 0.6H), 5.83 (brs, 0.4H), 4.67–4.71 (m, 2H), 4.66 (s, 1.3H),
4.63 (s, 0.7H), 3.49–3.58 (m, 2H), 2.80–2.86 (m, 2H), 2.45 (q,
J=7.6Hz, 2H), 1.66–1.78 (m, 4H), 1.54–1.56 (m, 1H), 1.32–1.38
(m, 2H), 1.18 (t, J=7.6Hz, 3H), 1.12–1.23 (m, 2H). HRMS ESI
calcd for C20H26N6O2 383.2189, found 383.2197.
1H NMR (DMSO-d6) δ: 8.31 (s, 1H), 7.13 (br, 2H), 5.98 (s, 1H),
4.69 (s, 2H). ESI-MS (m/e): 151 [M+H]+.
Preparation of compounds 15a–c, 16a–b and 17a–j
General procedure for preparation of aldehydes
To a solution of the corresponding alcohol (1mmol) in CH2Cl2
(10mL) was added Dess-Martin periodinane (1.1mmol) at 0°C,
and the mixture was stirred for 3h at room temperature. To the
mixture was the added H2O and 5 N NaOH solution (6mmol),
and the whole was extracted with CH2Cl2. The organic layer was
washed with brine, dried over anhydrous Na2SO4, concentrated
and the crude product was subjected to the next reaction with-
out further purification.
Tert-butyl
4-(3-((5-oxo-5,6-dihydrofuro[2,3-d]pyrimidin-2-yl)
amino)propyl)piperidine-1-carboxylate (16b)
1H NMR (CDCl3) δ: 8.67 (s, 0.4H), 8.56 (s, 0.6H), 6.21 (brs, 0.6H),
5.94 (brs, 0.4H), 4.66 (s, 1.3H), 4.63 (s, 0.7H), 4.10 (brs, 2H), 3.48–
3.57 (m, 2H), 2.67 (t, J=11.7Hz, 2H), 1.63–1.71 (m, 5H), 1.45 (s,
9H), 1.33–1.39 (m, 2H), 1.12–1.23 (m, 2H). HRMS ESI calcd for
C19H28N4O4 377.2183, found 377.2193.
6-((3-(1-(5-Ethylpyrimidin-2-yl)piperidin-4-yl)propyl)
amino)furo[3,2-c]pyridin-3(2H)-one (17a)
Method A: General procedure with reductive amination T o a
solution of amine (0.1mmol) and aldehyde (0.1mmol) in CH2Cl2
(2mL) was added NaBH(OAc)3 (0.2mmol), and the reaction mix-
ture was stirred overnight at room temperature. The mixture
was poured into satd. NaHCO3 and extracted with CH2Cl2. The
organic layer was washed with brine, dried over anhydrous
Na2SO4, and concentrated. The residue was purified by PLC.
1H NMR (CDCl3) δ: 8.46 (s, 1H), 8.16 (s, 2H), 5.88 (s, 1H), 5.32
(brs, 1H), 4.70 (d, J=12.5Hz, 2H), 4.61 (s, 2H), 3.28 (dd, J=12.5,
6.3, 2H), 2.84 (td, J=13.1, 2.6Hz, 2H), 2.45 (q, J=7.6Hz, 2H),
1.83–1.63 (m, 5H), 1.43–1.32 (m, 2H), 1.26–1.11 (m, 5H). HRMS
ESI calcd for C21H27N5O2 382.2237, found 382.2244.
Sakairi M et al. Synthesis and Biological Evaluation… Arzneimittelforschung 2012; 62: 537–544

Original Article 541
Tert-butyl
6-((3-(1-(5-Ethylpyrimidin-2-yl)piperidin-4-yl)butyl)
4-(3-((3-oxo-2,3-dihydrofuro[3,2-c]pyridin-6-yl)amino)
propyl)piperidine-1-carboxylate (17b)
amino)furo[3,2–c]pyridin-3(2H)-one (17i)
1H NMR (CDCl3) δ: 8.46 (s, 1H), 8.16 (s, 2H), 5.88 (s, 1H), 5.35
(brs, 1H), 4.75–4.79 (m, 2H), 4.61 (s, 2H), 3.20–3.41 (m, 2H),
2.75–2.83 (m, 2H), 2.45 (q, J=8.0Hz, 2H), 1.74–1.81 (m, 1H),
1.66–1.70 (m, 2H), 1.45–1.52 (m, 3H), 1.23–1.36 (m, 2H), 1.18 (t,
J=8.0Hz, 3H), 0.94 (d, J=8.0Hz, 3H). HRMS ESI calcd for
C22H29N5O2 396.2393, found 396.2387.
1H NMR (CDCl3) δ: 8.46 (s, 1H), 5.87 (s, 1H), 5.34 (brs, 1H), 4.61
(s, 2H), 4.09 (brs, 2H), 3.27 (d, J=6.6, 2H), 2.67 (t, J=12.6Hz, 2H),
1.71–1.64 (m, 5H), 1.45 (s, 9H), 1.38–1.32 (m, 2H), 1.25–1.10 (m,
2H). HRMS ESI calcd for C20H29N3O4 376.2230, found 376.2240.
6-((3-(1-(5-Methoxypyrimidin-2-yl)piperidin-4-yl)propyl)
amino)furo[3,2-c]pyridin-3(2H)-one (17c)
6-((3-(1-(3-Isopropyl-1,2,4-oxadiazol-5-yl)piperidin-4-yl)
butyl)amino)furo[3,2-c]pyridin-3(2H)-one (17j)
1H NMR (CDCl3) δ: 8.46 (s, 1H), 8.08 (s, 2H), 5.88 (s, 1H), 5.45
(brs, 1H), 4.67–4.54 (m, 4H), 3.79 (s, 3H), 3.28 (d, J=6.2, 2H), 2.82
(td, J=13.1, 2.6Hz, 2H), 1.86–1.61 (m, 4H), 1.59–1.53 (m, 1H),
1.44–1.32 (m, 2H), 1.27–1.12 (m, 2H). HRMS ESI calcd for
C20H25N5O3 384.2029, found 384.2041.
1H NMR (CDCl3) δ: 8.46 (s, 1H), 5.88 (s, 1H), 5.29 (brs, 1H), 4.62
(s, 2H), 4.15–4.23 (m, 2H), 3.21–3.43 (m, 2H), 2.96–3.03 (m, 2H),
2.83–2.93 (m, 1H), 1.68–1.80 (m, 3H), 1.32–1.58 (m, 5H), 1.28 (d,
J=8.0Hz, 6H), 0.95 (d, J=8.0Hz, 3H). HRMS ESI calcd for
C21H29N5O3 400.2342, found 400.2339.
6-((3-(1-(5-Fluoropyrimidin-2-yl)piperidin-4-yl)propyl)
amino)furo[3,2–c]pyridin-3(2H)-one (17d)
1H NMR (CDCl3) δ: 8.46 (s, 1H), 8.17 (s, 2H), 5.88 (s, 1H), 5.31
(brs, 1H), 4.59–4.69 (m, 4H), 3.22–3.34 (m, 2H), 2.79–2.90 (m,
2H), 1.11–1.82 (m, 9H). HRMS ESI calcd for C19H22FN5O2
372.1830, found 372.1835.
Biology
▼
In vitro assays
hERG binding assay
hERG channel inhibition was assessed using PredictorTM hERG
Fluorescence Polarization Assay Kit (Invitrogen, Carlsbad, CA).
The positive control, E-4031, and test compounds were dis-
solved in DMSO. The assay was performed according to the
manufacture’s protocol.
6-((3-(1-(5-(Trifluoromethyl)pyrimidin-2-yl)piperidin-4-
yl)propyl)amino)furo[3,2–c]pyridin-3(2H)-one (17e)
1H NMR (CDCl3) δ: 8.50–8.41 (m, 3H), 5.88 (d, J=0.5Hz, 1H), 5.46
(brs, 1H), 4.87–4.78 (m, 2H), 4.61 (s, 2H), 3.29 (dd, J=12.5, 6.4Hz,
2H), 2.91 (td, J=13.1, 2.6Hz, 2H), 1.85–1.76 (m, 2H), 1.75–1.67
(m, 2H), 1.65–1.57 (m, 1H), 1.43–1.33 (m, 2H), 1.23–1.11 (m,
2H). HRMS ESI calcd for C20H22F3N5O2 422.1798, found 422.1803.
Cell-based cAMP functional assay
Cellular cAMP was measured using HTRF cAMP HiRange reagent
(CISBIO, Cedex, France). CHO-K1 cells expressing human GPR119
receptors were obtained from Applied Cell Sciences and were
grown in flasks containing F-12 medium supplemented with
10% FBS, 1% non essential amino acids, 20mM HEPES, 50units/
ml penicillin, 50μL/mL streptomycin, and 400μg/mL geneticin.
CHO-K1 cells expressing mouse GPR119 receptors were pre-
pared in house and were grown in flasks containing F-12
medium supplemented with 10% FBS, 1% non essential amino
acids, 20mM HEPES, 50units/mL penicillin, 50μL/mL strepto-
mycin, and 400μg/ml geneticin. For the hGPR119 or mGPR119
functional assay, cells expressing hGPR119 or mGPR119 were
harvested, re-suspended in incubation buffer (F-12 medium,
20mM HEPES, 1 mM IBMX), and dispensed into 384-well plates
at a density of 1.5×104 cells/well in the presence or absence of
test compounds. The cells were then incubated at 37°C for
30min, after which cAMP-d2–conjugated antibody and anti-
cAMP-cryptase–conjugated antibody were added to the plate.
After incubation for 60min at room temperature, cellular cAMP
was measured using a HTRF® (TR-FRET) Microplate Reader
ARTEMIS (Furuno Electric Co., Ltd., Tokyo, Japan). Data were
analyzed based on the ratio of fluorescence intensity of each
well at 620 and 665nm. Sigmoidal dose-response equation was
used to determine EC50 and Emax values, which represent rela-
tive efficacy defined as the ratio of test compound response to
AR231453 maximum response.
6-((3-((1R,3S,5S)-8-(5-Ethylpyrimidin-2-yl)-8-
azabicyclo[3.2.1]octan-3-yl)propyl)amino)furo[3,2-c]
pyridin-3(2H)-one (17f)
1H NMR (CDCl3) δ: 8.45 (s, 1H), 8.16 (s, 2H), 5.85 (s, 1H), 5.41 (s,
1H), 4.68–4.63 (m, 2H), 4.62–4.59 (m, 2H), 3.25–3.19 (m, 2H),
2.49–2.42 (m, 2H), 2.32–2.29 (m, 2H), 2.08–2.04 (m, 2H), 1.78–
1.75 (m, 2H), 1.68–1.64 (m, 2H), 1.64–1.60 (m, 2H), 1.58–1.55
(m, 1H), 1.32–1.28 (m, 2H), 1.31–1.19 (m, 3H). HRMS ESI calcd
for C23H29N5O2 408.2394, found 408.2393.
6-((3-(((1R,5S)-8-(5-Ethylpyrimidin-2-yl)-8-
azabicyclo[3.2.1]octan-3-yl)oxy)propyl)amino)furo[3,2-
c]pyridin-3(2H)-one (17g)
1H NMR (CDCl3) δ: 8.46 (s, 1H), 8.18 (s, 2H), 6.06 (s, 1H), 5.91 (s,
1H), 4.64–4.61 (m, 4H), 3.56–3.52 (m, 3H), 3.45–3.39 (m, 2H),
2.46 (q, J=7.6Hz, 2H), 2.24–2.13 (m, 2H), 2.12–1.98 (m, 4H),
1.98–1.84 (m, 4H), 1.19 (t, J=7.6Hz, 3H). HRMS ESI calcd for
C23H29N5O3 424.2343, found 424.2341.
6-((3-(1-(3-Isopropyl-1,2,4-oxadiazol-5-yl)piperidin-4-yl)
propyl)amino)furo[3,2-c]pyridin-3(2H)-one (17h)
1H NMR (CDCl3) δ: 8.47 (s, 1H), 5.88 (s, 1H), 5.31 (s, 1H), 4.62 (s,
2H), 4.13 (d, J=12.9Hz, 2H), 3.29 (dd, J=12.3, 6.2Hz, 2H), 3.02
(td, J=13.0, 2.8Hz, 2H), 2.88 (sep, J=7.0Hz, 1H), 1.78 (d,
J=11.9Hz, 2H), 1.74–1.64 (m, 2H), 1.55–1.44 (m, 1H), 1.43–1.34
(m, 2H), 1.34–1.19 (m, 8H).
In vivo assays
HRMS ESI calcd for C20H27N5O3 386.2186, found 386.2195.
All in vivo protocols were approved by Sanwa Kagaku Kenky-
usho Animal Care Committee.
Male C57BL/6J mice (Charles River Laboratories, Yokohama,
Japan) were housed under a 12-h light-dark cycle and allowed
free access to water and a standard laboratory diet.
Sakairi M et al. Synthesis and Biological Evaluation… Arzneimittelforschung 2012; 62: 537–544

542 Original Article
Gastric emptying
Liquid-phase gastric emptying was assessed using the acetami-
nophen absorption test according to a literature method [19].
Male C57BL/6J mice, 11 week of age, were fasted overnight, and
orally given 10mg/kg of 17i or vehicle (5% DMSO, 0.1% Tween 80
and 0.5% methylcellulose) 30min before oral administration of
an aqueous solution of 20% glucose and 1% acetaminophen
(Sigma-Aldrich, St. Louis, MO) at a dose of 2g/kg glucose–100mg/
kg acetaminophen. Blood samples (40μL) were collected 10 and
20min after acetaminophen administration and plasma aceta-
minophen levels were measured using an acetaminophen assay
kit (Cambridge Life Sciences, Cambridge, U.K.).
GLP-1 secretion
Male C57BL/6J mice, 10 week of age, were fasted 5 h, and orally
administered 30mg/kg of 17i or vehicle (5% DMSO, 0.1% Tween
80 and 0.5% methylcellulose). Plasma total GLP-1 (both intact
GLP-1 (7-36) amide and its primary metabolite) levels 30min
after administration were measured by ELISA using anti-GLP-1
monoclonal antibodies.
Fig. 2 Synthesis of compounds 4. Reagents and conditions: from 2a
and 2c to 4a and 4c respectively. a (i) Methyl acrylate, PdCl2(Po-Tol3)2,
Et3N, DMF (ii) H2, Pd/C, EtOH b (i) tert-BuOK, DMF (ii) NaCl. Reagents and
conditions: from 2b and 2d to 4b and 4d respectively. a BrCH2CO2Me,
Cs2CO3, DMF b (i) tert-BuOK, DMF (ii) NaOH.
Statistical significance
The data are expressed as the mean±SEM (standard error of
mean). Statistical significance was determined using one-way
ANOVA and Dunnett multiple comparison test.
Results and Discussion
▼
Chemistry
Following a known approach to hERG optimization [12], our
strategy was based on attenuating the basicity of the amino
group by replacing the adjacent benzene ring with electron-
deficient heteroaromatic rings. From a literature precedent [13],
the bicyclic core systems containing these heteroaromatic rings
could be constructed by intramolecular Dieckmann condensa-
tion. Synthesis of the target compounds 15–17 could be accom-
plished by decarboxylation followed by hydrophobic chain
elongation achieved by reductive amination. This synthetic
route allowed for 2-round optimization with an array of hetero-
cyclic cores and side chains.
Fig. 3 Synthesis of compound 8. Reagents and conditions: a (i) HOCH-
2CO2Et, NaH, THF (ii) m-CPBA, DCM (iii) p-MPMNH2, Et3N, NMP b (i)
TFA(ii) tert-BuOK, DMF c conc. HCl, MeOH.
Thus, Heck reaction of 2a and 2c with methyl acrylate proceeded
smoothly without protecting the 2-amino group. After hydro-
genation, Dieckmann condensation of 3a and 3c followed by
decarboxylation gave the desired compounds 4a and 4c in good
yields. Synthesis of the oxa-analogues 4b and 4d followed the
same reaction sequence, except that selective O-aklylation of 2b
and 2d with α-haloacetate esters was carried out at the first step
▶
of introduction of the requisite acetate function ( Fig. 2). By
●
analogy, the 2-aminofuro[2,3-d]pyrimidin-5(6H)-one 8 and its
pyridine analogue 13 were prepared from the commercially
▶
available pyrimidine 5 and pyridine 9, respectively ( Fig. 3, 4).
●
An attempt to replace the chlorine atom of 14 with a p-methoxy-
benzyl amine was not successful, which made our synthetic
scheme of 13 lengthy.
With the fused heterocyclic cores 4, 8 and 13 in hand, the stage
was set for chain elongation. In our previous survey of reductive
amination conditions for analogous amines [10], NaBH(OAc)3 was
found to be a suitable reagent. Likewise, reaction of 4, 8 and 13
with the corresponding aldehydes gave all target compounds in
Fig. 4 Synthesis of compound 13. Reagents and conditions: a (i) BnOH,
NaH, THF (ii) MeI, K2CO3, DMF b (i) p-MPMNH2, Et3N, NMP (ii) H2, Pd/C,
MeOH c BrCH2CO2Me, K2CO3, DMF d (i) LDA, THF (ii) conc. HCl, MeOH
(iii) TFA.
moderate to good yields with the exception of 15d, due to insta-
▶
bility of 4d under the reaction conditions described in Fig. 5.
●
Sakairi M et al. Synthesis and Biological Evaluation… Arzneimittelforschung 2012; 62: 537–544

Original Article 543
Fig. 5 Synthesis of compounds 15–17. Reagents
and conditions: a (i) Corresponding alcohol, Dess-
martin periodinane, DCM (ii) NaBH(OAc)3, AcOH
(Method A) or DCM (Method B).
human and mouse respectively) with no significant hERG chan-
nel inhibition. The heterocyclic analogues 16a and 17a showed
somewhat improved agonistic activity for both type of receptors
with undetected levels of hERG channel inhibition, although the
pyridine analogue 17a seemed to have more potent agonistic
activity than the pyrimidine analogue 16a. This trend was also
observed with the N-tert-butoxycarbonyl analogues 16b and
17b. Based on these findings, 17a was chosen as starting point for
further optimization, which shifted to exploring the side chain.
Pioneering works have revealed productive substituents, such as
fluoro and methyl groups, around the side chains and indicated
their favorable topological location [6–8,14–19]. Taking this
information into account, we prepared compounds 17c–j with
Table 1 Test compounds agonistic activity for human and mouse GPR119
receptors, and their hERG channel inhibition.Table 1 Test compounds
agonistic activity for human and mouse GPR119 receptors, and their hERG
channel inhibition.
Compounds agonistic activityb for GPR119
the hope of improved agonistic activity for GPR119 receptors
▶
Human (nM)
Mouse (nM)
(
Table 2). Gratifyingly, acceptable levels of hERG channel inhi-
●
bition were observed with all compounds, suggesting that
6-aminofuro[3,2–c]pyridin-3(2H)-one may be a promising scaf-
fold for design of GPR119 agonists. Replacement of the ethyl
group in 17a by a methoxy, fluoro, or trifluoromethyl group (e.g.
17c–e) had no positive effects on the agonistic activity. Unlike
earlier observation that replacement of the piperidine moiety
with a constrained 7-azabicyclo[3.3.1]nonane ring enhances
GPR119 agonistic activity in the pyridin-3-yloxypyrimidine
series, significant loss in activity was observed with compounds
17f and 17g. Introduction of 3-isopropyl-1,2,4-oxadiazole, a
known surrogate for the pyrimidine moiety, also gave a slight
loss in activity, while 17h was equipotent with 17c–e. As our
exploration around the side chain terminus resulted in no
improvement, we moved to introduction of a methyl group adja-
cent to the terminal piperidine moiety. Compounds 17i and 17j
were thus prepared and tested. Fortunately, 17i showed 2-fold
improved activity with a human EC50 value of 14 nM. Also, this
subtle effect of the methyl group was observed with 17j with a
human EC50 value of 18 nM.
Com-
EC50
Emax
EC50
Emax
hERG inhibi-
tion (%)c
pound
1aa
51
58
78
113
110
115
167
160
54
110
109
110
97
14
21
NTd
NTd
NTd
0
1ba
15a
15b
15c
1ca
1098
114
52
110
117
94
1319
147
66
113
108
105
120
103
113
16a
16b
17a
17b
46
112
110
111
108
75
0
(26%)
31
513
45
3
0
(57%)
255
9
a Reported in ref [10]. b Values in parentheses indicate agonistic activity at 100μM.
Emax is %maximum, compared to the maximum response of AR231453. c Values
indicate %inhibition at 3μM in competitive hERG binding assay using 3H defetilide.
d Not tested
Biology
Results of test compounds biological evaluation are summarized
▶
in Table 1. In the aza-analogues of the parent compounds 1a
●
and 1b, compounds 15a–c showed reduced agonistic activity for
human GPR119, while 15a and 15c maintained agonistic acti-
vity for mouse GPR119. In the 6-aminobenzofuran-3(2H)-one
series, the parent compound 1c exhibited good agonistic activity
for both human and mouse GPR119 (EC50: 52 and 66 nMs in
W i t h 17i in hand, we briefly examined the effect of this com-
pound on gastric emptying, using acetaminophen absorption
method [10,11,20]. Fasted mice were treated with 10mg/kg of
17i, and 30min later with 100mg/kg of acetaminophen as a 2g/
kg glucose-containing aqueous solution. Plasma acetaminophen
Sakairi M et al. Synthesis and Biological Evaluation… Arzneimittelforschung 2012; 62: 537–544

544 Original Article
romatic rings, several heterocyclic cores were prepared and
6-aminofuro[3,2-c]pyridin-3(2H)-one was found as a promising
scaffold for GPR119 agonists. Further optimization around the
side chain moiety led to discovery of 17i, which showed not only
potent human GPR119 agonistic activity with EC50 value of
14nM, but also a delay gastric emptying and increase in total
plasma GLP-1 levels in mice.
Table 2 Optimized compounds agonistic activity for human and mouse
GPR119 receptors, and their hERG channel inhibition.
Conflict of Interest
▼
The authors report no conflict of interest.
References
Compounds agonistic activitya for GPR119
1 Lee MW, Fujioka K. Dietary prescriptions for the overweight patient:
the potential benefits of low-carbohydrate diets in insulin resistance.
Diabetes Obes Metab 2011; 13: 204–206
Human (nM)
mouse (nM)
Com-
EC50
Emax
EC50 Emax
hERG inhibi-
tion (%)b
2 Zinman B. Initial combination therapy for type 2 diabetes mellitus: is
it ready for prime time? Am J Med 2011; 124 (10): S19–S34
3 Gallwitz B. GLP-1 agonists and dipeptidyl-peptidase IV inhibitors. In:
Schwanstecher M (eds.). Handb Exp Pharmacol 2011; 203: 53–74
4 Overton HA, Fyfe MC, Reynet C. GPR119, a novel G protein-coupled
receptor target for the treatment of type 2 diabetes and obesity. Br J
Pharmacol 2008; 153 (S1): S76–S81
5 Jones RM, Leonard JN, Buzard DJ et al. GPR119 agonists for the treat-
ment of type 2 diabetes. Expert Opin Ther Pat 2009; 19: 1339–1359
6 Semple G, Fioravanti B, Pereira G et al. Discovery of the first potent
and orally efficacious agonist of the orphan G-protein coupled recep-
tor 119. J Med Chem 2008; 51: 5172–5175
pound
17c
17d
17e
17f
17g
17h
17i
64
106
111
94
126
70
104
98
0
51
0
NTc
51
30
72
N T c
(58%)
890
51
100
91
NTc
>10000
79
3
14
NTc
0
108
112
110
108
104
106
14
68
1
17j
18
61
0
7 Semple G, Ren A, Fioravanti B et al. Discovery of fused bicyclic ago-
nists of the orphan G-protein coupled receptor GPR119 with in vivo
activity in rodent models of glucose control. Bioorg Med Chem Lett
2011; 21: 3134–3141
aValues in parentheses indicate agonistic activity at 100μM. Emax is %maximum,
compared to the maximum response of AR231453. b Values indicate %inhibition at
3μM in competitive hERG binding assay using 3H defetilide. c Not tested
8 Mascitti V, Stevens BD, Choi C et al. Design and evaluation of a
2-(2,3,6-trifluorophenyl)acetamide derivative as an agonist of the
GPR119 receptor. Bioorg Med Chem Lett 2011; 21: 1306–1309 and
the current status of development of MBX-2982 and GSK-1292263
are cited therein
9 Reported values of human GPR119 agonist potency for these drug
candidates are as follows: APD668, 2.7nM; MBX-2982, 3.9nM;
GSK1292263, 126nM
Table 3 E ffects of 17i on gastric emptying and plasma levels of total
GLP-1a
Plasma acetaminophen conc. (mM)
total GLP-1
(pM)b
10min
20min
AUC0−20min
30min
10 Sakairi M, Kogami M, Torii M et al. Synthesis and SAR studies of bicy-
clic amine series GPR119 agonists. Bioorg Med Chem Lett 2012; 22:
5123–5128
(mM·min)
Control 0.355±0.019
17i
0.364±0.013
5.38±0.23
4.40±0.72
11 Sakairi M, Kogami M, Torii M et al. Synthesis and pharmacological profile
of a new selective G protein-coupled receptor 119 agonist; 6-((2-Fluoro-
3-(1-(3-isopropyl-1,2,4-oxadiazol-5-yl)piperidin-4-yl)propyl)amino)-
2,3-dihydro-1H-inden-1-one. Chem Pharm Bull Jpn 2012 in press
12 Jamieson C, Moir EM, Rankovic Z et al. Medicinal chemistry of hERG opti-
mizations: Highlights and hang-ups. J Med Chem 2006; 49: 5029–5046
13 Brown SP, Dransfield P, Du X et al. Spirocyclic GPR40 modulators.
WO2010/045258 (A2)
0.263±0.022** 0.284±0.018*** 4.05±0.30** 9.76±0.65***
aStatistical significance was tested using one-way ANOVA and Dunnett multiple com-
parison test. **, p<0.01 vs. vehicle control.***, p<0.001 vs. vehicle control. Data are
expressed as the mean±SEM. b Determined by ELISA 30min after administration
concentrations were determined at 10 and 20min after acetami-
14 Dominique R, Pietranico S, Guertin K et al. Discovery of GPR119 ago-
nists for the treatment of Type 2 Diabetes: Part 2. Dihydropyrrolopy-
rimidines. the American chemical society 239th annual meetings, San
Francisco, CA; March 2010
15 George K, Zhang Q, Pietranico S et al. Discovery of GPR119 agonists for
the treatment of Type 2 Diabetes: Part 1. Dihydropyrrolopyrimidines.
the American chemical society 239th annual meetings, San Francisco,
CA; March 2010
16 Wu Y, Kuntz JD, Carpenter AJ et al. 2,5-Disubstituted pyridines as
potent GPR119 agonists. Bioorg Med Chem Lett 2010; 20: 2577–2581
17 McClure KF, Darout E, Guimarães CR et al. Activation of the G-protein-
coupled receptor 119: a conformation-based hypothesis for under-
standing agonist response. J Med Chem 2011; 54: 1948–1952
18 Szewczyk JW, Acton J, Adams AD et al. Design of potent and selective
GPR119 agonists for type II diabetes. Bioorg Med Chem Lett 2011;
21: 2665–2669
nophen oral administration. Compound 17i produced a signifi-
cant decrease in acetaminophen plasma levels at both time
▶
points, indicating a delay in gastric emptying ( Table 3). These
●
encouraging results on gastric emptying led us to further examine
plasma levels of total GLP-1. Thus, fasted mice were orally treated
with 30mg/kg of 17i as an aqueous suspension and plasma total
GLP-1 levels were assayed by ELISA. 17i produced a significant
increase in plasma total GLP-1 levels 30min after treatment,
while no significant change was observed in the vehicle control
compared to pretreatment baseline (data not shown). These find-
ings suggest that 17i has acceptable potential as GPR119 agonist.
19 Xia Y, Chackalamannil S, Greenlee WJ et al. Discovery of a nortropanol
derivative as a potent and orally active GPR119 agonist for type 2
diabetes. Bioorg Med Chem Lett 2011; 21: 3290–3296
20 Flock G, Holland D, Seino Y et al. GPR119 regulates murine glucose
homeostasis through incretin receptor-dependent and independent
mechanisms. Endocrinology 2011; 152: 374–383
Conclusion
▼
In summary, based on a strategy for attenuating the basicity of
the nitrogen atom of the parent compound 1a by replacing
the adjacent benzene ring with electron-deficient heteroa-
Sakairi M et al. Synthesis and Biological Evaluation… Arzneimittelforschung 2012; 62: 537–544