Design and synthesis of a pyrido[2,3-d]pyrimidin-5-one class of anti-inflammatory FMS inhibitors

Article abstract of DOI:10.1016/j.bmcl.2008.02.070

A series of pyrimidinopyridones has been designed, synthesized and shown to be potent and selective inhibitors of the FMS tyrosine kinase. Introduction of an amide substituent at the 6-position of the pyridone core resulted in a significant potency increase. Compound 24 effectively inhibited in vivo LPS-induced TNF in mice greater than 80%.

Full text of DOI:10.1016/j.bmcl.2008.02.070

Available online at www.sciencedirect.com
Bioorganic & Medicinal Chemistry Letters 18 (2008) 2355–2361
Design and synthesis of a pyrido[2,3-d]pyrimidin-5-one class
of anti-inflammatory FMS inhibitors
Hui Huang, Daniel A. Hutta, Huaping Hu, Renee L. DesJarlais, Carsten Schubert,
Ioanna P. Petrounia, Margery A. Chaikin, Carl L. Manthey and Mark R. Player*
Johnson & Johnson Pharmaceutical Research & Development, Welsh & McKean Roads, Spring House, PA 19477, USA
Received 23 January 2008; revised 26 February 2008; accepted 27 February 2008
Available online 4 March 2008
Abstract—A series of pyrimidinopyridones has been designed, synthesized and shown to be potent and selective inhibitors of the
FMS tyrosine kinase. Introduction of an amide substituent at the 6-position of the pyridone core resulted in a significant potency
increase. Compound 24 effectively inhibited in vivo LPS-induced TNF in mice greater than 80%.
Ó 2008 Elsevier Ltd. All rights reserved.
Increased tumor-associated macrophage numbers have
been associated with tumor progression.1 In addition,
O
5
N
3N
OEt
6
macrophage numbers present within target tissues have
been strongly correlated with disease severity in rheuma-
toid arthritis,2 and immune nephritis.3 In some solid tu-
mors, such as breast cancer, elevated macrophage
numbers are thought to contribute to disease progres-
sion and poor survivability.4–6 The proliferation and
survival of macrophages, monocytes, and their progeni-
tors are driven by macrophage colony-stimulating factor
(M-CSF or CSF-1).7 Binding of CSF-1 to its exclusive
receptor, colony-stimulating factor-1 receptor (FMS),
induces receptor dimerization and autophosphorylation
which leads to the phosphorylation of downstream sig-
naling proteins, and the subsequent differentiation and
activation of cells in the macrophage lineage.8 Animal
studies with CSF-1 deficient mice suggest that CSF-1/
FMS is a crucial component of a positive cycle that
drives chronic inflammation.9–11 Thus, the inhibition
of FMS has great potential in treating human diseases
such as rheumatoid arthritis as well as certain cancers
where macrophages are pathogenic.
2
N
N
N 8
O
IC50= 0.18 μM
H
1
Figure 1. High-throughput screening hit 1.
small set of these pteridinones was synthesized and it
was observed that replacement of the N-8 phenyl of 1
with an indan ring resulted in a 10-fold potency increase
(data not shown).
Compound 1 was modeled in FMS (PDB ID: 2i0y)13 in
order to evaluate the interactions required for binding
(Fig. 2). Related pyrido[2,3-d]pyrimidin-7-one kinase
inhibitors have previously been shown to interact with
the hinge region via hydrogen bonds to the amino NH
and N-3 of the pyrimidine ring.14 The model was built
assuming similar interactions for the amino NH and
the pteridinone N-3 of hit 1 with, respectively, the back-
bone carbonyl and backbone NH of the hinge residue
Cys666. In addition, the following interactions were pre-
dicted by this model: a hydrogen bond between the side-
chain hydroxyl of Thr663 and the pteridinone N-5, a
hydrogen bond between either the pteridinone carbonyl
or the ester carbonyl and the terminal amine of Lys616
(depending on side chain conformation), and hydropho-
bic interactions for the N-8 phenyl.
By screening a focused kinase library using Thermoflu-
orÒ technology,12 pteridinone 1 was identified as a con-
firmed hit with an IC50 of 0.18 lM for FMS (Fig. 1). A
Keywords: FMS; cFMS; Colony-stimulating factor-1 receptor; CSF-1;
M-CSF; Macrophage; Pyrimidinopyridone.
*
Corresponding author. Tel.: +1 610 458 6980; fax: +1 610 458
8258; e-mail: mplayer@prdus.jnj.com
0960-894X/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2008.02.070

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H. Huang et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2355–2361
line by nucleophilic substitution. The resulting carboxyl-
ate ester 2 was converted to the carboxylic acid 8 by
hydrolysis, or to the amides 9 and 11–34 by reaction
with the corresponding amines in methanol in a pressure
bottle.
Compound 10, where N-1 was replaced with CH, was
synthesized by the methods shown in Scheme 2. 4,6-
Dihydroxynicotinic acid ethyl ester 35 was obtained in
two steps from diethyl 1,3-acetonedicarboxylate.16
Treatment of 35 with phosphorous oxychloride gave
4,6-dichloronicotinic acid ethyl ester 36. The subsequent
nucleophilic displacement yielding 37 and Dieckmann
cyclization followed by halogenation/dehydrohalogen-
ation which yielded 38 were similar to the methods out-
lined in Scheme 1. Substitution of the 2-position
chloride of 38 with the piperazinyl aniline was carried
out under microwave conditions to afford ethyl ester
39, which was then converted to the amide 10 by treat-
ment with methanolic ammonia.
Figure 2. Model of 1 (cyan carbons) in FMS kinase (white carbons).
Hydrogen bonds and potential hydrogen bonds are shown as green
and magenta dotted lines, respectively.
All compounds were tested in an in vitro enzyme assay
for their abilities to inhibit ATP-induced auto-phos-
phorylation of FMS (Tables 1 and 2).17 The most potent
compounds were also tested in a functional assay, which
was based upon inhibition of CSF-1 driven proliferation
of bone marrow-derived macrophages (BMDM).18 In
this cell-based assay, compound 2 was moderately active
with an IC50 value of 0.47 lM. According to the model,
the C-2 anilino substituents are largely solvent-exposed.
It seemed likely that the C-6 carboxylate ester and N-8
hydrophobic substitutions would be more important in
terms of binding at the active site due to their more inti-
mate contact with the protein. Thus, the C-2 substitu-
tion was initially fixed as 4-(4-methyl-piperazin-1-yl)-
phenylamine, while the C-6 and N-8 positions were ex-
plored (Table 1). The C-6 carboxylic acid 8 was about
fourfold less active, whereas transformation of the ester
to primary amide 9 resulted in a significant increase in
potency. The model of 9 in FMS suggested that the
amide could make an intramolecular hydrogen bond
to the C-5 carbonyl stabilizing a conformation of the
molecule that optimizes hydrogen bonding between the
amide carbonyl and the terminal amine of Lys616. The
model does not predict that N-1 of the pyrimidine ring
is making a direct interaction with FMS. However, re-
moval of N-1 as in 10 decreased potency about fourfold.
The greater potency of 9 is likely due to the lower basi-
city of the aminopyrimidine system, which favors the
neutral form of the molecule necessary for interaction
with Cys666.
Based on this model of pteridinone binding, novel scaf-
folds were explored in an attempt to improve potency.
One of the most promising designs was constructed
from a 5,8-dihydro-pyrido[2,3-d]pyrimidin-5-one scaf-
fold. Represented by 2 (Fig. 3), this scaffold was pre-
dicted to bind with a minimal shift of the ring system
away from Thr663. With an IC50 of 0.25 lM for FMS,
2 showed a 10-fold potency loss compared to its pterid-
inone analogue (IC50 = 0.02 lM). A detailed SAR study
was then conducted to improve its in vitro potency.
Herein, the structure–activity relationships at three
areas of the new scaffold are reported: the C-6 carboxyl-
ate ester, N-8 hydrophobic substitution and C-2 anilino
substitution.
A linear synthetic method was developed to quickly
synthesize analogues of 2 (Scheme 1). An amine, for
example, indan-5-ylamine, was reacted with ethyl
3-chloropropionate at elevated temperature in the pres-
ence of an inorganic base and a catalytic amount of tet-
rabutylammonium
bromide
to
afford
the
aminopropionate ester 3, which was treated with ethyl
4-chloro-2-methylthio-5-pyrimidinecarboxylate to pro-
duce the 4-substituted aminopyrimidine 4. Cyclization
of this diester under Dieckmann conditions afforded
bicyclic compound 5. Subsequent halogenation with
bromine followed by dehydrohalogenation gave 6.15
The thiomethyl moiety was oxidized to the sulfone 7,
which was subsequently displaced with an amine or ani-
Small alkyl substitution on the C-6 amide was well tol-
erated, though activity diminished with increasing size
of the alkyl group (11, 12). The N-8 substituents occupy
a hydrophobic pocket of the active site. Whereas ali-
phatic rings (13–15) maintained activity, the unsubsti-
tuted phenyl compound 16 significantly attenuated
potency. This trend also had been observed within the
pteridinone high-throughput screening hit series. Ben-
zylic substitution (17) also resulted in a potency de-
O
O
N
N
N
OEt
6
8
N
2
N
H
N
IC50= 0.25 μM
2
crease, although to
substitution.
a lesser extent than phenyl
Figure 3. A novel 5,8-dihydro-pyrido[2,3-d]pyrimidin-5-one scaffold
represented by 2.

H. Huang et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2355–2361
2357
CO2Et
N
CO2Et
b
a
HN
NH2
CO2Et
c
S
N
N
CO2Et
Cl
N
4
3
S
N
O
N
O
N
O
N
CO2Et
CO2Et
CO2Et
N
N
f
g
N
S
d,e
S
N
S
N
N
O
O
6
7
5
N
O
N
N
O
N
O
N
N
CO2Et
i
NHMe
N
N
N
H
N
N
H
N
2
11
h
N
O
N
CO2H
N
N
8
N
H
N
Scheme 1. Reagents and conditions: (a) Ethyl 3-chloropropionate, K2CO3, Bu4NBr (cat.), 100 °C, 71%; (b) Et3N, n-BuOH, rt, 90%; (c) t-BuONa,
toluene, 90 °C, 62%; (d) Br2, CH2Cl2, rt; (e) Et3N, CH2Cl2, rt, 94%; (f) m-CPBA, CH2Cl2, rt, 67%; (g) 4-(4-methyl-piperazin-1-yl)-phenylamine, i-
PrOH, 90 °C, 61%; (h) NaOH, THF, 50 °C, 60%; (i) methylamine, MeOH, rt or 70 °C.
The model predicts that the C-2 anilino NH hydrogen
bonds to the protein backbone and the phenyl ring occu-
pies a narrow hydrophobic pocket. Although the sub-
stituents at the para or meta positions of the aniline
ring are predicted to be solvent-exposed, they did have
an effect on activity, as was demonstrated by the potency
loss of 18 versus 9. In addition, this region provided a
solubilizing handle for the chemotype. There were no
protein backbone contacts in this solvent-exposed re-
gion which could adequately explain the changes in po-
tency afforded by different polar substitutions on the
aniline ring. Therefore, an extensive search for an opti-
mal C-2 substituent was carried out with C-6 fixed as
a primary amide and N-8 as indan (Table 2).
the 4-methylpiperazine and the phenyl ring did not affect
the inhibitory activity (9, 24 and 25), although the
microsomal stability of the compounds was impacted.
With a one-carbon linker, 24 was the least stable com-
pound among the three in both rat liver microsomes
(RLMs) and human liver microsomes (HLMs) (Table
3). The same trend was observed with morpholino (26,
27) and dimethylamino analogues (28, 29). Small modi-
fications of the piperazine ring (19–21, 23) had little
influence on the activity. The compounds with neutral
substituents (30, 31) showed similar activities as those
with basic ones, but had poorer solubility. When the
C-2 substituents were derived from aliphatic amines
(32–34) as opposed to anilines, the activities markedly
diminished. This is probably due to the narrow-binding
pocket geometry that is better accommodated by flat
planar groups.
Excellent activity was observed among the 3- or 4-
substituted aniline analogues (9, 19–31) in both the
in vitro enzyme and the BMDM assays. With a 2-hydro-
xyl substitution, 22 showed a slight potency decline rel-
ative to 9. Introduction of small alkyl linkers between
Because of its excellent BMDM activity, the binding
mode of 20 was analyzed using X-ray crystallography.

2358
H. Huang et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2355–2361
O
CO2Et
OH
CO2Et
Cl
N
N
c
CO2Et
a, b
EtO2C
HO
Cl
36
35
O
CO2Et
N
CO2Et
e, f, g
d
N
CO2Et
h
Cl
N
3
Cl
N
37
38
O
N
O
N
N
O
N
N
CO2Et
N
N
NH2
i
N
H
N
N
H
39
10
Scheme 2. Reagents and conditions: (a) Trimethylorthoformate, Ac2O, 120 °C; (b) NH4OH, rt; (c) POCl3, 100 °C, 68%; (d) Et3N, DMF, 100 °C,
44%; (e) t-BuONa, toluene, 90 °C; (f) Br2, CH2Cl2, rt; (g) Et3N, CH2Cl2, rt, 34%; (h) 4-(4-methyl-piperazin-1-yl)-phenylamine, Et3N, NMP,
microwave irradiation, 200 °C, 18%; (i) NH3, MeOH, rt, 65%.
Table 1. 6- and 8-Position modifications to the 5,8-dihydro-pyrido[2,3-d]pyrimidin-5-one series
N
O
O
N
N
R2
N
H
X
N
R1
2-17
R1
R2
Auto-Pi IC50 (lM)
BMDM IC50 (lM)
a
b
Compound
X
2
8
N
N
N
C
Indan-5-yl
Indan-5-yl
Indan-5-yl
Indan-5-yl
Indan-5-yl
Indan-5-yl
Cyclohexyl
Cyclopentyl
OEt
OH
0.25
1.1
0.47
ND
0.016
ND
ND
ND
ND
ND
ND
ND
ND
9
NH2
NH2
NHMe
NHEt
NH2
NH2
NH2
NH2
NHMe
0.013
0.056
0.031
0.068
0.035
0.056
0.081
0.73
10
11
12
13
14
15
16
17
N
N
N
N
N
N
N
Bicyclo[2.2.1]hept-2-yl
Phenyl
Benzyl
0.42
a Reported IC50 values are means of three experiments. Inter-assay variance was <10%.
b Dose–response data are the average of at least two replicates per dose.
Like all previously analyzed FMS inhibitors,19 20 is lo-
cated in the ATP binding pocket (Fig. 4A). Consistent
with the aforementioned model, this series interacts with
the hinge region of the kinase via crucial hydrogen-
bonding interactions mediated through the C-2 amino
NH and the pyrimidine N-3 (Fig. 4). Like the N-5 of
the pteridinones, the C-5 carbonyl oxygen of the 5,8-
dihydro-pyrido[2,3-d]pyrimidin-5-one forms a hydrogen
bond with the hydroxyl group of Thr663.
distinguished by crystallographic means. However,
based on an analysis of the hydrogen-bonding patterns
for both rotamers of the amide, the depicted rotamer
is proposed to be the favored orientation. Here the
amide is engaged in an intramolecular hydrogen bond
with the C-5 carbonyl oxygen (Fig. 4, magenta), thereby
stabilizing a flat conformation of the pyrimidinopyri-
done core and positioning the amide carbonyl for its
interaction with Lys616. Furthermore, the amide-nitro-
gen is also part of a water-mediated hydrogen-bonding
network, which includes the hydroxyl group of
Thr663, the C-5 carbonyl oxygen and two water mole-
Since the oxygen and NH of the terminal amide share
the same number of electrons, their position cannot be

H. Huang et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2355–2361
Table 2. 2-Position modifications to the 5,8-dihydro-pyrido[2,3-d]pyrimidin-5-one series
2359
O
O
N
NH2
R3
N
H
N
N
18-34
a
b
Compound
R3
Auto-Pi IC50 (lM)
BMDM IC50 (lM)
18
9
Phenyl
4-(4-Methyl-piperazin-1-yl)-phenyl
4-Piperazin-1-yl-phenyl
0.28
ND
0.013
0.005
0.007
0.008
0.093
0.008
0.014
0.008
0.022
0.008
0.021
0.003
0.004
0.012
3.3
0.016
0.004
0.003
0.006
ND
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
4-(3,5-Dimethyl-piperazin-1-yl)-phenyl
3-(4-Methyl-piperazin-1-yl)-phenyl
2-Hydroxy-4-(4-methyl-piperazin-1-yl)-phenyl
4-Piperidin-4-yl-phenyl
0.051
0.011
0.009
0.027
0.008
0.004
0.016
0.014
0.09
4-(4-Methyl-piperazin-1-ylmethyl)-phenyl
4-[2-(4-Methyl-piperazin-1-yl)-ethyl]-phenyl
4-Morpholin-4-ylmethyl-phenyl
4-(2-Morpholin-4-yl-ethyl)-phenyl
4-Dimethylaminomethyl-phenyl
4-Dimethylaminoethyl-phenyl
3-(Piperidin-1-yl-methanone)phenyl
S-4-[4-(Oxazolidin-2-one)-methyl]-phenyl
2-Morpholin-4-yl-ethyl
ND
ND
3-(4-Methyl-piperazin-1-yl)-propyl
3-Imidazol-1-yl-propyl
1.8
2.3
ND
a Reported IC50 values are means of three experiments. Inter-assay variance was <10%.
b Dose–response data are the average of at least two replicates per dose.
cules present in close proximity. The co-crystal structure
confirmed the modeling predictions and provided the
structural basis for further lead optimization within this
series.
tion of control-specific binding greater than 50% at a
concentration of 10 lM. These were human A2A and
A3 with 60% and 58% inhibition, respectively.
Due to their desirable in vitro properties, compound 9
and 24 were profiled for their pharmacokinetic (PK)
properties in the rat. After an intravenous injection at
2 mg/kg, 9 showed very high clearance (CL = 133 mL/
min/kg) and a high volume of distribution (Vd =
18.7 L/kg). After an oral dose of 10 mg/kg, the plasma
concentrations of 9 were below detectable levels. The
PK profile of 24 was not significantly improved, with
high clearance (CL = 29 mL/min/kg) and high volume
of distribution (Vd = 26.5 L/kg). Compound 24 exhib-
ited low oral bioavailability (4%).
FMS is a member of the type III receptor tyrosine ki-
nases that also includes FLT-3, PDGFR-b and KIT. Ta-
ble 4 shows the kinase selectivity of compound 9 and 24.
Both are potent inhibitors of FLT-3 and KIT, but
highly selective over PDGFR-b, Axl, IRK-b and Src.
They inhibited the neurotrophic type I tyrosine kinase
receptor, TrkA with modest potency. To further evalu-
ate specificity, compound 9 and 24 were assessed in a
standard counterscreening panel of fifty receptors, trans-
porters and ion channels (data not shown). At a concen-
tration of 5 lM, 9 inhibited human A3 binding at 55%
with no other assays showing greater than 50% inhibi-
tion. In the case of 24, only two assays indicated inhibi-
Administration of FMS inhibitors was shown previously
to inhibit LPS-induced TNFa in mice.20 To examine the
in vivo activity of 24, groups of eight male Swiss Web-
ster mice were administered vehicle (20% hydroxpro-
pyl-b-cyclodextrin) or 24 at 20 or 50 mg/kg by the
intraperitoneal route. Three hours later saline or LPS
(100 lg/kg) in saline was administered via the tail vein.
TNFa was measured by ELISA (R&D Systems) in plas-
ma harvested by cardiac puncture from mice euthanized
90 min after the LPS dose. Compound 24 at 20 and
50 mg/kg inhibited LPS-induced TNFa by 81% and
87%, respectively (Table 5).
Table 3. The effect of alkyl chain length on microsomal stability
Compound
HLMa
RLMa
9
24
25
26
27
28
29
80.5
74
87.3
54
96
84
2.5
58
9.7
83
35
88
38
65
a Percent remaining 10 min after incubating the compounds with liver
microsomes.
In conclusion, a novel series of 5,8-dihydro-pyrido[2,3-
d]pyrimidin-5-ones was designed and synthesized as

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H. Huang et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2355–2361
Table 5. Compound 24 inhibits in vivo LPS-induced TNFa
Pretreatmenta
Challengeb
TNFac (pg/ml)
Vehicle
Vehicle
Saline
LPS
LPS
12 (5)
3688 (566)
687 (80)*
499 (61)*
Compound 24, 20 mg/kg
Compound 24, 50 mg/kg
LPS
a Mice were predosed by intraperitoneal injection with vehicle or 24
three hours prior to LPS challenge.
b Saline or 100 lg/kg LPS (Sigma, 0127:B8) via tail vein.
c Mean (SEM) plasma TNFa 90 min after challenge.
* p < 0.01 versus vehicle plus LPS.
mechanism of FMS inhibition and serves as a lead series
for further optimization.
References and notes
1. Chen, J. J. W.; Lin, Y. C.; Yao, P. L.; Yuan, A.; Chen, H.
Y.; Shun, C. T.; Tsai, M. F.; Chen, C. H.; Yang, P. C. J.
Clin. Oncology 2005, 23, 953.
2. Yanni, G.; Whelan, A.; Feighery, C.; Bresnihan, B. Ann.
Rheum. Dis. 1994, 53, 39.
3. (a) Yang, N.; Isbel, N. M.; Nikolic-Paterson, D. J.; Li, Y.;
Ye, R.; Atkins, R. C.; Lan, H. Y. Kidney Int. 1998, 54,
143; (b) Isbel, N. M.; Nikolic-Patterson, D. J.; Hill, P. A.;
Dowling, J.; Atkins, R. C. Nephrol. Dial. Transplant. 2001,
16, 1638.
4. Kluger, H. M.; Dolled-Filhart, M.; Rodov, S.; Kacinski,
B. M.; Camp, R. L.; Rimm, D. L. Clin. Cancer Res. 2004,
10, 173.
Figure 4. Close-up view of the ligand-binding site. (A) Ball-and-stick
representation of 20 (yellow carbons) bound in the active site of FMS
(grey carbons). Hydrogen bonds to the backbone of the protein and
within the water-network are depicted as green dashed lines and the
internal hydrogen-bond between the amide nitrogen and the C5
carbonyl oxygen is drawn in magenta. (B) Ball-and-stick representa-
tion of 20 in a 2fo-fc electron density map (blue) contoured at 1.4r and
truncated to a radius of 2 A beyond each atom for clarity. Also drawn
is a fo-fc electron density map contoured to 3r (green) and -3r (red),
˚
truncated beyond 3 A. (PDB ID: 3BEA).
5. Lin, E. Y.; Nguyen, A. V.; Russell, R. G.; Pollard, J. W. J.
Exp. Med. 2001, 193, 727.
˚
6. Yee, L. D.; Liu, L. Anticancer Res. 2000, 20, 4379.
7. Sherr, C. J. Biochim. Biophys. Acta 1988, 948, 225.
8. (a) Pixley, F. J.; Stanley, E. R. Trends Cell Biol. 2004, 14,
628; (b) Sherr, C. J.; Roussel, M. F.; Rettenmier, C. W. J.
Cell. Biochem. 1988, 38, 179.
9. Campbell, I. A.; Rich, M. J.; Bischof, R. J.; Hamilton, J.
A. J. Leukocyte Biol. 2000, 68, 144–150.
10. Pollard, J. W.; Stanley, E. R. Adv. Dev. Biochem. 1995, 4,
153.
Table 4. IC50 data of compound 9 and 24 in a kinase counterscreen
Kinase
9a (lM)
24a (lM)
11. Van Wesenbeeck, L.; Odgren, P. R.; MacKey, C. A.;
D’Angelo, M.; Safadi, F. F.; Popoff, S. N.; Van Hul, W.;
Marks, S. C., Jr. PNAS 2002, 99, 14303.
12. Carver, T. E.; Bordeau, B.; Cummings, M. D.; Petrella, E.
C.; Pucci, M. J.; Zawadzke, L. E.; Dougherty, B. A.;
Tredup, J. A.; Bryson, J. W.; Yanchunas, J., Jr.; Doyle,
M. L.; Witmer, M. R.; Nelen, M. I.; DesJarlais, R. L.;
Jaeger, E. P.; Devine, H.; Asel, E. D.; Springer, B. A.;
Bone, R.; Salemme, F. R.; Todd, M. J. J. Biol. Chem.
2005, 280, 11704.
13. Schubert, C.; Schalk-Hihi, C.; Struble, G. T.; Ma, H. C.;
Petrounia, I. P.; Brandt, B.; Deckman, I. C.; Patch, R. J.;
Player, M. R.; Spurlino, J. C.; Springer, B. A. J. Biol.
Chem. 2007, 282, 4094.
14. Berman, H. M.; Westbrook, J.; Feng, Z.; Gilliland, G.;
Bhat, T. N.; Weissig, H.; Shindyalov, I. N.; Bourne, P. E.
Nuc. Acids Res. 2000, 28, 235.
FMS
FLT-3
KIT
0.013
0.003
0.056
>1
0.014
0.001
0.028
>2
PDGFR-b
Axl
>0.3
0.2
>0.5
0.31
>2
TrkA
IRK-b
Src
>1
1
1.5
a IC50 values were determined at the respective ATP Km for each
kinase.
inhibitors of FMS. Conversion of the C-6 carboxylic es-
ter of 2 to a primary amide as in 9, led to a significant
increase in inhibitory potency. The structural basis for
this enhanced activity was provided by the co-crystal
structure of 20 in FMS. The exceptional in vitro potency
of this series translated into robust in vivo activity of 24
as demonstrated by inhibition of LPS-induced TNFa in
mice. Although 24 and 9 suffered from poor oral PK,
this series provided novel structural insight into the
15. Barvian, M.; Boschelli, D. H.; Cossrow, J.; Dobru-
sin, E.; Fattaey, A.; Fritsch, A.; Fry, D.; Harvey,
P.; Keller, P.; Garrett, M.; La, F.; Leopold, W.;
McNamara, W.; Quin, M.; Trumpp-Kallmeyer, S.;
Toogood, P.; Wu, Z.; Zhang, E. J. Med. Chem.
2000, 43, 4606.

H. Huang et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2355–2361
2361
16. Pesson, M.; Antoine, M.; Chabassier, S.; Geiger, S.;
Girard, P.; Richer, D.; De Lajudie, P.; Horvath, E.;
Leriche, B.; Patte, S. Eur. J. Med. Chem. 1974, 9, 585.
17. Ruesdale, L. K.; Sherbine, J. P.; Vanasse, B. J. PCT Int.
Appl. (1997), WO9724327A1.
18. Schalk-Hihi, C.; Ma, H. C.; Struble, G. T.; Bayoumy, S.;
Williams, R.; Devine, E.; Petrounia, I. P.; Mezzasalma, T.;
Zeng, L.; Schubert, C.; Grasberger, B.; Springer, B. A.;
Deckman, I. C. J. Biol. Chem. 2007, 282, 4085.
19. Patch, R. J.; Brandt, B. M.; Asgari, D.; Baindur, N.;
Chadha, N. K.; Georgiadis, T.; Cheung, W. S.; Petrounia,
I. P.; Donatelli, R. R.; Chaikin, M. A.; Player, M. R.
Bioorg. Med. Chem. Lett. 2007, 17, 6070.
20. Conway, J. G.; McDonald, B.; Parham, J.; Keith, B.; Rusnak,
D. W.; Shaw, E.; Jansen, M.; Lin, P.; Payne, A.; Crosby, R.
M.; Johnson, J. H.; Frick, L.; Lin, M. H. J.; Depee, S.;
Tadepalli, S.; Votta, B.; James, I.; Fuller, K.; Chambers, T. J.;
Kull, C. K. Proc. Natl. Acad. Sci. 2005, 102, 16078.