Fused bicyclic derivatives of 2,4-diaminopyrimidine as c-Met inhibitors

Article abstract of DOI:10.1016/j.bmcl.2010.11.045

The HGF-c-Met signaling axis is an important paracrine mediator of epithelial-mesenchymal cell interactions involving the regulation of multiple cellular activities including cell motility, mitogenesis, morphogenesis, and angiogenesis. Dysregulation of c-Met signaling (e.g., overexpression or increased activation) is associated with the development of a wide range of tumor types; thus, inhibiting the HGF-c-Met pathway is predicted to lead to anti-tumor effects in many cancers. Elaboration of a 2-arylaminopyrimidine scaffold led to a series of potent c-Met inhibitors bearing a C4-2-amino-N-methylbenzamide group. Specifically, a series of C2-benzazepinone analogs demonstrated potent inhibition of c-Met in enzymatic and cellular assays. Kinase selectivity could be tuned by varying the nature of the alkyl group on the benzazepinone nitrogen.

Full text of DOI:10.1016/j.bmcl.2010.11.045

Bioorganic & Medicinal Chemistry Letters 21 (2011) 164–167
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Fused bicyclic derivatives of 2,4-diaminopyrimidine as c-Met inhibitors
⇑
Linda R. Weinberg , Mark S. Albom, Thelma S. Angeles, Jean Husten, Joseph G. Lisko, Robert J. McHugh,
Karen L. Milkiewicz, Seetha Murthy, Gregory R. Ott, Jay P. Theroff, Rabindranath Tripathy, Ted L. Underiner,
Craig A. Zificsak, Bruce D. Dorsey
Worldwide Discovery Research, Cephalon, Inc., 145 Brandywine Parkway, West Chester, PA 19380-4245, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
The HGF-c-Met signaling axis is an important paracrine mediator of epithelial–mesenchymal cell
interactions involving the regulation of multiple cellular activities including cell motility, mitogenesis,
morphogenesis, and angiogenesis. Dysregulation of c-Met signaling (e.g., overexpression or increased
activation) is associated with the development of a wide range of tumor types; thus, inhibiting the
HGF-c-Met pathway is predicted to lead to anti-tumor effects in many cancers. Elaboration of a 2-aryla-
minopyrimidine scaffold led to a series of potent c-Met inhibitors bearing a C4-2-amino-N-methylbenza-
mide group. Specifically, a series of C2-benzazepinone analogs demonstrated potent inhibition of c-Met
in enzymatic and cellular assays. Kinase selectivity could be tuned by varying the nature of the alkyl
group on the benzazepinone nitrogen.
Received 30 September 2010
Revised 4 November 2010
Accepted 8 November 2010
Available online 11 November 2010
Keywords:
c-Met
Kinase inhibitors
Mesenchymal epithelial transition factor
Diaminopyrimidine
Ó 2010 Elsevier Ltd. All rights reserved.
Mesenchymal epithelial transition factor (c-Met) kinase and its
natural ligand, hepatocyte growth factor (HGF) are involved in sig-
naling pathways for embryological development, wound healing,
tissue regeneration, angiogenesis, proliferation, survival, scatter-
ing, and morphogenic differentiation. The pathway regulates a ser-
ies of intracellular downstream events in many different cell types
that lead to cell growth, motility, and invasion.
Due to the c-Met/HGF role of regulation of cellular motility,
cells expressing high levels of HGF and/or c-Met are likely to be
metastatic.1,2 The cells can become solid tumors in the liver, breast,
pancreas, lung, kidney, bladder, ovary, brain, prostate, and
gallbladder.1,2
In general, these diaminopyrimidine targets were prepared by
first coupling 2-aminobenzamide analogs 2, derived from the cor-
responding isatoic anhydrides 1, with trichloropyrimidine to afford
aminopyrimidines 3; these intermediates were then coupled to
aminobenzazepin-2-ones 4 or 5 (Scheme 1).
Aminobenzazepin-2-one isomers (4 and 5) were prepared as
described in Schemes 2 and 3. Beckmann rearrangement of the
oxime derived from tetralone 6 produced benzazepinone 8.5 Nitra-
tion of 8a or 8b followed by either reduction or alkylation and
reduction afforded intermediates 4a–d.
A number of Type I (DFG-in) and Type II (DFG-out) c-Met inhibi-
tors are currently being evaluated clinically and several Type I inhib-
itors which are currently in clinical trials are shown in Figure 1.3
In connection with other work focused on optimizing a 2,4-dia-
minopyrimidine scaffold to inhibit ALK, it was discovered that
compounds with an aminobenzamide appended at C4 consistently
demonstrated potent c-Met inhibition (Fig. 2).4,5 This putative Type
I kinase inhibitor platform served as a starting point in a medicinal
chemistry effort to optimize c-Met cellular activity while improv-
ing overall kinase selectivity. This Letter describes the synthesis
and c-Met SAR around a series of diaminopyrimidine analogs bear-
ing a C4-aminobenzamide and a C2-benzazepinone substituent
and how kinase selectivity can be tuned by varying the nature of
these appendages (Fig. 2).
⇑
Corresponding author. Tel.: +1 610 738 6595.
E-mail address: lweinber@cephalon.com (L.R. Weinberg).
Figure 1. Type I c-Met inhibitors in clinical trials.
0960-894X/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2010.11.045

L. R. Weinberg et al. / Bioorg. Med. Chem. Lett. 21 (2011) 164–167
165
Figure 2. Diaminopyrimidine kinase inhibitor scaffold.
Scheme 3. Synthesis of 8-amino-1,3,4,5-tetrahydro-benzo[b]azepin-2-one (5).
Reagents and conditions: (a) H2SO4, HNO3; (b) NaOAc, NH2OHꢀHCl, EtOH, water,
reflux; (c) PPA, 125 °C; (d) R3X, Cs2CO3, DMF; (e) 10% Pd/C, N2H4ꢀH2O, EtOH, 60 °C.
Scheme 1. Target synthesis. Reagents and conditions: (a) R1R2NH, THF; (b) 2,4,5-
trichloropyrimidine, DIPEA, NMP, 100 °C; (c) DL-10-camphorsulfonic acid, IPA,
at 120 °C.
lW
In addition to optimizing for c-Met inhibition, medicinal chem-
istry efforts were directed at enhancing selectivity against the
insulin receptor kinase (IR)7 in particular, and against a broad pa-
nel of kinases in general. Kinase selectivity was determined using
Ambit Bioscience KINOMEscan™ technology and is expressed as
an S(90) value, which indicates the fraction of kinases inhibited
>90% when screened at 1 l
M across a panel of 256 kinases.8
The benzamide SAR is summarized in Table 1. Increasing size of
the secondary amide group (13 vs 16) led to reduced c-Met inhib-
itory activity. In this series, analog 14 was the most potent cellular
c-Met inhibitor and demonstrated fourfold selectivity for c-Met
over IR. Nonetheless, this analog demonstrated >90% inhibition of
151 out of 256 kinases when screened at 1 lM. Interestingly, the
propargyl benzamide analog 17 was also quite active while the
corresponding N-Me tertiary amide 18 was >20-fold less active.
Optimization thus focused on analogs of methylbenzamide 14.
Kinase selectivity was dramatically improved upon incorpora-
tion of a C3 substituent on the benzamide ring (e.g., a halogen or
methyl group, Table 2). For example, the S(90) value fell from
0.57 for analog 19 (X = H) to 0.02 for analog 21 (X = Cl). Although
analog 21 had improved selectivity, it had an unacceptably high
GTL-16 cell IC50. Analog 20 (X = F) represented a better compro-
mise; although the IR/c-Met IC50 ratio remained at 4, the S(90) va-
lue fell to 0.31 with no significant impact on c-Met potency or cell
translation. The C4-substituent was fixed as 2-amino-3-fluoro-N-
methylbenzamide, and medicinal chemistry focused on optimizing
the C2-benzazepin-2-one.
Scheme 2. Synthesis of 7-amino-1,3,4,5-tetrahydro-benzo[b]azepin-2-one (4).
Reagents and conditions: (a) NaOAc, NH2OHꢀHCl, EtOH, water, reflux; (b) PPA,
125 °C; (c) H2SO4, HNO3; (d) R3X, Cs2CO3, DMF; (e) 10% Pd/C, N2H4ꢀH2O, EtOH, 60 °C.
A similar synthesis was carried out to make the isomeric 8-ami-
no-1,3,4,5-tetrahydro-benzo[b]azepin-2-ones 5, and is shown in
Scheme 3. Nitration of tetralone 6 afforded 10. A Beckmann rear-
rangement of the corresponding oxime 11 produced the benzaz-
epinone 12a. Both 12a and 12b6 were either reduced or alkylated
and then reduced to give anilines 5.5

166
L. R. Weinberg et al. / Bioorg. Med. Chem. Lett. 21 (2011) 164–167
Table 1
c-Met SAR and kinase selectivity of benzamide analogs 13–18
a
Compd
R1
R1
IC50 (nM)
c-Met enzyme
c-Met cellb
IR enzyme
IR/c-Met enzyme
S(90)c
13
14
15
16
17
18
H
Me
n-Pr
n-Bu
CH2CCH
CH2CCH
H
H
H
H
H
Me
7
6
73
161
17
484
85
10
4
23
11
34
8
0.6
4
0.2
0.2
0.5
NTd
0.69
0.59
NTd
NTd
0.42
0.34
202
NTd
38
NTd
NTd
a
b
c
Average of at least two separate determinations; see Supplementary data for assay conditions.
GTL-16 cells.
Fraction of 256 kinases inhibited >90% when screened at 1
Not tested.
l
M.8
d
Table 2
c-Met SAR and kinase selectivity of benzamide analogs 19–23
R3
IC50 (nM)
a
Compd
X
c-Met enzyme
c-Met cellb
IR enzyme
IR/c-Met enzyme
S(90)c
19
20
21
22
23
H
F
Cl
Me
F
H
H
H
H
Et
54
45
159
203
56
80
102
1652
NTd
64
30
200
0.6
4
>40
NTd
6
0.57
0.31
0.02
0.04
0.23
>6500
NTd
334
a
b
c
Average of at least two separate determinations; see Supplementary data for assay conditions.
GTL-16 cells.
Kinase selectivity was determined using the Ambit Bioscience KINOMEscan™ technology.
Not tested.
d
Incorporation of an ethyl group on the 7-aminobenzazepinone
Analog 24 demonstrated modest IV and oral exposure in rat
(1 mg/kg IV, 5 mg/kg PO: IV t1/2 = 0.7 h; CL = 15 mL/min/kg; IV
AUC0–1 = 1261 ng h/mL; PO AUC0–1 = 592 ng h/mL; %F = 8%).
Analog 26, with its putatively metabolic benzylic sites protected
with methyl groups demonstrated lower oral exposure (1 mg/kg
nitrogen 23 maintained c-Met cell potency (cell IC50 = 64 nM)
and improved kinase selectivity (S(90) = 0.23, Table 2). However,
the IR IC50 was modestly affected and the IR/c-Met IC50 ratio re-
mained <10.
Initial results indicated that the IR/c-Met ratio was improved in
the 8-aminobenzazepinone series (Table 3). For example, benzaz-
epinone 25, R3 = methoxyethyl, maintained cellular c-Met inhibi-
tion and overall kinase selectivity but had increased separation
from IR activity (IR/c-Met IC50 ratio = 115). This SAR was more fully
explored in the 8-amino-5,5-dimethylbenzazepin-2-one series (Ta-
ble 4); c-Met inhibition fell while kinase selectivity (i.e., S(90) val-
IV, 5 mg/kg PO: IV t1/2 = 0.3 h; CL = 16 mL/min/kg; IV AUC0–1 =
1057 ng h/mL; PO AUC0–1 = 46 ng h/mL; %F <1%), and analog 27
had even lower IV and oral coverage. Current efforts are directed
at improving the PK properties of these analogs.
In summary, a series of 2,4-diaminopyrimidine analogs bearing
a C4-N-methylbenzamide and a C2-benzazepin-2-one was pre-
pared and representative compounds were shown to be potent
inhibitors of c-Met kinase. Kinase selectivity could be increased
without compromising c-Met cellular activity by incorporating a
fluorine atom at the C3 position of the pendant aminobenzamide.
Further improvement in kinase selectivity in general, and over IR
kinase in particular, could be realized by substitution of the ben-
zazepinone nitrogen. Thus, the S(90) values dropped from 0.57
ues) improved with increasing
a-branching of the lactam
substituent (R3). In this series, analog 27 (R3 = Et) possessed the
best balance of c-Met cellular potency (cell IC50 = 44 nM), selectiv-
ity against IR (IR/c-Met IC50 ratio = 73), and kinase selectivity
[S(90) = 0.17] see Supplementary data for a list of kinases inhibited
by this compound greater than 90% at1 lM).

L. R. Weinberg et al. / Bioorg. Med. Chem. Lett. 21 (2011) 164–167
167
Table 3
c-Met SAR and kinase selectivity of 8-aminobenzazepinone analogs 24–25
R3
IC50 (nM)
a
Compd
c-Met enzyme
c-Met cellb
IR enzyme
IR/c-Met enzyme
S(90)c
24
25
H
30
10
99
61
369
1150
12
115
0.24
0.25
(CH2)2OMe
a
b
c
Average of at least two separate determinations; see Supplementary data for assay conditions.
GTL-16 cells.
Kinase selectivity was determined using the Ambit Bioscience KINOMEscan™ technology.
Table 4
c-Met SAR and kinase selectivity of 8-amino-5,5-dimethylbenzazepinone analogs 26–30
R3
IC50 (nM)
a
Compd
c-Met enzyme
c-Met cellb
IR enzyme
IR/c-Met enzyme
S(90)c
26
27
28
29
30
H
Et
i-Pr
i-Bu
54
10
376
84
10
44
153
730
404
840
231
3
73
1
10
13
0.29
0.17
NTd
0.07
0.23
NTd
214
85
(CH2)2OMe
18
a
b
c
Average of at least two separate determinations; see Supplementary data for assay conditions.
GTL-16 cells.
Kinase selectivity was determined using the Ambit Bioscience KINOMEscan™ technology.
Not tested.
d
4. (a) Ott, G. R.; Tripathy, R.; Cheng, M.; McHugh, R.; Anzalone, A. V.; Underiner, T.
L.; Curry, M. A.; Quail, M. R.; Lu, L.; Wan, W.; Angeles, T. S.; Albom, M. S.;
Aimone, L. D.; Ator, M. A.; Ruggeri, B. A.; Dorsey, B. D. ACS Med. Chem. Lett. 2010.
doi:10.1021/ml100158s; (b) Zificsak, C. A.; Theroff, J. P.; Aimone, L. D.; Albom,
M. S.; Angeles, T. S.; Brown, R.; Galinis, D.; Grobelny, J. V.; Herbertz, T.; Husten,
J.; Kocsis, L. S.; LoSardo, C.; Miknyoczki, S. J.; Murthy, S.; Rolon-Steele, D.;
Underiner, T. L.; Worrell, C. S.; Zeigler, K.; Dorsey, B. D. Bioorg. Med. Chem. Lett.,
submitted for publication.
for our initial lead compound 19 to 0.17 for substituted analog 27
and the IR/c-Met IC50 ratio increased from 0.6 to 73 without
impacting c-Met cellular IC50 values (80 nM vs 44 nM,
respectively).
Supplementary data
5. Ahmed, G.; Bohnstedt, A.; Breslin, H. J.; Burke, J.; Curry, M. A.; Diebold, J. L.;
Dorsey, B.; Dugan, B. J.; Feng, D.; Gingrich, D. E.; Guo, T.; Ho, K.; Learn, K. S.;
Lisko, J. G.; Liu, R.; Mesaros, E. F.; Milkiewicz, K.; Ott, G. R.; Parrish, J.; Theroff, J.
P.; Thieu, T. V.; Tripathy, R.; Underiner, T. L.; Wagner, J. C.; Weinberg, L.; Wells,
G. J.; You, M.; Zificsak, C. A. International Patent WO 2008051547A1, 2008.
6. Smith, P. A. S.; Berry, W. L. J. Org. Chem. 1961, 26, 27.
Supplementary data (biological assay conditions, the kinase
profile for compound 27, experimental procedures and spectral
characterization) associated with this article can be found, in the
online version, at doi:10.1016/j.bmcl.2010.11.045.
7. As a key regulator of glucose metabolism, selectivity for c-Met over IR was
preferred to be >10-fold in enzyme assays.
8. Fabian, M. A.; Biggs, W. H.; Treiber, D. K.; Atteridge, C. E.; Azimioara, M. D.;
Benedetti, M. G.; Carter, T. A.; Ciceri, P.; Edeen, P. T.; Floyd, M.; Ford, J. M.; Galvin,
M.; Gerlach, J. L.; Grotzfeld, R. M.; Herrgard, S.; Insko, D. E.; Insko, M. A.; Lai, A.
G.; Lelias, J.; Mehta, S. A.; Milanov, Z. V.; Velasco, A. M.; Wodicka, L. M.; Patel, H.
K.; Zarrinkar, P. P.; Lockhart, D. J. Nat. Biotechnol. 2005, 23, 329.
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