7-(Aryl/heteroaryl-2-ylethynyl)-4-phenylamino-3-quinolinecarbonitriles as new Src kinase inhibitors: Addition of water solubilizing groups

Article abstract of DOI:10.1016/j.bmcl.2006.05.015

New 4-phenylamino-3-quinolinecarbonitriles with a 7-ethynyl group substituted by a pyridine, phenyl or thiophene ring containing basic water solubilizing groups were prepared and evaluated as Src kinase inhibitors. Of these new analogs, potent activity wa

Full text of DOI:10.1016/j.bmcl.2006.05.015

Bioorganic & Medicinal Chemistry Letters 16 (2006) 3993–3997
7-(Aryl/heteroaryl-2-ylethynyl)-4-phenylamino-3-
quinolinecarbonitriles as new Src kinase inhibitors:
Addition of water solubilizing groups
Biqi Wu,a,* Ana Carolina Barrios Sosa,a,1 Diane H. Boschelli,a Frank Boschelli,b
Erick E. Honores,a Jennifer M. Golas,b Dennis W. Powella and Yanong D. Wanga
aDepartment of Chemical and Screening Sciences, Wyeth Research, 401 N. Middletown Road, Pearl River, NY 10965, USA
bDepartment of Oncology, Wyeth Research, 401 N. Middletown Road, Pearl River, NY 10965, USA
Received 29 March 2006; revised 3 May 2006; accepted 4 May 2006
Available online 2 June 2006
Abstract—New 4-phenylamino-3-quinolinecarbonitriles with a 7-ethynyl group substituted by a pyridine, phenyl or thiophene ring
containing basic water solubilizing groups were prepared and evaluated as Src kinase inhibitors. Of these new analogs, potent activ-
ity was observed with compounds having a (2,4-dichloro-5-methoxyphenyl)amino group at C-4, a methoxy or ethoxy group at C-6,
and a pyridyl group bearing a dimethylamine or N-methylpiperazine on the ethynyl group at C-7.
Ó 2006 Elsevier Ltd. All rights reserved.
Src, a non-receptor tyrosine kinase, has a central role in
signaling pathways controlling cell proliferation and
migration.1 Over-expression or over-activation of Src
has been implicated in several diseases including cancer,
osteoporosis, stroke, and myocardial infarction.2a–e As a
result, Src has been recognized as a significant therapeu-
tic target and various classes of small molecule Src
inhibitors have been synthesized.3a–f
group, as exemplified by 1, retained activity against
Src.5a,b Based on these findings, new 4-phenylamino-7-
ethynyl-3-quinolinecarbonitriles containing basic water
solubilizing groups were designed and synthesized.
The synthesis of 7a–e and 9 is shown in Scheme 1.
Treatment of the allylic bromo group of 26a,6b,6c with di-
methylamine or N-methylpiperazine led to the amino-
methyl-substituted pyridines 3a–f. Reaction of 3a–e
with trimethylsilylacetylene followed by desilylation pro-
vided 4a–e. Intermediates 3b–c were also prepared via
reductive amination of 2-bromo formylpyridines 5. Sono-
gashira coupling of the 3-quinolinecarbonitriles 6a–c7a,7b
with 4a–e resulted in the analogs 7a–e. The 2,3-isomer of
7a, compound 9, was prepared by an alternative route.
Introduction of trimethylsilylacetylene onto C-7 of 6b7a
yielded 8 and subsequent coupling of 8 with 3f under
Sonogashira conditions with microwave heating gave 9.
Cl
Cl
O
Cl
Cl
HN
HN
O
O
O
CN
O
CN
N
N
N
N
SKI-606
1
N
In earlier work, we identified 7-alkoxy-4-phenylamino-
3-quinolinecarbonitriles as potent Src inhibitors, with
the optimal compound being SKI-606.4a–d It was recent-
ly shown that analogs where the 7-alkoxy group of
SKI-606 was replaced by a 7-ethynyl heteroaryl/aryl
As shown in Table 1, positional variation of the dime-
thylaminomethyl group on the pyridine ring had a large
effect on Src inhibition. Moving the dimethylaminom-
ethyl group from C-6 (7c) to C-5 (7b) to C-4 (7a) to
C-3 (9) of the pyridine decreased Src-inhibitory activity.
Of these analogs, the 2,6-pyridine isomer 7c was the
most potent inhibitor, having an IC50 of 4.5 nM in the
Src enzyme assay and an IC50 of 120 nM in a Src-depen-
dent cell proliferation assay. The 2,3-pyridine isomer 9
Keywords: Src; 3-Quinolinecarbonitrile.
*
Corresponding author. Tel.: +1 845 602 5131; fax: +1 845 602
5561; e-mail: wub@wyeth.com
1
Current address: Roche Carolina Inc., Pharmaceutical Process
Development, 6173 East Old Marion Highway, Florence, SC
29506-9330, USA.
0960-894X/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2006.05.015

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B. Wu et al. / Bioorg. Med. Chem. Lett. 16 (2006) 3993–3997
4
group had similar potency to the dimethylamino-substi-
5
6
3
2
a
b
tuted analog 7c. In general, the analogs 7c and 7e with a
C-6 group were more active than the analogs 7b and 7d
with a C-5 group in the Src cell assay.
Br
R
R
Br
N
N
N
Br
2
3a: R = 4-NMe2
3b: R = 5-NMe2
3c: R = 6-NMe2
3d: R = 5-N-Me-piperazine
3e: R = 6-N-Me-piperazine
3f: R = 3-NMe2
4a: R = 4-NMe2
c
4b: R = 5-NMe2
4c: R = 6-NMe2
4d: R = 5-N-Me-piperazine
4e: R = 6-N-Me-piperazine
An isomer of 7c where there is a 3,5-substituted pyri-
dine on the ethynyl group at C-7 was prepared by
the route shown in Scheme 2. Treatment of 108 with
trimethylsilylacetylene gave 11. Coupling of 11 with
6c7b resulted in the formation of 12. Mesylation of
12 with MsCl followed by addition of dimethylamine
provided 13. The 3,5-pyridine isomer 13 had a similar
activity to the 2,6-pyridine isomer 7c, with 13 having
IC50s of 3.6 and 150 nM in the enzyme and cell assays,
respectively.
OHC
N
Br
5
Cl
Cl
O
Cl
Cl
O
HN
HN
N
d
O
CN
O
CN
N
X
6a: X = Br
6b: X = I
N
R
In order to investigate the effect of lengthening the
chain, analogs with an aminoethyl group at C-6 of
the 2-pyridine were prepared (Scheme 3). Reduction
of 149 with DIBAL-H yielded 15. Sonogashira cou-
pling of 15 with 8 under microwave heating gave 16.
Treatment of 16 with MsCl followed by addition of
dimethylamine or N-methylpiperazine provided 17a
and 17b. Compared to 7c, these analogs had similar
Src enzyme activity and showed slightly improved
Src cell activity.
6c: X = OTf
7a: R = 4-NMe2
7b: R = 5-NMe2
7c: R = 6-NMe2
7d: R = 5-N-Me-piperazine
7e: R = 6-N-Me-piperazine
e
Cl
Cl
O
HN
O
CN
Cl
Cl
O
N
HN
TMS
8
f
O
CN
N
N
We next looked at the effect of replacing the pyridine
with a thiophene or phenyl group on Src-inhibitory
activity. The preparation of these analogs is depicted
in Scheme 4. Reductive amination of 5-bromo-2-thio-
phene-carboxaldehyde 18 with dimethylamine gave 19.
Treatment of 19 with trimethylsilylacetylene followed
by desilylation provided 20. Coupling of 20 with 6b
led to the thiophene analog 21. The phenyl analogs
24a and 24b were prepared by using the same conditions
as those used to prepare 9. Replacement of the allylic
bromo group of 22a or 22b with dimethylamine yielded
23a or 23b. Subsequent reaction of 23a or 23b with 8
provided the two isomers 24a or 24b, respectively. The
2-thiophene analog 21 was about three times less active
than 7c in both the enzyme and cell assays. The 4-phenyl
isomer 24b was more potent than the 3-phenyl isomer
24a, having an IC50 of 5.3 nM in the enzyme assay
and an IC50 of 190 nM in the cell assay.
9
N
Scheme 1. Reagents and conditions: (a) Me2NH or N-Me-piperazine,
}
Hunig’s base, MeCN; (b) (1) TMS–acetylene, Pd(PPh3)2Cl2, CuI,
diisopropylamine, THF; (2) 1 N aq K2CO3, MeOH; (c) Me2NH,
Na(OAc)3BH, AcOH, CH2Cl2; (d) 4a–e, Pd(PPh3)4, CuI, Et3N,
dioxane; (e) TMS–acetylene, Pd(PPh3)2Cl2, CuI, diisopropylamine,
THF; (f) 3f, Pd(PPh3)2Cl2, CuI, PPh3, K2CO3, DMF, CH3OH,
microwave.
was a much less active inhibitor, having an IC50 of only
2700 nM in the Src enzyme assay. It was observed that
replacement of the dimethylamino group of 7b with
N-methylpiperazine to provide 7d led to a 2-fold de-
crease in activity in the Src enzyme and cell assays.
However, 7e bearing a 6-methyl-N-methylpiperazine
TMS
Br
HO
a
HO
N
N
10
11
b
Cl
Cl
O
Cl
Cl
O
HN
HN
O
CN
O
CN
OH
N
N
N
12
13
N
N
Scheme 2. Reagents and conditions: (a) TMS–acetylene, Pd(PPh3)2Cl2, CuI, diisopropylamine, THF; (b) 6c, Pd(PPh3)2Cl2, CuI, PPh3, K2CO3, THF,
CH3OH; (c) (1) MsCl, TEA, THF, DMF; (2) Me2NH.

B. Wu et al. / Bioorg. Med. Chem. Lett. 16 (2006) 3993–3997
Table 1. Src enzyme and cell-inhibitory activity of 7-ethynyl-3-quinolinecarbonitriles
3995
RAr
HN
N
R
CN
R'
Compound12
RAr
R0
R
Src enzyme
IC50 (nM)4e,13
Src cell
IC50 (nM)4a,13
SKI-606
1
7a
3.84e
125b
18
1004b
2705b
580
240
120
390
120
NT
150
87
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
2,4-DiCl-5-OMe
3,4,5-Tri-OMe
3-Pyridine
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OMe
OEt
2-Pyridyl-4-CH2NMe2
2-Pyridyl-5-CH2NMe2
2-Pyridyl-6-CH2NMe2
7b
7c
4.9
4.5
9.0
4.2
2700
3.6
5.3
4.3
15
7d
7e
2-Pyridyl-5-CH2-N-Me-piperazine
2-Pyridyl-6-CH2-N-Me-piperazine
2-Pyridyl-3-CH2NMe2
9
13
3-Pyridyl-5-CH2NMe2
17a
17b
21
2-Pyridyl-6-(CH2)2NMe2
2-Pyridyl-6-(CH2)2N-Me-piperazine
2-Thienyl-5-CH2NMe2
Phenyl-3-CH2NMe2
81
390
230
190
86
24a
24b
26a
26b
28a
28b
9.9
5.3
3.6
22
Phenyl-4-CH2NMe2
2-Pyridyl-6-CH2NMe2
2-Pyridyl-6-CH2NMe2
2-Pyridyl-6-CH2NMe2
2-Pyridyl-6-CH2NMe2
H
470
350
2200
OMe
H
29
120
3,4,5-Tri-OMe
a
MeO2C
N
6-methoxy analog 7c and its 6-hydrogen analog 26b.
Compound 7c was about 5-fold more potent than 26b
in the enzyme assay and 4-fold more potent in the cell
assay. We had previously reported11,5b that a 3,4,5-tri-
methoxyanilino group at C-4 of 3-quinolinecarbonitriles
also provided a series of Src inhibitors. However, a
decrease in Src inhibition was observed in both the Src
enzyme and cell assays when the 2,4-dichloro-5-meth-
oxyanilino group at C-4 of 7c was replaced with a
3,4,5-trimethoxyanilino group. 28a, the 3,4,5-trimeth-
oxyanilino analog of 7c, had an IC50 of 29 nM in the
enzyme assay and an IC50 of 350 nM in the cell assay.
As expected, 28b, the 6-hydrogen analog of 28a, showed
greatly reduced Src-inhibitory activity.
Br
HO
Br
N
14
15
b
Cl
Cl
O
Cl
Cl
O
HN
HN
O
CN
O
CN
c
N
N
16
N
N
17a: R = Me2N
17b: R = N-Me-piperazine
OH
R
Scheme 3. Reagents and conditions: (a) DIBAL-H, THF; (b) 8,
Pd(PPh3)2Cl2, CuI, PPh3, K2CO3, DMF, CH3OH, microwave; (c) (1)
MsCl, TEA, THF, DMF; (2) Me2NH or N-Me-piperazine.
Several of these 7-ethynyl analogs had comparable
activity to SKI-606 and 7c was chosen for a pharmaco-
kinetic study. Twenty-four hours after administration of
a single oral 50 mg/kg dose to nude mice, the plasma lev-
els of 7c were about a third those of SKI-606 under the
same conditions. Studies with nude mouse liver micro-
somes showed that the metabolic stability of 7c was low-
er than that of SKI-606. In an in vivo HT29 xenograft
study, 7c had only moderate activity, possibly as a result
of its lower plasma level and shorter half-life compared
to these same parameters for SKI-606. We are contin-
uing to investigate other 4-[(2,4-dichloro-5-methoxyphe-
nyl)amino]-3-quinolinecarbonitriles with various groups
at C-7.
Finally, the effect of variation of the C-6 group and the
C-4 headpiece on Src inhibition was investigated.
Scheme 5 shows the preparation of 7-[2-(2-pyridyl)-ethy-
nyl]-3-quinolinecarbonitriles with different groups at C-
6 and C-4 of the core structure. Coupling of 25a7a,
25b10, 27a5b and 27b5b with 4d afforded 26a, 26b, 28a
and 28b, respectively. Compound 26a with an ethoxy
substituent at C-6 had a moderate increase in activity
in both the Src enzyme and cell assays compared to
7c. A large difference in potency was seen between the

3996
B. Wu et al. / Bioorg. Med. Chem. Lett. 16 (2006) 3993–3997
b
a
N
N
OHC
Br
Br
S
S
S
20
19
18
Cl
Cl
HN
O
c
O
CN
N
21
S
N
Cl
Cl
O
HN
e
d
O
CN
N
Br
Br
Br
N
3
22a: 3-isomer
22b: 4-isomer
23a: 3-isomer
23b: 4-isomer
24a; 3-isomer
24b: 4-isomer
4
N
Scheme 4. Reagents and conditions: (a) Me2NH, Na(OAc)3BH, AcOH, CH2Cl2; (b) (1) TMS–acetylene, Pd(PPh3)2Cl2, CuI, diisopropylamine, THF;
}
(2) 1 N aq K2CO3, MeOH; (c) 6b, Pd(PPh3)4, CuI, Et3N, dioxane; (d) Me2NH, Hunig’s base, MeCN; (e) 8, Pd(PPh3)2Cl2, CuI, PPh3, K2CO3, MeOH,
DMF, microwave.
2. (a) Yeatman, T. J. Nat. Rev. Cancer 2004, 4, 470; (b)
Cl
Cl
O
Cl
Cl
O
Frame, M. C. Biochim. Biophys. Acta 2002, 1602, 114; (c)
Susva, M.; Missbach, M.; Green, J. Trends Pharmacol.
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Cravens, A.; McSharry, H.; Iwakura, A.; Yoon, Y.-S.;
Himes, N.; Burstein, D.; Doukas, J.; Soll, R.; Losordo, D.;
Cheresh, D. J. Clin. Invest. 2004, 113, 885.
HN
HN
a for 26a
b for 26b
R
X
CN
R
CN
N
N
25a: X = I, R = OEt
25b: X = Br, R = H
26a: R = OEt
26b: R = H
N
N
3. (a) Missbach, M.; Jeschke, M.; Feyen, J.; Muller, K.;
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N.; Dutia, M.; Powell, D. W.; Wissner, A.; Arndt, K.;
Weber, J. M.; Boschelli, F. J. Med. Chem. 2001, 44, 822;
(b) Boschelli, D. H.; Ye, F.; Wang, Y. D.; Dutia, M.;
Johnson, S. L.; Wu, B.; Miller, K.; Powell, D. W.; Yaczko,
D.; Young, M.; Tischler, M.; Arndt, K.; Discafani, C.;
Etienne, C.; Gibbons, J.; Grod, J.; Lucas, J.; Weber, J. M.;
Boschelli, F. J. Med. Chem. 2001, 44, 3965; (c) Golas, J.
M.; Arndt, K.; Etienne, C.; Lucas, J.; Nardin, D.;
Gibbons, J.; Frost, P.; Ye, F.; Boschelli, D. H.; Boschelli,
F. Cancer Res. 2003, 63, 375; (d) Golas, J. M.; Lucas, J.;
O
O
O
O
O
a
HN
N
HN
O
R
CN
R
X
CN
N
27a: X = OTf, R = OMe
27b: X = Br, R = H
28a: R = OMe
28b: R = H
N
N
Scheme 5. Reagents and conditions: (a) for 26a, 28a, and 28b: 4d,
Pd(PPh3)4, CuI, Et3N, dioxane; (b) for 26b: 4d, Pd(PPh3)2Cl2, CuI,
PPh3, K2CO3, DMF, CH3OH, microwave.
Acknowledgments
We thank the members of the Wyeth Chemical Technol-
ogy Department for their services, Judy Lucas for the
in vivo studies, and the Drug Safety and Metabolism
Department for the metabolic stability and plasma level
determinations. We also thank Drs. Janis Upeslacis and
Tarek Mansour for advice and support.
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B. Wu et al. / Bioorg. Med. Chem. Lett. 16 (2006) 3993–3997
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CHN combustion analyses.
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13. Assay: IC50 values represent means of at least two separate
determinations.