Synthesis and PKCθ inhibitory activity of a series of 5-vinyl phenyl sulfonamide-3-pyridinecarbonitriles

Article abstract of DOI:10.1016/j.bmcl.2009.10.031

A series of 5-vinyl phenyl sulfonamide-3-pyridinecarbonitriles were prepared and evaluated as PKCθ inhibitors. Optimization resulted in the identification of compound 15 with an IC₅₀ value 0.44 nM for the inhibition of PKCθ with 150-fold select

Full text of DOI:10.1016/j.bmcl.2009.10.031

Bioorganic & Medicinal Chemistry Letters 19 (2009) 6575–6577
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Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis and PKCh inhibitory activity of a series of 5-vinyl phenyl
sulfonamide-3-pyridinecarbonitriles
a
b
b
b
a
Jaechul Shim a, , Clark Eid , Julie Lee , Erica Liu , Divya Chaudhary , Diane H. Boschelli
*
a Chemical Sciences, Wyeth Research, 401 N. Middletown Road, Pearl River, NY 10965, USA
b Inflammation, Wyeth Research, 200 Cambridge Park Drive, Cambridge, MA 02140, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of 5-vinyl phenyl sulfonamide-3-pyridinecarbonitriles were prepared and evaluated as PKCh
inhibitors. Optimization resulted in the identification of compound 15 with an IC50 value 0.44 nM for
the inhibition of PKCh with 150-fold selectivity over PKCd.
Received 15 September 2009
Revised 5 October 2009
Accepted 7 October 2009
Available online 13 October 2009
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Kinase
PKCh
3-Pyridinecarbonitrile
The protein kinase C (PKC) family of serine–threonine kinases
share sequence homology but vary in their activation require-
earlier reported that the 5-phenyl-3-pyridinecarbonitrile 1a had
an IC50 value of 7.4 nM for the inhibition of PKCh.12
ments, expression and regulation.1 Conventional PKCs (
a
, b, and
) require calcium and diacylglycerol as secondary messengers,
the novel PKCs (d, , and h) do not require calcium, and the atyp-
Insertion of a vinyl group at C-5 to provide 1b increased the PKCh
inhibitory activity (IC50 = 3.6 nM) and also increased the selectivity
for PKCh over PKCd from sevenfold to 11-fold (Table 1).15 This in-
creased potency and selectivity of 1b compared to 1a prompted a
study of replacing the ethoxy tether between the phenyl ring and
the amine with additional groups. This Letter focuses on sulfon-
amide replacements for the ethoxy moiety that would have the po-
tential of forming multiple hydrogen bonding interactions.16
The desired sulfonamides were prepared by Heck coupling of the
corresponding bromobenzenesulfonamides with the 5-vinyl-3-
pyridinecarbonitrile 2a15 (Scheme 1). The bromobenzenesulfona-
mides were prepared from the corresponding sulfonyl chlorides
and amines. The p-N-Methylpiperazinesulfonamide analog 3 inhib-
ited PKCh with an IC50 of 23 nM with 6.1-fold selectivity over PKCd
Table 1. The pyrrolidine and piperidine analogs 4 and 5 had
c
e, g
ical isoforms (f and k) require neither calcium nor diacylglycerol.2
PKCh was first characterized in 1993 and is predominantly ex-
pressed in T cells.3 Studies using PKCh knock-out (KO) mice have
established the role of this kinase in diseases such as multiple scle-
rosis, arthritis, asthma, inflammatory bowel disease and organ
transplantation.4 PKCh displays particularly high homology to
PKCd. PKCd deficiency in mice led to a hyperproliferation of B cells
and overproduction of inflammatory cytokines.5 Therefore we used
PKCd as the primary counter assay in our inflammation project.
Several chemical series have been shown to be ATP-competitive
inhibitors of PKCh including 2,4-diamino pyrimidines,6 thieno[2,3-
b]pyridinecarbonitriles7–9 and 3-pyridinecarbonitriles.10–15 We
NH
NH
O
O
N
HN
N
N
HN
N
N
CN
N
CN
1a
1b
* Corresponding author. Tel.: +1 845 602 1681; fax: +1 845 602 5561.
E-mail address: shimj@wyeth.com (J. Shim).
0960-894X/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2009.10.031

6576
J. Shim et al. / Bioorg. Med. Chem. Lett. 19 (2009) 6575–6577
Table 1
Table 2
PKCh and PKCd inhibitory activity of 5-vinyl phenyl sulfonamide-3-pyridinecarbo-
PKCh and PKCd inhibitory activity of 5-vinyl phenyl sulfonamide-6-methyl-3-pyridine-
nitriles
carbonitriles
NH
NH
O
O
R'
R'
HN
HN
N S
N
S
CN
CN
R''
R''
O
O
N
Me
N
Compd NR0R00
PKCh IC50a, nM PKCd IC50a, nM d/h
Compd
NR0R00
PKCh IC50a, nM
PKCd IC50a, nM
d/h
1a
1b
3
4
5
6
7
8
9
10
11
12
13
14
7.4
3.6
23
6.0
12
51
41
140
450
20,000
114
1,300
3,300
51,000
9,400
NTb
120
390
18
6.9
11
6.1
75
1700
21
120
380
150
23
15
16
17
18
19
20
m-N-Methylpiperazine
m-Pyrrolidine
m-Piperidine
p-N-Methylpiperazine
p-Pyrrolidine
p-Piperidine
0.44
2.4
4.8
9.3
21
65
850
2,000
4,400
7,100
21,000
150
350
420
470
340
310
p-N-Methylpiperazine
p-Pyrrolidine
p-Piperidine
p-NH2
p-NMe2
p-NEt2
p-N(n-Pr)2
p-N(iso-Pr)2
p-NH(sec-Bu)
m-Pyrrolidine
m-Piperidine
5.4
11
68
a
Values are the mean of at least two determinations.
8.7
350
410
121
6.0
3.0
PKCh with an IC50 value of 0.44 nM with 150-fold selectivity over
PKCd. Unfortunately, the microsomal half lives were not improved.
Compound 15 showed half lives of less than 30 min in mouse, rat,
and human microsomal stability assays.
—
20
130
37
m-N-Methylpiperazine 0.49
Another variation on the existing template was carried out by
inserting a methylene unit between the sulfonamide and aryl moi-
eties. Bromobenzyl bromides were refluxed with sodium sulfite
and a catalytic amount of N,N,N,N-tetrabutylammonium iodide.
Phosphorus pentachloride in phosphorus oxychloride was used
to form the sulfonyl chlorides which were converted to the corre-
sponding sulfonamides.17 The sulfonamides were coupled with 2a
and 2b via a Heck reaction (see Scheme 2).
Assay protocols are described in Ref. 10.
a
Values are the mean of at least two determinations.
NT = not tested.
b
O
S
O
S
R'
a
Cl
N
R''
Br
NH
O
Br
O
The effect of inserting a methylene between the phenyl and
4-methylpiperaziny-1-ylsulfonyl groups is shown in Table 3. In
general, the activity against PKCh and the selectivity against PKCd
NH
HN
CN
2a (R = H)
2b (R = Me)
O
R'
HN
N
S
O
CN
O
b
a
R''
R
N
O
R'
S
Br
S
O
N
NaO
b
O
Br
Br
Br
R
N
R''
Scheme 1. Reagents and conditions: (a) R0R00NH, CH2Cl2, 23 °C (b) P(o-tol)3,
Pd(OAc)2, NEt3, DMF, 100 °C.
NH
O
c
HN
N
R'
S
O
CN
N
improved PKCh activity and selectivity over PKCd, with 5 exhibiting
an exceptional 1700-fold selectivity. In the case of acyclic
sulfonamides (compounds 6–11), the activity fell off sharply with
the increasing size of the amine. The best profile was seen
with the diethylamino analog 8 which had an IC50 value of 8.7 nM
for the inhibition of PKCh with 380-fold selectivity over PKCd. It
was notable that the acidic unsubstituted sulfonamide 6 showed
similar potency to 3 which contains a basic amine as polar group.
When the substitution pattern was changed from para to meta
with cyclic amines, a general improvement in PKCh activity re-
sulted with a concomitant increase in PKCd activity. The m-N-
methylpiperazine analog, 14, was particularly active with an IC50
value of 0.49 nM against PKCh and 37-fold selectivity over PKCd.
Compounds in Table 1 showed half lives of less than 10 min in
rat liver microsome stability assays. Metabolism studies of 14
identified a major site of oxidation to be the 6-position of the
3-pyridinecarbonitrile core.
R''
(R = H or Me)
R
Scheme 2. Reagents and conditions: (a) Na2SO3, (n-Bu)4NI, water, reflux (b) PCl5,
POCl3, 120 °C; R0R00NH, CH2Cl2 (c) 2a or 2b, P(o-tol)3, Pd(OAc)2, NEt3, DMF, 100 °C.
Table 3
PKCh and PKCd inhibitory activity of 5-vinyl benzyl sulfonamide-3-pyridinecar-
bonitriles
NH
O
HN
S
O
CN
N
N
R
N
Compd
R
m/p-
PKCh IC50a, nM
PKCd IC50a, nM
d/h
In order to block the site of metabolism, a 6-methyl moiety was
introduced by employing compound 2b18 (R = Me) in the Heck
coupling with the bromobenzenesulfonamides. The SAR of the
6-methyl analogs (Table 2) generally corresponded to that of the
unsubstituted derivatives. In all cases, except 20, the selectivity
of PKCh over PKCd was greatly enhanced. Compound 15 inhibited
21
22
23
24
H
H
p
m
p
7.9
6.2
4.3
4.4
320
94
110
97
41
15
26
22
Me
Me
m
a
Values are the mean of at least two determinations.

J. Shim et al. / Bioorg. Med. Chem. Lett. 19 (2009) 6575–6577
6577
Table 4
Acknowledgments
Kinase selectivity of 14 and 15
a
a
Kinase
IC50 (nM) of 14
IC50 (nM) of 15
We thank the Wyeth Chemical Technologies department for
compound characterization and the microsome stability results,
Drs. James Atherton and Jack Wang for metabolite ID of 14, Drs.
Natasja Brooijmans and Jack Bikker for molecular modeling,
Screening Sciences for kinase profiling and Dr. Tarek Mansour for
his support.
PKCe
1.6
100
36
490
PKCg
PKCb
PKCf
PKA
HCK
LYN A
SRC
FYN
41,000
>100,000
130
>50,000
>100,000
1300
550
290
220
140
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
References and notes
GCK
1,300
2,400
VEGFR2
CDK1/cyclinB
CDK2/cyclinA
Aurora B
ROCK1
1. Spitaler, M.; Cantrell, D. A. Nat. Immunol. 2004, 5, 785.
2. Hug, H.; Sarre, T. F. Biochem. J. 1993, 291, 329.
>50,000
44,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
>50,000
3. Berg-Brown, N. N.; Gronski, M. A.; Jones, R. G.; Elford, A. R.; Deenick, E. K.;
Odermatt, B.; Littmann, D. R.; Ohashi, P. S. J. Exp. Med. 2004, 199, 743.
4. Baier, G.; Wagner, J. Curr. Opin. Cell Biol. 2009, 21, 262.
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6. Cywin, C. L.; Dahmann, G.; Prokopowicz, A. S.; Young, E. R. R.; Magolda, R. L.;
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Homon, C. A.; Farrell, T. M.; Grbic, H.; Hu, H.; Kaplita, P. V.; Liu, L. H.; Spero, D.
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CK1
c
1
MK2
P38
a
ERK2
CHK1
RSK1
PDGFR
a
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a
Values are the mean of at least two determinations.
were both diminished. Methylene insertion did not change the pat-
tern of low microsomal stability.
10. Cole, D. C.; Asselin, M.; Brennan, A.; Czerwinski, R.; Ellingboe, J. W.; Fitz, L.;
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Table 4 illustrates the kinase selectivity profile for the two most
active compounds 14 and 15. While compound 14 was found to ex-
hibit a high affinity for PKCe, another novel PKC, both were very
selective (more than 100-fold) over PKC
g
a novel PKC, PKCb a con-
ventional PKC and PKCf an atypical PKC. Enhanced selectivity
across the board was exhibited for the C-6 methyl analog 15.
In summary, a series of 3-pyridinecarbonitriles containing a C-5
vinyl phenyl sulfonamide group were found to be potent and selec-
tive inhibitors of PKCh. Small changes in either the amino group,
the position of the sulfonamide on the phenyl ring or the presence
of a methyl group at C-6 affected activity and selectivity. The
source of the selectivity observed with these analogs is unclear gi-
ven our current structural biology knowledge. There is very high
identity in the ATP binding sites of PKCh and PKCd. The amino acid
residues relatively close to the binding cleft that vary include the
Tyr460 of PKCh that corresponds to a Phe in PKCd and the Ile510
of PKCh that corresponds to a Val in PKCd, neither of which makes
an apparent direct contact with the inhibitors.
14. Prashad, A. S.; Wang, D.; Subrath, J.; Wu, B.; Lin, M.; Zhang, M.-Y.; Kagan, N.;
Lee, J.; Yang, X.; Brennan, A.; Chaudhary, D.; Xu, X.; Leung, J.; Wang, J.;
Boschelli, D. H. Bioorg. Med. Chem. Lett. 2009, 19, 5799.
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Wu, B.; Eid, C.; Lee, J.; Yang, X.; Brennan, A.; Chaudhary, D. Bioorg.
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