Synthesis and bioactivities of novel piperidylpyrimidine derivatives: Inhibitors of tumor necrosis factor-alpha production

Article abstract of DOI:10.1016/S0960-894X(00)00227-4

New piperidylpyrimidine derivatives, including quinazolines, were prepared, and their abilities to inhibit TNF-α production evaluated. Some compounds showed potent inhibitory activity in mouse macrophages stimulated with LPS. The synthesis and structure-activity relationships of these compounds are described. (C) 2000 Elsevier Science Ltd. All rights reserved.

Full text of DOI:10.1016/S0960-894X(00)00227-4

Bioorganic & Medicinal Chemistry Letters 10 (2000) 1317±1320
Synthesis and Bioactivities of Novel Piperidylpyrimidine
Derivatives: Inhibitors of Tumor Necrosis Factor-Alpha Production
Norio Fujiwara,* Hitoshi Fujita, Kiyotaka Iwai, Ayumu Kurimoto,
Shinobu Murata and Hajime Kawakami
Research Center, Sumitomo Pharmaceuticals Co., Ltd., 1-98, Kasugade Naka 3-chome, Konohana-ku, Osaka 554±0022, Japan
Received 18 February 2000; accepted 4 April 2000
AbstractÐNew piperidylpyrimidine derivatives, including quinazolines, were prepared, and their abilities to inhibit TNF-a pro-
duction evaluated. Some compounds showed potent inhibitory activity in mouse macrophages stimulated with LPS. The synthesis
and structure±activity relationships of these compounds are described. # 2000 Elsevier Science Ltd. All rights reserved.
Tumor necrosis factor-a (TNF-a) is a key pro-in¯amma-
tory cytokine that is produced mainly by activated
monocyte/macrophages in response to immunostimu-
lants. Increasing evidence indicates that TNF-a is a major
mediator of in¯ammatory and immune responses and that
it has pleiotropic biological e€ects.1 Elevated TNF-a
levels also have been implicated in the pathogenesis of
such diseases as septic shock,2,3 cachexia,4,5 rheumatoid
arthritis (RA),6,7 in¯ammatory bowel disease (IBD)8
and AIDS.9 11 Moreover, TNF-a is a strong inducer of
such other pro-in¯ammatory cytokines as IL-1, IL-6 and
IL-8.7 Agents which inhibit TNF-a production therefore
may have therapeutic potential for the direct or indirect
treatment of these diseases. In clinical trials, monoclonal
antibodies to TNF-a have been e€ective in the treatment
of RA and Crohn's disease.12 15 During screening for
compounds that inhibit TNF-a production, benzoyl-
substituted piperidylquinazolinone (3)16 was found to
have such activity. Using this as the lead compound, we
obtained some modi®ed compounds. We found that cer-
tain piperidylpyrimidines are potent inhibitors of TNF-a
production in LPS-stimulated mouse macrophages. The
synthesis and structure±activity relationships in this series
of compounds are described.
1
17 and subsequent selective ortho acylation18 with aniline
in the presence of boron trichloride and aluminum
trichloride gave 2-aminophenyl ketone 2. The compound
2 was cyclized with potassium cyanate and cyanamide,
yielding the respective 2-oxo (3) and 2-amino (4) quina-
zolines. Non-aqueous diazotization-replacement of 2-
aminoquinazoline 4 by the tert-butyl nitrite (TBN)-SbCl3
system19 gave 2-chloroquinazoline 5 which was converted
to 6 by hydrogenolysis. Hydrolysis of 4, followed by
alkylation or acylation in the usual manner gave a series of
substituted amino or amide compounds 8a±j.
2,4-diaminoquinazoline derivatives 11a±c were prepared
from 2,4-dichloroquinazoline 9 by stepwise reactions
with the requisite amines (Scheme 2).20,21
Pyrimidine derivatives modi®ed at the C(6)-position were
prepared as shown in Scheme 3. Condensation of the
requisite ketones with the acid chloride of 1222 followed
by cyclization with guanidine gave 14a and 14b. In the
case of 4-methoxyphenylacetone, a 1:1 mixture of the 1,3-
diketone isomers 13c and 13d was produced. Each of these
chromatographically separable isomers could be pro-
cessed to the desired pyrimidines, 14c and 14d, respec-
tively (Scheme 4). Hydrolysis of 14c, followed by acylation
with the requisite acid chloride and triethylamine or the
requisite acid and 1-(3-dimethylaminopropyl)-3-ethylcar-
bodiimide (WSC) gave the series of amide compounds
16a±x. The test compounds were puri®ed by standard
procedures like column chromatography and crystal-
lization. Structures were con®rmed with NMR and MS
spectroscopy.
Chemistry and Biology
The compounds in Tables 1±4 were synthesized as outlined
in Schemes 1±4. Quinazoline derivatives modi®ed at the
C(2)-position and piperidine nitrogen were prepared as
shown in Scheme 1. Benzoylation of 4-cyanopiperidine
Compounds were evaluated for their abilities to inhibit
TNF-a production in mouse macrophages stimulated
*Corresponding author. Fax: +81-6-6466-5483; e-mail: nfujiwar@
sumitomopharm.co.jp
0960-894X/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved.
PII: S0960-894X(00)00227-4

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N. Fujiwara et al. / Bioorg. Med. Chem. Lett. 10 (2000) 1317±1320
Table 1. SAR of 2-substitution
Table 3. SAR of benzo fusion
R4
R5
TNF-a inhibition IC50 (mM)
Compound
X
TNF-a inhibition IC50 (mM)
Compound
3
4
5
6
OH
NH2
Cl
20
14a
14b
14c
14d
H
H
H
CH3
Ph
4-CH3OPhCH2
CH3
9.0
5.1
1.4
9.7
1.4
1.4
1.4
H
4-CH3OPh
Table 2. SAR of piperidine substitution
Table 4. SAR of piperidine substitution
R6
TNF-a inhibition IC50 (mM)
Compound
R1
TNF-a inhibition IC50 (mM)
Compound
7
H
CH3
Bn
51
>100
16
>100
53
16a
16b
16c
16d
16e
16f
16g
16h
16i
CH3
CH3CH2
CH3(CH2)2
CH3(CH2)4
CH3(CH2)6
t-Bu
2-CH3OPh
3-CH3OPh
4-CH3OPh
2-NO2Ph
3-NO2Ph
4-NO2Ph
4-ClPh
6.1
4.9
7.2
1.5
1.9
5.6
3.6
1.2
0.5
1.7
0.8
0.7
0.6
0.9
0.9
1.0
0.6
0.7
2.1
1.7
2.4
1.2
1.8
2.1
8a
8b
8c
8d
8e
8f
8g
8h
8i
Ph(CH2)2
Cyclohexyl
Ac
3.6
3.0
2.5
2.0
6.3
4.5
CH3(CH2)3CO
Cyclohexanoyl
PhCH2CO
Ph(CH2)2CO
3,4-(OCH2O)PhCO
16j
16k
16l
8j
11a
11b
11c
>100
>100
>100
16m
16n
16o
16p
16q
16r
16s
16t
16u
16v
16w
16x
2,3-(CH3O)2Ph
3,4-(CH3O)2Ph
3,5-(CH3O)2Ph
3,4-(OCH2O)Ph
3,4-Cl2Ph
with LPS as described elsewhere.23 Test results are given
as the IC50 values (mM) of a single determination.
Pentoxifylline24 27 (Sigma Co.) was the positive control
used to give an IC50 of 23 mM.
PhCH2
4-CH3OPhCH2
4-ClPhCH2
3,4-(CH3O)2PhCH2
3,4-(OCH2O)PhCH2
3,4-Cl2PhCH2
Results and Discussion
C(4)-position of quinazoline had diminished potency.
The poor activities of these amino analogues suggest
that this region must be nonbasic in order to be a potent
TNF-a inhibitor.
Compounds in which the substitution at the C(2)-posi-
tion of the quinazoline ring varied are shown in Table 1.
There was a marked increase in activity in this series as
compared with 3, the initial lead compound. The struc-
tural form of 3, preferably the keto tautomeric form28,29
depicted in Scheme 1, suggests that the electron-rich
N(1)-nitrogen of quinazoline acts as a hydrogen-bond
acceptor and that this nitrogen is important for activity.
The results in Table 3 show the e€ect of substituted
pyrimidines that dissociated the benzo moiety of quina-
zoline. Modi®cation of the benzo moiety was tolerated,
and of the analogues prepared, benzyl analogue 14c had
a potency equal to its benzo derivative 4. Compound
14a (R4=H, R5=Me) showed decreased potency, indi-
cative of the importance of the lipophilic group for
good potency. The lipophilic-substituted analogue 14d
(R4=4-methoxyphenyl, R5=Me) in particular reduced
activity relative to 14b (R4=H, R5=Ph), indicative that
a bulkier group at the C(5)-position of pyrimidine may
distort the active conformation of the piperidine ring.
The various substituents on the piperidine nitrogen are
shown in Table 2. In this series, the 2-substituent was
®xed to the amino group taking into account both the
activity and solubility of the compound. Acyl deriva-
tives (8e±j) were tolerated despite the unsubstituted sec-
ondary amine (7), alkyl amino derivatives (8a±d) and
amino derivatives (11a±c) directly substituted at the

N. Fujiwara et al. / Bioorg. Med. Chem. Lett. 10 (2000) 1317±1320
1319
Scheme 1. Reagents and conditions: (i) BzCl, Et3N, THF, 0 ꢀC, 95%; (ii) aniline, BCl3, AlCl3, (CHCl2)2, 90 ꢀC, 75%; (iii) KOCN, AcOH, 60 ꢀC,
71%; (iv) HCl/Et2O; (v) H2NCN, 50 ꢀC, 97%; (vi) t-BuONO, SbCl3, (CHCl2)2, 60 ꢀC, 32%; (vii) H2, Pd/C, AcONa, MeOH, rt, 45%; (viii) 6N-
NaOH, EtOH, re¯ux, 82%; (ix) R1X, Et3N, 0-80 ꢀC, DMF, 20±41% (for 8a±c); cyclohexanone, NaB(CN)H3, HCl-MeOH, rt, 45% (for 8d); Ac2O,
Et3N, CHCl3, 0 ꢀC, 76% (for 8e); RCOCl, Et3N, 0 ꢀC, CHCl3, 45±69% (for 8f±j).
Scheme 3. Reagents and conditions: (i) SOCl2, CHCl3, re¯ux; (ii)
Scheme 2. Reagents and conditions: (i) aniline, 1-methylpiperazine or
R5COCH3 /LDA, THF, 70 ꢀC, 38±54%; (iii) guanidine hydrochlo-
piperidine, THF, rt, 75±95%; (ii) NH3, EtOH, 90 ꢀC, autoclave, 21±
ride, K2CO3, pyridine, 110 ꢀC, 74±77%.
47%.
Scheme 4. Reagents and conditions: (i) SOCl2, CHCl3, re¯ux; (ii) 4-methoxyphenylacetone/LDA, THF, 70 ꢀC, 35% (for 13c), 35% (for 13d); (iii)
guanidine hydrochloride, K2CO3, pyridine, 110 ꢀC, 45% (for 14c), 7% (for 14d); (iv) 6N-NaOH, EtOH, re¯ux, 79%; (v) R6COCl, Et3N, CH2Cl2 or
CHCl3, 0 ꢀC, 68±100% (for 16a±g, 16i±m, 16s); R6CO2H, HOBt, WSC, CHCl3, rt, 86±100% (for 16h, 16n±r, 16t±x).
Substitutions at the piperidine nitrogen were further
examined with the benzylpyrimidine derivative 14c as
the template. The various amide substituents are shown
in Table 4. Alkanoyl derivatives (16a±f) were tolerated
but did not produce more potent compounds. The
mono- and di-substituted benzoyl analogues (16g±r)
generally enhanced potency. Of these compounds, 16i,
16k-o, 16q and 16r had high potencies (IC50<1 mM).
There was no marked di€erence in activity produced in
terms of the electron-withdrawing or electron-donating
nature of the benzoyl substitution (16g±i versus 16j±l).
The position of the substituent may, however, be impor-
tant to the increase in activity in the order of para>-
meta>ortho. Phenylacetyl analogues (16s±x) showed
activity that was weaker than that of the corresponding
substituted benzoyl analogues.
In conclusion, a number of analogues of the piper-
idylquinazoline and piperidylpyrimidine derivatives
were evaluated for their abilities to inhibit TNF-a pro-
duction. Starting from weakly active lead 3, we have
identi®ed potent inhibitors in both types of compounds.
There is not marked di€erence in activity between the two
structures, but the pyrimidine analogues are favorable
from the view point of toxicity.30 Therefore e€orts to
expand the structure±activity relationship are in progress
using pyrimidines as substrates.
Acknowledgements
We thank Mr. Y. Ueda, Ms. F. Hirota and Ms. A. Yama-
saki for providing biological data; Dr. E. Nakajo and

1320
N. Fujiwara et al. / Bioorg. Med. Chem. Lett. 10 (2000) 1317±1320
Mr. F. Antoku for their support and helpful discussions.
We also are deeply grateful to Dr. S. Morooka for his
most helpful discussions of our work.
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