Synthesis of N-Pyridinyl(methyl)-1,2-dihydro-4-hydroxy-2-oxoquinoline-3-carboxamides and analogues and their anti-inflammatory activity in mice and rats

Article abstract of DOI:10.1211/0022357011775505

The topical anti-inflammatory activity of a series of N-pyridinyl(methyl)1,2-dihydro-4-hydroxy-2-oxoquinoline-3-carboxamides, analogues of roquinimex, has been evaluated by measuring their inhibitory effect in the phorbol myristate acetate (PMA)-induced m

Full text of DOI:10.1211/0022357011775505

Journal of
Pharmacy and Pharmacology
JPP 2001, 53: 417–423
# 2001 The Authors
Received June 21, 2000
Accepted September 7, 2000
ISSN 0022-3573
Synthesis of N-Pyridinyl(methyl)-1,2-dihydro-4-hydroxy-
2-oxoquinoline-3-carboxamides and analogues and
their anti-inflammatory activity in mice and rats
X. Collin, J. M. Robert, M. Duflos, G. Wielgosz, G. Le Baut,
C. Robin-Dubigeon, N. Grimaud, F. Lang and J. Y. Petit
Abstract
The topical anti-inflammatory activity of a series of N-pyridinyl(methyl)1,2-dihydro-4-hydroxy-
2-oxoquinoline-3-carboxamides, analogues of roquinimex, has been evaluated by measuring
their inhibitory effect in the phorbol myristate acetate (PMA)-induced mouse ear swelling test,
used as a screening test.
All the eight carboxamides tested (9–16) exhibited significant inhibitory activity at 0.4 and
0.2 mM kg 1. The most potent compound, the 6-bromo derivative 12, induced a 73% inhibition
−
at 0.2 mM kg 1. Pharmacomodulation was carried out by heterocycle opening and molecular
−
simplification leading to pentafluorobenzoylacetamide 17, pentafluorocinnamamides 18 and
19, and pentafluorobenzaldimines 20 and 21. All the five compounds exerted a reduction in
swelling (49–63% at 0.2 mM kg 1) comparable with ibuprofen (56%). Anti-inflammatory
−
activity of the most efficient compounds was evaluated by carrageenan-induced rat paw
oedema inhibition. The pentafluorobenzaldimine 20 showed the highest activity with an
1
−
inhibition percentage of 85% at 0.2 mM kg
.
Introduction
Laboratoires de Chimie
Organique et de Chimie
Therapeutique, Faculte de
Pharmacie, 1 rue Gaston Veil,
44035 Nantes, France
Classical non-steroidal anti-inflammatory drugs are not always effective at control-
ling chronic inflammatory diseases such as rheumatoid arthritis, inflammatory
bowel disease and psoriasis at concentrations compatible with their gastrointestinal
and renal toxicity. In these pathologies, tumour necrosis factor-α (TNF-α) has been
shown to be one of the main cytokines recruiting activated immune and inflam-
matory cells to the site of lesions, thereby amplifying and perpetuating the
inflammatory state (Brennan et al 1995). That is why, for perhaps the first time since
cyclooxygenase, researchers of inflammatory disease have been provided with a
validated target on which they could focus their efforts.
X. Collin, J. M. Robert,
M. Duflos, G. Wielgosz,
G. Le Baut
Laboratoire de Pharmacologie,
Faculte de Pharmacie, 1 rue
Gaston Veil, 44035 Nantes,
France
A new class of anti-inflammatory compounds that inhibit TNF-α production are
the cytokine suppressing anti-inflammatory drugs, typified by the 5-(4-fluoro-
phenyl)-4-(4-pyridinyl)imidazole SKF-86002 (1, Figure 1) with an ID50 value of
C. Bobin-Dubigeon, N. Grimaud,
F. Lang, J. Y. Petit
approximately 32 mg kg 1 (Black et al 1997).
−
We described previously the synthesis, anti-inflammatory activity and TNF-α
inhibitory activity of N-(4,6-dimethylpyridin-2-yl)aryl and heteroarylcarboxamides
(Lang et al 1995; Robert et al 1995; Vernhet et al 1997). The furan-2-carboxamide
2 was the most interesting derivative in that series, with an inhibition percentage of
Correspondence: X. Collin,
Laboratoires de Chimie
Organique et de Chimie
Therapeutique, Faculte de
Pharmacie, 1 rue Gaston Veil,
44035 Nantes, France.
1
−
87% at 0.4 mmol kg in carrageenan-induced rat paw oedema. It also inhibited
417

418
X. Collin et al
TNF-α production with an IC50 inferior to that of
thalidomide: approximately 70 vs 200 µ (Sampaio et
al 1991).
More recently we studied a series of N-azaaryl-
(alkyl)phthalimides incorporating amino (alkyl)pyri-
dines (Collin et al 1998). N-(3-pyridinylmethyl)-
tetrafluorophthalimide 3 was found to be the most
potent TNF-a production inhibitor (IC50 l 6 µ), and
the most efficient in-vivo anti-inflammatory compound
in phorbol myristate acetate (PMA)-induced mouse ear
1
2
3
4
Figure 1 Chemical structures of anti-inflammatory compounds
inhibiting TNF-α production.
1
−
oedema test (63% at 0.2 m kg ) and in carrageenan-
1
−
induced rat paw oedema (ID50 l 0.14 mmol kg ).
Roquinimex (4), a 1,2-dihydro-4-hydroxy-2-oxo-
quinoline-3-carboxamide, could represent another pos-
sible lead compound for the above purpose. Interest in
this TNF-α inhibitor for the treatment of inflammatory
bowel disease and psoriasis has been claimed (Anony-
mous 1997).
Table 1 Inhibition of phorbol myristate acetate-induced mouse ear
oedema of N-pyridinyl(methyl)-1,2-dihydro-4-hydroxy-2-oxoquino-
line-3-carboxamides 9–16.
On the basis of these findings we have focused
on synthesizing a series of N-pyridinyl(methyl)-1,
2-di-hydro-4-hydroxy-2-oxoquinoline-3-carboxamides
(9–16, Table 1). Preliminary pharmacomodulation was
carried out by nitrogen and homocycle substitution and
then by heterocycle opening followed by molecular
simplification leading to a β-phenyl-β-ketoamide (17),
cinnamamides (18, 19) and arylimines (20, 21).
Due to their poor solubility in water and ethanol, the
effect of most of these compounds on the in-vitro
production of TNF-α by activated peritoneal macro-
phages could not be quantified as described previously
(Collin et al 1998). Their anti-inflammatory activity was
then evaluated in PMA-induced mouse ear oedema
assay (Carlson et al 1985), considered to be a relevant
model of human psoriasis, used as a screening test. The
most potent compounds were tested using the carra-
geenan-induced rat paw oedema model (Winter et al
1962).
Inhibition (%)a
Compound
Dose (mm–kg–1
)
X
R1
R
0.2
0.4
9
H
H
62±6
68±4
60±6
75±2
10
11
12
H
CH3
H
44±2
60±2
Cl
Br
H
73±3
92±4
13
H
H
59±4
58±6
69±2
55±1
56±4
80±4
60±5
80±2
73±6
86±6
Materials and Methods
14
H
CH3
H
Chemistry
15
Cl
Br
Melting points were determined on a Tottoli-Buchi
apparatus and were uncorrected. Structures were sup-
ported by data from IR, 1H NMR and mass spectra. IR
spectra were recorded on a Perkin Elmer-Paragon PC
1000 spectrometer as potassium bromide discs. 1H
NMR spectra were recorded on a Bruker AC 250
spectrometer(250fs,25MHz)usingCDCl3ord6-(CH3)2SO
as solvent. Chemical shifts refer to tetramethylsilane,
which was used as internal reference; coupling constants
H
16
Ibuprofen
a Inhition is expressed as the mean of five measures.

419
Synthesis and anti-inflammatory activity of some carboxamides
are in Hz. Mass spectra were recorded on a double beam (d, J l 2.3, 1H, Pyr-4H), 11.73 (s, 1H, NH), 14.25 (s,
Varian Mat 112 spectrometer; ionization energy 70 eV. 1H, OH).
Analytical TLC was performed on precoated silica-gel
aluminium plates (0.2 mm, GF254, E Merck). Spots
were located by UV illumination. Sodium sulfate or
Synthesis of 1,2-dihydroquinoline-3-
carboxamides
phosphorus pentoxide was used as the drying agent.
Column chromatography was conducted on silica gel
N-(4,6-Dimethylpyridin-2-yl)-1,2-dihydro-4-hydroxy-2-
oxoquinoline-3-carboxamide (9). Method ii.
A mixture of 2-amino-4,6-dimethylpyridine (0.8 g,
(Kieselgel 60, 70–230 mesh, E Merck) and for delicate
separations a preparative centrifugally-accelerated thin
layer chromatography (Chromatotron 7924 T, Har-
6.6 mmol) and ethyl 1,2-dihydro-4-hydroxy-2-oxo-
risson Research, Palo Alto, CA) was used.
Starting materials were purchased from Aldrich
quinoline-3-carboxylate (5, 0.5 g, 2.2 mmol) in xylene
(20 mL) was refluxed for 2 h. The solution was cooled
Chimie (St Quentin-Fallavier, France), Acros (Noisy-
in an ice bath for 1 h. The resultant precipitate was
le-Grand, France) or Interchim (Montluçon, France).
collected, washed with xylene, diethyl ether and re-
crystallized from tetrahydrofurane–hexane (80:20)
1
−
(0.53 g, 78%); mp 315mC. IR (KBr), ν (cm ) 1685 (νC%O
amide), 1620 (νC%O lactam), 1575 (δNH). EI-MS m\z
(%) 309 (M, 9), 122 (100), 95 (15). 1H NMR (DMSOd6)
δ 2.36 (s, 3H, 4-CH3), 2.43 (s, 3H, 6-CH3), 6.96–8.04 (m,
6H, Ar-H, Pyr-5H, Pyr-3H), 12.18 (s, 1H, OH, CONH
or NH), 12.82 (s, 1H, OH, CONH or NH), 15.38 (s, 1H,
OH, CONH or NH).
Synthesis of intermediary ethyl quinoline-3-
carboxylates
Ethyl 1,2-dihydro-4-hydroxy-2-oxoquinoline-3-
carboxylate (5). Method i.
Condensation of diethyl malonate and isatoic anhydride
in the presence of sodium hydride in dry dimethyl-
formamide led to compound 5 (Hayashi et al 1993;
Ismaili 1995). Yield: 62%; mp 205mC (lit. 204mC). IR
N-(4,6-Dimethylpyridin-2-yl)-1,2-dihydro-4-hydroxy-1-
methyl-2-oxoquinoline-3-carboxamide (10). Method ii.
1
−
(KBr), ν (cm ) 1690 (νC%O ester), 1650 νC%O lactam).
1H NMR (CDCl3) δ 1.53 (t, J l 7.07, 3H, CH3), 4.53 (q,
J l 7.08, 2H, CH2), 7.19–8.09 (m, 4H, Ar-H), 11.65 (s,
1H, NH), 14.30 (s, 1H, OH).
1
−
Yield: 75%; mp 232mC. IR (KBr), ν (cm ) 1655 (νC%O
amide), 1595 (νC%O lactam), 1545 (δNH). EI-MS m\z
(%) 322 (M, 58), 122 (100), 95 (18). 1H NMR (CDCl3)
δ 2.36 (s, 3H, 4-CH3), 2.46 (s, 3H, 6-CH3), 3.70 (s, 3H, N-
CH3), 6.78 (s, 1H, Pyr-5H), 7.85 (s, 1H, Pyr-3H),
7.30–8.20 (m, 4H, Ar-H), 12.80 (s, 1H, OH or CONH),
15.20 (s, 1H, OH or CONH).
Ethyl 1,2-dihydro-4-hydroxy-1-methyl-2-oxoquinoline-
3-carboxylate (6). Method i.
1
−
Yield: 69%; mp 103mC (lit. 105mC). IR (KBr), ν (cm )
1690 (νC%O ester), 1670 (νC%O lactam). 1H NMR
(CDCl3) δ 1.43 (t, J l 7.12, 3H, CH3-CH2), 3.64 (s, 3H,
N-CH3), 4.48 (q, J l 7.11, 2H, CH2), 7.21–8.18 (m, 4H,
Ar-H), 14.19 (s, 1H, OH).
N-(4, 6-Dimethylpyridin-2-yl)-6-chloro-1, 2-dihydro-4-
hydroxy-2-oxoquinoline-3-carboxamide (11). Method
ii.
1
−
Yield: 63%; mp 323mC. IR (KBr), ν (cm ) 1670 (νC%O
Ethyl 6-chloro-1,2-dihydro-4-hydroxy-2-oxoquinoline-3-
carboxylate (7). Method i.
amide), 1625 (νC%O lactam), 1580 (δNH). EI-MS m\z
1
1
(%) 345 (Mj2, 3), 343 (M, 9), 122 (100), 95 (17). H
−
Yield: 57%. IR (KBr), ν (cm ) 1685 (νC%O ester), 1620
(νC%O lactam). 1H NMR (DMSOd6) δ 1.33 (t, J l 7.10,
3H, CH3-CH2), 4.36 (q, J l 7.57, 2H, CH2), 7.32 (d, J l
8.8, 1H, Ar-8H), 7.70 (dd, J l 8.8, 2.3, 1H, Ar-7H), 7.92
(d, J l 2.3, 1H, Pyr-4H), 11.72 (s, 1H, NH), 14.30 (s,
1H, OH).
NMR (CF3COOD) δ 2.69 (s, 3H, 4-CH3), 2.84 (s, 3H, 6-
CH3), 7.38 (s, 1H, Pyr-5H), 7.48 (d, J l 8.9, 1H, Ar-8H),
7.51 (s, 1H, Pyr-3H), 7.86 (dd, J l 8.7, 2.6, 1H, Ar-7H),
8.34 (d, J l 1.9, 1H, Ar-5H).
N-(4, 6-Dimethylpyridin-2-yl)-6-bromo-1,2-dihydro-4-
Ethyl 6-bromo-1,2-dihydro-4-hydroxy-2-oxoquinoline-3- hydroxy-2-oxoquinoline-3-carboxamide (12). Method
carboxylate (8). Method i. ii.
1
1
−
−
Yield: 73%. IR (KBr), ν (cm ) 1685 (νC%O ester), 1620 Yield: 65%; mp 328mC. IR (KBr), ν (cm ) 1690 (νC%O
(νC%O lactam). 1H NMR (DMSOd6) δ 1.34 (t, J l 7.15, amide), 1620 (νC%O lactam), 1565 (δNH). EI-MS m\z
3H, CH3-CH2), 4.34 (q, J l 7.20, 2H, CH2), 7.27 (d, J l (%) 388 (Mj2, 23), 386 (M, 24), 122 (100), 95 (14). 1H
8.8, 1H, Ar-8H), 7.79 (dd, J l 8.8, 2.4, 1H, Ar-7H), 8.18 NMR (CF3COOD) δ 2.68 (s, 3H, 4-CH3), 2.83 (s, 3H, 6-

420
X. Collin et al
CH3), 7.38 (s, 1H, Pyr-5H), 7.41 (m, 1H, Ar-8H), 7.50 (s, pressure. Chromatography of the crude oily product
1H, Pyr-3H), 7.98 (m, 1H, Ar-7H), 8.49 (m, 1H, Ar-5H). on a preparative centrifugally-accelerated thin layer
chromatograph using dichloromethane–ethanol (95:5)
N-(3-Methylpyridinyl)-1, 2-dihydro-4-hydroxy-2-
oxoquinoline-3-carboxamide (13). Method ii.
as eluent yielded 2.08 g (83%) of pure compound; mp
1
−
134mC. IR (KBr), ν (cm ) 3280 (νOH), 3220 (νNH),
1
−
Yield: 80%; mp 267mC. IR (KBr), ν (cm ) 1660 νC%O 1660 (νC%O), 1530 (δNH), 1235 (combined NH\CN).
amide), 1615 νC%O lactam), 1560 (δNH). EI-MS m\z EI-MS m\z (%) 358 (M, 100), 195 (21), 163 (21), 122
(%) 295 (M, 100), 188 (19), 161 (27), 107 (100), 92 (29). (100), 106 (12). H NMR (DMSOd6) δ 2.29 (s, 3H,
1
1H NMR (DMSOd6) δ 4.66 (d, J l 6.05, 1H, CH2), 4-CH3), 2.33 (s, 3H, 6-CH3), 4.17 (s, 1H, CH-CO), 6.10
7.29–8.63 (m, 8H, Ar-H, Pyr-H), 10.75 (m, 1H, CONH), (s, 1H, Pyr-5H), 7.80 (s, 1H, Pyr-3H), 10.73 (s, 1H,
11.92 (s, 1H, OH or NH), 11.94 (s, 1H, OH or NH).
CONH), 11.56 (s, 1H, OH).
N-(3-Methylpyridinyl)-1, 2-dihydro-4-hydroxy-1-
methyl-2-oxoquinoline-3-carboxamide (14). Method ii.
Synthesis of cinnamamides
1
−
Yield: 88%; mp 162mC. IR (KBr), ν (cm ) 1675 νC%O
N-(4,6-Dimethylpyridin-2-yl)pentafluorocinnamamide
(18). Method iv.
amide), 1595 (νC%O lactam), 1555 (δNH). EI-MS m\z
(%) 309 (M, 20), 292 (12), 175 (49), 107 (95), 92 (15). H
1
A
solution of pentafluorocinnamic acid (1.36 g,
NMR (CDCl3) δ 3.68 (s, 3H, N-CH3), 4.67 (d, J l 5.97,
1H, CH2), 7.29–8.64 (m, 8H, Ar-H, Pyr-H), 10.79 (m,
1H, CONH), 14.90 (s, 1H, OH).
5.7 mmol), 2-amino-4,6-dimethylpyridine (0.69 g,
5.7 mmol) and triethylamine (2.4 mL, 17.1 mmol) in dry
1,2-dichloroethane (60 mL) was cooled in an ice bath.
Phenyl dichlorophosphate (0.85 mL, 5.7 mmol) was
added dropwise. The mixture was stirred for 24 h at
room temperature. The solvent was removed under
reduced pressure. The residue was purified by column
chromatography using dichloromethane–ethanol (98:2)
as eluent. Crystallization from diisopropyl ether
afforded 1.81 g of pure product. Yield: 81%; mp 154mC.
N-(3-Methylpyridinyl)-6-chloro-1,2-dihydro-4-
hydroxy-2-oxoquinoline-3-carboxamide (15). Method
ii.
1
−
Yield: 80%; mp 266mC. IR (KBr), ν (cm ) 1660 νC%O
amide), 1605 (νC%O lactam), 1560 (δNH). EI-MS m\z
(%) 331 (Mj2, 20), 329 (M, 56), 107 (100), 92 (14). 1H
NMR (DMSOd6) δ 4.66 (d, J l 6.05, 1H, CH2), 7.40 (d,
J l 8.7, 1H, Ar-8H), 7.42 (m, 1H, Pyr-5H), 7.73 (dd,
J l 8.8, 2.4, 1H, Ar-7H), 7.81 (m, 1H, Pyr-4H), 7.93
(d, J l 2.4, 1H, Ar-5H), 8.50 (m, 2H, Pyr-2H, Pyr-6H).
1
−
IR (KBr), ν (cm ) 3420 (νNH), 1700 (νC%O), 1535
(δNH), 1430 (combined NH\CN). EI-MS m\z (%) 342
(M, 100), 221 (28), 193 (60), 147 (83), 122 (55), 77 (9). 1H
NMR (CDCl3) δ 2.36 (s, 3H, 4-CH3), 2.43 (s, 3H,
6-CH3), 6.80 (s, 1H, Pyr-5H), 6.84 (d, J l 15.8, 1H,
ClCH-CO), 7.74 (d, J l 15.9, 1H, CH%C-CO),7.98 (s,
1H, Pyr-3H), 8.66 (s, 1H, CONH).
N-(3-Methylpyridinyl)-6-bromo-1,2-dihydro-4-
hydroxy-2-oxoquinoline-3-carboxamide (16). Method
ii.
1
−
Yield: 81%; mp 264mC. IR (KBr), ν (cm ) 1690 νC%O
N-(3-Methylpyridinyl)pentafluorocinnamamide (19).
Method iv.
amide), 1615 (νC%O lactam), 1565 (δNH). EI-MS m\z
1
(%) 374 (Mj2, 33), 372 (M, 32), 107 (100). H NMR
1
−
Yield: 75%; mp 94 mC. IR (KBr), ν (cm ) 3305 (νNH),
(CF3COOD) δ 5.05 (m, 1H, CH2), 7.47 (m, 1H, Ar-8H),
7.93 (m, 1H, Ar-7H), 8.15 (m, 1H, Pyr-5H), 8.43 (m, 1H,
Ar-7H), 8.76 (m, 1H, Pyr-4H), 8.82–9.01 (m, 2H, Pyr-
2H, Pyr-6H).
1670 (νC%O), 1535 (δNH), 1430 (combined NH\CN).
EI-MS m\z (%) 328 (M, 100), 221 (84), 193 (80), 107
(53), 92 (25). 1H NMR (CDCl3) δ 4.50 (s, 1H, CH2), 6.72
(d, J l 16.0, 1H, C%CH-CO), 6.96 (s, 1H, CONH), 7.22
(m, 1H, Pyr-5H), 7.57 (d, J l 16.0, 1H, CH%C-CO),
7.65 (m, 1H, Pyr-4H), 8.43 (m, 2H, Pyr-6H, Pyr-2H).
Synthesis of β-ketoamide 17
N-(4,6-Dimethylpyridin-2-yl)
pentafluorobenzoylacetamide (17). Method iii.
2-Hydroxypyridine (0.28 g, 2.9 mmol) was added to
Synthesis of imines
a solution of 2-amino-4,6-dimethylpyridine (1.7 g, N-(3-Methylpyridinyl)pentafluorobenzaldimine (21).
14 mmol) and ethyl pentafluorobenzoylacetate (1.4 mL, Method v.
7 mmol) in dry toluene (30 mL). The mixture was Sodium sulfate (5 g, 35 mmol) was added to a solution
refluxed for 6 h. The solvent was removed under reduced of pentafluorobenzaldehyde (3.92 g, 20 mmol) and 3-

421
Synthesis and anti-inflammatory activity of some carboxamides
i
ii
5–8
9–16
Figure 2 Synthetic pathway to N-pyridinyl(methyl)1,2-dihydro-4-hydroxy-2-oxoquinoline-3-carboxamides. Reagents: i. diethyl malonate,
sodium hydride, DMF, 130mC, 2.5 h; ii. xylene, reflux, 2 h.
(aminomethyl)pyridine (2.03 mL, 20 mmol) in dry 1,2- were orally administered 1 h before PMA application
dichloroethane (15 mL). The mixture was refluxed for (treated animals). Ear thickness was measured with a
3 h. The solvent was removed under reduced pressure. model micrometer gauge (Oditest Kroeplin) 3.5 h after
The solid collected was recrystallized from ethyl acetate PMA treatment. Ear oedema was calculated by sub-
1
−
(4.8 g, 84%); mp 98mC. IR (KBr), ν (cm ) 1665 (νC%N). tracting the thickness of the left ear (vehicle) from the
EI-MS m\z (%) 286 (M, 17), 180 (10), 119 (62), 92 (100), thickness of the right ear (treatment) and was expressed
65 (60), 39 (30). 1H NMR (CDCl3) δ 4.91 (s, 1H, CH2), as an increase in ear thickness. The percentage of
7.30 (m, 1H, Pyr-5H), 7.70 (m, 1H, Pyr-4H), 8.54 (m, inhibition of the inflammatory reaction was determined
1H, Pyr-6H), 8.56 (s, 1H, CH%N), 8.60 (m, 1H, Pyr-2H). for each animal by comparison between ear oedema of
treated and non-treated animals.
Method vi.
A
Carrageenan-induced rat paw oedema.
solution of pentafluorobenzaldehyde (3.92 g,
Anti-inflammatory activity against carrageenan-in-
duced rat paw oedema was assayed in adult male Wistar
CF rats (180–220 g) according to the method of Winter
et al (1962) with slight modifications. The drugs were
orally administered 1 h before injection of 0.05 mL of a
1% suspension of carrageenan saline into the sub-
cutaneous tissue of one hind paw. The other hind paw
was injected in the same way with 0.05 mL of a saline
solution. Rats were fasted 24 h before the experiment
and water (1.5 mL\100 g body weight) was orally ad-
ministered twice before injections (20 h and 4 h). The
volume of both hind paws of the control and treated
animals was measured with a plethysmograph, 3 h after
injection. Rats were kept in the same experimental
conditions. The inhibition percentage of the inflamma-
tory reaction was determined for each animal by com-
parison with controls, and calculated by the formula
I(%) l 100i(1kdt\dc), where dt is the difference in
paw volume in the drug-treated group and dc the
difference in paw volume in the control group.
20 mmol) and 3-(aminomethyl)pyridine (2.03 ml,
20 mmol) in benzene (30 mL) was refluxed for 6 h using
a Dean-Stark trap to separate water. After removal of
the solvent under reduced pressure, the crude oily imine
was dissolved in the minimum of ethyl acetate and
crystallized by slow addition of petroleum ether. Beige
crystals (5.4 g; 95%) were obtained.
N-(4,6-Dimethylpyridin-2-yl)pentafluorobenzaldimine
(20). Method vi.
1
−
Yield: 72%; mp 86mC. IR (KBr), ν (cm ) 1605 (νC%N).
1
EI-MS m\z (%) 300 (M, 10), 107 (100). H NMR
(CDCl3) δ 2.36 (s, 3H, 4-CH3), 2.53 (s, 3H, 6-CH3), 6.95
(s, 1H, Pyr-5H), 7.02 (s, 1H, Pyr-3H), 9.31 (s, 1H,
CH%N).
Pharmacology
Acute phorbol ester-induced mouse ear-swelling test.
Introduction of mouse ear oedema was based on the
method of Carlson et al (1985) with some modifications.
Groups of five male Swiss mice (20–25 g) were fasted
24 h before the experiments and maintained in suitable
environmental conditions throughout the experiments.
Phorbol-12-myristate-13-acetate (PMA) was dissolved
Results and Discussion
Chemistry
in aqueous ethanol 80% at a concentration of N-Pyridinyl(methyl)-1,2-dihydro-4-hydroxy-2-oxo-
1
250 µg mL and 10 µL was applied topically to the quinoline-3-carboxamides (9–16) were prepared by am-
−
anterior and posterior surfaces on the right ear of each inolysis of the corresponding esters in refluxing xylene,
mouse. Left ear (control) received the vehicle (10 µL as outlined in Figure 2 and according to methods
aqueous ethanol 80%). The compounds under study described by Clemence et al (1988). As previously ob-

422
X. Collin et al
Table 2 Inhibition of phorbol myristate acetate-induced mouse ear
oedema of N-pyridinyl(methyl)amides 17–19 and imines 20 and 21.
iii
Inhibition (%)a
Compound
Dose (mm–kg–1
)
17
Figure 3 Synthesis of N-(3-methylpyridinyl)β-ketoamide 17. Re-
agent: iii. 2-hydroxypyridine, toluene, reflux, 6 h.
R
0.2
0.4
63±3
82±2
17
iv
18
19
60±3
62±4
86±1
79±4
18, 19
Figure 4 Synthesis of N-pyridinyl(methyl)cinnamamides. Reagent:
iv. phenyl dichlorophosphate, TEA, 1.2-dichloroethane, room tem-
perature, 24 h.
20
52±9
49±6
56±4
79±3
78±5
86±6
21
v or vi
20, 21
Ibuprofen
Figure
5
Synthesis of N-pyridinyl(methyl)benzaldimines. Re-
agents: v. sodium sulfate, 1,2-dichloroethane, reflux, 3 h; vi. benzene,
Dean Stark, reflux, 6 h.
a Inhibition is expressed as the mean ± of five measures.
served (Collin et al 1999), yields were ruled by nucleo-
philicity of the starting amines: β-picolylamine afforded
compounds 13–16 in 80–88% yields whereas 6-amino-
2,4-lutidine led to compounds 9–12 in only 63–78%
yields. The synthesis of intermediary ethyl 1,2-dihydro-
4-hydroxy-2-oxoquinoline-3-carboxylates (5–8) was
carried out by condensing corresponding isatoic an-
hydrides with diethylmalonate in the presenceof sodium
hydride (Hayashi et al 1993; Ismaili 1995).
the presence of triethylamine in 1,2-dichloroethane, at
room temperature.
N-Pyridinyl(methyl)pentafluorobenzaldimines (20
and 21) were obtained by reacting pentafluoro-
benzaldehyde with appropriate amines (Figure 5). The
use of a Dean Stark to separate formed water provided
compound 21 in better yield (95%) than the sodium
sulfate method (84%).
Aminolysis of ethyl pentafluorobenzoylacetate in re-
fluxing toluene in presence of 2-hydroxypyridine as a
bifunctional catalyst (Openshaw & Whittaker 1968) led All the quinoline-3-carboxamides exhibited significant
Pharmacology
to β-ketoamide 17 in good yield (83%) (Figure 3). For activity in the PMA-induced ear swelling test at 0.4 and
1
this compound, H NMR data were in favour of a 0.2 m kg (Table 1. N-Methylation led to less active
1
−
preponderant (" 95%) enol structure. molecules 10 and 14. Among the four 7-halogenated
N-Pyridinyl(methyl)pentafluorocinnamamides (18 derivatives (11, 12, 15 and 16), 12 was the most potent
and 19) were synthesized by condensation of corre- (inhibition percentage of 73% at 0.2 m kg 1 and 92%
−
1
sponding acids with appropriate amines, as outlined in at 0.4 m kg ), showing higher activity than ibuprofen
−
1
1
−
−
Figure 4, using the method which afforded the best (56% at 0.2 m kg and 86% at 0.4 m kg ). In the
results in previous studies (Collin et al 1999): phenyl series of N-pyridinyl(methyl)amides and imines in-
dichlorophosphate activation of the carboxylic acid in corporating a pentafluorophenyl moiety (Table 2), all

423
Synthesis and anti-inflammatory activity of some carboxamides
Table 3 Inhibition of carrageenan-induced rat paw oedema by the
−
most potent compounds (0.2 m kg ).
Carlson, R. P., O’Neil-Davis, L., Chang, J., Lewis, A. J. (1985)
Modulation of mouse ear edema by cyclooxygenase and
lipooxygenase inhibitors and other pharmacologic agents.
Agents Actions 17: 197–204
1
Compound
Inhibition (%)a
Clemence, F., Le Martret, O., Delevallee, F., Benzoni, J.,
Jouanen, A., Jouquey, S., Mouren, M., Deraedt, R. (1988)
4-Hydroxy-3-quinolinecarbox-amides with antiarthritic
and analgesic activities. J. Med. Chem. 31: 1453–1462
Collin, X., Robert, J. M., Robert-Piessard, S., Le Baut, G.,
Bobin-Dubigeon, C., Vernhet, L., Lang, F., Petit, J. Y.
(1998) Synthesis and potent tumor necrosis factor-α pro-
duction inhibitory activity of N-pyridinylphthalimides and
derivatives. Pharm. Pharmacol. Commun. 4: 27–30
Collin, X., Robert, J. M., Robert-Piessard, S., Le Baut, G.,
Bobin-Dubigeon, C., Grimaud, N., Lang, F., Petit, J. Y.
(1999) N-pyridinyl(alkyl)polyhalogenobenzamides acting
as TNF-α production inhibitors. Pharm. Pharmacol.
Commun. 5: 233–238
12
15p8
52p2
45p4
36p1
40p2
47p2
85p6
58p3
50p1
13
15
17
18
19
20
21
Ibuprofen
aInhibition is expressed as the meanps.e.m. of six measurements.
Hayashi, H., Miwa, Y., Ichikawa, S., Yoda, N., Miki, I., Ishii,
A., Kono, M., Yasuzawa, T., Suzuki, F. (1993) 5-HT3
receptor antagonists. 4-Hydroxy-3-quinolinecarboxylic
acid derivatives. J. Med. Chem. 36: 617–626
compounds were practically equipotent, with an in-
1
hibition percentage superior to 77% at 0.4 m kg .
−
To confirm the high potency as anti-inflammatory
agents of compounds 12, 13, 15, and 17–21 (inhibition
percentage superior or equivalent to 80% at
Ismaili, L. (1995) Synthese et approche immunopharmaco-
logique de derives de la 1,2-dihydroquinoleine-2-one.
These nm 25.96.03 university of Franche-Comte, France
Lang, F., Robert, J. M., Boucrot, P., Welin, L., Petit, J. Y.
(1995) New anti-inflammatory compounds that inhibit
tumor necrosis factor production: probable interaction with
protein kinase C activation. J. Pharmacol. Exp. Ther. 275:
171–176
0.4 m kg 1 in the PMA-induced ear oedema test) they
−
were evaluated in the carrageenan-induced rat paw
oedema model (Table 3). Although quinoline-3-car-
boxamide 12 was the most efficient in the PMA mouse
ear oedema, astonishingly it did not exert a significant
inhibitory effect on the carrageenan paw oedema, at
Openshaw, H. T, Whittaker, N. (1968) The synthesis of
emetine and related compounds. The utility of bi-functional
catalysts in amine-ester interactions. J. Chem. Soc. 89–91
Robert, J. M., Robert-Piessard, S., Courant, J., Le Baut, G.,
Robert, B., Lang, F., Petit, J. Y., Grimaud, N., Welin, L.
(1995) Non-carboxylic anti-inflammatory compounds. III.
N-(4,6-dimethyl-pyridin-2-yl)arylcarboxamides and aryl-
thiocarboxamides acting as brain oedema inhibitors. Eur. J.
Med. Chem. 30: 915–924
1
−
least not at 0.2 m kg (15%). The other compounds
all kept a high level of activity (13, 15, 18, 19, 20, 21:
1
45–85% at 0.2 m kg ), except compound 17 (36%).
−
Pentafluorobenzaldimine 20 induced the most signifi-
cant reduction in paw thickness (85%) and its level of
activity compared favourably with ibuprofen (50%).
Sampaio, E. N., Gallily, R., Cohn, Z. A., Kaplan, G. (1991)
Thalidomide selectively inhibits tumor necrosis factor-α
production by stimulated human monocytes. J. Exp. Med.
173: 699–703
References
Anonymous (1997) Roquinimex (Linomide). Drugs Future
22: 93–94
Vernhet, L., Petit, J. Y., Lang, F. (1997) An anti-inflammatory
benzamide derivative inhibits the protein kinase C (PKC)-
dependent pathway of Erk2 phosphorylation in murine
macrophages. J. Exp. Ther. 283: 358–365
Brennan, F. M., Maini, R. N., Feldmann, M. (1995) Cytokine
expression in chronic inflammatory disease. Br. Med. Bull.
5: 368–384
Black, R. A., Bird, T. A., Mohler, M. M. (1997) Agents that
block TNF-α synthesis or activity. Annu. Rep. Med. Chem.
32: 241–250
Winter, C. A., Risley, E. A., Nuss, G. W. (1962) Carrageenin-
induced edema in hind paw of rat as an assay for anti-
inflammatory drugs. Proc. Soc. Exp. Biol. Med. 11: 544–547