Synthesis and biological testing of N-aminoimidazole-based p38α MAP kinase inhibitors

Article abstract of DOI:10.1002/cmdc.201000114

The p38 mitogen-activated protein (MAP) kinase a plays α central role in the regulation of cellular responses such as differentiation, proliferation, apoptosis, and inflammation. Inhibition of p38 results in decreased synthesis of pro-inflammatory cytokines. To date, diverse p38α inhibitors are in phase II clinical trials for numerous cytokine-dependent diseases. 2-Sulfanylimidazole derivatives offer advantages over the prototype inhibitor SB 203580, including fewer cytochrome P450 interactions and better kinetic properties. The aim of this study was to develop novel 1,2,4,5-tetrasubstituted pyridinylimidazoles with acyl residues at the imidazole N1 position that can interact with the kinase's hydrophobic region II (HR II) or sugar pocket (SP) to improve both selectivity and activity. The substitution pattern was optimized by variation of the acyl moiety at the N1 position of the N-aminoimidazole core. Acylation of the amino function was used for optimization and led to potent p38α MAPK inhibitors.

Full text of DOI:10.1002/cmdc.201000114

MED
DOI: 10.1002/cmdc.201000114
Synthesis and Biological Testing of N-Aminoimidazole-
Based p38a MAP Kinase Inhibitors
Claudia Bracht,[a] Dominik R. J. Hauser,[a, b] Verena Schattel,[a] Wolfgang Albrecht,[b] and
Stefan A. Laufer*[a]
The p38 mitogen-activated protein (MAP) kinase a plays a cen-
tral role in the regulation of cellular responses such as differen-
tiation, proliferation, apoptosis, and inflammation. Inhibition of
p38 results in decreased synthesis of pro-inflammatory cyto-
kines. To date, diverse p38a inhibitors are in phase II clinical
trials for numerous cytokine-dependent diseases. 2-Sulfanylimi-
dazole derivatives offer advantages over the prototype inhibi-
tor SB 203580, including fewer cytochrome P450 interactions
and better kinetic properties. The aim of this study was to de-
velop novel 1,2,4,5-tetrasubstituted pyridinylimidazoles with
acyl residues at the imidazole N1 position that can interact
with the kinase’s hydrophobic region II (HR II) or sugar pocket
(SP) to improve both selectivity and activity. The substitution
pattern was optimized by variation of the acyl moiety at the
N1 position of the N-aminoimidazole core. Acylation of the
amino function was used for optimization and led to potent
p38a MAPK inhibitors.
Introduction
p38a is a member of the well-characterized mitogen-activated
protein (MAP) kinase family. This serine/threonine kinase is part
of the stress-activated signal transduction cascade and medi-
ates various extracellular stress signals to intracellular respons-
es such as cytokine production.[1,2] Depending on the stimulus
and cellular context, p38 can either protect cell viability or it
can promote apoptosis.[3] MAP kinases play a central role in
regulating the production of pro-inflammatory cytokines in-
cluding TNF-a, IL-1b, and IL-6, and are among the best-charac-
terized kinases in the inflammatory process.[4–7] p38 regulates
biosynthesis at both the transcriptional and translational
levels.[8,9]
prepared mainly to decrease interactions with CYP450 en-
zymes. However, appropriate substituents at this same position
also contributed to enhanced p38a binding and oral anti-cyto-
kine activity.[10,16,17]
Essential interactions with the ATP binding cleft are shown
in Figure 2. Hydrogen bond interactions of the pyridinyl
moiety with the hinge region mainly yield activity. Selectivity is
gained by interactions of bulky lipophilic aryl residues such as
the 4-fluorphenyl moiety with the hydrophobic region I (HR I).
Thr106 serves as a gatekeeper in p38a MAPK, as related kinas-
es possess bulky residues at this position. Interactions with the
hydrophobic region II (HR II) improve both activity and selectiv-
ity. Further interactions with the sugar pocket (SP) and the
phosphate binding region (PB) are preferred positions to
modify physiochemical properties.[10,19,20]
In 1994 p38a MAP kinase (MAPK) was identified as a target
of pyridinylimidazole inhibitors.[8] Various well-known ATP-com-
petitive MAPK inhibitors have since been developed which are
derived from the prototype inhibitors SK&F 86002 and
SB 203580 (Figure 1).[10–12] Various potent and selective p38a in-
hibitors are currently in phase II clinical studies for rheumatoid
arthritis, psoriasis, inflammatory bowel diseases, neuropathic
pain, cancer, depression, and cardiovascular diseases.[13]
With respect to the pyridinylimidazoles, it was revealed that
2-sulfanylimidazoles offer advantages over SB 203580, such as
fewer cytochrome P450 (CYP450) interactions and improved ki-
netic properties.[14,15] Initially, N-substituted imidazoles were
Results and Discussion
Scaffold design
A recently published investigation of tetrasubstituted 2-acyla-
minopyridin-4-ylimidazoles showed that acylation of the 2-
amino function of pyridine results in potent inhibition of p38a
and enhanced metabolic stability.[21] This is in line with earlier
data obtained for Takeda’s clinical compound TAK-715.[13,22] An-
[a] C. Bracht, Dr. D. R. J. Hauser, V. Schattel, Prof. Dr. S. A. Laufer
Institute of Pharmacy, Department of Pharmaceutical and Medicinal
Chemistry, Eberhard-Karls-Universitꢀt Tꢁbingen
Auf der Morgenstelle 8, 72076 Tꢁbingen (Germany)
Fax: (+49)7071-29-5037
E-mail: stefan.laufer@uni-tuebingen.de
[b] Dr. D. R. J. Hauser, Dr. W. Albrecht
Figure 1. Prototype inhibitors SB 203580 and SK&F 86002.
c-a-i-r biosciences GmbH, Paul-Ehrlich-Str. 15, 72076 Tꢁbingen (Germany)
1134
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N-Aminoimidazole-Based p38a MAP Kinase Inhibitors
Chemistry
According to a previously described synthesis for tetrasubsti-
tuted imidazoles, alkyl residues may be introduced at the imi-
dazole N1 position using the appropriately substituted triazi-
nanes and a-hydroxyiminoketone.[25,26,28] Attempts to prepare
suitably substituted triazinanes failed. Therefore, a novel syn-
thesis was developed to construct N-[4-(4-fluorophenyl)-2-
methylthio-5-(pyridin-4-yl)-1H-imidazol-1-yl]amide compounds.
Attempts to introduce an amino function at the respective
unsubstituted pyridinylimidazole N1 position using a base for
deprotonation and the amination reagents o-(diphenylphos-
phinyl)hydroxylamine and various benzoylhydroxylamines
were not successful.[29,30] Following the procedure of Lagoja
Figure 2. Interactions of imidazole-1-ylamides as ATP-competitive com-
pounds with the ATP binding site of p38a MAPK as modified by Traxler and
Furet.[18] AB: adenine binding region, SP: sugar pocket, PB: phosphate bind-
ing region, HR I: hydrophobic region I (also called selectivity pocket) adja-
cent to Thr106, and HR II: hydrophobic region II, where the cleft opens to
the cytosol.
et al.,
N-[5-(4-fluorophenyl)-4-(pyridin-4-yl)-2-thioxo-1,2-dihy-
droimidazol-3-yl]acetamide was prepared (Scheme 1).[31] At-
tempts to prepare the S-methylated compound using methyl-
thiocyanate instead of potassium thiocyanate afforded no
product. Subsequent methylation with iodomethane and a
base such as potassium carbonate, sodium hydride, or sodium
bis(trimethylsilyl)amide, or methylation under Mitsunobu con-
ditions were also unsuccessful.
other clinical candidate is ASKA’s pyridazinylpyrazole AKP-001
(Figure 3).[23,24] In this case, the acyl function is translocated to
the imidazole N1 position. No structure–activity relationships
Scheme 1. Preparation of N-[5-(4-fluorophenyl)-4-(pyridin-4-yl)-2-thioxo-1,2-
dihydroimidazol-3-yl]acetamide following a protocol reported by Lagoja
et al.[31]
Figure 3. Clinical candidates pyridinylthiazole TAK-715 and pyrimidylpyrra-
zole AKP-001.
on acyl derivatives within the sulfanylimidazole series are
known yet. Only alkyl residues have been probed at the imida-
zole N1 position.[25,26] However, results of docking pyridinylimi-
dazoles into the ATP binding site of p38a MAPK (template PDB
ID: 1A9U) demonstrated that there should be sufficient space
in HR II for larger acyl residues.
Retrosynthetic cleavage of pyridine led to starting material.
Synthesis of 1,2,4-trisubstituted sulfanylimidazole was per-
formed by starting from benzaldehyde 1 and thiosemicarba-
zide 2 via the corresponding thiosemicarbazone. Subsequent
base-catalyzed methylation of the sulfur atom with iodome-
thane resulted in intermediate 3 (Scheme 2).[32,33] Dropwise ad-
dition of bromine in dichloromethane to a solution of 4-fluo-
roacetophenone 4 in dichloromethane afforded bromoaceto-
phenone 5.[34] The S-alkylated isomer of a thiosemicarbazone 3
and bromoacetophenone 5 were stirred at 758C in acetonitrile
together with sodium bicarbonate to obtain the 1,2,4-trisubsti-
tuted sulfanylimidazole 6 as a yellow precipitate.[35] After wash-
ing with water to remove the inorganic salts, the intermediate
product was obtained as analytically pure without further pu-
rification. The pyridinyl moiety was introduced according to a
procedure reported by Lantos et al.[36] Imidazole 6 was dis-
solved in a mixture of 1,2-dichloroethane and pyridine. Addi-
tion of ethyl chloroformate during ice cooling afforded the un-
stable intermediate 7, which was subsequently oxidized with
N-Aminoimidazoles have the advantage of offering interac-
tions with residues at the imidazole N1 position and also
through the NꢀH group as a hydrogen-bond donor. Until now,
substitution at N1 has often led to weaker interactions with
the CYP450 enzymes and has decreased inhibitory potency.[27]
Therefore, the aim of this study was to synthesize novel 4-fluo-
rophenylpyridylimidazol-1-ylamides that can interact with HR II
or the SP of p38a MAPK to improve both selectivity and activi-
ty.
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S. A. Laufer et al.
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in absolute N-methylpyrrolidone (NMP) at room temperature.
The activated imidazolide intermediates reacted with com-
pound 9 added at an oil bath temperature of 1208C to yield
the test compounds (general procedure A).
Urea compound 12a was prepared by stirring compound 9
and 1-fluoro-4-isocyanatobenzene dissolved in pyridine at
room temperature.[37] Again, pyridine serves as both solvent
and base.
Biological assays
All test compounds were initially screened in a competitive
non-radioactive p38a MAPK assay using the isolated enzyme
with ATP concentrations of 100 mm and the endogenous acti-
vation transcription factor-2 (ATF-2) as substrate.[38] SB 203580
served as an internal standard.
Previously mentioned 2-acylaminopyridin-4-ylimidazoles
showed inhibitory potency in the two- to three-digit nanomo-
lar range.[21] For the present study, we hypothesized that both
substituents at the pyridinyl C2 position and residues at the
imidazole N1 position are able to interact with HR II. Therefore
similar inhibitory potency was expected. Indeed, the 1-acylami-
no-5-pyridinylimidazoles showed inhibitory potency toward
p38a in the same range (Table 1).
Scheme 2. Preparation of 4-(4-fluorphenyl)-2-methylsulfanyl-5-pyridin-4-yli-
midazol-1-ylamine as a key compound for the synthesis of test compounds:
a) EtOH, 608C, H2O, room temperature, 30 min; b) K2CO3, CH3I, EtOH, room
temperature, 4 h; c) Br2, CH2Cl2, room temperature, 3 h; d) NaHCO3, CH3CN,
758C, 3 h; e) ethyl chloroformate, pyridine, CH2Cl2, 08C!room temperature,
2 h; f) sulfur, mesitylene, reflux, 3 h; g) N2H4·H2O, 2-methoxyethanol.
Various benzoic acid and acetic acid derivatives as well as a
urea residue were attached to the key intermediate 9. All var-
iants showed a significant increase in kinase inhibition. Bulky
residues such as the benzofuryl moiety of compound 11 i and
the phenoxyethyl moiety of compound 11 h improved inhibi-
sulfur in mesitylene to afford pyridinylimidazole 8.
Hydrazinolysis of the hydrazone with hydrazine hy-
drate in 2-methoxyethanol resulted in 4-(4-fluoro-
phenyl)-2-methylthio-5-(pyridin-4-yl)-1H-imidazol-1-
amine 9 as a key intermediate for the synthesis of a
series of test compounds. The free amino function at
the imidazole N1 position allowed amidation and for-
mation of urea products.
Amide compounds can be synthesized by using
activated carboxylic acids. Acetylated compound 11 a
was prepared by using 9 and the respective acetyl
chloride as well as with acetic anhydride (Scheme 3).
Acetylation with the acid chloride was performed
under ice cooling using pyridine both as solvent and
Scheme 3. Synthesis of test compounds 11 a–i and 12a: a) carboxylic acid chloride, pyri-
dine, 0–58C, 1 h; b) carboxylic acid anhydride, DMAP, reflux, 1 h; c) 5m HCl, room tem-
perature, 3.5 h; d) carboxylic acid, CDI, NMP; e) 1-fluoro-4-isocyanatobenzene, pyridine,
room temperature, 16 h.
base. The second option was carried out by holding
compound 9 at reflux in acetic anhydride with cata-
lytic amounts of 4-dimethylaminopyridine (DMAP).[21]
Both options led to mixtures of the mono- and diace-
tylated compounds 10a and 11 a and unreacted 9,
even with the acetylic acid chloride present in equimolar
amounts. The product 11 a was obtained either after flash
chromatography or after deacetylation when the respective di-
acetylated compound 10a was stirred in 5m hydrochloric acid
for one hour and subsequently neutralized with ammonia.
The other amide derivatives were prepared by activating the
respective carboxylic acids with N,N’-carbonyldiimidazole (CDI)
tion relative to compound 9 by twofold. Benzoic acid com-
pounds 11 b and 11 d as well as furyl compound 11 c showed
a sixfold improvement in inhibitory potency. Phenylacetic acid
derivative 11 e showed a greater than sevenfold increase in in-
hibitory potency, and the corresponding urea compound 12a
was even 13-fold more potent. The best inhibition of p38a in
the low nanomolar range was observed with inhibitors bearing
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N-Aminoimidazole-Based p38a MAP Kinase Inhibitors
Table 1. Test compounds and inhibition of p38a MAPK.
Compd
R
IC50 [mm][a]
9
H
1.875ꢁ0.09
11 a
0.840ꢁ0.10
11 b
0.314ꢁ0.03
11 c
11 d
0.308ꢁ0.03
0.242ꢁ0.11
11 e
11 f
0.244ꢁ0.03
0.058ꢁ0.00
Figure 4. Compound 11 f docked into the ATP binding site of p38a MAPK
(PDB ID: 3HL7).
11 g
11 h
0.095ꢁ0.01
1.080ꢁ0.28
of water displacement. The substituted acylimidazoles exhibit-
ed significant increases in kinase inhibition relative to the un-
substituted compound 9. Clearly the nonspecific hydrophobic
interactions play a significant role in binding affinity. In con-
trast, the substitution pattern of the residues appears to be
less important.
11 i
0.873ꢁ0.21
0.145ꢁ0.04
The respective substituted pyrimidylpyrazoles 13a and
13b[23,41] and isoxazoles 14a and 14b[42,43] were synthesized to
develop the most appropriate scaffold. Biological testing re-
vealed that the inhibitory potency of the sulfanylimidazoles is
almost as good as that of the pyrazole scaffold and better
than the isoxazole scaffold (Table 2).
12a
[a] Data reflect the mean ꢁSEM of three experiments. SB 203580 IC50
0.034ꢁ0.003 mm (n=12).
=
Conclusions
rigid residues, such as (2-chlorophenyl)acetic acid 11 f and 2-
phenylpropionic acid 11 g.
A novel synthesis for tetrasubstituted N-[4-(4-fluorphenyl)-2-
Test compounds were docked into the ATP binding site of
p38a MAPK (PDB ID: 3HL7) as induced by the Fit Docking pro-
tocol from Schrçdinger (Figure 4).[39] In the predicted binding
mode, the 4-fluorophenyl moiety is located deep within the se-
lectivity pocket as expected. The inhibitor is anchored to the
hinge region through a hydrogen bond between the acceptor
pyridine nitrogen atom and the NꢀH group of Met109. Imida-
zole N3 may serve as a hydrogen bond donor and form a
second hydrogen bond to the terminal amino function of
Lys53.[17] Due to the flexibility of this region of the kinase, this
hydrogen bond is not always visible in docking results. All the
predicted interaction sites are in line with binding modes of
imidazole-based inhibitors.[40] The acyl moiety interacts with
HR II. The predominant interactions between inhibitor and
HR II are hydrophobic (van der Waals) interactions, as a result
methylsulfanyl-5-pyridin-4-ylimidazol-1-yl]amide-based
p38a
MAPK inhibitors has been established. The substitution pattern
was optimized by variation of the acyl moiety at the N1 posi-
tion of the aminoimidazole core. The amino function was toler-
ated; acylation of the amino function can be used for optimi-
zation and leads to more potent p38a MAPK inhibitors compa-
rable
to
tetrasubstituted
2-acylaminopyridin-4-ylimida-
zoles.[21,25]
Experimental Section
General
The reagents and solvents used in this study are commercially
available and were used without further purification.
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S. A. Laufer et al.
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CH), 8.76–8.85 ppm (s, 1H, CH); 13C NMR ([D6]DMSO): d=13.8 (S-
Table 2. Test compounds and inhibition of p38a MAPK.
2
CH3), 109.1 (CH), 115.9 (d, J(C,F) =21.7 Hz, C3 and C5 4-F-Ph), 126.5
3
(d, J(C,F) =8.1 Hz, C2 and C6 4-F-Ph), 128.2 (Aryl), 129.5 (Aryl), 130.4
4
(d, J(C,F) =3.0 Hz, C1 4-F-Ph), 131.9, 133.2 (Aryl), 139.7 (Aryl), 145.8
1
(Aryl), 151.4 (N=CH-Ph), 161.7 ppm (d, J(C,F) =244.0 Hz, C4 4-F-Ph);
FTIR (ATR): n˜ =2933, 1599, 1557, 1496, 1452, 1415, 1405, 1342,
1308, 1292, 1206, 1172, 1156, 1101, 944, 841, 826, 756, 733,
690 cmꢀ1; MS (EI) m/z (%): 311 [M]+ (100), 297 (82), 175 (10), 163
(14), 148 (21), 121 (15).
Compd
R
IC50 [mm][a]
Ethyl-4-[1-benzylideneamino-4-(4-fluorophenyl)-2-methylthio-
1H-imidazol-5-yl]pyridine-1-4H-carboxylate (7): A solution of 6
(15.57 g, 50 mmol) in 1,2-dichloroethane (100 mL) and pyridine
(17 mL, 250 mmol) was cooled in an ice/salt bath. Ethyl chlorofor-
mate (15.71 mL, 16.5 mmol) was slowly added while keeping the
temperature <58C. The mixture was then allowed to warm to
room temperature while stirring. When HPLC reaction monitoring
indicated the presence of unreacted starting material, the mixture
was cooled to 0–58C, and a second portion of pyridine and ethyl
chloroformate was added. This procedure was continued until
starting material no longer remained. The reaction was then
poured into H2O (50 mL), and the aqueous phase was extracted
with CH2Cl2. The organic phases were washed with brine, dried
over Na2SO4, and the solvent was removed to obtain a brown solid
(20.8 g, 89.9%), which was used without further purification. HPLC:
tR =10.0 min (~90% purity); MS (ESI) m/z: 463 [M+1]+.
13a
0.071ꢁ0.06[b]
13b
0.029ꢁ0.01
Compd
R
IC50 [mm][a]
14a
0.107ꢁ0.01
14b
0.113ꢁ0.019[b]
N-Benzylidene-4-(4-fluorophenyl)-2-methylthio-5-(pyridin-4-yl)-
1H-imidazol-1-amine (8): Compound 7 (20.8 g, 45 mmol) was dis-
solved in mesitylene (120 mL); sulfur (1.6 g, 50 mmol) was added,
and the mixture was held at reflux for 3 h until the reaction
reached completion. The solvent was removed in vacuo, and Et2O
was added to the residue. A yellowish precipitate was filtered,
washed with Et2O, and dried in vacuo to afford compound 8 as a
brown powder (9.98 g, 51.4% over two steps). HPLC: tR =9.2 min
[a] Data reflect the mean ꢁSEM of three experiments except where
stated otherwise. [b] Results are from two experiments. SB 203580 IC50
=
0.034ꢁ0.003 mm (n=12).
Chemical analysis
1
(98.7% purity); mp: 169.98C; H NMR ([D6]DMSO): d=2.66 (s, 3H,
Melting points were determined on a Bꢁchi Melting Point B-545
apparatus and are thermodynamically corrected. 1H and 13C NMR
spectra were collected on a Bruker Avance Spectrospin AC200 in-
strument at 200 and 50 MHz, respectively. Chemical shifts (d) are
reported in ppm. MS data were recorded on a Finnigan Triple-
Stage Quadrupole (TSQ-70) instrument. HPLC data were deter-
mined on a HP 1090 instrument (ZORBAX Eclipseꢂ XDB-C8 column
[150ꢃ4.6 mm, dp=5 mm]. HPLC method: Eluent A: CH3OH (HPLC
grade), Eluent B: 0.01m KH2PO4 buffer (pH 2.3); 0 min 40:60,
8.0 min 85:15, 13.0 min 85:15, 14.0 min 40:60, 16.0 min 40:60; flow
rate: 1.0 mLminꢀ1. HPLC results are given as retention times (tR)
and relative purity (%). TLC analyses were performed on fluores-
cent silica gel 60 plates (Machery–Nagel, No. 818133), and spots
were visualized under UV illumination at l 254 and 366 nm. Com-
pounds 2, 3, and 5 were prepared according to published
data.[32–34]
S-CH3), 7.06–7.22 (m, 2H, 4-F-Ph), 7.28–7.66 (m, 9H, Ph, Pyr, 4-F-Ph),
7.70–7.83 (m, 2H, Pyr), 8.57 ppm (s, 1H, N=CH-Ph); 13C NMR
2
([D6]DMSO): d=15.0 (S-CH3), 115.4 (d, J(C,F) =21.6 Hz, C3 and C5 4-
3
F-Ph), 124.5 (Pyr), 124.9 (Aryl), 128.6 (Aryl), 128.9 (d, J(C,F) =8.3 Hz,
4
C2/C6 4-F-Ph), 129.2 (Aryl), 130.0 (d, J(C,F) =3.2 Hz, C1 4-F-Ph), 131.7
(Aryl), 132.8 (Aryl), 136.9 (Aryl), 137.2 (Aryl), 140.8 (Aryl), 150.0 (Pyr),
161.5 (d, 1J(C,F) =235.7 Hz, C4 4-F-Ph), 165.3 ppm (N=CH-Ph); FTIR
(ATR): n˜ =2924, 1600, 1574, 1541, 1510, 1442, 1408, 1286, 1218,
1155, 965, 839, 814, 758, 693 cmꢀ1; MS (EI) m/z (%): 388 [M]+ (58),
284 (100).
4-(4-Fluorophenyl)-2-methylthio-5-(pyridin-4-yl)-1H-imidazol-1-
amine (9): Compound 8 (5.256 g, 13.5 mmol) was suspended in 2-
methoxyethanol (20 mL). N2H4·H2O (98%, 4.3 mL, 135 mmol) was
added, and the mixture was held at reflux for 1 h. After reaction
completion (as monitored by HPLC), the mixture was taken up in
H2O (100 mL) and EtOAc (100 mL). The organic phase was washed
with H2O and brine, dried over Na2SO4, and the solvent was re-
moved in vacuo. The product was filtered, washed with Et2O, and
dried in vacuo to obtain compound 9 (2.069 g, 50.9%) as a yellow
powder. HPLC: tR =3.9 min (96% purity); mp: 152.38C; 1H NMR
([D6]DMSO): d=2.59 (s, 3H, S-CH3), 5.84 (s, 2H, NH2), 7.04–7.19 (m,
2H, 4-F-Ph), 7.34–7.47 (m, 4H, 4-F-Ph, Pyr), 8.54–8.66 ppm (m, 2H,
N-Benzylidene-4-(4-fluorophenyl)-2-methylthio-1H-imidazol-1-
amine (6): A mixture of 3 (11.81 g, 61.1 mmol), 5 (13.261 g,
61.1 mmol), NaHCO3 (15.4 g, 183 mmol), and CH3CN (70 mL) was
heated while stirring at 758C for 3 h. During this period the orange
solution turned into a suspension with a fawn precipitate. After
cooling to room temperature, the solids were filtered and washed
with cold CH3CN. The compound was suspended in H2O to dis-
solve the remaining inorganic salts. The insoluble solid was filtered
and dried in vacuo to give 6 as a fawn powder (15.43 g, 81%).
HPLC: tR =9.9 min (100% purity); mp: 144.5–1458C; 1H NMR
([D6]DMSO): d=2.65 (s, 3H, S-CH3), 7.15–7.33 (m, 2H, 4-F-Ph), 7.49–
7.60 (m, 3H, Ph), 7.75–7.91 (m, 4H, 4-F-Ph, C2/C6 Ph), 8.53 (s, 1H,
2
Pyr); 13C NMR ([D6]DMSO): d=14.0 (S-CH3), 115.6 (d, J(C,F) =21.5 Hz,
3
C3 and C5 4-F-Ph), 124.8 (Pyr), 128.5 (Aryl), 129.0 (d, J(C,F) =8.1 Hz,
4
C2 and C6 4-F-Ph), 131.2 (d, J(C,F) =3.1 Hz, C1 4-F-Ph), 136.3 (Aryl),
1
137.6 (Aryl), 147.0 (Aryl), 150.2 (Pyr), 161.5 ppm (d, J(C,F) =243.9 Hz,
C4 4-F-Ph); FTIR (ATR): n˜ =3341, 3108, 2934, 1597, 1537, 1510,
1480, 1441, 1410, 1367, 1317, 1291, 1220, 1160, 1132, 1093, 1000,
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N-Aminoimidazole-Based p38a MAP Kinase Inhibitors
968, 918, 834, 817 cmꢀ1; MS (ESI) m/z (%): 224 [M+1]+ (100), 175
(5); HRMS (EI) m/z Anal. calcd for C22H17FN4S: 388.115775, found:
388.11555.
S-CH3), 7.10–7.24 (m, 2H, 4-F-Ph), 7.26–7.35 (m, 2H), 7.41–7.71 (m,
5H), 7.74–7.87 (m, 2H), 8.51–8.68 (m, 2H, Pyr), 12.00 ppm (s, 1H,
2
NH); 13C NMR ([D6]DMSO): d=14.6 (S-CH3), 115.8 (d, J(C,F)
=
21.57 Hz, C3 and C5 4-F-Ph), 124.0 (Pyr), 127.8 (Benzoic acid), 127.9
(Aryl), 129.1 (3J(C,F) =8.2 Hz, C2 and C6 4-F-Ph), 129.3 (Benzoic acid),
129.6 (Aryl), 130.3 (Aryl), 130.3 (Aryl), 131.2 (Aryl), 133.3 (Benzoic
N-Acetyl-N-[4-(4-fluorophenyl)-2-methylsulfanyl-5-pyridin-4-yl-
1H-imidazol-1-yl]acetamide (10a): Variant a: Compound
9
4
(300 mg, 1.0 mmol) was dissolved in pyridine (8 mL) and cooled to
08C in an ice/salt bath. CH3COCl dissolved in CH2Cl2 (2.0 mL, 1m,
2.0 mmol) was slowly added, and the mixture was stirred for 1 h in
the ice bath. When the reaction was complete (HPLC monitoring)
the mixture was poured into ice and extracted with EtOAc. The or-
ganic layer was washed with H2O and brine, dried over Na2SO4,
and purified by flash chromatography (SiO2, EtOAc/PE 2:1) to give
a light-yellow powder (150 mg, 39%). Variant b: Compound 9
(300 mg, 1.0 mmol) was dissolved in (CH3CO)2O (0.5 mL), and 4-di-
methylaminopyridine (DMAP; 0.1 mg) was added. The mixture was
held at reflux for 2 h and poured into ice after cooling to room
temperature. The solution was neutralized with concentrated NH3.
Further purification was accomplished according to Variant a.
HPLC: tR =7.143 min (98.1% purity); 1H NMR ([D6]DMSO): d=2.26
(s, 6H, 2ꢃCOCH3), 2.69 (s, 3H, S-CH3), 7.10–7.26 (m, 4H, 4-F-Ph),
7.40–7.54 (m, 2H, Pyr), 8.60–8.74 ppm (m, 2H, Pyr); MS (FAB) m/z
(%): 385 [M+1]+ (100), 343 (64), 342 (30), 285 (18), 252 (20), 207
(20).
acid), 136.6 (d, J(C,F) =3.12 Hz, C1 4-F-Ph), 146.7 (Aryl), 150.6 (Pyr),
162.1 (d, 1J(C,F) =247.9 Hz, C-F), 165.9 ppm (CO); FTIR (ATR): n˜ =
3172, 2933, 1667 (C=O), 1601, 1514, 1484, 1437, 1411, 1484, 1309,
1279, 1223 (CꢀF), 1162, 1098, 1070, 965, 848, 821, 805, 712 cmꢀ1
;
MS (FAB) m/z (%): 405 [M+1]+ (82), 322 (53), 178 (51), 165 (100);
HRMS (EI) m/z Anal. calcd for C22H17FN4OS: 404.110685, found:
404.11150.
N-[4-(4-Fluorophenyl)-2-methylthio-5-(pyridin-4-yl)-1H-imidazol-
1-yl]furan-2-carboxamide (11c): Compound 11 c was prepared ac-
cording to General Procedure A using furan-2-carboxylic acid
(546 mg, 3.4 mmol) as carboxylic acid, 9 (360 mg, 1.2 mmol), and
CDI (546 mg, 3.4 mmol), and was purified by flash chromatography
(SiO2, EtOAc/PE 3:2) to give a light-yellow powder (82 mg, 20.4%).
HPLC: tR =5.82 min (99.0% purity); mp: 264.68C; 1H NMR
([D6]DMSO): d=2.61 (s, 3H, S-CH3), 6.67–6.74 (m, 1H, Furan), 7.10–
7.22 (m, 2H, C3 and C5 4-F-Ph), 7.24–7.36 (m, 3H, Pyr, Furan), 7.40–
7.52 (m, 2H, 4-F-Ph), 7.95–8.01 (m, 1H, Pyr), 11.97 ppm (s, 1H, NH);
2
13C NMR ([D6]DMSO): d=14.6 (S-CH3), 112.8 (Furan), 115.8 (d, J(C,F)
=
N-[4-(4-Fluorophenyl)-2-methylthio-5-(pyridin-4-yl)-1H-imidazol-
1-yl]acetamide (11a): Compound 10a (380 mg, 1.0 mmol) was dis-
solved in 5n HCl (2 mL) and stirred for 3.5 h at room temperature.
The mixture was then neutralized with concentrated NH3. The pre-
cipitate of 11 a was filtered, washed with H2O, and dried in vacuo
to give a white powder (195 mg, 57.0%). HPLC: tR =4.689 min
(98.2% purity); mp: 88.78C; 1H NMR ([D6]DMSO): d=1.92 (s, 3H,
COCH3), 2.60 (s, 3H, S-CH3), 7.07–7.21 (m, 2H, 4-F-Ph), 7.22–7.30 (m,
2H, Pyr), 7.36–7.50 (m, 2H, 4-F-Ph), 8.57–8.65 (m, 2H, Pyr),
11.56 ppm (s, 1H, NH); 13C NMR ([D6]DMSO): d=14.6 (S-CH3), 20.6
(COCH3), 115.8 (d, 2J(C,F) =21.7 Hz, C3 and C5 4-F-Ph), 123.9 (Pyr),
127.7 (Ar), 129.1 (d, 3J(C,F) =8.21 Hz, C2 and C6 4-F-Ph), 130.3 (d,
4J(C,F) =3.12 Hz, C1 4-F-Ph), 136.6 (Aryl), 136.7 (Aryl), 146.5 (Aryl),
150.4 (C2 and C6 Pyr), 161.8 (d, 1J(C,F) =161.8 Hz, C4 4-F-Ph),
168.0 ppm (CO); FTIR (ATR): n˜ =2931, 1690 (C=O), 1602, 1511, 1408,
1368, 1221, 1157, 839 cmꢀ1; MS (EI) m/z (%): 342 [M+1]+ (54), 300
(13), 284 (49), 123 (25), 105 (73), 77 (35), 41 (100); HRMS (EI) m/z
Anal. calcd for C17H15FN4OS: 342.095035, found: 342.10023.
21.6 Hz, C3 and C5 4-F-Ph), 117.1 (Furan), 124.1 (Pyr), 128.0 (Aryl),
3
129.1 (d, J(C,F) =8.2 Hz, C2/C6 4-F-Ph), 130.2 (4J(C,F) =3.2 Hz, C1 4-F-
Ph), 136.6 (Aryl), 136.7 (Aryl), 144.9 (Aryl), 146.8 (Aryl), 147.4
1
(Furan), 150.5 (Pyr), 156.7 (CO), 244.8 ppm (d, J(C,F) =244.8 Hz, C4 4-
F-Ph); FTIR (ATR): n˜ =1696 (C=O), 1602, 1586, 1510, 1410, 1310,
1283, 1226 (CꢀF), 1166, 1106, 1007, 965, 883, 836, 174, 163,
705 cmꢀ1; MS (EI) m/z (%): 394 [M]+ (38), 300 (6), 284 (27), 123
(100), 95 (84); HRMS (EI) m/z Anal. calcd for C20H15FN4O2S:
394.089946, found: 394.08784.
3-Fluoro-N-[4-(4-fluorophenyl)-2-methylthio-5-(pyridin-4-yl)-1H-
imidazol-1-yl]-4-methylbenzamide (11d): Compound 11 d was
prepared according to General Procedure A using 3-fluoro-4-
methyl benzoic acid (300 mg, 1.0 mmol) as carboxylic acid, 9
(100 mg, 1.0 mmol), and CDI (535 mg, 3.3 mmol), and the mixture
was stirred at 1208C for 20 h to give a light-yellow powder
(185 mg, 36.2%). HPLC: tR =7.536 min (99.6% purity); mp: 245.08C;
1H NMR (CH3OD): d=2.29 (s, 3H, CH3), 2.64 (s, S-CH3), 7.08–7.23 (m,
2H, 4-F-Ph), 7.25–7.34 (m, 2H, 3-F-4-CH3-BA), 7.40–7.65 (m, 5H, 4-F-
General Procedure A: Under N2 atmosphere N,N’-carbonyldiimida-
zole (CDI; 535 mg, 3.3 mmol) was added to a solution of the ap-
propriate carboxylic acid (100 mg, 3.0 mmol) in dry 1-methyl-2-pyr-
rolidinone (3 mL) in a three-neck flask and stirred at room tempera-
ture until gas formation ceased. Then compound 9 (1.0 mmol) was
added under N2 atmosphere and stirred at 1208C until no more
educts remained (as monitored by HPLC). After cooling to room
temperature, the mixture was taken up in EtOAc (30 mL) and half-
saturated NaHCO3 (30 mL). The aqueous phase was extracted once
with EtOAc, and the combined organic layers were washed with
H2O and brine, dried over anhydrous Na2SO4, and the solvent was
removed in vacuo. The products were purified by flash chromatog-
raphy if necessary.
Ph, Pyr, 3-F-4-CH3-BA), 8.47–8.72 (m, 2H, Pyr), 12.01 ppm (s, 1H,
2
NH); 13C NMR (CH3OD): d=14.6 (CH3), 14.7 (CH3), 114.2 (d, J(C,F)
=
2
24.2 Hz, C2 3-F-4-CH3-BA), 115.8 (d, J(C,F) =21.6 Hz, C3 and C5 4-F-
Ph), 123.8 (d, 4J(C,F) =3.2 Hz, C6 3-F-4-CH3-BA), 124.0 (Pyr), 127.9
3
(Aryl), 129.1 (d, J(C,F) =8.3 Hz, C2 and C6 4-F-Ph), 130.3 (Aryl), 130.3
3
(d, 2J(C,F) =13.1 Hz, C4 3-F-4-CH3-BA), 130.6 (Aryl), 132.6 (d, J(C,F)
=
5.1 Hz, C5 3-F-4-CH3-BA), 136.5 (Aryl), 136.7 (Aryl), 146.7 (Aryl),
3
150.8 (Aryl), 160.7 (d, 1J(C,F) =245.2 Hz, C-F), 161.8 (d, J(C,F)
=
244.9 Hz, C-F), 164.5 ppm (CO); FTIR (ATR): n˜ =3212, 1665 (C=O),
1602, 1576, 1515, 1493, 1438, 1412, 1384, 1312, 1288, 1273, 1216
(CꢀF), 1196, 1164, 1136, 1080, 993, 967, 897, 848, 830, 817 cmꢀ1
;
MS (EI) m/z (%): 436.0 [M]+ (27), 284 (9), 137 (100), 109 (36); HRMS
(EI) m/z Anal. calcd for C23H18F2N4OS: 436.11691, found: 436.11626.
N-[4-(4-Fluorophenyl)-2-methylthio-5-(pyridin-4-yl)-1H-imidazol-
1-yl]benzamide (11b): Compound 11 b was prepared according to
General Procedure A using benzoic acid (366 mg, 3.0 mmol) as car-
boxylic acid, 9 (100 mg, 1.0 mmol), and CDI (535 mg, 3.3 mmol),
and was purified by flash chromatography (SiO2, EtOAc/PE 4:1) to
give a light-yellow powder (125 mg, 37.5%). HPLC: tR =6.25 min
2-(4-Fluorophenyl)-N-[4-(4-fluorophenyl)-2-methylthio-5-(pyri-
din-4-yl)-1H-imidazol-1-yl]acetamide (11e): Compound 11 e was
prepared according to General Procedure A using (4-fluorophenyl)-
acetic acid (120 mg, 0.4 mmol) as carboxylic acid, 9 (120 mg,
40 mmol), and CDI (214 mg, 1.3 mmol), and the mixture was stirred
at 1208C for 3 h and was purified by flash chromatography (SiO2,
EtOAc/PE 1:1) to give a yellow powder (80 mg, 45.8%). HPLC: tR =
1
(98.9% purity); mp: 268.88C; H NMR ([D6]DMSO): d=2.63 (s, 3H,
ChemMedChem 2010, 5, 1134 – 1142
ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemmedchem.org
1139

S. A. Laufer et al.
MED
1
6.94 min (99% purity); mp: 208.18C; H NMR (CH3OD): d=2.52 (s,
3H, S-CH3), 3.47 (s, 2H, CH2), 6.84–6.99 (m, 4H, 2ꢃC3/C5 4-F-Ph),
7.02–7.14 (m, 4H, C2/C6 4-F-Ph), 7.27–7.40 (m, 2H, Pyr), 8.23 ppm
(2H, Pyr); 13C NMR (CH3OD): d=13.9 (S-CH3), 39.1 (CH2), 114.9 (d,
2J(C,F) =21.7 Hz, 2ꢃC3 and C5 4-F-Ph), 124.2 (Pyr), 127.3 (Aryl), 129.2
(s, 1H, Pyr), 11.85 ppm (s, 1H, NH); 13C NMR ([D6]DMSO): d=14.7
(S-CH3), 66.3 (CH2), 115.0 (Ph), 115.8 (d, 2J(C,F) =21.7 Hz, C3/C5 4-F-
3
Ph), 121.9 (Ph), 124.0 (Pyr), 127.8 (Aryl), 129.1 (d, J(C,F) =8.3 Hz, C2
4
and C6 4-F-Ph), 129.8 (C3 and C5 Ph), 130.3 (d, J(C,F) =3.1 Hz, C4 4-
F-Ph), 136.4 (Aryl), 136.6 (Aryl), 146.4 (Aryl), 150.5 (Pyr), 157.7 (Aryl),
161.8 (d, 1J(C,F) =244.9 Hz, C4 4-F-Ph), 168.0 ppm (CO); FTIR (ATR):
n˜ =3154, 1699 (C=O), 1600, 1509, 1490, 1250, 1442, 1409, 1310,
4
4
(d, J(C,F) =8.2 Hz, C4 4-F-Ph), 29.6 (Aryl), 130.4 (d, J(C,F) =8.1 Hz, C4
4-F-Ph), 137.3 (Aryl), 137.6 (q, Aryl), 147.1 (q, Aryl), 149.0 (C2 and
1
1
C6 Pyr), 162.0 (d, J(C,F) =244.3 Hz, C1 4-F-Ph), 162.4 (d, J(C,F) =246.1,
C1 4-F-Ph), 170.6 ppm (CO); FTIR (ATR): n˜ =3195, 3007, 1683 (C=O),
1603, 1507, 1442, 1416, 1216, 1156, 844, 818, 789 cmꢀ1; MS (EI) m/z
(%): 436 [M]+ (16), 284 (20), 109 (26), 68 (100); HRMS (EI) m/z Anal.
calcd for C23H18F2N4OS: 436.11691, found: 436.11568.
1245, 1216, 1173, 1156, 1082, 1066, 846, 809, 828, 758, 693 cmꢀ1
;
MS (EI) m/z (%): 434 [M+1]+ (100), 284 (58), 252 (29), 107 (18), 77
(27); HRMS (EI) m/z Anal. calcd for C23H19FN4O2S: 434.1212, found:
434.1176.
N-[4-(4-Fluorophenyl)-2-methylthio-5-(pyridin-4-yl)-1H-imidazol-
1-yl]benzofuran-2-carboxamide (11i): Compound 11 i was pre-
pared according to General Procedure A using benzofuran-2-car-
boxylic acid (486 mg, 3.0 mmol) as carboxylic acid, 9 (100 mg,
1.0 mmol), and CDI (535 mg, 3.3 mmol). The mixture was stirred at
1208C for 21 h and was purified by flash chromatography (SiO2,
EtOAc/PE 1:1) to give a fawn powder (193 mg, 43.4%). HPLC: tR =
2-(2-Chlorophenyl)-N-[4-(4-fluorophenyl)-2-methylthio-5-(pyri-
din-4-yl)-1H-imidazol-1-yl]acetamide (11 f): Compound 11 f was
prepared according to General Procedure A using (2-chlorophenyl)-
acetic acid (535 mg, 3.3 mmol) as carboxylic acid, 9 (100 mg,
1.0 mmol), and CDI (535 mg, 3.3 mmol). The reaction was stirred at
1208C for 6 h. The residue was treated with diisopropyl ether to
give a fawn powder (368 mg, 81%). HPLC: tR =6.509 min (98.7%
1
7.614 min (98% purity); mp: 266.28C; H NMR ([D6]DMSO): d=2.64
1
purity), mp: 223.88C; H NMR (CH3OD): d=2.55 (s, 3H, S-CH3), 3.67
(s, 3H, S-CH3), 7.09–7.25 (m, 2H, 4-F-Ph), 7.26–7.62 (m, 6H), 7.65–
7.88 (m, 3H), 8.52–8.64 (m, 2H, Pyr), 12.36 ppm (s, 1H, NH);
13C NMR ([D6]DMSO): d=14.7 (S-CH3), 112.4 (BF), 113.1 (BF), 115.8
(s, 2H, CH2), 6.85–7.01 (m, 2H, C3/C5 4-F-Ph), 7.06–7.42 (m, 6H, 2-
Cl-Ph, Pyr, 4-F-Ph), 8.32–8.46 ppm (m, 2H, C2/C6 Pyr); 13C NMR
(CH3OD): d=15.7 (S-CH3), 39.3 (CH2), 116.6 (d, 2J(C,F) =21.9 Hz, C3
and C5 4-F-Ph), 126.1 (Pyr), 128.2 (Aryl), 128.5 (2-Cl-Ph), 129.1 (Aryl),
129.9 (Aryl), 130.4 (2-Cl-Ph), 130.5 (2-Cl-Ph), 130.7 (2-Cl-Ph), 130.9
2
(d, J(C,F) =21.7 Hz, C3 and C5 4-F-Ph), 123.7 (BF), 124.0 (Pyr), 124.6
3
(BF), 126.9 (Aryl), 127.9 (Aryl), 128.4 (BF), 129.2 (d, J(C,F) =8.2 Hz, C2
and C6 4-F-Ph), 130.2 (d, 4J(C,F) =3.1 Hz, C1 4-F-Ph), 136.5 (Aryl),
136.8 (Aryl), 145.9 (Aryl), 146.7 (Aryl), 150.6 (Pyr), 155.0 (Aryl), 157.5
(Aryl), 161.9 ppm (d, 1J(C,F) =244.9 Hz, C1 4-F-Ph); FTIR (ATR): n˜ =
2931, 1690 (CONH), 1598, 1578, 1509, 1484, 1411, 1375, 1287, 1214,
1169, 1146, 1135, 1063, 1103, 835, 805, 747, 718 cmꢀ1; MS (EI) m/z
(%): 444 [M]+ (76), 284 (32), 145 (100), 89 (18); HRMS (EI) m/z Anal.
calcd for C24H17FN4O2S: 444.1056, found: 444.1032.
3
(d, J(C,F) =8.1 Hz, C2 and C6 4-F-Ph), 133.3 (Aryl), 139.2 (Aryl), 148.9
1
(Aryl), 150.9 (Pyr), 164.1 (d, J(C,F) =246.6 Hz, C4 4-F-Ph), 171.3 ppm
(CO); FTIR (ATR): n˜ =3244, 1687, 1602, 1510, 1445, 1409, 1351,
1307, 1222, 1156, 1130, 1094, 1055, 961, 842, 830, 819, 807, 773,
751, 743, 711, 686 cmꢀ1; MS (EI) m/z (%): 452 [M]+ (62), 284 (77),
252 (32), 181 (24), 125 (100); HRMS (ESI) m/z Anal. calcd for
C23H18ClFN4OS: 452.08736; found, 452.08539.
2-(2-Chlorophenyl)-N-[3-(4-fluorophenyl)-1-methyl-4-(pyridin-4-
yl)-1H-pyrazol-5-yl]acetamide (13a): According to General Proce-
dure A compound 13a was prepared using (2-chlorophenyl)acetic
acid (240 mg, 1.4 mmol), CDI (351 mg, 1.6 mmol), and 3-(4-fluoro-
N-[4-(4-fluorophenyl)-2-methylthio-5-(pyridin-4-yl)-1H-imidazol-
1-yl]-2-phenylpropanamide (11g): Compound 11 g was prepared
according to General Procedure A using 2-phenylpropanoic acid
(608 mg, 4.1 mmol) as carboxylic acid, 9 (405 mg, 1.35 mmol), and
CDI (722 mg, 4.5 mmol). The reaction was stirred at 1208C for 5 h.
It was purified by flash chromatography (SiO2, EtOAc/PE 3:2) to
give a white powder (341 mg, 58.4%). HPLC: tR =6.580 min (99.9%
phenyl)-1-methyl-4-(pyridin-4-yl)-1H-pyrazol-5-amine
(1.0 mmol).
The product was purified by flash chromatography (SiO2, EtOAc/PE
7:3) to give a white powder. HPLC: tR =5.427 min (98.0% purity),
1
mp: 216.88C; H NMR ([D6]DMSO): d=3.72 (s, 3H, CH3), 3.89 (s, 2H,
1
purity); mp: 189.78C; H NMR ([D6]DMSO): d=1.34–1.43 (d, 3H, J=
CH2), 7.07–7.50 (m, 10H, 2-Cl-Ph, 4-F-Ph, Pyr), 8.40–8.55 (m, 2H,
6.94 Hz, CH3), 2.50 (s, 3H, S-CH3), 3.56–3.82 (m, 1H, CH), 6.90–7.59
(m, 9H, 4-F-Ph, Ph), 8.16–8.36 (m, 1H, Pyr), 8.54–8.71 (m, 1H, Pyr),
11.53 ppm (s, 1H, NH); 13C NMR ([D6]DMSO): d=14.1 (S-CH3), 18.0
(CH3), 43.1 (CH), 115.4 (d, 2J(C,F) =21.62 Hz, C3/C5 4-F-Ph), 123.4
Pyr), 10.23 ppm (s, 1H, NH); 13C NMR ([D6]DMSO): d=35.7 (CH3),
2
39.7 (CH2), 112.0 (Pyrazole), 115.4 (d, J(C,F) =21.6 Hz, C3 and C5 4-F-
Ph), 123.7 (Pyr), 127.1 (C5 2-Cl-Ph), 128.9 (2-Cl-Ph), 129.0 (2-Cl-Ph),
4
2
129.3 (d, J(C,F) =3.1 Hz, C1 4-F-Ph), 129.7 (d, J(C,F) =8.26 Hz, C4 4-F-
3
(Pyr), 127.3 (Ph), 127.5 (Ph), 128.4 (Ph), 128.7 (d, J(C,F) =8.16 Hz, C2
Ph), 132.4 (2-Cl-Ph), 133.2 (Aryl), 133.6 (Aryl), 135.2 (Aryl), 139.9
1
and C6 4-F-Ph), 129.9 (d, 4J(C,F) =3.02 Hz, C4 4-F-Ph), 138.7 (Aryl),
136.0 (Aryl), 136.3 (Aryl), 139.8 (Aryl), 146.1 (Aryl), 149.7 (Pyr), 161.4
(d, 1J(C,F) =245.14 Hz, C4 4-F-Ph), 172.5 ppm (CO); FTIR (ATR): n˜ =
3239, 1683, 1603, 1511, 1491, 1447, 1416, 1373, 1308, 1215, 1172,
1160, 1097, 993, 964, 943, 850, 816, 766, 748, 729, 697 cmꢀ1; MS
(EI) m/z (%): 432 [M]+ (26), 284 (20), 105 (100); HRMS (ESI) m/z
Anal. calcd for C24H21FN4OS: 432.141986, found: 432.14342.
(Pyr), 145.9 (Pyr), 149.7 (Pyr), 161.8 (d, J(C,F) =245.1 Hz, C4 4-F-Ph),
169.9 ppm (CO); FTIR (ATR): n˜ =2944, 1693 (CONH), 1673, 1604,
1571, 1507, 1476, 1446, 1411, 1354, 1312, 1225 (CꢀF), 1156, 1119,
1095, 1054, 1004, 986, 841, 790, 750, 741, 685 cmꢀ1; MS (EI) m/z
(%): 421 [M+1]+ (100), 269 (16); HRMS (EI) m/z Anal. calcd for
C23H18ClFN4O: 420.115289, found: 420.11494.
2-(4-Fluorophenyl)-N-[3-(4-fluorophenyl)-1-methyl-4-(pyridin-4-
yl)-1H-pyrazol-5-yl]acetamide (13b): According to General Proce-
dure A compound 13b was prepared using (4-fluorophenyl)acetic
acid (263 mg, 1.7 mmol), CDI (300 mg, 1.9 mmol), and 3-(4-fluoro-
N-[4-(4-Fluorophenyl)-2-methylthio-5-(pyridin-4-yl)-1H-imidazol-
1-yl]-2-phenoxyacetamide (11h): Compound 11 c was prepared
according to General Procedure A using phenoxyacetic acid
(457 mg, 3.0 mmol) as carboxylic acid, 9 (100 mg, 1.0 mmol), and
CDI (535 mg, 3.3 mmol). The mixture was stirred at 1208C for 6.5 h
and was purified by flash chromatography (SiO2, EtOAc/PE 1:1) to
give a fawn powder (185 mg, 42.6%). HPLC: tR =7.166 min (100%
purity); mp: 229.48C; 1H NMR ([D6]DMSO): d=2.61 (s, 3H, S-CH3),
4.64–4.74 (s, 2H, CH2), 6.78–6.92 (m, 2H, Ph), 6.92–7.05 (m, 1H, Ph),
7.07–7.34 (m, 6H, Aryl), 7.38–7.50 (m, 2H, C2/C6 4-F-Ph), 8.51–8.74
phenyl)-1-methyl-4-(pyridin-4-yl)-1H-pyrazol-5-amine
(1.0 mmol).
The product was purified by flash chromatography (SiO2, EtOAc/PE
1:1) to give a white powder (56 mg, 24.3%). HPLC: tR =6.194 min
1
(100% purity); mp: 216.58C; H NMR ([D6]DMSO): d=3.59–3.71 (m,
5H, CH3, CH2), 6.97–7.06 (m, 2H, 4-F-Ph), 7.07 ꢀ7.25 (m, 4H, 4-F-Ph,
Pyr), 7.25–7.42 (m, 4H, 4-F-Ph), 8.32–8.50 (m, 2H, Pyr), 10.17 ppm
(s, 1H, NH); 13C NMR ([D6]DMSO): d=35.6 (S-CH3), 41.1 (CH2), 111.9
1140
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ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 2010, 5, 1134 – 1142

N-Aminoimidazole-Based p38a MAP Kinase Inhibitors
2
2
(Pyrazole), 114.2 (d, J(C,F) =21.62 Hz, C3/C5 4-F-Ph), 115.5 (d, J(C,F)
=
(212 mg, 50.4%). HPLC: tR =6.25 min (98.9% purity); mp: 223.98C;
1H NMR ([D6]DMSO): d=2.62 (s, 3H, S-CH3), 6.99–7.22 (m, 4H, 4-F-
Ph), 7.28–7.55 (m, 6H, 4-F-Ph, Pyr), 8.53–8.70 (m, 2H, Pyr), 9.39 (s,
NH), 9.68 ppm (s, NH); 13C NMR ([D6]DMSO): d=14.6 (S-CH3), 115.6
(d, 2J(C,F) =22.3 Hz, C3 and C5 4-F-Ph), 115.7 (d, 2J(C,F) =21.1 Hz, C3
4
20.61 Hz, C3 and C5 4-F-Ph), 123.6 (Pyr), 129.3 (d, J(C,F) =3.14, C1 4-
F-Ph), 129.8 (d, 3J(C,F) =8.3 Hz, C2 and C6 4-F-Ph), 131.0 (d, J(C,F)
3
=
8.1 Hz, C2 and C6 4-F-Ph), 131.3 (d, 4J(C,F) =3.14,C1 4-F-Ph), 135.0
(Pyrazole), 139.9 (C4 Pyr), 145.9 (Pyrazole), 149.7 (Pyr), 161.3 (d,
1J(C,F) =242.9 Hz, C2 and C6 4-F-Ph), 161.8 (d, 1J(C,F) =232.7 Hz, C2
and C6 4-F-Ph), 171.0 ppm (CO); FTIR (ATR): n˜ =3230, 1667 (C=O),
1600, 1569, 1546, 1512, 1449, 1416, 1357, 1312, 1214, 1198, 1161,
1120, 1099, 1017, 985, 845, 825, 808, 785, 715, 724, 667 cmꢀ1; MS
(EI) m/z (%): 404 [M]+ (18), 268 (87), 109 (100); HRMS (EI) m/z Anal.
calcd for C23H18F2N4O: 404.14778 found: 404.11484.
3
and C5 4-F-Ph), 121.1 (Pyr), 124.4, 129.0 (d, J(C,F) =8.2 Hz, C2 and
C6 4-F-Ph), 130.6 (d, 4J(C,F) =C1 4-F-Ph), 135.5 (Aryl), 136.3 (Aryl),
1
137.0 (Aryl), 147.5 (Aryl), 150.4 (Pyr), 153.6 (CO), 158.1 (d, J(C,F)
=
239.6 Hz, C4 4-F-Ph), 161.7 ppm (d, 1J(C,F) =244.6 Hz, C4 4-F-Ph);
FTIR (ATR): n˜ =3191, 1680 (C=O), 1603, 1569, 1509, 1410, 1310,
1218 (CꢀF), 1158, 1098, 1066, 836 cmꢀ1; MS (EI) m/z (%): 437 [M]+
(37), 284 (34), 123 (100), 95 (51); HRMS (EI) m/z Anal. calcd for
C22H17F2N5OS: 437.112155, found: 437.11324.
N-[3-(4-Fluorophenyl)-4-(pyridin-4-yl)isoxazol-5-yl]-2-phenylpro-
panamide (14a): Compound 14a was prepared according to Gen-
eral Procedure A using 2-phenylpropanoic acid (0.41 mL,
3.0 mmol), CDI (535 mg, 3.3 mmol), and 3-(4-fluorophenyl)-4-(pyri-
din-4-yl)isoxazol-5-amine (255 mg, 1.0 mmol), and the reaction was
stirred at 1208C for 6 h. Purification was carried out by flash chro-
matography (SiO2, EtOAc/PE 1:1) to give a white powder (191 mg,
Acknowledgements
The authors thank the Federal Ministry of Education and Re-
search (Germany) for generous support of this work. The authors
are also grateful to M. Goettert and K. Bauer for biological test-
ing.
1
49.3%). HPLC: tR =6.462 min (99.0% purity); mp: 299.08C; H NMR
([D6]DMSO): d=1.24–1.45 (d, 3H, J=6.69 Hz, CH3), 3.78–2.97 (d,
1H, J=6.69 Hz, CH), 3.83–6.99 (m, 2H, C3 and C5 4-F-Ph), 7.18–
7.54 (m, 9H), 8.31–8.50 (m, 2H, Pyr), 10.99 ppm (s, 1H, NH);
13C NMR ([D6]DMSO): d=18.0 (CH3), 45.1 (CH), 106.6 (Isoxazole),
116.0 (d, J(C,F) =21.87 Hz, C3 and C5 4-F-Ph), 123.4 (Pyr), 124.6 (d,
4J(C,F) =3.3 Hz, C4 4-F-Ph), 127.1 (C4 Ph), 127.4 (Ph), 128.5 (Ph), 130.7
Keywords: cytokines
·
inhibitors
· p38 MAP kinase ·
2
pyridinylimidazoles
3
(d, J(C,F) =8.7 Hz, C2 and C6 4-F-Ph), 136.7 (Aryl), 140.4 (Aryl), 149.6
(Pyr), 159.4 (Aryl), 161.1 (Aryl), 162.9 (d, J(C,F) =241.4 Hz, C4 4-F-Ph),
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1
172.4 ppm (CO); FTIR (ATR): n˜ =3278, 2974, 1691, 1633, 1600, 1548,
1527, 1506, 1456, 1432, 1412, 1373, 1328, 1232, 1160, 1123, 1098,
1030, 994, 889, 851, 830, 819, 790, 758, 730, 698, 687 cmꢀ1; MS (EI)
m/z (%): 388 [M+1]+ (3), 266 (9), 255 (66), 168 (17), 132 (42), 105
(100); HRMS (ESI) m/z Anal. calcd for C23H18FN3O2 387.13633,
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F-Ph, Pyr), 8.42–8.53 (m, 2H, Pyr), 11.11 ppm (s, 1H, NH); 13C NMR
2
([D6]DMSO): d=41.1 (CH2), 106.5 (Isoxazole), 115.1 (d, J(C,F)
=
2
21.27 Hz, C3 and C5 4-F-Ph), 116.0 (d, J(C,F) =22.02 Hz, C3 and C5 4-
F-Ph), 123.7 (Pyr), 124.5 (C1 4-F-Ph), 124.6 (C1 4-F-Ph), 130.7 (d,
3
3J(C,F) =8.92 Hz, C2 and C6 4-F-Ph), 131.1 (d, J(C,F) =8.11 Hz, C2 and
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1
zole), 161.2 (d, 1J(C,F) =246.9 Hz, C4 4-F-Ph), 163.1 (d, J(C,F)
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246.9 Hz, C4 4-F-Ph), 169.4 ppm (CO); FTIR (ATR): n˜ =3072, 2822,
1714, 1623, 1603, 1589, 1545, 1509, 1463, 1430, 1416, 1323, 1218,
1171, 1149, 1109, 1092, 1073, 1035, 1002, 957, 917, 862, 818, 795,
770, 745, 697 cmꢀ1; MS (EI) m/z (%): 388 [M+1]+ (3), 266 (9), 255
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Received: March 21, 2010
Revised: March 31, 2010
Published online on May 14, 2010
1142
www.chemmedchem.org
ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 2010, 5, 1134 – 1142