Synthesis and biological evaluation of phenyl piperidine derivatives as CCR2 antagonists

Article abstract of DOI:10.1016/j.bmcl.2007.07.065

A series of phenyl piperidine derivatives possessing potent and selective CCR2 antagonist activity is reported. Structure-activity relationship (SAR) studies have established that incorporation of a second ring system adjacent to the aryl piperidine plays an important role in determining the CCR2 potency. Both a second piperidine ring and a 1,3-substituted cyclopentylamine have been probed as linkers. For the cyclopentylamine series, the 1S,3R-configuration exhibits much higher affinity for hCCR2 than the 1R,3S-configuration. Compound 3g shows good selectivity over CCR1, CCR3, 5-HT and has an excellent P450 profile.

Full text of DOI:10.1016/j.bmcl.2007.07.065

Bioorganic & Medicinal Chemistry Letters 17 (2007) 5964–5968
Synthesis and biological evaluation of phenyl piperidine
derivatives as CCR2 antagonists
Mingde Xia,* Cuifen Hou, Scott Pollack, James Brackley, Duane DeMong, Meng Pan,
Monica Singer, Michele Matheis, Gil Olini, Druie Cavender and Michael Wachter
Drug Discovery, Johnson & Johnson Pharmaceutical Research and Development, L.L.C., 8 Clarke Drive, Cranbury, NJ 08512, USA
Received 23 May 2007; revised 17 July 2007; accepted 19 July 2007
Available online 21 August 2007
Abstract—A series of phenyl piperidine derivatives possessing potent and selective CCR2 antagonist activity is reported. Structure–
activity relationship (SAR) studies have established that incorporation of a second ring system adjacent to the aryl piperidine plays
an important role in determining the CCR2 potency. Both a second piperidine ring and a 1,3-substituted cyclopentylamine have
been probed as linkers. For the cyclopentylamine series, the 1S,3R-configuration exhibits much higher affinity for hCCR2 than
the 1R,3S-configuration. Compound 3g shows good selectivity over CCR1, CCR3, 5-HT and has an excellent P450 profile.
ꢀ 2007 Elsevier Ltd. All rights reserved.
O
O
Chemokines, a large sub-family of chemoattractant
cytokines, are small secreted proteins that attract and
activate immune and non-immune cells.1,2 They are gen-
erally classified into four sub-families: CXC, CC, CX3C
and C chemokines, based on the configuration of con-
served cysteine residues.3 Monocyte chemoattractant
protein-1 (MCP-1) is a CC chemokine and a potent che-
moattractant or activator for monocytes. It is postulated
to be primarily responsible for the selective recruitment
of leukocytes from the circulation to the site of inflam-
mation by binding to its seven transmembrane GPCR
(CCR2) on the surface of monocytes and macro-
phages.4,5 The evidence in favor of CCR2 and MCP-1
having dominant roles in monocyte chemotaxis and
chronic inflammation was provided by CCR2 and
MCP-1 knockout mice.6,7 It has been recognized that
CCR2 antagonists are potential therapeutic agents for
various pathological conditions, such as psoriasis, uve-
itis, rheumatoid arthritis, multiple sclerosis, asthma,
obesity, Chronic Obstructive Pulmonary Disease
(COPD) and Crohn’s Disease.8–16
R
N
Cl
Cl
N
H
1
HN
N
n
N
H
R1
R2
2
R2
R1
N
N
n
N
O
3
R1
R2
O
NH
Over the past few years, several series of CCR2 antago-
nists have been reported.17–24 Among them, Forbes et al.
disclosed indolopiperidine derivatives22 (1, Fig. 1) that
4
Figure 1. Evolution of Forbes indolopiperidine open chain derivatives
(1) to closed ring analogs (3 and 4).
Keywords: CCR2 antagonist; MCP-1.
*
were not progressed due to unwanted 5-HT receptor
affinities. Based on this structure, we made a series of
Corresponding author. Tel.: +1 609 409 3485; fax: +1 609 655
6930; e-mail: mxia@prdus.jnj.com
0960-894X/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2007.07.065

M. Xia et al. / Bioorg. Med. Chem. Lett. 17 (2007) 5964–5968
5965
modifications including changing the indole ring to a
substituted phenyl, optimizing the linker length between
the two nitrogens, and switching from the pentylamine
chain to more rigid ring systems such as cyclopentyl-
amine or piperidine.
ing affinities of the phenyl-piperidine analogs we be-
lieved these were viable lead structures.
It was reasoned that increasing the rigidity of the linking
sub-unit would hold the distance between the two nitro-
gens more constant and that decreasing the number of
rotatable bonds might improve potency. In an effort to
increase binding affinity of the phenyl-piperidine ana-
logs the linking carbon chain was tied back to the amide
nitrogen to form a ring.
Initial SAR studies of the straight-chain series indicated
that 4-(4-methoxyphenyl) piperidine and 4-(4-chlor-
ophenyl) piperidine were good functional groups, with
the optimized linker length between the nitrogens being
four or five-carbons. Table 1 lists the CCR2 binding
affinities for four-carbon and five-carbon analogs,
respectively.25 Binding affinity was diminished with link-
ers containing less than four carbons or greater than five
carbons.
We were delighted to see that replacing the pentylamine
linker with piperidin-4-yl methyl gave compounds with
improved binding affinity. Table 2 lists the IC50 data
for structure 3 containing a second piperidine ring as a
linker. The compound with piperidin-4-yl methyl (3g)
had higher CCR2 binding affinity than the compound
with piperidin-4-yl ethyl (3n). For R1, para-substituents
gave better potency than ortho- or meta-substituents (3c
vs 3a and 3b). For R2, dichloro was favored over dime-
thoxy (3g vs 3j).
The affinity of these analogs generally was in the low sin-
gle-digit micromolar range. It was reasoned that the
phenyl-piperidine analogs would not possess the un-
wanted 5-HT activity that plagued the indolopiperidine
analog, structure 1. Based on this premise and the bind-
Table 1. Open chain, four-carbon linkage analogs (structure 2, Fig. 1)
O
R2
R1
N
H
N
n
Compound
R1
R2
n
CCR2B binding IC50 (lM)
2a
2b
2c
2d
2e
2f
4-Chloro
4-Chloro
4-Fluoro
3,4-Dichloro
3,5-Difluoro
1
1
1
1
1
1
1
1
2
2
2
2
2
3.1
2.9
4.5
1.9
2.3
2.6
3.8
3.4
1.8
1.2
2.1
1.5
12.6
4-Chloro
4-Chloro
3,4,5-Trifluoro
4-Fluoro
4-Methoxy
4-Methoxy
4-Methoxy
4-Methoxy
4-Chloro
3,4-Dichloro
3,5-Difluoro
3,4,5-Trifluoro
4-Fluoro
2g
2h
2i
2j
4-Chloro
3,4-Dichloro
4-Fluoro
2k
2l
4-Methoxy
4-Methoxy
4-Hydroxy
3,4-Dichloro
3,4-Dichloro
2m
Table 2. Analogs containing a second piperidine ring of structure 3 from Figure 1
R2
R1
N
n
N
O
Compound
R1
n
R2
CCR2B binding IC50 (lM)
3a
3b
3c
3d
3e
3f
2-Methoxy
3-Methoxy
4-Methoxy
4-Dimethylamino
4-Hydroxy
4-Methyl
1
1
1
1
1
1
1
1
1
1
1
1
2
3,4-Dichloro
3,4-Dichloro
3,4-Dichloro
3,4-Dichloro
3,4-Dichloro
3,4-Dichloro
3,4-Dichloro
3,4-Difluoro
11.1
4.0
0.32
0.95
0.51
2.2
3g
3h
3j
4-Chloro
4-Chloro
0.30
2.0
4-Chloro
4-Chloro
3,4-Dimethoxy
3-Trifluoromethyl
4-Bromo
5.9
1.4
3k
3l
4-Chloro
4-Chloro
4-Chloro
5.2
17% at 25 lM
2.9
3m
3n
2-Fluoro-4-bromo
3,4-Dichloro

5966
M. Xia et al. / Bioorg. Med. Chem. Lett. 17 (2007) 5964–5968
Table 2 shows that the piperidine–methylene–piperidine
compounds 3c, 3e, and 3g possess binding affinities in
the sub-micromolar range. The 4-chlorophenyl analog
3g was chosen for further biological evaluation. The
results are shown in Table 3 below.
chloride, then reacted with a substituted phenyl piperi-
dine to give compound 3.
The effect of replacing the second piperidine ring with a
5-membered carbocyle was also investigated. To this end
cyclopentylamine analogs (4 in Fig. 1) were synthesized
using a similar synthetic route as Scheme 1. Table 4 lists
binding data for a select group of these analogs.
It may be seen from the results shown in Table 3
that compound 3g does not show 5-HT inhibition
at 1 lM as compared with structure 1 which does
have 5-HT activity. Furthermore compound 3g is
selective against CCR1 and CCR3 and possesses
acceptable oral bioavailability of 19%. This com-
pound was tested for in vivo efficacy. In the thiogly-
collate-induced peritonitis model in mice, compound
3g inhibited monocyte influx by 58% when dosed at
30 mg/kg (ip).
It is interesting to note that for the diastereomers
shown in Figure 2, the 1S,3R-configuration is far
more potent than the 1R,3S-configuration (4c vs 4d,
4f vs 4g, 4i vs 4j). Compound 4i was found to be
the most potent with an IC50 of 80 nM in hCCR2
membrane binding assay.
In conclusion, we have identified a series of phenyl
piperidine derivatives as potent and selective CCR2
antagonists. Compound 3g shows good to excellent
selectivity over CCR1, CCR3, and 5-HT and has an
excellent P450 profile. Further optimization of potency
The synthetic route to prepare compounds of structure 3
is shown in Scheme 1. An appropriate piperidin-4-yl-
alcohol was acylated with the desired acid chloride.
The resulting alcohol was treated with methanesulfonyl
Table 3. Additional biological data for compound 3g
N
Cl
N
Cl
Cl
O
Assay
Condition
Parameter
Result
Binding
Whole cells
Membranes
IC50
IC50
0.3 lM
0.3 lM
Chemotaxis
Cell based assay
IC50
IC50
0.4 lM
Inhibition of cytochrome
P450’s
1A2 3A4
2C9 2C19
2D6
>40 lM
Metabolism
Human liver microsomes
T1/2
>100 min
CCR specificity
CCR1
CCR3
% inhibition
at 25 lM
0%
29%
5-HT selectivity
PK (rat)
5-HT1A, 5-HT1B, 5-HT2A, 5-HT3, 5-HT5A, 5-HT6
1 mg/kg iv
% inhibition at 1 lM
—
Cmax
Tmax
T1/2
Cl
3.4 lM
0.1 h
6.0 h
0.22 mg/kg/lM h
1.4 lM
17 h
30 mg/kg po
Cmax
Tmax
T1/2
9.5 h
Oral bioavailability
19%
N
n
O
n
MsO
N
n
HO
O
O
R1
Cl
O
N
N
c
a
b
HO
n
+
NH
R2
R2
R2
R2
3
Scheme 1. Synthesis of the compound 3. Reagents: (a) Et3N, CH2Cl2; (b) CH3SO2Cl, Et3N, CH2Cl2; (c) substituted phenyl piperidines, CH3CN,
Et3N, reflux.

M. Xia et al. / Bioorg. Med. Chem. Lett. 17 (2007) 5964–5968
5967
Table 4. Cyclopentylamine analogs 4
O
R2
N
N
H
R1
Compound
R1
R2
CCR2 binding IC50 (lM)
4a (cis-Racemate)
4b (cis-Racemate)
4-Methoxy
4-Methoxy
4-Methoxy
4-Methoxy
4-Methoxy
4-Methoxy
4-Methoxy
4-Methoxy
4-Methoxy
4-Methoxy
3,4-Difluoro
3,4-Dichloro
3,5-Dichloro
3,5-Dichloro
3,5-Dichloro
3,5-Difluoro
3,5-Difluoro
3,5-Difluoro
3,4,5-Trifluoro
3,4,5-Trifluoro
3,4,5-Trifluoro
3,5-Difluoro
0.14
0.18
0.16
6.45
0.24
0.16
4c (1S,3R-Enantiomer)
4d (1R,3S-Enantiomer)
4e (cis-Racemate)
4f (1S,3R-Enantiomer)
4g (1R,3S-Enantiomer)
4h (cis-Racemate)
12.0
0.13
0.08
8.40
0.79
4i (1S,3R-Enantiomer)
4j (1R,3S-Enantiomer)
4k (cis-Racemate)
R
S
S
R
17. Brodmerkel, C. M.; Huber, R.; Covington, M.; Diamond,
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N
N
NH
O
NH
R
R
Ar
Ar
O
Figure 2. Cyclopentylamine diastereomers.
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25. The binding affinities were evaluated in THP-1 cells. THP-
1 cells were incubated with 0.5 nM 125I labeled MCP-1
(Perkin-Elmer Life Sciences, Inc., Boston, MA) in the
presence of varying concentrations of either unlabeled
MCP-1 (R&D Systems, Minneapolis, MN) or test com-
pound for 2 h at 30 ꢁC in a 96-well plate. Cells were then
harvested onto a filter plate, dried, and 20 lL of Micro-
scint 20 was added to each well. Plates were counted in a
TopCount NXT, Microplate Scintillation & Luminescence
Counter (Perkin-Elmer Life Sciences, Inc., Boston, MA).
Blank values (buffer only) were subtracted from all values
and drug treated values were compared to vehicle treated
values. One micromolar cold MCP-1 was used for non-
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5968
M. Xia et al. / Bioorg. Med. Chem. Lett. 17 (2007) 5964–5968
specific binding. MCP-1 induced chemotaxis was run in a
and bottom chambers. Cells were allowed to chemotaxis
for 3 h at 37 ꢁC and 5% CO2. An aliquot of the cells which
had migrated to the bottom chamber was taken and
counted then compared to vehicle. All data represent
mean values.
24-well chemotaxis chamber. MCP-1 (0.01 lg/mL) was
added to the lower chamber and 100 lL of THP-1 cells
(1 · 10 7 cell/mL) was added to the top chamber. Varying
concentrations of test compound were added to the top