Discovery and SAR of 5-aminooctahydrocyclopentapyrrole-3a-carboxamides as potent CCR2 antagonists

Article abstract of DOI:10.1016/j.bmcl.2013.05.024

SAR study of 5-aminooctahydrocyclopentapyrrole-3a-carboxamide scaffold led to identification of several CCR2 antagonists with potent activity in both binding and functional assays. Their cardiovascular safety and pharmacokinetic properties were also evalu

Full text of DOI:10.1016/j.bmcl.2013.05.024

Bioorganic & Medicinal Chemistry Letters xxx (2013) xxx–xxx
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Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Discovery and SAR of 5-aminooctahydrocyclopentapyrrole-3a-
carboxamides as potent CCR2 antagonists
⇑
Chaozhong Cai , Dave F. McComsey, Cuifen Hou, John C. O’Neill, Evan Opas, Sandra McKenney,
Dana Johnson, Zhihua Sui
Janssen Research and Development, L.L.C. Welsh & McKean Roads, Spring House, Box 776, PA 19477, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
SAR study of 5-aminooctahydrocyclopentapyrrole-3a-carboxamide scaffold led to identification of sev-
eral CCR2 antagonists with potent activity in both binding and functional assays. Their cardiovascular
safety and pharmacokinetic properties were also evaluated.
Received 11 March 2013
Revised 30 April 2013
Accepted 7 May 2013
Available online xxxx
Ó 2013 Published by Elsevier Ltd.
Keywords:
CCR2 antagonist
Carbamate
1,3-Dipolar cycloaddition
Optimization
Chemokines (chemotactic cytokines) are low molecular weight
proteins (8–10 kDa), and involved in recruiting, chemo-trafficking
and activation of leukocytes such as monocytes, macrophages,
lymphocytes, activated T cells, dendritic cells, eosinophils, baso-
philes, natural killer (NK) cells, by acting as a chemoattractant to
guide the migration of cells. Based on the position of the cysteine
residues, the chemokine family can be classified into four families:
the C, CC, CXC and CX3C chemokines.1 The Monocyte Chemoattrac-
tant Protein-1 (MCP-1), also known as CC chemokine ligand-2
(CCL2), is a member of the CC chemokine which specifically acts
on monocytes and some T cells in inflammatory reactions.2 The
biological effects of MCP-1 are reflected by binding to its primary
receptor, the CC chemokine receptor-2 (CCR2). This MCP-1 driven
activation of CCR2 initiates a cascade of intracellular signaling
events which might be associated with a variety of diseases such
as rheumatoid arthritis (RA),3 atherosclerosis,4 multiple sclerosis,5
inflammatory airway diseases,6 neuropathic pain7 and diabetic
nephropathy.8 Growing evidence suggests that interrupting the
MCP-1-CCR2 axis by mutant MCP-1,9 anti-MCP-1 antibodies10 or
peptide CCR2 antagonists11 inhibits the progression of those
CCR2-dependent diseases. Therefore, blocking CCR2 could provide
a potential approach for development of novel therapy.
tion. To date, significant progress has been made and several differ-
ent chemotypes of CCR2 agonists have already advanced into
clinical trials.12 In our previous manuscript,13 we disclosed a series
of potent 2-aminooctahydrocyclopentalene-3a-carboxamides A as
CCR2 antagonists. To eliminate one chiral center and provide a
more chemically accessible handle, we replaced the carbon at the
7 position with a nitrogen and discovered a novel series of 5-ami-
no-octahydrocyclopenta-pyrrole-3a-carboxamides 1 (Fig. 1). Here
in, we report the synthesis and biological evaluation of this new
scaffold.
The synthesis of the unsubstituted pyrrolidinone 11 was illus-
trated in Scheme 1. Commercially available 2 was converted to es-
ter
3 A 1,3-dipolar
according to the reported procedure.14
cycloaddition of 3 gave optically pure diastereoisomer 4 as the ma-
jor isomer. Removal of the benzyl group by hydrogenation and
subsequent protection with a Cbz group generated 6. A hydrolysis
/ coupling sequence afforded compound 8. Deprotection of the Boc
group, followed by a reductive amination gave compound 10. Fi-
nally, removal of the Cbz group by hydrogenation led to the target
CF3
CF3
In the last decade, enormous efforts have been invested by
many research laboratories including ours to find small molecules
acting as mediators of biological phenomenon such as inflamma-
OMe
OMe
O
O
H
N
H
N
N
N
N
N
R1
R2
O
O
7
N
R
H
H
A
1
⇑
Corresponding author. Tel.: +1 215 628 7845; fax: +1 215 540 5612.
E-mail address: ccai@its.jnj.com (C. Cai).
Figure 1.
0960-894X/$ - see front matter Ó 2013 Published by Elsevier Ltd.
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C. Cai et al. / Bioorg. Med. Chem. Lett. xxx (2013) xxx–xxx
Table 1
O
O
OMe
N
O
H
N
SAR of aliphatic and aromatic analogs
H
N
HN
a, b
c
d
e
Boc
Boc
OMe
CF3
Bn
H
OMe
H
O
2
3
4, pure enantiomer
N
N
N
O
N
O
O
O
H
R
H
OMe
NH
OH
H
OMe
N
H
N
H
N
g
N
f
Compd
R
hCCR2 IC50 (nM)
Binding
hERG IC50
Binding
(lM)
Boc
Boc
Boc
N
Cbz
CTXb
Cbz
H
H
11
12
13
14
H
Me
Et
780
300
629
1215
770
320
nt
>50
>50
42.6
>50
6
7
5
CF3
CF3
iPr
nt
O
O
H
j
15
180
nt
42.1
N
N
h
N
N
H2N
N
i
Boc
O
16
17
126
62
nt
90
>50
22.9
Ph
N
N
Cbz
Cbz
H
H
S
18
152
nt
nt
>50
>50
8
9
N
N
CF3
CF3
19
1300
N
OMe
OMe
O
O
H
H
N
aSingle enantiomers for the central bicycle core; mixtures of diastereoisomers for
methoxytetrahydropyranyl moiety.
k
N
N
N
N
N
O
O
b
MCP-1 induced chemotaxis in THP-1 cells (Ref. 15).
N
NH
Cbz
H
H
size of the substitution and the basicity on the nitrogen atom. This
prompted us to search for appropriate substitution which could re-
duce the basicity of the nitrogen atom while also filling the binding
pocket.
The first set of non-basic analogs, the amide and urea deriva-
tives, were prepared either directly from unsubstituted 11 or from
amine 20 (Scheme 3). Thus, hydrogenation of 8 gave amine 20. Car-
bonylation of 20 or 11 with an acid or an acid chloride gave the
amide. Condensation with isocyanate gave the urea except for
unsubstituted urea 27, which was prepared by hydrolysis of
cyanoamide 21 (Scheme 4). Cyanoguanidine 31 was obtained from
condensation of 11 and sodium dicyanamide.
11
10
Scheme 1. Regents and conditions: (a) HCl, MeOH, reflux; (b) (Boc)2O, TEA, DCM,
0 °C to rt; (c) DBU, DCM; (d) TMSCH2N(CH2OMe)Bn, 5% TFA in DCM; (e) H2, Pd(OH)2,
MeOH, 25 psi, rt; (f) CbzCl, TEA, DCM, 0 °C to rt; (g) 6N KOH, THF; (h) the amine,
EDAC, HOBt, TEA, THF; (i) TFA, DCM; (j) 3-methoxydihydro-2H-pyran-4(3H)-one,
NaBH(OAc)3, TEA, DCM; (k) H2, Pd/C, MeOH.
compound 11. Evan though the central bicyclic core is optically
pure, 11 and all compounds discussed in this paper are a mixture
of 4 possible diastereoisomers due to the two chiral centers on
the methoxytetrahydropyanyl moiety.
Compound 11 was subjected to substitution on the endocyclic
nitrogen atom to provide a variety of analogs. For example, alkyl-
ation on the nitrogen was fulfilled by reductive amination of 11
with corresponding aldehyde (12, 13), ketone (14, 16), and ketone
derivative (15) (Scheme 2). Aromatic substitution was achieved by
cross-coupling of 11 with phenyl boronic acid (17) or aryl bro-
mides (18, 19).
Initial SAR of the R group was evaluated and summarized in Ta-
ble 1. As a starting point, compound 11 possessed an IC50 of
780 nM in binding affinity. Methylation of 11 afforded the more
potent compound 12 (IC50 = 300 nM). Increasing size of substitu-
tion (R) from Me (11), Et (13) to i-Pr (14) showed decreasing po-
tency. On the other hand, the potency of analogs with less
flexible substitution such as aliphatic rings (15, 16) or aromatic
groups (17, 18), increased slightly. The improved potency of cyclic
substitution over acyclic ones may come from their entropic con-
tribution (14 vs 15). In the case of 19, loss of activity may result
from the enhanced basicity from the pyrimidinyl group. This early
SAR indicated that CCR2 activity was mostly influenced by both the
As shown in Table 2, reduction of the basicity at the nitrogen by
the acetylation of 11 led to a moderately potent compound 22 (Ta-
ble 2). Unsaturated amides (23, 24, 25) exhibited double digit
nanomolar activity both in binding and functional assays. The most
potent compound 23 suffered from potential cardiovascular liabil-
ity in hERG screening. Saturation of the double bond in 23 provided
26, which suppressed the hERG inhibition, but failed to return the
potency. To our delight, non-basic urea moieties were also toler-
ated. Unsubstituted urea 27 and its bioisostere 31 exhibited low
nanomolar binding affinities and potently inhibited MCP-1-in-
duced chemotaxis, without hERG activity (IC50>50 lM). Both meth-
ylated urea 28 and isopropylated urea 29 barely retained activity.
Aryl substituted urea (30) resulted in loss of activity. eADME pro-
CF3
CF3
O
O
H
N
H
N
b
N
N
N
N
a
Boc
Boc
8
N
NH
R
H
H
CF3
20
steps i, j in Scheme 1
OMe
O
H
N
CF3
a or b
N
N
11
O
R: Me, Et, iPr,
Ph (c);
(a);
(b);
(e)
or c
or d
or e
OMe
O
H
N
O
N
N
S
N
N
N
N
(d);
c
R
H
11
O
N
R
Scheme 2. Regents and conditions: (a) aldehyde/ketone, NaBH(OAc)3, DCM (for 12,
13, 14, 16); (b) (1-ethoxycyclopropoxy)-trimethylsilane, NaBH3CN, AcOH, MeOH,
reflux (for 15); (c) PhB(OH)2, Cu(OAc)2, 2,6-lutidine, myristic acid, toluene, rt (for
17); (d) 2-bromothiazole, KF, TEA, EtOH, 90 °C (for 18); (e) 2-bromopyrimidine, TEA,
EtOH, 90 °C (for 19).
H
Scheme 3. Regents and conditions: (a) H2, Pd(OH)2, MeOH, 25 psi, rt; (b) acid
chloride, TEA, DCM, 0 °C (for 22, 23, 26); or isocyanate, THF, rt (for 28, 29, 30); (c)
the acid, EDAC, HOBt, TEA, DCM, rt (for 24, 25).
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C. Cai et al. / Bioorg. Med. Chem. Lett. xxx (2013) xxx–xxx
3
Table 3
SAR of carbamate
CF3
CF3
a
CF3
b
O
O
O
CF3
N
N
N
N
N
N
c
OMe
O
11
H
N
N
NH2
CN
N
N
NH2
N
N
CN
H
H
H
N
O
O
27
21
31
N
O
R1
H
O
Scheme 4. Regents and conditions: (a) BrCN, K2CO3, ACN, rt; (b) TEA, DCM, rt; (c)
NaN(CN)2, 5% H2O in i-PrOH, 120 °C.
Compd
R1
hCCR2 IC50 (nM)
hERG IC50
Binding
(lM)
Binding
CTX
33
34
Me
Ph
410
560
69
950
>50
>50
Table 2
SAR of amide, urea and cyanoguanidine
Ph
35
36
118
59
190
99
>50
>50
CF3
OMe
O
H
N
37
38
35
82
21
41
>50
>50
N
N
OMe
O
O
N
39
32
65
>50
R
H
O
Compd
R
hCCR2 IC50 (nM)
hERG IC50
Binding
(lM)
40
41
42
31
45
33
32
18
28
>50
>50
>50
Binding
CTX
NHAc
N
O
O
22
23
395
230
33
>50
O
N
43
41
97
>50
30
24.1
Ph
⁄Single enantiomers for the central bicycle core; mixtures of diastereoisomers for
methoxytetrahydropyranyl moiety.
O
O
24
25
68
87
88
39
>50
gave intermediate 32. Deprotection and alkylation on the left part
of 32 led to carbamates 33 to 43.
49.6
In-vitro screening result of the carbamates is summarized in Ta-
ble 3. Methyl carbamate 33 possessed moderate binding affinity,
but good activity in the chemotaxis (CTX) functional assay.
Replacement of methyl by phenyl (34) resulted in a greater than
10-fold loss of hCCR2 activity in CTX. Increasing flexibility (35)
brought some degree of activity back. Further replacement of phe-
nyl with an aliphatic group (36, 37) showed a trend of increasing
activity. It was also observed that activity was retained with oxy-
gen or nitrogen-containing groups on the ester side (38 to 43). This
finding indicates that there may be binding to a polar or H-bonding
residue in the pocket (Table 3).
Selected potent carbamates were further evaluated in PK study.
For example, in rat PK (oral dose at 10 mpk in 0.5% methocel), com-
pound 40 showed better maximum plasma concentration (Cmax:
145 ng/mL) and oral exposure (AUC: 427 h ng/ml) than urea
27(Cmax: 70.6 ng/mL, AUC: 74 h ng/ml). It also exhibited signifi-
cantly greater CCR2 selectivity over hERG inhibition in binding
O
26
27
110
64
87
27
>50
>50
Ph
O
O
NH2
28
29
30
31
77
71
>50
>50
>50
>50
N
H
O
O
410
57
81
N
H
220
29
N
H
CN
Ph
N
37
NH2
⁄Single enantiomers for the central bicycle core; mixtures of diastereoisomers for
methoxytetrahydropyranyl moiety.
and function assay (PatchXpress: 7.3% at 3
suitable for further characterization.
lM), and was ideally
filing of selected potent compounds (27, 28 and 31) showed low
oral exposure in mouse PK due to their poor lipophilicity. For
example, the CLogD (at pH 7)16 of urea 27 and cyanoguanidine
31 are -3.1 and -2.1, respectively. To decrease the polarity of target
molecules, we turned our attention to carbamates.
Synthesis of the carbamate is illustrated in Scheme 5. The car-
bamoylation of 20 either with available chloroformate (33 to 37),
or alcohol and N, N’-disuccinimidyl carbonates (DSC) (38 to 43)
In summary, we identified a series of novel CCR2 antagonists
feathering 5-amino-octahydrocyclopentapyrrole-3a-carboxamides
as the core structure and systemically evaluated the SAR for the
substitution on its endocyclic nitrogen atom. The early SAR explo-
ration afforded compound 27, which possessed good CCR2 binding
affinity and functional activity, and showed no safety liability. Fur-
ther optimization led to compound 40 which retained good CCR2
activity, and also displayed low cardiovascular liability and good
OMe
O
steps i, j in
Scheme 1
O
O
H
N
H
N
H
N
N
N
N
a
Boc
Boc
or b
O
O
N
O
NH
N
R1
R1
H
H
H
O
O
20
32
33-43
Scheme 5. Regents and conditions: (a) ClCOR1, TEA, DCM, 0 °C to rt (for 33, 34, 35, 36, 37); (b) R1OH, DSC, DMAP, ACN, DCM, DMF, rt (for 38, 39, 40, 41, 42, 43).
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Acknowledgments
The authors thank the ADME/PK, Secondary Pharmacology and
Lead Generation Biology Teams, Center of Excellence for Cardiovas-
cular Safety Research for their contributions to this work. We are
also grateful to Dr. Christopher Teleha for providing a large quan-
tity of intermediate 11.
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and 100
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counted then compared to vehicle.
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L of THP-1 cells (1 Â 107 cell/mL) was added to the top chamber.
l
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16. CLogD value was calculated from Third Demension owned by JNJ.
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