Novel sulfone-containing di- and trisubstituted cyclohexanes as potent CC chemokine receptor 2 (CCR2) antagonists

Article abstract of DOI:10.1016/j.bmcl.2009.05.041

Potent sulfone-containing di- and trisubstituted cyclohexanes were synthesized and evaluated as CC chemokine receptor 2 (CCR2) antagonists. This led to the trisubstituted derivative 54, which exhibited excellent binding (CCR2 IC₅₀ = 1.3 nM) and functional antagonism (calcium flux IC₅₀ = 0.5 nM and chemotaxis IC₅₀ = 0.2 nM). The superiority of the trisubstituted scaffold was rationalized to be the result of a conformational rigidification, which provided insight into the bioactive conformation of this chemotype.

Full text of DOI:10.1016/j.bmcl.2009.05.041

Bioorganic & Medicinal Chemistry Letters 19 (2009) 3418–3422
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Novel sulfone-containing di- and trisubstituted cyclohexanes as potent CC
chemokine receptor 2 (CCR2) antagonists
*
Robert J. Cherney , Ruowei Mo, Dayton T. Meyer, Matthew E. Voss, Yvonne C. Lo, Gengjie Yang,
Persymphonie B. Miller, Peggy A. Scherle, Andrew J. Tebben, Percy H. Carter, Carl P. Decicco
Research and Development, Bristol-Myers Squibb Company, Princeton, NJ 08543-4000, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
Potent sulfone-containing di- and trisubstituted cyclohexanes were synthesized and evaluated as CC che-
mokine receptor 2 (CCR2) antagonists. This led to the trisubstituted derivative 54, which exhibited excel-
lent binding (CCR2 IC50 = 1.3 nM) and functional antagonism (calcium flux IC50 = 0.5 nM and chemotaxis
IC50 = 0.2 nM). The superiority of the trisubstituted scaffold was rationalized to be the result of a confor-
mational rigidification, which provided insight into the bioactive conformation of this chemotype.
Ó 2009 Elsevier Ltd. All rights reserved.
Received 13 March 2009
Accepted 11 May 2009
Available online 18 May 2009
Keywords:
CCR2
CCR2 antagonist
Chemokine
GPCR
Chemokines are endogenous proteins that assist in the activa-
tion and migration of leukocytes.1 In many autoimmune and
inflammatory conditions, high levels of chemokines have been de-
tected and are associated with the uncontrolled delivery of inflam-
matory cells into the tissues and joints.2 We have been interested
in a CC chemokine, monocyte chemoattractant protein-1 (MCP-1
or CCL2),3 which binds to its cognate receptor, CC chemokine
receptor 2 (CCR2),4 a member of the G-protein coupled receptor
(GPCR) family. This pair has been associated with several diseases
that are characterized by monocyte accumulation, including rheu-
matoid arthritis,5 atherosclerosis,6 and multiple sclerosis7 and
insulin resistance.8 As a result, there has been a substantial interest
in the design and synthesis of CCR2 antagonists.9 In this Letter, we
describe a series of novel, sulfone-containing di- and trisubstituted
cyclohexanes as potent CCR2 antagonists.
As shown in Figure 1, we recently described the disubstituted
cyclohexane 1 as a potent and selective CCR2 antagonist.10 In an at-
tempt to reduce the number of hydrogen bond donors, we began to
explore sulfones 2a and 2b as possible antagonists. As shown in
Scheme 1, the disubstituted cyclohexanes (10–11 and 22–29) were
synthesized in racemic form, starting from the commercial, race-
mic alcohol 3. After carbamate formation, sulfide installation was
accomplished via a displacement reaction11 to give 5. Sulfide oxi-
dation was followed by a SNAr reaction to deliver compound 7.
An initial target was then realized by direct coupling of 8 with gly-
cinamide 9 to yield 10. Amine 8 could also be coupled with N-Boc-
glycine to afford 12. After carbamate removal, the functionalized
anthralinic acids 14–21 (synthesis shown in Scheme 2) were at-
tached via BOP coupling to yield targets 22–29.
The functionalized anthranilic acids were synthesized as shown
in Scheme 2. Carboxylate 30 was protected as an allyl ester by
exposure to allyl bromide and potassium carbonate in DMF to af-
ford 31. Standard deprotection of the carbamate gave aniline 32.
Treatment with triphosgene and the amine of choice gave a urea,12
which only needed the allyl ester removed to afford the function-
alized anthranilic acids 14–21.
As shown in Scheme 3, synthesis of the racemic trisubstituted
scaffold commenced with the racemic epoxide 33.13 A Lewis
acid-promoted epoxide opening was used in conjunction with a
lithiated methyl phenyl sulfone to provide the alcohol 34.14 The
secondary alcohol was converted to azide 35 through the interme-
diacy of the mesylate. The benzyl group of 35 was removed with
15
BCl3 prior to the reduction of azide 36 to amine 37. After the
amine was protected as carbamate 38, a mesylate displacement
reaction provided azide 39. Carbamate removal was followed by
amide formation to give either glycinamide 42 or 43, depending
on the carboxylate (41 or 9) used. In each case, the azide was re-
duced to the amine (44 or 45) and then elaborated to the targets,
as shown in Scheme 2.
The newly synthesized sulfones were evaluated in vitro, using a
radiolabeled MCP-1 displacement assay with peripheral blood
mononuclear cells (PBMCs).16 We were interested in selective
CCR2 antagonists, and therefore, we used a CCR3 binding assay17
for an initial assessment of selectivity. Compounds with good
* Corresponding author. Tel.: +1 609 252 3066; fax: +1 609 252 7446.
E-mail address: robert.cherney@bms.com (R.J. Cherney).
0960-894X/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2009.05.041

R. J. Cherney et al. / Bioorg. Med. Chem. Lett. 19 (2009) 3418–3422
3419
Figure 1. Investigation of sulfone-containing di- and trisubstituted cyclohexanes.
Scheme 1. Reagents and conditions: (a) (Boc)2O, TEA, THF/H2O, 97%; (b) bis(4-bromophenyl) disulfide, PBu3, CH2Cl2, 43%; (c) m-CPBA, CH2Cl2, 77%; (d) NaSMe, DMF, quant.;
(e) TFA, CH2Cl2, quant.; (f) BOP, N-Boc-Gly-OH, DIEA, DMF, quant.; (g) BOP, 9, DMF, 53%; (h) TFA, CH2Cl2, quant.; (i) BOP, 14–21, DIEA, 11–55%; (j) TFA, CH2Cl2, quant.
activity in the CCR2 binding assay were also evaluated in two func-
tional assays: a calcium flux assay16,18 and a chemotaxis assay.16 As
shown in Table 1 for the disubstituted case, a direct comparison of
the previously published10 amide 1 to sulfone 22 showed a fivefold
loss of CCR2 affinity for the sulfone. In order to discover CCR2 affin-
ity for the sulfones, we probed the 2-amino position of the anthra-
nilic amide. The t-butyl carbamate 10, the amino derivative 11, the
ethyl urea 23 or cyclopentyl urea 24 all failed to demonstrate any
additional CCR2 affinity when compared to 22. However, the
diethyl urea 25 gained fourfold in affinity for CCR2 as compared
to 22, without affecting its selectivity versus CCR3. Likewise, the
dimethyl urea 26 also demonstrated this increase in CCR2 binding
affinity. This trend was improved with the cyclic cases of pyrrolid-
inyl 27, azetidinyl 28, and morpholinyl 29, as they displayed both
excellent binding and functional activity. However, these large ur-
eas added significant molecular weight, and we sought ways to cir-
cumvent this.
Recently, we described19
a series of potent trisubstituted
CCR2 antagonists, which featured exocyclic amines in the 4-po-
sition of the cyclohexane, and these antagonists did not need
the large ureas for activity. In an attempt to reduce our require-
ment for the large ureas in the present case (Table 1), we
investigated the installation of exocylic amines in the C-4 posi-
tion of the cyclohexyl sulfone antagonists. As shown in Table 2,
the primary amine 44 displayed excellent CCR2 activity without
the need for an urea on the anthranilic amide, thus lowering
molecular weight. In addition, the primary amine 44 was a po-
tent functional antagonist while remaining selective versus
CCR3. The mono-methyl amine 48 showed a threefold increase
in binding affinity with a corresponding fivefold increase in cal-
cium flux potency as compared to 44. Other secondary amines
(benzyl 49 and i-propyl 50) were also active in the binding as-
say with similar functional activity. Small tertiary amines like
the dimethyl 51, diethyl 52, and i-propyl methyl 54 displayed

3420
R. J. Cherney et al. / Bioorg. Med. Chem. Lett. 19 (2009) 3418–3422
the best binding affinity, with 54 having excellent functional
activity (calcium flux IC50 = 0.5 nM and chemotaxis
IC50 = 0.2 nM). However, as shown by the dipropyl analog 53,
if the tertiary amine became too large, CCR2 binding affinity de-
creased. The CCR2 binding affinity also decreased for non-basic
analogs like the acetamide 55 and the sulfonamide 56. A direct
comparison of the Boc carbamate 57 with its corresponding
disubstituted case 10 demonstrated that the trisubstituted
derivative 57 gained about fourfold in affinity for CCR2. Unex-
pectedly, removal of the carbamate to the trisubstituted 58
led to a 100-fold gain in affinity for CCR2, as compared to the
disubstituted case 11.
Thus, the C-4 exocyclic amine proved to be a valuable substi-
tuent in the CCR2 driven optimization of these sulfone antago-
nists. It is likely that the exocyclic amine makes a new contact
within the CCR2 receptor, however this exocyclic substituent
has another role as well, conferring conformational rigidity to
the cyclohexane core. As shown in Figure 2, disubstituted 11
has two conformations (see 11A and 11B) of essentially the same
energy20 that interconvert via a ring flip, as both substituents
compete for the equatorial position. Installation of the C-4 exocy-
clic amine creates a 1,3-diaxial interaction between the C-4 and
C-2 position (see conformation 58B), thus forcing the cyclohexane
to adopt a single chair, which places the C-4 and C-2 substituent
in the equatorial position as shown by conformation 58A. Hence,
from these considerations, we presume that 58A and 11A repre-
Scheme 2. Reagents and conditions: (a) allyl-Br, K2CO3, DMF, 73%; (b) TFA, CH2Cl2,
quant.; (c) (i) triphosgene, THF, (ii) amine of choice, THF, 48–87%, (iii) Pd(PPn3)4
pyrrolidine, MeCN, 27–53%.
Scheme 3. Reagents and conditions: (a) p-MeSC6H4SO2Me, n-BuLi, BF3ÁEt2O, THF, À78 °C, 65–84%; (b) (i) MsCl, Et3N, CH2Cl2, 0 °C; (ii) NaN3, DMSO, 85 °C, 70% (two steps); (c)
BCl3, CH2Cl2, 84%; (d) H2, Pd/BaSO4, MeOH, 98%; (e) (Boc)2O, NaHCO3, THF/H2O, quant.; (f) (i) MsCl, Et3N, CH2Cl2, 0 °C; (ii) NaN3, DMSO, 85 °C, 76%; (g) TFA, CH2Cl2, quant.; (h)
41 or 9 BOP, NMM, DMF, 96%; (i) H2, Pd/BaSO4, MeOH, 92%; (j) CF3CO2Et, TEA, CH2Cl2, quant.; (k) MeI, K2CO3, DMF, 18%; (l) 2 M K2CO3, MeOH, 89%; (m) aldehyde of choice
(acetone for 50), NaBH3CN, MeOH, 17–36%; (n) (i) acetone, NaBH3CN, MeOH; (ii) 38% HCHO NaBH3CN, MeOH, 91%; (o) AcCl, TEA, CHCl3, 37%; (p) MsCl, TEA, CHCl3, 52%; (q)
TFA, CH2Cl2, quant.

R. J. Cherney et al. / Bioorg. Med. Chem. Lett. 19 (2009) 3418–3422
3421
Table 1
Evaluation of disubstituted cyclohexane derivativesa
CCR3 Binding % Inh@10 l
Mc
b
Compd #
R
IC50 (nM)
CCR2 Binding
Ca2+ Flux
Chemotaxis
1
22
10
11
23
24
25
26
27
28
29
See Figure 1
NHCONHi-Pr
NHBoc
NH2
NHCONHEt
NHCONHC5H9
NHCONEt2
NHCONMe2
NHCON-pyrrolidinyl
NHCON-azetidinyl
NHCON-morpholinyl
5.1 3.6 (2)
26.5 3.5 (2)
46.0 2.8 (2)
172.0 108.9 (2)
27.5 2.1 (2)
44.5 4.9 (2)
6.5 2.1 (2)
8.1 4.0 (2)
3.8 1.6 (2)
5.8 2.2 (2)
2.7 2.2 (2)
18 0.7 (2)
38.0 (1)
NT
1.0 0.2 (2)
NT
NT
NT
NT
37
32.0
9.4
NT
18.1
55.2
3.0
12.9
NT
21.0 (1)
64.0 (1)
34.0 (1)
21.0 (1)
24.0 (1)
6.5 (1)
16.0 (1)
NT
39.5 20.5 (2)
43.5 4 9 (2)
11.8 7.2 (2)
16.5 9.2 (2)
7.0 4.2 (2)
0
24.6 3.7 (2)
21.6 7.5 (2)
a
Compounds are racemic, one enantiomer is displayed for illustrative purposes.
IC50 values (n) are displayed as mean SD (n = 2) and mean SEM (n > 2).
CCR3% inhibition are n = 1, unless otherwise noted. NT = not tested.
b
c
;
;
Table 2
Evaluation of trisubstituted cyclohexane derivativesa
R1
IC50 (nM)
CCR3 Binding % Inh@10 l
Mc
b
Compound #
R
CCR2 Binding
Ca2+ Flux
Chemotaxis
44
48
49
50
51
52
53
54
55
56
57
58
NH2
NHMe
NHBn
NHi-Pr
NMe2
NEt2
Nn-Pr2
Ni-PrMe
NHAc
NHSO2-Me
Ni-PrMe
Ni-PrMe
H
H
H
H
H
H
H
H
13.1 5.1 (5)
3.7 2.3 (2)
8.4 3.7 (2)
2.05 0.2 (2)
0.37 0.07 (2)
1.3 0.7 (2)
199.5 72.8 (2)
1.3 0.5 (2)
153.0 14.1 (2)
41.3 28.6 (2)
12.5 3.5 (2)
1.4 0 (2)
7.5 7.8 (2)
1.5 (1)
NT
5.1 7.7 (3)
0.3 0 (2)
0.7 0.1 (2)
NT
0.5 0.1 (2)
NT
NT
21.0 8.7 (3)
NT
12.7 6.1 (2)
10.4 0.8 (2)
2.5 (1)
NT
NT
0.2 (1)
NT
50.2 3.7 (2)
51.2
83.6
71.6
53.1
69.6
NT
75.5
NT
H
H
NT
42.9
34.6
28.1
NHBoc
NH2
NT
NT
2.3 (1)
1.1 0.8 (2)
a
Compounds are racemic, one enantiomer is displayed for illustrative purposes.
IC50 values (n) are displayed as mean SD (n = 2) and mean SEM (n > 2).
CCR3 % inhibition are n = 1, unless otherwise noted. NT = not tested.
b
c
sent the likely bioactive conformations for these tri- and disubsti-
tuted antagonists.
In summary, we have described the synthesis and evaluation of
novel, sulfone-containing di- and trisubstituted cyclohexanes as
potent CCR2 antagonists. The lower molecular weight and in-
creased potency of the trisubstituted antagonists made them more
attractive, with compound 54 having the best profile. The superior-
ity of the trisubstituted platform was rationalized, in part, to be the

3422
R. J. Cherney et al. / Bioorg. Med. Chem. Lett. 19 (2009) 3418–3422
Acknowledgment
We also thank Dr. Joel C. Barrish for a critical review of the
manuscript.
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unchanged when the compound was incubated alone (without MCP-1 present),
thus validating the compound as an antagonist and not a partial agonist.
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20. Relative energies of 11A, 11B, 58A, and 58B were calculated at the B3LYP/6-
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program qchem (Q-Chem Inc, Pittsburgh, PA). The lower energy conformer
from each pair was arbitrarily set to 0 kcal/mol and the energy of the other
conformer reported relative to it.
Figure 2. Energy-minimized20 conformations of 11 and 58.
result of a conformational rigidification inherent in the trisubsti-
tuted case. This provided structural information on the bioactive
conformation of this chemotype, which should aid in the design
of future CCR2 antagonists.