Synthesis of 3-phenylsulfonylmethyl cyclohexylaminobenzamide-derived antagonists of CC chemokine receptor 2 (CCR2)

Article abstract of DOI:10.1016/j.bmcl.2011.12.057

We report the synthesis of 3-phenylsulfonylmethyl cyclohexylaminobenzamides (4) as CCR2 inhibitors for the potential treatment of inflammatory diseases. Several of the compounds display nanomolar binding affinity for CCR2. The in vitro structure-activity

Full text of DOI:10.1016/j.bmcl.2011.12.057

Bioorganic & Medicinal Chemistry Letters 22 (2012) 1384–1387
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Bioorganic & Medicinal Chemistry Letters
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Synthesis of 3-phenylsulfonylmethyl cyclohexylaminobenzamide-derived
antagonists of CC chemokine receptor 2 (CCR2)
Michael G. Yang, Zili Xiao, Qing Shi, Robert J. Cherney, Andrew J. Tebben, George V. De Lucca,
Joseph B. Santella III, Ruowei Mo, Mary Ellen Cvijic, Qihong Zhao, Joel C. Barrish, Percy H. Carter
⇑
Research and Development, Bristol-Myers Squibb Company, Route 206 & Provinceline Road, 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:
We report the synthesis of 3-phenylsulfonylmethyl cyclohexylaminobenzamides (4) as CCR2 inhibitors
for the potential treatment of inflammatory diseases. Several of the compounds display nanomolar bind-
ing affinity for CCR2. The in vitro structure–activity relationships of 4 are described, and are also recon-
ciled with those from the related 2-phenylsulfonylmethyl series.
Received 6 August 2011
Revised 8 December 2011
Accepted 12 December 2011
Available online 16 December 2011
Ó 2011 Elsevier Ltd. All rights reserved.
Keywords:
CCR2
Chemokine
GPCR
Antagonist
CC chemokine receptor 2 (CCR2) is a G protein-coupled receptor
expressed primarily on monocytes—including so-called ‘inflamma-
tory monocytes’1,2—as well as T-cells, dendritic cells, and endothe-
lial cells. CCR2 binds monocyte chemo-attractant proteins 1–4, a
group of pro-inflammatory chemokines that mediate both cellular
trafficking and activation. Notably, CCR2 plays a role in pre-clinical
models of autoimmune, cardiovascular, and metabolic diseases.3–6
Accordingly, several medicinal chemistry groups have pursued a
strategy of blocking CCR2 interaction to blunt human disease.7–9
We previously reported on a series of 1,2-cis cyclohexylamine
antagonists 1 (Fig. 1).10 In a more recent publication, we demon-
strated that the addition of an amine substituent to 1 significantly
affects the compound’s affinity for CCR2.11 For example, the deriv-
atives of (1,2,4-cis) 3 have shown improved CCR2 inhibitory activ-
ity relative to the analogs of both (1,2-cis) 1 and (1,2,5-cis) 2
(R = NHC(O)Ar, Fig. 1). The (1,2,4-cis) substitution scaffold 3 was
in the preparation of CCR2 inhibitors and its synthesis has been re-
ported.13 Hydrogenation of azide 6 gave amine 7 which was then
coupled to glycinamic acid 8. The Boc group of 9 was removed
by treating it with TFA followed by a reductive amination reaction
to give antagonist 4b. Further reductive amination of 4b with
formaldehyde provided 4c in 90% yield. Racemic 4c was then sep-
arated on a preparative chiral HPLC to give the enantiomerically
pure compounds 4d and 4e, respectively.14
Y
CF3
CF3
5
X
O
H
N
O
H
N
4
2
2
N
H
1
N
H
1
R
O
R
O
X = H, Y = NR2 (1,2,5-cis) 2
X = NR2, Y = H (1,2,4-cis) 3
(1,2-cis) 1
also found to be potent in
a series of sulfone antagonists
(R = CH2SO2Ar, Fig. 1).12 In order to probe more completely the
structure–activity relationships (SAR) of the sulfone substituent,
we investigated the movement of this group from C2 to C3 in the
context of the previously optimized cyclohexyl-1,4-diamine scaf-
fold. In this communication, we report the syntheses of the all
cis- and alternating trans-(1,3,4)-scaffolds 4 and 5 (Fig. 1).
Ra
N
CF3
Move C2 substituent
(R = SO2Ph)
4
Rb
O
H
N
3
*
N
H
1
PhO2S
O
A general synthetic scheme for the preparation of racemic-
(1,3,4)-cis-4 is shown in Scheme 1. The tri-substituted 3-phen-
ylsulfonylmethyl cyclohexylamino core 6 has previously been used
all cis, (1S,3S,4R) 4
(1S,3R,4R) 5
⇑
Corresponding author.
E-mail address: percy.carter@bms.com (P.H. Carter).
Figure 1. Proposed targets of 3-phenylsulfonylmethyl cyclohexylamino benzam-
ides 4 and 5.
0960-894X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2011.12.057

M. G. Yang et al. / Bioorg. Med. Chem. Lett. 22 (2012) 1384–1387
1385
Table 1
H
N
H
N
CF3
CCR2 Binding IC50 values (nM) for cyclohexylglycinamidesa
a
Boc
Boc
O
+
H
N
100%
N3
NH2
HO
O
O
O
O
CF3
CF3
S
S
4
O
8
R
Ph
Ph
R2N
Ph
4
R2N
S
O
H
N
O
H
N
racemic-6
racemic-7
2
3
CF3
R
1
1
N
H
H
N
1
N
H
O
O
O
O
Boc
O
O
b
80%
c,d
S
H
Ph
(1,2,4)-cis-2
(1,3,4)-cis-4
N
O
O
N
H
100% & 56%
O
O
CF3
CF3
S
O
Ph
4
4
R2N
R2N
racemic-9 (R = H)
CF3
O
H
N
O
H
N
3
i-Pr
N
i-Pr
N
CF3
1
N
H
N
H
O
O
H
O
H3C
O
H
S
O
e
H
Ph
N
N
O
(1,3,4)-trans-5
(1,4)-cis-6
N
H
N
H
90%
O
O
O
O
S
O
R
S
R
Ph
Ph
racemic-4b (R = H)
racemic-4c (R = H)
2b
cis-4b
59 11
trans-5b
6
SO2Ph
Compd
NR2
i-Pr
N
CF3
i-Pr
N
CF3
R
a
b
c
NH2
i-PrNH
i-PrNMe
37
5.2 2.3
0.8 0.5
2
3700
310 100
2900
4100
570 160
72 26
H3C
O
R
H3C
O
H
S
H
N
12
3
f
89c
N
N
H
S
S
R
N
H
PhO2S
O
Binding was performed using [125I]MCP-1 and human peripheral blood mono-
a
O
(1S,3S,4R)-4d
(1R,3R,4S)-4e
nuclear cells at RT. Data are typically reported as the mean of two determinations
( standard deviation). See Ref. 18.
b
Scheme 1. Reagents and conditions: (a) H2, Pd-C, EtOH; (b) HATU, i-prNEt, DMF; (c)
TFA, CH2Cl2; (d) iPrCHO, NaBH(OAc)3, CH2Cl2; (e) CH2O, NaBH(OAc)3, CH2Cl2; (f)
chiral HPLC separation.
Compounds 2b, 2c and 5a–c are homochiral as illustrated. Compounds 2a and
4a–c are racemic.
c
Data generated using THP-1 cells instead of hPBMCs. Historical correlation with
PBMC data was very tight (not shown).
CH3
b
Ph
H
CH3
O
O
Ph
NH2
alcohol, followed by a Pd(OH)2/C-mediated hydrogenolysis to give
the corresponding primary amine. The primary amine was then
protected with a Cbz group to provide 16 in 71% yield over three
steps. Thiolation of alcohol 16 with 1,2-diphenyldisulfide gave
the phenylsulfide 17, which was exposed to m-CPBA to provide
the corresponding sulfone 18 in 95% yield. Upon removing the
1,3-dioxolane protecting group, the resulting ketone was treated
with ammonia and sodium triacetoxy-borohydride to give a 1:1
diastereomeric mixture of amines 19. This mixture was separated
by preparative reverse phase HPLC to afford the single isomers
20 and 21.16 With intermediate 20 in hand, the final compounds
5a–c were prepared by using the same reaction path as shown in
Scheme 1, except that the Cbz group was removed by
hydrogenolysis.
We compared the CCR2 binding affinities of (1,3,4)-trisubsti-
tuted cyclohexylamines 4 and 5 versus those of the historical
(1,2,4)-trisubstitued series (Table 1).17,18 Examination of the data
reveals the following three SAR trends: (I) the primary amines 2a
and 4a exhibit moderate and similar CCR2 potencies; (II) in the
cis-(1,2,4)-series, the secondary amine is significantly less active
than its tertiary counterpart (cf. 2b and 2c), whereas the secondary
amine is superior to its tertiary counterpart in the cis-(1,3,4) series
(cf. 4b and 4c); and (III) the alternating trans-(1,3,4) isomer is sig-
nificantly less potent relative to its all cis counterpart (cf. 4a–c and
5a–c). Given that compounds 4a–c were racemic, we could not dis-
tinguish between the relative contributions of the true cis-(1,3,4)-
isomer and the pseudo cis-(1,4,5) isomer (see 4d and 4e, Scheme
1). After chiral HPLC separation.14 and biological analysis, it was
clear that the true cis-(1,3,4) isomer 4d was markedly more potent,
as it exhibited a binding IC50 value of 79 nM, whereas 4e did not
bind at concentrations up to and including 2,500 nM. Together
with the data on 5a–c, this result suggests that the placement of
the phenylsulfonylmethyl appendage is critical, in both a regio-
and stereochemical sense.
a
O
O
N
O
O
64% over
2-steps
O
EtO2C
EtO2C
O
11
Ph
12
13
Ph
CH3
CH3
N
e,f,g
d
c
N
H
H
O
71% over
O
55% over
EtO2C
3-steps
EtO2C
2-steps
O
O
15
14
H
N
H
N
H
N
Cbz
Cbz
Cbz
h
i
O
O
O
O
98%
95%
O
O
O
S
S
OH
Ph
Cbz
Ph
Ph
O
16
17
H
18
H
H
N
N
N
Cbz
Cbz
Ph
j,k
l
NH2
NH2
NH2
95% &
56%
S
O
S
O
S
O
Ph
19
chiral-20
chiral-21
O
O
O
Scheme 2. Reagents and conditions: (a) NaH, EtOCO2Et, THF, reflux; (b) Yb(OTf)3,
benzene, reflux; (c) NaBH(OAc)3, MeCN, MeCO2H; (d) NaOtBu, THF; (e) LAH, Et2O;
(f) H2, 20% Pd(OH)2/C, MeOH; (g) Cbz-Cl, K2CO3, CH2Cl2; (h) PhS-SPh, Bu3P, CH3CN;
(i) m-CPBA, CH2Cl2; (j) HCl, acetone, reflux; (k) NH3, NaBH(OAc)3, dioxane; (l) HPLC
separation using a phenomenex column with MeOH/H2O mixture as the gradient.
To study the potential effect of stereochemical configuration on
CCR2 binding activity, the alternating trans-isomer 5 was also
desired. A synthetic scheme for the preparation of the key interme-
diate 20 is illustrated in Scheme 2. Acylation of 11 with diethyl
carbonate provided ketoester 12 which was then exposed to
(R)-1-phenylethanamine to form the corresponding enamine 13
in 64% yield over two steps. Diastereoselective reduction15 of 13
with NaBH(OAc)3 gave the cis-isomer 14, which was subsequently
isomerized, under basic conditions to the thermodynamically pre-
ferred trans-isomer 15 in 55% yield. Ester 15 was reduced to an
In order to probe further the role of the phenylsulfonylmethyl,
we synthesized and tested the simple disubstituted cis-(1,4)

1386
M. G. Yang et al. / Bioorg. Med. Chem. Lett. 22 (2012) 1384–1387
isomer 6, which lacked this moiety (Table 1).19 As expected, com-
pounds 6a–b were similar in potency to 5a–b and clearly less po-
tent than either 2a–b or 4a–b (Table 1). However, to our surprise,
the simple disubstituted 6c was more potent than 5c and 4e, and
equipotent to 4d. Thus, while regio- and stereodefined placement
of the sulfone is important for CCR2 affinity, the substitution of
the amine also needs to be matched to the sulfone regioisomer
in order to achieve optimal affinity.
Table 2
CCR2 Binding IC50 values (nM) for phenylsulfonylmethyl benzamides 4f–4pa
CF3
CF3
R2N
R2N
O
H
N
O
H
N
N
H
N
H
O
O
S
O
S
O
N
O
Ph
Ph
H
O
O
racemic-cis-4 (f-l)
racemic-cis-4 (m-p)
N
We turned to molecular modeling to rationalize the observa-
tions from Table 1.20 The basis of the preferred stereochemistry
(cis- vs alternating trans-) in the (1,3,4)-series becomes clear when
one examines an overlay of the secondary amines 2b, 4b, and 5b
(Fig. 2A). As illustrated, it is possible to achieve good alignment
of the key functionalities—isopropylamine, phenylsulfone, and gly-
cinamide—between 2b and 4b because of the relative placement of
the substituents on the cyclohexyl ring. The low energy conforma-
tion of 2b places the glycinamide in an axial orientation, forcing
the isopropylamine and phenylsulfone to be equatorial. In contrast,
the isopropopylamine in 4b is axial, with both the phenyl sulfone
and gycinamide equatorial. The relative flipping of the cyclohexyl
ring allows good alignment of 2b and 4b. However, it is not possi-
ble to achieve such overlap between all substituents of 2b and 5b
in either conformation of the cyclohexyl ring, and the impact of the
phenylsulfone on CCR2 potency is thus lost (cf. 5b and 6b, Table 1).
As expected, the basis of the interplay between the amine sub-
stitution and regiochemistry of the phenylsulfonylmethyl group is
more subtle. In the (1,3,4)-regioisomers 4c and 5c, we propose that
the proximity of the methylene off the phenylsulfone group to the
protonated tertiary amine forces a projection of the amino NH to-
ward this substituent in order to avoid an unfavorable steric inter-
action with the amino N-methyl group (Fig. 2B). In the case of 2c,
the methylene is distant enough to allow the amine to adopt the
opposite stereochemistry, thereby exposing the conformation with
the amino NH opposite the phenyl sulfone (Fig. 2B). We infer that
this conformation is preferred in order to facilitate a better interac-
tion with Glu291 of CCR2, a residue that has been shown to form a
key contact with several different classes of CCR2 antagonists.21 In
summary, in the context of amine substitution, it is the regiochem-
istry of the phenyl-sulfonylmethyl (C2 vs C3) that is more impor-
tant than its stereochemistry, consistent with the SAR data for
C2, C3, and unsubstituted series 2, 4/5, and 6 (Table 1).
Entry
Substrate
NR2
IC50 (nM)
12
1
2
3
4
5
6
7
8
4b
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
i-PrNH
MeNH
EtNH
n-PrNH
c-BuNH
NMe2
n-PrNMe
c-C5H10
NH2
3
180 12
27 11
54 11
34 16
130 16
370 98
340 69
6.6 3.6b,c
12b
N
9
10
11
12
EtNH
i-PrNH
i-PrNMe
6.6 0.4b
34b
a
Except where indicated, binding was performed using [125I]MCP-1 and human
peripheral blood mononuclear cells at RT. Data are typically reported as the mean of
two determinations ( standard deviation). See Ref. 18 for assay protocol.
Data were generated using THP-1 cells. Historical correlation with PBMC data
was good (not shown).
b
c
A different lot of 4m exhibited an IC50 of 1.4 nM in PBMC binding.
addition, we observed that the incorporation of a urea moiety at
the 2-position of the aromatic ring sometimes enhanced the
CCR2 binding affinity (cf. Tables 1 and 2). Among these analogs,
4m and 4o were the most potent CCR2 antagonists, with binding
IC50 values of 6.6 nM in THP-1 cells. In order to document selectiv-
ity over CCR5, a binding assay with MIP-1b was performed.22 Com-
pounds 4m and 4o displayed binding CCR5 IC50 values of 7,300 and
810 nM, respectively, indicating greater than 100-fold selectivity
for binding CCR2 over CCR5. Finally, urea 4m was also studied in
a monocyte transmigration assay,22 and exhibited IC50 values of
8 and 10 nM in the presence of 0.1% and 0.5% BSA, respectively.
A number of compounds were tested in the liver microsome
stability assay (Table 3). The data reveal that both secondary and
tertiary amines (4b–4j) are prone to oxidative de-alkylation reac-
tions. The microsomal stability data is especially unfavorable for
isopropyl amine and dimethyl amine-derived analogs (4b and
4j). On the other hand, the primary amine derivatives (4a and
4m) exhibit good microsomal stability in all three species (entries
1 and 6, Table 3). Unfortunately, when compound 4m was dosed in
In order to extend our understanding of this series and optimize
further its CCR2 affinity, we synthesized additional analogs of cis-
(1,3,4) 4 (see Table 2). As in the cis-(1,2,4) series,12 the iso-propyl
group appeared to be the optimal amine substituent (cf. 4b and
4f–4i). As noted in Table 1, secondary amines were more typically
potent than their tertiary counterparts (4f–i vs 4j–l, Table 2). In
Figure 2. (A) Alignment of secondary amines 2b (green), 4b (yellow), and 5b (cyan). (B) Alignment of the protonated forms of tertiary amines 2c (green), 4c (yellow) and 5c
(cyan). The amino proton for all compounds is shown in white; the N-Me is oriented away from the viewer. See discussion in text above.

M. G. Yang et al. / Bioorg. Med. Chem. Lett. 22 (2012) 1384–1387
1387
Table 3
6. Kang, Y. S.; Cha, J. Jo.; Hyun, Y. Y.; Cha, D. R. Exp. Opin. Invest. Drugs 2011, 20,
745.
Metabolic stability assessed by liver microsomesa
7. Carter, P. H.; Cherney, R. J.; Mangion, I. K. Ann. Rep. Med. Chem. 2007, 42, 211.
8. Xia, M.; Sui, Z. Exp. Opin. Ther. Pat. 2009, 19, 295.
Entry
Substrate (–NR2)
Human
Rat
Mouse
9. Struthers, M.; Pasternak, A. Curr. Top. Med. Chem. 2010, 10, 1278.
10. Cherney, R. J.; Mo, R.; Meyer, D. T.; Nelson, D. J.; Lo, Y. C.; Yang, G.; Scherle, P. A.;
Mandlekar, S.; Wasserman, Z. R.; Jezak, H.; Solomon, K. A.; Tebben, A. J.; Carter,
P. H.; Decicco, C. P. J. Med. Chem. 2008, 51, 721.
11. Cherney, R. J.; Brogan, J. B.; Mo, R.; Lo, Y. C.; Yang, G.; Miller, P. B.; Scherle, P. A.;
Molino, B. F.; Carter, P. H.; Decicco, C. P. Bioorg. Med. Chem. Lett. 2009, 19, 597.
12. Cherney, R. J.; Mo, R.; Meyer, D. T.; Voss, M. E.; Lo, Y. C.; Yang, G.; Miller, P. B.;
Scherle, P. A.; Tebben, A. J.; Carter, P. H.; Decicco, C. P. Bioorg. Med. Chem. Lett.
2009, 19, 3418.
1
2
3
4
5
6
4a (–NH2)
100
4.4
24
11
4.4
70
57
0.9
23
8
3.9
71
96
9.6
25
28
4.3
87
4b (–NHiPr)
4g (–NEtH)
4h (–NHnPr)
4j (–NMe2)
4m (–NH2)
a
Metabolic stability is defined as the percentage of parent compound remaining
over 10 min of incubation time in the presence of human, rat, and mouse liver
microsomes, respectively. The initial compound concentration was 0.5 M.
13. Carter, P. H.; Cherney, R. J.; Batt, D. G.; Duncia, J. V.; Gardner, D. S.; Ko, S. S.;
Srivastava, A. S.; Yang, M. G. PCT Int. Appl. WO/PCT 2005021500, 2005.
14. The absolute stereochemical assignments of 4d and 4e were confirmed by an
l
independent synthesis of 4e from
a
known enantiomerically pure
intermediate. See Ref. 13
15. Cimarelli, C.; Palmieri, G. J. Org. Chem. 1996, 61, 5557.
16. The stereochemical assignments of 20 and 21 were confirmed by NMR
analyses on closely related compounds. Note that compounds derived from 21
were inactive towards CCR2 binding.
mice by oral gavage, significant circulating levels were not de-
tected. Thus, further optimization in this series is required in order
to identify a compound with oral bioavailability.
In summary, we have found that 3-phenylsulfonylmethyl cyclo-
hexylaminobenzamides are potent antagonists of CCR2. Our studies
revealed a strong dependence on the regio- and stereochemical dis-
position of the phenylsulfonylmethyl group, along with an unex-
pected ‘pairing’ of the regiochemistry of this substituent with the
substitution pattern of the exocyclic amine. Further studies on
trisubstituted cyclohexanes as CCR2 antagonists will be reported
in due course.
17. For preparation of the (1,2,4)-trisubstituted analogs, see Ref. 12,13
18. Carter, P. H.; Cherney, R. J. PCT Int. Appl. WO2002/050019, 2002.
19. For the preparation of compounds 6a–c, see Carter, P. H.; Cherney, R. J.; Batt, D.
G.; Brown, G. D.; Duncia, J. V.; Gardner, D. S.; Yang, M. G. PCT Int. Appl.
WO2005/020899, 2005.
20. Conformational searching of 2b, 4b, 5b, 2c, 4c, and 5c, was carried out using
the conformational search module of Macromodel v9.7 (Schrodinger, Inc.) and
the OPLSAA-2005 force field in vacuum. Conformations were retained if they
differed by 0.5A RMSD and had an energy <5 kcal/mol higher than the global
minimum. Pairwise overlays of the resulting conformations of 2b and 4b were
generated using ROCS (Openeye, Inc.) ranked by comboscore. The overlays
were inspected and the best overlap selected. The conformation of 2b from this
overlap was then used as the template molecule for the overlay of 5b. An
identical sequence was used to align 2c, 4c, and 5c.
References and notes
1. Geissmann, F.; Jung, S.; Littman, D. R. Immunity 2003, 19, 71.
2. Gordon, S.; Taylor, P. R. Nat. Rev. Immunol. 2005, 5, 953.
3. Charo, I. F.; Ransohoff, R. M. N. Engl. J. Med. 2006, 354, 610.
4. Feria, M.; Díaz-González, F. Exp. Opin. Ther. Patents 2006, 16, 49.
5. Dawson, J.; Miltz, W.; Mir, A. K.; Wiessner, C. Exp. Opin. Ther. Targets 2003, 7, 35.
21. Carter, P. H.; Tebben, A. J. Methods Enzymol. 2009, 461, 249.
22. Carter, P. H.; Duncia, J. V.; Mudryk, B. M.; Randazzo, M. E.; Xiao, Z.; Yang, M. G.;
Zhao, R. PCT Int. Appl. WO 2008/014360, 2008.