Camphor sulfonamide derivatives as novel, potent and selective CXCR3 antagonists

Article abstract of DOI:10.1016/j.bmcl.2008.11.008

A series of N-arylpiperazine camphor sulfonamides was discovered as novel CXCR3 antagonists. The synthesis, structure-activity relationships, and optimization of the initial hit that resulted in the identification of potent and selective CXCR3 antagonists are described.

Full text of DOI:10.1016/j.bmcl.2008.11.008

Bioorganic & Medicinal Chemistry Letters 19 (2009) 114–118
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Camphor sulfonamide derivatives as novel, potent and selective
CXCR3 antagonists
c
b
a
b
c,
Yonghui Wang a, , Jakob Busch-Petersen , Feng Wang , Terence J. Kiesow , Todd L. Graybill , Jian Jin
Zheng Yang b, James J. Foley c, Gerald E. Hunsberger c, Dulcie B. Schmidt c, Henry M. Sarau c,
Elizabeth A. Capper-Spudich c,à, Zining Wu b, Laura S. Fisher b,§, Michael S. McQueney c,
Ralph A. Rivero a, Katherine L. Widdowson a
,
*
a Center of Excellence for Drug Discovery, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, PA 19426, USA
b Molecular Discovery Research, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, PA 19426, USA
c Center of Excellence for Drug Discovery, GlaxoSmithKline, 709 Swedeland Road, King of Prussia, PA 19406, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of N-arylpiperazine camphor sulfonamides was discovered as novel CXCR3 antagonists. The syn-
thesis, structure–activity relationships, and optimization of the initial hit that resulted in the identifica-
tion of potent and selective CXCR3 antagonists are described.
Received 9 September 2008
Revised 28 October 2008
Accepted 3 November 2008
Available online 6 November 2008
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords:
Camphor sulfonamides
N-arylpiperazine
CXCR3 receptor antagonists
Chemokine
GPCRs
Inflammation
CXCR3 is a chemokine receptor belonging to the superfamily of
seven transmembrane spanning G-protein-coupled receptors
(GPCRs) and is primarily expressed on activated T-cells with a
Th1 phenotype.1,2 CXCR3 binds to three natural chemokine ligands,
Mig (CXCL9), IP-10 (CXCL10) and I-TAC (CXCL11), which are
believed to play a key role in directing activated T-cells to the sites
of inflammation. Blockade of CXCR3 activation may provide poten-
tial therapeutic benefits in the treatment of inflammatory diseases.
Studies in animal models and human patients have suggested a
role for CXCR3 in multiple sclerosis,3 arthritis,4 IBD,5 asthma,6
COPD7 and transplant rejection.8 As such, CXCR3 has become an
attractive target for the development of anti-inflammatory agents.
Several small molecule CXCR3 antagonists have been reported in
the literature.9,10 Herein, we describe the identification, synthesis,
structure–activity relationships (SARs), selectivity, animal ortholog
activity and some development properties of a novel series of cam-
phor sulfonamides as CXCR3 antagonists.
High throughput screening (HTS) of our compound collection
using a fluorometric imaging plate reader (FLIPR) assay (which mea-
sures inhibition of hIP-10 induced Ca2+ flux in CHO cells expressing
human recombinant CXCR3 receptor)11 led to the identification of
O
O
diamine
S
N
* Corresponding author at present address: Medicinal Chemistry, R&D China,
GlaxoSmithKline, 898 Halei Road, Shanghai 201203, China. Tel.: +1 86 21
61590761; fax: 1 86 21 61590730.
O
N
LHS aryl
RHS camphor
N
E-mail address: yonghui.2.wang@gsk.com (Y. Wang).
F3C
Present address: Center for Integrative Chemical Biology and Drug Discovery,
Division of Medicinal Chemistry & Natural Products, Eshelman School of Pharmacy,
The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
HTS hit, 1a
hCXCR3 pIC50 = 6.6
à
Present address: Department of Biosciences & Biotechnology, Drexel University,
Philadelphia, PA 19104, USA.
§
Present address: 1514 Kirtley Dr., Brandon, FL 33511, USA.
Figure 1. Structure of HTS hit 1a.
0960-894X/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2008.11.008

Y. Wang et al. / Bioorg. Med. Chem. Lett. 19 (2009) 114–118
115
R1
camphor) of this chemical series, a general synthetic route was
developed (Scheme 1).12 Aryl halides (X = Cl or F) 2 were treated
with Boc-protected diamines 3 to produce Boc-protected N-aryldi-
amines, which upon deprotection led to N-aryldiamines 4.13 Sulf-
onylation of 4 with (1S,4R)-camphor-derived sulfonylchlorides
such as 6 afforded N-aryldiamine sulfonamides 5. In an alternative
route to make 5, Boc-protected diamines 3 were reacted with
(1S,4R)-camphor-derived sulfonylchloride 6 to give sulfonamides
7 after deprotection.13 Nucleophilic aromatic substitution of 7 with
aryl halides 2 yielded N-aryldiamine sulfonamides 5.
Various reactions at the carbonyl group on the camphor portion
of 5 led to a series of camphor-derived analogs illustrated in
Scheme 2. Ketones 5 underwent reduction to produce alcohols 8,
which upon treatment with DAST provided fluorides 9. Grignard
addition to 5 formed tertiary alcohols 1014 and ketal formation
produced compounds 11. Wolff–Kishner reduction of ketones 5
under microwave conditions produced saturated analogs 12.15
Reaction of ketones 5 with hydroxyamine produced ketone oximes,
which upon reduction yielded primary amines 13, which in turn
underwent amide formation, sulfonylation, urea formation, and
reductive alkylation to afford amides 14, sulfonamides 15, ureas
16 and secondary amines 17, respectively.
Boc
N
X
Ar
+
HN
3
2
3
+
a, b
O
O
R1
S
Cl
NH
O
N
Ar
6
4
d, b
c
O
O
O
O
R1
R1
S
S
e
N
N
O
O
HN
N
Ar
7
5
Scheme 1. Reagents and conditions: (a) K2CO3, TBAI, DMSO or DIEA, DMSO, heat;
(b) 20% TFA in DCM, rt; (c) (1S,2R)-camphor-derived sulfonylchloride (6), DIEA,
DCM, rt.; (d) DIEA, DCM, rt; (e) Ar-X (2), DIEA, DMSO, heat.
We first explored the LHS aryl moiety in the hit 1a while keep-
ing the camphor moiety and diamine constant (Table 1). It was
observed that the position and nature of a substituent on the
2-pyridinyl ring is important for CXCR3 potency. Repositioning
the trifluoromethyl group from the 5-position (1a) to the 3-, 4-
or 6-position (5a–5c) on the 2-pyridinyl ring led to a dramatic
decline in CXCR3 potency. Replacing the trifluoromethyl with a
bromo substituent reduced CXCR3 potency (5d) while other
1a as a CXCR3 antagonist hit with a pIC50 of 6.6 (Fig. 1). This FLIPR
assay was later used as the primary assay to support SAR work.
In order to explore the SAR around the three key regions (left-
hand side (LHS) aryl, central diamine and right-hand side (RHS)
O
O
O
O
O
O
R1
R1
R1
S
S
S
N
N
N
O
OH
O
N
N
OH
N
Ar
Ar
Ar
Ar
Ar
11
10
5
8
b
d
a
c
O
O
O
O
R1
R1
S
S
N
N
e
N
N
F
Ar
12
9
f, g
O
O
R1
O
O
R1
S
S
N
N
O
NH
N
i
O
NH
S
N
h
O
Ar
R
O
O
R1
R
15
S
14
N
j
k
NH2
N
O
N
O
R1
Ar
O
O
R1
S
S
13
N
NH
N
O
NH
R
N
Ar
Ar
R
H
N
17
16
Scheme 2. Reagents and conditions: (a) NaBH4, EtOH, rt; (b) DAST, DCM, rt; (c) MeMgBr, THF, rt; (d) (CH2)2(OH)2, toluene, reflux; (e) NH2NH2ÁH2O, bis(ethylene glycol),
K2CO3, microwave, 200 °C; (f) NH2OHÁHCl, TEA, EtOH, reflux; (g) NH4OAc, NaCNBH3, TiCl3 (15% in HCl), 0 °C to rt; (h) RCOCl, PS-DIEA, DCM, rt; (i) RSO2Cl, DIEA, DCM, rt; (j)
RNCO, THF, rt; (k) RCHO, MP-borohydride, THF, rt.

116
Y. Wang et al. / Bioorg. Med. Chem. Lett. 19 (2009) 114–118
Table 1
Table 2
SAR of LHS aryl moiety
SAR of the diamine moiety
O
O
3
Q
S
Z
S
N
N
O
O
N
O
X
O
N
Y
Ar
F3C
N
Z
Compound Ar
hCXCR3 pIC50(FLIPR)a
Compound
hCXCR3 pIC50 (FLIPR)a
Q
N
1a
5a
5b
5c
5d
5e
5f
5-(Trifluoromethyl)-2-pyridinyl
3-(Trifluoromethyl)-2-pyridinyl
4-(Trifluoromethyl)-2-pyridinyl
6-(Trifluoromethyl)-2-pyridinyl
5-Bromo-2-pyridinyl
6.6
<4.5
4.6
4.6
5.8
<4.5
<4.5
<4.5
<4.5
<4.5
5.5
6.8
6.4
6.6
6.5
<4.5
5.7
6.5
6.2
5.3
N
X
Y
N
1a
5A
5B
5C
6.6
6.5
6.2
5.2
2-Pyridinyl
N
5-Methyl-2-pyridinyl
5-Nitro-2-pyridinyl
5-Cyano-2-pyridinyl
5-Acetyl-2-pyridinyl
5g
5h
5i
5j
5k
5l
5m
5n
5o
5p
5q
5r
5s
5t
N
N
N
N
3-Nitro-5-(trifluoromethyl)-2-Pyridinyl
3-Fluoro-5-(trifluoromethyl)-2-pyridinyl
3-Chloro-5-(trifluoromethyl)-2-pyridinyl
6-Chloro-5-(trifluoromethyl)-2-pyridinyl
3,6-Dichloro-5-(trifluoromethyl)-2-pyridinyl
4-(Trifluoromethyl)phenyl
2-Fluoro-4-(trifluoromethyl)phenyl
5-(Trifluoromethyl)-2-pyrimidinyl
5-Bromo-2-pyrimidinyl
N
N
N
N
N
6-(Trifluoromethyl)-3-pyridazinyl
3-Isoquinolinyl
4.8
<4.9
5u
1,3-Benzothiazol-2-yl
N
5D
5E
<4.5
6.8
a
The FLIPR results are expressed as a mean of two or more individual experi-
ments; pIC50 was calculated from IC50 using formula, pIC50 = Àlog (IC50).
N
replacements such as a hydrogen, methyl, nitro, cyano, or acetyl at
the 5-position of the 2-pyridinyl ring produced inactive analogs
(5e–5i). With a trifluoromethyl group at the 5-position, additional
substituents at the 3- and/or 6-position of the 2-pyridinyl ring
were well tolerated (5j–5n). For example, compound 5k with a
3-fluoro-5-(trifluoromethyl)-2-pyridinyl LHS provided a CXCR3
pIC50 of 6.8. Replacement of the pyridine ring with a phenyl ring
resulted in a decrease in CXCR3 activity of at least one log unit
(compare 5o to 1a and 5p to 5k). CXCR3 potency was maintained,
however, when the pyridine ring was replaced with a pyrimidine
ring (compare 5q to 1a and 5r to 5d) but decreased when replaced
with a pyridazine ring (5s vs 1a). Other heteroaryl analogs, such as
5t and 5u, showed little CXCR3 activity.
We next explored the central diamine region of the hit 1a while
keeping the camphor moiety and LHS aryl constant (Table 2). A
methyl group on the piperazine ring was found to be tolerated
with a slight improvement in potency when the methyl group
was at the 3-position (5A) rather than the 2-position (5B).16 Install-
ing two methyl groups at the 2- and 5-positions of the piperazine
ring (5C)16 attenuated CXCR3 potency and introducing a methy-
lene bridge (5D) completely abolished CXCR3 potency.
When examining optically pure methyl piperazines, we found
that the 3-(S)-methyl analog (5E) was more potent than the
3-(R)-methyl analog (5F). Increasing the size of the substituent
on the piperazine ring decreased the CXCR3 potency. While 3-ethyl
(5G) and 3-hydroxymethyl (5H) maintained CXCR3 potency, the
more hindered 3-isopropyl (5I) and 3-phenyl (5J) analogs abol-
ished the CXCR3 potency.16 Compared to piperazine, a homopiper-
azine (5K) decreased CXCR3 potency. Other cyclic diamines
(5L and 5M) and an acyclic diamine (5N) showed little CXCR3
activity.
5F
6.3
6.2
N
5G
N
N
HO
5H
5I
6.4
N
N
<4.5
N
N
Ph
5J
<4.5
N
N
N
5K
5L
5.2
4.5
N
N
N
H
H
N
5M
4.8
N
N
N
The camphor portion of the hit 1a was subsequently explored
(Table 3). Stereochemistry of the camphor plays an important role
in CXCR3 potency. The S-isomer 1a [(1S,4R)-7,7-dimethyl-bicy-
clo[2.2.1]heptan-2-one] was found to be more potent than the
5N
<4.5
a
The FLIPR results are expressed as a mean of two or more individual experi-
ments; pIC50 was calculated from IC50 using formula, pIC50 = Àlog (IC50).

Y. Wang et al. / Bioorg. Med. Chem. Lett. 19 (2009) 114–118
117
Table 3
Table 4
SAR of the camphor-derived moiety
Data of some combination compounds
R
R2
S
N
N
O
R4
N
O
S
R3
N
N
O
F3C
N
O
F3C
X
Compound
hCXCR3 pIC50 (FLIPR)a
R1
R
Compound
X
R1 R2
R3/R4
hCXCR3 pIC50 mCXCR3 pIC50
(FLIPR)a
(FLIPR)a
1a
6.6
1a
5k
5E
C
C
C
C
C
C
C
C
C
C
C
C
C
N
H
F
H
F
F
F
H
H
H
F
F
F
H
H
@O
@O
@O
@O
@O
6.6
6.8
6.8
7.1
6.3
6.5
6.8
7.5
6.5
7.3
7.5
7.2
5.9
6.1
5.6
6.3
–
5.2
6.2
6.7
6.2
6.8
6.7
5.8
5.8
6.0
O
(S)AMe
(S)AMe
(R)AMe
O
18a
18b
18c
18d
18e
18f
18g
18h
18i
18j
18k
1b
5.8
6.8
6.1
6.7
6.7
6.1
6.1
5.7
6.2
6.1
(S)ACH2OH @O
(S)AMe
(S)AMe
(S)AMe
(S)AMe
(S)AMe
(S)AMe
(S)AMe
(S)AMe
( )AOH
(S)AOH
(R)AOH
( )AOH
(S)AOH
(R)AOH
8a
HO
F
F
—
AOC2H5OA 7.4
@O 6.9
a
9a
The FLIPR results are expressed as a mean of two or more individual experi-
ments; pIC50 was calculated from IC50 using formula, pIC50 = Àlog (IC50).
tertiary alcohol 10a and the cyclic ketal 11a maintained CXCR3
potency while derivatives with smaller substituents such as fluo-
rine (9a)17 or hydrogen (12a) decreased CXCR3 potency. The amine
13a17 and its derivatives (14aÀ17a)17 showed lower CXCR3
potency.
10a
11a
12a
13a
14a
15a
16a
HO
O
Having explored the three regions in the hit 1a and identified
the potency-improving moieties in each region, some combination
compounds which incorporated the best substituents in each area
were prepared (Table 4). It is worth noting that for (1S,4R)-cam-
phor alcohols, two diastereomers were isolated from each initial
mixture (e.g., 18e and 18f from 18d, 18h and 18i from 18g).18
The S-isomer [(1S,2S,4R)-7,7-dimethyl-bicyclo[2.2.1]heptan-2-ol]
was generally found to be more potent than the R-isomer
[(1S,2R,4R)-7,7-dimethyl-bicyclo[2.2.1]heptan-2-ol]. As shown in
Table 4, in most cases an improvement in CXCR3 potency was ob-
served when combining potency-enhancing groups identified from
each region. For example, compound 18a with both a 3-fluoro on
the pyridine ring (5k, pIC50 = 6.8) and a (S)-3-methyl on the piper-
azine ring (5E, pIC50 = 6.8) showed a CXCR3 FLIPR pIC50 of 7.1.
Compound 18h with a 3-fluoro on the pyridine ring, a (S)-3-methyl
on the piperazine ring and a (S)-2-hydroxyl on the camphor moiety
showed a CXCR3 FLIPR pIC50 of 7.5.
The compounds in this series were found to be reversible CXCR3
antagonists that are competitive with hIP-10. For example, com-
pounds 1a, 18a and 18h showed CXCR3 FLIPR pA2 values of 6.9,
7.6 and 7.7, respectively.19 Some camphor sulfonamides were also
tested in a mouse CXCR3 FLIPR assay20 and found to be active but
with lower potency as compared to human CXCR3 (Table 4). For
example, compounds 1a, 18a and 18h showed mouse CXCR3 FLIPR
pIC50s of 5.9, 6.3 and 6.7, respectively.
O
H2N
O
N
H
O
O
S
N
H
O
N
N
H
H
17a
5.1
Key compounds in the series were evaluated in selectivity,
hERG, CYP450 inhibition, and in vivo PK studies. With regards to
selectivity, compound 18a, for example, was found to be highly
selective in a CEREP screen of 50 receptors, transporters and ion
N
H
a
The FLIPR results are expressed as a mean of two or more individual experi-
ments; pIC50 was calculated from IC50 using formula, pIC50 = Àlog (IC50).
channels (<23% of inhibition at 1 lM against all 50 targets in the
panel) and showed at least 100-fold selectivity versus a number
of 7TM receptors including chemokine receptors (5HT1A, 5HT1B,
5HT1D, 5HT2A, 5HT2C, 5HT6, 5HT7, H1, H3, Adrenergic Alpha
1A, Adrenergic Alpha 1B, Adrenergic Beta 2, Adenosine A1, Adeno-
sine A2a, D2, D3, CXCR2, CXCR4, CXCR1). Compound 18a did not
R-isomer 1b [(1R,4R)-7,7-dimethyl-bicyclo[2.2.1]heptan-2-one]. In
general, the derivatives obtained from modification of the ketones
1a and 1b were well tolerated. Alcohol 8a17 was found to be
slightly more potent than its corresponding ketone (1a). The

118
Y. Wang et al. / Bioorg. Med. Chem. Lett. 19 (2009) 114–118
L.; Meissner, J. W. G.; Owen, D. A.; Thomas, E. J. Bioorg. Med. Chem. Lett. 2007,
show a hERG liability (binding IC50 > 63 lM). In a CYP450 screen,
17, 6806; (f) Watson, R. J.; Allen, D. R.; Birch, H. L.; Chapman, G. A.; Galvin, F. C.;
Jopling, L. A.; Knight, R. L.; Meier, D.; Oliver, K.; Meissner, J. W. G.; Owen, D. A.;
Thomas, E. J.; Tremayne, N.; Williams, S. C. Bioorg. Med. Chem. Lett. 2008, 18,
147; (g) Du, X.; Chen, X.; Mihalic, J. T.; Deignan, J.; Duquette, J.; Li, A.-R.; Lemon,
B.; Ma, J.; Miao, S.; Ebsworth, K.; Sullivan, T. J.; Tonn, G.; Collins, T. L.; Medina, J.
C. Bioorg. Med. Chem. Lett. 2008, 18, 608; (h) Knight, R. L.; Allen, D. R.; Birch, H.
L.; Chapman, G. A.; Galvin, F. C.; Jopling, L. A.; Lock, C. J.; Meissner, J. W. G.;
Owen, D. A.; Raphy, G.; Watson, R. J.; Williams, S. C. Bioorg. Med. Chem. Lett.
2008, 18, 629; (i) Li, A.-R.; Johnson, M. G.; Liu, J.; Chen, X.; Du, X.; Mihalic, J. T.;
Deignan, J.; Gustin, D. J.; Duquette, J.; Fu, Z.; Zhu, L.; Marcus, A. P.; Bergeron, P.;
McGee, L. R.; Danao, J.; Lemon, B.; Carabeo, T.; Sullivan, T.; Ma, J.; Tang, L.; Tonn,
G.; Collins, T. L.; Medina, J. C. Bioorg. Med. Chem. Lett. 2008, 18, 688; (j) Hayes,
M. E.; Wallace, G. A.; Grongsaard, P.; Bischoff, A.; George, D. M.; Miao, W.;
McPherson, M. J.; Stoffel, R. H.; Green, D. W.; Roth, G. P. Bioorg. Med. Chem. Lett.
2008, 18, 1573.
the ketone 18a showed some inhibition for two major P450
isozymes [IC50 = 0.16 M for 1A2 and 0.32 M for 3A4 (red)]. How-
ever, little 1A2 and 3A4 inhibition was observed for the more
potent alcohol analog 18h [IC50s: 1A2, > 25 M; 2C9, 4.0 M;
2C19, 4.0 M; 2D6, > 25 M; 3A4(red), > 25 M; 3A4(green),
13.6 M]. The compounds in the series generally exhibited good
artificial membrane permeability (e.g., 352 nm/s for 18a) but low
aqueous solubility (e.g., 0.004 mg/mL for 18a) unless a polar group
was introduced to the molecule. For example, the compound with
(S)-3-hydroxymethyl group on the piperazine ring (18c) had a sol-
ubility of 0.04 mg/mL and permeability of 560 nm/s. The pharma-
cokinetic properties for compound 18a were determined in rat,
dosed 1.1 mg/kg iv and 2.0 mg/kg po. This compound demon-
strated high clearance (Clb = 108 mL/min/kg) with a half-life of
0.5 h, volume of distribution (Vdss) of 2.2 L/kg and oral bioavail-
ability (F) of 8%. The preliminary developability data suggest that
this series constitutes a reasonable starting point for further lead
optimization.
l
l
l
l
l
l
l
l
10. For a recent review on small-molecule CXCR3 ligands, see: Wijtmans, M.;
Verzijl, D.; Leurs, R.; de Esch, I. J. P.; Smit, M. J. ChemMedChem 2008, 3, 861.
11. Functional studies (IP-10 induced Ca2+ flux) were performed on a CHO-K1
(Chinese hamster ovary) cell line stably expressing CXCR3 and
Ga16
(Euroscreen, Brussels, Belgium). Cells were plated and grown for 24 h in 96-
well, black wall, clear bottom plates (Packard View). On day of assay, cells were
loaded with fluoro-4-acetoxymethyl ester fluorescent indicator dye (Fluoro-4
AM, from Molecular Probes) and treated for 10 min at 37 °C with
a
concentration range of compound (0.01–33 M). Plates were placed onto
l
FLIPR (Fluorometric Imaging Plate Reader, Molecular Devices, Sunnyvale, CA)
for analysis. The percent of maximal human IP-10 induced Ca2+ mobilization
induced by 33 nM IP-10, an EC80 concentration against CXCR3, was determined
after treatment of cells with each concentration of compound. The IC50 values
were calculated as the concentration of test compound that inhibits 50% of the
maximal response induced by IP-10. The FLIPR results are expressed as a mean
of two or more individual experiments.
In summary, exploration of a novel series of camphor sulfona-
mides identified via HTS led to the discovery of hIP-10 competitive
and reversible CXCR3 antagonists such as 18a and 18h with excel-
lent functional activity, cross-species activity and selectivity. The
further optimization of this series (e.g., camphor replacement) to
improve PK will be the subject of future publications.
12. For synthesis and compound characterization, see: Busch-Petersen, J.; Jin, J.;
Graybill, T. L.; Kiesow, T. J.; Rivero, R. A.; Wang, F.; Wang, Y. Chem. Abstr. 2007,
147, 143569. WO 2007076318A2, 2007.
13. All substituted piperazines used for synthesis were racemic unless stated
otherwise. Unprotected diamines were used if the reacting amino site was less
hindered (more reactive) compared to the other amino site.
Acknowledgments
We thank Minghui Wang for NMR, Manon S. Villeneuve for chi-
ral HPLC separation and Doug J. Minick for VCD analysis.
14. Aggarwal, V. K.; Charmant, J.; Dudin, L.; Porcelloni, M.; Richardson, J. PNAS
2004, 101, 5467.
15. The methyl Grignard addition to 5 formed the tertiary alcohol 10 as a single
diastereomer.
References and notes
16. Compounds 5A–C (trans-2,5-dimethyl piperazine was used for the preparation
of 5C) and 5G–J were tested as a 1:1 mixtures of diastereomers.
17. Camphor alcohols 8a, 18d, 18g were prepared and tested as mixtures of
diastereomers with ratios of ꢀ5.6:1 favoring the R-isomer (determined by 1H
NMR); Compound 9a was prepared from the corresponding alcohol 8a, so the
ratio of the two diastereomes of 9a was estimated to be ꢀ1:5.6 favoring the S-
1. Medina, J.; Johnson, M. G.; Collins, T. L. Ann. Rep. Med. Chem. 2005, 40, 215.
2. Collins, T. L.; Johnson, M. G.; Medina, J. C.. In Chemokine Biology-Basic Research
and Clinical Application; Neote, K., Letts, G. L., Moser, B., Eds.; Birkhauser Verlag
Publishers: Berlin, 2007; Vol. 2, p 79.
3. (a) Goldberg, S. H.; van der Meer, P.; Hesselgesser, J.; Jaffer, S.; Kolson, D. L.;
Albright, A. V.; Golzalez- Scarano, F.; Lavi, E. Neuropathol. Appl. Neurobiol. 2001,
27, 127; (b) Szczucinski, A.; Losy, J. Acta Neurol. Scand. 2007, 115, 137.
4. (a) Tsubaki, T.; Takegawa, S.; Hanamoto, H.; Arita, N.; Kamogawa, J.;
Yamamoto, H.; Takubo, N.; Nakata, S. Clin. Exp. Immunol. 2005, 141, 363; (b)
Norii, M.; Yamamura, M.; Iwahashi, M.; Ueno, A.; Yamana, J.; Makino, H. Acta
Med. Okayama 2006, 60, 149.
isomer, assuming
a complete inversion of configuration in a simple SN2
reaction; Compounds 13a–17a were tested as mixtures of diastereomers with
ratios of ꢀ2.6:1, favoring the R-isomer. The individual diastereomers were not
isolated and characterized except for 18d and 18g (see Ref. 18).
18. (a) Chiral HPLC was employed to separate two diastereomers from each
mixture of camphor alcohols (conditions for separating 18e and 18f from 18d:
Agilent OA LC using Phenomenex Luna eluting with 50–90% CH3CN in H2O with
0.1% FTA; SFC conditions for separating 18h and 18i from 18g: 30 mm AD, 140
bar, 40 °C, 75 g/min CO2, 13 mL/min MeOH, UV @ 250 nm); (b) Stereochemistry
of 18e, 18f, 18h and 18i was assigned by Vibrational Circular Dichroism (VCD)
analysis.
5. Singh, U. P.; Venkataraman, C.; Singh, R.; Lillard, J. W. Endocrinol. Metab.
Immune Disord. Drug Targets 2007, 7, 111.
6. Bradding, P.; Walls, A. F.; Holgate, S. T. J. Allergy Clin. Immunol. 2006, 117, 1277.
7. Donnelly, L. E.; Barnes, P. J. Trends Pharmacol. Sci. 2006, 27, 546.
8. (a) Mazzinghi, B.; Netti, G. S.; Lazzeri, E.; Romagnani, P. G. Ital. Nefrol. 2007, 24,
212; (b) Hancock, W. W.; Lu, B.; Gao, W.; Csizmadia, V.; Faia, K.; King, J. A.;
Smiley, S. T.; Ling, M.; Gerard, N. P.; Gerard, C. J. Exp. Med. 2000, 192, 1515; (c)
Akashi, S.; Sho, M.; Kashikuza, K.; Hamada, K.; Ikeda, N.; Kuzumoto, Y.; Tsurui,
Y.; Nomi, T.; Mizuno, T.; Kanehiro, H.; Hisanaga, M.; Ko, S.; Nakajima, Y.
Transplantation 2005, 80, 378.
9. (a) Storelli, S.; Verdijk, P.; Verzijl, D.; Timmerman, H.; van de Stolpe, A. C.;
Tensen, C. P.; Smit, M. J.; De Esch, I. J. P.; Leurs, R. Bioorg. Med. Chem. Lett. 2005,
15, 2910; (b) Cole, A. G.; Stroke, I. L.; Brescia, M.-R.; Simhadri, S.; Zhang, J. J.;
Hussain, Z.; Snider, M.; Haskell, C.; Ribeiro, S.; Appell, K. C.; Henderson, I.;
Webb, M. L. Bioorg. Med. Chem. Lett. 2006, 16, 200; (c) Allen, D. R.; Bolt, A.;
Chapman, G. A.; Knight, R. L.; Meissner, J. W. G.; Owen, D. A.; Watson, R. J.
Bioorg. Med. Chem. Lett. 2007, 17, 697; (d) Johnson, M.; Li, A.-R.; Liu, J.; Fu, Z.;
Zhu, L.; Miao, S.; Wang, X.; Xu, Q.; Huang, A.; Matcus, A.; Xu, F.; Ebsworth, K.;
Sablan, E.; Danao, J.; Kumer, J.; Dairaghi, D.; Lawrence, C.; Sullivan, T.; Tonn, G.;
Schall, T.; Collins, T.; Medina, J. Bioorg. Med. Chem. Lett. 2007, 17, 3339; (e)
Watson, R. J.; Allen, D. R.; Birch, H. L.; Chapman, G. A.; Hannah, D. R.; Knight, R.
19. Concentration response curves of human IP-10 induced Ca2+ mobilization were
generated in the presence of a single 30 min pre-treated concentration of
antagonist, [B] (1 lM), or vehicle alone. The EC50, the concentration of human
IP-10 to elicit 50% of the maximal response induced by human IP-10 for a given
treatment condition, was calculated. A dose ratio (DR) was calculated as the
ratio of the EC50 for compound pre-treated human IP-10 curves over the EC50
for vehicle treated human IP-10 curves. pA2 serves as an empirical measure of
potency and is generated for a single concentration of antagonist using the
following formula: pA2 = log(DR-1) À log[B]. The FLIPR results are expressed as
a mean of two or more individual experiments.
20. Human U2OS cells transiently transduced with a mixture of recombinant
BacMan viruses expressing murine CXCR3 receptor and chimeric G-protein
Gqi5, respectively, were used in the studies. IC50 values of each compound
were determined by an inhibition dose-response curve. See, Ames, R. S.;
Fornwald, J. A.; Nuthulaganti, P.; Trill, J. J.; Foley, J. J.; Buckley, P. T.; Kost, T. A.;
Wu, Z.; Romanos, M. A. Receptors Channels 2004, 10, 99.