Synthesis and biological evaluation of linear phenylethynylbenzenesulfonamide regioisomers as cyclooxygenase-1/-2 (COX-1/-2) inhibitors

Article abstract of DOI:10.1016/j.bmc.2006.03.050

A group of regioisomeric phenylethynylbenzenesulfonamides possessing a COX-2 SO₂NH₂ pharmacophore at the para-, meta- or ortho-position of the C-1 phenyl ring, in conjunction with a C-2 substituted-phenyl (H, OMe, OH, Me, F) group, w

Full text of DOI:10.1016/j.bmc.2006.03.050

Bioorganic & Medicinal Chemistry 14 (2006) 5259–5265
Synthesis and biological evaluation of linear
phenylethynylbenzenesulfonamide regioisomers as
cyclooxygenase-1/-2 (COX-1/-2) inhibitors
a
b
b
b,
*
Raymond Anana, P. N. Praveen Rao, Qiao-Hong Chen and Edward E. Knaus
a
Lakeland College, Lloydminister, Alta., Canada S9V 1Z3
Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alta., Canada T6G 2N8
b
Received 27 February 2006; revised 21 March 2006; accepted 29 March 2006
Available online 25 April 2006
2 2
Abstract—A group of regioisomeric phenylethynylbenzenesulfonamides possessing a COX-2 SO NH pharmacophore at the para-,
meta- or ortho-position of the C-1 phenyl ring, in conjunction with a C-2 substituted-phenyl (H, OMe, OH, Me, F) group, were
synthesized and evaluated as inhibitors of the cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) isozymes. The target
1
,2-diphenylacetylenes were synthesized via a palladium-catalyzed Sonogashira cross-coupling reaction. In vitro COX-1/-2 isozyme
inhibition structure–activity data showed that COX-1/-2 inhibition and the COX selectivity index (SI) are sensitive to the regioiso-
meric placement of the COX-2 SO NH pharmacophore where the COX-2 potency order for the benzenesulfonamide regioisomers
was generally meta > para and ortho. Among this group of compounds, the in vitro COX-1/-2 isozyme inhibition studies identified
-(2-phenylethynyl)benzenesulfonamide (10a) as a COX-2 inhibitor (COX-2 IC50 = 0.45 lM) with a good COX-2 selectivity (COX-2
SI = 70). In contrast, 2-[2-(3-fluorophenyl)ethynyl]benzenesulfonamide (11c) possessing a SO NH COX-2 pharmacophore at the
2
2
3
2
2
ortho-position of the C-1 phenyl ring exhibited COX-1 inhibition and selectivity (COX-1 IC50 = 3.6 lM). A molecular modeling
study where 10a was docked in the binding site of COX-2 shows that the meta-SO NH COX-2 pharmacophore was inserted inside
2
2
the COX-2 secondary pocket (Arg513, Phe518, Val523, and His90). Similar docking of 10a within the COX-1 binding site shows
that the meta-SO NH pharmacophore is unable to interact with the respective amino acid residues in COX-1 that correspond
to those near the secondary pocket in COX-2 due to the presence of the larger Ile523 in COX-1 that replaces Val523 in COX-2.
2
2
Ó 2006 Elsevier Ltd. All rights reserved.
1. Introduction
was discovered that is now called cyclooxygenase-2
4
(
COX-2). This discovery provided the rationale for
The discovery of the mechanism of action of aspirin and
indomethacin in the late 1970s was a critical event in the
development of nonsteroidal anti-inflammatory drugs
development of selective COX-2 inhibitors that would
be effective anti-inflammatory agents with a reduced side
effect profile. Several classes of selective COX-2 inhibi-
tors referred to as diarylheterocylces possess vicinal aryl
rings attached to a central heterocyclic ring scaffold. In
this regard, celecoxib (1) having a central five-membered
pyrazole ring, and rofecoxib (2) having a central five-
membered 2(5H)-furanone ring, were the first two
1
(
NSAIDs). Classical NSAIDs such as aspirin, ibupro-
fen, and indomethacin produce their beneficial anti-in-
flammatory activity by inhibition of cyclooxygenase
(COX)-derived prostaglandin (PG) synthesis. However,
a major drawback of NSAID therapy is the develop-
5
,6
ment of adverse side effects such as gastrointestinal
2
COX-2 inhibitors approved for clinical use (Fig. 1).
(
GI toxicity has been attributed to the inhibition of cyto-
GI) toxicities that arise during their chronic use. This
Extensive structure–activity relationship (SAR) studies
for the diarylheterocycle class of compounds have
shown that a SO NH , or a SO Me, substituent at the
3
protective PGs produced via the COX pathway. In the
early 1990s, an inducible isoform of the COX enzyme
2
2
2
para-position of one of the aryl rings is a requirement
7
for optimum COX-2 selectivity and potency. However,
Keywords: Phenylethynylbenzenesulfonamides; Cyclooxygenase-1/2
inhibitors; COX-2 pharmacophore; Anti-inflammatory and analgesic
activity.
the selective COX-2 inhibitors rofecoxib and valdecoxib
were recently withdrawn from the market due to adverse
cardiovascular side effects associated with their pro-
*
Corresponding author. Tel.: +1 780 492 5993; fax: +1 780 492
217; e-mail: eknaus@pharmacy.ualberta.ca
8
1
longed use. Consequently, there is a current need to
0
968-0896/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2006.03.050

5260
R. Anana et al. / Bioorg. Med. Chem. 14 (2006) 5259–5265
SO2NH2
R
SO2Me
3
R2
2
R1
C
C
H
+
4
SO2NH2
N
N
F3C
O
8a, R2 = 2-I
7
2
O
8b, R = 3-Br
Me
c, R2 = 4-Br
8
a
Celecoxib (1)
Rofecoxib (2)
MeO S
R
MeO2S
2
o-
m-
SO NH
p-
2
2
R1
C
C
H
9
9
9
, para-SO NH
10, meta-SO NH
11, ortho-SO NH
2 2
2
2
2
2
n-Alkyl
n-Hexyl
a, R = H, R1 = H
b, R = H, R1 = Me
10a, R = H, R1 = H
10b, R = H, R1 = Me
11a, R = H, R1 = H
11b, R = H, R1 = Me
9c, R = OMe, R1 = H
9d, R = OH, R1 = H
9e, R = F, R1 = H
10c, R = OMe, R1 = H 11c, R = F, R1 = H
10d, R = F, R1 = H
(
3)
(4)
C
o- m-
R1
p-
MeO S
C
C
C
O
R1
C
2
Scheme 1. Reagents and conditions: (a) Pd(PPh ) Cl , CuI, Et N,
3
3
2
2
R1 = 3,4-disubstituted-phenyl
R1 = SO Me
THF, reflux 16 h, or 50 °C for 5 h.
2
(5)
(6)
Figure 1. Some representative selective cyclooxygenase-2 (COX-2)
inhibitors.
presence of an acid acceptor such as triethylamine.
The low reactivity of 2-bromobenzenesulfonamide in
the Sonogashira cross-coupling reaction prompted uti-
lization of the more reactive 2-iodobenzenesulfona-
mide. Accordingly, 2-iodobenzenesulfonamide (8a), a
precursor to the target compounds 11a–c, was pre-
pared by diazotization of commercially available 2-
aminobenzenesulfonic acid (12) that was subsequently
reacted with potassium iodide to afford 2-iodoben-
zenesulfonic acid (14) in 70% yield (see Scheme 2).
Treatment of 2-iodobenzenesulfonic acid (14) with
PCl5 according to the procedure of Chau and Kice
develop safer anti-inflammatory agents based on alter-
native templates. Studies in our drug design program
indicate that acyclic triaryl olefins (3), 1,2-diaryl (E)-ole-
fins (4), and acetylenic ketones (5), lacking a traditional
central heterocyclic or carbocyclic ring template, are po-
tent selective COX-2 inhibitors with clinically relevant
9
–12
anti-inflammatory and analgesic activities.
It has
also been reported that substituted diphenyl compounds
possessing a central linear acetylene moiety are useful
for the treatment of psoriatic dermatitis, epithelial can-
1
6
furnished 2-iodobenzenesulfonyl chloride (15). Sub-
sequent reaction of 2-iodobenzenesulfonyl chloride
1
3
cer, and arthritic diseases. In an earlier investigation,
we demonstrated that substituted-1,2-diphenylacetylene
regioisomers (6) are effective COX-1/-2 inhibitors that
+
1
4
NH2
N
exhibit in vivo anti-inflammatory activities. As a part
of our ongoing program, we now describe the design,
synthesis, in vitro COX-1 and COX-2 inhibitory activi-
ties, and in vivo anti-inflammatory activity for a class
of regioisomeric 1,2-diphenylacetylenes possessing a
SO NH COX-2 pharmacophore at the para-, meta- or
2
Cl
I
(
a)
(b)
SO H
SO H
SO3H
3
3
12
13
14
(c)
2
2
ortho-position of one of the phenyl rings.
I
I
(
d)
2. Chemistry
2
SO NH2
SO Cl
2
8a
15
The 1,2-diphenylacetylene regioisomers (9a–e, 10a–d,
and 11a–c) possessing a SO NH substituent at the
2
2
Br
Br
para-, meta- or ortho-position of the C-1 phenyl ring
were prepared in good yield (52–82%) using a palladi-
um-catalyzed Sonogashira cross-coupling reaction
(
d)
SO Cl
SO NH
2 2
2
1
5
16
8c
(Scheme 1). Phenylacetylene precursors (7) possess-
ing a variety of substituents (R = H, OMe, OH, F;
1
R = H, Me), and either 2-iodobenzenesulfonamide
2 3
Scheme 2. Reagents and conditions: (a) water, Na CO to form a
homogeneous solution, addition of NaNO at 25 °C, and then
2
(
8a), 3-bromobenzenesulfonamide (8b), or 4-bromo-
concentrated HCl at 0 °C; (b) KI, water, warm to 25 °C, and then
heat at reflux until nitrogen evolution ceases; (c) neutralization by
titration with NaOH solution, drying the sodium sulfonate salt, and
benzenesulfonamide (8c), were employed in this
cross-coupling reaction using dichlorobis(triphenyl-
phosphine)palladium(0)/CuI as catalysts in the
5 4
addition of PCl ; (d) concentrated NH OH solution, 25 °C.

R. Anana et al. / Bioorg. Med. Chem. 14 (2006) 5259–5265
5261
1
(
15) with concentrated ammonia solution afforded 8a
(R = F; R = H) exhibited the best combination of
COX-2 inhibitory potency and selectivity (COX-2
IC50 = 0.3 lM; COX-1 IC50 = 3.6 lM; SI = 12), and it
was a superior COX-2 inhibitor compared to the refer-
ence compound rofecoxib (IC50 = 0.5 lM). In compari-
1
7
in near quantitative yield. 4-Bromobenzenesulfona-
mide (8c) was prepared in a similar way by reaction
of commercially available 4-bromobenzenesulfonyl
chloride (16) with concentrated ammonia solution as
illustrated in Scheme 2.
son,
a meta-methoxy substituent (9c, R = OMe;
1
R = H) produced a decrease in both COX-2 inhibitory
potency and selectivity (COX-2 IC50 = 6.9 lM; COX-1
IC50 = 31.6 lM; SI = 5.0). In contrast, compound 9d
3
. Results and discussion
1
having a meta-hydroxy substituent (R = OH; R = H)
Structure–activity relationship data for first generation
COX-2 inhibitors such as celecoxib and rofecoxib identi-
fied the requirement for a SO NH or a SO Me COX-2
pharmacophore with respect to optimum COX-2 inhibi-
7
tory activity and selectivity. Accordingly, a group of
was a 10-fold more potent inhibitor of COX-1 than
COX-2. A C-2 meta-substituted-phenyl ring is required
for COX inhibitory activity since the C-2 phenyl and
2
2
2
1
para-methylphenyl compounds (9a, R = H, R = H; 9b,
R = Me, R = H) were inactive against both COX-1
1
phenylethynylbenzenesulfonamide regioisomers (9–11)
possessing a central linear acetylenic template were
designed such that the COX-2 SO NH pharmacophore
was positioned at the para-, meta- or ortho-position of
the C-1 phenyl ring. In addition, substituents on the C-
and COX-2 (IC50 > 100 lM). The relative COX-2 inhib-
itory potency order for this para-substituted-benzene-
sulfonamide subgroup of compounds 9a–e was 3-
F > 3-OMe ꢀ 3-OH (COX-1 selective) > inactive 4-H,
4-Me.
2
2
2
phenyl ring were varied (R = H, OMe, OH, F;
1
R = H, Me) to determine the effect of positional, steric,
and electronic substituent properties upon COX-1 and
COX-2 inhibitory potency and selectivity. The in vitro
ability of the title compounds to inhibit the COX-1 and
COX-2 isozymes was carried out using an enzyme immu-
no assay (EIA), and the results are listed in Table 1.
Structure–activity data obtained for the benzenesulfona-
mide regioisomers 9–11 indicate that COX-2 inhibitory
potency and selectivity varied considerably based on
the position of the COX-2 SO NH pharmacophore
The in vitro COX-1/-2 inhibitory activity data for com-
pounds 10a–d possessing a SO NH COX-2 pharmaco-
2
2
phore at the meta-position of the C-1 phenyl ring were
highly variable. For example, the meta-sulfonamide
compound 10a (R = R = H), unlike the inactive para-
1
sulfonamide regioisomer (9a), exhibited good COX-2
inhibitory potency and selectivity (COX-2 IC50
=
0.45 lM; COX-1 IC50 = 31.6 lM; SI = 70). Related
compounds having a C-2 para-methylphenyl (10b), or
meta-methoxyphenyl (10c), substituent showed weak
COX-2, but more potent COX-1 inhibitory activities rel-
ative to the C-2 phenyl analog (10a). The presence of a
2
2
and the properties of the C-2 phenyl substituents.
1
Among the subgroup of compounds 9a–e, possessing a
para-SO NH COX-2 pharmacophore, compound 9e
C-2 3-fluorophenyl substituent (10d, R = F, R = H)
maintained COX-2 selectivity (SI > 15), but caused a de-
2
2
Table 1. In vitro COX-1 and COX-2 inhibition data for phenylethynylbenzenesulfonamides (9a–e, 10a–d and 11a–c)
R
R
SO NH2
R
H NO S
2
2
2
R1
SO2NH2 R1
R1
9
a-e
10a-d
1
1a-c
1
R
a
b
Compound
R
IC50 (lM)
COX-2 SI
COX-1
COX-2
9
9
9
9
9
1
1
1
1
1
1
1
a
H
H
>100
>100
31.6
3.1
>100
>100
6.8
N/A
N/A
5
b
H
Me
H
c
OMe
OH
F
d
H
32.6
0.3
—
e
H
3.6
12
70
0a
0b
0c
0d
1a
1b
1c
H
H
31.6
1.0
0.45
3.2
H
Me
H
—
—
OMe
F
1.0
2.0
6.8
H
>100
>100
32.0
3.6
>15
N/A
1
H
H
>100
32.0
>100
2.4
H
Me
H
F
N/A
N/A
472
>200
Aspirin
Celecoxib
Rofecoxib
—
—
—
—
—
—
0.35
33.1
>100
0.07
0.50
a
Values are means of two determinations acquired using an ovine COX-1/COX-2 assay kit (Catalog No. 560101, Cayman Chemicals Inc., Ann
Arbor, MI, USA) and the deviation from the mean is <10% of the mean value.
In vitro COX-2 selectivity index (COX-1 IC50/COX-2 IC50).
b

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R. Anana et al. / Bioorg. Med. Chem. 14 (2006) 5259–5265
crease in COX-2 inhibitory potency (IC50 = 6.8 lM)
compared to the C-2 phenyl compound 10a. Com-
pounds 11a–c having a SO NH COX-2 pharmacophore
center of the unsubstituted C-2 phenyl ring and the
˚
OH of Ser530 is about 5.44 A.
2
2
at the ortho-position of the C-1 phenyl ring were either
inactive (11a, R = R = H; 11c, R = F, R = H) or weak
(
In fact, the C-2 3-fluorophenyl compound 11c was a
weak (IC50 = 3.6 lM), but selective inhibitor of COX-1.
The SO NH and the SO Me pharmacophores present
2
2
2
1
1
in celecoxib and rofecoxib, respectively, are known to
induce COX-2 selectivity by insertion into the secondary
pocket of the COX-2 binding site that is absent in
1
11b, R = H, R = Me) inhibitors of the COX-2 isozyme.
7
COX-1. This additional secondary pocket in COX-2
is formed due to a conformational change at Tyr355
that is attributed to the presence of Ile523 in COX-1 rel-
A molecular modeling (docking) experiment was carried
out to determine the binding interactions of the most
potent and selective COX-2 inhibitor 3-(2-phenylethy-
nyl)benzenesulfonamide (10a, COX-2 IC50 = 0.45 lM;
COX-1 IC50 = 31.6 lM; SI > 70) in the COX-2 binding
site as shown in Figure 2. As per our hypothesis, model-
ing the most stable enzyme–ligand complex shows that
the meta-SO NH COX-2 pharmacophore is oriented
1
8
ative to Val523 having a smaller side chain in COX-2.
Accordingly, it was also of interest to perform a molec-
ular modeling experiment wherein 10a was docked in the
COX-1 binding site (as shown in Fig. 3). The most stable
enzyme–ligand complex shows that the meta-SO NH
2
2
COX-2 pharmacophore is unable to interact with the
amino acid residues in COX-1 that correspond to the
amino acid residues in the vicinity of the COX-2 second-
ary pocket, due to the presence of a larger Ile523 in
COX-1. However, a favorable hydrogen bonding inter-
action was observed between the NH2 (of SO NH )
2
2
in the vicinity of COX-2 secondary pocket where it is
surrounded by amino acids Val523, Phe518, Ile517,
Arg513, and His90. The SO moiety (of SO NH ) is
2
2
2
positioned within van der Waals contact range of amino
˚
acids such as Phe518 and Ile517 (distance < 5 A). The
2
2
˚
and the backbone NH of Ile517 (distance ꢁ 2.39 A).
The benzenesulfonamide ring is oriented toward a
hydrophobic pocket comprised of Leu352, Ile517,
Met522, Ile523, and Gly526. Due to the presence of
the bulkier Ile523 in the COX-1 binding site, the C-2
unsubstituted phenyl ring in 10a is oriented toward the
mouth of the COX-1 binding site closer to amino acid
residues such as Val116, Arg120, and Tyr355. In con-
trast, the C-2 unsubstituted-phenyl ring of 10a assumes
a position in a hydrophobic region toward the apex of
the COX-2 binding site (Fig. 2). This observation
NH (of SO NH ) was oriented toward His90, Thr94
2
2
2
and Tyr355 closer to the mouth of the COX-2 active
site. One of the H-atoms of the NH group undergoes
2
a hydrogen-bonding interaction with the N-atom of
˚
His90 (distance ꢁ 3.57 A). The distance between the sec-
ond H-atom of the NH group and the OH of Tyr355 is
2
˚
about 3.83 A. The linear acetylene scaffold, which is sur-
rounded by Leu352, Gly526, and Ala527, serves to ori-
ent the C-2 unsubstituted phenyl ring toward the apex of
the COX-2 binding site, in a region comprised of
Tyr385, Phe381, Tyr348, Phe205, and Val344
˚
(
distance < 5 A). The interspacial distance between the
Figure 2. Docking of 3-(2-phenylethynyl)benzenesulfonamide (10a)
ball and stick) in the active site of murine COX-2. Hydrogen atoms of
the amino acid residues have been removed to improve clarity.
Figure 3. Docking of 3-(2-phenylethynyl)benzenesulfonamide (10a)
(ball and stick) in the active site of ovine COX-1. Hydrogen atoms of
the amino acid residues have been removed to improve clarity.
(

R. Anana et al. / Bioorg. Med. Chem. 14 (2006) 5259–5265
5263
Table 2. In vivo anti-inflammatory and analgesic activities for phenylethynylbenzenesulfonamides (9e and 10a)
F
2 2
SO NH
SO2NH2
9
e
10a
a
b
Compound
Anti-inflammatory activity
Analgesic activity
%
inhibition at 3 h (75 mg/kg po dose)
% inhibition at 30 min
% inhibition at 60 min
9
1
e
0a
23.3 ± 2.5
17.6 ± 0.7
25.2 ± 3.3
79.9 ± 1.9
41.7 ± 5.9
58.3 ± 15.3
—
29.0 ± 10.6
83.3 ± 8.2
—
c,d
c,e
Aspirin
Celecoxib
c
c
41.1 ± 5.9
28.8 ± 10.6
a
Inhibitory activity in a carrageenan-induced rat paw edema assay. The results are expressed as means ± SEM (n = 4) following a 75 mg/kg oral dose
of the test compound.
b
Inhibitory activity in the rat 4% NaCl-induced abdominal constriction assay. The results are expressed as means ± SEM (n = 4) following a 75 mg/
kg oral dose of the test compound.
c
d
e
5
0 mg/kg oral dose.
ED50 = 129.0 mg/kg oral dose.
ED50 = 10.8 mg/kg oral dose.
explains the weak binding affinity of 10a toward COX-1
COX-1 IC50 = 31.6 lM) compared to COX-2 (COX-2
IC50 = 0.45 lM).
IC50 = 0.45 lM; COX-1 IC50 = 31.6 lM; SI > 70),
moderate in vivo anti-inflammatory activity, and good
analgesic activity.
(
In vivo anti-inflammatory and analgesic activities were
determined for compounds 9e and 10a that showed
superior in vitro COX-2 inhibitory potency and selectiv-
ity properties. In a carrageenan-induced rat paw edema
assay 9e produced a 23% reduction in inflammation at
5. Experimental
Melting points were determined on a Thomas-Hoover
capillary apparatus and are uncorrected. H NMR spec-
1
3
h postdrug administration for a 75 mg/kg oral dose
see data in Table 2). In comparison, the meta-benzene-
tra were measured on a Bruker AM-300 spectrometer in
CDCl or CDCl + DMSO-d with TMS as the internal
(
sulfonamide compound 10a produced a 17% decrease in
inflammation at 3 h postdrug administration for a
3
3
6
standard, where J (coupling constant) values are esti-
mated in Hz. Spin multiples are given as s (singlet), d
(doublet), t (triplet), q (quartet), m (multiplet), and br
(broad). Microanalyses were performed for C, H, and
N (MicroAnalytical Service Laboratory, Department
of Chemistry, University of Alberta) and were within
±0.4% of theoretical values. Silica gel column chroma-
tography was performed using Merck silica gel 60
ASTM (70–230 mesh). All reagents, purchased from
the Aldrich Chemical Company (Milwaukee, WI), were
used without further purification. Male Sprague–Daw-
ley rats, used in the anti-inflammatory and analgesic
screens, were purchased from Animal Health Services
at the University of Alberta, and experiments were
carried out using protocols approved by the Animal
Welfare Committee, University of Alberta.
7
5 mg/kg oral dose. Thus, 9 e and 10a are weaker anti-
inflammatory agents than the reference drug celecoxib
80% inhibition of inflammation at 3 h postdrug admin-
(
istration for a 50 mg/kg oral dose). In a rat 4% NaCl-in-
duced abdominal constriction (analgesic) assay, the
meta-benzenesulfonamide 10a exhibited superior anal-
gesic activity (58 and 83% inhibition of writhing at 30
and 60 min postdrug administration) for a 75 mg/kg oral
dose compared to the para-benzenesulfonamide 9e (41
and 29% inhibition of writhing at 30 and 60 min post-
drug administration).
4. Conclusions
The structure–activity relationships acquired indicate
that (i) a linear acetylene spacer between two vicinal
phenyl rings is a suitable template for the design of
new COX inhibitors, (ii) the position of the sulfonamide
6. General procedure for the synthesis of 2-, 3-, and 4-
(substituted-phenylethynyl)benzenesulfonamides (9–11)
(
SO NH ) pharmacophore on the C-1 phenyl ring is a
2
Triethylamine
(7 mL),
dichlorobis(triphenylphos-
2
determinant of COX-2 activity where the relative poten-
cy profile is generally meta > ortho and para, (iii) in the
group of meta-benzenesulfonamides (10), incorporation
of a C-2 3-methoxyphenyl or 3-fluorophenyl substituent
decreases COX-2 potency and selectivity, and (iv) 3-(2-
phenylethynyl)benzenesulfonamide (10a) exhibited po-
tent and selective in vitro COX-2 inhibition (COX-2
phine)palladium (42 mg, 0.06 mmol), and then cuprous
iodide (5.8 mg, 0.03 mmol) were added slowly with stir-
ring to a solution of either 2-iodobenzenesulfonamide
(8a, 290 mg, 1 mmol), 3- bromobenzenesulfonamide
(8b, 240 mg, 1 mmol) or 4-bromobenzenesulfonamide
(8c, 240 mg, 1 mmol), and a phenylacetylene (7,
1
R = H, OMe, OH, F; R = H, Me; 1 mmol) in THF

5264
R. Anana et al. / Bioorg. Med. Chem. 14 (2006) 5259–5265
(
3 mL) under an argon atmosphere at 25 °C. The reac-
tion was allowed to proceed for 16 h with stirring at
0 °C (for reactions using 8b or 8c), or at 50 °C and
6.5. 4-[2-(3-Fluorophenyl)ethynyl]benzenesulfonamide
(9e)
8
1
a reaction time of 5 h for reactions using 2-iodoben-
zenesulfonamide (8a). The reaction mixture was cooled
to 25 °C, the solvent was removed under reduced pres-
sure, and the residue was purified by silica gel column
chromatography using ethyl acetate/hexanes (1:4, v/v)
as eluent to afford the respective title compounds (9,
Yield, 58%; white solid; mp 176–178 °C; H NMR
(CDCl + DMSO-d ) d 6.40 (s, 2H, SO NH ), 6.94–
3
6
2
2
7.01 (m, 1H, 3-fluorophenyl H-4), 7.12 (dd, J = 8.5,
1.8 Hz, 1H, 3-fluorophenyl H-2), 7.20–7.27 (m, 2H, 3-
fluorophenyl H-5, H-6), 7.51 (d, J = 8.2 Hz, 2H, ben-
zenesulfonamide H-3, H-5), 7.81 (d, J = 8.2 Hz, 2H,
benzenesulfonamide H-2, H-6). Anal. Calcd for
C H FNO S: C, 61.08; H, 3.66; N, 5.09. Found: C,
1
9
0 or 11). Some physical and spectroscopic data for
a–e, 10a–d, and 11a–c are listed below.
1
4
10
2
6
0.98; H, 3.41; N, 4.90.
6
.1. 4-(2-Phenylethynyl)benzenesulfonamide (9a)
6
.6. 3-(2-Phenylethynyl)benzenesulfonamide (10a)
1
Yield, 65%; white crystals; mp 214–216 °C; H NMR
1
(
CDCl + DMSO-d ) d 6.50 (s, 2H, SO NH ), 7.21–
Yield, 59%; yellow crystals; mp 156–157 °C; H NMR
(CDCl + DMSO-d ) d 6.31 (s, 2H, SO NH ), 7.28–
3
6
2
2
7
.24 (m, 3H, phenyl H-3, H-4, H-5), 7.35–7.40 (m, 2H,
3
6
2
2
phenyl H-2, H-6), 7.46 (d, J = 8.2 Hz, 2H, benzenesulf-
onamide H-3, H-5), 7.75 (d, J = 8.2 Hz, 2H, benzene-
sulfonamide H-2, H-6). Anal. Calcd for C H NO S:
C, 65.35; H, 4.31; N, 5.44. Found: C, 65.28; H, 4.10;
N, 5.33.
7.30 (m, 3H, phenyl H-3, H-4, H-5), 7.39–7.46 (m, 3H,
phenyl H-2, H-6, benzenesulfonamide H-5), 7.56 (d,
J = 7.9 Hz, 1H, benzenesulfonamide H-4), 7.78–7.81
(m, 1H, benzenesulfonamide, H-6), 8.00 (s, 1H, benzene-
sulfonamide H-2). Anal. Calcd for C H NO SÆ1/
1
4
11
2
1
4
11
2
8
4.07; N, 5.34.
H O: C, 64.78; H, 4.37; N, 5.40. Found: C, 64.86; H,
2
6
(
.2. 4-[2-(4-Methylphenyl)ethynyl]benzenesulfonamide
9b)
6
.7. 3-[2-(4-Methylphenyl)ethynyl]benzenesulfonamide
(10b)
1
Yield, 52%; yellow solid; mp 229–231 °C; H NMR
(
CDCl + DMSO-d ) d 2.16 (s, 3H, CH ), 6.56 (s,
3 6 3
H, SO NH ), 6.96 (d, J = 7.9 Hz, 2H, 4-methylphenyl
1
2
Yield, 68%; white solid; mp 159–160 °C; H NMR
(CDCl + DMSO-d ) d 2.31 (s, 3H, CH ), 6.24 (s, 2H,
SO NH ), 7.10 (d, J = 7.9 Hz, 2H, 4-methylphenyl H-
3, H-5), 7.33–7.42 (m, 3H, 4-methylphenyl H-2, H-6,
benzenesulfonamide H-5), 7.57 (d, J = 7.9 Hz, 1H,
benzenesulfonamide H-4), 7.79 (d, J = 7.9 Hz, 1H, ben-
zenesulfonamide H-6), 8.00 (t, J = 1.2 Hz, 1H, benzene-
sulfonamide H-2). Anal. Calcd for C H NO S: C,
2
2
H-3, H-5), 7.20 (d, J = 7.9 Hz, 4-methylphenyl H-2,
H-6), 7.37 (d, J = 8.2 Hz, 2H, benzenesulfonamide
H-3, H-5), 7.67 (d, J = 8.2 Hz, 2H, benzenesulfona-
mide H-2, H-6). Anal. Calcd for C H NO S: C,
66.40; H, 4.83; N, 5.16. Found: C, 66.24; H, 4.76;
N, 5.15.
3
6
3
2
2
1
5
13
2
1
5
13
2
6
(
.3. 4-[2-(3-Methoxyphenyl)ethynyl]benzenesulfonamide
9c)
66.40; H, 4.83; N, 5.16. Found: C, 66.34; H, 5.21; N,
5.16.
1
Yield, 72%; white solid; mp 164–165 °C; H NMR
6.8. 3-[2-(3-Methoxyphenyl)ethynyl]benzenesulfonamide
(10c)
(
CDCl + DMSO-d ) d 3.63 (s, 3H, OCH ), 6.56 (s,
3 6 3
2
H, SO NH ), 6.73–6.77 (m, 1H, 3-methoxyphenyl
2 2
1
H-4), 6.86 (d, J = 2.1 Hz, 1H, 3-methoxyphenyl H-2),
.93 (d, J = 7.9 Hz, 1H, 3-methoxyphenyl H-6), 7.08
t, J = 7.9 Hz, 1H, 3-methoxyphenyl H-5), 7.40 (d,
J = 8.2 Hz, 2H, benzenesulfonamide H-3, H-5), 7.71
d, J = 8.2 Hz, 2H, benzenesulfonamide H-2, H-6).
Anal. Calcd for C H NO S: C, 62.70; H, 4.56; N,
Yield, 61%; white crystals; mp 120–122 °C; H NMR
6
(
(CDCl + DMSO-d ) d 3.76 (s, 3H, OCH ), 6.28 (s,
2H, SO NH ), 6.82–6.86 (m, 1H, 3-methoxyphenyl H-
3
6
3
2 2
4), 6.97 (s, 1H, 3-methoxyphenyl H-2), 7.04 (d, J =
7.9 Hz, 1H, 3-methoxyphenyl H-6), 7.20 (t, J = 7.9 Hz,
1H, 3-methoxyphenyl H-5), 7.41 (t, J = 7.9 Hz, 1H, ben-
zenesulfonamide H-5), 7.58 (d, J = 7.9 Hz, 1H, benzene-
sulfonamide H-4), 7.80 (d, J = 7.9 Hz, 1H,
benzenesulfonamide H-6), 8.01 (s, 1H, benzenesulfona-
mide H-2). Anal. Calcd for C H NO S: C, 62.70; H,
(
1
5
13
3
4
.87. Found: C, 62.43; H, 4.42; N, 4.71.
6
(
.4. 4-[2-(3-Hydroxyphenyl)ethynyl]benzenesulfonamide
9d)
1
5
13
3
4
.56; N, 4.87. Found: C, 62.63; H, 4.56; N, 4.80.
1
Yield, 70%; yellow solid; mp 233–234 °C; H NMR
(
CDCl + DMSO-d )
d
.66–6.69 (m, 1H, 3-hydroxyphenyl H-4), 6.80–6.83
6.52 (s, 2H, SO NH ),
6.9. 3-[2-(3-Fluorophenyl)ethynyl]benzenesulfonamide
(10d)
3
6
2
2
6
(
m, 2H, 3-hydroxyphenyl H-2, H-6), 6.99 (t,
1
J = 7.9 Hz, 1H, 3-hydroxyphenyl H-5), 7.41 (d,
J = 8.2 Hz, 2H, benzenesulfonamide H-3, H-5), 7.71
Yield, 66%; yellow solid; mp 148–149 °C; H NMR
(CDCl + DMSO-d ) d 6.35 (s, 2H, SO NH ), 6.95–
3
6
2
2
(
8
d, J = 8.2 Hz, 2H, benzenesulfonamide H-2, H-6),
.92 (s, 1H, OH). Anal. Calcd for C H NO S:
7.00 (m, 1H, 3-fluorophenyl H-4), 7.01–7.13 (m, 1H, 3-
fluorophenyl H-2), 7.20–7.31 (m, 2H, 3-fluorophenyl
H-5, H-6), 7.41 (t, J = 7.9 Hz, 1H, benzenesulfonamide
H-5), 7.57 (d, J = 7.9 Hz, 1H, benzenesulfonamide H-
1
4
11
3
C, 61.52; H, 4.06; N, 5.12. Found: C, 61.41; H,
.05; N, 5.02.
4

R. Anana et al. / Bioorg. Med. Chem. 14 (2006) 5259–5265
5265
4
), 7.81 (d, J = 7.9 Hz, 1H, benzenesulfonamide H-6),
.01 (s, 1H, benzenesulfonamide H-2). Anal. Calcd for
6.16. Analgesic assay
8
C H FNO S: C, 61.08; H, 3.66; N, 5.09. Found: C,
Analgesic activity was determined using a 4% sodium
chloride-induced abdominal constriction assay previous-
1
4
10
2
6
0.86; H, 3.92; N, 5.03.
2
2
ly reported.
6
.10. 2-(Phenylethynyl)benzenesulfonamide (11a)
1
Yield, 82%; white solid; mp 103–104 °C; H NMR
Acknowledgments
(
phenyl H-3, H-4, H-5), 7.40–7.50 (m, 3H, phenyl H-2,
CDCl ) d 5.23 (s, 2H, SO NH ), 7.20–7.24 (m, 3H,
3 2 2
We are grateful to (i) the Canadian Institutes of Health
Research (CIHR) (MOP-14712) for financial support of
this research and (ii) Rx&D-HRF/CIHR for a postdoc-
toral fellowship (to Q.H.C.).
H-6, benzenesulfonamide H-4), 7.55 (dt, J = 7.9 Hz,
1
.2 Hz, 1H, benzenesulfonamide H-5), 7.72 (d,
J = 7.9 Hz, 1H, benzenesulfonamide H-3), 8.07 (d,
J = 7.9 Hz, 1H, benzenesulfonamide H-6). Anal. Calcd
for C H NO S: C, 65.35; H, 4.31; N, 5.44. Found:
1
4
11
2
C, 65.14; H, 4.51; N, 5.42.
References and notes
6
(
.11. 2-[2-(4-Methylphenyl)ethynyl]benzenesulfonamide
11b)
1
2
3
. Vane, J. R. Nature 1971, 231, 232.
. Vane, J. R.; Botting, R. M. Inflamm. Res. 1998, 2, S78.
. Perini, R.; Fiorucci, R.; Wallace, J. L. Can. J. Gastroen-
terol. 2004, 18, 229.
1
Yield, 63%; brown solid; mp 125–126 °C; H NMR
(
(
CDCl ) d 2.40 (s, 3H, CH ), 5.20 (s, 2H, SO NH ), 7.22
d, J = 7.9 Hz, 4-methylphenyl H-3, H-5), 7.44–7.50 (m,
4. Masferrer, J. L.; Seibert, K.; Zweifel, B.; Needleman, P.
Proc. Natl. Acad. Sci. U.S.A. 1992, 89, 3917.
3
3
2
2
3
4
H, 4-methylphenyl H-2, H-6, benzenesulfonamide H-
), 7.52 (dt, J = 7.9 Hz, 1.2 Hz, 1H, benzenesulfonamide
5. Penning, T.; Talley, J. J.; Bertenshaw, S.; Carter, J.;
Collins, P.; Docter, S.; Graneto, M.; Lee, L.; Malecha, J.;
Miyashiro, J.; Rogers, R.; Rogier, D.; Yu, S.; Anderson,
G.; Burton, E.; Cogburn, J.; Gregory, S.; Koboldt, C.;
Perkins, W.; Seibert, K.; Veenhuizen, A.; Zhang, Y.;
Isakson, P. J. Med. Chem. 1997, 40, 1347.
H-5), 7.69 (d, J = 7.9 Hz, 1H, benzenesulfonamide H-3),
.07 (d, J = 7.9 Hz, 1H, benzenesulfonamide H-6). Anal.
Calcd for C H NO SÆ1/2 H O: C, 64.18; H, 4.99; N,
8
1
5
13
2
2
4
.99. Found: C, 63.92; H, 4.85; N, 4.66.
6
. Chan, C. C.; Boyce, S.; Brideau, C.; Charleson, S.;
Cromlish, W.; Ethier, D.; Evans, J.; Ford-Hutchinson,
A. W.; Forrest, M. J.; Gauthier, J. Y.; Gordon, R.;
Gresser, M.; Guay, J.; Kargman, S.; Kennedy, B.;
Leblanc, Y.; Leger, S.; Mancini, J.; O’Neill, G. P.; Ouellet,
M.; Patrick, D.; Percival, M. D.; Perrier, H.; Prasit, P.;
Rodger, I. J. Pharmacol. Exp. Ther. 1999, 290, 551.
. Talley, J. J. Prog. Med. Chem. 1999, 36, 201.
6
(
.12. 2-[2-(3-Fluorophenyl)ethynyl]benzenesulfonamide
11c)
1
Yield, 70%; yellow solid; mp 98–100 °C; H NMR
CDCl ) d 5.19 (s, 2H, SO NH ), 7.12–7.16 (m, 1H, 3-
(
3
2
2
7
8
fluorophenyl H-4), 7.27–7.47 (m, 3H, 3-fluorophenyl
H-2, H-5, H-6), 7.50–7.59 (m, 2H, benzenesulfonamide
H-4, H-5), 7.71 (d, J = 7.9 Hz, 1H, benzenesulfonamide
H-3), 8.08 (d, J = 7.9 Hz, 1H, benzenesulfonamide H-6).
. Dogn e´ , J. M.; Supuran, C. T.; Pratico, D. J. Med. Chem.
005, 48, 2251.
2
9
. Uddin, M. J.; Rao, P. N. P.; Knaus, E. E. Bioorg. Med.
Chem. Lett. 2004, 14, 1953.
Anal. Calcd for C H FNO S: C, 61.08; H, 3.66; N,
1
4
10
2
10. Uddin, M. J.; Rao, P. N. P.; Knaus, E. E. Bioorg. Med.
Chem. 2005, 13, 417.
5
.09. Found: C, 61.36; H, 3.91; N, 4.81.
1
1. Uddin, M. J.; Rao, P. N. P.; Rahim, M. A.; McDonald,
R.; Knaus, E. E. Bioorg. Med. Chem. Lett. 2004, 14, 4911.
2. Rao, P. N. P.; Chen, Q. H.; Knaus, E. E. Bioorg. Med.
Chem. Lett. 2005, 15, 4842.
6
.13. Molecular modeling (docking) studies
1
Docking experiments were performed using InsightII
software Version 2000.1 (Accelrys Inc.) running on a Sil-
icon Graphic Octane 2 R14000A workstation according
1
1
3. Chandraratna, R. A. S. U.S. Patent 5,349,105, 1994.
4. Chen, Q. H.; Rao, P. N. P.; Knaus, E. E. Bioorg. Med.
Chem. 2005, 13, 6425.
1
9
to a previously reported method.
1
5. Takahashi, S.; Kuroyama, Y.; Sonogashira, K.; Hagihara,
N. Synthesis 1980, 627.
6
.14. In vitro cyclooxygenase (COX) inhibition assays
1
1
6. Chau, M. M.; Kice, J. L. J. Org. Chem. 1977, 42, 3265.
7. Jaffe, H.; Leffler, J. E. J. Org. Chem. 1975, 40, 797.
The ability of the test compounds listed in Table 1 to
inhibit ovine COX-1 and COX-2 (IC50 value, lM) was
determined using an enzyme immuno assay (EIA) kit
18. Kurumbail, R. G.; Stevens, A. M.; Gierse, J. K.;
McDonald, J. J.; Stegeman, R. A.; Pak, J. Y.; Gildehaus,
D.; Miyashiro, J. M.; Penning, T. D.; Seibert, K.; Isakson,
P. C.; Stallings, W. C. Nature 1996, 384, 644.
(
MI, USA) according to previously reported
Catalog No. 560101, Cayman Chemical, Ann Arbor,
a
1
2
2
2
9. Rao, P. N. P.; Amini, H.; Li, H.; Habeeb, A. G.; Knaus,
E. E. J. Med. Chem. 2003, 46, 4872.
0. Uddin, M. J.; Rao, P. N. P.; Knaus, E. E. Bioorg. Med.
Chem. 2004, 12, 5929.
1. Winter, C. A.; Risley, E. A.; Nuss, G. W. Proc. Soc. Exp.
Biol. Med. 1962, 111, 544.
2. Fukawa, K.; Kawano, O.; Hibi, M.; Misaka, N.; Ohba, S.;
Hatanaka, Y. J. Pharmacol. Methods 1980, 4, 251.
2
0
method.
.15. Anti-inflammatory assay
Anti-inflammatory activity was performed using a
6
2
1
method described by Winter et al.