Design, Synthesis, and Biological Evaluation of 6-Substituted-3-(4-methanesulfonylphenyl)-4-phenylpyran-2-ones: A Novel Class of Diarylheterocyclic Selective Cyclooxygenase-2 Inhibitors

Article abstract of DOI:10.1021/jm0302391

A group of 6-alkyl (alkoxy or alkylthio)-4-aryl-3-(4-methanesulfonylphenyl)pyran-2-ones (14a-v), possessing either a H or F substituent at the para-position of the C-4 phenyl ring, were designed for evaluation as selective cyclooxygenase-2 (COX-2) inhibit

Full text of DOI:10.1021/jm0302391

4
872
J . Med. Chem. 2003, 46, 4872-4882
Design , Syn th esis, a n d Biologica l Eva lu a tion of
-Su bstitu ted -3-(4-m eth a n esu lfon ylp h en yl)-4-p h en ylp yr a n -2-on es: A Novel Cla ss
6
of Dia r ylh eter ocyclic Selective Cyclooxygen a se-2 In h ibitor s
P. N. Praveen Rao, Mohsen Amini, Huiying Li, Amgad G. Habeeb, and Edward E. Knaus*
Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, T6G 2N8, Canada
Received May 19, 2003
A group of 6-alkyl (alkoxy or alkylthio)-4-aryl-3-(4-methanesulfonylphenyl)pyran-2-ones (14a -
v), possessing either a H or F substituent at the para-position of the C-4 phenyl ring, were
designed for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors with in vivo antiin-
flammatory-analgesic activities. Although 6-ethylthio-3-(4-methanesulfonylphenyl)-4-phen-
ylpyran-2-one (14s) exhibited a very high in vitro COX-2 inhibitory potency (IC50 ) 0.0032
µM) and COX-2 selectivity (SI > 120 000), 14s exhibited moderate antiinflammatory activity
compared to celecoxib in a carrageenan-induced rat paw edema assay. In contrast, the less
potent (IC50 ) 0.10 µM), and less selective (SI ) 2880) COX-2 inhibitor 6-ethoxy-3-(4-
methanesulfonylphenyl)-4-phenylpyran-2-one (14i) exhibited good antiinflammatory activity
where a 1 mg/kg oral dose reduced inflammation 32 and 67% at 3 and 5 h postdrug
administration relative to the reference drug celecoxib where a 50 mg/kg oral dose reduced
inflammation by 79 and 58% at the respective 3 and 5 h time periods. Molecular modeling
studies, where 14i was docked in the active site of both COX-1 and COX-2, reveals that the
C-6 ethoxy substituent orients the pyran-2-one ring to position the SO
the vicinity of the secondary pocket in COX-2. The absence of this COX-2 secondary pocket in
2
Me pharmacophore in
5
23
the COX-1 binding site is due to the presence of the bulky Ile in COX-1 such that access to
the amino acid residues (Ile5 , Phe , Gln , and His ), which line the COX-2 secondary pocket
17
518
192
90
with which the SO
2
Me pharmacophore could interact, is hindered. The six-membered pyran-
2
-one ring system is a suitable central template to design selective COX-2 inhibitors.
In tr od u ction
Ch a r t 1. Representative Examples of Selective Tricyclic
COX-2 Inhibitors
The differential tissue distribution of cyclooxyge-
nase-1 (COX-1) and cyclooxygenase-2 (COX-2) provides
a rationale for the development of selective COX-2
inhibitors as antiinflammatory-analgesic agents that
lack the GI side effects exhibited by traditional nonste-
roidal antiinflammatory drugs (NSAIDs).1 This hy-
pothesis has been applied successfully in the design of
two highly selective tricyclic COX-2 inhibitors that
possess a diaryl heterocyclic ring template, namely
-4
5
,6
celecoxib (1), and rofecoxib (2), respectively (Chart 1).
In addition to its role in rheumatoid arthritis and
osteoarthritis, COX-2 is also implicated in colon cancer
and angiogenesis.7-9 Recent studies have shown that
the progression of Alzheimer’s disease is reduced among
some users of NSAIDs. Chronic treatment with selective
COX-2 inhibitors may therefore slow the progress of
1
0
Alzheimer’s disease, without causing GI damage.
Diarylheterocycles, and other central ring pharma-
cophore templates, have been extensively studied as
cyclooxygenase inhibitors. All these tricyclic molecules
possess 1,2-diaryl substitution on a central four-, five-,
or six-membered ring system such as cyclobutenone (3),
cyclopentene (4), isoxazole (5), pyrazole (1), 2-(5H)-
5
,11-15
furanone (2), or pyridine (6), respectively (Chart 1).
Structure-activity relationship (SAR) studies have
shown that for optimum COX-2 selectivity and inhibi-
*
To whom correspondence should be addressed. Phone: 780-492-
5
993. Fax: 780-492-1217. E-mail: eknaus@pharmacy.ualberta.ca.
1
0.1021/jm0302391 CCC: $25.00 © 2003 American Chemical Society
Published on Web 09/30/2003

Selective Cyclooxygenase-2 Inhibitors
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23 4873
Sch em e 1a
a
1
1
Reagents and conditions: (a) dry AlCl3, 1,2-dichloroethane, R -C6H5 (R ) H, F), 25 °C, 24 h; (b) thioanisole, 25 °C, 24 h; (c) H2O,
5 °C, 10 min; (d) aqueous Oxone, THF, MeOH, 25 °C, 4-5 h.
2
Sch em e 2a
fonylphenyl)-4-phenylpyran-2-ones as selective COX-2
inhibitors with antiinflammatory-analgesic activities.
Ch em istr y
The title 3,4-diphenylpyran-2-ones (14a -v), possess-
ing a central six-membered lactone ring with either a
6
-alkyl, alkoxy, or alkylthio substituent, were prepared
by the condensation of a substituted 2,3-diphenylcyclo-
prop-2-en-1-one (9a or 9b) with the respective pyri-
dinium ylide derivative of 11a -m as illustrated in
Schemes 1-4. 2-(4-Methanesulfonylphenyl)-3-phenyl-
cycloprop-2-en-1-one (9a ) and the 3-(4-fluorophenyl)
analogue (9b) were prepared using a one-pot reaction,
starting with tetrachlorocyclopropene 7 according to our
previously reported procedure as shown in Scheme 1.19
The pyridinium salts 11a -g were prepared by the
reaction of the respective haloalkyl ketone (10a -c) or
alkyl haloacetate (10d -g) with pyridine (Scheme 2).
The nucleophilic substitution reaction of either chloro-
acetyl chloride or bromoacetyl bromide with various
alcohols or thiols gave the respective alkyl haloacetate
(10h -i) or alkyl halothioacetate (10j-m ), which on
subsequent reaction with pyridine afforded the respec-
tive N-alkoxy-, or alkylthiocarbonylmethylpyridinium
halides (11h -m ) in moderate to good yields (33-68%)
as shown in Scheme 3.
a
Reagents and conditions: (a) pyridine, THF, 25 °C, 6 h.
tory potency, a SO2Me or SO2NH2 substituent at the
para-position of a phenyl ring, and that the presence of
a p-F substituent on the nonsulfonyl vicinal phenyl ring
improves in vivo activity.16 In a very recent letter, we
reported the design and synthesis of a novel class of
diarylheterocycle with a central six-membered lactone
(
pyran-2-one) ring which exhibited good in vitro COX-2
The 3,4-diarylpyran-2-ones (14a -v) were prepared in
low to moderate yields (8-44%) by condensation of a
2-(4-methanesulfonylphenyl)-3-phenylcycloprop-2-en-1-
one (9a or 9b) with a pyridinium salt (11a -m ) in the
presence of the base triethylamine. The initial ylide
compound that is formed in the reaction undergoes a
1
7
inhibitory potency and selectivity. The Merck Co. has
also developed novel methods to synthesize diarylhet-
erocycles having a central six-membered lactone (pyran-
2
-one) ring system.18 We now describe the design,
synthesis, and biological evaluation of a diverse group
of 6-alkyl-, 6-alkoxy-, or 6-alkylthio-3-(4-methanesul-
2
0-22
spontaneous ring expansion
reaction to produce the
Sch em e 3a
a
2
2
2
Reagents and conditions: (a) diethyl ether, R OH (R ) i-Bu or 4-Cl-C6H4-CH2), -23 °C f 25 °C, 4 h; (b) diethyl ether, R SH or
2
-
+
2
R S Na (R ) Me, Et, n-Pr or i-Pr), -23 °C f 25 °C, 4 h; (c) pyridine, THF, 25 °C, 6 h.

4
874 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23
Praveen Rao et al.
Sch em e 4a
In vitro enzyme inhibition studies for the C-6 alkyl
(Me, Et, i-Pr) subgroup of compounds (14a -e) showed
weak to good COX-2 inhibitory activity (IC50 values in
the 0.5-125.3 µM range) with 6-methyl-3-(4-methane-
sulfonylphenyl)-4-phenylpyran-2-one (14a ), showing the
best combination of COX-2 inhibitory potency and
selectivity index (IC50 ) 0.68 µM; SI ) 904). In this C-6
alkyl subgroup (14a -e) of compounds, a p-fluoro sub-
stituent on the C-4 phenyl ring decreased both COX-2
selectivity and inhibitory potency but increased COX-1
inhibitory potency (Table 1). In the C-6 alkoxy (OMe,
OEt, OPr-i, OBu-t, OBu-i, OCH2-C6H4-4-Cl) subgroup
of compounds 14 having a C-4 phenyl substituent, in
vitro COX-2 inhibitory activity may not be totally
dependent upon steric effects even though the C-6 OEt,
i-PrO, t-BuO, and i-BuO analogues were equipotent
(IC50 values in the 1.3 to 2.7 µM range). Introduction of
a C-6 4-chlorobenzyloxy substituent (14p ) significantly
reduced COX-2 inhibitory activity and selectivity (COX-2
IC50 ) 415.8 µM; COX-1 IC50 ) 50.7 µM; SI < 0.12) as
shown in Table 1. Compounds having a C-4 4-fluoro-
phenyl substituent are generally less potent COX-2
inhibitors than the corresponding C-4 phenyl analogues,
except for the C-6 OEt compound 14i (COX-2 IC50 )
0
.10 µM; COX-1 IC50 ) 288 µM; SI ) 2880). The C-6
substituent in the thioalkyl (MeS, EtS, n-PrS, i-PrS)
subgroup of compounds had a significant effect on
COX-2 inhibitory potency (EtS . MeS > inactive n-PrS
and i-PrS) and COX-2 selectivity. For example, the C-6
thioethyl compound 14s is a highly potent and selective
COX-2 inhibitor (COX-1 IC50 ) 386.2 µM; COX-2
IC50 ) 0.0032 µM; SI > 120 000) relative to the reference
drugs rofecoxib (COX-2 IC50 ) 0.43 µM; SI > 1162) and
celecoxib (COX-2 IC50 ) 0.057 µM; SI > 401). The in
vitro cyclooxygenase inhibition data for this series
a
Reagents and conditions: (a) benzene, Et3N, 25 °C, 16-18 h.
target 6-alkyl-, 6-alkoxy-, or 6-alkylthio-3-(4-methane-
sulfonylphenyl)-4-phenylpyran-2-ones (14a -v) having
a central six-membered lactone ring (pyran-2-one) as
illustrated in Scheme 4. No other regioisomer was
observed using the reaction conditions employed. The
(
14a -v) of compounds illustrate the flexibility of the
COX-2 active site in accommodating compounds with a
range of molecular volumes (293-390 Å ).
3
In an earlier communication, we attributed the excel-
lent in vitro COX-2 inhibitory activity exhibited by 14s
to the presence of a weak hydrogen bonding interaction
of the sulfur atom of the C-6 thioethyl (SEt) substituent
structures of compounds 14 were consistent with micro-
analytical and mass spectral data. 1H NMR nuclear
Overhauser enhancement (NOE) studies showed NOE
interactions between H-5 and the 6-alkyl (R ), alkoxy
OR ), or alkylthio (SR ) moiety, and between H-5 and
the C-4 o-phenyl hydrogens, which establishes the
5
30
17
2
with the OH of Ser
in the COX-2 binding site.
A
2
2
recent molecular modeling study has confirmed the
(
5
30
importance of Ser
in the COX-2 inhibitory potency of
2
6
diarylheterocyclic COX-2 inhibitors. To explain the
potent COX-2 (IC50 ) 0.10 µM) and weak COX-1
inhibitory (IC50 ) 288 µM) activity of 14i [6-ethoxy-3-
regiochemistry of the C-4 and C-5 phenyl rings.
Resu lts a n d Discu ssion
(
4-methanesulfonylphenyl)-4-(4-fluorophenyl)pyran-2-
The in vitro abilities (IC50 values) of the title com-
pounds (14a -v) to inhibit the isozymes COX-1 and
COX-2 were determined by modification of a previously
reported procedure (Table 1).23 The rational design of
selective COX-2 inhibitors frequently exploits the dif-
ference in the volume of the binding sites for COX-1 and
COX-2. Thus, a SO2Me or a SO2NH2 substituent placed
at the para-position of one of the phenyl rings can
interact with secondary pocket amino acid residues such
one], a molecular modeling study was performed where
14i was docked in the binding sites of both COX-1 and
COX-2. In addition, molecular dynamics (MD) simula-
tions were carried out to assess the stability of the
docked ligand-enzyme complexes. Docking 14i in the
COX-2 active site shows that it binds in the primary
2
binding site such that the p-SO Me substituent orients
9
0
toward the secondary pocket amino acid residues (His ,
1
92
513
518
523
352
Gln , Arg , Phe , Val , and Leu ) with one of
the O-atoms of the SO2Me substituent forming a hy-
drogen bond with the amide hydrogen of Phe5 (2.1 Å)
as shown in Figure 1. The CdO oxygen atom of the
central pyran-2-one ring is oriented toward Tyr3 which
is part of the entrance to the secondary pocket. This
CdO oxygen atom is positioned about 3.64 Å from the
9
0
192
518
513
as His , Gln , Phe , and Arg that are associated
18
with, and accessible from, the primary COX-2 binding
site.2
4,25
Accordingly, we have designed a novel class of
55
6
4
-substituted-3,4-diphenylpyran-2-ones having a C-3
-methanesulfonylphenyl substituent in conjunction
with either a C-4 phenyl, or 4-fluorophenyl substituent.

Selective Cyclooxygenase-2 Inhibitors
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23 4875
Ta ble 1. COX-1/COX-2 Inhibitory and Antiinflammatory-Analgesic Activities of 6-Alkyl-, 6-Alkoxy-, and
-Alkylthio-3-(4-methanesulfonylphenyl)-4-phenylpyran-2-ones (14a -v)
6
AI activityc
analgesic activityd
IC50 (µM)a
COX-1 COX-2
selectivityb % inhibition
% inhibition
at 5 h
% inhibition
at 30 min
% inhibition volume
at 60 min.
compd
R1
R2
index
at 3 h
(Å)
e
1
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
4q
4r
H
F
H
H
F
H
F
H
F
H
F
H
F
H
F
H
F
Me
Me
Et
i-Pr
i-Pr
Me
Me
Et
614.8
201.5
8.0
341.5
15.7
14.7
0.68
125.3
1.5
0.50
13.6
28.3
904
1.6
5.3
683
1.1
<0.5
>20
216
2880
2.0
6.7
>37
3.3
>1.7
1.2
< 0.2
5.6
12.5 ( 2.2
23.5 ( 3.2
57.0 ( 4.1
60.4 ( 7.3
293.5
296.6
310.1
326.7
329.8
301.7
305.5
318.7
322.3
336.0
338.7
351.3
355.6
351.7
355.5
386.5
390.8
311.5
328.5
331.2
344.6
345.6
209.5
298.5
267.2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
-
-
-
-
-
-
-
-
09.8 ( 3.1
19.5 ( 5.3
67.8 ( 9.1
56.9 ( 7.1
20.7 ( 5.4
83.4 ( 1.9
72.6 ( 4.6
-
35.8 ( 4.8
69.1 ( 4.9
50.9 ( 4.2
inactive
22.0 ( 5.4
55.2 ( 10.1
>1000 59.5
30.6 ( 4.4
30.0 ( 6.5
49.0 ( 10.5
281.5
288.0
4.0
560.0
>100
68.5
3.1
1.3
0.10
2.0
83.6
2.7
20.4
1.8
35.0
415.8
53.3
2.8
0.0032
1.44
>100
>100
-
-
-
Et
32.7 ( 5.3
67.8 ( 5.5
42.8 ( 8.2
75.7 ( 4.1
-
i-Pr
i-Pr
t-Bu
t-Bu
i-Bu
i-Bu
-
-
-
-
-
-
-
29.0 ( 2.8 f
30.1 ( 3.0 f
73.8 ( 4.0 g
80.9 ( 6.2
g
-
-
-
-
-
-
-
-
42.6
-
-
-
-
4-Cl-PhCH2 50.7
4-Cl-PhCH2 301.5
Me
Et
Et
n-Pr
i-Pr
-
-
-
-
-
-
-
-
H
H
F
H
H
>100
386.2
>100
>100
>100
>35
>120 687
>69
-
-
-
-
-
09.2 ( 3.0 f
25.8 ( 4.0 f
-
19.5 ( 2.4 f
81.0 ( 5.4 g
77.4 ( 8.1
g
g
4s
4t
4u
4v
16.8 ( 7.1 f
54.3 ( 11.5 g
66.0 ( 6.5
-
-
-
-
-
-
-
-
56.2 ( 2.0 f
41.5 ( 4.9
f
-
-
Ibuprofen
Celecoxib
Rofecoxib
f,h
58.2 ( 1.8 f
31.7 ( 9.6 g
g
22.9
>500
0.057
0.43
>401
>1162
79.9 ( 1.9
62.0 ( 7.3
-
-
-
-
a
Values are means of two determinations and deviation from the mean is <10% of the mean value. b In vitro COX-2 selectivity index
c
(
4
IC50 COX-1/IC50 COX-2). Inhibitory activity on carrageenan-induced rat paw edema. The results are expressed as mean ( SEM (n )
-6) following a 1 mg/kg oral dose of the test compound. d Inhibitory activity in the rat 4% NaCl-induced abdominal constriction assay.
e
The results are expressed as mean ( SEM (n ) 4-6) following a 1 mg/kg intraperitoneal dose of the test compound. The volume of the
f
g
molecule, after minimization using the PM3 force field, was calculated using the Alchemy 2000 program. 50 mg/kg po dose. 50 mg/kg
h
ip dose. ID50 ) 10.8 mg/kg po dose.
OH of Tyr355 and the O-atom of the central pyran-2-
one ring is about 4.7 Å from the NH2 (guanidino group)
of Arg1 . The C-4-substituted phenyl ring lies in a
C-6 OEt substituent with Ser530 that may contribute to
the in vitro COX-2 inhibitory activity of 14i. The
20
355
importance of Tyr
in the binding affinities of diaryl-
3
85
387
hydrophobic cavity lined by Tyr
and Trp
with the
heterocyclic COX-2 inhibitors was shown in a recent
3
55
p-fluoro substituent located about 5.8 Å away from the
study, wherein mutation of Tyr
to Ala in the COX-2
3
85
OH of Tyr and where the distance between the center
of the C-4 phenyl ring and the OH of Ser530 was about
active site led to increased dissociation rates of celecoxib
29
and valdecoxib. Docking 14i in the COX-1 active site
5
30
6
.9 Å. A recent study has shown the importance of Ser
suggests that the CdO oxygen atom is separated by a
2
6
355
in the COX-2 inhibitory activity of rofecoxib. Accord-
greater distance from the OH of Tyr
(5.0 Å) than
ingly, the C-6 ethoxy (OEt) substituent of 14i is located
observed for a similar interaction in COX-2 (3.64 Å), and
that insertion of the p-SO2Me substituent into the
secondary pocket is sterically impeded by the bulky
3
49
345
530
in a hydrophobic region formed by Val , Ile , Ser
,
5
31
535
Leu , and Met
with the O-atom of C-6 OEt sub-
5
23
stituent positioned about 4.9 Å away from the OH of
Ile as shown in Figure 2. In addition, the C-6 ethoxy
Ser5 (Figure 1).
30
oxygen atom is further removed (5.5 Å) from the OH of
5
30
Similar docking of 14i on the COX-1 active site
showed the drug-enzyme binding interaction was not
dramatically different from that observed in COX-2
Ser
compared to COX-2 (4.9 Å). It has been shown
that a single amino acid difference (Ile/Val) at position
523 in the respective active sites of COX-1 and COX-2
can be exploited to design diarylheterocyclic COX-2
(Figure 2). However, closer examination revealed po-
2
4,25
tentially crucial interactions involving the central py-
inhibitors.
However, a recent molecular modeling
ran-2-one CdO with the key active site amino acid
study of the diarylheterocyclic COX-2 inhibitor rofecoxib
3
55
residue Tyr , the interaction of the C-3 p-SO2Me
substituent with Ile/Val5 that forms part of the
entrance to the secondary pocket and interaction of the
in the COX-1 active site has shown that steric hindrance
23
523
due to the substitution of Ile/Val
is not enough to
2
7
prevent binding of the ligand to COX-1. Recent studies

4
876 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23
Praveen Rao et al.
F igu r e 1. Docking 6-ethoxy-3-(4-methanesulfonylphenyl)-4-(4-fluorophenyl)pyran-2-one (14i) (ball-and-stick) in the active site
of murine COX-2 (Eintermolecular ) -60.7 kcal/mol). Hydrogens atoms are not shown for clarity.
have also shown that COX-2 inhibitors belonging to the
diarylheterocyclic class show time dependent inhibition
of COX-2 while exhibiting competitive and reversible
inhibition of COX-1.28,29 Consequently, the higher bind-
ing affinity exhibited by 14i for COX-2 may be due in
part to its slow dissociation from COX-2. This possibility
is consistent with results from a molecular dynam-
ics simulation of 14i docked in the active site of
COX-2 which showed a lower intermolecular energy
different time intervals as shown in Table 1. 6-Ethoxy-
3-(4-methanesulfonylphenyl)-4-(4-fluorophenyl)pyran-2-
one (14i) was the most potent antiinflammatory agent
in this series, producing a 32 and 67% reduction in
inflammation at 3 and 5 h postdrug administration,
respectively, for a 1 mg/kg oral dose. This in vivo
antiinflammatory activity parallels its in vitro COX-2
potency and selectivity (COX-2 IC50 ) 0.10 µM; SI )
2880). In general, the C-6 alkyl- and alkoxy-substituted
compounds, which possess a p-fluoro substituent on the
C-4 phenyl ring, exhibit good antiinflammatory activity
(Table 1). In contrast, the C-6 thioethyl compound 14s,
which exhibited excellent in vitro COX-2 potency and
selectivity (IC50 ) 0.0032 µM; SI > 120 000), was a weak
antiinflammatory agent (9 and 19.5% reduction in
inflammation at 3 and 5 h postdrug administration,
respectively) for a 50 mg/kg oral dose. When 14s was
administered at lower doses (1, 5, and 10 mg/kg oral
dose), it did not exhibit antiinflammatory activity. It is
possible that 14s which has a SEt substitutent at the
C-6 position of the pyranone ring may be more suscep-
tible to metabolic inactivation compared to C-6 alkyl or
alkoxy analogues when administered by the oral route
which may result in a lower amount of the drug
localization at the inflammation site. Studies using
systemic routes of administration may provide more
precise explanations for these observations which are
not clear.
(Eintermolecular ) -60.7 kcal/mol) for this ligand-enzyme
complex as compared to 14i docked in the active site of
COX-1 (Eintermolecular ) -49.3 kcal/mol).
In vivo pharmacological evaluation of some title
compounds 14 was carried out to assess their potential
antiinflammatory and analgesic activities. Initial com-
pound selection for in vivo screening was based on in
vitro COX-1/COX-2 enzyme inhibition data obtained.
Qualitative structure-activity relationship data, ac-
quired using the antiinflammatory rat paw edema
assay, showed that this group of C-6 alkyl-, alkoxy-, or
alkylthio-substituted 3-(4-methanesulfonylphenyl)-4-
phenylpyran-2-ones exhibit antiinflammatory activity
in the inactive to good activity range (inactive to 69%
inhibition) (Table 1). In the C-6 alkyl series (14a , 14d ,
and 14e), 6-isopropyl-3-(4-methanesulfonylphenyl)-4-(4-
fluorophenyl)pyran-2-one (14e) was the most active
antiinflammatory agent (35 and 69% reduction in
inflammation at 3 and 5 h postdrug administration,
respectively) for a 1 mg/kg oral dose as compared to
reference drug celecoxib (79 and 58% reduction in
inflammation at 3 and 5 h postdrug administration,
respectively) for a 50 mg/kg oral dose.
It is interesting that the C-6 alkyl (14a , 14d , and 14e)
and the C-6 alkoxy (14f, 14g, and 14i) compounds
increased rat paw edema volume when administered at
a higher 5 and 10 mg/kg oral dose although the data
obtained are not statistically significant. Over the years
numerous studies employing rat acute models of inflam-
The C-6 alkoxy-substituted group of compounds (14f,
1
4g, 14i, and 14l) reduced inflammation by 0-67% at

Selective Cyclooxygenase-2 Inhibitors
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23 4877
F igu r e 2. Docking 6-ethoxy-3-(4-methanesulfonylphenyl)-4-(4-fluorophenyl)pyran-2-one (14i) (ball-and-stick) in the active site
of ovine COX-1 (Eintermolecular ) -49.3 kcal/mol). Hydrogens atoms are not shown for clarity.
mation have not been able to completely assess the
contribution of the COX-2 enzyme in the inflammatory
process. Recent studies have shown that in a rat
carrageenan-induced pleurisy model, rofecoxib increased
the levels of proinflammatory cytokine TNF-R in rat
paw.30 In addition, studies have implicated increased
levels of inducible nitric oxide synthase in the carra-
geenan-induced rat paw inflammation assay which was
not altered by the administration of COX-2 inhibi-
dose relative to the reference drug celecoxib (31 and 62%
inhibition at 30 and 60 min postdrug administration for
a 50 mg/kg intraperitoneal dose). The good analgesic
activity exhibited by C-6 alkyl (14a , 14d , and 14e) and
alkoxy (14f, 14g, and 14i) compounds at the 1 mg/kg
intraperitoneal dose suggests roles for both peripheral
and central actions of COX-2 inhibitors in alleviating
3
4,35
pain in a wide variety of conditions.
3
1,32
tors.
Another recent article has shown the opposite
Con clu sion s
effects of rofecoxib on activating protein (AP-1) and
The qualitative structure-activity relationships ac-
quired for this novel class of 6-alkyl (alkoxy or alkyl-
thio)-3-(4-methanesulfonylphenyl)-4-phenylpyran-2-
ones have shown that (i) a six-membered lactone (pyran-
nuclear factor-κB (NF-κB) which may explain the lack
of clear dose dependency, influencing both its wanted
and unwanted effects.33 Although the exact mechanisms
for these observations are not clear, there are multiple
factors that may be responsible for the increase in rat
paw volume observed at higher doses for the compounds
described in this study.
Analgesic activity was determined using the 4% NaCl-
induced abdominal constriction assay. Compounds from
the C-6 alkyl (14a , 14d , and 14e) and C-6 alkoxy (14f,
2
-one) ring serves as a suitable central ring template
to design selective COX-2 inhibitors when the CdO
oxygen atom is suitably positioned to undergo hydrogen
3
55
bonding to Tyr
in the COX-2 binding site, (ii) the
combined steric and electronic properties of the C-6
central substituted ring modulates COX-2 inhibitory
potency and selectivity by orienting the C-3 p-SO2Me
phenyl substituent to the vicinity of the secondary
pocket in the COX-2 binding site, vis a vis 14i (C-6
ethoxy) and 14s (C-6 ethylthio) exhibit excellent COX-2
inhibitory potency and selectivity, and (iii) the moderate
to weak COX-1 inhibition exhibited by this class of
compounds can be attributed partly to the steric hin-
1
4g, 14i, and 14l) subgroups exhibited a 20-83%
inhibition of writhing at different time intervals with
4i [6-ethoxy-3-(4-methanesulfonylphenyl)-4-phenylpy-
1
ran-2-one] exhibiting 42 and 75% inhibition in writhing
at 30 and 60 min, respectively, postdrug administration
for a 1 mg/kg intraperitoneal dose (Table 1). 6-Ethylthio-
3
-(4-methanesulfonylphenyl)-4-phenylpyran-2-one (14s)
5
23
was the most active analgesic agent where writhing was
reduced by 81 and 77% inhibition at 30 and 60 min
postdrug administration for a 50 mg/kg intraperitoneal
drance of Ile at the entrance to the side pocket which
blocks the access of the p-SO2Me substituent, and (iv)
the presence of a p-fluoro substituent on the C-4 phenyl

4
878 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23
Praveen Rao et al.
cm- (CdO); H NMR (DMSO-d
1
1
): δ 1.01 (t, J ) 6.7 Hz, 3H,
ring improves in vivo antiinflammatory activity for this
class of compounds.
6
CH CH
2
3
2 3
), 2.64 (q, J ) 6.7 Hz, 2H, CH CH ), 5.76 (s, 2H,
), 8.18 (dd, J ) 7.9, J ) 5.5 Hz, 2H, pyridine H-3, H-5),
+
N CH
2
8
5
.64 (dd, J ) 7.9, J ) 7.9 Hz, 1H, pyridine H-4), 8.84 (d, J )
.5 Hz, 2H, pyridine H-2, H-6).
Exp er im en ta l Section
Gen er a l. Melting points were determined using a Buchi
capillary apparatus and are uncorrected. Ibuprofen was pur-
chased from Sigma (St. Louis, MO). All other reagents includ-
ing 10a -g were purchased from Aldrich (Milwaukee, WI).
Silica gel column chromatography was performed using Merck
silica gel 60 ASTM (70-230 mesh). Infrared (IR) spectra were
recorded using a Nicolet 550 Series II Magna FT-IR spectrom-
eter. Nuclear magnetic resonance ( H NMR, C NMR) spectra
were recorded on a Bruker AM-300 spectrometer, and chemical
shifts are expressed in parts per million (ppm, δ) relative to
tetramethylsilane as internal standard. Spin multiplets are
given as s (singlet), d (doublet), dd (doublet of doublets), t
N-(Isop r op ylca r b on ylm et h yl)p yr id in iu m
11c). This product was obtained as a solid (0.69 g, 51.4%) by
Br om id e
(
reaction of pyridine with 10c: mp 148-150 °C; IR (KBr) 1658
-1
1
cm (CdO); H NMR (DMSO-d
CH(CH ], 3.76-3.83 [m, 1H, CH(CH
.27 (dd, J ) 7.9, J ) 5.5 Hz, 2H, pyridine H-3, H-5), 8.74 (dd,
6
): δ 1.38 [d, J ) 6.7 Hz, 6H,
+
3
)
2
3 2 2
) ], 6.00 (s, 2H, N CH ),
8
J ) 7.9, J ) 7.9 Hz, 1H, pyridine H-4), 9.08 (d, J ) 5.5 Hz,
H, pyridine H-2, H-6).
1
13
2
N-(Meth oxycar bon ylm eth yl)pyr idin iu m Br om ide (11d).
This product was obtained as a white solid (0.41 g, 32.4%) by
reaction of pyridine with 10d : mp 176-178 °C (lit. 174-175
37
-1
1
°
(
C ); IR (KBr): 1745 cm (CdO); H NMR (DMSO-d
6
): δ 3.75
(
triplet), q (quartet), and m (multiplet). Coupling constants (J )
+
s, 3H, OCH ), 5.93 (s, 2H, N CH ), 8.04 (dd, J ) 7.9, J ) 5.5
3
2
1
3
are given in hertz (Hz). C NMR spectra were acquired using
the J modulated spin-echo technique where methyl and
methane carbons appear as positive peaks and methylene and
quaternary carbon resonances appear as negative peaks. High-
resolution mass spectra (HRMS) were acquired using a Kratos
MS-50 electron impact (EI) mass spectrometer. Microanalyses
were performed for C, H, and N (MicroAnalytical Service
Laboratory, Department of Chemistry, University of Alberta)
and were within ( 0.4% of the theoretical values. Celecoxib
and rofecoxib were synthesized according to the literature
Hz, 2H, pyridine H-3, H-5), 8.54 (dd, J ) 7.9, J ) 7.9 Hz, 1H,
pyridine H-4), 9.30 (d, J ) 5.5 Hz, 2H, pyridine H-2, H-6).
N-(Eth oxyca r bon ylm eth yl)p yr id in iu m Br om id e (11e).
This product was obtained as a white solid (0.43 g, 31.8%) by
reaction of pyridine with 10e: mp 132-134 °C (lit. 134-136
3
7
-1
1
°
(
C ); IR (KBr): 1750 cm (CdO); H NMR (DMSO-d
CH
), 8.22 (dd, J ) 7.9, J ) 5.5 Hz, 2H,
6
): δ 1.23
t, J ) 6.7 Hz, 3H, OCH
CH ), 5.65 (s, 2H, N CH
3 2
pyridine H-3, H-5), 8.69 (dd, J ) 7.9, J ) 7.9 Hz, 1H, pyridine
H-4), 9.04 (d, J ) 5.5 Hz, 2H, pyridine H-2, H-6).
2
3
), 4.20 (q, J ) 6.7 Hz, 2H, OCH -
2
+
5
,14
procedures.
-phenylcycloprop-2-en-1-one], and 9b [2-(4-methanesulfonyl-
phenyl)-3-(4-fluorophenyl)cycloprop-2-en-1-one], were prepared
Compounds 9a [2-(4-methanesulfonylphenyl)-
N-(Isop r op yloxyca r bon ylm eth yl)p yr id in iu m Br om id e
11f). This product was obtained as a white solid (0.92 g, 65%)
3
(
1
9
by reaction of pyridine with 10f: mp 90-91 °C (lit. 79-81
according to the previously reported method. Male Spargue-
Dawley rats, used in the antinflammatory-analgesic screens,
were supplied by Animal Health Services, University of
Alberta and experiments were carried out using protocols
approved by the Animal Welfare Committee, University of
Alberta.
3
7
-1
1
°
[
5
C ); IR (KBr) 1751 cm (CdO); H NMR (DMSO-d
], 5.01-5.13 [m, 1H, OCH(CH
), 8.27 (dd, J ) 7.9, J ) 5.5 Hz, 2H, pyridine
6
): δ 1.25
d, J ) 6.7 Hz, 6H, OCH(CH
.72 (s, 2H, N CH
2
H-3, H-5), 8.74 (dd, J ) 7.9, J ) 7.9 Hz, 1H, pyridine H-4),
.14 (d, J ) 5.5 Hz, 2H, pyridine H-2, H-6).
3
)
2
3 2
)
],
+
9
N-(ter t-Bu toxyca r bon ylm eth yl)p yr id in iu m Br om id e
11g). This product was obtained as a semisolid (0.70 g, 47%)
Gen er a l P r oced u r e for th e Syn th esis of Alk yl Ha lo-
a ceta tes (10h -i) a n d Alk yl Ha loth ioa ceta tes (10j-m ). To
a stirred solution of either bromoacetyl bromide or chloroacetyl
chloride (13.3 mmol) in dry diethyl ether (65 mL) was added
(
-
1
by reaction of pyridine with 10g: IR (KBr): 1746 cm (Cd
1
O); H NMR (DMSO-d
6
): δ 1.58 [s, 9H, OC(CH
3 3
) ], 5.83 (s, 2H,
+
N CH
2
), 8.27 (dd, J ) 7.9, J ) 5.5 Hz, 2H, pyridine H-3, H-5),
1
3.3 mmol of the respective alcohol (i-BuOH or 4-chlorobenzyl
alcohol) or thiol (MeSNa, EtSH, n-PrSH or i-PrSH) at -23 °C
dry ice/acetone bath) under an argon atmosphere, and the
reaction was allowed to proceed at 25 °C for 4 h. The reaction
mixture was washed with 10% NaHCO solution (30 mL), and
the organic phase was separated, and dried (Na SO ). The
8
5
.73 (dd, J ) 7.9, J ) 7.9 Hz, 1H, pyridine H-4), 9.14 (d, J )
.5 Hz, 2H, pyridine H-2, H-6).
(
N-(Isob u t oxyca r b on ylm et h yl)p yr id in iu m Br om id e
11h ). This product was obtained as a white solid (1.0 g, 68%)
(
3
by reaction of pyridine with 10h : mp 86-88 °C; IR (KBr):
2
4
-
1
1
1
6
[
(
7
748 cm (CdO); H NMR (DMSO-d
H, OCH CH(CH ], 1.84-1.95 [m, 1H, OCH
CH(CH ], 5.80 (s, 2H, N CH
6
): δ 0.88 [d, J ) 6.7 Hz,
solvent was removed either in vacuo, or under a stream of
argon, to afford the respective alkyl haloacetate (10h -i) or
alkyl halothioacetate (10j-m ) as a pale yellow oil in 59-85%
yield. Products 10 were used immediately without further
purification for the preparation of compounds 11.
2
3
)
2
2
CH(CH
3
)
2
2
], 3.96
), 8.27
+
d, J ) 6.7 Hz, 2H, OCH
2
3
)
2
dd, J ) 7.9, J ) 5.5 Hz, 2H, pyridine H-3, H-5), 8.74 (dd, J )
.9, J ) 7.9 Hz, 1H, pyridine H-4), 9.15 (d, J ) 5.5 Hz, 2H,
pyridine H-2, H-6).
Gen er a l P r oced u r e for th e Syn th esis of N-Alk yl-,
-
Alk oxy-, or -Alk ylth ioca r bon ylm eth ylp yr id in iu m Ha -
lid es (11a -m ). To a stirred solution of dry pyridine (0.45 mL,
.5 mmol) in dry THF (30 mL) under an argon atmosphere
was added either an alkyl ketone (10a -c), alkyl haloacetate
10d -i), or alkyl halothioacetate (10j-m ) (5.5 mmol), and the
N-(4-Ch lor oben zyloxycar bon ylm eth yl)pyr idin iu m Br o-
m id e (11i). This product was obtained as a semisolid (0.71 g,
-
1
5
38%) by reaction of pyridine with 10i: IR (KBr): 1746 cm
1
(CdO); H NMR (DMSO-d
6
): δ 5.26 (s, 2H, 4-Cl-C
6
H
4
2
-CH ),
+
(
5.79 (s, 2H, N CH ), 7.41 (d, J ) 8.5 Hz, 2H, 4-chlorophenyl
2
reaction mixture was stirred for 6 h at 25 °C. The solvent was
either removed in vacuo, or under a stream of argon gas, and
the solid or semisolid product obtained was purified by
recrystallization from ethanol-acetone (1:1, v/v) to give the
respective product (11a -m ) in 33-88% yield. Some physical
H-2, H-6), 7.45 (d, J ) 8.5 Hz, 2H, 4-chlorophenyl H-3, H-5),
8.26 (dd, J ) 7.9, J ) 5.5 Hz, 2H, pyridine H-3, H-5), 8.73 (dd,
J ) 7.9, J ) 7.9 Hz, 1H, pyridine H-4), 9.14 (d, J ) 5.5 Hz,
2H, pyridine H-2, H-6).
N-(Met h ylt h ioca r b on ylm et h yl)p yr id in iu m Br om id e
(11j). This product was obtained as a white solid (0.93 g,
68.3%) by reaction of pyridine with 10j: mp 225-226 °C; IR
1
and spectroscopic (IR, HNMR) data for 11a -m are listed
below.
-
1
1
N-(Meth ylca r bon ylm eth yl)p yr id in iu m Ch lor id e (11a ).
This product was obtained as a white solid (0.41 g, 44%) by
reaction of pyridine with 10a : mp 205-206 °C (lit. 202-204
(KBr): 1667 cm (CdO); H NMR (DMSO-d
6
): δ 2.5 (s, 3H,
+
SCH ), 5.99 (s, 2H, N CH ), 8.23 (dd, J ) 7.9, J ) 5.5 Hz, 2H,
3
2
pyridine H-3, H-5), 8.66 (dd, J ) 7.9, J ) 7.9 Hz, 1H, pyridine
3
6
-1
1
°
(
C ); IR (KBr): 1658 cm (CdO); H NMR (DMSO-d
6
): δ 2.32
8 10
H-4), 9.02 (d, J ) 5.5 Hz, 2H, pyridine H-2, H-6). Anal. (C H -
+
s, 3H, CH
3
), 5.79 (s, 2H, N CH
2
), 8.23 (dd, J ) 7.9, J ) 5.5
BrNOS): C, H, N.
Hz, 2H, pyridine H-3, H-5), 8.68 (dd, J ) 7.9, J ) 7.9 Hz, 1H,
pyridine H-4), 9.01 (d, J ) 5.5 Hz, 2H, pyridine H-2, H-6).
N-(Eth ylca r bon ylm eth yl)p yr id in iu m Br om id e (11b).
This product was obtained as a white solid (0.64 g, 50.7%) by
reaction of pyridine with 10b: mp 179-181 °C; IR (KBr): 1660
N-(Ethylthiocarbonylmethyl)pyridinium Bromide (11k).
This product was obtained as a white solid (0.50 g, 33%) by
reaction of pyridine with 10k : mp 173-175 °C; IR (KBr): 1673
-
1
1
cm (CdO); H NMR (DMSO-d
6
): δ 1.24 (t, J ) 6.7 Hz, 3H,
CH ), 5.99 (s, 2H,
SCH CH ), 3.00 (q, J ) 6.7 Hz, 2H, SCH
2
3
2
3

Selective Cyclooxygenase-2 Inhibitors
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23 4879
+
N CH
8
5
2
), 8.26 (dd, J ) 7.9, J ) 5.5 Hz, 2H, pyridine H-3, H-5),
pyranone H-5), 7.05-7.08 (m, 2H, phenyl H-2, H-6), 7.23-7.34
(m, 3H, phenyl H-3, H-4, H-5), 7.36 (d, J ) 8.5 Hz, 4-meth-
anesulfonylphenyl H-2, H-6), 7.78 (d, J ) 8.5 Hz, 2H, 4-meth-
.73 (dd, J ) 7.9, J ) 7.9 Hz, 1H, pyridine H-4), 9.05 (d, J )
.5 Hz, 2H, pyridine H-2, H-6).
anesulfonylphenyl H-3, H-5). Anal. (C21
20 4
H O S): C, H.
N-(P r op ylt h ioca r b on ylm et h yl)p yr id in iu m Br om id e
(
11l). This product was obtained as a viscous oil (0.65 g, 43%)
6-Isop r op yl-3-(4-m eth a n esu lfon ylp h en yl)-4-(4-flu or o-
p h en yl)p yr a n -2-on e (14e). The product was obtained by
condensation of 9b with 11c in the presence of triethylamine
(0.06 g, 16%): mp 188-189 °C; IR (KBr): 1710 (CdO), 1312,
-
1
by reaction of pyridine with 10l: IR (KBr): 1675 cm (CdO);
1
H NMR (DMSO-d
.52-1.55 (m, 2H, SCH
SCH CH CH ), 6.00 (s, 2H, N CH
6
): δ 0.90 (t, J ) 7.3 Hz, 3H, SCH
CH CH ), 2.96 (t, 2H, J ) 7.0 Hz,
), 8.23 (dd, J ) 7.9, J ) 5.5
2 2 3
CH CH ),
1
2
2
+
3
-1 1
2
2
3
2
1148 (SO
CH(CH
6.13 (s, 1H, pyranone H-5), 6.98 (dd, J HH ) 8.7, J FH ) 8.7
2
) cm ; H NMR (CDCl
3
): δ 1.36 [d, J ) 7.0 Hz, 6H,
Hz, 2H, pyridine H-3, H-5), 8.70 (dd, J ) 7.9, J ) 7.9 Hz, 1H,
pyridine H-4), 9.04 (d, J ) 5.5 Hz, 2H, pyridine H-2, H-6).
3
)
2
], 2.87-2.93 [m, 1H, CH(CH
3
)
2
], 3.05 (s, 3H, SO CH ),
2
3
3
3
Hz, 2H, 4-fluorophenyl H-3, H-5), 7.07 (dd, J 3HH ) 8.7, J FH
4
)
N-(Isop r op ylth ioca r bon ylm eth yl)p yr id in iu m Br om id e
5
.2 Hz, 2H, 4-fluorophenyl H-2, H-6), 7.38 (d, J ) 8.2 Hz,
(
11m ). This product was obtained as a semisolid (0.57 g, 38%)
-
1
4-methanesulfonylphenyl H-2, H-6), 7.83 (d, J ) 8.2 Hz, 2H,
4-methanesulfonylphenyl H-3, H-5. Anal. (C H FO S): C, H.
by reaction of pyridine with 10m : IR (KBr): 1672 cm (Cd
1
O); H NMR (DMSO-d
CH ], 3.76-3.83 [m, 1H, SCH(CH
.27 (dd, J ) 7.9, J ) 5.5 Hz, 2H, pyridine H-3, H-5), 8.74 (dd,
6
): δ 1.38 [d, J ) 6.7 Hz, 6H, SCH-
21 19
4
+
(
8
3
)
2
3
)
2
], 6.00 (s, 2H, N CH
2
),
6-Met h oxy-3-(4-m et h a n esu lfon ylp h en yl)-4-p h en ylp y-
r a n -2-on e (14f). The product was obtained as a solid by
condensation of 9a with 11d in the presence of triethylamine
(0.04 g, 12%): mp 110-112 °C; IR (KBr): 1719 (CdO), 1310,
J ) 7.9, J ) 7.9 Hz, 1H, pyridine H-4), 9.08 (d, J ) 5.5 Hz,
2
H, pyridine H-2, H-6).
-
1
1
1
4
2
145 (SO
.03 (s, 3H, OCH
H, phenyl H-2, H-6), 7.21-7.31 (m, 3H, phenyl H-3, H-4, H-5),
2
) cm ; H NMR (CDCl
3
): δ 3.02 (s, 3H, SO
2 3
CH ),
Gen er a l P r oced u r e for t h e Syn t h esis of 6-Alk yl,
a lk oxy-, or -a lk ylth io-3-(4-m eth a n esu lfon ylp h en yl)-4-
3
), 5.59 (s, 1H, pyranone H-5), 7.06-7.09 (m,
-
p h en ylp yr a n -2-on es (14a -v). To a solution of the N-alkyl,
-
alkoxy-, or -alkylthiocarbonylmethylpyridinium salt selected
7.33 (d, J ) 8.5 Hz, 4-methanesulfonylphenyl H-2, H-6), 7.75
(d, J ) 8.5 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5). Anal.
(C19H O S): C, H.
16 5
(11a -m , 2.4 mmol) in dry benzene (60 mL) at 25 °C was added
freshly distilled triethylamine (1 mL, 7 mmol). To this reaction
mixture was added 2-(4-methanesulfonylphenyl)-3-phenylcy-
cloprop-2-en-1-one (9a , 0.29 g, 1 mmol) or 2-(4-methanesul-
fonylphenyl)-3-(4-fluorophenyl)cycloprop-2-en-1-one (9b, 0.31
g, 1 mmol), and the mixture was stirred for 16-18 h at 25 °C.
The solvent was evaporated under reduced pressure, and the
residue obtained was purified by silica gel column chroma-
tography using hexanes-ethyl acetate (1:2, v/v or 1:3, v/v) as
eluent to afford the respective title compound 14a -v in 8-45%
yield. Some physical and spectroscopic data for 14a -v are
listed below.
6-Met h oxy-3-(4-m et h a n esu lfon ylp h en yl)-4-(4-flu or o-
p h en yl)p yr a n -2-on e (14g). The product was obtained as a
solid by condensation of 9b with 11d in the presence of
triethylamine (0.05 g, 14%): mp 148-149 °C; IR (KBr): 1720
-
1
1
(CdO), 1315, 1150 (SO ) cm ; H NMR (CDCl ): δ 3.03 (s,
2
3
3H, SO CH ), 4.04 (s, 3H, OCH ), 5.56 (s, 1H, pyranone H-5),
2
3
3
6.93 (dd, J 3 ) 8.4, J
3
) 8.4 Hz, 2H, 4-fluorophenyl H-3,
HH
FH
H-5), 7.07 (dd, J 3 ) 8.4, J 4 ) 5.2 Hz, 2H, 4-fluorophenyl
HH
FH
H-2, H-6), 7.33 (d, J ) 8.2 Hz, 4-methanesulfonylphenyl H-2,
H-6), 7.78 (d, J ) 8.2 Hz, 2H, 4-methanesulfonylphenyl H-3,
H-5). Anal. (C19H15FO S): C, H.
5
6
-Meth yl-3-(4-m eth a n esu lfon ylph en yl)-4-ph en ylp yr a n -
-on e (14a ). The product was obtained as a solid by condensa-
tion of 9a with 11a in the presence of triethylamine (0.03 g,
2
6-Eth oxy-3-(4-m eth an esu lfon ylph en yl)-4-ph en ylpyr an -
2-on e (14h ). The product was obtained as a solid by condensa-
tion of 9a with 11e in the presence of triethylamine (0.06 g,
16%): mp 174-176 °C; IR (KBr): 1719 (CdO), 1310, 1145
9
cm
SO
2
%): mp 140-141 °C; IR (KBr): 1710 (CdO), 1306, 1150 (SO )
-
1
1
;
H NMR (CDCl
), 6.24 (s, 1H, pyranone H-5), 7.04-7.07 (m, 2H, phenyl
3
): δ 2.38 (s, 3H, CH
3
), 3.02 (s, 3H,
-
1
1
2
CH
3
2
(SO ) cm ; H NMR (CDCl ): δ 1.46 (t, J ) 7.0 Hz, 3H,
3
H-2, H-6), 7.22-7.31 (m, 3H, phenyl H-3, H-4, H-5), 7.36 (d,
OCH CH ), 3.02 (s, 3H, SO CH ), 4.32 (q, J ) 7.0 Hz, 2H,
2
3
2
3
J ) 8.5 Hz, 4-methanesulfonylphenyl H-2, H-6), 7.78 (d, J )
OCH CH ), 5.57 (s, 1H, pyranone H-5), 7.07-7.08 (m, 2H,
2
3
8
H
.5 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5). Anal. (C19
-
phenyl H-2, H-6), 7.18-7.31 (m, 3H, phenyl H-3, H-4, H-5),
7.35 (d, J ) 8.5 Hz, 4-methanesulfonylphenyl H-2, H-6), 7.74
16
O
4
S): C, H.
1
3
6
-Meth yl-3-(4-m eth an esu lfon ylph en yl)-4-(4-flu or oph en -
(d, J ) 8.5 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5);
NMR (CDCl ): δ 14.68 (OCH CH ), 44.51 (SO CH ), 65.73
(OCH CH ), 107.24 (pyranone C-5), 112.71 (pyranone C-3),
C
yl)p yr a n -2-on e (14b). The product was obtained as a solid
by condensation of 9b with 11a in the presence of triethyl-
amine (0.03 g, 8%): mp 156-158 °C; IR (KBr): 1712 (CdO),
3
2
3
2
3
2
3
126.80 (phenyl C-3, C-5), 128.39 and 128.67 (phenyl C-2, C-6;
4-methanesulfonylphenyl C-2, C-6), 129.21 (phenyl C-4), 132.09
(4-methanesulfonylphenyl C-3, C-5), 137.42 (phenyl C-1),
138.68 (4-methanesulfonylphenyl C-1), 140.45 (4-methane-
sulfonylphenyl C-4), 159.01 (pyranone C-4), 160.57 (pyranone
-
1 1
1
3
J
(
7
313, 1152 (SO
2
) cm ; H NMR (CDCl
CH ), 6.20 (s, 1H, pyranone H-5), 6.94 (dd,
HH ) 8.4, J FH ) 8.4 Hz, 2H, 4-fluorophenyl H-3, H-5), 7.05
3
): δ 2.38 (s, 3H, CH
3
),
.03 (s, 3H, SO
2
3
3
3
dd, J 3HH ) 8.4, J 4FH ) 5.2 Hz, 2H, 4-fluorophenyl H-2, H-6),
.32 (d, J ) 8.2 Hz, 4-methanesulfonylphenyl H-2, H-6), 7.70
d, J ) 8.2 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5). Anal.
S): C, H.
-Eth yl-3-(4-m eth a n esu lfon ylp h en yl)-4-p h en ylp yr a n -
-on e (14c). The product was obtained as a solid by condensa-
tion of 9a with 11b in the presence of triethylamine (0.14 g,
C-6), 162.75 (pyranone C-2); HRMS m/z calcd for C20
370.08749, found 370.08729. Anal. (C20 S) C, H.
-E t h oxy-3-(4-m e t h a n e su lfon ylp h e n yl)-4-(4-flu or o-
18 5
H O S,
(
(
H
18
O
5
:
19 4
C H15FO
6
6
p h en yl)p yr a n -2-on e (14i). The product was obtained as a
solid by condensation of 9b with 11e in the presence of
triethylamine (0.08 g, 20%): mp 154-156 °C; IR (KBr): 1719
2
-
1
1
3
(
CH
SO
8.3%): mp 172-174 °C; IR (KBr): 1709 (CdO), 1313, 1152
(CdO), 1312, 1146 (SO
J ) 7.0 Hz, 3H, OCH CH
7.0 Hz, 2H, OCH CH ), 5.55 (s, 1H, pyranone H-5), 6.95 (dd,
2
) cm ; H NMR (CDCl
3
): δ 1.49 (t,
-
1
1
SO
2
) cm
CH ), 2.62 (q, J ) 7.3 Hz, 2H, CH
CH ), 6.22 (s, 1H, pyranone H-5), 7.04-7.08 (m, 2H, phenyl
;
H NMR (CDCl
3
): δ 1.30 (t, J ) 7.3 Hz, 3H,
2
3
), 3.03 (s, 3H, SO CH ), 4.38 (q, J )
2
3
2
3
2
CH ), 3.02 (s, 3H,
3
2
3
3
3
2
3
J HH ) 8.3, J FH ) 8.3 Hz, 2H, 4-fluorophenyl H-3, H-5), 7.08
(dd, J 3HH ) 8.3, J 4FH ) 5.2 Hz, 2H, 4-fluorophenyl H-2, H-6),
7.33 (d, J ) 8.5 Hz, 4-methanesulfonylphenyl H-2, H-6), 7.78
(d, J ) 8.5 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5). Anal.
H-2, H-6), 7.22-7.33 (m, 3H, phenyl H-3, H-4, H-5), 7.35 (d,
J ) 8.5 Hz, 4-methanesulfonylphenyl H-2, H-6), 7.77 (d, J )
8
H
.5 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5). Anal. (C20-
18
O
4
S): C, H.
5 :
(C20H17FO S) C, H.
6
-Isop r op yl-3-(4-m eth a n esu lfon ylp h en yl)-4-p h en ylp y-
6-Isop r op yloxy-3-(4-m eth a n esu lfon ylp h en yl)-4-p h en -
ylp yr a n -2-on e (14j). The product was obtained as a solid by
condensation of 9a with 11f in the presence of triethylamine
(0.10 g, 24%): mp 185-187 °C; IR (KBr): 1720 (CdO), 1319,
r a n -2-on e (14d ). The product was obtained by condensation
of 9a with 11c in the presence of triethylamine (0.05 g, 14%):
mp 174-175 °C; IR (KBr): 1703 (CdO), 1307, 1152 (SO
H NMR (CDCl
-1
2
) cm
], 2.86-
), 6.21 (s, 1H,
;
1
-1 1
3
): δ 1.34 [d, J ) 7.0 Hz, 6H, CH(CH
], 3.03 (s, 3H, SO CH
3
)
2
1140 (SO
2
) cm ; H NMR (CDCl
3
): δ 1.46 [d, J ) 7.0 Hz, 6H,
), 5.06-5.13 [m, 1H, OCH-
2
.91 [m, 1H, CH(CH
3
)
2
2
3
OCH(CH
3
)
2
], 3.02 (s, 3H, SO CH
2
3

4
880 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23
Praveen Rao et al.
(
CH
3
)
2
], 5.58 (s, 1H, pyranone H-5), 7.04-7.08 (m, 2H, phenyl
6-(4-Ch lor oben zyloxy)-3-(4-m eth a n esu lfon ylp h en yl)-4-
(4-flu or op h en yl)p yr a n -2-on e (14q). The product was ob-
tained as a solid by condensation of 9b with 11i in the presence
of triethylamine (0.07 g, 14%): mp 173-174 °C; IR (KBr):
H-2, H-6), 7.20-7.32 (m, 3H, phenyl H-3, H-4, H-5), 7.32 (d,
J ) 8.5 Hz, 4-methanesulfonylphenyl H-2, H-6), 7.75 (d, J )
8
H
.5 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5). Anal. (C21-
-
1 1
20
O
5
S): C, H.
1722 (CdO), 1310, 1148 (SO ) cm ; H NMR (CDCl ): δ 3.03
2
3
6
-Isop r op yloxy-3-(4-m eth a n esu lfon ylp h en yl)-4-(4-flu o-
(s, 3H, SO
2
CH
3
), 5.32 (s, 2H, 4-Cl-C
6
H
4
-CH
2
O), 5.63 (s, 1H,
3
3
r op h en yl)p yr a n -2-on e (14k ). The product was obtained as
a solid by condensation of 9b with 11f in the presence of
triethylamine (0.09 g, 21%): mp 180-181 °C; IR (KBr): 1722
pyranone H-5), 6.94 (dd, J HH ) 8.5, J FH ) 8.5 Hz, 2H,
4-fluorophenyl H-3, H-5), 7.05 (dd, J 3 ) 8.5, J 4 ) 5.2 Hz,
HH
FH
2H, 4-fluorophenyl H-2, H-6), 7.32 (d, J ) 8.5 Hz, 4-methane-
sulfonylphenyl H-2, H-6), 7.41 (d, J ) 8.5 Hz, 2H, 4-chloro-
phenyl H-2, H-6), 7.44 (d, J ) 8.5 Hz, 2H, 4-chlorophenyl, H-3,
H-5), 7.79 (d, J ) 8.5 Hz, 2H, 4-methanesulfonylphenyl H-3,
-
1
1
(
CdO), 1310, 1150 (SO
2
) cm ; H NMR (CDCl
], 3.03 (s, 3H, SO CH
], 5.55 (s, 1H, pyranone H-5), 6.94 (dd,
HH ) 8.5, J FH ) 8.5 Hz, 2H, 4-fluorophenyl H-3, H-5), 7.06
3
): δ 1.46 [d,
3
J ) 6.1 Hz, 6H, OCH(CH
[
J
(
7
(
(
3
)
2
2
), 5.06-5.13
3 2
m, 1H, OCH(CH )
3
3
H-5). Anal. (C25
5
H18ClFO S): C, H.
dd, J 3HH ) 8.5, J 4FH ) 5.2 Hz, 2H, 4-fluorophenyl H-2, H-6),
.33 (d, J ) 8.2 Hz, 4-methanesulfonylphenyl H-2, H-6), 7.78
d, J ) 8.2 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5). Anal.
S): C, H.
-ter t-Bu toxy-3-(4-m eth an esu lfon ylph en yl)-4-ph en ylpy-
6
-Meth ylth io-3-(4-m eth an esu lfon ylph en yl)-4-ph en ylpy-
r a n -2-on e (14r ). The product was obtained as a solid by
condensation of 9a with 11j in the presence of triethylamine
21 5
C H19FO
6
(
1
(
2
7
0.14 g, 34.3%): mp 207-208 °C; IR (KBr): 1725 (CdO), 1308,
-1 1
145 (SO
2
) cm ; H NMR (CDCl
3
): δ 2.6 (s, 3H, SCH
3
), 3.02
r a n -2-on e (14l). The product was obtained as a solid by
condensation of 9a with 11g in the presence of triethylamine
(
1
3
s, 3H, SO
2
CH ), 6.29 (s, 1H, pyranone H-5), 7.05-7.07 (m,
3
H, phenyl H-2, H-6), 7.22-7.31 (m, 3H, phenyl H-3, H-4, H-5),
.33 (d, J ) 8.2 Hz, 4-methanesulfonylphenyl H-2, H-6), 7.76
0.10 g, 25%): mp 129-131 °C; IR (KBr): 1719 (CdO), 1310,
146 (SO
.02 (s, 3H, SO
-
1 1
2
) cm ; H NMR (CDCl
3
): δ 1.63 [s, 9H, OC(CH
3 3
) ],
(
d, J ) 8.2 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5). Anal.
‚1/2H O): C, H.
-Eth ylth io-3-(4-m eth a n esu lfon ylp h en yl)-4-p h en ylp y-
2
CH ), 5.68 (s, 1H, pyranone H-5), 7.04-7.07
3
(C
19
H
16
O
4
S
2
2
(
m, 2H, phenyl H-2, H-6), 7.21-7.31 (m, 3H, phenyl H-3, H-4,
H-5), 7.38 (d, J ) 8.5 Hz, 4-methanesulfonylphenyl H-2, H-6),
.75 (d, J ) 8.5 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5).
Anal. (C22 S): C, H.
-ter t-Bu t oxy-3-(4-m et h a n esu lfon ylp h en yl)-4-(4-flu o-
6
r a n -2-on e (14s). The product was obtained as a solid by
condensation of 9a with 11k in the presence of triethylamine
7
22 5
H O
(
1
0.06 g, 15%): mp 175-176 °C; IR (KBr): 1718 (CdO), 1314,
6
-
1 1
153 (SO
CH
), 6.35 (s, 1H, pyranone H-5), 7.04-7.07 (m, 2H, phenyl
2
) cm ; H NMR (CDCl
3
): δ 1.46 (t, J ) 7.3 Hz, 3H,
r op h en yl)p yr a n -2-on e (14m ). The product was obtained as
a solid by condensation of 9b with 11g in the presence of
triethylamine (0.09 g, 18%): mp 132-133 °C; IR (KBr): 1722
(
9
SCH
CH
2
3
), 3.03 (s, 3H, SO CH ), 3.15 (q, J ) 7.3 Hz, 2H, SCH -
2
3
2
3
-
1
1
H-2, H-6), 7.21-7.31 (m, 3H, phenyl H-3, H-4, H-5), 7.35 (d,
J ) 8.5 Hz, 4-methanesulfonylphenyl H-2, H-6), 7.78 (d, J )
CdO), 1310, 1152 (SO
H, OC(CH ], 3.01 (s, 3H, SO
2
) cm ; H NMR (CDCl
3
): δ 1.55 [s,
3
)
3
2
CH ), 5.56 (s, 1H, pyranone
3
3
3
13
H-5), 6.95 (dd, J HH ) 8.5, J FH ) 8.5 Hz, 2H, 4-fluorophenyl
H-3, H-5), 7.07 (dd, J HH ) 8.5, J 4FH ) 5.2 Hz, 2H, 4-fluoro-
phenyl H-2, H-6), 7.25 (d, J ) 8.2 Hz, 4-methanesulfonylphenyl
H-2, H-6), 7.70 (d, J ) 8.2 Hz, 2H, 4-methanesulfonylphenyl
8.5 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5); C NMR
3
(CDCl
3
2 3 2 3 2 3
): δ 14.75 (SCH CH ), 25.78 (SCH CH ), 44.51 (SO CH ),
107.34 (pyranone C-5), 117.56 (pyranone C-3), 126.89 (phenyl
C-3, C-5), 128.40 and 128.65 (phenyl C-2, C-6; 4-methane-
sulfonylphenyl C-2, C-6), 129.34 (phenyl C-4), 131.93 (4-
methanesulfonylphenyl C-3, C-5), 136.50 (phenyl C-1), 139.18
(4-methanesulfonylphenyl C-1), 139.89 (4-methanesulfonyl-
phenyl C-4), 154.26 (pyranone C-4), 161.69 (pyranone C-6),
H-3, H-5). Anal. (C22
5
H21FO S): C, H.
6
-Isobu toxy-3-(4-m eth a n esu lfon ylp h en yl)-4-p h en ylp y-
r a n -2-on e (14n ). The product was obtained as a solid by
condensation of 9a with 11h in the presence of triethylamine
(
1
0.09 g, 22%): mp 156-158 °C; IR (KBr): 1720 (CdO), 1311,
162.20 (pyranone C-2). Anal. (C20
18 4 2
H O S ): C, H.
-
1 1
150 (SO
CH(CH
H, SO CH ), 4.03 [d, J ) 6.7 Hz, 2H, OCH
2
) cm ; H NMR (CDCl
3
): δ 1.05 [d, J ) 6.7 Hz, 6H,
CH(CH ], 3.01 (s,
CH(CH ], 5.58
6
-Eth ylth io-3-(4-m eth a n esu lfon ylp h en yl)-4-(4-flu or o-
OCH
3
(
7
4
4
2
3
)
2
], 2.11-2.19 [m, 1H, OCH
2
3 2
)
p h en yl)p yr a n -2-on e (14t). The product was obtained as a
solid by condensation of 9b with 11k in the presence of
triethylamine (0.07 g, 17%): mp 171-172 °C; IR (KBr): 1716
2
3
2
3 2
)
s, 1H, pyranone H-5), 7.05-7.09 (m, 2H, phenyl H-2, H-6),
.20-7.30 (m, 3H, phenyl H-3, H-4, H-5), 7.34 (d, J ) 8.0 Hz,
-methanesulfonylphenyl H-2, H-6), 7.75 (d, J ) 8.0 Hz, 2H,
-methanesulfonylphenyl H-3, H-5). Anal. (C22
-1 1
(
7
CdO), 1313, 1152 (SO
.3 Hz, 3H, SCH CH ), 3.04 (s, 3H, SO
Hz, 2H, SCH CH ), 6.32 (s, 1H, pyranone H-5), 6.96 (dd,
HH ) 8.5, J FH ) 8.5 Hz, 2H, 4-fluorophenyl H-3, H-5), 7.07
dd, J 3HH ) 8.5, J 4FH ) 5.2 Hz, 2H, 4-fluorophenyl H-2, H-6),
.35 (d, J ) 8.5 Hz, 4-methanesulfonylphenyl H-2, H-6), 7.80
d, J ) 8.5 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5). Anal.
): C, H.
-n -P r op ylt h io-3-(4-m et h a n esu lfon ylp h en yl)-4-p h en -
2
) cm ; H NMR (CDCl
3
) δ 1.46 (t, J )
2
3
2
CH ), 3.15 (q, J ) 7.3
3
22 5
H O S): C, H.
2
3
6
-Isobu toxy-3-(4-m eth a n esu lfon ylp h en yl)-4-(4-flu or o-
3
3
J
(
7
p h en yl)p yr a n -2-on e (14o). The product was obtained as a
solid by condensation of 9b with 11h in the presence of
triethylamine (0.10 g, 24%): mp 138-139 °C; IR (KBr): 1719
(
(
-
1
1
(
CdO), 1310, 1150 (SO
J ) 6.7 Hz, 6H, OCH CH(CH
CH(CH ], 3.03 (s, 3H, SO CH
OCH CH(CH ], 5.55 (s, 1H, pyranone H-5), 6.95 (dd, J HH
.5, J FH ) 8.5 Hz, 2H, 4-fluorophenyl H-3, H-5), 7.07 (dd,
2
) cm ; H NMR (CDCl
], 2.12-2.18 [m, 1H, OCH
), 4.06 [d, J ) 6.7 Hz, 2H,
3
): δ 1.06 [d,
20 4 2
C H17FO S
2
3
)
2
2
-
6
3
)
2
2
3
3
ylp yr a n -2-on e (14u ). The product was obtained as a solid by
condensation of 9a with 11l in the presence of triethylamine
(0.14 g, 32%): mp 158-160 °C; IR (KBr): 1727 (CdO), 1308,
2
3
)
2
)
3
8
J
3
4
HH ) 8.5, J FH ) 5.2 Hz, 2H, 4-fluorophenyl H-2, H-6), 7.32
-
1 1
1
157 (SO
SCH CH
SO CH ), 3.09 (t, J ) 7.3 Hz, 2H, SCH
pyranone H-5), 7.04-7.06 (m, 2H, phenyl H-2, H-6), 7.22-7.31
m, 3H, phenyl H-3, H-4, H-5), 7.34 (d, J ) 8.2 Hz, 4-meth-
anesulfonylphenyl H-2, H-6), 7.76 (d, J ) 8.2 Hz, 2H, 4-meth-
anesulfonylphenyl H-3, H-5); 13C NMR (CDCl
): δ 13.28
2
) cm ; H NMR (CDCl
3
): δ 1.06 (t, J ) 7.3 Hz, 3H,
CH CH ), 3.02 (s, 3H,
CH CH ), 6.35 (s, 1H,
(
d, J ) 8.5 Hz, 4-methanesulfonylphenyl H-2, H-6), 7.79 (d,
J ) 8.5 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5). Anal.
S): C, H.
-(4-Ch lor oben zyloxy)-3-(4-m eth a n esu lfon ylp h en yl)-4-
2
2
CH ), 1.56-1.87 (m, 2H, SCH
3
2
2
3
22 5
(C H21FO
2
3
2
2
3
6
(
p h en ylp yr a n -2-on e (14p ). The product was obtained as a
solid by condensation of 9a with 11i in the presence of
triethylamine (0.08 g, 16%): mp 157-159 °C; IR (KBr): 1724
3
-
1
1
(SCH CH CH ), 22.86 (SCH CH CH ), 33.24 (SCH CH CH ),
(
3
CdO), 1310, 1146 (SO
H, SO CH ), 5.32 (s, 2H, 4-Cl-C
pyranone H-5), 7.03 (m, 2H, phenyl H-2, H-6), 7.13-7.24 (m,
2
) cm ; H NMR (CDCl
3
): δ 3.02 (s,
2
2
3
2
2
3
2
2
3
4
4.51 (SO
2
CH
3
), 107.24 (pyranone C-5), 117.40 (pyranone C-3),
2
3
6
H
4
-CH O), 5.66 (s, 1H,
2
126.93 (phenyl C-3, C-5), 128.40 and 128.80 ((phenyl C-2, C-6;
4-methanesulfonylphenyl C-2, C-6), 129.35 (phenyl C-4), 131.94
(4-methanesulfonylphenyl C-3, C-5), 136.44 (phenyl C-1),
139.02 (4-methanesulfonylphenyl C-1), 139.91 (4-methane-
sulfonylphenyl C-4), 154.32 (pyranone C-4), 161.92 (pyranone
3
4
4
H, phenyl H-3, H-4, H-5), 7.27 (d, 2H, J ) 8.4 Hz, 2H,
-methanesulfonylphenyl H-2, H-6), 7.31 (d, J ) 8.5 Hz, 2H,
-chlorophenyl H-2, H-6), 7.37 (d, J ) 8.5 Hz, 2H, 4-chloro-
phenyl H-3, H-5), 7.75 (d, J ) 8.5 Hz, 2H, 4-methanesulfonyl-
phenyl H-3, H-5). Anal. (C25 S): C, H.
H
19ClO
5
20 4 2
C-6), 162.28 (pyranone C-2). Anal. (C21H O S ): C, H.

Selective Cyclooxygenase-2 Inhibitors
-Isop r op ylth io-3-(4-m eth a n esu lfon ylp h en yl)-4-p h en -
ylp yr a n -2-on e (14v). The product was obtained by condensa-
tion of 9a with 11m in the presence of triethylamine (0.19 g,
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 23 4881
6
enzyme complex was subjected to docking using the Affinity
command in the Docking module of Insight II after defining
subsets of the enzyme such that residues within 10 Å of the
ligand were allowed to relax, while the remainder of the
enzyme residues were fixed. The consistent valence force field
(CVFF) was employed for all docking purposes. The optimal
binding orientation of the ligand-enzyme assembly obtained
after docking was further minimized for 1000 iterations using
the conjugate gradient method until a convergence of 0.001
kcal/mol Å was reached. The ligand-enzyme assembly was
then subjected to a molecular dynamics (MD) simulation using
the Discover module Version 2.98 at a constant temperature
of 300 K with a 200-step equilibration for over 5000 iterations
and a time step of 1 fs using a distance dependent dielectric
constant 4r.
4
4.5%): mp 164-166 °C; IR (KBr): 1721 (CdO), 1310, 1160
-
1 1
(
(
6
SO
CH
.39 (s, 1H, pyranone H-5), 7.02-7.05 (m, 2H, phenyl H-2,
2
) cm ; H NMR (CDCl
3
): δ 1.42 [d, J ) 6.7 Hz, 6H, SCH-
3
)
2
], 3.01 (s, 3H, SO CH
2
3
), 3.83-3.92 [m, 1H, SCH(CH ],
3 2
)
H-6), 7.20-7.29 (m, 3H, phenyl H-3, H-4, H-5), 7.33 (d, J )
8
8
.5 Hz, 4-methanesulfonylphenyl H-2, H-6), 7.75 (d, J )
.5 Hz, 2H, 4-methanesulfonylphenyl H-3, H-5). Anal. (C21
): C, H.
Cyclooxygen a se In h ibition Stu d ies. All compounds de-
-
20 4 2
H O S
scribed herein were tested for their ability to inhibit COX-1
and COX-2 using a COX-(ovine) inhibitor screening kit (Cata-
log No. 560101, Cayman Chemical, Ann Arbor, MI) according
to the manufacturer’s instructions. Cyclooxygenase catalyzes
the first step in the biosynthesis of arachidonic acid (AA) to
Ack n ow led gm en t. We are grateful to the Canadian
Institutes of Health Research (MOP-14712) for financial
support of this research and to Rx & D-HRF/CIHR for
a graduate scholarship (to P.R.) The technical assistance
of C.-A. McEwen in performing the antiinflammatory
and analgesic assays is gratefully acknowledged.
2 2
PGH . PGF2R, produced from PGH by reduction with stannous
chloride, is measured by enzyme immunoassay (ACE competi-
tive EIA). Stock solutions of test compounds were dissolved
in a minimum volume of DMSO. Briefly, to a series of supplied
reaction buffer solutions (960 µL, 0.1 M Tris-HCl pH 8.0
containing 5 mM EDTA and 2 mM phenol) with either COX-1
or COX-2 (10 µL) enzyme in the presence of heme (10 µL) was
added 10 µL of various concentrations of test drug solutions
Refer en ces
(
0.001, 0.01, 0.1, 1, 10, 100, and 500 µM in a final volume of 1
mL). These solution were incubated for a period of 2 min at
7 °C after which 10 µL of AA (100 µM) was added, and the
COX reaction was stopped by the addition of 50 µL of 1 M
HCl after 2 min. PGF2R, produced from PGH by reduction with
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