Synthesis and Selective Cyclooxygenase-2 Inhibitory Activity of a Series of Novel, Nitric Oxide Donor-Containing Pyrazoles

Article abstract of DOI:10.1021/jm030276s

The synthesis of a series of novel pyrazoles containing a nitrate (ONO ₂) moiety as a nitric oxide (NO)-donor functionality is reported. Their COX-1 and COX-2 inhibitory activities in human whole blood are profiled. Our data demonstrate that py

Full text of DOI:10.1021/jm030276s

2180
J . Med. Chem. 2004, 47, 2180-2193
Articles
Syn th esis a n d Selective Cyclooxygen a se-2 In h ibitor y Activity of a Ser ies of
Novel, Nitr ic Oxid e Don or -Con ta in in g P yr a zoles†
Ramani R. Ranatunge,* Michael Augustyniak,‡ Upul K. Bandarage, Richard A. Earl, J ames L. Ellis,
David S. Garvey, David R. J anero, L. Gordon Letts, Allison M. Martino, Madhavi G. Murty,
Stewart K. Richardson, J oseph D. Schroeder, Matthew J . Shumway, S. William Tam, A. Mark Trocha, and
Delano V. Young
NitroMed Inc., 12 Oak Park Drive, Bedford, Massachusetts 01730
Received J une 4, 2003
The synthesis of a series of novel pyrazoles containing a nitrate (ONO2) moiety as a nitric
oxide (NO)-donor functionality is reported. Their COX-1 and COX-2 inhibitory activities in
human whole blood are profiled. Our data demonstrate that pyrazole ring substituents play
an important role in COX-2 selective inhibition, such that a cycloalkyl pyrazole (6b) was found
to be a potent and selective COX-2 inhibitor. Other modifications at the 3 position of the central
pyrazole ring (17b, 23b, 26b-I) enhanced COX-2 inhibitory potency. Among the pyrazoles
synthesized, the oxime (23b) was identified as the most potent COX-2 selective inhibitor.
Accordingly, 23b was profiled pharmacologically in the rat after oral administration and shown
to possess potent antiinflammatory activity in the carrageenan-induced air-pouch model and
less gastric toxicity than a standard COX-2 inhibitor when administered with background
aspirin treatment. We suggest that the enhanced gastric tolerance of an NO-donor COX-2
selective inhibitor has the potential to augment the clinical profile of this drug class.
In tr od u ction
Yet COX-2 selective inhibitors are not without
limitations.16a At higher doses and/or with long-term
use, COX-2 selective inhibitors may lose selectivity and
inhibit COX-1 in vivo. Recent evidence points to a
homeostatic role for at least some COX-2-generated
PGs. Potential clinical limitations of long-term COX-2
inhibitor therapy include ulcer exacerbation in high-risk
patients, delayed gastroduodenal ulcer healing, kidney
toxicity, and a pro-thrombotic prostacyclin (PGI2)
deficiency.16-19 Particularly noteworthy in light of the
now routine use of low-dose aspirin in the prophylaxis
of cardiovascular disease and acute coronary syndromes,
the gastric tolerability of COX-2 selective inhibitors is
compromised in patients taking aspirin.19a
Along with prostacyclin (PGI2), nitric oxide (NO) plays
an important cytoprotective role in GI homeostasis by
helping maintain mucosal blood flow, by optimizing
mucus secretion, and by inhibiting platelet and inflam-
matory-cell activation.20-24 As an alternative to COX-2
selective inhibitors, we and others have developed a
synthetic strategy toward safer, GI-sparing NASIDs
involving the chemical coupling of a NO-donor moiety
to a nonselective NSAID.20-24 Structurally diverse NO-
releasing NSAIDs (including nitrate and nitrosothiol
derivatives of aspirin, naproxen, ketoprofen, diclofenac,
and flurbiprofen) have been characterized.20-26 Some
NO-donor NSAIDs have antiinflammatory activity com-
parable to their respective parent NSAIDs in acute
rodent models, but with less GI toxicity,20-26 and may
even promote ulcer healing.22 The intrinsic tissue-
protective and antiinflammatory properties of NO may
help reduce further the GI irritation still associated with
Nonsteroidal antiinflammatory drugs (NSAIDs) are
widely used to treat the signs and symptoms of inflam-
mation, particularly arthritic pain.1,2 NSAIDs exert
their antiinflammatory effect mainly through inhibition
of cyclooxygenases (COXs), key enzymes in prostaglan-
din (PG) biosynthesis from arachidonic acid.3-5 There
are at least two mammalian COX isoforms, COX-1 and
COX-2.6,7 Constitutive COX-1 is responsible for the
chronic, low-level production of cytoprotective PGs in
the gastrointestinal (GI) tract, whereas the main func-
tion of inducible, short-lived COX-2 is to generate PGs
in inflammatory cells. Traditional NSAIDs such as
aspirin, indomethacin, and naproxen are nonselective
in that they inhibit COX-2 and, with somewhat greater
potency, COX-1.8-11 Morbidity and mortality due to
NSAID-induced GI toxicity are significant and frequent
enough worldwide to limit the therapeutic use of this
drug class.12 Common NSAID clinical side-effects, in-
cluding GI irritation, bleeding, and ulceration, are
believed to reflect NSAID inhibition of “housekeeping”
PG production by COX-1. Indeed, the first COX-2
selective inhibitors approved for human use, Celecoxib
(Celebrex)15a and Rofecoxib (Vioxx),15b exert the benefi-
cial antiinflammatory and analgesic properties of NSAIDs
with enhancedsbut not absolutesGI tolerance.13,14
† A portion of this work was presented in poster form at the 224th
American Chemical Society National Meeting, Medicinal Chemistry
(abstract #314), Boston, MA, Aug 18-22, 2002.
* To whom correspondence should be addressed. Phone: (781) 685
9739. Fax: (781) 275 112. E-mail: rbandarage@nitromed.com.
‡ Authors appear in alphabetical order.
10.1021/jm030276s CCC: $27.50 © 2004 American Chemical Society
Published on Web 03/27/2004

COX-2 Inhibition by Nitric Oxide Donor-Containing Pyrazoles
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 9 2181
Sch em e 1a
a
(a) NaOCH3, dimethyl oxalate, toluene; (b) R1NHNH2, MeOH, H+, 60 °C; (c) LAH, THF; (d) Oxone, MeOH/H2O or mCPBA, CH2Cl2,
0 °C; (e) f.HNO3/Ac2O,CHCl3, -10 °C.
COX-2 selective inhibitors, particularly in the setting
of aspirin cardiovascular prophylaxis.27,28
reported. We have synthesized pyrazole analogues
which incorporate this arrangement of functional groups.
Furthermore, these compounds bear a nitrate group as
NO donor. The nitrate group is linked to the pyrazole
core either by a simple alkyl, alkenyl, keto, or keto
derivative tether.
We report herein the synthesis, COX inhibitory
structure-activity relationship (SAR), and biological
evaluation of a series of novel pyrazole COX-2 selective
inhibitors containing a NO-donor group.29 As compared
to routine COX-2 selective inhibitors without NO-
donating properties, the NO-donor COX-2 selective
inhibitors possess additional biological activities that
could enhance the overall clinical profile of this drug
class.
A series of 1-cycloalkyl-5-arylsufone pyrazoles was
prepared from commercially available 4-methylthio-
acetophenone, as illustrated in Scheme 1. The reaction
of dimethyl oxalate with the enolate derived from
4-methylthioacetophenone in toluene gave the dike-
toester 2 in high yield. This was condensed with
cycloalkylhydrazines in the presence of a catalytic
amount of concentrated HCl or trifluoroacetic acid to
obtain pyrazoles 3 in high yield. In most cases, the 1,3,5-
substituted pyrazole, 3-I, was formed exclusively. In
those cases where there was concurrent formation of the
1,2,4-regioisomer, 3-II, the two products were readily
separated by recrystallization. The ester group of 3-I
was reduced by lithium aluminum hydride (LAH) to
obtain the alcohols 4, which were oxidized to the
sulfones 5 with Oxone in high yield. Introduction of the
NO-donor (nitrate) group was achieved with a mixture
of fuming nitric acid and acetic anhydride in chloroform
or ethyl acetate at -10 °C to give 6 in moderate to high
yield. Those nitrates unstable to flash chromatography
were purified by recrystallization. Sulfones of pyrazole
methyl esters 7 were prepared by oxidation of 3-I with
Oxone in quantitative yield or by condensaton of 2A
with a hydrazine.
Ch em istr y
Pyrazole compounds have been identified as potent,
selective COX-2 inhibitors with good pharmacokinetic
profiles. From this knowledge base, we sought to develop
COX-2 selective pyrazoles with NO-donating capabili-
ties. In our case, incorporation of the NO-donor group
requires that the pyrazole have an appropriate func-
tionality that can be easily derivatized to a nitrate
group. For this purpose, a hydroxyl group was deemed
most appropriate for nitration. Generally, for COX-2
selective inhibitors, substitution at positions 1, 3, and
5 of the pyrazole is required. Substitution at position 4
dramatically diminishes COX-2 selectivity. Optimum
selectivity is observed with an aryl sulfonamide or
sulfone group at position 1 of the pyrazole ring, another
substituted or nonsubstituted aryl group at position 5,
and a small aliphatic moiety (such as a methyl or
trifluoromethyl group) at position 3.
The two-carbon and three-carbon homologues of 6
were synthesized as shown in Scheme 2. The alcohol 4
(Scheme 1) was subjected to Swern oxidation followed
by Wittig olefination to give 9 in good yield. Hydrobo-
ration30,31 of the terminal alkene followed by selective
The clinically approved COX-2 inhibitor Celebrex has
a 1,5- diaryl substitution and a trifluoromethyl group
at position 3. However, SAR studies of pyrazoles with
a cycloalkyl subtitution at position 1 and an aryl sulfone
substitution at position 5 have not been previously

2182 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 9
Ranatunge et al.
Sch em e 2a
a
(a) DMSO/(COCl)2, Et3N, CH2Cl2; (b) Ph3PCH3Br/BuLi; (c) BH3‚THF,H2O2,NaOH; (d) Oxone, MeOH, H2O; (e) f. HNO3/Ac2O, CHCl3;
(f) BuLi/(CH3O)2PCH2CO2CH3, THF; (g) LAH, THF; (h) Pd/H2, 50 psi.
Sch em e 3a
a
(a) Me3Al/HN(OCH3)CH3.HCl, CH2Cl2, 0 °C; (b) TBDMSO(CH2)nMgBr, THF; (c) TBAF, THF; (d) Oxone, MeOH/H2O; (e) f.HNO3/
Ac2O, CHCl3, -10 °C; (f) NH2OR2‚HCl, 15 N NaOH/EtOH.
oxidation of the sulfide with Oxone gave 11 in high yield.
Nitration of 11 was achieved as shown in Scheme 1 to
afford the ethyl nitrate 12. The propyl nitrates 17 were
synthesized from aldehydes 8 in four or five steps.
Horner-Wadsworth-Emmons olefination of 8 afforded
13 in high yield. Reduction of the ester group of 13 with
LAH followed by oxidation of the methyl sulfide gave
15. This was hydrogenated to afford 16, which was
nitrated to give 17. Alternatively, reduction of 13 with
excess LAH gave hydroxypropylpyrazole methyl sulfide
16(i), which was oxidized and then nitrated to give 17.
The syntheses of pyrazole nitrates with carbonyl
linkers are illustrated in Scheme 3. Weinreb amides 18
were synthesized from the reaction of 3-I (Scheme 1)
with N,O-dimethylhydroxylamine hydrochloride in the
presence of trimethylaluminum.32,33 Grignard reaction
of 18 with a TBDMS-protected three- or five-carbon
Grignard reagent gave 19 in good yield. The TBDMS
group of 19 was readily removed by tetrabutylammo-
nium fluoride (TBAF) to afford 20, which was oxidized
with Oxone to give sulfones 21. (A more direct conver-
sion of 19 to 21 can be achieved by simultaneous

COX-2 Inhibition by Nitric Oxide Donor-Containing Pyrazoles
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 9 2183
Sch em e 4a
a
(a) BrPh3P(CH2)2CH2OTBDMS, BuLi, THF, -78 °C; (b) BrPh3P(CH2)2CH2OTBDMS, MnO2, guanidine, Ti(OPri)4, THF, 70 °C; (c)
Oxone, MeOH/H2O; (d) f.HNO3/Ac2O, CHCl3, -10 °C or f.HNO3, CHCl3, 0 °C.
deprotection34 and oxidation in a single step using
Oxone.) Nitration of 21 afforded ketonitrates 22 in high
yield.
group by TBAF followed by nitration in a usual manner
afforded 33.
Resu lts a n d Discu ssion
Many alkyl and aryl oximes have the potential for in
vivo NO release by an as yet unknown mechanism.35
To generate a pyrazole COX-2 inhibitor with the poten-
tial to act as a bifunctional NO donor, the oximes 23
were prepared by the reaction of 22 with hydroxylamine
hydrochloride or methoxylamine hydrochloride in the
presence of 15 N NaOH (Scheme 3).
A few early compounds were evaluated as potential
COX inhibitors by using human or ovine recombinant
COX-1 and human COX-2. Subsequently, all compounds
were tested for their ability to inhibit COX-1 and COX-2
activity in human whole blood (HWB).39,40 For both of
these in vitro assays, compounds were tested against
COX-1 at 100 µM and against COX-2 at 10 and 1 µM
(Tables 1-5). For the most potent, selective COX-2
inhibitors, IC50’s were determined in the HWB assay
(Table 6). All compounds that inhibited COX-2 with
potency and high selectivity were tested in the rat
carrageenan-induced air-pouch model41,42 to index their
in vivo antiinflammatory activity (i.e., suppression of
white-cell infiltration and/or PG production) at a fixed
oral dose (45 µmol/kg) (Table 7). The most selective
COX-2 inhibitor with potent antiinflammatory activity
(23b) was further profiled in a rat gastric injury model.
Nitrates attached by three- or four-carbon alkenyl
linkers were prepared as outlined in Scheme 4. Alde-
hydes 8 (Scheme 2) were converted to a separable
mixture of Z and E alkenes 24 using a Wittig reagent36
in high yield. Alternatively, 24 could be synthesized by
a one-pot reaction involving treatment of the alcohols
4 (Scheme 1) with the same Wittig reagent in the
presence of manganese dioxide and guanidine.37 Re-
moval of the TBDMS group of 24 and oxidation of the
sulfide to a sulfone with Oxone gave the hydroxy
pyrazole 25. Nitration of 25 in the usual manner gave
the four-carbon chain alkenyl nitrates 26. The three-
carbon-containing alkenyl nitrate 27 can be prepared
from alcohol 15 (Scheme 2) in a similar manner.
In Vitr o Activity. A common feature among many
previously described COX-2 selective inhibitors is 1,5-
diaryl substitution of a central pyrazole ring. We
explored replacing the aryl substitution at the 1 position
with various cycloalkyl groups. The substitution at the
3 position, a nitroxymethyl group, was derived from the
corresponding hydroxy derivative. In vitro profiles for
these compounds as COX inhibitors are summarized in
Table 1. Cyclopentyl-substituted nitrate 6a slightly
potentiated COX-2 activity, whereas the cyclohexyl
nitrate 6b, cycloheptyl nitrate 6c or cyclooctyl nitrate
6d showed selective COX-2 inhibition at both the 1 µM
and 10 µM. Bulky and more lipophilic cycloalkyl groups
(e.g., cyclooctyl) marginally enhanced COX-1 inhibitory
activity at the 100 µM test concentration (% COX-1
Generally, sulfonamides have slightly better affinities
than sulfones for the COX-2 active site.15b Thus, we
decided to prepare the sulfonamide analogue 33 of
sulfone 22b from its methyl sulfide, as described in
Scheme 5.38 The oxidation of 19b with magnesium
monoperoxyphthalate (MMPP) gave sulfoxide 28. Treat-
ment of 28 with acetic anhydride at 120 °C caused a
Pummerer rearrangement to give the acetoxymethylthio
compound 29. Further oxidation of 29 with MMPP gave
30. Compound 30 could be converted to 31 by treatment
with NaOAc and K2CO3 followed by reaction with
hydroxylamine-O-sulfonic acid. Removal of the TBDMS

2184 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 9
Ranatunge et al.
Sch em e 5a
a
(a) MMPP, MeOH, CH2Cl2; (b) Ac2O/NaOAc, 120 °C; (c) i. NaOAC, MeOH, ii. K2CO3, MeOH iii. NH2OSO3H; (d) TBAF, THF; (e)
f.HNO3/Ac2O,CHCl3, -10 °C.
inhibition: 6a ) 0, 6b ) 35, 6c ) 35 and 6d ) 60). The
COX-inhibitory IC50’s of 6b (COX-1>100 µM; COX-2 )
0.4 µM) show that it is a very potent, highly selective
COX-2 inhibitor (Table 6).
inhibited COX-1 by 90% at 100 µM, prompting the
synthesis of 17h with a cyclohexylmethyl group at
position 1 and a three-carbon nitrate linker at position
3. The COX inhibitor profile of the cyclohexylmethyl
compound, 17h , is consistent with its corresponding one-
carbon chain analogue, 6h (% inhibition of COX-2 for
17h ) 75 and 6h ) 10 at 1 µM). This series suggests
that COX-2 inhibitory potency might be enhanced by
lengthening the carbon chain at position 3, perhaps at
the expense of COX-2 selectivity.
Next, we introduced a heteroatom into the cyclohexyl
ring of 6b to examine its potential effect upon COX-2
inhibitory potency and selectivity. As seen in Table 1,
introduction of oxygen or sulfur into the cyclohexyl ring
markedly decreased COX-2 inhibition (% COX-2 inhibi-
tion: 6b ) 80 and 6e ) 30 at 10 µM). Likewise, a
4-carbethoxy substitutant (6g) reduced COX-2 inhibi-
tory potency, as compared to 6e (6g ) 0% COX-2
inhibition at 10 µM). These results suggest that the
lipophilic character of the cyclohexyl group at position
1 contributes to COX-2 inhibitory activity. Substitution
of a spacer group (CH2) between the pyrazole center and
position 1 weakened the COX-2 inhibitory activity when
compared to 6b (e.g., % COX-2 inhibition for cyclohexyl-
methyl 6h ) 65; benzyl 6i ) 40 at 10 µM). These data
show how important the lipophilic cyclohexyl ring is to
COX-2 inhibitor potency as compared to aromatic ring
substitution. Compound 6j, in which the cycloalkyl ring
was replaced by an open alkyl chain (2,6-dimethylhept-
4-yl), did not inhibit COX-2 up to a 10 µM test
concentration and marginally inhibited COX-1 (by 15%)
at 100 µM. The lack of activity of 6e, 6f, and 6j suggests
that the active site of COX-2 is very sensitive to both
the electronic and steric properties of substitution at the
1 position.
With the aim of improving these COX-2 inhibitors and
retaining the 3-position nitrated linker, we varied the
nature of the carbon chain. First, we considered a series
of pyrazole nitrates (22b, 22k -r ) containing carbonyl
linkers (Scheme 3). Synthesis and biological evaluation
of such carbonyl pyrazoles have not been reported
previously. Aryl substituted nitrates demonstrated very
good COX-2 inhibition (Table 3). However, most of the
phenyl or substituted phenyl pyrazoles (22k -r ) showed
somewhat greater COX-1 inhibitory activity compared
with 22b. Among these carbonyl-pyrazole derivatives,
the N-cyclohexyl substituent (22b) was more potent and
selective than the phenyl or substituted phenyl deriva-
tives. Changing the 4-fluoro (22o) substituent to 4-chlo-
ro (22p ) or 4-bromo (22q) compromised COX-2 selec-
tivity, and a 4-cyano substituent (22r ) clearly diminished
COX-2 inhibitory potency. Replacing the 4-methyl (22l)
substituent with a 4-trifluoromethyl group (22m ) did
not alter COX-2 selectivity but reduced potency. 4-Meth-
oxy substitution yielded the more potent, less COX-2
selective compound 22n (IC50 for COX-1 and COX-2, 1.5
µM and 2.5 µM, respectively) (Table 6). Elongation of
the nitrate-containing carbonyl chain from three (22b)
to five (22b-i) carbons did not significantly reduce
COX-2 inhibitory potency (% inhibition of COX-2 for 22b
) 80 and 22b-i ) 75 at 10 µM).
The effect of the chain length at the 3 position of the
pyrazole ring was next examined. Lengthening the
chain from one to three carbons enhanced COX-2
inhibition (% COX-2 inhibition: 6b ) 80; 12b ) 95; and
17b ) 100 at 10 µM) (Table 2). Even at 1 µM, these
compounds were appreciable COX-2 inhibitors (Table
2). However, 17b showed limited selectivity in that it

COX-2 Inhibition by Nitric Oxide Donor-Containing Pyrazoles
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 9 2185
Ta ble 1. In Vitro Enzyme and Human Whole Blood COX-1
and COX-2 Inhibition by Pyrazole Nitrate and Alcohol
Derivatives
Ta ble 2. In Vitro Enzyme and Human Whole Blood COX-1
and COX-2 Inhibition by Pyrazole Nitrate and Alcohol
Derivatives
% inhibition HWBa
% inhibition HWBa
COX-1
COX-2
COX-1
COX-2
compd
R1
cyclopentyl
R′
100 µM 10 µM 1 µM
compd
R1
R2
n
100 µM 10 µM 1 µM
6a b
5a
NO2
H
NO2
H
NO2
H
NO2
H
NO2
H
NO2
H
0
40
35
25
35
40
60
35
10
10
nd
nd
20
-100 -125
-75 -125
6b
cyclohexyl
NO2
NO2
H
NO2
H
1
1
1
2
2
3
3
1
1
3
3
35
40
25
0
80
100
35
95
35
100
90
65
40
100
90
45
45
10
45
0
75
45
10
0
75
45
50
90
75
40
6bb
5b
6b
cyclohexyl
cycloheptyl
cyclooctyl
80
35
90
25
90
75
30
10
0
45
10
60
10
50
35
10
0
5bb
6c
12bb
11bb
17b
16b
6h
cyclohexyl
cyclohexyl
35
90
90
25
65
90
90
nd
80
75
0
5c
6d
5d
NO2
H
cyclohexylmethyl NO2
6eb
5eb
6fb
5fb
6g
perhydro-2H-
pyran-4-yl
1,1-dioxothian-4-yl
5h
17h
16h
H
cyclohexylmethyl NO2
H
10
0
10
0
Celecoxib
100
100
100
100
Celecoxibb
2-[1-(ethoxycarbonyl)- NO2
4-piperidyl]
H
0
Rofecoxib
Rofecoxibb
5g
6h b
5h b
6i
5i
6j
0
25
65
55
25
15
0
nd
80
75
0
10
65
40
40
15
0
25
100
100
100
100
10
10
0
cyclohexylmethyl
NO2
H
NO2
H
a
Percent inhibition of COX-1 (100 µM) or COX-2 (10 and 1 µM)
in human whole blood. Assays were performed in duplicate.
benzyl
20
10
15
10
50
90
75
40
b
Average % inhibition of two donors. Percent inhibition of recom-
binant COX-1 (100 µM) or COX-2 (10 and
determined.
1 µM). nd, not
2,6-dimethylhept-4-yl NO2
5j
H
Celecoxib
selectivities. The Z isomers (e.g., 26b-I, 26k -I) were
generally more potent and selective than the corre-
sponding E series (e.g., 26b-II, 26k -II, 27b-II, 27h -II).
Lengthening the carbon chain of 27b-II by one carbon
enhanced the COX-2 potency and selectivity of the E
isomers (% inhibition of COX-2 for 26b-II ) 90 and 27b-
II ) 45 at 10 µM). The compound 26b-I emerged as the
most potent and selective compound in the alkene
series: its IC50’s for COX-1 and COX-2 inhibition, 1000
µM and 0.5 µM, respectively, demonstrate a 2000-fold
COX-2 selectivity (Table 6).
In Vivo Activity. Ra t Ca r r a geen a n -In d u ced Air
P ou ch Mod el. As active compounds in the carbonyl
series, we chose 22b, 22l, 22n , and 22o for in vivo
pharmacological evaluation as antiinflammatory agents
(Table 7). To this intent, we utilized the rat carra-
geenan-ionduced air-pouch model, since exudate PG
production in this model is COX-2 driven. In this
inflammation model, compound 22n proved most potent,
with 78% inhibition of PGE2 formation and 43% inhibi-
tion of white-cell infiltration at an oral dose of 45 µmol/
kg. However, 22n showed poor selectivity (IC50’s for
COX-1/COX-2 ) 1.5 µM/2.5 µM) (Table 6). Among
selective pyrazole carbonyl derivatives, only compounds
22o and 22b showed good antiinflammatory activity.
Both inhibited PGE2 production by 45% at 45 µmol/kg.
As the best COX-2 selective inhibitor in the pyrazole-
alkene series, 26b-I was also evaluated in the air pouch
inflammation model. It showed moderate antiinflam-
matory activity, with 25% inhibition of PGE2 formation
and 17% inhibition of white-cell infiltration at an oral
dose of 45 µmol/kg (Table 7).
Celecoxibb
Rofecoxib
Rofecoxibb
a
Percent inhibition of COX-1 (100 µM) or COX-2 (10 and 1 µM)
in human whole blood. Assays were performed in duplicate.
b
Average % inhibition of two donors. Percent inhibition of recom-
binant COX-1 (100 µM) or COX-2 (10 and
determined.
1 µM). nd, not
On the basis of the COX-2 potency and selectivity
demonstrated in the carbonyl series (Table 3), compound
22b was selected for further modification. It has been
reported that replacement of the methyl sulfone moiety
with a sulfonamide group generated more potent COX-2
inhibitors with enhanced in vivo antiinflammatory
activity, albeit with some loss of COX-2 selectivity.15b
Accordingly, we synthesized the carbonyl pyrazole-
sulfonamide, 33 (Scheme 5), which was found to be less
potent (15% inhibition of COX-2 at 10 µM and 30%
inhibition of COX-1 at 100 µM) than 22b in the HWB
COX assay. The corresponding alcohol analogue (32) of
33 had limited COX-2 inhibitory activity (10% inhibition
of COX-2 at 10 µM and 30% inhibition of COX-1 at 100
µM).
Further modification in the pyrazole carbonyl series
produced a series of pyrazole oxime nitrates (Table 4).
The hydroxime 23b and methoximes 23b-ii showed
good COX-2 inhibitory potency (% inhibition of COX-2
for 23b ) 100 and 23b-ii ) 90 at 10 µM) and
selectivity. Lengthening the carbon chain from three
(e.g., 23b) to five (e.g., 23b-i) carbons diminished COX-2
inhibitory activity.
Pyrazole nitrates containing an alkene linker at
position 3 were next evaluated as COX inhibitors (Table
5). In the alkene series, both the E and Z isomers were
synthesized in order to compare their potencies and
Among the pyrazoles examined for antiinflammatory
activity in vivo, the oxime 23b proved to be the most
potent, selective COX-2 inhibitor with 65% inhibition

2186 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 9
Ranatunge et al.
Ta ble 3. In Vitro Human Whole Blood COX-1 and COX-2
Inhibition by Pyrazolecarbonyl Nitrate and Alcohol Derivatives
Ta ble 5. In Vitro Human Whole Blood COX-1 and COX-2
Inhibition by Alkenyl Pyrazole Nitrate and Alcohol Derivatives
% inhibition HWBa
COX-1 COX-2
100 µM 10 µM 1 µM
% inhibition HWBa
COX-1
COX-2
compd
R1
R2
n
compd
R1
R2
n
100 µM 10 µM 1 µM
26b-I
25b-I
26k -I
25k -I
26b-II cyclohexyl
25b-II
26k -II phenyl
25k -II
27b-II cyclohexyl
15b-II
cyclohexyl
NO2
H
NO2
H
NO2
H
NO2
H
2
2
2
2
2
2
2
2
1
1
1
1
20
45
90
60
60
15
85
25
40
10
50
50
nd
75
95
80
100
90
90
35
90
30
45
15
70
30
95
30
45
5
55
0
0
22b
21b
cyclohexyl
NO2
H
NO2
H
NO2
H
NO2
H
3
3
5
5
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
20
0
25
40
60
0
80
90
75
80
95
20
95
45
100
10
100
85
100
25
100
60
95
70
55
10
55
80
80
35
35
10
70
15
35
0
95
50
55
25
30
30
70
15
10
0
phenyl
22b-i cyclohexyl
21b-i
22k
21k
22l
phenyl
4-methylphenyl
55
0
21l
NO2
H
22m
21m
22n
21n
22o
21o
22p
21p
22q
21q
22r
4-trifluoromethylphenyl NO2
H
45
-20
100
85
40
0
60
10
90
0
0
27h -II cyclohexylmethyl NO2
15h -II
75
45
100
100
35
25
50
75
4-methoxyphenyl
4-fluorophenyl
4-chlorophenyl
4-bromophenyl
4-cyanophenyl
NO2
H
NO2
H
NO2
H
NO2
H
H
Celecoxib
Rofecoxib
a
Percent inhibition of COX-1 (100 µM) or COX-2 (10 and 1 µM)
in human whole blood. Assays were performed in duplicate.
Average % inhibtion of two donors.
Ta ble 6. IC50 Values of Some Pyrazole Compounds in Human
NO2
H
35
0
Blood
21r
Celecoxib
Rofecoxib
nd
75
100
100
50
75
IC50 (µM)
compd
COX-1
COX-2
a
Percent inhibition of COX-1 (100 µM) or COX-2 (10 and 1 µM)
in human whole blood. Assays were performed in duplicate.
Average % inhibition of two donors.
Celecoxib
Rofecoxib
6b
22n
26b-I
14
40
>100
1.5
1000
1.2
0.3
0.4
2.5
0.5
Ta ble 4. In Vitro Human Whole Blood COX-1 and COX-2
Inhibition by Pyrazole Oxime Nitrates
Ta ble 7. In Vivo Antiinflammatory Activity of Select Pyrazole
Derivatives and Standarad COX-2 Inhibitors: Rat Air Pouch
Model
% inhibition
compda
white cell infiltrate
PGE2
Celecoxib
Valdecoxibb
22b
22l
22n
22o
23b
26b-I
60
37
42
nd
43
23
nd
17
97
98
45
20
78
45
65
25
% inhibition HWBa
COX-1
COX-2
compd
R1
R2
n
100 µM 10 µM 1 µM
23b
cyclohexyl
cyclohexyl
cyclohexyl
phenyl
4-cyanophenyl
Celecoxib
Rofecoxib
H
H
CH3
H
H
3
5
3
3
3
10
0
100
35
55
5
23b-i
23b-ii
23k
0
50
0
nd
75
90
85
20
100
100
55
25
10
50
75
a
b
All compounds dosed orally at 45 µmol/kg. Valdecoxib dosed
orally at 15 µmol/kg. nd, not determined.
23r
0.12 mm, respectively) at antiinflammatory doses were
essentially as negligible as the lesions in the control
vehicle group.
a
Percent inhibition of COX-1 (100 µM) or COX-2 (10 and 1 µM)
in human whole blood. Assays were performed in duplicate.
Average % inhibition of two donors.
Aspirin induced 4.86 ( 1.27 mm of gastric lesion,
which is significantly above control. This is consonant
with prior demonstrations that COX-2 selective inhibi-
tors have better gastrointestinal safety than traditional
NSAIDs. A marked difference, however, was noted
between valdecoxib and 23b when they were adminis-
tered with background aspirin treatment. In the setting
of aspirin pretreatment, Valdecoxib potentiated gastric
lesions when compared to either aspirin or valdecoxib
alone. Yet the NO-donor COX-2 inhibitor 23b, even at
of PGE2 formation at an oral dose of 45 µmol/kg in the
air pouch model (Table 7).
Ra t Ga str ic Da m a ge Mod el. The gastric tolerance
of a standard COX-2 inhibitor (valdecoxib) and the lead
NO-donor COX-2 inhibitor (23b), alone and with a
background of aspirin treatment, was studied. Figure
1 shows that the gastric lesions induced by valdecoxib
and 23b (GI lesion scores: 0.75 ( 0.18 mm and 0.38 (

COX-2 Inhibition by Nitric Oxide Donor-Containing Pyrazoles
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 9 2187
Compounds were tested at 100 µM against COX-1 and at 10
µM and 1 µM against COX-2. The % inhibition given in the
tables represents average of two determinations with each
enzyme.
COX In h ibition -Hu m a n Wh ole Blood Assa y. Fresh
heparinized human blood obtained by informed consent, from
nonfasted, male or female donors who had not taken any
asprin or NSAIDs for 14 days was collected in sodium heparin
and distributed in 1 mL aliquots per well of a 24-well tissue
culture plate. The plate was placed on a gently rotating
platform shaker in a 5% CO2 incubator at 37 °C for 15 min.
Test compounds were dissolved and diluted in DMSO, and 1
µL of each dilution of the test compound was added per well
in duplicate wells. To induce COX-2, lipopolysaccharide (LPS)
from E. coli (Sigma Chemical Co., St. Louis, MO) was added
at 10 µg/mL to appropriate wells 15 min after the addition of
the test compounds. For the stimulation of COX-1, the calcium
ionophore, A23187 (Sigma Chemical Co., St. Louis, MO) was
added to a final concentration of 25 µM to separate wells 4.75
h after the addition of the test compounds. At 30 min after
A23187 addition or 5 h after LPS addition, all incubations were
terminated. Thromboxane B2 in the blood samples were
processed39 and assayed in duplicate by EIA (Cayman Chemi-
cal Co., Ann Arbor, MI). The % inhibition given in the tables
represents averages of two determinations on each blood
sample from two donors. The results were not blood-donor
dependent (data not shown).
F igu r e 1. Aspirin-induced rat gastric lesion data for pyrazole-
oxime 23b, COX-2 inhibitors, and NSAIDs (male SD rats).
Dose volume is 1 mL/kg. The ulcerogenicity was scored as
given in the Experimental Section. Values are given as the
arithmetic means ( SEM, Groups D and F were compared to
group C for statistical significance by an ANOVA followed by
Dunnett’s Multiple Comparison Test. * P < 0.01.
An tiin fla m m a tor y Activity-Ra t Air P ou ch Mod el. A
carageenan air pouch model was established essentially as
described.41,42 A pouch was formed in the intrascapular region
of Male Sprague-Dawley rats (∼250 g) by sterile air injection
on days (-6) and (-3). On day 0, test compound or vehicle
was dosed orally (0.5% methylcellulose vehicle) at 45 mg/kg,
in blind fashion, 1 h prior to carrageenan injection (1.0 mL of
a 1.0% solution) into the pouch. After 4 h, the inflammatory
exudate was collected from the pouch for immunoassay of
prostaglandin E2 (PGE2) formation (Cayman). The number of
leukocytes in the exudate was determined by cell counting with
a Beckman Coulter Particle Counter, the lower threshold set
to exclude red blood cells. Twelve animals per treatment group
were used. White cell counts were subjected to statistical
analysis one-way ANOVA (Dunnett test), P < 0.05 defined as
a statistical significance vs vehicle control group.
higher doses relative to valdecoxib in combination with
aspirin did not increase lesion scores compared to
aspirin alone (Figure 1).
Con clu sion
We have disclosed a series of novel pyrazole com-
pounds that are selective, potent COX-2 inhibitors with
promising oral activity as antiinflammatory agents in
vivo. In most cases, hydroxy compounds were less potent
COX-2 selective inhibitors than their corresponding
nitrates. SAR studies indicated that the central pyrazole
ring substituents play an important role in COX-2
potency such that 1-cycloalkyl and 5-aryl pyrazoles (e.g.,
6b ) are potent COX-2 inhibitors. Replacement of the
methyl sulfone moiety in 22b with a sulfonamide group
yielded 33, which was inactive in this series. Other
modifications at the 3-position of the central pyrazole
ring (e.g., 17b, 26b-I, 23b) enhanced COX-2 potency.
Among the pyrazole examined, the oxime 23b proved
to be the most potent COX-2 inhibitor, with appreciable
in vivo antiinflammatory activity and improved gastric
tolerance. Further modifications of selective, orally
active pyrazole-oxime COX-2 inhibitors, such as 23,
could provide a new generation of selective COX-2
inhibitors with improved gastrointestinal (if not overall)
safety.
Ra t Ga str ic In ju r y Mod el. Male Spraque-Dawley rats
(180-200 g) purchased from Charles River. Animals were
housed at 20-22 °C and 65-70% relative humidity on a 12/
12 reverse light/dark cycle, with standard chow and water
available ad libitum.
A minimum of 72 h was allowed for acclimatization of rats
to their new environment prior to experimentation. Eighteen
hours before an experiment, the animals were placed in cages
with raised mesh bottoms and allowed free access to tap water,
but no food. Compounds (including aspirin) were pulverized
with a mortar and pestle and suspended with sufficient
amount of vehicle. All compounds were prepared immediately
before dosing. Aspirin was suspended in 1.0% Methocel,
whereas test compounds were suspended in 0.5% Methocel,
by vortexing in the presence of 2-3 layers of glass beads to
obtain a homogeneous suspension. Compounds were admin-
istered intragastrically using gavage needles at a dose volume
1.0 mL/kg. Four groups of animals were dosed intragastrically
with aspirin (25 mg/kg), and the test compounds were dosed
2 min later.
Three hours postdosing, rats were sacrificed, and their
stomachs were removed, opened along the greater curvature,
and digitally photographed. The images were analyzed using
Image-J software for visible hemorrhagic lesions.
The total length of all lesions for each stomach was summed
and reported as the total lesion score. Images were analyzed
by investigators blinded as to treatment. Values are means (
SEM. The significance of differences between means was
evaluated using a one-way analysis of variance (ANOVA),
followed by Dunnett’s Multiple Comparison Test. P < 0.01 was
considered significant.
Exp er im en ta l Section
COX In h ibition -Recom bin a n t En zym e Assa y. A com-
mercial kit with recombinant human or ovine COX-1 and
human COX-2 enzymes was used to assess inhibition of each
COX isoform. Manufacturer’s (Cayman Chemical Company,
Ann Arbor, MI) protocols were followed with the following
modifications: enzymes were preincubated with heme for 2
min at 25 °C prior to incubation with the test compound at 25
°C for 20 min. Arachidonic acid substrate was then added and
reacted with COX enzyme for 2 min at 37 °C. Prostaglandin
production was quantified by an enzyme-linked immunoassay
(Cayman) using a broadly specific antibody that binds to all
the major prostaglandins and a prostaglandin acetylcholinest-
erase tracer in a microplate format with colorimetric readout.

2188 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 9
Ranatunge et al.
Gen er a l P r oced u r es. All reagents and anhydrous solvents
were generally used as received from the commercial supplier.
Reactions were routinely performed under a nitrogen atmos-
phere in oven-dried glassware. Melting points were determined
with an electrothermal heating block (Metler) and are uncor-
basic with 5% Na2CO3 and extracted with EtOAc which was
then washed with saturated NaHCO3 and water. The organic
extracts were dried over Na2SO4, and the solvent was evapo-
rated under reduced pressure to give a thick oil, which was
purified by chromatography over silica gel eluting with 1:2
EtOAc:Hex to give 3a -I (1 g, 40%) as a colorless oil. Mp 76 °C.
1H NMR δ 7.26-7.35 (m, 4H), 6.76 (s, 1H), 4.59-4.57 (m, 1H),
3.93 (s, 3H), 2.54 (s, 3H), 2.18-2.22 (m, 2H), 1.94-2.02 (m,
4H), 1.46-1.65 (m, 2H); 13C NMR δ 163.2, 144.5, 142.5, 140.3,
129.6, 126.6, 126.4, 108.9, 60.4, 52.0, 33.4, 24.5, 15.5; MS m/z
317 (MH+). Anal. (C17H20N2O2S) C, H, N.
1
rected. H and 13C NMR spectra were recorded at 300 and 75
MHz, respectively. NMR spectra were recorded in CDCl3
unless otherwise specified, and chemical shifts are reported
relative to tetramethylsilane as an internal standard. Low-
resolution mass spectra were obtained using atmospheric
pressure-turbo ion spray ionization. Elemental analyses were
performed by Robertson Microlit Laboratories Inc., NJ . Gravity
and flash column chromatographies were performed using EM
Science silica gel 60 (230-400 mesh). TLC was performed on
250 µM precoated EM Science silica gel 60 F254 aluminum
sheets. Preparative TLC was performed using 20 × 20 cm 1000
µM precoated silica gel plates (Whatman). Spots were visual-
ized under 254 nm light or after staining with phosphomo-
lybdate spray.
1-(1-Cyclop en t yl-3-((n it r ooxy)m et h yl)p yr a zol-5-yl)-4-
(m eth ylsu lfon yl)ben zen e (6a ). N-(Aza cyclop en tylid en e-
m eth yl)(ter t-bu toxy)ca r boxa m id e (6a -a ). Cyclopentanone
(4 g, 47.6 mmol) and tert-butyl carbazate (6.28 g, 47.6 mmol)
in methanol (150 mL) was stirred at room temperature for 2
h. The solvent was evaporated and the resulting solid dried
under vacuo to give 6a -a as a white solid in quantitative yield.
Mp 119-120 °C. 1H NMR δ 7.30-7.47 (bs, 1H), 2.48 (t, J )
7.3 Hz, 2H), 2.21 (t, J ) 6.6 Hz, 2H), 1.67-1.95 (m, 4H), 1.53
(s, 9H); 13C NMR (CDCl3) δ 162.2, 80.8, 33.2, 28.3, 26.9, 24.8,
24.7; MS m/z 199 (MH+). Anal. (C10H18N2O2) C, H, N.
ter t-Bu toxy)-N-(cyclop en tyla m in o)ca r boxa m id e (6a -
b). Sodium cyanoborohydride (2.96 g, 47.1 mmol) was added
portionwise to a suspension of the product of 6a -a (9.4 g, 47.6
mmol) in 50% acetic acid (137 mL) at room temperature. The
resultant clear solution was stirred for 2 h at room tempera-
ture. The reaction mixture was neutralized with 1 N NaOH,
extracted with CH2Cl2, washed with saturated NaHCO3, dried,
filtered, and evaporated to give the title compound as an oil
(8.5 g, 90%). The crude product was used without further
purification. 1H NMR δ 6.25-6.51 (bs, 1H), 4.47-4.20 (bs, 1H),
3.35-3.55 (m, 1H), 1.27-1.80 (m, 8H), 1.53 (s, 9H); 13C NMR
δ 151.6, 75.1, 61.0, 56.2, 25.7, 23.1,18.8; MS m/z 201 (MH+).
(1-Cyclop en t yl-5-(4-m et h ylt h iop h en yl)p yr a zol-3-yl)-
m eth a n -1-ol (4a ). LAH (2.12 mL of 1 M solution in THF, 0.08
g, 2.12 mmol) was added dropwise to a solution of the product
3a -I (0.67 g, 6.78 mmol) in THF (10 mL) at 0 °C. The yellow
solution was stirred at room temperature for 1 h. Solid Na2-
SO4‚10H2O was added portionwise to the reaction mixture at
0 °C, followed by few drops of water and few drops of 0.1 N
NaOH. The solid was filtered and washed with EtOAc. The
residue, obtained after evaporation of the filtrate, was purified
by chromatography over silica gel eluting with 1:1 EtOAc:Hex
1
to give 4a (0.61 g, ∼100%) as a white solid. Mp 98-99 °C. H
NMR δ 7.26-7.33 (m, 4H), 6.20 (s, 1H), 4.70 (s, 2H), 4.54-
4.60 (m, 1H), 2.53 (s, 3H), 2.00-2.20 (m, 2H), 1.79-1.80 (m,
4H), 1.42-1.65 (m, 2H); 13C NMR δ 151.2, 144.1, 139.5, 129.5,
127.8, 126.4, 104.2, 59.5, 59.3, 33.3, 24.8, 15.6; MS m/z 289
(MH+), 271 (M - OH). Anal. (C16H20N2OS•0.6 mol H2O) C, H,
N.
1-(1-Cyclop en tyl-3-(h yd r oxym eth yl)p yr a zol-5-yl)-4-m e-
th ylsu lfon yl)ben zen e (5a ). The product of 4a (0.59 g, 2.04
mmol) was dissolved in MeOH (20 mL). Oxone (2.51 g, 4.09
mmol) in water (9 mL) was added at room temperature. The
reaction mixture was stirred for 1 h, and the resulting solid
was removed by filtration. CH2Cl2 was added to the filtrate,
and it was washed with saturated NaHCO3, water, dried over
Na2SO4, and filtered. The residue after evaporation of the
solvent was recrystallized from CH2Cl2/EtOAc/hexane to give
1
5a (0.5 g, 76%) as white needles. Mp 145-146 °C. H NMR δ
8.04 (dd, J ) 1.74 and 6.7 Hz, 2H), 7.57 (dd, J ) 1.8 and 6.7
Hz, 2H), 6.30 (s, 1H), 4.73 (d, J ) 5.7 Hz, 2H), 4.45-4.60 (m,
1H), 3.11 (s, 3H), 2.03-2.20 (m, 2H), 1.85-2.02 (m, 4H), 1.48-
1.65 (m, 2H); 13C NMR δ 151.6, 142.6, 140.5, 136.7, 130.0,
128.0, 105.2, 59.8, 59.1, 44.6, 33.4, 24.8; MS m/z 321 (MH+),
303 (M - OH), 343 (MNa+). Anal. (C16H20N2O3S) C, H, N.
Cyclop en tylh yd r a zin e Tr iflu or oa ceta te (6a -c). Trifluo-
roacetic acid (25 mL) was added dropwise to a solution of the
product 6a -b (5.8 g, 29 mmol) in CH2Cl2 (25 mL). The reaction
mixture was stirred at room temperature for 1 h. The solvent
was evaporated to give the trifluoroacetate salt of the title
1-(1-Cyclop en t yl-3-((n it r ooxy)m et h yl)p yr a zol-5-yl)-4-
m eth ylsu lfon yl)ben zen e (6a ). The product of 5a (0.2 g, 0.63
mmol) in CHCl3 (2.4 mL) was added to a mixture of fuming
HNO3 (0.13 mL, 0.2 g, 3.13 mmol) and Ac2O (0.47 mL, 0.51 g,
5.0 mmol) at -10 °C and stirred at -10 °C for 20 min. The
reaction mixture was quenched with ice cold water and
extracted with CH2Cl2. The extracts were washed with ice cold
saturated NaHCO3 and water, dried over Na2SO4, and filtered,
and the solvent was evaporated under reduced pressure. The
residue obtained was recrystallized from CH2Cl2/EtOAc/Hex
to give the 6a (0.13 g, 58%) as a white solid. Mp 100-101 °C.
1H NMR δ 8.05 (d, J ) 8.3 Hz, 2H), 7.59 (d, J ) 8.3 Hz, 2H),
6.40 (s, 1H), 5.50 (s, 2H), 4.50-4.65 (m, 1H), 3.12 (s, 3H), 1.82-
2.20 (m, 6H), 1.52-1.70 (m, 2H); 13C NMR δ 143.3, 142.8,
140.9, 136.2, 130.1, 128.0, 107.4, 68.8, 60.2, 44.6, 33.6, 24.9;
MS m/z 366 (MH+), 320 (M - NO2). Anal. (C16H19N3O5S) C,
H, N.
1
compound as a colorless oil in quantitative yield. H NMR δ
3.63-3.72 (m, 1H), 1.92-2.2 (m, 2H), 1.60-1.90 (m, 4H); MS
m/z 101 (MH+).
Meth yl (2Z)-2-Hyd r oxy-4-(4-m eth ylth iop h en yl)-4-oxo-
bu t-2-en oa te (2). Dimethyl oxalate (26 g, 180.7 mmol) was
added to a stirred suspension of sodium methoxide (9.75 g,
180.7 mmol) in dry toluene (200 mL) at 0 °C. The white
suspension was stirred for 15 min at 0 °C. A solution of 4′-
(methylthio)acetophenone (15 g, 90.4 mmol) in dry toluene (150
mL) was then added dropwise over 15 min, giving a yellow
suspension which was stirred for 2 h at room temperature.
The thick yellow suspension was transferred to a 2 L flask
and stirred vigorously with 10% HCl (250 mL) and EtOAc (200
mL) to dissolve all the solids present. The organic layer was
separated and the aqueous layer was extracted with EtOAc
(100 mL). The combined organic extracts were washed with
water (250 mL) and dried over Na2SO4, and the solvent was
evaporated under reduced pressure to give a thick brown oil.
The brown oil was dissolved in CH2Cl2 (25 mL) and hexane
(125 mL) and left in a freezer at -20 °C for 16 h to give 2 (18
For compounds 6b-j see Supporting Information.
4-{1-Cycloh exyl-3-[2-(n it r ooxy)et h yl]p yr a zol-5-yl}-1-
(m eth ylsu lfon yl)ben zen e (12b). Meth yl-1-cycloh exyl-5-
(4-m eth ylth iop h en yl)p yr a zol-3-ca r boxa ld eh yd e (8b). To
a stirred solution of oxalyl chloride (0.66 mL, 0.96 g, 6.1 mmol)
in CH2Cl2 (2.5 mL) at -78 °C under nitrogen was added DMSO
(1.08 mL, 1.19 g, 15.2 mmol) in CH2Cl2 (2 mL) dropwise over
a period of 20 min. To this solution was added 4b (1.84 g, 6.1
mmol) in CH2Cl2 (12 mL) dropwise over a period of 40 min at
-78 °C. The mixture was stirred at -78 °C for 1.5 h.
Triethylamine (4.25 mL, 3.08 g, 30.5 mmol) in CH2Cl2 (2.6 mL)
was then added dropwise over a period of 45 min at -78 °C.
The resultant mixture was stirred at 0°C for 20 min. To this
1
g, 79%) as orange solid. Mp 81 °C. H NMR δ 7.83 (d, J ) 8.6
Hz, 2H), 7.23 (d, J ) 8.6 Hz, 2H), 6.97 (s, 1H), 3.89 (s, 3H),
2.47 (s, 3H); MS m/z 253 (MH+). Anal. (C12H12O4S) C, H, S.
Meth yl 1-Cyclop en tyl-5-(4-m eth ylth iop h en yl)p yr a zol-
3-ca r boxyla te (3a -I). A mixture of 2 (2 g, 7.9 mmol) and 6a -c
(3.36 g, 10.3 mmol) in methanol (40 mL) was heated at 70 °C
for 2 h and cooled to room temperature. The mixture was made

COX-2 Inhibition by Nitric Oxide Donor-Containing Pyrazoles
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 9 2189
mixture was added water (2 mL) dropwise followed by CH2-
Cl2 (50 mL). The organic layer was separated, and the aqueous
layer was extracted with CH2Cl2. The combined organic
extracts were washed with 5% HCl, dried over Na2SO4, and
filtered. The residue after evaporation of the solvent was
recrystallized from CH2Cl2/EtOAc/hexane to give 8b (1.4 g,
min, and a solution of 8b (1.22 g, 4.06 mmol) in THF (10 mL)
was added. The cold bath was removed, and the mixture was
stirred at room temperature for 2 h. Water (50 mL) was added
and the mixture was extracted with EtOAc. The combined
organic extracts were dried over Na2SO4 and filtered. The
solvent was evaporated and the crude product was chromato-
graphed on silica gel eluting with (1:9) EtOAc:hexane to give
13b (1.12 g, 77%) as an oil. 1H NMR δ 7.71 (d, J ) 16 Hz, 1H),
7.32 (d, J ) 6.5 Hz, 2H), 7.23 (d, J ) 6.8 Hz, 2H), 6.43 (s, 1H),
6.38 (d, J ) 16 Hz, 1H), 4.03-4.08 (m, 1H), 3.93 (s, 3H), 2.52
(s, 3H), 1.55-2.00 (m, 7H), 1.22-1.28 (m, 3H); 13C NMR δ
167.4, 146.8, 143.7, 139.8, 137.4, 129.3, 126.7, 126.2, 118.0,
104.6, 58.1, 51.4, 33.2, 25.5, 25.0, 15.3; MS m/z 357 (MH+).
(2E)-3-[1-Cycloh exyl-5-(4-m eth ylth iop h en yl)p yr a zol-3-
yl]p r op -2-en -1-ol (14b). Compound 14b was synthesized in
a manner similar to the synthesis of 4a using 13b (1.12 g, 3.4
mmol) and LAH (3.4 mL of 1M solution in THF, 0.13 g, 3.4
mmol) to give 14b (0.62 g, 60%) as a white solid. Mp 90 °C. 1H
NMR δ 7.25-7.35 (m, 4H), 6.68 (d, J ) 16 Hz, 1H), 6.32-6.39
(m, 1H), 6.31 (s, 1H), 4.30 (d, J ) 5.5 Hz, 2H), 3.98-4.06 (m,
1H), 2.53 (s, 3H), 1.60-1.95 (m, 7H), 1.10-1.30 (m, 3H); 13C
NMR δ 148.8, 143.3, 139.4, 129.6 129.3, 127.5, 123.9, 102.6,
63.6, 57.7, 33.3, 25.6, 25.1, 15.4; MS m/z 329 (MH+).
4-[3-((1E)-3-Hyd r oxyp r op -1-en yl)-1-cycloh exylp yr a zol-
5-yl]-1-(m eth ylsu lfon yl)ben zen e (15b). Compound 15b was
synthesized in a manner similar to the synthesis of 5a using
14b (0.62 g, 1.89 mmol) and Oxone (1.45 g, 2.36 mmol) to give
15b (0.52 g, 76%) as a white solid. Mp 121 °C. 1H NMR δ 7.99
(d, J ) 8.4 Hz, 2H), 7.52 (d, J ) 8.4 Hz, 2H), 6.49 (d, J ) 16
Hz, 1H), 6.35 (s, 1H), 6.29-6.38 (m, 1H), 4.27 (d, J ) 5.5 Hz,
2H), 3.90-3.98 (m, 1H), 3.09 (s, 3H), 1.60-2.10 (m, 7H), 1.10-
1.30 (m, 3H); 13C NMR δ 149.1, 141.7, 140.4, 136.4, 130.3,
129.7, 127.8, 123.2, 103.6, 63.4, 58.2, 44.4, 33.3, 25.5, 24.9; MS
m/z 361 (MH+).
4-[1-Cycloh exyl-3-(3-h yd r oxyp r op yl)p yr a zol-5-yl]-1-
(m eth ylsu lfon yl)ben zen e (16b). Compound 15b (0.52 g, 1.44
mmol) was dissolved in EtOH (20 mL) and degassed with N2.
10% Pd/C (two spatulas) was added and hydrogenated at 20
psi for 3 h. The catalyst was removed by filtration, and the
solvent was removed under reduced pressure. The crude
material was chromatographed on silica gel eluting with (2:1)
EtOAc:Hex to give 16b (0.37 g, 71%) as a white solid. Mp 138
°C.1H NMR δ 8.03 (d, J ) 8.2 Hz, 2H), 7.54 (d, J ) 8.1 Hz,
2H), 6.11 (s, 1H), 3.90-4.00 (m, 1H), 3.75 (t, J ) 5.8 Hz, 2H),
3.30 (bs, 1H), 3.13 (s, 3H), 2.81 (t, J ) 6.9 Hz, 2H), 1.60-2.10
(m, 9H), 1.15-1.30 (m, 3H); 13C NMR δ 151.7, 141.4, 140.2,
136.6, 129.6, 127.8, 105.5, 62.7, 58.0, 44.4, 33.4, 31.5, 25.5, 24.9;
MS m/z 363 (MH+).
1
77%) as a white solid. Mp 63 °C. H NMR δ 9.97 (s, 1H), 7.32
(d, J ) 8.3 Hz, 2H), 7.24 (d, J ) 8.3 Hz, 2H), 6.71 (s, 1H),
4.00-4.18 (m, 1H), 2.52 (s, 3H), 1.50-1.90 (m, 7H), 1.15-1.25
(m, 3H). 13C NMR δ 186.8, 150.4, 144.4, 140.4, 129.3, 126.2,
105.4, 58.7, 33.2, 25.5, 24.5, 15.2. MS m/z 301 (MH+).
4-(1-Cycloh exyl-3-vin ylp yr a zol-5-yl)-1-m eth ylth ioben -
zen e (9b). A solution of BuLi (5.07 mL of 1.6 M solution in
hexane, 8.1 mmol) was added to a stirred solution of methyl-
triphenylphosphonium bromide (2.3 g, 6.5 mmol) in THF (20
mL) at -78 °C under nitrogen. The resulting solution was
stirred for 30 min and then a solution of 8b (1.3 g, 4.3 mmol)
in THF (10 mL) was added. The cold bath was removed, and
the mixture was stirred at room temperature for 2 h. Saturated
NH4Cl (50 mL) was added, and the mixture was extracted with
EtOAc. The combined organic extracts were dried over Na2-
SO4 and filtered. The solvent was evaporated, and the crude
product was chromatographed on silica gel eluting with 5%
1
EtOAc /hexane to afford 9b (0.92 g, 71%) as an oil. H NMR δ
7.21 (d, J ) 8.4 Hz, 2H), 7.16 (d, J ) 8.3 Hz, 2H), 6.68 (dd, J
) 11 and 17.7 Hz, 1H), 6.25 (s, 1H), 5.58 (d, J ) 17.7 Hz, 1H),
5.16 (d, J ) 11 Hz, 1H), 3.85-3.96 (m, 1H), 2.42 (s, 3H), 1.50-
2.00 (m, 7H), 1.05-1.20 (m, 3H); 13C NMR δ 149.7, 143.1,
139.2, 129.5, 129.2, 127.4, 126.2, 114.4, 102.1, 57.6, 33.2, 25.5,
25.0, 15.3; MS m/z 299 (MH+).
2-(1-Cycloh exyl-5-(4-m et h ylt h iop h en yl)p yr a zol-3-yl)-
1-eth a n -1-ol (10b). A solution of BH3‚THF complex (1 M
solution in THF, 6 mL, 6 mmol) was added dropwise to a
stirred solution of 9b (0.9 g, 3 mmol) in THF at 0 °C and stirred
for 45 min at 0 °C. 10% NaOH (6 mL) was added and followed
by a 30% H2O2 solution (6 mL) dropwise. The product was
extracted with EtOAc, dried over Na2SO4, filtered, and con-
centrated under reduced pressure. The crude material was
chromatographed on silica gel eluting with (1:1) EtOAc/hexane
1
to give 10b (0.18 g, 19%) as an oil. H NMR δ 7.23 (d, J ) 8.3
Hz, 2H), 7.17 (d, J ) 8.3 Hz, 2H), 5.95 (s, 1H), 3.82-3.96 (m,
1H), 3.84 (t, J ) 5.7 Hz, 2H), 3.30 (bs, 1H), 2.80 (t, J ) 5.7 Hz,
2H), 2.44 (s, 3H), 1.05-1.95 (m, 10H); 13C NMR δ 149.5, 142.8,
139.2, 129.2, 127.5, 126.2, 104.7, 61.9, 57.5, 33.3, 30.9, 25.6,
25.1, 15.4; MS m/z 317 (MH+).
2-(1-Cycloh exyl-3-(2-h yd r oxyeth yl)p yr a zol-5-yl)-1-(m e-
th ylsu lfon yl)ben zen e (11b). Compound 11b was synthesized
in a manner similar to the synthesis of 5a using 10b (0.17 g,
0.53 mmol) and Oxone (0.66 g, 1.07 mmol) to give 11b (0.18 g,
4-{1-Cycloh exyl-3-[3-(n itr ooxy)p r op yl]p yr a zol-5-yl}-1-
(m eth ylsu lfon yl)ben zen e (17b). Compound 17b was syn-
thesized in a manner similar to the synthesis of 6a using 16b
(0.14 g, 0.38 mmol), fuming HNO3 (81 µL, 0.12 g, 1.93 mmol),
and Ac2O (0.29 mL, 0.31 g, 3.09 mmol) to give 17b (0.11 g,
1
96%) as a white solid. Mp 108 °C. H NMR δ 7.95 (d, J ) 8.1
Hz, 2H), 7.48 (d, J ) 8.1 Hz, 2H), 6.07 (s, 1H), 3.81-3.94 (m,
1H), 3.83 (t, J ) 5.9 Hz, 2H), 3.33 (bs, 1H), 3.05 (s, 3H), 2.81
(t, J ) 5.9 Hz, 2H), 1.50-2.05 (m, 7H), 1.05-1.25 (m, 3H); 13
C
1
70%) as a yellow solid. Mp 77 °C. H NMR δ 8.04 (d, J ) 8.1
NMR 149.8, 141.2, 140.1, 136.4, 129.5, 127.7, 105.6, 61.7, 57.9,
44.3, 33.2, 30.9, 25.4, 24.9; MS m/z 349 (MH+). Anal.
(C18H24N2O3S‚0.25H2O) C, H, N.
Hz, 2H), 7.55 (d, J ) 8.1 Hz, 2H), 6.19 (s, 1H), 4.53 (t, J ) 6.4
Hz, 2H), 3.95-4.07 (m, 1H), 3.11 (s, 3H), 2.85 (t, J ) 7.45 Hz,
2H), 1.69-2.20 (m, 9H), 1.10-1.30 (m, 3H); 13C NMR δ 150.1,
142.5, 140.9, 135.2, 129.7, 127.9, 105.7, 72.4, 58.8, 44.3, 32.8,
26.4, 25.4, 24.6, 23.7; MS m/z 408 (MH+).
4-{1-Cycloh exyl-3-[2-(n it r ooxy)et h yl]p yr a zol-5-yl}-1-
(m eth ylsu lfon yl)ben zen e (12b). Compound 12b was syn-
thesized in a manner similar to the synthesis of 6a using 11b
(0.16 g, 0.45 mmol), fuming HNO3 (94 µL, 0.14 g, 2.24 mmol),
and Ac2O (0.34 mL, 0.37 g, 3.58 mmol) to give 12b (0.12 g,
For compound 17h , see Supporting Information.
1-(1-(Cycloh exyl-5-(4-(m eth ylsu lfon yl)p h en yl)p yr a zol-
3-yl)-4-(n itr ooxy)bu tan -1-on e (22b). Meth yl(2Z)-2-h ydr oxy-
4-(4-(m eth ylsu lfon yl)p h en yl)-4-oxobu t-2-en oa te (2A). Ox-
one (4.39 g, 7.1 mmol) in water (14 mL) was added dropwise
to a solution of 2 (1.5 g, 6.0 mmol) in a mixture of MeOH (30
mL) and CH2Cl2 (2 mL) at 0 °C. The resultant suspension was
gradually warmed to room temperature over a period of 1 h.
The solid was filtered, and the filtrate was diluted with CH2-
Cl2, washed with saturated NaHCO3 and water, dried (Na2-
SO4), and filtered. The solvent was evaporated to give 2A (0.8
g, 47%). MS m/z 285 (MH+), 302 (MNH4+).
1
66%) as a yellow solid. Mp 117 °C. H NMR δ 7.98 (d, J ) 8.3
Hz, 2H), 7.50 (d, J ) 8.3 Hz, 2H), 6.15 (s, 1H), 4.70 (t, J ) 6.7
Hz, 2H), 3.85-4.05 (m, 1H), 3.07 (s, 3H), 3.04-3.08 (m, 2H),
1.60-2.00 (m, 7H), 1.10-1.30 (m, 3H); 13C NMR δ 146.5, 141.9,
140.6, 135.9, 129.7, 127.8, 106.0, 71.9, 58.4, 44.3, 33.1, 26.0,
25.5, 24.8; MS m/z 394 (MH+).
4-{1-Cycloh exyl-3-[3-(n itr ooxy)p r op yl]p yr a zol-5-yl}-1-
(m eth ylsu lfon yl)ben zen e (17b). Meth yl (2E)-3-[1-Cyclo-
h e x y l-5-(4-m e t h y lt h i o p h e n y l)p y r a z o l-3-y l]p r o p -2-
en oa te (13b). A solution of BuLi (3.2 mL of 1.6 mol solution
in hexane, 5.2 mmol) was added to a stirred solution of
trimethylphosphonoacetate (0.92 g, 5.08 mmol) in THF (10 mL)
at -78 °C under N2. The resulting solution was stirred for 30
Meth yl-1-cycloh exyl-5-(4-m eth ylsu lfon ylp h en yl)p yr a -
zole-3-ca r boxyla te (7b). Compound 7b was synthesized in
a manner similar to the synthesis of 3a -I using 2A (7.4 g, 26

2190 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 9
Ranatunge et al.
mmol) and cyclohexyl hydrazine hydrochloride (4.3 g, 29 mmol)
7.56 (d, J ) 8.2 Hz, 2H), 6.81 (s, 1H), 4.59 (t, J ) 6.4 Hz, 2H),
4.04-4.09 (m, 1H), 3.21 (t, J ) 7.1 Hz, 2H), 3.13 (s, 3H), 2.15-
2.24 (m, 2H), 1.67-2.13 (m, 7H), 1.12-1.42 (m, 3H); 13C NMR
δ 194.7, 149.9, 142.6, 141.1, 135.7, 130.0, 128.2, 107.2, 72.8,
59.2, 44.6, 34.5, 33.4, 25.5, 25.1, 21.5; MS m/z 436 (MH+). Anal.
(C20H25N3O6S) C, H, N.
in MeOH (100 mL) to give 7b (8.3 g, 88%) as a tan solid. Mp
1
108 °C. H NMR δ 8.09 (d, J ) 8.4 Hz, 2H), 7.59 (d, J ) 8.4
Hz, 2H), 6.88 (s, 1H), 4.06-4.10 (m, 1H), 3.97 (s, 3H), 3.16 (s,
3H), 1.26-2.19 (m, 10H). MS m/z 375 (MH+). Anal. (C19H22N2-
O4S) C, H, N.
For compounds 22b-i, 22k -r , see Supporting Information.
(1-Cycloh exyl-5-(4-m et h ylsu lfon yl)p h en yl)p yr a zol-3-
yl)-N-m eth oxy-N-m eth ylca r boxa m id e (18b-A). Trimethyl-
aluminum (5.52 mL of 2 M solution in hexane, 0.80 g, 11.1
mmol,) was added dropwise to a suspension of dimethylhy-
droxylamine hydrochloride (1.11 g, 11.4 mmol) in CH2Cl2 (10
mL) at 0 °C. The solution was stirred at 0 °C for 45 min and
then at room temperature for 40 min. To this solution, 7b (2.06
g, 5.7 mmol) in CH2Cl2 (4 mL) was added dropwise. Stirring
was continued for 2 h at room temperature. The reaction
mixture was cooled to 0 °C, and 10% HCl was carefully added
dropwise. The aqueous phase was extracted with EtOAc,
washed with water, brine, dried over Na2SO4, and filtered. The
residue after evaporation of the solvent was dissolved in CH2-
Cl2 and filtered through a silica gel pad that was washed with
EtOAc. The combined filtrate and washings were evaporated
to give 18b-A (1.48 g, 67%) as a white solid. Mp 53 °C. 1H
NMR δ 8.28 (d, J ) 8.3 Hz, 2H), 7.58 (d, J ) 8.3 Hz, 2H), 6.81
(s, 1H), 4.00-4.20 (m, 1H), 3.85 (s, 3H), 3.48 (bs, 3H), 3.13 (s,
3H), 1.78-2.20 (m, 7H), 1.13-1.37 (m, 3H); 13C NMR δ 144.6,
141.3, 140.9, 136.0, 130.0, 128.1, 109.5, 61.7, 59.0, 44.6, 33.5,
25.6, 25.1, 14.7, 14.2; MS m/z 392 (MH+). Anal. (C19H25N3O4S)
C, H, N.
1-(1-Cycloh exyl-3-(1-(h ydr oxyim in o)-4-(n itr ooxy)bu tyl)-
pyr azol-5-yl)-4-(m eth ylsu lfon yl)ben zen e (23b). NaOH (49.8
mg, 1.24 mmol, 83 µL of 15 N solution) was added dropwise
to a suspension of 22b (0.22 g, 0.50 mmol) and hydroxylamine
hydrochloride (87.9 mg, 1.26 mmol) in EtOH (4 mL) and CH2-
Cl2 (1 mL), and the reaction mixture was stirred at room
temperature for 4 h. The residue after evaporation of the
solvent was extracted into EtOAc, washed with water, dried
Na2SO4, and filtered. The filtrate was evaporated in vacuo to
give the crude product which was purified by preparative layer
chromatography (elution with 1:1 EtOAc:hexane) to give 23b
as a mixture of isomers (0.11 g, 89% based on recovered
starting material (0.1 g)) as a white solid. Mp 121-123 °C. 1H
NMR δ 8.07 (d, J ) 14.2 Hz, 0.4H), 8.06 (d, J ) 6.7 Hz, 2H),
7.58 (d, J ) 14.1 Hz, 0.4H), 7.57 (d, J ) 6.6 Hz, 2H), 6.84 (s,
0.2H), 6.57 (s, 1H), 4.58 (t, J ) 6.4 Hz, 0.4H), 4.54 (t, J ) 6.6
Hz, 2H), 3.95-4.08 (m, 1H), 3.14 (s, 0.6H), 3.13 (s, 3H), 3.03
(t, J ) 7.2 Hz, 2H), 2.83 (t, J ) 7.3 Hz, 0.4H), 2.12 (p, J ) 6.8
Hz, 2H), 1.80-2.08 (m, 8H), 1.60-1.75 (m, 1H); MS m/z 451
(MH+). Anal. (C20H26N4O6S) C, H, N.
For compounds 23b-i, 23b-ii, 23k , and 23r , see Supporting
1-(1-Cycloh exyl-5-(4-(m eth ylsu lfon yl)p h en yl)p yr a zol-
3-yl)-4-(1,1,2,2-tetr am eth yl-1-silapr opoxy)bu tan -1-on e (19-
A). To a solution of 18b-A (1.0 g, 2.56 mmol) in THF (20 mL)
was added dropwise the Grignard reagent prepared from
3-bromo-1-(1,1,2,2-tetramethyl-1-silapropoxy)propane (5 g, 19.8
mmol) and magnesium turnings (1.02 g, 42.5 mmol) in THF
(50 mL) at 0 °C under nitrogen. The reaction mixture was
gradually warmed to room temperature. After all the starting
material had been consumed, saturated NH4Cl was added
dropwise at 0 °C. The reaction mixture was diluted with
EtOAc, and the layers were separated. The aqueous layer was
extracted with EtOAc, and the combined organic layers were
washed with water, dried (Na2SO4), and filtered. The residue
after evaporation of the solvent was chromatographed on silica
gel, eluting with 1:10 to 2:10 to 1:2 to 1:1 to 2:1 EtOAc:Hex to
give 19b-A (1.27 g, 98%) as a white solid. Mp 131-133 °C. 1H
NMR δ 8.08 (d, J ) 8.4 Hz, 2H), 7.58 (d, J ) 8.4 Hz, 2H), 6.82
(s, 1H), 3.95-4.25 (m, 1H), 3.74 (t, J ) 6.3 Hz, 2H), 3.16 (s,
3H), 3.13 (t, J ) 7.4 Hz, 2H), 1.80-2.20 (m, 9H), 1.22-1.40
(m, 3H), 0.91 (s, 9H), 0.08 (s, 6H); 13C NMR δ 196.5, 150.3,
142.4, 141.0, 135.9, 130.0, 128.1, 107.1, 62.7, 59.0, 44.6, 35.3,
33.4, 27.6, 26.1, 25.5, 25.1, 18.5, -5.2; MS m/z 505 (MH+). Anal.
(C26H40N2O4SSi) C, H, N.
1-(1-Cycloh exyl-5-(4-(m eth ylsu lfon yl)p h en yl)p yr a zol-
3-yl)-4-h ydoxybu tan -1-on e (21b). Tetrabutylammonium fluo-
ride (2.57 mL of 1 M solution of THF, 0.67 g, 2.57 mmol) was
added dropwise to a solution of 19b-A (1.04 g, 2.06 mmol) in
THF (24 mL) at 0 °C. The resultant solution was stirred at 0
°C for 2 h and then at room temperature for 3 h. The residue
after evaporation of the solvent was chromatographed on silica
gel, eluted with 1:1 to 2:1 EtOAc:Hex to give an oil which was
recrystallized from CH2Cl2/EtOAc/Hex to give 21b (0.64 g,
79%). Mp 112-114 °C. 1H NMR δ 8.07 (d, J ) 8.3 Hz, 2H),
7.57 (dd, J ) 1.7 and 6.7 Hz, 2H), 6.83 (s, 1H), 4.00-4.20 (m,
1H), 3.65-3.80 (m, 2H), 3.19 (t, J ) 6.9 Hz, 2H), 3.14 (s, 3H),
2.32 (t, J ) 5.8 Hz, 1H), 2.03 (p, J ) 6.8 Hz, 2H), 1.68-1.97
(m, 6H), 1.18-1.40 (m, 4H). 13C NMR δ196.9, 150.4, 142.7,
141.1, 135.7, 130.0, 128.2, 107.3, 62.3, 59.2, 44.6, 35.4, 33.5,
27.8, 25.5, 25.1; MS m/z 391 (MH+), 373 (M - OH). Anal.
(C20H26N2O4S) C, H, N.
Information.
1-(3-((1Z)-4-(Nitr ooxy)bu t-1-en yl)-1-cycloh exylp yr a zol-
5-yl)-4- (m eth ylsu lfon yl) ben zen e (26b-I). 1-((3Z)-4-(1-
Cycloh exyl-5-(4-m et h ylt h iop h en yl)p yr a zol-3-yl)b u t -3-
en yloxy)-1,1,2,2- tetr am eth yl-1-silapr opan e (24b-I). n-Butyl-
lithium (2.5 M solution in hexane, 2.25 mL, 0.36 g, 5.6 mmol)
was added dropwise to solution of (3-((1,1-dimethylethyl)-
dimethylsilyl)oxy)propyl)triphenylphosphonium bromide (2.45
g, 4.76 mmol) in THF (13 mL) at -78 °C. The resultant
solution was stirred at -78 °C for 1 h. To this solution was
added 8b (1.3 g, 4.3 mmol) in THF (13 mL) dropwise. The
reaction mixture was stirred at -78 °C for 1 h. The reaction
mixture was gradually allowed to warm to room temperature
and stirred for 24 h. Water was added, and the reaction
mixture was extracted with EtOAc. The organic layer was then
washed with water, dried over Na2SO4, and filtered. The
residue obtained after evaporation of the solvent was purified
by chromatography on silica gel eluting with (0.5:10) EtOAc:
Hex to give the pure Z-isomer, 24b-I (1.2 g, 61%) as a colorless
oil and minor E-isomer, 24b-II (0.1 g, 5%). Z-isomer: 1H NMR
δ 7.33 (d, J ) 8.4 Hz, 2H), 7.28 (d, J ) 8.5 Hz, 2H), 6.47 (d, J
) 11.7 Hz, 1H), 6.28 (s, 1H), 5.65-5.77 (m, 1H), 3.98-4.12
(m, 1H), 3.76 (t, J ) 6.9 Hz, 2H), 2.72 (q, J ) 6.1 Hz, 2H),
2.54 (s, 3H), 1.60-2.18 (m, 7H), 1.15-1.40 (m, 3H), 0.90 (s,
9H), 0.07 (s, 6H); 13C NMR δ 148.4, 142.8, 139.3, 129.5, 128.7,
127.8, 126.4, 122.7, 105.9, 62.9, 57.8, 33.5, 33.1, 26.1, 25.8, 25.3,
18.5, 15.6, -5.0; MS m/z 457 (MH+).
1-(3-((1Z)-4-(Hyd r oxy)bu t-1-en yl)-1-cycloh exylp yr a zol-
5-yl-4-m eth ylsu lfon yl)ben zen e (25b-I). The product of 24b-I
(1.17 g, 2.6 mmol) was dissolved in MeOH (51 mL). Oxone (4.73
g, 7.7 mmol) in water (11 mL) was added at room temperature.
The reaction mixture was stirred for 1 h and then filtered to
remove the solid. CH2Cl2 was added to the filtrate which was
washed with saturated NaHCO3, water, dried over Na2SO4,
and filtered. The residue after evaporation of the solvent was
recrystallized from CH2Cl2/EtOAc/hexane to give 25b-I (0.88
1
g, 92%) as a white solid. Mp 170-172 °C. H NMR δ 8.05 (d,
J ) 8.3 Hz, 2H), 7.56 (d, J ) 8.3 Hz, 2H), 6.50 (d, J ) 11.5 Hz,
1H), 6.27 (s, 1H), 5.80-5.94 (m, 1H), 3.90-4.10 (m, 1H), 3.87
(q, J ) 5.7 Hz, 2H), 3.79 (t, J ) 4.7 Hz, 1H), 3.13 (s, 3H), 2.75
(q, J ) 5.9 Hz, 2H), 1.62-2.18 (m, 7H), 1.18-1.40 (m, 3H);
13C NMR δ 148.1, 141.5, 140.7, 136.5, 130.4, 129.9, 128.1,
123.1, 107.1, 62.6, 58.5, 44.6, 33.6, 32.4, 25.7, 25.1. MS m/z
375 (MH+). Anal. (C20H26N2O3S) C, H, N, S.
1-(1-(Cycloh exyl-5-(4-(m eth ylsu lfon yl)p h en yl)p yr a zol-
3-yl)-4-(n itr ooxy)bu ta n -1-on e (22b). Compound 22b was
synthesized in a manner similar to the synthesis of 6a using
21b (0.5 g, 1.28 mmol), fuming HNO3 (0.27 mL, 0.40 g, 6.4
mmol), and Ac2O (0.96 mL, 1.04 g, 10.3 mmol) to give 22b (0.41
1-(3-((1Z)-4-(Nitr ooxy)bu t-1-en yl)-1-cycloh exylp yr a zol-
5-yl)-4-(m eth ylsu lfon yl)ben zen e (26b-I). Compound 26b-I
1
g, 74%). Mp 122-124 °C. H NMR δ 8.07 (d, J ) 8.2 Hz, 2H),

COX-2 Inhibition by Nitric Oxide Donor-Containing Pyrazoles
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 9 2191
was synthesized in a manner similar to the synthesis of 6a
using 25b-I (0.2 g, 0.53 mmol) in CHCl3 (2.2 mL), fuming
HNO3 (0.11 mL, 0.17 g, 2.67 mmol), and Ac2O (0.40 mL, 0.44
g, 4.27 mmol) to give 26b-I (0.16 g, 71%) as a white solid. Mp
137-138 °C. 1H NMR δ 8.05 (dd, J ) 1.5 and 8.4 Hz, 2H),
7.57 (dd, J ) 1.7 and 6.7 Hz, 2H), 6.48 (d, J ) 10.2 Hz, 1H),
6.27 (s, 1H), 5.62-5.74 (m, 1H), 4.64 (t, J ) 6.9 Hz, 2H), 3.93-
4.10 (m, 1H), 3.13 (s, 3H), 3.00-3.05 (m, 2H), 1.78-2.14 (m,
6H), 1.62-1.77 (m, 1H), 1.19-1.38 (m, 3H); 13C NMR δ 148.0,
141.3, 140.6, 136.6, 129.9, 128.1, 125.7, 124.1, 107.2, 72.7, 58.5,
44.6, 33.5, 27.3, 25.7, 25.2; MS m/z 420 (MH+). Anal.
(C20H25N3O5S•1/4 mol H2O) C, H, N.
1-(3-((1E)-4-(Nitr ooxy)bu t-1-en yl)-1-cycloh exylp yr a zol-
5-yl)-4-(m eth ylsu lfon yl)ben zen e (26b-II). 1-((3E)-4-(1-Cy-
cloh exyl-5-(4-m et h ylt h iop h en yl)p yr a zol-3-yl)b u t -3-en -
yloxy)-1,1,2,2-tetr a m eth yl-1-sila p r op a n e (24b-II). Com-
pound 24b-II was synthesized in a manner similar to the 24b-I
to give Z-isomer, 24b-I (1.2 g, 61%) as a colorless oil and
E-isomer, 24b-II (0.1 g, 5%). E-isomer, 24b-II: 1H NMR δ
7.22-7.35 (m, 4H), 6.51 (d, J ) 16.1 Hz, 1H), 6.26 (s, 1H),
6.12-6.25 (m, 1H), 3.92-4.08 (m, 1H), 3.72 (t, J ) 7.10 Hz,
2H), 2.53 (s, 3H), 2.37-2.48 (m, 2H), 1.56-2.10 (m, 7H), 1.16-
1.30 (m, 3H), 0.91 (s, 9H), 0.07 (s, 6H); 13C NMR δ 149.8, 143.3,
139.3, 129.5, 128.1, 127.9, 126.5, 124.4, 102.1, 63.3, 57.8, 36.7,
33.5, 26.1, 25.8, 25.3, 18.5, 15.6, -5.0. MS m/z 457 (MH+).
rated, dried over Na2SO4, and the solvent was evaporated in
vacuo to give the crude product. The crude product was
chromatographed on silica gel eluting with 10% MeOH/CH2-
Cl2 to give 28 (1.5 g, 45%) as an oil. 1H NMR δ 7.77 (d, J ) 8.3
Hz, 2H), 7.51 (d, J ) 8.3 Hz, 2H), 6.78 (s, 1H), 3.98-4.20 (m,
1H), 3.72 (t, J ) 6.4 Hz, 2H), 3.12 (t, J ) 7.3 Hz, 2H), 2.81 (s,
3H), 1.78-2.10 (m, 10H), 1.14-1.33 (m, 2H), 0.90 (s, 9H), 0.06
(s, 6H); 13C NMR δ 196.6, 150.2, 146.7, 143.0, 133.3, 130.0,
124.3, 106.8, 62.7, 58.8, 44.0, 35.3, 33.4, 27.6, 26.1, 25.6, 25.1,
18.4, -5.3; MS m/z 488 (MH+). Anal. (C26H39N2O3SSi) C, H,
N.
(4-{1-Cycloh exyl-3-[4-(1,1,2,2-t et r a m et h yl-1-sila p r o-
p oxy)bu ta n oyl]p yr a zol-5-yl}p h en ylth io)m eth yl Aceta te
(29). Compound 28 (1.5 g, 3.1 mmol) was dissolved in acetic
anhydride (12 mL). Powdered sodium acetate (1.1 g, 13.4
mmol) was added, and the solution was refluxed for 8 h. The
solvent was evaporated in vacuo. The residue was taken up
in (1:0.5) EtOAc:CH2Cl2, washed with sat. NH4Cl and brine,
and dried over Na2SO4. The solvent was removed under vacuo
to give 29 (0.9 g, 56%) as an oil. 1H NMR δ 7.54 (d, J ) 8.3
Hz, 2H), 7.31 (d, J ) 8.3 Hz, 2H), 6.73 (s, 1H), 5.49 (s, 2H),
4.00-4.18 (m, 1H), 3.73 (t, J ) 6.4 Hz, 2H), 3.11 (t, J ) 7.3
Hz, 2H), 2.15 (s, 3H), 1.83-2.00 (m, 10H), 1.12-1.32 (m, 2H),
0.91 (s, 9H), 0.06 (s, 6H); 13C NMR δ 196.8, 170.3, 150.1, 143.5,
136.3, 129.8, 129.2, 106.5, 67.4, 62.8, 58.6, 35.3, 33.4, 27.7, 26.1,
25.6, 25.2, 21.2, 18.4, -5.2; MS m/z 531 (MH+). Anal.
(C28H42N2O4SSi) C, H, N.
[(4-{1-Cycloh exyl-3-[4-(1,1,2,2-t et r a m et h yl-1-sila p r o-
poxy)bu tan oyl]pyr azol-5-yl}ph en yl) su lfon yl]m eth yl Ace-
ta te (30). Compound 29 (0.9 g, 1.7 mmol) and MMPP (0.92 g,
1.86 mmol) were mixed in CH2Cl2 (16 mL) and MeOH (5 mL)
and was stirred at room temperature for 16 h. The reaction
mixture was neutralized with saturated NaHCO3, and the
solvent was evaporated to half of its volume. The residue was
extracted into CH2Cl2, washed with saturated NaHCO3 and
water, dried over Na2SO4, filtered, and evaporated to give 30
(0.74 g, 78%) as an oil. 1H NMR δ 8.05 (d, J ) 8.3 Hz, 2H),
7.58 (d, J ) 8.3 Hz, 2H), 6.83 (s, 1H), 5.21 (s, 2H), 3.98-4.12
(m, 1H), 3.73 (t, J ) 6.3 Hz, 2H), 3.12 (t, J ) 7.4 Hz, 2H), 2.13
(s, 3H), 1.82-2.10 (m, 9H), 1.20-1.35 (m, 1H), 1.20-1.35 (m,
2H), 0.89 (s, 9H), 0.06 (s, 6H); 13C NMR δ 196.4, 168.3, 150.4,
142.2, 137.3, 136.7, 130.0, 129.6, 107.3, 62.7, 59.1, 35.3, 34.8,
33.4, 31.7, 27.6, 26.1, 25.5, 25.1, 22.8, 20.4, 18.4, 14.2, -5.1;
MS m/z 563 (MH+). Anal. (C28H42N2O6SSi) C, H, N.
4-{1-Cycloh exyl-3-[4-(1,1,2,2-tetr am eth yl-1-silapr opoxy)-
bu ta n oyl]p yr a zol-5-yl}ben zen esu lfon a m id e (31). Sodium
acetate (0.77 g, 9.4 mmol) was added to a solution of 30 (0.66
g, 1.17 mmol) in methanol (14 mL). The resultant mixture was
stirred at room temperature for 15 min. K2CO3 (0.46 g, 3.3
mmol) was added, and the stirring was continued for 1.5 h.
To this solution was added hydroxyaminosulfonic acid (0.53
g, 4.69 mmol). The mixture was stirred at room temperature
for 2 h and diluted with EtOAc, and saturated NaHCO3 was
added. The solvent was evaporated to a small volume, and
more EtOAc was added. The layers were separated, and the
organic layer was washed with saturated NaHCO3 and brine,
dried over Na2SO4, and filtered. The residue after evaporation
of the solvent was chromatographed on silica gel eluting with
1:2 to 1:1 EtOAc:hexane to give 31 (0.38 g, 64%) as a white
solid. Mp 151-153 °C. 1H NMR δ 8.04 (d, J ) 8.4 Hz, 2H),
7.50 (d, J ) 8.4 Hz, 2H), 6.78 (s, 1H), 4.96 (s, 2H), 3.92-4.10
(m, 1H), 3.72 (t, J ) 6.3 Hz, 2H), 3.12 (t, J ) 7.3 Hz, 2H),
1.75-2.10 (m, 8H), 1.48-1.60 (m, 2H), 1.20-1.38 (m, 2H), 0.90
(s, 9H), 0.06 (s, 6H); MS m/z 506 (MH+).
1-(3-((1E)-4-(Hyd r oxy)bu t-1-en yl)-1-cycloh exylp yr a zol-
5-yl)-4-m eth ylsu lfon yl)ben zen e (25b-II). Compound 25b-
II was synthesized in a manner similar to the synthesis of
25b-I using 24b-II (0.23 g, 0.67 mmol) in MeOH (14 mL) and
Oxone (0.83 g, 13.4 mmol) in water (3 mL) to give 25b-II (0.16
1
g, 64%) as a white solid. Mp 129-130 °C. H NMR δ 8.04 (d,
J ) 8.2 Hz, 2H), 7.55 (d, J ) 8.2 Hz, 2H), 6.07 (d, J ) 16.0 Hz,
1H), 6.37 (s, 1H), 6.16-6.30 (m, 1H), 3.89-4.08 (m, 1H), 3.77
(q, J ) 6.0 Hz, 2H), 3.13 (s, 3H), 2.49 (q, J ) 6.5 Hz, 2H),
1.42-2.12 (m, 7H), 1.10-1.37 (m, 3H). 13C NMR δ 149.9, 141.8,
140.6, 136.8, 129.9, 128.2, 128.1, 125.1, 103.4, 62.2, 58.4, 44.7,
36.5, 33.5, 25.8, 25.2. MS m/z 375 (MH+). Anal. (C20H26N2O3S‚
0.25H2O) C, H, N.
1-(3-((1E)-4-(Nitr ooxy)bu t-1-en yl)-1-cycloh exylp yr a zol-
5-yl)-4-(m eth ylsu lfon yl)ben zen e (26b-II). Compound 26b-
II was synthesized in a manner similar to the synthesis of 6a
using 25b-II (0.1 g, 0.27 mmol) in CHCl3 (1.1 mL), fuming
HNO3 (56 µL, 84 mg, 1.34 mmol) and Ac2O (0.20 mL, 0.22 g,
2.14 mmol) to give 26b-II as a white foam. 1H NMR δ 8.05
(dd, J ) 1.5 and 8.4 Hz, 2H), 7.57 (dd, J ) 1.7 and 6.7 Hz,
2H), 6.57 (d, J ) 16.0 Hz, 1H), 6.37 (s, 1H), 6.09-6.23 (m,
1H), 4.57 (t, J ) 6.7 Hz, 2H), 3.90-4.12 (m, 1H), 3.13 (s, 3H),
2.55-2.68 (m, 2H), 1.60-2.12 (m, 7H), 1.12-1.35 (m, 3H). 13
C
NMR δ 149.3, 141.9, 140.6, 136.6, 129.9, 128.0, 125.9, 125.1,
103.5, 72.3, 58.4, 44.6, 33.5, 31.7, 30.5, 25.7, 25.1. MS m/z 420
(MH+). Anal. (C20H25N3O5S) C, H, N.
For compounds 26k -I, 26k -II, and 27h -II, see Supporting
Information.
4-{1-Cycloh exyl-3-[4-(n itr ooxy)bu ta n oyl]p yr a zol-5-yl}-
ben zen esu lfon am ide (33). 1-[1-Cycloh exyl-5-(4-m eth ylth io-
ph en yl)pyr azol-3-yl]-4-(1,1,2,2-tetr am eth yl-1-silapr opoxy)-
bu ta n -1-on e (19b). Compound 19b was synthesized in a
manner similar to the synthesis of 19b-A using 18b (3.9 g,
11.0 mmol) in THF (30 mL), the Grignard reagent prepared
from 3-bromo-1-(1,1,2,2-tetramethyl-1-silapropoxy)propane (25
g, 98.8 mmol) and magnesium turnings (5.0 g, 20.8 mol) in
1
THF (180 mL) to give 19b (3.79 g, 48%) as a colorless oil. H
NMR δ 7.20-7.38 (m, 4H), 6.71 (s, 1H), 4.02-4.20 (m, 1H),
3.72 (t, J ) 6.4 Hz, 2H), 3.10 (t, J ) 7.3 Hz, 2H), 2.54 (s, 3H),
1.72-2.05 (m, 10H), 1.19-1.32 (m, 2H), 0.91 (s, 9H), 0.06 (s,
6H); MS m/z 473 (MH+).
1-{1-Cycloh exyl-5-[4-(m eth ylsu lfin yl)p h en yl]p yr a zol-
3-yl}-4-(1,1,2,2-tetr am eth yl-1-silapr opoxy)bu tan -1-on e (28).
Compound 19b (3.23 g, 6.84 mmol) was dissolved in CH2Cl2
(48 mL) and MeOH (15 mL). Magnesium monoperoxyphatha-
late hexahydrate (MMPP) (1.83 g, 3.69 mmol) was added in
five equal portions at 1 min intervals. The resulting hetero-
geneous solution was stirred at room temperarture for 1 h.
Saturated NaHCO3 was added. The organic layer was sepa-
4-[1-Cycloh exyl-3-(4-h ydr oxybu tan oyl)pyr azol-5-yl]ben -
zen esu lfon a m id e (32). Tetrabutylammonium fluoride (0.75
mL of 1 M solution in THF, 0.20 g, 0.75 mmol) was added
dropwise to a solution of 31 (0.38 g, 0.75 mmol) in THF (9 mL).
The reaction mixture was stirred at room temperature for 16
h. The residue after evaporation of the solvent was chromato-
graphed on silica gel eluting with 1:1 EtOAc:CH2Cl2 to give
32 (0.23 g, 78%) as a white solid. Mp 152-154 °C. 1H NMR
(d6-DMSO) δ 7.95 (d, J ) 8.4 Hz, 2H), 7.68 (d, J ) 8.4 Hz,
2H), 6.84 (s, 1H), 4.48 (t, J ) 5.2 Hz, 2H), 4.08-4.22 (m, 1H),

2192 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 9
Ranatunge et al.
Koboldt, C. M.; Perkins, W. E.; Seibert, K.; Veenhuizen, A. W.;
Zhang, Y. Y.; Isakson, P. C. Synthesis and Biological Evaluation
of the 1,5-Diarylpyrazole Class of Cyclooxygenase-2 Inhibitors:
Identification of 4-[5-(4-Methylphenyl)-3-(trifluoromethyl)-1H-
pyrazol-1-yl]benzenesulfonamide (SC-58635, Celecoxib). J . Med.
Chem. 1997, 40, 1347-1365. (b) Prasit, P.; Wang, Z.; Brideau,
C.; Chan, C.-C.; Charleson, S.; Cromlish, W.; Ethier, D.; Evans,
J . F.; Ford-Hutchinson, A. W.; Gauthier, J . Y.; Gordon, R.; Guay,
J .; Gresser, M.; Kargman, S.; Kennedy, B.; Leblanc, Y.; Leger,
S.; Mancini, J .; O’Neill, G. P.; Ouellet, M.; Percival, M. D.;
Perrier, H.; Riendeau, D.; Rodger, I.; Tagari, P.; Therien, M.;
Vikers, P.; Wong, E.; Xu, L.-J .; Young, R. N.; Zamboni, R.; Boyce,
S.; Rupniak, N., Forrest, M.; Visco, D.; Patrick, D. The discovery
of rofecoxib, [MK 966, Vioxx, 4-(4′-methylsulfonylphenyl)-3-
phenyl-2 (5H0-furanone], an orally active cyclooxygenase-2
inhibitor. Bioorg. Med. Chem. Lett. 1999, 9, 1773-1778.
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Gisham, M. B. Novel Nonsteroidal Antiinflammatory Drug
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M. B.; Cirino, G. A Diclofenac Derivative without Ulcerogenic
Properties. J . Pharmacol. 1994, 257, 249-255.
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Oxide-releasing Nonsteroidal Antiinflammatory Drug Acceler-
ates Gastric Ulcer Healing in Rats. Gastroenterology 1995, 109,
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Reducing Gastrointestinal Toxicity. J . Gastroenterol. Hepatol.
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3.42-3.49 (m, 2H), 3.02 (t, J ) 7.4 Hz, 2H), 1.82-2.00 (m, 4H),
1.70-1.82 (m, 4H), 1.19-1.38 (m, 2H); 13C NMR (d6-DMSO) δ
195.2, 149.5, 144.4, 143.0, 132.6, 129.6, 126.3, 106.6, 60.2, 58.1,
34.9, 32.9, 27.0, 24.8, 24.7; MS m/z 374 (M - OH), 392 (MH+).
LCMS (94.3%).
4-{1-Cycloh exyl-3-[4-(n itr ooxy)bu ta n oyl]p yr a zol-5-yl}-
ben zen esu lfon a m id e (33). Compound 33 was synthesized
in a manner similar to the synthesis of 6a using 32 (0.15 g,
0.38 mmol), fuming nitric acid (80 µL, 0.12 g, 1.92 mmol), and
acetic anhydride (0.28 mL, 0.31 g, 3.1 mmol) to give 33 (0.12
1
g, 74%) as a white solid. Mp 45-47 °C. H NMR (d6-DMSO) δ
8.05 (d, J ) 8.3 Hz, 2H), 7.51 (d, J ) 8.2 Hz, 2H), 6.80 (s, 1H),
4.75-4.90 (m, 2H), 4.59 (t, J ) 6.3 Hz, 2H), 3.90-4.20 (m, 1H),
3.21 (t, J ) 7.1 Hz, 2H), 2.15-2.24 (m, 2H), 1.75-1.92 (m, 4H),
1.92-2.15 (m, 2H), 1.40-1.60 (m, 2H), 1.18-1.32 (m, 2H);13C
NMR (d6-DMSO) δ 194.9, 149.9, 142.8, 142.6, 134.7, 129.8,
127.2, 107.1, 72.8, 59.1, 34.6, 33.4, 25.5, 25.1, 21.5; MS m/z
437 (MH+). LCMS (94.6%).
Ack n ow led gm en t. The authors wish to thank Dr.
Radha Iyengar at NitroMed, Inc., for helpful comments
and suggestions.
Su p p or tin g In for m a tion Ava ila ble: Experimental de-
tails and spectroscopic data for the compounds 6b-j, 17h , 22b-
i, 22k -r , 23b-i, 23b-ii, 23k , 23r , 26k -I, 26k -II, 27h -II. This
material is available free of charge via the Internet at http://
pubs.acs.org.
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