Design, synthesis, and biological evaluation of 1-(4-sulfamylphenyl)-3-trifluoromethyl-5-indolyl pyrazolines as cyclooxygenase-2 (COX-2) and lipoxygenase (LOX) inhibitors

Article abstract of DOI:10.1016/j.bmc.2008.01.047

A series of 20 novel 1-(4-sulfamylphenyl)-3-trifluoromethyl-5-indolyl pyrazolines were designed, synthesized, and screened in vitro for anti-inflammatory activity. These compounds were designed for evaluation as dual inhibitors of cyclooxygenases (COX-1 and COX-2) and lipoxygenases (LOX-5, LOX-12, and LOX-15) that are responsible for inflammation and pain. All pyrazoline molecules prepared are optically active and compounds that are more potent in COX-2 inhibitory activity (5a and 5f) were resolved by chiral column and each enantiomer was tested for cyclooxygenase inhibitory activity. Molecular modeling and comparison of molecular models of 5a enantiomers with that of celecoxib model shows that 5a (enantiomer-1) and 5a (enantiomer-2) have more hydrogen bonding interactions in the catalytic domain of COX-2 enzyme than celecoxib. Compounds 5a, 5e, and 5f showed moderate to good LOX-5 and LOX-15 inhibitory activity and this is comparable to that of celecoxib and more potent than rofecoxib.

Full text of DOI:10.1016/j.bmc.2008.01.047

Available online at www.sciencedirect.com
Bioorganic & Medicinal Chemistry 16 (2008) 3907–3916
Design, synthesis, and biological evaluation of
1-(4-sulfamylphenyl)-3-trifluoromethyl-5-indolyl pyrazolines
as cyclooxygenase-2 (COX-2) and lipoxygenase (LOX) inhibitors
M. V. Ramana Reddy,* Vinay K. Billa, Venkat R. Pallela, Muralidhar R. Mallireddigari,
Rengasamy Boominathan, Jerome L. Gabriel and E. Premkumar Reddy*
Fels Institute for Cancer Research, Temple University School of Medicine, 3307 North Broad Street, Philadelphia, PA
19140-5101, USA
Received 18 October 2007; revised 23 January 2008; accepted 23 January 2008
Available online 30 January 2008
Abstract—A series of 20 novel 1-(4-sulfamylphenyl)-3-trifluoromethyl-5-indolyl pyrazolines were designed, synthesized, and
screened in vitro for anti-inflammatory activity. These compounds were designed for evaluation as dual inhibitors of cyclooxygen-
ases (COX-1 and COX-2) and lipoxygenases (LOX-5, LOX-12, and LOX-15) that are responsible for inflammation and pain. All
pyrazoline molecules prepared are optically active and compounds that are more potent in COX-2 inhibitory activity (5a and 5f)
were resolved by chiral column and each enantiomer was tested for cyclooxygenase inhibitory activity. Molecular modeling and
comparison of molecular models of 5a enantiomers with that of celecoxib model shows that 5a (enantiomer-1) and 5a (enantio-
mer-2) have more hydrogen bonding interactions in the catalytic domain of COX-2 enzyme than celecoxib. Compounds 5a, 5e,
and 5f showed moderate to good LOX-5 and LOX-15 inhibitory activity and this is comparable to that of celecoxib and more potent
than rofecoxib.
ꢀ 2008 Elsevier Ltd. All rights reserved.
1. Introduction
rin and indomethacin which are non-selective and inhi-
bit both COX-1 and COX-2. Aspirin inhibits COX-1
more strongly than COX-24 and inhibition of COX-1
by aspirin reduces the production of PGE2 and PGI2
which has an adverse ulcerogenic effect.5
Cyclooxygenases (COXs) are key enzymes in the synthe-
sis of prostaglandin H2 which is a precursor for the bio-
synthesis of prostaglandins, thromboxanes, and
prostacyclins.1 COX enzymes exist in two isoforms,
cyclooxygenase-1 (COX-1) and cyclooxygenase-2
(COX-2).2 The COX-1 enzyme is constitutively ex-
pressed and is critical for protection of gastric mucosa,
platelet aggregation, and renal blood flow whereas the
COX-2 enzyme is inducible and expressed during
inflammation, pain and oncogenesis.3 Since COX-2 is
involved in inflammation and pain, molecules that inhi-
bit it’s enzymatic activity would be of therapeutic value.
Many non-steroidal anti-inflammatory drugs (NSAIDs)
were found to interact with these enzymes and inhibit
their enzymatic activity.4 These molecules include aspi-
Recently several new inhibitors were developed6–8 which
selectively inhibit the COX-2 enzyme without interfering
with COX-1 enzymatic activity. These molecules include
celecoxib,9 rofecoxib,10 and valdecoxib,11 all of which
inhibit COX-2 without the side effects observed with tra-
ditional NSAIDs. These selective inhibitors take advan-
tage of the larger enzymatic pocket in the COX-2 active
site where valine at amino acid position 523 has a smal-
ler side chain that accommodates the sulfur containing
side chains of the inhibitors, whereas the isoleucine res-
idue at position 523 in COX-1 has a larger side chain
that prevents docking of the inhibitor at the active site.12
This preferential binding of selective inhibitors to the
COX-2 enzyme over COX-1 enzyme prevents the side
effects as seen in non-selective inhibitors.13
Keywords: Pyrazolines; Pyrazole; COX-2; LOX; Enantiomers; Cyclo-
oxygenase-2 inhibitors; Lipoxygenase inhibitors; anti-inflammation;
Molecular modelling.
*
Corresponding authors. Tel.: +1 215 707 7336; fax: +1 215 707 1454
(M.V.R.R.); tel.: +1 215 707 4307 (E.P.R.); e-mail addresses:
rreddy@temple.edu; reddy@temple.edu
Aspirin is a unique NSAID that interacts with both
cyclooxygenases but inhibits COX-1 10- to 100-fold
0968-0896/$ - see front matter ꢀ 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2008.01.047

3908
M. V. Ramana Reddy et al. / Bioorg. Med. Chem. 16 (2008) 3907–3916
O2
S
In this paper, we describe the synthesis and biological
O2
S
evaluation of a novel class of 5-(3-indolyl)-1-(4-sulfa-
mylphenyl)-3-trifluoromethyl pyrazolines as dual inhibi-
tors of COXs and LOXs.
NH2
N
N
F3C
O
2. Chemistry
O
The synthesis of 5-(3-indolyl)-1-(4-sulfamylphenyl)-3-tri-
fluoromethyl pyrazolines is outlined in Schemes 1 and 2.
celecoxib
rofecoxib
O
O2
S
a
NH2
+
O
CF3
X
N
H
O
N
2
1
O
H
N
CF3
H2N
NH2
b
+
X
valdecoxib
N
H
S
O2
4
3
more effectively than the COX-2 enzyme.14 Aspirin’s
inhibitory activity is due to its ability to acetylate serine
residues positioned at 530 and 516 in COX-1 and COX-
2, respectively.15,16 Acetylation of these residues pre-
vents the positioning of arachidonic acid to its binding
site, thereby blocking the substrate to the active site of
oxygenation. Because of its dual inhibitory activity,
some of aspirin’s therapeutic advantages can be attrib-
uted to its ability to reduce inflammation by acetylating
COX-2 and prevent platelet aggregation and anti-
thrombosis by acetylating COX-1.17 Recent studies18
on selective COX-2 inhibitors revealed that patients with
heart disease are more prone to myocardial infarction
and this may be due to the TxA2/PGI2 imbalance cre-
ated by selective COX-2 inhibitors.19 Recently, Kalgut-
kar et al.20,21 have synthesized novel aspirin like
analogs with variations at acyl group, alkyl group, aryl
substitution pattern, and heteroatom substitution and
discovered a lead molecule that selectively acetylated,
and irreversibly inactivated, COX-2.
CF3
N
N
X
N
H
5
O2S
NH2
Scheme 1. Reagents and conditions: (a) ZnCl2/CH2Cl2, 3 h; (b)
ethanol, reflux 8 h.
H
O
O
a
b
+
X
O
X
F3C
N
N
H
H
1
6
7
Lipoxygenases (LOXs) belong to a class of non-heme
iron-containing enzymes which catalyze the hydroperox-
idation reaction of fatty acids to peroxides. Lipoxygenases
exist in three isoforms, lipoxygenase-5, lipoxygenase-12,
and lipoxygenase-15. Of the three isoforms, LOX-5 and
LOX-15 have been implicated in several undesirable
physiological effects. LOX-5 has been shown to be in-
volved in the production of leukotrienes which are known
to contribute to the progression of osteoarthritis, asthma,
and inflammation.22,23 Lipoxygenase-15 has been impli-
cated in the oxidation of low-density lipoprotein (LDL),
which ultimately causes atherosclerosis.24 Licofelone
(ML-3000), which is a dual COX/LOX-5 inhibitor, is a
potent anti-inflammatory agent without gastrointestinal
side effects and demonstrating platelet inhibitory and
anti-thrombotic effect.25 It clearly shows that a dual inhib-
itor of the COX/LOX enzymatic pathways offers a better
alternate approach in designing a new drug with excellent
safety profile and least side effects.
H
N
NH2
CF3
H2N
+
c
X
S
N
O2
H
4
3
CF3
N
N
X
N
H
5
O2S
NH2
Scheme 2. Reagents and conditions: (a) POCl3, DMF; (b) piperidine-
AcOH, THF, 3 h; (c) ethanol, reflux 8 h.

M. V. Ramana Reddy et al. / Bioorg. Med. Chem. 16 (2008) 3907–3916
3909
Table 1. In vitro COX-1 and COX-2 enzyme inhibition assay data for
the pyrazolines 5
The starting material for the synthesis of substituted
pyrazolenes 5 in Scheme 1 is (E)-1,1,1-trifluoro-4-(1H-in-
dol-3-yl)-but-3-en-2-one 3. Treatment of substituted in-
doles 1 with 4-ethoxy-1,1,1-trifluoro-3-buten-2-one 2 in
the presence of zinc chloride in dichloromethane pro-
duced 3 in quantitative yield. The NMR spectra of 3 re-
vealed that the vinylic fragments are in trans
CF3
N
N
X
configuration. Condensation of
3
with 4-sul-
N
H
famylphenylhydrazine hydrochloride 4 in ethanol gave
1-(4-sulfamylphenyl)-3-trifluoromethyl-5-indolyl pyraz-
olines 5 in quantitative yields.
O2S
NH2
Because trifluoroacetylvinylation of methoxy, amino,
carboxy, and nitro substituted indoles was unsuccess-
ful with 2, alternate method was developed to
synthesize 1,1,1-trifluoro-4-(3-substituted indolyl)-3-bu-
ten-2-ones. In this method, amino, nitro, carboxy, and
methoxy substituted indole-3-carboxaldehydes 6 were
treated with 1,1,1-trifluoroacetone 7 in tetrahydrofu-
ran in presence of catalytic amounts of piperidine
and acetic acid to give trans 1,1,1-trifluoro-4-(3-substi-
tuted indolyl)-3-buten-2-ones 3. Condensation addition
of 4-sulfamylphenylhydrazine hydrochloride to 3 pro-
duced 1-(4-sulfamylphenyl)-3-trifluoromethyl-5-indolyl
pyrazolines 5 (Scheme 2).
a
Compound
X
IC50 (l)
Selectivity indexb
COX-1 COX-2
5a
5b
H
5-F
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
1.4
>72
>8
>3
0
13.5
38.7
>100
>100
3.9
5c
5d
5-Cl
6-F
5e
6-Cl
7-Cl
0
5f
5g
>26
0
5-CN
6-Br
5-NH2
4-NH2
6-CN
6-NO2
>100
4.4
5h
5i
>23
>118
0
0.85
>100
>100
>100
6
5j
5k
0
5l
5m
0
Because all these molecules (5) have a chiral center at
5th position, they exist as optical isomers. Two of the
most active molecules were resolved by preparative
HPLC passing through a chiral column. The optical
rotation of the separated enantiomers was determined
on a polarimeter (Table 3). Usually the hydrogen on
the chiral carbon atom has interaction with the hydro-
gens adjacent to the chiral center. If the carbon adjacent
to the chiral center has one hydrogen, then the resulting
two enantiomers will have these two hydrogen atoms in
cis or trans position and can easily be distinguished by
NMR spectral analysis. But in this case, the carbon
atom next to the chiral center has two hydrogens and
would not be distinguished as cis and trans forms and
2-CH3, 6-Cl >100
>17
12
14
2
5n
5o
4-OCH3
6-NH2
5-NO2
5-COOH
7-NO2
7-NH2
H
>100
>100
>100
>100
>100
>100
>100
>100
8.7
7.5
5p
5q
57.2
>100
>100
2.4
0
5r
0
5s
>42
0
8
Celecoxib
>100
1.71
>60
a IC50 are means of two determinations.
b In vitro COX-2 selectivity index (COX-1 IC50/COX-2 IC50).
Table 2. In vitro LOX-5, LOX-12, and LOX-15 enzyme inhibition
assay data for 5
1
could not be distinguished by H NMR spectral data
(Table 4).
Compound
% Inhibition (10 lM)
LOX-5
LOX-12
LOX-15
5a
5e
41
51
94
89
11
5
À2
3
31
36
36
22
6
3. Results and discussion
5f
We have synthesized a series of 5-(3-indolyl)-1-(4-sulfa-
mylphenyl)-3-trifluoromethyl pyrazolines (5) and evalu-
ated their ability to inhibit COX-1, COX-2, LOX-5,
LOX-12, and LOX-15 enzymes in vitro using recombi-
nant enzymes. IC50 values for inhibition of ovine
COX-1 and COX-2 enzymes by these compounds were
determined by an Enzyme Immuno Assay (Table 1).
Celecoxib
Rofecoxib
7
À2
carboxy, and cyano moiety on the indole ring totally
inactivates the molecule. When the nitro group at 7th
position in 5r is replaced by an amino group (5s) or by
a chlorine atom (5f) the molecules show significant
improvement in COX-2 inhibition. Similarly when 5-ni-
tro group in the indole moiety of 5p is converted to 5-
amino (5i), the molecule became highly potent and
showed excellent inhibition of COX-2 enzyme with out
affecting the activity of COX-1. Comparison of 5b and
5c showed that smaller halogen atom at 5th position
on the indole ring enhances COX-2 enzyme inhibition
activity, whereas the presence of a larger bromine atom
at 6th position of the ring improves the inhibitory activ-
Inhibition of human LOX-5 from human PBML cells,
LOX-12 from human platelets, and LOX-15 from rabbit
reticulocytes were determined by EIA and spectrophoto-
metric quantitation (Table 2).
A comparison of the SAR data for the 5-(3-indolyl)-1-
(4-sulfamylphenyl)-3-trifluoromethyl pyrazolines (5a–
5s) against COX-1 and COX-2 enzyme inhibition
showed that the presence of a polar group such as nitro,

3910
M. V. Ramana Reddy et al. / Bioorg. Med. Chem. 16 (2008) 3907–3916
ity (5d, 5e, and 5h) of the compound. Also it is interest-
ing to compare 5i, 5j, 5o, and 5s, which reveals that the
amino group at any position on the ring except at 4th
(5j) renders the molecules quite active.
A molecular modeling study was performed where the
most selective COX-2 inhibitor 5a was docked in the
binding site of the COX-2 isoenzyme (Fig. 1). All molec-
ular modeling was performed on a Silicon Graphics Per-
sonal IRIS 4D/25 workstation. X-ray crystal structures
for COX-1 and COX-2 described by Loll and cowork-
ers26 and Kurumbail and coworkers,27, respectively,
were obtained from the Protein Data Bank. All calcula-
tions were performed using the DREIDING II all atom
force field and biografꢁ software (BIOSYM/Molecular
Simulations, San Diego, CA). Modified crystal struc-
tures for COX-1 and COX-2 were obtained by the addi-
tion of all heterogeneous hydrogen atoms in optimized
positions according to the biografꢁ software protocols.
In this series of compounds, the pyrazoline ring has a
chiral center on the 5th carbon atom and exists as opti-
cal isomers. In order to evaluate the activity of the indi-
vidual enantiomers, we have taken the racemic mixtures
of 5a and 5f and subjected them to chiral separation on
a high throughput HPLC system using a Chiralpak AD
250X4.6 mm column. Both enantiomers were isolated
and their optical rotations [a]D were calculated. The sep-
arated optically pure isomers (5a–A and 5f–A levorota-
tory-isomers, 5a–B and 5f–B dextrorotatory-isomers)
were then analyzed for COX-1 and COX-2 enzyme
inhibitory activity. In both cases, the l-isomers exhibited
an increased potency of several folds than their corre-
sponding racemic mixtures (Table 3). These data clearly
show that a pure single enantiomer may have a greater
binding affinity toward the catalytic domain of the en-
zyme than the racemic mixture.
Models of celecoxib and 5a and its enantiomers (Fig. 1)
were constructed using the organic builder contained
within the main biografꢁ program and were individually
docked into the active site of cyclooxygenase-2 by over-
laying the structure of each analog with the structure of
indomethacin derived from the original crystal struc-
ture. Modeling calculations were performed only allow-
ing for the movement of each analog within the active
site, while the atomic coordinates of COX-2 were held
constant. The calculations involved energy minimization
to convergence, limited molecular dynamics calculations
(5 ps), followed again by energy minimization to conver-
gence. By overlaying the crystal structure of COX-1 with
COX-2, the models of the analog:cyclooxygenase com-
plexes could be evaluated for binding efficiency to
COX-2 by evaluating hydrogen bonding interactions
and for a lack of binding efficiency to COX-1 as a result
of the steric hindrance in COX-1 due to the presence of
the longer side chain of Ile 523 compared to Val 523 in
COX-2. All inhibitors examined were sterically selective
for COX-2 over COX-1. As an example, the presence of
Arg 513 and Val 523 in COX-2 do not inhibit the bind-
ing of analog 5a (Fig. 1A), while the presence of His 513
and the longer side chain of Ile 523 in COX-1 resulted in
increased van der Waals interactions accounting for
the steric inhibition of the binding of 5a to COX-1
(Fig. 1B).
To understand the role of chiral center and its signifi-
cance in contribution of COX-2 inhibitory activity in
these pyrazolines, 5a is aromatized to pyrazole (8)
(Scheme 3) which led to the loss of chiral center. Anal-
ysis of the compound 8 in COX-1 and COX-2 in an
in vitro enzyme inhibition assay showed that aromatiza-
tion of pyrazoline 5a to pyrazole 8 inactivated the mol-
ecule thus preventing COX-2 inhibition (Table 1).
In vitro enzymatic assays using LOX-5, LOX-12, and
LOX-15 studies (Table 2) with 5a, 5e, and 5f showed
that these molecules have a moderate to good activity
toward LOX-5 and LOX-15 and very low activity to-
ward LOX-12. The LOX enzyme inhibition of these
compounds is comparable to celecoxib and better than
rofecoxib (Table 2).
Table 3. Optical activity and enzyme inhibition of 5a–A, 5a–B, 5f–A,
and 5f–B
Compound [a]D (degrees)
IC50 (lM)
Selectivity index
The protein main chain for COX-2 (Fig. 1A) and COX-
1 (Fig. 1B) is shown in light blue. Space filling models of
5a and residues involved in isotype selectivity are shown
in red and blue, respectively.
COX-1 COX-2
5a–A
5a–B
5f–A
5f–B
À94.690
+91.640
À70.769
À70.816
>100
>100
>100
>100
0.85
12.5
0.29
84
>119
>8
>345
>1
Examination of the molecular models for each analog
docked into COX-2 established a rubric for assessing
the binding efficiency of COX-2 specific analogs based
on the number and type of the possible hydrogen bond-
ing interactions suggested by the models (Table 5). The
data shown in Table 5 were constructed by analyzing ac-
tive site snapshots of molecular models of analog:COX-
2 complexes, similar to those shown in Figure 2. Note
the absence of hydrogen bonding interactions to His
90 and Q192 when celecoxib was docked with COX-2
(Fig. 2A) compared to the complex containing 5a (enan-
tiomer1) docked with COX-2 (Fig. 2B).
CF3
CF3
N
N
N
N
a
N
N
H
H
8
5a
O2S
O2S
NH2
NH2
The main chain atoms of the COX-2 protein are shown
in blue. Residues previously demonstrated to be in-
Scheme 3. Reagents and conditions: (a) 5% bromine-water, rt, 8 h.

M. V. Ramana Reddy et al. / Bioorg. Med. Chem. 16 (2008) 3907–3916
3911
Figure 1. Steric selectivity of COX-2 analogs.
Table 4. 1H NMR data of 5a–A, 5a–B, 5f–A, and 5f–B
Compound
NMR data (CDCl3)
5a–A
d 3.21(dd, J = 18.0, 6.8 Hz, 1H), 3.73 (dd, J = 18.0, 12.8 Hz, 1H), 4.64 (bs, 2H), 5.78 (dd, J = 12.8, 6.0 Hz, 1H), 7.07–7.67 (m,
9H), 8.20 (bs, 1H)
5a–B
5f–A
5f–B
d 3.21 (dd, J = 18.0, 6.8 Hz, 1H), 3.73 (dd, J = 18.0, 12.8 Hz, 1H), 4.64 (bs, 2H), 5.79 (dd, J = 12.8, 6.8 Hz, 1H), 7.07–7.67 (m,
9H), 8.21 (bs, 1H)
d 3.02 (dd, J = 18.0, 6.8 Hz, 1H), 3.71 (dd, J = 18.0, 12.8 Hz, 1H), 4.63 (bs, 2H), 5.91 (dd, J = 12.8, 6.8 Hz, 1H), 6.85–7.60 (m,
8H), 8.01(bs, 1H)
d 3.02 (dd, J = 18.0, 6.8 Hz, 1H), 3.71 (dd, J = 18.0, 12.8 Hz, 1H), 4.62 (bs, 2H), 5.91 (dd, J = 12.8, 6.8 Hz, 1H), 6.86–7.61 (m,
8H), 8.00 (bs, 1H)
Table 5. Hydrogen bonding interactions for COX-2 analogs
Analog
Q192
H90
R120
F518(aNH2)
5a (ent1)
5a (ent2)
Celecoxib
2.83A(SO2NH2)a
1.91A(SO2NH2)
2.13A(SO2NH2)
2.56A(CF3)
2.29A(CF3)
2.55A(CF3)
2.15A(SO2NH2)
2.58A(SO2NH2)
1.94A(SO2NH2)
***b
***
***
a Bold letters indicate the sulfamide group to which the hydrogen bond is formed.
b
, no hydrogen bond observed within 4 A of the designated residue.
***
Figure 2. Active site snapshots of molecular models of analog:COX-2 complexes.
volved in ligand binding are identified. 2A: celecoxib,
2B: 5a (enantiomer-1), 2C: 5a (enantiomer-2). Hydrogen
bonds are represented as dotted lines.
Because a chiral center is present in 5a at the point of
attachment of the pyrazoline group, this analog exists
in two different enantiomeric forms with the pyrazoline

3912
M. V. Ramana Reddy et al. / Bioorg. Med. Chem. 16 (2008) 3907–3916
Figure 3. Molecular models of the enantiomeric forms of analog 5a.
ring pointing out (enantiomer-1) or in (enantiomer-2) as
shown in Figure 3. Initial docking of 5a (enantiomer-2)
with the COX-2 protein resulted in major Van der
Waals contacts between the ligand and residues Glu
524, Arg 120, and Val 523 due to the opposite orienta-
tion of the pyrazoline group on 5a (enantiomer-1). In or-
der to successfully dock this analog into the active site of
COX-2, the intact enantiomer-2 was rotated to more
closely align the pyrazoline ring of this enantiomer with
that of enantiomer-1 as shown in Figure 3B. The molec-
ular model of the resulting enantiomer-2:COX-2 com-
plex was subjected to energy calculations and its active
site snapshot is shown in Figure 2C. Comparison of Fig-
ure 2B with Figure 2C suggests that the binding effi-
ciency of the 5a enantiomer-2 should be less than that
of enantiomer-1 for two reasons. First, a hydrogen bond
to His 90 is not observed when enantiomer-2 was
docked into the COX-2 active site. In addition, in the
presence of COX-2, the hydrogen bonds demonstrated
to be present between enantiomer-2 and Gln 192 or
Phe 518 involve the less electronegative sulfonamide
NH2 group as compared to the more electronegative sul-
fonamide SO2 group in the presence of enantiomer-1.
5. Experimental
5.1. COX-inhibition-EIA assay
Cyclooxygenase activity of ovine COX-1 and COX-2 was
assayedusingCOXinhibitoryscreeningassaykit(Cayman
Chemicals, MI). This assay directly measures PGF2a that
was produced by stannous chloride reduction of COX de-
rived PGH2 by enzyme immunoassay (EIA). This assay is
more accurate and reliable than the peroxide inhibition as-
say asshown by Gierse et al.28 All assays were conducted in
duplicate and IC50 values are the average of duplicate
determinations for each compound. In brief, for the inhibi-
tion assay, hematin reconstituted purified COX-1 and
COX-2 enzymes (six units) in a reaction buffer containing
Tris–HCl (0.1 M, pH 8.0), 5 mM EDTA, and 2 mM phe-
nol were pre-incubated at room temperature for 1 h with
inhibitor concentrations ranging from 0.001 to 100 mM
in DMSO followed by the addition of arachidonic acid
(100 lM) for 2 min at 37 ꢂC. Reactions were terminated
by adding 50 lL of 1 M HCl followed by the addition of
100 lL of stannous chloride. The final product
PGF2a formed was measured by EIA and IC50 values were
determined following the instructions given in the kit
manual.
Molecular models are shown for the enantiomers of 5a
before (Fig. 3A) and after (Fig. 3B) docking into the
COX-2 protein.
5.2. LOX-inhibition assay
Lipoxygenase 529 (LOX-5), Lipoxygenase 1230 (LOX-12),
and Lipoxygenase 1531 (LOX-15) activities were per-
formed by MDS Pharma Services, 158 Li-Teh Road, Pei-
tou, Taipei, Taiwan, following the procedures as
described. In these assays, the enzyme sources for LOX-
5, LOX-12, and LOX-15 are human PBML cells, human
platelets and rabbit reticulocytes, respectively. The sub-
stratesforLOX-5, LOX-12, andLOX-15usedintheassays
are endogenous arachidonic acid, 30 mM arachidonic acid
and 256 mM linoleic acid, respectively. The enzyme inhibi-
tion was quantitated by measuring LTB4, 12-HETE, and
15-HETE by EIA and spectrophotometrically.
4. Conclusions
In this report we have synthesized a series of novel
5-(3-indolyl)-1-(4-sulfamylphenyl)-3-trifluoromethyl pyr-
azolines and examined their activity against cyclooxy-
genases and lipoxygenases. Our results show that some
of these compounds show moderate to good activity
in COX-2, LOX-5, and LOX-15 inhibition assays. Sin-
gle enantiomers resolved from the racemate mixture
by a chiral column have exhibited much higher inhib-
itory activity than the parent compound. Aromatiza-
tion of the pyrazoline ring in 5a to pyrazole 8
resulted in total loss of activity indicating the impor-
tance of non-planar ring structure. Finally, the molec-
ular modeling suggests that active enantiomer
establishes more hydrogen bonding interactions with
the catalytic domain of COX-2 enzyme than the inac-
tive or less active isomer.
5.3. Chemistry
5.3.1. General information. Melting points were deter-
mined in an open capillary tube using a Mel-Temp electro
thermal melting point apparatus and are uncorrected.
Proton NMR (1H NMR) spectra were determined in

M. V. Ramana Reddy et al. / Bioorg. Med. Chem. 16 (2008) 3907–3916
3913
CDCl3, or DMSO-d6 solution on a Bruker Avance 400
spectrometer. Proton chemical shifts (d) are expressed in
parts per million (ppm) relative to tetramethylsilane as
an internal standard. Spin multiplicities are given as s (sin-
glet), d (doublet), bs (broad singlet), m (multiplet), and q
(quartet). Coupling constants (J) are given in hertz (Hz).
Liquid chromatography was performed with a forced
flow (flash chromatography) with Merck Grade Silica
gel (70–230 mesh). The solvents used for elution varied
depending on the compound and included either one or
a combination of the following: petroleum ether, ethyl
acetate, chloroform, and methanol. Analytical thin-layer
chromatography (TLC) was performed with Sigma–Al-
4H), 8.66 (d, J = 15.7, 1H), 13.09 (bs, 1H). Anal. calcd
for C12H7F4NO: C, 56.04; H, 2.74; N, 5.45. Found: C,
56.09; H, 2.69; N, 5.34.
5.3.2.4. 1,1,1-Trifluoro-4-(6-chloro-1H-indol-3-yl)-but-
1
3-en-2-one (3d). Yield 77%; mp 137–139 ꢂC; H NMR
(DMSO-d6) d 7.44(d, J = 15.7, 1H), 7.95–9.16 (m, 4H),
8.66 (d, J = 15.7, 1H), 13.09 (bs, 1H). Anal. calcd for
C12H7ClF3NO: C, 52.67; H, 2.58; N, 5.12. Found: C,
52.44; H, 2.29; N, 5.01.
5.3.2.5. 1,1,1-Trifluoro-4-(7-chloro-1H-indol-3-yl)-but-
1
3-en-2-one (3e). Yield 55%; mp 166–168 ꢂC; H NMR
˚
drich 0.25 mm silica gel plates (60 A), visualized under
(CDCl3) d 6.78 (d, J = 15.7, 1H), 6.88–7.67 (m, 4H),
8.04 (d, J = 15.5, 1H), 10.90 (bs, 1H). Anal. calcd for
C12H7ClF3NO: C, 52.67; H, 2.58; N, 5.12. Found: C,
52.31; H, 2.27; N, 5.07.
254 nm ultraviolet light or iodine spray. Elemental
analyses were obtained by Quantitative Technologies
Inc. (White House, NJ) and the results were mentioned
individually. All Yields were of purified product and were
not optimized. Celecoxib was prepared according to the
literature procedure.6 Reagents and solvents were
purchased from common suppliers and were used without
further purification. 5-Nitroindole carboxaldehyde,
5-carboxyindole carboxaldehyde, 7-nitroindole carboxal-
dehyde, 4-methoxyindole carboxaldehyde, 6-methoxyindole
carboxaldehyde, and 7-methoxyindole carboxal-
dehyde were synthesized according to the literature
methods.32 For molecular modeling, all calculations were
performed using the DREIDING II all atom force field
and biografꢁ software (BIOSYM/Molecular Simula-
tions, San Diego, CA). Modified crystal structures for
COX-1 and COX-2 were obtained by the addition of all
heterogeneous hydrogen atoms in optimized positions
according to the biografꢁ software protocols.
5.3.2.6. 1,1,1-Trifluoro-4-(5-cyano-1H-indol-3-yl)-but-
3-en-2-one (3f). Yield 62%; mp 95–97 ꢂC; 1H NMR
(DMSO-d6) d 7.43 (d, J = 15.7, 1H), 7.95–9.16 (m,
4H), 8.66 (d, J = 15.7, 1H), 13.09 (bs, 1H). Anal. calcd
for C13H7F3N2O: C, 59.10; H, 2.67; N, 10.60. Found:
C, 58.77; H, 2.30; N, 10.44.
5.3.2.7. 1,1,1-Trifluoro-4-(5-bromo-1H-indol-3-yl)-but-
1
3-en-2-one (3g). Yield 50%; mp 170–172 ꢂC; H NMR
(DMSO-d6) d 7.44 (d, J = 15.7, 1H), 7.95–9.16 (m,
4H), 8.65 (d, J = 15.7, 1H), 13.09 (bs, 1H). Anal. calcd
for C12H7BrF3NO: C, 45.31; H, 2.22; N, 4.40. Found:
C, 44.99; H, 1.99; N, 4.18.
5.3.2.8. 1,1,1-Trifluoro-4-(5-amino-1H-indol-3-yl)-but-
1
3-en-2-one (3h). Yield 58%; mp 161–165 ꢂC; H NMR
5.3.2. General procedure for the synthesis of substituted
(E)1,1,1-trifluoro-4-(1H-indol-3-yl)-but-3-en-2-one (3).33
Method A: To a solution of indole (5 mmol) and 4-ethoxy-
1,1,1-trifluoro-3-buten-2-one (5 mmol) in anhydrous
dichloromethane (10 mL) was added ZnCl2 (0.5 mmol).
The reaction mixture was stirred at rt for 3 h. Reaction
progress was monitored with TLC and, after completion,
the contents were cooled to 10 ꢂC and the precipitated
product was filtered, washed with CH2Cl2, and dried.
The crude products were recrystallized from hexane/etha-
nol to obtain pure 3.
(CDCl3) d 5.62–7.42 (m, 4H), 7.69 (d, J = 13.5, 1H),
7.71 (d, J = 13.5, 1H), 8.3 (bs, 1H). Anal. calcd for
C12H9F3N2O: C, 56.70; H, 3.57; N, 11.02. Found: C,
56.26; H, 3.12; N, 10.77.
5.3.2.9. 1,1,1-Trifluoro-4-(4-amino-1H-indol-3-yl)-but-
1
3-en-2-one (3i). Yield 70%; mp 102–104 ꢂC; H NMR
(CDCl3) d 5.72–7.95 (m, 4H), 7.88 (d, J = 13.6, 1H),
7.90 (d, J = 13.7, 1H), 8.40 (bs, 1H). Anal. calcd for
C12H9F3N2O: C, 56.70; H, 3.57; N, 11.02. Found: C,
57.13; H, 3.83; N, 11.13.
5.3.2.1. 1,1,1-Trifluoro-4-(5-fluoro-1H-indol-3-yl)-but-
3-en-2-one (3a). Yield 50%; mp 193–196 ꢂC; H NMR
(DMSO-d6) d 7.44 (d, J = 15.7, 1H), 7.95–9.16 (m,
4H), 8.66 (d, J = 15.7, 1H), 13.09 (bs, 1H). Anal. calcd
for C12H7F4NO: C, 56.04; H, 2.74; N, 5.45. Found: C,
55.88; H, 2.61; N, 5.23.
Method B.34 To a solution of Indole carboxaldehyde
(7.5 mmol) in dry THF (15 mL) was added glacial acetic
acid (0.5 mL) followed by piperidine (0.5 mL) under Ar-
gon atmosphere. Trifluoroacetone (30 mmol) was later
added to this reaction mixture over a period of 2–5 min
and stirred at room temperature for 2–3 h. The progress
of the reaction was monitored by TLC. After completion,
the reaction was quenched with saturated NH4Cl solution
and extracted with ethyl acetate (3 · 50 mL). The com-
bined extracts were dried over Na2SO4, filtered, and con-
centrated. Purification by column chromatography
eluting with 3:1 hexane/ethyl acetate afforded pure 3.
1
5.3.2.2. 1,1,1-Trifluoro-4-(5-chloro-1H-indol-3-yl)-but-
1
3-en-2-one (3b). Yield 62%; mp 163–165 ꢂC; H NMR
(DMSO-d6) d 7.44 (d, J = 15.7, 1H), 7.95–9.16 (m, 4H),
8.65 (d, J = 15.7, 1H), 13.09 (bs, 1H). Anal. calcd for
C12H7ClF3NO: C, 52.67; H, 2.58; N, 5.12. Found: C,
53.00; H, 2.67; N, 5.29.
5.3.2.10. 1,1,1-Trifluoro-4-(5-nitro-1H-indol-3-yl)-but-
1
5.3.2.3. 1,1,1-Trifluoro-4-(6-fluoro-1H-indol-3-yl)-but-
3-en-2-one (3c). Yield 48%; mp 191–194 ꢂC; H NMR
(DMSO-d6) d 7.43 (d, J = 15.7, 1H), 7.95–9.16 (m,
3-en-2-one (3j). Yield 50%; mp 246–249 ꢂC; H NMR
1
(DMSO-d6) d 7.43 (d, J = 15.7, 1H), 7.95–9.16 (m,
4H), 8.66 (d, J = 15.7, 1H), 13.09 (bs, 1H). Anal. calcd

3914
M. V. Ramana Reddy et al. / Bioorg. Med. Chem. 16 (2008) 3907–3916
for C12H7F3N2O3: C, 50.71; H, 2.48; N, 9.86. Found: C,
51.09; H, 2.70; N, 10.11.
calcd for C18H14ClF3N4O2S: C, 48.82; H, 3.19; N, 12.65.
Found: C, 48.49; H, 3.09; N, 12.45.
5.3.2.11. 1,1,1-Trifluoro-4-(5-carboxy-1H-indol-3-yl)-
but-3-en-2-one (3k). Yield 40%; mp 264–266 ꢂC; 1H
NMR (CDCl3) d 6.79 (d, J = 16.0, 1H), 7.25–8.40 (m,
4H), 8.01 (d, J = 15.5, 1H), 8.40 (bs, 1H, OH). Anal.
calcd for C13H8F3NO3: C, 55.13; H, 2.85; N, 4.95.
Found: C, 54.89; H, 2.33; N, 4.49.
5.3.3.4. 4-[5-(6-Fluoro-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5d). Yield
60%; mp 194–196 ꢂC; H NMR (DMSO-d6) d 2.59 (dd,
J = 8.5 Hz, 1H), 3.38 (dd, J = 8.5 Hz, 1H), 5.59 (dd,
J = 8.0 Hz,, 1H), 6.35–7.20 (m, 8H), 10.75 (bs, 1H). Anal.
calcd for C18H14F4N4O2S: C, 50.70; H, 3.30; N, 13.14.
Found: C, 50.22; H, 2.88; N, 12.54.
1
5.3.2.12. 1,1,1-Trifluoro-4-(7-nitro-1H-indol-3-yl)-but-
1
3-en-2-one (3l). Yield 55%; mp 228–230 ꢂC; H NMR
5.3.3.5. 4-[5-(6-Chloro-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5e). Yield
62%; mp 96–98 ꢂC; H NMR (DMSO-d6) d 3.09 (dd,
J = 8.5 Hz, 1H), 3.90 (dd, J = 8.5 Hz, 1H), 6.11 (dd,
J = 8.0 Hz, 1H), 7.03–8.12 (m, 8H), 11.29 (bs, 1H). Anal.
Calcd for C18H14ClF3N4O2S: C, 48.82; H, 3.19; N, 12.65.
Found: C, 48.44; H, 2.86; N, 12.24.
(CDCl3) d 6.98 (d, J = 16.0, 1H), 7.36–8.22 (m, 4H),
8.18 (d, J = 16.5, 1H). Anal. calcd for C12H7F3N2O3: C,
50.71; H, 2.48; N, 9.86. Found: C, 50.19; H, 2.21; N, 9.11.
1
5.3.2.13. 1,1,1-Trifluoro-4-(4-methoxy-1H-indol-3-yl)-
but-3-en-2-one (3m). Yield 60%; mp 188–192 ꢂC; 1H
NMR (CDCl3) d 3.93 (s, 3H), 7.16 (d, J = 16.0, 1H),
6.61–7.64 (m, 4H), 8.50 (d, J = 15.7, 1H). Anal. calcd
for C13H10F3NO2: C, 58.00; H, 3.74; N, 5.20. Found:
C, 57.59; H, 3.41; N, 5.01.
5.3.3.6. 4-[5-(7-Chloro-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5f). Yield
1
55%; mp 166–168 ꢂC; H NMR (DMSO-d6) d 3.03 (dd,
J = 8.5 Hz, 1H), 3.71 (dd, J = 8.5 Hz, 1H), 5.91 (dd,
J = 8.0 Hz, 1H), 6.86–7.60 (m, 8H), 8.0 (bs, 1H). Anal.
Calcd for C18H14ClF3N4O2S: C, 48.82; H, 3.19; N, 12.65.
Found: C, 48.33; H, 2.80; N, 12.31.
5.3.3. General procedure for the synthesis of substituted 4-[5-
(1H-Indol-3-yl)-3-trifluoromethyl-4,5-dihydropyrazol-1-
yl]-benzenesulfonamide (5). To a stirred solution of
substituted (E)1,1,1-trifluoro-4-(1H-indol-3-yl)-but-3-en-
2-one (3) (2.5 mmol) in ethanol (10 mL) was added (4-sul-
famylphenyl)hydrazine hydrochloride (4) (3 mmol) insmall
portions and the reaction mixture was refluxed for 8–10 h.
The progress of the reaction was monitored by TLC. After
completion, the reaction mixture was cooled to 25 ꢂC and
the solid separated out in most cases was filtered, washed
with ethanol, and dried. In some instances where solid
did not separate, the reaction mixture was poured into cold
water, extracted with ethyl acetate (2 · 100 mL), washed
with brine, dried over anhydrous Na2SO4, and evaporated
the solvent under reduced pressure. The oily product ob-
tained was triturated with 2-propanol and the solid sepa-
rated was filtered and dried. The crude products were
recrystallized from ethanol to give pure 5.
5.3.3.7. 4-[5-(5-Cyano-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5g). Yield
1
60%; mp 241–244 ꢂC; H NMR (DMSO-d6) d 3.15 (dd,
J = 8.5 Hz, 1H), 3.93 (dd, J = 8.5 Hz, 1H), 6.18 (dd,
J = 8.0 Hz, 1H), 7.09–8.11 (m, 8H), 11.73 (bs, 1H). Anal.
calcd for C19H14F3N5O2S: C, 52.65; H, 3.25; N, 16.15.
Found: C, 52.29; H, 3.39; N, 15.99.
5.3.3.8. 4-[5-(6-Bromo-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5h). Yield
1
68%; mp 112–114 ꢂC; H NMR (DMSO-d6) d 3.10 (dd,
J = 8.5 Hz, 1H), 3.90 (dd, J = 8.5 Hz, 1H), 6.12 (dd,
J = 8.0 Hz, 1H), 7.06–7.62 (m, 8H), 11.37 (bs, 1H). Anal.
calcd for C18H14BrF3N4O2S: C, 44.36; H, 2.89; N, 11.49.
Found: C, 43.34; H, 2.22; N, 10.73.
5.3.3.1. 4-[5-(1H-Indol-3-yl)-3-trifluoromethyl-4,5-dihy-
dropyrazol-1-yl]-benzenesulfonamide (5a). Yield 53%; mp
160–162 ꢂC; H NMR (CDCl3) d 3.22 (dd, J = 8.5 Hz,
1H), 3.74 (dd, J = 8.5 Hz, 1H), 4.60 (bs, 2H), 5.80 (dd,
J = 6.5 Hz, 1H), 7.08–7.69 (m, 9H), 8.19 (bs, 1H). Anal.
Calcd for C18H15F3N4O2S: C, 52.94; H, 3.70; N, 13.72.
Found: C, 53.09; H, 3.81; N, 13.90.
5.3.3.9. 4-[5-(5-Amino-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5i). Yield
50%; mp 152–156 ꢂC; H NMR (DMSO-d6) d 2.30 (bs,
2H), 2.94 (dd, J = 8.5 Hz, 1H), 3.70 (dd, J = 8.5 Hz, 1H),
6.15 (dd, J = 8.0 Hz, 1H), 6.81–8.17 (m, 8H), 11.66 (bs,
1H). Anal. calcd for C18H16F3N5O2S: C, 51.05; H, 3.80;
N, 16.53. Found: C, 50.99; H, 3.69; N, 16.33.
1
1
5.3.3.2. 4-[5-(5-Fluoro-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5b). Yield
60%; mp 193–196 ꢂC; H NMR (DMSO-d6) d 2.58 (dd,
J = 8.5 Hz, 1H), 3.41 (dd, J = 8.5 Hz, 1H), 5.95 (dd,
J = 6.5 Hz, 1H), 6.40–7.20 (m, 8H), 10.78 (bs, 1H). Anal.
Calcd for C18H14F4N4O2S: C, 50.70; H, 3.30; N, 13.14.
Found: C, 50.26; H, 3.09; N, 12.70.
5.3.3.10. 4-[5-(4-Amino-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5j). Yield
40%; mp 140–144 ꢂC; H NMR (DMSO-d6) d 2.50 (bs,
2H), 3.24 (dd, J = 8.5 Hz, 1H), 3.54 (dd, J = 8.5 Hz, 1H),
6.58 (dd, J = 8.0 Hz, 1H), 6.90–7.70 (m, 8H), 8.30 (bs,
1H). Anal. calcd for C18H16F3N5O2S: C, 51.05; H, 3.80;
N, 16.53. Found: C, 51.22; H, 3.69; N, 16.49.
1
1
5.3.3.3. 4-[5-(5-Chloro-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5c). Yield
62%; mp 163–165 ꢂC; H NMR (DMSO-d6) d 2.44 (dd,
J = 8.5 Hz, 1H), 3.23 (dd, J = 8.5 Hz, 1H), 5.46 (dd,
J = 6.5 Hz, 1H), 6.32–7.18 (m, 8H), 10.70 (bs, 1H). Anal.
5.3.3.11. 4-[5-(6-Cyano-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5k). Yield
55%; mp 222–224 ꢂC; H NMR (DMSO-d6) d 3.10 (dd,
J = 8.5 Hz, 1H), 3.74 (dd, J = 8.5 Hz, 1H), 6.40 (dd,
1
1

M. V. Ramana Reddy et al. / Bioorg. Med. Chem. 16 (2008) 3907–3916
3915
J = 8.0 Hz, 1H), 6.99–8.15 (m, 8H), 11.65 (bs, 1H). Anal.
Calcd for C19H14F3N5O2S: C, 52.65; H, 3.25; N, 16.15.
Found: C, 53.01; H, 3.36; N, 16.05.
2H), 3.12 (dd, J = 8.5 Hz, 1H), 3.92 (dd, J = 8.5 Hz, 1H),
6.13 (dd, J = 8.0 Hz, 1H), 6.45–7.80 (m, 8H), 10.32 (bs,
1H). Anal. calcd for C18H16F3N5O2S: C, 51.05; H, 3.80;
N, 16.53. Found: C, 50.99; H, 3.61; N, 16.66.
5.3.3.12. 4-[5-(6-Nitro-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5l). Yield
65%; mp 189–193 ꢂC; H NMR (DMSO-d6) d 3.20 (dd,
5.4. Computational details
1
J = 8.5 Hz, 1H), 3.94 (dd, J = 8.5 Hz, 1H), 6.23 (dd,
J = 8.0 Hz, 1H), 7.00–8.03 (m, 8H), 11.55 (bs, 1H). Anal.
Calcd for C18H14F3N5O4S: C, 47.68; H, 3.11; N, 15.45.
Found: C, 47.88; H, 3.01; N, 15.62.
For molecular modeling, all calculations were per-
formed using the DREIDING II all atom force field
and biografꢁ software (BIOSYM/Molecular Simula-
tions, San Diego, CA). Modified crystal structures for
COX-1 and COX-2 were obtained by the addition of
all heterogeneous hydrogen atoms in optimized posi-
tions according to the biografꢁ software protocols.
5.3.3.13. 4-[5-(6-Chloro-2-methyl-1H-indol-3-yl)-3-tri-
fluoromethyl-4,5-dihydro-pyrazol-1-yl]-benzenesulfonamide
(5m). Yield 60%; mp 120–124 ꢂC; 1H NMR (DMSO-d6) d
2.5 (s, 3H), 3.05 (dd, J = 8.5 Hz, 1H), 3.84 (dd, J = 8.5 Hz,
1H), 6.06 (dd, J = 8.0 Hz, 1H), 6.97–7.60 (m, 8H), 11.15
(bs, 1H). Anal. calcd for C19H16ClF3N4O2S: C, 49.95; H,
3.53; N, 12.26. Found: C, 49.45; H, 3.23; N, 12.06.
Models of celecoxib and 5a and its enantiomers (Fig. 1)
were constructed using the organic builder contained
within the main biografꢁ program and were individually
docked into the active site of cyclooxygenase-2 by over-
laying the structure of each analog with the structure of
indomethacin, derived from the original crystal struc-
ture. Modeling calculations were performed only allow-
ing for the movement of each analog within the active
site, while the atomic coordinates of COX-2 were held
constant. The calculations involved energy minimization
to convergence, limited molecular dynamics calculations
(5 psec.), followed again by energy minimization to
convergence.
5.3.3.14.
4-[5-(4-Methoxy-1H-indol-3-yl)-3-trifluoro-
methyl-4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5n).
Yield 68%; mp 156–158 ꢂC; 1H NMR (DMSO-d6) d 3.39
(dd, J = 8.5 Hz, 1H), 3.79 (dd, J = 8.5 Hz, 1H), 3.98 (s,
3H), 6.15 (dd, J = 8.0 Hz, 1H), 6.66–7.80 (m, 8H), 10.37
(bs, 1H). Anal. calcd for C19H17F3N4O3S: C, 52.05; H,
3.90; N, 12.77. Found: C, 52.44; H, 3.76; N, 11.57.
5.3.3.15. 4-[5-(6-Amino-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5o). Yield
1
50%; mp 208–210 ꢂC; H NMR (DMSO-d6) d 2.54 (bs,
Acknowledgments
2H), 2.94 (dd, J = 8.5 Hz, 1H), 3.95 (dd, J = 8.5 Hz, 1H),
6.19 (dd, J = 8.0 Hz, 1H), 6.55–8.40 (m, 8H), 11.05 (bs,
1H). Anal. calcd for C18H16F3N5O2S: C, 51.05; H, 3.80;
N, 16.53. Found: C, 50.04; H, 4.07; N, 13.69.
This work was supported by grants from Onconova
Therapeutics Inc., the Department of Defence (DAMD
17-02-1-0579), and NIH (CA 109820). We thank Dr.
Stacey Baker for editorial assistance. We also thank
Dr. Stanley Bell, Onconova Therapeutics Inc. for his
valuable comments and suggestions.
5.3.3.16. 4-[5-(5-Nitro-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5p). Yield
1
55%; mp 230–233 ꢂC; H NMR (DMSO-d6) d 3.02 (dd,
J = 8.5 Hz, 1H), 3.85 (dd, J = 8.5 Hz, 1H), 6.11 (dd,
J = 8.0 Hz, 1H), 6.91–8.23 (m, 8H), 11.72 (bs, 1H). Anal.
Calcd for C18H14F3N5O4S: C, 47.68; H, 3.11; N, 15.45.
Found: C, 47.71; H, 3.16; N, 14.75.
References and notes
1. Hamberg, M.; Samuelsson, B. Proc. Natl. Acad. Sci.
U.S.A. 1973, 70, 899.
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1
5.3.3.18. 4-[5-(7-Nitro-1H-indol-3-yl)-3-trifluoromethyl-
4,5-dihydropyrazol-1-yl]-benzenesulfonamide (5r). Yield
1
50%; mp 115–119 ꢂC; H NMR (DMSO-d6) d 3.14 (dd,
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5.3.3.19. 4-[5-(7-Amino-1H-indol-3-yl)-3-trifluoromethyl-
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