Novel 3,3a,4,5,6,7-Hexahydroindazole and Arylthiazolylpyrazoline derivatives as Anti-inflammatory Agents

Article abstract of DOI:10.1002/ardp.200300796

A novel series of 7-benzylidene-3,3a,4,5,6, 7-hexahydro-3-phenyl-2H-indazole substituted at the 2-position were synthesized. The reaction of 2,6-bis-benzylidenecyclohexanone (1) with thiosemicarbazide in the presence of NaOH afforded a mixture of the 3-H, 3a-H trans 2 and cis 2a diastereoisomers which have been separated by fractional recrystallization. Interaction of the first intermediate 2 with substituted phenacyl bromides, aromatic aldehydes and chloroacetic acid in presence of a mixture of acetic acid and acetic anhydride, and 2,3-dichloroquinoxaline yielded the corresponding 7-benzylidene-3,3a,4,5,6,7-hexahydro-3-phenyl-2H-indazole derivatives substituted at the 2-position with 4-aryl-2-thiazolyl 3 a, b, 5-arylidene-4,5-dihydro-4-oxo-2-thiazolyl 4a, b and thiazolo[4,5-b]quinoxalin-2-yl 5, respectively. Moreover, the other intermediates 3,5-diaryl-1-thiocarbamoyl-2-pyrazolines 7 a-d were reacted with the previously-mentioned reagents and gave the corresponding 3,5-diaryl-1-(4-aryl-2-thiazolyl)-2-pyrazolines 8 a-h, 3,5-diaryl-1-(5-arylidene-4,5-dihydro-4-oxo-2-thiazolyl)-2-pyrazolines 9 a-d and 3,5-diaryl-1-(thiazolo[4,5-b]quinoxalin-2-yl)-2-pyrazoline derivatives 10 a, b, respectively. Some of the newly prepared compounds were subjected to evaluation for their anti-inflammatory activity. The structures of the new compounds were confirmed by elemental analyses as well as ¹H-NMR, IR, and MS data.

Full text of DOI:10.1002/ardp.200300796

Arch. Pharm. Pharm. Med. Chem. 2003, 336, 551–559 Anti-inflammatory Hexahydroindazole and Arylthiazolylpyrazoline Derivatives 551
Magda N. A. Nasra,
Novel 3,3a,4,5,6,7-Hexahydroindazole and
Arylthiazolylpyrazoline derivatives as
Anti-inflammatory Agents
Shehta A. Saidb
a
Department of
Pharmaceutical Organic
Chemistry,
A novel series of 7-benzylidene-3,3a,4,5,6,7-hexahydro-3-phenyl-2H-indazole sub-
stituted at the 2-position were synthesized. The reaction of 2,6-bis-benzylidenecy-
clohexanone (1) with thiosemicarbazide in the presence of NaOH afforded a mixture
of the 3-H, 3a-H trans 2 and cis 2a diastereoisomers which have been separated by
fractional recrystallization. Interaction of the first intermediate 2 with substituted
phenacyl bromides, aromatic aldehydes and chloroacetic acid in presence of a mix-
ture of acetic acid and acetic anhydride, and 2,3-dichloroquinoxaline yielded the
corresponding 7-benzylidene-3,3a,4,5,6,7-hexahydro-3-phenyl-2H-indazole de-
rivatives substituted at the 2-position with 4-aryl-2-thiazolyl 3 a, b, 5-arylidene-4,5-
dihydro-4-oxo-2-thiazolyl 4 a, b and thiazolo[4,5-b]quinoxalin-2-yl 5, respectively.
Moreover, the other intermediates 3,5-diaryl-1-thiocarbamoyl-2-pyrazolines 7 a–d
were reacted with the previously-mentioned reagents and gave the corresponding
3,5-diaryl-1-(4-aryl-2-thiazolyl)-2-pyrazolines 8 a–h, 3,5-diaryl-1-(5-arylidene-4,5-
dihydro-4-oxo-2-thiazolyl)-2-pyrazolines 9 a–d and 3,5-diaryl-1-(thiazolo[4,5-b]qui-
noxalin-2-yl)-2-pyrazoline derivatives 10 a, b, respectively. Some of the newly pre-
pared compounds were subjected to evaluation for their anti-inflammatory activity.
The structures of the new compounds were confirmed by elemental analyses as
College of Pharmacy,
University of Mansoura,
Mansoura, Egypt
Department of
Pharmacology, College of
Pharmacy,
b
University of Mansoura,
Mansoura, Egypt
1
well as H-NMR, IR, and MS data.
Keywords: Arylthiazolylpyrazoline; Hexahydroindazole; Cyclooxygenase-2-inhibi-
tor; Anti-inflammatory activity
Received: February 4, 2003; Accepted: July 9, 2003 [FP796]
DOI 10.1002/ardp.200300796
side effects, particularly during extended periods of ther-
apy [5].
Introduction
Prostaglandins (PGs) elicit a variety of important benefi-
cial and untoward biological responses. Among the un-
desirable properties of prostaglandins is their ability to
induce pain, fever, and symptoms associated with the in-
flammatory response. Non-steroidal anti-inflammatory
drugs (NSAIDs) block the formation of prostaglandins
and have analgesic, antipyretic, and anti-inflammatory
activity [1].However, treatment with NSAIDs, particularly
chronically, often leads to disruption of beneficial pros-
taglandin-regulated processes [2, 3]. The principal side
effect associated with chronic administration of NSAIDs
are significant gastrointestinal irritations [4] and the for-
mation of life-threatening gastrointestinal ulcers, which
considerably limits the therapeutic potential of this class
of drugs. Alternative treatment of inflammation with glu-
cocorticoids may also lead to a variety of undesirable
A major mechanism of action of NSAIDs is lowering
prostaglandin production through inhibition of cyclooxy-
genase (COX) [6, 7].This enzyme exists in two isoforms,
one constitutive (COX-1), and the other inducible (COX-
2) [8, 9].The COX-1 isoform is constitutively expressed in
most tissues, and is involved in the physiological produc-
tion of prostaglandins, which are responsible for gastric
cytoprotection. The COX-2 isoform is induced by cy-
tokines, mitogens, and endotoxins [10, 11] in inflamma-
tory cells, and is responsible for the elevated production
of prostaglandins during inflammation.
Current NSAIDs inhibit both forms of the enzyme, with
many demonstrating a selectivity for COX-1.It is believed
that it is the inhibition of COX-1 that causes the side ef-
fects seen with NSAIDs. The discovery of COX-2 led to
the recognition that selective inhibitors of COX-2 would
constitute a novel approach to the treatment of inflam-
mation with diminished or no gastric side effects [12].
Correspondence:
Magda
Nasr,
Department
of
Pharmaceutical Organic Chemistry, College of Pharmacy,
University of Mansoura, Mansoura 35516, Egypt. Phone:
+20 50 224-7496, Fax: +20 50 224-7496, e-mail:
Magdaahnasr@yahoo.com
The chemical structures of COX-2 inhibitors are hetero-
genic leading to a further classification of this group.
© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

552 Nasr and Said
Arch. Pharm. Pharm. Med. Chem. 2003, 336, 551–559
Contrary to the classic NSAIDs, this new class of en-
zyme inhibitors is lacking a carboxylic group, thus affect-
ing COX-2 affinity by a different orientation within the en-
zyme without formation of a salt bridge in the hydropho-
bic channel of the enzyme. Selective COX-2 inhibitors
belong to different structural classes, one of which is the
vicinal diaryl heterocycles e.g., Celecoxib, Rofecoxib,
SC57666, and Dup-697 (Figure 1). These compounds
are characterized by a central carbocyclic or heterocy-
clic ring system bearing two vicinal aryl moieties, for opti-
mal activity one aromatic ring substituted with methylsul-
fonyl or sulfonamide substituent.These compounds rep-
resent the most important group of COX-2 inhibitors.Oc-
casionally, this structure is defined in the literature as a
“tricyclic compound” which is not really appropriate ac-
cording to chemical nomenclature. It can be assumed
that the heterocycle is responsible for the appropriate
orientation to the aromatic rings in space and finally for
the binding to the enzyme.A wide variety of heterocycles
can serve as a template for COX-2 inhibitors i.e., thia-
zole, furan, thiophene, and pyrrole but, at the moment,
pyrazole and cyclopentenone seem to be the most ap-
propriate tools for COX-2 specificity [13–23].
Pyrazolines [24–30], bicyclic pyrazolines [31], and qui-
noxalines [32] are also well-known for their pronounced
anti-inflammatory activity. Our interest in this area has
developed novel selective inhibitors of COX-2 that have
improved therapeutic properties relative to currently
used NSAIDs [33, 34]. In the present work, we detail our
strategy to obtain selective COX-2 inhibitors based on
the modification of the structure of the known potent vici-
nal diaryl carbocyclic and heterocyclic systems. Toward
that goal, it was thought worthwhile to synthesize new
series of pyrazoline and hexahydroindazole derivatives
to evaluate them as selective COX-2 inhibitors which ulti-
mately led to the identification of anti-inflammatory
agents with a greatly improved safety profile.
Results and discussion
Chemistry
The synthetic routes of the proposed compounds are
outlined in Schemes 1 and 2.Our initial goal in this study
was to prepare the N-substituted hexahydroindazole de-
rivatives 3–5.This was achieved through the preparation
Figure 1. Representative examples of selective COX-2 inhibitors and bicyclic pyrazoline derivatives as anti-inflamma-
tory agents.
© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Arch. Pharm. Pharm. Med. Chem. 2003, 336, 551–559 Anti-inflammatory Hexahydroindazole and Arylthiazolylpyrazoline Derivatives 553
Scheme 1.
of the starting compound 7-benzylidene-3,3a,4,5,6,7-
hexahydro-3-phenyl-2-thiocarbamoyl-2H-indazole (2)
(Scheme 1). It was reported that the reaction of 2,6-dia-
rylidenecycloalkanones with hydrazine and substituted
hydrazines yielded unsubstituted and 2-substituted bicy-
clic dihydropyrazoles having 3 and 3a-H of trans configu-
ration [35, 36]. In contrast to the above results, Jacquier
and Maury synthesized dihydropyrazoles derivatives in
a two-step reaction of 2-alkylidene and 2-benzylidene-
cycloalkanones with hydrazine and obtained both the cis
and trans diastereoisomers [37]. Moreover, reactions of
2,6-diarylidenecycloalkanones with thiosemicarbazide
under acidic catalysis yielded only one diastereoisomer
of the 3-H, 3a-H cis, while the reaction with semicar-
bazide afforded a mixture of trans and cis diastereo-
isomers, which have been separated [38, 39]. In the
present work, compound 2 was synthesized by the reac-
tion of 2,6-bis-benzylidenecyclohexanone (1) [40] with
thiosemicarbazide in presence of NaOH afforded a mix-
ture of the 3-H, 3a-H trans (major) 2 and cis (minor) 2 a
diastereoisomers which have been separated by frac-
tional recrystallization from methanol.However, column-
chromatographic separation was a suitable tool to iso-
late both components in a pure form. Moreover, they
were identified by thin-layer chromatography (TLC) anal-
ysis of the basic catalysis reaction products with an
© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

554 Nasr and Said
Arch. Pharm. Pharm. Med. Chem. 2003, 336, 551–559
Scheme 2.
authentic sample of the cis 2 a diastereoisomer pre-
pared through the acid catalyzed reaction procedure
[39].One of the two product components, apparently the
minor one, was matched properly with the cis isomer 2 a
and the other component, which seemed to be the major
one, is considered to be the trans diastereoisomer 2.The
confirmation of the trans isomer can also be achieved by
the melting point differences between the two products 2
and 2 a and by oxidation of the 2-thiocarbamoyl group in
compound 2 a with hydrogen peroxide according to the
previously described method [41] leading to the pub-
lished compound trans 7-benzylidene-2-carbamoyl-
3,3a,4,5,6,7-hexahydro-3-phenyl -2H-indazole (2 c) [38].
Two further aspects of stereo structures should be con-
sidered, the geometrical isomerism of the benzylidene
© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Arch. Pharm. Pharm. Med. Chem. 2003, 336, 551–559 Anti-inflammatory Hexahydroindazole and Arylthiazolylpyrazoline Derivatives 555
moiety and the conformation of the partly saturated con-
densed ring. Regarding the geometrical isomers, the Z-
isomer (S-cis Ar and N-1) is to be precluded due to unfa-
vorable steric structure.The S-cis (to N-1) position of the
hydrogen in the exocyclic =CH- group reveals a high
downfield shift of its 1H-NMR signal (this appears to over-
lap with the multiplets of the phenyl hydrogens) due to
anisotropic deshielding of the non-bonded electron pair
on N-1 [42]. The condensed, partly saturated six-mem-
bered ring can exsit in two preferred conformations.
These chair and boat-like forms with out-of-plane C-5
and C-7a atoms are both distorted approaching the sofa-
arrangement with coplanar C-7a.It is to be noted that the
inversion of the six-membered ring hardly influences the
envelope form of the pyrazoline ring (with an out-of-
plane C-3 atom) bearing the aryl (phenyl, substituted
phenyl, thienyl) group in a quasi-equatorial position [38].
with a variety of aromatic aldehydes and chloroacetic ac-
id in presence of a mixture of acetic acid and acetic anhy-
dride to produce the corresponding 2-(5-arylidene-4,5-
dihydro-4-oxo-2-thiazolyl)-7-benzylidene-3,3a,4,5,6,7-
hexahydro-3-phenyl-2H-indazole derivatives 4 a, b. Fur-
thermore, refluxing compound 2 with 2,3-dichloroqui-
noxaline [43] in absolute ethanol, gave the correspond-
ing fused 7-benzylidene-3,3a,4,5,6,7-hexahydro-3-
phenyl-2-(thiazolo[4,5-b]quinoxalin-2-yl)-2H-indazole
(5).
The second starting compounds 3,5-diaryl-1-thiocar-
bamoyl-2-pyrazolines (7 a–d) (Scheme 2) were pre-
pared.Refluxing the appropriate α,β-unsaturated carbo-
nyl compounds 6 a–d [44–46] with thiosemicarbazide in
presence of NaOH provided the requisite 7 a–d in good
overall yields. Similar reactions of 7 a–d with substituted
phenacyl bromides, different aromatic aldehydes and
chloroacetic acid, and 2,3-dichloroquinoxaline afforded
the corresponding 3,5-diaryl-1-(4-aryl-2-thiazolyl)-2-
pyrazolines 8 a–h, 3,5-diaryl-1-(5-arylidene-4,5-dihy-
dro-4-oxo-2-thiazolyl)-2-pyrazolines 9 a–d, and 3,5-di-
aryl-1-(thiazolo[4,5-b]quinoxalin-2-yl)-2-pyrazoline de-
rivatives 10 a, b, respectively.
The thiocarbamoyl moiety in compound 2 was subjected
to cyclocondensation reactions using different reagents.
Firstly, reaction of 2 with substituted phenacyl bromide
gave the corresponding 2-(4-aryl-2-thiazolyl)-7-benzyli-
dene-3,3a,4,5,6,7-hexahydro-3-phenyl-2H-indazole an-
alogues 3 a, b. On the other side, compound 2 reacted
Table 1. Physicochemical data of the new compounds.
R/(X)
R1
Mp °C
Rec. Sol*
Yield
(%)
Mol. Form.
3 a
3 b
4 a
4 b
7 a
7 b
7 c
7 d
8 a
8 b
8 c
8 d
8 e
8 f
8 g
8 h
9 a
9 b
9 c
9 d
10 a
10 b
Br
Cl
Br
Cl
–
–
–
–
–
–
–
–
Br
Cl
Br
Cl
Br
Cl
Br
Cl
Br
Cl
Cl
Br
–
182–185
175–177
170–172
180–182
213–215
218–220
280–282
155–157
225–227
208–210
220–222
203–205
295–297
167–169
200–202
175–177
188–190
110–112
235–237
115–117
235–237
210–212
A
E
E
E
68
61
58
60
71
74
72
78
68
65
62
63
65
67
66
68
52
55
58
60
72
75
C29H24BrN3S
C29H24ClN3S
C30H24BrN3OS
C30H24ClN3OS
C14H12BrN3OS
C14H12ClN3OS
C15H15N3OS
Br(O)
Cl(O)
CH3(O)
Cl(S)
Br(O)
Br(O)
Cl(O)
Cl(O)
CH3(O)
CH3(O)
Cl(S)
Cl(S)
Br(O)
Br(O)
Cl(O)
Cl(S)
Cl(O)
Cl(S)
A
Ac
EA
A
A
EA
A
M
E
M
Ac
E
E
A
AC
A
E
C14H12ClN3S2
C22H15Br2N3OS
C22H15BrClN3OS
C22H15BrClN3OS
C22H15Cl2N3OS
C23H18BrN3OS
C23H18ClN3OS
C22H15BrClN3S2
C22H15BrCl2N3S2
C23H15Br2N3O2S
C23H15BrClN3O2S
C23H15Cl2N3O2S
C23H15BrClN3OS2
C22H14N5OS
–
A
C22H14ClN5S2
*: Recryst. Solv.; A: acetone; Ac: aqueous acetic acid; E: ethanol; EA: ethyl acetate.
© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

556 Nasr and Said
Arch. Pharm. Pharm. Med. Chem. 2003, 336, 551–559
For the physicochemical data of these new compounds
see Table 1.
on the phenyl ring from electron-withdrawing to electron
donating, it nearly abolished the activity as in 7 c. It is
worthy to note that there is an analogy between the hex-
ahydroindazole series and the pyrazoline one.Thus, cy-
clization of the thiocarbamoyl group of compounds 7 into
a thiazole nucleus to give 8 did not alter the anti-inflam-
matory activity. However, 7 c gave an anomalous result
where cyclization greatly improved the anti-inflammato-
ry activity giving compound 8 f with high potency. On the
contrary, cyclization of 7 b, d to give 9 c, d, respectively,
decreased the activity. Moreover, the potency of 7 b, d
was increased by cyclization of the thiocarbamoyl moie-
ty to thiazolo[4,5-b]quinoxaline in 10 a, b.
Biological screening
Some of the newly synthesized compounds were tested
in vivo in order to evaluate their anti-inflammatory activity
against carrageenin induced paw edema at dose of 100
mg/kg using ketoprofen as a reference standard (Table
2). With the objective of identifying compounds with se-
lective COX-2 inhibition, we distinguished the selective
compounds of the present study by assessing in vivo ul-
cerogenic effects. One common feature of many of the
previously reported selective COX-2 inhibitors (Figure 1)
is the vicinal diaryl moities to a central carbocyclic or het-
erocyclic ring, for example: pyrazole, thiophene, cy-
clopentene, and benzofuran . In the present work, the
central ring is constructed so as to be either pyrazoline or
hexahydroindazole substituted in vicinal positions by two
carbocyclic, heterocyclic or fused heterocyclic residues.
It is interesting to point out that some compounds of the
present series exhibit good activity relative to the stand-
ard as shown in Table 2, ranging from 37 to 64 % edema
reduction, and some of them show low activity, with
17–18 % edema reduction. The major exception proved
to be 7 c being almost inactive, with 7 % edema reduc-
tion. Generally speaking, compounds with a central ring
hexahydroindazole are less potent than those with a
pyrazoline ring.Compound 2 with a thiocarbamoyl moie-
ty in vicinal position to a phenyl ring has little anti-inflam-
matory activity. Moreover, cyclization of the thiocar-
bamoyl group to thiazole ring did not appreciably affect
the potency as in 3 b. On the contrary, cyclization to give
thiazolo[4,5-b]quinoxaline moiety resulted in a signifi-
cant increase in potency with 37 % edema reduction as
in 5.On the other side, with the second analogous series
(Scheme 2), most compounds showed good anti-inflam-
matory activity, except compound 7 c. Using celecoxib
as a “template”, numerous sites of modification were ex-
plored. The initial modification was the replacement of
the vicinal phenyl groups in 1- and 5-positions by two
heterocyclic rings and, furthermore, the replacement of
the trifluoromethyl group at the 3-position by a phenyl
ring substituted by electron-withdrawing lipophilic group
(chloro or bromo) or electron donating group (methyl).
With the exception of 7 c, compounds 7 b–d exhibited
good anti-inflammatory activity. Among the biologically
active members of this series, compound 7 d shows high
anti-inflammatory activity with 50 % edema reduction.
The structural features of this compound are char-
acterized by having a thienyl group at the 2-position of
the pyrazoline ring vicinal to the thiocarbamoyl moiety in
addition to 4-chlorophenyl group at the 3-position. Re-
placement of a thienyl moiety by a furyl one decreased
the activity as in 7 b. Moreover, changing the substituent
Table 2. Anti-inflammatory activity of the tested com-
pounds assessed in comparison to ketoprofen as refer-
ence.
Compound
Mean
% Reduction
% increase in
of paw endema
paw weight ± SE from control group
Control
2
3 b
5
7 b
52
42
42
32 2*
31 2*
4
3
3
–
18
17
37
39
7
7 c
48
4
7 d
8 d
8 f
8 h
9 c
9 d
25 3*
31 2*
28 3*
26 2*
50
39
44
50
17
37
49
64
63
42
3
32 2*
26 2*
18 1*
10 a
10 b
Ketoprofen
18
1
All the test compounds and ketoprofen were given orally
in a dose of 100 mg/kg.
* Significantly different from the control group using stu-
dent’s t-test (p < 0.05).
Considering the potentialities, compound 10 b was stud-
ied in detail for its anti-inflammatory activity. Figure 2
shows the activity of three graded doses (25, 50, 100 mg/
kg) of compound 10 b and the standard drug ketoprofen.
It was found that 10 b has more or less comparable effi-
cacy with that of ketoprofen.The ulcerogenic liability da-
ta are compiled in Table 3. The selected compounds,
which are the most active in edema reduction, were test-
ed against celexocib, ketoprofen, and indomethacin.The
© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Arch. Pharm. Pharm. Med. Chem. 2003, 336, 551–559 Anti-inflammatory Hexahydroindazole and Arylthiazolylpyrazoline Derivatives 557
Table 3. Potential ulcerogenic effect of the test com-
pounds compared with ketoprofen, indomethacin, and
celecoxib.
Compound Dose (mg/kg)
Mean ulcer
index ± S.E.
Control
Ketoprofen
Vehicle
50
0
4.9 0.51*
11.2 1.40
1.3 0.20*$
5.4 0.43*
6.1 0.51*
3.9 0.26*
5.7 0.56*
6.2 0.57*
2.3 0.18*$
4.9 0.35*
2.2 0.19*$
2.1 0.20*$
Indomethacin
Celecoxib
5
5
50
50
50
50
50
50
50
7 b
7 d
8 d
8 f
8 h
9 d
10 a
10 b
Figure 2. The anti-inflammatory activity of ketoprofen
and compound 10 b at three graded doses (25, 50,
100 mg/kg) expressed as % reduction in paw edema
SE. No significant difference between 10 b and keto-
profen-treated groups using student’s t-test.
50
50
50
latter was used as a potent anti-inflammatory drug with
substantial ulcerogenic effect. It is obvious that in-
domethacin produced high incidence of gastric ulcera-
tion while ketoprofen produces less ulcerogenic effect,
and the selective COX-2 inhibitor celecoxib produced
minimal ulcerogenic effect.The synthesized compounds
were generally found to be safer from the view point of
ulcer induction except for compounds 7 b, 8 d, and 8 f. It
should be pointed out that compounds 8 h and 10 a, b
have significantly less ulcerogenic effect than ketopro-
fen. Moreover, their ulcerogenic effects were not signifi-
cantly different from the celecoxib-treated group. Mean-
while, the ulcerogenic effect of compound 5 is low, but
higher than ketoprofen.
* (p < 0.05) significantly different from indomethacin-
treated group using student’s t-test.
(p < 0.05) significantly different from ketoprofen-treat-
$
ed group using student’s t-test.
gastric ulceration and is almost equipotent with ketopro-
fen, thus it is considered to be a lead compound with a
potent anti-inflammatory and selective COX-2 inhibitory
activities.
Experimental
Therefore, it may be concluded that the compounds with
the most potent and selective COX-2 inhibitor as com-
pared with ketoprofen and celecoxib are characterized
by a central pyrazoline ring and have in vicinal positions
thiocarbamoyl, thiazolyl, or thiazolo[4,5-b]quinoxalinyl
moieties at the 1-position and the thiophene ring on the
adjacent carbon. In addition, it has in the 3-position a
phenyl ring substituted with an electron-withdrawing
group, e.g.a Cl atom, as in compounds 7 d,8 h, and 10 b.
Replacement of thiophene ring by furan, somewhat de-
creased the activity as in compounds 7 b, 8 d, and 10 a.
Furthermore, displacement of the electron-withdrawing
group on the phenyl ring in position 3 by an electron do-
nating markedly decreased the activity as in 7 c. In addi-
tion, changing the arylthiazole moiety in position 2 by
arylideneoxothiazole decreased the activity as in 9 c.
Moreover, replacement of the central pyrazoline ring by
hexahydroindazole moiety decreased the activity as in
compounds 2, 3 b, and 5. Compound 10 b gave minimal
Chemistry
Melting points (°C, uncorrected) were determined on a Fischer-
Johns apparatus (Fischer-Scientific, Pittsburgh, PA, USA). IR
spectra (KBr) were recorded on a Pye-Unicam SP1000 Spec-
trometer (í in cm–1) (Pye-Unicam Ltd., Cambridge, UK). H-
1
NMR spectra were recorded on a Varian EM-360 (90 MHz) in-
strument (Varian Inc., Palo Alto, CA, USA) using TMS as inter-
nalstandard(chemicalshiftsinppm,δunits).Massspectraldata
were recorded on a Varian MaT 112 A spectrophotometer.
Analytical TLC was applied to monitor the reactions using pre-
coated plates (Silica gel 60 F-245, Merck, Darmstadt, Ger-
many) and spots were visualized with UV light. The results of
elemental analyses (C,H,N) were within 0.4 % of the theoreti-
cal values.Thin layer chromatography was performed on silica
gel GLF plates, 250 microns.
trans-7-Benzylidene-3,3a,4,5,6,7-hexahydro-3-phenyl-2-thio-
carbamoyl-2H-indazole (2)
A mixture of 2,6-bis-benzylidenecyclohexanone (1) (2.74 g,
0.01 mol), thiosemicarbazide (1.82 g, 0.02 mol), and NaOH
(1.23 g, 0.025 mol) was refluxed in ethanol (25 mL) for 5 h.The
precipitate was filtered, dried and washed with cold ethanol.
© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

558 Nasr and Said
Arch. Pharm. Pharm. Med. Chem. 2003, 336, 551–559
Diastereoisomers 2 and 2 a were separated by fractional re-
crystallization from methanol to yield (48 %) 2:mp 165–167 °C;
IR:3410 (NH2), 1630 (C=N), 1580 (C=C), 1320 (C=S);1H-NMR
(DMSO-d6): 1.21–3.12 (m, 6 H, CH2), 3.41 (m, 1 H, 3a-H), 4.49
(br d, 1 H, 3-H), 7.40–8.21 (m, 11 H, ArH, CH=C), NH2 not iden-
tifiable. MS: m/z (%) M+ 347(3.9), 273 (100), 246 (13.1), 217
(26.2), 179 (34.8), 141 (25.6), 115 (48.9), 91 (26.0), 76 (42.4).
3,5-Diaryl-1-(5-arylidene-4,5-dihydro-4-oxo-2-thiazolyl)-2-pyra-
zolines (9 a–d)
These compounds were prepared from 7 a–d following the
same procedure used for preparation of 4 a, b. 9 a: IR: 1705
(C=O), 1630 (C=N), 1595 (C=C). MS: m/z (%) M+ 529 (64.8),
348 (26.9), 274 (23.2), 209 (31.5), 173 (56.5), 102 (21.5), 65
(100.0).
trans-2-(4-Aryl-2-thiazolyl)-7-benzylidene-3,3a,4,5,6,7-hexahy-
dro-3-phenyl-2H-indazoles (3 a, b)
3,5-Diaryl-1-(thiazolo[4,5-b]quinoxalin-2-yl)-2-pyrazoline (10 a,
b)
A mixture of compound 2 (3.47 g, 0.01 mol), 4-substituted
phenacyl bromide (0.01 mol) in absolute ethanol (20 mL) was
refluxed for 6 h. On cooling, the solid separated was filtered,
dried and recrystallized from the suitable solvent. 3 a: MS: m/z
(%) M+ 526 (2.9), 359 (27.9), 256 (83.0), 212 (19.5), 174
(100.0), 89 (32.3). 3 b: 1H-NMR (DMSO-d6): 1.72–3.00 (m, 6 H,
CH2), 3.41 (m, 1 H, 3a-H), 5.12 (br d, 1 H, 3-H), 7.20–8.21 (m,
16 H, ArH, CH=C). MS: m/z (%) M+ 481 (2.7), 313 (30.9), 210
(100.0), 168 (49.5), 77 (41.1).
Compounds 10 a, b were prepared following the same proce-
dure used for preparation of 5 except that compound 7 a–d was
used instead of compound 2. 10 a: 1H-NMR (DMSO-d6): 3.34
(d, 2 H, CH2), 5.51 (t, 1 H, CH), 6.80–7.74 (m, 11 H, ArH),
7.82–8.10 (br s, 2 H, NH2; D2O exchangeable).
Biological screening
Anti-inflammatory screening
The preliminary screening was done applying the procedure of
Winter et al. [47] using groups of albino rats weighing
100–120 g each, 6 rats in each group. The compounds were
suspended in 0.5 % carboxymethylcellulose (CMC) and given
to the rats orally in a dose of 100 mg/kg. Ketoprofen was used
as a positive control (reference standard) given orally in a dose
of 100 mg/kg. Another animal group serving as a negative con-
trol received equivalent volume of the vehicle (0.5 % CMC) oral-
ly. One hour after drug administration, each rat was injected
with 0.05 mL of 1 % carrageenin solution into the plantar tissue
of the right hind paw.Four hours after carrageenin injection, the
animals were killed by cervical dislocation and both the right
and left hind paws were cut at a standard point and weighed.
The difference in weight between right and left paws was re-
corded for each animal. The percentage increase in weight of
the carrageenin-injected paw over the other paw was calculat-
ed and percentage reduction of edema from the control group
was calculated as a measure of activity.
trans-2-(5-Arylidene-4,5-dihydro-4-oxo-2-thiazolyl)-7-benzyli-
dene-3,3a,4,5,6,7-hexahydro-3-phenyl-2H-indazoles (4 a, b)
A mixture of 2 (1.39 g, 4 mmol), chloroacetic acid (0.57g,
6 mmol), various aromatic aldehydes (4 mmol) and anhydrous
sodium acetate (0.54 g) was refluxed in acetic anhydride (8 mL)
and acetic acid (10 mL) for 6 h.The mixture was poured into ice-
water, and the precipitate was collected by filtration, dried, and
recrystallized from the suitable solvent. 4 a: IR: 1703 (C=O),
1609 (C=N), 1585 (C=C). 1H-NMR (DMSO-d6): 1.26–3.23 (m,
6 H, CH2), 3.38 (br d, 1 H, 3a-H), 5.35 (m, 1 H, 3-H), 6.85–8.21
(m, 12 H, ArH, 2CH=C). MS: m/z (%) M+ 510 (4.7), 263 (37.4),
221 (52.7), 179 (25.3), 162 (17.4), 144 (20.9), 121 (25.9), 104
(58.1), 76 (100.0). 4 b: IR: 1705 (C=O), 1630 (C=N), 1585
(C=C).
trans-7-Benzylidene-3,3a,4,5,6,7-hexahydro-3-phenyl-2-
(thiazolo[4,5-b]quinoxalin-2-yl)-2H-indazole (5)
Ulcerogenic liability
A mixture of compound 2 (3.47 g, 0.01 mol), 2,3-dichloroqui-
noxaline (1.99 g, 0.01 mol) in absolute ethanol (15 mL) was re-
fluxed for 8 h.The solvent was evaporated under reduced pres-
sure. The residue was recrystallized from acetone to yield
2.93 g (62 %) of 5, mp 190–192 °C . IR: 1615 (C=N), 1590
(C=C); 1H-NMR (DMSO-d6): 1.52–2.39 (m, 6H, CH2), 3.40 (m,
1 H, 3a-H), 4.55 (d, 1 H, 3-H), 7.24–8.22 (m, 15 H, ArH, CH=C).
It was determined in male albino rats weighing 150-180 g fol-
lowing the method of Adami et al.[48].The rats were divided in-
to 13 groups, 6 rats each, were fasted for 12 h prior to the ad-
ministration of drugs while allowing free access to water. In-
domethacin suspended in 0.5 % CMC was given orally in a
dose of 5 mg/kg whereas ketoprofen and the other compounds
were administered in a dose of 50 mg/kg.The dose was repeat-
ed daily for 5 days.The animals were sacrified 8 h after the last
drug treatment by overdose of ether. The stomach was re-
moved, rinsed with physiological saline, opened along the
greater curvature and studied with hand lens (× 10 magnifica-
tion). Ulcer index of each animal was expressed according to
the sum of the length of lesions on the basis of Adami et al.
3,5-Diaryl-1-thiocarbamoyl-2-pyrazolines (7 a–d)
A mixture of compounds (6 a–d) (0.01 mol), thiosemicarbazide
(0.91 g, 0.01 mol), and NaOH (1.23 g, 0.025 mol) was refluxed
in absolute ethanol (25 mL) for 4 h. On cooling, the product ob-
tained was collected by filtration, dried and recrystallized from
the appropriate solvent. 7 a: IR: 3415 (NH2), 1630 (C=N), 1580
1
(C=C), 1295 (C=S). H-NMR (DMSO-d6): 3.36 (d, 2 H, CH2),
5.52 (t, 1 H, CH), 6.85–7.71 (m, 7 H, ArH), 7.80–8.00 (br s, 2 H,
NH2; D2O exchangeable). 7 d: IR: 3450 (NH2), 1620 (C=N),
1
1580 (C=C), 1229 (C=S). H-NMR (DMSO-d6): 3.31 (d, 2 H,
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