Synthesis and anti-inflammatory activity of novel (substituted)benzylidene acetone oxime ether derivatives: Molecular modeling study

Article abstract of DOI:10.1016/j.ejmech.2009.12.041

Herein, we report the design, synthesis, and pharmacological properties of a series of substituted benzylidene acetone oxime ether derivatives from the corresponding oxime derivatives. All the newly synthesized compounds were investigated in vivo for their anti-inflammatory activities using carrageenin-induced rat paw oedema model. Among the compounds examined, compounds 5b and 7a showed the highest activity, nearly equivalent to that of the standard drug diclofenac sodium. Hence, they were screened for their analgesic activities using acetic acid-induced writhing model in mice and also, their ulcerogenic effects were studied. Compound 7a was found to possess significant anti-inflammatory and analgesic activities with negligible ulcerogenic effect. Docking study of the synthesized compound 7a into the active site of COX-1 and COX-2 revealed a similar binding mode to SC-558, a selective COX-2 inhibitor.

Full text of DOI:10.1016/j.ejmech.2009.12.041

European Journal of Medicinal Chemistry 45 (2010) 1403–1414
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and anti-inflammatory activity of novel (substituted)benzylidene
acetone oxime ether derivatives: Molecular modeling study
Mohammed I. El-Gamal a, Said M. Bayomi a, Saadia M. El-Ashrya, Shehta A. Said b, Alaa A.-M. Abdel-Aziz c,
,
Naglaa I. Abdel-Aziz a
*
a Department of Medicinal Chemistry, Faculty of Pharmacy, University of Mansoura, Mansoura 35516, Egypt
b Department of Pharmacology, Faculty of Pharmacy, University of Mansoura, Mansoura 35516, Egypt
c Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 4 July 2009
Received in revised form
5 December 2009
Accepted 18 December 2009
Available online 28 December 2009
Herein, we report the design, synthesis, and pharmacological properties of a series of substituted ben-
zylidene acetone oxime ether derivatives from the corresponding oxime derivatives. All the newly
synthesized compounds were investigated in vivo for their anti-inflammatory activities using carra-
geenin-induced rat paw oedema model. Among the compounds examined, compounds 5b and 7a
showed the highest activity, nearly equivalent to that of the standard drug diclofenac sodium. Hence,
they were screened for their analgesic activities using acetic acid-induced writhing model in mice and
also, their ulcerogenic effects were studied. Compound 7a was found to possess significant anti-
inflammatory and analgesic activities with negligible ulcerogenic effect. Docking study of the synthe-
sized compound 7a into the active site of COX-1 and COX-2 revealed a similar binding mode to SC-558,
a selective COX-2 inhibitor.
Keywords:
Benzylidene acetone oxime ether
derivatives
Anti-inflammatory activity
Molecular modeling study
Ó 2009 Elsevier Masson SAS. All rights reserved.
1. Introduction
COX selective inhibitors from flurbiprofen (A) [7] and indomethacin
(B) [8] have been published (Fig. 1). These strategies introduced the
Inflammation is a normal response to any noxious stimulus that
threatens the host and may vary from a localized response to
a generalized one [1]. The inflammatory process protects our body
from diseases by releasing cells and mediators that combat foreign
substances and prevent infection [2]. In 1971 [3], the role of pros-
taglandins (PGs) in the inflammatory process was observed. PGs are
synthesized from arachidonic acid which is released by the action
of phospholipase A2 on damaged tissues. Arachidonic acid is con-
verted by cyclooxygenase (COX) enzymes to cyclic PGG2 and PGH2
which cause vasoconstriction and pain. They, in turn, are converted
to PGE2 and PGF2a which cause vasodilatation and pain [4].
Two isoenzymes of cyclooxygenase were postulated, cyclo-
oxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). COX-1 is
a constitutive enzyme and is responsible for the production of the
basic level of PGs. Inhibition of this enzyme byall older, non-selective
non-steroidal anti-inflammatory drugs is primarily responsible for
a number of their side effects [5]. However, the existence of COX-2
enzyme was confirmed [5]. It is an inducible enzyme which is
induced in response to the release of several proinflammatory
mediators, leading to the inflammatory non-selective NSAID
response and pain [6]. To our knowledge, several attempts to derive
desired selectivity by systematic structural modification of the lead
NSAIDs. Alternatively, selectivity may be introduced by using the
available information on the tricyclic COX-2 selective inhibitors
(Fig.1) structurally related to SC-558 (C) [9]. Thus, there was an active
search for the development of specific inhibitors of COX-2 enzyme.
In this context, the present work describes the synthesis and the
investigation of the analgesic and anti-inflammatory properties of
new substituted benzylidene acetone oxime ether derivative (D)
(Fig.1). Our strategy for the synthesis of such derivatives is based on
the modification of the structure of the known potent non-selective
NSAID inhibitor. The strategy is intended to obtain potent anti-
inflammatory activity without ulcerogenic effects using traditional
medicinal chemistry techniques motivated by the comparative
modeling of COX-1 and -2 complexed with A and C together with
the available pharmacophore.
2. Results and discussion
2.1. Chemistry
2.1.1. Synthesis of compounds 1–11(Scheme 1)
Aldol condensation of benzaldehyde or its derivatives with
acetone was performed in the presence of aqueous ethanolic
* Corresponding author. Tel./fax: þ20 502247496.
E-mail address: Naglaabdalaziz2005@yahoo.com (N.I. Abdel-Aziz).
0223-5234/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2009.12.041

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M.I. El-Gamal et al. / European Journal of Medicinal Chemistry 45 (2010) 1403–1414
Fig. 1. Representative examples of non-selective (A, B) and selective (C) COX inhibitors and the general structure of the synthesized substituted benzylidene acetone oxime ether
derivatives (D).
sodium hydroxide to give the corresponding E-4-arylbut-3-en-2-
ones [10–14]. The latter chalcone derivatives reacted with
hydroxylamine hydrochloride in ethanol in the presence of sodium
hydroxide at room temperature to afford the corresponding oxime
derivatives 1a–c [15].
presence of anhydrous potassium carbonate gave ethyl {[((E)-
4-arylbut-3-en-2-ylidene)amino]oxy}acetates 2a–c and ethyl
2-{[((E)-4-arylbut-3-en-2-ylidene)amino]oxy}propanoates 3a–c,
respectively.
Conversion of the ester derivatives 2 and 3 into different
carboxylic acid derivatives is outlined in Scheme 1 for example;
hydrolysis of compounds 2 and 3 using potassium hydroxide
Refluxing the appropriate oxime derivatives 1a–c with ethyl
chloroacetate or ethyl 2-bromopropionate in dry acetone in the
OH
N
CH3
R
1a-c
ClCH2COOC2H5
or BrCH(CH3)COOC2H5
Acetone/ K2CO3
O
O
O
O
NHNH2
OC2H5
N
N
X
X
O
O
NH2NH2.H2O
EtOH
CH3
10,11a-c
CH3
OH
N
R
2,3a-c
R
X
CH3
4,5a-c
(CH3)2CHNH2
EtOH
NH4OH
EtOH
R
O
O
O
O
NH2
NHCH(CH3)2
N
N
X
X
CH3
8,9a-c
CH3
R
6,7a-c
R
R = H(a), Cl(b), OCH3(c)
X = H(2,4,6,8,10), CH3(3,5,7,9,11)
Scheme 1. Synthesis of aminooxy (acetic acid, propanoic acid, acetamide, propanamide, acetohydrazide and propanoic acid hydrazide) derivatives.

M.I. El-Gamal et al. / European Journal of Medicinal Chemistry 45 (2010) 1403–1414
1405
followed by neutralization with 10% hydrochloric acid afforded the
corresponding carboxylic acids 4,5a–c. Reaction of the ester
compounds 2 and 3 with ammonia afforded primary amide deriv-
atives 6,7a–c while reacting with isopropylamine afforded the cor-
responding secondary aliphatic amide derivatives 8,9a–c. Synthesis
of the hydrazide derivatives 10,11a–c was carried out by refluxing
compounds 2 and 3, respectively with hydrazine hydrate in absolute
ethanol. The spectral and microanalytical data for compounds
2–11a,b,c were consistent with their chemical structures.
Compounds 5b and 7a were studied in detail for their anti-
inflammatory activities in comparison with diclofenac sodium
using three graded doses (Table 2) and the ED50 was calculated,
29.92 mg/kg for compound 5b and 34.30 mg/kg for compound
7a. On the other hand the ED50 for diclofenac sodium was
30.65 mg/kg.
2.2.2. Analgesic activity
The analgesic activity of compounds 5b and 7a was studied by
using acetic acid-induced writhing test in mice. Compound 5b
showed lower analgesic activity than diclofenac sodium while
compound 7a showed analgesic potency about half the analgesic
effect of diclofenac sodium (Table 3).
2.1.2. Synthesis of compounds 13–15 (Scheme 2)
The appropriate aniline derivatives reacted with chloroacetyl
chloride in glacial acetic acid in the presence of anhydrous sodium
acetate to afford 2-chloro-N-arylacetamides 12a–c [16–18]. Treat-
ment of the oxime derivatives 1a–c with sodium methoxide in
anhydrous methanol afforded oximate sodium salt intermediates
which were converted into N-aryl-{[((E)-4-arylbut-3-en-2-ylide-
ne)amino]oxy}acetamides 13–15a,b,c upon reacting with
compounds 12a–c in dry DMF. The structures of the isolated
products 13–15a,b,c were established on the basis of their
elemental and spectral analyses.
2.2.3. Potential ulcerogenicity
The potential ulcerogenic effects of compounds 5b and 7a were
studied in comparison with diclofenac sodium using the method of
Adami et al. Compound 5b showed ulcerogenic effect as diclofenac
sodium and this may be attributed to the presence of free carbox-
ylic group. On the other hand the amide derivative 7a showed
negligible ulcerogenic effect (Table 4).
2.2.4. Determination of acute toxicity (LD50
)
2.2. Biological activity
The LD50 for diclofenac sodium and compounds 5b and 7a was
calculated following the method of Litchfield and Wilcoxon. The
LD50 was 744.6 mg/kg with 95% confidence limits 536.7–
1033.1 mg/kg and 146.178 with 95% confidence limits 106.95–
199.79 mg/kg for the tested compounds and diclofenac sodium,
respectively. Therapeutic index was calculated by dividing LD50
over ED50, it was 24.89 for compound 5b, 20.10 for compound 7a
and 4.76 for diclofenac sodium. Hence, compounds 5b and 7a have
higher therapeutic index than diclofenac sodium and appear to be
relatively less toxic anti-inflammatory agents.
2.2.1. In vivo anti-inflammatory studies
All the newly synthesized compounds and diclofenac sodium, as
a reference drug, were subjected to in vivo anti-inflammatory
studies using carrageenin-induced rat paw oedema model. All the
tested compounds showed reasonable percentages of oedema
reduction of about 21.66% for compound 3c and 66.70% for
compound 5b (Table 1). The major exception proved to be
compound 4c being almost inactive, with 7.35% oedema reduction.
Generally speaking, carboxylic acids and primary amide derivatives
showed the highest anti-inflammatory activities among the tested
compounds especially propanoic acid derivatives 5 and prop-
anamides 7. Compounds 5b and 7a showed the highest anti-
inflammatory activity with 66.70% and 63.23% oedema reduction,
respectively. Esterification of the carboxylic acids 4 and 5 resulted
in a notable decrease in the activity. In most cases, the propanoic
acid derivatives were more active than the acetic acid derivatives.
2.3. Molecular calculation and results
2.3.1. Conformational analysis
In an attempt to gain a better insight on the molecular struc-
tures of the active compound 5b as a representative example,
conformational analysis of the target compound has been
OH
N
CH3
R
1a-c
NaOCH3
CH3OH
H
X
N
O
Cl
O-Na+
CH3
O
O
N
H
N
N
X
CH3
13-15a,b,c
12a-c
R
R
DMF
R = H(13), Cl(14), OCH3(15)
X = a(H), b(Cl), c(OCH3)
Scheme 2. Synthesis of N-aryl-{[((E)-4-arylbut-3-en-2-ylidene)amino]oxy}acetamide derivatives.

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M.I. El-Gamal et al. / European Journal of Medicinal Chemistry 45 (2010) 1403–1414
Table 1
Table 3
Results of anti-inflammatory activity of the tested compounds against carrageenin-
induced rat paw oedema in rats.
Results of analgesic activity of compounds 5b and 7a against acetic acid-induced
writhing in mice.
Compounds
Mean % increase in
% Inhibition of paw oedema
from control group
Compounds
Dose
(mg/kg)
No. of writhes in 20 min after
acetic acid treatment
% Inhibition of
number of writhes
from control group
paw weight ꢁ SEM
Control
Diclofenac
2a
2b
2c
3a
3b
3c
4a
4b
4c
5a
5b
5c
6a
6b
6c
7a
7b
7c
8a
8b
8c
9a
9b
29.13 ꢁ 1.03d
8.12 ꢁ 0.49*
–
(mean ꢁ S.E.M.)
72.13
29.76
26.23
22.14
33.20
44.52
21.66
45.62
50.57
7.35
Control
Diclofenac
5b
45.67 ꢁ 0.37
13.20 ꢁ 0.57
36.40 ꢁ 0.66
27.80 ꢁ 0.47
21.20 ꢁ 0.98
8.00 ꢁ 0.40
–
20.46 ꢁ 1.05*d
21.49 ꢁ 1.07*d
22.68 ꢁ 1.03*d
19.46 ꢁ 1.13*d
16.16 ꢁ 0.83*d
22.82 ꢁ 0.56*d
15.84 ꢁ 0.79*d
14.40 ꢁ 0.63*d
26.99 ꢁ 1.31d
17.23 ꢁ 0.96*d
9.70 ꢁ 0.94*
50
45
100
37
71.10
20.30
39.13
53.58
82.48
7a
100
40.85
66.70
45.38
49.71
50.77
38.21
63.23
57.54
58.53
30.93
28.49
41.68
37.38
42.84
27.53
29.01
21.76
24.44
56.27
43.49
38.76
35.43
28.66
49.64
29.45
40.89
48.16
42.91
43.32
37.25
not saddle point by the absence of negative eigen value of the
Hessian through frequency calculation. At this stage, calculations
at the AM1 level were considered in order to determine relative
energies of the syn- and anti-isomers of both trans- and
cis-isomers of arylideneoxime derivatives. The results show that
the occurrence of four isomeric conformations for 5b, each pair
5b-trans-Anti, 5b-cis-Anti and 5b-trans-Syn, 5b-cis-Syn (Fig. 2)
have approximately similar heat of formation and anti-conformers
was more stable than syn-conformers by 2 kcal/mol.
15.91 ꢁ 1.15*d
14.65 ꢁ 0.83*d
14.34 ꢁ 1.05*d
18.00 ꢁ 1.10*d
10.71 ꢁ 0.87*
12.37 ꢁ 0.78*d
12.08 ꢁ 0.74*d
20.12 ꢁ 1.04*d
20.83 ꢁ 0.73*d
16.99 ꢁ 0.98*d
18.24 ꢁ 0.65*d
16.65 ꢁ 0.73*d
21.11 ꢁ 0.83*d
20.68 ꢁ 0.95*d
22.79 ꢁ 1.14*d
22.01 ꢁ 1.07*d
12.74 ꢁ 1.12*d
16.46 ꢁ 0.95*d
17.84 ꢁ 1.37*d
18.81 ꢁ 0.88*d
20.78 ꢁ 0.84*d
14.67 ꢁ 1.37*d
20.55 ꢁ 0.94*d
17.22 ꢁ 1.29*d
15.10 ꢁ 0.98*d
16.63 ꢁ 0.42*d
16.51 ꢁ 1.02*d
18.28 ꢁ 1.22*d
2.3.2. ADME profiling
The bioavailability of the most active compounds 4b, 5b, 6b,
7a–c and 11b and the reference drug diclofenac was assessed using
ADME (absorption, distribution, metabolism, elimination) predic-
tion methods. In particular, we calculated the compliance of
compounds to the Lipinski’s rule of five [22]. This approach has
been widely used as a filter for substances that would likely be
further developed in drug design programs. Briefly, this simple rule
is based on the observation that most orally administered drugs
have a molecular weight ꢀ500, a log P ꢀ 5, hydrogen bond donor
sites ꢀ5 and hydrogen bond acceptor sites (N and O atoms) ꢀ10. In
addition, we calculated the total polar surface area (TPSA) since it
is another key property that has been linked to drug bioavailability.
Thus, passively absorbed molecules with a TPSA > 140 are thought
to have low oral bioavailability [23]. Molecules violating more than
one of these rules may have problems with bioavailability.
Predictions of ADME properties for studied compounds are given
in Table 5. The results show that all synthesized compounds
comply with these rules and even diclofenac shows no violation.
Theoretically, these compounds should present good passive oral
absorption and differences in their bioactivity cannot be attributed
to this property.
9c
10a
10b
10c
11a
11b
11c
13a
13b
13c
14a
14b
14c
15a
15b
15c
* Significant difference from control group using unpaired Student’s ‘‘t’’ test p < 0.05.
Significant difference from diclofenac-treated group using unpaired Student’s ‘‘t’’
test p < 0.05.
d
performed by use of the MMþ force field [19] (calculations in
vacuo, bond dipole option for electrostatics, Polak–Ribiere algo-
rithm, RMS gradient of 0.01 kcal/Å mol) as implemented in
HyperChem 5.1 [20]. The most stable conformer was fully opti-
mized with by AM1 semi-empirical molecular orbital calculation
[21]. The global minimum was confirmed as true minimum and
2.3.3. Docking studies
The level of ulcerogenic potential and anti-inflammatory
activities of compounds 5b and 7a prompted us to perform
molecular docking studies to understand the ligand–protein
interactions in detail. All the calculations were performed using
Table 2
Results of anti-inflammatory activity of compounds 5b and 7a against carrageenin-
induced rat paw oedema in rats at three graded doses.
Compounds
Dose
% Inhibition of paw oedema
from control group
ED50
Table 4
Ulcerogenic potential of compounds 5b, 7a and diclofenac sodium in mice.
mg/kg
mg/kg
Control
Diclofenac
–
Compounds
Average number
of ulcers
Mean sum of lengths
of elongated ulcer
30
50
75
30
45
75
30
37
75
46.00
72.13
80.20
45.12
66.70
75.25
37.73
63.23
69.10
30.65
29.92
34.30
mm ꢁ SEM
0.0
7.9 ꢁ 0.81
8.1 ꢁ 0.87
0.3 ꢁ 0.05*
5b
7a
Control
Diclofenac
5b
0.0
6
7
7a
2
*Significantly less than the diclofenac sodium treated group using unpaired Stu-
dent’s ‘‘t’’ test p < 0.05.

M.I. El-Gamal et al. / European Journal of Medicinal Chemistry 45 (2010) 1403–1414
1407
Fig. 2. Most stable conformers of the active compound 5b as a representative example with ball and cylinder rendering.
MOE 2008.10 software [24] installed on 2.0G Core 2 Duo. The
crystal structures of COX-1 and COX-2 enzymes complexed with
flurbiprofen [25] and SC-558 [26] [1EQH, 1CX2] were used for the
docking. The active site of the enzyme was defined to include
residues within a 10.0 Å radius to any of the inhibitor atoms. The
automated docking program of MOE was used to dock compounds
5b and 7a on the active sites of both COX-1 and COX-2 enzymes.
For each compound the most stable docking model was selected
according to the best scored conformation predicted by the MOE
scoring function. The complexes were energy-minimized with an
MMFF94 force field [27] till the gradient convergence 0.05 kcal/
mol was reached. The two compounds could dock into the active
site of COX-1 successfully. The binding energies of ꢂ40.17 and
ꢂ7.99 kcal/mol were obtained for 5b and 7a, respectively (Table 6,
Fig. 3). Compound 5b complexes with COX-1 showed the occur-
rence of two strong hydrogen bonds with Arg 120 and Tyr 355
with distances 2.63 Å and 2.40 Å, respectively. The lower interac-
tion energy observed for 7a rationalizes the insufficient binding of
amide fragment into the COX-1 active site than that of the
carboxylate fragment of 5b (Fig. 3). The insufficient binding can be
explained in terms of the occurrence of only one weak hydrogen
bond between the amide group and Arg 120 (3.28 Å) and the
absence of hydrogen bonding with Tyr 355. The hydrophobic
phenyl ring and conjugated pi-system of the two double bonds of
5b was surrounded by active site amino acid residues Tyr 385, Leu
352, Trp 387, Gly 526, Ala 527, Val 349, Ile 523, Met 522 and Ser
530. A similar hydrophobic interaction trend was observed for 7a
complexes with COX-1.
On the other hand, compounds 5b and 7a were modeled in the
active site of COX-2 enzyme (Table 6, Fig. 4). The binding energies
of ꢂ10.57 and ꢂ55.09 kcal/mol were obtained for 5b and 7a,
respectively. The carboxylate fragment of 5b formed a weak
hydrogen bonding interaction with Arg 120 (3.05 Å) which may be
attributed to the deep entrance of hydrophobic aromatic part into
the secondary pocket of COX-2 with hydrophobic interaction with
Ala 516, Val 523, Val 349 and Gly 354 and lacking the hydrogen
Table 5
Table 6
Calculated Lipinski’s rule of five for the most active compounds.
Docking results of compounds 5b and 7a into the active sites of COX-1 and COX-2.
Compd. no. % Inhibition of Parameter
paw oedemaa
Nviolationsg
Compd.
no.
Against COX-1a
H-bond
Against COX-2 a
H-bond
Log pb TPSAc MWd nONe nOHNHf
Eint.
Eint.
Diclofenac 72.13
4.56 49.32 292.15 3
3.22 58.89 267.71 4
2.03 64.69 232.28 4
2.08 73.92 262.30 5
2.70 64.69 266.72 4
0.955 76.71 247.29 5
2.34 64.69 252.70 4
2.85 58.89 253.68 4
2
1
2
2
2
3
2
1
0
0
0
0
0
0
0
0
b
b
(distance Å,
strength)
(kcal molꢂ1
)
(distance Å,
strength)
(kcal molꢂ1
)
5b
7a
7c
7b
11a
6b
4b
66.70
63.23
58.53
57.54
56.27
50.77
50.57
5b
7a
Arg 120 (2.63,
strong)
Tyr 355 (2.40,
strong)
Arg 120 (3.28,
weak)
ꢂ40.17
ꢂ7.99
Arg 120 (3.05,
weak)
ꢂ10.57
ꢂ55.09
His 90 (2.70,
strong)
Gln 192 (2.47,
strong)
Phe 518 (3.42,
weak)
a
Data taken from Table 1.
Calculated lipophilicity.
Total polar surface area.
Molecular weight.
Number of hydrogen bond acceptors.
Number of hydrogen bond donors.
b
c
d
e
f
a
Details of hydrogen bonding are explained in Figs. 3–5.
Interaction energy between the ligand and receptor.
g
b
Number of violations from Lipinski’s rule of five.

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M.I. El-Gamal et al. / European Journal of Medicinal Chemistry 45 (2010) 1403–1414
Fig. 3. Docking of compounds 5b (left panel) and 7a (right panel) into the active site of COX-1. Hydrogen bonds are shown in green.
Fig. 4. Docking of compounds 5b (left panel) and 7a (right panel) into the active site of COX-2. Hydrogen bonds are shown in green.
bond pattern which was observed with COX-1. On the other hand
compounds 7a produce an inverted mode of binding with COX-2
with a deep movement into the hydrophilic pocket. Unlike 5b, the
amide group of 7a is able to reach the hydrophilic pocket and is
involved in strong hydrogen bonding with His 90 (2.7 Å) and Gln
192 (2.47 Å) and weak hydrogen bonding with Phe 518 (3.42 Å).
Such interactions are almost essential for COX-2 inhibitory
activity, as exemplified by the binding interaction of SC-558, an
analogue of celecoxib co-crystallized in the COX-2 active site [26].
In addition, such interaction forces the phenyl ring to adopt
a specific orientation at the top of the channel. This moiety is
involved in hydrophobic interaction with Trp 387, Tyr 385, Val
523, Leu 352, Ser 353, Val 349, Phe 518, and Ala 527. The lateral
pocket of COX-2 would therefore be responsible for the COX-2
selectivity of 7a and contributed to stabilize the ligand–enzyme
complexes (Figs. 4 and 5).
approximately similar fashion as the pyrazolic prototype (SC-558).
Comparison of the interactions performed by SC-558 in the crystal
and the docked structure of 7a with COX-2 (Fig. 4) shows that the
amide group of 7a hydrogen bonds to the amino acid residue Gln
192 and Phe 518, similar to the sulfonyl moiety of the pharmaco-
phoric sulfonamide group pertaining to SC-558. Moreover, an
additional hydrogen bond was observed between the oxime
oxygen and His 90, while NH2 moiety of sulfonamide fragment
hydrogen bonded with Arg 513. Additionally, the two double bond
systems are positioned in the same region as p-sulfonamido-phenyl
ring of SC-558, while, the aromatic ring of 7a is close to the p-Br-
phenyl ring of SC-558 (C), in the aromatic region of the active site
lined by aromatic amino acid residues such as Phe 518, Tyr 385 and
Trp 387, among others. This result suggests extra interactions of 7a
in this hydrophobic pocket and indicates an inverted pharmaco-
phore compared to what has been described for 5b COX-1 inhibi-
tors. In short, the described interactions are typical of selective
inhibitors of COX-2, confirming the molecular design of the
reported class of analgesic and anti-inflammatory amide deriva-
tives [28].
The complex generated by docking studies of 7a with COX-2 and
superimposition with the structure of the selective inhibitor, SC-
558, co-crystallized with COX-2 [26], illustrated in Fig. 5, shows that
compound 7a can bind in the active site of this enzyme in
Fig. 5. Alignment of 7a (red) and selective inhibitor SC-558 (cyan) in the active site of COX-2. Hydrogen bonds are shown in green.

M.I. El-Gamal et al. / European Journal of Medicinal Chemistry 45 (2010) 1403–1414
1409
3. Conclusion
M
þ þ 2), 248.00 (9.90, Mþ þ 1), 247.00 (26.00, Mþ), 246.00 (32.90),
232.00 (0.30), 218.00 (2.10), 202.00 (0.30), 174.00 (0.30), 160.00 (6.90),
144.00 (100.00), 129.00 (5.70), 103.00 (46.90), 90.00 (0.30), 77.00
(28.60). Anal. calcd. for C14H17NO3 (%): C, 68.00; H, 6.93; N, 5.66. Found:
C, 67.92; H, 6.81; N, 5.94.
Different (substituted) benzylidene acetone oxime ether deriva-
tives were synthesized and screened for anti-inflammatory activity.
Compounds 5b and 7a with the highest anti-inflammatory activities
were subjected to analgesic and ulcerogenic studies. Compound 7a
showed negligible ulcerogenic effect with higher safety and better
therapeutic index than diclofenac sodium, so it appears promising.
Molecular docking studies further help in understanding the various
interactions betweenthe ligandsand enzymeactivesites indetailand
thereby help to design novel potent inhibitors. This result was
corroborated by molecular docking studies with ulcerogenic poten-
tial, which showed that this compound presents the pharmacophoric
requisites for COX-2 inhibition. Molecular docking studies further
supported the strong ulcerogenic inhibitory activity of 7a compared
to 5b and further help in understanding the various interactions
between the ligands and enzyme active sites in detail and thereby
help to design novel potent inhibitors.
4.2.2. Ethyl {[((E)-4-(4-chlorophenyl)but-3-en-2-ylidene)
amino]oxy}acetate (2b)
Yield, 70%; mp 59–62 ꢃC; IR (KBr) nmax/cmꢂ1 1741 (C]O), 1600
(C]N),1488 (C]C).1HNMR(CD3OD);
d1.33 (t, 3H, COOCH2CH3), 2.18 (s,
3H, CNCH3), 4.27 (q, 2H, COOCH2CH3), 4.63 (s, 2H, OCH2COO), 6.83 (d,1H,
Ar-CH]CH), 7.07 (d,1H, Ar-CH]CH), 7.40 (d, 2H, 20,60 Ar-H), 7.55 (d, 2H,
30,50 Ar-H). 13C NMR (CDCl3);
d 11.21 (CNCH3),14.95 (COOCH2CH3), 61.21
(COOCH2CH3), 70.98 (OCH2COO), 123.36 (Ar-CH]CH), 126.76 (40 Ar-C),
129.48 (30,50 Ar-C), 129.82 (20,60 Ar-C), 132.81 (10 Ar-C), 136.72 (Ar-
CH]CH), 157.53 (C]N), 170.31 (COOC2H5). Anal. calcd. for C14H16ClNO3
(%): C, 59.68; H, 5.72; N, 4.97. Found: C, 59.38; H, 6.10; N, 5.33.
4.2.3. Ethyl {[((E)-4-(4-methoxyphenyl)but-3-en-2-ylidene)
amino]oxy}acetate (2c)
4. Experimental
Yield, 65%; oil; IR (KBr) nmax/cmꢂ1 1742 (C]O), 1599 (C]N),
4.1. General
1491 (C]C). 1H NMR (CDCl3);
d 1.17 (t, 3H, COOCH2CH3), 2.01 (s, 3H,
CNCH3), 3.69 (s, 3H, OCH3), 4.10 (q, 2H, COOCH2CH3), 4.53 (s, 2H,
OCH2COO), 6.68 (d, 1H, Ar-CH]CH), 6.75 (d, 2H, 30,50 Ar-H), 7.06 (d,
1H, Ar-CH]CH), 7.27 (d, 2H, 20,60 Ar-H). Anal. calcd. for C15H19NO4
(%): C, 64.97; H, 6.91; N, 5.05. Found: C, 65.29; H, 6.55; N, 5.16.
Melting points were measured with a Fisher–Johns melting point
apparatus and are uncorrected. IR spectra were recorded on Matt-
son 5000 FT-IR spectrometer. 1H NMR spectra were determined
in CDCl3 or DMSO-d6 on FT-NMR spectrometer (200 MHz) Gemini
Varian using TMS as internal standard. Mass spectra were
measured on JEOL JMS-600H spectrometer. Elemental analysis
was carried out at the Microanalytical Center of Cairo University.
(E)-4-Phenylbut-3-en-2-one [13], (E)-4-(4-chlorophenyl)but-3-en-
2-one [10,14], (E)-4-(4-methoxyphenyl) but-3-en-2-one [10],
[((E)-4-phenylbut-3-en-2-ylidene)amino]hydroxide 1a [15], [((E)-
4-(4-chlorophenyl)but-3-en-2-ylidene)amino]hydroxide 1b [15],
[((E)-4-(4-methoxyphenyl)but-3-en-2-ylidene)amino] hydroxide 1c
[15], {[((E)-4-phenylbut-3-en-2-ylidene)amino]oxy}acetic acid 4a
[29], 2-chloro-N-phenylacetamide 12a [16,30], 2-chloro-N-(4-chlor-
ophenyl)acetamide 12b [16,18] and 2-chloro-N-(4-methoxyphenyl)
acetamide 12c [16,18]were prepared following the procedures
reported in the literature.
4.2.4. Ethyl 2-{[((E)-4-phenylbut-3-en-2-ylidene)
amino]oxy}propanoate (3a)
Yield, 40%; oil; IR (KBr) nmax/cmꢂ1 1739 (C]O), 1603 (C]N),
1488 (C]C). 1H NMR (CDCl3);
d 1.25 (t, 3H, COOCH2CH3), 1.48 (d,
3H, CHCH3), 2.10 (s, 3H, CNCH3), 4.20 (q, 2H, COOCH2CH3), 4.71 (q,
1H, CHCH3), 6.79 (d, 1H, Ph-CH]CH), 6.98 (d, 1H, Ph-CH]CH),
7.26–7.49 (m, 5H, Ar-H). Anal. calcd. For C15H19NO3 (%): C, 68.94; H,
7.33; N, 5.36. Found: C, 68.87; H, 7.65; N, 5.16.
4.2.5. Ethyl 2-{[((E)-4-(4-chlorophenyl)but-3-en-2-ylidene)
amino]oxy}propanoate (3b)
Yield, 40%; oil; IR (Nujol Mull) nmax/cmꢂ1 1741 (C]O), 1600
(C]N),1490 (C]C).1H NMR (CDCl3);
d 1.25 (t, 3H, COOCH2CH3),1.50
(d, 3H, CHCH3), 2.10 (s, 3H, CNCH3), 4.22 (q, 2H, COOCH2CH3), 4.74 (q,
1H, CHCH3), 6.80 (d, 1H, Ar-CH]CH), 7.04 (d, 1H, Ar-CH]CH), 7.28
(d, 2H, 30,50 Ar-H), 7.50 (d, 2H, 20,60 Ar-H). Anal. calcd. for C15H18ClNO3
(%): C, 60.91; H, 6.13; N, 4.74. Found: C, 60.67; H, 6.40; N, 4.65.
4.2. General method for synthesis of ethyl {[( (E)-4-arylbut-3-en-2-
ylidene)amino]oxy}acetates (2a–c) and ethyl 2-{[((E)-4-arylbut-3-
en-2-ylidene)amino]oxy}propanoates (3a–c) (Scheme 1)
A mixture of the appropriate oxime derivative 1a–c (0.05 mol),
ethyl chloroacetate (7.35 g, 0.06 mol) or ethyl 2-bromopropionate
(10.86 g, 0.06 mol) and anhydrous potassium carbonate (13.8 g,
0.10 mol) in dry acetone (25 mL) was heated under reflux for 24 h.
The reaction mixture was then filtered and the filtrate was evapo-
rated under reduced pressure. The residues of compounds 2a,b and
3c were crystallized from ethanol while those of compounds 2c and
3a,b were dissolved in methanol and then purified by preparative
TLC using benzene:ethyl acetate (5:1) as an eluting system.
4.2.6. Ethyl 2-{[((E)-4-(4-methoxyphenyl)but-3-en-2-ylidene)
amino]oxy}propanoate (3c)
Yield, 45%; mp 44–46 ꢃC; IR (KBr) nmax/cmꢂ1 1743 (C]O), 1601
(C]N),1493 (C]C).1H NMR (CDCl3);
d1.25 (t, 3H, COOCH2CH3),1.45 (d,
3H, CHCH3), 2.09 (s, 3H, CNCH3), 3.79 (s, 3H, OCH3), 4.18 (q, 2H,
COOCH2CH3), 4.68 (q,1H, CHCH3), 6.60 (d,1H, Ar-CH]CH), 6.87 (d, 2H,
30,50 Ar-H), 6.93 (d, 1H, Ar-CH]CH), 7.40 (d, 2H, 20,60 Ar-H). 13C NMR
(CDCl3);
d 11.35 (CN-CH3), 15.29 (COOCH2CH3), 17.97 (CHCH3), 56.59
(OCH3), 62.93 (COOCH2CH3), 79.47 (CHCH3), 116.10 (30,50 Ar-C), 124.55
(Ar-CH]CH), 130.15 (10 Ar-C), 131.15 (20,60 Ar-C), 135.88 (Ar-CH]CH),
159.48 (C]N), 162.33 (40 Ar-C), 175.54 (COOC2H5). Anal. calcd. for
C16H21NO4 (%): C, 65.96; H, 7.27; N, 4.81. Found: C, 65.84; H, 7.54; N, 4.73.
4.2.1. Ethyl {[((E)-4-phenylbut-3-en-2-ylidene)amino]oxy}acetate
(2a)
Yield, 73%; mp 55–56 ꢃC; IR (KBr) nmax/cmꢂ1 1739 (C]O), 1603
(C]N),1485 (C]C). 1H NMR (CD3OD);
d
1.33 (t, 3H, COOCH2CH3), 2.19
4.3. General method for synthesis of {[((E)-4-arylbut-3-en-2-
ylidene)amino]oxy}acetic acids (4b,c) and 2-{[((E)-4-arylbut-3-
en-2-ylidene) amino]oxy}propanoic acids (5a–c) (Scheme 1)
(s, 3H, CNCH3), 4.26 (q, 2H, COOCH2CH3), 4.72 (s, 2H, OCH2COO), 6.83
(d, 1H, Ph-CH]CH), 7.08 (d, 1H, Ph-CH]CH), 7.32–7.55 (m, 5H, Ar-H).
13C NMR (CD3OD);
d 9.15 (CN–CH3), 13.15 (COOCH2CH3), 60.72
(COOCH2CH3), 70.31 (OCH2COO), 124.67 (Ar-CH]CH), 126.63 (40Ar-C),
129.48 (30,50 Ar-C), 129.82 (20,60 Ar-C), 132.81 (10 Ar-C), 136.72 (Ar-
CH]CH), 157.53 (C]N), 170.31 (COOC2H5). MS m/z (%) 249.00 (1.6,
A mixture of compound 2,3a–c (0.05 mol) and potassium
hydroxide (3.36 g, 0.06 mol) in ethanol (30 mL) was stirred at room
temperature for 48 h. The solvent was evaporated under reduced

1410
M.I. El-Gamal et al. / European Journal of Medicinal Chemistry 45 (2010) 1403–1414
pressure and the residue was triturated with water and then
filtered. The filtrate was neutralized with 10% HCl and extracted
with diethyl ether (3 ꢄ 15 mL). The extract was evaporated under
reduced pressure and the obtained residues for compounds 4b,c
and 5a,c were crystallized from ethanol while compound 5b was
purified by preparative TLC using benzene:ethyl acetate (5:1) as an
eluting system.
(C]N), 162.40 (40 Ar-C), 177.61 (COOH). Anal. calcd. for C14H17NO4
(%): C, 63.87; H, 6.51; N, 5.32. Found: C, 63.73; H, 6.80; N, 5.17.
4.4. General method for synthesis of {[((E)-4-arylbut-3-en-2-
ylidene)amino]oxy}acetamides (6a–c), 2-{[((E)-4-arylbut-3-en-2-
ylidene)amino] oxy}propanamides (7a–c) (Scheme 1)
A mixture of compound 2,3a–c (0.05 mol) and ammonia solu-
tion (33%, 30 mL) in ethanol (50 mL) was stirred at room temper-
ature for 48 h. The solvent was evaporated under reduced pressure
and the residue was triturated with water, filtered, dried and
crystallized from ethanol.
4.3.1. {[((E)-4-(4-Chlorophenyl)but-3-en-2-ylidene)
amino]oxy}acetic acid (4b)
Yield, 45%; mp 109–110 ꢃC; IR (Nujol Mull) nmax/cmꢂ1 3031 (OH),
1709 (C]O), 1583 (C]N), 1480 (C]C). 1H NMR (CD3OD);
d 2.18
(s, 3H, CNCH3), 4.70 (s, 2H, OCH2COO), 6.84 (d, 1H, Ar-CH]CH), 7.05
(d, 1H, Ar-CH]CH), 7.40 (d, 2H, 20,60 Ar-H), 7.55 (d, 2H, 30,50 Ar-H),
4.4.1. {[((E)-4-Phenylbut-3-en-2-ylidene)amino]oxy}acetamide
(6a)
11.00 (s, 1H, COOH, D2O-exchang.). 13C NMR (CDCl3);
d 11.26
(CNCH3), 71.35 (OCH2COOH), 122.44 (Ar-CH]CH), 126.79 (30,50Ar-
C), 129.85 (20,60 Ar-C), 132.60 (10 Ar-C), 133.51 (40 Ar-C), 136.31 (Ar-
CH]CH),157.10 (C]N),171.92 (COOH). Anal. calcd. for C12H12ClNO3
(%): C, 56.81; H, 4.77; N, 5.52. Found: C, 56.64; H, 5.00; N, 5.36.
Yield, 40%; mp 128–129 ꢃC; IR (KBr) nmax/cmꢂ1 3463 (NH2), 1683
(C]O), 1606 (C]N), 1513 (C]C). 1H NMR (CD3OD);
d 2.22 (s, 3H,
CNCH3), 4.60 (s, 2H, OCH2CO), 6.86 (d, 1H, Ph-CH]CH), 7.10 (d, 1H,
Ph-CH]CH), 7.32–7.57 (m, 5H, Ar-H), 7.63 (s, 2H, NH2, D2O-
exchang.). Anal. calcd. for C12H14N2O2 (%): C, 66.04; H, 6.47; N,
12.84. Found: C, 66.24; H, 6.59; N, 12.53.
4.3.2. {[((E)-4-(4-Methoxyphenyl)but-3-en-2-ylidene)
amino]oxy}acetic acid (4c)
Yield, 55%; mp 124–126 ꢃC; IR (Nujol Mull) nmax/cmꢂ1 3038
(OH), 1718 (C]O), 1586 (C]N), 1486 (C]C). 1H NMR (CD3OD); 2.17
(s, 3H, CNCH3), 3.85 (s, 3H, OCH3), 4.65 (s, 2H, OCH2COOH), 6.71 (d,
1H, Ar-CH]CH), 6.95 (d, 2H, 30,50 Ar-H), 7.02 (d, 1H, Ar-CH]CH),
7.49 (d, 2H, 20,60 Ar-H), 11.00 (s, 1H, COOH, D2O-exchang.). MS m/z
(%); 251.00 (0.69, Mþ þ 2), 250.00 (5.08, Mþ þ 1), 249.00 (35.62,
Mþ), 248.00 (37.47), 174.00 (100.00), 160.00 (13.54), 144.00 (9.30),
131.00 (35.33), 130.00 (10.73), 107.00 (2.08). Anal. calcd. for
C13H15NO4 (%): C, 62.64; H, 6.07; N, 5.62. Found: C, 62.33; H, 6.02; N,
5.33.
4.4.2. {[((E)-4-(4-Chlorophenyl)but-3-en-2-ylidene)
amino]oxy}acetamide (6b)
Yield, 42%; mp 131–133 ꢃC; IR (KBr) nmax/cmꢂ1 3461 (NH2), 1682
(C]O), 1603 (C]N), 1512 (C]C). 1H NMR (CDCl3);
d 2.14 (s, 3H,
CNCH3), 4.48 (s, 2H, OCH2CO), 6.89 (d,1H, Ar-CH]CH), 7.11 (d,1H, Ar-
CH]CH), 7.44 (d, 2H, 20,60 Ar-H), 7.66 (d, 2H, 30,50 Ar-H), 7.68 (s, 2H,
NH2, D2O-exchang.).13C NMR (CDCl3);
d 10.34 (CNCH3), 73.47
(OCH2CO),126.77 (Ar-CH]CH),129.21 (30,50Ar-C),129.60 (20,60 Ar-C),
133.39 (10Ar-C),133.76 (40 Ar-C),157.56 (C]N),171.87 (CONH2). Anal.
calcd. for C12H13ClN2O2 (%): C, 57.04; H, 5.19; N,11.09. Found: C, 57.31;
H, 4.89; N, 11.30.
4.3.3. 2-{[((E)-4-Phenylbut-3-en-2-ylidene)amino]oxy}propanoic
acid (5a)
4.4.3. {[((E)-4-(4-Methoxyphenyl)but-3-en-2-ylidene)
amino]oxy}acetamide (6c)
Yield, 35%; mp 110–111 ꢃC; IR (Nujol Mull) nmax/cmꢂ1 3039 (OH),
1720 (C]O), 1587 (C]N), 1486 (C]C). 1H NMR (CDCl3);
d
1.53 (d,
Yield, 43%; mp 160–162 ꢃC; IR (KBr) nmax/cmꢂ1 3460 (NH2), 1684
3H, CHCH3), 2.17 (s, 3H, CNCH3), 4.73 (q,1H, CHCH3), 6.82 (d,1H, Ph-
(C]O), 1600 (C]N), 1510 (C]C). 1H NMR (CD3OD);
d 2.20 (s, 3H,
CH]CH), 7.05 (d, 1H, Ph-CH]CH), 7.30–7.54 (m, 5H, Ar-H), 12.86 (s,
CNCH3), 3.85 (s, 3H, OCH3), 4.58 (s, 2H, OCH2CO), 6.72 (d, 1H, Ar-
CH]CH), 6.96 (d, 2H, 30,50 Ar-H), 7.04 (d, 1H, Ar-CH]CH), 7.49
(d, 2H, 20,60 Ar-H), 7.62 (s, 2H, NH2, D2O-exchang.). Anal. calcd. for
C13H16N2O3 (%): C, 62.89; H, 6.50; N, 11.28. Found: C, 62.78; H, 6.67;
N, 10.92.
1H, COOH, D2O-exchang.). 13C NMR (CDCl3);
d 11.39 (CN–CH3), 18.11
(CHCH3), 79.49 (CHCH3), 127.02 (Ar-CH]CH), 128.78 (40 Ar-C),
130.42 (20,60 Ar-C), 130.67 (30,50 Ar-C), 136.13 (10 Ar-C), 138.58 (Ar-
CH]CH), 159.20 (C]N), 177.60 (COOH). Anal. calcd. for C13H15NO3
(%): C, 66.94; H, 6.48; N, 6.00. Found: C, 66.78; H, 6.65; N, 5.85.
4.4.4. 2-{[((E)-4-Phenylbut-3-en-2-ylidene)
amino]oxy}propanamide (7a)
4.3.4. 2-{[((E)-4-(4-Chlorophenyl)but-3-en-2-ylidene)
amino]oxy}propanoic acid (5b)
Yield, 47%; mp 104–107 ꢃC; IR (KBr) nmax/cmꢂ1 3322 (NH2), 1668
Yield, 35%; oil; IR (Nujol Mull) nmax/cmꢂ1 3042 (OH), 1723
(C]O), 1604 (C]N), 1511 (C]C). 1H NMR (CDCl3);
d 1.55 (d, 3H,
CHCH3), 2.19 (s, 3H, CNCH3), 4.64 (q, 1H, CHCH3), 6.83 (d, 1H, Ph-
(C]O), 1589 (C]N), 1488 (C]C). 1H NMR (DMSO-d6);
d
1.55 (d, 3H,
CHCH3), 2.08 (s, 3H, CNCH3), 4.64 (q, 1H, CHCH3), 6.82 (d, 1H, Ar-
CH]CH), 7.10 (d, 1H, Ar-CH]CH), 7.40 (d, 2H, 20,60 Ar-H), 7.62
(d, 2H, 30,50 Ar-H), 12.85 (s, 1H, COOH, D2O-exchang.).
Anal. calcd. for C13H14ClNO3: C, 58.32; H, 5.27; N, 5.23. Found: C,
58.12; H, 5.40; N, 5.14.
CH]CH), 7.07 (d, 1H, Ph-CH]CH), 7.19 (s, 2H, NH2, D2O-exchang.),
7.40–7.65 (m, 5H, Ar-H).13C NMR (CDCl3);
d 10.96 (CN–CH3), 18.81
(CHCH3), 79.34 (CHCH3), 125.71 (Ph-CH]CH), 127.37 (40 Ar-C),
128.90 (20,60 Ar-C), 129.23 (30,50 Ar-C), 134.09 (10 Ar-C), 136.57 (Ph-
CH]CH), 156.77 (C]N), 174.40 (CONH2). Anal. calcd. for
C13H16N2O2 (%): C, 67.22; H, 6.94; N, 12.06. Found: C, 67.09; H, 7.10;
N, 11.95.
4.3.5. 2-{[((E)-4-(4-Methoxyphenyl)but-3-en-2-ylidene)
amino]oxy}propanoic acid (5c)
Yield, 40%; mp 55–58 ꢃC; IR (Nujol Mull) nmax/cmꢂ1 3040 (OH),
4.4.5. 2-{[((E)-4-(4-Chlorophenyl)but-3-en-2-ylidene)
amino]oxy}propanamide (7b)
1719 (C]O), 1585 (C]N), 1485 (C]C). 1H NMR (CDCl3);
d 1.51 (d,
3H, CHCH3), 2.15 (s, 3H, CNCH3), 3.84 (s, 3H, OCH3), 4.71 (q, 1H,
CHCH3), 6.68 (d,1H, Ar-CH]CH), 6.93 (d, 2H, 30,50 Ar-H), 6.98 (d,1H,
Ar-CH]CH), 7.46 (d, 2H, 20,60 Ar-H), 12.83 (s, 1H, COOH, D2O-
Yield, 35%; mp 78–80 ꢃC; IR (KBr) nmax/cmꢂ1 3320 (NH2), 1667
(C]O), 1601 (C]N), 1510 (C]C). 1H NMR (CDCl3);
d 1.51 (d, 3H,
CHCH3), 2.10 (s, 3H, CNCH3), 4.61 (q, 1H, CHCH3), 6.84 (d, 1H, Ar-
exchang.). 13C NMR (CDCl3);
d
11.43 (CN–CH3), 17.66 (CHCH3), 56.67
CH]CH), 7.06 (d, 1H, Ar-CH]CH), 7.21 (s, 2H, NH2, D2O-exchang.),
(OCH3), 79.43 (CHCH3), 116.09 (30,50 Ar-C), 124.73 (Ar-CH]CH),
7.42 (d, 2H, 20,60 Ar-H), 7.63(d, 2H, 30,50 Ar-H).13CNMR(CDCl3);
d
10.95
130.21 (10 Ar-C), 130.96 (20,60 Ar-C), 135.87 (Ar-CH]CH), 159.49
(CN–CH3),17.80 (CHCH3), 79.37 (CHCH3),126.58 (Ar-CH]CH),129.08

M.I. El-Gamal et al. / European Journal of Medicinal Chemistry 45 (2010) 1403–1414
1411
(30,50 Ar-C),132.78 (20,60 Ar-C),133.27 (10 Ar-C),135.57 (40 Ar-C),137.90
(Ar-CH]CH), 156.69 (C]N), 174.34 (CONH2). Anal. calcd. for
C13H15ClN2O2 (%): C, 58.54; H, 5.67; N,10.50. Found: C, 58.42; H, 5.90;
N, 10.68.
CH(CH3)2), 1.35 (d, 3H, CHCH3), 2.12 (s, 3H, CNCH3), 3.80–3.94 (m,
1H, CH(CH3)2), 4.53 (q, 1H, CHCH3), 6.80 (d, 1H, Ph-CH]CH), 7.08
(d, 1H, Ph-CH]CH), 7.27–7.61 (m, 6H, Ar-H and NH (D2O-
exchang.)). Anal. calcd. for C16H22N2O2 (%): C, 70.04; H, 8.08; N,
10.21. Found: C, 69.84; H, 8.35; N, 10.12.
4.4.6. 2-{[((E)-4-(4-Methoxyphenyl)but-3-en-2-ylidene)
amino]oxy}propanamide (7c)
4.5.5. N-(Prop-2-yl)-2-{[((E)-4-(4-chlorophenyl)but-3-en-2-ylidene)
amino]oxy}propanamide (9b)
Yield, 42%; mp 100–102 ꢃC; IR (KBr) nmax/cmꢂ1 3323 (NH2), 1669
(C]O), 1605 (C]N), 1514 (C]C). 1H NMR (CDCl3);
d
1.50 (d, 3H,
Yield, 40%; mp 75–78 ꢃC; IR (KBr) nmax/cmꢂ1 3284 (NH), 1656
CHCH3), 2.17 (s, 3H, CNCH3), 3.83 (s, 3H, OCH3), 4.61 (q, 1H, CHCH3),
6.68 (d, 1H, Ar-CH]CH), 6.72 (d, 2H, 30,50 Ar-H), 6.93 (d, 1H, Ar-
CH]CH), 7.20 (s, 2H, NH2, D2O-exchang.), 7.47 (d, 2H, 20,60 Ar-H).
(C]O), 1550 (C]N), 1494 (C]C). 1H NMR (DMSO-d6);
d 1.11 (d, 6H,
CH(CH3)2), 1.36 (d, 3H, CHCH3), 2.10 (s, 3H, CNCH3), 3.83–3.97
(m, 1H, CH(CH3)2), 4.54 (q, 1H, CHCH3), 6.83 (d, 1H, Ar-CH]CH),
7.08 (d, 1H, Ar-CH]CH), 7.29 (d, 2H, 20,60 Ar-H), 7.56 (d, 2H, 30,50 Ar-
H), 8.16 (s, 1H, NH, D2O-exchang.). Anal. calcd. for C16H21ClN2O2 (%):
C, 62.23; H, 6.85; N, 9.07. Found: C, 62.40; H, 6.69; N, 9.18.
13C NMR (CDCl3);
d 11.48 (CN–CH3), 18.72 (CHCH3), 56.65 (OCH3),
81.23 (CHCH3), 116.09 (30,50 Ar-C), 124.63 (Ar-CH]CH), 130.21 (10
Ar-C), 131.22 (20,60 Ar-C), 135.99 (Ar-CH]CH), 159.88 (C]N), 162.41
(40 Ar-C), 179.55 (CONH2). Anal. calcd. for C14H18N2O3 (%): C, 64.10;
H, 6.92; N, 10.68. Found: C, 63.87; H, 7.21; N, 10.56.
4.5.6. N-(Prop-2-yl)-2-{[((E)-4-(4-methoxyphenyl)but-3-en-2-
ylidene)amino]oxy}propanamide (9c)
4.5. General method for synthesis of N-(prop-2-yl)-{[((E)-4-
arylbut-3-en-2-ylidene)amino]oxy}acetamides (8a–c) and N-(prop-
2-yl)-2-{[((E)-4-arylbut-3-en-2-ylidene)amino]oxy}propanamides
(9a–c) (Scheme 1)
Yield, 40%; mp 157–158 ꢃC; IR (KBr) nmax/cmꢂ1 3283 (NH), 1655
(C]O), 1549 (C]N), 1493 (C]C). 1H NMR (CDCl3);
d 1.13 (d, 6H,
CH(CH3)2), 1.42 (d, 3H, CHCH3), 2.13 (s, 3H, CNCH3), 3.79 (s, 3H,
OCH3), 3.96–4.01 (m, 1H, CH(CH3)2), 4.62 (q, 1H, CHCH3), 6.67
(d, 1H, Ar-CH]CH), 6.90 (d, 2H, 30,50 Ar-H), 6.96 (d, 1H, Ar-CH]CH),
7.43 (d, 2H, 20,60 Ar-H), 8.14 (s, 1H, NH, D2O-exchang.). 13C NMR
A mixture of compound 2,3a–c (0.05 mol) and isopropylamine
(30 mL) in ethanol (50 mL) was stirred at room temperature for
48 h. The reaction mixture was evaporated under reduced pres-
sure; the residue was triturated with water, filtered, dried and
crystallized from ethanol.
(CDCl3);
d 11.47 (CN–CH3), 18.61 (CHCH3), 23.32 (CH(CH3)2), 43.26
(CH(CH3)2), 56.64 (OCH3), 81.27 (CHCH3), 116.09 (30,50 Ar-C), 124.65
(Ar-CH]CH), 130.20 (10 Ar-C), 131.25 (20,60 Ar-C), 135.96 (Ar-
CH]CH), 159.88 (C]N), 162.41 (40 Ar-C), 179.54 (CONH). Anal.
calcd. for C17H24N2O3 (%): C, 67.08; H, 7.95; N, 9.20. Found: C, 66.88;
H, 8.09; N, 9.08.
4.5.1. N-(Prop-2-yl)-{[((E)-4-phenylbut-3-en-2-ylidene)
amino]oxy}acetamide (8a)
Yield, 75%; mp 102–104 ꢃC; IR (KBr) nmax/cmꢂ1 3290 (NH), 1651
4.6. General method for synthesis of {[((E)-4-arylbut-3-en-2-
ylidene)amino]oxy}acetohydrazides (10a–c) and 2-{[((E)-4-
arylbut-3-en-2-ylidene)amino]oxy}propanoic acid hydrazides
(11a–c) (Scheme 1)
(C]O), 1550 (C]N), 1490 (C]C). 1H NMR (CD3OD);
d 1.22 (d, 6H,
CH(CH3)2), 2.22 (s, 3H, CNCH3), 4.09–4.13 (m,1H, CH(CH3)2), 4.57 (s, 2H,
OCH2CO), 6.85 (d, 1H, Ph-CH]CH), 7.09 (d,1H, Ph-CH]CH), 7.33–7.57
(m, 6H, Ar-H and NH (D2O-exchang.)). Anal. calcd. for C15H20N2O2 (%):
C, 69.20; H, 7.74; N, 10.76. Found: C, 69.33; H, 7.49; N, 10.86.
A mixture of compound 2,3a–c (0.05 mol) and hydrazine
hydrate (99%, 0.10 mol) in absolute ethanol (20 mL) was heated
under reflux for 24 h. The solvent was evaporated under reduced
pressure, the residue was triturated with water, filtered, dried and
crystallized from ethanol.
4.5.2. N-(Prop-2-yl)-{[((E)-4-(4-chlorophenyl)but-3-en-2-ylidene)
amino]oxy}acetamide (8b)
Yield, 50%; mp 79–80 ꢃC; IR (KBr) nmax/cmꢂ1 3289 (NH), 1645
(C]O), 1552 (C]N), 1488 (C]C). 1H NMR (DMSO-d6);
d 1.22 (d, 6H,
CH(CH3)2), 2.11 (s, 3H, CNCH3), 4.37–4.41 (m,1H, CH(CH3)2), 4.46 (s, 2H,
OCH2CO), 6.85 (d,1H, Ar-CH]CH), 7.09 (d,1H, Ar-CH]CH), 7.42 (d, 2H,
20,60 Ar-H), 7.47 (d, 2H, 30,50 Ar-H), 7.64 (s, 1H, NH, D2O-exchang.). 13C
4.6.1. {[((E)-4-Phenylbut-3-en-2-ylidene)
amino]oxy}acetohydrazide (10a)
Yield, 30%; mp 125–126 ꢃC; IR (KBr) nmax/cmꢂ1 3373 (NH2), 3327
NMR (DMSO-d6);
d
10.97 (CNCH3), 22.74 (CH(CH3)2), 40.40 (CH(CH3)2),
(NH),1646 (C]O),1606 (C]N),1511 (C]C).1H NMR (CD3OD);
d 2.20
73.16 (OCH2CO), 124.41 (40 Ar-C), 128.60 (Ar-CH]CH), 129.22 (30,50 Ar-
C), 133.33 (20,60 Ar-C), 134.13 (10 Ar-C), 135.88 (Ar-CH]CH), 156.97
(C]N), 168.06 (CONH). Anal. calcd. for C15H19ClN2O2 (%): C, 61.12; H,
6.50; N, 9.50. Found: C, 60.98; H, 6.78; N, 9.35.
(s, 3H, CNCH3), 3.36 (s, 2H, NH2, D2O-exchang.), 4.60 (s, 2H, OCH2CO),
6.83 (d, 1H, Ph-CH]CH), 7.09 (d, 1H, Ph-CH]CH), 7.24–7.56 (m, 6H,
Ar-H and NH (D2O-exchang.)). Anal. calcd. for C12H15N3O2 (%): C,
61.79; H, 6.48; N, 18.01. Found: C, 61.87; H, 6.78; N, 17.74.
4.5.3. N-(Prop-2-yl)-{[((E)-4-(4-methoxyphenyl)but-3-en-2-ylidene)
amino]oxy}acetamide (8c)
4.6.2. {[((E)-4-(4-Chlorophenyl)but-3-en-2-ylidene)
amino]oxy}acetohydrazide (10b)
Yield, 70%; mp 128–130 ꢃC; IR (KBr) nmax/cmꢂ1 3292 (NH), 1652
Yield, 30%; mp 145–147 ꢃC; IR (KBr) nmax/cmꢂ1 3370 (NH2), 3325
(C]O), 1551 (C]N), 1493 (C]C). 1H NMR (CD3OD);
d 1.22 (d, 6H,
(NH), 1646 (C]O), 1604 (C]N), 1510 (C]C). 1H NMR (CD3OD);
CH(CH3)2), 2.20 (s, 3H, CNCH3), 3.85 (s, 3H, OCH3), 4.10–4.14 (m, 1H,
CH(CH3)2), 4.55 (s, 2H, OCH2CO), 6.71 (d, 1H, Ar-CH]CH), 6.95 (d,
2H, 30,50 Ar-H), 7.04 (d, 1H, Ar-CH]CH), 7.50 (d, 2H, 20,60 Ar-H), 7.64
(s, 1H, NH, D2O-exchang.). Anal. calcd. for C16H22N2O3 (%): C, 66.18;
H, 7.64; N, 9.65. Found: C, 65.94; H, 7.89; N, 9.54.
d 2.19 (s, 3H, CNCH3), 3.75 (s, 2H, NH2, D2O-exchang.), 4.64 (s, 2H,
OCH2CO), 6.83 (d, 1H, Ar-CH]CH), 7.07 (d, 1H, Ar-CH]CH), 7.35
(s, 1H, NH, D2O-exchang.), 7.40 (d, 2H, 20,60 Ar-H), 7.55 (d, 2H, 30,50
Ar-H). Anal. calcd. for C12H14ClN3O2 (%): C, 53.84; H, 5.27; N, 15.70.
Found: C, 53.61; H, 5.52; N, 15.58.
4.5.4. N-(Prop-2-yl)-2-{[((E)-4-phenylbut-3-en-2-
ylidene)amino]oxy}propanamide (9a)
4.6.3. {[((E)-4-(4-Methoxyphenyl)but-3-en-2-ylidene)
amino]oxy}acetohydrazide (10c)
Yield, 45%; mp 111–112 ꢃC; IR (KBr) nmax/cmꢂ1 3285 (NH), 1657
Yield, 30%; mp 148–150 ꢃC; IR (KBr) nmax/cmꢂ1 3372 (NH2), 3326
(NH), 1644 (C]O), 1606 (C]N), 1511 (C]C). 1H NMR (CD3OD);
(C]O), 1551 (C]N), 1496 (C]C). 1H NMR (DMSO-d6);
d 1.08 (d, 6H,

1412
M.I. El-Gamal et al. / European Journal of Medicinal Chemistry 45 (2010) 1403–1414
d
2.19 (s, 3H, CNCH3), 3.80 (s, 2H, NH2, D2O-exchang.), 3.85 (s, 3H,
(400 Ar-C), 130.51 (20,60 Ar-C), 131.06 (30,50 Ar-C), 131.18 (300,500 Ar-C),
135.81 (10 Ar-C), 137.80 (Ph-CH]CH), 138.85 (100 Ar-C), 157.43
(C]N), 170.30 (CONH). Anal. calcd. for C18H18N2O2 (%): C, 73.45; H,
6.16; N, 9.52. Found: C, 73.29; H, 6.35; N, 9.43.
OCH3), 4.59 (s, 2H, OCH2CO), 6.70 (d, 1H, Ar-CH]CH), 6.86 (d, 2H,
30,50 Ar-H), 6.94 (s, 1H, NH, D2O-exchang.), 7.03 (d, 1H, Ar-CH]CH),
7.49 (d, 2H, 20,60 Ar-H). Anal. calcd. for C13H17N3O3 (%): C, 59.30; H,
6.51; N, 15.96. Found: C, 59.40; H, 6.68; N, 15.72.
4.7.2. N-(4-Chlorophenyl)-{[((E)-4-phenylbut-3-en-2-
ylidene)amino]oxy}acetamide (13b)
4.6.4. 2-{[((E)-4-Phenylbut-3-en-2-ylidene)amino]oxy}propanoic
acid hydrazide (11a)
Yield, 35% (a), 50% (b); mp 107–109 ꢃC; IR (KBr) nmax/cmꢂ1 3395
Yield, 30%; mp 125–126 ꢃC; IR (KBr) nmax/cmꢂ1 3401 (NH2), 3310
(NH), 1664 (C]O), 1600 (C]N), 1511 (C]C). 1H NMR (DMSO-d6);
d 2.11 (s, 3H, CNCH3), 4.84 (s, 2H, OCH2CO), 6.56 (d,1H, Ph-CH]CH),
(NH),1652 (C]O),1585 (C]N), 1530 (C]C). 1H NMR (CDCl3);
d
1.49
(d, 3H, CHCH3), 2.18 (s, 3H, CNCH3), 4.22 (s, 2H, NH2, D2O-exchang.),
4.67 (q, 1H, CHCH3), 6.81 (d, 1H, Ph-CH]CH), 7.06 (d, 1H, Ph-
CH]CH), 7.31–7.53 (m, 5H, Ar-H), 9.08 (s, 1H, NH, D2O-exchang.).
7.01 (d, 1H, Ph-CH]CH), 7.14–7.63 (m, 9H, Ar-H), 10.03 (s, 1H, NH,
D2O-exchang.). Anal. calcd. for C18H17ClN2O2 (%): C, 65.75; H, 5.21;
N, 8.52. Found: C, 65.52; H, 5.39; N, 8.64.
13C NMR (CDCl3);
d 11.47 (CN–CH3), 18.56 (CHCH3), 80.59 (CHCH3),
126.94 (Ph-CH]CH), 128.78 (40 Ar-C), 130.48 (20,60 Ar-C), 130.69
(30,50 Ar-C), 136.28 (10 Ar-C), 138.51 (Ph-CH]CH), 159.65 (C]N),
175.11 (CONHNH2). Anal. calcd. for C13H17N3O2 (%): C, 63.14; H, 6.93;
N, 16.99. Found: C, 63.03; H, 7.21; N, 16.86.
4.7.3. N-(4-Methoxyphenyl)-{[((E)-4-phenylbut-3-en-2-ylidene)
amino]oxy}acetamide (13c)
Yield, 30% (a), 40% (b); mp 100–103 ꢃC; IR (KBr) nmax/cmꢂ1 3392
(NH), 1653 (C]O), 1601 (C]N), 1512 (C]C). 1H NMR (DMSO-d6);
d
2.11 (s, 3H, CNCH3), 3.73 (s, 3H, OCH3), 4.80 (s, 2H, OCH2CO), 6.59
4.6.5. 2-{[((E)-4-(4-Chlorophenyl)but-3-en-2-ylidene)
amino]oxy}propanoic acid hydrazide (11b)
(d, 1H, Ph-CH]CH), 7.05 (d, 1H, Ph-CH]CH), 7.14–7.62 (m, 9H, Ar-
H), 10.01 (s, 1H, NH, D2O-exchang.). Anal. calcd. for C19H20N2O3 (%):
C, 70.35; H, 6.21; N, 8.64. Found: C, 70.52; H, 6.09; N, 8.84.
Yield, 25%; mp 133–134 ꢃC; IR (KBr) nmax/cmꢂ1 3399 (NH2), 3309
(NH), 1652 (C]O), 1583 (C]N),1529 (C]C). 1H NMR (CDCl3);
d 1.36
(d, 3H, CHCH3), 2.11 (s, 3H, CNCH3), 4.21 (s, 2H, NH2, D2O-exchang.),
4.49 (q, 1H, CHCH3), 6.85 (d, 1H, Ar-CH]CH), 7.10 (d, 1H, Ar-
CH]CH), 7.46 (d, 2H, 20,60 Ar-H), 7.67 (d, 2H, 30,50 Ar-H), 9.06 (s, 1H,
NH, D2O-exchang.). Anal. calcd. for C13H16ClN3O2 (%): C, 55.42; H,
5.72; N, 14.91. Found: C, 55.62; H, 5.56; N, 14.83.
4.7.4. N-Phenyl-{[((E)-4-(4-chlorophenyl)but-3-en-2-ylidene)
amino]oxy}acetamide (14a)
Yield, 45% (a), 60% (b); mp 137–138 ꢃC; IR (KBr) nmax/cmꢂ1 3399
(NH), 1650 (C]O), 1600 (C]N), 1509 (C]C). 1H NMR (DMSO-d6);
d
2.11 (s, 3H, CNCH3), 4.85 (s, 2H, OCH2CO), 6.57 (d, 1H, Ar-CH]CH),
7.03 (d, 1H, Ar-CH]CH), 7.14–7.64 (m, 9H, Ar-H), 10.05 (s, 1H, NH,
D2O-exchang.). 13C NMR (CDCl3);
11.29 (CNCH3), 71.34 (OCH2CO),
4.6.6. 2-{[((E)-4-(4-Methoxyphenyl)but-3-en-2-ylidene)
amino]oxy}propanoic acid hydrazide (11c)
d
122.76 (200, 600 Ar-C), 123.73 (Ar-CH]CH), 128.71 (40 Ar-C), 130.13
(400 Ar-C), 130.51 (20,60 Ar-C), 131.14 (30,50 Ar-C), 132.71 (300,500 Ar-C),
135.81(10 Ar-C), 137.80 (Ar-CH]CH), 138.94 (100 Ar-C), 157.08
(C]N), 171.87 (CONH).Anal. calcd. for C18H17ClN2O2 (%): C, 65.75; H,
5.21; N, 8.52. Found: C, 65.52; H, 5.39; N, 8.64.
Yield, 30%; mp 140–141 ꢃC; IR (KBr) nmax/cmꢂ1 3395 (NH2), 3305
(NH),1651 (C]O),1580 (C]N),1525 (C]C). 1H NMR (CDCl3);
d 1.48 (d,
3H, CHCH3), 2.16 (s, 3H, CNCH3), 3.83 (s, 3H, OCH3), 4.20 (s, 2H, NH2,
D2O-exchang.),4.64(q,1H,CHCH3), 6.67 (d,1H, Ar-CH]CH), 6.85 (d, 2H,
30,50 Ar-H), 6.97 (d, 1H, Ar-CH]CH), 7.46 (d, 2H, 20,60 Ar-H), 9.06 (s, 1H,
NH, D2O-exchang.). 13C NMR (CDCl3);
d
11.44 (CN–CH3), 15.52 (CHCH3),
4.7.5. N-(4-Chlorophenyl)-{[((E)-4-(4-chlorophenyl)but-3-en-2-
ylidene)amino]oxy}acetamide (14b)
56.52 (OCH3), 80.50 (CHCH3), 115.66 (30,50 Ar-C), 124.66 (Ar-CH]CH),
130.18 (10 Ar-C), 131.22 (20,60 Ar-C), 135.96 (Ar-CH]CH), 159.84 (C]N),
161.50 (40 Ar-C), 175.19 (CONHNH2). Anal. calcd. for C14H19N3O3 (%): C,
60.63; H, 6.91; N, 15.15. Found: C, 60.46; H, 6.65; N, 15.32.
Yield, 35% (a), 45% (b); mp 100–102 ꢃC; IR (KBr) nmax/cmꢂ1 3420
(NH), 1649 (C]O), 1601 (C]N), 1505 (C]C). 1H NMR (DMSO-d6);
d
2.11 (s, 3H, CNCH3), 4.83 (s, 2H, OCH2CO), 6.57 (d, 1H, Ar-CH]CH),
7.00 (d, 1H, Ar-CH]CH), 7.14–7.63 (m, 8H, Ar-H), 10.04 (s, 1H, NH,
D2O-exchang.).
4.7. General method for synthesis of N-aryl-{[((E)-4-arylbut-3-en-
2-ylidene)amino]oxy}acetamides (13–15a,b,c) (Scheme 2)
Anal. calcd. for C18H16Cl2N2O2 (%): C, 59.52; H, 4.44; N, 7.71.
Found: C, 59.40; H, 4.68; N, 7.62.
A mixture of the oxime derivative 1a–c (0.05 mol) and sodium
methoxide (2.70 g, 0.05 mol) in anhydrous methanol (50 mL) was
heated under reflux for 2 h. The solvent was evaporated under
reduced pressure and the residual oximate salt was dissolved in dry
DMF (5 mL). A solution of the appropriate 2-chloro-N-arylaceta-
mide derivative (12a–c) (0.05 mol) in dry DMF (10 mL) was added
to the previous oximate sodium salt solution and the reaction
mixture was heated at 80 ꢃC for 48 h. After cooling, the reaction
mixture was poured over crushed ice (10 g) and stirred for 5 min.
The separated solid was filtered, washed with water, dried and
crystallized from ethanol.
4.7.6. N-(4-Methoxyphenyl)-{[((E)-4-(4-chlorophenyl)but-3-en-2-
ylidene)amino]oxy}acetamide (14c)
Yield, 30% (a), 50% (b); mp 140–142 ꢃC; IR (KBr) nmax/cmꢂ1
3422 (NH), 1651 (C]O), 1602 (C]N), 1508 (C]C). 1H NMR
(DMSO-d6);
d 2.09 (s, 3H, CNCH3), 3.75 (s, 3H, OCH3), 4.78 (s, 2H,
OCH2CO), 6.94 (d, 1H, Ar-CH]CH), 7.30 (d, 1H, Ar-CH]CH), 7.49–
7.78 (m, 8H, Ar-H), 10.01 (s, 1H, NH, D2O-exchang.). Anal. calcd.
for C19H19ClN2O3 (%): C, 63.60; H, 5.34; N, 7.81. Found: C, 63.41;
H, 5.60; N, 7.64.
4.7.7. N-Phenyl-{[((E)-4-(4-methoxyphenyl)but-3-en-2-ylidene)
amino]oxy}acetamide (15a)
4.7.1. N-Phenyl-{[((E)-4-phenylbut-3-en-2-ylidene)
amino]oxy}acetamide (13a)
Yield, 45% (a), 55% (b); mp 107–108 ꢃC; IR (KBr) nmax/cmꢂ1
Yield, 30% (a), 45% (b); mp 97–99 ꢃC; IR (KBr) nmax/cmꢂ1 3422
3400 (NH), 1640 (C]O), 1605 (C]N), 1501 (C]C). 1H NMR
(NH), 1653 (C]O), 1603 (C]N), 1511 (C]C). 1H NMR (DMSO-d6);
(DMSO-d6);
d 2.11 (s, 3H, CNCH3), 3.73 (s, 3H, OCH3), 4.80 (s, 2H,
d
2.10 (s, 3H, CNCH3), 4.85 (s, 2H, OCH2CO), 6.58 (d,1H, Ph-CH]CH),
7.02 (d, 1H, Ph-CH]CH), 7.15–7.62 (m, 10H, Ar-H), 10.02 (s, 1H, NH,
D2O-exchang.). 13C NMR (CDCl3);
10.32 (CNCH3), 71.34 (OCH2CO),
122.14 (200, 600 Ar-C), 124.34 (Ph-CH]CH), 128.49 (40 Ar-C), 130.13
OCH2CO), 6.59 (d, 1H, Ar-CH]CH), 6.83 (d, 1H, Ar-CH]CH), 7.14–
7.64 (m, 9H, Ar-H), 10.01 (s, 1H, NH, D2O-exchang.).Anal. calcd. for
C19H20N2O3 (%): C, 70.35; H, 6.21; N, 8.64. Found: C, 70.12; H,
6.40; N, 8.34.
d

M.I. El-Gamal et al. / European Journal of Medicinal Chemistry 45 (2010) 1403–1414
1413
4.7.8. N-(4-Chlorophenyl)-{[((E)-4-(4-methoxyphenyl)but-3-en-2-
5.4. Potential ulcerogenicity
ylidene)amino]oxy}acetamide (15b)
Yield, 45% (a), 65% (b); mp 137–139 ꢃC; IR (KBr) nmax/cmꢂ1 3421
Ulcerogenic liability was determined following the method of
Adami et al. [32]. The rats were divided into 4 groups, 5 rats each,
the tested compounds (5b and 7a) and diclofenac sodium were
given orally to the rats in equimolar doses (equivalent to
0.169 M/kg). The doses were repeated daily for 5 days. The animals
were sacrificed 10 h after the last treatment, by over-dose of ether.
The stomach was removed, rinsed with saline, opened along the
greater curvature, studied with hand lens (ꢄ10 magnification).
The number of ulcers and the total sum of lengths of ulcers for
each animal were recorded and the mean was calculated and taken
as ulcer index.
(NH), 1649 (C]O), 1600 (C]N), 1500 (C]C). 1H NMR (DMSO-d6);
d
2.09 (s, 3H, CNCH3), 3.73 (s, 3H, OCH3), 4.81 (s, 2H, OCH2CO), 6.59
(d, 1H, Ar-CH]CH), 6.97 (d, 1H, Ar-CH]CH), 7.00–7.54 (m, 8H, Ar-
H), 10.05 (s, 1H, NH, D2O-exchang.). Anal. calcd. for C19H19ClN2O3
(%): C, 63.60; H, 5.34; N, 7.81. Found: C, 63.43; H, 5.63; N, 7.70.
4.7.9. N-(4-Methoxyphenyl)-{[((E)-4-(4-methoxyphenyl)but-3-en-
2-ylidene)amino]oxy}acetamide (15c)
Yield, 30% (a), 45% (b); mp 124–125 ꢃC; IR (KBr) nmax/cmꢂ1 3421
(NH), 1652 (C]O), 1600 (C]N), 1511 (C]C). 1H NMR (DMSO-d6);
d
2.09 (s, 3H, CNCH3), 3.79 (s, 6H, 2ꢃ CH3), 4.81 (s, 2H, OCH2CO), 6.59
(d, 1H, Ar-CH]CH), 6.97 (d, 1H, Ar-CH]CH), 7.01–7.54 (m, 8H, Ar-
H), 10.06 (s, 1H, NH, D2O-exchang.). Anal. calcd. for C20H22N2O4 (%):
C, 67.78; H, 6.26; N, 7.90. Found: C, 67.54; H, 6.50; N, 7.74.
5.5. Determination of acute toxicity
Twelve groups of wister rats each comprised of 5 animals were
used in this study (4 groups for each compound). Compounds 5b
and 7a were given intraperitoneally at doses of 250, 500, 750 and
1000 mg/kg to rat groups while diclofenac sodium was given at
doses of 100, 150, 200 and 300 mg/kg. The percentage mortality in
each group was determined 24 h after administration. Calculation
of LD50 and 95% confidence limits was done according to the
method of Litchfield and Wilcoxon [33].
5. Pharmacology
5.1. Materials and animals
Wister rats weighing in the range 100–120 g and Swiss albino
mice of either sex weighing 20–25 g were purchased from local
source and kept at room temperature (22 ꢁ 2 ꢃC) in a light-
controlled room with an alternating 12 h light/dark cycle. Animals
were allowed to become acclimatized to laboratory conditions
before experimentation and allowed free access to standard food
and water. The tested compounds were prepared as suspension in
2% gum acacia in sterile distilled water. Diclofenac sodium was used
as a standard drug, dissolved in sterile distilled water. The positive
control group animals received the reference drug while the
negative control received only the vehicle.
6. Molecular modeling methods
6.1. Conformational search
Initial structures for the molecules 5b and 7a were constructed
using the HyperChem program version 5.11. The MMþ (calculations
in vacuo, bond dipole option for electrostatics, Polake–Ribiere
algorithm, and RMS gradient of 0.01 kcal/mol) conformational
searching in torsional space was performed using the multicon-
former method [34]. Energy minima for compounds 5b and 7a
were determined by a semi-empirical method AM1 (as imple-
mented in HyperChem 5.11). The conformations thus obtained
were confirmed as minima by vibrational analysis.
5.2. Anti-inflammatory activity
The anti-inflammatory activity was evaluated using in vivo
carrageenin-induced rat paw oedema model [30] which is consid-
ered the most conventional one for acute inflammation. The rats
were divided into 41 groups, 5 rats each, and were injected intra-
peritoneally with equimolar doses (equivalent to 0.169 M/kg) of the
tested compounds and reference drug (diclofenac sodium). One
hour after drug administration, rats were subcutaneously injected
with 0.05 mL carrageenin (1% solution in saline prepared 24 h before
use) into the subplantar tissue of the right hind paw. The left hind
paw of each rat received a subplantar injection of equal volume of
normal saline. Three hours after carrageenin injection, rats were
killed by cervical dislocation, then the right and the left hind paws of
each rat were cut at the tibiotarsic articulation and weighed. The
difference in weight between right and left paws was recorded for
each rat. The percentage increase in weight of the carrageenin-
injected paw over the other paw was calculated and percentage
reduction of oedema from the control group was used as a measure
of the activity. Compounds 5b and 7a as well as diclofenac sodium
6.2. Docking methodology
Docking studies have been performed using MOE 2008.10. With
this purpose, crystal structure of both COX-1/flurbiprofen (a non-
selective inhibitor) and COX-2/SC-558 (a selective inhibitor)
complexes (PDB codes: 1EQH and 1CX2, respectively) were
obtained from the Protein Data Bank in order to prepare both
proteins for docking studies. Docking procedure was followed using
the standard protocol implemented in MOE 2009.10 and the
geometry of resulting complexes was studied using the MOE’s Pose
Viewer utility.
Acknowledgments
Our sincere acknowledgments to Chemical Computing Group
Inc, 1010 Sherbrooke Street West, Suite 910, Montreal H3A 2R7,
Canada, for its valuable agreement to use the package of MOE
2008.10 software.
were tried in three graded doses to determine the ED50
.
5.3. Analgesic activity
Swiss albino mice were divided into 6 groups, each comprised 6
mice, and received orally the tested compounds and diclofenac
sodium. After 2 h, 0.2 mL of acetic acid 3% was injected intraperi-
toneally into each mouse. The number of writhing in 20 min after
treatment was calculated and the percentage reduction in number
of writhes from the control group was calculated and used as
a measure of the analgesic activity [31].
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