Synthesis, molecular modeling and anti-inflammatory screening of novel fluorinated quinoline incorporated benzimidazole derivatives using the Pfitzinger reaction

Article abstract of DOI:10.1016/j.jfluchem.2014.02.012

Several new fluorinated quinoline derivatives were synthesized and tested for their anti-inflammatory and ulcerogenic effect. A docking study on the COX-2 binding pocket was carried out for the target compounds to rationalize the possible selectivity of them against COX-2 enzyme. The most active compounds (3, 2, 7 and 11) were found to be superior to celecoxib as they were devoid of any ulcerogenic activity. Compound 3a demonstrated the highest anti-inflammatory activity as well as the best binding profiles into the COX-2 binding site. Moreover, compounds 3-12 were screened for antibacterial activity and none of them showed noteworthy activity.

Full text of DOI:10.1016/j.jfluchem.2014.02.012

Journal of Fluorine Chemistry 161 (2014) 87–94
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Synthesis, molecular modeling and anti-inflammatory screening of
novel fluorinated quinoline incorporated benzimidazole derivatives
using the Pfitzinger reaction
Said A. El-Feky a,b, , Hamdy Kh. Thabet c,d, Mustafa T. Ubeid c
*
a Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Northern Border University, PO Box 840, Rafha 91911, Saudi Arabia
b Department of Pharmaceutical Organic Chemistry, Faculty of Pharmacy, Zagazig University, Zagazig 44511, Egypt
c Department of Chemistry, Faculty of Arts and Science, Northern Border University, PO Box 840, Rafha 91911, Saudi Arabia
d Department of Chemistry, Faculty of Science, Al-Azhar University, Nasr City, Cairo 11284, Egypt
A R T I C L E I N F O
A B S T R A C T
Article history:
Several new fluorinated quinoline derivatives were synthesized and tested for their anti-inflammatory
and ulcerogenic effect. A docking study on the COX-2 binding pocket was carried out for the target
compounds to rationalize the possible selectivity of them against COX-2 enzyme. The most active
compounds (3, 2, 7 and 11) were found to be superior to celecoxib as they were devoid of any ulcerogenic
activity. Compound 3a demonstrated the highest anti-inflammatory activity as well as the best binding
profiles into the COX-2 binding site. Moreover, compounds 3–12 were screened for antibacterial activity
and none of them showed noteworthy activity.
Received 15 December 2013
Received in revised form 21 February 2014
Accepted 26 February 2014
Available online 11 March 2014
Keywords:
Fluorinated quinolines
Benzimidazoles
Triazoles
ß 2014 Elsevier B.V. All rights reserved.
Anti-inflammatory activity
1. Introduction
towards the synthesis of selective inhibitors of COX-2 by
modifying well-known non-selective agents as indomethacin
Non-steroidal anti-inflammatory drugs (NSAIDs) are widely
used for treatment of inflammation, fever and pain. However,
because NSAIDs inhibit both isoforms of cyclooxygenase (COX)
(constitutive COX-1 and responsible for cytoprotective effects;
induce COX-2 which responsible for inflammatory effects). They
are associated with well-known side effects such as gastrointes-
tinal side effects and renal function suppression [1,2]. It is known
that selective COX-2 inhibitors can provide anti-inflammatory
agents devoid of the undesirable effects associated with classical
non-selective NSAIDs [3]. In addition to the role of COX-2 in
inflammatory disorders such as rheumatoid arthritis and
osteoarthritis, it is also implicated in cancer and angiogenesis.
In this regard, several epidemiologic studies have been reported
that inhibitors of COX-2 enzyme reduce the risk of colorectal,
breast, and lung cancer, and COX-2 are expressed in these cancers
[4,5]. As a consequence, increasing interest has been shown
[6], zomepirac [7], flurbiprofen [8], meclofenamic acid [9] or the
ketoprofen [10]. From the above findings, we keep looking for
anti-inflammatory drugs (COX-2 inhibitors), which remains a
mandatory task for medicinal chemistry. The quinoline frame-
work has emerged as a new template for drug design and
identification of novel anti-inflammatory agents. They have
attracted particular attention owing to their diverse array of
pharmacological properties including the ability to target several
causes of inflammation. These include targeting of cyclooxygen-
ase-2 (COX-2, prostaglandin inhibition), phosphodiesterase
4 (PDE4, cytokine inhibition) and tumor necrosis factor (TNF)-
a
converting enzyme (TACE), as well as transient receptor
potential vanilloid 1 (TRPV1) antagonists [11].
Fluorine imparts desirable characteristics to drug by modulat-
ing both the pharmacokinetics and pharmacodynamics properties
of a drug. Incorporation of fluorine into a drug increases the
lipophilicity enhancing absorption into biological membranes
whereby its small covalent radius can facilitate docking with their
drug receptors. In fact the importance of fluorine in bioorganic and
medicinal chemistry has been demonstrated by a large number
of fluorinated compounds approved by the FDA for medical use
[12–14]. Recently, it was reported that more than 138 fluorine
*
Corresponding author at: Zagazig University, Department of Pharmaceutical
Organic Chemistry, Faculty of Pharmacy, Rafha Street, Rafha, Saudi Arabia.
Tel.: +966 567 863 215.
E-mail address: drsaid.elfeky@yahoo.com (S.A. El-Feky).
http://dx.doi.org/10.1016/j.jfluchem.2014.02.012
0022-1139/ß 2014 Elsevier B.V. All rights reserved.

88
S.A. El-Feky et al. / Journal of Fluorine Chemistry 161 (2014) 87–94
containing drugs has received FDA approval for human diseases
(of which 23, however, have been discontinued from the market),
while 33 are currently in use for veterinary applications [15,16].
These statistics make fluorine the ‘‘second-favorite substituent’’
after nitrogen in drug design.
The azole class of drugs, particularly fused imidazoles, occupy a
prominent place in medicinal chemistry because of their broad
spectrum of pharmacological activities such as anti-inflammatory,
analgesic, anticancer, antiulcer, antimicrobial, antiviral, pesticidal,
cytotoxicity and anti-arrhythmic activities [17–20]. Omeprazole,
Mebendazole, Pimobendan and Albendazole are well-known drugs
in the market which contain fused imidazoles as active core
moiety.
reaction using substituted aniline, 4-fluorobenzaldehyde, pyruvic
acid and a catalytic amount of trifluoroacetic acid in ethanol media
[17]. Infrared spectrum of compound 1 showed a characteristic
band at 3390 cmꢀ1 which is due to the –OH stretching of carboxylic
acid in addition to the presence of a band at 1690 cmꢀ1 due to C=O
stretching of acid group. 1H-NMR spectrum showed a singlet at
d
14.0 ppm corresponding to the acidic-COOH proton of quinoline,
a singlet at 8.54 ppm due to quinolone H-3 proton in addition
to the presence of multiplet at 6.95–8.2 ppm assigned to
d
d
4-fluorophenyl aromatic protons. These data were in accordance
with the reported spectral data of Isloor et al. [17].
The target quinoline incorporated benzimidazole derivative 2
was synthesized by the reaction of the acid
1 with 1,2-
Promoted by these observations and in continuation of our
research on novel quinoline [21] as well as anti-inflammatory
compounds against COX-2 [22,23], we report herein the design,
synthesis and the preliminary in vivo anti-inflammatory activity
of trisubstituted quinoline derivatives linked to different azoles
(2–12). Also, in an attempt to rationalize the possible selective
activity of the target compounds against the COX-2 enzyme, a
molecular modeling study was conducted to check the ability of
these new scaffolds to bind to the active site of COX-2 isozyme.
benzenediamine (o-phenylenediamine) in polyphosphoric acid
media. The crude product was purified by column chromatogra-
phy. Compound 2 was confirmed by the presence of absorption
band at 3350 cmꢀ1 which is due to NH stretching of benzimidazole
(Scheme 1). Compounds 3a–f were obtained by heating compound
2 with the appropriate 2-chloro-N-arylacetamides [25] in N,N-
dimethylformamide (DMF) containing anhydrous potassium
carbonate. Compounds 3a–f have benzimidazole ring in which
different quinolines were linked to it through acetamides linker
(Scheme 1).
2. Results and discussion
Compounds 3a–f were confirmed by the presence of absorption
bands at 3255 cmꢀ1 due to stretching NH, 1687 cmꢀ1 due to
stretching C=O of amide.
Quinoline-4-carboxylic acid (1) was treated with methyl iodide
in acetone in the presence of potassium carbonate to obtain the
corresponding ester (4). This ester was then hydrazinolyzed with
hydrazine hydrate in ethanol to give the corresponding carbohy-
drazide precursor (5) in good yield, and the correct synthesis of
The reaction sequence used to synthesize the target compounds
is outlined in Schemes 1–4. The versatile Pfitzinger reaction was
utilized to synthesize pertinent 6-fluoro-2-(4-fluorophenyl)quino-
line-4-carboxylic acid
1 in a very good yield by reacting
5-fluoroisatin with 4-fluoroacetophenone in aqueous ethanol
[24]. This compound has previously been produced by a Doebner
[(Schme_1)TD$FIG]
O
COOH
F
O
O
F
i
H3C
+
N
H
F
N
F
1
ii
O
Ar
N
N
N
NH
N
H
F
F
iii
N
N
F
F
3a-f
2
3a; Ar = C6H4OCH3-4
b; Ar = C6H4OCH3-2
c; Ar = C6H4CH3-2
d; Ar = C6H4CH3-4
e; Ar = C6H4COCH3-4
f; Ar = C6H5
Reagents and conditions: i; 33% KOH/EtOH, ii; o-phenylenediamine, PPA, iii; ArNHCOCH2Cl/KOH,
iv; DMF/K2CO3
Scheme 1. Synthesis of 4-(1H-benzo[d]imidazol-2-yl)-6-fluoro-2-(4-fluorophenyl)quinoline 2 and N-(substituted-phenyl)-2-(2-(6-fluoro-2-(4-fluorophenyl)-quinolin-4-
yl)-1H-benzimidazol-1-yl)acetamides 3a–f.

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S.A. El-Feky et al. / Journal of Fluorine Chemistry 161 (2014) 87–94
89
Scheme 2. Synthetic Routes for the ester 4, hydrazide 5, quinoline containing triazine 6 and triazoles 7a–d.
these two intermediates was confirmed recording IR and 1H-NMR
spectra. Infrared spectrum gave a stretching band at 1723 cmꢀ1
due to the presence of C=O of ester. 1H-NMR gave a singlet signal at
1,2,4-triazoles, pyrrole, pyrazoles and 1,3,4-oxadiazole. 1,2,4-
Triazine derivative 6 was obtained in a good yield by heating
the hydrazide 5, benzil and ammonium acetate in ethanol–water
(1:1 molar ratio) and in the presence of ZnCl2 adopting the method
of Shinde and Sangshett [26]. Notably, In this reaction water was
used as a ‘‘Green chemistry’’ solvent. s-Triazoles 7a–d were
synthesized through the reaction of the hydrazide 5 with the
appropriate phenylisothiouronium iodides [27]. IR and 1H-NMR
confirmed the structure of 7a–f.
d
4.02 indicating the 3H of –COOCH3. Infrared spectrum of
compound 5 revealed the presence of absorption band at 3330 due
to NH-stretching and 1662 cmꢀ1 due to a carbonyl group. 1H-NMR
spectrum of 5 showed a singlet at
d 4.33 ppm indicating 2H of
NH2 group and a singlet at 9.6 ppm indicating 1H, NH (D2O
d
exchangeable). Again, this intermediate (5) enabled the access
different classes of heterocycles such as 1,2,4-triazine,
Cyclocondensation of the hydrazide 5 with the appropriate
-dicarbonyl compounds; namely, acetylacetone and benzoyla-
[(chme_3)TD$FIG]
tS o
b
cetone gave the corresponding pyrazolyl derivatives 8a,b. Alter-
natively; pyrrole derivative 9 was obtained at room temperature
by treating the hydrazide 5 with 2,5-hexanedione in acetic acid
(Scheme 3). The structures of compounds 8a,b and 9 were
confirmed by elemental analyses and spectral data.
Finally, the reaction of the hydrazide 5 with carbon disulfide in
basic medium according to the method of Young and Wood [28]
gave 1,3,4-oxadizole derivative 10. Alternatively, it has been found
that the oxadiazole derivative 10 can be condensed with hydrazine
and converted to the triazole derivative 11 in a high yield. The
triazole derivative 11 undergo ring closure with carbon disulfide in
methanolic potassium hydroxide [29] and gave the s-triazolo-
[3,4]-[1,3,4]thiadiazole derivative 12 in a good yield (Scheme 4).
The structures of these targets were confirmed using IR and 1H-
NMR spectral data.
Considering the promising biological results and for the reason
of tackling the interaction mode of all the synthesized compounds
with the COX-2 enzyme, an automated molecular docking
methodology was developed. The total procedure was conducted
on an Intel Core i3, ram memory of 4 GB operating under Windows
7 using the evolutionary algorithm MolDock Optimizer and the
scoring function MolDock [GRID] as in the Molegro Virtual Docker
software, version 5.5.
The synthesized compounds were successfully docked in
the binding site with a mode related to celecoxib. The ranking
Scheme 3. Synthesis of quinoline containing pyrazoles 8a,b and pyrrole 9.

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S.A. El-Feky et al. / Journal of Fluorine Chemistry 161 (2014) 87–94
SH
SH
S
SH
N
N
N
N
O
N
N N
N
N
NH2
F
F
F
i
ii
iii
5
N
N
N
F
F
F
10
11
12
Reagents and conditions: i; reflux, ii; NH2NH2.H2O, EtOH, iii; CS2, KOH/EtOH
Scheme 4. Synthetic Routes to quinoline containing oxadiazole 10, triazole 11 and triazolo[3,4-b][1,3,4]thiadiazole-6-thiol 12.
of the total energy of binding and MolDock score was correlated to
the predicted free-energy of binding. Table 1 shows the results
of the docking procedure sorted according to MolDock score. Fig. 1
shows the superimposition of compound 3a and celecoxib inside
the binding site of COX-2. The fluoroquinoline nucleus of
compound 3a is aligned to benzene and pyrazole rings of celecoxib.
In addition, The p-methoxyphenyl group of compound 3a utilizes a
hydrophobic pocket formed by amino acids Phe191, phe195,
Phe367, Tyr 371 and Leu520.
Compounds 2, 3a–f, 6, 7a–d, 8a,b, 9, 10, 11, and 12 were
evaluated for their anti-inflammatory activity using carrageenin
induced edema bioassay method in rats [30]. Celecoxib was used as
a reference standard representing selective COX-2 inhibitor non-
steroidal anti-inflammatory agent. This paper reports a prelimi-
nary study and that, although docking experiments suggest good
interaction with the COX-2, further experiments will be necessary
to clarify the mechanism of action.
Compounds 2, 3a–f, 7a–d, and 11 all exhibited good anti-
inflammatory activity, comparable to or slightly better than
celecoxib (Table 2). This is consistent with the reported data [31]
that COX-2 activity is sensitive to the lipophilic nature of C-7 and
C-8 quinoline substituents. This adds further evidence that these
compounds may be functioning as COX-2 inhibitors. Moreover,
incorporation of fluorine may also increase lipid solubility,
thereby enhancing the rates of absorption and transportation in
vivo as reported [12]. Despite the fact that fluorine has greater
size than hydrogen, several studies have demonstrated that
fluorine is a reasonable hydrogen mimic and exerts only a minor
steric demand at a receptor sites [32]. As all compounds
exhibited a promising anti-inflammatory activity, this indicates
that fluorine at the p-position of C-2 of phenyl ring in all the
tested compounds gave a good evidence that designation of COX-
2 inhibition is sensitive to the p-position of C-2 of phenyl ring
[31].
The benzimidazole derivatives 3a–f were found to be the best
inflammation inhibitors. The higher activity of compounds 3a–f
than the non-substituted benzimidazole derivative 2 may be due
to the presence of the acetamide linker in 3a–f. Also, their ability
to get the correct conformation required for the binding might be
related to the free rotation around the methylene linker along
with the rigid carbonyl group. The overall activity of testing
compounds was 3a–f > 2 > 7a–d > 11 > 10 > 12 > 8a,b > 9 > 6
(Table 1).
The target compounds were evaluated for their ulcerogenic
potential in rat using celecoxib as a reference drug. As illustrated in
Table 3, the most active compounds 3a–f, 2, 7a–d and 11 were
devoid of any ulcerogenic activity and were found to possess low
toxicity (Ald50) 2000 mg/kg.
All the new compounds (3–12) were tested for their antibacte-
rial and antifungal activity against Staphylococcus aureus, Escher-
ichia coli and Candida albicans by measuring the inhibition zone
produced by each compound using the agar plate diffusion method
[33]. However, none of the compounds herein showed any
noteworthy activity.
[i(g._1)TD$FIG]
Table 1
Molecular docking results ranked according to MolDock score.
Compound
MolDock score
Total interaction energy (kcal/mol)
3a
3b
3c
3e
3d
12
7d
7c
7b
7a
6
ꢀ178.202
ꢀ177.551
ꢀ176.135
ꢀ173.947
ꢀ170.659
ꢀ166.224
ꢀ165.803
ꢀ161.858
ꢀ161.797
ꢀ161.757
ꢀ157.723
ꢀ149.812
ꢀ147.34
ꢀ197.336
ꢀ200.382
ꢀ197.372
ꢀ197.88
ꢀ186.968
ꢀ172.027
ꢀ183.889
ꢀ179.595
ꢀ179.604
ꢀ179.512
ꢀ196.188
ꢀ168.786
ꢀ161.046
ꢀ174.65
2
11
8b
8a
9
ꢀ146.999
ꢀ146.407
ꢀ145.892
ꢀ141.688
ꢀ129.626
ꢀ125.602
ꢀ122.705
ꢀ166.417
ꢀ168.156
ꢀ156.161
ꢀ142.753
ꢀ142.777
ꢀ141.386
10
4
Fig. 1. The molecular docking study showed that the anti COX 2 drug celecoxib (red)
superimposed onto compound 3a (black). (For interpretation of the references to
color in this figure legend, the reader is referred to the web version of this article.)
5
1

S.A. El-Feky et al. / Journal of Fluorine Chemistry 161 (2014) 87–94
91
Table 2
investigation, a new scaffold of fluorinated quinolines linked to
different heterocyclic systems were synthesized and evaluated as
possible anti-inflammatory agents. The possible selective activity
on COX-2 isozyme was checked using molecular modeling study.
Compound 3a was found to have the best anti-inflammatory
activity as well as the best binding profiles with COX-2 isozyme.
Therefore, these derivatives may represent good lead compounds
for the development of potent and selective anti-inflammatory
agents. Also, fluorine will very likely continue to contribute
significantly in drug design and discovery by playing multifaceted
roles in enhancing future medical advances [12–14].
Anti-inflammatory activity of the investigated compounds.
Compd. no.
Protection at 50 mg/kg dose (%)
2
51
3a
3b
3c
55
55
52
3d
3e
3f
52
51.5
51.5
30
6
7a
7b
7c
50.9
50.8
50.7
50.6
38
4. Experimental
7d
8a
8b
9
36
Melting points were determined on A Gallen Kamp Digital
melting point apparatus and are uncorrected. IR spectra were
determined as KBr disks on a Shimadzu FT-IR 8000 spectropho-
tometer. 1HNMR spectra were measured using Varian Gemini-300,
300 MHz spectrometers. Mass spectra (EIMs) were run on Hewlett
Packard 5988 spectrometer. Elemental analyses were carried out
at the Microanalytical center, Faculty of Science, Cairo University,
Cairo, Egypt. Progress of the reactions was monitored by TLC using
sheets precoated with UV fluorescent silica gel Merck 60 F254.
Pharmacological and antibacterial determinations were carried
out at Pharmacology and Microbiology Department, Faculty of
Veterinary medicine, Zagazig University, Egypt.
35
10
11
12
Celecoxib
44.5
50.4
40
50
Table 3
Ulcerogenic activity of the compounds 2, 3a–f, 7a–d and 11.
Compd. no.
Dose (mg/kg) ip
Ulcer production (%)
2
50
150
250
50
0
10
15
0
4.1. 6-Fluoro-2-(4-fluorophenyl)-quinoline-4-carboxylic acid (1)
3a
150
250
50
0
A mixture of 5-fluoroisatin (10 mmol), 4-fluoroacetophenone
(10 mmol) and KOH (3%, 10 ml) in ethanol (20 ml) was heated
under reflux for 18 h. The reaction mixture was concentrated
under reduced pressure was cooled, diluted with water (50 ml) and
extracted with ether (3 ꢁ 30 ml). The aqueous layer was neutral-
ized with 1 M hydrochloric acid. The precipitate was filtered,
washed with water, dried and recrystallized from ethanol. Yield
75%; mp. 187–188 8C; IR (KBr, cmꢀ1) 3390 (OH-stretching), 1690
0
3b
0
150
250
50
10
0
3c
0
150
250
50
10
0
3d
30
70
80
0
150
250
50
(C=O). 1H-NMR (DMSO-d6,
d ppm) 6.95–8.2 (m, 4H, 4-fluorophe-
3e
nyl), 8.5–8.55 (m, 2H, quinoline), 8.57 (s, 1H, quinoline), 8.6 (m, 1H,
quinoline), 14.0 (s, 1H, COOH, D2O-exchangeable); Ms: m/z = 285.
Anal. Calcd. For C16H9F2NO2: C, 67.37; H, 3.18; N, 4.91. Found: C,
67.55; H, 3.14; N, 4.68.
150
250
50
10
15
0
3f
150
250
50
0
0
7a
0
4.2. 4-(1H-Benzo[d]imidazol-2-yl)-6-fluoro-2-(4-
fluorophenyl)quinoline (2)
150
250
50
10
15
0
7b
150
250
50
0
A mixture of 1 (1 mmol), benzene-1,2-diamine (1 mmol) and
fresh polyphosphoric acid (PPA) (2 ml) were heated to 250 8C for
2 h. The reaction mixture was then poured into 20 ml of 30%
sodium carbonate solution in water. The solid product obtained
was filtered and dried. The crude product was purified by column
chromatography using pet. Ether and ethylacetate (9:1) as eluent.
Yield 60%; m.p.: 219–220 8C; IR (KBr, cmꢀ1) 3350 (–NH-stretching
0
7c
0
150
250
50
10
5
7d
0
150
250
50
0
0
11
0
for benzimidazole ring). 1H-NMR (DMSO-d6,
d ppm): 7.28–7.50 (m,
150
250
50
0
0
4H, 4-fluorophenyl), 7.66–7.81 (m, 2H, benzimidazole), 7.83–7.87
(m, 2H, benzimidazole), 8.45–8.47 (m, 2H, quinoline), 8.76 (s, 1H,
quinoline), 9.33–9.40 (m, 1H, quinoline), 13.53 (s, 1H, NH, D2O-
exchangeable); Ms: m/z = 358 (M + 1). Anal. Calcd. For C22H13F2N2:
C, 73.94; H, 3.67; N, 11.76. Found: C, 73.76; H, 3.61; N, 11.55.
Celecoxib
30
70
85
150
250
3. Conclusion
4.3. General synthetic procedure for the preparation of compounds
3a–f
The importance of the potent quinoline class of compounds has
been established in the search for effective anti-inflammatory
agents. This is exemplified by the discovery of a variety of
quinolines as inhibitors of COX receptor antagonist. In the current
A mixture of 2 (2 mmol) and the appropriate N-substituted
chloroacetamide (2 mmol) was heated under reflux for 4 h in
dimethylformamide (DMF) in the presence of anhydrous potassium

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S.A. El-Feky et al. / Journal of Fluorine Chemistry 161 (2014) 87–94
carbonate. The mixture was cooled, diluted with water and filtered.
The separated solid was washed with ethanol, dried and recrys-
tallized from DMF/ethanol mixture to afford compounds 3a–f.
(DMSO-d6, d ppm): 5.27 (s, 2H, CH2), 7.2–7.4 (m, 4H, 4-
fluorophenyl), 7.6–7.81 (m, 2H, benzimidazole), 7.81–8.0 (m, 5H,
Ar-H), 8.1–8.2 (m, 2H, benzimidazole), 8.44–8.46 (m, 2H, quino-
line), 8.73 (s, 1H, quinoline), 9.33–9.39 (m, 1H, quinoline), 10.62 (s,
1H, NH, D2O exchangeable); Ms: m/z = 490. Anal. Calcd. For
4.3.1. N-(4-Methoxyphenyl)-2-(2-(6-fluoro-2-(4-
fluorophenyl)quinolin-4-yl)-1H-benzimidazol-1-yl)acetamide (3a)
White crystals; Yield (75%); m.p.: 170–172 8C. IR (KBr, cmꢀ1):
C30H20F2N4O: C, 73.46; H, 4.11; N, 11.42. Found: C, 73.27; H, 4.02;
N, 11.26.
3250 (NH-str.), 1678 (C=O amidic); 1H-NMR (DMSO-d6,
d ppm):
3.72 (s, 3H, OCH3), 5.26 (s, 2H, CH2), 7.15–7.20 (m, 3H, Ar-H), 7.28–
7.50 (m, 4H, 4-fluorophenyl), 7.66–7.81 (m, 2H, benzimidazole),
7.83–7.87 (m, 2H, benzimidazole), 7.90–8.1 (m, 1H, Ar-H), 8.45–
8.47 (m, 2H, quinoline), 8.76 (s, 1H, quinoline), 9.33–9.4 (m, 1H,
quinoline), 10.61 (s, 1H, NH, D2O exchangeable); Ms: m/z = 520.
Anal. Calcd. For C31H22F2N4O2: C, 71.53; H, 4.26; N, 10.76. Found: C,
71.32; H, 4.18; N, 10.54.
4.4. Methyl 6-fluoro-2(4-fluorophenyl)quinoline-4-carboxylate (4)
6-Fluoro-2(4-fluorophenyl)quinoline-4-carboxylic
acid
1
(3 mmol) and potassium carbonate (15 mmol) were weighted into
a round bottom flask. Methyl iodide (15 mmol) and acetone (4 ml)
were added. The reaction mixture was refluxed with magnetic
stirring. The progress of the reaction was monitored by TLC. The
reaction was completed after 5 h. The solvent evaporated in vacuo
and water was added to the remaining mixture. The product was
collected by suction filtration and air-dried. The crude product was
separated on a silica gel column to obtain pure 4 at 80% yield. m.p.:
4.3.2. N-(2-Methoxyphenyl)-2-(2-(6-fluoro-2-(4-
fluorophenyl)quinolin-4-yl)-1H-benzimidazol-1-yl)acetamide (3b)
White crystals; Yield (77%); m.p.: 178–179 8C. IR (KBr, cmꢀ1):
3233 (NH-str.), 1688 (C=O amidic); 1H-NMR (DMSO-d6,
d
ppm):
129–130 8C. IR (KBr, cmꢀ1): 1715 (C=O); 1H-NMR (DMSO-d6,
d
3.88 (s, 3H, OCH3), 5.35 (s, 2H, CH2), 7.08–7.09 (m, 3H, Ar-H), 7.27–
7.51 (m, 4H, 4-fluorophenyl), 7.65–7.8 (m, 2H, benzimidazole),
7.82–7.85 (m, 2H, benzimidazole), 8.13–8.15 (m, 1H, Ar-H), 8.44–
8.45 (m, 2H, quinoline), 8.76 (s, 1H, quinoline), 9.33–9.4 (m, 1H,
quinoline), 10.6 (s, 1H, NH, D2O exchangeable); Ms: m/z = 520.
Anal. Calcd. For C31H22F2N4O2: C, 71.53; H, 4.26; N, 10.76. Found: C,
71.44; H, 4.21; N, 10.61.
ppm): 4.03 (s, 3H, COOCH3), 6.92–8.1 (m, 4H, 4-fluorophenyl), 8.51–
8.57 (m, 2H, quinoline), 8.54 (s, 1H, quinoline), 8.56 (m, 1H,
quinoline); Ms: m/z = 299. Anal. Calcd. For C17H11F2NO2: C, 68.23; H,
3.70; N, 4.68. Found: C, 68.11; H, 3.81; N, 4.49.
4.5. 6-Fluoro-2-(4-fluorophenyl)quinoline-4-carbohydrazide (5)
A mixture of 5 (10 mmol), hydrazine hydrate (97%, 10 ml) in
ethanol (20 ml) was heated under reflux for 7 h. After cooling, the
precipitate was filtered, washed with water and sodium bicarbon-
ate, dried and recrystallized from absolute ethanol to give 5 at 75%
yield, m.p.: 220–221 8C. IR (KBr, cmꢀ1): 3270 (NH-str.), 1645 (C=O
4.3.3. N-(o-Tolyl)-2-(2-(6-fluoro-2-(4-fluorophenyl)quinolin-4-yl)-
1H-benzimidazol-1-yl)acetamide (3c)
White crystals; Yield (76%); m.p.: 160–161 8C. IR (KBr, cmꢀ1):
3260 (NH-str.), 1694 (C=O amidic); 1H-NMR (DMSO-d6,
d ppm):
2.25 (s, 3H, CH3), 5.30 (s, 2H, CH2), 7.1–7.4 (m, 4H, 4-fluorophenyl),
7.6–7.8 (m, 2H, benzimidazole), 7.81–8.0 (m, 4H, Ar-H), 8.1–8.11
(m, 2H, Ar-H), 8.4–8.47 (m, 2H, quinoline), 8.78 (s, 1H, quinoline),
9.32–9.4 (m, 1H, quinoline), 10.61 (s, 1H, NH, D2O exchangeable);
Ms: m/z = 504. Anal. Calcd. For C31H22F2N4O: C, 73.80; H, 4.40; N,
11.10. Found C, 73.67; H, 4.31; N, 10.96.
amidic); 1H-NMR (DMSO-d6,
d ppm): 4.8 (s, 2H, NH2, D2O
exchangeable), 6.91–8.1 (m, 4H, 4-fluorophenyl), 8.51–8.57 (m,
2H, quinoline), 8.59 (s, 1H, quinoline), 8.7 (m, 1H, quinoline), 10.0
(s, 1H, NH, D2O exchangeable). Anal. Calcd. For C16H11F2N3O: C,
64.21; H, 3.70; N, 14.04. Found: C, 64.11; H, 3.62; N, 13.88.
4.6. 6-Fluoro-2-(4-fluorophenyl)-4-(5,6-diphenyl-1,2,4-triazin-3-
4.3.4. N-(p-Tolyl)-2-(2-(6-fluoro-2-(4-fluorophenyl)quinolin-4-yl)-
1H-benzimidazol-1-yl)acetamide (3d)
yl)-quinoline (6)
White crystals; Yield (79%); m.p.: 165–166 8C. IR (KBr, cmꢀ1):
A mixture of 5 (10 mmol), benzil (10 mmol) and ammonium
acetate (10 mmol) were heated in ethanol–water (1:2 molar ratio)
using 20% mol zinc chloride. The reaction was completed after 5 h,
and left to cool. The reaction mixture was poured into crushed ice
and extracted with CH2Cl2 (2 ꢁ 50 ml). The organic extract was
washed with water, dried over anhydrous Na2SO4 and evaporated
under reduced pressure. The crude product was purified by
recrystallization from aqueous ethanol to give 6 at 75% yield as
white crystals. M.p.: 250–251 8C. IR (KBr, cmꢀ1): 3066 (CH-arom.),
3261 (NH-str.), 1695 (C=O amidic); 1H-NMR (DMSO-d6,
d ppm):
2.25 (s, 3H, CH3), 5.26 (s, 2H, CH2), 7.3–7.5 (m, 4H, 4-fluorophenyl),
7.66–7.81 (m, 2H, benzimidazole), 7.82–8.0 (m, 4H, Ar-H), 8.1–8.20
(m, 2H, benzimidazole), 8.44–8.47 (m, 2H, quinoline), 8.76 (s, 1H,
quinoline), 9.33–9.39 (m, 1H, quinoline), 10.62 (s, 1H, NH, D2O
exchangeable); Ms: m/z = 504. Anal. Calcd. For C31H22F2N4O: C,
73.80; H, 4.40; N, 11.10. Found: C, 73.69; H, 4.28; N, 10.95.
4.3.5. N-(4-Acetylphenyl)-2-(2-(6-fluoro-2-(4-
1620 (C=N amidic); 1H-NMR (DMSO-d6,
d ppm): 6.8–7.0 (m, 10H,
fluorophenyl)quinolin-4-yl)-1H-benzimidazol-1-yl)acetamide (3e)
White crystals; Yield (80%); m.p.: 180–181 8C. IR (KBr, cmꢀ1):
3225 (NH-str.), 1710 (C=O acetyl), 1670 (C=O amidic); 1H-NMR
Ar-H), 7.1–8.1 (m, 4H, 4-fluorophenyl), 8.51–8.57 (m, 2H,
quinoline), 8.59 (s, 1H, quinoline), 8.7 (m, 1H, quinoline). Anal.
Calcd. For C30H18F2N4: C, 76.26; H, 3.84; N, 11.86. Found: C, 76.11;
H, 3.68; N, 11.71.
(DMSO-d6,
d ppm): 2.78 (s, 3H, CH3), 5.32 (s, 2H, CH2), 7.2–7.4 (m,
4H, 4-fluorophenyl), 7.65–7.8 (m, 2H, benzimidazole), 7.81–8.2 (m,
4H, Ar-H), 8.2–8.25 (m, 2H, benzimidazole), 8.43–8.48 (m, 2H,
quinoline), 8.78 (s, 1H, quinoline), 9.33–9.39 (m, 1H, quinoline),
10.63 (s, 1H, NH, D2O exchangeable); Ms: m/z = 532. Anal. Calcd.
For C32H22F2N4O2: C, 72.17; H, 4.16; N, 10.52. Found: C, 72.06; H,
4.10; N, 10.38.
4.7. General procedure for the preparation of compounds 7a–d
A mixture of the appropriate aryl S-methylisothiouronium
iodide (10 mmol) and the acid hydrazide 5 (10 mmol) in pyridine
(10 ml) was refluxed for 8 h. The cooled reaction mixture was
poured into crushed ice and extracted with CH2Cl2 (2 ꢁ 50 ml).
The organic extract was washed with water. Dried over anhydrous
Na2SO4 and evaporated under reduced pressure. The crude
products were separated on a silica gel column to obtain pure
7a–d.
4.3.6. N-(Phenyl)-2-(2-(6-fluoro-2-(4-fluorophenyl)quinolin-4-yl)-
1H-benzimidazol-1-yl)acetamide (3f)
White crystals; Yield (70%); m.p.: 164–165 8C. IR (KBr, cmꢀ1):
3285 (NH-str.), 1690 (C=O acetyl), 1670 (C=O amidic); 1H-NMR

S.A. El-Feky et al. / Journal of Fluorine Chemistry 161 (2014) 87–94
93
4.7.1. N-(4-Chlorophenyl)-5-(6-fluoro-2-(4-fluorophenyl)quinolin-
4-yl)-4H-1,2,4-triazol-3-amine (7a)
8.6 (m, 1H, quinoline); Ms: m/z = 425. Anal. Calcd. For
26H17F2N3O: C, 73.40; H, 4.03; N, 9.88. Found: C, 73.28; H,
3.92; N, 9.67.
C
White crystals; yield (78%); m.p.: 290–291 8C; IR (KBr, cmꢀ1
)
3410, 3298 (NH-str.). 1H-NMR (DMSO-d6,
d ppm): 7.15–7.20 (m,
4H, Ar-H); 7.28–7.49 (m, 4H, 4-fluorophenyl), 8.51–8.55 (m, 2H,
quinoline), 8.54 (s, 1H, quinoline), 8.56 (m, 1H, quinoline), 9.77 (s,
1H, NH, D2O-exchangeable), 14.2 (s, 1H, NH, D2O-exchangeable).
Anal. Calcd. For C23H14ClF2N5: C, 63.68; H, 3.25; N, 16.14. Found: C,
63.48; H, 3.12; N, 16.10.
4.9. N-(2,5-Dimethyl-1H-pyrrol-1-yl)-6-fluoro-2-(4-fluorophenyl)-
quinoline-4-carboxamide (9)
A mixture of hydrazide 5 (2 mmol) and 2,5-hexanedione
(0.25 ml, 2 mmol) in glacial acetic acid (5 ml) was stirred at room
temperature overnight. On dilution with water, the separated solid
was filtered off and recrystallized from ethanol to give 9 as a white
crystals at (82%) yield, m.p.: 170–171 8C; IR (KBr, cmꢀ1) 3290 (NH-
4.7.2. N-(4-Bromorophenyl)-5-(6-fluoro-2-(4-
fluorophenyl)quinolin-4-yl)-4H-1,2,4-triazol-3-amine (7b)
White crystals; yield (75%); m.p.: 260–261 8C; IR (KBr, cmꢀ1
)
str.), 1685 (C=O amidic); 1H-NMR (DMSO-d6,
d ppm): 2.18 (s, 6H,
3421, 3282 (NH); 1H-NMR (DMSO-d6,
d
ppm): 7.0–7.15 (m, 4H, Ar-
2CH3), 5.63 (s, 2H, 2 =CH), 6.95–8.2 (m, 4H, 4-fluorophenyl), 8.5–
8.55 (m, 2H, quinoline), 8.57 (s, 1H, quinoline), 8.58 (m, 1H,
quinoline), 11.20 (s, 1H, NH, D2O exchangeable); Ms: m/z = 377.
Anal. Calcd. For C22H17F2N3O: C, 70.02; H, 4.54; N, 11.13. Found: C,
70.11; H, 4.39; N, 11.02.
H); 7.28–7.49 (m, 4H, 4-fluorophenyl), 8.50–8.59 (m, 2H, quino-
line), 8.54 (s, 1H, quinoline), 8.56 (m, 1H, quinoline), 9.75 (s, 1H,
NH, D2O-exchangeable), 14.1 (s, 1H, NH, D2O-exchangeable). Anal.
Calcd. For C23H14BrF2N5: C, 57.76; H, 2.95; N, 14.64. Found: C,
57.52; H, 2.72; N, 14.49.
4.10. 5-(2-(4-Fluorophenyl)-6-fluoro-quinolin-4-yl)-1,3,4-
4.7.3. N-(p-Tolyl)-5-(6-fluoro-2-(4-fluorophenyl)quinolin-4-yl)-4H-
1,2,4-triazol-3-amine (7c)
oxadiazole-2-thiol (10)
White crystals; yield (70%); m.p.: 256–257 8C; IR (KBr, cmꢀ1
)
The acid hydrazide 5 (2 mmol) was stirred in ethanol (30 ml)
containing potassium hydroxide (2 mmol) for 1 h until a clear
solution was obtained. Carbon disulfide (5 mmol) was added drop
wise to the reaction mixture with stirring and heated under reflux
for 8 h with stirring. The reaction mixture was concentrated,
cooled and acidified with dil. HCl and the separated product was
filtered, washed with water and recrystallized from ethanol/H2O to
give 10 as yellow crystals at 71% yield, m.p.: 281–282 8C; IR (KBr,
3387, 3286 (NH-str.); 1H-NMR (DMSO-d6,
d ppm): 2.27 (s, 3H,
CH3), 6.9–7.0 (m, 4H, Ar-H); 7.1–7.3 (m, 4H, 4-fluorophenyl), 8.49–
8.5 (m, 2H, quinoline), 8.54 (s, 1H, quinoline), 8.56 (m, 1H,
quinoline), 9.48 (s, 1H, NH, D2O-exchangeable), 14.0 (s, 1H, NH,
D2O-exchangeable). Anal. Calcd. For C24H17F2N5: C, 69.72; H, 4.14;
N, 16.94. Found: C, 69.88; H, 4.22; N, 16.77.
4.7.4. N-(4-Methoxy)-5-(6-fluoro-2-(4-fluorophenyl)quinolin-4-yl)-
4H-1,2,4-triazol-3-amine (7d)
cmꢀ1) 2850 (SH); 1H-NMR (DMSO-d6,
d ppm): 6.99–8.3 (m, 4H, 4-
fluorophenyl), 8.5–8.55 (m, 2H, quinoline), 8.57 (s, 1H, quinoline),
8.7 (m, 1H, quinoline), 14.1 (bs, 1H, SH, D2O exchangeable). Anal.
Calcd. For C17H9F2N3OS: C, 59.82; H, 2.66; N, 12.31. Found: C,
59.46; H, 2.51; N, 12.14.
White crystals; yield (70%); m.p.: 240–241 8C; IR (KBr, cmꢀ1
)
3387, 3286 (NH-str.); 1H-NMR (DMSO-d6,
d ppm): 3.98 (s, 3H,
OCH3), 6.88–7.0 (m, 4H, Ar-H); 7.1–7.2 (m, 4H, 4-fluorophenyl),
8.49–8.5 (m, 2H, quinoline), 8.54 (s, 1H, quinoline), 8.56 (m, 1H,
quinoline), 9.64 (s, 1H, NH, D2O-exchangeable), 14.18 (s, 1H, NH,
D2O-exchangeable). Anal. Calcd. For C24H17F2N5O: C, 67.13; H,
3.99; N, 16.31. Found: C, 67.22; H, 4.22; N, 16.18.
4.11. 4-Amino-5-(2-(4-fluorophenyl)-6-fluoroquinolin-4-yl)-4H-
1,2,4-triazole-3-thiol (11)
A mixture of 10 (1 mmol) and hydrazine hydrate (99%)
(1 mmol) in 50 ml dioxane was heated under reflux for 7 h. The
reaction mixture was cooled and poured on ice. The precipitate
was filtered, washed with water, dried and crystallized from
ethanol/H2O to give 11 at (60%) yield, m.p.: 280–281 8C; IR (KBr,
4.8. General procedure for the preparation of pyrazole derivatives
8a,b
A
solution of hydrazide 5 (2 mmol) was treated with
acetylacetone and/or benzoylacetone (0.5 ml, 2 mmol) in etha-
nol (10 ml). The mixture was heated under reflux for 6 h and
then poured into water. The precipitated solid was filtered off,
washed with water several times, and recrystallized from proper
solvent.
cmꢀ1) 2810 (SH); 1H-NMR (DMSO-d6,
d ppm): 3.4–3.5 (s, 2H, NH2
triazole ring), 6.99–8.3 (m, 4H, 4-fluorophenyl), 8.5–8.55 (m, 2H,
quinoline), 8.57 (s, 1H, quinoline), 8.7 (m, 1H, quinoline), 14.25
(s, 1H, SH, D2O exchangeable). Anal. Calcd. For C17H11F2N5S: C,
57.46; H, 3.12; N, 19.71. Found: C, 57.25; H, 3.22; N, 19.78.
4.8.1. 1-(2-(4-Fluorophenyl)-6-fluoroquinolin-4-carbonyl)-3,5-
4.12. 3-(2-(4-Fluorophenyl)-6-fluoroquinolin-4-yl)-
dimethyl-1H-pyrazole (8a)
[1,2,4]triazolo[3,4-b][1,3,4]-thiadiazole-6-thiol (12)
White crystals, yield (85%), m.p.: 160–161 8C; IR (KBr, cmꢀ1
)
1690 (C=O amidic); 1H-NMR (DMSO-d6,
2.55 (s, 3H, CH3), 6.30 (s, 1H, =CH), 6.95–8.1 (m, 4H, 4-
fluorophenyl), 8.5–8.56 (m, 2H, quinoline), 8.57 (s, 1H, quinoline),
8.59 (m, 1H, quinoline); Ms: m/z = 363. Anal. Calcd. For
d
ppm): 2.50 (s, 3H, CH3),
Compound 11 (10 mmol) was dissolved in a solution of
potassium hydroxide (10 mmol) in absolute ethanol (25 ml).
Carbon disulfide (15 ml) was then added and the mixture was
maintained at the reflux temperature for 18 h. The reaction
mixture was concentrated under reduced pressure and the residue
was dissolved in 10% potassium hydroxide solution and filtered.
The cold filtrate was acidified, washed with water and crystallized
from aqueous ethanol to give 12 as yellow solid at (65%) yield, m.p.:
C21H15F2N3O: C, 69.41; H, 4.16; N, 11.56. Found: C, 69.33; H,
4.25; N, 11.41.
4.8.2. 1-(2-(4-Fluorophenyl)-6-fluoroquinolin-4-carbonyl)-3-
methyl-5-phenyl-1H-pyrazole (8b)
290–291 8C; IR (KBr, cmꢀ1) 2825 (SH); 1H-NMR (DMSO-d6,
d ppm):
White crystals (82%) yield, m.p.: 175–176 8C; IR (KBr, cmꢀ1
)
6.99–8.3 (m, 4H, 4-fluorophenyl), 8.5–8.55 (m, 2H, quinoline), 8.57
(s, 1H, quinoline), 8.7 (m, 1H, quinoline), 14.3 (s, 1H, SH, D2O
exchangeable). Anal. Calcd. For C18H9F2N5S2: C, 54.40; H, 2.28; N,
17.62. Found: C, 54.61; H, 2.33; N, 17.49.
1690 (C=O amidic); 1H-NMR (DMSO-d6,
d ppm): 2.3 (s, 3H, CH3),
6.59 (s, 1H, =CH), 7.0–7.1 (m, 5H, Ar-H), 7.2–8.1 (m, 4H, 4-
fluorophenyl), 8.5–8.56 (m, 2H, quinoline), 8.58 (s, 1H, quinoline),

94
S.A. El-Feky et al. / Journal of Fluorine Chemistry 161 (2014) 87–94
4.12.1. Molecular modeling
salt, was used as a positive control. The plates were incubated for
24 hat37 8C. Thezoneofinhibitionofbacterialgrowth(mm)around
the disc was observed. The screening results indicated that zone of
the tested compounds showed any noteworthy activity against the
control which showed a zone of inhibition of bacterial growth equal
83 mm (Staphylococcus aureus and 17 mm Escherichia coli).
3D Structures of synthesized compounds were built using
openbabel then imported into MVD. All compounds were prepared
to assign tripos atom types and partial charges. The 3D coordinates
of the crystal Structure of celecoxib bound by the COX-2 active site
[3LN1] was used for the docking procedure. It was imported into
VMD and prepared according to the automatic preparation scheme.
All single bonds of the compounds were considered rotatable during
the docking simulation where the binding site was considered rigid.
Before docking, the reliability of the docking procedure was
validated by challenging it to predict the pose of crystalized
celecoxib upon extraction and redocking to the binding site of COX-
2. The predicted pose was very similar to the co-crystalized one with
Acknowledgements
The authors would like to express their deep gratitude to the
Northern Border University, Kingdom Saudi Arabia for providing
financial support of that research (project 434-005).
˚
RMSD value of 0.7 A. To define binding site, a sphere was built
Appendix A. Supplementary data
˚
around celecoxib with a radius of 17 A and used as a constraint for
docking. Afterthought, celecoxib was removed and synthesized
compounds were docked into the binding site using MolDock
optimizer as the search algorithm with default parameter values
except raising the population size to 100. Ten runs were conducted
for each compound returning the pose with the best MolDock score.
After docking, energy was minimized and hydrogen bonds
optimized.
Supplementary material related to this article can be found,
in the online version, at http://dx.doi.org/10.1016/j.jfluchem.
2014.02.012.
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4.12.5. Antibacterial activity
It was carried out by applying the agar plate diffusion technique
[33]. All of the newly synthesized compounds were screened in
vitro for antibacterial and antifungal activity against Staphylococ-
cus aureus, Escherichia coli and Candida albicans. In this method a
standard 6 mm agar plate discs impregnated with the test
compound (1 mg/ml of acetone) were used. Penicillin V sodium