Synthesis and biological evaluation of 5-fluoroquinolone-3-carboxylic acids as potential HIV-1 integrase inhibitors

Article abstract of DOI:10.3109/14756366.2012.668540

A series of new quinolone-3-carboxylic acids as HIV-1 integrase inhibitors featuring a fluorine atom at C-5 position were synthesized and evaluated for their antiviral activity in C8166 cell culture. These newly synthesized compounds showed anti-HIV activ

Full text of DOI:10.3109/14756366.2012.668540

Journal of Enzyme Inhibition and Medicinal Chemistry, 2013; 28(4): 671–676
© 2013 Informa UK, Ltd.
ISSN 1475-6366 print/ISSN 1475-6374 online
DOI: 10.3109/14756366.2012.668540
RESEARCH ARTICLE
Synthesis and biological evaluation of 5-fluoroquinolone-
3-carboxylic acids as potential HIV-1 integrase inhibitors
Qiu-Qin He1, Xuan Zhang2,3, Liu-Meng Yang2, Yong-Tang Zheng2, and Fener Chen1
1Department of Chemistry, Fudan University, Shanghai, P R China, 2Key Laboratory of Animal Models and Human
Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese
Academy of Sciences, Kunming, P R China, and 3Faculty of Pharmacy, Kunming Medical University, Kunming,
P R China
Abstract
A series of new quinolone-3-carboxylic acids as HIV-1 integrase inhibitors featuring a fluorine atom at C-5 position
were synthesized and evaluated for their antiviral activity in C8166 cell culture. These newly synthesized compounds
showed anti-HIV activity against wild-type virus with an EC50 value ranging from 29.85 to 0.032 μΜ. The most active
compound 4e exhibited activity against wild-type virus and the mutant virus A17 with an EC50 value of 0.032 and
0.082 μΜ, respectively. Preliminary structure–activity relationship of these 5-fluoroquinolone-3-carboxylic acids was
also investigated.
Keywords: HIV-1 integrase inhibitor, 5-fluoroquinolone-3-carboxylic acids, anti-HIV activity, metal chelating,
structure–activity relationship
Introduction
low micromolar to submicromolar EC50 values against
HIV-1 virus12,13. Among these 5-hydroxylquinolone ana-
logues, the most active compound 3e characterized by a
hydroxymethyl moiety at the 1S-position of the isobutyl
group exhibited 0.13 μM EC50 value12. As part of our ongo-
ing effort to find potent anti-HIV 5-substitued-quinolone
analogues, as well as the incorporation of fluorine into
the target molecules could affect a variety of properties
(e.g., enhanced binding interactions, metabolic stability,
changes in physical properties, and selective reactivities)
due to its special nature such as the high electronega-
tivity, small size, and its van der Waals radius closer to
that of oxygen14–16, a series of new 5-fluoroquinolone-3-
carboxylic acids (Figure 1) were synthesized and evalu-
ated as potential IN inhibitors.
Insertion of proviral DNA into the host chromosome is
a crucial step in the HIV replication cycle. is process
is catalyzed by virally encoded and packaged enzyme,
namely HIV integrase (IN)1,2. e recent approval of
Raltegravir (Figure 1)3–5 by FDA and the encouraging
late-stage clinical trials with Elvitegravir (Figure 1)6,7 have
validated IN as a novel HIV therapeutic target.
Elvitegravir and its derivatives, firstly reported by Sato
et al. in 2006, have emerged as promising therapeutic IN
inhibitors, due to their high activity and favorable phar-
macokinetic property8. Subsequent chemical modifica-
tions of their quinolone core focused on N-1, C-6, 7 and
8 position have been introduced in order to obtain more
potent and selective IN inhibitors9–11. However, very few
modifications have been carried out at the C-5 position.
Considering the above facts, we have focused our
attention on the introduction of the substituent at the
C-5 position. Very recently, we identified a series of
5-hydroxylquinolone-3-carboxylic acids (Figure 1) with
Chemistry
Two
series
of
5-fluoroquinolone-3-carboxylic
acids (N-alkyl-substituted compounds 4a–e and
Address for Correspondence: Professor Fener Chen, Department of Chemistry, Fudan University; Shanghai 200433, P R China. Tel: +86 21
65643809. Fax: +86 21 65643811. E-mail: rfchen@fudan.edu.cn
(Received 20 January 2012; revised 13 February 2012; accepted 13 February 2012)
671

672 Q.-Q. He et al.
Figure 1. Chemical structures of HIV-1 IN inhibitors.
Scheme 1. Reagents and conditions.
N-aryl-substituted compounds 4f–n) were synthesized
similar to our previously reported protocol12,13 as
depicted in Scheme 1. Compound 8 were prepared
starting from 2, 6-difluoro-3-iodobenzoate according
to reported procedures12. Condensation of 8 with N,
N-dimethylformamide dimethyl acetal and followed by
substitution with appropriate amines led to acrylates
9a–n, which were then cyclized using 1,8-Diaza-
bicycloundec-7-ene as a base to furnish quinolone esters
10a–n. Ester hydrolysis of 10a–n with satd aq LiOH
afforded the target compounds.
C8166 cells infected with the wild-type HIV-1 (LAI strain
IIIB) and HIV-1 mutant virus (A17). Elvitegravir and 3e12
were included as the reference compounds. e results,
expressed as EC50, CC50 and SI, are illustrated in Table 1.
e newly synthesized quinolone-3-carboxylic acids
4a–n exhibited EC50 values against HIV-1 IIIB in the range
of 0.032–29.85 μM. Compound 4a, bearing a propyl
group at N-1 position of quinolone core, showed antiviral
activity with 13.44 μM EC50 value. e replacement of
straight chain alkyl group of 4a with branched (4b)
or cyclic one (4c) led to an improvement of antiviral
activity against wild-type HIV-1 IIIB. Compound 4d with
an i-butyl group at N-1 position showed more potent
than i-propyl counterparts (4b). e introduction of a
hydroxymethyl group at the 1S-position of butyl moiety
significantly further enhanced its potency. Compound
4e was the most active of this new series and was more
potent than the reference compound 3e. ese results
Results and discussion
Biological evaluation
All the target compounds were evaluated by 3-(4,
5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bro-
mide assay17,18 for cytotoxicity and antiviral activity in
Journal of Enzyme Inhibition and Medicinal Chemistry

5-Fluoroquinolone-3-carboxylic acids as HIV-1 IN inhibitors 673
Table 1. Anti-HIV-1 activity and cytotoxicity of compounds 4a–n in C8166 cellsa.
EC50b (μM)
Compound
R1
IIIB
13.44
4.18
2.90
2.49
0.032
29.85
9.98
3.26
9.59
3.82
2.47
21.91
11.89
3.52
0.13
A17
ND
CC50c (μM)
23.27
SId
1.73
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
3e
n-Propyl
i-Propyl
ND
92.19
22.06
>176.83
19.38
1295.90
2.52
Cyclopropyl
2.69
>512.82
48.25
i-Butyl
20.20
0.082
79.09
24.23
6.85
2S-1-hydroxy-3-methylbutan-2-yl
o-Chlorophenyl
m-Chlorophenyl
p-Chlorophenyl
p-Fluorophenyl
p-Bromophenyl
p-Trifluoromethylphenyl
m-Methylphenyl
p-Methylphenyl
2,6-Dimethylphenyl
41.08
75.20
22.93
2.30
26.50
8.13
15.09
6.57
45.65
4.76
28.97
7.58
15.22
31.02
52.09
22.16
0.078
0.00096
23.08
9.34
57.07
2.60
65.70
5.53
46.54
13.22
961.77
81904.76
125.03
17.20
Elvitegravir
0.00021
aAll data represent mean values from at least two separate experiments.
bEC50: compound concentration required to protect the cell against viral cytopathogenicity by 50% in C8166 cells.
cCC50: compound concentration that decreases the normal uninfected C8166 cell viability by 50%.
dSI: selectivity index; ratio CC50/EC50 (wild-type).
ND, not determined.
are consistent with the SAR for the 5-hydroxylquinolone
analogues that the replacement of straight chain alkyl
group with branched ones caused an increase in antiviral
activity and the introduction of a hydroxymethyl group
at the 1S-position of butyl moiety resulted in significant
improvement of activity12.
For the N-aryl-substituted compounds 4f–n, p-chloro
compound 4h showed higher activity against both
wild-type HIV-1 IIIB and HIV-1 mutant virus A17 than
o-chloro (4f) and m-chloro (4g) compounds. Since the
effect of the introduction of a withdrawing group at the
para position was marked, a fluoro (4i), a bromo (4j),
or a trifluoromethyl (4k) was introduced. Among these
compounds, only 4k exhibited slightly increased activity
against HIV-1 IIIB compared to 4h. e introduction of a
methyl group at the para position resulted in 4m, which
showed less potent than 4h; however, the introduction of
dual methyl group at ortho position (4n) led to compa-
rable activity to 4h.
IN CCD/DNA complex, atomic charges were recalculated
by Kollman all-atom for the protein and Gasteiger-Hückel
for ligand. e protomol generated using a threshold of
0.50 and bloat of zero (default values). Other parameters
were set as defaults for Surflex-Dock. e docking results
showed that 4-ketone and 3-carboxylate in compound 4e
could form Mg2+ chelation with HIV-1 IN (Figure 2a). e
quinolone ring exhibit π–π stacking interaction with A17,
like 3e and Elvitegravir do (Figure 2b and 2c). No interac-
tion could be detected between the substituent on N-1 or
C-5 fluoro atom and IN. Although the anti-HIV activity of
3e (Figure 2b) might involve a two-metal chelating mecha-
nism12, 4e showed more potent against HIV-1 IIIB than
3e, this might due to the incorporation of fluorine into 4e
favorite its physicochemical properties.
Conclusions
In conclusion, we designed and synthesized a series
of new 5-fluoroquinolone-3-carboxylic acids. All the
compounds showed moderate to good activity against
wild-type virus with an EC50 value ranging from 29.85
to 0.032 μM. Compound 4e was identified as the most
active compound of this new series (EC50 = 0.032 μM,
SI = 1295.90) associated with high activity against HIV-1
mutant strain A17 (EC50 = 0.082 μM). Preliminary struc-
ture–activity relationship of the newly synthesized qui-
nolone analogues was also investigated.
Molecular modeling calculations
In an attempt to investigate the binding model of our
newly synthesized compounds with IN, molecular dock-
ing study was performed.
Compound 4e, which displayed the most activity
against both wild-type HIV-1 and the mutant virus A17, was
docked into our previously constructed model of the HIV-1
IN catalytic core domain (CCD)/viral DNA complex12 using
SURFLEX-DOCK SYBYLX 1.1. For comparison, the bind-
ing modes of Elvitegravir and 3e were also investigated. All
the molecules were energy minimized by the conjugated
gradient method with Gasteiger-Hückel charge until a con-
vergence value of 0.01 kcal/(Å mol), using the Tripos force
field. After the hydrogen atoms were added to the HIV-1
Experimental
General procedures
Melting points were measured on a WRS-1 digital melt-
1
ing point apparatus and are uncorrected. H NMR and
© 2013 Informa UK, Ltd.

674 Q.-Q. He et al.
Figure 2. Binding models of compounds (a) 4e, (b) 3e and (c) Elvitegravirin the active site of new homoly model of HIV-1 IN.
13C NMR spectra on a Brucker AV 400 MHz spectrometer
were recorded in CDCl3. Chemical shifts are reported in δ
(ppm) units relative to the internal standard tetramethyl-
silane. Mass spectra were obtained on an Agilent MS/5975
mass spectrometer. All chemicals and solvents used were
of reagent grade and were purified and dried by standard
methods before use. All air-sensitive reactions were run
under a nitrogen atmosphere. All the reactions were
monitored by thin layer chromatography on pre-coated
silica gel G plates at 254 nm under a UV lamp using ethyl
acetate/hexane as eluents. Flash chromatography separa-
tions were obtained on silica gel (300–400 mesh).
and poured into ice-water. e mixture was extracted
by dichloromethane (5 mL × 3). e combined organic
solution was washed with brine (5 mL × 2), dried over
MgSO4 and concentrated under reduced pressure. e
residue was purified by column chromatography (silica
gel, petroleum ether/ethyl acetate 5/1 to 3/1, v/v) to give
the desired compound 10a–n.
General procedure for the preparation of 4a–n
To a solution of satd aq LiOH (5 mL) in dioxane (8 mL)
was added 10a–n (1.2 mmol). After being stirred at 50°C
for 3 h, the mixture was cooled, poured into ice-water and
acidified with 4 M HCl to pH ~2. e resulting precipitate
was collected by filtration, washed by water and ethanol,
dried to give the desired compound 4a–n.
General procedure for the preparation of 9a–n
A
mixture of 2-(3-(3-Chloro-2-fluorobenzyl)-2,6-
difluoro benzoyl)-3-(dimethylamino) acrylate 8 (618
mg, 1.5 mmol) and appropriate amines (1.8 mmol) in
tetrahydrofuran (15 mL) was stirred at 50°C for 5–10 min
and then concentrated under reduced pressure. e
resulting residue 9a–n was used directly for the next step
without further purification.
6-(3-chloro-2-fluorobenzyl)-5-fluoro-4-oxo-1-propyl-1,
4-dihydroquinoline-3-carboxylic acid (4a) Yield 75%.
1
Mp 192–193°C. H NMR (CDCl3) δ 1.01–1.05 (t, 3 H, J =
7.2 Hz, CH3), 1.92–1.97 (m, 2 H, CH2), 4.14 (s, 2 H, CH2),
4.22–4.26 (t, 2 H, J = 7.2 Hz, CH2), 7.01–7.04 (t, 1 H, J =
8.0 Hz, ArH), 7.17–7.21 (m, 1 H, ArH), 7.26–7.30 (m, 1 H,
ArH), 7.32–7.35 (d, J = 8.8 Hz, 1 H, ArH), 7.65–7.66 (m, 1
H, ArH), 8.65 (s, 1 H, CH), 14.84 (s, 1 H, COOH). MS (ESI)
General procedure for the preparation of 10a–n
A mixture of 9a–n (1.0 mmol) and K2CO3 (2.5 mmol)
in DMF (15 mL) was stirred at 60°C overnight, filtered
Journal of Enzyme Inhibition and Medicinal Chemistry

5-Fluoroquinolone-3-carboxylic acids as HIV-1 IN inhibitors 675
m/z 392 [M+H]+. Anal. Calcd for C20H16ClF2NO3: C 61.31,
H 4.12, N 3.58, found: C 61.59, H 4.36, N 3.32.
7.70–7.73 (m, 1 H, ArH), 8.65 (s, 1 H, CH), 14.66 (s, 1
H, COOH); MS (ESI) m/z 460 [M+H]+. Anal. Calcd for
C23H13Cl2F2NO3: C 60.02, H 2.85, N 3.04, Found: C 59.81,
H 3.11, N 3.28.
6-(3-chloro-2-fluorobenzyl)-5-fluoro-1-isopropyl-4-oxo-
1,4-dihydroquinoline-3-carboxylic acid (4b) Yield 82%.
1
Mp 227–229°C. H NMR (CDCl3) δ 1.63–1.65 (d, 6 H, J =
6-(3-chloro-2-fluorobenzyl)-1-(3-chlorophenyl)-5-fluoro-
4-oxo-1,4-dihydroquinoline-3-carboxylic acid (4g) Yield
89%. Mp 215–217°C. 1H NMR (CDCl3) δ 4.06 (s, 2 H, CH2),
6.79–6.81 (d, J = 8.8 Hz, 1 H, ArH), 6.83–7.05 (m, 4 H,
ArH), 7.20–7.35 (m, 3 H, ArH), 7.45–7.47 (d, J = 8.8 Hz, 1
H, ArH), 8.81 (s, 1 H, CH), 13.24 (s, 1 H, COOH); MS (ESI)
m/z 460 [M+H]+. Anal. Calcd for C23H13Cl2F2NO3: C 60.02,
H 2.85, N 3.04, Found: C 60.31, H 2.66, N 3.25.
6.0 Hz, 2CH3), 4.15 (s, 2 H, CH2), 4.94–4.96 (m, 1 H, CH),
7.01–7.05 (t, 1 H, J = 8.0 Hz, ArH), 7.18–7.22 (m, 1 H, ArH),
7.26–7.30 (m, 1 H, ArH), 7.47–7.49 (d, J = 8.8 Hz, 1 H,
ArH), 7.67–7.71 (m, 1 H, ArH), 8.85 (s, 1 H, CH), 14.93 (s,
1 H, COOH). MS (ESI) m/z 392 [M+H]+. Anal. Calcd for
C20H16ClF2NO3: C 61.31, H 4.12, N 3.58, found: C 61.52, H
3.86, N 3.35.
6-(3-chloro-2-fluorobenzyl)-1-cyclopropyl-5-fluoro-4-oxo-
6-(3-chloro-2-fluorobenzyl)-1-(4-chlorophenyl)-5-fluoro-
1,4-dihydroquinoline-3-carboxylic acid (4c) Yield 80%.
4-oxo-1,4-dihydroquinoline-3-carboxylic acid (4h) Yield
1
Mp 239–240°C. H NMR (CDCl3) δ 1.18–1.19 (d, 2 H, J =
1
90%. Mp >250°C. H NMR (CDCl3) δ 4.16 (s, 2 H, CH2),
3.2 Hz, CH2), 1.39–1.40 (d, 2 H, J = 3.2 Hz, CH2), 3.54–3.57
(m, 1 H, CH), 4.15 (s, 2 H, CH2), 7.00–7.04 (t, 1 H, J = 8.0
Hz, ArH), 7.17–7.21 (m, 1 H, ArH), 7.26–7.30 (m, 1 H,
ArH), 7.67–7.71 (m, 1 H, ArH), 7.83–7.85 (d, J = 8.8 Hz, 1
H, ArH), 8.80 (s, 1 H, CH), 14.72 (s, 1 H, COOH). MS (ESI)
m/z 390 [M+H]+. Anal. Calcd for C20H14ClF2NO3: C 61.63,
H 3.62, N 3.59, found: C 61.85, H 3.38, N 3.32.
6.84–6.86 (d, J = 8.8 Hz, 1 H, ArH), 7.03–7.07 (t, J = 7.6 Hz, 1
H, ArH), 7.20–7.24 (m, 1 H, ArH), 7.31–7.33 (m, 1 H, ArH),
7.36–7.39 (d, J = 8.8 Hz, 2 H, ArH), 7.50–7.56 (m, 1 H, ArH),
7.64–7.66 (d, J = 8.8 Hz, 2 H, ArH), 8.73 (s, 1 H, CH), 14.64
(s, 1 H, COOH); MS (ESI) m/z 460 [M+H]+. Anal. Calcd for
C23H13Cl2F2NO3: C 60.02, H 2.85, N 3.04, Found: C 60.27,
H 3.09, N 2.78.
6-(3-chloro-2-fluorobenzyl)-5-fluoro-1-isobutyl-4-oxo-
6-(3-chloro-2-fluorobenzyl)-5-fluoro-1-(4-fluorophenyl)-
4-oxo-1,4-dihydroquinoline-3-carboxylic acid (4i) Yield
93%. Mp 225–227°C. 1H NMR (CDCl3) δ 4.14 (s, 2 H, CH2),
6.83–6.85 (d, J = 8.8 Hz, 1 H, ArH), 7.01–7.03 (t, J = 8.0 Hz, 1
H, ArH), 7.18–7.22 (m, 1 H, ArH), 7.26–7.30 (m, 1 H, ArH),
7.33–7.37 (m, 2 H, ArH), 7.44–7.47 (m, 2 H, ArH), 7.51–
7.55 (m, 1 H, ArH), 8.70 (s, 1 H, CH), 14.62 (s, 1 H, COOH);
MS (ESI) m/z 444 [M+H]+. Anal. Calcd for C23H13ClF3NO3:
C 62.25, H 2.95, N 3.16, Found: C 62.47, H 3.19, N 2.89.
1,4-dihydroquinoline-3-carboxylic acid (4d) Yield 82%.
1
Mp 152–154°C. H NMR (CDCl3) δ 0.99–1.01 (d, 6 H, J =
6.4 Hz, 2 CH3), 2.24–2.27 (m, 1 H, CH), 4.05–4.07 (d, 2 H,
J = 6.4 Hz, CH2), 4.14 (s, 2 H, CH2), 7.00–7.04 (t, 1 H, J =
8.0 Hz, ArH), 7.18–7.21 (m, 1 H, ArH), 7.26–7.28 (d, 1 H,
J = 6.8 Hz,ArH), 7.29–7.32 (m, 1 H, ArH), 7.65–7.66 (m, 1
H, ArH), 8.65 (s, 1 H, CH), 14.84 (s, 1 H, COOH). MS (ESI)
m/z 406 [M+H]+. Anal. Calcd for C21H18ClF2NO3: C 62.15,
H 4.47, N 3.45, found: C 62.41, H 4.68, N 3.22.
6-(3-chloro-2-fluorobenzyl)-1-(4-bromophenyl)-5-fluoro-
(S)-6-(3-chloro-2-fluorobenzyl)-5-fluoro-1-(1-hydroxy-3-
methylbutan-2-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylic
acid (4e) Yield 70%. Mp 95–97°C. H NMR (CDCl3) δ
4-oxo-1,4-dihydroquinoline-3-carboxylic acid (4j) Yield
1
88%. Mp >250°C. H NMR (CDCl3) δ 4.15 (s, 2 H, CH2),
1
6.85–6.87 (d, J = 8.8 Hz, 1 H, ArH), 7.02–7.06 (t, J = 8.0 Hz,
1 H, ArH), 7.19–7.23 (t, J = 7.2 Hz, 1 H, ArH), 7.28–7.30 (m,
1 H, ArH), 7.32–7.34 (d, J = 8.4 Hz, 2 H, ArH), 7.52–7.56 (t,
J = 8.0 Hz, 1 H, ArH), 7.80–7.82 (d, J =8.4 Hz, 2 H, ArH),
8.71 (s, 1 H, CH), 14.62 (s, 1 H, COOH). MS (ESI) m/z 504
[M+H]+. Anal. Calcd for C23H13BrClF2NO3: C 54.73, H 2.60,
N 2.78, Found: C 54.47, H 2.36, N 2.49.
0.71–0.73 (d, 3 H, J = 6.4 Hz, CH3), 1.11–1.12 (d, 3 H, J
= 6.0 Hz, CH3), 2.34 –2.35 (m, 1 H, CH), 3.74–3.77 (brs,
1 H, OH), 4.04–4.11 (m, 4 H, 2 CH2), 4.43–4.44 (m, 1 H,
CH), 6.93–6.97 (t, 1 H, J = 8.0 Hz, ArH), 7.09–7.12 (m, 1 H,
ArH), 7.19–7.22 (m, 1 H, ArH), 7.46–7.48 (d, 1 H, J = 8.8
Hz, ArH), 7.55–7.57 (m, 1 H, ArH), 8.78 (s, 1 H, CH), 15.10
(s, 1 H, COOH). MS (ESI) m/z 436 [M+H]+. Anal. Calcd for
C22H20ClF2NO4: C 60.63, H 4.63, N 3.21, found: C 60.40, H
4.36, N 3.45.
6-(3- chloro -2-fluorobenz yl)-5-fluoro -4- oxo -1-(4-
(trifluoromethyl)phenyl)-1,4-dihydroquinoline-3-carboxylic
acid (4k) Yield 85%. Mp >250°C. 1H NMR (CDCl3) δ 4.17
(s, 2 H, CH2), 6.81–6.84 (d, J = 8.8 Hz, 1 H, ArH), 7.03–7.07
(t, J = 8.0 Hz, 1 H, ArH), 7.20–7.24 (m, 1 H, ArH), 7.31–7.33
(m, 1 H, ArH), 7.53–7.57 (m, 1 H, ArH), 7.60–7.62 (d, J
= 8.4 Hz, 2 H, ArH), 7.95–7.97 (d, J = 8.4 Hz, 2 H, ArH),
8.73 (s, 1 H, CH), 14.56 (s, 1 H, COOH). MS (ESI) m/z 494
[M+H]+. Anal. Calcd for C24H13ClF5NO3: C 58.37, H 2.65, N
2.84, Found: C 58.59, H 2.38, N 2.59.
6-(3-chloro-2-fluorobenzyl)-1-(2-chlorophenyl)-5-fluoro-
4-oxo-1,4-dihydroquinoline-3-carboxylic acid (4f) Yield
1
87%. Mp 236–238°C. H NMR (CDCl3) δ 4.11–4.20 (dd, J
= 15.2, 21.6 Hz, 2 H, CH2), 6.65–6.67 (d, J = 8.8 Hz, 1 H,
ArH), 7.02–7.06 (t, J = 8.0 Hz, 1 H, ArH), 7.19–7.23 (m,
1 H, ArH), 7.27–7.31 (m, 1 H, ArH), 7.49–7.54 (m, 2 H,
ArH), 7.57–7.61 (m, 1 H, ArH), 7.63–7.67 (m, 1 H, ArH),
© 2013 Informa UK, Ltd.

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6-(3-chloro-2-fluorobenzyl)-5-fluoro-4-oxo-1-m-tolyl-1,4-
dihydroquinoline-3-carboxylic acid (4l) Yield 89%. Mp
1
218–220°C. H NMR (CDCl3) δ 2.48 (s, 3 H, CH3), 4.15
(s, 2 H, CH2), 6.90–6.92 (d, 1 H, J = 8.8 Hz, ArH), 7.02–
7.05 (t, 1 H, J = 8.0 Hz, ArH), 7.18–7.22 (m, 3 H, ArH),
7.27–7.30 (m, 1 H, ArH), 7.44–7.46 (d, 1 H, J = 8.0 Hz,
ArH), 7.49–7.52 (m, 2 H, ArH), 8.74 (s, 1 H, CH), 14.78 (s,
1 H, COOH); MS (ESI) m/z 440 [M+H]+. Anal. Calcd for
C24H16ClF2NO3: C 65.54, H 3.67, N 3.18, Found: C 65.82,
H 3.43, N 3.45.
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antibiotics. J Med Chem 2006;49:1506–1508.
9. Pasquini S, Mugnaini C, Tintori C, Botta M, Trejos A, Arvela RK et
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Synthesis and structure-activity relationship of a class of human
immunodeficiency virus type 1 integrase inhibitors. J Med Chem
2008;51:5125–5129.
6-(3-chloro-2-fluorobenzyl)-5-fluoro-4-oxo-1-p-tolyl-1,4-
dihydroquinoline-3-carboxylic acid (4m) Yield 90%. Mp
230–232°C. 1H NMR (CDCl3) δ 2.51 (s, 3 H, CH3), 4.14 (s, 2
H, CH2), 6.89–6.91 (d, 1 H, J = 8.8 Hz, ArH), 7.01–7.05 (t, 1
H, J = 8.0 Hz, ArH), 7.18–7.22 (m, 1 H, ArH), 7.26–7.28 (m,
1 H, ArH), 7.28–7.30 (d, 1 H, J = 7.6 Hz, ArH), 7.43–7.44 (d,
1 H, J = 7.6 Hz, ArH), 7.48–7.52 (m, 1 H, ArH), 8.73 (s, 1
H, CH), 14.78 (s, 1 H, COOH); MS (ESI) m/z 440 [M+H]+.
Anal. Calcd for C24H16ClF2NO3: C 65.54, H 3.67, N 3.18,
Found: C 65.28, H 3.39, N 3.42.
6-(3-chloro-2-fluorobenzyl)-1-(2,6-dimethylphenyl)-
5-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic
acid
10. Sato M, Kawakami H, Motomura T, Aramaki H, Matsuda T,
1
(4n) Yield 85%. Mp 200–202°C. H NMR (CDCl3) δ 2.01
(s, 6 H, 2CH3), 4.16 (s, 2 H, CH2), 6.64–6.67 (d, J = 8.8 Hz, 1
H, ArH), 7.04–7.07 (t, J = 8.0 Hz, 1 H, ArH), 7.22–7.32 (m, 4
H, ArH), 7.42–7.46 (m, 1 H, ArH), 7.49–7.53 (m, 1 H, ArH),
8.62 (s, 1 H, CH), 14.81 (s, 1 H, COOH); MS (ESI) m/z 454
[M+H]+. Anal. Calcd for C25H18ClF2NO3: C 66.16, H 4.00, N,
3.09, Found: C 66.42, H 3.73, N 3.31.
Yamashita
M et al. Quinolone carboxylic acids as a novel
monoketo acid class of human immunodeficiency virus type 1
integrase inhibitors. J Med Chem 2009;52:4869–4882.
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4-oxo-1,4-dihydro-1,8-naphthyridines
and
4-oxo-1,4-dihydroquinolines as HIV integrase inhibitors. Bioorg
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12. He QQ, Gu SX, Liu J, Wu HQ, Zhang X, Yang LM et al. Structural
modifications of quinolone-3-carboxylic acids with anti-HIV
activity. Bioorg Med Chem 2011;19:5039–5045.
13. He QQ, Zhang X, Wu HQ, Gu SX, Ma XD, Yang LM et al.
Synthesis and biological evaluation of HQCAs with aryl or
benzyl substituents on N-1 position as potential HIV-1 integrase
inhibitors. Bioorg Med Chem 2011;19:5553–5558.
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Declaration of interest
is project was funded by China Postdoctoral Science
Foundation (20100470625). e work was also supported
in part by grants from the National Natural Science
Foundation of China (20872018), from Chinese Academy
of Sciences (KSCX2-YW-R-185), from the Eleventh Five-
Year Key Scientific and Technological Program of China
(2009ZX09501-029), and from National Basic Research
Program of China (2009CB5223006).
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Journal of Enzyme Inhibition and Medicinal Chemistry