Synthesis of zidovudine derivatives with anti-HIV-1 and antibacterial activities

Article abstract of DOI:10.1080/15257770902736442

Twelve novel zidovudine derivatives were prepared by modifying 5′-hydroxyl group of sugar moiety (1-8) and 5-methyl group of thymidine nucleus (9-12) and characterized spectrally. The compounds were evaluated for anti-HIV-1, antitubercular and antibacteri

Full text of DOI:10.1080/15257770902736442

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Synthesis of Zidovudine Derivatives with
Anti-HIV-1 and Antibacterial Activities
Palaniappan Senthilkumar a , Jing Long b , Raparla Swetha a ,
Vaidyanathan Shruthi a , Rui-Rui Wang b , Srinivasan Preethi a ,
Perumal Yogeeswari a , Yong-Tang Zheng b & Dharmarajan Sriram a
a Medicinal Chemistry & Antimycobacterial Research Laboratory,
Pharmacy Group, Birla Institute of Technology & Science–Pilani,
Hyderabad Campus, Jawahar Nagar, Hyderabad, Andhra Pradesh,
India
b Laboratory of Molecular Immunopharmacology, Key Laboratory of
Animal Models and Human Diseases Mechanisms, Kunming Institute
of Zoology, The Chinese Academy of Sciences, Kunming, Yunnan, P.
R. China
Version of record first published: 14 Feb 2009.
To cite this article: Palaniappan Senthilkumar , Jing Long , Raparla Swetha , Vaidyanathan Shruthi ,
Rui-Rui Wang , Srinivasan Preethi , Perumal Yogeeswari , Yong-Tang Zheng & Dharmarajan Sriram
(2009): Synthesis of Zidovudine Derivatives with Anti-HIV-1 and Antibacterial Activities, Nucleosides,
Nucleotides and Nucleic Acids, 28:2, 89-102
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Nucleosides, Nucleotides and Nucleic Acids, 28:89–102, 2009
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1525-7770 print / 1532-2335 online
DOI: 10.1080/15257770902736442
SYNTHESIS OF ZIDOVUDINE DERIVATIVES WITH ANTI-HIV-1 AND
ANTIBACTERIAL ACTIVITIES
Palaniappan Senthilkumar,1 Jing Long,2 Raparla Swetha,1
Vaidyanathan Shruthi,1 Rui-Rui Wang,2 Srinivasan Preethi,1
Perumal Yogeeswari,1 Yong-Tang Zheng,2 and Dharmarajan Sriram1
1Medicinal Chemistry & Antimycobacterial Research Laboratory, Pharmacy Group, Birla
Institute of Technology & Science{Pilani, Hyderabad Campus, Jawahar Nagar, Hyderabad,
Andhra Pradesh, India
2Laboratory of Molecular Immunopharmacology, Key Laboratory of Animal Models and
Human Diseases Mechanisms, Kunming Institute of Zoology, The Chinese Academy of
Sciences, Kunming, Yunnan, P. R. China
Twelve novel zidovudine derivatives were prepared by modifying 5 ꢁ-hydroxyl group of sugar
2
moiety (1–8) and 5-methyl group of thymidine nucleus (9–12) and characterized spectrally. The
compounds were evaluated for anti-HIV-1, antitubercular and antibacterial activities. Compound
(3-azido-tetrahydro-5- (3,4-dihydro-5-methyl-2,4-dioxopyrimidin- 1 (2H)-yl) furan-2-yl)methyl 7- (4-
(2-phenylacetoyloxy) -3,5- dimethylpiperazin-1-yl) -5- (2-phenylacetoyloxyamino) -1-cyclopropyl-6,8-
difluoro-1,4-dihydro-4-oxoquinoline-3-carboxylate (5) was found to be the most potent anti-HIV-1
agent with EC50 of 0.0012 µM against HIV-1IIIB and CC50 of 34.05 µM against MT-4 with
selectivity index of 28,375. Compound 5 inhibited Mycobacterium tuberculosis with MIC of
1.72 µM and inhibited four pathogenic bacteria with MIC of less than 1 µM.
INTRODUCTION
Acquired immune deficiency syndrome (AIDS) is a collection of symp-
toms and infections resulting from the specific damage to the immune
Received 3 November 2008; accepted 10 December 2008.
P. S. and J. L. contributed equally to this work.
The authors are thankful to the Indian Council of Medical Research [No. 58/9/2003-BMS]
for their financial assistance. This study was supported by grants from the CAS (KSCX1-YW-R-24),
National 973 project of China (2006CB504200), Key Scientific and Technological projects of China
(2004BA719A14), and Yunnan (2004NG12).
Address correspondence to Dharmarajan Sriram, Medicinal Chemistry & Antimycobacterial Re-
search Laboratory, Pharmacy Group, Birla Institute of Technology & Science–Pilani, Hyderabad Campus,
Jawahar Nagar, Hyderabad–500 078, Andhra Pradesh, India. E-mail: drdsriram@yahoo.com or to Yong-
Tang Zheng, 2Laboratory of Molecular Immunopharmacology, Key Laboratory of Animal Models
and Human Diseases Mechanisms, Kunming Institute of Zoology, The Chinese Academy of Sciences,
Kunming, Yunnan650223, P. R. China. E-mail: zhengyt@mail.kiz.ac.cn
89

90
P. Senthilkumar et al.
system caused by the human immunodeficiency virus (HIV) in humans.[1]
According to the latest figures published in the UNAIDS/WHO 2006 AIDS
Epidemic Update, an estimated 39.5 million people are living with HIV.
There were 4.3 million new infections in 2006 with 2.8 million (65%) of
these occurring in sub-Saharan Africa and important increases in Eastern
Europe and Central Asia, where there are some indications that infection
rates have risen by more than 50% since 2004. In 2006, 2.9 million peo-
ple died of AIDS-related illnesses. The late stage of the HIV infection
leaves individuals prone to opportunistic infections like tuberculosis (TB),
bacterial and fungal infections. HIV and TB are lethal combination, each
speeding the other’s progress. TB is a major cause of death among people
living with HIV/AIDS. About 90% of deaths related to HIV infection and
AIDS are caused by opportunistic infections. Through logic and orderly
thinking, it appears that an ideal drug for HIV/AIDS patients should
suppress HIV replication thereby acting as anti-HIV drug and also should
treat opportunistic infections like TB and other bacterial infections.[2] To
improve antiviral activity and to obtain antibacterial activities we have sug-
gested “dual-drug” strategy that combine an HIV inhibitor zidovudine and
an antibacterial agents (fluoroquinolones) integrated into a single mole-
cule. The following advantages were envisaged for this strategy: 1) the
undesirable physicochemical property such as low membrane permeability
of zidovudine would be improved; 2) and the compounds would treat the
tuberculosis and other bacterial infections. Based on these premises, we
have developed for the first time many potent hybrid-type anti-HIV and
antimycobacterial agents.[3–7] In this article, we described the zidovudine
derivatives modified at 5-methyl group of thymidine nucleus and 5’-hydroxyl
group of sugar moiety.
RESULTS AND DISCUSSION
The general preparation of various ester derivatives of zidovudine
1–8 (Table 1) are described in (series 1) Scheme 1. N-Protected flu-
oroquinolones like norfloxacin, ciprofloxacin, lomefloxacin, gatifloxacin
and sparfloxacin and non-protected fluoroquinolones like enrofloxacin,
levofloxacin and ofloxacin reacted with thionyl chloride to activate its C-3
carboxylic acid followed by reaction with zidovudine in presence of pyridine
under microwave irradiation yielded 37–59% of esters 1–8. When compared
to conventional method of 1–2 hours process, microwave assisted synthesis
was performed with short reaction times (1–3 minutes), with ease and
was environment friendly. In the second series zidovudine was stirred with
sulfuryl chloride for 48 hours followed by reaction with fluoroquinolones
like norfloxacin, ciprofloxacin, lomefloxacin, gatifloxacin under microwave
irradiation yielded 40–54% of 9–12. The purity of the synthesized

91

92

93

94
P. Senthilkumar et al.
compounds was monitored by thin layer chromatography (TLC) and ele-
mental analyses and the structures were identified by spectral data.
In the initial phase of screening, the synthesized compounds were
evaluated for inhibitory activity against HIV-1 replication in acutely infected
C8166 cells (inhibition of syncytium formation).[8] The cellular toxicity
of compounds on C8166 cells was assessed by MTT colorimetric assay.[9]
The minimum toxic concentration that caused the reduction of viable cells
by 50% (CC50) was determined from dose-response curve. The effect of
samples on acute HIV-1 infectivity was measured by the syncytia formation
assay. The inhibitory percentage of syncytial cell formation was calculated
by the percentage of syncytial cell number in sample-treated culture
compared to that in infected control culture.[10] EC50 is the concentration
of drug that reduces syncytia formation by 50%. Zidovudine was used as a
positive control. The CC50 and EC50 were reported in Table 1. Rapid glance
of the results revealed compounds 1–8, which modified at 5’ hydroxyl
group of sugar moiety of zidovudine showed very good activity with EC50
ranging from 0.00098–0.034 µM and seven compounds were found to be
more active (1–15 folds) than zidovudine (EC50 of 0.015 µM). Compound
[3-azido-5-(5-methyl-2,4-dioxo-1,2,3,4-tetrahydro-1-pyrimidinyl)tetrahydro-
2-furanyl]methyl
9-fluoro-3-methyl-10-(4-methylpiperazino)-7-oxo-2,3-
dihydro-7H-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxylate (8) was found to
be the most active compound with EC50 of 0.00098 µM and fifteen times
more active than zidovudine. Compound 8 showed the selectivity index of
(CC50/EC50) 148,949. Compounds 9–12 which were modified at 5-methyl
group of thymidine nucleus of zidovudine do not show any promising
activity. Compounds 1, 3, 5, 6, 7, 9–11 did not show any toxicity till 200
µg/mL.
The compounds exhibited good activity or low toxicity were further
evaluated for their inhibitory effect on the replication of HIV-1IIIB
in MT-4 cell lines by MTT assay method[8] and their EC50 (effective
concentration of compound (µM) achieving 50% protection in MT-4
cell lines against the cytopathic effect of HIV-1), and CC50 (cytotoxic
concentration of compound (µM) required to reduce the viability of
mock infected MT-4 cells by 50%), are reported in the Table 1 with
zidovudine as standard drug for comparison. Rapid glance to the obtained
results revealed that the compounds 2–9 exhibited good anti-HIV activity
with EC50 ranging from 0.0012–0.033 µM. Six compounds (2–5, 7–8),
(EC50 ranging from 0.0012 to 0.0085 µM) were found to be more
potent than zidovudine (EC50 of 0.027 µM). Among the synthesized
compounds, compound [3-azido-5-(5-methyl-2,4-dioxo-1,2,3,4-tetrahydro-
1-pyrimidinyl)tetrahydro-2-furanyl]methyl 5-[(benzyloxy)carbonyl]amino-
7–4-[(benzyloxy)carbonyl]-3,5-dimethylpiperazino-1-cyclopropyl-6-fluoro-
4-oxo-1,4-dihydro-3-quinolinecarboxylate (5) was found to be the most
potent compound with EC50 of 0.0012 µM against HIV-1 replication and

Synthesis of Zidovudine Derivatives
95
CC50 of 34.05 µM against MT-4 cell lines with selectivity index (CC50 /EC50)
of >28375. Compound 5 was 22 times more active than parent zidovudine.
Compounds 9–12 which modified at 5-methyl group of thymidine nucleus
of zidovudine not showed any promising activity in this study also. When
compared to zidovudine all the compounds (except 11) were cytotoxic to
MT-4 cell lines.
With respect to the structure-activity relationship, compounds which
were modified at 5ꢁ -hydroxyl group of sugar moiety of zidovudine showed
very good activities and compounds modified at 5-methyl group of thymi-
dine nucleus of zidovudine does not show any promising activities. These
results have revealed that ester derivatives 1–8 are easily hydrolyzed by
esterases to zidovudine, which gets tri-phosphorylated and act as a com-
petitive inhibitor for HIV reverse transcriptase (RT) enzymes, whereas 5-
aminomethylated compounds 9–12 were unable to bind to the active site
pocket of HIV-RT enzyme.
The lipophilicity (ClogP) of the synthesized compounds increased
remarkably compared with the parent drug, zidovudine (Table 1). This
may render them more capable of penetrating various biomembranes,[11]
consequently improving their permeation properties through viral cell
membranes. The results showed that there was an improvement in anti-HIV
activity compared to the parent drug.
The compounds were screened for their in vitro antimycobacterial
activity against Mycobacterium tuberculosis (MTB) and M. smegmatis ATCC
14468 (MC2) by agar dilution method for the determination of MIC in
duplicate.[12] The minimum inhibitory concentration (MIC) is defined
as the minimum concentration of compound required to give complete
inhibition of bacterial growth and MICs of the synthesized compounds are
reported in Table 1. All the compounds inhibited MTB with MICs ranging
from 0.55–8.51 µM and when compared ofloxacin (MIC of 2.16 µM) two
compounds (2 and 4) were found to be more active. Compound 2 was found
to be the most active compound with MIC of 0.55 µM and was four time
more potent than ofloxacin.
All the compounds were evaluated for their in vitro antibacterial activity
against 21 pathogenic bacteria by conventional agar dilution procedures[13]
and the results of these assays are summarized in Table 2. The data for
norfloxacin, ciprofloxacin, and gatifloxacin were included for comparison.
The antibacterial activity data revealed that all the test compounds showed
mild to moderate activity against tested bacteria.
EXPERIMENTAL SECTION
Melting points were taken on an electrothermal melting point apparatus
1
(Buchi BM530) in open capillary tubes and are uncorrected. H-NMR

96

Synthesis of Zidovudine Derivatives
97
spectra were scanned on a JEOL Fx 300MHz NMR spectrometer using
DMSO-d6 as solvent. Chemical shifts are expressed in δ (ppm) relative to
tetramethylsilane. Elemental analyses (C, H, and N) were performed on
Perkin Elmer (Waltham, MA, USA) model 240C analyzer and the data were
within 0.4% of the theoretical values. The progress of the reactions and
homogeneity of the compounds were monitored by ascending thin-layer
chromatography (TLC) on silica gel G (precoated silica gel plate 60 F254
;
Merck, Whitehouse Station, NJ, USA) and visualized by using UV radiation.
Some of the reactions were carried out using microwave oven from Catalyst,
India (Pune, India). The log P values were determined using ChemDraw 8.0
software.
General Procedure for the Synthesis of Compounds 1–8
To N-protected fluoroquinolone (1.00 equiv.) was added thionyl chlo-
ride (10.00 equiv.) and the mixture was refluxed at 75◦C for 10 hrs.
The excess thionyl chloride was distilled under pressure and further used
without any purification. The resultant was reacted with zidovudine (1.00
equiv.) in dichloromethane and pyridine to yield the titled ester compounds
(1–8).
(3-Azido-tetrahydro-5-(3,4-dihydro-5-methyl-2,4-dioxopyrimidin-1(2H)-
yl)furan-2-yl)methyl 7-(4-(2-phenylacetoyloxy)piperazin-1-yl)-1-ethyl-6-fluoro
-1,4-dihydro-4-oxoquinoline-3-carboxylate (1): Yield: 50%; m.p.: 152◦C;
1H NMR (DMSO-d6) δ ppm: 1.13 (t, 3H, CH2CH3), 1.4 (s, 3H, CH3 of
pyrimidinyl ring), 2.13 (m, 1H, CH-N3), 3.15 (d, 2H, CH2CH3), 3.22 (dd,
4H, 2CH2-), 3.58 (dd, 4H, 2CH2-), 4.54 (d, 1H, CH of furyl ring), 4.85
(s, 2H, CH2), 4.88 (s, 2H, CH2 of benzyloxy), 5.62 (t, 1H, CH of furyl
ring), 5.64 (s, 2H, CH2), 7.00–7.20 (m, 5H, ArH), 8.34 (s, 1H, C8-H),
8.54 (s, 1H, CH of pyrimidinyl ring), 9.00 (s, 1H, NH of pyrimidinyl ring,
D2O exchangeable), 9.32 (s, 1H, C5-H), 9.56 (s, 1H, C2-H); m/z: 702.26
(100.0%), 703.26 (37.5%), 704.26 (9.4%), 703.25 (3.0%). Anal calc for
(C34H35FN8O8) C, 58.11, H, 5.02, N, 15.95. Found: C, 58.22, H, 5.09, N,
15.98.
(3-Azido-tetrahydro-5-(3,4-dihydro-5-methyl-2,4-dioxopyrimidin-1(2H)-
yl) furan-2-yl)methyl 7-(4-(2-phenylacetoyloxy)piperazin-1-yl)-1-cyclopropyl-
6-fluoro-1,4-dihydro -4-oxoquinoline-3-carboxylate (2): Yield: 45%; m.p.:
1
157◦C; H NMR (DMSO-d6) δ ppm: 0.28–0.52 (m, 4H, cyclopropyl), 1.38
(m, 1H, cyclopropyl), 1.4 (s, 3H, CH3 of pyrimidinyl ring), 2.13 (m, 1H,
CH-N3), 3.22 (dd, 4H, 2CH2-), 3.58 (dd, 4H, 2CH2-), 4.54 (d, 1H, CH of
furyl ring), 4.85 (s, 2H, CH2), 4.88 (s, 2H, CH2 of benzyloxy), 5.62 (t, 1H,
CH of furyl ring), 5.64 (s, 2H, CH2), 7.00–7.20 (m, 5H, ArH), 8.34 (s, 1H,
C8-H), 8.54 (s, 1H, CH of pyrimidinyl ring), 9.00 (s, 1H, NH of pyrimidinyl
ring, D2O exchangeable), 9.32 (s, 1H, C5-H), 9.56 (s, 1H, C2-H); m/z:
714.26 (100.0%), 715.26 (38.6%), 716.26 (9.9%), 715.25 (3.0%). Anal calc

98
P. Senthilkumar et al.
for (C35H35FN8O8) C, 58.82, H, 4.94, N, 15.68. Found: C, 58.22, H, 4.99, N,
15.68.
(3-Azido-tetrahydro-5-(3,4-dihydro-5-methyl-2,4-dioxopyrimidin-1(2H)-
yl)furan-2-yl)methyl 7-(4-(2-phenylacetoyloxy)-3-methylpiperazin-1-yl)-1-eth-
yl-6,8-difluoro-1,4-dihydro-4-oxoquinoline-3-carboxylate (3): Yield: 27%;
1
m.p.: 107◦C; H NMR (DMSO-d6) δ ppm: 1.13 (t, 3H, CH2CH3), 1.3 (3H,
CH3 of piperazine), 1.4 (s, 3H, CH3 of pyrimidinyl ring), 2.13 (m, 1H,
CH-N3), 3.15 (d, 2H, CH2CH3), 3.22 (dd, 4H, 2CH2-), 3.58 (dd, 4H,
2CH2–), 4.54 (d, 1H, CH of furyl ring), 4.85 (s, 2H, CH2), 4.88 (s, 2H,
CH2 of benzyloxy), 5.62 (t, 1H, CH of furyl ring), 5.64 (s, 2H, CH2),
7.00–7.20 (m, 5H, ArH), 8.54 (s, 1H, CH of pyrimidinyl ring), 9.00 (s, 1H,
NH of pyrimidinyl ring, D2O exchangeable), 9.32 (s, 1H, C5-H), 9.56 (s,
1H, C2-H); m/z: 734.26 (100.0%), 735.27 (38.6%), 736.27 (8.9%), 735.26
(3.0%), 737.27 (1.7%), 736.26 (1.2%). Anal calc for (C35H36F2N8O8) C,
57.22, H, 4.94, N, 15.25. Found: C, 57.62, H, 4.99, N, 15.28.
(3-Azido-tetrahydro-5-(3,4-dihydro-5-methyl-2,4-dioxopyrimidin-1(2H)-
yl)furan-2-yl)methyl 7-(4-(2-phenylacetoyloxy)-3-methylpiperazin-1-yl)-1-cyc-
lopropyl-6-fluoro-1,4-dihydro-8-methoxy-4-oxoquinoline-3-carboxylate (4):
1
Yield: 48%; m.p.: 103◦C; H NMR (DMSO-d6) δ ppm: 0.28–0.52 (m, 4H,
cyclopropyl), 1.3 (3H, CH3 of piperazine), 1.38 (m, 1H, cyclopropyl), 1.4
(s, 3H, CH3 of pyrimidinyl ring), 2.13 (m, 1H, CH-N3), 3.02 (t, 1H, CH–),
3.22 (dd, 2H, 2CH2–), 3.4 (s, 3H, –OCH3), 3.58 (dd, 4H, 2CH2–), 4.54 (d,
1H, CH of furyl ring), 4.85 (s, 2H, CH2), 4.88 (s, 2H, CH2 of benzyloxy),
5.62 (t, 1H, CH of furyl ring), 5.64 (s, 2H, CH2), 7.00–7.20 (m, 5H, ArH),
8.54 (s, 1H, CH of pyrimidinyl ring), 9.00 (s, 1H, NH of pyrimidinyl ring,
D2O exchangeable), 9.32 (s, 1H, C5–H), 9.56 (s, 1H, C2–H); m/z: 758.28
(100.0%), 759.29 (40.8%), 760.29 (10.0%), 759.28 (3.0%), 761.29 (2.0%),
760.28 (1.2%). Anal calc for (C37H39FN8O9) C, 58.57, H, 5.18, N, 14.77.
Found: C, 58.02, H, 5.11, N, 14.78.
(3-Azido-tetrahydro-5-(3,4-dihydro-5-methyl-2,4-dioxopyrimidin-1(2H)-
yl)furan-2-yl)methyl 7-(4-(2-phenylacetoyloxy)-3,5-dimethylpiperazin-1-yl)-5-
(2-phenylacetoyloxyamino)-1-cyclopropyl-6,8-difluoro-1,4-dihydro-4-oxoqui-
1
noline-3-carboxylate (5): Yield: 50%; m.p.: 107◦C; H NMR (DMSO-d6) δ
ppm: 0.28–0.52 (m, 4H, cyclopropyl), 1.3 (6H, 2CH3 of piperazine), 1.38
(m, 1H, cyclopropyl), 1.4 (s, 3H, CH3 of pyrimidinyl ring), 2.13 (m, 1H,
CH-N3), 3.01 (dd, 2H, 2CH-), 3.58 (dd, 4H, 2CH2–), 4.54 (d, 1H, CH of
furyl ring), 4.85 (s, 2H, CH2), 4.88 (s, 2H, CH2 of benzyloxy), 5.62 (t, 1H,
CH of furyl ring), 5.64 (s, 4H, 2CH2), 7.00–7.20 (m, 10H, ArH), 8.54 (s,
1H, CH of pyrimidinyl ring), 9.00 (s, 1H, NH of pyrimidinyl ring, D2O
exchangeable), 9.56 (s, 1H, C2-H); Anal calc for (C45H45F2N9O10) C, 59.40,
H, 4.98, N, 13.85. Found: C, 59.02, H, 4.91, N, 13.88.
(3-Azido-tetrahydro-5-(3,4-dihydro-5-methyl-2,4-dioxopyrimidin-1(2H)-
yl)furan-2-yl)methyl 1-cyclopropyl-7-(4-ethylpiperazin-1-yl)-6-fluoro-1,4-dihy-

Synthesis of Zidovudine Derivatives
99
1
dro-4-oxoquinoline-3-carboxylate (6): Yield: 42%; m.p.: 105◦C; H NMR
(DMSO-d6) δ ppm: 0.28–0.52 (m, 4H, cyclopropyl), 1.13 (t, 3H, CH2CH3),
1.38 (m, 1H, cyclopropyl), 1.4 (s, 3H, CH3 of pyrimidinyl ring), 2.13 (m,
1H, CH-N3), 3.15 (d, 2H, CH2CH3), 3.22 (dd, 4H, 2CH2-), 3.58 (dd, 4H,
2CH2-), 4.54 (d, 1H, CH of furyl ring), 4.85 (s, 2H, CH2), 5.62 (t, 1H, CH
of furyl ring), 5.64 (s, 2H, CH2), 8.34 (s, 1H, C8-H), 8.54 (s, 1H, CH of
pyrimidinyl ring), 9.00 (s, 1H, NH of pyrimidinyl ring, D2O exchangeable),
9.32 (s, 1H, C5-H), 9.56 (s, 1H, C2-H); m/z: 608.25 (100.0%), 609.25
(34.5%), 610.26 (4.9%), 610.25 (2.2%). Anal calc for (C29H33FN8O6) C,
57.23, H, 5.47, N, 18.41. Found: C, 57.52, H, 5.48, N, 18.48.
(3-Azido-tetrahydro-5-(3,4-dihydro-5-methyl-2,4-dioxopyrimidin-1(2H)-
yl)furan-2-yl)methyl 9-fluoro-3,7-dihydro-3-methyl-10-(4-methylpiperazin-1-
yl)-7-oxo-2H-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxylate (7): Yield: 59%;
m.p.: 110◦C; 1H NMR (DMSO-d6) δ ppm: 1.35 (s, 3H, CH3), 1.4 (s, 3H, CH3
of pyrimidinyl ring), 2.13 (m, 1H, CH-N3), 3.22 (dd, 4H, 2CH2-), 3.58 (dd,
4H, 2CH2-), 4.12 (m, 1H, -CHCH3), 4.54 (d, 1H, CH of furyl ring), 4.85
(s, 2H, CH2), 5.32 (d, 1H, CH of CH2 of oxazino ring), 5.46 (d, 1H, CH
of CH2 of oxazino ring), 5.62 (t, 1H, CH of furyl ring), 5.64 (s, 2H, CH2),
8.54 (s, 1H, CH of pyrimidinyl ring), 9.00 (s, 1H, NH of pyrimidinyl ring,
D2O exchangeable), 9.32 (s, 1H, C5-H), 9.56 (s, 1H, C2-H); m/z: 610.23
(100.0%), 611.23 (33.5%), 612.24 (4.6%), 612.23 (2.4%). Anal calc for
(C28H31FN8O7) C, 55.08, H, 5.12, N, 18.35. Found: C, 54.98, H, 5.11, N,
18.38.
(3S)-(3-Azido-tetrahydro-5-(3,4-dihydro-5-methyl-2,4-dioxopyrimidin-1(2
H)-yl)furan-2-yl)methyl 9-fluoro-3,7-dihydro-3-methyl-10-(4-methylpiperazin-
1-yl)-7-oxo-2H-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxylate (8): Yield: 55%;
1
m.p.: 130◦C; H NMR (DMSO-d6) δ ppm: 1.36 (s, 3H, CH3), 1.42 (s, 3H,
CH3 of pyrimidinyl ring), 2.13 (m, 1H, CH-N3), 3.25 (dd, 4H, 2CH2-), 3.63
(dd, 4H, 2CH2-), 4.12 (m, 1H, -CHCH3), 4.54 (d, 1H, CH of furyl ring),
4.88 (s, 2H, CH2), 5.31 (d, 1H, CH of CH2 of oxazino ring), 5.46 (d, 1H,
CH of CH2 of oxazino ring), 5.62 (t, 1H, CH of furyl ring), 5.64 (s, 2H,
CH2), 8.54 (s, 1H, CH of pyrimidinyl ring), 9.15 (s, 1H, NH of pyrimidinyl
ring, D2O exchangeable), 9.42 (s, 1H, C5-H), 9.66 (s, 1H, C2-H); m/z:
610.23 (100.0%), 611.23 (33.5%), 612.24 (4.6%), 612.23 (2.4%). Anal calc
for (C28H31FN8O7) C, 55.08, H, 5.12, N, 18.35. Found: C, 54.98, H, 5.11, N,
18.38.
General Procedure for the Synthesis of Compounds 9–12
To zidovudine (1.00 equiv.) in dichloromethane added sulfuryl chloride
(5.00 equiv.) and stirred at room temperature for 48 hours. After the
completion of reaction the dichloromethane and excess of sulfuryl chloride
were distilled off under reduced pressure. This was further treated with flu-
oroquinolones (1.00 equiv.) like norfloxacin, ciprofloxacin, lomefloxacin,

100
P. Senthilkumar et al.
gatifloxacin in dichloromethane and pyridine to yield the titled compounds
(9–12).
7-(4-((1-(4-azido-tetrahydro-5-(hydroxymethyl)furan-2-yl)-1,2,3,4-tetrahy-
dro-2,4-dioxopyrimidin-5-yl)methyl)piperazine-1-yl)-1-ethyl-6-fluoro-1,-4-
1
dihydro-4-oxoquinoline-3-carboxylic acid (9): Yield: 50%; m.p.: 163◦C; H
NMR (DMSO-d6) δ ppm: 1.13 (t, 3H, CH2CH3), 3.4 (s, 2H, CH2), 2.13
(m, 1H, CH-N3), 3.15 (d, 2H, CH2CH3), 3.22 (dd, 4H, 2CH2-), 3.58 (dd,
4H, 2CH2-), 4.62 (s, 1H, OH), 5.62 (t, 1H, CH of furyl ring), 3.94 (s, 2H,
CH2), 6.54 (d, 1H, CH, -O-CH-O- of furyl ring), 8.34 (s, 1H, C8-H), 8.54
(s, 1H, CH of pyrimidinyl ring), 9.00 (s, 1H, NH of pyrimidinyl ring, D2O
exchangeable), 9.32 (s, 1H, C5-H), 9.56 (s, 1H, C2-H), 14.4 (1H, COOH);
m/z: 584.21 (100.0%), 585.22 (28.7%), 586.22 (5.4%), 585.21 (3.0%). Anal
calc for (C26H29FN8O7) C, 53.42, H, 5.00, N, 19.17. Found: C, 53.52, H,
4.99, N, 19.18.
7-(4-((1-(4-azido-tetrahydro-5-(hydroxymethyl)furan-2-yl)-1,2,3,4-tetrahy-
dro-2,4-dioxopyrimidin-5-yl)methyl)piperazine-1-yl)-1-cyclopropyl-6-fluoro-
1,4-dihydro-4-oxoquinoline-3-carboxylic acid (10): Yield: 40%; m.p.: 178◦C;
1H NMR (DMSO-d6) δ ppm: : 0.28–0.52 (m, 4H, cyclopropyl), 1.38 (m, 1H,
cyclopropyl), 3.4 (s, 2H, CH2), 2.13 (m, 1H, CH-N3), 3.22 (dd, 4H, 2CH2-),
3.58 (dd, 4H, 2CH2-), 4.62 (s, 1H, OH), 5.62 (t, 1H, CH of furyl ring),
3.94 (s, 2H, CH2), 6.54 (d, 1H, CH, -O-CH-O- of furyl ring), 8.34 (s, 1H,
C8-H), 8.54 (s, 1H, CH of pyrimidinyl ring), 9.00 (s, 1H, NH of pyrimidinyl
ring, D2O exchangeable), 9.32 (s, 1H, C5-H), 9.56 (s, 1H, C2-H), 14.4 (1H,
COOH); m/z: 596.21 (100.0%), 597.22 (29.8%), 598.22 (5.7%), 597.21
(3.0%). Anal calc for (C27H29FN8O7) C, 54.36, H, 4.90, N, 18.78. Found: C,
54.32, H, 4.91, N, 18.78.
7-(4-((1-(4-azido-tetrahydro-5-(hydroxymethyl)furan-2-yl)-1,2,3,4-tetrahy-
dro-2,4-dioxopyrimidin-5-yl)methyl)-3-methylpiperazine-1-yl)-1-ethyl-6,8-dif-
luoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (11): Yield: 54%; m.p.:
167◦C; 1H NMR (DMSO-d6) δ ppm: 1.09 (d, 3H, CH3), 1.13 (t, 3H,
CH2CH3), 3.4 (s, 2H, CH2), 2.13 (m, 1H, CH-N3), 3.15 (d, 2H, CH2CH3),
3.22 (dd, 2H, CH2-), 3.35 (m, 1H, CH2-), 3.58 (dd, 4H, 2CH2-), 4.62 (s,
1H, OH), 5.62 (t, 1H, CH of furyl ring), 3.94 (s, 2H, CH2), 6.54 (d, 1H,
CH, -O-CH-O- of furyl ring), 8.54 (s, 1H, CH of pyrimidinyl ring), 9.00 (s,
1H, NH of pyrimidinyl ring, D2O exchangeable), 9.32 (s, 1H, C5-H), 9.56
(s, 1H, C2-H), 14.4 (1H, COOH); m/z: 616.22 (100.0%), 617.22 (32.4%),
618.23 (4.3%), 618.22 (2.3%). Anal calc for (C27H30F2N8O7) C, 52.60, H,
4.90, N, 18.17. Found: C, 52.50, H, 4.90, N, 18.18.
7-(4-((1-(4-azido-tetrahydro-5-(hydroxymethyl)furan-2-yl)-1,2,3,4-tetrahy-
dro-2,4-dioxopyrimidin-5-yl)methyl)-3-methylpiperazine-1-yl)-1-cyclopropyl
-6-fluoro-1,4-dihydro-8-methoxy-4-oxoquinoline-3-carboxylic acid (12):
1
Yield: 46%; m.p.: 173◦C; H NMR (DMSO-d6) δ ppm: : 0.28–0.52 (m, 4H,
cyclopropyl), 1.09 (d, 3H, CH3), 1.38 (m, 1H, cyclopropyl), 3.4 (s, 3H,

Synthesis of Zidovudine Derivatives
101
-OCH3), 3.15 (s, 2H, CH2), 2.13 (m, 1H, CH-N3), 3.22 (dd, 2H, CH2-),
3.35 (m, 1H, CH2-), 3.58 (dd, 4H, 2CH2-), 4.62 (s, 1H, OH), 5.62 (t, 1H,
CH of furyl ring), 3.94 (s, 2H, CH2), 6.54 (d, 1H, CH, -O-CH-O- of furyl
ring), 8.54 (s, 1H, CH of pyrimidinyl ring), 9.00 (s, 1H, NH of pyrimidinyl
ring, D2O exchangeable), 9.32 (s, 1H, C5-H), 9.56 (s, 1H, C2-H), 14.4 (1H,
COOH); m/z: 640.24 (100.0%), 641.24 (34.6%), 642.25 (5.0%), 642.24
(2.6%), 643.25 (1.0%). Anal calc for (C29H33FN8O8) C, 54.37, H, 5.19, N,
17.49. Found: C, 54.32, H, 5.19, N, 17.48.
CONCLUSION
In the present study we identified that zidovudine ester derivative (5)
was found to show twenty two times more anti-HIV-1 activity to parent
compound. Many compounds inhibited HIV- 1 replication, M. tuberculosis,
and pathogenic bacteria. Thus these derivatives would be beneficial for the
effective treatment of HIV/AIDS. This is another milestone in continuation
to our dual-acting hybrid molecular approach.
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