Design, synthesis and in vitro antimalarial evaluation of triazole-linked chalcone and dienone hybrid compounds

Article abstract of DOI:10.1016/j.bmc.2010.10.009

A targeted series of chalcone and dienone hybrid compounds containing aminoquinoline and nucleoside templates was synthesized and evaluated for in vitro antimalarial activity. The Cu(I)-catalyzed cycloaddition of azides and terminal alkynes was applied as

Full text of DOI:10.1016/j.bmc.2010.10.009

Bioorganic & Medicinal Chemistry 18 (2010) 8243–8256
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Design, synthesis and in vitro antimalarial evaluation of triazole-linked
chalcone and dienone hybrid compounds
Eric M. Guantai a, Kanyile Ncokazi a, Timothy J. Egan a, Jiri Gut b, Philip J. Rosenthal b, Peter J. Smith c,
Kelly Chibale a,d,
⇑
a Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
b Department of Medicine, San Francisco General Hospital, University of California, San Francisco, CA 94143, USA
c Division of Pharmacology, University of Cape Town, Observatory 7925, South Africa
d Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
a r t i c l e i n f o
a b s t r a c t
Article history:
A targeted series of chalcone and dienone hybrid compounds containing aminoquinoline and nucleoside
templates was synthesized and evaluated for in vitro antimalarial activity. The Cu(I)-catalyzed
cycloaddition of azides and terminal alkynes was applied as the hybridization strategy. Several
chalcone-chloroquinoline hybrid compounds were found to be notably active, with compound 8b the
most active, exhibiting submicromolar IC50 values against the D10, Dd2 and W2 strains of Plasmodium
falciparum.
Received 7 August 2010
Revised 27 September 2010
Accepted 5 October 2010
Available online 31 October 2010
Keywords:
Malaria
Ó 2010 Elsevier Ltd. All rights reserved.
Chalcones
Dienones
Triazole
Hybrid compounds
Plasmodium falciparum
Aminoquinolines
Nucleosides
1. Introduction
With increasing resistance to available agents, intensive drug
discovery efforts aimed at developing new antimalarial drugs or
Malaria remains one of the most widespread infectious
diseases, and poses a great challenge to world health. This is under-
lined by staggering annual infection and mortality statistics.
Estimates range from 300 to 500 million clinical cases of malaria
each year, 90% of them in sub-Saharan Africa. The majority of these
cases are caused by P. falciparum,1,2 and result in about 1 million
deaths annually, mostly in children under 5 years of age.2,3
Resistance of malaria parasites to available antimalarial drugs
remains a main challenge to the effective control of the disease.
Varying levels of resistance to available classes of antimalarials
has been reported for P. falciparum, the predominant Plasmodium
species in Africa and the most virulent of them.1,4 This has led to
the adoption of combination therapies for the routine treatment
of uncomplicated malaria, with particular emphasis on artemisi-
nin-based combination therapies (ACTs).5–7 However, recent
evidence of diminished activity of artemisinins in Southeast Asia
threatens this strategy.8,9
modifying existing agents are ongoing. Ideally, highly efficacious,
novel antimalarial compounds will be developed to supplement
available drugs.
Molecular hybridization as a drug discovery strategy involves
the rational design of new chemical entities by the fusion (usually
via a covalent linker) of two drugs, both active compounds and/or
pharmacophoric units recognized and derived from known bioac-
tive molecules.10,11 The selection of the two principles in the dual
drug is usually based on their observed (or anticipated) synergistic
or additive pharmacological activities to enable the identification
of highly active novel chemical entities. In the context of attempt-
ing to circumvent antimalarial drug resistance, hybridization is
quite an attractive strategy, particularly when the pharmaco-
phores/active molecules being merged possess independent modes
of antimalarial action.
Another basis for hybridization is to exploit active transport
mechanisms by linking bioactive units to moieties that are recog-
nized and actively transported into mammalian cells, such as
amino acids12 and nucleosides.13
One of the potential disadvantages of molecular hybridization as
a drug discovery strategy is the obvious possibility of transferring
⇑
Corresponding author. Tel.: +27 21 650 2553; fax: +27 21 689 7499.
E-mail address: Kelly.Chibale@uct.ac.za (K. Chibale).
0968-0896/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2010.10.009

8244
E. M. Guantai et al. / Bioorg. Med. Chem. 18 (2010) 8243–8256
negative traits of any one of the hybrid components onto the target
dual drugs. For example, the incorporation of the 7-chloroquinoline
moiety could potentially result in cross-resistance, whereby hybrid
compounds containing this sub-structure exhibit similar suscepti-
bility patterns to chloroquine, specifically the reduced activity
against chloroquine resistant strains of the malarial parasite. How-
ever, despite such potential liabilities, promising hybridization
strategies need not be dismissed offhand as non-viable without pre-
liminary experimental data confirming the existence of suspected
shortcomings.
Although there are no examples of antimalarial dual drugs in
clinical use, a number of active molecules have been identified
using this approach. Highly active trioxaquines have been devel-
oped by covalently linking a 1,2,4-trioxane motif (derived from
the highly active natural sesquiterpene artemisinin) to a 4-amino-
quinoline moiety (borrowed from chloroquine and other amino-
quinoline-based antimalarials) via an appropriate spacer.14
Several chalcone-chloroquinoline hybrid compounds that showed
inhibition of b-hematin formation comparable with that exhibited
by chloroquine have also been identified.15 These examples and
others illustrate the potential of molecular hybridization as a strat-
egy for the development of novel antimalarial agents.
We therefore sought to apply this approach in the design of
hybrid compounds consisting of curcumin-related compounds
linked to other rationally selected entities via a triazole linker. This
hybridization strategy was to be facilitated by the robust and
experimentally simple cycloaddition of azides and terminal
alkynes to yield 1,2,3-triazoles.16–20 This Cu(I)-catalyzed reaction
has had wide application not just in mainstream organic chemis-
try, but also in medicinal chemistry/drug discovery for the synthe-
sis of bioactive molecules and generation of libraries of drug-like
scaffolds possessing the triazole ring.21,22
Chalcones and dienones are structurally related compounds.
Chalcones can be readily synthesized, and both naturally occurring
and synthetic chalcones have been shown to exhibit notable
in vivo and in vitro antimalarial activity.23–26 This has been
proposed to be by the inhibition of either plasmodial aspartate
proteases,27 cysteine proteases28 or new permeability pathways
introduced into erythrocyte cell membranes by the malaria para-
site.29 However, no reports on the investigation of the potential
antimalarial activity of dienones could be found in the literature.
AZT (Fig. 1), an antiretroviral agent approved for use in HIV
infection, was selected as one of the entities for hybridization to
the chalcones and dienones for several reasons. Firstly, AZT is
relatively hydrophilic,30 and the resulting hybrids would therefore
have enhanced aqueous solubilities and possibly improved oral
bioavailability. Secondly, AZT is a nucleoside (deoxythymidine)
analogue; nucleosides are biological molecules that are known to
be actively transported into mammalian cells,13 and therefore we
hypothesized that linking AZT to the chalcones or dienones (7, 9
and 13, Fig. 1) could improve oral bioavailability and facilitate
delivery to intracellular sites of action. Furthermore, hybridization
of the potentially antimalarial chalcones and dienones to a mole-
cule with intrinsic anti-HIV activity might lead to the identification
of molecules that exhibit both antimalarial and anti-HIV activity.
This is particularly interesting considering that in sub-Saharan
Africa, the high burden of both malaria and HIV translates into high
incidences of co-infection in many regions.31 Synergism between
antiretrovirals and established antimalarial drugs has also been
reported.32 Finally, AZT bears an azide functionality that could be
conveniently exploited in its hybridization to other entities via
click chemistry.
The 7-chloroquinoline moiety (Fig. 1), a pharmacophore present
in several established antimalarials such as chloroquine and
O
O
O
MeO
O
MeO
O
OMe
O
R
R
R
A
N
8a-c
7a-c
N
N
N
9a-e
N
N
N
N
N
O
O
O
N
O
OH
O
N
O
OH
O
N
Cl
HN
HN
O
O
MeO
OMe
O
MeO
R
R
R
O
O
14a-f
13a-f
N
N
N
N
N
10a-e
N
N
N
N
O
O
N
OH
Cl
N
N
Cl
HN
B
O
O
NH
HO
N
O
O
N
Cl
7-chloro-quinoline (4-substituted)
Figure 1. (A) General structures of the target chalcone and dienone hybrid compounds; (B) structures of AZT and 4-(substituted)-7-chloroquinoline.
N
3
AZT

E. M. Guantai et al. / Bioorg. Med. Chem. 18 (2010) 8243–8256
8245
amodiaquine, is thought to confer antimalarial potency to these
compounds by facilitating binding to heme and consequently
inhibiting hemozoin formation.33 This study aimed at exploiting
this feature by incorporating the 7-chloroquinoline moiety into
hybrid molecules with chalcones and dienones (8, 10 and 14,
Fig. 1).
group, and as such was ready for hybridization to the acetylenic
entities. 4-Azido-7-chloro-quinoline 6 was furnished by applying
the (modified) method described by de Souza et al.,37 whereby
4,7-dichloroquinoline was reacted with 2 equiv of NaN3 in anhy-
drous DMF at 65 °C for 6 h. Crystallization of the product from
CH2Cl2/hexane mixtures afforded 6 in 86% yield (Scheme 2).
The target chalcone hybrid compound series 7–10 were then ac-
cessed using the (modified) procedure reported by Fokin et al.20
Equimolar amounts of AZT or 6 and the relevant acetylenic com-
pound from series 1 or 2 were dissolved in DMF, after which 1 M
sodium ascorbate (0.4 equiv) and 1 M CuSO4 (20 mol %) were
added sequentially, in that order (Scheme 3). The reaction mixture
was then stirred vigorously at 65 °C for 24 h. Purification was by
silica gel column chromatography.
The relatively low yields associated with the synthesis of the
acetylenic dienones 5a–f prompted a slightly different approach to
the synthesis of the target dienone hybrid compounds (Scheme 4);
these were synthesized by initially reacting acetylenic enone
intermediate 4 with either AZT or 6 to generate the enone-triazole
derivatives 11 and 12 in good yield. These intermediates were
subsequently condensed with the appropriate benzaldehydes using
boron–trifluoride etherate as catalyst as already described above to
yield the target dienone hybrid derivatives 13a–f and 14a–f.
The synthesis and biological evaluation of the target hybrid
compounds is reported and discussed herein.
2. Synthesis
The synthesis of the target triazole hybrid compounds involved
the initial synthesis of the required precursors, that is, the acety-
lenic chalcones (1a–c, 2a–e) and acetylenic dienones (5a–f), as
well as 4-azido-7-chloroquinoline 6. The synthesis and character-
ization of series 1 and 2 was carried out previously by our group
and has already been reported.34 The dienones selected for synthe-
sis were to bear similar substitution patterns to these acetylenic
chalcones.
The synthesis of the acetylenic dienones was a 3-step process as
depicted in Scheme 1. The first step was an O-alkylation reaction,
involving the reaction of vanillin with 1.5 equiv of propargyl bro-
mide in anhydrous DMF in the presence of 1.5 equiv of anhydrous
K2CO3. This reaction yielded the acetylenic intermediate 3 in good
yield after purification by recrystallization from CH2Cl2/hexane
mixtures. The synthesis of intermediate 4 involved the base-cata-
lyzed Claisen–Schmidt condensation of 3 and acetone using the
(modified) method reported by Ramachandra and Subbaraju.35
Intermediate 3 was stirred in acetone (as reagent and solvent) in
the presence of aqueous 2.5 M NaOH at room temperature for
6 h. The crude product of the reaction was purified by silica gel
column chromatography to yield 4 in 84% yield.
In order to investigate the role of the a,b-unsaturated carbonyl
system of the enone intermediate 12, ‘control’ hybrid compounds
16 and 17 were also synthesized. Compound 16 was the
chloroquinoline triazole hybrid of phenoxyacetylene (15); 17 was
the equivalent hybrid of 3, an intermediate in the synthesis of
the acetylenic chalcones and dienones. The chemistry applied
was as described above for the other hybrid compounds (Scheme
5).
All compounds were characterized by 1H NMR, 13C NMR, Low
Resolution Mass Spectrometry, IR Spectroscopy, Elemental analysis
and melting point determination.
A final condensation of intermediate 4 and the appropriately
substituted benzaldehydes yielded the target acetylenic dienones
5a–e. This condensation was successfully carried out by modifying
a method reported for the synthesis of chalcones and which makes
3. In vitro antimalarial assay results and discussion
use of boron–trifluoride etherate (BF3–Et2O) as
a Lewis-acid
catalyst.36 This involved the reaction of 4 with 1.1 equiv of the
appropriate benzaldehyde in the presence of 1.5 equiv of BF3–
Et2O; the reaction was carried out in anhydrous dioxane under a
nitrogen atmosphere. The crude products were purified by silica
gel column chromatography (EtOAc/hexane) to yield the target
acetylenic dienone products in average yields.
Enantiomerically pure AZT (1-[(2R,4S,5S)-4-azido-5-(hydroxy-
methyl)oxolan-2-yl]-5-methyl-1,2,3,4-tetrahydro-pyrimidine-2,4-
dione) was applied for the hybridization. It already bears the azide
The target compounds were evaluated for their in vitro antima-
larial activity against the chloroquine sensitive (CQS) strain D10
and chloroquine resistant (CQR) strains Dd2 and W2 of P. falciparum.
Table 1 presents the in vitro antimalarial assay results for the
intermediates 1–6, 11 and 12, the hybrid target compounds 7–10
and 13–14 as well as the control hybrid compounds 16 and 17.
From Table 1 it can be seen that the target compounds generally
exhibited moderate in vitro antimalarial activity across all three
strains, with IC50 values generally falling in the lower micromolar
to high nanomolar range. The dienone hybrid series 13 and 14
were noticeably less active against W2, with several of them show-
ing no detectable antimalarial activity against this strain at the
O
O
MeO
highest concentration tested (IC50 >20 lM).
MeO
O
H
(i)
H
The acetylenic dienone series 5 showed in vitro antimalarial
activity comparable to the acetylenic chalcones, though some of
them showed negligible antimalarial activity against the D10 or
W2 strains. The most active acetylenic compound was 5c, the
tri-methoxylated acetylenic dienone, which had an IC50 value of
HO
Vanillin
3(82%)
H
0.9 and 1.4
lM against P. falciparum D10 and Dd2, respectively.
(ii)
Interestingly, the acetylenic enone intermediate 4 also showed
O
O
MeO
MeO
O
(iii)
R
O
Cl
N
N
N
3
5a-f
4 (71%)
(i)
H
H
Cl
Cl
Scheme 1. Reagents and conditions: (i) Propargyl bromide, K2CO3, DMF, 30 °C,
18 h; (ii) acetone, 2.5 M NaOH, rt, 6 h; (iii) appropriate benzaldehydes, BF3–Et2O,
dioxane, 50 °C, 16 h.
6
Scheme 2. Reagents and conditions: (i) NaN3, DMF, 65 °C, 6 h.

8246
E. M. Guantai et al. / Bioorg. Med. Chem. 18 (2010) 8243–8256
O
O
MeO
MeO
O
R
R
O
7a-c
N
8a-c
N
O
N
or
N
N
MeO
O
N
R
O
O
N
O
OH
N
Cl
1a-c
HN
H
(i)
O
O
O
OMe
O
OMe
O
OMe
O
R
R
R
N
N
or
2a-e
9a-e
N
10a-e
N
N
N
H
O
O
N
OH
Cl
N
HN
O
Scheme 3. Reagents and conditions: (i) AZT (for 7a–c and 9a–e) or 6 (for 8a–c and 10a–e), 1 M Na ascorbate, 1 M CuSO4ꢀ5H2O, DMF, 65 °C, 24 h.
O
O
MeO
MeO
O
O
MeO
O
O
11
12
N
4
(i)
N
N
or
N
N
N
H
O
O
N
O
OH
N
Cl
HN
(ii)
O
(ii)
O
MeO
O
MeO
R
R
O
14a-f
13a-f
N
N
N
N
N
N
O
O
N
O
OH
N
Cl
HN
Scheme 4. Reagents and conditions: (i) AZT (for 11) or 6 (for 12), 1 M Na ascorbate, 1 M CuSO4ꢀ5H2O, DMF, 65 °C, 24 h; (ii) appropriate benzaldehydes, BF3–Et2O, dioxane,
50 °C, 16 h.
moderate antimalarial activity, comparable to that of the acety-
lenic chalcones and dienones, with IC50s of 9.7 and 7.5 M against
P. falciparum D10 and Dd2, respectively. This would suggest that
for chalcones and dienones, the most basic structure/pharmaco-
phore required to exhibit antimalarial activity could be the
phenyl-propenone moiety.
the linking of the chalcones to AZT does not improve the in vitro
antimalarial activity of the acetylenic chalcones. The same could
be said for the dienone-AZT hybrid series 13, which were only
slightly more active than the acetylenic dienones 5, particularly
against D10 and Dd2.
Among the chalcone-chloroquinoline hybrid compounds (8 and
10), there were three compounds that were notably more potent;
submicromolar IC50 values were observed for 8b, 8c and 10b. Of
l
The activities of the chalcone-AZT hybrid series 7 and 9 were
comparable to that of the acetylenic chalcones, suggesting that

E. M. Guantai et al. / Bioorg. Med. Chem. 18 (2010) 8243–8256
8247
Table 1
In vitro antimalarial activities against the D10, Dd2 and W2 strains of P. falciparuma
(i)
(ii)
O
R0
D10 IC50
M)
Dd2 IC50
M)
W2 IC50
(lM)
16 (69%)
Compound
O
N
(
l
(
l
HO
15
N
40-OMe
20,40-diOMe
20,30,40-triOMe
2,4-diOMe
2,3,4-triOMe
2,4-diCl
4-F
9.7
3.4
7.7
>20
4.1
3.3
7.2
>20
9.7
11.8
5.4
0.9
9.2
9.8
11.9
>20
2.9
1.5
3.3
0.6
13.5
4.3
2.8
14.5
2.4
2.8
7.7
5.2
7.5
10.7
4.0
8.4
3.8
7.0
9.7
6.7
5.0
Phenol
1a
1b
1c
2a
2b
2c
2d
2e
4
5a
5b
5c
5d
5e
5f
6
7a
7b
7c
8a
8b
8c
9a
9b
9c
9d
9e
10a
10b
10c
10d
10e
11
N
H
N
Cl
O
>20
9.4
>20
>20
18.9
9.2
>20
21.5
>20
>20
8.0
5.4
5.4
5.0
0.09
0.6
9.0
7.1
8.4
6.6
7.1
6.6
0.5
11.5
6.9
O
MeO
O
O
2,4-diF
—
H
MeO
O
MeO
HO
H
(ii)
H
40-OMe
20,40-diOMe
20,30,40-triOMe
2,4-diCl
4-F
(i)
N
N
17 (84%)
3(82%)
1.4
9.0
Vanillin
N
H
6.5
9.3
>20
6.1
4.4
3.7
2.2
0.07
0.4
11.8
3.8
1.9
6.1
4.8
11.7
0.3
2,4-diF
—
N
Cl
40-OMe
20,40-diOMe
20,30,40-triOMe
40-OMe
20,40-diOMe
20,30,40-triOMe
2,4-diOMe
2,3,4-triOMe
2,4-diCl
4-F
Scheme 5. Reagents and conditions: (i) Propargyl bromide, K2CO3, DMF, 30 °C,
18 h; (ii) 6, 1 M Na ascorbate, 1 M CuSO4ꢀ5H2O, DMF, 65 °C, 24 h.
0.04
0.4
these three, compound 8b was the most active, having IC50 values
of 0.04, 0.07 and 0.09 lM against the D10, Dd2 and W2 strains of
10.2
5.4
3.7
7.3
3.9
5.2
0.3
P. falciparum, respectively. Notably, these three compounds were
either di- or tri-methoxylated chalcone-chloroquinoline hybrids;
none of the halogenated chalcone-chloroquinoline hybrid com-
pounds exhibited submicromolar IC50 values. The presence of the
chloroquinoline moiety on the three most active compounds is
most likely contributing to the improved activity that these
compounds exhibit; this is no surprise, since this sub-structure is
present in several established antimalarial drugs such as the
aminoquinolines chloroquine and amodiaquine. It is thought to
confer antimalarial potency to these compounds by facilitating
binding to intra-parasitic heme and consequently inhibiting hemo-
zoin formation.33 However, it was apparent that this significant
improvement in activity was not universal, as shown by the fact
that the other hybrid compounds in this class, as well as the corre-
sponding dienone-chloroquinoline hybrid compounds 14, did not
have similarly improved in vitro antimalarial activities.
2,4-diF
2,4-diOMe
2,3,4-triOMe
2,4-diCl
4-F
2,4-diF
—
6.0
1.9
1.6
2.1
16.4
0.7
7.4
4.1
12.0
0.8
10.6
ND
ND
12
—
13a
13b
13c
13d
13e
13f
14a
14b
14c
14d
14e
14f
16
40-OMe
20,40-diOMe
20,30,40-triOMe
2,4-diCl
4-F
2.8
1.3
1.3
1.4
1.7
1.4
3.0
5.1
2.5
19.0
9.4
10.2
>20
>20
>20
0.017
1.5
1.2
2.4
1.7
2.6
1.7
2.1
6.4
2.1
16.8
9.3
6.5
>20
>20
>20
0.097
18.2
14.5
8.3
9.1
ND
2,4-diF
12.4
5.3
40-OMe
20,40-diOMe
20,30,40-triOMe
2,4-diCl
4-F
>20
18.5
>20
>20
>20
ND
ND
>20
0.069
Also notable was that the enone-chloroquinoline triazole inter-
mediate 12 showed notably high in vitro antimalarial activity, with
submicromolar IC50 values against D10 and Dd2 P. falciparum; the
control chloroquinoline hybrid compounds 16 and 17 were inac-
tive against D10 and Dd2 P. falciparum at the highest concentration
2,4-diF
—
—
—
17
AZT
Chloroquine
—
tested (IC50 >20 lM). The AZT triazole intermediate 11 showed
moderate in vitro activity.
ND: Not determined.
a
Each compound was assayed in duplicate, on two separate occasions.
No obvious trends were observed as far as the influence of the
different substitution patterns of the chalcones or dienones on
antimalarial activity. The only consistent conclusion in this regard
is that none of the compounds with submicromolar IC50 values
were halogenated.
b-hematin, the synthetic equivalent of hemozoin. This particular
assay was applied for the chalcone-chloroquinoline hybrid target
molecules, and the IC50 values reported from this assay represent
the number of molar equivalents of the test compound, relative
to hematin, that are required to inhibit its conversion to b-hematin
by 50%—the lower the IC50, the more potent the compound is at
inhibiting b-hematin formation.
The results from the b-hematin inhibition assays of some of the
chalcone-chloroquinoline hybrid target molecules are shown in
Table 2. With the exception of 10a which was inactive at the high-
est concentration tested, the submitted compounds showed inhibi-
tion of b-hematin formation to varying degrees. The most potent
compound was 8c, with an IC50 of 0.2 equiv. Interestingly the
acetylenic chalcone 1b was also a more potent inhibitor of b-hema-
tin formation than chloroquine, with an IC50 value of 0.5 equiv.
Compound 8b, the most potent compound in vitro, was only
slightly more potent (IC50 1.6 equiv) than chloroquine, as was
4. b-Hematin inhibition assay results and discussion
As alluded to earlier, the inhibition of hemozoin formation is
one of the known mechanisms of antimalarial action, and quino-
line-based antimalarials such as chloroquine and amodiaquine
are proposed to exert their antimalarial activity via this mecha-
nism.38–40 On the strength of this, the chalcone-chloroquinoline
hybrid compounds were investigated for their potential to inhibit
hemozoin formation.
Assays have been designed to estimate the ability of compounds
to inhibit hemozoin formation.40 The assay described by Ncokazi
and Egan41 is one such assay, which colorimetrically quantifies
the ability of a compound to inhibit the conversion of hematin to

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E. M. Guantai et al. / Bioorg. Med. Chem. 18 (2010) 8243–8256
Table 2
availability of these compounds, may only become apparent
through pharmacokinetic profiling or in vivo antimalarial assays.
The chloroquinoline-hybridization strategy led to the identifica-
tion of highly active hybrid compounds, that is, 8b, 8c and 10b, as
well as the enone-chloroquinoline intermediate 12. Compound 8b
was the most active of these, with submicromolar IC50 values
against all three tested P. falciparum strains.
Results from b-inhibition assay of selected chalcone-chloroquinoline hybrid
compounds
Compound
R
b-Hematin inhibition (IC50 in equiv)a
1b
8b
8c
10a
10b
10d
20,40-diOMe
20,40-diOMe
20,30,40-triOMe
2,4-diOMe
2,3,4-triOMe
4-F
0.5
1.6
0.2
Inactive
4.1
Interestingly, both the chalcone-chloroquinoline hybrid com-
pounds 8 and their dienone counterparts 14 can be considered as
4.8
derivatives of intermediate 12 via modifications on its
a-carbon.
10e
Chloroquine
2,4-diF
—
1.6
1.91
It is also intriguing to note that hybridization to chloroquinoline
did not lead to a similarly potent activity in all these compounds;
instead, only the three methoxylated chalcones mentioned previ-
ously had notably improved activity. This indicates that the group
a
The IC50
s are averages of triplicate determinations and are reported in
equivalents of the drug relative to hematin.
on the terminal a-carbon of 12 is likely to be crucial for the reten-
tion of activity, and some groups could actually negate any benefi-
cial effects that the chloroquinoline moiety confers (as is the case
with the halogenated chalcone-chloroquinoline and the dienone-
chloroquinoline hybrid compounds).
Also noteworthy is the lack of activity of the control hybrid
compounds 16 and 17, both of which are structurally similar to
10e with a similar IC50. Compounds 10b and 10d were less potent
inhibitors of b-hematin formation than chloroquine. Though the
chalcone component of the hybrid compounds could contribute
to their potency as inhibitors of b-hematin formation (the chalcone
1b was a potent b-hematin inhibitor, for example), no obvious
structural features could be identified that could account for why
some of the hybrid compounds were significantly more potent
b-hematin inhibitors than others.
12 but don’t possess the
a,b-unsaturated carbonyl system. This
would point to the importance of the
a,b-unsaturated carbonyl
system of 12 on its in vitro antimalarial activity.
There was also no consistent correlation between b-hematin
inhibition and in vitro antimalarial potency for this set of com-
pounds, as the more potent inhibitors of b-hematin formation were
not necessarily the more potent compounds in vitro. This implies
the possible influence of other factors; one such factor could be
the degree of accumulation within the parasite digestive vacuole,
which is the definitive site of hemoglobin catabolism and therefore
the site of action of hemozoin inhibitors. Chloroquine accumulates
considerably within the parasite digestive vacuole by both satura-
ble42,43 and non-saturable (pH-dependent)33,44,45 mechanisms, a
factor that undoubtedly contributes to its antimalarial potency.
The lower in vitro antimalarial activity (relative to chloroquine)
of those target compounds showing comparable or superior
b-hematin inhibition could therefore suggest the absence of equiv-
alent accumulation mechanisms, resulting in lower concentrations
at the site of action (digestive vacuole) and ultimately in relatively
lower in vitro antimalarial efficacies. The target compounds were
notably not as basic as the dibasic chloroquine, which would lessen
the possibility of pH-dependent accumulation as a mechanism of
accumulation for these compounds.
The relatively lower activities of 13 and 14 against the CQR W2
P. falciparum (relative to the CQS D10 strain) may be interpreted as
evidence of cross-resistance, though such an interpretation is
somewhat blurred by the fact that the activities of these com-
pounds against the CQS D10 and the CQR Dd2 strains appear to
be comparable. This, along with the fact that the assay materials
and techniques applied for all three strains were similar, suggests
a lower intrinsic susceptibility of the W2 strain to these com-
pounds, rather than the presence of overt cross-resistance.
The fact that some of the compounds were quite potent inhibi-
tors of b-hematin formation (in several cases more active than
chloroquine) would suggest that this is a primary mechanism by
which these compounds exert their antimalarial activity, though
the presence of other mechanisms of action is also quite possible.
In conclusion, chalcone and dienone hybrid compounds were
successfully synthesized and tested for their in vitro antimalarial
activity, and the chalcone chloroquinoline hybrid compound 8b
was the most promising compound identified from the study.
In anticipation of subsequent in vivo and pharmacokinetic pro-
filing, compound 8b was evaluated for its cytotoxicity against the
Chinese Hamster Ovarian (mammalian) cell line. No cytotoxicity
was observed at the highest concentration tested (100 lM).
5. Discussion and conclusion
6. Experimental data
The moderate in vitro antimalarial activity observed for the
acetylenic chalcones 1 and 2 is in line with the published results
for alkoxylated chalcones, which have been reported as having IC50
values in the high nanomolar to low micromolar range;23,24 this
activity does not seem to be compromised by the presence of the
acetylene substitution. Acetylenic dienones exhibit comparable
antimalarial activity to the acetylenic chalcones. This is probably
attributable to the presence of the common phenyl propenone
sub-structure in both these series of compounds, as the acetylenic
enone intermediate 4 also exhibits comparable in vitro antimalarial
activity.
The AZT hybrid compounds of both the chalcones and dienones
did not exhibit notably higher in vitro antimalarial activity relative
to their acetylenic precursors, though the retention of activity in
most cases is still noteworthy as AZT itself showed negligible
in vitro antimalarial activity. It is therefore possible that the envis-
aged benefits of the AZT hybridization strategy, which were
primarily the increased solubility and possibly enhanced oral bio-
To guide in the interpretation of the 1H NMR data presented be-
low, the complete (and numbered) structures of all the intermedi-
ates and target compounds can be found in the Supplementary
data.
6.1. 3-Methoxy-4-prop-2-ynyloxy-benzaldehyde (3)
Vanillin (4-hydroxy-3-methoxybenzaldehyde) (13 mmol) was
dissolved in 10 mL of anhydrous DMF. Anhydrous K2CO3 (2.7 g,
19.5 mmol) was then added to the solution, and the mixture stirred
at 30 °C for 30 min. Propargyl bromide (3-bromopropyne, 2.2 mL,
19.5 mmol) was then added slowly to the reaction mixture, which
was subsequently stirred at 30 °C for 6 h upon which TLC indicated
completion of the reaction.
The reaction mixture was then diluted with 50 ml water and
extracted with ethyl acetate (3 ꢁ 50 mL). These extracts were then

E. M. Guantai et al. / Bioorg. Med. Chem. 18 (2010) 8243–8256
8249
combined, washed with water (2 ꢁ 50 mL), dried over anhydrous
6.3.2. 1-(2,4-Dimethoxy-phenyl)-5-(3-methoxy-4-prop-2-
ynyloxy-phenyl)-penta-1,4-dien-3-one (5b)
Na2SO4 and evaporated in vacuo to yield the product residue that
was then recrystallized from CH2Cl2/Hexane mixtures to yield
the pure 3 in 82% yield. Mp 86 °C (from CH2Cl2/Hex); Rf (EtOAc/
CH2Cl2/Hex) 0.43; IR mmax (CHCl3)/cmꢂ1 3307 (Alkynyl C–H),
3021 (Ar C–H), 2127 (C@C), 1683 (C@O), 1590 (Ar C@C); dH
(300 MHz, CDCl3) 9.87 (1H, s, H-7), 7.45 (1H, dd, J 1.9 and 7.8,
H-2), 7.43 (1H, d, J 1.9, H-1), 7.14 (1H, d, J 7.8, H-3), 4.85 (2H, d,
J 2.4, H-5), 3.94 (3H, s, H-4), 2.55 (1H, t, J 2.4, H-6); dC (75 MHz,
CDCl3) 190.8, 152.1, 150.1, 131.0, 126.1, 112.7, 109.6, 77.4, 76.6,
56.6, 56.0; LRMS (EI) m/z 191.3 (M+H) M+ C11H10O3 requires
190.1. Anal. Calcd for C11H10O3: C, 69.5; H, 5.3. Found: C, 69.5;
H 5.2.
Yellow solid (185 mg, 49%); mp 57–59 °C (from EtOAc/Hex); Rf
(EtOAc/Hex 4:6) 0.30; IR mmax (KBr)/cmꢂ1 3260 (Alkynyl C–H),
2927 (Ar C–H), 1642 (C@O), 1595 (Ar C@C); dH (300 MHz, CDCl3)
8.01 (1H, d, J 16.1, H-a0), 7.67 (1H, d, J 15.9, H-a), 7.55 (1H, d, J
8.6, H-30), 7.19 (1H, dd, J 1.9 and 8.3, H-2), 7.15 (1H, d, J 1.9, H-
1), 7.07 (1H, d, J 16.0, H-b0), 7.05 (1H, d, J 8.3, H-3), 6.98 (1H, d, J
15.8, H-b), 6.53 (1H, dd, J 2.3 and 8.6, H-20), 6.46 (1H, d, J 2.2, H-
10), 4.81 (2H, d, J 2.4 H-5), 3.94 (3H, s, H-40), 3.90 (3H, s, H-50),
3.85 (3H, s, H-4), 2.54 (1H, t, J 2.4, H-6); dC (75 MHz, CDCl3)
189.3, 163.0, 160.1, 149.8, 142.2, 138.5, 137.8, 130.4, 130.2,
129.4, 124.0, 122.2, 117.1, 113.9, 110.8, 105.5, 98.5, 77.4, 76.2,
56.7, 55.9, 55.5, 55.4; LRMS (EI) m/z 378.9 (M+H) M+ C23H22O5 re-
quires 378.2. Anal. Calcd for C23H22O5ꢀ½H2O: C, 71.2; H, 5.9. Found:
C, 71.5; H, 5.9.
6.2. 4-(3-Methoxy-4-prop-2-ynyloxy-phenyl)-but-3-en-2-one (4)
Compound (6.2 g, 32 mmol) 3 was dissolved in 30 mL acetone,
after which 2.5 M aqueous NaOH (19 mL, 48 mmol) was added.
The mixture was then stirred at room temperature for 6 h, after
which TLC showed complete consumption of the benzaldehyde
starting material. The reaction mixture was then gradually neutral-
ized with 2.5 M HCl, during which the crude product precipitated
out as an amorphous yellow solid. This crude product was then
filtered, washed with water, air dried and purified by silica column
chromatography (EtOAc/Hex) to yield a pale yellow, crystalline
solid (5.3 g, 71%); mp 103–105 °C (from EtOAc/Hex); Rf (EtOAc/
Hex 4:6) 0.33; IR mmax (KBr)/cmꢂ1 3253 (Alkynyl C–H), 2985 (Ar
C–H), 1671 (C@O), 1595 (Ar C@C); dH (400 MHz, CDCl3) 7.49 (1H,
d, J 16.2, H-a), 7.14 (1H, dd, J 2.0 and 8.3, H-2), 7.10 (1H, d, J 2.0,
H-1), 7.05 (1H, d, J 8.3, H-3), 6.63 (1H, d, J 16.2, H-b), 4.81 (2H, d,
J 2.4, H-5), 3.93 (3H, s, H-4), 2.43 (1H, t, J 2.4, H-6), 2.38 (3H, s,
H-b0); dC (100 MHz, CDCl3) 198.1, 149.9, 143.2, 128.6, 125.8,
122.4 (2C), 113.9, 110.4, 77.9, 76.2, 56.6, 55.9, 27.4; LRMS (EI)
m/z 231.3 (M+H) M+ C14H14O3 requires 230.1. Anal. Calcd for
6.3.3. 1-(3-Methoxy-4-prop-2-ynyloxy-phenyl)-5-(2,3,4-
trimethoxy-phenyl)-penta-1,4-dien-3-one (5c)
Yellow solid (191 mg, 47%); mp 67–69 °C (from EtOAc/Hex); Rf
(EtOAc/Hex 4:6) 0.33; IR mmax (KBr)/cmꢂ1 3260 (Alkynyl C–H),
2934 (Ar C–H), 1645 (C@O), 1588 (Ar C@C); dH (300 MHz, CDCl3)
7.94 (1H, d, J 16.1, H-a0), 7.67 (1H, d, J 15.9, H-a), 7.36 (1H, d, J
8.8, H-20), 7.20 (1H, dd, J 1.9 and 8.4, H-2), 7.15 (1H, d, J 1.9, H-
1), 7.06 (1H, d, J 16.1, H-b0), 7.04 (1H, d, J 8.3, H-3), 6.97 (1H, d, J
15.8, H-b), 6.71 (1H, d, J 8.8, H-10), 4.81 (2H, d, J 2.4 H-5), 3.95
(3H, s, H-30), 3.94 (3H, s, H-50), 3.91 (3H, s, H-40), 3.89 (3H, s, H-
4), 2.54 (1H, t, J 2.4, H-6); dC (100 MHz, CDCl3) 189.1, 155.7,
149.8, 148.9, 142.6, 138.1 (2C), 129.2, 124.9, 124.3, 123.5, 122.3,
121.9, 113.9, 110.7 (2C), 107.7, 78.0, 76.2, 61.5, 60.9, 56.7, 56.1,
55.9; LRMS (EI) m/z 409.4 (M+H) M+ C24H24O6 requires 408.2. Anal.
Calcd for C24H24O6ꢀ½H2O: C, 69.0; H, 6.0. Found: C, 69.5; H, 6.1.
6.3.4. 1-(2,4-Dichloro-phenyl)-5-(3-methoxy-4-prop-2-ynyloxy-
phenyl)-penta-1,4-dien-3-one (5d)
C14H14O3: C, 73.0; H, 6.1. Found: C, 72.8; H, 6.2.
Yellow solid (251 mg, 65%); mp 74–76 °C (from EtOAc/Hex); Rf
(EtOAc/Hex 4:6) 0.59; IR mmax (KBr)/cmꢂ1 3239 (Alkynyl C–H),
2949 (Ar C–H), 1653 (C@O), 1588 (Ar C@C); dH (300 MHz, CDCl3)
8.03 (1H, d, J 16.0, H-a0), 7.67 (1H, d, J 15.9, H-a), 7.64 (1H, d, J
8.5, H-30), 7.46 (1H, d, J 2.1, H-10), 7.29 (1H, dd, J 2.1 and 8.5, H-
20), 7.21 (1H, dd, J 2.0 and 8.4,, H-2), 7.14 (1H, d, J 2.0, H-1), 7.06
(1H, d, J 8.3, H-3), 7.04 (1H, d, J 16.0, H-b0), 6.96 (1H, d, J 15.9, H-
b), 4.82 (2H, d, J 2.4 H-5), 3.94 (3H, s, H-4), 2.54 (1H, t, J 2.4, H-
6); dC (75 MHz, CDCl3) 188.5, 150.2, 149.2, 143.8, 137.4, 136.3,
135.9, 131.9, 130.1, 128.8, 128.4, 128.2, 127.6, 123.7, 122.6,
113.9, 110.8, 77.9, 76.3, 56.7, 56.0; LRMS (EI) m/z 387.2 (M+H)
M+ C21H16Cl2O3 requires 386.1. Anal. Calcd for C21H16Cl2O3: C,
65.1; H, 4.2. Found: C, 64.8; H, 4.2.
6.3. General method A for the preparation of compounds 5a–f
A mixture of 230 mg (1 mmol) of 4 and the appropriately
substituted benzaldehyde (1.1 mmol) were dissolved in 10 mL
anhydrous 1,4-dioxane under a nitrogen atmosphere. To the
stirring mixture, BF3–Et2O (0.2 mL, 1.5 mmol) was added, and the
mixture stirred overnight at 50 °C. The reaction mixture was then
allowed to cool to ambient temperature, diluted with CH2Cl2 and
washed twice with water. The organic layer was then collected,
dried over anhydrous Na2SO4, concentrated in vacuo and the
product residue purified by silica column chromatography
(EtOAc/Hex).
6.3.5. 1-(4-Fluoro-phenyl)-5-(3-methoxy-4-prop-2-ynyloxy-
phenyl)-penta-1,4-dien-3-one (5e)
6.3.1. 1-(4-Methoxy-phenyl)-5-(3-methoxy-4-prop-2-ynyloxy-
phenyl)-penta-1,4-dien-3-one (5a)
Yellow solid (151 mg, 45%); mp 106–108 °C (from EtOAc/Hex);
Rf (EtOAc/Hex 4:6) 0.50; IR mmax (KBr)/cmꢂ1 3231 (Alkynyl C–H),
2920 (Ar C–H), 1667 (C@O), 1591 (Ar C@C); dH (300 MHz, CDCl3)
7.69 (1H, d, J 15.9, H-a0), 7.67 (1H, d, J 15.9, H-a), 7.61 (1H, d,
J 8.7, H-40), 7.60 (1H, d, J 8.7, H-10), 7.20 (1H, dd, J 1.9 ad 8.3, H-
2), 7.15 (1H, d, J 2.0, H-1), 7.13–7.04 (3H, m, H-20, 30, 3), 7.01 (1H,
d, J 16.3, H-b0), 6.93 (1H, d, J 15.9, H-b), 4.81 (2H, d, J 2.4 H-5),
3.93 (3H, s, H-4), 2.54 (1H, t, J 2.4, H-6); dC (75 MHz, CDCl3)
188.5, 165.7, 149.9, 149.1, 143.2, 141.7, 130.3, 130.1, 128.9,
125.0, 124.2, 122.6 (2C), 116.2, 115.9, 113.9, 110.7, 77.9, 76.2,
56.7, 55.9; LRMS (EI) m/z 336.9 (M+H) M+ C21H17FO3 requires
336.1. Anal. Calcd for C21H17FO3: C, 74.9; H, 5.1. Found: C, 74.5;
H, 5.1.
Yellow solid (135 mg, 39%); mp 124–125 °C (from EtOAc/Hex);
Rf (EtOAc/Hex 4:6) 0.30; IR mmax (KBr)/cmꢂ1 3289 (Alkynyl C–H),
3035 (Ar C–H), 1643 (C@O), 1599 (Ar C@C); dH (300 MHz, CDCl3)
7.70 (1H, d, J 16.0, H-a), 7.68 (1H, d, J 16.0, H-a0), 7.56 (2H, d, J
8.8, H-10, 40), 7.19 (1H, dd, J 2.0 and 8.3, H-2), 7.15 (1H, d, J 2.0,
H-1), 7.05 (1H, d, J 8.3, H-3), 6.97 (1H, d, J 16.0, H-b), 6.94 (1H, d,
J 16.0, H-b0), 6.92 (2H, d, J 8.8, H-20, 30), 4.81 (2H, d, J 2.4, H-5),
3.94 (3H, s, H-4), 3.85 (3H, s, H-40), 2.54 (1H, t, J 2.4, H-6); dC
(75 MHz, CDCl3) 188.7, 161.6, 149.9, 148.9, 142.8, 142.6, 130.1
(2C), 129.1, 127.6, 124.4, 123.3, 122.4, 114.4 (2C), 113.9, 110.7,
78.0, 76.2, 56.7, 55.9, 55.4; LRMS (EI) m/z 348.9 (M+H) M+
C22H20O4 requires 348.1. Anal. Calcd for C22H20O4: C, 75.8; H, 5.8.
Found: C, 75.7; H, 5.7.

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E. M. Guantai et al. / Bioorg. Med. Chem. 18 (2010) 8243–8256
6.3.6. 1-(2,4-Difluoro-phenyl)-5-(3-methoxy-4-prop-2-ynyloxy-
phenyl)-penta-1,4-dien-3-one (5f)
111.8, 110.3, 85.1, 84.6, 62.4, 61.5, 60.0, 56.4, 56.2, 37.9, 12.9;
LRMS (EI) m/z 590.5 (M+H) M+ C30H31N5O8 requires 589.2. Anal.
Calcd for C30H31N5O8ꢀH2O: C, 59.2; H, 5.4; N, 11.5. Found: C,
59.3; H, 5.4; N, 11.6.
Yellow solid (153 mg, 43%); mp 99–101 °C (from EtOAc/Hex); Rf
(EtOAc/Hex 4:6) 0.55; IR mmax (KBr)/cmꢂ1 3224 (Alkynyl C–H),
2992 (Ar C–H), 1645 (C@O), 1584 (Ar C@C); dH (300 MHz, CDCl3)
7.78 (1H, d, J 16.1, H-a0), 7.70 (1H, d, J 15.9, H-a), 7.62 (1H, d, J
8.5, H-30), 7.21 (1H, dd, J 2.0 ad 8.3, H-2), 7.16–7.12 (2H, m, H-b0,
1), 7.07 (1H, d, J 8.3, H-3), 6.95 (1H, d, J 15.9, H-b), 6.90 (1H, dd, J
2.4 and 8.6, H-20), 6.87 (1H, d, J 2.4, H-10), 4.83 (2H, d, J 2.4 H-5),
3.94 (3H, s, H-4), 2.55 (1H, t, J 2.4, H-6); dC (75 MHz, CDCl3)
188.5, 165.3, 160.7, 149.9, 149.0, 143.5, 134.5, 130.6, 128.9,
127.3, 124.1, 122.7, 113.9, 112.3, 112.0, 110.7, 104.9, 78.0, 76.3,
56.7, 56.0; LRMS (EI) m/z 355.0 (M+H) M+ C21H16F2O3 requires
354.1. Anal. Calcd for C21H16F2O3: C, 71.2; H, 4.6. Found: C, 70.8;
H, 5.0.
6.5.2. 1-[4-(4-{4-[3-(2,4-Dimethoxy-phenyl)-3-oxo-propenyl]-2-
methoxy-phenoxymethyl}-[1,2,3]triazol-1-yl)-5-
hydroxymethyl-tetrahydro-furan-2-yl]-5-methyl-1H-
pyrimidine-2,4-dione (7b)
Yellow solid (289.6 mg, 47%); mp: 133–134 °C (from MeOH/
EtOAc); Rf (EtOAc/Hex 9:1) 0.11; IR mmax (CHCl3)/cmꢂ1 3385 (O–
H), 3015 (Ar C–H), 1694 (C@O), 1602 (Ar C@C); dH (400 MHz,
DMSO-d6) 11.30 (1H, s, H-14), 8.41 (1H, s, H-6), 7.79 (1H, s, H-
12), 7.56 (1H, d, J .5, H-30), 7.47 (1H, d, J 15.8, H-a), 7.39 (1H, d, J
15.8, H-b), 7.31 (1H, d, J 1.9, H-1), 7.26 (1H, dd, J 1.9 and 8.3, H-
2), 7.20 (1H, d, J 8.3 H-3), 6.66 (1H, d, J 2.4, H-10), 6.62 (1H, dd, J
2.4 and 8.4, H-20), 6.42 (1H, t, J 6.6, H-9), 5.41–5.36 (1H, m, H-7),
5.25 (1H, s, H-15), 5.19 (2H, s, H-5), 4.24–4.21 (1H, m, H-10),
3.87 (3H, s, H-40), 3.83 (3H, s, H-50), 3.79 (3H, s, H-4), 3.71–3.60
(2H, m, H-11), 2.77–2.61 (2H, m, H-8), 1.80 (3H, s, H-13); dC
(100 MHz, DMSO-d6) 190.3, 164.3, 160.6, 151.1, 150.2, 149.9,
143.3, 142.5, 136.9, 132.4, 128.9, 126.0, 125.2, 123.0, 122.4,
114.1, 111.8, 110.3, 106.6, 99.4, 92.2, 85.0, 84.6, 65.5, 62.4, 61.5,
60.0, 56.6, 56.1, 37.9, 12.9; LRMS (EI) m/z 620.5 (M+H) M+
C31H33N5O9 requires 619.2. Anal. Calcd for C31H33N5O9ꢀ½H2O:
C, 59.2; H, 5.4; N, 11.1. Found: C, 59.0; H, 5.1; N, 10.6.
6.4. 4-Azido-7-chloro-quinoline (6)
4,7-Dichloroquinoline (2.0 g, 10 mmol) was dissolved in 5 mL
anhydrous DMF. NaN3 (1.3 g, 20 mmol) was then added in one por-
tion, and the resulting mixture stirred at 65 °C for 6 h, whereupon
TLC indicated reaction completion. The reaction mixture was then
allowed to cool to ambient temperature, after which it was diluted
with 100 mL CH2Cl2, washed with water (3 ꢁ 30 mL), dried over
anhydrous Na2SO4, and evaporated to dryness. The resulting prod-
uct residue was crystallised from a CH2Cl2/Hexane mixture to yield
the final pure product as colorless, needle-like crystals (1.7 g, 86%);
mp 115 °C (from CH2Cl2/Hex); Rf (EtOAc/Hex 3:7) 0.29; IR mmax
(CHCl3)/cmꢂ1 3021 (Ar C–H), 1612 (Ar C@C); dH (300 MHz, CDCl3)
8.83 (1H, d, J 4.9, H-2), 8.09 (1H, d, J 2.4, H-8), 8.01 (1H, d, J 9.3,
H-5), 7.49 (1H, dd, J 2.4 and 9.3, H-6) 7.13 (1H, d, J 4.9, H-3); dC
(100 MHz, CDCl3) 150.9, 149.1, 146.8, 136.9, 127.9, 123.8, 119.9,
108.7; LRMS (EI) m/z 204.9 (M+H) M+ C9H5ClN4 requires 204.0.
Anal. Calcd for C9H5ClN4: C, 52.8; H, 2.5; N, 27.4. Found: C, 52.8;
H, 2.4; N, 27.5.
6.5.3. 1-[5-Hydroxymethyl-4-(4-{2-methoxy-4-[3-oxo-3-(2,3,4-
trimethoxy-phenyl)-propenyl]-phenoxymethyl}-[1,2,3]triazol-
1-yl)-tetrahydro-furan-2-yl]-5-methyl-1H-pyrimidine-2,4-
dione (7c)
Yellow solid (299.1 mg, 46%); mp 103–105 °C (from MeOH/
EtOAc); Rf (EtOAc/Hex 9:1) 0.10; IR mmax (CHCl3)/cmꢂ1 3385 (O–
H), 3015 (Ar C–H), 1694 (C@O), 1593 (Ar C@C); dH (400 MHz,
DMSO-d6) 11.29 (1H, s, H-14), 8.42 (1H, s, H-6), 7.80 (1H, s, H-
12), 7.48 (1H, d, J 16.1, H-a), 7.32 (1H, d, J 16.1, H-b), 7.36–7.28
(3H, m, H-20, 1, 2), 7.22 (1H, d, J 8.3, H-3), 6.93 (1H, d, J 8.8, H-
10), 6.43 (1H, t, J 6.3, H-9), 5.43–5.37 (1H, m, H-7), 5.24 (1H, s, H-
15), 5.21 (2H, s, H-5), 4.27–4.23 (1H, m, H-10), 3.88 (3H, s, H-30),
3.84 (3H, s, H-50), 3.81 (3H, s, H-40), 3.80 (3H, s, H-4), 3.75–3.63
(2H, m, H-11), 2.81–2.62 (2H, m, H-8), 1.82 (3H, s, H-13); dC
(100 MHz, DMSO-d6) 191.3, 164.4, 157.0, 153.3, 151.1, 150.4,
149.9, 143.8, 143.3, 142.4, 136.9, 128.6, 127.3, 125.5, 125.2,
123.3, 114.1, 111.8, 110.2, 108.5, 92.1, 85.1, 84.6, 62.3, 61.5, 61.2,
60.4, 60.0, 56.8, 56.3, 37.9, 12.9; LRMS (EI) m/z 650.7 (M+H) M+
C32H35N5O10 requires 649.2. Anal. Calcd for C32H35N5O10ꢀ½H2O:
C, 58.3; H, 5.3; N, 10.6. Found: C, 58.2; H, 5.4; N, 10.8.
6.5. General method B for the preparation of compounds 7, 8, 9
and 10
The appropriate acetylenic chalcone 1 or 2 (1 mmol) and the
appropriate azide (6 or enantiomerically pure (2R,4S,5S) AZT,
1 mmol) were dissolved in 5 mL DMF and, while stirring at 65 °C,
1 M sodium ascorbate (0.4 mL, 0.4 mmol) and 1 M CuSO4 (0.2 mL,
20 mol %) were added sequentially, in that order. The reaction mix-
ture was then stirred at 65 °C for 24 h. The crude product was then
precipitated out by slowly adding cold water to the reaction mix-
ture, after which it was filtered, washed with water, air dried and
purified by silica column chromatography (eluents ranging in
polarity from EtOAc/Hex 3:7 to 5%MeOH in EtOAc).
6.5.4. 3-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-
ylmethoxy]-3-methoxy-phenyl}-1-(4-methoxy-phenyl)-
propenone (8a)
6.5.1. 1-[5-Hydroxymethyl-4-(4-{2-methoxy-4-[3-(4-methoxy-
phenyl)-3-oxo-propenyl]-phenoxymethyl}-[1,2,3]triazol-1-yl)-
tetrahydro-furan-2-yl]-5-methyl-1H-pyrimidine-2,4-dione (7a)
Yellow solid (294.4 mg, 50%); mp 121–122 °C (from MeOH/
EtOAc); Rf (EtOAc/Hex 9:1) 0.11; IR mmax (CHCl3)/cmꢂ1 3385 (O–
H), 3015 (Ar C–H), 1691 (C@O), 1599 (Ar C@C); dH (300 MHz,
DMSO-d6) 11.30 (1H, s, H-14), 8.41 (1H, s, H-6), 8.14 (2H, d, J 8.8,
H-10, 40), 7.81 (1H, d, J 15.6, H-a), 7.80 (1H, s, H-12), 7.65 (1H, d, J
15.6, H-b), 7.52 (1H, d, J 1.7, H-1), 7.38 (1H, dd, J 1.7 and 8.3, H-
2), 7.22 (1H, d, J 8.3, H-3), 7.07 (2H, d, J 8.9, H-20, 30), 6.42 (1H, t,
J 6.6, H-9), 5.42–5.37 (1H, m, H-7), 5.20 (2H, s, H-5), 4.25–4.22
(1H, m, H-10), 3.86 (3H, s, H-50), 3.84 (3H, s, H-4), 3.72–3.60 (2H,
m, H-11), 2.78–2.62 (2H, m, H-8), 1.8 (3H, s, H-13); dC (100 MHz,
DMSO-d6) 187.9, 164.4, 163.8, 151.1, 150.5, 149.9, 144.2, 143.3,
136.9, 131.5, 130.9, 128.9, 125.2, 124.1, 120.6, 114.6, 113.9,
Yellow solid (303.4 mg, 58%); mp 178–180 °C (from EtOAc); Rf
(EtOAc/Hex 6;4) 0.25; IR mmax (CHCl3)/cmꢂ1 3021 (Ar C–H), 1657
(C@O), 1599 (Ar C@C); dH (400 MHz, CDCl3) 9.06 (1H, d, J 4.8,
H-8), 8.27 (1H, d, J 2.0, H-9), 8.15 (1H, s, H-6), 8.01 (2H, d, J 9.0,
H-10, 40), 7.98 (1H, d, J 9.0, H-11), 7.74 (1H, d, J 15.6, H-a), 7.59
(1H, dd, J 2.0 and 8.9, H-10), 7.51 (1H, d, J 4.8, H-7), 7.42 (1H, d,
J 15.6, H-b), 7.23 (1H, d, J 1.8, H-1), 7.18–7.14 (2H, m, H-2, 3),
6.97 (2H, d, J 9.0, H-20, 30), 5.43 (2H, s, H-5), 3.94 (3H, s, H-50),
3.88 (3H, s, H-4); dC (100 MHz, CDCl3) 188.7, 163.3, 151.1, 149.8,
149.5, 144.8, 143.7, 141.1, 137.2, 131.2, 130.7, 129.6, 129.4,
128.8, 124.8, 124.5, 122.5, 120.6, 116.0, 114.1, 113.9, 111.1, 62.9,
56.1, 55.5; LRMS (EI) m/z 527.6 (M+H) M+ C29H23ClN4O4 requires
526.1. Anal. Calcd for C29H23ClN4O4ꢀ½H2O: C, 64.9; H, 4.5; N,
10.4. Found: C, 65.1; H, 4.5; N, 10.7.

E. M. Guantai et al. / Bioorg. Med. Chem. 18 (2010) 8243–8256
8251
6.5.5. 3-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-
ylmethoxy]-3-methoxy-phenyl}-1-(2,4-dimethoxy-phenyl)-
propenone (8b)
DMSO-d6) 11.28 (1H, s, H-14), 8.43 (1H, s, H-6), 7.87 (1H, d, J
15.6, H-a), 7.83 (1H, dd, J 2.0 and 8.6, H-3), 7.82 (1H, d, J 15.6,
H-b), 7.79 (1H, s, H-12), 7.76 (1H, d, J 8.9, H-10), 7.58 (1H, d, J 2.0,
H-1), 7.32 (1H, d, J 8.6, H-2), 6.91 (1H, d, J 8.9, H-20), 6.42 (1H, t, J
6.6, H-9), 5.42–5.37 (1H, m, H-7), 5.27 (2H, s, H-5), 5.24 (1H, s,
H-15), 4.25–4.22 (1H, m, H-10), 3.86 (3H, s, H-50), 3.85 (3H, s,
H-30), 3.83 (3H, s, H-4), 3.77 (3H, s, H-40), 3.76–3.63 (2H, m,
H-11), 2.77–2.62 (2H, m, H-8), 1.80 (3H, s, H-13); dC (75 MHz,
DMSO-d6) 187.4, 163.6, 155.5, 152.9, 151.6, 150.3, 148.9, 142.4,
141.8, 137.5, 136.1, 131.2, 124.5, 123.3, 122.7, 121.1, 120.4,
112.4, 111.0, 109.5, 108.4, 84.4, 83.9, 61.7, 61.4, 60.7, 60.4, 59.3,
56.0, 55.5, 37.1, 12.1; LRMS (EI) m/z 650.8 (M+H) M+
C32H35N5O10 requires 649.2. Anal. Calcd for C32H35N5O10ꢀ1H2O: C,
57.5; H, 5.5; N, 10.5. Found: C, 57.3; H, 5.4; N, 10.4.
Yellow solid (282.7 mg, 51%); mp: 122–124 °C (from EtOAc); Rf
(EtOAc/Hex 6:4) 0.12; IR mmax (CHCl3)/cmꢂ1 3020 (Ar C–H), 1653
(C@O), 1604 (Ar C@C); dH (400 MHz, CDCl3) 9.05 (1H, d, J 4.8, H-
8), 8.26 (1H, d, J 2.0, H-9), 8.13 (1H, s, H-6), 7.96 (1H, d, J 9.2, H-
11), 7.74 (1H, d, J 8.6, H-30), 7.60 (1H, d, J 15.6, H-a), 7.58 (1H,
dd, J 2.0 and 9.2, H-10), 7.49 (1H, d, J 4.6, H-7), 7.38 (1H, d, J
15.6, H-b), 7.20 (1H, dd, J 2.0 and 8.4, H-2), 7.14–7.12 (2H, m, H-
1, 3), 6.57 (1H, dd, J 2.2 and 8.6, H-20), 6.50 (1H, d, J 2.2, H-10),
5.48 (2H, s, H-5), 3.92 (3H, s, H-40), 3.90 (3H, s, H-50), 3.87 (3H, s,
H-4); dC (100 MHz, CDCl3) 190.5, 164.1, 160.2, 151.3, 150.2,
149.8, 149.2, 144.9, 141.9, 140.9, 137.0, 132.7, 129.8, 129.5,
129.0, 126.0, 124.8, 124.5, 122.4, 122.1, 120.6, 116.0, 114.2,
111.3, 105.2, 98.7, 63.0, 55.9, 55.9, 55.5; LRMS (EI) m/z 557.5
(M+H) M+ C30H25ClN4O5 requires 556.2. Anal. Calcd for
6.5.9. 1-[4-(4-{4-[3-(2,4-Dichloro-phenyl)-acryloyl]-2-methoxy-
phenoxymethyl}-[1,2,3]triazol-1-yl)-5-hydroxymethyl-tetra-
hydro-furan-2-yl]-5-methyl-1H-pyrimidine-2,4-dione (9c)
Yellow solid (279.3 mg, 45%); mp 112–114 °C (from MeOH/
C30H25ClN4O5: C, 64.7; H, 4.5; N, 10.1. Found: C, 64.9; H, 4.4; N,
10.0. HPLC.
EtOAc); Rf (EtOAc/Hex 8:2) 0.10; IR m
max (CHCl3)/cmꢂ1 3391 (O–H),
6.5.6. 3-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-
ylmethoxy]-3-methoxy-phenyl}-1-(2,3,4-trimethoxy-phenyl)-
propenone (8c)
3018 (Ar C–H), 1692 (C@O), 1582 (Ar C@C); dH (400 MHz, DMSO-
d6) 11.30 (1H, s, H-14), 8.43 (1H, s, H-6), 8.23 (1H, d, J 8.6, H-20),
8.02 (1H, d, J 15.6, H-a), 7.94–7.91 (2H, m, H-b, 3), 7.79 (1H, s, H-
12), 7.73 (1H, d, J 2.0, H-1), 7.61 (1H, d, J 2.0, H-10), 7.54 (1H, dd, J
2.0 and 8.6, H-30), 7.33 (1H, d, J 8.6, H-2), 6.42 (1H, t, J 6.6, H-9),
5.42–5.37 (1H, m, H-7), 5.28 (2H, s, H-5), 4.25–4.22 (1H, m, H-10),
3.83 (3H, s, H-4), 3.73–3.60 (2H, m, H-11), 2.77–2.61 (2H, m, H-8),
1.80 (3H, s, H-13); dC (75 MHz, DMSO) 187.0, 163.6, 152.2, 150.4,
149.0, 142.3, 136.5, 136.1, 135.3, 134.9, 131.5, 130.5, 129.8, 129.4,
127.8, 125.3, 124.5, 123.4, 112.4, 111.1, 109.6, 84.4, 83.9, 61.7,
60.7, 59.3, 55.6, 37.1, 12.1; LRMS (EI) m/z 628.6 (M+H) M+
C29H27Cl2N5O7 requires 627.1. Anal. Calcd for C29H27Cl2N5O7ꢀ½H2O:
C, 54.7; H, 4.2; N, 11.0. Found: C, 54.4; H, 4.8; N, 10.8.
Yellow solid (318.3 mg, 54%); mp: 124 °C (from EtOAc); Rf
(EtOAc/Hex 6:4) 0.20; IR mmax (CHCl3)/cmꢂ1 3015 (Ar C–H), 1649
(C@O), 1593 (Ar C@C); dH (300 MHz, CDCl3) 9.05 (1H, d, J 4.4, H-
8), 8.27 (1H, d, J 1.9, H-9), 8.14 (1H, s, H-6), 7.99 (1H, d, J 9.3, H-
11), 7.61 (1H, d, J 16.1, H-a), 7.59 (1H, dd, J 1.9 and 9.3, H-10),
7.50 (1H, d, J 4.4, H-7), 7.45 (1H, d, J 8.8, H-20), 7.37 (1H, d, J
16.1, H-b), 7.21 (1H, dd, J 1.9, 8.3, H-2), 7.16–7.12 (2H, m, H-1,
3), 6.75 (1H, d, J 8.8, H-10), 5.48 (2H, s, H-5), 3.92–3.90 (12H, m,
H-30, 50, 40, 4);dC (75 MHz, CDCl3) 190.8, 156.9, 151.1, 149.8,
149.4, 144.9, 142.9, 142.2, 137.2, 129.6, 129.5, 128.8, 126.9,
125.6, 125.3, 124.8, 124.6, 122.5, 116.0, 114.0, 111.0, 107.4, 62.9,
62.1, 61.1, 56.1, 56.0; LRMS (EI) m/z 587.4 (M+H) M+ C31H27ClN4O6
requires 586.2. Anal. Calcd for C31H27ClN4O6: C, 63.4; H, 4.6; N, 9.6.
Found: C, 63.2; H, 4.5; N, 9.5.
6.5.10. 1-[4-(4-{4-[3-(4-Fluoro-phenyl)-acryloyl]-2-methoxy-
phenoxymethyl}-[1,2,3]triazol-1-yl)-5-hydroxymethyl-tetra-
hydro-furan-2-yl]-5-methyl-1H-pyrimidine-2,4-dione (9d)
Yellow solid (278.1 mg, 48%); mp 130–132 °C (from MeOH/
6.5.7. 1-[4-(4-{4-[3-(2,4-Dimethoxy-phenyl)-acryloyl]-2-
methoxy-phenoxymethyl}-[1,2,3]triazol-1-yl)-5-
hydroxymethyl-tetrahydro-furan-2-yl]-5-methyl-1H-
pyrimidine-2,4-dione (9a)
EtOAc); Rf (EtOAc/Hex 9:1) 0.18; IR m
max (CHCl3)/cmꢂ1 3386 (O–H),
3018 (Ar C–H), 1689 (C@O), 1597 (Ar C@C); dH (300 MHz, DMSO-
d6) 11.28 (1H, s, H-14), 8.43 (1H, s, H-6), 7.85 (1H, d, J 15.6, H-a),
7.81 (1H, dd, J 1.9 and 8.8, H-3), 7.79 (1H, s, H-12), 7.78 (1H, d, J
15.6, H-b), 7.76 (2H, d, J 8.8, H-10, 40), 7.58 (1H, d, J 1.9, H-1), 7.31
(2H, d, J 8.8, H-20, 30), 6.89 (1H, d, J 8.8, H-2), 6.42 (1H, t, J 6.8, H-9),
5.43–5.36 (1H, m, H-7), 5.27 (2H, s, H-5), 4.26–4.22 (1H, m, H-10),
3.85 (3H, s, H-4), 3.70–3.59 (2H, m, H-11), 2.80–2.61 (2H, m, H-8),
1.80 (3H, s, H-13); dC (75 MHz, DMSO-d6) 187.4, 163.6, 155.5,
152.9, 151.6, 150.3, 148.9, 142.4, 137.5, 136.1, 131.2, 124.5, 123.3,
122.8, 121.1, 120.4, 112.4, 111.0, 109.5, 108.4, 84.4, 83.9, 61.7,
60.7, 59.3, 55.5, 37.1, 12.1; LRMS (EI) m/z 578.6 (M+H) M+
C29H28FN5O7 requires 577.2. Anal. Calcd for C29H28FN5O7: C, 60.3;
H, 4.9; N, 12.1. Found: C, 60.1; H, 5.5; N, 11.9.
Yellow solid (272.6 mg, 44%); mp 135–136 °C (from MeOH/
EtOAc); Rf (EtOAc/Hex 9:1) 0.15; IR mmax (CHCl3)/cmꢂ1 3021 (Ar
C–H), 1691 (C@O), 1599 (Ar C@C); dH (400 MHz, DMSO-d6) 8.43
(1H, s, H-6), 7.95 (1H, d, J 15.7, H-a), 7.90 (1H, d, J 8.6, H-20), 7.81
(1H, dd, J 1.8 and 8.6, H-3), 7.78 (2H, m, H-1, 12), 7.74 (1H, d, J
15.6, H-b), 7.57 (1H, d, J 2.0, H-10), 7.31 (1H, d, J 8.6, H-2), 6.61
(1H, dd, J 2.0 and 8.6, H-30), 6.61 (1H, t, J 6.6, H-9), 5.42–5.37
(1H, m, H-7), 5.26 (2H, s, H-5), 4.24–4.21 (1H, m, H-10), 3.89
(3H, s, H-50), 3.83 (6H, s, H-4, 40), 3.74–3.63 (2H, m, H-11), 2.77–
2.61 (2H, m, H-8), 1.79 (3H, s, H-13); dC (75 MHz, DMSO-d6)
187.4, 163.6, 162.9, 159.8, 151.5, 150.3, 148.9, 142.4, 137.8,
136.1, 131.3, 129.9, 124.5, 122.6, 119.0, 116.0, 112.4, 110.9,
109.5, 106.3, 98.2, 84.4, 83.9, 61.7, 60.7, 59.3, 55.8, 55.5, 55.4,
37.1, 12.1; LRMS (EI) m/z 620.6 (M+H) M+ C31H33N5O9 requires
619.2. Anal. Calcd for C31H33N5O9ꢀ½H2O: C, 59.2; H, 5.3; N, 11.1.
Found: C, 59.0; H, 5.5; N, 11.0.
6.5.11. 1-[4-(4-{4-[3-(2,4-Difluoro-phenyl)-acryloyl]-2-meth-
oxy-phenoxymethyl}-[1,2,3]triazol-1-yl)-5-hydroxymethyl-
tetrahydro-furan-2-yl]-5-methyl-1H-pyrimidine-2,4-dione (9e)
Yellow solid (248.9 mg, 44%); mp 128–130 °C (from MeOH/
EtOAc); Rf (EtOAc/Hex 9:1) 0.18; IR mmax (CHCl3)/cmꢂ1 3386 (O–
H), 3018 (Ar C–H), 1692 (C@O), 1600 (Ar C@C); dH (300 MHz,
DMSO-d6) 11.30 (1H, s, H-14), 8.44 (1H, s, H-6), 7.97 (1H, d, J
15.6, H-a), 7.90 (1H, d, J 8.3, H-20), 7.83–7.79 (2H, m, H-1, 3),
7.76 (1H, d, J 15.6, H-b), 7.59 (1H, d, J 1.9, H-10), 7.34 (1H, dd, J
1.9 and 8.3, H-30), 6.64 (1H, d, J 8.8, H-2), 6.44 (1H, t, J 6.3, H-9),
5.44–5.38 (1H, m, H-7), 5.28 (2H, s, H-5), 5.25 (1H, br s, H-15),
4.28–4.24 (1H, m, H-10), 3.85 (3H, s, H-4), 3.76–3.63 (2H, m, H-
11), 2.81–2.62 (2H, m, H-8), 1.82 (3H, s, H-13); dC (75 MHz,
6.5.8. 1-[5-Hydroxymethyl-4-(4-{2-methoxy-4-[3-(2,3,4-
trimethoxy-phenyl)-acryloyl]-phenoxymethyl}-[1,2,3]triazol-1-
yl)-tetrahydro-furan-2-yl]-5-methyl-1H-pyrimidine-2,4-dione
(9b)
Yellow solid (332.4 mg, 51%); mp 121–122 °C (from MeOH/
EtOAc); Rf (EtOAc/Hex 9:1) 0.21; IR mmax (CHCl3)/cmꢂ1 3391
(O–H), 3015 (Ar C–H), 1694 (C@O), 1593 (Ar C@C); dH (400 MHz,

8252
E. M. Guantai et al. / Bioorg. Med. Chem. 18 (2010) 8243–8256
DMSO-d6) 187.4, 163.6, 162.9, 159.8, 151.5, 150.3, 148.9, 142.4,
137.8, 136.1, 131.4, 129.9, 124.5, 122.6, 119.0, 116.0, 112.4,
110.9, 109.5, 106.3, 84.4, 83.9, 61.7, 60.7, 59.3, 55.4, 37.1, 12.1;
LRMS (EI) m/z 596.4 (M+H) M+ C29H27F2N5O7 requires 595.2. Anal.
Calcd for C29H27F2N5O7ꢀ½H2O: C, 57.6; H, 4.6; N, 11.5. Found: C,
57.8; H, 4.6; N, 10.9.
H), 1656 (C@O), 1595 (Ar C@C); dH (400 MHz, CDCl3) 9.05 (1H, d,
4.6, H-8), 8.25 (1H, d, J 2.2, H-9), 8.16 (1H, s, H-6), 7.96 (1H, d, J
9.2, H-11), 7.80 (1H, d, J 15.6, H-a), 7.67 (1H, dd, J 1.8 and 8.4, H-
3), 7.65 (1H, d, J 1.8, H-1), 7.61–7.58 (3H, m, H-10, 20, 10), 7.49
(1H, d, J 4.6, H-7), 7.42 (1H, d, J 15.6, H-b), 7.21 (1H, d, H 8.4, H-
2), 6.94 (2H, d, J 8.9, H-30, 40), 5.53 (2H, s, H-5), 3.97 (3H, s, H-4);
dC (100 MHz, CDCl3) 188.6, 161.7, 151.3, 150.2, 149.8, 144.6,
144.2, 142.9, 140.9, 137.0, 132.7, 130.2, 129.6, 129.0, 127.7,
124.8, 124.5, 122.6, 119.3, 116.0, 114.5, 112.6, 111.5, 62.9, 56.1;
LRMS (EI) m/z 515.4 (M+H) M+ C28H20ClFN4O3 requires 514.2. Anal.
Calcd for C28H20ClFN4O3: C, 65.3; H, 3.9; N, 10.9. Found: C, 64.9; H,
4.1; N, 10.6.
6.5.12. 1-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-
ylmethoxy]-3-methoxy-phenyl}-3-(2,4-dimethoxy-phenyl)-
propenone (10a)
Yellow solid (228.3 mg, 41%); mp 157–158 °C (from MeOH/
EtOAc); Rf (EtOAc/Hex 7:3) 0.25; IR mmax (CHCl3)/cmꢂ1 3020 (Ar
C–H), 1649 (C@O), 1599 (Ar C@C); dH (400 MHz, CDCl3) 9.09 (1H,
br s, H-8), 8.26 (1H, s, H-9), 8.15 (1H, s, H-6), 8.04 (1H, d, J 15.7,
H-a), 7.98 (1H, d, J 9.2, H-11), 7.68–7.65 (2H, m, H-1, 3), 7.59
(1H, d, J 9.2, H-10), 7.57 (1H, d, J 8.4, H-20), 7.55 (1H, d, J 15.7, H-
b), 7.51 (1H, br s, H-7), 7.18 (1H, d, J 8.6, H-2), 6,53 (1H, dd, J 2.2
and 8.4, H-30), 6.48 (1H, d, J 2.2, H-10), 5.53 (2H, s, H-5), 3.96 (3H,
s, H-50), 3.91 (3H, s, H-40), 3.86 (3H, s, H-4); dC (75 MHz, CDCl3)
189.3, 163.0, 160.4, 151.1, 149.6, 140.1, 137.2, 133.0, 131.0,
129.7, 124.6, 122.5, 119.9, 117.2, 112.6, 111.5, 105.4, 98.5, 62.8,
56.1, 55.6, 55.5; LRMS (EI) m/z 557.5 (M+H) M+ C30H25ClN4O5 re-
quires 556.2. Anal. Calcd for C30H25ClN4O5ꢀH2O: C, 62.6; H, 4.4; N,
9.7. Found: C, 62.7; H, 4.3; N, 9.4.
6.5.16. 1-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-yl-
methoxy]-3-methoxy-phenyl}-3-(2,4-difluoro-phenyl)-prope-
none (10e)
Yellow solid (202.5 mg, 38%); mp 106–108 °C (from MeOH/
EtOAc); Rf (EtOAc/Hex 6:4) 0.3; IR mmax (CHCl3)/cmꢂ1 3000 (Ar C–
H), 1657 (C@O), 1595 (Ar C@C); dH (300 MHz, CDCl3) 9.06 (1H, d,
J 4.4, H-8), 8.27 (1H, d, J 1.9, H-9), 8.16 (1H, s, H-6), 7.96 (1H, d, J
9.3, H-11), 7.85 (1H, d, J 15.6, H-a), 7.69–7.65 (2H, m, H-1, 3),
7.59 (1H, dd, J 1.9 and 9.3, H-10), 7.55 (1H, d, J 8.3, H-20), 7.52
(1H, d, J 15.6, H-b), 7.51 (1H, d, J 4.4, H-7), 7.19 (1H, d, J 8.8, H-
2), 6.73 (1H, dd, J 2.4 and 8.3, H-30), 6.64 (1H, d, J 2.4, H-10), 5.53
(2H, s, H-5), 3.96 (3H, s, H-4); dC (75 MHz, CDCl3) 151.0, 149.8,
144.6, 137.2, 132.5, 130.9, 129.7, 128.8, 124.8, 124.6, 122.9,
122.7, 121.7, 116.0, 112.6, 111.4, 110.8, 102.2, 101.9, 98.5, 62.8,
56.1; LRMS (EI) m/z 533.4 (M+H) M+ C28H19ClF2N4O3 requires
532.1. Anal. Calcd for C28H19ClF2N4O3: C, 63.1; H, 3.6; N, 10.5.
Found: C, 63.4; H, 4.0; N, 10.2.
6.5.13. 1-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-
ylmethoxy]-3-methoxy-phenyl}-3-(2,3,4-trimethoxy-phenyl)-
propenone (10b)
Yellow solid (318.9 mg, 54%); mp 82–83 °C (from MeOH/EtOAc);
Rf (EtOAc/Hex 6:4) 0.33; IR m
max (CHCl3)/cmꢂ1 3015 (Ar C–H), 1670
(C@O), 1596 (Ar C@C); dH (400 MHz, CDCl3) 9,07 (1H, d, J 4.8, H-8),
8.27 (1H, d, J 2.0, H-9), 8.16 (1H, s, H-6), 7.98 (1H, d, J 9.2, H-11),
7.98 (1H, d, J 15.7, H-a), 7.68–7.66 (2H, m, H-1, 3), 7.60 (1H, dd, J
2.0 and 9.2, H-10), 7.57 (1H, d, J 15.7, H-b), 7.51 (1H, d, J 4.8, H-7),
7.36 (1H, d, J 8.8, H-10), 7.20 (1H, d, J 8.6, H-2), 6.72 (1H, d, J 8.8, H-
20), 5.53 (2H, s, H-5), 3.96 (3H, s, H-50), 3.95 (3H, s, H-30), 3.91 (3H,
s, H-4), 3.89 (3H, s, H-40); dC (100 MHz, CDCl3) 189.1, 155.8, 153.7,
151.1, 149.7, 144.7, 142.6, 141.1, 139.7, 137.3, 132.8, 129.7, 128.8,
124.9, 124.6, 123.9, 122.6, 122.1, 121.0, 116.0, 112.6, 111.5, 107.5,
62.9, 61.4, 60.9, 56.1; LRMS (EI) m/z 587.5 (M+H) M+ C31H27ClN4O6
requires 586.2. Anal. Calcd for C31H27ClN4O6ꢀ½H2O: C, 62.5; H, 4.5;
N, 9.4. Found: C, 62.1; H, 4.5; N, 9.2.
6.6. 1-(5-Hydroxymethyl-4-{4-[2-methoxy-4-(3-oxo-but-1-en-
yl)-phenoxymethyl]-[1,2,3]triazol-1-yl}-tetrahydro-furan-2-yl)-
5-methyl-1H-pyrimidine-2,4-dione (11)
Synthesized from 4 and enantiomerically pure (2R,4S,5S) AZT by
applying the General Method B. Fluffy white solid (3.9 g, 80%); mp
177–179 °C (from MeOH/EtOAc); Rf (MeOH/CH2Cl2 5:95) 0.42; IR
mmax (KBr)/cmꢂ1 3072 (Ar C–H), 1627 (C@O), 1595 (Ar C@C); dH
(400 MHz, DMSO-d6) 11.30 (1H, s, H-14), 8.41 (1H, s, H-6), 7.80
(1H, s, H-12), 7.56 (1H, d, J 16.3, H-a), 7.33 (1H, d, J 1.6, H-1),
7.25 (1H, dd, J 1.8 and 8.3, H-2), 7.21 (1H, d, J 8.4, H-3), 6.74 (1H,
d, J 16.3, H-b), 6.42 (1H, t, J 6.5, H-9), 5.42–5.37 (1H, m, H-7),
5.19 (2H, s, H-5), 4.25–4.22 (1H, m, H-10), 3.80 (3H, s, H-4),
3.75–3.61 (2H, m, H-11), 2.78–2.62 (2H, m, H-8), 2.30 (3H, s, H-
b0), 1.8 (3H, s, H-13); dC (100 MHz, DMSO-d6) 197.8, 163.6, 150.4,
149.6, 149.1, 143.3, 142.5, 136.1, 127.6, 125.4, 124.4, 122.7,
113.2, 110.7, 109.5, 84.4, 83.9, 61.6, 60.7, 59.2, 55.5, 37.1, 27.1,
12.1; LRMS (EI) m/z 498.5 (M+H) M+ C24H27N5O7 requires 497.2.
Anal.Calcd for C24H27N5O7ꢀ1H2O: C, 55.9; H, 5.6; N, 13.6. Found:
C, 55.6; H, 5.4; N, 14.0.
6.5.14. 1-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-
ylmethoxy]-3-methoxy-phenyl}-3-(2,4-dichloro-phenyl)-
propenone (10c)
Yellow solid (295.7 mg, 52%); mp 85–87 °C (from MeOH/
EtOAc); Rf (EtOAc/Hex 1:1) 0.2; IR mmax (CHCl3)/cmꢂ1 3018 (Ar C–
H), 1651 (C@O), 1595 (Ar C@C); dH (400 MHz, CDCl3) 9.05 (1H, d,
J 4.8, H-8), 8.27 (1H, d, J 2.2, H-9), 8.16 (1H, s, H-6), 8.01 (1H, d, J
15.6, H-a), 7.96 (1H, d, J 9.2, H-11), 7.67–7.65 (2H, m, H-1, 3),
7.59 (1H, dd, J 2.2 and 9.2, H-10), 7.56 (1H, d, J 8.4, H-20), 7.55
(1H, d, J 15.7, H-b), 7.51 (1H, d, J 4.8, H-7), 7.19 (1H, d, J 8.6, H-
2), 6.53 (1H, dd, J 2.4 and 8.4, H-30), 6.48 (1H, d, J 2.4, H-10), 5.53
(2H, s, H-5), 3.96 (3H, s, H-4); dC (100 MHz, CDCl3) 189.3, 163.0,
160.3, 151.0, 149.6, 144.5, 141.0, 140.1, 137.1, 133.0, 131.1,
129.6, 128.8, 125.0, 124.5, 122.5, 120.1, 117.2, 115.9, 112.8,
111.6, 105.5, 98.6, 62.8, 55.5; LRMS (EI) m/z 565.3 (M+H) M+
C28H19Cl3N4O3 requires 564.1). Anal. Calcd for C28H19Cl3N4O3: C,
59.4; H, 3.4; N, 9.9. Found: C, 59.7; H, 3.1; N, 9.5.
6.7. 4-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-ylmeth-
oxy]-3-methoxy-phenyl}-but-3-en-2-one (12)
Synthesized from 4 and 6 by applying the General Method B.
Off-white to pale brown solid (2.7 g, 62%); mp 82–84 °C (from
EtOAc/Hex); Rf (EtOAc/Hex 8:2) 0.20; IR mmax (KBr)/cmꢂ1 2927
(Ar C–H), 1663 (C@O), 1595 (Ar C@C); dH (300 MHz, CDCl3) 9.05
(1H, d, 4.9, H-8), 8.24 (1H, d, J 2.0, H-9), 8.14 (1H, s, H-6), 7.94
(1H, d, J 9.3, H-11), 7.58 (1H, dd, J 2.0 and 9.3, H-10), 7.48 (1H, d,
J 4.9, H-7), 7.46 (1H, d, J 15.6, H-a), 7.15–7.10 (3H, m, H-1, 2, 3),
6.62 (1H, d, J 15.6, H-b), 5.48 (2H, s, H-5), 3.91 (3H, s, H-4), 2.37
(3H, s, H-b0); dC (75 MHz, CDCl3) 198.2, 151.4, 149.9, 149.7, 144.7,
143.0, 140.8, 137.0, 129.5, 129.1, 128.6, 125.9, 124.8, 124.5,
122.7, 120.5, 116.0 (2C), 113.9, 110.4, 62.9, 55.9, 27.4; LRMS (EI)
6.5.15. 1-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-
ylmethoxy]-3-methoxy-phenyl}-3-(4-fluoro-phenyl)-
propenone (10d)
Yellow solid (266.9 mg, 52%); mp 164–166 °C (from MeOH/
EtOAc); Rf (EtOAc/Hex 6:4) 0.3; IR mmax (CHCl3)/cmꢂ1 3018 (Ar C–

E. M. Guantai et al. / Bioorg. Med. Chem. 18 (2010) 8243–8256
8253
m/z 435.2 (M+H) M+ C23H19ClN4O3 requires 434.1. Anal. Calcd for
5.43–5.37 (1H, m, H-7), 5.22 (2H, s, H-5), 4.28–4.24 (1H, m, H-
10), 3.87 (6H, s, H-30, 50), 3.84 (3H, s, H-40), 3.79 (3H, s, H-4),
3.76–3.64 (2H, m, H-11), 2.82–2.63 (2H, m, H-8), 1.82 (3H, s, H-
13); dC (75 MHz, DMSO-d6) 187.9, 163.4, 155.3, 152.7, 150.2,
149.6, 149.2, 142.5, 142.3, 141.8, 136.5, 135.9, 128.1, 124.7,
124.2, 124.1, 122.9, 122.6, 120.9, 113.6, 111.2, 109.4, 108.4, 84.3,
83.9, 61.7, 61.1, 60.6, 60.2, 59.2, 55.9, 55.5, 36.9, 11.9; LRMS (EI)
m/z 676.5 (M+H) M+ C34H37N5O10 requires 675.3. Anal. Calcd for
C
23H19ClN4O3ꢀ2H2O: C, 58.6; H, 4.9; N, 11.9. Found: C, 58.4; H,
4.6; N, 11.6.
6.8. Preparation of compounds 13a–f and 14a–f
These compounds were synthesized by condensing either 11 or
12 with appropriately substituted benzaldehydes, applying the
General Method A.
C34H37N5O10ꢀ1½H2O: C, 58.0; H, 5.7; N, 9.9. Found: C, 57.5; H,
5.7; N, 9.5.
6.8.1. 1-[5-Hydroxymethyl-4-(4-{2-methoxy-4-[5-(4-methoxy-
phenyl)-3-oxo-penta-1,4-dienyl]-phenoxymethyl}-[1,2,3]triazol-
1-yl)-tetrahydro-furan-2-yl]-5-methyl-1H-pyrimidine-2,4-
dione (13a)
6.8.4. 1-[4-(4-{4-[5-(2,4-Dichloro-phenyl)-3-oxo-penta-1,4-
dienyl]-2-methoxy-phenoxymethyl}-[1,2,3] triazol-1-yl)-5-
hydroxymethyl-tetrahydro-furan-2-yl]-5-methyl-1H-pyri-
midine-2,4-dione (13d)
Yellow solid (258 mg, 42%); mp: 192–194 °C (from MeOH/
EtOAc); Rf (MeOH/EtOAc 5:95) 0.30; IR mmax (KBr)/cmꢂ1 3340 (O–
H), 3057 (Ar C–H), 1689 (C@O), 1584 (Ar C@C); dH (400 MHz,
DMSO-d6) 11.31 (1H, s, H-14), 8.43 (1H, s, H-6), 7.81 (1H, s, H-
12), 7.75 (4H, m, H-a, a0, 10, 40), 7.41 (1H, d, J 1.7, H-1), 7.33 (1H,
dd, J 1.8 and 8.3, H-2), 7.22 (1H, d, J 15.8, H-b0), 7.19 (1H, d, J
15.9, H-b), 7.02 (2H, d, J 8.7, H-20, 30), 6.43 (1H, t, J 6.4, H-9),
5.43–5.38 (1H, m, H-7), 5.21 (2H, s, H-5), 4.26–4.23 (1H, m, H-
10), 3.83 (3H, s, H-50), 3.82 (3H, s, H-4, 3.74–3.62 (2H, m, H-11),
2.79–2.63 (2H, m, H-8), 1.81 (3H, s, H-13); dC (100 MHz, DMSO-
d6) 188.0, 163.6, 161.1, 150.8, 150.4, 149.6, 149.2, 142.5, 142.4,
142.0, 136.1, 130.2, 128.1, 127.3, 124.4, 124.1, 123.4, 122.8,
114.4, 113.9, 113.2, 110.9, 109.5, 84.4, 83.9, 61.6, 60.7, 59.3, 55.6,
55.3, 37.1, 12.1; LRMS (EI) m/z 616.2 (M+H) M+ C32H33N5O8 re-
quires 615.2. Anal. Calcd for C32H33N5O8ꢀ1½H2O: C, 59.8; H, 5.6;
N, 10.9. Found: C, 59.7; H, 5.6; N, 10.5.
Yellow solid (379 mg, 58%); mp 239–241 °C (from MeOH/
EtOAc); Rf (MeOH/EtOAc 5:95) 0.50; IR mmax (KBr)/cmꢂ1 3442 (O–
H), 3057 (Ar C–H), 1692 (C@O), 1580 (Ar C@C); dH (400 MHz,
DMSO-d6) 11.31 (1H, s, H-14), 8.43 (1H, s, H-6), 8.07 (1H, d, J 8.6,
H-30), 7.86 (1H, d, J 15.8, H-a0), 7.84 (1H, d, J 16.1, H-a), 7.81 (1H,
s, H-12), 7.74 (1H, d, J 2.1, H-1), 7.55 (1H, d, J 15.5, H-b0), 7.54
(1H, dd, J 2.1 and 8.5, H-2), 7.41 (1H, d, J 1.7, H-10), 7.33 (1H, dd,
J 1.7 and 8.5, H-20), 7.26 (1H, d, J 8.4, H-3), 7.13 (1H, d, J 16.1, H-
b), 6.43 (1H, t, J 6.6, H-9), 5.43–5.38 (1H, m, H-7), 5.22 (2H, s, H-
5), 4.26–4.23 (1H, m, H-10), 3.82 (3H, s, H-4), 3.78–3.61 (2H, m,
H-11), 2.79–2.63 (2H, m, H-8), 1.81 (3H, s, H-13); dC (100 MHz,
DMSO-d6) 187.9, 164.6, 163.6, 150.4, 149.9, 149.2, 145.4, 144.1,
142.5, 140.9, 136.1, 134.8, 131.8, 131.6, 129.5, 128.0, 126.9,
124.5, 123.1, 114.7, 110.9, 109.5, 100.8, 84.4, 83.9, 61.6, 60.7,
59.3, 55.5, 37.1, 12.1; LRMS (EI) m/z 654.6 (M+H) M+ C31H29Cl2N5O7
requires 653.1. Anal. Calcd for C31H29Cl2N5O7ꢀ½H2O: C, 56.1; H,
4.5; N, 10.6. Found: C, 56.0; H, 4.6; N, 10.7.
6.8.2. 1-[4-(4-{4-[5-(2,4-Dimethoxy-phenyl)-3-oxo-penta-1,4-
dienyl]-2-methoxy-phenoxymethyl}-[1,2,3]-triazol-1-yl)-5-hy-
droxymethyl-tetrahydro-furan-2-yl]-5-methyl-1H-pyrimidine-
2,4-dione (13b)
6.8.5. 1-[4-(4-{4-[5-(4-Fluoro-phenyl)-3-oxo-penta-1,4-dienyl]-
2-methoxy-phenoxymethyl}-[1,2,3]-triazol-1-yl)-5-hydroxy-
methyl-tetrahydro-furan-2-yl]-5-methyl-1H-pyrimidine-2,4-
dione (13e)
Yellow solid (337 mg, 52%); mp 129–131 °C (from MeOH/
EtOAc); Rf (MeOH/EtOAc 5:95) 0.30; IR mmax (KBr)/cmꢂ1 3384 (O–
H), 3057 (Ar C–H), 1692 (C@O), 1595 (Ar C@C); dH (300 MHz,
DMSO-d6) 11.20 (1H, s, H-14), 8.39 (1H, s, H-6), 7.87 (1H, d, J
16.0, H-a0), 7.78 (1H, s, H-12), 7.72 (1H, d, J 8.3, H-30), 7.66 (1H,
d, J 16.0, H-a), 7.56 (1H, dd, J 1.9 and 8.3, H-2), 7.43 (1H, d, J 1.9,
H-1), 7.39 (1H, d, J 1.9, H-10), 7.30 (1H, dd, J 1.9 and 8.4, H-20),
7.23 (1H, d, J 8.4, H-3), 7.21 (1H, d, J 16.0, H-b0), 7.11 (1H, d, J
16.0, H-b), 6.42 (1H, t, J 6.5, H-9), 5.43–5.36 (1H, m, H-7), 5.22
(2H, s, H-5), 4.28–4.24 (1H, m, H-10), 3.90 (3H, s, H-40), 3.84 (3H,
s, H-50), 3.82 (3H, s, H-4), 3.81–3.57 (2H, m, H-11), 2.82–2.62
(2H, m, H-8), 1.82 (3H, s, H-13); dC (75 MHz, DMSO-d6) 191.0,
187.9, 163.4, 162.7, 159.7, 150.2, 149.5, 142.5, 141.9, 136.8,
135.9, 129.7, 128.1, 125.3, 124.7, 124.3, 124.1, 123.1, 122.5,
113.6, 111.1, 109.4, 106.2, 98.3, 84.3, 83.9, 61.7, 60.6, 59.2, 55.6,
55.3, 36.9, 11.9; LRMS (EI) m/z 646.2 (M+H) M+ C33H35N5O9 re-
quires 645.2. Anal. Calcd for C33H35N5O9: C, 61.4; H, 5.5; N, 10.9.
Found: C, 61.7; H, 5.6; N, 10.6.
Yellow solid (193 mg, 32%); mp °C (from MeOH/EtOAc); Rf
(MeOH/EtOAc 5:95) 0.50; IR mmax (KBr)/cmꢂ1 3387 (O–H), 3010
(Ar C–H), 1688 (C@O), 1602 (Ar C@C); dH (400 MHz, DMSO-d6)
11.30 (1H, s, H-14), 8.43 (1H, s, H-6), 7.86 (1H, d, J 8.9, H-10),
7.85 (1H, d, J 8.8, H-40), 7.81 (1H, s, H-12), 7.75 (1H, d, J 16.0, H-
a0), 7.72 (1H, d, J 16.0, H-a), 7.41 (1H, d, J 1.9, H-1), 7.34 (1H, dd,
J 1.9 and 8.5, H-2), 7.32 (1H, d, J 16.1, H-b0), 7.30 (1H, d, J 8.9, H-
20), 7.29 (1H, d, J 8.9, H-30), 7.25 (1H, d, J 8.4, H-3), 7,20 (1H, d, J
16.0, H-b), 6.43 (1H, t, J 6.5, H-9), 5.42–5.38 (1H, m, H-7), 5.21
(2H, s, H-5), 4.26–4.22 (1H, m, H-10), 3.83 (3H, s, H-4), 3.77–3.61
(2H, m, H-11), 2.78–2.63 (2H, m, H-8), 1.81 (3H, s, H-13); dC
(100 MHz, DMSO-d6 188.2, 163.6, 150.4, 149.8, 149.2, 145.4,
144.1, 143.1, 142.5, 137.6, 136.1, 131.4, 130.6, 127.9, 125.4,
124.4, 124.0, 122.9, 116.0, 113.2, 110.9, 109.5, 84.4, 83.9, 67.8,
61.6, 60.7, 59.3, 55.5, 37.1, 12.1; LRMS (EI) m/z 604.4 (M+H) M+
C31H30FN5O7 requires 603.2. Anal. Calcd for C31H30FN5O7: C, 61.7;
H, 5.0; N, 11.6. Found: C, 61.4; H, 5.2; N, 11.5.
6.8.3. 1-[5-Hydroxymethyl-4-(4-{2-methoxy-4-[3-oxo-5-(2,3,4-
trimethoxy-phenyl)-penta-1,4-dienyl]-phenoxymethyl}-[1,2,3]-
triazol-1-yl)-tetrahydro-furan-2-yl]-5-methyl-1H-pyrimidine-
2,4-dione (13c)
Yellow solid (263 mg, 40%); mp 144–146 °C (from MeOH/
EtOAc); Rf (MeOH/EtOAc 5:95) 0.33; IR mmax (KBr)/cmꢂ1 3391 (O–
H), 2934 (Ar C–H), 1689 (C@O), 1584 (Ar C@C); dH (300 MHz,
DMSO-d6) 11.21 (1H, s, H-14), 8.38 (1H, s, H-6), 7.79 (1H, d, J
16.0, H-a0), 7.78 (1H, s, H-12), 7.69 (1H, d, J 16.0, H-a), 7.56 (1H,
d, J 8.8, H-20), 7.40 (1H, d, J 1.8 H-1), 7.32 (1H, dd, J 1.8 and 8.4,
H-2), 7.24 (1H, d, J 16.0, H-b0), 7.23 (1H, d, J 8.4, H-3), 7.14 (1H,
d, J 16.1, H-b), 6.91 (1H, d, J 8.9, H-10), 6.42 (1H, t, J 6.6, H-9),
6.8.6. 1-[4-(4-{4-[5-(2,4-Difluoro-phenyl)-3-oxo-penta-1,4-die-
nyl]-2-methoxy-phenoxymethyl}-[1,2,3]-triazol-1-yl)-5-hydroxy-
methyl-tetrahydro-furan-2-yl]-5-methyl-1H-pyrimidine-2,4-di-
one (13f)
Yellow solid (191 mg, 31%); mp 197–199 °C (from MeOH/
EtOAc); Rf (MeOH/EtOAc 5:95) 0.50; IR mmax (KBr)/cmꢂ1 3434 (O–
H), 3065 (Ar C–H), 1696 (C@O), 1609 (Ar C@C); dH (400 MHz,
DMSO-d6) 11.31 (1H, s, H-14), 8.43 (1H, s, H-6), 8.02 (1H, d, J 8.7,
H-30), 7.81 (1H, s, H-12), 7.77 (1H, d, J 16.0, H-a0), 7.70 (1H, d, J
16.1, H-a), 7.43 (1H, d, J 1.9, H-1), 7.42 (1H, d, J 16.1, H-b0), 7.37
(1H, d, J 2.1, H-10), 7.35 (1H, dd, J 1.9 and 8.4, H-2), 7.25 (1H, d, J

8254
E. M. Guantai et al. / Bioorg. Med. Chem. 18 (2010) 8243–8256
8.5, H-3), 7.21 (1H, dd, J 2.1 and 8.5, H-20), 7.19 (1H, d, J 16.1, H-b),
6.43 (1H, t, J 6.6, H-9), 5.42–5.38 (1H, m, H-7), 5.21 (2H, s, H-5),
4.26–4.22 (1H, m, H-10), 3.82 (3H, s, H-4), 3.77–3.61 (2H, m, H-
11), 2.78–2.63 (2H, m, H-8), 1.81 (3H, s, H-13); dC (100 MHz,
DMSO-d6) 188.1, 163.6, 153.2, 150.4, 149.9, 149.2, 143.6, 140.9,
139.7, 136.1, 132.7, 130.8, 127.9, 127.4, 124.5, 124.2, 123.1,
113.2, 112.6, 112.4, 110.9, 109.5, 104.6, 84.4, 83.9, 61.6, 60.7,
59.3, 55.5, 37.1, 12.1; LRMS (EI) m/z 622.3 (M+H) M+ C31H29F2N5O7
requires 621.2. Anal. Calcd for C31H29F2N5O7.½H2O: C, 59.0; H, 4.8;
N, 11.1. Found: C, 59.2; H, 5.0; N, 11.3.
144.8, 142.4, 140.9, 138.3, 129.5, 129.3, 129.1, 125.9, 124.9,
124.8, 124.5, 124.4, 123.5, 122.5, 121.9, 120.9, 116.1, 114.1,
111.6, 110.9, 110.5, 109.4, 107.7, 62.9, 61.5, 60.9, 56.1, 56.0; LRMS
(EI) m/z 613.3 (M+H) M+ C33H29ClN4O6 requires 612.2. Anal. Calcd
for C33H29ClN4O6ꢀ1H2O: C, 62.7; H, 4.9; N, 8.9. Found: C, 62.5; H,
4.9; N, 9.4.
6.8.10. 1-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-yl-
methoxy]-3-methoxy-phenyl}-5-(2,4-dichloro-phenyl)-penta-
1,4-dien-3-one (14d)
Yellow solid (248 mg, 42%); mp: 159–161 °C (from EtOAc); Rf
(EtOAc/Hex 8:2) 0.33; IR mmax (KBr)/cmꢂ1 3050 (Ar C–H), 1653
(C@O), 1584 (Ar C@C); dH (400 MHz, CDCl3) 9.08 (1H, d, J 4.6, H-
8), 8.26 (1H, d, J 2.1, H-9), 8.16 (1H, s, H-6), 8.04 (1H, d, J 16.0,
H-a0), 7.98 (1H, d, J 9.1, H-11), 7.71 (1H, d, J 15.9, H-a), 7.66 (1H,
d, J 8.5, H-30), 7.61 (1H, dd, J 2.1 and 9.1, H-10), 7.51 (1H, d, J 4.6,
H-7), 7.48 (1H, d, J 2.0, H-1), 7.30 (1H, dd, J 2.1 and 8.5, H-2),
7.25 (1H, dd, J 1.9 and 8.4, H-20), 7.20–7.18 (2H, m, H-10, 3), 7.04
(1H, d, J 15.9, H-b0), 6.98 (1H, d, J 15.9, H-b), 5.51 (2H, s, H-5),
3.96 (3H, s, H-4); dC (100 MHz, CDCl3) 188.3, 154.9, 153.2, 151.4,
150.3, 149.9, 144.7, 143.6, 140.9, 138.6, 137.5, 137.0, 136.4,
135.9, 131.8, 130.1, 129.5, 129.1, 128.4, 128.2 127.6, 124.8, 124.4,
123.8, 122.8, 120.6, 116.1, 110.9, 62.9, 56.1; LRMS (EI) m/z 591.1
(M+H) M+ C30H21Cl3N4O3 requires 590.1. Anal. Calcd for
6.8.7. 1-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-yl-
methoxy]-3-methoxy-phenyl}-5-(4-methoxy-phenyl)-penta-
1,4-dien-3-one (14a)
Yellow solid (199 mg, 36%); mp: 173–175 °C (from EtOAc); Rf
(EtOAc/Hex 7.3) 0.50; IR mmax (KBr)/cmꢂ1 3036 (Ar C–H), 1642
(C@O), 1580 (Ar C@C); dH (400 MHz, CDCl3) 9.08 (1H, d, J 4.6, H-
8), 8.27 (1H, d, J 2.0, H-9), 8.13 (1H, s, H-6), 7.96 (1H, d, J 9.1, H-
11), 7.71 (1H, d, J 15.6, H-a0), 7.68 (1H, d, J 15.8, H-a), 7.60 (1H,
dd, J 2.0 and 9.1, H-10), 7.58 (2H, d, J 8.8, H-10, 40), 7.51 (1H, d, J
4.6, H-7), 7.23 (1H, dd, J 1.8 and 8.3, H-2), 7.19 (1H, d, J 1.7, H-1),
7.16 (1H, d, J 8.1, H-3), 6.97 (1H, d, J 15.8 H-b0), 6.96 (1H, d, J
15.8, H-b), 6.95 (2H, dd, J 2.1 and 8.8, H-20, 30), 5.50 (2H, s, H-5),
3.96 (3H, s, H-50), 3.87 (3H, s, H-4); dC (100 MHz, CDCl3) 161.7,
151.4, 150.3, 147.3, 144.8, 142.9, 142.5, 137.0, 136.8, 130.1,
129.5, 129.1, 128.6, 124.8, 124.5 (2C), 124.2, 123.2, 122.8, 122.6,
120.6, 116.1, 114.5, 114.0, 113.6, 111.3, 110.8, 110.4, 62.9, 56.0,
55.4; LRMS (EI) m/z 553.2 (M+H) M+ C31H25ClN4O4 requires
552.1. Anal. Calcd for C31H25ClN4O4ꢀ1H2O: C, 65.1; H, 4.7; N, 9.8.
Found: C, 64.9; H, 4.7; N, 9.4.
C30H21Cl3N4O3.: C, 60.9; H, 3.6; N, 9.5. Found: C, 60.4; H, 3.7; N, 9.5.
6.8.11. 1-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-yl-
methoxy]-3-methoxy-phenyl}-5-(4-fluoro-phenyl)-penta-1,4-
dien-3-one (14e)
Yellow solid (206 mg, 38%); mp: 107–109 °C (from EtOAc); Rf
(EtOAc/Hex 7.3) 0.30; IR mmax (KBr)/cmꢂ1 3036 (Ar C–H), 1653
(C@O), 1588 (Ar C@C); dH (400 MHz, CDCl3) 9.08 (1H, d, J 4.6, H-
8), 8.26 (1H, d, J 2.1, H-9), 8.16 (1H, s, H-6), 7.97 (1H, d, J 9.1, H-
11), 7.78 (1H, d, J 16.1, H-a0), 7.70 (1H, d, J 15.9, H-a), 7.64 (1H, d,
J 8.5, H-10), 7.62 (1H, d, J 8.5, H-40), 7.60 (1H, dd, J 2.2 and 9.1, H-
10), 7.50 (1H, d, J 4.6, H-7), 7.24 (1H, dd, J 1.8 and 8.5, H-2),
7.18–7.16 (2H, m, H-1, 3), 7.14 (1H, d, J 16.1 H-b0), 6.95 (1H, d, J
15.9, H-b), 6.91 (1H, dd, J 2.1 and 8.6, H-20), 6.88 (1H, dd, J 2.5
and 8.5, H-30), 5.50 (2H, s, H-5), 3.95 (3H, s, H-4); dC (100 MHz,
CDCl3) 188.5, 151.4, 150.3, 149.9, 144.7, 143.4, 140.9, 138.5,
137.0, 135.3, 134.7, 130.7, 129.5, 129.1, 127.2, 124.8, 124.5,
124.2, 122.9, 120.6, 116.0, 113.9, 112.3, 112.1, 110.8, 104.9,
104.7, 104.5, 62.9, 56.0; LRMS (EI) m/z 541.4 (M+H) M+
C30H22ClFN4O3 requires 540.1. Anal. Calcd for C30H22ClFN4O3ꢀ½-
H2O: C, 65.5; H, 4.2; N, 10.2. Found: C, 65.9; H, 4.2; N, 10.0.
6.8.8. 1-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-yl-
methoxy]-3-methoxy-phenyl}-5-(2,4-dimethoxy-phenyl)-
penta-1,4-dien-3-one (14b)
Yellow solid (192 mg, 33%); mp: 103–105 °C (from EtOAc); Rf
(EtOAc/Hex 8:2) 0.30; IR mmax (KBr)/cmꢂ1 3079 (Ar C–H), 1656
(C@O), 1602 (Ar C@C); dH (300 MHz, CDCl3) 9.07 (1H, d, J 4.6, H-
8), 8.24 (1H, d, J 1.9, H-9), 8.14 (1H, s, H-6), 7.99 (1H, d, J 16.0,
H-a0), 7.96 (1H, d, J 8.9, H-11), 7.65 (1H, d, J 15.8, H-a), 7.60 (1H,
dd, J 2.1 and 9.1, H-10), 7.55 (1H, d, J 8.6, H-30), 7.49 (1H, d, J 4.6,
H-7), 7.21 (1H, dd, J 1.9 and 8.3, H-2), 7.16 (1H, d, J 1.9, H-1),
7.14 (1H, d, J 8.3, H-3), 7.05 (1H, d, J 16.0 H-b0), 6.98 (1H, d, J
15.8, H-b), 6.52 (1H, dd, J 2.3 and 8.6, H-20), 6.47 (1H, d, J 2.3, H-
10), 5.49 (2H, s, H-5), 3.94 (3H, s, H-40), 3.89 (3H, s, H-50), 3.85
(3H, s, H-4); dC (75 MHz, CDCl3) 183.9, 151.4, 142.0, 138.7, 137.1,
134.2, 132.6, 131.1, 130.4, 129.5, 129.1, 127.3, 124.8, 124.6,
123.9, 122.4, 120.6, 117.1, 116.5, 116.1, 114.8, 114.0, 112.8,
110.9, 109.6, 105.6, 103.6, 98.5, 63.0, 56.0, 55.6, 55.5; LRMS (EI)
m/z 583.4 (M+H) M+ C32H27ClN4O5 requires 582.2. Anal. Calcd for
C32H27ClN4O5ꢀ1½H2O: C, 63.0; H, 4.9; N, 9.2. Found: C, 62.9; H,
4.9; N, 9.8.
6.8.12. 1-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-yl-
methoxy]-3-methoxy-phenyl}-5-(2,4-difluoro-phenyl)-penta-
1,4-dien-3-one (14f)
Yellow solid (173 mg, 31%); mp: 124–126 °C (from EtOAc); Rf
(EtOAc/Hex 8:2) 0.30; IR mmax (KBr)/cmꢂ1 3043 (Ar C–H), 1653
(C@O), 1580 (Ar C@C); dH (400 MHz, CDCl3) 9.08 (1H, d, J 4.6, H-
8), 8.26 (1H, d, J 2.1, H-9), 8.16 (1H, s, H-6), 7.97 (1H, d, J 9.1, H-
11), 7.71 (1H, d, J 15.9, H-a0), 7.69 (1H, d, J 15.9, H-a), 7.62 (1H, d,
J 8.5, H-30), 7.60 (1H, dd, J 2.1 and 9.1, H-10), 7.50 (1H, d, J 4.6,
H-7), 7.24 (1H, dd, J 1.9 and 8.3, H-2), 7.18 (1H, d, J 1.9, H-1),
7.17 (1H, d, J 8.3, H-3), 7.13 (1H, d, J 1.9, H-10), 7.11 (1H, dd, J 1.8
and 8.5, H-20), 7.03 (1H, d, J 15.9, H-b0), 6.95 (1H, d, J 15.9, H-b),
5.51 (2H, s, H-5), 3.95 (3H, s, H-4); dC (100 MHz, CDCl3) 188.5,
151.4, 150.3, 149.9, 149.8, 146.5, 144.7, 143.7, 140.9, 137.0,
132.2, 131.1, 130.3, 129.5, 129.1, 125.0, 124.8, 124.5, 124.3,
122.8, 120.6, 118.6, 116.2, 116.0, 115.2, 114.0, 110.8, 105.9, 62.9,
56.0; LRMS (EI) m/z 559.3 (M+H) M+ C30H21ClF2N4O3 requires
558.1. Anal. Calcd for C30H21ClF2N4O3: C, 64.5; H, 3.5; N, 10.0.
Found: C, 64.6; H, 3.7; N, 10.2.
6.8.9. 1-{4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-yl-
methoxy]-3-methoxy-phenyl}-5-(2,3,4-trimethoxy-phenyl)-
penta-1,4-dien-3-one (14c)
Yellow solid (202 mg, 33%); mp: 96–98 °C (from EtOAc); Rf
(EtOAc/Hex 8:2) 0.30; IR mmax (KBr)/cmꢂ1 3086 (Ar C–H), 1660
(C@O), 1588 (Ar C@C); dH (400 MHz, CDCl3) 9.08 (1H, d, J 4.6, H-
8), 8.27 (1H, d, J 1.9, H-9), 8.16 (1H, s, H-6), 7.99–7.93 (2H, m, H-
11, a0), 7.66 (1H, d, J 15.8, H-a), 7.62 (1H, dd, J 2.0 and 9.1, H-10),
7.51 (1H, d, J 4.6, H-7), 7.38 (1H, d, J 8.8, H-20), 7.23 (1H, dd, J 1.7
and 8.3, H-2), 7.18–7.16 (2H, m, H-1, 3), 7.09 (1H, d, J 16.0, H-b0),
6.97 (1H, d, J 15.9 H-b), 6.72 (1H, d, J 8.8, H-10), 5.51 (2H, s, H-5),
3.97 (3H, s, H-30), 3.96 (3H, s, H-50), 3.92 (3H, s, H-40), 3.90 (3H, s,
H-4); dC (100 MHz, CDCl3) 189.1, 151.4, 150.3, 149.9, 149.5,

E. M. Guantai et al. / Bioorg. Med. Chem. 18 (2010) 8243–8256
8255
6.9. Prop-2-ynyloxy-benzene (15)
cytes (2% parasitemia and 2% hematocrit) was then added to each
of the test and control wells; 100 L of unparasitized erythrocytes
l
Phenol (10 mmol) was dissolved in 10 mL of anhydrous DMF.
Anhydrous K2CO3 (20 mmol) was then added to the solution, and
the mixture stirred at 30 °C for 30 min. Propargyl bromide (3-bro-
mopropyne, 20 mmol) was then added slowly to the reaction mix-
ture, which was subsequently stirred at 50 °C for 24 h.
(2% hematocrit) was added to the blank wells. The assay plates were
then incubated at 37 °C for 48 h in airtight gas chambers under a gas
environment of 3% O2, 4% CO2 and 93% N2. After the 48 h incubation
period, the assay plates were retrieved from the gas chambers, and
the contents of each well were re-suspended. Maintaining the same
The reaction mixture was then diluted with 100 ml ethyl ace-
tate, washed with water (2 ꢁ 50 mL), dried over anhydrous Na2SO4
and evaporated in vacuo to yield the product residue that was then
purified by column chromatography (EtOAc/hexane) to yield 15,
the structure of which was confirmed by 1H NMR, This intermedi-
ate was used for the synthesis of 16 without further purification or
characterization. dH (400 MHz, CDCl3) 7.32–7.36 (2H, m, H-1, 5),
7.02–7.06 (3H, m, H-2, 3, 4), 4.72 (2H, d, J 2.4, H-6), 2.55 (1H, t, J
2.4, H-7).
layout as the assay plate, 15
then transferred to a separate 96-well plate containing 100
l
L of the re-suspended mixtures were
lL of
Malstat reagent (1 ml/L triton, 0.33 g/L APAD and 3.3 g/L TRIS buffer)
in each well. Twenty-five microlitres of nitroblue tetrazolium
(NBT)/phenazine ethosulphate (PES) solution was then added into
each well, after which the plates were allowed to develop for
5–10 min in the dark. The absorbance of the blue formazan products
in each well was then measured at 620 nm on a 7520 Microplate
reader from Cambridge Technology Inc.
The absorbance data from the colorimetric determinations was
then transformed to represent percentage viability by adjusting for
the absorbance in the blank and control wells; this data was then
analyzed using GraphPad PrismÒ Version 4 software to yield
semi-logarithmic dose–response curves and the corresponding
IC50 values for the compounds.
For studies with the W2 strain, assays were conducted as previ-
ously reported (Shenai et al. 200348) with parasites cultured in
standard medium including 10% human serum, except that para-
site development was assessed with a FACS-based assay, as previ-
ously described (Sijwali and Rosenthal, 200449).
6.10. 7-Chloro-4-(4-phenoxymethyl-[1,2,3]triazol-1-yl)-
quinoline (16)
Synthesized from 15 and 6 by applying the General Method B.
Off-white solid (464 mg, 69%); mp: 116–117 °C (from EtOAc/hex-
ane); Rf (EtOAc/Hex 7:3) 0.42; dH (400 MHz, CDCl3) 9.08 (1H, d, J
4.6, H-9), 8.26 (1H, d, J 2.0, H-10), 8.10 (1H, s, H-7), 7.98 (1H, d, J
9.1, H-12), 7.61 (1H, dd, J 2.0 and 9.1, H-11), 7.51 (1H, d, J 4.6, H-
8), 7.32–7.37 (2H, m, H-1, 5), 7.01–7.07 (3H, m, H-2, 3, 4), 5.40
(2H, s, H-6); dC (100 MHz, CDCl3) 158.1, 151.2, 149.9, 145.3,
141.3, 137.1, 129.9 (2C), 129.6, 128.8, 124.6 (2C), 124.4, 121.6,
120.6, 116.0, 114.8, 61.9; LRMS (EI) m/z 336.0 M+ C18H13ClN4O re-
quires 336.1. Anal. Calcd for C18H13ClN4O: C, 64.2; H, 3.9; N, 16.6.
Found: C, 64.0; H, 3.5; N, 17.0.
6.13. b-Hematin inhibition assay
This assay was carried out as described by Ncokazi and Egan.41
Acknowledgments
6.11. 4-[1-(7-Chloro-quinolin-4-yl)-1H-[1,2,3]triazol-4-ylmeth-
oxy]-3-methoxy-benzaldehyde (17)
Financial support from the following sources is gratefully
acknowledged: the South African National Research Foundation
(NRF) by way of the Africa Scholarship (E.M.G.); the South African
Research Chair Initiative (SARChI) of the Department of Science
and Technology (DST) administered by the NRF, as well as from
the South African Medical Research Council (MRC) and the
University of Cape Town (K.C.); the Doris Duke Charitable
Foundation and the United States National Institutes of Health
(NIH) (P.J.R.).
Synthesized from 3 and 6 by applying the General Method B.
Off-white powder (990 mg, 84%); mp: 137–138 °C (from EtOAc/
hexane); Rf (EtOAc/Hex 4:6) 0.22; dH (400 MHz, CDCl3) 9.88 (1H,
s, H-a), 9.06 (1H, d, J 4.6, H-8), 8.26 (1H, d, J 1.9, H-9), 8.17 (1H,
s, H-6), 7.96 (1H, d, J 9.1, H-11), 7.60 (1H, dd, J 2.0 and 9.1, H-
10), 7.51 (1H, d, J 4.5, H-7), 7.45–7.48 (2H, m, H-1, 2), 7.29 (1H,
d, J 8.3, H-3), 5.54 (2H, s, H-5), 3.95 (3H, s, H-4); dC (100 MHz,
CDCl3) 190.7, 152.9, 151.3, 150.2 (2C), 144.3, 140.8, 136.9, 131.0,
129.7, 129.1, 126.7, 125.2, 124.4, 120.5, 116.0, 112.8, 109.8, 62.8,
56.2; LRMS (EI) m/z 394.0 M+ C20H15ClN4O3 requires 394.1. Anal.
Calcd for C20H15ClN4O3: C, 60.9; H, 3.8; N, 14.2. Found: C, 60.5;
H, 3.7; N, 14.5.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.bmc.2010.10.009.
6.12. Evaluation of in vitro antimalarial activity
References and notes
The in vitro antimalarial activities of compounds were evalu-
ated on CQS (D10) and CQR (Dd2 and W2) strains of P. falciparum.
The parasites were maintained in continuous in vitro culture by
standard methods.46 The cultured parasites were, whenever neces-
1. WHO Expert Committee on Malaria. WHO Technical Report Series 2000
Twentieth Report.
2. WHO. World Malaria Report 2008.
3. Rowe, A. K.; Rowe, S. Y.; Snow, R. W.; Korenromp, E. L.; Schellenberg, J. A.; Stein,
C.; Nahlen, B. L.; Bryce, J.; Black, R. E.; Steketee, R. W. Int. J. Epidemiol. 2006.
doi:10.1093/ije/dyl027.
4. WHO. Guidelines for the treatment of malaria, 2006.
5. Edwards, G.; Biagini, G. A. Br. J. Clin. Pharmacol. 2006, 61(6), 690.
6. Mutabingwa, T. K. Acta Trop. 2005, 95, 305.
7. White, N. Phil. Trans. R. Soc. Lond. 1999, B354, 739.
8. Noedl, H.; Se, Y.; Schaener, K.; Smith, B. L.; Socheat, D.; Fukuda, M. M. N. Eng. J.
Med. 2008, 359, 2619.
9. Dondorp, A. M.; Norsten, F.; Yi, P.; Das, D.; Phyo, A. P.; Tarning, J.; Lwin, K. M.;
Ariey, F.; Hanpithithakpong, W.; Lee, S. J.; Ringwald, P.; Silamut, K.; Imwong,
M.; Chotivanich, K.; Lim, P.; Herdman, T.; An, S. S.; Yeung, S.; Singhasivanon, P.;
Day, N. P. J.; Lindegardh, N.; Socheat, D.; White, N. J. N. Eng. J. Med. 2009, 361,
455.
sary, synchronized by treatment with 5%
D-sorbitol (Sigma) at the
ring stage.47
For studies with the D10 and Dd2 strains, the test compounds
were tested in duplicate on two separate occasions. The compounds
were dissolved in DMSO and serially diluted twofold with complete
culture media (RPMI 1640 culture medium (Biowhittaker) supple-
mented with glucose, HEPES buffer, hypoxanthine, 5%w/v Albumax,
sodium bicarbonate and gentamicin) to yield 100
varying concentration across a 96-well plate. The blank and nega-
tive control wells in each plate contained 100 L of complete med-
lL solutions of
l
ium instead of the test compound. Chloroquine was also tested as a
positive control. One-hundred microlitres of parasitized erythro-
10. Viegas Jnr, C.; Danuello, A.; Bolzani, V. S.; Barreiro, E. J.; Fraga, C. A. M. Curr.
Med. Chem. 2007, 14, 1829.

8256
E. M. Guantai et al. / Bioorg. Med. Chem. 18 (2010) 8243–8256
11. Walsh, J. J.; Bell, A. Curr. Pharm. Des. 2009, 15, 2970.
29. Go, M. L.; Liu, M.; Wilairat, P.; Rosenthal, P. J.; Saliba, K. J.; Kirk, K. Antimicrob.
Agents Chemother. 2004, 48, 3241.
30. Bibby, D. C.; Charman, W. N.; Charman, S. A.; Iskander, M. N.; Porter, C. J. H. Int.
J. Pharm. 1996, 144, 61.
31. WHO. Malaria and HIV interactions and their implications for Public Health
Policy, 2004.
32. Skinner-Adams, T. S.; Andrews, K. T.; Melville, L.; McCarthy, J.; Gardiner, D. L.
Antimicrob. Agents Chemother. 2007, 51, 759.
12. Mishra, S.; Narain, U.; Mishra, R.; Misra, K. Bioorg. Med. Chem. 2005, 13, 1477.
13. Griffith, D. A.; Jarvis, S. M. Biochim. Biophys. Acta 1996, 1286, 153.
14. Dechy-Cabaret, O.; Benoit-Vical, F.; Robert, A.; Meunier, B. ChemBioChem 2000,
4, 281.
15. Ferrer, R.; Lobo, G.; Gamboa, N.; Rodrigues, J.; Abramjuk, C.; Jung, K.; Lein, M.;
Charris, J. E. Sci. Pharm. 2009, 77, 725.
16. Rostovtsev, V. V.; Green, L. G.; Fokin, V. V.; Sharpless, K. B. Angew. Chem., Int. Ed.
2002, 41, 2596.
33. Egan, T. J. Mini-Rev. Med. Chem. 2001, 1, 113.
17. Tornøe, C. W.; Christensen, C.; Meldal, M. J. Org. Chem. 2002, 67, 3057.
18. Kolb, H. C.; Sharpless, K. B. Drug Discovery Today 2003, 8, 1128.
19. Wang, Q.; Chittaboina, S.; Barnhill, H. N. Lett. Org. Chem. 2005, 2, 293.
20. Feldman, A. K.; Colasson, B.; Fokin, V. V. Org. Lett. 2004, 6, 3897.
21. Tornoe, C. W.; Sanderson, S. J.; Mottram, J. C.; Coombs, G. H.; Meldal, M. J. Comb.
Chem. 2004, 6, 312.
34. Hans, R. H.; Guantai, E. M.; Lategan, C.; Smith, P. J.; Wan, B.; Franzblau, S. G.;
Gut, J.; Rosenthal, P. J.; Chibale, K. Bioorg. Med. Chem. Lett. 2010, 20, 942.
35. Ramachandra, M. S.; Subbaraju, G. V. J. Asian Nat. Prod. Res. 2006, 8, 683.
36. Narender, T.; Reddy, K. P. Tetrahedron Lett. 2007, 48, 3177.
37. de Souza, M. V. N.; Pais, K. C.; Kaiser, C. R.; Peralta, M. A.; de L Ferreira, M.;
Lourenco, M. C. S. Bioorg. Med. Chem. 2009, 17, 1474.
22. Brik, A.; Muldoon, J.; Lin, Y.-C.; Elder, J. H.; Goodsell, D. S.; Olson, A. J.; Fokin, V.
V.; Sharpless, K. B.; Wong, C.-H. ChemBioChem 2003, 4, 1246.
23. Gutteridge, C. E.; Nichols, D. A.; Curtis, S. M.; Thota, D. S.; Vo, J. V.; Gerena, L.;
Montip, G.; Asher, C. O.; Diaz, D. S.; DiTusa, C. A.; Smith, K.; Bhattacharjee, A. K.
Bioorg. Med. Chem. Lett. 2006, 16, 5682.
38. Kumar, S.; Guha, M.; Choubey, V.; Maity, P.; Bandyopadhay, U. Life Sci. 2007, 80,
813.
39. Weissbuch, I.; Leiserowitz, L. Chem. Rev. 2008, 108, 4899.
40. Tekwani, B. L.; Walker, L. A. Comb. Chem. High Throughput Screening 2005, 8, 63.
41. Ncokazi, K.; Egan, T. Anal. Biochem. 2004, 338, 306.
24. Liu, M.; Wilairat, P.; Go, M.-L. J. Med.Chem. 2001, 44, 4443.
25. Chen, M.; Theander, T. G; Christensen, S. B; Hviid, L.; Zhai, L.; Kharazmi, A.
Antimicrob. Agents Chemother. 1994, 38, 1470.
26. Chen, M.; Christensen, S. B.; Zhai, L.; Rasmussen, M. H.; Theander, T. G.;
Frøkjaer, S.; Steffansen, B.; Davidsen, J.; Kharazmi, A. J. Infect. Dis. 1997, 176,
1333.
42. Ginsburg, H.; Krugliak, M. Drug Resist. Updat. 1999, 2, 180.
43. Bray, P. G.; Mungthin, M.; Ridley, R. G.; Ward, S. Mol. Pharmacol. 1998, 54, 170.
44. Yayon, A.; Cabantchik, Z. I.; Ginsburg, H. Proc. Natl. Acad. Sci. U.S.A. 1985, 82,
2784.
45. Schlesinger, P. H.; Krogstad, D. J.; Herwaldt, B. L. Antimicrob. Agents Chemother.
1988, 32, 793.
27. Sriwilaijaroen, N.; Liu, M.; Go, M.-L.; Wilairat, P. Southeast Asian J. Trop. Med.
Public Health 2006, 37, 607.
28. Dominguez, J. N.; Charris, J. E.; Lobo, G.; de Dominguez, N. G.; Moreno, M. M.;
Riggione, F.; Sanchez, E.; Olson, J.; Rosenthal, P. J. Eur. J. Med. Chem. 2001, 36,
555.
46. Trager, W.; Jensen, J. B. Sci. New Series 1976, 193, 673.
47. Lambros, C.; Vanderberg, J. P. J. Parasitol. 1979, 65, 418.
48. Shenai, B. R.; Lee, B. J.; Alvarez-Hernandez, A.; Chong, P. Y.; Emal, C. D.; Neitz, R.
J.; Roush, W. R.; Rosenthal, P. J. Antimicrob. Agents Chemother. 2003, 47, 154.
49. Sijwali, P. S.; Rosenthal, P. J. Proc. Natl. Acad. Sci. U.S.A. 2004, 101, 4384.