Chemoselective N-benzylation of 2-thiohydantoins and 2-thiobarbituric acids catalyzed by PEG-stabilized Ni nanoparticles and their anti-microbial activities

Article abstract of DOI:10.1007/s00044-014-1008-y

An efficient one pot chemoselective N-benzylation of 2-thiohydantoins and 2-thiobarbituric acids catalyzed by PEG-stabilized Ni nanoparticles has been reported, wherein the NH group of thiohydantoins and thiobarbituric acids is selectively benzylated and

Full text of DOI:10.1007/s00044-014-1008-y

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-014-1008-y
ORIGINAL RESEARCH
Chemoselective N-benzylation of 2-thiohydantoins
and 2-thiobarbituric acids catalyzed by PEG-stabilized
Ni nanoparticles and their anti-microbial activities
Sneha
K. R. Aneja
•
Jitender M. Khurana
•
Chetan Sharma
•
Received: 29 November 2012 / Accepted: 14 April 2014
Ó Springer Science+Business Media New York 2014
Abstract An efficient one pot chemoselective N-benzy-
lation of 2-thiohydantoins and 2-thiobarbituric acids cata-
lyzed by PEG-stabilized Ni nanoparticles has been
reported, wherein the NH group of thiohydantoins and
thiobarbituric acids is selectively benzylated and no S-
benzylation is observed. Mildness and environment
friendly approach of the protocol gives it an edge over
other conventional methods. These compounds were tested
in vitro for their antibacterial activity against Gram-posi-
tive bacteria namely, Staphylococcus aureus and Bacillus
subtilis and their inhibitory action against two strains of
fungus.
Furthermore, many thiohydantoins are responsible for inhi-
bition of fatty acid hydrolases (Muccioli et al., 2006), gly-
cogen phosphorylases (Agasimundin et al., 1998), amylases
(Kandra et al., 2005), and serine proteases (He et al., 2000).
5-Arylidene-2-thiohydantoins are reported to possess anti-
mycobacterial and anti-microbial activities (Szyma n´ ska
et al., 2002). Recent studies have shown that some arylid-
ene(thio)hydantoin derivatives possess P-gp modulating
properties in cancer cells in the range of verapamil or higher
(Spengler et al., 2010). Handzlik and co-workers have syn-
thesized a series of new 5-arylidene(thio)hydantoin deriva-
tives as modulators of cancer efflux pump (Handzlik et al.,
2012). Thiohydantoin derivatives have been designed and
Keywords Ni nanoparticles ꢀ N-Benzylation ꢀ
synthesized for detecting tau pathology in the brains of
patients with Alzheimer’s disease (Aly et al., 2004). 5-Ben-
zylidene-2-thiohydantoins have been reported to undergo
Mannich reaction with formaldehyde and morpholine to give
the corresponding Mannich products (Ono et al., 2011).
Barbituric acid derivatives namely, arylidene barbituric
acids as well as their 2-thio analogs are useful as inter-
mediates in synthesis of heterocyclic compounds (Bojarski
et al., 1985), benzyl barbituric derivatives (Frangin et al.,
1986), oxadiazaflavines (Figueroa-Villar et al., 1992), and
unsymmetrical disulfides (Tanaka et al., 1988). 5-Benzyl-
idene thiobarbiturate derivatives have been evaluated as
tyrosinase inhibitors and antibacterial agents (Yan et al.,
2009).
2
-Thiohydantoin ꢀ 2-Thiobarbituric acid ꢀ
Anti-microbial activity
Introduction
Thiohydantoins and their derivatives represent an important
class of biologically active molecules having broad medicinal
applications viz. anticancer (Shih et al., 2004; Takahashi
et al., 2005), anticonvulsant (Chui et al., 2004), anti-microbial
(
Gulati et al., 1994), hypolipidemic (Tompkin, 1986), hypo-
tensive (Gadwood et al., 1993), and agrochemical (herbicidal
and fungicidal) (Mizuno et al., 2000) applications.
In recent times, there has been budding interest in using
nickel nanoparticles in organic synthesis because of their
potent catalytic activity, easy preparation and high stabil-
ity. Ni nanoparticles overcome the shortcoming of recy-
clability of homogeneous nickel catalysts thereby behaving
as an efficient heterogeneous catalyst. In continuation to
our ongoing interest (Khurana and Vij, 2010, 2011,
Khurana et al., 2012) in identifying newer applications of
Sneha ꢀ J. M. Khurana (&)
Department of Chemistry, University of Delhi,
Delhi 110007, India
e-mail: jmkhurana1@yahoo.co.in
C. Sharma ꢀ K. R. Aneja
Department of Microbiology, Kurukshetra University,
Kurukshetra 136119, Haryana, India
123

Med Chem Res
Fig. 1 a TEM image of PEG-
stabilized Ni nanoparticles. The
scale bar corresponds to 20 nm
in the image; b X-ray diffraction
pattern of PEG-Ni nanoparticles
nickel nanoparticles, we have investigated a new procedure
for N-benzylation of 2-thiohydantoin and 2-thiobarbituric
acid derivatives in presence of Ni nanoparticles as active
catalysts.
higher temperatures gave a mixture of products instead of
the desired product. We speculated this to be because of the
unprotected C-5 position. We thought that second approach
of Knoevenagel condensation of thiohydantoin with aryl
aldehyde followed by benzylation could be productive.
Alternatively, we thought a one pot reaction of the three
components could be attempted. Therefore, we attempted a
one pot Knoevenagel condensation and benzylation. The
reaction between 4-nitrobenzaldehyde (1.0 equiv.), 2-thi-
ohydantoin (1.0 equiv.), and benzyl bromide (2.0 equiv.) in
Ni nanoparticles dispersion in ethylene glycol (2 mL/0.1 g
aldehyde) at room temperature showed the formation of a
new product which was believed to be 5-(4-nitrobenzyli-
dene)-2-thioxo-imidazolidin-4-one, the Knoevenagel con-
densation product rather than the desired product, as
identified by co-TLC with authentic sample. It is likely that
the reaction came to a halt after first step. The above
reaction was then repeated at 50 °C under otherwise
identical conditions. A new spot was observed as moni-
tored by TLC using petroleum ether: ethyl acetate (60:40,
v/v) as eluent which did not correspond to the Knoevenagel
condensation product. However, the reaction was incom-
plete even after long time of stirring (6 h). Encouraged by
the result, the above reaction was repeated at still higher
temperature of 70 °C. The reaction was complete after
30 min, and after work-up, 3-benzyl-5-(4-nitrobenzyli-
dene)-2-thioxoimidazolidin-4-one (IIIa) was isolated in
90 % yield. The benzylation took place exclusively at N-3
and the N-1 position remained intact. Also, no S-alkylated
product was obtained.
Results and discussion
We report in this paper, a novel protocol for the synthesis
of new N-benzylated arylidene thiohydantoins viz. 3-ben-
zyl-5-arylidene-2-thioxoimidazolidin-4-ones (IIIa-h) and
N-benzylated arylidene thiobarbiturates viz. 1,3-dibenzyl-
5
-arylidene-2-thioxodihydropyrimidine-4,6(1H,5H)-diones
(
IVa-i) in ethylene glycol using PEG-stabilized Ni nano-
particles as semi-heterogeneous catalysts. Monodispersed
Ni nanoparticles were synthesized from NiCl .6H O as
2
2
metal salt precursor and NaBH as reducing agent using
4
polyethylene glycol (PEG-4000) as stabilizing agent. The
average size of metal nanoparticles was found to be 7 nm
through TEM (Fig. 1a) and XRD analysis (Fig. 1b). XRD
pattern confirmed the metallic nature of Ni nanoparticles.
o
o
The X-ray diffraction shows peaks at 2h = 44.5 , 51.8 ,
and 76.4 , corresponding to the (111), (200), and (222)
o
lattice planes which clearly indicate the presence of pure
elemental Ni with FCC structure. The size from the XRD
data was calculated to be 6.9 nm and is consistent with
TEM results.
The formation of N-benzylated arylidene thiohydantoins
can be achieved in two steps either by benzylation of thi-
ohydantoins followed by Knoevenagel condensation with
aldehydes or by Knoevenagel condensation of thiohydan-
toin with aldehydes followed by benzylation. We followed
the former approach. Therefore, N-benzylation of 2-thi-
ohydantoin was attempted in PEG-Ni nanoparticles dis-
persion in ethylene glycol. The reaction of 2-thiohydantoin
Attempts to obtain 1,3-dibenzyl derivative of thiohyd-
antoin by varying the reaction conditions (elevated tem-
peratures and higher catalyst loading) were unsuccessful.
The reaction of the pre-formed Knoevenagel product, 5-(4-
nitrobenzylidene)-2-thioxoimidazolidin-4-one, with double
molar ratio of benzyl bromide also resulted in the forma-
tion of IIIa only instead of the dibenzyl product. Since the
dibenzylated product could not be obtained, a reaction was
attempted with equivalent amounts of 4-nitrobenzaldehyde,
(
1.0 equiv.) and benzyl bromide (2.0 equiv.) was carried
out in Ni nanoparticles dispersion in ethylene glycol
2.0 mL/0.1 g of substrate) at different temperatures. There
was no reaction at room temperature while reaction at
(
1
23

Med Chem Res
2
-thiohydantoin, and benzyl bromide at 70 °C in presence
of PEG-Ni nanoparticles dispersion in ethylene glycol
2 mL/0.1 g of Ia). It was observed that the reaction was
In order to authenticate the effective involvement of Ni
nanoparticles in the reaction, a blank reaction was carried
out with Ia, IIa, and benzyl bromide in ethylene glycol in
the absence of Ni nanoparticles at 70 °C. The reaction was
incomplete even after 7 h, and the product isolated was
identified to be Knoevenagel product 5-(4-nitrobenzyli-
dene)-2-thioxoimidazolidin-4-one and not the desired
product IIIa. In another experiment, Ni nanoparticles were
isolated from the sample, followed by washing several
times with absolute ethanol and subsequently redispersing
(
complete in 30 min with 91 % yield of IIIa. These results
are listed in Table 1.
The scope of the reaction was extended to different
aldehydes with equivalent amounts of 2-thiohydantoin and
benzyl bromide under otherwise similar conditions (Eq. 1).
The corresponding novel products (IIIb-h) were obtained in
high yields. The results are summarized in Table 2.
Br
S
H
S
N
N
PEG-Ni nps, EG
ArCHO
I
+
+
NH
HN
o
1
7
0 C
O
O
Ar
IIa
IIIa-h
Encouraged by the results obtained with 2-thiohydantoin,
we decided to extend the protocol with 2-thiobarbituric acid.
A reaction of 4-nitrobenzaldehyde (1.0 equiv.), 2-thiobarbi-
turic acid (1.0 equiv.), and benzyl bromide (2.0 equiv.) was
attempted in Ni nanoparticles dispersion in ethylene glycol
them in ethylene glycol. The dispersion so obtained was
then used for the reaction of Ia, IIa, and benzyl bromide.
The reaction was complete within 35 min and 90 % of IIIa
was isolated.
Plausible mechanism for the formation of 3-benzyl-5-
benzylidene-2-thiohydantoin is outlined in Scheme 1.
The intermediate formation of 5-arylidene-2-thiohydantoin
has been confirmed by an independent reaction. We carried out
the synthesis of IIIa in two steps. First, the Knoevenagel
product 5-(4-nitrobenzylidene)-2-thioxoimidazolidin-4-one
was prepared by the condensation of 4-nitrobenzaldehyde (Ia)
and 2-thiohydantoin in presence of PEG-stabilized Ni nano-
particles at room temperature. It was then treated with benzyl
bromide in presence of PEG-stabilized Ni nanoparticles dis-
persion in ethylene glycol at 70 °C to give the product IIIa
(88 %) in 35 min. This supports the proposed pathway for the
intermediate 5-arylidene-2-thiohydantoins.
(
2.0 mL/0.1 g Ia) at room temperature. No reaction occurred
since thiobarbituric acid has low solubility in ethylene glycol
at room temperature. Considering this, the reaction was car-
ried out at 70 °C. The reaction was found to be complete in
4
5 min as monitored by TLC using petroleum ether: ethyl
acetate (60:40, v/v) as eluent. The product obtained after
work-up was identified to be 1,3-dibenzyl-5-(4-nitrobenzyli-
dene)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione (92 %).
The benzylation at N-1 and N-3 positions is equally probable
in 2-thiobarbituric acid unlike in 2-thiohydantoin where N-3
position is more reactive due to its favorable location between
two activating groups. A variety of aryl aldehydes were
screened to establish the generality of the reaction. All the
reactions proceeded smoothly, and the desired products were
obtained in high yields (IVa-i) (Eq. 2, Table 3).
The recyclability of Ni nanoparticles in these reactions
was also investigated. The catalyst could be recycled. The
product was separated from the reaction mixture by
Br
S
N
O
H
N
S
O
2
PEG-Ni nps, EG
N
Ar
ArCHO
I
+
+
HN
o
7
0 C
O
O
IVa-i
IIb
123

Med Chem Res
Table 1 Reaction of 4-nitrobenzaldehyde (Ia, 1.0 equiv.), 2-thi-
ohydantoin (IIa, 1.0 equiv.), and benzyl bromide (2.0 equiv.) in
presence of PEG-Ni nanoparticles
Table 3 Ni nanoparticles catalyzed synthesis of 1,3-dibenzyl-5-ary-
lidene-2-thioxodihydro pyrimidine-4,6(1H,5H)diones (IV)
Entry Ar (ArCHO)
Product Time (min) (%) Yield
Entry
Volume of
Ni nps dispersion
wt%
(Ni: 0.1 g
of Ia)
Temp.
(°C)
Time
(h)
(%)
Yield
1.
4-O
4-FC
3-O NC
2,5-(OMe)
2
NC
6
H
4
(Ia)
(Id)
(Ie)
IVa
IVb
45
75
40
60
50
60
45
60
35
92
88
90
89
89
91
90
87
92
(mL)/0.1 g of Ia
2
.
H
6 4
a
3.
4.
5.
6.
7.
8.
9.
2
6
H
4
IVc
1.
2.
3.
4.
5.
6.
7.
8.
2.0
2.0
2.0
2.0
2.0
4.0
8.0
2.0
0.0235
0.0235
0.0235
0.0235
0.0235
0.0470
0.0940
0.0235
r.t.
50
3
85
b
2
C
H
6 3
(Ii) IVd
(Ij) IVe
IVf
4
60
c
4-(Me)
2-MeC
2
6
CHC H
4
70
0.5
0.5
0.5
0.5
0.5
0.5
90
c
6
H
4
(Ik)
(Il)
100
140
70
91
c
2-O
2
NC
6
H
4
IVg
90
c
2-Naphthyl (Im)
3-ClC (In)
IVh
86
c
H
6 4
IVi
70
82
c,d
70
91
Reaction carried out with aldehyde (1.0 equiv.), 2-thiobarbituric acid
(1.0 equiv.) and benzyl bromide (2.0 equiv.) at 70 °C in presence of
PEG-Ni nps in ethylene glycol (2.0 mL/0.1 g of I)
r.t. room temperature
a
Knoevenagel product, 5-(4-nitro-benzylidene)-2-thioxo-imidazoli-
din-4-one, was isolated
b
Incomplete reaction
(Staphylococcus aureus, Bacillus subtilis) bacteria and
antifungal activity against Aspergillus niger and Aspergillus
flavus. However, these compounds did not exhibit any
activity against Gram-negative (Escherichia coli and Pseu-
domonas aeruginosa) bacteria. Positive controls produced
significantly sized inhibition zones against the tested bacte-
ria and fungi, however, negative control produced no
observable inhibitory effect against any of the test organism
as shown in Table 4 and Table 6.
c
3
was isolated
-Benzyl-5-(4-nitrobenzylidene)-2-thioxoimidazolidin-4-one (IIIa)
d
Reaction carried out with 4-nitrobenzaldehyde (1.0 equiv.), 2-thi-
ohydantoin (1.0 equiv.) and benzyl bromide (1.0 equiv.)
Table 2 Ni nanoparticles catalyzed synthesis of 3-benzyl-5-aryli-
dene-2-thioxoimidazolidin-4-ones (III)
Entry Ar (ArCHO)
Product Time (min) (%) Yield
The tested compounds showed zone of inhibition rang-
ing between 13.6 mm and 21.3 mm against the Gram-
positive bacteria. On the basis of zone of inhibition pro-
duced against the test bacterium, compound IVe was found
to be most effective against B.subtilis and S. aureus, with
zone of inhibition of 19.6 mm and 21.3 mm, respectively
(Table 4; Fig. 2). In the whole series, the MIC of chemical
compounds ranged between 32 and 512 lg/mL against
Gram-positive bacteria. Compound IVe was found to be
best as it exhibited the lowest MIC of 32 lg/mL against
B.subtilis and two compounds namely, IVe and IVg
showed lowest MIC of 64 lg/mL against S. aureus
1
2
3
4
5
6
7
.
.
.
.
.
.
.
2,4-Cl
3,4-(MeO)
4-FC
3-O NC
2
C
6
H
3
(Ib)
IIIb
(Ic) IIIc
IIId
50
30
45
40
30
30
60
91
93
90
89
94
93
92
2
C
6
H
3
6
H
4
(Id)
2
6
H
4
(Ie)
(If)
(Ig)
IIIe
4-(NC)C
3-(NC)C
6
H
4
IIIf
6
H
4
IIIg
4-(CH
3
)
2
NC
6
H
4
(Ih)
IIIh
Reaction carried out with aldehyde (1.0 equiv.), 2-thiohydantoin (1.0
equiv.), and benzyl bromide (1.0 equiv.) at 70 °C in presence of PEG-
Ni nps in ethylene glycol (2.0 mL/0.1 g of I)
(
Table 5; Fig. 3).
extraction with ethyl acetate several times as it was com-
pletely immiscible with ethylene glycol at room tempera-
ture. The recovered ethylene glycol layer containing the Ni
nanoparticles could be reused for the subsequent cycles
after sonication. It was found that the catalyst retained
optimum activity till four cycles (IIIa, 90–84 %) after
which a drop in yield (76 %) was observed.
All the compounds were screened for their antifungal
activity also. Two compounds, IIIe and IVe, showed more
than 50 % inhibition of mycelial growth against A. flavus
whereas only one compound IVe showed more than 50 %
inhibition of mycelial growth against A. niger (Table 6;
Fig. 4).
Among all the compounds, compound IVe showed good
activity against the Gram-positive bacteria and tested
fungal pathogens. Therefore, this compound can be further
explored in the pharmaceutical industry, after testing its
toxicity to human beings.
Biological screening
A total of 16 chemical compounds were screened for their
antibacterial and antifungal activity. The compounds pos-
sessed variable antibacterial activity against Gram-positive
In conclusion, we have reported a mild and highly
chemoselective N-benzylation of 2-thiohydantoins and
1
23

Med Chem Res
Scheme 1 Proposed pathway
for the synthesis of 3-benzyl-5-
arylidene-2-thiohydantoin
PEG
Ni
PEG
+
O
Ni
H
H
H
O
S
N
N
Ar C
H
Ar
HN
N
S
H
O
Br
PEG-Ni nps
PEG
Ni
O
O
H
N
N
Ar C
H
Ar C
N
H
H
S
N
H
S
Table 4 Antibacterial activity
of compounds III and IV
through agar well diffusion
method
a
Compounds
Diameter of growth of inhibition zone (mm)
Staphylococcus aureus
Bacillus
subtilis
Escherichia coli
Pseudomonas aeruginosa
IIIa
13.6
13.3
15.6
14.3
14.6
16.3
14.3
15.3
14.6
13.3
13.6
19.6
16.3
17.6
15.6
17.3
26.6
15.3
15.6
17.3
15.6
14.3
18.0
15.6
16.3
16.3
15.3
14.6
21.3
18.6
19.6
17.3
18.6
24.0
–
–
–
–
–
–
–
–
–
–
IIIb
IIId
IIIe
IIIf
IIIg
IIIh
IVa
–
–
–
–
IVb
–
–
IVc
–
–
IVd
–
–
–
No activity
IVe
–
–
a
Values, including diameter of
the well (8 mm), are means of
three replicates
IVf
–
–
IVg
–
–
IVh
–
–
The significance of the bold
values indicate the highest
antimicrobial activity of that
particular compound
IVi
–
–
Ciprofloxacin
25.0
22.0
2
-thiobarbituric acids to give novel 3-benzyl-5-arylidene-2-
Experimental
thioxoimidazolidin-4-ones and 1,3-dibenzyl-5-arylidene-2-
thioxodihydropyrimidine-4,6(1H,5H)-diones, respectively.
High yields, mild reaction conditions, and environment
friendliness of the protocol make it highly desirable. These
derivatives were evaluated for their anti-microbial activi-
ties, of which, some have shown good antibacterial and
antifungal activities.
All the chemicals used were of research grade and were
used without further purification. Transmission electron
microscopy for size and morphology characterization was
2
obtained on TECNAI G U-TWIN (300 kV). X-ray dif-
1
fraction pattern was obtained on BRUKER D8. H NMR
1
and C NMR spectra were recorded on JEOL JNM ECX-
3
123

Med Chem Res
Fig. 2 Comparison of diameter
of growth of inhibition of
compounds III and IV with
standard drug
Table 5 Minimum inhibitory concentration (MIC) (in lg/mL) of
compounds using modified agar well diffusion method
400P (400 MHz) with DMSO-d as solvent and TMS as
6
internal standard. IR spectra were recorded on Perkin-
Elmer FT-IR SPECTRUM-2000. Mass spectra were
recorded on JEOL-AccuTOF JMS–T100 mass spectrome-
ter having a DART source. Melting points were recorded
on a Tropical Labequip apparatus and are uncorrected.
Compound
Staphylococcus aureus
Bacillus subtilis
IIIa
256
512
128
256
256
128
128
128
128
512
256
64
128
128
128
128
256
64
IIIb
IIId
IIIe
Preparation of Ni nanoparticles
IIIf
IIIg
Ni nanoparticles were prepared as reported ( Khurana and
IIIh
IVa
128
128
128
128
256
32
-
4
Vij, 2011). To a 2 9 10 M solution of NiCl .6H O
2
2
IVb
(0.0048 g) in ethylene glycol (100 mL) placed in a 250 mL
R.B. flask fitted with a reflux condenser, polyethylene
glycol i.e., PEG-4000 (0.024 g) was added. The mixture
was stirred until complete dissolution of PEG. The solution
IVc
IVd
IVe
IVf
128
64
64
˚
was heated in an oil-bath maintained at 120C. At this
IVg
64
temperature, 0.36 g of NaBH was added to the solution.
4
IVh
128
128
6.25
128
64
The system was maintained under magnetic stirring at
˚
IVi
1
20C for 2 h. Formation of black-colored particles indi-
Ciprofloxacin
6.25
cated the successful synthesis of Ni nanoparticles. The
sample for TEM analysis was obtained by the addition of
acetone to the Ni nanoparticles dispersion in ethylene
The significance of the bold values indicate the highest antimicrobial activity
of that particular compound
Fig. 3 Comparison of MIC of
compounds III and IV with
standard drug
1
23

Med Chem Res
Table 6 Antifungal activity of chemical compounds through poi-
soned food method
General procedure for the synthesis of 3-benzyl-5-
arylidene-2-thioxoimidazolidin-4-ones (IIIa–h)
Compound
Mycelial growth inhibition (%)
In a typical reaction, a mixture of aromatic aldehyde (1.0
equiv.), 2-thiohydantoin (1.0 equiv.), and benzyl bromide
(1.0 equiv.) in Ni nanoparticles dispersion in ethylene
glycol [2.0 mL of dispersion (0.0235 wt% of Ni)/0.1 g
aldehyde] was stirred thoroughly in a 50 mL R. B. flask
maintained at 70 °C. The reaction progress was moni-
tored by TLC, using petroleum ether/ethyl acetate
Aspergillus niger
Aspergillus flavus
IIIa
IIIb
IIId
IIIe
35.5
42.2
44.4
48.8
33.3
35.5
34.4
41.1
43.3
48.8
37.7
51.1
45.5
44.4
41.1
38.8
81.1
37.7
44.4
45.5
51.1
38.8
38.8
38.8
45.5
47.7
45.5
43.3
55.5
47.7
48.8
43.3
42.2
77.7
IIIf
(60:40) as eluent. Upon completion, 15 mL of water was
IIIg
IIIh
IVa
added to the reaction mixture, and the solid product was
filtered at pump, washed with water, dried, and recrys-
tallized from hot ethanol. The products were identified
by spectral data.
IVb
IVc
IVd
IVe
3-Benzyl-5-(4-nitrobenzylidene)-2-thioxoimidazolidin-4-
IVf
one (IIIa)
IVg
IVh
IVi
Yellow solid; Yield = 90 %; m.p. 233–235 °C; IR (KBr,
-
1
cm ) tmax = 3423, 3133, 2823, 1715, 1630, 1500, 1337,
Fluconazole
1
1
183, 1071; H NMR (400 MHz, DMSO-d ) d: 11.99 (s,
6
The significance of the bold values indicate the highest antimicrobial
activity of that particular compound
1H, NH), 8.40–8.36 (m, 2H, Ar–H), 8.23–8.20 (m, 2H,
Ar–H), 7.49 (d, J = 7.4 Hz, 2H, Ar–H), 7.33-7.21 (m,
1
3
3H, Ar–H), 6.78 (s, 1H, CH), 4.57 (s, 2H, CH2);
C
NMR (100 MHz, DMSO-d ) d: 170.23(C=S), 167.31
6
glycol, followed by centrifugation (6,000 rpm). The parti-
cles, so obtained, were washed free of any residual com-
ponents using ethanol. Subsequently, a drop of methanol
dispersion of Ni nanoparticles was placed on carbon-coated
Cu grid (mesh size 300). Sample for the X-ray diffraction
study was obtained by depositing a thin coating of the
isolated Ni nanoparticles (dispersed in absolute ethanol)
onto a glass plate followed by vacuum drying.
(C=O), 146.82(CH, C
CNH), 132.05(C, C Ph), 129.09(CH, C
128.58(CH, C Ph, CPh & C Ph), 127.56(CH, C
Ph), 123.66(CH, C Ar & C Ar), 117.52(CH, C-CAr),
33.62(CH , NCPh); MS (ESI) m/z calcd. = 339.07,
found: 340.08 [M ?H]. Anal. Calcd for C17H N O S :
13 3 3
4
Ar), 140.93(C, C
1
Ar), 136.69(C
Ar, & C Ar),
Ph &
5
-
1
2
6
3
5
2
C
6
3
5
2
?
C, 60.17; H, 3.86; N, 12.38; S, 9.45 %. Found: C, 60.11;
H, 3.83; N, 12.31; S, 9.40 %.
Fig. 4 Comparison of
antifungal activity of
compounds III and IV with
standard drug
123

Med Chem Res
3
-Benzyl-5-(2,4-dichlorobenzylidene)-2-
C Ar), 115.63(CH, C Ar), 33.43(CH , NCPh); MS (ESI)
5
3
2
?
m/z calcd. = 312.07, found: 313.08 [M ?H]; Anal. Calcd
thioxoimidazolidin-4-one (IIIb)
for C H FN OS : C, 65.37; H, 4.19; F, 6.08; N, 8.97; S,
2
1
7
13
Yellow solid; Yield = 91 %; m.p. 218–220 °C; IR (KBr,
10.27 %. Found: C, 65.29; H, 4.13; F, 6.02; N, 8.92; S,
10.24 %.
-1
cm ) t
= 3392, 3087, 2809, 1712, 1630, 1504, 1412,
max
1
1
8
7
7
1
184; H NMR (400 MHz, DMSO-d ) d: 12.04 (s, 1H, NH),
6
.86 (d, J = 8.8 Hz, 1H, Ar–H), 7.72–7.71 (m, 1H, Ar–H),
.57–7.54 (m, 1H, Ar–H), 7.47 (d, J = 7.6 Hz, 2H, Ar–H),
.36–7.32 (m, 2H, Ar–H), 7.28–7.24 (m, 1H, Ar–H), 6.90 (s,
3-Benzyl-5-(3-nitrobenzylidene)-2-thioxoimidazolidin-4-
one (IIIe)
1
3
H, CH), 4.55 (s, 2H, CH2); C NMR (100 MHz, DMSO-
Yellow solid; Yield = 89 %; m.p. 228–230 °C; IR (KBr,
-
1
1
= 3435, 3080, 2926, 1717, 1525, 1357, 1182; H
d ) d: 170.19 (C=S), 166.87(C=O), 140.88 (C -CNH),
cm ) t
6
5
max
1
36.89 (CH, C Ph), 135.03(CCl-C Ar), 134.36(CCl-C Ar),
1
NMR (400 MHz, DMSO-d ) d: 11.99 (s, 1H, NH), 9.30–9.28
2
4
6
1
33.26(C, C Ar), 130.64(CH, C Ar), 129.22(CH, C Ar),
1
(m, 1H, Ar–H), 8.45–8.43 (m, 1H, Ar–H), 8.19–8.17 (m, 1H,
6
3
1
29.05(CH, C Ar), 128.56(CH, C Ph & C Ph), 127.75(C Ph
5 3 5 2
Ar–H), 7.72-7.68 (m, 1H, Ar–H), 7.55–7.53 (m, 2H, Ar–H),
&
C Ph), 127.52(C- Ph), 112.94(CH, C-CAr), 33.56(CH ,
6
7.33–7.25 (m, 3H, Ar–H), 6.87 (s, 1H, CH), 4.59 (s, 2H, CH );
2
4
2
1
3
NCPh); MS (ESI) m/z calcd. = 362.00, found: 363.02
C NMR (100 MHz, DMSO-d ) d: 170.19(C, C=S),
6
?
M ?H], 365.02 [(M ?H) ? 2]; Anal. Calcd for C H
?
[
166.32(C, C=O), 148.10(C-NO , C Ar), 140.87(C, C CNH),
2 3 5
1
7
12
Cl N OS : C, 56.21; H, 3.33; Cl, 19.52; N, 7.71; S, 8.83 %.
2
137.47(C, C Ph), 137.06(C, C Ar), 135.98(CH, C Ar),
1 1 6
2
Found: C, 56.17; H, 3.30; Cl, 19.50; N, 7.67; S, 8.78 %.
130.12(CH, C Ar), 129.08(CH, C Ar), 128.58(CH, C Ph &
4 2 3
C Ph), 127.56(CH, C Ph & C Ph), 125.04(CH, C Ph),
4
5
2
6
3
-Benzyl-5-(3,4-dimethoxybenzylidene)-2-
123.55(CH, C Ar), 117.90(CH, C–Ar), 33.41(CH , NCPh);
5 2
?
MS (ESI) m/z calcd. = 339.07, found: 340.08 [M ?H];
thioxoimidazolidin-4-one (IIIc)
Anal. Calcd for C H N O S : C, 60.17; H, 3.86; N, 12.38; S,
17 13 3 3
Yellow solid; Yield = 93 %; m.p. 195–197 °C; IR (KBr,
9.45 %. Found: C, 60.13; H, 3.82; N, 12.33; S, 9.42 %.
-1
1
= 3367, 3043, 2816, 1714, 1576, 1174; H NMR
cm ) t
max
(
400 MHz, DMSO-d ) d: 11.74 (s, 1H, NH), 8.17 (s, 1H,
4-((1-Benzyl-5-oxo-2-thioxoimidazolidin-4-
6
Ar–H), 7.60–7.57 (m, 1H, Ar–H), 7.49 (d, J = 7.3 Hz, 2H,
ylidene)methyl)benzonitrile (IIIf)
Ar–H), 7.34–7.25 (m, 3H, Ar–H), 7.01 (d, J = 8.8 Hz, 1H,
Ar–H), 6.73 (s, 1H, CH), 4.57 (s, 2H, CH ), 3.79 (s, 3H,
2
Yellow solid; Yield = 94 %; m.p. 230–232 °C; IR (KBr,
1
OCH ), 3.69 (s, 3H, OCH ); C NMR (100 MHz, DMSO-d )
3
-1
3
3
6
cm ) t
max
= 3447, 3128, 2222, 1717, 1632, 1501, 1406,
1
d: 170.56(C, C=S), 162.25(C, C=O), 150.45(COMe, C Ar),
1182; H NMR (400 MHz, DMSO-d ) d: 11.99 (s, 1H, NH),
3
6
1
48.55(COMe, C Ar), 137.36(C, C CNH), 137.18(C, C Ph),
4
8.33 (d, J = 8.0 Hz, 2H, Ar–H), 7.86 (d, J = 8.0 Hz, 2H, Ar–
5
1
1
28.87(C, C Ar), 128.62(CH, C Ph & C Ph), 127.54(CH,
1
H), 7.50 (d, J = 7.2 Hz, 2H, Ar–H), 7.36–7.32 (m, 2H, Ar–H),
3
5
C Ph), 127.18(CH, C Ph), 126.13(CH, C Ph), 121.79 (CH,
2
7.27–7.26 (m, 1H, Ar–H), 6.77 (s, 1H, CH), 4.56 (s, 2H, CH );
2
6
4
13
C Ar), 113.60(CH, C Ar & C Ar), 111.49(CH, C-CAr),
6
C NMR (100 MHz, DMSO-d ) d: 170.24(C, C=S),
2
5
6
5
5.51(C, OMe), 55.09(C, OMe), 33.13(CH , NCPh); MS
2
166.64(C, C=O), 141.31(C, C Ar), 138.87(C, C Ar), 136.93(C,
1 1
?
(ESI) m/z calcd. = 354.10, found: 355.14 [M ?H]; Anal.
Calcd for C H N O S : C, 64.39; H, 5.12; N, 7.90; S,
C1Ph), 132.44, 132.33, 131.66, 129.83, 129.08, 128.60, 127.55,
1
9
18
2
3
118.89, 118.23, 110.93, 105.81, 33.59(CH , NCPh); MS (ESI)
2
?
m/z calcd. = 319.08, found: 320.08 [M ?H]; Anal. Calcd for
9
.05 %. Found: C, 64.34; H, 5.08; N, 7.88; S, 9.02 %.
C H N OS : C, 67.69; H, 4.10; N, 13.16; S, 10.04 %. Found:
18 13 3
3
-Benzyl-5-(4-fluorobenzylidene)-2-thioxoimidazolidin-4-
C, 67.64; H, 4.04; N, 13.11; S, 10.00 %.
one (IIId)
3-((1-Benzyl-5-oxo-2-thioxoimidazolidin-4-
Pale yellow solid; Yield = 90 %; m.p. 195-197 °C; IR
ylidene)methyl)benzonitrile (IIIg)
-
1
(
KBr, cm ) t
= 3448, 3064, 2803, 1716, 1596, 1508,
max
1
1
1
2
4
1
1
1
1
224, 1172; H NMR (400 MHz, DMSO-d ) d: 11.83 (s,
H, NH), 8.28–8.24 (m, 2H, Ar–H), 7.50 (d, J = 8.0 Hz,
Yellow solid; Yield = 93 %; m.p. 203–205 °C; IR (KBr,
6
-
1
cm ) t
= 3433, 3126, 2925, 2233, 1717, 1639, 1500,
max
1
H, Ar–H), 7.35-7.23 (m, 5H, Ar–H), 6.76 (s, 1H, CH),
1
1187; H NMR (400 MHz, DMSO-d ) d: 11.96 (s, 1H, NH),
6
3
.55 (s, 2H, CH2); C NMR (100 MHz, DMSO-d ) d:
8.65 (s, 1H, Ar–H), 8.44–8.42 (m, 1H, Ar–H), 7.81–7.89 (m,
1H, Ar–H), 7.65–7.61 (m, 1H, Ar–H), 7.53–7.51 (m, 2H,
Ar–H), 7.36–7.33 (m, 2H, Ar–H), 7.27–7.24 (m, 1H, Ar–H),
6
70.47(C, C=S), 164.14(C, C=O), 163.84(CF, C Ar),
4
61.36(CF, C Ar), 138.84(C, C CNH), 137.09(C, C Ph),
1
4
5,
1
3
33.78(CH, C Ar), 133.71(CH, C Ar), 130.94(C, C Ar),
2
6.76 (s, 1H, CH), 4.55 (s, 2H, CH2); C NMR (100 MHz,
6
1
29.04, 128.55, 127.49, 119.87(CH, C–Ar), 115.85(CH,
DMSO-d ) d: 170.16(C, C=S), 166.07(C, C=O), 140.64(C,
6
1
23

Med Chem Res
C NH), 137.10(C, C Ph), 135.58(C, C Ar), 135.50(CH,
1
7.33–7.29 (m, 5H, Ar–H), 7.28–7.23 (m, 3H, Ar–H), 6.10
1
1
1
(s, 1H, CH), 4.40 (s, 4H, CH2); C NMR (100 MHz,
3
C Ar), 134.22(CH, C Ar), 132.30(CH, C Ar), 129.85(CH,
2
4
6
C Ar), 128.98(CH, C Ar & CH, C Ar), 128.52(CH, C Ph &
5
DMSO-d ) d: 166.34(C, C=S), 159.46(C, C=O), 149.47(C-
3
5
2
6
CH, C Ph), 127.47(CH, C4Ph), 118.58(C, C:N),
NO , C Ar), 145.67(CH, C-CAr), 137.07(C, C Ar),
1
6
2
4
1
18.00(CH, C–Ar), 111.81(C, C Ar), 33.53(CH , NCPh,);
3
130.67(CH, C=CAr), 129.19(CH, C Ph & CH, C Ph),
3 5
2
?
MS (ESI) m/z calcd. = 319.08, found: 320.08 [M ?H];
128.58(CH, C Ph & CH, C Ph), 127.99(CH, CAr),
2 6
Anal. Calcd for C H N OS : C, 67.69; H, 4.10; N, 13.16;
1
127.45(CH, C Ph), 123.56(CH, CAr), 123.30(CH, CAr),
4
8
13
3
S, 10.04 %. Found: C, 67.62; H, 4.07; N, 13.10; S, 9.98 %.
98.91(C, C = CAr), 33.47(CH2, NCPh), 32.87(CH2,
NCPh); MS (ESI) m/z calcd. = 457.11, found: 458.14
?
M ?H]; Anal. Calcd for C H N O S : C, 65.63; H,
[
2
5 19 3 4
3
-Benzyl-5-(4-(dimethylamino)benzylidene)-2-
2
thioxoimidazolidin-4-one (IIIh)
4.19; N, 9.18; S, 7.01 %. Found: C, 65.60; H, 4.14; N, 9.13;
S, 6.99 %.
6
Orange solid; Yield = 92 %; m.p. 195–200 °C; IR (KBr,
-
1
cm ) tmax = 3435, 3005, 2820, 1692, 1586, 1525, 1433,
1,3-Dibenzyl-5-(4-fluorobenzylidene)-2-
1
1
367, 1163; H NMR (400 MHz, DMSO-d ) d: 11.55 (s, 1H,
thioxodihydropyrimidine-4,6(1H,5H)-dione (IVb)
6
NH), 8.05 (d, J = 8.8 Hz, 2H, Ar–H), 7.50 (d, J = 7.3 Hz,
H, Ar–H), 7.35–7.31 (m, 2H, Ar–H), 7.27–7.23 (m, 1H, Ar–
H), 6.75 (d, J = 8.8 Hz, 2H, Ar–H), 6.67 (s, 1H, CH), 4.53
2
Colorless solid; Yield = 88 %; m.p. 255–257 °C (d); IR
-
1
(KBr, cm ) tmax = 3027, 2926, 2853, 1623, 1552, 1507,
1407, 1296, 1227, 1065; H NMR (400 MHz, DMSO-d )
1
3
1
(
s, 2H, CH ), 2.99 (s, 6H, N-CH ); C NMR (100 MHz,
2
3
6
DMSO-d ) d: 170.52(C, C=S), 159.27(C, C=O), 151.10(C,
d: 7.32 (d, J = 7.3 Hz, 4H, Ar–H), 7.31 (t, J = 7.3 Hz,
4H, Ar–H), 7.27–7.23 (m, 2H, Ar–H), 7.05–7.00 (m, 4H,
6
C Ar), 137.42(C, C NH), 135.24(C, C Ph), 133.39,
4
5
1
1
Ar–H), 6.02 (s, 1H, CH), 4.39 (s, 4H, CH2); C NMR
3
1
29.03(CH, C Ar & CH, C Ar), 128.55(CH, C Ph & CH,
3
2
6
C Ph), 127.44(CH, C Ph), 123.21(C, C Ar), 121.70(CH,
5
(100 MHz, DMSO-d ) d: 166.36(C, C=S), 161.64(C–F,
4
1
6
C Ar & C Ar), 111.71(C, C–Ar), 33.23(CH , NCPh); Anal.
2
CAr) 159.24(C, C=O), 137.07(C, C Ph), 136.18(CH,
1
3
5
Calcd for C H N OS : C, 67.63; H, 5.68; N, 12.45; S,
1
C=CAr), 129.15(CH, C Ph & CH, C Ph), 128.54(CH,
3
9
19
3
5
9
.50 %. Found: C, 67.58; H, 5.63; N, 12.44; S, 9.47 %.
C Ph & CH, C Ph), 128.34(CH, CAr), 128.26(CH, CAr),
2 6
127.40(CH, C Ph), 114.76(CH, CAr), 114.55(CH, CAr),
4
9
9.62(C, C=CAr), 33.41(CH , NCPh), 31.50(CH , NCPh);
2
2
?
MS (ESI) m/z calcd. = 430.12, found: 431.14 [M ?H];
General procedure for the synthesis of 1,3-dibenzyl-5-
arylidene-2-thioxodihydropyrimidine-4,6(1H,5H)-
diones (IVa–i)
Anal. Calcd for C H FN O S : C, 69.75; H, 4.45; F, 4.41;
2
5
19
2 2
N, 6.51; S, 7.45 %. Found: C, 69.70; H, 4.39; F, 4.38; N,
.44; S, 7.42 %.
6
In a typical reaction, a mixture of aromatic aldehyde (1.0
equiv.), 2-thiobarbituric acid (1.0 equiv.), benzyl bromide (2.0
equiv.), and Ni nanoparticles dispersion in ethylene glycol
1,3-Dibenzyl-5-(3-nitrobenzylidene)-2-
[2.0 mL of dispersion (0.0235 wt% of Ni)/0.1 g aldehyde] was
thioxodihydropyrimidine-4,6(1H,5H)-dione (IVc)
stirred thoroughly in a 50 mL R. B. flask maintained at 70 °C.
The reaction progress was monitored by thin column chro-
matography (TLC), using petroleum ether/ethyl acetate
Colorless solid; Yield = 90 %; m.p. 225–227 °C; IR (KBr,
-1
1
= 2924, 1624, 1560, 1420, 1350, 1300, 1094; H
cm ) t
max
(60:40)aseluent.Uponcompletion,15 mLofwaterwasadded
NMR (400 MHz, DMSO-d ) d: 8.03 (d, J = 7.3 Hz, 1H, Ar–
6
to the reaction mixture, and the solid product was filtered at
pump, washed with water, dried, and recrystallized from hot
ethanol. The products were identified by spectral data.
H), 7.77 (s, 1H, Ar–H), 7.55–7.49 (m, 2H, Ar–H), 7.44 (d,
J = 6.6 Hz, 4H, Ar–H), 7.33–7.23 (m, 6H, Ar–H), 6.07 (s,
1
1H, CH), 4.40 (s, 4H, CH ); C NMR (100 MHz, DMSO-d )
3
2
6
d: 166.24(C, C=S), 166.03, 147.81(C-NO2, C Ar),
4
143.39(CH, C-CAr), 137.06(CH, C=CAr), 133.93(C CAr),
1,
1
,3-Dibenzyl-5-(4-nitrobenzylidene)-2-
129.61(CH, C Ph & CH, C Ph), 129.18(CH, C Ph & CH,
3 5 2
thioxodihydropyrimidine-4,6(1H,5H)-dione (IVa)
C Ph), 128.57(CH, CAr), 127.44(CH, CAr), 121.08(CH,
6
CAr), 120.88(CH, CAr), 98.76(C, C=CAr), 33.46(CH2,
Colorless solid; Yield = 92 %; m.p. 245–247 °C; IR (KBr,
NCPh), 30.71; MS (ESI) m/z calcd. = 457.11, found: 458.14
?
[M ?H]; Anal. Calcd for C H N O S : C, 65.63; H, 4.19;
-
1
cm ) tmax = 2909, 1627, 1548, 1515, 1419, 1345, 1302,
25
19 3 4
1
1
232, 1096; H NMR (400 MHz, DMSO-d ) d: 8.09 (d,
N, 9.18; S, 7.01 %. Found: C, 65.57; H, 4.12; N, 9.15; S,
6.97 %.
6
J = 8.0 Hz, 2H, Ar–H), 7.45–7.43 (m, 4H, Ar–H),
123

Med Chem Res
1
,3-Dibenzyl-5-(2,5-dimethoxybenzylidene)-2-
CAr), 99.52(C, C=CAr), 33.40(CH , NCPh), 31.55,
2
thioxodihydropyrimidine-4,6(1H,5H)-dione (IVd)
19.01(CH , C(Me)); MS (ESI) m/z calcd. = 426.14, found:
3
?
27.16 [M ?H]; Anal. Calcd for C H N O S : C, 73.21;
4
2
6 22 2 2
Yellow solid; Yield = 89 %; m.p. 150–152 °C; IR (KBr,
H, 5.20; N, 6.57; S, 7.52 %. Found: C, 73.16; H, 5.13; N,
6.49; S, 7.47 %.
-
1
cm ) tmax = 2929, 1624, 1560, 1495, 1424, 1293, 1225;
1
H NMR (400 MHz, DMSO-d ) d: 7.42 (d, J = 7.3 Hz,
6
4
H, Ar–H), 7.32–7.28 (m, 4H, Ar–H), 7.26–7.22 (m, 2H,
1,3-Dibenzyl-5-(2-nitrobenzylidene)-2-
Ar–H), 6.76 (d, J = 8.7 Hz, 1H, Ar–H), 6.69–6.66 (m, 1H,
thioxodihydropyrimidine-4,6(1H,5H)-dione (IVg)
Ar–H), 6.54–6.53 (m, 1H, Ar–H), 5.95 (s, 1H, CH), 4.37 (s,
1
H, CH ), 3.61 (s, 3H, OMe), 3.49 (s, 3H, OMe); C NMR
3
4
Colorless solid; Yield = 90 %; m.p. 220–224 °C; IR (KBr,
2
-
1
(
100 MHz, DMSO-d ) d: 152.66(C, COMe), 151.47 (C,
cm ) t
= 3061, 1653, 1545, 1395, 1363, 1286, 1240,
6
max
1
COMe), 137.32(C, C Ph), 130.78, 129.12(CH, C Ph & CH,
1
1063; H NMR (400 MHz, DMSO-d ) d: 7.67 (d,
3
6
C Ph), 128.52(CH, C Ph & CH, C Ph), 127.38 (CH, C Ph),
5
J = 6.6 Hz, 1H, Ar–H), 7.53–7.49 (m, 1H, Ar–H), 7.42 (d,
J = 7.3 Hz, 4H, Ar–H), 7.39–7.35 (m, 1H, Ar–H), 7.31 (t,
J = 7.3 Hz, 4H, Ar–H), 7.26-7.22 (m, 3H, Ar–H), 6.21 (s,
2
6
4
1
9
3
16.03 (CH, CAr), 111.79 (CH, CAr), 109.74(CH, CAr),
9.69(C, C=CAr), 56.10(CH , OMe), 55.10(CH , OMe),
3
3
1
3
3.36 (CH , NCPh), 30.69(CH , NCPh); MS (ESI) m/z
2
1H, CH), 4.36 (s, 4H, CH2); C NMR (100 MHz, DMSO-
d6) d: 206.48(C, C=S), 165.47(C, C=O), 149.50(CH,
C-CAr), 137.20(C-NO , C Ar), 135.08(C , CPh), 131.88,
2
?
calcd. = 472.15, found: 473.13 [M ?H]; Anal. Calcd for
C H N O S : C, 68.62; H, 5.12; N, 5.93; S, 6.79 %.
4
2
7
24
2
2
2
1
Found: C, 68.59; H, 5.10; N, 5.88; S, 6.75 %.
129.81(CH, C Ph & CH, C Ph), 129.14(CH, C Ph & CH,
3 5 2
C Ph), 128.53(CH, CAr), 127.38(CH, C Ph), 126.97(CH,
6
4
1
,3-Dibenzyl-5-(4-isopropylbenzylidene)-2-
CAr), 123.77(CH, CAr), 98.03(C, C=CAr), 33.35(CH2,
NCPh), 30.70(CH2, NCPh); MS (ESI) m/z
?
calcd. = 457.11, found: 458.12 [M ?H]; Anal. Calcd for
thioxodihydropyrimidine-4,6(1H,5H)-dione (IVe)
Colorless solid; Yield = 89 %; m.p. 250 °C (d); IR (KBr,
C H N O S : C, 65.63; H, 4.19; N, 9.18; S, 7.01 %.
25 19 3 4
-1
1
= 2926, 1624, 1560, 1411, 1295, 1266, 1068; H
cm ) t
Found: C, 65.59; H, 4.16; N, 9.11; S, 6.97 %.
max
NMR (400 MHz, DMSO-d ) d: 7.43 (d, J = 7.3 Hz, 4H, Ar–
6
H), 7.33–7.29 (m, 4H, Ar–H), 7.27–7.23 (m, 2H, Ar–H), 7.07
1,3-Dibenzyl-5-(naphthalen-2-ylmethylene)-2-
(
d, J = 8.0 Hz, 2H, Ar–H), 6.89 (d, J = 7.3 Hz, 2H, Ar–H),
thioxodihydropyrimidine-4,6(1H,5H)-dione (IVh)
6
.02 (s, 1H, CH), 4.39 (s, 4H, CH ), 2.84-2.76 (m, 1H, CH),
2
1
.15 (d, J = 7.3 Hz, 6H, CH3); C NMR (100 MHz,
3
1
Colorless solid; Yield = 87 %; m.p. 205–207 °C; IR (KBr,
-
1
DMSO-d ) d: 166.53(C, C=S), 158.78(C, C=O), 145.41(CH,
C-CAr), 137.42(C1, CAr), 137.09(C , CPh), 129.15(CH,
1
cm ) t
= 2924, 2854, 1618, 1546, 1423, 1295, 1274,
6
max
1
1220; H NMR (400 MHz, DMSO-d ) d: 7.83–7.75 (m,
6
C Ph & CH, C Ph), 128.55(CH, C Ph & CH,C Ph),
3
2H, Ar–H), 7.46–7.39 (m, 8H, Ar–H), 7.32 (t, J = 7.3 Hz,
5
2
6
1
9
3
27.41(CH, C Ph), 126.38(CH, CAr), 125.97(CH, CAr),
4
4H, Ar–H), 7.28–7.24 (m, 2H, Ar–H), 7.18 (d, J = 8.8 Hz,
1
1H, Ar–H), 6.21 (s, 1H, CH), 4.42 (s, 4H, CH2); C NMR
3
9.81(C, C=CAr), 33.43(CH , NCPh), 32.93(CH , NCPh),
2
2
1.59(CH, CH(Me) ), 23.96(CH , CH(Me) ); MS (ESI) m/z
2
(100 MHz, DMSO-d ) d: 166.60(C, C=S), 158.93(C, C=O)
3
2
6
?
calcd. = 454.17, found: 455.19 [M ?H]; Anal. Calcd for
137.96(CH, C-CAr), 137.09(C, C Ph), 133.02(C, CNp),
1
C H N O S : C, 73.98; H, 5.76; N, 6.16; S, 7.05 %. Found:
2
131.57(C, CNp), 129.17(CH, C Ph & C Ph), 128.56(CH,
3
8
26
2
2
5
C, 73.92; H, 5.73; N, 6.12; S, 6.99 %.
C Ph & C Ph), 127.55(C, CNp), 127.42(CH, C Ph),
2 6 4
127.25(C, CNp), 125.85(C, CNp), 125.20(C, CNp),
1
,3-Dibenzyl-5-(2-methylbenzylidene)-2-
124.17(C, CNp), 99.69(C, C=CAr), 33.46(CH , NCPh),
2
thioxodihydropyrimidine-4,6(1H,5H)-dione (IVf)
32.40(CH , NCPh); MS (ESI) m/z calcd. = 462.14, found:
2
?
63.13 [M ?H]; Anal. Calcd for C H N O S : C, 75.30;
4
2
9 22 2 2
Colorless solid; Yield = 91 %; m.p. 248–250 °C (d); IR
H, 4.79; N, 6.06; S, 6.93 %. Found: C, 75.27; H, 4.71; N,
6.02; S, 6.90 %.
-
1
(
KBr, cm ) tmax = 2927, 1610, 1549, 1420, 1284, 1237,
1
1
066; H NMR (400 MHz, DMSO-d ) d: 7.42 (d,
6
J = 7.3 Hz, 4H, Ar–H), 7.32–7.23 (m, 6H, Ar–H), 7.03 (s,
1,3-Dibenzyl-5-(3-chlorobenzylidene)-2-
4
H, Ar–H), 5.86 (s, 1H, CH), 4.37 (s, 4H, CH ), 2.00 (s,
2
thioxodihydropyrimidine-4,6(1H,5H)-dione (IVi)
1
3
3
H, CH3); C NMR (100 MHz, DMSO-d ) d: 166.43(C,
6
C=S), 166.02(C, C=O), 139.47(CH, C-CAr), 137.14(C1,
Colorless solid; Yield = 92 %; m.p. 240 °C (d); IR (KBr,
-
1
CPh), 135.50(C , CAr), 130.16(C, CAr), 129.12(CH, C Ph
3
cm ) t
= 2924, 2854, 1618, 1546, 1423, 1295, 1274,
1
max
1
&
CH, C Ph), 128.51(CH, C Ph & CH, C Ph), 127.78(CH,
5
1220; H NMR (400 MHz, DMSO-d ) d: 7.44 (d,
2
6
6
CAr), 127.38(CH, C Ph), 125.65(CH, CAr), 125.17(CH,
4
J = 7.3 Hz, 4H, Ar–H), 7.31 (t, J = 7.3 Hz, 4H, Ar–H),
1
23

Med Chem Res
6
7
.27–7.19 (m, 4H, Ar–H), 6.97 (s, 2H, Ar–H), 6.03 (s, 1H,
already seeded with 100 lL of standardized inoculum (10
1
CH), 4.40 (s, 4H, CH2); C NMR (100 MHz, DMSO-d6)
3
cfu/mL) of the test microbial strain. All test plates were
incubated aerobically at 37 °C for 24 h and observed for
the inhibition zones. MIC, taken as the lowest concentra-
tion of the chemical compound that completely inhibited
the growth of the microbe, showed by a clear zone of
inhibition, was recorded for each test organism. Cipro-
floxacin was used as positive control.
d: 166.48(C, C=S), 159.04(C, C=O), 143.23(CH, C-CAr),
1
37.04(C, C Ph), 132.84(C–Cl, C Ar), 129.94(C, C Ar),
1 3 1
1
29.17(CH, C Ph & CH, C Ph), 128.55(CH, C Ph & CH,
2
3
5
C Ph), 127.43(CH, C Ph), 126.21(CH, CAr), 125.64(CH,
6
4
CAr), 125.48(CH, CAr), 99.11(C, C=CAr), 33.46 (CH2,
NCPh), 32.07(CH , NCPh); MS (ESI) m/z calcd. =
2
?
46.09, found: 447.09 [M ?H]; Anal. Calcd for
4
C H ClN O S : C, 67.18; H, 4.28; Cl, 7.93; N, 6.27; S,
2
Antifungal activity
5
19
2 2
7
7
.17 %. Found: C, 67.09; H, 4.23; Cl, 7.89; N, 6.21; S,
.14 %.
The antifungal activity of 16 compounds was evaluated by
poisoned food technique (Al- Burtamani et al., 2005). The
molds were grown on Sabouraud dextrose agar (SDA) at
Anti-microbial assay
25 °C for 7 days and used as inocula. The 15 mL of molten
Antibacterial activity
SDA (45 °C) was poisoned by the addition of 100 lL
volume of each compound having concentration of 2.0 mg/
mL reconstituted in the DMSO, poured into a sterile Petri
plate and allowed it to solidify at room temperature. The
solidified poisoned agar plates were inoculated at the center
with fungal plugs (8 mm diameter) obtained from the
colony margins and incubated at 25 °C for 7 days. DMSO
was used as the negative control whereas Fluconazole was
used as the positive control. The experiments were per-
formed in triplicates. Diameter of fungal colonies was
measured and expressed as percent mycelial inhibition.
The antibacterial activity of 16 compounds was evaluated
by the agar well diffusion method. All the microbial cul-
tures were adjusted to 0.5 McFarland standard, which is
visually comparable to a microbial suspension of approx-
6
imately 1.5 9 10 cfu/mL. 20 mL of Mueller–Hinton agar
medium was poured into each Petri plate, and plates were
swabbed with 100 lL inocula of the test microorganisms
and kept for 15 min for adsorption. Using sterile cork borer
of 8-mm diameter, wells were bored into the seeded agar
plates and these were loaded with a 100 lL volume with
concentration of 2.0 mg/mL of each compound reconsti-
tuted in the dimethylsulfoxide (DMSO). All the plates were
incubated at 37 °C for 24 h. Antibacterial activity of each
compound was evaluated by measuring the zone of growth
inhibition against the test organisms with zone reader
Percent inhibition of myelial growth
¼
ðdc ꢁ dtÞ=dc ꢂ 100;
dc = average diameter of fungal colony in negative control,
setsdt = average diameter fungal colony in experimental
sets.
(
HiAntibiotic zone scale). DMSO was used as a negative
Acknowledgments Sneha is thankful to CSIR, New Delhi, India for
the award of Junior and Senior Research Fellowship.
control whereas Ciprofloxacin was used as positive control.
This procedure was performed in three replicate plates for
each organism, and the mean values of the diameter of
inhibition zones ± standard deviations were calculated
References
(
Aneja et al., 2011).
Agasimundin YS, Mumper MW, Hasmane RS (1998) Inhibitors of
glycogen phosphorylase B: synthesis, biochemical screening,
and molecular modeling studies of novel analogues of hydant-
ocidin. Bioorg Med Chem 6:911–923
Determination of minimum inhibitory concentration (MIC)
of chemical compounds
Al- Burtamani SKS, Fatope MO, Marwah RG, Onifade AK, Al-Saidi
SH (2005) Chemical composition, antibacterial and antifungal
activities of the essential oil of Haplophyllum tuberculatum.
J Ethnopharmocol 96:107–112
Aly YL, El-Barbary AA, El-Shehawya AA (2004) Alkylation of
thiohydantoins including synthesis, conformational and config-
urational studies of some acetylated S-pyranosides. Phosphorus
Sulfur Silicon Relat Elem 179:185–202
Aneja KR, Sharma C, Joshi R (2011) In vitro efficacy of amaltas
(Cassia fistula L.) against the pathogens causing otitis externa.
J Microbiol 4:175–183
Bojarski JT, Mokros JL, Barton HJ, Paluchowska MH (1985) Recent
progress in barbituric acid chemistry. Adv Heterocycl Chem
38:229–297
MIC is the lowest concentration of an anti-microbial
compound that will inhibit the visible growth of a micro-
organism after overnight incubation. MIC of the various
compounds against bacterial strains was tested through a
modified agar well diffusion method (Aneja et al., 2011).
In this method, a two-fold serial dilution of each chemi-
cally synthesized compound was prepared by first recon-
stituting the compound in DMSO followed by dilution in
sterile distilled water to achieve a decreasing concentration
range of 512–1 lg/mL. A 100 lL volume of each dilution
was introduced into wells (in triplicate) in the agar plates
123

Med Chem Res
Chui W-K, Wong T-H, Thenomozhiyal JC (2004) Anticonvulsant
activity of phenylmethylenehydantoins:
relation study. J Med Chem 47:1527–1535
Figueroa-Villar JD, Rangel CE, Dos Santos LN (1992) Synthesis of
oxadeazaflavines from barbituric acid and aromatic aldehydes.
Synth Commun 22:1159–1164
Kie c´ -Kononowicz K, Szyma n´ ska E (2002) Antimycobacterial activity
of 5-arylidene derivatives of hydantoin. Farmaco 57:909–916
Mizuno T, Kino T, Ito T, Miyata T (2000) Synthesis of aromatic urea
herbicides by the selenium-assisted carbonylation using carbon
monoxide with sulfur. Synth Commun 30:1675–1688
Muccioli GG, Fazio N, Scriba GKE, Poppitz W, Cannata F, Poupaert
JH, Wouters J, Lambert DM (2006) Substituted 2-thioxoimidaz-
olidin-4-ones and imidazolidine-2,4-diones as fatty acid amide
hydrolase inhibitors templates. J Med Chem 49:417–425
Ono M, Hayashi S, Matsumura K, Kimura H, Okamoto Y, Ihara M,
Takahashi R, Mori H, Saji H (2011) Rhodanine and thiohydan-
toin derivatives for detecting tau pathology in alzheimer’s brains.
ACS Chem Neurosci 2:269–275
a structure-activity
Frangin Y, Guimbal C, Wissocq F, Zamarlik H (1986) Synthesis of
substituted barbituric acids via organozinc reagents. Synthesis
1
986:1046–1050
Gadwood RC, Kamdar BV, Dubray LAC, Wolfe ML, Smith MP,
Watt W, Mizsak SA, Groppi VE (1993) Synthesis and biological
activity of spirocyclic benzopyran imidazolone potassium chan-
nel openers. J Med Chem 36:1480–1487
Gulati D, Chauhan PMS, Pratap R, Bhakuni DS (1994) A new
synthesis of 5-bromoaplysinopsin, 6-bromoaplysinopsin and 3’-
demethylaplysinopsin and their biological activities. Ind J Chem
Shih RU, Wu J, Liu Y, Liang YC, Lin SY, Sheu MT, Lee WS (2004)
Anti-proliferation effect of 5,5-diphenyl-2-thiohydantoin
(DPTH) in human vascular endothelial cells. Biochem Pharma-
col 67:67–75
3
3B:10–16
Handzlik J, Spengler G, Mastek B, Dela A, Molnar J, Amaral L, Kie c´ -
Kononowicz K (2012) 5-Arylidene(thio)hydantoin derivatives as
modulators of cancer efflux pump. Acta Poloniae Pharmaceutica
Drug Research 69:149–153
Spengler G, Evaristo M, Handzlik J, Serly J, Molnꢀr J, Viveiros M,
ˆ
KieE-Kononowicz K, Amaral L (2010) Biological activity of
hydantoin derivatives on P-glycoprotein (ABCB1) of mouse
lymphoma cells. Anticancer Res 30:4867–4871
He S, Kuang R, Venkataraman R, Tu J, Truong TM, Chan HT,
Groutas WC (2000) Potent inhibition of serine proteases by
heterocyclic sulfide derivatives of 1,2,5-thiadiazolidin-3-one-
Szyma n´ ska E, Kie c´ -Kononowicz K, Białecka A, Kasprowicz A
(2002) Antimicrobial activity of 5- arylidene aromatic deriva-
tives of hydantoin. Farmaco 57:39–44
1
,1-dioxide. Bioorg Med Chem 8:1713–1717
Kandra L, Remenyik J, Batta G, Soms a´ k L, Gy e´ m a´ nt G, Park KH
2005) Enzymatic synthesis of a new inhibitor of a-amylases:
acarviosinyl-isomaltosyl-spiro-thiohydantoin. Carbohydr Res
40:1311–1317
Takahashi A, Matsuoka H, Yamada K, Uda Y (2005) Characteriza-
tion of antimutagenic mechanism of 3-allyl-5-substituted 2-thi-
ohydantoins against 2-amino-3-methylimidazo[4,5-f]quinoline.
Food Chem Toxicol 43:521–528
Tanaka K, Cheng X, Yoneda F (1988) Oxidation of thiol with
5arylidene-1,3-dimethylbarbituric acid: application to synthesis
of unsymmetrical disulfide. Tetrahedron 44:3241–3249
Tompkin JE (1986) 5,5-Diaryl-2-thiohydantoins and 5,5-diaryl-N3-
substituted-2-thiohydantoins as potential hypolipidemic agents.
J Med Chem 29:855–859
(
3
Khurana JM, Sneha, Vij K (2012) Ni nanoparticles: mild and efficient
catalyst for the chemoselective synthesis of 2-arylbenzimidaz-
oles, 2-arylbenzothiazoles and azomethines. Synth Commun
4
2:2606–2616
Khurana JM, Vij K (2010) Nickel nanoparticles catalyzed knoeve-
nagel condensation of aromatic aldehydes with barbituric acids
and 2-thiobarbituric acids. Catal Lett 138:104–110
Khurana JM, Vij K (2011) Nickel nanoparticles catalyzed chemose-
lective knoevenagel condensation of meldrum’s acid and tandem
enol lactonizations via cascade cyclization sequence. Tetrahe-
dron Lett 52:3666–3669
Yan Q, Cao R, Yi W, Chen Z, Wen H, Ma L, Song H (2009)
Inhibitory effects of 5-benzylidene barbiturate derivatives on
mushroom tyrosinase and their antibacterial activities. Eur J Med
Chem 44:4235–4243
1
23