Click chemistry inspired synthesis of piperazine-triazole derivatives and evaluation of their antimicrobial activities

Article abstract of DOI:10.1007/s00044-015-1361-5

A series of novel piperazine-1,2,3-triazole derivatives, which entailed the bioisosteric replacement of the imidazole moiety and hybridization of two drug scaffolds was prepared by employing the regioselective copper (I)-catalysed azide-alkyne 1,3-dipolar cycloaddition reaction. The synthesized compounds were evaluated for antibacterial activities against Gram-negative (E. Coli and P. Putida), Gram-positive S. Aureus bacteria and fungicidal activities against F. oxysporum, F. gramillarium and F. monalliforme fungi. Compound 7ac′ exhibited moderate but promising antibacterial activity against Gram-negative bacteria and fungicidal activity against F. oxysporum and F. gramillarium.

Full text of DOI:10.1007/s00044-015-1361-5

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-015-1361-5
ORIGINAL RESEARCH
Click chemistry inspired synthesis of piperazine-triazole
derivatives and evaluation of their antimicrobial activities
Poonam Khedar1 Kasiviswanadharaju Pericherla1
•
•
Rajnish Prakash Singh2 Prabhat Nath Jha2 Anil Kumar1
•
•
Received: 17 June 2014 / Accepted: 10 March 2015
Ó Springer Science+Business Media New York 2015
Abstract A series of novel piperazine-1,2,3-triazole
derivatives, which entailed the bioisosteric replacement of
the imidazole moiety and hybridization of two drug scaf-
folds was prepared by employing the regioselective copper
(I)-catalysed azide-alkyne 1,3-dipolar cycloaddition reac-
tion. The synthesized compounds were evaluated for an-
tibacterial activities against Gram-negative (E. Coli and P.
Putida), Gram-positive S. Aureus bacteria and fungicidal
activities against F. oxysporum, F. gramillarium and F.
monalliforme fungi. Compound 7ac0 exhibited moderate
but promising antibacterial activity against Gram-negative
bacteria and fungicidal activity against F. oxysporum and
F. gramillarium.
(Karyotakis and Anaissie, 1994). Piperazine is also found
along with azoles moieties in several antifungal drugs such
as itraconazole and ketoconazole. In recent years, 1,2,3-
triazoles gained the interest owing to their broad range of
biological activities such as anti-HIV (Alvarez et al.,
1994), anti-inflammatory (de Oliveira Assis et al., 2012),
anti-malarial (Manohar et al., 2011), anti-viral (Ferreira
et al., 2014), and anticancer activities (Kamal et al., 2008;
Yan et al., 2010). Particularly, these aza-heterocyclic mo-
tifs were widely studied as antifungal agents due to their
low toxicity and broad antifungal spectrum (Agalave et al.,
2011; Jiang et al., 2011; Pore et al., 2012). Moderate dipole
character, rigidity, and hydrogen-bonding ability and sta-
bility under different conditions are some important prop-
erties of 1,2,3-triazoles responsible for their enhanced
biological activities (Horne et al., 2004; Kolb and Sharp-
less, 2003; Wang et al., 2010).
Keywords 1,2,3-Triazole ꢀ Click chemistry ꢀ
Antimicrobial activity ꢀ Bioisosteres
The growing emergence of antimicrobial resistance,
especially in the field of multidrug-resistant bacteria and
fungi, are major concerns to the public health. In the view
of high incidence of fungal infections in immune com-
promised patients, there is a continuing demand for safe
and effective broad spectrum antifungal agents with
favourable pharmacokinetic properties. Hence, there is an
urgent need for the development of structurally new classes
of antimicrobials.
Introduction
Azoles are the most widely used antifungal drugs for sys-
temic fungal infections (Genin et al., 2000; Sheehan et al.,
1999; Sheng et al., 2006). The first antifungal azoles were
imidazoles such as econazole, miconazole, isoconazole,
and ketoconazole (Fig. 1). 1,2,4-Triazole antibiotics such
as fluconazole and itraconazole are less toxic than imida-
zole derivatives and have broad spectrum activity
The bioisosteric replacement of imidazole and 1,2,4-
triazole is an efficient concept for the discovery and de-
velopment of novel drug molecules possessing enhanced
antifungal or antibacterial activity (Gu¨ven et al., 2007;
Marrapu et al., 2011; Wahbi et al., 1995). Fluconazole is
also a bioisostere of these drugs recommended as first-line
& Anil Kumar
anilkumar@pilani.bits-pilani.ac.in
1
Department of Chemistry, Birla Institute of Technology and
Science, Pilani 333031, Rajasthan, India
¨
antifungal drug by World Health Organization (Domling
2
et al., 2012). Another approach for generating novel drug
Department of Biological Sciences, Birla Institute of
Technology and Science, Pilani 333031, Rajasthan, India
molecules is the fusion of two or more pharmacophores in
123

Med Chem Res
Cl
Cl
O
Cl
Cl
O
N
N
N
OH
N
O
Cl
Cl
N
N
N
N
N
N
N
F
Cl
Cl
N
F
Cl
Miconazole
Cl
Cl
Isoconazole
Econazole
Fluconazole
N
N
N
N
N
O
Cl
Cl
O
O
O
N
N
O
N
N
O
N
N
N
O
O
Cl
H
Cl
Ketoconazole
Fig. 1 Structure of some antifungal azoles
Itraconazole
a single molecular framework. In this context, copper-
catalysed azide–alkyne 1,3-dipolar cycloaddition (CuAAC)
‘click reaction’ is one of the most reliable and straight-
forward way for conjugation of two pharmacophores (Hou
et al., 2012; Kolb et al., 2001). The 1,2,3-triazoles have
been effectively used as an attractive linker to connect two
pharmacophores to give an innovative bifunctional drug.
The triazole group of the click reaction not only is a linker
but also interacts with biological targets, through hydrogen
bonding and dipole interactions, and thus imparts synergic
effect to biological activities (Holub and Kirshenbaum,
2010; Willand et al., 2010).
hybridization of piperazine and alkoxy units. Herein, we
wish to report the synthesis and antimicrobial activities of
some novel piperazine-triazole derivatives.
Results and discussion
Chemistry
Synthetic route for the targeted 1,2,3-triazoles (7a–o) is
outlined in Scheme 1. a-Haloketones (1a–f) were prepared
by reacting acetophenones with N-bromosuccinimide in the
presence of p-toluenesulphonic acid.(Pericherla et al.,
2012) These phenacyl bromides (1a–f) were treated with
NaN3 to afford 2-azido-1-phenylethanones (2a–f). The
azide substitution is a straightforward reaction with ex-
cellent yields, and they were reduced by NaBH4 to give
corresponding alcohols (3a–f). The high purity of reduced
products (3a–f) after regular work-up allowed us to move
Inspired by the click chemistry and prompted by the
chemotherapeutic importance of 1,2,3-triazoles as bioi-
sostere of imidazole and hybridization approach, we en-
visioned the synthesis of novel piperazine-triazole
derivatives as antimicrobial agents (Fig. 2). A key feature
of our designed strategy is the replacement of imidazole or
1,2,4-triazole with bioisostere 1,2,3-triazole unit and
Cl
N
N
Hybridization
Cl
N
O
O
Cl
N
Cl
O
N
N
O
N
O
Cl
Cl
O
H
N
N
N
Cl
Cl
N
Ketoconazole
bioisostere replacement
Cl
Cl
Miconazole
Fig. 2 Rational for design of piperazine-triazole derivatives
123

Med Chem Res
R2
Br
R2
O
O
HO
N3
Br
O
N3
N3
i
ii
4a'-d'
iii
R1
R1
R1
a': R2 = H,
b' R2 = 4-Cl
a: R1 = H
b: R1 = 4-F
c: R1 = 2,4-diF
d: R1 = 4-Cl
e: R1 = 2,4-diCl
f: R1 = 4-Br
1a-f
2a-f
3a-f
R1
5a-o
c': R2 = 2-Cl, 4-F
d': R2 =4-Br, 2-F
R2
R2
O
N
iv
N
O
N
N
N3
N
N
+
N
R1
R1
6
5a-o
Scheme 1 Synthesis of piperazine-triazole derivatives. (i) NaN3, DMF, 25–30 °C, 12 h. (ii) NaBH4, MeOH, 0–25 °C, 2 h. (iii) NaH, DMF,
0–25 °C, 2 h. (iv) CuI, H2O:PEG 400, 25–30 °C, 5 h
to next step without further purification. Benzylation of
these alcohols with variously substituted benzyl bromides
(4a’–d’) using sodium hydride resulted in (2-azido-1-
(benzyloxy)ethyl) benzenes (5a–o). While synthesizing an
array of azides (5a–o), it was realized that substituents of
phenyl ring on alcohols (3a–f) or benzyl bromides (4a’–d’)
not affected the yields to the great extent. Simultaneously,
propargylation of 1-phenylpiperazine was achieved by re-
acting with propargyl bromide using K2CO3 to obtain
1-phenyl-4-(prop-2-ynyl) piperazine (6) in excellent yield.
The targeted 1,2,3-triazoles (7a–o) were achieved by cop-
per-catalysed Huisgen 1,3-dipolar cycloaddition of azides
(5a–o) with alkyne (6) also known as click reaction
(Scheme 1). Copper (I) iodide smoothly catalysed the
CuAAC in presence of H2O: PEG 400 at ambient tem-
perature in 5 h. An array of compounds (7a–o) was syn-
thesized in good to excellent yields using aforementioned
synthetic route. To obviate the solubility issues for biolo-
gical screening, we have also prepared the salts of these
novel piperazine-linked 1,4-disubstituted 1,2,3-triazoles by
passing dry HCl.
piperazine protons (see ESI). 13C NMR and HRMS of these
motifs further confirmed the assigned structures.
Biological activity
The synthesized compounds 7a–o were screened for an-
tibacterial activities against Gram-negative E. coli and P.
putida, Gram-positive S. Aureus. All compounds were
evaluated at the concentrations ranging from 0.5 to 128 lg/
mL and scored for MIC as the level of growth inhibition of
the microorganisms compared with chloramphenicol. The
data of antibacterial activities are depicted in Table 2.
Compound 7c with phenyl and 4-fluoro-2-chlorobenzyloxy
group showed highest activity against both Gram-positive
and Gram-negative bacteria (Table 2, entry 3). When the
activity of their HCl salts was evaluated, activity of 7a and
7e improved and this may be due to increased solubility.
Compound 7a has both unsubstituted phenyl ring, while 7e
has a 4-fluorophenyl and phenyl ring. Compound 7d, 7g,
7i, 7j, and 7k did not show any antibacterial activity to-
wards Gram-negative or Gram-positive bacteria. Remain-
ing compounds were poorly active towards Gram-negative
and Gram-positive bacteria (Tables 1, 2).
The azole antifungal drugs in use contain halo-substi-
tuted aryl groups such as 2,4-dichloro-, 2,4-difluoro-sub-
stituted benzyl rings, and thus we mainly focused to
synthesize target molecules of halo-substituted rings. The
yields and physical data of all the synthesized compounds
are shown in Table 1. All the synthesized compounds were
Further, antifungal activity of 7a–o and its HCl salts
were evaluated against F. oxysporum, F. gramillarium and
F. Monalliforme. All the compounds were evaluated at the
concentrations ranging from 0.5 to 128 lg/mL and scored
for MIC as the level of growth inhibition of the microor-
ganisms compared with carbendazim as positive control.
The data of antibacterial activities are depicted in Table 3.
It was found that 7a was more potent among all compounds
in neutral form towards F. oxysporum and F. gramillarium,
1
well characterized by spectroscopic data such as H NMR
1
and 13C NMR. In the H NMR spectra of 7a–o a charac-
teristic, singlet peak for triazole C4-proton (C–H) appeared
at d * 7.51 along with the two triplets d * 3.18 (t,
J = 4.8 Hz, 4H) and d * 2.64 (t, J = 4.8 Hz, 4H) for
123

Med Chem Res
Table 1 Synthesis of piperazine-triazole derivatives 7
Entry
R1
R2
Product
Yielda (Purity)b (%)
1
H
H
7a
7b
7c
7d
7e
7f
89 (99.4)
88 (96.9)
96 (96.9)
89 (93.1)
78 (95.0)
73 (98.0)
80 (99.2)
81 (98.1)
72 (96.0)
99 (97.7)
98 (96.8)
63 (99.3)
81 (98.4)
68 (97.0)
67 (94.4)
2
H
4-Cl
3
H
2-Cl, 4-F
2-F, 4-Br
H
4
H
5
4-F
6
4-F
4-Cl
7
2,4-diF
2,4-diF
4-Cl
4-Cl
4-Cl
2,4-diCl
2,4-diCl
2,4-diCl
4-Br
4-Cl
7g
7h
7i
8
2-Cl, 4-F
4-Cl
9
10
11
12
13
14
15
a
2-Cl, 4-F
2-F, 4-Br
4-Cl
7j
7k
7l
2-Cl, 4-F
2-F, 4-Br
4-Cl
7m
7n
7o
Isolated yield
b
Determined by HPLC analysis using Waters Sunfire C-18 column and acetonitrile as solvent
Table 2 Antibacterial activity of 7a–o and their HCl salts
Compound
E.coli
P. putida
S. aureus
Zone of inhibition (mm) MIC (lg/ml) Zone of inhibition (mm) MIC (lg/ml) Zone of inhibition (mm) MIC (lg/ml)
7a
7b
7c
7d
7e
7f
15 (20)
15 (16)
16 (16)
128 (>64)
128 (128)
>64 (>64)
15 (20)
15 (16)
16 (16)
128 (>64)
128 (128)
>64 (>64)
14 (17)
14 (16)
14 (14)
128 (128)
128 (128)
>64 ([128)
a
a
a
–
a
–
a
a
–
–
–
–
14 (18)
128 (>64)
14 (18)
128 (>64)
14 (16)
14 (17)
128 (128)
128 (128)
15 (17)
a
–
128 (128)
a
–
15 (17)
a
–
128 (128)
a
–
a
a
–
7g
7h
7i
–
14 (17)
a
–
128 (128)
a
–
14 (17)
a
–
128 (128)
a
–
13 (17)
a
–
128 (128)
a
–
a
a
a
–
a
–
a
a
–
7j
–
–
–
a
a
a
a
a
a
7k
7l
–
–
–
–
–
–
14 (14)
14 (16)
14 (15)
15 (17)
128 ([128)
128 (128)
128 (128)
128 (128)
16
14 (14)
14 (16)
14 (15)
15 (15)
24
128 ([128)
128 (128)
128 (128)
128 (128)
16
13 (14)
12 (16)
13 (15)
14 (14)
23
128 (128)
128 (128)
128 (128)
128 ([128)
16
7m
7n
7o
Chloramphenicol 22
The values in brackets are for the HCl salt of the compound
The zone of inhibition and MIC values for compound with significant activity are shown in bold
a
No activity was observed
but it did not show any activity towards F. monalliforme.
On the other hand, 7a showed most significant activity
towards all of the three fungi both in salted form and in
neutral form. It is worth to note that most of the compounds
were inactive towards F. monalliforme fungi in both forms.
Compound 7d, 7j, and 7o did not show any antifungal
activity in salt form, but in neutral form they showed
moderate activity towards F. oxysporum and F. gramil-
larium. Most of the other compounds were moderately
active towards F. oxysporum and F. Gramillarium.
123

Med Chem Res
Table 3 Antifungal activity of 7a–o and their HCl salts
Compound
F. oxysporum
F. gramillarium
F. monalliforme
Zone of inhibition
(mm)
MIC
(lg/ml)
Zone of inhibition
(mm)
MIC
(lg/ml)
Zone of inhibition
(mm)
MIC
(lg/ml)
7a
15 (15)
14 (14)
16 (16)
12 (–a)
13 (12)
13 (13)
12 (15)
15 (15)
12 (12)
14 (15)
15 (–a)
14 (15)
14 (12)
11 (12)
15 (–a)
20
>64 (128)
128 (128)
128 (>64)
[128 (–a)
[128 ([128)
[128 ([128)
[128 (128)
128 (128)
[128 ([128)
128 (128)
128 (–a)
15 (15)
14 (14)
16 (16)
14 (–a)
13 (12)
13 (13)
12 (15)
15 (–a)
12 (12)
14 (15)
15 (–a)
14 (15)
14 (12)
11 (–a)
15 (–a)
19
>64 (128)
128 (128)
128 (>64)
[128 (–)
[128 ([128)
[128 ([128)
[128 (128)
128 (–)
–a (12)
14 (–)
–a ([128)
128 (–a)
7b
7c
14 (14)
a
–
128 ([128)
a
7d
–
a
a
7e
–
–
7f
11 (–a)
–a (14)
12 (–a)
[128 (–a)
–a ([128)
[128 (–a)
7g
7h
a
a
7i
[128 ([128)
128 (128)
128 (–)
–
–
7j
–a (12)
–a ([128)
a
a
7k
–
–
a
a
7l
128 (128)
128 ([128)
128 ([128)
128 (–a)
128 (128)
128 ([128)
128 (–a)
–
–
7m
–a (12)
–a (128)
a
a
7n
–
–
a
a
7o
128 (–a)
–
–
Carbendazim
16
16
19
16
The values in brackets are for the HCl salt of the compound
The zone of inhibition and MIC values for compound with significant activity are shown in bold
a
No activity was observed
Reactions were monitored by using thin layer chromatog-
raphy (TLC) on 0.2-mm silica gel F254 plates (Merck).
The chemical structures of final products were character-
Conclusions
In conclusion, an array of novel piperazine-1,2,3-triazoles
derivatives has been synthesized by employing click
chemistry which involved the bioisosteric modification of
the imidazole scaffold and hybridization of two drug
scaffolds. The yield of the compounds was good to ex-
cellent, and all the synthesized compounds were of high
purity. The compounds were evaluated for antibacterial
activities against Gram-negative (E. coli and P. putida),
and Gram-positive S. aureus bacteria as well as for
fungicidal activities against F. oxysporum, F. gramil-
larium, and F. monalliforme fungi. Compound 7c exhibited
moderate but promising antibacterial activity against
Gram-negative bacteria and fungicidal activity against F.
oxysporum and F. gramillarium.
ized by nuclear magnetic resonance spectra (1H NMR, 13
C
NMR) determined at room temperature with a Bruker
Avance DMX-500 spectrometer at 300 and 75 MHz, re-
spectively. Chemical shifts were reported in parts per
million (ppm) using deuterated solvent peak or tetram-
ethylsilane (internal) as the standard.
Preparation of 1-((1-(2-(benzyloxy)-2-phenylethyl)-1H-
1,2,3-triazol-4-yl)methyl)-4-phenyl piperazine (7a)
Mixture of (2-azido-1-(benzyloxy)ethyl)benzene (1.0 m-
mol), 1-phenyl-4-(prop-2-ynyl)piperazine (1.2 mmol) and
CuI (0.05 mmol) in water: PEG 400 (1:1 v/v) (10 mL) was
stirred at room temperature for 5 h. After completion, water
was added and extracted into ethyl acetate. Organic layerwas
then separated and dried over sodium sulphate, and then the
volatiles were evaporated. The crude residue was purified by
column chromatography (EtOAc: hexane, 1:3).
Experimental
Chemistry
General procedure for HCl salt formation of 7
All chemicals were obtained from commercial suppliers
and used without further purification. Melting points were
determined in open capillary tubes on an EZ-Melt auto-
mated melting point apparatus and are uncorrected.
Free bases were dissolved in CH2Cl2 and treated with
dry HCl gas, which were generated in situ. After 15 min,
123

Med Chem Res
the solids were filtered and dried under vacuum to afford
C-5), 128.98 (C-30, C-50), 128.97 (C-40), 128.6 (C-300,
C-500), 126.9 (C-20, C-60), 124.2 (C-5, triazole), 119.7 (C-
4), 116.1 (C-2, C-6), 80.1 (O–CH), 70.1 (CH2-benzyl), 56.0
(CH2-triazole), 53.3 (CH2-piperazine), 52.8 (C-2,C-6,
piperazine), 49.1 (C-3,C-5, piperazine); HRMS (ESI) m/z:
Calcd for C28H31ClN5O 488.2212, found 488.2198
[M ? H]?.
quantitative yields of corresponding HCl salts of 7a–o.
1-((1-(2-(2-Chloro-4-fluorobenzyloxy)-2-phenylethyl)-1H-
1,2,3-triazol-4-yl)methyl)-4-phenylpiperazine (7c)
Colourless solid; yield: 96 %; mp 86–87 °C; 1H NMR
(300 MHz, CDCl3) d 7.50 (s, 1H, triazole), 7.45–7.34 (m,
5H, Ar–H), 7.30–7.18 (m, 3H, Ar–H), 7.07 (dd, J = 8.5,
2.6 Hz, 1H, Ar–H), 6.98–6.89 (m, 3H, Ar–H), 6.85 (t,
J = 7.3 Hz, 1H, Ar–H), 4.82 (dd, J = 8.4, 4.3 Hz, 1H,
OCH), 4.59–4.52 (m, 2H, CH2N-triazole), 4.47 (d,
J = 12.1 Hz, 1H, OCH2), 4.31 (d, J = 12.1 Hz, 1H,
OCH2), 3.73 (s, 2H, CH2N-piperazine), 3.20–3.14 (m, 4H,
CH2-piperazine C3 & C5), 2.67–2.56 (m, 4H, CH2-piper-
azine C2 & C6); 13C NMR (75 MHz, CDCl3) d 162.1 (d,
J = 250.0 Hz, C-400), 151.3 (C-1), 143.8 (C-10), 137.5 (C-
4, triazole), 134.1 (d, J = 10.4 Hz, C-200), 131.1 (d,
J = 3.6 Hz, C-100), 130.7 (d, J = 8.8 Hz, C-600), 129.1 (C-
20, C-60) 129.0 (C-30, C-50), 126.7 (C-40), 124.2 (C-2, C-6),
119.7 (C-5, triazole), 116.9 (d, J = 24.7 Hz, C-300), 116.1
(C-2, C-6), 114.0 (d, J = 21.0 Hz, C-500), 80.6 (O–CH),
67.7 (CH2-benzyl), 56.0 (CH2-triazole), 53.3(CH2-piper-
azine), 52.8 (C-2,C-6, piperazine), 49.0 (C-3,C-5, piper-
azine); HRMS (ESI) m/z: Calcd for C28H30ClFN5O
506.2117, found 506.2126 [M ? H]?.
1-((1-(2-(Benzyloxy)-2-phenylethyl)-1H-1,2,3-triazol-4-
yl)methyl)-4-phenylpiperazine (7a)
Colourless solid; yield: 89 %; mp 82–83 °C; 1H NMR
(300 MHz, CDCl3) d 7.51 (s, 1H, triazole), 7.45–7.33 (m,
5H, Ar–H), 7.32–7.22 (m, 5H, Ar–H), 7.17–7.10 (m, 2H,
Ar–H), 6.96–6.89 (m, 2H, Ar–H), 6.85 (t, J = 7.3 Hz, 1H,
Ar–H), 4.79 (dd, J = 8.4, 4.3 Hz, 1H, OCH), 4.58–4.46
(m, 3H, OCH2 & CH2N-triazole), 4.21 (d, J = 11.6 Hz,
1H, OCH), 3.74 (s, 2H, CH2N-piperazine), 3.18 (t,
J = 4.8 Hz, 4H, CH2-piperazine C3 & C5), 2.64 (t,
J = 4.8 Hz, 4H, CH2-piperazine C2 & C6); 13C NMR
(75 MHz, CDCl3) d 151.3 (C-1), 143.8 (C-100), 137.8 (C-
10), 137.4 (C-4, triazole), 129.1 (C-3,C-5), 129.0 (C-300,C-
500), 128.8 (C-30,C-50), 128.5 (C-400), 127.9 (C-40), 127.7
(C-200, C-600), 126.8 (C-20,C-60), 124.3 (C-5, triazole), 119.7
(C-4), 116.1 (C-2, C-6), 80.0 (OCH), 70.9 (OCH2), 56.1
(CH2N-triazole), 53.3 (CH2N-piperazine), 52.8 (C-2, C-6
piperazine), 49.0 (C-3,C-5, piperazine); HRMS (ESI) m/z:
Calcd for C28H32N5O 454.2601, found 454.2623
[M ? H]?.
1-((1-(2-(4-Bromo-2-fluorobenzyloxy)-2-phenylethyl)-1H-
1,2,3-triazol-4-yl)-methyl)-4-phenylpiperazine (7d)
Colourless solid; yield: 89 %; mp 86–87 °C; 1H NMR
(300 MHz, CDCl3) d 7.48 (s, 1H, triazole), 7.45–7.32 (m,
5H, Ar–H), 7.30–7.14 (m, 4H, Ar–H), 7.05 (t, J = 7.9 Hz,
1H, Ar–H), 6.92 (d, J = 8.1 Hz, 2H, Ar–H), 6.85 (t,
J = 7.2 Hz, 1H, Ar–H), 4.79 (dd, J = 8.5, 4.0 Hz, 1H,
OCH), 4.62–4.48 (m, 2H, CH2N-triazole), 4.45 (d,
J = 12.0 Hz, 1H, OCH2), 4.26 (d, J = 12.0 Hz, 1H,
OCH2), 3.74 (s, 2H, CH2N-piperazine), 3.25–3.09 (m, 4H,
CH2-piperazine C3 & C5), 2.70–2.61 (m, 4H, CH2-piper-
azine C2 & C6); 13C NMR (75 MHz, CDCl3) d 160.5 (d,
J = 252.5 Hz, C-200), 151.3 (C-1), 143.8 (C-10), 137.4 (C-
4, triazole), 131.1 (d, J = 4.9 Hz, C-600), 129.11 (C-3,
C-5), 129.1 (C-30, C-50), 129.0 (C-40), 127.5 (d,
J = 3.8 Hz, C-500), 126.7(C-20), 124.1 (C-60), 123.7 (d,
J = 14.9 Hz, C-400), 122.1 (d, J = 9.6 Hz, C-100), 119.7
(C-5, triazoles), 119.1 (d, J = 24.7 Hz, C-300), 116.1 (C-4),
80.5 (O–CH), 64.2 (d, J = 3.3 Hz, CH2-benzyl), 56.0
(CH2-triazole), 53.3 (CH2-piperazine), 52.8 (C-2,C-6,
1-((1-(2-(4-Chlorobenzyloxy)-2-phenylethyl)-1H-1,2,3-
triazol-4-yl)methyl)-4-phenylpiperazine (7b)
Yellow solid; yield: 88 %; mp 83–84 °C; 1H NMR
(300 MHz, CDCl3) d 7.47 (s, 1H, triazole), 7.45–7.32 (m,
5H, Ar–H), 7.31–7.27 (m, 2H, Ar–H), 7.26–7.21 (m, 2H,
Ar–H), 7.05 (d, J = 8.4 Hz, 2H, Ar–H), 6.92 (d,
J = 8.0 Hz, 2H, Ar–H), 6.85 (t, J = 7.3 Hz, 1H, Ar–H),
4.78 (dd, J = 8.2, 4.5 Hz, 1H, OCH), 4.58–4.51 (m, 2H,
CH2N-triazole), 4.44 (d, J = 11.8 Hz, 1H, OCH2), 4.18 (d,
J = 11.8 Hz, 1H, OCH2), 3.74 (s, 2H, CH2N-piperazine),
3.20–3.14 (m, 4H, CH2-piperazine C3 & C5), 2.66–2.60 (m,
4H, CH2-piperazine C2 & C6); 13C NMR (75 MHz, CDCl3)
d 151.3 (C-1), 143.8 (C-10), 137.6 (C-100), 135.9 (C-400),
133.7 (C-4, triazole), 129.12(C-200, C-600), 129.07 (C-3,
123

Med Chem Res
piperazine), 49.0 (C-3,C-5, piperazine); HRMS (ESI) m/z:
Calcd for C28H30BrFN5O 550.1612, found 550.1635
[M ? H]?.
3H, Ar–H), 6.87–6.81 (m, 2H, Ar–H), 5.07 (dd, J = 7.9,
4.1 Hz, 1H, OCH), 4.66–4.56 (m, 2H, CH2N-triazole), 4.44
(d, J = 11.8 Hz, 1H, OCH2), 4.22 (d, J = 11.8 Hz, 1H,
OCH2), 3.74 (s, 2H, CH2N-piperazine), 3.23–3.14 (m, 4H,
CH2-piperazine C3 & C5), 2.67–2.60 (m, 4H, CH2-piper-
azine C2 & C6); 13C NMR (75 MHz, CDCl3) d 151.2 (C-
200), 144.0 (C-400), 135.4 (C-1), 133.9 (C-10), 129.1 (C-40),
129.0 (C-4, triazole), 128.7 (C-600), 124.0 (C-200, C-600),
120.6 (C-3, C-5), 119.7 (C-30, C-50), 116.1 (C-5, triazole)
112.3 (C-4), 112.0 (C-100), 104.8 (C-2, C-6), 104.4 (C-500),
104.1 (C-300), 73.7 (O–CH), 70.6 (CH2-benzyl), 54.5 (CH2-
triazole), 53.2 (CH2-piperazine), 52.8 (C-2,C-6, piper-
azine), 49.0 (C-3,C-5, piperazine); HRMS (ESI) m/z: Calcd
for C28H29ClF2N5O 524.2023, found 524.2035 [M ? H]?.
1-((1-(2-(Benzyloxy)-2-(4-fluorophenyl)ethyl)-1H-1,2,3-
triazol-4-yl)methyl)-4-phenylpiperazine (7e)
Brown solid; yield: 78 %; mp 114–115 °C; 1H NMR
(300 MHz, CDCl3) d 7.70 (s, 1H, triazole), 7.37–7.25 (m,
7H, Ar–H), 7.16–7.05 (m, 4H, Ar–H), 6.94–6.84 (m, 3H,
Ar–H), 4.79 (dd, J = 7.1, 5.5 Hz, 1H, OCH), 4.58–4.52
(m, 2H, CH2N-triazole), 4.47 (d, J = 11.7 Hz, 1H, OCH2),
4.21 (d, J = 11.7 Hz, 1H, OCH2), 3.91 (s, 2H, CH2N-
piperazine), 3.30–3.22 (m, 4H, CH2-piperazine C3 & C5),
2.86–2.73 (m, 4H, CH2-piperazine C2 & C6); 13C NMR
(75 MHz, CDCl3) d 162.9 (d, J = 247.7 Hz, C-400), 150.8
(C-1), 141.5 (C-10), 137.1 (C-4, triazole), 133.4 (d,
J = 3.2 Hz, C-100), 129.2 (C-3, C-5), 128.6 (C-30, C-50),
128.5 (C-40), 128.0 (C-20, C-60), 127.7 (C-200, C-600), 125.4
(C-5, triazole), 120.3 (C-2, C-6), 116.4 (C-4), 116.0 (d,
J = 21.6 Hz, C-300, C-500), 79.0 (O–CH), 70.8 (CH2-ben-
zyl), 56.1 (CH2-triazole), 52.3 (CH2-piperazine), 52.1 (C-
2,C-6, piperazine), 48.3 (C-3,C-5, piperazine); HRMS
(ESI) m/z: Calcd for C28H31FN5O 472.2507, found
472.2511 [M ? H]?.
1-((1-(2-(2-Chloro-4-fluorobenzyloxy)-2-(2,4-
difluorophenyl)-ethyl)-1H-1,2,3-triazol-4-yl)methyl)-4-
phenylpiperazine (7h)
1
Colourless solid; yield: 81 %; mp 99–100 °C; H NMR
(300 MHz, CDCl3) d 7.56 (s, 1H, triazole), 7.41–7.22 (m,
4H, Ar–H), 7.08 (dd, J = 8.4, 2.5 Hz, 1H, Ar–H),
6.99–6.81 (m, 6H, Ar–H), 5.12 (dd, J = 7.9, 3.9 Hz, 1H,
OCH), 4.67–4.57 (m, 2H, CH2N-triazole), 4.49 (d,
J = 12.0 Hz, 1H, OCH2), 4.35 (d, J = 12.0 Hz, 1H,
OCH2), 3.74 (s, 2H, CH2N-piperazine), 3.23–3.13 (m, 4H,
CH2-piperazine C3 & C5), 2.70–2.58 (m, 4H, CH2-piper-
azine C2 & C6); 13C NMR (75 MHz, CDCl3) d 162.2 (d,
J = 250.3 Hz, C-40), 151.2 (C-2000), 144.0 (C-1), 134.2 (d,
J = 10.3 Hz, C-400), 133.2 (C-1 ), 130.8 (d, J = 8.8 Hz,
C-20), 130.6 (d, J = 3.4 Hz, C-600), 129.1 (C-4, triazole),
124.0 (C-60), 119.7 (C-3, C-5), 117.0 (d, J = 24.8 Hz,
C-300), 114.1 (d, J = 21.1 Hz, C-500), 112.2 (d, J = 3.6 Hz,
C-100), 112.0 (d, J = 3.6 Hz, C-30), 104.8 (C-5, triazole),
104.4 (C-4), 104.4 (C-2, C-6), 104.1 (C-50), 74.2 (O–CH),
68.2 (CH2-benzyl), 54.5 (CH2-triazole), 53.2 (CH2-piper-
azine), 52.8 (C-2,C-6, piperazine), 49.0 (C-3,C-5, piper-
azine); HRMS (ESI) m/z: Calcd for C28H28ClF3N5O
542.1929, found 542.1906 [M ? H]?.
1-((1-(2-(4-Chlorobenzyloxy)-2-(4-fluorophenyl)ethyl)-1H-
1,2,3-triazol-4-yl)-methyl)-4-phenylpiperazine (7f)
Yellow solid; yield: 73 %; mp 112–113 °C; 1H NMR
(300 MHz, CDCl3) d 8.01 (s, 1H, triazole), 7.39–7.19 (m,
6H, Ar–H), 7.16–6.99 (m, 4H, Ar–H), 6.90 (d, J = 7.1 Hz,
3H, Ar–H), 4.83 (dd, J = 14.7, 9.3 Hz, 1H, OCH), 4.55 (s,
2H, CH2N-piperazine), 4.40 (d, J = 11.8 Hz, 1H, OCH2),
4.23–4.09 (m, 3H, OCH2 and CH2N-triazole), 3.45–3.27
(m, 4H, CH2-piperazine C3 & C5), 3.10–2.93 (m, 4H, CH2-
piperazine C2 & C6); 13C NMR (75 MHz, CDCl3) d 163.0
(d, J = 247.8 Hz, C-400), 150.3 (C-1), 139.6 (C-10), 135.7
(C-100), 133.6 (C-4, triazole), 133.1 (d, J = 3.1 Hz, C-40),
129.3 (C-20, C-60), 129.0 (C-3, C-5), 128.7 (C-30, C-50),
128.6 (C-200, C-600), 126.6 (C-5, triazole), 120.7 (C-4),
116.6 (C-2, C-6), 116.1 (d, J = 21.7 Hz, C-300, C-500), 79.0
(O–CH), 70.0 (CH2-benzyl), 56.1 (CH2-triazole), 52.2
(CH2-piperazine), 52.0 (C-2,C-6, piperazine), 47.8 (C-3,C-
5, piperazine); HRMS (ESI) m/z: Calcd for C28H30ClFN5O
506.2117, found 506.2134 [M ? H]?.
1-((1-(2-(4-Chlorobenzyloxy)-2-(4-chlorophenyl)ethyl)-
1H-1,2,3-triazol-4-yl)methyl)-4-phenylpiperazine (7i)
Brown solid; yield: 72 %; mp 128–129 °C; 1H NMR
(300 MHz, CDCl3) d 7.39 (s, 1H, triazole), 7.33–7.28 (m,
2H, Ar–H), 7.23–7.14 (m, 6H, Ar–H), 6.97 (d, J = 8.4 Hz,
2H, Ar–H), 6.85 (d, J = 7.9 Hz, 2H, Ar–H), 6.78 (t,
J = 7.3 Hz, 1H, Ar–H), 4.70 (dd, J = 7.3, 5.4 Hz, 1H,
OCH), 4.47–4.43 (m, 2H, CH2N-triazole), 4.35 (d,
J = 11.8 Hz, 1H, OCH2), 4.10 (d, J = 11.8 Hz, 1H,
OCH2), 3.67 (s, 2H, CH2N-piperazine), 3.15–3.08 (m, 4H,
CH2-piperazine C3 & C5), 2.62–2.51 (m, 4H, CH2-piper-
azine C2 & C6); 13C NMR (75 MHz, CDCl3) d 151.2 (C-1),
1-((1-(2-(4-Chlorobenzyloxy)-2-(2,4-difluorophenyl)ethyl)-
1H-1,2,3-triazol-4-yl)methyl)-4-phenylpiperazine (7g)
Yellow solid; yield: 80 %; mp 91–92 °C;1H NMR
(300 MHz, CDCl3) d 7.52 (s, 1H, triazole), 7.39–7.24 (m,
5H, Ar–H), 7.07 (d, J = 8.4 Hz, 2H, Ar–H), 6.96–6.88 (m,
123

Med Chem Res
143.9 (C-100), 136.1 (C-10), 135.6 (C-40), 134.8 (C-400),
133.8 (C-4, triazoles), 129.3 (C-20, C-60), 129.1 (C-3, C-5),
129.0 (C-30, C-50), 128.7 (C-300, C-500), 128.1 C-200, C-600),
124.3 (C-5, triazole), 119.7 (C-4), 116.1 (C-2, C-6), 79.4
(O–CH), 70.2 (CH2-benzyl), 55.8 (CH2-triazole), 53.2
(CH2-piperazine), 52.8 (C-2,C-6, piperazine), 49.0 (C-3,C-
5, piperazine); HRMS (ESI) m/z: Calcd for C28H30Cl2N5O
522.1822, found 522.1813 [M ? H]?.
4), 119.1 (d, J = 24.6 Hz, C-30), 116.1 (C-2, C-6), 79.8
(O–CH), 64.4 (CH2-benzyl), 55.8 (CH2-triazole), 53.2
(CH2-piperazine), 52.8 (C-2,C-6, piperazine), 49.0 (C-3,C-
5, piperazine); HRMS (ESI) m/z: Calcd for C28H29
BrClFN5O 584.1223, found 584.1221 [M ? H]? and
586.1234 [M ? H ? 2]?.
1-((1-(2-(4-Chlorobenzyloxy)-2-(2,4-
dichlorophenyl)ethyl)-1H-1,2,3-triazol-4-yl)methyl)-4-
phenylpiperazine (7l)
1-((1-(2-(2-Chloro-4-fluorobenzyloxy)-2-(4-chlorophenyl)-
ethyl)-1H-1,2,3-triazol-4-yl)methyl)-4-phenylpiperazine
(7j)
Colourless solid; yield: 63 %; mp 88–89 °C; 1H NMR
(300 MHz, CDCl3) d 7.43 (s, 1H, triazole), 7.36 (d,
J = 2.0 Hz, 1H, Ar–H), 7.34–7.18 (m, 5H, Ar–H), 7.16 (s,
1H, Ar–H), 7.00 (d, J = 8.4 Hz, 2H, Ar–H), 6.85 (d,
J = 7.9 Hz, 2H, Ar–H), 6.77 (t, J = 7.3 Hz, 1H, Ar–H),
5.11 (dd, J = 8.1, 3.3 Hz, 1H, OCH), 4.57 (d,
J = 11.8 Hz, 1H, OCH2), 4.44–4.34 (m, 2H, CH2N-tria-
zole), 4.12 (d, J = 11.8 Hz, 1H, OCH2), 3.67 (s, 2H,
CH2N-piperazine), 3.16–3.07 (m, 4H, CH2-piperazine C3
& C5), 2.61–2.54 (m, 4H, CH2-piperazine C2 & C6); 13C
NMR (75 MHz, CDCl3) d 151.2 (C-1), 144.2 (C-10), 135.3
(C-400), 135.2 (C-200), 133.9 (C-40), 133.8 (C-100), 133.7 (C-
4, triazole), 129.8 (C-300, C-600), 129.1 (C-20, C-60), 128.7
(C-3, C-5), 128.6 (C-30, C-50), 128.0 (C-500) 123.8 (C-5,
triazole), 119.7 (C-4), 116.1 (C-2, C-6), 76.2 (O–CH), 70.7
(CH2-benzyl), 54.1 (CH2-triazole), 53.3 (CH2-piperazine),
52.9 (C-2,C-6, piperazine), 49.0 (C-3,C-5, piperazine);
HRMS (ESI) m/z: Calcd for C28H29Cl3N5O 556.1432,
found 556.1423 [M ? H]?.
1
Off-white solid; yield: 99 %; mp 112–113 °C; H NMR
(300 MHz, CDCl3) d 7.48 (s, 1H, triazole), 7.41–7.36 (m,
2H, Ar–H), 7.32–7.26 (m, 3H, Ar–H), 7.25–7.17 (m, 2H,
Ar–H), 7.08 (dd, J = 8.4, 2.6 Hz, 1H, Ar–H), 6.98–6.89
(m, 3H, Ar–H), 6.85(t, J = 7.3 Hz, 1H, Ar–H), 4.82 (dd,
J = 7.6, 5.0 Hz, 1H, OCH), 4.58–4.51 (m, 2H, CH2N-
triazole), 4.46 (d, J = 12.0 Hz, 1H, OCH2), 4.31 (d,
J = 12.0 Hz, 1H, OCH2), 3.73 (s, 2H, CH2N-piperazine),
3.22–3.14 (m, 4H, CH2-piperazine C3 & C5), 2.66–2.59 (m,
4H, CH2-piperazine C2 & C6); 13C NMR (75 MHz, CDCl3)
d 162.1 (d, J = 250.4 Hz, C-40), 151.2 (C-1), 143.9 (C-100),
136.1 (C-20), 134.9 (C-400), 134.2 (d, J = 10.4 Hz, C-60),
130.8 (C-10), 130.8 (C-4, triazole), 130.7 (C-3,C-5), 129.2
(C-300, C-500), 128.1 (C-200, C-600), 124.2 (C-5, triazole),
119.7 (C-4), 117.0 (d, J = 24.8 Hz, C-30), 116.1 (C-2,
C-6), 114.1 (d, J = 21.0 Hz, C-50), 79.9 (O–CH), 67.8
(CH2-benzyl), 55.8 (CH2-triazole), 53.2 (CH2-piperazine),
52.8 (C-2,C-6, piperazine), 49.0 (C-3,C-5, piperazine);
HRMS (ESI) m/z: Calcd for C28H29Cl2FN5O 540.1728,
found 540.1699 [M ? H]?.
1-((1-(2-(2-Chloro-4-fluorobenzyloxy)-2-(2,4-
dichlorophenyl)-ethyl)-1H-1,2,3-triazol-4-yl)methyl)-4-
phenylpiperazine (7m)
1-((1-(2-(4-Bromo-2-fluorobenzyloxy)-2-(4-chlorophenyl)-
ethyl)-1H-1,2,3-triazol-4-yl)methyl)-4-phenylpiperazine
(7k)
1
Colourless solid; yield: 81 %; mp 104–105 °C; H NMR
(300 MHz, CDCl3) d 7.54 (s, 1H, triazole), 7.45 (d,
J = 1.9 Hz, 1H, Ar–H), 7.41 (d, J = 8.4 Hz, 1H, Ar–H),
7.34–7.21 (m, 4H, Ar–H), 7.08 (dd, J = 8.4, 2.5 Hz, 1H,
Ar–H), 6.99–6.90 (m, 3H, Ar–H), 6.85 (t, J = 7.3 Hz, 1H,
Ar–H), 5.23 (dd, J = 8.1, 3.1 Hz, 1H, OCH), 4.67 (d,
J = 12.0 Hz, 1H, OCH2), 4.57–4.42 (m, 2H, CH2N-tria-
zole), 4.33 (d, J = 12.0 Hz, 1H, OCH2), 3.74 (s, 2H,
CH2N-piperazine), 3.26–3.14 (m, 4H, CH2-piperazine C3
& C5), 2.73–2.59 (m, 4H, CH2-piperazine C2 & C6); 13C
NMR (75 MHz, CDCl3) d 162.2 (d, J = 250.6 Hz, C-40),
151.2 (C-1), 144.1 (C-400), 135.2 (C-200), 134.3 (d,
J = 10.4 Hz, C-20), 133.7 (C-100), 133.6 (C-4, triazole),
130.9 (d, J = 8.9 Hz, C-60), 130.5 (d, J = 3.6 Hz, C-10),
129.8 (C-300), 129.1 (C-600), 128.2 (d, J = 42.2 Hz, C-30),
123.9 (C-3, C-5), 119.7 (C-500), 117.0 (d, J = 24.8 Hz,
C-50), 116.1 (C-5, triazole), 114.3 (C-4), 114.0 (C-2, C-6),
76.7 (O–CH), 68.3 (CH2-benzyl), 54.1 (CH2-triazole), 53.3
Brown solid; yield: 98 %; mp 92-94 °C; 1H NMR
(300 MHz, CDCl3) d 7.48 (s, 1H, triazole), 7.39 (d,
J = 8.4 Hz, 2H, Ar–H), 7.31–7.17 (m, 6H, Ar–H), 7.04 (t,
J = 7.9 Hz, 1H, Ar–H), 6.93 (d, J = 8.0 Hz, 2H, Ar–H),
6.85 (t, J = 7.3 Hz, 1H, Ar–H), 4.78 (dd, J = 8.0, 4.5 Hz,
1H, OCH), 4.58–4.48 (m, 2H, CH2N-triazole), 4.43 (d,
J = 11.8 Hz, 1H, OCH2), 4.25 (d, J = 11.9 Hz, 1H,
OCH2), 3.74 (s, 2H, CH2N-piperazine), 3.25–3.16 (m, 4H,
CH2-piperazine C3 & C5), 2.70–2.60 (m, 4H, CH2-piper-
azine C2 & C6); 13C NMR (75 MHz, CDCl3) d 160.5 (d,
J = 252.6 Hz, C-20), 151.2 (C-1), 143.8 (C-100), 135.9 (C-
400), 134.9 (C-4, triazole), 131.2 (d, J = 4.8 Hz, C-40),
129.3 (C-3, C-5), 129.1 (C-300, C-500), 128.1(C-200, C-600),
127.6 (d, J = 3.7 Hz, C-60), 124.2 (C-5, triazole), 123.4 (d,
J = 14.9 Hz, C-50), 122.4 (d, J = 9.5 Hz, C-10), 119.7 (C-
123

Med Chem Res
Antibacterial assay
(CH2-piperazine), 52.9 (C-2,C-6, piperazine), 49.0 (C-3,C-
5, piperazine); HRMS (ESI) m/z: Calcd for C28H28Cl3
FN5O 574.1338, found 574.1351 [M ? H]?.
Antibacterial assay of the compounds was performed using
well diffusion method. Mueller–Hinton (Himedia, India)
agar medium was prepared for experimental work and
sterilized by autoclaving at 121 °C at 15 psi for 15 min.
The medium was poured into sterile Petri dishes, under
aseptic conditions using laminar air flow chamber. After
the solidification of medium, the suspension of the test
organism (106 cfu/mL) was spread onto the individual
media plates using a sterile glass spreader. After some
time, wells of 9 mm diameter were made by the sterile
metallic borer and the solution of working compound of
concentration 128 lg/mL was poured into the wells. The
experiment was performed in triplicates of each compound.
Zone of inhibition assay was performed at 128 lg/mL
concentration for all the compounds using well diffusion
method. The plates were incubated at 37 °C for 18–24 h
under dark conditions. The determination as to whether the
organism is susceptible, intermediate, or resistant was
made by measuring the size of zone of inhibition in com-
parison with standard antibiotic. MIC assay was performed
to determine the lowest concentrations of compound nec-
essary to inhibit a test organism. MIC values were
evaluated for all the compounds using broth micro dilution
method. Assay was carried out for the compounds at 0.5,
1.0, 2.0, 4.0, 8.0, 16.0, 32.0, 64.0, 128.0 lg/mL concen-
trations. A set of tubes containing Mueller–Hinton broth
medium with different concentrations of compound was
prepared. The tubes were inoculated with bacterial cultures
(106 cfu/mL) and incubated on a rotary shaker (180 rpm) at
37 °C for 18–24 h under dark conditions. MIC values were
defined as lowest concentrations of compound that pre-
vented the visible growth of the bacteria after the incuba-
tion period. All the experiments were performed in
triplicates. Chloramphenicol was used as a positive control
at a concentration 16 lg/mL.
1-((1-(2-(4-Bromo-2-fluorobenzyloxy)-2-(2,4-
dichlorophenyl)-ethyl)-1H-1,2,3-triazol-4-yl)methyl)-4-
phenylpiperazine (7n)
Yellow solid; yield: 68 %; mp 91-92 °C; 1H NMR
(300 MHz, CDCl3) d 7.53 (s, 1H, triazole), 7.46–7.35 (m,
2H, Ar–H), 7.35–7.14 (m, 5H, Ar–H), 7.07 (t, J = 7.7 Hz,
1H, Ar–H), 6.92 (d, J = 7.7 Hz, 2H, Ar–H), 6.84 (t,
J = 7.0 Hz, 1H, Ar–H), 5.19 (d, J = 5.5 Hz, 1H, OCH),
4.65 (d, J = 11.7 Hz, 1H, OCH2), 4.54–4.37 (m, 2H,
CH2N-triazole), 4.26 (d, J = 11.7 Hz, 1H, OCH2), 3.75 (s,
2H, CH2N-piperazine), 3.33–3.14 (m, 4H, CH2-piperazine
C3 & C5), 2.81–2.53 (m, 4H, CH2-piperazine C2 & C6); 13
C
NMR (75 MHz, CDCl3) d 160.5 (d, J = 252.5 Hz, C-20),
151.2 (C-1), 144.1 (C-400), 135.3 (C-200), 133.8 (C-100),
133.5 (C-4, triazole), 131.3 (d, J = 4.7 Hz, C-60), 129.8
(C-300), 129.1 (C-600), 128.5 (C-3, C-5), 128.0 (C-500), 127.6
(d, J = 3.7 Hz, C-50), 123.8 (C-5, triazole), 123.1 (d,
J = 15.0 Hz, C-40), 122.5 (d, J = 9.5 Hz, C-10), 119.7 (C-
4), 119.1 (d, J = 24.6 Hz, C-30), 116.1 (C-2, C-6), 65.0
(O–CH), 64.9 (CH2-benzyl), 54.1 (CH2-triazole), 53.3
(CH2-piperazine), 52.9 (C-2,C-6, piperazine), 49.0 (C-3,C-
5, piperazine); HRMS (ESI) m/z: Calcd for C28H28BrCl2
FN5O 618.0833, found 618.0818 [M ? H]? and 620.0809
[M ? H ? 2]?.
1-((1-(2-(4-Bromophenyl)-2-(4-chlorobenzyloxy)ethyl)-1H-
1,2,3-triazol-4-yl)methyl)-4-phenylpiperazine (7o)
Yellow solid; yield: 67 %; mp 85–86 °C; 1H NMR
(300 MHz, CDCl3) d 7.54 (d, J = 8.4 Hz, 2H, Ar–H), 7.46
(s, 1H, triazole), 7.29–7.18 (m, 6H, Ar–H), 7.05 (d,
J = 8.4 Hz, 2H, Ar–H), 6.92 (d, J = 8.0 Hz, 2H, Ar–H),
6.85 (t, J = 7.3 Hz, 1H, Ar–H), 4.76 (dd, J = 7.3, 5.4 Hz,
1H, OCH), 4.55–4.50 (m, 2H, CH2N-triazole), 4.42 (d,
J = 11.8 Hz, 1H, OCH2), 4.17 (d, J = 11.8 Hz, 1H,
OCH2), 3.75 (s, 2H, CH2N-piperazine), 3.24–3.14 (m, 4H,
CH2-piperazine C3 & C5), 2.74–2.60 (m, 4H, CH2-piper-
azine C2 & C6); 13C NMR (75 MHz, CDCl3) d 151.2 (C-1),
143.8 (C-100), 136.6 (C-10), 135.5 (C-40), 133.8 (C-300,
C-500), 132.3 (C-4, triazole), 129.1 (C-20, C-60), 129.0 (C-3.
C-5), 128.7 (C-30, C-50), 128.4 (C-200, C-600), 124.3 (C-5,
triazole), 123.0 (C-400), 119.8 (C-4), 116.1 (C-2, C-6), 79.4
(O–CH), 70.2 (CH2-benzyl), 55.7 (CH2-triazole), 53.1
(CH2-piperazine), 52.7 (C-2,C-6, piperazine), 49.0 (C-3,C-
5, piperazine); HRMS (ESI) m/z: Calcd for C28H30
BrClN5O 566.1317, found 566.1341 [M ? H]? and
568.1332 [M ? H ? 2]?.
Antifungal assay
Antifungal activities of chemically synthesized compounds
were determined by agar well diffusion method at a con-
centration 128 lg/mL for all the compounds. For the ex-
perimental work, a microcentrifuge tube of 1.5 mL size
was filled with 1 ml autoclaved distilled water and a
loopful of freshly cultured fungus was properly mixed. A
total of 100 lL of this solution was uniformly spread on
the PDA plate. After some time, wells of 9 mm diameter
were prepared by the sterile metallic borer and 100 lL of
compound solution was added in respective wells. Plates
were incubated at 28 °C for 4 days under dark conditions.
Mean diameter of inhibition zone was measured to
123

Med Chem Res
Hou J, Liu X, Shen J, Zhao G, Wang PG (2012) The impact of click
chemistry in medicinal chemistry. Expert Opin Drug Discov
7(6):489–501
Jiang Y, Zhang J, Cao Y, Chai X, Zou Y, Wu Q, Zhang D, Jiang Y,
Sun Q (2011) Synthesis, in vitro evaluation and molecular
docking studies of new triazole derivatives as antifungal agents.
Bioorg Med Chem Lett 21(15):4471–4475
Kamal A, Shankaraiah N, Devaiah V, Laxma Reddy K, Juvekar A,
Sen S, Kurian N, Zingde S (2008) Synthesis of 1,2,3-triazole-
linked pyrrolobenzodiazepine conjugates employing ‘click’
chemistry: DNA-binding affinity and anticancer activity. Bioorg
Med Chem Lett 18(4):1468–1473
Karyotakis NC, Anaissie EJ (1994) The new antifungal azoles:
fluconazole and itraconazole. Curr Opin Infect Dis 7(6):658–666
Kolb HC, Sharpless KB (2003) The growing impact of click
chemistry on drug discovery. Drug Discov Today 8(24):1128–
1137
determine the antifungal activity. The experiment was
performed in triplicates.
MIC assay of all the compounds was performed at 0.5,
1.0, 2.0, 4.0, 8.0, 16.0, 32.0, 64.0, and 128.0 lg/mL con-
centrations. Tubes containing 10 mL of sterilized Czapek–
Dox broth medium was inoculated with 100 lL of freshly
grown culture. Appropriate amount of compound was
added to achieve the desired concentrations. The tubes
were incubated at 28 °C for 4 days under dark conditions
and carefully observed for the presence of turbidity. Car-
bendazim was used as positive control.
Acknowledgments The authors thank UGC, New Delhi [Grant No.
39-733/2010 (SR)], for financial support. PK and KP thank UGC,
New Delhi, for junior research fellowships.
Kolb HC, Finn MG, Sharpless KB (2001) Click chemistry: diverse
chemical function from a few good reactions. Angew Chem Int
Ed 40(11):2004–2021
Manohar S, Khan SI, Rawat DS (2011) Synthesis of 4-aminoquino-
line-1,2,3-triazole and 4-aminoquinoline-1,2,3-triazole-1,3,5-tri-
azine hybrids as potential antimalarial agents. Chem Biol Drug
Res 78(1):124–136
Marrapu VK, Mittal M, Shivahare R, Gupta S, Bhandari K (2011)
Synthesis and evaluation of new furanyl and thiophenyl azoles as
antileishmanial agents. Eur J Med Chem 46(5):1694–1700
Pericherla K, Khedar P, Khungar B, Kumar A (2012) Click chemistry
inspired structural modification of azole antifungal agents to
synthesize novel ‘drug like’ molecules. Tetrahedron Lett 53(50):
6761–6764
References
Agalave SG, Maujan SR, Pore VS (2011) Click chemistry: 1,2,3-
triazoles as pharmacophores. Chem Asian J 6(10):2696–2718
Alvarez R, Velazquez S, San-Felix A, Aquaro S, Clercq ED, Perno
C-F, Karlsson A, Balzarini J, Camarasa MJ (1994) 1,2,3-triazole-
[2,5-bis-o-(tert-butyldimethylsilyl)-.Beta.-d-ribofuranosyl]-30-
spiro-500-(400-amino-100,200-oxathiole 200,200-dioxide) (tsao) ana-
logs: synthesis and anti-hiv-1 activity. J Med Chem 37(24):
4185–4194
Pore VS, Jagtap MA, Agalave SG, Pandey AK, Siddiqi MI, Kumar V,
Shukla PK (2012) Synthesis and antifungal activity of 1,5-
disubstituted-1,2,3-triazole containing fluconazole analogues.
Med Chem Comm 3(4):484–488
de Oliveira Assis SP, da Silva MT, de Oliveira RN, de Menezes Lima
VL (2012) Synthesis and anti-inflammatory activity of new
alkyl-substituted phthalimide 1H-1,2,3-triazole derivatives. Sci
World J. doi:10.1100/2012/925925
Sheehan DJ, Hitchcock CA, Sibley CM (1999) Current and emerging
azole antifungal agents. Clin Microbiol Rev 12(1):40–79
Sheng C, Zhang W, Ji H, Zhang M, Song Y, Xu H, Zhu J, Miao Z,
Jiang Q, Yao J, Zhou Y, Zhu J, Lu¨ J (2006) Structure-based
optimization of azole antifungal agents by comfa, comsia, and
molecular docking. J Med Chem 49(8):2512–2525
Wahbi Y, Caujolle R, Tournaire C, Payard M, Linas MD, Seguela JP
(1995) Aromatic ethers of 1-aryl 2-(1 h-azolyl)ethanol: study of
antifungal activity. Eur J Med Chem 30(12):955–962
Wang X-L, Wan K, Zhou C-H (2010) Synthesis of novel sulfanil-
amide-derived 1,2,3-triazoles and their evaluation for antibacte-
rial and antifungal activities. Eur J Med Chem 45(10):4631–
4639
¨
Domling A, Wang W, Wang K (2012) Chemistry and biology of
multicomponent reactions. Chem Rev 112(6):3083–3135
Ferreira MLG, Pinheiro LCS, Santos-Filho OA, Pec¸anha MDS,
Sacramento CQ, Machado V, Ferreira VF, Souza TML, Boechat
N (2014) Design, synthesis, and antiviral activity of new 1 h-
1,2,3-triazole nucleoside ribavirin analogs. Med Chem Res
23(3):1501–1511
Genin MJ, Allwine DA, Anderson DJ, Barbachyn MR, Emmert DE,
Garmon SA, Graber DR, Grega KC, Hester JB, Hutchinson DK,
Morris J, Reischer RJ, Ford CW, Zurenko GE, Hamel JC,
Schaadt RD, Stapert D, Yagi BH (2000) Substituent effects
on the antibacterial activity of nitrogen—carbon-linked
(azolylphenyl)oxazolidinones with expanded activity against
the fastidious gram-negative organisms haemophilus influenzae
´
Willand N, Desroses M, Toto P, Dirie B, Lens Z, Villeret V,
Rucktooa P, Locht C, Baulard A, Deprez B (2010) Exploring
drug target flexibility using in situ click chemistry: application to
a mycobacterial transcriptional regulator. ACS Chem Biol
5(11):1007–1013
and moraxella catarrhalis. J Med Chem 43(5):953–970
¨ ¨
˘
¨
Gu¨ven OO, Erdogan T, Goker H, Yıldız S (2007) Synthesis and
antimicrobial activity of some novel phenyl and benzimidazole
substituted benzyl ethers. Bioorg Med Chem Lett 17(8):
2233–2236
Yan S-J, Liu Y-J, Chen Y-L, Liu L, Lin J (2010) An efficient one-pot
synthesis of heterocycle-fused 1,2,3-triazole derivatives as anti-
cancer agents. Bioorg Med Chem Lett 20(17):5225–5228
Holub JM, Kirshenbaum K (2010) Tricks with clicks: modification of
peptidomimetic oligomers via copper-catalyzed azide-alkyne
[3 ? 2] cycloaddition. Chem Soc Rev 39(4):1325–1337
Horne WS, Yadav MK, Stout CD, Ghadiri MR (2004) Heterocyclic
peptide backbone modifications in an a-helical coiled coil. J Am
Chem Soc 126(47):15366–15367
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