Microwave-assisted synthesis of triazole derivatives conjugated with piperidine as new anti-enzymatic agents

Article abstract of DOI:10.1002/jhet.3875

The current study was aimed for the study of piperidine-based triazole compounds for their biological potential against various enzymes. A novel library of compounds, 9a-r, having piperidine, 1,2,4-triazole, and propanamides was synthesized through consecutive steps including the formation of sulfonamide, hydrazide, 1,2,4-triazole, and thio-ether. Initially, 4-methoxybenzenesulfonyl chloride (1) and ethyl isonipecotate (2) were utilized to develop ethyl 1-(4-methoxyphenylsulfonyl)-4-piperidinecarboxylate (3). The product 3 was converted into respective hydrazide (4) which was further cyclized into 1,2,4-triazole (5) nucleus. A series of propanamides, 8a-r, were synthesized from different amines, 6a-r. These electrophiles, 8a-r, were reacted with compound 5 under conventional and microwave-assisted protocols to acquire the library of hybrids, 9a-r. The structural confirmations were availed by ¹H-NMR, ¹³C-NMR, and IR techniques. The whole series was evaluated for biological potential against acetylcholinesterase (AChE) and α-glucosidase enzymes. The biological evaluation ranges low to high in potential for different compounds based on the structural variations of synthesized compounds. Almost all the compounds remained active against both the enzymes except a few ones. The bovine serum albumin (BSA) binding study demonstrated the flow of drug in the body, and the docking study explained the interactions responsible for active behavior of synthesized compounds.

Full text of DOI:10.1002/jhet.3875

Received: 28 October 2019
DOI: 10.1002/jhet.3875
Revised: 1 December 2019
Accepted: 11 December 2019
A R T I C L E
Microwave-assisted synthesis of triazole derivatives
conjugated with piperidine as new anti-enzymatic agents
Naeem A. Virk1 | Aziz-ur- Rehman1
| Muhammad A. Abbasi1
|
Sabahat Z. Siddiqui1 | Javed Iqbal2 | Shahid Rasool1 | Shafi U. Khan3
Thet T. Htar3 | Hira Khalid4 | Sabina J. Laulloo5 | Syed A. Ali Shah6,7
|
1Department of Chemistry, Government
Abstract
College University, Lahore, Lahore,
Pakistan
The current study was aimed for the study of piperidine-based triazole com-
2Department of Chemistry, The University
of Lahore, Lahore, Pakistan
3School of Pharmacy, MONASH
University Malaysia, Subang Jaya,
Selangor, Malaysia
4Department of Chemistry, Forman
Christian College University, Lahore,
Pakistan
5Department of Chemistry, University of
Mauritius, Reduit, Mauritius
6Faculty of Pharmacy, Universiti
Teknologi MARA, Bandar Puncak Alam,
Selangor Darul Ehsan, Malaysia
7Atta-ur-Rahman Institute for Natural
Products Discovery (AuRIns), Universiti
Teknologi MARA, Bandar Puncak Alam,
Selangor Darul Ehsan, Malaysia
pounds for their biological potential against various enzymes. A novel library
of compounds, 9a-r, having piperidine, 1,2,4-triazole, and propanamides was
synthesized through consecutive steps including the formation of sulfonamide,
hydrazide, 1,2,4-triazole, and thio-ether. Initially, 4-methoxybenzenesulfonyl
chloride (1) and ethyl isonipecotate (2) were utilized to develop ethyl
1-(4-methoxyphenylsulfonyl)-4-piperidinecarboxylate (3). The product 3 was
converted into respective hydrazide (4) which was further cyclized into
1,2,4-triazole (5) nucleus. A series of propanamides, 8a-r, were synthesized
from different amines, 6a-r. These electrophiles, 8a-r, were reacted with com-
pound 5 under conventional and microwave-assisted protocols to acquire the
library of hybrids, 9a-r. The structural confirmations were availed by 1H-NMR,
13C-NMR, and IR techniques. The whole series was evaluated for biological
potential against acetylcholinesterase (AChE) and α-glucosidase enzymes. The
biological evaluation ranges low to high in potential for different compounds
based on the structural variations of synthesized compounds. Almost all the
compounds remained active against both the enzymes except a few ones. The
bovine serum albumin (BSA) binding study demonstrated the flow of drug in
the body, and the docking study explained the interactions responsible for
active behavior of synthesized compounds.
Correspondence
Aziz-ur-Rehman, Department of
Chemistry, Government College
University, Lahore, Lahore 54000,
Pakistan.
Email: rehman@gcu.edu.pk
1 | INTRODUCTION
But the microwave-assisted synthesis of triazole deriva-
tives is not so common which we have utilized in the cur-
Triazoles and their derived compounds have promising
activities in the field of agriculture, medicine, biology,
nano-chemistry, and material science.[2,10,18] Triazole-
based compounds have the ability to act as active
antiviral,[17] antifungal,[6] antibacterial, anti-inflamma-
tory, anticonvulsant, and anticancer agents.[9,11,13,14] It is
evident from literature review that the triazole-based
derivatives are biologically active compounds and fre-
quently synthesized by using conventional technique.
rent work to synthesize triazole derivatives. Our group
has a unique practice on the synthesis of triazole-based
derivatives by using conventional as well as microwave-
assisted synthetic techniques.[8,15]
The current designed product is the continuation of
our previous work in order to optimize the reaction time,
purity of product, economical and finally the yield by fol-
lowing the reaction condition by simple stirring and by
using a microwave instrument. The aimed library of
J Heterocycl Chem. 2019;1–16.
wileyonlinelibrary.com/journal/jhet
© 2019 John Wiley & Sons, Ltd.
1

2
VIRK ET AL.
compounds was synthesized successfully by following
both synthetic strategies. The better yield and minimum
time revealed that the microwave-assisted technique is
more powerful tool for effective synthesis of such hetero-
cyclic compounds as compared with the conventional
method.[16,19] The whole library of synthesized com-
pounds was synthesized within 30 to 70 seconds compar-
ative to the conventional method which has taken 10 to
15 hours (Table 2).
compounds were subjected to the evaluation of their
enzyme inhibition potential. A comparative study of con-
ventional as well as microwave-assisted method was carried
in order to judge the time span of reaction completion and
yield of the synthesized compounds. It was experienced that
all the compounds (9a-r) were synthesized in 33 to
90 seconds with 82% to 97% yield under microwave-assisted
method. The results showed that the microwave-assisted
methodology is better than the conventional because the
conventional methodology is lazy in synthesis and also with
less yield output as shown in the Table 2.
2 | RESULTS AND DISCUSSIONS
A
series of propanamides bearing piperidine and
2.1 | Chemistry
1,2,4-triazole ring were synthesized through conventional
and microwave-assisted methods. Compounds 9a-r were
synthesized by following a series of five steps. The steps A-C
involved the synthesis of 1,2,4-triazole nucleus through the
subsequent synthesis of carboxylate (3) and hydrazide (4).
The step D was based on the synthesis of propanamides 8a-
r, and finally, hybrids of triazole nucleus 9a-r were synthe-
sized by conventional as well as microwave-assisted tech-
niques in steps E and F, respectively. The protocol of
synthesis is given in Scheme 1, and the different analogues
are given in Table 1. Furthermore, the synthesized
For single compound discussion, one of the synthesized
compounds,
N-(3,5-dimethylphenyl)-2-[(5-{1-[(4-
methoxyphenyl)sulfonyl]-4-piperidinyl}-4-methyl-4H-1,2,4-
triazol-3-yl)sulfanyl]propanamide (9f), is chosen. It was
attained as off white amorphous solid with yield of 77%
and 94% with conventional and microwave-assisted pro-
cesses, respectively. The structures of all the derived com-
pounds were confirmed by various spectroscopic
1
techniques like H-NMR, 13C-NMR, and IR. The detailed
description of 9f is given below. The different aromatic
O
O
O
O
O
S
O
S
HN
N
(A)
Cl
+
OC2H5
OC2H5
H3CO
H3CO
3
2
1
(B)
O
O
O
O
O
S
S
N
N
N
(C)
N
NH2
NH
SH
H3CO
H3CO
N
4
5
CH3
CH3
Br
H3C
Br
H
N
(D)
O
Br
R
7
SCHE ME 1 Synthesis of N-
O
substituted-2-[(5-{1-[(4-methoxyphenyl)
sulfonyl]-4-piperidinyl}-4-phenyl-4H-
1,2,4-triazol-3-yl)sulfanyl]propanamide (9a-
r). Reagents and conditions: (A) H2O, 5%
Na2CO3 soln., pH = 9-10, stirring at RT;
(B) NH2NH2.H2O, MeOH, refluxing;
(C) i. MeNCS, EtOH, refluxing, ii. 10%
KOH, refluxing; (D) H2O, 5% Na2CO3 soln.,
pH = 9-10, stirring at RT; (E) DMF, LiH,
stirring at RT; (F) DMF, LiH, microwaves
8a-r
NH2
R
(E)
(F)
6a-r
O
O
S
H3C
H
N
N
N
H
NH
S
H3CO
H
R
N
CH3
H
O
9a-r

VIRK ET AL.
3
TABLE 1 Different synthesized analogues, 9a-r
C.
9a
Structure
C.
9b
Structure
O
O
O
O
CH3
2'''
2'''
S
S
H3C
O
H3C
O
CH3
CH3
CH3
3
N
3
N
1
3' 1'
5'
1
3''
5''
3' 1'
5'
3''
1''
1'''
H3CO
1'''
H3CO
5
5
3'''
3'''
N
1''
5''
N
S
S
N
N
H
H
CH
4''' 3
CH
4''' 3
N
N
N
N
O
O
9c
9d
O
O
2'''
CH3
2'''
CH3
S
S
H3C
O
H3C
O
N
3
N
3
3' 1'
5'
1
3''
5''
3' 1'
5'
1
3''
1'''
H3CO
1'''
H3CO
5
5
3'''
3'''
N
1''
N
1''
5''
S
S
S
N
H
CH3
CH3
N
H
CH
4''' 3
CH
4''' 3
N
N
N
N
N
CH3
O
O
CH3
O
O
9e
9g
9f
CH3
2'''
CH3
2'''
S
S
CH3
N
3
N
1
3
3' 1'
5'
1
3''
5''
3' 1'
5'
3''
5''
O
O
1'''
1'''
H3CO
5
5
3'''
3'''
N
1''
N
1''
S
N
H
H3CO
N
CH3
H
CH
4''' 3
CH
4''' 3
N
N
N
O
O
O
O
9h
2'''
2'''
CH
S
S
H C
3
C2H5
O
CH3
N
3
3
N
3
3
3' 1'
5'
1
3''
3' 1'
1
3''
O
1'''
1'''
H3CO
5
5
5'
3'''
S
5
N
1''
3'''
N
1''
5''
5''
S
H CO
3
N
H
N
H
CH
3
CH
NO
4''' 3
N
N
4'''
2
N
N
CH3
O
O
9i
9k
9m
9j
9l
O
O
2'''
CH3
2'''
CH3
S
S
H3C
H3COOC
N
N
1
3
3' 1'
5'
1
3''
3' 1'
5'
3''
5''
O
O
1'''
H3CO
1'''
H3CO
5
3'''
N
1''
3'''
N
1''
5''
S
S
N
CH3
N
H
H
CH
4''' 3
CH
N
N
4''' 3
N
2'''
N
O
O
CH3
O
O
2'''
S
S
CH3
CH3
CH3
N
1
3
3
N
1
3
3' 1'
5'
3''
5''
3' 1'
5'
3''
O
O
1'''
H3CO
1'''
H3CO
5
5
5
3'''
3'''
N
1''
5''
N
1''
S
S
N
H
N
H
CH
4''' 3
CH
4''' 3
N
N
N
N
N
O
O
9n
O
O
2'''
2'''
CH3
S
S
C2H5
O
H3CO
O
CH3
N
N
1
3
3
3
3' 1'
5'
1
3''
3' 1'
5'
3''
1'''
H3CO
1'''
H3CO
5
5
5
3'''
3'''
N
1''
N
1''
3''
5''
5''
S
S
N
N
H
H
CH
4''' 3
CH
4''' 3
N
N
N
O
O
9o
9q
9p
9r
O
O
2'''
CH3
2'''
CH3
S
S
OC2H5
N
N
3
3' 1'
5'
1
3''
3' 1'
5'
1
O
O
1'''
H3CO
N
1''
5''
5
1'''
H3CO
3'''
N
1''
S
3'''
5''
S
N
N
H
H
CH3
4'''
CH
4''' 3
N
N
N
N
N
O
O
O
O
2'''
2'''
S
S
CH3
CH3
N
N
3
3' 1'
5'
1
3' 1'
5'
1
3''
1''
5''
O
O
N
N
N
1'''
H3CO
1'''
H3CO
5
S
3'''
S
3'''
N
H
N
3''
1''
5''
H
CH3
4'''
CH3
4'''
N
N
1
and aliphatic protons were confirmed by H-NMR spectra
(Figures 1 and 2). At 9.81 ppm, a single peak confirmed
the single proton of NH of amide group. Out of four, the
two aromatic protons at position 20 and 60 of sulfonyl moi-
ety resonated as doublet at 7.74 ppm with J value of 8.8 Hz
and remaining two protons at position 30 and 50 also reso-
nated as doublet at 7.02 ppm having J value of 8.8 Hz. The
other three aromatic protons containing amide linkage res-
onated as two singlet at 7.72 and 6.73 of 2H (H-200, H-600)
and 1H (H-400), respectively. A quartet of one proton H-3000
attached with carbon which is directly attached with car-
bonyl group appeared at 4.47 ppm with J = 7.2 Hz. Three
protons of methoxy group and six protons of methyl
groups attached with benzene ring were appeared as sin-
glet at 3.90 and 2.28 ppm, respectively. The three protons
of methyl group binding with nitrogen of triazole were
confirmed as singlet at 3.42 ppm. The confirmation of
piperidine ring was indicated through the appearance of
four multiplet of nine protons at 3.86 to 3.83 (m, 2H, He-2,
He-6), 2.62 to 2.61 (m, 1H, H-4), 2.54 to 2.52 (m, 2H, Ha-2,

4
VIRK ET AL.
TABLE 2 Comparison of
conventional microwave-assisted
methods
Reaction Time
Reaction Yield %
Compounds
Conventional, h
Microwave, s
Conventional
Microwave
9a
9b
9c
9d
9e
9f
11
12
10
14
12
06
10
11
13
17
08
12
15
12
10
08
11
10
41
44
39
57
90
63
45
68
42
53
37
39
42
49
33
58
55
56
45
52
58
73
59
77
64
75
80
49
66
64
55
83
64
65
72
73
85
87
82
93
97
94
90
92
89
86
90
92
94
91
94
90
85
92
9g
9h
9i
9j
9k
9l
9m
9n
9o
9p
9q
9r
Ha-6), and 2.08 to 1.97 (m, 4H, He-3, He-5, Ha-3, Ha-5).
Three protons of methyl group attached with methine
group resonated as doublet having a J value of 7.2 Hz at
1.64 ppm. The spectral information of 13C spectroscopy
was also used to confirm the structure of the compound
under discussion (Figures 3–5), as 13C spectrum acts as
blue print of compound. The quaternary carbons present
in the compound were confirmed by the peaks appearing
at 169.04 (C-40), 163.09 (C-50000), 157.45 (C-30000), 151.55 (C-
60000), 138.66 (C-300, C-500), 138.09 (C-10000), and 127.80 (C-10).
The aromatic methine carbons in the vicinity of sulfonyl
group resonated at 129.80 (C-20, C-60) and 114.28 (C-30, C-
50) and that in the vicinity of amide linkage at 125.83 (C-
400) and 117.54 (C-200, C-600). The piperidine ring carbons
were confirmed by peaks at positions 45.59 (C-2, C-6),
32.19 (C-4), and 29.13 (C-3, C-5). The carbon of methoxy
group appeared at 55.63, and the carbons of four different
positioning methyl groups were confirmed by peaks at
44.38 (C-3000), 30.12 (C-2000), 21.39 (C-5000, C-6000), and 16.44
(C-4000).
conversion of acetylcholine to choline which in response
terminates the acetylcholine at cholinergic synapses.[3]
The synthesized hybrids (9a-r) of triazole were evaluated
for their potential against AChE enzyme, and their IC50
values are given in Table 3. The aim behind the current
evaluation was the securitization of the active compound
against AChE enzyme. The reference standard used in
this case was Eserine. All the compounds possessed vari-
able potential that was too high as compared with the
standard. However, these compounds with the presented
variety of potential against AChE have the ability to act
as high ranked inhibitors of AChE.
Molecular docking study was carried out to find the
binding orientation of compound 9m with the protein
in action of AChE enzyme. The ligand 9m showed
maximum inhibition potential against the AChE
enzyme among all the synthesized compounds of the
concerned series except compounds 9f. SybylX-1.3
(module Surflex-Dock) was used to dock in ligand 9m
to the active site of AChE enzyme (Table 4, Figure 6).
The authenticity of docked compound was checked by
following the redocked into the active cite of AChE.
Donepezil was extracted from the co-crystal complex
4EY7In to validate the docking methodology and then
by re-docking in the same binding pocket. Experimen-
tally, the docking poses were compared with the bind-
ing mode of donepezil in AChE.[5] This indicates that
2.2 | Acetyl cholinesterase inhibition
potential
The AChE belongs to the family of enzymes having ser-
ine hydrolases. The current enzyme is responsible for the

VIRK ET AL.
5
FIGURE 1 1H-NMR spectrum of
compound 9f (aromatic)
FIGURE 2 1H-NMR spectrum of
compound 9f (aliphatic)
our docking procedure is reliable. Moreover, a figure
showed that the inhibitor is showing similar binding
mode as found experimentally in 4EY7 complex. The
graphic study of docked ligand describes that com-
pound 9m penetrates deeply into active cleft (CAS and
PAS) of AChE enzyme. In the active site of AChE, the
ligands have acquired binding position that it has devel-
oped the H-bonding with the backbone of GLY126 and
ALA204. The ethyl group substituted at aromatic ring
attached with amidic group deeply penetrated into the
CAS region where it may have developed the hydropho-
bic interaction responsible for its best activity. The
experimental finding like C scorea, PMF scoree, and
Polar scorec are 4.76, 39.091, and 2.50, respectively. An
array of amino acids like TRP86, Ser203, Trp286,
Phe295, and Phe338 showed the interaction with inhibi-
tor drug for its better efficiency. The variability among
the ligand acceptors interaction may account for poten-
tial inhibition behavior of compound 9m.
2.3 | α-Glucosidase inhibition potential
The potential against α-glucosidase enzyme of presented
compounds 9a-r was performed to find out some active
anti-α-glucosidase compounds for the cure of type 2 dia-
betes (Table 3). The inhibition of this enzyme by acarbose
was used as reference standard. Majority of the com-
pounds were good inhibitors which is the accumulative
effect of the whole molecule. Twelve compounds

6
VIRK ET AL.
FIGURE 3 13C-NMR spectrum of
compound 9f (aliphatic)
FIGURE 4 13C-NMR spectrum of
compound 9f (aromatic-up field)
expressed a very prominent activity as compared with
standard. The compound 9e revealed that it has a mini-
mum IC50 value (27.52 1.28) which means that it has a
maximum inhibition potential as compared with the
whole series of propionamides and also better than the
standard. The compound 9i was observed as least active
than other active compounds because of having the
highest IC50 (342.65 1.17) but more active than aca-
rbose. Six compounds 9b, 9c, 9d, 9j, 9n, and 9o were
reported as inactive. For studying the SAR (structure
activity relationship) between different compounds, it
became evident that only a limited part of molecules is
different from each other which is N-substituted of
propanamide functionality and a remaining part was
intact in all compounds. Among the six regio-isomers, 9a-
f, bearing two methyl groups on phenyl group attached
with propionamide part, 9e, having 3,4-dimethylphenyl
group showed highest inhibitory potential revealed by the
lowest IC50 value. It may be due to less steric hindrance
and more binding sites with enzyme and stable complex.
Among the three isomeric compounds 9j-l containing one
methyl group attached at positions 2, 3, and 4, respectively,
the compound 9k having 3-methyl phenyl group possessed
good activity as compared with other two. The com-
pounds, 9p-r, with phenyl, benzyl, and cyclohexyl respec-
tively without substitution also showed good inhibitory

VIRK ET AL.
7
FIGURE 5 13C-NMR spectrum of
compound 9f (aromatic-down field)
2.4 | BSA binding studies
TABLE 3 Biological potential of all the synthesized
compounds, 9a-r
The comparative BSA binding studies were carried out
on the selective three compounds 9j, 9m, and 9r
(Table 5, Figures 7–12). The selected and designed com-
pounds possess best binding constant values which
guaranteed for their competences of showing binding
with BSA. The compound 9m showed the highest bind-
ing constant value while compound 9r had the least one.
The highest binding constant of 9m may be because
(Figure 8) of an ethyl group substituted at the ortho posi-
tion of the aromatic ring responsible for the highest bind-
ing constant among synthesized series. The calculated kq
was larger than the maximum scattering collision
quenching rate constant (2 × 1010 M−1 s−1) in dynamic
quenching, which indicates that the quenching of BSA
with the derivatives follows a static process, rather than a
dynamic one. When small molecules bind independently
to a set of equivalent sites on a macromolecule, the
apparent constant (Ka) and the number of binding sites
(n) can be calculated using the double reciprocal plot.
The double reciprocal plots of the derivatives are shown
(Figures 7 to 12). The values of Ka and n are obtained
from the intercept and slope of the linear plot,
respectively.
IC50 Values
Compounds
AChE
α-Glucosidase
114.69 1.23
-
9a
278.46 1.27
375.12 1.15
427.61 1.19
439.37 1.24
407.24 1.22
261.42 1.18
315.12 1.38
329.85 1.35
-
9b
9c
-
9d
-
9e
27.52 1.28
129.38 1.34
45.52 1.32
153.47 1.35
342.65 1.17
-
9f
9g
9h
9i
9j
285.71 1.23
315.82 1.27
349.76 1.25
263.54 1.34
384.62 1.17
319.43 1.26
375.16 1.14
-
9k
132.63 1.25
231.37 1.23
146.51 1.14
-
9l
9m
9n
9o
-
9p
154.32 1.27
62.58 1.23
47.48 1.41
9q
9r
-
Eserine
Acarbose
0.19 0.05
3 | EXPERIMENTAL
375.82 1.76
Unless otherwise noted, all the chemical, solvents, and
reagents of analytical grade were availed by the local sup-
plier of brand Sigma Aldrich. Analytical thin layer chro-
matography was used to know about the progress of
potential. The two disubstituted phenyl part with different
substituents in 9h and 9i were reported as active against
α-glucosidase.

8
VIRK ET AL.
TABLE 4 Surflex score of docked ligand, compound 9m for AChE enzyme
Docking complex = AChE-9m
C Scorea
Crash Scoreb
Polar Scorec
D Scored
PMF Scoree
G Scoref
Chem Scoreg
Amino Acid Interaction
4.76
−2.15
2.50
−267.032
39.091
−254.43
−25.858
TRP86
Ser203
Trp286
Phe295
Phe338
aC-score is a consensus scoring which uses multiple types of scoring functions to rank the affinity of ligands.
bCrash-score revealing the inappropriate penetration into the binding site.
cPolar-score region of the ligand.
dD-score for chRe and van der Waals interactions between the protein and the ligand.
ePMF-score indicating the Helmholtz free energies of interactions for protein-ligand atom pairs (Potential of Mean Force, PMF).
fG-score showing hydrogen bonding, complex (ligand-protein), and internal (ligand-ligand) energies.
gChem-score points for hydrogen bonding, lipophilic contact, and rotational entropy, along with an intercept term.
FIGURE 6 Molecular docking generated poses for selected AChE inhibitor (9m); (A) compound 9m bonded within the active site of
AChE enzyme; (B) binding mode of 9m in AChE ligand binding site; (C) 2D-ligand-protein interaction diagram was generated for the best
poses obtained with compound 9m against AChE enzyme. Hydrogen bonding interactions are depicted as blue and green dotted arrows in
H-bond acceptor/donner pattern, respectively. Besides, the π-π interactions are shown as orange line. The amino acids involved making key
interactions with ligand are displayed as purple and green balls
TABLE 5 Stern-Volmer quenching
Compounds
KSV × 101, M−1
3.9573
kq × 1010, M−1 s−1
3.9573
Ka, M−1
5.11 x 104
1.33 x 105
2.43 x 103
N
constants, binding constant, and
number of binding site for compounds
(9j, 9m, 9r)
9j
1.03
1.18
0.84
9m
9r
2.4628
2.4628
1.2197
1.2197
Abbreviations: KSV, Stern-Volmer quenching constant; Kq, apparent bimolecular quenching rate constant;
Ka, apparent constant; N, number of binding sites.
reaction on an aluminum plate coated with silica gel and
fluorescence studies were made by using flourophotometer
(Varioskan Flash 4.00.53). All the comparative data analy-
sis under conventional and microwave-assisted techniques
was presented in tabular form.
1
visualized under irradiation. H-NMR and 13C-NMR were
recorded by Bruker spectrometers operating at 600 and
150 MHz on Bruker AM-400 spectrometer in CDCl3. The
NMR data were interpreted in chemical shift (δ) in ppm
while the signals multiplicities were also indicated. Cou-
pling constant (J) was given in Hz (Hertz). The functional
groups confirmation was made by using IR studies by KBr
pellet method on Jasco-320-A spectrophotometer (wave
number in cm−1). EIMS data were availed by using
JMSHX-110 spectrometer. Griffin and George apparatus
were utilized to calculate the melting points. The
3.1 | Synthesis of ethyl
1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinecarboxylate (3)
Compound 3 was synthesized by room temperature stir-
ring of the 4-methoxybenzenesulfonyl chloride (1;

VIRK ET AL.
9
3.5
3
y = 39573x + 0.9103
2.5
2
R2 = 0.9821
1.5
1
0.5
0
0.00E+00 1.00E-05 2.00E-05 3.00E-05 4.00E-05 5.00E-05 6.00E-05
[Q]
FIGURE 7 Fluorescence graph of BSA in the presence of 9j
FIGURE 10 Stern-Volmer plots of 9j
2
y = 11794x + 1.1585
1.8
R2 = 0.9128
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0
0.00001
0.00002
0.00003
0.00004
0.00005
0.00006
[Q]
FIGURE 8 Fluorescence graph of BSA in the presence of 9m
FIGURE 11 Stern-Volmer plots of 9m
0.06 mol) with ethyl isonipecotate (2; 0.06 mol) in aque-
ous medium with 10% Na2CO3 solution. Analytical TLC
was used to confirm the progress of reaction completion.
At the end point of reaction, neutralization was achieved
by dil. HCl in order to obtain the product as white precip-
itate. The precipitates were filtered by adding chilled
water, washed, and dried at room temperature.[16]
3.2 | Synthesis of
1-(4-methoxyphenylsulfonyl)piperidine-
4-carbohydrazide (4)
The synthesis of compound 4 was processed by refluxing
the reactant 3 (0.05 mol) and hydrazine hydrate for
FIGURE 9 Fluorescence graph of BSA in the presence of 9r

10
VIRK ET AL.
1.8
1.6
1.4
1.2
1
3.5 | Synthesis of N-(substituted)-
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9a-r)
y = 12197x + 1.0149
R2 = 0.994
Method A: For the synthesis of target propanamides
derivatives of 1,2,4-triazole, compound 5 with LiH was
stirred at room temperature in DMF as a solvent. In the
activated compound 5 (0.0005 mol), we added equimolar
amounts of synthesized propanamides (8a-r) which
worked as electrophiles with the aim to obtain the aimed
products, 9a-r. The whole mixture was stirred at room
temperature for 6 to 17 hours. Thin layer chromatogra-
phy was utilized to monitor the reaction conditions and
progress. Finally, the products, 9a-r, were availed
through the addition of chilled distilled water. The target
compounds were acquired in the form of precipitates or
extracts availed by solvent extraction. The precipitates
were washed, dried, and stored for further studies. The
extracts were also dried and stored for further studies.
Method B: For the synthesis of target propanamides
derivatives of 1,2,4-triazole, compound 5 with LiH was
stirred at room temperature in DMF as a solvent. In the
activated compound 5 (0.0005 mol), we added equimolar
amounts of synthesized propanamides (8a-r) which
worked as electrophiles with the aim to obtain the aimed
products, 9a-r. The whole mixture was irradiated by the
microwave in microwave oven for 33 to 90 seconds. The
synthesis of the compounds, 9a-r, was performed effi-
ciently in seconds with high purity and yield proving that
the microwave synthetic strategy is more efficient and
attractive. Thin layer chromatography was utilized to
monitor the reaction conditions and progress. Finally,
the products, 9a-r, were availed through the addition of
chilled distilled water. The target compounds were
acquired in the form of precipitates or extracts availed by
solvent extraction. The precipitates were washed, dried,
and stored for further studies. The extracts were also
dried and stored for further studies.
0.8
0.6
0.4
0.2
0
0
0.00001 0.00002 0.00003 0.00004 0.00005 0.00006
[Q]
FIGURE 12 Stern-Volmer plots of 9r
4 hours in the presence of methanol. After product con-
firmation by TLC, the excess solvent was evaporated, and
precipitates of title compound were achieved by the addi-
tion of chilled water. The precipitates were filtered,
washed, and dried.[16]
3.3 | Synthesis of
5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazole-
3-thiol (5)
The title compound was synthesized by the reflux reac-
tion of equimolar (0.0308 mol) quantities of compound
4 and methyl isothiocyanate for 1 hour. The formed
intermediate was further refluxed for 1 hour with equi-
molar KOH. The progress of reaction was checked by
TLC. On the reaction completion, the pH was adjusted at
4 to 5 by the addition of dil. HCl with continuous stirring.
The title compound was precipitated, filtered, washed,
and dried for further reaction.[16]
3.4 | Synthesis of N-(substituted)-
2-bromopropanamides (8a-r)
3.5.1 | 5-{1-[(4-Methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazole-
3-thiol (5)
A library of aralkyl/aryl amines (6a-r; 0.02 mol) and
2-bromopropionyl bromide (7; 0.02 mol) was reacted in
distilled water on stirring for 1 to 2 hours. The pH was
maintained at 9 to 10 by aqueous Na2CO3 solution. The
amides in the various physical forms and colors were pre-
cipitated, filtered, washed, dried, and stored in low tem-
perature environment for further reactions.[16]
IR (KBr, wave number, cm−1): 2800 (Ar C–H), 1611
1
(C N), 1529 (Ar C C), 1312 (S O), 721 (C–H); H-NMR
(CDCl3, 600 MHz, δ [ppm]): 13.52 (s, 1H, SH), 7.70 (d,
J = 8.8 Hz, 2H, H-20, H-60), 7.17 (d, J = 8.8 Hz, 2H, H-30,
H-50), 3.86 (s, 3H, H-10000), 3.63-3.61 (m, 2H, He-2, He-6),
3.37 (s, 3H, H-2000), 2.83-2.80 (m, 1H, H-4), 2.38-2.35 (m,

VIRK ET AL.
11
2H, Ha-2, Ha-6), 1.97-1.95 (m, 2H, He-3, He-5), 1.66-1.59
(m, 2H, Ha-3, Ha-5); 13C-NMR (CDCl3, 150 MHz, δ
[ppm]): 166.61 (C-40), 162.63 (C-5000), 154.31 (C-3000), 129.63
(C-20, C-600), 126.63 (C-10), 114.42 (C-30, C-50), 55.63 (C-1000),
45.29 (C-2, C-6), 30.82 (C-4), 29.58 (C-2000), 28.13 (C-3, C-5).
(C-40), 163.07 (C-50000), 157.44 (C-30000), 151.55 (C-60000), 134.38
(C-100), 133.56 (C-200), 131.07 (C-600), 129.81 (C-20, C-60),
129.28 (C-10), 127.80 (C-400), 126.89 (C-500), 122.37 (C-300),
101004.28 (C-30, C-50), 55.63 (C-1000), 45.46 (C-2, C-6), 43.82 (C-
3 ), 31.85 (C-4), 30.03 (C-2000), 29.08 (C-3, C-5), 20.80 (C-
5000), 17.99 (C-6000), 16.61 (C-4000).
3.5.2 | N-(2,3-Dimethylphenyl)-
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9a)
3.5.4 | N-(2,5-Dimethylphenyl)-
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9c)
White amorphous solid; yield: 88%; M.P: 190.0ꢀC; HRMS:
[M]•+ 543.1959 (Calcd. for C26H33N5O4S2; 543.1974); IR
(KBr, wave number, cm−1): 3339 (N-H), 2850 (Ar C–H),
1710 (C O), 1650 (C N), 1520 (Ar C C), 1372 (CH3),
Off white amorphous solid; yield: 88%; M.P: 175ꢀC;
HRMS: [M]•+ 543.1959 (Calcd. for C26H33N5O4S2;
543.1974); IR (KBr, wave number, cm−1): 3340 (N-H),
2800 (Ar C–H), 1650 (C O), 1600 (C N), 1510
(Ar C C), 1370 (CH3), 1200 (S O), 1250 (C–O–C),
1
1275 (S O), 1150 (C–O–C), 650 (C–H); H-NMR (CDCl3,
600 MHz, δ [ppm]): 9.43 (s, 1H, NH), 7.74 (d, J = 8.7 Hz,
2H, H-20, H-60), 7.60 (d, J = 7.9 Hz, 1H, H-600), 7.06
(t, J = 7.7 Hz, 1H, H-500), 7.03 (d, J = 8.7 Hz, 2H, H-30, H-
50), 6.98 (d, J = 7.4 Hz, 1H, H-400), 4.57 (q, J = 7.3 Hz, 1H,
H-3000), 3.90 (s, 3H, H-1000), 3.85-3.81 (m, 2H, He-2, He-6),
3.43 (s, 3H, H-2000), 2.65-2.62 (m, 1H, H-4), 2.57-2.54 (m,
2H, Ha-2, Ha-6), 2.29 (s, 3H, H-5000), 2.10 (s, 3H, H-60000),
2.08-1.96 (m, 4H, He-3, He-5, Ha-3, Ha-5), 1.67 (d,
J = 7.3 Hz, 3H, H-4000); 3C-NMR (CDCl3, 150 MHz, δ
[ppm]): 169.52 (C-40), 163.07 (C-5000), 157.47 (C-300), 151.53
(C-600), 137.25 (C-10), 135.78 (C-200), 128.80 (C-20, C-60),
129.01 (C-10), 127.81 (C-300), 126.90 (C-600), 120005.59 (C-500),
121.19 (C-400), 114.27 (C-30, C-500), 55.63 (C-1000), 45.53 (C-
2, C-6), 43.97 (C-3000), 32.05 (C-4), 30.05 (C-2 ), 29.11 (C-
3, C-5), 20.61 (C-5000), 16.70 (C-6000), 13.74 (C-4000).
1
750 (C–H); H-NMR (CDCl3, 600 MHz, δ [ppm]): 9.40 (s,
1H, NH), 7.76 (s, 1H, H-600), 7.73 (d, J = 8.8 Hz, 2H, H-20,
H-60), 7.02 (d, J = 8.8 Hz, 2H, H-30, H-50), 6.86-6.84 (m,
2H, H-300, H-400), 4.60 (q, J = 7.2 Hz, 1H, H-3000), 3.90 (s,
3H, H-1000), 3.82-3.80 (m, 1H, He-2), 3.74-3.72 (m, 1H, He-
6), 3.42 (s, 3H, H-2000), 2.67-2.64 (m, 1H, H-4), 2.62-2.57
(m, 2H, Ha-2, Ha-6), 2.30 (s, 3H, H-5000), 2.17 (s, 3H, H-
6000), 2.11-2.07 (m, 4H, He-3, He-5, Ha-3, Ha-5), 1.68 (d,
J = 7.2 Hz, 3H, H-4000); 13C-NMR (CDCl3, 150 MHz, δ
[ppm]): 169.40 (C-40), 163.07 (C-50000), 157.46 (C-30000),
151.58 (C-60000), 136.09 (C-100), 135.98 (C-200), 130.19 (C-600),
129.81 (C-20, C-60), 127.77 (C-10), 125.98 (C-500), 125.43 (C-
300), 122.76 (C-400), 114.28 (C-30, C-50), 55.63 (C-1000), 45.46
(C-2, C-6), 43.71 (C-3000), 31.81 (C-4), 30.01 (C-2000), 29.09
(C-3, C-5), 21.13 (C-4000), 17.65 (C-5000), 16.56 (C-4000).
3.5.3 | N-(2,4-Dimethylphenyl)-
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9b)
3.5.5 | N-(2,6-Dimethylphenyl)-
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9d)
Gray white amorphous solid; yield: 90%; M.P: 153ꢀC;
HRMS: [M]•+ 543.1959 (Calcd. for C26H33N5O4S2;
543.1974); IR (KBr, wave number, cm−1): 3341 (N–H),
2800 (Ar C–H), 1650 (C O), 1600 (C N), 1520 (Ar C C),
Off white amorphous solid; yield: 90%; M.P: 231.0ꢀC;
HRMS: [M]•+ 543.1959 (Calcd. for C26H33N5O4S2;
543.1974); IR (KBr, wave number, cm−1): 3340 (N–H),
2800 (Ar C–H), 1690 (C O), 1610 (C N), 1520
(Ar C C), 1300 (CH3), 1270 (S O), 1125 (C–O–C),
1
1370 (CH3), 1300 (S O), 1210 (C–O–C), 700 (C–H); H-
NMR (CDCl3, 600 MHz, δ [ppm]): 9.34 (s, 1H, NH), 7.76
(s, 1H, H-300), 7.74 (d, J = 8.4 Hz, 2H, H-20, H-60), 7.03 (d,
J = 8.0 Hz, 2H, H-30, H-50), 6.98-6.96 (m, 2H, H-500, H-600),
4.58 (q, J = 6.9 Hz, 1H, H-3000), 3.90 (s, 3H, H-1000), 3.83-3.81
(m, 1H, He-2), 3.75-3.73 (m, 1H, He-6), 3.42 (s, 3H, H-2000),
2.66-2.63 (m, 1H, H-4), 2.60-2.57 (m, 2H, Ha-2, Ha-6), 2.28
(s, 3H, H-5000), 2.16 (s, 3H, H-6000), 2.10-2.07 (m, 1H, He-3),
2.02-1.96 (m, 3H, He-5, Ha-3, Ha-5), 1.67 (d, J = 7.2 Hz,
3H, H-4000); 13C-NMR (CDCl3, 150 MHz, δ [ppm]): 169.33
1
730 (C–H); H-NMR (CDCl3, 600 MHz, δ [ppm]): 9.30 (s,
1H, NH), 7.74 (d, J = 8.8 Hz, 2H, H-20, H-60), 7.08-7.03
(m, 3H, H-300, H-400, H-500), 7.02 (d, J = 8.7 Hz, 2H, H-30,
H-50), 4.57 (q, J = 7.3 Hz, 1H, H-3000), 3.88 (s, 3H, H-1000),
3.81-3.78 (m, 2H, He-2, He-6), 3.47 (s, 3H, H-2000),
2.69-2.65 (m, 1H, H-4), 2.62-2.58 (m, 2H, Ha-2, Ha-6), 2.07
(s, 6H, H-5000, H-6000), 2.06-1.99 (m, 4H, He-3, He-5, Ha-3,
Ha-5), 1.69 (d, J = 7.3 Hz, 3H, H-4000); 13C-NMR (CDCl3,

12
VIRK ET AL.
150 MHz, δ [ppm]): 169.59 (C-40), 163.08 (C-50000), 157.33
(C-30000), 151.54 (C-60000), 135.32 (C-100), 133.91 (C-200, C-600),
129.79 (C-20, C-60), 128.00 (C-300, C-500), 102007.79 (C-10),
127.06 (C-400), 114.28 (C-30, C-50), 55.62 (C-1 ), 45.42 (C-
2, C-6), 43.90 (C-3000), 31.93 (C-4), 31.32 (C-2000), 29.05 (C-
3, C-5), 18.14 (C-5000, C-6000).
150 MHz, δ [ppm]): 169.04 (C-40), 163.09 (C-50000), 157.45
(C-30000), 151.55 (C-60000), 138.66 (C-300, C-500), 138.09 (C-100),
129.80 (C-20, C-60), 127.80 (C-10), 125.83 0(0C0 -400), 117.54 (C-
200, C-600), 114.28 (C-30, C-50), 55.63 (C-1 ), 45.59 (C-2, C-
6), 44.38 (C-3000), 32.19 (C-4), 30.12 (C-2000), 29.13 (C-3, C-
5), 21.39 (C-5000, C-6000), 16.44 (C-4000).
3.5.6 | N-(3,4-Dimethylphenyl)-
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9e)
3.5.8 | N-(2-Ethyl-6-methylphenyl)-
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9g)
Off white amorphous solid; yield: 90%; M.P: 189.2ꢀC;
HRMS: [M]•+ 543.1959 (Calcd. for C26H33N5O4S2;
543.1974); IR (KBr, wave number, cm−1): 3341 (N–H),
2820 (Ar C–H), 1650 (C O), 1600 (C N), 1520
White amorphous solid; yield: 89%; M.P: 202.3ꢀC; HRMS:
[M]•+ 557.2120 (Calcd. for C27H35N5O4S2; 557.2130); IR
(KBr, wave number, cm−1): 3339 (N–H), 2825 (Ar C–H),
1700 (C O), 1610 (C N), 1525 (Ar C C), 1350 (CH3),
1250 (S O), 1150 (C–O–C), 720 (C–H); 1H-NMR (CDCl3,
600 MHz, δ [ppm]): 9.26 (s, 1H, NH), 7.74 (d, J = 8.8 Hz,
2H, H-20, H-60), 7.13 (t, J = 7.5 Hz, 1H, H-400), 7.06-7.03
(m, 2H, H-300, H-500), 7.01 (d, J = 8.8 Hz, 2H, H-30, H-50),
4.60 (q, J = 7.3 Hz, 1H, H-3000), 3.88 (s, 3H, H-1000),
3.81-3.77 (m, 2H, He-2, He-6), 3.48 (s, 3H, H-2000),
2.68-2.63 (m, 1H, H-4), 2.61-2.59 (m, 2H, Ha-2, Ha-6), 2.46
(q, J = 7.5 Hz, 2H, H-6000), 2.11 (s, 3H, H-5000), 2.08-2.01
(m, 4H, He-3, He-5, Ha-3, Ha-5), 1.68 (d, J = 7.3 Hz, 3H,
H-4000), 1.04 (t, J = 7.2 Hz, 3H, H-7000); 13C-NMR (CDCl3,
150 MHz, δ [ppm]): 169.83 (C-40), 163.08 (C-50000), 157.34
(C-30000), 151.55 (C-60000), 141.13 (C-100), 135.79 (C-200),
133.27 (C-600), 129.81 (C-20, C-60), 128.20 (C-10), 128.06 (C-
300), 127.41 (C-400), 126.37 (C-500), 114.30 (C-30, C-50), 55.61
(C-1000), 45.41 (C-2, C-6), 43.74 (C-3000), 31.93 (C-4), 30.12
(C-2000), 29.06 (C-3, C-5), 24.78 (C-6000), 18.15 (C-5000), 17.00
(C-4000), 14.55 (C-7000).
1
(Ar C C), 1310 (S O), 1200 (C–O–C), 630 (C–H); H-
NMR (CDCl3, 600 MHz, δ [ppm]): 9.92 (s, 1H, NH), 7.75
(d, J = 8.8 Hz, 2H, H-20, H-60), 7.36-7.36 (m, 1H, H-600),
7.30-7.29 (m, 1H, H-500), 7.05 (s, 1H, H-200), 7.03 (d,
J = 8.7 Hz, 2H, H-30, H-50), 4.46 (q, J = 7.2 Hz, 1H, H-
3000), 3.90 (s, 3H, H-1000), 3.86-3.82 (m, 2H, He-2, He-6), 3.42
(s, 3H, H-2000), 2.63-2.61 (m, 1H, H-4), 2.63-2.55 (m, 2H,
Ha-2, Ha-6), 2.23 (s, 3H, H-5000), 2.21 (s, 3H, H-6000),
2.10-1.98 (m, 4H, He-3, He-5, Ha-3, Ha-5), 1.66 (d,
J = 7.0 Hz, 3H, H-4000); 13C-NMR (CDCl3, 150 MHz, δ
[ppm]): 168.85 (C-40), 163.08 (C-50000), 157.41 (C-30000),
151.59 (C-60000), 137.05 (C-100), 135.99 (C-300), 132.37 (C-400),
129.81 (C-20, C-60), 127.80 (C-10), 120.89 (C-600), 117.12 (C-
200), 115.87 (C-500), 114.27 (C-30, C-50), 55.63 (C-1000), 45.56
(C-2, C-6), 44.26 (C-3000), 32.14 (C-4), 30.10 (C-2000), 29.09
(C-3, C-5), 19.81 (C-5000), 19.15 (C-6000), 16.41 (C-4000).
3.5.7 | N-(3,5-Dimethylphenyl)-
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9f)
3.5.9 | N-(2-Methyl-6-nitrophenyl)-
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9h)
Off white amorphous solid; yield: 87%; M.P: 190.3ꢀC;
HRMS: [M]•+ 543.1959 (Calcd. for C26H33N5O4S2;
543.1974); IR (KBr, wave number, cm−1): 3341 (N–H),
2830 (Ar C–H), 1710 (C O), 1620 (C N), 1530
(Ar C C), 1310 (CH3), 1230 (S O), 1140 (C–O–C),
Light yellow amorphous solid; yield: 89%; M.P: 175ꢀC;
HRMS: [M]•+ 574.1659 (Calcd. for C25H30N6O6S2;
574.1668); IR (KBr, wave number, cm−1): 3340 (N–H),
2820 (Ar C–H), 1670 (C O), 1600 (C N), 1500
(Ar C C), 1350 (CH3), 1310 (S O), 1200 (C–O–C),
1
715 (C–H); H-NMR (CDCl3, 600 MHz, δ [ppm]): 9.81 (s,
1
1H, NH), 7.74 (d, J = 8.8 Hz, 2H, H-20, H-60), 7.72 (s, 2H,
H-200, H-600), 7.02 (d, J = 8.8 Hz, 2H, H-30, H-50), 6.73 (s,
1H, H-400), 4.47 (q, J = 7.2 Hz, 1H, H-3000), 3.90 (s, 3H, H-
1000), 3.86-3.83 (m, 2H, He-2, He-6), 3.42 (s, 3H, H-2000),
2.62-2.61 (m, 1H, H-4), 2.54-2.52 (m, 2H, Ha-2, Ha-6), 2.28
(s, 6H, H-5000, H-6000), 2.08-1.97 (m, 4H, He-3, He-5, Ha-3,
Ha-5), 1.64 (d, J = 7.2 Hz, 3H, H-4000); 13C-NMR (CDCl3,
690 (C–H); H-NMR (CDCl3, 600 MHz, δ [ppm]): 10.07
(s, 1H, NH), 7.74 (d, J = 8.5 Hz, 2H, H-20, H-60), 7.46 (m,
2H, H-300, H-500), 7.26 (t, J = 7.7 Hz, 1H, H-400), 7.01 (d,
J = 8.1 Hz, 2H, H-30, H-50), 4.60 (q, J = 7.2 Hz, 1H, H-
3000), 3.89 (s, 3H, H-1000), 3.82-3.79 (m, 2H, He-2, He-6), 3.49
(s, 3H, H-2000), 2.70-2.68 (m, 1H, H-4), 2.62-2.58 (m, 2H,
Ha-2, Ha-6), 2.29 (s, 6H, H-5000, H-6000), 2.11-2.05 (m, 4H,

VIRK ET AL.
13
He-3, He-5, Ha-3, Ha-5), 1.66 (d, J = 7.1 Hz, 3H, H-4000);
13C-NMR (CDCl3, 150 MHz, δ [ppm]): 169.67 (C-40),
163.05 (C-50000), 157.57 (C-30000), 151.40 (C-60000), 146.15 (C-
100), 137.62 (C-200), 135.06 (C-600), 129.82 (C-20, C-60),
128.77 (C-10), 127.77 (C-300), 126.53 (C-500), 122.52 (C-400),
114.26 (C-30, C-50), 63.72 (C-5000), 55.62 (C-1000), 45.48 (C-2,
C-6), 43.48 (C-3000), 31.95 (C-4), 30.19 (C-2000), 29.01 (C-3,
C-5), 18.49 (C-5000, C-6000), 16.52 (C-4000).
(s, 3H, H-5000), 2.11-2.06 (m, 2H, He-3, He-5), 2.03-1.96 (m,
2H, Ha-3, Ha-5), 1.67 (d, J = 7.2 Hz, 3H, H-4000); 13C-NMR
(CDCl3, 150 MHz, δ [ppm]): 166.99 (C-40), 163.08 (C-50000),
159.01 (C-30000), 157.73 (C-60000), 136.15 (C-100), 130.42 (C-200),
129.80 (C-20, C-60), 129.29 (C-10), 128.00 (C-600), 126.42 (C-
300), 010024.88 (C-500), 122.39 (C-400), 114.28 (C-30, C-50), 55.63
(C-1 ), 45.34 (C-2, C-6), 43.78 (C-3000), 31.83 (C-4), 30.02
(C-2000), 28.99 (C-3, C-5), 18.11 (C-5000), 16.56 (C-400‘).
3.5.10 | Methyl
3.5.12 | 2-[(5-{1-[(4-Methoxyphenyl)
sulfonyl]-4-piperidinyl}-4-methyl-4H-
1,2,4-triazol-3-yl)sulfanyl]-N-
2-({2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanoyl}amino)-
5-methylbenzoate (9i)
(3-methylphenyl)propanamide (9k)
Off white amorphous solid; yield: 86%; M.P: 170ꢀC;
HRMS: [M]•+ 529.1809 (Calcd. for C25H31N5O4S2;
529.1817); IR (KBr, wave number, cm−1): 3338 (N–H),
2800 (Ar C–H), 1680 (C O), 1600 (C N), 1510
(Ar C C), 1370 (CH3), 1350 (S O), 1200 (C–O–C),
White amorphous solid; yield: 85%; M.P: 167.0ꢀC; HRMS:
[M]•+ 587.1864 (Calcd. for C27H33N5O6S2; 587.1872); IR
(KBr, wave number, cm−1): 3340 (N–H), 2820 (Ar C–H),
1690 (C O), 1600 (C N), 1500 (Ar C C), 1310 (CH3),
1
1
1250 (S O), 1150 (C–O–C), 690 (C-H); H-NMR (CDCl3,
770 (C–H); H-NMR (CDCl3, 600 MHz, δ [ppm]): 9.92 (s,
600 MHz, δ [ppm]): 7.73 (d, J = 8.8 Hz, 2H, H-20, H-60),
7.42 (d, J = 7.2 Hz, 1H, H-600), 7.37-7.34 (m, 1H, H-500),
7.23 (s, 1H, H-300), 7.02 (d, J = 8.9 Hz, 2H, H-30, H-50),
4.35 (q, J = 7.3 Hz, 1H, H-3000), 3.90 (s, 3H, H-1000),
3.85-3.83 (m, 2H, He-2, He-6), 3.51 (s, 3H, H-5000), 3.40 (s,
3H, H-2000), 3.26 (s, 3H, H-6000), 2.66-2.58 (m, 3H, H-4, Ha-
2, Ha-6), 2.07-1.89 (m, 4H, He-3, He-5, Ha-3, Ha-5), 1.60
(d, J = 7.1 Hz, 3H, H-4000); 13C-NMR (CDCl3, 150 MHz, δ
[ppm]): 168.52 (C-40), 163.17 (C-70000), 163.01 (C-50000),
155.28 (C-30000), 152.61 (C-200), 138.53 (C-100), 137.89 (C-400),
129.81 (C-10), 129.75 (C-20, C-60), 128.66 (C-600), 128.05 (C-
300), 127.46 (C-500), 114.26 (C-30, C-50), 55.62 (C-1000), 48.23
(C-5000), 45.39 (C-2, C-6), 45.53 (C-3000), 31.76 (C-4), 28.99
(C-3, C-5), 28.48 (C-2000), 16.88 (C-4000), 14.98 (C-6000).
1H, NH), 7.75 (d, J = 8.8 Hz, 2H, H-20, H-60), 7.74 (s, 1H,
H-200), 7.36 (d, J = 8.1 Hz, 1H, H-600), 7.17 (t, J = 7.7 Hz,
1H, H-500), 7.02 (d, J = 8.8 Hz, 2H, H-30, H-50), 6.90 (d,
J = 7.5 Hz, 2H, H-400), 4.47 (q, J = 7.2 Hz, 1H, H-3000), 3.90
(s, 3H, H-1000), 3.86-3.82 (m, 2H, He-2, He-6), 3.42 (s, 3H,
H-2000), 2.63-2.62 (m, 1H, H-4), 2.56-2.54 (m, 2H, Ha-2, Ha-
6), 2.33 (s, 3H, H-5000), 2.10-1.98 (m, 4H, He-3, He-5, Ha-3,
Ha-5), 1.66 (d, J = 7.3 Hz, 3H, H-4000); 13C-NMR (CDCl3,
150 MHz, δ [ppm]): 169.05 (C-40), 163.09 (C-50000), 157.45
(C-30000), 151.60 (C-60000), 138.76 (C-100), 138.20 (C-300),
129.82 (C-20, C-60), 128.66 (C-600), 127.78 (C-10), 124.87 (C-
200), 120.23 (C-500), 116.76 (C-400), 114.28 (C-30, C-50), 55.64
(C-1000), 45.57 (C-2, C-6), 44.29 (C-3000), 32.15 (C-4), 30.11
(C-2000), 29.10 (C-3, C-5), 21.46 (C-5000), 16.41 (C-4000).
3.5.11 | 2-[(5-{1-[(4-Methoxyphenyl)
sulfonyl]-4-piperidinyl}-4-methyl-4H-
1,2,4-triazol-3-yl)sulfanyl]-N-
3.5.13 | 2-[(5-{1-[(4-Methoxyphenyl)
sulfonyl]-4-piperidinyl}-4-methyl-4H-
1,2,4-triazol-3-yl)sulfanyl]-N-
(2-methylphenyl)propanamide (9j)
(4-methylphenyl)propanamide (9l)
White amorphous solid; yield: 88%; M.P: 196.5ꢀC; HRMS:
[M]•+ 529.1809 (Calcd. for C25H31N5O4S2; 529.1817); IR
(KBr, wave number, cm−1): 3341 (N–H), 2810 (Ar C–H),
1680 (C O), 1600 (C N), 1530 (Ar C C), 1300 (CH3),
White amorphous solid; yield: 85%; M.P: 177ꢀC; HRMS:
[M]•+ 529.1809 (Calcd. for C25H31N5O4S2; 529.1817); IR
(KBr, wave number, cm−1): 3341 (N–H), 2820 (Ar C–H),
1690 (C O), 1610 (C N), 1500 (Ar C C), 1350 (CH3),
1300 (S O), 1250 (C–O–C), 630 (C–H); 1H-NMR (CDCl3,
600 MHz, δ [ppm]): 9.91 (s, 1H, NH), 7.75 (d, J = 8.8 Hz,
2H, H-20, H-60), 7.46 (d, J = 8.4 Hz, 2H, H-200, H-600), 7.10
(d, J = 8.2 Hz, 2H, H-300, H-500), 7.03 (d, J = 8.8 Hz, 2H,
H-30, H-50), 4.66 (q, J = 7.2 Hz, 1H, H-3000), 3.90 (s, 3H, H-
1000), 3.85-3.81 (m, 2H, He-2, He-6), 3.42 (s, 3H, H-2000),
2.64-2.60 (m, 1H, H-4), 2.58-2.55 (m, 2H, Ha-2, Ha-6), 2.31
1
1250 (S O), 1150 (C–O–C), 710 (C–H); H-NMR (CDCl3,
600 MHz, δ [ppm]): 9.48 (s, 1H, NH), 7.95 (d, J = 8.0 Hz,
1H, H-600), 7.73 (d, J = 8.8 Hz, 2H, H-20, H-60), 7.18-7.14
(m, 2H, H-400, H-500), 7.05-7.02 (m, 3H, H-30, H-50, H-300),
4.60 (q, J = 7.2 Hz, 1H, H-3000), 3.90 (s, 3H, H-1000), 3.83-3.81
(m, 1H, He-2), 3.74-3.72 (m, 1H, He-6), 3.42 (s, 3H, H-2000),
2.67-2.64 (m, 1H, H-4), 2.63-2.57 (m, 2H, Ha-2, Ha-6), 2.22

14
VIRK ET AL.
(s, 3H, H-5000), 2.10-1.98 (m, 4H, He-3, He-5, Ha-3, Ha-5),
1.65 (d, J = 7.2 Hz, 3H, H-4000); 13C-NMR (CDCl3,
600 MHz, δ [ppm]): 168.87 (C-40), 163.08 (C-50000), 157.43
(C-30000), 151.59 (C-60000), 135.77 (C-100), 133.61 (C-400),
129.82 (C-20, C-60), 129.31 (C-200, C-600), 127.78 (C-10),
119.60 (C-300,C-500), 114.27 (C-30, C-50), 55.64 (C-1000), 45.55
(C-2, C-6), 44.26 (C-3000), 32.10 (C-4), 30.11 (C-2000), 29.08
(C-3, C-5), 20.84 (C-5000), 16.42 (C-4000).
(s, 3H, H-2000), 2.63-2.61 (m, 1H, H-4), 2.59-2.54 (m, 2H,
Ha-2, Ha-6), 2.12-2.07 (m, 2H, He-3, He-5), 2.02-1.88 (m,
2H, Ha-3, Ha-5), 1.66 (d, J = 7.2 Hz, 3H, H-400‘); 13C-NMR
(CDCl3, 150 MHz, δ [ppm]): 169.08 (C-40), 163.06 (C-50000),
157.37 (C-30000), 150.50 (C-60000), 141.13 (C-2000), 145.00 (C-
100), 129.82 (C-20, C-60), 127.90 (C-10), 123.92 (C-300),
120.74 (C-600), 119.75 (C-400), 114.27 (C-30, C-50), 110.12
(C-500), 55.62 (C-1000), 45.45 (C-2, C-6), 44.65 (C-3000), 31.89
(C-4), 29.98 (C-2000), 29.00 (C-3, C-5), 16.71 (C-4000).
3.5.14 | N-(2-Ethylphenyl)-
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9m)
3.5.16 | N-(4-Ethoxyphenyl)-
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9o)
Off white amorphous solid; yield: 90%; M.P: 185.7ꢀC;
HRMS: [M]•+ 543.1959 (Calcd. for C26H33N5O4S2;
543.1974); IR (KBr, wave number, cm−1): 3340 (N–H),
2800 (Ar C–H), 1670 (C O), 1600 (C N), 1570
(Ar C C), 1360 (CH3), 1200 (S O), 1150 (C–O–C),
Chocolate brown amorphous solid; yield: 90%; M.P:
178.5ꢀC; HRMS: [M]•+ 559.1917 (Calcd. for C26H33N5O5S2;
559.1923); IR (KBr, wave number, cm−1): 3341 (N–H),
2800 (Ar C–H), 1630 (C O), 1600 (C N), 1510 (Ar C C),
1
1
745 (C–H); H-NMR (CDCl3, 600 MHz, δ [ppm]): 9.44 (s,
1300 (S O), 1230 (C–O–C), 760 (C-H); H-NMR (CDCl3,
1H, NH), 7.73 (d, J = 8.7 Hz, 2H, H-20, H-60), 7.17 (d,
J = 7.4 Hz, 1H, H-600), 7.10-7.07 (m, 3H, H-300, H-400, H-
500), 7.01 (d, J = 8.7 Hz, 2H, H-30, H-50), 4.58 (q,
J = 7.2 Hz, 1H, H-3000), 3.89 (s, 3H, H-1000), 3.82-3.80 (m,
1H, He-2), 3.75-3.73 (m, 1H, He-6), 3.42 (s, 3H, H-2000),
2.66-2.65 (m, 1H, H-4), 2.64-2.51 (m, 2H, Ha-2, Ha-6), 2.09
(q, J = 6.5 Hz, 2H, H-5000), 2.02-1.89 (m, 4H, He-3, He-5,
Ha-3, Ha-5), 1.66 (d, J = 7.2 Hz, 3H, H-4000), 1.08 (t,
J = 7.5 Hz, 3H, H-6000); 13C-NMR (CDCl3, 150 MHz, δ
[ppm]): 169.62 (C-40), 163.07 (C-50000), 157.48 (C-30000),
151.56 (C-60000), 135.54 (C-100), 135.35 (C-200), 129.77 (C-20,
C-60), 128.62 (C-600), 127.81 (C-10), 126.26 (C-500), 125.20
(C-400), 123.31 (C-600), 114.27 (C-30, C-50), 55.62 (C-1000),
45.44 (C-2, C-6), 43.80 (C-3000), 31.82 (C-4), 30.03 (C-2000),
29.12 (C-3, C-5), 24.39 (C-5000), 16.69 (C-4000), 14.16 (C-6000).
600 MHz, δ [ppm]): 9.88 (s, 1H, NH), 7.72 (d, J = 8.8 Hz,
2H, H-20, H-60), 7.47 (d, J = 9.0 Hz, 2H, H-200, H-600), 7.02
(d, J = 8.8 Hz, 2H, H-30, H-50), 6.82 (d, J = 9.0 Hz, 2H, H-
300, H-500), 4.44 (q, J = 7.2 Hz, 1H, H-3000), 4.00 (q,
J = 6.9 Hz, 2H, H-5000), 3.89 (s, 3H, H-1000), 3.84-3.80 (m,
2H, He-2, He-6), 3.42 (s, 3H, H-2000), 2.63-2.56 (m, 1H, H-4),
2.54-2.51 (m, 2H, Ha-2, Ha-6), 2.09-1.94 (m, 4H, He-3, He-5,
Ha-3, Ha-5), 1.64 (d, J = 7.2 Hz, 3H, H-4000), 1.40 (t,
J = 6.9 Hz, 3H, H-6000); 13C-NMR (CDCl3, 150 MHz, δ
[ppm]): 168.75 (C-40), 163.07 (C-50000), 157.45 (C-30000),
155.51 (C-400), 151.47 (C-60000), 131.47 (C-100), 129.79 (C-20,
C-60), 127.72 (C-10), 121.12 (C-300,C-500), 114.71 (C-200, C-600),
114.28 (C-30, C-50), 63.72 (C-500‘), 55.63 (C-100‘), 45.56 (C-2,
C-6), 44.44 (C-300‘), 32.10 (C-4), 31.30 (C-200‘), 29.08 (C-3, C-
5), 16.55 (C-400‘), 14.75 (C-600‘).
3.5.15 | N-(2-Methoxyphenyl)-
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9n)
3.5.17 | 2-[(5-{1-[(4-Methoxyphenyl)
sulfonyl]-4-piperidinyl}-4-methyl-4H-
1,2,4-triazol-3-yl)sulfanyl]-N-
phenylpropanamide (9p)
Off white amorphous solid; yield: 88%; M.P: 168.5ꢀC;
HRMS: [M]•+ 545.1758 (Calcd. for C26H33N5O5S2;
545.1767); IR (KBr, wave number, cm−1): 3341 (N–H),
2800 (Ar C–H), 1650 (C O), 1600 (C N), 1500 (Ar C C),
White amorphous solid; yield: 89%; M.P: 180.0ꢀC; HRMS:
[M]•+ 515.1653 (Calcd. for C24H29N5O4S2; 515.1661); IR
(KBr, wave number, cm−1): 3337 (N–H), 2800 (Ar C–H),
1650 (C O), 1600 (C N), 1550 (Ar C C), 1300 (CH3), 1250
(S O), 1150 (C–O–C), 700 (C–H); 1H-NMR (CDCl3,
600 MHz, δ [ppm]): 10.08 (s, 1H, NH), 7.73 (d, J = 8.8 Hz,
2H, H-20, H-60), 7.58 (d, J = 7.6 Hz, 2H, H-200, H-600), 7.29 (t,
J = 7.6 Hz, 2H, H-300, H-500), 7.08 (t, J = 7.3 Hz, 1H, H-400),
7.02 (d, J = 8.8 Hz, 2H, H-30, H-50), 4.47 (q, J = 7.2 Hz, 1H,
H-3000), 3.90 (s, 3H, H-1000), 3.85-3.80 (m, 2H, He-2, He-6), 3.43
1
1350 (CH3), 1250 (S O), 1150 (C–O–C), 700 (C–H); H-
NMR (CDCl3, 600 MHz, δ [ppm]): 9.40 (s, 1H, NH), 7.73
(d, J = 8.9 Hz, 2H, H-20, H-60), 7.02 (d, J = 8.8 Hz, 2H, H-
30, H-50), 6.93-6.91 (m, 2H, H-500, H-600), 7.84-6.83 (m, 2H,
H-300, H-400), 4.60 (q, J = 7.1 Hz, 1H, H-3000), 3.90 (s, 3H, H-
1000), 3.83 (s, 3H, H-5000), 3.81-3.75 (m, 2H, He-2, He-6), 3.41

VIRK ET AL.
15
(s, 3H, H-2000), 2.63-2.60 (m, 1H, H-4), 2.57-2.51 (m, 2H, Ha-
2, Ha-6), 2.10-2.00 (m, 4H, He-3, He-5, Ha-3, Ha-5), 1.66 (d,
J = 7.2 Hz, 3H, H-4000); 13C-NMR (CDCl3, 150 MHz, δ
[ppm]): 169.09 (C-40), 163.09 (C-50000), 157.49 (C-30000), 151.54
(C-60000), 138.34 (C-100), 129.78 (C-20, C-60), 128.84 (C-200, C-
600), 127.79 (C-10), 124.04 (C-400), 119.83 (C-300, C-500), 114.28
(C-30, C-50), 55.64 (C-1000), 45.54 (C-2, C-6), 44.36 (C-3000),
32.15 (C-4), 30.13 (C-2000), 27.95 (C-3, C-5), 16.43 (C-4000).
1.57 (d, J = 7.2 Hz, 3H, H-4000), 1.35-1.27 (m, 4H, H-200, H-
600), 1.22-1.15 (m, 4H, H-300, H-500), 1.07-1.05 (m, 2H, H-
13
400); C-NMR (CDCl3, 150 MHz, δ [ppm]): 170.01 (C-40),
163.17 (C-5000), 157.20 (C-300), 152.66 (C-6000), 129.82 (C-20,
C-600), 127.88 (C-10), 114.27 (C-30, C-50), 55.63 (C-1000),
48.38 (C-100), 45.52 (C-2, C-6), 44.47 (C-3000), 32.60 (C-200,
C-600), 32.14 (C-300, C-500), 31.23 (C-4), 30.11 (C-2000), 29.09
(C-3, C-5), 25.46 (C-400), 16.91 (C-4000).
3.5.18 | N-Benzyl-
3.5.20 | Acetyl cholinesterase inhibition
assay
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9q)
The potential of synthesized array of 1,2,4-triazole hybrids
was checked against the acetyl cholinesterase by following
the reported Ellman's procedure with necessary modifica-
tions.[4] The basic for the reported method is development
of yellow TNB by DTNB along with thiocholine. The refer-
ence inhibitor that was utilized to access the potential of
synthesized compounds, 9a-r, was Eserine. The assay
could be well justified by the given below equation.
Lemon yellow sticky solid; yield: 87%; M.P: 170.5ꢀC;
HRMS: [M]•+ 529.1809 (Calcd. for C25H31N5O4S2;
529.1817); IR (KBr, wave number, cm−1): 3340 (N–H),
2800 (Ar C–H), 1650 (C O), 1600 (C N), 1450
(Ar C C), 1350 (CH3), 1200 (S O), 1150 (C–O–C),
730 (C-H); 1H-NMR (CDCl3, 600 MHz, δ [ppm]): 12.65 (s,
1H, NH), 8.57 (d, J = 8.2 Hz, 2H, H-200, H-600), 8.10-8.07
(m, 1H, H-400), 7.66 (d, J = 8.7 Hz, 2H, H-20, H-60),
7.005-7.02 (m, 2H, H-300, H-500), 7.00 (d, J = 8.8 Hz, 2H, H-
3 , H-50), 4.18 (q, J = 6.6 Hz, 1H, H-3000), 3.88 (s, 3H, H-
1000), 3.80-3.78 (m, 1H, He-2), 3.74-3.71 (m, 1H, He-6), 3.34
(s, 3H, H-2000), 2.97 (s, 2H, H-5000), 2.57-2.54 (m, 1H, H-4),
2.50-2.46 (m, 2H, Ha-2, Ha-6), 2.27-2.16 (m, 2H, He-3, He-
5), 2.03-1.92 (m, 2H, Ha-3, Ha-5), 1.65 (d, J = 6.9 Hz, 3H,
H-4000); 13C-NMR (CDCl3, 150 MHz, δ [ppm]): 169.07 (C-
40), 163.08 (C-50000), 158.09 (C-30000), 154.02 (C-60000), 148.86
(C-100), 140.21 (C-200, C-600), 129.74 (C-20, C-60), 127.58 (C-
10), 122.74 (C-300, C-500), 118.98 (C-400), 114.26 (C-30, C-50),
55.63 (C-1000), 45.79 (C-2, C-6), 45.43 (C-3000), 35.07 (C-5000),
32.47 (C-2000), 31.45 (C-4), 28.54 (C-3, C-5), 16.83 (C-4000).
AChE
Thiocholine + acetic acid
Acetylcholine + H2O
Formation of TNB
[Yellow Color, 410 nm]
Thiocholine + DTNB
Each well in the 96-well plate was filled with 60 μL
buffer solution of pH 7.7 followed by the addition of syn-
thesized compounds 10 μL. The whole mixture was
scanned at 405 nm by maintaining the temperature at
37ꢀC. By the addition of acetylthiocholine (10 μL) followed
by the addition of 10 μL DTNB (0.5 mM), the reaction was
started. At 37ꢀC for 16 to 30 minutes, the mixture was
incubated, and absorbance was noted at 405 nm by using
96-well plate reader Synergy HT, Biotek, USA. The whole
experiment was performed in triplicate and % inhibition
was measured by following the given formula.
3.5.19 | N-Cyclohexyl-
2-[(5-{1-[(4-methoxyphenyl)sulfonyl]-
4-piperidinyl}-4-methyl-4H-1,2,4-triazol-
3-yl)sulfanyl]propanamide (9r)
Control is the absorbance without test sample while
test is in the presence of sample. By using Ez-Fit software
(Perrella Scientific Inc. Amherst, Massachusetts), the
IC50 values were calculated.
Brown amorphous solid; yield: 88%; M.P: 173.0ꢀC;
HRMS: [M]•+ 521.2122 (Calcd. for C24H35N5O4S2;
521.2130); IR (KBr, wave number, cm−1): 3340 (N–H),
2800 (Ar C–H), 1650 (C O), 1600 (C N), 1520
(Ar C C), 1350 (CH3), 1250 (S O), 1100 (C–O–C),
700 (C–H); 1H-NMR (CDCl3, 600 MHz, δ [ppm]): 7.73 (d,
J = 8.8 Hz, 2H, H-20, H-60), 7.02 (d, J = 8.8 Hz, 2H, H-30,
H-50), 4.22 (q, J = 7.2 Hz, 1H, H-3000), 3.90 (s, 3H, H-1000),
3.84-3.82 (m, 2H, He-2, He-6), 3.69-3.67 (m, 1H, H-100),
3.44 (s, 3H, H-20000), 2.68-2.65 (m, 1H, H-4), 2.63-2.56 (m,
2H, Ha-2, Ha-6), 2.11-2.00 (m, 4H, He-3, He-5, Ha-3, Ha-5),
3.5.21 | α-Glucosidase inhibition assay
The α-glucosidase inhibition potential was calculated by
following the reported procedure with necessary modifi-
cations.[12] A mixture of 70 μL phosphate buffer saline of
pH 6.8, 10 μL of enzyme and test sample each was taken
in 96-well plate. The whole mixture was incubated at

16
VIRK ET AL.
37ꢀC for 10 minutes, and absorbance was calculated at
400 nm. After incubation, 10 μL p-nitrophenyl glu-
copyranoside (0.5 mM) was added as a substrate. The
absorbance after incubation period was again calculated
at 400 nm with the aid of Synergy HT microplate reader.
The whole experiment was carried out in triplicate. The
% inhibition and IC50 values were calculated in the simi-
lar way as described for cholinesterase enzymes.
The synthesized compounds were structurally elaborated
through 1H-NMR, 13C-NMR, and IR techniques. This
potential was further elaborated through molecular dock-
ing study. The BSA binding study revealed the excellent
binding potential of the synthesized compounds.
ORCID
Aziz-ur- Rehman https://orcid.org/0000-0002-0262-
7726
3.5.22 | Statistical analysis
REFERENCES
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3.5.23 | Computational studies
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The interaction of synthesized compounds with AChE
active site was determined by using the RCSB data bank for
protein in order to collect co-crystal 3D structure.[5] SYBYL-
X 1.3 was used for structure preparation of all the available
proteins, while for the types of atoms, charges, and missing
hydrogen atoms, an AMBER 7 FF99 force field was uti-
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3D-structures of active inhibitors with consideration of
using Tripo force field with Gasteigere Hückel atomic
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3.5.24 | BSA binding interactions using
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fluorescence measurements
The BSA binding studies were carried out to find out the
inter action of synthesized series of compounds with pro-
tein. The flurometric titrations were used to calculate the
quenching constant. A mixture of test compound along
with buffer and BSA solution was mixed. The mixture
was excited at 295 nm. The intensity of synthesized com-
pounds alone and with test compound was measured at
336 nm. The site selective binding was measured with
and in absence of site markers (ibuprofen or warfarin).[1]
How to cite this article: Virk NA, Rehman A,
Abbasi MA, et al. Microwave-assisted synthesis of
triazole derivatives conjugated with piperidine as
new anti-enzymatic agents. J Heterocycl Chem.
2019;1–16. https://doi.org/10.1002/jhet.3875
4 | CONCLUSION
The current study was performed to synthesize the com-
pounds bearing heterocyclic moieties together in one unit
and then to evaluate their enzyme inhibition potential.