Green synthesis and antibacterial evaluation of some new 1-aryl-3-(1-aryl-1H-[1,2,3]triazol-4-yl)-propenones

Article abstract of DOI:10.1134/S1070363216060293

A new series of 1-aryl-3-(1-aryl-1H-[1,2,3]triazol-4-yl)propenones (6a–6j) was synthesized by condensation of substituted acetophenones (5a–5c) with substituted 1-aryl-1H-[1,2,3]triazole-4-carbaldehydes (4a–4d) in the presence of potassium hydroxide under

Full text of DOI:10.1134/S1070363216060293

ISSN 1070-3632, Russian Journal of General Chemistry, 2016, Vol. 86, No. 6, pp. 1419–1423. © Pleiades Publishing, Ltd., 2016.
Green Synthesis and Antibacterial Evaluation of Some New
1-Aryl-3-(1-aryl-1H-[1,2,3]triazol-4-yl)-propenones1
G. Linga Goud, S. Ramesh, D. Ashok, and V. Prabhakar Reddy
Green and Medicinal Chemistry Lab, Department of Chemistry, Osmania University, Hyderabad, 500007 India
e-mail: lingamgudikadi@gmail.com
Received November 30, 2015
Abstract—A new series of 1-aryl-3-(1-aryl-1H-[1,2,3]triazol-4-yl)propenones (6a–6j) was synthesized by
condensation of substituted acetophenones (5a–5c) with substituted 1-aryl-1H-[1,2,3]triazole-4-carbaldehydes
(4a–4d) in the presence of potassium hydroxide under conditions of grinding and microwave irradiation. All
the newly synthesized compounds were characterized by the IR, NMR, and mass spectroscopic analyses and
their antibacterial activity against gram-positive and gram-negative bacterial strains was evaluated. Among the
compounds synthesized, better activity was exhibited by 6a, 6c, 6f, 6g, and 6i.
Keywords: triazole aldehyde, triazole chalcone, antibacterial activity
DOI: 10.1134/S1070363216060293
with chemical processes and products by inventing
novel reactions that can maximize the desired products
and minimize by-products, by designing new synthetic
schemes and apparatus that can simplify a chemical
technology, and by searching for environmentally
friendly solvents. In continuation of our previous study
on the solvent-free organic synthesis [14], we report
here a simple, efficient, and solvent-free synthesis of
chalcones, including grinding and microwave irradia-
tion. The title compounds, 1-aryl-3-(1-aryl-1H-[1,2,3]-
triazol-4-yl)propenones (6a–6j), were synthesized by
the reaction of substituted aceto-phenones 5a–5c with
1-aryl-1H-[1,2,3]triazole-4-carbaldehydes (4a–4d) in
the presence of potassium hydroxide under conditions
of grinding and microwave irradiation.
INTRODUCTION
Chalcones are a part of selected group of chemical
compounds with diverse pharmacological activities.
The term chalconoid has been used for the whole
family of compounds bearing the 1,3-diarylpropane
skeleton, which can be functionalized in the propane
chain by the olefinic, keto, and/or hydroxyl groups.
Chalcones bearing the 1,3-diaryl-2-propen-1-one
carbon framework are the most common and wide-
spread compounds of the chalconoid group [1, 2].
Chalcones are potential compounds owing to their
antimalarial [3–6] and anti-tuberculosis [7] activities.
The antimictrobial properties of heterocyclic deriva-
tives have been reported in a number of publications
[8–11]. Chalcones and their derivatives are poly-
phenolic compounds of the flavonoids family. They
are present in many plants as metabolic precursors of
other flavonoids and isoflavonoids [13]. From the
viewpoint of synthesis, there is a great interest for the
development of structural analogues of chalcones. The
Claisen–Schmidt condensation of acetophenone
derivatives with benzaldehyde derivatives in the
presence of both acid and base catalysts has been by
far the leading reaction employed for these compounds.
RESULTS AND DISCUSSION
The synthetic route adopted for the title compounds
is illustrated in Schemes 1 and 2. First, aromatic azides
(2a–2d) were synthesized by diazotization [15] of
corresponding anilines 1a–1d and then, (1-phenyl-1H-
1,2,3-triazol-4-yl)methanol (3a–3d) was obtained
through Huisgen 1,3-dipolar cycloaddition [16]
between an azide and propargyl alcohol. The 4-
carboxaldehyde-1,2,3-triazoles (4a–4d) were prepared
by oxidation of the intermediates (3a–3d) in the
presence of 2-iodoxy-benzoic acid (IBX) [17].
On the other hand, Green chemistry for chemical
synthesis addresses our future challenges in working
The new 1,2,3-triazolo chalcone derivatives (6a–6j)
were synthesized by reacting 1-aryl-1H-[1,2,3]triazole-
1 The text was submitted by the authors in English.
1419

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G. LINGA GOUD et al.
Scheme 1. Synthesis of 1-aryl-1H-[1,2,3]triazole-4-carbaldehydes (4a–4d).
R1
R1
NH2
N3
3
2
1
N
N
O
N
OH
N
R1
1a−1d
R1
2a−2d
N
N
H
3a−3d
4a−4d
R1 = H, 2-OMe, 2-Cl, 4-Cl. Reagents and conditions: (1) NaNO2, HCl 10%; NaN3, reaction time 2–4 h; (2) propargyl alcohol,
CuSO4·5H2O, sodium ascorbate, H2O : DMF (1 : 2), reaction time 3 h; (3) IBX/DMSO, reaction time3 h.
Scheme 2. Synthesis of 1-aryl-3-(1-aryl-1H-[1,2,3]triazol-4-yl)-propenones (6a–6j).
R1
R1
R2
H
R2
KOH
N
N
N
MWI or grinding
O
N
N
O
N
O
4a−4d
5a−5c
6a−6j
6a: R1 = H, R2 = H, 6b: R1 = 20OMe, R2 = H, 6c: R1 = 2-Cl, R2 = H, 6d: R1 = 4-Cl, R2 = H, 6e: R1 = H, R2 = 4-Me, 6f: R1 =
2-OMe, R2 = 4-Me, 6g: R1 = 2-Cl, R2 = 4-Me, 6h: R1 = 4-Cl, R2 = 4-Me, 6i: R1 = H, R2 = 4-Br, 6j: R1 = 2-OMe, R2 = 4-Br.
Reaction time 3 h.
4-carbaldehyde (4a–4d) with the substituted aceto-
phenones (5a–5c) in the presence of potassium hyd-
roxide under conditions of grinding and microwave
irradiation. The synthesis of title compounds under
microwave irradiation gave excellent yields in short
reaction time. The newly synthesized compounds were
characterized by the NMR and mass spectrometric
The zone of inhibition (in mm) was compared with
that of the standard drug Ampicillinum. The
compounds 6a, 6c, 6f, 6g, and 6i are more potent than
the standard drug.
EXPERIMENTAL
1
Melting points were determined in an open glass
capillary tube on a Gallenkamp MFB-595 apparatus
and are given uncorrected. IR spectra of samples (KBr
tablets) were recorded on a Perkin-Elmer FT-IR-8400s
analyses. The H NMR spectrum of compound 6j
contains a characteristic doublet of the Cα–H proton at
δ = 7.08–7.11 (J = 14.8 Hz) and a singlet of the
triazole proton at δ = 8.28. In the 13C NMR spectrum,
peak due to the carbonyl carbon is present at 190.1 ppm.
The LCMS spectrum has [M + 2]+ peak at m/z 385.
Thus, on the basis of the above studies 6j was identified
1
spectrometer. H NMR (400 MHz) and 13C NMR
(100 MHz) spectra were measured on a Bruker Avance
II 400 spectrometer with CDCl3, DMSO as solvent and
TMS as internal standard; chemical shifts are given in
ppm. Mass spectra were measured on a SHIMADZU
LCMS 2020 mass spectrometer. The progress of
reactions was monitored by thin layer chromatography
(Silica Gel 60 F254 Aluminum Sheet, Merck).
Elemental analysis was done on a Perkin Elmer CHN-
2400 analyzer. Microwave reactions were carried out
in a Milestone multiSYNTH microwave system.
as
1-(4-bromo-phenyl)-3-[1-(2-methoxy-phenyl)-1H-
[1,2,3]triazol-4-yl]propenone.
Antibacterial activity. All the synthesized
compounds were screened in vitro for their anti-
bacterial activity against two gram +ve bacterial
strains, Staphylococcus aureus (ATCC-9144) and
Bacillus cereus (ATCC-11778), and two gram –ve
bacterial strains, Escherichia coli (ATCC-8739) and
Proteus vulgaris (ATCC-29213). The antibacterial
activity was evaluated by cup-plate agar diffusion
method at the concentrations 25, 50, and 100 µg/mL.
General procedure for synthesis of 1-aryl-3-(1-
aryl-1H-[1,2,3]triazol-4-yl)propenones
(6a–6j).
a. Microwave method. A mixture of 1-aryl-1H-[1,2,3]-
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GREEN SYNTHESIS AND ANTIBACTERIAL EVALUATION
1421
The yield for compounds 6a–6j synthesized under different
conditions
triazole-4-carbaldehydes (4a–4d) (0.01 mol) and
substituted acetophenones (5a–5c) (0.01 mol) in a
powdered potassium hydroxide (0.02 mol) was
subjected to microwave irradiation at 180 W for 1–
2 min (see the table). The reaction progress was
monitored by TLC. After the reaction was complete,
the reaction mixture was poured into water and a dilute
HCl was added to it to neutral pH. The solid
precipitate was filtered, washed with water, dried, and
recrystallized from ethanol to give 1-aryl-3-(1-aryl-
1H-[1,2,3]triazol-4-yl)propenones (6a–6j).
Grinding method
Microwave method
Product
time, min
yield, % time, min yield, %
6
5
8
6
7
9
5
8
7
6
85
80
81
80
85
82
80
83
85
84
1.0
1.0
1.5
1.0
1.5
2.0
1.0
2.0
1.5
1.0
95
92
90
95
94
92
94
95
95
92
6a
6b
6c
6d
6e
6f
b. Grinding method. A mixture of 1-aryl-1H-[1,2,3]-
triazole-4-carbaldehydes (4a–4d) (0.01 mol) and sub-
stituted acetophenones (5a–5c) (0.01 mol) in a
powdered potassium hydroxide (0.02 mol) was
inserted into a mortar and ground for 5–9 min (see the
table). Progress of the reaction was monitored by TLC.
After completing the reaction, crushed ice was
introduced and a dilute HCl was added to neutral pH.
The solid precipitate was separated by filtration and
recrystal-lized from ethanol to give 1-aryl-3-(1-aryl-
1H-[1,2,3]-triazol-4-yl)propenones (6a–6j).
6g
6h
6i
6j
triazole H), 7.98–8.06 m (3H, Ar-H, Hβ), 7.72–7.80 m
(5H, Ar-H), 7.20–7.27 d (1H, J = 14.6 Hz, Hα), 7.12–
7.16 m (2H, Ar-H). 13C NMR spectrum (CDCl3,
DMSO, 100 MHz), δ, ppm: 190.0, 161.2, 147.1, 140.5,
135.9, 132.5, 129.3 127.8, 126.7, 125.7, 122.8, 122.6,
121.8; M 310 [M + H]+. Found, %: C 65.57; H 3.78; N
13.28. C17H12ClN3O. Calculated, %: C 65.92; H 3.90;
N 13.57.
1-Phenyl-3-(1-phenyl-1H-[1,2,3]triazol-4-yl)-
propenone (6a). Yield 92%, mp 178–180°C. IR spec-
1
trum (KBr), ν, cm–1: 1630 (C=O). H NMR spectrum
(CDCl3, 400 MHz), δ, ppm: 8.25 s (1H, triazole H),
7.92–8.00 m (3H, Ar-H, Hβ), 7.72–7.86 m (5H, Ar-H),
7.29–7.30 d (1H, J = 15.2 Hz, Hα), 7.14–7.19 m (3H,
Ar-H). 13C NMR spectrum (DMSO, 100 MHz), δ,
ppm: 189.0, 160.9, 147.2, 140.2, 136.8, 132.1, 129.2,
127.6, 126.7, 125.7, 122.8, 121.9; M 276 [M + H]+.
Found, %: C 73.59; H 4.24; N 14.40. C17H13N3O.
Calculated, %: C 74.17; H 4.76; N 15.26.
3-[1-(4-Chlorophenyl)-1H-[1,2,3]triazol-4-yl]-1-
phenyl-propenone (6d). Yield 92%, mp 200–202°C.
1
IR spectrum (KBr), ν, cm–1: 1630 (C=O). H NMR
spectrum (CDCl3, 400 MHz), δ, ppm: 8.17 s (1H,
triazole H), 7.95–8.02 m (4H, Ar-H, Hβ), 7.69–7.75 m
(4H, Ar-H), 7.22–7.28 d (1H, J = 14.9 Hz, Hα), 7.10–
7.18 m (2H, Ar-H). 13C NMR spectrum (CDCl3, 100 MHz),
δ, ppm: 190.2, 161.0, 147.5, 140.2, 135.8, 132.7, 129.3
127.8, 126.5, 125.9, 122.8, 122.6, 121.5; M 310 [M +
H]+. Found, %: C 65.50; H 3.72; N 13.26.
C17H12ClN3O. Calculated, %: C 65.92; H 3.90; N 13.57.
3-[1-(2-Methoxyphenyl)-1H-[1,2,3]triazol-4-yl]-1-
phenyl-propenone (6b). Yield 92%, mp 190–192°C.
1
IR spectrum (KBr), ν, cm–1: 1636 (C=O). H NMR
spectrum (CDCl3, 400 MHz), δ, ppm: 8.51 s (1H,
triazole H), 8.13–8.16 m (6H, Ar-H, Hβ), 7.85–7.88 m
(1H, Ar-H), 7.45–7.49 d (1H, J = 14.9 Hz, Hα), 7.15–
7.18 m (3H, Ar-H), 3.95 s (3H, O-CH3). 13C NMR
spectrum (CDCl3, 100 MHz), δ, ppm: 190.1, 161.2,
147.5, 140.4, 135.9, 132.1, 129.2 127.8, 126.7, 125.6,
122.8, 122.5, 121.9, 55.6; M 306 [M + H]+. Found, %:
C 69.93; H 4.69; N 12.89. C18H15N3O2. Calculated, %:
C 70.81; H 4.95; N 13.76.
3-(1-Phenyl-1H-[1,2,3]triazol-4-yl)-1-p-tolyl-pro-
penone (6e). Yield 92%, mp 168–170°C. IR spectrum
(KBr), ν, cm–1: 1634 (C=O). 1H NMR spectrum (CDCl3,
400 MHz), δ, ppm: 8.28 s (1H, triazole H), 7.98–8.05
m (3H, Ar-H, Hβ), 7.81–7.85 m (3H, Ar-H), 7.40–7.48
m (2H, Ar-H), 7.28–7.33 d (1H, J = 15.2 Hz, Hα),
7.10–7.16 m (2H, Ar-H), 2.40 s (3H, Ar-CH3). 13C
NMR spectrum (CDCl3, 100 MHz), δ, ppm: 190.1,
161.6, 147.0, 140.4, 137.0, 131.5, 129.1, 127.6, 126.7,
125.7, 122.9, 120.2, 22.5; M 290 [M + H]+. Found, %:
3-[1-(2-Chlorophenyl)-1H-[1,2,3]triazol-4-yl]-1-
phenyl-propenone (6c). Yield 95%, mp 196–198°C.
1
IR spectrum (KBr), ν, cm–1: 1634 (C=O). H NMR
spectrum (DMSO, 400 MHz), δ, ppm: 8.20 s (1H,
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G. LINGA GOUD et al.
C 74.50; H 5.02; N 14.26. C18H15N3O. Calculated, %:
C 74.72; H 5.23; N 14.52.
57.49; H 3.27; N 11.70. C17H12BrN3O. Calculated, %:
C 57.65; H 3.41; N 11.86.
3-[1-(2-Methoxyphenyl)-1H-[1,2,3]triazol-4-yl]-1-
p-tolyl-propenone (6f). Yield 90%, mp 160–162°C.
1-(4-Bromophenyl)-3-[1-(2-methoxy-phenyl)-1H-
[1,2,3]triazol-4-yl]propenone (6j). Yield 90%, mp
178–180°C. IR spectrum (KBr), ν, cm–1: 1632 (C=O).
1H NMR spectrum (CDCl3, 400 MHz), δ, ppm: 8.28 s
(1H, triazole H), 7.85–7.89 m (3H, Ar-H, Hβ), 7.65–
7.71 m (2H, Ar-H), 7.40–7.46 m (2H, Ar-H), 7.08–
7.11 d (1H, J = 14.8 Hz, Hα), 6.95–6.99 m (2H, Ar-H),
3.90 s (3H, O–CH3). 13C NMR spectrum (CDCl3,
100 MHz), δ, ppm: 190.1, 160.4, 147.5, 140.2, 137.7,
131.5, 129.2, 127.6, 126.9, 125.7, 122.9, 121.7, 116.8,
56.1; M 385 [M + 2]+. Found, %: C 56.10; H 3.54; N
10.81. C18H14BrN3O2. Calculated, %: C 56.27; H 3.67;
N 10.94.
1
IR spectrum (KBr), ν, cm–1: 1635 (C=O). H NMR
spectrum (CDCl3, 400 MHz), δ, ppm: 8.31 s (1H,
triazole H), 7.97–8.02 m (3H, Ar-H, Hβ), 7.81–7.85 m
(2H, Ar-H), 7.43–7.48 m (1H, Ar-H), 7.30–7.32 d (2H,
J = 15.6 Hz, Hα), 7.10–7.15 m (2H, Ar-H), 3.93 s (3H,
O–CH3), 2.44 s (3H, Ar-CH3). 13C NMR spectrum
(CDCl3, 100 MHz), δ, ppm: 190.2, 161.5, 147.0, 140.5,
137.0, 131.1, 129.2, 127.7, 126.7, 125.7, 122.8, 121.9,
118.3, 116.8, 56.8, 22.7; M 320 [M + H]+. Found, %: C
70.20; H 4.91; N 11.88. C19H17N3O2. Calculated, %: C
71.46; H 5.37; N 13.16.
3-[1-(2-Chlorophenyl)-1H-[1,2,3]triazol-4-yl]-1-
p-tolyl-propenone (6g). Yield 93%, mp 195–197°C.
CONCLUSIONS
1
IR spectrum (KBr), ν, cm–1: 1635 (C=O). H NMR
In conclusion, a convenient, high-efficiency, and
environmentally friendly synthetic procedure, includ-
ing microwave irradiation, was developed for the
synthesis of various triazole chalcones (6a–6j) and the
antibacterial activity of the synthesized compounds
was evaluated. It was found that test compounds 6a,
6c, 6f, 6g, and 6i have better antibacterial activity
against gram-positive and gram-negative bacteria than
Ampicillinum. The above results suggest that triazole
chalcones, as antibacterial agents, have good potential
for further development. The results of this study may
be a helpful guide for medicinal chemists engaged in
this area.
spectrum (CDCl3, 400 MHz), δ, ppm: 8.26 s (1H,
triazole H), 7.96–8.02 m (3H, Ar-H, Hβ), 7.80–7.85 m
(4H, Ar-H), 7.26–7.31 d (1H, J = 15.6 Hz, Hα), 7.10–
7.15 m (2H, Ar-H), 2.44 s (3H, Ar-CH3). 13C NMR
spectrum (CDCl3, 100 MHz), δ, ppm: 190.0, 161.5,
147.2, 140.6, 137.6, 131.1, 129.2, 127.6, 126.8, 125.5,
122.9, 121.7, 116.8, 22.5; M 324 [M + H]+. Found, %:
C 66.77; H 4.18; N 12.62. C18H14ClN3O. Calculated,
%: C 66.77; H 4.36; N 12.98.
3-[1-(4-Chlorophenyl)-1H-[1,2,3]triazol-4-yl]-1-
p-tolyl-propenone (6h). Yield 90%, mp 188–190°C.
1
IR spectrum (KBr), ν, cm–1: 1630 (C=O). H NMR
spectrum (CDCl3, 400 MHz), δ, ppm: 8.21 s (1H,
triazole H), 7.95–8.02 m (4H, Ar-H, Hβ), 7.81–7.86 m
(3H, Ar-H), 7.26–7.31 d (1H, J = 15.6 Hz, Hα), 7.10–
7.14 m (2H, Ar-H), 2.42 s (3H, Ar-CH3). 13C NMR
spectrum (CDCl3, 100 MHz), δ, ppm: 190.0, 161.6,
147.2, 140.5, 137.7, 131.2, 129.2, 127.5, 126.9, 125.5,
122.7, 121.7, 22.5; M 324 [M + H]+. Found, %: C
66.70; H 4.19; N 12.59. C18H14ClN3O. Calculated, %:
C 66.77; H 4.36; N 12.98.
ACKNOWLEDGMENTS
The authors are grateful to the Head of the
Department of Chemistry and Director of the Central
Facilities for the Research and Development (CFRD)
at the Osmania University in Hyderabad for providing
laboratory equipment. G.L. Goud is also grateful to the
Junior Research Fellowship for financial support.
1-(4-Bromophenyl)-3-(1-phenyl-1H-[1,2,3]triazol-
4-yl)propenone (6i). Yield 95%, mp 164–167°C. IR
spectrum (KBr), ν, cm–1: 1635 (C=O). 1H NMR
spectrum (CDCl3, 400 MHz), δ, ppm: 8.26 s (1H,
triazole H), 7.96–8.02 m (3H, Ar-H, Hβ), 7.80–7.85 m
(3H, Ar-H), 7.26–7.31 t (2H, Ar-H), 7.10–7.15 m (2H,
Ar-H), 6.05 d (1H, J = 15.1 Hz, Hα). 13C NMR
spectrum (CDCl3, 100 MHz), δ, ppm: 190.0, 161.6,
147.1, 140.7, 137.7, 131.3, 129.1, 127.6, 126.8, 125.5,
122.9, 121.7, 116.8; M 355 [M + 2]+. Found, %: C
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