Microwave induced improved synthesis of some novel substituted 1, 3-diarylpropenones and their antimicrobial activity

Article abstract of DOI:10.1155/2011/165047

Application of solid support, solvent free reaction condition and a dynamic microwave power system in the chemical synthesis of some novel 1, 3-diaryl-propenones has been described. A series of chalcones (3a-h) were synthesized by the condensation of 4-hy

Full text of DOI:10.1155/2011/165047

ISSN: 0973-4945; CODEN ECJHAO
E-Journal of Chemistry
2011, 8(2), 665-670
http://www.e-journals.net
Microwave Induced Improved Synthesis of
Some Novel Substituted 1, 3-Diarylpropenones and
their Antimicrobial Activity
K. L. AMETA*, BIRESH KUMAR and NITU S. RATHORE
Department of Chemistry, FASC
Mody Institute of Technology & Science
(Deemed University) Lakshmangarh - 332311, Rajasthan, India
klameta77@yahoo.co.in
Received 31 August 2010; Accepted 24 November 2010
Abstract: Application of solid support, solvent free reaction condition and a
dynamic microwave power system in the chemical synthesis of some novel
1, 3-diaryl-propenones has been described. A series of chalcones (3a-h) were
synthesized by the condensation of 4-hydroxy-3,5-dinitroacetophenone with
various substituted aromatic aldehydes in presence of montmorrilonite K10 as a
catalyst and solid support media under microwave irradiation. The protocol
offers several advantages such as simple procedure, fast reaction rate, mild
reaction condition, eco-friendly and improved yield as compared to
conventional methods. These compounds have been screened for their
antibacterial and antifungal activities against different microorganisms. The
structures of novel synthesized compounds have been established on the basis
of elemental analysis, 1H NMR, 13C NMR and IR spectral data.
Keywords: Microwave irradiation, 1,3-Diarylpropenones, Acetophenone, Aromatic aldehydes,
Montmorrilonite K10.
Introduction
Due to the rapid development of bacterial resistant to anti bacterial agents, it is vital to
discover novel scaffold for the design and synthesis of the new antibacterial agents to help in
the battle against pathogenic microorganism. 1,3-Diarylpropenones (chalcones) represent an
essential group of natural as well as synthetic products and some of them possess wide range
of pharmacological activities such as antitumor1, antibacterial2, anticancer3, antitubercular4,
anti-inflammatory5, antioxidant6, antimalarial7 and antileshmanial8, etc. The presence of
reactive α, β-unsaturated keto group in the 1,3 diarylpropeneones is found to be responsible for
their biological activity. In addition, these compounds are of a great interest due to their use as
starting material in the synthesis of a series of a heterocyclic9, carbocyclic10 and flavonoids11.
Moreover these are important intermediates in many addition reactions of nucleophiles due to
inductive polarization of carbonyl group at the β-position. Several strategies for the synthesis
of the system based on the formation of carbon-carbon bond have been reported. Among
them the direct aldol condensation and Claisen Schmidt condensation still occurs prominent

666
K. L. AMETA et al.
position. The main method for the synthesis of chalcones is the classical Claisen-Schmidt
condensation in the presence of aqueous alkali12, Ba(OH)2,13 microwave irradiation14-17, ultra sound
irradiation18. However many of this methods suffered from harsh reaction conditions, toxic reagents,
strong acidic / basic conditions, prolonged reaction time, poor yield and low selectivity. Although,
several modification have been made to counter these problems. There is still a need for the
development of selective and better strategies for the synthesis of α, β-unsaturated carbonyl
compounds. Keeping in view of these finding and in continuation of our interest in the chemistry of
chalcones19-24 and usefulness of microwave in various organic synthesis25-27, herein we describe a
simple and convenient method for the synthesis of chalcones, using Montmorrilonite K10 clay under
microwave irradiation in solvent free environment, with improved yields and short reaction time.
Experimental
All melting points (m.ps.) were determined in open capillaries on Veego (VMP - PM) melting
point apparatus and are uncorrected. IFB 20S2 Microwave oven with ten power levels was
employed for the synthesis of these compounds. The purity of the compounds was routinely
checked by thin layer chromatography (TLC) with Silica Gel G (Merk). The instruments used for
spectroscopic data are; IR-FTTR spectrophotometer Perkin Elmer RX 1 (KBr), 1HNMR & 13C
NMR (CDCl3 – solvent) on 500 MHz FT-NMR spectrometer Bruker AV III and elemental
analysis was carried out on a Carlo Erba 1108 analyzer and were within the 0.5 % of the
theoretical values. Column chromatography was performed on silica gel (Merck, 60-120 mesh).
General procedure for the preparation of chalcones (3a-h)
To a solution of 4-hydroxy-3,5-dinitroacetophenone (0.01 mol) and substituted aromatic
aldehyde (0.01 mol) in ethanol (5 mL) taken in 100 mL borosil flask, was added
montmorrilonite K 10 clay (4g). The mixture was uniformly mixed with glass rod and air
dried to remove the solvent. Adsorbed material was irradiated inside a microwave oven for
4-6 min. at medium power level (600 W). After the completion of the reaction (monitored
by TLC), the reaction mixture was cooled at room temperature and the product was
extracted with ethanol (2x20 mL). Removal of the solvent and subsequent recrystallisation
with ethanol resulted analytical samples of 3a-h. The scheme of the synthesis of title
compounds is shown in Figure 1 and the Comparison of reaction times and yields of
compound (3a-h) under microwave and classical methods is showing in Table 1.
-
O
+
O
N
O
[ 2 ]
Y
HO
+
O
Compounds
X
Y
X
CH3
-
+
H
OCH3
H
3a
3b
3c
3d
3e
3f
O
N
(1)
(2)
H
Br
H
Cl
H
O
H
Br
H
Cl
-
O
+
H
H
OH
CH3
3g
3h
O
N
N
O
HO
Y
Y
-
+
O
X
O
[ 3a - h ]
(3a-h)
Figure 1. Scheme of the synthesis of chalcones (3a – h)

Microwave Induced Improved Synthesis
667
Table 1. Comparison of reaction times and yields of compound (3a-h) under microwave and
classical methods
Reaction time
MW Classical,
Yield, %
M.P.
oC
Entry
Chalcones
MW Classical
min.
7
h
3a
212-213
108-109
17
82
52
3b
3c
3d
8
6
18
18
80
78
50
48
204-205
104-105
6
20
82
52
3e
3f
209-210
95-96
7
7
20
18
85
82
50
49
3g
3h
99-100
8
7
21
22
82
80
50
55
180-181
2(E)-1-(4-hydroxy-3,5-dinitrophenyl)-3-(4-methoxy phenyl)propenone (3a)
1
Dark yellow crystals, H NMR (500 MHz, CDCl3) δ:8.9 (d. J=8, 2H), 12.1 (s, H, OH of
acetophenone) 7.4 (d, J=8, 2H), 7.1 (d, J=8, 2H), 3.9 (s,3H,OCH3) 7.78 (d, J=8, H)-COCH=,
7.51 (d, J=16, H, =CH-Ar); 13C-NMR (500 MHz,CDCl3) δ= 26.46, 77.01, 114.71, 116.29,
130.77, 130.97, 147.65. IR (KBr) / cm-1: 3433 cm-1(-OH), 1664 cm1(C=O), 1633 cm-1
(CH=CH), 1118 cm-1 (-OCH3), 1358 cm-1 (-NO2) Anal.Calcd for C16H12O7N2: C, 55.8%, H,
3.48%, N, 8.18%.found C, 55.01%, H, 3.25%, N, 8.13%.

668
K. L. AMETA et al.
(2E)-1-(4-hydroxy-3,5-dinitrophenyl)-3-(phenyl)propenone (3b)
Light red crystals, 1H NMR (500 MHz δ:8.9 (d.J=8,2H), 12.1(s,H, OH of acetophenone) 7.1-
7.8 (m,5H) Phenyl,7.75 (d,J=16,H) -COCH=, 7.5 (d,J=16,H) =CH-Ar. 13C NMR (500 MHz,
-1
CDCl3) δ= 26.27, 77.05, 128.94, 129.20, 130.69, 137.51, 152.51,1 92.57. IR (KBr) / cm : 3432 cm-1
(-OH), 1693 cm-1 (C=O), 1630 cm-1 (CH=CH), 1360 cm-1 (-NO2) Anal. Calcd for
C15H10O6N2: C, 57.32%, H, 3.18%, N, 8.95% found C, 55.18%, H, 3.12%, N,9.88%.
(2E)-3-(2-bromophenyl)-3-(4-hydroxy-3,5-dinitrophenyl)propenone (3c)
Light yellow crystals, 1H NMR (500 MHz,CDCl3) δ:8.9(d.J=8,2H),12.1(s,H, OH of
acetophenone) 7.4(d, J=8,H),7.3(t, J=8, H), 7.2 (t, J=8, H), 7.5 (d, J=8, H), 7.85
(d, J=16, H) -COCH=, 7.59 (d, J=16, H) =CH-Ar. 13C NMR (500 MHz,CDCl3)
δ= 30.10, 77.01, 128.12, 131.00,132.30, 133.83, 146.11, 165.71, 171.67. IR (KBr) / cm-1:
3434 cm-1 (-OH) 1668 cm-1 (C=O), 1632 cm-1 (CH=CH), 837 cm-1 (C-Br), 1352 cm-1
(NO2) Anal. Calcd for C15H9O6N2Br: C, 45.8%, H, 2.28%, N, 7.18% .found C,
45.48%, H, 2.25%, N, 7.12%.
(2E)-3-(4-bromophenyl)-1-(4-hydroxy-3,5-dinitrophenyl) propenone (3d)
1
Dark yellow crystals; H NMR (500 MHz, CDCl3 δ:8.9 (d. J=8, 2H), 12.1 (s,H, OH of
acetophenone) 7.6 (d, J=8, 2H) ,7.2 (d, J=8, 2H), 7.77 (d, J=18, H) -COCH=, 7.49
(d,J=16,H) =CH-Ar. 13C NMR (500 MHz, CDCl3) δ= 26.24, 77.02, 130.23, 130.83, 132.50,
137.52, 152.22, 192.49. IR (KBr) / cm-1: 3430 cm-1 (-OH), 1693 cm-1 (C=O), 1631 cm-1
(CH=CH), 1360 cm-1 (-NO2), 848 (C-Br) Anal. Calcd for C15H9O6N2Br: C, 45.8%, H,
2.29%, N, 7.18%. found C, 45.6%, H, 2.25%, N, 7.12%.
(2E)-3-(2-chlorophenyl)-1-(4-hydroxy-3, 5-dinitrophenyl) propenone (3e)
1
Light yellow crystals, H NMR (500 MHz, CDCl3) δ:8.9 (d .J = 8, 2H), 12.1 (s, H, OH of
acetophenone) 7.5 (d, J = 8, H), 7.55 (t, J = 8, H), 7.40 (t, J = 8, H), 7.77 (d, J = 8, H), 7.85
(d, J = 16, H) -COCH=, 7.60 (d, J = 16, H) =CH-Ar. 13C NMR (500 MHz, CDCl3) δ =
30.92, 77.01, 127.31, 128.91, 130.95, 132.36, 152.04, 184.57,. IR (KBr) / cm-1: 3434 cm-1
(-OH), 1668 cm-1 (C=O), 1632 cm-1 (CH=CH), 825 cm-1 (C-Cl), 1363 cm-1 (-NO2) Anal.
Calcd for C15H9O6N2Cl: C, 51.7%, H, 2.58%, N, 8.05% .found C, 51.48%, H, 2.25%,
N, 8.03%.
(2E)-3-(4-chlorophenyl)-1-(4-hydroxy-3, 5-dinitrophenyl) propenone (3f)
1
Dark yellow crystals, H NMR (500 MHz, CDCl3 δ:8.9 (d. J = 8,2H), 12.1 (s, H, OH of
acetophenone) 7.6 (d, J = 8,2H) ,7.4 (d, J = 8 ,2H), 7.78 (d, J = 16,H) -COCH=, 7.50 (d, J =
16,H) =CH-Ar. 13C NMR (500 MHz, CDCl3) δ= 26.27, 77.04, 128.08, 128.89, 130.68,
137.51, 152.11, 192.56. IR (KBr) / cm-1: 3432 cm-1 (-OH), 1693 cm-1 (C=O), 1631 cm-1
(CH=CH), 1360 cm-1 (-NO2), 814 cm-1 (C-Cl) Anal.Calcd for C15H9O6N2Cl: C, 51.8%, H,
2.58%, N, 8.05%.found C, 51.6%, H, 2.23%, N, 8.03%.
(2E)-1-(4-hydroxy-3,5-dinitrophenyl)-3-(4-hydroxyphenyl) propenone (3g)
1
Dark yellow crystals, H NMR (500 MHz, CDCl3 δ: 8.9 (d.J = 8,2H),12.1 (s, H, OH of
acetophenone) 7.3 (d, J=8, 2H), 7.5 (d,J=8, 2H), 13.1 (s, H, OH) 7.73 (d,J = 16,H,COCH=,
7.49 (d,J = 16,H) =CH-Ar. 13C NMR (500 MHz, CDCl3) δ= 26.24, 77.04, 128.08, 130.68,
132.38, 137.52, 152.11, 192.59. IR (KBr) / cm-1: 3420 cm-1(-OH), 1693 cm-1 (C=O), 1630 cm-1
(CH=CH), 1360 cm-1 (-NO2), 3508 cm-1 (C-OH) Anal. Calcd for C15H10O7N2: C, 54.5 %, H,
3.03%, N, 8.51% .found C, 53.99%, H, 2.98%, N, 8.48%.

Microwave Induced Improved Synthesis
669
(2E)-1-(4-hydroxy-3,5-dinitrophenyl)-3-(4-methyl phenyl)propenone(3h)
1
Spiny yellow crystals, H NMR (500 MHz, CDCl3) δ:8.9 (d.J=8,2H), 12.1 (s,H, OH of
acetophenone) 7.2(d, J=8,2H) ,7.56(d,J=8,2H), 2.35(s, 3H, -CH3 ) 7.71(d, J=16,H)-COCH =,
7.50 (d,J=16,H = CH-Ar). 13C NMR (500 MHz, CDCl3) δ= 30.93, 77.02, 129.97, 130.68,
130.84, 131.29, 148.54, 184.45. IR (KBr) / cm-1: 3434 cm-1 (-OH), 1665 cm-1 (C=O), 1628 cm-1
(CH=CH), 1366 cm-1 (-NO2), 2927cm-1 (C-CH3) Anal. Calcd for C16H12O6N2: C, 58.5%, H,
3.65%, N, 8.55% found C, 58.02%, H, 2.98%, N, 8.52%.
Results and Discussion
Antimicrobial activity
The newly synthesized compounds (3a-h) were screened for their antibacterial activity against
Escherichia coli, Staphylococcus aureus and antifungal activity against Alternaria alternate by
measuring the zone of inhibition in mm. The antimicrobial activity was performed by cup plate
method28 at concentration 500 µg / mL and reported in Table 2. Nutrient agar and Czapex Dox
agar was employed as culture medium for antibacterial and antifungal respectively. DMSO
was used as solvent control for antimicrobial activity. Tetracycline and fluconazole were used
as standard for antibacterial and antifungal activities respectively.
Table 2. Antimicrobial activity of synthesized compounds (3a-h)
Antibacterial
Zone of inhibition in mm
S. aureus
Antifungal
Compounds.
E. coli
A. alternate
10
6
7
4
8
6
3a
3b
8
5
9
3c
3d
12
11
13
8
7
13
5
6
8
10
6
3e
3f
3g
14
7
7
1
3h
Terracycline
Fluconazol
16
-
13
-
-
16
Conclusion
From the results of antimicrobial screening it was observed that all the compounds exhibited
activity against all the microorganisms employed. According to the structure activity
relationship, marked inhibition in bacteria was observed in the compounds (3a, 3c, 3d, 3f
and 3g) whereas other compounds show moderate to good activity. Antifungal screening
data also revealed that compounds (3d, 3g) imparted maximum activity to the compounds,
whereas other compounds showed moderate to good activity.
Acknowledgment
The authors are thankful to Prof. B. L. Verma, Retd. Professor of Chemistry, M. L. S.
University Udaipur, Dr. S. Baijal, Dean, FASC, MITS University and Mr. K. K. Maheshwari,
G. M. Finance, MITS University for their constant encouragement during this work. Authors
are also thankful to the Head, Sophisticated Analytical Instrument Facility, Indian Institute
of Technology, Madras for spectral analysis.

670
K. L. AMETA et al.
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