Synthesis of some bromo-substituted 3-Aroyl flavanones and flavones

Article abstract of DOI:10.1155/2010/158274

A series of bromo-substituted 3-aroyl flavanones and flavones have been synthesized. The identities of the new compounds synthesized have been developed on the basis of usual chemical transformation and IR, NMR spectral studies.

Full text of DOI:10.1155/2010/158274

ISSN: 0973-4945; CODEN ECJHAO
E-Journal of Chemistry
2010, 7(4), 1359-1361
http://www.e-journals.net
Synthesis of Some Bromo-Substituted
3-Aroyl Flavanones and Flavones
P. R. MAHALLE and N. T. KHATY*
Priyardarshini College of Engineering, Nagpur, India.
prmahalle@rediffmail.com
Received 20 October 2009; Accepted 15 December 2009
Abstract: A series of bromo-substituted 3-aroyl flavanones and flavones
have been synthesized. The identities of the new compounds synthesized
have been developed on the basis of usual chemical transformation and IR,
NMR spectral studies.
Keywords: Bromo-substituted compounds, 3-Aroyl flavanones, Flavones, Synthesis.
Introduction
Chalcones, flavanones and flavones were reported to have antibacterial, antifungal,
anticancer, anti -HIV and anti-oxidant properties1-4. Flavanones and flavones play a pivotal
role in the field of heterocyclic chemistry. These acts as a backbone for the compounds
which possess diverse pharmacological and microbial activity5,6.
The present communication deals with the synthesis of bromo-substituted 3-aroyl
flavones by employing two procedures i. e. one by the oxidation of 3-aroyl flavanones in
presence SeO2 as oxidizing agent which involves refluxing period of about 18 h and other
method by using iodine crystal as the oxidizing agent which requires only 30 min. The
reaction was carried out in different solvents like DMSO, THF and dioxane.
Experimental
All the melting points reported are uncorrected. All the compounds synthesized were
characterized on the basis of usual chemical transformation and IR, NMR spectral studies7.
The IR spectra were recorded on a Perkin - Elmer FT-IR infrared spectrophotometer. The
1HNMR spectra were recorded on a Bruker-DRX 300 MHz NMR spectrophotometer using
TMS as an internal reference in DMSO-d6 as a solvent.
1-(2-Hydroxy -3-bromo-5-methyl-phenyl)-3-phenyl– 1, 3-propadione (1)
It was prepared by the classical Baker -Venkatraman transformation8,9 from 2-benzoyloxy -
3-bromo-5-methyl acetophenone using pulverized KOH in pyridine.

Synthesis of Some Bromo-Substituted 3-Aroyl Flavanones
1360
3-Benzoyl-6-methyl-8-bromo flavanone(3) and 4’Methoxy-3-benzoyl-6-methyl-8-
bromo flavanone(5)
3-Benzoyl-6-methyl-8-bromo flavanone (3) and 4’methoxy-3-benzoyl-6-methyl-8-bromo flavanone
(5) were prepared from the condensation of 1-(2-hydroxy-3-bromo-5-methyl-phenyl)-3-phenyl
1,3-propadione (1, 0.005 M) with benzaldehyde (2, 0.005 M) and anisaldehyde (4, 0.005 M)
respectively in ethanol in presence of few drops of piperidine (0.5 mL). The reactions were
carried out for 2 h. The products were recrystallised form ethanol- acetic acid mixture.
3-Benzoyl-6-methyl-8-bromo flavone (6) and 4’methoxy-3-benzoyl-6-methyl-8-
bromo flavone(7)
The target products were prepared by the oxidation of 3-benzoyl-6-methyl-8-bromo flavanone
(3) and 4’methoxy-3-benzoyl-6-methyl-8-bromo flavanone (5), respectively with SeO2 in
different solvents like DMF, THF and DMSO. The reaction mixture was refluxed for 18 h and
the formation of the products was ensured with the help of TLC. The same products were
prepared using Iodine as an oxidizing agent which just takes 30 min for the completion of the
reaction. The Spectral data of the synthesized product are described as below:
IR (cm-1): 1670(C=O), 2340(Ar-H), 1070(C-O-C), 1440(C=C). NMR: δ 7.0-7.4 (m,
12H Ar-H); δ 5.5-6.0(m, 2H,CH), δ 2.2-2.3(m,3H, CH3).
IR (cm-1) : 1690( C=O), 2360(Ar-H), 1050(C-O-C), 1450(C=C). NMR: δ 7.32-7.97
(m, 11H Ar-H); δ 5.5-5.9 (m, 2H, CH), δ 3.4-3.6(m, 3H, OCH3); δ 2.2-2.4(m, 3H,CH3).
IR (cm-1): 1650(C=O), 2370(Ar-H), 1060(C-O-C), 1450(C=C). NMR: δ 7.2-7.8 (m,
12H Ar-H); δ 2.2-2.3(m, 3H, CH3).
IR (cm-1): 1650(C=O), 2370(Ar-H), 1060(C-O-C), 1450(C=C). NMR: δ.4-8.0
(m,11H,Ar-H); δ3.6-3.8(m,3H,OCH3),δ2.34-2.46(m, 3H,CH3)
Results and Discussion
The bromo-substituted 3-aroyl flavanones were prepared from the condensation of diketone
with an aromatic aldehyde. The diketone was prepared by employing the classical Bekar-
Venkatraman synthesis. Thus 3-benzoyl-6-methyl-8-bromo flavanone (3) and 4’-methoxy-3-
benzoyl-6-methyl-8-bromo flavanone (5) were synthesized by the condensation of 1-(2-
hydroxy-3-bromo-5-methyl phenyl)-3-phenyl-1,3-propadione (1) with benzaldehyde (2) and
anisaldehyde (4) respectively in ethanol for two hours in presence of few drops of piperidine
(Scheme 1). The products were recrystallised from ethanol-acetic acid mixture.
Br
Br
2
O
OH
CHO
H3C
C
O
H3C
C
O
EtOH/ piperidine
C
O
O
3
1
OCH3
Br
4
Br
OH
C
O
O
CHO
H3CO
H3C
C
H3C
EtOH/ piperidine
C
O
O
O
5
1
Scheme 1

1361
N. T. KHATY et al.
In order to obtain the bromo-substituted 3-aroyl flavones, the flavanones 3 and 5 were
oxidized using SeO2 for the reaction time of 16 h in various solvents like THF, DMSO and
dioxane. Similarly, the same products were oxidized in presence of a single crystal of iodine
(I2) and it was observed that the reaction was completed just in 30 min.
Br
Br
O
SeO2 ,16hrs
O
O
i)
I2
, 30 min
ii)
H3C
C
O
H3C
C
O
O
3
6
OCH3
OCH3
Br
Br
O
SeO
2 ,16hrs
O
O
i)
I2
, 30 min
ii)
H3C
C
O
H3C
C
O
O
7
5
Scheme 2
Table 1. Characteristic data of the synthesized compounds
C, H analysis %
Molecular Yield,
Formula
Rf (n-hexane:
EtOAc)
Product
M.p., °C
C, Found
(Calcd.)
H, Found
(Calcd.)
%
C23H17BrO3
C24H19BrO4
C23H15BrO3
C24H17BrO4
75 137-138
75 149-151
65 189-191
70 196-199
0.76( 3:2)
0.79( 3:2)
0.86( 3:2)
0.64( 3:2)
65.61(65.57) 4.05(4.07)
63.90(63.87) 4.22(4.24)
65.85(65.89) 3.59(3.61)
64.10(64.16) 3.83(3.81)
3
5
6
7
Acknowledgment
Authors are thankful to RSIC, CDRI Lucknow for providing the spectra and also to Dr. M.
P. Singh, Principal Priyadarshini Engineering College, Nagpur for providing necessary
facilities.
References
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Birt D F, Hendrich S and Wang W, Pharmacol Ther., 2001, 90, 157.
Yu D, Chen C H, Brossi A and Lee K H, J Med Chem., 2004, 47, 4072-4082.
Ungwitayatrom J, Samee W and Pimthon J, J Mol Struct., 2004, 689, 99.
Geirger W B and Conn J E, J Amer Chem Soc.,1945, 67, 112.
Laliberate R, Manson J, Warik H and Medewar G, Can J Chem., 1968, 46, 1952-1956.
Hatzade K M, Taile V S, Gaidhane P K, Haldar A G M and Ingle V N, Indian J
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Baker W, J Chem Soc., 1933, 1381-1389.
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