Synthesis of Some Bromo-Substituted 3-Aroyl Flavanones
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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
Mahalle
