Synthesis, antimicrobial and DNA cleavage studies of some 4-aryloxymethylcoumarins obtained by reaction of 4-bromomethylcoumarins with bidentate nucleophiles

Article abstract of DOI:10.1007/s00044-011-9785-z

Symmetrical bidentate nucleophiles such as resorcinol have been made to react with 4-bromomethylcoumarins in a cascaded manner to obtain mono and bis-4-aryloxymethylcoumarins by a room temperature allylic nucleophilic displacement. Unsymmetrical nucleophiles such as 3-acetylaminophenol and 3-diethylaminophenol have been used to generate 4-aryloxymethylcoumarins. All the compounds have been analyzed by spectralmethods and subjected to preliminary antibacterial, antifungal and DNA cleavage studies. The results showed that the compounds bearing methoxy, chloro and bromo substituents at C6-position of coumarin showed higher activity. Springer Science+Business Media, LLC 2011.

Full text of DOI:10.1007/s00044-011-9785-z

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2012) 21:2603–2614
DOI 10.1007/s00044-011-9785-z
ORIGINAL RESEARCH
Synthesis, antimicrobial and DNA cleavage studies
of some 4-aryloxymethylcoumarins obtained by reaction
of 4-bromomethylcoumarins with bidentate nucleophiles
•
Shabana Banu N. Makandar Mahantesha Basanagouda
•
•
Manohar V. Kulkarni Pranesha Vijaykumar P. Rasal
•
Received: 16 February 2011 / Accepted: 16 August 2011 / Published online: 30 August 2011
Ó Springer Science+Business Media, LLC 2011
Abstract Symmetrical bidentate nucleophiles such as res-
orcinol have been made to react with 4-bromomethylcouma-
rins in a cascaded manner to obtain mono and bis-4-
aryloxymethylcoumarins by a room temperature allylic
nucleophilic displacement. Unsymmetrical nucleophiles such
as 3-acetylaminophenol and 3-diethylaminophenol have been
used to generate 4-aryloxymethylcoumarins. All the com-
pounds have been analyzed byspectralmethods and subjected
to preliminary antibacterial, antifungal and DNA cleavage
studies. The results showed that the compounds bearing
methoxy, chloro and bromo substituents at C6-position of
coumarin showed higher activity.
(Trenor et al., 2004) properties. They have been reported to
possess antibacterial (Khan et al., 2004; Appendino et al.,
2004), antiinflammatory (Silvan et al., 1996; Ghate et al.,
2003; Kontogiorgis and Litina, 2005), antioxidant (Ni-
colaides et al., 1998; Raj et al., 1998; Kontogiorgis and
Litina 2004; Kontogiorgis et al., 2006; Stanchev et al.
2009), anthelminthic (Lee et al., 1998), anticancer (Ito
et al., 2003) and anti-HIV (Thaisrivongs et al., 1994;
Kirkiacharian et al., 2002; Lee, 2004; Bedoya et al., 2005)
activities. The 4-substituted coumarin derivatives exhibited
antiplatelet (Roma et al. 2007), antitubercular (Manvar
et al., 2008), antioxidant (Stanchev et al., 2008) and
cytotoxic (Stanchev et al., 2008) activities. It has been
reported that the coumarin ethers at position 7 are potent
inhibitors of monoamine oxidase (MAO) (Catto et al.,
2006; Binda et al., 2007; Gnerre et al., 2000). The
3-substituted phenols have been associated with a variety
of biological properties and are useful synthons as well
(Durairaj, 2005; Marsini et al., 2007; Yadav and Badure,
2008; Halterman and Martyn, 2007; Tocco et al., 2009).
Recently we have also observed that linking of biocom-
patible fragments such as vanillin (Ghate et al., 2003) and
paracetamol (Shastri and Kulkarni, 2004) through an ether
linkage at C4-position of coumarin leads to molecular
motiffs with potential antiinflammatory and dual fluores-
cence properties. In continuation of our research on anti-
microbials (Basanagouda et al., 2009; Basanagouda et al.,
2010) and DNA cleavage (Jadhav et al., 2010), we report
the activity associated with 4-aryloxymethylcoumarins
derived from some meta-substituted phenols. The synthe-
sized compounds have been tested against six bacterial and
fungal strains. Furthermore, agarose gel electrophoresis
studies have also been done on their DNA cleavage ability
against Staphylococcus aureus, Escherichia coli and
Aspergillus niger at concentrations.
Keywords Coumarin Á Resorcinol Á 3-Aminophenol Á
3-Diethylaminophenol Á Microbial, DNA
Introduction
Coumarins are an important class of oxygen heterocycles,
which exhibit wide range of biological (Kulkarni et al.,
2006; Fylaktakidou et al., 2004) and photo-physical
S. B. N. Makandar Á M. Basanagouda Á M. V. Kulkarni (&)
Post-Graduate Department of Chemistry, Karnatak University,
Dharwad, Karnataka 580 003, India
e-mail: manohar274@gmail.com
S. B. N. Makandar
S.D.M. College of Engineering and Technology, Dharwad,
Karnataka 580 002, India
Pranesha Á V. P. Rasal
Department of Pharmacology, KLE’s College of Pharmacy,
Belgaum, Karnataka 590 010, India
123

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Med Chem Res (2012) 21:2603–2614
Br
O
R
O
O
OH
0 - 5 oC
Conc. H2SO4
O
Br
O
OH
N
a
d
R
R
R
O
O
O
O
O
O
1 (a-g)
2 (a-g)
5 (a-g)
c
b
e
O
O
O
N
H
O
R
R
R
O
3 (a-g)
Reagents and conditions: (a) resorcinol, K2CO3, acetone, stirr, 24 h
O
O
O
O
O
4 (a-g)
(b) 2 equivalents of 1, resorcinol, K2CO3, acetone, stirr, 24 h
(c) 3-hydroxyacetanilide, K2CO3, acetone, stirr, 24 h
(d) 3-diethylaminophenol, K2CO3, acetone, stirr, 24 h
(e) 1 (R = R), K2CO3, acetone, stirr, 24 h
Scheme 1 Synthesis of 4-aryloxymethylcoumarins
Chemistry
resonated at d 4.6 ppm, whereas the corresponding 4-a-
ryloxymethylcoumarins exhibited this peak at around d
5.2 ppm.
The required 4-bromomethylcoumarins 1 was prepared by
the Pechmann cyclisation of substituted phenol with
4-bromoethylacetoacetate using sulphuric acid as the con-
densing agent (Kulkarni and Patil, 1981). Resorcinol,
3-acetylaminophenol and 3-diethylaminophenol were used
during this work and the ethers 2, 4 and 5, respectively
were obtained under standard acetone–potassium carbonate
conditions at room temperature (Scheme 1). Formation of
Pharmacology
Antibacterial activity
Standard strains were procured from the microbial
type culture collection and Gene Bank (MTCC), Insti-
tute of Microbial Technology, Chandigarh, India. The
1
ethers was indicated by the difference in H NMR spectra.
The methylene protons in 4-bromomethylcoumarins
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Med Chem Res (2012) 21:2603–2614
2605
Table 1 Results of antibacterial activities of compounds 2, 3, 4 and 5 MICs (lg/ml)
Compound
R
Gram positive
Gram negative
S. faecalis
S. aureus
B. subtilis
P. aeruginosa
K. pneumoniae
E. coli
2a
6-CH3
7-CH3
5,6-benzo
7,8-benzo
6-OCH3
6-Cl
15 (12.5)
16 (12.5)
14 (12.5)
13 (25)
13 (12.5)
14 (12.5)
11 (25)
15 (12.5)
14 (12.5)
12 (25)
14 (25)
13 (12.5)
13 (12.5)
15 (12.5)
14 (12.5)
21 (6.25)
19 (6.25)
19 (6.25)
12 (12.5)
13 (12.5)
14 (12.5)
16 (6.25)
20 (6.25)
18 (6.25)
17 (6.25)
12 (12.5)
14 (12.5)
15 (12.5)
15 (12.5)
21 (6.25)
19 (6.25)
18 (6.25)
13 (125)
14 (12.5)
15 (12.5)
16 (12.5)
20 (6.25)
19 (6.25)
18 (6.25)
21 (6.25)
8 (50)
2b
16 (12.5)
18 (12.5)
19 (6.25)
25 (6.25)
24 (6.25)
23 (6.25)
13 (25)
9 (50)
2c
12(25)
2d
10 (25)
12 (25)
13 (25)
18 (12.5)
17 (12.5)
15 (12.5)
–
2e
21 (6.25)
22 (6.25)
18 (6.25)
16 (12.5)
16 (12.5)
11 (25)
20 (6.25)
21 (6.25)
19 (6.25)
14 (12.5)
12 (25)
18 (6.25)
20 (6.25)
17 (6.25)
14 (12.5)
14 (12.5)
12 (25)
2f
2g
6-Br
3a
6-CH3
7-CH3
5,6-benzo
7,8-benzo
6-OCH3
6-Cl
3b
14 (25)
–
3c
12 (25)
17 (12.5)
17 (12.5)
24 (6.25)
22 (6.25)
21 (6.25)
16 (12.5)
16 (12.5)
18 (12.5)
19 (6.25)
25 (6.25)
23 (6.25)
22 (6.25)
15 (25)
11 (25)
12 (25)
17 (12.5)
15 (12.5)
14 (12.5)
11 (25)
10 (25)
13 (25)
13 (25)
17 (12.5)
16 (12.5)
14 (12.5)
10 (50)
9 (50)
3d
12 (25)
11 (25)
11 (25)
3e
21 (6.25)
23 (6.25)
19 (6.25)
12 (25)
19 (6.25)
20 (6.25)
17(6.25)
14 (12.5)
14 (12.5)
13 (12.5)
12 (25)
18 (6.25)
19 (6.25)
16 (6.25)
15 (12.5)
15 (12.5)
11 (25)
3f
3g
6-Br
4a
6-CH3
7-CH3
5,6-benzo
7,8-benzo
6-OCH3
6-Cl
4b
14 (12.5)
10 (25)
4c
4d
12 (25)
13 (12.5)
19 (6.25)
20 (6.25)
17 (6.25)
14 (12.5)
13 (12.5)
11 (25)
4e
20 (6.25)
23 (6.25)
18 (6.25)
17 (6.25)
15 (6.25)
14 (12.5)
14 (12.5)
20 (6.25)
22 (6.25)
19 (6.25)
23 (6.25)
19 (6.25)
21 (6.25)
17 (6.25)
15 (12.5)
16 (12.5)
13 (12.5)
14 (12.5)
20 (6.25)
21 (6.25)
18 (6.25)
21 (6.25)
4f
4g
6-Br
5a
6-CH3
7-CH3
5,6-benzo
7,8-benzo
6-OCH3
6-Cl
5b
16 (12.5)
17 (12.5)
19 (6.25)
25 (6.25)
25 (6.25)
23 (6.25)
25 (6.25)
5c
14 (12.5)
13 (25)
17 (12.5)
15 (12.5)
15 (12.5)
18 (12.5)
5d
11 (25)
5e
18 (6.25)
20 (6.25)
17 (6.25)
20 (6.25)
5f
5g
6-Br
Ciprofloxacin
–
‘‘–’’ Indicates bacteria are resistant to the compounds at concentration [100 lg/ml; MIC values are given in parenthesis; MIC (lg/
ml) = minimum inhibitory concentration, i.e., lowest concentration to completely inhibit bacterial growth; zone of inhibition is expressed in mm
antibacterial activity of the synthesized compounds 2(a–g),
3(a–g), 4(a–g) and 5(a–g) was performed in vitro against
(i) Gram-positive bacteria: Streptococcus faecalis (MTCC
3382), Staphylococcus aureus (MTCC 3160) and Bacillus
subtilis (MTCC 297) and (ii) Gram-negative bacteria:
Pseudomonus aeruginosa (MTCC 1034), Klebsiella pneu-
moniae (MTCC 3384) and Escherichia coli (MTCC 1089)
by disc diffusion method (Cruickshank et al., 1975). Discs
measuring 6.25 mm in diameter were punched from
Whatman no. 1 filter paper. Batches of 100 discs were
dispensed to each screw-capped bottle and sterilized by dry
heat at 140°C for an hour. The test compounds were pre-
pared with different concentrations using dimethylform-
amide. About 1 ml containing 100 times the amount of
chemical in each disc was added to each bottle, which
contains 100 discs. The discs of each concentration were
placed in triplicate in nutrient agar medium seeded with
fresh bacteria separately. The incubation was carried out at
37°C for 24 h. Ciprofloxacin was used as a standard drug.
Solvent and growth controls were prepared and kept. Zones
of inhibition and minimum inhibitory concentrations
(MICs) were noted. The results of antibacterial studies are
given in Table 1.
Antifungal activity
The antifungal activities of the synthesized compounds
2(a–g), 3(a–g), 4(a–g) and 5(a–g) were performed against
the following standard fungal strains: Candida albicans,
Aspergillus fumigatus, Aspergillus niger, Penicillium
123

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Med Chem Res (2012) 21:2603–2614
Table 2 Results of antifungal activities of compounds 2, 3, 4 and 5 MICs (lg/ml)
Compound
R
C. albicans
A. fumigatus
A. niger
P. chrysogenum,
M. fuscus
F. oxysporum
2a
6-CH3
7-CH3
5,6-benzo
7,8-benzo
6-OCH3
6-Cl
10 (25)
16 (12.5)
16 (12.5)
15 (12.5)
15 (12.5)
17 (12.5)
21 (6.25)
18 (12.5)
17 (12.5)
17 (12.5)
15 (12.5)
15 (12.5)
18 (12.5)
22 (6.25)
18 (12.5)
17 (12.5)
16 (12.5)
17 (12.5)
17 (12.5)
21 (6.25)
22 (6.25)
20 (6.25)
16 (12.5)
15 (12.5)
14 (12.5)
15 (12.5)
19 (6.25)
22 (6.25)
20 (6.25)
22 (6.25)
19 (6.25)
19 (6.25)
17 (12.5)
17 (12.5)
20 (6.25)
24 (6.25)
21 (6.25)
17 (12.5)
16 (12.5)
16 (12.5)
15 (12.5)
18 (12.5)
24 (6.25)
19 (6.25)
20 (6.25)
19 (6.25)
19 (6.25)
19 (6.25)
21 (6.25)
22 (6.25)
20 (6.25)
18 (12.5)
18 (12.5)
17 (12.5)
17 (12.5)
20 (6.25)
22 (6.25)
20 (6.25)
24 (6.25)
18 (12.5)
18 (12.5)
16 (25)
14 (25)
8 (50)
2b
2c
9 (25)
14 (25)
9 (50)
14 (12.5)
13 (12.5)
19 (6.25)
20 (6.25)
17 (6.25)
9 (25)
13 (25)
12 (25)
12 (25)
16 (12.5)
17 (12.5)
13 (25)
–
2d
2e
16 (25)
13 (25)
20 (6.25)
22 (6.25)
19 (6.25)
16 (25)
19 (6.25)
21 (6.25)
18 (12.5)
16 (12.5)
15 (25)
2f
2g
6-Br
3a
6-CH3
7-CH3
5,6-benzo
7,8-benzo
6-OCH3
6-Cl
3b
3c
8 (25)
15 (25)
–
13 (12.5)
13 (12.5)
17 (6.25)
19 (6.25)
17 (6.25)
9 (25)
15 (25)
15 (25)
13 (25)
14 (25)
15 (12.5)
16 (12.5)
13 (25)
10 (50)
9 (50)
3d
3e
14 (25)
14 (25)
17 (12.5)
20 (6.25)
18 (12.5)
19 (6.25)
18 (12.5)
18 (12.5)
18 (12.5)
20 (6.25)
23 (6.25)
20 (6.25)
17 (12.5)
18 (12.5)
17 (12.5)
17 (12.5)
23 (6.25)
23 (6.25)
21 (6.25)
23 (6.25)
20 (6.25)
22 (6.25)
18 (12.5)
15 (25)
3f
3g
6-Br
4a
6-CH3
7-CH3
5,6-benzo
7,8-benzo
6-OCH3
6-Cl
4b
4c
9 (25)
16 (12.5)
15 (25)
15 (12.5)
16 (12.5)
19 (6.25)
20 (6.25)
16 (12.5)
10 (25)
12 (25)
11 (50)
16 (12.5)
16 (12.5)
13 (25)
9 (50)
4d
4e
16 (12.5)
21 (6.25)
22 (6.25)
19 (6.25)
16 (12.5)
16 (12.5)
14 (25)
4f
4g
6-Br
5a
6-CH3
7-CH3
5,6-benzo
7,8-benzo
6-OCH3
6-Cl
5b
5c
8 (25)
7 (50)
13 (12.5)
14 (12.5)
17 (6.25)
18 (6.25)
16 (12.5)
20 (6.25)
14 (25)
13 (25)
15
5d
5e
13 (25)
19 (6.25)
21 (6.25)
18 (12.5)
22 (6.25)
5f
16 (12.5)
14 (25)
17 (12.5)
5g
6-Br
Fluconazole
–
‘‘–’’ Indicates bacteria are resistant to the compounds at concentration [100 lg/ml; MIC values are given in parenthesis; MIC (lg/
ml) = minimum inhibitory concentration i.e., lowest concentration to completely inhibit bacterial growth; zone of inhibition is expressed in mm
chrysogenum, Mucor fuscus and Fusarium oxysporum in
dimethylsulfoxide (DMSO) by serial dilution method
(Khan, 1997). Sabourands agar media were prepared by
dissolving peptone (1 g), D-glucose (4 g) and agar (2 g) in
distilled water (100 ml) and adjusting the pH to 5.7. Nor-
mal saline was used to make a suspension of spore of
fungal strain for lawning. A loopful of particular fungal
strain was transferred to 3 ml of saline to get a suspension
of corresponding species. Agar media (20 ml) were poured
into each Petri dish. Excess of suspension was decanted
and the plates were dried by placing in an incubator at
37°C for 1 h using an agar punch, wells were made and
each well was labeled. A control was also prepared in
triplicate and maintained at 37°C for 3–4 days. Zone of
inhibition and minimum inhibitory concentration (MICs)
were noted. The activity of each compound was compared
with fluconazole as the standard drug. The results of anti-
fungal studies are given in Table 2.
DNA cleavage studies
DNA cleavage experiment
Preparation of culture media
DNA cleavage experiments were done according to the
literature (Brown, 1990). Nutrient broth (peptone, 10;
NaCl, 10 and Yeast extract, 5 g/l) was used for culturing of
S. aureus (Gram positive), E. coli (Gram negative) and
potato dextrose broth (potato, 250; dextrose, 20; in g/L)
were used for the culture of A. niger. The 50 ml media was
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Med Chem Res (2012) 21:2603–2614
2607
prepared and autoclaved for 15 min at 121°C, 15 lb pres-
sure. The autoclaved media were inoculated with the seed
culture. S. aureus and E. coli were incubated for 24 h and
A. niger for 48 h at 37°C.
spectrum of the compound 2a showed a molecular ion
at m/z 283 which is in conformity with the structure.
To evaluate the reactivity of one more free hydroxyl
group present in the ether, 2a is made to react with its
corresponding 4-bromomethylcoumarin 1 in equimolar
ratio resulted into the formation bis-coumarin 3a, which is
the same product obtained directly from resorcinol and
4-bromomethylcoumarin 1 in the ratio of 1:2.
Isolation of DNA
The fresh bacterial culture (1.5 ml) is centrifuged to obtain
the pellet which is then dissolved in 0.5 ml of lysis buffer
(100 mM Tris pH 8.0, 50 mM EDTA, 10% SDS). To this,
0.5 ml of saturated phenol was added and incubated at
55°C for 10 min. Then centrifuged at 10,000 rpm for
10 min and to the supernatant, equal volume of chloro-
form:isoamyl alcohol (24:1) and 1/20th volume of 3 M
sodium acetate (pH 4.8) were added. Then centrifuged at
10,000 rpm for 10 min and to the supernatant, three vol-
umes of chilled absolute alcohol were added. The precip-
itated DNA was separated by centrifugation and the pellet
was dried and dissolved in TAE buffer (10 mM Tris pH
8.0, 1 mM EDTA) and stored in cold condition.
The IR spectrum of bis[(4-phenoxymethyl)-6-methyl-
coumarin] (3a) (R = 6-CH3) showed only lactone carbonyl
stretching frequency at 1,713 cm-1 and the absence of
hydroxyl group. The PMR spectrum exhibited a singlet
because of CH3 protons at 2.46 d ppm, C4-CH2 at 5.25 d
ppm and C3-H at 6.64 d ppm. The aromatic protons reso-
nated in the range of 6.69–7.34 d ppm. This is further
confirmed by its mass spectrum that shows the molecular
ion peak m/z 477 [M ? Na] which agrees with the
molecular weight of the compound.
In the IR spectrum of N-[3-(6-methyl-coumarin-4-yl-
methoxy)-phenyl]-acetamide (4a) (R = 6-CH3), prominent
bands exhibited at 1,688, 1,736 and 3,318 cm-1 because of
amide CO, lactone CO and NH stretching vibrations,
respectively. The PMR spectrum exhibited singlets at 2.01,
2.41, 5.12 and 6.52 d ppm because of acetyl CH3, C6-CH3,
C4-CH2 and C3-H, respectively. The aromatic protons
resonated in the range of 6.52–7.21 d ppm. The ESI mass
spectrum shows the molecular ion peak m/z 324 which
conforms the structure.
Agarose gel electrophoresis
Cleavage products were analyzed by agarose gel electro-
phoresis method (Brown, 1990). The samples (50 lg and
25 lg) in DMF were added to isolated DNA of S. aureus,
E. coli and A. niger. The samples were incubated for 2 h at
37°C and then 20 ml of the DNA sample (mixed with
bromophenol blue dye at 1:1 ratio) was loaded carefully
into the electrophoresis chamber wells along standard DNA
marker containing TAE buffer (4.84 g Tris base, pH 8.0,
0.5 MEDTA/1 l) and finally loaded on agarose gel and the
constant 50 V of electricity was passed for around 30 min.
The gel was removed and stained with 2 mg/ml ethidium
bromide for 10–15 min and the bands were observed under
Vilberlourmate Gel documentation system and photo-
graphed to determine the extent of DNA cleavage. Then,
the results are compared with standard DNA marker.
In the IR spectrum of 4-(3-diethylamino-phenox-
ymethyl)-6-methyl-coumarin (5a) (R = 6-CH3) exhibited
lactone carbonyl stretching frequency at 1,714 cm-1. The
PMR spectrum exhibited a triplet at 1.18 d ppm because of
two CH3 of N(CH2-CH3)2, C6-CH3 resonated as a singlet at
2.44 d ppm, a quartet is observed at 3.35 because of two
CH2 of N(CH2-CH3)2, two singlets at 5.21 and 6.71
because of C4-CH2 and C3-H, respectively. The aromatic
protons resonated in the range of 6.33–7.39 d ppm. The ESI
mass spectrum that shows the molecular ion peak at m/z
338 which conforms the structure.
Results and discussion
Pharmacology
Synthesis
Antibacterial activity
The IR spectrum of 4-(3-hydroxy-phenoxymethyl)-6-
methylcoumarin (2a) (R = 6-CH3) showed lactone car-
bonyl stretching frequency at 1,723 cm-1 and stretching
frequency for hydroxyl group at 3,422 cm-1. The 1H NMR
spectrum exhibited a singlet because of CH3 protons at
2.45 d ppm, a singlet at 4.99 d ppm because of OH, which
is D2O exchangeable. C4-CH2 protons appeared as a singlet
at 5.22 and C3-H at 6.51 d ppm. The aromatic protons
resonated in the range of 6.62–7.41 ppm. The mass
The antibacterial activity of the synthesized compounds
2(a–g), 3(a–g), 4(a–g) and 5(a–g) was performed in vitro
against (i) Gram-positive bacteria: Streptococcus faecalis
(MTCC 3382), Staphylococcus aureus (MTCC 3160) and
Bacillus subtilis (MTCC 297) and (ii) Gram-negative
bacteria: Pseudomonus aeruginosa (MTCC 1034), Klebsi-
ella pneumoniae (MTCC 3384) and Escherichia coli
(MTCC 1089) by disc diffusion method (Cruickshank
et al., 1975).
123

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Med Chem Res (2012) 21:2603–2614
The results of antibacterial screening (Table 1) revealed
Gel electrophoresis technique works on the migration of
DNA under the influence of electric potential. Gel elec-
trophoresis pictures are shown in Figs. 1, 2, 3, 4, 5 and 6.
The photograph (Fig. 1) shows the molecular weight dif-
ferences compared with control and is the differentiating
criterion for the DNA cleaving ability of the tested com-
pounds with S. aureus. Control experiments using DNA
alone do not indicate any significant cleavage of DNA even
after the first, second, third and fourth set of each having
seven lanes corresponding to 2(a–g), 3(a–g), 4(a–g) and
5(a–g), respectively. In series methyl (a and b) and benzo
(c and d) substituents on coumarin do not show any
changes when compared with the control. It is interesting
to note that methoxy (e) chloro (f) and bromo (g) substit-
uents on C6-position of coumarin show difference in
molecular weight and tailing to a great extent which could
be attributed to the DNA cleavage (50 lg). To test the
DNA cleavage ability among the methoxy (e) chloro
(f) and bromo (g) substituents on coumarin, experiment
was carried out in 25 lg, which showed chloro derivative
2f as the most active compound (Fig. 2).
that all the tested compounds showed moderate-to-good
bacterial inhibition. In general, the compounds having
methoxy, chloro and bromo substituents at C6-position of
coumarin showed higher activity when compared with
other compounds for both Gram positive and Gram nega-
tive bacteria. Among methoxy, chloro and bromo substit-
uents, the chloro-substituted compounds 2f, 3f, 4f and 5f
exhibited activity comparable to ciprofloxacin for Gram
positive bacteria. The data reveal that the activity of sub-
stituents is in the order of chloro [ methoxy [ bromo.
Methoxy-substituted compounds 2e, 3e, 4e and 5e were
highly active against Gram negative bacteria comparable to
ciprofloxacin. The data reveal that the activity of substit-
uents is in the order of methoxy [ chloro [ bromo.
Antifungal activity
The antifungal activities of the synthesized compounds
2(a–g), 3(a–g), 4(a–g) and 5(a–g) were performed against
the following standard fungal strains: Candida albicans,
Aspergillus fumigatus, Aspergillus niger, Penicillium
chrysogenum, Mucor fuscus and Fusarium oxysporum in
dimethylsulfoxide (DMSO) by serial dilution method
(Khan, 1997).
Methoxy, chloro and bromo substituents showed DNA
cleavage ability of E. coli (Fig. 3). Among these, methoxy
compound (e) exhibited DNA cleavage ability at 25 lg
(Fig. 4).
The screening data of antifungal activity (Table 2)
revealed that compounds bearing methoxy, chloro and
bromo substituents at C6-position of coumarin showed
higher activity compared with the others. The activity of
chloro-substituted compounds 2f, 3f, 4f and 5f is compa-
rable with fluconazole in some cases. The order of fungi-
cidal activity is chloro [ methoxy [ bromo.
DNA cleavage studies
The DNA cleavage studies of all the synthesized 4-aryl-
oxymethylcoumarins 2(a–g), 3(a–g), 4(a–g) and 5(a–
g) have been carried out against S. aureus MTCC 3160), E.
coli (MTCC 1089) and fungus A. niger by agarose gel
electrophoresis method (Brown, 1990).
Fig. 2 Gel electrophoresis picture of 4-aryloxymethylcoumarins 2(e–
g), 3(e–g), 4(e–g) and 5(e–g) on DNA of S. aureus at 25 lg. Lane M:
DNA marker; Lane C: untreated DNA
Fig. 1 Gel electrophoresis picture of 4-aryloxymethylcoumarins 2(a–g), 3(a–g), 4(a–g) and 5(a–g) on DNA of S. aureus at 50 lg. Lane M: DNA
marker; Lane C: untreated DNA
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Fig. 3 Gel electrophoresis picture of 4-aryloxymethylcoumarins 2(a–g), 3(a–g), 4(a–g) and 5(a–g) on DNA of E. coli at 50 lg. Lane M: DNA
marker; Lane C: untreated DNA
Fig. 4 Gel electrophoresis
picture of 4-aryl-
oxymethylcoumarins 2(e–g),
3(e–g), 4(e–g) and 5(e–g) on
DNA of E. coli at 25 lg. Lane M:
DNA marker; Lane C: untreated
DNA
Fig. 5 Gel electrophoresis picture of 4-aryloxymethylcoumarins 2(a–g), 3(a–g), 4(a–g) and 5(a–g) on DNA of A. niger at 50 lg. Lane M: DNA
marker; Lane C: untreated DNA
Fig. 6 Gel electrophoresis
picture of 4-aryl-
oxymethylcoumarins 2(e–g),
3(e–g), 4(e–g) and 5(e–g) on
DNA of A. niger at 25 lg. Lane
M: DNA marker; Lane C:
untreated DNA
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Med Chem Res (2012) 21:2603–2614
Against DNA of A. niger, the methoxy, chloro and
m = multiplet. The mass spectra were recorded using
Agilent-single quartz LC–MS.
bromo substituents showed DNA cleavaging ability
(Fig. 5). Among these, chloro (f) derivative has been found
to be highly active at 25 lg (Fig. 6).
In summary, it can be seen that the some of the
4-aryloxymethyl coumarins exhibit growth inhibition of
the bacterial and fungal species. Methyl and benzo sub-
stituents on coumarin showed the inertness towards DNA.
Compounds possessing methoxy (e), chloro (f) and bromo
(g) substituents on C6-position of coumarin moiety inhibit
the growth of the pathogenic organisms by cleaving the
genome.
Synthesis
Synthesis of substituted-4-bromomethylcoumarins (1)
The required substituted-4-bromomethylcoumarin (1)
(Kulkarni and Patil, 1981) has been synthesized by the
Pechmann cyclisation of various phenols with 4-bromoe-
thylacetoacetate (Burger and Ullyot, 1947).
General procedure for synthesis of (2)
Conclusions
A mixture of resorcinol (1.10 g, 0.01 mol) and anhydrous
potassium carbonate (1.38 g, 0.01 mol) was stirred for 1 h
in dry acetone (30 ml). To this, 6-methyl-4-bromo-
methylcouamarin 1a (2.53 g, 0.01 mol) was added and the
stirring was continued for 24 h (monitored by TLC). Then,
the resulting reaction mixture poured to crushed ice. The
separated solid was filtered, washed with 1:1 HCl (30 ml)
and finally with water. Then, the product 2a was recrys-
tallized from suitable solvent. Similar procedure was fol-
lowed for the synthesis of 2(b–g).
A series of 4-aryloxymethylcoumarins 2(a–g), 3(a–g), 4(a–
g) and 5(a–g) with different groups at 3-position of phenol
have been synthesized. Antimicrobial screening reveals
that compounds with methoxy, chloro and bromo substit-
uents at C6-position of coumarin exhibited promising
activity. Among these three, chloro-substituted compounds
have been most active. In the case of Gram negative bac-
teria, methoxy-substituted compounds have been most
active. The order of activity of substituents is chloro [
methoxy [ bromo. The results of DNA cleavage studies
show that chloro-substituted compounds show greater
selectively towards S. aureus and A. niger, whereas
methoxy substitution was more active against E. coli.
These compounds can act as potent antimicrobials by
genome cleavage. Hence, it is concluded that there is
ample scope for further study in developing these as good
lead compounds as new antimicrobials.
4-(3-Hydroxy-phenoxymethyl)-6-methylcoumarin (2a)
Colorless solid (aqueous acetic acid); yield 78%; m.p.
1
180°C; IR (KBr, m cm-1): 1,723 (C=O), 3,422 (OH); H
NMR (300 MHz, CDCl3) d: 2.45 (s, 3H, C6-CH3), 4.99 (s,
1H, OH, D2O exchangeable), 5.22 (s, 2H, C4-CH2), 6.51 (s,
1H, C3-H), 6.62–7.41 (m, 7H, Ar-H); LCMS m/z: 283
[M ? 1]. Anal. calc. for C17H14O4: C, 72.33; H, 5.00;
Found: C, 72.28; H, 4.96.
Experimental
4-(3-Hydroxy-phenoxymethyl)-7-methylcoumarin (2b)
Materials
Colorless solid (aqueous acetic acid); yield 76%; m.p.
1
All the starting materials and reagents were purchased from
commercial suppliers and used after further purification.
238°C; IR (KBr, m cm-1): 1,717 (C=O), 3,417 (OH); H
NMR (300 MHz, CDCl3) d: 2.49 (s, 3H, C7-CH3), 4.95 (s,
1H, OH, D2O exchangeable), 5.23 (s, 2H, C4-CH2), 6.62 (s,
1H, C3-H), 6.66–7.46 (m, 7H, Ar-H). Anal. calc. for
C17H14O4: C, 72.33; H, 5.00; Found: C, 72.24; H, 4.92.
Physical measurements
Melting points were determined by open capillary method
and are uncorrected. All the compounds were analyzed
satisfactorily for C, H and N. IR spectra (KBr disc) were
1-(3-Hydroxy-phenoxymethyl)-benzo[f]coumarin (2c)
1
recorded on a Nicolet-5700 FT-IR spectrophotometer. H
Colorless solid (aqueous acetic acid); yield 80%; m.p.
1
NMR spectra were recorded on Bruker 300 MHz spec-
trometer using CDCl3 as a solvent and TMS as an internal
standard. The chemical shifts are expressed in d ppm scale
down field from TMS and proton signals are indicated as
s = singlet, d = doublet, t = triplet, q = quartet and
218°C; IR (KBr, m cm-1): 1,727 (C=O), 3,438 (OH); H
NMR (300 MHz, CDCl3) d: 3.35 (s, 1H, OH, D2O
exchangeable), 5.65 (s, 2H, C4-CH2), 6.67 (s, 1H, C3-H),
6.80–8.14 (m, 10H, Ar-H). Anal. calc. for C20H14O4: C,
75.46; H, 4.43; Found: C, 75.38; H, 4.32.
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4-(3-Hydroxy-phenoxymethyl)-benzo[h]coumarin (2d)
Colorless solid (aqueous acetic acid); yield 75%; m.p.
(300 MHz, CDCl3) d: 2.46 (s, 6H, C6-CH3), 5.25 (s, 4H,
C4-CH2), 6.69 (s, 2H, C3-H), 6.69–7.34 (m, 10H, Ar-H);
LCMS m/z: 477 [M ? Na]. Anal. calc. for C28H22O6: C,
74.33; H, 4.88; Found: C, 74.18; H, 4.79.
1
240°C; IR (KBr, m cm-1): 1,724 (C=O), 3,441 (OH); H
NMR (300 MHz, CDCl3) d: 3.53 (s, 1H, OH, D2O
exchangeable), 5.36 (s, 2H, C4-CH2), 6.63 (s, 1H, C3-H),
6.79–8.60 (m, 10H, Ar-H). Anal. calc. for C20H14O4: C,
75.46; H, 4.43; Found: C, 75.40; H, 4.39.
Bis[(4-phenoxymethyl)-7-methylcoumarin] (3b)
Colorless solid (aqueous acetic acid); yield 76%; m.p.
238°C; IR (KBr, m cm-1): 1,720 (C=O); 1H NMR
(300 MHz, CDCl3) d: 2.49 (s, 6H, C7-CH3), 5.23 (s, 4H,
C4-CH2), 6.62 (s, 2H, C3-H), 6.67–7.49 (m, 10H, Ar-H).
Anal. calc. for C28H22O6: C, 74.33; H, 4.88; Found: C,
74.22; H, 4.73.
4-(3-Hydroxy-phenoxymethyl)-6-methoxycoumarin (2e)
Colorless solid (aqueous acetic acid); yield 71%; m.p.
1
175°C; IR (KBr, m cm-1): 1,713 (C=O), 3,410 (OH); H
NMR (300 MHz, CDCl3) d: 3.81 (s, 3H, C6-OCH3), 4.52
(s, 1H, OH, D2O exchangeable), 5.22 (s, 2H, C4-CH2), 6.68
(s, 1H, C3-H), 6.71–7.34 (m, 7H, Ar-H). Anal. calc. for
C17H14O5: C, 68.45; H, 4.73; Found: C, 68.30; H, 4.62.
Bis[(4-phenoxymethyl)-benzo[f]coumarin] (3c)
Colorless solid (aqueous acetic acid); yield 78%; m.p.
230°C; IR (KBr, m cm-1): 1,727 (C=O); 1H NMR
(300 MHz, CDCl3) d: 5.65 (s, 4H, C4-CH2), 6.95 (s, 2H,
C3-H), 6.75–8.16 (m, 16H, Ar-H). Anal. calc. for
C34H22O6: C, 77.56; H, 4.21; Found: C, 77.42; H, 4.16.
4-(3-Hydroxy-phenoxymethyl)-6-chlorocoumarin (2f)
Colorless solid (aqueous acetic acid); yield 63%; m.p.
1
198°C; IR (KBr, m cm-1): 1,720 (C=O), 3,426 (OH); H
NMR (300 MHz, CDCl3) d: 4.40 (s, 1H, OH, D2O
exchangeable), 5.22 (s, 2H, C4-CH2), 6.63 (s, 1H, C3-H),
6.74–7.55 (m, 7H, Ar-H). Anal. calc. for C16H11ClO4: C,
63.48; H, 3.66; Found: C, 63.40; H, 3.58.
Bis[(4-phenoxymethyl)-benzo[h]coumarin] (3d)
Colorless solid (aqueous acetic acid); yield 72%; m.p.
258°C; IR (KBr, m cm-1): 1,729 (C=O); 1H NMR
(300 MHz, CDCl3) d: 5.60 (s, 4H, C4-CH2), 6.94 (s, 2H,
C3-H), 6.75–8.13 (m, 16H, Ar-H). Anal. calc. for
C34H22O6: C, 77.56; H, 4.21; Found: C, 77.47; H, 4.12.
4-(3-Hydroxy-phenoxymethyl)-6-bromocoumarin (2g)
Colorless solid (aqueous acetic acid); yield 58%; m.p.
1
210°C; IR (KBr, m cm-1): 1,723 (C=O), 3,430 (OH); H
Bis[(4-phenoxymethyl)-6-methoxycoumarin] (3e)
NMR (300 MHz, CDCl3) d: 4.36 (s, 1H, OH, D2O
exchangeable), 5.24 (s, 2H, C4-CH2), 6.65 (s, 1H, C3-H),
6.71–7.80 (m, 7H, Ar-H). Anal. calc. for C16H11BrO4: C,
55.36; H, 3.19; Found: C, 55.28; H, 3.11.
Colorless solid (aqueous acetic acid); yield 71%; m.p.
200°C; IR (KBr, m cm-1): 1,714 (C=O); 1H NMR
(300 MHz, CDCl3) d: 3.95 (s, 6H, C6-OCH3), 5.22 (s, 4H,
C4-CH2), 6.55 (s, 2H, C3-H), 6.70–7.35 (m, 10H, Ar-H).
Anal. calc. for C28H22O8: C, 69.13; H, 4.56; Found: C,
69.02; H, 4.48.
General procedure for synthesis of (3)
A mixture of resorcinol (1.10 g, 0.01 mol) and anhydrous
potassium carbonate (2.76 g, 0.02 mol) was stirred for 1 h
in dry acetone (30 ml). To this, 6-methyl-4-bromo-
methylcouamarin 1a (5.06 g, 0.02 mol) was added and the
stirring was continued for 24 h (monitored by TLC). Then,
the resulting reaction mixture poured to crushed ice. The
separated solid was filtered, washed with 1:1 HCl (30 ml)
and finally with water. Then the product 3a was recrys-
tallized from suitable solvent. Similar procedure was fol-
lowed for the synthesis of 3(b–g).
Bis[(4-phenoxymethyl)-6-chlorocoumarin] (3f)
Colorless solid (aqueous acetic acid); yield 60%; m.p.
262°C; IR (KBr, m cm-1): 1,719 (C=O); 1H NMR
(300 MHz, CDCl3) d: 5.22 (s, 4H, C4-CH2), 6.74 (s, 2H,
C3-H), 7.28–7.57 (m, 10H, Ar-H). Anal. calc. for
C26H16Cl2O6: C, 63.05; H, 3.26; Found: C, 63.00; H, 3.17.
Bis[(4-phenoxymethyl)-6-bromocoumarin] (3g)
Bis[(4-phenoxymethyl)-6-methylcoumarin] (3a)
Colorless solid (aqueous acetic acid); yield 66%; m.p.
236°C; IR (KBr, m cm-1): 1,721 (C=O); 1H NMR
(300 MHz, CDCl3) d: 5.24 (s, 4H, C4-CH2), 6.68 (s, 2H,
Colorless solid (aqueous acetic acid); yield 82%; m.p.
268°C; IR (KBr, m cm-1): 1,713 (C=O); 1H NMR
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Med Chem Res (2012) 21:2603–2614
N-[3-(2H-benzo[h]coumarin-4-ylmethoxy)-phenyl]-
acetamide (4d)
C3-H), 7.12–7.96 (m, 10H, Ar-H). Anal. calc. for
C26H16Br2O6: C, 53.45; H, 2.76; Found: C, 53.20; H, 2.59.
Colorless solid (acetic acid); yield 72%; m.p. 208°C; IR
(KBr, m cm-1): 1,656 (amide C=O), 1,726 (lactone C=O),
3,306 (NH); H NMR (300 MHz, CDCl3) d: 2.04 (s, 3H,
General procedure for synthesis of (4)
1
A mixture of 3-hydroxyacetanilide (1.51 g, 0.01 mol) and
anhydrous potassium carbonate (1.38 g, 0.01 mol) was
stirred for 1 h in dry acetone (30 ml). To this, 6-methyl-4-
bromomethylcouamarin 1a (2.53 g, 0.01 mol) was added
and the stirring was continued for 24 h (monitored by
TLC). Then, the resulting reaction mixture poured to cru-
shed ice. The separated solid was filtered, washed with 1:1
HCl (30 ml) and finally with water. Then the product 4a
was recrystallized from suitable solvent. Similar procedure
was followed for the synthesis of 4(b–g).
COCH3), 5.31 (s, 2H, C4-CH2), 6.64 (s, 1H, C3-H),
7.10–8.43 (m, 10H, Ar-H), 9.50 (s, 1H, NH, D2O
exchangeable); LCMS m/z: 360 [M ? 1]. Anal. calc. for
C22H17NO4: C, 73.53; H, 4.77, N, 3.90; Found: C, 73.43;
H, 4.68, N, 3.82.
N-[3-(6-Methoxy-coumarin-4-ylmethoxy)-phenyl]-
acetamide (4e)
Colorless solid (acetic acid); yield 70%; m.p. 202°C; IR
(KBr, m cm-1): 1,670 (amide C=O), 1,705 (lactone C=O),
1
3,305 (NH); H NMR (300 MHz, CDCl3) d: 2.04 (s, 3H,
COCH3), 3.71 (s, 3H, C6-OCH3), 5.18 (s, 2H, C4-CH2),
6.65 (s, 1H, C3-H), 6.61–7.54 (m, 7H, Ar-H), 9.54 (s, 1H,
NH, D2O exchangeable). Anal. calc. for C19H17NO5: C,
67.25; H, 5.05, N, 4.13; Found: C, 67.21; H, 5.00, N, 4.08.
N-[3-(6-Methyl-coumarin-4-ylmethoxy)-phenyl]-acetamide
(4a)
Colorless solid (acetic acid); yield 82%; m.p. 200°C; IR
(KBr, m cm-1): 1,688 (amide C=O), 1,736 (lactone C=O),
1
N-[3-(6-chloro-coumarin-4-ylmethoxy)-phenyl]-acetamide
(4f)
3,318 (NH); H NMR (300 MHz, CDCl3) d: 2.01 (s, 3H,
COCH3), 2.41 (s, 3H, C6-CH3), 5.12 (s, 2H, C4-CH2), 6.52
(s, 1H, C3-H), 6.52–7.21 (m, 7H, Ar-H), 8.52 (s, 1H, NH,
D2O exchangeable), LCMS m/z: 324 [M ? 1]. Anal. calc.
for C19H17NO4: C, 70.58; H, 5.30, N, 4.33; Found: C,
70.51; H, 5.24, N, 4.28.
Colorless solid (acetic acid); yield 71%; m.p. 198°C; IR
(KBr, m cm-1): 1,670 (amide C=O), 1,712 (lactone C=O),
1
3,297 (NH); H NMR (300 MHz, CDCl3) d: 2.21 (s, 3H,
COCH3), 5.21 (s, 2H, C4-CH2), 6.71 (s, 1H, C3-H), 6.93-
7.84 (m, 7H, Ar-H), 9.52 (s, 1H, NH, D2O exchangeable).
Anal. calc. for C18H14ClNO4: C, 62.89; H, 4.10, N, 4.07;
Found: C, 62.79; H, 4.02, N, 4.00.
N-[3-(7-Methyl-coumarin-4-ylmethoxy)-phenyl]-acetamide
(4b)
Colorless solid (acetic acid), yield 76%; m.p. 196°C; IR
(KBr, m cm-1): 1,666 (amide C=O), 1711 (lactone C=O),
3,342 (NH); H NMR (300 MHz, CDCl3) d: 2.14 (s, 3H,
N-[3-(6-bromo-coumarin-4-ylmethoxy)-phenyl]-acetamide
(4g)
1
COCH3), 2.52 (s, 3H, C7-CH3), 5.13 (s, 2H, C4-CH2), 6.58
(s, 1H, C3-H), 6.67–7.52 (m, 7H, Ar-H), 8.75 (s, 1H, NH,
D2O exchangeable). Anal. calc. for C19H17NO4: C, 70.58;
H, 5.30, N, 4.33; Found: C, 70.53; H, 5.21, N, 4.23.
Colorless solid (acetic acid); yield 69%; m.p. 205°C; IR
(KBr, m cm-1): 1,661 (amide C=O), 1,716 (lactone C=O),
3,310 (NH); H NMR (300 MHz, CDCl3) d: 2.18 (s, 3H,
COCH3), 5.28 (s, 2H, C4-CH2), 6.68 (s, 1H, C3-H),
6.73–7.76 (m, 7H, Ar-H), 9.42 (s, 1H, NH, D2O
exchangeable). Anal. calc. for C18H14BrNO4: C, 55.69; H,
3.63, N, 3.61; Found: C, 55.60; H, 3.52, N, 3.53.
1
N-[3-(3H-benzo[f]coumarin-1-ylmethoxy)-phenyl]-
acetamide (4c)
General procedure for synthesis of (5)
Colorless solid (acetic acid); yield 71%; m.p. 182°C; IR
(KBr, m cm-1): 1,660 (amide C=O), 1,728 (lactone C=O),
3,306 (NH); H NMR (300 MHz, CDCl3) d: 2.21 (s, 3H,
COCH3),5.64 (s, 2H, C4-CH2), 6.63 (s, 1H, C3-H),
6.79–7.12 (m, 10H, Ar-H), 9.52 (s, 1H, NH, D2O
exchangeable). Anal. calc. for C22H17NO4: C, 73.53; H,
4.77, N, 3.90; Found: C, 73.48; H, 4.70, N, 3.84.
A mixture of 3-diethylaminophenol (1.65 g, 0.01 mol) and
anhydrous potassium carbonate (1.38 g, 0.01 mol) was
stirred for 1 h in dry acetone (30 ml). To this, 6-methyl-4-
bromomethylcouamarin 1a (2.53 g, 0.01 mol) was added
and the stirring was continued for 24 h (monitored by
TLC). Then, the resulting reaction mixture poured to
1
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Med Chem Res (2012) 21:2603–2614
2613
crushed ice. The separated solid was filtered, washed with
1:1 HCl (30 ml) and finally with water. Then the product
5a was recrystallized from suitable solvent. Similar pro-
cedure was followed for the synthesis of 5(b–g).
C21H23NO4: C, 71.37; H, 6.56; N, 3.96 Found: C, 71.30; H,
6.42; N, 3.88.
4-(3-Diethylamino-phenoxymethyl)-6-chloro-coumarin (5f)
Colorless solid (ethanol); yield 67%; m.p. 176°C; IR (KBr,
4-(3-Diethylamino-phenoxymethyl)-6-methyl-coumarin
(5a)
1
m cm-1): 1,724 (C=O); H NMR (300 MHz, CDCl3) d:
1.18 (t, 6H, N(CH2-CH3)2), 3.38 (q, 4H, N(CH2-CH3)2),
5.18 (s, 2H, C4-CH2), 6.74 (s, 1H, C3-H), 7.16–7.60 (m,
7H, Ar-H). Anal. calc. for C20H20ClNO3: C, 67.13; H,
5.63; N, 3.91 Found: C, 67.02; H, 5.52; N, 3.86.
Colorless solid (ethanol), yield 83%; m.p. 132°C; IR (KBr,
1
m cm-1): 1,714 (C=O); H NMR (300 MHz, CDCl3) d:
1.18 (t, 6H, N(CH_2CH3)2), 2.44 (s, 3H, C6-CH3), 3.35 (q,
4H, N(CH2-CH3)2), 5.21 (s, 2H, C4-CH2), 6.71 (s, 1H,
C3-H), 6.33–7.39 (m, 7H, Ar-H); LCMS m/z: 338
[M ? 1].Anal. calc. for C21H23NO3: C, 74.75; H, 6.87; N,
4.15 Found: C, 74.68; H, 6.79; N, 4.08.
4-(3-Diethylamino-phenoxymethyl)-6-bromo-coumarin
(5g)
Colorless solid (ethanol); yield 61%; m.p. 144°C; IR (KBr,
1
4-(3-Diethylamino-phenoxymethyl)-7-methyl-coumarin
(5b)
m cm-1): 1,714 (C=O); H NMR (300 MHz, CDCl3) d:
1.19 (t, 6H, N(CH2-CH3)2), 3.36 (q, 4H, N(CH2-CH3)2),
5.24 (s, 2H, C4-CH2), 6.71 (s, 1H, C3-H), 6.38-7.49 (m, 7H,
Ar-H). Anal. calc. for C20H20BrNO3: C, 59.71; H, 5.01; N,
3.48 Found: C, 59.58; H, 4.92; N, 3.35.
Colorless solid (ethanol); yield 81%; m.p. 108°C; IR (KBr,
1
m cm-1): 1,714 (C=O); H NMR (300 MHz, CDCl3) d:
1.18 (t, 6H, N(CH_2CH3)2), 2.48 (s, 3H, C6-CH3), 3.37 (q,
4H, N(CH2-CH3)2), 5.22 (s, 2H, C4-CH2), 6.65 (s, 1H,
C3-H), 6.47–7.63 (m, 7H, Ar-H); LCMS m/z: 338
[M ? 1].Anal. calc. for C21H23NO3: C, 74.75; H, 6.87; N,
4.15 Found: C, 74.64; H, 6.76; N, 4.04.
Acknowledgment Authors thank the University Sophisticated
Instrumentation Centre (USIC), Karnatak University, Dharwad for the
spectral and analytical data. Shabana Banu N. Makandar and Mah-
antesha Basanagouda are grateful to Karnatak University, Dharwad
for University Research Studentships.
1-(3-Diethylamino-phenoxymethyl)-benzo[f]coumarin (5c)
Colorless solid (ethanol); yield 78%; m.p. 120°C; IR (KBr,
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