3-(substituted Aryl)-1-benzofuranyl-2-propenones: Antimicrobial properties of some chalcones-type compounds and their 2-pyrazoline derivatives

Article abstract of DOI:10.1155/2011/806854

2-Acetylbenzofuran on condensation with furan-2-carboxaldehyde and pyrrole-2-carboxaldehyde in methanolic KOH solution yielded the corresponding benzofuran chalcones. These two compounds and nine benzofuran chalcones were synthesized before, were further

Full text of DOI:10.1155/2011/806854

ISSN: 0973-4945; CODEN ECJHAO
E-Journal of Chemistry
http://www.e-journals.net
2011, 8(4), 1574-1581
3-(Substituted Aryl)-1-benzofuranyl-2-propenones:
Antimicrobial Properties of Some Chalcones-Type
Compounds and their 2-Pyrazoline Derivatives
DEMET COŞKUN§*, MISIR AHMEDZADE§ and SEVDA KIRBAĞ
§University of Fırat, Faculty of Science and Arts
Department of Chemistry, 23119 Elazığ-Turkey
University of Fırat, Faculty of Science and Arts
Department of Biology, 23119 Elazığ-Turkey
dcoskun@firat.edu.tr
Received 13 November 2010; Accepted 19 January 2011
Abstract: 2-Acetylbenzofuran on condensation with furan-2-carboxaldehyde
and pyrrole-2-carboxaldehyde in methanolic KOH solution yielded the
corresponding benzofuran chalcones. These two compounds and nine
benzofuran chalcones were synthesized before, were further reacted with
hydrazine hydrate in ethanol which led to the formation of
2-pyrazoline
derivatives. All the synthesized compounds were characterized by elemental
analysis, melting point determination, infrared spectroscopy and nuclear
magnetic resonance spectroscopy. Nine chalcone-type compounds and eleven
2-pyrazolines were evaluated for their biological activities against the six
bacteria and the three yeast and it was seen that thirteen compounds showed
activity. Four of them are chalcone-type compounds showed more or less
activity
Keywords: Benzofuran, Chalcone, Pyrazoline, Antimicrobial, Antifungal
Introduction
The various activities of the compounds possessing benzofuran, chalcone and pyrazoline
moiety are well known. The pyrazoline function is quite stable and has inspired chemists to
utilize this stable fragment in bioactive moieties to synthesize new compounds possessing
biological activities. Chalcones have various biological activities such as antioxidant1,2,
cytotoxic3, antiviral4,5, tyrosinase inhibitory6, antimalarial7,8, antibacterial9,10 and anti-
inflammatory11,12. Pyrazolines have been also reported to show a broad spectrum of biological
activities including antibacterial13,14, antifungal15, antioxidant14, anti-inflammatory15,16
cytotoxic17, antidepressant18, anti-tumoral19 and hypotensive20 activities.
,

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DEMET COŞKUN et al.
There are lots of environmental bacteria capable of causing a variety of life threatening
human infections. In this study, synthesis and characterization of two newly synthesized
chalcone-type compouns, 1-(benzofuran-2-yl)-3-(furan-2-yl)-2-propenone (1j) and 1-(benzofuran-
2-yl)-3-(pyrrol-2-yl)-2-propenone (1k) are described. Preparation of 2-pyrazolines
derivatives (2a-k) of these two compounds and the previously synthesized nine chalcone-
type compounds21 are reported. These chalcones and their 2-pyrazoline derivatives were
screened for their biological activities against six bacteria and three yeast.
Experimental
All chemicals were purchased from Fluka and Aldrich. All melting points were measured
using a differential scanning calorimeter (Shimadzu DSC-50) and are uncorrected.
1
Elemental analyses were performed on a Leco CHNS-932 apparatus. H- and 13C NMR
spectra were recorded on a Bruker AC 300 (300 MHz) and a Varian Mercury-Plas NMR
(400 MHz) in the specified deuterated solvents. Chemical shifts were expressed in ppm from
internal tetramethysilane. Infrared (IR) spectra were recorded as KBr pellets on a Perkin-
Elmer Spectrum One FTIR spectrometer.
General method for the synthesis of 3-(substituted aryl and heteroaryl)-1-
benzofuranyl-2-propenones (1j and 1k)
To a mixture of 2-acetylbenzofuran (2.187 g, 13.6 mmol) and the appropriate aldehyde
(13.6 mmol) in methanol (25 mL) a solution of sodium hydroxide (1 M, 18 mL) was added.
The reaction mixture was stirred for 3 h on a magnetic stirrer at room temperature and was
allowed to stand in refrigerator for overnight. The product was precipitated by pouring to
250 mL of cold water, was filtered and dried and crystallized from ethanol.
General method for the synthesis of 3-(2-benzofuranyl)-5-aryl and heteroaryl-2-
pyrazolines (2a-k)
The pyrazolines were synthesized as follow; Compounds 2a-k: The required chalcone-type
compound (example, 1a, 1.320 g, 5 mmol) was suspended in absolute ethanol (10 mL) and
stirred at room temperature. hydrazine hydrate (0.375 g, 7.5 mmol) was added and the
mixture stirred at reflux for 30 min. Upon cooling, the mixture was poured to cold water
(500 mL) and the precipitate was filtered off and washed with water and dried. The product
(2a) was crystallized from ethanol solution, yield: 1.029 g, 74%, mp: 211 oC.
The reflux time in the transformation of the chalcones to the pyrazolines varied from
10 to 60 min according to the kinds of the chalcones (10 min for 2j and 2e, 15 min for 2k,
30 min 2c and 2i, 40 min for 2a,2b,2d, 2f and 2 h and 60 min for 2g).
Evaluation of biological action
Six bacteria and three yeast were used as test organisms. These bacteria were
Staphylococcus aureus COWAN 1, Pseudomonas aeruginosa DMS 50071 SCOTTA,
Proteus vulgaris FMC 1, Escherichia coli ATCC 25922, Klebsiella pneumoniae FMC,
Bacillus megaterium DMS 32, and the yeasts were Candida albicans FMC 17, Candida
glabrata ATCC 66032 and Candida tropicalis ATCC 13803.
All of the synthesized compounds were screened against six bacteria and three yeasts
using the method given in literature22. The bacteria strains were inoculated into nutrient
broth and yeast strain inoculated into malt extract broth for 24 and 48 h, respectively. In the
disc- diffusion method, sterile Mueller-Hinton agar for bacteria and Malt extract agar for yeasts

Antimicrobial Properties of Some Chalcones-Type Compounds
1576
were separately inoculated with the test bacteria (105 bacteria per mL) and yeasts
(104 yeast per mL). In order to prepare the disc a part containing 1000 µg of compound from
its solution in DMSO was added onto the discs. In addition, disk containing DMSO were
placed (10 µL). Discs were applied on the solid agar medium by pressing slightly. Petri dishes
o
o
were placed at 4 C for 2 h. The bacteria samples were incubated at 35 0.1 C for 24 h and
yeast samples were incubated at 25 0.1 oC for 72 h. At the end of the period, inhibition zones
were measured in millimeter. The inhibition zone of compound was calculated by subtracting
that of pure DMSO from the zone of solution in DMSO of the compound.
Results and Discussion
This work is the second part of the studies on 3-(substituted aryl)-1-benzofuranl-2-
propenones and describes the synthesis and characterization of 2–pyrazoline derivatives
(2a-k) from the chalcones (1a-i) given previously21 and two new chalcones (1j and 1k) (Scheme 1)
and the biological activities of the twenty products. The synthesized chalcones compounds
were suspended in absolute ethanol, hydrazine hydrate was added and the mixture stirred at
reflux for a period of 10-60 min as depending on the kind of chalcones. The cyclization of
chalcones were carried out at a short period of time13,14. The cyclization of some chalcones
with hydrazine hydrate was required to make a reflux of 7 h in ethanol13. 2-Pyrazoline
derivatives were formed in 74-90 % yields13. The yields in formation of 3-(benzofuran-2-
yl)-5-(3-nitrophenyl)-2-pyrazoline (2f) and bispyrazoline (2h) are 60% and 45%,
respectively and relatively low.
Scheme 1. 2-Pyrazoline derivatives of some chalcone-type compounds
Structural characterization (FTIR, 1H- and 13C-NMR)
The newly synthesized two benzofuran chalcones (1j and 1k) showed the characteristic
absorption bands at 1659 cm-1 ( C=O stretching in 1j), at 1648 cm-1 (C=O stretching in 1k), at
3000-3150 cm-1 (=C-H stretching in furan ring) and at 3284 cm-1 (N-H stretching vibration in
pyrrole ring) in FTIR spectra. In 1H-NMR, the signals of olefinic β-H and α-H on double bond
conjugated to the carbonyl group were seen at 7.68 and 7.46 ppm as the both doublet (J≈15.02 Hz)
for 1j and at 7.68 and 7.52 ppm as the both doublet (J≈15.60 Hz) for 1k.
The disappearance of carbonyl absorptions between 1660-1640 cm-1 in FT-IR spectra of
chalcones21 and arising a new band between 3290-3360 cm-1 (NH stretching vibration)
1
confirm the cyclization to 2-pyrazoline derivatives of the chalcones. H-NMR spectra
of 2-pyrazolines derivatives show a signal due to NH proton between 8.09-6.92 ppm
as depending on substituted aromatic group bonded to pyrazoline ring at 5-position.

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DEMET COŞKUN et al.
Vicinal coupling constants of NH proton with pyrazoline ring proton at 5-position were
in the range of 1.60-2.54 Hz. 13C NMR spectra of two pyrazolines (2b and 2i) have also
been taken and they show characteristic signals for 2-pyrazoline ring carbons at about
151 ppm (C=N carbon), at about 41 ppm (CH2 ring carbon) and at about 60 ppm (CH
ring carbon).
Biological activity
All the synthesized chalcones and pyrazolines, except 1j and 1k, were screened in vitro for
antibacterial activity against Staphylococcus aureus COWAN 1, Pseudomonas aeruginosa
DMS 50071 SCOTTA, Proteus vulgaris FMC 1, Escherichia coli ATCC 25922, Klebsiella
pneumoniae FMC, Bacillus megaterium DMS 32 at absorbed 1000 µg per disc and for
antifungal activity against Candida albicans FMC 17, Candida glabrata ATCC 66032 and
Candida tropicalis ATCC 13803 at 1000 µg per disc by agar diffusion method22 given in
detail in experimental section .
Antibacterial and antifungal activities of the obtained compounds were measured as a
function of diameter of zone of inhibition (mm). DMSO used as control showed activity at
different ratios against the strains of all the bacteria and yeast. The results were compared
with standard drugs amoksilin for antibacterial activitiy and nystatin for antifungal
activity by measuring the zone of inhibition in mm at 1000 µg. Compound 2j was found
most effective of the synthesized compounds against S. aureus with zone of inhibition
23 mm, compound 1a is the most effective against P. aeruginosa and P. vulgaris with
zone of inhibition 16 mm, 2k is the most effective against K. pneumoniae and E. coli
with zone of inhibition 18 mm and 17 mm, respectively, and compound 1a is the most
effective among the synthesized compounds against B. megaterium with zone of
inhibition 27 mm. The compound 2j exhibited the maximum diameter of zone of
inhibition against C. albicans, C. glabrata and C. tropicalis (21 mm, 23 mm and 20 mm,
respectively). Compounds 1d, 1f, 1g, 1h, 1i, 2d and 2h showed no activity against the
strains of all the bacteria and the yeast used in the work. Although compounds 1a, 2f, 2g
and 2i showed an activity against most bacteria, they showed no activity against the yeast.
The results of the antibacterial and antifungal activity are given in Table 1.
Table 1. Antimicrobial and antifungal studies of synthesized compounds
Zone of inhibition/ mm
Compound numbers
Bacteria/Yeast
1a 1b 1c 1e 2a 2b 2c 2e 2f 2g 2i 2j 2k S*
D
13 10
16 15 10 10 12 15
16 15 11 13 13 11
-
-
13 13 13 10
9
9
-
12 10 23 19 38 10
S. aureus
9
14
9
14 10
9
10 28
8
8
8
9
9
P. aeruginosa
P. vulgaris
E. coli
9
-
-
9
9
13
10
10 14 30
-
-
12 10 10 11 15 10 13 10
15 11 10 11 13
27 13 10 10 13 15 12 10
-
17 34
18 25
9
-
9
9
9
-
-
-
K. pneumoniae
B. megaterium
C. albicans
C. glabrata
C. tropicalis
11 11 20 19 30
-
-
-
11 10 10 10
10 11 10
18 10 10 10
9
9
9
11 11
15 14
11 11
-
-
-
-
-
-
21 20 27
23 19 32 10
20 18 32
9
-
9
*Antiacterial Standard Drag: Amoksilin 1000 µg, Antifungal Standard Drag: Nystatin 1000 µg
D: DMSO

Antimicrobial Properties of Some Chalcones-Type Compounds
1578
Another striking result is to show more or less activity against all the bacteria and the
yeast of compounds 2a, 2b, 2c, 2e and 2k which are pyrazolines with hydroxyl group
moiety on the phenyl ring of their first four and the last is a pyrazoline having pyrrole
ring. Compound 1a possessing hydroxyl group on ortho position of phenyl ring has shown
very good antibacterial activity against B. megaterium and the activity is comparable with
that of the standard drug (amoksilin) (with 90% inhibition of that of the standard).
Compound 1a against other bacteria and compounds 1b, 2a, 2b, 2c, 2i and 2k against all
the bacteria showed moderate activity with 30-63% inhibition of that of the standard drug.
While compound 2j and 2k showed high antifungal activity against Candida albicans,
Candida glabrata and Candida tropicalis, with 56-78% inhibition of that of the standard
drug (nystatin), compounds 1c, 1e, 2a, 2b, 2c and 2e showed moderate activity against all
of the three yeast, with 28%-47% inhibition of that of the standard. The results obtained
for antibacterial and antifungal activities of 2-pyrazoline derivatives used in this study are
comparable with the values given in literature for some 2-pyrazolines23.
Spectral Analysis of Compounds
1-(Benzofuran-2-yl)-3-(furan-2-yl)-2-propenon (1j)
Yield: 77%; m.p.122-124 oC. FTIR (KBr, cm-1): 3000-3150 (=C-H stretching in furan), 1659
1
(C=O), 1597, 1563, 743; H-NMR (300 MHz, DMSO-d6), ppm : 7.71 (d, J= 7.3 Hz, 1H,
b4-H), 7.68 (d, J= 14.9 Hz, 1H, β-H), 7.62 (d, J= 1.8 Hz, 1H, f5-H), 7.61 (d, J= 8.5 Hz, 1H,
b7-H), 7.55 (s, 1H, b3-H), 7.47 (dt, J= 8.5 and 1.2 Hz, 1H, b6-H), 7.46 (d, J= 15.1 Hz, 1H,
α-H), 7.31 (t, J= 8.2 Hz, 1H, b-5H), 6.76 (d, J= 3.5 Hz, 1H, f3-H), 6.52 (dd, J= 3.4 and
1.8 Hz, 1H, f4-H). 13C-NMR, ppm : 178.6 (C=O), 155.7 (b8-C), 153.6 (b2-C), 151.4 (f2-C),
147.0 (f5-C), 130.4 (β-C), 129.0 (b6-C), 127.5 (b5-C) , 124.6 (b4-C), 124.2 (α-C), 121.1
(b9-C), 118.9 (b3-C), 118.3 (f3-C), 114.8 (b7-C), 112.7 (f4-C). Anal. Calcd. For C15H10O3:
C, 75.62; H, 4.23% Found C, 75.32; H, 4.27%.
1-(Benzofuran-2-yl)-3-(pyrrol-2-yl)-2-propenon (1k)
o
Yield: 50%; m.p.196-198 C. FTIR (KBr, cm-1): 3284 (N-H stretching), 1648 (C=O), 1579,
1550, 740 ;1H-NMR (300 MHz, DMSO-d6), ppm: 7.86-7.90 (m, 2H, b3, b4-H), 7.74 (dd, J= 8.3
and 0.8 Hz, 1H, b7-H), 7.68 (d, J= 15.7 Hz, 1H, β-H), 7.55 (dt, J= 7.8 and 1.2 Hz, 1H, b6-H), 7.5
(d, J= 15.5 Hz, 1H, α-H), 7.4 (dt, J= 7.5 and 0.8 Hz, 1H, b5-H), 7.19 (broad signal, 1H, pyrrole-5-
H), 6.81 (dd, J= 1.8 and 1.5 Hz, 1H, pyrrol-4-H), 6.27 (broad signal, 1H, pyrrole-3-H). Anal.
Calcd. For C15H11NO2: C, 75.94; H, 4.67; N, 5.90% Found C, 75.55; H, 4.70; N, 6.20%.
3-(Benzofuran-2-yl)-5-(2-dihydroxphenyl)-2-pyrazoline (2a)
Yield: 74%; m.p.210-212 oC. FTIR (KBr, cm-1) : 3437 (O-H), 3335 (N-H), ; 1H-NMR (300 MHz,
DMSO-d6), ppm: 9.64 (s, 1H, OH), 7.81 (d, J= 2.0 Hz, ,1H,NH), 7.56-7.63 (m, 2H, b4, b7-H),
7.32 (dt, J= 7.7 and 1.4 Hz, 1 H, b6-H), 7.25 (m, 2H, b5, 6-H), 7.09 (dt, J= 7.7 and 1.7 Hz, 1H,
4-H), 7.02 (s, 1H, b3-H), 6.85 (dd, J= 8.0 and 1.0 Hz, 1H, 3-H), 6.67 (ddd, J= 8.0 , 2.4 and 0.6 Hz,
1H, 3-H), 5.08 (dt, J= 10.3 and 1.9 Hz, 1H, p5-H), 3.45 (dd, J= 16.1 and 10.8 Hz, 1H, p4-H), 2.78
(dd, J= 16.1 and 9.7 Hz, 1H, p4-H). 13C-NMR, ppm : 155.1 (b8-C), 154.8 (2-C), 151.1 (p3-C),
140.6 (b2-C), 128.7 (6-C), 128.7 (1-C), 128.5 (b9-C), 126.9 (4-C), 125.3 (b6-C), 123.7 (b5-C),
121.6 (b4-C), 119.4 (5-C), 115.5 (3-C), 111.5 (b7-C), 105.4 (b3-C), 58.8 (p5-C), 39.5 (p4-C).
Anal. Calcd. For C17H14N2O2: C, 73.37; H, 5.07; N, 10.07% Found C, 73.75; H, 4.85; N, 9.88%.
3-(Benzofuran-2-yl)-5-(3-dihydroxphenyl)-2-pyrazoline (2b)
Yield: 80%; m.p.219-221 oC. FTIR (KBr, cm-1):3410 (O-H), 3335 (N-H); 1H-NMR
(300 MHz, DMSO-d6), ppm: 9.41 (s, 1H, OH), 7.85 (d, J= 2.0 Hz, 1H,NH), 7.57-7.64 (m, 2H,

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DEMET COŞKUN et al.
b4, b7-H), 7.35 (dt, J= 7.6 and 1.4 Hz, 1 H, b6-H), 7.25 (dt, J= 7.5 and 1.1 Hz, 1H, b5-H), 7.14
(t, J= 7.9 , 1H, 5-H), 7.02 (s, 1H, b3-H), 6.78-6.80 (m, 2H, 2,5-H), 6.67 (ddd, J= 8.0 , 2.4 and 0.6
Hz, 1H, 6-H), 4.83 (dt, J= 10.4 and 2.2 Hz, 1H, p5-H), 3.45 (dd, J= 16.1 and 10.8 Hz, 1H, p4-H),
2.86 (dd, J= 16.2 and 10.0 Hz, 1H, p4-H). 13C-NMR, ppm : 157.1 (3-C), 154.8 (b8-C), 151.0(p3-C),
144.6 (b2-C), 140.1 (1-C), 129.9 (5-C), 128.7 (b9-C), 125.4 (b6-C), 123.7 (b5-C), 121.6 (b4-C),
117.6 (6-C), 114.7 (2-C), 113.6 (4-C), 111.5 (b7-C), 105.4 (b3-C), 64.0(p5-C), 40.8(p4-C). Anal.
Calcd. For C17H14N2O2: C, 73.38; H, 5.04; N, 10.07% Found C, 73.82; H, 5.15; N, 9.97%.
3-(Benzofuran-2-yl)-5-(4-dihydroxphenyl)-2-pyrazoline (2c)
o
Yield: 76%; m.p.182-184 C. FTIR (KBr, cm-1) :3430 (O-H), 3358 (N-H), 1610, 808, 750;
1H-NMR (400 MHz, CDCl3), ppm: 7.56 (d, 1H, J= 8.5 Hz, b4-H), 7.51 (d,1H, J= 7.2, b7-H),
7.31 (dt, J= 8.2 and 1.3 Hz, 1H, b6-H), 7.20-7.24 (m,5H, b3,b5,NH,2-H), 6.78-6.84 (m, 3H,
OH, 3,5-H), 4.92 (dt, J= 9.6 and 1.8 Hz, 1H, p5-H), 3.45 (dd, J= 16.3 and 10.7 Hz, 1H,
p4-H), 3.05 (dd, J= 16.3 and 9.9 Hz, 1H, p4-H). Anal. Calcd. For C17H14N2O2: C, 73.38; H,
5.04; N, 10.07% Found C, 73.25; H, 5.12; N, 9.78%.
3-(Benzofuran-2-yl)-5-(4-N,N-dimethylaminophenyl)-2-pyrazoline (2d)
Yield: 78%; m.p.161-163 oC. FTIR (KBr, cm-1) :3343 (N-H), 1611, 829; 1H-NMR
(300 MHz, DMSO-d6), ppm: 7.83 (d, J= 2.3 Hz, ,1H,NH), 7.63 (d, J= 7.5 Hz , 1H,b4-H),
7.57 (d, J= 7.8 Hz, 1H, b7-H), 7.32 (dt, J= 7.8 and 1.5 Hz, 1 H, b6-H), 7.25 (dt, J= 7.5 and
1.1 Hz, 1H, b5-H), 7.18 (d, J= 8.7 , 2H, 2,6-H), 7.01 (s, 1H, b3-H), 6.70(d, J= 8.8 Hz, 2H,
3,5-H), 4.81 (dt, J= 10.5 and 2.3 Hz, 1H, p5-H), 3.38 (dt, J= 16.1 and 10.7 Hz, 1H, p4-H),
2.85 (dd, J= 16.3 and 10.5 Hz, 1H, p4-H). Anal. Calcd. For C19H19N3O: C, 74.73; H, 6.27;
N, 13.76% Found C, 75.05; H, 6.05; N, 13.90%.
3-(Benzofuran-2-yl)-5-(3-methoxy-4-dihydroxphenyl)-2-pyrazoline (2e)
o
Yield: 76%; m.p.123-125 C. FTIR (KBr, cm-1) :3526 (OH), 3227 (NH), 1595, 1524, 1258
1
(C-O-C), 751 ; H-NMR (400 MHz, CDCl3), ppm : 7.56 (d, 1H, J= 7.5 Hz, b4-H), 7.51
(d,1H, J= 7.6, b7-H), 7.40 (s, 1H, b3-H), 7.30 (t, J= 7.7 Hz, 1H, b6-H), 7.22 (t, J= 7.5 Hz,
1H, b5-H), 6.92(d, J= 1.6 Hz, 1H, NH), 6.82-6.88 (m, 4H,OH, 2,3,6-H), 4.92 (dt, J= 9.4 and
1.4 Hz, 1H, p5-H), 3.47 (dd, J= 16.3 and 10.8 Hz, 1H, p4-H), 3.06 (dd, J= 16.2 and 9.5 Hz,
1H, p4-H). Anal. Calcd. For C18H16N2O3: C, 70.12; H, 5.23; N, 9.09% Found C, 70.35; H,
5.08; N, 9.27%.
3-(Benzofuran-2-yl)-5-(3-nitrophenyl)-2-pyrazoline (2f)
o
Yield: 60%; m.p.125-127 C. FTIR (KBr, cm-1) :3348 (N-H), 1523 (NO2) , 1350 (NO2),
1H-NMR (400 MHz, CDCl3), ppm : 8.35 (s, 1H, 2-H), 8.15 (d, J= 8.6 Hz, 1H, 4-H),
7.60-7.75 (m, 2H, 5,6-H), 7.45-7.55 (m, 2H, b4,b7-H), 7.20-7.35 (m, 3H, b5,b6-H,NH), 7.05
(s, 1H, b3-H), 5.20 (t, J= 10.1 Hz, 1H, p5-H), 3.52 (dd, J= 16.8 and 10.0 Hz, 1H, p4-H), 3.05
(dd, J=16.8 and 10.0 Hz, 1H, p4-H). Anal. Calcd. For C17H13N3O3: C, 66.44; H, 4.26; N,
13.67% Found C, 67.01; H, 4.15; N, 14.20%.
3-(Benzofuran-2-yl)-5-phenyl-2-pyrazoline (2g)
o
Yield: 81%; m.p.113-115 C, FTIR (KBr, cm-1) :3347 (N-H), 3100-3000, 1610, 1587, 747,
1
698; H-NMR (300 MHz, DMSO-d6), ppm: 8.01 (d, J= 2.6 Hz, 1H, p-NH), 7.58-7.65
(m, 2H, b4,b7-H), 7.22-7.40 (m, 7H, 2-6,b5,b6-H), 7.02 (s, 1H, b3-H), 4.92 (dt, J= 10.7 and
2.6 Hz, 1H, p5-H), 3.48 (dd, J= 16.1 and 10.4 Hz, 1H, p4-H), 2.90 (dd, J= 16.1 and 10.9 Hz,
1H, p4-H). Anal. Calcd. For C17H14N2O: C, 77.84; H, 5.38; N, 10.68% Found C, 78.22; H,
5.25; N, 10.98%.

Antimicrobial Properties of Some Chalcones-Type Compounds
1580
1,4-Bis[3-(benzofuran-2-yl)-2-pyrazoline-5-yl] benzene (2h).
Yield: 45%; m.p.254-256 oC. FTIR (KBr, cm-1): 1H-NMR (300 MHz,DMSO-d6), ppm: 7.99
(broad, 2H, p-NH), 7.62 (d, J= 7.2 Hz, 2H, b4-H), 7.58 (d, J= 7.8 Hz, 2H, b7-H), 7.38
(s, 4H, 2,3,5,6-H), 7.32 (t, J= 8.6 Hz,1H, b6-H), 7.29 (t, J= 7.5 Hz,1H, b5-H), 7,02 (s, 2H,
b3-H), 4.92 (broad, t, J= 10.2 Hz, 2H, p5-H), 3.47 (dd, J= 16.2 and 10.9 Hz, 2H, p4-H), 2.89
(dd, J= 16.1 and 10.4 Hz, 2H, p4-H). Anal. Calcd. For C28H22N4O2: C, 75.34; H, 4.93; N,
12.56% Found C, 76.12; H, 5.20; N, 11.96%.
3-(Benzofuran-2-yl)-5-(thiophene-2-yl)-2-pyrazoline (2i)
Yield: 90%; m.p.114-116 oC. FTIR (KBr, cm-1): 3296 (N-H), 1601, 808, 750, 700; 1H-NMR
(300 MHz, DMSO-d6), ppm: 8.09 (d, J= 2.5 Hz, 1H, NH), 7.58-7.66 (m, 2H, b4,b7-H), 7.44
(dd, J= 5.0 and 1.1 Hz, 1H, t3-H), 7.34 (dt, J= 7.5 Hz and 1.0 Hz, 1H, b5-H), 7.26 (dt,
J= 7.3 Hz and 1.4 Hz, 1H, b6-H), 7.08-7.10 (m, 2H, t5,b3-H), 7.00 (dd, J= 5.1 and 3.47 Hz,
1H, t4-H), 5.18 (dt, J= 10.3 and 2.5 Hz, 1H, p5-H), 3.49 (dd, J= 16.1 and 10.6 Hz), 2.95 (dd,
J= 16.1 and 10.2 Hz). 13C-NMR, ppm : 154.9 (b8-C), 150.6 (p3-C), 146.4 (b2-C), 141.0 (t2-C),
128.6 (b9-C), 127.3 (t4-C), 125.5 (t3-C), 125.4 (b6-C), 125.3 (t5-C), 123.7 (b5-C), 121.7 (b4-
C), 111.6 (b7-C), 105.9 (b3-C), 59.8 (p5-C), 41.5 (p4-C). Anal. Calcd. For C15H12N2OS: C,
67.16; H, 4.48; N, 10.45; S, 11.94% Found C, 67.23; H, 4.32; N, 10.63; S, 11.76%.
3-(Benzofuran-2-yl)-5-(furan-2-yl)-2-pyrazoline (2j)
o
Yield: 77%; m.p.92-94 C. FTIR (KBr, cm-1): 3318, 3150-3000, 1605, 1258, 1154, 747;
1H-NMR (400 MHz, CDCl3), ppm: 7.91 (d,J= 2.1 Hz, 1H, NH), 7.57-7.67 (m, 3H, b4,b7,
f5-H), 7.33 (dt, J= 8.3 and 1.4 Hz, 1H, b5-H), 7.26 (dt, J= 7.3 and 1.1 Hz, 1H, b6-H), 7.07
(s, 1H, b3-H), 6.38-6.43(m, 2H, f3,f4-H), 4.95 (dt, J= 10.1 and 2.1 Hz, 1H, p5-H), 3.37 (dd,
J= 15.6 and 11.5 Hz, 1H, p4-H), 3.14 (dd, J= 16.2 and 9.2 Hz, p4-H). Anal. Calcd. For
C15H12N2O2: C, 71.43; H, 4.76; N, 11.11% Found C, 71.27; H, 4.55; N, 11.04%.
3-(Benzofuran-2-yl)-5-(pyrrol-2-yl)-2-pyrazoline (2k)
1
Yield: 93%; m.p.175-177 oC. FTIR (KBr, cm-1): 3312, 3190, 3130, 1610, 1541; H-NMR
(400 MHz, CDCl3), ppm: 11.81 (broad, 1H, NH), 8.50 (broad, 1H, pyrrole-NH), 7.56
(d, J= 8.7 Hz, 1H, b4-H), 7.53 (d, J= 8.6 Hz, 1H, b7-H), 7.32 (t, J= 8.5 Hz, 1H, b6-H), 7.24
(t, J= 8.6 Hz, 1H, b5-H), 6.82 (s, 1H, b3-H), 6.76 (m, 1H, pyrrole-5-H), 6.13-6.17 (m, 3H,
p-NH, pyrrole-3,4-H), 5.05 (t, J= 10.2 Hz, 1H, p5-H), 3.41 (dd, J= 16.3 and 10.3 Hz, 1H,
p4-H), 3.09 (dd, J= 16.30and 10.1 Hz, 1H, p4-H). Anal. Calcd. For C15H13N3O: C, 71.71; H,
5.18; N, 16.73% Found C, 71.52; H, 5.20; N, 17.02%.
Conclusion
Syntheses and structural characterizations of two new chalcones and eleven pyrazolines were
given in this study. The cyclization of the chalcones, given 2-pyrazoline was carried out at a
shorter period of time than that of the some other chalcones given in literature using absolute
ethanol in reflux. Antibacterial and antifungal activities of twenty compounds from this new class
of benzofurane chalcones and pyrazoline derivatives against the six bacteria and three yeast were
investigated. Seven compounds (1d, 1f, 1g, 1h, 1i, 2d and 2h) showed no activity against any
bacteria and any yeast. Five compounds (2a, 2b, 2c, 2e and 2k) which are the all pyrazoline
derivatives have exhibited an activity against all of the bacteria and yeast. Compound 1a
possessing hydroxyl group on ortho position of phenyl ring has exhibited a comparable
antibacterial activity against B. megaterium with that of the standard drug (amoksilin). While the
compounds 1b, 1c, 1e and 2j are effective against most of bacteria and yeast used in this work,
the compounds 2f, 2g and 2i are effective against most bacteria but no yeast.

1581
DEMET COŞKUN et al.
Acknowledgment
The authors thank Firat University (FUBAP-1305) for financial support of this project.
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