3-(Substituted aryl)-1-(benzofuran-2-yl)-2-propenones, part 1: Synthesis and characterization of some novel chalcones

Article abstract of DOI:10.1080/00397910802178997

Synthesis and characterization of some novel chalcones by condensation of 2-acetylbenzofurane and various aromatic aldehydes is described. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910802178997

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3-(Substituted Aryl)-1-
(benzofuran-2-yl)-2-
propenones, Part 1: Synthesis
and Characterization of Some
Novel Chalcones
Demet Coşkun a & Misir Ahmedzade a
a Department of Chemistry , Faculty of Science and
Arts, University of Firat , Turkey
Published online: 14 Oct 2008.
To cite this article: Demet Coşkun & Misir Ahmedzade (2008) 3-(Substituted
Aryl)-1-(benzofuran-2-yl)-2-propenones, Part 1: Synthesis and Characterization
of Some Novel Chalcones, Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic Chemistry, 38:21, 3613-3622, DOI:
10.1080/00397910802178997
To link to this article: http://dx.doi.org/10.1080/00397910802178997
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Synthetic Communications1, 38: 3613–3622, 2008
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910802178997
3-(Substituted Aryl)-1-(benzofuran-2-yl)-
2-propenones, Part 1: Synthesis and
Characterization of Some Novel Chalcones
Demet Cos¸kun and Misir Ahmedzade
Department of Chemistry, Faculty of Science and Arts,
University of Firat, Turkey
Abstract: Synthesis and characterization of some novel chalcones by conden-
sation of 2-acetylbenzofurane and various aromatic aldehydes is described.
Keywords: Aromatic aldehydes, benzofuranes, chalcones
INTRODUCTION
A chalcone group as a classical photosensitive unit has been well studied
and used in photocrosslinkable polymers because it affords high sensitiv-
ity to UV radiation and chemical resistance of the resultant polymers.[1]
Chalcone derivatives are materials noted for their excellent blue-light
transmittance and good crystallizability, and chalcones provide a neces-
sary configuration to show nonlinear optical property with planar rings
connected through a conjugated double bond.[2,3] Many studies have
been reported on the biological activity of chalcone derivatives.[4–7]
The most widely used of the many methods available for synthesis of
chalcones is the base-catalyzed Claisen–Schmidt reaction in which the
condensation of a ketone with an aldehyde is carried out in the presence
of potassium hydroxide,[8] sodium hydroxide,[9–11] barium hydroxide,[12]
Received April 2, 2008.
Address correspondence to Demet Cos¸kun, Department of Chemistry,
Faculty of Science and Arts, University of Firat, 23119 Elazig˘, Turkey. E-mail:
dcoskun@firat.edu.tr
3613

3614
D. Cos¸kun and M. Ahmedzade
Scheme 1. Scheme of chalcones.
and LiHDMS.[13] Some methods for the synthesis of chalcones include
the use of a Lewis acid such as BF3-Et2O,[14] TiCl4,[15] or RuCl3.[16]
We have synthesized some novel chalcones 3a–m by condensation of
2-acetylbenzofurane and various aromatic aldehydes.
RESULTS AND DISCUSSION
This work is a part of the studies done on 3-(substituted aryl)-1-benzofur-
anyl-2-propenones and describes the synthesis and characterization
of some new chalcones by condensation of 2-acetylbenzofurane and
13 aromatic aldehydes. These aldehydes are 2-hydroxybenzaldehyde 2a,
3-hydroxybenzaldehyde 2b, 4-hydroxybenzaldehyde 2c, 4-(dimethylami-
no)benzaldehyde 2d, 2-fluorobenzaldehyde 2e, 3-fluorobenzaldehyde 2f,
3-hydroxy-2-methoxybenzaldehyde 2g, benzene-1,4-dicarboxaldehyde
(terephthalaldehyde) 2h (monofunctional), 2-nitrobenzaldehyde 2i, benz-
aldehyde 2j, 5-bromosalicylaldehyde 2k, thiophene-2-carboxaldehyde 2l,
and benzene-1,4-dicarboxaldehyde 2m (difunctional) (Scheme 1).
For the synthesis of chalcones, the most common route is the base-
catalyzed Claisen–Schmidt reaction involving condensation of a benzal-
dehyde derivative with an acetophenone derivative in ethanol with
sodium hydroxide catalyst[9–11] (method A). Another route is a new
described methodology based on the Claisen–Schmidt reaction in the pre-
sence of BF3-Et2O[14] (method B). Although method B was used in pre-
paring chalcones 3c, h, and g, the synthesis of chalcone derivatives 3a,
b, d–f, and i–m was carried out according to procedures in method A.

3-(Substituted Aryl)-1-(benzofuran-2-yl)-2-propenones
3615
Scheme 2. Acylation of 3c.
All the chalcones, except 3h and i, were purified by recrystallization from
ethanol. Chalcones 3h and i were crystallized from a mixture of N,N-
dimethylformamide (DMF) and ethanol (1:3, v:v). The acylation of 3c
with bromoacetyl bromide and methacryloyl chloride gave 4c and 5c,
respectively (Scheme 2). Chalcone derivative 4c can be used as an initia-
tor of atom transfer radical polymerization (ATRP)[17] and gives a poly-
mer with a chalcone end group. Chalcone derivative 5c is a methacrylate
monomer with a chalcone side group, and it can be used in synthesis of
polymers with a chalcone side group. Our research group continues to
study the syntheses of the polymers involving chalcone.
1
All new compounds were characterized by H NMR, Fourier trans-
form infrared (FTIR), elemental analysis, and (for some compounds) 13
C
NMR. Although the starting material 2-acetylbenzofurane showed a car-
bonyl stretching vibration at 1675 cmꢀ1 in the FTIR spectrum, the chal-
cones showed the characteristic bands between 1639 and 1662 cmꢀ1
(C¼O stretching in chalcone) and between 1605 and 1615 cmꢀ1 (C¼C
stretching in chalcone) in wave numbers changing according to chalcone
structure. The most characteristic signals in 1H NMR spectra of the chal-
cones were observed at 8.08–8.43 ppm (3b-H in benzofurane of chalcone)
and at 7.60–8.00 ppm (a- and b-H of chalcone, resonance of b-H is at a
lower field than that of a-H) with a coupling constant about 15 Hz, which
characterizes the trans-configuration.
EXPERIMENTAL
Melting points were measured using a differential scanning calorimeter
(Shimadzu DSC-50) and are uncorrected. Elemental analyses were
performed on a Leco CHNS-932 apparatus. 1H NMR spectra were deter-
mined on a Bruker AC 300 (300-MHz) spectrometer, with tetramethylsi-
lane (TMS) as the internal standard in the solvents shown, and 13C NMR
spectra were recorded on a Bruker (75.47-MHz) spectrometer. Infrared
(IR) spectra were recorded as KBr pellets on a Perkin-Elmer Spectrum
One FTIR spectrometer.

3616
D. Cos¸kun and M. Ahmedzade
Preparation of Chalcones
Method A
A solution of 2-acetylbenzofurane 1 (2.24 g, 14.0 mmol) and the aldehyde
2a, b, d–f, and i–k (14.0 mmol) in methanol (25 mL) was cooled to 0–5 ꢁC,
and then 18 mL of aqueous NaOH (1 mol=L) was added to this solution
and stirred at room temperature for 3 h. The solution was allowed to
stand in the refrigerator overnight. The solid precipitated upon the addi-
tion of water, was filtered after neutralization with diluted HCl, and was
washed several times with water. The solid was recrystallized from an
appropriate solvent to provide the chalcone.
Method B
This method was adapted from the literature.[14] To a stirred solution of
2-acetylbenzofurane 1 (4.0 g, 25 mmol) and the aldehyde 2c, h, and g
(25 mmol) in a little dry dioxane, BF3-Et2O (1.5 mL, 12.5 mmol) was added
gradually at room temperature. The solution was stirred for 5 h at 35 ꢁC.
The solid product was precipitated by addition to excess water of the
solution, and the precipitate was filtered off. The product was washed a
few times with ether and dried in a vacuum oven at 50 ꢁC for 24 h.
Data
3-(2-Hydroxyphenyl)-1-(benzofurane-2-yl)-2-propen-1-one (3a)
Compound 3a was synthesized according to method A and crystallized
from ethanol. Yield: 2.03 g, 55%; mp193 ꢁC; FTIR (KBr, cmꢀ1): 3236,
3000–3100, 1639, 1614, 1602, 1575, 1250, 1141, 947, 764, 750; 1H
NMR (300 MHz, CDCl3): d 9.03 (s, 1H, OH), 8.08 (d, J ¼ 8.37 Hz, 1H,
b4-H), 7.72 (d, J ¼ 7.20 Hz, 1H, b7-H), 7.22–7.68 (m, 9H, all the others);
13C NMR: d 179.68 (C ¼ O), 155.90 (b8-C), 155.62 (b2-C), 152.53 (2-C),
141.91 (b-C), 132.01 (b9-C), 110.48–128.11 (the other Cs). Anal. calcd.
for C17H12O3: C, 77.29; H, 4.54. Found: C, 77.43; H, 4.35.
3-(3-Hydroxyphenyl)-1-(benzofurane-2-yl)-2-propen-1-one (3b)
Compound 3b was synthesized according to method A and crystallized
from ethanol. Yield: 2.15 g, 58%; mp 176 ꢁC; FTIR (KBr, cmꢀ1): 3226,

3-(Substituted Aryl)-1-(benzofuran-2-yl)-2-propenones
3617
1
3000–3100, 1639, 1646, 1612, 1582, 1229, 1145, 973, 853, 785, 679; H
NMR (300 MHz, DMSO-d6): d 9.70 (broad, OH), 8.31 (s, 1H, b3-H),
7.87 (d, J ¼ 7.76 Hz, 1H, b4-H), 7.82 (d, J ¼ 15.69 Hz, 1H, b-H), 7.76
(d, J ¼ 7.90 Hz, 1H, b7-H), 7.75 (d, J ¼ 15.72 Hz, 1H, a-H), 7.57 (dd,
J ¼ 7.80 Hz and 7.36 Hz, 1H, b6-H), 7.40 (dd, J ¼ 7.75 Hz and 7.40 Hz,
1H, b5-H), 6.91 (d, J ¼ 7.20 Hz, 1H, 4-H), 7.27–7.33 (m, 3H, 2,5, 6-H).
Anal. calcd. for C17H12O3: C, 77.29; H, 4.54. Found: C, 77.54; H, 4.54.
3-(4-Hydroxyphenyl)-1-(benzofurane-2-yl)-2-propen-1-one (3c)
Compound 3c was synthesized according to method B and purified by
washing with hot ethanol. Yield: 3.10 g, 47%; mp 254 ꢁC; FTIR (KBr,
cmꢀ1): 3246, 3000–3100, 1643, 1609, 1575, 1547, 1516, 1285, 1164, 979,
829, 759; 1H NMR (300 MHz, DMSO-d6): d 10.17 (s,1H, OH), 8.21
(s, 1H, b3-H), 7.86 (d, J ¼ 7.70 Hz, 1H, b4-H), 7.70–7.80 (m, 4H, 2, 6,
b7, b-H), 7.67 (d, J ¼ 15.10 Hz, 1H, a-H), 7.54 (dd, J ¼ 7.75 Hz and
7.50 Hz, 1H, b6-H), 7.38 (dd, J ¼ 7.57 and 7.47 Hz, 1H, b5-H), 6.89 (d,
J ¼ 6.60 H, 2H, 3, 5-H); 13C NMR: d 178.94 (C¼O), 160.91 (b8-C),
155.66 (4-C), 154.00 (b2-C), 144.48 (b-C), 132.58 (b9-C), 131.67 (2,
6-C), 127.84 (1-C), 127.54 (b6-C), 125.97 (b5-C), 124.50 (a-C), 124.10
(b4-C), 118.76 (b3-C), 116.39 (3,5-C), 112.70 (b7-C). Anal. calcd. for
C17H12O3: C, 77.29; H, 4.54. Found: C, 77.28; H, 4.40.
3-(4-N,N-dimethylaminophenyl)-1-(benzofurane-2-yl)-
2-propen-1-one (3d)
Compound 3d was synthesized according to method A and crystallized
from ethanol. Yield: 3.26 g, 80%; mp 150 ꢁC; FTIR (KBr, cmꢀ1):
3000–3100, 1643, 1611, 1569, 1544, 1522, 1375, 1359, 1267, 1152,
1
804, 746; H NMR (300 MHz, DMSO-d6): d 8.16 (s, 1H, b3-H), 7.86
(d, J ¼ 7.74 Hz, 1H, b4-C), 7.76 (d, J ¼ 15.50 Hz, 1H, b-H), 7.75 (d, J ¼
6.80 Hz, 1H, b7-H), 7.73 (d, J ¼ 8.83 Hz, 2H, 2, 6-H), 7.60 (d,
J ¼ 15.51 Hz, 1H, a-H), 7.54 (dd, J ¼ 7.80 and 7.03 Hz, 1H, b6-H), 7.39
(dd, J ¼ 7.55 and 7.20 Hz, 1H, b5-H), 6.78 (d, J ¼ 8.91 Hz, 2H, 3, 5-H),
3.03 (s, 6H, N,N-dimethyl). Anal. calcd. for C19H17O2N: C, 78.37; H,
5.84; N, 4.81. Found: C, 77.93; H, 5.56; N, 4.42.
3-(2-Fluorophenyl)-1-(benzofurane-2-yl)-2-propen-1-one (3e)
Compound 3e was synthesized according to method A and crystallized
from ethanol. Yield: 2.02 g, 54%; mp 100 ꢁC; FTIR (KBr, cmꢀ1): 3120,

3618
D. Cos¸kun and M. Ahmedzade
3067, 1659, 1611, 1576, 1550, 1292, 1160, 753; 1H-NMR (300 MHz,
DMSO-d6): d 8.30 (s, 1H, b3-H), 8.11 (dd, J ¼ 7.60 and 7.20 Hz, 1H,
b6-H), 7.93 (d, J ¼ 15.87 Hz, 1H, b-H), 7.90 (dd, J ¼ 8.37 and 7.55 Hz,
1H, b5-H), 7.89 (d, J ¼ 15.87 Hz, 1H, a-H), 7.76 (d, J ¼ 8.41 Hz, 1H,
b4-H), 7.29–7.61 (m, 5 H, b7, 3, 4, 5, 6-H). Anal. calcd. for
C17H11O2F: C, 76.71; H, 4.13. Found: C, 76.45; H, 4.05.
3-(3-Fluorophenyl)-1-(benzofurane-2-yl)-2-propen-1-one (3f)
Compound 3f was synthesized according to method A and crystallized
from ethanol. Yield: 1.75 g, 47%; mp 99 ꢁC; FTIR (KBr, cmꢀ1): 3118,
3073, 1662, 1611, 1582, 1545, 1278, 1156, 981, 850, 753; 1H NMR
(300 MHz, DMSO-d6): d 8.39 (s, 1H, b3-H), 7.97 (d, J ¼ 15.60 Hz, 1H,
b-H), 7.70–7.90 (m, 3H, b4, b6, a-H), 7.35–7.63 (m, 6 H, b5, b6, 2, 4,
5, 6-H). Anal. calcd. for C17H11O2F: C, 76.71; H, 4.13. Found: C,
76.57; H, 4.18.
3-(3-Methoxy-4-hydroxyphenyl)-1-(benzofurane-2-yl)-
2-propen-1-one (3g)
Compound 3g was synthesized according to method B and crystallized
from ethanol. Yield: 3.67 g, 50%; mp177 ꢁC; FTIR (KBr, cmꢀ1): 3250,
3000–3100, 1653, 1611, 1580, 1570, 1272, 1239, 1163, 112, 978, 807,
1
758; H NMR (300 MHz, DMSO-d6): d 9.82 (broad, 1H, OH), 8.25 (s,
1H, b3-H), 7.88 (d, J ¼ 7.60 Hz, 1H, b4-H), 7.78 (d, J ¼ 15.60 Hz, 1H,
b-H), 7.70 (d, J ¼ 15.80 Hz, 1H, a-H), 7.60 (d, J ¼ 7.50 Hz, 1H, b7-H),
7.54 (dd, J ¼ 7.57 and 7.48, 1H, b6-H), 7.53 (s, 1H, 2-H), 7.39 (t,
J ¼ 7.60 Hz, 1H, b5-H), 7.33 (dd, J ¼ 8.10 and 1.8 Hz, 1H, 6-H), 6.87
(d, J ¼ 8.14 Hz, 1H, 5-H), 3.90 (s, 3H, CH3). Anal. calcd. for
C18H14O4: C, 77.27; H, 4.55. Found: C, 76.95; H, 4.35.
3-(4-Methanoylphenyl)-1-(benzofurane-2-yl)-2-propen-1-one (3h)
Compound 3h was synthesized according to method B and crystallized
from a mixture of N,N-dimethylformamide (DMF) and ethanol (1:3,
v:v). Yield: 2.76 g, 40%; mp164 ꢁC; FTIR (KBr, cmꢀ1): 3000–3115,
1
2848, 2752, 1695, 1662, 1609, 1568, 1548, 1171, 1042, 979, 816, 744; H
NMR (300 MHz, DMSO-d6): d 10.07 (s, 1H, CHO), 8.40 (s, 1H, b3-
H), 8.13 (d, J ¼ 8.22 Hz, 2H, 3, 5-H), 8.04 (d, J ¼ 15.6 Hz, 1H, b-H),
8.01 (d, J ¼ 8.27 Hz, 2H, 2, 6-H), 7.92 (d, J ¼ 7.53, 1H, b4-H), 7.89 (d,
J ¼ 15.60 Hz, 1H, a-H), 7.77 (d, J ¼ 8.41 Hz, 1H, b7-H), 7.59 (dd,

3-(Substituted Aryl)-1-(benzofuran-2-yl)-2-propenones
3619
J ¼ 8.30 and 7.30 Hz, 1H, b6-H), 7.43 (dd, J ¼ 7.53 and 7.50 Hz, 1H,
b5-H). Anal. calcd. for C18H12O3: C, 78.28; H, 4.35. Found: C, 79.03;
H, 4.28.
3-(3-Nitrophenyl)-1-(benzofurane-2-yl)-2-propen-1-one (3i)
Compound 3i was synthesized according to method A and crystallized
from a mixture of DMF and ethanol (1:3, v:v). Yield: 2.13 g, 52%;
mp 189 ꢁC; FTIR (KBr, cmꢀ1): 3000–3120, 1669, 1615, 1549, 1521,
1
1358, 1282, 1165, 1040, 976, 812, 740; H NMR (300 MHz, DMSO-d6):
d 8.79 (s, 1H, 2-H), 8.43 (s, 1H, b3-H), 8.33 (d, J ¼ 7.74 Hz, 1H, 4-H),
8.27 (dd, J ¼ 7.41 and 1.52 Hz, 1H, 6-H), 8.08 (d, J ¼ 15.77 Hz, 1H,
b-H), 7.92 (d, J ¼ 15.90 Hz, 1H, a-H), 7.90 (d, J ¼ 7.50 Hz, 1H, b4-H),
7.74–7.79 (m, 2H, 5, b7-H), 7.58 (dd, J ¼ 7.60 and 7.62 Hz, 1H, b6-H),
7.40 (dd, J ¼ 7.51 and 7.48 Hz, 1H, b5-H). Anal. calcd. for C17H11O4N:
C, 69.64; H, 3.75; N, 4.78. Found: C, 70.03; H, 3.59; N, 4.65.
3-Phenyl-1-(benzofurane-2-yl)-2-propen-1-one (3j)
Compound 3j was synthesized according to method A and crystallized
from ethanol. Yield: 2.60 g, 75%; mp 121 ꢁC; FTIR (KBr, cmꢀ1): 3000–
1
3100, 1657, 1605, 1595, 1575, 1553, 1159, 1138, 1044, 937, 752, 681; H
NMR (300 MHz, DMSO-d6): d 8.34 (s, 1H, b3-H), 7.88–7.96 (m, 4H,
2, b, b4-H), 7.83 (d, J ¼ 15.6 Hz, 1H, a-H), 7.77 (dd, J ¼ 7.40 and
1.0 Hz, 1H, b7-H), 7.58 (dt, J ¼ 7.20 and 1.2 Hz, 1H, b6-H), 7.46–7.52
(m, 3H, 3, b5-H), 7.40 (dt, J ¼ 7.50 and 1.0 Hz, 1H, 4-H). Anal. calcd.
for C17H12O2: C, 82.26; H, 4.84. Found: C, 81.35; H, 5.58.
3-(2-Hydroxy-5-bromophenyl)-1-(benzofurane-2-yl)-2-propen-1-one (3k)
Compound 3k was synthesized according to method A and crystallized
from ethanol. Yield: 1.92 g, 40%; mp 208 ꢁC; FTIR (KBr, cmꢀ1): 3200,
1
3000–3100, 1646, 1615, 1594, 1546, 1294, 1163, 1050, 981, 819, 738; H
NMR (300 MHz, DMSO-d6): d 10.69 (s, broad, 1H, OH), 8.34 (s, 1H,
b3-H), 8.16 (d, J ¼ 2.44 Hz, 1H, 6-H), 8.03 (d, J ¼ 15.87 Hz, 1H, b-H),
7.92 (d, J ¼ 15.94 Hz, 1H, a-H), 7.89 (d, J ¼ 7.40 Hz, 1H, b4-H), 7.76
(d, J ¼ 8.40 Hz, 1H, b7-H), 7.58 (dd, J ¼ 8.32 and 7.26 Hz, 1H, b6-H),
7.44 (dd, J ¼ 8.54 and 2.45 Hz, 1H, b5-H), 7.41 (dd, J ¼ 7.50 and
7.20 Hz), 6.92 (d, J ¼ 8.74 Hz, 1H, 6-H). Anal. calcd. for C17H11O3Br: C,
59.48; H, 3.21. Found: C, 61.25; H, 3.70.

3620
D. Cos¸kun and M. Ahmedzade
3-(Thiophene-2-yl)-1-(benzofurane-2-yl)-2-propen-1-one (3l)
Compound 3l was synthesized according to method A and crystallized
from ethanol. Yield: 2.52 g, 71%; mp 140 ꢁC; FTIR (KBr, cmꢀ1): 300–
3100, 1656, 1592, 1557, 1292, 1157, 1139, 995, 937, 823, 744, 707, 603;
1H NMR (300 MHz, DMSO-d6): d 8.21 (s, 1H, b3-H), 8.01 (d,
J ¼ 15.40 Hz, 1H, b-H), 7.86 (d, J ¼ 7.51 Hz, 1H, b4-H), 7.83 (d,
J ¼ 5.14 Hz, 1H, 3-H), 7.75 (dd, J ¼ 8.40 and 0.74 Hz, 1H, b7-H), 7.72
(d, J ¼ 3.56 Hz, 1H, 5-H), 7.56 (ddd, J ¼ 8.32, 7.35, and 1.11 Hz, 1H,
b6-H), 7.52 (d, J ¼ 15.42 Hz, 1H, a-H), 7.39 (dt, J ¼ 7.52 and 0.74 Hz),
7.22 (dd, J ¼ 5.01 and 3.67 Hz, 1H, 4-H). Anal. calcd. for C19H17O2N: C,
70.86; H, 3.93; S, 12.62. Found: C, 71.28; H, 4.06; S, 12.18.
Benzene-1,4-bis[1-(2-benzofuranyl)-3-propenyl-1-one] (3m)
Compound 3m was synthesized according to method A using 28 mmol of
2-acetylbenzofurane and 36 mL of aqueous NaOH (1 mol=L) per 14 mmol
of benzene-1,4-dicarboxaldehyde 2h and purified by washing with water,
a mixture of DMF and ethanol (3:1, v:v), and chlorform, respectively.
Yield: 6.44 g, 55%; mp 286 ꢁC; FTIR (KBr, cmꢀ1): 3106, 3055, 1661,
1
1608, 1544, 1182, 1048, 981, 821, 732; H NMR (300 MHz, DMSO-d6):
d 8.40 (s, 2H, b3-H), 8.06 (s, 4H, 2, 3, 5, 6-H), 8.02 (d, J ¼ 15.23 Hz,
2H, b-H), 7.93 (d, J ¼ 8.17 Hz, 2H, b4-H), 7.88 (d, J ¼ 15.70 Hz, 2H,
a-H),7.79 (d, J ¼ 8.10 Hz, 2H, b7-H), 7.59 (dd, J ¼ 7.65 and 7.45 Hz,
2H, b6-H), 7.43 (dd, J ¼ 7.65 and 7.32 Hz, 2H, b5-H). Anal. calcd. for
C28H18O4: C, 80.38; H, 4.31; Found: C, 81.28; H, 4.05.
3-[4-(a-Bromoacetoxy)phenyl]-2-(benzofurane-2-yl)-2-propen-1-one (4c)
Compound 3c (0.70 g, 2.65 mmol) was dissolved in 15 mL of dry THF,
and triethylamine (0.39 mL, 2.70 mmol) was added. a-Bromoacetyl bro-
mide (0.55 g, 2.70 mmol) was added dropwise to the mixture and cooled
to 0 ꢁC. After stirring overnight at room temperature, water (50 mL) was
added, and the precipitate was crystallized from ethanol. Yield: 0.36 g,
35%; mp 130 ꢁC; FTIR (KBr, cmꢀ1): 3000–3114, 1763, 1663, 1609,
1584, 1550, 1505, 1166, 1135, 982, 833, 756; 1H NMR (300 MHz,
DMSO-d6): d 8.33 (s, 1H, b3-H), 8.01 (d, J ¼ 8.66 Hz, 2H, 2, 6-H), 7.90
(d, J ¼ 15.67 Hz, 1H, b-H), 7.87 (d, J ¼ 7.70 Hz, 1H, b4-H), 7.84
(d, J ¼ 15.90 Hz, 1H, a-H), 7.76 (d, J ¼ 8.30 Hz, 1H, b7-H), 7.58 (dd,
J ¼ 8.10 and 7.20 Hz, 1H, b6-H), 7.40 (dd, J ¼ 7.51 and 7.49 Hz, 1H,
b5-H), 7.31 (d, J ¼ 8.62 Hz, 2H, 3,5-H), 4.49 (s, 2H, CH2Br). Anal. calcd.
for C19H13O4Br: C, 59.22; H, 3.38; Found: C, 60.08; H, 3.55.

3-(Substituted Aryl)-1-(benzofuran-2-yl)-2-propenones
3621
3-(4-Methacryloyloxyphenyl)-1-(benzofurane-2-yl)-2-propen-1-one (5c)
Compound 3c (0.60 g, 2.27 mmol) was dissolved in 15 mL of dry THF, and
triethylamine (0.4 mL, 2.79 mmol) was added. Methacryloyl chloride
(0.29 g, 2.79 mmol) was added dropwise to the mixture cooled to 0 ꢁC.
After stirring overnight at room temperature water (50 mL) was added,
and the precipitate was crystallized from ethanol. Yield: 0.38 g, 51%;
mp 160 ꢁC; FTIR (KBr, cmꢀ1): 3000–3119, 1725, 1659, 1607, 1597,
1548, 1341, 1212, 1167, 978, 880, 809, 745; 1H NMR (300 MHz,
DMSO-d6): d 8.32 (s, 1H, b3-H), 7.98 (d, J ¼ 8.61 Hz, 2H, 2,6-H), 7.91
(d, J ¼ 15.72 Hz, 1H, b-H), 7.88 (d, J ¼ 7.90 Hz, 1H, b4-H), 7.83 (d,
J ¼ 15.76 Hz, 1H, a-H), 7.78 (d, J ¼ 8.55 Hz, 1H, b7-H), 7.57 (dd,
J ¼ 8.41 and 7.18 Hz, 1H, b6-H), 7.40 (dd, J ¼ 7.54 and 7.51 Hz, 1H,
b5-H), 7.32 (d, J ¼ 8.57 Hz, 2H, 3, 5-H), 6.31 (d, J ¼ 1.2 Hz, 1H, ¼C-H,
trans to methyl), 5.93 (d, J ¼ 1.2 Hz, ¼ C-H, cis to methyl), 2.02 (s, 3H,
CH3). Anal. calcd. for C21H16O4: C, 75.90; H, 4.82. Found: C, 76.25;
H, 4.75.
ACKNOWLEDGMENT
The authors thank Firat University (FUBAP-1305) for financial support
of this project.
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