Synthesis of 3-aryl-2-benzoylbenzofuran derivatives using manganese(III) acetate-mediated addition of dimedon to chalcone derivatives

Article abstract of DOI:10.1080/00397910701862782

3-Aryl-2-benzoylbenzofurans were synthesized by the reaction of α-carboradical produced from dimedon by oxidizing with manganese(III) acetate in acetic acid and the chalcone derivatives. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910701862782

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Synthesis of 3‐Aryl‐2‐benzoylbenzofuran
Derivatives using Manganese(III)
Acetate–Mediated Addition of Dimedon to
Chalcone Derivatives
Mustafa Ceylan a & Esra Fındık a
a Faculty of Arts and Sciences, Department of Chemistry , Gaziosmanpasa
University , Tokat, Turkey
Published online: 12 Mar 2008.
To cite this article: Mustafa Ceylan & Esra Fındık (2008) Synthesis of 3‐Aryl‐2‐benzoylbenzofuran
Derivatives using Manganese(III) Acetate–Mediated Addition of Dimedon to Chalcone Derivatives, Synthetic
Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry, 38:7,
1070-1077, DOI: 10.1080/00397910701862782
To link to this article: http://dx.doi.org/10.1080/00397910701862782
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Synthetic Communicationsw, 38: 1070–1077, 2008
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910701862782
Synthesis of 3-Aryl-2-benzoylbenzofuran
Derivatives using Manganese(III)
Acetate–Mediated Addition of Dimedon
to Chalcone Derivatives
Mustafa Ceylan and Esra Fındık
Faculty of Arts and Sciences, Department of Chemistry, Gaziosmanpasa
University, Tokat, Turkey
Abstract: 3-Aryl-2-benzoylbenzofurans were synthesized by the reaction of a-carbor-
adical produced from dimedon by oxidizing with manganese(III) acetate in acetic acid
and the chalcone derivatives.
Keywords: 3-Aryl-2-benzoylbenzofurans, chalcones, dimedon, manganese(III)
acetate
Furans and their derivatives are widely present in nature[1] and are some of
the most important heterocyclic compounds[2] for the total synthesis of
the complicated naturally occurring metabolites in organic chemistry.[3]
Furthermore, polyfunctionalized furans are versatile and convenient
synthetic starting materials for preparation of a variety of heterocyclic
compounds.[4]
It is well known that C-C bonds are formed during the transition-metal-
salt-mediated oxidative addition of 1,3-dicarbonyl compounds to unsaturated
systems. In particular, Mn(OAc)3 is effectively used in the synthesis of
furans[5] and dihydrofurans.[6] Manganese(III) acetate acts as a one-electron
oxidant and is used to form radicals at the a-position of carbonyls and
Received in the U.K. April 18, 2007
Address correspondence to Mustafa Ceylan, Faculty of Arts and Sciences, Depart-
ment of Chemistry, Gaziosmanpasa University, 60250 Tokat, Turkey. E-mail:
mceylan@gop.edu.tr
1070

3-Aryl-2-benzoylbenzofuran Derivatives
1071
Scheme 1.
particularly 1,3-dicarbonyls, which can react with electron-rich alkenes to form
new C-C bonds.[7] Mn(OAc)3-prompted addition of 1,3-dicarbonyl compounds
to alkenes,[8] steric hindered alkenes,[9] bicyclic alkenes,[10] alkines,[11]
imines,[12] and a,b-unsaturated amides[13] have been reported. In this study,
we report the Mn(OAc)3-mediated addition of dimedon as a 1,3-dicarbonyl
compound to chalcone derivatives, which are electron-poor alkenes.
The chalcone derivatives 3a–i, the starting material for the synthesis of
5a–i, were synthesized by the condensation of corresponding benzaldhyde
and acetophenone derivatives in basic medium (Scheme 1). All chalcone
derivatives 3a–i are well known in the literature.[14–16]
The reaction of dimedon with chalcones 3a–i having different functional
groups in the presence of Mn(OAc)3 or Mn(OAc)3/Cu(OAc)2 mixture
resulted in the formation of 3-aryl-2-benzoylbezofuran derivatives 5a–i via
oxidative free-radical cyclization (Scheme 2). As shown in Table 1,
dimedon did not react with the amino-chalcone 5f as it react with the other
chalcone derivatives with lower yields in the presence of the Mn(OAc)3/
Cu(OAc)2 mixture. The experimental results are given in Table 1.
This reaction formed only the desired heterocyclic compounds in one
step, and no other by-products were isolated. Accordingly, we suggest
that the present reaction is a convenient synthetic method of preparing
3-aryl-2-benzoylbenzofurans.
EXPERIMENTAL
Instruments
Melting points were measured on an Electrothermal 9100 apparatus.
IR spectra (KBr disc or CHCl3) were recorded on a Jasco FT/IR-430
Scheme 2.

1072
M. Ceylan and E. Fındık
Table 1. Synthesis of 3-aryl-2-benzoylbenzofuran derivatives by Mn(OAc)3-
or Mn(OAc)3/Cu(OAc)2- promoted oxidative addition of dimedon to chalcone
derivatives
Time
(min)
Isolated
yield (%)
Entry
Ar
Ara
Aa
Bb
Products
A0
Bb
Mp (8C)
1
2
3
4
5
6
7
8
9
4-ClPh
Ph
Ph
Ph
Ph
10
20
15
30
15
15
15
5
15
25
15
45
15
—
5
5a
5b
5c
5d
5e
5f
45
47
41
66
72
62
59
57
45
37
39
38
60
68
—
45
44
36
129–131
127–129
187–190
—
4-BrPh
4-OHPh
4-CH3Ph
4-CH3OPh Ph
4-NH2Ph
—
—
Ph
Ph
Ph
Ph
4-CH3OPh
4-ClPh
4-CH3Ph
5g
5h
5i
109–111
117–119
113–115
15
15
5
aMethod A: Mn(OAc)3 (2 eq).
bMethod B: Mn(OAc)3 (2 eq), Cu(OAc)2 (2eq).
spectrometer. 1H and 13C NMR spectra were recorded on a Varian EM 360 L
instrument. TMS (d 0.00) was the internal standard for 1H NMR and CDCl3
(d 77.0) for 13C NMR spectroscopy; J values are given in hertz. The multipli-
1
cities of the signals in the H NMR spectra are abbreviated by s (singlet),
d (doublet), t (triplet), q (quartet), m (multiplet), br (broad), and combinations
thereof. Elemental analyses were obtained from a Leco CHNS 932 elemental
analyzer.
Reagent
Manganese(III) acetate, copper(II) acetate, acetic acid, and dimedon were
used as commercial products of the highest reagent grade.
All column chromatographies were performed on silica gel (60–230
mesh, Merck).
General Procedure for Synthesis of 3-Aryl-2-benzoylbenzofurans
A solution of manganese(III) acetate (1.9 g, 7.2 mmol) in 15 mL of glacial
acetic acid was heated under a nitrogen atmosphere at 80 8C until a it
dissolved. After Mn(OAc)3 was dissolved completely, the solution was
cooled down to 60 8C. A solution of dimedon (1 g, 7.2 mmol) and chalcone
derivative (1 g, 3.6 mmol) in 5 mL of acetic acid or dimedon (1 g, 7.2 mmol),

3-Aryl-2-benzoylbenzofuran Derivatives
1073
chalcone derivative (1 g, 3.6 mmol), and Cu(OAc)2 (1.43 g, 7.2 mmol) in
10 mL of acetic acid was added to this mixture. The reaction was finished
when the dark brown color of the solution disappeared. Acetic acid was evap-
orated under reduced pressure. The water was added to the residue and extracted
with EtOAc (3 ꢀ 20 mL). The combined organic phases were neutralized with
saturated NaHCO3 solution, dried over anhydrous Na2SO4, and evaporated.
Crude products were purified by column chromatography on silica gel or pre-
parative thin-layer chromatography (TLC) (20 ꢀ 20 cm plates, 2 mm thick)
using n-hexane/EtOAc (9:1) as eluent. The products were crystallized in n-
hexane/EtOAc (9:1).
Data
2-(4-Chlorobenzoyl)-6,6-dimethyl-3-phenyl-2,3,6,7-
tetrahydrobenzofuran-4(5H)-one (5a)
Colorless crystals; mp 129–131 8C; 1H NMR (300 MHz, CDCl3): d ¼ 8.01–
7.96 (brd, 2H, J ¼ 8.7 Hz, ArH, AA0 part of AA0BB0 system), 7.44–7.38
(m, 5H, ArH, BB0 part of AA0BB0 system and 3H), 7.29–7.25 (m, 2H,
ArH), 5.94–5.92 (d, 1H, J ¼ 5.8 Hz, H2, A part of AB system), 4.99–4.97
(ddd as “dt”, 1H, J3,2 ¼ 5.8, J3,7 ¼ 1.3 Hz, H3, B part AB system), 2.58–
2.52 (dd, 1H, J7a,b ¼ 17.6, J7a,3 ¼ 0.9 Hz, H7a), 2.51–2.44 (dd, 1H,
J7b,a ¼ 17.6, J7b,3 ¼ 1.7 Hz, H7b), 2.34–2.28 (d, 1H, J5a,b ¼ 16.2 Hz, H5a),
2.27–2.22 (d, 1H, J5b,a ¼ 16.2 Hz, H5b), 1.20 (s, 3H, CH3), 1.19 (s, 3H,
CH3) ppm; 13C NMR (75 MHz, CDCl3): d ¼ 198.04, 193.54, 177.44,
140.27, 139.41, 134.54, 130.65, 129.15, 128.85, 125.69, 112.63, 90.03,
54.63, 50.95, 37.92, 34.46, 28.63, 28.61; IR (KBr disc) cm21: 3062, 3031,
2958, 2871, 1681, 1637, 1589, 1398, 1213, 1091, 1002, 794, 759, 698.
Anal. calcd. for C23H21ClO3: C, 72.53; H, 5.56. Found: C, 72.77; H, 5.61.
2-(4-Bromobenzoyl)-6,6-dimethyl-3-phenyl-2,3,6,7-
tetrahydrobenzofuran-4(5H)-one (5b)
Colorless crystals; mp 127–129 8C; 1H NMR (300 MHz, CDCl3): d ¼ 7.93–
7.88 (d, 2H, J ¼ 8.6 Hz, ArH, AA0 part of AA0BB0 system), 7.62–7.57 (d, 2H,
J ¼ 8.6 Hz, ArH, BB0 part of AA0BB0 system), 7.45–7.37 (m, 3H, ArH),
7.39–7.25 (m, 2H, ArH), 5.94–5.92 (d, 1H, J ¼ 5.8 Hz, H2, A part of AB
system), 4.98–4.96 (brd, 1H, J ¼ 5.8 Hz, H3, B part AB system), 2.58–
2.52 (dd, 1H, J7a,b ¼ 17.7, J7a,3 ¼ 1.1 Hz, H7a), 2.51–2.44 (dd, 1H,
J7b,a ¼ 17.7, J7b,3 ¼ 1.7 Hz, H7b), 2.34–2.28 (d, 1H, J5a,b ¼ 16.2 Hz, H5a),
2.27–2.21 (d, 1H, J5b,a ¼ 16.2 Hz, H5b), 1.20 (s, 3H, CH3), 1.19 (s, 3H,
CH3) ppm; 13C NMR (75 MHz, CDCl3): d ¼ 198.26, 193.54, 177.44,
139.39, 135.00 131.85, 130.73, 129.16, 125.68, 112.61, 90.02, 54.62, 50.95,
37.93, 34.46, 28.63, 28.61; IR (KBr disc) cm21: 3062, 3035, 2958, 2927,

1074
M. Ceylan and E. Fındık
2857, 1679, 1637, 1583, 1396, 1211, 1070, 1001, 757, 698. Anal. calcd. for
C23H21BrO3: C, 64.95; H, 4.98. Found: C, 64.96; H, 5.02.
2-(4-Hydroxybenzoyl)-6,6-dimethyl-3-phenyl-2,3,6,7-
tetrahydrobenzofuran-4(5H)-one (5c)
Colorless crystals; mp 187–190 8C; 1H NMR (300 MHz, CDCl3):
d ¼ 9.21–8.67 (brs, 1H, OH), 7.81–7.78 (brd, 2H, J ¼ 8.8 Hz, ArH, AA0 part
of AA0XX0 system), 7.45–7.36 (m, 3H, ArH), 7.30–7.25 (m, 2H, ArH), 6.67–
6.64 (brd, 2H, J ¼ 8.8 Hz, XX0 part of AA0XX0 system), 5.97–5.95 (d, 1H,
J ¼ 5.5 Hz, H2, A part of AB system), 5.00–4.98 (d, 1H, J ¼ 5.5 Hz, H3, B
part AB system), 2.63–2.57 (dd, 1H, J7a,b ¼ 16.9, J7a,3 ¼ 0.8 Hz, H7a), 2.54–
2.48 (dd, 1H, J7b,a ¼ 16.9, J7b,3 ¼ 1.3 Hz, H7b), 2.42–2.37 (d, 1H,
J5a,b ¼ 16.4 Hz, H5a), 2.34–2.29 (d, 1H, J5b,a ¼ 16.4 Hz, H5b), 1.23 (s, 3H,
CH3), 1.21 (s, 3H, CH3) ppm; 13C NMR (75 MHz, CDCl3): d ¼ 196.99,
195.70, 179.88, 162.35, 139.33, 131.71, 129.13, 129.08, 127.96, 125.67,
115.51, 113.06, 90.93, 53.45, 50.77, 38.03, 34.67, 28.58 (2C); IR (KBr disc)
cm21: 3249, 3066, 3031, 2960, 2890, 2815, 1617, 1602, 1579, 1400, 1284,
1226, 1170, 759, 736, 700. Anal. calcd. for C23H22O4: C, 76.22; H, 6.12.
Found: C, 76.67; H, 6.51.
6,6-Dimethyl-2-(4-methylbenzoyl)-3-phenyl-2,3,6,7-
tetrahydrobenzofuran-4(5H)-one (5d)
Viscous oil; 1H NMR (300 MHz, CDCl3): d ¼ 7.94–7.91 (d, 2H, J ¼ 8.2 Hz,
ArH, AA0 part of AA0BB0 system), 7.42–7.38 (m, 2H, ArH), 7.31–7.24
(m, 5H, BB0 part of AA0BB0 system and 3H), 5.91–5.89 (d, 1H, J ¼ 5.6 Hz,
H2, A part of AB system), 5.04–5.02 (d, 1H, J ¼ 5.6 Hz, H3, B part AB
system), 2.58–2.52 (dd, 1H, J7a,b ¼ 17.6, J7a,3 ¼ 0.9 Hz, H7a), 2.51–2.44
(dd, 1H, J7b,a ¼ 17.6, J7b,3 ¼ 1.7 Hz, H7b), 2.34–2.28 (d, 1H,
J5a,b ¼ 16.2 Hz, H5a), 2.27–2.22 (d, 1H, J5b,a ¼ 16.2 Hz, H5b), 1.22 (s, 3H,
CH3), 1.19 (s, 3H, CH3) ppm; 13C NMR (75 MHz, CDCl3): d ¼ 198.47,
193.63, 177.31, 144.64, 139.64 133.71, 129.37, 129.26, 129.08, 129.02,
125.77, 112.78, 90.10, 54.44, 50.98, 37.93, 34.46, 29.73, 28.67, 28.38; IR
(CHCl3) cm21: 3031, 2956, 2925, 2854, 1677, 1643, 1606, 1455, 1396,
1226, 1182, 757, 698. Anal. calcd. for C24H24O3: C, 79.97; H, 6.71. Found:
C, 79.96; H, 6.83.
2-(4-Methoxybenzoyl)-6,6-dimethyl-3-phenyl-2,3,6,7-
tetrahydrobenzofuran-4(5H)-one (5e)
Viscous oil; 1H NMR (300 MHz, CDCl3): d ¼ 8.04–7.98 (brd, 2H,
J ¼ 8.9 Hz, ArH, AA0 part of AA0XX0 system), 7.44–7.37 (m, 3H, ArH),
7.31–7.26 (m, 2H, ArH), 6.93–6.90 (brd, 2H, J ¼ 8.9 Hz, XX0 part of
AA0XX0 system), 5.92–5.95 (d, 1H, J ¼ 5.6 Hz, H2, A part of AB system),

3-Aryl-2-benzoylbenzofuran Derivatives
1075
5.01–4.99 (d, 1H, J ¼ 5.6 Hz, H3, B part AB system), 3.84 (s, 3H, -OCH3),
2.57–2.52 (dd, 1H, J7a,b ¼ 17.1, J7a,3 ¼ 0.8 Hz, H7a), 2.50–2.43 (dd, 1H,
J7b,a ¼ 17.1, J7b,3 ¼ 1.6 Hz, H7b), 2.34–2.29 (d, 1H, J5a,b ¼ 16.2 Hz, H5a),
2.27–2.22 (d, 1H, J5b,a ¼ 16.2 Hz, H5b), 1.21 (s, 3H, CH3), 1.18 (s, 3H,
CH3) ppm; 13C NMR (75 MHz, CDCl3): d ¼ 197.20, 193.67, 177.31,
164.05, 139.74, 131.67, 129.19, 129.07, 128.98, 125.74, 113.73, 112.76,
90.12, 55.48, 54.24, 51.00, 37.92, 34.44, 28.64, 28.63; IR (CHCl3) cm21
:
3062, 3031, 3008, 2958, 2927, 2857, 1639, 1598, 1573, 1396, 1263, 1224,
1172, 1029, 757, 700. Anal. calcd. for C24H24O4: C, 76.57; H, 6.43. Found:
C, 76.35; H, 6.45.
2-(4-Aminobenzoyl)-6,6-dimethyl-3-phenyl-2,3,6,7-
tetrahydrobenzofuran-4(5H)-one (5f)
Yellow oil; 1H NMR (300 MHz, CDCl3): d ¼ 7.86–7.84 (d, 2H, J ¼ 8.5 Hz,
ArH, AA0 part of AA0XX0 system), 7.41–7.28 (m, 5H, ArH), 6.62–6.58
(d, 2H, J ¼ 8.5 Hz, XX0 part of AA0XX0 system), 5.88–5.86 (d, 1H,
J ¼ 5.5 Hz, H2, A part of AB system), 4.95–4.93 (d, 1H, J ¼ 5.5 Hz, H3,
B part AB system), 2.58–2.52 (d, 1H, J7a,b ¼ 17.8, H7a), 2.49–2.43 (d, 1H,
J7b,a ¼ 17.8 Hz, H7b), 2.35–2.30 (d, 1H, J5a,b ¼ 16.3 Hz, H5a), 2.27–2.22
(d, 1H, J5b,a ¼ 16.3 Hz, H5b), 1.21 (s, 3H, CH3), 1.18 (s, 3H, CH3) ppm;
13C NMR (75 MHz, CDCl3): d ¼ 196.43, 193.79, 177.26, 151.72, 139.89,
131.91, 129.01, 128.88, 126.51, 125.76, 113.70, 112.88, 90.21, 53.88,
51.06, 37.95, 34.45, 28.70, 28.62; IR (CHCl3) cm21: 3367, 3064, 2956,
2927, 2857, 1662, 1592, 1562, 1440, 1299, 1218, 1176, 997, 784, 763.
Anal. calcd. for C23H23NO3: C, 76.43; H, 6.41; N, 3.88. Found: C, 76.77;
H, 6.61; N, 4.18.
2-Benzoyl-3-(4-methoxyphenyl)-6,6-dimethyl-2,3,6,7-
tetrahydrobenzofuran-4(5H)-one (5g)
Colorlesscrystals;mp109–1118C; 1H NMR (300 MHz, CDCl3):d ¼ 8.01–7.97
(dd, 2H, J ¼ 7.8 Hz, ArH), 7.60–7.54 (tt, 1H, J ¼ 7.3, 1.3 Hz, ArH), 7.46–7.41
(brt, 2H, J ¼ 7.8 Hz, ArH), 7.26–7.22 (brd, 2H, J ¼ 8.6 Hz, ArH, AA0 part of
AA0BB0 system), 6.95–6.91 (brd, 2H, J ¼ 8.6 Hz, BB0 part of AA0BB0
system), 5.82–5.80 (d, 1H, J ¼ 5.8 Hz, H2, A part of AB system), 5.06–5.04
(d, 1H, J ¼ 5.8 Hz, H3, B part AB system), 3.83 (s, 3H, -OCH3), 2.55–2.49
(dd, 1H, J7a,b ¼ 17.5, J7a,3 ¼ 0.9 Hz, H7a), 2.47–2.41 (dd, 1H, J7b,a ¼ 17.5,
J7b,3 ¼ 1.7 Hz, H7b), 2.36–2.30 (d, 1H, J5a,b ¼ 16.2 Hz, H5a), 2.28–2.23
(d, 1H, J5b,a ¼ 16.2 Hz, H5b), 1.22 (s, 3H, CH3), 1.18 (s, 3H, CH3) ppm; 13C
NMR (75 MHz, CDCl3): d ¼ 199.02, 193.57, 177.18, 160.21, 136.26, 133.62,
131.50, 129.14, 128.55, 127.54, 114.44, 112.76, 90.12, 76.67, 55.37, 54.43,
50.96, 37.96, 34.46, 28.68, 28.61; IR (KBr disc) cm21: 3062, 3004, 2958,
2927, 2871, 1681, 1637, 1515, 1396, 1251, 1216, 1178, 1033, 794, 692. Anal.
calcd. for C24H24O4: C, 76.57; H, 6.43. Found: C, 76.35; H, 6.45.

1076
M. Ceylan and E. Fındık
2-Benzoyl-3-(4-chlorophenyl)-6,6-dimethyl-2,3,6,7-
tetrahydrobenzofuran-4(5H)-one (5h)
Colorless crystals; mp 117–119 8C; 1H NMR (300 MHz, CDCl3): d ¼ 8.02–
7.99 (dd, 2H, J ¼ 7.1 Hz, ArH), 7.61–7.55 (tt, 1H, J ¼ 7.3, 1.2 Hz, ArH),
7.47–7.42 (brt, 2H, J ¼ 7.6 Hz, ArH), 7.24–7.21 (brd, 2H, J ¼ 8.3 Hz,
ArH, AA0 part of AA0BB0 system), 7.20–7.17 (brd, 2H, J ¼ 8.3 Hz, BB0
part of AA0BB0 system), 5.88–5.86 (d, 1H, J ¼ 5.8 Hz, H2, A part of AB
system), 5.04–4.98 (d, 1H, J ¼ 5.8 Hz, H3, B part AB system), 2.57–2.51
(dd, 1H, J7a,b ¼ 17.6, J7a,3 ¼ 0.9 Hz, H7a), 2.50–2.43 (dd, 1H, J7b,a ¼ 17.6,
J7b,3 ¼ 1.7 Hz, H7b), 2.34–2.28 (d, 1H, J5a,b ¼ 16.2 Hz, H5a), 2.27–2.22
(d, 1H, J5b,a ¼ 16.2 Hz, H5b), 1.21 (s, 3H, CH3), 1.19 (s, 3H, CH3) ppm;
13C NMR (75 MHz, CDCl3): d ¼ 198.82, 193.48, 177.11, 138.05, 136.17,
134.91, 133.81, 129.31, 129.15, 128.62, 127.15, 112.77, 89.26, 54.52,
50.94, 37.88, 34.47, 28.69, 28.56; IR (KBr disc) cm21: 3062, 3031,
2958, 2871, 1681, 1643, 1596, 1492, 1394, 1216, 794. Anal. calcd. for
C23H21ClO3: C, 72.53; H, 5.56. Found: C, 72.87; H, 5.64.
2-Benzoyl-6,6-dimethyl-3-p-tolyl-2,3,6,7-
tetrahydrobenzofuran-4(5H)-one (5i)
Colorless crystals; mp 113–115 8C; 1H NMR (300 MHz, CDCl3): d ¼ 8.03–
7.99 (dd, 2H, J ¼ 7.8 Hz, ArH), 7.62–7.57 (tt, 1H, J ¼ 7.3, 1.2 Hz, ArH),
7.48–7.44 (brt, 2H, J ¼ 7.8 Hz, ArH), 7.39–7.37 (brd, 2H, J ¼ 8.5 Hz,
ArH, AA0 part of AA0BB0 system), 7.25–7.19 (brd, 2H, J ¼ 8.5 Hz, BB0
part of AA0BB0 system), 5.85–5.83 (d, 1H, J ¼ 5.6 Hz, H2, A part of AB
system), 5.06–5.04 (d, 1H, J ¼ 5.6 Hz, H3, B part AB system), 2.57–2.51
(dd, 1H, J7a,b ¼ 17.5, J7a,3 ¼ 0.8 Hz, H7a), 2.49–2.43 (dd, 1H, J7b,a ¼ 17.5,
J7b,3 ¼ 1.7 Hz, H7b), 2.36–2.30 (d, 1H, J5a,b ¼ 16.2 Hz, H5a), 2.29–2.23
(d, 1H, J5b,a ¼ 16.2 Hz, H5b), 1.22 (s, 3H, CH3), 1.19 (s, 3H, CH3) ppm;
13C NMR (75 MHz, CDCl3): d ¼ 199.10, 193.57, 177.28, 139.10, 136.54,
136.28, 133.62, 129.76, 129.17, 128.54, 125.88, 112.80, 90.17, 54.48,
50.97, 37.95, 34.46, 28.69, 28.61, 21.27; IR (KBr disc) cm21: 3056,
3027, 2958, 2929, 2883, 1681, 1641, 1596, 1394, 1216, 1049, 790,
759, 692. Anal. calcd. for C24H24O3: C, 79.97; H, 6.71. Found: C, 79.86; H,
6.83.
ACKNOWLEDGMENT
The authors are indebted to the Department of Chemistry (Gaziosmapasa
University) and the Scientific and Technical Research Council of Turkey
(Grant TUBITAK-TBAG 106T103) for financial support.

3-Aryl-2-benzoylbenzofuran Derivatives
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