Green synthesis of aurones and related compounds under solvent-free conditions

Article abstract of DOI:10.3184/174751916X14719593488659

3-Coumaranones were condensed with aldehydes on alumina or alumina-potassium fluoride without solvent under microwave irradiation or classical heating. Novel aurones and analogues bearing ferrocenyl, benzodioxole or benzodioxane groups were obtained in go

Full text of DOI:10.3184/174751916X14719593488659

JOURNAL OF CHEMICAL RESEARCH 2016
VOL. 40 SEPTEMBER, 567–569
RESEARCH PAPER 567
Green synthesis of aurones and related compounds under solvent-free
conditions
a,b
a
a
b
Karima Boussafi , Didier Villemin *, Nathalie Bar and Mabrouk Belghosi
a
ENSICAEN, LCMT, UMR CNRS 6507, Normandie Université France, INC3M, FR 3038, Labex EMC3, Labex SynOrg, 14050 Caen, France
University of Jijel, Pharmacology and Phytochemistry Laboratory, Department of Chemistry, Faculty of Sciences, Jijel, Algeria
b
3
-Coumaranones were condensed with aldehydes on alumina or alumina–potassium fluoride without solvent under microwave irradiation
or classical heating. Novel aurones and analogues bearing ferrocenyl, benzodioxole or benzodioxane groups were obtained in good yields
without use of heavy metal reagents.
Keywords: aurone, ferrocene, solventless reaction, microwave
Aurones (2-benzylidene-1-benzofuran-3(2H)-ones) are natural
compounds occurring as yellow dyes in plants and constitute
a small part of a larger family of natural products known
been reported. Ferrocenyl aurones were introduced recently
12–14
by Jaouen and co-workers
for inducing morphological
modifications of endothelial cells and as cytotoxic compounds
against B16 murine melanoma cells.
1
as flavonoids. The class of flavonoids includes flavones,
isoflavones, chalcones and aurones, and are mainly secondary
metabolites of plants found in fruits and flowers. Aurones are
structuralisomersofflavones. Theyarelessstudiedprobablydue
to their low content in plants. Aurones are known for displaying
In this work, we decided to prepare aurones using a green
approach, with a minimum of solvent. For this reason, we
used solvent-free synthesis of aurones on alumina or alumina–
potassium fluoride according to Scheme 1.
2
a wide variety of biological activities: they are described as
Alumina–potassium fluoride is a much more basic catalyst
15
enzyme inhibitors (tyrosinase, iodothyronine deiodinase,
acetylcholinesterase, hepatitis C virus RNA-dependent RNA
polymerase), and also as anticancer, antibacterial, antifungal,
antioxidant, antiparasite (Plasmodium falciparum) and insect
antifeedant agents.
than alumina and conducive to better yields than alumina;
however, alumina was preferred in the case of function-free
phenol. In fact, in the presence of potassium fluoride on alumina
with coumaran-3-ones bearing a hydroxyl group, a phenate
potassium salt was formed, which led to difficulties in aurone
desorption, so in this case alumina was preferable as support.
Furthermore, the reactions without solvent were accelerated by
Two types of synthesis of aurones have been generally reported.
The first is the condensation of 3-coumaranones with aldehydes.
3
16
The reaction is catalysed by alumina, alumina–potassium
microwave heating. Yields obtained were found to be similar
4
5
6
fluoride, barium oxide, or eutectic choline chloride–urea. The
second methodology, analogous to the biosynthesis of aurones, is
the oxidative rearrangement of chalcones in the presence of toxic
under microwave irradiation and classical heating (Table 1).
All the reactions were stereospecific and the stereochemistry
obtained for all the compounds was Z, this configuration
corresponding to the configuration of natural aurones. The
7
8
9
metal salts such as thallium, mercury, or gold oxidants.
10,17
The use of heavy metal salts (Ba, Tl, Hg, Au) has been
aurones 1a, 1b, 3b and 3d have already been reported.
5,7–10
recently described;
however, the use of heavy metals can
To our knowledge, all other aurones described herein in the
experimental part have never been reported. The biological
properties of these new aurones are under study.
be problematic for the preparation of drugs because traces of
heavy metals can influence the results of biological tests. To
achieve synthesis of new aurones under green conditions
without the use of heavy metals, we have extended the
Conclusion
4
scope of our work on the 3-coumaranone condensation. We
Condensation under solvent-free conditions of 3-coumaranones
with aldehydes on classical heating or under microwave
irradiation in the presence of alumina or alumina–potassium
fluoride allowed the synthesis of new potentially biological
aurones containing benzodioxane, benzodioxole, or ferrocenyl
groups without the use of heavy metal reagents.
were interested in the synthesis of novel aurones carrying
2
,3-dihydro-1,4-benzodioxin, 1,3-benzodioxol and ferrocenyl
groups. 2,3-dihydro-1,4-benzodioxine and 1,3-benzodioxole are
11
known for their biological properties, but aurone derivatives of
2
,3-dihydro-1,4-benzodioxine and 1,3-benzodioxole have not
Al O -KF
R1
2
3
R
1
R3
O
O
or Al O
3
H
R3
2
+
solvent free
0-70°C or
microwave
O
5
O
O
R2
R
2
1
R = OH, R = H; 2 R = OMe, R = H; 3 R = OH, R = OH; 4 R = OMe, R = OMe; 5 naphthofuran-3(2H)-one.
1 2 1 2 1 2 1 2
a Ferrocene carboxaldehyde; b 1,3-benzodioxole-5-carboxaldehyde (piperonal); c 1,4-benzodioxane-6-carboxaldehyde;
d 3,4,5-trimethoxybenzaldehyde.
Scheme 1 Condensation of 3-coumaranones 1–5 with aldehydes a–d.
*
Correspondent. E-mail: villemin@ensicaen.fr

568 JOURNAL OF CHEMICAL RESEARCH 2016
Table 1 Dry condensation of 3-coumaranones (1–5) with aldehydes
a–d)
0.66 mmol) and 1,4-benzodioxane-2-carboxaldehyde (169 mg, 1.03 mol) to
afford the product as: Pure yellow solid; yield 168 mg (86%); m.p. 230 °C;
(
a
1
3
-Coumaranone Aldehyde Catalyst
Product
1a
1c
2a
2c
2d
3b
3c
3d
Yield/%
75
86
H NMR (400 MHz, DMSO-d ): δ 7.34 (s, 1H), 7.28 (d, 1H, J = 8.4 Hz),
6
1
1
2
2
2
3
3
3
4
5
5
a
c
a
c
d
b
c
d
c
a
b
Al2O3
Al2O3
7.07 (d, 1H, J = 8.8 Hz), 6.89 (d, 1H, J = 8.4 Hz), 6.17 (s, 1H), 5.86 (d, 1H,
13
J = 8.8 Hz), 5.68 (brs, 1H), 4.27 (s, 4H); C NMR (400 MHz, DMSO-d ):
6
Al O –KF
88
182.5, 176.3, 170.1, 150.3, 144.8, 143.7, 127.6, 124.7, 123.9, 120.6, 118.5,
2
3
−1
1
17.8, 104.2, 103.2, 98.6, 64.8, 64.5; IR (cm ): 3290 (OH), 1667 (C=O),
Al O –KF
86
91, 90
53, 55
2
3
b
1489–1620 (C=C), 1221 (C–O–C). MS (ES+) m/z (% relative abundance):
319 (M + Na, 100), 615 (2M + Na, 40); MS (ES−) m/z (% relative
abundance): 295 (M − H, 100); HRMS (ESI) calcd for C H O : 297.0763;
Al O –KF
2
3
b
Al2O3
Al2O3
Al2O3
86
58, 57
17 13
5
+
found: 297.0762 (M + H ).
b
Al O –KF
4c
5a
5b
88
53
75, 74
(Z)-2-[(ferrocenyl)methylidene]-6-methoxy-1-benzofuran-3(2H)-one,
C H FeO (2a)
2
3
Al O –KF
2
3
20 16
3
b
Al O –KF
Compound 2a was obtained by condensation of 6-methoxybenzofuran-
3(2H)-one (108 mg, 0.66 mmol) and ferrocenecarboxaldehyde (141 mg,
0.66 mmol), according to classical heating procedure B to afford the
2
3
a
b
Yields under classical heating.
Yields under microwave heating.
1
product as: Pure violet solid; yield 209 mg (88%); m.p. 142 °C; H NMR
(
400 MHz, DMSO-d ): δ 7.66 (d, 1H, J = 8.4 Hz), 7.13 (d, 1H), 6.83 (dd,
H), 6.78 (s, 1H), 4.92 (s, 2H), 4.61 (s, 2H), 4.21 (s, 5H), 3.93 (s, 3H);
Experimental
6
1
IR spectra were performed on solid samples using a Fourier transform
Perkin Elmer Spectrum with ATR accessory. Only significant absorptions
1
3
C NMR (400 MHz, DMSO-d ): δ 180.7, 168.9, 164.0, 146.5, 126.4,
6
−1
1
1
3
15.4, 114.5, 111.8, 96.3, 73.8, 71.7, 71.1, 69.9, 55.7; IR (cm ): 1684 (C=O),
1
13
are listed. The H NMR and C NMR spectra were recorded on
Bruker AC 400 spectrometers at 400 MHz. Samples were recorded in
DMSO-d-6 solutions using TMS as an internal standard. The chemical
shifts are expressed in δ units (ppm) and quoted downfield from TMS.
The multiplicities are reported as: s, singlet; d, doublet; t, triplet; q,
quartet; m, multiplet (for details see ESI file) recorded on Waters mass
spectrometers: QTOF Micro (ESI), Xevo G2-XS QTof (ESI) or Autospec
635–1495 (C=C), 1222 (C–O–C); HRMS (EI) calcd for C H FeO :
2
0
16
3
+
60.0449; found: 360.0462 (M ).
(Z)-2-[(2,3-dihydro-1,4-benzodioxin-2-yl)methylidene]-6-methoxy-1-
benzofuran-3(2H)-one, C H O (2c)
18
14
5
According to procedure A, using classical heating, compound 2c was
prepared by condensation of 6-methoxybenzofuran-3(2H)-one (108 mg,
0
The crude product was recrystallised from methanol to afford the product
as: Pure yellow solid; yield 176 mg (86%); m.p. 183 °C; H NMR (400
(
EI). Microwave irradiations were performed at 2450 MHz with an Anton
.66 mmol) and 1,4-benzodioxane-2-carboxaldehyde (129 mg, 0.79 mol.).
Paar monowave 300.
1
8
6
-hydroxybenzofuran-3(2H)-one
(1),
6-methoxybenzofuran-
1
19,20
21,22
3
4
(2H)-one
(2),
4,6-dihydroxybenzofuran-3(2H)-one
(3),
MHz, DMSO-d ): δ 7.68 (d, 1H), 7.55 (d, 1H), 7.48 (dd, 1H), 7.18 (d, 1H),
2
3,24
6
,6-dimethoxybenzofuran-3(2H)-one (4),
and naphthofuran-3(2H)-
6
.98 (d, 1H), 6.85 (dd, 1H), 6.78 (s, 1H), 4.35–4.27 (m, 4H), 3.92 (s, 3H);
4
one (5) were prepared according to the literature. Aldehydes were
commercial products (Alfa Aesar). Potassium fluoride on alumina was
prepared according to the literature.
1
3
C NMR (400 MHz, DMSO-d ): δ 181.9, 168.2, 167.7, 146.8, 145.8, 144.0,
6
2
5
125.8, 125.76, 125.70, 120.1, 118.1, 114.5, 113.2, 111.7, 97.6, 64.9, 64.4, 56.9.
IR (cm ): 1685 (C=O), 1637–1496 (C=C), 1221 (C–O–C). MS m/z (%
−1
Synthesis of aurone derivatives; general procedure
relative abundance): 333 (M + Na, 75), 643 (2M + Na, 100); HRMS (EI)
+
Classical heating procedure A: 1g of Al O –KF was added to the
calcd for C H O : 310.08413; found: 310.0108 (M ).
2
3
18 14
5
benzofuranone derivative (0.6 mmol) and the aldehyde (1.0–1.5 eq)
dissolved in acetonitrile (1–2 mL). The mixture was evaporated under
vacuum and the resulting solid was heated at 70 °C until TLC showed
disappearance of the starting material (3–8 h). The mixture was extracted
with ethanol and Al O –KF was removed by filtration. The filtrate was
(
3
Z)-6-methoxy-2-[(3,4,5-trimethoxyphenyl)methylidene]-1-benzofuran-
(2H)-one, C H O (2d)
19 18
6
According to procedure A, under both classical and microwave heating,
compound 2d was prepared by condensation of 6-methoxybenzofuran-
3(2H)-one (108 mg, 0.66 mmol) and 3,4,5-trimethoxybenzaldehyde
(194 mg, 0.99 mmol). The crude product was recrystallised from ethanol
to afford the product as: Pure yellow solid; yield 206 mg (91%) under
classical heating, 204 mg (90%) under microwave heating; m.p. = 175 °C;
2
3
evaporated under reduced pressure to afford the corresponding crude
aurone.
Classical heating procedure B: The same as procedure A but with Al O3
2
instead of Al O –KF.
2
3
1
Microwave heating: Procedures A or B were used. The classical heating
was substituted by microwave irradiation performed at 150 °C for 10 min.
H NMR (400 MHz, DMSO-d ): δ 7.68 (d, 1H), 7.34 (s, 2H), 7.18 (d,
6
1H), 6.86 (dd, 1H), 6.81 (s, 1H), 3.93 (s, 3H), 3.86 (s, 6H), 3.73 (s, 3H);
13
C NMR (400 MHz, DMSO-d ): δ 186.6, 165.3, 164.9, 152.0, 146.1, 138.7,
(
Z)-2-[(ferrocenyl)methylidene]-6-hydroxy-1-benzofuran-3(2H)-one,
6
−1
1
1
25.5, 116.0, 113.5, 111.6, 106.0, 96.0, 60.6, 56.8, 56.7, 56.1; IR (cm ):
C H FeO (1a)
19
14
3
700 (C=O), 1602–1458 (C=C), 1230 (C–O–C). MS m/z (% relative
Compound 1a was obtained by condensation of 6-hydroxybenzofuran-
(2H)-one (100 mg, 0.66 mmol) and ferrocenecarboxaldehyde (142 mg,
.66 mmol), according to procedure B, to afford the product as: Pure
abundance): 365 (M + Na, 70), 707 (2M + Na, 100); HRMS (ESI) calcd
for C H O : 343.1182; found: 343.1181 (M + H ).
3
+
0
19 19
6
1
violet solid; yield 171 mg (75%); m.p. >230 °C (dec.); H NMR (400 MHz,
(
Z)-4,6-dihydroxy-2-[(1,3-benzodioxol-5-yl)methylidene]-1-benzofuran-
DMSO-d ): δ 7.07 (d, 1H, J = 8.0 Hz), 6.13 (s, 1H), 5.90 (d, 1H, J = 8.0 Hz),
6
3(2H)-one, C H O (3b)
16
10
6
13
5
.72 (s, 1H), 4.72 (s, 2H), 4.39 (s, 2H), 4.13 (s, 5H); C NMR (400 MHz,
The product was obtained by condensation of 4,6-dihydroxy-benzofuran-
(2H)-one (109 mg, 0.66 mmol) and piperonal (99 mg, 0.66 mol)
DMSO-d ): δ 181.3, 167.3, 165.9, 146.5, 126.4, 114.5, 113.4, 111.9, 96.3,
6
3
−1
7
4.1, 71.2, 71.1, 69.9; IR (cm ): 3295 (OH), 1666 (C=O), 1622–1500
according to procedure A under both classical and microwave heating
as: Pure yellow solid; yield 104 mg (53%) under classical heating, 108
mg (55%) under microwave heating; m.p. 276 °C; H NMR (400 MHz,
(
C=C), 1223 (C–O–C); HRMS (EI) calcd for C H FeO : 346.0292;
19
14
3
+
found: 346.0296 (M ).
1
(
Z)-2-[2,3-dihydro-1,4-benzodioxin-2-yl)methylidene]-6-hydroxy-1-
DMSO-d ): δ 7.52–7.39 (m, 2H), 7.04 (s, 1H), 6.56 (s, 1H), 6.19 (s, 1H),
6
13
benzofuran-3(2H)-one, C H O (1c)
6.09 (s, 2H), 6.04 (s, 1H); C NMR (400 MHz, DMSO-d ): δ 183.0, 166.0,
1
7
12
5
6
According to procedure B, with classical heating, compound 1c was
prepared by condensation of 6-hydroxybenzofuran-3(2H)-one (100 mg,
164.0, 160.7, 147.6, 147.0, 147.0, 146.5, 111.7, 113.0, 110.1, 102.2, 99.6, 97.3;
+
HRMS (EI) calcd for C H O : 298.0477; found: 298.0502 (M ).
16
10
6

JOURNAL OF CHEMICAL RESEARCH 2016 569
(
1
Z)-4,6-dihydroxy-2-[(2,3-dihydro-1,4-benzodioxin-2-yl)methylidene]-
-benzofuran-3(2H)-one, C H O (3c)
product as: Pure green solid; yield 154 mg (74%) under classical heating,
156 mg (75%) under microwave heating; m.p. 218 °C; H NMR (400 MHz,
1
17
12
6
According to the procedure B, with classical heating, compound 3c was
prepared by condensation of 4,6-dihydroxybenzofuran-3(2H)-one
DMSO-d ): δ 8.72 (d, 1H), 8.41 (d, 1H), 8.12 (d, 1H), 7.82–7.77 (m, 2H),
6
7.69 (d, 1H), 7.64–7.58 (m, 2H), 7.11 (d, 1H), 7.02 (s, 1H), 6.15 (s, 2H);
(128 mg, 0.66 mmol) and 1,4-benzodioxane-6-carboxaldehyde (128
13
C NMR (400 MHz, DMSO-d ): δ 180.4, 160.0, 148.4, 148.2, 147.2,
6
mg, 0.78 mol), to afford the product as: Pure orange solid; yield 177
1
35.0, 134.4, 130.0, 128.4, 127.8, 127.7, 125.6, 124.4, 123.2, 115.0, 113.0,
1
mg (86%); m.p. 260 °C; H NMR (400 MHz, DMSO-d ): δ 7.45–7.35
−1
6
111.2, 109.3, 108.9, 96.3. IR (cm ): 1682 (C=O), 1636–1482 (C=C), 1223
13
(m, 2H), 6.95 (d, 1H), 6.45 (s, 1H), 5.75 (s, 2H), 4.28 (s, 4H); C NMR
(
(
C–O–C); HRMS (EI) calcd for C H O : 316.0736; found: 316.0706
M ).
20 12 4
(
400 MHz, DMSO-d ): δ 182.4, 168.5, 164.1, 160.3, 158.0, 147.1, 123.9,
6
+
−1
1
(
24.2, 117.9, 112.9, 103.0, 96.6, 95.6, 75.3. IR (cm ): 3287 (OH), 1664
C=O), 1500–1622 (C=C), 1222 (C–O–C); MS (ES+) m/z (% relative
abundance): 313 (M + H, 50), 335 (M + Na, 100), 647 (2M + Na, 30); MS
ES) m/z (% relative abundance): 311 (M − H, 100); HRMS (EI) calcd for
The authors thank Karine Jarsalé for the mass spectroscopic
data. We gratefully acknowledge financial support from the
‘Ministère de la Recherche et des Nouvelles Technologies’, CNRS
(
+
C H O : 312.0634; found: 312.0600 (M ).
17
12
6
(
Centre National de la Recherche Scientifique), the ‘Région
(
Z)-4,6-dihydroxy-2-[(3,4,5-trimethoxyphenyl)methylidene]-1-
Basse-Normandie’ and the European Union (FEDER funding).
The authors acknowledge the financial support of the French
Agence Nationale de la Recherche (ANR), through the program
“Investissements d’Avenir” (ANR-10-LABX-09-01), LabEx
benzofuran-3(2H)-one, C H O (3d)
18
16
7
According to procedure B, under both classical and microwave heating,
compound 3d was obtained by condensation of 4,6-dihydroxybenzofuran-
3
(2H)-one (109 mg, 0.66 mmol) and 3,4,5-trimethoxybenzaldehyde (194
3
mg, 0.99 mol), and was purified by column chromatography, to afford
EMC .
the product as: Orange solid; yield 132 mg (58%) under classical heating,
1
1
30 mg (57%) under microwave heating; m.p. 266 °C; H NMR (400
Electronic Supplementary Information
MHz, DMSO-d ): δ 11.09 (s, 1H), 10.96 (s, 1H), 7.26 (s, 2H), 6.57 (s,
6
The ESI is available through:
stl.publisher.ingentaconnect.com/content/stl/jcr/supp-data
13
1H), 6.26 (s, 1H), 6.13 (s, 1H), 3.84 (s, 6H), 3.71 (s, 3H); C NMR (400
MHz, DMSO-d ): δ 181.8, 165.0, 163.9, 160.0, 153.0, 145.7, 138.7, 110.2,
6
1
06.0, 100.2, 99.1, 92.0, 56.8, 56.1, 60.6; HRMS (EI) calcd for C H O :
18
16
7
+
Received 5 May 2016; accepted 20 July 2016
Paper 1604087 doi: 10.3184/174751916X14719593488659
Published online: 6 September 2016
344.0896; found: 344.0878 (M ).
(
1
Z)-4,6-dimethoxy-2-[(2,3-dihydro-1,4-benzodioxin-2-yl)methylidene]-
-benzofuran-3(2H)-one, C H O (4c)
1
9
16
6
According to procedure A, with classical heating (4c) was prepared by
condensation of 4,6-dimethoxybenzofuran-3(2H)-one (100 mg, 0.51
mmol) and 1,4-benzodioxane-2-carboxaldehyde (108 mg). The crude
References
1
R. Ikans, Natural compounds: a laboratory guide, Academic Press, San
Diego, 1991.
product was recrystallised from methanol to afford the product as: Pure
2
3
4
5
6
7
8
9
A. Boumendjel, Curr.Med.Chem., 2006, 10, 2621.
1
yellow solid; 153 mg (88%); m.p. 173 °C; H NMR (400 MHz, DMSO-d ):
6
R.S. Varma and M. Varma, Tetrahedron Lett., 1992, 33, 5937.
D. Villemin, B. Martin and N. Bar, Molecules, 1998, 3, 88.
S. Kumar, Green Chem. Let. Rev., 2014, 7, 95.
I. Hawkins and S.T. Handy, Tetrahedron, 2013, 69, 9200.
K. Thakkar and M. Cushman, Tetrahedron Lett., 1994, 35, 6441.
N.N. Agrawal and P.A. Soni, Ind. J. Chem., 2006, 45B, 1301.
H. Harkat, A. Blanc, J. Weibel and P. Pale, J. Org. Chem., 2008, 73, 1620.
δ 7.50 (d, 1H), 7.43 (dd, 1H), 6.96 (d, 1H), 6.73 (d, 1H), 6.63 (s, 1H), 6.34
13
(
d, 1H), 4.33–4.25 (m, 4H,), 3.91 (s, 3H), 3.88 (s, 3H); C NMR 400 MHz,
DMSO-d ): δ 181.9, 168.2, 167.7, 146.8, 145.8, 144.0, 125.81, 125.76, 125.7,
6
−1
1
20.0, 118.0, 114.5, 113.2, 111.8, 97.6, 64.9, 64.4, 56.9; IR (cm ): 1685
(C=O), 1637 (C=C); ES m/z (% relative abundance): 363 (M + Na, 50),
7
03 (2M + Na, 100); HRMS (ESI) calcd for C H O : 341.1025; found:
19 17 6
+
10 J.F. Cheng and Z.Q. Liu, Chem. Res. Toxicol., 2015, 228, 451.
K. Sagar, Inter. J. Pharm. Sc. Res., 2013, 4, 3296.
341.1037 (M + H ).
11
(
Z) -2-[(ferrocenyl) methylidene]naphthofuran-3(2H) -one,
12 K.N. Tiwari, J.P. Monserrat, F. de Montigny, G. Jaouen, M.N. Rager and E.
C H FeO (5a)
Hillard, Organometallics, 2011, 30, 5424.
2
3
16
2
1
3
K.N. Tiwari, J.P. Monserrat, A. Hequet, C. Ganem-Elbaz, T. Cresteil, G.
Jaouen, A. Vessières, E.A. Hillard and C. Jolivalt, Dalton Trans., 2012, 41,
Compound 5a was obtained by condensation of naphthofuran-3(2H)-one
121 mg, 0.66 mmol) and ferrocene carboxaldehyde (141 mg, 0.66 mmol),
(
6
451.
according to procedure A, with classical heating, and was purified by
flash chromatography on silica gel (eluent cyclohexane 9/ethyl acetate 1)
to afford the product as: Violet solid; yield 133 mg (53%); m.p. 205 °C;
14
J.P. Monserrat, K.N. Tiwari, L. Quentin, P. Pigeon, G. Jaouen, A. Vessières and
G.G. Chabot, J. Org. Chem., 2013, 734, 78.
D. Villemin and M. Ricard, Tetrahedron Lett., 1984, 25, 1059.
1
5
1
H NMR (400 MHz, DMSO-d ): δ 8.72 (d, 1H), 8.37 (d, 1H), 8.09 (d, 1H),
6
16 A. Ben Alloum, B. Labiad and D. Villemin, J. Chem. Soc. Chem. Comm.,
989, 386.
17 H. Zhang, X.H. Xu, Y. Cui, L.G. Xie and C.H. Kong, Pest. Manag. Sci., 2012,
8, 1512.
18 S. Anil and S.S. Chibber, J. Het. Chem., 1981, 18, 275.
19 K.F. Liew, K.L. Chan and C.Y. Lee, Eur. J. Med. Chem., 2015, 94, 195.
7
.76–7.73 (m), 7.58 (d, 1H), 6.97 (s, 1H), 4.98 (s, 2H), 4.66 (s, 2H), 4.22 (s,
1
13
5H); C NMR (400 MHz, DMSO-d ): δ 184.2, 160.0, 148.0, 133.0, 130.4,
6
1
29.4, 129.0, 128.0, 125.8, 122.0, 115.0, 113.0, 110.0, 76.1, 71.8, 71.5, 69.9;
6
−1
IR (cm ): 1685 (C=O), 1626–1488 (C=C), 1220 (C–O–C); HRMS (EI)
calcd for C H FeO : 380.0500; found: 380.0506 (M ).
+
23
16
2
2
0
Y. Kim, J. Kim, P. Jonghoon and B. Seung, Org. Lett., 2009, 11, 1117.
(
Z)-2-[(1,3-benzodioxol-5-yl)methylidene]naphthofuran-3(2H)-one,
21 A. Sonn, Ber., 1917, 50, 1262.
C H O (5b)
2
0
12
4
22 A. Sonn, Ber., 1919, 52, 923.
According to procedure A under both classical and microwave heating,
compound 5b was prepared by condensation of naphthofuran-3(2H)-
one (121 mg, 0.66 mmol) and piperonal (126 mg, 0.84 mol) to afford the
23 J.F. Cheng and Z.Q. Liu, Chem Res. Toxicol., 2015, 228, 451.
24 D. Bolek and M. Gutschow, J. Het. Chem., 2005, 42, 1399.
25 D. Villemin and A. Ben Alloum, Synthesis, 1991, 301.