Synthesis of New Hydroxy-2-styrylchromones

Article abstract of DOI:10.1002/ejoc.200300468

Hydroxy-2-styrylchromones 5a-i were prepared by debenzylation of benzyloxy-2-styrylchromones 3a-i, which were synthesised by the Baker-Venkataraman method. The last step of this method, the cyclodehydration 5-aryl-3-hydroxy-1-(2-hydroxyaryl)-2,4-pentadien

Full text of DOI:10.1002/ejoc.200300468

FULL PAPER
Synthesis of New Hydroxy-2-styrylchromones
[a]
[a]
[a]
´
Clementina M. M. Santos, Artur M. S. Silva,* and Jose A. S. Cavaleiro
Keywords: Rearrangements / Cyclizations / Protecting groups / Heterocycles
Hydroxy-2-styrylchromones 5a−i were prepared by de-
benzylation of benzyloxy-2-styrylchromones 3a−i, which ures, but the latter procedure gave benzyloxy-2-
were synthesised by the Baker−Venkataraman method. The styrylchromones 3a−i in better yields. The structures of all
mones 4a−f were obtained as by-products in both proced-
last step of this method, the cyclodehydration 5-aryl-3-hy- new compounds were established by extensive NMR studies.
droxy-1-(2-hydroxyaryl)-2,4-pentadien-1-ones 2a−i, was car-
ried out with a catalytic amount of iodine, or p-toluenesul-
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
fonic acid, in DMSO. Benzyloxy-3-cinnamoyl-2-styrylchro- Germany, 2003)
Introduction
in free radical production. Alternatively, they may act by
scavenging reactive oxygen species (e.g. superoxide anion,
peroxyl, alkoxyl, hydroxyl, and nitric oxide radicals and sin-
glet oxygen), or protecting antioxidant defences. Flavones
have been identified as fulfilling most of the necessary cri-
teria, since several structure-activity studies have shown
that the structural requirements for a strong antioxidant ac-
tivity are a C2ϭC3 double bond conjugated to a carbonyl
group at C-4, a ortho-dihydroxy substitution on ring B (a
catechol moiety) and free OH groups at the C-3 and C-
5 positions.[5,7,9,18]
Taking into consideration the important biological activi-
ties of flavones, namely, their antioxidant activity and their
similarity to 2-styrylchromones, we decided to devote some
attention to the synthesis of hydroxy-2-styrylchromones.
The diversity of the substitution pattern, including the pres-
ence of hydroxyl substituents at certain positions of the
skeleton (5, 7, 3Ј, and 4Ј) and the inherent C-4 carbonyl
group and C2ϭC3 double bond, was taken into consider-
ation, having in mind that further antioxidant structure-
activity studies would be carried out. Following our experi-
ence in the synthesis of 2-styrylchromones,[19] we report
here the synthesis of several new hydroxy- or polyhydroxy-
2-styrylchromones, starting from 2Ј-hydroxyacetophenones
and cinnamic acid-derivatives.
Chromones (1-benzopyran-4-ones) are one of the most
abundant classes of naturally occurring oxygen-
heterocycles.[1Ϫ3] The significance of these compounds is
due not only to the important biological functions they play
in Nature, but also because certain derivatives have shown
considerable pharmacological, biocidal, and antioxidant
activities;[2,4Ϫ10] some of them are being marketed as
drugs.[11] 2-Phenylchromones, also known as flavones, are
the major constituents of this class of compounds and have
a wide range of biological activities.[4Ϫ10] Other groups of
chromones, which are less widely-occurring in nature, have
also shown important biological activities. For example, for
the newly-discovered group of 2-styrylchromones, only two
natural derivatives have been found, but they have shown
potent in vitro cytotoxicity against human leukaemia
cells.[12] Prior to the isolation of these natural 2-styrylchro-
mones, studies had already been carried out on numerous
synthetic derivatives,[13] which also showed promising anti-
tumour and anti-allergic activities.[14] More recently, it has
been demonstrated that certain synthetic derivatives are in-
hibitors of the replication of both 1B and 14 serotypes of
the human anti-rhinovirus,[15] while we have found that 3Ј-
allyl-5,7,4Ј-trimethoxy-2-styrylchromone uncouples oxidat-
ive phosphorylation,[16] and that some hydroxy-2-styryl-
chromones act as potent xanthine oxidase inhibitors.[17]
The mechanism of action of polyphenolic compounds as
antioxidants can include the suppression of the formation
of reactive oxygen species, either by the inhibition of en-
zymes (e.g. xanthine oxidase and proteine kinase C) or the
chelation of trace metal ions (e.g. Fe2ϩ or Cuϩ) involved
Results and Discussion
Chemistry
Benzyloxy-2-styrylchromones 3aϪi were prepared in
good overall yields according to the three-step sequence
shown in Scheme 1.[20] For this purpose, benzyloxy-2Ј-
cinnamoyloxyacetophenones 1 were obtained from the re-
action of the 2Ј-hydroxyacetophenone derivatives with the
appropriate cinnamoyl chloride, commercially available in
[a]
Department of Chemistry, University of Aveiro,
3810-193 Aveiro, Portugal
Fax: (internat.) ϩ 351-234-370084
E-mail: arturs@dq.ua.pt
Eur. J. Org. Chem. 2003, 4575Ϫ4585
DOI: 10.1002/ejoc.200300468
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4575

C. M. M. Santos, A. M. S. Silva, J. A. S. Cavaleiro
FULL PAPER
the cases of 1aϪc, or prepared in situ from the cinnamic this could be followed by a retro-aldol-type reaction leading
acids and phosphoryl chloride for 1dϪi. The to the 2-hydroxyacetophenone starting materials and the
BakerϪVenkataraman rearrangement of compounds 1aϪi cinnamic acid-derivatives. This last proposal may explain
into
5-aryl-3-hydroxy-1-(2-hydroxyaryl)-2,4-pentadien-1- the formation of such a large amount of the 2Ј-benzyloxy-
ones 2aϪi was carried out by their treatment with an excess 6Ј-hydroxyacetophenone starting material.
of potassium hydroxide (powder) in DMSO. Cyclodehy-
dration of ketone 2a with a mixture of DMSO and a cata-
lytic amount of iodine, at 90 °C[21] led to the desired 7-
benzyloxy-2-styrylchromone 3a in good yield (74 %). How-
ever, treatment of the intermediate 2b under the same reac-
tion conditions led to the formation of 5-benzyloxy-3-cin-
namoyl-2-styrylchromone 4b (9 %) and the starting mate-
rial 2Ј-benzyloxy-6Ј-hydroxyacetophenone (65 %), but the
expected 5-benzyloxy-2-styrylchromone 3b was not ob-
tained. A plausible mechanism for the formation of these
two compounds is depicted in Scheme 2. In the reaction
medium, the structures involved in the keto-enol equilib-
rium may give rise to compound 6b by reaction with
DMSO.[22] This compound can then react with 2b, leading
to the dimer 7b. A retro-aldol-type reaction of 7b could
then give the starting 2Ј-benzyloxy-6Ј-hydroxyaceto-
phenone and the triketo derivative 8b, which could then
cyclodehydrate to give the 5-benzyloxy-3-cinnamoyl-2-styr-
ylchromone 4b. Since we didn’t use dry DMSO, compounds
6 could also react with water at their enolic carbon, and
Scheme 2
Cyclodehydration of ketones 2cϪi under the same reac-
tion conditions (i.e. a mixture of DMSO and a catalytic
amount of iodine at 90 °C) led to the desired 2-styryl-
chromones 3cϪi in poor yields, contaminated in several
cases by the corresponding 3-cinnamoyl-2-styrylchromones
4cϪf and the starting 2Ј-hydroxyacetophenones. The
amount of the latter compounds was higher when the yields
of 2-styrylchromone derivatives 3cϪi and 4cϪi were low.
Since the yields we obtained of 3cϪi were not acceptable,
we tried the cyclodehydration of ketones 2aϪi with p-tolu-
enesulfonic acid in DMSO, at 90 °C.[23] In general, the de-
sired benzyloxy-2-styrylchromones 3aϪi were obtained in
better yields, but the by-products 3-cinnamoyl-2-styrylchro-
mones 4a,c were also obtained in some cases. These results
seem to indicate that the cyclodehydration of 2aϪi is
favourable in the acidic medium.
Debenzylation of benzyloxy-2-styrylchromones 3aϪi was
achieved by their treatment with a solution of hydrogen
bromide in acetic acid at reflux, to give the corresponding
hydroxy-2-styrylchromones 5aϪi in moderate yields.
NMR Spectroscopy
1
The most noticeable features of the H and 13C NMR
spectra of 2Ј-cinnamoyloxyacetophenones 1aϪi are: i) the
resonances of the 2-CH3 proton and carbon atoms, which
appear at δ ϭ 2.47Ϫ2.53 and 29.5Ϫ32.0 ppm, respectively;
ii) the resonances of the benzylic methylenic proton and
carbon atoms, which appear at δ ϭ 4.93Ϫ5.21 and
70.0Ϫ71.2 ppm, respectively; iii) the pair of doublets corre-
Scheme 1
4576
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Synthesis of New Hydroxy-2-styrylchromones
FULL PAPER
sponding to the resonances of the Hα (δ ϭ 6.37Ϫ6.69 ppm)
and Hβ (δ ϭ 7.71Ϫ7.91 ppm) protons; the corresponding
coupling constant, JHα-Hβ ഠ 16 Hz, indicates the presence
of a trans configuration of this double bond; iv) the ester
and ketone carbonyl groups’ resonances, which appear at
δ ϭ 165.0Ϫ165.4 and 195.6Ϫ200.7 ppm, respectively. It is
important to notice that the resonance of the ketone car-
bonyl group of 4Ј-benzyloxy-2Ј-cinnamoyloxyaceto-
Figure 1. Main connectivities found in the HMBC spectra of com-
phenones 1a,d,g appears at δ ϭ 195.6Ϫ195.8 ppm while pounds 2aϪi and 4aϪi
those also bearing a 6Ј-benzyloxy group 1b,c,e,f,h,i appear
at δ ϭ 200.5Ϫ200.7 ppm. This deshielding effect is due to
the lack of conjugation between this carbonyl group and
The 1H NMR spectra of hydroxy-2-styrylchromones
the aryl ring of the acetophenone, caused by the steric clash 5aϪi revealed the presence of hydroxyl proton resonances
between the two ortho-substituents and the acetyl group.
at δ ഠ 10 ppm, assigned to 7,3Ј,4Ј-OH groups, and at δ ഠ
1
In the H NMR spectra of each one of 5-aryl-3-hydroxy- 13 ppm, attributed to the 5-OH group. The higher fre-
1-(2-hydroxyaryl)-2,4-pentadien-1-ones 2aϪi, there are two quency value of the latter is due to the intramolecular hy-
signals, at δ ϭ 12.68Ϫ13.73 and 14.46Ϫ14.77 ppm, which drogen bond of the 5-hydroxy group to the carbonyl group.
are due to protons involved in hydrogen bonding. One can
The assignments of the carbon resonances of all com-
conclude that these compounds 2aϪi exist in their enolic pounds 1aϪi, 2aϪi, 3aϪi, 4aϪf, and 5aϪi were made by
forms, as shown in Scheme 1, with the former signals corre- analysis of their HSQC and HMBC spectra. Figure 1 shows
sponding to the resonances of the phenolic protons, and the some of the main long-range connectivities found in the
latter ones being due to the 3-OH protons. The resonance HMBC spectra of 5-aryl-3-hydroxy-1-(2-hydroxyaryl)-2,4-
of 3-OH appears, in most cases, as a doublet, due to the pentadien-1-ones 2aϪi.
long-range coupling with 4-H (JH4-3OH ഠ 0.6Ϫ1.2 Hz).
From the values of the vicinal coupling constants (3J4H-
5H ഠ 16 Hz), it was possible to establish the trans configura-
Conclusion
tion of these two protons.
An important feature of the H NMR spectra of 2-styr-
1
We have prepared several hydroxy-2-styrylchromones
5aϪi by acidic debenzylation of the corresponding benzyl-
oxy-2-styrylchromones 3aϪi, which were synthesised by the
BakerϪVenkataraman method. The cyclodehydration reac-
tion of the intermediates 5-aryl-3-hydroxy-1-(2-hydroxy-
aryl)-2,4-pentadien-1-ones 2aϪi to give the corresponding
benzyloxy-2-styrylchromones 3aϪi was studied. Better re-
sults were obtained when the cyclodehydration was carried
out with p-toluenesulfonic acid in DMSO than with a cata-
lytic amount of iodine in DMSO. In both procedures,
benzyloxy-3-cinnamoyl-2-styrylchromones 4aϪf were ob-
tained as by-products.
ylchromones 3aϪi and 5aϪi is the singlet at δ ϭ
6.13Ϫ6.47 ppm, corresponding to the resonances of 3-H;
this resonance is absent in the spectra of the 3-cinnamoyl-
2-styrylchromones 4aϪf. The analysis of the 13C NMR
spectra of compounds 3aϪi and 5aϪi revealed the reson-
ance of C-3 at δ ϭ 106.8Ϫ112.2 ppm, while in the cases of
4aϪf it appeared at δ ϭ 122.2Ϫ123.7 ppm. This deshielding
effect is due to the presence of 3-cinnamoyl substituents in
the cases of chromones 4aϪf. In the spectra of all these
chromones 3aϪi, 4aϪf and 5aϪi, the resonances assigned
to β-Η (δ
ϭ
7.36Ϫ7.74 ppm) and C-β (δ
ϭ
136.1Ϫ139.1 ppm) appeared at higher frequency values
than that of α-Η (δ ϭ 6.50Ϫ7.18 ppm) and C-α (δ ϭ
115.5Ϫ120.7 ppm), due to the mesomeric deshielding effect
of the carbonyl group. In the NMR spectra of compounds
4aϪf, one can also observe the resonances of the other vi-
nylic moiety, αЈ-H (δ ϭ 7.11Ϫ7.26 ppm), βЈ-H (δ ϭ
7.58Ϫ7.69 ppm), C-αЈ (δ ϭ 125.8Ϫ128.0 ppm), and C-βЈ
(δ ϭ 144.1Ϫ144.2 ppm). The coupling constant values,
Experimental Section
General Remarks: Melting points were measured in a Reichert
Thermovar apparatus fitted with a microscope and are uncor-
rected. NMR spectra were recorded on a Bruker DRX 300 spec-
trometer (300.13 for 1H and 75.47 MHz for 13C), with CDCl3 as
solvent, unless otherwise stated. Chemical shifts (δ) are reported in
3JHα-Hβ ഠ 16 Hz, of all the chromones we synthesised 3aϪi, ppm, and coupling constants (J) in Hz. The internal standard was
TMS. Unequivocal 13C assignments were made with the aid of 2D
3
4aϪf and 5aϪi and also JHαЈ-HβЈ ഠ 16 Hz for 4aϪi, indi-
gHSQC and gHMBC (delays for one bond and long-range J C/H
cate a trans-configuration of these CαϭCβ and CαЈϭCβЈ
couplings were optimised for 145 and 7 Hz, respectively) experi-
double bonds.
ments. Electron impact (EI, 70 eV) MS were recorded on VG Auto-
The assignments of each AB spin-system, corresponding
spec Q and M spectrometers. Elemental Analyses were obtained
to the resonances of α-Η/β-Η and αЈ-H/βЈ-H of chromones
with a CHNS 932 Leco analyser (University of Aveiro). Preparative
thin-layer chromatography was performed with Merck silica gel 60
DGF254. Column chromatography was performed with Merck sil-
ica gel 60, 70Ϫ230 mesh. All other chemicals and solvents used
were obtained from commercial sources and used as received or
dried using standard procedures.
4aϪi, was made on the basis of the connectivities found in
˜
the HMBC spectra. The resonance assigned to β-Η corre-
lates with the signals of C-2Ј, C-6Ј, and C-2, whereas that
ascribed to βЈ-H correlates with C-2ЈЈ, C-6ЈЈ, and CϭO of
the cinnamoyl group (Figure 1).
Eur. J. Org. Chem. 2003, 4575Ϫ4585
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C. M. M. Santos, A. M. S. Silva, J. A. S. Cavaleiro
FULL PAPER
Synthesis of 2Ј-(Cinnamoyloxy)acetophenones 1a؊i. Method 1: Cin-
namoyl chloride (1.9 g, 11.4 mmol) was added to a solution of the
appropriate acetophenone (5.7 mmol) in dry pyridine (150 mL).
The solution was stirred under nitrogen at room temperature for
12 hours. After that period, the solution was poured into ice and
water (100 mL), and the pH adjusted to 4 with dilute hydrochloric
acid. The mixture was extracted with chloroform (2 ϫ 100 mL),
Method 2: The appropriate cinnamic acid (9.5 mmol) and phos-
phorus oxychloride (4.0 mL, 43.0 mmol) were added to a solution
of the appropriate acetophenone (8.6 mmol) in dry pyridine
(170 mL). The solution was stirred under different conditions of
time and temperature according to the substitution of the com-
pound: 1d and 1e, 60 °C, 24 h; 1f, room temperature, 24 h; 1g and
1h, 60 °C, 4 h; 1i, room temperature, 1 h. After that, the solution
and the organic layer washed with water. The solvent was evapo- was poured into ice and water (100 mL), and the pH adjusted to 4
rated to dryness, and the residue was purified by silica gel column
chromatography using a (3:7) mixture of light petroleum:dichloro-
methane as eluent. The solvent was evaporated to dryness in each
case, and the residue was crystallised from ethanol to give the ex-
pected 2Ј-cinnamoyloxyacetophenones 1aϪc.
with hydrochloric acid. The mixture was extracted with chloroform
(100 mL), and the organic layer washed with water. The solvent
was evaporated, and the residue was purified by silica gel column
chromatography using a mixture of light petroleum:dichlorome-
thane (3:7) as eluent. The solvent was evaporated to dryness in
each case, and the residue was crystallised from ethanol to give the
expected cinnamoyloxyacetophenones 1dϪi.
4Ј-Benzyloxy-2Ј-(cinnamoyloxy)acetophenone (1a): Yield 84.9 %
(1.80 g). M.p. 118Ϫ119 °C (recrystallised from ethanol). 1H NMR:
δ ϭ 2.53 (s, 3 H, 2-CH3), 5.12 (s, 2 H, 4Ј-OCH2C6H5,), 6.69 (d,
J ϭ 16.0 Hz, 1 H, α-H), 6.78 (br. s, 1 H, 3Ј-H), 6.92 (dd, J ϭ 8.8,
2.4 Hz, 1 H, 5Ј-H), 7.35Ϫ7.44 (m, 8 H, 3ЈЈ,4ЈЈ,5ЈЈ-H and 2,3,4,5,6-
H of 4Ј-OCH2C6H5), 7.61 (dd, J ϭ 6.5, 2.1 Hz, 2 H, 2ЈЈ,6ЈЈ-H),
7.88 (d, J ϭ 8.8 Hz, 1 H, 6Ј-H), 7.91 (d, J ϭ 16.0 Hz, 1 H, β-H)
ppm. 13C NMR: δ ϭ 29.5 (C-2), 70.4 (4Ј-OCH2C6H5), 110.0 (C-
3Ј), 112.5 (C-5Ј), 116.8 (C-α), 123.8 (C-1Ј), 127.5 (C-2,6 of 4Ј-
OCH2C6H5), 128.3 (C-4 of 4Ј-OCH2C6H5), 128.4 (C-2ЈЈ,6ЈЈ), 128.7
(C-3,5 of 4Ј-OCH2C6H5), 128.9 (C-3ЈЈ,5ЈЈ), 130.8 (C-4ЈЈ), 132.3 (C-
6Ј), 134.0 (C-1ЈЈ), 135.7 (C-1 of 4Ј-OCH2C6H5), 147.3 (C-β), 151.3
(C-2Ј), 162.8 (C-4Ј), 165.1 (CϭO), 195.8 (C-1) ppm. EI-MS: m/z
(rel. int.) ϭ 372 (8) [Mϩ·], 281 (2), 242 (1), 239 (2), 192 (1), 181 (2),
131 (100), 103 (32), 91 (43). C24H20O4 (372.4): calcd. C 77.40, H
5.41; found C 77.48, H 5.51.
4Ј-Benzyloxy-2Ј-(4-benzyloxycinnamoyloxy)acetophenone
(1d):
Yield 86.1 % (3.54 g). M.p. 197Ϫ200 °C (recrystallised from etha-
1
nol). H NMR: δ ϭ 2.52 (s, 3 H, 2-CH3), 5.11 and 5.12 (2s, 4 H,
4Ј,4ЈЈ-OCH2C6H5), 6.55 (d, J ϭ 16.0 Hz, 1 H, α-H), 6.77 (d, J ϭ
2.4 Hz, 1 H, 3Ј-H), 6.91 (dd, J ϭ 8.8, 2.4 Hz, 1 H, 5Ј-H), 7.01 (d,
J ϭ 8.7 Hz, 2 H, 3ЈЈ,5ЈЈ-H), 7.35Ϫ7.46 (m, 10 H, 2,3,4,5,6-H of
4Ј,4ЈЈ-OCH2C6H5), 7.55 (d, J ϭ 8.7 Hz, 2 H, 2ЈЈ,6ЈЈ-H), 7.86 (d,
J ϭ 8.8 Hz, 1 H, 6Ј-H), 7.87 (d, J ϭ 16.0 Hz, 1 H, β-H) ppm. 13C
NMR: δ ϭ 29.7 (C-2), 70.1 (4Ј,4ЈЈ-OCH2C6H5), 109.9 (C-3Ј), 112.5
(C-5Ј), 114.3 (C-α), 115.3 (C-3ЈЈ,5ЈЈ), 123.9 (C-1Ј), 127.0 (C-1ЈЈ),
127.5 and 127.6 (C-2,6 of 4Ј,4ЈЈ-OCH2C6H5), 128.2 and 128.3 (C-
4
of 4Ј,4ЈЈ-OCH2C6H5), 128.7 and 128.7 (C-3,5 of 4Ј,4ЈЈ-
OCH2C6H5), 130.2 (C-2ЈЈ,6ЈЈ), 132.2 (C-6Ј), 135.8 and 136.3 (C-1
of 4Ј,4ЈЈ-OCH2C6H5), 147.0 (C-β), 151.5 (C-2Ј), 161.0 (C-4ЈЈ),
162.8 (C-4Ј), 165.4 (CϭO), 195.9 (C-1) ppm. EI-MS: m/z (rel.
int.) ϭ 478 (0.2) [Mϩ·], 372 (0.3), 281 (0.4), 267 (0.2), 254 (12), 237
(11), 224 (2), 131 (31), 103 (7), 91 (100). C31H26O5 (478.5): calcd.
C 77.81, H 5.48; found C 77.72, H 5.51.
6Ј-Benzyloxy-2Ј-(cinnamoyloxy)acetophenone (1b): Yield 85.4 %
(1.81 g). M.p. 90Ϫ93 °C (recrystallised from ethanol). 1H NMR:
δ ϭ 2.53 (s, 3 H, 2-CH3), 5.11 (s, 2 H, 6Ј-OCH2C6H5), 6.58 (d, J ϭ
16.0 Hz, 1 H, α-H), 6.82 (d, J ϭ 8.2 Hz, 1 H, 3Ј-H), 6.89 (d, J ϭ
8.2 Hz, 1 H, 5Ј-H), 7.31Ϫ7.42 (m, 9 H, 4Ј-H, 3ЈЈ,4ЈЈ,5ЈЈ-H and
2,3,4,5,6-H of 6Ј-OCH2C6H5), 7.54Ϫ7.57 (m, 2 H, 2ЈЈ,6ЈЈ-H), 7.83
(d, J ϭ 16.0 Hz, 1 H, β-H) ppm. 13C NMR: δ ϭ 31.7 (C-2), 70.8
(6Ј-OCH2C6H5), 109.9 (C-5Ј), 115.4 (C-3Ј), 116.5 (C-α), 124.9 (C-
1Ј), 127.2 (C-2,6 of 6Ј-OCH2C6H5), 128.1 (C-4 of 6Ј-OCH2C6H5),
128.3 (C-2ЈЈ,6ЈЈ), 128.6 (C-3,5 of 6Ј-OCH2C6H5), 129.1 (C-3ЈЈ,5ЈЈ),
130.7 (C-4ЈЈ), 130.9 (C-4Ј), 133.9 (C-1ЈЈ), 136.0 (C-1 of 6Ј-
OCH2C6H5), 147.1 (C-β), 147.6 (C-2Ј), 156.4 (C-6Ј), 165.0 (CϭO),
200.6 (C-1) ppm. EI-MS: m/z (rel. int.) ϭ 372 (2) [Mϩ·], 281 (2),
267 (1), 241 (10), 224 (12), 191 (3), 131 (100), 103 (32), 91 (55).
C24H20O4 (372.4): calcd. C 77.40, H 5.41; found C 77.31, H 5.49.
6Ј-Benzyloxy-2Ј-(4-benzyloxycinnamoyloxy)acetophenone
(1e):
Yield 88.1 % (3.62 g). M.p. 133Ϫ134 °C (recrystallised from etha-
nol). 1H NMR: δ ϭ 2.52 (s, 3 H, 2-CH3), 5.11 (s, 2 H, 4ЈЈ-
OCH2C6H5), 5.13 (s, 2 H, 6Ј-OCH2C6H5), 6.44 (d, J ϭ 15.9 Hz, 1
H, α-H), 6.81 (d, J ϭ 8.2 Hz, 1 H, 3Ј-H), 6.89 (d, J ϭ 8.2 Hz, 1 H,
5Ј-H), 6.99 (d, J ϭ 8.7 Hz, 2 H, 3ЈЈ,5ЈЈ-H), 7.32Ϫ7.45 (m, 11 H,
4Ј-H and 2,3,4,5,6-H of 6Ј,4ЈЈ-OCH2C6H5), 7.52 (d, J ϭ 8.7 Hz, 2
H, 2ЈЈ,6ЈЈ-H), 7.79 (d, J ϭ 15.9 Hz, 1 H, β-H) ppm. 13C NMR: δ ϭ
31.8 (C-2), 70.1 (4ЈЈ-OCH2C6H5), 70.8 (6Ј-OCH2C6H5), 109.9 (C-
5Ј), 114.1 (C-α), 115.2 (C-3ЈЈ,5ЈЈ), 115.5 (C-3Ј), 125.0 (C-1Ј), 127.0
(C-1ЈЈ), 127.3 and 127.5 (C-2,6 of 6Ј,4ЈЈ-OCH2C6H5), 128.2 (C-4 of
6Ј,4ЈЈ-OCH2C6H5), 128.6 (C-3,5 of 6Ј,4ЈЈ-OCH2C6H5), 130.2 (C-
2ЈЈ,6ЈЈ), 130.8 (C-4Ј), 136.0 and 136.3 (C-1 of 6Ј,4ЈЈ-OCH2C6H5),
146.8 (C-β), 147.8 (C-2Ј), 156.4 (C-6Ј), 160.9 (C-4ЈЈ), 165.4 (CϭO),
200.7 (C-1) ppm. EI-MS: m/z (rel. int.) ϭ 478 (7) [Mϩ·], 435 (0.5),
387 (0.5), 345 (0.5), 298 (0.5), 254 (0.5), 237 (86), 146 (5), 91 (100).
C31H26O5 (478.5): calcd. C 77.81, H 5.48; found C 77.80, H 5.52.
4Ј,6Ј-Dibenzyloxy-2Ј-(cinnamoyloxy)acetophenone
(1c):
Yield
95.1 % (2.59 g). M.p. 104Ϫ105 °C (recrystallised from ethanol). 1H
NMR: δ ϭ 2.49 (s, 3 H, 2-CH3), 5.04 and 5.08 (2s, 4 H, 4Ј,6Ј-
OCH2C6H5), 6.42 (d, J ϭ 2.2 Hz, 1 H, 3Ј-H), 6.53 (d, J ϭ 2.2 Hz,
1 H, 5Ј-H), 6.59 (d, J ϭ 16.0 Hz, 1 H, α-H), 7.35Ϫ7.42 (m, 8 H,
3ЈЈ,4ЈЈ,5ЈЈ-H and 2,3,4,5,6-H of 4Ј,6Ј-OCH2C6H5), 7.56Ϫ7.59 (m,
2 H, 2ЈЈ,6ЈЈ-H), 7.84 (d, J ϭ 16.0 Hz, 1 H, β-H) ppm. 13C NMR:
δ ϭ 32.0 (C-2), 70.4 and 70.9 (4Ј,6Ј-OCH2C6H5), 98.4 (C-5Ј), 101.2
4Ј,6Ј-Dibenzyloxy-2Ј-(4-benzyloxycinnamoyloxy)acetophenone (1f):
Yield 89.0 % (4.47 g). M.p. 129Ϫ130 °C (recrystallised from etha-
1
nol). H NMR: δ ϭ 2.49 (s, 3 H, 2-CH3), 5.04, 5.08, and 5.11 (3s,
(C-3Ј), 116.7 (C-α), 117.9 (C-1Ј), 127.4 and 127.6 (C-2,6 of 4Ј,6Ј- 6 H, 4Ј,6Ј,4ЈЈ-OCH2C6H5), 6.42 (d, J ϭ 2.1 Hz, 1 H, 3Ј-H), 6.44
OCH2C6H5), 128.3 and 128.3 (C-4 of 4Ј,6Ј-OCH2C6H5), 128.4 (C- (d, J ϭ 16.0 Hz, 1 H, α-H), 6.52 (d, J ϭ 2.1 Hz, 1 H, 5Ј-H), 6.99
2ЈЈ,6ЈЈ), 128.7 and 128.9 (C-3,5 of 4Ј,6Ј-OCH2C6H5), 130.7 (C- (d, J ϭ 8.9 Hz, 2 H, 3ЈЈ,5ЈЈ-H), 7.34Ϫ7.46 (m, 15 H, 2,3,4,5,6-H of
3ЈЈ,4ЈЈ,5ЈЈ), 134.0 (C-1ЈЈ), 135.8 and 135.9 (C-1 of 4Ј,6Ј-
4Ј,6Ј,4ЈЈ-OCH2C6H5), 7.52 (d, J ϭ 8.9 Hz, 2 H, 2ЈЈ,6ЈЈ-H), 7.79 (d,
OCH2C6H5), 147.2 (C-β), 149.5 (C-2Ј), 158.1 (C-6Ј), 161.2 (C-4Ј), J ϭ 16.0 Hz, 1 H, β-H) ppm. 13C NMR: δ ϭ 32.0 (C-2), 70.0, 70.4,
165.2 (CϭO), 199.5 (C-1) ppm. EI-MS: m/z (rel. int.) ϭ 478 (4)
and 70.9 (4Ј,6Ј,4ЈЈ-OCH2C6H5), 98.3 (C-5Ј), 101.2 (C-3Ј), 114.2 (C-
[Mϩ·], 435 (2), 387 (6), 373 (1), 347 (9), 345 (15), 330 (4), 181 (2), α), 115.2 (C-3ЈЈ,5ЈЈ), 118.0 (C-1Ј), 127.0 (C-1ЈЈ), 127.4, 127.5, and
131 (100), 103 (20), 91 (53). C31H26O5 (478.5): calcd. C 77.81, H 127.6 (C-2,6 of 4Ј,6Ј,4ЈЈ-OCH2C6H5), 128.2 and 128.3 (C-4 of
5.48; found C 77.94, H 5.42.
4Ј,6Ј,4ЈЈ-OCH2C6H5), 128.7 (C-3,5 of 4Ј,6Ј,4ЈЈ-OCH2C6H5), 130.2
4578
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Org. Chem. 2003, 4575Ϫ4585

Synthesis of New Hydroxy-2-styrylchromones
FULL PAPER
(C-2ЈЈ,6ЈЈ), 135.8, 135.9, and 136.3 (C-1 of 4Ј,6Ј,4ЈЈ-OCH2C6H5), (C-4ЈЈ), 157.8 (C-6Ј), 161.0 (C-4Ј), 165.1 (CϭO), 199.4 (C-1) ppm.
146.8 (C-β), 149.5 (C-2Ј), 158.0 (C-6Ј), 160.1 (C-4Ј), 161.1 (C-4ЈЈ), EI-MS: m/z (rel. int.) ϭ 690 (1) [Mϩ·], 360 (1), 343 (18), 306 (2),
165.4 (CϭO), 199.6 (C-1) ppm. EI-MS: m/z (rel. int.) ϭ 584 (2)
[Mϩ·], 541 (3), 493 (2), 451 (2), 400 (1), 348 (2), 345 (3), 257 (1),
237 (63), 181 (2), 147 (3), 91 (100). C38H32O6 (584.7): calcd. C
78.06, H 5.52; found C 78.13, H 5.49.
253 (2), 180 (8), 173 (7), 160 (8), 146 (5), 117 (2), 91 (100).
C45H38O7 (690.8): calcd. C 78.24, H 5.54; found C 78.26, H 5.53.
Synthesis of 5-Aryl-3-hydroxy-1-(2-hydroxyaryl)-2,4-pentadien-1-
ones 2a؊i: Potassium hydroxide (powder, 1.0 g, 25 mmol) was ad-
ded to a solution of the appropriate 2Ј-cinnamoyloyacetophenone
1aϪi (5 mmol) in dimethyl sulfoxide (30 mL). The solution was
stirred under nitrogen at room temperature for 2 hours. After that
period, the solution was poured into ice and water (200 mL), and
the pH adjusted to 4 with dilute hydrochloric acid. The solid so-
obtained was removed by filtration, dissolved in dichloromethane
(20 mL), and purified by silica gel column chromatography using
dichloromethane as eluent. The solvent was evaporated to dryness
in each case, and the residue was crystallised from ethanol to give
the expected products 2aϪi.
4Ј-Benzyloxy-2Ј-(3,4-dibenzyloxycinnamoyloxy)acetophenone (1g):
Yield 84.0 % (4.22 g). M.p. 127Ϫ128 °C (recrystallised from etha-
nol). 1H NMR: δ ϭ 2.51 (s, 3 H, 2-CH3), 5.09 (s, 2 H, 4Ј-
OCH2C6H5), 5.19 and 5.21 (2s, 4 H, 3ЈЈ,4ЈЈ-OCH2C6H5), 6.47 (d,
J ϭ 15.9 Hz, 1 H, α-H), 6.76 (d, J ϭ 2.2 Hz, 1 H, 3Ј-H), 6.90 (dd,
J ϭ 8.7, 2.2 Hz, 1 H, 5Ј-H), 6.93 (d, J ϭ 8.2 Hz, 1 H, 5ЈЈ-H), 7.13
(dd, J ϭ 8.2, 1.8 Hz, 1 H, 6ЈЈ-H), 7.19 (d, J ϭ 1.8 Hz, 1 H, 2ЈЈ-H),
7.24Ϫ7.48 (m, 15 H, 2,3,4,5,6-H of 4Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 7.78 (d,
J ϭ 15.9 Hz, 1 H, β-H), 7.86 (d, J ϭ 8.7 Hz, 1 H, 6Ј-H) ppm. 13C
NMR: δ ϭ 29.6 (C-2), 70.3 (4Ј-OCH2C6H5), 70.8 and 71.2 (3ЈЈ,4ЈЈ-
OCH2C6H5), 109.9 (C-3Ј), 112.4 (C-5Ј), 113.7 (C-2ЈЈ), 114.0 (C-
5ЈЈ), 114.5 (C-α), 123.5 (C-6ЈЈ), 123.8 (C-1Ј), 127.1 and 127.2 (C-
2,6 of 4Ј,6Ј,4ЈЈ-OCH2C6H5), 127.3 (C-1ЈЈ), 127.5, 127.9, and 128.3
(C-4 of 4Ј,6Ј,4ЈЈ-OCH2C6H5), 128.5 and 128.6 (C-3,5 of 4Ј,6Ј,4ЈЈ-
OCH2C6H5), 132.2 (C-6Ј), 135.7 (C-1 of 4Ј-OCH2C6H5), 136.5 and
136.7 (C-1 of 3ЈЈ,4ЈЈ-OCH2C6H5), 147.1 (C-β), 148.8 (C-3ЈЈ), 151.4
(C-2Ј,4ЈЈ), 162.7 (C-4Ј), 165.3 (CϭO), 195.9 (C-1) ppm. EI-MS: m/
z (rel. int.) ϭ 584 (4) [Mϩ·], 360 (2), 343 (31), 251 (3), 242 (9), 181
(11), 131 (3), 106 (11), 91 (100). C38H32O6 (584.7): calcd. C 78.06,
H 5.52; found C 77.94, H 5.64.
1-(4-Benzyloxy-2-hydroxyphenyl)-3-hydroxy-5-phenyl-2,4-penta-
dien-1-one (2a): Yield 66.1 % (1.23 g). M.p. 168Ϫ169 °C (recrystal-
lised from ethanol). 1H NMR: δ ϭ 5.09 (s, 2 H, 4Ј-OCH2C6H5),
6.20 (s, 1 H, 2-H), 6.52 (br. s, 1 H, 3Ј-H), 6.54 (d, J ϭ 8.3 Hz, 1 H,
5Ј-H), 6.57 (dd, J ϭ 16.1, 0.8 Hz, 1 H, 4-H), 7.34Ϫ7.44 (m, 8 H,
3ЈЈ,4ЈЈ,5ЈЈ-H and 2,3,4,5,6-H of 4Ј-OCH2C6H5), 7.55 (dd, J ϭ 7.6,
1.8 Hz, 2 H, 2ЈЈ,6ЈЈ-H), 7.62 (d, J ϭ 8.3 Hz, 1 H, 6Ј-H), 7.61 (d,
J ϭ 16.1 Hz, 1 H, 5-H), 12.68 (s, 1 H, 2Ј-OH), 14.52 (d, J ϭ 0.8 Hz,
1 H, 3-OH) ppm. 13C NMR: δ ϭ 70.2 (4Ј-OCH2C6H5), 96.8 (C-2),
102.2 (C-3Ј), 108.4 (C-5Ј), 112.9 (C-1Ј), 122.3 (C-4), 127.5, 127.9,
128.3, 128.7, and 128.9 (C-3ЈЈ,4ЈЈ,5ЈЈ and C-2,3,4,5,6 of 4Ј-
OCH2C6H5), 129.9 (C-6Ј), 130.1 (C-2ЈЈ,6ЈЈ), 135.1 (C-1ЈЈ), 135.9
(C-1 of 4Ј-OCH2C6H5), 139.0 (C-5), 164.9 (C-4Ј), 165.3 (C-2Ј),
173.1 (C-3), 194.6 (C-1) ppm. EI-MS: m/z (rel. int.) ϭ 372 (56)
[Mϩ·], 354 (3), 281 (7), 227 (27), 200 (4), 144 (4), 131 (49), 103 (15),
91 (100). C24H20O4 (372.4): calcd. C 77.40, H 5.41; found C 77.35,
H 5.41.
6Ј-Benzyloxy-2Ј-(3,4-dibenzyloxycinnamoyloxy)acetophenone (1h):
Yield 69.1 % (3.47 g). Yellow oil. 1H NMR: δ ϭ 2.51 (s, 3 H, 2-
CH3), 5.05 (s,
2 H, 6Ј-OCH2C6H5), 5.14 (s, 4 H, 3ЈЈ,4ЈЈ-
OCH2C6H5), 6.37 (d, J ϭ 15.9 Hz, 1 H, α-H), 6.78 (d, J ϭ 8.2 Hz,
1 H, 3Ј-H), 6.83 (d, J ϭ 8.2 Hz, 1 H, 5Ј-H), 6.89 (d, J ϭ 8.4 Hz, 1
H, 5ЈЈ-H), 7.06 (dd, J ϭ 8.4, 1.8 Hz, 1 H, 6ЈЈ-H), 7.14 (d, J ϭ
1.8 Hz, 1 H, 2ЈЈ-H), 7.26Ϫ7.46 (m, 16 H, 4Ј-H and 2,3,4,5,6-H of
6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 7.71 (d, J ϭ 15.9 Hz, 1 H, β-H) ppm. 13C
1-(6-Benzyloxy-2-hydroxyphenyl)-3-hydroxy-5-phenyl-2,4-penta-
dien-1-one (2b): Yield 90.9 % (1.69 g). M.p. 166Ϫ168 °C (recrystal-
lised from ethanol). 1H NMR: δ ϭ 5.15 (s, 2 H, 6Ј-OCH2C6H5),
6.16 (dd, J ϭ 16.0, 1.2 Hz, 1 H, 4-H), 6.49 (dd, J ϭ 8.3, 1.0 Hz, 1
H, 3Ј-H), 6.62 (dd, J ϭ 8.3, 1.0 Hz, 1 H, 5Ј-H), 6.86 (s, 1 H, 2-H),
7.32 (t, J ϭ 8.3 Hz, 1 H, 4Ј-H), 7.48 (d, J ϭ 16.0 Hz, 1 H, 5-
H), 7.37Ϫ7.54 (m, 10 H, 2ЈЈ,3ЈЈ,4ЈЈ,5ЈЈ,6ЈЈ-H and 2,3,4,5,6-H of 2Ј-
OCH2C6H5), 12.89 (s, 1 H, 2Ј-OH), 14.63 (d, J ϭ 1.2 Hz, 1 H, 3-
OH) ppm. 13C NMR: δ ϭ 71.2 (6Ј-OCH2C6H5), 102.2 (C-2), 102.8
(C-3Ј), 110.6 (C-1Ј), 111.4 (C-5Ј), 122.8 (C-4), 127.8 (C-2ЈЈ,6ЈЈ),
128.1 (C-2,6 of 6Ј-OCH2C6H5), 128.4 (C-4 of 6Ј-OCH2C6H5), 128.7
(C-3ЈЈ,5ЈЈ), 128.8 (C-3,5 of 6Ј-OCH2C6H5), 131.8 (C-4ЈЈ), 135.0 (C-
1ЈЈ), 135.2 (C-4Ј), 136.0 (C-1 of 6Ј-OCH2C6H5), 138.8 (C-5), 159.5
(C-6Ј), 164.4 (C-2Ј), 174.1 (C-3), 195.0 (C-1) ppm. EI-MS: m/z (rel.
int.) ϭ 372 (14) [Mϩ·], 354 (22), 281 (18), 226 (15), 223 (10), 194
(10), 137 (15), 131 (63), 103 (24), 91 (100). C24H20O4 (372.4): calcd.
C 77.40, H, 5.41; found C 77.11, H 5.44.
NMR:
δ ϭ 31.6 (C-2), 70.6 (6Ј-OCH2C6H5), 71.0 (3ЈЈ,4ЈЈ-
OCH2C6H5), 109.8 (C-5Ј), 113.5 (C-2ЈЈ), 113.8 (C-5ЈЈ), 114.2 (C-α),
115.3 (C-3Ј), 123.3 (C-6ЈЈ), 124.8 (C-1Ј), 127.0 and 127.1 (C-2,6
of 6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 127.2 (C-1ЈЈ), 127.8 and 128.0 (C-4 of
6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 128.4 and 128.5 (C-3,5, of 6Ј,3ЈЈ,4ЈЈ-
OCH2C6H5), 130.7 (C-4Ј), 135.9 (C-1 of 6Ј-OCH2C6H5), 136.5 and
136.6 (C-1 of 3ЈЈ,4ЈЈ-OCH2C6H5), 146.8 (C-β), 147.6 (C-2Ј), 148.7
(C-3ЈЈ), 151.2 (C-4ЈЈ), 156.2 (C-6Ј), 165.1 (CϭO), 200.5 (C-1) ppm.
EI-MS: m/z (rel. int.) ϭ 584 (7) [Mϩ·], 343 (42), 253 (3), 251 (3),
181 (13), 91 (100). C38H32O6 (584.7): calcd. C 78.06, H 5.52; found
C 78.03, H 5.63.
4Ј,6Ј-Dibenzyloxy-2Ј-(3,4-dibenzyloxycinnamoyloxy)acetophenone
(1i): Yield 83.1 % (4.93 g). M.p. 110Ϫ111 °C (recrystallised from
ethanol). 1H NMR: δ ϭ 2.47 (s, 3 H, 2-CH3), 4.93 (s, 2 H, 6Ј-
OCH2C6H5), 4.97 (s, 2 H, 4Ј-OCH2C6H5), 5.10 and 5.14 (2s, 4 H,
3ЈЈ,4ЈЈ-OCH2C6H5), 6.38 (d, J ϭ 15.8 Hz, 1 H, α-H), 6.40 (d, J ϭ
2.1 Hz, 1 H, 3Ј-H), 6.48 (d, J ϭ 2.1 Hz, 1 H, 5Ј-H), 6.86 (d, J ϭ
8.3 Hz, 1 H, 5ЈЈ-H), 7.03 (d, J ϭ 8.3 Hz, 1 H, 6ЈЈ-H), 7.12 (br. s, 1
1-(4,6-Dibenzyloxy-2-hydroxyphenyl)-3-hydroxy-5-phenyl-2,4-
H, 2ЈЈ-H), 7.23Ϫ7.44 (m, 20 H, 2,3,4,5,6-H of 4Ј,6Ј,3ЈЈ,4ЈЈ- pentadien-1-one (2c): Yield 81.2 % (1.94 g). M.p. 134Ϫ136 °C
OCH2C6H5), 7.71 (d, J ϭ 15.8 Hz, 1 H, β-H) ppm. 13C NMR: δ ϭ (recrystallised from ethanol). 1H NMR: δ ϭ 5.08 and 5.09 (2s, 4
31.8 (C-2), 70.1 (6Ј-OCH2C6H5), 70.5 and 70.9 (3ЈЈ,4ЈЈ- H, 4Ј,6Ј-OCH2C6H5), 6.13 (dd, J ϭ 15.8, 1.1 Hz, 1 H, 4-H), 6.14
OCH2C6H5), 70.6 (4Ј-OCH2C6H5), 98.0 (C-5Ј), 101.1 (C-3Ј), 113.3 (d, J ϭ 2.5 Hz, 1 H, 5Ј-H), 6.20 (d, J ϭ 2.5 Hz, 1 H, 3Ј-H), 6.82
(C-2ЈЈ), 113.7 (C-5ЈЈ), 114.2 (C-α), 117.6 (C-1Ј), 123.2 (C-6ЈЈ),
(s, 1 H, 2-H), 7.44 (d, J ϭ 15.8 Hz, 1 H, 5-H), 7.37Ϫ7.51 (m, 15
126.9, 127.0 and 127.2 (C-2,6 of 4Ј,6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 127.1 H, 2ЈЈ,3ЈЈ,4ЈЈ,5ЈЈ6ЈЈ-H and 2,3,4,5,6-H of 4Ј,6Ј-OCH2C6H5), 13.69
(C-1ЈЈ), 127.4 and 127.7 (C-4 of 4Ј,6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 128.0, (s, 1 H, 2Ј-OH), 14.46 (d, J ϭ 1.1 Hz, 1 H, 3-OH) ppm. 13C NMR:
128.0, 128.3, and 128.4 (C-3,5 of 4Ј,6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 135.6 δ ϭ 70.2 and 71.2 (4Ј,6Ј-OCH2C6H5), 92.9 (C-5Ј), 95.2 (C-3Ј), 103.4
and 135.7 (C-1 of 4Ј,6Ј-OCH2C6H5), 136.4 and 136.6 (C-1 of
(C-2), 104.9 (C-1Ј), 123.1 (C-4), 127.7 and 127.7 (C-2,6 of 4Ј,6Ј-
3ЈЈ,4ЈЈ-OCH2C6H5), 146.7 (C-β), 148.6 (C-3ЈЈ), 149.3 (C-2Ј), 151.1 OCH2C6H5), 128.2 (C-2ЈЈ,6ЈЈ), 128.4 and 128.5 (C-4ЈЈ and C-4 of
Eur. J. Org. Chem. 2003, 4575Ϫ4585
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4579

C. M. M. Santos, A. M. S. Silva, J. A. S. Cavaleiro
FULL PAPER
6Ј-OCH2C6H5), 128.7, 128.8 and 128.9 (C-3ЈЈ,5ЈЈ and C-3,5 of (1), 306 (3), 268 (1), 252 (1), 243 (1), 237 (5), 215 (1), 181 (2), 147
4Ј,6Ј-OCH2C6H5), 129.6 (C-4 of 4Ј-OCH2C6H5), 135.3 (C-1ЈЈ), (4), 133 (2), 121 (3), 107 (1), 105 (2), 91 (100). C38H32O6 (584.7):
135.8 and 135.9 (C-1 of 4Ј,6Ј-OCH2C6H5), 137.9 (C-5), 161.0 (C-
6Ј), 164.6 (C-4Ј), 167.3 (C-2Ј), 172.9 (C-3), 193.8 (C-1) ppm. EI-
MS: m/z (rel. int.) ϭ 478 (9) [Mϩ·], 461 (9), 460 (14), 387 (11), 371
(7), 345 (1), 333 (5), 329 (6), 306 (6), 243 (8), 131 (35), 103 (13), 91
(100). C31H26O5 (478.5): calcd. C 77.81, H 5.48; found C 77.51,
H 5.36.
calcd. C 78.06, H 5.52; found C 78.02, H 5.53.
1-(4-Benzyloxy-2-hydroxyphenyl)-5-(3,4-dibenzyloxyphenyl)-3-
hydroxy-2,4-pentadien-1-one (2g): Yield 83.9 % (2.45 g). M.p.
1
142Ϫ143 °C (recrystallised from ethanol). H NMR: δ ϭ 5.07 (s,
2 H, 4Ј-OCH2C6H5), 5.19 (s, 4 H, 3ЈЈ,4ЈЈ-OCH2C6H5), 6.14 (s, 1 H,
2-H), 6.36 (d, J ϭ 15.7 Hz, 1 H, 4-H), 6.51 (d, J ϭ 2.4 Hz, 1 H,
3Ј-H), 6.52 (d, J ϭ 6.9, 2.4 Hz, 1 H, 5Ј-H), 6.92 (d, J ϭ 8.3 Hz, 1
1-(4-Benzyloxy-2-hydroxyphenyl)-5-(4-benzyloxyphenyl)-3-hydroxy-
2,4-pentadien-1-one (2d): Yield 64.0 % (1.53 g). M.p. 171Ϫ172 °C H, 5ЈЈ-H), 7.08 (dd, J ϭ 8.3, 1.7 Hz, 1 H, 6ЈЈ-H), 7.13 (d, J ϭ
(recrystallised from ethanol). 1H NMR: δ ϭ 5.08 and 5.10 (2s, 4 1.7 Hz, 1 H, 2ЈЈ-H), 7.25Ϫ7.52 (m, 15 H, 2,3,4,5,6-H of 4Ј,3ЈЈ,4ЈЈ-
H, 4Ј,4ЈЈ-OCH2C6H5), 6.15 (s, 1 H, 2-H), 6.44 (d, J ϭ 15.8 Hz, 1
H, 4-H), 6.51 (d, J ϭ 2.3 Hz, 1 H, 3Ј-H), 6.53 (dd, J ϭ 7.4, 2.3 Hz, 1 H, 6Ј-H), 12.71 (s, 1 H, 2Ј-OH), 14.57 (s, 1 H, 3-OH) ppm. 13C
1 H, 5Ј-H), 6.99 (d, J ϭ 8.7 Hz, 1 H, 3ЈЈ,5ЈЈ-H), 7.26Ϫ7.45 (m, 10 NMR: 70.1 (4Ј-OCH2C6H5), 70.9 and 71.3 (3ЈЈ,4ЈЈ-
OCH2C6H5), 7.49 (d, J ϭ 15.7 Hz, 1 H, 5-H), 7.59 (d, J ϭ 6.9 Hz,
δ
ϭ
H, 2,3,4,5,6-H of 4Ј,4ЈЈ-OCH2C6H5), 7.49 (d, J ϭ 8.7 Hz, 2 H, OCH2C6H5), 96.3 (C-2), 102.2 (C-3Ј), 108.3 (C-5Ј), 112.9 (C-1Ј),
2ЈЈ,6ЈЈ-H), 7.57 (d, J ϭ 15.8 Hz, 1 H, 5-H), 7.61 (d, J ϭ 7.4 Hz, 1 113.6 (C-2ЈЈ), 114.3 (C-5ЈЈ), 120.3 (C-4), 122.6 (C-6ЈЈ), 127.1, 127.3,
H, 6Ј-H), 12.73 (s, 1 H, 2Ј-OH), 14.60 (s, 1 H, 3-OH) ppm. 13C
127.5, 127.9, 128.2, 128.5 and 128.7 (C-2,3,4,5,6 of 4Ј,3ЈЈ,4ЈЈ-
NMR: δ ϭ 70.0 and 70.1 (4Ј and 4ЈЈ-OCH2C6H5), 96.2 (C-2), 102.2 OCH2C6H5), 128.3 (C-1ЈЈ), 130.0 (C-6Ј), 135.9 (C-1 of 4Ј-
(C-3Ј), 108.2 (C-5Ј), 112.9 (C-1Ј), 115.2 (C-3ЈЈ,5ЈЈ), 119.9 (C-4), OCH2C6H5), 136.7 and 136.9 (C-1 of 3ЈЈ,4ЈЈ-OCH2C6H5), 138.9
127.4 and 127.5 (C-2,6 of 4Ј,4ЈЈ-OCH2C6H5), 128.1 and 128.2 (C-
(C-5), 149.0 (C-3ЈЈ), 150.8 (C-4ЈЈ), 164.8 (C-4Ј), 165.2 (C-2Ј), 173.6
4 of 4Ј,4ЈЈ-OCH2C6H5), 128.6 (C-3,5 of 4Ј,4ЈЈ-OCH2C6H5), 129.5 (C-3), 194.3 (C-1) ppm. EI-MS: m/z (rel. int.) ϭ 584 (3) [Mϩ·], 566
(C-2ЈЈ,6ЈЈ), 130.0 (C-6Ј), 130.4 (C-1ЈЈ), 135.9 and 136.4 (C-1 of (3), 475 (4), 317 (2), 227 (9), 181 (2), 91 (100). C38H32O6 (584.7):
4Ј,4ЈЈ-OCH2C6H5), 138.8 (C-5), 160.2 (C-4ЈЈ), 164.7 (C-4Ј), 165.1 calcd. C 78.06, H 5.52; found C 78.00, H 5.49.
(C-2Ј), 173.7 (C-3), 194.3 (C-1) ppm. EI-MS: m/z (rel. int.) ϭ 478
1-(6-Benzyloxy-2-hydroxyphenyl)-5-(3,4-dibenzyloxyphenyl)-3-
hydroxy-2,4-pentadien-1-one (2 h): Yield 81.2 % (2.37 g). M.p.
152Ϫ154 °C (recrystallised from ethanol). H NMR: δ ϭ 5.15, 5.17,
and 5.20 (3s, 6 H, 6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 6.02 (d, J ϭ 15.7 Hz, 1
(6) [Mϩ·], 460 (6), 251 (7), 237 (11), 227 (24), 197 (2), 147 (4), 91
(100). C31H26O5 (478.5): calcd. C 77.81, H 5.48; found C 77.51,
H 5.72.
1-(6-Benzyloxy-2-hydroxyphenyl)-5-(4-benzyloxyphenyl)-3-hydroxy-
H, 4-H), 6.49 (d, J ϭ 8.1 Hz, 1 H, 3Ј-H), 6.61 (dd, J ϭ 8.3, 0.7 Hz,
2,4-pentadien-1-one (2e): Yield 95.0 % (2.27 g). M.p. 127Ϫ128 °C 1 H, 5Ј-H), 6.84 (s, 1 H, 2-H), 6.92 (d, J ϭ 8.4 Hz, 1 H, 6ЈЈ-H),
(recrystallised from ethanol). 1H NMR: δ ϭ 5.11 and 5.15 (2s, 4 7.00 (dd, J ϭ 8.4, 1.8 Hz, 1 H, 5ЈЈ-H), 7.05 (d, J ϭ 1.8 Hz, 1 H,
H, 6Ј,4ЈЈ-OCH2C6H5), 6.05 (d, J ϭ 15.7 Hz, 1 H, 4-H), 6.49 (d, 2ЈЈ-H), 7.28Ϫ7.53 (m, 16 H, 4Ј-H and 2,3,4,5,6-H of 6Ј,3ЈЈ,4ЈЈ-
J ϭ 8.2 Hz, 1 H, 3Ј-H), 6.61 (d, J ϭ 8.2 Hz, 1 H, 5Ј-H), 6.83 (s, 1
OCH2C6H5), 7.41 (d, J ϭ 15.7 Hz, 1 H, 5-H), 12.92 (s, 1 H, 2Ј-
H, 2-H), 6.99 (d, J ϭ 8.7 H, 2 H, 3ЈЈ,5ЈЈ-H), 7.31 (t, J ϭ 8.2 Hz, 1 OH), 14.77 (s, 1 H, 3-OH) ppm. 13C NMR: δ ϭ 71.0, 71.2, and
H, 4Ј-H), 7.35Ϫ7.53 (m, 12 H, 2ЈЈ,6ЈЈ-H and 2,3,4,5,6-H of 6Ј,4ЈЈ-
OCH2C6H5), 7.46 (d, J ϭ 15.7 Hz, 1 H, 5-H), 12.91 (s, 1 H, 2Ј-
71.5 (6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 102.8 (C-3Ј), 103.6 (C-2), 110.7 (C-1Ј),
111.4 (C-5Ј), 113.8 (C-2ЈЈ), 114.3 (C-5ЈЈ), 120.8 (C-4), 122.8 (C-6ЈЈ),
OH), 14.76 (d, J ϭ 0.6 Hz, 1 H, 3-OH) ppm. 13C NMR: δ ϭ 70.0 127.2, 127.4, 128.0, 128.3, 128.6 and 128.7 (C-2,3,4,5,6 of 6Ј,3ЈЈ,4ЈЈ-
and 71.2 (6Ј,4ЈЈ-OCH2C6H5), 102.8 (C-3Ј), 103.5 (C-2), 110.6 (C-
1Ј), 111.4 (C-5Ј), 115.2 (C-3ЈЈ,5ЈЈ), 120.5 (C-4), 127.4 and 128.0 (C-
OCH2C6H5), 135.0 (C-4Ј), 136.2, 136.7, and 136.9 (C-1ЈЈ and C-1
of 6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 138.8 (C-5), 149.0 (C-3ЈЈ), 150.9 (C-4ЈЈ),
2,6 of 6Ј,4ЈЈ-OCH2C6H5), 128.1 and 128.3 (C-4 of 6Ј,4ЈЈ- 159.4 (C-6Ј), 164.3 (C-2Ј), 174.7 (C-3), 194.6 (C-1) ppm. EI-MS:
OCH2C6H5), 128.6 and 128.7 (C-3,5 of 6Ј,4ЈЈ-OCH2C6H5), 129.5 m/z (rel. int.) ϭ 584 (3) [Mϩ·], 566 (2), 493 (3), 476 (4), 385 (3), 343
(C-2ЈЈ,6ЈЈ), 130.2 (C-1ЈЈ), 135.0 (C-4Ј), 136.1 and 136.4 (C-1 of (4), 227 (6), 181 (6), 137 (8), 108 (1), 91 (100). C38H32O6 (584.7):
6Ј,4ЈЈ-OCH2C6H5), 138.6 (C-5), 159.4 (C-4ЈЈ), 160.2 (C-6Ј), 164.3 calcd. C 78.06, H 5.52; found C 78.04, H 5.50.
(C-2Ј), 174.8 (C-3), 194.5 (C-1) ppm. EI-MS: m/z (rel. int.) ϭ 478
1-(4,6-Dibenzyloxy-2-hydroxyphenyl)-5-(3,4-dibenzyloxyphenyl)-3-
(3) [Mϩ·], 460 (6), 387 (7), 371 (3), 300 (3), 237 (26), 226 (8), 197
(2), 147 (3), 137 (8), 91 (100). C31H26O5 (478.5): calcd. C 77.81, H
5.48; found C 77.79, H 5.52.
hydroxy-2,4-pentadien-1-one (2i): Yield 64.9 % (2.24 g). M.p.
1
175Ϫ176 °C (recrystallised from ethanol). H NMR: δ ϭ 5.07 (s,
2 H, 6Ј-OCH2C6H5), 5.09 (s, 2 H, 4Ј-OCH2C6H5), 5.17 (s, 2 H, 3ЈЈ-
1-(4,6-Dibenzyloxy-2-hydroxyphenyl)-5-(4-benzyloxyphenyl)-3-
OCH2C6H5), 5.21 (s, 2 H, 4ЈЈ-OCH2C6H5), 5.99 (d, J ϭ 15.7 Hz, 1
hydroxy-2,4-pentadien-1-one (2f): Yield 79.1 % (2.31 g). M.p. H, 4-H), 6.13 (d, J ϭ 2.3 Hz, 1 H, 5Ј-H), 6.20 (d, J ϭ 2.3 Hz, 1 H,
178Ϫ180 °C (recrystallised from ethanol). 1H NMR: δ ϭ 5.08, 3Ј-H), 6.80 (s, 1 H, 2-H), 6.92 (d, J ϭ 8.3 Hz, 1 H, 5ЈЈ-H), 6.99
5.09, and 5.12 (3s, 6 H, 4Ј,6Ј,4ЈЈ-OCH2C6H5), 6.01 (d, J ϭ 16.5 Hz,
(dd, J ϭ 8.3, 1.8 Hz, 1 H, 6ЈЈ-H), 7.04 (d, J ϭ 1.8 Hz, 1 H, 2ЈЈ-H),
1 H, 4-H), 6.14 (d, J ϭ 2.4 Hz, 1 H, 5Ј-H), 6.20 (d, J ϭ 2.4 Hz, 1 7.35 (d, J ϭ 15.7 Hz, 1 H, 5-H), 7.26Ϫ7.53 (m, 20 H, 2,3,4,5,6-H
H, 3Ј-H), 6.79 (s, 1 H, 2-H), 6.98 (d, J ϭ 8.7 Hz, 2 H, 3ЈЈ,5ЈЈ-H), of 4Ј,6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 13.73 (s, 1 H, 2Ј-OH), 14.59 (d, J ϭ
7.26Ϫ7.54 (m, 17 H, 2ЈЈ,6ЈЈ-H and 2,3,4,5,6-H of 4Ј,6Ј,4ЈЈ- 0.8 Hz, 1 H, 3-OH) ppm. 13C NMR: δ ϭ 70.2 (6Ј-OCH2C6H5),
OCH2C6H5), 7.43 (d, J ϭ 16.5 Hz, 1 H, 5-H), 13.72 (s, 1 H, 2Ј- 71.0 (4ЈЈ-OCH2C6H5), 71.1 (4Ј-OCH2C6H5), 71.5 (3ЈЈ-OCH2C6H5),
OH), 14.57 (d, J ϭ 1.2 Hz, 1 H, 3-OH) ppm. 13C NMR: δ ϭ 70.1,
92.9 (C-5Ј), 95.2 (C-3Ј), 102.9 (C-2), 104.9 (C-1Ј), 113.7 (C-2ЈЈ),
70.2, and 71.2 (4Ј,6Ј,4ЈЈ-OCH2C6H5), 92.9 (C-5Ј), 95.2 (C-3Ј), 102.8 114.3 (C-5ЈЈ), 121.1 (C-4), 122.6 (C-6ЈЈ), 127.2, 127.4, 127.7, and
(C-2), 105.2 (C-1Ј), 115.2 (C-3ЈЈ,5ЈЈ), 120.9 (C-4), 127.5 (C-2,6 of 128.1 (C-1ЈЈ and C-2,6 of 4Ј,6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 127.9, 128.0,
4Ј,6Ј,4ЈЈ-OCH2C6H5), 127.7 (C-4 of 4Ј,6Ј,4ЈЈ-OCH2C6H5), 128.7 and 128.3 (C-4 of 4Ј,6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 128.6, 128.7, 128.7, and
(C-2ЈЈ,6ЈЈ), 129.3 (C-3,5 of 4Ј,6Ј,4ЈЈ-OCH2C6H5), 135.9 (C-1ЈЈ and 128.9 (C-3,5 of 4Ј,6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 135.9 and 136.9 (C-1 of
C-1 of 4Ј,6Ј,4ЈЈ-OCH2C6H5), 137.8 (C-5), 160.1 (C-4ЈЈ), 160.9 (C-
4Ј,6Ј,3ЈЈ,4ЈЈ-OCH2C6H5), 137.9 (C-5), 149.0 (C-3ЈЈ), 150.6 (C-4ЈЈ),
6Ј), 160.5 (C-4Ј), 167.2 (C-2Ј), 173.6 (C-3), 193.5 (C-1) ppm. EI- 160.9 (C-6Ј), 164.5 (C-4Ј), 167.2 (C-2Ј), 173.5 (C-3), 193.5 (C-1)
MS: m/z (rel. int.) ϭ 584 (1) [Mϩ·], 566 (2), 493 (1), 476 (3), 333 ppm. EI-MS: m/z (rel. int.) ϭ 690 (1) [Mϩ·], 672 (1), 582 (1), 491
4580
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 4575Ϫ4585

Synthesis of New Hydroxy-2-styrylchromones
(2), 358 (3), 306 (7), 267 (3), 243 (1), 215 (2), 181 (8), 91 (100). H), 7.63 (d, J ϭ 7.3 Hz, 2 H, 2,6-H of 5-OCH2C6H5) ppm. 13C
FULL PAPER
C45H38O7 (690.8): calcd. C 78.24, H 5.54; found C 78.16, H 5.54.
NMR: δ ϭ 70.8 (5-OCH2C6H5), 108.3 (C-6), 110.3 (C-8), 112.3 (C-
3), 115.2 (C-10), 119.9 (C-α), 126.6 (C-2,6 of 5-OCH2C6H5), 127.5
(C-2Ј,6Ј), 127.6 (C-4 of 5-OCH2C6H5), 128.5 (C-3,5 of 5-
OCH2C6H5), 128.9 (C-3Ј,5Ј), 129.6 (C-4Ј), 133.6 (C-7), 135.0 (C-
1Ј), 136.2 (C-β), 136.6 (C-1 of 5-OCH2C6H5), 158.0 (C-9), 158.5
(C-5), 159.5 (C-2), 178.1 (C-4) ppm. EI-MS: m/z (rel. int.) ϭ 354
(91) [Mϩ·], 353 (17), 277 (14), 264 (11), 248 (55), 247 (49), 231 (21),
218 (24), 91 (100). C24H18O3 (354.4): calcd. C 81.34, H 5.12; found
C 81.54, H 5.02.
Synthesis of Benzyloxy-2-styrylchromones 3a؊i. Method 1: A cata-
lytic amount of iodine (254 mg, 1 mmol) was added to a solution
of the appropriate 5-aryl-3-hydroxy-1-(2-hydroxyaryl)-2,4-pen-
tadien-1-one 2aϪi (5 mmol) in dimethyl sulfoxide (30 mL). The
solution was heated under nitrogen at 90 °C, until the complete
consumption of the starting material was observed. After that per-
iod, the solution was poured into ice and a saturated aqueous solu-
tion of sodium thiosulfate (100 mL). The solid was removed by
filtration, dissolved in dichloromethane (50 mL) and washed with
a saturated aqueous solution of sodium thiosulfate (2 ϫ 20 mL).
After evaporation of the solvent, the residue was purified by silica
gel column chromatography using a mixture of light petroleum:-
dichloromethane (1:1) as eluent. The solvent was evaporated to
dryness in each case, and the residue was crystallised from ethanol
to give benzyloxy-2-styrylchromones 3aϪi in the following yields:
3a (74.0 %, 1.31 g), 4b (9.0 %, 218 mg), 3c (37.0 %, 851 mg) and 4c
(4.0 %, 118 mg), 3d (9.0 %, 207 mg) and 4d (9.0 %, 313 mg), 3e
(4 %, 92 mg) and 4e (3.0 %, 105 mg), 3f (56.9 %, 1.61 g) and 4f
(5.0 %, 201 mg), 3g (62.9 %, 1.78 g), 3h (47.0 %, 1.33 g), 3i
(50.9 %, 1.71 g).
5,7-Dibenzyloxy-2-styrylchromone (3c): M.p. 161Ϫ163 °C (recrys-
1
tallised from ethanol). H NMR: δ ϭ 5.07 (s, 2 H, 7-OCH2C6H5),
5.14 (s, 2 H, 5-OCH2C6H5), 6.13 (s, 1 H, 3-H), 6.42 (d, J ϭ 2.2 Hz,
1 H, 6-H), 6.58 (d, J ϭ 2.2 Hz, 1 H, 8-H), 6.63 (d, J ϭ 16.0 Hz, 1
H, α-H), 7.24Ϫ7.44 (m, 9 H, 3Ј,4Ј,5Ј-H and 3,4,5-H of 5,7-
OCH2C6H5), 7.43 (d, J ϭ 16.0 Hz, 1 H, β-H), 7.50 (dd, J ϭ 7.2,
1.7 Hz, 4 H, 2Ј,6Ј-H and 2,6-H of 7-OCH2C6H5), 7.60 (d, J ϭ
7.4 Hz, 2 H, 2,6-H of 5-OCH2C6H5) ppm. 13C NMR: δ ϭ 70.3 (7-
OCH2C6H5), 70.4 (5-OCH2C6H5), 93.9 (C-8), 97.9 (C-6), 109.8 (C-
10), 112.2 (C-3), 119.8 (C-α), 126.4 (C-2,6 of 5-OCH2C6H5), 127.4
(C-4 of 5-OCH2C6H5), 127.4 and 127.5 (C-2Ј,6Ј and C-2,6 of 7-
OCH2C6H5), 128.3 (C-4 of 7-OCH2C6H5), 128.4, 128.6, and 128.8
(C-3Ј,5Ј and C-3,5 of 5,7-OCH2C6H5), 129.4 (C-4Ј), 135.0 (C-1Ј),
135.5 (C-β), 135.6 (C-1 of 7-OCH2C6H5), 136.2 (C-1 of 5-
OCH2C6H5), 158.9 (C-2), 159.3 (C-9), 159.5 (C-5), 162.8 (C-7),
177.2 (C-4) ppm. EI-MS: m/z (rel. int.) ϭ 460 (8) [Mϩ·], 383 (4),
370 (18), 354 (12), 341 (9), 263 (3), 235 (2), 155 (1), 131 (4), 128
(4), 123 (3), 115 (3), 91 (100). C31H24O4 (460.5): calcd. C 80.85, H
5.25; found C 80.48, H 5.19.
Method 2: p-Toluenesulfonic acid monohydrate (0.48 g, 2.5 mmol)
was added to a solution of the appropriate 5-aryl-3-hydroxy-1-(2-
hydroxyaryl)-2,4-pentadien-1-one 2aϪi (5 mmol) in dimethyl sul-
foxide (30 mL). The solution was heated under nitrogen at 90 °C,
until the complete consumption of the starting material was ob-
served. After that period, the solution was poured into ice and
water (100 mL), and the solid so-obtained was removed by fil-
tration. The solid was dissolved in dichloromethane (50 mL) and
the organic phase washed with water (2 ϫ 100 mL). After evapor-
ation of the solvent, the residue was purified by silica gel column
chromatography using a mixture of light petroleum:dichlorome-
thane (1:1) as eluent. The solvent was evaporated to dryness in
each case, and the residue was crystallised from ethanol to give
the benzyloxy-2-styrylchromones 3aϪi in the following yields: 3a
(19.0 %, 336 mg) and 4a (22.0 %, 532 mg), 3b (93.2 %, 1.65 g), 3c
(19.0 %, 437 mg) and 4c (48.8 %, 1.44 g), 3d (96.1 %, 2.21 g), 3e
(95.2 %, 2.19 g), 3f (82.0 %, 2.32 g), 3g (96.1 %, 2.72 g), 3h (84.1 %,
2.38 g), 3i (83.9 %, 2.82 g).
7,4Ј-Dibenzyloxy-2-styrylchromone (3d): M.p. 148Ϫ150 °C (recrys-
tallised from ethanol). 1H NMR: δ ϭ 5.10 (s, 2 H, 4Ј-OCH2C6H5),
5.18 (s, 2 H, 7-OCH2C6H5), 6.22 (s, 1 H, 3-H), 6.61 (d, J ϭ 16.0 Hz,
1 H, α-H), 6.99Ϫ7.03 (m, 4 H, 6,8,3Ј,5Ј-H), 7.25Ϫ7.45 (m, 10 H,
2,3,4,5,6-H of 7,4Ј-OCH2C6H5), 7.51 (d, J ϭ 8.7 Hz, 2 H, 2Ј,6Ј-H),
7.50 (d, J ϭ 16.0 Hz, 1 H, β-H), 8.10 (d, J ϭ 8.5 Hz, 1 H, 5-H)
ppm. 13C NMR: δ ϭ 70.1 (4Ј-OCH2C6H5), 70.5 (7-OCH2C6H5),
101.3 (C-8), 110.0 (C-3), 114.5 (C-3Ј,5Ј), 115.3 (C-6), 118.0 (C-α),
118.2 (C-10), 127.1 (C-1Ј), 127.5 (C-5), 127.5 and 128.1 (C-2,6 of
7,4Ј-OCH2C6H5), 128.2 and 128.4 (C-4 of 7,4Ј-OCH2C6H5), 128.7
and 128.8 (C-3,5, of 7,4Ј-OCH2C6H5), 129.2 (C-2Ј,6Ј), 135.8 (C-1
of 7-OCH2C6H5), 136.0 (C-β), 136.4 (C-1 of 4Ј-OCH2C6H5), 157.6
(C-9), 160.1 (C-4Ј), 161.8 (C-2), 163.1 (C-7), 177.9 (C-4) ppm. EI-
MS: m/z (rel. int.) ϭ 460 (28) [Mϩ·], 443 (1), 370 (7), 354 (4), 341
(2), 263 (2), 165 (2), 115 (2), 107 (1), 91 (100). C31H24O4 (460.5):
calcd. C 80.85, H 5.25; found C 80.69, H 5.16.
7-Benzyloxy-2-styrylchromone (3a): M.p. 161Ϫ163 °C (recrystal-
lised from ethanol). 1H NMR: δ ϭ 5.16 (s, 2 H, 7-OCH2C6H5),
6.24 (s, 1 H, 3-H), 6.72 (d, J ϭ 16.2 Hz, 1 H, α-H), 6.99 (br. s, 1
H, 8-H), 7.02 (dd, J ϭ 8.8, 2.3 Hz, 1 H, 6-H), 7.34Ϫ7.57 (m, 10
H, 2Ј,3Ј,4Ј,5Ј,6Ј-H and 2,3,4,5,6-H of 7-OCH2C6H5), 7.53 (d, J ϭ
16.2 Hz, 1 H, β-H), 8.08 (d, J ϭ 8.8 Hz, 1 H, 5-H) ppm. 13C NMR:
δ ϭ 70.4 (7-OCH2C6H5), 101.2 (C-8), 110.6 (C-3), 114.5 (C-6),
118.1 (C-10), 120.2 (C-α), 127.0 (C-5), 127.4 (C-2,6 of 7-
OCH2C6H5), 127.5 (C-2Ј,6Ј), 128.3 (C-4 of 7-OCH2C6H5), 128.7
(C-3,5 of 7-OCH2C6H5), 128.9 (C-3Ј,5Ј), 129.7 (C-4Ј), 134.9 (C-1Ј),
135.7 (C-1 of 7-OCH2C6H5), 136.2 (C-β), 157.5 (C-9), 161.2 (C-2),
163.1 (C-7), 177.7 (C-4) ppm. EI-MS: m/z (rel. int.) ϭ 354 (69)
[Mϩ·], 263 (8), 235 (13), 178 (8), 128 (10), 103 (6), 91 (100).
C24H18O3 (354.4): calcd. C 81.34, H 5.12; found C 81.23, H 5.08.
5,4Ј-Dibenzyloxy-2-styrylchromone (3e): M.p. 154Ϫ156 °C (recrys-
1
tallised from ethanol). H NMR: δ ϭ 5.09 (s, 2 H, 5-OCH2C6H5),
5.26 (s, 2 H, 4Ј-OCH2C6H5), 6.19 (s, 1 H, 3-H), 6.58 (d, J ϭ
15.8 Hz, 1 H, α-H), 6.81 (d, J ϭ 8.5 Hz, 1 H, 6-H), 6.99 (d, J ϭ
8.7 Hz, 2 H, 3Ј,5Ј-H), 7.08 (d, J ϭ 8.5 Hz, 1 H, 8-H), 7.27Ϫ7.42
(m, 10 H, 2Ј,6Ј-H, 3,4,5-H of 5-OCH2C6H5 and 2,3,4,5,6-H of 4Ј-
OCH2C6H5), 7.47 (d, J ϭ 15.8 Hz, 1 H, β-H), 7.48 (t, J ϭ 8.5 Hz,
1 H, 7-H), 7.63 (d, J ϭ 7.4 Hz, 2 H, 2,6-H of 5-OCH2C6H5) ppm.
13C NMR: δ ϭ 70.0 (5-OCH2C6H5), 70.7 (4Ј-OCH2C6H5), 108.2
(C-6), 110.2 (C-8), 111.6 (C-3), 115.2 (C-10,3Ј,5Ј), 117.6 (C-α),
5-Benzyloxy-2-styrylchromone (3b): M.p. 179Ϫ181 °C (recrystal-
lised from ethanol). 1H NMR: δ ϭ 5.28 (s, 2 H, 5-OCH2C6H5), 126.5 (C-2,6 of 5-OCH2C6H5), 127.4 (C-2,6 of 4Ј-OCH2C6H5),
6.24 (s, 1 H, 3-H), 6.74 (d, J ϭ 16.0 Hz, 1 H, α-H), 6.83 (d, J ϭ 127.5 and 128.1 (C-4 of 5,4Ј-OCH2C6H5), 128.0 (C-1Ј), 128.5 and
8.3 Hz, 1 H, 6-H), 7.11 (d, J ϭ 8.3 Hz, 1 H, 8-H), 7.29 (t, J ϭ 128.6 (C-3,5, of 5,4Ј-OCH2C6H5), 129.1 (C-2Ј,6Ј), 133.4 (C-7),
7.3 Hz, 1 H, 4-H of 5-OCH2C6H5), 7.37Ϫ7.44 (m, 5 H, 3Ј,4Ј,5Ј-H 135.8 (C-β), 136.4 and 136.6 (C-1 of 5, 4Ј-OCH2C6H5), 158.0 (C-
and 3,5-H of 5-OCH2C6H5), 7.51 (t, J ϭ 8.3 Hz, 1 H, 7-H), 7.54
(d, J ϭ 16.0 Hz, 1 H, β-H), 7.57 (dd, J ϭ 7.7, 1.4 Hz, 2 H, 2Ј,6Ј-
9), 158.4 (C-4Ј), 159.9 (C-2), 160.0 (C-5), 178.1 (C-4) ppm. EI-MS:
m/z (rel. int.) ϭ 460 (33) [Mϩ·], 370 (8), 354 (5), 263 (2), 115 (1),
Eur. J. Org. Chem. 2003, 4575Ϫ4585
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4581

C. M. M. Santos, A. M. S. Silva, J. A. S. Cavaleiro
FULL PAPER
91 (100). C31H24O4 (460.5): calcd. C 80.85, H 5.25; found C 80.53,
H 4.89.
OCH2C6H5), 5.21 and 5.22 (2s, 6 H, 5,3Ј,4Ј-OCH2C6H5), 6.13 (s, 1
H, 3-H), 6.48 (d, J ϭ 2.3 Hz, 1 H, 6-H), 6.50 (d, J ϭ 15.9 Hz, 1
H, α-H), 6.62 (d, J ϭ 2.3 Hz, 1 H, 8-H), 6.94 (d, J ϭ 8.4 Hz, 1 H,
5Ј-H), 7.10 (dd, J ϭ 8.4, 1.9 Hz, 1 H, 6Ј-H), 7.16 (d, J ϭ 1.9 Hz,
1 H, 2Ј-H), 7.36 (d, J ϭ 15.9 Hz, 1 H, β-H), 7.27Ϫ7.50 (m, 13 H,
3,4,5-H of 5-OCH2C6H5 and 7,4Ј-OCH2C6H5), 7.62 (d, J ϭ 7.2 Hz,
2 H, 2,6-H of 5-OCH2C6H5) ppm. 13C NMR: δ ϭ 70.5, 70.7, 71.0,
and 71.4 (5,7,3Ј,4Ј-OCH2C6H5), 94.1 (C-8), 98.1 (C-6), 110.0 (C-
10), 111.8 (C-3), 113.3 (C-2Ј), 114.4 (C-5Ј), 118.1 (C-α), 122.1 (C-
6Ј), 126.5 (C-2,6 of 5-OCH2C6H5), 127.2, 127.3, and 127.6 (C-2,6
of 7,3Ј,4Ј-OCH2C6H5), 128.0 and 128.4 (C-4 of 5,7,3Ј,4Ј-
OCH2C6H5), 128.6 (C-1Ј), 128.6, 128.8 (C-3,5 of 5,7,3Ј,4Ј-
OCH2C6H5), 135.4 (C-β), 135.7 (C-1 of 7-OCH2C6H5), 136.4,
136.8, and 136.9 (C-1 of 5,3Ј,4Ј-OCH2C6H5), 149.1 (C-3Ј), 150.5
(C-4Ј), 159.4 (C-2), 159.5 (C-9), 159.7 (C-5), 162.9 (C-7), 177.4 (C-
4) ppm. EI-MS: m/z (rel. int.) ϭ 672 (3) [Mϩ·], 582 (5), 491 (5), 292
(12), 277 (11), 263 (10), 247 (4), 181 (4), 115 (7), 106 (3), 91 (100).
C45H36O6 (672.8): calcd. C 80.34, H 5.39; found C 80.30, H. 5.66.
5,7,4Ј-Tribenzyloxy-2-styrylchromone (3f): M.p. 170Ϫ172 °C
(recrystallised from ethanol). 1H NMR: δ ϭ 5.12 (s, 2 H, 4Ј-
OCH2C6H5), 5.13 (s, 2 H, 7-OCH2C6H5), 5.22 (s, 2 H, 5-
OCH2C6H5), 6.15 (s, 1 H, 3-H), 6.49 (d, J ϭ 2.2 Hz, 1 H, 6-H),
6.59 (d, J ϭ 15.8 Hz, 1 H, α-H), 6.64 (d, J ϭ 2.2 Hz, 1 H, 8-H),
7.01 (d, J ϭ 8.7 Hz, 2 H, 3Ј,5Ј-H), 7.30Ϫ7.48 (m, 15 H, 5,7,4Ј-
OCH2C6H5), 7.43 (d, J ϭ 15.8 Hz, 1 H, β-H), 7.51 (d, J ϭ 8.7 Hz,
2 H, 2Ј,6Ј-H), 7.62 (d, J ϭ 7.4 Hz, 2 H, 2,6-H of 5-OCH2C6H5)
ppm. 13C NMR: δ ϭ 70.1 (4Ј-OCH2C6H5), 70.4 (7-OCH2C6H5),
70.6 (5-OCH2C6H5), 94.1 (C-8), 98.1 (C-6), 110.0 (C-10), 111.7 (C-
3), 115.2 (C-3Ј,5Ј), 117.7 (C-α), 126.5 (C-2,6 of 5-OCH2C6H5),
127.5 and 127.6 (C-2,6 of 7,4Ј-OCH2C6H5), 127.6 (C-4 of 5-
OCH2C6H5), 128.1 and 128.4 (C-4 of 7,4Ј-OCH2C6H5), 128.2 (C-
1Ј), 128.6, 128.7, and 128.8 (C-3,5 of 5,7,4ЈЈ-OCH2C6H5), 129.0 (C-
2Ј,6Ј), 135.2 (C-β), 135.7, 136.4, and 136.5 (C-1 of 5,7,4ЈЈ-
OCH2C6H5), 159.5 (C-2,9), 159.6 (C-5), 160.0 (C-4Ј), 162.8 (C-7),
177.4 (C-4) ppm. EI-MS: m/z (rel. int.) ϭ 566 (3) [Mϩ·], 476 (7),
386 (1), 147 (5), 133 (3), 121 (4), 107 (4), 105 (3), 91 (100).
C38H30O5 (566.7): calcd. C 80.55, H 5.34; found C 80.49, H 5.10.
7-Benzyloxy-3-cinnamoyl-2-styrylchromone (4a): M.p. 82Ϫ83 °C
(recrystallised from ethanol). 1H NMR: δ ϭ 5.23 (s, 2 H, 7-
OCH2C6H5), 7.07 (br. s, 1 H, 8-H), 7.09 (dd, J ϭ 7.6, 2.1 Hz, 1 H,
6-H), 7.17 (d, J ϭ 15.9 Hz, 1 H, α-H), 7.26 (d, J ϭ 15.9 Hz, 1 H,
αЈ-H), 7.37Ϫ7.51 (m, 11 H, 3Ј,4Ј,5Ј-H, 3ЈЈ,4ЈЈ,5ЈЈ-H and 2,3,4,5,6-
H of 7-OCH2C6H5), 7.57Ϫ7.64 (m, 4 H, 2Ј,6Ј-H and 2ЈЈ,6ЈЈ-H),
7.67 (d, J ϭ 15.9 Hz, 1 H, βЈ-H), 7.74 (d, J ϭ 15.9 Hz, 1 H, β-
H), 8.15 (d, J ϭ 7.6 Hz, 1 H, 5-H) ppm. 13C NMR: δ ϭ 70.6 (7-
OCH2C6H5), 101.2 (C-8), 115.1 (C-6), 117.8 (C-10), 118.0 (C-α),
122.2 (C-3), 127.5 (C-αЈ), 128.1 (C-5), 128.4, 128.7, 128.8, and
128.9 (C-3Ј,4Ј,5Ј,3ЈЈ,4ЈЈ,5ЈЈ and C-2,3,4,5,6 of 7-OCH2C6H5), 130.2
(C-2Ј,6Ј), 130.6 (C-2ЈЈ,6ЈЈ), 134.6 (C-1ЈЈ), 134.9 (C-1Ј), 135.6 (C-1
of 7-OCH2C6H5), 139.1 (C-β), 144.2 (C-βЈ), 156.9 (C-9), 161.1 (C-
2), 163.7 (C-7), 175.8 (C-4), 192.1 (CϭO) ppm. EI-MS: m/z (rel.
int.) ϭ 484 (55) [Mϩ·], 483 (8), 407 (17), 393 (5), 365 (6), 131 (9),
122 (7), 103 (15), 91 (100), 77 (8), 65 (8). C33H24O4 (484.5): calcd.
C 81.80, H 4.99; found C 81.84, H. 4.97.
7,3Ј,4Ј-Tribenzyloxy-2-styrylchromone (3g): M.p. 161Ϫ163 °C
(recrystallised from ethanol). 1H NMR: δ ϭ 5.19 (s, 2 H, 7-
OCH2C6H5), 5.22 (s, 2 H, 3Ј-OCH2C6H5), 5.23 (s, 2 H, 4Ј-
OCH2C6H5), 6.22 (s, 1 H, 3-H), 6.54 (d, J ϭ 15.9 Hz, 1 H, α-H),
6.95 (d, J ϭ 8.3 Hz, 1 H, 5Ј-H), 7.00Ϫ7.02 (m, 1 H, 6-H), 7.05 (d,
J ϭ 2.3 Hz, 1 H, 8-H), 7.10 (dd, J ϭ 8.3, 1.9 Hz, 1 H, 6Ј-H), 7.17
(d, J ϭ 1.9 Hz, 1 H, 2Ј-H), 7.32Ϫ7.50 (m, 15 H, 2,3,4,5,6-H of
7,3Ј,4Ј-OCH2C6H5), 7.43 (d, J ϭ 15.9 Hz, 1 H, β-H), 8.11 (d, J ϭ
8.7 Hz, 1 H, 5-H) ppm. 13C NMR: δ ϭ 70.5 (7-OCH2C6H5), 71.0
(3Ј-OCH2C6H5), 71.4 (4Ј-OCH2C6H5), 101.3 (C-8), 110.1 (C-3),
113.3 (C-2Ј), 114.4 (C-5Ј), 114.5 (C-6), 118.2 (C-10), 118.3 (C-α),
122.3 (C-6Ј), 127.2, 127.3, and 127.5 (C-2,6 of 7,3Ј,4Ј-OCH2C6H5),
127.5 (C-5), 128.0 and 128.4 (C-1Ј and C-4 of 7,3Ј,4Ј-OCH2C6H5),
128.6 and 128.8 (C-3,5 of 7,3Ј,4Ј-OCH2C6H5), 135.8, 136.7, and
136.9 (C-1 of 7,3Ј,4Ј-OCH2C6H5), 136.1 (C-β), 149.1 (C-3Ј), 150.6
(C-4Ј), 157.6 (C-9), 161.7 (C-2), 163.2 (C-7), 177.8 (C-4) ppm. EI-
MS: m/z (rel. int.) ϭ 566 (9) [Mϩ·], 475 (11), 131 (3), 118 (2), 106
(15), 91 (100). C38H30O5 (566.6): calcd. C 80.55, H 5.34; found C
80.24, H 5.50.
5-Benzyloxy-3-cinnamoyl-2-styrylchromone (4b): M.p. 184Ϫ186 °C
(recrystallised from ethanol). 1H NMR: δ ϭ 5.31 (s, 2 H, 5-
OCH2C6H5), 6.88 (d, J ϭ 8.2 Hz, 1 H, 6-H), 7.15 (d, J ϭ 8.2 Hz,
1 H, 8-H), 7.06 (d, J ϭ 15.9 Hz, 1 H, α-H), 7.25 (d, J ϭ 16.0 Hz,
1 H, αЈ-H), 7.31Ϫ7.40 (m, 9 H, 3Ј,4Ј,5Ј,3ЈЈ,4ЈЈ,5ЈЈ-H and 3,4,5-H
of 5-OCH2C6H5), 7.54Ϫ7.62 (m, 7 H, 7,2Ј,6Ј,2ЈЈ,6ЈЈ-H and 2,6-H
of 5-OCH2C6H5), 7.69 (d, J ϭ 16.0 Hz, 1 H, βЈ-H), 7.71 (d, J ϭ
15.9 Hz, 1 H, β-H) ppm. 13C NMR: δ ϭ 71.0 (5-OCH2C6H5), 108.7
(C-6), 110.2 (C-8), 114.9 (C-10), 117.8 (C-α), 123.7 (C-3), 126.6 (C-
2,6 of 5-OCH2C6H5), 127.6 (C-αЈ), 127.7 (C-4 of 5-OCH2C6H5),
128.1 (C-2Ј,6Ј), 128.6 (C-2ЈЈ,6ЈЈ), 128.8 (C-3ЈЈ,5ЈЈ and C-3,5 of 5-
OCH2C6H5), 128.9 (C-3Ј,5Ј), 130.1 (C-4Ј), 130.6 (C-4ЈЈ), 134.2 (C-
1ЈЈ), 134.6 (C-1Ј), 135.0 (C-7), 136.3 (C-1 of 5-OCH2C6H5), 139.0
(C-β), 144.2 (C-βЈ), 157.3 (C-9), 158.8 (C-5), 159.1 (C-2), 176.2 (C-
4), 192.4 (CϭO) ppm. EI-MS: m/z (rel. int.) ϭ 484 (41) [Mϩ·], 393
(100), 365 (11), 291 (13), 127 (17), 103 (16), 91 (100), 77 (16), 65
(15). C33H24O4 (484.5): calcd. C 81.80, H 4.99; found C 81.71, H.
5.03.
5,3Ј,4Ј-Tribenzyloxy-2-styrylchromone (3h): M.p. 172Ϫ173 °C
(recrystallised from ethanol). 1H NMR: δ ϭ 5.21 and 5.22 (2s, 4
H, 3Ј,4Ј-OCH2C6H5), 5.28 (s, 2 H, 5-OCH2C6H5), 6.19 (s, 1 H, 3-
H), 6.52 (d, J ϭ 15.9 Hz, 1 H, α-H), 6.83 (d, J ϭ 8.0 Hz, 1 H, 6-
H), 6.94 (d, J ϭ 8.2 Hz, 1 H, 5Ј-H), 7.09 (d, J ϭ 8.0 Hz, 1 H, 8-
H), 7.11 (dd, J ϭ 8.2, 1.8 Hz, 1 H, 6Ј-H), 7.17 (d, J ϭ 1.8 Hz, 1
H, 2Ј-H), 7.30Ϫ7.53 (m, 14 H, 7-H, 3,4,5-H of 5-OCH2C6H5 and
2,3,4,5,6-H of 3Ј,4Ј-OCH2C6H5), 7.42 (d, J ϭ 15.9 Hz, 1 H, β-H),
7.63 (d, J ϭ 7.4 Hz, 2 H, 2,6-H of 5-OCH2C6H5) ppm. 13C NMR:
δ ϭ 70.8 and 71.4 (3Ј,4Ј-OCH2C6H5), 71.0 (5-OCH2C6H5), 108.3
(C-6), 110.3 (C-8), 111.8 (C-3), 113.3 (C-2Ј), 114.4 (C-5Ј), 115.2 (C-
10), 118.0 (C-α), 122.3 (C-6Ј), 126.6 (C-2,6 of 5-OCH2C6H5), 127.2
and 127.3 (C-2,6 of 3Ј,4Ј-OCH2C6H5), 127.6 and 128.0 (C-4 of
5,3Ј,4Ј-OCH2C6H5), 128.4 and 128.7 (C-3,5 of 5,3Ј,4Ј-OCH2C6H5),
128.6 (C-1Ј), 133.5 (C-7), 136.0 (C-β), 136.6, 136.8, and 136.9 (C-
1 of 5,3Ј,4Ј-OCH2C6H5), 149.1 (C-3Ј), 150.6 (C-4Ј), 158.1 (C-9),
158.5 (C-5), 159.8 (C-2), 178.2 (C-4) ppm. EI-MS: m/z (rel. int.) ϭ
566 (9) [Mϩ·], 476 (9), 385 (5), 181 (3), 106 (3), 91 (100). C38H30O5
(566.6): calcd. C 80.55, H 5.34; found C 80.47, H 5.67.
5,7-Dibenzyloxy-3-cinnamoyl-2-styrylchromone (4c): M.p. 194Ϫ196
°C (recrystallised from ethanol). 1H NMR: δ ϭ 5.16 (s, 2 H, 7-
OCH2C6H5), 5.24 (s, 2 H, 5-OCH2C6H5), 6.53 (d, J ϭ 2.0 Hz, 1
H, 6-H), 6.69 (d, J ϭ 2.0 Hz, 1 H, 8-H), 7.04 (d, J ϭ 15.9 Hz, 1
H, α-H), 7.25 (d, J ϭ 15.9 Hz, 1 H, αЈ-H), 7.28Ϫ7.46 (m, 14 H,
3Ј,4Ј,5Ј,3ЈЈ,4ЈЈ,5ЈЈ-H, 3,4,5-H of 5-OCH2C6H5 and 2,3,4,5,6-H of
7-OCH2C6H5), 7.55Ϫ7.61 (m, 6 H, 2Ј,6Ј,2ЈЈ,6ЈЈ-H and 2,6-H of 5-
OCH2C6H5), 7.66 (d, J ϭ 15.9 Hz, 1 H, βЈ-H), 7.68 (d, J ϭ
15.9 Hz, 1 H, β-H) ppm. 13C NMR: δ ϭ 70.6 (7-OCH2C6H5), 70.8
5,7,3Ј,4Ј-Tetrabenzyloxy-2-styrylchromone (3i): M.p. 92Ϫ94 °C
(recrystallised from ethanol). 1H NMR: δ ϭ 5.12 (s, 2 H, 7-
4582
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 4575Ϫ4585

Synthesis of New Hydroxy-2-styrylchromones
FULL PAPER
(5-OCH2C6H5), 94.0 (C-8), 98.5 (C-6), 109.6 (C-10), 117.8 (C-α), OCH2C6H5), 7.58 (d, J ϭ 16.1 Hz, 1 H, βЈ-H), 7.63 (d, J ϭ
123.6 (C-3), 126.6 (C-2,6 of 5-OCH2C6H5), 127.2 (C-2,6 of 7-
OCH2C6H5), 128.0 (C-αЈ), 128.5, 128.6, 128.7, 128.8, and 128.9 (C-
15.9 Hz, 1 H, β-H) ppm. 13C NMR: δ ϭ 70.1 (4Ј,4ЈЈ-OCH2C6H5),
70.6 (7-OCH2C6H5), 70.8 (5-OCH2C6H5), 94.0 (C-8), 98.4 (C-6),
3Ј,4Ј,5Ј and 3ЈЈ,4ЈЈ,5ЈЈ and C-3,4,5 of 5,7-OCH2C6H5), 130.0 (C- 109.6 (C-10), 115.1 (C-3ЈЈ,5ЈЈ), 115.2 (C-3Ј,5Ј), 115.6 (C-α), 123.2
2Ј,6Ј), 130.5 (C-2ЈЈ,6ЈЈ), 134.7 (C-1ЈЈ), 135.0 (C-1Ј), 135.5 (C-1 of (C-3), 125.9 (C-αЈ), 126.6, 127.5, 127.7, 127.9, 128.1, 128.5, 128.6,
7-OCH2C6H5), 136.1 (C-1 of 5-OCH2C6H5), 138.3 (C-β), 144.0 (C-
βЈ), 158.6 (C-2), 158.8 (C-9), 160.0 (C-5), 163.4 (C-7), 175.4 (C-4), 129.6 (C-2Ј,6Ј), 130.6 (C-2ЈЈ,6ЈЈ), 135.6 (C-1 of 7-OCH2C6H5),
192.6 (CϭO) ppm. EI-MS: m/z (rel. int.) ϭ 590 (9) [Mϩ·], 500 (18),
136.2 (C-1 of 5-OCH2C6H5), 136.4 (C-1 of 4Ј,4ЈЈ-OCH2C6H5),
499 (14), 132 (9), 131 (9), 117 (5), 103 (7), 91 (100), 77 (6), 65 (10). 137.8 (C-β), 144.1 (C-βЈ), 158.8 (C-2,9), 160.0 (C-5), 160.3 (C-4Ј),
and 128.8 (C-1Ј, C-1ЈЈ and C-2,3,4,5,6 of 5,7,4Ј,4ЈЈ-OCH2C6H5),
C40H30O5 (590.7): calcd. C 81.34, H 5.12; found C 81.01, H. 5.09.
160.8 (C-4ЈЈ), 163.3 (C-7), 175.4 (C-4), 192.7 (CϭO) ppm. MS-
FABϩ: m/z (rel. int.) ϭ 803 (10) [M ϩ H]ϩ, 802 (5), 711 (5), 503
(6), 237 (10), 154 (8), 136 (12), 107 (6), 91 (100), 77 (8), 73 (19).
FAB-HRMS (C54H43O7, [M ϩ H]ϩ): calcd. 803.2931, found
803.2941.
7,4Ј-Dibenzyloxy-3-(4-benzyloxycinnamoyl)-2-styrylchromone (4d):
Yellowish oil. 1H NMR: δ ϭ 5.09 and 5.09 (2s, 4 H, 4Ј,4ЈЈ-
OCH2C6H5), 5.30 (s, 2 H, 5-OCH2C6H5), 6.85 (s, 1 H, 8-H), 6.90
(d, J ϭ 15.8 Hz, 1 H, α-H), 6.96 (d, J ϭ 8.8 Hz, 2 H, 3ЈЈ,5ЈЈ-H),
6.97 (d, J ϭ 8.7 Hz, 2 H, 3Ј,5Ј-H), 7.11 (d, J ϭ 16.0 Hz, 1 H, αЈ-
H), 7.13 (d, J ϭ 8.0 Hz, 1 H, 6-H), 7.28Ϫ7.44 (m, 13 H, 3,4,5-H
of 7-OCH2C6H5 and 2,3,4,5,6-H of 4Ј,4ЈЈ-OCH2C6H5), 7.51 (d, J ϭ
8.7 Hz, 2 H, 2Ј,6Ј-H), 7.53 (t, J ϭ 8.0 Hz, 1 H, 5-H), 7.55 (d, J ϭ
8.8 Hz, 2 H, 2ЈЈ,6ЈЈ-H), 7.59 (d, J ϭ 7.2 Hz, 2 H, 2,6-H of 7-
OCH2C6H5), 7.64 (d, J ϭ 16.0 Hz, 1 H, βЈ-H), 7.64 (d, J ϭ
15.8 Hz, 1 H, β-H) ppm. 13C NMR: δ ϭ 70.0 and 70.1 (4Ј,4ЈЈ-
OCH2C6H5), 70.6 (7-OCH2C6H5), 101.2 (C-8), 114.9 (C-6), 115.2
(C-3ЈЈ,5ЈЈ), 115.3 (C-3Ј,5Ј), 115.9 (C-α), 117.9 (C-10), 121.7 (C-3),
125.7 (C-αЈ), 127.5 (C-5), 127.6, 128.1, 128.1, 128.1, 128.4, 128.6,
and 128.8 (C-1Ј,1ЈЈ and C-2,3,4,5,6 of 4Ј,4ЈЈ-OCH2C6H5), 129.8 (C-
2Ј,6Ј), 130.5 (C-2ЈЈ,6ЈЈ), 135.6 (C-1 of 7-OCH2C6H5), 136.4 (C-1 of
4Ј,4ЈЈ-OCH2C6H5), 138.6 (C-β), 144.1 (C-βЈ), 156.9 (C-9), 160.5 (C-
4Ј), 160.9 (C-4ЈЈ), 161.3 (C-2), 163.5 (C-7), 175.8 (C-4), 192.2 (Cϭ
O) ppm. MS-FAB(ϩ): m/z (rel. int.) ϭ 697 (30) [M ϩ H]ϩ, 696
(12), 605 (4), 461 (5), 397 (8), 307 (28), 289 (3), 237 (8), 154 (88),
137 (57), 136 (56), 120 (10), 107 (18), 91 (100), 77 (16). FAB-HRMS
(C47H37O6, [M ϩ H]ϩ): calcd. 697.2512, found 697.2505.
Synthesis of Hydroxy-2-styrylchromones 5a؊i: The appropriate
benzyloxy-2-styrylchromone 3aϪi (2.5 mmol) was added to a solu-
tion of hydrogen bromide in acetic acid (33 %, 50 mL). The mixture
was refluxed for 1Ϫ2 hours. The solution was carefully poured into
ice and water, and the solid so-obtained was removed by filtration.
The solid was dissolved in ethyl acetate (20 mL) and washed with
water several times. After evaporation of the solvent, the residue
was purified by silica gel column chromatography using a mixture
of chloroform:acetone (8:2) as eluent. The solvent was evaporated
to dryness in each case, and the residue was precipitated from etha-
nol with water to give the expected products 5aϪi.
7-Hydroxy-2-styrylchromone (5a): Yield 58.0 % (383 mg). M.p.
195Ϫ197 °C (recrystallised from a mixture of ethanol and water).
1H NMR ([D6]DMSO): δ ϭ 6.34 (s, 1 H, 3-H), 6.90 (dd, J ϭ 8.7,
2.2 Hz, 1 H, 6-H), 6.95 (d, J ϭ 2.2 Hz, 1 H, 8-H), 7.18 (d, J ϭ
16.2 Hz, 1 H, α-H), 7.40Ϫ7.48 (m, 3 H, 3Ј,4Ј,5Ј-H), 7.65 (d, J ϭ
16.2 Hz, 1 H, β-H), 7.72 (d, J ϭ 6.9 Hz, 2 H, 2Ј,6Ј-H), 7.85 (d,
J ϭ 8.7 Hz, 1 H, 5-H), 10.84 (br. s, 1 H, 7-OH) ppm. 13C NMR
([D6]DMSO): δ ϭ 102.4 (C-8), 110.0 (C-3), 114.8 (C-6), 116.4 (C-
10), 120.7 (C-α), 126.6 (C-5), 127.7 (C-2Ј,6Ј), 129.0 (C-3Ј,5Ј), 129.7
(C-4Ј), 135.1 (C-1Ј), 135.7 (C-β), 157.3 (C-9), 161.0 (C-2), 162.8 (C-
7), 176.4 (C-4) ppm. EI-MS: m/z (rel. int.) ϭ 264 (83) [Mϩ·], 263
(100), 247 (43), 235 (13), 207 (6), 178 (6), 155 (12), 137 (32), 128
(47), 118 (9), 108 (12), 102 (12), 91 (6), 77 (9), 63 (7), 51 (11).
C17H12O3 (264.3): calcd. C 77.26, H 4.58; found C 76.83, H 5.02.
5,4Ј-Dibenzyloxy-3-(4-benzyloxycinnamoyl)-2-styrylchromone (4e):
M.p. 192Ϫ194 °C (recrystallised from ethanol). 1H NMR: δ ϭ 5.09
(s, 4 H, 4Ј,4ЈЈ-OCH2C6H5), 5.29 (s, 2 H, 5-OCH2C6H5), 6.86 (d,
J ϭ 8.0 Hz, 1 H, 6-H), 6.90 (d, J ϭ 15.9 Hz, 1 H, α-H), 6.94 (d,
J ϭ 8.7 Hz, 2 H, 3ЈЈ,5ЈЈ-H), 6.97 (d, J ϭ 8.7 Hz, 2 H, 3Ј,5Ј-H), 7.11
(d, J ϭ 15.9 Hz, 1 H, αЈ-H), 7.12 (d, J ϭ 8.0 Hz, 1 H, 8-H),
7.28Ϫ7.44 (m, 13 H, 3,4,5-H of 5-OCH2C6H5 and 2,3,4,5,6-H of
4Ј,4ЈЈ-OCH2C6H5), 7.50 (d, J ϭ 8.8 Hz, 2 H, 2Ј,6Ј-H), 7.54 (t, J ϭ
8.0 Hz, 1 H, 7-H), 7.55 (d, J ϭ 8.8 Hz, 2 H, 2ЈЈ,6ЈЈ-H), 7.58 (d,
J ϭ 8.2 Hz, 2 H, 2,6-H of 5-OCH2C6H5), 7.64 (d, J ϭ 15.9 Hz, 2
H, β,βЈ-H) ppm. 13C NMR: δ ϭ 70.1 (4Ј,4ЈЈ-OCH2C6H5), 70.9 (5-
OCH2C6H5), 108.6 (C-6), 110.1 (C-8), 114.9 (C-10), 115.1 (C-
3ЈЈ,5ЈЈ), 115.2 (C-3Ј,5Ј), 115.5 (C-α), 123.2 (C-3), 125.7 (C-αЈ),
126.7 (C-2,6 of 5-OCH2C6H5), 127.5 (C-2,6 of 4Ј,4ЈЈ-OCH2C6H5),
127.6, 128.0, 128.1, and 128.6 (C-1Ј,1ЈЈ and C-3,4,5 of 5,4Ј,4ЈЈ-
OCH2C6H5), 129.7 (C-2Ј,6Ј), 130.6 (C-2ЈЈ,6ЈЈ), 134.0 (C-7), 136.4
(C-1 of 5,4Ј,4ЈЈ-OCH2C6H5), 138.3 (C-β), 144.2 (C-βЈ), 157.3 (C-
9), 158.8 (C-5), 159.2 (C-2), 160.4 (C-4Ј), 160.8 (C-4ЈЈ), 176.1 (C-
4), 192.5 (CϭO) ppm. MS-FABϩ: m/z (rel. int.) ϭ 697 (25) [M ϩ
H]ϩ, 696 (10), 605 (3), 460 (6), 397 (6), 307 (38), 289 (16), 212 (8),
180 (7), 154 (100), 137 (63), 136 (62), 120 (11), 107 (19), 91 (59),
77 (16), 65 (87), 51 (7). FAB-HRMS (C47H37O6, [M ϩ H]ϩ): calcd.
697.2512, found 697.2519.
5-Hydroxy-2-styrylchromone (5b): Yield 51.1 % (337 mg). M.p.
152Ϫ154 °C (recrystallised from a mixture of ethanol and water).
1H NMR: δ ϭ 6.24 (s, 1 H, 3-H), 6.75 (d, J ϭ 16.0 Hz, 1 H, α-H),
6.79 (dd, J ϭ 8.3, 0.8 Hz, 1 H, 6-H), 6.96 (dd, J ϭ 8.3, 0.8 Hz, 1
H, 8-H), 7.42 (m, 3 H, 3Ј,4Ј,5Ј-H), 7.52 (t, J ϭ 8.3 Hz, 1 H, 7-H),
7.58 (m, 2 H, 2Ј,6Ј-H), 7.61 (d, J ϭ 16.0 Hz, 1 H, β-H), 12.60 (s, 1
H, 5-OH) ppm. 13C NMR: δ ϭ 106.8 (C-8), 109.0 (C-3), 110.9 (C-
10), 111.3 (C-6), 119.5 (C-α), 127.8 (C-2Ј,6Ј), 129.0 (C-3Ј,5Ј), 130.2
(C-4Ј), 134.7 (C-1Ј), 135.3 (C-7), 138.0 (C-β), 156.2 (C-9), 160.8 (C-
5), 162.8 (C-2), 183.6 (C-4) ppm. EI-MS: m/z (rel. int.) ϭ 264 (100)
[Mϩ·], 263 (84), 246 (32), 235 (6), 218 (8), 189 (7), 155 (7), 136 (22),
128 (35), 127 (11), 108 (24), 102 (8), 91 (6), 77 (8), 51 (7). C17H12O3
(264.3): calcd. C 77.26, H 4.58; found C 77.13, H 4.57.
5,7-Dihydroxy-2-styrylchromone (5c): Yield 48.0 % (336 mg). M.p.
246Ϫ248 °C (recrystallised from a mixture of ethanol and water).
1H NMR ([D6]DMSO): δ ϭ 6.19 (d, J ϭ 2.1 Hz, 1 H, 6-H), 6.39
5,7,4Ј-Tribenzyloxy-3-(4-benzyloxycinnamoyl)-2-styrylchromone
1
(4f): Yellowish oil. H NMR: δ ϭ 5.08 (s, 4 H, 4Ј,4ЈЈ-OCH2C6H5), (s, 1 H, 3-H), 6.47 (d, J ϭ 2.1 Hz, 1 H, 8-H), 7.18 (d, J ϭ 16.2 Hz,
5.14 (s, 2 H, 7-OCH2C6H5), 5.21 (s, 2 H, 5-OCH2C6H5), 6.49 (d, 1 H, α-H), 7.41Ϫ7.49 (m, 3 H, 3Ј,4Ј,5Ј-H), 7.67 (d, J ϭ 16.2 Hz, 1
J ϭ 2.1 Hz, 1 H, 6-H), 6.66 (d, J ϭ 2.1 Hz, 1 H, 8-H), 6.87 (d, J ϭ H, β-H), 7.73 (dd, J ϭ 7.3, 1.6 Hz, 2 H, 2Ј,6Ј-H), 10.9 (br. s, 1 H,
15.9 Hz, 1 H, α-H), 6.95 (d, J ϭ 8.8 Hz, 2 H, 3ЈЈ,5ЈЈ-H), 6.95 (d, 7-OH), 12.86 (br. s, 1 H, 5-OH) ppm. 13C NMR ([D6]DMSO): δ ϭ
J ϭ 8.7 Hz, 2 H, 3Ј,5Ј-H), 7.11 (d, J ϭ 16.1 Hz, 1 H, αЈ-H), 94.0 (C-8), 98.8 (C-6), 104.1 (C-10), 108.3 (C-3), 120.1 (C-α), 127.9
7.27Ϫ7.52 (m, 24 H, 2Ј,6Ј,2ЈЈ,6ЈЈ-H and 2,3,4,5,6-H of 5,7,4Ј,4ЈЈ-
(C-2Ј,6Ј), 129.1 (C-3Ј,5Ј), 130.0 (C-4Ј), 134.9 (C-1Ј), 136.9 (C-β),
Eur. J. Org. Chem. 2003, 4575Ϫ4585
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4583

C. M. M. Santos, A. M. S. Silva, J. A. S. Cavaleiro
FULL PAPER
157.3 (C-9), 161.6 (C-5), 162.3 (C-2), 164.4 (C-7), 181.7 (C-4) ppm. 279 (25), 267 (9), 249 (9), 221 (8), 187 (9), 176 (17), 160 (18), 137
EI-MS: m/z (rel. int.) ϭ 280 (100) (Mϩ·), 279 (89), 262 (20), 251
(58), 114 (12), 84 (32), 66 (38), 63 (8), 52 (6), 51 (8). C17H12O5
(8), 234 (6), 165 (5), 153 (19), 128 (38), 124 (18), 102 (8), 77 (9), 69 (296.3): calcd. C 68.92, H 4.08; found C 68.99, H 4.23.
(15), 63 (4), 51 (8). C17H12O4 (280.3): calcd. C 72.85, H 4.32; found
5,3Ј,4Ј-Trihydroxy-2-styrylchromone (5h): Yield 55.0 % (407 mg).
M.p. 275Ϫ276 °C (recrystallised from a mixture of ethanol and
C 72.84, H 4.10.
water). 1H NMR ([D6]DMSO): δ ϭ 6.47 (s, 1 H, 3-H), 6.78 (d, J ϭ
8.2 Hz, 1 H, 6-H), 6.81 (d, J ϭ 8.1 Hz, 1 H, 5Ј-H), 6.88 (d, J ϭ
16.1 Hz, 1 H, α-H), 7.02 (br. d, J ϭ 8.1 Hz, 1 H, 6Ј-H), 7.12 (d,
J ϭ 8.2 Hz, 1 H, 8-H), 7.13 (d, J ϭ 2.7 Hz, 1 H, 2Ј-H), 7.59 (d,
J ϭ 16.1 Hz, 1 H, β-H), 7.64 (t, J ϭ 8.2 Hz, 1 H, 7-H), 9.23 (br. s,
1 H, 3Ј-OH), 9.69 (br. s, 1 H, 4Ј-OH), 12.80 (s, 1 H, 5-OH) ppm.
13C NMR ([D6]DMSO): δ ϭ 107.2 (C-8), 107.4 (C-3), 110.2 (C-
10), 110.8 (C-6), 114.5 (C-2Ј), 115.9 (C-5Ј), 116.1 (C-α), 121.3 (C-
6Ј), 126.4 (C-1Ј), 135.7 (C-7), 138.7 (C-β), 145.7 (C-3Ј), 148.4 (C-
4Ј), 155.7 (C-9), 160.0 (C-5), 164.1 (C- 2), 182.9 (C-4) ppm. EI-MS:
m/z (rel. int.) ϭ 296 (100) [Mϩ·], 295 (63), 279 (25), 267 (7), 249
(11), 221 (8), 186 (7), 176 (8), 160 (40), 137 (65), 114 (20), 108 (17),
88 (7), 77 (9), 63 (8), 52 (9), 51 (10). C17H12O5 (296.3): calcd. C
68.92, H 4.08; found C 68.86, H 4.30.
7,4Ј-Dihydroxy-2-styrylchromone (5d): Yield 86.0 % (602 mg). M.p.
306Ϫ307 °C (recrystallised from a mixture of ethanol and water).
1H NMR ([D6]DMSO): δ ϭ 6.25 (s, 1 H, 3-H), 6.83 (d, J ϭ 8.6 Hz,
2 H, 3Ј,5Ј-H), 6.88 (dd, J ϭ 8.7, 2.2 Hz, 1 H, 6-H), 6.92 (d, J ϭ
2.2 Hz, 1 H, 8-H), 6.92 (d, J ϭ 16.2 Hz, 1 H, α-H), 7.55 (d, J ϭ
16.2 Hz, 1 H, β-H), 7.56 (d, J ϭ 8.6 Hz, 2 H, 2Ј,6Ј-H), 7.83 (d, J ϭ
8.7 Hz, 1 H, 5-H), 9.98 (br. s, 1 H, 4Ј-OH), 10.78 (br. s, 1 H, 7-
OH) ppm. 13C NMR ([D6]DMSO): δ ϭ 102.4 (C-8), 108.8 (C-3),
114.6 (C-6), 115.9 (C-3Ј,5Ј), 116.4 (C-10), 117.1 (C-α), 126.3 (C-
1Ј), 126.6 (C-5), 129.7 (C-2Ј,6Ј), 136.1 (C-β), 157.3 (C-9), 159.2 (C-
4Ј), 161.8 (C-2), 162.7 (C-7), 176.3 (C-4) ppm. EI-MS: m/z (rel.
int.) ϭ 280 (100) [Mϩ·], 279 (97), 263 (45), 251 (15), 234 (5), 223
(5), 171 (7), 144 (25), 137 (38), 126 (11), 115 (38), 108 (10), 89 (7),
84 (34), 66 (40), 63 (8), 52 (8), 51 (8). C17H12O4 (280.3): calcd. C
72.85, H 4.32; found C 72.54, H 4.42.
5,7,3Ј,4Ј-Tetrahydroxy-2-styrylchromone
(5i):
Yield
27.1 %
5,4Ј-Dihydroxy-2-styrylchromone (5e): Yield 63.0 % (441 mg). M.p.
278Ϫ280 °C (recrystallised from a mixture of ethanol and water).
1H NMR ([D6]DMSO): δ ϭ 6.44 (s, 1 H, 3-H), 6.78 (d, J ϭ 8.2 Hz,
1 H, 6-H), 6.84 (d, J ϭ 8.6 Hz, 2 H, 3Ј,5Ј-H), 6.99 (d, J ϭ 16.1 Hz,
1 H, α-H), 7.11 (dd, J ϭ 8.2, 0.7 Hz, 1 H, 8-H), 7.59 (d, J ϭ 8.6 Hz,
2 H, 2Ј,6Ј-H), 7.65 (t, J ϭ 8.2 Hz, 1 H, 7-H), 7.66 (d, J ϭ 16.1 Hz,
1 H, β-H), 10.10 (br. s, 1 H, 4Ј-OH), 12.79 (s, 1 H, 5-OH) ppm.
13C NMR ([D6]DMSO): δ ϭ 107.2 (C-8), 107.4 (C-3), 110.2 (C-
10), 110.8 (C-6), 116.0 (C-3Ј,5Ј), 116.2 (C-α), 125.9 (C-1Ј), 130.0
(C-2Ј,6Ј), 135.8 (C-7), 138.3 (C-β), 155.7 (C-9), 159.7 (C- 4Ј), 160.0
(C-5), 164.1 (C-2), 182.9 (C-4) ppm. EI-MS: m/z (rel. int.) ϭ 280
(100) [Mϩ·], 279 (81), 262 (36), 251 (11), 234 (7), 205 (6), 171 (6),
144 (41), 137 (33), 126 (7), 115 (36), 108 (19), 89 (8), 63 (8), 52 (8),
51 (8). C17H12O4 (280.3): calcd. C 72.85, H 4.32; found C 72.68,
H 4.35.
(211 mg). M.p. 304Ϫ306 °C (recrystallised from a mixture of etha-
nol and water). H NMR ([D6]DMSO): δ ϭ 6.17 (d, J ϭ 2.0 Hz,
1
1 H, 6-H), 6.32 (s, 1 H, 3-H), 6.45 (d, J ϭ 2.0 Hz, 1 H, 8-H), 6.79
(d, J ϭ 8.2 Hz, 1 H, 5Ј-H), 6.82 (d, J ϭ 16.0 Hz, 1 H, α-H), 7.02
(dd, J ϭ 8.2, 2.0 Hz, 1 H, 6Ј-H), 7.10 (d, J ϭ 2.0 Hz, 1 H, 2Ј-H),
7.51 (d, J ϭ 16.0 Hz, 1 H, β-H), 9.20 (br. s, 1 H, 3Ј-OH), 9.64 (br.
s, 1 H, 4Ј-OH), 10.85 (br. s, 1 H, 7-OH), 12.96 (br. s, 1 H, 5-OH)
ppm. 13C NMR ([D6]DMSO): δ ϭ 93.9 (C-8), 98.7 (C-6), 104.0 (C-
10), 107.0 (C-3), 114.4 (C-2Ј), 115.9 (C-5Ј), 116.2 (C-α), 121.1 (C-
6Ј), 126.5 (C-1Ј), 137.7 (C-β), 145.7 (C-3Ј), 148.1 (C-4Ј), 157.2 (C-
9), 161.5 (C-5), 163.2 (C-2), 164.2 (C-7), 181.7 (C-4) ppm. EI-MS:
m/z (rel. int.) ϭ 312 (13) [Mϩ·], 311 (9), 295 (2), 281 (3), 191 (10),
160 (4), 153 (8), 146 (35), 122 (3), 91 (4), 78 (85), 63 (100), 51 (2).
C17H12O6 (312.3): calcd. C 65.39, H 3.87; found C 65.53, H 4.07.
5,7,4Ј-Trihydroxy-2-styrylchromone (5f): Yield 50.0 % (370 mg).
M.p. 225Ϫ226 °C (recrystallised from a mixture of ethanol and
water). H NMR [(CD3)2CO]: δ ϭ 6.22 (s, 1 H, 3-H), 6.24 (s, 1 H,
Acknowledgments
1
6-H), 6.49 (s, 1 H, 8-H), 6.92 (d, J ϭ 8.8 Hz, 2 H, 3Ј,5Ј-H), 6.92
(d, J ϭ 15.9 Hz, 1 H, α-H), 7.60 (d, J ϭ 8.8 Hz, 2 H, 2Ј,6Ј-H), 7.64
(d, J ϭ 15.9 Hz, 1 H, β-H), 13.01 (s, 1 H, 5-OH) ppm. 13C NMR
[(CD3)2CO]: δ ϭ 93.3 (C-8), 98.2 (C-6), 104.2 (C-10), 106.8 (C-3),
115.4 (C-3Ј,5Ј), 116.2 (C-α), 126.4 (C-1Ј), 129.3 (C-2Ј,6Ј), 136.8 (C-
β), 157.3 (C-9), 159.0 (C-4Ј), 162.1 (C-5), 162.8 (C-2), 163.6 (C-7),
181.7 (C-4) ppm. EI-MS: m/z (rel. int.) ϭ 296 (100) [Mϩ·], 295 (98),
279 (32), 267 (15), 250 (7), 241 (6), 213 (8), 171 (9), 165 (17); 153
(44), 144 (37), 134 (18), 123 (12), 115 (39), 96 (7), 91 (10), 78 (7),
69 (21), 55 (6), 51 (5). C17H12O5 (296.3): calcd. C 68.92, H 4.08;
found C 68.98, H 4.05.
Sincere thanks are expressed to the University of Aveiro and ‘‘Fun-
ˆ
dac¸a˜o para a Ciencia e a Tecnologia’’, Portugal, for funding the
Organic Chemistry Research Unit. One of us (CMMS) also thanks
the University of Aveiro for the award of a MSc grant.
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7,3Ј,4Ј-Trihydroxy-2-styrylchromone (5g): Yield 80.0 % (592 mg).
M.p. 310Ϫ311 °C (recrystallised from a mixture of ethanol and
water). 1H NMR ([D6]DMSO): δ ϭ 6.27 (s, 1 H, 3-H), 6.79 (d, J ϭ
8.2 Hz, 1 H, 5Ј-H), 6.82 (d, J ϭ 16.1 Hz, 1 H, α-H), 6.86 (dd, J ϭ
8.7, 2.2 Hz, 1 H, 6-H), 6.93 (d, J ϭ 2.2 Hz, 1 H, 8-H), 7.02 (dd,
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(d, J ϭ 16.1 Hz, 1 H, β-H), 7.83 (d, J ϭ 8.7 Hz, 1 H, 5-H), 10.8
(br. s, 1 H, 7-OH) ppm. 13C NMR ([D6]DMSO): δ ϭ 102.4 (C-8),
108.8 (C-3), 114.3 (C-2Ј), 114.6 (C-6), 115.8 (C-5Ј), 116.4 (C-10),
116.9 (C-α), 120.8 (C-6Ј), 126.5 (C-5), 126.7 (C-1Ј), 136.4 (C-β),
145.7 (C-3Ј), 147.8 (C-4Ј), 157.3 (C-9), 161.8 (C-2), 162.6 (C-7),
176.3 (C-4) ppm. EI-MS: m/z (rel. int.) ϭ 296 (100) [Mϩ·], 295 (58),
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 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 4575Ϫ4585

Synthesis of New Hydroxy-2-styrylchromones
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