Wittig reactions of chromone-3-carboxaldehydes with benzylidenetriphenyl phosphoranes: A new synthesis of 3-styrylchromones

Article abstract of DOI:10.1039/b303554a

An efficient route to 3-styrylchromones has been developed and applied to syntheses of several new derivatives. Wittig reactions of chromone-3- carboxaldehydes with some benzylic ylides gave a diastereomeric mixture of (E) and (Z)-3-styrylchromones that a

Full text of DOI:10.1039/b303554a

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Wittig reactions of chromone-3-carboxaldehydes with
benzylidenetriphenyl phosphoranes: a new synthesis of
3-styrylchromones
´
Angela Sandulache, Artur M. S. Silva,* Diana C. G. A. Pinto, Lucia M. P. M. Almeida
´
and Jose A. S. Cavaleiro*
Department of Chemistry, University of Aveiro, 3810-193, Aveiro, Portugal.
Fax: 351 234 370084; E-mail: arturs@dq.ua.pt and jcavaleiro@dq.ua.pt
Received (in Montpellier, France) 28th March 2003, Accepted 5th August 2003
First published as an Advance Article on the web 3rd September 2003
An efficient route to 3-styrylchromones has been developed and applied to syntheses of several new derivatives.
Wittig reactions of chromone-3-carboxaldehydes with some benzylic ylides gave a diastereomeric mixture of (E)
and (Z)-3-styrylchromones that are separable by thin layer chromatography. The (Z)-isomers were the most
abundant diastereomers independent of having electron-withdrawing or electron-donating substituents on the
phenyl ring. Stereochemistry of the obtained diastereomers was established using NOESY experiments.
an attempt to prepare 3-styrylchromones unsubstituted at the
=
Introduction
vinylic system Ca Cb, very complex mixtures were obtained.
Styrylchromones constitute a small group of oxygen heterocy-
clic compounds which have shown significant biological acti-
vities.1 The synthesis of 2-styrylchromones have been
extensively studied,2 whereas to our knowledge only a few syn-
thetic methods are available for the preparation of their iso-
mers, 3-styrylchromones.3–7 One of them involves the Heck
reaction of 3-bromochromone with styrene, in the presence
of palladium acetate, tri-o-tolylphosphine and triethylamine
in DMF, and has only been used for the formation of unsub-
stituted (E)-3-styrylchromone.3 The application of this proce-
dure to polybrominated chromone derivatives would lead to
the coupling of several alkenes to the chromone system at
the halogenated sites. Another synthetic possibility was used
to prepare (E)-2-methyl-3-(30,50-dihydroxystyryl)chromone
from the Wittig reaction of an appropriate phosphonium salt
with a benzaldehyde derivative.4 The preparation of the
required phosphonium salt involves a selective monobromina-
tion of 3-methylchromones, a procedure that often gives
by-products. A third synthetic method consists in the conden-
sation of chromone-3-carboxaldehydes with 2,4-dinitrotoluene
in pyridine.5 New and simple (E)-3-styrylchromones have been
obtained, in moderate yields (45–58%), with this synthetic pro-
cedure. Some 3-styrylchromone type-compounds have been
obtained from the condensation of chromone-3-carboxalde-
hydes with 6,8-dimethylcoumarin 4-acetic acid in pyridine.6
The structural characterisation of the obtained chromones
showed that the carboxyl group was missing, suggesting that
a decarboxylation took place during the condensation of the
active methylene group. The last synthetic method consists in
the oxidative rearrangement of (E,E)-g-alkyl-20-hydroxycinna-
mylideneacetophenones, with thallium(III) trinitrate, into the
corresponding acetal derivatives, 3-alkyl-4-aryl-1-(2-hydroxy-
phenyl)-2-(dimethoxymethyl)-3-buten-1-ones, which cyclise
into the corresponding (E)-3-(a-alkylstyryl)chromones by
treatment with hydrochloric acid.7 This method has been
developed in our laboratory and gave rise stereoselectively to
the (E)-isomers, but it also has some limitations. It uses very
toxic reagents, such as thallium trinitrate(III), and only 3-
(a-alkylstyryl)chromones could be obtained. Furthermore, in
Taking into account the potential uses of 3-styrylchromones
and the need for having efficient synthetic methodologies for
their syntheses, we report here work carried out on syntheses
of these compounds from the Wittig reaction of chromone-3-
carboxaldehyde derivatives with benzylic ylides.
The use of chromone-3-carboxaldehydes in the synthesis of
heterocyclic systems has attracted the attention of many
researchers, since their convenient synthesis was reported in
the 1970’s.8 Much of the synthetic utility of this type of
compounds derives from the reactivity of its electron deficient
centres at C-2, C-4 and 3-formyl group. Chromone-3-carbox-
aldehydes can act as Michael acceptors, but also they can be
used as heterodienes or dienophiles in cycloaddition reac-
tions.8,9 We have studied their reactivity in Wittig reactions
with benzylic ylides (semi-stabilised ylides), and as a result,
the establishment of a new synthetic method for (E)- and
(Z)-3-styrylchromones has been set up. The influence of the
substituents of the benzylic ylides and the chromone nucleus
on reaction yields and (E : Z) isomeric ratios will also be
discussed.
Results and discussion
Chemistry
Initial experiments considered the reaction of benzylidenetri-
phenylphosphorane 2a with chromone-3-carboxaldehyde 1a.
Thus a THF suspension of benzyl triphenylphosphonium
chloride was treated with a molar equivalent of sodium
hydride; the solution became orange in colour (2 h), suggesting
ylide formation. After the addition of a molar equivalent of
chromone-3-carboxaldehyde 1a to this ylide, and refluxing
the reaction mixture for 24 h, it became yellow in colour. Thin
layer chromatography (TLC) analysis of this reaction mixture
revealed the presence of starting material and of two new
products. Spectroscopic evidence of such compounds led us
to assign its structure as (E)-3-styrylchromone 3a (2%) and
(Z)-3-styrylchromone 4a (30%). Since that yield was not
satisfactory, certain changes were made in the experimental
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New J. Chem., 2003, 27, 1592–1598
DOI: 10.1039/b303554a
This journal is # The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2003

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3
procedure including time for the ylide formation and the molar
quantity of base used (Table 1). We found that better condi-
tions are those described in entry 5 of Table 1: 3 h for ylide for-
mation, 1 equiv. of sodium hydride as base and 40 h for the
reaction of the formed ylide with the carbonyl compound.
Both (E and Z) diastereomers, 3a and 4a, were obtained in
all the assays described in Table 1, the (Z) isomer being the
most abundant, as expected for the reaction of semi-stabilised
ylides with steric crowded carbonyl compounds10 (Scheme 1).
After the establishment of optimised experimental condi-
tions for the reaction of 1a with 2a (last entry of Table 1),
we carried out the Wittig reaction of chromone-3-carboxalde-
hydes 1a–c with ylides 2a–d, obtaining a diastereomeric mix-
ture of 3-styrylchromones, 3a–l and 4a–l (Table 2, Scheme
1). The (Z) isomer was the most abundant diastereomer inde-
pendently of the starting ylide structure and of the carbonyl
compound.
Our results suggest that the formation of ylide 2d, bearing
electron-donating substituents on the phenyl ring, is much fas-
ter than the others since the solution became orange in colour
5 min after the addition of base. Longer reaction times led to
the decomposition of such an ylide, an observation based on
the decoloration of the reaction medium. These data can be
explained taking into account that ylides 2a–c, bearing elec-
tron-neutral or electron-withdrawing groups on the phenyl
ring, are more stable than ylide 2d, allowing us to predict their
quantitative formation. In the case of ylide 2d, this is not
possible due to the higher reactivity. Thus, the addition of
chromone-3-carboxaldehydes 1a–c must be done as soon as
it is formed (but not in a quantitative way).
pling constant values of JHa–Hb ¼ 12.0–12.1 Hz indicate a
cis configuration of these vinylic systems. The stereochemistry
of these compounds 4a–l was also established by 2D NOESY
experiments. Strong NOE cross peaks were observed between
H-a and H-b and also between H-b and H-20,60, while a
weak cross peak between H-2 and H-20,60 was also observed.
These results allowed us to confirm the cis configuration of
=
the Ca Cb double bonds and also to establish the conforma-
tion of the styryl moiety relative to the chromone nucleus
as depicted in Scheme 1. The coupling constant value
4JH2-Ha ¼ 0.9–1.2 Hz suggests a Z-(sE)-Z geometry for this
moiety of the molecule.
The connectivities found in the HMBC spectra of 3-styryl-
chromones 3a–l and 4a–l allowed an unequivocal assignment
of quaternary carbon resonances and confirmation of proto-
nated carbons ones, which were assigned from the correlations
found in their HSQC spectra. The connectivities found in these
HMBC spectra for H-2 and H-5 (for 5-unsubstituted com-
pounds) played an important role in the assignment of carbon
resonances of C-3, C-9 and C-a (and indirectly of the H-a
proton resonance, from the HSQC spectra), (Fig. 1). The
connectivities found for H-a (with C-2, C-4, C-10 and C-b)
and H-b (with C-3 and C-20,60) also support the assignment
of these proton resonances.
Conclusion
Wittig reactions of chromone-3-carboxaldehydes with several
benzylic ylides have been investigated and a new synthetic
procedure for the synthesis of 3-styrylchromones has been
established. These reactions led to a diasteromeric mixture of
(E)- and (Z)-3-styrylchromones with the (Z)-isomers being
the most abundant ones. The stereochemistry of these isomers
was also established.
Wittig reactions of ylides 2a–d and chromone-3-carboxalde-
hydes 1a,b have also been carried out using n-butyllithium
instead of sodium hydride in the formation of ylides (Vide
experimental). The obtained results were more or less the
same with a diastereomeric mixture of 3-styrylchromones
3a,b,d,e,g,h,j,k and 4a,b,d,e,g,h,j,k attained in approximately
the same yield as that when sodium hydride was used as base
and with the (Z) isomer being the most abundant one.
Experimental
Melting points were determined on a Reichert Thermovar
apparatus fitted with a microscope and are uncorrected.
NMR spectra were recorded on Bruker DRX 300 spectrometer
NMR spectroscopy
1
(300.13 MHz for H and 75.47 MHz for 13C), with CDCl3 as
1
Most important features of the H NMR spectra of 3-styryl-
chromones 3a–l and 4a–l are the resonances of their vinylic
protons. In the case of (E)-isomers 3a–l these resonances
solvent if not stated otherwise. Chemical shifts (d) are reported
in ppm values and coupling constants (J) in Hz. The internal
standard was TMS. 1H Assignments were made using 2D
gCOSY and NOESY (mixing time of 800 ms) experiments,
while 13C assignments were made using 2D gHSQC and
gHMBC experiments (long range C/H coupling constants
were optimised to 7 Hz). Mass spectra (EI, 70 eV) were
measured on a VG Autospec Q and M mass spectrometers.
IR spectra were obtained in KBr pellets on a MATTSON
7000 FTIR spectrometer. Elemental analyses were obtained
with a LECO 932 CHN analyser (University of Aveiro).
Preparative thin layer chromatography was carried out with
Riedel silica gel 60 DGF254 , and column chromatography
using Merck silica gel 60, 70–230 mesh.
appear at d ¼ 6.85–7.32 (H-a), 7.50–7.94 (H-b) and 7.94–
8.1411 (H-2). The coupling constant values of JHa–Hb
¼
3
16.1–16.4 Hz indicate a trans configuration of these vinylic
systems. The intense NOE cross peaks between H-2 and H-a
and H-b observed in their 2D NOESY experiments demon-
strate the existence of a free rotation around the C3–Ca bond.
In the 1H NMR spectra of (Z)-3-styrylchromones 4a–l,
the proton resonances of H-a, H-b, and H-2, appear at d
6.40–6.71, 6.67–6.90 and 7.47–7.80,11 respectively. The cou-
Table 1 Wittig reaction of chromone-3-carboxaldehyde 1a with
benzylic ylide 2a
3-Formylchromones 1a,b were obtained from Sigma-
Aldrich while 3-formyl-5-methoxychromone 1c was obtained
as described in the literature.12 All other chemicals and sol-
vents used were obtained from commercial sources and used
as received or dried using standard procedures.
Reaction time
before the
Reaction time
Equiv molar after the
addition of 1a (%) (E/Z)
Yielda
Entry addition of 1a of NaH
1
2
3
4
5
2 h
2 h
3 h
3 h
3 h
1 equiv.
1 equiv.
1 equiv.
1.5 equiv.
1 equiv.
24 h
40 h
24 h
24h
2/30
6/35
6/38
3/46
4/50
Wittig reactions: general procedure for the synthesis of
3-styrylchromones (3a–l and 4a–l)
Method A–using sodium hydride. Sodium hydride (25 mg,
1.04 mmol) was added to a suspension of the appropriate
phosphonium halide (1.04 mmol) in dry THF (25 mL),
under nitrogen, and the reaction mixture was refluxed with
stirring for the adequate time (as mentioned in Table 2). The
40 h
a
Yields and (E : Z) ratios are based on preparative TLC isolated
amounts.
New J. Chem., 2003, 27, 1592–1598
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Scheme 1 Synthesis of (E)- and (Z)-3-styrylchromones.
appearance of orange colour and the disappearance of the sus-
with mixtures of light petroleum–dichloromethane, leading to
pension of phosphonium salts indicated the ylide formation.
After that period, the appropriate chromone-3-carboxalde-
hydes 1a–c (1.04 mmol) were added and the reaction mixture
refluxed for the appropriate time, as mentioned in Table 2.
The solvent was removed and the residue dissolved in dichloro-
methane (20 mL) and analysed by thin-layer chromatogra-
phy. The TLC plates were eluted several times with mixtures
of light petroleum:dichloromethane, leading to the isolation
of two main spots, in each case. The component of high Rf
spot was identified as being (E)-3-styrylchromones 3a–l,
whereas the other spot was constituted by (Z)-3-styrylchro-
mone 4a–l (total yields in Table 1). These compounds were
recrystallised from ethanol.
the isolation of two main spots, in each case. The component
of high Rf spot was identified as being (E)-3-styrylchromones
3a,b,d,e,g,h,j,k (5–18%), whereas the other spot was consti-
tuted by (Z)-3-styrylchromone 4a,b,d,e,g,h,j,k (45–64%). These
compounds were recrystallised from ethanol.
(E)-3-Styrylchromone (3a). Mp 168–169 ꢁC (recrystallised
from ethanol, lit.3 170–171 C). IR n ¼ 1644 (C O), 1615
ꢁ
=
1
(C C), 1560, 1465, 1408, 1358, 1312, 1182, 972, 749, 695. H
=
NMR d ¼ 7.00 (d, 1 H, J ¼ 16.3 Hz, H-a), 7.24–7.29 (m, 1
H, H-40), 7.36 (t, 2 H, J ¼ 7.4 Hz, H-30,50), 7.43 (ddd, 1 H,
J ¼ 8.0, 7.1 and 0.8 Hz, H-6), 7.47 (d, 1 H, J ¼ 8.7 Hz, H-
8), 7.53 (d, 2 H, J ¼ 7.4 Hz, H-20,60), 7.64 (d, 1 H, J ¼ 16.3
Hz, H-b), 7.68 (ddd, 1 H, J ¼ 8.7, 7.1 and 1.6 Hz, H-7), 8.12
(s, 1 H, H-2), 8.31 (dd, 1 H, J ¼ 8.0 and 1.6 Hz, H-5). 13C
NMR d ¼ 118.0 (C-8), 119.0 (C-a), 121.8 (C-3), 124.1 (C-
10), 125.2 (C-6), 126.2 (C-5), 126.6 (C-20,60), 127.8 (C-40),
128.6 (C-30,50), 131.7 (C-b), 133.5 (C-7), 137.3 (C-10), 153.0
(C-2), 155.8 (C-9), 176.6 (C-4). EI-MS: m/z (rel. int.) 249
Method B–using n-butyllithium. A cyclohexane solution of n-
butyllithium (0.61 mL, 1.25 mmol) was added to a suspension
of the appropriate phosphonium halide (1.04 mmol) in dry
THF (25 mL) and kept under nitrogen at ꢀ60 ꢁC. The reaction
mixture was stirred at this temperature until the appearance of
an intense orange colour, and the disappearance of the suspen-
sion of phosphonium salts (30 min to 1 h for ylides 2a–c and 15
min for ylide 2d) and the temperature allowed rising to room
temperature. After this period, chromone-3-carboxaldehydes
1a,b (1.04 mmol) were added and the reaction mixture refluxed
for 24 h. The solvent was removed and the residue was dis-
solved in dichloromethane (20 mL) and analysed by thin-layer
chromatography. The TLC plates were eluted several times
ꢂ
[(M + 1)+, 21], 248 (M+ , 100), 247 [(M ꢀ 1)+, 82], 231 (15),
219 (10), 171 (24), 155 (11), 128 (43), 127 (14), 124 (8), 121
(17), 120 (9), 105 (19), 102 (7), 92 (12), 85 (9), 83 (13), 77
ꢂ
(14). EI-HRMS (C17H12O2 [M+ ]), calcd. 248.0837; found:
248.0838.
(Z)-3-Styrylchromone (4a). Mp 129–130 ꢁC (recrystallised
=
=
from ethanol). IR n ¼ 1639 (C O), 1613 (C C), 1569, 1465,
1413, 1374, 1353, 1321, 1216, 1188, 1133, 925, 846, 754, 699.
1H NMR d ¼ 6.55 (dd, 1 H, J ¼ 12.1 and 0.9 Hz, H-a), 6.81
(d, 1 H, J ¼ 12.1 Hz, H-b), 7.21–7.32 (m, 5 H, H-20,30,40,50,60),
7.40 (d, 1 H, J ¼ 8.4 Hz, H-8), 7.42 (ddd, 1 H, J ¼ 8.1, 7.1
and 0.9 Hz, H-6), 7.66 (ddd, 1 H, J ¼ 8.4, 7.1 and 1.5 Hz,
H-7), 7.73 (d, 1 H, J ¼ 0.9 Hz, H-2), 8.29 (dd, 1 H, J ¼ 8.1
and 1.5 Hz, H-5). 13C NMR d ¼ 118.1 (C-8), 120.2 (C-a),
121.1 (C-3), 124.0 (C-10), 125.2 (C-6), 126.0 (C-5), 127.3 (C-
40), 128.5 and 128.6 (C-30,50 and C-20,60), 132.6 (C-b), 133.6
(C-7), 136.6 (C-10), 154.1 (C-2), 156.1 (C-9), 177.2 (C-4). EI-
Table 2 Wittig reactions of chromone-3-carboxaldehydes 1a–c with
ylides 2a–d
Reaction time
after the
addition of
Time
of ylide
Chromone-3- chromone-3-
Ylide carboxaldehydes formation carboxaldehydes (%) (E/Z)
Yielda
2a
2b
2c
2d
1a
1b
1c
1a
1b
1c
1a
1b
1c
1a
1b
1c
3 h
3 h
40 h
40 h
40 h
24 h
24 h
24 h
24 h
24 h
40 h
24 h
24 h
24 h
4/50
7/68
5/52
5/56
5/57
7/54
8/67
5/68
4/67
6/66
4/70
8/58
ꢂ
MS: m/z (rel. int.) 249 [(M + 1)+, 28], 248 (M+ , 100), 247
[(M ꢀ 1)+, 86], 231 (23), 219 (19), 191 (10), 189 (11), 171
3 h
3 h
3 h
3 h
3 h
3 h
3 h
5 min
5 min
5 min
a
Yields and (E : Z) ratios are based on preparative TLC isolated
amounts.
Fig. 1 Important connectivities found in the HMBC spectra of
3-styrylchromones 3a–1 and 4a–1.
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110.1 (C-8), 114.7 (C-10), 120.7 (C-a), 122.2 (C-3), 127.2 (C-
(41), 155 (22), 129 (12), 128 (64), 127 (29), 126 (9), 124 (8), 121
(24), 120 (16), 110 (15), 102 (18), 92 (28), 77 (15). Anal. calcd.
for C17H12O2 : C 82.25, H 4.87; found: C 82.35, H 4.79%.
40), 128.6 (C-20,30,50,60), 132.1 (C-b), 133.6 (C-7), 136.8 (C-10),
152.1 (C-2), 158.1 (C-9), 160.0 (C-5), 176.8 (C-4). EI-MS:
m/z (rel. int.) ¼ 279 [(M + 1)+, 30], 278 (M+ꢂ, 100), 277
[(M ꢀ 1)+, 26], 263 (71), 262 (10), 261 (6), 250 (8), 249 (25),
247 (20), 231 (16), 201 (21), 171 (11), 160 (12), 159 (72), 151
(9), 150 (17), 139 (12), 128 (30), 127 (18), 122 (16), 121 (24),
115 (13), 107 (33), 102 (11), 91 (32), 77 (11). EI-HRMS
(E)-6-Methyl-3-styrylchromone (3b). Mp 151–152 ꢁC
=
(recrystallised from ethanol). IR n ¼ 3020, 1641 (C O), 1615
=
(C C), 1563, 1484, 1349, 1311, 1301, 1267, 1162, 980, 972,
1
832, 747, 688. H NMR d ¼ 2.47 (s, 3 H, 6-CH3), 7.00 (dd,
ꢂ
1 H, J ¼ 16.2 and 0.6 Hz, H-a), 7.24-7.29 (m, 1 H, H-40),
7.35 (d, 2 H, J ¼ 7.3 Hz, H-30,50), 7.36 (d, 1 H, J ¼ 8.6 Hz,
H-8), 7.48 (dd, 1 H, J ¼ 8.6 and 2.2 Hz, H-7), 7.53 (d, 2 H,
J ¼ 7.3 Hz, H-20,60), 7.60 (d, 1 H, J ¼ 16.2 Hz, H-b), 8.07
(d, 1 H, J ¼ 2.2 Hz, H-5), 8.10 (s br, 1 H, H-2). 13C NMR
d ¼ 21.0 (6-CH3), 117.8 (C-8), 119.1 (C-a), 121.6 (C-3), 123.7
(C-10), 125.5 (C-5), 126.6 (C-20,60), 127.8 (C-40), 128.6 (C-
30,50), 131.3 (C-b), 134.8 (C-7), 135.2 (C-6), 137.4 (C-10),
152.9 (C-2), 154.1 (C-9), 176.7 (Cꢂ-4). EI-MS: m/z (rel.
int.) ¼ 263 [(M + 1)+, 28], 262 (M+ , 100), 261 [(M ꢀ 1)+,
80], 245 (22), 233 (13), 185 (41), 155 (16), 135 (22), 134 (35),
131 (14), 128 (46), 127 (22), 115 (11), 106 (18), 105 (15), 103
(14), 89 (10), 78 (28), 77 (24). Anal. calcd. for C18H14O2 : C
82.42, H 5.38; found: C 82.16, H 5.21%.
(C18H14O3 [M+ ]): calcd. 278.0943, found 278.0956.
(E)-40-Chloro-3-styrylchromone (3d). Mp 159–160 ꢁC
=
(recrystallised from ethanol). IR n ¼ 1642 (C O), 1616
=
(C C), 1612, 1561, 1489, 1467, 1408, 1361, 1308, 1289, 1161,
1094, 973, 861, 816, 758, 693. 1H NMR d ¼ 6.93 (dd, 1 H,
J ¼ 16.2 and 0.7 Hz, H-a), 7.32 (d, 2 H, J ¼ 8.4, Hz, H-
30,50), 7.43 (dd, 1 H, J ¼ 7.8 and 6.8 Hz, H-6), 7.45 (d, 2 H,
J ¼ 8.4 Hz, H-20,60), 7.47 (d, 1 H, J ¼ 8.4 Hz, H-8), 7.64 (d,
1 H, J ¼ 16.2 Hz, H-b), 7.68 (ddd, 1 H, J ¼ 8.4, 6.8 and 1.7
Hz, H-7), 8.11 (s br, 1 H, H-2), 8.30 (dd, 1 H, J ¼ 7.8 and
1.7 Hz, H-5). 13C NMR d ¼ 118.0 (C-8), 119.7 (C-a), 121.5
(C-3), 124.1 (C-10), 125.3 (C-6), 126.2 (C-5), 127.7 (C-20,60),
128.8 (C-30,50), 130.5 (C-b), 133.4 (C-40), 133.6 (C-7), 135.9
(C-10), 153.3 (C-2), 155.8 (C-9), 176.6 (C-4).ꢂ EI-MS: m/z (rel.
(Z)-6-Methyl-3-styrylchromone (4b). Mp 60–62 ꢁC (recrys-
int.) ¼ 285 [(M + 1)+, 37Cl, 6], 284 (M+
281 [(M ꢀ 1)+, 35Cl, 58], 265 (13), 247 (22), 218 (6), 189 (15),
171 (30), 164 (10), 162 (28), 127 (27), 126 (11), 123 (8), 121
(18), 120 (12), 92 (20), 85 (8), 83 (11), 77 (10). Anal. calcd.
for C17H11O2Cl: C 72.22, H 3.92; found: C 72.16, H 4.07%.
,
37Cl, 40), 283
=
ꢂ
[(M ꢀ 1)+, 37Cl, (M + 1)+, 35Cl, 41], 282 (M+
,
35Cl, 100),
tallised from ethanol). IR n ¼ 3015, 1637 (C O), 1616
=
(C C), 1571, 1485, 1443, 1405, 1360, 1340, 1321, 1227, 1182,
1
1134, 925, 817, 798, 758, 699. H NMR d ¼ 2.44 (s, 3 H, 6-
CH3), 6.54 (dd, 1 H, J ¼ 12.1 and 1.0 Hz, H-a), 6.78 (d, 1
H, J ¼ 12.1 Hz, H-b), 7.19–7.31 (m, 5 H, H-20,30,40,50,60),
7.27 (d, 1 H, J ¼ 8.5 Hz, H-8), 7.44 (dd, 1 H, J ¼ 8.5 and
2.2 Hz, H-7), 7.69 (d, 1 H, J ¼ 1.0 Hz, H-2), 8.05 (d, 1 H,
J ¼ 2.2 Hz, H-5). 13C NMR d ¼ 20.8 (6-CH3), 117.8 (C-8),
120.3 (C-a), 120.8 (C-3), 123.5 (C-10), 125.2 (C-5), 127.2 (C-
40), 128.5 (C-20,30,50,60), 132.3 (C-b), 134.7 (C-7), 135.1 (C-6),
136.6 (C-10), 153.9 (C-2), 154.3 (C-9), 177.1 (C-4). EI-MS:
(Z)-40-Chloro-3-styrylchromone (4d). Mp 132–134 ꢁC
=
(recrystallised from ethanol). IR n ¼ 1640 (C O), 1607
=
(C C), 1569, 1488, 1463, 1375, 1350, 1319, 1211, 1186, 1136,
1
1086, 1012, 910, 852, 768, 685. H NMR d ¼ 6.55 (dd, 1 H,
ꢂ
m/z (rel. int.) ¼ 263 [(M + 1)+, 24], 262 (M+ , 100), 261
J ¼ 12.1 and 1.2 Hz, H-a), 6.75 (d, 1 H, J ¼ 12.1 Hz, H-b),
7.24 (s, 4 H, H-20,30,50,60), 7.42 (d, 1 H, J ¼ 7.6 Hz, H-8),
7.43 (ddd, 1 H, J ¼ 7.7, 7.3 and 0.9 Hz, H-6), 7.68 (dd, 1 H,
J ¼ 7.6 and 7.3 Hz, H-7), 7.72 (d, 1 H, J ¼ 1.2 Hz, H-2),
8.28 (d, 1 H, J ¼ 7.7 Hz, H-5). 13C NMR d ¼ 118.2 (C-8),
120.9 (C-3), 121.0 (C-a), 124.0 (C-10), 125.3 (C-6), 126.1 (C-
5), 128.8 (C-30,50), 129.9 (C-20,60), 131.5 (C-b), 133.1 (C-40),
133.7 (C-7), 135.0 (C-10), 154.0 (C-2), 156.1 (C-9), 177.0 (C-
[(M ꢀ 1)+, 81], 245 (20), 233 (11), 185 (39), 155 (12), 135
(17), 134 (29), 128 (42), 127 (19), 115 (8), 106 (15), 105 (12),
103 (10), 89 (7), 78 (25), 77 (18). Anal. calcd. for C18H14O2 :
C 82.42, H 5.38; found: C 82.20, H 5.42%.
(E)-5-Methoxy-3-styrylchromone (3c). Mp 147–148 ꢁC
=
(recrystallised from ethanol). IR n ¼ 1649 (C O), 1615
4). EI-MS: m/z (rel. int.) ¼ 285 [(M + 1)+, 37Cl, 12], 284
=
(C C), 1598, 1567, 1474, 1450, 1432, 1372, 1347, 1289, 1270,
ꢂ
(M+
,
,
37Cl, 47), 283 [(M ꢀ 1)+, 37Cl, (M + 1)+, 35Cl, 50], 282
35Cl, 100), 281 [(M ꢀ 1)+, 35Cl, 66], 265 (20), 247 (31),
1070, 895, 804, 780, 684. 1H NMR d ¼ 4.00 (s, 3 H, 5-
OCH3), 6.82 (d, 1 H, J ¼ 8.4 Hz, 6-H), 6.95 (d, 1 H,
J ¼ 16.3 Hz, H-a), 7.01 (dd, 1 H, J ¼ 8.4 and 0.7 Hz, H-8),
7.24-–7.28 (m, 1 H, H-40), 7.34 (t, 2 H, J ¼ 7.4 Hz, H-30,50),
7.50 (d, 2 H, J ¼ 7.4 Hz, H-20,60), 7.54 (t, 1 H, J ¼ 8.4 Hz,
H-7), 7.63 (d, 1 H, J ¼ 16.3 Hz, H-b), 7.97 (s, 1 H, 2-H).
13C NMR d ¼ 56.4 (5-OCH3), 106.4 (C-6), 110.0 (C-8),
114.7 (C-10), 119.1 (C-a), 122.7 (C-3), 126.5 (C-20,60), 127.7
(C-40), 128.6 (C-30,50), 131.2 (C-b), 133.5 (C-7), 137.6 (C-10),
151.1 (C-2), 157.8 (C-9), 160.2 (C-5), 176.3 (C-4). EI-MS:
ꢂ
(M+
219 (11), 218 (13), 191 (13), 189 (28), 171 (43), 164 (18), 163
(11), 162 (40), 127 (43), 126 (22), 123 (12), 121 (30), 120 (22),
115 (10), 101 (10), 92 (38), 77 (13). Anal. calcd. for
C17H11O2Cl: C 72.22, H 3.92; found: C 72.56, H 4.07%.
(E)-40-Chloro-6-methyl-3-styrylchromone (3e). Mp 162–
164 ꢁC (recrystallised from ethanol). IR n ¼ 3053, 1632
=
(C O), 1618 (C C), 1575, 1483, 1431, 1336, 1324, 1133,
=
ꢂ
1
m/z (rel. int.) ¼ 279 [(M + 1)+, 29], 278 (M+ , 100), 277
1088, 850, 837, 811, 794, 778. H NMR d ¼ 2.46 (s, 3 H, 6-
[(M ꢀ 1)+, 23], 262 (8), 250 (9), 249 (27), 247 (17), 231 (14),
201 (18), 171 (10), 160 (10), 159 (74), 150 (17), 139 (9), 128
(34), 127 (18), 122 (18), 121 (27), 115 (14), 107 (41), 102 (13),
92 (10), 91 (36), 77 (14). Anal. calcd. for C18H14O3 : C 77.68,
H 5.07; found: C 77.30, H 4.98%.
CH3), 6.92 (dd, 1 H, J ¼ 16.3 and 0.5 Hz, H-a), 7.30 (d, 2
H, J ¼ 8.5 Hz, H-30,50), 7.35 (d, 1 H, J ¼ 8.6 Hz, H-8), 7.43
(d, 2 H, J ¼ 8.5 Hz, H-20,60), 7.47 (dd, 1 H, J ¼ 8.6 and 2.2
Hz, H-7), 7.58 (d, 1 H, J ¼ 16.3 Hz, H-b), 8.06 (d, 1 H,
J ¼ 2.2 Hz, H-5), 8.07 (s br, 1 H, H-2). 13C NMR d ¼ 21.0
(6-CH3), 117.8 (C-8), 119.8 (C-a), 121.2 (C-3), 123.7 (C-10),
125.4 (C-5), 127.7 (C-20,60), 128.8 (C-30,50), 130.1 (C-b), 133.3
(C-40), 134.8 (C-7), 135.3 (C-6), 135.9 (C-10), 153.2 (C-2),
(Z)-5-Methoxy-3-styrylchromone (4c). Mp 83–84 ꢁC (recrys-
=
=
tallised from ethanol). IR n ¼ 1648 (C O), 1616 (C C), 1598,
1567, 1474, 1450, 1432, 1372, 1347, 1289, 1270, 1174, 895, 804,
154.0 (C-9), 176.6 (C-4). EI-MS: m/z (rel. int.) ¼ 299,
ꢂ
1
780, 684. H NMR d ¼ 3.91 (s, 3H, 5-OCH3), 6.44 (dd, 1 H,
[(M + 1)+ 37Cl, 10], 298 (M+
,
37Cl, 46), 297 [(M ꢀ 1)+, 37Cl,
ꢂ
J ¼ 12.1 and 1.1 Hz, H-a), 6.67 (d, 1 H, J ¼ 12.1 Hz, H-b),
6.72 (dd, 1 H, J ¼ 8.3 and 0.7 Hz, H-6), 6.84 (dd, 1 H,
J ¼ 8.6 and 0.7 Hz, H-8), 7.11–7.21 (m, 5 H, H-20,30,40,50,60),
7.42 (dd, 1 H, J ¼ 8.6 and 8.3 Hz, H-7), 7.47 (d, 1 H,
J ¼ 1.1 Hz, H-2). 13C NMR d ¼ 56.4 (5-OCH3), 106.3 (C-6),
(M + 1)+, 35Cl, 49], 296 (M+
,
35Cl, 100), 295 [(M ꢀ 1)+,
35Cl, 64], 279 (16), 261 (17), 189 (12), 185 (40), 162 (18), 148
(7), 135 (25), 134 (39), 127 (24), 126 (11), 106 (15), 105 (11),
78 (29), 77 (15). Anal. calcd. for C18H13ClO2 : C 72.85, H
4.42; found: C 72.71, H 4.03%.
New J. Chem., 2003, 27, 1592–1598
1595

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(Z)-40-Chloro-6-methyl-3-styrylchromone (4e). Mp 119–
120 ꢁC (recrystallised from ethanol). IR n ¼ 3053, 1632
H-2). 13C NMR (DMSO-d6) d ¼ 118.5 (C-8), 119.8 (C-3),
123.5 (C-10), 124.1 (C-30,50), 125.0 (C-a), 125.4 (C-5), 125.9
(C-6), 127.1 (C-20,60), 128.5 (C-b), 134.4 (C-7), 144.2 (C-10),
146.3 (C-40), 155.2 (C-2), 157.3 (C-9), 175.5 (C-4). EI-MS:
=
(C O), 1618 (C C), 1580, 1426, 1363, 1323, 1133, 1088,
=
1
1011, 837, 811, 794, 778. H NMR d ¼ 2.46 (s, 3 H, 6-CH3),
ꢂ
6.54 (dd, 1 H, J ¼ 12.1 and 1.0 Hz, H-a), 6.72 (d, 1 H,
J ¼ 12.1 Hz, H-b), 7.22 (s, 4 H, H-20,30,50,60), 7.29 (d, 1 H,
J ¼ 8.5 Hz, H-8), 7.47 (dd, 1 H, J ¼ 8.5 and 2.2 Hz, H-7),
7.69 (d, 1 H, J ¼ 1.0 Hz, H-2), 8.04 (d, 1 H, J ¼ 2.2 Hz, H-
5). 13C NMR d ¼ 20.9 (6-CH3), 117.8 (C-8), 120.7 (C-3),
121.1 (C-a), 123.5 (C-10), 125.2 (C-5), 128.7 (C-30,50), 129.9
(C-20,60), 131.2 (C-b), 132.9 (C-40), 134.9 (C-7), 135.0 and
m/z (rel. int.) ¼ 294 [(M + 1)+, 25], 293 (M+ , 100), 292
[(M ꢀ 1)+, 49], 276 (8), 263 (12), 247 (10), 246 (27), 218 (12),
200 (6), 189 (14), 171 (51), 128 (11), 127 (12), 121 (25), 120
(24), 115 (11), 92 (30), 77 (12). Anal. calcd. for C17H11NO4 :
C 69.62, H 3.78, N 4.78; found: C 69.54, H 3.92, N 4.76%.
(Z)-40-Nitro-3-styrylchromone (4g). Mp 151–152 ꢁC (recrys-
135.2 (C-10 and C-6), 153.8 (C-2), 154.3 (C-9), 176.9 (C-4).
tallised from ethanol). IR n ¼ 1638 (C O), 1612 (C C), 1593,
=
=
ꢂ
EI-MS: m/z (rel. int.) ¼ 299, [(M + 1)+ 37Cl, 7], 298 (M+
,
1567, 1513, 1463, 1374, 1336, 1319, 1218, 1138, 1102, 926, 855,
764, 681. H NMR (DMSO-d6) d ¼ 6.59 (dd, 1 H, J ¼ 12.1
37Cl, 37), 297 [(M ꢀ 1)+, 37Cl, (M + 1)+, 35Cl, 41], 296
1
ꢂ
(M+ ,35Cl, 100), 295 [(M ꢀ 1)+, 35Cl, 60], 279 (14), 261 (15),
and 0.9 Hz, H-a), 6.90 (d, 1 H, J ¼ 12.1 Hz, H-b), 7.51
(ddd, 1 H, J ¼ 8.0, 7.2 and 0.8 Hz, H-6), 7.57 (d, 2 H,
J ¼ 8.8 Hz, H-20,60), 7.63 (d, 1 H, J ¼ 8.1 Hz, H-8), 7.81
(ddd, 1 H, J ¼ 8.1, 7.2 and 1.5 Hz, H-7), 8.08 (dd, 1 H,
J ¼ 8.0 and 1.5 Hz, H-5), 8.12 (d, 2 H, J ¼ 8.8 Hz, H-30,50),
8.20 (d, 1 H, J ¼ 0.9 Hz, H-2). 13C NMR (DMSO-d6)
d ¼ 118.5 (C-8), 120.2 (C-3), 123.4 (C-10), 123.7 (C-30,50),
123.9 (C-a), 125.2 (C-5), 125.7 (C-6), 129.7 (C-20,60), 130.9
(C-b), 134.3 (C-7), 143.6 (C-10), 146.1 (C-40), 155.2 (C-2),
155.7 (C-9), 175.3 (C-4). EI-MS: m/z (rel. int.) ¼ 294
189 (10), 185 (43), 162 (18), 135 (24), 134 (41), 130 (10), 127
(21), 126 (10), 106 (14), 105 (9), 78 (19), 77 (15). Anal. calcd.
for C18H13ClO2 : C 72.85, H 4.42; found: C 73.12, H 4.34%.
(E)-40-Chloro-5-methoxy-3-styrylchromone (3f). Mp 161–
ꢁ
=
162 C (recrystallised from ethanol). IR n ¼ 1644 (C O),
=
1609 (C C), 1571, 1487, 1475, 1435, 1373, 1355, 1295, 1267,
1
1188, 1141, 1087, 1010, 918, 861, 818, 802, 774, 752, 684. H
NMR d ¼ 4.01 (s, 3 H, OCH3), 6.83 (d, 1 H, J ¼ 8.3, Hz,
H-6), 6.89 (d, 1 H, J ¼ 16.4 Hz, H-a), 7.02 (dd, 1 H, J ¼ 8.3
and 0.7 Hz, H-8), 7.30 (d, 2 H, J ¼ 8.4 Hz, H-30,50), 7.42 (d,
2 H, J ¼ 8.4 Hz, H-20,60), 7.55 (t, 1 H, J ¼ 8.3 Hz, H-7),
7.64 (d, 1 H, J ¼ 16.4 Hz, H-b), 7.96 (s, 1 H, H-2). 13C
NMR d ¼ 56.4 (OCH3), 106.4 (C-6), 110.0 (C-8), 114.7 (C-
10), 119.7 (C-a), 122.4 (C-3), 127.6 (C-20,60), 128.6 (C-30,50),
130.0 (C-b), 133.2 (C-40), 133.6 (C-7), 136.1 (C-10), 151.5 (C-
2), 157.8 (C-9), ꢂ160.2 (C-5), 176.3 (C-4). EI-MS: m/z (rel.
ꢂ
[(M + 1)+, 29], 293 (M+ , 100), 292 [(M ꢀ 1)+, 49], 276 (11),
263 (12), 247 (13), 246 (28), 218 (13), 200 (9), 189 (14), 171
(53), 146 (16), 127 (15), 126 (14), 121 (32), 120 (29), 115 (10),
92 (29), 78 (13), 77 (15). Anal. calcd. for C17H11NO4 : C
69.62, H 3.78, N 4.78; found: C 69.59, H 3.82, N 4.71%.
(E)-6-Methyl-40-nitro-3-styrylchromone (3h). Mp 225–
227 ꢁC (recrystallised from ethanol). IR n ¼ 3068, 1651
int.) ¼ 314 (M+
,
37Cl, 13), 313, [(M ꢀ 1)+ 37Cl, (M + 1)+,
(C O), 1615 (C C), 1592, 1561, 1507, 1463, 1335, 1318,
1300, 1267, 1159, 1105, 969, 869, 857, 763, 745, 699. 1H
NMR d ¼ 2.49 (s, 3 H, 6-CH3), 7.08 (dd, 1 H, J ¼ 16.2 and
0.5 Hz, H-a), 7.39 (d, 1 H, J ¼ 8.5 Hz, H-8), 7.51 (dd, 1 H,
J ¼ 8.5 and 2.2 Hz, H-7), 7.64 (d, 2 H, J ¼ 8.8 Hz, H-20,60),
7.84 (d, 1 H, J ¼ 16.2 Hz, H-b), 8.08 (d, 1 H, J ¼ 2.2 Hz,
H-5), 8.14 (s br, 1 H, H-2), 8.22 (d, 2 H, J ¼ 8.8 Hz, H-
30,50). 13C NMR d ¼ 21.0 (6-CH3), 117.9 (C-8), 120.6 (C-3),
123.5 (C-10), 124.1 (C-a,30,50), 125.5 (C-5), 126.9 (C-20,60),
129.3 (C-b), 135.1 (C-7), 135.7 (C-6), 144.1 (C-10), 146.8 (C-
40), 154.0 (C-9), 154.6 (C-2), 176.4 (ꢂC-4). EI-MS: m/z (rel.
int.) ¼ 308 [(M + 1)+, 27], 307 (M+ , 100), 306 [(M ꢀ 1)+,
48], 209 (8), 277 (11), 260 (19), 232 (5), 186 (5), 185 (59), 135
(26), 134 (30), 127 (9), 126 (10), 115 (8), 106 (16), 105 (10),
78 (20), 77 (15). Anal. calcd. for C18H13NO4 : C 70.35, H
4.26, N 4.56; found: C 70.35, H 4.43, N 4.51%.
=
=
ꢂ
35Cl, 12], 312 (M+
,
35Cl, 34), 311, [(M ꢀ 1)+, 35Cl, 41), 296
(5), 279 (4), 278 (11), 277 (22), 250 (4), 248 (7), 220 (10), 218
(14), 205 (10), 192 (22), 189 (10), 183 (19), 178 (15), 177 (59),
176 (14), 158 (16), 156 (44), 152 (17), 151 (89), 150 (62), 149
(35), 141 (41), 139 (100), 122 (25), 113 (16), 111 (44), 107
(46), 97 (16). Anal. calcd. for C18H13O3Cl: C 69.13, H 4.19;
found: C 69.14, H 4.19%.
(Z)-40-Chloro-5-methoxy-3-styrylchromone (4f). Mp 124–
ꢁ
=
126 C (recrystallised from ethanol). IR n ¼ 1644 (C O),
=
1609 (C C), 1571, 1475, 1435, 1376, 1355, 1295, 1267, 1188,
1141, 1087, 1010, 918, 818, 802, 774, 752, 684. 1H NMR
d ¼ 3.99 (s, 3 H, OCH3), 6.53 (dd, 1 H, J ¼ 12.1 and 1.0
Hz, H-a), 6.69 (d, 1 H, J ¼ 12.1 Hz, H-b), 6.82 (d, 1 H,
J ¼ 8.3 Hz, H-6), 6.95 (d, 1 H, J ¼ 8.3 Hz, H-8), 7.23 (s, 4
H, H-20,30,50,60), 7.53 (d, 1 H, J ¼ 1.0 Hz, H-2), 7.54 (t, 1 H,
J ¼ 8.3 Hz, H-7). 13C NMR d ¼ 56.4 (OCH3), 106.3 (C-6),
110.1 (C-8), 114.6 (C-10), 121.5 (C-a), 122.1 (C-3), 128.7 (C-
30,50), 129.9 (C-20,60), 130.9 (C-b), 132.8 (C-40), 133.7 (C-7),
135.2 (C-10), 152.0 (C-2), 158.1 (C-9), 160.0 (C-5), 176.7 (C-
(Z)-6-Methyl-40-nitro-3-styrylchromone (4h). Mp 179–
180 ꢁC (recrystallised from ethanol). IR n ¼ 3066, 1651
=
=
(C O), 1615 (C C), 1592, 1561, 1504, 1463, 1335, 1318,
1307, 1276, 1159, 1105, 969, 869, 857, 763, 745, 699. 1H
NMR d ¼ 2.47 (s, 3 H, 6-CH3), 6.71 (dd, 1 H, J ¼ 12.1 and
1.1 Hz, H-a), 6.83 (d, 1 H, J ¼ 12.1 Hz, H-b), 7.32 (d, 1 H,
J ¼ 8.7 Hz, H-8), 7.46 (d, 2 H, J ¼ 8.7 Hz, H-20,60), 7.50
(dd, 1 H, J ¼ 8.7 and 2.2 Hz, H-7), 7.68 (d, 1 H, J ¼ 1.1
Hz, H-2), 8.04 (d, 1 H, J ¼ 2.2 Hz, H-5), 8.13 (d, 2 H,
J ¼ 8.7 Hz, H-30,50). 13C NMR d ¼ 20.9 (6-CH3), 117.9 (C-
8), 120.5 (C-3), 123.6 (C-10), 123.9 (C-30,50), 124.1 (C-a),
125.3 (C-5), 129.4 (C-20,60), 130.6 (C-b), 135.2 (C-7), 135.6
(C-6), 143.6 (C-10), 146.6 (C-40), 154.0 (C-2), 154.4 (C-9),
176.7 (C-4). EI-MS: m/z (rel. int.) ¼ 308 [(M + 1)+, 23], 307
4). EI-MS: m/z (rel. int.) ¼ 315 [(M + 1)+, 37Cl, 4], 314
ꢂ
(M+
,
,
37Cl, 23), 313 [(M ꢀ 1)+, 37Cl, (M + 1)+, 35Cl, 17], 312
35Cl, 66), 311 [(M ꢀ 1)+, 35Cl, 16], 283 (10), 281 (8),
ꢂ
(M+
201 (10), 189 (6), 187 (5), 171 (7), 162 (9), 160 (12), 159
(100), 151 (8), 150 (13), 149 (7), 127 (25), 126 (11), 125 (30),
122 (13), 121 (14), 107 (30), 77 (7). Anal. calcd. for
C18H13O3Cl: C 69.13, H 4.19; found: C 69.13, H 4.21%.
(E)-40-Nitro-3-styrylchromone (3g). Mp 225–226 ꢁC (recrys-
=
=
tallised from ethanol). IR n ¼ 1643 (C O), 1613 (C C), 1594,
1561, 1509, 1461, 1342, 1318, 1276, 1210, 1183, 1108, 970, 869,
857, 770, 745, 700. 1H NMR (DMSO-d6) d ¼ 7.32 (d, 1 H,
J ¼ 16.3 Hz, H-a), 7.55 (ddd, 1 H, J ¼ 8.0, 6.9 and 1.0 Hz,
H-6), 7.72 (d, 1 H, J ¼ 8.2 Hz, H-8), 7.81 (d, 2 H, J ¼ 8.8
Hz, H-20,60), 7.85 (ddd, 1 H, J ¼ 8.2, 6.9 and 1.6 Hz, H-7),
7.94 (d, 1 H, J ¼ 16.3 Hz, H-b), 8.16 (dd, 1 H, J ¼ 8.0 and
1.6 Hz, H-5), 8.24 (d, 2 H, J ¼ 8.8 Hz, H-30,50), 8.77 (s, 1 H,
ꢂ
(M+ , 100), 306 [(M ꢀ 1)+, 49], 290 (7), 277 (8), 260 (18), 232
(5), 186 (5), 185 (52), 135 (17), 134 (22), 126 (5), 115 (5), 106
(10), 78 (14), 77 (13). Anal. calcd. for C18H13NO4 : C 70.35,
H 4.26, N 4.56; found: C 70.06, H 4.24, N 4.49%.
(E)-5-Methoxy-40-nitro-3-styrylchromone (3i). Mp 210–
ꢁ
=
211 C (recrystallised from ethanol). IR n ¼ 1655 (C O),
1596
New J. Chem., 2003, 27, 1592–1598

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=
1615 (C C), 1595, 1567, 1509, 1475, 1337, 1326, 1297, 1270,
(C-10), 129.8 (C-20,60), 132.3 (C-b), 133.5 (C-7), 154.0 (C-2),
1165, 1105, 1083, 976, 872, 808, 774, 746, 700. 1H NMR
d ¼ 4.02 (s, 3 H, OCH3), 6.85 (dd, 1 H, J ¼ 8.4 and 0.9 Hz,
H-6), 7.01 (dd, 1 H, J ¼ 16.3 and 0.5 Hz, H-a), 7.03 (dd, 1
H, J ¼ 8.4 and 0.9 Hz, H-8), 7.57 (t, 1 H, J ¼ 8.4 Hz, H-7),
7.60 (d, 2 H, J ¼ 8.8 Hz, H-20,60), 7.89 (d, 1 H, J ¼ 16.3 Hz,
H-b), 8.00 (s br, 1 H, H-2), 8.18 (d, 2 H, J ¼ 8.8 Hz, H-
30,50). 13C NMR d ¼ 56.4 (OCH3), 106.7 (C-6), 110.0 (C-8),
114.6 (C-10), 121.6 (C-3), 123.96 (C-a), 124.04 (C-30,50),
126.8 (C-20,60), 129.2 (C-b), 133.9 (C-7), 144.3 (C-10), 146.7
(C-40), 153.0 (C-2), 157.6 (C-9), 160.2 (C-5), 176.1 (Cꢂ-4). EI-
MS: m/z (rel. int.) ¼ 324 [(M + 1)+, 24], 323 (M+ , 100),
322, [(M ꢀ 1)+ 11], 307 (27), 306 (87), 293 (12), 277 (12), 276
(42), 247 (19), 201 (17), 171 (17), 159 (29), 150 (13), 122 (15),
107 (35), 92 (8). Anal. calcd. for C18H13NO5 : C 66.87, H
4.05, N 4.33; found: C 67.01, H 3.95, N 4.26%.
156.0 (C-9), 158.1 (C-40), 177.1 (C-4). EI-MS: m/z (rel.
ꢂ
int.) ¼ 293 [(M + 1)+, 58], 292 (M+ , 100), 291 [(M ꢀ 1)+,
49], 275 (7), 265 (12), 264 (30), 263 (89), 247 (18), 235 (20),
218 (5), 207 (11), 189 (5), 178 (14), 171 (16), 149 (14), 144
(16), 143 (8), 121 (23), 116 (7), 115 (36), 92 (10), 89 (8), 77
ꢂ
(6). EI-HRMS (C19H16O3 [M+ ]): calcd. 292.1099, found
292.1111.
(E)-40-Ethoxy-6-methyl-3-styrylchromone (3k). Mp 158-
159 ꢁC (recrystallised from ethanol). IR n ¼ 3065, 2978,
=
=
2932, 1641 (C O), 1615 (C C), 1562, 1509, 1485, 1478,
1431, 1390, 1350, 1274, 1244, 1178, 1156, 1114, 1046, 900,
856, 823, 810, 790. 1H NMR d ¼ 1.42 (t, 3 H, J ¼ 7.0 Hz,
CH3), 2.46 (s, 3 H, 6-CH3), 4.04 (q, 2 H, J ¼ 7.0 Hz, CH2),
6.85 (d, 1 H, J ¼ 16.4 Hz, H-a), 6.87 (d, 2 H, J ¼ 8.7 Hz,
H-30,50), 6.34 (d, 1 H, J ¼ 8.7 Hz, H-8), 7.44 (d, 2 H,
J ¼ 8.7 Hz, H-20,60), 7.45 (d, 1 H, J ¼ 8.7 Hz, H-7), 7.50 (d,
1 H, J ¼ 16.4 Hz, H-b), 8.05 (s, 1 H, H-2), 8.06 (s, 1 H, H-
5). 13C NMR d ¼ 14.8 (CH3), 20.9 (6-CH3), 63.4 (CH2),
114.5 (C-30,50), 116.7 (C-a), 117.7 (C-8), 121.8 (C-3), 123.6
(C-10), 125.4 (C-5), 127.8 (C-20,60), 130.0 (C-10), 130.8 (C-b),
134.6 (C-7), 135.0 (C-6), 152.3 (C-2), 154.1 (C-9), 158.7 (C-
40), 176.7 (C-4). EI-MS: m/z (rel. int.) ¼ 307 [(M + 1)+, 30],
(Z)-5-Methoxy-40-nitro-3-styrylchromone (4i). Mp 212–
ꢁ
=
214 C (recrystallised from ethanol). IR n ¼ 1642 (C O),
=
1606 (C C), 1594, 1567, 1509, 1476, 1439, 1336, 1293, 1267,
1
1192, 1104, 1076, 920, 876, 859, 803, 779, 716, 679. H NMR
d ¼ 4.00 (s, 3 H, OCH3), 6.69 (dd, 1 H, J ¼ 12.0 and 1.1
Hz, H-a), 6.78 (d, 1 H, J ¼ 12.0 Hz, H-b), 6.84 (dd, 1 H,
J ¼ 8.4 and 0.8 Hz, H-6), 6.95 (dd, 1 H, J ¼ 8.4 and 0.8 Hz,
H-8), 7.45 (d, 2 H, J ¼ 8.7 Hz, H-20,60), 7.49 (d, 1 H,
J ¼ 1.1 Hz, H-2), 7.56 (t, 1 H, J ¼ 8.4 Hz, H-7), 8.13 (d, 2
H, J ¼ 8.7 Hz, H-30,50). 13C NMR d ¼ 56.4 (OCH3), 106.6
(C-6), 110.1 (C-8), 114.6 (C-10), 121.8 (C-3), 123.9 (C-30,50),
124.5 (C-a), 129.5 (C-20,60), 130.1 (C-b), 133.9 (C-7), 143.7
(C-10), 146.6 (C-40), 152.0 (C-2), 158.1 (C-9), 160.0 (C-5),
176.4 (C-4). EI-MS: m/z (rel. int.) ¼ 324 [(M + 1)+, 21], 323
ꢂ
306 (M+ , 100), 305 [(M ꢀ 1)+, 22], 289 (7), 278 (23), 277
(69), 261 (13), 249 (12), 185 (13), 172 (8), 171 (7), 144 (19),
143 (10), 139 (12), 135 (19), 134 (7), 116 (6), 115 (29), 106
(6), 89 (10), 78 (10), 77 (12). Anal. calcd. for C20H18O3 : C
78.41, H 5.92; found: C 78.02, H 5.82%.
(Z)-40-Ethoxy-6-methyl-3-styrylchromone (4k). Mp 110–
112 ꢁC (recrystallised from ethanol). IR n ¼ 3065, 2978,
ꢂ
(M+ , 100), 322, [(M ꢀ 1)+ 10], 293 (11), 307 (19), 306 (85),
293 (11), 277 (10), 276 (35), 247 (17), 201 (14), 171 (14), 159
(22), 122 (14), 107 (34), 92 (7). Anal. calcd. for C18H13NO5 :
C 66.87, H 4.05, N 4.33; found: C 66.86, H 4.02, N 4.29%.
=
=
2923, 1643 (C O), 1617 and 1605 (C C), 1573, 1509, 1482,
1478, 1431, 1404, 1322, 1290, 1246, 1196, 1178, 1152, 1131,
1
1117, 1051, 907, 862, 830, 803, 773. H NMR d ¼ 1.40 (t, 3
H, J ¼ 7.0 Hz, CH3), 2.46 (s, 3 H, 6-CH3), 4.00 (q, 2 H,
J ¼ 7.0 Hz, CH2), 6.42 (dd, 1 H, J ¼ 12.1 and 1.1 Hz, H-a),
6.72 (d, 1 H, J ¼ 12.1 Hz, H-b), 6.78 (d, 2 H, J ¼ 8.7 Hz,
H-30,50), 7.22 (d, 2 H, J ¼ 8.7 Hz, H-20,60), 7.30 (d, 1 H,
J ¼ 8.5 Hz, H-8), 7.46 (dd, 1 H, J ¼ 8.5 and 1.9 Hz, H-7),
7.78 (d, 1 H, J ¼ 1.1 Hz, H-2), 8.06 (d, 1 H, J ¼ 1.9 Hz, H-
5). 13C NMR d ¼ 14.8 (CH3), 21.0 (6-CH3), 63.3 (CH2),
111.4 (C-30,50), 117.8 (C-8), 118.8 (C-a), 121.2 (C-3), 123.8
(C-10), 125.3 (C-5), 128.9 (C-10), 129.9 (C-20,60), 132.2 (C-b),
134.7 (C-7), 135.1 (C-6), 153.9 (C-2), 154.4 (C-9), 158.1 (C-
40), 177.2 (C-4). EI-MS: m/z (rel. int.) ¼ 307 [(M + 1)+, 30],
(E)-40-Ethoxy-3-styrylchromone (3j). Mp 129–130 ꢁC
(recrystallised from ethanol). IR n ¼ 2980, 2931, 1644
=
=
(C O), 1612 (C C), 1561, 1509, 1466, 1398, 1353, 1276,
1243, 1179, 1142, 1115, 1041, 977, 820, 758, 696. 1H NMR
d ¼ 1.44 (t, 3 H, J ¼ 7.0 Hz, CH3), 4.07 (q, 2 H, J ¼ 7.0
Hz, CH2), 6.87 (d, 1 H, J ¼ 16.4 Hz, H-a), 6.90 (d, 2 H,
J ¼ 8.7, Hz, H-30,50), 7.42 (dd, 1 H, J ¼ 7.8 and 1.4 Hz, H-
6), 7.47 (d, 2 H, J ¼ 8.7 Hz, H-20,60), 7.48 (d, 1 H, J ¼ 8.5
Hz, H-8), 7.56 (d, 1 H, J ¼ 16.4 Hz, H-b), 7.68 (ddd, 1 H,
J ¼ 8.5, 7.8 and 1.4 Hz, H-7), 8.11 (s, 1 H, H-2), 8.32 (dd, 1
H, J ¼ 7.8 and 1.4 Hz, H-5). 13C NMR d ¼ 14.8 (CH3),
63.4 (CH2), 114.6 (C-30,50), 116.6 (C-a), 118.0 (C-8), 122.1
(C-3), 124.0 (C-10), 125.1 (C-6), 126.2 (C-5), 127.8 (C-20,60),
130.0 (C-10), 131.2 (C-b), 133.4 (C-7), 152.4 (C-2), 155.8 (C-
9), 158.8 (C-40), 176.7 (C-4). EI-MS: m/z (rel. int.) ¼ 293
ꢂ
306 (M+ , 100), 305 [(M ꢀ 1)+, 15], 278 (20), 277 (68), 261
(10), 249 (12), 185 (9), 172 (8), 144 (17), 135 (16), 115 (26),
89 (6), 77 (6). Anal. calcd. for C20H18O3 : C 78.41, H 5.92,
found C 78.47, H 6.16%.
ꢂ
[(M + 1)+, 30], 292 (M+ , 100), 291 [(M ꢀ 1)+, 19], 275 (5),
264 (25), 263 (76), 247 (17), 235 (14), 219 (6), 218 (5), 207
(8), 205 (6), 189 (5), 178 (9), 172 (7), 171 (18), 144 (19), 143
(12), 132 (9), 121 (19), 116 (8), 115 (35), 92 (13), 89 (11), 77
(10). Anal. calcd. for C19H16O3Cl: C 78.06, H, 5.52; found:
C 77.68, H 5.51%.
(E)-40-Ethoxy-5-methoxy-3-styrylchromone (3l). Yellowish
=
=
oil. IR n ¼ 3012, 2937, 1643 (C O), 1604 (C C), 1568,
1511, 1475, 1431, 1392, 1299, 1268, 1249, 1174, 1114, 1074,
1043, 970, 921, 806, 732, 688. 1H NMR d ¼ 1.42 (t, 3 H,
J ¼ 7.0 Hz, CH3), 4.01 (s, 3 H, OCH3), 4.05 (q, 2 H, J ¼ 7.0
Hz, OCH2), 6.83 (d, 1 H, J ¼ 16.1 Hz, H-a), 6.84 (d, 1 H,
J ¼ 8.0 Hz, H-6), 6.88 (d, 2 H, J ¼ 8.7 Hz, H-30,50), 7.01 (d,
1 H, J ¼ 8.0 Hz, H-8), 7.43 (d, 2 H, J ¼ 8.7 Hz, H-20,60),
7.54 (t, 1 H, J ¼ 8.0 Hz, H-7), 7.55 (d, 1 H, J ¼ 16.1 Hz, H-
b), 7.94 (s, 1 H, H-2). 13C NMR: d ¼ 14.8 (CH3), 56.4
(OCH3), 63.5 (OCH2), 106.3 (C-6), 110.0 (C-8), 114.6 (C-
30,50), 114.7 (C-10), 116.8 (C-a), 123.1 (C-3), 127.8 (C-20,60),
130.2 (C-10), 130.8 (C-b), 133.4 (C-7), 150.6 (C-2), 157.9 (C-
9), 158.7 (C-40),ꢂ 160.3 (C-5), 176.4 (C-4). EI-MS: m/z (rel.
int.) ¼ 322 (M+ , 100), 305 (5), 293 (29), 278 (20), 250 (8),
201 (8), 159 (13), 151 (15), 144 (16), 135 (53), 121 (10), 115
(41),ꢂ 107 57), 89 (10), 77 (11), 63 (12). EI-HRMS (C20H18O4
[M+ ]): calcd. 322.1205, found 322.1212.
(Z)-40-Ethoxy-3-styrylchromone (4j). Yellowish oil. IR
=
=
n ¼ 2978, 2929, 1644 (C O), 1612 (C C), 1571, 1509, 1465,
1396, 1352, 1244, 1177, 1143, 1115, 1043, 976, 820, 758, 695.
1H NMR d ¼ 1.40 (t, 3 H, J ¼ 7.0 Hz, CH3), 4.00 (q, 2 H,
J ¼ 7.0 Hz, CH2), 6.42 (d, 1 H, J ¼ 12.1, Hz, H-a), 6.73 (d,
1 H, J ¼ 12.1 Hz, H-b), 6.79 (d, 2 H, J ¼ 8.7 Hz, H-30,50),
7.23 (d, 2 H, J ¼ 8.7 Hz, H-20,60), 7.4 (d, 1 H, J ¼ 8.0 Hz,
H-8), 7.41 (dd, 1 H, J ¼ 8.0 and 7.3 Hz, H-6), 7.66 (ddd, 1
H, J ¼ 8.0, 7.3 and 1.6 Hz, H-7), 7.80 (s, 1 H, 2-H), 8.28
(dd, 1 H, J ¼ 8.0 and 1.6 Hz, H-5). 13C NMR d ¼ 14.7
(CH3), 63.3 (CH2), 114.4 (C-30,50), 118.1 (C-8), 118.5 (C-a),
121.4 (C-3), 124.0 (C-10), 125.1 (C-6), 126.0 (C-5), 128.7
New J. Chem., 2003, 27, 1592–1598
1597

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Gill and M. S. Shingare, Indian J. Heterocycl. Chem., 2001, 10,
233–234.
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Recueil, 1997, 2065–2068.
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(a) P. J. Cremins, S. T. Saengchantara and T. W. Wallace,
Tetrahedron, 1987, 43, 3075–3082; (b) S. T. Saengchantara and
T. W. Wallace, Tetrahedron, 1990, 46, 3029–3036; (c) S. J. Coutts
and T. W. Wallace, Tetrahedron, 1994, 50, 11755–11780; (d )
C. K. Ghosh and C. Ghosh, Indian J. Chem., 1997, 36B, 968–980;
(e) R. P. Hsung, J. Org. Chem., 1997, 62, 7904–7905; ( f ) K. A.
Granum, G. Merkel, J. A. Mulder, S. A. Debbins and R. P.
Hsung, Tetrahedron Lett., 1998, 39, 9597–9600; (g) R. P. Hsung,
Heterocycles, 1998, 48, 421–425; (h) S. J. Degen, K. L. Mueller,
H. C. Shen, J. A. Mulder, G. M. Golding, L. Wei, C. A. Zificsak,
A. Neeno-Eckwall and R. P. Hsung, Bioorg. Med. Chem. Lett.,
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L. R. Zehnder, F. Park, M. Kim and T. -T. Tran, J. Org. Chem.,
1999, 64, 8736–8740.
(Z)-40-Ethoxy-5-methoxy-3-styrylchromone (4l). Mp 107–
108 ꢁC (recrystallised from ethanol). IR n ¼ 3093, 2971,
2
3
=
=
2925, 1644 (C O), 1602 (C C), 1567, 1510, 1475, 1431,
1373, 1353, 1290, 1268, 1180, 1141, 1076, 1045, 852, 815,
1
773, 686. H NMR d ¼ 1.40 (t, 3 H, J ¼ 7.0 Hz, CH3), 3.99
(s, 3 H, OCH3), 4.00 (q, 2 H, J ¼ 7.0 Hz, OCH2), 6.40 (dd,
1 H, J ¼ 12.1 and 1.2 Hz, H-a), 6.68 (d, 1 H, J ¼ 12.1 Hz,
H-b), 6.79 (d, 2 H, J ¼ 8.7 Hz, H-30,50), 6.80 (dd, 1 H,
J ¼ 8.3 and 0.8 Hz, H-6), 6.94 (dd, 1 H, J ¼ 8.3 and 0.8 Hz,
H-8), 7.22 (d, 2 H, J ¼ 8.7 Hz, H-20,60), 7.52 (t, 1 H, J ¼ 8.3
Hz, H-7), 7.62 (d, 1 H, J ¼ 1.2 Hz, H-2). 13C NMR:
d ¼ 14.7 (CH3), 56.3 (OCH3), 63.3 (OCH2), 106.2 (C-6),
110.1 (C-8), 114.4 (C-30,50), 114.7 (C-10), 119.1 (C-a), 122.5
(C-3), 128.9 (C-10), 129.8 (C-20,60), 131.7 (C-b), 133.5 (C-7),
152.0 (C-2), 158.0 and 158.1 (C-9 and C-40), 159.9 (C-5), 176.8
4
5
6
7
8
9
ꢂ
(C-4). EI-MS: m/z (rel. int.) ¼ 322 (M+ , 100), 321 (20), 305 (7),
293 (26), 278 (19), 263 (11), 250 (7), 201 (8), 172 (8), 160
(12), 151 (13), 144 (15), 135 (49), 121 (10), 115 (32), 107 (45),
89 (7), 77 (7), 65 (6). Anal. calcd. for C20H18O4 : C 74.52, H
5.63; found: C 74.32, H 5.86%.
Acknowledgements
Thanks are due to the University of Aveiro, ‘‘Fundac¸a˜o para a
ˆ
Ciencia e Tecnologia’’ and FEDER for funding the Organic
Chemistry Research Unit and the project POCTI/QUI/
38394/2001. A. Sandulache also thanks FCT for a PhD grant
(BD/19670/99) and the Dunarea de Jos University, Galati,
Romania for her leave of absence.
10 (a) O. I. Kolodiazhnyi, in Phosphorous Ylides–Chemistry and
Application in Organic Synthesis, Wiley-VCH, Weinheim, 1999,
p. 359–538; (b) B. E. Maryanoff, A. B. Reitz, M. S. Mutter,
R. R. Inners, H. R. Almond, Jr., R. R. Whittle and R. A. Olofson,
J. Am. Chem. Soc., 1986, 108, 7664–7678; (c) B. E. Maryanoff and
A. B. Reitz, Chem. Rev., 1989, 89, 863–927.
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11 In the case of 40-nitro-3-styrylchromones 3g and 4g the resonances
of H-2 appear at higher frequencies (d ¼ 8.77 and 8.20 ppm).
These values were not compared with the others 3-styrylchro-
mones 3a–f,h–l and 4a–f,h–l, since the NMR spectra of these
compounds were recorded in a different solvent (DMSO-d6) due
to solubility problems.
12 A. Sandulache, A. M. S. Silva and J. A. S. Cavaleiro, Tetrahedron,
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1598
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