Synthesis of flavonoid-type compounds from methyl dehydroabietates

Article abstract of DOI:10.1007/s00706-008-0889-1

The synthesis of new flavone-type compounds bearing several chiral centres, 12- and 14-(2′-chromonyl)dehydroabietates, are reported. This synthesis started from the aldol condensation of methyl 12- and 14-formyldehydroabietates with 2′-hydroxyacetophenones in order to prepare the corresponding chalcone-type compounds, which were then transformed in the expected flavone-type compounds by cyclodehydrogenation with DMSO and a catalytic amount of iodine. All compounds were exhaustively characterised by NMR and MS techniques.

Full text of DOI:10.1007/s00706-008-0889-1

Monatsh Chem 139, 1119–1126 (2008)
DOI 10.1007/s00706-008-0889-1
Printed in The Netherlands
Synthesis of flavonoid-type compounds from methyl dehydroabietates
ꢀ
´
Silvia M. C. S. Monteiro , Armando J. D. Silvestre, Artur M. S. Silva, Jose A. S. Cavaleiro
Chemistry Department, University of Aveiro, Aveiro, Portugal
Received 20 December 2007; Accepted 9 January 2008; Published online 18 February 2008
# Springer-Verlag 2008
Abstract The synthesis of new flavone-type com-
pounds bearing several chiral centres, 12- and 14-
(20-chromonyl)dehydroabietates, are reported. This
synthesis started from the aldol condensation of
methyl 12- and 14-formyldehydroabietates with 20-
hydroxyacetophenones in order to prepare the corre-
sponding chalcone-type compounds, which were then
transformed in the expected flavone-type compounds
by cyclodehydrogenation with DMSO and a catalytic
amount of iodine. All compounds were exhaustively
characterised by NMR and MS techniques.
pounds either synthesized or isolated from natural
sources have shown promising biological activities
[2–4]. Reactions of the aromatic moiety involving
various aromatic substitution reactions are used in
the synthesis of natural and bioactive products [5–
8]. The dihydroabietic acid, and similar compounds,
can also be chemically transformed to obtain new
compounds with other potencialities [9].
20-Hydroxychalcones and flavones are important
groups of heterocyclic polyphenolic compounds
widely distributed in the plant kingdom, where they
participate in several vital functions [10]. Moreover
promising pharmaceutical, biocidal, and antioxidant
activities have been found for some of these natural
compounds and for certain synthetic analogues [11].
The industrial significance of such properties, the
search of new and more potent biological active deriv-
atives, the potential synergetic effect with dehydroa-
bietates and our interests on the synthesis of more
valuable compounds from dehydroabietic acid [12]
and on the synthesis of some flavonoid derivatives
[13], led us to study the synthesis of novel flavonoid-
dehydroabietates dyads. The stereochemical features
of the new products might bring a contribution to
potential biological properties.
Keywords Chromones; Chalcones; Dehydroabietate deriva-
tives; NMR; MS.
Introduction
Dehydroabietic acid can be easily obtained by cata-
lytic dehydrogenation of abietic-type resin acids,
which are very abundant in pine resin [1]. Among
resin acids, those of abietic acid-type are the most
abundant; they are also the most versatile for chemi-
cal synthesis due to the presence of the conjugated
double bond system. Dehydroabietic acid has been
considered as an interesting starting material for the
synthesis of new and more valuable compounds, es-
pecially with significant biological properties. It is
well-known that many oxygenated diterpenic com-
Results and Discussion
ꢀ
Institute of Leiria, 2411–901 Leiria, Portugal.
Synthesis
Present address: Environment Department, Polytechnic
Our synthesis study started with the formylation of
1. Vielsmeier reaction proved to be unsuccessful to
prepare the expected formyl derivative 2. The for-
´
Correspondence: Jose A. S. Cavaleiro, Chemistry Depart-
ment, University of Aveiro, 3810-193 Aveiro, Portugal.
E-mail: jcavaleiro@ua.pt

1120
S. M. C. S. Monteiro et al.
Scheme 1
mylation of 1 with ꢀ,ꢀ-dichloromethyl methyl ether
in the presence of aluminium(III) chloride was at-
tempted according to literature data, using dichloro-
methane as solvent [14]; compound 2 was then
obtained in poor yields (ꢁ15%). However, when the
reaction was carried out in nitrobenzene, a solvent
commonly used in Friedel-Crafts reactions, com-
pound 2 was isolated in 50% yield, and also methyl
14-formyldehydroabietate 3 was isolated in lower
yields (ꢁ22%) (Scheme 1).
lated (8%) from the reaction media after 15 min; and
after 120 min a complete debenzylation took place
yielding compound 7d in 10% yield.
Structural characterisation
The most important features of the spectra of 2 are
the proton and carbon resonances of the formyl group
(ꢁH ¼ 10.27 and ꢁC ¼ 192.2). In the case of 3, these
signals appear at ꢁH 10.63 ppm and ꢁC 195.7 ppm.
The two doublets at ꢁH 7.24 and 7.42 ppm, with J
values characteristic of ortho protons (J ¼ 8.4 Hz) in
the 1H NMR spectrum of 3 instead of two singlets in
that of 2, confirm that positions 11 and 12 are not
functionalized and therefore the presence of a 14-
20-Hydroxychalcones 4a–4c and 6a–6c were
synthesised by base-catalysed aldol condensations
of the adequate 20-hydroxyacetophenones and the
benzaldehyde-type compounds 2, 3 (Scheme 2). In
general, it was observed that even with a longer re-
action time, chalcones 6a–6c were obtained in lower
yields (42–75%) than chalcones 4a–4c (55–85%),
due to the higher steric hindrance of position 14.
The oxidative cyclization of 20-hydroxychalcones
4a–4c and 6a–6c into flavones 5a–5d and 7a–7d
was carried out in DMSO in the presence of a cata-
lytic amount of iodine (Scheme 2) [13]. The forma-
tion of flavones 5d and 7d can be explained by the
oxidative cyclization of the corresponding chalcones
4c and 6c followed by cleavage of the benzylic
group of compounds 5c and 7c, as it has been re-
ported in the synthesis of 5-hydroxychromones [15].
The yields of benzylated and debenzylated products
depend mainly on the reaction time: for compounds
5c=5d it was found that, after 15 min, 5c was formed
in 90% yield and 5d in only 5%; on the other hand,
after 120 min, only 5d was isolated in 87% yield.
Finally, it was also found that the cyclization of
chalcones 6a–6c yielded more complex mixtures and
lower yields than those found for chalcones 4a–4c;
in the case of chalcone 6b the corresponding cycli-
zation product was never isolated. When compared
with compounds 4a–4c this difference in reactivity
should again be due to the higher hindrance of posi-
tion 14. In the case of compound 7c, it can be iso-
1
formyl group. H and 13C resonances of the methyl
protons of the isopropyl group of 3 appear at differ-
ent chemical shift values, as it was already described
for 12-substituted derivatives [12], due to the steric
hindrance caused by the 14-substituent.
1
In the H NMR spectra of chalcones 4a–4c and
6a–6c the ꢂ-proton resonances appear at higher fre-
quency values (ꢁH 7.85–8.35 ppm) than those of ꢀ-
protons (ꢁH 7.18–7.74 ppm), which is due to the
deshielding mesomeric effect of the carbonyl group.
The coupling constants JHꢀ-Hꢂ 15–16 Hz indicate
a trans configuration for these vinylic systems. The
existence of strong hydrogen bonds involving the
carbonyl groups and the 20-hydroxyl proton was con-
firmed by the presence of proton resonances at ꢁH
1
12.78–13.24 ppm. In the H NMR spectrum of 4c,
H-1eq and H-20 resonances were shifted to lower
frequency values relatively to other chalcones 4a,
4b, due to the anisotropic shielding effect of the
phenyl ring of the 20-benzyloxy group. This phenom-
enon was confirmed by the close proximities of H-ꢂ
to H-15, H-ꢀ to H-11, and H-20 to H-200,600 (phenyl
ring of the benzyloxy group), infered from the cross
peaks observed in its NOESY spectrum. These NOE
effects allowed us to assign the structure of com-

Synthesis of flavonoid-type compounds
1121
Scheme 2
pounds 4a–4c as depicted in Scheme 2 and to sug-
gest the absence of free rotation about the bond C-
ꢂ–C-12. In the NOESY spectrum of compound 6c
NOE cross peaks between the resonances of H-ꢀ and
H-ꢂ and those of H-7 and H-15 indicate that there is
a free rotation around the bond C-ꢂ–C-14.
values of H-7, H-15, H-ꢀ, H-ꢂ, and 20-OH reso-
nances (ꢁH ¼ 2.91–2.94, 3.36, 7.50–7.74, 8.22–
8.35, and 12.92–13.24 ppm) relatively to those of
4a–4c (ꢁH ¼ 2.67–2.77, 3.15–3.25, 7.18–7.39,
7.85–8.03, and 12.78–13.14 ppm). Another effect
of the non-coplanarity is the higher frequency values
of the C-ꢂ resonance of compounds 6a–6c relatively
to those of 4a–4c (ꢁC ¼ 142.6–145.6 and 141.0–
143.8 ppm), due to the lack of conjugation between
the ꢀ,ꢂ-unsaturated system and the B ring.
The assignment of H-30 and H-50 resonances
of compounds 4b, 4c and 6b, 6c was performed
by using HETCOR and one-dimensional selective
INEPT. Upon irradiation of 20-OH resonance (ꢁOH
¼
12.94–13.24 ppm), signal enhancements were ob-
served at ꢁC ¼ 118.8–112.6, 164.4–165.0 and 101.5–
110.9 ppm, which were therefore assigned to C-10,
C-20, and C-30. After the assignment of C-30, based
on the HETCOR spectra, it was possible to assign
H-30 ressonances to the double doublet at ꢁH ¼ 6.62–
6.64 ppm and therefore confirmed the assignment of
H-50 to the double doublet at ꢁH 6.40–6.50 ppm.
It is known that the resonances of some protons of
20-hydroxychalcones are quite sensitive to the B ring
substituents [13], which in the present case corre-
sponds to the aromatic ring of the methyl dehydroa-
bietate moiety. Compounds 6a–6c have two alkyl
substituents in the ortho positions relatively to the
ꢀ,ꢂ-unsaturated system (while compounds 4a–4c
have only one), leading to a non-coplanarity of the
B ring with the other part of the 20-hydroxychalcone
moiety. The referred absence of coplanarity in chal-
cone 6a–6c is responsible for the higher frequency
The main feature in the NMR spectra of flavones
5a–5d and 7a–7d are the resonances of the H-30
and C-3, which appear at ꢁ 6.24–6.45 and 110.2–
1
115.4 ppm. In the H and 13C NMR spectra of fla-
vones 7a–7d, some signals appeared in a duplicated
form, suggesting the presence of two conformations
for each compound, differing in the orientation of
the chromonyl moiety relatively to the rest of the
molecule. The NOE cross peaks of H-30 with H-7
signals of one form and also of H-30 with H-16 and
H-17 signals of the other form, led us to conclude
that H-30 is close to H-7 in the former and close to
the isopropyl group in the latter. Attempts to sepa-
rate the two forms of each compound 7a–7d by
preparative TLC were not successful. However the
separation of the two forms of flavone 7d by HPLC
revealed the presence of two chromatographic peaks
which were collected in separate fractions. The pu-
rity of each fraction was confirmed immediately after

1122
S. M. C. S. Monteiro et al.
Fig. 1 Connectivities found in the HMBC spectrum of flavone-type compounds 5a and 5d
the HPLC isolation and solvent evaporation and
revealed that each fraction becomes again a mixture.
This observation confirms that each compounds 7a–
7d exists as a mixture of two conformers that can be
easily interconverted. Additionally it was observed
that the referred duplication of proton resonances at
room temperature disappeared at 57ꢂC, thus mean-
ing that at this temperature the energy barrier be-
tween the two conformers can be easily overcome.
The unequivocal assignement of carbon resonan-
ces of flavone-type compounds 5a–5d and 7a–7d
were based on HETCOR and HMBC spectra; being
the main connectivities found in the HMBC spec-
trum of 5a and 5d shown in Fig. 1 as representatives.
The analysis of the electronic impact mass spectra
of the synthesised compounds must take into consid-
eration the characteristic fragmentations of methyl
dehydroabietate [16] and of the substituents being
present at positions 12 or 14. In the diterpenic moie-
ty of the molecule, the most relevant fragmentations
correspond to the loss of 10–CH3 [M-15]þ, followed
ing from demethylation=debenzylation [M–Bz]þ
=
ꢃ
[M–Me]þ followed by the loss of CO were observed.
ꢃ
For compounds 4c and 6c the fragment at m=z 91,
characteristic for a tropylium ion is also detected.
Finally, compounds 5a–5d and 7a–7d show very
intense molecular ions (ꢁ100%) and the charac-
teristic fragmentation of flavones resulting from the
retro-Diels-Alder cleavage of the chromonyl moieties.
Conclusion
The synthesis of chalcone derivatives of methyl 12-
and 14-formyldehydroabietates was achieved in good
yields. The corresponding flavone-type structures
were obtained in good yields in the case of 12-sub-
stituted derivatives 5, whereas in the case of 14-
substituted derivatives 7 only moderate yields were
obtained, probably due to the high steric hindrance
of this position.
Experimental
by the loss of HCO CH [M-75]þ , or the direct loss
ꢃ
Melting points were determined in a Reichert Thermovar ap-
paratus fitted with a microscope. NMR spectra were recorded
on a Bruker AMX 300 spectrometer (300.13MHz for 1H and
75.47 MHz 13C), with CDCl3 as solvent. Chemical shifts (ꢁ)
are reported in ppm values and coupling constants (J) in Hz.
2
3
of CO2CH3 [M-59]þ, and the loss of isopropyl group
[M-43]þ.
Apart from the fragmentation of the diterpenic
moiety of the molecule, the mass spectra of the com-
pounds 4a–4c and 6a–6c also show the character-
istic fragmentations of chalcone type compounds,
involving mainly the cleavage of C–C bonds around
the carbonyl group. Thermal isomerization of chal-
cones into flavanones sometimes occurs in the ioni-
sation chamber, then a series of ions derived from
the isomeric flavanones in spectra of chalcones can
be observed [17]. This situation was observed for
chalcones 4a, 4b and 6a, 6b. In addition, for com-
1
The internal reference was TMS. H assignments were made
using NOESY spectra (mixing time 800 ms), while 13C assign-
ments were made using 1D selective INEPT [18] (long-range
C=H coupling constants optimised to 7 Hz) and 2D HETCOR
and HMBC (the low-pass J-filter portion of the experiment
was optimised for an average of one-bond heteronuclear
coupling of 145 Hz. The delay for evolution of long-range
couplings was optimised for 7 Hz) experiments. Mass spectra
(EI, 70 eV) were measured on a VG Autospec Q and M
mass spectrometer (HRMS data were in good agreement
(ꢄ5 ppm) with the calculated values). Elemental analyses
were obtained with a Carlo Erba 1108 CHNS analyser and
were in good agreement (ꢄ0.4%) with the calculated values.
Preparative thin layer chromatography was carried out with
Riedel silica gel 60 DGF254, and column chromatography
using Merk silica gel 60, 70–230 mesh. All chemicals and
pound 6a, a [Mþ2]þ fragment, probably arising
ꢃ
from the reduction of the ꢀ,ꢂ-unsaturation in the
ionisation chamber, was also observed. In compounds
4b, 4c and 6b, 6c the characteristic fragments result-

Synthesis of flavonoid-type compounds
1123
General method for the synthesis of 20-hydroxychalcones 4a–4c
Dry sodium hydride (7mg, 0.31mmol) was added to a dried
solution of the appropriate acetophenone (0.15 mmol) in
10cm3 THF under nitrogen. After stirring for 5 min, 50 mg
methyl 12-formyldehydroabietate (2) (0.15 mmol) were added
and the reaction mixture was stirred for 20h. After this period,
the mixture was poured into 20cm3 H2O, 30g ice, and com-
mercial HCl (pH of resulting mixture adjusted to 2). The ob-
tained mixture was extracted with CHCl3 (3ꢅ30cm3), and the
combined organic layers were dried with anhydrous sodium
sulfate, and the solvent was evaporated to dryness. The residue
was taken in 2 cm3 CH2Cl2 and purified by preparative thin-
layer chromatography using dichloromethane as eluent. With
20-hydroxyacetophenone as starting material 4a was ob-
tained (38 mg, 55%); 20-hydroxy-60-methoxyacetophenone
gave 4b (59 mg, 80%), and 20-benzyloxy-60-hydroxyacetophe-
none gave 4c (72 mg, 85%).
solvents used were obtained from commercial sources and
used as received or dried using standard procedures. High
performance liquid chromatography was performed on a
GILSON equipped with a Spherisorb – S5W column, a UV-
Vis detector GILSON 118 set at l ¼ 298 nm, and a Shimadzu
C-R1B integrator. A mixture of cyclohexane:ethyl acetate
(94:6) was used as eluent (1cm3=min). Methyl dehydroabie-
tate (1) was obtained by catalytic dehydrogenation of methyl-
ated resin according to Ref. [1].
Formylation of methyl dehydroabietate (1)
AlCl3 (1.1g, 8.0 mmol) and 190 mm3 CHCl2OCH3 (2.1 mmol)
were added to a solution of 500 mg methyl dehydroabietate (1)
(1.6mmol) in 10 cm3 nitrobenzene, at room temperature. After
stirring for 2.5 h, the solution was poured into a 20 cm3 satu-
rated solution of NaHCO3. This mixture was extracted with
CHCl3 (3ꢅ100 cm3), the combined organic layers were dried
over anhydrous sodium sulfate, and the solvent was evapo-
rated to dryness. The residue was taken in 5 cm3 CH2Cl2
and purified by preparative thin-layer chromatography using
CH2Cl2 as eluent. After several elutions two spots were iso-
lated; the one with higher Rf value was identified as compound
2 (274mg, 50%) and that with lower Rf value as compound 3
(120 mg, 22%).
Methyl 12-[2-(2-hydroxybenzoyl)vinyl]dehydroabietate
(4a, C30H36O4)
Yellow oil; 1H NMR: ꢁ ¼ 1.24, 1.27 (2d, J ¼ 6.8 Hz, H-
16, H-17), 1.26 (s, H-20), 1.30 (s, H-19), 1.42–1.90 (m, H-
1,2,3,6), 2.25 (dd, J ¼ 2.1, 12.5 Hz, H-5), 2.42 (d, J ¼
11.4Hz, H-1), 2.91–2.96 (m, H-7), 3.36 (heptet, J ¼ 6.8 Hz,
H-15), 3.68 (s, 18-OCH3), 6.96 (dt, J ¼ 1.1, 7.6 and 7.7Hz,
H-50), 7.02 (s, H-14), 7.03 (d, J ¼ 8.0 Hz, H-30), 7.50
(dd, J ¼ 7.6, 8.0 Hz, H-40), 7.50 (d, J ¼ 15.2 Hz, H-ꢀ), 7.56
(s, H-11), 7.94 (dd, J ¼ 1.4, 7.7 Hz, H-60), 8.35 (d, J ¼
15.2 Hz, H-ꢂ), 12.92 (s, 20-OH) ppm; 13C NMR: ꢁ ¼ 16.5
(C-19), 18.4 (C-2), 21.4 (C-6), 23.6, 23.9 (C-16, C-17),
25.1 (C-20), 28.8 (C-15), 30 (C-7), 36.6 (C-3), 37 (C-10),
37.9 (C-1), 44.6 (C-5), 47.6 (C-4), 52 (18-OCH3), 118.6
(C-30), 118.8 (C-50), 120.1 (C-ꢀ), 120.3 (C-10), 122.6
(C-11), 126.3 (C-14), 129.6 (C-60), 130.2 (C-12), 136.2
(C-40), 138.8 (C-8), 143.8 (C-ꢂ), 145.9 (C-13), 147.4
(C-9), 163.6 (C-20), 178.9 (C-18), 193.8 (C¼O) ppm;
Methyl 12-formyldehydroabietate (2, C22H30O3)
Yellow oil; 1H NMR: ꢁ ¼ 1.22 (s, H-20), 1.26, 1.28
(d, J ¼ 6.6Hz, H-16, H-17), 1.29 (s, H-19), 1.61–1.79 (m,
H-1,2,3,6), 2.20 (dd, J ¼ 2.2, 12.8Hz, H-5), 2.41 (d, J ¼
11.7Hz, H-1), 2.92–2.975 (m, H-7), 3.68 (s, 18-OCH3), 3.88
(heptet, J ¼ 6.6 Hz, H-15), 7.08 (s, H-14), 7.71 (s, H-11), 10.27
(s, 12-CHO) ppm; 13C NMR: ꢁ ¼ 16.5 (C-19), 18.4 (C-2), 21.3
(C-6), 23.7, 24.0 (C-16, C-17), 25.0 (C-20), 27.2 (C-15), 30.3
(C-7), 36.6 (C-3), 36.9 (C-10), 37.8 (C-1), 44.6 (C-5), 47.5
(C-4), 52.0 (18-OCH3), 126.8 (C-11), 128.1 (C-14), 131.0
(C-12), 142.4 (C-8), 147.6 (C-13), 148.1 (C-9), 178.9
(C-18), 192.2 (12-CHO) ppm; MS (EI): m=z (%) ¼ 342 (53)
MS (EI): m=z (%) ¼ 460 (9) [M]þ , 417 (100), 385 (11),
ꢃ
[M]þ , 325 (22), 297 (14), 283 (73), 267 (100), 255 (12), 217
121 (24).
ꢃ
(10), 213 (12), 201 (16), 197 (11), 181 (14), 169 (11), 155
(13), 143 (11), 141 (14), 129 (14), 128 (13), 55 (12).
Methyl 12-[2-(2-hydroxy-6-methoxybenzoyl)vinyl]dehydro-
abietate (4b, C31H38O5)
Yellow oil; 1H NMR: ꢁ ¼ 1.24, 1.27 (2d, J ¼ 6.8 Hz, H-16, H-
17), 1.25 (s, H-20), 1.29 (s, H-19), 1.42–1.93 (m, H-1,2,3,6),
2.25 (dd, J ¼ 2.2, 12.5 Hz, H-5), 2.36 (d, J ¼ 11.6Hz, H-1),
2.90-2095 (m, H-7), 3.36 (heptet, J ¼ 6.8Hz, H-15), 3.67 (s,
18-OCH3), 3.94 (s, 60-OCH3), 6.44 (dd, J ¼ 0.7, 8.3Hz, H-50),
6.62 (dd, J ¼ 0.7, 8.3 Hz, H-30), 7.00 (s, H-14), 7.36 (t,
J ¼ 8.3Hz, H-40), 7.54 (s, H-11), 7.74 (d, J ¼ 15.3Hz, H-ꢀ),
8.22 (d, J ¼ 15.3Hz, H-ꢂ), 13.24 (s, 20-OH) ppm; 13C NMR:
ꢁ ¼ 16.5 (C-19), 18.5 (C-2), 21.5 (C-6), 23.5, 23.9 (C-16, C-
17), 25.2 (C-20), 26.7 (C-15), 29.9 (C-7), 36.5 (C-3), 36.9
(C-10), 37.9 (C-1), 44.6 (C-5), 47.5 (C-4), 51.9 (18-OCH3),
55.8 (60-OCH3), 101.5 (C-30), 110.9 (C-50), 112 (C-10),
122.9 (C-11), 126.1 (C-14), 128.1 (C-ꢀ), 130.9 (C-12),
135.7 (C-40), 138 (C-8), 141.3 (C-ꢂ), 145.6 (C-13), 147.1
(C-9), 160.9 (C-2), 164.8 (C-20), 178.9 (C-18), 194.5
Methyl 14-formyldehydroabietate (3, C22H30O3)
Yellow oil; 1H NMR: ꢁ ¼ 1.23 (s, H-20), 1.23, 1.28 (2d,
J ¼ 6.8 Hz, H-16, H-17), 1.27 (s, 19), 1.45–1.86 (m, H-
1,2,3,6), 2.21 (dd, J ¼ 2.0, 12.6Hz, H-5), 2.30 (d, J ¼
11.4Hz, H-1), 3.08–3.14 (m, H-7), 3.53 (heptet, J ¼ 6.8 Hz,
H-15), 3.67 (s, 18-OCH3), 7.24 (d, J ¼ 8.4Hz, H-12), 7.42 (d,
J ¼ 8.4 Hz, H-11), 10.63 (s, 14-CHO) ppm; 13C NMR:
ꢁ ¼ 16.4 (C-19), 18.5 (C-2), 21.4 (C-6), 23.9, 24.2 (C-16,
C-17), 25.0 (C-20), 28.1 (C-15), 28.2 (C-7), 36.3 (C-3),
37.3 (C-10), 38.2 (C-1), 43.9 (C-5), 47.4 (C-4), 52.0 (18-
OCH3), 123.7 (C-12), 129.1 (C-11), 132.6 (C-14), 136.0
(C-8), 147.8 (C-9,13), 178.9 (C-18), 195.7 (14-CHO) ppm;
MS (EI): m=z (%) ¼ 342 (95) [M]þ , 282 (13), 267 (100),
ꢃ
249 (12), 239 (17), 227 (11), 214 (11), 213 (23), 211 (13),
201 (18), 199 (11), 197 (10), 195 (19), 183 (16), 181 (12),
169 (18), 167 (11), 165 (13), 155 (16), 153 (11), 143 (12),
141 (18), 129 (15), 128 (16), 115 (12), 59 (12), 55 (14).
(C¼O) ppm; MS (EI): m=z (%) ¼ 490 (7) [M]þ , 447
ꢃ
(100 177 (13), 151 (48).

1124
S. M. C. S. Monteiro et al.
m=z (%) ¼ 462 (7) [M þ 2]þ , 444 (74), 419 (100), 385 (34),
ꢃ
Methyl 12-[2-(6-benzyloxy-2-hydroxybenzoyl)vinyl]dehydro-
abietate (4c, C37H42O5)
367 (41), 338 (10), 263 (12), 121 (99), 83 (11).
Yellow oil; 1H NMR: ꢁ ¼ 1.04 (s, H-20), 1.22, 1.25
(2d, J ¼ 6.8 Hz, H-16, H-17), 1.24 (s, H-19), 1.39–1.85 (m,
H-1,2,3,6), 1.90 (d, J ¼ 12.7 Hz, H-1), 2.14 (dd, J ¼ 2.2,
12.5Hz, H-5), 2.89–2.93 (m, H-7), 3.36 (heptet, J ¼ 6.8 Hz,
H-15), 3.68 (s, 18-OCH3), 5.20 (s, 60-OCH2Ph), 6.50 (d,
J ¼ 8.0 Hz, H-50), 6.64 (d, J ¼ 8.3Hz, H-30), 6.98 (s, H-14),
7.13 (t, J ¼ 7.2Hz, H-300, 500), 7.22 (t, J ¼ 7.3 Hz, H-400), 7.31
(s, H-11), 7.31–7.37 (m, H-200,600, H-40), 7.74 (d, J ¼ 15.3 Hz,
H-ꢀ), 8.22 (d, J ¼ 15.3Hz, H-ꢂ), 12.94 (s, 20-OH) ppm; 13C
NMR: ꢁ ¼ 16.4 (C-19), 18.4 (C-2), 21.4 (C-6), 23.5, 24.0
(C-16, C-17), 25 (C-20), 28.6 (C-15), 29.9 (C-7), 36.5
(C-3), 36.7 (C-10), 37.3 (C-1), 44.5 (C-5), 47.5 (C-4), 51.9
(18-OCH3), 70.8 (60-OCH2Ph), 103 (C-30), 111.1 (C-50), 112.6
(C-10), 122.7 (C-11), 125.9 (C-14), 126.5 (C-200, 600), 126.5 (C-
400), 128 (C-300, 500), 128.5 (C-ꢀ), 130.6 (C-12), 135.6 (C-40),
136 (C-100), 137.9 (C-8), 141.0 (C-ꢂ), 145.6 (C-13), 147.2 (C-
9), 159.9 (C-60), 164.4 (C-20), 179 (C-18), 194.6 (C¼O) ppm;
Methyl 14-[2-(2-hydroxy-6-methoxybenzoyl)vinyl]dehydro-
abietate (6b, C31H38O5)
Yellow oil; 1H NMR: ꢁ ¼ 1.19, 1.23 (d, J ¼ 6.8 Hz, H-
16, H-17), 1.24 (s, H-20), 1.27 (s, H-19), 1.40–1.87 (m,
H-1,2,3,6), 2.23 (dd, J ¼ 2.0, 12.5 Hz, H-5), 2.33 (d, J ¼
11.7Hz, H-1), 2.75–2.80 (m, H-7), 3.25 (heptet, J ¼ 6.8 Hz,
H-15), 3.65 (s, 18-OCH3), 3.86 (s, 60-OCH3), 6.40 (dd,
J ¼ 0.7, 8.3 Hz, H-50), 6.63 (dd, J ¼ 0.7, 8.3 Hz, 30), 7.18 (d,
J ¼ 8.5Hz, H-12), 7.27 (d, J ¼ 8.5 Hz, H-11), 7.31 (d, J ¼
15.9Hz, H-ꢀ), 7.36 (t, J ¼ 8.3 Hz, H-40), 7.90 (d, J ¼ 15.9Hz,
H-ꢂ), 13.08 (s, 20-OH) ppm; 13C NMR: ꢁ ¼ 16.4 (C-19), 18.6
(C-2), 21.7 (C-6), 23.8, 24.2 (C-16, C-17), 25.1 (C-20), 29.4
(C-15), 29.5 (C-7), 36.5 (C-3), 37.3 (C-10), 38.2 (C-1), 44.3 (C-
5), 47.5 (C-4), 51.9 (18-OCH3), 55.8 (60-OCH3), 101.4 (C-50),
110.9 (C-30), 111.8 (C-10), 123 (C-12), 124.6 (C-11), 133.1 (C-
14), 133.4 (C-ꢀ), 134.3 (C-8), 136 (C-40), 142.7 (C-ꢂ), 143.7
(C-13), 146.9 (C-9), 161 (C-60), 164.9 (C-20), 179 (C-18), 194.2
MS (EI): m=z (%) ¼ 566 (8) [M]þ , 523 (100), 475 (14), 433
ꢃ
(C¼O) ppm; MS (EI): m=z (%) ¼ 490 (11) [M]þ , 472 (76),
(10), 403 (11), 325 (10), 137 (47), 91 (90).
ꢃ
457 (13), 447 (83), 415 (19), 397 (40), 338 (21), 263 (16), 177
(23), 153 (44), 151 (100), 137 (18).
General method for the synthesis of 20-hydroxychalcones
6a–6c
NaH (7mg, 0.31 mmol) was added to a solution of the appro-
priate acetophenone (0.15 mmol) in 10 cm3 dry THF under
nitrogen. After stirring for 5 min, 50mg methyl 14-formylde-
hydroabietate (3) (0.15 mmol) were added and the reaction
mixture was stirred for 30h. After this period, the mixture
was poured into H2O and commercial HCl (pH of resulting
mixture adjusted to 2). This mixture was extracted with CHCl3
(3ꢅ30 cm3), the combined organic layers were dried with
anhydrous sodium sulfate, and the solvent was evaporated
to dryness. The residue was taken in 2 cm3 CH2Cl2 and puri-
fied by thin-layer chromatography using CH2Cl2 as eluent.
With 20-hydroxyacetophenone as starting material 6a was
obtained (52 mg, 75%); 20-hydroxy-60-methoxyacetophenone
gave 6b (48 mg, 65%), and 20-benzyloxy-60-hydroxyacetophe-
none gave 6c (36 mg, 42%).
Methyl 14-[2-(6-benzyloxy-2-hydroxybenzoyl)vinyl]dehydro-
abietate (6c, C37H42O5)
Yellow oil; 1H NMR: ꢁ ¼ 1.06, 1.09 (d, J ¼ 6.8 Hz, H-16,
H-17), 1.23 (s, H-20), 1.26 (s, H-19), 1.33–1.79 (m, H-
1,2,3,6), 2.18 (dd, J ¼ 2.1, 12.5 Hz, H-5), 2.34 (d, J ¼
12.0Hz, H-1), 2.63–2.70 (m, H-7), 3.15 (heptet, J ¼ 6.8 Hz,
H-15), 3.60 (s, 18-OCH3), 5.15 (s, 60-OCH2Ph), 6.42 (d, J ¼
8.1 Hz, H-50), 6.62 (dd, J ¼ 0.8, 8.1 Hz, H-30), 7.08–7.17
(m, H-300,500, H-400, H-12), 7.21–7.26 (m, H-200,600, H-11),
7.31 (t, J ¼ 8.1 Hz, H-40), 7.39 (d, J ¼ 15.8 Hz, H-ꢀ), 7.85 (d,
J ¼ 15.8 Hz, H-ꢂ), 13.14 (s, 20-OH) ppm; 13C NMR: ꢁ ¼ 16.4
(C-19), 18.6 (C-2), 21.6 (C-6), 23.7, 24.1 (C-16, C-17), 25.1
(C-20), 29.3 (C-15), 29.4 (C-7), 36.5 (C-3), 37.3 (C-10), 38.2
(C-1), 44.3 (C-5), 47.5 (C-4), 51.9 (18-OCH3), 70.9 (60-
OCH2Ph), 102.4 (C-30), 111.1 (C-50), 112 (C-10), 123 (C-400),
124.5 (C-11), 126.9 (C-200,600), 128 (C-12), 128.5 (C-300,500),
132.9 (C-14), 133.7 (C-ꢀ), 134 (C-8), 135.7 (C-100), 136 (C-
40), 142.6 (C-ꢂ), 143.7 (C-13), 146.7 (C-9), 160 (C-60), 165 (C-
20), 178.9 (C-18), 194.3 (C¼O) ppm; MS (EI): m=z (%) ¼ 566
Methyl 14-[2-(2-hydroxybenzoyl)vinyl]dehydroabietate
(6a, C30H36O4)
Yellow oil; 1H NMR: ꢁ ¼ 1.19, 1.23 (2d, J ¼ 6.8 Hz, H-16, H-
17), 1.24 (s, H-20), 1.27 (s, H-19), 1.30–1.83 (m, H-1,2,3,6),
2.23 (dd, J ¼ 2.0, 12.5 Hz, H-5), 2.33 (d, J ¼12.5Hz, H-1),
2.73–2.78 (m, H-7), 3.17 (heptet, J ¼ 6.8 Hz, H-15), 3.65
(s, 18-OCH3), 6.91 (ddd, J ¼ 1.1, 7.7, 7.9 Hz, H-50), 7.03
(dd, J ¼ 1.1, 8.1 Hz, H-30), 7.18 (d, J ¼ 15.9 Hz, H-ꢀ), 7.20
(d, J ¼ 8.3Hz, H-12), 7.29 (d, J ¼ 8.3 Hz, H-11), 7.49 (ddd,
J ¼ 1.5, 7.7, 8.1 Hz, H-40), 7.79 (dd, J ¼ 1.5, 7.9 Hz, H-60),
8.03 (d, J ¼ 15.9Hz, H-ꢂ), 12.78 (s, 20-OH) ppm; 13C
NMR: ꢁ ¼ 16.4 (C-19), 18.5 (C-2), 21.6 (C-6), 23.8, 24.2
(C-16, C-17), 25 (C-20), 29.4 (C-7), 29.6 (C-15), 36.4
(C-3), 37.2 (C-10), 38.1 (C-1), 44.2 (C-5), 47.4 (C-4), 51.9
(18-OCH3), 118.6 (C-30), 118.9 (C-50), 119.7 (C-10), 123.1 (C-
12), 124.9 (C-11), 126.5 (C-ꢀ), 129.7 (C-60), 132.8 (C-14),
133.8 (C-8), 136.5 (C-40), 143.6 (C-13), 145.6 (C-ꢂ), 147 (C-
9), 163.7 (C-20), 178.9 (C-18), 193.3 (C¼O) ppm; MS (EI):
(26) [M]þ , 548 (38), 523 (82), 475 (51), 457 (30), 431 (10),
ꢃ
425 (14), 415 (28), 397 (30), 383 (11), 339 (13), 338 (13), 325
(10), 263 (17), 227 (24), 138 (10), 137 (90), 91 (100).
General method for the synthesis of flavones 5a–5d and 7a–7d
Iodine (0.5mg) was added to a solution of the appropriate
chalcone 4a–4c and 6a–6c (0.10 mmol) in 2 cm3 DMSO under
nitrogen. The reaction mixture was heated at reflux during the
necessary time. After this period, the mixture was poured into
H2O with some crystals of sodium thiosulfate. This mixture
was extracted with CHCl3 (3ꢅ30cm3), the combined organic
layers were dried with anhydrous sodium sulfate, and the
solvent was evaporated to dryness. The residue was taken in
3 cm3 CH2Cl2 and purified by thin-layer chromatography
using CH2Cl2 as eluent. With 4a as starting material 5a was

Synthesis of flavonoid-type compounds
1125
obtained (38 mg, 84%) after 30 min of reaction; 4b gave 5b
(42 mg, 87%) after 30 min of reaction, 4c gave 5c (51 mg,
90%) and 5d (3mg, 5%) after 15min of reaction and gave 5d
(41 mg, 87%) after 2 h of reaction, 6a gave 7a (14 mg, 30%)
after 30min of reaction, 6c gave 7c (3mg, 5%) after 15 min of
reaction and gave 7d (5mg, 10%) after 2 h of reaction.
OCH3), 70.8 (20-OCH2Ph), 108.5 (C-80), 110.5 (C-30), 113.6
(C-60), 115 (C-100), 125.5 (C-11), 126.6 (C-200,600), 126.7
(C-14), 127.6 (C-400), 128.5 (C-300,500), 129.2 (C-12), 133.5
(C-70), 136.6 (C-100), 138.3 (C-8), 144.4 (C-13), 147.4 (C-9),
158.5 (C-90), 158.6 (C-50), 165 (C-20), 178.1 (C-40), 178.9 (C-
18) ppm; MS (EI): m=z (%) ¼ 564 (100) [M]þ , 563 (19), 487
ꢃ
Methyl 12-[2-(5-hydroxychromonyl)]dehydroabietate
(11), 474 (20), 459 (19), 458 (32), 443 (10), 399 (16), 384
(10), 383 (29), 137 (13), 91 (76).
Methyl 12-(2-chromonyl)dehydroabietate (5a, C30H34O4)
Yellow oil; 1H NMR: ꢁ ¼ 1.24 (s, H-20), 1.25, 1.28 (2d,
J ¼ 6.8 Hz, H-16, H-17), 1.29 (s, H-19), 1.41–1.94 (m,
H-1,2,3,6), 2.25 (dd, J ¼ 2.2, 12.5 Hz, H-5), 2.29 (d, J ¼
13.1Hz, H-1), 2.94–2.99 (m, H-7), 3.11 (heptet, J ¼ 6.8 Hz,
H-15), 3.68 (s, 18-OCH3), 6.45 (s, H-30), 7.10 (s, H-14), 7.29
(s, H-11), 7.44 (ddd, J ¼ 1.0, 7.7, 7.9 Hz, H-60), 7.47 (d, J ¼
7.7 Hz, H-80), 7.69 (dt, J ¼ 1.7, 7.7 Hz, H-70), 8.27 (dd, J ¼ 1.7,
7.9 Hz, H-50) ppm; 13C NMR: ꢁ ¼ 16.5 (C-19), 18.4 (C-2),
21.4 (C-6), 24.1, 24.3 (C-16, C-17), 25.1 (C-20), 29.9 (C-7),
29.9 (C-15), 36.6 (C-3), 37 (C-10), 37.8 (C-1), 44.6 (C-5),
47.5 (C-4), 52 (18-OCH3), 112 (C-30), 118.1 (C-80), 123.8
(C-100), 125.1 (C-11), 125.6 (C-50), 125.7 (C-50), 126.8 (C-
14), 129.6 (C-12), 133.6 (C-70), 138.4 (C-8), 144.4 (C-13),
147.4 (C-9), 156.4 (C-90), 167.5 (C-20), 178.4 (C-40), 178.9
(5d, C30H34O5)
Yellow oil; 1H NMR: ꢁ ¼ 1.24 (s, H-20), 1.25, 1.28 (2d,
J ¼ 6.6Hz, H-16, H-17), 1.29 (s, H-19), 1.42–1.91 (m, H-
1,2,3,6), 2.24 (dd, J ¼ 2.1, 12.6 Hz, H-5), 2.29 (d, J ¼
14.7Hz, H-1), 2.94–2.99 (m, H-7), 3.09 (heptet, J ¼ 6.6 Hz,
H-15), 3.68 (s, 18-OCH3), 6.37 (s, H-30), 6.82 (d, J ¼ 8.3 Hz,
H-60), 6.91 (d, J ¼ 8.3 Hz, H-80), 7.11 (s, H-14), 7.27 (s, H-11),
7.54 (t, J ¼ 8.3 Hz, H-70), 12.62 (s, OH) ppm; 13C NMR: ꢁ ¼
16.4 (C-19), 18.4 (C-2), 21.4 (C-6), 24.1, 24.3 (C-16, C-17),
25.1 (C-20), 29.9 (C-7), 36.5 (C-3), 36.9 (C-10), 37.8 (C-1),
44.5 (C-5), 47.5 (C-4), 52 (18-OCH3), 107.1 (C-80), 110.4
(C-30), 110.7 (C-100), 111.3 (C-60), 125.5 (C-11), 126.9 (C-
14), 129 (C-12), 135.3 (C-70), 138.8 (C-8), 144.4 (C-13),
147.5 (C-9), 156.6 (C-90), 160.8 (C-50), 168.8 (C-20), 178.8
(C-18), 183.5 (C-40) ppm; MS (EI): m=z (%) ¼ 474 (100)
(C-18) ppm; MS (EI): m=z (%) ¼ 458 (64) [M]þ , 443 (52),
ꢃ
383 (100), 341 (12), 337 (28), 317 (18), 261 (10), 165 (11),
121 (43).
[M]þ , 459 (26), 400 (26), 399 (64), 357 (10), 337 (11), 333
ꢃ
(14), 137 (32).
Methyl 12-[2-(5-methoxychromonyl)]dehydroabietate
(5b, C31H36O5)
Methyl 14-(2-chromonyl)dehydroabietate (7a, C30H34O4)
1
Yellow oil; 1H NMR: ꢁ ¼ 1.23 (s, H-20), 1.23, 1.26 (2d,
J ¼ 6.8 Hz, H-16, H-17), 1.29 (s, H-19), 1.41–1.93 (m, H-
1,2,3,6), 2.24 (dd, J ¼ 2.2 and 12.6Hz, H-5), 2.29 (d, J ¼
15.8Hz, H-1), 2.93–2.97 (m, H-7), 3.09 (heptet, J ¼ 6.8 Hz,
H-15), 3.67 (s, 18-OCH3), 4.01 (s, 50-OCH3), 6.36 (s, H-30),
6.84 (dd, J ¼ 0.7, 8.6 Hz, H-60), 7.02 (dd, J ¼ 0.7, 8.6 Hz, H-
80), 7.08 (s, H-14), 7.27 (s, H-11), 7.56 (t, J ¼ 8.6 Hz, H-70)
ppm; 13C NMR: ꢁ ¼ 16.5 (C-19), 18.4 (C-2), 21.4 (C-6),
24.1, 24.3 (C-16, C-17), 25.1 (C-20), 29.9 (C-7), 36.6 (C-
3), 37 (C-10), 37.9 (C-1), 44.6 (C-5), 47.5 (C-4), 52 (18-
OCH3), 56.5 (20-OCH3), 106.3 (C-80), 110.2 (C-30), 113.5
(C-60), 114.5 (C-100), 125.6 (C-11), 126.7 (C-14), 129.2 (C-
12), 133.6 (C-70), 138.3 (C-8), 144.4 (C-13), 147.4 (C-9),
158.5 (C-90), 159.8 (C-50), 165.2 (C-20), 178.3 (C-40), 178.9
Yellow oil; H NMR: ꢁ ¼ 1.16 (d, J ¼ 6.8 Hz, H-16, H-17),
1.21, 1.20 (d, J ¼ 6.8 Hz, H-16, H-17), 1.26 (s, H-19), 1.26
(s, H-20), 1.31–1.84 (m, H-1,2,3,6), 2.23 (dd, J ¼ 1.9 and
12.2Hz, H-5), 2.26 (dd, J ¼ 2.0, 12.2Hz, H-5), 2.35 (d,
J ¼ 12.0 Hz, H-1), 2.76–2.80 (m, H-7), 2.82 (heptet, J ¼
6.8 Hz, H-15), 2.90 (hept, J ¼ 6.8 Hz, H-15), 3.63 (s, 18-
OCH3), 3.65 (s, 18-OCH3), 6.35 (s, H-30), 6.36 (s, H-30),
7.24 (d, J ¼ 8.4 Hz, H-12), 7.42 (d, J ¼ 8.4 Hz, H-11), 7.45
(ddd, J ¼ 0.9, 7.7, 7.9 Hz, H-60), 7.48 (d, J ¼ 8.0 Hz, H-80),
7.70 (ddd, J ¼ 1.7, 7.7, 8.0 Hz, H-70), 8.29 (dd, J ¼ 1.7,
7.9 Hz, H-50) ppm; 13C NMR: ꢁ ¼ 16.3, 16.4 (C-19), 18.5
(C-2), 21.2, 21.3 (C-6), 23.9, 24.1, 24.2, 24.5 (C-16, C-17),
25.1 (C-20), 27.7, 28.3 (C-7), 30.4, 30.5 (C-15), 36.4, 36.5
(C-3), 37.3, 37.4 (C-10), 38.0, 38.1 (C-1), 44.2 (C-5), 47.5
(C-4), 51.9, 52.0 (18-OCH3), 113.5, 113.8 (C-30), 118.2,
118.3 (C-80), 123.2 (C-12), 123.88, 123.91 (C-100), 125.3
(C-60), 125.7, 125.8 (C-50), 126.8, 126.9 (C-11), 131.2 (C-
14), 133.1, 133.2 (C-8), 133.7 (C-70), 144.5 (C-13), 144.6
(C-13), 147.4 (C-9), 156.8, 156.9 (C-90), 165.6, 165.7 (C-
20), 178.1, 178.2 (C-40), 178.8, 178.9 (C-18) ppm; MS (EI):
(C-18) ppm; MS (EI): m=z (%) ¼ 488 (100) [M]þ , 459
ꢃ
(10), 413 (21), 151 (13).
Methyl 12-[2-(5-benzyloxychromonyl)]dehydroabietate
(5c, C37H40O5)
Yellow oil; 1H NMR: ꢁ ¼ 1.23, 1.26 (2d, J ¼ 6.8 Hz, H-
16, H-17), 1.24 (s, H-20), 1.29 (s, H-19), 1.41–1.94 (m,
H-1,2,3,6), 2.25 (dd, J ¼ 2.2, 12.5Hz, H-5), 2.29 (d, J ¼
14.8Hz, H-1), 2.93–2.98 (m, H-7), 3.12 (heptet, J ¼ 6.8 Hz,
H-15), 3.68 (s, 18-OCH3), 5.32 (s, 50-OCH2Ph), 6.35 (s, H-30),
6.86 (dd, J ¼ 0.7, 8.4Hz, H-60), 7.02 (dd, J ¼ 0.7, 8.4 Hz,
H-80), 7.09 (s, H-14), 7.28 (s, H-11), 7.30–7.43 (m, H-
300,400,500), 7.50 (t, J ¼ 8.4 Hz, H-70), 7.64 (d, J ¼ 7.1 Hz, H-
200,600) ppm; 13C NMR: ꢁ ¼ 16.5 (C-19), 18.4 (C-2), 21.4
(C-6), 24.1, 24.3 (C-16, C-17), 25.1 (C-20), 29.9 (C-7), 36.6
(C-3), 37 (C-10), 37.8 (C-1), 44.6 (C-5), 47.5 (C-4), 52 (18-
m=z (%) ¼ 458 (48) [M]þ , 443 (39), 383 (100), 341 (10),
ꢃ
317 (13), 121 (36).
Methyl 14-[2-(5-benzyloxychromonyl)]dehydroabietate
(7c, C37H40O5)
1
Yellow oil; H NMR: ꢁ ¼ 1.16, 1.15 (d, J ¼ 6.8 Hz, H-16, H-
17), 1.21 (d, J ¼ 6.9 Hz, H-16, H-17), 1.26 (s, H-19), 1.26 (s,
H-20), 1.29–1.83 (m, H-1,2,3,6), 2.19–2.32 (m, H-5), 2.34 (d,
J ¼ 11.6 Hz, H-1), 2.65–2.99 (m, H-7, H-15), 3.63 (s, 18-
OCH3), 3.65 (s, 18-OCH3), 5.32 (s, 50-OCH2Ph), 6.24 (s,

1126
S. M. C. S. Monteiro et al.
H-30), 6.26 (s, H-30), 6.88 (d, J ¼ 8.2 Hz, H-60), 7.03 (d, J ¼
8.2 Hz, H-80), 7.22 (d, J ¼ 8.5 Hz, H-12), 7.31 (t, J ¼ 7.3 Hz,
H-400), 7.39–7.44 (m, H-300, 500, H-11), 7.51 (t, J ¼ 8.2 Hz, H-
70), 7.66 (d, J ¼ 7.5 Hz, H-200,600) ppm; 13C NMR: ꢁ ¼ 16.38,
16.44 (C-19), 18.5 (C-2), 21.3, 21.4 (C-6), 23.9, 24.1, 24.2,
24.4 (C-16, C-17), 25.2 (C-20), 27.7, 28.3 (C-7), 30.4,
30.5 (C-15), 36.4, 36.6 (C-3), 37.3, 37.4 (C-10), 38.05,
38.13 (C-1), 44.3 (C-5), 47.5 (C-4), 52.0, 52.1 (18-
OCH3), 70.8 (20-OCH2Ph), 108.3, 108.4 (C-60), 110.6,
110.7 (C-80), 115.1 (C-30,100), 115.4 (C-30), 123.1 (C-12),
126.6 (C-200,600), 126.76, 126.84 (C-11), 127.6 (C-400), 128.6
(C-300,500), 130.9 (C-14), 133.3, 133.4 (C-8), 133.6 (C-70),
136.6 (C-100), 144.6, 144.7 (C-13), 147.4 (C-9), 158.7 (C-
50,90), 159.0 (C-50), 163.1 (C-20), 177.8, 177.9 (C-40), 178.8,
Curto MJ, Lobo AM, Prabhakar S, Slawin AJ, Rezpa HS,
Williams DJ (1989) J Nat Prod 52:85
3. Franich RA, Gagdil PD (1983) Physiol Plant Pathol
23:183
4. Savluchinske-Feio S, Nunes L, Pereira PT, Silva AM,
Roseiro JC, Gigante B, Curto MJM (2007) J Microbiol
Methods 70:465
5. Pratt YT (1951) J Chem Soc C 73:3803
6. Fieser LF, Campbell WP (1939) J Chem Soc C 61:2528
7. Akita H, Oishi T (1981) Chem Pharm Bull 29:1567
8. Akita H, Oishi T (1981) Chem Pharm Bull 29:1580
9. a) Moiteiro C, Fonseca N, Curto MJM, Tavares R,
Lobo AM, Ribeiro-Claro P, Feliz V, Drew MGB (2006)
Tetrahedron Asymmetry 17:3248; b) Tashima T, Toriumi
Y, Mochizuki Y, Nonomura T, Nagaoka S, Furukawa K,
Tsuru H, Adachi-Akahane S, Ohwada T (2006) Bioorg
Med Chem 14:8014; c) Fernandes M, Esteves M, Gigante
B. Chattopdhyay N (2007) J Fluoresc 7:31
179.0 (C-18) ppm; MS (EI): m=z (%) ¼ 564 (100) [M]þ
,
ꢃ
487 (12), 474 (15), 459 (18), 458 (29), 399 (15), 384 (11),
383 (18), 137 (12), 91 (59).
10. Bohm BA (1994) In: Harborne JB (ed) The Flavonoids –
Advances in Research Since 1986, Chapman and Hall,
London, p 387
Methyl 14-[2-(5-hydroxychromonyl)]dehydroabietate
(7d, C30H34O5)
Yellow oil; 1H NMR: ꢁ ¼ 1.16, 1.15 (d, J ¼ 6.8 Hz, H-16,
H-17), 1.21 (d, J ¼ 6.9Hz, H-16, H-17), 1.26 (s, H-19), 1.26
(s, H-20), 1.38–1.84 (m, H-1,2,3,6), 2.18–2.26 (m, H-5), 2.34
(d, J ¼ 11.8 Hz, H-1), 2.64–2.88 (m, H-7, H-15), 3.63 (s, 18-
OCH3), 3.65 (s, 18-OCH3), 6.28 (s, H-30), 6.29 (s, H-30), 6.85
(d, J ¼ 8.4 Hz, H-60), 6.91 (dd, J ¼ 0.6, 8.4 Hz, H-80), 7.23
(d, J ¼ 8.5 Hz, H-12), 7.42 (d, J ¼ 8.5 Hz, H-11), 7.54 (t,
J ¼ 8.4 Hz, H-70), 12.57 (s, OH) ppm; 13C NMR: ꢁ ¼ 16.38,
16.42 (C-19), 18.5 (C-2), 21.2, 21.3 (C-6), 23.9, 24.2, 24.5
(C-16, C-17), 25.1 (C-20), 28.4 (C-7), 30.5, 30.6 (C-15), 36.4,
36.6 (C-3), 37.3, 37.4 (C-10), 38.0, 38.1 (C-1), 44.2, 44.3 (C-
5), 47.5 (C-4), 52.0, 52.1 (18-OCH3), 107.2, 107.3 (C-80),
110.8 (C-100), 111.5 (C-60), 112.1, 112.4 (C-30), 123.2 (C-
12), 127.1, 127.2 (C-11), 130.8 (C-14), 133.0, 133.2 (C-8),
135.4 (C-70), 144.5, 144.6 (C-13), 147.51, 147.54 (C-9), 157.1
(C-90), 160.9 (C-50), 167.2 (C-20), 178.9 (C-18), 183.35,
11. a) Dhar DN (1981) The Chemistry of Chalcones and
Related Compounds, Wiley, New York; b) Anto RJ,
Sukumaran K, Kuttan G, Rao MNA, Subbaraju V, Kuttan
R (1995) Cancer Lett 97:33; c) Parmar VS, Bisht KS, Jain
R, Singh S, Sharma KS, Gupta S, Malhotra S, Tyagi OD,
Vardhan A, Pati HN, Berghe DV, Vlietinck A (1996)
Indian J Chem 35B:220; d) Calliste CA, Le Bail JC,
Trouillas P, Pouget C, Habrioux G, Chuliqa AJ, Duroux
JL (2001) Anticancer Res 21:3949; e) Kumar A, Katiyar
SB, Agarwal A, Chauhan PMS (2003) Curr Med Chem
10:1137; f) Go ML, Wu, X, Liu, XL (2005) Curr Med
Chem 12:483; g) Gacche RN, Dhole NA, Kamble SG,
Bandgar BP (2007) J. Enz Inhib Med Chem 22:Doi:
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K, Mizukawa K, Kawamura A, Kondoh T, Hosoda K,
Kohmura E (2007) J Neuro-Oncol 85:123
183.43 (C-40) ppm; MS (EI): m=z (%) ¼ 474 (100) [M]þ
,
ꢃ
12. Silvestre AJD, Monteiro SMCS, Silva AMS, Cavaleiro
459 (18), 399 (88), 357 (13), 333 (17), 137 (38), 91 (27), 78
(21), 66 (16), 63 (24).
´
JAS, Felix V, Ferreira P, Drew MGB (1998) Monatsh
Chem 129:1183
13. a) Barros AIRNA, Silva AMS, Alkorta I, Elguero J (2004)
Tetrahedron 60:6513; b) Brito CM, Pinto DCGA, Silva
Acknowledgements
´
AMS, Silva AMG, Tome AC, Cavaleiro JAS (2006) Eur J
Thanks are due to the University of Aveiro, ‘‘Fundac°a˜o para a
^
Ciencia e Tecnologia’’ and FEDER for funding the Organic
Chemistry Research Unit. One of us (SMCSM) also thanks the
^
‘‘Fundac°a˜o para a Ciencia e Tecnologia’’ and FEDER for a
PhD grant (PRAXIS XXI=BD=15786=98).
Org Chem: 2558; c) Barros AIRNA, Silva AMS (2006)
Magn Reson Chem 44:1122; d) Patoilo DT, Silva AMS,
´
Pinto DCGA, Tome AC, Cavaleiro JAS (2007) J Hetero-
cycl Chem 44:1345; e) Pinto DCGA, Silva AMS,
Cavaleiro JAS, Synlett:1897
14. Meier H, Kretzschmann H, Kolshorn H (1992) J Org
Chem 57:6847
15. Silva AMS, Pinto DCGA, Cavaleiro JAS (1994) Tetra-
hedron Lett 35:5899
^
16. Ramalho L, Gigante B, Curto M, Florencio F (1995) Eur
Mass Spectrom 1:389
17. Mabry TJ, Ulubelen A (1980) In: Waller GR, Dermer OC
(eds) Biochemical Application of Mass Spectrometry, 1st
supplementary volume. John Wiley & Sons, New York,
p 1131
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