Prenylflavonoids and prenyl/alkyl-phloroacetophenones: Synthesis and antitumour biological evaluation

Article abstract of DOI:10.1016/j.ejmech.2010.06.025

Several prenylflavonoids have been synthesised and tested against human tumour cell lines. The prenyl unit has been geranyl or a labdane diterpene. These labdane-flavonoids have been synthesised for the first time. The antitumour activity increase with the prenylation at C-8 position. Twenty-three C and O-prenylated acylphloroglucinols have been synthesised as well. In this case the C-alkylation products have resulted, in general, more active.

Full text of DOI:10.1016/j.ejmech.2010.06.025

European Journal of Medicinal Chemistry 45 (2010) 4258e4269
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Prenylflavonoids and prenyl/alkyl-phloroacetophenones: Synthesis
and antitumour biological evaluationq
,
a
a
a
a
a
b
P. Basabe a , M. de Román , I.S. Marcos , D. Diez , A. Blanco , O. Bodero , F. Mollinedo ,
*
B.G. Sierra b c, J.G. Urones a
,
a Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad de Salamanca, Plaza de los Caídos 1-5, 37008 Salamanca, Spain
b Centro de Investigación del Cáncer, CSIC-Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
c APOINTECH, Campus Miguel de Unamuno, Universidad de Salamanca 37007 Salamanca, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Several prenylflavonoids have been synthesised and tested against human tumour cell lines. The prenyl
unit has been geranyl or a labdane diterpene. These labdane-flavonoids have been synthesised for the
first time. The antitumour activity increase with the prenylation at C-8 position. Twenty-three C and O-
prenylated acylphloroglucinols have been synthesised as well. In this case the C-alkylation products have
resulted, in general, more active.
Received 1 February 2010
Received in revised form
14 June 2010
Accepted 16 June 2010
Available online 23 June 2010
Ó 2010 Elsevier Masson SAS. All rights reserved.
Keywords:
Prenylflavonoids
Prenyl-phloroacetophenones
Antitumourals
C-Alkylation
Flavonoids
1. Introduction
interesting synthetic targets due to their biological activities. Many
of these compounds show affinity to P-glycoprotein and constitute
Nature is always an innovative laboratory. The combination of
two or more types of natural products leading to hybrid
compounds is not unusual [1]. This concept applied to chemical
synthesis is a promising approach in the development of novel
compounds either in medicine or in agrochemistry [2].
Many terpenoids are known to be biologically active [3,4], for
instance their anti-inflammatory properties [5e7] have been well
proven. Likewise, a wide range of bioactivities are described for
flavonoids [8e12]. As a result, the combination of these two types
of compounds could lead to more active hybrid compounds, or even
with new biological properties.
promising potential modulators of multidrug resistance. Another
series of C-isoprenylflavonoids show antiproliferative activity
against HT-29 human colonic cell line.
Several phloroacetophenone analogues, intermediates in the
synthetic pathway of flavonoids, have been reported from natural
sources [16]. Several of these compounds, such as thouvenol A and
thouvenol B (Fig. 1), isolated from Protorhus thouvenotii [17],
showed in vitro cytotoxicity against A2780 ovarian cancer cell lines.
Acylphloroglucinols present interesting biological properties
and they are both synthetically and biosynthetically related to
flavonoid. These facts motivated us to accomplish the synthesis of
an acyl phloroglucinol library with either a prenyl or alkyl moiety.
Besides, the evaluation of their biological activity as potential
antitumor agents is our final aim.
In this work we aimed the synthesis and biological evaluation as
antitumour agents of several terpenoideflavonoid hybrid
compounds.
The pharmacological activity of several prenylated flavonoids
has been reviewed by Botta [13]. Other previous studies by Barron
et al. [14,15] have shown that C-prenylated flavonoids are
2. Results and discussion
To start with, we studied Barron et al. conditions [14] in order to
optimize the alkylation of flavonols. Our fist attempt was the C-
prenylation of chrysin.
In addition to the C-alkylation products described by Barron et
al (5 and 6), compounds of C and O-alkylation 2, 3 and 4 were also
q
In memoriam of Prof. J. M. Concellón.
* Corresponding author. Tel.: þ34 923 294474; fax: þ34 923 294574.
E-mail address: pbb@usal.es (P. Basabe).
0223-5234/$ e see front matter Ó 2010 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2010.06.025

P. Basabe et al. / European Journal of Medicinal Chemistry 45 (2010) 4258e4269
4259
HO
OH
O
OH
HO
OH
OH
R4
HO
O
O
R3O
R2
O
O
3
3
11
8
i
O
OH
OH
OH
OR1
H
O
thouvenol A
OH
thouvenol B
7
Fig. 1.
R1
R2
R3
R4
H
%
8
9
Ger
Ger
H
H
Ger
1.0
H
H
H
H
H
H
Ger 6.0
Ger 6.0
H
2´
3
R3
O
= Ger
1
8
10
HO
O
R2O
R1
i
6´
11 Ger
4.0
6
Scheme 2. i) Me4NOH 10% aq. (3 equiv.), Et4NI (1 equiv.), MeOH, 7 times of15 s each,
OH
O
OH
O
MW (90 W), geranyl bromide (10 equiv.).
1
*
**
R1
R2
R3
%
%
2
3
4
5
6
Ger Ger Ger
Ger Ger
8.0
23.4
obtained in a big ratio. Therefore, it was necessary to reduce the
quantity of base to three equivalents. As shown in Scheme 2, 20% of
unreacted kaempherol and opening products were obtained. The
reaction mixture was purified as before and the products were
identified by spectroscopic methods. The spectroscopic data of 10
are identical to the natural compound isomacarangin, isolated from
Macaranga Schweinfurthii [18].
In order to achieve molecules with the prenyl group as a diter-
penoid, the alkylation of kaempheride, 13, was tested with 12,
a diterpene bromide obtained from sclareol [19]. In this case, the
microwave irradiation produced the decomposition of the diter-
pene moiety, so it was necessary to carry out the alkylation by
refluxing kaempheride with 0.80 equiv. of the diterpene bromide
12 in acetone and K2CO3 (0.30 equiv.) over 3 h [20]. The results are
presented in Scheme 3.
The reactions conditions established with kaempheride
(Scheme 3) were used in the case of kaempherol, obtaining
compounds of C and O-alkylation, as depicted in Scheme 4.
Either in the case of kaempheride, 13, or kaempherol, 7, it was
not possible to isolate any C-alkylation product at C-6. Therefore, in
order to obtain macarangin, 23, isolated from Macaranga denticu-
late [21] and Macaranga vedeliana [22] and denticulaflavonol, 24,
isolated from M. denticulate [21] as well, the total synthesis is
required. Denticulaflavonol is the first natural compound hybrid of
a diterpene and a flavonol. So as to achieve the synthesis of this
H
11.0
= Ger
21.1
H
Ger
H
Ger Ger 1.5
H
H
H
1.0
14.7
9.1
Ger 2.0
Scheme 1. *i) Me4NOH 10% aq. (10 equiv.), Et4NI (1 equiv.), MeOH, 6 times of 45 s each,
MW (160 W), geranyl bromide (1 equiv.); **i) Me4NOH 10% aq. (10 equiv.), Et4NI
(1 equiv.), MeOH, 6 times of 30 s each, MW (90 W), geranyl bromide (1 equiv.).
obtained. These molecules are interesting to develop SAR studies in
tumour cell lines.
The reaction mixtures were submitted to several chromato-
graphic stages yielding pure alkylated chrysin derivatives. The
compounds were identified on the basis of their spectroscopic data.
The alkylation position was determined by 1He13C heteronuclear
long-range correlations.
Once we had the pure alkylated chrysin derivatives on hand,
they were used for the HPLC analysis of the several reaction
mixtures obtained after varying reaction conditions. In our hands
the best conditions to achieve the C-alkylation products of chrysin
with geranyl bromide were 10 equiv. of base and 6 successive 30-s
microwave irradiations at 90 W Scheme 1 summarizes the results
obtained, recovering a 29.0% of unreacted chrysin.
The same reaction conditions for the C-alkylation of chrysin
with geranyl bromide (90 W, base 10 equiv.) were used with
kaempherol 7. In this case, as it is a flavonol, opening products were
compound, firstly it was necessary to obtain
oacetophenone 22, Scheme 5.
u-benzoyloxyphlor-
Br
OMe
OMe
R3
HO
O
O
R2O
O
O
i
+
OH
OR1
OH
OH
H
13
12
R1
14 Dt
R2
Dt
Dt
H
R3
%
= Dt
H
H
Dt
H
10.0
18.0
4.0
15
H
H
16
17 Dt
H
12.0
H
Scheme 3. i) K2CO3 (0.30 equiv.), 12 (0.8 equiv.), acetone, 74 ꢀC, 3 h.

4260
P. Basabe et al. / European Journal of Medicinal Chemistry 45 (2010) 4258e4269
Br
OH
OH
R3
HO
O
O
R2O
O
O
i
+
OH
OR1
OH
OH
R1
H
7
12
R2
R3
H
%
= Dt
18 Dt
Dt
Dt
H
9.0
19
H
H
H
17.0
5.0
20
Dt
H
21 Dt
H
10.0
H
Scheme 4. i) K2CO3 (0.30 equiv.), 12 (0.8 equiv.), acetone, 74 ꢀC, 3 h.
antifungal activity against Candida albicans [26]. The phlor-
oacetophenone 29 is also a natural compound isolated from San-
guisorba minor [27], and Prunus domestica [28].
Phloroacetophenone, 27, was also used to obtain several 3,3-
dimethylallyl derivatives. When the quantity of K2CO3 is sub-
stechiometric in the reaction, compounds with the prenyl chain
cyclised, 31e33, are obtained, Scheme 8. Nevertheless, if excess of
K2CO3 is used, the open-chain prenylderivatives 34e37 are
obtained, Scheme 9.
The diprenyl compound 31 had been previously synthesised
[29] from 27 by treatment with 3,3-dimethylallyl alcohol in
BF$3OEt2/HCOOH. Compounds 32 and 33 can be obtained from 27
with isoprene using Amberlyst-15 as catalyst [30]. The 1H NMR data
were totally coincident with the ones described in bibliography,
being described their 13C NMR data for the first time.
OH
R2
HO
OH
O
HO
R1
O
O
Ref. 19
OBz
OH
OH
OH
22
R1
23 Ger
10
R2
H
macarangin
H
Ger isomacarangin
24 Dt
20
H
denticulaflavonol
H
Dt
Scheme 5.
Compound 37 is identical to the natural product 6-O-deme-
thylacronylin, isolated from Acronychia laurifolia [31].
When 27 was treated with geranyl bromide under the Mios-
kowski conditions [32] for C-specific alkylation of phloroglucinol,
the C-geranyl derivatives, 38 and 39, were exclusively obtained,
Scheme 10.
In order to have quantities of kaempherol derivatives for SAR
studies, the methyl derivatives 25 and 26 were synthesised,
Scheme 6. Compound 25 was obtained by synthesis [23] and its
methylation with methyl iodide and K2CO3 under refluxing acetone
gave 26.
Once the
C
and O-alkylflavonoids described before were
The synthesis of some farnesyl derivatives of phlor-
oacetophenone 27 has been accomplished as well. If the alkylation
reactionof 27 withfarnesyl bromide iscarried outwithlack ofK2CO3,
a complex mixture is obtained, being only possible to isolate and
identify compound 40, whereas an excess of K2CO3 leads to the far-
nesyl derivatives 41e44, having an open terpene chain, Scheme 11.
The structure of the only diprenylated compound 41 has been
determined by bidimensional correlation experiments. Compounds
42 and 44 are natural products isolated from Boronia ramose [33].
Compound 44 had been previously synthesised from
obtained, the synthesis of a variety of acylphloroglucinols was
carried out for their evaluation as antitumourals.
First of all the methyl derivatives of phloroacetophenone, 27,
compounds 28e30, were obtained. The best results were achieved
by using excess of TMSCHN2 in a mixture of chloroform/methanol
as solvent [24]. The major product under these conditions was 29,
Scheme 7.
The compounds were identified by their spectroscopic data.
Xanthoxylin, 28, isolated from Xanthoxylum piperitum [25], exhibits
OR1
R2
HO
OH
O
1
i
R3O
O
OR2
O
OH
OH
27
OH
R1
O
R1
28 Me Me
29
Me 48.0
3.0
R2
%
R2
R3
H
9.0
H
25 Me Me
i
26 Me Me Me
30 Me
H
Scheme 6. i) MeI (4 equiv.), K2CO3 (4 equiv.), acetone, 74 ꢀC.
Scheme 7. i) TMSCHN2 (3.0 equiv.), CHCl3/MeOH, 14 h.

P. Basabe et al. / European Journal of Medicinal Chemistry 45 (2010) 4258e4269
4261
HO
OH
O
O
OH
O
O
O
O
HO
O
O
i
+
+
OH
OH
OH
OH
27
31 (5.5%)
32 (6.0%)
33 (22.5%)
Scheme 8. i) K2CO3 (0.60 equiv.), 3,3-dimethylallyl bromide (0.8 equiv.), acetone, 74 ꢀC, 2 h.
phloroacetophenone 27 in five steps [34]. In order to obtain
a variety of acylphloroglucinols for SAR studies, we decided to
alkylate phloroacetophenone 27 with longer chains (18 carbon
atoms) having and not having a double bond. Consequently, it is
necessary to prepare the proper bromoderivatives 46 and 48,
obtained from alcohols 45 and 47 respectively by treatment with
CBr4/PPh3 [35], Scheme 12.
The alkylation products of 27 with the bromides 46 and 48 were
achieved in low yield because these bromides are quite unreactive,
they are not allyl bromides as in the previous reactions. Never-
theless, the quantities of the alkylacetophenones 49e55, Scheme
13, were enough to carry out the biological tests.
C-6 or C-8 in the A ring makes compounds 5 and 6 be active in the
three cellular lines. Blocking the hydroxyl group at C-7 by the
prenyl chain keeps the activity, while there is a prenyl chain at C-6,
2 and 3.
Kaempherol, 7, is inactive, however the introduction of a methyl
group at C-40, 13, or at C-3, C-40, 25, or at C-3, C-7, C-40, 26, made the
resulting compounds active in the three cellular lines, Table 2.
Table 3 collects the activity results for the C and O-alkylation of
kaempherol with diterpene units, compounds 18, 19, 20, 21 and 24,
or with geranyl units, compounds 8, 9, 10, 11 and 23, are collected.
Regarding compounds with diterpene units, only 20 and 21 are
active. Compound 20 is C-alkylated at C-8 and 21 is O-alkylated at
C-3. The others, including denticulaflavonol 24, a C-alkylated
product, are inactive. The comparison of the geranyl derivatives
(compounds 8e11 and 23) shows that, as before, the alkylation at
C-8, 10, made the compound active, while the C-6 alkylated
derivative 23 is inactive. In the same way as occurred with the
diterpenic units, the introduction of a geranyl at the hydroxyl group
of C-3, O-alkylation compound 11, made this compound active. The
same happened to 9, which has a geranyl unit at C-8 and another at
the hydroxyl group of C-3. Block of the hydroxyl groups of C-3 and
3. Biological evaluation
The in vitro antitumour activity for the compounds was deter-
mined by measurement of their cytotoxic properties in human
tumour cell lines by XTT assay. The cell lines used were HeLa
(human epitheloid cervix carcinoma), A549 (human lung carci-
noma) and HT-29 (human colon carcinoma), and HL-60 (human
myeloid leukaemia).
C-7 by the prenyl unit, compounds
8 and 18, made these
Cells were incubated in DMEM (HeLa, A549, HT-29) or
RPMI1640 (HL-60) culture medium containing 10% heat-inacti-
vated fetal bovine serum in the absence and in the presence of the
indicated compounds at a concentration range of 10ꢁ4e10ꢁ8 M in
a 96-well plate, and following 72 h of incubation at 37 ꢀC in
a humidified atmosphere of air/CO2 (19/1) the XTT assay was per-
formed. Measurements were done in triplicate, and the IC50 value,
defined as the drug concentration required to cause 50% inhibition
in the cellular proliferation with respect to the untreated controls,
was determined for each compound.
Data of Tables 1e10 are shown as the mean values ꢂ S.D. of three
independent determinations. The active compounds shown a rela-
tively modest antitumour activity when compared to widely used
doxorubicin antitumour agent, which showed IC50 values of
2.9 ꢂ 0.2 ꢃ 10ꢁ7 M, 2.6 ꢂ 0.3 ꢃ 10ꢁ7 M and 3.0 ꢂ 0.2 ꢃ 10ꢁ7 M for
HeLa, A549 and HT-29 cell lines (mean values ꢂ S.D. n ¼ 3).
As it can be seen in the results shown in Table 1, chrysin, 1, is
selectively active for HeLa cells. The introduction of geranyl chain at
compounds inactive. Only the blocking of the hydroxyl at C-7, 19,
made this compound be inactive as well. The results indicate that in
this case of C and O-alkylation of kaempherol with diterpene or
geranyl units, the presence of the free hydroxyl at C-7 is crucial for
the activity.
In the kaempheride derivatives, Table 4, the introduction of
diterpene unit at C and O-alkylation (14e16) lead to a lost of
activity, except if the diterpene unit is found at the hydroxyl group
of C-3, 17.
By comparison of the obtained results with kaempherol and
kaempheride derivatives, Tables 3 and 4 respectively, seem to
conclude that the free hydroxyl group at C-7 favours the activity (9,
10, 11, 20, 21, 13 and 17).
The results obtained with the acylphloroglucinols are collected
in Table 5.
The phloroacetophenone 27 and its O-methyl derivatives 28 and
29 are inactive against the four cellular lines. Derivative 30 shows
activity against HeLa cells.
Compounds 32 and 33, in which the dimethylallyl chain has
cyclised with the hydroxyl group in ortho position, are inactive.
R4
R3O
R2
OR1
O
HO
OH
O
i
OH
OH
27
R1
H
R2
R3
R4
%
34
35
3,3-DMA
H
H
3,3-DMA 6.0
H
3,3-DMA
H
H
H
2.0
0.6
= 3,3-DMA
36 3,3-DMA
H
H
H
37
H
3,3-DMA
20.0
Scheme 9. i) K2CO3 (1.10 equiv.), 3,3-dimethylallyl bromide (0.8 equiv.), acetone,
74 ꢀC, 4 h.
Scheme 10. i) NaOH aq. (2.0 equiv.), geranyl bromide (0.5 equiv.), EtOH, THF, 12 h.

4262
P. Basabe et al. / European Journal of Medicinal Chemistry 45 (2010) 4258e4269
Scheme 11. i) K2CO3 (0.90 equiv.), farnesyl bromide (0.80 equiv.), acetone, 74 ꢀC, 2 h; ii) K2CO3 (2.0 equiv.), farnesyl bromide (0.45 equiv.), acetone, 74 ꢀC, 4 h.
Table 2
Inhibition of proliferation of human tumour cell lines by kaempferol and methyl
derivatives.
i
OH
OH
Br
7
7
7
7
Compound
IC50 (10ꢁ5 M)
HeLa
45
46 (99%)
A549
HT-29
i
7
>10
>10
>10
13
25
26
2.3 ꢂ 0.1
3.1 ꢂ 0.1
2.8 ꢂ 0.3
2.2 ꢂ 0.1
3.1 ꢂ 0.1
3.0 ꢂ 0.1
3.2 ꢂ 0.1
3.2 ꢂ 0.1
2.6 ꢂ 0.5
Br
48 (97%)
15
15
47
Scheme 12. i) CBr4 (1.25 equiv.), PPh3 (1.70 equiv.), DCM, r.t., 10 min.
Scheme 13. i) K2CO3 (0.60 equiv.), 46 (0.80 equiv.), acetone, 74 ꢀC, 9 h; ii) K2CO3 (0.60 equiv.), 48 (0.80 equiv.), acetone, 74 ꢀC, 3 h.
Compound 31, with two dimethylallyl cyclised units, is selectively
active for cellular lines HT-29 and HL-60. Regarding the O-alkylated
derivatives, only 35 is active, except for the cellular line A549. The
C-alkylated acyl phloroglucinol 37 is active in all the cellular lines. It
can be concluded that the activity requires the presence of free
hydroxyl phenolic groups and the introduction of an alkyl chain in
the aromatic ring. This fact agrees with the results showed in Table
7 for the geranyl phloroacetophenone derivatives.
Compounds 38 and 39, which have free hydroxyl groups and
one or two geranyl units respectively in the aromatic ring, are
actives in the four cellular lines Table 7.
Compound, 40, with the chain cyclised with the ortho hydroxyl
group is more selective (only active against HeLa and HL-60)
Table 8. The derivative, 44, with a farnesyl unit in the aromatic ring
Table 3
Inhibition of proliferation of human tumour cell lines by C and O-alkyl kaempferol
derivatives.
Compound
IC50 (10ꢁ5 M)
HeLa
Table 1
A549
HT-29
Inhibition of proliferation of human tumour cell lines by chrysin and derivatives.
18
19
20
21
24
8
>10
>10
3.0 ꢂ 0.3
2.7 ꢂ 0.2
>10
>10
>10
3.2 ꢂ 0.1
2.6 ꢂ 0.2
>10
>10
>10
Compound
IC50 (10ꢁ5 M)
HeLa
2.9 ꢂ 0.3
3.0 ꢂ 0.2
>10
3.1 ꢂ 0.3
3.0 ꢂ 0.2
3.0 ꢂ 0.2
2.5 ꢂ 0.1
>10ꢁ4
A549
HT-29
1
2
3
4
5
6
2.9 ꢂ 0.2
3.0 ꢂ 0.2
3.0 ꢂ 0.1
>10
ꢄ10
>10
2.9 ꢂ 0.1
3.2 ꢂ 0.1
>10
3.2 ꢂ 0.1
3.2 ꢂ 0.1
>10
>10
>10
9
2.7 ꢂ 0.2
3.0 ꢂ 0.1
2.3 ꢂ 0.1
>10ꢁ4
2.6 ꢂ 0.2
2.6 ꢂ 0.2
2.7 ꢂ 0.1
>10ꢁ4
10
11
23
3.2 ꢂ 0.1
3.2 ꢂ 0.1
3.3 ꢂ 0.1
1.9 ꢂ 0.1
2.8 ꢂ 0.5
3.2 ꢂ 0.1

P. Basabe et al. / European Journal of Medicinal Chemistry 45 (2010) 4258e4269
4263
Table 4
Table 8
Inhibition of proliferation of human tumour cell lines by prenyl derivatives of
kaempheride.
Inhibition of proliferation of human tumour cell lines by farnesyl derivatives of 27.
Compound
IC50 (10ꢁ5 M)
HT-29
Compound
IC50 (10ꢁ5 M)
HeLa
A549
HeLa
HL-60
A549
HT-29
40
41
42
43
44
>10
>10
3.1 ꢂ 0.1
2.9 ꢂ 0.3
1.8 ꢂ 0.7
>10
>10
3.2 ꢂ 0.1
3.2 ꢂ 0.1
2.2 ꢂ 0.6
3.0 ꢂ 0.1
>10
2.9 ꢂ 0.1
3.1 ꢂ 0.1
1.3 ꢂ 0.1
3.1 ꢂ 0.1
3.2 ꢂ 0.1
3.2 ꢂ 0.1
3.1 ꢂ 0.1
1.4 ꢂ 0.4
13
14
15
16
17
2.3 ꢂ 0.1
>10
>10
>10
3.0 ꢂ 0.1
2.2 ꢂ 0.1
>10
>10
>10
3.0 ꢂ 0.1
3.2 ꢂ 0.1
>10
>10
>10
3.2 ꢂ 0.1
Table 9
Inhibition of proliferation of human tumour cell lines by oleyl derivatives of 27.
Table 5
Inhibition of proliferation of human tumour cell lines by phloroacetophenone 27
and methyl derivatives.
Compound
IC50 (10ꢁ5 M)
HT-29
Compound
IC50 (10ꢁ5 M)
HT-29
A549
HeLa
HL-60
A549
HeLa
HL-60
49
50
51
52
>10
>10
>10
>10
3.1 ꢂ 0.1
3.1 ꢂ 0.1
3.1 ꢂ 0.1
3.1 ꢂ 0.1
>10
3.2 ꢂ 0.1
3.2 ꢂ 0.1
>10
27
28
29
30
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
1.3 ꢂ 0.3
>10
>10
>10
>10
>10
>10
>10
>10
Table 10
Table 6
Inhibition of proliferation of human tumour cell lines by stearyl derivatives of 27.
Inhibition of proliferation of human tumour cell lines by 3,3-dimethylallyl deriva-
tives of 27.
Compound
IC50 (10ꢁ5 M)
HT-29
Compound
IC50 (10ꢁ5 M)
HT-29
A549
HeLa
HL-60
A549
HeLa
HL-60
53
54
55
>10
>10
2.6 ꢂ 0.2
>10
>10
>10
>10
>10
>10
31
32
33
34
35
36
37
3.2 ꢂ 0.1
>10
>10
>10
>10
>10
>10
>10
>10
2.9 ꢂ 0.1
>10
>10
>10
>10
3.1 ꢂ 0.1
>10
>10
3.2 ꢂ 0.1
2.8 ꢂ 0.1
3.1 ꢂ 0.1
>10
>10
3.1 ꢂ 0.1
3.0 ꢂ 0.2
3.2 ꢂ 0.1
>10
>10
>10
4. Conclusions
3.0 ꢂ 0.1
2.8 ꢂ 0.2
3.2 ꢂ 0.1
A series of C and O-prenylflavonoids has been synthesised and
tested the antitumour activity against four cellular lines of human
tumours. It is the first time that hybrid compounds between
flavonoids and labdane diterpenes have been synthesised and
tested for antitumoural activity. The biological activities are
moderate and in many cases do not allow definitive conclusions.
However seems that in the flavone chrysin, the C-prenylation at C-6
or C-8 favours the activity, Table 1. In the case of kaempherol, the
methoxylation of the phenol groups favours the activity, Table 2,
however none of the C-7 prenylderivatives are actives, Table 3. For
the acylphloroglucinols, the alkylation in the aromatic ring favours
the activity as well, except for the oleyl derivatives.
and three free hydroxyl groups, is active in the four cellular lines.
The mono O-alkylation derivatives 42 and 43 are actives, while
compound 41 which possess two farnesyl units is inactive against
three of the four cellular lines.
Tables 9 and 10 collect the activities of the acylphloroglucinols
with an alkyl chain of 18 carbon atoms with one double bond, Table
9, or without double bonds, Table 10.
In the case of the oleyl derivatives, Table 9, the introduction of
two O-alkyl groups made that the compound was inactive, 49.
Compound 50, with only one O-alkyl group, is active against the
four cellular lines. The mono O-alkylated derivative, 51, is selec-
tively active against HeLa and HL-60. In the case of the C-alkylated
derivative 52, this compound is inactive.
5. Experimental
When there is an 18 carbon atoms saturated chain, Table 10, the
O-alkylation derivatives 53 and 54 are inactive, while the C-alkyl-
ation derivative, 55, is active against the four cellular lines as
occurred with compounds 37, 39 and 44.
5.1. General methods
Unless otherwise stated, all chemicals were purchased as the
highest purity commercially available and were used without
further purification. IR spectra were recorded on a AVATAR 370 FTIR
Thermo Nicolet spectrophotometer. Melting points are uncor-
rected. 1H and 13C NMR spectra were performed in CDCl3, unless
other solvent is stated, and referenced to the residual peak of CHCl3
Table 7
Inhibition of proliferation of human tumour cell lines by geranyl derivatives of 27.
Compound
IC50 (10ꢁ5 M)
HT-29
at
Varian 200 VX and Bruker DRX 400 instruments. Chemical shifts
are reported in ppm and coupling constants (J) are given in hertz.
HRMS were recorded on a quadruple-time of flight QSTAR XL
d 7.26 ppm and d
77.0 ppm, for 1H and 13C, respectively, using
A549
HeLa
HL-60
38
39
3.1 ꢂ 0.2
2.1 ꢂ 0.1
3.2 ꢂ 0.1
2.0 ꢂ 0.1
2.0 ꢂ 0.1
1.9 ꢂ 0.1
1.9 ꢂ 0.1
1.9 ꢂ 0.1
d

4264
P. Basabe et al. / European Journal of Medicinal Chemistry 45 (2010) 4258e4269
spectrometer using electrospray (ESI) technique with MeOH as
solvent. Optical rotations were determined on a PerkineElmer 241
polarimeter in 1 dm cells. THF was distilled from sodium and
dichloromethane was distilled from calcium hydride under argon
atmosphere. Microwave irradiations were realized in a domestic
oven (1150 W) at 90 W and 160 W by successive periods of 15 and
30 s.
5.2.4. 6-C-Geranylchrysin (5)
IR (film, cmꢁ1): 3405, 2923, 1643, 1613, 1580, 1462, 1448,
1348, 1310, 1245, 1179, 1072; 1H NMR (400 MHz, CDCl3)
d 13.11
(1H, s), 7.88 (2H, dd, J ¼ 7.6, 1.5 Hz), 7.55e7.49 (3H, m), 6.66 (1H,
s), 6.50 (1H, s), 6.35 (1H, s), 5.30 (1H, t, J ¼ 7.2 Hz), 5.06 (1H, t,
J ¼ 5.5 Hz), 3.49 (2H, d, J ¼ 7.2 Hz), 2.18e2.11 (4H, m), 1.84 (3H,
s), 1.68 (3H, s), 1.60 (3H, s); 13C NMR (100 MHz, CDCl3)
d 182.6,
163.8, 161.7, 159.1, 156.0, 140.0, 132.1, 131.7, 131.4, 129.0 (2C),
126.2 (2C), 123.6, 120.9, 109.9, 105.6, 105.3, 94.4, 39.7, 26.3, 25.6,
21.4, 17.7, 16.2; HRMS calcd for C25H26O6 (Mþ þ Na) 413.1723,
found 413.1715.
5.2. Geranylated chrysin derivatives (2e6)
To a solution of 0.5 g of chrysin (2.0 mmol) in 5.0 mL of methanol
and 10.0 mL of 10% aqueous tetramethylammonium hydroxide was
added 0.5 g of tetraethylammonium iodide (2.0 mmol). After
5.2.5. 8-C-Geranylchrysin (6)
homogenization, 400
mL of geranyl bromide (2.0 mmol) was added
IR (film, cmꢁ1): 3405, 2923, 1643, 1613, 1580, 1462, 1448, 1348,
dropwise to the solution. The latter was submitted to 6 successive
45-s microwave irradiations at 160 W (pause time between 2
irradiation periods to return to 25 ꢀC). The mixture was diluted
with water, acidified with HCl (2 N), and extracted with ethyl
acetate. The organic layer was then concentrated to dryness
affording a brown residue, which was chromatographed on silica
gel (Hex/EtOAc 99:1 / 8:2) affording pure compounds 2 (106 mg,
0.16 mmol, 8%), 3 (116 mg, 0.22 mmol, 11%), 4 (16 mg, 0.03 mmol,
1.5%), 5 (8 mg, 0.02 mmol, 1%) and 6 (16 mg, 0.04 mmol, 2%).
1310, 1245, 1179, 1072; 1H NMR (400 MHz, CDCl3)
d 12.68 (1H, s),
7.88 (2H, dd, J ¼ 7.6, 1.5 Hz), 7.56e7.50 (3H, m), 6.68 (1H, s), 6.34
(1H, s), 6.24 (1H, s), 5.32 (1H, t, J ¼ 7.0 Hz), 5.06e5.03 (1H, m), 3.62
(2H, d, J ¼ 7.0 Hz), 2.13e2.06 (4H, m), 1.86 (3H, s), 1.65 (3H, s), 1.57
(3H, s); 13C NMR (100 MHz, CDCl3)
d 182.9, 163.7, 161.1, 160.3, 154.8,
139.2, 132.1, 131.7, 131.6, 129.1 (2C), 126.2 (2C), 123.6, 121.0, 105.7,
105.6, 105.2, 99.8, 39.6, 26.3, 25.6, 22.0, 17.6, 16.3; HRMS calcd for
C25H26O6 (Mþ þ Na) 413.1723, found 413.1733.
5.2.1. 6,8-Di-C-7-O-trigeranylchrysin (2)
5.3. Geranylated kaempherol derivatives (8e11)
IR (film, cmꢁ1): 2967, 2922, 2855, 1650, 1614, 1592, 1451, 1409,
1380, 1285, 1200, 1092, 848; 1H NMR (400 MHz, CDCl3)
d
12.80 (1H,
To a solution of 100 mg of kaempherol (0.35 mmol) in 1.0 mL of
methanol and 0.63 mL of 10% aqueous tetramethylammonium
hydroxide was added 89 mg of tetraethylammonium iodide
s), 7.89 (2H, dd, J ¼ 7.7, 1.3 Hz), 7.56e7.48 (3H, m), 6.71 (1H, s), 5.60
(1H, t, J ¼ 6.8 Hz), 5.28 (2H, m), 5.14e5.02 (3H, m), 4.40 (2H, d,
J ¼ 6.8 Hz), 3.61 (2H, d, J ¼ 5.9 Hz), 3.45 (2H, d, J ¼ 6.5 Hz), 2.15e1.99
(12H, m), 1.87 (3H, s), 1.83 (3H, s), 1.70 (3H, s), 1.68 (3H, s), 1.64 (3H,
s), 1.63 (3H, s), 1.58 (3H, s), 1.57 (3H, s), 1.54 (3H, s); 13C NMR
(0.35 mmol). After homogenization, 70
mL of geranyl bromide
(0.35 mmol) was added dropwise to the solution. The latter was
submitted to 7 successive 15-s microwave irradiations at 90 W
(pause time between 2 irradiation periods to return to 25 ꢀC). The
mixture was diluted with water, acidified with HCl (2 N), and
extracted with ethyl acetate. The organic layer was then concen-
trated to dryness affording a brown residue, which was chroma-
tographed on silica gel (Hex/EtOAc 95:5 / 1:1) affording pure
compounds 8 (2 mg, 0.003 mmol,1%), 9 (12 mg, 0.021 mmol, 6%),10
(9 mg, 0.021 mmol, 6%) and 11 (6 mg, 0.014 mmol, 4%).
(100 MHz, CDCl3)
d 183.3, 163.8, 161.5, 157.6, 153.4, 141.1, 135.8,
135.5, 131.8, 131.7, 131.6, 131.4, 131.2, 129.0 (2C), 126.3 (2C), 124.3,
124.0, 123.8, 123.0, 122.4, 119.8, 118.7, 113.6, 107.9, 105.5, 71.8, 39.8,
39.7, 39.6, 26.6, 26.3, 25.6 (3C), 23.0, 22.7, 17.7, 17.6 (2C), 16.5 (2C),
16.3; HRMS calcd for C45H58O4 (Mþ þ Na) 685.4227, found
685.4195.
5.2.2. 6-C-7-O-Digeranylchrysin (3)
IR (film, cmꢁ1): 2967, 2918, 1657, 1615, 1590, 1488, 1452, 1378,
5.3.1. 3,7-O-Digeranylkaempferol (8)
1350, 1311, 1174, 1106, 848, 769; 1H NMR (400 MHz, CDCl3)
d
12.77
IR (film, cmꢁ1): 3442, 1647, 1507, 1457, 1375, 1303, 1176; 1H NMR
(1H, s), 7.85 (2H, dd, J ¼ 7.7, 1.4 Hz), 7.58e7.48 (3H, m), 6.63 (1H, s),
6.48 (1H, s), 5.51 (1H, t, J ¼ 6.3 Hz), 5.25 (1H, t, J ¼ 7.2 Hz), 5.11e5.06
(2H, m), 4.62 (2H, d, J ¼ 6.3 Hz), 3.37 (2H, d, J ¼ 7.2 Hz), 2.16e1.95
(8H, m),1.82 (3H, s),1.79 (3H, s),1.67 (3H, s),1.64 (3H, s), 1.61 (3H, s),
(400 MHz, CDCl3)
d
12.81 (1H, s), 8.07 (2H, d, J ¼ 8.8 Hz), 6.99 (2H, d,
J ¼ 8.8 Hz), 6.41 (1H, s), 6.28 (1H, s), 5.90 (1H, s), 5.51 (1H, t,
J ¼ 6.8 Hz), 5.37 (1H, t, J ¼ 7.2 Hz), 5.12e5.07 (1H, m), 5.06e5.01 (1H,
m), 4.61e4.57 (4H, m), 2.12e2.05 (4H, m), 1.99e1.93 (4H, m), 1.76
(3H, s), 1.68 (3H, s), 1.65 (3H, s), 1.61 (3H, s), 1.59 (3H, s), 1.57 (3H, s);
1.58 (3H, s); 13C NMR (100 MHz, CDCl3)
d 182.3, 163.4, 162.7, 158.3,
156.1, 141.6, 135.1, 131.8, 131.5, 131.4, 131.1, 129.1 (2C), 126.1 (2C),
124.4, 123.6, 121.9, 118.8, 113.3, 105.8, 105.5, 90.5, 65.6, 39.8, 39.7,
26.7, 26.6, 25.6 (2C), 21.4, 17.6 (2C), 16.7, 16.1; HRMS calcd for
C35H42O4 (Mþ þ Na) 549.2975, found 549.2974.
13C NMR (100 MHz, CDCl3)
d 179.0, 162.7, 160.2, 156.7 (2C), 158.0,
142.5 (2C), 137.6, 131.9, 131.7, 130.3 (2C), 123.7 (2C), 123.0, 119.3,
118.9, 114.5 (2C), 105.7, 98.8, 93.7, 68.9, 65.0, 39.5 (2C), 26.2 (2C),
25.6 (2C), 17.6 (2C), 16.4 (2C); HRMS calcd for C35H42O6 (Mþ þ Na)
581.2874, found 581.2869.
5.2.3. 7-O-8-C-Digeranylchrysin (4)
IR (film, cmꢁ1): 2967, 2923, 1658, 1615, 1589, 1452, 1378, 1330,
5.3.2. 3-O-8-C-Digeranylkaempferol (9)
1274, 1171, 1106, 766; 1H NMR (400 MHz, CDCl3)
d
12.77 (1H, s), 7.90
IR (film, cmꢁ1): 3397, 2918, 2849, 1649, 1611, 1553, 1439, 1376,
(2H, dd, J ¼ 7.7, 1.5 Hz), 7.55e7.50 (3H, m), 6.66 (1H, s), 6.41 (1H, s),
5.49 (1H, t, J ¼ 6.4 Hz), 5.24 (1H, t, J ¼ 6.8 Hz), 5.10 (1H, t, J ¼ 5.0 Hz),
5.03 (1H, t, J ¼ 5.3 Hz), 4.63 (2H, d, J ¼ 6.4 Hz), 3.55 (2H, d,
J ¼ 6.8 Hz), 2.17e1.97 (8H, m), 1.80 (3H, s), 1.75 (3H, s), 1.68 (3H, s),
1.61 (3H, s), 1.60 (3H, s), 1.52 (3H, s); 13C NMR (100 MHz, CDCl3)
1265, 1214, 1176; 1H NMR (400 MHz, CDCl3)
d 12.71 (1H, s), 8.06
(2H, d, J ¼ 8.8 Hz), 6.94 (2H, d, J ¼ 8.8 Hz), 6.31 (1H, s), 6.19 (1H, s),
5.39 (1H, t, J ¼ 7.2 Hz), 5.29 (1H, t, J ¼ 7.0 Hz), 5.05e5.01 (2H, m),
4.60 (2H, d, J ¼ 7.2 Hz), 3.57 (2H, d, J ¼ 7.0 Hz), 2.11e2.08 (4H, m),
1.99e1.96 (4H, m), 1.83 (3H, s), 1.65 (3H, s), 1.59 (3H, s), 1.57 (3H, s),
d
182.9, 163.8, 162.4, 160.3, 154.5, 141.6, 135.4, 131.9, 131.8, 131.6,
1.56 (3H, s); 13C NMR (100 MHz, CDCl3)
d 179.4, 160.7, 160.1, 157.8,
131.4, 129.0 (2C), 126.2 (2C), 124.1, 123.6, 122.1, 118.8, 108.3, 105.3,
105.1, 96.2, 65.7, 39.7, 39.5, 26.7, 26.6, 25.6 (2C), 21.8, 17.6 (2C), 16.7,
16.1; HRMS calcd for C35H42O4 (Mþ þ Na) 549.2975, found
549.2983.
156.1, 153.8, 142.7, 139.1, 137.2, 132.1, 131.6, 130.5 (2C), 123.8, 123.6
(2C), 121.1, 119.3, 116.1 (2C), 105.9, 104.7, 99.3, 68.9, 39.6, 39.5, 26.4
(2C), 25.6 (2C), 21.8, 17.6 (2C), 16.4, 16.3; HRMS calcd for C35H42O6
(Mþ þ Na) 581.2874, found 581.2865.

P. Basabe et al. / European Journal of Medicinal Chemistry 45 (2010) 4258e4269
4265
5.3.3. 8-C-Geranylkaempferol: isomacarangin (10)
IR (film, cmꢁ1): 3388, 2918, 1648, 1608, 1561, 1509, 1438, 1374,
1315, 1241, 1176, 1114; 1H NMR (400 MHz, CDCl3)
11.74 (1H, s), 8.12
5.4.3. 8-C-Labda-8(17),13E-dienyl-4’-O-methylkaempferol (16)
22
[a
]
þ14.4 (c 0.09, CHCl3); IR (film, cmꢁ1): 3305, 2924, 2851,
D
d
1626, 1601, 1560, 1535, 1421, 1381, 1317, 1257, 1178, 1148, 1118, 1034;
(2H, d, J ¼ 8.9 Hz), 6.98 (2H, d, J ¼ 8.9 Hz), 6.61 (1H, s), 6.32 (1H, s),
6.14 (1H, s), 5.31 (1H, t, J ¼ 6.9 Hz), 5.08 (1H, s), 5.08e5.01 (1H, m),
3.62 (2H, d, J ¼ 6.9 Hz), 2.14e2.09 (4H, m), 1.85 (3H, s), 1.65 (3H, s),
1H NMR (400 MHz, CDCl3)
d
11.75 (1H, s), 8.17 (2H, d, J ¼ 9.0 Hz),
7.04 (2H, d, J ¼ 9.0 Hz), 6.59 (1H, s), 6.33 (1H, s), 5.97 (1H, s), 5.27
(1H, t, J ¼ 6.8 Hz), 4.80 (1H, s), 4.49 (1H, s), 3.89 (3H, s), 3.63 (2H, d,
J ¼ 6.8 Hz), 2.35 (1H, m), 2.20e0.97 (5H, m), 1.90 (1H, m), 1.86 (3H,
s), 1.72 (1H, m), 1.69 (1H, m), 1.55 (1H, m), 1.47 (1H, m), 1.37 (1H, m),
1.30 (1H, m), 1.13 (1H, m), 1.05 (1H, m), 0.92 (1H, m), 0.84 (3H, s),
1.57 (3H, s); 13C NMR (100 MHz, CDCl3)
d 175.5, 161.0, 159.0, 157.4,
153.8, 145.4, 139.4, 132.2, 132.1, 129.9 (2C), 123.6 (2C), 121.0, 115.7
(2C), 105.0, 103.8, 99.2, 39.6, 26.5, 25.6, 21.8, 17.6, 16.3; HRMS calcd
for C25H25O6 (Mþ) 421.1616, found 421.1642.
0.78 (3H, s), 0.65 (3H, s); 13C NMR (100 MHz, CDCl3)
d 175.2, 161.1,
160.8, 159.0, 153.8, 148.5, 145.4, 140.2, 135.4, 129.3 (2C), 123.5, 120.6,
114.1 (2C), 106.2, 105.0, 103.9, 99.1, 56.1, 55.5, 55.4, 42.1, 39.6, 39.0,
38.4, 38.2, 33.5 (2C), 24.4, 21.8, 21.7 (2C), 19.3, 16.5, 14.4; HRMS
calcd for C36H44O6 (Mþ þ Na) 595.3030, found 595.3027.
5.3.4. 3-O-Geranylkaempferol (11)
IR (film, cmꢁ1): 3365, 2966, 2926, 1652, 1607, 1507, 1448, 1361,
1283, 1259, 1207, 1175, 1087; 1H NMR (400 MHz, CDCl3)
d 12.77 (1H,
s), 8.04 (2H, d, J ¼ 8.5 Hz), 6.94 (2H, d, J ¼ 8.5 Hz), 6.41 (1H, s), 6.28
(1H, s), 6.10 (1H, s), 5.37 (1H, t, J ¼ 7.3 Hz), 5.15 (1H, s), 5.05e4.99
(1H, m), 4.58 (2H, d, J ¼ 7.3 Hz), 2.01e1.92 (4H, m), 1.65 (3H, s), 1.58
5.4.4. 3-O-Labda-8(17),13E-dienyl-4’-O-methylkaempferol (17)
22
[a
]
þ14.2 (c 0.26, CHCl3); IR (film, cmꢁ1): 3233, 2934, 2843,
D
(3H, s), 1.56 (3H, s); 13C NMR (100 MHz, CDCl3)
d
179.0, 162.3, 161.8,
1651, 1606, 1506, 1461, 1362, 1259, 1178,1033, 837; 1H NMR
157.9, 156.8, 156.5, 142.9, 137.3, 131.7, 130.6 (2C), 123.8, 123.2, 119.2,
115.4 (2C), 105.8, 98.9, 93.8, 68.9, 39.5, 26.2, 25.6, 17.6, 16.4; HRMS
calcd for C25H26O6 (Mþ þ Na) 445.1621, found 445.1608.
(400 MHz, CDCl3)
d
12.78 (1H, s), 8.10 (2H, d, J ¼ 8.8 Hz), 6.98 (2H, d,
J ¼ 8.8 Hz), 6.44 (1H, s), 6.31 (1H, s), 6.10 (1H, s), 5.34 (1H, t,
J ¼ 7.2 Hz), 4.77 (1H, s), 4.59 (2H, d, J ¼ 7.2 Hz), 4.39 (1H, s), 3.88 (3H,
s), 2.37 (1H, m), 2.05 (1H, m), 1.90 (1H, m), 1.86 (1H, m), 1.68 (1H,
m), 1.66 (1H, m), 1.60e1.30 (5H, m), 1.56 (3H, s), 1.52 (1H, m), 1.37
(1H, m), 1.13 (1H, m), 1.05 (1H, m), 0.97 (1H, m), 0.85 (3H, s), 0.78
5.4. Labdanyl 40-O-methylkaempferol derivatives (14e21)
A well-stirred mixture of 40-O-methylkaempferol (130 mg,
0.43 mmol), labdanyl bromide 12 (122 mg, 0.35 mmol), and
anhydrous potassium carbonate (18 mg, 0.13 mmol) in dry acetone
(0.60 mL) was refluxed for 3 h. The reaction mixture was filtered
and evaporated under pressure to give a residue that was purified
by column chromatography on silica gel (Hex/EtOAc, 98:2 / 9:1) to
afford compounds 14 (30 mg, 0.035 mmol, 10%), 15 (36 mg,
0.063 mmol, 18%), 16 (8 mg, 0.014 mmol, 4%) and 17 (24 mg,
0.042 mmol, 12%).
(3H, s), 0.63 (3H, s); 13C NMR (100 MHz, CDCl3)
d 179.1, 162.3, 162.2,
161.6, 156.8, 156.6, 148.5, 143.8, 137.2, 130.4 (2C), 123.1, 118.7, 113.8
(2C), 106.2, 105.7, 99.1, 93.9, 69.0, 56.4, 55.4, 55.3, 42.1, 39.6, 39.0,
38.4, 38.3, 33.5 (2C), 24.4, 21.8, 21.7, 19.3, 16.5, 14.4; HRMS calcd for
C36H44O6 (Mþ þ Na) 595.3030, found 595.3020.
5.5. Labdanyl kaempferol derivatives (18e21)
A well-stirred mixture of kaempferol (188 mg, 0.66 mmol),
labdanyl bromide 12 (186 mg, 0.53 mmol), and anhydrous potas-
sium carbonate (46 mg, 0.33 mmol) in dry acetone (0.80 mL) was
refluxed for 3 h. The reaction mixture was filtered and evaporated
under pressure to give a residue that was purified by column
chromatography on silica gel (Hex/EtOAc, 95:5 / 85:15) to afford
compounds 18 (41 mg, 0.047 mmol, 9%), 19 (57 mg, 0.102 mmol,
17%), 20 (15 mg, 0.026 mmol, 5%) and 21 (30 mg, 0.054 mmol, 10%).
5.4.1. 3,7-O-Di(labda-8(17),13E-dienyl)-4’-O-methylkaempferol (14)
22
[
a]
þ24.2 (c 1.49, CHCl3); IR (film, cmꢁ1): 3424, 2935, 1655,
D
1599, 1510, 1496, 1459, 1386, 1303, 1259, 1205, 1168, 1091, 835; 1H
NMR (400 MHz, CDCl3)
d
12.72 (1H, s), 8.10 (2H, d, J ¼ 8.4 Hz), 6.99
(2H, d, J ¼ 8.4 Hz), 6.43 (1H, s), 6.35 (1H, s), 5.44 (1H, t, J ¼ 6.3 Hz),
5.34 (1H, t, J ¼ 7.2 Hz), 4.83 (1H, s), 4.78 (1H, s), 4.62 (2H, d,
J ¼ 6.3 Hz), 4.60 (2H, d, J ¼ 7.2 Hz), 4.52 (1H, s), 4.40 (1H, s), 3.88
(3H, s), 2.35e0.90 (32H, m), 1.77 (3H, s), 1.57 (3H, s), 0.88 (6H, s),
0.79 (6H, s), 0.68 (3H, s), 0.64 (3H, s); 13C NMR (100 MHz, CDCl3)
5.5.1. 3,7-O-Di(labda-8(17),13E-dienyl)kaempferol (18)
22
[a
]
þ44.7 (c 0.16, CHCl3); IR (film, cmꢁ1): 3420, 2934, 1652,
D
d
179.0, 164.6, 162.0, 161.4, 156.7, 156.3, 148.5 (2C), 143.7, 143.0,
1491, 1384, 1287, 1206, 1170, 733; 1H NMR (400 MHz, CDCl3)
d 12.73
137.3, 130.2 (2C), 123.3, 118.9, 118.2, 113.8 (2C), 106.2 (2C), 105.8,
98.3, 92.7, 68.8, 65.4, 56.3, 56.1, 55.5 (2C), 55.3, 42.2, 42.1, 39.6 (2C),
39.1, 39.0, 38.4, 38.3 (3C), 33.5 (4C), 24.4 (2C), 21.8, 21.7 (2C), 21.5,
19.4 (2C), 16.8, 16.5, 14.5, 14.4; HRMS calcd for C56H76O6 (Mþ þ Na)
867.5534, found 867.5540.
(1H, s), 8.06 (2H, d, J ¼ 8.6 Hz), 6.96 (2H, d, J ¼ 8.6 Hz), 6.45 (1H, d,
J ¼ 2.2 Hz), 6.36 (1H, d, J ¼ 2.2 Hz), 6.15 (1H, s), 5.45 (1H, t,
J ¼ 7.0 Hz), 5.34 (1H, t, J ¼ 7.0 Hz), 4.82 (1H, s), 4.77 (1H, s), 4.60 (4H,
d, J ¼ 7.0 Hz), 4.51 (1H, s), 4.39 (1H, s), 2.35e0.90 (32H, m), 1.75 (3H,
s), 1.57 (3H, s), 0.85 (6H, s), 0.78 (6H, s), 0.67 (3H, s), 0.62 (3H, s); 13C
NMR (100 MHz, CDCl3)
d 179.1, 164.7, 161.8, 158.2, 156.7 (2C), 148.5
5.4.2. 7-O-Labda-8(17),13E-dienyl-4’-O-methylkaempferol (15)
(2C), 143.9, 143.2, 137.2, 130.6 (2C), 123.1, 118.7, 118.0, 115.5 (2C),
106.2 (2C), 105.7, 98.4, 92.8, 68.8, 65.5, 56.3, 56.0, 55.5, 55.4, 42.1
(2C), 39.6 (2C), 39.0 (2C), 38.4, 38.3 (3C), 33.5 (4C), 24.4 (2C), 21.7
(3C), 21.5, 19.4 (2C), 16.8, 16.5, 14.5, 14.4; HRMS calcd for C55H74O6
(Mþ þ Na) 853.5378, found 853.5383.
22
[
a
]
þ14.4 (c 0.39, CHCl3); IR (film, cmꢁ1): 3304, 2931, 1655,
D
1591, 1500, 1461, 1366, 1311, 1258, 1181, 1162, 1121, 1033; 1H NMR
(400 MHz, CDCl3)
d
11.72 (1H, s), 8.16 (2H, d, J ¼ 9.0 Hz),
7.03 (2H, d, J ¼ 9.0 Hz), 6.60 (1H, s), 6.49 (1H, d, J ¼ 2.2 Hz), 6.38
(1H, d, J ¼ 2.2 Hz), 5.46 (1H, t, J ¼ 6.6 Hz), 4.83 (1H, s), 4.61 (2H,
d, J ¼ 6.6 Hz), 4.52 (1H, s), 3.89 (3H, s), 2.35 (1H, m), 2.20 (1H,
m), 1.95 (1H, m), 1.87 (1H, m), 1.76 (3H, s), 1.75 (1H, m), 1.69 (1H,
m), 1.60e1.30 (5H, m), 1.56 (1H, m), 1.38 (1H, m), 1.15 (1H, m),
1.05 (1H, m), 0.98 (1H, m), 0.84 (3H, s), 0.79 (3H, s), 0.68 (3H, s);
5.5.2. 7-O-Labda-8(17),13E-dienylkaempferol (19)
22
[a
]
þ17.9 (c 2.55, CHCl3); IR (film, cmꢁ1): 3368, 2830, 1655,
D
1590, 1500, 1460, 1366, 1319, 1256, 1225, 1164, 1088, 1023; 1H NMR
(400 MHz, CDCl3)
d
11.73 (1H, s), 8.12 (2H, d, J ¼ 8.8 Hz), 7.36 (1H, s),
13C NMR (100 MHz, CDCl3)
d
175.1, 165.0, 161.1, 160.7, 156.7,
6.97 (2H, d, J ¼ 8.8 Hz), 6.61 (1H, s), 6.49 (1H, d, J ¼ 2.0 Hz), 6.38 (1H,
d, J ¼ 2.0 Hz), 5.46 (1H, t, J ¼ 6.4 Hz), 4.83 (1H, s), 4.61 (2H, d,
J ¼ 6.4 Hz), 4.51 (1H, s), 2.35 (1H, m), 2.20 (1H, m), 1.95 (1H, m), 1.87
(1H, m), 1.76 (3H, s), 1.75 (1H, m), 1.69 (1H, m), 1.60 (1H, m),
1.58e1.45 (3H, m), 1.56 (1H, m), 1.47 (1H, m), 1.38 (1H, m), 1.15 (1H,
148.5, 145.6, 143.1, 135.6, 129.3 (2C), 123.2, 118.1, 114.0 (2C), 106.2,
103.8, 98.4, 92.9, 65.5, 56.0, 55.4, 55.3, 42.2, 39.6, 39.1, 38.3 (2C),
33.5 (2C), 24.4, 21.8, 21.6, 19.4, 16.5, 14.5; HRMS calcd for
C36H44O6 (Mþ þ Na) 595.3030, found 595.3023.

4266
P. Basabe et al. / European Journal of Medicinal Chemistry 45 (2010) 4258e4269
m), 1.05 (1H, m), 0.98 (1H, m), 0.84 (3H, s), 0.79 (3H, s), 0.67 (3H, s);
13C NMR (100 MHz, CDCl3)
175.1, 165.0, 160.6, 157.3, 156.7, 148.5,
145.5, 143.2, 135.6, 129.6 (2C), 123.4, 118.0, 115.6 (2C), 106.2, 103.8,
98.4, 92.9, 65.5, 56.0, 55.5, 42.1, 39.6, 39.0, 38.3 (2C), 33.5 (2C), 24.4,
21.7, 21.5, 19.4, 16.8, 14.5; HRMS calcd for C35H42O6 (Mþ þ Na)
581.2874, found 581.2883.
acetone-d6) d 203.4, 168.2, 165.7, 164.7, 105.9, 96.6, 91.7, 56.1, 33.0;
d
HRMS calcd for C9H10O4 (Mþ þ Na) 205.0471, found 205.0479.
5.7. Prenyl cyclised phloroacetophenone derivatives (31e33)
A
well-stirred mixture of phloroacetophenone (100 mg,
0.54 mmol), 3,3-dimethylallyl bromide (0.05 mL mg, 0.43 mmol),
and anhydrous potassium carbonate (37 mg, 0.27 mmol) in dry
acetone (1.00 mL) was refluxed for 2 h. The reaction mixture was
filtered and evaporated under pressure to give a residue that was
purified by column chromatography on silica gel (Hex/EtOAc,
98:2 / 75:25) to afford compounds 31 (9 mg, 0.030 mmol, 5.5%),
32 (7 mg, 0.032 mmol, 6.0%), and 33 (29 mg, 0.121 mmol, 22.5%).
5.5.3. 8-C-Labda-8(17),13E-dienylkaempferol (20)
22
[a
]
þ12.0 (c 0.65, CHCl3); IR (film, cmꢁ1): 3369, 2926, 2848,
D
1707, 1652, 1607, 1561, 1513, 1441, 1370, 1259, 1151, 1133, 1047; 1H
NMR (200 MHz, CDCl3)
d
11.75 (1H, s), 8.13 (2H, d, J ¼ 8.8 Hz), 6.98
(2H, d, J ¼ 8.8 Hz), 6.61 (1H, s), 6.33 (1H, s), 6.20 (1H, s), 5.47 (1H, s),
5.23 (1H, t, J ¼ 7.0 Hz), 4.78 (1H, s), 4.47 (1H, s), 3.62 (2H, d,
J ¼ 7.0 Hz), 2.35e0.97 (16H, m),1.85 (3H, s), 0.85 (3H, s), 0.78 (3H, s),
0.64 (3H, s); 13C NMR (50.3 MHz, CDCl3)
d
175.7, 161.1, 159.2, 157.5,
5.7.1. Compound 31
154.1, 148.7, 145.6, 140.3, 135.7, 129.8 (2C), 124.0, 120.8, 115.9 (2C),
106.4, 105.3, 104.1, 99.4, 56.3, 55.7, 42.3, 39.8, 39.2, 38.7, 38.5, 33.8
(2C), 24.6, 22.0, 21.9 (2C), 19.6, 16.8, 14.7; HRMS calcd for C35H42O6
(Mþ þ Na) 581.2874, found 581.2903.
Mp: 103e105 ꢀC; IR (film, cmꢁ1): 3399, 2974, 2934, 2872, 1617,
1602, 1426, 1369, 1324, 1274, 1183, 1160, 1118, 1099, 1029; 1H NMR
(200 MHz, CDCl3)
2.53 (2H, t, J ¼ 6.9 Hz), 1.77 (2H, t, J ¼ 6.8 Hz), 1.75 (2H, t, J ¼ 6.9 Hz),
1.37 (6H, s), 1.33 (6H, s); 13C NMR (50.3 MHz, CDCl3)
203.1, 162.4,
d
14.10 (1H, s), 2.62 (3H, s), 2.61 (2H, t, J ¼ 6.8 Hz),
d
5.5.4. 3-O-Labda-8(17),13E-dienylkaempferol (21)
158.3, 154.5, 105.0, 100.2, 100.0, 75.7, 75.3, 33.2, 32.1, 31.7, 26.8 (4C),
16.4, 16.0; HRMS calcd for C18H24O4 (Mþ þ H) 305.1747, found
305.1754.
22
[a
]
þ12.2 (c 0.58, CHCl3); IR (film, cmꢁ1): 3421, 1653, 1608,
D
1507,1359,1174; 1H NMR (400 MHz, CDCl3)
d 12.78 (1H, s), 8.04 (2H,
d, J ¼ 8.3 Hz), 6.94 (2H, d, J ¼ 8.3 Hz), 6.43 (1H, s), 6.32 (1H, s), 6.12
(1H, m), 5.33 (1H, t, J ¼ 7.2 Hz), 4.76 (1H, s), 4.56 (2H, d, J ¼ 7.2 Hz),
4.38 (1H, s), 2.38e0.90 (16H, m), 1.55 (3H, s), 0.84 (3H, s), 0.77 (3H,
s), 0.61 (3H, s); 1H OH not observable. 13C NMR (50 MHz, CDCl3)
5.7.2. Compound 32
IR (film, cmꢁ1): 3338, 2970, 2937, 2873, 1619, 1430, 1365, 1290,
1253, 1192, 1156, 1117, 1082; 1H NMR (200 MHz, CDCl3)
d 13,78 (1H,
d
179.1, 162.3, 162.1, 158.1, 156.8 (2C), 148.2, 144.1, 137.1, 130.7 (2C),
s), 6.60 (1H, s), 5.75 (1H, s), 2.60 (3H, s), 2.57 (2H, t, J ¼ 6.6 Hz), 1.78
123.1, 118.6, 115.5 (2C), 106.2, 105.5, 99.1, 94.0, 69.0, 55.4 (2C), 42.1,
39.6, 39.0, 38.4, 38.3, 33.6 (2C), 24.4, 21.7 (2C),19.4,16.5,14.4; HRMS
calcd for C35H42O6 (Mþ þ Na) 581.2874, found 581.2883.
(2H, t, J ¼ 6.6 Hz), 1.32 (6H, s); 13C NMR (50.3 MHz, CDCl3)
d 203.5,
163.8, 160.8, 158.4, 104.5, 101.5, 95.7, 76.2, 32.9, 32.3, 26.9 (2C), 16.3;
HRMS calcd for C13H16O4 (Mþ þ Na) 259.0941, found 259.0939.
5.6. Methyl phloroacetophenone derivatives (28e30)
5.7.3. Compound 33
IR (film, cmꢁ1): 3404, 2975, 1618, 1501, 1430, 1412, 1367, 1330,
TMSCHN2 (2.0 M hexane solution) (7.5 mL, 15.0 mmol) was
added to a solution of phloroacetophenone (930 mg, 5.0 mmol) in
CHCl3 (10.0 mL)-MeOH (5.0 mL) under ice-cooling, and the whole
was stirred at room temperature for 14 h. AcOH (5 drops) was
added to the reaction mixture under ice-cooling, and the mixture
was stirred for 30 min and then concentrated. The residue was
chromatographed on silica gel (CHCl3-AcOEt (9:1)) to give 28
(87 mg, 0.44 mmol, 9%), 29 (438 mg, 2.41 mmol, 48%) as a pale
yellow solid and 30 (25 mg, 0.14 mmol, 3%).
1284, 1233, 1157, 1119, 1076; 1H NMR (200 MHz, CDCl3)
d 13.81 (1H,
s), 6.44 (1H, br s), 5.95 (1H, s), 2.62 (3H, s), 2.58 (2H, t, J ¼ 6.6 Hz),
1.79 (2H, t, J ¼ 6.6 Hz), 1.38 (6H, s); 13C NMR (50.3 MHz, CDCl3)
d
203.8, 165.0, 161.0, 157.8, 106.5, 99.8, 95.4, 76.3, 33.6, 31.7, 27.1
(2C), 16.5; HRMS calcd for C13H16O4 (Mþ þ Na) 259.0941, found
259.0940.
5.8. Prenyl phloroacetophenone derivatives (34e37)
A
well-stirred mixture of phloroacetophenone (500 mg,
5.6.1. 6-Hydroxy-2,4-dimethoxyacetophenone (28)
2.68 mmol), 3,3-dimethylallyl bromide (0.25 mL mg, 2.15 mmol),
and anhydrous potassium carbonate (326 mg, 2.36 mmol) in dry
acetone (5.00 mL) was refluxed for 4 h. The reaction mixture was
filtered and evaporated under pressure to give a residue that was
purified by column chromatography on silica gel (Hex/EtOAc,
95:5 / 8:2) to afford compounds 34 (38 mg, 0.125 mmol, 6.0%), 35
(10 mg, 0.042 mmol, 2.0%), 36 (3 mg, 0.013 mmol, 0.6%), and 37
(102 mg, 0.432 mmol, 20.0%).
Mp: 73e76 ꢀC; IR (film, cmꢁ1): 3398, 2941, 1622, 1592, 1458,
1423, 1364, 1271, 1219, 1159, 1117, 1079; 1H NMR (200 MHz, CDCl3)
d
14.03 (1H, s), 6.03 (1H, d, J ¼ 2.4 Hz), 5.90 (1H, d, J ¼ 2.4 Hz), 3.83
(3H, s), 3.80 (3H, s), 2.59 (3H, s); 13C NMR (50.3 MHz, CDCl3)
d
203.4,
167.8, 166.3, 163.1, 106.2, 93.6, 91.0, 55.8 (2C), 33.2; HRMS calcd for
C10H12O4 (Mþ þ H) 197.0808, found 197.0806.
5.6.2. 2,6-Dihydroxy-4-methoxyacetophenone (29)
Mp: 135e138 ꢀC; IR (film, cmꢁ1): 3134, 1635, 1570, 1560, 1492,
5.8.1. 2,4,6-Trihydroxy-3,5-di(3,3-dimethylallyl)acetophenone (34)
IR (film, cmꢁ1): 3388, 2971, 2916, 1613, 1435, 1366, 1322, 1299,
1478, 1460, 1400, 1283, 1262, 1212, 1167, 1111; 1H NMR (400 MHz,
acetone-d6)
d
11.68 (2H, s), 5.94 (2H, s), 3.75 (3H, s), 2.60 (3H, s); 13
C
1227, 1179, 1117, 1098, 1081; 1H NMR (200 MHz, CDCl3)
d
11.70 (2H,
s), 6.33 (1H, s), 5.22 (2H, t, J ¼ 7.4 Hz), 3.37 (4H, d, J ¼ 7.4 Hz), 2.65
(3H, s), 1.83 (6H, s), 1.78 (6H, s); 13C NMR (50.3 MHz, CDCl3)
204.0,
NMR (100 MHz, acetone-d6)
d 203.4, 166.3, 164.5 (2C), 105.3, 93.6
(2C), 55.1, 32.2; HRMS calcd for C9H10O4 (Mþ þ Na) 205.0471, found
d
205.0470.
159.7, 159.6 (2C), 136.7 (2C), 121.9 (2C), 105.5, 104.9 (2C), 33.3, 26.1
(2C), 22.0 (2C), 18.1 (2C); HRMS calcd for C18H24O4 (Mþ þ Na)
327.1567, found 327.1564.
5.6.3. 4,6-Dihydroxy-2-methoxyacetophenone (30)
mp: 157e159 ꢀC; IR (film, cmꢁ1): 3140, 1638, 1586, 1523, 1468,
1439, 1365, 1282, 1256, 1201, 1166, 1074; 1H NMR (200 MHz,
5.8.2. 2,6-Dihydroxy-4-(3,3-dimethylallyloxy)acetophenone (35)
Mp: 70e72 ꢀC; IR (film, cmꢁ1): 3305, 2971, 2925, 1630, 1587,
1519, 1433, 1366, 1286, 1253, 1165, 1087, 1070, 1026; 1H NMR
acetone-d6)
d
13.92 (1H, s), 9.38 (1H, s), 6.03 (1H, d, J ¼ 2.3 Hz), 5.94
(1H, d, J ¼ 2.3 Hz), 3.90 (3H, s), 2.55 (3H, s); 13C NMR (50.3 MHz,

P. Basabe et al. / European Journal of Medicinal Chemistry 45 (2010) 4258e4269
4267
(200 MHz, CDCl3)
J ¼ 6.6 Hz), 4.48 (2H, d, J ¼ 6.6 Hz), 2.67 (3H, s), 1.78 (3H, s), 1.72 (3H,
s); 13C NMR (50.3 MHz, CDCl3)
203.5, 165.3 (2C), 163.6, 139.4,
d
11.80 (82H, s), 5.93 (2H, s), 5.43 (1H, t,
chromatography on silica gel (Hex/EtOAc, 9:1) to afford compound
40 (45 mg, 0.120 mmol, 28.0%).
d
118.8, 105.3, 95.1 (2C), 65.3, 32.9, 26.0, 18.5; HRMS calcd for
5.10.1. Compound 40
C13H16O4 (Mþ þ Na) 259.0941, found 259.0954.
IR (film, cmꢁ1): 3336, 2931, 1617, 1499, 1429, 1366, 1330, 1278,
1160, 1075; 1H NMR (200 MHz, CDCl3)
d 13.90 (1H, s), 5.96 (1H, s),
5.8.3. 4,6-Dihydroxy-2-(3,3-dimethylallyloxy)acetophenone (36)
Mp: 105e107 ꢀC; IR (film, cmꢁ1): 3305, 2970, 2926, 1625, 1586,
1522, 1436, 1364, 1284, 1255, 1166, 1086, 1070, 1026; H NMR
5.18e4.99 (3H, m), 2.65e2.56 (2H, m), 2.63 (3H, s), 2.16e1.53 (10H,
m), 1.66 (3H, s), 1.58 (6H, s), 1.34 (3H, s); 13C NMR (50.3 MHz, CDCl3)
d
203.7, 165.0, 161.3, 157.8, 136.0, 131.7, 124.4, 123.7, 106.4, 100.2,
(200 MHz, CDCl3)
d
13.95 (1H, s), 5.96 (1H, d, J ¼ 2.2 Hz), 5.90 (1H, d,
95.4, 78.6, 39.9 (2C), 33.6, 29.6, 26.9, 26.0, 24.4, 22.7, 17.9, 16.3 (2C);
J ¼ 2.2 Hz), 5.50 (1H, t, J ¼ 6.6 Hz), 4.54 (2H, d, J ¼ 6.6 Hz), 2.61 (3H,
HRMS calcd for C23H32O4 (Mþ þ Na): 395.2193; found 395.2194.
s), 1.81 (3H, s), 1.75 (3H, s); 1H OH not observable. 13C NMR
(50.3 MHz, CDCl3)
d 203.4, 167.2, 163.0, 162.4, 138.8, 118.5, 106.3,
96.2, 91.3, 65.7, 33.2, 25.7, 18.2; HRMS calcd for C13H16O4 (Mþ þ Na)
5.11. Farnesyl phloroacetophenone derivatives (41e44)
259.0941, found 259.0949.
A
well-stirred mixture of phloroacetophenone (500 mg,
5.8.4. 2,4,6-Trihydroxy-3-(3,3-dimethylallyl)acetophenone (37)
Mp: 165e167 ꢀC; IR (film, cmꢁ1): 3266, 2965, 2922, 2728, 1631,
1442, 1403, 1367, 1283, 1171, 1151, 1075; 1H NMR (200 MHz,
2.68 mmol), farnesyl bromide (0.33 mL, 1.21 mmol), and anhydrous
potassium carbonate (326 mg, 2.36 mmol) in dry acetone (5.00 mL)
was refluxed for 4 h. The reaction mixture was filtered and evap-
orated under pressure to give a residue that was purified by column
chromatography on silica gel (Hex/EtOAc, 98:2 / 75:25) to afford
compounds 41 (15 mg, 0.026 mmol, 2.0%), 42 (28 mg, 0.075 mmol,
6.0%), 43 (22 mg, 0.059 mmol, 5.0%) and 44 (271 mg, 0.728 mmol,
60%).
acetone-d6)
5.21 (1H, t, J ¼ 7.0 Hz), 3.22 (2H, d, J ¼ 7.0 Hz), 2.60 (3H, s), 1.73 (3H,
s), 1.61 (3H, s); 13C NMR (50.3 MHz, acetone-d6)
203.1,164.3,162.2,
d 13.98 (1H, s), 9.50 (1H, s), 9.13 (1H, s), 6.06 (1H, s),
d
160.0, 130.1, 123.5, 107.1, 104.6, 94.2, 32.2, 25.3, 21.3, 17.2; HRMS
calcd for C13H16O4 (Mþ þ Na) 259.0941, found 259.0944.
5.9. Geranyl phloroacetophenone derivatives (38, 39)
5.11.1. 3-Farnesyl-6-farneloxy-6-hydroxyacetophenone (41)
IR (film, cmꢁ1): 3363, 2966, 2925, 1617, 1437, 1382, 1281, 1152,
The geranyl bromide (0.053 mL, 0.27 mmol) in THF (0.32 mL)
was slowly added to the phloroacetophenone (100 mg, 0.54 mmol)
in EtOH (1.75 mL) and 3.6 M NaOH (0.32 mL, 1.15 mmol). The
reaction is stirred at room temperature for 12 h. It was acidulated
with 2 M HCl and extracted three times with AcOEt. The combined
organic layers were washed with brine, dried over Na2SO4, filtered
and concentrated under pressure. The residue was purified by
column chromatography on silica gel (Bencene/EtOAc, 95:5)
affording compounds 38 (30 mg, 0.068 mmol, 25.0%), and 39
(33 mg, 0.108 mmol, 40.0%).
1096; 1H NMR (400 MHz, CDCl3)
d 12.30 (1H, s), 6.18 (1H, s), 5.90
(1H, s), 5.52 (1H, t, J ¼ 6.6 Hz), 5.27 (1H, t, J ¼ 7.2 Hz), 5.19e5.01 (4H,
m), 4.54 (2H, d, J ¼ 6.6 Hz), 3.38 (2H, d, J ¼ 7.2 Hz), 2.62 (3H, s),
2.13e1.97 (16H, m), 1.81 (3H, s), 1.73 (3H, s), 1.67 (6H, s), 1.59 (12H,
s); 13C NMR (100 MHz, CDCl3)
d 203.3, 164.4, 161.9, 161.0, 141.8,
139.5, 135.7, 135.6,131.3, 131.2,124.6, 124.4, 124.2, 123.5,121.7,118.6,
105.9, 105.7, 91.5, 65.4, 39.6 (3C), 39.4, 33.0, 26.6 (2C), 26.2 (2C),
25.6 (2C), 21.4, 17.6 (2C), 16.6, 16.2, 15.9 (2C); HRMS calcd for
C38H56O4 (Mþ þ Na) 599.4071, found 599.4068.
5.11.2. 4-Farnesyloxy-2,6-dihydroxyacetophenone (42)
5.9.1. 3,5-Digeranyl-2,4,6-trihydroxyacetophenone (38)
IR (film, cmꢁ1): 3363, 2966, 2925, 1617, 1437, 1382, 1281, 1152,
IR (film, cmꢁ1): 3388, 2966, 2923, 2854, 1612, 1432, 1366, 1300,
1096; 1H NMR (200 MHz, CDCl3)
d 12.10 (2H, s), 5.94 (2H, s), 5.43
1262, 1164, 1114, 1086; 1H NMR (200 MHz, CDCl3)
d
12.10 (2H, s),
(1H, t, J ¼ 6.2 Hz), 5.13e5.02 (2H, m), 4.51 (2H, d, J ¼ 6.2 Hz), 2.67
6.35 (1H, s), 5.22 (2H, t, J ¼ 7.2 Hz), 5.09e4.99 (2H, m), 3.38 (4H, d,
(3H, s), 2.10e1.93 (8H, m), 1.72 (3H, s), 1.68 (3H, s), 1.59 (6H, s); 13C
J ¼ 7.2 Hz), 2.65 (3H, s), 2.09 (8H, s), 1.81 (6H, s), 1.67 (6H, s), 1.59
NMR (50.3 MHz, CDCl3) d 203.6, 165.4 (2C), 163.7, 142.4, 135.8, 131.6,
(6H, s); 13C NMR (50.3 MHz, CDCl3)
d
202.8, 158.8, 158.5 (2C), 139.3
124.5, 123.8, 118.7, 105.3, 95.0 (2C), 65.4, 39.9, 39.8, 32.9, 26.9, 26.4,
25.9, 17.9, 16.4, 16.3; HRMS calcd for C23H32O4 (Mþ þ Na) 395.2193,
found 395.2211.
(2C), 131.3 (2C), 122.5 (2C), 120.7 (2C), 104.3, 103.7 (2C), 38.7 (2C),
32.2, 25.2 (2C), 24.8 (2C), 20.7 (2C), 16.8 (2C), 15.2 (2C); HRMS calcd
for C28H40O4 (Mþ þ Na) 463.2819, found 463.2836.
5.11.3. 2-Farnesyloxy-4,6-dihydroxyacetophenone (43)
5.9.2. 3-Geranyl-2,4,6-trihydroxyacetophenone (39)
IR (film, cmꢁ1): 3134, 2964, 2927, 1624, 1550, 1491, 1463, 1373,
IR (film, cmꢁ1): 3349, 2967, 2924, 2850, 1630, 1513, 1440, 1366,
1288, 1258, 1213, 1166, 1104, 1072; 1H NMR (400 MHz, CDCl3)
1292, 1150, 1071; 1H NMR (200 MHz, CDCl3)
d
11.90 (2H, s), 6.85
d
13.98 (1H, s), 5.97 (1H, d, J ¼ 2.2 Hz), 5.90 (1H, d, J ¼ 2.2 Hz), 5.65
(1H, br s), 5.87 (1H, s), 5.23 (1H, t, J ¼ 7.4 Hz), 5.05e4.98 (1H, m),
(1H, s), 5.50 (1H, t, J ¼ 6.6 Hz), 5.18e5.02 (2H, m), 4.57 (2H, d,
J ¼ 6.6 Hz), 2.62 (3H, s), 2.16e1.96 (8H, m), 1.74 (3H, s), 1.68 (3H, s),
3.34 (2H, d, J ¼ 7.4 Hz), 2.66 (3H, s), 2.07 (4H, s), 1.79 (3H, s), 1.66
(3H, s), 1.58 (3H, s); 13C NMR (50.3 MHz, CDCl3)
d
204.1, 162.7, 161.7
1.61 (3H, s), 1.60 (3H, s); 13C NMR (50.3 MHz, CDCl3)
d 203.6, 167.4,
(2C), 140.0, 132.4, 123.8, 121.8, 105.7, 105.4, 95.5, 39.9, 33.1, 26.5,
26.0, 21.7, 17.9, 16.5; HRMS calcd for C18H24O4 (Mþ þ Na) 327.1567,
found 327.1571.
163.4, 163.3, 142.4, 135.8, 131.6, 124.5, 123.7, 118.6, 106.3, 96.5, 91.8,
65.9, 39.9, 39.7, 33.3, 26.9, 26.4, 25.9, 17.9, 16.9, 16.3; HRMS calcd for
C23H32O4 (Mþ þ Na) 395.2193, found 395.2179.
5.10. Farnesyl cyclised phloroacetophenone derivative (40)
5.11.4. 3-Farnesyl-2,4,6-trihydroxyacetophenone (44)
Mp: 74e77 ꢀC; IR (film, cmꢁ1): 3346, 2968, 2925, 1629, 1509,
A
well-stirred mixture of phloroacetophenone (100 mg,
1438, 1401, 1366, 1291, 1150, 1080; H NMR (200 MHz, CDCl3) d 12.10
0.54 mmol), farnesyl bromide (0.12 mL, 0.43 mmol), and anhydrous
potassium carbonate (54 mg, 0.40 mmol) in dry acetone (1.00 mL)
was refluxed for 2 h. The reaction mixture was filtered and evap-
orated under pressure to give a residue that was purified by column
(2H, s), 6.16 (1H, s), 5.85 (1H, s), 5.26 (1H, t, J ¼ 7.0 Hz), 5.13e5.03
(2H, m), 3.37 (2H, d, J ¼ 7.0 Hz), 2.66 (3H, s), 2.10e1.96 (8H, m), 1.82
(3H, s), 1.67 (3H, s), 1.59 (6H, s); 13C NMR (50.3 MHz, CDCl3)
d 204.6,
163.1, 162.4, 161.0, 138.1, 135.5, 131.4, 124.6, 124.1, 122.2, 106.6, 105.2,

4268
P. Basabe et al. / European Journal of Medicinal Chemistry 45 (2010) 4258e4269
95.4, 39.9 (2C), 32.8, 26.9, 26.7, 25.9, 21.6, 17.9, 16.4, 16.2; HRMS
163.7, 130.3, 130.0, 105.1, 94.9 (2C), 68.6, 33.0, 32.2, 29.9, 29.8, 29.7,
29.6, 29.5 (2C), 29.2 (3C), 27.5 (2C), 26.1, 22.9, 14.4; HRMS calcd for
C
calcd for C23H32O4 (Mþ þ Na) 395.2193, found 395.2178.
26H42O4 (Mþ þ Na) 441.2975, found 441.2956.
5.12. Bromides 46
5.14.3. 4,6-Dihydroxy-2-oleylacetophenone (51)
To a solution of oleyl alcohol (1.58 mL, 5.0 mmol) in DCM
(30.0 mL) was added CBr4 (2.072 g, 6.25 mmol) and PPh3 (2.190 g,
8.35 mmol) in portions at 0 ꢀC. After 10 min, it was diluted with
hexane and filtered through CeliteÔ. It was evaporated under
pressure and added hexane to the residue in order to precipitate
the PPh3 (3 times) affording compound 46 (1.64 g, 4.95 mmol, 99%).
IR (film, cmꢁ1): 3423, 2924, 2854, 1630, 1464, 1298, 1284, 1163,
1109; 1H NMR (200 MHz, CDCl3)
d 13.98 (1H, s), 5.96 (1H, d,
J ¼ 2.2 Hz), 5.90 (1H, d, J ¼ 2.2 Hz), 5.88 (1H, s), 5.42e5.28 (2H, m),
3.98 (2H, t, J ¼ 6.4 Hz), 2.63 (3H, s), 2.05e1.95 (4H, m), 1.90e1.87
(2H, m), 1.40e1.15 (22H, m), 0.95e0.83 (3H, m); 13C NMR
(50.3 MHz, CDCl3)
d 203.5, 167.4, 163.5, 163.0, 130.3, 130.0, 106.3,
96.4, 91.4, 69.3, 33.4, 32.1, 30.0, 29.9, 29.8, 29.6, 29.4 (3C), 29.2 (3C),
27.4, 26.5, 22.9, 14.3; HRMS calcd for C26H42O4 (Mþ þ Na) 441.2975,
found 441.2972.
5.12.1. 1-Bromooctadec-9Z-ene (46)
IR (film, cmꢁ1): 3004, 2923, 2854, 1465, 1438, 1377, 1250, 1206,
1119; 1H NMR (200 MHz, CDCl3)
d 5.41e5.28 (2H, m), 3.40 (2H, t,
J ¼ 7.0 Hz), 2.08e1.97 (4H, m), 1.85 (2H, q, J ¼ 7.0 Hz), 1.41e1.27
5.14.4. 2,4,6-Trihydroxy-3-oleylacetophenone (52)
(22H, m), 0.88 (3H, t, J ¼ 6.6 Hz); 13C NMR (50.3 MHz, CDCl3)
IR (film, cmꢁ1): 3319, 2926, 2854, 1707, 1619, 1437, 1401, 1365,
d
129.5, 129.3, 33.3, 32.5, 31.5, 29.4, 29.3, 29.2 (4C), 29.0, 28.8, 28.4,
1290, 1153, 1128, 1080; 1H NMR (200 MHz, CDCl3)
d 13.60 (2H, s),
27.8, 26.8, 22.3, 13.7.
6.14 (1H, s), 5.87 (1H, s), 5.42e5.38 (2H, m), 2.67 (3H, s), 2.52 (2H, t,
J ¼ 7.0 Hz), 2.03e1.92 (4H, m), 1.60e1.42 (2H, m), 1.39e1.19 (22H,
5.13. Bromides 48
m), 0.98e0.80 (3H, m); 13C NMR (50.3 MHz, CDCl3)
d 203.8, 163.9,
161.0, 159.7, 130.2 (2C), 108.1, 105.2, 94.8, 33.0, 32.8, 32.1, 30.0, 29.8,
29.5, 29.4, 29.3 (3C), 29.1 (3C), 27.4, 22.9, 22.5, 14.4; HRMS calcd for
C26H42O4 (Mþ þ Na) 441.2975, found 441.2960.
To a solution of octadecanol (1.0 g, 3.70 mmol) in DCM (23.0 mL)
was added CBr4 (1.53 g, 4.62 mmol) and PPh3 (1.62 g, 6.20 mmol) in
portions at 0 ꢀC. After 10 min, it was diluted with hexane and
filtered through CeliteÔ. It was evaporated under pressure and
added hexane to the residue in order to precipitate the PPh3 (3
times) affording compound 48 (1.19 g, 3.58 mmol, 97%).
5.15. Stearyl phloroacetophenone derivatives (53e55)
A
well-stirred mixture of phloroacetophenone (300 mg,
1.61 mmol), bromide 48 (428 mg, 1.29 mmol), and anhydrous
potassium carbonate (111 mg, 0.81 mmol) in dry acetone (3.00 mL)
was refluxed for 3 h. The reaction mixture was filtered and evap-
orated under pressure to give a residue that was purified by column
chromatography on silica gel (Hex/EtOAc, 100:0 / 75:25) to afford
compounds 53 (19 mg, 0.046 mmol, 3.6%), 54 (16 mg, 0.039 mmol,
3.0%) and 55 (10 mg, 0.024 mmol, 1.8%).
5.13.1. 1-Bromooctadecane (48)
IR (film, cmꢁ1): 2917, 2851, 1466, 1377, 1252, 1119; 1H NMR
(200 MHz, CDCl3)
d
3.41 (2H, t, J ¼ 7.0 Hz), 1.85 (2H, q, J ¼ 7.0 Hz),
1.46e1.37 (2H, m), 1.25 (26H, s), 0.88 (3H, t, J ¼ 6.6 Hz); 13C NMR
(50.3 MHz, CDCl3)
22.3, 13.7.
d 33.3, 32.4, 31.5, 29.3 (10C), 29.2, 28.4, 27.8,
5.14. Oleyl phloroacetophenone derivatives (49e55)
5.15.1. 2,6-Dihydroxy-4-stearyloxyacetophenone (53)
Mp: 94e96 ꢀC; IR (film, cmꢁ1): 3363, 2919, 2848, 1647, 1636,
1586, 1559, 1522, 1458, 1437, 1364, 1287, 1217, 1178, 1070; H NMR
A
well-stirred mixture of phloroacetophenone (500 mg,
2.68 mmol), bromide 46 (710 mg, 2.14 mmol), and anhydrous
potassium carbonate (185 mg, 1.34 mmol) in dry acetone (3.00 mL)
was refluxed for 9 h. The reaction mixture was filtered and evap-
orated under pressure to give a residue that was purified by column
chromatography on silica gel (Hex/EtOAc, 100:0 / 7:3) to afford
compounds 49 (18 mg, 0.027 mmol, 1.3%), 50 (58 mg, 0.139 mmol,
6.5%), 51 (22 mg, 0.052 mmol, 2.5%) and 52 (28 mg, 0.068 mmol,
3.2%).
(200 MHz, CDCl3)
d
13.30 (2H, s), 5.93 (2H, s), 3.93 (2H, t, J ¼ 6.2 Hz),
2.67 (3H, s), 1.78e1.67 (2H, m), 1.45e1.15 (30H, m), 0.93e0.82 (3H,
m); 13C NMR (50.3 MHz, CDCl3): 203.6, 165.6, 163.7, 105.2, 94.9 (2C),
68.6, 32.9, 32.2, 29.9 (13C), 29.2, 26.2, 22.9, 14.4; HRMS calcd for
C26H44O4 (Mþ þ Na) 443.3132, found 443.3135.
5.15.2. 4,6-Dihydroxy-2-stearyloxyacetophenone (54)
Mp: 91e93 ꢀC; IR (film, cmꢁ1): 3151, 2917, 2850, 1627, 1559,
1489, 1464, 1367, 1285, 1258, 1209, 1164, 1105, 1071, 1027; H NMR
5.14.1. 6-Hydroxy-2,4-dioleylacetophenone (49)
(200 MHz, acetone-d6) d 13.96 (1H, s), 9.42 (1H, s), 6.01 (1H, d,
IR (film, cmꢁ1): 2924, 2853, 1620, 1596, 1466, 1432, 1364, 1271,
J ¼ 2.0 Hz), 5.93 (1H, d, J ¼ 2.0 Hz), 4.07 (2H, t, J ¼ 6.4 Hz), 2.63
1214, 1174, 1111, 1078; 1H NMR (200 MHz, CDCl3)
d 14.06 (1H, s),
(3H, s), 1.98e1.82 (2H, m), 1.62e1.45 (2H, m), 1.28 (28H, s),
6.02 (1H, s), 5.89 (1H, s), 5.41e5.26 (4H, m), 4.10e3.90 (4H, m), 2.63
(3H, s), 2.04e1.96 (8H, m), 1.86e1.70 (4H, m), 1.40e1.15 (47H, m),
0.95e1.83 (3H, m); 13C NMR (50.3 MHz, acetone-d6)
d 202.7, 167.7,
165.1, 163.5, 105.4, 95.9, 91.7, 69.1, 32.6, 32.0, 29.7 (12C), 29.5,
26.5, 22.9, 14.3; HRMS calcd for C26H44O4 (Mþ þ Na) 443.3132,
found 443.3137.
0.88 (3H, m); 13C NMR (50.3 MHz, CDCl3)
d 203.2, 167.8,165.9, 162.6,
130.3 (2C), 130.0 (2C), 106.1, 94.0, 91.8, 69.1, 68.5, 33.3, 32.8, 32.1,
30.0, 29.8, 29.7, 29.6, 29.4 (8C), 29.3 (2C), 29.2 (8C), 27.4, 26.5, 26.2,
22.9,14.3 (2C); HRMS calcd for C44H76O4 (Mþ þ Na) 691.5636, found
691.5630.
5.15.3. 2,4,6-Trihydroxy-3-stearylacetophenone (55)
Mp: 83e86 ꢀC; IR (film, cmꢁ1): 3317, 2923, 2853, 1618, 1438,
1366, 1291, 1126, 1152, 1080; H NMR (200 MHz, methanol-d6)
5.14.2. 2,6-Dihydroxy-4-oleylacetophenone (50)
d
13.40 (2H, s), 5.88 (1H, s), 2.59 (3H, s), 2.48 (2H, t, J ¼ 7.7 Hz),
IR (film, cmꢁ1): 3420, 2924, 2854, 1635, 1587, 1527, 1458, 1365,
1.48e1.15 (32H, m), 0.94e0.83 (3H, m); 1H OH not observable.
13C NMR (50.3 MHz, methanol-d4): 203.4, 163.7, 162.9, 160.5,
107.6 (2C), 93.5, 31.9 (2C), 31.7, 29.6 (11C), 29.5, 28.9, 22.6, 21.8,
13.3; HRMS calcd for C26H44O4 (Mþ þ Na) 443.3132, found
443.3138.
1298, 1258, 1170, 1071; 1H NMR (200 MHz, CDCl3)
d 13.20 (2H, s),
5.92 (2H, s), 5.42e5.30 (2H, m), 3.92 (2H, t, J ¼ 7.0 Hz), 2.68 (3H, s),
2.08e1.91 (4H, m), 1.80e1.65 (2H, m), 1.40e1.15 (22H, m),
0.95e0.82 (3H, m); 13C NMR (50.3 MHz, CDCl3)
d 203.4, 165.5 (2C),

P. Basabe et al. / European Journal of Medicinal Chemistry 45 (2010) 4258e4269
4269
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Acknowledgements
The authors are grateful to Dr. A. M. Lithgow and Dr. C. Raposo
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