Synthesis, biological evaluation and quantitative structure-activities relationship of flavonoids as vasorelaxant agents

Article abstract of DOI:10.1016/j.bmc.2008.11.052

A series of flavonoid derivatives were designed, synthesized. Their vasorelaxant activities were evaluated experimentally against rat aorta rings pretreated with phenylephrine (PE). Among them, 6-hydroxy-8-allyl-4′-chloro-flavanone 8q exhibited the highes

Full text of DOI:10.1016/j.bmc.2008.11.052

Bioorganic & Medicinal Chemistry 17 (2009) 716–726
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Synthesis, biological evaluation and quantitative structure-activities
relationship of flavonoids as vasorelaxant agents
*
Xiaowu Dong, Tao Liu, Jingying Yan, Peng Wu, Jing Chen, Yongzhou Hu
ZJU-ENS Joint Laboratory of Medicinal Chemistry, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of flavonoid derivatives were designed, synthesized. Their vasorelaxant activities were evaluated
experimentally against rat aorta rings pretreated with phenylephrine (PE). Among them, 6-hydroxy-8-
Received 23 September 2008
Revised 15 November 2008
Accepted 18 November 2008
Available online 24 November 2008
allyl-40-chloro-flavanone 8q exhibited the highest vasodilatory activity (EC50 = 4.6
lM, Emax = 95.1%).
The 3D-QSAR analysis was carried out by comparative molecular field analysis (CoMFA) method, and a
statistically reliable model with good predictive power (r2 = 0.872 and qc2v = 0.496) was established.
The contour plots of CoMFA model provide a good insight into the structure-activity relationships of
these compounds and may be used to design more potent flavonoids derivatives as vasorelaxant agents.
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords:
Flavonoids
Vasorelaxant activities
CoMFA
3D-QSAR
1. Introduction
In our previous studies, some quercetin derivatives (or analogs)
were prepared, and their vasodilatory activities had positive corre-
Flavonoids, important components of a variety of traditional
Chinese medicines and phytomedicines, are compounds bearing a
C6–C3–C6 skeleton with diverse pharmacological properties, such
as anticancer, antioxidant, anti-aging and antibacterial effect.1–3
And their cardiovascular protective effects have been reported re-
cently.4,5 The epidemiological reports demonstrated that people
can lower incidence of heart diseases if they have a high dietary in-
take of flavonoids.6,7 As we know, one of the main reasons in car-
diovascular diseases is involvement of increasing tonicity or
losing relaxation capacity of vascular tissues. Many studies have
demonstrated some flavonoids produced concentration-dependent
relaxation responses on isolated aorta rings and antihypertensive
effect on animal models.8–10 The relaxation is in part mediated
by stimulation of nitric oxide released from the endothelium, while
the majority of the relaxation is attributed to direct action of the
flavonoids on the vascular smooth.11–13 Although structure-activ-
ity relationships (SAR) studies of flavonoids are hampered by their
structural diversity and different effect mechanisms, several
structural features have been found to be involved in the endothe-
lium-dependent vasodilatory activity:9,10 (1) 4-carbonyl group is
required as well as the double bond between C2–C3; (2) the pattern
of hydroxylation in B-ring is important for the activity, (3) the
presence of glycosylation group greatly reduce relaxation effect.
lation with their log P values. Among them, 5,7-dihydroxy-30-bro-
mo-flavone exhibited the highest vasodilatory activity.14 These
prompted us to design a novel series of lipophilic flavonoid deriv-
atives in attempt to improve vasodilatory activity. In the course of
an analog generation program, introduction of allyl group as well
as decreasing the number of hydroxyl groups in A-ring were taken
into consideration, and the effect of structural skeletons (chalcone,
flavanone, flavone and aurone) and substituents on B-ring on
vasodilatory activities were also investigated. According to the
analyses above, in present paper, we described the synthesis of a
series of flavonoids derivatives, and the evaluation of these com-
pounds as vasorelaxant agents. In addition, a comparative molecu-
lar field analysis (CoMFA) was performed to probe the quantitative
structure-activity relationships (QSAR) of these compounds.
2. Results and discussion
2.1. Chemistry
The synthetic route of compounds 7–10 is illustrated in Scheme
1. Acetophenone 1 was treated with chloromethoxymethyl ether
and potassium carbonate in acetone at room temperature to pro-
duce compounds 2, which were allylated by allyl bromide and suc-
cessively heated at 220 °C to afford Claisen rearrange products 3.
Intermediates 4 were prepared by Claisen–Schmidt condensation
of 2 or 3 with appropriate aromatic aldehyde. Flavanones 5 were
obtained by cyclization of 2-hydroxy-chalcones 4 in a solution of
* Corresponding author. Tel./fax: +86 571 88208460.
E-mail address: huyz@zjuem.zju.edu.cn (Y. Hu).
0968-0896/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2008.11.052

X. Dong et al. / Bioorg. Med. Chem. 17 (2009) 716–726
717
Scheme 1. Synthesis of flavonoids 7a–b, 7j–l, 7o, 8a–q, 9a–b, 10a, 10c and 10o. Reagents and conditions: (a) MOMCl, K2CO3, acetone 0 °C to rt.; (b) Allyl bromide, K2CO3,
DMF, 100 °C; (c) 220 °C, N,N-dimethylaniline, N2; (d) appropriate benzaldehyde, 10% KOH, Ethanol/H2O, rt; (e): NaOAc, EtOH, reflux; (f): Hg(OAc)2, pyridine, 60 °C (g): 5% HCl,
MeOH/THF (1/1, v/v), reflux; (h) I2, pyridine, 90 °C.
NaOAc in ethanol at 80 °C, while aurones 6 were obtained by reac-
tion of 4 in a solution of Hg(OAc)2 in pyridine at 60 °C, respectively.
Demethoxymethylation of 4, 5 and 6 were carried out in 5% HCl
MeOH/THF (1/4, v/v) at reflux temperature to afford compounds
7, 8 and 9 in good yield, respectively. Finally, flavones 10 were ob-
tained by dehydrogenation of the corresponding flavanones 8 in
presence of iodine and pyridine. Structures of all synthesized com-
pounds were elucidated by 1H NMR and ESI-MS.
vasodilators are the compounds whose EC50 values are more than
100 M and Emax values are limited (less than 70%).
As shown in Table 1, chalcone and flavanone derivatives
showed higher activities than flavone and aurone derivatives bear-
ing same substituents (7a, 8a > 10a > 9a; 7b, 8b > 9b).
Though the result of our previous studies showed that flavo-
noids had higher activity with the augment of log P values,14 unfor-
tunately, it was observed that the vasodilatory activity of
flavonoids was not just connected with lipophilicity when allyl
group was introduced and the number of hydroxyl groups in A-ring
was decreased in present studies. For example, Compound 8e bear-
ing 8-allyl group (more lipophilic), exhibited weaker activity than
that of compound 8a without allyl group (less lipophilic). However,
6-hydroxy-8-allyl-40-chloro-flavanone 8q exhibited the highest
l
2.2. Vasorelaxation activity and SAR
Vasodilatory activity was evaluated in aortic rings with endo-
thelium pre-contracted with 1 lM phenylephrine (PE). Quercetin,
a well known vasodilator, was used as the positive control. All
the tested compounds promoted relaxation in a dose-dependent
manner and their maximal effects was observed at 300 lM.
According to their ability to induce vasorelaxation (Table 1 and
Fig. 1), tested compounds are classified into three categories based
on their potency (EC50) and efficacy (Emax). Compounds inducing
50% relaxation at small concentration (less than 50 lM) with good
efficacy (more than 90%) are considered to be good relaxing agents,
and the compounds inducing moderate Emax (70–90%) with low
EC50 values (less than 100 lM) are moderate relaxing agents. Weak
vasodilatory activity (EC50 = 4.6
potent than compound of 8d without of allyl group
(EC50 = 38.5 M, Emax = 91.8%). In allylated flavonoid derivatives,
the effects on vasodilatory activities of different substituents of
flavonoids were further investigated. Hydroxyl substituent on B-
ring could significantly increase the vasorelaxant activity (7j,
7l > 7k; 8i, 8j > 8e–h) when they were bearing hydroxyl group on
C-5 position of A-ring. But it did not seem to have any effect of hy-
droxyl group on B-ring for the flavonoids without hydroxyl group
lM, Emax = 95.1%), and it is more
l

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X. Dong et al. / Bioorg. Med. Chem. 17 (2009) 716–726
Table 1
Structure and vasorelaxant activities of tested flavonoids
No.
R5
R6
EC50 (10
l
M)
pEC50
Emax
Activity classb
ComFA model
Pred. pEC50
Res.
Quercetin
7a
7b
/
/
24.4
2.13
2.25
2.40
N.D.c
8.91
N.D.c
4.24
2.01
3.85
N.D.c
N.D.c
N.D.c
N.D.c
3.70
3.21
0.94
2.69
N.D.c
14.2
3.45
1.02
0.46
N.D.c
22.0
3.68
8.17
5.13
3.61
4.67
4.65
4.62
/
4.05
/
4.36
4.70
4.42
/
91.3
99.8
104.1
108.1
71.8
73.4
59.8
93.5
97.2
91.8
78.8
76.7
77.6
81.0
97.8
9.86
96.6
87.2
85.0
70.8
95.3
90.2
95.1
59.2
58.4
84.3
82.1
67.3
++
+++
+++
+++
+
++
+
+++
+++
+++
+
/
/
4,6-DiOH
4,6-DiOH
30-Br
4.70
4.69
4.52
/
4.19
/
4.38
4.75
4.70
/
0.03
0.04
ꢀ0.10
/
0.14
/
0.02
0.05
0.28
/
30,40-OCH2O-
40-OH
7j
3-Allyl-4,6-diOH
3-Allyl-4-OH
3-Allyl-4-OH
3-Allyl-5-OH
5,7-DiOH
7k
30,40-OCH2O–
40-OH
7la
7o
40-OH
30-Br
8a
8b
8d
8e
8f
8g
8h
8i
8j
8k
8l
8m
8n
8oa
8p
8q
9a
5,7-DiOH
6-OH
30,40-OCH2O–
30-Br
5,7-DiOH-8-Allyl
5,7-DiOH-8-Allyl
5,7-DiOH-8-Allyl
5,7-DiOH-8-Allyl
5,7-DiOH-8-Allyl
5,7-DiOH-8-Allyl
7-OH-8-Allyl
7-OH-8-Allyl
7-OH-8-Allyl
7-OH-8-Allyl
6-OH-8-Allyl
6-OH-8-Allyl
6-OH-8-Allyl
H
30-Br
30-Cl
/
/
/
+
+
+
/
/
/
/
/
/
40-Cl
40-OMe
30-OH
4.44
4.49
5.03
4.57
/
3.84
4.47
4.99
5.33
/
+++
+++
+++
++
+
+++
+++
+++
+++
+
4.68
4.57
4.88
4.58
/
3.78
4.66
4.89
4.97
/
0.24
0.08
ꢀ0.15
0.01
/
ꢀ0.06
0.19
ꢀ0.10
ꢀ0.36
/
40-OH
30,40-OCH2O–
40-OH
30-OMe,40-OH
40-Cl
40-OH
30-OH
40-Cl
30-Br
9b
H
30,40-OCH2O–
30-Br
3.65
4.44
4.09
4.29
+
3.57
4.06
4.09
4.33
ꢀ0.08
ꢀ0.38
0.00
0.04
10aa
10c
10o
5,7-DiOH
7-OH
6-OH-8-Allyl
++
++
+
30,40-OCH2O–
40-OH
a
The compounds were used as test set.
Activity scale: +++ (highly active); ++ (moderately active); + (weakly active).
N.D. means not determined.
b
c
Figure 1. Effects of flavonoids on relaxation in aortic rings with endothelium pre-contracted with 1 lM phenylephrine. Flavonoids were added cumulatively to achieve the
appropriate concentrations. Results are expressed as means standard error of mean in terms of percentage relaxation of the contraction to PE (n = 4). (a) Representative
flavonoids (7b, 7j, 8i, 8k and 8o) with good relaxation effect; (b) representative flavonoids (7l, 8l, 10a and 10c) with moderate relaxation effect; and (c) representative
flavonoids (7o, 8h, 9a and 10o) with weak relaxation effect.
on C-5 position of A-ring. For example, the compounds 8l, 8o and
8p which bearing hydroxyl group on B-ring displayed slightly
weaker vasorelaxant activity than compounds 8k and 8q.
from which biological activity of newly designed molecules can be
predicted. Herein, the compounds with available EC50 (7a–b, 7j–l,
8a–b, 8d, 8i–l, 8n–q, 9b, 10a, 10c and 10o) were selected for devel-
opment a 3D-QSAR model using CoMFA method, and divided into
training set (n = 16) and test set (n = 3). The pEC50 values of these
compounds were used as dependent variables. As shown in Table
2, a CoMFA model was developed with conventional correlation
coefficient r2 = 0.872 and LOO cross-validated coefficient
2.3. CoMFA analysis
3D-QSAR methods,15–17 especially CoMFA,16 are widely used in
drug design, because they allow rapid generation of QSAR models,

X. Dong et al. / Bioorg. Med. Chem. 17 (2009) 716–726
719
Table 2
Summary of CoMFA analysis
CoMFA model
Result
R2 cross-validated (q2)
Number of components
Non cross-validated r2
Standard error of estimate
F
0.496
3
0.872
0.170
27.224
51.8%
48.2%
Steric contribution
Electrostatic contribution
q2cv = 0.496, the contribution of steric and electrostatic fields are
51.8% and 48.2%, respectively. Furthermore, we applied a test set
to verify if the model can also estimate the activity of compounds
that are structurally distinct from those included in the training
set. The theoretical results of three compounds from test set were
in good agreement with the experimental values, except for com-
pound 10a whose deviation between experimental and calculated
pEC50 is 0.38. The actual and calculated activity values for training
and test set compounds are shown in Table 1 and Figure 2.
The steric contour plot was shown in Figure 3a. It was found
that a medium-sized yellow colored contour was surrounding
ortho- and meta-positions of the B-ring of flavone and aurone
derivatives. This meant that the bulky substituents at ortho-
and meta-positions on B-ring of flavone and aurone derivatives
would decrease the potency of vasorelaxant activities. For exam-
ple, compounds 9b and 10c displayed weaker potency of vasore-
laxant activity, which might due to the fact that methlenedioxyl
groups on B-ring of these two compounds are too bulky. In addi-
tion, a medium-sized green colored contour was surrounding
ortho- and meta-positions of the B-ring of flavanone derivatives.
So, the bulky substituents at ortho- and meta-positions on B-ring
would increase the potency of vasorelaxant activities. For in-
stance, flavanones 8b and 8k exhibited more potent than 8a
and 8m, respectively.
The electrostatic contour plot is shown in Figure 3b. The blue
contour defines a region where an increase in the positive charge
will result in enhanced activity, whereas the red contour defines
a region of space where increasing electron density is favorable.
As shown in Figure 3b, the flavanones bearing 6-hydroxyl group
displayed higher potency of vasorelaxant activity (8q > 8n, 8g),
which might due to the fact that hydroxyl group is associated with
electronegative substituents. The similar results were observed in
the weakly active chalcone derivatives 7k, 7l and 7o which have
a negatively charged allyl group inside red contour region. It was
found that three medium-sized blue colored contour was sur-
rounding the bond between C-2 and C-3 position of flavanone, fla-
vone and aurone derivatives. This meant that the negative
negatively charged double bond between C-2 and C-3 would result
in decreased activity. In addition, the compounds with high activ-
Figure 2. CoMFA calculated vs actual pEC50 values.
ity (8b, 8p, 8q and 8k) usually have a methylene group of allyl or
methylenedioxyl group to occupy another two big blue contour re-
gions. The contours in both cases are seen mainly close to the basic
skeleton, which is important for designing new chemistries.
3. Conclusion
By optimizing the formerly discovered lead compound and car-
rying out structure-activity relationship analysis, a series of chal-
cone and flavanone derivatives with high vasodilatory activity
(EC50, Emax) were developed. 3D-QSAR analysis using CoMFA was
performed to explore comprehensive structure-activity relation-
ships and a statistically reliable model with good predictive power
(r2 = 0.872, qc2v = 0.496) was established on the basis of the com-
mon substructure-based alignment. According to the CoMFA con-
tours, the details on the relationship linking structure and
activity as well as clues for structural modifications that can im-
prove the activity are provided. The model would be used to design
more potent flavonoids derivatives as vasorelaxant agents and pre-
dict their activity prior to synthesis.
4. Experiment
4.1. Chemistry
Melting points were obtained on a B-540 Büchi melting-point
apparatus and are uncorrected. 1H NMR spectra was recorded on
a Brüker AM 400 instrument at 400 MHz (chemical shifts are ex-
pressed as d values relative to TMS as internal standard). ESI (posi-
tive) was recorded on an Esquire-LC-00075 spectrometer.
Compounds 2a–c were obtained by selective methoxymethyla-
tion of 1a–c with chloromethoxylmethyl ether in K2CO3/acetone,
respectively, according to the approach in Ref. 18.
Figure 3. Electrostatic map and steric map from the CoMFA model. Compounds 7j, 8q, 9a and 10a were shown inside the field. (a) The favorable steric areas with more bulk
are indicated by green isopleths, where as the disfavorable steric areas are shown by yellow isopleths. (b) The favorable electrostatic areas with positive charges are indicated
by blue isopleths, whereas the favorable electrostatic areas with negative charges are show by red isoplet.

720
X. Dong et al. / Bioorg. Med. Chem. 17 (2009) 716–726
4.2. General procedure for synthesis of allylated acetophenone
(3a–c)
(515.3 mg, 68%), mp: 105–107 °C; 1H NMR (CDCl3, 400 M, d):
3.50 (s, 3H), 3.56 (s, 3H), 5.20 (s, 2H), 5.30 (s, 2H), 6.04 (s, 2H),
6.26 (d, 1H, J = 2.4 Hz), 6.33 (d, 1H, J = 2.4 Hz), 6.86 (d, 1H,
J = 8.0 Hz), 7.11 (dd, 1H, J = 2.0, 8.0 Hz), 7.12 (d, 1H, J = 2.0 Hz),
7.74 (d, 1H, J = 15.6 Hz), 7.79 (d, 1H, J = 15.6 Hz), 13.90 (s, 1H,
OH). ESI-MS: m/z [M+H]+ 389.
A solution of compound 2, allyl bromide and K2CO3 in 100 mL
DMF was heated at 100 °C under N2 atmosphere for 6 h, then
poured into cold water and extracted with ethyl acetate. The or-
ganic phase was washed with brine and then dried over anhydrous
Na2SO4. After removal of the solvent, the residue was dissolved in
N,N-dimethylaniline and then heated at 220 °C for 2.5 h. The mix-
ture was concentrated in vacuum, and the residue was purified
over silicon gel column using petroleum ether/ethyl acetate
(30:1, v/v) as eluent gave 3.
4.3.3. 2-Hydroxy-4-methoxymethoxy-30,40-methylenedioxy-
chalcone (4c)
Reagent: compound 2b (500.3 mg, 2.55 mmol), 3,4-methylene-
dioxy-benzaldehyde (402.0 mg, 2.68 mmol). Yellow solid
(544.2 mg, 65%), mp: 130–133 °C; 1H NMR (CDCl3, 400 M, d): 3.51
(s, 3H), 5.24 (s, 2H), 6.06 (s, 2H), 6.60 (dd, 1H, J = 2.0, 8.0 Hz), 6.65
(d, 1H, J = 2.0 Hz), 6.87 (d, 1H, J = 8.4 Hz), 7.16 (d, 1H, J = 8.4 Hz),
7.19 (s, 1H), 7.42 (d, 1H, J = 15.2 Hz), 7.82 (d, 1H, J = 15.2 Hz), 7.85
(d, 1H, J = 8.0 Hz), 13.35 (s, 1H, OH). ESI-MS: m/z [M+H]+ 329.
4.2.1. 2-Hydroxy-3-allyl-4,6-dimethoxymethoxy-acetophenone
(3a)
Reagent: compound 2a (10.0 g, 39.1 mmol), allyl bromide
(14.2 g, 117 mmol). Yellow oil (5.8 g, 51%); 1H NMR (CDCl3,
400 MHz, d): 2.60 (s, 3H), 3.41 (d, 1H, J = 6.0 Hz), 3.45 (s, 3H),
3.51 (s, 3H), 4.95 (dd, 1H, J = 1.6, 9.6 Hz), 5.02 (dd, 1H, J = 1.6,
16.8 Hz), 5.95 (m, 1H), 5.22 (s, 2H), 5.25 (s, 2H), 6.40 (s, 1H),
13.85 (s, 1H, OH). ESI-MS: m/z [M+H]+ 297.
4.3.4. 2-Hydroxy-5-methoxymethoxy-30-bromo-chalcone (4d)
Reagent: compound 2c (500.1 mg, 2.55 mmol), 3-bromo-benz-
aldehyde (495.6 mg, 2.68 mmol). Yellow solid (620.5 mg, 67%),
mp: 101–103 °C; 1H NMR (CDCl3, 400 M, d): 3.49 (s, 3H), 5.22 (s,
2H), 6.90 (dd, 1H, J = 2.4, 8.0 Hz), 6.96 (d, 1H, J = 8.0 Hz), 7.30 (d,
1H, J = 2.4 Hz), 7.34 (t, 1H, J = 8.0 Hz), 7.51 (d, 1H, J = 16.0 Hz),
7.64 (d, 2H, J = 8.0 Hz), 7.73 (d, 1H, J = 2.0 Hz), 7.90 (d, 1H,
J = 16.0 Hz), 12.95 (s, 1H, OH). ESI-MS: m/z [M+H]+ 363.
4.2.2. 2-Hydroxy-3-allyl-4-methoxymethoxy-acetophenone
(3b)
Reagent: compound 2b (10.0 g, 51.0 mmol), allyl bromide
(18.5 g, 153 mmol). Yellow oil (4.6 g, 38%); 2.57 (s, 3H), 3.42 (d,
1H, J = 6.0 Hz), 3.49 (s, 3H), 4.96 (dd, 1H, J = 1.6, 9.6 Hz), 5.04 (dd,
1H, J = 1.6, 16.8 Hz), 5.21 (s, 2H), 5.98 (m, 1H), 6.68 (d, 1H,
J = 8.4 Hz), 7.61 (d, 1H, J = 8.4 Hz), 13.87 (s, 1H, OH). ESI-MS: m/z
[M+H]+ 237.
4.3.5. 2-Hydroxy-4,6-dimethoxymethoxy-3-allyl-30-bromo-
chalcone (4e)
Reagent: compound 3a (499.8 mg, 1.69 mmol), 3-bromo-benz-
aldehyde (328.0 mg, 1.77 mmol). Yellow syrup (492.5 mg, 63%);
1H NMR (CDCl3, 400 M, d): 3.43 (d, 2H, J = 6.0 Hz), 3.51 (s, 3H),
3.54 (s, 3H), 4.95 (dd, 1H, J = 1.2, 9.6 Hz), 5.06 (dd, 1H, J = 1.2,
16.8 Hz), 5.22 (s, 2H), 5.26 (s, 2H), 5.98 (m, 1H), 6.40 (s, 1H), 7.27
(t, 1H, J = 8.0 Hz), 7.50 (t, 2H, J = 8.0 Hz), 7.70 (d, 1H, J = 16.0 Hz),
7.72 (s, 1H), 7.90 (d, 1H, J = 16.0 Hz), 13.74 (s, 1H, OH). ESI-MS:
m/z [M+H]+ 463.
4.2.3. 2-Hydroxy-3-allyl-5-methoxymethoxy-acetophenone
(3c)
Reagent:compound 2c (10.0 g, 51.0 mmol), allylbromide (18.5 g,
153 mmol). Yellow oil (6.7 g, 56%); 2.59 (s, 3H), 3.41 (d, 1H,
J = 6.0 Hz), 3.48 (s, 3H), 5.01 (dd, 1H, J = 1.6, 9.6 Hz), 5.12 (dd, 1H,
J = 1.6, 16.8 Hz), 5.22 (s, 2H), 5.96 (m, 1H), 7.06 (d, 1H, J = 2.0 Hz),
7.33 (d, 1H, J = 2.0 Hz), 13.85 (s, 1H, OH). ESI-MS: m/z [M+H]+ 237.
4.3.6. 2-Hydroxy-4,6-dimethoxymethoxy-3-allyl-30-chloro-
chalcone (4f)
Reagent: compound 3a (500.4 mg, 1.69 mmol), 3-chloro-benz-
aldehyde (249.4 mg, 1.78 mmol). Yellow syrup (424.5 mg, 60%);
1H NMR (CDCl3, 400 M, d): 3.42 (d, 2H, J = 6.0 Hz), 3.51 (s, 3H),
3.53 (s, 3H), 4.98 (dd, 1H, J = 1.2, 9.6 Hz), 5.01 (dd, 1H, J = 1.2,
16.8 Hz), 5.21 (s, 2H), 5.25 (s, 2H), 5.99 (m, 1H), 6.41 (s, 1H), 7.21
(t, 1H, J = 8.0 Hz), 7.50 (t, 2H, J = 8.0 Hz), 7.65 (d, 1H, J = 16.0 Hz),
7.73 (s, 1H), 7.87 (d, 1H, J = 16.0 Hz), 13.75 (s, 1H, OH). ESI-MS:
m/z [M+H]+ 419.
4.3. General procedure for synthesis of chalcones (4a–q)
To a cold solution of the 2-hydroxy-acetophenone 2 or 3 and
appropriate benzaldehyde in 3 mL H2O–EtOH (1/4, v/v), 3 mL 20%
KOH solution (H2O–EtOH 1/4, v/v) was added. The resulting mixture
was stirred at room temperature for 24 h. The mixture was poured
into ice–water, acidified to pH ꢁ 5 with 1 N HCl, and extracted with
ethyl acetate. The organic phase was washed with brine, dried over
anhydrous Na2SO4, and concentrated in vacuo. The residue was puri-
fied on silica gel column using petroleum ether/ethyl acetate
(20:1 ꢁ 10:1, v/v) as eluent gave chalcone 4.
4.3.7. 2-Hydroxy-4,6-dimethoxymethoxy-3-allyl-40-chloro-
chalcone (4g)
Reagent: compound 3a (500.2 mg, 1.69 mmol), 4-chloro-benz-
aldehyde (249.3 mg, 1.77 mmol). Yellow solid (410.2 mg, 58%),
mp: 89–91 °C; 1H NMR (CDCl3, 400 M, d): 3.41 (d, 2H, J = 6.0 Hz),
3.50 (s, 3H), 3.53 (s, 3H), 4.97 (dd, 1H, J = 1.6, 10.0 Hz), 5.04 (dd,
1H, J = 1.6, 16.8 Hz), 5.26 (s, 2H), 5.30 (s, 2H), 5.97 (m, 1H), 6.42
(s, 1H), 7.39 (d, 2H, J = 8.0 Hz), 7.54 (d, 2H, J = 8.0 Hz), 7.72 (d,
1H, J = 16.0 Hz), 7.88 (d, 1H, J = 16.0 Hz), 13.79 (s, 1H, OH). ESI-
MS: m/z [M+H]+ 419.
4.3.1. 2-Hydroxy-4,6-dimethoxymethoxy-30-bromo-chalcone
(4a)
Reagent: compound 2a (500.1 mg, 1.95 mmol), 3-bromo-benz-
aldehyde (379.4 mg, 2.05 mmol). Yellow solid (586 mg, 71%), mp:
73–75 °C. 1H NMR (CDCl3, 400 MHz, d): 3.50 (s, 3H), 3.57 (s, 3H),
5.21 (s, 2H), 5.31 (s, 2H), 6.25 (d, 1H, J = 2.4 Hz), 6.34 (d, 1H,
J = 2.4 Hz), 7.29 (t, 1H, J = 8.0 Hz), 7.52 (t, 2H, J = 8.0 Hz), 7.69 (d,
1H, J = 16.0 Hz), 7.76 (s, 1H), 7.92 (d, 1H, J = 16.0 Hz), 13.75 (s,
1H, OH). ESI-MS: m/z [M+H]+ 423.
4.3.8. 2-Hydroxy-4,6-dimethoxymethoxy-3-allyl-40-methoxy-
chalcone (4h)
Reagent: compound 3a (499.9 mg, 1.69 mmol), 4-methoxy-
benzaldehyde (241.2 mg, 1.77 mmol). Yellow solid (384.6 mg,
55%), mp: 80–82 °C; 1H NMR (CDCl3, 400 M, d): 3.42 (d, 2H,
J = 6.0 Hz), 3.49 (s, 3H), 3.53 (s, 3H), 3.76 (s, 3H), 4.99 (dd, 1H,
J = 1.6, 10.0 Hz), 5.07 (dd, 1H, J = 1.6, 17.2 Hz), 5.22 (s, 2H), 5.28
4.3.2. 2-Hydroxy-4,6-dimethoxymethoxy-30,40-
methylenedioxy-chalcone (4b)
Reagent: compound 2a (500.0 mg, 1.95 mmol), 3,4-methylene-
dioxy-benzaldehyde (307.6 mg, 2.05 mmol). Yellow solid

X. Dong et al. / Bioorg. Med. Chem. 17 (2009) 716–726
721
(s, 2H), 5.98 (m, 1H), 6.40 (s, 1H), 7.02 (d, 2H, J = 8.4 Hz), 7.59 (d,
2H, J = 8.4 Hz), 7.71 (d, 1H, J = 16.0 Hz), 7.82 (d, 1H, J = 16.0 Hz),
13.86 (s, 1H, OH). ESI-MS: m/z [M+H]+ 415.
mp: 115–117 °C; 1H NMR (CDCl3, 400 M, d): 3.42 (d, 2H,
J = 6.0 Hz), 3.51 (s, 3H), 5.10 (dd, 1H, J = 1.6, 9.6 Hz), 5.14 (dd, 1H,
J = 1.6, 16.8 Hz), 5.20 (s, 2H), 6.00 (m, 1H), 6.76 (d, 1H, J = 8.0 Hz),
7.38 (d, 2H, J = 8.4 Hz), 7.48 (d, 1H, J = 16.0 Hz), 7.53 (d, 2H,
J = 8.4 Hz), 7.80 (d, 1H, J = 8.0 Hz), 7.81 (d, 1H, J = 16.0 Hz), 13.49
(s, 1H, OH). ESI-MS: m/z [M+H]+ 359.
4.3.9. 2-Hydroxy-30,4,6-trimethoxymethoxy-3-allyl-chalcone
(4i)
Reagent: compound 3a (500.0 mg, 1.69 mmol), 3-methoxyme-
thoxy-benzaldehyde (294.4 mg, 1.77 mmol). Yellow syrup
(457.5 mg, 61%). 1H NMR (CDCl3, 400 MHz, d): 3.43 (d, 2H,
J = 6.0 Hz), 3.48 (s, 3H), 3.49 (s, 3H), 3.52 (s, 3H), 4.96 (dd, 1H,
J = 1.6, 10.0 Hz), 5.05 (dd, 1H, J = 1.6, 17.2 Hz), 5.19 (s, 2H), 5.22
(s, 2H), 5.28 (s, 2H), 6.41 (s, 1H), 7.08 (dd, 1H, J = 2.0, 8.0 Hz),
7.21 (d, 1H, J = 8.0 Hz), 7.30 (t, 1H, J = 8.0 Hz), 7.31 (s, 1H), 7.71
(d, 1H, J = 16.0 Hz), 7.88 (d, 1H, J = 16.0 Hz), 13.75 (s, 1H). ESI-
MS: m/z [M+H]+ 445.
4.3.15. 2-Hydroxy-40,5-dimethoxymethoxy-3-allyl-chalcone
(4o)
Reagent: compound 3c (500.2 mg, 2.12 mmol), 4-methoxyme-
thoxy-benzaldehyde (369.4 mg, 2.22 mmol). Yellow solid
(431.4 mg, 53%), mp: 90–92 °C; 1H NMR (CDCl3, 400 M, d): 3.46
(d, 2H, J = 6.0 Hz), 3.51 (s, 3H), 3.54 (s, 3H), 5.11 (dd, 1H, J = 1.6,
9.6 Hz), 5.14 (dd, 1H, J = 1.6, 16.8 Hz), 5.17 (s, 2H), 5.25 (s, 2H),
6.03 (m, 1H), 7.11 (d, 2H, J = 8.0 Hz), 7.16 (d, 1H, J = 2.4 Hz), 7.47
(d, 1H, J = 2.4 Hz), 7.51 (d, 1H, J = 16.0 Hz), 7.64 (d, 2H, J = 8.0 Hz),
7.90 (d, 1H, J = 16.0 Hz), 12.96 (s, 1H, OH). ESI-MS: m/z [M+H]+ 385.
4.3.10. 2-Hydroxy-4,40,6-trimethoxymethoxy-3-allyl-chalcone
(4j)
Reagent: compound 3a (500.2 mg, 1.69 mmol), 4-methoxyme-
thoxy-benzaldehyde (294.5 mg, 1.77 mmol). Yellow syrup
(442.7 mg, 59%). 1H NMR (CDCl3, 400 M, d): 3.40 (d, 2H,
J = 5.6 Hz), 3.48 (s, 3H), 3.49 (s, 3H), 3.52 (s, 3H), 4.96 (dd, 1H,
J = 1.2, 10.0 Hz), 5.02 (dd, 1H, J = 1.2, 17.2 Hz), 5.22 (s, 2H), 5.24
(s, 2H), 5.28 (s, 2H), 5.96 (m, 1H), 6.41 (s, 1H), 7.06 (d, 2H,
J = 8.4 Hz), 7.55 (d, 2H, J = 8.4 Hz), 7.77 (d, 1H, J = 16.0 Hz), 7.83
(d, 1H, J = 16.0 Hz), 13.89 (s, 1H, OH). ESI-MS: m/z [M+H]+ 445.
4.3.16. 2-Hydroxy-30,5-dimethoxymethoxy-3-allyl-chalcone
(4p)
Reagent: compound 3c (500.0 mg, 2.12 mmol), 3-methoxyme-
thoxy-benzaldehyde (369.3 mg, 2.22 mmol). Yellow solid
(463.7 mg, 57%), mp: 86–87 °C; 1H NMR (CDCl3, 400 M, d): 3.46
(d, 2H, J = 6.0 Hz), 3.50 (s, 3H), 3.52 (s, 3H), 5.13 (dd, 1H, J = 1.2,
9.6 Hz), 5.13 (dd, 1H, J = 1.2, 16.8 Hz), 5.18 (s, 2H), 5.25 (s, 2H),
6.03 (m, 1H), 7.14 (dd, 1H, J =2.0, 8.0 Hz), 7.17 (d, 1H, J = 2.0 Hz),
7.33 (d, 1H, J = 8.0 Hz), 7.34 (s, 1H), 7.37 (t, 1H, J = 8.0 Hz), 7.46
(d, 1H, J = 2.0 Hz), 7.57 (d, 1H, J = 15.6Hz), 7.88 (d, 1H,
J = 15.6 Hz), 12.84 (s, 1H, OH). ESI-MS: m/z [M+H]+ 385.
4.3.11. 2-Hydroxy-4-methoxymethoxy-3-allyl-30,40-
methylenedioxy-chalcone (4k)
Reagent: compound 3b (500.1 mg, 2.12 mmol), 3,4-methylene-
dioxy-benzaldehyde (333.8 mg, 2.23 mmol). Yellow solid
(506.9 mg, 65%), mp: 110–112 °C. 1H NMR (CDCl3, 400 M, d): 3.45
(d, 2H, J = 6.0 Hz), 3.51 (s, 3H), 5.10 (dd, 1H, J = 1.6, 9.6 Hz), 5.13
(dd, 1H, J = 1.6, 16.8 Hz), 5.20 (s, 2H), 6.00 (m, 1H), 6.06 (s, 2H),
6.71 (d, 1H, J = 8.4 Hz), 6.85 (d, 1H, J = 8.4 Hz), 7.14 (dd, 1H,
J = 2.0, 8.4 Hz), 7.18 (d, 1H, J = 2.0 Hz), 7.48 (d, 1H, J = 15.2 Hz),
7.78 (d, 1H, J = 8.4 Hz), 7.85 (d, 1H, J = 15.2 Hz), 13.49 (s, 1H, OH).
ESI-MS: m/z [M+H]+ 369.
4.3.17. 2-Hydroxy-5-methoxymethoxy-3-allyl-40-chloro-
chalcone (4q)
Reagent: compound 3c (500.1 mg, 2.12 mmol), 4-chloro-benz-
aldehyde (312.6 mg, 2.23 mmol). Yellow solid (455.8 mg, 60%),
mp: 100–102 °C; 1H NMR (CDCl3, 400 M, d): 3.47 (d, 2H,
J = 6.0 Hz), 3.52 (s, 3H), 5.12 (dd, 1H, J = 1.6, 9.6 Hz), 5.15 (dd, 1H,
J = 1.6, 16.8 Hz), 5.24 (s, 2H), 6.02 (m, 1H), 7.16 (d, 1H, J = 2.4 Hz),
7.38 (d, 2H, J = 8.4 Hz), 7.45 (d, 1H, J = 2.4 Hz), 7.52 (d, 1H,
J = 16.0 Hz), 7.56 (d, 2H, J = 8.4 Hz), 7.88 (d, 1H, J = 16.0 Hz), 12.60
(s, 1H, OH). ESI-MS: m/z [M+H]+ 359.
4.3.12. 2-Hydroxy-4,40-dimethoxymethoxy-3-allyl-chalcone (4l)
Reagent: compound 3b (500.1 mg, 2.12 mmol), 4-methoxyme-
thoxy-benzaldehyde (369.4 mg, 2.23 mmol). Yellow solid
(471.9 mg, 58%), mp: 74–75 °C. 1H NMR (CDCl3, 400 M, d): 3.48
(d, 2H, J = 6.4 Hz), 3.49 (s, 3H), 3.50 (s, 3H), 4.98 (dd, 1H, J = 1.6,
9.6 Hz), 5.04 (dd, 1H, J = 1.6, 16.4 Hz), 5.23 (s, 2H), 5.28 (s, 2H),
5.99 (m, 1H), 6.70 (d, 1H, J = 8.4 Hz), 7.08 (d, 2H, J = 8.8 Hz),
7.49 (d, 1H, J = 15.2 Hz), 7.60 (d, 2H, J = 8.8 Hz), 7.79 (d, 1H,
J = 8.4 Hz), 7.86 (d, 1H, J = 15.2 Hz), 13.52 (s, 1H, OH). ESI-MS:
m/z [M+H]+ 385.
4.4. General procedure for synthesis of compounds 5a–q
A solution of 4 and 500 mg sodium acetate in 5 mL ethanol con-
taining 3 drops of water was refluxed for 24 h. The mixture was
poured into cold water and extracted with ethyl acetate. The or-
ganic phase was washed with saturated NaCl solution, dried
(Na2SO4). After removing the solvent, the residue was purified on
silica gel column using petroleum ether/ethyl acetate
(15:1 ꢁ 10:1, v/v) as eluent afforded flavanone 5.
4.3.13. 2-Hydroxy-4,40-dimethoxymethoxy-3-allyl-30-methoxy-
chalcone (4m)
4.4.1. ( )5,7-Dimethoxymethoxy-30-bromo-flavanone (5a)
Reagent: compound 4a (400.1 mg, 0.95 mmol), sodium acetate
(500 mg). Pale yellow solid (260.1 mg, 65%), mp: 101–103 °C; 1H
NMR (CDCl3, 400 M, d): 2.80 (dd, 1H, J = 2.4, 16.8 Hz), 2.97 (dd,
1H, J = 12.8, 16.8 Hz), 3.50 (s, 3H), 3.55 (s, 3H), 5.20 (s, 2H), 5.30
(s, 2H), 5.40 (dd, 1H, J = 2.4, 16.8 Hz), 6.42 (d, 1H, J = 2.4 Hz), 6.46
(d, 1H, J = 2.4 Hz), 7.30 (t, 1H, J = 8.4 Hz), 7.37 (d, 1H, J = 8.0 Hz),
7.51 (d, 1H, J = 8.0 Hz), 7.66 (s, 1H). ESI-MS: m/z [M+H]+ 423.
Reagent: compound 3b (500.3 mg, 2.12 mmol), 3-methoxy-4-
methoxymethoxy-benzaldehyde (436.3 mg, 2.23 mmol). Yellow
syrup (482.7 mg, 55%); 1H NMR (CDCl3, 400 M, d): 3.45 (d, 2H,
J = 6.0 Hz), 3.52 (s, 3H), 3.55 (s, 3H), 3.90 (s, 3H), 5.11 (dd, 1H,
J = 1.6, 9.6 Hz), 5.15 (dd, 1H, J = 1.6, 16.8 Hz), 5.20 (s, 2H), 5.25 (s,
2H), 6.01 (m, 1H), 6.73 (d, 1H, J = 8.0 Hz), 6.85 (d, 1H, J = 8.0 Hz),
7.11 (dd, 1H, J = 2.0 8.0 Hz), 7.13 (d, 1H, J = 2.0 Hz), 7.48 (d, 1H,
J = 16.0 Hz), 7.78 (d, 1H, J = 8.0 Hz), 7.81 (d, 1H, J = 16.0 Hz), 13.49
(s, 1H, OH). ESI-MS: m/z [M+H]+ 415.
4.4.2. ( )5,7-Dimethoxymethoxy-30,40-methylenedioxy-
flavanone (5b)
Reagent: compound 4b (400.0 mg, 1.03 mmol), sodium acetate
(500 mg). Pale yellow solid (248.0 mg, 62%), mp: 142–144 °C; 1H
NMR (CDCl3, 400 M, d): 2.82 (dd, 1H, J = 2.0, 16.8 Hz), 2.99 (dd,
1H, J = 12.4, 16.8 Hz), 3.51 (s, 3H), 3.54 (s, 3H), 5.22 (s, 2H), 5.38
4.3.14. 2-Hydroxy-4-methoxymethoxy-3-allyl-40-chloro-
chalcone (4n)
Reagent: compound 3b (499.9 mg, 2.12 mmol), 4-chloro-benz-
aldehyde (312.5 mg, 2.22 mmol). Yellow solid (470.8 mg, 62%),

722
X. Dong et al. / Bioorg. Med. Chem. 17 (2009) 716–726
(s, 2H), 5.41 (dd, 1H, J = 2.0, 12.4 Hz), 6.01 (s, 2H), 6.41 (d, 1H,
J = 2.4 Hz), 6.48 (d, 1H, J = 2.4 Hz), 6.81 (d, 1H, J = 8.0 Hz), 6.85
(dd, 1H, J = 2.0, 8.0 Hz), 6.94 (d, 1H, J = 2.0 Hz). ESI-MS: m/z
[M+H]+ 389.
5.20 (s, 2H), 5.24 (s, 2H), 5.34 (dd, 1H, J = 2.8, 13.4 Hz), 5.93 (m,
1H), 6.60 (s, 1H), 7.05 (d, 2H, J = 8.4 Hz), 7.41 (d, 2H, J = 8.4 Hz).
ESI-MS: m/z [M+H]+ 415.
4.4.9. ( )30,5,7-Trimethoxymethoxy-8-allyl-flavanone (5i)
Reagent: compound 4i (400.0 mg, 0.90 mmol), sodium acetate
(500 mg). Pale yellow solid (212.0 mg, 53%), mp: 72–74 °C; 1H
NMR (CDCl3, 400 MHz, d): 2.80 (dd, 1H, J = 16.8, 2.8 Hz), 2.95 (dd,
1H, J = 13.4, 16.8 Hz), 3.44 (d, 2H, J = 6.0 Hz), 3.45, (s, 3H), 3.48 (s,
3H), 3.53 (s, 3H), 4.96 (dd, 1H, J = 2.0, 9.6 Hz), 5.01 (dd, 1H,
J = 2.0, 16.4 Hz), 5.20 (s, 2H), 5.24 (s, 2H), 5.26 (s, 2H), 5.35 (dd,
1H, J = 2.8, 13.4 Hz), 5.92 (m, 1H), 6.58 (s, 1H), 7.06 (d, 1H,
J = 8.0 Hz), 7.10 (d, 1H, J = 8.0 Hz), 7.19 (s, 1H), 7.38 (1H, d,
J = 8.0 Hz). ESI-MS: m/z [M+H]+ 445.
4.4.3. ( )7-Methoxymethoxy-30,40-methylenedioxy-flavanone
(5c)
Reagent: compound 4c (399.7 mg, 1.22 mmol), sodium ace-
tate (500 mg). Pale yellow syrup (271.8 mg, 68%); 1H NMR
(CDCl3, 400 M, d): 2.83 (dd, 1H, J = 2.8, 16.8 Hz), 2.96 (dd, 1H,
J = 12.8, 16.8 Hz), 3.51 (s, 3H), 5.22 (s, 2H), 5.43 (dd, 1H, J = 2.8,
12.8 Hz), 6.03 (s, 2H), 6.72 (d, 1H, J = 2.4 Hz), 6.75 (dd, 1H,
J = 2.4, 8.4 Hz), 6.75 (d, 1H, J = 8.0 Hz), 6.86 (dd, 1H, J = 2.0,
8.0 Hz), 6.98 (d, 1H, J = 2.0 Hz), 7.89 (d, 1H, J = 8.4 Hz). ESI-MS:
m/z [M+H]+ 329.
4.4.10. ( )40,5,7-Trimethoxymethoxy-8-allyl-flavanone (5j)
Reagent: compound 4j (400.3 mg, 0.90 mmol), sodium acetate
(500 mg). Pale yellow solid (208.2 mg, 52%), mp: 77–79 °C. 1H
NMR (CDCl3, 400 MHz, d): 2.82 (dd, 1H, J = 16.4, 2.8 Hz), 2.98 (dd,
1H, J = 13.4, 16.4 Hz), 3.41 (d, 2H, J = 6.0 Hz), 3.48 (s, 3H), 3.49 (s,
3H), 3.55 (s, 3H), 4.96 (dd, 1H, J = 2.0, 9.6 Hz), 5.02 (dd, 1H,
J = 2.0, 16.4 Hz), 5.21 (s, 2H), 5.24 (s, 2H), 5.26 (s, 2H), 5.94 (m,
1H), 6.60 (s, 1H), 7.06 (d, 2H, J = 8.4 Hz), 7.40 (d, 2H, J = 8.4 Hz).
ESI-MS: m/z [M+H]+ 445.
4.4.4. ( )6-Methoxymethoxy-30-bromo-flavanone (5d)
Reagent: compound 4d (400.3 mg, 1.10 mmol), sodium acetate
(500 mg). white solid (220.2 mg, 55%), mp: 95–96 °C. 1H NMR
(CDCl3, 400 M, d): 2.87 (dd, 1H, J = 2.8, 16.8 Hz), 3.01 (dd, 1H,
J = 13.2, 16.8 Hz), 3.48 (s, 3H), 5.17 (s, 2H), 5.41(dd, 1H, J = 2.8,
13.2 Hz), 7.02 (d, 1H, J = 8.4 Hz), 7.23 (dd, 1H, J = 2.4, 8.4 Hz), 7.31
(t, 1H, J = 8.4 Hz), 7.38 (d, 1H, J = 8.4 Hz), 7.52 (dd, 1H, J = 2.4,
8.4 Hz), 7.56 (d, 1H, J = 8.4 Hz), 7.67 (s, 1H). ESI-MS: m/z [M+H]+
329.
4.4.11. ( )7-Methoxymethoxy-8-allyl-30,40-methylenedioxy-
flavanone (5k)
4.4.5. ( )5,7-Dimethoxymethoxy-8-allyl-30-bromo-flavanone
(5e)
Reagent: compound 4k (400.1 mg, 1.09 mmol), sodium acetate
(500 mg). Pale yellow syrup (232.1 mg, 58%); 1H NMR (CDCl3,
400 M, d): 2.85 (dd, 1H, J = 2.8, 16.8 Hz), 3.02 (dd, 1H, J = 12.8,
16.8 Hz), 3.43 (d, 2H, J = 6.0 Hz), 3.48 (s, 3H), 4.98 (dd, 1H, J = 1.6,
9.6 Hz), 5.03 (dd, 1H, J = 1.6, 16.4 Hz), 5.23 (s, 2H), 5.42 (dd, 1H,
J = 2.8, 12.8 Hz), 5.95 (m, 1H), 6.02 (s, 2H), 6.78 (d, 1H, J = 8.0 Hz),
6.81 (d, 1H, J = 8.0 Hz), 6.84 (dd, 1H, J = 2.0, 8.0 Hz), 6.96 (d, 1H,
J = 2.0 Hz), 7.85 (d, 1H, J = 8.0 Hz). ESI-MS: m/z [M+H]+ 369.
Reagent: compound 4e (400.1 mg, 0.86 mmol), sodium acetate
(500 mg). Pale yellow syrup (240.1 mg, 60%); 1H NMR (CDCl3,
400 M, d): 2.84 (dd, 1H, J = 2.8, 16.8 Hz), 2.94 (dd, 1H, J = 12.8,
16.8 Hz), 3.43 (d, 2H, J = 6.0 Hz), 3.49 (s, 3H), 3.55 (s, 3H), 4.99
(dd, 1H, J = 1.6, 10.0 Hz), 5.02 (dd, 1H, J = 1.6, 16.8Hz), 5.25 (s,
2H), 5.29 (s, 2H), 5.38 (dd, 1H, J = 2.8, 12.8 Hz), 5.93 (m, 1H), 6.62
(s, 1H), 7.30 (t, 1H, J = 8.0 Hz), 7.38 (d, 1H, J = 8.0 Hz), 7.51 (d, 1H,
J = 8.0 Hz), 7.65 (s, 1H). ESI-MS: m/z [M+H]+ 463.
4.4.12. ( )40,7-Dimethoxymethoxy-8-allyl-flavanone (5l)
Reagent: compound 4l (399.8 mg, 1.04 mmol), sodium acetate
(500 mg). Pale yellow solid (239.9 mg, 60%), mp: 64–66 °C; 1H
NMR (CDCl3, 400 M, d): 2.86 (dd, 1H, J = 2.8, 16.8 Hz), 3.01 (dd,
1H, J = 12.8, 16.8 Hz), 3.46 (d, 2H, J = 6.0 Hz), 3.49 (s, 3H), 3.51 (s,
3H), 4.97 (dd, 1H, J = 2.0, 10.0 Hz), 5.01 (dd, 1H, J = 2.0, 16.8Hz),
5.22 (s, 2H), 5.28 (s, 2H), 5.43 (dd, 1H, J = 2.8, 12.8 Hz), 5.93 (m,
1H), 6.84 (d, 1H, J = 8.4 Hz), 7.11 (d, 2H, J = 8.4 Hz), 7.41 (d, 2H,
J = 8.4 Hz), 7.83 (d, 1H, J = 8.4 Hz). ESI-MS: m/z [M+H]+ 385.
4.4.6. ( )5,7-Dimethoxymethoxy-8-allyl-30-chloro-flavanone
(5f)
Reagent: compound 4f (400.1 mg, 0.96 mmol), sodium acetate
(500 mg). Pale yellow solid (220.1 mg, 55%), mp: 84–86 °C; 1H
NMR (CDCl3, 400 M, d): 2.88 (dd, 1H, J = 2.8, 16.8 Hz), 2.93 (dd,
1H, J = 12.8, 16.8 Hz), 3.42 (d, 2H, J = 6.0 Hz), 3.46 (s, 3H), 3.53 (s,
3H), 4.96 (dd, 1H, J = 2.0, 9.6 Hz), 5.01 (dd, 1H, J = 2.0, 16.4 Hz),
5.22 (s, 2H), 5.28 (s, 2H), 5.40 (dd, 1H, J = 2.8, 12.8 Hz), 5.94 (m,
1H), 6.62 (s, 1H), 7.25 (t, 1H, J = 8.0 Hz), 7.36 (d, 1H, J = 8.0 Hz),
7.49 (d, 1H, J = 8.0 Hz), 7.69 (s, 1H). ESI-MS: m/z [M+H]+ 419.
4.4.13. ( )40,7-Dimethoxymethoxy-8-allyl-30-methoxy-
flavanone (5m)
4.4.7. ( )5,7-Dimethoxymethoxy-8-allyl-40-chloro-flavanone
(5g)
Reagent: compound 4m (400.2 mg, 0.97 mmol), sodium acetate
(500 mg). Pale yellow solid (236.1 mg, 59%), mp: 92–93 °C; 1H
NMR (CDCl3, 400 M, d): 2.86 (dd, 1H, J = 2.8, 16.8 Hz), 3.00 (dd,
1H, J = 12.8, 16.8 Hz), 3.46 (d, 2H, J = 6.0 Hz), 3.47 (s, 3H), 3.53 (s,
3H), 3.91(s, 3H), 4.96 (dd, 1H, J = 1.6, 9.6 Hz), 5.02 (dd, 1H, J = 1.6,
16.4 Hz), 5.26 (s, 2H), 5.27 (s, 2H), 5.40 (dd, 1H, J = 2.8, 12.8 Hz),
5.93 (m, 1H), 6.83 (d, 1H, J = 8.4 Hz), 6.94 (d, 1H, J = 8.0 Hz),7.08
(dd, 1H, J = 2.0, 8.4 Hz), 7.32 (d, 1H, J = 2.0 Hz), 7.82 (d, 1H, J = 8.0
Hz). ESI-MS: m/z [M+H]+ 415.
Reagent: compound 4g (400.0 mg, 0.96 mmol), sodium acetate
(500 mg). Pale yellow solid (240.0 mg, 60%), mp: 89–91 °C; 1H
NMR (CDCl3, 400 M, d): 2.85 (dd, 1H, J = 2.8, 16.8 Hz), 2.93 (dd,
1H, J = 12.8, 16.8 Hz), 3.43 (d, 2H, J = 6.0 Hz), 3.48 (s, 3H), 3.52 (s,
3H), 4.97 (dd, 1H, J = 2.0, 9.6 Hz), 5.02 (dd, 1H, J = 2.0, 16.4 Hz),
5.21 (s, 2H), 5.26 (s, 2H), 5.42 (dd, 1H, J = 2.8, 12.8 Hz), 5.94 (m,
1H), 6.60 (s, 1H), 7.43 (d, 2H, J = 8.4 Hz), 7.52 (d, 2H, J = 8.4 Hz).
ESI-MS: m/z [M+H]+ 419.
4.4.14. ( )7-Methoxymethoxy-8-allyl-40-chloro-flavanone (5n)
Reagent: compound 4n (400.1 mg, 1.12 mmol), sodium acetate
(500 mg). Pale yellow syrup (212.1 mg, 53%); 1H NMR (CDCl3,
400 M, d): 2.83 (dd, 1H, J = 2.8, 16.8 Hz), 3.00 (dd, 1H, J = 12.8,
16.8 Hz), 3.41 (d, 2H, J = 6.0 Hz), 3.48 (s, 3H), 4.96 (dd, 1H, J = 1.6,
9.6 Hz), 5.01 (dd, 1H, J = 1.6, 16.4 Hz), 5.23 (s, 2H), 5.42 (dd, 1H,
J = 2.8, 12.8 Hz), 5.95 (m, 1H), 6.69 (d, 1H, J = 8.0 Hz), 7.15 (d, 2H,
4.4.8. ( )5,7-Dimethoxymethoxy-8-allyl-40-methoxy-flavanone
(5h)
Reagent: compound 4h (400.2 mg, 0.97 mmol), sodium acetate
(500 mg). Pale yellow syrup (252.1 mg, 63%); 1H NMR (CDCl3,
400 MHz, d): 2.81 (dd, 1H, J = 16.4, 2.8 Hz), 2.96 (dd, 1H, J = 13.4,
16.4 Hz), 3.40 (d, 2H, J = 6.0 Hz), 3.48 (s, 3H), 3.53 (s, 3H), 3.89 (s,
3H), 4.95 (dd, 1H, J = 2.0, 9.6 Hz), 5.01 (dd, 1H, J = 2.0, 16.8 Hz),

X. Dong et al. / Bioorg. Med. Chem. 17 (2009) 716–726
723
J = 8.4 Hz), 7.44 (d, 1H, J = 8.4 Hz), 7.83 (d, 1H, J = 8.0 Hz). ESI-MS:
m/z [M+H]+ 359.
with ethyl acetate. The organic phase was washed with brine and
then dried over anhydrous Na2SO4. After removal of the solvent,
the residue was purified over silicon gel column using petroleum
ether/ethyl acetate as eluent gave 7a–b, 7j–l, 7o, 8a–q or 9a–b.
4.4.15. ( )40,6-Dimethoxymethoxy-8-allyl-flavanone (5o)
Reagent: compound 4o (400.0 mg, 1.04 mmol), sodium acetate
(500 mg). Pale yellow solid (220.1 mg, 55%), mp: 96–97 °C. 1H
NMR (CDCl3, 400 M, d): 2.85 (dd, 1H, J = 2.8, 16.8 Hz), 3.02 (dd,
1H, J = 13.2, 16.8 Hz), 3.43 (d, 2H, J = 6.0 Hz), 3.48 (s, 3H), 3.51 (s,
3H), 5.06 (dd, 1H, J = 1.6, 9.6 Hz), 5.10 (dd, 1H, J = 1.6, 16.4 Hz),
5.18 (s, 2H), 5.25 (s, 2H), 5.40 (dd, 1H, J = 2.8, 13.2), 5.98 (m, 1H),
7.08 (d, 2H, J = 8.4 Hz), 7.11 (d, 1H, J = 2.0 Hz), 7.40 (d, 1H,
J = 2.0 Hz), 7.45 (d, 2H, J = 8.4 Hz). ESI-MS: m/z [M+H]+ 385.
4.6.1. 2,4,6-Trihydroxy-30-bromo-chalcone (7a)
Reagent: compound 4a (100 mg, 0.24 mmol). Yellow amor-
phous powder (63.4 mg, 80%), mp: 168–170 °C. 1H NMR (ace-
tone-d6, 400 M, d): 5.98 (s, 2H), 7.41 (t, 1H, J = 8.0 Hz), 7.59 (dd,
1H, J = 1.6, 8.0 Hz), 7.68 (d, 1H, J = 8.0 Hz), 7.70 (d, 1H,
J = 15.6 Hz), 7.87 (t, 1H, J = 1.6 Hz), 8.24 (d, 1H, J = 15.6 Hz), 9.38
(s, 1H, OH), 11.96 (s, 2H, OH). ESI-MS: m/z [M+H]+ 335.
4.4.16. ( )30,6-Dimethoxymethoxy-8-allyl-flavanone (5p)
Reagent: compound 4p (400.3 mg, 1.04 mmol), sodium acetate
(500 mg). Pale yellow solid (244.2 mg, 61%), mp: 62–64 °C; 1H
NMR (CDCl3, 400 M, d): 2.87 (dd, 1H, J = 2.8, 16.8 Hz), 3.03 (dd,
1H, J = 13.2, 16.8 Hz), 3.42 (d, 2H, J = 6.0 Hz), 3.48 (s, 3H), 3.53 (s,
3H), 5.07 (dd, 1H, J = 1.6, 9.6 Hz), 5.12 (dd, 1H, J = 1.6, 16.4 Hz),
5.20 (s, 2H), 5.22 (s, 2H), 5.43 (dd, 1H, J = 2.8, 13.2 Hz), 5.99 (m,
1H), 7.03 (dd, 1H, J = 8.0 Hz), 7.05 (d, 1H, J = 8.0 Hz), 7.09 (d, 1H,
J = 2.0 Hz), 7.19 (s, 1H), 7.37 (d, 1H, J = 8.0 Hz), 7.43 (d, H,
J = 2.0 Hz). ESI-MS: m/z [M+H]+ 385.
4.6.2. 2,4,6-Trihydroxy-30,40-methylenedioxy-chalcone (7b)
Reagent: compound 4b (100 mg, 0.26 mmol). Yellow amor-
phous powder (57.2 mg, 74%), mp: 198–200 °C. 1H NMR (ace-
tone-d6, 400 M, d): 5.97 (s, 2H), 6.08 (s, 2H), 6.91 (d, 1H,
J = 8.4 Hz), 7.20 (d, 1H, J = 1.2, 8.4 Hz), 7.21 (d, 1H, J = 1.2 Hz),
7.72 (d, 1H, J = 15.6 Hz), 8.10 (d, 1H, J = 15.6 Hz), 9.27 (s, 1H, OH),
11.99 (s, 2H, OH). ESI-MS: m/z [M+H]+ 301.
4.6.3. 2,4,40,6-Tetra-hydroxy-3-allyl-chalcone (7j)
Reagent: compound 4j (100 mg, 0.23 mmol). Yellow amorphous
powder (46.4 mg, 66%), mp: 185–187 °C. 1H NMR (acetone-d6,
400 M, d): 3.28 (td, 2H, J = 1.6, 6.0 Hz), 4.83 (qd, 1H, J = 2.0,
12.0 Hz), 4.94 (qd, 1H, J = 2.0, 16.0 Hz), 5.87 (m, 1H), 6.06 (s, 1H),
6.85 (d, 2H, J = 8.4 Hz), 7.52 (d, 2H J = 8.4 Hz), 7.71 (d, 1H,
J = 15.6 Hz), 8.08 (d, 1H, J = 15.6 Hz), 8.82 (s, 1H, OH), 9.03 (s, 1H,
OH), 9.61 (s, 1H, OH), 14.39 (s, 1H, OH). ESI-MS: m/z [M+H]+ 313.
4.4.17. ( )6-Methoxymethoxy-8-allyl-40-chloro-flavanone (5q)
Reagent: compound 4q (400.0 mg, 1.12 mmol), sodium acetate
(500 mg). Pale yellow solid (232.0 mg, 58%), mp: 100–101 °C; 1H
NMR (CDCl3, 400 M, d): 2.88 (dd, 1H, J = 2.4, 16.4 Hz), 2.98 (dd,
1H, J = 12.8, 16.4 Hz), 3.40 (d, 2H, J = 6.4 Hz), 3.48 (s, 3H), 5.07
(dd, 1H, J = 1.6, 9.6 Hz), 5.09 (dd, 1H, J = 1.6, 16.4 Hz), 5.15 (s,
2H), 5.41 (dd, 1H, J = 2.4, 12.8 Hz), 5.95 (m, 1H), 7.11 (d, 1H,
J = 2.4 Hz), 7.41 (s, 4H), 7.44 (s, 1H, J = 2.4 Hz). ESI-MS: m/z
[M+H]+ 359.
4.6.4. 2,4-Dihydroxy-3-allyl-30,40-methylenedioxy-chalcone
(7k)
Reagent: compound 4k (100 mg, 0.27 mmol). Yellow amor-
phous powder (67.8 mg, 77%), mp: 174–175 °C. 1H NMR (ace-
tone-d6, 400 M, d): 3.53 (td, 2H, J = 1.6, 6.0 Hz), 5.16 (qd, 1H,
J = 1.6, 10.0 Hz), 5.20 (qd, 1H, J = 1.6, 16.8 Hz), 6.10 (m, 1H), 6.04
(s, 2H), 6.44 (d, 1H, J = 8.4 Hz), 6.85 (d, 1H, J = 8.4 Hz), 7.13 (dd,
1H, J = 1.6, 8.0 Hz), 7.42 (d, 1H, J = 16.0 Hz), 7.75 (d, 1H,
J = 8.4 Hz), 7.80 (d, 1H, J = 16.0 Hz), 9.26 (s, 1H, OH), 13.82 (s, 1H,
OH). ESI-MS: m/z [M+H]+ 325.
4.5. General procedure for synthesis of compounds 6a–b
A solution of 5 and mercuric acetate in 1 mL anhydrous pyridine
was heated at 60 °C for 2 h. The mixture was poured into cold
water. The precipitate was separated and purified on silica gel col-
umn using petroleum ether/ethyl acetate (12:1, v/v) as eluent
afforded 6.
4.5.1. 5,7-Methoxymethoxy-30-bromo-aurone (6a)
Reagent: compound 4a (100.0 mg, 0.24 mmol), mercuric acetate
(150.6 mg, 0.48 mmol). Yellow solid (69.7 mg, 70%), mp: 136–
138 °C; 1H NMR (CDCl3, 400 M, d): 3.52 (s, 3H), 3.54 (s, 3H), 5.27
(s, 2H), 5.37 (s, 2H), 6.53 (1H, J = 1.6 Hz), 6.66 (1H, J = 1.6 Hz),
6.67 (s, 1H), 7.30 (t, 1H, J = 8.0 Hz), 7.49 (dt, 1H, J = 8.0, 1.6 Hz),
7.74 (d, 1H, J = 8.0 Hz), 8.06 (t, 1H, J = 1.6 Hz). ESI-MS: m/z
[M+H]+ 421.
4.6.5. 2,4,40-Trihydroxy-3-allyl-chalcone (7l)
Reagent: compound 4l (100 mg, 0.52 mmol); Yellow amor-
phous powder (53.9 mg, 70%), mp: 179–182 °C. 1H NMR (ace-
tone-d6, 400 M, d): 1H NMR (acetone-d6, 400 M, d): 3.39 (td, 2H,
J = 1.6, 6.0 Hz), 4.86 (qd, 1H, J = 1.6, 10.0 Hz), 4.97 (qd, 1H, J = 1.6,
16.8 Hz), 5.95 (m, 1H), 6.51 (d, 1H, J = 8.4 Hz), 6.90 (d, 2H,
J = 8.4 Hz), 7.71 (d, 2H, J = 8.4 Hz), 7.72 (d, 1H, J = 16.0 Hz), 7.81
(d, 1H, J = 16.0 Hz), 7.97 (d, 1H, J = 8.4 Hz), 8.98 (s, 1H, OH), 9.31
(s, 1H, OH), 13.95 (s, 1H, OH).
4.5.2. 5,7-Methoxymethoxy-30,40-methylenedioxy-aurone (6b)
Reagent: compound 4b (100.0 mg, 0.26 mmol), mercuric ace-
tate (164.2 mg, 0.52 mmol). Yellow solid (74.6 mg, 75%), mp:
164–165 °C; 1H NMR (CDCl3, 400 M, d): 3.53 (s, 3H), 3.54 (s,
3H), 5.26 (s, 2H), 5.37 (s, 2H), 6.04 (s, 2H), 6.53 (1H, J = 2.0 Hz),
6.64 (1H, J = 2.0 Hz), 6.71 (s, 1H), 6.87 (d, 1H, J = 8.0 Hz), 7.28
(dd, 1H, J = 2.0, 8.0 Hz), 7.54 (d, 1H, J = 2.0 Hz). ESI-MS: m/z
[M+H]+ 387.
4.6.6. 2,40,5-Trihydroxy-3-allyl-chalcone (7o)
Reagent: compound 4o (100 mg, 0.26 mmol). Yellow amor-
phous powder (56.3 mg, 73%), mp: 152–154 °C. 1H NMR (ace-
tone-d6, 400 M, d): 3.38 (td, 2H, J = 1.6, 6.0 Hz), 5.04 (qd, 1H,
J = 1.6, 10.0 Hz), 5.11 (qd, 1H, J = 1.6, 17.2 Hz), 5.99 (m, 1H), 6.95
(d, 2H, J = 8.4 Hz), 7.02 (d, 1H, J = 2.4 Hz), 7.48 (d, 1H, J = 2.4 Hz),
7.76 (d, 1H, J = 15.2 Hz), 7.79 (d, 2H, J = 8.4 Hz), 7.88 (d, 1H,
J = 15.2 Hz), 8.00 (s, 1H, OH), 9.06 (s, 1H, OH), 12.93 (s, 1H, OH).
ESI-MS: m/z [M+H]+ 325.
4.6. General procedure for synthesis of compounds 7a–b, 7j–l,
7o, 8a–q and 9a–b
4.6.7. ( )5,7-Dihydroxy-30-bromide-flavanone (8a)
To a solution of 4a–b, 4j–l, 4o, 5a–q or 6a–b in 10 mL metha-
nol/THF(1/1, v/v), 2 mL 3 N HCl was added. The resulting mixture
was refluxed for 45 min, then poured into cold water and extracted
Reagent: compound 5a (200 mg, 0.47 mmol). White amorphous
powder (134.6 mg, 85%), mp: 217–218 °C. 1H NMR (acetone-d6,

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X. Dong et al. / Bioorg. Med. Chem. 17 (2009) 716–726
400 M, d): 2.85 (dd, 1H, J = 3.2, 17.2 Hz), 3.18 (dd, 1H, J = 12.8,
17.2 Hz), 5.61 (dd, 1H, J = 3.2, 17.2 Hz), 5.98 (d, 1H, J = 2.4 Hz),
6.02 (d, 1H, J = 2.4 Hz), 7.42 (t, 1H, J = 8.0 Hz), 7.57–7.59 (m, 2H),
7.78 (t, 1H, J = 2.4 Hz), 9.68 (s, 1H, OH), 12.13 (s, 1H, OH). ESI-
MS: m/z [M+H]+ 335.
400 M, d): 2.80 (dd, 1H, J = 17.2, 2.8 Hz), 3.13 (d, 1H, J = 12.4,
16.8 Hz), 3.28 (t, 2H, J = 6.0 Hz), 3.83 (s, 3H, OMe), 4.87 (dd, 1H,
J = 2.0, 10.4 Hz), 4.95 (dd, 1H, J = 2.0, 16.8 Hz), 5.50 (dd, J = 2.8,
12.4 Hz), 5.88 (m, 1H), 6.04 (s, 1H), 7.00 (d, 2H, J = 8.0 Hz), 7.50
(d, 2H, J = 8.0 Hz), 9.60 (s, 1H, OH), 12.15 (s, 1H, OH). ESI-MS: m/z
[M+H]+ 297.
4.6.8. ( )5,7-Dihydroxy-30,40-methylenedioxy-flavanone (8b)
Reagent: compound 5b (100 mg, 0.26 mmol). White amorphous
powder (63.4 mg, 82%), mp: 215–216 °C. 1H NMR (acetone-d6,
400 M, d): 2.75 (dd, 1H, J = 2.4, 16.4 Hz), 3.18 (dd, 1H, J = 12.4,
16.4 Hz), 5.48 (dd, 1H, J = 2.4, 16.4 Hz), 5.95 (d, 1H, J = 2.0 Hz),
5.97 (d, 1H, J = 2.0 Hz), 6.04 (s, 2H), 6.89 (d, 1H, J = 7.6 Hz), 7.03
(dd, 1H, J = 1.6, 7.6 Hz), 7.10 (d, 1H, J = 1.6 Hz), 9.67 (s, 1H, OH),
12.15 (s, 1H, OH). ESI-MS: m/z [M+H]+ 301.
4.6.15. ( )30,5,7-Trihydroxy-8-allyl-flavanone (8i)
Reagent: compound 5i (100 mg, 0.23 mmol). White amorphous
powder (45.7 mg, 65%), mp: 188–190 °C. 1H NMR (acetone-d6,
400 M, d): 2.79 (dd, 1H, J = 2.8, 16.8 Hz), 3.02 (dd, 1H, J = 12.4,
16.8 Hz), 3.26 (d, 2H, J = 6.0 Hz), 4.84 (dd, 1H, J = 2.0, 9.6 Hz), 4.93
(dd, 1H, J = 2.0, 16.8 Hz), 5.46 (dd, J = 2.8, 12.4 Hz), 5.85 (m, 1H),
6.00 (s, 1H), 6.80 (dd, J = 2.0, 8.0 Hz), 6.97 (d, 1H, J = 8.0 Hz), 7.01
(d, 1H, J = 2.0 Hz), 7.21 (t, 1H, J = 8.0 Hz), 8.45 (s, 1H, OH), 9.54
(s,1H, OH), 12.09 (s, 1H, OH). ESI-MS: m/z [M+H]+ 313.
4.6.9. ( )7-Hydroxy-30,40-methylenedioxy-flavanone (8c)
Reagent: compound 5c (100 mg, 0.30 mmol). White amorphous
powder (67.5 mg, 78%), mp: 181–183 °C. 1H NMR (acetone-d6,
400 M, d): 2.78 (dd, 1H, J = 2.8, 16.8 Hz), 3.03 (dd, 1H, J = 12.8,
16.8 Hz), 5.60 (dd, J = 2.8, 12.8 Hz), 6.48 (d, 1H, J = 2.0 Hz), 6.60
(dd, J = 2.0, 8.4 Hz), 7.01 (d, 1H, J = 8.0 Hz), 7.05 (dd, 1H, J = 1.2,
8.0 Hz), 7.08 (d, J = 1.2 Hz), 9.46 (s, 1H, OH). ESI-MS: m/z [M+H]+
285.
4.6.16. ( )40,5,7-Trihydroxy-8-allyl-flavanone (8j)
Reagent: compound 5j (100 mg, 0.23 mmol). White amorphous
powder (47.8 mg, 68%), mp: 195–196 °C. 1H NMR (acetone-d6,
400 M, d): 2.75 (dd, 1H, J = 16.4, 2.8 Hz), 3.03 (d, 1H, J = 12.0,
16.4 Hz), 3.26 (d, 2H, J = 6.0 Hz), 4.88 (dd, 1H, J = 2.0, 9.6 Hz), 4.88
(dd, 1H, J = 2.0, 9.6 Hz), 4.95 (dd,1H, J = 2.0, 12.0 Hz), 5.44 (dd,
J = 2.8, 12.4 Hz), 6.01 (s, 1H), 7.05 (d, 2H, J = 8.0 Hz), 7.35 (d, 2H,
J = 8.0 Hz), 8.65 (s, 1H, OH), 9.58 (s, 1H, OH), 12.11 (s, 1H, OH).
ESI-MS: m/z [M+H]+ 313.
4.6.10. ( )6-Hydroxy-30-bromide-flavanone (8d)
Reagent: compound 5 d (100 mg, 0.28 mmol). White amor-
phous powder (70.3 mg, 80%), mp: 174–175 °C. 1H NMR (ace-
tone-d6, 400 M, d): 2.85 (dd, 1H, J = 2.8, 16.8 Hz), 3.08 (dd, 1H,
J = 12.8, 16.8 Hz), 5.57 (dd, J = 2.8, 12.8 Hz), 6.99 (d, 1H,
J = 8.4 Hz), 7.11 (dd, J = 2.4, 8.4 Hz), 7.25 (d, 1H, J = 2.4 Hz), 7.41
(t, 1H, J = 8.4 Hz), 7.58 (t, 2H, J = 8.4 Hz), 7.80 (s, 1H), 8.38 (s, 1H,
OH). ESI-MS: m/z [M+H]+ 319.
4.6.17. ( )7-Hydroxy-8-allyl-30,40-methylenedioxy-flavanone
(8k)
Reagent: compound 5k (100 mg, 0.27 mmol). White amorphous
powder (66.1 mg, 75%), mp: 171–173 °C. 1H NMR (acetone-d6, 400
M, d): 2.80 (dd, 1H, J = 3.6, 16.8 Hz), 2.98 (dd, 1H, J = 12.8, 16.8 Hz),
3.47 (d, 2H, J = 6.4 Hz), 5.10–5.16 (m, 2H), 5.37 (dd, 1H, J = 3.6,
12.8 Hz), 5.96 (m, 1H), 6.00 (d, 2H, J = 0.8 Hz), 6.57 (d, 1H,
J = 8.0 Hz), 6.84 (d, 1H, J = 8.0 Hz), 6.90 (dd, 1H, J = 1.2, 8.0 Hz),
6.98 (d, 1H, J = 1.2 Hz), 7.77 (d, 1H, J = 8.0 Hz), 9.22 (s, 1H, OH).
ESI-MS: m/z [M+H]+ 325.
4.6.11. ( )5,7-Dihydroxy-8-allyl-30-bromide-flavanone (8e)
Reagent: compound 5e (100 mg, 0.22 mmol); White amor-
phous powder (59.1 mg, 73%), mp: 151–153 °C. 1H NMR (ace-
tone-d6, 400 M, d): 2.82 (dd, 1H, J = 16.8, 2.8 Hz), 3.09 (d, 1H,
J = 12.4, 16.8 Hz), 3.32 (t, 2H, J = 6.0 Hz), 4.84 (dd, 1H, J = 2.0,
9.6 Hz), 4.95 (dd, 1H, J = 2.0, 16.8 Hz), 5.56 (dd, 1H, J = 2.8,
12.4 Hz), 6.05 (s, 1H), 7.37 (t, 1H, J = 8.0 Hz), 7.53 (d, 2H,
J = 8.0 Hz), 7.75 (s, 1H), 9.59 (s, 1H, OH), 12.08 (s, 1H, OH).
ESI-MS: m/z [M+H]+ 375.
4.6.18. ( )40,7-Dihydroxy-8-allyl-flavanone (8l)
Reagent: compound 5l (100 mg, 0.26 mmol); White amorphous
powder (56.3 mg, 73%), mp: 178–181 °C. 1H NMR (acetone-d6,
400 M, d): 2.68 (dd, 1H, J = 2.8, 16.0 Hz), 2.94 (dd, 1H, J = 12.4,
16.0 Hz), 3.34 (d, 2H, J = 6.8 Hz), 4.88 (m, 1H), 4.93 (m, 1H), 5.40
(dd, 1H, J = 2.8, 12.4 Hz), 5.87 (m, 1H), 6.59 (d, 1H, J = 8.4 Hz),
6.85 (d, 2H, J = 8.4 Hz), 7.37 (d, 2H, J = 8.4 Hz), 7.57 (d, 1H,
J = 8.4), 8.41 (s, 1H, OH), 9.18 (s, 1H, OH). ESI-MS: m/z [M+H]+ 297.
4.6.12. ( )5,7-Dihydroxy-30-chloro-8-allyl-flavanone (8f)
Reagent: compound 5f (100 mg, 0.24 mmol). White amorphous
powder (59.2 mg, 75%), mp: 135–136 °C. 1H NMR (acetone-d6,
400 M, d): 2.93 (dd, 1H, J = 16.8, 3.6 Hz), 3.17 (d, 1H, J = 12.4,
16.8 Hz), 3.33 (d, 2H, J = 6.0 Hz), 4.91 (dd, 1H, J = 1.6, 10.0 Hz),
4.97 (dd, 1H, J = 1.6, 16.8 Hz), 5.65 (dd, J = 3.6, 12.4 Hz), 5.89 (m,
1H), 6.10 (s, 1H), 7.43 (d, 1H, J = 8.0 Hz), 7.49 (t, 1H, J = 8.0 Hz),
7.55 (d, 1H, J = 8.0 Hz), 7.65 (s, 1H), 9.65 (s, 1H, OH), 12.01 (s, 1H,
OH). ESI-MS: m/z [M+H]+ 331.
4.6.19. ( ) 40,7-Dihydroxy-8-allyl-30-methoxy-flavanone (8m)
Reagent: compound 5m (100 mg, 0.24 mmol). White amor-
phous powder (54.3 mg, 69%), mp: 179–180 °C. 1H NMR (ace-
tone-d6, 400 M, d): 2.72 (dd, 1H, J = 16.8, 2.4 Hz), 2.97 (d, 1H,
J = 13.2, 16.8 Hz), 3.40 (d, 2H, J = 6.4 Hz), 3.86 (s, 3H, OMe), 4.91
(dd, 1H, J = 2.0, 10.0 Hz), 4.99 (dd, 1H, J = 2.0, 16.8 Hz), 5.44 (dd,
J = 2.4, 13.2 Hz), 5.93 (m, 1H), 6.62 (d, 1H, J = 8.4 Hz), 6.99 (s, 2H),
7.07 (s, 1H), 7.61 (d, 1H, J = 8.4 Hz), 7.73 (s, 1H, OH), 9.29 (s, 1H,
OH). ESI-MS: m/z [M+H]+ 327.
4.6.13. ( )5,7-Dihydroxy-40-chloro-8-allyl-flavanone (8g)
Reagent: compound 5g (100 mg, 0.24 mmol). White amor-
phous powder (55.2 mg, 70%), mp: 157–158 °C. 1H NMR (ace-
tone-d6, 400 M, d): 2.80 (dd, 1H, J = 16.4, 2.4 Hz), 3.11 (d, 1H,
J = 12.4, 16.8 Hz), 3.30 (t, 2H, J = 6.0 Hz), 4.88 (dd, 1H, J = 2.0,
9.6 Hz), 4.96 (dd, 1H, J = 2.0, 16.8 Hz), 5.61 (dd, J = 2.4, 12.4 Hz),
5.88 (m, 1H), 6.06 (s, 1H), 7.49 (d, 2H, J = 8.0 Hz), 7.61 (d, 2H,
J = 8.0 Hz), 9.67 (s, 1H, OH), 12.11 (s, 1H, OH). ESI-MS: m/z
[M+H]+ 331.
4.6.20. ( )7-Hydroxy-8-allyl-40-chloro-flavanone (8n)
Reagent: compound 5n (100 mg, 0.28 mmol). White amorphous
powder (67.6 mg, 77%) mp: 148–150 °C. 1H NMR (CDCl3, 400 M, d):
2.81 (dd, 1H, J = 2.4, 16.8 Hz), 2.97 (dd, 1H, J = 12.8, 16.8 Hz), 3.43
(d, 1H, J = 6.0 Hz), 4.92 (dd, 1H, J = 2.0, 10.0 Hz), 5.00 (dd, 1H,
J = 2.0, 16.8 Hz), 5.60 (dd, 1H, J = 2.4, 12.8 Hz), 5.94 (m, 1H), 5.67
(d, 1H, J = 8.0 Hz), 7.50 (d, 2H, J = 8.4 Hz), 7.63 (d, 3H, J = 8.4 Hz).
ESI-MS: m/z [M+H]+ 315.
4.6.14. ( )5,7-Dihydroxy-40-methoxy-8-allyl-flavanone (8h)
Reagent: compound 5h (100 mg, 0.24 mmol). White amorphous
powder (55.9 mg, 71%), mp: 142–143 °C. 1H NMR (acetone-d6,

X. Dong et al. / Bioorg. Med. Chem. 17 (2009) 716–726
725
4.6.21. ( )40,6-Dihydroxy-8-allyl-flavanone (8o)
J = 2.0 Hz), 9.76 (s, 1H, OH), 12.82 (s, 1H, OH). ESI-MS: m/z
Reagent: compound 5o (100 mg, 0.26 mmol). White amorphous
powder (57.8 mg, 75%), mp: 176–177 °C. 1H NMR (CDCl3, 400 M,
d): 2.86 (dd, 1H, J = 2.8, 16.8 Hz), 3.01 (dd, 1H, J = 13.2, 16.8 Hz),
3.37 (d, 1H, J = 6.8 Hz), 5.06 (m, 1H), 5.10 (m, 1H), 5.36 (dd, 1H,
J = 2.8, 13.2 Hz), 5.94 (m, 1H), 6.88 (d, 2H, J = 8.4 Hz), 6.97 (d, 1H,
J = 2.8 Hz), 7.20 (d, 1H, J = 2.8 Hz), 7.35 (d, 2H, J = 8.4 Hz). ESI-MS:
m/z [M+H]+ 297.
[M+H]+ 333.
4.7.2. 7-Hydroxy-30,40-methylenedioxy-flavone (10c)
Reagent: compound 8c (100 mg, 0.21 mmol), iodine (43.7 mg,
0.21 mmol). White amorphous powder (40.5 mg, 68%), mp: 250–
253 °C. 1H NMR (acetone-d6, 400 M, d): 6.70 (s, 1H), 6.95 (dd, 1H,
J = 2.0, 8.0 Hz), 7.01 (d, 1H, J = 8.0 Hz), 7.06 (d, 1H, J = 2.0 Hz),
7.50 (dd, 1H, J = 1.6, 8.0 Hz), 7.69 (d, 1H, J = 1.6 Hz), 7.94 (d, 1H,
J = 8.0 Hz), 9.70 (s, 1H, OH). ESI-MS: m/z [M+H]+ 283.
4.6.22. ( )30,6-Dihydroxy-8-allyl-flavanone (8p)
Reagent: compound 5p (100 mg, 0.26 mmol). White amorphous
powder (60.1 mg, 78%), mp: 160–162 °C. 1H NMR (acetone-d6,
400 M, d): 2.82 (dd, 1H, J = 16.4, 3.6 Hz), 2.99 (d, 1H, J = 12.8,
16.4 Hz), 3.39 (d, 2H, J = 6.4 Hz), 5.03 (dd, 1H, J = 1.6, 10.0 Hz),
5.09 (dd, 1H, J = 1.6, 16.8 Hz), 5.47 (dd, J = 3.6, 12.8 Hz), 5.99 (m,
1H), 6.83 (dd, 1H, J = 1.6, 8.0 Hz), 6.98 (d, 1H, J = 2.4 Hz), 7.02 (d,
1H, J = 8.0 Hz), 7.07 (s, 1H), 7.14 (d, 1H, J = 2.4 Hz), 7.25 (t, 1H,
J = 8.0 Hz), 8.25 (s, 1H, OH), 8.49 (s, 1H, OH). ESI-MS: m/z [M+H]+
297.
4.7.3. 6,40-Hydroxy-8-allyl-flavone (10o)
Reagent: compound 8o (60 mg, 0.20 mmol), iodine (51.5 mg,
0.20 mmol). White amorphous powder (35.8 mg, 60%), mp: 275–
276 °C. 1H NMR (MeOH-d4, 400 M, d): 3.73 (d, 2H, J = 6.0 Hz),
5.14 (m, 1H), 5.17 (m, 1H), 6.09 (m, 1H), 6.71 (s, 1H), 6.94 (d, 2H,
J = 8.0 Hz), 7.12 (d, 1H, J = 2.8 Hz), 7.30 (d, 1H, J = 2.8 Hz), 7.87 (d,
2H, J = 8.0 Hz). ESI-MS: m/z [M+H]+ 295.
4.6.23. ( )6-Hydroxy-40-chloro-8-allyl-flavanone (8q)
Reagent: compound 5q (100 mg, 0.28 mmol). White amorphous
powder (62.3 mg, 71%), mp: 150–151 °C. 1H NMR (acetone-d6,
400 M, d): 2.85 (dd, 1H, J = 16.8, 2.8 Hz), 3.02 (d, 1H, J = 13.2,
16.8 Hz), 3.38 (d, 2H, J = 6.4 Hz), 5.03 (dd, 1H, J = 1.6, 10.0 Hz),
5.08 (dd, 1H, J = 1.6, 16.8 Hz), 5.57 (dd, J = 2.8, 13.2 Hz), 5.97 (m,
1H), 6.99 (d, 1H, J = 2.4 Hz), 7.14 (d, 1H, J = 2.4 Hz), 7.48 (d, 2H,
J = 8.4 Hz), 7.63 (d, 2H, J = 8.4 Hz), 8.28 (s, 1H, OH). ESI-MS: m/z
[M+H]+ 315.
4.8. Vasodilatory effect assay
Vascular rings were prepared from the aorta of male Male Spra-
gue-Dawley rats (four to six months old and weighing on average
250 g), and contraction studies were performed following the gen-
eral procedure detailed in the literature.19 After an equilibration
period of at least 1 h, isometric contractions induced by PE
(1 lM) were obtained. When contraction of the tissue in response
to this vasoconstrictor agent had stabilized (after about 20 min),
cumulatively increasing concentrations of the tested compounds
were added to the bath at 15–20 min intervals (the time needed
to obtain steady-state relaxation). Control tissues were simulta-
neously subjected to the same procedures, but omitting the com-
pounds and adding the vehicle. The flavonoids-induced maximal
relaxation (Emax) in aortic rings was calculated as a percentage of
4.6.24. 5,7-Dihydroxy-30-bromo-aurone (9a)
Reagent: compound 6a (100 mg, 0.24 mmol). Yellow powder
(52.2 mg, 66%), mp: 271–273 °C. 1H NMR (acetone-d6, 400 M, d):
6.17 (d, 1H, J = 1.6 Hz), 6.38 (d, 1H, J = 1.6 Hz), 6.60 (s, 1H), 7.44
(t, 1H, J = 8.0 Hz), 7.59 (m, 1H), 7.93 (d, 1H, J = 8.0 Hz), 8.13 (t,
1H, J = 2.0 Hz), 9.29 (s, 1H, OH), 9.93 (s, 1H, OH). ESI-MS: m/z
[M+H]+ 333.
the contraction in response to PE (1 lM). The half maximum effec-
tive concentration (EC50) was defined as the concentration of the
flavonoids that induced 50% of maximum relaxation from the con-
traction elicited by PE (1 lM) and was calculated from the concen-
tration–response curve by nonlinear regression (curve fit) using
GraphPad Prism (Version 4.0).
4.6.25. 5,7-Hydroxy-30,40-methylenedioxy-aurone (9b)
Reagent: compound 6b (100 mg, 0.26 mmol). White amorphous
powder (44.8 mg, 58%), mp: 275–277 °C. 1H NMR (acetone-d6,
400 M, d): 6.10 (s, 2H), 6.14 (d, 1H, J = 1.6 Hz), 6.38 (d, 1H,
J = 1.6 Hz), 6.59 (s, 1H), 6.96 (d, 1H, J = 8.0 Hz), 7.41 (1H, dd,
J = 1.6, 8.0 Hz), 7.55 (d, 1H, J = 1.6 Hz), 9.08 (s, 1H, OH), 9.83 (s,
1H, OH). ESI-MS: m/z [M+H]+ 299.
4.9. Molecular modeling and alignment
The 3D structures of all compounds were built and minimized
using SYBYL 6.9.20 The geometries of all molecules involved in this
study were optimized by Powell’s method using the tripos force
field. Conformation analyses were also carried out using the
4.7. General procedure for synthesis of compounds 10a, 10c,
10o
SYBYL/GRID search module. The lowest-energy conformations were
A stirred solution of corresponding flavanones 8a, 8c or 8o and
iodine in dry pyridine (1 mL) was heated to 90 °C for 6 h. The
mixture was cooled and poured into cold water. The precipitate
was separated and the mixture was extracted with ethyl acetate.
The combined organic phase was washed with saturated sodium
thiosulfate and water, successively. Then the organic layer was
dried with sodium sulfate and concentrated. The residue was
purified by silica gel column chromatography using petroleum
ether/ethyl acetate (5:1 ꢁ 1:1, v/v) as eluent afforded 10a, 10c
or 10o.
considered as the bioactive conformations. Compound 8q with
the most potent activity was selected as the reference molecule.
Then, all the common oxygen atoms in all skeletons of flavonoids
were selected as the atoms to superimpose all the compounds
using SYBYL/Fit-atom module.
4.10. CoMFA analysis
The steric and electrostatic fields in CoMFA were calculated
using an sp3 carbon atom with +1.0 charge as the probe atom.
The both field energies were truncated to 30 kcal/mol. And The
CoMFA fields generated automatically were scaled by the CoM-
FA-STD method. In order to investigate the effect of grid spacing,
initially the CoMFA models were developed at varying grid spacing
values (i.e., 0.5, 1.0 and 2.0 Å), and the best q2 values were obtained
when the grid spacing was set to 1.0 Å.
4.7.1. 5,7-Dihydroxy-30-bromo-flavone (10a)
Reagent: compound 8a (60 mg, 0.18 mmol), iodine (45.5 mg,
0.18 mmol). Yellow amorphous powder (41.7 mg, 70%), mp: 270–
272 °C. 1H NMR (acetone-d6, 400 M, d): 6.29 (d, 1H, J = 2.0 Hz),
6.62 (d, 1H, J = 2.0 Hz), 6.87 (s, 1H), 7.56 (t, 1H, J = 8.0 Hz), 7.79
(dd, 1H, J = 2.0, 8.0 Hz), 8.07 (d, 1H, J = 8.0 Hz), 8.25 (t, 1H,

726
X. Dong et al. / Bioorg. Med. Chem. 17 (2009) 716–726
4.11. Partial least squares (PLS) analysis
References and notes
The PLS method21 was used to set up a correlation between the
molecular fields and the pEC50 of vasorelaxant activities of tested
compounds. The optimal number of components was determined
using cross-validation (leave-one-out) method. To speed up the
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analysis and reduce noise, columns with an
r value below
2.0 kcal/mol were filtered off. The cross-validated q2 that resulted
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Contour maps were generated as a scalar product of coefficients
and standard deviation (StDev Coeff) associated with each col-
*
umn. Favored and disfavored levels, fixed at 80% and 20%, respec-
tively, were used to display the steric and the electrostatic fields.
The contours for steric fields are shown in green (more bulk fa-
vored) and yellow (less bulk favored), while the electrostatic field
contours are displayed in red (electronegative substituents fa-
vored) and blue (electropositive substituents favored) colors.
Acknowledgments
20. SYBYL Molecular Modeling System, Versions 5 and 6, TRIPOS Assoc., St. Louis,
MO, U.S.A.
21. Wold, S.; Albano, C.; Dunn, W.; Edlund, U.; Esbensen, K.; Geladi, P.; Hellberg, S.;
Johansson, E.; Lindberg, W.; Sjosstrom, M.. In Chemometrics; Kolwalski, B., Ed.;
Reidel: Dordrecht, 1987; Vol. 1, p 17.
The authors are grateful to support of National Undergraduate
Innovative Training program (NO. G2008029), and support of
School of Medicine, Zhejiang University for vasodilatory effect
assay.