Synthesis and inhibitory evaluation of cyclohexen-2-yl- and cyclohexyl-substituted phenols and quinones to endothelial cell and cancer cells

Article abstract of DOI:10.1016/j.ejmech.2010.01.051

Alkylation of phenols with 1,3-cyclohexadiene (1) has been conducted and a series of cyclohexen-2-yl- and cyclohexyl-substituted phenols and quinones were screened against the proliferation of HUVEC and cancer cells. Phenol type as well as the size and occupied position of the substitute are important for the alkylating reaction and the inhibitory activity and selectivity of a compound. 2,5-Di(cyclohexen-2-yl)benzene-1,4-diol (25) bearing two cyclohexen-2-yl groups and 2-tert-butyl-5-(cyclohexen-2-yl)benzene-1,4-diol (30) bearing cyclohexen-2-yl and tert-butyl groups exhibited good selectivity against HUVEC proliferation (IC₅₀s of 2.0 and 1.4?μM, respectively) with relatively low toxicity to ccc-HPF-1.

Full text of DOI:10.1016/j.ejmech.2010.01.051

European Journal of Medicinal Chemistry 45 (2010) 2147–2153
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and inhibitory evaluation of cyclohexen-2-yl- and
cyclohexyl-substituted phenols and quinones to endothelial cell and cancer cells
,
,
Xin Liu a d, Yingyong Ou a b, Shaopeng Chen a, Xin Lu a, Hao Cheng a, Xian Jia b, Decai Wang c,
Guo-Chun Zhou a
,d,
*
a Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, Guangdong 510663, PR China
b School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shengyang, Liaoning 110016, PR China
c School of Pharmaceutical Sciences, Nanjing University of Technology, Nanjing 210000, PR China
d Graduate School of the Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100039, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Alkylation of phenols with 1,3-cyclohexadiene (1) has been conducted and a series of cyclohexen-2-yl-
and cyclohexyl-substituted phenols and quinones were screened against the proliferation of HUVEC
and cancer cells. Phenol type as well as the size and occupied position of the substitute are important for
the alkylating reaction and the inhibitory activity and selectivity of a compound. 2,5-Di(cyclohexen-2-
yl)benzene-1,4-diol (25) bearing two cyclohexen-2-yl groups and 2-tert-butyl-5-(cyclohexen-2-yl)ben-
zene-1,4-diol (30) bearing cyclohexen-2-yl and tert-butyl groups exhibited good selectivity against
Received 30 December 2009
Received in revised form
20 January 2010
Accepted 21 January 2010
Available online 28 January 2010
HUVEC proliferation (IC50s of 2.0 and 1.4
m
M, respectively) with relatively low toxicity to ccc-HPF-1.
Keywords:
Alkylation
Ó 2010 Elsevier Masson SAS. All rights reserved.
Cyclohexen-2-yl-substituted phenol
Cyclohexen-2-yl-substituted quinone
Cell proliferation
1. Introduction
Antioxidant phenol and its counterpart quinone exist in the
opposite side of redox cycle. This reduction-oxidation feature
makes them possess a wide spectrum of biological activities
including antitumor [8–10], wound healing [11], anti-inflammatory
[12,13], antiparasitic [14,15] and cytotoxic activities [8–10]. Many
active compounds and some clinically used drugs are derivatives of
phenols or quinones and both phenol and quinone are common
building blocks for drug discovery. In this paper, we synthesized
a series of functionalized phenol and quinone products by the
reactions of different phenols with 1,3-cyclohexadiene (1) and we
present here preliminary structure-activity relationship (SAR) of
these cyclohexen-2-yl- and cyclohexyl-substituted phenols and
quinones against the proliferation of HUVEC or/and the growth of
some cancer cells.
Unregulated growth of cancer cells is the fundamental charac-
teristics of a tumor [1] and uncontrolled activation of angiogenesis
is the basal pathological process for tumor progression [2,3].
Because of these, inhibition of cancer cell growth and effective
blockage of angiogenesis are two major strategies for cancer
treatment [4,5]. Many anticancer agents and some angiogenesis
inhibitors have been used in the clinic and in recent years they have
been found to be more powerful when used in combination [5,6].
As endothelial cells play an essential role in angiogenesis [4,5,7], we
used HUVEC (human umbilical vein endothelial cell) as a target
endothelial cell to establish the preliminary screening models for
discovering potential angiogenesis inhibitors by the inhibition of
HUVEC proliferation. In another track, the inhibition for the cell
proliferation of three cancer cell lines of A549 (non-small cell lung
cancer cell line), Bel-7402 (hepatocarcinoma cell line) and MCF-7
(breast cancer cell line) was used to screen anticancer agents,
respectively.
2. Chemistry
2.1. Alkylation of phenols
The alkylating reaction was modified from the literature [16–20]
and conducted by the treatment of monohydric and dihydric
phenols with a catalytic amount of TsOH$H2O in toluene and the
alkylated products were obtained and separated in mild yields
(Schemes 1–4). As a whole, the products and reaction yields were
* Corresponding author. Guangzhou Institute of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, Guangdong 510663, PR China. Tel.: þ86 20
32290487; fax: þ86 20 32290606.
E-mail address: zhou_guochun@gibh.ac.cn (G.-C. Zhou).
0223-5234/$ – see front matter Ó 2010 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2010.01.051

2148
X. Liu et al. / European Journal of Medicinal Chemistry 45 (2010) 2147–2153
OH
OH
OH
HO
OH
HO
OH
HO
OH
1
1
+
+
60oC
38%
OH
35%
OH
5 [22]
31%
16
1
8%
20
1, 3-cyclohexadiene
1
18
19
3
1
78oC
OH
OH
OH
61%
O
O
OH
OH
1
1
16%
OH
OH
5%
O
17
75oC
37%
O
21
22
23
2
4 [21]
6 [18,19,23]
Scheme 3. Reactions of resorcins with 1,3-cyclohexadiene (1).
Scheme 1. Reactions of phenol (2) and naphthol (3) with 1,3-cyclohexadiene (1).
of Fumagillin) for HUVEC, taxol for A549 and MCF-7, or doxorubicin
for Bel-7402. The antiproliferative IC50 values for HUVEC and cancer
cell lines A549, Bel-7402 and MCF-7 are summarized in Table 1 and
preliminary structure-activity relationship (SAR) is summarized in
Fig. 1. Cytotoxicities (CC50s) of relatively active compounds
associated with the relative position of two phenolic OH groups and
the properties of substitutes. Isolable products of catechols and
resorcins were mainly in phenol form but products of p-hydro-
quinones could be in phenol form or quinone form. The sizes of
substitutes are important for the stability of substituted products
and it seems to be a rule that compounds with smaller substitutes
are more inclined to become quinones and those with larger
substitutes are stable in phenol form.
(IC50 ꢀ 15
mM to HUVEC) to human embryonic lung diploid cells
(ccc-HPF-1) [26] were also determined by the MTT method and
listed in Table 1.
Cyclohexen-2-yl-substituted phenol 4 and naphthol 5 showed
very weak activity against HUVEC proliferation. No obvious change
of inhibitory activity to HUVEC proliferation was observed from
naphthol 5 to naphthoquinone 6, but 6 had weak anticancer
activity to all tested cancer cells.
The substituted position was determined by H–H coupling in 1H
NMR spectra, which there is no obvious coupling between two
para-aromatic Hs, meanwhile, J (coupling constant) for two meta-
aromatic Hs is around 2.0 Hz and J for two ortho-aromatic Hs is
around 8.0 Hz. In addition, NOESY (DMSO-d6) of compound 30
showed that every proton of two phenolic hydroxy groups
exhibited weak NOE with only one aromatic H and methyl protons
of tert-butyl group exhibited NOE with one aromatic H. Based on
these observations, the structures of 30 and other compounds were
determined as given.
As shown in Table 1, some catechol derivatives exhibited
acceptable anti-HUVEC activity. Substitutes with a cyclohexen-2-yl
group (compounds 8, 10, 12, 13 and 15),
a methyl group
(compounds 10, 12 and 13) or a tert-butyl group (compound 15)
made the compounds weakly to moderately active against the
proliferation of HUVEC and some cancer cell lines. Two para-di-
substituted catechol derivatives of 8 and 10 were coincident with
their weak inhibitory activities against HUVEC proliferation but 8
with two cyclohexen-2-yl groups was selective for HUVEC and 10
bearing one cyclohexen-2-yl group and one methyl group was also
active against all tested cells. Importantly, with the occupation of
cyclohexen-2-yl group at the meta-position to one OH group and
the para-position to another OH groups, compound 13 obtained
good inhibitory activity against all tested cells, especially HUVEC,
A549 and Bel-7402. Compounds 12 and 15 are meta-di-substituted
2.2. Hydrogenation of active compounds
Since assay data (Table 1) showed that cyclohexen-2-yl
compounds 13, 25, 26, 30 and 31 were active against the prolifer-
ation of HUVEC or/and A549, Bel-7402 and MCF-7, double bonds of
these active compounds were hydrogenated by a general method to
afford the cyclohexyl products 34, 35 [24], 36, 37 [24,25], and 38,
respectively, for understanding the roles of cyclohexene group and
its double bond (Scheme 5).
catechol derivatives with
a common cyclohexen-2-yl group,
however, 15 with a bulky tert-butyl group was more active and
selective for HUVEC than 12 with a methyl group (Fig. 1).
Among resorcin (m-dihydric phenols) derivatives of 17, 19, 20,
22 and 23, only 20, bearing two cyclohexen-2-yl groups, showed
a very weak anti-HUVEC proliferation activity.
3. Antiproliferative activity
Compounds in this report were screened in our assay models by
the MTT method and the positive inhibitor for individual cell
proliferation was angiogenesis inhibitor TNP470 (a potent analogue
Quinones and p-hydyoquinones have their distinct SAR (Fig. 1).
p-Hydroquinone 25 with two cyclohexen-2-yl groups and 30 with
OH
OH
OH
OH
OH
HO
HO
HO
HO
HO
1
1
+
60%
34%
HO
12%
13
11
12
8
7
OH
OH
OH
OH
HO
HO
HO
1
1
62%
39%
9
10
14
15
Scheme 2. Reactions of catechols with 1,3-cyclohexadiene (1).

X. Liu et al. / European Journal of Medicinal Chemistry 45 (2010) 2147–2153
2149
OH
OH
O
O
O
O
OH
OH
1
1
+
20%
37%
25 OH
4%
24 OH
28
26
27
OH
OH
OH
OH
OH
O
OH
O
1
+
+
+
46%
4%
8%
2%
32
29
OH
30
O
33
31
Scheme 4. Reactions of p-hydroquinones with 1,3-cyclohexadiene (1).
OH
OH
OH
HO
OH
HO
85%
75%
13
34
OH
OH
35 [24]
25
O
O
OH
R2
R1
OH
92%
95%
O
O
OH
30
36 OH
R2 = cyclohexyl, 37 [24,25]
2 = tert-butyl, 38
R1 = cyclohexen-2-yl, 26
1 = tert-butyl, 31
R
R
Scheme 5. Hydrogenation of cyclohexene groups in some active compounds.
one tert-butyl group and one cyclohexen-2-yl group possessed
approximately equal activity and selectivity against HUVEC prolif-
eration, and so did their corresponding quinones 26 and 31.
However, p-hydroquinones 25 and 30 are more active than their
corresponding quinones 26 and 31. Comparison of quinone 28 with
quinones 26 and 31 made a clue that two bulky substituents were
better than one for a quinone’s activity and selectivity against
HUVEC proliferation.
Double bonds in five most active compounds were reduced and
the roles of these double bonds in antiproliferative activity are
shown in Fig. 1. Compared with their cyclohexen-2-yl p-hydroqui-
none products 13, 25, 26, 30 and 31, cyclohexyl-substituted
p-hydroquinone products 34, 35 and 36 lost part of the activity
against HUVEC proliferation; meanwhile, 34 lost the inhibitory
activity against A549 and Bel-7402 and 36’s selectivity was slightly
decreased. Cyclohexyl quinone products 37 and 38 retained the
inhibitory activity of 26 and 31 against HUVEC proliferation, but 37
gained weak activity against A549 and Bel-7402 proliferation.
There was no inhibitory difference among cyclohexane derivatives
34, 35, 36, 37 and 38 with respect to HUVEC proliferation. From
these data, we can conclude that the double bond of cyclohexen-2-
yl group was not crucial for the activity of quinones, partially
necessary for the selectivity profiles of quinones and p-hydroqui-
nones but possibly important for the anti-HUVEC activity of
p-hydroquinones.
Table 1
The IC50 values of active compounds against cell proliferation.
No. of compoundsa IC50
(
m
M)c,d
CC50
(mM)
HUVEC
A549
Bel-7402 MCF-7 ccc-HPF-1 [26]
4 [21]
5 [22]
6 [18,19,23]
8
10
12
13
15
31.5
22.0
26.7
28.8
27.1
15.3
4.7
10.0
33.0
2.0
6.2
9.1
1.4
6.8
11.6
22.4
8.3
8.2
7.4
/
/
/
/
/
/
ND
ND
ND
ND
ND
41.7
28.7
/
31.8
/
35.6
34.4
9.5
/
/
/
31.2
/
30.0
26.9
8.5
/
/
/
/
/
/
/
/
/
22.7
/
30.3
31.3
/
/
40.2
/
32.4
/
26.4
/
/
/
/
/
/
/
/
/
31.1
/
/
/
/
/
20
ND
/
/
25b
26
/
28
30.9
/
/
/
/
30b
35.3
49.4
/
ND
32.1
/
ND
/
ND
ND
ND
ND
31
32
33
34
/
27.7
/
36.3
31.9
/
/
35 [24]
36
37 [24,25]
38
TNP470
Taxol
Doxorubicin
7.8
6.0
0.0089
ND
0.0049 ND
ND 0.58
0.021
ND
ND
a
The purity of all listed compounds was determined by NMR.
The reverse-phase HPLC analyses of compounds 25 and 30 showed 95.1% and
In order to study the toxicity of these relatively active
b
compounds (IC50 ꢀ 15
mM to HUVEC) to normal cells, growth
inhibition against CCC-HPF-1, a non-cancer cell line, was measured
through the MTT assay. Results showed that the CC50 values of
97.5% in purity, respectively.
c
‘‘/’’ means IC50 or CC50 ꢁ 50
mM and ‘‘ND’’ means ‘‘Not Detected’’.
d
4 compounds of 17, 19, 22 and 23 without inhibitory activity to any of the 4 cell
these compounds to ccc-HPF-1 were higher than 28
m
M. On the
lines do not appear in the table.

2150
X. Liu et al. / European Journal of Medicinal Chemistry 45 (2010) 2147–2153
Human umbilical vein endothelial cells (HUVECs) were isolated
from freshly delivered umbilical cords and HUVECs of 3–8 passages
were used for assays; ccc-HPF-1 cell line was bought from Cell
Center of Institute of Basic Medical Sciences, Chinese Academy of
Medical Sciences; all cancer cell lines were from ATCC; FBS (Fetal
Bovine Serum) for HUVEC and ccc-HPF-1 was obtained from
Hyclone; NBCS (Newborn Calf Serum) for A549, Bel-7402 and
MCF-7 was purchased from GIBCO; EGM-2 for HUVEC was from
LONZA; RPMI 1640 for A549 and Bel-7402 and DMEM (Dulbecco’s
Modified Eagle’s Medium) for MCF-7 and ccc-HPF-1 were from
Hyclone. All cells were incubated at 37 ꢃC and 5% CO2.
O
O
OH
HO
HO
R
R
OH
R
OH
OH
Green: more bulky, more active and selective for HUVEC
Blue: reduction is allowed for HUVEC
Red: reduction is forbidden for HUVEC
Yellow: bulky group is allowed only
Pink: reduction is forbidden for HUVEC, A549 and Bel-7402
Fig. 1. Structure and activity relationship (SAR) of some phenols and quinones.
5.2. The alkylating reaction
basis of these results, it is concluded that these compounds except
12 and 13 are good selectivity for HUVEC with low toxicity to cancer
cell lines and non-cancer cell line ccc-HPF-1 and compound 13 is
selective for HUVEC, A549 and Bel-7402.
0.5–1.0 mmol of phenol was dissolved in 5–10 mL toluene under
N2 atmosphere, 1.2 equiv. of 1 and 0.1 equiv. of TsOH$H2O were
added. The reaction mixture was stirred at 75–80 ꢃC or designated
temperature and the reaction progression was monitored by TLC.
After the reaction was completed (generally 2–4 h for monohydric
phenols and 1–2 h for dihydric phenols) and volatile solvents were
evaporated, the residue was run by gradient column chromatog-
raphy (from 100% petroleum to petroleum/ethyl acetate 95:5) to
give the products.
4. Conclusions
Overall, the inhibitory activity and selectivity depended on the
combined contributions of the number and relative position of
phenolic OH groups, the occupied position and structural features
of the substitutes, and phenol form or quinone form, etc. Some
derivatives of p-hydroquinone and catechol were active against the
proliferation of HUVEC, A549, Bel-7402 and MCF-7 and their
inhibitory activity and selectivity depended on the sizes and
occupied positions of substitutes. p-Hydroquinones with a cyclo-
hexen-2-yl group generally were more active and selective
against HUVEC proliferation than their quinone counterparts.
Cyclohexen-2-yl-substituted p-hydroquinones were more active
than their cyclohexyl-substituted p-hydroquinones against HUVEC
proliferation. In addition, it is valued that catechol derivative 13
with one cyclohexen-2-yl group at the meta-position of the
phenolic OH group was active against the proliferation of HUVEC,
A549 and Bel-7402. Since this series of compounds are low toxic to
normal cell line ccc-HPF-1 and selective to HUVEC or to HUVEC,
A549 and Bel-7402, we propose here that this series of compounds
can be potential lead compounds to discover more potent and
effective angiogenesis inhibitor and/or anticancer agents.
5.2.1. 2-(Cyclohexen-2-yl)phenol (4) [21]
Starting from phenol (2); yield: 37%; colorless semisolid; 1H NMR
(CDCl3, ppm)
d
7.10 (m, 2H, aromatic H), 6.87 (t, J ¼ 7.6 Hz, 1H,
aromatic H), 6.80 (m, 1H, aromatic H), 6.06 (m, 1H, olefinic H), 5.83
(m, 1H, olefinic H), 5.31 (s, 1H, phenolic OH), 3.57 (m, 1H, Ar–CH–
C]C), 2.13 (m, 2H), 2.00 (m,1H),1.81 (m,1H),1.66 (m, 2H); 13C NMR
(CDCl3, ppm) d154.0,131.1,130.8,129.7,129.6,127.5,120.6,116.1, 38.0,
30.0, 25.0, 21.4; MS (EI): m/z 346 [2M ꢄ 2H]þ (5), 174 [M]þ (100).
5.2.2. 2-(Cyclohexen-2-yl)-1-naphthol (5) [22]
The starting material was
conducted at 60 ꢃC. Yield: 38%; brown semisolid; 1H NMR (CDCl3,
ppm)
a-naphthol (3) and the reaction was
d
8.26 (d, J ¼ 8.4 Hz, 1H, aromatic H), 7.83 (d, J ¼ 7.2 Hz, 1H,
aromatic H), 7.52 (m, 2H, aromatic H), 7.43 (d, J ¼ 8.4 Hz, 1H,
aromatic H), 7.27 (d, J ¼ 8.4 Hz,1H, aromatic H), 6.30 (s,1H, phenolic
OH), 6.24 (m, 1H, olefinic H), 6.06 (m, 1H, olefinic H), 3.66 (m, 1H,
Ar–CH–C]C), 2.40 (m, 2H), 2.12 (m, 1H), 1.94 (m, 1H), 1.70–1.90 (m,
2H); 13C NMR (CDCl3, ppm)
d 149.5, 133.5, 132.3, 129.9, 128.1, 127.5,
125.8, 125.2 (2C), 123.6, 121.6, 120.0, 39.8, 30.2, 25.1, 21.8; MS (EI):
5. Experimantal
m/z 224 [M]þ (100).
5.1. General experimental information
5.2.3. 2-(Cyclohexen-2-yl)naphthoquinone (6) [18,19,23]
The starting material was
conducted at 75–80 ꢃC; Yield: 61%; brown and amorphous semi-
solid; 1H NMR (CDCl3, ppm)
8.09 (m, 1H, aromatic H), 8.04 (m, 1H,
aromatic H), 7.71 (m, 2H, aromatic H), 6.78 (d, J ¼ 0.8 Hz, 1H,
aromatic H), 5.99 (m, 1H, olefinic H), 5.54 (m, 1H, olefinic H), 3.78
(m, 1H, Ar–CH–C]C), 2.06 (m, 3H), 1.63 (m, 2H), 1.62 (m, 1H); 13C
a-naphthol (3) and the reaction was
1H and 13C NMR spectra were recorded on a Bruker AV-400
spectrometer at 400 and 100 MHz, respectively, in CDCl3 unless
otherwise mentioned. Coupling constants (J) are expressed in hertz
d
(Hz). Chemical shifts (d) of NMR are reported in parts per million
(ppm) units relative to the solvent. The low resolution of EIMS was
recorded on a Thermo DSQ EI-mass spectrometer and the high
resolution of EIMS or FABMS was recorded on a Thermo MAT 95XP
mass spectrometer. The low or high resolution of ESIMS was
recorded on an Agilent 1200 HPLC-MSD mass spectrometer or
Applied Biosystems Q-STAR Elite ESI-LC-MS/MS mass spectrometer,
respectively. Structures of all synthetic compounds were deter-
mined by 1H NMR, 13C NMR, ESIMS, EIMS, or/and HRMS (FAB) or
HRMS (EI).
NMR (CDCl3, ppm)
d 185.4, 184.7, 154.7, 135.1, 133.6, 133.6, 132.5,
132.1, 130.8, 126.7, 126.6, 126.0, 34.1, 28.8, 24.9, 19.9; MS (EI): m/z
238 [M]þ (70), 210 [M ꢄ CO]þ (100).
5.2.4. 3,6-Di(cyclohexen-2-yl)benzene-1,2-diol (8)
Starting from catechol (7); Yield: 60%; brown and crystalline
solid; 1H NMR (CDCl3, ppm)
d 6.64 (s, 2H, aromatic H), 6.02 (m, 2H,
aromatic H), 5.82 (m, 2H, aromatic H), 5.69 (s, 1H, phenolic OH),
5.66 (s, 1H, phenolic OH), 3.59 (m, 2H, 2 ꢂ Ar–CH–C]C), 2.13 (m,
4H), 2.02 (m, 2H), 1.79 (m, 2H), 1.65 (m, 4H); 13C NMR (CDCl3, ppm)
The purity of compounds 25 and 30 was determined by reverse-
phase HPLC analysis. HPLC instrument: DIONEX SUMMIT HPLC;
Column: Diamonsil C18, 5.0
gies); detection at 210 nm by PDA-100 Photodiode Array Detector;
Elution: 67% MeOH in water; Flow rate: 1.0 mL/min.
m
m, 4.6 ꢂ 250 mm (Dikma Technolo-
d 141.9 (2C), 130.4, 130.3, 130.0, 129.9, 129.4, 129.3, 120.1 (2C), 37.4,
37.3, 30.0, 29.9, 25.1 (2C), 21.4, 21.4; MS (ESI): m/z 539 [2M ꢄ H]þ
(100), 270 [M]þ (90), 538 [2M ꢄ 2H]ꢄ (20), 269 [M ꢄ H]ꢄ (100).

X. Liu et al. / European Journal of Medicinal Chemistry 45 (2010) 2147–2153
2151
Compound 8 has two stereo-centers and it is a mixture of diaste-
5.2.10. 4-(Cyclohexen-2-yl)-2-methylbenzene-1,3-diol (19)
Starting from 2-methyl-resorcin (18); Yield: 31%; yellowish oil;
1H NMR (CDCl3, ppm)
reomers based on 1H NMR and 13C NMR.
d
6.80 (d, J ¼ 8.4 Hz, 1H, aromatic H), 6.34
5.2.5. 3-(Cyclohexen-2-yl)-6-methylbenzene-1,2-diol (10)
(d, J ¼ 8.0 Hz, 1H, aromatic H), 6.07 (m, 1H, olefinic H), 5.83 (m, 1H,
olefinic H), 5.60 (s, 1H, phenolic OH), 4.85 (s, 1H, phenolic OH), 3.43
(m, 1H, Ar–CH–C]C), 2.13 (s, 3H, CH3), 2.10–2.20 (m, 2H), 1.97 (m,
Starting from 3-methyl-catechol (9); Yield: 39%; pale brown oil;
1H NMR (CDCl3, ppm)
d
6.67 (dd, J ¼ 0.4, 8.0 Hz, 1H, aromatic H);
6.37 (d, J ¼ 8.0 Hz, 1H, aromatic H), 6.09 (m, 1H, olefinic H), 5.87 (m,
1H, oelfinic H), 5.76 (br s, 1H, phenolic OH), 5.14 (br s, 1H, phenolic
OH), 3.52 (m, 1H, Ar–CH–C]C), 2.26 (s, 3H, CH3), 2.16 (m, 2H), 2.03
1H), 1.80 (m, 1H), 1.65 (m, 2H); 13C NMR (CDCl3, ppm)
d 153.2 (2C),
131.4, 130.1, 126.8, 122.9, 111.1, 106.9, 38.8, 30.1, 25.0, 21.6, 8.1; MS
(ESI): m/z 205 [M þ H]þ (100), 203 [M ꢄ H]ꢄ (100). Coupling
(J w 8.2 Hz) exists between two adjacent aromatic Hs of 19.
(m, 1H), 1.84 (m, 1H), 1.68 (m, 2H); 13C NMR (CDCl3, ppm)
d 142.7,
141.4, 131.3, 129.9, 128.8, 122.4, 122.1, 120.2, 38.5, 30.1, 25.1, 21.5,
15.4; MS (EI): m/z 204 [M]þ (100), 189 [M ꢄ CH3]þ (20). Coupling
(J ¼ 8.0 Hz) exists between two adjacent aromatic Hs of 10.
5.2.11. 4,6-Di(cyclohexen-2-yl)-2-methylbenzene-1,3-diol (20)
Starting from 2-methyl-resorcin (18); Yield: 8%; yellowish oil;
1H NMR (CDCl3, ppm)
d
6.65 (d, J ¼ 2.8 Hz, 1H, aromatic H), 6.05 (m,
5.2.6. 3-(Cyclohexen-2-yl)-5-methylbenzene-1,2-diol (12)
2H, olefinic H), 5.84 (m, 2H, olefinic H), 5.46 (s, 1H, phenolic OH),
5.44 (s, 1H, phenolic OH), 3.41 (m, 2H, Ar–CH–C]C), 2.10–2.20 (m,
4H), 2.11 (s, 3H, CH3), 1.98 (m, 2H), 1.82 (m, 2H), 1.63 (m, 4H); 13C
Starting from 4-methyl-catechol (11); Yield: 34%; yellowish and
amorphous solid; 1H NMR (CDCl3, ppm)
d
6.60 (d, J ¼ 1.6 Hz, 1H,
aromatic H), 6.47 (d, J ¼ 1.2 Hz, 1H, aromatic H), 6.06 (m, 1H), 5.83
(m, 1H), 5.46 (s, 1H, phenolic OH), 5.27 (s, 1H, phenolic OH), 3.49
(m, 1H, Ar–CH–C]C), 2.22 (s, 3H, CH3), 2.14 (m, 2H), 2.01 (m, 1H),
NMR (CDCl3, ppm) d 151.6, 151.5, 130.3, 127.2, 127.1, 122.1, 122.0,
111.8, 111.7, 38.9, 38.8, 30.2 (2C), 25.0 (2C), 21.7 (2C), 8.3; MS (ESI):
m/z 285 [M þ H]þ (100), 283 [M ꢄ H]ꢄ (100). Compound 20 has two
stereo-centers and it is a mixture of diastereomers based on 1H
NMR and 13C NMR.
1.83 (m, 2H); 13C NMR (CDCl3, ppm)
d 144.0, 139.3, 131.2, 130.9,
130.0, 129.9, 121.4, 113.9, 38.2, 30.0, 25.0, 21.5, 20.8; MS (EI): m/z
204 [M]þ (100); HRMS (ESI): m/z 227.1046 [M þ Na]þ (100), calcd
for C13H16O2Na, 227.1048,
(J w 1.4 Hz) exists between two aromatic Hs at the meta-positions
of 12.
D
¼
ꢄ0.2 mmu. Weak coupling
5.2.12. 2-(Cyclohexen-2-yl)-5-methylbenzene-1,3-diol (22)
Starting from 5-methyl-resorcin (21); Yield: 16%; brown oil; 1H
NMR (CDCl3, ppm)
d 6.23 (s, 2H, aromatic H), 6.15 (m, 1H, olefinic
H), 5.93 (m, 1H, olefinic H), 3.96 (m, 1H, Ar–CH–C]C), 2.08 (s, 3H,
5.2.7. 4-(Cyclohexen-2-yl)-5-methylbenzene-1,2-diol (13)
CH3), 2.16 (m, 2H), 2.00 (m, 1H), 1.87 (m, 1H), 1.69 (m, 2H); 13C
Starting from 4-methyl-catechol (11); Yield: 12%; yellowish and
NMR (CDCl3, ppm) d 155.0 (2C), 137.9, 132.9, 130.3 (2C), 114.0,
amorphous solid; 1H NMR (CDCl3, ppm)
d
6.72 (s, 1H, aromatic H),
109.3, 32.0, 28.6, 25.0, 22.0, 21.0; MS (EI): m/z 205 [M þ H]þ (10),
6.67 (s, 1H, aromatic H), 6.62 (m, 1H, olefinic H), 5.89 (m, 1H,
olefinic H), 5.20 (br s, 1H, phenolic OH), 5.10 (br s, 1H, phenolic
OH), 3.50 (m, 1H, Ar–CH–C]C), 2.22 (s, 3H, CH3), 2.07 (m, 2H), 1.94
(m, 1H), 1.72 (m, 1H), 1.65 (m, 1H), 1.43 (m, 1H); 13C NMR (CDCl3,
204 [M]þ (70).
5.2.13. 5-Hydroxy-7-methylhexahydrodibenzofuran (23)
Starting from 5-methyl-resorcin (21); Yield: 5%; brown semi-
ppm)
25.0, 20.9, 18.4; MS (EI): m/z 204 [M]þ (100); HRMS (ESI): m/z
227.1044 [M
Na]þ (100), calcd for C13H16O2Na, 227.1048,
d
141.1, 137.2, 130.6, 128.4 (2C), 128.1, 117.4, 115.2, 37.2, 30.7,
solid; 1H NMR (CDCl3, ppm)
(d, J ¼ 2.0 Hz, 1H, aromatic H), 4.56 (m, 1H, Ar–O–CH), 2.96
(m, 1H, Ar–CH), 2.26 (m, 1H), 2.20 (s, 3H, CH3), 1.92 (m, 1H), 1.74
(m,1H),1.65 (m, 2H),1.52 (m,1H),1.24 (m,1H),1.12 (m,1H); 13C NMR
d
6.19 (d, J ¼ 2.0 Hz,1H, aromatic H), 6.15
þ
D
¼ ꢄ0.4 mmu. No coupling exists between two aromatic Hs at
the para-positions of 13.
(CDCl3, ppm) d 160.3,155.5,134.4,126.0,108.4, 95.68, 83.2, 39.0, 28.4,
27.5, 22.6, 20.3, 18.4; MS (EI): m/z 204 [M]þ (75). Weak coupling
(J ¼ 2.0 Hz) exists between two aromatic Hs at the meta-positions of
23. Compound 23 has two stereo-centers but it is possibly a mixture
of enantiomers [27] based on 1H NMR and 13C NMR.
5.2.8. 3-(Cyclohexen-2-yl)-5-tert-butylbenzene-1,2-diol (15)
Starting from 4-tert-butyl-catechol (14); Yield: 62%; white and
amorphous solid; 1H NMR (CDCl3, ppm)
d
6.84 (d, J ¼ 2.4 Hz, 1H,
aromatic H), 6.66 (d, J ¼ 2.0 Hz, 1H, aromatic H), 6.07 (m, 1H,
olefinic H), 5.88 (m, 1H, olefinic H), 5.55 (br s, 1H, phenolic OH),
5.34 (br s, 1H, phenolic OH), 3.51 (m, 1H, Ar–CH–C]C), 2.15 (m,
2H), 2.02 (m, 1H), 1.85 (m, 1H), 1.68 (m, 2H), 1.27 (s, 9H, C(CH3)3);
5.2.14. 2,5-Di(cyclohexen-2-yl)benzene-1,4-diol (25)
Starting from p-hydroquinone (24); Yield: 37%; white and crys-
talline solid; 1HNMR (CDCl3, ppm)
d6.58 (s, 2H, aromatic H), 6.00 (m,
13C NMR (CDCl3, ppm)
d
143.8, 139.2, 131.3, 130.4, 129.9 (2C),
2H, aromatic H), 5.76 (m, 2H, olefinic H), 4.96 (m, 2H, olefinic H), 3.50
117.8, 110.7, 39.3, 34.2, 31.5 (3C), 30.0, 25.0, 21.6; MS (EI): m/z 246
[M]þ (40), 231 [M ꢄ CH3]þ (100); HRMS (EI): m/z 246.1616 [M]þ
(m, 2H, Ar–CH–C]C), 2.10 (m, 4H),1.97 (m, 2H),1.78 (m, 2H),1.65 (m,
4H); 13C NMR (CDCl3, ppm)
d 147.4, 147.3, 130.5, 130.5, 130.1, 130.0,
(100), calcd for C16H22O2, 246.1614,
D
¼ 0.2 mmu. Weak coupling
129.6 (2C), 116.8, 116.8, 37.3, 37.2, 29.9 (2C), 25.0 (2C), 21.3, 21.3; MS
(J w 2.2 Hz) exists between two aromatic Hs at the meta-posi-
tions of 15.
(EI): m/z 270 [M]þ (100); HRMS (ESI): m/z271.1688 [M þ H]þ (70),
calcd for C18H23O2, 271.1698,
D
¼ ꢄ1.0 mmu; m/z 293.1508 [Mþ Na]þ
(100), calcd for C18H23O2, 293.1517,
D
¼ ꢄ0.9 mmu and m/z 563.3121
5.2.9. 5-Hydroxy-hexahydrodibenzofuran (17)
[2M þ Na]þ (35), calcd for C36H44NaO4, 563.3137,
D
¼ ꢄ1.6 mmu.
Starting from resorcin (16); Yield: 35%; colorless and amor-
Compound 25 has two stereo-centers and it is a mixture of diaste-
phous solid; 1H NMR (CDCl3, ppm)
d
6.97 (t, J ¼ 8.0 Hz, 1H,
reomers based on 1H NMR and 13C NMR.
aromatic H), 6.44 (d, J ¼ 7.6 Hz, 1H, aromatic H), 6.30 (dd, J ¼ 0.4,
7.6 Hz, 1H, aromatic H), 4.76 (s, 1H, phenolic OH), 4.62 (m, 1H,
Ar–O–CH), 3.20 (m, 1H, Ar–CH), 2.20 (m, 1H), 2.00 (m, 1H), 1.79 (m,
1H), 1.50–1.65 (m, 3H), 1.20–1.40 (m, 2H); 13C NMR (CDCl3, ppm)
5.2.15. 2,5-Di(cyclohexen-2-yl)-1,4-quinone (26)
Starting from p-hydroquinone (24); Yield: 4%; white and crys-
talline solid; 1H NMR (CDCl3, ppm)
d 6.54 (s, 2H, aromatic H), 5.97
d
161.1, 152.2, 128.7, 119.6, 108.0, 103.1, 82.7, 38.5, 27.6, 27.3, 22.1,
(m, 2H, olefinic H), 5.47 (m, 2H, olefinic H), 3.57 (m, 2H, Ar–CH–
20.1; MS (EI): m/z 190 [M]þ (100). Compound 17 has two stereo-
centers but it is possibly a mixture of enantiomers [27] based on
1H NMR and 13C NMR.
C]C), 2.04 (m, 4H), 1.97 (m, 2H), 1.60 (m, 4H), 1.42 (m, 2H); 13C
NMR (CDCl3, ppm)
d 187.7 (2C), 152.1 (2C), 133.2, 133.2, 130.7, 130.6,
126.5, 126.4, 33.5, 33.4, 28.7 (2C), 24.8 (2C), 19.9, 19.8; MS (EI): m/z

2152
X. Liu et al. / European Journal of Medicinal Chemistry 45 (2010) 2147–2153
268 [M]þ (100); HRMS (ESI): m/z 269.1541 [M þ H]þ (100), calcd for
5.2.20. 6-Hydroxy-7-tert-butylhexahydrodibenzofuran (33)
C18H21O2, 269.1542,
D
¼ ꢄ0.1 mmu and m/z 559.2817 [2M þ Na]þ
Starting from 2-tert-butyl p-hydroquinone (29); brown amor-
(22), calcd for C36H40O4Na, 559.2824,
D
¼ ꢄ0.7 mmu. Compound 26
phous solid; Yield: 4%; 1H NMR (CDCl3, ppm)
d 6.77 (s, 1H, aromatic
has two stereo-centers and it is a mixture of diastereomers based
on 1H NMR and 13C NMR.
H), 6.51 (s, 1H, aromatic H), 4.59 (m, 1H, Ar–O–CH), 3.10 (m, 1H,
Ar–CH), 1.96 (m, 1H), 1.80 (m, 2H), 1.58–1.20 (m, 5H), 1.38 (s, 9H,
C(CH3)3); 13C NMR (CDCl3, ppm)
d 153.3, 148.1, 135.3, 131.3, 112.2,
5.2.16. 2-(Cyclohexen-2-yl)-5-methyl-1,4-quinone (28)
108.3, 82.5, 40.9, 34.6, 29.7 (3C), 28.4, 27.6, 22.2, 20.6; MS (EI): m/z
246 [M]þ (80), 231 [M ꢄ CH3]þ (100). No coupling exists between
two aromatic Hs at the para-positions of 33.
Starting from 2-methyl p-hydroquinone (27); Yield: 20%;
yellowish and crystalline solid; 1H NMR (CDCl3, ppm)
d 6.60 (s, 1H,
aromatic H), 6.53 (s,1H, aromatic H), 5.96 (m,1H), 5.46 (m,1H), 3.57
(m, 1H, Ar–CH–C]C), 2.04 (s, 3H, CH3), 2.00–2.10 (m, 2H), 1.93 (m,
5.3. Hydrogenation of active compounds
1H), 1.63 (m, 2H), 1.40 (m, 1H); 13C NMR (CDCl3, ppm)
d 188.5, 187.3,
152.4, 145.5, 133.7, 132.8, 130.7, 126.5, 33.5, 28.7, 24.8, 19.8, 15.4; MS
0.5 mmol of olefinic compound was dissolved in 5 mL methanol
and then 0.1 equiv. of 10% Pd/C was added after evacuation of air.
The reaction was charged with H2 and stirred at room temperature
for 2 h, filtered, evaporated and purified by silica gel column
chromatography (petroleum/ethyl acetate 98:2 for quinones or
95:5 for phenols) to give the reduced product.
(EI): m/z 202 [M]þ (100); HRMS (ESI): m/z 201.0910 [M ꢄ H]þ (100),
calcd for C13H13O2, 201.0916,
D
¼ ꢄ0.6 mmu; m/z 203.1061
[M þ H]þ (70), calcd for C13H15O2, 203.1072,
D
¼ ꢄ1.1 mmu and m/z
225.0881 [M
þ
Na]þ (60), calcd for C13H14NaO2, 225.0891,
D
¼ ꢄ1.0 mmu. No coupling exists between two aromatic Hs at the
para-positions of 28.
5.3.1. 4-Cyclohexyl-5-methylbenzene-1,2-diol (34)
5.2.17. 2-tert-Butyl-5-(cyclohexen-2-yl)benzene-1,4-diol (30)
Starting from 2-tert-butyl p-hydroquinone (29); Yield: 46%;
4-(Cyclohexen-2-yl)-5-methylbenzene-1,2-diol (13); Yield:
85%; yellowish and amorphous solid; 1H NMR (CDCl3, ppm)
d 6.73
white and crystalline solid; 1H NMR (CDCl3, ppm)
d
6.74 (s, 1H,
(s, 1H, aromatic H), 6.65 (s, 1H, aromatic H), 5.60–4.70 (br s, 2H,
aromatic H), 6.46 (s, 1H, aromatic H), 6.00 (m, 1H), 5.76 (m, 1H), 5.11
(s, 1H, phenolic OH), 4.77 (s, 1H, phenolic OH), 3.49 (m, 1H, Ar–CH–
C]C), 2.10 (m, 2H), 2.00 (m, 1H), 1.77 (m, 1H), 1.62 (m, 2H), 1.38
2 ꢂ phenolic OH), 2.57 (m, 1H, Ar–CH), 2.20 (s, 3H, CH3), 1.90–1.70
(m, 5H), 1.50–1.15 (m, 5H); 13C NMR (CDCl3, ppm)
d 141.4, 140.7,
139.0,127.7,117.3,113.0, 39.7, 33.9 (2C), 27.2 (2C), 26.3,18.5; MS (EI):
(s, 9H, C(CH3)3); 1H NMR (DMSO-d6, ppm)
d
8.44 (s, 1H, phenolic
m/z 206 [M]þ (100); HRMS (ESI): m/z 229.1200 [M þ Na]þ (100),
OH), 8.38 (s,1H, phenolic OH), 6.62 (s,1H), 6.46 (s,1H), 5.83 (m, 1H),
5.57 (m, 1H), 3.59 (m, 1H, Ar–CH–C]C), 2.01 (m, 2H), 1.86 (m, 1H),
1.62 (m, 1H), 1.53 (m, 1H), 1.37 (m, 1H), 1.28 (s, 9H); NOSEY (DMSO-
d6): 8.44 (OH) with 6.46 (aromatic H), 8.36 (OH) with 6.62
(aromatic H), 6.62 (aromatic H) with 1.28 (C(CH3)3); 13C NMR
calcd for C13H18O2Na, 229.1204,
between two aromatic Hs at the para-positions of 34.
D
¼ ꢄ0.4 mmu. No coupling exists
5.3.2. 2,5-Dicyclohexylbenzene-1,4-diol (35) [24]
2,5-Di(cyclohexen-2-yl)benzene-1,4-diol (25); Yield: 75%; color-
(CDCl3, ppm)
d
147.7, 147.1, 135.2, 130.6, 129.6, 129.1, 117.4, 115.1, 37.1,
less and amorphous solid; 1H NMR (CDCl3, ppm)
d 6.59 (s, 2H,
34.3, 29.9, 29.6 (3C), 25.0, 21.3; MS (ESI): m/z 246 [M]þ (65), 231
[M ꢄ CH3]þ (100); HRMS (FAB): m/z 246.1613 [M]þ (100), calcd for
2ꢂ aromaticH), 4.32(s, 2H, 2ꢂphenolicOH), 2.72(m,2H, 2ꢂ Ar–CH),
1.84 (m, 8H),1.75 (m, 2H),1.43 (m, 8H),1.27 (m, 2H); 13C NMR (CDCl3,
C16H22O2, 246.1614,
two aromatic Hs at the para-positions of 30.
D
¼ ꢄ0.1 mmu. No coupling exists between
ppm) d 146.6 (2C),131.6 (2C),113.8 (2C), 50.9 (2C), 37.1 (2C), 33.2 (2C),
27.0 (4C), 26.3 (2C); MS (ESI): m/z 547 [2M ꢄ H]þ (35), 274 [M]þ (25),
273 [M ꢄ H]þ (100). As compound 25, compound 35 has two stereo-
5.2.18. 2-tert-Butyl-5-(cyclohexen-2-yl)-1,4-quinone (31)
centers and it is a mixture of diastereomers based on 1H NMR and 13
NMR.
C
Starting from 2-tert-butyl p-hydroquinone (29); Yield: 8%;
yellowish oil; 1H NMR (CDCl3, ppm)
d 6.57 (s, 1H, aromatic H),
6.44 (s, 1H, aromatic H), 5.95 (m, 1H), 5.46 (m, 1H), 3.54 (m, 1H,
5.3.3. 2-tert-Butyl-5-cyclohexylbenzene-1,4-diol (36)
Ar–CH–C]C), 2.03 (m, 2H), 1.96 (m, 1H), 1.58 (m, 2H), 1.42 (m,
2-tert-Butyl-5-(cyclohexen-2-yl)benzene-1,4-diol (30); Yield:
1H), 1.28 (s, 9H, C(CH3)3); 13C NMR (CDCl3, ppm)
d
188.2, 188.1,
95%; colorless and amorphous solid; 1H NMR (CDCl3, ppm)
d
6.68
155.7, 150.6, 134.9, 131.9, 130.6, 126.5, 35.0, 33.2, 29.2 (3C), 28.6,
24.9, 19.9; MS (EI): m/z 244 [M]þ (85), 229 [M ꢄ CH3]þ (100);
HRMS (ESI): m/z 245.1542 [M þ H]þ (100), calcd for C16H21O2,
(s, 1H, aromatic H), 6.48 (s, 1H, aromatic H), 4.40 (s, 1H, phenolic
OH), 4.30 (s, 1H, phenolic OH), 2.70 (m, 1H, Ar–CH), 1.85 (m, 4H),
1.74 (m, 1H), 1.50–1.20 (m, 5H), 1.37 (s, 9H, C(CH3)3); 1H NMR
245.1542,
D
¼
ꢄ0.0 mmu and HRMS (ESI): m/z 267.1357
(CDCl3 þ D2O, ppm)
H), 2.70 (m, 1H, Ar–CH), 1.84 (m, 4H), 1.76 (m, 1H), 1.50–1.20 (m,
5H), 1.37 (s, 9H, C(CH3)3); 13C NMR (CDCl3, ppm)
147.9, 145.9,
d 6.68 (s, 1H, aromatic H), 6.48 (s, 1H, aromatic
[M þ Na]þ (75), calcd for C16H20NaO2, 267.1361,
D
¼ ꢄ0.4 mmu.
No coupling exists between two aromatic Hs at the para-posi-
tions of 31.
d
134.1, 131.6, 115.0, 114.3, 37.0, 34.2, 33.1 (2C), 29.6 (2C), 26.9, 26.3;
MS (EI): m/z 248 [M]þ (55), 233 [M ꢄ CH3]þ (100); HRMS (EI): m/z
5.2.19. 2-tert-Butyl-6-(cyclohexen-2-yl)benzene-1,4-diol (32)
Starting from 2-tert-butyl p-hydroquinone (29); Yield: 2%;
248.1772 [M]þ (100), calcd for C22H26O4, 248.1771,
No coupling exists between two aromatic Hs at the para-positions
of 36.
D
¼ 0.1 mmu.
brown oil; 1H NMR (CDCl3, ppm)
d
6.67 (d, J ¼ 3.2 Hz, 1H, aromatic
H), 6.48 (d, J ¼ 2.8 Hz, 1H, aromatic H), 6.08 (m, 1H, olefinic H), 5.82
(m, 1H, olefinic H), 5.24 (s, 1H, phenolic OH), 4.36 (s, 1H, phenolic
OH), 3.40 (m, 1H, Ar–CH–C]C), 2.14 (m, 2H), 1.96 (m, 1H), 1.82 (m,
1H), 1.78–1.60 (m, 2H), 1.38 (s, 9H, C(CH3)3); 13C NMR (CDCl3, ppm)
5.3.4. 2,5-Dicyclohexyl-1,4-quinone (37) [24,25]
2,5-Di(cyclohexen-2-yl)-1,4-quinone (26); Yield: 92%; colorless
and amorphous solid; 1H NMR (CDCl3, ppm)
d
6.46 (s, 2H,
2 ꢂ aromatic H), 2.67 (m, 2H, 2 ꢂ Ar–CH), 1.90–1.70 (m, 10H), 1.56–
1.30 (m, 4H), 1.26–1.08 (m,6H); 13C NMR (CDCl3, ppm)
188.0 (2C),
d
148.2, 147.0, 138.3, 131.9, 131.6, 129.5, 113.8, 112.4, 39.6, 34.8, 29.7
(3C), 29.5, 24.9, 21.6; MS (EI): m/z 246 [M]þ (50), 229 [M ꢄ CH3]þ
d
(65), 163 [M ꢄ C6H11
]
þ (100); HRMS (EI): m/z 246.1615 [M]þ (100),
153.3 (2C), 131.2 (2C), 36.1 (2C), 32.1 (4C), 26.3 (4C), 26.0 (2C); MS
(EI): m/z 272 [M]þ (60). As compound 26, compound 37 has two
stereo-centers and it is a mixture of diastereomers based on 1H
NMR and 13C NMR.
calcd for C16H22O2, 246.1614,
D
¼ 0.1 mmu. Weak coupling
(J w 3.0 Hz) exists between two aromatic Hs at the meta-positions
of 32.

X. Liu et al. / European Journal of Medicinal Chemistry 45 (2010) 2147–2153
2153
5.3.5. 2-tert-Butyl-5-cyclohexyl-1,4-quinone (38)
Traditional Chinese Medicine of Guangdong Province of China
(2007202). We are thankful to Mr. Yingxue Liu for his technical help
with HPLC analysis.
2-tert-Butyl-5-(cyclohexen-2-yl)-1,4-quinone (31); Yield: 92%;
yellowish and crystalline solid; 1H NMR (CDCl3, ppm)
d
6.56 (s, 1H,
aromatic H), 6.39 (d, J ¼ 0.8 Hz,1H, aromatic H), 2.65 (m,1H, Ar–CH),
1.80 (m, 5H),1.40 (m, 2H),1.27 (s, 9H, C(CH3)3),1.27–1.10 (m, 3H); 13
C
References
NMR (CDCl3, ppm) d 188.4,188.3,155.3,152.2,132.9,132.0, 35.8, 35.0,
32.0 (2C), 29.2 (3C), 26.3 (2C), 26.0; MS (EI): m/z 246 [M]þ (55);
HRMS (EI): m/z 246.1610 [M]þ (100), calcd for C16H22O2, 246.1614,
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D
¼ ꢄ0.4 mmu; HRMS (ESI): m/z 247.1690 [M þ H]þ (60), calcd for
C16H23O2, 247.1698,
(100), calcd for C16H22O2Na, 269.1517,
exists between two aromatic Hs at the para-positions of 38.
D
¼ ꢄ0.8 mmu and m/z 269.1518 [M þ Na]þ
D
¼ 0.1 mmu. No coupling
5.4. Experimental procedure for assay
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The activities of target compounds against the proliferation of
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1000 cells/well of HUVEC and Bel-7402 or 1500 cells/well of MCF-7
and ccc-HPF-1 or 2000 cells/well of A549 in 190
medium were seeded in 96-well plates and allowed to attach or
stabilize for 20 h before being treated with 10 L stock solutions of
mL corresponding
m
different concentration of a compound or carrier. Every concen-
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Acknowledgements
This work was supported by the Knowledge Innovation Program
of Chinese Academy of Sciences (KSCX-2-YW-R-22), Natural
Science Foundation of China (30973621) and Administration of