Synthesis and biological evaluation of bilobol and adipostatin A

Article abstract of DOI:10.1080/10286020.2011.554828

Concise total synthesis of bilobol 5-pentadecenylresorcinol (1), isolated from Gingko biloba fruits, has been achieved in 10 steps with 51% overall yield from 3,5-dihydroxybenzoic acid (3). Adipostatin A (2), isolated from the fruits as well as from Streptomyces cyaneus 2299-SV1, has also been synthesized in two steps from methylated bilobol (10). The structure-activity relationship study of synthetic products was described by means of cytotoxic assay against human KB carcinoma cell lines.

Full text of DOI:10.1080/10286020.2011.554828

This article was downloaded by: [UNAM Ciudad Universitaria]
On: 05 January 2015, At: 00:31
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Journal of Asian Natural Products
Research
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/ganp20
Synthesis and biological evaluation of
bilobol and adipostatin A
Ayano Tanaka a , Yasuhiro Arai a , Su-Nam Kim b , Jungyeob Ham b
& Toyonobu Usuki a
a Department of Materials & Life Sciences , Faculty of Science &
Technology, Sophia University , 7-1 Kioicho, Chiyoda-Ku, Tokyo,
102-8554, Japan
b Natural Products Research Center, Korea Institute of Science and
Technology , 290 Daejeon-Dong, Gangneung, 210-340, South Korea
Published online: 30 Mar 2011.
To cite this article: Ayano Tanaka , Yasuhiro Arai , Su-Nam Kim , Jungyeob Ham & Toyonobu Usuki
(2011) Synthesis and biological evaluation of bilobol and adipostatin A, Journal of Asian Natural
Products Research, 13:04, 290-296, DOI: 10.1080/10286020.2011.554828
To link to this article: http://dx.doi.org/10.1080/10286020.2011.554828
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the
“Content”) contained in the publications on our platform. However, Taylor & Francis,
our agents, and our licensors make no representations or warranties whatsoever as to
the accuracy, completeness, or suitability for any purpose of the Content. Any opinions
and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content
should not be relied upon and should be independently verified with primary sources
of information. Taylor and Francis shall not be liable for any losses, actions, claims,
proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or
howsoever caused arising directly or indirectly in connection with, in relation to or arising
out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

Conditions of access and use can be found at http://www.tandfonline.com/page/terms-
and-conditions

Journal of Asian Natural Products Research
Vol. 13, No. 4, April 2011, 290–296
Synthesis and biological evaluation of bilobol and adipostatin A
Ayano Tanakaa, Yasuhiro Araia, Su-Nam Kimb, Jungyeob Hamb and Toyonobu Usukia*
aDepartment of Materials & Life Sciences, Faculty of Science & Technology, Sophia University, 7-1
Kioicho, Chiyoda-Ku, Tokyo 102-8554, Japan; bNatural Products Research Center, Korea Institute
of Science and Technology, 290 Daejeon-Dong, Gangneung 210-340, South Korea
(Received 22 November 2010; final version received 11 January 2011)
This paper is dedicated to Prof. Koji Nakanishi on the occasion of his 85th birthday
Concise total synthesis of bilobol 5-pentadecenylresorcinol (1), isolated from Gingko
biloba fruits, has been achieved in 10 steps with 51% overall yield from 3,5-
dihydroxybenzoic acid (3). Adipostatin A (2), isolated from the fruits as well as from
Streptomyces cyaneus 2299-SV1, has also been synthesized in two steps from
methylated bilobol (10). The structure–activity relationship study of synthetic products
was described by means of cytotoxic assay against human KB carcinoma cell lines.
Keywords: bilobol; adipostatin A; total synthesis; cytotoxicity; structure–activity
relationship
1. Introduction
bilobol 5-pentadecenylresorcinol (1,
Figure 1), isolated from some plants such
as Gingko biloba fruits [10,11], is well
known. It was found that an increase in the
number of double bonds in the side chain
of 1 enhanced the biological activities,
such as cytotoxicity, antibacterial activity,
and inhibitory activity for tyrosinase
[6–8]. However, the distinction of alkane,
alkene, and alkyne moieties in the side
chain for the biological activity of
resorcinols has been unknown.
More than 100 species of 5-alk(en)ylre-
sorcinols have been isolated from higher
plant families, algae, mosses, fungi, and
several bacterial families as secondary
metabolites [1]. The natural products
comprise homologous 1,3-dihydroxyben-
zenes with 5-alk(en)yl side chains from C5
to C29, structurally related monoenes,
dienes, and trienes in Z configurations.
The side chain on resorcinols in most cases
is odd numbered, which is significant with
regard to their biosynthetic pathway.
Interest in such attractive biological
aspects and in the understanding of
the structure–activity relationship of 5-
alk(en)ylresorcinols prompted us to con-
duct a study of efficient synthesis and
biological assay. Among the numerous
papers of synthetic study of 5-alk(en)ylre-
sorcinols [3,6,12–16], one of the previous
synthesis of 1 was reported by Hecht and
co-workers [3] with 27% overall yield in
Alk(en)ylresorcinols have been recog-
nized to exert numerous biological qual-
ities such as DNA cleavaging [2,3], tumor
promoting activity [4], cytotoxicity toward
HaCaT cell lines [5], KB cell lines [6],
antibacterial activity [7], inhibitory
activity for tyrosinase [8], and inhibition
to HIV-1 protease [9]. As a remarkable
molecule among the resorcinol family,
*Corresponding author. Email: t-usuki@sophia.ac.jp
ISSN 1028-6020 print/ISSN 1477-2213 online
q 2011 Taylor & Francis
DOI: 10.1080/10286020.2011.554828
http://www.informaworld.com

Journal of Asian Natural Products Research
291
alcohol 7 by H2 with Pd/C in 97% yield,
followed by Appel reaction to give
bromide 8 in 98% yield. Coupling with
lithium acetylide of 1-octyne gave alkyne
9 in the presence of tetrabutylammonium
iodide (TBAI) [21]. Alkyne 9 was
quantitatively hydrogenated to give Z-
selective alkene 10 by Lindlar catalyst
with a drop of quinoline. Finally, removal
of methyl groups of 10 gave desired
bilobol 1 in 93% yield using methylmag-
nesium iodide at 1708C [22]. Synthetic 1
was identical in all respects (1H, 13C NMR,
MS) with authentic data [3]. Thus, total
synthesis of bilobol 1 was achieved with
overall 51% yield in 10 steps.
Figure 1. Structures of bilobol (1) and
adipostatin A (2).
eight steps from 3,5-dimethoxybenzalde-
hyde. In this paper, synthesis and KB cell
cytotoxicity assay of resorcinols are
described. Target molecules include unna-
tural analogs of bilobol 1 as well as 5-
pentadecylresorcinol adipostatin A (2,
Figure 1), which is isolated not only from
Ginkgo fruits but also from Streptomyces
cyaneus 2299-SV1 [17].
Direct hydrogenation of bilobol 1 by
Pd/C did not undergo toward natural
adipostatin A 2. Then, hydrogenation of
methylated bilobol 10 was quantitatively
succeeded, and following deprotection of
methyl groups by methylmagnesium iod-
ide without solvents at 1708C in 95% yield
gave the desired 2. Thus, total synthesis of
2 was also achieved as well. Meanwhile,
for the structure–activity relationship
study of the resorcinols, removal of methyl
groups of synthetic intermediates 7 and 9
was carried out under the same conditions,
respectively. Synthetic unnatural analogs
12 and 11 with free phenols were thereby
obtained (Scheme 1).
2. Results and discussion
As shown in Scheme 1, synthesis of 1 and
2 in this research involved Appel reaction,
Wittig reaction, alkyne coupling reaction,
and Lindlar reduction, beginning with 3,5-
dihydroxybenzoic acid (3). Treatment of 3
with potassium carbonate followed by
dimethyl sulfate under reflux condition for
4 h gave a trimethyl product in 91% yield
[18], and reduction of methyl ester with
lithium aluminum hydride (LAH) gave
alcohol 4 in 92% yield [19]. Alcohol 4 was
then converted to bromide 5 with Appel
reaction in 98% yield by using triphenyl-
phosphine and carbon tetrabromide. The
obtained 5 was transformed into the
corresponding phosphonium salt, followed
by deprotonation with n-BuLi for Wittig
reaction. 1.1 equivalent of the resulting
benzyl phosphorus ylide was reacted with
6-benzyloxy-1-hexanal, which was led
from 1,6-hexanediol [20]. The Wittig
reaction gave 6 in 87% yield in two
steps. The ratio of E/Z configuration of
Five synthetic samples 1, 2, and 10–12
were tested for the biological activity
by inhibiting proliferation on human
carcinoma KB cell lines utilized by
3-(4,5-dimethylthiazol-2-yl)-5-(3-carbox-
ymethoxyphenyl)-2-(4-sulfophenyl)-2H-
tetrazolium, inner salt (MTS) method
(Table 1). Both 10, which is not a free
phenol group, and 12, which has a shorter
alkyl chain with free terminal alcohol,
were inactive. Interestingly, compound 11,
which has an alkyne moiety in the side
chain, showed cytotoxic activities with
IC50 value of 14.0 mM, whereas bilobol 1
and adipostatin A 2 exerted IC50 values of
14.3 and 10.6 mM, respectively. Other
biological tests such as anti-obesity and
1
olefin 6 was determined to be 3/2 by H
NMR analysis. Hydrogenation of 6 gave

292
A. Tanaka et al.

Journal of Asian Natural Products Research
3.2 Synthetic procedures
3.2.1 1,3-Dimethoxy-5-hydroxymethyl-
293
Table 1. Cytotoxicity against KB cell lines.
Synthetic products
IC50 (mM)
benzene (4)
Bilobol 1
Adipostatin A 2
14.3
10.6
To a solution of 3,5-dihydroxybenzoic
acid 3 (3.08 g, 20.0 mmol) and K2CO3
(11.1 g, 80.0 mmol) in acetone (30.8 ml),
dimethyl sulfate (6.64 ml, 70.0 mmol) was
added at room temperature. The reaction
mixture was vigorously stirred at reflux for
4 h, and filtered. The filter solid was rinsed
with acetone, and most of acetone was
removed. The residue was diluted with
saturated aqueous NaHCO3 (15 ml), stirred
for 5 min, and extracted with EtOAc
(3 £ 20 ml). The organic layer was washed
with aqueous 5% HCl, then with saturated
aqueous NaHCO3, and dried over Na2SO4.
Concentration and flash column chroma-
tography (hexane:EtOAc ¼ 8:1) gave 3,5-
dimethoxybenzoic acid methyl ester
(3.57 g, 18.2 mmol, 91%): white powder;
C10H12O4, mp 42–448C; IR (KBr): nmax
3017, 2959, 1721, 1599, 1458, 1427, 1301,
1244, 1208, 1158, 1102, 1052, 930, 886,
Alkyne-type bilobol 11
Methylated bilobol 10
5-(7-Hydroxyheptyl)resorcinol 12
14.0
.100
.100
diabetes using peroxisome proliferator-
activated receptor’s cell-based assays
showed no activity (data not shown).
In summary, we have achieved the total
synthesis of bilobol 1 with overall 51%
yield in 10 steps. Meanwhile natural
adipostatin A 2 and the related unnatural
5-resorcinol derivatives were successfully
synthesized. Three properties upon the
cytotoxicity assay against KB cell lines
were found by means of the structure
activity–relationship study. First, the com-
pound which has short carbon chain length
with terminal hydroxyl groups is not
cytotoxic. Second, it is important to have
free phenol groups to exert cytotoxicity.
Third, alkane, alkene, and alkyne moieties
in C15 chains at 5-position of resorcinols do
not affect IC50 values.
846, 762, 675, 627, 549, 442 cm21 1H
;
NMR (300 MHz, CDCl3) d 7.19 (2H, d,
J ¼ 2.4 Hz, Ar), 6.65 (1H, t, J ¼ 2.4 Hz,
Ar), 3.91 (3H, s, COOMe), 3.83 (6H, s,
OMe); EI-MS m/z 196 [M]þ.
To
a solution of LAH (1.03 g,
3. Experimental
27.2mmol) in THF (22 ml), 3,5-dimethoxy-
benzoic acid methyl ester (3.56 g,
18.2 mmol) in dry THF (50 ml) was slowly
added at 08C for 10 min. After being
stirred at room temperature for 2 h, the
mixture was cooled to 08C, and the
reaction quenched with H2O (40 ml). The
mixture was acidified to pH 4–5 with
aqueous 2 N HCl, and then filtered through
Celite. The filtrate was extracted with
EtOAc (4 £ 50 ml). The organic layer was
washed with brine and dried over Na2SO4.
Concentration and flash column chroma-
tography (hexane:EtOAc ¼ 4:1) gave pro-
duct 4 (2.80 g, 16.6 mmol, 92%): white
powder; C9H12O3, mp 48–508C; IR (KBr)
3.1 General experimental procedures
Melting point was measured by an AS one
ATM-01 apparatus. Infrared (IR) spectra
were measured with a JASCO FT-IR 4100
spectrometer. 1H and 13C NMR spectra
were recorded on a JEOL Lambda 300
spectrometer in deuterium solvents using
CHCl3 or MeOH as an internal standard.
EI-MS spectra were recorded on a
Shimadzu GCMS QP-5050 instrument.
ESI-MS spectra were recorded on a JEOL
JMS-T100LC instrument or on a Thermo
Exactive spectrometer. Tetrahydrofuran
(THF), dichloromethane (CH2Cl2), ben-
zene, and diethyl ether (Et2O) were dried
over molecular sieves. Other solvents were
used without further purification.
nmax: 3398, 3008, 2930, 1600, 1458, 1363,
1295, 1207, 1065, 1011, 914, 864, 828,

294
A. Tanaka et al.
1
702 cm21; H NMR (300 MHz, CDCl3) d
6.53 (2H, d, J ¼ 2.4 Hz, Ar), 6.39 (1H, t,
J ¼ 2.4 Hz, Ar), 4.64 (2H, s, CH2), 3.80
(6H, s, OMe); EI-MS m/z 168 [M]þ.
Et2O (3 £ 30 ml). The organic layer was
washed with brine and dried over Na2SO4.
On concentration and flash column chro-
matography (hexane:EtOAc ¼ 8:1) it gave
product 6 (1.42 g, 4.17 mmol, 87%):
colorless oil; IR (neat): nmax 2934, 2855,
1592, 1456, 1425, 1360, 1204, 1154, 1065,
3.2.2 5-Bromomethyl-1,3-dimethoxy-
benzene (5)
966, 833, 737, 698 cm21
;
1H NMR
To a solution of 4 (1.91 g, 11.3 mmol) in
dry CH2Cl2 (46 ml), triphenylphosphine
(5.95 g, 22.6 mmol) was added at room
temperature. After being stirred for
10 min, carbon tetrabromide (7.52 g,
22.6 mmol) was added at 2788C, and
was stirred at 2508C for 80 min. The
reaction mixture was treated with hexane–
EtOAc mixture (20 ml) and passed
through flash short column chromatog-
raphy (EtOAc 300 ml). Concentration
and flash column chromatography
(hexane:EtOAc ¼ 20:1) gave product 5
(2.57 g, 11.1 mmol, 98%): white powder;
C9H11BrO3, mp 73–758C; IR (KBr): nmax
3060, 3003, 2936, 2837, 1721, 1595, 1477,
1331, 1167, 1069, 941, 853, 822, 697, 646,
(300 MHz, CDCl3) d 7.34–7.29 (5H, m,
Ar), 6.50–6.42 (2H, m, Bn), 6.35 (2H, d,
J ¼ 2.1 Hz, Ar), 6.33 (1H, t, J ¼ 2.1 Hz,
Ar), 4.50–4.49 (2H, m, OCH2Ar), 3.79
(6H, s, OMe), 3.50–3.43 (2H, dd, J ¼ 6.6,
6.6 Hz, CH2OBn), 2.35–2.17 (2H, m,
CHCH2), 1.67–1.41 (6H, m, CH2); HR-
ESI-MS: m/z 363.1915 [M þ Na]þ (calcd
for C22H28O3Na, 363.1931).
3.2.4 1,3-Dimethoxy-5-(70-hydroxyheptyl)-
benzene (7)
A mixture of 6 (216 mg, 0.63 mmol) and
10% Pd/C (51.4 mg) in dry THF (5 ml) was
stirred under H2 for 50 h. The reaction
mixture was passed through short flash
column chromatography (Et2O, 200 ml).
On concentration and flash column chro-
matography (hexane:EtOAc ¼ 3:1) it gave
product 7 (156 mg, 0.62 mmol, 97%):
colorless oil; data, see Reference [3].
1
608, 526, 475 cm21; H NMR (300 MHz,
CDCl3) d 6.54 (2H, d, J ¼ 2.4 Hz, Ar),
6.40–6.39 (1H, t, J ¼ 2.4 Hz, Ar), 4.42
(2H, s, CH2Br), 3.80 (6H, s, OMe); 13C
NMR (75 MHz, CDCl3) d 161.1, 139.9,
107.1, 100.8, 55.5, 33.8; EI-MS m/z
230 [M]þ.
3.2.5 5-(70-Bromoheptyl)-1,3-dimethoxy-
benzene (8), 1,3-dimethoxy-5-(80-penta-
decyn-1-yl)benzene (9), and 1,3-dimethoxy-
5-[80(Z)-pentadecen-1-yl]benzene (10)
3.2.3 1,3-Dimethoxy-5-(70-benzyloxy-1-
heptenyl)benzene (6)
A mixture of 5 (1.16 g, 5.0 mmol) and
triphenylphosphine (1.31 g, 5.0 mmol) in
distilled benzene (10 ml) was stirred under
reflux for 5 h, and on concentration gave
phosphonium salt as product. A solution of
the obtained crude salt in dry THF (25 ml)
at 08C was added dropwise to 2.6 M n-
BuLi in hexane (1.93 ml, 5.02 mmol).
After being stirred for 15 min at 08C, 6-
benzyloxy-1-hexanal (0.93 ml, 4.5 mmol)
was added. After stirring for 3 h at room
temperature, the reaction was quenched
with ice water (15 ml), and extracted with
See Reference [3].
3.2.6 1,3-Dihydroxy-5-[80(Z)-penta-
decenyl]benzene (1)
To a solution of 10 (79.9 mg, 0.23 mmol)
in dry Et2O (1 ml), 0.94 M of MeMgI
(4.9 ml, 0.46 mmol) in Et2O was added at
08C. After the mixture was heated to
1008C in vacuo, the residue was heated at
1708C for 1 h under N2. The cooled
reaction mixture was quenched with
saturated aqueous NH4Cl (10 ml), and

Journal of Asian Natural Products Research
295
extracted with EtOAc (4 £ 20 ml).
The organic layer was washed with brine,
and dried over Na2SO4. On concentration
and flash column chromatography
(hexane:EtOAc ¼ 5:1) it gave product 1
(68.0 mg, 0.21mmol, 93%): yellow oil; IR
(neat) nmax: 3356, 2925, 2854, 1599, 1466,
1339, 1154, 995, 837, 694 cm21; 1H NMR
0.94 M of MeMgI (7.5 ml, 7.04 mmol) in
Et2O was added at 08C. After the mixture
was heated to 1008C in vacuo, the residue
was then heated at 1708C for 1 h under N2.
The cooled reaction mixture was quenched
with saturated aqueous NH4Cl (10 ml), and
extracted with EtOAc (4 £ 20 ml). The
organic layer was washed with brine and
dried over Na2SO4. Flash column chroma-
tography (hexane:EtOAc ¼ 4:1) gave pro-
duct 2 (107 mg, 0.34 mmol, 95%): white
powder; mp 85–878C; IR (KBr): nmax
3323, 2916, 2847, 1607, 1512, 1469, 1331,
(300 MHz, CDCl3)
d 6.24 (2H, d,
J ¼ 1.8 Hz, Ar), 6.17 (1H, t, J ¼ 1.8 Hz,
Ar), 5.38–5.32 (2H, m, CHvCH), 4.63
(2H, s, OH), 2.48 (2H, t, J ¼ 7.8 Hz,
ArCH2), 2.02–2.00 (4H, m, CH2-
CHvCHCH2), 1.57 (2H, m, ArCH2CH2),
1.30–1.24 (16H, m, CH2), 0.88 (3H, t,
J ¼ 6.5 Hz, CH3); 13C NMR (75 MHz,
CDCl3) d 156.3, 145.9, 129.7, 129.6,
107.8, 99.8, 35.5, 31.5, 30.8, 29.5, 29.1,
29.0, 28.9, 28.7, 27.0, 26.9, 22.4, 13.9; HR-
ESI-MS: m/z 363.1915 [M þ Na]þ (calcd
for C21H34O2, 363.1931), 318.2538 [M]þ
(calcd for C21H34O2, 318.2559).
1200, 1146, 991, 830, 721, 697, 569 cm21
;
1H NMR (300 MHz, CD3OD) d 6.12 (2H,
d, J ¼ 2.4 Hz, Ar), 6.07 (1H, t, J ¼ 2.4 Hz,
Ar), 2.46–2.40 (2H, m, ArCH2), 1.55 (2H,
m, ArCH2CH2), 1.28 (24H, m, CH2),
0.91–0.87 (3H, m, CH3); 13C NMR
(75 MHz, CD3OD) d 159.2, 159.1, 146.3,
108.0, 107.9, 101.0, 100.9, 37.1, 37.0,
33.2, 33.1, 32.5, 30.9, 30.9, 30.8, 30.6,
30.6, 30.5, 30.5, 30.4, 23.2, 23.7, 14.7,
14.5; HR-EI-MS: m/z 320.2713 [M]þ
(calcd for C21H36O2, 320.2715).
3.2.7 1,3-Dihydroxy-5-pentadecyl-
benzene
A mixture of 1,3-dimethoxy-5-[80(Z)-pen-
3.2.8 1,3-Dihydroxy-5-(70-hydroxyheptyl)-
benzene (12)
tadecen-1-yl]benzene
10
(0.21 g,
0.61 mmol) and 10% Pd/C (50 mg) in 5 ml
of dry THF was stirred under H2 for 18 h.
The reaction mixture was passed through a
short column of silica gel and eluted with
EtOAc (150 ml). On concentration it
gave 1,3-dimethoxy-5-pentadecylbenzene
(215 mg, 0.67 mmol) in quant.: white
Yield 89%: white powder; mp: 123–1258C;
IR (KBr): nmax 3420, 3256, 2939, 2855,
2536, 2422, 2277, 1595, 1464, 1336, 1161,
1065, 1036, 925, 856, 836, 698, 582,
523 cm21; 1H NMR (300MHz, CD3OD) d
6.11 (2H, d, J ¼ 2.4 Hz, Ar), 6.07 (1H, t,
J ¼ 2.4 Hz, Ar), 3.52 (2H, t, J ¼ 6.6 Hz,
CH2OH), 2.43 (2H, t, J ¼ 7.5 Hz, ArCH2),
1.60–1.51(4H,m,CH2),1.34(6H,m,CH2);
13C NMR (75 MHz, CD3OD) d 159.3,
146.3, 107.9, 101.0, 63.0, 37.0, 33.6, 32.4,
30.4, 30.3, 26.9; HR-EI-MS: m/z 224.1411
[M]þ (calcd for C13H20O3, 224.1412).
powder; mp 49–518C; IR (KBr) nmax
2917, 2849, 1599, 1346, 1293, 1206, 1151,
1056, 842, 821, 696 cm21 1H NMR
:
;
(300 MHz, CDCl3) d 6.34 (2H, s, Ar),
6.30 (1H, s, Ar), 3.78 (6H, s, OMe), 2.54
(2H, t, J ¼ 7.8 Hz, ArCH2), 1.60–1.55
(2H, m, ArCH2CH2), 1.25 (24H, m, CH2),
0.88 (3H, t, J ¼ 6.0 Hz, CH3); 13C NMR
(75 MHz, CDCl3), d 160.9, 145.7, 106.8,
106.7, 97.8, 55.4, 36.6, 32.2, 31.6, 30.0,
29.9, 29.8, 29.7, 29.6, 22.9, 14.4.
3.2.9 1,3-Dihydroxy-5-(80-pentadecynyl)-
benzene (11)
To a solution of 1,3-dimethoxy-5-
pentadecylbenzene (0.123 g, 0.35 mmol)
in dry Et2O (1.5 ml) and dry THF (0.1 ml),
Yield 80%: colorless oil; IR (neat) nmax
3388, 2929, 2856, 1706, 1602, 1466, 1336,
1155, 998, 838, 695 cm21 1H NMR
:
;

296
A. Tanaka et al.
(300 MHz, CDCl3) d 6.24 (2H, d,
J ¼ 2.4 Hz, Ar), 6.17 (1H, t, J ¼ 2.4 Hz,
Ar), 4.68 (2H, s, OH), 2.49 (2H, t,
J ¼ 7.5 Hz, ArCH2), 2.16–2.11 (4H, m,
CH2C ; CCH2), 1.60–1.28 (20H, m,
CH2), 0.89 (3H, t, J ¼ 6.6 Hz, CH3); 13C
NMR (75 MHz, CDCl3) d 156.7, 146.2,
108.2, 100.3, 96.6, 80.5, 80.4, 35.9, 31.5,
31.1, 29.3, 29.3, 29.1, 28.9, 28.7, 22.7,
18.9, 18.9, 14.2; HR-EI-MS: m/z 316.2386
[M]þ (calcd for C21H32O2, 316.2402).
References
[1] A. Kozubek and J.H.P. Tyman, Chem.
Rev. 99, 1 (1999).
[2] R.T. Scannell, J.R. Barr, V.S. Murty,
K.S. Reddy, and S.M. Hecht, J. Am.
Chem. Soc. 110, 3650 (1988).
[3] W. Lytollis, R.T. Scannell, H. An,
V.S. Murty, K.S. Reddy, J.R. Barr, and
S.M. Hecht, J. Am. Chem. Soc. 117,
12683 (1995).
[4] K. Matsumoto, M. Fujimoto, K. Ito,
H. Tanaka, and I. Hirono, J. Toxicol.
Sciences 15, 39 (1990).
[5] H. Hecker, R. Johannisson, E. Koch, and
C.P. Siegers, Toxicology 177, 167 (2002).
[6] M. Arisawa, K. Ohmura, A. Kobayashi,
and N. Morita, Chem. Pharm. Bull. 37,
2431 (1989).
[7] M. Himejima and I. Kubo, J. Agric. Food
Chem. 39, 418 (1991).
[8] I. Kubo, I. Kinst-Hori, and Y. Yokokawa,
J. Nat. Prod. 57, 545 (1994).
3.3 Cell lines and cytotoxicity test
The human fibroblast carcinoma KB cells
(purchased from ATCC) were grown in
Roswell Park Memorial Institute (RPMI)
1640 media (Invitrogen, Carlsbad, CA,
USA) containing 5% fetal bovine serum
(HyClone Laboratories, Logan, UT, USA),
and 0.1 mg/ml kanamycin (Invitrogen) at
378C in 5% CO2. All chemicals were
dissolved in DMSO (Sigma, St Louis, MO,
USA) and were stored at 2708C until use.
Cytotoxicity was determined by the MTS
assay (Promega, Madison, WI, USA)
according to the manufacturer’s instruc-
tion. Briefly, 2 £ 104 cells/well of KB cells
in a 96-well plate were treated with 0, 1, 3,
10, 30, and 100 mM compounds and
incubated for 48 h. For determining
cytotoxicity, MTS/phenazine methosulfate
solution was added into each well of the
96-well plate containing cells, and was
incubated at 378C in 5% CO2. After 2 h,
the absorbance was read at 490 nm
and their cytotoxicity was calculated by
comparing with 0.1% DMSO-treated cells,
the cytotoxicity of which being 100%.
[9] J.S. Lee, M. Hattori, and J. Kim,
Planta Med. 74, 532 (2008).
[10] K. Strøngaard and K. Nakanishi,
Angew. Chem. Int. Ed. 43, 1640 (2004).
[11] H. Itokawa, N. Totsuka, K. Nakahara,
K. Takeya, J.-P. Lepoittevin, and Y.
Asakawa, Chem. Pharm. Bull. 35, 3016
(1987).
[12] S. Nimgirawath, E. Ritchie, and W.C.
Taylor, Aust. J. Chem. 26, 183 (1973).
[13] C.J. Baylis, S.W.D. Odle, and J.H.P.
Tyman, J. Chem. Soc. Perkin Trans. 1 132
(1981).
[14] M.A. ElSohly, P.D. Adawadkar, D.A.
Benigni, E.S. Watson, and T.L. Little Jr,
J. Med. Chem. 29, 606 (1986).
[15] A. Fu¨rstner and G. Seidel, J. Org. Chem.
62, 2332 (1997).
[16] L.Q. Wu, C.G. Yang, L.M. Yang, and
L.J. Yang, J. Chem. Res. 183 (2009).
[17] N. Tsuge, M. Mizokami, S. Imai, A.
Shimazu, and H. Seto, J. Antibiotics 45,
886 (1992).
[18] G.N. Varseev and M.E. Maier, Angew.
Chem. Int. Ed. 45, 4767 (2006).
[19] V. Percec, M.R. Lmam, M. Peterca,
D.A. Wilson, and P.A. Heiney, J. Am.
Chem. Soc. 131, 1294 (2009).
Acknowledgements
This work was supported by a Grant-in-Aid for
Young Scientists (B) from the Ministry of
Education, Culture, Sports, Science and Tech-
nology of Japan (to T.U.), and by the KIST
Institutional Program, Republic of Korea
(to J.H. and S.K.).
[20] R.S. Narayan and B. Borhan, J. Org.
Chem. 71, 1416 (2006).
[21] M. Buck and J.M. Chong, Tetrahed. Lett.
42, 5825 (2001).
[22] A.L. Wilds and W.B. McCormack, J. Am.
Chem. Soc. 70, 4127 (1948).