A facile synthesis of naturally occurring binaphthoquinones: Efficient oxidative dimerization of 4-alkoxy-1-naphthols using silver(II) oxide-40% nitric acid

Article abstract of DOI:10.1016/S0040-4020(01)01130-9

Oxidation of 4-alkoxy-1-naphthols with AgO-40% HNO₃ occurred along with a dimerization to give the corresponding bi-1,4-naphthoquinones. The oxidative dimerization required one hydroxyl group and took place at its ortho position. This reaction was applicable to syntheses of naturally occurring binaphthoquinones, bivitamin K₃ and 3,3′-bijuglone.

Full text of DOI:10.1016/S0040-4020(01)01130-9

TETRAHEDRON
Pergamon
Tetrahedron 58 62002) 99±104
A facile synthesis of naturally occurring binaphthoquinones:
ef®cient oxidative dimerization of 4-alkoxy-1-naphthols using
silverꢀII) oxide±40% nitric acid
a,p
Yasuhiro Tanoue, Kazunori Sakata, Mamoru Hashimoto, Shin-ich Morishita,
b
b
c
b
Moritsugu Hamada, Norihisa Kai and Takeshi Nagai
a
a
a
Department of Food Science and Technology, National Fisheries University, Nagatahonmachi, Shimonoseki, Yamaguchi 759-6595, Japan
b
Department of Applied Chemistry, Faculty of Engineering, Kyushu Institute of Technology, Tobata-ku, Kitakyushu 804-8550, Japan
c
Department of Marine Engineering, National Fisheries University, Nagatahonmachi, Shimonoseki, Yamaguchi 759-6595, Japan
Received 31 August 2001; accepted 7 November 2001
3
AbstractÐOxidation of 4-alkoxy-1-naphthols with AgO±40% HNO occurred along with a dimerization to give the corresponding bi-1,4-
naphthoquinones. The oxidative dimerization required one hydroxyl group and took place at its ortho position. This reaction was applicable
0
to syntheses of naturally occurring binaphthoquinones, bivitamin K and 3,3 -bijuglone. q 2002 Elsevier Science Ltd. All rights reserved.
3
1. Introduction
naphthoquinone in high yield in one step. The present
paper describes oxidative dimerization of 4-alkoxy-1-
Naturally occurring binaphthoquinones, such as bivitamin
3,3 -biplumbagin,
naphthols using AgO±40% HNO
0
3
and its application to
and 3,3 -bijuglone.
1
a
1b
0
biramentaceone, mamegakinone, dianellinone, 3,3 -bi-
1c
0
1d
K ,
3
bilawsone,
3,3 -bijuglone,
syntheses of bivitamin K
3
1
e
1f
1g
0
1
h
1i
diomelquinone A, and xanthomegnin, contain a bi-1,4-
naphthoquinone moiety which is symmetrical 1,4-naphtho-
quinone. Usually, a synthesis of the bi-1,4-naphthoquinone
skeleton requires two steps. For example, biramentaceone
was prepared by oxidative coupling of 4-methoxy-1-
2
. Results and discussion
Oxidation of 4-methoxy-1-naphthol 61) with various
oxidants were carried out and the results are summarized
in Table 1. Treatment of 1 with CAN 6entry 1) or
NH ) S O ±AgNO 6entry 4) gave 1,4-naphthoquinone
4 2 2 8 3
2) as a main product. Interestingly, oxidation of 1 with
AgO±40% HNO in acetone at room temperature occurred
3
along with a dimerization to give selectively 2,2 -bi-1,4-
naphthoquinone 63) in 89% yield 6entry 2a). When chloro-
form 6entry 2c) or acetonitrile 62d) was the reaction solvent,
the binaphthoquinone was also obtained in good yield.
2
naphthol compounds using lead dioxide, or silver6I)
oxide6Ag O), followed by treatment with ꢀ5% HNO .
3
2
3
6
6
Mamegakinone dimethyl ether was prepared by conversion
of bromonaphthoquinone into a stannane derivative,
followed by Stille-type coupling reaction with the bromo-
naphthoquinone in the presence of bis6triphenylphosphine)
0
4
palladium6II) chloride.
On the other hand, the oxidation of 1,4-dimethoxynaph-
thalene and p-dimethoxybenzene derivatives to the corre-
sponding naphthoquinones and benzoquinones, respectively,
has been accomplished using such oxidants as cerium6IV)
In attempting to examine the oxidative dimerization using
AgO±40% HNO , reaction of various naphthols and their
3
5
derivatives with it were carried out and the results are
summarized in Table 2. The oxidative dimerization required
one hydroxyl group 6entries 3, 4, ꢀ and 7) and proceeded
with a methoxyl group 6entry ꢀ) or a methoxy methoxyl
group 6entry 7) in para position of the hydroxyl group,
whereas no dimerization occurred in cases of 1-naphthol
ammonium nitrate 6Ce6NH ) 6NO ) , CAN is used as the
4
2
3 ꢀ
ꢀ
abbreviation hereafter), silver6II) oxide6AgO)±HNO , and
6NH ) S O ±AgNO . In the course of our synthetic study
4 2 2 8 3
of naphthoquinone derivatives, we have found that oxida-
3
7
tion of 4-methoxy-1-naphthol with AgO±40% HNO occurs
3
0
along with a dimerization to give selectively 2,2 -bi-1,4-
6
entry 1), 1,4-dihydroxynaphthalene 6entry 2) and 1,4-
dimethoxynaphthalene 6entry 8). On the basis of these
results, we supposed the following reaction mechanism:
electron-rich aromatic substrates having a hydroxyl group
Keywords: binaphthoquinones; oxidative dimerization; alkoxynaphthols;
silver6II) oxide.
Corresponding author. Tel: 181-832-8ꢀ-5111; fax: 181-832-8ꢀ-7434;
e-mail: tanoue@®sh-u.ac.jp
p
were oxidized by Ag6II)±HNO system to generate an
3
0040±4020/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020601)01130-9

100
Y. Tanoue et al. / Tetrahedron 58 ꢀ2002) 99±104
Table 1. Oxidation of 4-methoxy-1-naphthol 61) with various oxidants
a
Entry
1
Oxidant
Reaction conditions
Temperature
Yield 6%)
Solvent
Time 6min)
2
3
Ce6NH
4
)
2
6NO
3
)
ꢀ
CH
CH
CH
3
3
3
CN±H
COCH
COCH
2
O
Rt
Rt
30
35
71
0
0
0
0
22
30
7
ꢀ9
1ꢀ
2
7
2a
2b
2c
2d
2e
2f
3
4
5
ꢀ
AgO±40% HNO
AgO±40% HNO
AgO±40% HNO
AgO±40% HNO
AgO±40% HNO
3
3
3
3
3
3
3
89
39
89
89
47
4
3
0±58C then rt
30 then 30
35
35
CHCl
CH CN
3
Rt
Rt
Rt
Rt
Rt
Rt
Rt
Rt
3
THF
dioxane
35
35
40
23 h
240
35
AgO±40% HNO
b
TI6NO
6NH
ꢀ5% HNO
Ag O±ꢀ5% HNO
3
)
3
´3H
2
O
CH
CH
±
3
OH
40
18
4
)
2
S
2
O
8
±AgNO
3
3
CN±H
2
O
3
2
3
CH COCH
3
3
0
4ꢀ
a
Isolated yield.
Ref. 8.
b
9
,10
aromatic radical cation
radical coupling gave binaphthoquinones.
and the subsequent radical±
Since the dimerization using AgO±40% HNO took place
3
1
1
at an ortho position of a hydroxyl group, we examined
whether the reaction occurs in compounds having a sub-
stituent group at the ortho position. Although the reaction
of 2-formyl- and 2-hydroxymethyl-4-methoxy-1-naphthols
resulted in destruction of the starting materials, interest-
ingly, the oxidation of 4-methoxy-2-methyl-1-naphthol
We next applied the oxidative dimerization to syntheses of
naturally occurring binaphthoquinones. The starting
material, 4-methoxy-3-methyl-1-naphthol 68) was prepared
from vitamin K 64) in four steps according to the literature
3
procedures. Oxidation of 8 with AgO±40% HNO gave
bivitamin K 69) in 59% yield as shown in Scheme 1. The
1
2±14
18
0
610)
gave the dimer, 2,2 -6ethylene)bi-1,4-naphtho-
3
1
5
quinone 611) in 98% yield 6Scheme 2). In order to compare
our procedure with Laatsch's it, oxidative coupling of 10
using Laatsch's procedure was attempted to give 11 in ꢀꢀ%
yield via the spiro compound 12 as shown in Scheme 3. The
X-ray stereostructure of 12, shown in Fig. 1, indicates that
12 has a spiro ring system.
3
compound 9 had been isolated before from the fern
1
ꢀ
Asplenium laciniatum by Gupta and co-workers. The
binaphthoquinone 9 was also synthesized in 58% yield
from 8 by the oxidative coupling of two steps using
3
,17
Laatsch's procedure.
Table 2. Oxidation of naphthols and their derivatives with AgO±40% HNO
3
a
Entry
1
Substrate
Yield 6%)
R
1
R
2
2
3
OH
OH
OH
OH
OH
OH
OH
OMe
OMe
OMe
H
18
0
0
20
2
0
2
3
4
5
ꢀ
7
8
9
1
OH
78
Cl
NH
2
7
2
´HCl
OCOCH
OMe
ꢀ
3
7
0
0
9
89
83
0
2
OCH OCH
OMe
3
b
Quant
53
520
OCOCH
CHO
3
0
0
a
Isolated yield.
Ref. ꢀ.
b

Y. Tanoue et al. / Tetrahedron 58 ꢀ2002) 99±104
101
Scheme 1.
Scheme 2.
Scheme 3.
Figure 1. X-Ray determined structure of 12.

102
Y. Tanoue et al. / Tetrahedron 58 ꢀ2002) 99±104
Scheme 4.
0
root bark of Juglans regia, as a second target compound.
According to the established procedure, the starting
material 13 was prepared in four steps from 1,5-dihydroxy-
We chose 3,3 -bijuglone which had been isolated from the
yield). Recrystallization of the monoester from hexane±
ethyl acetate 63:1) gave an analytical sample as light mud
yellow solid, mp 12ꢀ±1278C; IR 6KBr) 3420 6OH), 1737
1
9
2
0
2
1 1
6CvO), 1583, 1230, 10ꢀ4 cm ; H NMR d 2.44 6s, 3H,
CH ), 5.ꢀ26broad, 1H, OH), ꢀ.45 6d, Jˆ8.2Hz, 1H, ArH),
naphthalene. Oxidation of 13 with AgO±40% HNO gave
3
3
0
the dimer, 3,3 -bijuglone dimethyl ether 614) in 71% yield
ꢀ.91 6d, Jˆ8.2Hz, 1H, ArH), 7.43 6m, 1H, ArH), 7.49 6m,
1H, ArH), 7.726d, Jˆ8.2Hz, 1H, ArH), 8.0ꢀ 6d, Jˆ8.2Hz,
2
0
along with 5-methoxy-1,4-naphthoquinone in 3% yield.
At this point we encountered dif®culties in demethylation
of 14. Attempts employing BBr , Me SiI and AlCl3±
1
1H, ArH); C NMR d 20.97 6CH ), 107.ꢀ8, 117.84, 120.74,
3
3
2
1
21
122.31, 124.98, 125.1ꢀ, 125.49, 12ꢀ.83, 127.30, 139.ꢀ1,
149.85, 170.82; MS m/z 6rel. intensity, %) 202 6M , 1ꢀ),
3
3
2
2
1
Et2S resulted in destruction of 14 to give complex
products. Fortunately 3,3 -bijuglone 615) was obtained in
0
4% yield using 10 molar equiv. of AlCl3 in dichloro-
1ꢀ0 6100), 154 612), 131 615), ꢀ9 622); HRMS calcd for
C H O M 202.0ꢀ30, found 202.0589.
2
3
ꢀ
methane at room temperature for 22 h as shown in Scheme 4.
12
10
3
3.1.2. 4-Methoxymethoxy-1-naphthol. To a stirred and
In summary, we found that oxidation of 4-alkoxy-1-
naphthols with AgO±40% HNO occurs along with a dimer-
cooled 608C) solution of 1,4-dihydroxynaphthalene
6500 mg, 3.12mmol) in DMF 610 ml) was added sodium
hydride 6125 mg, ꢀ8% in paraf®n, 3.12 mmol) under a nitro-
gen atmosphere. After 10 min, chloromethyl methyl ether
6251 mg, 3.12 mmol) was added and stirring was continued
overnight. The reaction mixture was poured into water and
extracted with chloroform. The extracts were washed with
brine, dried over Na SO and evaporated. The residue was
3
ization. The oxidative dimerization required one hydroxyl
group and took place at its ortho position. The dimerization
was applicable to synthese of naturally occurring binaphtho-
0
24
quinones to give bivitamin K and 3,3 -bijuglone.
3
2
4
puri®ed by silica-gel chromatography to give 4-methoxy-
methoxy-1-naphthol 61ꢀ1 mg, 25 % yield) as oil; IR 6neat)
3
3. Experimental
2
1 1
380 6OH), 1595, 12ꢀ9, 1148, 1059 cm ; H NMR d 3.55
3
.1. General
6
ꢀ
s, 3H, OCH ), 5.31 6s, 2H, CH ), 5.39 6broad, 1H, OH),
3
2
1
13
H 6500 MHz) and C NMR 6125 MHz) spectra were taken
.ꢀ7 6d, Jˆ8.1 Hz, 1H, ArH), ꢀ.91 6d, Jˆ8.1 Hz, 1H, ArH),
7
.50 6m, 2H, ArH), 8.12 6m, 1H, ArH), 8.20 6m, 1H, ArH);
C NMR d 5ꢀ.14 6CH ), 95.4ꢀ 6CH ), 107.95, 108.ꢀ1,
on a JEOL JNM-A500 spectrometer in CDCl solutions
3
using Me Si and CDCl as an internal standard. EI mass
4
1
3
3
2
3
1
1
21.ꢀ0, 121.88, 125.21, 125.70, 125.9ꢀ, 12ꢀ.91, 14ꢀ.23,
47.02; MS m/z 6rel. intensity, %) 204 6M , 100), 174
spectra were performed with a JEOL JMS-SX 102A mass
spectrometer. Infrared spectra were recorded on a Shimadzu
IR 470 spectrometer. Melting points were observed with a
Yanaco MS-S3 micro melting point apparatus 6hot-plate
type). Elemental analyses were determined with a Yanaco
CHN Corder MT-3. X-Ray crystallography was measured
on a Rigaku automated four-circle diffractometer AFC7R
1
650), 159 688), 131 625), 115 61ꢀ), 103 620), 77 625);
HRMS calcd for C H O M 204.078ꢀ, found 204.0781.
12 12
3
3.2. General procedure for the oxidative dimerization
with graphite monochromatized Mo Ka radiation
Ê
Reaction of 4-methoxy-1-naphthol 61) is described as a typi-
cal example. To a mixture of 1 6100 mg, 0.574 mmol) and
AgO 6711 mg, 5.74 mmol) in acetone 610 ml) was added
40% HNO3 63 ml) over 5 min. After stirring at room
temperature for 30 min, the reaction mixture was diluted
with water and extracted with chloroform. The extracts
were washed with brine, dried over Na SO and evaporated.
6
lˆ0.710ꢀ9 A), the v ±2u scan technique being employed.
For preparative column chromatography, Wakogel C-200
silica gel was employed. Naphthols and their derivatives
except 4-acetoxy-1-naphthol, 4-methoxy-1-naphthol and
4
-acetoxy1-1-methoxynaphthalene in Table 2were
purchased from Tokyo Kasei Kogyo. 4-Acetoxy-1-
methoxynaphthalene was prepared by treatment of 4-
methoxy-1-naphthol with acetic anhydride in pyridine.
2
4
The crude product was puri®ed by silica-gel chromato-
0
graphy to give 2,2 -bi-1,4-naphthoquinone 63) 681 mg,
89% yield).
3
2
.1.1. 4-Acetoxy-1-naphthol. Acetic anhydride 6204 mg,
.0 mmol) was added to a solution of 1,4-dihydroxy-
0
3.2.1. 2,2 -Bi-1,4-naphthoquinone ꢀ3). Light mud yellow
2
5
naphthalene 6320 mg, 2.0 mmol) in pyridine 64 ml) and stir-
red at room temperature for 3 h. After concentration under
reduced pressure, the crude product was chromatographed
on silica-gel to give 4-acetoxy-1-naphthol 62ꢀ2 mg, ꢀ5%
yield) along with 1,4-diacetoxynaphthalene 684 mg, 17%
solid; mp 2ꢀ4±2ꢀ78C 6lit. 2ꢀ0±2ꢀ58C); IR 6KBr) 1ꢀꢀ3
1 1
2
6CvO), 1589, 1337, 1304, 1254, 1227, 772 cm ;
H
NMR d 7.08 6s, 2H, ArH), 7.58±8.30 6m, 8H, ArH); MS
1
m/z 6rel. intensity, %) 314 6M , 100), 297 6ꢀ8), 258 615),
230 615), 202 637).

Y. Tanoue et al. / Tetrahedron 58 ꢀ2002) 99±104
103
3.2.2. Bivitamin K ꢀ9). Mud yellow prisms 6from aceto-
nitrile); mp 249±2518C 6lit. 243±24ꢀ8C); IR 6KBr) 1ꢀꢀ1
After evaporation of the solvent, chromatographic puri®ca-
tion 6chloroform) gave the dimer 11 6ꢀ0 mg, ꢀꢀ% yield). In
order to determine the structure of 12, the other crude
product of 12 was puri®ed by silica-gel chromatography
eluting with chloroform, followed by recrystallization
from hexane±ethyl acetate 610:1). 12: Yellow prisms; mp
131±1328C; IR 6KBr) 1ꢀ90 6CvO), 159ꢀ, 1385, 12ꢀ7,
3
1
ꢀ
2
1 1
6
CvO), 1593, 1284 cm ; H NMR d 2.07 6s, ꢀH, CH ),
3
7
.7ꢀ 6m, 4H, ArH), 8.09 6m, 2H, ArH), 8.17 6m, 2H, ArH);
C NMR d 14.3ꢀ 6CH ), 12ꢀ.ꢀ3, 12ꢀ.ꢀꢀ, 131.93, 132.10,
33.88, 133.94, 140.54, 145.77, 182.ꢀ2 6CvO), 184.43
1
3
3
1
1
6CvO); MS m/z 6rel. intensity, %) 3426M , 100), 327
672), 313 630), 300 640), 285 622), 271 613), 239 615), 228
614), 215 620), 152 620), 104 635), 7ꢀ 640). Anal. Calcd for
2
1 1
1101, 7ꢀ4 cm ; H NMR d 2.13 6m, 1H, H±C±H), 2.25
6m, 1H, H±C±H), 2.94 6m, 2H, CH ), 3.7ꢀ 6s, 3H, OCH -
2
3
0
ArH-5), 7.44 6m, 3H, ArH), 7.ꢀ5 6m, 1H, ArH), 7.73 6d,
0
C H O : C, 77.18; H, 4.12. Found: C, 77.08; H, 4.18.
2
4 ), 3.9ꢀ 6s, 3H, OCH -ꢀ), 5.35 6s, 1H, H-3 ), ꢀ.51 6s, 1H,
3
2
14
4
0
mud yellow solid 6from chloroform±ethyl acetate 610:1));
mp 248±2498C; IR 6KBr) 1ꢀꢀ26C vO), 1ꢀ1ꢀ, 1592,
3
.2.3. 2,2 -ꢀEthylene)bi-1,4-naphthoquinone ꢀ11). Light
Jˆ7.3 Hz, 1H, ArH), 8.026dd, Jˆ7.ꢀ and 0.9 Hz, 1H,
1
3
ArH), 8.17 6m, 2H, ArH); C NMR d 22.53 6CH ), 31.33
2
6CH ), 55.15 6OCH ), 55.70 6OCH ), 78.9ꢀ, 100.97, 104.91,
2
3
3
2
1
303 cm ; H NMR d 2.89 6s, 4H, CH ), ꢀ.83 6s, 2H,
1
1
quinone H), 7.75 6m, 4H, ArH), 8.07 6m, 2H, ArH), 8.10
6
113.32, 121.5ꢀ 62C), 122.ꢀ5, 125.15, 125.42, 125.8ꢀ,
12ꢀ.11, 127.37, 128.ꢀ7, 128.90, 134.52, 134.57, 141.98,
149.0ꢀ, 150.81, 197.81 6CvO); MS m/z 6rel. intensity, %)
2
1
3
m, 2H, ArH); C NMR d 28.43 6CH ), 12ꢀ.18, 12ꢀ.70,
2
1
1
32.0ꢀ, 132.1ꢀ, 133.81, 133.87, 135.43, 149.81, 184.83
CvO), 184.926C vO); MS m/z 6rel. intensity, %), 342
3726M , 42), 370 6100), 355 652), 187 6ꢀ2), 18ꢀ 65ꢀ). Anal.
Calcd for C H O : C, 77.40; H, 5.41. Found: C, 77.11; H,
5.40.
6
2
4
20
4
1
M , 100), 325 620), 313 610), 297 61ꢀ), 115 639), 7ꢀ
6
6
C, 7ꢀ.7ꢀ; H, 4.13.
33). Anal. Calcd for C H O : C, 77.18; H, 4.12. Found:
2
2
14
4
Single crystals of 12 were grown from hexane±ethyl acetate
Ê
6
3:1) and were monoclinic space group P2 /n, aˆꢀ.5 61) A,
1
0
3
3
.2.4. 3,3 -Bijuglone dimethyl ether ꢀ14). Yellow plates
bˆ27.1 62) AÊ , cˆ10.ꢀ 61) AÊ , bˆ93 61)8, Vˆ1877 649) AÊ ,
1
9
6
from acetonitrile); mp ,25ꢀ8C 6dec.) 6lit. mp 2508C);
IR 6KBr) 1ꢀ58 6CvO), 1585, 131ꢀ, 1279, 1215,
Zˆ4, Rintˆ0.0ꢀ3, Rˆ0.114, Rwˆ0.105, R1ˆ0.047.
2
022 cm ; H NMR d 3.99 6s, ꢀH, OCH ), ꢀ.95 6s, 2H,
1
1
1
quinone H), 7.33 6m, 2H, ArH), 7.73 6m, 4H, ArH);
Crystallographic data for 12 has been deposited with the
Cambridge Crystallographic Data Center as the deposition
number CCDC 1ꢀ4999. Copies of the data can be obtained
free of charge on application to The Director, CCDC, 12
Union Road, Cambridge, CB21EZ, UK 6Fax: 144-1223-
33ꢀ-033; e-mail: deposit@ccdc.cam.ac.uk or www: http//
www.ccdc.cam.ac.uk).
3
1
3
C
NMR d 5ꢀ.45 6OCH ), 118.14, 119.0ꢀ, 119.79, 134.19,
3
1
6
34.81, 135.27, 14ꢀ.78, 1ꢀ0.05, 182.10 6CvO), 184.43
CvO); MS m/z 6rel. intensity, %) 374 6M , 100), 357
1
6
91), 23ꢀ 623), 189 61ꢀ), 7ꢀ 652). Anal. Calcd for
C H O : C, 70.59; H, 3.77. Found: C, 70.38; H, 3.80.
2
2
14
ꢀ
3
0
.2.5. Demethylation of 14. To a solution of 14 687 mg,
.231 mmol) in dichloromethane 630 ml) was added AlCl3
Acknowledgements
6
2
308 mg, 2.31 mmol). After stirring at room temperature for
2 h, the reaction mixture was decomposed with 5%
We are grateful to Ms F. Eguchi and Messrs D. Umemoto
and M. Mitsumori for their technical assistance. We are also
thankful to the Center for Instrumental Analysis, Kyushu
Institute of Technology for elemental analyses, mass
spectra, NMR spectra and X-ray diffraction.
aqueous oxalic acid 620 ml), extracted with chloroform,
washed with brine, dried over Na SO , and concentrated.
The residue was puri®ed by silica-gel chromatography to
2
4
0
give 3,3 -bijuglone 615) 651 mg, ꢀ4% yield). Orange solid;
mp 2ꢀ5±2ꢀ78C 6dec.) 6lit. 2708C); IR 6KBr) 1ꢀꢀ3 6CvO),
3
2
ꢀ27 6CvO), 1454, 1293 cm ; H NMR d 7.04 6s, 2H,
1
1
1
quinone H), 7.34 6m, 2H, ArH), 7.70 6s, 4H, ArH), 11.7ꢀ
1
s, 2H, OH); MS m/z 6rel. intensity, %) 34ꢀ 6M , 100), 329
6
References
6
6
22), 289 625), 2ꢀ2 623), 234 618), 205 619), 120 623), 92
40); HRMS calcd for C H O M 34ꢀ.0478, found
20 10 ꢀ
1. 6a) Thomson, R. H. Naturally Occurring Quinones III;
Chapman & Hall: New York, 1987; p 128. 6b) Thomson,
R. H. Naturally Occurring Quinones III; Chapman & Hall:
New York, 1987; p 138. 6c) Thomson, R. H. Naturally
Occurring Quinones III; Chapman & Hall: New York, 1987;
p 15ꢀ. 6d) Thomson, R. H. Naturally Occurring Quinones III;
Chapman & Hall: New York, 1987; p 1ꢀ1. 6e) Thomson, R. H.
Naturally Occurring Quinones III; Chapman & Hall: New
York, 1987; p 1ꢀ5. 6f) Thomson, R. H. Naturally Occurring
Quinones III; Chapman & Hall: New York, 1987; p 1ꢀꢀ.
6g) Thomson, R. H. Naturally Occurring Quinones III;
Chapman & Hall: New York, 1987; p 18ꢀ. 6h) Thomson,
R. H. Naturally Occurring Quinones III; Chapman & Hall:
New York, 1987; p 213. 6i) Thomson, R. H. Naturally
Occurring Quinones III; Chapman & Hall: New York, 1987;
p 313.
3
4ꢀ.04ꢀ2.
3
method
.3. Oxidative dimerization of two steps by Laatsch's
;17
3
3
0
.3.1. Synthesis of 11 from 10. To a solution of 10 6100 mg,
.531 mmol) in chloroform 610 ml) was added triethyl-
amine 60.02ml) and Ag O 6ꢀ1ꢀ mg, 2.ꢀꢀ mmol). The
2
mixture was stirred at room temperature for 24 h and ®ltered
off. The ®ltrate was evaporated in vacuo to give the crude
product 12, which was used for the following reaction with-
out puri®cation. To the crude 12 was added ꢀ5% HNO3
6
3
4 ml). The mixture was stirred at room temperature for
min and diluted with water and extracted with chloroform.
The extracts were washed with brine and dried over Na SO .
2
4

104
Y. Tanoue et al. / Tetrahedron 58 ꢀ2002) 99±104
2
. Maiti, B. C.; Musgrave, O. C.; Skoyles, D. J. Chem. Soc., 14. Toyoda, H.; Nakagawa, K.; Fukawa, H. Japan Patent 14ꢀ28,
Chem. Commun. 1976, 244±245.
19ꢀ7; Chem. Abstr., 1968, 68, 49351h.
3
. Laatsch, H. Liebigs Ann. Chem. 1980, 1321±1347.
. Bringmann, G.; Gotz, R.; Keller, P. A.; Walter, R.; Boyd,
M. R.; Lang, F.; Garcia, A.; Walsh, J. J.; Tellitu, I.; Bhaskar,
K. V.; Kelly, T. S. J. Org. Chem. 1998, 63, 1090±1097.
. Jacob, III, P.; Callery, P. S.; Shulgin, A. T.; Castagnoli, Jr., N.
J. Org. Chem. 1976, 41, 3ꢀ27±3ꢀ29.
15. For the ®rst synthesis, see: Gupta, R. B.; Khanna, R. N.;
Manchanda, V. P. Indian J. Chem. 1979, 18B, 217±218.
1ꢀ. Gupta, R. B.; Khanna, R. N.; Sharma, N. N. Indian J. Chem.
1977, 15B, 394±395.
4
5
ꢀ
7
17. Laatsch, H. Tetrahedron Lett. 1976, 3287±3290.
18. Laatsch, H. Liebigs Ann. Chem. 1980, 140±157.
19. Pardhasaradhi, M.; Babu, M. H. Phytochemistry 1978, 17,
2042±2043.
. Snyder, C. D.; Rapoport, H. J. Am. Chem. Soc. 1972, 94, 2 2 7±
231.
. Tanoue, Y.; Sakata, K.; Hashimoto, M.; Morishita, S.;
Hamada, M.; Kai, N.; Nagai, T. Bull. Chem. Soc. Jpn 1994,
20. Hannan, R. L.; Barker, R. B.; Rapoport, H. J. Org. Chem.
1979, 44, 2153±2158.
6
7, 2593±2595.
21. For a review on cleavage of ethers, see: Bhatt, M. V.;
Kulkarni, S. U. Synthesis 1983, 249±282.
8
. For oxidation of hydroquinone with thallium6III) nitrate, see:
McKillop, A.; Perry, D. H.; Edwards, M.; Antus, S.; Farkas,
L.; Nogradi, M.; Taylor, E. C. J. Org. Chem. 1976, 41, 282±
22. Nomura, K.; Okazaki, K.; Hori, K.; Yoshii, E. J. Am. Chem.
Soc. 1987, 109, 3402±3408.
2
87.
23. 6a) Li, T.-tee.; Ellison, R. H. J. Am. Chem. Soc. 1978, 100,
ꢀ2ꢀ3±ꢀ2ꢀ5. 6b) Yoshida, M.; Mori, K. Eur. J. Org. Chem.
2000, 1313±1317.
9
. McKillop, A.; Turrell, A. G.; Young, D. W.; Taylor, E. C.
J. Am. Chem. Soc. 1980, 102, ꢀ504±ꢀ512.
1
1
1
1
0. Tanoue, Y.; Terada, A. Bull. Chem. Soc. Jpn 1988, 61, 2039±
045.
1. Okamoto, I.; Doi, H.; Kotani, E.; Takeya, T. Tetrahedron Lett.
001, 42, 2987±2989.
2. Synder, C. D.; Rapoport, H. J. Am. Chem. Soc. 1974, 96,
04ꢀ±8054.
3. Abe, Y.; Ishikawa, H. Japan Patent ꢀ172, 1951; Chem. Abstr.,
951, 47, 10007b.
24. During preparation of this manuscript, Takeya et al. reported
0
0
2
that 3,3 -biplunbagin dimethyl ether, that is 2,2 -dimethyl-
0
3,3 -bijuglone dimethyl ether, was prepared by an aryl±aryl
2
coupling of a naphthol using SnCl
with ꢀ5% HNO 6see Ref. 11).
25. Ullmann, F. Helv. Chim. Acta 1926, 9, 442±443.
4
, followed by treatment
3
8
1