Efficient synthesis of a new L-shaped dimer of naphthalene, and its analogs

Article abstract of DOI:10.1271/bbb.80306

Efficient syntheses of 14H-dinaphtho[1,8-bc:1′,8′-fg]oxocin-14- one (2), 14H-dinaphtho[1,8-bc:1′,2′-f]oxepin-14-one (3), and 2,20(2H,2′H)-spirobi[naphtho[1,8-bc]furan] (9) are described. The putative structure of 2 has been reported previously, but the synthetic route was not reproducible. 7H-Dibenzo[c,h]xanthen-7-one (4), a known compound, was obtained by a different method. Possible reaction mechanism are proposed.

Full text of DOI:10.1271/bbb.80306

Biosci. Biotechnol. Biochem., 72 (10), 2632–2639, 2008
Efficient Synthesis of a New L-Shaped Dimer
of Naphthalene, and Its Analogs
Ken YOSHIOKA,1 Izumi TAKAISHI,1 Kazunari SHIOZAWA,2
y
1
Yukiharu FUKUSHI,1; and Satoshi TAHARA
1Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University,
Sapporo, Hokkaido 060-8589, Japan
2Mitsui Chemical Analysis and Consulting Service, Inc.,
580-32 Nagaura, Sodegaura, Chiba 299-0265, Japan
Received May 2, 2008; Accepted June 11, 2008; Online Publication, October 7, 2008
[doi:10.1271/bbb.80306]
Efficient syntheses of 14H-dinaphtho[1,8-bc:10,80-
fg]oxocin-14-one (2), 14H-dinaphtho[1,8-bc:10,20-f]oxe-
pin-14-one (3), and 2,20(2H,20H)-spirobi[naphtho[1,8-
bc]furan] (9) are described. The putative structure of
2 has been reported previously, but the synthetic route
O
H O
O
was not reproducible. 7H-Dibenzo[c,h]xanthen-7-one
(4), a known compound, was obtained by a different
method. Possible reaction mechanism are proposed.
O
Key words: L-shaped dimer; chiral derivatizing re-
agents; anisotropy effect; Friedel-Crafts
cyclization reaction
Fig. 1. A Target Molecule as a New Chiral Reagent.
O
In recent years, many reagents have been developed
for chiral recognition of organic compounds by NMR,1)
and our group has reported several axially chiral
reagents for this purpose.2–4) In an attempt to develop
more useful reagents, we designed a new reagent that
has an L-shaped dimer of naphthalene5) as a skeleton
and has strong anisotropy effects due to naphthalene
moieties (Fig. 1). 14H-Dinaphtho[1,8-bc:10,80-fg]oxo-
cin-14-one (2) is a skeleton of this designed reagent
that was synthesized by Kubo and Sato,6) but the
reported method was not reproducible. In addition, to
our knowledge, an efficient method for the synthesis
of L-shaped compounds such as 2 has not yet been
developed. This may be due to the fact that these
L-shaped dimers have no known applications; never-
theless, they have unique and attractive structures. Here
we report the efficient synthesis of L-shaped dimer 2
and its analogs, which were found in the reaction
process for 2.
PPA
O
O
CO2H
100°C, 30 min
Low yield
1
2
Scheme 1.
carboxylic acid 1 in polyphosphoric acid (PPA)
(Scheme 1). We repeated the reaction under the original
conditions, but did not obtain 2, instead obtaining a
7-membered adduct (3) in 86% yield and a 6-membered
adduct (4) in 14% yield. When we used TFAA along
with a catalytic amount of trifluoromethansulfonic acid,
the reaction gave 3 exclusively (Scheme 2). These
results indicate that the formation of 3 proceeds under
kinetic control while the formation of 4 proceeds under
thermodynamic control. 7H-Dibenzo[c,h]xanthen-7-one
(4) is a known compound synthesized by the reaction
naphthol and hydroxynaphthoate.7) We did not obtain
dimer 4 by treatment of 3 in PPA at 100 ꢀC for 8 h. This
result indicates that dimer 4 is formed from an
Results and Discussion
According to the literature,6) the L-shaped compound
2 is synthesized by Friedel-Crafts ring closure of
y
To whom correspondence should be addressed. Fax: +81-11-706-4182; E-mail: y-fuku@abs.agr.hokudai.ac.jp

Efficient Synthesis of a New L-Shaped Dimer of Naphthalene
2633
2
1
O
14
O
O
3
a
O
7
1
+
b
3
4
14%
86%
3
100%
Scheme 2.
Reagents and conditions: (a) PPA, 100 ꢀC, 30 min; (b) (CF3CO)2O, CF3SO3H, CH2Cl2, 0 ꢀC, 1 min
a
a
O
PPA
O
O
H
CO2H
H
O
O
O
O
b
a
b
-H+
1
O
b + a
O
3
c
-H+
d
O
O
d
O
O
O
O
O
O
H
-H+
c
4
Scheme 3. Possible Mechanism for the Formation of 3 and 4.
intermediate in Friedel-Crafts cyclization reaction of 1.
A possible mechanism is shown in Scheme 3.
spiro compound 9 by the same method, but using
pyridine instead of NMP. The structure of 2 was
established on the basis of extensive 2D NMR analysis
Dimer 3 was a new compound, and hence we
determined its structure by extensive 2D NMR analysis
(Table 1). The 1H NMR spectrum showed two clear
doulets, which were attributable to H-12 and H-13. We
found the physicochemical data of 3 to be very similar to
those of 2 in the original study by Kudo and Sato6)
(Table 2). Their similarities were as follows: (i) The UV
spectral data of 3 were completely coincident with those
of 2 (reported). (ii) Methine carbon signals of 3 in
13C NMR were approximately coincident with those of
2 (reported). (iii) The values of their melting points are
similar. We estimated that compound 3 might in fact has
been 2 in the study.6)
Since we were unable to obtain 2 by the route shown in
Scheme 1, we developed a new, efficient synthetic route,
as shown in Scheme 4. Lithium intermediate 68) was
easily prepared from 1,8-dibromonaphthalene 5;9) treat-
ment of 6 with lactone 710) gave ketone 8 in quantitative
yield. An intramolecular Ullmann ether coupling reac-
tion11) of 8 in 1-methyl-2-pyrrolidone (NMP) gave dimer
2 exclusively. In addition, we selectively obtained a new
*
(Table 3); single-crystal X-ray analysis of 2 (Fig. 2)
confirmed the interpretation of the NMR data. We
determined the structure of 9 by extensive 2D NMR
analysis (Table 4). The 13C NMR spectrum included 11
signals containing acetal carbon (ꢀ122:4). This indicates
that 9 was asymmetrical spiroketal.
In addition, we briefly investigated substituent
effects in Friedel-Crafts ring closure (Scheme 5). Car-
boxylic acid 10 was prepared by Ullmann ether coupl-
ing of 7-methoxy-1-naphthol with isopropyl 8-iodo-1-
naphthoate,4) followed by hydrolysis. Carboxylic acid
11 was prepared by Ullmann ether coupling of 1-
naphthol with isopropyl 8-iodo-1-naphthoate, followed
by bromination12) and hydrolysis. Friedel-Crafts ring
*
Thecrystal information file on 2 was deposited in the Cambridge
Crystallographic Data Center as supplementary publication
no. CCDC-685567. Copies of the data can be obtained free
of charge by application to CCDC, 12 Union Road, Cambridge
CB2 1EZ, U.K. (Fax: +44-1223-336-033; E-mail: deposit@ccdc.
cam.ac.uk).

2634
K. YOSHIOKA et al.
Table 1. NMR Data for 3 in C5D5N
Position
ꢀC
ꢀHa(J ¼ Hz)
8.54 d (7.5, 1.0)
COSY
NOESY
HMBCb
1
130.4
126.1
134.8
136.0
126.2
127.0
119.2
153.5
153.1
126.8
123.5
127.5
128.8
128.2
137.1
125.2
125.3
130.0
193.2
133.2
125.5
2
2
3
—
2
7.57 dd (8.2, 7.5)
8.10 dd (8.2, 1.0)
1, 3
2
1, 3
2, 4
—
3
1, 4
2, 5
3, 6
—
3a
4
—
7.78 dd (8.1, 1.0)
—
5, 6
4, 6
4, 5
—
3, 5
4, 6
4, 5
—
5
7.53 dd (8.1, 7.5)
7.86 dd (7.5, 1.0)
6
4
6a
7a
7b
8
—
—
5
—
—
—
—
8, 13
9, 11, 12
10
—
8.88 dd (8.1, 0.8)
9
6, 9, 10
8, 10
9, 11
10, 12
—
9
7.70 ddd (8.1, 7.2, 0.8)
7.62 ddd (7.5, 7.2, 0.8)
8, 10
9, 11
10
11
8
10
11
11a
12
13
13a
14
14a
14b
7.91 dd (7.5, 0.8)
—
9, 12
8, 10, 13
11
—
13
7.74 d (8.5)
7.88 d (8.5)
13
12
12
—
—
12
—
—
—
—
—
—
—
—
1, 13
2
—
—
—
1, 4, 6
aFrom HMQC.
bNumbers show proton positions.
Table 2. Comparison of Physiochemical Data for 2 (previously reported), 3, and 2 (present report)
O
O
O
O
O
O
2 (previously reported)
3
2 (present report)
State
and m.p.
Pale yellow needles
210–212 ꢀC (benzene)
Pale yellow plates
226.2–226.8 ꢀC (benzene)
Colorless needles
297.5–298.0 ꢀC (benzene)
UV
(EtOH)
215 (4.89)
257 (4.42)
293 (3.87)
303 sh (3.82)
333 (3.81)
356 sh (3.76)
215 (4.91)
258 (4.44)
293 (3.86)
303 sh (3.82)
338 (3.80)
356 sh (3.76)
214 (4.69)
234 (4.07)
306 (3.59)
333 (3.48)
13C NMR
(CDCl3)
118.7
123.4
124.4
124.9
126.0
127.0
128.0
128.6
129.6
130.4
131.9
133.2
134.0
134.5
135.8
136.9
173.2
118.7 (CH)
123.3 (CH)
124.8 (CH)
124.9 (CH)
125.5 (C)
118.8
125.4
125.5
125.6
126.5
126.9
129.6
134.8
138.5
155.1
204.6
125.6 (C)
125.9 (CH)
126.4 (CH)
126.6 (C)
127.0 (CH)
127.9 (CH)
128.4 (CH)
129.5 (CH)
130.2 (CH)
133.1 (CH)
134.4 (CH)
135.7 (C)
136.8 (C)
153.0 (CH)
153.5 (CH)
193.6 (C=O)

Efficient Synthesis of a New L-Shaped Dimer of Naphthalene
2635
O
14
a
1
O
2
7
Br
Li
Br Br
3
6
5
c
2
O
Br
O
b
91%
d
O
OH
98%
74%
1
O
7
8
2
O
3
9
Scheme 4.
Reagents and conditions: (a) n-BuLi, hexane, ꢁ78 ꢀC, 30 min; (b) Et2O, 0 ꢀC ! r.t., 2 h;
(c) K2CO3, Cu2O, Py., refl. 1 h; (d) K2CO3, Cu2O, NMP, refl. 1 h
Table 3. NMR Data for 2 in C5D5N
ꢀHa(J ¼ Hz) COSY NOESY HMBCb
126.1 7.80 dd (7.4, 1.0)
Table 4. NMR Data for 9 in CDCl3
ꢀHa(J ¼ Hz) COSY NOESY HMBCb
Position
ꢀC
Position
ꢀC
ꢂ
ꢂ
ꢂ
1
2
3
2
122.4
136.5
126.8
—
—
—
—
—
—
4
—
—
—
4
3, 4
4, 5
2
127.1 7.51 dd (8.5, 7.4) 1, 3
—
1, 4
2a
2b
3
3
130.0 7.85 dd (8.5, 1.0)
135.2
126.2 7.71 dd (8.1, 1.0)
2
3, 5, 6, 8
3, 4, 5
3, 5
3a
4
—
—
5
—
5
2, 5
3, 4
119.8 7.26 d (7.4)
4
129.1 7.60 dd (8.2, 7.4) 3, 5
3, 5
4, 6
—
5
127.6 7.48 dd (8.1, 7.5) 4, 6
120.0 7.89 dd (7.5, 1.0)
4, 6
5
—
5
126.4 7.91 d (8.2)
131.1
117.4 7.50 d (8.5)
4
—
ꢂ
3, 5, 6
4, 5, 7
5, 6, 8
6
6
5
4
4, 5
5a
6
—
ꢂ
6a
14
14a
14b
155.5
204.0
139.1
125.7
—
—
—
—
—
—
—
—
—
—
—
—
5,
ꢂ, 8
1
7
129.8 7.54 dd (8.5, 7.4) ꢂ, 8
2
1, 3, 4, 6
8
8a
102.7 6.91 d (7.4)
157.0
7
—
7
—
6, 8
5, 7, 8
—
aFrom HMQC.
bNumbers show proton positions.
ꢂOverlapped.
aFrom HMQC.
bNumbers show proton positions.
ꢂOverlapped.
such as 1, Friedel-Crafts closure will occur at the 20
position, not at the 80 position, regardless of the
directing effect. 8-Membered compounds such as 2 are
known not to invert at over 200 ꢀC, but 7-membered
compounds such as 3 have been reported to invert
easily at room temperature.13) Hence, the resulting
7-membered compounds (3, 11, and 12) might have
been unsuitable as skeletons for our chiral reagents due
to their potential flappable structure.
In conclusion, we succeeded in developing efficient
syntheses for L-shaped naphthalene dimer 2, 7-mem-
bered compounds 3, 12, and 13, and spiro compound 9.
Further derivatization of 2 and 9 to form chiral
recognition reagents and/or chiral ligands for asymmet-
ric synthesis is under investigation.
Fig. 2. Molecular Structure of 14H-Dinaphtho[1,8-bc:10,80-fg]oxo-
cin-14-one (2).
closure of 10 afforded 12 selectively, although 10
contains an electron-donating group at the 70 position.
Similarly, ring closure of 11 gave 13 selectively, even
though 11 has an electron-withdrawing group at the
40 position. These results indicate that if there is a
hydrogen at the 20 position of any dinaphthyl ether
Experimental
General procedures. Et2O was dried by distillation
over Na/benzophenone under a nitrogen atmosphere.
Unless otherwise stated, solvent and reagents were used

2636
K. YOSHIOKA et al.
1
3
c
81%
Br
Br
O
O
O
e
c
d
a
O
O
CO2
CO2
CO2H
I
CO2
Br
99%
91%
55%
80%
13
16
14
11
b
47%
O
OMe
e
OMe
CO2H
c
O
O
O
CO2
78%
97%
MeO
12
15
10
Scheme 5.
Reagents and conditions: (a) 1-naphthol, K2CO3, Cu2O, Py. refl. 4 h; (b) 7-methoxy-1-napthol, K2CO3, Cu2O, Py. refl. 5 h;
(c) KOH, DMI, 100–130 ꢀC, 0.5–4 h; (d) NBS, CH2Cl2, r.t., 6 h; (e) (CF3CO)2O, CF3SO3H, CH2Cl2, 0 ꢀC, 1 min
without purification. NMR spectra were recorded at
500 MHz/125 MHz (1H/13C) in CDCl3, unless stated
otherwise.
30 min. After cooling, the mixture was neutralized with
sat. aq. K2CO3 (30 ml) and extracted with CHCl3. The
organic layer was washed with brine, dried over
MgSO4, and concentrated in vacuo. Purification of the
residue by column chromatography on SiO2 using
CHCl3 as eluent afforded 74 mg (86%) of 3 and 13 mg
of 4 (14%). Procedure 2: To a suspension of 1 (100 mg,
0.32 mmol) in CH2Cl2 (5 ml) was added trifluoroacetic
anhydride (67 ml, 0.48 mmol) at 0 ꢀC, and trifluorome-
thanesulfonic acid (3 ml, 0.03 mmol) was added to the
resulting yellow solution. After 1 min, the reaction
mixture was poured into 2 M aq. HCl and extracted with
CHCl3. The organic layer was washed with brine, dried
over MgSO4, and concentrated in vacuo. Purification of
the residue by column chromatography on SiO2 using
CHCl3 as eluent afforded 95 mg (100%) of 3 as a
yellow solid.
3: Pale yellow plates; m.p.: 218.0–219.0 ꢀC (EtOH),
226.2–226.8 ꢀC (benzene); IR ꢁmax (KBr) cmꢁ1: 2363,
1651, 1503, 1457, 1428, 1348, 1282, 1240, 1122, 1029,
879, 836, 820, 803, 767; UV ꢂmax (EtOH) nm (log "):
215 (4.89), 258 (4.44), 293 (3.86), 303 sh (3.82), 338
(3.80). 356 sh (3.76); NMR ꢀH (270 MHz, CDCl3): 7.48–
7.74 (8H, m), 7.86 (1H, d, J ¼ 8:1 Hz), 8.07 (1H, d, J ¼
7:3 Hz), 8.43 (1H. d, J ¼ 8:1 Hz), 8.74 (1H, d, J ¼
8:1 Hz); NMR ꢀC (63 MHz, CDCl3): 193.6, 153.5, 153.0,
136.8, 135.7, 134.4, 133.1, 130.2, 129.5, 128.4, 127.9,
127.0, 126.6, 126.4, 125.9, 125.6, 125.5, 124.9, 124.8,
123.3, 118.7; NMR ꢀH (500 MHz, C5D5N) and NMR ꢀC
(125 MHz, C5D5N): see Table 1; EIMS m=z (rel. int. %):
297 (Mþ þ 1, 30), 296 (Mþ, 100), 269 (20), 268 (95),
239 (42), 237 (15), 134 (23), 120 (16); HREIMS m=z
(Mþ): Calcd. for C21H12O2: 296.0838, Found: 296.0795.
4: Colorless needles; m.p.: 258.8–259.2 (EtOH), lit.
251–253 ꢀC;7) IR ꢁmax (KBr) cmꢁ1: 2363, 2341, 1700,
1653, 1559, 1541, 1460, 669; UV ꢂmax (EtOH) nm
14H-Dinaphtho[1,8-bc:10,80-fg]oxocin-14-one (2). To
a solution of 8 (0.20 g, 0.52 mmol) and potassium
carbonate (0.11 g, 0.79 mmol) in degassed NMP was
added Cu2O (7 mg, 0.05 mmol). The reaction mixture
was heated at reflux for 1 h, cooled to room temperature,
and concentrated in vacuo. The residue was dissolved in
a mixture of 2 M aq. HCl and EtOAc, and the water layer
was extracted with additional EtOAc. The combined
EtOAc layers were washed with brine, dried over
MgSO4, and concentrated in vacuo. Purification of the
residue by column chromatography on SiO2 using CHCl3
as eluent afforded 0.14 g (91%) of 2 as a colorless solid.
2: Colorless needles; m.p.: 292.5–293.5 ꢀC (acetone),
297.5–298.0 ꢀC (benzene); IR ꢁmax (KBr) cmꢁ1: 1662,
1458, 1331, 1224, 1128, 880, 845, 823, 779; UV ꢂmax
(EtOH) nm (log "): 214 (4.69), 234 (4.07), 306 (3.59),
333 (3.48); NMR ꢀH (500 MHz, CDCl3): 7.49–7.56 (2H,
m), 7.60 (1H, dd, J ¼ 7:1, 1.0 Hz), 7.68–7.71 (2H, m),
7.85 (1H, dd, J ¼ 8:2, 1.0 Hz); NMR ꢀC (125 MHz,
CDCl3): 204.6, 155.1, 138.5, 134.8, 129.6, 126.9, 126.5,
125.6, 125.5, 125.4, 118.8; NMR ꢀH (500 MHz, C5D5N):
see Table 2; NMR ꢀC (125 MHz, C5D5N): see Table 2.;
EIMS m=z (rel. int. %): 297 (Mþ þ 1, 22), 296 (Mþ,
100), 269 (14), 268 (60), 242 (37), 240 (20), 239 (64),
237 (20), 214 (14), 213 (11), 134 (20), 120 (25), 119
(17), 107 (11), 44 (15), 40 (16); HREIMS m=z (Mþ):
Calcd. for C21H12O2: 296.0838, Found: 296.0872.
14H-Dinaphtho[1,8-bc:10,20-f]oxepin-14-one (3) and
7H-dibenzo[c,h]xanthen-7-one (4). Procedure 1: A
mixture of 1 (78 mg, 0.25 mmol) and polyphosphoric
acid (10 ml) was heated and stirred at 100 ꢀC for

Efficient Synthesis of a New L-Shaped Dimer of Naphthalene
2637
(log "): 212 (4.30), 246 (3.59), 261 (3.68), 288 (3.78),
300 sh (3.47), 360 (3.11); NMR ꢀH (270 MHz, CDCl3):
7.72–7.80 (6H, m), 7.93–7.96 (2H, m), 8.32 (2H, d,
J ¼ 8:6 Hz), 8.79–8.83 (2H, m); EIMS m=z (rel. int. %):
297 (Mþ þ 1, 25), 296 (Mþ, 100), 268 (27), 239 (23),
237 (10), 134 (14), 120 (12), 40 (13); HREIMS
m=z (Mþ): Calcd. for C21H12O2: 296.0838, Found:
296.0850.
(5.14), 237 (5.17), 307 (4.48), 320 sh (4.42); NMR ꢀH
(500 MHz, CDCl3) and NMR ꢀC (125 MHz, CDCl3): see
Table 3; NMR ꢀH (500 MHz, C5D5N): 6.99–7.03 (1H,
m), 7.29 (1H, d, J ¼ 8:4 Hz), 7.53–7.56 (2H, m), 7.59
(1H, dd, J ¼ 7:7, 6.4 Hz), 7.92 (1H, d, J ¼ 8:4 Hz);
NMR ꢀC (125 MHz, C5D5N): 157.5, 136.5, 131.1, 129.8,
129.1, 126.8, 126.4, 119.8, 117.4, 102.7; EIMS m=z (rel.
int. %): 297 (Mþ þ 1, 21), 296 (Mþ, 100), 295 (47), 267
(11), 239 (16), 120 (14); HREIMS m=z (Mþ): Calcd. for
C21H12O2: 296.0838, Found: 296.0814.
Isomerization reaction of 3 in PPA. A mixture of 3
(70 mg, 0.24 mmol) and polyphosphoric acid (2 ml) was
heated and stirred at 100 ꢀC for 8 h. No spot except the
starting material was detected by TLC analysis.
General procedure for carboxylic acids (1, 10, and
11). A solution of ether (14–16, 1.00 mmol) and KOH
(10 mmol) in DMI (5 ml) was heated at 100–130 ꢀC for
0.5–4 h. After cooling, the mixture was quenched with
2 M aq. HCl (50 ml) and extracted with toluene (50 ml).
The organic layer was washed with brine and dried over
MgSO4. The solvent was removed under reduced
pressure, and the solid residue was washed with
hexane/CH2Cl2 to give acids 1, 10, and 11 as colorless
solids in 81, 78, and 80% yield respectively.
1: Colorless amorphous; m.p.: 171.2–172.2 ꢀC
(EtOH); IR ꢁmax (KBr) cmꢁ1: 3507 (br), 2363, 1704,
1596, 1573, 1506, 1464, 1394, 1368, 1248, 1211, 1107,
1047, 832, 791, 669; NMR ꢀH (270 MHz, CDCl3): 6.90
(1H, d, J ¼ 7:6 Hz), 7.05 (1H, d, J ¼ 7:6 Hz), 7.18 (1H,
d, J ¼ 6:9 Hz), 7.36 (1H, t, J ¼ 8:1 Hz), 7.38 (1H, t, J ¼
8:1 Hz), 7.45–7.67 (5H, m), 7.93 (2H, t, J ¼ 7:3 Hz),
8.26 (1H, d, J ¼ 8:3 Hz); NMR ꢀC (67.5 MHz, CDCl3)
113.5, 113.8, 122.2, 122.4, 123.2, 123.7, 125.4, 125.5,
125.9, 126.2, 126.6, 126.9, 127.7, 128.4, 130.0, 134.9,
135.2, 152.5, 153.0, 175.5; EIMS m=z (rel. int. %): 315
(Mþ þ 1, 23), 314 (Mþ, 100), 270 (10), 269 (44), 268
(25), 239 (15), 171 (12), 144 (22), 115 (37); HREIMS
m=z (Mþ): Calcd. for C21H14O3: 314.0943, Found:
314.0895.
8-(7-Methoxy-1-naphthalenyloxy)-1-naphthalenecar-
boxylic acid (10): Colorless prisms; m.p.: 222.1–
223.1 ꢀC (EtOH); IR ꢁmax (KBr) cmꢁ1: 3855, 3651,
3406 (br), 2362, 2341, 1700, 1652, 1559, 1542, 1509,
1287, 1106, 777, 669; NMR ꢀH (270 MHz, CDCl3): 3.81
(3H, s), 6.98 (2H, t, J ¼ 8:1 Hz), 7.14–7.25 (3H, m),
7.38 (1H, t like, J ¼ 7:9 Hz), 7.46–7.63 (4H, m), 7.78
(1H, d, J ¼ 9:1 Hz), 7.93 (1H, d, J ¼ 8:2 Hz); NMR ꢀC
(67.5 MHz, CDCl3): 55.3, 113.7, 113.9, 114.1, 119.8,
122.4, 123.2, 123.3, 123.4, 125.4, 125.5, 126.6, 127.9,
128.4, 129.3, 129.9, 130.4, 135.2, 151.6, 152.6, 158.0,
175.9; EIMS m=z (rel. int. %): 327 (½M ꢁ OHꢃþ, 24),
326 (½M ꢁ H2Oꢃþ, 99), 310 (11), 309 (35), 308 (29), 307
(12), 282 (34), 281 (79), 279 (11), 265 (14), 253 (13),
252 (27), 250 (15), 199 (55), 171 (16), 156 (15), 155
(100), 128 (28), 127 (76), 126 (29), 125 (12), 115 (24);
HREIMS m=z (½M ꢁ H2Oꢃþ): Calcd. for C22H14O3:
326.0943, Found: 326.0913.
8-Bromo-1-naphthyl 8-hydroxy-1-naphthyl ketone (8).
To a stirred solution of 5 (2.00 g, 7.00 mmol) in ether
(50 ml) cooled at ꢁ78 ꢀC was added dropwise over
5 min 2.6 M n-BuLi in hexane (2.70 ml, 7.10 mmol). The
solution was stirred at ꢁ78 ꢀC for 30 min, and added to a
solution of 7 (1.07 g, 6.30 mmol) in Et2O (20 ml) cooled
to 0 ꢀC. The resulting dark red suspension was stirred at
0 ꢀC for 30 min and then at room temperature for 2 h.
The reaction mixture was poured into 2 M aq. HCl
(50 ml) and extracted with EtOAc (50 ml). The organic
layer was washed with brine, dried over MgSO4, and
concentrated in vacuo. Purification of the residue
by column chromatography on SiO2 using hexane–
EtOAc (5:1) as eluent afforded 2.32 g (98%) of 8 as
an orange solid.
8: Orange prisms; m.p.: 164.0–166.0 ꢀC (EtOH); IR
ꢁmax (KBr) cmꢁ1: 3466, 1633, 1608, 1513, 1451, 1274,
1258, 821, 779, 767, 757; NMR ꢀH (270 MHz, CDCl3):
7.18–7.64 (9H, m), 7.80 (1H, d, J ¼ 7:8 Hz), 7.95 (1H,
d, J ¼ 7:9 Hz), 8.04 (1H, d, J ¼ 6:9 Hz), 11.10 (1H, s);
NMR ꢀC (67.5 MHz, CDCl3): 116.6, 119.7, 121.2, 122.3,
123.3, 125.2, 127.3, 128.4, 128.7, 129.2, 129.7, 131.5,
133.4, 135.7, 135.8, 136.5, 137.3, 138.5, 139.4, 154.8,
204.7; EIMS m=z (rel. int. %): 378 (Mþ þ 2, 30), 376
(Mþ, 30), 298 (25), 297 (100), 171 (11), 170 (12), 149
(18), 127 (11), 126 (11), 115 (11); HREIMS m=z (Mþ):
Calcd. for C21H13BrO2: 376.0099, Found: 376.0077.
2,20(2H,20H)-Spirobi[naphtho[1,8-bc]furan] (9). To a
solution of 8 (0.20 g, 0.52 mmol) and potassium carbo-
nate (0.11 g, 0.79 mmol) in degassed pyridine was added
Cu2O (7 mg, 0.05 mmol). The reaction mixture was
heated at reflux for 2 h, cooled to room temperature, and
concentrated in vacuo. The residue was dissolved in a
mixture of 2 M aq. HCl and EtOAc, and the water layer
was extracted with additional EtOAc. The combined
EtOAc layers were washed with brine, dried with
MgSO4, and concentrated in vacuo. Purification of
the residue by column chromatography on SiO2 using
CHCl3 as eluent afforded 0.12 g (74%) of 9 as a
colorless solid.
8-(4-Bromo-1-naphthalenyloxy)-1-naphthalenecarbox-
ylic acid (11): Colorless plates; m.p.: 257.0–259.5 ꢀC
(EtOH); IR ꢁmax (KBr) cmꢁ1: 3433 (br), 2363, 2341,
1699, 1600, 1594, 1507, 1468, 1456, 1421, 1372, 1296,
9: Amorphous; m.p.: 183.2–184.0 ꢀC (EtOH); IR ꢁmax
(KBr) cmꢁ1: 1618, 1603, 1491, 1467, 1368, 1293, 1167,
925, 854, 810, 769; UV ꢂmax (EtOH) nm (log "): 220 sh

2638
K. YOSHIOKA et al.
1241, 1203, 1156, 1101, 1052, 916, 837, 819, 766, 669;
NMR ꢀH (270 MHz, C5D5N): 6.95 (1H, d, J ¼ 8:3 Hz),
7.06–7.19 (2H, m), 7.20 (1H, d, J ¼ 6:9 Hz), 7.26 (1H, t,
J ¼ 6:9 Hz), 7.36–7.56 (1H, m), 7.64 (1H, d, J ¼ 8:3
Hz), 7.69 (1H, d, J ¼ 7:9 Hz), 7.83 (1H, d, J ¼ 6:3 Hz),
7.93 (1H, d, J ¼ 8:3 Hz), 8.09 (1H, d, J ¼ 8:6 Hz), 8.47
(1H, s), 8.54 (1H, d, J ¼ 8:3 Hz); NMR ꢀC (67.5 MHz,
CDCl3): 113.7, 116.9, 122.2, 122.3, 123.2, 123.8, 125.4,
125.5, 125.9, 126.2, 126.6, 126.9, 127.7, 129.0, 130.0,
135.0, 135.2, 152.4, 153.0, 174.5; EIMS m=z (rel. int.
%): 395 (Mþ þ 3, 23), 394 (Mþ þ 2, 99), 393 (Mþ þ 1,
23), 392 (Mþ, 100), 269 (15), 268 (54), 239 (14), 224
(23), 222 (23), 171 (23), 126 (13), 115 (34); HREIMS
m=z (Mþ): Calcd. for C21H1379BrO3: 392.0048, Found:
392.0061.
13: Yellow needles; m.p.: 230.0–232.0 ꢀC (EtOH); IR
ꢁmax (KBr) cmꢁ1: 2363, 1700, 1653, 1600, 1542, 1508,
1458, 1348, 1239, 758, 669; NMR ꢀH (500 MHz,
C5D5N): 7.56 (1H, t, J ¼ 7:9 Hz), 7.61 (1H, t, J ¼
7:7 Hz), 7.72 (1H, td, J ¼ 6:9, 1.7 Hz), 7.75 (1H, td,
J ¼ 6:9, 1.7 Hz), 7.83 (1H, dd, J ¼ 7:9, 1.2 Hz), 7.86
(1H, dd, J ¼ 7:9, 1.2 Hz), 8.15 (1H, dd, J ¼ 7:7, 1.5
Hz), 8.16 (1H, s), 8.23 (1H, dd, J ¼ 6:9, 1.7 Hz), 8.56
(1H, dd, J ¼ 7:7, 1.5 Hz), 8.86 (1H, dd, J ¼ 6:9, 1.7
Hz); NMR ꢀC (500 MHz, C5D5N): 118.9, 119.5, 123.1,
123.9, 124.4, 125.5, 126.5, 126.6, 127.3, 127.7, 128.5,
128.9, 130.3, 130.4, 131.0, 132.9, 135.1, 135.9, 136.3,
153.5, 191.8: EIMS m=z (rel. int. %): 377 (Mþ þ 3, 23),
376 (Mþ þ 2, 100), 375 (Mþ þ 1, 24), 374 (Mþ, 98),
348 (36), 346 (37), 267 (10), 239 (43), 238 (13), 237
(29), 174 (15), 173 (14), 120 (22), 119 (17); HREIMS
m=z (Mþ): Calcd. for C21H1179BrO2: 373.9942, Found:
373.9901.
14H-9-Methoxy-dinaphtho[1,8-bc:10,20-f]oxepin-14-one
(12). To a suspension of 10 (0.50 g, 1.45 mmol) in
CH2Cl2 (5 ml) was added trifluoroacetic anhydride (0.32
ml, 2.25 mmol) at 0 ꢀC, and to the resulting yellow
solution was added trifluoromethanesulfonic acid (13 ml,
0.15 mmol). After 1 min, the reaction mixture was
poured into 2 M aq. HCl and extracted with CHCl3. The
organic layer was washed with brine, dried over MgSO4,
and concentrated in vacuo. Purification of the residue by
column chromatography on SiO2 using CHCl3 as eluent
afforded 0.45 g (97%) of 12 as yellow solid.
12: Yellow needles; m.p.: 147.2–149.0 ꢀC (EtOH); IR
ꢁmax (KBr) cmꢁ1: 2363, 2341, 1655, 1609, 1559, 1508,
1459, 1219, 1124, 1033, 843, 772, 745, 669; NMR ꢀH
(270 MHz, CDCl3): 4.09 (3H, s), 7.27 (1H, d, J ¼ 8:6
Hz), 7.48–7.77 (7H, m), 8.03 (1H, d, J ¼ 7:3 Hz), 8.05
(1H, d, J ¼ 8:1 Hz), 8.41 (1H, d, J ¼ 7:3 Hz); NMR ꢀH
(500 MHz, C5D5N): 3.96 (3H, s), 7.40 (1H, dd, J ¼ 8:9,
2.6 Hz), 7.55 (1H, dd, J ¼ 8:2, 7.3 Hz), 7.58 (1H, dd,
J ¼ 8:1, 7.4 Hz), 7.70 (1H, d, J ¼ 8:4 Hz), 7.77 (1H, d,
J ¼ 8:4 Hz), 7.80 (1H, dd, J ¼ 8:2, 1.5 Hz), 7.85 (1H, d,
J ¼ 8:9 Hz), 7.94 (1H, dd, J ¼ 7:3, 1.5 Hz), 8.11 (1H,
dd, J ¼ 8:1, 1.5 Hz), 8.21 (1H, d, J ¼ 2:6 Hz), 8.54 (1H,
dd, J ¼ 7:4, 1.5 Hz); NMR ꢀC (67.8 MHz, CDCl3):
193.9, 158.6, 153.5, 151.9, 135.7, 134.3, 133.3, 132.3,
130.2, 130.1, 129.5, 127.7, 126.3, 125.9, 125.6, 125.5,
124.6, 122.5, 121.0, 118.6, 101.5, 55.5; EIMS m=z (rel.
int. %): 327 (Mþ þ 1, 24), 326 (Mþ, 100), 298 (19), 255
(23); HREIMS m=z (Mþ): Calcd. for C22H14O3:
326.0943, Found: 326.0954.
Isopropyl 8-(1-naphthalenyloxy)-1-naphthalenecarbox-
ylate (14). To a mixture of isopropyl 8-iodonaphthale-
necarboxylate4) (0.50 g, 1.47 mmol), 1-naphthol (0.32 g,
2.21 mmol), and potassium carbonate (0.34 g, 2.50
mmol) in degassed pyridine (10 ml) was added Cu2O
(21 mg, 0.15 mmol). The reaction mixture was heated at
reflux for 4 h, cooled to room temperature, and concen-
trated in vacuo. Purification of the residue by column
chromatography on SiO2 using hexane–EtOAc (20:1) as
eluent afforded 0.28 g (55%) of 14 as a colorless solid.
14: Colorless plates; m.p.: 123.0–124.5 ꢀC (EtOH); IR
ꢁmax (KBr) cmꢁ1: 2983, 2363, 2341, 1717, 1653, 1623,
1596, 1573, 1541, 1506, 1461, 1389, 1346, 1286, 1242,
1204, 1175, 1148, 1111, 1098, 1079, 1044, 844, 832,
806, 770, 670, 41; NMR ꢀH (270 MHz, CDCl3): 1.05
(6H, d, J ¼ 6:3 Hz), 4.95 (1H, sept, J ¼ 6:3 Hz), 6.76
(1H, d, J ¼ 7:6 Hz), 7.12 (1H, d, J ¼ 7:6 Hz), 7.31 (1H,
t, J ¼ 7:9 Hz), 7.39–7.60 (6H, m), 7.68 (1H, d, J ¼ 7:9
Hz), 7.88 (1H, d, J ¼ 7:9 Hz), 7.94 (1H, d, J ¼ 7:6 Hz),
8.18 (1H, d, J ¼ 8:2 Hz); NMR ꢀC (67.5 MHz, CDCl3):
21.5, 69.0, 112.5, 115.1, 121.9, 122.4, 122.8, 124.1,
125.2, 125.5, 125.8, 126.1, 126.4, 126.6, 127.0, 127.7,
129.3, 130.4, 134.9, 135.2, 152.1, 153.8, 170.3; EIMS
m=z (rel. int. %): 357 (Mþ þ 1, 26), 356 (Mþ, 100),
314 (10), 297 (21), 270 (12), 269 (53), 268 (29), 239 (17),
171 (49), 144 (21), 127 (11), 115 (17); HREIMS m=z
(Mþ): Calcd. for C24H20O3: 356.1413, Found: 356.1369.
14H-12-Bromo-dinaphtho[1,8-bc:10,20-f]oxepin-14-one
(13). To a suspension of 11 (150 mg, 0.38 mmol) in
CH2Cl2 (10 ml) was added trifluoroacetic anhydride
(67 ml, 0.57 mmol) at 0 ꢀC, and to the resulting yellow
solution was added trifluoromethanesulfonic acid (4 ml,
0.04 mmol). After 1 min, the reaction mixture was
poured into 2 M aq. HCl and extracted with CHCl3. The
organic layer was washed with brine, dried over MgSO4,
and concentrated in vacuo. Purification of the residue by
column chromatography on SiO2 using CHCl3 as eluent
afforded 130 mg (91%) of 13 as a yellow solid.
Isopropyl 8-(7-methoxy-1-naphthalenyloxy)-1-naph-
thalenecarboxylate (15). To a mixture of isopropyl
8-iodonaphthalenecarboxylate (6.50 g, 19.1 mmol), 7-
methoxy-1-naphthol14) (4.99 g, 28.6 mmol), and potassi-
um carbonate (3.95 g, 28.6 mmol) in degassed pyridine
(100 ml) was added Cu2O (273 mg, 1.91 mmol). The
reaction mixture was heated at reflux for 5 h, cooled to
room temperature, and concentrated in vacuo. Purifica-
tion of the residue by column chromatography on SiO2
using toluene as eluent afforded 3.45 g (47%) of 15 as a
colorless solid.

Efficient Synthesis of a New L-Shaped Dimer of Naphthalene
2639
15: Colorless prisms; m.p.: 125.5–127.2 ꢀC (EtOH);
IR ꢁmax (KBr) cmꢁ1: 3855, 3676, 3651, 2362, 2341,
1716, 1653, 1634, 1603, 1559, 1541, 1507, 1376, 1344,
1286, 1214, 1202, 1024, 987, 833, 768, 669, 419; NMR
ꢀH (270 MHz, CDCl3): 1.04 (6H, br), 3.82 (3H, s), 4.98
(1H, sept, J ¼ 6:3 Hz), 6.83 (1H, d, J ¼ 7:7 Hz), 7.12–
7.62 (9H, m), 7.77 (1H, d, J ¼ 9:1 Hz), 7.93 (1H, dd,
J ¼ 7:9, 1.3 Hz); NMR ꢀC (67.5 MHz, CDCl3) 21.6,
55.4, 69.1, 100.3, 112.3, 115.6, 119.8, 122.0, 122.7,
123.3, 123.9, 125.1, 125.6, 126.5, 128.3, 129.3, 129.4,
130.5, 130.6, 135.3, 151.2, 153.6, 158.0, 170.6; EIMS
m=z (rel. int. %): 387 (Mþ þ 1, 27), 386 (Mþ, 100), 299
(11), 174 (11), 171 (19), 158 (10); HREIMS m=z (Mþ):
Calcd. for C25H22O4: 386.1519, Found: 386.1474.
Agriculture, Hokkaido University for their skill and
assistance in measuring MS spectra.
References
´
1) Seco, J. M., Quin˜oa, E., and Riguera, R., The assignment
of absolute configuration by NMR. Chem. Rev., 104, 17–
117 (2004).
2) Fukushi, Y., Yajima, C., and Mizutani, J., A new method
for establishment of absolute configurations of secondary
alcohols by NMR spectroscopy. Tetrahedron Lett., 35,
599–602 (1994).
3) Fukui, H., Fukushi, Y., and Tahara, S., NMR determi-
nation of the absolute configuration of cyclic chiral
alkenes. Tetrahedron Lett., 40, 325–328 (1999).
4) Fukui, H., Fukushi, Y., and Tahara, S., NMR determi-
nation of the absolute configuration of chiral 1,2- and
1,3-diols. Tetrahedron Lett., 44, 4063–4065 (2003).
5) Terajima, M., Cai, J., and Lim, E. C., Time-resolved
RPR and optical studies of intermoiety interaction in the
lowest triplet state of L-shaped dimers of naphthalene.
J. Phys. Chem. A, 104, 1662–1669 (2000).
6) Kubo, M., and Sato, T., Peri interaction in naphthalene
ketones. Bull. Chem. Soc. Jpn., 52, 3314–3317 (1979).
7) Van Allan, J. A., and Stenberg, J. F., A convenient
synthesis of certain benzo and dibenzoxanthones and
chromones. J. Heterocycl. Chem., 16, 1663–1665 (1979).
8) Tsuji, R., Komatsu, K., Inoue, Y., and Takeuchi, K.,
1-Naphthyltropylium ions having condensed aromatic
rings at the 8-position: dependence of the intramolecular
charge-transfer interaction upon geometry of the donor.
J. Org. Chem., 57, 636–641 (1992).
9) Kuroda, M., Nakayama, J., and Hoshino, M., Synthesis
and properties of 1,8-Di(2-thienyl)-, 1,8-bis(5,20-bithio-
phene-2-yl)-, 1,8-bis(5,20:50,200-terthiophene-2-yl)-, and
1,8-bis(5,20:50,200:500,2000-quaterthiophene-2-yl)naphthalenes
and related compounds. Tetrahedron, 49, 3735–3748
(1993).
10) Talbiersky, J., Pingen, H., Langenkamp, M., and
Schaeferling, H., Ger. Offen. 3417278 (Nov. 14, 1985).
11) Sawyer, J. S., Recent advances in diaryl ether synthesis.
Tetrahedron, 56, 5045–5065 (2000).
Isopropyl 8-(4-bromo-1-naphthalenyloxy)-1-naphtha-
lenecarboxylate (16). To a stirred solution of 14
(200 mg, 0.56 mmol) in CH2Cl2 (10 ml) was added
dropwise over 15 min N-bromosuccinimide (100 mg,
0.56 mmol) in CH2Cl2 (50 ml). After 6 h, the reaction
mixture was poured into saturated Na2SO3 solution and
extracted with CHCl3. The organic layer was washed
with brine, dried over MgSO4, and concentrated in
vacuo. Purification of the residue by column chroma-
tography on SiO2 using hexane–EtOAc (20:1) as eluent
afforded 237 mg (99%) of 16 as a colorless solid.
16: Colorless plates; m.p.: 96.7–97.2 ꢀC (EtOH); IR
ꢁmax (KBr) cmꢁ1: 2986, 2363, 2341, 1706, 1624, 1600,
1593, 1579, 1461, 1420, 1375, 1349, 1282, 1243, 1198,
1152, 1107, 1052, 1021, 987, 918, 850, 831, 811, 766,
670, 417; NMR ꢀH (270 MHz, CDCl3): 1.06 (6H, d,
J ¼ 6:2 Hz), 4.91 (1H. sept, J ¼ 6:2 Hz), 6.79 (1H, d,
J ¼ 7:6 Hz), 6.98 (1H, d, J ¼ 8:2 Hz), 7.33 (1H, t, J ¼
7:9 Hz), 7.51–7.72 (5H, m), 7.94 (1H, d, J ¼ 7:6 Hz),
8.22–8.27 (2H, m); NMR ꢀC (67.5 MHz, CDCl3): 21.6,
69.1, 113.0, 115.4, 117.5, 122.0, 122.9, 123.4, 125.5,
125.7, 126.4, 127.0, 127.2, 128.1, 128.2, 129.5, 129.6,
130.3, 133.1, 135.3, 152.2, 153.4, 170.3; EIMS m=z (rel.
int. %): 437 (Mþ þ 3, 25), 436 (Mþ þ 2, 97), 435
(Mþ þ 1, 25), 434 (Mþ, 96), 392 (11), 377 (10), 296
(11), 269 (19), 268 (70), 239 (27), 237 (10), 224 (19),
172 (12), 171 (100), 170 (14), 126 (14), 115 (24);
HREIMS m=z (Mþ): Calcd. for C24H1979BrO3:
434.0518, Found: 434.0487.
12) Chow, Y. N., Zhao, D. C., and Johansson, C. I., The inter-
mediates in the interaction of phenols with N-bromosuc-
cinimide. Can. J. Chem., 66, 2556–2564 (1988).
13) Lansbury, P. T., and Klein, M., Restricted conforma-
tional inversion in 1,8-(1,8-naphthyldimethyl)naphtha-
lene. Tetrahedron Lett., 16, 1981–1984 (1968).
14) Bell, K. H., and McCaffery, L. F., Regioselective
monomethylation of unsymmetrical naphthalenediols
with methanolic hydrogen chloride. Aust. J. Chem., 46,
731–737 (1993).
Acknowledgments
We are grateful to Mr. Kenji Watanabe and Dr. Eri
Fukushi of the GC-MS and NMR Laboratory, Faculty of