A simple and versatile synthesis of 1,2-diarylacenaphthylenes via Suzuki-Miyaura coupling, and its application in the synthesis of a new acenaphthylene-1,2-bis(p-quinone methide) derivative

Article abstract of DOI:10.1055/s-2007-984897

1,2-Diaryl-substituted acenaphthylene derivatives were prepared simply via Suzuki-Miyaura coupling in good or excellent yields. By applying this method, acenaphthylene-1,2-bis(p-quinone methide) with two 3,5-di-tert-butyl-4- oxocyclohexadienylidene units,

Full text of DOI:10.1055/s-2007-984897

LETTER
2053
A Simple and Versatile Synthesis of 1,2-Diarylacenaphthylenes via
Suzuki–Miyaura Coupling, and its Application in the Synthesis of a New
Acenaphthylene-1,2-bis(p-quinone methide) Derivative
S
ynthesis of 1,2-D
i
iaryla
c
r
o
lene
s
yuki Kurata,* Yuko Takehara, Sang Kim, Kanae Sakai, Kouzou Matsumoto, Takeshi Kawase, Masaji Oda
Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
Fax +81(6)68505387; E-mail: kurata@chem.sci.osaka-u.ac.jp
Received 18 May 2007
HO
tBu tBu
OH
Abstract: 1,2-Diaryl-substituted acenaphthylene derivatives were
prepared simply via Suzuki–Miyaura coupling in good or excellent
yields. By applying this method, acenaphthylene-1,2-bis(p-quinone
methide) with two 3,5-di-tert-butyl-4-oxocyclohexadienylidene
units, which is a stable deep purple crystalline substance with a very
broad absorption in the whole visible region and relatively low
reduction potential, was prepared and characterized.
Ar
Ar
tBu
tBu
1
Key words: arenes, chromophores, cross-coupling, quinines,
Suzuki reaction
2
O
tBu tBu
O
tBu
tBu
Acenaphthylene is one of the most fundamental
molecules in the family of cyclopentene-fused polycyclic
aromatic hydrocarbons (CPAH). A large number of deriv-
atives have been prepared; these have recently attracted
interest as synthetic intermediates for curve-shaped
PAHs1 and also in the preparation of aryl-substituted lad-
der-type CPAHs.2 Several 1,2-diaryl-substituted acenaph-
thylenes 1 have been reported, but most of the syntheses
were multistep procedures beginning with nucleophilic
addition of arylmetals (ArLi or ArMgBr) to 1,2-acenaph-
thenquinone, and the total yields were not high.3 During
the course of our recent studies concerning novel non-
planar extended quinonoid systems,4 we planned to pre-
pare the extended acenaphthenequinone 3 via oxidation of
the bisphenol-substituted acenaphthylene 2 (Figure 1). A
synthetic study of 2 revealed that 1,2-diarylacenaphthyl-
enes could be prepared efficiently via Suzuki–Miyaura
coupling using 1,2-dibromoacenaphthylene (4) as a start-
ing material.
3
Figure 1
reaction of 4 with several arylboronic acids under the
same conditions; the results are shown in Table 1.
As shown in Table 1, various 1,2-diarylacenaphthylene
derivatives were prepared in good or excellent yields.
Br
Br
Ar
Ar
10 mol% Pd(PPh3)4
+
ArB(OH)2
6 equiv K2CO3
DME–H2O (2:1)
reflux 18 h
(3.0 equiv)
1
4
Although there are numerous examples of aryl–aryl bond
formation from aryl halides (ArX) by transition-metal-
catalyzed cross-coupling,5 syntheses using 4 have not yet
been reported.6,7 Therefore, we examined Suzuki–
Miyaura coupling of 4 with arylboronic acids (Scheme 1).
Compound 4 was readily prepared by bromination of
acenaphthylene with N-bromosuccinimide.8
Scheme 1 Synthesis of 1 via Suzuki–Miyaura coupling.
Table 1 Suzuki–Miyaura Coupling of 4 with Arylboronic Acids
Entry
Ar
Yield of 1 (%)
85 (1a)
1
2
3
4
5
6
Ph
The reaction of 4 with 3.0 equivalents of phenylboronic
acid was attempted using Pd(PPh3)4 as a catalyst and
aqueous K2CO3 as a base under refluxing DME for 18
hours. After a typical workup, 1,2-diphenylacenaphthyl-
ene (1a) was isolated in 85% yield. We also examined the
4-MeOC6H4
4-FC6H4
2-Thienyl
2-MeC6H4
1-Naphthyl
96 (1b)
82 (1c)
94 (1d)
93 (1e)
SYNLETT 2007, No. 13, pp 2053–2056
1
3
.0
8
.2
0
0
7
87 (1f)
Advanced online publication: 12.07.2007
DOI: 10.1055/s-2007-984897; Art ID: U05207ST
© Georg Thieme Verlag Stuttgart · New York

2054
H. Kurata et al.
LETTER
Electron-rich and electron-poor aromatic rings, as well as
heteroaromatic rings, were introduced successfully
(entries 2, 3, and 4). It is noteworthy that ortho-substituted
arylboronic acids, such as 2-methylphenylboronic acid
and 1-naphthylboronic acid, reacted cleanly to afford the
coupling products 1e and 1f, respectively (entries 5 and
6).9 Taking into account the high availability of aryl-
boronic acids, this is, to our knowledge, the most efficient
way of preparing 1,2-diarylacenaphthylenes, with few
steps and high chemical yields.
OH
tBu
tBu
10 mol% Pd(PPh3)4
4
+
6 equiv K2CO3
DME–H2O (2:1)
reflux, 18 h
98%
B
HO
OH
5
(3.0 equiv)
tBu tBu
OH
O
tBu tBu
O
HO
Figure 2 ORTEP drawing of unit cell of 3 (50% thermal ellipsoids).
Hydrogen atoms are omitted for clarity.
tBu
tBu
tBu
tBu
1.2 equiv DDQ
The UV/Vis spectra of 2 and 3 in cyclohexane are shown
in Figure 3. While compound 2 has a strong absorption
maximum at l = 238 nm (log e = 4.74) and a weak ab-
sorption around l = 458 nm (log e = 3.52), compound 3
has relatively high absorbance in the whole visible region,
and therefore its color in concentrated solution is nearly
black.
toluene
r.t., 1 h
83%
3
2
Scheme 2 Synthesis of bisphenol 2 and quinone 3.
The redox properties of these compounds were studied
using cyclic voltammetry.14 Two sets of reversible reduc-
tion waves were observed for 3 on electronic reduction
On the basis of these results, the synthesis of bisphenol 2
was carried out using 3,5-di-tert-butyl-4-hydroxyphenyl-
boronic acid (5).10 Compound 2 was obtained as reddish-
orange crystals in 98% yield. Successive oxidation of 2 by
DDQ in toluene at room temperature for 1 hour afforded
quinone 3 in 86% yield (Scheme 2).
2
(1E1/2 = –0.81V, E1/2 = –1.19 V, vs. Fc/Fc+), which in-
dicates formation of an anion radical and a dianion. Due
to p-extension, these reduction potentials are much lower
than those of 1,2-acenaphthenequinone (1E1/2 = –1.35 V,
2E1/2 = –2.33 V, vs. Fc/Fc+). This redox behavior is
similar to that of pyracylene-extended quinone 6.4e The
Compound 3 is a dark-purple crystalline substance with
thermal and air stability. The molecular structure of 3 was
determined by X-ray crystallographic analysis (Figure
2).12 Two independent molecules are present in the unit
cell; these are stacked head-to-tail at the acenaphthene
moieties to form a dimer structure, and the distance at the
dimer is 3.57 Å. The acenaphthylene skeleton is almost
planar, and the averaged dihedral angle of the two pinch
bonds is 29.9°. The pinch bonds are twisted in a range be-
tween 11.2° and 30.6° in order to avoid steric crowding
around the quinone methide units.
1
Sharp and well-resolved signals were observed in the H
NMR spectrum of 3, which reflected negligible contribu-
tion of the diradical structure in 3. At room temperature,
the quinone methide protons and the tert-butyl protons are
observed as a set of doublets (d = 8.19 and 7.14 ppm,
J = 2.0 Hz) and two singlets (d = 1.46 and 1.21 ppm),
respectively. The rotational barrier of the pinch bonds was
estimated to be 17.4 kcal/mol by variable-temperature
NMR measurements based on the coalescence of the tert-
butyl protons.13
Figure 3 UV/Vis spectra of 2 (dashed line) and 3 (solid line) in
cyclohexane.
Synlett 2007, No. 13, 2053–2056 © Thieme Stuttgart · New York

LETTER
Synthesis of 1,2-Diarylacenaphthylenes
1,2-Di(2-thienyl)acenaphthylene (1d)
Yield 94%; reddish-orange crystals; mp 140–141 °C. MS (EI): m/z
(%) = 316 (100) [M+]. 1H NMR (270 MHz, CDCl3): d = 7.84–7.87
(m, 4 H), 7.59 (m, 2 H), 7.40 (dd, J = 5.1, 1.2 Hz, 2 H), 7.27 (dd,
J = 3.6, 1.2 Hz, 2 H), 7.12 (dd, J = 5.1, 3.6 Hz, 2 H). 13C NMR (67.8
MHz, CDCl3): d = 139.65, 136.27, 131.75, 128.24, 127.85 (2 C),
127.57, 127.24, 126.37, 124.11, 100.48. Anal. Calcd for C20H12S2:
C, 75.91; H, 3.82. Found: C, 75.81; H, 3.91.
2055
O
tBu tBu
O
O
tBu t
Bu
O
tBu
tBu
tBu
tBu
1,2-Di(2-methylphenyl)acenaphthylene (1e)
7
Yield 93%; orange powder (lit.3c thick orange-red oil); mp 46–
6
47 °C. MS (EI): m/z (%) = 332 (100) [M+], 317 (26) [M – CH3]+,
Figure 4
1
239 (43). H NMR (270 MHz, CDCl3, mixture of two isomers):
d = 7.84 (dd, J = 8.0, 0.7 Hz, 2 H), 7.83 (dd, J = 8.1, 0.8 Hz, 2 H),
7.44–7.58 (m, 8 H), 7.09–7.30 (m, 16 H), 2.17 (s, 6 H), 2.04 (s,
6 H). 13C NMR (67.8 MHz, CDCl3, mixture of two isomers): d =
140.75, 140.58, 139.52, 139.38, 136.82, 136.40, 135.03, 134.66,
130.92, 130.27, 130.25, 130.17, 128.21, 128.17, 128.08, 127.70,
127.64, 127.28, 126.91, 126.89, 125.37, 125.23, 123.76, 123.53,
20.78, 20.73.
reversibility is attributed to its rigid structure, similarly to
that of 6, while phenanthrene-extended quinone 7 shows
lower reversibility because of its relatively flexible
structure (Figure 4).4c
1,2-Di(1-naphthyl)acenaphthylene (1f)
General Procedure for Synthesis of 1,2-Diarylacenaphthylenes
(1a–f and 2)
Yield 87%; orange crystals; mp 264–266 °C (lit.7 268–270 °C). MS
(EI): m/z (%) = 404 (100) [M+], 276 (18). H NMR (270 MHz,
1
A two-necked, round-bottomed flask equipped with a stirring bar, a
rubber septum, a reflux condenser, and a N2 balloon was charged
with 1,2-dibromoacenaphthylene (4, 0.4 mmol), boronic acid (1.2
mmol), K2CO3 (3 mmol), and Pd(PPh3)4 (10 mol%). Then DME (10
mL) and H2O (5 mL) were added through a rubber septum. The re-
action mixture was stirred and refluxed for 18 h. After cooling to
r.t., the mixture was poured into 2 M HCl and extracted with Et2O
(3 × 20 mL). The combined organic layer was washed with H2O and
brine, and dried over anhyd Na2SO4. After removal of the solvent,
the residue was purified by column chromatography on silica gel
using CH2Cl2–hexane as eluent to give 1.
CDCl3, mixture of two isomers): d = 8.04–8.11 (m, 4 H), 7.82–7.91
(m, 6 H), 7.69–7.76 (m, 6 H), 7.43–7.58 (m, 10 H), 7.26–7.39 (m, 8
H), 7.21–7.24 (m, 4 H), 7.08–7.14 (m, 2 H). 13C NMR (67.8 MHz,
CDCl3, mixture of two isomers): d = 141.17, 141.06, 139.99,
139.13, 133.58, 133.52, 133.24, 132.91, 132.82, 131.94, 128.32,
128.28, 128.20, 128.18, 128.02, 127.88, 127.81, 127.75, 127.72,
127.67, 127.22, 127.18, 126.93, 126.64, 125.56, 125.46, 125.41,
125.24, 124.99, 124.39, 124.31.
1,2-Bis(3,5-di-tert-butyl-4-hydroxyphenyl)acenaphthylene (2)
Yield 98%; reddish-orange crystals; mp 244–245 °C. MS (EI): m/z
1
(%) = 560 (100) [M+]. H NMR (270 MHz, CDCl3): d = 7.80 (d,
1,2-Diphenylacenaphthylene (1a)
J = 8.1 Hz, 2 H), 7.71 (d, J = 6.9 Hz, 2 H), 7.56 (dd, J = 8.1, 6.9 Hz,
2 H), 7.23 (s, 4 H), 5.17 (s, 2 H), 1.37 (s, 36 H). 13C NMR (67.8
MHz, CDCl3): d = 152.67, 140.43, 138.11, 135.64, 128.30, 128.25,
127.63, 126.71, 126.62, 126,60, 123.21, 34.36, 30.44. IR (KBr): n =
3634 (s), 2957 (s), 1428 (s), 1399 (m), 1389 (m), 1358 (m), 1315
(m), 1234 (s), 1206 (m), 1157 (s), 1119 (m), 1034 (w), 909 (w), 889
(m), 868 (w), 823 (s), 769 (s), 651 (m) cm–1. UV/Vis (cyclohexane):
Yield 85%; orange crystals; mp 159–160 °C (lit.15 162–163 °C). MS
(EI): m/z (%) = 304 (100) [M+]. 1H NMR (270 MHz, CDCl3): d =
7.86 (d, J = 8.0 Hz, 2 H), 7.74 (d, J = 7.0 Hz, 2 H), 7.60 (dd, J = 8.0,
7.0 Hz, 2 H), 7.45 (m, 4 H), 7.30–7.39 (m, 6 H). 13C NMR (67.8
MHz, CDCl3): d = 139.88, 138.02, 135.16, 129.97, 128.34, 128.27,
128.15, 127.72, 127.20, 127.01, 123.89.
l
max (log e) = 458 (3.52), 356 (sh, 3.99), 340 (4.24), 328 (sh, 4.15),
1,2-Di(4-methoxyphenyl)acenaphthylene (1b)
294 (sh, 4.18), 280 (4.22), 254 (4.22), 238 (4.88). Anal. Calcd for
C40H48O2: C, 85.67; H, 8.63. Found: C, 85.39; H, 8.68.
Yield 96%; red crystals; mp 106–107 °C (lit.3e 122 °C). MS (EI):
m/z (%) = 364 (100) [M+]. 1H NMR (270 MHz, CDCl3): d = 7.82 (d,
J = 8.1 Hz, 2 H), 7.69 (d, J = 6.9 Hz, 2 H), 7.56 (dd, J = 8.1, 6.9 Hz,
2 H), 7.38 (AA¢BB¢, J = 8.9 Hz, 4 H), 6.90 (AA¢BB¢, J = 8.9 Hz, 4
H), 3.83 (s, 6 H). 13C NMR (67.8 MHz, CDCl3): d = 158.56, 140.20,
136.82, 131.06, 128.23, 128.16, 127.72, 127.64, 126.85, 123.42,
113.83, 55.24. Anal. Calcd for C26H20O2: C, 85.69; H, 5.53. Found:
C, 85.54; H, 5.55.
1,2-Bis(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadien-1-ylidene)-
1,2-dihydroacenaphthylene (3)
A 50 mL two-necked, round-bottomed flask equipped with a stir-
ring bar and a drying tube packed with CaCl2 was charged with
bisphenol 2 (115 mg, 0.2 mmol), DDQ (58 mg, 0.24 mmol), and tol-
uene (10 mL). The reaction mixture was stirred at r.t. for 1 h. The
solvent was removed under reduced pressure, and the residue was
purified by column chromatography on silica gel using CH2Cl2–
hexane = 1:5 as eluent to give 3 (91 mg, 83%).
1,2-Di(4-fluorophenyl)acenaphthylene (1c)
Yield 83%; orange crystals; mp 155–156 °C. MS (EI): m/z (%) =
1
340 [M+]. H NMR (270 MHz, CDCl3): d = 7.85 (dd, J = 8.1, 0.7
Deep-purple crystals; mp 238–239 °C. MS (EI): m/z (%) = 560 (69)
[M + 2 H]+, 559 (43) [M + H]+, 558 (100) [M+]. 1H NMR (270 MHz,
CDCl3): d = 8.19 (d, J = 2.0 Hz, 2 H), 8.08 (d, J = 7.4 Hz, 2 H), 7.87
(d, J = 8.1 Hz, 2 H), 7.70 (dd, J = 8.1, 7.4 Hz, 2 H), 7.14 (d, J = 2.0
Hz, 2 H), 1.46 (s, 18 H), 1.21 (s, 18 H). 13C NMR (67.8 MHz,
CDCl3): d = 186.34, 149.71, 148.31, 147.99, 136.72, 136.46,
135.94, 132.33, 130.67, 128.39, 127.84, 127.39, 122.99, 36.20,
35.58, 29.94, 29.58. IR (KBr): n = 3528 (m), 3443 (w), 2958 (s),
1595 (s, C=O), 1361 (m), 766 (m) cm–1. UV/Vis (cyclohexane):
lmax (log e) = 537 (4.04), 377 (4.60), 270 (4.14). Anal. Calcd for
C40H46O2: C, 85.98; H, 8.30. Found: C, 86.29; H, 8.22.
Hz, 2 H), 7.68 (dd, J = 6.9, 0.7 Hz, 2 H), 7.58 (dd, J = 8.1, 6.9 Hz,
2 H), 7.37 (m, JH–F = 5.4 Hz, 4 H), 7.05 (tt, J = 8.8, 2.1 Hz, 4 H). 13
C
NMR (67.8 MHz, CDCl3): d = 161.97 (d, JC–F = 246.5 Hz), 139.56,
137.01, 131.48 (d, JC–F = 7.8 Hz), 130.92 (d, JC–F = 3.3 Hz), 128.35,
127.95, 127.77, 127.41, 123.75, 115.46 (d, JC–F = 21.8 Hz). Anal.
Calcd for C24H14F2: C, 84.69; H, 4.15. Found: C, 84.34; H, 4.17.
Synlett 2007, No. 13, 2053–2056 © Thieme Stuttgart · New York

2056
H. Kurata et al.
LETTER
(7) Recently, Dyker et al. reported a Heck-type reaction of a
Acknowledgment
parent acenaphthylene with 1-bromonaphthalene to afford a
bisnaphthylated product in 19% yield: Dyker, G.; Merz, K.;
Oppel, I. M.; Muth, E. Synlett 2007, 897.
This work was supported by a Grant-in-Aid for Scientific Research
(No. 16550036) from the Ministry of Education, Culture, Sports,
Science, and Technology of Japan. We thank Prof. Takashi Kubo
(Graduate School of Science, Osaka University) for helpful discus-
sions.
(8) Trost, B. M.; Brittelli, D. R. J. Org. Chem. 1967, 32, 2620.
(9) In agreement with literature reports,3c,7 1H NMR spectra of
1e and 1f show the presence of 1:1 mixtures of rotational
isomers.
(10) Boronic acid 5 was prepared by reaction of 4-bromo-2,6-di-
tert-butylphenol with tert-BuLi (3 equiv)11 and subsequently
with tri(isopropoxy)borane (4 equiv). Compound 5 was
obtained as a mixture with the corresponding boroxane
formed by dehydration.
References and Notes
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Compound 5: white powder. 1H NMR (270 MHz, CDCl3):
d = 7.54 (s, 2 H), 5.48 (s, 1 H), 4.40 (s, 2 H), 1.47 (s 18 H).
The boroxane: white powder. 1H NMR (270 MHz, CDCl3):
d = 8.10 (s, 6 H), 5.59 (s, 3 H), 1.53 (s, 54 H). The
trimethylsilyl-protected derivative of 5 was synthesized by
Satoh et al.: Satoh, Y.; Shi, C. Synthesis 1994, 1146.
(11) Kurata, H.; Tanaka, T.; Sauchi, T.; Kawase, T.; Oda, M.
Chem. Lett. 1997, 947.
(12) Crystallographic data of 3: C40H46O2, M = 558.80,
monoclinic, P21/c, a = 21.040 (9), b = 13.717 (6),
c = 24.053 (10) Å, b = 103.24 (4)°, V = 6757 (17) Å3, Z = 8,
Dc = 1.098 g cm–3, 64264 reflections measured, 15373
unique (Rint = 0.145) used in refinement. R1 = 0.058 [I >
2s(I)], wR = 0.155 (all data). T = 200 K. X-ray data have
been deposited at the Cambridge Crystallographic Data
Centre (CCDC-649872). Copies of the data can be obtained
free of charge at www.ccdc.cam.uk/data_request/cif or from
the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ [fax: +44 (1223)336033; e-mail:
deposit@ccdc.cam.ac.uk].
(13) Variable-temperature NMR measurement of 3 was
performed in a bromobenzene-d5 solution. The coalescence
temperature of the tert-butyl signals was 78 3 °C.
(14) Measurements were carried out in DMF solution at r.t. using
a glassy carbon electrode with tetrabutylammonium
perchlorate as the supporting electrolyte.
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(6) Nickel and platinum complexes of 4 have been reported:
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(15) Richter, F. J. Org. Chem. 1960, 25, 356.
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