Facile syntheses of anthra[2,3-b] chalcogenophenes

Article abstract of DOI:10.1055/s-0031-1291141

A simple and straightforward method for the synthesis of anthra[2,3-b]furan, anthra[2,3-b]thiophene, and anthra[2,3-b]selenophene from readily available 2-methoxyanthracene is described. Georg Thieme Verlag Stuttgart ? New York.

Full text of DOI:10.1055/s-0031-1291141

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PAPER
paper
Facile Syntheses of Anthra[2,3-b]chalcogenophenes
Kazuki Niimi, Eigo Miyazaki, Itaru Osaka, Kazuo Takimiya*
Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan
Fax +81(82)4245494; E-mail: ktakimi@hiroshima-u.ac.jp
Received: 02.03.2012; Accepted after revision: 17.04.2012
O
Abstract: A simple and straightforward method for the synthesis of
S
anthra[2,3-b]furan, anthra[2,3-b]thiophene, and anthra[2,3-b]seleno-
phene from readily available 2-methoxyanthracene is described.
Key words: anthracene, heteroannulation, oxygen, sulfur, seleni-
um
O
1
S
O
Anthra[2,3-b]thiophene (AT) (Scheme 1), first reported
S
by Castle and co-workers,1 possesses several important
AT
features and can serve as the basic structure of organic
semiconducting materials. The annulated thiophene ring
O
on the anthracene core is planar, which ensures close
2
packing in the solid state facilitating carrier-transport in
electronic devices.2,3 In addition, the vacant thiophene α-
position is highly reactive which enables the introduction
of various substituents, for example, the hexyl derivative
of AT can be employed as a high-performance organic
field-effect transistor with a mobility of 0.85 cm2 V–1 s–1.2b
For these reasons, AT is an attractive target molecule, and
several methods for its synthesis have been developed in-
cluding the use of classical Friedel–Crafts or Grignard ap-
proaches. Lindley and co-workers employed naphthalene-
2,3-dicarboxylic anhydride as a key substrate, which was
reacted with thiophene in the presence of aluminum chlo-
ride or 3-thienylmagnesium bromide to afford 4,11-dihy-
droanthra[2,3-b]thiophene-4,11-dione (1) after treatment
with sulfuric acid. Compound 1 was then reduced to af-
ford AT (Scheme 1).4 Improved syntheses of AT via a
similar anthraquinone intermediate, 5,10-dihydroan-
thra[2,3-b]thiophene-5,10-dione (2) have been reported
independently by two research groups.2,3 The synthesis of
compound 2 was achieved starting from either 2-(trimeth-
ylsilylmethyl)-3-(trimethylammoniummethyl)thiophene
iodide5 or thiophene-2,3-dialdehyde.6 These 2,3-disubsti-
tuted thiophene derivatives are generally less accessible
or are expensive when commercially available. Further-
more, the above-mentioned approaches do not allow easy
access to the analogues anthra[2,3-b]furan (AF) and an-
thra[2,3-b]selenophene (AS). Herein, we report an alter-
native and straightforward approach to sulfur-containing
AT and its furan and selenophene analogues via hetero-
annulation reactions on the anthracene 2,3-bond.
Scheme 1 Conventional syntheses of AT using dihydroanthra[2,3-
b]thiophenediones
2-bromo-3-methoxyanthracene (4),8 which was readily
demethylated using boron tribromide (BBr3) to give 3-
bromoanthracen-2-ol (5) as the key intermediate for the
synthesis of all the anthrachalcogenophenes reported
herein. The bromine and hydroxy functionalities on 5,
however, play different roles in the respective syntheses
of AF, AT and AS.9 For the synthesis of AF, the hydroxy
group was first acetylated to afford compound 6, subse-
quent Sonogashira coupling of which with trimethylsi-
lylacetylene gave 7. Next, base-promoted furan
formation9,10 involving the acetyl and protected o-ethy-
nylphenol functions readily gave anthra[2,3-b]furan (AF)
in 77% isolated yield. On the other hand, for the syntheses
of AT and AS, the hydroxy group of 5 was first converted
into the corresponding triflate 8, which was then utilized
in a Sonogashira coupling with trimethylsilylacetylene to
afford the common precursor 9 for AT and AS. The good
chemoselectivity observed for the Sonogashira coupling
at the triflate over the bromine moiety of 8 was achieved
by using N,N-dimethylformamide as the solvent.11 The fi-
nal ‘thienannulation’ reaction was accomplished in a
straightforward manner using sodium sulfide nonahydrate
(Na2S·9H2O) to give anthra[2,3-b]thiophene (AT) in 84%
isolated yield.11,12 Similarly, the sodium selenide reagent
generated in situ from selenium powder and sodium boro-
hydride gave anthra[2,3-b]selenophene (AS) in a good
84% yield.9,12,13 The three anthra[2,3-b]chalcogenophene
products were characterized by means of spectroscopic
and elemental analyses (see the experimental section).
Scheme 2 shows our new synthetic route to anthra[2,3-
b]chalcogenophenes starting from 2-methoxyanthracene
(3).7 Regioselective bromination at C-3 via lithiation gave
The cyclic voltammograms and absorption spectra of AF,
AT, and AS are shown in Figure 1. These compounds are
isoelectronic with each other and also formally isoelec-
tronic with naphthacene. In fact, they showed similar ox-
SYNTHESIS 2012, 44, 2102–2106
Advanced online publication: 25.05.2012
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DOI: 10.1055/s-0031-1291141; Art ID: SS-2012-F0228-OP
© Georg Thieme Verlag Stuttgart · New York

PAPER
Facile Syntheses of Anthra[2,3-b]chalcogenophenes
2103
1) BuLi
2) BrCH2CH2Br
OMe
OMe
Br
OH
Br
BBr3
quant.
quant.
3
4
5
TMS
H
OAc
Br
Pd(PPh3)2Cl2
CuI
OAc
O
Ac2O
Et3N
Cs2CO3
77%
quant.
quant.
6
TMS
TMS
AF
7
5
TMS
H
Tf2O
Et3N
Pd(PPh3)2Cl2
CuI
OTf
Br
S
Na2S⋅9H2O
quant.
84%
Br
87%
AT
AS
9
8
Se
NaBH4
Se
84%
Scheme 2 Syntheses of AF, AT, and AS
idation behavior with irreversible oxidation waves, and The absorption spectra also reflected the similarities and
their HOMO energy levels can be estimated from the on- differences in the electronic structures of these anthra[2,3-
set voltage (Figure 1a, Table 1). Compared to the HOMO b]chalcogenophenes (Figure 1b). The spectra consisted of
energy level of naphthacene, estimated by the same pro- two major bands in the 250–300 nm and 350–450 nm re-
cedure (5.2 eV below vacuum level), slightly lower-lying gions, which were quite similar to those of naphthacene.
HOMO energy levels for AT and AS (–5.3 eV), and a The low energy bands with vibronic structures assignable
more stabilized HOMO level for AF (–5.4 eV), are esti- to π–π* transitions almost overlapped for AT and AS,
mated (Table 1). This can be explained by the difference whereas AF showed slightly blue-shifted bands (Figure
in aromaticity of the chalcogenophene rings fused on the 1b). This again can be explained due to the lower aroma-
anthracene core. The reduced aromaticity of the furan ticity of furan compared to thiophene and selenophene, in-
lowers the effective conjugation over the molecule, which dicating that the reduced aromaticity of furan also affected
is quite similar to that observed for the naphthodichalco- the LUMO energy level.
genophene series.9,11,14 In fact, the cyclic voltammogram
Although the physicochemical properties of the present
of 2-methoxyanthracene (3) demonstrated onset of oxida-
anthra[2,3-b]chalcogenophene series can be explained by
tion at +1.0 V under identical conditions, which corre-
the different aromaticities of the fused chalcogenophene
sponds to a HOMO energy level of –5.4 eV, implying that
rings, their photoluminescence (PL) behavior required an
the ground state electronic structure of AF can be largely
alternative rationalization (Figure 1c, Table 1). AF
showed an intense emission in solution (φPL = 0.18),
contributed by an oxygen-substituted anthracene-like
structure.14
Figure 1 (a) Cyclic voltammograms; (b) UV/Vis absorption spectra; (c) photoluminescence spectra, of AF, AT, and AS
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 2102–2106

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K. Niimi et al.
PAPER
Table 1 Electronic Properties of AF, AT, and AS
Eoxonset (V)a
EHOMO (eV)b λabsmax (nm)
λabsedge (nm) Eg (eV)c
λPLmax (nm) φPL
Stokes shift (cm–1)e
d
Product
AF
AT
AS
+0.96
+0.88
+0.88
–5.4
–5.3
–5.3
370, 392, 416
388, 410, 436
387, 409, 433
443
466
493
2.80
2.66
2.51
465
488
448
0.18
2510
2450
770
0.063
0.0046
a Vs. Ag/AgCl.
b EHOMO (eV) = –4.4 – Eox
.
onset
c Estimated from λabs
.
edge
d Emission quantum yields were determined by the relative method using 9,10-diphenylanthracene (φem 0.90) as the standard.
e Defined as the difference between the longest λmax in the absorption and the shortest λmax in the emission spectra.
for the 80Se isotope of AS. Elemental analyses were recorded using
a Perkin-Elmer 2400CHN analyzer.
whereas those of AT (φPL = 0.063) and AS (φPL = 0.0046)
were gradually reduced, owing to the so-called heavy
atom effect. Another notable difference in the photolumi-
2-Bromo-3-methoxyanthracene (4)
nescence spectra was that the smallest Stokes shift was
observed for anthra[2,3-b]selenophene (AS). Stokes shifts
are defined as the difference between the longest λmax in
the absorption and the shortest λmax in the emission spec-
tra. These were calculated as follows: 2510 cm–1 for AF,
2450 cm–1 for AT, and 770 cm–1 for AS, respectively. This
trend can be explained qualitatively due to the fact that the
polar excited state can be stabilized more effectively than
the ground state as a result of the higher polarizability of
larger chalcogen atoms. The excited state of anthra[2,3-
b]selenophene (AS), with the most polarizable chalcogen
atom (selenium), is therefore stabilized to the greatest ex-
tent with the least structural influence from the ground
state, thereby resulting in the smallest Stokes shift.
To a soln of 2-methoxyanthracene (3) (40 g, 192 mmol) in THF (1.7
L) was added n-BuLi (236 mL, 384 mmol, 1.63 M soln in hexanes)
at –78 °C, and the mixture stirred for 1 h at r.t. 1,2-Dibromoethane
(35 mL, 400 mmol) was added at –78 °C and the resulting mixture
was stirred for 12 h at r.t. The mixture was poured into sat. aq NH4Cl
soln (200 mL) and extracted with CHCl3 (3 × 50 mL). The com-
bined extracts were washed with brine (3 × 300 mL), dried
(MgSO4), and concentrated in vacuo. The obtained colorless solid
was sufficiently pure for analyses as well as for the next reaction.
Yield: 55.2 g (quant.); colorless solid; mp 163.4–165.3 °C.
1H NMR (400 MHz, CDCl3): δ = 4.04 (s, 3 H), 7.24 (s, 1 H), 7.40–
7.49 (m, 2 H), 7.95 (dd, J = 9.4, 9.0 Hz, 2 H), 8.24 (s, 1 H), 8.27 (s,
2 H).
13C NMR (100 MHz, CDCl3): δ = 56.3, 105.0, 114.8, 124.4, 125.1,
125.4, 127.7, 128.3, 128.6, 130.8, 131.5, 132.3, 132.6, 153.0.
MS (EI): m/z = 286 [M+].
In conclusion, we have successfully developed a straight-
forward method for the synthesis of anthra[2,3-b]chalco-
genophenes (AF, AT and AS) from readily available 2-
methoxyanthracene. The merit of the present synthetic
method is that all three chalcogenophenes are easily pre-
pared from the common intermediate, 3-bromoanthracen-
2-ol (5), which can be readily accessed on large scale (ca.
40 g). We have also elucidated the effects of the different
chalcogen atoms on the electronic structures of the an-
thra[2,3-b]chalcogenophenes. In addition, the simple ac-
cess to these π-extended units makes them potential
building blocks for further elaborated π-functional mate-
rials, and work in this direction is currently under way in
our group.
Anal. Calcd for C15H11BrO: C, 62.74; H, 3.86. Found: C, 62.47; H,
3.69.
3-Bromoanthracen-2-ol (5)
To a soln of 2-bromo-3-methoxyanthracene (4) (39 g, 136 mmol) in
CH2Cl2 (2.0 L) was added dropwise a CH2Cl2 soln of BBr3 (ca. 4 M,
70 mL, 280 mmol) at –78 °C. After stirring for 12 h at r.t., ice (ca.
100 g) was added to the mixture at 0 °C. The resulting mixture was
extracted with CH2Cl2 (3 × 400 mL). The combined organic layer
was washed with brine (3 × 400 mL), dried (MgSO4), and concen-
trated in vacuo. The residue was purified by recrystallization from
hexane to give 3-bromoanthracen-2-ol.
Yield: 37 g (quant.); colorless solid; mp 156 °C (dec.).
IR (KBr): 3525 (OH) cm–1.
1H NMR (400 MHz, CDCl3): δ = 5.68 (s, 1 H), 7.39–7.48 (m, 2 H),
7.57 (s, 1 H), 7.94 (t, J = 8.4 Hz, 2 H), 8.23 (s, 1 H), 8.25 (s, 1 H),
8.29 (s, 1 H).
13C NMR (100 MHz, CDCl3): δ = 109.3, 114.3, 124.5, 125.2, 125.5,
126.1, 127.9, 128.3, 128.7, 131.0, 131.1, 132.7, 148.8.
MS (EI): m/z = 272 [M+].
All reactions were carried out under an N2 atmosphere using anhy-
drous solvents. Column chromatography was carried out using
Wakogel C-200 silica gel (63–210 μm). Melting points were record-
ed using a Yanaco MP-J3 apparatus and are uncorrected. IR spectra
were obtained using a Shimadzu IR Prestige-21 spectrophotometer.
1H and 13C NMR spectra were recorded on a JEOL Lambda 400 or
a Varian 400 MR spectrometer operating at 400 MHz (1H) and 100
MHz (13C). Chemical shifts are reported as δ values (ppm) relative
to tetramethylsilane (TMS) as the internal standard. MS (EI) spectra
were obtained on a Shimadzu QP-2010 spectrometer using an elec-
tron impact ionization procedure (70 eV). The molecular ion peaks
of the selenium-containing products showed typical selenium isoto-
pic patterns, and the selenium-containing mass ion peak is reported
Anal. Calcd for C14H9BrO: C, 61.57; H, 3.32. Found: C, 61.35; H,
3.38.
2-Acetoxy-3-bromoanthracene (6)
To a soln of 3-bromoanthracen-2-ol (5) (11 g, 40 mmol) and Et3N
(17 mL, 120 mmol) in CH2Cl2 (250 mL) was added Ac2O (4.8 mL,
52 mmol) at 0 °C. After stirring for 18 h at r.t., the mixture was di-
luted with HCl (4 M, 100 mL). The resulting mixture was extracted
with CH2Cl2 (3 × 100 mL). The combined organic layer was washed
Synthesis 2012, 44, 2102–2106
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Facile Syntheses of Anthra[2,3-b]chalcogenophenes
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with brine (3 × 200 mL), dried (MgSO4), and concentrated in vacuo
to give practically pure 2-acetoxy-3-bromoanthracene (6).
104 mmol) at 0 °C. After stirring for 18 h at r.t., the mixture was di-
luted with HCl (4 M, 100 mL). The resulting mixture was extracted
with CH2Cl2 (3 × 100 mL). The combined organic layer was washed
with brine (3 × 200 mL), dried (MgSO4), and concentrated in vacuo
to give practically pure 2-bromo-3-(trifluoromethanesulfonyl-
oxy)anthracene (8).
Yield: 13.1 g (quant.); yellow solid; mp 198.0–199.9 °C.
IR (KBr): 1761 (C=O) cm–1.
1H NMR (400 MHz, CDCl3): δ = 2.44 (s, 3 H), 7.47–7.53 (m, 2 H),
7.75 (s, 1 H), 7.98 (dd, J = 8.4, 5.7 Hz, 1 H), 7.99 (dd, J = 8.4, 5.7
Hz, 1 H), 8.30 (s, 1 H), 8.35 (s, 2 H).
13C NMR (100 MHz, CDCl3): δ = 21.0, 115.5, 120.5, 125.6, 126.1,
126.2 (2 C), 128.1, 128.3, 130.4, 130.5, 132.0, 132.2, 132.6, 144.8,
169.2.
Yield: 33.0 g (quant.); yellow solid; mp 115.8–116.8 °C.
IR (KBr): 1433, 1213 (OSO2) cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.52–7.58 (m, 2 H), 7.98 (s, 1 H),
7.99 (dd, J = 8.4, 5.7 Hz, 1 H), 8.01 (dd, J = 8.4, 5.7 Hz, 1 H), 8.34
(s, 1 H), 8.38 (s, 1 H), 8.44 (s, 1 H).
13C NMR (100 MHz, CDCl3): δ = 112.8, 118.8 (q, J = 319 Hz),
120.6, 125.7, 126.8, 126.9, 127.1, 128.1, 128.2, 129.2, 130.3, 132.3,
132.6, 133.8, 143.4.
MS (EI): m/z = 314 [M+].
Anal. Calcd for C16H11BrO2: C, 60.98; H, 3.52. Found: C, 61.24; H,
3.33.
MS (EI): m/z = 404 [M+].
2-Acetoxy-3-[2-(trimethylsilyl)ethyn-1-yl]anthracene (7)
To a degassed soln of 2-acetoxy-3-bromoanthracene (6) (11.3 g, 36
mmol) in Et3N (100 mL) and DMF (100 mL) were added trimethyl-
silylacetylene (6.6 mL, 47 mmol), Pd(PPh3)2Cl2 (1.2 g, 1.8 mmol, 5
mol%) and CuI (665 mg, 3.6 mmol, 10 mol%). After stirring for 11
h at 70 °C, the mixture was diluted with H2O (100 mL) and HCl (4
M, 100 mL). The resulting precipitate was collected by filtration
and washed with H2O. The solid was purified by flash column chro-
matography on silica gel (CHCl3) to give the title compound.
Anal. Calcd for C15H8BrF3O3S: C, 44.46; H, 1.99. Found: C, 44.69;
H, 1.70.
2-Bromo-3-[2-(trimethylsilyl)ethyn-1-yl]anthracene (9)
To a degassed soln of 2-bromo-3-(trifluoromethanesulfonyloxy)an-
thracene (8) (23.9 g, 59 mmol) in Et3N (160 mL) and DMF (160
mL) were added trimethylsilylacetylene (9.1 mL, 60 mmol),
Pd(PPh3)2Cl2 (2.0 g, 3.0 mmol, 5 mol%) and CuI (1.1 mg, 6.0 mmol,
10 mol%). After stirring for 14 h at r.t., the mixture was diluted with
H2O (100 mL) and HCl (4 M, 100 mL). The resulting precipitate
was collected by filtration and washed with H2O. The solid was pu-
rified by flash column chromatography on silica gel (CHCl3) to give
the title compound.
Yield: 11.8 g (quant.); pale-yellow solid; mp 201.7–202.7 °C;
Rf = 1.0 (CHCl3).
IR (KBr): 1767 (C=O) cm–1.
1H NMR (400 MHz, CDCl3): δ = 0.29 (s, 9 H), 2.41 (s, 3 H), 7.45–
7.53 (m, 2 H), 7.66 (s, 1 H), 7.95–8.02 (m, 2 H), 8.23 (s, 1 H), 8.33
(s, 1 H), 8.37 (s, 1 H).
Yield: 18.1 g (87%); pale-yellow solid; mp 175.6–177.5 °C;
Rf = 1.0 (CHCl3).
13C NMR (100 MHz, CDCl3): δ = 0.02, 21.0, 99.7, 100.4, 116.6,
118.9, 125.8, 126.0, 126.4, 126.6, 128.0, 128.4, 129.3, 130.9, 131.9,
132.6, 134.7, 147.3, 169.3.
1H NMR (400 MHz, CDCl3): δ = 0.33 (s, 9 H), 7.47–7.52 (m, 2 H),
7.95–8.05 (m, 2 H), 8.21 (s, 1 H), 8.24 (s, 1 H), 8.28 (s, 1 H), 8.33
(s, 1 H).
13C NMR (100 MHz, CDCl3): δ = 0.00, 99.8, 103.7, 121.0, 121.9,
125.4, 126.2, 126.6 (2 C), 128.3, 128.5, 129.6, 131.0, 131.4, 132.2,
132.7, 134.2.
MS (EI): m/z = 332 [M+].
Anal. Calcd for C21H20O2Si: C, 75.86; H, 6.06. Found: C, 75.61; H,
5.99.
MS (EI): m/z = 352 [M+].
Anthra[2,3-b]furan (AF)
Anal. Calcd for C19H17BrSi: C, 64.59; H, 4.85. Found: C, 64.61; H,
4.82.
To a suspension of Cs2CO3 (25 g, 77 mmol) in N,N-dimethylacet-
amide (2.0 L) and H2O (20 mL) was added 2-acetoxy-3-[2-(trimeth-
ylsilyl)ethyn-1-yl]anthracene (7) (6.0 g, 18 mmol). The mixture was
stirred at 80 °C for 6 h and then poured into sat. aq NH4Cl soln (200
mL). The resulting precipitate was collected by filtration and
washed with H2O. The obtained solid was dissolved in CHCl3 and
purified by flash column chromatography on silica gel (CHCl3) to
give anthra[2,3-b]furan (AF). An analytical sample was obtained by
repetitive gradient sublimation in vacuo (ca. 210 °C at <10–2 Pa un-
der an N2 atm). The mp could not be determined due to ready sub-
limation of the sample at ca. 240 °C, even in a sealed tube.
Anthra[2,3-b]thiophene (AT)
To a suspension of Na2S·9H2O (2.9 g, 6.4 mmol) in NMP (40 mL)
was added 2-bromo-3-[2-(trimethylsilyl)ethyn-1-yl]anthracene (9)
(706 mg, 2.0 mmol), and the mixture stirred at 185–195 °C for 12
h. The mixture was then poured into sat. aq NH4Cl soln (200 mL).
The resulting precipitate was collected by filtration and washed
with H2O. The obtained solid was dissolved in CHCl3 and purified
by flash column chromatography on silica gel (CHCl3) to give an-
thra[2,3-b]thiophene (AT). An analytical sample was obtained by
repetitive gradient sublimation in vacuo (ca. 210 °C at <10–2 Pa un-
der an N2 atm). The mp could not be determined due to ready sub-
limation of the sample at ca. 240 °C, even in a sealed tube.
Yield: 3.0 g (77%); pale-yellow crystals; Rf = 1.0 (CHCl3).
1H NMR (400 MHz, CDCl3): δ = 6.89 (dd, J = 2.4, 1.4 Hz, 1 H),
7.39–7.45 (m, 2 H), 7.73 (d, J = 2.4 Hz, 1 H), 7.97–8.03 (m, 2 H),
8.05 (s, 1 H), 8.23 (s, 1 H), 8.54 (s, 1 H), 8.56 (s, 1 H).
Yield: 610 mg (84%); pale-yellow crystals; Rf = 1.0 (CHCl3).
13C NMR (100 MHz, CDCl3): δ = 105.8, 106.3, 118.9, 124.8, 125.1,
125.8, 126.3, 127.1, 128.2, 129.7, 129.8, 130.4, 130.8, 131.4, 148.2,
148.4.
1H NMR (400 MHz, CDCl3): δ = 7.42 (d, J = 4.3 Hz, 1 H), 7.41–
7.46 (m, 2 H), 7.49 (d, J = 4.3 Hz, 1 H), 8.00–8.04 (m, 2 H), 8.51
(s, 1 H), 8.55 (s, 1 H), 8.59 (s, 1 H), 8.61 (s, 1 H).
13C NMR (100 MHz, CDCl3): δ = 120.6 (2 C), 121.9, 123.5 (2 C),
125.1 (2 C), 125.2, 125.3, 126.6, 128.3 (2 C), 128.8, 129.8, 131.4,
131.7.
MS (EI): m/z = 218 [M+].
Anal. Calcd for C16H10O: C, 88.05; H, 4.62. Found: C, 88.24; H,
4.59.
MS (EI): m/z = 234 [M+].
2-Bromo-3-(trifluoromethanesulfonyloxy)anthracene (8)
To a soln of 3-bromoanthracen-2-ol (5) (22 g, 80 mmol) and Et3N
(34 mL, 240 mmol) in CH2Cl2 (500 mL) was added Tf2O (18 mL,
Anal. Calcd for C16H10S: C, 82.01; H, 4.30. Found: C, 82.09; H,
4.30.
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 2102–2106

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K. Niimi et al.
PAPER
(2) (a) Tang, M. L.; Okamoto, T.; Bao, Z. J. Am. Chem. Soc.
Anthra[2,3-b]selenophene (AS)
To a suspension of Se powder (1.1 g, 14 mmol) in EtOH (20 mL)
was added NaBH4 (513 mg, 13.5 mmol), and the mixture stirred at
r.t. for 1 h. To the resulting mixture was added 2-bromo-3-[2-(tri-
methylsilyl)ethyn-1-yl]anthracene (9) (3.1 g, 9.0 mmol) in NMP
(90 mL), which was then stirred at 185–195 °C for 17 h and poured
into sat. aq NH4Cl soln (200 mL). The resulting precipitate was col-
lected by filtration and washed with H2O. The obtained solid was
dissolved in CHCl3 and purified by flash column chromatography
on silica gel (CHCl3) to give anthra[2,3-b]selenophene (AS). An an-
alytical sample was obtained by repetitive gradient sublimation in
vacuo (ca. 210 °C at <10–2 Pa under an N2 atm). The mp could not
be determined due to ready sublimation of the sample at ca. 240 °C,
even in a sealed tube.
2006, 128, 16002. (b) Tang, M. L.; Reichardt, A. D.;
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Tao, Y.-T. Chem. Mater. 2007, 19, 3018.
(4) Lindley, W. A.; MacDowell, D. W. H.; Petersen, J. L. J. Org.
Chem. 1983, 48, 4419.
(5) Dijkstra, D.; Rodenhuis, N.; Vermeulen, E. S.; Pugsley, T.
A.; Wise, L. D.; Wikstrom, H. V. J. Med. Chem. 2002, 45,
3022.
(6) Laquindanum, J. G.; Katz, H. E.; Lovinger, A. J. J. Am.
Chem. Soc. 1998, 120, 664.
Yield: 2.1 g (84%); pale-yellow crystals; Rf = 1.0 (CHCl3).
(7) Labadie, G. R.; Cravero, R. M. Chem. Educ. 1999, 4, 219.
(8) (a) Niimi, K.; Shinamura, S.; Osaka, I.; Miyazaki, E.;
Takimiya, K. J. Am. Chem. Soc. 2011, 133, 8732. (b) Niimi,
K.; Kang, M. J.; Miyazaki, E.; Osaka, I.; Takimiya, K. Org.
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(9) Nakano, M.; Mori, H.; Shinamura, S.; Takimiya, K. Chem.
Mater. 2012, 24, 190.
(10) (a) Dai, W.-M.; Lai, K. W. Tetrahedron Lett. 2002, 43,
9377. (b) Hayashi, N.; Saito, Y.; Higuchi, H.; Suzuki, K.
J. Phys. Chem. A 2009, 113, 5342.
(11) Shinamura, S.; Osaka, I.; Miyazaki, E.; Nakao, A.;
Yamagishi, M.; Takeya, J.; Takimiya, K. J. Am. Chem. Soc.
2011, 133, 5024.
(12) Kashiki, T.; Shinamura, S.; Kohara, M.; Miyazaki, E.;
Takimiya, K.; Ikeda, M.; Kuwabara, H. Org. Lett. 2009, 11,
2473.
1H NMR (400 MHz, CDCl3): δ = 7.40–7.45 (m, 2 H), 7.61 (d,
J = 6.1 Hz, 1 H), 7.92 (d, J = 6.1 Hz, 1 H), 7.98–8.02 (m, 2 H), 8.46
(s, 1 H), 8.48 (s, 1 H), 8.54 (s, 1 H), 8.56 (s, 1 H).
13C NMR (100 MHz, CDCl3): δ = 123.8, 124.2, 125.0, 125.2, 125.4,
126.7, 127.6, 128.2, 128.3, 128.4, 129.1, 129.5, 129.9, 130.0, 131.5,
131.8.
MS (EI): m/z = 282 [M+].
Anal. Calcd for C16H10Se: C, 68.34; H, 3.58. Found: C, 68.10; H,
3.44.
Acknowledgment
This work was supported financially by Grants-in-Aid for Scientific
Research (No. 23245041) from MEXT, Japan, and a Founding Pro-
gram for World-Leading R&D on Science and Technology
(FIRST), Japan.
(13) Shinamura, S.; Miyazaki, E.; Takimiya, K. J. Org. Chem.
2010, 75, 1228.
(14) Nakano, M.; Shinamura, S.; Houchin, Y.; Osaka, I.;
Miyazaki, E.; Takimiya, K. Chem. Commun. 2012, 48, 5671.
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