General synthesis, structure, and optical properties of benzothiophene-fused benzoheteroles containing Group 15 and 16 elements

Article abstract of DOI:10.1016/j.tet.2016.10.048

A series of benzothieno[3,2-b]benzoheteroles containing Group 15 (N, P, As, and Sb) and Group 16 (O, S, Se, and Te) elements were synthesized by a versatile method. X-ray analyses revealed that all the tetracyclic heteroacene skeletons were planar. A line

Full text of DOI:10.1016/j.tet.2016.10.048

Accepted Manuscript
General synthesis, structure, and optical properties of benzothiophene-fused
benzoheteroles containing Group 15 and 16 elements
Mio Matsumura, Atsuya Muranaka, Rina Kurihara, Misae Kanai, Kengo Yoshida,
Naoki Kakusawa, Daisuke Hashizume, Masanobu Uchiyama, Shuji Yasuike
PII:
S0040-4020(16)31082-1
10.1016/j.tet.2016.10.048
TET 28189
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 23 August 2016
Revised Date: 17 October 2016
Accepted Date: 18 October 2016
Please cite this article as: Matsumura M, Muranaka A, Kurihara R, Kanai M, Yoshida K, Kakusawa
N, Hashizume D, Uchiyama M, Yasuike S, General synthesis, structure, and optical properties of
benzothiophene-fused benzoheteroles containing Group 15 and 16 elements, Tetrahedron (2016), doi:
10.1016/j.tet.2016.10.048.
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ACCEPTED MANUSCRIPT
Graphical Abstract
1

ACCEPTED MANUSCRIPT
General synthesis, structure, and optical properties of benzothiophene-fused benzoheteroles containing
Group 15 and 16 elements
a
b,
c
b
b
Mio Matsumura , Atsuya Muranaka *, Rina Kurihara , Misae Kanai , Kengo Yoshida , Naoki
c
d
b,e
a,
Kakusawa , Daisuke Hashizume , Masanobu Uchiyama , and Shuji Yasuike *
a
School of Pharmaceutical Sciences, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku,
Nagoya 464-8650, Japan
b
Elements Chemistry Laboratory, RIKEN, and Advanced Elements Chemistry Research Team, RIKEN,
Center for Sustainable Resource Science (CSRS), Wako, 351-0198, Japan
c
Faculty of Pharmaceutical Sciences, Hokuriku University, Ho-3 Kanagawa-machi, Kanazawa
9
20-1181, Japan
d
Materials Characterization Support Unit, RIKEN Center for Emergent Matter Science (CEMS),
Wako 351-0198, Japan
e
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
*
Corresponding authors. Tel.: +81 48 467 2857; fax: +81 48 467 2879 (A. M.); tel.: +81 52 757 6775;
fax: +81 52 757 6799 (S. Y.); e-mail addresses: atsuya-muranaka@riken.jp (A. Muranaka),
2

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s-yasuik@dpc.agu.ac.jp (S. Yasuike).
3

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ABSTRACT: A series of benzothieno[3,2-b]benzoheteroles containing Group 15 (N, P, As, and Sb) and
Group 16 (O, S, Se, and Te) elements were synthesized by a versatile method. X-ray analyses revealed
that all the tetracyclic heteroacene skeletons were planar. A linear relationship was found between the
excitation energies of Group 16-heteroacenes and their atomic radius, in contrast to Group
1
5-heteroacenes. Density functional theory calculations and electrochemical measurements were
performed to understand the structure-optical property relationship.
Keywords
Benzothieno[3,2-b]benzoheterole
Tetracyclic heteroacene
Group 15 and 16 elements
Comprehensive synthesis
Molecular structure
DFT calculation
4

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1
. Introduction
Linearly fused heteroacenes are attracting increasing interest owing to their intriguing potential for
1
application in organic semiconductors for organic field-effect transistors (OFETs). Among them,
benzothieno[3,2-b]benzothiophene and its derivatives (I) have been widely investigated, leading to the
1
c,e,2
development of high-performance organic semiconductors.
In connection with these studies, the
3
3d,4
benzothiophene-fused benzoheteroles (II), such as nitrogen (M = N-R’), phosphorus (M = P-R’),
5
1c,e,2c,6
oxygen (M = O), and selenium (M = Se)
derivatives, have been sporadically prepared to develop
synthetic routes and investigate their fundamental, electrochemical, and electronic device properties (Fig.
). However, to the best of our knowledge, comprehensive synthesis of these heteroacenes has never
1
been carried out. We have been extensively working on the development of novel synthetic
methodologies for a library of heterocycles containing Group 15 (N, P, As, and Sb) and Group 16 (O, S,
Se, and Te) elements, and have already reported the synthesis and physical properties of
7
1
-benzo[b]heteroles containing a series of Group 15 and 16 elements. In these articles, replacement of
the Group 16 heteroatom leads to a considerable spectral shift, depending on the size of the heteroatom.
8
Here, we report a convergent synthesis of benzothiophene-fused tetracyclic heteroacenes and a detailed
comparison of the molecular structures and optical properties of the obtained heteroacenes. For the
Group 15-heteroacenes, 10-phenyl derivatives were targeted because of the stability and handling ability.
5

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Fig. 1. Benzothiophene-fused tetracyclic heteroacenes.
2
. Results and discussion
The established convergent synthetic routes to benzothiophene-fused benzoheteroles 3 are shown in
2 2
Scheme 1. The key precursors 2a and 2b were synthesized by I - and Br -mediated electrophilic
9
cyclization of simple diphenyl acetylenes 1a and 1b, respectively. When 1a was reacted with Br
2
, the
desired 2-halophenyl benzofulan derivative was not obtained but the triple bond underwent bromine
addition to form a 1,2-dibromoalkene. Compound 2 was treated with n- or t-BuLi in anhydrous diethyl
ether under an argon atmosphere, followed by trapping of the dilithio intermediate with an electrophilic
reagent, which resulted in ring closure to afford a range of the desired benzothiophene-fused
benzoheteroles (3b-h) in moderate yields. Indole derivative 3a was synthesized by the reaction of 2b
1
0
and aniline in the presence of Pd
2
(dba)
3
and tri-tert-butylphosphonium tetrafluoroborate at 125 °C.
6

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Scheme 1. Synthesis of benzothiophene-fused benzoheteroles.
2 3 3 4
For 3a; method A. aniline (0.5 mmol), 2b (0.55 mmol), Pd (dba) (22 mol%), P(t-Bu) HBF (22
mol%), t-BuONa (1.7 mmol), and toluene (5 mL) at 125 °C. For 3b-d and f-h; method B. 2b (2.0 mmol),
n-BuLi (2.4 eq.), Group 15 or 16 reagent (4 mmol), and diethyl ether (40 mL), at -20 °C to rt. For 3e;
2 2
method B. 2a (2.0 mmol), t-BuLi (4 eq.), (PhSO ) S (4 mmol), and diethyl ether (30 mL), at -78 °C to rt.
We successfully obtained single crystals of all the heteroacenes and then carried out X-ray
2
e,11
analysis.
Selected bond lengths and angles are summarized in the Supporting Information, and the
ORTEP drawings are provided in Fig. 2. Fig. 2 clearly shows that the tetracyclic skeletons are planar. As
expected, with the increase in the size of the heteroatom, the carbon-heteroatom bond lengths (M-C2 and
M-C3) increase, and the C2-M-C3 bond angles decrease. The P, As, and Sb atoms in the Group
1
5-heteroacenes were tetrahedrally coordinated. This is in contrast to the planar coordination of the N
7

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atom in 3a, in which the bond angles are close to 120° [C2-N-C(Ph): 123.6(2)°; C3-N-C(Ph): 128.2(2)°].
The bond lengths and angles in 3b and 3c were essentially the same as those in 1-phenylphosphindole
and 1-phenylarsindole, except for the C3-C4 bond length. The C3-C4 bond lengths in 3b (1.3718(14) Å)
and 3c (1.362(3) Å) are considerably longer than the corresponding C-C bond lengths in
1
2
7b
1
-phenylphosphindole (1.326(4) Å) and 1-phenylarsindole (1.330(3) Å) , respectively, which implies
that benzothiophene-fusion significantly affects the C3-C4 bond properties in the present system.
A herringbone arrangement was observed in the assembly of benzothieno[2,3-b]benzothiophene (3f),
1
3
which is considered to be responsible for its excellent charge transport properties. The packing
structure of the benzoselenophene derivative (3g) was found to be very similar to that of 3f (see the
Supporting Information), whereas the benzofuran (3e) and benzotellurophene (3h) derivatives adopted
different packing structures. This difference may be attributed to the atomic radius of the chalcogens.
The difference in the sizes of the Se (1.16 Å) and S (1.02 Å) atoms is not as much as that between the
1
4
sizes of O (0.73 Å) and Te (1.36 Å). In the case of Group 15-heteroacenes, no herringbone motif was
observed, probably due to the presence of a peripheral phenyl group. The packing geometry of the
arsindole derivative (3c) was very close to that of the phosphindole derivative (3b), which may also be
1
4
correlated with the atomic radius.
8

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Fig. 2. Top views (top) and side views (bottom) of 3 in the solid state (50% probability level); the
disordered atoms and hydrogen atoms are omitted for clarity. One of two geometries in the unit cell was
drawn for 3d.
The photophysical properties of the present benzothiophene-fused benzoheteroles were evaluated
using ultraviolet (UV) absorption spectroscopy; the spectra are shown in Fig. 3, and the photophysical
data are summarized in Table 1. The λmax of Group 16-heteroacenes 3e-h was systematically shifted
9

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toward the red region (by ca. 10 nm) on going from O to Te, while the Group 15-heteroacenes did not
exhibit such a spectral shift. These spectral changes are very similar to those of the non-fused
7
b
benzoheteroles. The red shift of the Group 16-heteroacenes suggests that the conjugated system is
extended by the heteroatoms. Interestingly, a linear relationship was found between the excitation
14
energies for the lowest-energy transition of the Group 16-heteroacenes (3e-h) and their atomic radius
(
Fig. 4). Such a linear relationship was also observed for heteroles, benzoheteroles, and other related
heterocyclic systems. Judging from the slopes of the least square lines, the effect of the chalcogen atom
on the spectral red-shift decreases with the fusion of benzene and benzothiophene.
1
5
To further understand the red-shift observed for the Group 16-heteroacenes, DFT calculations and
electrochemical measurements were performed (Table 1 and Fig. 5). Geometry optimization calculations
were carried out for all the heteroacenes at the B3LYP/6-311G* (SDD for As, Sb, Se, and Te) level of
theory, and the accuracy of the optimized structures were assessed by comparison with the X-ray
analysis-derived structures. As shown in the Supporting Information, all the HOMOs and LUMOs are
derived from
energy gap (
π
orbitals of the tetracyclic heteroacene skeletons. It is evident that the HOMO-LUMO
ꢀ
EHL) decreases as the size of the chalcogen atom increases. The decrease in EHL was not
ꢀ
seen in the Group 15-heteroacenes. These results correlate well with the optical properties observed for
the heteroacenes. The destabilization of the HOMO energy for the Group 16-heteroacenes with the
larger chalcogen atom was experimentally confirmed by measuring the first oxidation potentials (Epa).
1
0

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+
The largest potential difference (0.74 V vs Fc/Fc ) was observed between the E values of the
pa
benzofuran derivative (1.17 V) and benzotellurophene derivative (0.43 V).
Fig. 3. UV absorption spectra of the Group 15- (a) and 16-heteroacenes (b) in MeOH.
Table 1. Photophysical data and calculated HOMO and LUMO levels of 3.
-3
λmax
10
ε
EHOMO ELUMO ꢀEHL
M
a
-1
-1 a
b
b
c
(
nm) (M cm )
(eV)
(eV) (eV)
3
3
a
NPh 342
PPh 340
8.2
9.5
11
-5.36 -1.19 4.17
-5.77 -1.60 4.17
-5.78 -1.60 4.18
-5.77 -1.62 4.15
-5.78 -1.43 4.35
-5.79 -1.50 4.28
-5.77 -1.54 4.22
-5.67 -1.55 4.12
b
3
c
AsPh 339
SbPh 344
3
d
9.6
24
3
e
O
S
318
329
335
349
3
f
10
3
3
g
Se
Te
10
h
7.2
11

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a
b
From absorption spectra in MeOH. DFT calculation at
the level of B3LYP/6-311G* (SDD for As, Se, Sb and Te).
c
Computed HOMO-LUMO gap.
1
4
-1
Fig. 4. Plots of atomic radius (Å) vs experimental excitation energy (cm ) for the lowest-energy
transition for a series of the Group 16-heteroacenes. The excitation energies were based on the λmax
values of Table 1. The straight line was drawn using the least-squares method. The excitation energies
for heteroles and benzoheteroles were taken from references 16 and 7b.
1
2

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Fig. 5. Calculated HOMO and LUMO energy levels for the Group 16-heteroacenes (left) and the
+
contour plots of the HOMO and the first oxidation potentials E / (V vs Fc/Fc ) (right). The calculations
pa
were performed at the level of B3LYP/6-311G* (SDD for Se and Te).
3
. Conclusion
In conclusion, we demonstrated a novel divergent synthesis of a series of benzothiophene-fused
benzoheteroles containing Group 15 and 16 elements from one common precursor,
3
-bromo-2-(2-bromophenyl)benzo[b]thiophene (2b), and performed the first systematic comparison of
these structures and properties. X-ray single crystal structural analysis showed that the tetracyclic
heteroacene skeletons are planar and that the P, As, and Sb atoms are tetrahedrally coordinated. We
clarified that the size of the heteroatom incorporated in the heteroacene skeletons strongly affects the
packing structures and physicochemical properties. As heavier heteroatoms were introduced, the Group
1
3

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1
6-heteroacenes systematically displayed greater red-shift and higher HOMO energy levels. We believe
that such polycyclic heteroacenes offer a new perspective for the design of new types of functional
π
4
4
-electron materials for organic electronics applications.
. Experimental section
.1. General procedures
Melting points were taken on a Yanagimoto micro melting point hot-stage apparatus (MP-S3) and are
1
13
not corrected. H NMR (TMS:
δ
: 0.00 as an internal standard) and C NMR (CDCl :
δ: 77.00 as an
3
internal standard) spectra were recorded on a JEOL JNM-AL400 or JNM-PMX60 (400 MHz and 100
SI
MHz) spectrometer in CDCl unless otherwise stated. Mass spectra (MS) were obtained on a JEOL
3
JMS-SX-102A instrument. Elemental analyses were performed on MT-5 elemental analyzer
(Yanagimoto). IR spectra were recorded on a FT-720 system from HORIBA spectrometer and are
-1
reported in frequency of absorption (cm ). Only selected IR peaks are reported. All manipulations
involving air- and/or moisture-sensitive compounds were carried out with the standard Schlenk
technique under an argon atmosphere. All chromatographic separations were accomplished with Silica
Gel 60N (Kanto Chemical Co., Inc.). Thin-layer chromatography (TLC) was performed with
Macherey-Nagel Pre-coated TLC plates Sil G25 UV . Most of reagents were used without further
2
54
purification unless otherwise specified. Benzo[b]furan 2a was prepared according to the reported
8
, 17
procedures.
1
4

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4
4
1
.2. Experimental procedures and data of synthetic intermediates
.2.1.
1-Bromo-2-[(2-methylthiophenyl)ethynyl]benzene
(1b).
To
a
solution
of
-iodo-2-(methylthio)benzene (19.4 g, 77.4 mmol, 1.2 eq.) in diethylamine (130 mL), PdCl (PPh ) (445
2
3 2
mg, 0.63 mmol, 1.0 mol%), CuI (499 mg, 2.6 mmol, 4.1 mol%) and 2-bromophenyl acetylene (11.5 g,
3.5 mmol) were added at 0 °C, and stirred for 15 min. The reaction mixture was stirred for 15 h at room
temperature, concentrated under reduced pressure. The residue was dissolved in CH Cl (300 mL) and
6
2
2
H O (200 mL). The mixture was filtered over Celite and extracted with CH Cl (200 mL × 2). The
2
2
2
combined extracts were dried over anhydrous magnesium sulfate, filtered, and concentrated under
reduced pressure. The residue was purified by column chromatography using hexane/CH Cl (5:1) as
2
2
1
eluent to give 1b as pale yellow prisms (16.4 g, 85% yield): mp 61-63 °C (from hexane/CH Cl ); H
2
2
NMR (CDCl , 400 MHz) δ 7.61 (d, J = 7.8 Hz, 2H), 7.54 (d, J = 6.9 Hz, 1H), 3.34-7.27 (m, 2H), 7.19 (d,
3
1
3
J = 7.8 Hz, 2H), 7.12 (t, J = 7.3 Hz, 1H), 2.52 (s, 3H); C NMR (CDCl , 100 MHz)
δ
141.9 (C), 133.5
3
(CH), 132.7 (CH), 132.5 (CH), 129.5 (CH), 129.1 (CH), 127.0 (CH), 125.4 (C), 125.3 (C), 124.3 (CH),
-1
1
24.2 (CH), 121 (C), 94.1 (C), 91.3 (C), 15.2 (CH ); IR (KBr):
ν
2216 (C
≡
C) cm ; HRMS-EI (m/z):
3
+
calcd for C H BrS [M] 301.9765, found 301.9774; Anal. Calcd for C H BrS: C, 59.42; H, 3.66,
1
5
11
15 11
found: C, 59.58; H, 3.79.
.2.2. 3-Bromo-2-(2-bromophenyl)benzo[b]thiophene (2b). A solution of bromine (5.0 g, 31.3 mmol) in
CH Cl (20 mL) was added dropwise to a solution of 1b (4.70 g, 15.5 mmol) in CH Cl (40 mL) for 45
4
2
2
2
2
1
5

ACCEPTED MANUSCRIPT
min at 0 °C and stirred for 30 min. After stirred for 1 h at room temperature, to the reaction mixture was
added CH Cl (150 mL) and saturated sodium thiosulfate (200 mL) at 0 °C, and filtrated over Celite. The
2
2
filtrate was extracted with CH Cl (150 mL × 2). The combined organic layer was dried over anhydrous
2
2
magnesium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by
column chromatography using hexane/CH Cl (20:1) as eluent to give 2b as colorless prisms (5.29 g,
2
2
1
9
7
2% yield): mp 75-79 °C (from hexane/CH Cl ); H NMR (CDCl , 400 MHz) δ 7.84 (d, J = 7.8 Hz, 1H),
2 2 3
1
3
.83 (d, J = 7.8 Hz, 1H), 7.71 (d, J = 7.8 Hz, 1H), 7.52-7.39 (m, 4H), 7.33 (t, J = 7.8 Hz, 1H); C NMR
(
CDCl , 100 MHz)
δ
138.4 (C), 137.9 (C), 137.3 (C), 134.1 (C), 133.0 (CH), 132.5 (CH), 130.7 (CH),
3
1
27.2 (CH), 125.7 (CH), 125.2 (CH), 124.6 (C), 123.6 (CH), 122.3 (CH), 108.6 (C); HRMS-EI (m/z):
+
calcd for C H Br S [M] 365.8713, found 365.8679; Anal. Calcd for C H Br S: C, 45.68; H, 2.19,
1
4
8
2
14
8
2
1
8
found C, 45.13; H, 2.33. Spectroscopic data are in accordance with the literature.
4
.3. Experimental procedures and data of 10-phenyl[1]benzothieno[3,2- ]indole (3a)
b
The mixture of aniline (47 mg, 0.51 mmol), 2b (203 mg, 0.55 mmol), tri-tert-butylphosphonium
tetrafluoroborate (33 mg, 0.11 mmol, 22 mol%), sodium tert-butoxide (160 mg, 1.67 mmol), and
tris(dibenzylideneacetone)dipalladium (101 mg, 0.11 mmol, 22 mol%) in toluene (5 mL) was stirred for
3
0 min at room temperature. The sealed reaction tube was then heated to 125 °C for 24 h. The mixture
was cooled to room temperature, diluted with CH Cl and water at 0 °C, and filtered over Celite. The
2
2
filtrate was extracted with CH Cl . The combined organic layer was washed with brine, dried over
2
2
1
6

ACCEPTED MANUSCRIPT
anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure. The residue was
purified by column chromatography using hexane/CH Cl (20:1) as eluent to give 3a as yellow prisms
2
2
1
(
107 mg, 71% yield): mp 111-114 °C (from ethanol/CH Cl ); H NMR (CDCl , 400 MHz)
δ
7.88 (d, J =
2
2
3
8
.2 Hz, 1H), 7.82 (d, J = 7.8 Hz, 1H), 7.64-7.52 (m, 5H), 7.36 (d, J = 8.2 Hz, 1H), 7.30-7.17 (m, 5H);
1
3
C NMR (CDCl , 100 MHz)
δ 143.1 (C), 142.5 (C), 137.9 (C), 137.5 (C), 129.7 (CH), 128.2 (CH),
3
1
27.7 (CH), 126.8 (C), 124.3 (CH), 124.0 (CH), 123.9 (CH), 123.4 (CH), 122.1 (C), 120.5 (CH), 120.4
+
(
CH), 119.3 (CH), 116.8 (C), 111.0 (CH); HRMS-EI (m/z): calcd for C H NS [M] 299.0769, found
2
0
13
2
99.0769; Anal. Calcd for C H NS: C, 80.23; H, 4.38; N, 4.68, found C, 80.27; H, 4.72; N, 4.70.
20 13
3
d
Spectroscopic data are in accordance with the literature.
.4. General procedure of [1]benzothieno[3,2- ][1]benzoheteroles (3b-h)
A solution of BuLi was added dropwise to a solution of 2 (2.0 mmol) in diethyl ether 40 mL at -20 °C
for 3b-d, f-h) or -78 °C (for 3e) and stirred. After 15 min, to the reaction mixture Group 15 or 16
4
b
(
reagent (4 mmol) was added and the resulting mixture was gradually raised to room temperature and
stirred for 15 h. The reaction mixture was diluted with CH Cl (100 mL) and water (100 mL), and
2
2
filtrated over Celite. The filtrate was extracted with CH Cl (100 mL × 2). The combined organic layer
2
2
was washed with brine (200 mL × 2), dried over anhydrous magnesium sulfate, filtered, and
concentrated under reduced pressure. The residue was purified by column chromatography using
hexane/CH Cl .
2
2
1
7

ACCEPTED MANUSCRIPT
4
2
4
.4.1. 10-Phenyl[1]phosphindolo[3,2-b][1]benzothiophene (3b). Following the general procedure, with
b, a solution of 1.75 M n-BuLi in hexane (3.1 mL, 4.8 mmol), and dichlorophenylphosphine (718 mg,
.0 mmol) afforded compound 3b as colorless prisms (430 mg, 68% yield); mp 133-137 °C (from
1
methanol/CH Cl ); H NMR (CDCl , 400 MHz)
δ
7.89 (d, J = 8.2 Hz, 1H), 7.73-7.67 (m, 3H), 7.45-7.22
2
2
3
1
3
(
m, 9H); C NMR (CDCl , 100 MHz)
δ
148.3 (C, d, J = 3.8 Hz), 146.0 (C, d, J = 4.8 Hz), 143.0 (C,
3
c,p
c,p
d, J = 4.8 Hz), 139.6 (C, d, J = 1.9 Hz), 138.1 (C, d, J = 6.7 Hz), 138.1 (C, d, J = 17.3 Hz), 133.9
c,p
c,p
c,p
c,p
(
C, d, Jc,p = 17.3 Hz), 132.8 (CH, d, Jc,p = 21.1 Hz), 130.2 (CH, d, Jc,p = 21.1 Hz), 129.5 (CH), 128.8
CH, d, J = 7.7 Hz), 128.7 (CH, d, J = 8.6 Hz), 126.8 (CH, d, J = 8.6 Hz), 125.0 (CH), 124.5 (CH),
(
c,p
c,p
c,p
+
1
3
23.6 (CH), 123.0 (CH), 121.7 (CH); HRMS-EI (m/z): calcd for C H PS [M] 316.0476, found
20 13
16.0473; Anal. Calcd for C H PS: C, 75.93; H, 4.14, found C, 75.57; H, 4.36. Spectroscopic data are
2
0
13
4
b
in accordance with the literature.
4
.4.2. 10-Phenyl[1]benzoarsolo[3,2-b][1]benzothiophene (3c). Following the general procedure, with
b, a solution of 1.75 M n-BuLi in hexane (3.1 mL, 4.8 mmol), and dichlorophenylarsine (890 mg, 4.0
2
mmol) afforded compound 3c as colorless prisms (562 mg, 78% yield); mp 118-120 °C (from
1
methanol/CH Cl ); H NMR (CDCl , 400 MHz)
δ 7.89 (d, J = 7.3 Hz, 1H), 7.75 (d, J = 6.9 Hz, 1H),
2
2
3
1
3
7
1
1
.68 (t, J = 7.8 Hz, 2H), 7.42 (t, J = 6.9 Hz, 1H), 7.34-7.16 (m, 8H); C NMR (CDCl , 100 MHz) δ
3
49.9 (C), 148.2 (C), 142.4 (C), 141.4 (C), 140.7 (C), 139.5 (C), 138.3 (C), 132.3 (CH), 131.3 (CH),
28.9 (CH), 128.8 (CH), 127.1 (CH), 125.0 (CH), 124.4 (CH), 123.4 (CH), 123.4 (CH), 122.5 (CH);
1
8

ACCEPTED MANUSCRIPT
+
HRMS-EI (m/z): calcd for C H AsS [M] 359.9954, found 359.9948; Anal. Calcd for C H AsS: C,
2
0
13
20 13
6
4
2
6.67; H, 3.64, found C, 66.44; H, 3.80.
.4.3. 10-Phenyl[1]benzostibolo[3,2-b][1]benzothiophene (3d). Following the general procedure, with
b, a solution of 1.75 M n-BuLi in hexane (3.1 mL, 4.8 mmol), and dibromophenylstibane (1.43 g, 4.0
mmol) afforded compound 3d as colorless prisms (585 mg, 72% yield); mp 100-102 °C (from
1
hexane/CH Cl ); H NMR (CDCl , 400 MHz)
δ 7.89 (d, J = 6.9 Hz, 1H), 7.74 (d, J = 7.3 Hz, 1H), 7.69
2
2
3
1
3
(
(
(
(
d, J = 7.8 Hz, 1H), 7.68 (d, J = 6.9 Hz, 1H), 7.43-7.14 (m, 9H); C NMR (CDCl , 100 MHz) δ 156.1
3
C), 145.4 (C), 145.4 (C), 142.6 (C), 141.4 (C), 139.4 (C), 137.4 (C), 135.3 (CH), 134.8 (CH), 129.1
CH), 128.9 (CH), 128.8 (CH), 127.4 (CH), 124.9 (CH), 124.4 (CH), 124.3 (CH), 123.7 (CH), 123.0
+
CH); HRMS-EI (m/z): calcd for C H SbS [M] 405.9776, found 405.9770; Anal. Calcd for
2
0
13
C H SbS: C, 59.00; H, 3.22, found C, 58.87; H, 3.37.
20
13
4
.4.4. [1]Benzothieno[3,2-b][1]benzofuran (3e). Following the general procedure, with 2a, a solution of
1
.05 M t-BuLi in hexane (7.6 mL, 8.0 mmol), and bis(phenylsulfonyl)sulfide (1.25 g, 4 mmol) afforded
1
compound 3e as colorless prisms (245 mg, 55% yield): mp 132-134 °C (from hexane/CH Cl ); H NMR
2
2
(
CDCl , 400 MHz) δ 7.99 (d, J = 7.8 Hz, 1H), 7.86 (d, J = 8.2 Hz, 1H), 7.71 (d, J = 7.8 Hz, 1H), 7.63 (d,
3
1
3
J = 7.8 Hz, 1H), 7.46 (t, J = 7.8 Hz, 1H), 7.37 (t, J = 7.8 Hz, 2H), 7.33 (t, J = 8.2 Hz, 1H); C NMR
CDCl , 100 MHz) 158.8 (C), 153.0 (C), 142.0 (C), 125.1 (C), 124.9 (CH), 124.9 (CH), 124.3 (CH),
24.0 (C), 123.3 (CH), 119.7 (CH), 119.6 (CH), 118.6 (C), 112.5 (CH); HRMS-EI (m/z): calcd for
(
δ
3
1
1
9

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+
C H OS [M] 224.0296, found 224.0297; Anal. Calcd for C H OS: C, 74.97; H, 3.60, found C, 74.99;
14
8
14
8
3
d
H, 3.65. Spectroscopic data are in accordance with the literature.
4
.4.5. [1]Benzothieno[3,2-b][1]benzothiophene (3f). Following the general procedure, with 2b, a
solution of 1.75 M n-BuLi in hexane (3.1 mL, 4.8 mmol), and bis(phenylsulfonyl)sulfide (1.25 g, 4.0
mmol) afforded compound 3f as colorless prisms (312 mg, 65% yield); mp 215-219 °C (from
1
hexane/CH Cl ); H NMR (CDCl , 400 MHz)
δ 7.91 (d, J = 8.0 Hz, 2H), 7.88 (d, J = 8.0 Hz, 2H), 7.45
2
2
3
1
3
(
t, J = 8.0 Hz, 2H), 7.39 (t, J = 8.0 Hz, 2H); C NMR (CDCl , 100 MHz)
δ
142.2 (C), 133.4 (C), 133.1
3
+
(
C), 125.0 (CH), 124.9 (CH), 124.0 (CH), 121.6 (CH); HRMS-EI (m/z): calcd for C H S [M]
14 8 2
2
40.0067, found 240.0067; Anal. Calcd for C H S : C, 69.96; H, 3.36, found C, 70.04; H, 3.64.
14 8 2
2
c
Spectroscopic data are in accordance with the literature.
4
.4.6. [1]Benzoselenolo[3,2-b][1]benzothiophene (3g). Following the general procedure, with 2b, a
solution of 1.75 M n-BuLi in hexane (3.1 mL, 4.8 mmol), and bis(phenylsulfonyl)selenide (1.44 g, 4.0
mmol) afforded compound 3g as red prisms (379 mg, 66% yield); mp 206-209 °C (from
1
ethanol/CH Cl ); H NMR (CDCl , 400 MHz)
δ 7.94 (d, J = 7.8 Hz, 1H), 7.91 (d, J = 7.8 Hz, 1H), 7.86
2
2
3
(d, J = 7.8 Hz, 1H), 7.80 (d, J = 7.3 Hz, 1H), 7.44 (t, J = 7.8 Hz, 1H), 7.43 (t, J = 7.8 Hz, 1H), 7.38 (t, J
1
3
=
7.8 Hz, 1H), 7.32 (t, J = 7.3 Hz, 1H); C NMR (CDCl , 100 MHz) δ 142.1 (C), 141.2 (C), 135.7 (C),
3
1
35.6 (C), 135.2 (C), 131.7 (C), 127.0 (CH), 125.3 (CH), 125.2 (CH), 124.9 (CH), 124.9 (CH), 123.8
+
(
CH), 123.1 (CH), 122.2 (CH); HRMS-EI (m/z): calcd for C H SSe [M] 287.9512, found 287.9505;
1
4
8
2
0

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Anal. Calcd for C H SSe: C, 58.54; H, 2.81, found C, 58.71; H, 3.08. Spectroscopic data are in
1
4
8
2
c
accordance with the literature.
4
.4.7. [1]Benzotellurolo[3,2-b][1]benzothiophene (3h). Following the general procedure, with 2b, a
solution of 1.75 M n-BuLi in hexane (3.1 mL, 4.8 mmol), and tellurium powder (522 mg, 4.0 mmol)
afforded compound 3h as pale yellow needles (343 mg, 51% yield); mp 164-166 °C (from
1
methanol/CH Cl ); H NMR (CDCl , 400 MHz)
δ 7.95 (d, J = 7.8 Hz, 1H), 7.91 (d, J = 7.3 Hz, 1H),
2
2
3
7
.88 (d, J = 8.7 Hz, 1H), 7.66 (d, J = 8.7 Hz, 1H), 7.44 (t, J = 7.3 Hz, 1H), 7.40-7.36 (m, 2H), 7.19 (t, J
1
3
=
7.3 Hz, 1H); C NMR (CDCl , 100 MHz) δ 141.8 (C), 140.1 (C), 139.9 (C), 139.6 (C), 133.1 (CH),
3
1
30.9 (C), 126.1 (CH), 125.3 (CH), 125.1 (CH), 124.9 (CH), 123.5 (CH), 123.4 (CH), 119.2 (C);
+
HRMS-EI (m/z): calcd for C H STe [M] 337.9407, found 337.9419; Anal. Calcd for C H STe: C,
14
8
14
8
5
0.06; H, 2.40, found C, 50.08; H, 2.58.
4
.5. Cyclic voltammograms
Electrochemical measurements were conducted on a HZ-3000 voltammetric analyzer (Hokuto Denko)
under argon atmosphere in a CH Cl solution of tetrabutylammonium perchlorate (0.1 M). A glassy
2
2
carbon electrode was used as a working electrode, a platinum-wire was used as the counter electrode,
and an Ag/AgCl electrode was used as the reference electrode. The CV curves were calibrated using the
+
ferrocene/ferrocenium (Fc/Fc ) redox couple as an external standard which was measured under the
same conditions after the measurement of samples.
2
1

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4
.6. X-ray crystallographic data
The X-ray diffraction measurements of compounds 3 were carried out using a Rigaku AFC-8 with
Saturn70 CCD using Mo K radiation ( = 0.71073 Å). The CrystalClear program was used for
absorption correction. The structure was solved by direct methods using SIR2004 (for 3a-f, h) or
α
λ
1
9
SHELXL-97 (for 3g), followed by successive refinements using the full-matrix least-squares method
2
20
on F using SHELXL-97. All the nonhydrogen atoms were refined anisotropically, whereas the
hydrogen atoms were refined isotropically.
The experimental and refinement details of the X-ray crystallographic structures of compound can be
obtained free of charge from the Cambridge Crystallographic Data Centre (http://www.ccdc.cam.ac.uk),
CCDC #1481568 to 1481575 for 3a-3h, respectively.
4
.7. Computational details
All calculations were performed at the DFT level, by means of the B3LYP functional as implemented in
1
5
Gaussian 09. The 6-311G* basis sets were used for H, C, N, O, P, and S atoms, while the SDD basis
sets were applied for As, Se, Sb, and Te atoms. X-ray structures of 3a-3h were used as initial structures
for geometry optimization calculations. Vibrational frequency computations verified the nature of the
stationary points.
Acknowledgements
This research was partly supported by grants (to M. U.) from JSPS KAKENHI (S) (No. 24229011),
2
2

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Uehara Memorial Foundation, Asahi Glass Foundation, and Nagase Science Technology Development
Foundation. Partial financial support for this work was provided by research grants (to S. Y.) from
Hokuriku University and Institute of Pharmaceutical Life Sciences, Aichi Gakuin University. The
calculations were performed on the RIKEN Integrated Cluster of Clusters (RICC) and HOKUSAI
GreatWave. We gratefully acknowledge the Advanced Center for Computing and Communication,
RIKEN for providing computational resources.
Supplementary data
Supplementary data associated with this article can be found in the online version, at XXX
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