Derivatization of Tetrafluorobenzo[c]Thiophene. Preparation of Tetrafluorothiabenzoporphyrin

Article abstract of DOI:10.3987/COM-07-S(U)46

The Diels-Alder reactions of tetrafluorobenzo[c]thiophene with electron-deficient olefins such p-benzoquinone and bis(phenylsulfonyl)ethylene gave adducts in moderate yields, while no product was obtained in the reaction with butyl vinyl ether. The Vilsme

Full text of DOI:10.3987/COM-07-S(U)46

HETEROCYCLES, Vol. 73, 2007
673
HETEROCYCLES, Vol. 73, 2007, pp. 673 - 688. © The Japan Institute of Heterocyclic Chemistry
Received, 30th June, 2007, Accepted, 10th August, 2007, Published online, 17th August, 2007. COM-07-S(U)46
DERIVATIZATION OF TETRAFLUOROBENZO[c]THIOPHENE.
PREPARATION OF TETRAFLUOROTHIABENZOPORPHYRIN
Hiroki Uoyama,a,b Keisuke Nakamura,a Marie Tukiji,a,b Mina Furukawa,a
and Hidemitsu Unoa,b*
a
Division of Synthesis and Analysis, Department of Molecular Science,
b
Integrated Center for Sciences, Ehime University, Matsuyama 790-8577.
CREST, Japan Science and Technology Agency (JST), Matsuyama 790-8577,
Japan, uno@dpc.ehime-u.ac.jp
Abstract – The Diels-Alder reactions of tetrafluorobenzo[c]thiophene with
electron-deficient olefins such p-benzoquinone and bis(phenylsulfonyl)ethylene
gave adducts in moderate yields, while no product was obtained in the reaction
with
butyl
vinyl
ether.
The
Vilsmeier
reaction
gave
tetrafluorobenzo[c]thiophene-1-carbaldehyde in good yield. The aldehyde was
converted to tetrafluorothiabenzoporphyrin.
Dedicated to the great contribution to heterocyclic chemistry of Professor Dr. Ivar Ugi
INTRODUCTION
Polythiophenes and their related compounds have been attracting great interest from many scientists as
conducting polymers1 and light-emitting materials.2 Special attention has been paid for
poly(benzo[c]thiophene), because it has a very low-band gap (ca. 1.0 eV)3 and its almost-colorless thin
film doped with halogen shows high conductivity (ca. 50 Scm-1).4 These properties of polythiophenes
were easily modified by introduction of substituents on the thiophene ring such as alkyl, alkoxy, aryl, and
halogen groups.5 On the other hand, in the case of poly(benzo[c]thiophene), modification of the
properties was difficult due to lack of an efficient derivatization method of rather unstable 1,3-free
benzo[c]thiophene derivatives,6 preparation of which requires introduction of the aimed substituent before
construction of the heterocyclic ring system. Among the 1,3-free benzo[c]thiophene derivatives,
4,5,6,7-tetrafluorobenzo[c]thiophene (1) was reported to be much stable than parent benzo[c]thiophene7
due to the low HOMO level.8 Although its polymer9 and co-polymers10 with thiophene were

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investigated, intrinsic reactivity of 4,5,6,7-tetrafluorobenzo[c]thiophene was not reported so far. During
our study on preparation of compounds with a novel π-system for organic electronic materials,11 we
planned to utilize 4,5,6,7-tetrafluorobenzo[c]thiophene (1) as a synthon of tetrafluoro-o-quinodimethane.
In this paper, we discuss our results of its Diels-Alder and Vilsmeier reactions as well as preparation of
tetrafluorothiabenzoporphyrin.
RESULTS AND DISCUSSION
4,5,6,7-Tetrafluorobenzo[c]thiophene (1) was prepared in 30% overall yield from hexafluorobenzene
according to the literature procedure.7 The sublimed crystalline material of 1 was stable and stored in a
refrigerator without decomposition for a long time and, fortunately enough, was suitable for the X-ray
analysis.12,13 As far as we know, this X-ray analysis is the second example of benzo[c]thiophene
derivative with no substituent on the five-membered ring.14 The Ortep packing diagram and molecular
structure are shown in Figures 1 and 2. The molecules lie in a line along with C2 axes forming
molecular tapes (see Figure 1). Close contact [2.49(2) Å] is observed between the H1(H3) hydrogen and
F4(F7) fluorine atoms in the neighboring paralleling tapes forming a two-dimensional sheet. The sheets
are stacked in an anti-parallel fashion and the distance of the molecular planes of 1 in the neighboring
sheets is 3.337(2) Å.
In this crystal, the most reactive carbons at 1- and 3-positions of
benzo[c]thiophene are nicely protected by fluorine atoms of the stacking molecules. This may be one of
the reasons of great stability of 4,5,6,7-tetrafluorobenzo[c]thiophene (1).
Figure 1. Ortep packing diagram of 1. (a) View perpendicular to the bc plane;
(b) View perpendicular to the ab plane. (c) View perpendicular to the ac plane.

HETEROCYCLES, Vol. 73, 2007
675
Figure 2. Molecular network of 1.
The most striking feature is the bond lengths of 1 shown in Figure 2. Distinctive bond alteration is
observed even in the benzene ring; C4-C5(C6-C7) bonds [1.348(2) Å] are shorter than C5-C6 [1.428(2) Å]
and C3a-C4 (C7-C7a) bonds [1.414(2) Å], and the inner bond (C3a-C7a) is extremely elongated to be
1.443(2) Å. This fact means that the 10π-electron system of 2-benzothiophene overwhelms the local 6π
benzene aromaticity.15 The molecular structure was quite similar to that of a benzo[c]thiphene-Cr(CO)3
complex.14
First, we examined the Diels-Alder reactions of 1.
As the parent benzo[c]thiophene and
naphtho[2,3-c]thiophene smoothly reacted with electron-deficient dienophiles such as phenyl maleimide16
and 1,4-benzoquinone,17 the Diels-Alder reaction of 1 with 1,4-benzoquinone was conducted at room
temperature. However, no reaction was observed. Therefore, 1 and 1,4-benzoquinone was heated in
neat at 110 °C, and 9,10-epithioanthracenedione 2 and anthracenedione 3 were obtained in respective
yields of 24 and 5% (Scheme 1). From the NMR spectra of 2, this adduct was proved to consist of a ca.
1:1 mixture of endo and exo isomers. Stereochemistry of the endo and exo isomers could not be
determined by difference of the coupling constants between the bridge-head and carbonyl α-methine
protons,18 because exact determination of their coupling constants was difficult: the intrinsic spin system
F
F
F
F
F
F
O
O
F
F
O
O
F
F
SO2Ph
SO2Ph
F
F
F
F
F
F
i)
ii)
S
S
S
+
4
1
2
3
Scheme 1. Reagents and conditions: i) p-benzoquinone, 110 °C, 5 h; ii) bis(phenylsulfonyl)ethylene,
toluene, 140 °C, 14 h.

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HETEROCYCLES, Vol. 73, 2007
Figure 3. Ortep drawing of exo-2
of the symmetric bicyclo[2.2.1] skeletal system is AA’XX’ or AA’BB’. Moreover, the difference was
very small (ca. 1 Hz for one isomer and ca. 0 Hz for another isomer). On the other hand chemical shifts
were very informative for the determination: The olefinic protons of one isomer appeared at a higher field
(6.44 ppm) than those of anothor isomer (6.90 ppm) due to the anisotropic effect of the benzene ring.
Therefore, the former and the latter isomers were assigned to be endo and exo, respectively. Finally the
stereochemistry was unambiguously determined by the X-ray analysis of exo-2 (Figure 3).19 The other
product 3 was thought to be formed by thermal elimination of hydrogen sulfide from the adduct 2. The
product ratio of 3/2 was increased by elongation of the reaction time. When the reaction of 1 with
trans-bis(phenylsulfonyl)ethylene was conducted in toluene at 140 °C in a sealed tube, adduct 4 was
obtained in 36% yield. Contrary to these electron-deficient dienophiles, no reaction of 1 with butyl
vinyl ether was observed in spite of all of our efforts.
Next, we planned to prepare thiaporphyrin derivatives bearing a tetrafluorobenzo moiety by the [3+1]
porphyrin synthesis. As fluorine atoms on the tetrafluorobenzo moiety can be replaced by alkoxide and
alkylthiolate anions,20 tetrafluorothiabenzoporphyrin with long alkyl groups would become a versatile
starting compound for preparation of porphyrinoids with a discotic liquid-crystalline property.21 For this
HO
F
O
F
S
iv)
O
O
F
O
O
F
F
F
F
F
F
F
F
CHO
S
CHO
F
F
F
F
F
F
F
F
F
i)
ii)
iii)
S
S
S
8
v)
CHO
F
CHO
S
F
1
5
6
7
F
CHO
F
9
Scheme 2. Reagents and conditions: i) N-methylformanilide, POCl3, THF, rt. ii) ethylene glycol,
p-TSA, toluene, reflux. iii) n-BuLi, TMEDA; DMF, THF, -50 °C. iv) p-TSA, aq-acetone, reflux. v)
HCl, aq-THF, rt.

HETEROCYCLES, Vol. 73, 2007
677
purpose, we require a diformyl derivative of 1 and tripyrrane with long alkyl chains. Since pyrrole
derivatives could be diformylated under proper reaction conditions,22 we treated
4,5,6,7-tetrafluorobenzo[c]thiophene (1) with orthoformate derivatives under various reaction conditions.
However, no diformyl derivative was formed. We decided to make a detour to the dialdehyde (Scheme
2). The Vilsmeier reaction of 1 using N-methyl formanilide and phosphoryl chloride gave
4,5,6,7-tetrafluorobenzo[c]thiophene-1-carbaldehyde (5) in good yield (90%). Protection of the formyl
group as 1,3-dioxolane with ethylene glycol gave 6 in 95% yield.
Lithiation of
dioxolanylisothianaphthene 6 with n-BuLi and TMEDA followed by treatment with DMF afforded
aldehyde 7 in 80% yield. Deprotection of the dioxolanyl group of 7 was first carried out in aqueous
acetone in the presence of p-toluenesulfonic acid under reflux conditions. The aimed dialdehyde 9 was
not obtained at all, and acetone adduct 8, instead, was obtained in quantitative yield. The deprotection
of 7 was successfully done by changing the conditions (HCl in aq-THF at room temperature). The
aimed aldehyde 9 was obtained in quantitative yield. High susceptibility of the dialdehyde 9 toward the
nucleophilic attack even under acidic conditions was well understood by the o-quinonoid character of
benzo[c]thiophene.
Preparation of tripyrrane with long alkyl chains was examined. Due to availability of the starting
materials, we chose 3,4-dipentylpyrroles as a component of such a tripyrrane (Scheme 3). The Henry
reaction of hexanal and 1-nitrohexane gave a diastereomeric mixture of nitro alcohol 10 in 82% yield.
Acetylation of 10 followed by the Barton-Zard reaction23 with ethyl isocyanoatetate gave ethyl
pyrrole-1-carboxylate 12 in 66% yield (2 steps). Removal of the ester group gave 2,3-dipentylpyrrole
(13) in 74% yield. The Vilsmeier formylation of ethyl pyrrole-1-carboxylate 12 afforded formyl
compound 14 in 97% yield. Reduction of aldehyde 14 with NaBH4 in the presence of CeCl3 followed
n-C5H11
n-C5H11
1-nitrohexane
+
NO2
NO2
i)
ii)
iii)
v)
n-C5H11
n-C5H11
n-C5H11
n-C5H11
CO2Et
hexanal
N
H
OH
OAc
10
11
12
iv)
n-C5H11
n-C5H11
AcO
n-C5H11
HO
n-C5H11
OHC
n-C5H11
n-C5H11
n-C5H11
n-C5H11
vii)
vi)
CO2Et
CO2Et
CO2Et
N
H
N
N
N
H
H
H
16a
15
14
13
Scheme 3. Reagents and conditions: i) DBU, THF, rt. ii) Ac2O, H+, CHCl3, rt. iii) ethyl
isocyanoacetate, DBU, THF, rt. iv) KOH, ethylene glycol; 180 °C. v) DMF, POCl3, C2H4Cl2, 0 °C. vi)
NaBH4, CeCl3·7H2O, THF/EtOH, 0 °C. vii) Ac2O, pyridine, rt.

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n-C5H11
n-C5H11
R1
R2
CO2R3
R1
OAc
HN
n-C5H11
n-C5H11
NH
HN
i)
R2
CO2R3
+
NH
NH
16b
R1
CO2R3
13
R2
16a: R1 = R2 = n-C5H11; R3 = Et
16b: R1 = n-C4H9; R2 = Me; R3 = t-Bu
17a: R1 = R2 = n-C5H11; R3 = Et
17b: R1 = n-C4H9; R2 = Me; R3 = t-Bu
iii)
ii)
n-C4H9
n-C5H11
i)
16a
16a
Me
n-C5H11
NH
N
S
n-C5H11
n-C5H11
EtO2C
n-C5H11
n-C5H11
CO2Et
n-C5H11
n-C5H11
N
F
EtO
n-C4H9
HN
NH
CO2Et
N
F
H
Me
F
F
18
19
20
Scheme 4. Reagents and conditions: i) AcOH/EtOH, reflux. ii) AcOH/CF3CH2OH, reflux. iii) 9,
TFA, CH2Cl2, rt; Et3N; DDQ.
by acetylation with acetic anhydride in pyridine provided 5-acetoxymethyl derivative 16a in 96% yield (2
steps).
We attempted to prepare tripyrrane with six pentyl groups 17a by the condensation of α-free pyrrole 12
with acetoxymethylpyrrole carboxylate 16a (Scheme 4). When pyrroles 12 and 16a in acetic acid and
ethanol were refluxed according to the literature procedure,24 only 5-(ethoxymethyl)pyrrole 18 was
isolated instead of the targeted tripyrrane 17a. By changing the solvent system to a less nucleophilic
mixture of acetic acid and trifluoroethanol, dipyrromethane 19 was only obtained. We had already
encountered the similar technical difficulty in the preparation of a hexaethyl tripyrrane derivative: diethyl
hexamethyltripyrranedicarboxylate was prepared only in 29%, while the corresponding butyl methyl
tripyrrane derivative was obtained in 72% yield under the similar conditions.25 Therefore, we changed the
target to tripyrrane 17b. When pyrrole 13 was reacted with butyl methyl derivative 16b under the
similar conditions, the targeted tripyrrane 17b was obtained in 77% yield.
The [3+1] porphyrin synthesis of 4,5,6,7-tetrafluorobenzothiphene-1,3-dicarbaldehyde (9) with tripyrrane
17b was conducted under the usual conditions26 to give tetrafluorothiabenzoporphyrin 20 in 10% yield.
The UV-vis spectra of 20 and 12,13-diethyl-7,18-dibutyl-8,17-dimethylbenzo[b]porphyrin (21)27 are
shown in Figure 3. Thiabenzoporphyrin 20 showed a rather broad Soret absorption band at 417 nm

HETEROCYCLES, Vol. 73, 2007
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Figure 4. UV-vis spectra of thiabenzoporphyrin 20 (bold line) and benzoporphyrin 21 (solid line)
compared to benzoporphyrin 21 (404 nm). The Q band absorptions were observed at 495 (shoulder),
536, 571, 601, 613 (shoulder), and 661 nm. The lowest energy absorption band of 20 was 32-nm
bathochromically shifted from that of 21. This fact clearly suggests that the porphyrinoid π-system of
20 was expanded more effectively by incorporation of the benzo[c]thiophene moiety than by simple
fusion of the benzo moiety.
In conclusion, we utilized 4,5,6,7-tetrafluorobenzo[c]thiophene (1) as a building block for preparation of
tetrafluorobenzo-fused aromatic compounds. The first X-ray analysis of 1 explained the stability in
solid. Tetrafluorothiabenzoporphyrin was prepared and the π-system was revealed to be effectively
expanded.
EXPERIMENTAL
General
Melting points were measured on a Yanagimoto micromelting point apparatus and are uncorrected. NMR
spectra were obtained with a JEOL AL-400 or EX-400 spectrometer at the ambient temperature by using
CDCl3 as a solvent, tetramethylsilane as an internal standard for 1H and 13C, CFCl3 as a standard for 19F.
IR spectra were measured with a Horiba FT-720 infrared spectrophotometer. Mass spectra (EI, 70 eV)
were measured with a JEOL JMS-700. Elemental analyses were performed with a Yanaco MT-5
elemental analyzer. X-ray measurements of the single crystals were done with Rigaku AFC8S Mercury
CCD (1.5 kW Mo sealed tube). UV-vis spectra were measured in chlorofom with a HITACHI U-2810
spectrophotometer. Dehydrated tetrahydrofuran and dichloromethane were purchased from Kanto
Chemical Co. and used without further purification. Toluene and TMEDA were distilled from CaH2
under a nitrogen atmosphere and stored over molecular sieves 4A. DMF and DBU were distilled under

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a reduced pressure and stored over molecular sieves 13X. 1,4-Benzoquinone was sublimed under a
reduced pressure prior to use. Triethylamine and ethylene glycol were distilled prior to use. Potassium
tert-butoxide was sublimed at 200 °C under a reduced pressure (ca. 0.1 mmHg) and dissolved in dry THF
(1.0 mol L-1). Ethyl isocyanoacetate28 and trans-bis(phenylsulfonyl)ethylene29 were prepared according
to the literature procedures. Other commercially available materials were used without further
purification.
Diels-Alder reaction of 1 with p-benzoquinone
4,5,6,7-Tetrafluorobenzo[c]thiophene (1; 128 mg, 0.62 mmol) and p-benzoquinone (134 mg, 1.24 mmol)
was dissolved in CHCl3 (1 mL) and placed in a tube. After the solvent was mostly removed by
evaporation, the tube was sealed and heated at 110 °C for 5 h. After cooling, the mixture was
chromatographed on silica gel to give 5,6,7,8-tetrafluoro-1,4,4a,9,9a,10-hexahydro-9,10-
epithioanthracene-1,4-dione (2; 11 mg, 24%) and 5,6,7,8-tetrafluoroanthracene-1,4-dione (3; 3 mg, 5%).
2: yellow crystals, Rf 0.3 (15% EtOAc/hexane); νmax (KBr)/cm-1 1660, 1496, 1122, 1080, and 1033;
HRMS (EI) Calcd for C14H6F4O2S: 314.0025. Found: 314.0023. exo-2: mp >137 °C (decomp.); δH
(CDCl3) 3.30 (2H, s), 5.38 (2H, s), and 6.90 (2H, s); δF (CDCl3) -142.6 (2F, m) and -156.1 (2F, m).
endo-2: mp 126-129 °C; δH (CDCl3) 3.94 (2H, m), 5.38 (2H, m), and 6.44 (2H, s); δF (CDCl3) -142.4 (2F,
m) and -154.9 (2F, m). 3: yellow crystals, mp 117-119 °C, Rf 0.3 (15% EtOAc-hexane); δH (CDCl3)
7.15 (2H, m) and 8.88 (2H, m); δF (CDCl3) -145.5 (2F, m) and -151.9 (2F, m); νmax (KBr)/cm-1 1660,
1471, 1301, 1122, 1055, and 962; MS (EI) m/z (rel. intensity) 280 (M+, 100), 252 (20), 224 (74), and 198
(70). HRMS (EI) Calcd for C14H4F4O2: 280.0147. Found: 280.0148.
trans-5,6,7,8-Tetrafluoro-2,3-bis(phenylsulfonyl)-1,2,3,4-tetrahydro-1,4-epithionaphthalene (4)
A solution of 1 (102 mg, 0.48 mmol) and trans-bis(phenylsulfonyl)ethylene29 (410 mg, 1.33 mmol) in dry
toluene (12 mL) was placed in a sealed tube, the tube was flashed with nitrogen, and the tube was heated
at 140 °C for 14 h. After cooling, the solvent was removed and the residue was chromatographed on
silica gel to afford 59 mg (36%) of the title compound as pale yellow crystals: mp 159-162 °C, Rf 0.3
(30% EtOAc/hexane); δH (CDCl3) 4.10 (1H, d, J = 4.6 Hz), 4.90 (1H, m), 5.00 (1H, dd, J = 4.6 and 3.1
Hz), 5.27 (1H, br s), and 7.5-7.95 (10 H, m); δF (CDCl3) -139.9 (1F, t, J = 17 Hz), -142.5 (1F, t, J = 17
Hz), -154.9 (1F, t, J = 17 Hz), and -155.2 (1F, t, J = 17 Hz); νmax (KBr)/cm-1 1508, 1485, 1448, 1330,
1151, and 1079; MS (EI) m/z (rel. intensity) 514 (M+, 28), 373 (50), 309 (25), 247 (38), 231 (47), 200
(56), 141 (55), 125 (77), and 77 (100); HRMS (EI) Calcd for C22H14F4O2S3: 513.9990. Found: 513.9990.
4,5,6,7-Tetrafluorobenzo[c]thiophene-1-carbaldehyde (5)
To a stirred solution of N-methylformanilide (0.8 mL) was added POCl3 (1.0 mL) by a syringe at rt, and
the mixture was stirred for 30 min. A solution of 1 (300 mg, 1.46 mmol) in dry THF (5 mL) was added

HETEROCYCLES, Vol. 73, 2007
681
dropwise to the mixture. After being stirred for 6 h at rt, the reaction was quenched with water, and the
mixture was extracted with Et2O. The ethereal extract was washed successively with water and brine,
dried over Na2SO4, and concentrated in vacuo. The residue was chromatographed on silica gel to give 5
(285 mg, 90%) as yellow powdery crystals: mp 173-175 °C, Rf 0.7 (30% EtOAc/hexane); δH (CDCl3)
8.42 (1H, s) and 10.43 (1H, s); δC (CDCl3) 126.0 (dd, J = 17 and 5 Hz), 126.9 (dd, J = 19 and 8 Hz),
127.2 (d, J = 9 Hz), 135.0 (m), 136.7, (dt, J = 255 and 16 Hz), 138.7 (dm, J = 257 Hz), 139.7 (dm, J =
255 Hz), 140.4 (dtd, J = 259, 16, and 2 Hz), and 181.8 (d, J = 10 Hz); δF (CDCl3) -143.0 (t, J = 17 Hz),
-145.9 (t, J = 17 Hz), -158.3 (t, J = 17 Hz), and -160.7 (t, J = 17 Hz); νmax (KBr)/cm-1 1649, 1576, 1541,
1491, 1363, 1234, 1173, and 1034; MS (EI) m/z (rel. intensity) 234 (M+, 100), 206 (37), and 161 (31).
Anal. Calcd for C9H2F4OS: C, 46.16; H, 0.86. Found: C, 46.32; H, 1.26%.
1-(1,3-Dioxolan-2-yl)-4,5,6,7-tetrafluorobenzo[c]thiophene (6)
A solution of 5 (800 mg, 3.42 mmol), distilled ethylene glycol (0.40 mL, 7.0 mmol), and p-TSA·H2O (0.6
mg, 0.03 mmol) in dry THF (30 mL) was heated at reflux under N2 for 1.5 h with azeotropic removal of
water by a Dean-Stark apparatus filled with molecular sieves 4A. The mixture was cooled to rt, and an
aqueous solution of NaHCO3 was added. The organic layer was separated and aqueous layer was
extracted with ether. The combined ethereal extract was washed successively with water and brine, dried
over Na2SO4, and concentrated in vacuo. The residue was chromatographed on silica gel to give 904 mg
(95%) of 6 as white powder: mp 35-39 °C, Rf 0.3 (40% CHCl3/hexane); δH (CDCl3) 4.06-4.24 (4H, m),
6.65 (1H, s), and 7.82 (1H, s); δC (CDCl3) 65.6 (s), 98.9 (d, J = 6 Hz), 115.3 (d, J = 9 Hz), 122.4 (dd, J =
17 and 6 Hz), 126.5 (dd, J = 19 and 7 Hz), 133.8 (m), 136.2 (dt, J = 251 and 17 Hz), 137.6 (ddm, J = 248
and 17 Hz), 138.1 (ddm, J = 240 and 17 Hz), 138.8 (dm, J = 257 Hz), and 140.1 (dm, J = 13 Hz); δF
(CDCl3) -147.9 (t, J = 16 Hz), -148.9 (t, J = 16 Hz), -161.3 (t, J = 16 Hz), and -161.1 (t, J = 16 Hz); νmax
(KBr)/cm-1 1684, 1550, 1495, 1375, 1171, 1088, and 985; MS m/z (rel. intensity) 278 (M+, 100), 262 (77),
and 183 (66). Anal. Calcd for C11H6F4O2S: C, 47.49; H, 2.17. Found: C, 47.51; H, 2.22%.
3-(1,3-Dioxolan-2-yl)-4,5,6,7-tetrafluorobenzo[c]thiophene-1-carbaldehyde (7)
To a solution of 6 (780 mg, 2.80 mmol) and TMEDA (0.73 mL, 4.24 mmol) in THF (14 mL) was added
dropwise a 1.58-M hexane solution of n-BuLi (1.94 mL, 3.07 mmol) at -78 °C under N2, and the mixture
was stirred at -10 °C for 30 min. Dry DMF (0.33 mL, 4.3 mmol) was added at -50 °C and the mixture was
slowly warmed up to rt. The reaction mixture was quenched with an aqueous saturated solution of NH4Cl.
The mixture was extracted with Et2O. The ethereal extract was washed successively with water and brine,
dried over Na2SO4, and concentrated in vacuo. The residue was chromatographed on silica gel to give 682
mg (80%) of 7 as yellow powder, mp 106-109 °C, Rf 0.4 (60% CHCl3/hexane); δH (CDCl3) 4.13-4.21 (4H,
m), 6.68 (1H, s), and 10.42 (1H, s); δC (CDCl3) 56.9, 98.6 (d, J = 6 Hz), 123.0 (dd, J = 17 and 8 Hz),
127.0 (dd, J = 17 and 6 Hz), 132.9 (t, J = 9 Hz), 137.4 (dt, J = 254 and 17 Hz), 139.3 (dm, J = 259 Hz),

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139.9 (dt, J = 259 and 17 Hz), 147 (m), 182.2 (d, J = 11 Hz), and one carbon could not be found; δF
(CDCl3) -142.3 (t, J = 17 Hz), -143.8 (t, J = 17 Hz), -154.4 (t, J = 17 Hz), and -160.0 (t, J = 17 Hz); νmax
(KBr)/cm-1 1655, 1577, 1533, 1485, 1373, 1230, and 1146; MS (EI) m/z (rel. intensity) 306 (M+, 82), 234
(100), 217 (80), and 161 (36). Anal. Calcd for C12H4F4O3S: C, 47.49; H, 2.17. Found: C, 47.51; H,
2.22%.
4,5,6,7-Tetrafluoro-3-(3-oxo-1-hydroxybutyl)benzo[c]thiophene-1-carbaldehyde (8)
A solution of 7 (56 mg, 0.183 mmol) and p-toluenesulfonic acid (1 mg) in acetone (30 mL) and water (1
mL) was refluxed overnight under an inert atmosphere. After cooling, the mixture was concentrated to a
half volume and the residue was extracted with CHCl3. The organic extract was washed successively with
an aqueous NaHCO3, water, and brine, dried over Na2SO4, and concentrated in vacuo. The residue was
chromatographed on silica gel to give 58 mg (99%) of 8 as yellow powder: mp 124-126 °C, δH (CDCl3)
2.27 (3H, s), 2.86 (1H, dd, J = 18.2 and 9.8 Hz), 3.12 (1H, dt, J = 18.2 and 2.0 Hz), 4.24 (1H, d, J = 3.2
Hz; OH), 6.00 (1H, ddd, J = 9.8, 3.2 and 2.0 Hz), and 10.37 (1H, d, J = 1.6 Hz); δC (CDCl3) 30.6, 51.5,
66.3 (d, J = 5 Hz), 120.3 (dd, J = 16 and 8 Hz), 126.7 (dd, J = 17 and 6 Hz), 131.8 (m), 137.0 (dt, J = 258
and 16 Hz), 139.0 (m), 139.5 (m), 139.6 (m), 153.3 (m), 181.5 (d, J = 11 Hz), and 207.5; δF (CDCl3)
-141.9 (1F, t, J = 17 Hz), -145.7 (1F, t, J = 17 Hz), -154.7 (1F, t, J = 17 Hz), and -161.0 (1F, J = 17 Hz);
νmax (KBr)/cm-1 3253, 1716, 1627, 1490, 1240, 1147, and 1093; MS (EI) m/z (rel. intensity) 320 (M+, 14),
263 (72), 235 (100), 206 (30), 161 (33), and 157 (31). Anal. Calcd for C12H6F4O3S: C, 47.06; H, 1.97.
Found: C, 47.22; H, 2.12%.
4,5,6,7-Tetrafluorobenzo[c]thiophene-1,3-dicarbaldehyde (9)
To a stirred solution of 7 (670 mg, 2.19 mmol) in THF (24 mL) was added 1.5 M aqueous HCl (20 mL) at
rt. After 1 h, the mixture was extracted with CHCl3. The organic extract was washed successively with
aqueous NaHCO3, water, and brine, dried over Na2SO4, and concentrated in vacuo to give 574 mg
(100%) of 9 as yellow powder: mp 143-145 °C, Rf 0.4 (60% CHCl3/hexane); δH (CDCl3) 10.60 (s); δC
(CDCl3) 126.3 (t, J = 12 Hz), 139.6 (dm, J = 264 Hz), 140.0 (dm, J = 257 Hz), 141.0 (m), and 182.2 (t, J
= 6 Hz); δF (CDCl3) -140.1 (m) and -153.5 (m); νmax (KBr)/cm-1 1654, 1485, 1230, 1146, and 1066; MS
(EI) m/z (rel. intensity) 262 (M+, 100), 233 (36), and 161 (53). Anal. Calcd for C11H2F4O2S: C, 45.81; H,
0.77. Found: C, 45.75; H, 1.02%.
7-Nitro-6-dodecanol (10)
To a stirred solution of hexanal (6.98 mL, 50.0 mmol) and 1-nitrohexane (6.15 mL, 50.0 mmol) in THF
was added DBU (0.74 mL, 5.0 mmol) by a syringe at rt under nitrogen. After 8 h, a 1.0-M HCl solution
was added and then the mixture was extracted with EtOAc. The organic extract was washed successively
with water, a saturated aqueous NaHCO3, and brine, dried over Na2SO4, and concentrated in vacuo. The

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residual liquid was distilled under a reduced pressure and the distillate at 112-115 °C/0.01 mmHg was
collected to give 9.46 g (82 %) of diastereomeric 10 (6:4) as a pale yellow oil: Rf 0.25 (15%
EtOAc/hexane); δH (CDCl3) 0.90 (6H of both isomers, m), 1.2-1.6 (14H of both isomers, m), 1.65-2.1
(2H of both isomers, m), 2.1-2.6 (1H of both isomers, br m), 3.87 (1H of one isomer, m), 4.00 (1H of
another isomer, m), and 4,3-4.5 (1H of both isomers, m); δC (CDCl3) 13.8, 13.9, 22.2, 22.4, 24.9, 25.2,
25.3, 25.6, 27.9, 30.6, 31.0, 31.1, 31.4, 31.5, 33.1, 33.5, 72.1, 72.4, 92.4, and 92.9; νmax (KBr)/cm-1 3437,
1550, 1458, 1379, 1126, and 1072; FAB+ m/z 232 (M+H+). Anal. Calcd for C14H25NO4: C, 62.30; H,
10.89; N, 6.05. Found: C, 62.53; H, 10.75; N, 5.78%.
6-Acetoxy-7-nitrododecane (11)
To a stirred solution of 10 (9.25 g, 40.0 mmol) and acetic anhydride (5.67 mL, 60.0 mmol) was added
conc. H2SO4 (0.02 mL) at 0 °C. After the mixture had been stirred for 4 h at rt, a saturated aqueous
NaHCO3 was added and then the mixture was extracted with CHCl3. The organic extract was washed
successively with water and brine, dried over Na2SO4, and concentrated in vacuo. The residual liquid was
distilled under a reduced pressure and the distillate at 133-135 °C/0.01 mmHg was collected to give 8.96
g (82 %) of 11 (6:4) as a colorless oil: Rf 0.4 (15% EtOAc-hexane); δH (CDCl3) 0.89 (6H of both isomers,
m), 1.31 (10H of both isomers, m), 1. 5-1.75 (4H of both isomers, m), 2.00 (2H of both isomers, br m),
2.10 (3H of one isomer, s), 2.16 (3H of another isomer, s), 4.60 (1H of both isomers, m), 5.16 (1H of
another isomer, m), and 5.29 (1H of one isomer, m); δC (CDCl3) 13.77, 13.82, 20.65, 20.73, 22.2, 22.3,
24.2, 24.9, 25.2, 25.5, 28.9, 29.6, 29.7, 30.7, 30.96, 31.01, 31.2, 31.4, 72.7, 72.9, 89.6, 90.1, 169.8, and
170.2; νmax (KBr)/cm-1 2958, 2931, 2862, 1749, 1558, 1478, 1373, 1228, and 1122; FAB+ m/z 274
(M+H+). Anal. Calcd for C14H27NO4: C, 61.51; H, 9.96; N, 5.12. Found: C, 61.32; H, 9.75; N, 5.11%.
Ethyl 3,4-dipentylpyrrole-2-carboxylate (12)
To a stirred solution of 11 (8.20 g, 30.0 mmol) and ethyl isocyanoacetate (3.93 mL, 36.0 mmol) in dry
THF (30 mL) was added DBU (10.7 mL) (72.0 mmol) by a syringe at 0 °C under N2. The mixture was
warmed to rt and then stirred for 8 h. The reaction was quenched by adding a 1.0-M aqueous HCl solution.
The mixture was extracted three times with CHCl3. The organic extract was washed successively with a
saturated aqueous NaHCO3 and brine, dried over Na2SO4, and concentrated in vacuo. The residue was
chromatographed through a short silica-gel column with 15% EtOAc/hexane. The eluate was
concentrated, the residue was distilled under a reduced pressure, and the distillate at 142-144 °C/0.03
mmHg was collected to give 6.68 g (80%) of 12 as a pale yellow oil: Rf 0.2 (15% EtOAc/hexane); δH
(CDCl3) 0.90 (6H, m), 1.35 (11H, m), 1.52 (4H, m), 2.39 (2H, t, J = 7.8 Hz), 2.70 (2H, t, J = 7.8 Hz), 4.30
(2H, q, J = 7.2 Hz), 6.66 (1H, s), and 8.86 (1H, s, br); δC (CDCl3) 14.0, 14.1, 14.5, 22.5, 22.6, 24.8, 24.9,
30.3, 30.9, 31.7, 32.1, 59.7, 118.2, 119.6, 125.2, 131.3, and 161.6; νmax (KBr)/cm-1 3496, 3321, 1670,
1466, 1414, 1277, 1144, and 1117; MS (EI) m/z (rel. intensity) 279 (M+, 44), 223 (44), 207 (42), 166 (66),

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150 (88), 120 (39), and 94 (100). Anal. Calcd for C17H29N: C, 73.07; H, 10.46; N, 5.01. Found: C, 73.01;
H, 10.56; N, 5.00%.
3, 4-Dipentylpyrrole (13)
To ethyl pyrrolecarboxylate 12 (2.79 g, 10.0 mmol) were added KOH (2.0 g) and ethylene glycol (40 mL).
The mixture was heated at 180 °C under nitrogen. After 2 h, the mixture was cooled to rt and extracted
with EtOAc. The organic extract was washed successively with saturated aqueous NaHCO3 and brine,
dried over Na2SO4, and concentrated in vacuo. The residue was distilled under a reduced pressure and the
distillate at 95-97 °C/0.03 mmHg was collected to give 1.54 g (74 %) of 13 as a colorless oil: Rf 0.45
(15% EtOAc/hexane); δH (CDCl3) 0.90 (6H, t, J = 6.6 Hz), 1.35 (8H, m), 1.56 (4H, m), 2.41 (4H, t, J =
7.6 Hz), 6.50 (2H, s), and 7.76 (1H, br s); δC (CDCl3) 14.1, 22.6, 25.3, 30.2, 32.0, 114.8, and 123.1; νmax
(KBr)/cm-1 3496, 3392, 2956, 2927, 2856, 1460, and 1063; MS (EI) m/z (rel. intensity) 207 (M+, 33), 150
(44), 136 (12), 108 (22), and 94 (100). Anal. Calcd for C14H25N: C, 81.09; H, 12.15; N, 6.75. Found: C,
80.81; H, 12.25; N, 6.67%.
Ethyl 5-formyl -3,4-dipentylpyrrole-2-carboxylate (14)
To a solution of N,N-dimethylformamide (1.2 mL, 5.0 mmol) was added dropwise POCl3 (8.4 mL, 90
mmol) at 0 °C under a N2 atmosphere. The mixture was stirred at rt for 15 min and then the mixture was
diluted with 1,2-dichloroethane (50 mL). A solution of 12 (1.40 g, 5.00 mmol) in 1,2-dichloroethane (25
mL) was added dropwise to the reaction mixture at 0 °C and the mixture was then stirred at rt for 1.5 h.
An aqueous NaOAc was added at 0 °C and then the mixture was refluxed for 15 min. The mixture was
exacted with CH2Cl2 and the organic extract was washed successively with a saturated aqueous NaHCO3
and brine, dried over Na2SO4, and concentrated in vacuo. The residue was chromatographed on silica gel
with 20% EtOAc/hexane to give 14 (1.49 g, 97%) as colorless crystals: mp 55-57 °C, Rf 0.4 (20%
EtOAc/hexane); δH 0.90 (6H, m), 1.37 (11H, m), 1.54 (4H, m), 2.71 (4H, m), 4.36 (2H, q, J = 7.2 Hz),
9.54 (1H, brs), and 9.75 (1H, s); δC 13.9, 14.0, 14.3, 22.4, 22.5, 23.4, 24.4, 30.9, 31.7, 32.0, 32.4, 60.9,
124.6, 129.9, 131.9, 135.0, 160.7, and 179.2; νmax (KBr)/cm-1 3280, 1689, 1673, 1545, 1483, 1367, and
1257; MS (EI) m/z (rel. intensity) 307 (M+, 100), 278 (31), 251 (44), 234 (44), 194 (74), and 189 (25).
Anal. Calcd for C18H29NO3: C, 70.32; H, 9.51; N, 4.56. Found: C, 70.07; H, 9.34; N, 4.40%.
Ethyl 5-hydroxmethyl-3,4-dipentylpyrrole-2-carboxylate (15)
To a solution of 14 (1.23 g, 4.00 mmol) in dry THF (30 mL) was added CeCl3·7H2O (1.49 g, 4.00 mmol)
in EtOH (10 mL) at rt and then NaBH4 (0.15 g, 4.00 mmol) was added at 0 °C. The mixture was warmed
to rt and then stirred for 1 h. The reaction was quenched by adding a 1.0-M aqueous HCl solution. The
mixture was extracted three times with EtOAc. The organic extract was washed successively with
saturated aqueous NaHCO3 and brine, dried over Na2SO4, and concentrated in vacuo to give 15 (1.21 g,

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685
98%) as colorless powder: mp 98-100 °C, Rf 0.25 (40% EtOAc/hexane); δH 0.89 (6H, m), 1.34 (11H, m),
1.43 (2H, m), 1.51 (2H, m), 2.01 (1H, br s), 2.38 (2H, t, J = 7.6 Hz), 2.67 (2H, t, J = 8.1 Hz), 4.30 (2H, q,
J = 7.2 Hz), 4.64 (2H, s), and 9.18 (1H, br s); δC 14.0, 14.1, 14.7, 22.5, 22.6, 23.8, 25.1, 31.2, 31.7, 31.8,
32.2, 56.5, 59.9, 117.8, 122.2, 131.9, 132.3, and 161.8; νmax (KBr)/cm-1 3439, 3288, 1676, 1288, 1240,
and 1045; MS (EI) m/z (rel. intensity) 309 (M+, 100), 252 (70), 218 (68), 196 (97), 180 (66), and 150 (56).
Anal. Calcd for C18H31NO3: C, 69.86; H, 10.10; N, 4.53. Found: C, 69.61; H, 10.03; N, 4.52%.
Ethyl 5-acetoxymethyl-3,4-dipentylpyrrole-2-carboxylate (16a)
To a solution of 15 (309 mg, 1.00mmol) in dry pyridine (5 mL) was added acetic anhydride (5 mL) by a
syringe at rt under nitrogen. After 12 h, the mixture was vacuum distilled to remove the low boiling
components (pyridine, acetic anhydride, and acetic acid). The residue was chromatographed on silica gel
to give 16a (344 mg, 98%) as colorless powder: mp 77-79 °C; Rf 0.4 (20% EtOAc/hexane); δH 0.90 (6H,
m), 1.34 (11H, m), 1.50 (4H, m), 2.06 (3H, s), 2.42 (2H, t, J = 7.8 Hz), 2.67 (2H, t, J = 8.1 Hz), 4.32 (2H,
q, J = 7.2 Hz), 5.03 (2H, s), and 9.34 (1H, br s); δC 13.9, 14.0, 14.4, 20.8, 22.5, 23.7, 25.1, 31.1, 31.6,
31.7, 32.1, 57.1, 59.9, 118.8, 124.9, 126.9, 131.5, 161.5, and 171.4; νmax (KBr)/cm-1 3301, 1732, 1672,
1469, 1365, 1282, 1242, and 1020; MS (EI) m/z (rel intensity) 351 (M+, 100), 292 (56), 234 (47), 222 (40),
162 (35), and 150 (24). Anal. Calcd for C20H33NO3: C, 68.34; H, 9.46; N, 3.99. Found: C, 68.22; H, 9.34;
N, 4.03%.
2,5-Bis(5-t-butoxycarbonyl-3-butyl-4-methyl-2-pyrrolylmethyl)-3,4-dipentylpyrrole (17b)
To a solution of 3,4-dipentylpyrrole (13) (1.04 g, 5.00 mmol) and 16b27 (3.09 g, 10.0 mmol) in EtOH
(100 mL) was added AcOH (10 mL) at rt under a N2 atmosphere. The mixture was refluxed for 12 h.
After cooling, the mixture was diluted with EtOH and stirred at -40 °C. White precipitates were formed
and collected by filtration to afford 17b (2.71 g, 77%). This material was pure enough for the next step.
17b: pale yellow powder, mp 126-128 °C; δH (CDCl3) 0.88 (12H, m), 1.31 (16H, m), 1.43 (4H, m), 1.52
(18H, s), 2.23 (6H, s), 3.32 (8H, m), 3.47 (4H, s), 7.09 (1H, br s), and 8.34 (2H, br s); δC (CDCl3) 10.6,
13.9, 14.0, 22.5, 22.6, 23.1, 23.7, 24.6, 31.6, 32.1, 33.2, 80.1, 118.6, 120,2, 121.7, 122.2, 126.2, 129.9,
and 161.2; νmax (KBr)/cm-1 3448, 3309, 2925, 2856, 1655, 1365, and 1277; HRMS (FAB+): Calcd for
C44H71N3O4+H+: 706.5523; found: 706.5528.
Ethyl 5-ethoxymethyl-3,4-dipentylpyrrole-2-carboxylate (18)
To a solution of 3,4-dipentylpyrrole (13) (42 mg, 0.20 mmol) and 16a (141 g, 0.40 mmol) in EtOH (4.0
mL) was added AcOH (0.4 mL) at rt under a N2 atmosphere. The mixture was refluxed for 12 h. After
cooling, the mixture was extracted three times with EtOAc. The organic extract was washed successively
with water, saturated aqueous NaHCO3, and brine, dried over Na2SO4, and concentrated in vacuo. The
residue was chromatographed on silica gel with 20% EtOAc/hexane to give 14 (49 mg, 72%) as colorless

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HETEROCYCLES, Vol. 73, 2007
oil, Rf 0.5 (20% EtOAc/hexane); δH 0.89 (6H, m), 1.23 (3H, t, J = 7.1 Hz), 2.36 (2H, t, J = 7.8 Hz), 2.67
(2H, t, J = 7.8 Hz), 3.52 (2H, q, J = 7.0 Hz), 4.29 (2H, q, J = 7.2 Hz), 4.43 (2H, s), and 8.67 (1H, br s); δC
14.0, 14.1, 14.5, 15.2, 22.5, 22.6, 23.9, 25.1, 31.2, 31.5, 31.8, 32.2, 59.7, 63.8, 66.0, 117.8, 122.7, 129.7,
132.0, and 161.4; νmax (KBr)/cm-1 3313, 1707, 1666, 1458, 1371, 1342, 1247, 1171, and 1097; MS (EI)
m/z (rel. intensity) 337 (M+, 100), 292 (42), 281 (32), 236 (41), and 208 (32). HRMS (EI+): Calcd for
C20H35NO3: 337.2617; found: 337.2617.
Bis(5-ethoxycarbonyl-3,4-dipentyl-2-pyrrolyl)methane (19)
To a solution of 3,4-dipentylpyrrole (13) (42 mg, 0.20 mmol) and 16a (141 g, 0.40 mmol) in CF3CH2OH
(4.0 mL) was added AcOH (0.4 mL) at rt under a N2 atmosphere. The mixture was refluxed for 12 h.
After cooling, the mixture was extracted three times with EtOAc. The organic extract was washed
successively with water, saturated aqueous NaHCO3, and brine, dried over Na2SO4, and concentrated in
vacuo. The residue was chromatographed on silica gel with 20% EtOAc/hexane to give 14 (86 mg, 76%)
as white solid, mp 51-53 °C; Rf 0.4 (20% EtOAc/hexane); δH 0.88 (12H, m), 1.28-1.34 (22H, m), 1.50 (4H,
m), 1.62 (4H, m), 2.33 (4H, m), 2.65 (4H, m), 3.83 (2H, s), 4.25 (4H, q, J = 7.2 Hz), and 8.67 (2H, brs);
δC 14.0, 14.1, 14.5, 22.5, 22.6, 23.4, 24.1, 25.3, 31.20, 31.23, 31.9, 32.4, 59.7, 117.5, 122.5, 129.0, 132.6,
and 161.5; νmax (KBr)/cm-1 3302, 1651, 1442, 1313, 1250, and 1043; MS (EI) m/z (rel. intensity) 570 (M+,
100), 291 (43), 222 (5), 162 (4), and 134 (4). Anal. Calcd for C35H58N2O4: C, 73.64; H, 10.24; N, 4.91.
Found: C, 73.34; H, 10.22; N, 4.91%.
8,18-Butyl-7,17-dimethyl-12,13-dipentyl-21,22,23,24-tetrafluoro-23H,21-thiabenzo[b]porphyrin (20)
A solution of tripyrrane 17b (79.2 mg, 0.11 mmol) in trifluoroacetic acid (0.20 mL) was stirred at rt for
15 min under N2 in the dark. The mixture was diluted with dry CH2Cl2 (7.0 mL), and then a solution of
diformylbenzo[c]thiophene 9 (29 mg, 0.11 mmol) in dry CH2Cl2 (3.0 mL) was added. The mixture was
stirred at rt for 16 h. The reaction mixture was neutralized with triethylamine and treated with DDQ (27.2
mg, 0.12 mmol) for 2 h. The mixture was washed successively with water and brine, dried over Na2SO4,
and concentrated in vacuo. The residue was chromatographed on silica gel with EtOAc/hexane and
recrystallization of CH2Cl2/MeOH gave 20 (8.2 mg, 10%) as purple crystals: mp >250 °C (decomp); δH
(CDCl3) -3.10 (1H, br s), 1.03 (6H, t, J = 7.3 Hz), 1.15 (6H, t, J = 7.3 Hz), 1.60 (4H, m), 1.80 (8H, m),
2.23 (4H, m), 2,32 (4H, m), 3.25 (6H, s), 3,82 (4H, t, J = 7.6 Hz), 4.07 (4H, t, J = 7.8 Hz), 9.96 (2H, s),
and 10.27 (2H, s); δC (CDCl3) 11.3, 14.1, 14.2, 22.8, 23.2, 26.2, 26.5, 32.5, 33.6, 35.3, 103.3, 110.9 (m),
121.4 (m), 135.3, 137.2, 137.9 (dm, J = 253 Hz), 138.1, 138.5, 141.9 (dm, J = 266 Hz), 144.7, 151.8, and
157.4; δF (CDCl3) -144.2 (2F, m) and -158.1 (2F, m); UV-vis (CHCl3) λmax/nm (log10 ε): 318 (4.40), 417
(5.20), 495 (sh, 3.75), 5.36 (4.13), 571 (4.53), 6.01 (3.94), 6.13 (sh, 3.81), and 661 (3.90). HRMS (FAB+)
Calcd for C44H51N3F4S+H+: 730.3818; found: 730.3817. Anal. Calcd for C44H51F4N3S4+1/8CH2Cl2: C,
71.56; H, 6.98; N, 5.67. Found: C, 71.68; H, 6.80; N, 5.57%.

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ACKNOWLEDGEMENTS
This work was partially supported by Grant-in-Aid for Scientific Research B (17350022) from Ministry
of Education, Culture, Sports, Science and Technology of Japan.
REFERENCES AND NOTES
1. For reviews, see: A. G. MacDiarmid, Angew. Chem Int. Ed., 2001, 40, 2581; A. J. Heeger, Angew.
Chem Int. Ed., 2001, 40, 2591.
2. I. F. Perepichka, D. F. Perepichka, H. Meng, and F. Wudl, Adv. Mater., 2005, 17, 2281.
3. F. Wudl, M. Kobayashi, and A. J. Heeger, J. Org. Chem., 1984, 49, 3382.
4. M. Kobayashi, N. Colaneri, M. Boysel, F. Wudl, and A. Heeger, J. Chem. Phys., 1985, 82, 5717.
5. G. Barbarella, M. Melucci, and G. Sotgiu, Adv. Mater., 2005, 17, 1581; J. Roncali, P. Blanchard, and
P. Frère, J. Mater. Chem., 2005, 15, 1589.
6. T. L. Gilchrist and S. J. Higgins, “Benzo[c]thiophenes,” in “Hetarenes and Related Ring Systems,
Fused Five-Membered Hetarenes with One Heteroatom,” E. J. Thomas, ed in a series of “Science of
Synthesis,” George Thieme Verlag, Stuttgart, 2000, 10.5, 185.
7. G. M. Brooke and S. D. Mawson, J. Chem. Soc., Perkin Trans. 1, 1990, 1919; G. M. Brooke and J.
A. K. J. Ferguson, J. Fluorine Chem., 1988, 41, 263.
8. F. Babudri, G. M. Farinola, F. Naso, and R. Ragni, Chem. Commun., 2007, 1003.
9. G. M. Brooke, C. J. Drury, D. Bloor, and M. J. Swann, J. Mater. Chem., 1995, 5, 1317; R. Kiebooms,
P. Adriaensens, D. Vanderzande, J. Gelan, M. J. Swann, D. Bloor, C. J. Drury, and G. M. Brooke,
Macromolecules, 1996, 29, 5981.
10. R. H. L. Kiebooms, P. J. A. Adriaensens, D. J. M. Vanderzande, and J. M. J. V. Gelan, J. Org.
Chem., 1997, 62, 1473.
11. For a recent example, see: H. Uno, K. Nakamoto, K. Kuroki, A. Fujimoto, and N. Ono, Chem. Eur.
J., 2007, 13, 5773.
12. Crystallographical data for 1: C8H3F4S; FW = 206.16, colorless blocks, 0.30 x 0.30 x 0.20 mm,
monoclinic, C2/c (#15), Z = 4 in a cell of dimensions a = 12.771(4) Å, b = 9.219(2) Å, c = 7.086(6)
Å, β = 117.604(1)˚, V = 739.3(7) Å3, Dcalc = 1.852 g·cm-3, Mo Kα, F(000) = 408, T = 150, 830
unique reflections, 691 with F2 > 2σ(F2). The final R1 = 0.040, wR2 (all) = 0.103, goodness-of-fit =
1.01 for 65 parameters refined on F2, CCDC No. 650401.
13. X-Ray data were processed by CrystalStructure Ver. 3.8.1. Structures were solved by SIR-97 and
then refined by SHELXL-97. CrystalStructure Ver. 3.8.1, Crystal Structure Analysis Package,
Rigaku (3-9-12 Akishima, Tokyo, Japan) and Rigaku/MSC (9009 New Trails Dr., The Woodlands,
TX 77381 USA), (2006). SIR-97: A package for crystal structure solution and refinement, Istituto di

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Gristallografia, Italy; A. Altomare, M. C. Burla, M. Camalli, G. Cascarano, C. Giacovazzo, A.
Guagliardi, A. G. G. Moliterni, G. Polidori, and R. Spagna, J. Appl. Cryst., 1999, 32, 115.
SHELXL-97: Program for the refinement of crystal structures from diffraction data, University of
Göttingen, Göttingen, Germany; G. Sheldrick and T. Schneider, Methods Enzymol., 1997, 277, 319.
14. J. P. Selegue and K. A. Swarat, J. Am. Chem. Soc., 1993, 115, 6448.
15. M. Szajda and J. N. Lam,“Comprehensive Heterocyclic Chemistry II” A. R. Katritzky, C. W. Rees,
and E. F. V. Scriven, eds, Pergamon, Oxford, 1996, Vol 2. 2.09.
16. D. W. H. MacDowell, A. T. Jeffries, and M. B. Meyers, J. Org. Chem., 1971, 36, 1416.
17. H. F. G. Linde and N. H. Kämer, Archiv Pharm., 1990, 323, 295.
18. A. P. Marchand, “Stereochemical Application of NMR Studies in Rigid Bicyclic Systems,” in
“Methods in Stereochemical Analysis,” A. P. Marchand ed, Verlag Chemie Int. Inc., Deerfield Beach,
1982, Vol. 1.
19. Crystallographical data for exo-2: C14H6F4O2S; FW = 314.25, colorless platelets, 0.22 x 0.12x 0.03
mm, monoclinic, P21/c (#14), Z = 4 in a cell of dimensions a = 13.352(2) Å, b = 6.3727(9) Å, c =
13.878(2) Å, β = 94.196(3)˚, V = 1177.7(3) Å3, Dcalc = 1.772 g·cm-3, Mo Kα, F(000) = 632, T = 150,
2683 unique reflections, 2126 with F2 > 2σ(F2). The final R1 = 0.058, wR2 (all) = 0.169,
goodness-of-fit = 1.09 for 191 parameters refined on F2, CCDC No. 656409.
20. M. Matsui, S. Taniguchi, M. Suzuki, M. Wang, K. Funabiki, and H. Shiozaki, Dyes and Pigments,
2005, 65, 211; L. M. Gornostaev, T. I. Lavrikova, and E. V. Arnold, Zh. Org. Khim., 1992, 28, 2291.
21. T. Murashima, N. Wakamori, Y. Uchihara, T. Ogawa, H. Uno, and N. Ono, Mol. Cryst. Liq. Cryst.,
1996, 278, 165.
22. Y. Shimizu, Z. Shen, S. Ito, H. Uno, J. Daub, and N. Ono, Tetrahedron Lett., 2002, 43, 8485.
23. D. H. R. Barton and S. Z. Zard, J. Chem. Soc., Chem. Commun., 1985, 1098.
24. T. D. Lash, P. Chandrasekar, A. T. Osuma, S. T. Chaney, and J. D. Spence, J. Org. Chem., 1998, 63,
8455.
25. H. Uno, K. Nakamoto, K. Kuroki, A. Fujimoto, and N. Ono, Chem. Eur. J., 2007, 13, 5773.
26. A. Boudif and M. Momentou, J. Chem. Soc., Chem. Commun., 1994, 2069; J. L. Sessler, J. W.
Genge, A. Urbach, and P. Sanson, Synlett, 1996, 187.
27. S. Ito, N. Ochi, T. Murashima, H. Uno, and N. Ono, Heterocycles, 2000, 52, 399; T. Itoh, T.
Murashima, H. Uno, and N. Ono, J. Chem. Soc., Chem. Commun., 1998, 1661.
28. G. D. Hatman and L. M. Weinstock, Org. Synth., Coll. Vol., 1988, 6, 620.
29. O. De Lucchi, V. Lucchini, L. Pasquato, and G. Modena, J. Org. Chem., 1984, 49, 596.