Synthesis of highly functionalized BEDT-TTF analogues incorporating 1,4-dithiin rings from 1,8-diketones

Article abstract of DOI:10.1016/j.tet.2008.08.085

Employment of 1,8-diketone ring formation reaction led to the synthesis of tetrathiafulvalene derivatives having diphenyl-1,4-dithiin ring together with dihydroxyl, dimethyl, MEM and diphenylthiophene groups. Spectroelectrochemistry of ET and its fully unsaturated analogue 4 was compared. While both displayed nearly similar behaviours, ET started to precipitate as the second oxidation potential is reached. CV studies indicated that the fully unsaturated 4 and tetraphenyldithiophene 20 have the highest oxidation potentials, while diphenyldithiindimethylthio 16 displayed the lowest oxidation potentials. CV measurements indicated that the combination of dithiin and hydroxyl groups help lowering the oxidation potentials. It is surprising that while the presence of dithiin ring results in higher oxidation potentials, hydroxyl groups lower the potentials. Single crystal structure of 13, having both dithiin and 1,4-dithiepine rings, was examined and it was observed that dithiin and dithiepine rings form angles of 20.52° and 25.65° with the planar TTF core in cis form as both rings bent about their S?S axis to give a boat conformation.

Full text of DOI:10.1016/j.tet.2008.08.085

Tetrahedron 64 (2008) 10581–10589
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis of highly functionalized BEDT-TTF analogues incorporating
1,4-dithiin rings from 1,8-diketones
,
Erdal Ertas a, F. Betul Kaynak b, Suheyla Ozbey b, Ipek Osken c, Turan Ozturk c
*
a Tubitak, Marmara Research Centre, FSRTI, 41470 Gebze Kocaeli, Turkey
b Hacettepe University, Department of Engineering Physics, 06532 Beytepe Ankara, Turkey
c Istanbul Technical University, Science Faculty, Chemistry Department, Organic Chemistry, 34469 Maslak, Istanbul, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 29 May 2008
Received in revised form 8 August 2008
Accepted 27 August 2008
Available online 4 September 2008
Employment of 1,8-diketone ring formation reaction led to the synthesis of tetrathiafulvalene derivatives
having diphenyl-1,4-dithiin ring together with dihydroxyl, dimethyl, MEM and diphenylthiophene
groups. Spectroelectrochemistry of ET and its fully unsaturated analogue 4 was compared. While both
displayed nearly similar behaviours, ET started to precipitate as the second oxidation potential is reached.
CV studies indicated that the fully unsaturated 4 and tetraphenyldithiophene 20 have the highest oxi-
dation potentials, while diphenyldithiindimethylthio 16 displayed the lowest oxidation potentials. CV
measurements indicated that the combination of dithiin and hydroxyl groups help lowering the oxi-
dation potentials. It is surprising that while the presence of dithiin ring results in higher oxidation
potentials, hydroxyl groups lower the potentials. Single crystal structure of 13, having both dithiin and
1,4-dithiepine rings, was examined and it was observed that dithiin and dithiepine rings form angles of
20.52ꢀ and 25.65ꢀ with the planar TTF core in cis form as both rings bent about their S/S axis to give
a boat conformation.
Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction
dendrimers,7–9 phthalocyanines,7,8 polymers10 and supramolecular
switches.11
Since the discovery of superconductivity of
b
-(BEDT-TTF)2I3
So far, extension has mostly been demonstrated in the middle of
the molecule with an increased conjugation, which would allow
the system to have an extended delocalization of the dication
formed in the TTF moiety after reaching the second oxidation
state.2b However, although there are some examples of in-
troduction of conjugation at the peripheral ethylene groups, such
an exploration has remained limited.12 There are two reasons for
this, lack of convenient methods and, at first sight, extension in
TTF core looks more useful as the dication forms in the TTF
moiety. On the other hand, it could equally be important to explore
any expansion at the peripheries since such compounds have now
been accepted as useful electron donors and find various
applications.4b,13
Recently, we have reported a convenient method for syn-
thesizing fused 1,4-dithiin rings with various functional groups
2.14 It involves an interesting ring formation reaction from 1,8-
diketone with Lawesson’s reagent (LR) 3 or P4S10. Employment
of this reaction led to the synthesis of the dithiin 5 and its
coupling resulted in, to our best knowledge, the first example
of BEDT-TTF analogue having the highest conjugation at the
peripheries.15,16
with a transition temperature of 1.4 K at atmospheric pressure,
there has been great deal of effort to improve and understand
the properties of related multi-sulfur
p
-donors.1 Bis(ethylenedi-
thio)tetrathiafulvalene (BEDT-TTF or ET) 1 is among the most
widely used and derivatized electron donor molecules for
the synthesis of organic materials, which show electrical con-
ductivity, semi conductivity and, at very low temperatures,
superconductivity.2,3
It appears that two important features, a highly ordered crystal
structure of the charge transfer salts and the extension of the
donor molecules, are the central points to improve the properties
of ET.2b Studies to implement such properties to a single molecule
by molecular design have led to the development of various ad-
vanced materials,4,2b,c including analogues having different po-
tential applications such as nonlinear optics,5 liquid crystals,6
* Corresponding author. Tel.: þ90 212 285 69 94; fax: þ90 212 285 63 86.
E-mail address: ozturktur@itu.edu.tr (T. Ozturk).
0040-4020/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.08.085

10582
E. Ertas et al. / Tetrahedron 64 (2008) 10581–10589
S
S
R1
R2
ring closure reaction was then performed using P4S10 in dry toluene
under a nitrogen atmosphere and in the dark, which was com-
pleted in 3 h. As it was reported earlier,16 this reaction gave three
products; benzylphenyldithiole 9 (trace), thiophene 10 (20%) and
1,4-dithiin 5 (65%), structures of which were confirmed by X-ray
single crystal diffraction analysis.20
S
S
S
S
S
S
S
S
R1=Ph, 4-CH3OPh, 4-NO2Ph
CH3, 4-BrPh; R2=H
1
R1=R2=Ph
2
S
P
The thione sulfur atom of 5,6-diphenyl[1,3]dithiolo[4,5-
b][1,4]dithiine-2-thione 5 was converted to oxygen with mercuric
acetate to obtain 11, which was then subjected to self-coupling
(Scheme 2) and couplings with the reaily available precursors such
as MEM protected dihydroxymethyldithiolodithiepinone 1218b and
dimethylthiodithiolone 15 (Scheme 3).21
S
S
CH3O
P
S
OCH3
3
S
S
S
S
S
S
S
S
4
S
S
S
S
S
S
S
S
S
S
S
S
S
9
10
S
5
In our previous studies, we developed mono,17 di, tri and tetra
hydroxyl analogues of BEDT-TTF18 to introduce hydrogen bonding
functionalities into the radical cation salts, which could provide the
charge transfer salts with highly ordered crystal structures. We
report here, in addition to the fully unsaturated tetraphenyl ET
analogue (TPhET) 4, the synthesis and properties of the analogues
having dimethoxyethoxymethyldiphenyldithiin 13, diphenyldi-
thiindithiomethyl 16, dihydroxydiphenyldithiin 21, dimethoxy-
ethoxymethyldiphenylthiophene 19 and dihydroxydiphenylthiop
hene 22 groups at the peripheries.
S
S
a
O
S
S
11
b
4
Scheme 2. Reagents and conditions: (a) Hg(OAc)2, AcOH; (b) P(OEt)3, N2, reflux.
2. Results and discussion
2.1. Synthesis
The coupling reactions were performed in neat triethylphos-
phite at 110 ꢀC for 2 h (Schemes 2 and 3). While the self-coupling
reaction yielded 4 in 90% as the only product, the coupling reactions
with 12 and 15 produced mixtures of self and cross-couplings
(Scheme 3). Thus, the reaction of 11 with 12 gave a mixture of cross-
coupled 13 and self-coupled products 1418b and 4, and the reaction
with 15 produced, in the same way, a mixture of cross-coupled 16
and self-coupled products 1721 and 4. Their separation was suc-
cessfully achieved by column chromatography.
Synthesis of 4 was achieved by employing the 1,8-diketone ring
formation reaction on BEDT-TTF 1.14,16 The readily available dianion
619 was reacted with desyl chloride 7 in dry THF at room temper-
ature, which gave the 1,8-diketone 8 (Scheme 1) in 90% yield. The
In the same way, the thione sulfur atom of 5,6-diphenyl-
thieno[3,2-d][1,3]dithiole-2-thione 10 was converted to oxygen
using mercuric acetate to obtain 18, coupling reaction of which
with dihydroxymethyldithiolodithiepinone 12 gave three coupling
products, cross-coupled 19 and self-coupled products 2015b and 14
(Scheme 4). Removal of MEM protecting groups of 13 and 19 was
carried out in acid (20% HCl/THF, 1:1) to obtain diphenyldihydroxy
ET analogues 21 and 22, respectively (Scheme 5). In a previous
study, it was reported that when saturated analogue 23 was sub-
SNa
SNa
S
S
Cl
S
+
O
6
7
a
jected to
a coupling reaction, rather than self-coupled 25,
tetrakis(ethylthio)tetrathiafulvalene 24 was obtained.15a,c On the
other hand, in our case, coupling of 11 smoothly gave fully un-
saturated analogue of ET with four phenyls at the peripheries.
Moreover, ET analogues having dithiin rings with one phenyl group,
26 and 27 were obtained in our previous studies without any
problem.14b These results suggest that the unsaturated dithiin ring
contributes to the stability of the molecule through conjugation.
Attempts for the self or cross-couplings of 28 having a benzyl-
phenyldithole ring, obtained through the reaction of 9 with mercury
acetate, with 15, unfortunately did not yield any products as 29 and
30, respectively, except many spots on TLC, which could not be
identified (Scheme 6). A possible explanation could be the presence
of a quaternary benzylic carbon, which is susceptible to any
O
O
S
S
S
S
S
8
b
5
Scheme 1. Reagents and conditions: (a) THF (dry), rt, 3 h; (b) P4S10, toluene (dry), N2,
reflux, dark, 3 h.

E. Ertas et al. / Tetrahedron 64 (2008) 10581–10589
10583
OMEM
OMEM
OMEM
S
S
S
S
S
S
S
S
S
S
+
O
11
S
S
OMEM
12
13
+
+
OMEM
OMEM
S
SCH3
SCH3
S
S
S
O
(
2
S
S
14
15
+
4
SCH3
S
SCH3
SCH3
S
S
S
S
S
4
+
(
+
2
S
SCH3
S
16
MEM=OCH2OCH2CH2OCH3
Scheme 3. Reagents and conditions: P(OEt)3, N2, reflux.
17
nucleophilic attack, which can easily be performed by triethyl-
phosphite and the resultant product can end up with various side
reactions.
a
S
S
10
O
S
18
S
S
SEt
SEt
S
S
EtS
EtS
S
S
S
S
S
b
24
23
OMEM
OMEM
S
S
S
S
S
S
S
S
S
S
S
S
S
S
19
S
S
25
+
S
S
S
S
)
+
14
S
S
S
2
S
S
S
20
26
Scheme 4. Reagents and conditions: (a) Hg(OAc)2, AcOH; (b) 12, P(OEt)3, N2, reflux.
S
S
CH3S
CH3S
S
S
S
S
4
¼34(4)ꢀ] and C10[Q¼0.275(15) Å,
4
¼214(3)ꢀ].22 The dithiine ring
is bent about the S/S axis to give a boat conformation with the S
27
atoms at the apices [Q¼0.702(13) Å,
q
¼90(3)ꢀ,
4
¼181(2)ꢀ]. The di-
hedral angle between S2/C2/C3/S3 and C2/C3/C4/C5 is 30.0(6)ꢀ. The
seven membered ring fused to one of the dithiolane rings also
deviates from planarity and the angle between S20/C20/C30/S30 and
S40/C20/C30/S50 is 1.4(3)ꢀ. The phenyl groups make dihedral angles
Mono aryl analogues 34–36 having dihydoxy groups were pre-
pared following the usual methodology to compare the CV mea-
surements of both diaryl and mono aryl compounds (Scheme 7).
The readily available mono aryl dithiins 3114b were coupled with
the MEM protected dihydroxyl 12 in refluxing P(OEt)3. Chromato-
graphic separation of the resultant crude product yielded three
compounds, cross-coupled 33 and self-coupled products 32 and 14.
Removal of the MEM protecting group of 33 was carried out in acid
(20% HCl/THF, 1:1) to obtain phenyldihydroxy ET analogues 34–36.
OH
S
S
S
S
S
S
S
S
13
OH
21
2.2. X-ray crystallography
The X-ray structure and molecular packing of 13 are shown in
Figures 1 and 2, respectively. Some selected geometric parameters
are given in Table 1.
The angle between the best planes of the dithiolane rings of 13 is
48.6(6)ꢀ. The calculated puckering parameters show that both
dithiolane rings are in an envelope conformation on C1 [Q¼0.243(15) Å,
OH
OH
S
S
S
19
S
S
S
S
22
Scheme 5. Reagents and conditions: THF/HCl (1:1), rt.

10584
E. Ertas et al. / Tetrahedron 64 (2008) 10581–10589
S
S
S
S
O
S
S
S
2
S
28
29 (cis + trans)
15
SCH3
SCH3
S
S
S
S
S
S
30
Scheme 6.
Figure 2.
R
S
S
S
Table 1
O
S
Selected geometric parameters for 13 (Å, ꢀ
)
12
+
S20–C10
S20–C20
S30–C10
S30–C30
S5–C3
1.754(18)
1.767(19)
1.754(17)
1.759(18)
1.738(17)
1.792(18)
1.752(17)
1.801(18)
1.746(18)
1.760(17)
1.754(17)
1.774(18)
1.738(18)
1.81(2)
1.76(2)
1.761(17)
1.35(2)
1.33(2)
1.33(2)
1.34(2)
174.9(16)
176.6(15)
31 R= H, Br, CH3O
a
R
S5–C4
S4–C2
S4–C5
S2–C2
S2–C1
S3–C1
S3–C3
S40–C20
S40–C18
S50–C20
S50–C30
C1–C10
C4–C5
C30–C20
C3–C2
S5–C4–C5–C6
C12–C4–C5–S4
S
S
14
+
2
S
S
32 cis + trans
+
R
R
OMEM
OMEM
S
S
S
S
S
S
S
S
33
b
OH
OH
S
S
S
S
S
S
S
S
34 R= H, 35 R= Br, 36 R= CH3O
Scheme 7. Reagents and conditions: (a) P(OEt)3, N2, reflux; (b) THF/HCl (1:1), rt.
of 41.6(9)ꢀ and 73.3(7)ꢀ with the best plane of the dithiin ring [C2/
C3/C4/C5].
As depicted in Figure 3. the mean heterocycle of the molecule is
not planar. Each moiety in the mean heterocycle, S2–C1–S3–C10–
Figure 3. CV of 4 (1.0ꢁ10ꢂ3 M) in 0.1 M TBABF4/CH2Cl2 with a scan rate of 100 mV sꢂ1
,
Pt working, Pt counter and Ag/Agþ reference electrodes.
Figure 1.

E. Ertas et al. / Tetrahedron 64 (2008) 10581–10589
10585
S20–S30 (Line 1), S2–S3–C2–C3–S4–S5 (Line 2) and S2–S30–C20–C30–
S40–S50 (Line 3) can be assumed planar, independently. Maximum
deviations from planarity are 0.028(5) Å for S3 for Line 1,
ꢂ0.073(18) Å for C2 for Line 2 and 0.021(6) Å for S50 for Line 3. The
angle between Line 1 and Line 2 is 20.52(14)ꢀ and the angle be-
tween Line 1 and Line 3 is 25.65(11)ꢀ.
The packing arrangement of 13 is shown in Figure 2. As usual in
this type of compounds, packing appears to be governed by short
S/S interactions. Two especially short S/S contacts, S5/S50 (1ꢂx,
ꢂy, 1ꢂz) 3.473(4) Å and S2/S20 (1ꢂx, 1ꢂy, 1ꢂz) 3.576(4) Å, are less
than that (3.6 Å) predicted from traditional Van der Waals radii.
Some other close S/S contacts are S4/S40 (ꢂx, 1ꢂy, 1ꢂz)
3.601(4) Å and S30/S5 (1þx, y, z) 3.731(4) Å. The intramolecular
close contacts are S2/S20 3.273(7) Å and S3/S30 3.261(7) Å.
the oxidation potentials higher. Similarly, diphenylthiophene rings
do not contribute to lower the oxidation potentials.
It could be concluded that (i) the presence of bis(diphenyldi-
thiin) and bis(diphenylthiophene) rings do not make the oxidations
easier; (ii) the combination of diphenyldithiin and dimethylthio
lower the oxidation potential; (iii) the presence of hydroxyl groups,
in general lower the oxidation potential (typical example could be
the comparison of 26 and 37); (iii) also the combination of diphe-
nyldithiin and dihydroxyl groups lower the oxidation potentials.
OH
S
S
S
S
S
S
S
S
OH
37
2.4. Spectroelectrochemical studies
2.3. Cyclic voltammetry (CV) measurements
To the best of our knowledge, this is the first spectroelec-
trochemical report of an ET analogue involving a comparison with
ET. Spectroelectrochemical experiments of both ET 1 and TPhET 4
were performed in CH2Cl2 solution as ET has better solubility,
containing 0.1 M TBABF4. First and second oxidation potentials of
ET and TPhET were recorded as 0.79, 1.15 V and 0.86, 1.14 V, re-
spectively. Neutral UVs of ET and TPhET showed absorptions at 236,
321 and 347 nm (Fig. 4) and 241, 300 and 339 nm (Fig. 5),
respectively.
Oxidation potentials of the new organosulfur donors 4, 13, 16,
19, 20–22 and 34–36 were measured by cyclic voltammetry and
compared with the data for ET 1, along with the analogues 26, 27
and 37, reported previously14b,18b (Table 2). The measurements
were performed in acetonitrile containing NaClO4. CV measure-
ments showed that while the ET analogue having diphenyldithiin
ring and dimethyl groups 16 had the lowest oxidation potentials,
the analogues, TPhET 4 and tetraphenyldithiophene 20 displayed
the highest oxidation potentials. It seems that the presence of four
phenyl groups at the peripheries do not help easy oxidation, as
well as the presence of thiophene rings, since all the molecules
having diphenylthiophene showed higher oxidation potentials, i.e.,
19, 20 and 22. On the other hand, the compounds having diphe-
nyldithiindihydroxyl and diphenyldithiindiMEM groups 13 and 21,
respectively, join the lowest oxidation potential group compared
with ET 1. As these ET analogues showed lower oxidation poten-
tials, they were compared with similar molecules having dithiins
with one aryl group such as phenyl 34, 4-BrPh 35 and 4-MeOPh
36. Contrary to the diphenyldithiindiMEM 13 and diphenyldihy-
droxyl 21, these analogues displayed slightly higher oxidation
potentials except 36 having electron donating methoxy group,
which showed a slightly lower oxidation potential than ET. In-
terestingly, 26 having an ethylene peripheral on one side and
a phenyldithiin on the other side showed higher oxidation po-
tentials, the dihydroxyl 37,18b on the other side displayed lower
oxidation potential compared with ET.
Considering the CV results discussed above, the ET analogues
having diphenyldithiin or phenyldithiin rings and dithiomethyl
groups, 16 and 27, respectively, have lower oxidation potentials as
well as the analogues having diphenyldithiin rings and hydroxyl
and MEM groups. Contrarily, having two diphenyldithiin rings put
Figure 4. UV–vis spectroelectrochemistry of ET
TBABF4). Oxidation on a platinum grid.
1
(1.0ꢁ10ꢂ3 M) in CH2Cl2 (0.1 M
Table 2
In ca. 1 mM AcCN solutions, NaClO4 (0.1 M) versus Ag/AgCl, 100 mV sꢂ1
E1 (V)
E21/2 (V)
1/2
1
4
0.46
0.72
0.44
0.36
0.60
0.72
0.41
0.57
0.66
0.49
0.49
0.50
0.42
0.42
0.71
1.03
0.70
0.59
0.84
1.06
0.63
0.80
0.96
0.63
0.74
0.76
0.70
0.70
13
16
19
20
21
22
26
27
34
35
36
37
Figure 5. UV–vis spectroelectrochemistry of fully unsaturated tetraphenyl ET (TPhET)
4 (1.0ꢁ10ꢂ3 M) in CH2Cl2 (0.1 M TBABF4). Oxidation on a platinum grid.

10586
E. Ertas et al. / Tetrahedron 64 (2008) 10581–10589
On gradual increase of potential, the absorption bands of ET at
d
7.14–7.30 (20H, m); 13C NMR (CDCl3)
129.6 (C-t), 134.2 (C-q), 135.3 (C-q), 136.8 (C-q); UV (CH3CN, nm)
237, 296, 338; HRMS (EI) calculated for
34H20S8 Mþ m/z
d 128.4 (C-t), 128.8 (C-t),
321 and 347 nm started to go down as the potential approached to
the first oxidation state, 0.79 V, and three new bands between 388
and 534 nm, 534 and 629 nm and 719 and 1100 nm emerged due to
C
683.933075, found 683.932946. Anal. Calcd for C34H20S8: C, 59.65;
H, 2.92. Found: C, 60.03; H, 2.83.
ꢃ
the formation of cation radical 1þ , forming an isobestic point at
388 nm (Fig. 4). When the potential reached to the second oxida-
tion state, 1.15 V, a new band at 266 nm, possibly due to the for-
mation of the dication 12þ, started to appear. Unfortunately, only
the emergence of the new band could be observed as the pre-
cipitation of the material in the cell took place, so the behaviour of
ET at higher potentials could not be obtained.
3.3. 5,6-Diphenyl-[1,3]dithiolo[4,5-b][1,4]dithiine-2-thione 5
A mixture of 8 (6 g, 10 mmol) and P4S10 (5 g, 11.5 mmol) was
refluxed in dry toluene (100 mL) under a N2 atmosphere and in
dark until the starting material was consumed, which took nearly
3 h. The solvent was then evaporated under reduced pressure and
the residue was separated by column chromatography, eluting with
hexane/CH2Cl2 (3:1) to give the title compound 5 (brown powder,
2.4 g, 65%), 10 (brown powder, 0.7 g, 20%) and 9 (trace) as first,
second and third fractions, respectively. Compound 5. Mp 113–
Although the neutral TPhET showed almost similar absorption
bands with the neutral ET, its bands at 300 and 339 nm appeared
with lower intensities (Fig. 5). Similarly, on gradual increase of
potential, three new bands between 372 and 517 nm, 517 and
631 nm and a third band between 725 and 1069 nm appeared as
the potential approached to the first oxidation potential, 0.86 V. On
contrary to ET, while the band at 241 nm showed a small decrease,
the band at 339 nm went down completely and the band at 300 nm
remained constant. An isobestic point at 372 nm formed. As the
second oxidation state, 1.15 V, was approached a new band at
270 nm started to appear and reached maximum at the second
oxidation potential. No precipitation was observed and no change
of the bands emerged during the first oxidation state. It is not clear
114 ꢀC. 1H NMR (CDCl3)
d
7.09–7.34 (10H, m); 13C NMR (CDCl3)
d
128.6 (C-t), 128.7 (C-t), 129.5 (C-t), 130 (C-q), 134.7 (C-q), 136.2 (C-
q), 213.9 (C]S); IR (KBr, cmꢂ1) 1080 (C]S); UV (CH3CN, nm) 392;
HRMS (EI) calculated for C17H10S5 Mþ m/z 373.938609, found
373.9397. Anal. Calcd for C17H10S5: C, 54.54; H, 2.67. Found: C,
54.85; H, 2.29.
3.4. 2-[5-(2-Oxo-1,2-diphenylethylsulfanyl)-2-thioxo-1,3-
dithiol-4-ylsulfanyl]-1,2-diphenyl-1-ethanone 8
ꢃ
if the bands belong to the cation radical 1þ could remain un-
changed as the second oxidation state of ET is approached.
TPhET shows almost similar spectroelectrochemical behaviour
with ET with the exception that ET displays stronger absorption
peaks in neutral and oxidation states. The advantage TPhET has is
that it does not precipitate at the second oxidation potential.
In conclusion, synthesis of ET analogues incorporating combi-
nations of dithiin and thiophene rings and dihydroxyl groups
has been achieved, employing a 1,8-diketone ring formation re-
action. To our best knowledge, for the first time, a spectroelec-
trochemical comparison of ET with its fully unsaturated analogue
has been performed, which showed that both have a comparable
spectroelectrochemistry.
To the solution of dianion 6 (5 g, 20 mmol) in dry THF (50 mL)
under a N2 atmosphere and in an ice bath was added a solution of
desyl chloride 7 (9.5 g, 40 mmol) in dry THF (30 mL) dropwise from
a dropping funnel, and the mixture was stirred for 3 h at room
temperature. The yellow precipitate was filtered, washed with cold
ethanol and dried to give the title compound 8, which was used for
the next step without further purification (9.9 g, 85%). Mp 158–
159 ꢀC. 1H NMR (CDCl3)
d
7.95 (2H, d, J¼8.1 Hz, Ph), 7.86 (2H, d,
J¼7.0 Hz, Ph), 7.20–7.58 (16H, m, Ph), 6.09 (1H, s), 5.85 (1H, s); EIMS
m/z 586.9 (Mþþ1). Anal. Calcd for C31H22O2S5: C, 63.48; H, 3.75.
Found: C, 63.10; H, 3.92.
The CV measurements indicated that as TPhET 4 has the higher
oxidation potentials, functionalization of ET with the combinations
of dithiin ring and dimethylthio, and dithiin ring and dihydroxyl
help to lower the oxidation potentials. It would appear that the
presence of the dithiin ring on its own, as in 26, does not lower the
oxidation potentials. On the other hand, the presence of dihydroxy
groups alone help to lower the oxidation potentials of ET.
3.5. 5-Benzyl-5-phenyl-[1,3]dithiolo[4,5-d][1,3]dithiole-2-
thione 9
A mixture of 8 (3 g, 5 mmol) and P4S10 (2.5 g, 5.6 mmol) was
refluxed in dry toluene (50 mL) under a N2 atmosphere until the
starting material was consumed, which took nearly 3 h. The solvent
was then evaporated under reduced pressure and the residue was
separated by column chromatography, eluting with hexane/CH2Cl2
(2:1) to give the title compound 9 as a brown powder (0.17 g, 25%)
and 10 as a brown powder (0.5 g, 30%) as first and second fractions,
3. Experimental section
3.1. General
respectively. Compound 9. Mp 128–129 ꢀC. 1H NMR (CDCl3)
d 7.13–
Melting points are uncorrected. NMR spectra were recorded in
CDCl3 with tetramethylsilane as the internal standard for 1H
(250 MHz) or solvent as the internal standard for 13C (67.8 MHz)
unless otherwise stated. Mass spectra were recorded at an ionizing
voltage of 70 eV. Chromatography was performed on flash silica gel
(Merck) and TLC was carried out on 0.2 mm silica gel plates. All
reagents and solvents were commercial grade (Aldrich) and puri-
fied according to established convention.
7.26 (8H, m), 6.95 (2H, d, J¼7 Hz), 3.76 (2H, s); 13C NMR (CDCl3)
d
50.75 (CH2), 86.34 (C-t), 127.0, 127.6, 127.8, 128.5, 128.85, 129.6,
134.5 (C-q), 139.5 (C-q), 205 (C]S); IR (KBr, cmꢂ1) 1080 (C]S); UV
(CH3CN, nm) 426; EIMS m/z 375.5 (Mþ). Anal. Calcd for C17H12S5: C,
54.25; H, 3.19. Found: C, 53.90; H, 2.82. 5,6-Diphenylthieno[3,2-
d][1,3]dithiole-2-thione 10.15b Mp: 156–157 ꢀC. 1H NMR (CDCl3)
d
7.25–7.37 (10H, m), 13C NMR (CDCl3) 128.5, 128.6, 128.8, 129, 129.1,
129.6, 132.6, 133.9, 140, 143.9, 213 (C]S); IR (KBr, cmꢂ1) 1080
(C]S); UV (CH3CN, nm) 398; EIMS m/z 342 (Mþ). Anal. Calcd for
3.2. 5,50-6,60-Tetraphenyl-2,20bi([1,3]dithiolo[4,5-b]
C17H10S4: C, 59.64; H, 2.92. Found: C, 60.10; H, 2.59.
[1,4]dithiinylidene) 4
3.6. 5,6-Diphenyl-[1,3]dithiolo[4,5-b][1,4]dithiin-2-one 11
Compound 1116 (1 g, 2.8 mmol) was heated in freshly distilled
(EtO)3P (20 mL) under a N2 atmosphere at 110 ꢀC for 3 h. (EtO)3P
was then evaporated under reduced pressure. The residue was
recrystallized from methanol to give the title compound 4 (0.86 g,
90%) as a yellow powder. Mp 248–250 ꢀC. 1H NMR (CDCl3)
A mixture of 5 (2 g, 5.5 mmol) dissolved in CHCl3 (20 mL),
mercuric acetate (5 g, 15 mmol) and glacial acetic acid (20 mL) was
stirred at room temperature for 1 h. The mixture was filtered
through Celite and the filtrate was extracted with sodium

E. Ertas et al. / Tetrahedron 64 (2008) 10581–10589
10587
carbonate solution (2ꢁ50 mL) and water (2ꢁ50 mL). The organic
layer was dried over sodium sulfate, filtered and the solvent was
evaporated under reduced pressure to give the title compound 11
(1.6 g, 80%) as a light yellow powder. Mp 116–118 ꢀC. 1H NMR
distilled (EtO)3P (20 mL) under a N2 atmosphere at 110 ꢀC for 3 h.
(EtO)3P was distilled off and the residue was separated by column
chromatography eluting with hexane/ethyl acetate (1:1). The sec-
ond fraction gave the title compound 19 (0.17 g, 30%) as an orange
(CDCl3)
d
7.12–7.20 (10H, m); 13C NMR (CDCl3)
d
120.5 (C-q), 128.37,
powder. Mp 182–184 ꢀC. 1H NMR (CDCl3)
d
7.26–7.32 (10H, m), 4.50
(4H, s), 3.73 (4H, s), 3.66 (4H, t), 3.63 (4H, t), 3.39 (6H, s), 2.76 (4H,
s); 13C NMR (CDCl3)
29.7 (C-t), 37.0 (C-t), 44.3 (S–CH2), 59.1 (O–
128.5, 130.6, 134.55 (C-q), 136.5 (C-q), 192 (C]O); IR (KBr, cmꢂ1
)
1690 (C]O); UV (CH3CN, nm) 3010; HRMS (EI) calculated for
d
C
C
17H10S4O Mþ m/z 357.96145, found 357.96915. Anal. Calcd for
17H10OS4: C, 56.98; H, 2.79. Found: C, 57.31; H, 2.52.
CH3), 67.0 (O–CH2, br), 69.7 (O–CH2CH2–O), 71.7 (O–CH2CH2–O),
95.8 (O–CH2–O), 114.6 (C-q), 117.3 (C-q), 122.5 (C-q), 128.3, 128.8,
129.6 (C-q), 135.2 (C-q), 136.8 (C-q); HRMS (EI) calculated for
3.7. 6,6-Bis(2-methoxyethoxymethyl)-6,7-dihydro-2-(5,6-
diphenyl-[1,3]dithiolo[4,5-b][1,4]dithiin-2-ylidene)-5H-
[1,3]dithiolo[4,5-b][1,4]dithiepine 13
C
C
33H36O6S7 Mþ m/z 752.05569, found. 752.05482. Anal. Calcd for
33H36O6S7: C, 52.65; H, 4.78. Found: C, 52.88; H, 4.45.
A mixture of oxo compound 11 (0.5 g, 1.4 mmol) and MEM
protected oxo derivative 1218b (0.65 g, 1.4 mmol) was heated in
freshly distilled (EtO)3P (20 mL) under a N2 atmosphere at 110 ꢀC
for 3 h. (EtO)3P was distilled off and the residue was separated by
column chromatography eluting with hexane/ethyl acetate (1:1).
The second fraction gave the title compound 13 (0.16 g, 30%) as an
3.11. 2-(5,6-Diphenyl[1,3]ditholo[4,5-b][1,4]dithiin-2-yliden)-
6-hydroxymethyl-6,7-dihydro-5H-[1,3]dithiolo[4,5-
b][1,4]dithiepin-6-ylmethanol 21
To a solution of 13 (0.25 g, 0.32 mmol) in THF (10 mL) was added
dropwise 20% aq HCl (5 mL). The mixture was stirred at room
temperature for 2 days. It was then neutralized with solid sodium
carbonate. The THF layer was decanted and the remaining material
was extracted with THF (30 mL). The combined THF solutions were
dried over magnesium sulfate, filtered and the solvent was evap-
orated under reduced pressure to give the title compound 21
(0.15 g, 75%) as an orange powder. Mp 185–187 ꢀC. 1H NMR (CDCl3)
orange powder. Mp 185–187 ꢀC. 1H NMR (CDCl3)
m), 4.7 (4H, s), 3.72 (4H, s), 3.61–3.64 (4H, m), 3.51–3.54 (4H, m),
3.38 (6H, s), 2.75 (4H, s); 13C NMR (CDCl3)
29.7 (C-t), 37.0 (C-t),
d 7.12–7.22 (10H,
d
44.2 (S–CH2), 59.0 (O–CH3), 64.5 (O–CH2, br), 69.6 (O–CH2CH2–O),
71.7 (O–CH2CH2–O), 95.8 (O–CH2–O), 122.5 (C-q), 128.3, 128.6,
128.8, 129.6 (C-q), 135.2 (C-q), 136.8 (C-q); EIMS m/z 785.3 (Mþ).
Anal. Calcd for C33H36O6S8: C, 50.51; H, 4.59. Found: C, 50.25; H,
4.70.
d
7.00 (10H, s), 5.03 (2H, s), 3.82 (4H, br s), 2.29 (4H, s); 13C NMR
(CDCl3) d 36.8 (C-q), 44.3 (S–CH2), 64.5 (O–CH2), 122.5, 125.5, 128.3,
129.5, 132.0, 135.3, 136.8, 135.7; EIMS m/z 607.8 (Mþ). Anal. Calcd
3.8. 2-(4,5-Bis(methylthio)-1,3-dithiol-2-ylidene)-5,6-
for C25H20O2S8: C, 49.34; H, 3.28. Found: C, 49.11; H, 3.52.
diphenyl-[1,3]dithiolo[4,5-b][1,4]dithiine 16
A mixture of oxo compounds 11 (1 g, 2.8 mmol) and 15 (0.63 g,
2.8 mmol) was heated in freshly distilled (EtO)3P (20 mL) under
a N2 atmosphere at 110 ꢀC for 3 h. (EtO)3P was distilled off and the
residue was separated by column chromatography eluting with
hexane/CH2Cl2 (25:1). The third fraction gave the title compound
16 (0.26 g, 35%) as a brown powder. Mp 165–168 ꢀC. 1H NMR
3.12. 2-(5,6-Diphenylthieno[2,3-d][1,3]dithiol-2-yliden)-6-
hydroxymethyl-6,7-dihydro-5H-[1,3]dithiolo[4,5-b]
[1,4]dithiepin-6-ylmethanol 22
To a solution of 19 (0.25 g, 0.33 mmol) in THF (10 mL) was added
dropwise 20% aq HCl (5 mL). The mixture was stirred at room
temperature for 2 days. It was then neutralized with solid sodium
carbonate. The THF layer was decanted and the remaining material
was extracted with THF (30 mL). The combined THF solutions were
dried over magnesium sulfate, filtered and the solvent was evap-
orated under reduced pressure to give the title compound 22
(0.14 g, 75%) as an orange powder. Mp 177–179 ꢀC. 1H NMR (CDCl3)
(CDCl3)
(CH3),122.5 (C-q),128.3,128.6,128.8,129.5 (C-q),129.6 (C-q),135.21
(C-q), 136.8 (C-q); HRMS (EI) calculated for
22H16S8 Mþ m/z
d d 19.2
7.09–7.22 (10H, m), 2.42 (6H, s); 13C NMR (CDCl3)
C
535.90177, found 535.89645. Anal. Calcd for C22H16S8: C, 49.25; H,
2.98. Found: C, 49.12; H, 2.72.
3.9. 5,6-Diphenylthieno[3,2-d][1,3]dithiol-2-one 18
d
7.05 (10H, s), 3.9 (4H, br s), 2.70 (4H, s); EIMS m/z 574.9 (Mþ). Anal.
Calcd for C25H20O2S7: C, 52.08; H, 3.47. Found: C, 52.30; H, 3.15.
A mixture of 10 (2 g, 5.84 mmol) dissolved in CHCl3 (20 mL),
mercuric acetate (5 g, 15 mmol) and glacial acetic acid (20 mL)
was stirred at room temperature for 1 h. The mixture was fil-
tered through Celite and the filtrate was extracted with aq so-
dium carbonate solution (2ꢁ50 mL) and water (2ꢁ50 mL). The
organic layer was dried over sodium sulfate, filtered and the
solvent was evaporated under reduced pressure to give the title
compound 18 (1.33 g, 70%) as a white powder. Mp 162–163 ꢀC.
3.13. 6,6-Bis(2-methoxyethoxymethyl)-2-(5-phenyl[1,3]
dithiolo[4,5-b][1,4]dithiin-2-ylidene)-6,7-dihydro-5H-2-
(5,6-diphenyl-[1,3]dithiolo[4,5-b][1,4]dithiin-2-ylidene)-
5H-[1,3]dithiolo[4,5-b][1,4]dithiepin 33 (R[H)
A mixture of oxo compounds 31 (0.30 g, 1.06 mmol) and 12
(0.48 g, 1.04 mmol) was heated in freshly distilled (EtO)3P (20 mL)
under a N2 atmosphere at 110 ꢀC for 3 h. (EtO)3P was distilled off
and the residue was separated by column chromatography eluting
with initially hexane/CH2Cl2 (3:1) mixture to separate 32 and then
with the mixture of ethylacetate/hexane (3:1) to separate 33 and 14
as the second and third fractions, respectively. Compound 33 (R¼H)
1H NMR (CDCl3)
d d 121.5
7.17–7.36 (10H, m); 13C NMR (CDCl3)
(C-q), 128.31, 128.7, 129.1, 129.2, 129.6, 132.6, 134.55 (C-q), 140.0
(C-q), 196.0 (C]O); IR (KBr, cmꢂ1) 1690 (C]O); EIMS m/z 326.5
(Mþ). Anal. Calcd for C17H10OS3: C, 62.57; H, 3.06. Found: C,
62.20; H, 2.81.
3.10. 2-(5,6-Diphenylthieno[2,3-d][1,3]dithiol-2-yliden)-6,6-
di(2-methoxyethoxymethoxymethyl)-6,7-dihydro-5H-
[1,3]dithiolo[4,5-b][1,4]dithiepine 19
(0.20 g, 27%) yellow powder. 1H NMR (CDCl3)
d 7.44–7.50 (2H, m,
Ph), 7.25–7.29 (3H, m, Ph), 6.59 (1H, s, ]CH), 4.69 (4H, s, 2ꢁOCH2O),
3.52–3.58 (8H, m, 4ꢁOCH2), 3.45–3.50 (4H, m, 2ꢁOCH2CH2O), 3.39
(6H, s, 2ꢁOCH3), 2.75 (4H, s, 2ꢁSCH2); HRMS (EI) calculated for
A mixture of oxo compound 18 (0.5 g, 1.5 mmol) and MEM
protected oxo derivative 12 (0.70 g, 1.5 mmol) was heated in freshly
C
27H32O6S8 Mþ m/z 709.0235, found 709.0238.
The following were similarly produced.

10588
E. Ertas et al. / Tetrahedron 64 (2008) 10581–10589
3.14. 6,6-Bis(2-methoxyethoxymethyl)-2-(5-(4-bromo
phenyl)[1,3]dithiolo[4,5-b][1,4]dithiin-2-ylidene)-6,7-
dihydro-5H-2-(5,6-diphenyl-[1,3]dithiolo[4,5-b][1,4]dithiin-2-
ylidene)-5H-[1,3]dithiolo[4,5-b][1,4]dithiepin 33 (R[Br)
67.5 MHz) d 142.5 (CH]), 130.0 (CH]), 129.3 (C]), 128.7 (CH]),
122.6 (CH]), 118.0 (CH]), 117.2 (C]), 115.0 (C]), 64.8 (br, COH),
55.6 (OCH3), 46.2 (CS), 37.5 (C); HRMS calculated for C20H18O3S8 Mþ
m/z 561.9008, found 561.9021. Anal. Calcd for C20H18O3S8: C, 42.70;
H, 3.20. Found: C, 42.80; H, 3.29.
Column chromatography eluting with ethylacetate/hexane (3:1)
gave the self-coupled 32 as the first fraction, the cross-coupled 33
as the second fraction and the cross-coupled 14 as the third frac-
tion. Compound 33 (R¼Br) (29%) yellow powder. 1H NMR (CDCl3)
3.19. X-ray structure determination
Specimen of suitable quality and size of 13 was mounted on
a fibreglass and used for intensity data collection. The X-ray dif-
fraction data of 13 was collected using a CAD4 single crystal dif-
d
7.46 (2H, d, J¼8.6 Hz, Ph), 7.37 (2H, d, J¼8.6 Hz, Ph), 6.59 (1H, s,
]CH), 4.67 (4H, s, 2ꢁOCH2O), 3.63–3.58 (8H, m, 4ꢁOCH2), 3.55–
3.51 (4H, m, 2ꢁOCH2), 3.37 (6H, s, 2ꢁOCH3), 2.73 (4H, s, 2ꢁSCH2);
FABMS m/z 788 (Mþþ1).
fractometer. Graphite monochromated Mo
Ka
radiation
(l¼0.71073 Å) was generated at 50 kV and 40 mA. The data sets
were corrected for Lorentz and polarization effects. Psi-scan ab-
sorption correction was applied for 13. The structure was solved by
direct methods program SHELXS-9723 and refined by the full-ma-
trix least-squares method based on F2 using SHELXL-97.24 The
structure solution revealed disorder in the side chains connected to
the C19 atom. To prevent abnormal bond lengths and angles, geo-
metric restraints were applied to the neighbouring atomic dis-
tances. Two components of the disordered atoms were located in
difference maps. The disordered atoms were refined isotropically
and the occupation factors converged at 0.702(12) and 0.298(12)
for each component. The hydrogen atoms were positioned geo-
metrically and refined using a riding model. The calculations were
carried out with the PLATON25 and PARST97.26
3.15. 6,6-Bis(2-methoxyethoxymethyl)-2-(5-(4-methoxy
phenyl)[1,3]dithiolo[4,5-b][1,4]dithiin-2-ylidene)-6,7-
dihydro-5H-2-(5,6-diphenyl-[1,3]dithiolo[4,5-b]
[1,4]dithiin-2-ylidene)-5H-[1,3]dithiolo[4,5-b]
[1,4]dithiepin 33 (R[OCH3)
Column chromatography eluting with ethylacetate/hexane (3:1)
gave the self-coupled 32 as the first fraction, the cross-coupled 33
(R¼OCH3) as the second fraction and the cross-coupled 14 as the
third fraction.
Compound 33 (R¼OCH3) (40%) yellow powder. 1H NMR (CDCl3)
d
7.47 (2H, d, J¼8.4 Hz, Ph), 6.87 (2H, d, J¼8.4 Hz, Ph), 6.46 (1H, s,
]CH), 4.70 (4H, s, 2ꢁOCH2O), 3.71 (3H, s, OCH3), 3.63–3.58 (8H, m,
4ꢁOCH2), 3.55–3.51 (4H, m, 2ꢁOCH2), 3.36 (6H, s, 2ꢁOCH3), 2.72
(4H, s, 2ꢁSCH2); FABMS m/z 739 (Mþþ1).
3.20. Crystal data and refinement parameters
The following were similarly produced as 21.
C
33H10O6S8, Triclinic, P1, a¼9.375(2) Å, b¼13.122(3) Å, c¼15.
918(5) Å,
a
¼72.06(2)ꢀ,
b
¼86.80(3)ꢀ,
g
¼83.294(17)ꢀ, volume¼184
3.16. [6-(Hydroxymethyl)-2-(5-phenyl[1,3]dithiolo[4,5-
b][1,4]dithiin-2-ylidene)-6,7-dihydro-5H-[1,3]dithiolo[4,5-
b][1,4]dithiepin-6-yl]methanol 34
9.8(8) Å3, Z¼2, Dc¼1.363 Mg mꢂ3
,
m
¼0.523 mmꢂ1
,
qmax¼26.3ꢀ,
7759 measured and 3026 unique (Rint¼0.0578) reflections, R1
(obsd)¼0.1001 and wR2 (all data)¼0.357, rmax
/rmin¼1.901/
ꢂ1.032 e Åꢂ3. CCDC reference number: 266306.
Column chromatography eluting with ethylacetate/hexane (3:1)
gave the title compound 34 (43%). Mp 182–184 ꢀC. Yellow powder.
References and notes
1H NMR (DMSO-d6)
d 7.62–7.57 (2H, m, Ph), 7.43–7.40 (3H, m, Ph),
7.21 (1H, s, ]CH), 4.61 (2H, br, OH), 3.55 (4H, d, J¼5.2 Hz, 2ꢁOCH2),
1. Williams, J. M.; Ewge, T. J.; Wang, H. H.; Beno, M. A.; Copps, P. T.; Hall, L. N.;
Carlson, K. D.; Crabtree, G. W. Inorg. Chem. 1984, 23, 2558–2560.
2. (a) Williams, J. M.; Ferrano, J. R.; Thorn, R. J.; Carlson, K. D.; Geiser, U.; Wang, H. H.;
Kini, A. M.; Whangbo, M.-H. Organic Superconductors (Including Fullerenes);
Prentice Hall: Englewood Cliffs, NJ, 1992; (b) Bryce, M. R. J. Mater. Chem. 1995, 5,
1481–1496; (c) Bryce, M. R. J. Mater. Chem. 2000, 10, 589–598; (d) Saito, G.;
Yoshida, Y. Bull. Chem. Soc. Jpn. 2007, 80, 1–137.
3. Kini, A. M.; Geiser, U.; Wang, H. H.; Carlson, K. D.; Williams, J. M.; Kwok, W. K.;
Vandervoort, K. G.; Thompson, J. E.; Stupka, D. L.; Jung, D.; Whangbo, M. H.
Inorg. Chem. 1990, 29, 2555–2557.
2.72 (4H, s, 2ꢁSCH2); FABMS m/z 532 (Mþ). Anal. Calcd for
C
19H16O2S8: C, 42.85; H, 3.00. Found: C, 42.83; H, 2.98.
3.17. [2-[5-(4-Bromophenyl)[1,3]dithiolo[4,5-b][1,4]dithiin-2-
ylidene]-6-(hydroxymethyl)-6,7-dihydro-5H-[1,3]dithiolo[4,5-
b][1,4]dithiepin-6-yl]methanol 35
4. (a) Griffiths, J.-P.; Nie, H.; Brown, R. J.; Day, P.; Wallis, J. D. Org. Biomol. Chem.
2005, 3, 2155–2166; (b) Wallis, J. D.; Griffiths, J. P. J. Mater. Chem. 2005, 15,
347–365.
5. Bryce, M. R.; Green, A.; Moore, A. J.; Perepichka, D. F.; Batsanov, A. S.; Howard,
J. A. K.; Ledoux-Rak, I.; Gonza`lez, M.; Martin, N.; Segura, J. L.; Garin, J.; Orduna,
J.; Alcala`, R.; Villacampa, B. Eur. J. Org. Chem. 2001, 1927–1935.
Column chromatography eluting with ethylacetate/hexane (3:1)
gave the title compound 35 (35%). Mp 130–131 ꢀC. Yellow powder.
1H NMR (DMSO-d6)
d
7.62 (2H, d, J¼8.7 Hz, Ph), 7.54 (2H, d,
J¼8.7 Hz, Ph), 7.29 (1H, s, ]CH), 4.61 (2H, br, OH), 3.55 (4H, d,
J¼4.8 Hz, 2ꢁOCH2), 2.75 (4H, s, 2ꢁSCH2); 13C NMR (DMSO-d6)
6. Andreu, R.; Barbera, J.; Garin, J.; Orduna, J.; Serrano, J. L.; Sierra, T.; Leriche, P.;
d
138.5 (CH]), 135.2 (C]), 134.0 (CH]), 132.1 (C]), 129.0 (C]),
´
Salle, M.; Riou, A.; Jubault, M.; Gorgues, A. J. Mater. Chem. 1998, 8, 881–887.
123.0 (CH]), 121.7 (CH]), 62.0 (br, COH), 45.1 (CS), 36.3 (C]);
EIMS m/z 611 (Mþ). Anal. Calcd for C19H15BrO2S8: C, 37.31; H, 2.45.
Found: C, 37.45; H, 2.71.
7. Bryce, M. R.; Devonport, W.; Goldenberg, L. M.; Wang, C. J. Chem. Soc., Chem.
Commun. 1988, 945–951.
8. Christensen, C. A.; Goldenberg, L. M.; Bryce, M. R.; Becher, J. J. Chem. Soc., Chem.
Commun. 1988, 509–510.
9. Christensen, C. A.; Bryce, M. R.; Becher, J. Synthesis 2000, 1695–1704.
10. (a) Huchet, L.; Akoudad, S.; Roncali, J. Adv. Mater. 1998, 10, 541–545; (b) Ska-
bara, P. J.; Roberts, D. M.; Serebryakov, I. M.; Gozalo, C. P. Chem. Commun. 2000,
1005–1006.
11. (a) Damgaard, D.; Nielson, M. B.; Lau, J.; Jensen, K. B.; Zubarev, R.; Levillain, E.;
Becher, J. J. Mater. Chem. 2000, 14, 2249–2258; (b) Nielson, M. B.; Hansen, J. G.;
Becher, J. Eur. J. Chem.1999, 2807–2815; (c) Asakawa, M.; Ashton, P. R.; Balzani, V.;
Credi, A.; Hamers, C.; Mattersteig, G.; Montalti, M.; Shipway, A. N.; Spencer, N.;
Stoddart, J. F.; Tolley, M. S.; Venturi, M.; White, A. J. P.; Williams, D. J. Angew. Chem.,
Int. Ed. 1998, 37, 333–337.
3.18. {6-(Hydroxymethyl)-2-[5-(4-methoxyphenyl)
[1,3]dithiolo[4,5-b][1,4]dithiin-2-ylidene]-
6,7-dihydro-5H-[1,3]dithiolo[4,5-b][1,4]
dithiepin-6-yl}methanol 36
Column chromatography eluting with ethylacetate/hexane (3:1)
gave the title compound 36 (34%). Mp 140–144 ꢀC. Yellow powder.
1H NMR (THF-d8)
Ph), 6.62 (1H, s, ]CH), 4.65 (2H, br, OH), 3.68 (3H, s, OCH3), 3.52
(4H, d, J¼4.8 Hz, 2ꢁOCH2), 2.76 (4H, s, 2ꢁSCH2); 13C NMR (THF-d8,
d
7.40 (2H, d, J¼8.8 Hz, Ph), 6.79 (2H, d, J¼8.8 Hz,
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