New Tetrathiafulvalene Donors with Extended Peripheral Substituents by Addition of Heterocycles: Synthesis, Properties, and Molecular Structures

Article abstract of DOI:10.1021/jo972337y

Syntheses of the bis(heterocycle)-fused bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) derivatives 7 and 8, the heterocycle-fused BEDT-TTF, methylenedithio(ethylenedithio)tetrathiafulvalene (MET), and ethylenedithiotetrathiafulvalene derivatives 9-11, and the 1,3-dioxolane derivative of MET 12a and its analogues 12b-d are described. The heterocycle-fused ketones 17 and 19 with cis ring fusions could be prepared by the BF₃-promoted reaction of tin dithiolate 13 with dihaloheterocycles 15 and 16 in good yields, respectively, and served as key intermediates for the (RO)₃P- and/or Me₃Al-promoted coupling syntheses of these new tetrathiafulvalene donors 7-12. Further, the electrochemical properties of new donors 8-12 by the use of cyclic voltammetry and the molecular structures of 9a, 10a, 11, and 12a by X-ray crystallographic analyses are also reported.

Full text of DOI:10.1021/jo972337y

3952
J . Org. Chem. 1998, 63, 3952-3960
New Tetr a th ia fu lva len e Don or s w ith Exten d ed P er ip h er a l
Su bstitu en ts by Ad d ition of Heter ocycles: Syn th esis, P r op er ties,
a n d Molecu la r Str u ctu r es
J un-ichi Yamada,*,† Satoru Tanaka,† J unko Segawa,† Miho Hamasaki,† Kenji Hagiya,†
Hiroyuki Anzai,† Hiroyuki Nishikawa,‡ Isao Ikemoto,‡ and Koichi Kikuchi‡
Department of Material Science, Faculty of Science, Himeji Institute of Technology, 1475-2 Kanaji,
Kamigori-cho, Ako-gun, Hyogo 678-1297, J apan, and Department of Chemistry, Faculty of Science, Tokyo
Metropolitan University, Hachioji, Tokyo 192-0397, J apan
Received December 31, 1997
Syntheses of the bis(heterocycle)-fused bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) derivatives
7 and 8, the heterocycle-fused BEDT-TTF, methylenedithio(ethylenedithio)tetrathiafulvalene (MET),
and ethylenedithiotetrathiafulvalene derivatives 9-11, and the 1,3-dioxolane derivative of MET
12a and its analogues 12b-d are described. The heterocycle-fused ketones 17 and 19 with cis
ring fusions could be prepared by the BF3-promoted reaction of tin dithiolate 13 with dihalohet-
erocycles 15 and 16 in good yields, respectively, and served as key intermediates for the (RO)3P-
and/or Me3Al-promoted coupling syntheses of these new tetrathiafulvalene donors 7-12. Further,
the electrochemical properties of new donors 8-12 by the use of cyclic voltammetry and the
molecular structures of 9a , 10a , 11, and 12a by X-ray crystallographic analyses are also reported.
In tr od u ction
Ever since the discovery of the first metallic charge-
transfer complex composed of TTF (tetrathiafulvalene,
1, Figure 1) and TCNQ (tetracyanoquinodimethane),1
modifications of the TTF skeleton have received consider-
able attention from synthetic chemists in exploration of
new molecular-based organic metals.2 Among those
modifications known to date, the heterocycle-fused TTF
donors, such as BEDT-TTF [bis(ethylenedithio)tetrathia-
fulvalene, 2], MET [methylenedithio(ethylenedithio)-
tetrathiafulvalene, 3], EDT-TTF (ethylenedithiotetrathia-
fulvalene, 4), and MDT-TTF (methylenedithiotetrathia-
fulvalene, 5), are very attractive π-electron donors be-
cause most of them have produced organic superconduc-
tors.3 In particular, BEDT-TTF (2) has yielded the
largest number of superconducting salts, and it is now
well-known that the additional sulfur atoms accompanied
by fusion of a 1,4-dithiane ring onto both sides of the
prototype TTF molecule play an important part in the
formation of two-dimensional conducting S‚‚‚S networks
in the BEDT-TTF-based superconductors.4 Therefore,
one synthetic method for the construction of new TTF
donors leading to conducting salts with enhanced dimen-
sionality of conduction might be the addition of another
† Himeji Institute of Technology.
‡ Tokyo Metropolitan University.
(1) Ferraris, J . P.; Cowan, D. O.; Walatka, V.; Perlstein, J . H. J .
Am. Chem. Soc. 1973, 95, 948-949.
(2) For recent reviews, see: (a) Otsubo, T.; Aso, Y.; Takimiya, K.
Adv. Mater. 1996, 8, 203-211. (b) Bryce, M. R. J . Mater. Chem. 1995,
5, 1481-1496. (c) Gar´ın, J . Adv. Heterocycl. Chem. 1995, 62, 249-
304. (d) Adam, M.; Mu¨llen, K. Adv. Mater. 1994, 6, 439-459. (e)
Hansen, T. K.; Becher, J . Adv. Mater. 1993, 6, 439-459. (f) Cowan. D.
O.; Mccullough, R.; Bailey, A.; Lerstrup, K.; Talham, D.; Herr, D.; Mays,
M. Phosphorus, Sulfur, Silicon 1992, 67, 277-294. (g) Bryce, M. R.
Chem. Soc. Rev. 1991, 20, 355-390. (h) Schukat, G.; Richter, A. M.;
Fangha¨nel, E. Sulfur Rep. 1987, 7, 155-240.
(3) (a) Tajima, H.; Inokuchi, M.; Kobayashi, A.; Ohta, T.; Kato, R.;
Kobayashi, H.; Kuroda, H. Chem. Lett. 1993, 1235-1238. (b) Underhill,
A. E. J . Mater. Chem. 1992, 2, 1-11. (c) Williams, J . M.; Schultz, A.
J .; Geiser, U.; Carlson, K. D.; Kini, A. M.; Wang, H. H.; Kwok, W.-K.;
Whangbo, M.-H.; Schirber, J . E. Science 1991, 252, 1501-1508.
F igu r e 1.
heterocycle onto the existing one or both outer rings in
the known heterocycle-fused TTF derivatives, and to this
end, the bis(dioxane)-fused BEDT-TTF derivative [BDDT-
TTF (6)] has been already synthesized.5 Further appear-
ance of such a π-electron donor bearing extended sub-
S0022-3263(97)02337-2 CCC: $15.00 © 1998 American Chemical Society
Published on Web 05/27/1998

New TTF Donors with Extended Peripheral Substituents
J . Org. Chem., Vol. 63, No. 12, 1998 3953
stituents by the σ-bond framework on the periphery of
the TTF core would be of interest in preparation of new
molecular-based conductors.6
Meanwhile, we have found that the combination of
organotin dichalcogenolates with Me3Al as a Lewis acid
is versatile for the formation of the internal carbon-
carbon double bonds of unsymmetrical TTF derivatives,
DSDTF (diselenadithiafulvalene) derivatives, and TTF-
fused donors.7 Our next search for the synthetic pos-
sibilities presented by the combination of dichalcogenos-
tannanes and a Lewis acid involved the use of the BF3-
promoted reaction of organotin dithiolates with 1,2-
dihaloheterocycles in order to develop a synthetic route
to new TTF donors with extended periphery by addition
of several heterocycles.8 We now describe a detailed
study of the syntheses of new bis(heterocycle)-fused
BEDT-TTF derivatives 7 and 8 and the heterocycle-fused
BEDT-TTF, MET, and EDT-TTF derivatives 9-11, as
well as the electrochemical characterization of 8-11 and
X-ray crystallographic analyses of 9a , 10a , and 11.
Further, in the course of this work, we found that the
synthesis of the 1,3-dioxolane derivative of MET 12a and
its analogues 12b-d can be accomplished via the Me3Al-
mediated rearrangement.9 We also present the synthesis
and electrochemical properties of these new donors
together with an X-ray structural analysis of 12a .
F igu r e 2. Molecular structure of 17.
Sch em e 1
Sch em e 2
Resu lts a n d Discu ssion
P r ep a r a t ion of P r ecu r sor s for Tw o Cou p lin g
Syn th eses. Synthetic routes to our final products in this
study are based on two coupling reactions, viz., the
(RO)3P-promoted coupling reaction between 1,3-dithiole-
2-chalcogenones (eq 1, Scheme 1) and the Me3Al-
promoted coupling reaction7 between organotin dithi-
olates and esters (eq 2). As shown in Scheme 2,
(4) (a) Geiser, U.; Schlueter, J . A.; Wang, H. H.; Kini, A. M.;
Williams, J . M.; Sche, P. P.; Zakowicz, H. I.; VanZile, M. L.; Dudek, J .
D. J . Am. Chem. Soc. 1996, 118, 9996-9997. (b) Kurmoo, M.; Graham,
A. W.; Day, P.; Coles, S. J .; Hursthouse, M. B.; Caulfield, J . L.;
Singleton, J .; Pratt, F. L.; Hayes, W.; Ducasse, L.; Guionneau, P. J .
Am. Chem. Soc. 1995, 117, 12209-12217. (c) Williams, J . M.; Ferraro,
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. (d) Ishiguro, T.; Yamaji, K.
Organic Superconductors; Springer-Verlag: Berlin, Heidelberg, 1990.
(5) (a) Kotov, A. I.; Faulmann, C.; Cassoux, P.; Yagubskii, E. B. J .
Org. Chem. 1994, 59, 2626-2629. For the alternative synthesis of
BDDT-TTF, see: (b) Kini, A. M.; Geiser, U.; Wang, H.-H.; Lykke, K.
R.; Williams, J . M.; Campana, C. F. J . Mater. Chem. 1995, 5, 1647-
1652.
preparation of the chalcogenones and the tin-masked
dithiolates as reactants used for these coupling reactions
was effected via the BF3-promoted reactions of tin dithi-
olates 13 and 14 with dihalides 15 and 16 as key steps.
Tin dithiolate 13 was accessible by our reported
procedure,7c and 14 could be obtained by treatment of
(Bu4N)2[Zn(dmit)2] (dmit ) 4,5-dimercapto-1,3-dithiole-
2-thione) with Cl2SnBu2 in THF at room temperature
(92% yield). These tin dithiolates 13 and 14 reacted
smoothly with commercially available trans-2,3-dichloro-
1,4-dioxane (15) in the presence of BF3‚OEt2 to give
ketone 17 and thione 18 as single stereoisomers in 91%
and 63% yields, respectively. An X-ray crystallographic
analysis of 17 confirmed the cis stereochemistry for two
methine protons (Figure 2). Also, the methine protons
of 18 are presumably in the cis position, since reaction
of 18 with Hg(OAc)2 in THF-AcOH resulted in the
production of the ketone 17 (81% yield). The exclusively
cis stereoselectivity in these reactions appears to be due
(6) Recently, synthesis of the bis(oxathiane)-fused BEDT-TTF de-
rivative has been reported, see: Hellberg, J .; Balodis, K.; Moge, M.;
Korall, P.; von Schu¨tz, J .-U. J . Mater. Chem. 1997, 7, 31-34.
(7) (a) Yamada, J .; Akashi, N.; Anzai, H.; Tamura, M.; Nishio, Y.;
Kajita, K. Mol. Cryst. Liq. Cryst. 1997, 296, 53-59. (b) Yamada, J .;
Mishima, S.; Akashi, N.; Satoki, S.; Anzai, H. Synth. Metals 1997, 86,
1823-1824. (c) Yamada, J .; Mishima, S.; Anzai, H.; Tamura, M.;
Nishio, Y.; Kajita, K.; Sato, T.; Nishikawa, H.; Ikemoto, I.; Kikuchi,
K. J . Chem. Soc., Chem. Commun. 1996, 2517-2518. (d) Yamada, J .;
Satoki, S.; Anzai, H.; Hagiya, K.; Tamura, M.; Nishio, Y.; Kajita, K.;
Watanabe, E.; Konno, M.; Sato, T.; Nishikawa, H.; Kikuchi, K. J . Chem.
Soc., Chem. Commun. 1996, 1955-1956. (e) Yamada, J .; Satoki, S.;
Mishima, S.; Akashi, N. Takahashi, K.; Masuda, N.; Nishimoto, Y.;
Takasaki, S.; Anzai, H. J . Org. Chem. 1996, 61, 3986-3995. (f)
Yamada, J .; Takasaki, S.; Kobayashi, M.; Anzai, H.; Tajima, N.;
Tamura, M.; Nishio, Y.; Kajita, K. Chem. Lett. 1995, 1069-1070. (g)
Yamada, J .; Amano, T.; Takasaki, S.; Nakanishi, R.; Matsumoto, K.;
Satoki, S.; Anzai, H. J . Am. Chem. Soc. 1995, 117, 1149-1150.
(8) For a preliminary communication, see: Yamada, J .; Nishimoto,
Y.; Tanaka, S.; Nakanishi, R.; Hagiya, K.; Anzai, H. Tetrahedron Lett.
1995, 36, 9509-9512.
(9) For a communication, see: Yamada, J .; Hamasaki, M.; J inih,
O.; Tanaka, S.; Hagiya, K.; Anzai, H. Tetrahedron Lett. 1997, 38, 3439-
3442.

3954 J . Org. Chem., Vol. 63, No. 12, 1998
Yamada et al.
F igu r e 4.
F igu r e 3. Molecular structure of 19.
(RO)3P-promoted coupling reaction of ketone 17 with
thiones 28-30 was examined to synthesize the dioxane-
fused BEDT-TTF, MET, and EDT-TTF derivatives 9a -
c. The results are summarized in Table 1. Cross-
coupling reaction between 17 and 2 equiv of 28 using
(EtO)3P as a trialkyl phoshite reagent gave the desired
product 9a in 22% yield (entry 1). The cis configuration
for the 1,4-dioxane ring of 9a was confirmed by an X-ray
crystallography (vide infra). The same product was
obtained in relatively higher yield when the cross-
coupling reaction was carried out by the use of (MeO)3P
in place of (EtO)3P (entry 2). Similarly, the (MeO)3P-
promoted coupling reaction with 29 produced 9b in 17%
yield (entry 3). However, 9c was not obtained by use of
the same molar excess of (MeO)3P as employed for the
synthesis of 9a and 9b (entry 4). Thus, we used a large
excess of (MeO)3P to obtain 9c (entry 5).
Oxidation potentials by cyclic voltammograms (CVs)
of the dioxane-fused donors 9a -c are summarized in
Table 2. The CVs of 9a and 9c showed two pairs of
reversible redox waves, whereas that of 9b consisted of
one pair of reversible redox waves and one irreversible
oxidation wave. For comparison with BEDT-TTF (2) and
BDDT-TTF (6),11 the oxidation potentials for these com-
pounds were measured under identical conditions. The
E1 value of the dioxane-fused BEDT-TTF derivative 9a
is higher by 0.04 V than that of 2, indicating that the
appended dioxane ring causes a decrease of the electron-
donating ability, whereas this value is equal to that of
6. While roughly the same ∆E (E2 - E1) values are
observed between 9a and 6, the ∆E (E2 - E1) value of 9a
is slightly larger than that of 2, implying a slight increase
in the on-site Coulombic repulsion involved in the forma-
tion of a dicationic species. The E1 value of the MET
derivative 9b is comparable to that of 9a , and the EDT-
TTF derivative 9c shows a lower E1 value than those of
9a and 9b.
Sch em e 3
to the participation of an SN1-like mechanism, since the
formation of trans isomers requires the substitution
reaction via a strictly SN2 process in the use of trans-
dichlorodioxane.5b It is thus noteworthy that an alterna-
tive synthetic route to the known dioxane-fused ketone
17 and thione 18 was accomplished via the BF3-promoted
reaction.5 In addition, bromination of 5,6-dihydro-1,4-
dithiin10 derived from 1,3-dithiol-2-one gave the unstable
dibromide 16 (eq 3, Scheme 3), which subsequently
reacted with tin dithiolate 13 with the aid of BF3‚OEt2
to produce the dithiane-fused ketone 19 as a single
stereoisomer in 68% yield. An X-ray crystallographic
study of 19 revealed that the dithiane ring was condensed
by cis fusion (Figure 3), in analogy to the dioxane ring of
17. Oxidation of the carbon-carbon single bond between
two S,S-acetals of 19 was achieved by treatment with
DDQ in boiling toluene for 2 days, furnishing the dihy-
drodithiin-fused ketone 20 in 60% yield. However,
introduction of the carbon-carbon double bond between
two S,O-acetals of 17 was unsuccessful under similar
conditions. Grignard reaction of the resulting ketones
17, 19, and 20 followed by trapping with Cl2SnBu2 gave
the tin-masked dithiolates 21-23 as precursors for the
Me3Al-promoted coupling synthesis, which were used for
the next reaction without purification through silica gel
chromatography. As described in the earlier report,7e
esters 24 and 27 (Figure 4) used for the Me3Al-promoted
coupling reaction could be prepared via a tin/lithium
transmetalation reaction. A sequence of analogous reac-
tions afforded ester 25 in 38% yield (eq 4, Scheme 3).
Finally, the readily prepared and/or commercially avail-
able thiones 28-30 were used for the (RO)3P-promoted
coupling reaction.
A single crystal of the BEDT-TTF derivative 9a suit-
able for an X-ray crystallographic study was obtained by
recrystallization from carbon disulfide. As shown in
Figure 5, 9a has a nonplanar structure, in which the
dioxane ring is forced to incline toward the outer ethylene
group linking two S atoms. Evidently, the whole molec-
ular structure of 9a is bulkier than that of BEDT-TTF
(2), but the dioxane ring added to the BEDT-TTF skeleton
results in no significant deformation of the molecular
structure of BEDT-TTF itself.12
Syn th esis of th e Dioxa n e-F u sed BEDT-TTF , MET,
a n d EDT-TTF Der iva tives. Although we first at-
tempted the synthesis of the dioxane-fused BEDT-TTF
derivative 9a by the Me3Al-promoted coupling reaction
of tin dithiolate 21 with ester 24, the desired product 9a
could not be obtained, as mentioned later. So, the
Syn th esis of th e Bis(d ith ia n e)-F u sed BEDT-TTF
Der iva tive. Synthesis of the bis(dithiane)-fused BEDT-
(11) Preparation of this compound by the coupling reaction between
17 and 18 was carried out according to ref 5a.
(12) For the molecular structure of BEDT-TTF, see: Kobayashi, H.;
Kobayashi, A.; Sasaki, Y.; Saito, G.; Inokuchi, H. Bull. Chem. Soc. J pn.
1986, 59, 301-302.
(10) For an alternative synthesis of this compound, see: Kato, R.;
Kobayashi, H.; Kobayashi, A. Synth. Metals 1991, 41-43, 2093-2096.

New TTF Donors with Extended Peripheral Substituents
J . Org. Chem., Vol. 63, No. 12, 1998 3955
Ta ble 1. Cr oss-Cou p lin g Rea ction of Keton e 17 w ith Th ion es 28-30
thione
(equiv)
(RO)3P
(equiv)
tempa
(°C)
reaction
time (h)
entry
solvent
product
yield (%)b
1
2
3
4
5
28 (2)
28 (2)
29 (2)
30 (2)
30 (2)
(EtO)3P (23)
(MeO)3P (23)
(MeO)3P (23)
(MeO)3P (23)
(MeO)3P (85)
benzene
benzene
benzene
benzene
benzene
100
100
100
100
100
4
3
3
3
3
9a
9a
9b
9c
9c
22
35
17
c
13
a
b
Oil bath temperature. After column chromatography on silica gel followed by recrystallization. c There was no detectable amount of
9c.
Ta ble 2. Oxid a tion P oten tia lsa of 9a -c, 2, a n d 6
course of the self-coupling reaction, since the difference
in conformational energy between two diastereomers of
7, similarly to those of 6, does not seem to be large enough
to enable the exclusive formation of one diastereomer.6
The insolubility of 7 in most organic solvents also did
not allow us to obtain its satisfactory CV data.
compd
E1
E2
∆E (E2 - E1)
9a
9b
9c
0.67
0.67
0.59
0.63
0.67
0.92
0.87b
0.86
0.86
0.93
0.25
0.20
0.27
0.23
0.26
BEDT-TTF (2)
BDDT-TTF (6)
Syn th esis of th e Dith ian e-Fu sed BEDT-TTF, MET,
a n d EDT-TTF Der iva tives. Our first synthesis of the
dithiane-fused BEDT-TTF derivative 10a and the EDT-
TTF derivative 10c employed the Me3Al-promoted reac-
tion of tin dithiolate 22 with esters 24 and 25. In each
case the yield of the desired product was 11%. Thus, we
examined cross-coupling reaction of ketone 19 with
thiones 28 and 30 to improve the yields of 10a and 10c.
In addition, a similar reaction using ketone 19 and thione
29 was attempted to obtain the dithiane-fused MET
derivative 10b. The results are summarized in Table 3.
For the synthesis of 10a , the yields were dependent on
the molar equivalent of thione 28, on the phosphite
reagent (trimethyl or triethyl phosphite), and on the
reaction temperature (entries 1-4). Cross-coupling reac-
tion using 2 equiv of thione 28 and (EtO)3P as a phosphite
reagent with a temperature of 100 °C gave the highest
yield (entry 4). Similarly, the use of 2 equiv of thione 29
in place of 1 equiv of 29 could enhance the yield of 10b
(entries 5 and 6). However, in contrast to the cross-
coupling synthesis of 10a , the yields of 10c from cross-
coupling reactions were lower than that obtained from
the Me3Al-promoted reaction, even though (EtO)3P in
place of (MeO)3P was used (entries 7 and 8).
a
b
In PhCN:CS2 ) 1:1. Irreversible wave.
F igu r e 5. Molecular structure of 9a : (a) top view, (b) side
view.
The CVs of the BEDT-TTF derivative 10a and the
EDT-TTF derivative 10c showed two pairs of reversible
redox waves and one pair of quasi-reversible redox
waves: the first two oxidation waves could be defined
while the latter was not well-defined, and the CV of the
MET derivative 10b exhibited two pairs of reversible
redox waves and one poorly defined oxidation wave.
Table 4 summarizes the oxidation potentials of 10a -c
together with that of the dioxane-fused BEDT-TTF
derivative 9a measured under the same conditions. The
E1 value of 10a is lower by 0.04 V than that of 9a ,
suggesting that electron-donating ability is enhanced by
the replacement of the dioxane ring with the dithiane
TTF derivative 7 was carried out by the self-coupling
reaction of ketone 19 in neat (EtO)3P at 120 °C, and the
desired product was obtained in 9% yield along with
small amounts of the recovered ketone 19. In the
synthesis of BDDT-TTF (6) by phosphite-coupling reac-
tion between 17 and 18, it has been reported that the
formation of two diastereomers of 6 can be confirmed by
a
1H NMR spectrum study.5 On the other hand, the
assignment for the two diastereomers of 7 could not be
clearly made on the basis of 1H NMR analysis due to their
insolubility in appropriate solvents (e.g., CDCl3, THF-
d8, and CDCl3-CS2) for the analysis; however, it is
presumed that the two diastereomers were formed in the
Ta ble 3. Cr oss-Cou p lin g Rea ction of Keton e 19 w ith Th ion es 28-30
thione
(equiv)
tempa
(°C)
reaction
time (h)
entry
(RO)3P
solvent
product
yield (%)b
1
2
3
4
5
6
7
8
28 (1)
28 (2)
28 (2)
28 (2)
29 (1)
29 (2)
30 (2)
30 (2)
(MeO)3P
(MeO)3P
(MeO)3P
(EtO)3P
(EtO)3P
(EtO)3P
(MeO)3P
(EtO)3P
benzene
benzene
toluene
benzene
benzene
benzene
benzene
benzene
100
100
130
100
100
100
100
100
3
3
3
3
3
3
3
3
10a
10a
10a
10a
10b
10b
10c
10c
9
32
21
50
17
26
trace
3
a
b
Oil bath temperature. After column chromatography on silica gel followed by recrystallization.

3956 J . Org. Chem., Vol. 63, No. 12, 1998
Ta ble 4. Oxid a tion P oten tia lsa of 10a -c a n d 9a
Yamada et al.
compd
E1
E2
∆E (E2 - E1)
10a
10b
10c
9a
0.61
0.60
0.52
0.65
0.91b
0.92b
0.85b
0.94
0.30
0.32
0.33
0.29
a
b
In PhCN. One other poorly defined peak exists at a more
anodic potential.
F igu r e 7. Molecular structure of 11: (a) top view, (b) side
view.
Ta ble 5. Syn th esis of 12a -d via Me3Al-Med ia ted
Rea ction of Tin Th iola te 21 w ith Ester s 24-27
reaction
time
entry ester reaction temp
product yield (%)a
1
2
3
4
5
6
24
24
24
25
26
27
-78 °C f rtb 4 days
12a
12a
12a
12b
12c
12d
3c
14c
16c
14d
14c
27c
-78 °C f rt
-78 °C f rt
-78 °C f rt
-78 °C f rt
-78 °C f rt
overnight
2 days
2 days
2 days
2 days
F igu r e 6. Molecular structure of 10a : (a) top view, (b) side
view.
a
b
Overall yield from ketone 17. Room temperature. c After
column chromatography on silica gel followed by recrystallization.
After column chromatography on silica gel.
ring, and the ∆E (E2 - E1) value of 10a is comparable to
that of 9a . There is no remarkable difference between
the E1 values of 10a and 10b and the E1 value of 10c is
lower than those of 10a and 10b.
A single crystal of the dithiane-fused BEDT-TTF
derivative 10a was obtained by recrystallization from
carbon disulfide, and its molecular structure was deter-
mined by X-ray crystallography (Figure 6). The molec-
ular structure of 10a resembles that of its dioxane
analogue 9a (see Figure 5), though the crystallographic
data of 10a differs from those of 9a .
Syn th esis of th e Bis(d ih yd r od ith iin )- a n d Dih y-
d r od ith iin -F u sed BEDT-TTF Der iva tives. The self-
coupling reaction using (EtO)3P was explored with the
objective of converting ketone 20 into the bis(dihy-
drodithiin)-fused BEDT-TTF derivative 8. The coupling
reaction of 20 in neat (EtO)3P at 120 °C gave 8 in 56%
yield. For the synthesis of the dihydrodithiin-fused
BEDT-TTF derivative 11, we employed the Me3Al-
promoted coupling reaction. Reaction of the tin-masked
dithiolate 23 with ester 24 in the presence of Me3Al
produced 11 in 37% yield. Because of this moderate
yield, no attempt was made to examine the phoshite-
coupling synthesis of 11.
The oxidation potentials of 8 and 11 were measured
by cyclic voltammetry under the same conditions as used
for the measurement of the dithiane-fused BEDT-TTF
10a [8, E1 ) +0.68 V, E2 ) +0.94 V; 11, E1 ) +0.67 V,
E2 ) +0.95 V, E3 ) +1.52 V (vs SCE)]. In the CV of 8,
one other poorly defined peak existed at a more anodic
potential. The electron-donating abilities of 8 and 11
estimated by their E1 values are almost equal, whereas
the E1 value of 11 is higher by 0.06 V than that of its
dithiane analogue 10a (+0.61 V), indicating that intro-
duction of the CdC bond between two S,S-acetals de-
creases the donating ability. On the other hand, when
d
comparing the ∆E (E2 - E1) values of 11 (0.28 V) and
10a (0.30 V), the presence of the additional CdC bond
proves to induce a slight reduction in the on-site Cou-
lombic repulsion.
An X-ray crystallographic study of a single crystal of
11 obtained by recrystallization from carbon disulfide
revealed that the crystal was solvated with the composi-
tion (11)2CS2. The molecular structure of 11 in this
crystal exhibits a nonplanar conformation, in which the
molecule is bent around each individual intramolecular
S‚‚‚S axis existing in the five heterocycles and contains
four tetrathioethylene medium planes (Figure 7).
Syn th esis of th e Dioxola n e Der iva tive of MET
a n d Its An a logu es. As already mentioned, though an
attempt to synthesize the dioxane-fused donor 9a by the
Me3Al-promoted reaction of tin dithiolate 21 with ester
24 was unsuccessful, this reaction resulted in the produc-
tion of a new MET derivative with a 1,3-dioxolane ring
12a on the basis of the Me3Al-mediated rearrangement
of the existing two S,O-acetals in the two fused six-
membered heterocycles to the five-membered cyclic O,O-
and S,S-acetals. It was noted that, for synthesis of 12a ,
the addition order of Me3Al, tin dithiolate 21, and ester
24 affected the yield of the product. Initially, to a CH2Cl2
solution of 21 was added at -78 °C a hexane solution of
Me3Al, and then a CH2Cl2 solution of ester 24 was added
(entry 1 in Table 5). Under these operating conditions,
clean reaction did not take place, and the yield of 12a
was only 3%. An alternative addition order, (i) ester 24,
(ii) Me3Al, and then (iii) tin dithiolate 21, led to an
increase in the yield of 12a (entry 2). However, the
length of the reaction time had only a negligible influence
on the yield of 12a (entry 3). By the procedure used to
obtain entry 3, reaction of 21 with ester 25 gave the

New TTF Donors with Extended Peripheral Substituents
J . Org. Chem., Vol. 63, No. 12, 1998 3957
Ta ble 6. Oxid a tion P oten tia lsa of 12a -d
molecular structures of several compounds belonging to
this TTF family are nonplanar and bulky, we have
already found that the dioxane-fused BEDT-TTF deriva-
tive 9a produces the metallic radical-cation salts13 and
also that the dioxolane derivative of MET 12a forms a
metallic charge-transfer complex with TCNQ.9 There-
fore, our ongoing work is aimed at further development
of organic metals derived from bulky TTF donors, de-
scribed herein, and clarification of the steric effects of
the bulky substituents on the formation of conducting
salts.
compd
E1
E2
E3
∆E (E2 - E1)
12a
12b
12c
12d
0.57
0.53
0.62
0.53
0.84
0.92
1.02
0.83
1.58
0.27
0.39
0.40
0.30
1.58
a
In PhCN.
Exp er im en ta l Section
Gen er a l Meth od s. Melting points were measured in open
capillaries and are uncorrected. 1H NMR spectra and 13C
NMR spectra were recorded at 400 and 100 MHz, respectively.
1H NMR chemical shifts are expressed in parts per million (δ)
relative to CHCl3 (δ 7.24) as an internal reference. For 13C
NMR chemical shifts, the reference was the center peak of
chloroform-d (δ 77.0).
The cyclic voltammetric measurement was carried out at
room temperature under nitrogen in PhCN/CS2 (v/v ) 1/1),
PhCN, or CH3CN containing Bu4NClO4 (0.1 M) as a supporting
electrolyte at 50 mV s-1 by use of platinum working and
counter electrodes, and a SCE (saturated calomel electrode)
as the reference electrode.
The data of X-ray structures were collected on an Enraf-
Nonius CAD-4 (for 17, 19, 10a , and 12a ) and a Mac Science
MXC18 [for 9a and (11)2CS2] diffractometers equipped with
graphite monochromated Mo KR radiation (λ ) 0.71073 Å)
using the ω-2θ scan technique. All calculations were per-
formed using the Molen structure determination system (for
17, 19, 10a , and 12a ) and CRYSTAN (MacScience) [for 9a and
(11)2CS2].
F igu r e 8. Molecular structure of 12a : (a) top view, (b) side
view.
dioxolane derivative of MDT-TTF 12b (entry 4), and
reaction with ester 26 furnished the derivative of MDHT
[methylenedithio(dihydro)tetrathiafulvalene]7d 12c (entry
5). In addition, the derivative of DSDTF 12d could be
obtained by reaction with ester 27 in 27% overall yield
from ketone 17.
The CVs data for the dioxolane derivatives 12a -d are
summarized in Table 6. The CV of 12b consisted of two
pairs of reversible redox waves, whereas those of 12a and
12d showed three pairs of reversible redox waves though
the π-electron system of 12a , or 12d is the same as that
of 12b. The CV of the derivative of MDHT 12c exhibited
two pairs of reversible redox waves, and the E1 value of
12c is higher by 0.09 V than that of 12b. The E1 values
of 12b (0.53 V in PhCN and 0.54 V in CH3CN) are higher
than those of MDT-TTF (5, 0.47 V in PhCN and 0.49 V
in CH3CN) measured under identical conditions, sug-
gesting that the electron-donating ability is decreased by
the existence of a 1,3-dioxane ring.
Air- and/or moisture-sensitive reactions were carried out in
a dry reaction vessel.
Ma ter ia ls. Tetrahydrofuran (THF) was distilled from
sodium benzophenone ketyl under an argon atmosphere unless
otherwise noted. All other solvents were dried by appropriate
procedures and stored over molecular sieves. Boron trifluoride
diethyl etherate was distilled and stored prior to use. MeMgBr/
THF, NaOMe/MeOH, nBuLi/hexane, Me3Al/hexane, (Bu4N)2-
[Zn(dmit)2], 2,3-dichrolo-1,4-dioxane (15), ethyl 1,3-dithiolan-
2-carboxylate (26), 4,5-ethylenedithio-1,3-dithiole-2-thione (28),
and 1,3-dithiole-2-thione (30) were purchased and used with-
out further titration or purification. 1,3-Dithiol-2-one could
be obtained by reaction of 30 with Hg(OAc)2 in THF-AcOH7e
in 78% yield. 4,5-Methylenedithio-1,3-dithiole-2-thione (29),
though commercially available, could be prepared by reaction
of (Bu4N)2[Zn(dmit)2] with 6 equiv of dibromomethane in
refluxing THF under nitrogen for 1.5 h in 90% yield after
column chromatography on silica gel followed by recrystalli-
zation from hexane-CHCl3.
The molecular structure of 12a was confirmed by an
X-ray crystallographic analysis of its single crystal
obtained by recrystallization from carbon disulfide (Fig-
ure 8). The dioxolane ring is attached perpendicularly
to the MET molecule via a single bond, and the MET
framework itself is curved toward the dioxolane ring.
Accordingly, the dioxolane ring appended to the MET
molecule makes it bulkier than most donors so far
prepared.
2,2-Dibu tyl-2-sta n n a -1,3-d ith iolo[4,5-d ]-1,3-d ith iole-2-
th ion e (14). To a solution of (Bu4N)2[Zn(dmit)2] (2.83 g, 3.00
mmol) in THF (15 mL) was added a solution of Cl2SnBu2 (1.83
g, 6.02 mmol) in THF (6 mL) at room temperature under
nitrogen. After stirring for 1 h at that temperature, water
was added, and the aqueous layer was extracted with several
portions of CHCl3. The extracts were combined, dried over
MgSO4, concentrated under reduced pressure, and purified by
column chromatography on silica gel using CH2Cl2 as an eluent
to give 2.38 g (5.54 mmol) of 14 (92% yield): orange powder;
mp 157 °C dec from CH2Cl2-hexane; 1H NMR (CDCl3) δ 0.93
(t, J ) 7.3 Hz, 6 H), 1.38 (sixtet, J ) 7.3 Hz, 4 H), 1.63-1.88
(m, 8 H); 13C NMR (CDCl3) δ 13.6, 24.8, 26.7, 27.7, 128.5, 211.5.
4,5-(1,4-Dioxa n ed iyl-2,3-d ith io)-1,3-d ith iol-2-on e (17)
fr om Tin Th iola te 13. To a solution of tin dithiolate 13 (3.96
g, 9.58 mmol) in CHCl3 (50 mL) was added 1.1 mL (10 mmol)
Con clu sion
The BF3-promoted reaction of tin-masked dithiolates
with dihaloheterocycles followed by (RO)3P- or Me3Al-
promoted coupling reaction provides a new TTF family
containing a bis-fused heterocycle or a biheterocycle on
either or both sides of the TTF core. Although the
(13) Yamada, J .; Tanaka, S.; Anzai, H.; Sato, T.; Nishikawa, H.;
Ikemoto, I.; Kikuchi, K. J . Mater. Chem. 1997, 7, 1311-1312.

3958 J . Org. Chem., Vol. 63, No. 12, 1998
Yamada et al.
of 2,3-dichloro-1,4-dioxane (15) at room temperature under
nitrogen, and then 2.5 mL (20 mmol) of BF3‚OEt2 was added.
After the reaction mixture was stirred at room temperature
for 3 h, aqueous NaHCO3 was added, and the resulting
suspension was filtered through Celite. The aqueous layer was
extracted with several portions of CHCl3, and the extracts were
combined, dried over MgSO4, and then concentrated under
reduced pressure. Column chromatography of the residue on
silica gel by using hexane-CH2Cl2 as an eluent gave 2.31 g
(8.67 mmol) of 17 (91% yield): pale orange plate; mp 144 °C
measured 297.8747. Anal. Calcd for C7H6OS6: C, 28.16; H,
2.03. Found: C, 28.20; H, 2.17.
4,5-(5,6-Dih yd r o-1,4-d ith iin d iyl-2,3-d ith io)-1,3-d ith iol-
2-on e (20). A mixture of 19 (500 mg, 1.68 mmol) and DDQ
(574 mg, 2.53 mmol) in toluene (16 mL) was refluxed for 2
days, and the resulting suspension was filtered through a
Celite pad, the Celite being then washed with CH2Cl2. The
filtrate was concentrated under reduced pressure and purified
by column chromatography on silica gel using hexane-CH2Cl2
as an eluent to give 300 mg (1.01 mmol) of 20 (60% yield) and
168 mg (0.56 mmol) of the recovered 19, which could be
recycled: pale yellow powder; mp 163 °C dec from EtOH-
1
from EtOH; H NMR (CDCl3) δ 3.73 (m, 2 H), 4.06 (m, 2 H),
5.48 (s, 2 H); 13C NMR (CDCl3) δ 63.4, 78.9, 115.1, 189.4; MS,
m/z (% relative intensity) 268 (M+ + 2, 7), 266 (M+, 36), 86
(100); HRMS (EI) calcd for C7H6O3S4 265.9200, measured
265.9198. Anal. Calcd for C7H6O3S4: C, 31.56; H, 2.27.
Found: C, 31.80; H, 2.31
1
CH2Cl2; H NMR (CDCl3) δ 3.27 (s, 4 H); 13C NMR (CDCl3) δ
30.7, 120.2, 122.2, 191.0; MS, m/z (% relative intensity) 298
(M+ + 2, 33), 296 (M+, 100), 268 (53), 116 (36), 88 (93); HRMS
(EI) calcd for C7H4OS6 295.8586, measured 295.8602. Anal.
Calcd for C7H4OS6: C, 28.35; H, 1.36. Found: C, 28.45; H,
1.60
4,5-(1,4-Dioxan ediyl-2,3-dith io)-1,3-dith iole-2-th ion e (18).
To a solution of tin dithiolate 14 (2.15 g, 5.01 mmol) in CHCl3
(50 mL) was added 0.54 mL (5.0 mmol) of 2,3-dichloro-1,4-
dioxane (15) at room temperature under nitrogen, and then
1.23 mL (10 mmol) of BF3‚OEt2 was added. After stirring at
room temperature overnight, the same workup and purifica-
tion as described above furnished 891 mg (3.15 mmol) of 18
(63% yield): reddish-brown needles; mp 180 °C dec from EtOH;
1H NMR (CDCl3) δ 3.74 (m, 2 H), 4.06 (m, 2 H), 5.50 (s, 2 H);
13C NMR (CDCl3) δ 63.5, 78.2, 124.7, 209.6; MS, m/z (% relative
intensity) 284 (M+ + 2, 8), 282 (M+, 37), 86 (100); HRMS (EI)
calcd for C7H6O2S5 281.8971, measured 281.8970. Anal. Calcd
for C7H6O2S5: C, 29.76; H, 2.14. Found: C, 29.71; H, 2.42.
4,5-(1,4-Dioxa n ed iyl-2,3-d ith io)-1,3-d ith iol-2-on e (17)
fr om Th ion e 18. To a solution of thione 18 (518 mg, 1.83
mmol) in THF (distilled from CaH2, 50 mL) was added a
solution of Hg(OAc)2 (0.93 g, 2.93 mmol) in acetic acid (29 mL)
in one portion at room temperature. After stirring was
continued vigorously for 1 h, the same workup as described
previously7e was carried out. Column chromatography of the
crude product on silica gel by using hexane-CH2Cl2 as an
eluent gave 396 mg (1.49 mmol) of 17 (81% yield).
5,6-Dih yd r o-1,4-d ith iin . To a mixture of 1,3-dithiol-2-one
(3.40 g, 28.7 mmol) and potassium hydroxide (14.5 g, 258
mmol) in EtOH (287 mL) under nitrogen was added 19.8 mL
(230 mmol) of 1,2-dibromoethane. After the reaction mixture
was heated under reflux for 1 h, 5% HCl solution and water
were sequentially added, and the resulting mixture was
filtered through Celite. The aqueous layer was extracted with
several portions of CH2Cl2, and the extracts were combined,
dried over MgSO4, and concentrated. Column chromatography
of the residue on silica gel by using pentane and pentane-
CH2Cl2 as eluents afforded 2.84 g (24.0 mmol) of a light yellow
oil (84% yield), the 1H and 13C NMR spectra of which were
identical with those of the authentic samples prepared accord-
ing to the literature method:11 1H NMR (CDCl3) δ 3.18 (s, 4
H), 6.07 (s, 2 H); 13C NMR (CDCl3) δ 26.3, 114.3.
2,3-Dibr om o-1,4-d ith ia n e (16). To a solution of 5,6-
dihydro-1,4-dithiin (1.09 g, 9.22 mmol) in ether (distilled form
P2O5, 33 mL) at -78 °C was added dropwise 0.47 mL (9.12
mmol) of bromine via a syringe. After the reaction mixture
was allowed to warm to 0 °C, the resulting precipitate was
filtered off and washed with hexane to give 1.99 g (7.16 mmol)
of 16 as a pale brown powder, which was immediately used
for the next reaction due to its lability: 1H NMR (CDCl3) δ
2.74 (m, 2 H), 3.42 (m, 2 H), 5.52 (s, 2 H); 13C NMR (CDCl3) δ
25.1, 53.5.
4,5-(1,4-Dith ia n ed iyl-2,3-d ith io)-1,3-d ith iol-2-on e (19).
To a solution of tin dithiolate 13 (2.02 g, 4.89 mmol) and the
crude 16 (1.33 g, 4.78 mmol) in CHCl3 (49 mL) was added 1.25
mL (9.86 mmol) of BF3‚OEt2 at room temperature under
nitrogen. After the reaction mixture was stirred at room
temperature for 2 h, the same workup and purification
procedures as used for the preparation of 17 from 13 furnished
989 mg (3.31 mmol) of 19 (68% yield): pale yellow needles;
mp 167 °C from EtOH; 1H NMR (CDCl3) δ 2.98 (m, 2 H), 3.15
(m, 2 H), 4.89 (s, 2 H); 13C NMR (CDCl3) δ 28.3, 45.6, 110.3,
188.5; MS, m/z (% relative intensity) 300 (M+ + 2, 8), 298 (M+,
29), 118 (100); HRMS (EI) calcd for C7H6OS6 297.8743,
Con ver sion of Keton es (17, 19, a n d 20) in to Tin Dith io-
la tes (21-23) via Gr ign a r d Rea ction . These compounds
were prepared by the procedure described in the earlier
report7e unless otherwise noted.
4,5-(1,4-Dioxa n ed iyl-2,3-d it h io)-2,2-d ib u t yl-2-st a n n a -
1
1,3-d ith iole (21): yellow powder; mp 109-110 °C; H NMR
(CDCl3) δ 0.90 (t, J ) 7.3 Hz, 3 H), 0.91 (t, J ) 7.3 Hz, 3 H),
1.34 (m, 4 H), 1.49-1.87 (m, 8 H), 3.64 (m, 2 H), 4.07 (m, 2
H), 5.28 (s, 2 H); 13C NMR (CDCl3) δ 13.6, 21.8, 23.1, 26.6,
26.7, 27.5, 28.1, 63.2, 79.5, 116.7.
4,5-(1,4-Dit h ia n ed iyl-2,3-d it h io)-2,2-d ibu t yl-2-st a n n a -
1,3-d ith iole (22). The reaction of ketone 19 with MeMgBr
in THF was carried out for 4 h: pale brown powder; mp 104-
105 °C; 1H NMR (CDCl3) δ 0.91 (t, J ) 7.3 Hz, 6 H), 1.35
(sixtet, J ) 7.3 Hz, 4 H), 1.56-1.88 (br, 8 H), 2.88 (m, 2 H),
3.12 (m, 2 H), 4.70 (s, 2 H); 13C NMR (CDCl3) δ 13.6, 22.3,
23.0, 26.6, 26.7, 27.7, 28.0, 28.1, 46.8, 112.2.
4,5-(5,6-Dih yd r o-1,4-d ith iin d iyl-2,3-d ith io)-2,2-d ibu tyl-
2-sta n n a -1,3-d ith iole (23): brown powder; mp 76 °C; 1H NMR
(CDCl3) δ 0.91 (t, J ) 7.3 Hz, 6 H), 1.34 (sixtet, J ) 7.3 Hz, 4
H), 1.58-1.85 (m, 8 H), 3.20 (s, 4 H); 13C NMR (CDCl3) δ 13.6,
23.7, 26.7, 27.7, 30.6, 120.4, 126.4.
2,2-Dibu tyl-2-sta n n a -1,3-d ith iole. In a 200-mL flask with
a septum inlet was placed 1.18 g (10 mmol) of 1,3-dithiol-2-
one, and this flask was cooled in a water bath. After a
methanol solution of NaOMe (1M × 20 mL, 20 mmol) was
added to that flask via a syringe under nitrogen, the reaction
mixture was stirred for 10 min and then cooled to - 78 °C. To
the cooled mixture was added dropwise for 1 h a solution of
3.03 g (10 mmol) of Cl2SnBu2 in THF (100 mL), and the
reaction mixture was allowed to warm to 0 °C. Water was
added, the mixture was extracted with several portions of
CH2Cl2, and the extracts were combined. The combined
extracts were dried over MgSO4, concentrated in vacuo, and
purified by column chromatography on silica gel using hex-
ane-CH2Cl2 as an eluent to afford 1.94 g (6.0 mmol) of a pale
yellow oil (60% yield): 1H NMR (CDCl3) δ 0.90 (t, J ) 7.3 Hz,
6 H), 1.35 (sixtet, J ) 7.3 Hz, 4 H), 1.30-1.80 (m, 8 H), 6.44
(s, 2 H, J H,Sn ) 63.5 Hz); 13C NMR (CDCl3) δ 13.6, 22.2, 26.6,
27.9, 120.0.
Meth yl 1,3-Dith iole-2-ca r boxyla te (25). To a solution of
725 mg (2.24 mmol) of 2,2-dibutyl-2-stanna-1,3-dithiole in THF
(23 mL) at -78 °C under nitrogen was added dropwise for 10
min a hexane solution of nBuLi (1.64 M × 2.8 mL, 4.59 mmol).
After stirring was continued for 20 min at that temperature,
a solution of commercially available methyl dichloroacetate
(0.24 mL, 2.32 mmol) in THF (12 mL) was added dropwise for
30 min, and the reaction mixture was allowed to warm to 0
°C. Saturated aqueous NH4Cl solution was added, the mixture
was extracted with several portions of CH2Cl2, and the extracts
were combined. The combined extracts were dried over
MgSO4, concentrated under reduced pressure, and purified by
column chromatograghy on silica gel using hexane and hex-
ane-CH2Cl2 as eluents to give 137 mg (0.84 mmol) of 25 (38%
1
yield): pale orange oil; H NMR (CDCl3) δ 3.75 (s, 3 H), 5.31
(s, 1 H), 5.98 (s, 2 H); 13C NMR (CDCl3) δ 51.8, 53.4, 116.2,

New TTF Donors with Extended Peripheral Substituents
J . Org. Chem., Vol. 63, No. 12, 1998 3959
169.2; MS, m/z (% relative intensity) 164 (M+ + 2, 3), 162 (M+,
31), 103 (100).
473.7990, measured 473.7974. Anal. Calcd for C12H10S10: C,
30.35; H, 2.12. Found: C, 30.46; H, 2.14.
(1,4-Dith ia n ed iyl-2,3-d ith io)tetr a th ia fu lva len e (DTT,
10c) via Me3Al-P r om oted Rea ction . This compound was
synthesized from the crude tin dithiolate 22 (1.25 mmol based
on 19) and ester 25 (1.99 mmol) in the presence of Me3Al (2.48
mmol) by the same procedure as described above, except that
the mixture of 22 and Me3Al was stirred at -78 °C for 1 h
prior to the addition of ester 25 at room temperature: orange
powder; mp 189 °C dec from CS2-EtOH; 1H NMR (CDCl3-
CS2) δ 2.94 (m, 2 H), 3.13 (m, 2 H), 4.79 (s, 2 H), 6.30 (s, 2 H);
MS, m/z (% relative intensity) 386 (17, M+ + 2), 384 (47, M+),
266 (100), 118 (80), 76 (40); HRMS (EI) calcd for C10H8S8
383.8392, measured 383.8392.
Gen er a l P r oced u r e for Cr oss Cou p lin g Rea ction of
Keton e 19 a n d Th ion es 28-30. Entry 4 in Table 3 is
representative. In a 50-mL flask under nitrogen were placed
ketone 19 (149 mg, 0.50 mmol), thione 28 (224 mg, 1.0 mmol),
benzene (8.3 mL), and triethyl phosphite (2.3 mL, 13 mmol).
The mixture was heated over an oil bath at 100 °C and kept
at that temperature for 3 h with stirring. After the resulting
suspension was cooled to 0 °C and diluted with hexane, the
precipitate was filtered off and washed with hexane. Purifica-
tion by silica gel column chromatography using CS2 as an
eluent, followed by recrystallization from CS2, gave 121 mg
(0.25 mmol) of 10a (50% yield).
Gen er a l P r oced u r e for Cr oss Cou p lin g Rea ction of
Keton e 17 a n d Th ion es 28-30. Entry 2 in Table 1 is
representative. In a 100-mL flask under nitrogen were placed
ketone 17 (533 mg, 2.0 mmol), thione 28 (898 mg, 4.0 mmol),
benzene (33 mL), and trimethyl phosphite (5.4 mL, 46 mmol).
The mixture was heated over an oil bath at 100 °C and kept
at that temperature for 3 h with stirring. After cooling to room
temperature, water was added and the mixture was extracted
with several portions of carbon disulfide. The extracts were
combined, dried over MgSO4, and concentrated under reduced
pressure. Purification by silica gel column chromatography
using CS2 and CS2-CH2Cl2 as eluents, followed by recrystal-
lization from CS2-EtOH, furnished 312 mg (0.70 mmol) of 9a
(35% yield).
(1,4-Dioxa n ed iyl-2,3-d it h io)et h ylen ed it h iot et r a t h ia -
fu lva len e (DOET, 9a ): orange plate; mp 179 °C dec from CS2;
1H NMR (CDCl3-CS2) δ 3.24 (m, 2 H), 3.31 (m, 2 H), 3.68 (m,
2 H), 4.04 (m, 2 H), 5.40 (s, 2 H); MS, m/z (% relative intensity)
444 (M+ + 2, 3), 442 (M+, 8), 356 (11), 86 (100), 76 (90); HRMS
(EI) calcd for C12H10O2S8 441.8447, measured 441.8469. Anal.
Calcd for C12H10O2S8: C, 32.55; H, 2.28. Found: C, 32.84; H,
2.40.
(1,4-Dioxa n e d iyl-2,3-d it h io)m e t h yle n e d it h iot e t r a -
th ia fu lva len e (DOMT, 9b). This compound was purified by
silica gel column chromatography using hexane-CH2Cl2 as an
eluent, followed by recrystallization from CS2-EtOH; dark red
powder: mp 173 °C dec from CHCl3-EtOH; 1H NMR (CDCl3-
CS2) δ 3.69 (m, 2 H), 4.04 (m, 2 H), 4.82 (d, J ) 9.8 Hz, 1 H),
5.04 (d, J ) 9.8 Hz, 1 H), 5.41 (s, 2 H); MS, m/z (% relative
intensity) 428 (M+, 1), 342 (2), 236 (24), 86 (100), 58 (82);
HRMS (EI) calcd for C11H8O2S8 427.8290, measured 427.8297.
Anal. Calcd for C11H8O2S8: C, 30.81; H, 1.88. Found: C,
30.59; H, 2.03.
(1,4-Dioxa n ed iyl-2,3-d it h io)t et r a t h ia fu lva len e (DOT,
9c): greenish-yellow powder; mp 154 °C dec from CS2-EtOH;
1H NMR (CDCl3) δ 3.69 (m, 2 H), 4.06 (m, 2 H), 5.41 (s, 2 H),
6.31 (s, 2 H); MS, m/z (% relative intensity) 354 (M+ + 2, 22),
352 (M+, 74), 266 (83), 86 (100); HRMS (EI) calcd for C10H8O2S6
351.8849, measured 351.8847.
Bis(1,4-d it h ia n e d iyl-2,3-d it h io)t e t r a t h ia fu lva le n e
(BDTET, 7). In a 30-mL flask under nitrogen were placed
ketone 19 (203 mg, 0.68 mmol) and triethyl phosphite (6.8 mL).
After the mixture was heated at 120 °C for 1.5 h with stirring,
the suspension was cooled to 0 °C and diluted with hexane.
The resulting precipitate was filtered off, washed with hexane,
and purified by column chromatography on silica gel using CS2
as an eluent, followed by recrystallization from CS2-EtOH,
to gave 15 mg (0.03 mmol) of 7 (9% yield): pale red powder;
mp 222 °C dec from CS2-EtOH; MS, m/z (% relative intensity)
566 (M+ + 2, 10), 564 (M+, 18), 118 (62), 76 (100); HRMS (EI)
calcd for C14H12S12 563.7588, measured 563.7587. Anal. Calcd
for C14H12S12: C, 29.76; H, 2.14. Found: C, 29.64; H, 2.19.
(1,4-D it h ia n e d iy l-2,3-d it h io )e t h y le n e d it h io t e t r a -
th ia fu lva len e (DTET, 10a ) via Me3Al-P r om oted Rea ction .
To a solution of the crude tin dithiolate 22 (2.0 mmol based
on 19) in CH2Cl2 (20 mL) was added a hexane solution of Me3Al
(1.08 M × 3.7 mL, 4.0 mmol) at -78 °C under nitrogen. After
stirring at that temperature for 1.5 h, the reaction mixture
was brought up to room temperature, and then a solution of
ester 24 (485 mg, 1.9 mmol) in CH2Cl2 (10 mL) was added.
The reaction mixture was stirred overnight before being
quenched with saturated aqueous NaHCO3. The resulting
mixture was filtered through Celite, and the aqueous layer
was extracted with several portions of CS2. The combined
extracts were dried over MgSO4, concentrated under reduced
pressure, and purified by column chromatography on silica gel
using hexane and CS2 as eluents, followed by recrystallization
from CS2, giving 104 mg (0.22 mmol) of 10a (11% yield):
reddish-orange plate; mp 202 °C dec from CS2; 1H NMR
(CDCl3-CS2) δ 2.94 (m, 2 H), 3.12 (m, 2 H), 3.27 (m, 4 H),
4.79 (s, 2 H); MS, m/z (% relative intensity) 474 (0.6, M+), 356
(1,4-Dith ia n ed iyl-2,3-d ith io)m eth ylen ed ith iotetr a th i-
a fu lva len e (DTMT, 10b): brownish-yellow powder; mp 193
1
°C dec from CS2; H NMR (CDCl3-CS2) δ 2.94 (m, 2 H), 3.13
(m, 2 H), 4.80 (s, 2 H), 4.86 (d, J ) 9.8 Hz, 1 H), 5.01 (d, J )
9.8 Hz, 1 H); MS, m/z (% relative intensity) 460 (0.5, M+), 342
(0.8), 236 (25), 118 (100), 90 (78). Anal. Calcd for C11H8S10
C, 28.67; H, 1.75. Found: C, 28.43; H, 1.70.
:
Bis(5,6-d ih yd r o-1,4-d ith iin d iyl-2,3-d ith io)tetr a th ia fu l-
va len e (BDHDI-TTF , 8). This compound was synthesized
from ketone 20 by the procedure used for the preparation of
7, except that the mixture of 20 and triethyl phosphite was
heated for 2 h: yellow powder; mp 264 °C dec from CS2-EtOH;
1H NMR (CDCl3-CS2) δ 3.23 (s, 8 H); MS, m/z (% relative
intensity) 562 (3, M+ + 2), 560 (5, M+), 384 (33), 356 (20), 88
(39), 76 (100); HRMS (EI) calcd for C14H8S12 559.7275, mea-
sured 559.7273. Anal. Calcd for C14H8S12: C, 29.97; H, 1.44.
Found: C, 30.31; H, 1.55.
(5,6-Dih yd r o-1,4-d it h iin d iyl-2,3-d it h io)e t h yle n e d i-
th iotetr a th ia fu lva len e (DHDIET, 11). To a solution of the
crude tin dithiolate 23 (0.71 mmol based on 20) in CH2Cl2 (10
mL) was successively added a hexane solution of Me3Al (1.07
M × 1.3 mL, 1.39 mmol) and a CH2Cl2 (10 mL) solution of
ester 24 (177 mg, 0.70 mmol) at -78 °C under nitrogen. After
the reaction mixture was allowed to warm to room tempera-
ture and stirred overnight, the same workup and purification
as described in preparation of 10a via Me3Al-promoted reac-
tion, followed by recrystallization from CS2-hexane, furnished
125 mg (0.26 mmol) of 11 (37% yield): orange needles; mp 231
°C dec for (11)2CS2 from CS2; 1H NMR (CDCl3-CS2) δ 3.23 (s,
4 H), 3.28 (s, 4 H); MS, m/z (% relative intensity) 474 (29, M+
+ 2), 472 (54, M+), 384 (100), 356 (77), 88 (89), 76 (75); HRMS
(EI) calcd for C12H8S10 471.7833, measured 471.7817. Anal.
Calcd for (11)2CS2 (C25H16S22): C, 29.38; H, 1.58. Found: C,
29.49; H, 1.54.
A Typ ica l P r oced u r e for Syn th esis of th e Dioxola n e
Der iva tives. Synthesis of 12a (entry 3 in Table 6) is
representative. To a solution of ester 24 (0.80 mmol) in CH2Cl2
was added a hexane solution of Me3Al (1.02 M × 1.6 mL, 1.63
mmol) at -78 °C under nitrogen, and then a CH2Cl2 (8.0 mL)
solution of the crude tin dithiolate 21 (377 mg, 0.80 mmol
based on 17) was added. The reaction mixture was allowed
to warm to room temperature, and stirring was continued for
2 days. The usual workup and purification by silica gel column
chromatography using hexane and hexane-CHCl3 as eluents,
followed by recrystallization from CHCl3-EtOH, afforded 58
mg (0.13 mmol) of 12a (16% yield from ketone 17).
[(1,3-D io x o la n -2-y l)m e t h y lid y n e d it h io ]e t h y le n e -
d ith iotetr a th ia fu lva len e (DO-MET, 12a ): orange needles;
mp 178 °C dec from CS2; 1H NMR (CDCl3) δ 3.27 (m, 4 H),
(3), 118 (100), 76 (100); HRMS (EI) calcd for
C12H10S10

3960 J . Org. Chem., Vol. 63, No. 12, 1998
Yamada et al.
4.00 (m, 4 H), 5.05 (d, J ) 5.6 Hz, 1 H), 5.20 (d, J ) 5.6 Hz, 1
H); MS, m/z (% relative intensity) 444 (13, M+ + 2), 442 (37,
M+), 380 (24), 307 (59), 73 (100); HRMS (EI) calcd for
6.571(2) Å, â ) 96.93(3)°, V ) 1686.1(9) Å3, Z ) 4, Dc ) 1.741
g cm-3, µ ) 26.85 cm-1, F(000) ) 272. The ω-2θ scan
technique was used to a maximum 2θ of 55°. Cell constants
were determined from 25 carefully centered reflections in the
range 25° < 2θ < 30°. The structure was solved by a direct
method and refined by full-matrix least-squares analysis
(anisotropic for non-hydrogen atoms) to R ) 0.043, Rw ) 0.049
for 2852 observed [I g 2σ(I)] reflections from 3604 independent
reflections.
Cr ysta l d a ta for 10a :14 C12H10S10, M ) 474.85, triclinic,
space group Po(1,j), a ) 8.788(1) Å, b ) 9.998(2) Å, c )
11.126(2) Å, R ) 80.09(1)°, â ) 68.01(1)°, γ ) 82.17(1)°, V )
890.0(3) Å3, Z ) 2, Dc ) 1.772 g cm-3, µ ) 11.82 cm-1, F(000)
) 484. The ω-2θ scan technique was used to a maximum 2θ
of 80°. Cell constants were determined from 25 carefully
centered reflections in the range 35.9° < 2θ < 39.6°. The
structure was solved by a direct method and refined by full-
matrix least-squares analysis (anisotropic for non-hydrogen
atoms) to R ) 0.052, Rw ) 0.047 for 5307 observed [I g 3σ(I)]
reflections from 8935 unique data.
Cr ysta l d a ta for (11)2CS2:14 C25H16S22, M ) 1021.84,
monoclinic, space group p21/n, a ) 12.330(7) Å, b ) 24.22(1) Å,
c ) 6.553(4) Å, â ) 98.01 (5)°, V ) 1938.3(2) Å3, Z ) 4, Dc )
1.617 g cm-3, µ ) 10.85 cm-1, F(000) ) 518. The ω-2θ scan
technique was used to a maximum 2θ of 60°. Cell constants
were determined from 38 carefully centered reflections in the
range 20° < 2θ < 30°. The structure was solved by a direct
method and refined by full-matrix least-squares analysis
(anisotropic for non-hydrogen atoms) to R ) 0.068, Rw ) 0.084
for 3318 observed [I g 3σ(I)] reflections from 3745 unique data.
Cr ysta l Da ta for 12a :14 C12H10O2S8, M ) 442.72, mono-
clinic, space group P21/n, a ) 6.322(1) Å, b ) 25.093(2) Å, c )
10.637(1) Å, â ) 93.62(1)°, V ) 1684.1(3) Å3, Z ) 4, Dc ) 1.746
g cm-3, µ ) 10.2 cm-1, F(000) ) 904. The ω-2θ scan technique
was used to a maximum 2θ of 80°. Cell constants were
determined from 25 carefully centered reflections in the range
26.5° < 2θ < 35.6°. The structure was solved by the Patterson
method and refined by full-matrix least-squares analysis
(anisotropic for non-hydrogen atoms) to R ) 0.045, Rw ) 0.051
for 6244 observed [I g 1.5σ(I)] reflections from 10416 unique
data.
C
12H10O2S8 441.8447, measured 441.8467. Anal. Calcd for
C12H10O2S8: C, 32.55; H, 2.28. Found: C, 32.57; H, 2.45.
[(1,3-D io x o la n -2-y l)m e t h y lid y n e d it h io ]t e t r a t h ia -
fu lva len e (DO-MDT, 12b): brownish-yellow needles; mp
1
113-114 °C from CS2-EtOH; H NMR (CDCl3) δ 4.00 (m, 4
H), 5.05 (d, J ) 5.4 Hz, 1 H), 5.21 (d, J ) 5.4 Hz, 1 H), 6.31 (s,
2 H); MS, m/z (% relative intensity) 354 (26, M+ + 2), 352 (100,
M+), 279 (54), 146 (24), 73 (48); HRMS (EI) calcd for C10H8O2S6
351.8849, measured 351.8848. Anal. Calcd for C10H8O2S6: C,
34.06; H, 2.29. Found: C, 34.04; H, 2.40.
[(1,3-D i o x o la n -2-y l)m e t h y li d y n e d i t h i o ]d i h y d r o -
tetr a th ia fu lva len e (DO-MDHT, 12c): light brown plate; mp
137 °C dec from CHCl3-EtOH; 1H NMR (CDCl3) δ 3.44 (m, 4
H), 3.98 (m, 4 H), 5.02 (d, J ) 5.9 Hz, 1 H), 5.20 (d, J ) 5.9
Hz, 1 H); MS, m/z (% relative intensity) 356 (20, M+ + 2), 354
(71, M+), 281 (68), 148 (28), 73 (100); HRMS (EI) calcd for
C10H10O2S6 353.9005, measured 353.8987. Anal. Calcd for
C
10H10O2S6: C, 33.87; H, 2.84. Found: C, 33.93; H, 2.86.
Dim e t h yl[(1,3-Dioxola n -2-yl)m e t h ylid yn e d it h io]d i-
selen a d ith ia fu lva len e (DMDO-STF , 12d ): dark red pow-
der; mp 198 °C dec from CHCl3-EtOH; 1H NMR (CDCl3) δ
1.98 (s, 6 H), 3.99 (m, 4 H), 5.02 (d, J ) 5.6 Hz, 1 H), 5.20 (d,
J ) 5.6 Hz, 1 H); MS, m/z (% relative intensity) 476 (100, M+
+ 2), 474 (77, M+), 403 (44), 401 (40), 270 (19), 268 (18), 73
(77); HRMS (EI) calcd for C12H12O2S680Se2 475.8051, measured
475.8052. Anal. Calcd for C12H12O2S4Se2: C, 30.38; H, 2.55.
Found: C, 30.28; H, 2.57.
Cr ysta l d a ta for 17:14 C7H6O3S4, M ) 266.38, monoclinic,
space group P21, a ) 9.182(1) Å, b ) 5.461(2) Å, c ) 9.920(1)
Å, â ) 91.19(1)°, V ) 497.3(2) Å3, Z ) 2, Dc ) 1.779 g cm-3, µ
) 8.9 cm-1, F(000) ) 272. The ω-2θ scan technique was used
to a maximum 2θ of 70°. Cell constants were determined from
25 carefully centered reflections in the range 26.5° < 2θ <
35.6°. The structure was solved by the Patterson method and
refined by full-matrix least-squares analysis (anisotropic for
non-hydrogen atoms) to R ) 0.021, Rw ) 0.029 for 1926
observed [I g 3σ(I)] reflections from 2368 unique data.
Cr ysta l d a ta for 19:14 C7H6OS6, M ) 298.51, monoclinic,
space group P21/c, a ) 5.171(2) Å, b ) 11.269(3) Å, c )
18.897(1) Å, â ) 90.10(2)°, V ) 1101.2(6) Å3, Z ) 4, Dc ) 1.800
g cm-3, µ ) 11.6 cm-1, F(000) ) 608. The ω-2θ scan technique
was used to a maximum 2θ of 70°. Cell constants were
determined from 25 carefully centered reflections in the range
24.2° < 2θ < 42.3°. The structure was solved by the Patterson
method and refined by full-matrix least-squares analysis
(anisotropic for non-hydrogen atoms) to R ) 0.038, Rw ) 0.042
for 1824 observed [I g 3σ(I)] reflections from 4841 unique data.
Cr ysta l d a ta for 9a :14 C12H10O2S8, M ) 442.72, monoclinic,
space group P21/n, a ) 12.005(3) Å, b ) 21.532(2) Å, c )
Ack n ow led gm en t. This work was supported by a
Grant-in-Aid for Scientific Research (No. 08640694)
from the Ministry of Education, Science, Sports and
Culture, J apan.
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra of
2,2-dibutyl-2-stanna-1,3-dithiole and compounds 9c, 10c, 14,
16, 21, 22, 23, and 25 (5 pages). This material is contained
in libraries on microfiche, immediately follows this article in
the microfilm version of the journal, and can be ordered from
the ACS; see any current masthead page for ordering
information.
(14) The author has deposited atomic coordinates for this structure
with the Cambridge Crystallographic Data Centre. The coordinates
can be obtained, on request, from the Director, Cambridge Crystal-
lographic Data Centre, 12 Union Road, Cambridge, CB2 1EZ, UK.
J O972337Y