Synthetic procedure for various selenium-containing electron donors of the bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) type

Article abstract of DOI:10.1021/jo016393h

Six selenium variants of BEDT-TTF have been successfully synthesized by a newly developed synthetic method that involves a combination of two key reactions for the construction of two kinds of heterocyclic rings: the first is a one-pot formation of 1,3-dichalcogenole-2-chalcogenones from a common starting material, THP-protected 2-(ethynylthio)ethanol, leading to the inner five-membered rings, and the other is the annelation of the outer six-membered heterocyclic ring onto the inner ring by an intramolecular transalkylation reaction on a chalcogen atom. This method turned out to be widely applicable to the syntheses of the electron donors of bis(ethylenedithio)- and bis(ethyleneselenothio)-substituted types. However, synthetic attempts to form analogous donors of the bis(ethylenediseleno)-substituted type from THP-protected 2-(ethynylseleno)ethanol were unsuccessful. This is attributable to the predominance of side-reactions via a seleniranium (episelenonium) salt over the desired six-membered ring formation by transalkylation via a seleninium salt.

Full text of DOI:10.1021/jo016393h

4218
J . Org. Chem. 2002, 67, 4218-4227
Syn th etic P r oced u r e for Va r iou s Selen iu m -Con ta in in g Electr on
Don or s of th e Bis(Eth ylen ed ith io)tetr a th ia fu lva len e (BEDT-TTF )
Typ e
Kazuo Takimiya,* Tetsuya J igami, Minoru Kawashima, Mie Kodani, Yoshio Aso, and
Tetsuo Otsubo*
Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University,
Higashi-Hiroshima 739-8527, J apan
ktakimi@hiroshima-u.ac.jp
Received December 19, 2001
Six selenium variants of BEDT-TTF have been successfully synthesized by a newly developed
synthetic method that involves a combination of two key reactions for the construction of two kinds
of heterocyclic rings: the first is a one-pot formation of 1,3-dichalcogenole-2-chalcogenones from a
common starting material, THP-protected 2-(ethynylthio)ethanol, leading to the inner five-membered
rings, and the other is the annelation of the outer six-membered heterocyclic ring onto the inner
ring by an intramolecular transalkylation reaction on a chalcogen atom. This method turned out
to be widely applicable to the syntheses of the electron donors of bis(ethylenedithio)- and
bis(ethyleneselenothio)-substituted types. However, synthetic attempts to form analogous donors
of the bis(ethylenediseleno)-substituted type from THP-protected 2-(ethynylseleno)ethanol were
unsuccessful. This is attributable to the predominance of side-reactions via a seleniranium
(episelenonium) salt over the desired six-membered ring formation by transalkylation via a
seleninium salt.
In tr od u ction
partial replacement of the eight sulfur atoms of BEDT-
TTF by selenium, there are nearly fifty selenium vari-
ants. Even if unsymmetrical types with respect to the
central double bond are excluded,5 nine selenium-
containing compounds (1b-j) can be designed as shown
in Chart 1. Among them, the three highly symmetrical
compounds bis(ethylenedithio)tetraselenafulvalene (BETS,
1b),6 bis(ethylenediseleno)tetrathiafulvalene (BEDSe-
TTF, 1h ),7 and bis(ethylenediseleno)tetraselenafulvalene
(BEDSe-TSF, 1i)8 have been synthesized and recognized
to possess remarkable abilities to form highly conductive
radical cation salts. In particular, BETS is a unique
organic donor in that it can give unprecedented magnetic
organic superconductors.6d However, the previous meth-
Since the discovery of the very high conductivity of
tetrathiafulvalene (TTF)-tetracyanoquinodimethane, struc-
tural modifications of TTF have been extensively carried
out in search of better electron donors, and as a result,
more than 1000 TTF derivatives have been prepared.1
The most successful compound is bis(ethylenedithio)-
tetrathiafulvalene (BEDT-TTF, 1a ), which has provided
more than fifty superconducting radical cation salts,2
involving κ-(BEDT-TTF)2‚Cu[N(CN)2]Cl with the highest
transition temperature Tc ) 12.8 K at 0.3 kbar among
organic superconductors except for those of A3C60 type.3
As the replacement of skeletal sulfur atoms of TTF
derivatives by selenium atoms is generally recognized as
an effective approach to superior electron donors with
enhanced intermolecular interactions,4 selenium variants
of BEDT-TTF have aroused much interest. Considering
(5) Only three unsymmetrical derivatives with respect to the central
double bond have been reported. Bis(ethylenedithio)diselenadithia-
fulvalene: Naito, T.; Kobayashi, H.; Kobayashi, A. Bull. Chem. Soc.
J pn. 1997, 70, 107-114. Ethylenediselenoethylenedithiotetra-
thiafulvalene: (a) Papavassiliou, G. C.; Kakoussis, V. C.; Lagouvardos,
D. J . Z. Naturforsch. 1991, 466, 1269-1271. (b) Binet, L.; Fabre, J .
M.; Becher, J . Synthesis 1997, 26-28. Bis(ethylnenedithio)selenot-
rithiafulvalene: Papavassiliou, G. C.; Lagouvardos, D. J .; Terzis, A.;
Hountas, A.; Hilti, B.; Zambounis, J . S.; Mayer, C. W.; Pfeiffer, J .;
Hofherr, W.; Delhaes, P.; Amiell, J . Synth. Met. 1993, 56, 2174-2179.
(6) (a) Schumaker, R. R.; Lee, V. Y.; Engler, E. M. J . Phys. 1983,
C3, 1139-1145. (b) Kato, R.; Kobayashi, H.; Kobayashi, A. Synth. Met.
1991, 42, 2093-2096. (c) Courcet, T.; Malfant, I.; Pokhodnia, K.;
Cassoux, P. New J . Chem. 1998, 5, 585-589. (d) Kobayashi, H.;
Kobayashi, A.; Cassoux, P. Chem. Soc. Rev. 2000, 29, 325-333 and
references therein; (e) Very recently, magnetic-field-induced super-
conductivity has been discovered in λ-(BETS)2FeCl4: Uji, S.; Shina-
gawa, H.; Terashima, T.; Yakabe, T.; Terai, Y.; Tokumoto, M.; Tanaka,
H.; Kobayashi, H. Nature 2001, 410, 908-910.
* To whom correspondence should be addressed. Phone: +81-824-
24-7734. Fax: +81-824-24-5494.
(1) For comprehensive reviews on TTF derivatives, see: (a) Schukat,
G.; Richter, A. M.; Fangha¨nel, E. Sulfur Rep. 1987, 7, 155-240. (b)
Schukat, G.; Fangha¨nel E. Sulfur Rep. 1993, 14, 245-390. (c) Schukat,
G.; Fangha¨nel E. Sulfur Rep. 1996, 18, 1-294.
(2) For comprehensive reviews on organic superconductors, see: (a)
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): Synthesis, Structure, Properties, and Theory;
Prentice Hall: Englewood Cliffs, NJ , 1992. (b) Ishiguro, T.; Yamaji,
K.; Saito, G. Organic Superconductors, 2nd ed.; Springer-Verlag:
Berlin, 1998.
(3) Williams, J . M.; Kini, A. M.; Wang, H. H.; Carlson, K. D.; Geiser,
U.; Montgomery, L. K.; Pyrka, G. J .; Watkins, D. M.; Kommers, J . M.;
Boryschuk, S. J .; Crouch, A. V. S.; Kwok, W. K.; Schirber, J . E.;
Overmyer, D. L.; J ung, D.; Whangbo, M.-H. Inorg. Chem. 1990, 29,
3272-3274.
(4) Cowan, D.; Kini, A. In The Chemistry of Organic Selenium and
Tellurium Compounds; Patai, S., Ed.; J ohn Wiley and Sons: New York,
1987; Vol. 2, pp 463-494.
(7) (a) Lee, V. Y. Synth. Met. 1987, 20, 161-167. (b) Hsu, S.-Y.;
Chiang, L. Y. Synth. Met. 1988, 27, B651-B656. (c) Kini, A. M.; Gates,
B. D.; Beno, M. A.; Williams, J . M. J . Chem. Soc., Chem. Commun.
1989, 169-171.
(8) (a) Lee, V. Y.; Engler, E. M.; Schumaker, R. R.; Parkin, S. S. P.
J . Chem. Soc., Chem. Commun. 1983, 235-236. (b) Zambounis, J . S.;
Mayer, C. W. Tetrahedron Lett. 1991, 32, 2741-2742.
10.1021/jo016393h CCC: $22.00 © 2002 American Chemical Society
Published on Web 05/15/2002

Synthesis of Selenium-Containing BEDT-TTF-Type Donors
Ch a r t 1
J . Org. Chem., Vol. 67, No. 12, 2002 4219
Sch em e 1
Sch em e 2
ods for synthesizing these selenium compounds are not
necessarily easy and lack generality. More specifically,
the synthesis of BETS was carried out only by lengthy
and difficult routes with low total yields. In addition,
these methods are hardly applicable to the syntheses of
the less symmetrical selenium variants of the ethylen-
eselenothio (BEST)-substituted type or of the diselena-
dithiafulvalene (STF) skeleton type. For the STF skeleton
type, only bis(ethylenedithio)diselenadithiafulvalene
(BEDT-STF, 1c) has been reported, but its synthetic yield
was very low (<0.5%), allowing the study of neither its
physical properties nor those of its radical cation salts.9
Thus, it is desirable to develop a general synthetic
method that is not only superior to the preceding ones of
BETS but also applicable to the syntheses of all the
selenium variants of BEDT-TTF.
Recently, we developed a general synthetic method for
novel TTF- and TSF-type electron donors (4) fused with
five- or six-membered heterocycles containing one chal-
cogen atom according to the outline shown in Scheme 1.10
This method involves one-pot formation of 1,3-dichalco-
genole-2-chalcogenones (3) from tetrahydropyran (THP)-
protected 3-butyn-1-ol or 4-pentyn-1-ol (2)11 followed by
the outer heterocycle formation via an intramolecular
transalkylation reaction on a chalcogen atom. A great
merit of this method lies in the fact that a series of
heterocycle-fused TTF-type donors are available from just
limited starting acetylene compounds by choosing the
appropriate chalcogen reagents.
2-(ethynylthio)ethanol (5) or 2-(ethynylseleno)ethanol (6),
as shown in Scheme 2. We have then examined the
potential of this approach for the syntheses of not only
BEDT-TTF itself (1a ) but also its selenium variants (1b-
j). In this paper, we report the scope and limitation of
the present method.12
Resu lts a n d Discu ssion
The 10 donors drawn in Chart 1 are roughly catego-
rized into three classes of BEDT, BEST, and BEDSe
types, according to the structures of the outer hetero-
cycles. The present synthetic approaches to these types
are justly linked to the starting THP-protected 2-(ethy-
nylchalcogeno)ethanols 5 and 6: the BEDT type can only
be derived from the sulfur-containing acetylene 5, the
BEDSe type only from the selenium-containing acetylene
(6), and the BEST type from either 5 or 6. The validity
and versatility of the present synthetic method are
described in the respective classes of BEDT, BEST, and
BEDSe.
Syn t h esis of BE DT-Su b st it u t ed Don or s (1a -c).
Although all the BEDT-type compounds, BEDT-TTF
(1a ),13 BETS (1b),6a,b and BEDT-STF (1c),9 are known,
we first tried to evaluate the validity of our synthetic
method for these compounds. The synthesis of the key
starting compound, THP-protected 2-(ethynylthio)ethanol
5, as well as its synthetic application to BEDT-TTF is
demonstrated in Scheme 3. A reaction of 2-iodoethyl
tetrahydropyranyl ether (8)14 with potassium thiocyanate
gave the corresponding thiocyanate 9 (85% yield), which
then reacted with ethynylmagnesium chloride to give 5
in 54% yield. The lithium acetylide derived from 5 with
equimolar n-BuLi in the presence of tetramethylethyl-
enediamine (TMEDA) was successively reacted with
sulfur, carbon disulfide, and finally methyl thiocyanate
to give the thione 7a in 76% yield, which was then
Another merit of this method is that it enables the
design of versatile donors with different outer ring sizes
or different heterocyclic rings by adopting appropriate
starting acetylene compounds. One may thus expect that
BEDT-TTF-type electron donors fused with six-mem-
bered heterocycles containing two chalcogen atoms (1)
are similarly accessible by starting with THP-protected
(9) Lagouvardos, D. J .; Papavassiliou, G. C. Z. Naturforsch. 1992,
47b, 898-900.
(10) (a) J igami, T.; Takimiya, K.; Aso, Y.; Otsubo, T. Chem. Lett.
1997, 1091-1092. (b) J igami, T.; Takimiya, K.; Otsubo, T.; Aso, Y. J .
Org. Chem. 1998, 63, 8865-8872. (c) J igami, T.; Takimiya, K.; Aso,
Y.; Otsubo, T. Synth. Met. 1999, 102, 1714-1715. (d) Kodani, M.;
Murakami, S.; J igami, T.; Takimiya, K.; Aso, Y.; Otsubo, T. Heterocycles
2001, 54, 225-234. (e) J igami, T.; Kodani, M.; Murakami, S.; Takimiya,
K.; Aso, Y.; Otsubo, T. J . Mater. Chem. 2001, 11, 1026-1033.
(11) Takimiya, K.; Morikami, A.; Otsubo, T. Synlett 1997, 319-321.
(12) The BEST-TTF and BEST-TSF of the present work have been
preliminarily reported in the proceedings of the International Confer-
ence on Science and Technology of Synthetic Metals 1998 (ICSM ’98),
Montpellier, France; J igami, T.; Kawashima, M.; Takimiya, K.; Aso,
Y.; Otsubo, T. Synth. Met. 1999, 102, 1619-1620.
(13) Mizuno, M.; Garito, A. F.; Cava, M. P. J . Chem. Soc., Chem.
Commun. 1978, 18-19.
(14) Hutchinson, D. W.; Thornton, D. M. Synthesis 1990, 135-137.

4220 J . Org. Chem., Vol. 67, No. 12, 2002
Takimiya et al.
Sch em e 4. Syn th esis of BETS (1b)a
Sch em e 3. Syn th esis of THP -P r otected
2-(Eth yn ylth io)eth a n ol (5) a n d BEDT-TTF (1a )a
a
Key: (i) KSCN, acetone, reflux; (ii) ethynylmagnesium chlo-
ride, THF, rt; (iii) n-BuLi, TMEDA, -70 °C; (iv) S, 0 °C; (v) CS2,
-90 °C; (vi) MeSCN; (vii) HCl aq MeOH-acetone, rt; (viii) TsCl,
pyridine, 0 °C; (ix) NaI, DMF, 95 °C; (x) Hg(OAc)2, CHCl3, rt; (xi)
b
P(OMe)3, reflux. From ref 15b. c From ref 19.
a
Key: (i) n-BuLi, TMEDA, -70 °C; (ii) Se, 0 °C; (iii) CSe2, -90
°C; (iv) MeSCN or EtSCN; (v) P(OMe)3, reflux; (vi) HCl aq, MeOH-
THF, rt; (vii) TsCl, pyridine (R ) Me) or Et3N (R ) Et), 0 °C; (viii)
NaI, DMF, 80 °C.
converted into 5,6-dihydro-2-thioxo-1,3-dithiolo[2,3-d]-
[1,4]dithiin (12a )15 via deprotection of THP group (10a ,
85% yield), tosylation (11a , 80% yield), and finally ring-
closing reaction (67% yield). Since the thione 12a was
already reported to be readily convertible to BEDT-TTF
(1a ) via the ketone 13a ,15b it follows that our synthetic
method can be applicable to BEDT-TTF (1a ). Here, we
do not intend to assert that the present method is useful
for the synthesis of BEDT-TTF, because since the first
synthesis of BEDT-TTF by Cava’s group,13 several im-
proved synthetic methods have already been developed.16
In addition, BEDT-TTF itself and the precursors 12a and
13a are commercially available these days, though still
expensive. Instead, we may emphasize that the inter-
mediate 7a is of special use as a counterpart for trialkyl
phospite-mediated cross-coupling directed torward the
synthesis of the hybrids consisting of half of the BEDT-
TTF. When 12a and 13a are directly used for such cross-
coupling reactions, cross-coupling hybrid products are
often difficult to isolate from the homocoupling products
by conventional purification techniques. However, use of
7a with the polar functional group facilitates the chro-
matographic separation of the resulting cross-coupling
product, which can be converted to the desired hybrid
with the outer six-membered heterocyclic rings.17
A successful example of the synthetic route through
the coupling reaction prior to the outer six-membered
ring formation is demonstrated in the synthesis of BETS
(1b), as shown in Scheme 4. The 1,3-diselenole-2-selone
derivatives (7b, R ) Me and Et) were prepared by
successive treatments of 5 with an equimolar amount of
n-BuLi, selenium, carbon diselenide, and methyl thiocy-
anate (or ethyl thiocyanate). However, it turned out that
analogous conversions of 7b to the 5,6-dihydro-2-sele-
noxo-1,3-diselenolo[2,3-d][1,4]dithiin (12b) or the oxo
derivative (13b) were difficult because of the labile
ethylenedithio-fused 1,3-diselenole-2-selone skeleton.18 As
an alternative approach, 7b was first self-coupled into
the TSF derivative (14b) and then subjected to the
construction of the outer six-membered rings. By this
approach, both methylthio-substituted and ethylthio-
substituted 1,3-diselenole-2-selone derivatives (7b, R )
Me and Et) were successfully converted to BETS (1b).
In the transformation sequence from 7b with the meth-
ylthio group, however, poor solubility of the tosylate (16b)
made its purification difficult and brought inadequate
production and poor reproducibility in the final cycliza-
tion. In contrast, in the transformation sequence of 7b
with ethylthio groups, which can enhance the solubility,
all reactions proceeded smoothly with high yields. The
total yield of BETS from 8 is 16%, which is enhanced by
1 order of magnitude as compared to those of the
preceding synthetic methods.6
To establish an effective synthetic method for the STF
derivative (1c), the two possible synthetic methodologies
from the key intermediate 7c were examined as shown
in Scheme 5. Analogously to the synthesis of BEDT-TTF
(1a ), the route involving the annelation of the outer
heterocyclic ring onto 7c was first tested. The preparation
of 5,6-dihydro-2-thioxo-1,3-selenothia[2,3-d][1,4]dithiin
(12c) from 7c could be carried out without any problem,
but the subsequent coupling reaction to BEDT-STF (1c)
proceeded in a low yield (19%), although the yield was
somewhat improved via the ketone (13c) (32% yield). On
the other hand, the route involving a prior coupling from
7c, as applied above to the synthesis of BETS (1b), gave
a much better result. The direct self-coupling of 7c gave
the STF derivative (14c) only in 20% yield, but the yield
was markedly improved to 85% by the two-step conver-
sion via the ketone 17c. The ensuing reactions for
constructing the outer six-membered rings proceeded
smoothly in high yields. Thus, it is suggested that for
the synthesis of the heterocycle-fused STF system, the
route through the construction of the STF skeleton prior
to the annelation of the heterocyclic ring is advantageous,
(15) (a) Mizuno, M.; Cava, M. P.; Garito, A. F. J . Org. Chem. 1976,
41, 1484-1485. (b) Varma, K. S.; Bury, A.; Harris, N. J .; Underhill, A.
E. Synthesis 1987, 837-838.
(16) Larsen, J .; Lenoir, C. Org. Synth. 1993, 72, 265-272 and
references therein.
(17) Takimiya, K.; Murakami, S.; Kodani, M.; Aso, Y.; Otsubo, T.
Mol. Cryst. Liq. Cryst., in press.
(18) We recently developed the facile synthetic method of 5,6-
dihydro-2-selenoxo-1,3-diselenolo[2,3-d][1,4]dithiin (12b) and recog-
nized that it is relatively labile. Morikami, A.; Takimiya, K.; Aso, Y.;
Otsubo, T. Org. Lett. 1999, 1, 23-25.

Synthesis of Selenium-Containing BEDT-TTF-Type Donors
J . Org. Chem., Vol. 67, No. 12, 2002 4221
Sch em e 5. Syn th esis of BEDT-STF (1c)a
a
Key: (i) n-BuLi, TMEDA, -70 °C; (ii) Se, 0 °C; (iii) CS2, -90 °C; (iv) EtSCN; (v) HCl aq, MeOH-acetone, rt; (vi) TsCl, Et3N, 0 °C; (vii)
NaI, DMF, 80 °C; (viii) P(OMe)3, reflux; (ix) Hg(OAc)2, CHCl3, rt; (x) HCl aq, MeOH-THF, rt.
Sch em e 6. Syn th esis of BEST-TTF (1d )a
synthesized by appropriately choosing the kinds of chal-
cogen reagents in the synthetic protocol in the first one-
pot formation of 1,3-dichalcogenole-2-chalcogenones (7f,g).
The successful syntheses of these complicated BEDT-TTF
derivatives evidently demonstrate the great versatility
of the present method.
Syn th etic Attem p ts for BEDSe-Su bstitu ted Do-
n or s (1h -j). The satisfactory syntheses of all the BEDT-
and BEST-type donors (1a -g) have prompted us to apply
the same approach to the syntheses of the remaining
BEDSe-type counterparts (1h -j). In short, however, the
synthetic strategy failed, and the results are detailed by
the following synthetic investigations of BEDSe-TTF
(1h ). As already mentioned, the construction of the outer
six-membered ring containing two selenium atoms re-
quires the selenium-containing acetylene 6, which was
prepared by a procedure different from that of 5, as
outlined in Scheme 8. Trimethylsilyl (TMS) acetylene (18)
was lithiated with butylllithum, in situ reacted with
elemental selenium, and quenched with 2-iodoethyl tet-
rahydropyranyl ether to give 2-(trimethylethynylseleno)-
ethanol (19). Without purification, it was treated with
aqueous alkaline solution to give the desired 6 in a 74%
two-step yield.
a
Key: (i) n-BuLi, TMEDA, -70 °C; (ii) S, 0 °C; (iii) CS2, -90
°C; (iv) Se, then MeI, 0 °C; (v) HCl aq, MeOH-acetone, rt; (vi)
TsCl, pyridine, 0 °C; (vii) NaI, DMF, 80 °C; (viii) Hg(OAc)2, CHCl3,
rt; (ix) P(OMe)3, reflux.
similar to that of the TSF system. As generally seen for
this type of unsymmetrical TTFs, the STF derivatives
existed as a mixture of E and Z conformational isomers
due to the ready rotation around the central double bond,
being supported by the observation of some nonequiva-
lent signals in 13C NMR spectra of 14c, 15c, and 16c (see
the Experimental Section).
For the synthesis of BEDSe-TTF (1h ), compound 6 was
similarly cyclized to the 1,3-dithiole-2-thione derivative
(7h ) in 59% yield (Scheme 9). The THP protecting group
of 7h was readily removed (81% yield), and the resulting
alcohol (10h ) was treated with tosyl chloride as usual;
however, no desired tosylate (11h ) was obtained, and a
trace amount of diselenide (20) was isolated instead. As
an alternative route, 10h was converted to the bromide
21 (24% yield), which was then treated with sodium
iodide, in expectation of spontaneous annelation to 5,6-
dihydro-2-thioxo-1,3-dithiolo[2,3-d][1,4]diselenin (12h ).
However, no formation of 12h was detected, and the
obtained products were the diselenide 20 (23%) when 21
was treated in DMF at 80 °C and 4-ethylseleno-1,3-
dithiole-2-thione (22) (92%) when treated in refluxing
2-butanone.
Syn t h esis of BE ST-Su b st it u t ed Don or s (1d -g).
The synthesis of BEST-TTF (1d ) was accomplished as
shown in Scheme 6, basically following the same pathway
as that of BEDT-TTF (1a ), except that the initial one-
pot formation reaction of 5 to 7d was quenched with a
mixed reagent of selenium powder and iodomethane
instead of methyl thiocyanate as a source of the selenium
atom in the outer six-membered ring.
The syntheses of BEST-TSF (1e) and BEST-STF (1f
and 1g)19 are outlined in Scheme 7, following the routes
similar to those of BETS (1b) and BEDT-STF (1c). In
BEST-STF, two regioisomers with different positions of
chalcogen atoms regarding the inner-ring double bonds
of the fused rings exist, both of which can be selectively
(19) Abbreviated names of 1f and 1g are designated as BEST-STF-
(t) and BEST-STF(g), respectively, because in 1f, the relative position
of selenium atoms on the inter-ring CdC bond in the dihydro-1,3-
selenothia[1,4]thiaselenin moiety is trans, and, on the other hand, that
in 1g is geminal.
In many attempts to synthesize BEDSe-TSF (1i) and
STF (1j), the formation of the outer six-membered ring
was also unsuccessful. Since it is already known that

4222 J . Org. Chem., Vol. 67, No. 12, 2002
Sch em e 7. Syn th esis of BEST-TSF (1e) a n d BEST-STF (1f,g)a
Takimiya et al.
a
Key: (i) n-BuLi, TMEDA, -70 °C; (ii) S or Se, 0 °C; (iii) CS2 or CSe2, -90 °C; (iv) Se, then EtI, 0 °C; (v) P(OMe)3, reflux; (vi) HCl aq,
MeOH-THF, rt; (vii) TsCl, Et3N, 0 °C; (viii) NaI, DMF, 80 °C.
Sch em e 8. Syn th esis of Selen oa cetylen e 6a
Sch em e 10. Su ggested Rea ction P a th fr om 23
a
Key: (i) n-BuLi, -70 °C; (ii) Se, 0 °C; (iii) 2-iodoethyl
tetrahydropyranyl ether (8), 0 °C; (iv) KOH aq, MeOH, rt.
Sch em e 9. Syn th etic Attem p ts for BEDSe-TTF
(1h )a
synthesize the BEDSe-type donors by this method in-
volving the annelation of the outer six-membered het-
erocyclic ring by an intramolecular transalkylation re-
action on a chalcogen atom.
Con clu sion
We have established a synthetic method of BEDT-TTF
(1a ) and its six selenium variants (1b-g) from the
common starting material 5. The present method is
quite valid and versatile in introducing selenium atoms
at the desired positions of BEDT-TTF framework by
changing the chalcogen reagents (elemental sulfur or
selenium, carbon disulfide or carbon diselenide, alkyl
thiocyanate or selenium powder and alkyl iodide) at the
first one-pot formation of 1,3-dichalcogenole-2-chalco-
genone. In addition, it may be emphasized that in
combination with trialkyl phosphite-induced cross-
coupling reactions, the present method has the potential
of providing synthetic routes to numerous unprecedented
TTF-type donors. However, it has the disadvantage of
being inapplicable to the synthesis of BEDSe-type donors.
In the previous syntheses of BEDSe-TTF7 and BEDSe-
TSF,8 the construction of the outer BEDSe ring was
accomplished by the reaction of either 1,3-dithiole (dis-
elenole)-4,5-diselenium anion or TTF (TSF)-tetrasele-
nium anion with 1,2-dibromoethane, but this ring for-
mation is not straightforward because of the difficult
in situ generation of these selenium anions. In this
connection, we recently developed an improved synthetic
method for BEDSe-TSF (1i) using the deprotection/
realkylation protocol of a protected TSF tetraselenolate.21
a
Key: (i) n-BuLi, TMEDA, -70 °C; (ii) S, 0 °C; (iii) CS2, -90
°C; (iv) Se, then EtI, 0 °C; (v) HCl aq, MeOH-THF, rt; (vi) TsCl,
Et3N, 0 °C; (vii) PBr3, THF, rt; (viii) NaI, DMF, 80 °C; (ix) NaI,
2-butanone, reflux.
2-haloethylselenides tend to decompose via seleniranium
(episelenonium) intermediates,20 we thus speculate that
the failure of the conversion of 21 into 12h can be
rationalized by decomposition of the resulting iodo com-
pound 23 (or the bromo compound 21) via the selenira-
nium salt 25 in preference to the formation of the outer
six-membered ring by transalkylation via the seleninium
salt 24 (Scheme 10). As a result, it is impossible to
(20) (a) Lindgren, B. Acta Chem. Scand. 1973, 27, 726-727. (b)
Lindgren, B. Tetrahedron Lett. 1974, 4347-4350.
(21) Kodani, M.; Takimiya, K.; Aso, Y.; Otsubo, T.; Nakayashiki,
T.; Misaki, Y. Synthesis 2001, 1614-1618.

Synthesis of Selenium-Containing BEDT-TTF-Type Donors
J . Org. Chem., Vol. 67, No. 12, 2002 4223
Ta ble 1. Ha lf-Wa ve Oxid a tion P oten tia lsa of
BEDT-TTF -Typ e Don or s
(200 mL) was slowly added 9 (40 g, 0.23 mol) in THF (30 mL)
at 0 °C, and the resulting reaction mixture was further stirred
for 12 h at room temperature and then poured onto ice-water
(ca. 1 L). The mixture was extracted with dichloromethane
(300 mL × 3), and the extract was washed with water (300
mL × 3) and brine (200 mL × 2), dried (Na2SO4), and
concentrated in vacuo. The oily residue was purified by
distillation (bp 96 °C at 2 mmHg) to give 5 (23 g, 54% yield)
as a colorless oil: 1H NMR δ 1.50-1.80 (m, 6H, CH2), 2.79 (s,
1H, CH), 2.94 (m, 2H, CH3), 3.50-4.10 (m, 4H, CH), 4.67 (m,
1H, CH); 13C NMR δ 19.00, 25.18, 30.22, 34.64, 61.82, 65.15,
73.86, 81.86, 98.60; IR (neat) 2043 cm-1 (CtC). This compound
was thermally unstable and immediately used in the following
step without further purification.
1/2
1/2
donor
E1 (V)
E2 (V)
∆E (V)
BEDT-TTF (1a )
BETS (1b)
0.52
0.69
0.56
0.50
0.67
0.55
0.55
0.62
0.34
0.52
0.88
0.96
0.88
0.87
0.95
0.88
0.87
0.92
0.81
0.88
0.36
0.27
0.32
0.37
0.28
0.33
0.32
0.30
0.47
0.36
BEDT-STF (1c)
BEST-TTF (1d )
BEST-TSF (1e)
BEST-STF(t) (1f)
BEST-STF(g) (1g)
BEDSe-TSF (1i)
TTF
TSF
a
Versus
a Ag/AgCl electrode, in PhCN containing 0.1 M
2-Eth yn ylselen oeth yl Tetr a h yd r op yr a n yl Eth er (6). To
a solution of trimethylsilylacetylene (18) (9.8 g, 0.1 mol) in THF
(200 mL) was slowly added a hexane solution of n-BuLi (1.54
M, 65 mL, 0.1 mol) at -70 °C, and the resulting solution was
stirred for 30 min at the same temperature. To the resulting
lithium acetylide solution was added selenium powder (7.95
g, 0.1 mol) in one portion, and the resulting mixture was
allowed to warm to 0 °C over a period of 2 h. Then, the mixture
was cooled again to -70 °C, and 2-iodoethyl tetrahydropyranyl
ether (8) (28.16 g, 0.11 mol) was added. The mixture was
allowed to warm to room temperature over a period of 2 h and
then concentrated in vacuo. The residue was diluted with
water (250 mL) and extracted with dichloromethane (100 mL
× 3), and the extract was washed with water (100 mL × 2)
and brine (100 mL × 2), dried (Na2SO4), and concentrated in
vacuo. The residual 2-(trimethylethynylseleno)ethyl tetrahy-
dropyranyl ether (19) was dissolved in methanol (250 mL) and
then treated with an aqueous potassium hydroxide solution
(5.5 g in 30 mL of water). The mixture was concentrated, and
the residue was diluted with dichloromethane (250 mL), was
washed with water (100 mL × 2) and brine (100 mL × 2), and
dried (Na2SO4). The solution was passed through a short
column of alumina and concentrated in vacuo to give the crude
product, which was then purified by distillation (bp 88-92 °C
at 10-2 mmHg) to give 6 (17.3 g, 74% yield) as a colorless oil:
1H NMR δ 1.40-1.70 (m, 6H, CH2), 2.66 (s, 1H, CH), 2.88 (m,
2H, CH3), 3.40-3.90 (m, 4H, CH), 4.54 (m, 1H, CH); 13C NMR
δ 19.11, 25.26, 28.26, 30.32, 62.00, 64.90, 66.07, 87.97, 98.63;
IR (neat) 2031 cm-1 (CtC). This compound was not sufficiently
thermally stable to be microanalyzed.
n-Bu4NPF6 as a supporting electrolyte. Pt working and counter
electrodes, scan rate 100 mV/s, 23 °C.
This method nicely complements the present synthetic
method of BEDT-TTF variants. All the selenium variants
of BEDT-TTF thus obtained have strong electron-donat-
ing abilities similar to that of BEDT-TTF itself, which
are estimated on the basis of their half-wave oxidation
potentials as shown in Table 1. Now that these donors
can be readily prepared in practical amounts by the
present method, further investigations on the formation
of their conductive radical cation salts are under way.2
Exp er im en ta l Section
Gen er a l. Melting points are uncorrected. NMR spectra
were obtained in CDCl3 at 400 MHz for 1H and 100 MHz for
13C with TMS as the internal reference. EI-MS spectra were
obtained using an electron impact ionization procedure (70 eV).
A FAB-MS spectrum was recorded using 3-nitrobenzyl alcohol
as a matrix. The molecular ion peaks of selenium-containing
compounds showed a typical selenium isotopic pattern, and
all selenium-containing mass peaks are reported for 80Se. All
chemicals and solvents were reagent grade. All reactions were
carried out under a nitrogen atmosphere with dry solvents.
Column chromatography was carried out with silica gel (63-
210 µm) or aluminum oxide (70-230 µm). Selenium powder
(red)23 and carbon diselenide24 were synthesized according to
the literature procedures.
Gen er a l On e-P ot Syn th etic Meth od of 1,3-Dich a lco-
gen ole-2-ch a lcogen on es (7). 4-Meth ylth io-5-[2-(tetr a h y-
d r op yr a n -2-yloxy)eth ylth io]-1,3-d ith iole-2-th ion e (7a ). To
a mixture of 5 (4.6 g, 25 mmol) and TMEDA (7.4 mL, 49 mmol)
in THF (100 mL) cooled to -70 °C was added a hexane solution
of n-BuLi (1.61 M, 15 mL, 25 mmol), and the solution was
stirred for 30 min to form the lithium acetylide species. Sulfur
(780 mg, 25 mmol) was added in one portion, and the reaction
mixture was warmed to 0 °C over a period of 1 h and stirred
for additional 2 h at 0 °C. The mixture was cooled again to
-90 °C, and then carbon sulfide (1.5 mL, 25 mmol) and methyl
thiocyanate (5.1 mL, 74 mmol) were added. The resulting
mixture was allowed to warm to 0 °C over a period of 2 h and
stirred for an additional 0.5 h at 0 °C. Then, the mixture was
diluted with water (100 mL) and extracted with dichlo-
romethane (100 mL × 3). The extract was washed with brine
(100 mL × 2), dried (Na2SO4), and concentrated in vacuo. The
residue was purified with column chromatography on silica
gel eluted with benzene to afford 7a as a yellow oil (Rf ) 0.4,
6.3 g, 76%): 1H NMR δ 1.48-1.90 (m, 6H, CH2), 2.52 (s, 3H,
CH3), 3.09 (t, J ) 6.4 Hz, 2H, CH2), 3.50-4.00 (m, 4H, CH),
4.63 (m, 1H, CH); 13C NMR δ 18.87, 18.93, 25.02, 30.08, 36.14,
61.85, 65.88, 98.56, 132.02, 139.30, 210.24; IR (neat) 1064 cm-1
(CdS); MS m/z 340 (M+). Anal. Calcd for C11H16O2S5: C, 38.80;
H, 4.74. Found: C, 38.76; H, 4.72.
2-Th iocya n a t oet h yl Tet r a h yd r op yr a n yl E t h er (9). A
mixture of 2-iodoethyl tetrahydropyranyl ether (8)14 (79 g, 0.31
mol) and potassium thiocyanate (45 g, 0.47 mol) in acetone
(1.3 L) was refluxed for 18 h. Precipitated inorganic salts were
filtered off, and the filtrate was concentrated to about one-
third of the original volume, diluted with water (200 mL), and
extracted with dichloromethane (150 mL × 3). The extract was
washed with water (300 mL × 3) and brine (300 mL × 2), dried
(Na2SO4), and concentrated in vacuo to give the crude product,
which was then purified by distillation (bp 115 °C at 3 mmHg)
to give 9 (58.2 g, 85% yield) as a colorless oil: 1H NMR δ 1.50-
1.80 (m, 6H, CH2), 3.19 (m, 2H, CH3), 3.50-4.08 (m, 4H, CH),
4.67 (m, 1H, CH); 13C NMR δ 18.67, 24.90, 29.85, 33.84, 61.77,
64.94, 98.50, 111.85; IR (neat) 2155 cm-1 (SCN); MS m/z 187
(M+). Anal. Calcd for C8H13NO2S: C, 51.31; H, 7.00; N, 7.48.
Found: C, 51.08; H, 7.01; N, 7.38.
2-Eth yn ylth ioeth yl Tetr a h yd r op yr a n yl Eth er (5). To
freshly prepared ethynylmagnesium chloride (0.3 mol) in THF
(22) Some conductive radical cation salts of BEDT-STF (1c) have
been reported in a preliminary report: Mori, H.; Okano, T.; Kamiya,
M.; Haemori, M.; Suzuki, H.; Tnanaka, S.; Tamura, M.; Nishio, Y.;
Kajita, K.; Kodani, M.; Takimiya, K.; Otsubo, T.; Moriyama, H. Synth.
Met. 2001, 120, 979-980.
(23) Cornelissen, J . P.; Haasnoot, J . G.; Reedijk, J .; Faulmann, C.;
Legros, J .-P.; Cassoux, P.; Nigrey, P. J . Inorg. Chim. Acta 1992, 202,
131-139.
(24) (a) Pan, W.-H.; Fackler, J . P., J r. In Inorganic Syntheses;
Fackler, J . P., J r., Ed.; J ohn Wiley & Sons: New York, 1982; Vol. 21,
pp 6-11. (b) Ogura, F.; Takimiya, K. In Organoselenium Chemistry;
A Practical Approach; Back, T. G., Ed.; Oxford University Press: New
York, 1999; pp 258-260.
4-Meth ylth io-5-[2-(tetr ah ydr opyr an -2-yloxy)eth ylth io]-
1,3-d iselen ole-2-selon e (7b, R ) Me): red oil (71% yield
from 5); 1H NMR δ 1.48-1.88 (m, 6H, CH2), 2.55 (s, 3H, CH3),
3.12 (t, J ) 6.6 Hz, 2H, CH2), 3.50-4.10 (m, 4H, CH2), 4.64
(m, 1H, CH); 13C NMR δ 19.24, 20.47, 25.27, 30.36, 37.36,
62.24, 66.16, 98.97, 140.38, 148.20, 206.18; IR (neat) 905 cm-1

4224 J . Org. Chem., Vol. 67, No. 12, 2002
Takimiya et al.
(CdSe); MS m/z 484 (M+). Anal. Calcd for C11H16O2S2Se3: C,
27.45; H, 3.35. Found: C, 27.45; H, 3.35.
to 10a as a yellow solid (Rf ) 0.2 (CH2Cl2), 3.7 g, 85%): 1H
NMR δ 2.43 (s, 1H, OH), 2.54 (s, 3H, CH3), 3.03 (t, J ) 5.4 Hz,
2H, CH2), 3.81 (t, J ) 5.4 Hz, CH2); 13C NMR δ 19.16, 39.72,
60.21, 130.10, 141.98, 210.61; IR (neat) 3000-3700 (OH), 1063
cm-1 (CdS); MS m/z 256 (M+). Anal. Calcd for C6H8OS5: C,
28.10; H, 3.14. Found: C, 28.12; H, 3.15.
4-Eth ylth io-5-(2-h yd r oxyeth ylth io)-1,3-th ia selen ole-2-
th ion e (10c): yellow oil (85% yield from 7c); 1H NMR δ 1.40
(t, J ) 7.4 Hz, 3H, CH3), 2.32 (s, 1H, OH), 2.96 (q, J ) 7.4 Hz,
2H, CH2), 3.01 (t, J ) 5.5 Hz, 2H, CH2), 3.80 (t, J ) 5.5 Hz,
CH2); 13C NMR δ 14.85, 32.20, 39.97, 59.95, 131.21, 144.97,
213.15; IR (neat) 3100-3700 (OH), 1051 cm-1 (CdS); MS m/z
318 (M+). Anal. Calcd for C7H10OS4Se: C, 26.49; H, 3.12.
Found: C, 26.64; H, 3.14.
4-Eth ylth io-5-[2-(tetr a h yd r op yr a n -2-yloxy)eth ylth io]-
1,3-d iselen ole-2-selon e (7b, R ) Et): red oil (73% yield from
5); 1H NMR δ 1.37 (t, J ) 7.3 Hz, 3H, CH3), 1.49-1.88 (m,
6H, CH2), 2.95 (q, J ) 7.3 Hz, 2H, CH2), 3.12 (t, J ) 6.6 Hz,
2H, CH2), 3.50-4.05 (m, 64H, CH2), 4.64 (m, 1H, CH); 13C
NMR δ 14.73, 19.09, 25.13, 30.21, 31.90, 37.33, 62.03, 65.97,
98.76, 143.61, 145.20, 206.37; IR (neat) 907 cm-1 (CdSe); MS
m/z 498 (M+). Anal. Calcd for C12H18O2S2Se3: C, 29.10; H, 3.66.
Found: C, 29.40; H, 3.58.
4-Eth ylth io-5-[2-(tetr a h yd r op yr a n -2-yloxy)eth ylth io]-
1,3-th ia selen ole-2-th ion e (7c): red oil (98% yield from 5);
1H NMR δ 1.38 (t, J ) 7.4 Hz, 3H, CH3), 1.50-1.88 (m, 6H,
CH2), 2.93 (q, J ) 7.4 Hz, 2H, CH2), 3.10 (t, J ) 6.6 Hz, 2H,
CH2), 3.45-4.00 (m, 4H, CH2), 4.64 (m, 1H, CH); 13C NMR δ
14.71, 19.07, 25.16, 30.23, 31.83, 36.31, 62.01, 66.05, 98.72,
133.30, 142.31, 213.15; IR (neat) 1054 cm-1 (CdS); MS m/z
402 (M+). Anal. Calcd for C12H18O2S4Se: C, 35.90; H, 4.52.
Found: C, 36.10; H, 4.66.
4-Met h ylselen o-5-[2-(t et r a h yd r op yr a n -2-yloxy)et h yl-
th io]-1,3-d ith iole-2-th ion e (7d ): yellow oil (80% yield from
5); 1H NMR δ 1.49-1.89 (m, 6H, CH2), 2.42 (s, 3H, CH3), 3.09
(t, J ) 6.6 Hz, 2H, CH2), 3.50-4.00 (m, 4H, CH), 4.64 (m, 1H,
CH); 13C NMR δ 9.61, 19.13, 25.20, 30.28, 36.54, 62.13, 66.07,
98.84, 131.12, 132.55, 212.77; IR (neat) 1067 cm-1 (CdS); MS
m/z 388 (M+). Anal. Calcd for C11H16O2S4Se: C, 34.10; H, 4.16.
Found: C, 34.13; H, 4.14.
4-Meth ylselen o-5-(2-h yd r oxyeth ylth io)-1,3-d ith iole-2-
1
th ion e (10d ): yellow oil (quantitative from 7d ); H NMR δ
2.28 (t, J ) 6.4 Hz, 1H, OH), 2.45 (s, 3H, CH3), 3.02 (t, J ) 5.9
Hz, CH2), 3.81 (dt, J ) 6.4, 5.9 Hz, 2H, CH2); 13C NMR δ 10.00,
40.03, 60.20, 130.01, 133.47, 212.83; IR (neat) 3000-3500
(OH), 1057 cm-1 (CdS); MS m/z 304 (M+). Anal. Calcd for C6H8-
OS4Se: C, 23.76; H, 2.66. Found: C, 23.76; H, 2.61.
4-Eth ylselen o-5-(2-h yd r oxyeth ylselen o)-1,3-d ith iole-2-
th ion e (10h ): yellow oil (81% yield from 7h ); 1H NMR δ 1.53
(t, J ) 7.6 Hz, 3H, CH3), 2.25 (J ) 5.8 Hz, 1H, OH), 3.00 (t, J
) 7.6 Hz, 2H, CH2), 3.10 (t, J ) 6.0 Hz, 2H, CH2), 3.88 (dt, J
) 5.8, 6.0 Hz, 2H, CH2); 13C NMR δ 15.80, 24.83, 34.20, 60.86,
125.85, 130.96, 215.39; IR (neat) 3000-3500 (OH), 1059 cm-1
(CdS); MS m/z 366 (M+). Anal. Calcd for C7H10OS3Se2: C,
23.08; H, 2.77. Found: C, 23.09; H, 2.78.
Gen er a l Syn th etic Meth od for 11. 4-Meth ylth io-5-(2-
tosyloxyeth ylth io)-1,3-d ith iole-2-th ion e (11a ). To a solu-
tion of 10a (3.2 g, 12 mmol) in pyridine (24 mL) was added
tosyl chloride (2.4 g, 37 mmol) at 0 °C. After being stirred for
36 h at 0 °C, the mixture was poured into ice containing 1 M
hydrochloric acid (30 mL). The mixture was extracted with
dichloromethane (100 mL × 3), and the extract was washed
successively with water (100 mL × 2) and brine (50 mL × 2)
and dried (MgSO4). The concentrated extract was purified by
column chromatography on silica gel eluted with dichlo-
romethane to give 10a as yellow oil (Rf ) 0.5, 4.0 g, 80%
yield): 1H NMR δ 2.41 (s, 3H, CH3), 2.44 (s, 3H, CH3), 3.01 (t,
J ) 6.6 Hz, 2H, CH2), 4.16 (t, J ) 6.6 Hz, 2H, CH2), 7.33 (d, J
) 8.3 Hz, 2H, ArH), 7.73 (d, J ) 8.3 Hz, 2H, ArH); 13C NMR
δ 18.88, 21.64, 34.75, 67.47, 127.82, 129.93, 130.22, 132.25,
143.23, 145.32, 210.05; IR (KBr) 1354, 1188 (OdSdO), 1072
cm-1 (CdS); MS m/z 410 (M+). Anal. Calcd for C13H14O3S6: C,
38.03; H, 3.44. Found: C, 37.98; H, 3.38.
4-Eth ylth io-5-(2-tosyloxyeth ylth io)-1,3-th ia selen ole-2-
th ion e (11c): yellow needles from chloroform-hexane (94%
yield from 10c); mp 69-70 °C; 1H NMR δ 1.36 (t, J ) 7.4 Hz,
3H, CH3), 2.47 (s, 3H, CH3), 2.92 (q, J ) 7.4 Hz, 2H, CH2),
3.05 (t, J ) 6.8 Hz, 2H, CH2), 4.21 (t, J ) 6.8 Hz, 2H, CH2),
7.38 (d, J ) 8.2 Hz, 2H, ArH), 7.80 (d, J ) 8.2 Hz, 2H, ArH);
13C NMR δ 14.85, 21.74, 32.05, 34.83, 67.55, 127.97, 129.38,
130.02, 132.46, 145.36, 145.92, 210.65; IR (KBr) 1354, 1171
(OdSdO), 1055 cm-1 (CdS); MS m/z 472 (M+). Anal. Calcd
for C14H16O3S5Se: C, 35.66; H, 3.42. Found: C, 35.43; H, 3.36.
4-Meth ylselen o-5-(2-tosyloxyeth ylth io)-1,3-d ith iole-2-
th ion e (11d ): yellow oil (87% yield from 10d ); 1H NMR δ 2.41
(s, 3H, CH3), 2.47 (s, 3H, CH3), 3.05 (t, J ) 6.8 Hz, 2H, CH2),
4.22 (t, J ) 6.8 Hz, 2H, CH2), 7.38 (d, J ) 8.0 Hz, 2H, ArH),
7.80 (d, J ) 8.0 Hz, 2H, ArH); 13C NMR δ 9.70, 21.73, 30.90,
67.47, 126.23, 127.97, 129.11, 130.02, 132.50, 145.42, 212.32;
IR (KBr) 1361, 1174 (OdSdO), 1063 cm-1 (CdS); MS m/z 458
(M+). Anal. Calcd for C13H14O3S5Se: C, 34.13; H, 3.08. Found:
C, 34.00; H, 3.05.
4-Eth ylselen o-5-[2-(tetr ah ydr opyr an -2-yloxy)eth ylth io]-
1
1,3-d iselen ole-2-selon e (7e): red oil (82% yield from 5); H
NMR δ 1.51 (t, J ) 7.4 Hz, 3H, CH3), 1.5-1.9 (m, 6H, CH2),
3.01 (q, J ) 7.4 Hz, 2H, CH2), 3.13 (t, J ) 6.6 Hz, 2H, CH2),
3.45-4.00 (m, 4H, CH2), 4.64 (m, 1H, CH); 13C NMR δ 15.56,
18.97, 24.84, 25.02, 30.09, 37.46, 61.86, 65.81, 98.58, 136.06,
143.22, 208.70; IR (neat) 909 cm-1 (CdSe); MS m/z 546 (M+).
Anal. Calcd for C12H18O2SSe4: C, 26.53; H, 3.53. Found: C,
26.73; H, 3.52.
5-Eth ylselen o-4-[2-(tetr ah ydr opyr an -2-yloxy)eth ylth io]-
1,3-th ia selen ole-2-selon e (7f): red oil (73% yield from 5);
1H NMR δ 1.51 (t, J ) 7.5 Hz, 3H, CH3), 1.49-1.86 (m, 6H,
CH2), 3.00 (q, J ) 7.5 Hz, 2H, CH2), 3.13 (t, J ) 6.4 Hz, 2H,
CH2), 3.45-4.05 (m, 4H, CH2), 4.64 (m, 1H, CH); 13C NMR δ
15.71, 19.15, 24.36, 25.15, 30.23, 37.68, 62.13, 66.00, 98.88,
130.84, 144.76, 207.24; IR (neat) 932 cm-1 (CdSe); MS m/z
498 (M+). Anal. Calcd for C12H18O2S2Se3: C, 29.10; H, 3.66.
Found C, 29.13; H, 3.65.
4-Eth ylselen o-5-[2-(tetr ah ydr opyr an -2-yloxy)eth ylth io]-
1,3-th ia selen ole-2-th ion e (7g): yellow oil (88% yield from
5); 1H NMR δ 1.52 (t, J ) 7.5 Hz, 3H, CH3), 1.50-1.85 (m,
6H, CH2), 2.98 (q, J ) 7.5 Hz, 2H, CH2), 3.09 (t, J ) 6.4 Hz,
2H, CH2), 3.48-4.00 (m, 4H, CH2), 4.64 (m, 1H, CH); 13C NMR
δ 15.73, 19.23, 24.89, 25.30, 30.40, 36.67, 62.22, 66.19, 98.95,
133.76, 134.07, 215.63; IR (neat) 1055 cm-1 (CdS); MS m/z
450 (M+). Anal. Calcd for C12H18O2S3Se2: C, 32.14; H, 4.05.
Found: C, 32.11; H, 4.07.
4-Eth ylselen o-5-[2-(tetr a h yd r op yr a n -2-yloxy)eth ylse-
len o]-1,3-d ith iole-2-th ion e (7h ). This compound was simi-
larly prepared using 2-ethynylselenoethyl tetrahydropyranyl
ether (6) instead of 5: yellow oil (59% yield from 6); 1H NMR
δ 1.51 (t, J ) 7.6 Hz, 3H, CH3), 1.45-1.80 (m, 6H, CH2), 2.98
(q, J ) 7.5 Hz, 2H, CH2), 3.16 (t, J ) 6.7 Hz, 2H, CH2), 3.45-
4.10 (m, 4H, CH2), 4.64 (m, 1H, CH); 13C NMR δ 15.71, 19.11,
24.47, 25.19, 30.19, 30.26, 62.11, 66.53, 98.72, 128.01, 128.29,
215.27; IR (neat) 1063 cm-1 (CdS); MS m/z 450 (M+). Anal.
Calcd for C12H18O2S3Se2: C, 32.14; H, 4.05. Found: C, 32.08;
H, 4.12.
Gen er a l Syn th etic Meth od for 10. 4-Meth ylth io-5-(2-
h yd r oxyeth ylth io)-1,3-d ith iole-2-th ion e (10a ). A mixture
of 7a (5.8 g, 17 mmol), hydrochloric acid (1 M, 20 mL),
methanol (30 mL), and acetone (30 mL) was stirred at room
temperature for 24 h. The mixture was diluted with dichlo-
romethane (300 mL), and the solution was washed with water
(100 mL × 3) and brine (100 mL × 2), dried (MgSO4), and then
concentrated. The residue was purified by column chromatog-
raphy (silica gel; eluent, 9:1 v/v dichloromethane/ethyl acetate)
Gen er al Syn th etic Meth od for 12. 5,6-Dih ydr o-2-th ioxo-
1,3-d ith iolo[2,3-d ][1,4]d ith iin (12a ). A mixture of 11a (0.40
g, 0.96 mmol) and sodium iodide (0.29 g, 1.9 mmol) in DMF (4
mL) was heated at 95 °C for 20 h. The mixture was then
diluted with water (30 mL) and extracted with carbon disulfide
(50 mL × 3), and the extract was successively washed with
water (50 mL × 3) and brine (50 mL × 2) and finally dried
(MgSO4). Column chromatography of the concentrated extract
on silica gel eluted with carbon disulfide gave 12a as yellow

Synthesis of Selenium-Containing BEDT-TTF-Type Donors
J . Org. Chem., Vol. 67, No. 12, 2002 4225
needles (0.14 g, 67% yield): mp 121-122 °C (recrystallization
2,6(7)-Bis(eth ylselen o)-3,7(6)-bis[2-(tetr a h yd r op yr a n -
2-yloxy)eth ylth io]-tetr aselen afu lvalen e (14e): red oil (83%
yield from 7e); 1H NMR δ 1.48 (t, J ) 7.4 Hz, 6H, CH3), 1.45-
1.90 (m, 12H, CH2), 2.95 (q, J ) 7.4 Hz, 4H, CH2), 3.04 (t, J )
6.8 Hz, 2H, CH2), 3.05 (t, J ) 6.6 Hz, 2H, CH2), 3.45-3.98 (m,
8H, CH2), 4.65 (m, 2H, CH); 13C NMR δ 15.91, 19.22, 24.64,
25.29, 30.36, 37.07, 62.11, 66.21, 98.82, 108.70, 108.75, 122.43
and 122.70, 128.40 and 128.66; MS (FAB) m/z 932 (M+). Anal.
Calcd for C24H36O4S2Se6: C, 31.12; H, 3.92. Found: C, 30.84;
H, 3.77.
1
from chloroform; lit.15b 119-121 °C); H NMR δ 3.38 (s, 4H,
CH2); MS m/z 224 (M+); IR (KBr) 1061 cm-1 (CdS).
5,6-D ih y d r o -2-t h io x o -1,3-t h ia s e le n o lo [2,3-d ][1,4]-
d ith iin (12c): yellow needles from carbon disulfide-hexane
(65% yield from 11c); mp 122 °C; 1H NMR δ 3.41 (s, 4H, CH2);
13C NMR δ 29.95, 30.88, 122.58, 124.63, 209.18; IR (KBr) 1020
cm-1 (CdS); MS m/z 272 (M+). Anal. Calcd for C5H4S4Se: C,
22.14; H, 1.49. Found: C, 22.32; H, 1.56.
5 ,6 -D i h y d r o -2 -t h i o x o -1 ,3 -d i t h i o l o [ 2 ,3 -d ] [ 1 ,4 ] -
th ia selen in (12d ): yellow needles from chloroform-hexane
(52% yield from 11d ); mp 124-125 °C; 1H NMR δ 3.33 (m,
2H, CH2), 3.52 (m, 2H, CH2); 13C NMR δ 25.17, 31.50, 118.38,
126.61, 210.33; IR (KBr) 1059 cm-1 (CdS); MS m/z 272 (M+).
Anal. Calcd for C5H4S4Se: C, 22.14; H, 1.49. Found: C, 22.12;
H, 1.46.
Gen er a l Syn th etic Meth od for 13. 5,6-Dih yd r o-2-oxo-
1,3-d ith iolo[2,3-d ][1,4]th ia selen in (13d ). A mixture of 12d
(0.59 g, 2.2 mmol) and mercury acetate (0.17 g, 5.5 mmol) in
chloroform (44 mL) was stirred for 8 h. The resulting white
solid was filtered off and washed with chloroform (10 mL ×
3), and the combined filtrate was washed with water (50 mL
× 3) and brine (50 mL × 3) and dried (MgSO4). Evaporation
of the solvent gave a pale yellow solid, which was then purified
by recrystallization from chloroform-hexane to give 13d as
pale yellow needles (533 mg, 95%): mp 119-120 °C; 1H NMR
δ 3.31 (m, 2H, CH2), 3.56 (m, 2H, CH2); 13C NMR δ 27.06,
32.37, 109.69, 117.12, 191.00; IR (KBr) 1613 cm-1 (CdO); MS
m/z 256 (M+). Anal. Calcd for C5H4OS3Se: C, 23.53; H, 1.58.
Found: C, 23.56; H, 1.52.
5,6-Dih yd r o-2-oxo-1,3-t h ia selen olo[2,3-d ][1,4]d it h iin
(13c): colorless fine crystals from carbon disulfide-hexane
(83% yield from 12c); mp 110 °C (lit.9 110 °C); 1H NMR δ 3.43
(s, 4H, CH2); 13C NMR δ 32.77, 34.06 100.52, 118.40, 189.65;
IR (KBr) 1635 cm-1 (CdO); MS m/z 256 (M+). Anal. Calcd for
C5H4OS3Se: C, 23.53; H, 1.58. Found: C, 23.43; H, 1.62.
Gen er a l Syn th etic Meth od for 14. 2,6(7)-Bis(m eth -
ylth io)-3,7(6)-bis[2-(tetr a h yd r op yr a n -2-yloxy)eth ylth io]-
tetr a selen a fu lva len e (14b, R ) Me). To a refluxing solution
of 7b (R ) Me, 2.0 g, 4.2 mmol) in benzene (20 mL) was added
trimethyl phosphite (2.0 mL, 17 mol), and the resulting
mixture was refluxed for 1 h. Evaporation of the solvent and
excess trimethyl phosphite gave an oily residue, which was
purified by column chromatography on silica gel with dichlo-
romethane-ethyl acetate (9:1, v/v) as an eluent to give 14b
(R ) Me) as a red oil (Rf ) 0.3, 1.3 g, 77%): 1H NMR δ 1.48-
1.90 (m, 12H, CH2), 2.460 and 2.462 (s, 6H, CH3), 3.056 (t, J
) 7.0 Hz, 2H, CH2), 3.063 (t, J ) 6.2 Hz, 2H, CH2), 3.48-3.98
(m, 8H, CH2), 4.65 (m, 2H, CH); 13C NMR δ 19.25, 20.52, 25.34,
30.40, 37.00, 62.15, 66.30 and 66.32, 98.88, 107.39 and 107.45,
127.49 and 127.63, 133.27 and 133.39; MS (FAB) m/z 808 (M+).
Anal. Calcd for C22H32O4S4Se4: C, 32.84; H, 4.01. Found: C,
32.80; H, 4.00.
2,6(7)-Bis(et h ylt h io)-3,7(6)-b is[2-(t et r a h yd r op yr a n -2-
yloxy)eth ylth io]-tetr a selen a fu lva len e (14b, R ) Et): red
oil (60% yield from 7b, R ) Et); 1H NMR δ 1.33 (t, J ) 7.3 Hz,
6H, CH3), 1.45-1.90 (m, 12H, CH2), 2.88 (q, J ) 7.3 Hz, 4H,
CH2), 3.062 (t, J ) 6.8 Hz, 2H, CH2), 3.068 (t, J ) 6.6 Hz, 2H,
CH2), 3.45-3.90 (m, 8H, CH2), 4.65 (m, 2H, CH); 13C NMR δ
14.99, 19.23, 23.31, 30.39, 31.72, 37.01 and 37.02, 62.12, 66.28,
98.85, 106.88, 129.89 and 129.95, 131.29 and 131.34; MS (FAB)
m/z 836 (M+). Anal. Calcd for C24H36O4S4Se4: C, 34.62; H, 4.36.
Found: C, 34.70; H, 4.36.
3,7-Bis(eth ylselen o)-2,6-bis[2-(tetr ah ydr opyr an -2-yloxy)-
eth ylth io]-d iselen a d ith ia fu lva len e (14f): red oil (50% yield
1
from 7f); H NMR δ 1.48 (t, J ) 7.6 Hz, 6H, CH3), 1.46-1.89
(m, 12H, CH2), 2.956 and 2.964 (q, J ) 7.6 Hz, 4H, CH2), 3.02
(m, 4H, CH2), 3.48-3.96 (m, 8H, CH2), 4.65 (m, 2H, CH); 13C
NMR δ 15.91, 19.29, 23.74, 25.35, 30.44, 37.08 and 37.15,
62.20, 66.30, 98.95, 110.44 and 111.05, 122.13 and 123.06,
125.36 and 126.03; MS (FAB,) m/z 836 (M+). Anal. Calcd for
C
24H36O4S4Se4: C, 34.62; H, 4.36. Found: C, 34.59; H, 4.37.
2,6-Bis(eth ylselen o)-3,7-bis[2-(tetr ah ydr opyr an -2-yloxy)-
eth ylth io]-d iselen a d ith ia fu lva len e (14g): red oil (67%
yield from 7g); 1H NMR δ 1.48 (t, J ) 7.6 Hz, 6H, CH3), 1.48-
1.80 (m, 12H, CH2), 2.91 (q, J ) 7.6 Hz, 4H, CH2), 3.05 (m,
4H, CH2), 3.48-3.90 (m, 8H, CH2), 4.65 (m, 2H, CH); 13C NMR
δ 15.91, 19.18, 24.49 and 24,53, 25.27, 30.35, 35.90 and 35.93,
62.04 and 62.07, 66.21, 98.76, 109.54 and 110.37, 119.20 and
120.26, 127.72 and 129.04; MS (FAB) m/z 836 (M+). Anal.
Calcd for C24H36O4S4Se4: C, 34.62; H, 4.36. Found: C, 34.44;
H, 4.34.
Gen er a l Syn th etic Meth od for 15. 2,6(7)-Bis(m eth -
ylt h io)-3,7(6)-b is(2-h yd r oxye t h ylt h io)-t e t r a se le n a fu l-
va len e (15b R ) Me): A mixture of 14b (R ) Me, 1.3 g, 1.6
mmol), hydrochloric acid (1.0 M, 4.0 mL), methanol (30 mL),
and THF (30 mL) was stirred at room temperature for 24 h.
The mixture was diluted with water (50 mL) and extracted
with dichloromethane (50 mL × 3). The extract was washed
with water (50 mL × 3) and brine (50 mL × 3) and dried
(MgSO4). Evaporation of the solvent gave crude 15b (R ) Me),
which was purified by silica gel column chromatography eluted
with dichloromethane-ethyl acetate (9:1, v/v) to give a red oil
(Rf ) 0.1, 0.74 g, 72% yield): 1H NMR δ 2.50 (s, 3H, CH3),
2.62 (s, 2H, OH), 2.96 (t, J ) 5.6 Hz, 4H, CH2), 3.76 (t, J ) 5.6
Hz, 4H, CH2); 13C NMR δ 20.72, 40.19, 59.97, 107.22, 125.10
and 125.30, 136.53 and 136.70; IR (KBr) 3300 cm-1 (OH); MS
m/z 640 (M+). Anal. Calcd for C12H16O2S4Se4: C, 22.65; H, 2.53.
Found: C, 22.64; H, 2.53.
2,6(7)-Bis(et h ylt h io)-3,7(6)-b is(2-h yd r oxyet h ylt h io)-
tetr a selen a fu lva len e (15b, R ) Et): pink plates from
chloroform-hexane (94% yield from 14b, R ) Et); mp 84-85
1
°C; H NMR δ 1.35 (t, J ) 7.4 Hz, 6H, CH3), 2.46, (t, J ) 6.3
Hz, 2H, OH), 2.92 (t, J ) 7.4 Hz, 4H, CH2), 2.97 (t, J ) 5.6
Hz, 4H, CH2), 3.75 (dt, J ) 6.3, 5.6 Hz, 4H, CH2); 13C NMR δ
15.08, 32.15, 40.35, 59.88, 106.87, 127.18 and 127.32, 135.04
and 135.17; IR (KBr) 3400 cm-1 (OH); MS m/z 668 (M+). Anal.
Calcd for C14H20O2S4Se4: C, 25.31; H, 3.03. Found: C, 25.04;
H, 2.80.
2,6(7)-Bis(et h ylt h io)-3,7(6)-b is(2-h yd r oxyet h ylt h io)-
diselen adith iafu lvalen e (15c): red powder from chloroform-
1
hexane (89% yield from 14c); mp 79-81 °C; H NMR δ 1.353
and 1.354 (t, J ) 7.5 Hz, 6H, CH3), 2.42-2.49 (m, 2H, OH),
2.885 and 2.889 (q, J ) 7.5 Hz, 4H, CH2), 2.95-3.10 (m, 4H,
CH2), 3.71-3.78 (m, 4H, CH2); 13C NMR δ 15.13, 32.10 and
32.16, 39.34, 59.98 and 60.04, 108.30 and 109.11, 126.07 and
127.33, 131.30 and 132.23; IR (KBr) 3400 cm-1 (OH); MS m/z
572 (M+). Anal. Calcd for C14H20O2S6Se2: C, 29.47; H. 3.53.
Found: C, 29.48; H, 3.42.
2,6(7)-Bis(et h ylt h io)-3,7(6)-b is[2-(t et r a h yd r op yr a n -2-
yloxy)eth ylth io]-d iselen a d ith ia fu lva len e (14c): yellow oil
1
(Rf ) 0.2, 0.88 g, 91% from 17c); H NMR δ 1.329 and 1.331
2,6(7)-Bis(eth ylselen o)-3,7(6)-bis(2-h yd r oxyeth ylth io)-
tetr aselen afu lvalen e (15e): red plate from dichloromethane-
(t, J ) 7.5 Hz, 6H, CH3), 1.50-1.85 (m, 12H, CH2), 2.846 and
2.849 (q, J ) 7.5 Hz, 4H, CH2), 3.05-3.09 (m, 4H, CH2), 3.48-
3.98 (m, 8H, CH2), 4.65 (m, 2H, CH); 13C NMR δ 15.04 and
15.07, 19.25 and 19.27, 25.36, 30.44, 31.74 and 31.79, 35.86
and 35.89, 62.16 and 62.19, 66.36, 98.88 and 98.91, 108.38 and
109.13, 127.99 and 128.57, 128.88 and 129.77; MS m/z 740
(M+). Anal. Calcd for C24H36O4S6Se2: C, 39.02; H, 4.91.
Found: C, 38.85; H, 4.96.
1
hexane (80% yield from 14e); mp 89-90 °C; H NMR δ 1.50
(t, J ) 7.5 Hz, 6H, CH3), 2.54, (t, J ) 5.3 Hz, 2H, OH), 2.95 (t,
J ) 5.3 Hz, 4H, CH2), 3.00 (q, J ) 7.5 Hz, 4H, CH2), 3.75 (q,
J ) 5.3 Hz, 4H, CH2); 13C NMR δ 16.00, 25.33, 40.43, 59.71,
108.73, 126.17 and 126.45, 126.50 and 126.77; IR (KBr) 3400
cm-1 (OH); MS m/z 764 (M+). Anal. Calcd for C14H20O2S2Se6:
C, 22.18; H, 2.66. Found: C, 21.98; H, 2.56.

4226 J . Org. Chem., Vol. 67, No. 12, 2002
Takimiya et al.
3,7-Bis(eth ylselen o)-2,6-bis(2-h yd r oxyeth ylth io)-d isel-
en a d ith ia fu lva len e (15f): red powder from chloroform-
hexane (92% yield from 14f); mp 110-112 °C; 1H NMR δ 1.50
(t, J ) 7.6 Hz, 6H, CH3), 2.40 (t, J ) 6.8 Hz, 2H, OH), 2.93 (t,
J ) 6.6 Hz, 4H, CH2), 3.01 (q, J ) 7.6 Hz, 4H, CH2), 3.74 (dt,
J ) 6.8, 6.6 Hz, 4H, CH2); 13C NMR δ 15.91, 24.29, 40.34,
59.71, 110.51, 123.81, 125.88; IR (KBr) 3400 cm-1 (OH); MS
m/z 668 (M+). Anal. Calcd for C14H20O2S4Se4: C, 25.31; H, 3.03.
Found: C, 25.30; H, 3.01.
2,6-Bis(eth ylselen o)-3,7-bis(2-h yd r oxyeth ylth io)-d isel-
en a d ith ia fu lva len e (15g): red powder from chloroform-
hexane (77% yield from 14g); mp 68-70 °C; 1H NMR δ 1.503
and 1.505 (t, J ) 7.6 Hz, 6H, CH3), 2.51 (s, 2H, OH), 2.951
and 2.955 (q, J ) 7.6 Hz, 4H, CH2), 2.96 (t, J ) 5.6 Hz, 4H,
CH2), 3.73 (t, J ) 5.6 Hz, 4H, CH2); 13C NMR δ 15.95, 25.07
and 25.11, 39.28, 59.80 and 59.85, 109.47 and 110.39, 122.33
and 123,40, 125.98 and 127.30; IR (KBr) 3300 cm-1 (OH); MS
m/z 668 (M+). Anal. Calcd for C14H20O2S4Se4: C, 25.31; H, 3.03.
Found: C, 25.30; H, 3.00.
Gen er a l Syn th etic Meth od for 16. 2,6(7)-Bis(m eth -
y lt h i o )-3,7(6)-b i s (2-t o s y lo x y e t h y lt h i o )t e t r a s e le n a -
fu lva len e (16b, R ) Me). To a solution of 15b (R ) Me, 0.21
g, 0.33 mmol) in pyridine (5 mL) was added tosyl chloride (0.19
g, 2.0 mmol) at 0 °C. The mixture was stirred for 12 h, and
then poured onto a mixture of ice and hydrochloric acid (1 M,
10 mL). The organic layer was separated, and the aqueous
layer was extracted with dichloromethane (50 mL × 3). The
combined dichloromethane solution was washed successively
with hydrochloric acid (1 M, 50 mL × 2), water (50 mL × 3),
and brine (50 mL × 2) and dried (MgSO4). Evaporation of the
solvent gave crude 16b (R ) Me), which was purified by
column chromatography on silica gel eluted with dichlo-
romethane followed by recrystallization from dichloromethane-
hexane (1:1, v/v) as an orange solid (0.19 g, 61%): mp 117-
119 °C (from dichloromethane-methanol); 1H NMR δ 2.45 (s,
6H, CH3), 2.46 (s, 6H, CH3), 3.03 (t, J ) 7.0 Hz, 4H, CH2),
4.20 (t, J ) 7.0 Hz, 4H, CH2), 7.36 (d, J ) 8.3 Hz, 4H, ArH),
7.80 (d, J ) 8.3 Hz, 4H, ArH); IR (KBr) 1363, 1175 cm-1 (Od
SdO). Anal. Calcd for C26H28O6S6Se4: C, 33.06; H, 2.99.
Found: C, 33.10; H, 2.93.
3,7-Bis(eth ylselen o)-2,6-bis(2-tosyloxyeth ylth io)d isel-
en a d it h ia fu lva len e (16f): pink powder from dichloro-
methane-hexane (72% yield from 15f); mp 134-136 °C; 1H
NMR δ 1.43-1.46 (m, 6H, CH3), 2.46 (s, 6H, CH3), 2.92-3.01
(m, 8H, CH2), 4.17-4.21 (m, 4H, CH2), 7.36 (d, J ) 8.3 Hz,
4H, ArH), 7.80 (d, J ) 8.3 Hz, 4H, ArH); 13C NMR δ 15.96,
21.75, 24.04, 35.48, 67.85, 107.04, 122.88, 125.94, 128.03,
130.00, 132,80, 145.14; IR (KBr) 1348, 1177 cm-1 (OdSdO).
Anal. Calcd for C28H32O6S6Se4: C, 34.57; H, 3.32. Found: C,
34.53; H, 3.29.
2,6-Bis(eth ylselen o)-3,7-bis(2-tosyloxyeth ylth io)d isel-
en a d it h ia fu lva len e (16g): pink powder from dichloro-
1
methane-hexane (76% yield from 15g); mp 107-109 °C; H
NMR δ 1.450 and 1.452 (t, J ) 7.4 Hz, 6H, CH3), 2.45 (s, 6H,
CH3), 2.89 (q, J ) 7.4 Hz, 4H, CH2), 3.024 and 3.029 (t, J )
7.3 Hz, 4H, CH2), 4.19 (t, J ) 7.3 Hz, 4H, CH2); 7.35 (d, 4H, J
) 8.5 Hz, ArH), 7.80 (d, 4H, J ) 8.5 Hz, ArH); 13C NMR δ
16.04, 21.75, 24.92, 34.47 and 34.53, 67.97, 109.12 and 110.09,
122.65 and 123.78, 125.15, 128.02, 129.99, 132,84, 145.10; IR
(KBr) 1348, 1177 cm-1 (OdSdO). Anal. Calcd for C28H32O6S6-
Se4: C, 34.57; H, 3.32. Found: C, 34.52; H, 3.26.
4-Eth ylth io-5-[2-(tetr a h yd r op yr a n -2-yloxy)eth ylth io]-
1,3-th ia selen ol-2-on e (17c). Transchalcogenation reaction of
7c to 17c was carried out in a manner similar to that described
for the conversion of 12d to 13d : colorless oil (93% yield); 1H
NMR δ 1.30 (t, J ) 7.4 Hz, 3H, CH3), 1.50-1.85 (m, 6H, CH2),
2.91 (q, J ) 7.4 Hz, 2H, CH2), 3.07 (t, J ) 6.8 Hz, 2H, CH2),
3.45-3.97 (m, 4H, CH2), 4.64 (m, 1H, CH); 13C NMR δ 14.65,
19.00, 25.10, 30.17, 31.83, 36.08, 61.85, 65.94, 98.58, 124.66,
132.72, 188.46; IR (neat) 1700 cm-1 (CdO); MS m/z 386 (M+).
Anal. Calcd for C12H18O3S3Se: C, 37.40; H, 4.71. Found: C,
37.68; H, 4.76.
Bis(eth ylen ed ith io)tetr a selen a fu lva len e (BETS, 1b). A
mixture of 16b (R ) Et, 102 mg, 0.11 mmol) and sodium iodide
(63 mg, 4.2 mmol) in DMF (0.9 mL) was stirred at 80 °C for
4.5 h. The reaction mixture was cooled, diluted with water (30
mL), and then extracted with carbon disulfide (30 mL × 3).
The extract was washed with water (50 mL × 2) and brine
(50 mL × 2) and dried (MgSO4). Evaporation of the solvent
gave a red solid, which was purified by recrystallization from
carbon disulfide-hexane to afford reddish purple needles (97%
2,6(7)-Bis(eth ylth io)-3,7(6)-bis(2-tosyloxyeth ylth io)tet-
r a selen a fu lva len e (16b, R ) Et): pale red solid from
chloroform-hexane (87% yield from 15b, R ) Et); mp 118-
1
yield): mp 269-270 °C (lit.5b 275 °C dec.); H NMR δ 3.30 (s,
8H, CH2); MS m/z 576 (M+).
1
Bis(et h ylen ed it h io)d iselen a d it h ia fu lva len e (BE DT-
STF , 1c). Three approaches shown in Scheme 5 were exam-
ined, and the best result was obtained from 16c using the same
procedure described for the synthesis of 1b from 16b: red
needles from chlorobenzene (82% yield); mp 250 °C (lit.11 250
°C dec.); 1H NMR δ 3.28 (s, 8H, CH2); MS m/z 480 (M+). Anal.
Calcd for C10H8S6Se2: C, 25.10; H, 1.69. Found: C, 25.28; H,
1.69.
Bis(eth ylen eselen oth io)tetr ath iafu lvalen e (BEST-TTF,
1d ). This compound was obtained by trimethyl phosphite-
induced homocoupling of 13d : orange needles from chloroben-
zene (87% yield); mp 260 °C dec.; 1H NMR δ 3.18 (m, 4H, CH2),
3.37 (m, 4H, CH2); MS m/z 480 (M+). Anal. Calcd for C10H8S6-
Se2: C, 25.10; H, 1.69. Found: C, 25.19; H, 1.68.
Bis(eth ylen eselen oth io)tetr a selen a fu lva len e (BEST-
TSF , 1e). Compounds 1e-g were obtained from 16e-g,
respectively, by using the same procedure described for the
synthesis of 1b. 1e: purple needles from chlorobenzene (56%
yield from 16e); mp 245 °C dec.; 1H NMR δ 3.19 (m, 4H, CH2),
3.40 (m, 4H, CH2); MS m/z 672 (M+). Anal. Calcd for C10H8S2-
Se6: C, 18.03; H, 1.21. Found: C, 18.07; H, 1.29.
120 °C; H NMR δ 1.29 (t, J ) 7.4 Hz, 6H, CH3), 2.46 (s, 6H,
CH3), 2.86 (q, J ) 7.4 Hz, 4H, CH2), 3.04 (t, J ) 7.0 Hz, 4H,
CH2), 4.19 (t, J ) 7.0 Hz, 4H, CH2), 7.36 (d, J ) 8.1 Hz, 4H,
ArH), 7.80 (d, J ) 8.1 Hz, 4H, ArH); 13C NMR δ 14.05 and
15.04, 21.66 and 22.55, 31.89 and 31.91, 35.32 and 35.37, 67.79
and 67.80, 106.87, 126.23 and 126.38, 127.90, 129.91, 132.64,
135.19 and 135.27, 145.02; IR (KBr) 1350, 1177 cm-1 (OdSd
O). Anal. Calcd for C28H32O6S6Se4: C, 34.57; H, 3.32. Found:
C, 34.35; H, 3.21.
2,6(7)-Bis(eth ylth io)-3,7(6)-bis(2-tosyloxyeth ylth io)d is-
elen a d it h ia fu lva len e (16c): pink powder from dichlo-
romethane-hexane (91% yield from 15c); mp 110-112 °C; 1H
NMR δ 1.293 and 1.297 (t, J ) 7.5 Hz, 6H, CH3), 2.46 (s, 6H,
CH3), 2.83 (q, J ) 7.5 Hz, 4H, CH2), 3.037 (t, J ) 7.2 Hz, 2H,
CH2), 3.044 (t, J ) 7.1 Hz, 2H, CH2), 4.186 (t, J ) 7.1 Hz, 2H,
CH2), 4.190 (t, J ) 7.1 Hz, 2H, CH2), 7.35 (d, 4H, J ) 8.1 Hz,
ArH), 7.80 (d, 4H, J ) 8.2 Hz, ArH); 13C NMR δ 15.14, 21.74,
31.94 and 31.98, 34.32 and 34.38, 67.97, 108.40 and 109.24,
125.38, 127.99, 129.97, 131.41 and 132,36, 132.79, 145.10; IR
(KBr) 1348, 1177 cm-1 (OdSdO). Anal. Calcd for C28H32O6S8-
Se2: C, 38.26; H, 3.67. Found: C, 38.15; H, 3.56.
Bis(eth ylen eselen oth io)diselen adith iafu lvalen e (BEST-
STF (t), 1f): red needles from carbon disulfide-hexane (55%
yield from 16f); mp 240 °C dec.; 1H NMR δ 3.19 (m, 4H, CH2),
3.39 (m, 4H, CH2); MS m/z 576 (M+). Anal. Calcd for C10H8S4-
Se4: C, 20.99; H, 1.41. Found: C, 20.99; H, 1.43.
Bis(eth ylen eselen oth io)diselen adith iafu lvalen e (BEST-
STF (g), 1g): red needles from carbon disulfide-hexane (98%
yield from 16g); mp 250 °C dec.; 1H NMR δ 3.19 (m, 4H, CH2),
3.37 (m, 4H, CH2); MS m/z 576 (M+). Anal. Calcd for C10H8S4-
Se4: C, 20.99; H, 1.41. Found: C, 20.93; H, 1.49.
2,6(7)-Bis(eth ylselen o)-3,7(6)-bis(2-tosyloxyeth ylth io)-
t et r a selen a fu lva len e (16e): brown solid from dichloro-
1
methane-hexane (86% yield from 15e); mp 147-148 °C; H
NMR δ 1.44 (t, J ) 7.2 Hz, 6H, CH3), 2.46 (s, 6H, CH3), 2.93
(q, J ) 7.2 Hz, 4H, CH2), 3.02 (t, J ) 7.0 Hz, 4H, CH2), 4.20 (t,
J ) 7.0 Hz, 4H, CH2), 7.36 (d, J ) 8.2 Hz, 4H, ArH), 7.80 (d,
J ) 8.2 Hz, 4H, ArH); 13C NMR δ 16.02, 21.77, 25.05, 35.49,
67.87, 108.74, 125.36, 126.69, 128.03, 130.00, 132.73, 145.12;
IR (KBr) 1348, 1177 cm-1 (OdSdO). Anal. Calcd for C28H32O6S4-
Se6: C, 31.53; H, 3.02. Found: C, 31.55; H, 3.00.

Synthesis of Selenium-Containing BEDT-TTF-Type Donors
J . Org. Chem., Vol. 67, No. 12, 2002 4227
4-E t h ylselen o-5-(2-b r om oet h ylselen o)-1,3-d it h iole-2-
th ion e (21). To a solution of 10h (433 mg, 1.18 mmol) in THF
(10 mL) was slowly added phosphorus tribromide (0.14 mL,
1.42 mmol) at -10 °C, and the resulting mixture was stirred
for 5 h at room temperature. The reaction mixture was diluted
with water (50 mL) and extracted with dichloromethane (100
mL × 3). The extract was washed with water (200 mL × 3)
and brime (200 mL × 3), dried (MgSO4), and concentrated in
vacuo. The resulting residue was purified with a silica gel
column chromatography eluted with dichloromethane to give
the bromide (21) (Rf ) 0.85, 119 mg, 24% yield) as a yellow
oil: 1H NMR δ 1.53 (t, J ) 7.6 Hz, 3H, CH3), 3.00 (t, J ) 7.6
Hz, 2H, CH2), 3.29-3.69 (AA′BB′, 4H, CH2); 13C NMR δ 15.82,
24.71, 29.94, 31.11, 124.33, 131.82, 214.93; IR (neat) 1053 cm-1
(CdS); MS m/z 428 (M+). Anal. Calcd for C7H9BrS3Se2: C,
19.68; H, 2.12. Found: C, 19.64; H, 2.16.
Attem p ted Cycliza tion Rea ction s of 21: Rea ction A. A
mixture of 21 (58 mg, 0.13 mmol) and sodium iodide (40 mg,
0.27 mmol) in DMF (1.1 mL) was stirred at 80 °C for 5 h. Water
(30 mL) was then added, and the resulting mixture was
extracted with carbon disulfide (30 mL × 3). The extract was
washed with water (50 mL × 2) and brine (50 mL × 2), dried
(MgSO4), and concentrated in vacuo. Silica gel column chro-
matography of the residue eluted with carbon disulfide gave
4,4′-bis(5-ethylseleno-2-thioxo-1,3-dithiolo)-diselenide (20) (Rf
) 0.3, 10 mg, 23% yield) as a pink solid: mp 108 °C; 1H NMR
δ 1.53 (t, J ) 7.6 Hz, 6H, CH3), 2.99 (t, J ) 7.6 Hz, 4H, CH2);
13C NMR δ 15.93, 25.58, 128.25, 130.25, 214.04; IR (neat) 1078
cm-1 (CdS); MS m/z 642 (M+). Anal. Calcd for C10H10S6Se4:
C, 18.81; H, 1.58. Found: C, 18.46; H, 1.67.
Rea ction B. A similar reaction was carried out in refluxing
2-butanone as a solvent. In this case, the main product was
4-ethylseleno-1,3-dithiole-2-thione (22, 92% yield): 1H NMR
δ 1.50 (t, J ) 7.5 Hz, 3H, CH3), 2.92 (t, J ) 7.5 Hz, 2H, CH2),
7.12 (s, 1H, CH); 13C NMR δ 15.79, 24.73, 125.11, 133.01,
215.95; IR (neat) 1059 cm-1 (CdS); MS m/z 242 (M+). Anal.
Calcd for C5H6S3Se: C, 24.89; H, 2.51. Found: C, 24.89; H,
2.54.
Ack n ow led gm en t. The authors are greatly in-
debted to the Grants-in-Aid for Scientific Research from
the Ministry of Education, Culture, Sports, Science and
Technology for financial support.
Su p p or tin g In for m a tion Ava ila ble: Copies of 1H and 13C
NMR spectra for compounds 5 and 6. This material is available
free of charge via the Internet at http://pubs.acs.org.
J O016393H