Synthesis and properties of bis(2,5-dimethylpyrrolo[3,4-d])tetrathiafulvalenes, a class of annelated tetrathiafulvalene derivatives with excellent electron donor properties

Article abstract of DOI:10.1021/jo961282h

The synthesis of the first derivatives of bis(pyrrolo[3,4-d])tetrathiafulvalene has been studied in detail. Starting from the readily available 2,5-dimethylpyrrole (11) and N-phenyl-2,5-dimethylpyrrole, bis(2,5-dimethylpyrrolo[3,4-d])tetrathiafulvalene (8) and the N,N'-disubstituted derivatives 6, 7, 9, and 10 were prepared in good yields by practical procedures. In contrast to the other types of aromatic annelated tetrathiafulvalenes (TTFs), which have appreciably higher oxidation potentials than TTF, the redox behavior of the pyrrolo tetrathiafulvalenes (TTFs) is very close to that of TTF itself. The potential of pyrrolotetrathiafulvalenes as a new series of organic metal building blocks is shown by the two-probe conductivities of the tetracyanoquinodimethane (TCNQ) complexes of the N-phenyl compound 7 and the N-methyl compound 9, which give higher values than TTF-TCNQ under similar conditions.

Full text of DOI:10.1021/jo961282h

J . Org. Chem. 1996, 61, 8117-8124
8117
Syn th esis a n d P r op er ties of
Bis(2,5-d im eth ylp yr r olo[3,4-d ])tetr a th ia fu lva len es, a Cla ss of
An n ela ted Tetr a th ia fu lva len e Der iva tives w ith Excellen t Electr on
Don or P r op er ties
Kyukwan Zong, Wha Chen, Michael P. Cava,* and Robin D. Rogers*
Department of Chemistry, The University of Alabama, Box 870336, Tuscaloosa, Alabama 35487-0336
Received J uly 8, 1996X
The synthesis of the first derivatives of bis(pyrrolo[3,4-d])tetrathiafulvalene has been studied in
detail. Starting from the readily available 2,5-dimethylpyrrole (11) and N-phenyl-2,5-dimethylpyr-
role, bis(2,5-dimethylpyrrolo[3,4-d])tetrathiafulvalene (8) and the N,N′-disubstituted derivatives
6, 7, 9, and 10 were prepared in good yields by practical procedures. In contrast to the other types
of aromatic annelated tetrathiafulvalenes (TTFs), which have appreciably higher oxidation potentials
than TTF, the redox behavior of the pyrrolo tetrathiafulvalenes (TTFs) is very close to that of TTF
itself. The potential of pyrrolotetrathiafulvalenes as a new series of organic metal building blocks
is shown by the two-probe conductivities of the tetracyanoquinodimethane (TCNQ) complexes of
the N-phenyl compound 7 and the N-methyl compound 9, which give higher values than TTF-
TCNQ under similar conditions.
In tr od u ction
We also report some electrochemical results and the
preparation of some new tetracyanoquinodimethane
(TCNQ) complexes having excellent conductivity proper-
ties.
The chemistry of tetrathiafulvalene (TTF, 1) and its
derivatives has been intensively studied for more than
20 years because of the ability of these compounds to form
radical cation salts which have great potential as molec-
ular conductors and even as superconductors.1 In the
latter category, one salt of ET [bis(ethylenedithiolene)-
tetrathiafulvalene, 2], namely (ET)2Cu(SCN)2, supercon-
ducts below Tc ) 10.4 K;2 a number of other TTF-related
salts have also been reported to show superconductivity
under various conditions.1d
Many donor molecules have been synthesized in which
the TTF core is annelated to two benzenoid, thiophene,
or selenophene units (i.e., 3, 4, and 5);3-6 all of these
compounds have oxidation potentials appreciably higher
than that of TTF itself. On the other hand, annelation
of TTF to two electron-rich pyrrole rings should produce
a donor system with a much lower oxidation potential;
this has indeed been verified as we reported very briefly
some time ago in a preliminary communication.7 We now
present a detailed study of the synthesis of the first bis-
(pyrrolo[3,4-d])tetrathiafulvalenes (6-10), including a
greatly improved route to synthesize these compounds.
Resu lts a n d Discu ssion
Syn th esis of P yr r olo-3,4-tr ith ioca r bon a tes. Our
target molecules in this study were pyrrole-annelated
TTF derivatives which would be linear molecules free
from the complication of cis, trans isomers. For this
purpose, precursors were required bearing sulfur func-
tions only in the â-positions. An excellent starting
material proved to be the readily prepared and com-
mercially available 2,5-dimethylpyrrole (11). Reaction
of 11 with freshly generated thiocyanogen in methanol8
smoothly (82%) afforded the known 2,5-dimethyl-3,4-
dithiocyanopyrrole (12),9 which reacted with BOC anhy-
dride to give (90%) the corresponding N-BOC derivative
13, as shown in Scheme 1.
X Abstract published in Advance ACS Abstracts, October 15, 1996.
(1) For a recent review: (a) In Synthetic Metals, Proceedings of the
International Conference on Synthetic Metals ICSM 1986; Shirakawa,
H., Yamabe, T., Eds.; Kyoto, J apan, 1987; Vol 17-19. (b) Schukat, G.;
Richter, A. M.; Fanghanel, E. Sulfur Reports 1987, 7, 177. (c) Garin,
J . Adv. Heterocycl. Chem. 1995, 62, 249. (d) Williams, J . M.; Ferraro,
J . R.; Thorn, R. J .; Carlson, D. D.; Geiser, U.; Wang, H. H.; Kini, A.
M.; Whangboo, M.-H. Organic Superconductors (Including Fullerenes);
Synthesis, Structure, Properties, and Theory; Grimes, R. N., Ed.;
Prentice Hall: Englewood Cliffs, NJ , 1992.
(2) Urama, H.; Yamochi, H.; Saito, G.; Nozawa, K.; Sugano, T.;
Kinoshita, M.; Sato, S.; Oshima, K.; Kawamoto, A.; Tanaka, J . Chem.
Lett. 1988, 55.
(3) Lerstrup, K.; Talham, D.; Bloch, A.; Cowan, D. J . Chem. Soc.,
Chem. Commun. 1982, 336.
(4) Shu, P.; Chiang, L.; Emge, T.; Holt, D.; Kistenmacher, T.; Lee,
M.; Stokes, J .; Poehler, T.; Cowan, D. J . Chem. Soc., Chem. Commun.
1981, 920.
(5) Cowan, D. O.; Chiang, L.-Y.; Shu, P.; Holt, D. J . Org. Chem. 1983,
48, 473.
(6) Ketchwan, R.; Hornfeldt, A.-B.; Gronowitz, S. J . Org. Chem.
1984, 49, 1117.
Several methods were explored to convert 13 into the
corresponding trithiocarbonate 15. In the first of these,
we employed the Ueno procedure for the conversion of a
(7) Chen, W.; Cava, M. P.; Takassi, M. A.; Metzger, R. M. J . Am.
Chem. Soc. 1988, 110, 7903.
(8) Matteson, D. S.; Snyder, H. R. J . Am. Chem. Soc. 1957, 79, 3610.
(9) Soderback, K.; Gronowitz, S. Acta. Chem. Scand. 1961, 15, 227.
S0022-3263(96)01282-0 CCC: $12.00 © 1996 American Chemical Society

8118 J . Org. Chem., Vol. 61, No. 23, 1996
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t for 18a
colorless/plate
Zong et al.
color/shape
empirical formula
formula weight
C22H30N2O4S4
514.72
temperature
173(2) K
crystal system
triclinic
space group
P1h
unit cell dimensions
(1826 reflections
in full ø range)
volume
Z
density (calculated)
absorption coefficient
diffractometer/scan
radiation/wavelength
F (000)
a ) 6.8845(8) Å
b ) 9.0553(10) Å
c ) 10.9633(12) Å
637.10(12) Å3
1
R ) 89.012(2)°
â ) 78.752(2)°
γ ) 72.068(2)°
1.342 mg/m3
0.403 mm-1
Siemens SMART/CCD area detector
Mo KR (graphite monochrom.)/0.710 73 Å
272
crystal size
ø range for data collection
index ranges
reflections collected
independent/observed refls.
refinement method
computing
0.35 × 0.35 × 0.05 mm
1.90 to 23.30°
-5 e h e 7, -5 e k e10, -11 e l e 12
2548
1779 (Rint ) 0.0835)/1654 ([I > 2σ(I)])
Full-matrix least-squares on F2
SHELXTL, Ver. 5
data/restraints/parameters
goodness-of-fit on F2
SHELX-93 weight parameters
final R indices [I > 2σ(I)]
R indices (all data)
largest diff peak and hole
1769/0/150
1.300
0.0000, 2.7945
R1 ) 0.0757, wR2 ) 0.1587
R1 ) 0.0931, wR2 ) 0.1707
0.339 and -0.452 eÅ-3
a
The authors have deposited atomic coordinates for 18 with the Cambridge Crystallographic Data Centre. The coordinates can be
obtained, on request, from the Director, Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge, CB2 1EZ, U.K.
Sch em e 1
F igu r e 1. Compound18.
gene in the presence of triethylamine to give 15 (60%
overall).11 It is noteworthy that the N-BOC group of 13
survived the conditions of the LAH reduction.
Attempts to reduce 13 to dithiol 16 using NaBH4 led
to an unexpected result. Instead of 16, a virtually
quantitative yield of a sparingly soluble yellow product
was obtained which proved to be the eight-membered ring
18 (Scheme 2). The same compound was formed in high
yield when dithiocyanate 13 was reacted with sodium
methoxide or with hydrazine.12 The conversion of a
thiocyanate to a disulfide by an appropriate nucleophile
is well documented;13 however, the use of NaBH4 in such
a reaction is, to our knowledge, unprecedented.
When the reaction mixture was heated to 180 °C, 18
cleanly underwent facile loss of its BOC protecting
groups14 to give the unsubstituted 22. The latter reacted
with sodium hydride in DMF to give a dianion which
reacted with iodomethane or 1-iodopentane to give the
corresponding dialkylated 23 and 24 in high yields.
thiocyanate to a thioester.10 Thus, the radical-initiated
Although 18 was resistant to reduction by NaBH4, it
reaction of 13 with tributyltin hydride afforded, after
careful chromatography, the oily bis(tributylstannyl)
compound 14, which reacted with thiophosgene to give
the desired crystalline trithiocarbonate 15 (48% overall).
A simpler route to 15 involved the direct lithium alumi-
num hydride (LAH) reduction of dithiocyanate 13 to give
the air-sensitive dithiol 16, which reacted with thiophos-
underwent reductive cleavage by LAH to form dithiol 16,
(11) (a) The Chemistry of the Thiol Group; Patai, S., Ed.; Chemistry
of Functional Groups 31; J ohn Wiley & Sons: London, 1974. (b)
Schoberl, A.; Wagner, A. Methoden Der Organischen Chemie; Georg
Thieme Verlag: Stuttgart, 1955; Chapter IX, p 23. (c) Ookawa, A.;
Yokoyama, S.; Soai, K. Synth. Commun. 1986, 22, 1500.
(12) Maiti, S. N.; Spevak, P.; Singh, M. P.; Reddy, N. Synth.
Commun. 1988, 18, 575.
(13) Tarbell, D. S.; Harnish, D. P. Chem. Rev. 1951, 49, 79.
(14) Rawal, V. H.; Cava, M. P. Tetrahedron Lett. 1985, 26, 6141.
(10) Ueno, Y.; Nozomi, M.; Okawara, M. Chem. Lett. 1982, 1119.

Synthesis and Properties of Tetrathiafulvalenes
J . Org. Chem., Vol. 61, No. 23, 1996 8119
Sch em e 2
Sch em e 3
Sch em e 4
which was directly reacted with thiophosgene to give
trithiocarbonate 15 in 93% yield. The route to 15 via 18
thus proved to be the best one for the preparation of
multigram amounts of 15.
The N-phenyl analog (21) of 15 was conveniently
prepared by a similar procedure. Thus, 2,5-dimethyl-N-
phenylpyrrole15 was converted to 21 by way of its 3,4-
dithiocyano derivative 17 and 19.
The structure of 18 was confirmed by X-ray crystal-
lography, as shown in Figure 1. The two dithiopyrrole
units lie in parallel planes and in a transoid configura-
tion, an arrangement which minimizes the lone pair
repulsions of the four sulfur atoms. The crystal data and
structure refinement for 18 are given in Table 1.
Syn th esisofBis(p yr r olo[3,4-d ])tetr a th ia fu lva len es.
A number of procedures were explored with the objective
of converting either trithiocarbonate 15 or dithiol 16 into
the corresponding TTF 6. In the first of these, the well-
known coupling reaction of a thione by a trivalent
phosphorus reagent was attempted.1b When thione 15
was heated overnight with triethyl phosphite, however,
TTF 6 was not obtained but the phosphonate ester 25
was isolated in 45-55% yield as shown in Scheme 3.
Formation of this type of product, initiated by a carbo-
philic rather than a thiophilic attack of phosphorus at
the thione function, has been described in other cases.16
We also envisioned the possibility of forming 6 by the
basic-induced coupling of the appropriate dithiolium salt
precursor.17,18 Thus, dithiol 16 was reacted with triethy-
lamine followed by dibromomethane to give (70%) the
crystalline 1,3-dithiole 26 (Scheme 4). Reaction of 26
with triphenylcarbenium fluoroborate gave a dark green
solution, presumably containing salt 27, which was
treated with triethylamine. No coupling product 6 was
produced. In a variation of this approach, thione 15 was
reacted sequentially with trimethyloxonium fluoroborate,
NaBH4, HBF4, and triethylamine;19 the TTF derivative
6 was not obtained.
The reaction of tetrachloroethylene with the dianion
of o-benzenedithiol to give dibenzotetrathiafulvalene has
been known since 1926.20 More recently, analogous
reactions have been used to prepare related systems,
(17) (a) Klingsberg, E. J . Am. Chem. Soc. 1962, 84, 3410. (b) Ibid.
1964, 86, 5290.
(18) Coffen, D. L.; Chambers, J . Q.; Williams, D. R.; Garrett, P. E.;
Canfield, N. D. J . Am. Chem. Soc. 1971, 93, 2258.
(19) (a) Rondestvedt, C. Org. React. 1976, 24, 225. (b) Ibid. 1960,
11, 198.
(15) Al-awar, R.; Wahl, G. H., J r. J . Chem. Educ. 1990, 67, 265.
(16) Parg, P. R.; Kilburn, J . D.; Ryan, T. G. Synthesis 1994, 195.
(20) Hurtly, W. R. H.; Smiles, S. J . Chem. Soc. 1926, 2263.

8120 J . Org. Chem., Vol. 61, No. 23, 1996
Zong et al.
Sch em e 5
Sch em e 7
Ta ble 2. Cyclic Volta m m etr y of Com p ou n d s 6, 7, 8, 9,
a n d 10 vs SCEa
1
2
compound
E1/2
E1/2
6
7
8
9
0.613
0.289
0.298
0.289
0.275
0.390
0.510
1.081
0.838
0.863
0.833
0.805
0.765
0.921
10
1 (TTF)
2 (ET)
a
Cyclic voltammetry was carried out in a 0.1 M solution of
Bu4NPF6 in dichloromethane at rt; scan speed 100 mV/s.
Sch em e 6
including tetratellurafulvalenes.21,22 In the case of our
dithiol 16, the crystalline dichlorofulvene intermediate
29 was formed in 60% yield as shown in Scheme 5.
However, attempts to react 29 with a further molecule
of 16 were unsuccessful.
Ta ble 3. Room Tem p er a tu r e 2-P r obe Con d u ctivities of
TCNQ Com p lexes of 1, 7, 8, a n d 9
donors
acceptor
ratio
conductivitiesa σ, S cm-1
Our first successful synthesis of 6 employed the Ueno
methodology, in which a thione is coupled photochemi-
cally using hexabutyldistannane as the desulfurizing
agent.23 Unfortunately, yields were variable and low,
averaging only 10-12%. A similar reaction using the
N-phenyl thione 21 gave the corresponding TTF 7 in 15%
yield, as shown in Scheme 6.
The phosphite coupling of dithiocarbonates to TTF
derivatives often is more successful than trithiocarbonate
couplings. Thiones 15, 21, and 30 were all converted in
high yields (90-92%) by mercuric acetate into the dithio-
carbonates 31, 32, and 33 (Scheme 7).24
When the dithiocarbonates were heated with triethyl
phosphite at 110 °C for 12 h, the corresponding TTF
derivatives 6, 7, and 9 were formed in good yields (73, 53,
and 55%, respectively), and the pure products were easily
recovered directly from the reaction mixtures. The
N-BOC 31 was also an excellent precursor to its N-alkyl
analogs. When the reaction mixture was heated to 180-
1
7
8
9
TCNQ
TCNQ
TCNQ
TCNQ
1:1
1:1
1:1
1:1
0.89
0.58
1.2 × 10-7
1.50
a
The values represent the averages of five measurements of
each complex.
190 °C, 31 gave the unprotected 34 (92%), which could
be alkylated under standard conditions (NaH, DMF) to
give the N-methyl and N-pentyl compounds (33 and 35)
in almost quantitative yields.
Removal of the N-BOC protecting groups of 6 was best
carried out by treatment of 6 with sodium methoxide.
The resulting TTF, 8, could be cleanly dialkylated to give
the N,N′-dialkyl derivatives 9 and 10, as shown in
Scheme 8.
Bis(p yr r olo[3,4-d ])tetr a th ia fu lva len es a s Electr on
Don or s. Compounds 7, 8, 9, and 10 proved to be
excellent donors and showed two quasi-reversible oxida-
tion waves, while the oxidation potentials for 6 were
relatively higher due to the electron-withdrawing BOC
groups (Table 2). For comparison with the well-known
donors TTF (1) and ET (2), the oxidation potentials for
these compounds were determined under the same
conditions and in the same equipment.
(21) Bajwa, G. S.; Berlin, K. D.; Pohl, H. A. J . Org. Chem. 1976, 41,
145.
(22) Mizuno, M.; Cava, M. P. J . Org. Chem. 1978, 43, 416.
(23) Ueno, Y.; Nakayama, A.; Okawara, M. J . Am. Chem. Soc. 1976,
98, 7440.
(24) Svenstrup, N.; Rasmussen, K. M.; Hansen, T. K.; Becher, J .
Sythesis 1994, 809.

Synthesis and Properties of Tetrathiafulvalenes
J . Org. Chem., Vol. 61, No. 23, 1996 8121
(260 g) and NaCl (40 g). After the ice melted, the resulting
precipitate was collected by filtration, washed with water, and
air-dried. The crude material was purified by recrystallization
in dichloromethane/hexane (1:4) to give the pure product (90.1
g, 82%) as a white solid: mp 134-136 °C (lit.8,9 mp 132 °C);
1H NMR (360 MHz, CDCl3) δ 9.00 (s, 1H), 2.39 (s, 6H).
2,5-Dim e t h yl-3,4-d it h iocya n o-N -t er t-b u t oxyca r b on -
ylp yr r ole (13). To a solution of 2,5-dimethyl-3,4-dithiocyan-
opyrrole (12) (6.00 g, 28.70 mmol) in acetonitrile (30 mL) were
added di-tert-butyl dicarbonate (6.27 g, 28.7 mmol), a catalytic
amount of DMAP (50 mg), and triethylamine (4.0 mL, 28.7
mmol) at rt. The reaction mixture was heated to 45 °C and
stirred for 45 min. The reaction was cooled to rt and the
solvent was removed under reduced pressure. The residue was
purified by recrystallization in CH2Cl2/hexane (1:4) to afford
the product (8.00 g, 90%) as pale yellow crystals: mp 165-
167 °C; 1H NMR (360 MHz, CDCl3) δ 2.60 (s, 6H), 1.64 (s, 9H);
13C NMR (90 MHz, CDCl3) δ 148.06, 138.97, 109.86, 104.85,
87.05, 27.86, 14.61; MS (m/e, M+) 309 (15), 209 (100), 151 (31),
93 (21). Anal. Calcd for C13H15N3S2O2: C, 50.48; H, 4.85; N,
13.59; S, 20.71. Found: C, 49.95; H, 4.62; N, 13.51; S, 20.96.
2,7-Bis(ter t-bu toxycar bon yl)-1,3,6,8-tetr am eth yl-[1,2,5,6]-
tetr a th iocin o[4,5-c]p yr r ole (18). To a solution of dithiocy-
anate 13 (14.78 g, 47.85 mmol) in aqueous THF (180 mL, 20:1
THF/H2O) was added NaBH4 (1.99 g, 52.63 mmol) at rt. While
the mixture was stirred for 2.25 h the reaction became
exothermic (H2 evolution) and a considerable amount of
precipitate was formed. The reaction mixture was diluted with
water (100 mL), and the solid was collected by filtration and
washed with water (20 mL). The air-dried product was
purified by treatment with hot acetone to afford the product
(12.3 g, 100%) as a pale yellow powder. Recrystallization from
CHCl3/hexane (1:2) gave pale yellow crystals: mp > 250 °C;
1H NMR (360 MHz, CDCl3) δ 2.56 (s, 6H), 1.59 (s, 9H); 13C
NMR (90 MHz, CDCl3) δ 218.60, 149.25, 137.01, 120.42, 85.09,
46.78, 27.96, 14.65; MS (m/e) 314 (M+, 68), 250 (100), 156 (47),
125 (39), 100 (57), 81 (90); IR (KBr) 3400 (s), 1510 (m), 1395
(m), 640 (m) cm-1. Anal. Calcd for C22H30N2O4S4: C, 51.36;
H, 5.83; N, 5.44; S, 24.90. Found: C, 51.52; H, 5.96; N, 5.41;
S, 24.56.
5-ter t-Bu toxyca r bon yl-4,6-d im eth yl-2-th ioxo-1,3-d ith i-
olo[4,5-c]p yr r ole (15). Meth od 1. To a solution of 13 (5.00
g, 16.2 mmol) in benzene (45 mL) were added 2.0 equiv of
tributyltin hydride (9.30 g, 32.3 mmol) and a catalytic amount
of 2,2′-azobis(isobutyronitrile) (AIBN) under nitrogen at rt. The
stirred reaction mixture was heated to 75 °C for 5 h and then
cooled to rt. After removal of the solvent, the crude product
was purified by chromatography (silica gel) using ethyl acetate/
hexane (1:10) as the eluent to afford 2,5-dimethyl-3,4-bis-
(tributylthiostannyl)-N-tert-butoxycarbonylpyrrole (14, 8.10 g)
as a pale yellow, light-sensitive oil: 1H NMR (CDCl3) δ 2.31
(s, 6H), 1.63-0.89 (m, 63H). To a solution of the stannyl
compound (8.10 g) in benzene (60 mL) was added dropwise a
solution of thiophosgene (1.10 g, 9.6 mmol) in benzene (40 mL)
under nitrogen at rt. After the mixture was stirred for 2 h,
the reaction mixture was poured into water (200 mL). The
organic layer was separated, dried over Na2SO4, and concd
under reduced pressure. The resulting precipitate was filtered,
washed with diethyl ether, and recrystallized from CH2Cl2/
hexane (1:3) to give 15 (2.5 g, 48% overall) as yellow needles.
Meth od 2. To a solution of lithium aluminum hydride (1.20
g, 32.4 mmol) in dry THF (25 mL) was slowly added 2,5-
dimethyl-3,4-dithiocyano-N-tert-butoxycarbonylpyrrole (13) (5.10
g, 16.1 mmol) in dry THF (50 mL) under nitrogen. The
reaction mixture was stirred for 5 h at rt, and then acetic acid
in diethyl ether was slowly added until the color of the solution
changed from pink to yellow. The reaction mixture was added
to ice water (200 mL), extracted with diethyl ether (100 mL ×
2), and washed with brine (50 mL). The organic layer was
dried over sodium sulfate and concd to afford dithiol 16 (2.90
g, 70%) as orange crystals: 1H NMR (360 MHz, CDCl3) δ 2.64
(s, 2H), 2.45 (s, 6H), 1.59 (s, 9H); MS (m/e) 259 (M+, 15), 159
(100), 126 (51), 94 (14). Into neat dithiol 16 (1.05 g, 3.89 mmol)
was added triethylamine (1.2 mL, 8.56 mmol) under nitrogen
at rt. Benzene (15 mL) was then added, and the reaction
mixture was stirred for 10 min. A solution of thiophosgene
Sch em e 8
Compounds 7, 8, 9, and 10 all showed lower first half-
wave oxidation potentials than TTF (0.390 V) and ET
(0.510 V). It may be noted that the pyrrolotetrathiaful-
valene (10) with long N-alkyl chains showed the lowest
oxidation potential, presumably due to the electron
donating effect of the long alkyl groups.
With donors 7, 8, and 9 in hand, complex formation
with TCNQ was investigated. As expected, all three
formed crystalline charge-transfer complexes in acetoni-
trile, which were shown to be 1:1 complexes by elemental
analysis. Two-probe conductivity measurements on com-
pressed powders25 and those compared to TTF-TCNQ
as a standard were determined in the same equipment.
The results are shown in Table 3. In comparison with
TTF-TCNQ (entry 1), the N-phenyl derived annelated
TTF-TCNQ complex showed comparable conductivity
(entry 2, 0.58) as a conductor. However, the pyrrolo-
annelated TTF-TCNQ complex (entry 3) showed poor
conductivity (around 1.2 × 10-7) in the semiconductor
range. Most strikingly, the N-methyl derived annelated
TTF-TCNQ complex showed excellent conductivity (en-
try 4, 1.50), even higher than that of TTF-TCNQ.
Con clu sion s
Practical syntheses have been developed for several
bis(pyrrolo[d])tetrathiafulvalenes. The N-unsubstituted
(8), N-phenyl (7), and N-alkyl (9 and 10) derivatives all
show excellent donor properties, and 7 and 9 form 1:1
TCNQ complexes, which are good conductors. Further
work that is in progress in our laboratory is aimed at
additional studies of this new annelated TTF family,
including the synthesis of unsymmetrical analogs and the
growth of single-crystal conducting salts.
Exp er im en ta l Section
Gen er a l. All of the reagents were obtained from com-
mercial suppliers and used without further purification unless
otherwise indicated. THF was distilled from sodium ben-
zophenone ketyl. Conductivities were measured using an
instrument made in our laboratory according to ref 25.
2,5-Dim eth yl-3,4-d ith iocya n op yr r ole (12). To a solution
of potassium thiocyanate (204 g, 2.05 mol) in MeOH (250 mL)
at -78 °C was added slowly a precooled solution of Br2 (160 g,
1.00 mol) in MeOH (250 mL). The reaction mixture was
stirred at -40 °C for 45 min, followed by the addition of a
precooled solution of 2,5-dimethylpyrrole (50.0 g, 0.526 mol)
in MeOH (175 mL). The reaction mixture was stirred at -25
°C for 45 min, and then it was poured into a mixture of ice
(25) Wudl, F.; Bryce, M. R. J . Chem. Educ. 1990, 67, 717.

8122 J . Org. Chem., Vol. 61, No. 23, 1996
Zong et al.
(492 mg, 4.28 mmol) in benzene (20 mL) was then introduced
dropwise, and the reaction mixture was stirred for a further
30 min, then concd under reduced pressure, diluted with water
(30 mL), and extracted with CH2Cl2 (20 mL × 3). The
combined extracts were dried over sodium sulfate and concd
under reduced pressure to afford the crude product, which was
passed through a short column of silica gel. Purification by
recrystallization in dichloromethane/hexane (1:5) gave 15 (1.00
g, 85.4%, 60% overall) as yellow needles: mp 165-167 °C; 1H
NMR (360 MHz, CDCl3) δ 2.39 (s, 6H), 1.62 (s, 9H); 13C NMR
(90 MHz, CDCl3) δ 218.60, 149.45, 124.06, 120.53, 85.15, 28.05,
16.24; MS (m/e) 301 (M+, 32), 303 (6), 245 (31), 201 (13), 57
(100); IR (KBr) 1720 (s), 1600 (m), 1350 (m), 1300 (m), 1150
(two molecular DMFs): C, 46.95; H, 6.08; N, 12.17; S, 27.82.
Found: C, 46.98; H, 6.06; N, 12.12; S, 27.94.
Gen er a l P r oced u r e for N-Alk yla tion . 1,2,3,6,7,8-Hex-
a m eth yl-[1,2,5,6]tetr a th iocin o[3,4-c:8,7-c′]d ip yr r ole (23).
To a solution of 22 (2.13 g, 6.78 mmol) in dry DMF (30 mL)
was added hexane-washed NaH (650 mg, 27.12 mmol) in
portions under nitrogen at rt. The mixture was stirred for 5
min, followed by the addition of iodomethane (568 mg, 23.66
mmol). The solution was stirred for 20 min and water (20 mL)
was added carefully. The precipitate was washed with metha-
nol (10 mL) and then acetonitrile (20 mL) to give the product
(2.2 g, 95%) as a white solid: mp > 250 °C; 1H NMR (360 MHz,
CDCl3) δ 3.40 (s, 6H), 2.34 (s, 12H); 13C NMR (90 MHz, CDCl3)
δ 116.70, 116.07, 31.35, 11.55; IR (CDCl3) 3040 (s), 1550 (m),
1260 (s) cm-1. Anal. Calcd for C14H18N2S4: C, 49.12; H, 5.26;
N, 8.18; S, 37.42. Found: C, 49.03; H, 5.24; N, 8.70; S, 36.97.
2,7-Dicyclopen tyl-1,3,6,8-tetr am eth yl-[1,2,5,6]tetr ath io-
cin o[3,4-c:8,7-c′]d ip yr r ole (24). Alkylation using 1-iodopen-
tane gave (92%) pale yellow crystals: mp 229-232 °C; 1H NMR
(360 MHz, CDCl3) δ 3.72 (t, J ) 7.86 Hz, 4H), 2.36 (s, 12H),
1.62 (m, 4H), 1.34 (m, 8H), 0.92 (t, J ) 6.73 Hz, 6H); 13C NMR
(90 MHz, CDCl3) δ 134.34, 116.21, 45.27, 30.11, 28.98, 22.27,
13.86, 11.03; IR (CDCl3) 3040 (s), 1560 (s), 1450 (m), 1395 (m),
1260 (s) cm-1. Anal. Calcd for C22H34N2S4: C, 58.14; H, 7.48;
N, 6.16; S, 28.19. Found: C, 57.61; H, 7.58; N, 6.13; S, 28.01.
5-ter t-Bu toxycar bon yl-4,6-dim eth yl-2(O,O-dieth ylph os-
p h on yl)-1,3-d ith iolo[4,5-c]p yr r ole (25). To 15 (2.10 g, 6.6
mmol) was added triethyl phosphite (8 mL) in one portion
under nitrogen at rt. The reaction mixture was heated at 110
°C for 5 h. Excess triethyl phosphite was removed under
vacuum (1 mmHg) at 80 °C, and the residue was purified by
silica chromatography (100 g) using ethyl acetate/hexane (2:
1) to afford the product (1.20 g, 45%) as a pale yellow oil: 1H
NMR (360 MHz, CDCl3) δ 5.08 (d, J ) 6.6 Hz, 1H), 4.32 (m,
4H), 2.30 (s, 6H), 1.56 (s, 9H), 1.29 (t, J ) 7.5 Hz, 6H); 13C
NMR (90 MHz, CDCl3) δ 149.19, 123.09, 122.04, 83.58, 64.17,
64.09, 53.44, 51.69, 28.07, 16.48, 16.37, 16.31; MS (m/e) 407
(M+, 69), 351 (17), 307 (37), 169 (100), 57 (84); IR (neat) 3000
(m) cm-1
. Anal. Calcd for C12H15NO2S3: C, 47.82; H, 5.06;
N, 4.62; S, 31.84. Found: C, 47.82; H, 5.02; N, 4.65; S, 31.91.
Meth od 3. To a solution of 18 (7.35 g, 14.30 mmol) in dry
THF (250 mL) was added LiAlH4 (1.19 g, 31.46 mmol) in
portions under nitrogen at rt. The reaction mixture was
stirred for 3 h, and a slight excess of acetic acid in diethyl ether
was then added carefully. The reaction mixture was concd
under reduced pressure, followed by the addition of water (20
mL) and diethyl ether (150 mL). The mixture was shaken
vigorously and allowed to stand for 10-15 min. The clear
ether layer was carefully decanted, and this procedure was
repeated three times. The combined ether layers were dried
over Na2SO4 and concd under reduced pressure. The crude
product, dithiol, 16 was dried under high vacuum (0.5 mmHg)
for 5 h, then dissolved in degassed benzene (50 mL) and
triethylamine (5.89 mL, 42.22 mmol) that were added with
vigorous stirring under nitrogen at rt. To the solution was
added dropwise thiophosgene (3.29 g, 28.60 mmol) in benzene
(150 mL) under nitrogen. The reaction mixture was stirred
for 1 h, the benzene was removed under reduced pressure,
water (180 mL) was added, and the mixture was extracted with
CH2Cl2 (150 mL × 3). The combined extract was dried over
Na2SO4, concd, and purified by short column chromatography
(silica gel) using dichloromethane/hexane (3:1) as the eluent
to afford 15 (8.05 g, 93%) as yellow needles.
(s), 1760 (s), 1350 (m), 1310 (s), 1270 (s), 980 (m), 870 (m) cm-1
.
2,5-Dim et h yl-3,4-d it h iocya n o-N-p h en ylp yr r ole (17).
This compound was prepared from 2,5-dimethyl-N-phenylpyr-
role15 by the procedure used for the preparation of 12; 75%
yield, pale yellow crystals: mp 112-114 °C; 1H NMR (360
MHz, CDCl3) δ 7.65-7.43 (m, 2H), 7.26-7.12 (m, 3H), 2.16 (s,
6H); 13C NMR (90 MHz, CDCl3) δ 137.64, 136.57, 129.95,
129.70, 127.47, 110.67, 100.37, 11.77; IR (CDCl3) 3040 (m),
Anal. Calcd for C16H26NO5S2P: C, 47.17; H, 6.38; N, 3.43; S,
15.72; P, 7.61. Found: C, 47.43; H, 6.33; N, 3.01; S, 15.65; P,
7.90.
Dista n n a n e Cou p lin g Rea ction s. (a ) Bis(2,5-d im eth yl-
N -t er t -b u t o x y c a r b o n y lp y r r o lo [3,4-d ])t e t r a t h i a fu l-
va len e (6). To a solution of 15 (0.50 g, 1.60 mmol) in benzene
(500 mL) was added hexabutyldistannane (1.40 g, 2.4 mmol).
The reaction mixture was irradiated with a 250-W medium
pressure mercury immersion lamp for 5 h under nitrogen.
After the solvent was removed under reduced pressure, the
residue was treated with hexane to give a pale yellow solid.
Purification by silica chromatography using ethyl acetate/
hexane (1:10) as the eluent, followed by recrystallization from
acetonitrile, gave 6 (44.0 mg, 10%) as pale yellow crystals: mp
> 250 °C; 1H NMR (360 MHz, CDCl3) δ 2.32 (s, 12H), 1.58 (s,
18H); 13C NMR (90 MHz, CDCl3) δ 149.42, 121.36, 120.70,
119.81, 83.91, 28.12, 16.31; MS (m/e) 538 (M+, 14), 438 (39),
426 (93), 382 (76), 338 (100), 57 (41); IR (KBr) 2960 (m), 1730
2420 (m), 1610 (m), 1520 (s), 1420 (s), 1250 (s) cm-1
. Anal.
Calcd for C14H11N3S2: C, 58.94; H, 3.85; N, 14.73; S, 22.45.
Found: C, 58.87; H, 3.87; N, 14.65; S, 22.39.
1,3,6,8-Tetr a m eth yl-2,7-bis(p h en yl)-[1,2,5,6]tetr a th io-
cin o[3,4-c:8,7-c′]d ip yr r ole (19). This was prepared from 17
in 100% yield as a pale yellow powder: mp > 250 °C; 1H NMR
(360 MHz, CDCl3) δ 7.61-7.29 (m, 8H), 7.15-7.09 (m, 2H),
2.14 (s, 12H); 13C NMR (90 MHz, CDCl3) δ 138.09, 135.69,
129.45, 128.62, 127.95, 116, 65, 11.91; IR (CDCl3) 3400 (s),
3000 (s), 1550 (s), 1520 (s), 1420 cm-1
. Anal. Calcd for
C24H22N2S4: C, 61.74; H, 4.72; N, 6.00; S, 27.46. Found: C,
61.57; H, 4.70; N, 5.95; S, 26.95.
(s), 1310 (s), 1280 (m), 1170 (m), 1130 (s) cm-1
.
4,6-Dim eth yl-5-p h en yl-2-th ioxo-1,3-d ith iolo[4,5-c]p yr -
r ole (21). This was prepared from 19 by the LAH reduction
procedure as yellow crystals in 80% yield: mp 138-140 °C;
1H NMR (360 MHz, CDCl3) δ 7.66-7.42 (m, 2H), 7.26-7.12
(m, 3H), 2.04 (s, 6H); 13C NMR (90 MHz, CDCl3) δ 198.45,
136.95, 129.40, 128.15, 127.45, 121.89, 108.95, 12.72; IR (KBr)
1720 (s), 1600 (m), 1350 (m), 1300 (m), 1150 (m) cm-1. Anal.
Calcd for C13H11NS3: C, 56.28; H, 3.97; N, 5.05; S, 34.67.
Found: C, 56.23; H, 4.00; N, 4.99; S, 34.60
1,3,6,8-Tetr a m eth yl-2H,7H-[1,2,5,6]tetr a th iocin o[3,4-c:
8,7-c′]p yr r ole (22). 18 (1.00 g, 1.94 mmol) was placed in a
25 mL round-bottom flask and heated to 190-195 °C under
nitrogen for 30-40 min. The material was cooled to room
temperature and recrystallized from DMF to afford 22 (608
mg, 99%) as pale yellow needles: mp > 250 °C; 1H NMR (360
MHz, CDCl3) δ 7.95 (s, 2H), 2.26 (s, 12H); 13C NMR (90 MHz,
CDCl3) δ 118.67, 109.23, 12.73; IR (CDCl3) 3400 (m), 3040 (s),
1680 (s), 1380 (m), 1260 (s) cm-1. Anal. Calcd for C18H28N4O2S4
(b) Bis(2,5-d im eth yl-N-p h en ylp yr r olo[3,4-d ])tetr a th i-
a fu lva len e (7). Obtained from 21 in 15% yield, yellow
1
crystals: mp > 250 °C; H NMR (360 MHz, CDCl3) δ 7.52-
7.38 (m, 6H), 7.22-7.15 (m, 4H), 1.97 (s, 12H); 13C NMR (90
MHz, CDCl3) δ 138.27, 129.26, 128.25, 128.09, 120.37, 119.48,
116.15, 12.49; IR (KBr) 3215 (s), 3050 (m), 1645 (m), 1450 (m),
1105 (m), 970 (m), 860 (m) cm-1; MS (m/e) 490 (M+, 100), 289
(4), 261 (39), 246 (76), 233 (66), 200 (39). Anal. Calcd for
C26H22N2S4: C, 63.64; H, 4.52; N, 5.71; S, 26.13. Found: C,
63.50; H, 4.31; N, 5.45; S, 26.45.
5-ter t-Bu toxyca r bon yl-4,6-d im eth yl-1,3-d ith iolo[4,5-c]-
p yr r ole (26). Into neat dithiol 16 (4.10 g, 15.4 mmol) was
added triethylamine (3.40 g, 33.0 mmol) under nitrogen at rt.
To the deep red solution was added excess methylene bromide
(ca. 10 mL) in one portion. After 10 min, 30 mL of methylene
chloride was added, and the resulting mixture was refluxed
at 35 °C for 5 h under nitrogen. The white precipitate was
filtered off, and the filtrate was washed twice with water (100

Synthesis and Properties of Tetrathiafulvalenes
J . Org. Chem., Vol. 61, No. 23, 1996 8123
mL). The organic layer was dried over Na2SO4 and concd
under reduced pressure. Purification by chromatography on
silica gel using ethyl acetate/hexane (1:8) as the eluent,
followed by recrystallization from CH2Cl2-hexane (1:5), af-
4,6-Dim eth yl-2-oxo-5H-1,3-d ith iolo[4,5-c]p yr r ole (34).
This was prepared by pyrolysis of the BOC derivative 31 (see
synthesis of 22 from 18 for conditions). It formed white
1
crystals (92%): mp 183-184 °C; H NMR (360 MHz, CDCl3)
1
forded 26 as white crystals (2.0 g, 60%): mp 110-112 °C; H
δ 7.93 (s, 1H), 2.28 (s, 6H); 13C NMR (90 MHz, CDCl3) δ 196.55,
118.66, 109.30, 12.75; IR (CDCl3) 3400 (s), 2995 (m), 1780 (s),
1540 (m) cm-1. Anal. Calcd for C7H7NS2O: C, 45.40; H, 3.78;
N, 7.56; S, 34.59. Found: C, 45.48; H, 3.86; N, 7.55; S, 34.61.
NMR (200 MHz, CDCl3) δ 4.75 (s, 2H), 2.32 (s, 6H), 1.56 (s,
9H); MS (m/e) 271 (M+, 80), 216 (35), 171 (47), 170 (100), 138
(30), 57 (50); IR (KBr) 3000 (m), 2930 (m), 1740 (s), 1350 (s),
1310 (s), 1150 (s), 870 (s), 780 (m) cm-1
C
.
Anal. Calcd for
12H17NS2O2: C, 53.13; H, 6.27; N, 5.16; S, 23.61. Found: C,
53.17; H, 6.31; N, 5.14; S, 23.70.
Alk yla t ion of 34. 4,6-Dim et h yl-5-p en t yl-2-oxo-1,3-
d ith iolo[4,5-c]p yr r ole (35). For the procedure used, see
general N-alkylation (preparation of 24). Purification by
chromatography (silica gel) and using CH2Cl2/hexane (3:1) as
the eluent afforded a colorless oil (94%): 1H NMR (360 MHz,
CDCl3) δ 3.80 (t, J ) 7.6 Hz, 2H), 2.25 (s, 6H), 1.65 (m, 2H),
1.32 (m, 4H), 0.92 (t, J ) 6.8 Hz, 3H); 13C NMR (90 MHz,
CDCl3) δ 196.20, 119.28, 108.20, 44.50, 30.77, 28.88, 22.36,
13.90, 12.31; IR (CDCl3) 2980 (s), 2045 (m), 1760 (s), 1660 (s),
5-ter t-Bu toxyca r bon yl-4,6-d im eth yl-2-d ich lor om eth yl-
en e-1,3-d ith iolo[4,5-c]p yr r ole (29). Into neat dithiol 16
(2.90 g, 11.1 mmol) were added tetrachloroethylene (ca. 15 mL)
and triethylamine (3.20 g, 31.0 mmol). The reaction mixture
was refluxed with stirring under nitrogen for 2 h and then
cooled to rt. Water (200 mL) was added, and the resulting
mixture was extracted with CH2Cl2 (70.0 mL × 3). The
combined organic extract was dried over Na2SO4 and concd
under reduced pressure. Purification by chromatography on
silica gel using ethyl acetate/hexane (1:8) as the eluent,
followed by recrystallization from CH2Cl2/hexane (1:5), af-
1520 (s), 1400 (s), 1250 (m) cm-1
. Anal. Calcd for C12H17-
NOS2: C, 56.47; H, 6.66; N, 5.49; S, 25.09. Found: C, 56.55;
H, 6.71; N, 5.54; S, 25.12.
Gen er a l P r oced u r e for Tr ieth yl P h osp h ite Cou p lin g.
A solution of the dithiocarbonate in triethyl phosphite (1:6 mol
ratio) was heated to 105-110 °C under nitrogen for 12 h. The
product usually separated out during the course of the reac-
tion. The reaction mixture was cooled to rt, double the volume
of methanol was added, and the product was collected by
filtration and washed with methanol. Purification was effected
by washing with hot acetonitrile or recrystallization from DMF
to give the following tetrathiafulvalenes:
(a ) Bis(2,5-d im et h yl-N-ter t-b u t oxyca r b on ylp yr r olo-
[3,4-d ])tetr a th ia fu lva len e (6). 73% yield. The physical and
spectroscopic data were identical to those of the material
formed by the distannane method.
1
forded 29 as white crystals (2.2 g, 50%): mp 170-172 °C; H
NMR (200 MHz, CDCl3) δ 2.23 (s, 6H), 1.61 (s, 9H); MS (m/e)
352 (M+, 35), 252 (100), 216 (73); IR (KBr) 3400 (s), 2990 (m),
1540 (m), 1380 (m), 1310 (m), 1120 (s) cm-1. Anal. Calcd for
C
13H15NS2Cl2O2: N, 3.97; S, 18.18; Cl, 20.17. Found: N, 3.66;
S, 18.45; Cl, 19.85.
4,5,6-Tr im eth yl-2-th ioxo-1,3-d ith iolo[4,5-c]p yr r ole (30).
This was prepared from 23 by the LAH reduction procedure
as a yellow solid in 65% yield: mp 142-144 °C; 1H NMR (360
MHz, CDCl3) δ 3.48 (s, 3H), 2.23 (s, 6H); 13C NMR (90 MHz,
CDCl3) δ 218.63, 118.68, 118.39, 31.32, 12.12; IR (CDCl3) 3020
(s), 2910 (m), 1560 (m), 1480 (m), 1060 (s) cm-1. Anal. Calcd
for C8H9NS3: C, 44.65; H, 4.18; N, 6.51; S, 44.65. Found: C,
44.49; H, 4.23; N, 6.44; S, 44.51.
(b) Bis(2,5-d im eth yl-N-p h en ylp yr r olo[3,4-d ])tetr a th i-
a fu lva len e (7). 53% yield. The physical and spectroscopic
data were identical to those of the material formed by the
distannane method.
Gen er a l P r oced u r e for Deth ion a tion by Mer cu r ic
Dia ceta te. (a ) 5-ter t-Bu toxyca r bon yl-4,6-d im eth yl-2-oxo-
1,3-d ith iolo[4,5-c]p yr r ole (31). To a solution of (15) (1.59
g, 4.98 mmol) in CHCl3 (8 mL) was added mercuric diacetate
(2.38 g, 7.47 mmol) in aqueous methanol (8 mL) and acetic
acid (1.5 mL) at rt. The reaction mixture was stirred for 3 h,
and the precipitate was then filtered off through a Celite-
packed funnel under aspirator suction, the Celite being then
washed with chloroform (30 mL). The filtrate was washed
with saturated sodium bicarbonate, water, and brine and dried
over sodium sulfate. Upon concentration under reduced
pressure, the residue was purified by chromatography on silica
gel (30.0 g) using CH2Cl2/hexane (3:1) as the eluent to afford
the product (1.30 g, 92%) as a colorless solid. The crude
product was purified by crystallization from methanol: mp
(c) Bis(2,5-d im eth yl-N-m eth ylp yr r olo[3,4-d ])tetr a th i-
a fu lva len e (9). 55% yield, yellow microcrystals: mp > 250
1
°C; H NMR (360 MHz, CDCl3) δ 3.34 (s, 6H), 2.13 (s, 12H);
13C NMR (90 MHz, CDCl3) δ 120.15, 118.63, 114.42, 30.98,
11.99; IR (CDCl3) 3040 (s), 2995 (m), 1760 (m), 1540 (m), 1440
(m) cm-1. Anal. Calcd for C16H18N2S4: C, 52,46; H, 4.91; N,
7.65; S, 34.97. Found: C, 52.49; H, 4.98; N, 7.65; S, 34.90.
Bis(2,5-d im eth ylp yr r olo[3,4-d ])tetr a th ia fu lva len e (8).
A solution of BOC-TTF 6 (1.62 g, 3.01 mmol) in dry DMF
(120 mL) was degassed by a nitrogen stream for 15-20 min.
To this solution was added 30% sodium methoxide in methanol
(2.87 mL, 15.05 mmol) at rt, and the mixture was stirred under
nitrogen for 12 h. Water (10 mL) was added, and the solvents
were partially removed under reduced pressure. An additional
10 mL of water was added, and the resulting precipitate was
collected by filtration and washed with methanol (15 mL) to
give the product (1.05 g, 99%) as yellow crystals: mp > 250
°C; 1H NMR (360 MHz, DMSO-d6) δ 10.60 (s, 2H), 2.08 (s,
12H); 13C NMR (90 MHz, DMSO-d6) δ 124.51, 122.16, 118.44,
17.22; IR (KBr) 3230 (s), 2930 (s), 1620 (m), 1460 (m), 1375
(m), 1159 (s), 870 (s), 785 (m) cm-1; MS (m/e) 338 (M+, 100),
314 (12), 213 (53), 169 (13). Anal. Calcd for C14H14N2S4: C,
49.70; H, 4.28; N, 8.28; S, 37.86. Found: C, 49.61; H, 4.35; N,
8.10; S, 37.62.
1
185-187 °C; H NMR (360 MHz, CDCl3) δ 2.41 (s, 6H), 1.61
(s, 9H); 13C NMR (90 MHz, CDCl3) δ 220.43, 149.32, 122.78,
114.67, 84.72, 28.07, 16.52; IR (KBr) 3215 (s), 3050 (m), 1645
(m), 1450 (m), 1105 (m), 970 (m), 860 (m) cm-1; MS (m/e) 285
(M+, 28), 257 (36), 185 (100), 157 (45), 156 (58), 112 (19), 93
(24). Anal. Calcd for
Found: N, 4.86; S, 22.72.
C12H15NO3S2: N, 4.91; S, 22.45.
(b) 4,6-Dim eth yl-5-p h en yl-2-oxo-1,3-d ith iolo[4,5-c]p yr -
r ole (32). This was obtained in 90% yield as pale yellow
crystals: mp 185-187 °C; 1H NMR (360 MHz, CDCl3) δ 7.61-
7.48 (m, 3H), 7.32-7.16 (m, 2H), 2.10 (s, 6H); 13C NMR (90
MHz, CDCl3) δ 195.77, 137.54, 129.45, 128.61, 128.15, 121.15,
109.32, 12.72; IR (CDCl3) 3040 (s), 2045 (m), 1730 (s), 1660
Bis(2,5-d im eth yl-N-m eth ylp yr r olo[3,4-d ])tetr a th ia fu l-
va len e (9). This compound was obtained from 8 by the
general procedure for N-alkylation (99% yield). All of the
physical and spectroscopic data were identical to those of the
compound obtained by the coupling reaction in triethyl phos-
phite.
(s), 1520 (s), 1400 (s), 1250 (m) cm-1. Anal. Calcd for C13H11
-
NOS2: C, 59.77; H, 4.21; N, 5.36; S, 24.52. Found: C, 59.75;
H, 4.25; N, 5.41; S, 24.61.
(c) 4,5,6-Tr im eth yl-2-oxo-1,3-d ith iolo[4,5-c]p yr r ole (33).
Bis(2,5-dim eth yl-N-octadecan ylpyr r olo[3,4-d])tetr ath i-
a fu lva len e (10). This compound was obtained from 8 by the
general procedure for N-alkylation (99% yield) as yellow
This was obtained in 90% yield as pale yellow crystals: mp
1
96-98 °C; H NMR (360 MHz, CDCl3) δ 3.46 (s, 3H), 2.23 (s,
6H); 13C NMR (90 MHz, CDCl3) δ 196.15, 120.31, 107.87, 30.91,
12.31; IR (CDCl3) 3030 (s), 1680 (s), 1650 (m), 1450 (m), 1380
(m), 1050 (m) cm-1. Anal. Calcd for C8H9NOS2: C, 48.24; H,
4.52; N, 7.03; S, 32.16. Found: C, 48.32; H, 4.55; N, 6.97; S,
32.26.
crystals: mp 126-128 °C; H NMR (360 MHz, CDCl3) δ 3.65
1
(m, 4H), 2.15 (s, 12H), 1.60-1.15 (m, 64H), 0.90 (t, J ) 6.58
Hz, 6H); 13C NMR (90 MHz, DMSO-d6) δ 117.82, 115.00,
114.68, 44.47, 31.91, 31.50-27.00 (13C), 26.77, 22.68, 14.10,
11.99; IR (CDCl3) 2980 (s), 2270 (m), 1470 (s), 1420 (s), 1390

8124 J . Org. Chem., Vol. 61, No. 23, 1996
Zong et al.
(s), 1100 (m) cm-1. Anal. Calcd for C50H86N2S4: C, 71.25; H,
10.21; N, 3.32; S, 15.20. Found: C, 71.16; H, 10.27; N, 3.25;
S, 15.29.
Com p lex of Don or 8 w it h TCNQ. Anal. Calcd for
C26H18N6S4: C, 57.54; H, 3.34; N, 15.48; S, 23.63. Found: C,
57.66; H, 3.39; N, 15.37; S, 23.52.
Gen er a l P r oced u r e for th e P r ep a r a tion of Ch a r ge-
Tr a n sfer Com p lexes. A degassed hot solution of the donor
(1.0 equiv) in acetonitrile was treated with a hot acetonitrile
solution of TCNQ (1.0 equiv). The resulting green solution
was allowed to cool to rt very slowly (which was accomplished
by wrapping the flask with cotton or glass wool). After 3-4
h, the green charge-transfer complex crystals were collected
by vacuum filtration.
Com p lex of Don or 9 w it h TCNQ. Anal. Calcd for
26H18N6S4: C, 58.92; H, 3.89; N, 14.72; S, 22.47. Found: C,
58.67; H, 3.96; N, 14.53; S, 22.67.
C
Ack n ow led gm en t. We thank the National Science
Foundation (Grant CHE9224899) for support of this
work.
Com p lex of Don or 7 w it h TCNQ. Anal. Calcd for
C38H26N6S4: C, 65.68; H, 3.77; N, 12.09; S, 18.45. Found: C,
65.69; H, 3.83; N, 12.01; S, 18.44.
J O961282H