Umpolung of the 5-alkyl-2-dimethylamino-1,3-dithiolium-4-thiolate mesoion and its application in the synthesis of some new tetrathiafulvalenes

Article abstract of DOI:10.1002/ejoc.200300672

The 5-alkyl-2-dimethylamino-1,3-dithiolium-4-thiolate mesoion could be umpoled with sulfuryl chloride to yield a dicationic electrophile 3 that reacted with various electron-rich aromatic substrates to yield arylthio-substituted 1,3-dithiolium salts 13-25. Two of these compounds have been transformed to the corresponding symmetrical tetrathiafulvalenes 43 and 44, and their cyclovoltammetric behaviour recorded. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.

Full text of DOI:10.1002/ejoc.200300672

FULL PAPER
Umpolung of the 5-Alkyl-2-dimethylamino-1,3-dithiolium-4-thiolate Mesoion
and Its Application in the Synthesis of Some New Tetrathiafulvalenes
Jonas Hellberg,*[a] Emma Dahlstedt,[a] and Andreas Woldegiorgis[b]
Keywords: Umpolung / Mesoion / 1,3-Dithiolium ion / Tetrathiafulvalene / Cyclic voltammetry
The 5-alkyl-2-dimethylamino-1,3-dithiolium-4-thiolate me-
soion could be umpoled with sulfuryl chloride to yield a di-
cationic electrophile 3 that reacted with various electron-rich
aromatic substrates to yield arylthio-substituted 1,3-dithiol-
formed to the corresponding symmetrical tetrathiafulvalenes
43 and 44, and their cyclovoltammetric behaviour recorded.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
ium salts 13−25. Two of these compounds have been trans- Germany, 2004)
Introduction
We speculated that structures of type 3 would react with
electron-rich nucleophiles, thereby providing a new way to
synthesize TTFs substituted with a variety of electron-rich
structures. Furthermore, since the alkyl group in the 5-posi-
tion can be easily varied, and also be replaced by aromatic
systems (e.g. naphthalene), it should be possible to con-
struct donor structures containing several different as-
sembled π-systems.
We would herein like to report our results from the reac-
tions of electrophilic agents of type 3 with a number of
electron-rich aromatics, together with elaboration to the
corresponding symmetrical TTFs. The electrochemical
properties of these TTFs are also presented.
Tetrathiafulvalenes (TTFs) (1) have received a lot of
interest during the last two decades due to their ability to
act as π-donors in charge-transfer salts and cation radical
salts, which show metallic and even superconducting behav-
iour.[1] Their synthesis has been reviewed.[2] One of the stra-
tegies used to construct the TTF skeleton has been to utilize
the readily available 5-alkyl-2-dialkylamino-1,3-dithiolium-
4-thiolate mesoion (2), as first described by Robert et al.,[3]
and later by other groups.[4] These mesoions have also been
used as starting materials for making dithiadiazafulval-
enes,[5] as well as 1,4-dithiafulvenes[6] and other extended
π-systems.[7]
There are, however, no previous examples of attempts to
transform mesoions of type 2 to electrophiles with the gen- Results and Discussion
eric structure 3 by umpolung of the thiolate anion.
The reaction sequence we used is illustrated in Scheme 1.
The 5-alkyl-2-dimethylamino-1,3-dithiolium-4-thiolate me-
soions 2aϪc could be conveniently umpoled with sulfuryl
chloride in dichloromethane at room temperature. The re-
sulting intermediates 3aϪc[8] were treated with the nucle-
ophile in situ. The progress of the reaction could be moni-
Scheme 1. Reagents and conditions: (i) SO2Cl2, CH2Cl2, room temp.; (ii) Substrate: R2; (iii) KPF6, H2O, room temp.
[a]
[b]
Department of Chemistry, Organic Chemistry, Royal Institute
of Technology,
Teknikringen 56, 10044 Stockholm, Sweden
Department of Chemistry, Analytical Chemistry, Royal
Institute of Technology,
Teknikringen 36, 10044 Stockholm, Sweden
Fax: (internat.) ϩ46-8-791-2333
E-mail: jhel@kth.se
tored by TLC, and was usually complete overnight, yielding
the chloride salt. These products were dissolved in water
and precipitated with KPF6 to give the corresponding hexa-
fluorophosphonium salts 13Ϫ25 (Table 1). This reprecipi-
tation led to pure, crystalline salts, which were stable at am-
bient temperature and atmosphere.
Eur. J. Org. Chem. 2004, 1455Ϫ1463
DOI: 10.1002/ejoc.200300672
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J. Hellberg, E. Dahlstedt, A. Woldegiorgis
FULL PAPER
Table 1. In situ electrophilic aromatic substitution with an umpoled mesoion[a]
[a]
[b]
Reagents and conditions: (i) SO2Cl2, CH2Cl2, room temp.; (ii) substrate: R2; (iii) KPF6, H2O, room temp.
Yield of isolated pure
product based on substrate R2. Product not analytically pure.
[c]
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Umpolung of the 5-Alkyl-2-dimethylamino-1,3-dithiolium-4-thiolate Mesoion
FULL PAPER
According to the described procedure, three mesoions
2aϪc with different alkyl chain-lengths, were treated with a
variety of aromatic substrates (Table 1).
As shown in Table 1, the electrophilic intermediate 3 adds
to electron-rich phenols such as dihydrobenzo[1,4]dioxin-6-
ol (4), sesamol (5) and p-methoxyphenol (6), yielding the
ride (Table 2). The products 27Ϫ38 were obtained in almost
quantitative yield, either as oils or crystalline compounds.
The oily products were not stable at ambient temperature
and were best used as soon as possible. The crystalline com-
pounds were somewhat more stable.[10]
Deamination of the amino compounds was carried out
by use of hexafluorophosphoric acid,[11] giving the four di-
thiolium salts 39Ϫ42 in moderate yield (60Ϫ70%).
products 13Ϫ17. With p-methoxyphenol (6), synthesis of
both mono- and disubstituted products (16 and 17) could
be achieved, depending on the amount of electrophile used.
However, total conversion into compound 17 could not be
accomplished, since the reaction stopped at the monosub-
stituted product 16. Even with prolonged reaction times,
elevated temperatures and an increased amount of electro-
phile, the reaction could not be driven to completion. Un-
fortunately, we were not able to separate the products in
order to attain analytically pure 17.
The electrophile 3 reacted with 2,6-dihydroxynaphthalene
(7) and 2,6-dimethoxynaphthalene (8), yielding in the for-
mer case the 1,5-disubstituted products 18 and 19, whereas
in the latter case, only the monosubstituted product 20 was
produced. We also tried substitution with 1,5-dihydroxyna-
phthalene, but this only resulted in oxidation of the start-
ing material.
Heteroaromatic systems such as indole and electron-rich
thiophenes were also tried. Indole (9) and N-methylindole
(10) were substituted in the 3-position to give 21 and 22.
Whereas 3-methoxythiophene (11) also yielded the mono-
substituted products 23 and 24, 3,4-dimethoxythiophene
(12) gave the disubstituted product 25. In the cases where
an additional quantity of electrophile was needed to in-
crease the conversion of starting material, the electrophile
seemed to form a stable compound with sulfuryl chloride,
From these salts, we could isolate the corresponding
tetrathiafulvalenes 43, 44 and 45 after treatment with tri-
ethylamine. We were able to characterize 43 and 44 fully,
but unfortunately TTF 45 could only be identified by MS
(EI), because decomposition during column chromatogra-
phy prevented it being obtained in analytical purity. TTF
43 was obtained in 35% yield after purification, whereas
TTF 44 resulted only in 16% yield. We could not detect any
TTF from the reaction of 41 with triethylamine.[12]
1
rather than with the substrate. H NMR spectroscopy and
MS (EI) confirmed the structure of this product as the di-
mer 26.[9] This problem could not be overcome by use of
an inert atmosphere, prolonged reaction time or elevated
temperatures. Addition of the substrate before the sulfuryl
chloride resulted (in some cases) in chlorination of the sub-
strate prior to umpolung of the mesoion 2.
Once prepared, the 4-arylthio-2-(dialkylimino)-1,3-dithi-
olium salts could then be used in the synthesis of TTFs,
according to the procedure outlined in Scheme 2.
The electrochemical behaviour of the TTFs 43 and 44
was investigated by cyclic voltammetry (CV) in dichloro-
methane; the results are shown in Figures 1 and 2.
The cyclic voltammograms indicated the presence of two
The salts 13Ϫ16 and 18Ϫ25 were reduced to the corre- reversible one-electron transfer processes, corresponding to
sponding amino compounds 27Ϫ38 with sodium borohyd- the successive formation of the cation radical (E1) and di-
Scheme 2. Reagents and conditions: (i) NaBH4, EtOH, room temp.; (ii) HPF6, H2SO4, 0 °C; (iii) Et3N, CH3CN, N2, room temp.
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J. Hellberg, E. Dahlstedt, A. Woldegiorgis
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Table 2. Synthesis of compounds 27Ϫ38 from reduction[a] of the 2-(dialkylimino)-4-arylthio-1,3-dithiolium salts 13Ϫ16 and 18Ϫ25
[a]
Reagents and conditions: NaBH4, EtOH, room temp.
whereas the reductions of naphthalene-TTF 43 were less
affected, as can be seen in Figure 2.
Figure 1. Cyclic voltammograms of TTFs 43, 44 and 47 (0.1  in
CH2Cl2), 1 m (nBu)4NClO4, scan rate 500 mV sϪ1, E vs. SCE
cation (E2), as expected for TTFs. The compounds also
showed a third irreversible oxidation potential (Figure 1),
possibly due to additional oxidation of the aromatic sub-
stituents. The first and second reduction waves of indole-
TTF 44 were severely perturbed by the third oxidation,
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Umpolung of the 5-Alkyl-2-dimethylamino-1,3-dithiolium-4-thiolate Mesoion
FULL PAPER
Figure 2. Cyclic voltammograms of TTFs 43 and 44 (0.1  in CH2Cl2), 1 m (nBu)4NClO4, scan rate 500 mV sϪ1, E vs. SCE
We expected that the sulfur bridge between the TTFs and chloride (Scheme 3). Compound 47 could then be treated
the aromatic substituents would not completely disrupt the with various electron-rich aromatic compounds.
conjugation within the molecule, but allow electronic
‘‘cross-talk’’ between the π-systems within the molecules,
thereby lowering the oxidation potential. However, we can-
not detect such an inductive behaviour in the potentials
measured (which are quite normal), but the potentials are
a little lower than for the corresponding bis(benzylthio)-
substituted TTF 47 (see Figure 1), as shown in Table 3.
Scheme 3. Attempted synthesis of a dicationic electrophile. Re-
agents and conditions: (i) SO2Cl2, CH2Cl2, room temp.
Table 3. Electrochemical data for TTFs 43, 44 and 47 (0.1  in
CH2Cl2), [1 m (nBu)4NClO4, scan rate 500 mV sϪ1, E vs. SCE]
Preliminary results from reactions of 47 with sesamol (9)
E1 (V)
E2 (V)
∆E ϭ E2 Ϫ E1 (V)
as substrate gave a number of products, of which we could
identify compound 49 (by NMR spectroscopy and MS), as
well as the chlorinated by-product 50. The result is similar
when two or four equivalents of sulfuryl chloride are used.
We could not detect any non-benzylated 49 in the reaction
mixtures, which led us to the hypothesis that the benzyl-
ation of the hydroxy function is occurring at the same time
as the electrophilic attack of the sulfur. Further investi-
gations of this reaction will be performed and reported in
due course.
43
44
47
0.38
0.37
0.43
0.76
0.75
0.81
0.39
0.38
0.38
Whether the electrochemical behaviour of indole-TTF 44
reflects a less stable tricationic species, a more effective
cross-talk of the same state, or is a consequence of the vis-
ible precipitation on the anode, remains undecided.
The first attempts at electrocrystallization of 43 were per-
formed in the presence of four different counterions
(nBu)4NClO4, (nBu)4NBF4, (nBu)4NPF6, and (nBu)4N-
AsF6. So far, however, we have only obtained polycrystal-
line material.
Conclusions
An alternative and more reliable way to achieve the syn-
We have demonstrated that the 5-alkyl-2-dimethylamino-
thesis of arylthio-substituted TTFs could be to prepare the 1,3-dithiolium-4-thiolate mesoion 2 can be umpoled to the
TTF bis(sulfenyl chloride) 48 in situ by the debenzylation electrophile 3, and utilized in reactions with various elec-
of the bis(benzylthio)-substituted TTF 47 with sulfuryl tron-rich aromatics. Three of the resulting dithiolium salts
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J. Hellberg, E. Dahlstedt, A. Woldegiorgis
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125.2, 140.5, 144.2, 150.0, 153.5, 184.0 ppm. C14H16F6NO3PS3:
calcd. C 34.50, H 3.31; found C 34.47, H 3.36.
13Ϫ25 have been transformed to the corresponding sym-
metrical tetrathiafulvalenes in three steps. Further appli-
cations of these electron-rich donor molecules are now be-
ing investigated.
15: Yield: 75% (6.80 g); pink crystals. M.p. 187.7Ϫ188.4 °C. 1H
NMR (400 MHz, [D6]DMSO): δ ϭ 2.54 (s, 3 H), 3.41 (s, 3 H), 3.44
(s, 3 H), 5.99 (s, 2 H), 6.56 (s, 1 H), 6.99 (s, 1 H), 10.31 (br. s, 1 H)
ppm. 13C NMR (100 MHz, [D6]DMSO): δ ϭ 15.2, 46.6, 47.0, 98.0,
106.3, 112.4, 125.7, 137.9, 140.5, 149.9, 153.3, 183.9 ppm.
C13H14F6NO3PS3: calcd. C 32.98, H 2.98; found C 32.90, H 3.02.
Experimental Section
General Remarks: All operations (except where indicated) were per-
formed under ambient conditions, without any special care taken
for the exclusion of air or moisture. 1H NMR and 13C NMR spec-
tra were recorded with a Bruker AM 400 (400 MHz) or Bruker
DMX 500 (500 MHz) spectrometer. Mass spectra were recorded
with a Finnigan SSQ 7000 (electron impact) or a Bruker Reflex III
(MALDI-TOF) MS instrument. Elemental analyses were per-
formed by Analytische Laboratorien GmbH, Germany. THF was
freshly distilled from sodium benzophenone ketyl. Mesoions 2a, 2b
and 2c and compound 47 were prepared in accordance to previous
reported procedures.[4b] All other commercial reagents and solvents
were used as received. Cyclic voltammetry was carried out at ambi-
ent temperature in dichloromethane at 500 mV·sϪ1 with tetrabu-
tylammonium perchlorate (0.1 ) as the electrolyte and a SCE ref-
erence electrode. The half-wave potential for the ferrocene/ferrocen-
ium couple was found to be 0.49 V in our system. Electrocrystalliz-
ation was carried out in a U-shaped electrocrystallization cell. The
donor (20 mg) was put in the anode compartment and separated
from the cathode compartment by a porous glass frit. Dry di-
chloromethane (40 mL) was added, together with the electrolyte
(0.1 ), and the compartments were degassed with nitrogen. The
experiments were carried out at ambient temperature, with a plati-
num wire anode of about 1 cm2. Currents used were 1.0 µA·cmϪ2
at the beginning of each experiment and increased to 4 µA·cmϪ2
over a period of 15 days.
16: Yield: 64% (0.67 g); beige crystals. M.p. 139.5Ϫ141.3 °C. 1H
NMR (400 MHz, [D6]DMSO): δ ϭ 2.54 (s, 3 H), 3.44 (s, 3 H), 3.47
(s, 3 H), 3.67 (s, 3 H), 6.77 (d, J ϭ 2.5 Hz, 1 H), 6.85 (d, J ϭ
2.5 Hz, 1 H), 6.86 (d, J ϭ 0.8 Hz, 1 H), 10.00 (s, 1 H) ppm. 13C
NMR (100 MHz, [D6]DMSO): δ ϭ 15.3, 46.6, 47.0, 55.5, 115.5,
116.2, 116.5, 118.1, 123.0, 141.0, 149.9, 152.5, 183.9 ppm.
C13H16F6NO2PS3: calcd. C 33.99, H 3.51; found C 33.74, H 3.40.
17: Yield: 26% (0.945 g); yellow crystals. The product was not ana-
lytically pure and could not be separated from the monosubstituted
1
p-methoxyphenol 16. H NMR (400 MHz, [D6]DMSO): δ ϭ 2.55
(s, 6 H), 3.46 (s, 6 H), 3.49 (s, 6 H), 3.70 (s, 3 H), 6.73 (2 H) ppm.
18: Yield: 74% (0.65 g); beige crystals. M.p. 238.0Ϫ240.0 °C. 1H
NMR (400 MHz, [D6]DMSO): δ ϭ 2.65 (s, 6 H), 3.29 (s, 6 H), 3.39
(s, 6 H), 7.44 (d, J ϭ 9.3 Hz, 2 H), 8.44 (d, J ϭ 9.3 Hz, 2 H), 11.00
(s, 2 H) ppm. 13C NMR (100 MHz, [D6]DMSO): δ ϭ 15.4, 46.6,
46.9, 108.8, 120.1, 125.6, 128.4, 130.0, 136.1, 156.3, 183.8 ppm.
C22H24F12N2O2P2S6: calcd. C 31.81, H 2.91; found C 31.52, H
3.06.
19: Yield: 63% (0.59 g); brown crystals. 1H NMR (400 MHz,
[D6]DMSO): δ ϭ 0.86 (t, J ϭ 7.3 Hz, 6 H), 1.20Ϫ1.30 (m, 28 H),
1.50Ϫ1.57 (m, 4 H), 3.07 (t, J ϭ 7.5 Hz, 4 H), 3.30 (s, 6 H), 3.40
(s, 6 H), 7.42 (d, J ϭ 9.1 Hz, 2 H), 8.43 (d, J ϭ 9.1 Hz, 2 H), 11.02
(s, 2 H) ppm. 13C NMR (100 MHz, CDCl3): δ ϭ 14.1, 22.6, 29.0,
29.1, 29.2, 29.4, 29.5, 30.2, 31.7, 31.8, 46.5, 46.9, 109.1, 117.1,
120.5, 127.1, 130.3, 139.9, 155.9, 185.2 ppm. C40H60F12N2O2P2S6:
calcd. C 44.35, H 5.58; found C 44.50, H 5.76.
General Procedure for the Formation of 4-Arylthio-2-(dialkylimino)-
1,3-dithiolium Hexafluorophosphates 13؊25 from the Reaction of a
Nucleophilic Substrate with the in situ Generated Electrophile
Preparation of 13: Mesoion 2a (10 mmol) was dissolved in CH2Cl2
(80 mL) in a round-bottomed flask, which was flushed with N2.
SO2Cl2 (1.35 g, 10 mmol) was added dropwise, to give a light yellow
solution. Substrate 4 (10 mmol) was dissolved in CH2Cl2 (40 mL)
and added to the mixture; the reaction was monitored by TLC
analysis. When the reaction was complete, the solvent was evapo-
rated, yielding the chloride salt, which was then dissolved in H2O
(100 mL). A solution of KPF6 (5 g) in H2O (100 mL) was added
to the solution; a yellow precipitate formed immediately. The pre-
cipitate was filtered off, washed with H2O and then dissolved in
CH2Cl2. This solution was dried with MgSO4, and the solvent was
removed under reduced pressure, yielding 13. Yield: 78% (3.10 g);
apricot crystals. M.p. 165.3Ϫ167.0 °C. 1H NMR (400 MHz,
[D6]DMSO): δ ϭ 1.22 (t, J ϭ 7.5 Hz, 3 H), 3.01 (q, J ϭ 7.5 Hz, 2
H), 3.42 (s, 3 H), 3.45 (s, 3 H), 4.14Ϫ4.17 (m, 2 H), 4.20Ϫ4.23 (m,
2 H), 6.45 (s, 1 H), 6.90 (s, 1 H), 10.11 (s, 1 H) ppm. 13C NMR
(100 MHz, [D6]DMSO): δ ϭ 14.7, 23.1, 46.7, 47.1, 63.6, 64.5,
104.3, 107.9, 121.1, 124.7, 136.7, 144.8, 145.7, 151.7, 184.0 ppm.
C15H18F6NO3PS3: calcd. C 35.93, H 3.62; found C 35.65, H 3.62.
20: Yield: 75% (3.91 g); pale yellow crystals. M.p. 218.9Ϫ220.8 °C.
1H NMR (400 MHz, [D6]DMSO): δ ϭ 2.64 (s, 3 H), 3.30 (s, 3 H),
3.38 (s, 3 H), 3.87 (s, 3 H), 4.00 (s, 3 H), 7.36 (dd, J ϭ 9.3 Hz,
2.5 Hz, 1 H), 7.42 (d, J ϭ 2.5 Hz, 1 H), 7.55 (d, J ϭ 9.1 Hz, 1 H),
8.07 (d, J ϭ 9.1 Hz, 1 H), 8.32 (d, J ϭ 9.3 Hz, 1 H) ppm. 13C
NMR (100 MHz, [D6]DMSO): δ ϭ 15.3, 46.6, 46.9, 55.3, 56.7,
107.1, 110.6, 114.3, 121.0, 125.1, 125.3, 129.6, 130.1, 132.1, 136.8,
156.0, 157.1, 183.6 ppm. C18H20F6NO2PS3: calcd. C 41.30, H 3.85;
found C 41.09, H 3.87.
21: Yield: 74% (0.40 g); pale yellow crystals. M.p. 165.8Ϫ166.7 °C.
1H NMR (400 MHz, [D6]DMSO): δ ϭ 2.63 (s, 3 H), 3.30 (s, 3 H),
3.38 (s, 3 H), 7.18 (t, J ϭ 7.8 Hz, 1 H), 7.23 (t, J ϭ 7.8 Hz, 1 H)
7.50 (d, J ϭ 7.8 Hz, 1 H), 7.59 (d, J ϭ 7.8 Hz, 1 H), 7.94 (d,
J ϭ 3.0 Hz, 1 H), 11.88 (br. s, 1 H) ppm. 13C NMR (100 MHz,
[D6]DMSO): δ ϭ 15.0, 46.6, 47.0, 98.9, 112.6, 117.7, 120.8, 122.7,
127.8, 128.6, 132.9, 133.3, 136.3, 183.3 ppm. C14H15F6N2PS3:
calcd. C 37.16, H 3.34; found C 36.78, H 3.42.
22: Yield: 76% (1.77 g); pale yellow crystals. M.p. 159.5Ϫ161.4 °C.
1H NMR (400 MHz, [D6]DMSO): δ ϭ 2.63 (s, 3 H), 3.31 (s, 3 H),
3.37 (s, 3 H), 3.85 (s, 3 H), 7.23 (t, J ϭ 7.8 Hz, 1 H), 7.30 (t, J ϭ
8.3 Hz, 1 H) 7.57 (d, J ϭ 8.3 Hz, 1 H), 7.60 (d, J ϭ 7.8 Hz, 1 H),
7.95 (s, 1 H) ppm. 13C NMR (100 MHz, [D6]DMSO): δ ϭ 15.1,
Compounds 14Ϫ25 were prepared in the above manner.
14: Yield: 88% (9.60 g); white crystals. M.p. 168.8Ϫ169.8 °C. 1H
NMR (400 MHz, [D6]DMSO): δ ϭ 1.22 (t, J ϭ 7.5 Hz, 3 H), 3.01
(q, J ϭ 7.5 Hz, 2 H), 3.41 (s, 3 H), 3.45 (s, 3 H), 5.99 (s, 2 H), 6.56
(s, 1 H), 7.00 (s, 1 H), 10.35 (br. s, 1 H) ppm. 13C NMR (100 MHz, 33.0, 46.6, 47.0, 97.7, 111.0, 118.0, 121.1, 122.7, 128.2, 133.8, 136.4,
[D6]DMSO): δ ϭ 14.7, 23.1, 46.7, 47.1, 98.0, 101.7, 106.2, 112.4, 137.0, 183.3 ppm.
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23: Yield: 77% (5.56 g); brown oil. M.p. 158.5Ϫ160.5 °C. 1H NMR
(400 MHz, [D6]DMSO): δ ϭ 2.56 (s, 3 H), 3.42 (s, 3 H), 3.43 (s, 3
H), 5.75 (s, 1 H), 5.76 (s, 1 H), 6.87 (br. s, 2 H), 7.30 (d, J ϭ 9.1 Hz,
1 H), 7.31 (d, J ϭ 9.1 Hz, 1 H), 8.28 (d, J ϭ 9.1 Hz, 1 H), 8.29 (d,
H), 3.92 (s, 3 H), 7.16 (d, J ϭ 5.8 Hz, 1 H), 7.83 (d, J ϭ 5.8 Hz, 1 J ϭ 9.1 Hz, 1 H) ppm. 13C NMR (100 MHz, CDCl3): δ ϭ 15.4,
H) ppm. 13C NMR (100 MHz, [D6]DMSO): δ ϭ 15.1, 46.7, 47.1,
37.9, 77.8, 110.8, 114.5, 118.0, 128.9, 129.7, 130.6, 154.8 ppm. MS
59.1, 102.0, 117.0, 126.2, 131.8, 137.4, 161.5, 183.5 ppm. (MALDI-TOF): m/z ϭ 541.66 [Mϩ].
C11H14F6NOPS4: calcd. C 29.39, H 3.14; found C 29.29, H 3.17.
32: Yield: 99% (0.28 g); brown oil. 1H NMR (400 MHz,
[D6]DMSO): δ ϭ 0.81Ϫ0.89 (m, 6 H), 1.23Ϫ1.34 (m, 28 H),
24: Yield: 70% (1.56 g); brown oil. 1H NMR (400 MHz,
[D6]DMSO): δ ϭ 0.86 (m, 3 H), 1.21Ϫ1.38 (m, 14 H), 1.58Ϫ1.65 1.41Ϫ1.53 (m, 8 H), 1.87 (s, 12 H), 6.03 (s, 2 H), 7.21 (d, J ϭ
(m, 2 H), 3.00 (t, J ϭ 7.3 Hz, 2 H), 3.42 (s, 3 H), 3.44 (s, 3 H), 3.92 9.1 Hz, 2 H), 8.24 (d, J ϭ 9.1 Hz, 1 H), 8.25 (d, J ϭ 9.1 Hz, 1
(s, 3 H), 7.17 (d, J ϭ 5.8 Hz, 1 H), 7.84 (d, J ϭ 5.8 Hz, 1 H) ppm.
13C NMR (100 MHz, [D6]DMSO): δ ϭ 13.9, 22.1, 28.2, 28.5, 28.6,
28.8, 28.9, 29.1, 29.7, 31.2, 46.8, 47.1, 59.0, 101.7, 117.0, 126.2,
132.0, 142.1, 161.6, 183.6 ppm.
H),10.04 (br. s, 2 H) ppm. MS (MALDI-TOF): m/z ϭ 792.27
[Mϩ Ϫ2H].
33: Yield: 94% (2.48 g); orange crystals. M.p. 96.5Ϫ97.9 °C. 1H
NMR (400 MHz, [D6]DMSO): δ ϭ 1.85 (s, 6 H), 2.29 (s, 3 H), 3.86
(s, 3 H), 3.89 (s, 3 H), 6.02 (s, 1 H), 7.26 (dd, J ϭ 9.3 Hz, 2.8 Hz,
1 H), 7.33 (d, J ϭ 2.8 Hz, 1 H), 7.43 (d, J ϭ 9.1 Hz, 1 H), 7.94 (d,
J ϭ 9.1 Hz, 1 H), 8.32 (d, J ϭ 9.3 Hz, 1 H) ppm. 13C NMR
(100 MHz, [D6]DMSO): δ ϭ 15.3, 37.2, 55.2, 56.3, 76.5, 106.6
25: Yield: 68% (1.39 g); white crystals. M.p. 160.7Ϫ162.5 °C. 1H
NMR (500 MHz, [D6]DMSO): δ ϭ 2.59 (s, 6 H), 3.45 (s, 6 H), 3.46
(s, 6 H), 3.98 (s, 6 H) ppm. 13C NMR (125 MHz, [D6]DMSO):
δ ϭ 15.5, 46.9, 47.3, 61.3, 115.1, 123.2, 141.0, 152.4, 183.4 ppm.
C18H24F12N2O2P2S7: calcd. C 26.53, H 2.97; found C 26.50, H 113.3 113.9, 115.2, 119.9, 126.0, 129.7, 129.8, 130.4, 130.5, 155.6,
3.00.
156.8 ppm. MS (EI): m/z (%) ϭ 379.2 (20) [Mϩ].
Reduction of the Hexafluorophosphate Salts 13؊16 and 18؊25 to 34: Yield: 88% (0.20 g); orange oil. 1H NMR (400 MHz,
the Corresponding Amino Products 27Ϫ38
[D6]DMSO): δ ϭ 1.91 (s, 6 H), 2.27 (s, 3 H), 6.05 (s, 1 H), 7.09 (t,
J ϭ 7.8 Hz, 1 H), 7.15 (t, J ϭ 8.0 Hz, 1 H) 7.42 (d, J ϭ 8.0 Hz, 1
H), 7.54 (d, J ϭ 7.8 Hz, 1 H), 7.62 (d, J ϭ 2.8 Hz, 1 H) ppm. 13C
NMR (100 MHz, [D6]DMSO): δ ϭ 15.3, 30.7, 37.4, 76.3, 101.8,
112.1, 117.8, 118.3, 119.8, 121.9, 128.1, 128.5, 131.2, 136.1 ppm.
MS (MALDI-TOF): m/z ϭ 307.10 [Mϩ Ϫ H].
Preparation of 27: 13 (8.2 mmol) was dissolved in 99% EtOH
(80 mL). NaBH4 (40.8 mmol) was added over a period of 5 mi-
nutes. After stirring at room temp for 1 h, 10% aqueous NH4Cl
and Et2O (or CH2Cl2) were added and the layers separated. The
organic phase was washed with H2O, dried with MgSO4, filtered
and the solvents evaporated to dryness, yielding 27. This product
1
35: Yield: 98% (0.70 g); dark orange crystals. H NMR (400 MHz,
was used without further purification in the deamination reaction.
[D6]DMSO): δ ϭ 1.92 (s, 6 H), 2.27 (s, 3 H), 3.80 (s, 3 H), 6.06 (s,
1
Yield: 93% (1.89 g); brown oil. H NMR (400 MHz, [D6]DMSO): 1 H), 7.14 (t, J ϭ 7.8 Hz, 1 H), 7.22 (t, J ϭ 8.3 Hz, 1 H) 7.48 (d,
δ ϭ 1.08 (t, J ϭ 7.5 Hz, 3 H), 2.14 (s, 6 H), 2.47Ϫ2.52 (m, 1 H), J ϭ 8.3 Hz, 1 H), 7.55 (d, J ϭ 7.8 Hz, 1 H), 7.65 (s, 1 H) ppm. 13
2.66 (quint, J ϭ 7.5 Hz, 1 H), 4.11Ϫ4.13 (m, 2 H), 4.16Ϫ4.18 (m, NMR (100 MHz, [D6]DMSO): δ ϭ 15.2, 32.7, 37.4, 76.4, 100.7,
C
2 H), 6.28 (s, 1 H), 6.34 (s, 1 H), 6.58 (s, 1 H), 9.55 (br. s, 1 H)
110.4, 117.6, 118.5, 120.0, 122.0, 128.3, 128.8, 134.9, 136.7 ppm.
ppm. 13C NMR (100 MHz, [D6]DMSO): δ ϭ 14.7, 23.6, 37.7, 63.7, MS (EI): m/z (%) ϭ 322.2 (15) [Mϩ]. C15H18N2S3: calcd. C 55.86,
64.3, 76.7, 103.8, 111.9, 112.6, 117.7, 136.4, 140.7, 143.0, H 5.63; found C 55.51, H 5.55.
149.6 ppm. MS (MALDI-TOF): m/z ϭ 356.50 [Mϩ].
1
36: Yield: 95% (1.45 g); red oil. H NMR (400 MHz, [D6]DMSO):
Compounds 28Ϫ38 were prepared in the above manner.
δ ϭ 2.01 (s, 6 H), 2.20 (s, 3 H), 3.83 (s, 3 H), 6.13 (s, 1 H), 7.03 (d,
J ϭ 5.8 Hz, 1 H), 7.63 (d, J ϭ 5.8 Hz, 1 H) ppm. 13C NMR
(100 MHz, [D6]DMSO): δ ϭ 15.2, 37.3, 58.6, 58.7, 76.8, 105.9,
116.1, 116.6, 129.3, 131.5, 159.9 ppm. MS (EI): m/z (%) ϭ 305.1
(45) [Mϩ].
28: Yield: 98% (1.17 g); wine-red oil. 1H NMR (400 MHz,
[D6]DMSO): δ ϭ 1.09 (t, J ϭ 7.3 Hz, 3 H), 2.12 (s, 6 H), 2.45Ϫ2.55
(m, 1 H), 2.65Ϫ2.74 (quint, J ϭ 7.3 Hz, 1 H), 5.92 (s, 2 H), 6.24
(s, 1 H), 6.48 (s, 1 H), 6.65 (s, 1 H) ppm. 13C NMR (100 MHz,
[D6]DMSO): δ ϭ 14.6, 14.7, 23.5, 37.6, 76.6, 97.7, 97.8, 101.1,
37: Yield: 93% (1.02 g); dark orange oil. 1H NMR (400 MHz,
110.0, 113.3, 139.8, 140.1, 147.6, 151.1 ppm. MS (MALDI-TOF): [D6]DMSO): δ ϭ 0.85 (m, 3 H), 1.21Ϫ1.31 (m, 14 H), 1.45Ϫ1.54
m/z ϭ 342.47 [Mϩ].
(m, 2 H), 2.51Ϫ2.57 (m, 1 H), 2.67Ϫ2.76 (m, 1 H), 3.82 (s, 3 H),
6.16 (s, 1 H), 7.03 (d, J ϭ 5.8 Hz, 1 H), 7.63 (d, J ϭ 5.8 Hz, 1 H)
ppm. 13C NMR (100 MHz, [D6]DMSO): δ ϭ 13.9, 22.1, 28.5, 28.6,
28.7, 28.8, 28.9, 29.4, 29.7, 31.2, 37.4, 58.6, 76.7, 105.8, 115.9,
116.6, 129.2, 136.5, 159.9 ppm. MS (MALDI-TOF): m/z ϭ 430.62
[Mϩ]. C20H33NOS4: calcd. C 55.64, H 7.70; found C 55.82, H 7.84.
29: Yield: 95% (1.10 g) wine-red oil. 1H NMR (400 MHz,
[D6]DMSO): δ ϭ 2.11 (s, 6 H), 2.14 (s, 3 H), 5.92 (s, 2 H), 6.23 (s,
1 H), 6.47 (s, 1 H), 6.64 (s, 1 H), 9.70 (br. s, 1 H) ppm. 13C NMR
(100 MHz, [D6]DMSO): δ ϭ 15.3, 37.7, 76.6, 76.7, 97.7, 101.1,
110.0, 114.1, 133.3, 140.1, 147.5, 151.1 ppm. MS (MALDI-TOF):
m/z ϭ 329.18 [Mϩ].
38: Yield: 89% (0.73 g); dark orange oil. 1H NMR (500 MHz,
[D6]DMSO): δ ϭ 2.19 (s, 12 H), 2.24 (s, 6 H), 3.97 (s, 6 H), (s, 2
H) ppm. 13C NMR (124 MHz, [D6]DMSO): δ ϭ 15.6 (2 C), 38.2
(4 C), 61.0 (2 C), 99.6 (2 C), 115.0 (2 C), 117.2 (2 C), 133.7 (2 C),
151.0 (2C) ppm. MS (MALDI-TOF): m/z ϭ 525.63 [Mϩ].
30: Yield: Quantitative (0.28 g); orange oil. 1H NMR (400 MHz,
[D6]DMSO): δ ϭ 2.14 (s, 6 H), 2.26 (s, 3 H), 3.74 (s, 3 H), 5.88 (s,
1 H), 6.83 (dd, J ϭ 8.8 Hz, 1 H, 2.8 Hz), 6.88 (d, J ϭ 8.8 Hz, 1
H), 6.97 (d, J ϭ 2.8 Hz, 1 H) ppm. 13C NMR (100 MHz,
[D6]DMSO): δ ϭ 15.5, 18.4, 38.1, 55.9, 58.5, 114.0, 116.0, 117.6, Deamination of 28, 33, 35 and 36 with HPF6 to Give the Dithiolium
118.6, 118.7, 132.9, 150.3, 153.3 ppm. MS (EI): m/z (%) ϭ 315.2
Salts 39؊42
(2) [Mϩ], 270.1 (100).
Preparation of 39: 33 (1.9 mmol) was added in portions to ice-cold
concd. H2SO4 (15 mL) The mixture was stirred in an ice bath for
30 minutes and then poured onto 100 mL crushed ice containing
31: Yield: 79% (0.78 g); orange crystals. 1H NMR (400 MHz,
CDCl3): δ ϭ 1.91 (s, 6 H), 1.92 (s, 6 H), 2.36 (s, 3 H), 2.37 (s, 3
Eur. J. Org. Chem. 2004, 1455Ϫ1463
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1461

J. Hellberg, E. Dahlstedt, A. Woldegiorgis
FULL PAPER
60% aqueous HPF6 (1 mL). The orange precipitate formed was fil-
The bromide salt 47 (61 mmol) was dissolved in EtOH (150 mL),
tered and washed with cold H2O. The product was dissolved in and the flask put in an ice bath. NaBH4 (305 mmol) was added in
Et2O (or CH2Cl2) and dried with MgSO4, filtered and concentrated
to yield 39, which was used immediately in the TTF-forming reac-
tion. Yield: 60% (0.29 g); orange crystals. 1H NMR (400 MHz,
portions over 1 h, and the mixture stirred for a further 30 minutes
before it was quenched with 10% aqueous NH4Cl. This mixture
was extracted with CH2Cl2 and the organic phase washed with
CDCl3): δ ϭ 2.89 (s, 3 H), 3.93 (s, 3 H), 4.03 (s, 3 H), 7.18 (d, J ϭ water and dried with MgSO4. Evaporation gave the amino com-
2.5 Hz, 1 H), 7.31 (dd, J ϭ 9.1, 2.5 Hz, 1 H), 7.36 (d, J ϭ 9.1 Hz, pound as an oil. Yield: 77% (14.02 g); brown oil. 1H NMR
1 H) 7.99 (d, J ϭ 9.1 Hz, 1 H), 8.26 (d, J ϭ 9.1 Hz, 1 H), 10.76 (s,
1 H ppm.
(400 MHz, CDCl3): δ ϭ 0.91 (t, J ϭ 7.55 Hz, 3 H), 2.18 (s, 6 H),
2.16Ϫ2.25 (m, 1 H), 2.38Ϫ2.48 (m, 1 H), 3.87 (q, J ϭ 12.2 Hz, 2
H), 5.92 (s, 1 H), 7.16Ϫ7.29 (m, 5 H) ppm. 13C NMR (100 MHz,
CDCl3): δ ϭ 14.5, 23.7, 40.2 (2 C), 77.2, 114.0, 127.1, 128.3 (2 C),
128.9 (2 C), 137.8, 140.5.
Compounds 40Ϫ42 were prepared in the above manner.
40 (from 35): Yield: 71% (0.30 g); brown crystals.
The amino compound (46 mmol) was added to ice-cooled concd.
H2SO4 (150 mL) over 15 minutes. The resulting mixture was stirred
for another 40 minutes before it was slowly added to a slurry of
crushed ice (500 mL) and HPF6 (30 mL). The precipitate that
formed was filtered and washed with cold H2O, dissolved in
CH2Cl2 and reprecipitated with 1 volume of Et2O. After filtration
and washing with Et2O, the dithiolium salt was dried in a desic-
cator overnight. Yield: 87% (15.94 g); orange crystals. 1H NMR
(400 MHz, CDCl3): δ ϭ 1.40 (t, J ϭ 7.6 Hz, 3 H), δ ϭ 3.09 (q, J ϭ
7.6 Hz, 2 H), 4.23 (s, 2 H), 7.22Ϫ7.25 (m, 2 H), 7.33Ϫ7.37 (m, 3
H), 10.97 (s, 1 H) ppm.
41 (from 28): Yield: 89% (1.35 g); 1H NMR (400 MHz, CDCl3):
δ ϭ 1.55 (t, J ϭ 7.6 Hz, 3 H), 3.19 (q, J ϭ 7.6 Hz, 2 H), 6.03 (s, 2
H), 6.69 (s, 1 H), 6.93 (s, 1 H), 10.72 (s, 1 H) ppm.
42 (from 36): Yield: 70% (0.48 g); dark purple crystals.
Preparation of TTF 43: 39 (1.1 mmol) was dissolved (or suspended)
in dry CH3CN (10 mL) and the mixture purged with N2. Et3N
(1.1 equiv.) was added dropwise, resulting in the formation of a
precipitate and the clearance of the solution. After approx 1 h the
precipitate was filtered, washed with CH3CN and dried, yielding
crude 43 (268 mg, 75%) as orange crystals. After purification by
chromatography on a silica gel column (CH2Cl2) and recrystalliza-
tion from CH2Cl2/heptane, pure 43 was obtained. Yield: 35%
The dithiolium salt (39 mmol) was dissolved in 200 mL CH3CN;
the flask was then sealed and purged with N2. Et3N (46 mmol) was
added dropwise; an orange precipitate formed. The mixture was
stirred for 10 minutes, and then the precipitate was filtered, washed
with CH3CN and EtOH and dried to give TTF 47. Yield: 89%
(8.67 g); orange crystals. Rf (hexane/CH2Cl2) ϭ 0.23. 1H NMR
(400 MHz, CDCl3): δ ϭ 0.73Ϫ0.79 (m, 6 H), 2.15Ϫ2.23 (m, 4 H),
3.96Ϫ3.99 (m, 4 H), 7.23Ϫ7.36 (m, 10 H) ppm. MS (MALDI-
TOF): m/z (%) ϭ 504.03 (100) [Mϩ]. C24H24S6: calcd. C 57.10, H
4.79; found C 57.02, H 4.83.
(125 mg); pale orange crystals. M.p.
Ͼ
210 °C. 1H NMR
(400 MHz, CDCl3): δ ϭ 2.21 (s, 6 H), 3.86 (s, 6 H), 3.92 (s, 6 H),
7.28 (dd, J ϭ 9.3, 2.8 Hz, 2 H), 7.37 (d, J ϭ 2.8 Hz, 2 H), 7.47 (d,
J ϭ 9.1 Hz, 2 H) 7.98 (d, J ϭ 9.1 Hz, 2 H), 8.23 (d, J ϭ 9.3 Hz, 2
H) ppm. MS (EI): m/z (%) ϭ 668.17 (100) [Mϩ]. C32H28O4S6: calcd.
C 57.45, H 4.22; found C 56.98, H 4.30.
44: This was prepared (from 40) in the same manner as for 43. The
crude product (68 mg, 36%) was collected as red crystals. After
purification by chromatography on a silica gel column (CH2Cl2)
followed by recrystallization from CH2Cl2/heptane, pure 44 (11 mg)
was obtained. Yield: 16% (31 mg); pale orange crystals. M.p.
142.3Ϫ144.2 °C. An additional 20 mg of product was obtained
from chromatography of the mother liquor. A mixture of cis and
trans isomers were obtained, which were not separable by chroma-
tography. 1H NMR (400 MHz, CDCl3): δ ϭ 2.20/2.24 (s, 6 H),
3.81/3.79 (s, 6 H), 7.13Ϫ7.17 (m, 2 H), 7.22Ϫ7.27 (m, 2 H),
7.49Ϫ7.53 (m, 4 H), 7.72/7.70 (s, 2 H) ppm. MS (EI): m/z (%) ϭ
554.16 (100) [Mϩ]. C26H22N2S6: calcd. C 56.28, H 4.00; found C
56.10, H 4.14.
Acknowledgments
Financial support from The Swedish Research Council is gratefully
acknowledged. Special thanks to Dr. Mats Jonsson for assistance
with the cyclic voltammetry experiments.
[1] [1a]
Synth. Met., volumes 133Ϫ134, pages 1Ϫ730, 2003, Pro-
ceedings of the Yamada Conference LVI, the Fourth Inter-
national.
[1b]
Synth. Met., volumes 135Ϫ136, pages 1Ϫ858,
2003, Proceedings of the International Conference on Science
and Technology of Synth. Met., Shanghai, China.
M. Narita, C. U. Pittman, Synthesis 1976, 489Ϫ514.
Khodorkovsky, O. Neilands, Latv. Zin. Akad. Vest. 1982, 2,
45: This was prepared (from 42) in the same manner as for 43. MS
(EI): m/z (%) ϭ 520.15 (100) [Mϩ]. The product could not be ob-
tained analytically pure due to decomposition during purification
by column chromatography.
[2] [2a]
[2b]
W.
[2c]
[2d]
131Ϫ158.
A. Krief, Tetrahedron 1986, 42, 1209Ϫ1252.
G. Schukat, A. M. Richter, E. Fanghänel, Sulfur Reports 1987,
7, 155Ϫ240. [2e] G. Schukat, E. Fanghänel, Sulfur Reports 1993,
[2f]
Preparation of TTF 47 from Mesoion 2a: The mesoion 2a (0.1 mol)
was refluxed in acetone (500 mL) with benzyl bromide (0.1 mol)
until the yellow colour faded. After cooling to room temperature,
the bromide salt precipitated. This was filtered and washed with
acetone and Et2O (to remove traces of starting material), to yield
47. Yield: 96% (36 g); white crystals. 1H NMR (400 MHz, CDCl3):
δ ϭ 0.76 (t, J ϭ 7.6 Hz, 3 H), 2.24 (q, J ϭ 7.6 Hz, 2 H), 3.52 (s, 3
H), 3.55 (s, 3 H), 3.80 (s, 2 H), 7.02Ϫ7.09 (m, 3 H), 7.10Ϫ7.15 (m,
2 H) ppm. 13C NMR (100 MHz, CDCl3): δ ϭ 14.1, 22.9, 41.3, 47.6,
47.9, 123.6, 127.5, 128.5, 128.6, 135.1, 149.0, 184.6 ppm. MS (EI):
m/z (%) ϭ 296.1 (100) [Mϩ]. C14H18BrNS3: calcd. C 44.67, H 4.82;
found C 44.64, H 4.87.
14, 245Ϫ390.
G. Schukat, E. Fanghänel, Sulfur Reports
1996, 18, 1Ϫ294. [2g] G. Schukat, E. Fanghänel, Sulfur Reports
2003, 24, 1Ϫ190.
[3] [3a]
A. Souizi, A. Robert, C. R. Acad. Sc. Paris 2 1982, 295(5),
[3b]
571Ϫ573.
A. Souizi, A. Robert, Tetrahedron 1983, 40,
[3c]
1817Ϫ1822.
1059Ϫ1061.
A. Souizi, A. Robert, Synthesis 1982,
[4] [4a]
M. Jørgensen, K. Lerstrup, K. Bechgaard, Synth. Met.
[4b]
1991, 41Ϫ43, 2561Ϫ2564.
M. Jørgensen, K. A. Lerstrup,
[4c]
K. Bechgaard, J. Org. Chem. 1991, 56, 5684Ϫ5688.
F. Ber-
tho, A. Robert, P. Batail, P. Robin, Tetrahedron 1990, 46,
433Ϫ444. [4d] R. P. Parg, J. D. Kilburn, M. C. Petty, C. Pearson,
[4e]
T. G. Ryan, Synthesis 1994, 613Ϫ618.
F. Bertho-Thoraval,
1462
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org Eur. J. Org. Chem. 2004, 1455Ϫ1463

Umpolung of the 5-Alkyl-2-dimethylamino-1,3-dithiolium-4-thiolate Mesoion
A. Robert, A. Souizi, K. Boubekeur, P. Batail, J. Chem. Soc.,
FULL PAPER
2.42 (s, 6 H), 3.52 (s, 3 H), 3.53 (s, 3 H) ppm. MS (EI): m/z
[4f]
Chem. Commun. 1991, 843Ϫ845.
M. Jørgensen, K.
(%) ϭ 445.72 (20) [Mϩ], 242.06 (100).
[10]
[11]
1
Bechgaard, J. Org. Chem. 1994, 59, 5877Ϫ5882. [4g] K. Boubek-
eur, C. Lenoir, P. Batail, R. Carlier, A. Tallec, M.-P. Le Paillard,
Confirmed by H NMR analysis.
Ϫ
Ϫ
We found that the use of counterion PF6 is superior to BF4
D. Lorcy, A. Robert, Angew. Chem. Int. Ed. Engl. 1994, 33,
for the deamination reaction.
[4h]
[12]
1379Ϫ1381.
D. Lorcy, M.-P. Le Paillard, A. Robert, Tetra-
The reaction of 41 with triethylamine yielded a mixture of
products according to the NMR spectrum, which could not
be separated by chromatography. Direct inlet MS (EI) shows
predominant peaks at m/z (%) ϭ 298 (100), 181 (85), 434 (35)
and 254 (40) for both the crude material and the products aris-
ing from chromatography. There is a small signal (1%) at m/z ϭ
596 that corresponds to the corresponding TTF Mϩ ion. How-
ever, if one assumes that a mixture of oligomeric products and
a dimer 46 has been formed, the signal at m/z ϭ 596 would be
the molecular ion of the dimer, that at m/z ϭ 434 would be a
sesamol-1,3-dithiol-sesamol fragment and the mother ion
(m/z ϭ 298) would be a sesamol-1,3-dithiol fragment. This
could explain the behaviour apparent from the chromatogra-
phy, NMR spectra and mass spectra.
hedron Lett. 1993, 34, 5289Ϫ5292. [4i] M-P Le Paillard, A. Rob-
ert, Bull. Soc. Chim. Fr. 1992, 129, 205Ϫ208. [4j] M. Fourmigue,
´
I. Johannsen, K. Boubekeur, C. Nelson, P. Batail, J. Am. Chem.
Soc. 1993, 115, 3752Ϫ3759. [4k] K. Bechgaard, K. Lerstrup, M.
Jørgensen, I. Johannsen, J. Christensen, J. Larsen, Mol. Cryst.
[4l]
Liq. Cryst. 1990, 181, 161Ϫ169.
E. Dahlstedt, J. Hellberg,
Synth. Met. 2001, 119, 181Ϫ182. [4m] E. Dahlstedt, J. Hellberg,
J. Mater. Chem., in press.
[5] [5a]
`
M. Bssaibis, A. Robert, P. Lemagueres, L. Ouahab, R. Carl-
ier, A. Tallec, J. Chem. Soc., Chem. Commun. 1993, 601Ϫ602.
[5b] N. Bellec, D. Lorcy, A. Robert, Synthesis 1998, 1442Ϫ1446.
[5c]
M. Bssaibis, A. Robert, A. A. Souizi, J. Chem. Soc., Perkin
Trans. 1 1994, 1469Ϫ1472.
[6]
H. Gotthardt, M. Oppermann, Tetrahedron Lett. 1985, 26,
1627Ϫ1630.
[7] [7a]
P. Hascoat, D. Lorcy, A. Robert, K. Boubekeur, P. Batail,
R. Carlier, A. Tallec, J. Chem. Soc., Chem. Commun. 1995,
1229Ϫ1230. [7b] D. Lorcy, A. Robert, R. Carlier, A. Tallec, Bull.
Soc. Chim. Fr. 1994, 131, 774Ϫ778. [7c] G. Morel, E. Marchand,
S. Sinbandhit, R. Carlier, Eur. J. Org. Chem. 2001, 655Ϫ662.
The actual electrophile could have a structure different from 3,
although we believe this is less probable. In this redox reaction
we believe that sulfuryl chloride is converted to the chlorides
and sulfur dioxide, which is lost by evaporation during the re-
action.
[8]
[9]
1
Analysis of compound 26: H NMR (400 MHz, CDCl3): δ ϭ
Received October 23, 2003
Eur. J. Org. Chem. 2004, 1455Ϫ1463
www.eurjoc.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1463