Selective Metalation of 1,3-Dithiole-2-thiones: An Effective Preparation of New Symmetrically and Nonsymmetrically Tetraarylated Tetrathiafulvalenes

Article abstract of DOI:10.1055/s-0035-1560728

We report an efficient preparation of fully functionalized tetrathiafulvalene derivatives (TTF) with an extended π-system via a selective magnesiation of 1,3-dithiole-2-thiones (DTT) using 2,2,6,6-tetramethylpiperidin-1-ylmagnesium chloride-lithium chloride (TMPMgCl·LiCl); subsequent reaction with various electrophiles, such as halides, acid chlorides, allyl bromides, and aryl iodides, smoothly led to new mono- and difunctionalized 1,3-dithiole-2-thione derivatives. A triethyl phosphite mediated cross-coupling of the disubstituted 1,3-dithiole-2-thione derivatives with their oxygen analogues gave access to new symmetrically and nonsymmetrically tetraarylated tetrathiafulvalenes of interest as organic materials.

Full text of DOI:10.1055/s-0035-1560728

SYNTHESIS
0
0
3
9
-
7
8
8
1
1
4
3
7
-
2
1
0
X
© Georg Thieme Verlag Stuttgart · New York
2016, 48, 103–114
paper
103
J. Nafe, P. Knochel
Paper
Synthesis
Selective Metalation of 1,3-Dithiole-2-thiones: An Effective Prepa-
ration of New Symmetrically and Nonsymmetrically Tetraarylated
Tetrathiafulvalenes
1) TMPMgCl⋅LiCl
1) TMPMgCl⋅LiCl
E1
E1
Julia Nafe
S
S
S
THF, –78 °C, 0.5 h
THF, –78 °C, 0.5 h
Paul Knochel*
S
S
S
2) E1-X
2) E2-X
S
S
E2
S
Department of Chemistry, Ludwig-Maximilians-Universität,
Butenandtstrasse 5-13, 81377 München, Germany
paul.knochel@cup.uni-muenchen.de
9 examples
14 examples
50–94% yield
70–96% yield
E2
S
S
O
E1
E1
E2
S
S
S
S
S
E2
4 examples
53–67% yield
X
P(OEt)3, 110 °C, 1.5–3 h
S
E1
E1
E2
X = S, O
Received: 17.09.2015
Accepted after revision: 22.09.2015
Published online: 21.10.2015
tion. This is the case for 1,3-dithiole-2-thione (2; DTT)
which produces intermediates of type 3 after metalation. In
the next step, the reaction of 3 with an electrophile (E-X)
affords substituted heterocycles of type 4. However, the
presence of a leaving group in β-position to the carbon–
metal bond may lead to ring fragmentation and, therefore,
to the decomposition of intermediate 3 (Scheme 1). This
behavior can be expected when the carbon–metal bond is
very ionic (Met = Li).8
DOI: 10.1055/s-0035-1560728; Art ID: ss-2015-t0544-op
Abstract We report an efficient preparation of fully functionalized
tetrathiafulvalene derivatives (TTF) with an extended π-system via a se-
lective magnesiation of 1,3-dithiole-2-thiones (DTT) using 2,2,6,6-te-
tramethylpiperidin-1-ylmagnesium chloride–lithium chloride (TMPMg-
Cl·LiCl); subsequent reaction with various electrophiles, such as halides,
acid chlorides, allyl bromides, and aryl iodides, smoothly led to new
mono- and difunctionalized 1,3-dithiole-2-thione derivatives. A triethyl
phosphite mediated cross-coupling of the disubstituted 1,3-dithiole-2-
thione derivatives with their oxygen analogues gave access to new sym-
metrically and nonsymmetrically tetraarylated tetrathiafulvalenes of in-
terest as organic materials.
Met
E
S
S
S
E-X
R-Met
– RH
S
S
S
S
S
S
2
3
4
Key words metalation, organomagnesium reagents, palladium,
cross-coupling, organic materials
T > 0 °C Met = MgX, Li
decomposition
via fragmentation
The functionalization of heterocycles is an important
synthetic task since many of these ring systems have inter-
esting biological or electronic properties.1 The directed
metalation of heterocycles is one of the most general meth-
ods for achieving broad heterocyclic functionalization.2 Re-
cently, we have developed a range of 2,2,6,6-tetrameth-
ylpiperidin-1-yl (TMP) bases of magnesium and zinc, such
as TMPMgCl·LiCl (1),3 TMPZnCl·LiCl,4 and (TMP)2Zn·2MgCl2·
2LiCl.5 These bases metalate a range of polyfunctionalized
aromatics and heterocycles under mild conditions. The
large steric hindrance of the 2,2,6,6-tetramethylpiperidin-
1-yl moiety ensures a monomeric structure for this base6
and the extra equivalent of lithium chloride is responsible
for the high solubility of these bases in tetrahydrofuran (1.2
M). The metalation of sulfur-containing heterocycles can be
achieved with lithium bases.7 However, the presence of ad-
ditional sensitive functionalities or the nature of the S-het-
erocycle may lead to side reactions, such as ring fragmenta-
Scheme 1 Metalation of 1,3-dithiole-2-thione (2; DTT) leading to the
metalated intermediate of type 3 and quenching with an electrophile
(E-X)
Herein, we report a convenient sequential difunctional-
ization of 1,3-dithiole-2-thione (2) using 2,2,6,6-tetrameth-
ylpiperdin-1-ylmagnesium
chloride–lithium
chloride
(TMPMgCl·LiCl, 1).3 The quenching of the magnesiated 1,3-
dithiole-2-thione intermediate with a first electrophile (E1-
X) leads to monosubstituted heterocycles of type 4. A sec-
ond magnesiation can be achieved using the same base and
similar reaction conditions and quenching with a second
electrophile (E2-X) provides disubstituted 1,3-dithiole-2-
thione derivatives of type 5. To demonstrate the potential of
this methodology, the new disubstituted 1,3-dithiole-2-thi-
ones 5 were subjected to triethyl phosphite mediated cross-
coupling9 with their oxygen analogues 6 giving access to a
range of new fully functionalized tetrathiafulvalene (TTF)
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, 103–114

104
J. Nafe, P. Knochel
Paper
Synthesis
derivatives of type 7 that belong to an important class of or-
ganic materials10 due to their electrical and optical proper-
ties (Scheme 2).
Table 1 Preparation of Monofunctionalized 1,3-Dithiole-2-thione De-
rivatives of Type 4 by Magnesiation of 1,3-dithiole-2-thione (2) with
TMPMgCl·LiCl (1)
1) TMPMgCl⋅LiCl (1; 1.1 equiv)
E1
E1
E1
S
S
S
THF, –78 °C, 0.5 h
S
S
1) TMPMgCl⋅LiCl (1)
1) TMPMgCl⋅LiCl (1)
S
S
S
S
S
2) E1-X (1.2 equiv)
S
2) E1-X
2) E2-X
S
S
S
S
E2
2
4
4
5
2
E2
Yield (%)a
S
Entry Electrophile
Product
O
E1
E1
S
R
S
E1
E2
E2
S
E2
6
S
S
S
S
S
4a: R = I
4b: R = Br
P(OEt)3
S
S
S
E1
1
2
3
I2
79
84
75
7
5
(BrCl2C)2
Scheme 2 Preparation of mono- and disubstituted 1,3-dithiole-2-thi-
one derivatives of type 4 and 5 by metalation of 2 followed by a triethyl
phosphite mediated cross-coupling leading to fully functionalized
tetrathiafulvalene derivatives of type 7
MeSO2SMe
4c: R = SMe
O
O
Cl
S
S
Cl
4
5
62b,c
Cl
After extensive optimization, we found that TMPMgCl·
LiCl (1; 1.1 equiv, THF, –78 °C, 0.5 h) leads to complete mag-
nesiation of 1,3-dithiole-2-thione (2). Quenching of the
metalated species 3 with iodine or 1,2-dibromotetrachlo-
roethane produced the corresponding halogenated prod-
ucts 4a,b in 79–84% isolated yield (Table 1, entries 1 and 2).
Thiolation with S-methyl methanethiosulfonate furnished
the methyl thioether 4c in 75% yield (entry 3). Various car-
bon electrophiles reacted readily. Thus, the acylation with
3-chlorobenzoyl chloride, after domino-transmetalation11
with zinc chloride and copper(I) cyanide–di(lithium chlo-
ride) (CuCN·2LiCl),12 provides ketone 4d in 62% yield (entry
4). Copper-mediated allylation with ethyl (2-bromometh-
yl)acrylate13 led to the allylated 1,3-dithiole-2-thione 4e in
50% yield (entry 5). Magnesiated 1,3-dithiole-2-thione 2
undergoes a range of Negishi cross-coupling reactions14
with aryl iodides as the electrophile in the presence of
S
4d
EtO2C
S
EtO2C
S
50b,c
Br
S
4e
R
R
I
S
S
S
6
7
R = CO2Et
R = CN
4f: R = CO2Et
4g: R = CN
4h: R = Cl
84d
94d
67d
66d
79d
77d
70d
8
R = Cl
9
R = CF3
R = CH3
R = NO2
R = OMe
4i: R = CF3
4j: R = CH3
4k: R = NO2
4l: R = OMe
10
11
12
N-methylpyrrolidin-2-one
as
a
polar
co-solvent;
tetrakis(triphenylphosphine)palladium(0) (10 mol%) was
the best catalyst in a tetrahydrofuran–N-methylpyrrolidin-
2-one mixture (2:1) (25 °C, 1–18 h). Interestingly, electron-
withdrawing and electron-donating groups could be at-
tached to the electron-rich 1,3-dithiole-2-thione-core af-
fording the corresponding arylated 1,3-dithiole-2-thione
derivatives 4f–n in 60–94% yield (entries 6–14).
A second magnesiation was achieved by treating various
monosubstituted 1,3-dithiole-2-thiones of type 4 with
TMPMgCl·LiCl (1; 1.1 equiv, THF, –78 °C, 0.5 h). After
quenching the reaction with the same type of electrophile
as shown in Table 1, it was possible to prepare 4,5-disubsti-
tuted 1,3-dithiole-2-thiones 5a–i in 70–94% yield (Table 2).
Also in this case, the Negishi cross-couplings were best per-
formed with tetrakis(triphenylphosphine)palladium(0)
(10 mol%) as the catalyst in a mixture of tetrahydrofuran–
N-methylpyrrolidin-2-one (2:1).
S
S
R
S
R
I
13
14
R = NO2
R = OMe
4m: R = NO2
4n: R = OMe
60d
94d
a Isolated yield of analytically pure product.
b ZnCl2 solution was added.
c CuCN·2LiCl solution was added.
d Cross-coupling conditions: ZnCl2 transmetalation, 10 mol% Pd(PPh3)4,
THF–NMP (2:1).
Various 4,5-disubstituted 1,3-dithiole-2-thiones of type
5 could be converted into the corresponding oxygen ana-
logues of type 6 by treatment with mercury(II) acetate (3.0
equiv) in a mixture of chloroform and acetic acid (4:1)
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, 103–114

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J. Nafe, P. Knochel
Paper
Synthesis
Table 2 Preparation of Disubstituted 1,3-Dithiole-2-thione Derivatives
of Type 5 by Magnesiation of Monosubstituted 1,3-dithiole-2-thione
Derivatives of Type 4 with TMPMgCl·LiCl (1)
E1
E2
E1
E2
S
S
S
Hg(OAc)2 (3.0 equiv)
S
O
CHCl3–AcOH, 25 °C, 1–2 h
NC
S
6
E1
1) TMPMgCl⋅LiCl (1; 1.1 equiv)
5
E1
E2
S
S
THF, –78 °C, 0.5 h
S
Br
S
S
S
S
S
2) E2-X (1.2 equiv)
S
O
O
4
S
5
6a: 86%
6b: 75%
Entry Substrate Electrophile
Product
Yielda (%)
NC
Cl
F3C
Br
S
S
S
S
S
S
R
O
O
1
2
3
4b
4b
4b
(BrCl2C)2
I2
5a: R = Br
91
70
94
S
5b: R = I
6d: 91%
6c: 92%
Cl
F3C
TBDMSOTf
5c: R = TBDMS
Scheme 3 Preparation of oxygen analogues 6a–d
MeS
S
S
4
4c
MeSO2SMe
86
S
MeS
5d
spectively (53–67% yield; Scheme 4). These new fully func-
tionalized tetrathiafulvalene derivatives are of interest for
material science due to their extended π-system.
MeO
In summary, we have developed a novel synthesis al-
lowing the preparation of tailor-made fully substituted
tetrathiafulvalene derivatives via a selective functionaliza-
tion of the 1,3-dithiole-2-thione precursor. 1,3-Dithiole-2-
thione (2) can easily be magnesiated using TMPMgCl·LiCl
leading to new mono- and disubstituted 1,3-dithiole-2-thi-
one derivatives. Due to the gentle reaction conditions vari-
ous functional groups are tolerated. Subsequent triethyl
phosphite mediated cross-coupling with their oxygen ana-
logues leads to new symmetrically and nonsymmetrically
tetraarylated tetrathiafulvalene derivatives that are poten-
tially useful substrates for materials science.
S
5
4l
I2
96
S
S
I
5e
R
S
S
R
I
S
R
6
7
8
9
4g
4h
4i
R = CN
R = Cl
5f: R = CN
5g: R = Cl
5h: R = CF3
5i: R = Me
83b
93b
89b
89b
R = CF3
R = Me
All air- and moisture-sensitive reactions were carried out under an
argon atmosphere in flame-dried glassware. Syringes which were
used to transfer anhydrous solvents or reagents were purged with ar-
gon prior to use. THF was continuously refluxed and freshly distilled
from sodium benzophenone ketyl under N2 and stored over molecu-
lar sieves. Reactions were monitored by gas chromatography (GC and
GC-MS) or TLC. TLC was performed using silica gel (Merck 60, F-254)
covered aluminum plates and visualized by UV detection. Yields refer
to isolated yields of compounds estimated to be >95% pure as deter-
mined by 1H NMR (25 °C) and capillary GC. Purification by column
chromatography was performed using silica gel (0.040–0.063 mm,
230–400 mesh ASTM) from Merck. 2,2,6,6-Tetramethylpiperidine
(TMPH) was distilled prior to use. CuCN, ZnCl2, and LiCl were ob-
tained from Merck. 1,3-Dithiole-2-thione (2; DTT) was prepared ac-
cording to the literature.15 All reagents were obtained from commer-
cial sources.
4j
a Isolated yield of analytically pure product.
b Cross-coupling conditions: ZnCl2 transmetalation, 10 mol% Pd(PPh3)4, THF–
NMP (2:1).
(25 °C, 1–2 h).8f Thus, the monobromo-oxygen analogue 6a,
as well as the diarylated compounds 6b–d were obtained in
75–92% yield (Scheme 3).
Both symmetrical and nonsymmetrical tetrathiaful-
valenes 7 were prepared via a triethyl phosphite mediated
cross-coupling (110 °C, 1.5–3 h).9b In the first case, the
functionalized 1,3-dithiole-2-ones 6c and 6d furnished the
corresponding tetraarylated tetrathiafulvalene derivatives
7a and 7b (54–63% yield) after treatment with triethyl
phosphite. On the other hand, the nonsymmetrically sub-
stituted tetrathiafulvalene derivatives 7c and 7d were pre-
pared by cross-coupling of 5i with 6b and 5f with 6d, re-
IR spectra were recorded on a Perkin Elmer Spectrum BX-59343 spec-
trophotometer. Samples were measured neat (ATR, Smiths Detection
DuraSample IR II Diamond ATR). NMR spectra were recorded on
Bruker AXR 300, VXR 400 S and Bruker AMX 600 instruments. HRMS
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, 103–114

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J. Nafe, P. Knochel
Paper
Synthesis
R1
R1
R1
S
S
S
S
S
S
6
P(OEt)3
O
110 °C, 3 h
R1
R1
R1
7a: R1 = Cl; 54%
7b: R1 = CF3; 63%
R2
S
S
O
R1
R2
R1
R2
S
S
S
S
S
5
(6; 1.2 equiv)
S
S
P(OEt)3, 110 °C, 1.5–2 h
R1
R2
R1
7c: R1 = Me, R2 = CN; 67%
7d: R1 = CN, R2 = CF3; 53%
Scheme 4 Preparation of tetraarylated tetrathiafulvalene derivatives of type 7 by a triethyl phosphite mediated cross-coupling
and LR-MS were recorded on a Finnigan MAT 95Q instrument using
electron ionization (EI). Gas chromatography was performed with
machines of type Hewlett-Packard 6890 or 5890 series II, using a col-
umn of type HP 5 (Hewlett-Packard, 5% phenylmethylpolysiloxane;
length: 15 m, diameter: 0.25 mm; film thickness: 0.25 μm).
Magnesiation of 1,3-Dithiole-2-thione (2) with 2,2,6,6-Tetrameth-
ylpiperidin-1-ylmagnesium Chloride–Lithium Chloride (1); Gen-
eral Procedure 1 (GP1)
A dry and argon flushed Schlenk flask was charged with a solution of
DTT (2; 1.0 equiv) in anhyd THF (0.5 M). 1 M TMPMgCl·LiCl in THF (1;
1.1 equiv) was added dropwise at –78 °C and the mixture was stirred
at this temperature for 0.5 h. The completion of the reaction was
checked by GC analysis of reaction aliquots quenched with I2 in anhyd
THF.
Copper(I) Cyanide–Di(lithium chloride) (CuCN·2LiCl) Solution
A 1.0 M CuCN·2LiCl in THF solution was prepared by drying CuCN
(7.17 g, 80 mmol) and LiCl (6.77 g, 160 mmol) in a Schlenk flask un-
der high vacuum at 140 °C for 5 h. After cooling, anhyd THF (80 mL)
was added and stirring was continued until all salts were dissolved
(24 h).
Magnesiation of 4-Functionalized 1,3-Dithiole-2-thione Deriva-
tives 4 with 2,2,6,6-Tetramethylpiperidin-1-ylmagnesium Chlo-
ride–Lithium Chloride (1); General Procedure 2 (GP2)
Zinc Chloride Solution
A dry and argon flushed Schlenk flask was charged with a solution
the corresponding 4-functionalized DTT derivative 4 (1.0 equiv) in
anhyd THF (0.10–0.50 M). 1 M TMPMgCl·LiCl in THF (1; 1.1 equiv)
was added dropwise at –78 °C and the mixture was stirred at this
temperature for 0.5 h. The completion of the reaction was checked by
TLC analysis of reaction aliquots quenched with iodine in anhyd THF.
A 1.0 M ZnCl2 in THF solution was prepared by drying ZnCl2 (136.3 g,
100 mmol) in a Schlenk flask under vacuum at 140 °C for 5 h. After
cooling, anhyd THF (100 mL) was added and stirring was continued
until all salts were dissolved (12 h).
2,2,6,6-Tetramethylpiperidin-1-ylmagnesium Chloride–Lithium
Chloride (TMPMgCl·LiCl, 1)
1,3-Dithiol-2-one Derivatives 6; General Procedure 3 (GP3)
According to the literature procedure,8f the corresponding DTT deriv-
ative 5 (1.0 equiv) was dissolved in CHCl3 (0.05 M) and AcOH (0.16
M). Hg(OAc)2 (3.0 equiv) was added portionwise at 25 °C and the mix-
ture was stirred at this temperature for the indicated time. The com-
pletion of the reaction was checked by TLC analysis of reaction ali-
quots quenched with sat. aq NH4Cl solution.
In a dry and argon flushed Schlenk flask 2,2,6,6-tetramethylpiperi-
dine (14.8 g, 105 mmol) was added to 1.40 M i-PrMgCl·LiCl in THF
(71.4 mL, 100 mmol) at 25 °C and the mixture was stirred for 24 h at
25 °C. The freshly prepared TMPMgCl·LiCl was titrated prior to use at
0 °C with benzoic acid using 4-(phenylazo)diphenylamine as indica-
tor.
Tetrathiafulvalene Derivatives 7; General Procedure (GP4)
According to the literature procedure,9b the corresponding DTT deriv-
ative 5 (1.0 equiv) was dissolved in freshly distilled P(OEt)3 (0.1 M).
The corresponding oxygen analogue 6 (1.2 equiv) was added at 25 °C
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, 103–114

107
J. Nafe, P. Knochel
Paper
Synthesis
and the mixture was stirred at 110 °C for the indicated time. The
completion of the reaction was checked by TLC analysis of reaction al-
iquots quenched with sat. aq NH4Cl solution.
IR: 3058, 1191, 1056, 1044, 1028, 737 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 6.91 (s, 1 H), 2.51 (s, 3 H).
13C NMR (75 MHz, CDCl3): δ = 213.5, 138.5, 127.2, 19.8.
MS (70 eV, EI): m/z (%) = 182 (13), 180 (100) [M+], 104 (27), 103 (44),
89 (42), 76 (23), 57 (10), 45 (26).
4-Iodo-1,3-dithiole-2-thione (4a)16
According to GP1, DTT (2; 1.07 g, 8.0 mmol) was dissolved in anhyd
THF (16 mL). TMPMgCl·LiCl (1; 7.93 mL, 8.8 mmol, 1.11 M in THF)
was added dropwise at –78 °C and the mixture was stirred for 0.5 h.
The freshly prepared magnesium reagent was added to a solution of I2
(2.44 g, 9.6 mmol) in anhyd THF (20 mL) at –78 °C. The mixture was
stirred at this temperature for 1 h, it was then quenched with sat. aq
Na2S2O3 solution (50 mL) and extracted with Et2O (3 × 100 mL), and
the combined extracts were dried (anhyd Na2SO4). After filtration, the
solvents were evaporated in vacuo. The crude product was purified
by flash column chromatography (silica gel, isohexane–Et2O, 95:5)
yielding 4a (1.65 g, 79%) as a brownish solid; mp 106–109 °C.
HRMS (EI): m/z [M+] calcd for C4H4S4: 179.9196; found: 179.9193.
(3-Chlorophenyl)(2-thioxo-1,3-dithiol-4-yl)methanone (4d)
According to GP1, DTT (2; 67.1 mg, 0.5 mmol) was dissolved in anhyd
THF (1 mL). TMPMgCl·LiCl (1; 0.50 mL, 0.55 mmol, 1.11 M in THF)
was added dropwise at –78 °C and the mixture was stirred for 0.5 h. A
ZnCl2 solution (0.6 mL, 0.6 mmol, 1.0 M in THF) was added at –78 °C
and the mixture was stirred for 15 min. A CuCN·2LiCl solution
(0.6 mL, 0.6 mmol, 1.0 M in THF) was added at –78 °C and the mix-
ture was stirred at –40 °C for 15 min, before 3-chlorobenzoyl chloride
(105 mg, 0.08 mL, 0.6 mmol) was added. The mixture was stirred at
25 °C for 12 h, it was then quenched with aq NH4Cl/NH3 solution (8:1,
5 mL) and extracted with Et2O (3 × 10 mL), and the combined extracts
were dried (anhyd Na2SO4). After filtration, the solvents were evapo-
rated in vacuo. The crude product was purified by flash column chro-
matography (silica gel, isohexane–Et2O, 9:1) yielding 4d (84 mg, 62%)
as a brown oil.
IR: 3066, 1045, 1015, 885, 758, 645 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.21 (s, 1 H).
13C NMR (101 MHz, CDCl3): δ = 215.1, 133.8, 69.9.
MS (70 eV, EI): m/z (%) = 260 (62) [M+], 184 (13), 135 (11), 133 (100),
127 (22), 89 (26), 88 (11), 76 (45).
HRMS (EI): m/z [M+] calcd for C3HIS3: 259.8285; found: 259.8275.
IR: 3061, 1628, 1511, 1266, 1075, 727 cm–1
.
4-Bromo-1,3-dithiole-2-thione (4b)8f
1H NMR (300 MHz, CDCl3): δ = 7.80–7.72 (m, 2 H), 7.71–7.59 (m, 1 H),
7.49 (t, J = 7.9 Hz, 1 H), 7.11 (s, 1 H).
13C NMR (75 MHz, CDCl3): δ = 210.6, 182.5, 145.3, 139.6, 137.2, 135.3,
133.4, 130.3, 128.8, 126.9.
MS (70 eV, EI): m/z (%) = 274 (26), 272 (58) [M+], 196 (21), 141 (30),
According to GP1, DTT (2; 67.1 mg, 0.5 mmol) was dissolved in anhyd
THF (1 mL). TMPMgCl·LiCl (1; 0.50 mL, 0.55 mmol, 1.11 M in THF)
was added dropwise at –78 °C and the mixture was stirred for 0.5 h.
The freshly prepared magnesium reagent was added to a solution of
1,2-dibromotetrachloroethane (195 mg, 0.6 mmol) in anhyd THF (1
mL) at –78 °C. The mixture was allowed to warm up to 25 °C over
12 h, it was then quenched with sat. aq NH4Cl solution (5 mL) and ex-
tracted with Et2O (3 × 10 mL), and the combined extracts were dried
(anhyd Na2SO4). After filtration, the solvents were evaporated in vac-
uo. The crude product was purified by flash column chromatography
(silica gel, isohexane–Et2O, 95:5) yielding 4b (90 mg, 84%) as a yellow
solid; mp 62–64 °C.
IR: 3071, 1182, 1047, 1012, 904, 881, 765 cm–1
1H NMR (300 MHz, CDCl3): δ = 7.01 (s, 1 H).
13C NMR (75 MHz, CDCl3): δ = 211.8, 127.4, 106.2.
MS (70 eV, EI): m/z (%) = 214 (66), 212 (63) [M+], 57 (86), 57 (100), 55
139 (100), 111 (53), 75 (29).
HRMS (EI): m/z [M+] calcd for C10H5OClS3: 271.9191; found: 271.9190.
Ethyl 2-[(2-Thioxo-1,3-dithiol-4-yl)methyl]acrylate (4e)
According to GP1, DTT (2; 134 mg, 1.0 mmol) was dissolved in anhyd
THF (2 mL). TMPMgCl·LiCl (1; 0.99 mL, 1.1 mmol, 1.11 M in THF) was
added dropwise at –78 °C and the mixture was stirred for 0.5 h. A
ZnCl2 solution (1.2 mL, 1.2 mmol, 1.0 M in THF) was added at –78 °C
and the mixture was stirred for 15 min. A CuCN·2LiCl solution
(1.2 mL, 1.2 mmol, 1.0 M in THF) was added at –78 °C and the mix-
ture was stirred at –40 °C for 15 min, before ethyl 2-(bromometh-
yl)acrylate13 (214 mg, 0.17 mL, 1.2 mmol) was added. The mixture
was stirred at –40 °C for 4 h, it was then quenched with aq NH4Cl/NH3
solution (8:1, 5 mL) and extracted with Et2O (3 × 10 mL), and the
combined extracts were dried (anhyd Na2SO4). After filtration, the
solvents were evaporated in vacuo. The crude product was purified by
flash column chromatography (silica gel, isohexane–CH2Cl2, 1:1)
yielding 4e as a yellow oil (124 mg, 50%).
.
(58), 45 (50).
HRMS (EI): m/z [M+] calcd for C3HBrS3: 211.8424; found: 211.8429.
4-(Methylthio)-1,3-dithiole-2-thione (4c)17
According to GP1, DTT (2; 1.07 g, 8.0 mmol) was dissolved in anhyd
THF (16 mL). TMPMgCl·LiCl (1; 7.93 mL, 8.8 mmol, 1.11 M in THF)
was added dropwise at –78 °C and the mixture was stirred for 0.5 h.
The freshly prepared magnesium reagent was added to a solution of
S-methyl methanethiosulfonate (1.21 g, 0.99 mL, 9.6 mmol) in anhyd
THF (16 mL) at –78 °C. The mixture was stirred at this temperature for
1 h, it was then quenched with sat. aq NH4Cl solution (50 mL) and ex-
tracted with Et2O (3 × 100 mL), and the combined extracts were dried
(anhyd Na2SO4). After filtration, the solvents were evaporated in vac-
uo. The crude product was purified by flash column chromatography
(silica gel, isohexane–Et2O, 95:5) yielding 4c (1.08 g, 75%) as a brown-
ish solid; mp 73–75 °C.
IR: 2978, 1706, 1630, 1184, 1138, 1101, 1051, 1022 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 6.76 (s, 1 H), 6.36 (s, 1 H), 5.75 (s, 1 H),
4.24 (q, J = 7.2 Hz, 2 H), 3.60 (s, 2 H), 1.32 (t, J = 7.2 Hz, 3 H).
13C NMR (75 MHz, CDCl3): δ = 213.5, 165.6, 144.2, 136.5, 128.1, 124.3,
61.4, 33.5, 14.1.
MS (70 eV, EI): m/z (%) = 246 (100) [M+], 172 (23), 170 (23), 142 (41),
141 (40), 127 (19), 97 (15, 97 (76), 85 (22), 85 (12), 83 (17), 71 (31),
71 (14), 70 (13), 69 (24), 57 (50), 56 (14), 55 (31), 53 (19), 45 (15), 45
(37), 44 (33), 43 (33), 43 (15), 40 (28).
HRMS (EI): m/z [M+] calcd for C9H10O2S3: 245.9843; found: 245.9844.
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Ethyl 4-(2-Thioxo-1,3-dithiol-4-yl)benzoate (4f)
with sat. aq NH4Cl solution (5 mL) and extracted with EtOAc
(3 × 10 mL), and the combined extracts were dried (anhyd Na2SO4).
After filtration, the solvents were evaporated in vacuo. The crude
product was purified by flash column chromatography (silica gel, iso-
hexane–CH2Cl2, 2:1) yielding 4h (263 mg, 67%) as a yellow solid; mp
91–98 °C.
According to GP1, DTT (2; 134 mg, 1.0 mmol) was dissolved in anhyd
THF (2 mL). TMPMgCl·LiCl (1; 0.99 mL, 1.1 mmol, 1.11 M in THF) was
added dropwise at –78 °C and the mixture was stirred for 0.5 h. A
ZnCl2 solution (1.2 mL, 1.2 mmol, 1.0 M in THF) was added at –78 °C
and the mixture was stirred for 15 min. The freshly prepared zinc re-
agent was added to a solution of ethyl 4-iodobenzoate (221 mg, 0.13
mL, 0.8 mmol) and Pd(PPh3)4 (116 mg, 0.10 mmol) in anhyd NMP (1
mL) at 25 °C. The mixture was stirred at 25 °C for 1 h, it was then
quenched with sat. aq NH4Cl solution (5 mL) and extracted with
EtOAc (3 × 10 mL), and the combined extracts were dried (anhyd
Na2SO4). After filtration, the solvents were evaporated in vacuo. The
crude product was purified by flash column chromatography (silica
gel, isohexane–CH2Cl2, 1:1) yielding 4f (191 mg, 84%) as a yellow sol-
id; mp 136–138 °C.
IR: 3022, 1486, 1402, 1079, 1069, 818, 761 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 7.46–7.30 (m, 4 H), 7.11 (s, 1 H).
13C NMR (75 MHz, CDCl3): δ = 211.7, 144.7, 135.7, 129.6, 129.5, 127.7,
122.3.
MS (70 eV, EI): m/z (%) = 245 (49), 245 (14), 244 (100) [M+], 170 (40),
155 (13), 136 (16), 89 (31), 75 (10).
HRMS (EI): m/z [M+] calcd for C9H5ClS3: 243.9242; found: 243.9239.
IR: 1709, 1272, 1062, 1053, 754 cm–1
.
4-[4-(Trifluoromethyl)phenyl]-1,3-dithiole-2-thione (4i)
1H NMR (300 MHz, CDCl3): δ = 8.10 (d, J = 8.3 Hz, 2 H), 7.49 (d,
J = 8.3 Hz, 2 H), 7.28–7.22 (m, 1 H), 4.41 (q, J = 7.0 Hz, 2 H), 1.42 (t,
J = 7.1 Hz, 3 H).
13C NMR (75 MHz, CDCl3): δ = 211.6, 165.5, 144.8, 134.8, 131.3, 130.6,
126.3, 123.7, 61.4, 14.3.
MS (70 eV, EI): m/z (%) = 283 (13), 282 (100) [M+], 237 (10), 178 (18),
161 (56), 89 (20).
HRMS (EI): m/z [M+] calcd for C12H10O2S3: 281.9843; found: 281.9836.
According to GP1, DTT (2; 269 mg, 2.0 mmol) was dissolved in anhyd
THF (4 mL). TMPMgCl·LiCl (1; 1.98 mL, 2.2 mmol, 1.11 M in THF) was
added dropwise at –78 °C and the mixture was stirred for 0.5 h. A
ZnCl2 solution (2.4 mL, 2.4 mmol, 1.0 M in THF) was added at –78 °C
and the mixture was stirred for 15 min. The freshly prepared zinc re-
agent was added to a solution of 1-iodo-4-(trifluoromethyl)benzene
(435 mg, 1.6 mmol) and Pd(PPh3)4 (231 mg, 0.2 mmol) in anhyd NMP
(2 mL) at 25 °C. The mixture was stirred at 25 °C for 14 h, it was then
quenched with sat. aq NH4Cl solution (5 mL) and extracted with
EtOAc (3 × 10 mL), and the combined extracts were dried (anhyd
Na2SO4). After filtration, the solvents were evaporated in vacuo. The
crude product was purified by flash column chromatography (silica
gel, isohexane–CH2Cl2, 2:1) yielding 4i (287 mg, 66%) as a yellow sol-
id; mp 122–123 °C.
4-(2-Thioxo-1,3-dithiol-4-yl)benzonitrile (4g)18
According to GP1, DTT (2; 1.34 g, 10.0 mmol) was dissolved in anhyd
THF (20 mL). TMPMgCl·LiCl (1; 9.91 mL, 11.0 mmol, 1.11 M in THF)
was added dropwise at –78 °C and the mixture was stirred for 0.5 h. A
ZnCl2 solution (12.0 mL, 12.0 mmol, 1.0 M in THF) was added at
–78 °C and the mixture was stirred for 15 min. The freshly prepared
zinc reagent was added to a solution of 4-iodobenzonitrile (1.83 g,
8.0 mmol) and Pd(PPh3)4 (1.15 g, 1.0 mmol) in anhyd NMP (10 mL) at
25 °C. The mixture was stirred at 25 °C for 18 h, it was then quenched
with sat. aq NH4Cl solution (50 mL) and extracted with EtOAc
(3 × 100 mL), and the combined extracts were dried (anhyd Na2SO4).
After filtration, the solvents were evaporated in vacuo. The crude
product was purified by flash column chromatography (silica gel, iso-
hexane–CH2Cl2, 1:2) yielding 4g (1.77 g, 94%) as a yellow solid; mp
196–199 °C.
IR: 1321, 1124, 1112, 1053, 832 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.71 (d, J = 8.2 Hz, 2 H), 7.55 (d, J = 8.2
Hz, 2 H), 7.24 (s, 1 H).
13C NMR (101 MHz, CDCl3): δ = 211.4, 144.1, 134.2, 131.5 (q, J = 32.8
Hz), 126.8, 126.4 (q, J = 3.9 Hz), 123.9, 123.6 (q, J = 272.4 Hz).
MS (70 eV, EI): m/z (%) = 280 (10), 279 (13), 278 (100) [M+], 152 (15).
HRMS (EI): m/z [M+] calcd for C10H5F3S3: 277.9505; found: 277.9497.
4-(p-Tolyl)-1,3-dithiole-2-thione (4j)19
According to GP1, DTT (2; 269 mg, 2.0 mmol) was dissolved in anhyd
THF (4 mL). TMPMgCl·LiCl (1; 1.98 mL, 2.2 mmol, 1.11 M in THF) was
added dropwise at –78 °C and the mixture was stirred for 0.5 h. A Zn-
Cl2 solution (2.4 mL, 2.4 mmol, 1.0 M in THF) was added at –78 °C and
the mixture was stirred for 15 min. The freshly prepared zinc reagent
was added to a solution of 4-iodotoluene (349 mg, 1.6 mmol) and
Pd(PPh3)4 (231 mg, 0.2 mmol) in anhyd NMP (2 mL) at 25 °C. The mix-
ture was stirred at 25 °C for 3 h, it was then quenched with sat. aq
NH4Cl solution (5 mL) and extracted with EtOAc (3 × 10 mL), and the
combined extracts were dried (anhyd Na2SO4). After filtration, the
solvents were evaporated in vacuo. The crude product was purified
by flash column chromatography (silica gel, isohexane–CH2Cl2, 2:1)
yielding 4j (284 mg, 79%) as a yellow solid; mp 91–98 °C.
IR: 3037, 2228, 1412, 1063, 783 cm–1
1H NMR (300 MHz, CDCl3): δ = 7.74 (d, J = 8.3 Hz, 2 H), 7.53 (d, J = 8.3
Hz, 2 H), 7.28 (s, 1 H).
13C NMR (75 MHz, CDCl3): δ = 210.9, 143.4, 134.9, 133.2, 127.0, 124.8,
.
117.9, 113.2.
MS (70 eV, EI): m/z (%) = 237 (16), 236 (18) [M + H+], 160 (12), 159
(100), 146 (11), 115 (12), 76 (22).
HRMS (EI): m/z [M + H+] calcd for C10H6NS3: 235.9662; found:
235.9644.
4-(4-Chlorophenyl)-1,3-dithiole-2-thione (4h)19
IR: 1500, 1060, 1033, 762, 752 cm–1
1H NMR (300 MHz, CDCl3): δ = 7.36–7.28 (m, 2 H), 7.28–7.19 (m, 2 H),
7.06 (s, 1 H), 2.40 (s, 3 H).
13C NMR (75 MHz, CDCl3): δ = 212.4, 146.5, 140.0, 130.0, 128.3, 126.3,
.
According to GP1, DTT (2; 269 mg, 2.0 mmol) was dissolved in anhyd
THF (4 mL). TMPMgCl·LiCl (1; 1.98 mL, 2.2 mmol, 1.11 M in THF) was
added dropwise at –78 °C and the mixture was stirred for 0.5 h. A
ZnCl2 solution (2.4 mL, 2.4 mmol, 1.0 M in THF) was added at –78 °C
and the mixture was stirred for 15 min. The freshly prepared zinc re-
agent was added to a solution of 1-chloro-4-iodobenzene (382 mg,
1.6 mmol) and Pd(PPh3)4 (231 mg, 0.2 mmol) in anhyd NMP (2 mL) at
25 °C. The mixture was stirred at 25 °C for 3 h, it was then quenched
121.0, 21.3.
MS (70 eV, EI): m/z (%) = 225 (14), 224 (100) [M+], 178 (10), 149 (17),
148 (51), 147 (37), 115 (11), 91 (13), 69 (12), 43 (10).
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HRMS (EI): m/z [M+] calcd for C10H8S3: 223.9788; found: 223.9766.
at 25 °C. The mixture was stirred at 25 °C for 3 h, it was then
quenched with sat. aq NH4Cl solution (5 mL) and extracted with
EtOAc (3 × 10 mL), and the combined extracts were dried (anhyd
Na2SO4). After filtration, the solvents were evaporated in vacuo. The
crude product was purified by flash column chromatography (silica
gel, isohexane–CH2Cl2, 3:2) yielding 4m (122 mg, 60%) as a yellow sol-
id; mp 183–186 °C.
4-(4-Nitrophenyl)-1,3-dithiole-2-thione (4k)18
According to GP1, DTT (2; 1.34 g, 10.0 mmol) was dissolved in anhyd
THF (20 mL). TMPMgCl·LiCl (1; 9.91 mL, 11.0 mmol, 1.11 M in THF)
was added dropwise at –78 °C and the mixture was stirred for 0.5 h. A
ZnCl2 solution (12.0 mL, 12.0 mmol, 1.0 M in THF) was added at
–78 °C and the mixture was stirred for 15 min. The freshly prepared
zinc reagent was added to a solution of 1-iodo-4-nitrobenzene
(1.99 g, 8.0 mmol) and Pd(PPh3)4 (1.15 g, 1.0 mmol) in anhyd NMP (10
mL) at 25 °C. The mixture was stirred at 25 °C for 14 h, it was then
quenched with sat. aq NH4Cl solution (50 mL) and extracted with
EtOAc (3 × 100 mL), and the combined extracts were dried (anhyd
Na2SO4). After filtration, the solvents were evaporated in vacuo. The
crude product was purified by flash column chromatography (silica
gel, isohexane–CH2Cl2, 1:1) yielding 4k (1.57 g, 77%) as a brownish
solid; mp 209–211 °C.
IR: 1515, 1346, 1081, 735, 719, 680 cm–1
.
1H NMR (600 MHz, CDCl3): δ = 8.35–8.30 (m, 1 H), 8.28 (d, J = 8.2 Hz, 1
H), 7.73 (d, J = 8.0 Hz, 1 H), 7.69–7.62 (m, 1 H), 7.30 (s, 1 H).
13C NMR (151 MHz, CDCl3): δ = 210.8, 148.8, 142.7, 132.5, 132.1,
130.6, 124.5, 124.1, 121.2.
MS (70 eV, EI): m/z (%) = 257 (11), 255 (100) [M+], 225 (19), 166 (11),
149 (12), 89 (31), 76 (12), 43 (23).
HRMS (EI): m/z [M+] calcd for C9H5O2NS3: 254.9482; found: 254.9472.
IR: 2923, 1503, 1340, 1080, 1062, 742, 688 cm–1
.
4-(3-Methoxyphenyl)-1,3-dithiole-2-thione (4n)
1H NMR (600 MHz, CDCl3): δ = 8.32 (d, J = 8.8 Hz, 2 H), 7.60 (d, J = 8.8
Hz, 2 H), 7.33 (s, 1 H).
13C NMR (151 MHz, CDCl3): δ = 210.7, 148.0, 142.9, 136.6, 127.2,
125.4, 124.8.
MS (70 eV, EI): m/z (%) = 257 (15), 256 (13), 255 (100) [M+], 149 (24),
133 (19), 121 (12), 89 (53), 63 (15).
HRMS (EI): m/z [M+] calcd for C9H5O2NS3: 254.9482; found: 254.9479.
According to GP1, DTT (2; 134 mg, 1.0 mmol) was dissolved in anhyd
THF (2 mL). TMPMgCl·LiCl (1; 0.99 mL, 1.1 mmol, 1.11 M in THF) was
added dropwise at –78 °C and the mixture was stirred for 0.5 h. A
ZnCl2 solution (1.2 mL, 1.2 mmol, 1.0 M in THF) was added at –78 °C
and the mixture was stirred for 15 min. The freshly prepared zinc re-
agent was added to a solution of 3-iodoanisole (187 mg, 0.8 mmol)
and Pd(PPh3)4 (116 mg, 0.10 mmol) in anhyd NMP (1 mL) at 25 °C. The
mixture was stirred at 25 °C for 18 h, it was then quenched with sat.
aq NH4Cl solution (5 mL) and extracted with EtOAc (3 × 10 mL), and
the combined extracts were dried (anhyd Na2SO4). After filtration, the
solvents were evaporated in vacuo. The crude product was purified
by flash column chromatography (silica gel, isohexane–CH2Cl2, 3:1)
yielding 4n (181 mg, 94%) as a yellow solid; mp 94–98 °C.
4-(4-Methoxyphenyl)-1,3-dithiole-2-thione (4l)19
According to GP1, DTT (2; 1.34 g, 10.0 mmol) was dissolved in anhyd
THF (20 mL). TMPMgCl·LiCl (1; 9.91 mL, 11.0 mmol, 1.11 M in THF)
was added dropwise at –78 °C and the mixture was stirred for 0.5 h. A
ZnCl2 solution (12.0 mL, 12.0 mmol, 1.0 M in THF) was added at
–78 °C and the mixture was stirred for 15 min. The freshly prepared
zinc reagent was added to a solution of 4-iodoanisole (1.87 g,
8.0 mmol) and Pd(PPh3)4 (1.15 g, 1.0 mmol) in anhyd NMP (10 mL) at
25 °C. The mixture was stirred at 25 °C for 14 h, it was then quenched
with sat. aq NH4Cl solution (50 mL) and extracted with EtOAc
(3 × 100 mL), and the combined extracts were dried (anhyd Na2SO4).
After filtration, the solvents were evaporated in vacuo. The crude
product was purified by flash column chromatography (silica gel, iso-
hexane–CH2Cl2, 2:1) yielding 4l (1.34 g, 70%) as a yellow solid; mp
104–107 °C.
IR: 1575, 1165, 1054, 1034, 853, 757 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 7.34 (t, J = 7.9 Hz, 1 H), 7.14–7.07 (m, 1
H), 7.04–6.89 (m, 3 H), 3.85 (s, 3 H).
13C NMR (75 MHz, CDCl3): δ = 212.1, 160.1, 146.0, 132.1, 130.4, 122.1,
118.9, 115.0, 112.3, 55.4.
MS (70 eV, EI): m/z (%) = 242 (14), 241 (14), 240 (100) [M+], 164 (52),
135 (10), 134 (16), 121 (21), 77 (11).
HRMS (EI): m/z [M+] calcd for C10H8OS3: 239.9737; found: 239.9735.
4,5-Dibromo-1,3-dithiole-2-thione (5a)8f
IR: 1602, 1498, 1260, 1026, 770 cm–1
.
According to GP2, 4-bromo-1,3-dithiole-2-thione (4b; 1.66 g,
7.80 mmol) was dissolved in anhyd THF (31 mL). TMPMgCl·LiCl (1;
7.73 mL, 8.58 mmol, 1.11 M in THF) was added dropwise at –78 °C
and the mixture was stirred for 0.5 h. The freshly prepared magne-
sium reagent was added to a solution of 1,2-dibromotetrachlo-
roethane (3.04 g, 9.36 mmol) in anhyd THF (15 mL) at –78 °C. The
mixture was allowed to warm up to 25 °C over 12 h, it was then
quenched with sat. aq NH4Cl solution (50 mL) and extracted with Et2O
(3 × 100 mL), and the combined extracts were dried (anhyd Na2SO4).
After filtration, the solvents were evaporated in vacuo. The crude
product was purified by flash column chromatography (silica gel, iso-
hexane) yielding 5a (2.07 g, 91%) as a yellow solid; mp 96–98 °C.
1H NMR (300 MHz, CDCl3): δ = 7.35 (d, J = 8.7 Hz, 2 H), 7.00–6.90 (m, 3
H), 3.85 (s, 3 H).
13C NMR (75 MHz, CDCl3): δ = 212.3, 160.7, 146.2, 127.9, 123.7, 120.0,
114.7, 55.4.
MS (70 eV, EI): m/z (%) = 242 (13), 241 (12), 240 (100) [M+], 164 (40),
149 (70), 121 (18).
HRMS (EI): m/z [M+] calcd for C10H8OS3: 239.9737; found: 239.9724.
4-(3-Nitrophenyl)-1,3-dithiole-2-thione (4m)19
According to GP1, DTT (2; 134 mg, 1.0 mmol) was dissolved in anhyd
THF (2 mL). TMPMgCl·LiCl (1; 0.99 mL, 1.1 mmol, 1.11 M in THF) was
added dropwise at –78 °C and the mixture was stirred for 0.5 h. A
ZnCl2 solution (1.2 mL, 1.2 mmol, 1.0 M in THF) was added at –78 °C
and the mixture was stirred for 15 min. The freshly prepared zinc re-
agent was added to a solution of 1-iodo-3-nitrobenzene (199 mg,
0.8 mmol) and Pd(PPh3)4 (116 mg, 0.10 mmol) in anhyd NMP (1 mL)
IR: 2921, 1077, 978, 876, 867 cm–1
.
13C NMR (101 MHz, CDCl3): δ = 208.7, 107.2.
MS (70 eV, EI): m/z (%) = 294 (63), 292 (100), 290 (45) [M+], 218 (19),
216 (46), 214 (19), 213 (28), 211 (22), 169 (11), 167 (10), 137 (58),
135 (58), 125 (29), 123 (26), 88 (26), 82 (17), 80 (18), 79 (11), 76 (22),
60 (11), 57 (12), 56 (13), 44 (20), 44 (15), 43 (12).
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HRMS (EI): m/z [M+] calcd for C3Br2S3: 289.7529; found: 289.7518.
13C NMR (75 MHz, CDCl3): δ = 210.8, 135.9, 19.2.
MS (70 eV, EI): m/z (%) = 228 (29), 226 (100) [M+], 207 (20), 150 (28),
135 (51), 103 (33), 91 (55), 88 (52), 76 (43), 73 (16), 61 (19), 48 (15),
47 (17), 45 (35), 44 (10), 43 (26).
4-Bromo-5-iodo-1,3-dithiole-2-thione (5b)
According to GP2, 4-bromo-1,3-dithiole-2-thione (4b; 107 mg,
0.50 mmol) was dissolved in anhyd THF (1 mL). TMPMgCl·LiCl (1;
0.50 mL, 0.55 mmol, 1.11 M in THF) was added dropwise at –78 °C
and the mixture was stirred for 0.5 h. The freshly prepared magne-
sium reagent was added to a solution of I2 (152 mg, 0.60 mmol) in an-
hyd THF (1 mL) at –78 °C. The mixture was stirred at this temperature
for 1 h, it was then quenched with sat. aq Na2S2O3 solution (5 mL) and
extracted with Et2O (3 × 10 mL), and the combined extracts were
dried (anhyd Na2SO4). After filtration, the solvents were evaporated in
vacuo. The crude product was purified by flash column chromatogra-
phy (silica gel, isohexane) yielding 5b (186 mg, 70%) as a yellow solid;
mp 126–130 °C.
HRMS (EI): m/z [M+] calcd for C5H6S5: 225.9073; found: 225.9049.
4-Iodo-5-(4-methoxyphenyl)-1,3-dithiole-2-thione (5e)
According to GP2, 4-(4-methoxyphenyl)-1,3-dithiole-2-thione (4l;
240 mg, 1.0 mmol) was dissolved in anhyd THF (10 mL). TMPMgCl·Li-
Cl (1; 0.99 mL, 1.1 mmol, 1.11 M in THF) was added dropwise at –
78 °C and the mixture was stirred for 0.5 h. The freshly prepared
magnesium reagent was added to a solution of I2 (305 mg, 1.2 mmol)
in anhyd THF (1 mL) at –78 °C. The mixture was stirred at this tem-
perature for 1 h, it was then quenched with sat. aq Na2S2O3 solution (5
mL) and extracted with Et2O (3 × 10 mL), and the combined extracts
were dried (anhyd Na2SO4). After filtration, the solvents were evapo-
rated in vacuo. The crude product was purified by flash column chro-
matography (silica gel, isohexane–CH2Cl2, 2:1) yielding 5e (353 mg,
96%) as a yellow solid; mp 169–174 °C (decomp.).
IR: 1483, 1071, 1047, 1018, 878 cm–1
.
13C NMR (75 MHz, CDCl3): δ = 213.1, 112.8, 76.1.
MS (70 eV, EI): m/z (%) = 342 (12), 340 (100), 338 (90) [M+], 264 (16),
262 (15), 213 (58).
HRMS (EI): m/z [M+] calcd for C3BrIS3: 337.7390; found: 337.7383.
IR: 1605, 1491, 1255, 1028, 829 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 7.42 (d, J = 8.6 Hz, 2 H), 6.99 (d, J = 8.3
Hz, 2 H), 3.87 (s, 3 H).
4-Bromo-5-(tert-butyldimethylsilyl)-1,3-dithiole-2-thione (5c)
13C NMR (75 MHz, CDCl3): δ = 214.6, 160.9, 146.4, 130.5, 123.5, 114.4,
68.5, 55.4.
MS (70 eV, EI): m/z (%) = 368 (8), 367 (8), 366 (53) [M+], 164 (11), 163
(100), 119 (9), 94 (9), 93 (8), 76 (5).
According to GP2, 4-bromo-1,3-dithiole-2-thione (4b; 1.06 g,
5.0 mmol) was dissolved in anhyd THF (10 mL). TMPMgCl·LiCl (1;
4.95 mL, 5.50 mmol, 1.11 M in THF) was added dropwise at –78 °C
and the mixture was stirred for 0.5 h. The freshly prepared magne-
sium reagent was added to a solution of TBDMSOTf (1.59 g, 6.0 mmol)
in anhyd THF (10 mL) at –78 °C. The mixture was stirred at this tem-
perature for 1 h, it was then quenched with sat. aq NH4Cl solution (50
mL) and extracted with Et2O (3 × 100 mL), and the combined extracts
were dried (anhyd Na2SO4). After filtration, the solvents were evapo-
rated in vacuo. The crude product was purified by flash column chro-
matography (silica gel, isohexane) yielding 5c (1.55 g, 94%) as a yel-
low solid; mp 50–51 °C.
HRMS (EI): m/z [M+] calcd for C10H7OIS3: 365.8704; found: 365.8702.
4,4′-(2-Thioxo-1,3-dithiole-4,5-diyl)dibenzonitrile (5f)
According to GP2, 4-(2-thioxo-1,3-dithiol-4-yl)benzonitrile (4g;
1.18 g, 5.0 mmol) was dissolved in anhyd THF (50 mL). TMPMgCl·LiCl
(1; 4.95 mL, 5.5 mmol, 1.11 M in THF) was added dropwise at –78 °C
and the mixture was stirred for 0.5 h. A ZnCl2 solution (6.0 mL,
6.0 mmol, 1.0 M in THF) was added at –78 °C and the mixture was
stirred for 15 min. The freshly prepared zinc reagent was added to a
solution of 4-iodobenzonitrile (916 mg, 4.0 mmol) and Pd(PPh3)4
(578 mg, 0.5 mmol) in anhyd NMP (15 mL) at 25 °C. The mixture was
stirred at 25 °C for 5 h, it was then quenched with sat. aq NH4Cl solu-
tion (50 mL) and extracted with EtOAc (3 × 100 mL), and the com-
bined extracts were dried (anhyd Na2SO4). After filtration, the sol-
vents were evaporated in vacuo. The crude product was purified by
flash column chromatography (silica gel, isohexane–CH2Cl2, 1:2)
yielding 4f (1.12 g, 83%) as a yellow solid; mp 184–189 °C (decomp.).
IR: 2924, 2853, 1074, 955, 835, 804, 774, 674 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 1.01 (s, 9 H), 0.41 (s, 6 H).
13C NMR (101 MHz, CDCl3): δ = 215.4, 143.7, 110.6, 26.6, 18.5, –4.1.
MS (70 eV, EI): m/z (%) = 328 (86), 326 (74) [M+], 272 (100), 270 (91),
195 (55), 193 (53), 149 (45), 115 (45), 73 (46), 71 (64), 57 (58).
HRMS (EI): m/z [M+] calcd for C9H15BrS3Si (325.9289): found:
325.9272.
4,5-Bis(methylthio)-1,3-dithiole-2-thione (5d)20
IR: 2226, 1037, 838, 810, 690, 554 cm–1
.
According to GP2, 4-(methylthio)-1,3-dithiole-2-thione (4c; 1.04 g,
5.8 mmol) was dissolved in anhyd THF (23 mL). TMPMgCl·LiCl (1;
5.75 mL, 6.39 mmol, 1.11 M in THF) was added dropwise at –78 °C
and the mixture was stirred for 0.5 h. The freshly prepared magne-
sium reagent was added to a solution of S-methyl methanethiosulfon-
ate (879 mg, 0.72 mL, 6.98 mmol) in anhyd THF (14 mL) at –78 °C. The
mixture was stirred at this temperature for 1 h, it was then quenched
with sat. aq NH4Cl solution (50 mL) and extracted with Et2O
(3 × 100 mL), and the combined extracts were dried (anhyd Na2SO4).
After filtration, the solvents were evaporated in vacuo. The crude
product was purified by flash column chromatography (silica gel, iso-
hexane–Et2O, 95:5) yielding 5d (1.13 g, 86%) as a green-brownish sol-
id; mp 88–96 °C.
1H NMR (300 MHz, CDCl3): δ = 7.63 (d, J = 8.3 Hz, 4 H), 7.31 (d, J = 8.3
Hz, 4 H).
13C NMR (75 MHz, CDCl3): δ = 208.3, 138.5, 134.1, 133.0, 129.8, 117.5,
113.7.
MS (70 eV, EI): m/z (%) = 351 (19), 338 (14), 337 (18), 336 (79) [M+],
324 (12), 320 (100), 266 (20), 246 (26).
HRMS (EI): m/z [M+] calcd for C17H8N2S3: 335.9850; found: 335.9845.
4,5-Bis(4-chlorophenyl)-1,3-dithiole-2-thione (5g)
According to GP2, 4-(4-chlorophenyl)-1,3-dithiole-2-thione (4h;
1.50 g, 6.13 mmol) was dissolved in anhyd THF (60 mL).
TMPMgCl·LiCl (1; 6.07 mL, 6.74 mmol, 1.11 M in THF) was added
dropwise at –78 °C and the mixture was stirred for 0.5. A ZnCl2 solu-
tion (7.36 mL, 7.36 mmol, 1.0 M in THF) was added at –78 °C and the
IR: 1666, 1417, 1054, 1028, 965, 737 cm–1
1H NMR (300 MHz, CDCl3): δ = 2.50 (s, 6 H).
.
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mixture was stirred for 15 min. The freshly prepared zinc reagent was
added to a solution of 1-chloro-4-iodobenzene (1.17 g, 4.90 mmol)
and Pd(PPh3)4 (708 mg, 0.6 mmol) in anhyd NMP (30 mL) at 25 °C. The
mixture was stirred at 25 °C for 12 h, it was then quenched with sat.
aq NH4Cl solution (50 mL) and extracted with EtOAc (3 × 100 mL), and
the combined extracts were dried (anhyd Na2SO4). After filtration, the
solvents were evaporated in vacuo. The crude product was purified
by flash column chromatography (silica gel, isohexane–CH2Cl2, 3:1)
yielding 5g (1.62 g, 93%) as a yellow solid; mp 155–158 °C.
IR: 1064, 1047, 1024, 818, 799 cm–1
1H NMR (300 MHz, CDCl3): δ = 7.10 (s, 8 H), 2.34 (s, 6 H).
13C NMR (75 MHz, CDCl3): δ = 211.0, 139.4, 139.1, 129.6, 129.0, 127.5,
.
21.3.
MS (70 eV, EI): m/z (%) = 316 (15), 315 (20), 314 (99) [M+], 239 (18),
238 (100), 237 (18), 221 (10), 179 (15), 178 (14).
HRMS (EI): m/z [M+] calcd for C17H14S3: 314.0258; found: 314.0254.
IR: 1479, 1398, 1066, 1052, 798 cm–1
.
4-Bromo-1,3-dithiol-2-one (6a)8f
1H NMR (400 MHz, CDCl3): δ = 7.34–7.27 (m, 4 H), 7.18–7.11 (m, 4 H).
13C NMR (101 MHz, CDCl3): δ = 209.7, 138.3, 135.7, 130.4, 129.4,
According to GP3, Hg(OAc)2 (1.91 g, 6.0 mmol) was added portion-
wise to a solution of 4-bromo-1,3-dithiole-2-thione (4b; 426 mg, 2.0
mmol) in CHCl3 (40 mL) and AcOH (12.5 mL) at 25 °C. The mixture
was stirred at this temperature for 1.5 h and the precipitate was then
filtered through Celite. The resulting solution was washed with sat.
aq Na2CO3 (2 × 100 mL) and water (2 × 100 mL). The organic layer was
dried (anhyd Na2SO4) and after filtration, the solvents were evaporat-
ed in vacuo. The crude product was purified by flash column chroma-
tography (silica gel, isohexane–Et2O, 95:5) yielding 6a (337 mg, 86%)
as a colorless solid; mp 60–65 °C.
128.5.
MS (70 eV, EI): m/z (%) = 358 (18), 357 (13), 356 (61), 355 (20), 354
(79) [M+], 281 (10), 278 (100), 246 (21), 208 (29), 201 (12), 199 (37),
176 (17), 163 (12), 155 (12), 139 (13).
HRMS (EI): m/z [M+] calcd for C15H8Cl2S3: 353.9165; found: 353.9161.
4,5-Bis[4-(trifluoromethyl)phenyl]-1,3-dithiole-2-thione (5h)
According to GP2, 4-[4-(trifluoromethyl)phenyl]-1,3-dithiole-2-thi-
one (4i; 1.39 g, 4.99 mmol) was dissolved in anhyd THF (40 mL). TMP-
MgCl·LiCl (1; 4.95 mL, 5.49 mmol, 1.11 M in THF) was added drop-
wise at –78 °C and the mixture was stirred for 0.5 h. A ZnCl2 solution
(5.98 mL, 5.98 mmol, 1.0 M in THF) was added at –78 °C and the mix-
ture was stirred for 15 min. The freshly prepared zinc reagent was
added to a solution of 1-iodo-4-(trifluoromethyl)benzene (1.09 g,
3.99 mmol) and Pd(PPh3)4 (576 mg, 0.5 mmol) in anhyd NMP (20 mL)
at 25 °C. The mixture was stirred at 25 °C for 14 h, it was then
quenched with sat. aq NH4Cl solution (50 mL) and extracted with
EtOAc (3 × 100 mL), and the combined extracts were dried (anhyd
Na2SO4). After filtration, the solvents were evaporated in vacuo. The
crude product was purified by flash column chromatography (silica
gel, isohexane–CH2Cl2, 3:1) yielding 5h (1.50 g, 89%) as a yellow solid;
mp 162–166 °C.
IR: 2928, 1643, 956, 836, 804, 775 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 6.83 (s, 1 H).
13C NMR (75 MHz, CDCl3): δ = 191.4, 117.0, 99.5.
MS (70 eV, EI): m/z (%) = 198 (4), 196 (4) [M+], 170 (5), 168 (5), 111
(4), 97 (5), 89 (10), 88 (6), 84 (6), 83 (5), 73 (7), 71 (6), 70 (16), 69 (7),
61 (19), 57 (8), 55 (7), 45 (17), 45 (4), 43 (5), 43 (100), 42 (6), 41 (5).
HRMS (EI): m/z [M+] calcd for C3HOBrS2: 195.8652; found: 195.8647.
4,4′-(2-Oxo-1,3-dithiole-4,5-diyl)dibenzonitrile (6b)
According to GP3, Hg(OAc)2 (1.91 g, 6.0 mmol) was added portion-
wise to a solution of 4,4′-(2-thioxo-1,3-dithiole-4,5-diyl)dibenzoni-
trile (5f; 673 mg, 2.0 mmol) in CHCl3 (40 mL) and AcOH (12.5 mL) at
25 °C. The mixture was stirred at this temperature for 2 h and the
precipitate was then filtered through Celite. The resulting solution
was washed with sat. aq Na2CO3 (2 × 100 mL) and water (2 × 100 mL).
The organic layer was dried (anhyd Na2SO4) and after filtration, the
solvents were evaporated in vacuo. The crude product was purified
by flash column chromatography (silica gel, isohexane–CH2Cl2, 1:2)
yielding 6b (480 mg, 75%) as a yellow solid; mp 210–214 °C.
IR: 1615, 1316, 1122, 1112, 1065, 1016 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.60 (d, J = 8.2 Hz, 4 H), 7.34 (d, J = 8.0
Hz, 4 H).
13C NMR (101 MHz, CDCl3): δ = 209.2, 138.6, 133.4, 131.6 (q, J = 33.1
Hz), 129.6, 126.3 (q, J = 3.9 Hz), 123.5 (q, J = 272.8 Hz).
19F NMR (376 MHz, CDCl3): δ = –63.0.
MS (70 eV, EI): m/z (%) = 424 (16), 423 (22), 422 (100) [M+], 345 (16),
345 (100), 313 (13), 233 (35), 189 (13), 76 (16).
HRMS (EI): m/z [M+] calcd for C17H8F6S3: 421.9692; found: 421.9687.
IR: 2223, 1656, 840, 830, 554 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 7.60 (d, J = 8.3 Hz, 4 H), 7.31 (d, J = 8.6
Hz, 4 H).
13C NMR (75 MHz, CDCl3): δ = 188.0, 135.5, 132.8, 130.1, 128.8, 117.7,
113.2.
MS (70 eV, EI): m/z (%) = 322 (11), 321 (24), 320 (100) [M+], 293 (17),
292 (74), 291 (13), 260 (31), 229 (12), 228 (66), 215 (15), 207 (10),
147 (10), 146 (94), 102 (17).
HRMS (EI): m/z [M+] calcd for C17H8ON2S2: 320.0078; found:
320.0072.
4,5-Di-p-tolyl-1,3-dithiole-2-thione (5i)
According to GP2, 4-(p-tolyl)-1,3-dithiole-2-thione (4j; 1.09 g,
4.88 mmol) was dissolved in anhyd THF (40 mL). TMPMgCl·LiCl (1;
4.84 mL, 5.37 mmol, 1.11 M in THF) was added dropwise at –78 °C
and the mixture was stirred for 0.5 h. A ZnCl2 solution (5.86 mL,
5.86 mmol, 1.0 M in THF) was added at –78 °C and the mixture was
stirred for 15 min. The freshly prepared zinc reagent was added to a
solution of 4-iodotoluene (851 mg, 3.90 mmol) and Pd(PPh3)4
(564 mg, 0.49 mmol) in anhyd NMP (20 mL) at 25 °C. The mixture was
stirred at 25 °C for 12 h, it was then quenched with sat. aq NH4Cl solu-
tion (50 mL) and extracted with EtOAc (3 × 100 mL), and the com-
bined extracts were dried (anhyd Na2SO4). After filtration, the sol-
vents were evaporated in vacuo. The crude product was purified by
flash column chromatography (silica gel, isohexane–CH2Cl2, 2:1)
yielding 5i (1.09 g, 89%) as a yellow solid; mp 155–158 °C.
4,5-Bis(4-chlorophenyl)-1,3-dithiol-2-one (6c)
According to GP3, Hg(OAc)2 (1.91 g, 6.0 mmol) was added portion-
wise to a solution of 4,5-bis(4-chlorophenyl)-1,3-dithiole-2-thione
(5g; 711 mg, 2.0 mmol) in CHCl3 (40 mL) and AcOH (12.5 mL) at 25 °C.
The mixture was stirred at this temperature for 1 h and the precipi-
tate was then filtered through Celite. The resulting solution was
washed with sat. aq Na2CO3 (2 × 100 mL) and water (2 × 100 mL). The
organic layer was dried (anhyd Na2SO4) and after filtration, the sol-
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vents were evaporated in vacuo. The crude product was purified by
flash column chromatography (silica gel, isohexane–CH2Cl2, 2:1)
yielding 6c (624 mg, 92%) as a yellow solid; mp 141–146 °C.
25 °C, the crude product was purified twice by flash column chroma-
tography (silica gel, isohexane–EtOAc, 98:2) yielding 7b (127 mg,
63%) as a red solid; mp 230–233 °C.
IR: 1648, 1587, 1482, 1090, 827 cm–1
.
IR: 2923, 1320, 1121, 1106, 1066, 842 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.31–7.23 (m, 4 H), 7.19–7.09 (m, 4 H).
1H NMR (600 MHz, CDCl3): δ = 7.57–7.49 (m, 8 H), 7.38–7.29 (m, 8 H).
13C NMR (101 MHz, CDCl3): δ = 189.5, 135.1, 130.7, 129.8, 129.2,
128.0.
13C NMR (151 MHz, CDCl3): δ = 135.6, 130.8 (q, J = 32.8 Hz), 129.4,
126.1, 125.9 (q, J = 3.6 Hz), 123.6 (q, J = 272.4 Hz), 108.7.
MS (70 eV, EI): m/z (%) = 340 (64), 338 (83) [M+], 310 (23), 278 (20),
19F NMR (376 MHz, CDCl3): δ = –62.9.
248 (62), 246 (100), 241 (23), 176 (35), 157 (44), 111 (21).
HRMS (EI): m/z [M+] calcd for C15H8OCl2S2: 337.9394; found:
337.9388.
MS (70 eV, EI): m/z (%) = 781 (11), 780 (24) [M+], 535 (10), 454 (13),
391 (10), 378 (22), 344 (100), 314 (11), 313 (53), 294 (10), 233 (10),
189 (55).
HRMS (EI): m/z [M+] calcd for C34H16F12S4: 779.9943; found: 779.9945.
4,5-Bis[4-(trifluoromethyl)phenyl]-1,3-dithiol-2-one (6d)
According to GP3, Hg(OAc)2 (1.91 g, 6.0 mmol) was added portion-
wise to a solution of 4,5-bis[4-(trifluoromethyl)phenyl]-1,3-dithiole-
2-thione (5h; 845 mg, 2.0 mmol) in CHCl3 (40 mL) and AcOH (12.5
mL) at 25 °C. The mixture was stirred at this temperature for 1 h and
the precipitate was then filtered through Celite. The resulting solu-
tion was washed with sat. aq Na2CO3 (2 × 100 mL) and water (2 × 100
mL). The organic layer was dried (anhyd Na2SO4) and after filtration,
the solvents were evaporated in vacuo. The crude product was puri-
fied by flash column chromatography (silica gel, isohexane–CH2Cl2,
2:1) yielding 6d (736 mg, 91%) as a yellowish solid; mp 123–125 °C.
4,4′-(4′,5′-Di-p-tolyltetrathiafulvalene-4,5-diyl)dibenzonitrile (7c)
According to GP4, 4,5-di-p-tolyl-1,3-dithiole-2-thione (5i; 314 mg,
1.0 mmol) was dissolved in freshly distilled P(OEt)3 (10 mL). 4,4′-(2-
Oxo-1,3-dithiole-4,5-diyl)dibenzonitrile (6b; 384 mg, 1.2 mmol) was
added at 25 °C and the mixture was stirred at 110 °C for 2 h. After
cooling to 25 °C, the crude product was purified twice by flash col-
umn chromatography (silica gel, isohexane–CH2Cl2, 1:1) yielding 7c
(393 mg, 67%) as a brown solid; mp 263–265 °C.
IR: 2225, 849, 838, 813, 802, 778 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.52 (d, J = 8.4 Hz, 4 H), 7.28–7.22 (m, 4
H), 7.11–7.05 (m, 4 H), 7.05–6.97 (m, 4 H), 2.28 (s, 6 H).
13C NMR (101 MHz, CDCl3): δ = 138.5, 136.7, 132.6, 130.0, 129.7,
129.5, 129.3, 128.9, 128.4, 118.0, 112.5, 104.2, 21.3.
MS (70 eV, EI): m/z (%) = 588 (28), 587 (41), 586 (100) [M+], 451 (16),
440 (11), 420 (19), 419 (65), 397 (19), 293 (12), 260 (24), 238 (19),
229 (13), 228 (65), 215 (11), 206 (51), 205 (17), 191 (10), 189 (12),
146 (27), 135 (15), 44 (10).
IR: 1660, 1320, 1123, 1112, 1065, 838 cm–1
.
1H NMR (400 MHz, CDCl3): δ = 7.57 (d, J = 8.2 Hz, 4 H), 7.34 (d, J = 8.2
Hz, 4 H).
13C NMR (101 MHz, CDCl3): δ = 188.9, 134.8, 131.2 (q, J = 32.8 Hz),
129.9, 128.6, 126.0 (q, J = 3.5 Hz), 123.5 (q, J = 272.4 Hz).
19F NMR (376 MHz, CDCl3): δ = –63.0.
MS (70 eV, EI): m/z (%) = 407 (15), 406 (68) [M+], 387 (10), 378 (31),
346 (19), 314 (45), 190 (11), 189 (100), 145 (13), 139 (12).
HRMS (EI): m/z [M+] calcd for C17H8OF6S2: 405.9921; found: 405.9917.
HRMS (EI): m/z [M+] calcd for C34H22N2S4: 586.0666; found: 586.0664.
4,4′-{4′,5′-Bis[4-(trifluoromethyl)phenyl]tetrathiafulvalene-4,5-
4,4′,5,5′-Tetrakis(4-chlorophenyl)tetrathiafulvalene (7a)
diyl}dibenzonitrile (7d)
According to GP4, 4,5-bis(4-chlorophenyl)-1,3-dithiol-2-one (6c; 170
mg, 0.5 mmol) was dissolved in freshly distilled P(OEt)3 (5 mL) and
the mixture was stirred at 110 °C for 3 h. After cooling to 25 °C, the
crude product was purified by flash column chromatography (silica
gel, isohexane–CH2Cl2, 9:1) yielding 7a (87 mg, 54%) as a red solid;
mp 260–262 °C.
According to GP4, 4,4′-(2-thioxo-1,3-dithiole-4,5-diyl)dibenzonitrile
(5f; 122 mg, 0.36 mmol) was dissolved in freshly distilled P(OEt)3
(4 mL). 4,5-Bis[4-(trifluoromethyl)phenyl]-1,3-dithiol-2-one (6d;
177 mg, 0.44 mmol) was added at 25 °C and the mixture was stirred
at 110 °C for 1.5 h. After cooling to 25 °C, the crude product was puri-
fied twice by flash column chromatography (silica gel, isohexane–
CH2Cl2, 1:1) yielding 7d (132 mg, 53%) as a dark red solid; mp 241.2–
246.6 °C.
IR: 1488, 1481, 1089, 1013, 838, 797 cm–1
.
1H NMR (600 MHz, CDCl3): δ = 7.24 (d, J = 8.2 Hz, 8 H), 7.14 (d, J = 8.5
Hz, 8 H).
13C NMR (151 MHz, CDCl3): δ = 134.6, 130.7, 130.3, 129.1, 128.5,
108.4.
IR: 2227, 1321, 1125, 1111, 1067, 846 cm–1
.
1H NMR (600 MHz, CDCl3): δ = 7.61–7.51 (m, 8 H), 7.37–7.26 (m, 8 H).
13C NMR (151 MHz, CDCl3): δ = 136.3, 135.4, 132.7, 130.9 (q, J = 32.8
Hz), 129.9, 129.7, 129.4, 125.9 (q, J = 3.6 Hz), 123.6 (q, J = 272.4 Hz),
117.9, 112.8, 110.0, 107.4.
MS (70 eV, EI): m/z (%) = 650 (19), 649 (21), 648 (60), 647 (34), 646
(100), 645 (23), 644 (62) [M+], 493 (11), 491 (24), 489 (22), 324 (11),
323 (15), 322 (10), 278 (14), 248 (53), 247 (13), 246 (83), 176 (31).
19F NMR (376 MHz, CDCl3): δ = –62.9.
HRMS (EI): m/z [M+] calcd for C30H16Cl4S4: 643.8889; found: 643.8885.
MS (70 eV, EI): m/z (%) = 696 (27), 695 (38), 694 (100) [M+], 505 (11),
347 (17), 314 (39), 228 (32).
HRMS (EI): m/z [M+] calcd for C34H16N2F6S4: 694.0101; found:
694.0095.
4,4′,5,5′-Tetrakis[4-(trifluoromethyl)phenyl]tetrathiafulvalene
(7b)21
According to GP4, 4,5-bis(4-(trifluoromethyl)phenyl)-1,3-dithiol-2-
one (6d; 235 mg, 0.6 mmol) was dissolved in freshly distilled P(OEt)3
(5 mL) and the mixture was stirred at 110 °C for 3 h. After cooling to
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Acknowledgment
Lett. 2013, 15, 1128. (h) Haas, D.; Mosrin, M.; Knochel, P. Org.
Lett. 2013, 15, 6162. (i) Klatt, T.; Blümke, T. D.; Ganiek, M. A.;
Knochel, P. Synthesis 2014, 46, 290. (j) Blanc, R.; Groll, K.;
Bernhardt, S.; Stockmann, P. N.; Knochel, P. Synthesis 2014, 46,
1052. (k) Shen, Z.-L.; Sommer, K.; Knochel, P. Synthesis 2014, 46,
2617.
We thank the SFB 749 for financial support. We thank Rockwood
Lithium (Hoechst) and BASF SE (Ludwigshafen) for the generous gift
of chemicals.
(5) (a) Wunderlich, S. H.; Knochel, P. Angew. Chem. Int. Ed. 2007, 46,
7685. (b) Wunderlich, S. H.; Knochel, P. Org. Lett. 2008, 10, 4705.
(c) Wunderlich, S.; Knochel, P. Chem. Commun. 2008, 6387.
(d) Kienle, M.; Dunst, C.; Knochel, P. Org. Lett. 2009, 11, 5158.
(e) Mosrin, M.; Knochel, P. Chem. Eur. J. 2009, 15, 1468.
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Supporting Information
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0035-1560728.
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