Sulfanyl-substituted [3]cumulenes and buta-1,3-dienes from a tetrakis(pyridinium)-substituted butadiene

Article abstract of DOI:10.1055/s-0029-1216861

Treatment of perchlorobuta-1,3-diene with 4-(N,N-dimethylamino) pyridine resulted in the formation of 1,1′,1″,1?-(2,3-dichlorobuta-1, 3-iene-1,1,4,4-tetrayl)tetrakis[4-(dimethylamino) pyridinium] tetrachloride (structure confirmed by X-ray analysis), whic

Full text of DOI:10.1055/s-0029-1216861

PAPER
2371
Sulfanyl-Substituted [3]Cumulenes and Buta-1,3-dienes from a
Tetrakis(pyridinium)-Substituted Butadiene
S
ulfanyl-Substitute
n
d [3]Cumule
d
nes
a
nd But
r
a-1,3-die
e
nes as Schmidt,*a Alireza Rahimi,a Mimoza Gjikajb
a
Institute of Organic Chemistry, Clausthal University of Technology, Leibnizstraße 6, 38678 Clausthal-Zellerfeld, Germany
Fax +49(5323)723861; E-mail: schmidt@ioc.tu-clausthal.de
b
Institute of Inorganic Chemistry, Clausthal University of Technology, Paul-Ernst-Straße 4, 38678 Clausthal-Zellerfeld, Germany
Received 22 January 2009; revised 9 April 2009
In our previous work, 4-(dimethylamino)pyridinium rings
proved to be highly versatile ligands for the stabilization
of reactive species19 or for the activation of various sub-
strates toward substitution reactions. Thus, 4-(dimethyl-
Abstract: Treatment of perchlorobuta-1,3-diene with 4-(N,N-di-
methylamino)pyridine resulted in the formation of 1,1¢,1¢¢,1¢¢¢-
(2,3-dichlorobuta-1,3-diene-1,1,4,4-tetrayl)tetrakis[4-(dimethylami-
no)pyridinium] tetrachloride (structure confirmed by X-ray analy-
sis), which was converted into persulfurated butatrienes amino)pyridinium-substituted heteroaromatics such as
([3]cumulenes), pentakis(sulfanyl)-substituted buta-1,3-dienes, or
pyridine can be used for the synthesis of a broad variety of
functionalized pyridines.20 We describe here an efficient
tetrakis(sulfanyl)-substituted 2,3-dichlorobuta-1,3-dienes by reac-
tions with thiolates or a sulfinate. The outcome of the reaction de-
synthesis of sulfanyl-substituted butatrienes ([3]cumu-
pends on the reaction conditions and the substitution pattern of the
lenes) and butadienes, which avoids potentially explosive
starting sulfur nucleophiles.
starting materials or time-consuming syntheses of starting
Key words: dienes and trienes, sulfides, pyridines, perchlorinated
materials. Our synthesis starts from a tetrakis[4-(dimethyl-
compounds, persulfurated compounds
amino)pyridinium]-substituted 2,3-dichlorobuta-1,3-di-
ene, which is readily available on reaction of
commercially available hexachlorobutadiene and 4-(N,N-
Currently, considerable attention is paid to compounds
dimethylamino)pyridine.
with high sulfur content as they play a crucial role in ma-
terials chemistry, supramolecular chemistry, polymer
Thus, reaction of hexachlorobuta-1,3-diene (1) with an
excess of 4-(N,N-dimethylamino)pyridine in 1,2-dichlo-
chemistry, nanochemistry, and biochemistry. A review
robenzene (1,2-DCB) at reflux temperature gave the tar-
summarizing the syntheses and properties of persulfurat-
ed aromatic compounds appeared recently.1 In materials
chemistry, persulfurated compounds are used as electron-
ic conductors,2 organic ferromagnets,3 single-molecule
magnets,4 multivalent conducting and magnetic materi-
als,5 electron-accepting supramolecules,6 optical materi-
als,7 and multifunctional8 as well as electrophotographic
materials.9 Ligands possessing persulfurated benzene
cores for metal sensing devices have been developed.10 In
polymer chemistry, they have found interest as stabilizers1
or, very recently, as high-refractive-index and transparent
polymers.11 Some compounds have been developed as ef-
ficient catalysts in the synthesis of gold nanoparticles.12
The biological relevance of persulfurated compounds is
demonstrated by work dealing with the syntheses of ana-
logues of the C-cluster of Carboxydothermus hydrogeno-
formans carbon monoxide dehydrogenase13 or reactivity
analogues of biotin synthase and other members of the S-
adenosylmethionine enzyme family.14 With respect to
this, butatrienes and butadienes with high sulfur content
constitute a hitherto underexploited class of compounds,15
although they can serve as starting materials for new
sulfanyl-substituted butadienes,16 functionalized thio-
phenes,17 and 1,2-dithiins.18
get starting material 1,1¢,1¢¢,1¢¢¢-(2,3-dichlorobuta-1,3-
diene-1,1,4,4-tetrayl)tetrakis[4-(dimethylamino)pyridini-
um] tetrachloride (2) in 75% yield as a yellow solid
(Scheme 1).
The 1H NMR spectra of 2 show two different types of het-
eroaromatic ring systems. In agreement with the proposed
Cl
Cl
Cl
Cl
Cl Cl
1
DMAP (4 equiv)
1,2-DCB, 6 h
(75%)
NMe2
4 Cl–
N
Me2N
N
Cl
Cl
N
NMe2
N
Me2N
2
SYNTHESIS 2009, No. 14, pp 2371–2378
x
x.
x
x
.
2
0
0
9
Advanced online publication: 29.05.2009
DOI: 10.1055/s-0029-1216861; Art ID: T01709SS
Scheme 1 Synthesis of the starting material
© Georg Thieme Verlag Stuttgart · New York

2372
A. Schmidt et al.
PAPER
structure, the HMBC (1H–13C) spectrum displays all the previously prepared from buta-1,3-diyne-1,4-diyldilithi-
expected long-range C–H couplings. Single crystals of 2 um – available from 1,4-dichlorobut-2-yne via the poten-
suitable for an X-ray single-crystal analysis were obtained tially explosive buta-1,3-diyne22 – with electrophilic
by slow evaporation of a saturated solution in acetoni- dichalcogenides RSSR.18 The tert-butyl-, cyclohexyl-,
trile–methanol (95:5). The substance crystallized with one benzyl-, and phenyl derivatives 3d–g were earlier synthe-
molecule of hydrogen chloride, in addition to water of sized starting from tetrachlorobut-1-en-3-yne in 36–62%
crystallization. The molecular drawing is shown in yields.23,24 This perchlorobutenyne, however, must be pre-
Figure 1. The twisted buta-1,3-diene core adopts an s- pared from perchlorobutadiene and butyllithium in low
trans conformation. The dihedral angle Cl–C2–C3–Cl yield,25 or from 1,1,3,3,4,4-hexachlorobut-1-ene,26 pen-
was determined to be 67.7(7)°. The bond lengths of C1– tachlorobutadiene,26 or other chlorinated precursors.26,27
C2 and C3–C4 of the butadiene are identical, and were de- In some cases, mixtures of compounds are formed by this
termined to be 133.4(7) pm. The bond C2–C3 has a length procedure.28 An exception is the tert-butyl derivative 3d,
of 147.3(7) pm. The pyridinium rings are twisted out of which is also formed from perchlorobutadienes with sodi-
planarity. The pyridinium rings in the Z- and E-positions um 2-methylpropane-2-thiolate.21
at C1 adopt torsion angles of 59.7(7)° and –128.8°, re-
spectively, whereas those at C4 have dihedral angles of
RS
RS
SR
SR
RS– Na+, DMSO, r.t.
C
C
C
C
51.8(7)° (Z) and –131.6(7)° (E). The intramolecular hy-
drogen bond linkages [C7–H7···Cl7 375.0(1) pm, C9–
H9···Cl6 333.8(3) pm, C19–H19···Cl5 337.3(3) pm, C34–
H34···Cl3 380.5(7) pm; crystallographic numbering] be-
tween the pyridine rings and chloride counter anions lead
to the formation of ion pairs that correspond to a formula
unit of [C32H40Cl2N8]Cl4. These ion pairs are further
linked into a three-dimensional supramolecular structure
by intermolecular O–H···Cl and O–H···O hydrogen bonds.
The hydrogen bond distances between the oxygen atoms
of the water molecules and the chloride ions range from
305.2 to 331.4 pm, the O–H···Cl angles from 156.6 to
176.4°. The hydrogen bond distances O–H···O between
the water molecules range from 274.2 to 285.4 pm, and
the O–H···O angles range from 155.6 to 166.6°.
3a–i
RS
1. RS– Na+, DMSO, r.t.
2. H2O
H
SR
2
RS
SR
SR
4a–i
RS
RS– Na+, DMSO
r.t. to 80 °C
Cl
SR
RS
Cl
SR
5a–e
Scheme 2 Formation of [3]cumulenes and butadienes from 2
Sodium p-toluenesulfinate reacted with 2 to provide the
2,3-dichlorobuta-1,3-diene 6 in 72% yield (Scheme 3).
Ts
Cl
Ts
TolS(O)ONa
DMSO, 70 °C
2
Ts
Cl
Ts
Figure 1 Molecular drawing of butadiene 2
6
Scheme 3 Formation of a 2,3-dichloro-1,1,4,4-tetrasulfonyl-substi-
tuted butadiene
Reaction of the pyridinium salt 2 with an excess of the ap-
propriate thiolate in anhydrous dimethyl sulfoxide result-
ed in the smooth formation of the persulfurated
[3]cumulenes 3a–i in reasonable to high yields in one step
at room temperature (Scheme 2, Table 1, entries 1–9).
Various bases, including triethylamine, potassium tert-
butoxide, sodium methoxide, n-butyllithium, and sodium
amide, were screened for preparing the thiolates from the
corresponding thiols. The best results were obtained with
sodium amide. When starting material 2 is used, the for-
mation of mixtures of mono- and disubstituted butadienes
is obviously avoided, whereas these are formed when per-
chlorobutadiene is used.21 The [3]cumulenes 3a–c were
When the reaction mixture for the formation of 3a
(R = Me) is quenched with aqueous dimethyl sulfoxide, a
spontaneous addition of methanethiol to the central
double bond of the butatriene occurs to give the penta-
kis(methylsulfanyl)-substituted buta-1,3-diene 4a in ex-
cellent yield (81%) (Scheme 2, Table 1, entry 10).
Similarly, we prepared, as examples, 4b,c and 4e–h by
this known procedure21 (entries 11, 12, and 14–17). The
tert-butyl-substituted cumulene 3d is inert, so that synthe-
Synthesis 2009, No. 14, 2371–2378 © Thieme Stuttgart · New York

PAPER
Sulfanyl-Substituted [3]Cumulenes and Buta-1,3-dienes
2373
starting from the sodium salt of diethylcarbamodithioic
acid and potassium O-ethylcarbonodithioate, respective-
ly. The imidazole derivative 5e was prepared by the reac-
tion of sodium N-methylimidazole-2-thiolate with 2 at
60 °C (entry 23). The 1H and 13C NMR spectra show two
different types of imidazole rings. Mass spectra as well as
elemental analyses of 5a–e confirm two chlorine atoms in
the molecules.
Table 1 Synthesis of [3]Cumulenes 3a–i and Butadienes 4a–i and
5a–ea
Entry
1
Product
3a
3b
3c
R
Yieldb (%)
75
72
67
83
74
63
57
87
47
81
77
41
0
Me
2
Et
3
i-Pr
The reactions leading to the [3]cumulenes must involve a
reduction of the starting material 2, for which two mecha-
nisms can be envisaged: Sequential nucleophilic substitu-
tion of the 4-(dimethylamino)pyridinium ligands by the
thiolates is supposed to proceed by an addition–elimina-
tion mechanism and to result in the butadiene 2A
(Scheme 4). On the one hand, attack of an additional thi-
olate at position 1 of 2A in an SN2¢-type reaction can result
in the formation of allene 2B, with chloride as the leaving
group. Attack of a second thiolate on the sulfur atom of a
sulfanyl substituent can then give a disulfide by oxidation
and concomitant reduction of 2B to form butatriene 3. In-
deed, a 1:1 ratio of either methanethiolate and tert-butane-
thiolate, or ethanethiolate and tert-butanethiolate,
respectively, resulted in the formation of a mixture of
compounds, from which an adduct such as intermediate
2B was identified as a peak at m/z = 402 and m/z = 416,
respectively. On the other hand, attack of the thiolate on
the chlorine substituent at position 2 of the butadiene 2A
can result in the formation of butatriene 3, chloride, and
the alkanesulfenyl chloride (RSCl). This could react with
excess thiolate to give a disulfide and chloride. We isolat-
ed, in accordance with either pathway, disulfides such as
diphenyl disulfide, di-tert-butyl disulfide, dibenzyl disul-
fide, and dicyclohexyl disulfide in good yields. The spec-
4
3d
3e
t-Bu
5
c-Hex
Bn
6
3f
7
3g
3h
3i
Ph
8
3-MeOC6H4
CH2CO2Me
Me
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
4a
4b
4c
Et
i-Pr
4d
4e
t-Bu
c-Hex
Bn
67
79
77
81
0
4f
4g
4h
4i
Ph
3-MeOC6H4
CH2CO2Me
4-pyridyl
Ac
5a
5b
5c
66
51
79
67
Cl
Cl
C(=S)NEt2
C(=S)OEt
Cl
SR
SR
RS
RS
RS
SR
5d
5e
RS
SR
RS
3-methylimidazol-2-yl 53
RS–
RS
a Reagents and conditions: RS–Na+, DMSO, r.t. (3a–i, 4a–i, 5a,c) or
50–80 °C (5b,d,e).
4 RS–
2A
2B
2
– 4 DMAP
b Yields of pure, isolated products.
– RSSR
RS–
sis of 4d failed (entry 13). Under analogous reaction con-
ditions, 4i decomposed (entry 18).
Cl
Cl
RS
RS
SR
SR
C
C
C C
– RSCl
RS
SR
To the best of our knowledge, only three examples of
buta-1,3-dienes with the 2,3-dichloro-1,1,4,4-tetrasulfa-
nyl substitution pattern have been described to date.17,21,29
The butadiene 5a, which is a new example, is the main
product of the reaction of pyridine-4-thiol with the tetra-
cation 2 in the presence of sodium methoxide (Scheme 2;
Table 1, entry 19). The NMR spectra of 5a clearly show
two distinct types of pyridine rings, and a symmetric mol-
ecule, as only eight resonance frequencies are detected by
13C NMR spectroscopy. The reactions of 2 with sodium
thioacetate required higher temperatures and yielded 5b
(Table 1, entry 20). Compounds 5c,d were obtained in
reasonable yields by this procedure (entries 21 and 22)
RS
SR
3
2A
4
RSH
RSH
RS
RS
SR
RSH
SR
SR
RS
RS
SR
H
SR
3′
7
Scheme 4 Proposed mechanisms
Synthesis 2009, No. 14, 2371–2378 © Thieme Stuttgart · New York

2374
A. Schmidt et al.
PAPER
ference Fourier synthesis. The hydrogen atom of HCl could not be
located.
tra showed no hint of the formation of but-1-en-3-yne 3¢.
It was proposed earlier for related systems that the inter-
conversion of 3/3¢ is reversible when proton-donating Crystal structure data for compound 2: C64H118Cl13N16O18, chemical
formula weight 1860.59 g·mol–1, space group P1 (triclinic),
a = 9.549(1) Å, b = 13.726(2) Å, c = 17.619(2) Å, a = 94.58(1)°,
b = 91.30(1)°, g = 101.11(1)°, V = 2257.1(5) Å3, Z = 1, DC = 1.369
g·cm–3, F(000) = 979, 7894 independent reflections, 734 parame-
ters, R1 = 0.0526, wR2 = 0.1371 [I > 2s(I)], goodness-of-fit on
F2 = 1.042, residual electron density 0.395 and –0.844 e Å–3.
CCDC 710964 contains the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
agents are absent.24 In agreement with the proposed struc-
tures 4, the gs-HMBC (1H–13C) spectra display all expect-
ed long-range C–H couplings for the olefinic proton. The
HMBC correlation shows a 4JCH coupling with one, and a
3JCH coupling with two carbon atoms. Thus, the alterna-
tive structure 7 was excluded from consideration.
In summary, we present an easy access to persulfurated
[3]cumulenes and sulfanyl-substituted buta-1,3-dienes
starting from 4-(N,N-dimethylamino)pyridine and com-
mercially available perchlorobutadiene. The method de-
Buta-1,2,3-trienes 3a–d; General Procedure
scribed here broadens the interesting synthetic The salt 2 (0.454 g, 0.5 mmol) was dissolved in anhyd DMSO (15
mL). A soln of the appropriate sodium thiolate (3 mmol) in DMSO
applicability of polyhetarenium salts developed by Streit-
wieser,30 Weiss,31 and our group.19,20
(10 mL) was added dropwise over 15 min under N2. The reaction
mixture was then filtered through silica gel and extracted with
CH2Cl2 (3 × 35 mL). The organic layers were combined, dried
(MgSO4), and concentrated in vacuo to give dark oils. Flash chro-
matography (silica gel, PE–EtOAc) afforded the products.
The 1H and 13C NMR spectra were recorded on Bruker Avance 400
and Avance DPX-200 spectrometers. The internal standard was
TMS for measurements of samples as solns in CDCl3 and D2O. FT-
IR spectra were obtained on a Bruker Vektor 22 in the range 400–
4000 cm–1. Solids were prepared as pellets (2.5%) in KBr and oils
were prepared as films on NaCl plates. The mass spectra were mea-
sured with a Hewlett Packard HP 5989 instrument. The ESI mass
spectra were measured with an Agilent LCMSD series HP 1100 in-
strument with APIES. Melting points are uncorrected and were de-
termined on an apparatus according to Dr. Tottoli (Büchi). Yields
are not optimized.
1,1,4,4-Tetrakis(methylsulfanyl)butatriene (3a)
A soln of NaSMe (0.21 g, 3 mmol) in DMSO (10 mL) was added to
a soln of the salt 2. After column chromatography (silica gel, PE–
EtOAc, 20:1) a yellow oil was obtained.
Yield: 88 mg (75%).
All data are in agreement with those published earlier.18
Anal. Calcd for C8H12S4: C, 40.64; H, 5.12. Found: C, 41.01; H,
5.03.
1,1¢,1¢¢,1¢¢¢-(2,3-Dichlorobuta-1,3-diene-1,1,4,4-tetrayl)tetra-
kis[4-(dimethylamino)pyridinium] Tetrachloride (2)
Hexachlorobuta-1,3-diene (1; 1.04 g, 4 mmol) was dissolved in 1,2-
dichlorobenzene (100 mL), and DMAP (1.20 g, 10 mmol) was then
added. After the mixture had been kept at reflux temperature for 6
h, a solid precipitated, which formed a yellow solid after recrystal-
lization from MeCN–MeOH (95:5).
1,1,4,4-Tetrakis(ethylsulfanyl)butatriene (3b)
NaSEt (0.25 g, 3 mmol) gave 3b as a yellow oil after chromatogra-
phy (PE–EtOAc, 20:1).
Yield: 105 mg (72%).
All data are in agreement with those published earlier.18
Anal. Calcd for C12H20S4: C, 49.27; H, 6.89. Found: C, 48.93; H,
6.67.
Yield: 2.71 g (75%); mp 235–238 °C (dec).
IR (KBr): 3406, 3055, 1644, 1586, 1406, 1211, 1161, 828 cm–1.
1H NMR (400 MHz, D2O): d = 8.06 (d, J = 7.8 Hz, 4 H, aH), 7.99
(d, J = 7.8 Hz, 4 H, aH), 7.18 (d, J = 7.8 Hz, 4 H, bH), 7.08 (d,
J = 7.8 Hz, 4 H, bH), 3.40 (s, 12 H, NMe2), 3.37 (s, 12 H, NMe2).
1,1,4,4-Tetrakis(isopropylsulfanyl)butatriene (3c)
NaSi-Pr (0.3 g, 3 mmol) gave 3c as a yellow oil after chromatogra-
phy (PE–EtOAc, 20:1).
13C NMR (100 MHz, D2O): d = 157.2 (2 C), 156.9 (2 C), 139.5 (4
C), 139.4 (4 C), 137.5 (2 C), 119.9 (2 C), 109.7 (4 C), 108.7 (4 C),
41.0 (4 C), 40.7 (4 C).
Yield: 116 mg (67%).
All data are in agreement with those published earlier.18
Anal. Calcd for C16H28S4: C, 55.12; H, 8.09. Found: C, 54.46; H,
8.01.
ESI-MS: m/z [M + 3Cl–]+ = 712.8.
Anal. Calcd for C32H40Cl6N8·9H2O: C, 42.10; H, 6.41; N, 12.29.
Found: C, 41.73; H, 5.95; N, 12.20.
1,1,4,4-Tetrakis(tert-butylsulfanyl)butatriene (3d)
This compound has been mentioned before in the literature, but was
not characterized completely.23,24
X-ray Crystal Structure Analysis of 2
A suitable single crystal of the title compound was selected under a
polarization microscope and mounted in a glass capillary (d = 0.5
mm). The crystal structure was determined by X-ray diffraction
analysis using graphite monochromated Mo Ka radiation (0.71073
Å) [T = 223(2) K], whereas the scattering intensities were collected
with a single-crystal diffractometer (STOE IPDS II). The crystal
structure was solved by direct methods using SHELXS-97 and re-
fined using alternating cycles of least squares refinements against
F2 (SHELXL-97).32 All non-hydrogen atoms were located in differ-
ence Fourier maps and were refined with anisotropic displacement
parameters. The hydrogen positions were determined by a final dif-
NaSt-Bu (0.34 g, 3 mmol) gave 3d as yellow crystals after chroma-
tography (PE–EtOAc, 20:1).
Yield: 168 mg (83%); mp 170–171 °C (Lit.23,24 170–171 °C).
IR (KBr): 2959, 2919, 1557, 1453, 1162 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.45 (s, 36 H, CH3).
13C NMR (50 MHz, CDCl3): d = 154.8, 107.4, 49.3, 30.8.
MS (EI, 70 eV): m/z (%) = 404 [M+] (85).
Anal. Calcd for C20H36S4: C, 59.35; H, 8.96. Found: C, 59.41; H,
8.74.
Synthesis 2009, No. 14, 2371–2378 © Thieme Stuttgart · New York

PAPER
Sulfanyl-Substituted [3]Cumulenes and Buta-1,3-dienes
2375
Buta-1,2,3-trienes 3e–i; General Procedure
1H NMR (200 MHz, CDCl3): d = 7.22 (t, J = 7.2 Hz, 4 H), 7.19–7.08
NaNH2 (0.156 g, 4 mmol) was dissolved in anhyd MeCN (15 mL)
at r.t., and the appropriate thiol RSH (4 mmol) was added in one
portion. The mixture was then stirred for 3 h. The precipitate was
collected by filtration, washed several times with anhyd Et2O under
an inert atmosphere, and dried in vacuo. A sample of the thus
formed salt RSNa (3 mmol) was then dissolved in anhyd DMSO (10
mL) and added dropwise to a soln of 2 (0.454 g, 0.5 mmol) within
15 min. The mixture was then filtered through silica gel. The prod-
uct was finally extracted with CH2Cl2 (3 × 35 mL), and the organic
layers were combined and dried (MgSO4). The solvent was evapo-
rated and the residue was subjected to column chromatography.
(m, 8 H), 6.80–6.75 (m, 4 H), 3.78 (s, 12 H).
13C NMR (50 MHz, CDCl3): d = 160.0, 146.7, 138.3, 129.9, 119.6,
113.1, 112.6, 107.3, 55.3.
MS (EI, 70 eV): m/z (%) = 604 [M+] (80).
Anal. Calcd for C32H28O4S4: C, 63.55; H, 4.67. Found: C, 63.37; H,
4.42.
Tetramethyl 2,2¢,2¢¢,2¢¢¢-(Butatriene-1,1,4,4-tetrayltetrasulfane-
tetrayl)tetraacetate (3i)
HSCH2CO2Me (0.425 g, 4 mmol) was used to prepare the salt, of
which a sample (0.384 g, 3 mmol) was reacted with 2. A yellow oil
was obtained after chromatographic workup (silica gel, PE–EtOAc,
2:1).
1,1,4,4-Tetrakis(cyclohexylsulfanyl)butatriene (3e)
This compound has been mentioned before in the literature, but was
not characterized completely.23,24
Yield: 110 mg (47%).
IR (NaCl, thin film): 2954, 2845, 1710, 1556, 1436, 1008 cm–1.
1H NMR (200 MHz, CDCl3): d = 3.75 (s, 12 H, CH3), 3.71 (s, 8 H,
c-HexSH (0.465 g, 4 mmol) was used. A sample of its salt (0.414 g,
3 mmol) was then reacted with 2. Chromatographic separation (sil-
ica gel, PE–EtOAc, 25:1) gave a colorless solid.
CH2).
Yield: 188 mg (74%); mp 83–85 °C (Lit.23,24 86–87 °C).
IR (KBr): 2933, 2852, 1536, 1447, 1197 cm–1.
1H NMR (200 MHz, CDCl3): d = 2.73–2.61 (m, 4 H), 2.08–2.00 (m,
13C NMR (50 MHz, CDCl3): d = 168.8, 148.9, 108.4, 52.8, 36.6.
MS (EI, 70 eV): m/z (%) = 408 [M+ – 2OMe] (45), 292 [M+ –
4COOMe] (75).
8 H), 1.81–1.56 (m, 12 H), 1.43–1.22 (m, 20 H).
Anal. Calcd for C16H20O8S4: C, 41.01; H, 4.30. found: C, 41.43; H,
4.13.
13C NMR (50 MHz, CDCl3): d = 145.6, 106.1, 49.9, 32.8, 26.1, 25.7.
MS (EI, 70 eV): m/z (%) = 508 [M+] (100).
Pentakis(sulfanyl)buta-1,3-dienes 4; General Procedure
Anal. Calcd for C28H44S4: C, 66.08; H, 8.71. Found: C, 65.79; H,
8.83.
The salt 2 (0.454 g, 0.5 mmol) was dissolved in anhyd DMSO (15
mL) and a soln of the appropriate sodium thiolate RSNa (3 mmol)
in DMSO (10 mL) was added dropwise within 15 min under an inert
gas atmosphere. H2O (10 mL) was then added. The products were
extracted with CH2Cl2 (3 × 35 mL). The organic layers were com-
bined, dried (MgSO4), and concentrated to give a dark oil. Flash
chromatography (silica gel, PE–EtOAc) afforded the products.
1,1,4,4-Tetrakis(benzylsulfanyl)butatriene (3f)
This compound has been mentioned before in the literature, but was
not characterized completely.23,24
BnSH (0.497 g, 4 mmol) was used to prepare the salt, of which a
sample (0.438 g, 3 mmol) was used for the reaction with 2. Chroma-
tography (silica gel, PE–EtOAc, 15:1) gave 3f.
Yield: 170 mg (63%); mp 85–87 °C (Lit.23,24 86–87 °C).
IR (KBr): 3053, 3027, 2911, 1573, 1453, 1070 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.27 (m, 20 H), 3.59 (s, 8 H).
13C NMR (50 MHz, CDCl3): d = 149.2, 137.4, 129.4, 128.5, 127.4,
108.6, 43.3.
MS (EI, 70 eV): m/z (%) = 540 [M+] (74).
1,1,2,4,4-Pentakis(methylsulfanyl)buta-1,3-diene (4a)
A soln of NaSMe (0.28 g, 4 mmol) in DMSO (10 mL) was used. Af-
ter column chromatography (silica gel, PE–EtOAc, 20:1) a yellow
oil was obtained.
Yield: 115 mg (81%).
IR (NaCl, thin film): 2985, 2917, 1560, 1430, 444 cm–1.
1H NMR (200 MHz, CDCl3): d = 6.13 (s, 1 H, =CH), 2.39 (s, 3 H,
CH3), 2.36 (s, 3 H, CH3), 2.34 (s, 3 H, CH3), 2.27 (s, 3 H, CH3), 2.21
(s, 3 H, CH3).
Anal. Calcd for C32H28S4: C, 71.07; H, 5.22. Found: C, 71.20; H,
5.03.
13C NMR (50 MHz, CDCl3): d = 139.8, 139.1, 128.8, 123.9, 17.6,
17.2, 17.0, 16.4, 16.3.
MS (EI, 70 eV): m/z (%) = 284 [M+] (100).
1,1,4,4-Tetrakis(phenylsulfanyl)butatriene (3g)
NaSPh (0.4 g, 3 mmol) gave 3g as a yellow solid after purification
by chromatography (PE–EtOAc, 15:1).
Yield: 138 mg (57%); mp 100–101 °C (Lit.23,24 100–100.5 °C).
All data are in agreement with those published earlier.23,24
MS (EI, 70 eV): m/z (%) = 484 [M+] (100).
Anal. Calcd for C9H16S5: C, 37.99; H, 5.67. Found: C, 37.73; H,
5.87.
1,1,2,4,4-Pentakis(ethylsulfanyl)buta-1,3-diene (4b)
This compound has been mentioned before in the literature, but was
not characterized completely.28
Anal. Calcd for C28H20S4: C, 69.38; H, 4.16. Found: C, 69.50; H,
4.21.
A soln of NaSEt (0.33 g, 4 mmol) in DMSO (10 mL) was used. Af-
ter column chromatography (silica gel, PE–EtOAc, 20:1) a yellow
oil was obtained.
1,1,4,4-Tetrakis(3-methoxyphenylsulfanyl)butatriene (3h)
3-Methoxybenzenethiol (0.56 g, 4 mmol) was used to prepare the
salt, of which a sample (0.48 g, 3 mmol) was reacted with 2. Chro-
matography (silica gel, PE–EtOAc, 12:1) gave a yellow solid.
Yield: 136 mg (77%).
13C NMR (50 MHz, CDCl3): d = 141.2, 136.5, 129.9, 127.6, 28.5,
28.4, 27.8, 27.5 (2 C), 15.3, 15.2, 15.1, 14.9, 14.7.
MS (EI, 70 eV): m/z (%) = 354 [M+] (100).
Yield: 263 mg (87%); mp 109–111 °C.
IR (NaCl, thin film): 3063, 2961, 1692, 1578, 1556, 1436, 1268
cm–1.
Anal. Calcd for C14H26S5: C, 47.41; H, 7.39. Found: C, 47.72; H,
7.18.
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A. Schmidt et al.
PAPER
1,1,2,4,4-Pentakis(isopropylsulfanyl)buta-1,3-diene (4c)
A soln of NaSi-Pr (0.4 g, 4 mmol) in DMSO (10 mL) was used. Af-
ter column chromatography (silica gel, PE–EtOAc, 20:1) a yellow
oil was obtained.
A soln of NaSPh (0.53 g, 4 mmol) in DMSO (10 mL) was used. Af-
ter column chromatography (silica gel, PE–EtOAc, 20:1) yellow
crystals were obtained.
Yield: 229 mg (77%); mp 77–78 °C (Lit.24 78–79 °C).
Yield: 0.087 g (41%).
IR (NaCl, thin film): 2954, 2895, 1561, 1430 cm–1.
1H NMR (200 MHz, CDCl3): d = 6.45 (s, 1 H, =CH), 3.73–3.26 (m,
13C NMR (50 MHz, CDCl3): d = 142.3, 137.8, 134.7, 134.0, 133.4,
132.8, 132.7, 132.6, 132.4, 131.2, 130.9, 129.7, 129.0, 128.7, 128.6,
128.3, 128.0, 127.6, 127.5, 127.1, 127.0 (some signals overlap).
5 H, CH), 1.36–1.25 (m, 30 H, CH3).
13C NMR (50 MHz, CDCl3): d = 137.9, 134.7, 130.5, 127.7, 41.6,
Anal. Calcd for C34H26S5: C, 68.64; H, 4.41. Found: C, 68.43; H,
4.19.
41.3, 39.2, 38.9, 23.3, 23.2, 23.0, 22.6, 22.3, 21.9.
MS (EI, 70 eV): m/z (%) = 424 [ M+] (100).
1,1,2,4,4-Pentakis(3-methoxyphenylsulfanyl)buta-1,3-diene
(4h)
NaNH2 (0.156 g, 4 mmol) was dissolved in anhyd MeCN (15 mL)
at r.t. and 3-methoxybenzenethiol (0.56 g, 4 mmol) was added in a
single portion. The mixture was stirred for 3 h. The precipitate was
filtered and washed several times with anhyd Et2O under N2. The
solid was dried under vacuum. The prepared sodium salt was dis-
solved in DMSO (10 mL) and was added to a soln of 2 (0.454 g, 0.5
mmol). H2O (10 mL) was added and the adduct was extracted with
CH2Cl2 (3 × 35 mL). The organic layers were combined and dried
(MgSO4). The solvent was evaporated and after column chromatog-
raphy (silica gel, PE–EtOAc, 10: 1) a yellow oily solid was ob-
tained.
Anal. Calcd for C19H36S5: C, 53.72; H, 8.54. Found: C, 53.51; H,
8.13.
1,1,2,4,4-Pentakis(cyclohexylsulfanyl)buta-1,3-diene (4e)
This compound has been mentioned before in the literature, but was
not characterized completely.24
NaNH2 (0.156 g, 4 mmol) was added to anhyd MeCN (15 mL) at r.t.
and c-HexSH (0.47 g, 4 mmol) was added in one portion. The mix-
ture was stirred for 3 h. The precipitate was collected by filtration,
washed several times with anhyd Et2O under N2, and dried in vacuo.
This salt was then dissolved in DMSO (10 mL) and added to a soln
of 2 (0.454 g, 0.5 mmol). The product was extracted with CH2Cl2
(3 × 35 mL) after quenching with H2O. The organic layers were
combined and dried (MgSO4). Finally, the solvent was evaporated
and the resulting residue was subjected to column chromatography
(silica gel, PE–EtOAc, 25:1); this gave a yellow oil.
Yield: 301 mg (81%).
IR (NaCl, thin film): 3072, 3001, 2935, 2833, 1589, 1477, 1246,
1039 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.23–6.70 (m, 20 H, aryl), 6.46 (s,
1 H, =CH), 3.78 (s, 3 H, CH3), 3.70 (s, 3 H, CH3), 3.67 (s, 6 H, 2
CH3), 3.63 (s, 3 H, CH3).
13C NMR (50 MHz, CDCl3): d = 159.7, 159.6, 159.5, 159.3, 142.9,
137.3, 135.8, 135.2, 134.2, 133.9, 133.6, 131.8, 129.7, 129.4, 129.3,
129.1, 125.5, 125.1, 124.6, 123.3, 123.1, 118.0, 117.6, 116.9, 115.7,
115.5, 114.4, 114.2, 114.1, 113.7, 113.4, 55.3, 55.2.
Yield: 209 mg (67%).
MS (EI, 70 eV): m/z (%) = 624 [M+] (80).
Anal. Calcd for C34H56S5: C, 65.32; H, 9.03. Found: C, 64.97; H,
9.34.
MS (EI, 70 eV): m/z (%) = 609 [M+ – MeOC6H4S] (66), 470 [M+ –
1,1,2,4,4-Pentakis(benzylsulfanyl)buta-1,3-diene (4f)
NaNH2 (0.156 g, 4 mmol) was added to anhyd MeCN (15 mL) at r.t.
and BnSH (0.49 g, 4 mmol) was added in one portion. The mixture
was then stirred for 3 h. The precipitate was collected by filtration,
washed several times with anhyd Et2O under N2, and dried in vacuo.
This salt was then dissolved in DMSO (10 mL) and added to a soln
of 2 (0.454 g, 0.5 mmol). H2O (10 mL) was added, and then the
product was extracted with CH2Cl2 (3 × 35 mL). The organic layers
were combined, dried (MgSO4), and evaporated, and the resulting
residue was subjected to column chromatography (silica gel, PE–
EtOAc, 15:1); this gave a yellow oil.
2MeOC6H4S] (43), 326 (17).
Anal. Calcd for C39H36S5: C, 62.87, H, 4.87. Found: C, 63.05; H,
4.47.
2,3-Dichloro-1,1,4,4-tetrakis(4-pyridylsulfanyl)buta-1,3-diene
(5a)
A soln of the salt 2 (0.454 g, 0.5 mmol) was added dropwise to a
soln of NaOMe (0.22 g, 4 mmol) and pyridine-4-thiol (0.44 g, 4
mmol) in DMSO (10 mL). The mixture was then stirred for 2 h at
r.t. CH2Cl2 (3 × 35 mL) was used for extraction, and the organic lay-
ers were combined, dried (MgSO4), and concentrated to give a dark
oil. Column chromatography (silica gel, PE–EtOAc, 2:1) afforded
the product as a yellow oil.
Yield: 262 mg (79%).
IR (NaCl, thin film): 3060, 3027, 2920, 1601, 1494, 1236, 766 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.34–7.08 (m, 25 H, Ph), 5.73 (s,
1 H, =CH), 4.05 (s, 2 H, CH2), 3.91 (s, 2 H, CH2), 3.82 (s, 2 H, CH2),
3.78 (s, 2 H, CH2), 3.28 (s, 2 H, CH2).
Yield: 184 mg (66%).
IR (NaCl, thin film): 3406, 3034, 1660, 1568, 1405, 803 cm–1.
13C NMR (50 MHz, CDCl3): d = 143.2, 138.1, 137.9, 137.8, 137.7,
137.3, 136.2, 130.5, 130.2, 129.3, 129.1, 129.04, 129.01, 128.8,
128.6, 128.5, 128.4, 128.3, 127.7, 127.3, 127.2, 127.0, 126.9, 126.8,
39.1, 38.6, 38.1, 37.9, 37.4.
1H NMR (200 MHz, CDCl3): d = 8.55 (dd, J = 4.5, 1.6 Hz, 4 H),
8.49 (dd, J = 4.5, 1.6 Hz, 4 H), 7.36 (dd, J = 4.5, 1.6 Hz, 4 H), 7.25
(dd, J = 4.5, 1.6 Hz, 4 H).
13C NMR (50 MHz, CDCl3): d = 150.4, 149.9, 146.4, 145.7, 138.7,
124.7, 124.1, 120.8.
MS (EI, 70 eV): m/z (%) = 573 [M+ – benzyl] (65), 451 (36).
ESI-MS: m/z (%) = 480 [M+ – pyridine] (100), 481 (25), 482 (65).
Anal. Calcd for C39H36S5: C, 70.44; H, 5.46. Found: C, 70.21; H,
5.72.
Anal. Calcd for C24H16Cl2N4S4: C, 51.51; H, 2.88; N, 10.01. Found:
C, 52.08; H, 2.36; N, 9.74.
1,1,2,4,4-Pentakis(phenylsulfanyl)buta-1,3-diene (4g)
This compound has been mentioned before in the literature, but was
not characterized completely.24
S,S¢,S¢¢,S¢¢¢-2,3-Dichlorobuta-1,3-diene-1,1,4,4-tetrayl Tetra-
ethanethioate (5b)
NaNH2 (0.156 g, 4 mmol) was dissolved in anhyd MeCN (15 mL)
at r.t. and AcSH (0.3 g, 4 mmol) was added in a single portion. The
Synthesis 2009, No. 14, 2371–2378 © Thieme Stuttgart · New York

PAPER
Sulfanyl-Substituted [3]Cumulenes and Buta-1,3-dienes
2377
mixture was stirred for 3 h. The precipitate was collected by filtra-
tion, washed several times with anhyd Et2O under N2, and dried in
vacuo. This salt was then dissolved in DMSO (10 mL) and added to
a soln of 2 (0.454 g, 0.5 mmol) and subsequently stirred at 80 °C for
1 h. The product was then extracted with CH2Cl2, and the organic
layers were combined and dried (MgSO4). Finally, the solvent was
evaporated and the resulting residue was subjected to column chro-
matography (silica gel, PE–EtOAc, 3:1) to give a red solid.
2,3-Dichloro-1,1,4,4-tetrakis[(1-methyl-1H-imidazol-2-yl)sulfa-
nyl]buta-1,3-diene (5e)
NaNH2 (0.156 g, 4 mmol) was dissolved in anhyd MeCN (15 mL)
at r.t. and 1-methylimidazole-2-thiol (0.459 g, 4 mmol) was added
in one portion. The mixture was then stirred for 4 h, before the pre-
cipitate was collected by filtration, washed several times with anhyd
Et2O under an inert atmosphere, and dried in vacuo. A portion of
this salt (0.41 g, 3 mmol) was then dissolved in anhyd DMSO (20
mL) and added to a soln of 2 (0.454 g, 0.5 mmol). The mixture was
stirred at 60 °C for 3 h under N2, before it was filtered through silica
gel. The product was finally extracted with CH2Cl2 (3 × 40 mL),
and the organic layers were combined and dried (MgSO4). The sol-
vent was evaporated and the residue was subjected to column chro-
matography (silica gel, PE–EtOAc, 1:1); this gave a yellow solid.
Yield: 107 mg (51%); mp 61–63 °C.
IR (KBr): 2907, 1698, 1567, 1434 cm–1.
1H NMR (200 MHz, CDCl3): d = 2.52 (s, 6 H, CH3), 2.51 (s, 6 H,
CH3).
13C NMR (50 MHz, CDCl3): d = 191.2, 191.1, 138.2, 117.8, 31.6,
31.5.
MS (EI, 70 eV): m/z (%) = 418 [M+] (91).
Yield: 151 mg (53%); mp 137–140 °C.
IR (KBr): 3160, 3108, 1572, 1466, 1276 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.03 (d, J = 2.3 Hz, 2 H), 6.97 (d,
J = 2.3 Hz, 2 H), 6.90 (d, J = 2.3 Hz, 2 H), 6.84 (d, J = 2.3 Hz, 2 H),
3.65 (s, 6 H, CH3), 3.55 (s, 6 H, CH3).
Anal. Calcd for C12H12Cl2O4S4: C, 34.37; H, 2.88. Found: C, 34.21;
H, 2.72.
13C NMR (50 MHz, CDCl3): d = 160.3, 160.2, 123.4, 121.2, 121.1,
117.4, 115.2, 115.1, 34.6, 34.5.
2,3-Dichlorobuta-1,3-diene-1,1,4,4-tetrayl Tetrakis(diethylcar-
bamodithioate) (5c)
A soln of sodium diethylcarbamodithioate (0.67 g, 3 mmol) in
DMSO (10 mL) was added to a soln of the salt 2 (0.454 g, 0.5
mmol). The mixture was then stirred at r.t. for 3 h, and subsequently
filtered through silica gel. The product was extracted with CH2Cl2
(3 × 35 mL), and the organic layers were combined and dried
(MgSO4). Finally, the solvent was evaporated to give a residue,
which was subjected to column chromatography (silica gel, PE–
EtOAc, 5:1); this gave yellow needles.
MS (EI, 70 eV): m/z (%) = 570 [M+] (57).
Anal. Calcd for C20H20Cl2N8S4: C, 42.03; H, 3.53, N, 19.60. Found:
C, 42.51; H, 3.34; N, 19.21.
2,3-Dichloro-1,1,4,4-tetratosylbuta-1,3-diene (6)
A soln of sodium toluene-4-sulfinate (0.54 g, 3 mmol) in DMSO (10
mL) was added to a soln of the salt 2 (0.454 g, 0.5 mmol). The mix-
ture was then stirred at 70 °C for 45 min. The reaction mixture was
filtered through silica gel, the product was extracted with CH2Cl2
(3 × 35 mL), and the organic layers were combined and dried
(MgSO4). Finally, the solvent was evaporated to give a residue
which was subjected to column chromatography (silica gel, PE–
EtOAc, 10:1); this gave a white solid.
Yield: 281 mg (79%); mp 52–53 C.
IR (KBr): 2874, 1702, 1534, 1422 cm–1.
1H NMR (200 MHz, CDCl3): d = 4.07–4.01 (m, 8 H), 1.50 (t, J = 5.5
Hz, 6 H), 1.32 (t, J = 5.5 Hz, 6 H).
13C NMR (50 MHz, CDCl3): d = 192.7 (overlapping signals), 138.4,
Yield: 266 mg (72%); mp 72–73 °C.
IR (KBr): 3042, 2915, 1590, 1488, 1323, 1291, 1139, 806 cm–1.
122.1, 52.1, 47.6, 13.6, 11.5.
MS (EI, 70 eV): m/z (%) = 566 [ M+ – 2 NEt2] (77).
1H NMR (200 MHz, CDCl3): d = 7.46 (d, J = 7.9 Hz, 4 H), 7.24 (d,
J = 7.9 Hz, 4 H), 7.20 (d, J = 7.9 Hz, 4 H), 7.14 (d, J = 7.9 Hz, 4 H),
2.42 (s, 6 H, CH3), 2.38 (s, 6 H, CH3).
Anal. Calcd for C24H40Cl2N4S8: C, 40.48; H, 5.66; N, 7.87. Found:
C, 40.91; H, 5.32; N, 7.33.
13C NMR (50 MHz, CDCl3): d = 144.6, 142.0, 140.4, 136.5, 130.2,
S,S¢,S¢¢,S¢¢¢-2,3-Dichlorobuta-1,3-diene-1,1,4,4-tetrayl
O,O¢,O¢¢,O¢¢¢-Tetraethyl Tetrakiscarbonodithioate (5d)
A soln of potassium O-ethylcarbonodithioate (0.3 g, 3 mmol) in
DMSO (10 mL) was added to a soln of the salt 2 (0.454 g, 0.5
mmol). The mixture was then stirred at 50 °C for 90 min, and sub-
sequently filtered through silica gel. The product was extracted with
CH2Cl2 (3 × 35 mL), and the organic layers were combined and
dried (MgSO4). Finally, the solvent was evaporated to give a residue
which was subjected to column chromatography (silica gel, PE–
EtOAc, 5:1); this gave a yellow oily solid.
129.3, 127.6, 124.6, 21.6, 21.5 (overlapped), 21.5 (overlapped).
ESI-MS: m/z = 581, 296.
Anal. Calcd for C32H28Cl2O8S4: C, 51.96; H, 3.82. Found: C, 52.41;
H, 3.43.
Acknowledgment
The Deutsche Forschungsgemeinschaft (DFG) is gratefully
acknowledged for financial support.
Yield: 202 mg (67%).
IR (NaCl, thin film): 2893, 1697, 1660, 1548, 1413 cm–1.
1H NMR (200 MHz, CDCl3): d = 4.64 (q, J = 6 Hz, 4 H), 4.33 (q,
J = 6 Hz, 4 H), 1.45–1.30 (m, 12 H).
13C NMR (50 MHz, CDCl3): d = 215.0, 214.7, 139.3, 118.6, 30.1,
29.6, 13.8, 13.4.
MS (EI, 70 eV): m/z (%) = 558 [M+ – OEt] (64).
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