Synthesis and electrochemical characterization of dipyrroles separated by diphenyleneoxide and diphenylenesulfide spacers via the Trofimov reaction

Article abstract of DOI:10.1016/j.tet.2005.05.088

4,4′-Bis[2-(1-vinylpyrrolyl)]diphenyloxide, 4,4′-bis(2- pyrrolyl)diphenylsulfide, 4-(2-pyrrolyl)-4′-[2-(1-vinylpyrrolyl)] diphenylsulfide and 4,4′-bis[2-(1-vinylpyrrolyl)]diphenylsulfide have been synthesized in a one-pot procedure from oximes of correspo

Full text of DOI:10.1016/j.tet.2005.05.088

Tetrahedron 61 (2005) 7756–7762
Synthesis and electrochemical characterization of dipyrroles
separated by diphenyleneoxide and diphenylenesulfide spacers via
the Trofimov reaction
a
Alexander M. Vasil’tsov,a Elena Yu. Schmidt,a Al’bina I. Mikhaleva,a, Nadezhda V. Zorina,
*
Alexey B. Zaitsev,a Olga V. Petrova,a Leonid B. Krivdin,a Konstantin B. Petrushenko,a
a
b
b
Igor’ A. Ushakov, Cristina Pozo-Gonzalo, Jose A. Pomposo and Hans-Jurgen Grande
b
´
¨
aA. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, 1 Favorsky Str., Irkutsk 664033,
Russian Federation
´ ´ ´ ´ ´
CIDETEC, Centro de Investigacion Tecnologica en Electroquımica, Paseo Miramon, 196, E-20009, San Sebastian, Spain
b
Received 11 March 2005; revised 11 May 2005; accepted 26 May 2005
Available online 22 June 2005
Abstract—4,40-Bis[2-(1-vinylpyrrolyl)]diphenyloxide, 4,40-bis(2-pyrrolyl)diphenylsulfide, 4-(2-pyrrolyl)-40-[2-(1-vinylpyrrolyl)]diphenyl-
sulfide and 4,40-bis[2-(1-vinylpyrrolyl)]diphenylsulfide have been synthesized in a one-pot procedure from oximes of corresponding
diacetylphenylenoxide and -sulfide through their reaction with acetylene in the MOH–DMSO systems (MZLi, K) at 80–130 8C under
pressure of 10–15 atm, thus illustrating applicability and general character of the reaction of synthesis of diverse dipyrrole–phenylene
assemblies and their N-vinyl derivatives. Two of the pipyrroles are promising for creating new conducting polymers with sulfur and oxygen
atoms in the conjugation chain and for the study of the influence of the diphenyleneheteroatom moiety on conductivity of final polymer
products. For the dipyrroles with the diphenyleneheteroatom moieties and 1,4-phenylene spacer the luminescence characteristics were
determined.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
2. Results and discussion
Conjugated multi-ring monomers terminated with electron-
rich heterocycles are electropolymerizable at lower poten-
tials and with a minimum of side reactions leading to
conjugated polymers with enhanced and better tunable
properties.1 In this connection a number of works were
devoted to construction of dipyrroles separated by con-
jugated chains.1–4 In spite of the fact that no general
approaches were developed for creating dipyrroles separ-
ated by spacers comprising heteroatoms, conjugated
polymers derived from such monomers might be of practical
value due to their enhanced properties (e.g., widely used
polyaniline5 or its conducting sulfur-containing analogs
with diphenylenesulfide bridges)6 as well as of theoretical
interest for study of the effects imposed by these atoms on
conductivity.
2.1. Synthesis of dipyrroles separated by diphenylene-
oxide and diphenylenesulfide spacers
Herein, we describe an approach to dipyrroles, separated by
diphenyleneoxide and diphenylenesulfide spacers, from
dioximes of the corresponding diacylaromatics: 4,40-
diacetyldiphenyloxide and 4,40-diacetyldiphenylsulfide via
the Trofimov reaction.7 Previously, this reaction was
successfully used for the synthesis of 1,4-bis[2-(1-vinyl-
pyrrolyl)]benzene from 1,4-diacetylbenzene dioxime.8
However, it was not clear how the longer aromatic spacers
with oxygen and sulfur bridges will influence the reaction
course.
The reaction of 4,40-diacetyldiphenyloxide dioxime (1) with
acetylene in KOH–DMSO system (120 8C, 1 h) afforded
the expected divinyldipyrrole 3 (yield 27%), while under
milder conditions (70 8C, 0.5 h) the intermediate bis(O-
vinyloxime) 2 (yield 15%) was the only isolable product
(Scheme 1).
Keywords: Dipyrroles; Diphenyleneoxide spacer; Diphenylenesulfide
spacer; Dioximes; Acetylene; Superbase; Electropolymerization;
Luminescence.
*
Corresponding author. Tel.: C7 3952 42 24 09/42 58 71; fax: C7 3952
41 93 46; e-mail: mikh@irioch.irk.ru
4,40-Diacetyldiphenylsulfide dioxime (4), has been prepared
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.05.088

A. M. Vasil’tsov et al. / Tetrahedron 61 (2005) 7756–7762
7757
Scheme 1.
by reacting the corresponding diketone with NH2OH$HCl
in pyridine (80 8C, 6 h) with 99% yield. Its reaction with
acetylene in the LiOH–DMSO superbasic system (130 8C,
3 h, initial acetylene pressure 15 atm) gave the expected
dipyrrole 5 (yield 8%) together with mono- (6) (yield 13%)
and divinyl (7) (yield 6%) derivatives. This result does not
correspond to those for all previously studied oximes, which
under similar conditions in the same system selectively
afford NH-pyrroles (Scheme 2).7,9
vinyl)dioxime 8, monopyrrole derivative 9 and dipyrrole 5
(12, 6, and 7% isolated yields, respectively) (Scheme 3).
To selectively prepare dipyrrole 5 we attempted the thermal
rearrangement of 8 and 9 in DMSO in a way similar to that
described by Schmidt et al.10 However, in this case the
rearrangement to dipyrrole 5 proceeded at higher tempera-
ture (130 8C, 0.5 h), whereas at 120 8C (as in Ref. 10) 8
transformed only to 9, but the latter failed to rearrange to 5.
The following rationalization of this peculiar fact seems to
be probable: the intermediate carbanion A (according to the
accepted mechanism of the Trofimov reaction7) in the case
of O-vinyloxime with the pyrrole moiety 9 is additionally
quenched with the acidic pyrrole protons, which are absent
in the bis(O-vinyl)dioxime 8, that is, its rearrangement
occurs under more aprotic conditions (Scheme 4).
In the KOH–DMSO system (110 8C, 1 h) under acetylene
pressure (initial pressure 15 atm) the only product was
divinyldipyrrole 7 (14% non-optimized yield), while under
atmospheric pressure (120 8C, 5 h) deoximation of 4 and
autocondensation of the carbonyl derivatives leading to
resinification prevailed and only traces of dipyrroles were
identified by 1H NMR spectroscopy in the reaction mixture.
A short contact of dioxime 4 with acetylene under pressure
(90 8C, 5 min, initial pressure 15 atm) led to bis(O-
This slows down the formation of the next intermediate
Scheme 2.
Scheme 3.
Scheme 4.

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A. M. Vasil’tsov et al. / Tetrahedron 61 (2005) 7756–7762
divinyl hydroxylamine B and hence, the proceeding steps
leading to the pyrrole ring construction.
caused by better internal conversion of excited states of 3
due to the decreased conjugation of oxygen with phenyl
rings facilitating its internal rotation as compared to sulfur.
2.2. Absorption and emission properties of dipyrroles
separated by diphenyleneoxide and diphenylenesulfide
spacers
In much the same way, a hindered internal rotation of 11 is
the reason for its high quantum yield (2.9). It is noteworthy
that both rotational conformations of 11 depicted in Figure 1
as cis and trans are essentially non-planar with the pyrrole
rings twisted out the benzene plane by ca. 448. In its turn, the
vinyl groups are twisted out the planes of the pyrrole rings
by ca. 178 in both conformations. Apparently, the non-
planarity of cis and trans conformations results in the
noticeable hindrance of p,p as well as p,p conjugation. The
energetic gap between cis and trans conformations is only
ca. 0.4 kcal/mol, which implies essential population of the
less stable cis form.
To estimate the role of the diphenyleneoxide and
diphenylenesulfide spacers in transmission of excitation
between pyrrole rings, we studied fluorescent properties of
divinylpyrroles 3 and 7 in comparison with related mono-(2-
phenylpyrrole 10a and 2-phenyl-1-vinylpyrrole 10b)9 and
dipyrrolic (4,40-bis[2-(1-vinylpyrrolyl)]benzene 11)8,9
systems (Table 1). The quantum yield of 10a was assigned
to 1.
Table 1. Fluorescent properties of pyrrolic compounds
Thus, a better electronic conductivity should be expected for
polymers containing diphenylenesulfide and 1,4-phenylene
spacers as compared to those with diphenyleneoxide
spacers.
Compound
Absorbance, lmax, nm
Fluorescence, lmax, nm
(quantum yield relative to
10a)
n-C6H14
MeCN
n-C6H14
MeCN
3
7
10a
10b
11
283
304
289
270
307
287
304
287
267
309
350 (0.3)
363 (1.1)
322 (1.0)
344 (0.7)
378 (2.9)
364 (0.05)
(!0.01)
350 (2.0)
350 (0.2)
383 (2.4)
The observed dramatic decrease of fluorescence quantum
yields of 3 and 7 in acetonitrile solutions might be rendered
by quenching of their polar excited states (charge transfer
involving heteroatoms) by dipolar molecules of the solvent.
2.3. Electrochemistry of dipyrroles separated by
diphenyleneoxide and diphenylenesulfide spacers
The redox behavior of compounds 3, 7 and 11 were first
characterized by cyclic voltammetry, using acetonitrile as
the solvent and lithium perchlorate as the supporting
electrolyte. For the N-vinyl pyrrole derivative 3 and 7 one
irreversible oxidation wave was observed at C1.22 and
C1.08 V, respectively. The derivative 11 exhibited two
irreversible oxidation processes at C0.97 and C1.26 V
(Table 2), which could be attributed to the oxidation of the
The essential decrease of fluorescence quantum yield on
passing from 7 (1.1) to 3 (0.3) in n-hexane is probably
Figure 1. Rotational conformations of 1,4-bis[2-(1-vinylpyrrolyl)]benzene (11) optimized at the DFT-B3LYP/6-311G* level. Relative energies are given in
parentheses.
Table 2. UV and electrochemical data for compounds 3, 7, and 11
Compound
E1oxa (V)
E2oxa (V)
1rda (V)
lmax (nm)b
3
7
11
C1.22c
C1.08c
C0.97c
C0.60c
K0.87c
K0.66c
K1.60c
284
305
310
482
C1.26c
Poly(11)
a In acetonitrile.
b In dichloromethane.
c Irreversible peak.

A. M. Vasil’tsov et al. / Tetrahedron 61 (2005) 7756–7762
7759
Scheme 5. Resonance structures of the radical cation of 11.
pyrrole systems. It is noteworthy that the monomer
N-vinylpyrrole has an oxidation potential of C0.6 V
under similar conditions.11 It was assumed that an increase
in the degree of delocalization in poly(11) in comparison
with the monomer would take place and therefore, a lowest
oxidation process for poly(11) was expected. The disruption
of the planarity within the aromatic systems could play an
important role for an increase of the oxidation potential in
the system and it has been supported by theoretical
calculations. The derivative 11 exhibited the lowest
oxidation potential in the series, probably due to a higher
degree of electron delocalization in comparison with 3 and
7.
polymerization to take place. The corresponding voltammo-
gram is shown in Figure 2, which illustrates the
electrodeposition of the polymer using dry acetonitrile as
solvent. The formation of a new oxidation process around
C0.7 V indicates the formation of the new polymer and its
electroactivity on the working electrode. Figure 3 displays
the voltammogram for the poly(11) in a monomer free
solution. The polymer was completely dedoped before
oxidation or reduction process to eliminate possible charge
trapping during the experiment. Poly(11) exhibited one
oxidation process at C0.60 V exemplifying that the
polymer is a better electron donor than the monomer. The
stability for the polymer to both different scans and even
scan rate was not completely successful; therefore, we can
say that the polymer derived from 11 is not as stable as
expected. The absorption maxima for poly(11) was red-
shifted by more than 100 nm confirming the increase in
conjugation length (Table 2, Fig. 4) of the polymer in
It follows that the presence of the heteroatom (O and S,
respectively), in the derivatives 3 and 7 could produce a p
electron transmission blockage preventing the second
oxidation process within the pyrrole ring. On the other
hand, the value for the first oxidation process is quite high,
therefore, the conditions for the second oxidation process
are not favorable. The high degree of electron delocalization
in derivative 11 could be the reason for the second oxidation
process to take place. The possible resonance mechanisms
for 11, 3 and 7 are depicted in Schemes 5 and 6.
2.4. Electropolymerization of dipyrroles separated by
diphenyleneoxide and diphenylenesulfide spacers
Electropolymerization experiments were carried out for all
derivatives 3, 7, and 11 (acetonitrile, 10K3 M substrate,
0.1 M LiClO4, Ag/AgCl reference electrode), by repetitive
scanning over the first oxidation wave at scan rate of 50 mV/s,
using ITO glass or Pt as working electrode. Although, the
electrodeposition experiments were carried out for all of
them, only the derivative 11 succeeded in the electro-
polymerization process. The reason could be due to a
favorable spin density distribution in the radical cation for
Figure 2. Electrodeposition of 11 on Pt electrode in acetonitrile (Ag/AgCl
as reference electrode, Pt as auxiliary electrode, 0.1 M LiClO4 as
supporting electrolyte, scan rate 50 mV/s).
Figure 3. Cyclic voltammogram of poly(11) in a monomer-free acetonitrile
solution as a thin film on Pt working electrode (Ag/AgCl as reference
electrode, Pt as auxiliary electrode, 0.1 M LiClO4 as supporting electrolyte,
scan rate 50 mV/s).
Scheme 6. The blockage of the radical cation redistribution in 3 and 7.

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A. M. Vasil’tsov et al. / Tetrahedron 61 (2005) 7756–7762
Commercial grade DMSO (Merck, !0.2% H2O), LiOH
(!2% H2O), KOH (w15% H2O, in fact 2KOH$H2O) and
4,40-diacetyldiphenyloxide dioxime 1 were used in experi-
ments. For the preparation of 4,40-diacetyldiphenylsulfide,
see the Supplementary data.19
4.2. 4,40-Bis(O-vinyloxime) of 4,40-diacetyldiphenyloxide
(2) and bis[2-(1-vinylpyrrolyl)]diphenyloxide (3)
Method A. A mixture of 1 (3.0 g, 10.6 mmol), KOH$0.5
H2O (1.37 g, 21.1 mmol) and DMSO (50 mL) was saturated
with acetylene at room temperature (initial pressure 13 atm)
and heated at 70 8C for 0.5 h whilst rotating. Thereupon, it
was diluted with water up to 50 mL and extracted with ether
(5!10 mL). The ether extracts were washed with water
(3!10 mL), dried over K2CO3. The residue obtained after
evaporation of the ether was chromatographed on Al2O3
(hexane/ether 3:1) to give bis(O-vinyloxime) 2 (0.53 g,
15%).
Figure 4. Electronic absorption spectra of poly(11) on ITO glass.
comparison with the monomer, which is typical for
conducting polymers.12 The optical band-gap of poly(11)
can be obtained by UV/vis spectroscopy of ITO deposited
films and is estimated from the longest wavelength
absorption edge. The optical band-gap (Eg) value for such
a polymer is 1.5 eV, which is somehow lower than that
corresponding to the polypyrrole (3.2 eV).13 The difference
between the onset potentials for the reduction and oxidation
processes represents the electrochemical band-gap (Eg),
corresponding to the removal of electrons from the HOMO
band and injection of electrons into the LUMO band. The
electrochemical band-gap for poly(11) was 1.6 eV, which is
in good agreement with the optical band-gap.
Method B. The above mixture was saturated with acetylene
and heated at 120 8C for 1 h whilst rotating. After the
separation described bis(N-vinylpyrrole) 3 (1.0 g, 27%) was
obtained.
4.2.1. Compound 2. White crystals, mp 32–34 8C. 1H NMR
(CDCl3) d (ppm) 7.66 (d, 4H, Ho, 3Jo–mZ8.8 Hz), 7.01 (m,
3
2
6H, HX, Hm), 4.67 (dd, 2H, HB, JBXZ14.3 Hz, JAB
Z
3. Conclusions
3
2
1.2 Hz), 4.16 (dd, 2H, HA, JAXZ7.8 Hz, JABZ1.2 Hz),
2.30 (s, 6H, Me). 13C NMR (CDCl3) d (ppm) 158.2 (Cp),
156.6 (C]N), 152.8 (Ca), 131.2 (Ci), 128.2 (Co), 118.9
(Cm), 88.2 (Cb), 13.4 (Me). IR (cmK1, KBr): 3126, 3082,
3046, 3002, 2930, 2859, 1682, 1638, 1609, 1594, 1501,
1437, 1409, 1370, 1317, 1243, 1149, 1111, 1078, 1004, 970,
950, 885, 834, 761, 719, 699, 610, 593, 557, 493, 431. Anal.
Calcd for C20H20N2O3: C, 71.41; H, 5.99; N, 8.33. Found:
C, 71.44; H, 6.21; N, 8.63.
In conclusion, a novel approach to dipyrroles with
diphenyleneoxide and diphenylenesulfide spacers based on
the Trofimov reaction was developed. The prepared
dipyrroles are promising for creating new conducting
polymers with sulfur and oxygen atoms in the conjugation
chain and for the study of the influence of the diphenylene-
heteroatom moiety on conductivity of final polymer
products. Poly(11) has been successfully prepared via
electrochemical polymerization on Pt and ITO electrodes.
Attempts to obtain the electrochemically generated poly-
mers of 3 and 7 failed, which is due to unfavorable spin
density distribution in the radical cations. The above
dipyrroles possess the practically prospective luminescence
properties, thus confirming the expectations.
4.2.2. Compound 3. White crystals, mp 89–90 8C. 1H NMR
(CDCl3) d (ppm) 7.34 (d, 4H, Ho, Jo–m 8.8 Hz), 7.09 (m,
3
2H, H5), 7.06 (d, 4H, Hm, 3Jo–mZ8.8 Hz), 6.88 (dd, 2H, HX,
3
3JBXZ15.8 Hz, JAXZ8.9 Hz), 6.24 (m, 4H, H3, H4), 5.18
3
2
(dd, 2H, HB, JBXZ15.8 Hz, JABZ1.2 Hz), 4.70 dd (2H,
3
2
HA, JAXZ8.9 Hz, JABZ1.2 Hz). 13C NMR (CDCl3) d
(ppm) 156.5 (Cp), 133.7 (C2), 132.0 (Ca), 130.9 (Cm), 127.8
(Ci), 118.9 (Co), 118.2 (C5), 110.1, 109.9 (C3, C4), 98.9 (Cb).
IR (cmK1, KBr): 3140, 3095, 3051, 3004, 1643, 1609, 1598,
1573, 1546, 1496, 1467, 1425, 1348, 1312, 1279, 1232,
1179, 1168, 1100, 1075, 1030, 1013, 974, 950, 871, 860,
837, 819, 802, 786, 737, 717, 696, 668, 594, 569, 510. Anal.
Calcd for C24H20N2O: C, 81.79; H, 5.72; N, 7.95. Found: C,
81.41; H, 5.89; N, 7.69.
4. Experimental
4.1. General
1H (400.13 MHz) and 13C (101.61 MHz) NMR spectra were
recorded on a Bruker DPX 400 spectrometer with HMDS as
an internal standard. IR spectra were obtained on a Bruker
IFS 25 instrument. Spectrophotometric and fluorimetric
measurements were carried out on a UV/vis Lambda 25
instrument and the luminescence experimental setup.14
Geometrical optimizations were performed with GAMESS
code,15 at the DFT-B3LYP level (Becke’s three-parameter
hybrid functional16 where non-local correlation is provided
by Lee, Yang, and Parr correlation functional)17 with the
6-311G* basis set of Pople and co-workers.18 In all
calculations no symmetry constraints were applied (C1
symmetry point group was used throughout).
4.3. 4,40-Diacetyldiphenylsulfide dioxime (4)
A
mixture of 4,40-diacetyldiphenylsulfide (3.9 g,
14.4 mmol), NH2OH$HCl (2.9 g, 41.7 mmol) and pyridine
(30 mL) was stirred for 6 h at 80 8C, thereupon, it was
cooled and poured into cold water (150 mL). The precipitate
was filtered, washed with water and dried to afford dioxime
4 (4.3 g, 99%).
1
4.3.1. Compound 4. White powder, mp 188–190 8C. H

A. M. Vasil’tsov et al. / Tetrahedron 61 (2005) 7756–7762
7761
NMR (DMSO-d6) d (ppm) 10.00 (s, 2H, OH), 7.65 (d, 4H,
1565, 1516, 1491, 1461, 1424, 1348, 1316, 1297, 1266,
1240, 1195, 1180, 1123, 1086, 1075, 1032, 1014, 973, 949,
916, 875, 835, 821, 798, 716, 675, 593, 573, 538. Anal.
Calcd for C22H18N2S: C, 77.16; H, 5.30; N, 8.18; S, 9.36.
Found: C, 77.35; H, 5.41; N, 8.19; S, 8.97.
3
3
Ho, Jo–mZ7.7 Hz), 7.33 (d, 4H, Hm, Jo–mZ7.7 Hz), 2.13
(s, 6H, Me). 13C NMR (DMSO-d6) d (ppm) 152.3 (C]N),
136.1, 135.0 (Ci, Cp), 130.6, 126.7 (Co, Cm), 11.4 (Me). IR
(cmK1, KBr): 3307, 3242, 3091–2927, 1648, 1589, 1551,
1491, 1440, 1393, 1370, 1315, 1270, 1187, 1128, 1112,
1030, 1097, 1072, 1019, 1008, 934, 825, 785, 751, 716, 703,
567, 557, 515, 501, 487, 449, 434. Anal. Calcd for
C16H16N2O2S (%): C, 63.98; H, 5.37; N, 9.33; S, 10.67.
Found (%): C, 63.83; H, 5.47; N, 9.27; S, 11.20.
1
4.4.3. Compound 7. Beige crystals, mp 102–106 8C. H
3
NMR (CDCl3) d 7.34 (d, 4H, Ho, Jo–mZ8.5 Hz), 7.27 (d,
3
3
4H, Hm, Jo–mZ8.5 Hz), 7.11 (dd, 2H, H5, J4–5Z2.7 Hz,
4J3–5Z1.7 Hz), 6.84 (dd, 2H, HX, JBXZ15.7 Hz, JAX
8.7 Hz), 6.24 (m, 4H, H3, H4), 5.18 (dd, 2H, HB, JBX
Z
Z
3
3
3
2
3
4.4. 4,40-Bis(2-pyrrolyl)diphenylsulfide (5), 4-(2-pyrro-
lyl)-40-[2-(1-vinylpyrrolyl)]diphenylsulfide (6) and 4,40-
bis[2-(1-vinylpyrrolyl)]diphenylsulfide (7)
15.7 Hz, JABZ1.2 Hz), 4.70 dd (2H, HA, JAXZ8.7 Hz,
2JABZ1.2 Hz). 13C NMR (CDCl3) d 134.4, 133.3, 131.3 (Ci,
Cp, C2), 131.8 (Ca), 130.9, 129.7 (Co, Cm), 118.8 (C5),
110.4, 110.3 (C3, C4), 99.2 (Cb). IR (cmK1, KBr): 3133,
3106, 3075, 3026, 3002, 2929 (]CH), 1641, 1594, 1552,
1489, 1462, 1415, 1349, 1316, 1290, 1238, 1181, 1107,
1085, 1074, 1013, 974, 950, 880, 869, 829, 796, 729, 714,
674, 595, 574, 533, 517, 493. Anal. Calcd for C24H20N2S
(%): C, 78.23; H, 5.47; N, 7.60; S, 8.70. Found (%): C,
78.18; H, 5.62; N, 7.25; S, 8.71.
Method A. A mixture of dioxime 4 (2.00 g, 6.7 mmol),
LiOH (0.32 g, 13.3 mmol) and DMSO (75 mL) was
saturated with acetylene at room temperature (initial
pressure 10 atm) and heated at 130 8C for 3 h whilst
rotating. Thereupon, it was diluted with water up to
150 mL and extracted with ether (5!30 mL). The ether
extracts were washed with water (3!30 mL), dried over
K2CO3 and evaporated to afford deep-brown residue
(1.51 g), which was then extracted with a hexane/ether
mixture 1:1. Insoluble part was filtered out, washed out with
the same mixture of solvents and dried to afford dipyrrole 5
(0.16 g, 8%). The soluble part was chromatographed on
Al2O3 (hexane/ether 3:1) to give monovinyldipyrrole 6
(0.29 g, 13%) and divinylpyrrole 7 (0.14 g, 6%).
4.5. 4,40-Bis(vinyloximinoethyl)diphenylsulfide (8) and
4-(1-vinyloximinoethyl)-40-(2-pyrrolyl)diphenylsulfide
(9)
A mixture of 4 (0.60 g, 2 mmol), KOH$0.5 H2O (0.26 g,
4 mmol) and DMSO (20 mL) was saturated with acetylene
at room temperature (initial pressure 12 atm) and heated at
90 8C for 5 min whilst rotating. Thereupon, it was diluted
with water up to 50 mL and extracted with ether (5!
10 mL). The ether extracts were washed with water (3!
10 mL), dried over K2CO3. The residue obtained after
evaporation of the ether was chromatographed on Al2O3
(hexane/ether 3:1) to give bis(O-vinyl)dioxime 8 (0.085 g,
12%), monopyrrole derivative 9 (0.040 g, 6%) and dipyrrole
5 (0.045 g, 7%).
Method B. A mixture of 4 (0.60 g, 2 mmol), KOH$0.5 H2O
(0.26 g, 4 mmol) and DMSO (20 mL) was saturated with
acetylene at room temperature (initial pressure 15 atm) and
heated at 110 8C for 1 h whilst rotating. Thereupon, it was
diluted with water up to 50 mL and extracted with ether
(5!10 mL). The ether extracts were washed with water
(3!10 mL) and dried over K2CO3. The residue obtained after
evaporation of the ether was chromatographed on Al2O3
(hexane/ether 3:1) to give divinyldipyrrole 7 (0.10 g, 14%).
4.5.1. Compound 8. White crystals, mp 60–62 8C. 1H NMR
3
(CDCl3) d (ppm) 7.61 (d, 4H, Ho, Jo–mZ8.1 Hz), 7.33 (d,
4.4.1. Compound 5. Light-brown crystals, mp 123–126 8C.
1H NMR (DMSO-d6) d (ppm) 11.36 (broad s, 2H, NH), 7.61
4H, Hm, 3Jo–mZ8.1 Hz), 7.02 (dd, 2H, HX, 3JBXZ14.3 Hz,
3
2
3JAXZ7.8 Hz), 4.68 (dd, 2H, HB, JBXZ14.3 Hz, JAB
Z
3
3
3
2
(d, 4H, Ho, Jo–mZ8.5 Hz), 7.30 (d, 4H, Jo–mZ8.5 Hz),
6.86 (m, 2H, H5), 6.53 (m), 6.11 (m, 4H, H3, H4). 13C NMR
(DMSO-d6) d (ppm) 132.6, 131.7, 130.7 (Ci, Cp, C2), 131.6,
1.2 Hz), 4.18 (dd, 2H, HA, JAXZ7.8 Hz, JABZ1.2 Hz),
2.29 (s, 6H, Me). 13C NMR (CDCl3) d (ppm) 156.5 (C]N),
152.8 (Ca), 137.3, 134.6 (Ci, Cp), 130.9, 127.2 (Co, Cm),
88.4 (Cb), 13.2 (Me). IR (cmK1, KBr): 3122, 3075, 2923,
2857, 1673, 1641, 1607, 1489, 1458, 1391, 1371, 1317,
1270, 1170, 1128, 1110, 1094, 1071, 1004, 972, 945, 887,
837, 783, 727, 714, 680, 573, 556, 507, 475, 426, 411. Anal.
Calcd for C20H20N2O2S: C, 68.16; H, 5.72; N, 7.95; S, 9.10.
Found: C 68.33, H, 5.65; N, 7.71; S, 8.57.
124.7 (Co, Cm), 120.2 (C5), 109.7, 106.6 (C3, C4). IR (cmK1
,
KBr): 3438, 3391, 1668, 1638, 1596, 1491, 1452, 1426,
1297, 1243, 1189, 1114, 1032, 915, 880, 826, 799, 723, 543.
Anal. Calcd for C20H16N2S: C, 75.92; H, 5.10; N, 8.85; S,
10.13. Found: C, 76.22; H, 5.00; N, 9.20; S, 9.94.
1
4.4.2. Compound 6. Beige crystals, mp 112–115 8C. H
NMR (DMSO-d6) d (ppm) 10.45 (broad s, 1H, NH), 7.57
1
4.5.2. Compound 9. Cream crystals, mp 138–142 8C. H
0
0
(m, 2H, Hm ), 7.42 (m, 2H, Ho ), 7.27 (s, 4H, Ho, Hm), 7.10
NMR (CDCl3) d (ppm) 8.45 (br s, 1H, NH), 7.59 (d), 7.43
0
3
3
3
0
0
(m, 1H, H5 ), 6.85 (dd, 1H, HX, JBXZ15.6 Hz, JAX
Z
(d), 7.37 (d), 7.24 (d, 8H, Ho, Hm, Ho , Hm , Jo–mZ8.5 Hz,
3
3
Jo –m Z4.5 Hz), 7.02 (dd, 1H, HX, JBXZ14.2 Hz, 3JAX
7.8 Hz), 6.87 (m, 2H, H5), 6.54 (m), 6.30 (m, 4H, H3, H4),
Z
0
0
8.8 Hz), 6.83 (m, 1H, H5), 6.51 (m, 1H, H3), 6.24 (m, 3H,
0
3
2
0
H3 , H4, H4 ), 5.19 (dd, 1H, HB, JBXZ15.6 Hz, JAB
Z
3
2
1.0 Hz), 4.72 (dd, 1H, HA, JAXZ8.8 Hz, JABZ1.0 Hz).
0
C NMR (DMSO-d6) d (ppm) 135.8 (Ci ), 133.1 (C2 ),
132.5 (Cm, Ci), 131.5 (Ca), 130.8 (C2), 130.3 (Cp), 130.1
0
(Cp ), 129.3, 129.1 (Co , Cm ), 124.3 (Co), 119.3 (C5), 118.3
4.68 (dd, 1H, HB, 3JBXZ14.2 Hz, 2JABZ1.2 Hz), 4.17 (dd,
13
3
2
0
1H, HA, JAXZ7.8 Hz, JABZ1.2 Hz), 2.27 (s, 3H, Me).
13C NMR (CDCl3) d 156.7 (C]N), 152.8 (Ca), 139.4,
133.8, 133.3, 132.5, 131.3, 131.2, 129.2, 127.0, 124.6 (Ci,
0
0
0
0
0
0
0
0
0
(C5 ), 107.4 (C3 , C4 ), 109.3 (C4), 105.9 (C5), 98.9 (Cb). IR
(cmK1, KBr): 3434, 3143, 3102, 3055, 1675, 1642, 1595,
Ci , Co, Co , Cm, Cm , Cp, Cp , C2), 119.5 (C5), 110.5, 106.8
(C3, C4), 88.3 (Cb), 13.2 (Me). IR (cmK1, KBr): 3435, 3137,

7762
A. M. Vasil’tsov et al. / Tetrahedron 61 (2005) 7756–7762
Kartritzky, A. R., Ed.; Academic: San Diego, 1990; Vol. 51,
pp 177–301. (b) Bean, G. P. The Synthesis of 1H-Pyrroles.
Part 1. Pyrroles. In The Synthesis and the Chemical and the
Physical Aspects Pyrrole Ring; Jones, R. A., Ed.; Wiley: New
York, 1992; p 105. (c) Trofimov, B. A. Vinylpyrroles In The
Chemistry of Heterocyclic Compounds. Part 2; Jones, R. A.,
Ed.; Wiley: New York, 1992; Vol. 48, pp 131–298. (d)
Tedeschi, R. J. Acetylene; In Encyclopedia of Physical
Science and Technology; Academic: San Diego, 1992; Vol.
1; pp 27–65 (e) Gossauer, A. Pyrrole; In Georg Thieme:
Stuttgart, 1994; Methoden Der Organischen Chemie. Hetarene
I. Teil 1; pp 556–798. (f) Mikhaleva, A. I.; Schmidt, E. Yu.
Two-step Synthesis of Pyrroles from Ketones and Acetylenes
through the Trofimov Reaction. In Selected Methods for
Synthesis and Modification of Heterocycles; Kartsev, V. G.,
Ed.; IBS: Moscow, 2002; Vol. 1, 331–352.
3106, 3072, 2932, 2857, 1637, 1603, 1558, 1506, 1490,
1454, 1430, 1416, 1397, 1367, 1318, 1172, 1130, 1099,
1067, 1036, 1006, 975, 952, 917, 886, 838, 821, 799, 730,
668, 549, 477, 411. Anal. Calcd for C20H18N2OS: C, 71.83;
H, 5.42; N, 8.38; S, 9.59. Found: C, 71.69; H, 5.23; N, 8.51;
S, 9.69.
Acknowledgements
This work was supported by the Russian Foundation for
Basic Research (grants no. 03-03-32472 and no.
2241.2003.3) and the Presidium of the Russian Academy
of Sciences (grant no. 10002-251/P-25/155-305/200404-
072).
8. Korostova, S. E.; Mikhaleva, A. I. Zh. Org. Khim. 1982, 18,
2620–2621.
Supplementary data
9. Trofimov, B. A.; Mikhaleva, A. I. N-Vinylpyrroles; Nauka:
Novosibirsk, 1984; p 264, in Russian.
10. Schmidt, E. Yu.; Zorina, N. V.; Zaitsev, A. B.; Mikhaleva,
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.tet.2005.05.
088.
´
A. I.; Vasil’tsov, A. M.; Audebert, P.; Clavier, G.; Meallet-
Renault, R.; Pansu, R. B. Tetrahedron Lett. 2004, 45,
5489–5491.
´ ˇ
11. Hlavaty, J.; Papez, V.; Kavan, L.; Krtil, P. Synth. Met. 1994,
66, 165–168.
12. Chapman, G. M.; Stanforth, S. P.; Berridge, R.; Pozo-Gonzalo,
C.; Skabara, P. J. J. Mater. Chem. 2002, 12, 2292–2298.
13. Abdou, M. S. A.; Holdcroft, S. In Handbook of Organic
Conductive Molecules and Polymers; Nawa, H. S., Ed.; Wiley:
New York, 1997; p 613.
References and notes
1. Soloducho, J. Synth. Met. 1999, 99, 181–189.
2. Eldo, J.; Arunkumar, E.; Ajayaghosh, A. Tetrahedron Lett.
2000, 41, 6241–6244.
14. Petrushenko, K. B.; Klyba, L. V.; Smirnov, V. I.; Shevchenko,
S. G. Russ. Chem. Bull. 2001, 50, 798–804.
3. Soloducho, J.; Doskocz, J.; Cabaj, J.; Roszak, S. Tetrahedron
2003, 59, 4761–4766.
15. Schmidt, M. W.; Baldridge, K. K.; Boatz, J. A.; Elbert, S. T.;
Gordon, M. S.; Jensen, J. H.; Koseki, S.; Matsunaga, N.;
Nguyen, K. A.; Su, S. J.; Windus, T. L.; Dupuis, M.;
Montgomery, J. A. J. Comp. Chem. 1993, 14, 1347–1363.
16. Becke, A. D. J. Chem. Phys. 1993, 98, 5648–5652.
17. Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B 1988, 37, 785–789.
18. Krisnan, R.; Binkley, J. S.; Seeger, R.; Pople, J. A. J. Chem.
Phys. 1980, 72, 650–654.
4. Aldakov, D.; Anzenbacher, P., Jr. Chem. Commun. 2003,
1394–1395.
5. Handbook of Conducting Polymers; Skotheim, T. A.,
Elsenbaumer, R. L., Reynolds, J. R., Eds.; Marcel Dekker:
New York/Basel/Hong Kong, 1998.
6. Zhu, K.; Wang, L.; Jing, X.; Wang, F. J. Mater. Chem. 2002,
12, 181–187.
19. Supplementary Material is available on the Elsevier site http://
www.elsevier.com.
7. (a) Trofimov, B. A. Preparation of Pyrroles from Ketoximes
and Acetylenes. In Advances in Heterocyclic Chemistry;