New applications of hetaryl thioketones for the synthesis of hetaryl-substituted ethenes via 'two-fold extrusion reaction'

Article abstract of DOI:10.3987/COM-15-S(T)8

A series of aryl/hetaryl thioketones was applied for the reactions with aryl/hetaryldiazomethanes yielding, after elimination of N₂, the corresponding thiiranes. The relatively unstable dihetaryldiazomethanes were generated in situ from the corresponding hydrazones by oxidation with DMSO. The obtained thiiranes were converted into tetraaryl/hetaryl-substituted ethenes in good yields by desulfurization performed with tris(diethylamino)phosphine ((Et₂N)₃P).

Full text of DOI:10.3987/COM-15-S(T)8

HETEROCYCLES, Vol. 93, No. 1, 2016, pp. -. © 2016 The Japan Institute of Heterocyclic Chemistry
Received, 24th July, 2015, Accepted, 2nd September, 2015, Published online, 6th October, 2015
DOI: 10.3987/COM-15-S(T)8
NEW APPLICATIONS OF HETARYL THIOKETONES FOR THE
SYNTHESIS OF HETARYL-SUBSTITUTED ETHENES VIA ‘TWO-FOLD
EXTRUSION REACTION’
Grzegorz Mlostoń,a* Katarzyna Urbaniak,a Aneta Pawlak,a and Heinz
Heimgartnerb*
a: Department of Organic and Applied Chemistry, University of Łódź, Tamka 12,
PL-91-403 Łódź, Poland; e-mail: gmloston@uni.lodz.pl
b: Department of Chemistry, University of Zurich, Winterthurerstrasse 190,
CH-8057 Zurich, Switzerland; e-mail: heinz.heimgartner@chem.uzh.ch
Dedicated to Professor Dr. Lutz F. Tietze, University of Göttingen (Germany), on
the occasion of his 75th birthday
Abstract – A series of aryl/hetaryl thioketones was applied for the reactions with
aryl/hetaryldiazomethanes yielding, after elimination of N2, the corresponding
thiiranes. The relatively unstable dihetaryldiazomethanes were generated in situ
from the corresponding hydrazones by oxidation with DMSO. The obtained
thiiranes were converted into tetraaryl/hetaryl-substituted ethenes in good yields
by desulfurization performed with tris(diethylamino)phosphine ((Et2N)3P).
INTRODUCTION
Hetaryl-substituted ethenes constitute a class of organic compounds with great importance for
applications in materials chemistry. The most relevant usage relates to their optoelectronic properties and
crystal engineering.1 They also display unique electrochemical properties, and as electron donors they
were used for the synthesis of stable dications.2 In addition, they are precursors of polyaromatic
heterocycles, which can be prepared via photochemically induced oxidative cyclizations.3
The synthesis of symmetrical aryl/hetaryl-substituted ethenes is based on the McMurry protocol, in which
the corresponding aryl/hetaryl ketones are treated with TiCl4, Zn dust, and pyridine in boiling THF.3,4

Recently, another method was reported, in which non-symmetrical ethenes are accessible. In that case, an
aryl/hetaryl ketone is initially converted to the corresponding gem-dibromoethene, which subsequently
undergoes reaction with arene/hetarene via Suzuki-Stille coupling, leading to tetraaryl/hetaryl-substituted
ethenes in decent yields.1
Another well-known method for the synthesis of differently substituted ethenes is the desulfurization of
thiiranes, which in turn can easily be prepared according to the Eschenmoser protocol (Eschenmoser
sulfide contraction)5 or by treatment of thioketones with the corresponding diazo compounds. In the latter
case, diaryl thioketones react with diaryldiazomethanes with spontaneous elimination of N2 to give
thiiranes as exclusive products.6 The subsequent desulfurization can be efficiently achieved using
P(III)-compounds such as Ph3P or (Et2N)3P. This stepwise procedure is known as ‘two-fold extrusion
reaction’.6a,7
In a recent publication we described a convenient method for the preparation of diaryl/hetaryl thioketones
containing furan-2-yl, thiophen-2-yl, or selenophen-2-yl substituents.8 They were shown to react
vigorously with diazomethane even at low temperature affording 4,4,5,5-tetrasubstituted 1,3-dithiolanes
via a proposed diradical mechanism.8,9
The goal of the present study was the examination of the reaction of aryl/hetaryl thioketones with
aryl/hetaryldiazomethanes as a possible route to tetraaryl/hetaryl thiiranes, which subsequently could be
desulfurized to yield the corresponding tetrasubstituted ethene derivatives.
RESULTS AND DISCUSSION
The reactions of aryl/hetaryl thioketones 1a-f with aryl/hetaryldiazomethanes 2a-d were performed at
–60 °C to room temperature over night. Whereas diphenyldiazomethane (2a) and diazofluorenone (2b)
can be prepared, stored, and used in syntheses, the hitherto unknown (phenylthiophen-2-yl)diazomethane
(2c) and di(thiophen-2-yl)diazomethane (2d) were prepared in situ and used without isolation, because
they decompose rapidly at room temperature. The disappearance of the characteristic color of the
thioketones 1 was observed between –40 and –30 °C, accompanied with the evolution of N2. The crude
mixtures were purified by column chromatography (SiO2) leading to a single product in each case. The
structures of the expected thiiranes 5 (Scheme, Table) were proved on the basis of their spectroscopic data
13
and elemental analyses. For example, in the C-NMR spectrum of 5a, the characteristic signals of C(2)
and C(3) were observed at 62.3 and 67.3 ppm, and in the case of 5d the analogous signals appeared at
56.0 and 69.0 ppm. In the symmetrical tetra(thiophen-2-yl)thiirane (5k), the signal for C(2) and C(3) was
found at 57.8 ppm. The formation of 1,2-diphenyl-1,2-di(thiophen-2-yl)thiirane (5i) occurred with low
selectivity leading to a ca. 1:1.3-mixture of two stereoisomers (cis/trans), which could not be separated by
column chromatography.

N
N
Ar1
Ar3
Ar1
Ar2
N N
THF or Et2O
-60 °C
-N2
Ar1
Ar2
Ar3
Ar4
+
Ar2
S
Ar4
-40 to -30 °C
S
S
Ar3
Ar4
4a-n
3a-n
1a-f
2a-d
Ar1
Ar2
Ar4
Ar3
Ar1
Ar2
Ar4
Ar3
(Et2N)3P
THF, rt
S
6a-n
5a-n
Scheme
Table. Synthesis of thiiranes 5 and ethene derivatives 6a)
1
Ar1
Ar2
2
Ar3
Ar4
5
Yield (%)b)
6
Yield (%)c)
a
b
c
d
e
f
Ph
Thi
Sel
Fur
Thi
Sel
Thi
Thi
Sel
Thi
Thi
Thi
Sel
Thi
Sel
a
a
a
a
a
a
b
b
c
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
a
b
c
d
e
f
44.6
42.0
45.6
57.2
-
a10
b
c
56.0
36.8
74.0
68.8
71.0d)
76.8
61.6
65.0
86.1f)
23.4
Ph
Fur
Thi
Sel
Fur
Ph
d3
e
48.0
67.4
41.4
46.0e)
35.1
11.6
56.2
72.4
68.9
f
a
b
a
a
d
e
f
g
h
i
g
Ph
h
i4
j
Ph
Thi
Thi
Thi
Thi
Thi
Thi
Ph
Ph
d
d
d
d
c
j
Thi
Thi
Thi
Thi
Ph
g
Thi
Sel
Fur
Sel
k
l
k
l
)
37.6
73.5
68.9
m
n
m
n
e
a) For reaction conditions see Scheme; Abbreviations: Ph = Phenyl, Fur = Furan-2-yl, Thi =
Thiophen-2-yl, Sel = Selenophen-2-yl. b) With respect to starting thioketone 1. c) With respect to thiirane
d
5. ) With respect to thioketone 1e. ) Cis/trans-mixture (ca. 1:1). ) (Z/E)-mixture (ca. 1:1.3). ) Not
e
f
g
prepared (see ref. [2a]).

In general, the thiiranes 5 are fairly stable compounds, which were isolated in ca. 40 – 70% yield. Only in
the case of 2,2-diphenyl-3,3-di(selenophen-2-yl)thiirane (5e), the crude product was identified as a
mixture of 5e and the corresponding ethene 6e, which apparently was formed via spontaneous extrusion
of sulfur. The chromatographic separation of both compounds was unsuccessful, and for that reason, the
crude product was desulfurized by treatment with (Et2N)3P in THF solution. The analogous method was
applied for the removal of the S-atom from thiiranes 5 to give the corresponding ethenes 6 in yields up to
86% (Scheme, Table). Their structures were confirmed by spectroscopic data and elemental analyses. The
desulfurization of the cis/trans-mixture of 5i gave a mixture of the (Z/E)-isomers of
1,2-diphenyl-1,2-di(thiophen-2-yl)ethene (6i).
The mechanism of the reaction of thioketones 1 with diazo compounds 2 is presented in the Scheme and
corresponds to the interpretation of the so-called ‘Schönberg reaction’.11 The diaryldiazomethane 2 reacts
as a 1,3-dipole with the C=S group as the dipolarophile in a [3+2] cycloaddition to yield the unstable
2,2,5,5-tetraaryl-2,5-dihydro-1,3,4-thiadiazole 3, which easily eliminates N2 even below 0 °C. The
intermediate thiocarbonyl ylide 4 undergoes a 1,3-dipolar electrocyclization to give thiirane 5 as the
exclusive product. It is well known that the reactive tetraaryl-substituted thiocarbonyl ylides do not
undergo the competitive reactions leading to other products like 1,4-dithianes (dimerization) or
1,3-dithiolanes ([3+2] cycloadditions with starting thioketones).
CONCLUSIONS
The present study showed that the easily accessible aryl/hetaryl thioketones react smoothly with
aryl/hetaryldiazomethanes and, after spontaneous elimination of N2, the corresponding thiiranes are
obtained as products of the 1,3-dipolar electrocyclization of the intermediate reactive thiocarbonyl ylides.
In general, the thiiranes are stable compounds and can be isolated as pure substances. The subsequent
desulfurization can be efficiently achieved by their treatment with tris(diethylamino)phosphine. This
method, corresponding to the ‘two-fold extrusion’ protocol, is performed without any metal catalyst and
can be considered as an attractive alternative approach to polyhetaryl-substituted ethenes. Moreover, in
contrast to the McMurry approach, it allows the preparation of non-symmetrical ethene derivatives, and
the substitution pattern can be designed by the selection of the aryl/hetaryl thioketone and the aryl/hetaryl-
diazomethane.
EXPERIMENTAL
General remarks. Melting points were determined in a capillary using a Melt-Temp. II (Aldrich)
apparatus, and they are uncorrected. The IR spectra were recorded on a NEXUS FT-IR spectrophotometer
1
13
in KBr; absorptions in cm–1. The H- and C{1H}-NMR spectra were measured on a Bruker Avance III

instrument (600 and 150 MHz, resp.) using solvent signals as reference. Chemical shifts (δ) are given in
ppm and coupling constants J in Hz. ESI-MS and CI-MS were recorded on a Varian 500-MS LC IonTrap
spectrometer in the Laboratory of Mass Spectrometry of the University of Łódź; the HR-ESI-MS for 6j
was recorded on a Bruker maxis spectrometer in the Laboratory of Mass Spectrometry of the University
of Zurich. Elemental analyses were performed in the Laboratory of the Faculty of Chemistry (University
of Łódź).
Starting materials. Hetaryl thioketones 1 were obtained in a typical manner from the corresponding
ketones and Lawessonʼs reagent in boiling toluene or benzene.12 Aromatic and heteroaromatic hydrazones,
as starting materials for the preparation of the aryl/hetaryldiazomethanes, were prepared from the
corresponding ketones by treatment with excess hydrazine hydrate in EtOH according to the published
procedure for benzophenone hydrazone.13 Diphenyldiazomethane (2a) was prepared and separated as a
red oil that solidified on cooling according to the described procedure via dehydrogenation of hydrazones
with activated DMSO in the presence of Et3N.14 Heteroaromatic diazo compounds were prepared in situ
according to the same procedure. 9-Diazofluorene15 was obtained in a typical manner from corresponding
hydrazone and yellow mercury oxide.
General procedure for the reaction of hetaryl thioketones 1 with in situ generated diazo compounds
2. A solution of 1 mmol of the corresponding thioketone 1 in 1 mL of dry Et2O was cooled in a
acetone/dry ice bath to –60 °C. The mixture was treated with a cooled solution containing excess of the
corresponding freshly prepared diazo compound 2. The mixture was stirred magnetically and allowed to
warm to room temperature. Change of the color of the solution was observed at ca. –40 to –30 °C
depending on the used thioketone 1. The solvent was evaporated and the residue was purified
chromatographically (SiO2) using mixtures of hexane and CH2Cl2 as eluent. The obtained products were
additionally purified by crystallization from hexane or petroleum ether containing a small amount of
CH2Cl2.
2-(2,3,3-Triphenylthiiran-2-yl)thiophene (5a). Yield: 165 mg (44.6%). Mp 158.5–162.3 °C (hexane).
1H-NMR: 6.55 (dd, JH,H = 3.7, 1.3 Hz, 1CHarom); 6.67 (dd, JH,H = 5.2, 3.8 Hz, 1CHarom); 6.97–6.99 (m,
4CHarom); 7.12–7.13 (m, 5CHarom); 7.20–7.21 (m, 3CHarom); 7.33–7.34 (m, 2CHarom); 7.39–7.41 (m,
2CHarom). 13C-NMR: 62.3, 67.3 (2Cq); 126.1, 126.4, 126.7, 127.0, 127.1, 127.2, 127.3, 127.4, 128.6, 129.8,
130.9, 131.4 (12 signals for 18CHarom); 139.7, 139.8, 140.4, 148.5 (4Carom). IR (KBr): 3057m, 3024m,
1600m, 1492s, 1444s, 1234s, 1077m, 833m, 750s, 697vs, 637m. CI-MS: 394 ([M+1+Na]+, 18), 371
([M+1]+, 27), 370 (M+, 13), 338 ([M–S]+, 25), 337 ([M–1–S]+, 100). Anal. Calcd for C24H18S2 (370.08): C

77.79, H 4.89, S 17.31. Found: C 78.07, H 4.87, S 17.28.
2,2,3-Triphenyl-3-(selenophen-2-yl)thiirane (5b). Yield: 175 mg (42.0%). Mp 146.9–149.3 °C
1
(hexane/CH2Cl2). H-NMR: 6.72 (d, JH,H = 3.8 Hz, 1CHarom); 6.96 (t, JH,H = 5.6 Hz, 1CHarom); 7.00–7.02
(m, 3CHarom); 7.16–7.17 (m, 5CHarom); 7.25–7.27 (m, 3CHarom); 7.37 (dd, JH,H = 5.7, 1.9 Hz, 2CHarom);
7.48–7.49 (m, 2CHarom); 7.74 (d, JH,H = 5.7 Hz, 1CHarom). 13C-NMR: 64.4, 67.5 (2Cq); 126.4, 126.7, 127.0,
127.1, 127.2, 127.3, 127.5, 127.6, 127.7, 129.2, 129.7, 130.4, 130.8, 131.3, 131.7, 132.3 (16 signals for
18CHarom); 139.7, 140.0, 140.4, 156.6 (4Carom). IR (KBr): 3049m, 3023m, 1599m, 1490s, 1444s, 1233s,
1079m, 1029m, 834m, 777s, 742s, 700vs, 688vs, 658m. CI-MS: 419 [(M+2)+, 100]], 418 [(M+1)+, 15],
417 (M+, 50)]. Anal. Calcd for C24H18SSe (417.42): C 69.06, H 4.35, S 7.68. Found: C 69.36, H 4.33, S
7.57.
2-[2-(2-Furyl)-3,3-diphenylthiiran-2-yl]furan (5c). Yield: 157 mg (45.6%). Mp 128.6–130.8 °C
(hexane/CH2Cl2). 1H-NMR: 6.06 (dd, JH,H = 3.4, 1.0 Hz, 2CHarom); 6.16 (dd, JH,H = 3.4, 1.9 Hz, 2CHarom);
13
7.14–7.18 (m, 6CHarom); 7.25 (dd, JH,H = 1.9, 1.0 Hz, 2CHarom); 7.38–7.40 (m, 4CHarom). C-NMR: 49.9,
67.1 (2Cq); 110.3, 111.0, 127.0, 127.5, 129.5, 142.3 (6 signals for 16CHarom); 140.4, 151.2 (2 signals for
4Carom). IR (KBr): 3083m, 3057m, 3030m, 1598m, 1585m, 1489s, 1445s, 1221m, 1198m, 1149s, 1081m,
1066m, 1013vs, 930m, 852m, 817m, 741vs, 701vs, 647m. CI-MS: 367 (25, [M+Na]+), 345 (73, [M+1]+),
344 (52, M+), 312 (29, [M–S]+), 311 (100, [M–1–S]+). Anal. Calcd for C22H16O2S (344.43): C 76.72, H
4.68, S 9.31. Found: C 76.70, H 4.70, S 9.25.
2-[3,3-Diphenyl-2-(2-thienyl)thiiran-2-yl]thiophene (5d). Yield: 215 mg (57.2%). Mp 148.5–150.1 °C
(petroleum ether). 1H-NMR: 6.74 (dd, JH,H = 5.0, 3.5 Hz, 2CHarom); 6.82 (dd, JH,H = 3.6, 1.2 Hz, 2CHarom);
13
7.07 (dd, JH,H = 5.0, 1.2 Hz, 2CHarom); 7.13–7.18 (m, 6CHarom); 7.35–7.38 (m, 4CHarom). C-NMR: 56.0,
69.0 (2Cq); 125.8, 126.1, 127.0, 127.3, 128.9, 130.3 (6 signals for 16CHarom); 139.9, 145.8 (2 signals for
4Carom). IR (KBr): 3080m, 3059m, 3028m, 1599m, 1490s, 1444s, 1232m, 1080m, 1066m, 1033m, 854m,
822m, 752m, 697vs, 647m. Anal. Calcd for C22H16S3 (376.56): C 70.17, H 4.28, S 25.55. Found: C 69.95,
H 4.39, S 25.01.
2,2-Diphenyl-3,3-di(selenophen-2-yl)thiirane (5e). This product was detected in the crude reaction
mixture together with 6e and, without separation, was converted directly into alkene derivative 6e.
1H-NMR: 7.76 (d, JH,H = 1.3 Hz, 1CHarom), 7.78 (d, JH,H = 1.3 Hz, 1CHarom).
2-[3,3-Diphenyl-2-(2-thienyl)thiiran-2-yl]furan (5f). Yield: 173 mg (48.0%). Mp 126.4–128.3 °C

1
(petroleum ether/CH2Cl2). H-NMR: 6.03 (d, JH,H = 3.2 Hz, 1CHarom); 6.13 (dd, JH,H = 3.2, 1.9 Hz,
1CHarom); 6.78 (dd, JH,H = 5.0, 3.6 Hz, 1CHarom); 6.99 (dd, JH,H = 3.6, 1.0 Hz, 1CHarom); 7.05 (dd, JH,H
=
13
5.0, 1.0 Hz, 1CHarom); 7.12–7.18 (m, 6CHarom); 7.30 (brs, 1CHarom); 7.38–7.41 (m, 4CHarom). C-NMR:
52.9, 68.9 (2Cq); 110.2, 110.9, 125.9, 126.4, 126.9, 127.0, 127.4, 127.8, 128.8, 129.5, 130.2, 142.3 (12
signals for 16CHarom); 140.0, 140.6, 143.5, 152.7 (4Carom). IR (KBr): 3082m, 3029m, 2999m, 2958m,
1596m, 1489s, 1445s, 1372m, 1233m, 1149s, 1070m, 1033m, 1010s, 944m, 850m, 813m, 787m, 735vs,
700vs, 648m. CI-MS: 383 (100, [M+Na]+), 360 (17, M+), 359 (39, [M–1]+). Anal. Calcd for C22H16OS2
(360.49): C 73.30, H 4.47, S 17.79. Found: C 73.04, H 4.51, S 17.42.
3'-Phenyl-3'-(2-thienyl)spiro[fluorene-9,2'-thiirane] (5g). Yield: 248 mg (67.4%). Mp 136.2–138.2 °C
1
(hexane/CH2Cl2). H-NMR: 6.15 (d, JH,H = 7.7 Hz, 1CHarom); 6.64 (d, JH,H = 7.7 Hz, 1CHarom); 6.85–6.89
(m, 2CHarom); 7.00 (t, JH,H = 7.6 Hz, 1CHarom); 7.08 (d, JH,H = 3.5 Hz, 1CHarom); 7.16 (d, JH,H = 5.00 Hz,
1CHarom); 7.23 (brs, 3CHarom); 7.28–7.31 (m, 2CHarom); 7.36 (t, JH,H = 7.5 Hz, 2CHarom); 7.75 (d, JH,H = 7.6
13
Hz, 1CHarom); 7.77 (d, JH,H = 7.6 Hz, 1CHarom). C-NMR: 59.3, 59.6 (2Cq); 119.6, 119.7, 124.8, 125.6,
125.9, 126.2, 126.3, 126.6, 127.5, 127.9, 128.1, 128.4 (12 signals for 16CHarom); 141.0, 141.1, 142.1,
142.6, 142.7, 147.1 (6Carom). IR (KBr): 3061m, 3021m, 1578m, 1488m, 1447s, 1347m, 1299m, 1155m,
1076m, 1026m, 868m, 735vs, 697vs, 654m. Anal. Calcd for C24H16S2 (368.51): C 78.22, H 4.38, S 17.40.
Found: C 78.02, H 4.51, S 16.96.
3'-Phenyl-3'-(selenophen-2-yl)spiro[fluorene-9,2'-thiirane] (5h). Yield: 172 mg (41.4%). Mp
1
144.8–147.7 °C (hexane/CH2Cl2). H-NMR: 6.12 (d, JH,H = 7.8 Hz, 1CHarom); 6.77 (d, JH,H = 7.8 Hz,
1CHarom); 6.84 (t, JH,H = 7.6 Hz 1CHarom); 6.99 (t, JH,H = 7.6 Hz 1CHarom); 7.06–7.08 (m, 1CHarom);
7.19–7.21 (m, 2CHarom); 7.24–7.27 (m, 4CHarom); 7.32 (t, JH,H = 7.4 Hz, 2CHarom); 7.70 (d, JH,H = 7.6 Hz,
1CHarom); 7.73 (d, JH,H = 7.6 Hz, 1CHarom); 7.84 (d, JH,H = 5.6 Hz, 1CHarom). 13C-NMR: 59.8, 61.6 (2Cq);
119.6, 119.7, 125.2, 126.0, 126.3, 126.6, 127.5, 128.1, 128.4, 128.5, 130.0, 131.9 (12 signals for
16CHarom); 141.0, 141.2, 142.4, 142.6, 142.7, 154.6 (6Carom). IR (KBr): 3051m, 3019m, 1578m, 1488m,
1447s, 1155m, 1108m, 1004m, 834m, 728vs, 690s, 653m. Anal. Calcd for C24H16SSe (415.41): C 69.36,
H 3.88, S 7.72. Found: C 69.20, H 3.90, S 7.69.
2-[2,3-Diphenyl-3-(2-thienyl)thiiran-2-yl]thiophene (5i; mixture of cis/trans-isomers). Yield: 173 mg
1
(46.0%). Mp 178.5–180.7 °C (hexane). H-NMR: 6.54 (dd, JH,H = 3.6, 1.1 Hz, 1CHarom); 6.66 (dd, JH,H
=
5.2, 3.6 Hz, 1CHarom); 6.81–6.84 (m, 2CHarom); 6.98 (dd, JH,H = 5.1, 1.2 Hz, 1CHarom); 7.08–7.11 (m,
3CHarom); 7.16 (dd, JH,H = 5.1, 1.4 Hz, 1CHarom); 7.27–7.31 (m, 5CHarom); 7.51–7.53 (m, 2CHarom).
13C-NMR: 62.4, 62.9 (2Cq); 126.1, 126.3, 126.4, 127.2, 127.4, 127.5, 127.6, 128.5, 129.1, 130.1, 130.8

(12 signals for 16CHarom); 139.3, 139.9, 146.4, 147.9 (4Carom). IR (KBr): 3067m, 3024m, 1596m, 1490m,
1444s, 1428m, 1349m, 1231m, 1155m, 1076m, 1048m, 855m, 751s, 696vs, 614m. Anal. Calcd for
C22H16S3 (376.56): C 70.17, H 4.28, S 25.55. Found: C 69.86, H 4.21, S 25.74.
2-[2-Phenyl-3,3-bis(2-thienyl)thiiran-2-yl]thiophene (5j). Yield: 134 mg (35.1%). Mp 156.8–161.4 °C
(hexane/CH2Cl2). 1H-NMR: 6.64–6.66 (m, 3CHarom); 6.70 (dd, JH,H = 5.0, 3.7 Hz, 1CHarom); 6.83 (dd, JH,H
= 5.2, 3.7 Hz, 1CHarom); 6.96 (dd, JH,H = 4.8, 1.6 Hz, 1CHarom); 7.00 (dd, JH,H = 3.6, 1.3 Hz, 1CHarom); 7.04
13
(dd, JH,H = 5.0, 1.1 Hz, 1CHarom); 7.17–7.22 (m, 4CHarom); 7.41–7.43 (m, 2CHarom). C-NMR: 56.7, 64.0
(2Cq); 125.9, 126.0, 126.3, 126.4, 126.5, 126.6, 127.6, 128.5, 128.7, 129.5, 130.6 (11 signals for
14CHarom); 139.6, 144.2, 146.8, 147.1 (4Carom). IR (KBr): 3098m, 3061m, 3024m, 1597m, 1489m, 1443m,
1428m, 1350m, 1229s, 1174m, 1073m, 1048m, 833m, 753m, 702vs, 616m. Anal. Calcd for C20H14S4
(382.58): C 62.79, H 3.69, S 33.52. Found: C 62.37, H 3.78, S 33.40.
2-[2,3,3-Tris(2-thienyl)thiiran-2-yl]thiophene (5k). Yield: 45 mg (11.6%). Mp 150.9–153.2 °C
(hexane/CH2Cl2). 1H-NMR: 6.75 (dd, JH,H = 5.0, 3.6 Hz, 4CHarom); 6.86 (dd, JH,H = 3.6, 1.1 Hz, 4CHarom);
7.10 (dd, JH,H = 5.0, 1.1 Hz, 4CHarom). 13C-NMR: 57.8 (2Cq); 126.2, 129.0 (2 signals for 12CHarom); 144.9
(4Carom). IR (KBr): 3098m, 3061m, 1488m, 1426m, 1349m, 1232s, 1077m, 1046m, 1005m, 854m, 832m,
811m, 796m, 700vs, 618m. Anal. Calcd for C18H12S5 (388.61): C 55.63, H 3.11, S 41.26. Found: C 55.74,
H 3.31, S 41.31.
2-[3,3-Di(selenophen-2-yl)-2-(2-thienyl)thiiran-2-yl]thiophene (5l). Yield: 271 mg (56.2%). Mp
143.1–144.4 °C (petroleum ether/CH2Cl2). 1H-NMR: 6.79 (dd, JH,H = 5.2, 3.1 Hz, 2CHarom); 6.94 (dd, JH,H
= 3.7, 1.3 Hz, 2CHarom); 7.02 (dd, JH,H = 5.6, 3.7 Hz, 2CHarom); 7.09 (dd, JH,H = 3.7, 1.2 Hz, 2CHarom); 7.14
(dd, JH,H = 5.2, 1.1 Hz, 2CHarom); 7.83 (dd, JH,H = 5.6, 1.2 Hz, 2CHarom). 13C-NMR: 58.3, 62.0 (2Cq); 126.3,
128.8, 129.3, 131.3, 132.5 (5 signals for 12CHarom); 145.0, 152.4 (2 signals for 4Carom). IR (KBr): 3092m,
3077m, 1636m, 1445m, 1496m, 1430m, 1352m, 1235s, 1187m, 1122m, 1032s, 837m, 809m, 742vs, 691vs,
602m. Anal. Calcd for C18H12S3Se2 (482.40): C 44.82, H 2.51, S 19.94. Found: C 44.89, H 2.59, S 19.94.
2-[2,3,3-Tris(2-thienyl)thiiran-2-yl]furan (5m). Yield: 262 mg (72.4%). Mp 149.3–151.9 °C
(hexane/CH2Cl2). 1H-NMR: 6.16 (dd, JH,H = 3.1, 0.7 Hz, 1CHarom); 6.21 (dd, JH,H = 3.5, 1.9 Hz, 1CHarom);
6.78–6.83 (m, 3CHarom); 6.92–6.94 (m, 2CHarom); 7.00 (dd, JH,H = 3.6, 1.2 Hz, 1CHarom); 7.13–7.15 (m,
13
3CHarom); 7.32 (dd, JH,H = 1.9, 0.7 Hz, 1CHarom). C-NMR: 54.7, 56.8 (2Cq); 110.4, 111.0, 126.0, 126.1,
126.2, 126.3, 126.4, 126.5, 128.2, 129.0, 129.1, 142.5 (12CHarom); 142.7, 144.2, 145.0, 151.9 (4Carom). IR
(KBr): 3100m, 3063m, 1688m, 1608m, 1496m, 1428m, 1350m, 1232s, 1157m, 1139m, 1076m, 1041m,

1006m, 855s, 834m, 741s, 701vs, 613m. Anal. Calcd for C18H12OS4 (372.55): C 58.03, H 3.25, S 34.43.
Found: C 57.80, H 3.28, S 34.52.
2-[2-Phenyl-3,3-di(selenophen-2-yl)thiiran-2-yl]thiophene (5n). Yield: 328 mg (68.9%). Mp
162.4–164.1 °C (petroleum ether/CH2Cl2). 1H-NMR: 6.72–6.73 (m, 2CHarom); 6.89 (dd, JH,H = 4.0, 1.3 Hz,
1CHarom); 6.94 (dd, JH,H = 5.6, 4.0 Hz, 1CHarom); 7.08–7.11 (m 2CHarom); 7.22–7.27 (m, 4CHarom);
7.47–7.49 (m, 2CHarom); 7.72 (dd, JH,H = 5.6, 1.1 Hz, 1CHarom); 7.93 (dd, JH,H = 5.6, 1.1 Hz, 1CHarom).
13C-NMR: 60.8, 64.5 (2Cq); 126.6, 126.7, 127.6, 127.7, 128.4, 128.9, 129.1, 130.6, 130.7, 131.9, 132.1,
132.5 (12 signals for 14CHarom); 139.8, 147.1, 151.6, 156.6 (4Carom). IR (KBr): 3068m, 3027m, 1598m,
1489s, 1490m, 1443s, 1349m, 1230s, 1076m, 1032m, 841m, 805m, 751m, 688vs, 655m, 644m. Anal.
Calcd for C20H14S2Se2 (476.38): C 50.43, H 2.96, S 13.46. Found: C 50.12, H 3.05, S 13.59.
General procedure for the desulfurization of thiiranes 5. Desulfurization of thiiranes 5 by treatment
with tris(diethylamino)phosphine was performed according to a known procedure.16 A solution of 1 mmol
of thiirane 5 and 1 mmol (247 mg) tris(diethylamino)phosphine in dry THF (5 mL) was heated at reflux
for 1.5–2 h. After evaporation of the solvent, the crude mixture was purified chromatographically (SiO2),
using a 3:2-mixture of hexane and CH2Cl2. Products 6 were additionally purified by crystallization from
petroleum ether or hexane.
2-(1,2,2-Triphenylvinyl)thiophene (6a).10 Yield: 189 mg (56%). Mp 196.4–198.5 °C (hexane/CH2Cl2).
1H-NMR: 6.58 (dd, JH,H = 3.5, 1.1 Hz, 1CHarom); 6.77 (dd, JH,H = 5.2, 3.6 Hz, 1CHarom); 6.98–7.00 (m,
2CHarom); 7.04–7.07 (m, 3CHarom); 7.12 (dd, JH,H = 5.2, 1.1 Hz, 1CHarom); 7.14–7.19 (m, 5CHarom);
13
7.23–7.25 (m, 5CHarom). C-NMR: 126.0, 126.1, 126.4, 126.9, 127.0, 127.6, 127.7, 128.2, 129.5, 130.8,
130.9, 131.3 (12 signals for 18CHarom); 133.9, 141.2, 143.2, 143.6, 146.6 (4Carom, 2C=). IR (KBr): 3048m,
3018m, 1595m, 1571m, 1489s, 1442s, 1430m, 1255m, 1227m, 1183m, 1073m, 1027m, 855m, 827m,
700vs, 648m, 634m. Anal. Calcd for C24H18S (338.46): C 85.17, H 5.36, S 9.47. Found: C 84.93, H 5.31,
S 9.37.
1
2-(1,2,2-Triphenylvinyl)selenophene (6b). Yield: 142 mg (36.8%). Mp 142 °C (dec.). H-NMR: 6.76
(dd, JH,H = 3.8, 0.8 Hz, 1CHarom); 6.96–7.00 (m, 3CHarom); 7.04–7.07 (m, 3CHarom); 7.15–7.17 (m,
3CHarom); 7.20–7.22 (m, 2CHarom); 7.28–7.31 (m, 5CHarom); 7.84 (dd, JH,H = 5.6, 0.8 Hz, 1CHarom).
13C-NMR: 126.3, 126.9, 126.4, 127.4, 127.5, 127.7, 128.5, 128.6, 130.8, 131.0, 131.3, 132.1 (12 signals
for 18CHarom); 136.3, 140.7, 143.2, 143.3, 143.4, 152.3 (4Carom, 2C=). IR (KBr): 3074m, 3048m, 3017m,
1597m, 1574m, 1488s, 1443s, 1225m, 1227m, 1154m, 1074m, 1027m, 829m, 815m, 773vs, 735vs, 646m,

629m. Anal. Calcd for C24H18Se (385.36): C 74.80, H 4.71. Found: C 74.73, H 4.68.
2-[1-(2-Furyl)-2,2-diphenylvinyl]furan (6c). Yield: 231 mg (74.0%). Mp 140.1–142.3 °C (petroleum
1
ether/CH2Cl2). H-NMR: 6.07 (dd, JH,H = 3.4, 0.5 Hz, 2CHarom); 6.29 (dd, JH,H = 3.4, 1.9 Hz, 2CHarom);
13
7.09, 7.12 (2d, JH,H = 2.1 Hz, 4CHarom); 7.18–7.23 (m, 8CHarom). C-NMR: 111.0, 112.0, 127.1, 127.8,
130.2, 141.6 (6 signals for 16CHarom); 119.7, 142.0, 143.3, 153.3 (4 signals for 4Carom, 2C=). IR (KBr):
3077m, 3048m, 3032m, 1596m, 1575m, 1486s, 1442s, 1379m, 1304m, 1216s, 1159s, 1135s, 1072s,
1016vs, 976s, 933s, 886s, 819m, 742vs, 700vs, 633vs, 596vs. Anal. Calcd for C22H16O2 (312.36): C 84.59,
H 5.16. Found: C 84.40, H 5.09.
2-[2,2-Diphenyl-1-(2-thienyl)vinyl]thiophene (6d).3 Yield: 235 mg (68.3%). Mp 161.6–164 °C
(hexane/CH2Cl2). 1H-NMR: 6.77 (dd, JH,H = 3.7, 1.2 Hz, 2CHarom); 6.81 (dd, JH,H = 5.2, 3.7 Hz, 2CHarom);
13
7.15–7.22 (m, 12CHarom). C-NMR: 126.1, 126.3, 127.0, 128.0, 129.7, 130.6 (6 signals for 16CHarom);
126.6, 142.3, 143.2, 145.6 (4 signals for 4Carom, 2C=). IR (KBr): 3072m, 3052m, 3018m, 1594m, 1574m,
1488s, 1440s, 1421m, 1245s, 1228s, 1180m, 1153m, 1074s, 1027s, 999m, 854s, 832s, 696vs, 637s, 576s.
Anal. Calcd for C22H16S2 (344.49): C 76.70, H 4.68, S 18.62. Found: C 76.74, H 4.68, S 18.36.
2-[2,2-Diphenyl-1-(selenophen-2-yl)vinyl]selenophene (6e). Yield: 311 mg (71%). Mp 169.3–172.2 °C
1
(hexane/CH2Cl2). H-NMR: 7.04–7.09 (m, 4CHarom); 7.12–7.15 (m, 2CHarom); 7.21–7.25 (m, 8CHarom);
13
7.92 (d, JH,H = 1.3 Hz, 1CHarom); 7.93 (d, JH,H = 1.4 Hz, 1CHarom). C-NMR: 126.4, 127.1, 127.6, 128.1,
128.6, 130.8, 131.3, 132.1, 132.2 (9 signals for 16CHarom); 131.0, 141.0, 141.4, 143.2, 143.7, 152.0
(4Carom, 2C=). IR (KBr): 3080m, 3056m, 3026m, 1598m, 1489m, 1443s, 1225m, 1179m, 1079m, 1031m,
1001m, 838m, 821m, 751s, 692vs, 651s, 600m. Anal. Calcd for C22H16Se2 (438.28): C 60.29, H 3.68.
Found: C 60.26, H 3.69.
2-[2,2-Diphenyl-1-(2-thienyl)vinyl]furan (6f). Yield: 252 mg (76.8%). Mp 150.1–152.4 °C (hexane).
1H-NMR: 6.05 (d, JH,H = 3.2 Hz, 1CHarom); 6.28 (dd, JH,H = 3.2, 1.7 Hz, 1CHarom); 6.77 (dd, JH,H = 3.5, 0.9
Hz, 1CHarom); 6.82 (dd, JH,H = 5.0, 3.6 Hz, 1CHarom); 7.08–7.09 (m, 2CHarom); 7.18–7.24 (m, 10CHarom).
13C-NMR: 111.0, 112.1, 126.2, 126.3, 126.9, 127.1, 127.8, 128.0, 129.6, 129.9, 130.8, 141.6 (12 signals
for 16CHarom); 123.1, 142.3, 142.9, 143.4, 143.5, 154.8 (4Carom, 2C=). IR (KBr): 3074m, 3043m, 3020m,
1597m, 1573m, 1489s, 1441s, 1425m, 1353m, 1224s, 1157m, 1112m, 1018s, 932m, 854m, 815m, 754vs,
699vs, 625m. Anal. Calcd for C22H16OS (328.43): C 80.45, H 4.91, S 9.76. Found: C 80.23, H 4.79, S
9.66.

2-[Fluoren-9-ylidene(phenyl)methyl]thiophene (6g). Yield: 207 mg (61.6%). Mp 188.8–190.3 °C
1
(hexane/CH2Cl2). H-NMR: 6.59 (d, JH,H = 8.0 Hz, 1CHarom); 6.92 (dt, JH,H = 8.0, 1.1 Hz 1CHarom);
7.04–7.07 (m, 2CHarom); 7.13 (dd, JH,H = 5.5, 3.4 Hz, 1CHarom); 7.20 (dd, JH,H = 3.4, 1.1 Hz, 1CHarom);
7.24 (dt, JH,H = 7.4, 0.8 Hz, 1CHarom); 7.27–7.30 (m, 1CHarom); 7.44 (brs, 5CHarom); 7.49 (dd, JH,H = 5.0,
13
1.1 Hz, 1CHarom); 7.70 (t, JH,H = 8.0 Hz, 2CHarom). C-NMR: 119.2, 119.3, 124.8, 125.0, 126.5, 126.6,
127.5, 127.9, 128.0, 128.1, 128.6, 128.7, 128.8, 129.8 (14 signals for 16CHarom); 136.2, 137.3, 138.5,
138.6, 140.6, 140.7, 142.8, 144.9 (6Carom, 2C=). IR (KBr): 3054m, 3031m, 3019m, 1606m, 1565m, 1441s,
1339m, 1283m, 1218m, 1192m, 1155m, 1072m, 1027m, 985m, 917m, 866m, 852m, 779vs, 762vs, 731vs,
712vs, 697s, 653m. Anal. Calcd for C24H16S (336.45): C 85.68 H 4.79, S 9.53. Found: C 85.64, H 4.79, S
9.56.
2-[Fluoren-9-ylidene(phenyl)methyl]selenophene (6h): Yield: 249 mg (65.0%). Mp 190 °C (dec.)
(hexane/CH2Cl2). 1H-NMR: 6.58 (d, JH,H = 8.0 Hz, 1CHarom); 6.94 (t, JH,H = 8.0 Hz, 1CHarom); 7.08 (t, JH,H
= 8.0 Hz, 1CHarom); 7.25–7.29 (m, 2CHarom); 7.31 (dt, JH,H = 7.9, 0.8 Hz 1CHarom); 7.37 (dd, JH,H = 5.6, 3.6
Hz 1CHarom); 7.43 (dd, JH,H = 3.6, 1.1 Hz, 1CHarom); 7.47 (brs, 5CHarom); 7.72 (d, JH,H = 7.6 Hz, 1CHarom);
13
7.74 (d, JH,H = 7.6 Hz, 1CHarom); 8.24 (dd, JH,H = 5.6, 1.1 Hz, 1CHarom). C-NMR: 119.2, 119.3, 125.1,
125.2, 126.4, 126.6, 127.8, 127.9, 128.6, 128.8, 129.6, 129.9, 130.8, 134.1 (14 signals for 16CHarom);
135.3, 138.6, 138.7, 139.8, 140.6, 143.2, 151.7 (7 signals for 6Carom, 2C=). IR (KBr): 3056m, 3030m,
3017m, 1605m, 1562m, 1441s, 1426s, 1340m, 1260m, 1178m, 1109m, 1072m, 944m, 866m, 777vs, 757s,
697vs, 672m. Anal. Calcd for C24H16Se (383.34): C 75.20 H 4.21. Found: C 75.31, H 4.19.
2-[(1,2-Diphenyl-2-(2-thienyl)vinyl)thiophene (6i; mixture of (E/Z)-isomers).4 Yield: 298 mg (86.1%).
Mp 149.1–151.4 °C (hexane/CH2Cl2). 1H-NMR: 6.37 (dd, JH,H = 3.7, 1.1 Hz 1CHarom); 6.70 (dd, JH,H = 3.7,
1.3 Hz 1CHarom); 6.89 (dd, JH,H = 5.1, 3.6 Hz 1CHarom); 7.05 (dd, JH,H = 5.0, 1.1 Hz 1CHarom); 7.10 (brs,
13
6CHarom); 7.24–7.25 (m, 2CHarom); 7.38–7.40 (m, 4CHarom). C-NMR: 125.8, 126.5, 126.7, 126.8, 126.9,
127.6, 128.0, 128.8, 129.4, 129.7, 130.9, 131.0 (12 signals for 16CHarom); 133.1, 134.7, 142.3, 142.7,
145.8, 145.9 (4Carom, 2C=). IR (KBr): 3058m, 3023m, 2962m, 1596m, 1468m, 1442s, 1351m, 1261m,
1212m, 1155m, 1071m, 1056m, 856m, 852m, 811s, 744s, 724s, 695vs, 615m. Anal. Calcd for C22H16S2
(344.49): C 76.70 H 4.68, S 18.62. Found: C 76.60, H 4.79, S 18.62.
2-[1-Phenyl-2,2-bis(2-thienyl)vinyl]thiophene (6j). Yield: 82 mg (23.4%). Mp 168.8–171.3 °C
1
(hexane/CH2Cl2). H-NMR: 6.55 (dd, JH,H = 3.8, 1.1 Hz 1CHarom); 6.56 (dd, JH,H = 3.7, 1.1 Hz 1CHarom);
6.74 (dd, JH,H = 5.0, 3.7 Hz 1CHarom); 6.79 (dd, JH,H = 5.0, 3.7 Hz 1CHarom); 7.04–7.07 (m, 2CHarom); 7.09
(dd, JH,H = 5.1, 1.1 Hz 1CHarom); 7.19 (dd, JH,H = 5.1, 1.1 Hz 1CHarom); 7.32–7.37 (m, 5CHarom); 7.42 (dd,

JH,H = 3.7, 2.6 Hz 1CHarom). 13C-NMR: 125.9, 126.0, 126.8, 127.1, 127.3, 127.5, 128.0, 128.6, 129.6,
129.8, 130.0, 130.8 (12 signals for 14CHarom); 125.6, 135.6, 142.0, 142.7, 145.5, 145.6 (4Carom, 2C=). IR
(KBr): 3098m, 3060m, 1485m, 1440s, 1426s, 1351m, 1235m, 1204m, 1173m, 1096m, 1059m, 1024s, 849s,
852m, 729s, 695vs, 596m. ESI-MS: 352 (51, [M+2]+), 351 (100, [M+1]+), 350 (84, M+). HR-ESI-MS
(MeOH + NaI): 351.03304 (calcd 351.03301 for C20H15S3, [M+1]+).
2-[2,2-Di(selenophen-2-yl)-1-(2-thienyl)vinyl]thiophene (6l). Yield: 168 mg (37.6%). Mp
1
207.8–209.6 °C (hexane/CH2Cl2). H-NMR: 6.92 (d, JH,H = 1.3 Hz, 1CHarom); 6.93 (d, JH,H = 1.1 Hz,
1CHarom); 6.97 (d, JH,H = 3.7 Hz, 1CHarom); 6.98 (d, JH,H = 3.7 Hz, 1CHarom), 7.15 (d, JH,H = 1.1 Hz,
1CHarom); 7.16 (d, JH,H = 1.1 Hz, 1CHarom); 7.19 (d, JH,H = 3.8 Hz, 1CHarom); 7.20 (d, JH,H = 3.8 Hz,
1CHarom); 7.36 (dd, JH,H = 5.2, 1.3 Hz, 2CHarom); 8.06 (dd, JH,H = 5.6, 1.2 Hz, 2CHarom). 13C-NMR: 126.7,
128.0, 129.0, 130.4, 132.5, 133.6 (6 signals for 12CHarom); 126.7, 131.1, 144.0, 150.1 (4Carom, 2C=). IR
(KBr): 3091m, 3070m, 1450m, 1431s, 1344m, 1234s, 1189m, 1124m, 1070m, 1046s, 1008m, 846s, 799m,
760s, 709vs, 695vs, 640m, 589m. Anal. Calcd for C18H12S2Se2 (450.34): C 48.01, H 2.69, S 14.24. Found:
C 48.07, H 2.76, S 14.45.
2-[1,2,2-Tris(2-thienyl)vinyl]furan (6m). Yield: 250 mg (73.5%). Mp 155.2–157.0 °C (hexane/CH2Cl2).
1H-NMR: 6.16 (dd, JH,H = 3.3, 0.6 Hz 1CHarom); 6.39 (dd, JH,H = 3.3, 1.7 Hz 1CHarom); 6.85 (dd, JH,H = 3.7,
1.1 Hz 1CHarom); 6.90–6.95 (m, 6CHarom); 7.28–7.31 (m, 2CHarom); 7.33 (dd, JH,H = 1.7, 0.6 Hz 1CHarom).
13C-NMR: 111.5, 112.5, 126.5, 126.6, 126.8, 127.4, 127.6, 127.8, 128.9, 129.9, 130.1, 142.2, (12CHarom);
123.8, 129.5, 142.6, 144.3, 145.0, 153.7 (4Carom, 2C=). IR (KBr): IR (KBr): 3095m, 3080m, 1472m,
1432s, 1349m, 1245m, 1202m, 1159m, 1074m, 1059m, 1021m, 935m, 855s, 814m, 750s, 701vs, 596m.
Anal. Calcd for C18H12OS3 (340.48): C 63.50 H 3.55, S 28.25. Found: C 63.57, H 3.61, S 28.61.
2-[1-Phenyl-2,2-di(selenophen-2-yl)vinyl]thiophene (6n). Yield: 306 mg (68.9%). Mp 188.2–190.4 °C
1
(hexane/CH2Cl2). H-NMR: 6.55 (d, JH,H = 3.7 Hz, 1CHarom); 6.79–6.80 (m, 1CHarom); 6.89 (d, JH,H = 3.8
Hz, 1CHarom); 6.99 (dd, JH,H = 5.5, 3.8 Hz, 1CHarom); 7.20 (d, JH,H = 5.1 Hz, 1CHarom); 7.25 (d, JH,H = 5.3
Hz, 1CHarom); 7.29 (dd, JH,H = 5.5, 3.7 Hz, 1CHarom); 7.34–7.42 (m, 5CHarom); 7.82 (d, JH,H = 5.6 Hz,
13
1CHarom); 8.17 (d, JH,H = 5.6 Hz, 1CHarom). C-NMR: 125.9, 127.9, 128.3, 128.4, 129.0, 129.5, 130.4,
131.1, 132.2, 132.4, 132.9, 133.4 (12 signals for 14CHarom); 129.9, 134.6, 141.7, 145.5, 150.2, 150.9
(4Carom, 2C=). IR (KBr): 3094m, 3058m, 1483m, 1439s, 1345m, 1236s, 1199m, 1155m, 1061m, 1017m,
998m, 836m, 783m, 725s, 689vs, 639m, 614m. Anal. Calcd for C20H14SSe2 (444.31): C 54.06 H 3.18, S
7.22. Found: C 54.05, H 3.26, S 7.46.

ACKNOWLEDGEMENTS
The authors thank the National Science Center (PL-Cracow) for financial support within the project
Maestro (Grant Maestro-3; Dec-2012/06/A/ST5/00219).
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