Alkatrienyl sulfoxides and sulfones. Part I. 3-methyl-1,2,4-pentatrienyl phenyl sulfoxide-synthesis and electrophile-induced cyclization reactions

Article abstract of DOI:10.1080/10426500214293

A method for the synthesis of the 3-methyl-1,2,4-pentatrienyl phenyl sulfoxide 3 by [2,3]-sigmatropic rearrangement of the 3-methyl-1-penten-4-yn-3-yl benzenesulfenate 2, formed in the reaction of the 3-methyl-1-pentene-4-yn-2-ol 1 with phenylsulfenyl chloride has been created. Possibilities and restrictions of the five-membered heterocyclization in electrophile-induced reactions leading to the synthesis of the 5H-1,2-oxathiol-2-ium salts 5, 7, and 8 have been explored. Chlorination of the sulfoxide 2 proceeded with formation of the (E)-2-chloro-3-methylene-1,4-pentadienyl phenyl sulfoxide 4, while the bromination afforded the 4-bromo-5H-1,2-oxathiol-2-ium bromide 5, which after reflux in 1,2-dichloroethane eliminated hydrogen bromide and was transformed into the (E)-2-bromo-3-methylene-1,4-pentadienyl phenyl sulfoxide 6.

Full text of DOI:10.1080/10426500214293

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Phosphorus, Sulfur, and Silicon and the Related
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Alkatrienyl Sulfoxides and Sulfones. Part I. 3-
Methyl-1,2,4-pentatrienyl Phenyl Sulfoxide-Synthesis
and Electrophile-Induced Cyclization Reactions
Valerij Ch. Christov a & Ivaylo K. Ivanov a
a Department of Chemistry , University of Shoumen , Shoumen, Bulgaria
Published online: 27 Oct 2010.
To cite this article: Valerij Ch. Christov & Ivaylo K. Ivanov (2002) Alkatrienyl Sulfoxides and Sulfones. Part I. 3-Methyl-1,2,4-
pentatrienyl Phenyl Sulfoxide-Synthesis and Electrophile-Induced Cyclization Reactions, Phosphorus, Sulfur, and Silicon and
the Related Elements, 177:10, 2445-2454, DOI: 10.1080/10426500214293
To link to this article: http://dx.doi.org/10.1080/10426500214293
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Phosphorus, Sulfur and Silicon, 2002, Vol. 177:2445–2454
C
Copyright 2002 Taylor & Francis
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DOI: 10.1080/10426500290110667
ALKATRIENYL SULFOXIDES AND SULFONES.
PART I. 3-METHYL-1,2,4-PENTATRIENYL PHENYL
SULFOXIDE-SYNTHESIS AND
ELECTROPHILE-INDUCED CYCLIZATION
REACTIONS
Valerij Ch. Christov and Ivaylo K. Ivanov
Department of Chemistry, University of Shoumen,
Shoumen, Bulgaria
(Received February 12, 2002)
A method for the synthesis of the 3-methyl-1,2,4-pentatrienyl phenyl sul-
foxide 3 by [2,3]-sigmatropic rearrangement of the 3-methyl-1-penten-
4-yn-3-yl benzenesulfenate 2, formed in the reaction of the 3-methyl-
1-pentene-4-yn-2-ol 1 with phenylsulfenyl chloride has been created.
Possibilities and restrictions of the five-membered heterocyclization in
electrophile-induced reactions leading to the synthesis of the 5H-1,2-
oxathiol-2-ium salts 5, 7, and 8 have been explored. Chlorination of the
sulfoxide 2 proceeded with formation of the (E)-2-chloro-3-methylene-
1,4-pentadienyl phenyl sulfoxide 4, while the bromination afforded the
4-bromo-5H-1,2-oxathiol-2-ium bromide 5, which after reflux in 1,2-
dichloroethane eliminated hydrogen bromide and was transformed into
the (E)-2-bromo-3-methylene-1,4-pentadienyl phenyl sulfoxide 6.
Keywords: 2-Halogeno-3-methylene-1,4-pentadienyl phenyl sulfoxide;
3-methyl-1,2,4-pentatrienyl phenyl sulfoxide; 5H-1,2-oxathiol-2-ium
salts; electrophile-induced cyclic reactions; synthesis
INTRODUCTION
One of the characteristic reactions of the 1,2-alkadienes (allenes) are
the electrophilic addition reactions in which the addition products of the
reagent to one bond or to double bonds of the allenic system are usu-
ally obtained.1 5 Functionalized allenes are very interesting substrates
We are grateful for financial support of this work by a grant-in-aid for scientific re-
search (Project No. 11/08.05.2001) from the Research Fund of the University of Shoumen.
Special thanks to Mr. Plamen Petrov for the technical help in the synthesis of some
compounds.
Address correspondence to Valerij Ch. Christov, Department of Chemistry, University
of Shoumen, BG-9700 Shoumen, Bulgaria. E-mail: vchristo@shu-bg.net
2445

2446
V. Ch. Christov and I. K. Ivanov
as a material of choice to study the addition reactions on the carbon-
carbon double bonds.3,4 Unlike the allenic hydrocarbons, the presence of
a functional group linked to the allenic system considerably changes the
course of the reactions with electrophilic reagents. It has been shown3,4
that the reactions proceeded with cyclization of the allenic system bear-
ing a functional group to give heterocyclic compounds in most cases. It
makes the investigations on the functionalized allenes, more specifi-
cally in studying their reactions with electrophilic reagents, quite an
interesting and topical task.
Literature data on the electrophilic addition reactions to sulfur-
containing allenes (sulfoxides, sulfinates, and sulfones) shows that var-
16
ious five-membered heterocyclizations proceed in most cases.7,9,14
On the other hand, the reactions of the phosphorylated 1,2,4- and
1,3,4-alkatrienes with electrophiles lead to the synthesis of various
heterocyclic compounds depending on the kind of the electrophilic
reagent as well as on the position of the vinylic group. For exam-
ple, the halogenation reactions afford the 3- or 5-vinyl-substituted 2,5-
20
22
dihydro-1,2-oxaphospholes,17
while the reactions with sulfenyl20
and selenenyl19,20,23,24 chlorides give the thiophene- or selenophene-2-
or 3-phosphonates.
13
There are methods6
for the synthesis of sulfur-containing allenes
8
(sulfoxides,6 sulfinates,9 sulfinamides,10,11 and sulfones),12,13 includ-
ing reactions of -alkynols with sulfenyl or sulfinyl chlorides followed by
[2,3]-sigmatropic rearrangement. The synthetic utility of the remark-
able and efficient [2,3]-sigmatropic rearrangement of propargylic sulfe-
nates has been further demostrated, by W. H. Okamura and cowork-
ers, in a variety of preparations and interesting reactions of allenyl
28
30
sulfoxides,25
including the preparation of vinylallenes25
which
are useful intermediates in organic synthesis in general29 and natu-
ral polyenes, such as Vitamins A and D, in particular.30 Electrophilic
addition reactions to alkatrienyl sulfoxides and sulfones have not been
investigated to date.
As part of our general program on the synthesis and cyclization reac-
tions of highly unsaturated compounds, we decided to prepare a series
of alkatrienyl sulfoxides and sulfones so as to evaluate their chem-
ical reactivity with respect to make a study of the possibilities and
restrictions of the electrophile-induced cyclization reactions. The ar-
ticle documents the results on the synthesis and the reactions with
some electrophilic reagents (sulfuryl chloride, bromine, methyl- and
phenylsulfenyl chlorides and phenylselenenyl chloride) of 3-methyl-
1,2,4-pentatrienyl phenyl sulfoxide as an initial substrate for study of
the electrophile-induced heterocyclization reactions.

Alkatrienyl Sulfoxides and Sulfones
2447
RESULTS AND DISCUSSION
Since its discovery three decades ago,6 the reversible interconversion
of propargylic sulfenates to allenyl sulfoxides has become one of the
most studied and synthetically useful [2,3]-sigmatropic rearrangement
known. Numerous synthetic applications of the rearrangement have
been reported, including its use in the total synthesis of a variety of nat-
ural products such as steroids, prostaglandins, and leukotrienes.14 Our
strategy for the synthesis of 3-methyl-1,2,4-pentatrienyl phenyl sulfox-
ide 3 relies on the well-precedented [2,3]-sigmatropic shift of propar-
gylic sulfenates to -allenic sulfoxides. This compound was prepared
in 85% yield by reaction of freshly distilled phenylsulfenyl chloride
with 3-methyl-1-pentene-4-yn-3-ol 1 in the presence of triethylamine
and followed by [2,3]-sigmatropic rearrangement of the transient inter-
mediate 3-methyl-1-pentene-4-yn-3-yl benzenesulfenate 2 according to
Scheme 1.
SCHEME 1 Reagents and conditions: 1) PhSCl, Et3N dry ether, 40 C; 2)
dry ether, rt, 3 h.
After a conventional work-up, the resulting compound 3 was isolated
by column chromatography as a light yellow oil and identified by 1H and
13C NMR and IR spectra as well as elemental analysis.
The alkatrienyl sulfoxide 3 isolated in preparative amount allowed
us to study its chemical behavior in the reactions with electrophilic
reagents. From general considerations as well as from the litera-
ture data on the electrophilic addition reactions to sulfur-containing
16
24
allenes7,9,14
and to phosphorylated alkatrienes,17
the following
pathways of the reactions could be assumed: (1) attack of the reagent
on the C2 C3 double bond of the allenic system followed by neighboring
group participation of the internal nucleophile (sulfoxide group) and
ring closure to the five-membered cyclic compound; (2) attack of the
reagent on the C2 C3 double bond with formation of the 2,3-adduct;
(3) attack of the reagent on the C2 C3 double bond with formation
of the 1,3-alkadienic system and preparation of the 2,5-adduct; (4) at-
tack of the reagent on the C1 C2 double bond with formation of the
2,1-adduct; and (5) elimination reactions after realization of some of
above mentioned pathways (1–4).

2448
V. Ch. Christov and I. K. Ivanov
We established that reaction of the trienyl sulfoxides 3 with sulfuryl
chloride in dichloromethane proceeded with formation of 2-chloro-3-
methylene-1,4-pentadienyl phenyl sulfoxide 4 in 62% yield, according
to the following reaction sequence outlined in Scheme 2.
SCHEME 2 Reagents and conditions: 1) SO2Cl2, dry CH2Cl2, 10 C, rt, 3 h.
The resulting conjugated sulfoxide 4 was isolated by column chro-
1
matography as a yellow oil and identified by H and 13C NMR and IR
spectra as well as elemental analysis. A mechanistic rationale for the
formation of the sulfoxide 4 by an elimination reaction of hydrogen chlo-
ride would appear not to be straightforward. The result reported above
can be considered in terms of the following two assumptions (Scheme 3):
(1) intermediate formation of the stabilized carbenium ion A followed
by elimination of hydrogen chloride after an attach of the chloride anion
on the methyl group at C3-atom as has been shown by S. Braverman
and D. Reisman9 in the case of halogenation of allenyl sulfones; and (2)
deprotonation in the stage of the in situ generated cyclic sulfonium chlo-
ride B as shown by L. Horner and V. Binder7 in the reaction of allenyl
sulfoxides with electrophilic reagents and which was in corroboration of
our results on the reactions of the alkatrienyl sulfoxide 3 with bromine,
sulfenyl, and selenenyl chlorides.
SCHEME 3
In contrast to the chlorination, the bromination reaction of the
alkatrienyl sulfoxide 3 let to five-membered heterocyclization of the al-
lenic system of double bonds bearing a sulfoxide group (C C C S O)
to give the 4-bromo-5-methyl-2-phenyl-5-vinyl-5H-1,2-oxathiol-2-ium

Alkatrienyl Sulfoxides and Sulfones
2449
bromide 5 in 87% yield as shown in Scheme 4. Heating at reflux of
the cyclic sulfonium bromide 5 in 1,2-dichloroethane for 1.5 h pro-
voked elimination of hydrogen bromide and C5 O bond cleavage in
the ring with generation of the 2-bromo-3-methylene-1,4-pentadienyl
phenyl sulfoxide 6 in good yield (61%).
SCHEME 4 Reagents and conditions: 1) Br2, dry CH2Cl2, 10 C, rt, 3 h; 2)
dry ClCH2CH2Cl, reflux, 1.5 h.
The results reported in the Scheme 4 confirm our second assump-
tion in Scheme 3 that the reaction of alkatrienyl sulfoxide 3 with sul-
furyl chloride gives 2-chloro-3-methylene-1,4-pentadienyl phenyl sul-
foxide 4 probably proceeding through the 1,2-oxathiol-2-ium chloride
B. Another confirmation for that are the next results on the reactions
of the alkatrienyl sulfoxide 3 with sulfenyl and selenenyl chlorides.
Moreover, the configuration of the prepared 2-halogeno-3-methylene-
1,4-pentadienyl phenyl sulfoxides 4 and 6 is most likely (E). The (E)
stereochemistry could be based upon the chemical shift value of the
olefinic proton at the C1 atom. Although it was anticipated that the
1
olefinic proton of the (E)-isomers would be observed in the H NMR
spectrum upfield from the corresponding proton of the (Z)-isomers, with
the chemical shift value (s, 6.58 for 4 and s, 6.85 ppm for 6) alone we
cannot determine whether the 1,4-dienes 4 and 6 are (E) or (Z) iso-
mers. Nevertheless, the intermediate formation of the cyclic sulfonium
salts B and 5 predetermines the (E) configuration of the 1,4-alkadienyl
sulfoxides 4 and 6.
Reaction of 1,2,4-alkatrienyl sulfoxide 3 with methyl- and phenyl-
sulfenyl chlorides were also carried out with heterocyclization to give
the 5-methyl-2-phenyl-4-methyl(phenyl)thio-5-vinyl-5H-1,2-oxathiol-
2-ium chlorides 7 and 8 in 74 and 69% yields as shown in Scheme 5.
SCHEME 5 Reagents and conditions: 1) RSCl, dry CH2Cl2, 10 C, rt, 4 h.

2450
V. Ch. Christov and I. K. Ivanov
In a similar way, the 5-methyl-2-phenyl-4-phenylseleno-5-vinyl-5H-
1,2-oxathiol-2-ium chloride 9 was obtained with 62% yield in the in-
teraction of the alkatrienyl sulfoxide 3 with phenylselenenyl chloride
in dry dichloromethane at 10 C, according to the following reaction
sequence outlined in Scheme 6.
SCHEME 6 Reagents and conditions: 1) PhSeCl, dry CH2Cl2, 10 C, rt, 4 h.
The resulting cyclic sulfonium chlorides 7–9 were isolated by column
chromatography as yellow oils and identified by 1H and 13C NMR and
IR spectra as well as elemental analysis. The obtained compound 9
contains the isotope 77Se which is magnetically active and interacts
with other nuclei. This interaction becomes evident with the protons of
the neighboring groups which exhibit symmetric satelite signals of the
main signal in the 1H NMR spectra.
The attempts to eliminate hydrogen chloride of the cyclic sulfo-
nium chlorides 7–9 by heating at reflux in different solvents were not
successful—in all cases no traces of the expected 1,4-alkadienyl sul-
foxides were detected. Instead complex mixtures of polymerized and
decomposed products were obtained.
In conclusion, we note the following points from this investigation:
(1) the 3-methyl-1,2,4-pentatrienyl phenyl sulfoxide is readily available
by reaction of phenylsulfenyl chloride with 3-methyl-1-petene-4-yn-3-ol
followed by [2,3]-sigmatropic rearrangement; (2) electrophile-induced
cyclization reactions of the 3-methyl-1,2,4-pentatrienyl phenyl sulfox-
ide occur in all cases. The chlorination reaction leads directly to the
formation of (E)-2-chloro-3-methylene-1,4-pentadienyl sulfoxide while
interaction with bromine, sulfenyl, and selenenyl chlorides yields 5H-
1,2-oxathiol-2-ium salts. Reflux of the brominated cyclic sulfonium salt
eliminates hydrogen bromide and transforms it into the (E)-2-bromo-
3-methylene-1,4-pentadienyl sulfoxide; and (3) the 3-methyl-1,2,4-
pentatrienyl phenyl sulfoxide is a versatile synthone in organic syn-
thesis for interesting highly unsaturated and heterocyclic compounds.
The use the prepared 3-methylene-1,4-pentadienyl sulfoxides for
[4 + 2]-cycloadditions is the object of ongoing investigations. A contin-
uation of these studies toward the synthesis and electrophile-induced
cyclization reactions of other alkatrienyl sulfoxides and sulfones is cur-
rently in progress.

Alkatrienyl Sulfoxides and Sulfones
2451
EXPERIMENTAL
Method of Analysis
NMR spectra were obtained on a BRUKER DRX-250 spectrometer for
solutions in CDCl3. Chemical shifts are in parts per million downfield
from internal TMS (1H and 13C).
IR spectra were recorded with an IR-72 spectrophotometer (Carl
Zeiss, Jena). Elemental analyses were carried out by the University
of Shoumen Microanalytical Service Laboratory.
The melting points were measured in open capillary tubes and are
uncorrected. The solvents were purified by standard methods. All reac-
tions were carried out in oven-dried glassware under an argon atmo-
sphere and exclusion of moisture. All compounds were checked for their
purify on TLC plates.
Starting Materials
Methylsulfenyl chloride was freshly prepared from dimethyl disul-
fide and chlorine in dichloromethane and used without purification.
Phenylsulfenyl chloride was prepared from diphenyl disulfide and sul-
furyl chloride in dichloromethane and distilled in vacuo (b. p. 80–81/
20 mm Hg) before used. 3-Methyl-1-pentene-4-yn-3-ol and phenylsele-
nenyl chloride were commercially available and were purified by usual
methods.
Synthesis of 3-Methyl-1,2,4-pentatrienyl Phenyl
Sulfoxide (3)
To a solution of the mixture of the 3-methyl-1-pentene-4-yn-3-ol (1)
(30 mmol) and triethylamine (33 mmol) in dry diethyl ether (100 ml) at
40 C was added dropwise with stirring a solution of freshly distilled
phenylsulfenyl chloride (30 mmol) in the same solvent (20 ml). The
reaction mixture was stirred for 1 h at the same temperature and for
3 h at room temperature. Then the mixture was washed with water,
quenched with 2N HCl, extracted with ether, washed with saturated
NaCl, and dried over anhydrous sodium sulfate. After evaporation of
the solvent, the residue was chromatographed on a column (silica gel,
Kieselgel Merck 60 F254) with a mixture of ethyl acetate and hexane as
a eluent to give the pure product as a light yellow oil, which had the
following properties.
Yield 85%, yellow oil. Eluent for TLC: ethyl acetate: hexane 2:1,
Rf 0.53. Anal. Calcd. for C12H12OS (MW 204.282), %: S 16.02. Found, %:

2452
V. Ch. Christov and I. K. Ivanov
S 15.70. 1H NMR spectrum, : 1.98 (s, 3H, Me), 4.86–5.17 (m, 2H, CH2),
6.05 (s, 1H, C1H), 6.14–6.22 (m, 1H, C4H), 7.44–8.06 (m, 5H, Ph).
13C NMR spectrum, : 18.87, 89.79, 119.37, 113.33, 120.11, 124.72,
126.97, 130.54, 148.91, 196.52. IR spectrum (neat), cm 1: 1074 (S O),
1438, 1481 (Ph), 1614 (C C), 1948 (C C C).
Electrophile-Induced Cyclic Reactions of the
3-Methyl-1,2,4-pentatrienyl Phenyl Sulfoxide (3)
General Procedure
To a solution of the 3-methyl-1,2,4-pentatrienyl phenyl sulfoxide (3)
(10 mmol) in dry dichloromethane (20 ml) at 10 C was added dropwise
with stirring a solution of the electrophilic reagent (sulfuryl chloride,
bromine, methyl- or phenylsulfenyl chloride, phenylselenenyl chloride)
(10 mmol) in the same solvent (10 ml). The reaction mixture was stirred
for 1 h at the same temperature and for 3 or 4 h at room temperature.
In the case of bromination, dry ether was added to the reaction mix-
ture and the light brown crystals that precipitated were filtered and
washed with dry ether to give the pure product. In the other cases,
the solvent was removed using a rotatory evaporator and the residue
was chromatographed on a column (silica gel, Kieselgel Merck 60 F254
)
with a mixture of ethyl acetate and hexane as a eluent to give the pure
products, which had the following properties:
(E)-2-chloro-3-methylene-1,4-pentadienyl phenyl sulfoxide (4): Yield
62%, oil. Eluent for TLC: ethyl acetate:hexane1:25, Rf 0.47. Anal. Calcd.
for C12H11OSCl (MW 238.188), %: S 13.46, Cl 14.886. Found, %: S
1
13.36, Cl 14.98. H NMR spectrum, : 4.58–5.02 (m, 1H, C CHaHb),
5.01–5.09 (m, 1H, C CHaHb), 5.00–5.13 (m, 1H, CHa CHaHb), 5.18–
5.31 (m, 1H, CHa CHaHb), 6.35–6.43 (m, 1H, CHa CHaHb), 6.58 (s,
1H, CH), 7.35–8.04 (m, 5H, Ph). 13C NMR spectrum, : 119.45, 127.21,
128.33, 129.12, 131.53, 132.75, 136.87, 143.72, 145.46, 147.45. IR spec-
trum (neat), cm 1: 1071 (S O), 1442, 1484 (Ph), 1596, 1612, 1621, 1668
(C C).
4-Bromo-5-methyl-2-phenyl-5-vinyl-5H-1,2-oxathiol-2-ium bromide
(5): Yield 87%, m. p. 151–152 C. Eluent for TLC: ethyl acetate:hexane
2:1, Rf 0.72. Anal. Calcd. for C12H12OSBr2 (MW 364.09), %: S 8.81, Br
43.89. Found, %: S 9.03, Br 43.87. 1H NMR spectrum, : 2.87 (s, 3H, Me),
3
2
3
5.29 (dd, JHH 9.8 Hz, JHH 1.3 Hz, 1H, CHa CHaHb), 5.47 (dd, JHH
2
17.8 Hz, JHH 1.3 Hz, 1H, CHa CHaHb), 5.92–6.03 (m, CHa CHaHb),
7.21 (s, 1H, CH), 7.28–7.79 (m, 5H, Ph). 13C NMR spectrum, : 26.42,
85.93, 112.02, 118.47, 124.31, 126.55, 131.26, 135.44, 136.77, 142.87.
IR spectrum (nujol), cm 1: 1439, 1476 (Ph), 1574, 1617 (C C).

Alkatrienyl Sulfoxides and Sulfones
2453
A
solution of the 4-bromo-5-methyl-2-phenyl-5-vinyl-5H-1,2-
oxathiol-2-ium bromide (5) (5 mmol) in dry 1,2-dichloroethane (10 ml)
was heated at reflux for 1.5 h, after which the solvent was removed
under reduced pressure and the residue was purified by column
chromatography (silica gel, Kieselgel Merck 60 F254) with a mixture of
ethyl acetate and hexane as an eluent to give the pure product, which
had the following properties.
(E)-2-bromo-3-methylene-1,4-pentadienyl phenyl sulfoxide (6): Yield
61%, oil. Eluent for TLC: ethyl acetate:hexane1:10, Rf 0.54. Anal. Calcd.
for C12H11OSBr (MW 283.18), %: S 11.32, Br 28.22. Found, %: S 11.16,
Br 28.39. 1H NMR spectrum, : 4.65–5.05 (m, 1H, C CHaHb), 4.91–5.11
(m, 1H, C CHaHb), 5.06–5.19 (m, 1H, CHa CHaHb), 5.17–5.29 (m, 1H,
CHa CHaHb), 6.43–6.52 (m, 1H, CHa CHaHb), 6.85 (s, 1H, CH), 7.52–
8.28 (m, 5H, Ph). 13C NMR spectrum, : 118.14, 125.22, 126.03, 129.93,
130.22, 130.88, 145.34, 147.11, 148.52, 148.96. IR spectrum (neat),
cm 1: 1076 (S O), 1448, 1487 (Ph), 1601, 1611, 1624, 1655 (C C).
5-methyl-2-phenyl-4-methylthio-5-vinyl-5H-1,2-oxathiol-2-ium chlo-
ride (7): Yield 74%, yellow oil. Eluent for TLC: ethyl acetate:hexane
2:1, Rf 0.82. Anal. Calcd. for C12H12OS2Cl (MW 286.839), %: S 22.36,
Cl 12.36. Found, %: S 22.92, Cl 12.16. 1H NMR spectrum, : 2.69
(s, 3H, MeS), 2.87 (s, 3H, Me), 5.09 (dd, 3JHH 10.2 Hz, 2JHH 1.2 Hz, 1H,
CHa CHaHb), 5.43 (dd, 3JHH 18.1 Hz, 2JHH 1.2 Hz, 1H, CHa CHaHb),
6.14–6.28 (m, 1H, CHa CHaHb), 6.86 (s, 1H, CH), 6.73–8.11 (m, 5H,
Ph). 13C NMR spectrum, : 15.34, 25.32, 88.43, 95.78, 112.91, 128.55,
129.15, 130.76, 135.54, 144.03, 162.33. IR spectrum (neat), cm 1: 1440,
1484 (Ph), 1580, 1626 (C C).
5-methyl-2-phenyl-4-phenylthio-5-vinyl-5H-1,2-oxathiol-2-ium chlo-
ride (8): Yield 69%, yellow oil. Eluent for TLC: ethyl acetate:hexane
2:1, Rf 0.71. Anal. Calcd. for C18H17OS2Cl (MW 348.905), %: S 18.38,
Cl 10.16. Found, %: S 18.76, Cl 10.32. 1H NMR spectrum, : 2.77
3
2
(s, 3H, Me), 5.43 (dd, JHH 10.2 Hz, JHH 1.2 Hz, 1H, CHa CHaHb),
3
2
5.39 (dd, JHH 18.1 Hz, JHH 1.2 Hz, 1H, CHa CHaHb), 6.54–6.78 (m,
1H, CHa CHaHb), 6.90 (s, 1H, CH), 6.82–8.09 (m, 10H, 2Ph). 13C
NMR spectrum, : 29.34, 87.22, 112.32, 117.65, 123.95, 125.92, 126.65,
127.44, 127.86, 129.92, 135.04, 137.24, 147.66, 159.77. IR spectrum
(neat), cm 1: 1443, 1472 (Ph), 1577, 1620 (C C).
5-methyl-2-phenyl-4-phenylseleno-5-vinyl-5H-1,2-oxathiol-2-ium
chloride (9): Yield 62%, yellow oil. Eluent for TLC: ethyl acetate:hexane
3:1, Rf 0.53. Anal. Calcd. for C18H17OSClSe (MW 395.815), %: S 8.10,
Cl 8.956. Found, %: S 8.02, Cl 9.12. 1H NMR spectrum, : 2.84
3
2
(s, 3H, Me), 5.14 (dd, JHH 10.0 Hz, JHH 1.2 Hz, 1H, CHa CHaHb),
3
2
5.26 (dd, JHH 18.2 Hz, JHH 1.2 Hz, 1H, CHa CHaHb), 6.74–7.11

2454
V. Ch. Christov and I. K. Ivanov
(m, 1H, CHa CHaHb), 6.95 (s, 1H, CH), 7.51–8.22 (m, 10H, 2Ph). 13
C
NMR spectrum, : 23.7, 89.04, 108.45, 117.74, 124.29, 127.55, 129.03,
130.07, 131.14, 133.44, 134.87, 135.2, 144.82, 156.64. IR spectrum
(neat), cm 1: 1448, 1475 (Ph), 1583, 1622 (C C).
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