Reactions of selenium dihalides with vinylbenzenes

Article abstract of DOI:10.1134/S1070428017030022

Alkoxyselenation of vinylbenzenes with selenium dihalides was accomplished for the first time. The reaction with selenium dibromide was the most efficient. Selenium dibromide reacted with vinylbenzene and 1-chloro-4-(prop-1-en-2-yl)benzene in chloroform or methylene chloride in the presence of methanol or ethanol to give the corresponding Markovnikov adducts, bis(2-alkoxy-2-phenylethyl) selenides and bis[2-alkoxy-2-(4-chlorophenyl)propyl] selenides in 82–95% yield with high regioselectivity. Bis(2-halo-2-phenylethyl) selenides can be obtained at low temperature (–60°C).

Full text of DOI:10.1134/S1070428017030022

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2017, Vol. 53, No. 3, pp. 322–325. © Pleiades Publishing, Ltd., 2017.
Original Russian Text © V.A. Potapov, A.G. Khabibulina, M.V. Musalov, A.I. Albanov, S.V. Amosova, 2017, published in Zhurnal Organicheskoi Khimii,
2017, Vol. 53, No. 3, pp. 326–329.
Reactions of Selenium Dihalides with Vinylbenzenes
V. A. Potapov, A. G. Khabibulina, M. V. Musalov, A. I. Albanov, and S. V. Amosova*
Favorskii Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
*e-mail: amosova@irioch.irk.ru
Received October 26, 2016
Abstract—Alkoxyselenation of vinylbenzenes with selenium dihalides was accomplished for the first time.
The reaction with selenium dibromide was the most efficient. Selenium dibromide reacted with vinylbenzene
and 1-chloro-4-(prop-1-en-2-yl)benzene in chloroform or methylene chloride in the presence of methanol or
ethanol to give the corresponding Markovnikov adducts, bis(2-alkoxy-2-phenylethyl) selenides and bis[2-
alkoxy-2-(4-chlorophenyl)propyl] selenides in 82–95% yield with high regioselectivity. Bis(2-halo-2-phenyl-
ethyl) selenides can be obtained at low temperature (–60°C).
DOI: 10.1134/S1070428017030022
Functionalized organoselenium compounds exhibit
high biological activity [1, 2]. Development of effi-
cient methods for the preparation of practically impor-
tant organoselenium compounds is a topical problem.
temperature in chloroform, methylene chloride, or
carbon tetrachloride gave 1,2-dihaloethylbenzenes 1
and 2 and were accompanied by precipitation of ele-
mental selenium from the reaction mixture (Scheme 1).
In recent years, researchers in many countries have
been interested in selenium dihalides as new efficient
reagents for the synthesis of organoselenium com-
pounds [3–10]. Selenium dihalides are capable of
adding in regio- and stereoselective fashion to com-
pounds possessing double or triple bonds [3–10]. The
addition of selenium dihalides to C=C double bond
with an electron-donating substituent (alkyl or alkoxy
group) is regioselective, and the corresponding Mar-
kovnikov adducts are formed [6, 7]. Alkenes with elec-
tron-withdrawing substituents, such as methyl vinyl
ketone, acrylic acid and its esters, and acrylonitrile,
react with selenium dihalides to give mainly anti-
Markovnikov adducts [8, 9].
Scheme 1.
CH2Cl2 or CHCl3
20–25°C
X
SeX2
+
+ Se↓
Ph
X
H2C
Ph
1, 2
1, X = Cl; 2, X = Br.
In the reactions of selenium dichloride and di-
bromide with vinylbenzene at reduced temperature (at
–78°C in methylene chloride or at –60°C in chloro-
form) we succeeded in obtaining the addition products,
bis(2-halo-2-phenylethyl) selenides 3 and 4 together
with halogenation products 1 and 2 (Scheme 2). The
yield of selenide 3 was 40%, whereas selenide 4 was
the major product (75%). We failed to isolate pure
compounds 3 and 4 by column chromatography on
silica gel or aluminum oxide, since they slowly decom-
posed in solution at room temperature with formation
of a poorly soluble solid.
Addition of selenium dihalides to vinylbenzene has
not been reported previously. According to Migalina
et al. [11], reactions of selenium tetrahalides with
vinylbenzene lead to the formation of double bond
halogenation products, whereas no addition products
were detected. Reactions of selenium dihalides with
phenyl vinyl ether and vinyl benzene afforded mainly
double bond halogenation products [6].
Molecules 3 and 4 possess both electrophilic group
(CHCl or CHBr) and nucleophilic center (selenium
atom). It may be presumed that the halogen atom in 3
or 4 is highly reactive due to strong anchimeric effect
of the selenium atom [10] and activation by the phenyl
In this work we studied the addition of selenium
dihalides to vinylbenzenes. The reactions of selenium
dichloride and dibromide with vinylbenzene at room
322

REACTIONS OF SELENIUM DIHALIDES WITH VINYLBENZENES
323
Scheme 2.
CH2Cl2, –78°C or
CHCl3, –60°C
X
X
X
SeX2
+
2
+
Ph
Se
X
H2C
Ph
Ph
Ph
3, 4
1, 2
3, X = Cl; 4, X = Br.
the CH2 carbon atom was measured in the 13C NMR
spectra; the value 66–70 Hz corresponded to direct
coupling (1JSe–C). Thus, the selenium atom adds to the
terminal carbon atom of vinylbenzenes, i.e., Markov-
nikov adducts are formed in all cases.
group; therefore, compounds 3 and 4 are capable of
undergoing intermolecular nucleophilic substitution
where the selenium atom of another molecule acts as
nucleophile. As a result, the corresponding selenonium
salts are formed.
Each compound 3–8 was a mixture of two dia-
stereoisomers (dl and meso) at a ratio of 1:(1–1.2)
which were characterized by different signals in the
1H, 13C, and 77Se NMR spectra. The CH2Se and CHX
(X = OAlk, Cl) signals in the 13C NMR spectra of 3–8
were generally doublets, and each signal belonged to
a single diastereoisomer; however, in some cases,
signals of two diastereoisomers coincided and ap-
peared as one signal. One diastereoisomer of 5–7 pre-
dominated (ratio 1:1.2), and it was possible to reliably
assign signals to each diastereoisomer.
Unlike the addition reactions, alkoxyselenation of
vinylbenzene and 1-chloro-4-(prop-1-en-2-yl)benzene
with selenium dihalides in chloroform (or methylene
chloride) in the presence of methanol or ethanol was
selective (Scheme 3). Methoxyselenation was the most
efficient when selenium dibromide was used, the
chloroform–methanol ratio being 3:1. To achieve
a high yield and chemoselectivity, it is advisable to
carry out the reaction at reduced temperature (–20°C).
The yields of alkoxyselenation products 5 and 6 from
vinylbenzene were 82–83%; bis[2-alkoxy-2-(4-chloro-
phenyl)propyl] selenides 7 and 8 were formed from
1-chloro-4-(prop-1-en-2-yl)benzene in almost quan-
titative yield (93–95%).
In summary, products of addition of selenium
dihalides to vinylbenzene have been isolated. Alkoxy-
selenation of vinylbenzenes with selenium dihalides in
the presence of methanol and ethanol has been accom-
plished for the first time, and previously unknown
Markovnikov adducts have been synthesized. On the
basis of this reaction, an efficient procedure has been
developed for the regioselective synthesis of bis(2-al-
koxy-2-phenylethyl) selenides and bis[2-alkoxy-2-(4-
chlorophenyl)propyl] selenides as promising inter-
mediate products for organic synthesis and potential
biologically active compounds.
Scheme 3.
R
SeX2
+ 2
H2C
Ar
CHCl3 (CH2Cl2)–NaHCO3–AlkOH
–20 to 20–25°C
R
R
Se
Ar
AlkO
Ar
OAlk
5–8
5, R = H, Ar = Ph, Alk = Me; 6, R = H, Ar = Ph, Alk = Et;
7, R = Me, Ar = 4-ClC6H4, Alk = Me; 8, R = Me, Ar =
4-ClC6H4, Alk = Et; X = Cl, Br.
EXPERIMENTAL
The NMR spectra were recorded on a Bruker DPX-
400 spectrometer in CDCl3 at 400.13 (1H, HMDS),
100.61 (13C, HMDS), and 76.30 MHz (77Se, Me2Se).
The elemental analyses were obtained with a Thermo
Flash EA1112 analyzer. The solvents used were pre-
liminarily dried and distilled. Selenium dichloride and
dibromide were prepared by reactions of elemental
selenium with sulfuryl chloride and bromine, respec-
tively [4–10]. Dihaloethylbenzenes 1 and 2 were
described previously [11].
The alkoxyselenation with selenium dichloride was
less selective, and the yield of compounds 5–8 was
lower (53–72%) than in the reactions with selenium
dibromide. Unlike compounds 5–7, selenide 8 turned
out to be unstable, and it slowly decomposed on
storage at room temperature with formation of an in-
soluble solid.
The structure of compounds 3–8 was confirmed by
1H and 13C NMR spectra and elemental analyses (for
5–7). Compounds 4–6 were also characterized by 77Se
NMR spectra, and the 77Se–13C coupling constant with
Bis(2-chloro-2-phenylethyl) selenide (3). A solu-
tion of 0.52 g (5 mmol) of vinylbenzene in 30 mL of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 53 No. 3 2017

POTAPOV et al.
Major diastereoisomer. H NMR spectrum, δ, ppm:
324
1
methylene chloride was cooled to –78°C, and a solu-
tion of 2.5 mmol of SeCl2 in 20 mL of methylene
chloride, cooled to –78°C, was added dropwise. The
mixture was stirred for 30 min and allowed to warm up
to room temperature with stirring (2 h). The mixture
was filtered, washed with water, and dried over CaCl2,
the solvent was distilled off on a rotary evaporator, and
the residue was dried under reduced pressure. Yield of
mixture 1/3 0.592 g (48% of 1 and 40% of 3, accord-
2
3
2.74 d.d and 2.99 d.d (4H, CH2Se, J = 12.5, J = 7.8,
3
5.3 Hz), 3.26 s (6H, OCH3), 4.32 d.d (2H, CHO, J =
7.8, 5.3 Hz), 7.28–7.45 m (10H, Harom). 13C NMR
1
spectrum, δC, ppm: 31.67 (CH2Se, JC–Se = 67.5 Hz),
56.60 (CH3O), 84.26 (CHO), 126.50 (Carom), 127.71
(Carom), 128.22 (Carom), 141.05 (Carom). 77Se NMR spec-
trum: δSe 146.3 ppm.
1
Minor diastereoisomer. H NMR spectrum, δ, ppm:
1
ing to the H NMR data). We failed to isolate com-
pound 3 by silica gel chromatography using hexane–
carbon tetrachloride (1:6) as eluent. H NMR spec-
trum, δ, ppm: 2.74–2.79 m (4H, SeCH2), 4.49–4.55 m
(2H, CHCl), 7.09–7.21 m (10H, Ph). 13C NMR spec-
trum, δC, ppm: 33.10 and 33.44 (SeCH2), 61.97 and
62.26 (CHCl), 127.11 (Carom), 127.50 (Carom), 128.29
(Carom), 137.20 (Carom).
2
3
2.75 d.d and 2.97 d.d (4H, CH2Se, J = 12.5, J = 8.0,
3
5.3 Hz), 3.28 s (6H, OCH3), 4.36 d.d (2H, CHO, J =
1
8.0, 5.3 Hz), 7.28–7.45 m (10H, Ph). 13C NMR spec-
1
trum, δC, ppm: 31.84 (CH2Se, JC–Se = 66.7 Hz), 56.63
(CH3O), 84.25 (CHO), 126.44 (Carom), 127.71 (Carom),
128.23 (Carom), 141.07 (Carom). 77Se NMR spectrum:
δSe 146.9 ppm.
Bis(2-ethoxy-2-phenylethyl) selenide (6). Yield
82%, light yellow oily material. Found, %: C 63.37;
H 6.89; Se 20.67. C20H26O2Se. Calculated, %: C 63.65;
H 6.94; Se 20.92.
Bis(2-bromo-2-phenylethyl) selenide (4). A solu-
tion of 0.52 g (5 mmol) of vinylbenzene in 30 mL of
methylene chloride was cooled to –78°C, and a solu-
tion of 2.5 mmol of SeBr2 in 40 mL of methylene
chloride, cooled to –78°C, was added dropwise. The
mixture was stirred for 30 min and allowed to warm up
to room temperature with stirring (2 h). The mixture
was filtered, washed with water, and dried over CaCl2,
the solvent was distilled off on a rotary evaporator, and
the residue was dried under reduced pressure. Yield of
mixture 2/4 0.982 g (12% of 2 and 75% of 4, accord-
1
Major diastereoisomer. H NMR spectrum, δ, ppm:
3
1.14 t (6H, CH3, J = 7.0 Hz), 2.66 d.d and 2.92 d.d
2
3
(4H, CH2Se, J = 12.5, J = 8.1, 5.5 Hz), 3.34 q (4H,
3
OCH2), 4.35 d.d (2H, CHO, J = 8.1, 5.5 Hz), 7.21–
7.33 m (10H, Ph). 13C NMR spectrum, δC, ppm:
1
15.22 (CH3), 31.93 (CH2Se, JC–Se = 66.5 Hz), 64.36
(CH2O), 82.60 (CHO), 126.55 (Carom), 127.684 (Carom),
128.28 (Carom), 141.91 (Carom). 77Se NMR spectrum:
δSe 148.7 ppm.
1
ing to the H NMR data). We failed to isolate com-
pound 4 by silica gel chromatography using hexane–
1
1
carbon tetrachloride (1:6) as eluent. H NMR spec-
Minor diastereoisomer. H NMR spectrum, δ, ppm:
3
trum, δ, ppm: 3.44–3.54 m (4H, SeCH2), 4.59–4.63 m
(2H, CHBr), 6.78–6.87 m (10H, Ph). 13C NMR spec-
trum, δC, ppm: 34.89 (SeCH2, JC–Se = 70 Hz), 50.72
(CHBr), 126.05 (Carom), 127.47 (Carom), 128.51 (Carom),
138.26 (Carom).
1.16 t (6H, CH3, J = 6.9 Hz), 2.69 d.d and 2.92 d.d
2
3
(4H, CH2Se, J = 12.5, J = 8.1, 5.4 Hz), 3.34 q
3
(4H, OCH2), 4.39 d.d (2H, CHO, J = 8.1, 5.4 Hz),
7.21–7.33 m (10H, Ph). 13C NMR spectrum, δC, ppm:
1
15.24 (CH3), 32.06 (CH2Se, JC–Se = 66.5 Hz), 64.38
Bis(2-methoxy-2-phenylethyl) selenide (5). A so-
lution of 0.52 g (5 mmol) of vinylbenzene in a mixture
of 7 mL of methanol and 8 mL of chloroform was
cooled to –20°C, 0.42 g (5 mmol) of sodium hydrogen
carbonate was added, and a solution of 2.5 mmol of
selenium dibromide in 15 mL of chloroform, cooled to
–20°C, was added dropwise over a period of 5 min.
The mixture was stirred for 2 h at –20°C and for 1 h at
room temperature and filtered, the solvent was distilled
off on a rotary evaporator, and the residue was dried
under reduced pressure. Yield 0.72 g (83%), light
yellow oily material. Found, %: C 61.75; H 6.17;
Se 22.35. C18H22O2Se. Calculated, %: C 61.89;
H 6.35; Se 22.60.
(CH2O), 82.52 (CHO), 126.49 (Carom), 127.67 (Carom),
128.30 (Carom), 141.92 (Carom). 77Se NMR spectrum:
δSe 148.1 ppm.
Bis[2-(4-chlorophenyl)-2-methoxypropyl]
selenide (7). Yield 95%, light yellow oily material.
Found, %: C 53.79; H 5.40; Cl 16.86; Se 17.67.
C20H24Cl2O2Se. Calculated, %: C 53.83; H 5.42;
Cl 15.89; Se 17.69.
1
Major diastereoisomer. H NMR spectrum, δ, ppm:
2
1.57 s (6H, CH3), 2.60, 2.76 d (4H, CH2Se, J =
12.2 Hz), 3.04 s (6H, OCH3), 7.24 m and 7.29 m (8H,
Harom). 13C NMR spectrum, δC, ppm: 22.52 (CH3),
39.08 (CH2Se), 50.80 (CH3O), 78.95 (CO), 127.81
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 53 No. 3 2017

REACTIONS OF SELENIUM DIHALIDES WITH VINYLBENZENES
325
(Carom), 128.25 (Carom), 133.07 (Carom), 142.36 (Carom).
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Minor diastereoisomer. H NMR spectrum, δ, ppm:
2
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18.73 (CH3), 23.49 (CH3), 39.61 (CH2Se), 58.31
(CH2O), 78.48 (CO), 127.43 (Carom), 128.14 (Carom),
133.26 (Carom), 142.15 (Carom).
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