Reactions of selenium dichloride and dibromide with unsaturated ethers. Annulation of 2,3-dihydro-1,4-oxaselenine to the benzene ring

Article abstract of DOI:10.1016/j.tetlet.2011.06.071

Highly chemo-, regio-, and stereoselective syntheses of novel organoselenium compounds from selenium dichloride or dibromide and unsaturated ethers are described. The reactions of selenium dichloride with allyl and propargyl phenyl ethers afford either annulated products or bis-adducts depending on the conditions. The first examples of annulation of 3-chloromethyl- and 3-chloromethylene-2,3-dihydro-1,4-oxaselenine to the benzene ring are reported.

Full text of DOI:10.1016/j.tetlet.2011.06.071

Tetrahedron Letters 52 (2011) 4606–4610
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Reactions of selenium dichloride and dibromide with unsaturated ethers.
Annulation of 2,3-dihydro-1,4-oxaselenine to the benzene ring
⇑
⇑
Vladimir A. Potapov , Maxim V. Musalov, Svetlana V. Amosova
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Division of The Russian Academy of Sciences, 1 Favorsky Str., Irkutsk 664033, Russian Federation
a r t i c l e i n f o
a b s t r a c t
Article history:
Highly chemo-, regio-, and stereoselective syntheses of novel organoselenium compounds from selenium
dichloride or dibromide and unsaturated ethers are described. The reactions of selenium dichloride with
allyl and propargyl phenyl ethers afford either annulated products or bis-adducts depending on the con-
ditions. The first examples of annulation of 3-chloromethyl- and 3-chloromethylene-2,3-dihydro-1,4-
oxaselenine to the benzene ring are reported.
Received 29 April 2011
Revised 2 June 2011
Accepted 17 June 2011
Available online 25 June 2011
Ó 2011 Elsevier Ltd. All rights reserved.
Keywords:
Allyl phenyl ether
Propargyl phenyl ether
Selenium dichloride
Selenium dibromide
Unsaturated ethers
2,3-Dihydro-1,4-oxaselenine
Vinylic selenides
Selenium was considered a poison for many years, until Sch-
warz and Foltz identified it as a micronutrient for mammals and
bacteria.1 Since then, there has been growing interest in the syn-
thesis of organoselenium compounds2,3 due to their use in bioor-
ganic chemistry, enzymology, and medicine. These compounds
exhibit various types of biological activities3 including antitumor,
anti-inflammatory, antibacterial, and antifungal. Antioxidative
and glutathione peroxidase-like3 actions are among the most
important. Many selenium-containing compounds, which possess
biological activity, are heterocycles.3 The selenium-containing het-
erocyclic compound, abselen has demonstrated high glutathione
peroxidase-like activity.3 The synthesis of novel selenium-contain-
ing compounds and especially heterocycles, possessing promising
biologically active properties, represents an important challenge
for organoselenium chemists.
Electrophilic selenium reagents play an important role in mod-
ern organic synthesis.4 Recently, we studied reactions of the novel
electrophilic reagents,5–10 selenium dichloride and dibromide,
with compounds bearing double5–7 or triple bonds.8,9 Although
the presence of selenium dichloride and dibromide in the gas
phase and in solutions was demonstrated in the literature, none
of the selenium dihalides has been isolated as a pure compound.
It was shown that in solution, selenium dichloride underwent dis-
proportionation to Se2Cl2 and SeCl4, whereas selenium dibromide
was converted into Se2Br2 and bromine.11 Nevertheless, we found
that freshly prepared selenium dichloride and dibromide could be
used in situ for selective synthesis of organoselenium com-
pounds5–10 including heterocycles.5–8 The reactions of selenium
dichloride and dibromide with dimethyl diethynyl silane leading
to 3,6-dihalo-4,4-dimethyl-1,4-selenasilafulvenes represented the
first syntheses of organoselenium compounds using selenium
dihalides.8 Efficient syntheses of novel 4-, 5-, and 6-membered
selenium heterocycles via the addition of selenium dichloride
and dibromide to divinyl sulfide,5 divinyl selenide,6 and divinyl
sulfone7 were elaborated.
The reaction of selenium dichloride with methoxybenzene
afforded bis(4-methoxyphenyl)selenide.10a This reaction was the
first example of aromatic electrophilic substitution with selenium
dihalides. Although the methoxy group activated the benzene ring
with respect to electrophilic substitution, heating the reaction mix-
ture (reflux of a chloroform solution) was necessary to obtain a
high yield (91%) of bis(4-methoxyphenyl)selenide.
Since selenium dichloride is able to participate in both electro-
philic substitution and addition, this opens the possibility to com-
bine two types of reactions in one molecule. In this work, we report
our studies on the reactions of selenium dichloride and dibromide
with propargyl phenyl, allyl phenyl, and vinyl organyl ethers. A no-
vel approach to annulation of selenium heterocycles, which is
based on the combination of addition and electrophilic substitu-
tion with selenium dichloride, is proposed. Selenium dichloride
was prepared from selenium and sulfuryl chloride in carbon
⇑
Corresponding authors. Tel.: +7 3952 424954; fax: +7 3952 419346 (V.A.P.); tel.:
+7 3952 425885; fax: +7 3952 419346 (S.V.A.).
E-mail addresses: v.a.potapov@mail.ru (V.A. Potapov), amosova@irioch.irk.ru
(S.V. Amosova).
0040-4039/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2011.06.071

V. A. Potapov et al. / Tetrahedron Letters 52 (2011) 4606–4610
4607
O
O
O
O
O
O
reflux
-[HCl]
reflux
-[HCl]
CHCl3
CHCl3
SeCl2
Cl
SeCl2
Cl
+
+
Cl
Cl
-60 o C
to rt
-60 o C
to rt
+
Se
+
Se
Se
Se
Cl
Cl
1
4
A
Scheme 3.
Scheme 1.
proceeds in a regio- and stereoselective manner, represents an-
other general synthetic approach to vinylic selenides.18
tetrachloride or chloroform, and selenium dibromide was obtained
from selenium and bromine in the same solvents. The selenium
dihalides were used in reactions immediately after their
preparation.
The reaction of selenium dichloride with propargyl phenyl ether
proceeded in a chemo-, regio-, and stereoselective manner to af-
ford the novel heterocycle, E-3-chloromethylene-2,3-dihydro-1,4-
benzoxaselenine (1),12,13 in 82% yield (Scheme 1). The regio- and
stereoselectivities of the reaction can be rationalized by a probable
formation of intermediate selenirenium cation A followed by elec-
trophilic aromatic substitution.
The chemo- and regioselective synthesis of the novel annulated
heterocycle,
3-chloromethyl-2,3-dihydro-1,4-benzoxaselenine
(4),12,19 in 90% yield was elaborated based on the reaction of sele-
nium dichloride with allyl phenyl ether (Scheme 3).
A solution of selenium dichloride and a solution of an equimolar
amount of allyl phenyl ether in chloroform were added separately
and simultaneously to a flask at low temperature (À60 °C) fol-
lowed by stirring at room temperature and heating the reaction
mixture to reflux to carry out the electrophilic aromatic substitu-
tion reaction.
The reaction was carried out in chloroform using equimolar
amounts of the reagents. The best yield (82%) was achieved when
selenium dichloride and a solution of the ether were added sepa-
rately and simultaneously to a flask with chloroform cooled to
À60 °C followed by stirring at room temperature and heating the
reaction mixture to reflux. Since the addition of selenium dichlo-
ride to the triple bond proceeds more easily compared with the
electrophilic substitution, we suppose that the addition occurred
at the temperature from À60 to 20 °C, whereas the electrophilic
aromatic substitution required heating. It is noteworthy that reflux
was necessary to perform the electrophilic aromatic substitution of
methoxybenzene with selenium dichloride in high yield.10a
When we used excess propargyl phenyl ether, the reaction of
selenium dichloride afforded the anti-Markovnikov product, E,E-
bis(3-phenoxy-1-chloro-1-propen-2-yl) selenide (2),14,15 in 94%
yield. Selenium dichloride was added to a solution of propargyl
phenyl ether (twofold molar excess) in CCl4 at À20 °C followed
by stirring at room temperature (Scheme 2). Thus, the reaction of
selenium dichloride with propargyl phenyl ether was directed
selectively either to annulated product 1 or to bis-adduct 2
depending on the conditions.
Under the conditions for the formation of heterocycle 1, sele-
nium dibromide did not give an annulated product. We assume
that selenium dibromide possesses lower reactivity with respect
to electrophilic aromatic substitution than selenium dichloride. In-
deed, we failed to obtain bis(4-methoxyphenyl)selenide from sele-
nium dibromide and methoxybenzene under the conditions for the
preparation of this compound from selenium dichloride.10a How-
ever, when we used excess propargyl phenyl ether, the reaction
with selenium dibromide led to the anti-Markovnikov product,
E,E-bis(3-phenoxy-1-bromo-1-propen-2-yl) selenide (3)14,16 in
96% yield (Scheme 2).
Unlike the reaction of selenium dichloride with excess propar-
gyl phenyl ether leading to anti-Markovnikov product 2, selenium
dichloride reacted with excess allyl phenyl ether to afford the
Markovnikov product, bis(3-phenoxy-2-chloropropyl) selenide
(5)14,20 in 98% yield (Scheme 4).
The question arose as to why the addition of selenium dichlo-
ride to excess allyl phenyl ether occurred at the terminal carbon
atom of the allyl group to give Markovnikov product 5, whereas
formation of the annulated product 4 was accompanied by the
addition of selenium dichloride to the central carbon atom of the
allyl group? Assuming the formation of the final products is deter-
mined by two main factors: (a) the thermodynamic stability of the
product and (b) the reversibility of the addition reaction, the addi-
tion of selenium dichloride to the double bond is reversible and
this makes possible the interconversion of Markovnikov and anti-
Markovnikov products. The addition of selenium dichloride to ex-
cess allyl phenyl ether gives the Markovnikov product since it is
thermodynamically more stable. However, in the case of the annu-
lation reaction, the addition occurs to the central carbon atom of
the allyl group since six-membered oxaselenine 4 is thermody-
namically preferred over the hypothetical seven-membered het-
erocycle, which could be formed if the addition takes place to the
terminal carbon atom of the allyl group.
Similar to the reaction of selenium dibromide with propargyl
phenyl ether, selenium dibromide reacted with allyl phenyl ether
to give bis-adducts rather than an annulated product. However,
the formation of both Markovnikov and anti-Markovnikov prod-
ucts 6 and 7 in a 1:2 ratio (92% total yield) was observed in the
reaction of selenium dibromide with excess allyl phenyl ether
(Scheme 5).14,21
The bromine atom is larger than a chlorine atom and, therefore,
steric hindrance is a more important factor for the addition of the
bromide anion to the intermediate seleniranium cation. Attack by
the bromine anion at the terminal unhindered carbon atom of
the intermediate seleniranium cation leads to anti-Markovnikov
product 7, the alternative pathway leading to Markovnikov prod-
uct 6 is less probable (Scheme 5). From this viewpoint, the proba-
bility of anti-Markovnikov products is higher for selenium
It should be emphasized that the reactions of selenium diha-
lides with propargyl phenyl ether are highly chemo-, regio-, and
stereoselective and give the products 1–3 bearing a vinylseleno
group in high yields. Vinylic selenides are powerful tools for organ-
ic synthesis serving as versatile precursors and synthons.2,17 Be-
sides the reactions of selenium electrophiles with alkynes, the
addition of selenium nucleophiles to the triple bond, which often
X
X
CCl4
O
Ph
SeX2
+
-20 o C to rt
Cl
Cl
OPh
PhO
O
CCl4
Se
Ph
PhO
Se
OPh
SeCl2
+
-20 oC to rt
2,3
X = Cl (2), Br (3)
5
Scheme 2.
Scheme 4.

4608
V. A. Potapov et al. / Tetrahedron Letters 52 (2011) 4606–4610
Br
Br
mation of some by-products was observed in the reaction with
selenium dichloride. These reactions represent the first examples
of selenation of vinylic ethers with selenium halides.
OPh
Br
OPh
PhO
CCl4
SeBr2
PhO
+
+
-20 oC
Se
Se
Why halogenation of the double bond predominates over the
selenation for phenyl vinyl and divinyl ethers, whereas alkyl vinyl
ethers give bis-adducts 12–15, is not clear. The second substituent
(phenyl, vinyl, or alkyl groups) imparts a considerable influence on
the reactivity of vinyl organyl ethers in reactions with selenium
dihalides. An unshared electron pair on the oxygen atom is able
to stabilize the adjacent positive charge in the intermediate cation,
which is formed by addition of selenium dihalides to the vinyloxy
group. However, the vinyl group or the phenyl moiety is capable of
conjugation with the unshared electron pair of the oxygen and
thus decrease the ability of the oxygen atom to stabilize the adja-
cent positive charge. On the contrary, electron-donating alkyl
groups increase the stabilization of the adjacent cation center.
We suppose that the selenation proceeds as an electrophilic pro-
cess via seleniranium intermediates, whereas concurrent haloge-
Br
OPh
OPh
6
7
Br
Br
OPh
OPh
OPh
+
Se
Br
Se
Se +
Br
Br
OPh
Br
OPh
Scheme 5.
X
RO
RO
X
X
RO
Se
SeX2
+
+ Se
X
nation by selenium dihalides is
a molecular reaction (e.g.,
8-11
cycloaddition). Phenyl vinyl and divinyl ethers, which possess a
conjugated electron system, react with selenium dihalides to form
halogenated products and elemental selenium via probable [3+2]
cycloaddition (Scheme 6). Examples of increasing the rate of cyclo-
addition reactions with an increase of conjugation are well known
for the Diels–Alder reaction.26 It is noteworthy that the reactivity
of vinyl phenyl ether in the Diels–Alder reaction is considerably
higher than alkyl vinyl ethers.26b It is relevant to mention that sty-
rene, which possesses a double bond in conjugation with a phenyl
ring, also reacted with selenium dihalides to form halogenation
products.27
X = Cl (8,10), Br (9,11); R = Ph (8,9), CH=CH2 (10,11)
Scheme 6.
dibromide compared with selenium dichloride. We found that
heating the mixture of products 6 and 7 led to conversion of
anti-Markovnikov product 7 into Markovnikov product 6. Reflux-
ing a CCl4 solution for 5 h led to a change in the ratio of products
6 and 7 from 1:2 to 5:1 (Scheme 5).
These data can be explained by the possible reversibility of the
addition of selenium dibromide to allyl phenyl ether (Scheme 5).
Anti-Markovnikov selenide 7 is a kinetic product, which is con-
verted into the more stable thermodynamic Markovnikov product
6 upon heating.
The structural assignments of novel compounds 1–7 and 12–15
were made using 1H, 13C, and 77Se NMR spectroscopy including
NOESY. The regiochemistry of the addition was defined by estima-
tion of the values of the spin-spin coupling constants 1JC–Se. Values
within 50–150 Hz28 correspond to direct coupling constants 1JC–Se
,
Apart from allyl and propargyl phenyl ethers, we regarded vinyl
phenyl ether as a probable candidate for the annulation reaction
with selenium dichloride. This compound contains a highly reac-
tive double bond along with the benzene ring activated with re-
spect to electrophilic aromatic substitution. In spite of the fact
that vinyl ethers are among the most reactive compounds in elec-
trophilic addition, there are no data in the literature on reactions of
selenium halides with vinyl ethers. We attempted the annulation
of vinyl phenyl ether with selenium dichloride under the condi-
tions for the synthesis of heterocycles 1 and 4. However, the reac-
tion gave predominantly products of halogenation of the vinyloxy
group, 1,2-dihaloethyloxybenzenes 8 and 9, rather than selenation
products (Scheme 6).
A similar reaction took place in the case of divinyl ether: sele-
nium dihalides acted as halogenation reagents to form products
10 and 11. Surprisingly, in contrast to divinyl and vinyl phenyl
ethers, alkyl vinyl ethers reacted with selenium dichloride and
dibromide to produce selenation products. The addition of sele-
nium dihalides to alkyl vinyl ether afforded bis(2-alkoxy-2-halo-
ethyl) selenides 12–1522–25 in 80–98% yields (Scheme 7). The
reaction of selenium dibromide proceeded with high selectivity
to give selenides 13 and 15 in 98% and 93% yields, whereas the for-
and, therefore, this carbon atom is regarded as bonding with the
selenium atom. For example, the carbon atom of the CH-group as
well as the aromatic carbon atom not bearing protons revealed di-
rect coupling constants 1JC–Se (68 and 104 Hz) in the 13C NMR spec-
tra of heterocycle 4.19 Therefore, the selenium atom is bonded with
the central carbon atom of the allyl group and with the carbon
atom of the benzene ring in heterocycle 4. The 13C NMR spectrum
1
of compound 5 showed a direct coupling constant JC–Se (65 Hz)
with the carbon atom of the CH2-group.20 This means that the
addition takes place at the terminal carbon atom of the allyl group
to afford the Markovnikov product. In the case of compounds 2,15
and 3,16 direct coupling constants 1JC–Se (115 and 117 Hz) with car-
bon atoms not bearing protons were observed. Thus, the addition
takes place at the central carbon atom of the propargyl group to af-
ford anti-Markovnikov products. The stereochemistry of com-
pounds 1–3 was assigned based on the NOESY spectra. The
selenides 5–7 and 12–15, as compounds with two chiral carbon
atoms, consist of two diastereomers (d,l and meso-forms) in a 1:1
ratio. The fragments SeCH2CHX of selenides 5–7 and 12–15 re-
vealed different signals for each of the two diastereomers in the
NMR spectra.
In conclusion, efficient syntheses of novel compounds 1–7 and
12–15, which are potential candidates with respect to biological
activity and as intermediates for preparation of functionalized
organoselenium compounds, have been elaborated. A convenient
approach to annulation of 2,3-dihydro-1,4-oxaselenine to the ben-
zene ring by the reactions of selenium dichloride with allyl and
propargyl phenyl ethers is proposed. Depending on the conditions,
the reactions can be directed selectively either to annulation or to
the formation of bis-adducts. The first examples of selenation of
vinylic ethers with selenium halides are also described.
X
X
CCl4
RO
Se
SeX2
+
RO
OR
-20 o C to rt
12-15
X = Cl (12, 14), Br (13, 15); R = Bu (12, 13), i-Bu (14, 15)
Scheme 7.

V. A. Potapov et al. / Tetrahedron Letters 52 (2011) 4606–4610
4609
14. Typical procedure for the preparation of selenides 2,3 and 5–7. A solution of SeBr2
was prepared from Se (0.395 g, 5 mmol) and Br2 (0.8 g, 5 mmol) in CCl4 (20 ml).
The solution of SeBr2 thus prepared was added dropwise over 1 h to a solution
of propargyl phenyl ether (1.32 g, 10 mmol) in CCl4 (50 ml) cooled to À20 °C.
After stirring for 2 h at À20 °C, the cooling bath was removed and the mixture
was allowed to warm and stirred at room temperature for 1 h. The solvent was
evaporated and the crude product was purified by chromatography on a short
column of silica gel (eluent:hexane) to give selenide 3 (2.43 g, 96% yield) as a
yellow oil.
Acknowledgments
Financial support from the Russian Academy of Sciences
(Programs 7.19 and 5.1.8) and the Russian Foundation for Basic
Research (Grant Nos. 10-03-00543 and 10-03-92666) is gratefully
acknowledged.
15. E,E-bis(3-phenoxy-1-chloro-1-propen-2-yl) selenide (2), yellow oil. 1H NMR
(400 MHz, CDCl3): d 4.71 (s, 4H, OCH2), 6.43 (s, 2H, =CHCl), 6.78 (m, 4H, C6H5),
6.85 (m, 2H, C6H5), 7.13 (m, 4H, C6H5). 13C NMR (100.6 MHz, CDCl3): d 66.25
(OCH2), 114.88 (C6H5, ortho), 121.49 (C6H5, para), 123.55 (=CHCl), 128.95 (SeC,
1JSeC = 115 Hz), 129.54 (C6H5, meta), 157.95 (C6H5, ipso). 77Se NMR (76.3 MHz,
CDCl3): d 416. Anal. Calcd for C18H16O2Cl2Se: C, 52.20; H, 3.89; Cl, 17.12; Se
19.06. Found: C, 51.96; H, 3.94; Cl, 16.93; Se, 19.35.
References and notes
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6.84 (m, 2H, C6H5), 7.13 (m, 4H, C6H5). 13C NMR (100.6 MHz, CDCl3): d 68.54
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1
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Polyhedron 1985, 4, 65; (c) Lamoureux, M.; Milne, J. Polyhedron 1990, 9, 589; (d)
Steudel, R.; Jensen, D.; Baumgart, F. Polyhedron 1990, 9, 1199.
17. (a) Perin, G.; Lenardão, E. J.; Jacob, R. G.; Panatieri, R. B. Chem. Rev. 2009, 109,
1277; (b) Comasseto, J. V.; Ling, L. W.; Petragnani, N.; Stefani, H. A. Synthesis
1997, 373; (c) Potapov, V. A.; Amosova, S. V. Russ. J. Org. Chem. 1996, 32, 1142;
(d) Martynov, A. V.; Potapov, V. A.; Amosova, S. V.; Makhaeva, N. A.; Beletskaya,
I. P.; Hevesi, L. J. Organomet. Chem. 2003, 674, 101; (e) Potapov, V. A.; Amosova,
S. V.; Dudareva, G. N.; Shestakova, V. Yu.; Zhnikin, A. R.; Petrov, B. V.;
Aksamentova, T. N. Rec. Trav. Chim. 1996, 115, 443; (f) Potapov, V. A.; Amosova,
S. V.; Petrov, B. V. Phosphorus, Sulfur Silicon Relat. Elem. 1998, 136–138, 587; (g)
Martynov, A. V.; Potapov, V. A.; Amosova, S. V.; Albanov, A. I. Russ. J. Gen. Chem.
2003, 73, 1398.
18. (a) Comasseto, J. V. J. Organomet. Chem. 1983, 253, 131; (b) Potapov, V. A.;
Amosova, S. V. Phosphorus, Sulfur Silicon Relat. Elem. 1993, 79, 277; (c) Potapov, V.
A.; Amosova, S. V.; Shestakova, V. Yu. Phosphorus, Sulfur Silicon Relat. Elem. 1998,
136–138, 205; (d) Amosova, S. V.; Elokhina, V. N.; Nakhmanovich, A. S.; Larina, L.
I.; Martynov, A. V.; Steele, B. R.; Potapov, V. A. Tetrahedron Lett. 2008, 49, 974; (e)
Potapov, V. A.; Elokhina, V. N.; Larina, L. I.; Yaroshenko, T. I.; Tatarinova, A. A.;
Amosova, S. V. J. Organomet. Chem. 2009, 694, 3679; (f) Comasseto, J. V.; Ferreira,
J. T. B.; Petragnani, N. J. Organomet. Chem. 1981, 216, 287.
19. 3-Chloromethyl-2,3-dihydro-1,4-benzoxaselenine (4), yellow oil. 1H NMR
(400 MHz, CDCl3):
d
3.50 (m, 1H, CHSe), 3.75 (dd, 1H, CH2Cl, 2J = 10.9,
3J = 4.6 Hz), 3.92 (dd, 1H, CH2Cl, 2J = 10.9, 3J = 11.2 Hz), 4.10 (dd, 1H, CH2O,
2J = 12.1, 3J = 1.0 Hz), 4.65 (dd, 1H, CH2O, 2J = 12.1, 3J = 3.1 Hz), 6.85 (m, 2H,
C6H4) 6.95 (m, 1H, C6H4), 7.07 (m, 1H, C6H4). 13C NMR (100.6 MHz, CDCl3): d
35.54 (CHSe, 1JC–Se 68 Hz), 44.61 (CH2Cl), 65.85 (CH2O), 114.81 (C6H4, CSe, 1JC–Se
104 Hz), 119.48 (C6H4), 122.98 (C6H4), 126.56 (C6H4), 129.37 (C6H4), 154.07
(C6H4, CO.). 77Se NMR (76.3 MHz, CDCl3): d 279. GC–MS: m/z (rel intensity) 248
(86) [M]+Å, 199 (22) [M-CH2Cl]+, 172 (38) [C6H7OSe]+Å, 144 (90) [C2H5ClSe]+Å, 63
(60) [COCl]+, 39 (100) [C3H3]+Å. Anal. Calcd for C9H9OClSe: C, 43.66; H, 3.66; Cl,
14.32; Se 31.89. Found: C, 43.34; H, 3.85; Cl, 13.98; Se, 32.24.
20. Bis(3-phenyloxy-2-chloropropyl) selenide (5), yellow oil (dr = 1:1). 1H NMR
(400 MHz, CDCl3): d 3.16 (m, 2H, CH2Se), 3.27 (m, 2H, CH2Se), 4.21–4.40 (m,
6H, CH2O, CHCl), 6.84 (m, 4H, C6H5), 6.91 (m, 2H, C6H5), 7.21 (m, 4H, C6H5). 13
C
1
NMR (100.6 MHz, CDCl3): d 29.71, 29.75 (CH2Se, JC–Se 65 Hz), 58.13, 58.20
(CHCl), 69.96, 70.02 (CH2O), 114.79 (C6H5, ortho), 121.59 (C6H5, para), 129.55
(C6H5, meta), 158.02 (C6H5, ipso). Anal. Calcd for C18H20O2Cl2Se: C, 51.69; H,
4.82; Cl, 16.95; Se 18.88. Found: C, 51.46; H, 4.97; Cl, 17.14; Se, 19.07.
21. Bis(3-phenyloxy-2-bromopropyl) selenide (6) (dr = 1:1). 1H NMR (400 MHz,
CDCl3): d 3.21 (m, 2H, CH2Se), 3.31 (m, 2H, CH2Se), 3.82 (m, 2H, CHBr), 4.20 (m,
2H, CH2O), 4.36 (m, 2H, CH2O), 6.85 (m, 4H, C6H5), 6.91 (m, 2H, C6H5), 7.22 (m,
1
4H, C6H5). 13C NMR (100.6 MHz, CDCl3): d 29.08, 29.14 (CH2Se, JC–Se 66 Hz),
48.78, 48.82 (CHBr), 69.09, 69.17 (CH2O), 113.92 (C6H5, ortho), 120.66 (C6H5,
para), 128.67 (C6H5, meta), 156.93 (C6H5, ipso). Bis(3-phenyloxy-1-
bromopropyl-2) selenide (7) (dr = 1:1). 1H NMR (400 MHz, CDCl3): d 3.50 (m,
2H, CHSe), 3.91 (m, 4H, CH2Br), 4.30 (m, 2H, CH2O), 4.45 (m, 2H, CH2O), 6.86
(m, 4H, C6H5), 6.92 (m, 2H, C6H5), 7.23 (m, 4H, C6H5). 13C NMR (100.6 MHz,
CDCl3): d 33.08, 33.15 (CH2Br), 40.48, 40.71 (CHSe), 69.75, 69.81 (CH2O),
113.85 (C6H5, ortho), 120.53 (C6H5, para), 128.67 (C6H5, meta), 157.16 (C6H5,
ipso). Anal. Calcd for C18H20O2Br2Se: C, 42.63; H, 3.98; Br, 31.51; Se 15.57.
Found: C, 42.44; H, 4.11; Br, 31.71; Se, 15.34. Attempted isolation of selenides 6
and 7 by chromatography on silica gel resulted in mixtures of products.
22. Bis(2-butoxy-2-chloroethyl) selenide (12), yield: 82% (dr = 1:1). 1H NMR
(400 MHz, CDCl3): d 0.95 (t, 6H, CH3, 3J = 7.2 Hz), 1.43 (m, 4H, CH2), 1.62 (m,
4H, CH2), 3.05 (m, 2H, SeCH2), 3.32 (m, 2H, SeCH2), 3.50 (m, 2H, OCH2), 3.90 (m,
2H, OCH2), 5.64 (m, 2H, OCHCl). 13C NMR (100.6 MHz, CDCl3): d 14.20 (CH3),
12. Typical procedure for the preparation of annulated products 1 and 4. A solution of
SeCl2 was prepared from Se (0.79 g, 10 mmol) and SO2Cl2 (1.35 g, 10 mmol) in
CHCl3 (20 ml). The solution of SeCl2 thus prepared and a solution of allyl
phenyl ether (1.34 g, 10 mmol) in CHCl3 (20 ml) were added separately and
simultaneously with stirring over 1 h to a flask containing CHCl3 (80 ml) cooled
to À60 °C. The cooling bath was removed and the mixture was allowed to
warm to room temperature with stirring and then heated at reflux for 5 h. The
solvent was evaporated and the crude product was purified by
chromatography on a short column of silica gel (eluent: hexane) to give
heterocycle 4 (2.21 g, 90% yield) as a yellow oil.
13. E-3-chloromethylene-2,3-dihydro-1,4-benzoxaselenine (1), yellow oil. 1H NMR
(400 MHz, CDCl3): d 4.39 (s, 2H, CH2O), 6.30 (s, 1H, =CHCl), 6.86–7.12 (m, 4H,
C6H4). 13C NMR (100.6 MHz, CDCl3): d 66.87 (OCH2), 113.97 (=CHCl), 115.01
1
19.16 (CH2), 31.31 (CH2), 33.01, 33.14 (SeCH2, JC–Se 70 Hz), 70.98 (CH2O),
98.01, 98.23 (OCHCl). Attempted purification of selenides 12–15 by
chromatography on silica gel resulted in their decomposition.
1
(C6H4, SeC, JSeC = 65 Hz), 119.25 (C6H4), 123.57 (C6H4), 126.94 (C6H4), 128.49
1
(C6H4), 131.40 (SeC=, JSeC = 100 Hz), 154.65 (C6H4,CO). 77Se NMR (76.3 MHz,
23. Bis(2-butoxy-2-bromoethyl) selenide (13), yield: 98% (dr = 1:1). 1H NMR
(400 MHz, CDCl3): d 0.98 (t, 6H, CH3, 3J = 7.2 Hz), 1.45 (m, 4H, CH2), 1.65 (m,
4H, CH2), 3.24 (m, 2H, SeCH2), 3.50 (m, 2H, OCH2), 3.64 (m, 2H, SeCH2), 3.86 (m,
2H, OCH2), 5.95 (m, 2H, OCHBr). 13C NMR (100.6 MHz, CDCl3): d 13.94 (CH3),
CDCl3): d 495. GC-MS: m/z (rel. intensity) 246 (66) [M]+Å, 211 (28) [M–Cl]+, 183
(10) [M–C2H4Cl]+, 166 (84) [M–Se]+Å, 144 (70) [M–OSeH2]+Å, 131 (100) [OSeCl]+,
118 (35) [SeC3H2]+Å, 91 (12) [PhCH2]+, 63 (92) [C2H4Cl]+, 50 (25) [CH3Cl]+Å. Anal.
Calcd for C9H7OClSe: C, 44.02; H, 2.87; Cl, 14.44; Se 32.15. Found: C, 43.67; H,
2.69; Cl, 14.82; Se, 31.87.
1
19.35 (CH2), 30.77 (CH2), 33.37, 33.68 (SeCH2, JC–Se 70 Hz), 72.24 (CH2O),
93.81, 94.12 (OCHBr).

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V. A. Potapov et al. / Tetrahedron Letters 52 (2011) 4606–4610
24. Bis(2-isobutoxy-2-chloroethyl) selenide (14), yield: 80% (dr = 1:1). 1H NMR
(400 MHz, CDCl3): d 0.99 (d, 12H, CH3, 3J = 6.2 Hz), 1.96 (m, 2H, CH), 3.30 (m,
2H, SeCH2), 3.40 (m, 4H, OCH2), 3.65 (m, 2H, SeCH2), 5.63 (m, 2H, OCHCl). 13C
NMR (100.6 MHz, CDCl3): d 19.49 (CH3), 28.12 (CH), 32.85 (SeCH2, 1JC–Se 70 Hz),
76.92 (CH2O), 97.80, 98.02 (OCHCl).
26. (a) Needleman, S. B.; Chang Kuo, M. C. Chem. Rev. 1962, 62, 405; (b)
Shostakovskii, M. F.; Bogdanova, A. V.; Volkov, A. N. Russ. Chem. Bull. 1961,
10, 1930.
27. We found that the reactions of selenium dichloride and dibromide with
styrene led to 1,2-dihaloethylbenzenes.
28. Luthra, N. D.; Odom, J. D. In The Chemistry of Organic Selenium and Tellurium
Compounds; Rappoport, Z., Patai, S., Eds.; John Wiley: New York, 1986; Vol. 1, p
189.
25. Bis(2-isobutoxy-2-bromoethyl) selenide (15), yield: 93% (dr = 1:1). 1H NMR
(400 MHz, CDCl3): d 0.99 (d, 12H, CH3, 3J = 6.2 Hz), 1.98 (m, 2H, CH), 3.29 (m,
2H, SeCH2), 3.41 (m, 4H, OCH2), 3.65 (m, 2H, SeCH2), 5.94 (m, 2H, OCHBr). 13C
NMR (100.6 MHz, CDCl3): d 19.53 (CH3), 27.94 (CH), 33.53, 33.63 (SeCH2, 1JC–Se
70 Hz), 79.19 (CH2O), 94.45, 94.75 (OCHCl).