Arylselenenation of conjugated dienes by arylselenenamides in the presence of phosphorus(V) oxyhalides

Article abstract of DOI:10.1016/j.tetlet.2006.09.168

Arylselenenation of conjugated and non-conjugated dienes by arylselenenamides in the presence of phosphorus(V) oxyhalides has been studied. Reactions with conjugated dienes lead to 1,4-adducts whilst only addition to double bonds takes place in reactions

Full text of DOI:10.1016/j.tetlet.2006.09.168

Tetrahedron Letters 48 (2007) 729–731
Arylselenenation of conjugated dienes by arylselenenamides in
the presence of phosphorus(V) oxyhalides
Roman L. Antipin,* Elena K. Beloglazkina, Nikolay V. Zyk and Nikolay S. Zefirov
Lomonosov Moscow State University, Chemistry Department, Leninskiye Gory 1, bld. 3 Moscow 119899, Russian Federation
Received 24 April 2006; revised 28 August 2006; accepted 7 September 2006
Available online 11 December 2006
Abstract—Arylselenenation of conjugated and non-conjugated dienes by arylselenenamides in the presence of phosphorus(V)
oxyhalides has been studied. Reactions with conjugated dienes lead to 1,4-adducts whilst only addition to double bonds takes place
in reactions with non-conjugated dienes.
Ó 2006 Elsevier Ltd. All rights reserved.
Arylselenenation reactions of unsaturated compounds
are of synthetic interest because the ‘selenation–desele-
nation’ sequence is a useful method for obtaining func-
tionally substituted alkenes.1–3 Selenenyl halide4–7 and
selenenyl triflate6 are used for the introduction of seleno-
containing moieties into alkenes and alkynes. The
products of such reactions are usually b-substituted
alkyl aryl selenides and are typically obtained in 65–
80% yields. However, this type of reaction is character-
ized by low regioselectivity (85:15).
under activation by POCl3 or SOCl2 resulted in the for-
mation of the 1,2-halosulphenyl- or selenenation prod-
ucts in good yields. The reaction mechanism involves
initial coordination of the phosphorus or sulfur Lewis
acid with the chalcogen atom of ArXNR2 (X = S, Se)
as based on NMR data.10
In this letter we report a simple and useful method for
the synthesis of substituted 1-arylseleno-4-halo-2-enes
by the reaction of conjugated dienes with arylselenen-
amides in the presence of phosphorus oxyhalides.
Electrophilic selenenation of dienes has not been inves-
tigated in detail. The only example of conjugated diene
selenenation in the literature involves reaction with phe-
nylselenenyl chloride giving either an allylic alcohol or
an enone depending on the experimental procedure.8
The initial products of the reaction of isoprene and
PhSeCl are regioisomeric chloroselenides, formed in
ratios from 1:1 to 2:5, depending on the reaction
temperature:
The reactions of 1 with dienes occur under mild condi-
tions (CH2Cl2, À30 °C)11 and products 2–7 are the
results of 1,4-addition (see Table 1).
The structures of the unsaturated haloselenides synthe-
sized were determined by NMR and IR spectroscopy.
1,4-Adducts were obtained in high yields in the case of
the reaction with conjugated dienes (see Table 1). The
structures of the 1,4-adducts were deduced as 2–7 based
on literature data on the products of analogous sulfenyl-
H
CH3
Cl
H
CH3
CH2SePh
H
CH3
+
3
ation reactions12–14 and (in the cases of 2, 3) Jtrans and
+
PhSeCl
coupling constants described for substituted cyclopent-
enes.15 Two isomeric 1,4-products, differing in the con-
figuration of the substituents around the C@C double
bond, were obtained from non-cyclic diene haloselene-
nation. The observed regioselectivity shows that the
direction of initial attack of the electrophile is
determined by electronic and not steric factors, as in
the reactions with isoprene, the electrophile preferably
adds to the C@C double bond adjacent to the donor
CH3-group.
ClCH2
CH2SePh
Earlier, we reported that the reaction of arylsulphen-
amides10 and diethylphenylselenenamide 19 with alkenes
*
Corresponding author. Fax: +7 495 939 0290; e-mail:
antipin@org.chem.msu.ru
0040-4039/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2006.09.168

730
R. L. Antipin et al. / Tetrahedron Letters 48 (2007) 729–731
O
P
O
P
+
Ar-X
Hal
Hal
Ar-X
Hal
Hal
ArXNR2
+ POHal3
NR2 Hal
NR2
Hal-
ArX
O
+
P
NR2
Hal
Hal
Hal
Table 1. Haloselenenation of conjugated dienes with arylselenenamide 1 and phosphorus oxyhalidesa,b
PhSeNEt2 (1)
PhSe
Hal (Hal = Cl, Br)
POHal3
Products
Diene
POHal3
POCl3
Ratio a:b
Yield (%)
52
Cl
PhSe
Cl
Br
PhSe
+
+
3/1
2a
3a
2b
3b
Br
PhSe
PhSe
POBr3
POCl3
POBr3
POCl3
POBr3
3/1
2/1
2/1
1/1
1/1
60
63
69
67
79
ClCH2
H
CH3
PhSeCH2
+
CH3
H
CH2SePh
CH2Cl
4a
4b
5b
BrCH2
H
CH3
PhSeCH2
+
CH3
H
CH2SePh
CH2Br
5a
6a
7a
ClCH2
CH3
CH3
PhSeCH2
CH2Cl
CH3
+
CH3
CH2SePh
6b
BrCH2
CH3
CH3
PhSeCH2
+
CH2SePh
CH3
CH3
CH2SePh
7b
a See Ref. 11 for typical reaction conditions.
b The ratios of the isomers were determined by NMR spectroscopy.
Reaction with conjugated dienes leads to 1,4-adducts,
but in the first step of the reaction the intermediate from
1,2-addition is formed, which is rapidly isomerized to
the 1,4-adduct. In the case of the addition to 1,3-cyclo-
pentadiene, the trans-isomer is the major product. This
can be explained through interaction of one of the lone
pairs of selenium with the carbocation centre, proceed-
ing at the 4-position of the cyclopentane ring, as has
previously been described.12
Hal
Se+
Ar
SeAr
Hal
ArSe
Hal-
Thus, POHal3-activated N,N-diethylphenylselenen-
amide 1 has been utilized for the haloselenenation of
dienes resulting in the formation of 1,4-haloselenenation
products in the case of conjugated dienes and mono-
Addition to only one double bond takes place in the case
of the reaction with non-conjugated dienes (see Table 2).

R. L. Antipin et al. / Tetrahedron Letters 48 (2007) 729–731
731
Table 2. Haloselenenation of non-conjugated dienes with arylselenenamide 1 and phosphorus oxyhalidesa
Diene
POHal3
Products
Ratio a:b
Yield (%)
SePh
Cl
POCl3
—
72
8
9
SePh
Br
POBr3
POCl3
—
76
SePh
Cl
+
1:5
75
Cl
SePh
10a
10b
a See Ref. 11 for typical reaction conditions.
9. Zyk, N. V.; Beloglazkina, E. K.; Antipin, R. L. Russ.
Chem. Bull 2004, 9, 2352 (Int. edition).
10. Zyk, N. V.; Beloglazkina, E. K.; Gazzaeva, R. A.; Tyurin,
V. S.; Titanyuk, I. D. Phosphorus, Sulfur, Silicon Relat.
Elem. 1999, 155, 33–45.
haloselenides in the case of non-conjugated dienes. The
simplicity of the experimental procedure and of product
purification makes this reaction a convenient method for
obtaining seleno-containing unsaturated compounds.
11. Typical reaction procedure: To a solution of N,N-dieth-
ylselenenamide 1 (2.5 mmol) in dry methylene chloride
(10 ml) at À30 °C, a solution of phosphorus(V) oxychlo-
ride (2.5 mmol) in CH2Cl2 (10 ml) was added. The
resulting mixture was stirred for 10 min and a solution
of diene (2.5 mmol) in the same solvent (10 ml) was added.
After 30 min, the temperature of the reaction mixture was
gradually raised to rt and the mixture was passed through
a short column of silica gel. Evaporation of the solvent in
vacuo gave the product of 1,4-addition as based on 1H
NMR data.
12. Schmid, G. H.; Yeroushalmi, S.; Garratt, D. G. J. Org.
Chem. 1980, 45, 910–915.
13. Hartke, K.; Jung, M. H.; Zerbe, H.; Kampchen, T. Liebigs
Ann. Chem. 1986, 1268–1280.
14. Hartke, K.; Gleim, H. U. Liebigs Ann. Chem. 1976, 716–
729.
15. Cocu, F. G.; Wolczunowicz, G.; Bors, L.; Posternak, Th.
Helv. Chim. Acta 1970, 53, 739–749.
References and notes
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1962, 2089–2099.
2. Back, T. G. Organoselenium Chemistry; Oxford University
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3599–3606.
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G. G. J. Org. Chem. 2002, 67, 4122–4126.
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67, 499–509.
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8. Brown, R. S.; Eyley, S. C.; Parsons, P. J. J. Chem. Soc.,
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