B. Movassagh – A. Fazeli · Zinc-Mediated Synthesis of Diaryl Selenides
195
Table 1. Synthesis of diaryl se-
lenides from diselenides and
diaryliodonium salts in the
presence of Zn/AlCl3.
Ar
Ar’2I+ X−
Reaction
time (h)
Yield
(%)a
M.p. or b.p.† (◦C)/Torr
found
reportedb
Ph
Ph
Ph
Ph
Ph2I+ I−
0.3
2
3.5
3
1.2
2.3
1.25
1.5
3
78
80
70
68
80
82
69
75
73
52
Oil
Oil12
(4-MeC6H4)2I+ I−
(4-ClC6H4)2I+ Cl−
(4-BrC6H4)2I+ Cl−
Ph2I+ I−
97 – 98†
139 – 141†
150 – 152†
139 – 141†
67 – 69
1006b
145 – 1506b
158 – 1616b
145 – 1506b
71 – 7313
103 – 1046b
100 – 1026b
129 – 1346b
240/0.27
a
Yields of pure isolated products;
references for physical data of
b
4-ClC6H4
4-ClC6H4
4-ClC6H4
3-MeC6H4
3-MeC6H4
1-Naphthyl
(4-MeC6H4)2I+ I−
(4-BrC6H4)2I+ Cl−
Ph2I+ I−
(4-MeC6H4)2I+ I−
Ph2I+ I−
products.
98 – 100
98 – 100†
126 – 128†
Oil
3.5
recorded using a Bruker AQS-300 Avance spectrometer. IR
spectra were obtained using a Shimadzu IR-460 spectropho-
tometer. Boiling points and melting points were determined
with a Bu¨chi B-540 melting point/boiling point capillary ap-
paratus.
Scheme 1.
matic systems [17]. The reaction is found to be gen-
eral and suitable for synthesis of both symmetric and
unsymmetric diaryl selenides. Various diaryliodonium
salts containing different substituents such as chloro,
methyl, bromo and two anions, chloride and bromide,
are successfully reacted.
General experimental procedure
A
mixture of diselenide (0.64 mmol), zinc dust
(5.12 mmol), anhydrous aluminum chloride (1.92 mmol) and
acetonitrile (20 ml) was stirred at 83 C for 2 h until the
◦
zinc powder had almost disappeared; diaryliodonium salt
(1.6 mmol) and water (4 ml) were then added at once to the
solution and stirring was continued at that temperature for
the appropriate time (Table 1) in air atmosphere. After com-
pletion of the reaction, the solution was filtered and washed
with diethyl ether. The combined Et2O/CH3CN solution was
then washed with water (3 × 20 ml), and the organic layer
was dried over anhydrous sodium sulfate. The solvent was
evaporated in vacuo to give the corresponding selenide which
was purified by preparative TLC (silica gel, eluent n-hexane :
ethyl acetate = 30:1).
Conclusion
In conclusion, we have developed a new general and
efficient procedure for the synthesis of various diaryl
selenides. The present method has the advantages of
operational simplicity, mild reaction conditions, lack
of toxicity, fast reaction rates, and low costs.
Experimental Section
Acknowledgements
Diaryliodonium salts were prepared by standard proce-
dures [18]. All products were characterized by comparison
The financial assistance of the K. N. Toosi University of
of their spectral and physical data with those of known sam- Technology Research Council and Kermanshah Oil Refining
1
ples. H (300 MHz) and 13C (75 MHz) NMR spectra were Company is gratefully acknowledged.
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