Copper-catalyzed chalcogenation of aryl iodides via reduction of chalcogen elements by aluminum or magnesium

Article abstract of DOI:10.1016/j.tet.2012.09.019

Aluminum-induced copper-catalyzed coupling of aryl iodides with selenium or sulfur element could afford the corresponding diaryl selenides or sulfides in good yields. When magnesium chloride as an additive was employed, diaryl monoselenides and monosulfides were selectively obtained. On the contrary, the use of sodium carbonate produced diaryl diselenides and disulfides. The preparation of diaryl diselenides was necessary for magnesium as a reductant. Regrettably, tellurium was very low reactivity.

Full text of DOI:10.1016/j.tet.2012.09.019

Tetrahedron 68 (2012) 10510e10515
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Copper-catalyzed chalcogenation of aryl iodides via reduction of chalcogen
elements by aluminum or magnesium
*
Nobukazu Taniguchi
Department of Chemistry, Fukushima Medical University, Fukushima 960-1295, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 22 June 2012
Received in revised form 30 August 2012
Accepted 4 September 2012
Available online 11 September 2012
Aluminum-induced copper-catalyzed coupling of aryl iodides with selenium or sulfur element could
afford the corresponding diaryl selenides or sulfides in good yields. When magnesium chloride as an
additive was employed, diaryl monoselenides and monosulfides were selectively obtained. On the
contrary, the use of sodium carbonate produced diaryl diselenides and disulfides. The preparation of
diaryl diselenides was necessary for magnesium as a reductant. Regrettably, tellurium was very low
reactivity.
Keywords:
Ó 2012 Elsevier Ltd. All rights reserved.
Chalcogenation
Aryl iodide
Chalcogen
Copper catalyst
Aluminum
1. Introduction
Reduction
m (metal)
Y
ArX
-mX
"Cu(I)-Y[m]"
Active
Cu(0) or Cu(I)
"Cu(II)Y"
Inactive
Cu(I)-YAr
Organochalcogenides are important compounds, and wide-
spread utilizations as reagents or intermediates are well known in
organic chemistry.1 These compounds have been prepared by var-
ious procedures so far. In particular, transition metal-catalyzed aryl
carbonechalcogen bond formations are convenient and useful
methods.2 These procedures have been usually performed by the
combination of chalcogenols or dichalcogenides with aryl halides.
Recently, many reactions are explored.3
However, a synthetic method by the combination of transition
metal catalysts with chalcogen elements has been very limited. A
few reactions have been reported to date.4 In general procedures,
chalcogens are often reduced by sodium or lithium at first step.5,6
The cause seems that the reactions of chalcogen elements with
transition metals provide stable and inactive complexes.7 Eventu-
ally, chalcogens are poisons of transition metals.
Scheme 1. A reaction of copper salts with chalcogen.
monochalcogenides and disulfides.9 Although diselenations did not
proceed in the presence of sodium carbonate, the use of magne-
sium as a reductant was able to promote the reaction. In this article,
I would like to present the full details of these reactions, including
their scope and limitation.
2. Result and discussions
To carry out chalcogenations of aryl iodides using chalcogens, I
initially investigated the selenation of 2-iodotoluene 1a in the
presence of CuI catalyst.
As an approach to solve this problem, I researched copper-
catalyzed reactions of chalcogens with aryl halides. From pre-
vious experiments, I found that the reduction of copper(II) chal-
cogenides produces copper(I) chalcogenides, and obtained
compounds could perform chalcogenations of aryl halides
(Scheme 1).8
As shown in Table 1, in the absence of the CuI catalyst or alu-
minum, the reaction could not proceed (entries 1 and 2). When the
combination of CuIebpy catalyst and aluminum powder was used,
di-2-tolyl selenide 2a and di-2-tolyl diselenide 3a were obtained in
75% and 6% yields, respectively (entry 3). But the employment of
other metals (Mg, Zn, Sm, and Sn) produced no satisfactory results
(entries 4e7).
Fortunately, the addition of magnesium chloride could selec-
tively synthesize 2a in 80% yield without the formation of 3a (entry
8). Sulfur is also available, and the production of monosulfide 2a
was 71% yield (entry 9).
Herein developed procedure was also possible to carry out the
coupling of aryl iodides with chalcogens, and afforded diaryl
* Tel./fax: þ81 24 547 1369; e-mail address: taniguti@fmu.ac.jp.
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2012.09.019

N. Taniguchi / Tetrahedron 68 (2012) 10510e10515
10511
Table 2
Copper-catalyzed monochalcogenations of aryl iodidesa
Table 1
Investigations of suitable conditionsa
CuI-bpy (10 mol%),
Al, MgCl2
Y (Se or S), additive
CuI-bpy (10 mol%)
Y
(ArY)2
Y=Se(3), S(5)
+
Ar
I
+
Y
Ar
Y=Se(2), S(4)
Ar
DMF, 110 °C
2-MeC6H4I
1a
(2-MeC6H4)2Y
Y=Se(2a),S(4a) Y=Se(3a),S(5a)
(2-MeC6H4)2Y2
+
1
DMF, 110 °C, 24 h
Entry
Y
ArI 1
Time (h) 2 or 4b (%) 3 or 5b (%) 1b (%)
1
2
3
4
5
6
7
8
Se 2-MeC6H4I (1a)
S
Se PhI (1b)
S
Se 4-MeC6H4I (1c)
S
Se 4-MeOC6H4I (1d)
S
Se 4-ClC6H4I (1e)
S
Se 4-BrC6H4I (1f)
S
Se 4-CF3C6H4I (1g)
Se 1-Naphthyl-I (1h) 18
S
24
19
24
22
24
43
24
45
24
45
40
40
24
80
71
78
75
79
62
77
73
77
76
70
43
74
85
79
0
0
0
0
0
0
5
0
0
0
0
0
Entry
Additive
Y
2a or 4ab (%)
3a or 5ab (%)
1ab (%)
1
None
Al
Al
Mg
Sm
Zn
Sn
Al, MgCl2
Al, MgCl2
Al
Al, Na2CO3
Al, Na2CO3
Mg, Na2CO3
Se
Se
Se
Se
Se
Se
Se
Se
S
S
S
Se
Se
0
0
75
32
64
0
0
0
6
15
0
0
0
0
0
94
93
5
2c
3
Trace
18
Trace
0
4
5
6
7
8
9
10
11d
12
13e
0
32
95
94
0
0
40
0
Trace
0
0
0
11
0
0
0
0
0
9
Trace
80
71
0
0
0
10
11
12
13
14
15
16c
0
0
0
0
0
0
0
35
92
0
92
0
Trace
79
44
18
a
Reaction conditions: The mixture 1a (0.3 mmol), Y (0.33 mmol), Al or Mg
(0.6 mmol), MgCl2 or Na2CO3 (0.15 mmol), and CuIebpy (1:1, 10 mol %) was treated
in DMF (0.5 mL).
Se 4-O2NC6H4I (1i)
a
Reaction conditions: The mixture 1 (0.3 mmol), Y (0.33 mmol), Al (0.6 mmol),
MgCl2 (0.15 mmol), and CuIebpy (1:1, 10 mol %) was treated in DMF (0.5 mL).
b
Isolated yields after silica gel chromatography.
CuI catalyst was not used.
CuI (15 mol %) was used.
4-MeC6H4I was employed instead of 2-MeC6H4I.
b
Isolated yields after silica gel chromatography.
Complex mixtures were obtained.
c
c
d
e
Table 3
Copper-catalyzed dichalcogenations of aryl iodides
On the contrary, when sodium carbonate was added in
the place of magnesium chloride, disulfide 5a was obtained
in 92% without the formation of monosulfide 4a (entry 11).
Regrettably, the procedure could not provide diselenide
(entry 12).
CuI-bpy,
Mg or Al,
Na2CO3
Ar
Y
Ar I
1
Ar2Y
Y=Se(2), S(4)
+
Y
Y
Ar
+
DMF, 110 °C
Y=Se(3), S(5)
In the synthesis of diselenide, the addition of magnesium in-
stead of aluminum was necessary, and the method afforded the
diselenide 5a in 79% yield (entry 13).
Similarly, other conditions were investigated. The employment
of copper-catalysts (CuCl, CuBr, CuOAc, CuCl2, and CuBr2), ligands
(1,10-phenanthroline, TMEDA, and PPh4) or solvents (PhCH3, DMA,
NMP, and DMI) were poor results.
On the basis of the described results, the copper-catalyzed
chalcogenation of aryl iodides using selenium or sulfur was un-
dertaken (Table 2). At first, preparations of diaryl mono-
Entry
Y
ArI 1
Time (h) 3 or 5c (%) 2 or 4c (%) 1c (%)
1a
Se 2-MeC6H4I (1a)
S
Se PhI (1b)
S
Se 4-MeC6H4I (1c)
S
Se 4-MeOC6H4I (1d) 18
S
Se 4-H2NC6H4I (1j)
S
Se 4-BrC6H4I(1f)
S
Se 4-ClC6H4I (1k)
65
24
65
45
65
45
9
92
75
85
79
82
69
72
39
75
15
16
14
0
0
0
0
0
8
0
7
2b
3a
Trace
0
Trace
Trace
0
Trace
Trace
Trace
15
4b
5a
6b
7a,d
8c
Trace
8
0
11
0
65
36
24
65
24
65
9b
10c
11a,e
12b,e
13a,e
chalcogenides
2
were screened. When
a mixture of ArI 1
(0.3 mmol), Se or
S
(0.3 mmol), CuIebpy (1:1, 10 mol %), Al
72
16
0
0
(0.6 mmol), and MgCl2 (0.15 mmol) in DMF (0.5 mL) was treated at
110 ꢀC, the procedure afforded the corresponding monoselenides 2
and sulfides 4 in 85e43% yield.
In these reactions, sulfur was slightly low reactive than sele-
nium. Regrettably, a reaction of aryl bromide or chloride did not
proceed at all.
Thus, the present method was possible to prepare symmetrical
diaryl monoselenides or monosulfides in nice yields and sup-
pressed the formation of dichalcogenides by the addition of mag-
nesium chloride.
I next inquired dichalcogenations of aryl iodides in the presence
of sodium carbonate (Table 3). In the disulfidation, a treatment of
ArI 1 (0.3 mmol), sulfur (0.6 mmol), CuIebpy (1:1, 15 mol %), Al
(0.6 mmol), and Na2CO3 (0.15 mmol) in DMF (0.5 mL) produced the
expected diaryl disulfides 5 in 92e16% yield. On the other hand, the
use of magnesium enabled the synthesis of diselenides 3 in 79e9%
yield.
a
Reaction conditions: The mixture 1a (0.3 mmol), Se (0.6 mmol), Mg (0.6 mmol),
Na2CO3 (0.15 mmol), and CuIebpy (1:1, 10 mol %) was used.
b
The mixture 1a (0.3 mmol), S (0.33 mmol), Al (0.6 mmol), Na2CO3 (0.15 mmol),
and CuIebpy (1:1, 15 mol %) was used.
c
Isolated yields after silica gel chromatography.
The reaction was carried out at 100 ꢀC.
Yields were determined by 1H NMR.
d
e
Surprisingly, in the diselenation conditions, when a reaction of
4-methoxyphenyl iodide was performed at 100 ꢀC for 65 h, the
methylselenation proceeded (Scheme 2).10 The corresponding
product 6 was obtained in 66% yield. Regrettably, other aryl iodides
were unavailable.
CuI-bpy (10 mol%),
Mg, Na2CO3
4-MeOC H4
SeMe
4-MeOC H4
I + Se
6
6
These diselenations were necessary for long reaction times than
disulfidations. Reactivities of dichalcogenations of aryl iodides
having electron-withdrawing groups decreased than other sub-
strates (entries 11e13).
DMF, 110 °C, 65 h
6
1d
66%
Scheme 2. Methylselenation of 4-MeOC6H4I.

10512
N. Taniguchi / Tetrahedron 68 (2012) 10510e10515
A synthesis of diaryl telluride was also examined. When the
dichalcogenides. These facts show that no monochalcogenations
proceed via formations of dichalcogenides.
condition using aluminum was carried out, the corresponding
diaryl tellurides could not be produced. Aryl iodides and tellurium
were recovered. However, the employment of magnesium as a re-
ductant afforded diphenyl telluride 7 in 25% yield with a trace
amount of ditelluride 8 (Scheme 3). Thus, the reactivity of tellurium
was very poor.
CuI-bpy (15 mol%),
Al,
MgCl2 or Na2CO3
+
Ph2Y
(PhY)2
1/2 (PhY)2
Y=Se(3b) or S(5b)
+
Ph-I
1b
DMF, 110 °C
18 h
2b or 4b 3b or 5b
Not detected
CuI-1,10-Phen (1:1, 10 mol%),
Mg (200 mol%)
(PhY)2: 84-91% recov.
ArI: 93-97% recov.
+
(PhTe)
8
+ Te
Ph I
1b
Ph2Te
7
2
DMF, 110 °C, 48 h
trace
Scheme 5. A reactivity of dichalcogenides in the presence of magnesium chloride or
sodium carbonate.
25%
Scheme 3. Copper-catalyzed monotellurilation of aryl iodides.
Finally, the sulfidation of 1a using Na2S$9H2O was checked.
When sulfur powder was added, disulfide 5a was obtained in 75%
yield, nevertheless the reaction excluding sulfur produced only
monosulfide 4a in 91% yield (Scheme 6). These results suggest that
the formation of Cu(I)SSNa is faster than Cu(I)SAr in the presence of
Na2CO3.5,12
To clear the reaction process, I then investigated the role of
copper and aluminum (Table 4). From various experiments, it was
obvious that the independent utilization of CuI or aluminum could
not promote the reaction (entries 1 and 2).11 In the absence of
aluminum, the addition of magnesium chloride showed same re-
sults (entries 3 and 4). Through the use of Cu(0) (200 mol %) pro-
duced 2a in 22% yield, the combination of Cu(0) (10 mol %) with
aluminum gave 2a in 91% yield (entries 5 and 6).
Na2S9H2O, S
CuI-bpy (15 mol%)
(2-MeC6H4S)2
5a
+
+
4a
DMF, 110 °C
trace
75%
Table 4
2-MeC6H4I
1a
Investigations of reaction mechanism
Na2S9H2O,
CuI-bpy (10 mol%)
Se, [Cu]
2-MeC6H4I
1a
(2-MeC H ) S
(2-MeC H ) Se
(2-MeC6H4Se)2
3a
+
5a
6
4 2
6
2a
4 2
DMF, 110 °C
DMF, 110 °C
4a
0%
91%
Entry
[Cu] (mol %)
Additive Time (h) 2aa (%) 3aa (%) 1aa (%)
Scheme 6. Reaction of sodium sulfide with 2-methylphenyl iodide.
1
2
3
4
5
6
7
8
Se
Se
Se
Se
Se
Se
None
Al
18
18
40
40
45
0
0
0
0
0
0
0
96
94
95
96
CuIebpy (10)
CuIebpy (10)
CuIebpy (200)
Cuebpy (200)
Cuebpy (10)
None
MgCl2
MgCl2
MgCl2
From these investigations, it is assumed that the formation of
monochalcogenides and dichalcogenides is an independent
process.
As shown in Fig. 1, a plausible mechanism is considered as fol-
lows. After the reaction of Cu(0) or CuI with chalcogen gives cop-
per(II) chalcogenide complexes, there are converted to copper(I)
chalcogenide 13 by the reduction of aluminum.13 Then, in dis-
elenation, a strong reductant such magnesium is required for the
acceleration of the reaction.
0
22
91
5
Trace 61
0
0
Al, MgCl2 30
0
90
0
None Cu(I)2Seebpy (100) Al, MgCl2 80
None Cu(II)Seebpy (100) Al, MgCl2 40
45
Trace
a
Isolated yields after silica gel chromatography.
A reactivity of copper-selenides was also surveyed. In the re-
action of Cu(I)2Se, the production of corresponding selenide was
lower yield. But, the case using Cu(II)Se afforded monoselenide 2a
in 45% yield (entries 7 and 8).
These results show that aluminum has no ability for the direct
reduction of selenium. The Cu(0) and Cu(I)-selenide species are
formed by the reduction of aluminum.
To examine the role of MgCl2 and Na2CO3, I carried out some
experiments. At first, a reactivity of PhYCu(I) 9 was researched.
When a mixture of PhYCu with iodobenzene was treated at 110 ꢀC,
the reaction gave only monochalcogenides without the production
of dichalcogenides (Scheme 4). These indicate dichalcogenations
cannot be synthesized after the formation of PhYCu.
On the other hand, the reaction of iodobenzene 1b with
dichalcogenide in the presence of MgCl2 or Na2CO3 could not give
monochalcogenides, and starting materials were recovered
(Scheme 5). Thus, these additives affected the reactions of
ArYAr
ArYYAr
Ar
Cu(I)ILn
10
Ar
[Cu]ILn
15
Y
LnI[Cu]
18
Al
ArY
YYAr
Cu(0)
11
CuIYn
12
Process
Process
B
A
1
Al
Y
1
LnCu(I)Y[M]
13
ArYCu(I)Ln
LnCu(I)YYAr
17
+
[M] = Mg2+
14
Y, [M] = Na
NaI
LnCu(I)YYNa
16
1
MgXI
Ar I
1
Process C
bpy
MgCl2 or Na2CO3
disproportionation
ArY
ArY
(PhY)2
3b or 5b
Not detected
+
PhYCu(I) PhI
Ph2Y
2b or 4b
71-80%
+
ArYCu(I)Ln
ArYYAr
Cu(II)Ln
19
14
DMF, 110 °C,
18 h
9
1b
11
Cu(0) 11
(Y=Se, S)
Scheme 4. A reactivity of phenylchalogenideecopper complex.
Fig. 1. Plausible reaction mechanism.

N. Taniguchi / Tetrahedron 68 (2012) 10510e10515
10513
As shown in the process A, in the presence of MgCl2, the in-
(67 MHz, CDCl3)
(51.3 MHz) d 410. Anal. Calcd for C14H14O2Se: C, 57.35; H, 4.81.
Found: C, 57.06; H, 4.65.
d
159.2, 134.6, 122.1, 114.9, 56.3; 77Se NMR
termediates 12 are formed from the reaction of 13 with ArI.14 Se-
quentially, diaryl monochalcogenide is produced.
On the other hand, dichalcogenations achieve in the presence of
Na2CO3. The additive depressed the reactivity and the formation of
monochalcogenides. Therefore, in the case of diselenation, the
employment of magnesium is necessary.
4.2.4. Di(4-chlorophenyl) selenide.17 1H NMR (270 MHz, CDCl3)
d
7.37 (d, J¼8.9 Hz, 4H), 7.25 (d, J¼8.4 Hz, 4H); 13C NMR (67 MHz,
CDCl3)
d 134.3, 133.3, 129.6, 129.4. Anal. Calcd for C124H8ClSe: C,
Eventually, two processes are considered. One way is that the
copperedisulfide complexes 16 generate from a reaction of 13 with
chalcogen, and diaryl disulfides 3 are produced (process B). Another
is that the complexes 14 produce dichalcogenide via dispropor-
tionation and reductive elimination when magnesium is used as
the reductant (process C).
47.72; H, 2.67. Found: C, 47.78; H, 2.69.
4.2.5. Di(4-bromophenyl) selenide. 1H NMR (270 MHz, CDCl3)
d 7.40
(d, J¼8.4 Hz, 4H), 7.30 (d, J¼8.4 Hz, 4H); 13C NMR (67 MHz, CDCl3)
d
134.6, 133.5, 132.6, 121.9; 77Se NMR (51.3 MHz)
d 432. Anal. Calcd
for C12H8Cl2Se: C, 36.87; H, 2.06. Found: C, 36.83; H, 2.15.
3. Conclusion
4.2.6. Di(4-trifluoromethylphenyl) selenide. 1H NMR (270 MHz,
CDCl3)
d d 135.1 (q,
7.59e7.53 (m, 8H); 13C NMR (67 MHz, CDCl3)
I achieved the copper-catalyzed synthesis of symmetrical diaryl
mono- or di-chalcogenides from aryl iodides with selenium or
sulfur by the addition of aluminum or magnesium. The employ-
ment of magnesium chloride could prepare diaryl mono-
chalcogenides, and the addition of sodium carbonate selectively
afforded dichalcogenides.
J¼1.1 Hz), 133.1, 130.0 (q, J¼32.9 Hz), 126.3 (q, J¼3.9 Hz), 123.9 (q,
J¼271.5 Hz); 77Se NMR (51.3 MHz)
d 443. Anal. Calcd for C14H8F6Se:
C, 45.55; H, 2.18. Found: C, 45.24; H, 2.20.
4.2.7. Di(1-naphthyl) selenide.18 1H NMR (270 MHz, CDCl3)
d
8.35e8.31 (m, 2H), 7.87e7.77 (m, 4H), 7.55e7.47 (m, 6H),
7.29e7.24 (m, 2H); 13C NMR (67 MHz, CDCl3)
d
134.1, 133.6, 132.2,
4. Experimental section
4.1. General
129.8, 128.6, 128.4, 127.1, 126.8, 126.3, 126.1. Anal. Calcd for
C20H14Se: C, 72.07; H, 4.23. Found: C, 72.11; H, 4.25.
4.2.8. Diphenyl sulfide.2a,4a 1H NMR (270 MHz, CDCl3)
(m, 10H); 13C NMR (67 MHz, CDCl3)
135.7, 131.0, 129.2, 127.0. Anal.
d 7.36e7.23
All reactions were carried out under nitrogen atmosphere. NMR
spectra were recorded on a JEOL EX-270 spectrometer (270 MHz for
d
Calcd for C12H10S: C, 77.37; H, 5.41. Found: C, 77.18; H, 5.49.
1H, 67.5 MHz for 13C). Chemical shifts are reported in
d
ppm refer-
enced to an internal tetramethylsilane standard for 1H NMR,
4.2.9. Di(2-methylphenyl) sulfide. 1H NMR (270 MHz, CDCl3)
chloroform-d (
d
77.0) for 13C NMR, and diphenyl diselenide (
d
480)
d d 138.9,
7.04e7.25 (m, 8H), 2.38 (s, 6H); 13C NMR (67 MHz, CDCl3)
for 77Se NMR. Elemental analysis was performed at the In-
strumental Analysis Center for Chemistry, Tohoku University
(Japan).
134.3, 131.1, 130.4, 127.1, 126.7, 20.1. Anal. Calcd for C14H14S: C,
78.45; H, 6.58. Found: C, 78.71; H, 6.61.
4.2.10. Di(4-methylphenyl) sulfide. 1H NMR (270 MHz, CDCl3)
d 7.35
4.2. Typical procedure for copper-catalyzed mono-
chalcogenation of aryl iodides (Table 2)
(d, J¼7.9 Hz, 4H), 7.07 (d, J¼7.9 Hz, 4H), 2.31 (s, 6H); 13C NMR
(67 MHz, CDCl3)
d 136.9, 132.6, 131.0, 129.9, 21.1. Anal. Calcd for
C14H14S: C, 78.45; H, 6.58. Found: C, 78.40; H, 6.52.
To a mixture of selenium (26.1 mg, 0.33 mmol), CuI (5.7 mg,
0.03 mmol), aluminum powder (53e150
mm) (16.2 mg, 0.6 mmol),
4.2.11. Di(4-methoxyphenyl) sulfide.2g 1H NMR (270 MHz, CDCl3)
d
MgCl2 (14.3 mg, 0.15 mmol), 2,20-bipyridyl (bpy) (4.6 mg,
0.03 mmol), and 2-iodotoluene 1a (65.4 mg, 0.3 mmol), DMF
(0.5 mL) was added, and the mixture was stirred at 110 ꢀC for 24 h.
After the reaction mixture was diluted with Et2O, the solution was
washed with H2O and saturated sodium chloride and dried over
anhydrous magnesium sulfate. Chromatography on silica gel
(hexane) gave di(2-methylphenyl) selenide (31.2 mg, 80%).15 1H
7.27 (d, J¼8.9 Hz, 4H), 6.82 (d, J¼8.9 Hz, 4H), 3.78 (s, 6H); 13C NMR
(67 MHz, CDCl3)
d 158.9, 132.7, 127.4, 114.8, 55.3. Anal. Calcd for
C14H14O2S: C, 68.26; H, 5.73. Found: C, 68.04; H, 5.70.
4.2.12. Di(4-chlorophenyl) sulfide. 1H NMR (270 MHz, CDCl3)
d
7.29e7.22 (m, 8H); 13C NMR (67 MHz, CDCl3)
d 133.9, 133.4, 132.3,
129.5. Anal. Calcd for C14H14SCl2: C, 56.48; H, 3.16. Found: C, 56.61;
H, 3.25.
NMR (270 MHz, CDCl3)
d
7.25e7.14 (m, 6H), 7.07e7.01 (m, 2H), 2.10
139.9, 133.2, 130.2, 127.5, 126.8,
(s, 6H); 13C NMR (67 MHz, CDCl3)
d
126.7, 22.2. Anal. Calcd for C14H14Se: C, 64.37; H, 5.40. Found: C,
64.21; H, 5.17.
4.2.13. Di(4-bromophenyl) sulfide. 1H NMR (270 MHz, CDCl3)
d 7.43
(d, J¼8.6 Hz, 4H), 7.18 (d, J¼8.9 Hz, 4H); 13C NMR (67 MHz, CDCl3)
d
134.5, 132.6, 132.4, 121.5. Anal. Calcd for C12H8Br2S: C, 41.89; H,
4.2.1. Diphenyl selenide.2f,4d 1H NMR (270 MHz, CDCl3)
(m, 6H), 7.26e7.24 (m, 4H); 13C NMR (67 MHz, CDCl3)
131.1, 132.9; 77Se NMR (51.3 MHz)
433. Anal. Calcd for C12H10Se: C,
d
7.47e7.44
2.34. Found: C, 41.55; H, 2.35.
d
127.2, 129.3,
d
4.2.14. Di(1-naphthyl) sulfide.4a 1H NMR (270 MHz, CDCl3)
61.81; H, 4.32. Found: C, 61.77; H, 4.35.
d
8.43e8.39 (m, 2H), 7.89e7.86 (m, 2H), 7.78e7.75 (m, 2H),
7.55e7.49 (m, 4H), 7.51e7.29 (m, 4H); 13C NMR (67 MHz, CDCl3)
134.1, 132.5, 132.4, 129.9, 128.6, 128.0, 126.7, 126.4, 125.9, 125.0.
4.2.2. Di(4-methylphenyl) selenide.16 1H NMR (270 MHz, CDCl3)
d
d
7.35 (d, J¼7.9 Hz, 4H), 7.07 (d, J¼7.9 Hz, 4H), 2.31 (s, 6H); 13C NMR
Anal. Calcd for C20H14S: C, 83.88; H, 4.93. Found: C, 83.47; H, 4.99.
(67 MHz, CDCl3)
(51.3 MHz)
d
137.2, 132.9, 130.1, 127.7, 21.1; 77Se NMR
d
418. Anal. Calcd for C14H14Se: C, 64.37; H, 5.40. Found:
4.3. Typical procedure for copper-catalyzed diselenation of
aryl iodides (Table 3)
C, 64.22; H, 5.16.
4.2.3. Di(4-methoxyphenyl) selenide.16 1H NMR (270 MHz, CDCl3)
d
To a mixture of selenium (47.4 mg, 0.6 mmol), CuI (5.7 mg,
0.03 mmol), magnesium powder (212e600 mm) (14.6 mg,
7.39 (d, J¼8.9 Hz, 4H), 6.79 (d, J¼8.9 Hz, 4H), 3.78 (s, 6H); 13C NMR

10514
N. Taniguchi / Tetrahedron 68 (2012) 10510e10515
0.6 mmol), Na2CO3 (31.8 mg, 0.3 mmol), bpy (4.7 mg, 0.03 mmol),
and DMF (0.5 mL) was added iodobenzene 1b (61.2 mg,
0.3 mmol), and the mixture was stirred at 110 ꢀC for 65 h. After
the reaction mixture was diluted with Et2O, the solution was
washed with H2O and saturated sodium chloride and dried over
anhydrous magnesium sulfate. Chromatography on silica gel
(hexane) gave diphenyl diselenide (35.0 mg, 75%).4c 1H NMR
(s, 3H); 13C NMR (67 MHz, CDCl3)
d 158.8, 133.4, 121.5, 114.8, 55.3,
8.71. Anal. Calcd for C8H10OSe: C, 47.77; H, 5.01. Found: C, 47.64; H,
4.68.
4.5. Data of diphenyl telluride (Scheme 3)
4.5.1. Diphenyl telluride.4b 1H NMR (270 MHz, CDCl3)
(m, 4H), 7.29e7.16 (m, 6H); 13C NMR (67.5 MHz, CDCl3)
d
7.70e7.67
137.9,
(270 MHz, CDCl3)
NMR (67 MHz, CDCl3)
(51.3 MHz) 480. Anal. Calcd for C12H12Se2: C, 46.18; H, 3.23.
d
7.62e7.59 (m, 4H), 7.27e7.24 (m, 6H); 13C
133.0, 131.5, 129.2, 12.7; 77Se NMR
d
d
129.4, 127.7, 114.6. Anal. Calcd for C12H10Te: C, 51.14; H, 3.58. Found:
C, 50.88; H, 3.68.
d
Found: C, 46.23; H, 3.44.
4.3.1. Bis(4-methylphenyl) diselenide.4b,c 1H NMR (270 MHz, CDCl3)
d
References and notes
7.50 (d, J¼8.2 Hz, 4H), 7.06 (d, J¼8.2 Hz, 4H), 2.33 (s, 6H); 13C NMR
1. (a) Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon:
New York, NY, 1991; Vol. 6; (b) Krief, A. In Comprehensive Organometallic
Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon: New
York, NY, 1995; Vol. 11; (c) Metzner, P.; Thuillier, A. In Sulfur Reagents in Organic
Synthesis; Katritzky, A. R., Meth-Cohn, O., Rees, C. W., Eds.; Academic Press: San
Diego, CA, 1994; (d) Organoselenium Chemistry; Wirth, T., Ed.; 208 Topics in
Current Chemistry; Springer: Heidelberg, 2000; Vol. 208; (e) Petragnani, N. In
Tellurium in Organic Synthesis; Katritzky, A. R., Meth-Cohn, O., Rees, C. W., Eds.;
Academic: San Diego, CA, 1994; (f) Kondo, T.; Mitsudo, T. Chem. Rev. 2000, 100,
3205; (g) Ley, S. L.; Thomas, A. W. Angew. Chem., Int. Ed. 2003, 42, 5400; (h)
Beletskaya, I. P.; Ananikov, P. V. Chem. Rev. 2011, 111, 1596; (i) Partyka, D. V.
Chem. Rev. 2011, 111, 1529.
(67 MHz, CDCl3)
d 138.0, 133.4, 132.3, 129.9, 21.1. Anal. Calcd for
C14H14Se2: C, 49.43; H, 4.15. Found: C, 49.83; H, 4.08.
4.3.2. Bis(4-methoxyphenyl) diselenide.4b,c 1H NMR (270 MHz,
CDCl3)
d
7.50 (d, J¼8.8 Hz, 4H), 6.80 (d, J¼8.8 Hz, 4H), 3.80 (s, 6H);
13C NMR (67 MHz, CDCl3)
d
160.0, 135.4, 121.9, 114.7, 55.3. Anal.
Calcd for C14H14O2Se2: C, 45.18; H, 3.79. Found: C, 44.80; H, 3.52.
4.3.3. Bis(4-aminophenyl) diselenide. 1H NMR (270 MHz, CDCl3)
d
7.37 (d, J¼8.5 Hz, 4H), 6.57 (d, J¼8.5 Hz, 4H), 3.76 (br, 4H); 13C
2. Selected paper: Pd-catalyzed reaction: (a) Migita, T.; Shimizu, T.; Asami,
Y.; Shiobara, J.; Kosugi, M. Bull. Chem. Soc. Jpn. 1980, 53, 1385; (b) Kosugi,
M.; Ogata, T.; Terada, M.; Sano, H.; Migita, T. Bull. Chem. Soc. Jpn. 1985, 58,
NMR (67 MHz, CDCl3)
d 147.0, 136.1, 119.4, 115.5. Anal. Calcd for
C14H12N2Se2: C, 42.12; H, 3.54. Found: C, 41.80; H, 3.51.
~
3657; (c) Baranano, D.; Hartwig, J. F. J. Am. Chem. Soc. 1995, 117, 2937; (d)
Ciattini, P. G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1995, 36, 4133; (e)
Zheng, N.; McWilliams, J. C.; Fleitz, F. J.; Armstrong, J. D., III; Volante, R. P.
J. Org. Chem. 1998, 63, 9606; (f) Nishiyama, Y.; Tokunaga, K.; Sonoda, N.
Org. Lett. 1999, 1, 1725; (g) Itoh, T.; Mase, T. Org. Lett. 2004, 6, 4587; Ni-
4.3.4. Typical procedure for copper-catalyzed disulfidation of aryl
iodides (Table 3). To a mixture of sulfur (10.6 mg, 0.3 mmol),
CuI (8.5 mg, 0.045 mmol), aluminum powder (53e150 mm)
catalyzed reaction: (h) Takagi, K. Chem. Lett. 1987, 2221; (i) Cristau, H. J.;
ˇ
Chabaud, B.; Chene, A.; Christol, H. Synthesis 1981, 892; (j) Millois, C.;
Diaz, P. Org. Lett. 2000, 2, 1705; (k) Taniguchi, N. J. Org. Chem. 2004, 69,
6904; Cu-catalyzed reaction: (l) Bowman, W. R.; Heaney, H.; Smith, P. H.
(16.2 mg, 0.6 mmol), Na2CO3 (15.9 mg, 0.15 mmol), bpy (7.0 mg,
0.045 mmol), and 2-iodotoluene 1a (65.4 mg, 0.3 mmol), DMF
(0.5 mL) was added, and the mixture was stirred at 110 ꢀC for 24 h.
After the reaction mixture was diluted with Et2O, the solution was
washed with H2O and saturated sodium chloride and dried over
anhydrous magnesium sulfate. Chromatography on silica gel
(hexane) gave di(2-methylphenyl) disulfide (34.0 mg, 92%). 1H NMR
ꢀ
G. Tetrahedron Lett. 1984, 25, 5821; (m) Palomo, C.; Oiarbide, M.; Lopez, R.;
ꢀ
Gomez-Bengta, E. Tetrahedron Lett. 2000, 41, 1283; (n) Kwong, F. Y.;
Buchwald, S. L. Org. Lett. 2002, 4, 3517.
3. (a) Xu, H. J.; Zhao, Y. Q.; Feng, T.; Feng, Y.-S. J. Org. Chem. 2012, 77, 2878; (b) Lin,
Y.-Y.; Wang, Y.-J.; Lin, C.-H.; Cheng, J.-H.; Lee, C.-F. J. Org. Chem. 2012, 77, 6100;
(c) Kumar, S.; Engman, L. J. Org. Chem. 2006, 71, 5400; (d) Wang, Z.; Mo, H.; Bao,
W. Synlett 2007, 91; (e) Akkilagunta, V. K.; Kakulapati, R. R. J. Org. Chem. 2011,
76, 6819; (f) Carril, M.; SanMartin, R.; Domínguez, E.; Tellititu, I. Chem.dEur. J.
2007, 13, 5100.
(270 MHz, CDCl3)
d
7.49e7.52 (m, 2H), 7.10e7.15 (m, 6H), 2.42 (s,
137.4, 135.4, 130.3, 128.7, 127.3,
6H); 13C NMR (67 MHz, CDCl3)
d
126.7, 20.0. Anal. Calcd for C14H14S2: C, 68.24; H, 5.73. Found: C,
68.19; H, 5.70.
4. (a) Jiang, Y.; Quin, Y.; Xie, S.; Zhang, X.; Dong, J.; Ma, D. Org. Lett. 2009, 11, 5250;
(b) Singh, D.; Deobald, A. M.; Camargo, L. R. S.; Tabarelli, G.; Rodrigues, O. E. D.;
Braga, A. L. Org. Lett. 2010, 12, 3288; (c) Balkrishna, S. J.; Bhakuni, B. S.; Chopra,
D.; Kumar, S. Org. Lett. 2010, 12, 5394; (d) Deng, H.; Li, Z.; Ke, F.; Zhou, X. Chem.
dEur. J. 2012, 18, 4840.
5. Reactions of aryl halides: (a) Rabai, J. Synthesis 1989, 523; (b) Syper, L.;
M1ochowski, J. Tetrahedron 1988, 44, 6119; (c) Detty, M. R.; Seidler, M. D. J. Org.
Chem. 1982, 47, 1354.
4.3.5. Diphenyl disulfide. 1H NMR (270 MHz, CDCl3)
4H), 7.33e7.19 (m, 6H); 13C NMR (67 MHz, CDCl3)
d
7.51e7.47 (m,
137.0, 129.1,
ꢀ
d
127.5, 127.1. Anal. Calcd for C12H10S2: C, 66.01; H, 4.62. Found: C,
66.04; H, 4.38.
6. Reactions of alkyl halides: (a) Gladysz, J. A.; Wong, V. K.; Jick, B. S. Tet-
€
€
rahedron 1979, 35, 2329; (b) Hase, T. A.; Perakyla, H. Synth. Commun. 1982,
12, 947; (c) Li, J. Q.; Bao, W. L.; Lue, P.; Zhou, X.-J. Synth. Commun. 1991, 21,
799.
4.3.6. Di(4-methylphenyl) disulfide. 1H NMR (270 MHz, CDCl3)
d
7.38 (d, J¼8.2 Hz, 4H), 7.10 (d, J¼8.2 Hz, 4H), 2.31 (s, 6H); 13C NMR
7. For selected examples of the cleavage of dichalcogenides bond by transition
metals: (a) Zanella, R.; Ros, R.; Graziani, M. Inorg. Chem. 1973, 12, 2736; (b)
Kumar, R.; Mabrouk, H. E.; Tuck, D. G. J. Chem. Soc., Dalton Trans. 1988, 1045; (c)
Mashima, K.; Nakayama, Y.; Kanehisa, N.; Kai, Y.; Nakamura, A. J. Chem. Soc.,
Chem. Commun. 1993, 1847; (d) Beletskaya, I.; Moberg, C. Chem. Rev. 1999, 99,
3435.
8. (a) Taniguchi, N.; Onami, T. Synlett 2003, 829; (b) Taniguchi, N.; Onami, T. J. Org.
Chem. 2004, 69, 915.
9. Taniguchi, N. Synlett 2005, 1687.
(67 MHz, CDCl3)
d 137.4, 133.8, 129.8, 128.5, 21.0. Anal. Calcd for
C14H14S2: C, 68.24; H, 5.73. Found: C, 68.10; H, 5.74.
4.3.7. Di(4-methoxyphenyl) disulfide. 1H NMR (270 MHz, CDCl3)
d
7.39 (d, J¼8.9 Hz, 4H), 6.83 (d, J¼8.9 Hz, 4H), 3.80 (s, 6H); 13C NMR
(67 MHz, CDCl3)
d 159.9, 132.7, 128.4, 114.6, 55.3. Anal. Calcd for
C14H14O2S2: C, 60.40; H, 5.70. Found: C, 60.40; H, 5.35.
10. It is considered that after the formation of ArSeCHO by
a reaction of
ArSeMg with DMF, it is reduced to ArSeCH3 by magnesium or selenium.
(a) Sevrin, M.; VanEnde, D.; Krief, A. Tetrahedron Lett. 1976, 2643; (b)
Nishiyama, Y.; Hamanaka, S.; Ogawa, A.; Kambe, N.; Sonoda, N. J. Org.
Chem. 1988, 53, 1326; (c) Lucchetti, J.; Krief, A. Tetrahedron Lett. 1981, 22,
1623.
4.3.8. Di(4-aminophenyl) disulfide. 1H NMR (270 MHz, CDCl3)
d 7.25
(d, J¼8.6 Hz, 4H), 6.58 (d, J¼8.6 Hz, 4H), 3.76 (s, 6H); 13C NMR
(67 MHz, CDCl3)
d 147.0, 133.9, 125.7, 115.3. Anal. Calcd for
11. In these reactions, selenium was recovered.
C14H12N2S2: C, 58.03; H, 4.87. Found: C, 58.08; H, 4.79.
12. The preparation of M2S2 (M¼Na or Li) can be performed by the reaction of
M2S with S at 90 ꢀC. The compounds can be used for the disulfidation of
alkyl halide. (a) Miller, E.; Crossley, F. S.; Moore, M. L. J. Am. Chem. Soc. 1942,
64, 2322.
13. The reactions of sulfur and selenium with copper salts generally afford com-
plicated copper chalcogenide complexes. (a) Higashi, L. S.; Lundeen, M.; Hilti,
E.; Seff, K. Inorg. Chem. 1977, 16, 310; (b) Kadooka, M. M.; Warner, L. G.; Sefff, K.
4.4. Data of 4-methoxyphenyl methyl selenide (Scheme 2)
4.4.1. 4-Methoxyphenyl methyl selenide. 1H NMR (270 MHz, CDCl3)
d
7.42 (d, J¼8.8 Hz, 2H), 6.83 (d, J¼8.8 Hz, 2H), 3.79 (s, 3H), 2.31

N. Taniguchi / Tetrahedron 68 (2012) 10510e10515
10515
J. Am. Chem. Soc. 1976, 7569; (c) Charbonnier, M.; Murat, M. Mater. Res. Bull.
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1973, 8, 1305.
17. Gaham, J. C.; Feng, C.-H.; Orticochea, M.; Ahmed, G. J. Org. Chem. 1990, 55,
14. Organic Syntheses; John Wiley & Sons: New York, NY, 1973; Collect. Vol. 5; p 107.
15. Sanjio, S. Z.; Snigdha, P.; Harkesh, B.; Gotthelf, W. Tetrahedron Lett. 2005,
46, 665.
4102.
18. Kumar, A. V.; Reddy, V. P.; Reddy, C. S.; Rao, R. K. Tetrahedron Lett. 2011, 52,
3978.