Formation of carbon-sulfur and carbon-selenium bonds by palladium-catalyzed decarboxylative cross-couplings of hindered 2,6-dialkoxybenzoic acids

Article abstract of DOI:10.1021/jo200344w

A simple route to diaryl sulfides using a decarboxylative palladium-catalyzed reaction between electron-rich 2,6-dialkoxybenzoic acid derivatives and diaryl disulfides is reported. This coupling proceeds efficiently in the presence of Pd(CF₃CO<

Full text of DOI:10.1021/jo200344w

NOTE
pubs.acs.org/joc
Formation of CarbonꢀSulfur and CarbonꢀSelenium Bonds by
Palladium-Catalyzed Decarboxylative Cross-Couplings of Hindered
2,6-Dialkoxybenzoic Acids
Jean-Michel Becht* and Claude Le Drian
Universitꢀe de Haute Alsace, Institut de Science des Matꢀeriaux de Mulhouse, LRC-CNRS 7228, 15 rue Jean Starcky,
F-68057 Mulhouse Cedex, France
S Supporting Information
b
ABSTRACT: A simple route to diaryl sulfides using a decarbox-
ylative palladium-catalyzed reaction between electron-rich 2,6-dia-
lkoxybenzoic acid derivatives and diaryl disulfides is reported. This
coupling proceeds efficiently in the presence of Pd(CF3CO2)2 and
Ag2CO3 in a 65:1 mixture of 1,4-dioxane and tetramethylene
sulfoxide (TMSO). We present also the first formation of a
carbonꢀselenium bond via a palladium-catalyzed decarboxylative
cross-coupling.
alladium-catalyzed cross-couplings offer one of the most
powerful routes for the formation of bonds between two
At the outset, we used experimental conditions analogous to
those of our previous work,26,27 and Table 1 presents the
optimization experiments. It turned out that PdCl2 was the most
active catalyst and afforded 2a in 53% yield (entry 2). No
improvement was achieved by increasing the reaction time or
P
sp2 carbons with high yields under mild reaction conditions.1,2
Extensive work has been devoted during the past decade to
develop related methodologies for the creation of bonds between
a sp2 carbon and a nitrogen3,4 or, very recently, an oxygen
atom.5,6 The formation of a bond between a sp2 carbon and a
sulfur atom has received less attention, despite the important
pharmaceutical properties of many aryl sulfides as potent drugs
for the treatment of inflammation,7 cancer,8 immunodeficiency
virus (HIV),9 and Alzheimer’s and Parkinson’s diseases.10,11
These sulfides were traditionally prepared via aromatic nucleo-
philic substitutions of activated chloroarenes with thiolates.12
Recently, several groups have reported mild and efficient condi-
tions for the formation of diaryl sulfides by couplings of aryl
halides with aryl thiols in the presence of copper,13 pal-
ladium,14,15 nickel,16 cobalt,17 iron,18 or indium catalysts.19,20
Diaryl sulfides have also been prepared via copper-catalyzed
reactions of unfunctionalized arenes with diaryl disulfides, but
only simple target molecules can be obtained by this method.21
Very recently, the easily available arenecarboxylic acids have
emerged as promising reagents for the formation of a bond
between an aryl carbon and a sp2 carbon via decarboxylative
cross-couplings22,23 but the formation of carbonꢀsulfur bonds
by this method was only very recently reported: the palladium-
copper-catalyzed decarboxylative cross-coupling between a
2-substituted arenecarboxylic acid and a thiol or a disulfide24
afforded good yields only in the presence of an electron-with-
drawing group on the arenecarboxylic acid.25 We have recently
published the palladium-catalyzed formation of arylꢀaryl bonds
from an arenecarboxylic acid and an aryl iodide26 or a diaryl
iodonium triflate.27 We present here a simple and efficient route
to diaryl sulfides from hindered electron-rich 2,6-disubstituted
arenecarboxylic acids.
23a
the amounts of catalyst or Ag2CO3 or by performing the
reaction in anhydrous conditions under an oxygen atmosphere or
in the presence of molecular sieves. The replacement of diphenyl
disulfide by thiophenol (1.1 equiv) gave 2a in <30% yield. Apart
from Pd(CF3CO2)2, which gave results similar to those obtained
with PdCl2, other Pd(II) or Pd(0) catalysts gave 2a in poor yields
(entries 3ꢀ9). Performing the coupling with PdCl2 in the pres-
ence of various ligands,28 or in a 9:1 mixture of DMF/DMSO,23e
afforded 2a in <50% yield (entries 10ꢀ17). Replacing PdCl2 with
Ni(acac)2, NiCl2(PPh3)2, or CuI gave 1,3-dimethoxybenzene as
the major product and only traces of 2a. Modification of the
order of addition of the reagents or replacement of Ag2CO3 by
other silver salts (Ag3PO4, AgOTf, AgOAc) by other bases
(Li2CO3, Cs2CO3, Et4NHCO3, CsF, or TMSOK) afforded 2a
in only much lower yields. In all cases of Table 1, even entry 1, it
should be noted that no starting material was present at the end
of the reaction and the only byproduct that could be isolated was
1,3-dimethoxybenzene. While our work was in progress, the
group of Su29 has reported an efficient direct arylation of indoles
with arenecarboxylic acids using Pd(CF3CO2)2, Ag2CO3, and
TMSO in refluxing 1,4-dioxane. Inspired by this report, the
coupling of 1a and diphenyl disulfide was performed with
Pd(CF3CO2)2 in a 65:1 mixture either of 1,4-dioxane/DMSO
or of 1,4-dioxane/TMSO. It turned out that 2a was obtained,
respectively, in improved 68% and 70% yields (entries 19 and
20). Use of 0.15 equiv of Pd(CF3CO2)2 gave 2a in a still good
Received: March 3, 2011
Published: June 20, 2011
r
2011 American Chemical Society
6327
dx.doi.org/10.1021/jo200344w J. Org. Chem. 2011, 76, 6327–6330
|

The Journal of Organic Chemistry
NOTE
Table 1. Determination of the Reaction Conditions
Table 2. Synthesis of Diaryl Sulfides
entry
catalyst
ligand
solvent
yielda (%)
1b
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
no reaction
2b,c
3b,c
4b,c
5b,c
6b,c
7b,c
8b,c
9b,c
PdCl2
53
<10
25
49
34
49
35
<10
25
17
47
27
40
30
15
40
64
entrya
R1
R2
R3
product
yieldb (%)
PdCl2(PPh3)2
PdCl2(PCy3)2
PdCl2(MeCN)2
Pd(OAc)2
1
Me
Me
iPr
H
H
H
H
2a
2b
2c
2d
2e
2f
75 (60)c
71 (65)c
68 (40)c
64 (51)c
58 (47)c
50 (39)c
51 (30)c
2
3d
OMe
H
4
Me
Me
Me
Me
H
4-Me
Pd(CF3CO2)2
Pd2(dba)3
5
H
4-OMe
4-Cl
6
H
Pd(PPh3)4
10bꢀd PdCl2
11bꢀd PdCl2
12bꢀd PdCl2
13bꢀd PdCl2
14bꢀd PdCl2
15b,c,e PdCl2
16b,c,e PdCl2
17b,c PdCl2
18f
19f
20f
21f
22f
AsPh3
7
H
4-NO2
2g
a Reaction conditions: arenecarboxylic acid (0.50 mmol, 1.0 equiv),
diaryl disulfide (1.1 equiv), Ag2CO3 (2.2 equiv), and Pd(CF3CO2)2
(0.3 equiv). b Isolated yields after flash chromatography of the crude
P(o-tolyl)3 DMSO
JohnPhos DMSO
DavePhos DMSO
tBu XPhos DMSO
DPEphos DMSO
c
reaction mixture on silica gel. Yield obtained in the presence of only
0.15 equiv of Pd(CF3CO2)2. d Reaction performed in the presence of 1.6
equiv of diphenyl disulfide.
DPPE
DMSO
DMF/DMSO 9:1
1,4-dioxane
Scheme 1. Structures of Arenecarboxylic Acids Used
Pd(CF3CO2)2
Pd(CF3CO2)2
Pd(CF3CO2)2
Pd(OAc)2
PdCl2
1,4-dioxane/DMSO 65:1 68
1,4-dioxane/TMSO 65:1 70g,h (60)i
1,4-dioxane/TMSO 65:1 22
1,4-dioxane/TMSO 65:1 31
a Calculated yields by 1H NMR of the crude reaction mixture. b Reaction
conditions: 2,6-dimethoxybenzoic acid (0.50 mmol, 1.0 equiv), diphenyl
disulfide (1.1 equiv), and Ag2CO3 (1.1 equiv) at 150 °C for 6 h.
c Reaction performed in the presence of a Pd catalyst (0.2 equiv).
d Reaction performed in the presence of 0.4 equiv of ligand. e Reaction
performed in the presence of 0.2 equiv of ligand. f Reaction conditions:
2,6-dimethoxybenzoic acid (0.50 mmol, 1.0 equiv), diphenyl disulfide
(1.1 equiv), Ag2CO3 (2.2 equiv), and Pd catalyst (0.2 equiv) at 100 °C
for 12 h. g Using only 0.5 equiv of diphenyl disulfide gave 2a in ca.
40% yield. h Performing the coupling with 1.1 equiv of Ag2CO3 afforded
2a in a lower 53% yield. i Coupling performed in the presence of
0.15 equiv of Pd catalyst. Using 0.1 equiv of Pd catalyst afforded 2a in
<30% yield. Using 0.3 equiv or 0.4 equiv of Pd catalyst gave 74ꢀ75%
yields (vide infra).
or electron-withdrawing groups gave the corresponding products
in 50ꢀ64% yields (entries 4ꢀ7).30 It is noteworthy that the use
of only 0.15 equiv of the palladium catalyst gave the desired
compounds in still acceptable yields (Table 2). As has already
been noted during the optimization studies, no starting material
was ever found at the end of the reaction, the only byproduct
being the decarboxylated arenes. The cross-couplings between
1a and 2,4-dimethoxybenzoic acid 1b0, 2,5-dimethoxybenzoic
acid 1c0, 2-nitro-4,5-dimethoxybenzoic acid 1d0, 2-nitrobenzoic
acid 1e0, pentafluorobenzoic acid 1f0, 2-fluoro-6-(pivalamido)-
benzoic acid 1g0, and 2-thiophenecarboxylic acid 1h were
unsuccessful (Scheme 1).
Finally, we used analogous conditions to obtain diaryl sele-
nides. These studies are still underway. The coupling of 1a with
diphenyl diselenide (Scheme 2) gave us the desired diaryl sel-
enide 3a in 62% isolated yield, whereas performing the reaction
with 1,2-bis(4-methylphenyl)diselenide or 1,2-bis(4-chlorophenyl)
diselenide31 afforded the corresponding diaryl selenides 3b and 3c,
60% yield (entry 20). No improvement was achieved by
replacement of Pd(CF3CO2)2 with Pd(OAc)2 or PdCl2 in these
conditions (entries 21 and 22). Finally, performing the coupling
in the presence of only 0.05 equiv of Ag2CO3 and 2.1 equiv of
Na2CO3 afforded 2a in a much lower yield of 36%. This shows
that a catalytic amount of the silver salt is not sufficient for the
reaction to proceed satisfactorily.
The scope and limitations of the reaction were then evaluated
(Table 2). The use of electron-rich 2,6-dimethoxybenzoic acid
and 2,4,6-trimethoxybenzoic acid afforded the desired diaryl
sulfides, respectively, in 75% and 71% yields using 0.3 equiv of
Pd(CF3CO2)2 (entries 1 and 2). Interestingly, the sterically
more hindered 2,6-diisopropoxybenzoic acid gave the corre-
sponding diaryl sulfide in a good 68% yield (entry 3). The
reaction of 1a with various diaryl disulfides bearing electron-donating
6328
dx.doi.org/10.1021/jo200344w |J. Org. Chem. 2011, 76, 6327–6330

The Journal of Organic Chemistry
NOTE
Scheme 2. Synthesis of a Diaryl Selenide
(d, 3J = 8.5 Hz, 2H), 6.98 (m, 4H), 7.36 (t, 3J = 8.5 Hz, 1H). 13C NMR
(80 MHz, CDCl3) δ (ppm): 20.9, 56.3, 104.3, 126.6, 129.3, 131.0, 134.4,
161.5. IR (CHCl3) ν (cmꢀ1) 3004, 2924, 1580, 1492, 1431, 1252, 1106.
HRMS: m/z calcd for C15H17O2S [M + H]+ 261.0944, found [M + H]+
261.0929.
1,3-Dimethoxy-2-((4-methoxyphenyl)thio)benzene (2e). Elution
with AcOEt/cyclohexane 15:85 afforded 93 mg (67% yield) of a
1
colorless oil. H NMR (400 MHz, CDCl3) δ (ppm): 3.75 (s, 3H),
3.83 (s, 6H), 6.62 (d, 3J = 8.3 Hz, 2H), 6.75 (d, 3J = 6.9 Hz, 2H), 7.12
(d, J = 6.9 Hz, 2H), 7.33 (t, J = 8.3 Hz, 1H). 13C NMR (80 MHz,
CDCl3) δ (ppm): 55.3, 56.3, 104.3, 114.2, 128.3, 129.4, 130.7, 157.7,
161.2. IR (CHCl3) ν (cmꢀ1) 3001, 2961, 2938, 1579, 1492, 1470, 1430,
1285, 1251, 1173, 1104, 1030. HRMS: m/z calcd for C15H17O3S
[M + H]+ 277.0893, found [M + H]+ 277.0891.
3
3
respectively, in 29% and 25% yields, whereas no reaction was
observed with dimethyl diselenide. To the best of our knowledge,
this cross-coupling represents the first reaction of formation of a
carbonꢀselenium bond from an arenecarboxylic acid.20,32
In conclusion, it should be noted that this carbonꢀsulfur
bond-forming reaction constitutes for arenecarboxylic acids
bearing electron-donating substituents a useful addition to the
method previously published by Liu and co-workers24 which
seems reserved to acids possessing electron-withdrawing
substituents.
1,3-Dimethoxy-2-((4-chlorophenyl)thio)benzene (2f). Elution with
AcOEt/cyclohexane 5:95 afforded 70 mg (50% yield) of a colorless oil.
1H NMR (400 MHz, CDCl3) δ (ppm): 3.83 (s, 6H), 6.65 (d, 3J = 8.6
Hz, 2H), 6.98 (d, 3J = 8.6 Hz, 2H), 7.13 (d, 3J = 8.6 Hz, 2H), 7.39 (t,
3J = 8.6 Hz, 1H). 13C NMR (80 MHz, CDCl3) δ (ppm): 56.3, 104.3,
107.0, 127.5, 128.6, 130.3, 131.3, 136.5, 161.4. IR (CHCl3) ν (cmꢀ1
)
3006, 2938, 1577, 1472, 1427, 1292, 1251, 1106, 1089, 1007. HRMS: m/
z calcd for C14H14ClO2S [M + H]+ 281.0403, found [M + H]+
281.0410.
’ EXPERIMENTAL SECTION
1,3-Dimethoxy-2-((4-nitrophenyl)thio)benzene (2g). Elution with
AcOEt/cyclohexane 1:9 afforded 74 mg (51% yield) of a yellow oil. 1H
NMR (400 MHz, CDCl3) δ (ppm): 3.84 (s, 6H), 6.69 (d, 3J = 8.3 Hz,
2H), 7.07 (d, 3J = 8.8 Hz, 2H), 7.47 (t, 3J = 8.3 Hz, 1H), 8.02 (d, 3J = 8.8
Hz, 2H). 13C NMR (80 MHz, CDCl3) δ (ppm): 56.3, 104.4, 123.7,
124.5, 126.3, 128.6, 132.4, 137.1, 144.7, 148.4, 161.4. IR (CHCl3) ν
(cmꢀ1) 3009, 2942, 1582, 1512, 1473, 1432, 1337, 1216, 1107, 1084.
HRMS: m/z calcd for C14H14NO4S [M + H]+ 292.0638, found
[M + H]+ 292.0634.
1,3-Dimethoxy-2-(phenylseleno)benzene (3a). Elution with AcOEt/
cyclohexane 5:95 afforded 91 mg (62% yield) of a colorless oil. 1H NMR
(400 MHz, CDCl3) δ (ppm): 3.80 (s, 6H), 6.63 (d, 3J = 8.3 Hz, 2H), 7.14
(m, 3H), 7.17 (m, 2H), 7.36 (t, 3J = 8.3 Hz, 1H). 13C NMR (80 MHz,
CDCl3) δ (ppm): 56.3, 104.3, 125.5, 128.6, 129.5, 131.0, 132.8, 145.8, 160.9.
IR (CHCl3) ν (cmꢀ1) 3000, 2959, 2931, 1724, 1581, 1469, 1430, 1249,
1105. HRMS: m/z calcd for C14H15O2Se [M + H]+ 295.0237, found
[M + H]+ 295.0240.
1,3-Dimethoxy-2-((4-methylphenyl)seleno)benzene (3b). Elution
with AcOEt/cyclohexane 5:95 afforded 44 mg (29% yield) of a colorless
oil. 1H NMR (400 MHz, CDCl3) δ (ppm): 2.27 (s, 3H), 3.79 (s, 6H),
6.61 (d, 3J = 8.6 Hz, 2H), 6.96 (d, 3J = 7.8 Hz, 2H), 7.17 (d, 3J = 7.8 Hz,
2H), 7.33 (t, 3J = 8.6 Hz, 1H). 13C NMR (80 MHz, CDCl3) δ (ppm):
21.0, 56.3, 104.3, 129.5, 130.1, 130.8, 135.4, 160.8. IR (CHCl3) ν
(cmꢀ1) 3001, 2919, 1583, 1489, 1439, 1242, 1101. HRMS: m/z calcd for
C15H17O2Se [M + H]+ 309.0394, found [M + H]+ 309.0391.
1,3-Dimethoxy-2-((4-chlorophenyl)seleno)benzene (3c). Elution
with AcOEt/cyclohexane 5:95 afforded 41 mg (25% yield) of a colorless
oil. 1H NMR (400 MHz, CDCl3) δ (ppm): 3.80 (s, 6H), 6.62 (d, 3J = 8.3
Hz, 2H), 7.14 (m, 4H), 7.37 (t, 3J = 8.3 Hz, 1H). 13C NMR (80 MHz,
CDCl3) δ (ppm): 56.3, 104.3, 105.9, 128.7, 130.9, 131.1, 131.2, 131.5,
160.7. IR (CHCl3) ν (cmꢀ1) 3004, 2935, 1580, 1478, 1427, 1290, 1251,
1101, 1094, 1009. HRMS: m/z calcd for C14H14ClO2Se [M + H]+
328.9848, found [M + H]+ 328.9851.
Synthesis of 1,3-Diisopropoxy-2-(phenylthio)benzene (2c). 1,4-Di-
oxane (8 mL) and TMSO (0.12 mL) were added to a mixture of the
diphenyl disulfide (0.8 mmol, 175 mg, 1.6 equiv), 2,6-diisopropoxybenzoic
acid (0.50 mmol, 119 mg, 1.0 equiv), Ag2CO3 (1.1 mmol, 303 mg,
2.2 equiv), and Pd(CF3CO2)2 (0.15 mmol, 50 mg, 0.3 equiv). The
reaction mixture was directly refluxed for 12 h. After being cooled to rt,
the reaction mixture was filtered with Celite, and the filtrate was
concentrated under vacuum. The residue was purified by flash
General Remarks. The reagents were obtained from commercial
sources and were used without further purification. 1,4-Dioxane was
purified by distillation under vacuum before use. Purifications of
compounds 2aꢀg and 3aꢀc were performed by flash chromatography
on silica gel (40ꢀ63 μm). 1H and 13C NMR spectra were recorded using
a 400 MHz instrument in CDCl3. Chemical shifts are reported in parts
per million (δ) downfield from TMS. Spin multiplicities are indicated
by the following symbols: s (singlet), d (doublet), t (triplet), hept
(heptuplet) and m (multiplet). 2,6-Diisopropoxybenzoic acid, 1,2-bis(4-
methylphenyl)diselenide, and 1,2-bis(4-chlorophenyl)diselenide were
prepared according to previous literature reports.31,33 HRMS spectra
were obtained by positive ESI ionization.
General Procedure for the Syntheses of Compounds
2aꢀb,dꢀg and 3aꢀc. 1,4-Dioxane (8 mL) and TMSO (0.12 mL)
were added to a mixture of the diaryl disulfide or diaryl diselenide
(0.55 mmol, 1.1 equiv), the arenecarboxylic acid (0.50 mmol, 1.0 equiv),
Ag2CO3 (1.1 mmol, 303 mg, 2.2 equiv), and Pd(CF3CO2)2 (0.15 mmol,
50 mg, 0.3 equiv). The reaction mixture was directly refluxed for 12 h.
After being cooled to rt, the reaction mixture was filtered with Celite and
the filtrate was concentrated under vacuum. The residue was purified by
flash chromatography on silica gel to afford pure reaction products after
drying under vacuum (0.1 mbar).
1,3-Dimethoxy-2-(phenylthio)benzene (2a). Elution with AcOEt/
cyclohexane 5:95 afforded 92 mg (75% yield) of a colorless oil. 1H NMR
(400 MHz, CDCl3) δ (ppm): 3.82 (s, 6H), 6.65 (d, 3J = 8.6 Hz, 2H),
3
7.06 (m, 3H), 7.17 (m, 2H), 7.38 (t, J = 8.6 Hz, 1H). 13C NMR
(80 MHz, CDCl3) δ (ppm): 56.3, 104.3, 107.4, 124.6, 126.1, 128.5,
131.2, 137.8, 161.5. IR (CHCl3) ν (cmꢀ1) 3069, 3003, 2940, 1582, 1471,
1430, 1291, 1252, 1086, 1024. HRMS: m/z calcd for C14H15O2S
[M + H]+ 247.0787, found [M + H]+ 247.0777.
1,3,5-Trimethoxy-2-(phenylthio)benzene (2b). Elution with AcOEt/
1
cyclohexane 15:85 afforded 98 mg (71% yield) of a colorless oil. H
NMR (400 MHz, CDCl3) δ (ppm): 3.82 (s, 6H), 3.88 (s, 3H), 6.23
(s, 2H), 7.04 (m, 3H), 7.16 (m, 2H). 13C NMR (80 MHz, CDCl3) δ
(ppm): 55.4, 56.3, 91.2, 124.3, 125.6, 128.5, 138.6, 162.5, 162.9. IR
(CHCl3) ν (cmꢀ1) 3059, 3004, 2964, 2939, 1580, 1467, 1456, 1339,
1227, 1205, 1124, 1094. HRMS: m/z calcd for C15H17O3S [M + H]+
277.0893, found [M + H]+ 277.0895.
1,3-Dimethoxy-2-((4-methylphenyl)thio)benzene (2d). Elution with
AcOEt/cyclohexane 5:95 afforded 83 mg (64% yield) of a colorless oil.
1H NMR (400 MHz, CDCl3) δ (ppm): 2.26 (s, 3H), 3.83 (s, 6H), 6.64
6329
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The Journal of Organic Chemistry
NOTE
chromatography on silica gel (elution with AcOEt/cyclohexane 5:95) to
afford 2c as a yellowish oil (103 mg, 68% yield) after drying under
vacuum
(14) Itoh, T.; Mase, T. Org. Lett. 2004, 6, 4587.
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(0.1 mbar). 1H NMR (400 MHz, CDCl3) δ (ppm): 1.20 (d, 3J = 6.0 Hz,
3
3
12H), 4.49 (hept, J = 6.0 Hz, 2H), 6.58 (d, J = 8.3 Hz, 2H), 7.05
(m, 1H), 7.14 (m, 4H), 7.23 (t, 3J = 8.3 Hz, 1H). 13C NMR (80 MHz,
CDCl3) δ (ppm): 21.9, 71.3, 107.1, 124.6, 127.5, 128.2, 129.9, 138.8,
159.8. IR (CHCl3) ν (cmꢀ1) 3072, 2977, 2930, 1582, 1457, 1250, 1115,
1059. HRMS: m/z calcd for C18H23O2S [M + H]+ 303.1419, found
[M + H]+ 303.1409.
(19) Reddy Prakash, V.; Swapna, K.; Vijay Kumar, A.; Rama Rao, K.
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(20) For a general review on transition-metal-catalyzed carbonꢀsulfur,
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’ ASSOCIATED CONTENT
Supporting Information. 1H and 13C NMR spectra for
S
b
products 2aꢀg and 3aꢀc. This material is available free of charge
via the Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION
(23) Reactions that combine decarboxylation of arenecarboxylic
acids with direct functionalization of CꢀH bonds for the synthesis of
biaryls follow a very similar concept: (a) Zhao, H.; Wei, Y.; Xu, J.; Kan, J.;
Su, W.; Hong, M. J. Org. Chem. 2011, 76, 882. (b) Wang, C.; Piel, I.;
Glorius, F. J. Am. Chem. Soc. 2009, 131, 4194. (c) Cornella, L.; Lu, P.;
Larrosa, I. Org. Lett. 2009, 11, 5506. (d) Zhang, F.; Greaney, M. Angew.
Chem., Int. Ed. 2010, 49, 2768. (e) Voutchkova, A.; Coplin, A.;
Leadbeater, N. E.; Crabtree, R. H. Chem. Commun. 2008, 6312.
(f) Xie, K.; Yang, Z.; Zhou, X.; Li, X.; Wang, S.; Tan, Z.; An, X.; Cuo,
C.-C. Org. Lett. 2010, 12, 1564.
Corresponding Author
*E-mail: jean-michel.becht@uha.fr.
’ ACKNOWLEDGMENT
We are grateful to the Centre National de la Recherche
Scientifique (CNRS) for financial support, to Dr. Didier Le
Nou€en (EA 4566) for NMR spectra, to Dr. Cꢀecile Joyeux
(EA 4566) for HRMS, and to Marc Furst for helpful technical
assistance.
(24) Duan, Z.; Ranjit, S.; Zhang, P.; Liu, X. Chem.—Eur. J. 2009,
15, 3666.
(25) A closely related synthesis of vinyl sulfides via a copper-
catalyzed decarboxylative reaction between arenepropiolic acids and
thiols has been reported and gave the expected products in good yields
even with arenepropiolic acids bearing electron-donating groups: Ranjit,
S.; Duan, Z.; Zhang, P.; Liu, X. Org. Lett. 2010, 12, 4134.
(26) Becht, J.-M.; Catala, C.; Le Drian, C.; Wagner, A. Org. Lett.
2007, 9, 1781.
(27) Becht, J.-M.; Le Drian, C. Org. Lett. 2008, 10, 3161.
(28) JohnPhos: 2-(di-tert-butylphosphino)biphenyl; DavePhos: 2-dicy-
clohexylphosphino-20-(N,N-dimethylamino)biphenyl; XPhos: 2-dicyclohex-
ylphosphino-20,40,60-triisopropylbiphenyl; DPEphos: bis[(2-diphenylpho-
sphino)phenyl] ether; DPPE: 1,2-bis(diphenylphosphino)ethane.
(29) Zhou, J.; Hu, P.; Zhang, M.; Huang, S.; Wang, M.; Su, W.
Chem.—Eur. J. 2010, 16, 5876.
(30) Reactions of 1a with dibenzyl, di-tert-butyl, or di-2-thienyl
disulfide were unsuccessful.
(31) Diaryl diselenides have been prepared via copper-catalyzed
reactions from the corresponding aryl iodides: Singh, D.; Deobald,
A. M.; Camargo, L. R. S.; Tabarelli, G.; Rodrigues, O. E. D.; Braga, A. L.
Org. Lett. 2010, 12, 3288.
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