Insertion of benzyne into a Bi-S bond: A new synthetic route to ortho -functionalized bismuthanes and its application to the synthesis of dibenzothiophene

Article abstract of DOI:10.1021/om200228x

ortho-Arylthio triarylbismuthanes [2-(Ar′S)C₆H ₄]_nBiAr_3-n have been conveniently synthesized by insertion of benzyne into the bismuth-sulfur bond of (Ar′S) _nBiAr_3-n (n = 1, 2). A similar insertion takes place when a homologous antimony congener is used, but no reaction is observed with its phosphorus analogue. This suggests a clear difference in the bond strength between pnictogen-sulfur bonds. The carbon-bismuth bond of [2-(2-BrC ₆H₄S)C₆H₄]_nBiAr _3-n undergoes Pd-catalyzed intramolecular cross-coupling to produce dibenzothiophene in good yield. An X-ray crystallographic study of 2-(2-BrC ₆H₄S)C₆H₄BiTol₂ (Tol = 4-MeC₆H₄) reveals that this molecule is present in a dimeric structure, where the six heteroatoms including bismuth, sulfur, and bromine are linked through the nonbonded intramolecular bismuth-sulfur and intermolecular sulfur-bromine and bromine-bromine interactions.

Full text of DOI:10.1021/om200228x

ARTICLE
pubs.acs.org/Organometallics
Insertion of Benzyne into a BiꢀS Bond: A New Synthetic Route to
ortho-Functionalized Bismuthanes and Its Application to the
Synthesis of Dibenzothiophene
Jing Chen and Toshihiro Murafuji*
Graduate School of Medicine, Yamaguchi University, Yamaguchi 753-8512, Japan
Ryo Tsunashima
Graduate School of Science and Engineering, Yamaguchi University, Yamaguchi 753-8512, Japan
S Supporting Information
b
ABSTRACT: ortho-Arylthio triarylbismuthanes [2-(Ar0S)C6-
H4]nBiAr3ꢀn have been conveniently synthesized by insertion
of benzyne into the bismuthꢀsulfur bond of (Ar0S)nBiAr3ꢀn
(n = 1, 2). A similar insertion takes place when a homologous
antimony congener is used, but no reaction is observed with its phosphorus analogue. This suggests a clear difference in the bond
strength between pnictogenꢀsulfur bonds. The carbonꢀbismuth bond of [2-(2-BrC6H4S)C6H4]nBiAr3ꢀn undergoes Pd-catalyzed
intramolecular cross-coupling to produce dibenzothiophene in good yield. An X-ray crystallographic study of 2-(2-BrC6-
H4S)C6H4BiTol2 (Tol = 4-MeC6H4) reveals that this molecule is present in a dimeric structure, where the six heteroatoms
including bismuth, sulfur, and bromine are linked through the nonbonded intramolecular bismuthꢀsulfur and intermolecular
sulfurꢀbromine and bromineꢀbromine interactions.
’ INTRODUCTION
’ RESULTS AND DISCUSSION
The insertion of benzyne into an elementꢀelement σ bond is
a powerful synthetic route to diverse polysubstituted arenes.1
Various σ bonds have been demonstrated to react with benzyne.
However, only a limited number of examples has been reported
on the insertion of arynes into a metalꢀelement bond.2 During
the course of our studies on the antifungal activity3a,b and phos-
phorescence3c of sulfur-functionalized organobismuth com-
pounds, we became interested in the possibility of applying the
reaction of benzyne to the construction of triarylbismuthanes.4
The most common method for preparing triarylbismuthanes is
the reaction of bismuth(III) halides with aryl-Grignard or aryl-
lithium reagents through halogenꢀmetal exchange or ortho-lithia-
tion of the parent arenes.5 However, the design and synthesis of
functionalized triarylbismuthanes is sometimes limited by the
compatibility of functional groups with reactive organometallic
reagents or lengthy synthesis of the parent haloarenes. Since a
bismuthꢀelement σ bond is reactive, insertion of benzyne into
this bond would be a new synthesis of ortho-functionalized
triarylbismuthanes. Herein, we describe the insertion of ben-
zyne into a bismuthꢀsulfur bond, which provides a conveni-
ent synthetic method for triarylbismuthanes that carry an
arylthio functional group ortho to the bismuth atom. Further-
more, this strategy is applied to the convenient and facile
synthesis of dibenzothiophene by combination with an in-
tramolecular cross-coupling reaction based on the synthetic
utility of triarylbismuthanes.
Synthesis of (Arylthio)bismuthanes and Their Reaction
with Benzyne. In order to investigate the reactivity of the
bismuthꢀsulfur bond toward benzyne, PhSBiTol2 1a was syn-
thesized from tris(4-methylphenyl)bismuthane (Tol3Bi) and
thiophenol in accordance with Scheme 1 (71% yield). We then
examined its reaction with benzyne, which was generated from
precursor 26 using a reported procedure2e (eq 1 and Table 1).
Initially, using 4 equiv of CsF to generate benzyne in THF did
not give adduct 3a (entry 1). However, when the solvent was
changed from THF to acetonitrile, we found that 3a was formed
in low yield (entry 2). Furthermore, increasing the amount of
CsF (5 equiv) dramatically improved the yield of 3a (entry 3).
The reaction was accelerated by further increasing the amount of
CsF to 6 equiv (entry 4), but a longer reaction time significantly
lowered the yield of 3a, probably due to its decomposition by
CsF (entry 5). These results indicate that the yield of 3a was
sensitive to the amount of CsF as well as to the nature of the
solvent employed. In contrast, an attempted reaction of Tol3Bi
with benzyne under similar conditions did not proceed. It is known
that triphenylphosphine reacts with benzyne to afford tetraphe-
nylphosphonium triflate.7
Following the successful formation of 3a from 1a in moderate
yield, substituted analogues 1 and 4 were synthesized in accordance
Received: March 15, 2011
Published: August 05, 2011
r
2011 American Chemical Society
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Scheme 1
Table 3. Effect of the ortho-Substituent
Table 1. Screening of the Synthesis of 3a
entry
substrate
2 (equiv)
time (h)
product
yield (%)
1
2
3
4
5
6
1a
1a
4a
4a
6a
6a
2
2
2
2
2
2
4
12
4
3a
3a
5a
5a
7a
7a
29
60
28
46
62
79
entry
CsF (equiv)
2 (equiv)
solvent
time (h)
3a yield (%)
12
4
1
2
3
4
5
4
4
5
6
6
2
2
2
2
2
THF
24
24
24
4
0
15
58
60
20
MeCN
MeCN
MeCN
MeCN
12
24
Scheme 2
Table 2. Reaction of Benzyne with 1 or 4
entry
2 (equiv)
substrate
product
yield (%) method Aa/ Bb
1
2
3
4
5
6
2
2
2
2
2
2
1a
1b
1c
4a
4b
4c
3a
3b
3c
5a
5b
5c
58/60
59/67
59/65
38/46
41/43
35/43
benzyne and that the reactivity of these compounds decreases in
the order of the substituent Me > H > Br (eq 3 and Table 3).
These results may be accounted for by the difference in the elec-
tronic effect between the electron-donating and -withdrawing nature
of the methyl and bromo substituents, respectively. In addition,
the greater steric bulk of the bromo substituent or its intramo-
lecular interaction with the bismuth atom10 may also block the
approach of benzyne to the bismuthꢀsulfur bond.
a CsF (5 equiv), MeCN, rt, 24 h. b KF (3 equiv), 18-crown-6 (3 equiv),
THF, 0 °C, 12 h.
with Scheme 1, and the substituent effect was studied through
their reaction with benzyne, which was generated using two
different methods (eq 2 and Table 2). The yields of the adducts 3
and 5 were improved by using KF and 18-crown-6 (method B),
compared to CsF (method A). The p-substituent of the aryl
group attached to the bismuth atom did not affect the yields of 3
and 5. In contrast, the bromo substituent adjacent to the sulfur
atom lowered the yield of 5 relative to 3. Although the yields of 5
are modest, it should be noted that 5 is easily obtained in one
simple step via benzyne. In contrast, its conventional synthesis
using an organolithium method requires not only the preparation
of the parent 2,20-dibromodiphenyl sulfide but also control the
sulfide’s subsequent regioselective halogenꢀmetal exchange.8
Bismuthanes 5aꢀc are considered to be highly useful as synthetic
precursors for the synthesis of dibenzothiophene by a Pd-catalyzed
cross-coupling reaction.4c,9
On this basis, the effect of the p-substituent on the arylthio
group was examined by synthesizing analogues 8a and 10a,
which bear an electron-donating and an electron-withdrawing
substituent, respectively (Scheme 2). Bismuthane 8a was highly
reactive, and it underwent a redistribution reaction to give Tol3Bi.
Although 8a could not be isolated in pure form, the reaction with
benzyne successfully afforded 9a. On the other hand, 10a easily
underwent a redistribution reaction to afford 10a0 along with
Tol3Bi. This is in contrast to the stability of 4a, which bears an
analogous bromo substituent at the ortho-position. Recently,
aromatic compounds persubstituted with sulfur ligands have at-
tracted much attention owing to their interesting physical organic
properties.11 In this context, benzyne inserted into both of the
bismuthꢀsulfur bonds of 10a0 to afford disulfurated bismuthane
11a. Furthermore, application of this insertion reaction to 12a,
14a, and 16a prepared from TolBiCl2 gave 13a, 15a, and 17a,
respectively (Scheme 3). The conjugated system of the 2-phe-
nylthiophenyl group in these derivatives is isoelectronic with that
In order to understand the effect of the arylthio group’s ortho-
substituent on its reactivity with benzyne, 6a, which bears a me-
thyl substituent, was synthesized. Unlike 1a and 4a, 6a was less
stable and slowly decomposed by a redistribution reaction to form
Tol3Bi. Comparison of the reactivity between 1a, 4a, and 6a
revealed that the methyl substituent promotes the insertion of
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Scheme 3
Scheme 4
Scheme 5
interaction with the sulfur atom. An intramolecular interaction of
this type between the bismuth and sulfur atoms may be respon-
sible for the unique and unexpected effect, stabilizing the bismuthꢀ
methyl bond of heterocyclic 10-methylphenothiabismine [ꢀBi-
(Me)C6H4SC6H4ꢀ] enough to make this compound isolable
and stable in air.8 Furthermore, the bromine atom is in close
proximity to the sulfur atom and appears to sterically block the
insertion of benzyne into the BiꢀS bond of 4a. The crystal
packing of 5a is also unusual (see Supporting Information): the
intermolecular atomic distances between the bromine atoms
(3.646 Å) and between the bromine and sulfur atoms (3.621 Å)
are both within the sum of the van der Waals radii (3.8 and 3.7 Å,
respectively), suggesting the existence of a weak interaction. These
interactions between molecules of 5a produce a dimeric struc-
ture, where the heteroatoms are coplanar with the phenylene ring
to which they are attached. Thus, the six heteroatoms, including
bismuth, sulfur, and bromine, are linked through weak interac-
tions. This kind of unusual interaction has been observed in
ortho-disubstituted benzenes and peri-substituted naphthalene and
anthracene.17 Intermolecular CHꢀπ interactions are present
between the H(9) and one of the tolyl groups [C(8)ꢀC(14)] at
the bismuth atom. This is reflected in the C(1)ꢀBi(1)ꢀC(8)
bond angle [96.28(9)°], which is forced to be larger than the
other bond angles around the bismuth atom.
of the styrylphenyl scaffold of the phosphorescent triarylbismu-
thane bearing an (E)-4-(4-tert-butylstyryl)phenyl group.12
To compare the difference in the reactivity between 1a and its
pnictogen counterparts, 18, 20, and 22 were synthesized and the
insertion of benzyne into the SbꢀS, AsꢀS, and PꢀS bonds was
examined (Scheme 4). Stibine 18 underwent insertion with ben-
zyne in a similar manner to 1a to give 19. However, when
arylthioarsine 2013a,b and arylthiophosphine 2213d were sub-
mitted to the same reaction conditions, the corresponding adducts
21 and 23 were not formed. Such difference in reactivity reflects
the stronger bond energy of the AsꢀS and PꢀS bonds compared
to the BiꢀS and SbꢀS bonds.14 Stibine 24, which bears two re-
action sites, smoothly underwent insertion with benzyne to give 25.
Cross-Coupling Reaction. Dibenzothiophenes have found
numerous applications as dyes, pharmaceuticals, and conducting
polymers.15 Recent growing interests in the synthetic utility of
triarylbismuthanes in palladium-catalyzed cross-coupling reactions4c,9
led us to synthesize dibenzothiophene from 5a and 15a via an
intramolecular cross-coupling reaction (Scheme 5). The reaction
proceeded smoothly to afford dibenzothiophene in 81% and 54%
yields, respectively. Although many methods have been reported
for the synthesis of dibenzothiophene,15,16 we expect this to
provide one of the most efficient synthetic routes, because of the
convenience and simplicity of the procedure.
In summary, the present method provides a novel approach to
the synthesis of sulfur-functionalized bismuthanes and stibines.
Furthermore, it is expected that this methodology will be ap-
plicable to the synthesis of functionalized bismuthanes that are
heteroatom-substituted at the ortho-position from precursors
bearing a bismuthꢀheteroatom σ bond. Further studies on the
synthetic application of this strategy are currently underway.
X-ray Crystallographic Study of 5a. The molecular structure
of a benzyne adduct was revealed by the X-ray crystallography of
5a (Figure 1 and Table 4). The S(1) atom is adjacent to both
Bi(1) and Br(1) atoms, and the S(1)ꢀC(21) bond is disposed in
a trans fashion toward the Bi(1)ꢀC(8) bond. The intramolecular
atomic distances of S(1) Bi(1) [3.397(2) Å] and S(1)
Br(1) [3.174(2) Å] are within the sum of the van der Waals radii
(4.2 and 3.7 Å, respectively),10a which indicates that the bismuth
atom forms a distorted tetrahedron10a through the intramolecular
’ EXPERIMENTAL SECTION
General Comments. All reactions were carried out under argon
unless otherwise noted. Acetonitrile, diethyl ether, methanol, and tetra-
3 3 3
3 3 3
hydrofuran were distilled from calcium hydride before use. 1H and 13
C
NMR spectra were recorded in CDCl3 or DMSO-d6 on a Bruker Avance
400S spectrometer with TMS as an internal standard.
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Figure 1. ORTEP drawing of the molecular structure of 5a with 50% probability ellipsoids.
extracts were dried over anhydrous sodium sulfate and evaporated to
leave a residue, which was chromatographed on silica gel with hexaneꢀ
ethyl acetate (5:1) to give the product.
Bis(4-methylphenyl)(phenylthio)bismuthane (1a): yellow
solid; yield 71%; mp 108ꢀ109 °C; 1H NMR (400 MHz, CDCl3)
δ 2.34 (6H, s), 7.08 (1H, t, J = 7.2 Hz), 7.15 (2H, t, J = 7.2 Hz), 7.36 (4H,
d, J = 7.6 Hz), 7.36 (2H, d, J = 7.2 Hz), 7.96 (4H, d, J = 7.6 Hz); 13C
NMR (100 MHz, CDCl3) δ 21.6, 126.3, 128.5, 132.2, 134.6, 135.9,
137.3, 138.2, 163.7. Anal. Calcd for C20H19BiS: C, 48.00; H, 3.83.
Found: C, 47.70; H, 3.86.
Diphenyl(phenylthio)bismuthane (1b): yellow solid; yield
70%; mp 83ꢀ84 °C (lit.4b 91.7ꢀ92.7 °C); 1H NMR (400 MHz,
CDCl3) δ 7.09 (1H, t, J = 7.2 Hz), 7.16 (2H, t, J = 7.2 Hz),
7.34ꢀ7.39 (4H, m), 7.56 (4H, t, J = 7.6 Hz), 8.08 (4H, d, J = 7.6
Hz); 13C NMR (100 MHz, CDCl3) δ 126.4, 128.4, 128.5, 131.4, 134.7,
135.5, 137.2, 167.2. Anal. Calcd for C18H15BiS: C, 45.77; H, 3.20.
Found: C, 45.80; H, 2.90.
Bis(4-chlorophenyl)(phenylthio)bismuthane (1c): yellow
solid; yield 66%; mp 94ꢀ95 °C; 1H NMR (400 MHz, CDCl3) δ 7.11
(1H, t, J = 7.2 Hz), 7.17 (2H, t, J = 7.2 Hz), 7.32 (2H, d, J = 7.2 Hz), 7.49
(4H, d, J = 8.4 Hz), 7.96 (4H, d, J = 8.4 Hz); 13C NMR (100 MHz,
CDCl3) δ 128.7, 130.9, 131.7, 134.5, 134.8, 138.6, 138.8, 152.8. Anal.
Calcd for C18H13BiCl2S: C, 39.94; H, 2.42. Found: C, 39.78; H, 2.34.
Bis(4-methylphenyl)(2-bromophenylthio)bismuthane
(4a): yellow solid; yield 57%; mp 144ꢀ145 °C; 1H NMR (400 MHz,
CDCl3) δ 2.34 (6H, s), 6.95 (1H, dt, J = 1.6, 7.6 Hz), 7.08 (1H, dt, J =
1.6, 7.6 Hz), 7.37 (4H, d, J = 7.6 Hz), 7.48 (1H, dd, J = 1.6, 7.6 Hz), 7.56
(1H, dd, J = 1.6, 7.6 Hz), 7.99 (4H, d, J = 7.6 Hz); 13C NMR (100 MHz,
DMSO-d6) δ 21.2, 126.7, 127.3, 131.2, 132.4, 133.1, 136.0, 136.8, 137.4,
138.9, 152.5. Anal. Calcd for C20H18BiBrS: C, 41.47; H, 3.13. Found: C,
41.76; H, 3.13.
Table 4. Selected Bond Lengths or Atomic Distances (Å) and
Angles (deg) for 5a
Bond Lengths
Intramolecular Atomic Distances
Bi(1)ꢀC(1)
2.261(2)
2.247(3)
2.283(2)
1.913(3)
1.800(3)
1.767(3)
1.394(3)
1.406(3)
1.376(4)
1.399(4)
1.390(3)
1.381(4)
Bi(1)•••S(1)
Br(1)•••S(1)
3.397(2)
3.174(2)
Bi(1)ꢀC(8)
Bi(1)ꢀC(15)
Br(1)ꢀC(26)
S(1)ꢀC(20)
S(1)ꢀC(21)
C(15)ꢀC(16)
C(15)ꢀC(20)
C(19)ꢀC(20)
C(21)ꢀC(22)
C(21)ꢀC(26)
C(25)ꢀC(26)
Intermolecular Atomic Distances
Br(1)•••S(1)
Br(1)•••Br(1)
3.621
3.646
Bond Angles
C(1)ꢀBi(1)ꢀC(8)
C(1)ꢀBi(1)ꢀC(15)
C(8)ꢀBi(1)ꢀC(15)
C(20)ꢀS(1)ꢀC(21)
C(20)ꢀC(15)ꢀBi(1)
S(1)ꢀC(20)ꢀC(15)
C(26)ꢀC(21)ꢀS(1)
96.28(9)
94.02(8)
92.97(9)
103.3(1)
119.5(2)
118.9(2)
117.9(2)
Synthesis of Diaryl(arylthio)bismuthanes. General Proce-
dure. A typical example is exemplified by the synthesis of 1a. To a
solution of thiophenol (3 mmol) in methanol (3 mL) was added sodium
methoxide (3.6 mmol) at room temperature, and the resulting solution
was stirred for 30 min. To this solution thus obtained was added drop-
wise a suspension of chlorobis(4-methylphenyl)bismuthane (3 mmol),
prepared from tris(4-methylphenyl)bismuthane (2 mmol) and bismuth-
(III) chloride (1 mmol) in diethyl ether (10 mL) by stirring for 1 h at
room temperature, and the reaction mixture was stirred for 2 h at room
temperature. The reaction was quenched with brine (10 mL), and the
mixture was extracted with ethyl acetate (10 mL ꢁ 3). The combined
Diphenyl(2-bromophenylthio)bismuthane (4b): yellow so-
lid; yield 52%; mp 82ꢀ83 °C; 1H NMR (400 MHz, CDCl3) δ 6.95 (1H,
dt, J = 1.6, 7.6 Hz), 7.09 (1H, dt, J = 1.6, 7.6 Hz), 7.36 (2H, t, J = 7.6 Hz),
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7.49 (1H, dd, J = 1.6, 7.6 Hz), 7.56 (4H, t, J = 7.6 Hz), 7.57 (1H, dd, J =
1.6, 7.6 Hz), 8.11 (4H, d, J = 7.6 Hz); 13C NMR (100 MHz, DMSO-d6)
δ 126.5, 127.6, 127.7, 128.6, 131.1, 132.6, 135.7, 137.7, 140.6, 173.5.
Anal. Calcd for C20H14BiBrS: C, 39.22; H, 2.56. Found: C, 39.19;
H, 2.41.
7.34 (1H, dt, J = 1.6, 7.6 Hz), 7.39 (1H, dt, J = 1.6, 7.6 Hz), 7.48 (1H, dd,
J = 1.6, 7.6 Hz), 7.55 (4H, d, J = 7.6 Hz), 7.63 (1H, dd, J = 1.6, 7.6 Hz),
7.88 (1H, dd, J = 1.6, 7.6 Hz); 13C NMR (100 MHz, CDCl3) δ 21.5,
121.2, 126.4, 127.6, 128.1, 129.4, 131.3, 131.9, 132.7, 136.4, 137.2, 137.6,
138.9, 139.4, 139.8, 154.5, 165.0. Anal. Calcd for C26H22BiBrS: C, 47.65;
H, 3.38. Found: C, 48.02; H, 3.44.
Diphenyl[2-(2-bromophenylthio)phenyl]bismuthane (5b):
colorless solid; yield 43%; mp 72ꢀ73 °C; 1H NMR (400 MHz, CDCl3)
δ 6.60 (1H, dd, J = 1.6, 7.6 Hz), 6.93 (1H, dt, J = 1.6, 7.6 Hz), 6.96 (1H,
dt, J = 1.6, 7.6 Hz), 7.29 (2H, t, J = 7.6 Hz), 7.36 (4H, t, J = 7.6 Hz), 7.36
(1H, dt, J = 1.6, 7.6 Hz), 7.41 (1H, dt, J = 1.6, 7.6 Hz), 7.48 (1H, dd, J =
1.6, 7.6 Hz), 7.66 (1H, dd, J = 1.6, 7.6 Hz), 7.67 (4H, d, J = 7.6 Hz), 7.87
(1H, dd, J = 1.6, 7.6 Hz); 13C NMR (100 MHz, CDCl3) δ 121.2, 126.5,
127.6 (ꢁ2), 128.2, 129.5, 130.5, 132.0, 132.7, 136.5, 137.5, 139.0, 139.5,
139.6, 158.4, 165.5. Anal. Calcd for C24H18BiBrS: C, 45.95; H, 2.89.
Found: C, 46.06; H, 2.88.
Bis(4-chlorophenyl)[2-(2-bromophenylthio)phenyl]bis-
muthane (5c): colorless solid; yield 43%; mp 105ꢀ106 °C; 1H NMR
(400 MHz, CDCl3) δ 6.51ꢀ6.54 (1H, m), 6.91ꢀ6.97 (2H, m), 7.29
(4H, d, J = 8.0 Hz), 7.35ꢀ7.47 (3H, m), 7.55 (4H, d, J = 8.0 Hz), 7.68
(1H, dd, J = 1.6, 7.6 Hz), 7.81 (1H, dd, J = 1.6, 7.6 Hz); 13C NMR (100
MHz, CDCl3) δ 121.2, 126.7, 127.7, 128.0, 129.8, 130.6, 132.3, 132.8,
134.0, 137.0, 138.8, 138.9, 139.1, 139.2, 156.0, 165.4. Anal. Calcd for
C24H16BiBrCl2S: C, 41.40; H, 2.32. Found: C, 41.79; H, 2.41.
Bis(4-methylphenyl)[2-(2-methylphenylthio)phenyl]bis-
muthane (7a): colorless solid; yield 79%; mp 111ꢀ112 °C; 1H NMR
(400 MHz, CDCl3) δ 2.32 (6H, s), 2.33 (3H, s), 6.89 (1H, dd, J = 1.2,
7.6 Hz), 6.99 (1H, dt, J = 1.2, 7.6 Hz), 7.07 (1H, dt, J = 1.2, 7.6 Hz), 7.16
(1H, dd, J = 1.2, 7.6 Hz), 7.17 (4H, d, J = 7.6 Hz), 7.23 (1H, dt, J = 1.6,
7.6 Hz), 7.30 (1H, dt, J = 1.6, 7.6 Hz), 7.43 (1H, dd, J = 1.6, 7.6 Hz), 7.57
(4H, d, J = 7.6 Hz), 7.79 (1H, dd, J = 1.6, 7.6 Hz); 13C NMR (100 MHz,
CDCl3) δ 20.5, 21.5, 126.3, 126.6, 129.1, 129.3, 130.2, 130.6, 131.3,
134.2, 136.7, 137.0, 137.2, 137.6, 139.1, 141.0, 154.0, 162.5. Anal. Calcd
for C27H25BiS: C, 54.91; H, 4.27. Found: C, 54.99; H, 4.34.
Bis(4-chlorophenyl)(2-bromophenylthio)bismuthane (4c):
yellow solid; yield 40%; mp 101ꢀ102 °C; 1H NMR (400 MHz, CDCl3)
δ 6.98 (1H, dt, J = 1.6, 7.6 Hz), 7.11 (1H, dt, J = 1.6, 7.6 Hz), 7.47 (1H,
dd, J = 1.6, 7.6 Hz), 7.49 (4H, d, J = 8.4 Hz), 7.57 (1H, dd, J = 1.6,
7.6 Hz), 7.99 (4H, d, J = 8.4 Hz); 13C NMR (100 MHz, CDCl3) δ 127.4,
128.4, 130.9, 131.7, 133.0, 134.9, 136.3, 137.0, 138.8, 165.5. Anal. Calcd
for C18H12BiBrCl2S: C, 34.86; H, 1.95. Found: C, 34.82; H, 1.85.
Bis(4-methylphenyl)(2-methylphenylthio)bismuthane (6a).
yellow solid; yield 69%; mp 79ꢀ80 °C; 1H NMR (400 MHz, CDCl3)
δ 2.34 (6H, s), 2.42 (3H, s), 6.97ꢀ7.04 (2H, m), 7.14 (1H, dd, J = 1.2,
7.6 Hz), 7.35 (4H, d, J = 7.6 Hz), 7.35 (1H, dd, J = 1.2, 7.6 Hz), 7.95 (4H,
d, J = 7.6 Hz); 13C NMR (100 MHz, CDCl3) δ 21.6, 22.3, 126.0, 126.8,
130.0, 132.2, 135.2, 136.1, 137.3, 138.2, 141.6, 163.4. Anal. Calcd for
C21H21BiS: C, 49.03; H, 4.11. Found: C, 48.82; H, 4.10.
Reaction of Diaryl(arylthio)bismuthanes with Benzyne.
General Procedure. Method A: To a solution of diaryl(arylthio)-
bismuthane (0.3 mmol) in acetonitrile (3 mL) were added benzyne
precursor 2 (0.6 mmol) and CsF (1.5 mmol) at room temperature. The
reaction mixture was allowed to react at this temperature for 24 h. The
reaction was quenched with brine (5 mL), and the mixture was extracted
with ethyl acetate (5 mL ꢁ 3). The combined extracts were dried over
anhydrous sodium sulfate and evaporated to leave a residue, which was
chromatographed on silica gel with hexaneꢀethyl acetate (15:1) to give
the product. Method B: To a solution of diaryl(arylthio)bismuthane
(0.3 mmol) in THF (3 mL) were added benzyne precursor 2 (0.6 mmol),
KF (0.9 mmol), and 18-crown-6 (0.9 mmol) at 0 °C. The reaction
mixture was allowed to react at this temperature for 1 h and then at room
temperature for 11 h. The reaction was quenched with brine (5 mL), and
the mixture was extracted with ethyl acetate (5 mL ꢁ 3). The combined
extracts were dried over anhydrous sodium sulfate and evaporated to
leave a residue, which was chromatographed on silica gel with hexaneꢀ
ethyl acetate (15:1) to give the product.
Bis(4-methylphenyl)[2-(phenylthio)phenyl]bismuthane (3a):
colorless solid; yield 60%; mp 74ꢀ75 °C; 1H NMR (400 MHz, CDCl3)
δ 2.31 (6H, s), 7.08ꢀ7.11 (3H, m), 7.16 (2H, d, J = 7.4 Hz), 7.17 (4H, d,
J = 7.2 Hz) 7.24 (1H, dt, J = 1.2, 7.4 Hz), 7.31 (1H, dt, J = 1.2, 7.4 Hz),
7.57 (4H, d, J = 7.2 Hz), 7.57 (1H, dd, J = 1.2, 7.4 Hz), 7.80 (1H, dd, J =
1.2, 7.4 Hz); 13C NMR (100 MHz, CDCl3) δ 21.5, 125.9, 128.5, 128.9,
129.0, 131.1, 131.3, 135.2, 137.2, 137.6, 138.0, 139.0, 140.7, 154.1, 163.5.
Anal. Calcd for C26H23BiS: C, 54.17; H, 4.02. Found: C, 54.27; H, 4.05.
Diphenyl[2-(phenylthio)phenyl]bismuthane (3b): colorless
solid; yield 67%; mp 65ꢀ66 °C; 1H NMR (400 MHz, CDCl3) δ 7.09ꢀ
7.13 (3H, m), 7.19 (2H, t, J = 7.2 Hz), 7.28ꢀ7.40 (8H, m), 7.60 (1H, dd,
J = 1.2, 7.4 Hz), 7.69 (4H, d, J = 7.2 Hz), 7.79 (1H, dd, J = 1.2, 7.4 Hz);
13C NMR (100 MHz, CDCl3) δ 126.1, 127.6, 128.6, 129.0, 129.3, 130.5,
131.3, 135.4, 137.7, 137.9, 139.1, 140.8, 158.1, 164.1. Anal. Calcd for
C24H19BiS: C, 52.56; H, 3.49. Found: C, 52.45; H, 3.45.
Bis(4-chlorophenyl)[2-(phenylthio)phenyl]bismuthane (3c):
colorless solid, yield 65%; mp 60ꢀ61 °C; 1H NMR (400 MHz, CDCl3)
δ 7.06 (2H, d, J = 7.4 Hz), 7.12 (1H, t, J = 7.4 Hz), 7.18 (2H, t, J =
7.4 Hz), 7.32 (4H, d, J = 8.0 Hz), 7.33ꢀ7.40 (2H, m), 7.57 (4H, d, J =
8.0 Hz), 7.63 (1H, dd, J = 1.2, 7.4 Hz), 7.74 (1H, dd, J = 1.2, 7.4 Hz); 13C
NMR (100 MHz, CDCl3) δ 126.2, 128.3, 129.1, 129.6, 130.8, 131.6,
134.0, 135.8, 137.4, 138.7, 139.0, 140.4, 155.7, 164.1. Anal. Calcd for
C24H17BiCl2S: C, 46.69; H, 2.78. Found: C, 46.39; H, 2.77.
Bis(4-methylphenyl)[2-(4-methoxyphenylthio)phenyl]bis-
muthane (9a): colorless solid; yield 27% based on the starting 4-me-
1
thoxythiophenol (0.2 mmol); mp 103ꢀ104 °C; H NMR (400 MHz,
CDCl3) δ 2.34 (6H, s), 3.77 (3H, s), 6.77 (2H, d, J = 9.2 Hz), 7.16ꢀ7.20
(3H, m), 7.20 (4H, d, J = 8.0 Hz), 7.27 (1H, dt, J = 1.6, 7.6 Hz), 7.44 (1H,
dd, J = 1.6, 7.6 Hz), 7.60 (4H, d, J = 8.0 Hz), 7.74 (1H, dd, J = 1.6, 7.6 Hz);
13C NMR (100 MHz, CDCl3) δ 21.5, 55.3, 114.7, 127.5, 128.9, 130.1,
131.2, 131.3, 132.5, 133.1, 137.2, 137.5, 137.7, 138.7, 143.4, 158.9. Anal.
Calcd for C27H25BiOS: C, 53.47; H, 4.15. Found: C, 53.39; H, 4.21.
Synthesis of Arylbis(arylthio)bismuthanes. General Pro-
cedure. A typical example is exemplified by the synthesis of 12a. To a
solution of thiophenol (6 mmol) in methanol (5 mL) was added sodium
methoxide (7.2 mmol) at room temperature, and the resulting solution
was stirred for 30 min. To this solution thus obtained was added drop-
wise a suspension of dichloro(4-methyllphenyl)bismuthane (3 mmol),
prepared from tris(4-methylphenyl)bismuthane (1 mmol) and bismuth-
(III) chloride (2 mmol) in diethyl ether (10 mL) by stirring for 1 h at
room temperature, and the reaction mixture was stirred for 2 h at room
temperature. The reaction was quenched with brine (10 mL), and the
mixture was extracted with ethyl acetate (10 mL ꢁ 3). The combined
extracts were dried over anhydrous sodium sulfate and evaporated to
leave a residue, which was recrystallized from methanol to give 12a.
(4-Methylphenyl)bis(phenylthio)bismuthane (12a): yellow
solid; yield 47%; mp 158ꢀ159 °C (lit.18 155 °C); 1H NMR (400 MHz,
CDCl3) δ 2.35 (3H, s), 7.11 (2H, t, J = 7.2 Hz), 7.20 (4H, t, J = 7.2 Hz),
7.33 (4H, d, J = 7.2 Hz), 7.55 (2H, d, J = 7.2 Hz), 8.28 (2H, d, J = 7.2 Hz);
13C NMR (100 MHz, DMSO-d6) δ 21.5, 125.3, 128.2, 133.0, 134.3,
137.0, 138.0, 138.6, 190.9. Anal. Calcd for C19H17BiS2: C, 44.02; H, 3.31.
Found: C, 43.79; H, 3.33.
Bis(4-methylphenyl)[2-(2-bromophenylthio)phenyl]bis-
muthane (5a): colorless solid; yield 46%; mp 104ꢀ105 °C; 1H NMR
(400 MHz, CDCl3) δ 2.31 (6H, s), 6.59 (1H, dd, J = 1.6, 7.6 Hz), 6.92
(1H,dt,J=1.6,7.6Hz),6.96(1H,dt,J= 1.6, 7.6 Hz), 7.16 (4H, d, J=7.6Hz),
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Organometallics
ARTICLE
Bis(2-bromophenylthio)(4-methylphenyl)bismuthane (14a):
yellow solid; yield 46%; mp 186ꢀ187 °C; 1H NMR (400 MHz, CDCl3)
δ 2.35 (3H, s), 6.96 (1H, dt, J = 1.2, 7.2 Hz), 7.15 (1H, dt, J = 1.2, 7.2
Hz), 7.55ꢀ7.59 (6H, m), 8.47 (2H, d, J = 7.2 Hz); 13C NMR (100 MHz,
DMSO-d6) δ 21.6, 126.8, 127.3, 129.1, 132.4, 133.1, 136.0, 137.3, 138.9,
140.0, 191.9. Anal. Calcd for C19H15BiBr2S2: C, 33.75; H, 2.24. Found:
C, 33.57; H, 2.18.
(4-Methylphenyl)bis(2-methylphenylthio)bismuthane (16a):
yellow solid; yield 61%; mp 128ꢀ129 °C; 1H NMR (400 MHz, CDCl3)
δ 2.35 (3H, s), 2.46 (6H, s), 7.00ꢀ7.06 (4H, m), 7.17ꢀ7.20 (2H, m),
7.28ꢀ7.31 (2H, m), 7.55 (2H, d, J = 7.2 Hz), 8.32 (2H, d, J = 7.2 Hz);
13C NMR (100 MHz, DMSO-d6) δ 21.6, 22.2, 125.7 (ꢁ2), 129.5, 132.9,
135.3, 137.1, 137.3, 138.6, 140.9, 190.5. Anal. Calcd for C21H21BiS2: C,
46.15; H, 3.87. Found: C, 45.75; H, 3.82.
Reaction of Arylbis(arylthio)bismuthanes with Benzyne.
General Procedure. A typical example is exemplified by the reaction
of 12a. To a solution of 12a (0.3 mmol) in THF (3 mL) were added
benzyne precursor 2 (0.9 mmol), KF (1.8 mmol), and 18-crown-6
(1.8 mmol) at 0 °C under argon. The reaction mixture was allowed to
react at this temperature for 1 h and then at room temperature for 23 h.
The reaction was quenched with brine (5 mL), and the mixture was
extracted with ethyl acetate (5 mL ꢁ 3). The combined extracts were
dried over anhydrous sodium sulfate and evaporated to leave a residue,
which was chromatographed on silica gel with hexaneꢀethyl acetate
(15:1) to give 13a.
sodium methoxide (3.6 mmol) at room temperature, and the mixture
was stirred for 30 min. Chlorobis(4-methylphenyl)stibine (3 mmol) was
prepared by stirring tris(4-methylphenyl)stibine (2 mmol) and anti-
mony(III) chloride (1 mmol) for 5 h at 80 °C under neat conditions.
Then, the stibine thus obtained was diluted with diethyl ether (10 mL),
and the resulting solution was added dropwise to the solution of sodium
thiophenoxide at room temperature. After the reaction mixture was
stirred for 2 h at room temperature, the reaction was quenched with brine
(10 mL) and the mixture was extracted with ethyl acetate (10 mL ꢁ 3). The
combined extracts were dried over anhydrous sodium sulfate and eva-
porated to leave a residue, which was chromatographed on silica gel with
hexaneꢀethyl acetate (8:1) to give 18.
Bis(4-methylphenyl)(phenylthio)stibine (18): colorless solid;
yield 27%; mp 104ꢀ105 °C; 1H NMR (400 MHz, CDCl3) δ 2.36 (6H,
s), 7.16ꢀ7.19 (3H, m), 7.21 (4H, d, J = 7.6 Hz), 7.41ꢀ7.43 (2H, m),
7.54 (4H, d, J = 7.6 Hz); 13C NMR (100 MHz, CDCl3) δ 21.4,
126.4, 128.8, 129.9, 133.7, 135.0, 135.3, 136.9, 139.2. Anal. Calcd for
C20H19SSb: C, 58.14; H, 4.63. Found: C, 57.97; H, 4.50.
Reaction of 18 with Benzyne. To a solution of 18 (0.3 mmol) in
THF (3 mL) were added benzyne precursor 2 (0.6 mmol), KF (0.9 mmol),
and 18-crown-6 (0.9 mmol) at 0 °C under argon. The reaction mixture
was stirred at this temperature for 1 h and then at room temperature for
17 h. The reaction was quenched with brine (5 mL), and the mixture was
extracted with ethyl acetate (5 mL ꢁ 3). The combined extracts were
dried over anhydrous sodium sulfate and evaporated to leave a residue,
which was chromatographed on silica gel with hexaneꢀethyl acetate
(15:1) to give 19.
Bis(4-methylphenyl)[2-(phenylthio)phenyl]stibine (19):
colorless solid; yield 58%; mp 95ꢀ96 °C; 1H NMR (400 MHz, CDCl3)
δ 2.34 (6H, s), 7.10ꢀ7.14 (7H, m), 7.17ꢀ7.20 (4H, m), 7.28 (4H, d,
J = 7.6 Hz), 7.27ꢀ7.32 (1H, m), 7.47 (1H, d, J = 7.6 Hz); 13C NMR
(100 MHz, CDCl3) δ 21.4, 126.1, 128.8, 128.9 (ꢁ2), 129.7, 129.8,
134.5, 135.5, 136.3, 136.6, 137.5, 138.2, 141.2, 146.8. Anal. Calcd for
C26H23SSb: C, 63.82; H, 4.74. Found: C, 63.93; H, 4.86.
Synthesis of 20. To a solution of thiophenol (0.31 mL, 3 mmol) in
methanol (3 mL) was added sodium methoxide (194 mg, 3.6 mmol) at
room temperature, and the mixture was stirred for 30 min. To this
solution thus obtained was added dropwise a suspension of diphenyl-
chlorarsine13c (3 mmol), prepared from phenylmagnesium chloride (6
mmol) and arsenic(III) chloride (3 mmol) in THF (10 mL) by stirring
for 2 h at 0 °C, and the reaction mixture was stirred for 3 h at room
temperature. The reaction was quenched with brine (10 mL), and the
mixture was extracted with ethyl acetate (10 mL ꢁ 3). The combined
extracts were dried over anhydrous sodium sulfate and evaporated to
leave a residue, which was chromatographed on silica gel with hexaneꢀ
ethyl acetate (10:1) to give the product.
Diphenyl(phenylthio)arsine (20): colorless solid; yield 49%;
mp 39ꢀ40 °C (lit.13b 40ꢀ42 °C); 1H NMR (400 MHz, CDCl3) δ 7.23
(1H, t, J = 7.4 Hz), 7.28ꢀ7.36 (12H, m), 7.51 (2H, d, J = 7.4 Hz); 13C
NMR (100 MHz, CDCl3) δ 127.1, 127.5, 128.4, 128.6, 129.0, 133.7,
137.0, 139.6.
Bis[2-(phenylthio)phenyl](4-methylphenyl)bismuthane
1
(13a): colorless solid; yield 30%; mp 116ꢀ117 °C; H NMR (400
MHz, CDCl3) δ 2.32 (3H, s), 7.06ꢀ7.10 (6H, m), 7.13ꢀ7.18 (6H, m),
7.26 (2H, dt, J = 1.2, 7.4 Hz), 7.34 (2H, dt, J = 1.2, 7.4 Hz), 7.53 (2H, d,
J = 7.6 Hz), 7.58 (2H, dd, J = 1.2, 7.4 Hz), 7.75 (2H, dd, J = 1.2, 7.4 Hz);
13C NMR (100 MHz, CDCl3) δ 21.6, 125.9, 128.4, 128.9, 129.1, 131.3,
131.5, 135.5, 137.1, 137.7, 137.9, 139.2, 140.5, 157.2, 166.8. Anal. Calcd
for C31H25BiS2: C, 55.52; H, 3.76. Found: C, 55.80; H, 4.04.
Bis[2-(4-chlorophenylthio)phenyl](4-methylphenyl)bis-
1
muthane (11a): colorless solid; yield 31%; mp 126ꢀ127 °C; H
NMR (400 MHz, CDCl3) δ 2.33 (3H, s), 6.94 (4H, d, J = 8.4 Hz), 7.08
(4H, d, J = 8.4 Hz), 7.17 (2H, d, J = 7.2 Hz), 7.29 (2H, dt, J = 1.2, 7.4 Hz),
7.36 (2H, dt, J = 1.2, 7.4 Hz), 7.48 (2H, d, J = 7.2 Hz), 7.60 (2H, dd, J =
1.2, 7.4 Hz), 7.74 (2H, dd, J = 1.2, 7.4 Hz); 13C NMR (100 MHz,
CDCl3) δ 21.5, 129.0, 129.3, 129.4, 131.5, 131.7, 131.8, 135.8, 136.5,
137.4, 137.6, 139.3, 140.0, 157.0, 166.8. Anal. Calcd for C31H23BiCl2S2:
C, 50.35; H, 3.13. Found: C, 50.34; H, 3.25.
Bis[2-(2-bromophenylthio)phenyl](4-methylphenyl)bis-
1
muthane (15a): colorless solid; yield 32%; mp 140ꢀ141 °C; H
NMR (400 MHz, CDCl3) δ 2.30 (3H, s), 6.62 (2H, dd, J = 1.2, 7.6 Hz),
6.90 (2H, dt, J = 1.2, 7.6 Hz), 6.96 (2H, dt, J = 1.2, 7.6 Hz), 7.15 (2H, d,
J = 7.6 Hz), 7.33 (2H, dt, J = 1.2, 7.4 Hz), 7.39 (2H, dt, J = 1.2, 7.4 Hz),
7.45 (2H, dd, J = 1.2, 7.6 Hz), 7.50 (2H, d, J = 7.6 Hz), 7.61 (2H, dd, J =
1.2, 7.4 Hz), 7.81 (2H, dd, J = 1.2, 7.4 Hz); 13C NMR (100 MHz,
CDCl3) δ 21.5, 121.2, 126.5, 127.7, 128.2, 129.4, 131.5, 132.1, 132.7,
136.6, 137.1, 137.6, 139.0, 139.5, 139.7, 157.8, 168.2. Anal. Calcd for
C31H23BiBr2S2: C, 44.95; H, 2.80. Found: C, 45.17; H, 2.96.
Synthesis of 24. To a solution of thiophenol (6 mmol) in methanol
(5 mL) was added sodium methoxide (7.2 mmol) at room temperature,
and the mixture was stirred for 30 min. Dichloro(4-methylphenyl)sti-
bine (3 mmol) was prepared by stirring tris(4-methylphenyl)stibine
(1 mmol) and antimony(III) chloride (2 mmol) for 5 h at 80 °C under
neat conditions. Then, the stibine thus obtained was diluted with diethyl
ether (10 mL), and the resulting solution was added dropwise to the
solution of sodium thiophenoxide. After the reaction mixture was stirred
for 2 h at room temperature, the reaction was quenched with brine
(10 mL) and the mixture was extracted with ethyl acetate (10 mL ꢁ 3).
The combined extracts were dried over anhydrous sodium sulfate and
evaporated to leave a residue, which was recrystallized from methanol
to give 24.
Bis[2-(2-methylphenylthio)phenyl](4-methylphenyl)bis-
1
muthane (17a): colorless solid; yield 52%; mp 114ꢀ115 °C; H
NMR (400 MHz, CDCl3) δ 2.28 (6H, s), 2.32 (3H, s), 6.87 (2H, dd, J =
1.2, 7.6 Hz), 6.94 (2H, dt, J = 1.2, 7.6 Hz), 7.03 (2H, dt, J = 1.2, 7.6 Hz),
7.12 (2H, d, J = 7.6 Hz), 7.18 (2H, d, J = 7.6 Hz), 7.24 (2H, dt, J = 1.2, 7.4
Hz), 7.31 (2H, dt, J = 1.2, 7.4 Hz), 7.43 (2H, dd, J = 1.2, 7.4 Hz), 7.53
(2H, d, J = 7.6 Hz), 7.76 (2H, dd, J = 1.2, 7.4 Hz); 13C NMR (100 MHz,
CDCl3) δ 20.5, 21.5, 126.2, 126.5, 129.1, 129.2, 130.2, 130.8, 131.5,
134.5, 136.5, 136.7, 136.8, 137.1, 137.7, 139.3, 140.9, 157.0, 165.6. Anal.
Calcd for C33H29BiS2: C, 56.73; H, 4.18. Found: C, 56.51; H, 4.27.
Synthesis of Bis(4-methylphenyl)(phenylthio)stibine (18).
To a solution of thiophenol (3 mmol) in methanol (3 mL) was added
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dx.doi.org/10.1021/om200228x |Organometallics 2011, 30, 4532–4538

Organometallics
ARTICLE
(4-Methylphenyl)bis(phenylthio)stibine (24): colorless solid;
’ REFERENCES
1
yield 53%; mp 110ꢀ111 °C; H NMR (400 MHz, CDCl3) δ 2.38
(1) (a) Kitamura, T.; Yamane, M.; Inoue, K.; Todaka, M.; Fukatsu,
N.; Meng, Z.; Fujiwara, Y. J. Am. Chem. Soc. 1999, 121, 11674. (b)
Pellissier, H.; Santelli, M. Tetrahedron 2003, 59, 701. (c) Pintori, D. G.;
Greaney, M. F. Org. Lett. 2010, 12, 168. (d) Dubrovskiy, A. V.; Larock,
R. C. Org. Lett. 2010, 12, 3117.
(3H, s), 7.18ꢀ7.21 (6H, m), 7.26 (2H, d, J = 7.6 Hz), 7.39ꢀ7.42
(4H, m), 7.65 (2H, d, J = 7.6 Hz); 13C NMR (100 MHz, CDCl3) δ 21.5,
127.1, 128.9, 130.1, 133.3, 134.5, 134.7, 138.5, 140.1. Anal. Calcd for
C19H17S2Sb: C, 52.92; H, 3.97. Found: C, 53.01; H, 3.99.
(2) (a) Yoshida, H.; Honda, Y.; Shirakawa, E.; Hiyama, T. Chem.
Commun. 2001, 1880. (b) Yoshida, H.; Terayama, T.; Ohshita, J.; Kunai,
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Reaction of 24 with Benzyne. To a solution of 24 (0.3 mmol) in
THF (3 mL) were added benzyne precursor 2(0.9 mmol), KF (1.8 mmol),
and 18-crown-6 (1.8 mmol) at 0 °C under argon. The reaction mixture
was allowed to react at this temperature for 1 h and then at room
temperature for 29 h. The reaction was quenched with brine (5 mL), and
the mixture was extracted with ethyl acetate (5 mL ꢁ 3). The combined
extracts were dried over anhydrous sodium sulfate and evaporated to
leave a residue, which was chromatographed on silica gel with hexaneꢀ
ethyl acetate (15:1) to give 25.
(4-Methylphenyl)bis[2-(phenylthio)phenyl]stibine (25):
1
colorless solid; yield 51%; mp 104ꢀ105 °C; H NMR (400 MHz,
CDCl3) δ 2.33 (3H, s), 7.07ꢀ7.11 (8H, m), 7.14ꢀ7.16 (6H, m), 7.19
(2H, dt, J = 1.2, 7.4 Hz), 7.24 (2H, d, J = 7.6 Hz), 7.30 (2H, dt, J = 1.2, 7.4
Hz), 7.48 (2H, dd, J = 1.2, 7.4 Hz); 13C NMR (100 MHz, CDCl3) δ
21.4, 126.1, 128.8, 128.9 (ꢁ2), 129.7, 129.8, 134.6, 136.3, 136.5, 136.8,
137.5, 138.1, 141.1, 148.1. Anal. Calcd for C31H25S2Sb: C, 63.82; H,
4.32. Found: C, 63.86; H, 4.37.
Coupling Reaction. To a solution of 5a (0.1 mmol) or 15a (0.1
mmol) in DMSO (2 mL) were added Pd(dppf)Cl2 (3 mol %) and CsF
(0.75 mmol) at 120 °C under argon. The mixture was stirred for 20 h (in
the case of 5a) or 10 h (in the case of 15a) at this temperature. The
reaction was quenched with water (5 mL) after being cooled to room
temperature, and then the mixture was extracted with ethyl acetate
(5 mL ꢁ 3). The combined extracts were dried over anhydrous sodium
sulfate and evaporated to leave a residue, which was chromatographed
on silica gel with hexaneꢀethyl acetate (15:1) to give dibenzothiophene.
Dibenzothiophene: colorless solid; yield 81% from 5a and 54%
from 15a; mp 99ꢀ100 °C (lit.16b 100ꢀ102 °C); 1H NMR (400 MHz,
CDCl3) δ 7.44ꢀ7.49 (4H, m), 7.84ꢀ7.89 (2H, m), 8.15ꢀ8.19 (2H, m).
X-ray Crystallography. All measurements were made with a
Rigaku Mercury CCD area detector with graphite-monochromated Mo
KR radiation. The data were collected at a temperature of ꢀ100 ( 1 °C
to a maximum 2θ value of 55.0°. The structure was solved by direct me-
thods and expanded using Fourier techniques. The non-hydrogen atoms
were refined anisotropically. All hydrogen atoms were placed in calcu-
lated positions and not refined. All calculations were performed using
the CrystalStructure crystallographic software package. Details of crystal
data, data collection summary, and refinement parameters of compound
5a are given in the Supporting Information.
(5) Organobismuth Chemistry; Suzuki, H., Matano, Y., Eds.; Elsevier:
Amsterdam, 2001.
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’ ASSOCIATED CONTENT
S
Supporting Information. Crystal data for compound 5a
b
and copies of 1H and 13C NMR spectra for all new compounds.
This material is available free of charge via the Internet at http://
pubs.acs.org.
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’ ACKNOWLEDGMENT
Support from the Japan Society for the Promotion of Science
(Grant-in-Aid for Scientific Research, No. 22550039) is grate-
fully acknowledged. We are grateful to the Center of Instru-
mental Analysis, Yamaguchi University, and the Elemental
Analytical Center affiliated with the Faculty of Science, Kyushu
University.
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dx.doi.org/10.1021/om200228x |Organometallics 2011, 30, 4532–4538