Extension of the Heck reaction to the arylation of activated thiophenes

Article abstract of DOI:10.1016/S0022-328X(98)00667-6

The direct arylation of activated thiophenes was accomplished in moderate to good yields using a Heck-type reaction with the mixture of Pd(OAc)₂ and n-Bu₄NBr as a catalytic system. This new arylation method is applied to different derivatives and has proved to be compatible with sensitive functional groups. Furthermore, the substituent nature and position on the thiophene moiety influence the cross coupling. In particular the substitution is regiospecific when the heterocycle is substituted at position 2 with an electron withdrawing group.

Full text of DOI:10.1016/S0022-328X(98)00667-6

Journal of Organometallic Chemistry 567 (1998) 49–55
Extension of the Heck reaction to the arylation of activated
thiophenes
L. Lavenot, C. Gozzi, K. Ilg, I. Orlova, V. Penalva, M. Lemaire *
Institut de Recherches sur la Catalyse et Laboratoire de Catalyse et Synthe`se Organique, CNRS, Uni6ersite´ C. Bernard CPE, Baˆt. 308,
43 bd. du 11 no6, 69622 Villeurbanne, France
Received 6 October 1997; received in revised form 25 November 1997
Abstract
The direct arylation of activated thiophenes was accomplished in moderate to good yields using a Heck-type reaction with the
mixture of Pd(OAc)2 and n-Bu4NBr as a catalytic system. This new arylation method is applied to different derivatives and has
proved to be compatible with sensitive functional groups. Furthermore, the substituent nature and position on the thiophene
moiety influence the cross coupling. In particular the substitution is regiospecific when the heterocycle is substituted at position
2 with an electron withdrawing group. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Heck reaction; Activated thiophenes; Arylation
1. Introduction
reaction of a heteroaryltrialkylstannanes with an aryl
halide catalysed by a palladium complex. Although
they are all efficient cross-coupling methods, these three
methods have several drawbacks. First of all, they are
poorly compatible with a number of important func-
tional groups. In addition, these methods require a
specific activation of both substrate and reagent, and
this increases the overall number of steps in a desired
synthesis [6].
Recently, we have reported that activated thiophenes
can be successfully arylated by the Heck method [7]
using Jeffery conditions [8]. In this paper, the full
results about our investigations for this new application
of the Heck reaction are described. Our first objective is
to underline the various conditions which can affect the
selectivity and kinetics of the reactions. These investiga-
tions were carried out with a particular example, the
reaction of thiophene-3-carboxaldehyde with iodoben-
zene. In the second part of this article, the reaction is
applied to different derivatives bearing various activat-
ing groups such as aldehyde, cyano, nitro, methoxy,
trifluoromethane, in order to evaluate scope and limita-
tions of this new method.
The introduction of functionalized aryl moieties onto
heterocyclic compounds is an important task in organic
synthesis. We are particularly interested in the prepara-
tion of functionalized thiophenes in order to obtain
monomers suitable for the synthesis of regioregular
polymers with high electrical conductivity [1,2]. As the
chemistry of thiophene oligomers offers wide applica-
tions in the field of electrically conducting polymers, the
search for a new and easier way to prepare them
remains a topical issue. Methods to get unsymmetrical
aryl–aryl coupling have been developed by Suzuki [3],
Kumada [4] and Stille [5]. The Suzuki reaction consists
of the cross coupling of an arylboronic acid with an
aryl halide catalysed by a palladium phosphine complex
in the presence of sodium carbonate. Kumada and
co-workers described an efficient method based on a
nickel-catalysed coupling between a Grignard reagent
and an organo halide. The Stille method implies the
* Corresponding author. Tel.: +33 4 72431408; fax: +33 4
72431408; e-mail: Marc.Lemaire@univ-lyon1.fr
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00667-6

50
L. La6enot et al. / Journal of Organometallic Chemistry 567 (1998) 49–55
Scheme 1. Arylation of thiophene-3-carboxaldehyde with iodobenzene.
Table 1
Arylation of thiophene-3-carboxaldehyde with iodobenzene catalysed by the mixture Pd(OAc)2/PPh3/n-Bu4NBr (0.05/0.1/1)
Entry
1 (mol l−1
)
2 (mol l−1
)
Solvent
Time (h)
Conversionb (%)
Selectivityb (%)
3a/5a/6a
1
2
3
4
5
6
1
2
8
4
4
4
1
1
4
1
1
1
CH3CN/H2O
CH3CN/H2O
CH3CN/H2O
CH3CN/H2O
H2O
10.5
9
4
2.5
5
48
59
51/4/45
57/9/34
57/15/28
66/6/28
56/4/40
61/4/40
100
100
100
100
93
CH3CNa
a Base=AcONa.
b Determined by GC analysis on an apolar column.
2. Study of reaction conditions with
thiophene-3-carboxaldehyde
tions and thiophene-3-carboxaldehyde/iodobenzene
ratio on the selectivity and reaction rate has been
evaluated. The use of equimolar ratio of thiophene-3-
carboxaldehyde and iodobenzene (Table 1, entry 1)
leads to a low reaction rate and a moderate selectivity.
When the usual ratio for Heck reaction (1a/2a: 2/1,
Table 1, entry 2) is used, the rate is increased but the
selectivity remains modest. Nevertheless, a large excess
of 1a (1a/2a: 4/1, Table 1, entry 4) provides the most
selective and the fastest reaction. However, a large
Under the classical conditions of Heck, the reaction
gives rise to only traces of product. But under the
conditions described by Jeffery [9], the coupling of
thiophene-3-carboxaldehyde 1a with iodobenzene 2a
leads selectively to 2-phenylthiophene-3-carboxaldehyde
3a. The formation of the isomer 4a resulting from a
minor activation of position 4 and consequently the
formation of a 2,4-disubstituted product 5a are also
observed. But, only small amounts of 4a and 5a are
formed and has been identified by GC/MS coupling.
Finally, biphenyl 6a resulting from an Ullmann type
coupling type competitive reaction is produced (Scheme
1).
In order to favour thiophene arylation, several condi-
tions have been systematically studied and the influence
of various parameters on the kinetics, selectivity and
yield has been determined. The parameters studied are:
thiophene/iodobenzene ratio and concentrations, sol-
vent conditions and catalytic systems based on Pd(II)
precursors, Pd(OAc)2 and PdCl2. Palladium acetate is
used with tetra-n-butylammonium bromide with or
without phosphine. Palladium chloride is used in asso-
ciation with LiCl salt as described by Miura et al.[10].
Results obtained with the mixture Pd(OAc)2/
n-Bu4NBr/PPh3, as a catalytic system are compiled in
Table 1.
increase of concentrations (thiophene
8 M and
iodobenzene 4 M) allows the use of a limited thiophene
excess (1a/2a: 2/1) preserving good rate and selectivity.
The reaction appears to be largely influenced by con-
centration (Table 1, entry 3), but the required amount
of potassium carbonate (2.5 equivalents) limits this
possibility.
Various solvent conditions, anhydrous or aqueous
ones, have also been tested with the catalytic system
Pd(OAc)2/PPh3/n-Bu4NBr. In the absence of water
(Table 1, entry 6), the selectivity is similar to that
obtained with the mixture CH3CN/H2O (9/1) (Table 1,
entry 4) but the rate is drastically slowed down (48 h to
reach 93% conversion). In water (Table 1, entry 5),
total conversion is achieved after 5 h as in the mixture
CH3CN/H2O (9/1), but a loss of selectivity is observed.
Under these conditions, the competing formation of
biphenyl is favoured. Actually, the best solvent is a
CH3CN/H2O (9/1) mixture that allows both efficient
reaction and good selectivity.
Following conditions described by Jeffery, with a
mixture of Pd(OAc)2/PPh3/n-Bu4NBr in aqueous ace-
tonitrile as catalytic system, the influence of concentra-
Recently, Miura et al. [10] described the reaction of
salicylaldehydes with aryl iodides catalysed by a PdCl2/

L. La6enot et al. / Journal of Organometallic Chemistry 567 (1998) 49–55
51
Table 2
Arylation of thiophene-3-carboxaldehyde with iodobenzene catalysed by a mixture PdCl2/LiCl (0.05/0.2)
Entry
1 (mol l−1
)
2 (mol l−1
)
Solvent
Time (h)
Conversiona (%)
Selectivitya (%)
3a/5a/6a
1
2
3
4
4
4
1
1
1
CH3CN/H2O
DMF/H2O
DMF
25
28
22
96
100
59
78/4/18
50/2/48
54/3/43
a Determined by GC analysis on an apolar column.
LiCl mixture. In order to evaluate the influence of the
nature of the palladium precursor, we tested PdCl2
replacing the Pd(OAc)2/PPh3/n-Bu4NBr mixture with
the PdCl2/LiCl system (Table 2).
PdCl2 in combination with LiCl provides a catalyst
which is slightly more selective (Table 2, entry 1) than
Pd(OAc)2/PPh3/n-Bu4NBr (Table 1, entry 4), but the
reaction rate appears to be much slower (25 h instead
of 2.5 h with catalyst A). This rate decrease is observed
whatever the solvent used, but the CH3CN/H2O (9/1)
mixture leads to the best selectivity.
pling is regioselective at position 2, traces of a regioiso-
mer resulting from a minor activation are always
observed. However, these two regioisomers could not
be isolated. Actually, we attribute the minor activation
at position 4 in comparison with the disubstitution
product also formed and which could be isolated in the
case of 5b and 5c. Indeed, the 13C-NMR analysis of
disubstitution product 5b indicates that the arylation of
thiophene occurs at positions 2 and 4. So, the substitu-
tion appears to be related to the activation by the cyano
group predominantly and the sulfur effect appears to be
minor.
The reaction between 3-cyanothiophene and iodo-
naphthalene (entry 2) leads to a drastic loss of selectiv-
ity and 2,4-dinaphthyl-3-cyanothiophene 5c is formed
in up to 47% yield. In this case, the selectivity seems to
be related to steric hindrance of the iodoaryl moiety, so
the activation at position 4 is not yet negligible.
On the other hand, 2-substituted thiophenes 7 are
subject to a regiospecific arylation at the 5-position, a
single regioisomer 8 is obtained, no traces of substitu-
tion at the 3-position are observed. The competitive
formation of biaryl 6 depends on the nature of the
activating group Z (Scheme 2, Table 5).
In spite of regiospecificity, thiophene-2-carboxalde-
hyde 7a (Table 5, entry 1) is less reactive than thio-
phene-3-carboxaldehyde 1a (Table 4, entry 1). This lack
of reactivity leads to the formation of biaryl 6 as the
major product. Furthermore, 2-nitrothiophene (entry 2)
gives lower yields due to lack of stability of the sub-
strate and its derivatives which are very light sensitive.
Therefore, 2-nitrothiophene has to be purified before
use and the reaction has to be performed in darkness.
However, an isomerisation of 2-nitrothiophene can oc-
cur and lead to a loss of regiospecificity. Actually,
traces of a regioisomer are detected and the formation
of two monosubstituted isomers is confirmed by GC/
MS coupling. A 2,4-diarylated product 5d has been
The comparison of Tables 1 and 3 underlines the
influence of the phosphine ligand.
The mixture Pd(OAc)2/n-Bu4NBr (0.05/1) exhibits a
similar behaviour with or without phosphine addition.
The use of Pd(OAc)2/n-Bu4NBr without added phos-
phine ligand as a catalytic system (Table 3, entry 1)
slightly decreases the reaction rate but leads to a better
selectivity than the usual catalyst Pd(OAc)2/PPh3/
n-Bu4NBr (Table 1, entry 4). The comparison of Tables
2 and 3 reveals that the Pd(OAc)2/n-Bu4NBr (0.05/1)
catalyst is as selective as the PdCl2/LiCl catalytic system
with a rate comparable to that with Pd(OAc)2/PPh3/n-
Bu4NBr.
3. Scope and limitations
Attempts to achieve a Heck coupling of benzalde-
hyde or benzonitrile were unsuccessful. The arylation of
substituted thiophenes has shown that the nature and
position of the substituent influence the cross-coupling.
Reactions of thiophene-3-carboxaldehyde or 3-cyano-
thiophene, is regioselective at position 2 (Scheme 3 and
Table 4).
A cyano moiety also activates thiophene for the
coupling reaction (entries 1 and 2). Although the cou-

52
L. La6enot et al. / Journal of Organometallic Chemistry 567 (1998) 49–55
Table 3
Arylation of thiophene-3-carboxaldehyde with iodobenzene catalysed by Pd(OAc)2/n-Bu4NBr (0.05/1) without a phosphine ligand
Entry
1 (mol l−1
)
2 (mol l−1
)
Solvent
Time (h)
Conversiona (%)
Selectivitya (%)
3a/5a/6a
1
2
3
4
5
4
8
2
4
4
1
4
1
4
1
CH3CN/H2O
CH3CN/H2O
CH3CN/H2O
CH3CN/H2O
H2O
5
3.5
8
4
6
100
100
100
98
74/8/16
70/15/15
69/4/27
52/24/24
61/4/35
97
a Determined by GC analysis on an apolar column.
On the other hand, 2-activated thiophenes are subject
to a regiospecific reaction at position 5. Indeed, this
position is favored by both the sulfur and the activating
group effect (with conjugation). Bromoaryls may be
used instead of iodoaryls. Thus, the reaction of 2-cyan-
othiophene 7b with bromobenzene 2g yields 5-phenyl-2-
cyanothiophene (Scheme 3).
isolated and characterized by NMR spectroscopy. Both
by-products could arise after the isomerization of 2-ni-
trothiophene into 3-nitrothiophene.
Although bromoaryls are less reactives than iodo
ones, their use offers a larger range for synthetic appli-
cations. On the other hand, the chlorobenzene did not
react with 2-cyanothiophene.
Nevertheless, the arylation of 2-cyanothiophene
(Table 5, entries 3–7) proceeds regiospecifically with
good isolated yields and limited formation of biaryl 6.
It is noteworthy that the substitution rate and kinetic
data are not really sensitive to electronic effects on the
aryl iodide and to steric hindrance. Indeed, yields and
reaction times are similar with electron donating as well
as withdrawing substituents on the iodoaryl moiety
(Table 5, entries 3–5) and with more or less sterically
crowded substrates (Table 5, entries 6–7). On the con-
trary, sterically demanding iodoaryl reagents appear to
yield less of the Ullmann type product 6 and more of
the selectively Heck type product 8.
4. Conclusion
In this paper, we have shown that a one step aryla-
tion of thiophene derivatives can be performed with
Pd(OAc)2/n-Bu4NBr as catalytic system. The reaction
proceeds with moderate yields with thiophene-2-car-
boxaldehyde and best results were obtained with 2-
cyanothiophene because of a fast and regiospecific
substitution. Compared to usual reactions, the large
chemocompatibility of our method allows the synthesis
of biaryls bearing various functional groups such as
sensitive carboxaldehyde, cyano or nitro. So, this new
reaction seems to be powerful for the synthesis of
unsymmetrical and functionalized biaryls which are
Thiophenes 1 bearing an electron withdrawing group
react regioselectively at position 2 due to the balance
between the sulfur and substituent effect. Substitution
at position 4 can also occur but less than at position 2.
Table 4
Arylation of 3-substituted thiophenes with various aryl iodides
a
Determined on an apolar column.

L. La6enot et al. / Journal of Organometallic Chemistry 567 (1998) 49–55
53
Scheme 2. Arylation of thiophenes activated at position 2.
useful intermediates for the preparation of condensed
ring systems. Research about the real nature of the
catalyst to extend this reaction to other heterocycles is
currently underway.
apolar type column (JW DB-5, 95% dimethyl-(5%)-
diphenylpolysiloxane, L=15 m, ¥=0.25 mm), GC-
mass spectra were obtained on a FISONS MD 800
spectrometer. NMR spectra were recorded on
BRUKER AC 200 spectrometer.
a
5. Experimental part
5.2. General procedure for the reacti6ity studies
5.1. Apparatus
A suspension of potassium carbonate (2.5 equiva-
lents) and various catalytic systems in an acetonitrile/
GC and GC-mass analysis were carried out on an
Table 5
Arylation of thiophenes activated at position 2
a
Determined on an apolar column.

54
L. La6enot et al. / Journal of Organometallic Chemistry 567 (1998) 49–55
Scheme 3. Phenylation of 2-cyanothiophene with bromobenzene.
1
water mixture (9/1) was stirred under nitrogen for 5 min.
As a catalytic system either a mixture of tetra-n-butylam-
monium bromide (one equivalent) and triphenylphos-
phine (0.1 equivalent) and palladium acetate (0.05
equivalent) (Table 1) or a mixture of lithium chloride (0.2
equivalent) and palladium chloride (0.05 equivalent)
(Table 2) or a mixture of tetra-n-butylammonium bro-
mide (one equivalent) and palladium acetate (0.05 equiv-
alent) (Tables 3–5) were used. Substituted thiophene and
iodoaryl were successively added. The mixture was
heated at 80°C for the time indicated. After cooling to
room temperature, water and ether were added. The
organic phase was washed with water and dried over
MgSO4. After removal of the solvent under vacuum, the
substitution product was purified by column chromatog-
raphy.
3c. Isolated yield: 27%; H-NMR (200 MHz, CDCl3)
l 7.39 (1H, d, J=5.3 Hz); 7.50 (1H, d, J=5.3 Hz);
7.52–7.62 (4Hnaphtyl, M); 7.85–8.00 (3Hnaphtyl, M);
13C-NMR (50 MHz, CDCl3) l 110.5 (C); 115.0 (CN);
125.1 (CHnaphtyl); 125.2 (CHnaphtyl); 126.6
(CHnaphtyl); 126.9 (CHnaphtyl); 127.2 (CH); 128.3
(Cnaphtyl); 128.6 (CHnaphtyl); 129.2 (CHnaphtyl);
129.3 (CHnaphtyl); 130.5 (CH); 131.7 (Cnaphtyl); 133.8
(Cnaphtyl); 152.2 (C).
5.5. Characterization of 2,3,4-trisubstituted thiophenes
5
5b. Isolated yield: 5%, yellow solid; m.p.=137.5°C,
1H-NMR (200 MHz, CDCl3) l 3.84 (3H, s); 3.86 (3H,
s); 6.94 (2H, d, J=9.2 Hz); 6.99 (2H, d, J=9.2 Hz); 7.27
(1H, s); 7.50 (2H, d, J=8.7 Hz); 7.73 (2H, d, J=8.7 Hz);
13C-NMR (50 MHz, CDCl3) l 55.5 (2×CH3); 105.5 (C);
114.7 (4×CHarom); 116.3 (CN); 124.2 (2×Carom);
125.3 (CH); 127.3 (2×CHarom); 128.9 (2×CHarom);
143.2 (C); 151.8 (C); 160.2 (Carom); 160.8 (Carom);
HRMS calc. for C19H15NO2S (M+): 321.0823507,
found: 321.0830000.
5c. Isolated yield: 12%, yellow solid; m.p.=85°C,
1H-NMR (200 MHz, CDCl3) l 7.49 (1H, s), 7.53–7.63
(8Hnaphtyl, M); 7.92–8.01 (6Hnaphtyl, M); 13C-NMR
(50 MHz, CDCl3) l 11.4 (C); 115.2 (CN); 125.1
(CHnaphtyl);125.2 (CHnaphtyl); 125.3 (CHnaphtyl);
125.4 (CHnaphtyl); 126.5 (CHnaphtyl); 126.6
(CHnaphtyl); 127.2 (CHnaphtyl); 127.3 (CHnaphtyl);
128.4 (Cnaphtyl); 128.6 (2×CHnaphtyl); 128.7 (2×
CHnaphtyl); 129.3 (CHnaphtyl); 129.7 (CHnaphtyl);
130.1 (Cnaphtyl); 130.6 (CH); 131.5 (Cnaphtyl); 131.6
(Cnaphtyl); 133.9 (Cnaphtyl); 134.0 (Cnaphtyl); 143.5
(C); 152.0 (C); HRMS calc. for C25H15NS (M+):
361.0925214, found: 361.0934000.
5.3. Typical procedure for study of the scope and
limitations
A suspension of potassium carbonate (40 mmol)
tetra-n-butylammonium bromide (16 mmol) and palla-
dium acetate (0.8 mmol) in an acetonitrile/water mixture
(3.7/0.4 ml) was stirred under nitrogen for 5 min.
Substituted thiophene 1 or 7 (32 mmol) and iodoaryl 2
(16 mmol) were successively added. The mixture was
heated at 80°C for the time indicated. After cooling to
room temperature, water and ether were added. The
organic phase was washed with water and dried over
MgSO4. After removal of the solvent under vacuum, the
substitution product was purified by column chromatog-
raphy or recrystallization.
5.4. Characterization of 2,3-disubstituted thiophenes 3
1
3a. Isolated yield: 35%; colorless oil; H-NMR (200
MHz, CDCl3) l 7.26 (1H, d, J=5.4 Hz), 7.48 (5H, m),
7.56 (1H, d, J=5.4 Hz), 9.87 (1H, s); 13C-NMR (50
MHz, CDCl3) l 125.1 (CH), 126.6 (CH), 128.9
(CHarom), 129.4 (Carom), 130.1 (CHarom), 131.4
(Carom), 137.1 (C), 156.1 (C), 185.8 (CHO); HRMS calc.
for C11H8OS (M+): 188.0295868, found: 188.0293000.
Compound 3a is known see Ref. [11].
3b. Isolated yield: 30%; white solid; m.p.=45.5°C;
13C-NMR (50 MHz, CDCl3) l 55.5 (CH3), 105.1 (C),
114.7 (CHarom), 116.2 (CN), 123.9 (Carom), 124.5
(CH), 129.2 (CHarom), 130.2 (CH), 154.1 (C), 160.9
(Carom); HRMS calc. for C12H9NOS (M+):
215.0404858, found: 215.0412000.
5d. Isolated yield: 4%, orange solid; m.p.=136°C;
1H-NMR (200 MHz, CDCl3) l 3.85 (3H, s), 3.87 (3H,
s), 6.96 (2H, d, J=8.8 Hz), 6.97 (2H, d, J=8.8 Hz), 7.50
(4H, 2d, J=8.8 Hz), 7.70 (1H, s); 13C-NMR (50 MHz,
CDCl3) l 55.4 (CH3), 55.5 (CH3), 114.0 (CHarom), 114.7
(CHarom), 118.8 (CH), 122.8 (Carom), 125.0 (Carom),
127.0 (CHarom), 131.1 (CHarom), 142.5 (C), 143.5 (C),
159.6 (C), 160.3 (Carom), 160.7 (Carom).
5.6. Characterization of 2,5-disubstituted thiophenes 8
8a. Isolated yield: 30%; yellow solid; m.p.=89°C;
1H-NMR (200 MHz, CDCl3) l 7.39 (1H, d, J=4 Hz),

L. La6enot et al. / Journal of Organometallic Chemistry 567 (1998) 49–55
55
7.40 (2H, dd, J=7.1 Hz and J=8.1 Hz), 7.42 (1H, dd,
J=1 Hz and J=8.1 Hz), 7.66 (2H, dd, J=7.1 Hz and
J=1 Hz), 7.72 (1H, d, J=4 Hz), 9.88 (1H, 1s); 13C-
for
C12H6F3NS
(M+):
253.0173058,
found:
253.0151000.
8f. Isolated yield: 81%; yellow solid; m.p.=48°C;
1H-NMR (200 MHz, CDCl3) l 7.12 (1H, d, J=3.9
Hz), 7.48 (1H, m), 7.60 (3H, m), 7.80 (1H, m); 13C-
NMR (50 MHz, CDCl3) l 110.4 (C), 113.9 (CN), 123.6
NMR (50 MHz, CDCl3)
l 124.1 (CH), 126.4
(CHarom), 129.2 (CHarom), 129.4 (Carom), 133.0
(Carom), 137.4 (CH), 142.5 (C), 154.3 (C), 182.8
(CHO); HRMS calc. for C11H8OS (M+): 188.0295868,
found: 188.0296000. Compound 8a is known see Ref.
[12].
1
3
(CF3, q, JCF=272 Hz), 126.8 (CHarom, q, JCF=5.4
4
Hz), 128.3 (CHarom, q, JCF=2.5 Hz), 129.4 (Carom,
2
3
q, JCF=30 Hz), 129.6 (CH), 130.9 (Carom, q, JCF
=
8b. Isolated yield: 77%; brown solid; m.p.=105.5°C;
1H-NMR (200 MHz, CDCl3) l 3.83 (3H, s), 6.93 (2H,
d, J=8.1 Hz), 7.14 (1H, d, J=3.9 Hz), 7.50 (2H, d,
J=8.1 Hz), 7.62 (1H, d, J=3.9 Hz); 13C-NMR (50
MHz, CDCl3) l 55.5 (CH3), 106.9 (C), 109.9 (CN),
114.7 (CHarom), 122.2 (CH), 125.0 (Carom), 127.8
(CHarom), 138.5 (CH), 151.9 (C), 160.7 (Carom);
HRMS calc. for C12H9NOS (M+): 215.0404858, found:
215.0409000.
8c. Isolated yield: 77%; yellow solid; m.p.=76°C;
1H-NMR (200 MHz, CDCl3) l 7.24 (1H, d, J=3.8
Hz), 7.54 (4H, m), 7.70 (1H, d, J=3.8 Hz), 7.93 (2H,
m), 8.07 (1H, m); 13C-NMR (50 MHz, CDCl3) l 109.4
(CN), 114.2 (C), 124.8 (Carom), 125.2 (Carom), 125.6
(CH), 126.5 (Carom), 127.2 (Carom), 127.6 (Carom),
128.6 (Carom), 129.7 (Carom), 129.9 (Carom), 131.3
(Carom), 133.8 (Carom), 137.6 (CH), 149.6 (C); HRMS
calc. for C15H9NS (M+): 235.0455712, found:
235.046600.
1.9 Hz), 131.8 (CHarom), 133.0 (CHarom), 137.2(CH),
147.1(C); HRMS calc. for C12H6F3NS (M+):
253.0173057, found: 253.0182000.
8g. Isolated yield: 63%; yellow solid; m.p.=88°C;
1H-NMR (200 MHz, CDCl3) l 7.27 (1H, d, J=4 Hz),
7.42 (2H, dd, J=5.4 Hz and J=4.5 Hz), 7.47 (1H, dd,
J=4.5 Hz and J=2.7 Hz), 7.58 (1H, d, J=4 Hz), 7.59
(2H, dd, J=5.4 Hz and J=2.7 Hz); 13C-NMR (50
MHz, CDCl3) l 108.3 (C), 114.4 (CN), 123.4 (CH),
126.5 (CHarom), 129.4 (CHarom), 129.5 (Carom),
132.3 (Carom), 138.5 (CH), 151.9 (C).
References
[1] J. Roncali, Chem. Rev. 92 (1992) 711, ibid 97 (1997) 173.
[2] M. Lemaire, R. Garreau, F. Garnier, J. Roncali, New J. Chem.
11 (1987) 703.
[3] (a) A.R. Martin, Y. Yang, Acta. Chem. Scand. 47 (1993) 221. (b)
N. Miyaura, N. Suzuki, Chem. Rev. 95 (1995) 2457.
[4] K. Tamao, S. Kodama, I. Nakajiama, M. Kumada, Tetrahedron
38 (1982) 3347.
[5] J.K. Stille, Angew. Chem. Int. Ed. Engl. 25 (1986) 508.
[6] L.L. Miller, Y. Yu, J. Org. Chem. 60 (1995) 6813.
[7] A. de Meijere, F.E. Meyer, Angew. Chem. Int. Ed. Engl. 33
(1994) 2379.
[8] C. Gozzi, L. Lavenot, K. Ilg, V. Penalva, M. Lemaire, Tetrahe-
dron Lett., accepted.
8d. Isolated yield: 37%; orange solid; m.p.=135°C;
1H-NMR (200 MHz, CDCl3) l 3.86 (3H, s), 6.96 (2H,
d, J=8.9 Hz), 7.13 (1H, d, J=4.3 Hz), 7.57 (2H, d,
J=8.9 Hz), 7.88 (1H, d, J=4.3 Hz); 13C-NMR (50
MHz, CDCl3)
l 55.5 (CH3), 114.2 (C), 114.9
(CHarom), 121.2 (CH), 124.8 (Carom), 127.8
(CHarom), 130.0 (CH), 152.5 (C), 161.3 (Carom);
HRMS calc. for C11H9NO3S (M+): 235.0303151,
found: 235.0319000.
8e. Isolated yield: 79%; yellow solid; m.p.=108°C;
1H-NMR (200 MHz, CDCl3) l 7.36 (1H, d, J=4.0
Hz), 7.63 (1H, d, J=4.0 Hz), 7.71 (4H, s); HRMS calc.
[9] T. Jeffery, Tetrahedron 52 (1996) 10113.
[10] T. Satoh, T. Itaya, M. Miura, M. Nomura, Chem. Lett. (1996)
823.
[11] G. Gronowitz, Acta Chem. Scand. 26 (1972) 1851.
[12] H. Gronowitz, Chem. Scr. 10 (1976) 90.
.
.