Aromatic C-H borylation catalyzed by iridium/2,6-diisopropyl-N-(2- pyridylmethylene)aniline complex

Article abstract of DOI:10.1002/adsc.200404179

The C-H borylation of aromatic and heteroaromatic compounds, such as benzene, 1,3-dichlorobenzene, 1,3-bis(trifluoromethyl)benzene, 2,6-dichloropyridine, indole, benzothiophene and benzofuran, by bis(pinacolato)diboron or pinacolborane was catalyzed by a 1/2 [IrCl(COD)] ₂-2,6-diisopropyl-N-(2-pyridylmethylene)aniline complex. The isopropyl groups of the ligand are essential for obtaining the products in high yield. Octane was a suitable solvent for the reactions of the above compounds except for indole. In the case of indole, DME was better than octane and the yield tended to improve with a smaller amount of the catalyst.

Full text of DOI:10.1002/adsc.200404179

COMMUNICATIONS
ꢀ
Aromatic C H Borylation Catalyzed by
Iridium/2,6-Diisopropyl-N-(2-pyridylmethylene)aniline Complex
Tsuyosi Tagata, Mayumi Nishida*
Koei Chemical Company, Ltd., Kitasode, Sodegaura, Chiba 299-0266, Japan
Fax: (þ81)-438-63-6876, e-mail: m-nishida@koeichem.co.jp
Received: June 16, 2004; Accepted: September 15, 2004
ꢀ
Abstract: The C H borylation of aromatic and hetero-
aromatic compounds, such as benzene, 1,3-dichloro-
benzene, 1,3-bis(trifluoromethyl)benzene, 2,6-di-
chloropyridine, indole, benzothiophene and benzo-
furan, by bis(pinacolato)diboron or pinacolborane
was catalyzed by a 1/2 [IrCl(COD)]2-2,6-diisoprop-
yl-N-(2-pyridylmethylene)aniline complex. The iso-
propyl groups of the ligand are essential for obtain-
ing the products in high yield. Octane was a suitable
solvent for the reactions of the above compounds ex-
cept for indole. In the case of indole, DME was bet-
ter than octane and the yield tended to improve with
a smaller amount of the catalyst.
has also been recently reported.[4] The Miyaura–Hart-
wig team reported that when excess benzene substrate
was heated with bis(pinacolato)diboron or pinacolbor-
ane at 808C for 16 hours in the presence of a mixture
of [IrCl(COD)]2 and bipyridine, the product was ob-
tained in good yield.[5] We were interested in the diimine
moiety of bipyridine. Thus, the feasibility of three types
ꢀ
of compounds with a diimine moiety (Types I III) as a
ligand was tested under the conditions mentioned
ꢀ
above. We report here aromatic C H borylation cata-
lyzed by a 1/2 [IrCl(COD)]2-2,6-diisopropyl-N-(2-pyri-
dylmethylene)aniline complex.
Table 1 shows that Type II was the most promising li-
gand (runs 4–6). Therefore, the influence of the R group
(Type II) on the reaction was studied.
To study the electronic effects of the ligand, a methoxy
group or a bromide was introduced to the phenyl ring of
2b (Table 2, runs 1 and 2). However, 2d and 2e gave the
products in 14% yield, which was almost the same yield
as was observed in the reaction with 2b (Table 1, run 5).
Although a mono-alkyl substituent did not improve the
ꢀ
Keywords: aromatic C H borylation; bis(pinacolato)-
diboron; 2,6-diisopropyl-N-(2-pyridylmethylene)ani-
line; iridium complex; pinacolborane
Aryl- and heteroarylboron compounds are versatile syn- yield (Table 2, runs 3–7), a 2,6-dialkyl substitution suc-
thons in organic synthesis, especially Suzuki–Miyaura
coupling.[1] There are some well-known synthetic proce-
dures that involve the borylation of lithium intermedi-
ꢀ
ꢀ
Table 1. Influence of ligands of Types I III on the C H bor-
ylation of benzene.
ates, which are produced by lithium-halogen exchange
of aromatic halides[2] or directed ortho-metallation reac-
tions.[3] In addition to these traditional methods, the di-
ꢀ
rect borylation of arenes by C H activation reactions
Run Ligand Type
R
Yield [%][a]
1
2
3
4
5
6
7
8
9
1a
1b
1c
2a
2b
2c
3a
3b
3c
Type I
Type I
Type I
Type II
Type II
Type II
Cy
Ph
9
5
5
27
17
2,6-dimethylphenyl
Cy
Ph
2,6-dimethylphenyl 50
Type III Cy
Type III Ph
Type III 2,6-dimethylphenyl
5
6
5
[a]
Yield was determined by GC. The internal standard was
ꢀ
Scheme 1. Ligands of Types I III.
4,4’-dimethylbiphenyl.
Adv. Synth. Catal. 2004, 346, 1655–1660
DOI: 10.1002/adsc.200404179
ꢀ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1655

Tsuyosi Tagata, Mayumi Nishida
COMMUNICATIONS
ꢀ
Table 2. C H borylation using ligand Type II.
12), where the reaction was conducted in octane accord-
ing to the conditions reported by Miyaura and Ishiya-
ma.[6]
However, when the reaction ofindole with bis(pinaco-
lato)diboron was carried out in octane, the product was
obtained in only 1% yield (Table 4, run 1). To identify
better conditions, we examined DME, DMF, and mesi-
tylene as possible solvents. Miyaura and Ishiyama re-
ported that a non-polar solvent was suitable for this re-
action.[7] The reactivity in different solvents was in the
order hexane>mesitylene>DME>DMF. However,
among the solvents we tested, DME gave a relatively
good yield (Table 4, runs 1–4). When the ratio of bis(pi-
nacolato)diboron to indole was changed from 1:4 to
1:2, the yield was increased to 30% (Table 4, run 5). Sur-
prisingly, a smaller amount of the catalyst dramatically
improved the yield. When 0.2 mol % of catalyst was
used in the reaction, the product was obtained in 91%
yield (Table 4, run 7). However, 0.02 mol % of catalyst
was too little for the reaction to take place (Table 4,
run 8).
To clarify the role of the ligand, two experiments were
conducted. First, the reaction was carried out without a
ligand. When a mixture of indole, bis(pinacolato)dibor-
on, and [IrCl(COD)]2 (0.1 mol %) was heated in DME,
the product was not obtained. Second, we tested the fea-
sibility of the product as a ligand. When a mixture of in-
dole, bis(pinacolato)diboron, [IrCl(COD)]2 (0.1 mol %)
and 4a (0.2 mol %) was heated in DME, the product was
again not produced. These results showedthat the ligand
was essential for this reaction and the product did not act
Run Ligand
A
B
C
D
E
Yield [%][a]
1
2
3
2d
2e
2f
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Et
OMe
Br
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
14
14
21
19
20
16
19
32
74
Me
Et
i-Pr
t-Bu
Ph
Et
i-Pr i-Pr
i-Pr i-Pr
i-Pr i-Pr
4
5
6
2g
2h
2i
7
2j
8
2k
9
2l
10
11
12
13
14
2m
2n
2o
2p
2q
Me 21
Ph 39
H
H
Me i-Pr i-Pr
Br i-Pr i-Pr
78
11
14
[a]
Yield was determined by GC. The internal standard was
4,4’-dimethylbiphenyl.
cessfully increased the yield (Table 1, run 6, and Table 2, as a ligand. The detailed mechanism has not yet been
runs 8 and 9). In the reaction with 2l, the yield was as clarified.
high as 74% (Table 2, run 9). On the other hand, ligands
The tendency for a smaller amount of catalyst to be as-
2 m and 2n, which had a methyl group or phenyl group at sociated with an improved yield was not observed when
position E, gave the product in a low yield (Table 2, octane was used as a solvent. In fact, the reaction in the
runs 10and 11). While a methyl group at the 6-position
of pyridine in 2o slightly increased the yield (Table 2, unsatisfactory conversion (Table 4, run 9).
run 12), a bromide at this position, as in 2p, decreased When the reaction with pinacolborane in the presence
presence of 0.2 mol % of catalyst in octane resulted in
the yield (Table 2, run 13). When the reaction was con- of 1.5 mol % catalyst was carried out in DME, the prod-
ducted with 2q, which had a quinoline moiety, the yield uct was obtained in 80% yield (Table 4, run 10). As was
decreased. The reaction may be impairedby the poorco- seen in the reaction with bis(pinacolato)diboron,
ordination ability of ligands 2p and 2q. Among the li- 0.1 mol % of catalyst improved the yield to 92% (Ta-
gands tested above, 2l and 2o gave good results. Thus, ble 4, run 11), and 0.01 mol% of catalyst gave the prod-
we used 2l and 2o in the reactions of other substrates uct in only 15% yield (Table 4, run 12). On the other
with pinacolborane.
A mixture of benzene (60mmol), pinacolborane
hand, with octane as a solvent, 1.5 mol % and
0.1 mol % of catalyst gave the product in respective
(2 mmol), [IrCl(COD)]2 (0.015 mmol), and ligand yields of 65% and 72% (Table 4, runs 13 and 14). In
(0.03 mmol) was stirred at 808C for 12 h. Both 2 l and the case of indole, pinacolborane gave a higher yield
2o gave the products in 79% yield (Table 3, runs 1 and than bis(pinacolato)diboron.
2). In the reaction of 1,3-dichlorobenzene, both bis(pi-
We wondered if the same tendency would be observed
nacolato)diboron and pinacolborane gave the product in the reaction with a 1/2 [IrCl(COD)]2-bipyridine sys-
in over 80% yield (Table 3, runs 3 and 4). When 1,3-bis- tem in DME.[8] As shown in Table 5, DME was a better
(trifluoromethyl)benzene was used as a substrate, pina- solvent than octane (Table 5, runs 1, 3, 4 and 6) and a
colborane gave a higher yield than bis(pinacolato)dibor- smaller amount of catalyst gave a slightly higher yield
on (Table 3, runs 5–8). The same trend was observed in in DME (Table 5, runs 1, 2, 4 and 5). These trends are
the reaction of 2,6-dichloropyridine (Table 3, runs 9– the same as those observed in the reaction of indole
1656
ꢀ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
Adv. Synth. Catal. 2004, 346, 1655–1660

ꢀ
Aromatic C H Borylation
COMMUNICATIONS
Table 3. Reactions with pinacolborane.
Run
Substrate
X
Ligand
Pin2B2 or PinBH
Product 4
Yield [%]
Y
1
2
3
4
5
6
7
8
9
H
H
Cl
Cl
CF3
CF3
CF3
CF3
Cl
C
C
C
C
C
C
C
C
N
2l
2o
2l
2l
2l
2o
2l
2o
2l
2o
2l
PinBH
PinBH
Pin2B2
PinBH
Pin2B2
Pin2B2
PinBH
PinBH
Pin2B2
Pin2B2
PinBH
PinBH
4a
4a
4b
4b
4c
4c
4c
4c
4d
4d
4d
4d
79[a]
79[a]
83[b]
85[b]
47[a]
6[a]
73[a]
70[a]
73[b]
71[b]
93[b]
90[b]
10Cl
11
12
N
Cl
Cl
N
N
2o
[a]
Yields were determined by GC. The internal standard was 4,4’-dimethylbiphenyl.
Yields were determined by GC. The internal standard was 4,4’-di-t-butylbipyridine.
[b]
with 1/2 [IrCl(COD)]2-2,6-diisopropyl-N-(2-pyridylme- [IrCl(COD)]2-2a (Table 1, run 4), in both cases the
thylene)aniline. yields were improved from 27% to 60% (Table 6). It
We continued to examine the reactions with 1/2 [IrCl(- seemed that steric bulkiness around the imine moiety
COD)]2-2 l. In the reactions of benzothiophene with is important for obtaining the product in high yield.
bis(pinacolato)diboron or pinacolborane, octane was a Therefore, 6-diisopropyl-N-(2-pyridylmethylene)ani-
better solvent than DME (Table 4, runs 15–20). Al- line was also effective.
though the reactions of benzothiophene with bis(pina-
In conclusion, a 1/2 [IrCl(COD)]2-2,6-diisopropyl-N-
colato)diboron in DME (Table 4, runs 15 and 16) did (2-pyridylmethylene)aniline complex catalyzed the
ꢀ
not proceed smoothly, the product was obtained in C H borylation of aromatic and heteroaromatic com-
86% yield in octane (Table 4, run 17). Pinacolborane pounds. The isopropyl groups of 2,6-diisopropyl-N-(2-
in DME gave a better yield than bis(pinacolato)diboron pyridylmethylene)aniline are indispensable for obtain-
(Table 4, runs 18 and 19). The reaction with pinacolbor- ing the products in high yield. In the reactions of ben-
ane in octane gave the product in 94% yield (Table 4, zene, 1,3-bis(trifluoromethyl)benzene, and 2,6-dichloro-
run 20).
pyridine in octane, pinacolborane gave a better yield
In the reaction of benzofuran, octane again acted as a than bis(pinacolato)diboron. In the reactions of benzo-
good solvent. Unfortunately, in this case, a regioisomer, thiophene and benzofuran, octane was also a better sol-
which was determined by GC-MS, was found (Table 4, vent than DME, which was consistent with the reactivity
runs 21–26). The reaction with bis(pinacolato)diboron reported by Miyaura and Ishiyama. However, in the re-
in the presence of 3 mol % of catalyst in octane gave action of indole, DME was the most suitable solvent and
the product in 74% yield with 10% of the isomer (Ta- the yield was improved with a smaller amount of cata-
ble 4, run 23). However, the reaction with pinacolbor- lyst. The reason for this trend is under investigation.
ane in octane gave 74% yield with 1% of isomer (Ta-
ble 4, run 26). In the reaction of benzofuran, pinacolbor-
ane resulted in higher yield and selectivity compared to
bis(pinacolato)diboron.
Experimental Section
Finally, to examine the steric effects of the imine moi-
ety, ligand 2r or 2s was used in the reaction. Compared to
All reactions were conducted under a nitrogen atmosphere.
NMR spectra were recorded in CDCl3 (1H at 400 MHz and
the results obtained in the reaction catalyzed by 1/2 13C at 100 MHz). All starting materials, reagents and solvents
Adv. Synth. Catal. 2004, 346, 1655–1660
asc.wiley-vch.de
ꢀ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1657

Tsuyosi Tagata, Mayumi Nishida
COMMUNICATIONS
Table 4. Reactions of indole with 1/2 [IrCl(COD)]2-2l.
Run
Z
Solvent
Pin2B2 or
PinBH
Borane:Substrate
(mole ratio)
1/2 [IrCl(COD)]2-2 l
(mol %)
Yield
[%][a]
1
2
3
4
5
6
7
8
9
NH
NH
NH
NH
NH
NH
NH
NH
NH
octane
mesitylene
DMF
DME
DME
DME
DME
DME
octane
Pin2B2
Pin2B2
Pin2B2
Pin2B2
Pin2B2
Pin2B2
Pin2B2
Pin2B2
Pin2B2
1: 4
1: 4
1: 4
1: 4
1: 2
1: 2
1: 2
1: 2
1: 2
3
3
3
3
3
1
1
7
1
15
30
37
91
1
0.2
0.02
0.2
5
10NH
11
12
13
14
15
16
17
18
19
20S
21
22
23
24
25
26
DME
PinBH
1: 1
1.5
80
NH
NH
NH
NH
S
DME
DME
octane
octane
DME
DME
octane
DME
DME
PinBH
PinBH
PinBH
PinBH
Pin2B2
Pin2B2
Pin2B2
PinBH
PinBH
1: 1
1: 1
1: 1
1: 1
1: 2
1: 2
1: 2
1: 1
1: 1
0.1
0.01
1.5
0.1
3
0.2
3
1.5
0.1
92
15
65
72
1
S
S
S
S
1
86
59
77
octane
PinBH
1: 1
1.5
94
O
O
O
O
O
O
DME
DME
octane
DME
DME
octane
Pin2B2
Pin2B2
Pin2B2
PinBH
PinBH
PinBH
1: 2
1: 2
1: 2
1: 1
1: 1
1: 1
3
0.2
3
1.5
0.1
1.5
62 (14[b]
)
1 (trace[b]
)
74 (10[b]
)
74 (1[b]
77 (2[b]
82 (1[b]
)
)
)
[a]
Yields were determined by GC. The internal standard was 4,4’-di-t-butylbipyridine.
The yield of the isomer was determined by GC-MS.
[b]
Table 5. Reaction of indole with 1: 2 [IrCl(COD)]2-bipyridine.
Run
Ligand
Solvent
Pin2B2 or
PinBH
Borane :Substrate
(mole ratio)
1: 2 [IrCl(COD)]2-Ligand
(mol %)
Yield
[%][a]
1
2
3
4
5
6
6b
6a
6a
6a
6a
6a
DME
DME
octane
DME
DME
octane
Pin2B2
Pin2B2
Pin2B2
PinBH
PinBH
PinBH
1: 2
1: 2
1: 2
1: 1
1: 1
1: 1
3
0.2
3
1.5
0.1
1.5
87
92
60
67
92
1
[a] Yields were determined by GC. The internal standard was 4,4’-di-t-butylbipyridine.
1658
ꢀ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
Adv. Synth. Catal. 2004, 346, 1655–1660

ꢀ
Aromatic C H Borylation
COMMUNICATIONS
ꢀ
Table 6. C H borylation using ligand Type II.
was determined by GC. The internal standard was 4,4’-di-t-bu-
tyl-2,2’-bipyridine. Compound 4d[4d] is described in the litera-
ture.
Reactions of 2,6-Dichloropyridine with Pinacolborane
in Table 3
A 50-mL tube fitted with a magnetic stirring bar, septum inlet,
and condenser was charged with 2,6-dichloropyridine (1.48 g,
10mmol), [IrCl(COD)] 2 (50.3 mg, 0.075 mmol) and ligand 2k
or 2n (0.15 mmol), and then flushed with argon. Octane
(25 mL) and pinacolborane (1.28 g, 10mmol) were then add-
ed, and the mixture was stirred at 808C for 12 h. The yield
was determined by GC. The internal standard was 4,4’-di-t-bu-
tyl-2,2’-bipyridine.
Run
Ligand
Yield [%][a]
1
2
2r
2s
60
60
[a]
Yield was determined by GC. The internal standard was
4,4’-dimethylbiphenyl.
Reactions of Indole, Benzothiophene and Benzofuran
with Bis(pinacolato)diboron or Pinacolborane in
Table 4
were of commercial grade. All products were known com-
pounds, and identified based on their NMR and GC-mass spec-
tra.
Borylation of indole, benzothiophene and benzofuran was car-
ried out according to the procedure for the reactions of 2,6-di-
chloropyridine in Table 3. Besides octane, the other solvents
shown in Table 4 were also used in the reaction. The amounts
of [IrCl(COD)]2, ligand 2 l, and starting material are also
shown in Table 4. Compounds 5a,[6] 5b,[6] and 5c[6] are described
in the literature.
Reactions of Benzene with Bis(pinacolato)diboron in
Tables 1, 2, and 6, and of 1,3-Dichlorobenzene or 1,3-
Bis(trifluoromethyl)benzene with Bis(pinacolato)-
diboron in Table 3
A 20-mL tube fitted with a magnetic stirring bar, septum inlet,
and condenser was charged with [IrCl(COD)]2 (10.1 mg,
0.015 mmol), ligand (0.03 mmol), and bis(pinacolato)diboron
(254 mg, 1.0mmol), and then flushed with argon. The substrate
(60mmol) was added, and the mixture was stirred at 80 8C for
12 h. The yield was determined by GC. The internal standard
was 4,4’-dimethylbiphenyl. Compounds 4a,[5] 4b,[4j] and 4c[4c]
are described in the literature.
Reactions of Indole with Bis(pinacolato)diboron or
Pinacolborane in the Presence of 1/2 [IrCl(COD)]2-
Bipyridyl in Table 5
Borylation of indole was carried out according to the proce-
dure for the reactions of 2,6-dichloropyridine in Table 3. Be-
sides ligand 2l, 6a and 6b were also used as a ligand. The
amounts of [IrCl(COD)]2, ligand, and starting material are
also shown in Table 5.
Reactions of Benzene, 1,3-Dichlorobenzene and 1,3-
Bis(trifluoromethyl)benzene with Pinacolborane in
Table 3
Acknowledgements
The authors are grateful for the assistance of Mr. Akira Torii.
A 20-mL tube fitted with a magnetic stirring bar, septum inlet,
and condenser was charged with [IrCl(COD)]2 (10.1 mg,
0.015 mmol) and ligand (0.03 mmol), and then flushed with ar-
gon. The substrate (60mmol) and pinacolborane (256 mg,
2.0mmol) were added, and the mixture was stirred at 80 8C
for 12 h. The yield was determined by GC. The internal stand-
ard was 4,4’-dimethylbiphenyl.
References and Notes
[1] a) A. Suzuki, Acc. Chem. Res. 1982, 15, 178; b) A. Suzuki,
Pure Appl. Chem. 1985, 57, 1749; c) A. Suzuki, Pure Appl.
Chem. 1991, 63, 419; d) A. Suzuki, Pure Appl. Chem. 1994,
66, 213; e) N. Miyaura, A. Suzuki, Chem. Rev. 1995, 95,
2457; f) V. Snieckus, Chem. Rev. 1990, 90, 879; g) D. S.
Matteson, Tetrahedron 1989, 45, 1859; h) N. Miyaura, K
Yamada,. A. Suzuki, Tetrahedron Lett. 1979, 20, 3437;
i) N. Miyaura, T. Yanagi, A. Suzuki, Synth. Commun.
1981, 11, 513; j) S. Saito, M. Sakai, N. Miyaura, Tetrahe-
dron Lett. 1996, 37, 2993.
Reactions of 2,6-Dichloropyridine with
Bis(pinacolato)diboron in Table 3
A 20-mL tube fitted with a magnetic stirring bar, septum inlet,
and condenser was charged with 2,6-dichloropyridine (296 mg,
2.0mmol), [IrCl(COD)] 2 (10.1 mg, 0.015 mmol), ligand 2 l or
2o (0.03 mmol), and bis(pinacolato)diboron (254 mg,
1.0mmol), and then flushed with argon. Octane (5 mL) was
added, and the mixture was stirred at 808C for 12 h. The yield
[2] a) M. K. Manthy, S. G. Truscott, J. W. Truscott, J. Org.
Chem. 1990, 55, 4581–4585; b) J. A. Bryant, R. C. Helge-
Adv. Synth. Catal. 2004, 346, 1655–1660
asc.wiley-vch.de
ꢀ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1659

Tsuyosi Tagata, Mayumi Nishida
COMMUNICATIONS
son, C. B. Knobler, P. P. DeGrandpre, D. J. Cram, J. Org.
Chem. 1990, 55, 4622–4634; c) R. C. Helgeson, B. P.
Czech, E. Chapoteau, C. R. Gebauer, K. Anaud. D. J.
Cram, J. Am. Chem. Soc. 1989, 111, 6339–6350; d) Y. Ya-
mamoto, T. Seco, H. Nemoto, J. Org. Chem. 1989, 54,
4734–4736; e) U. Schmidt, R. Meyer, V. Leitenberger,
A. Lieberknecht, Angew. Chem. 1989, 101, 946–948;
f) T. Iihama, J. M. Fu, M. Bourguignon, V. Snieckus, Syn-
thesis 1989, 3, 184–188; g) M. E. Jung, Y. H. Young, Tetra-
hedron Lett. 1988, 29, 2517–2520.
eczka Jr., M. R. Smith III, Science 2002, 295, 305–308;
e) H. Chen, S. Schlecht, T. C. Semple, J. F. Hartwig, Sci-
ence 2000, 287, 1995; f) H. Chen, S. Schlecht, T. C. Semple,
J. F. Hartwig, Angew. Chem. Int. Ed. 1999, 38, 3391–3393;
g) S. Shimada, A. S. Batsanov, J. A. K. Hward, T. B. Mard-
er, Angew. Chem. Int. Ed. 2001, 40, 2168–2171; h) T. Ish-
iyama, N. Miyaura, J. Organomet. Chem. 2003, 680, 3–11
and references cited therein; i) T. Ishiyama, N. Miyaura,
The Chemical Record 2004, 3, 271–280and references cit-
ed therein; j) T. Ishiyama, J. Takagi, J. F. Hartwig, N.
Miyaura, Angew. Chem. Int. Ed. 2002, 41, 3056–3058.
[5] T. Ishiyama, J. Takagi, K. Ishida, N. Miyaura, N. R. Anas-
tasi, J. F. Hartwig, J. Am. Chem. Soc. 2002, 124, 390–391.
[6] J. Takagi, K. Sato, J. F. Hartwig, T. Ishiyama, N. Miyaura,
Tetrahedron Lett. 2002, 43, 5649–5651.
[3] a) A. Godard, F. Marsais, N. Ple, F. Trecourt, A. Turck,
Heterocycles 1995, 2, 1055–1091 and references cited
therein; b) G. Queguiner, F. Marsais, V. Snieckus, J. Ep-
sztajn, Adv. Hetterocycl. Chem. 1991, 52, 187–304 and ref-
erences cited therein; c) F. Marsais, A. Godard, G. Que-
guiner, J. Hetetocyclic Chem. 1989, 26, 1589.
[4] a) C. N. Iverson, M. R. Smith III, J. Am. Chem. Soc. 1999,
121, 7696–7697; b) J.-Y. Cho, C. N. Iverson, M. R. Smith
III, J. Am. Chem. Soc. 2000, 122, 12868–12869; c) M. K.
Tse, J.-Y. Cho, M. R. Smith III, Org. Lett. 2001, 3,
2831–2833; d) J.-Y. Cho, M. K. Tse, D. Holmes, R. E. Mal-
[7] T. Ishiyama, Y. Nobuta, J. F. Hartwig, N. Miyaura, Chem.
Commun. 2003, 2824–2926.
[8] It was reported that the product was obtained in 92%
yield, when 6b was used as a ligand instead of 6a in run
3.[6] Although we carried out the same reaction, the prod-
uct was obtained in only 58% yield.
1660
ꢀ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
Adv. Synth. Catal. 2004, 346, 1655–1660