Synthesis of biaryls through a one-pot tandem borylation/Suzuki-Miyaura cross-coupling reaction catalyzed by a palladacycle

Article abstract of DOI:10.1002/ejoc.201101409

The tricyclohexylphosphane adduct of cyclopalladated ferrocenylimine I exhibited high catalytic activity in the one-pot borylation/Suzuki-Miyaura coupling (BSC) reaction with low catalyst loading (2 mol-%). Various biaryls were obtained in good to excellent yields for 37 examples. This process was applied to aryl and heteroaryl halides (Br and Cl) containing a variety of functional groups and did not require an excess amount of phosphane ligand and the addition of the palladium catalyst in the second step. Cyclopalladated ferrocenylimine I exhibited high catalytic activity in the borylation/Suzuki- Miyaura coupling (BSC) reaction with low catalyst loading. Various unsymmetrical biaryls were obtained ingood to excellent yields in one pot. This protocol was applied to aryl and heteroaryl halides (Br and Cl) containing a variety of functional groups without adding catalyst in the second step. Copyright

Full text of DOI:10.1002/ejoc.201101409

FULL PAPER
DOI: 10.1002/ejoc.201101409
Synthesis of Biaryls through a One-Pot Tandem Borylation/Suzuki–Miyaura
Cross-Coupling Reaction Catalyzed by a Palladacycle
Lianhui Wang,[a,b] Xiuling Cui,*[a] Jingya Li,[b] Yusheng Wu,[b] Zhiwu Zhu,[a] and
Yangjie Wu*[a]
Keywords: Cross-coupling / Halides / Borylation / Palladium / Biaryls
The tricyclohexylphosphane adduct of cyclopalladated ferro-
cenylimine I exhibited high catalytic activity in the one-pot
borylation/Suzuki–Miyaura coupling (BSC) reaction with low
catalyst loading (2 mol-%). Various biaryls were obtained in
good to excellent yields for 37 examples. This process was
applied to aryl and heteroaryl halides (Br and Cl) containing
a variety of functional groups and did not require an excess
amount of phosphane ligand and the addition of the palla-
dium catalyst in the second step.
yaura et al.[3] reported the first palladium-catalyzed one-pot
borylation/Suzuki–Miyaura coupling (BSC) reaction for the
synthesis of unsymmetrical biaryls, which involved con-
verting an aryl triflate in situ into a boronate ester followed
by the addition a second aryl triflate along with the palla-
dium catalyst and base. Since then, the development of
catalytic C–H[4] or C–X[5–7] borylation/Suzuki–Miyaura
coupling processes in one pot has allowed for the prepara-
tion of unsymmetrical biaryls. This protocol has been ap-
plied to the syntheses of pharmaceuticals.[8] However, a
high loading of catalyst (5–10 mol-%) and the addition of
a second portion of the palladium catalyst are necessary.
Introduction
Functionalized biaryls are important components of many
medicinals and are employed as organic conductors or li-
gands for asymmetric catalysis.[1] The palladium-catalyzed
Suzuki–Miyaura cross-coupling reaction of arylboronic ac-
ids or -boronates with aryl halides has shown to be the most
common method to build such structures.[2] However, it is
usually essential to prepare and isolate arylboronic acids
or -boronate esters that are not commercially available prior
to the coupling reaction, especially arylboronic acids or -
boronate esters, which have complicated structures. Mi-
Scheme 1. Palladium-catalyzed BSC coupling reaction.
Recently, Buchwald et al.[9] reported that Pd2(dba)3 and
XPhos actively combine to catalyze efficiently the one-pot
BSC reaction without adding a second portion of the
[a] Department of Chemistry, Henan Key Laboratory of Chemical
Biology and Organic Chemistry, Key Laboratory of Applied
Chemistry of Henan Universities Zhengzhou University,
Zhengzhou 450052, P. R. China
catalyst
prior
to
conducting
the
Suzuki–
E-mail: cuixl@zzu.edu.cn
Miyaura reaction. In this process, an excess amount of the
phosphane ligand (P/Pd, 4:1) was required.
In our laboratory, we found that cyclopalladated ferro-
cenylimine I was successfully employed in the borylation
wyj@zzu.edu.cn
[b] Tetranov Biopharm, Inc.
Zhengzhou 450052, P. R. China
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201101409.
Eur. J. Org. Chem. 2012, 595–603
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
595

L. Wang, X. Cui, J. Li, Y. Wu, Z. Zhu, Y. Wu
FULL PAPER
of aryl halides and the one-pot BSC reaction to synthesize
Under the optimized reaction conditions (Table 1, En-
symmetrical biaryls.[10] Herein, we employ cyclopalladated try 2) and by using bromobenzene (1a) as the aryl halide,
ferrocenylimine I as a catalyst in the one-pot BSC reaction the scope of the substrates b was investigated. The total
to synthesize unsymmetrical biaryls without an excess yields for the borylation/Suzuki–Miyaura reactions depend
amount of phosphane ligand and the addition of catalyst mainly on the Suzuki–Miyaura coupling, as bromobenzene
in the second step. The results reveal that palladacycle I not (1a) can be quantitatively converted into the boronate ester.
only effected a highly efficient borylation reaction, but also As illustrated in Table 2, I exhibited high catalytic activity
maintained its catalytic activity in the subsequent Suzuki– for both aryl bromides and chlorides and tolerated a
Miyaura coupling by using only 2 mol-% of catalyst loading number of functionalities, such as nitro, cyano, acetyl, and
(Scheme 1).
amino groups. Electron-rich, electron-deficient, and rela-
tively hindered aryl bromides afforded good to excellent
yields in 3 h (Table 2, Entries 1–6). In addition, aryl chlor-
ides with both electron-withdrawing and electron-donating
groups provided unsymmetrical biaryls in moderate to ex-
cellent isolated yields when the reaction time was prolonged
to 15 h (Table 2, Entries 7–10). It is worth noting that this
protocol avoided the α-arylation reaction of ketones with
arylboronate esters (Table 2, Entries 1, 3, and 7), and a 95%
isolated yield was achieved with 3-chloroaniline (10b) with-
out the additional amino group protection (Table 2, En-
try 10).
Next, we evaluated heteroaryl halides as substrates for
the BSC procedure with bromobenzene (1a) under the stan-
dard reaction conditions. The results (see Table 3) show that
the heteroaryl halide could be employed as the substrate in
both steps. For most cases, good yields were obtained when
pyridyl bromide served as the second substrate (Table 3, En-
tries 1–8). Such a protocol was also applied to heteroaryl
chlorides. 4-Chloropicolinonitrile (18b) and 2-chloro-6-
phenylpyrazine (19b) provided the desired products in yields
of 80% and 93%, respectively (Table 3, Entries 9 and 10).
When 3-bromopyridine (Table 3, Entry 1 vs. 11), 5-
bromo-N,N-dimethylpyridin-2-amine (Table 3, Entry 2 vs.
12), and 5-bromopyridin-2-amine (Table 3, Entry 3 vs. 13)
served as substrates in the first step and the reaction time
Results and Discussion
In our previous study,[10a] the efficient reaction condi-
tions for the borylation of aryl halides catalyzed by pallada-
cycle I were well developed. Under such optimized reaction
conditions, the reaction of aryl bromides with bis(pinacol-
ato)diboron quantitatively provided the arylboronate esters
in only 2 h. In this endeavor, the one-pot borylation/
Suzuki–Miyaura coupling reaction of bromobenzene (1a)
with 1-(4-bromophenyl)ethanone (1b) was initially chosen
as a model to screen the different reaction parameters for
the second step, such as the base, solvent, and reaction time
(see Table 1). After bromobenzene was completely con-
sumed, a stronger base was required to promote the Su-
zuki–Miyaura coupling. Yields of 92%, 85%, 88%, and
90% were obtained when K3PO4, K2CO3, Cs2CO3, and Na-
OtBu were used, respectively, as the base (Table 1, En-
tries 1–4). The solvent 1,4-dioxane was suitable for both the
borylation and the Suzuki–Miyaura reactions (Table 1, En-
tries 1–5 and 10).[10a] The yield decreased to 68% from 92%
when 1.0 equiv. of bromobenzene (1a) was used (Table 1,
Entry 1 vs. 2). When the reaction time was prolonged from
3 h to 15 h, the yield did not improve significantly (Table 1,
Entry 10 vs. 2).
Table 1. Screening of bases and solvents for palladium-catalyzed BSC reaction.[a]
Entry
Base
Solvent
t [h]
Yield [%][b]
1
2
3
4
5
6
7
8
9
K3PO4
K3PO4
K2CO3
Cs2CO3
NaOtBu
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
dioxane
dioxane
dioxane
dioxane
dioxane
toluene
DMF[d]
THF[d]
3
3
3
3
3
3
3
3
3
68[c]
92
85
88
90
88
84
32
82
93
DME[d]
dioxane
10
15
[a] Reagents and conditions: bromobenzene (1a, 1.2 equiv.), 1-(4-bromophenyl)ethanone (1b, 1.0 mmol), bis(pinacolato)diborane
(1.44 equiv.), KOAc (2.4 equiv.), base (5 equiv.), solvent (2.5 mL), I [2 mol-% based on bromobenzene (1a)]. [b] Isolated yields based on
1-(4-bromophenyl)ethanone (1b). [c] The ratio of 1a/1b is 1:1. [d] DMF = dimethylformamide, THF = tetrahydrofuran, DME = 1,2-
dimethoxyethane.
596
www.eurjoc.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2012, 595–603

Biaryls through a Borylation/Suzuki–Miyaura Cross-Coupling
Table 2. Palladium-catalyzed BSC reaction of aryl halides with bromobenzene (1a).[a]
[a] Reagents and conditions: bromobenzene (1a, 1.2 equiv.), Ar–X (1.0 equiv.), bis(pinacolato)diborane (1.44 equiv.), KOAc (2.4 equiv.),
K3PO4 (5 equiv.), 1,4-dioxane (2.5 mL), I [2 mol-% based on bromobenzene (1a)]. [b] Isolated yields based on Ar–X.
was prolonged from 2 h to 6 h, the yields improved. In con- affect the yields. For example, 3-bromopyridine coupled
trast, when 5-bromo-2-methylpyridine (Table 3, Entry 4 vs. with 3-bromo-2-methylpyridine (Table 4, Entry 2) and 3-
14), 3-bromo-2-methylpyridine (Table 3, Entry 5 vs. 15), 3- bromo-4-methylpyridine (Table 4, Entry 3) gave the desired
bromo-4-methylpyridine (Table 3, Entry 6 vs. 16), and 4- products in 81% and 82% yields, respectively. 2-Bromopyr-
bromo-N-methylpyridin-2-amine (Table 3, Entry 7 vs. 17) idine and its derivatives are generally considered as less
were used as substrates in the first step, the yields decreased active substrates in both the borylation and Suzuki–Mi-
dramatically, because of the low conversion in the bor- yaura reactions. To our delight, 73% and 78% isolated
ylation step.
yields were achieved with 2-bromopyridine (20b, Table 4,
Subsequently, we investigated the BSC coupling reaction Entry 8) and 2-bromo-6-methoxypyridine (21b, Table 4, En-
between heteroaryl halides to synthesize unsymmetrical het- try 10), respectively. However, low yields were obtained
eroaryls (Table 4). In all cases, the reaction of 3-bromopyr- when indolyl, furyl, and thiophenyl bromides were utilized
idine (2a) and 4-bromo-2-methoxypyridine (3a) with pyr- as the substrates.
idyl halides functionalized by electron-withdrawing (such as
To clarify the influence of the substituent in the sub-
CN) and electron-donating groups (such as Me, MeO, and strates in the BSC reaction, control experiments were per-
NHMe) gave good to excellent yields. Moreover, bulky formed (Table 5). When 1-bromo-4-methoxybenzene (2b)
functional groups on the pyridine ring did not significantly and 1-bromo-4-(trifluoromethyl)benzene (22b) served as
Eur. J. Org. Chem. 2012, 595–603
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
597

L. Wang, X. Cui, J. Li, Y. Wu, Z. Zhu, Y. Wu
FULL PAPER
Table 3. Palladium-catalyzed BSC reaction of heteroaryl halides with aryl bromides.[a]
[a] Reagents and conditions: Ar–Br (1.2 equiv.), ArЈ–X (1.0 equiv.), bis(pinacolato)diborane (1.44 equiv.), KOAc (2.4 equiv.), K3PO4
(5 equiv.), 1,4-dioxane (2.5 mL), I (2 mol-% based on Ar–Br). [b] Isolated yield based on ArЈ–X.
598
www.eurjoc.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2012, 595–603

Biaryls through a Borylation/Suzuki–Miyaura Cross-Coupling
Table 4. Palladium-catalyzed one-pot BSC reaction of heteroaryl halides.[a]
[a] Reagents and conditions: Ar–Br (1.2 equiv.), ArЈ–X (1.0 equiv.), bis(pinacolato)diborane (1.44 equiv.), KOAc (2.4 equiv.), K3PO4
(5 equiv.), 1,4-dioxane (2.5 mL), I (2 mol-% based on Ar–Br). [b] Isolated yield based on ArЈ–X.
substrates for the first and the second step, respectively, a
Conclusions
95% yield was obtained (Table 5, Entry 2). In contrast, a
Cyclopalladated ferrocenylimine I was highly effective for
lower yield of 87% was afforded (Table 5, Entry 1) when
catalyzing the BSC reaction. Various functionalized unsym-
the experiment was changed to have 2b and 22b serve as
metrical biaryls have been obtained in good to excellent
substrates in the second and first step, respectively. These
yields in one pot with 2 mol-% loading of complex I with-
results suggest that the electron-donating group in substrate
out an excess amount of ligand and the addition of catalyst
a and an electron-withdrawing group in substrate b would
in the second step. Such methodology tolerated not only a
favor a BSC reaction catalyzed by I. Nevertheless, this rea-
number of functional groups, such as primary amines, carb-
soning did not apply to sterically hindered substrates such
onyl groups, and nitriles, but also was applied to substrates
as 23b and 6b. Compound 6b afforded the desired product
such as aryl bromides and chlorides and heteroaryl halides.
in 91% yield, when it served as the substrate in the first
step (Table 5, Entry 4), but the addition of 23b as the sub-
strate for the first step only gave a 47% yield (Table 5, En-
Experimental Section
General Methods: 1H and 13C NMR spectroscopic data were re-
corded with a Bruker DPX 400 instrument by using CDCl3 as the
try 3), because of the difficulty in forming the boronate
from sterically hindered substrates.
Eur. J. Org. Chem. 2012, 595–603
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
599

L. Wang, X. Cui, J. Li, Y. Wu, Z. Zhu, Y. Wu
FULL PAPER
Table 5. Control experiments to examine the influence of substituent in substrates on the palladium-catalyzed BSC reaction.[a]
[a] Reagents and conditions: Ar–Br (1.2 equiv.), ArЈ–Br (1.0 equiv.), bis(pinacolato)diborane (1.44 equiv.), KOAc (2.4 equiv.), K3PO4
(5 equiv.), 1,4-dioxane (2.5 mL), I (2 mol-% based on Ar–Br). [b] Isolated yield based on ArЈ–Br.
solvent and tetramethylsilane (TMS) as the internal standard. All
coupling constants (J) are reported in Hertz (Hz). Melting points
were measured with an XT4A microscopic apparatus. High-resolu-
tion mass spectra were recorded with a Waters Q-Tof micro spec-
trometer by using electrospray ionization (ESI). Preparative TLC
was performed on silica gel plates and developed with ethyl acetate/
petroleum ether. All solvents were dried according to standard
methods. Aryl halides a and b and bis(pinacolato)diborane were
obtained from commercial sources and were generally used without
further purification. Cyclopalladated ferrocenylimine I was synthe-
sized according to the reported procedure.[11,12]
δ = 7.56–7.52 (m, 4 H, Ar), 7.43–7.40 (m, 2 H, Ar), 7.32–7.30 (m,
1 H, Ar), 6.99–6.97 (m, 2 H, Ar), 3.85 (s, 3 H, CH3) ppm.
1-(Biphenyl-3-yl)ethanone (3d): Table 2, Entry 3.[15] Purified by
flash chromatography on silica gel (ethyl acetate/petroleum ether,
1
1:40) to afford a colorless oil (76 mg, 77%). H NMR (400 MHz,
CDCl3): δ = 8.17 (s, 1 H, Ar), 7.91 (d, J = 7.7 Hz, 1 H, Ar), 7.76
(d, J = 7.7 Hz, 1 H, Ar), 7.60 (d, J = 8.3 Hz, 2 H, Ar), 7.51 (t, J
= 7.7 Hz, 1 H, Ar), 7.45 (t, J = 7.3 Hz, 2 H, Ar), 7.36 (t, J =
7.3 Hz, 1 H, Ar), 2.63 (s, 3 H, CH3) ppm.
3-Methoxybiphenyl (4d): Table 2, Entry 4.[16] Purified by flash
chromatography on silica gel (petroleum ether) to give a colorless
oil (78 mg, 85%). 1H NMR (400 MHz, CDCl3): δ = 7.65 (d, J =
7.3 Hz, 2 H, Ar), 7.49 (t, J = 7.3 Hz, 2 H, Ar), 7.41–7.39 (m, 2 H,
Ar), 7.25 (d, J = 8.0 Hz, 1 H, Ar), 7.19 (s, 1 H, Ar), 6.97 (dd, J =
8.2, 2.5 Hz, 1 H, Ar), 3.90 (s, 3 H, CH3) ppm.
General Procedure for Palladium-Catalyzed One-Pot Preparation of
Unsymmetrical Biaryls: A Schlenk tube (10 mL) was charged with
cyclopalladated ferrocenylimine I (8.9 mg, 0.012 mmol) in 1,4-di-
oxane (2.0 mL) followed by the addition of the first aryl halide a
(0.60 mmol), KOAc (118 mg, 1.2 mmol), and bis(pinacolato)dibo-
rane (182 mg, 0.72 mmol). The reaction mixture under nitrogen
was heated to reflux for 2 or 6 h. After the mixture had been cooled
to room temperature, the second aryl halide b (0.50 mmol) in 1,4-
dioxane (0.50 mL) and base (5 m aqueous solution, 0.50 mL) were
added to the reaction mixture under nitrogen. The reaction mixture
was heated to reflux for another 3 or 15 h, cooled to room tempera-
ture, and then diluted with diethyl ether. The mixture was washed
with water (1ϫ), and the organic layer was dried with Na2SO4.
The solvent was removed under reduced pressure, and the crude
material was purified by flash chromatography on silica gel (ethyl
acetate/petroleum ether).
2-Nitrobiphenyl (5d): Table 2, Entry 5.[17] Purified by flash
chromatography on silica gel (petroleum ether) to afford a yellow
1
oil (85 mg, 84%). H NMR (400 MHz, CDCl3): δ = 7.86 (dd, J =
7.6, 0.6 Hz, 1 H, Ar), 7.61 (ddd, J = 7.6, 7.6, 1.3 Hz, 1 H, Ar),
7.48–7.35 (m, 5 H, Ar), 7.35–7.33 (m, 2 H, Ar) ppm.
Biphenyl-2-carbonitrile (6d): Table 2, Entry 6.[18] Purified by flash
chromatography on silica gel (petroleum ether) to afford a colorless
1
oil (74 mg, 82%). H NMR (400 MHz, CDCl3): δ = 7.78 (dd, J =
7.7, 1.2 Hz, 1 H, Ar), 7.56–7.54 (m, 1 H, Ar), 7.50–7.47 (m, 2 H,
Ar), 7.46–7.41 (m, 5 H, Ar) ppm.
4-Nitrobiphenyl (7d): Table 2, Entry 8.[19] Purified by flash
chromatography on silica gel (petroleum ether) to afford a yellow
solid (87 mg, 87%), m.p. 109–110 °C. 1H NMR (400 MHz,
CDCl3): δ = 8.30 (dd, J = 6.6, 1.6 Hz, 2 H, Ar), 7.74 (dd, J = 8.8,
1.9 Hz, 2 H, Ar), 7.63 (dd, J = 7.0, 1.5 Hz, 2 H, Ar), 7.50–7.48 (m,
2 H, Ar), 7.46–7.44 (m, 1 H, Ar) ppm.
1-(Biphenyl-4-yl)ethanone (1d): Table 2, Entry 1.[13] Purified by
flash chromatography on silica gel (ethyl acetate/petroleum ether,
1:20) to afford a white solid (90 mg, 92%), m.p. 116–117 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.04–8.02 (m, 2 H, Ar), 7.70–7.68
(m, 2 H, Ar), 7.64–7.62 (m, 2 H, Ar), 7.49–7.45 (m, 2 H, Ar), 7.42–
7.40 (m, 1 H, Ar), 2.64 (s, 3 H, CH3) ppm.
4-Methylbiphenyl (8d): Table 2, Entry 9.[20] Purified by flash
4-Methoxybiphenyl (2d): Table 2, Entry 2.[14] Purified by flash
chromatography on silica gel (petroleum ether) to afford a colorless
1
chromatography on silica gel (petroleum ether) to afford a white
solid (64 mg, 76%), m.p. 42–43 °C. H NMR (400 MHz, CDCl3):
1
solid (79 mg, 86%), m.p. 83–84 °C. H NMR (400 MHz, CDCl3):
δ = 7.57 (dd, J = 8.4, 1.3 Hz, 2 H, Ar), 7.49 (d, J = 8.1 Hz, 2 H,
600
www.eurjoc.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2012, 595–603

Biaryls through a Borylation/Suzuki–Miyaura Cross-Coupling
Ar), 7.42 (t, J = 7.4 Hz, 2 H, Ar), 7.33–7.31 (m, 1 H, Ar), 7.24 (m,
2 H, Ar), 2.39 (s, 3 H, CH3) ppm.
111.5, 103.8, 29.2 ppm. HRMS (ESI): calcd. for C12H13N2 [M +
H]+ 185.1079; found 185.1081.
2-Chloro-4-phenylpyridine (17d): Table 3, Entry 8.[27] Purified by
flash chromatography on silica gel (ethyl acetate/petroleum ether,
1:5) to afford a white solid (73 mg, 77%), m.p. 58–59 °C. 1H NMR
(400 MHz, CDCl3): δ = 8.43 (d, J = 5.2 Hz, 1 H, pyridine-H), 7.61
(dd, J = 8.1, 1.9 Hz, 2 H, Ar), 7.54 (s, 1 H, pyridine-H), 7.50–7.48
(m, 3 H, Ar), 7.42 (m, 1 H, pyridine-H) ppm.
Biphenyl-3-amine (9d): Table 2, Entry 10.[21] Purified by flash
chromatography on silica gel (ethyl acetate/petroleum ether, 1:7) to
1
afford a colorless oil (80 mg, 95%). H NMR (400 MHz, CDCl3):
δ = 7.55 (d, J = 8.4 Hz, 2 H, Ar), 7.41 (t, J = 7.8 Hz, 2 H, Ar),
7.33 (d, J = 7.2 Hz, 1 H, Ar), 7.24–7.20 (m, 1 H), 6.98 (d, J =
7.6 Hz, 1 H, Ar), 6.66 (s, 1 H, Ar), 6.58 (dd, J = 7.8, 2.1 Hz, 1 H,
Ar), 3.63 (br., 2 H, NH2) ppm.
4-Phenyl-2-pyridinecarbonitrile (18d): Table 3, Entry 9. Purified by
3-Phenylpyridine (10d): Table 3, Entry 11.[13] Purified by flash
flash chromatography on silica gel (ethyl acetate/petroleum ether,
1
1:5) to afford a pale yellow solid (72 mg, 80%), m.p. 92–93 °C. H
chromatography on silica gel (ethyl acetate/petroleum ether, 1:5) to
1
NMR (400 MHz, CDCl3): δ = 8.75 (d, J = 4.9 Hz, 1 H, pyridine-
H), 7.91 (s, 1 H, pyridine-H), 7.72 (dd, J = 5.2, 1.8 Hz, 1 H, pyr-
afford a colorless oil (66 mg, 85%). H NMR (400 MHz, CDCl3):
δ = 8.84 (s, 1 H, pyridine-H), 7.58 (d, J = 3.7 Hz, 1 H, pyridine-
H), 7.85 (d, J = 7.8 Hz, 1 H, pyridine-H), 7.57 (d, J = 7.3 Hz, 2
H, Ar), 7.46 (t, J = 7.2 Hz, 2 H, Ar), 7.39 (d, J = 7.2 Hz, 1 H,
pyridine-H), 7.35 (m, 1 H) ppm.
idine-H), 7.64–7.62 (m, 2 H, Ar), 7.54–7.52 (m, 3 H, Ar) ppm. 13
C
NMR (100 MHz, CDCl3): δ = 148.8, 147.2, 133.3, 131.9, 127.6,
124.4, 123.8, 122.0, 114.7 ppm. HRMS (ESI): calcd. for C12H13N2
[M + H]+ 181.0766; found 181.0764.
2,6-Diphenylpyrazine (19d): Table 3, Entry 10.[28] Purified by flash
chromatography on silica gel (ethyl acetate/petroleum ether, 1:10)
to afford a white solid (108 mg, 93%), m.p. 85–86 °C. 1H NMR
(400 MHz, CDCl3): δ = 8.89 (s, 2 H, pyrazine-H), 8.07 (d, J =
3.4 Hz, 4 H, Ar), 7.48–7.41 (m, 6 H, Ar) ppm.
N,N-Dimethyl-5-phenylpyridin-2-amine (11d): Table 3, Entry 12.[22]
Purified by flash chromatography on silica gel (ethyl acetate/petro-
leum ether, 1:20) to afford a white solid (92 mg, 92%), m.p. 65–
1
66 °C. H NMR (400 MHz, CDCl3): δ = 8.44 (d, J = 2.2 Hz, 1 H,
pyridine-H), 7.70 (dd, J = 8.8, 2.4 Hz, 1 H, pyridine-H), 7.51 (d, J
= 7.4 Hz, 2 H, Ar), 7.40 (t, J = 7.4 Hz, 2 H, Ar), 7.30–7.25 (m, 1
H, Ar), 6.58 (d, J = 8.8 Hz, 1 H, pyridine-H), 3.13 (s, 6 H, NMe2)
ppm.
N,N-Dimethyl-3,3Ј-bipyridin-6-amine (20d): Table 4, Entry 1. Puri-
fied by flash chromatography on silica gel (ethyl acetate/petroleum
1
ether, 1:2) to afford a white solid (74 mg, 74%), m.p. 74–75 °C. H
5-Phenyl-2-pyridinamine (12d): Table 3, Entry 13.[23] Purified by
flash chromatography on silica gel (ethyl acetate/petroleum ether,
1:1) to afford a white solid (83 mg, 98%), m.p. 128–129 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.32 (d, J = 2.1 Hz, 1 H, pyridine-
H), 7.67 (dd, J = 8.5, 2.4 Hz, 1 H, pyridine-H), 7.51–7.49 (m, 2 H,
Ar), 7.44–7.40 (m, 2 H, Ar), 7.33–7.31 (m, 1 H, Ar), 6.58 (d, J =
8.3 Hz, 1 H, pyridine-H), 4.08 (br., 2 H, NH2) ppm.
NMR (400 MHz, CDCl3): δ = 8.78 (s, 1 H, pyridine1-H), 8.53 (d,
J = 3.9 Hz, pyridine1-H), 8.42 (s, 1 H, pyridine2-H), 7.81–7.78 (m,
1 H, pyridine1-H), 7.68 (dd, J = 8.8, 2.5 Hz, 1 H, pyridine1-H),
7.33 (dd, J = 7.8, 4.7 Hz, 1 H, pyridine2-H), 6.61 (d, J = 8.8 Hz, 1
H, pyridine2-H), 3.14 (s, 6 H, CH3) ppm. 13C NMR (100 MHz,
CDCl3): δ = 158.7, 147.3, 147.0, 145.9, 135.4, 134.1, 132.9, 123.4,
120.6, 105.7, 37.9 ppm. HRMS (ESI): calcd. for C12H14N3 [M +
H]+ 200.1188; found 200.1188.
2-Methyl-5-phenylpyridine (13d): Table 3, Entry 4.[24] Purified by
flash chromatography on silica gel (ethyl acetate/petroleum ether,
2-Methyl-3,3Ј-bipyridine (21d): Table 4, Entry 2. Purified by flash
1
1:20) to afford a colorless oil (69 mg, 81%). H NMR (400 MHz,
chromatography on silica gel (ethyl acetate/petroleum ether, 1:1) to
CDCl3): δ = 8.74 (d, J = 2.2 Hz, 1 H, pyridine-H), 7.78 (dd, J =
8.0, 2.4 Hz, 1 H, pyridine-H), 7.58–7.56 (m, 2 H, Ar), 7.47 (t, J =
7.8 Hz, 2 H, Ar), 7.41–7.39 (m, 1 H, Ar), 7.23 (d, J = 8.0 Hz,
pyridine-H), 2.61 (s, 3 H, CH3) ppm.
1
afford a colorless oil (69 mg, 81%). H NMR (400 MHz, CDCl3):
δ = 8.65 (d, J = 7.2 Hz, 1 H, pyridine2-H), 8.60 (s, 1 H, pyridine
1-H), 8.55 (dd, J = 4.8, 1.3 Hz, 1 H, pyridine1-H), 6.67 (d, J =
7.8 Hz, pyridine1-H), 7.41 (d, J = 4.9 Hz, 1 H, pyridine2-H), 7.24
(dd, J = 7.8, 4.8 Hz, 1 H, pyridine1-H), 2.52 (s, 3 H, CH3) ppm.
13C NMR (100 MHz, CDCl3): δ = 155.9, 149.6, 148.7, 148.7, 137.2,
136.3, 135.5, 133.2, 123.2, 121.2, 23.2 ppm. HRMS (ESI): calcd.
for C11H11N2 [M + H]+ 171.0922; found 171.0919.
2-Methyl-3-phenylpyridine (14d): Table 3, Entry 5.[25] Purified by
flash chromatography on silica gel (ethyl acetate/petroleum ether,
1:5) to afford a colorless oil (70 mg, 83%). 1H NMR (400 MHz,
CDCl3): δ = 8.49 (dd, J = 4.8, 1.6 Hz, pyridine-H), 7.50 (dd, J =
7.6, 1.6 Hz, 1 H, pyridine-H), 7.44–7.41 (m, 2 H, Ar), 7.37 (d, J =
7.2 Hz, pyridine-H), 7.30 (d, J = 8.3 Hz, Ar), 7.18–7.16 (m, 1 H,
Ar), 2.50 (s, 3 H, CH3) ppm.
4-Methyl-3,3Ј-bipyridine (22d): Table 4, Entry 3. Purified by flash
chromatography on silica gel (ethyl acetate/petroleum ether, 3:1) to
1
afford a colorless oil (70 mg, 82%). H NMR (400 MHz, CDCl3):
4-Methyl-3-phenylpyridine (15d): Table 3, Entry 6.[26] Purified by
δ = 8.65 (d, J = 4.8 Hz, 1 H, pyridine1-H), 8.60 (s, 1 H, pyridine1-
H), 8.50 (d, J = 4.8 Hz, 1 H, pyridine2-H), 8.43 (s, 1 H, pyridine2-
H), 7.69–7.66 (m, 1 H, pyridine1-H), 7.43–7.40 (m, 1 H, pyridine1-
H), 7.24 (d, J = 4.8 Hz, 1 H, pyridine2-H), 2.30 (s, 3 H, CH3) ppm.
13C NMR (100 MHz, CDCl3): δ = 149.7, 149.0, 148.8, 144.8, 136.5,
134.0, 133.5, 125.3, 123.2, 19.6 ppm. HRMS (ESI): calcd. for
C11H11N2 [M + H]+ 171.0922; found 171.0923.
flash chromatography on silica gel (ethyl acetate/petroleum ether,
1
1:10) to afford a colorless oil (61 mg, 72%). H NMR (400 MHz,
CDCl3): δ = 8.44 (d, J = 4.5 Hz, 1 H, pyridine-H), 8.43 (s, 1 H,
pyridine-H), 7.46–7.44 (m, 2 H, Ar), 7.43 (d, J = 6.3 Hz, 1 H, Ar),
7.32–7.30 (m, 2 H, Ar), 7.18 (d, J = 4.9 Hz, 1 H, pyridine-H), 2.28
(s, 3 H, CH3) ppm.
N-Methyl-4-phenylpyridin-2-amine (16d): Table 3, Entry 7. Purified
by flash chromatography on silica gel (ethyl acetate/petroleum
ether, 2:1) to afford a white solid (82 mg, 89%), m.p. 106–107 °C.
1H NMR (400 MHz, CDCl3): δ = 8.14 (d, J = 5.3 Hz, 1 H, pyr-
idine-H), 7.61–7.55 (m, 2 H, Ar), 7.59–7.40 (m, 3 H, Ar), 6.81 (dd,
J = 5.3, 1.4 Hz, 1 H, pyridine-H), 6.56 (s, 1 H, pyridine-H), 4.64
N-Methyl-3,4Ј-bipyridin-2Ј-amine (23d): Table 4, Entry 4. Purified
by flash chromatography on silica gel (ethyl acetate/petroleum
1
ether, 1:1) to afford a white solid (83 mg, 90%), m.p. 70–71 °C. H
NMR (400 MHz, CDCl3): δ = 8.85 (s, 1 H, pyridine1-H), 8.64 (d,
J = 4.7 Hz, 1 H, pyridine1-H), 8.17 (d, J = 5.1 Hz, 1 H, pyridine2-
H), 7.88 (dd, J = 7.8, 5.1 Hz, 1 H, pyridine1-H), 7.39–7.37 (m, 1
(br., 1 H, NH), 2.98 (d, J = 4.6 Hz, 3 H, CH3) ppm. 13C NMR H, pyridine1-H), 6.77 (d, J = 5.1 Hz, 1 H, pyridine-H), 6.54 (s, 1
(100 MHz, CDCl3): δ = 160.1, 149.9, 148.5, 139.2, 128.8, 126.9, H, pyridine2-H), 4.98 (br., 1 H, NH), 2.98 (d, J = 4.8 Hz, CH3)
Eur. J. Org. Chem. 2012, 595–603
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
601

L. Wang, X. Cui, J. Li, Y. Wu, Z. Zhu, Y. Wu
FULL PAPER
ppm. 13C NMR (100 MHz, CDCl3): δ = 161.6, 151.0, 150.3, 149.4,
148.1, 136.3, 135.7, 125.0, 112.4, 105.1, 30.5 ppm. HRMS (ESI):
calcd. for C11H12N3 [M + H]+ 186.1031; found 186.1034.
δ = 164.9, 163.7, 151.7, 148.9, 147.1, 139.2, 114.3, 113.4, 111.3,
108.0, 53.5, 53.2 ppm. HRMS (ESI): calcd. for C12H13N2O2 [M +
H]+ 217.0977; found 217.0976.
4-Methoxy-4Ј-(trifluoromethyl)biphenyl (30d): Table 5, Entry 2.[29]
Purified by flash chromatography on silica gel (petroleum ether) to
afford a white solid (120 mg, 95%), m.p. 118–119 °C. 1H NMR
(400 MHz, CDCl3): δ = 7.70–7.66 (m, 4 H, Ar), 7.57 (dd, J = 6.6,
2.1 Hz, 2 H, Ar), 7.03 (dd, J = 6.6, 2.1 Hz, Ar), 3.89 (s, 3 H, CH3)
ppm.
2Ј-Methylbiphenyl-2-carbonitrile (31d): Table 5, Entry 4.[30] Purified
by flash chromatography on silica gel (ethyl acetate/petroleum
ether, 1:30) to afford a white solid (90 mg, 91%), m.p. 35–36 °C.
1H NMR (400 MHz, CDCl3): δ = 7.57–7.55 (m, 4 H, Ar), 7.47–
7.45 (m, 2 H, Ar), 6.93–6.91 (m, 2 H, Ar) ppm.
2Ј-Chloro-3,4Ј-bipyridine (24d): Table 4, Entry 5. Purified by flash
chromatography on silica gel (ethyl acetate/petroleum ether, 1:2)
1
to afford a white solid (74 mg, 78%), m.p. 105–106 °C. H NMR
(400 MHz, CDCl3): δ = 8.88 (s, pyridine1-H), 8.72 (dd, J = 4.8,
1.4 Hz, 1 H, pyridine2-H), 8.49 (d, J = 5.5 Hz, 1 H, pyridine2-H),
7.91 (d, J = 7.8 Hz, 1 H, pyridine1-H), 7.55 (s, 1 H, pyridine2-
H), 7.45–7.43 (m, 2 H, pyridine1-H, pyridine2-H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 152.4, 150.7, 150.3, 148.3, 148.0, 134.3,
132.6, 123.8, 122.0, 120.3 ppm. HRMS (ESI): calcd. for C10H8ClN2
[M + H]+ 191.0376; found 191.0374.
2Ј-Methoxy-3,4Ј-bipyridine (25d): Table 4, Entry 6. Purified by flash
chromatography on silica gel (ethyl acetate/petroleum ether, 1:3) to
afford a white solid (86 mg, 92%), m.p. 30–31 °C. 1H NMR
(400 MHz, CDCl3): δ = 8.83 (s, 1 H, pyridine1-H), 8.64 (d, J =
4.0 Hz, 1 H, pyridine1-H), 8.23 (d, J = 5.2 Hz, 1 H, pyridine1-H),
7.87 (d, J = 7.8 Hz, 1 H, pyridine2-H), 7.40–7.36 (m, 1 H, pyr-
idine1-H), 7.07 (dd, J = 5.2, 0.7 Hz, 1 H, pyridine2-H), 6.92 (s, 1
H, pyridine2-H), 3.96 (s, 3 H, CH3) ppm. 13C NMR (100 MHz,
CDCl3): δ = 164.8, 149.8, 147.9, 147.7, 147.5, 134.2, 133.8, 123.6,
114.9, 108.5, 53.5 ppm. HRMS (ESI): calcd for C11H11N2O [M +
H]+ 187.0871; found 187.0873.
Supporting Information (see footnote on the first page of this arti-
1
cle): H and 13C NMR spectra of the products.
Acknowledgments
We are grateful to the National Natural Science Foundation of
China (NSFC) (20972139) and the National Science Foundation
(NSF) of Henan (082300423201) for their financial support of this
research.
3,4Ј-Bipyridine-2Ј-carbonitrile (26d): Table 4, Entry 7. Purified by
flash chromatography on silica gel (ethyl acetate/petroleum ether,
1:1) to afford a white solid (78 mg, 86%), m.p. 177–178 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.91 (s, 1 H, pyridine1-H), 8.82 (d,
J = 4.8 Hz, 1 H, pyridine2-H), 7.77 (dd, J = 4.8, 1.5 Hz, 1 H,
pyridine2-H), 7.93–9.72 (m, 2 H, pyridine1-H, pyridine2-H), 7.74
(dd, J = 5.2, 1.8 Hz, 1 H, pyridine1-H), 7.51–7.49 (m, 1 H, pyr-
idine1-H) ppm. 13C NMR (100 MHz, CDCl3): δ = 153.2, 152.6,
149.4, 148.2, 136.3, 135.7, 133.2, 127.4, 125.9, 125.5, 118.4 ppm.
HRMS (ESI): calcd. for C11H8N3 [M + H]+ 182.0718; found
182.0719.
[1] a) N. T. S. Phan, M. Van Der Sluys, C. W. Jones, Adv. Synth.
Catal. 2006, 348, 609–679; b) S. L. Buchwald, D. S. Surry, An-
gew. Chem. 2008, 120, 6438–6461; Angew. Chem. Int. Ed. 2008,
47, 6338–6361; c) I. A. I. Mkhalid, J. H. Barnard, T. B. Marder,
J. M. Murphy, J. F. Hartwig, Chem. Rev. 2010, 110, 890–931.
[2] a) N. Miyaura, A. Suzuki, Chem. Rev. 1995, 95, 2457–2483; b)
J. Ma, X. L. Cui, B. Zhang, M. P. Song, Y. J. Wu, Tetrahedron
2007, 63, 5529–5538; c) A. F. Littke, G. C. Fu, Angew. Chem.
2002, 114, 4350–4386; Angew. Chem. Int. Ed. 2002, 41, 4176–
4211; d) D. Alberico, M. E. Scott, M. Lautens, Chem. Rev.
2007, 107, 174–238.
[3] T. Ishiyama, Y. Itoh, T. Kitano, N. Miyaura, Tetrahedron Lett.
1997, 38, 3447–3450.
2,3Ј-Bipyridine (27d): Table 4, Entry 8.[20] Purified by flash
[4] a) A. Kondoh, T. F. Jamison, Chem. Commun. 2010, 46, 907–
909; b) T. E. Hurst, T. K. Macklin, M. Becker, E. Hartmann,
W. Kügel, J.-C. Parisienne-La Salle, A. S. Batsanov, T. B.
Marder, V. Snieckus, Chem. Eur. J. 2010, 16, 8155–8161; c) M.
Klecˇka, R. Pohl, B. Klepetárˇová, M. Hocek, Org. Biomol.
Chem. 2009, 7, 866–868; d) P. Harrisson, J. Morris, T. B.
Marder, P. G. Steel, Org. Lett. 2009, 11, 3586–3589; e) P. Har-
risson, J. Morris, P. G. Steel, T. B. Marder, Synlett 2009, 147–
150; f) V. J. Olsson, K. J. Szabó, Org. Lett. 2008, 10, 3129–3131;
g) A. D. Finke, J. S. Moore, Org. Lett. 2008, 10, 4851–4854.
[5] a) N. PraveenGanesh, P. Y. Chavant, Eur. J. Org. Chem. 2008,
4690–4696; b) L. Zhu, M. Patel, M. Zhang, Tetrahedron Lett.
2008, 49, 2734–2737; c) O. Baudoin, M. Cesario, D. Guénard,
F. Guéritte, J. Org. Chem. 2002, 67, 1199–1207; d) O. Baudoin,
D. Gunard, F. Guritte, J. Org. Chem. 2000, 65, 9268–9271.
[6] a) M. Deodhar, D. StC. Black, D. S.-H. Chan, N. Kumar, Het-
erocycles 2010, 80, 1267–1274; b) T. Martin, C. Laguerre, C.
Hoarau, F. Marsais, Org. Lett. 2009, 11, 3690–3693; c) H. A.
Duong, S. Chua, P. B. Huleatt, C. L. L. Chai, J. Org. Chem.
2008, 73, 9177–9180; d) E. F. DiMauro, J. R. Vitullo, J. Org.
chromatography on silica gel (ethyl acetate/petroleum ether, 1:3) to
afford a colorless oil (57 mg, 73%). H NMR (400 MHz, CDCl3):
δ = 9.19 (s, 1 H, pyridine1-H), 8.73 (d, J = 4.8 Hz, 1 H, pyridine1-
H), 8.64 (d, J = 4.7 Hz, 1 H, pyridine1-H), 8.32 (d, J = 7.8 Hz, 1
H, pyridine2-H), 7.80–7.76 (m, 2 H, pyridine1-H, pyridine2-H),
7.41 (m, 1 H, pyridine2-H), 7.30–7.28 (m, 1 H, pyridine2-H) ppm.
1
2Ј-Methoxy-N-methyl-4,4Ј-bipyridin-2-amine (28d): Table 4, En-
try 9. Purified by flash chromatography on silica gel (ethyl acetate/
petroleum ether, 1:3) to afford a white solid (98 mg, 91%), m.p. 70–
1
71 °C. H NMR (400 MHz, CDCl3): δ = 8.24 (d, J = 5.3 Hz, 1 H,
pyridine2-H), 8.18 (d, J = 5.3 Hz, 1 H, pyridine2-H), 7.08 (dd, J =
5.3, 1.2 Hz, 1 H, pyridine1-H), 6.95 (s, 1 H, pyridine2-H), 6.78 (dd,
J = 5.2, 1.2 Hz, 1 H, pyridine1-H), 6.55 (s, 1 H, pyridine1-H), 4.78
(br., 1 H, NH), 3.99 (s, 3 H, CH3), 2.98 (d, J = 5.0 Hz, 3 H, NCH3)
ppm. 13C NMR (100 MHz, CDCl3): δ = 163.8, 159.1, 148.5, 147.9,
146.4, 146.2, 113.9, 109.9, 107.5, 102.6, 52.5, 28.1 ppm. HRMS
(ESI): calcd. for C12H14N3O [M + H]+ 216.1137; found 216.1137.
ˇ
Chem. 2006, 71, 3959–396; e) P.-E. Broutin, I. Cernˇa, M. Cam-
2Ј,6-Dimethoxy-2,4Ј-bipyridine (29d): Table 4, Entry 10. Purified by
flash chromatography on silica gel (ethyl acetate/petroleum ether,
1:10) to afford a white solid (84 mg, 78%), m.p. 56–57 °C. 1H NMR
(400 MHz, CDCl3): δ = 8.17 (d, J = 5.4 Hz, 1 H, pyridine1-H),
7.58 (t, J = 8.2 Hz, 1 H, pyridine2-H), 7.42 (d, J = 5.4 Hz, 1 H,
pyridine1-H), 7.34 (s, 1 H, pyridine1-H), 7.30 (d, J = 7.4 Hz, 1 H,
pyridine2-H), 6.70 (d, J = 8.2 Hz, 1 H, pyridine2-H), 3.95 (s, 3 H,
OCH3), 3.92 (s, 3 H, OCH3) ppm. 13C NMR (100 MHz, CDCl3):
paniello, F. Leroux, F. Colobert, Org. Lett. 2004, 6, 4419–4422;
f) I. C. F. R. Ferreira, M.-J. R. P. Queiroz, G. Kirsch, Tetrahe-
dron Lett. 2003, 44, 4327–4329; g) A. S. Abreu, N. O. Silva,
P. M. T. Ferreira, M.-J. R. P. Queiroz, Tetrahedron Lett. 2003,
44, 6007–6009; h) L. Zhu, J. Duquette, M. Zhang, J. Org.
Chem. 2003, 68, 3729–3732.
[7] a) M. Miura, T. Koike, T. Ishihara, F. Hirayama, S. Sakamoto,
M. Okada, M. Ohta, S. Tsukamoto, Synth. Commun. 2006, 36,
602
www.eurjoc.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2012, 595–603

Biaryls through a Borylation/Suzuki–Miyaura Cross-Coupling
3809–3820; b) M. Penhoat, V. Levacher, G. Dupas, J. Org.
Chem. 2003, 68, 9517–9520.
[15] W. J. Zhou, K. H. Wang, J. X. Wang, J. Org. Chem. 2009, 74,
5599–5602.
[16] K. C. Y. Lau, H. S. He, P. Chiu, P. H. Toy, J. Comb. Chem.
2004, 6, 955–960.
[17] L. Caron, L. C. Campeau, K. Fagnou, Org. Lett. 2008, 10,
4533–4536.
[18] Q. Yang, S. M. Ma, J. X. Li, F. S. Xiao, H. Xiong, Chem. Com-
mun. 2006, 2495–2497.
[19] G. R. Rosa, C. H. Rosa, F. Rominger, J. Dupont, A. L. Mon-
teiro, Inorg. Chim. Acta 2006, 359, 1947–1954.
[20] P. D. Stevens, J. Fan, H. M. R. Gardimalla, M. Yen, Y. Gao,
Org. Lett. 2005, 7, 2085–2088.
[21] B. Tao, D. W. Boykin, J. Org. Chem. 2004, 69, 4330–4335.
[22] L. H. Heitman, J. P. D. van Veldhoven, A. M. Zweemer, K. Ye,
J. Brussee, A. P. IJzerman, J. Med. Chem. 2008, 51, 4724–4729.
[23] T. Itoh, T. Mase, Tetrahedron Lett. 2005, 46, 3573–3577.
[24] B. W. Xin, J. Chem. Res. (S) 2008, 7, 412–415.
[25] D. Craig, F. Paina, S. C. Smith, Chem. Commun. 2008, 3408–
3410.
[26] P. T. F. McLoughlin, M. A. Clyne, F. Aldabbagh, Tetrahedron
2004, 60, 8065–8071.
[27] J. J. Hangeland, M. L. Quan, J. M. Smallheer, G. S. Bisacchi,
J. R. Corte, T. J. Friends, Z. Sun, K. A. Rossi, C. L. Cavallaro,
US Patent 7429604B2.20080930, 2008.
[8]
a) G. Uray, A.-M. Kelterer, J. Hashim, T. N. Glasnov, C. O.
Kappe, W. M. F. Fabian, J. Mol. Struct. 2009, 929, 85–96; b)
M.-J. R. P. Queiroz, E. M. S. Castanheira, T. C. T. Lopes, Y. K.
Cruz, G. Kirsch, J. Photochem. Photobiol., A 2007, 190, 45–52;
c) E. F. DiMauro, J. R. Vitullo, J. Org. Chem. 2006, 71, 3959–
3962; d) A. S. Abreu, P. M. T. Ferreira, M.-J. R. P. Queiroz,
I. C. F. R. Ferreira, R. C. Calhelha, L. M. Estevinho, Eur. J.
Org. Chem. 2005, 2951–2957; e) M. Melucci, G. Barbarella, M.
Zambianchi, P. D. Pietro, A. Bongini, J. Org. Chem. 2004, 69,
4821–4828; f) O. Skaff, K. A. Jolliffe, C. A. Hutton, J. Org.
Chem. 2005, 70, 7353–7363; g) G. W. Kabalka, M.-L. Yao, Tet-
rahedron Lett. 2003, 44, 7885–7887.
K. L. Billingsley, T. E. Barder, S. L. Buchwald, Angew. Chem.
2007, 119, 5455–5459; Angew. Chem. Int. Ed. 2007, 46, 5359–
5363.
a) L. H. Wang, J. Y. Li, X. L. Cui, Y. S. Wu, Z. W. Zhu, Y. J.
Wu, Adv. Synth. Catal. 2010, 352, 2002–2010; b) C. Xu, J. F.
Gong, M. P. Song, Y. J. Wu, Transition Met. Chem. 2009, 34,
175–179; c) N. Ma, Z. W. Zhu, Y. J. Wu, Tetrahedron 2007, 63,
4625–4629.
[9]
[10]
[11] S. Q. Huo, Y. J. Wu, C. X. Du, Y. Zhu, H. Z. Yuan, X. A. Mao,
J. Organomet. Chem. 1994, 483, 139–146.
[12] J. F. Gong, G. Y. Liu, C. X. Du, Y. Zhu, Y. J. Wu, J. Organomet.
Chem. 2005, 690, 3963–3969.
[13] E. Alacid, C. Nájera, Org. Lett. 2008, 10, 5011–5014.
[14] I. J. S. Fairlamb, A. R. Kapdi, A. F. Lee, Org. Lett. 2004, 6,
4435–4438.
[28] M. M. Marcial, Synlett 2006, 3001–3004.
[29] L. Ackermann, A. Althammer, Org. Lett. 2006, 8, 3457–3460.
[30] Z. X. Xi, Y. B. Zhou, W. Z. Chen, J. Org. Chem. 2008, 73,
8497–8501.
Received: September 27, 2011
Published Online: November 29, 2011
Eur. J. Org. Chem. 2012, 595–603
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
603