Palladium-catalyzed Suzuki-Miyaura cross-coupling using phosphinous acids and dialkyl(chloro)phosphane ligands

Article abstract of DOI:10.1002/ejoc.200500843

The use of eleven palladium complexes having monomeric and μ-chloro-bridged dimeric structures and either bulky dialkyl- and diarylphosphinous acid ligands (POPd, POPd-Br, POPd1, POPd2, POPd6, POPd7, Ph1-Phoxide) or dialkyl(chloro)phosphane ligands (PXPd, PXPd2, PXPd6, PXPd7) for Suzuki-Miyaura coupling reactions has been evaluated. Screening and optimization of catalyst loading, solvent, temperature, and base showed that excellent results can be obtained with electron-deficient and electron-rich aryl iodides, bromides, and chlorides in the presence of 2.5 mol-% of palladium-phosphinous acid POPd, (tBu₂POH)₂PdCl₂, in 1,4-dioxane using cesium carbonate as base. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Full text of DOI:10.1002/ejoc.200500843

FULL PAPER
DOI: 10.1002/ejoc.200500843
Palladium-Catalyzed Suzuki–Miyaura Cross-Coupling Using Phosphinous
Acids and Dialkyl(chloro)phosphane Ligands
[a]
[a]
Christian Wolf* and Kekeli Ekoue-Kovi
Keywords: Cross-coupling / Palladium / Homogeneous catalysis / Biaryls
The use of eleven palladium complexes having monomeric
and µ-chloro-bridged dimeric structures and either bulky di-
alkyl- and diarylphosphinous acid ligands (POPd, POPd-Br,
POPd1, POPd2, POPd6, POPd7, Ph1-Phoxide) or dialk-
yl(chloro)phosphane ligands (PXPd, PXPd2, PXPd6, PXPd7)
for Suzuki–Miyaura coupling reactions has been evaluated.
Screening and optimization of catalyst loading, solvent, tem-
perature, and base showed that excellent results can be ob-
tained with electron-deficient and electron-rich aryl iodides,
bromides, and chlorides in the presence of 2.5 mol-% of pal-
2 2 2
ladium–phosphinous acid POPd, (tBu POH) PdCl , in 1,4-di-
oxane using cesium carbonate as base.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
Introduction
such as aryl halides and triflates are among the most ef-
ficient carbon–carbon bond-forming reactions. Its wide-
[
6]
Transition-metal-catalyzed cross-coupling reactions of spread popularity stems from distinctive advantages over
aryl halides and boronic acids, organostannanes, organo- other coupling methods. Typical features of Suzuki–Mi-
siloxanes, organozinc, and Grignard reagents have become yaura couplings are mild reaction conditions, facile hand-
laboratory routine during recent years due to the develop- ling and low toxicity of the reagents, commercial availability
ment of readily available palladium complexes which exhi- of numerous boronic acid substrates, and excellent func-
bit high catalytic activity.[ Especially, electron-rich and tional group tolerance. The preparation of complex mole-
bulky phosphane ligands such as 2-(biphenyl)(dicyclohexyl)- cules exhibiting biaryl units is often accomplished through
1]
[
2]
phosphanes and tri-tert-butylphosphane and derivatives Suzuki–Miyaura coupling, which has been applied in the
[
3]
thereof, or sterically demanding N-heterocyclic carbene li- synthesis of many natural products and pharmacologically
[
4]
[7]
[8]
gands have been shown to afford palladium(0) species active compounds, such as losartan, (–)-steganone,
[
9]
[10]
[11]
that easily undergo oxidative addition with aryl halides in- dragmacidin F, eupomatilone-6,
valsartan,
pulvinic
[
12]
[13]
cluding non-activated chlorides thus providing excellent re- acids, and isoneocryptolepine.
sults in the coupling reactions mentioned above. The effi- In continuation of our previous efforts to utilize palla-
cacy of palladium–phosphinous acid complexes POPd, dium–phosphinous acids POPd, POPd1, and POPd2 in C–
POPd1, and POPd2 in cross-couplings including Stille, Hi- C, C–N, and C–S bond formation, we have employed 11
yama, Sonogashira, and Heck reactions using organic sol- palladium complexes bearing either bulky phosphinous acid
vents and water, respectively, has recently been reported by groups (POPd, POPd-Br, POPd1, POPd2, POPd6, POPd7,
[
5]
us and others. General features of palladium–phosphi- Ph1-Phoxide) or dialkyl(chloro)phosphane ligands (PXPd,
nous acid catalysts include simple preparation from readily PXPd2, PXPd6, PXPd7) in Suzuki–Miyaura coupling of
available phosphane oxides, RRЈP(O)H, and Pd (dba) , aryl iodides, bromides, or chlorides and organoboronic ac-
2
3
Pd(cod)Cl or Pd(OAc) , stability to air and water facilita- ids (Figure 1 and Figure 2). The catalysts studied comprise
2
2
ting operation and catalyst recycling, and high catalytic ac- monomeric and µ-chloro-bridged dimeric structures exhib-
tivity. iting phosphane ligands with tert-butyl, cyclohexyl, and
Palladium- and nickel-catalyzed Suzuki–Miyaura coup- phenyl substituents. Similar to all mononuclear complexes,
lings of organoboron compounds and various electrophiles the dinuclear palladium–phosphinous acids POPd1,
POPd7, and Ph1-Phoxide bear two phosphane ligands at
each palladium center, whereas POPd2, POPd6 and their
dialkyl(chloro)phosphane analogs PXPd2 and PXPd6 have
a phosphane ligand/Pd ratio of 1:1.
[
a] Department of Chemistry, Georgetown University,
Washington, DC 20057, USA
E-mail: cw27@georgetown.edu
Eur. J. Org. Chem. 2006, 1917–1925
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1917

C. Wolf, K. Ekoue-Kovi
FULL PAPER
Figure 1. Structures of palladium–phosphinous acids.
Scheme 1. Suzuki–Miyaura cross-coupling of 4-chloro-2-methyl-
quinoline (1) and 3,5-dimethylphenylboronic acid (2).
Table 1. Yields of 4-(3Ј,5Ј-dimethylphenyl)-2-methylquinoline (3)
obtained by Suzuki–Miyaura cross-coupling of 4-chloro-2-methyl-
quinoline (1) and 3,5-dimethylphenylboronic acid (2) with various
Figure 2. Structures of dialkyl(chloro)phosphane-derived palla-
dium catalysts.
[a]
Pd catalysts.
Entry Catalyst
Yield (%)[b][c]
1
2
3
4
5
6
7
8
9
POPd (tBu
POPd1 [(tBu
POPd2 [(tBu
POPd6 [(Cy POH)(µ-Cl)PdCl]
2 2
POPd7 [(Cy POH)(Cy PO)(µ-Cl)Pd]
2
POH)
2
2
PdCl
POH)(tBu
POH)(µ-Cl)PdCl]
2
73
50
42
55
70
70
55
55
52
63
55
Results and Discussion
2 2
PO)(µ-Cl)Pd]
2
2
Based on our previous experience with palladium–phos-
phinous acid catalyzed cross-couplings, we decided to eval-
uate the ability of POPd, POPd-Br, POPd1, POPd2,
POPd6, POPd7, Ph1-Phoxide and their chlorophosphane-
derived analogs PXPd, PXPd2, PXPd6, and PXPd7 to pro-
mote the coupling reaction of 4-chloro-2-methylquinoline
2
2
2
PXPd (tBu
2
2
PCl) PdCl
2
PXPd2 [(tBu
PXPd6 [(Cy
PXPd7 (Cy
POPd-Br (tBu
Ph1-Phoxide [(Ph
2
PCl)(µ-Cl)PdCl]
2
2
PCl)(µ-Cl)PdCl]
2
2
PCl)
2
PdCl
2
10
2
POH)
2
PdBr
2
(1) and 3,5-dimethylphenylboronic acid (2) in acetonitrile
11
2
POH)(Ph
2
PO)(µ-Cl)Pd]
2
in the presence of an inorganic base (Scheme 1). For better
comparison, all reactions were conducted under identical 10 mol-% Pd catalyst, and 1.5 equiv. of Cs CO in 3 mL of ACN
conditions employing 10 mol-% of the catalysts and
[
a] All reactions were carried out with 100 mg of 1, 1.2 equiv. of 2,
2
3
at 82 °C for 20 h. [b] Isolated yields of 4-(3Ј,5Ј-dimethylphenyl)-2-
methylquinoline (3). [c] No product was obtained in the absence of
Cs CO .
2 3
1
2
.5 equiv. of cesium carbonate in acetonitrile at 82 °C for
0 h. Our initial screening showed that all Pd complexes
catalyze the formation of 4-(3Ј,5Ј-dimethylphenyl)-2-meth-
ylquinoline (3), albeit in varying yields, Table 1.
highest catalytic activity providing 3 in 70 to 73% (Entries
The dimeric complexes POPd2, POPd6, PXPd2, and 1, 5, and 6). The comparison of the yields of 3 obtained
PXPd6 which exhibit a palladium/phosphane ligand ratio with dinuclear catalysts exhibiting two phosphinous acid li-
of 1:1 proved to give only moderate yields, i.e. 42–55% gands attached to each palladium center (POPd1, POPd7,
(Table 1, Entries 3, 4, 7, and 8). Representing mono- and and Ph1-Phoxide) reveals that the incorporation of cyclo-
dinuclear structures having either two dialkylphosphinous hexyl groups into the phosphane ligands affords superior
acid or two dialkyl(chloro)phosphane ligands attached to results (Entries 2, 5, and 11). By contrast, the replacement
one palladium atom, POPd, POPd7, and PXPd showed the of cyclohexyl groups of monomeric palladium–dialkyl-
1918
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Eur. J. Org. Chem. 2006, 1917–1925

Pd-Catalyzed Suzuki–Miyaura Cross-Coupling Reactions
FULL PAPER
(chloro)phosphanes by bulky tert-butyl groups increased
Although excellent results were also observed in ethyl
the yields of 3 from 52 to 70% (Entries 6 and 9). Results acetate at 80 °C (Table 2, Entry 4) we decided to continue
obtained with POPd and POPd-Br showed that the replace- our optimization efforts evaluating the effect of base with
ment of chloro ligands attached to the palladium center by PXPd in 1,4-dioxane, Table 3. Screening of tBuOK,
bromide reduces the catalytic activity by 10% (Entries 1 Cy NMe, and various inorganic bases showed that cesium
2
and 10). All reactions gave the biaryl 3 and recovered start- carbonate affords superior results while high yields of the
ing materials but no side-products after work-up suggesting cross-coupling product 3 can also be obtained in the pres-
that cross-coupling results can be further improved by opti- ence of potassium carbonate and potassium phosphate (En-
mization of the reaction conditions, such as solvent, tem- tries 2, 5, and 8). Variation of PXPd loading using Cs CO3
2
perature, and base.
as base in 1,4-dioxane proved that the catalyst amount can
We then screened the most promising catalysts POPd, be reduced to 2.5 mol-% without compromising yields
POPd7, and PXPd in various solvents reducing the catalyst (compare Entries 8–11).
loading to 5 mol-% to further optimize the reaction condi-
tions and to better differentiate between the activity of these Table 3. Screening of the PXPd-catalyzed Suzuki–Miyaura forma-
tion of 3 in the presence of different bases and optimization of
Pd complexes (Table 2). Employing POPd in refluxing
THF, toluene, 2-propanol, ethyl acetate, dimethylform-
catalyst loading.[
a]
Entry
Base
Catalyst loading [mol-%] Yield [%][b]
amide, and 1,4-dioxane showed that the latter gives superior
results, which may be attributed to the enhanced solubility
of cesium carbonate in this solvent (Entries 1–7). Under
these conditions, monomeric POPd and PXPd exhibiting
di-tert-butylphosphinous acid and di-tert-butyl(chloro)-
phosphane ligands gave 3 in 93 and 86% yield while dimeric
POPd7 bearing dicyclohexylphosphinous acids provided
the coupling product in only 72% (Entries 7–9).
1
2
3
4
5
6
7
8
9
tBuOK
5
5
5
5
5
5
5
5
63
80
66
66
77
18
30
86
86
88
66
K
3
PO
4
NaOAc
NaOH
K
Na
Cy
2
CO
3
2
CO
3
2
NMe
Cs
Cs
Cs
2
CO
CO
CO
3
3
3
3
2
2
10
2.5
1.0
10
Table 2. Formation of 4-(3Ј,5Ј-dimethylphenyl)-2-methylquinoline
11
2
Cs CO
[
a]
(3) using POPd, PXPd, and PXPd7 in different solvents.
[
a] All reactions were carried out with 100 mg of 1, 1.1 equiv. of 2,
Entry Catalyst
Solvent
T (°C)
Yield[b] (%)
and 1.5 equiv. of base in 3 mL of 1,4-dioxane at 100 °C for 20 h.
[b] Isolated yields.
1
2
3
4
5
6
7
8
9
POPd
POPd
POPd
POPd
POPd
POPd
POPd
PXPd
POPd7
THF
66
110
82
80
145
82
25
66
50
86
75
73
93
86
72
toluene
2-propanol
EtOAc
DMF
Having optimized the catalyst choice, solvent, base, and
catalyst loading, using quinolyl chloride 1 and boronic acid
, we employed a variety of aryl chlorides in the POPd-
catalyzed Suzuki–Miyaura cross-coupling reactions using
.5 equiv. of Cs CO and 2.5 mol-% of the catalyst in 1,4-
2
ACN
1,4-dioxane 100
1,4-dioxane 100
1,4-dioxane 100
1
2
3
dioxane, Table 4. We were pleased to find that coupling of
and arylboronic acids 2, 4, and 6 affords the correspond-
1
[
1
a] All reactions were carried out with 100 mg of aryl chloride 1,
.1 equiv. of boronic acid 2, 5 mol-% Pd catalyst, and 1.5 equiv. of
Cs CO in 3 mL solvent for 20 h. [b] Isolated yields.
ing 4-aryl-2-methylquinolines 3, 5, and 7 in 93 to 98% (En-
tries 1–3). The formation of trans-alkene 9 from 1 and vinyl-
2
3
Table 4. POPd-catalyzed Suzuki–Miyaura cross-coupling using aryl chlorides.[a]
Eur. J. Org. Chem. 2006, 1917–1925
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1919

C. Wolf, K. Ekoue-Kovi
FULL PAPER
Table 4. (continued)
[
2 3
a] All reactions were carried out with 100 mg of aryl chloride, 1.1 equiv. of boronic acid, 2.5 mol-% of POPd, and 1.5 equiv. of Cs CO
in 3 mL of 1,4-dioxane at 100 °C for 20 h. [b] Isolated yields.
1920
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Pd-Catalyzed Suzuki–Miyaura Cross-Coupling Reactions
FULL PAPER
Table 5. POPd-catalyzed Suzuki–Miyaura cross-coupling using aryl bromides and iodides.[a]
[
3
a] All reactions were carried out with 100 mg of aryl halide, 1.1 equiv. of boronic acid, 2.5 mol-% of POPd, and 1.5 equiv. of Cs
mL of 1,4-dioxane at 100 °C for 20 h. [b] Isolated yields.
2 3
CO in
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1921

C. Wolf, K. Ekoue-Kovi
FULL PAPER
boronic acid 8 was observed to proceed with 74% yields (PXPd, PXPd2, PXPd6, PXPd7) suggested, that these cata-
Entry 4). As expected, POPd-catalyzed cross-coupling of lysts can also be successfully employed in Suzuki–Miyaura
(
arylboronic acids 2 and 4 with quinolyl chlorides 10, 13, coupling reactions. Best results were obtained with POPd
and 15 gave high yields and excellent regioselectivity pro- and PXPd in 1,4-dioxane and ethyl acetate using cesium
viding 7-chloro-4-phenylquinoline (16) in 84% (Entries 5– carbonate as base. Coupling of a range of electron-deficient
8). Under the same conditions, biphenyls 20 and 22 were and electron-rich aryl iodides, bromides, or chlorides and
produced in 72 and 85% yield. The moderate yield of vola- various organoboronic acids in the presence of 2.5 mol-%
tile 3-phenylpyridine (18) obtained by the reaction of 3- of POPd gave the corresponding biaryl products in good to
chloropyridine (17) with 4 can be partially attributed to high yields.
losses during work-up, which also explains why coupling
with 3-bromopyridine (27) gave similar results (compare
Table 4, Entry 9 and Table 5, Entry 3). The synthesis of
Experimental Section
quinoline derivatives continues to be an active area of het-
[
14]
General Procedure: A solution of aryl halide (200 mg), boronic acid
1.1 equiv.), potassium carbonate (1.5 equiv.), and POPd (2.5 mol-
) in 3 mL of 1,4-dioxane was stirred at 100 °C for 20 h. The reac-
erocyclic chemistry. The preparation of 3, 5, 7, 9, 11, 12,
4, and 16 in 74–99% yield is therefore noteworthy since 4-
(
%
1
substituted quinoline derivatives have been reported to dis-
tion mixture was cooled to room temperature, quenched with water
and extracted with dichloromethane. The combined organic layers
were dried with MgSO and the solvents were removed under vac-
4
uum. The residue was purified by flash chromatography on silica
gel as indicated below. NMR spectra were obtained with a Varian
play pronounced biological activities including antimalarial
[
15]
activity.
Good results were also obtained with non-acti-
vated and deactivated aryl chlorides. Coupling of boronic
acid 4 with 2-chlorotoluene (23), 4-chlorotoluene (25) and
electron-rich 4-chloroanisole (27), and 1-chloro-2,5-dimeth- FT-NMR spectrometer at 300 MHz ( H NMR) and 75 MHz ( C
oxybenzene (29), gave biaryls 24, 26, 28, and 30 in 72–80% NMR) using CDCl as the solvent. Chemical shifts are reported in
1
13
3
yield (Entries 12–15). The presence of one ortho-cyano or ppm relative to TMS.
methyl group in 21 and 23, respectively, does not signifi-
4
-(3Ј,5Ј-Dimethylphenyl)-2-methylquinoline (3): Purification by
cantly impede POPd-catalyzed cross-coupling with 4. How-
ever, we found that the reaction proceeds slowly when two
chromatography on silica gel using hexanes/diethyl ether/triethyl-
amine, 100:100:1, gave 3 (260 mg, 93%) as a yellow oil. H NMR:
1
ortho-methyl groups are present, i.e. the reaction of phen- δ = 2.36 (s, 6 H), 2.74 (s, 3 H), 7.06 (s, 3 H), 7.16 (s, 1 H), 7.38
ylboronic acid and 1-chloro-2,6-dimethylbenzene showed (ddd, J = 1.2 Hz, 6.9 Hz, 8.2 Hz 1 H), 7.63 (ddd, J = 1.2 Hz,
less than 50% conversion after 20 h.
In general, coupling of aryl bromides with arylboronic
acids 2 and 4 was found to give excellent yields. Biaryls 30,
6.9 Hz, 8.4 Hz 1 H), 7.87 (dd, J = 1.2 Hz, 8.4 Hz, 1 H), 8.08 (dd,
J = 1.2 Hz, 8.2 Hz, 1 H) ppm. C NMR: δ = 21.6, 25.6, 122.3,
1
3
1
1
25.6, 125.9, 126.1, 127.6, 129.2, 129.5, 130.2, 138.3, 148.4, 148.8,
58.5 ppm. C18 17N (247.14): calcd. C 87.41, H 6.93, N 5.66;
H
32, 34, and 38 were obtained in 82 to 97% (Table 5, Entries
found C 87.18, H 7.32, N 5.59.
1, 2, 5, and 6). The reduced yield of 4-methylbiphenyl (26),
is mostly a consequence of difficulties observed during the 2-Methyl-4-phenylquinoline (5):[5g] Purification by chromatography
chromatographic purification and removal of the starting on silica gel using hexanes/diethyl ether/triethylamine, 100:100:1,
1
material 36 (Entry 4). Employing POPd in Suzuki–Miyaura affords compound 5 (243 mg, 98%) as an orange oil. H NMR: δ
=
2.78 (s, 3 H), 7.21 (s, 1 H), 7.41 (dd, J = 7.3 Hz, 8.1 Hz, 1 H),
cross-coupling of aryl iodides gave a variety of biphenyls in
excellent yields. Using phenylboronic acid 4, we produced
biaryls 41, 43, 45, 47, 49, and 51 in 88 to 99%. Based on
GC/MS analysis, POPd-catalyzed cross-coupling of boronic
acids and aryl bromides or iodides generally proceeds quan-
7.45–7.58 (m, 5 H), 7.68 (dd, J = 7.3 Hz, 8.1 Hz, 1 H), 7.85 (d, J
1
3
=
8.3 Hz, 1 H), 8.12 (d, J = 7.6 Hz, 1 H) ppm. C NMR: δ = 25.7,
1
1
22.5, 125.3, 125.9, 126.0, 128.6, 128.8, 129.3, 129.5, 129.7, 138.4,
48.7, 158.7 ppm.
titatively, but isolated yields are sometimes limited due to Ethyl 4-(2Ј-Methyl-4Ј-quinolyl)benzoate (7):[16] Purification by
chromatography on silica gel using diethyl ether/triethylamine,
difficulties during the separation of reaction products from
small amounts of remaining starting materials exhibiting
similar chromatographic behavior.
1
1
1
7
2
8
00:1, provided a colorless oil of 7 (319 mg, 97%). H NMR: δ =
.44 (t, J = 7.1 Hz, 3 H), 2.78 (s, 3 H), 4.44 (q, J = 7.1 Hz, 2 H),
.22 (s, 1 H), 7.42 (dd, J = 7.3 Hz, 8.3 Hz, 1 H), 7.55 (d, J = 8.1 Hz,
H), 7.69 (dd, J = 7.2 Hz, 7.6 Hz, 1 H), 7.76 (d, J = 8.3 Hz, 1 H),
1
3
.09 (d, J = 8.3 Hz, 1 H), 8.19 (d, J = 8.1 Hz, 2 H) ppm. C NMR:
Conclusion
δ = 14.6, 25.6, 61.4, 122.3, 125.5, 126.3, 129.4, 129.7, 129.8, 130.0,
30.6, 142.9, 147.6, 148.3, 158.5, 166.7 ppm.
1
We have previously shown that palladium–phosphinous
acid complexes afford high yields in Stille, Hiyama, Sonoga-
shira, and Heck reactions. These catalysts are readily avail-
able, recyclable, stable to air and water and therefore easy
to handle. Screening of the efficacy of 11 palladium com-
plexes with monomeric and µ-chloro-bridged dimeric struc-
tures exhibiting either bulky dialkyl- and diarylphosphinous
(
E)-1-(4Ј-Methylphenyl)-2-(2Ј-methyl-4Ј-quinolyl)ethene (9): Purifica-
tion by chromatography on silica gel using hexanes/diethyl ether/
triethylamine, 200:100:1, gave 9 (217 mg, 74%) as a viscous colorless
oil. H NMR: δ = 2.39 (s, 3 H), 2.76 (s, 3 H), 7.21 (d, J = 7.7 Hz, 2
H), 7.27 (d, J = 15.4 Hz, 2 H), 7.42 (s, 1 H), 7.44–7.52 (m, 3 H),
1
[
5g]
13
7
.63–7.72 (m, 2 H), 8.09 (dd, J = 6.4 Hz, 6.9 Hz, 1 H) ppm.
C
NMR: δ = 21.6, 25.7, 117.9, 122.1, 123.5, 125.8, 127.3, 129.5, 129.8,
acid groups (POPd, POPd-Br, POPd1, POPd2, POPd6, 134.1, 134.9, 139.0, 143.3, 158.8 ppm. C H N (259.14): calcd. C
19
17
POPd7, Ph1-Phoxide) or dialkyl(chloro)phosphane ligands 87.99, H 6.61, N 5.40; found C 88.26, H 6.58, N 5.39.
1
922 Eur. J. Org. Chem. 2006, 1917–1925
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Pd-Catalyzed Suzuki–Miyaura Cross-Coupling Reactions
FULL PAPER
(138 mg, 70% from 36) as a colorless oil. H NMR: δ = 2.37 (s, 3
1
4-(3Ј,5Ј-Dimethylphenyl)quinoline (11): Purification by chromatog-
raphy on silica gel using hexanes/diethyl ether/triethylamine,
H), 7.22 (dd, J = 1.2 Hz, 8.1 Hz 2 H), 7.30 (d, J = 8.4 Hz, 1 H),
7.39 (dd, J = 8.1 Hz, 8.1 Hz, 2 H), 7.47 (d, J = 8.1 Hz, 2 H), 7.56
(dd, J = 2.5 Hz, 8.4 Hz, 2 H) ppm. C NMR: δ = 21.5, 127.4,
1
100:100:1, gave 11 (246 mg, 86%) as a yellow oil. H NMR: δ =
2.40 (s, 6 H), 7.10 (s, 3 H), 7.28 (d, J = 3.4 Hz, 1 H), 7.45 (dd, J =
7.5 Hz, 8.5 Hz, 1 H), 7.70 (dd, J = 6.5 Hz, 7.5 Hz, 1 H), 7.95 (d, J
1
3
129.2, 129.9, 131.5, 131.6, 137.6, 138.4, 141.8 ppm.
=
8.5 Hz, 1 H), 8.21 (d, J = 6.5 Hz, 1 H), 8.92 (d, J = 3.4 Hz, 1 H)
4
-Methoxybiphenyl (28):[18] Purification by chromatography on sil-
13
ppm. CNMR: δ = 21.6, 121.5, 126.3, 126.7, 127.2, 127.6, 129.5,
30.1, 130.3, 138.2, 138.4, 149.1, 149.2, 150.2 ppm. C17
233.12): calcd. C 87.52, H 6.48, N 6.00; found C 87.03, H 6.56, N
ica gel using hexanes/diethyl ether, 16:1, gave 28 (207 mg, 80%) as
a colorless oil. H NMR: δ = 3.95 (s, 3 H), 6.94 (dd, J = 2.2 Hz,
6
4
1
(
15
H N
1
.6 Hz, 2 H), 7.23–7.29 (m, 1 H), 7.34–7.41 (m, 2 H), 7.47–7.55 (m,
5.98.
1
3
H) ppm. C NMR: δ = 55.6, 114.6, 127.0, 127.1, 128.5, 129.1,
4
-Phenylquinoline (12):[5g] Purification by chromatography on silica
134.1, 141.2, 159.5 ppm.
gel using hexanes/diethyl ether/triethylamine, 100:100:1, afforded
-Methoxy-2-phenylanisole (30):[19] Purification by chromatography
4
1
12 (249 mg, 99%) as an orange oil. H NMR: δ = 7.25 (d, J =
on silica gel using hexanes/diethyl ether/triethylamine, 800:100:1,
4.4 Hz, 1 H), 7.38–7.50 (m, 6 H), 7.67 (dd, J = 7.3 Hz, 7.3 Hz, 1
1
afforded 30 (192 mg, 97% from 39) as a colorless oil. H NMR: δ
H), 7.89 (d, J = 8.3 Hz, 1 H), 8.21 (d, J = 8.3 Hz, 1 H), 8.91 (d, J
=
3.88 (s, 3 H), 3.94 (s, 3 H), 6.65–6.71 (m, 2 H), 7.34–7.41 (m, 2
=
4.4 Hz, 1 H) ppm. 13C NMR: δ = 121.6, 126.1, 126.9, 127.0,
H), 7.51 (dd, J = 7.5 Hz, 7.5 Hz, 2 H), 7.63 (d, J = 7.3 Hz, 2 H)
128.7, 128.8, 129.6, 129.8, 130.1, 138.2, 148.7, 148.9, 150.2 ppm.
13
ppm. C NMR: δ = 55.7, 55.8, 99.3, 104.9, 124.0, 126.8, 128.3,
129.8, 131.6, 138.8, 157.5, 160.3 ppm.
4-(3Ј,5Ј-Dimethylphenyl)-2-phenylquinoline (14): Purification by
chromatography on silica gel using hexanes/diethyl ether/triethyl-
amine, 800:100:1, provided 14 (243 mg, 94%) as a colorless oil. H
NMR/δ = 2.37 (s, 6 H), 7.08 (s, 1 H), 7.12 (s, 2 H), 7.35–7.51 (m,
-(3Ј,5Ј-Dimethylphenyl)anisole (32):[20] Purification by chromatog-
3
1
raphy on silica gel using hexanes/diethyl ether/triethylamine,
1
7
2
7
00:50:1, afforded 32 (194 mg, 85%) as a yellow oil. H NMR: δ =
4
7
1
1
1
4
H), 7.65 (ddd, J = 1.5 Hz, 7.5 Hz, 7.7 Hz, 1 H), 7.77 (s, 1 H),
.89 (d, J = 8.4 Hz, 1 H), 8.14–8.19 (m, 2 H), 8.21 (d, J = 7.8 Hz,
H) ppm. 13C NMR: δ = 21.7, 119.5, 125.2, 126.1, 126.2, 126.5,
27.7, 127.9, 129.2, 129.6, 129.8, 130.3, 130.5, 138.7, 140.1, 149.2,
49.8, 157.1 ppm. C23H19N (309.15): calcd. C 89.28, H 6.19, N
.53; found C 89.18, H 6.13, N 4.52.
.33 (s, 6 H), 3.78 (s, 3 H), 6.83 (d, J = 8.1 Hz, 1 H), 6.94 (s, 1 H),
.07–7.14 (m, 2 H), 7.17(s, 2 H), 7.24 (dd, J = 8.1 Hz, 8.1 Hz, 1 H)
13
ppm. C NMR: δ = 21.8, 55.6, 113.0, 113.3, 120.1, 125.5, 129.5,
1
30.0, 138.6, 141.6, 143.4, 160.3 ppm.
3
-(3Ј,5Ј-Dimethylphenyl)acetophenone
(34):
Purification
by
chromatography on silica gel using hexanes/diethyl ether/triethyl-
-Chloro-4-phenylquinoline (16):[5g] Purification by chromatography
1
7
amine, 500:50:1, afforded 34 (186 mg, 85%) as a colorless oil. H
on silica gel using hexanes/diethyl ether/triethylamine, 100:100:1,
gave 16 (204 mg, 84%) as a colorless oil. H NMR: δ = 7.29 (d, J
NMR: δ = 2.44 (s, 6 H), 2.69 (s, 3 H), 7.05–7.09 (m, 1 H), 7.26–
7.30 (m, 2 H), 7.55 (ddd, J = 0.6 Hz, 7.7 Hz, 7.7 Hz, 1 H), 7.81
1
=
(
=
4.4 Hz, 1 H), 7.40–7.55 (m, 6 H), 7.91 (d, J = 8.9 Hz, 1 H), 8.09
(ddd, J = 1.1 Hz, 1.9 Hz, 7.7 Hz, 1 H), 7.94 (ddd, J = 1.1 Hz,
d, J = 1.9 Hz, 1 H), 8.98 (d, J = 4.4 Hz, 1 H) ppm. 1 C NMR: δ 1.7 Hz, 7.7 Hz, 1 H), 8.22 (dd, J = 1.7 Hz, 1.9 Hz, 1 H) ppm.
3
13
C
NMR: δ = 21.7, 27.0, 125.4, 127.2, 127.3, 129.2, 129.7, 132.0, 137.8,
138.7, 140.4, 142.2, 198.4 ppm. C H O (224.12): calcd. C 85.68,
121.7, 125.4, 127.6, 127.8, 128.9, 129.0, 129.7, 135.4, 137.7, 148.8,
149.3, 151.2 ppm.
1
6
16
H 7.19; found C 85.12, H 7.12.
3
-Phenylpyridine (18):[5h] Purification by chromatography on silica
2-Phenylnaphthalene (38):[5h] Purification by chromatography on
silica gel using hexanes/diethyl ether/triethylamine, 8000:300:1, gave
38 (184 mg, 93%) as a colorless oil. H NMR: δ = 7.38–7.46 (m, 1
gel using hexanes/diethyl ether/triethylamine, 100:200:1, gave 18
1
(178 mg, 65% from 17) as a colorless oil. H NMR: δ = 7.33–
1
7
=
=
.51 m, 4 H), 7.56–7.61 (m, 2 H), 7.83–7.88 (m, 1 H), 8.59 (dd, J
1.5 Hz, 4.9 Hz, 1 H), 8.86 (d, J = 2.2 Hz, 1 H) ppm. 13C NMR: δ
H), 7.47–7.57 (m, 4 H), 7.74–7.81 (m, 3 H), 7.86–7.92 (m, 3 H),
1
3
123.8, 127.4, 128.4, 129.3, 134.7, 136.9, 138.0, 148.5, 148.6 ppm.
8.08 (s, 1 H) ppm. C NMR: δ = 126.0, 126.3, 126.4, 126.7, 127.6,
1
28.1, 128.7, 128.9, 129.2, 129.3, 133.1, 134.2, 140.0, 141.5 ppm.
3
-Phenylacetophenone (20):[5h] Purification by chromatography on
4
-tert-Butylbiphenyl (41):[21] Purification by chromatography on sil-
silica gel using hexanes/diethyl ether/triethylamine, 200:100:1, pro-
vided 20 (217 mg, 85% from 19) as a oil. H NMR: δ = 2.67 (s, 3
H), 7.39–7.56 (m, 4 H), 7.65 (d, J = 7.3 Hz, 2 H), 7.91 (J = 7.6 Hz,
1
2
1
1
ica gel using hexanes/diethyl ether/triethylamine, 8000:100:1, gave
1
41 (150 mg, 93%) as a colorless oil. H NMR: δ = 1.35 (s, 9 H),
H), 7.96 (d, J = 7.8 Hz, 1 H), 8.23 (s, 1 H) ppm. 13C NMR: δ =
7.0, 127.2, 127.4, 127.5, 128.1, 129.1, 129.4, 131.9, 137.9, 140.0,
41.9, 198.3 ppm.
7.25–7.31 (m, 1 H), 7.35–7.47 (m, 4 H), 7.49–7.59 (m, 4 H) ppm.
1
3
C NMR: δ = 31.8, 126.1, 127.2, 127.4, 129.2, 139.2, 140.1, 150.1
ppm.
-Cyanobiphenyl (22):[5h] Purification by chromatography on silica
3,5-Dimethylbiphenyl (43):[22]
Purification by chromatography on
2
silica gel using hexanes/diethyl ether/triethylamine, 2000:100:1, pro-
gel using hexanes/diethyl ether/triethylamine, 400:100:1, gave 22
1
1
vided 43 (150 mg, 96%) as a yellow oil. H NMR: δ = 2.58 (s, 6
(
207 mg, 72%) as an orange oil. H NMR: δ = 7.37–7.63 (m, 8 H),
.72 (d, J = 8.4 Hz, 1 H) ppm. 13C NMR: δ = 111.5, 118.9, 127.9,
29.0, 129.1, 130.4, 133.2, 134.0, 138.3, 145.7 ppm.
H), 7.19 (s, 1 H), 7.42 (s, 2 H), 7.51 (d, J = 7.5 Hz, 1 H), 7.61 (dd,
7
1
1
3
J = 7.5, 7.7 Hz, 2 H), 7.79 (d, J = 7.7 Hz, 2 H) ppm. C NMR: δ
21.9, 125.6, 127.5, 127.6, 129.1, 129.3, 135.5, 138.6, 142.0, 142.1
=
ppm.
2
-Methylbiphenyl (24):[17] Purification by chromatography on silica
gel using hexanes/diethyl ether, 5:1, gave 24 (200 mg, 75%) as a
1-Phenylnaphthalene (45):[21] Purification by chromatography on
silica gel using hexanes/diethyl ether/triethylamine, 8000:100:1, gave
1
colorless oil. H NMR: δ = 2.27 (s, 3 H), 7.21–7.25 (m, 4 H), 7.27–
.34 (m, 3 H), 7.36–7.42 (m, 2 H) ppm. 1 C NMR: δ = 20.8, 126.1,
27.1, 127.5, 128.4, 129.1, 129.5, 130.1, 130.7, 135.7, 142.3 ppm.
3
7
1
1
4
5 (160 mg, 99%) as a yellow oil. H NMR: δ = 7.26–7.45 (m, 9
1
3
H), 7.79–7.86 (m, 3 H) ppm. C NMR: δ = 125.8, 126.1, 126.4,
127.3, 127.5, 127.6, 128.0, 128.6, 128.9, 129.1, 130.5, 132.0, 134.2,
140.6, 141.1 ppm.
4
-Methylbiphenyl (26):[5h] Purification by chromatography on silica
gel using hexanes/diethyl ether/triethylamine, 8000:100:1, gave 26
Eur. J. Org. Chem. 2006, 1917–1925
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
1923

C. Wolf, K. Ekoue-Kovi
FULL PAPER
4
-Phenylacetophenone (47):[22] Purification by chromatography on
silica gel using hexanes/diethyl ether/triethylamine, 700:50:1, gave
dick, F. G. N. Cloke, N. C. Billingham, P. B. Hitchcock, J. Leo-
nard, J. Am. Chem. Soc. 2003, 125, 10066–10073; h) O. Nav-
arro, R. A. Kelly III, S. P. Nolan, J. Am. Chem. Soc. 2003, 125,
1
47 (140 mg, 88%) as a colorless oil. H NMR: δ = 2.65 (s, 3 H),
11818–11819.
7
.42–7.53 (m, 3 H), 7.64–7.72 (m, 4 H), 8.06 (d, J = 6.6 Hz, 2 H)
[
5] a) G. Y. Li, Angew. Chem. Int. Ed. 2001, 40, 1513–1516; b)
13
ppm. C NMR: δ = 26.9, 127.5, 127.5, 128.5, 129.2, 129.3, 136.1,
1
G. Y. Li, G. Zheng, A. F. Noonan, J. Org. Chem. 2001, 66,
40.0, 146.0, 198.0 ppm.
8677–8681; c) G. Y. Li, J. Org. Chem. 2002, 67, 3643–3650; d)
-Phenylanisole (49):[5g] Purification by chromatography on silica
C. Wolf, R. Lerebours, J. Org. Chem. 2003, 68, 7077–7084; e)
C. Wolf, R. Lerebours, E. H. Tanzini, Synthesis 2003, 2069–
2073; f) W. Yang, Y. Wang, J. R. Corte, Org. Lett. 2003, 5,
3
gel using hexanes/diethyl ether/triethylamine, 8000:100:1, gave 49
1
(
(
142 mg, 91%) as a yellow oil. H NMR: δ = 3.95 (s, 3 H), 7.02
dd, J = 2.7 Hz, 8.4 Hz, 1 H), 7.16–7.26 (m, 2 H), 7.35–7.51 (m, 2
3131–3134; g) C. Wolf, R. Lerebours, J. Org. Chem. 2003, 68,
7551–7554; h) C. Wolf, R. Lerebours, Org. Lett. 2004, 6, 1147–
1150; i) C. Wolf, R. Lerebours, Org. Biomol. Chem. 2004, 2,
2161–2164.
13
H), 7.52–7.68 (m, 2 H), 7.74 (d, J = 8.1 Hz, 2 H) ppm. C NMR:
δ = 55.6, 113.0, 113.3, 120.0, 127.6, 127.8, 129.1, 130.1, 141.5,
1
43.0, 160.2 ppm.
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3
gel using hexanes/diethyl ether/triethylamine, 1000:500:1, provided
5
H), 7.56–7.64 (m, 3 H), 7.91 (d, J = 7.6 Hz 1 H), 8.19 (d, J =
8
1
1
1 (156 mg, 98%) as a yellow oil. H NMR: δ = 7.41–7.51 (m, 3
.2 Hz 1 H), 8.44 (s, 1 H) ppm. 13C NMR: δ = 122.2, 122.3, 127.4,
27.5, 128.8, 129.4, 130.0, 133.3, 138.5, 143.0 ppm.
70, 2191–2194.
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2006, 1917–1925

Pd-Catalyzed Suzuki–Miyaura Cross-Coupling Reactions
FULL PAPER
[
[
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Received: October 28, 2005
1
3
Published Online: February 6, 2006
2
Eur. J. Org. Chem. 2006, 1917–1925
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
1925