Palladium-catalyzed Suzuki-Miyaura cross-coupling of various aryl halides using ortho-alkyl-substituted arylphosphanes and (ortho-alkylphenyl)- alkylphosphanes under microwave heating

Article abstract of DOI:10.1002/ejic.200700705

Mono- and dinuclear palladium(II) chloride complexes of various ortho-alkyl-substituted aryl- and alkylphosphanes were prepared. Subsequently, these were characterized by ¹H NMR and ³¹P{¹H} NMR spectroscopy, X-ray crystallographic studies and mass spectroscopy. The palladium complexes were screened as potential catalysts for the microwave-assisted Suzuki-Miyaura coupling reaction of several aryl halides under aerobic conditions. A preliminary study showed that excellent results can be obtained even for electron-rich bromides and unactivated aryl chlorides with an optimized solvent, base and catalyst loading using specific phosphane ligands. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejic.200700705

FULL PAPER
DOI: 10.1002/ejic.200700705
Palladium-Catalyzed Suzuki–Miyaura Cross-Coupling of Various Aryl Halides
Using ortho-Alkyl-Substituted Arylphosphanes and (ortho-Alkylphenyl)-
alkylphosphanes under Microwave Heating
Sauli Vuoti,*[a] Juho Autio,[a] Minna Laitila,[a] Matti Haukka,[b] and Jouni Pursiainen[a]
Keywords: Alkylphosphane / Palladium complex / Microwave-assisted synthesis / Cross-coupling
Mono- and dinuclear palladium(II) chloride complexes of
various ortho-alkyl-substituted aryl- and alkylphosphanes
were prepared. Subsequently, these were characterized by
1H NMR and 31P{1H} NMR spectroscopy, X-ray crystallo-
graphic studies and mass spectroscopy. The palladium com-
plexes were screened as potential catalysts for the micro-
wave-assisted Suzuki–Miyaura coupling reaction of several
aryl halides under aerobic conditions. A preliminary study
showed that excellent results can be obtained even for elec-
tron-rich bromides and unactivated aryl chlorides with an op-
timized solvent, base and catalyst loading using specific
phosphane ligands.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
alkylphosphane classes have been studied for these reac-
tions, with promising results.[17–18] The effectiveness of these
types of ligands has been reported to be caused mainly by
the high resistance towards oxidation.[19] However, there are
also reports of ligand-free Pd/C catalysts, which bypass the
waste formation caused by phosphane ligands.[20] Further-
more, De Vries et al. have successfully employed ultra low
catalyst loadings in Suzuki coupling reactions.[21] Even if
several new ligands with enhanced properties in assisting
the palladium-catalyzed coupling have been developed, a
universal method for the coupling of all substrates has not
yet been entirely elucidated.[22]
Blettner et al. were the first to describe the use of the
Suzuki coupling reaction for the coupling of various benzo-
ates and phenylboronic acid using microwave irradiation.[23]
Using microwave irradiation and metal catalysts has been
often described in combination with green chemistry.[24]
The choice of using microwave heating instead of conven-
tional heating methods further enhances the effectiveness
and rapidity of the coupling reactions. This in turn, creates
new options and increases demand for the design of new
ligands.[25] Access to new types of ligands is therefore a crit-
ical component of the design of novel homogeneous transi-
tion-metal catalysts. Even if the less demanding and less
active furanones[26] and electron-rich aryl bromides have al-
ready been coupled with environmentally friendly solvents
and ligand-free procedures using microwave irradiation,[27]
research on the microwave-assisted Suzuki–Miyaura coup-
ling reactions has been concentrated on the coupling of un-
activated aryl chlorides, which are much cheaper starting
materials. Unactivated aryl chlorides have been successfully
coupled using recyclable PEG-catalysts[28] and even ligand-
Introduction
Transition-metal-catalyzed cross-coupling is now recog-
nized to be one of the most powerful carbon–carbon bond
forming reactions. Palladium-catalyzed carbon–carbon and
carbon–nitrogen bond-forming reactions are widely used
methods in modern organic chemistry. The Pd-catalyzed
Suzuki–Miyaura coupling reaction is one of the most con-
venient methods for preparing biaryl compounds thanks to
the advantages of wide functional group tolerance and the
use of stable and nontoxic organoborane reagents.[1–7] The
palladium-catalyzed coupling of aryl halides or their syn-
thetic equivalents are very often used in the synthesis of
biaryl molecules. These are key components in a growing
number of pharmaceuticals, natural products and with axial
chiral ligands highly efficient asymmetric catalysts.[2,4,8]
Since the general catalytic procedures were discovered, ef-
forts have been made toward increasing the substrate range
and efficiency. Although the use of alternative bases or sol-
vents can be beneficial, it is the electronic and steric im-
provement of the supporting ligand that has the most influ-
ence on increasing efficiency and reactivity in these pro-
cesses.[9–16] Consequently, designing ligands that have the
appropriate features with sufficient variety is decisive in
dealing with the demanding substrates in this area. Typi-
cally, the electron-rich and sterically hindered ligands be-
longing to the trialkylphosphane, aryldialkyl- and diaryl-
[a] Department of Chemistry, University of Oulu,
P. O. Box 3000, 90014 Oulu, Finland
Fax: +358-8-5531603
E-mail: sauli.vuoti@oulu.fi
[b] Department of Chemistry, University of Joensuu,
P. O. Box 111, 80101 Joensuu, Finland
Eur. J. Inorg. Chem. 2008, 397–407
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
397

S. Vuoti, J. Autio, M. Laitila, M. Haukka, a., J. Pursiainen
FULL PAPER
free processes,[29] but when microwave irradiation is em- by a similar 1:1 substitution reaction in dichloromethane.
ployed, the coupling of unactivated aryl chlorides can only We have previously shown that depending on the solvent
be achieved with limited success.[30]
used ortho-alkyl-substituted arylphosphanes form mono-
In this study we synthesized and characterized four new or dinuclear palladium complexes regardless of the Pd/P
ortho-alkyl-substituted arylalkylphosphanes and their cor- ratio.[31]
responding palladium(II) complexes. Together with a selec-
tion of palladium(II) arylphosphane complexes charac-
terized in our previous work,[31] and new palladium com-
plexes prepared with previously known aryl(alkyl)phos-
phanes,[32–35] all these were screened and compared as
potential catalysts for the Suzuki–Miyaura coupling of
various aryl halides under microwave irradiation.
Results and Discussion
Scheme 2. A general reaction scheme for the preparation of the
mono- and dinuclear palladium complexes.
Syntheses and characterization of the ortho-alkyl-substi-
tuted arylalkylphosphane ligands and their corresponding
palladium complexes
The new phosphane ligands 2a, 2b, 2d and 3a (Scheme 1)
were prepared according to a modified method reported in
the literature[34–35] by lithiating the substituted bromoben-
zenes with n-butyllithium followed by an overnight reaction
between the matching dichloroalkyl- or dialkylchlorophos-
phane. The phosphanes were characterized by 1H, 13C,
31P{1H} NMR and mass spectroscopy.
The phosphane ligand 4b forms a regular trans-isomer in
the synthesis of the mononuclear palladium complex. How-
ever, a cis-sym-isomer was crystallized after the synthesis of
the matching dinuclear complex. Variable temperature 31P
NMR measurements between –50 °C and 60 °C show just
one NMR signal, which suggests the presence of only one
isomer in solution. This is probably due to attractive inter-
actions between two ligands. Such a phenomenon has been
previously known.[36] To the best of our knowledge, this is
the first time a dinuclear cis-sym palladium complex has
been used successfully as a catalyst in Suzuki coupling reac-
tions. However, the use of dinuclear Pd complexes in allyl
substitutions reactions has been reported previously.[37] The
palladium complexes were characterized by 31P{1H} NMR,
elemental analysis and X-ray crystal diffraction (where ap-
plicable). The palladium complexes are not soluble enough
1
to produce proper H NMR spectra. However, overnight
1H NMR measurements for a few mono- and dinuclear
Scheme 1. Structures of the new phosphanes 2a, 2b, 2d and 3a.
Figure 1. Thermal ellipsoid plot of the mononuclear palladium
complex of ligand 2a. Selected bond lengths (Å) and angles (°):
Pd1–Cl1 2.2869(11), Pd1–P1 2.3189(12), P1–C11 1.806(5), P1–C1
1.817(5), P1–C9 1.830(5), Cl1–Pd1–P1 87.76(4), Cl1(A)–Pd1–P1
92.24(4). Symmetry transformations were used to generate equiva-
All the new and previously known mononuclear palladi-
um(II) complexes were prepared by a simple 1:2 substitu-
tion of cyclooctadiene (cod) in PdCl2(cod) with a preferred
phosphane ligand in diethyl ether (Scheme 2). The dinu-
clear, chlorine-bridged palladium complexes were prepared lent atoms: (A) –x + 2, y, –z + 2.
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Pd-Catalyzed Suzuki–Miyaura Cross-Coupling
complexes showed that the shifts of the hydrogen atoms had and 2c the atoms bonded to the Pd centers form two square
moved downfield only slightly, and therefore the measure- planes. The neighboring planes are nearly coplanar in 2d
ments were not repeated for the other complexes.
and 2c, but in 4c the planes defined by Cl1, Cl2, P1, Cl3
In all complexes the Pd atoms have square planar or and Cl1, Cl2, Cl4, P2 are slightly bent. The angle between
slightly disordered square-planar coordination geometry the planes is 25.80(2)°.
(see Figures 1, 2, 3, and 4). In the mononuclear complexes
of ligands 4b, 2c, 2b, 2a and 2d the Pd atom is located
on an inversion center. In the complex of ligand 2d the
inversion center is located between the Pd atoms. The
Pd–P [2.2224(13)–2.2397(11) Å], Pd–Clterminal [2.2869(11)–
2.3745(15) Å], Pd–Clbridging [2.25(5)–2.4351(10) Å] and
Pd–S [2.2550(13)–2.2710(16) Å] distances fall into the range
of typical bond lengths. The short Pd–Clbridging (2.25 Å) dis-
tance is most probably due to the elemental disorder in
structure 2a. In the dinuclear complexes of ligands 2d, 4c
Figure 4. Thermal ellipsoid plot of the dinuclear palladium com-
plex of ligand 4b. The solvent has been omitted for clarity. Selected
bond lengths (Å) and angles (°): Pd1–P1 2.244(3), Pd1–Cl1
2.286(4), Pd1–Cl2 2.342(3), Pd1–Cl3 2.399(3), Pd2–P2 2.244(3),
Pd2–Cl4 2.287(3), Pd2–Cl2 2.318(3), Pd2–Cl3 2.406(3), Pd1–Cl2–
Pd2 91.67(12), Pd1–Cl3–Pd2 88.17(11), P1–Pd1–Cl1 86.80(13), P2–
Pd2–Cl4 87.37(12).
Suzuki Coupling of Arylboronic Acids with Aromatic
Figure 2. Thermal ellipsoid plot of the mononuclear palladium
Halides
complex of ligand 2b. Selected bond lengths (Å) and angles (°):
Pd1–Cl1 2.3065(4), Pd1–P1 2.3373(4), P1–C1 1.842(2), P1–C10
1.855(2), P1–C13 1.858(2), Cl1–Pd1–P1 88.815(15), Cl1(A)–Pd(1)–
P(1) 90.911(15). Symmetry transformations were used to generate
To create the optimum conditions for the coupling reac-
tions, the catalyst loading, base and solvent were screened
using the simple coupling reaction of 4-bromotoluene and
phenylboronic acid (Scheme 3). Using 0.5 mol-% of the pal-
ladium catalyst provided the best result whereas using
larger or smaller amounts of the catalyst did not improve
the yield further (see Table 1). We also tested a series of
bases for the aforementioned coupling reaction. According
to a report by Bele et al.,[38] K2CO3 is an effective base
for many Pd-catalyzed coupling reactions under microwave
irradiation. Our results confirmed this by showing that both
K2CO3 and K3PO4 were indeed effective bases (see Table 2,
Entries 1 and 3). Our solvent screening data revealed that
DMF and THF were the most effective solvents for the
coupling reaction (see Table 3, entries 4 and 5).
equivalent atoms: –x + 1, y, –z + 1/2.
Utilizing the optimized reaction conditions, we evaluated
the scope of the coupling of various aryl and heteroaryl
halides with phenylboronic acid and biphenylboronic acid
using palladium catalysts with a variety of phosphane li-
gands. The results are presented in Tables 4 and 5. All yields
were reported as isolated yields after separation of the prod-
ucts by column chromatography.
The results show that the palladium complexes of the
arylphosphane ligands produce high yields when simple
substrates such as 3-bromotoluene or 3-bromopyridine are
Figure 3. Thermal ellipsoid plot of the dinuclear palladium com-
plex of ligand 2c. Selected bond lengths (Å) and angles (°): Pd1–
P1 2.2397(11), Pd1–Cl3 2.290011, Pd1–Cl2 2.3277(11), Pd1–Cl1
2.4351(10), Pd2–P2 2.2341(11), Pd2–Cl4 2.2922(11), Pd2–Cl1
2.3350(11), Pd2–Cl2 2.4106(10). Cl3–Pd1–Cl2 175.08(4), P1–Pd1–
Cl1 175.90(4), Cl4–Pd2–Cl1 174.68(4), P2–Pd2–Cl2 177.82(4),
Pd2–Cl1–Pd1 90.94(4), Pd1–Cl2–Pd2 91.73(4).
Eur. J. Inorg. Chem. 2008, 397–407
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S. Vuoti, J. Autio, M. Laitila, M. Haukka, a., J. Pursiainen
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Scheme 3. Structures of the phosphanes used in the coupling reactions.
Table 2. Screening of bases for the reaction of 4-bromotoluene and
phenylboronic acid.[a]
Table 1. Screening of the catalyst loading for the reaction of 4-
bromotoluene and phenylboronic acid.[a]
% Yield[b]
Entry
mol-%
% Yield[b]
Entry
Base
1
2
3
4
5
6
7
0.05
0.1
0.5
1.0
2.5
5.0
10.0
41
73
99
77
90
92
81
1
2
3
4
5
6
K3PO4
Na2CO3
K2CO3
KOH
88
63
99
59
55
94
KF
[c]
K2CO3
[a] Reaction conditions: 4-bromotoluene (1.45 mmol, 1.0 equiv.),
phenylboronic acid (1.65 mmol, 1.14 equiv.), base (3.0 mmol,
2.1 equiv.), DMF (2.5 mL). [b] Isolated yield after column
chromatography. [c] 4.0 mmol, 2.8 equiv.
[a] Reaction conditions: 4-bromotoluene (1.45 mmol, 1.0 equiv.),
phenylboronic acid (1.65 mmol, 1.14 equiv.), K2CO3 (3.0 mmol,
2.1 equiv.), DMF (2.5 mL).. [b] Isolated yield after column
chromatography.
Table 3. Screening of solvents for the reaction of 4-bromotoluene
and phenylboronic acid.[a]
coupled, but the yields start to decrease when more de-
manding substrates such as bromoxylenes or trimethyl-
bromobenzenes are used. The palladium complexes of the
hetero-atom substituted phosphane ligands 4e and 4f are
only mildly active as catalysts in all reactions. The aryl-
(alkyl)phosphane ligands produce high yields in all reac-
tions with only minor differences between the yields. The
various size ortho-substituents influenced the yields only
slightly. The dinuclear palladium complexes produced lower
yields than the corresponding mononuclear complexes in
all reactions.
Entry
Solvent
% Yield[b]
1
2
3
4
5
water
toluene
ethanol
26
68
83
87
99
tetrahydrofuran
DMF
When the more challenging biphenylboronic acid is used,
the results are similar as the ones received in the reactions
with phenylboronic acid. The palladium complexes of the
aryl(alkyl)phosphane ligands produce higher yields than the
[a] Reaction conditions: 4-bromotoluene (1.45 mmol, 1.0 equiv.),
phenylboronic acid (1.65 mmol, 1.14 equiv.), K2CO3 (3.0 mmol,
2.1 equiv.), solvent (2.5 mL). [b] Isolated yield after column
complexes of the arylphosphanes. The yields produced with chromatography.
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Pd-Catalyzed Suzuki–Miyaura Cross-Coupling
Table 4. Coupling of aryl halides with phenylboronic acid.[a]
[a] Standard reaction conditions: aryl halide (1.45 mmol, 1.0 equiv.), phenylboronic acid (1.65 mmol, 1.15 equiv.), K2CO3 (3.0 mmol,
2.0 equiv.), DMF (2.5 mL), 0.5 mol-% of Pd catalyst, MW (150 °C, 30 min). [b] Dinuclear palladium complex of the Pd2Cl4L2-type.
the complexes of the bulkier aryl alkyl ligands 3a, 3b and
The palladium complexes of the mixed aryl(alkyl)phos-
2d were somewhat lower than the ones produced with the phane ligands 2a–3b gave the highest yields in most coup-
smaller ligands 2a–2c.
ling reactions with only small differences between the yields.
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S. Vuoti, J. Autio, M. Laitila, M. Haukka, a., J. Pursiainen
Table 6. Coupling of aryl halides with phenylboronic acid.[a]
FULL PAPER
Table 5. Pd-catalyzed coupling of 4-bromotoluene and 2-biphen-
ylboronic acid.[a]
Entry
Pd catalyst
Isolated yield (%)
1
2
3
4
5
6
7
8
2b
2c
96
90
86
77
77
76
70
68
64
51
40
2a
3a
3b
4d
2d
4a[b]
4b
1a
4f
9
10
11
[a] Reaction conditions: 4-bromotoluene (1.45 mmol, 1.0 equiv.),
biphenylboronic acid (1.64 mmol, 1.14 equiv.), K2CO3 (3.0 mmol,
2.1 equiv.), DMF (2.5 mL), 0.5 mol-% of Pd catalyst. [b] Dinuclear
palladium complex of the Pd2Cl4L2-type.
Overall, ligand 2b was observed to be the most efficient
catalyst for most couplings, although the other aforemen-
tioned ligands gave almost equally as high yields in several
reactions. The combination of two isopropyl groups directly
connected to the phosphorus atom with one ortho-isoprop-
yl-substituted phenyl ring seemed to be the optimal struc-
ture even for the most demanding coupling reactions in our
[a] Standard reaction conditions: aryl halide (1.45 mmol,
1.0 equiv.), phenylboronic acid (1.65 mmol, 1.15 equiv.), K2CO3
(3.0 mmol, 2.0 equiv.), DMF (2.5 mL), H2O (0.5 mL), 0.5 mol-%
of PdCl2(2b)2, MW (150 °C, 30 min).
All the coupling reactions conducted by using the mono-
screening. Increasing the size of the isopropyl groups di- nuclear palladium complex of ligand 2b as the catalyst pro-
rectly connected to the phosphorus atom to cyclohexyl duced high yields. The coupling reaction between the 4-bro-
groups or decreasing the size to ethyl groups was observed mobenzaldehyde and phenylboronic acid was the only ex-
to lower the yields. Altering the ortho-substituent on the ception, only a 65% yield was achieved by our method. The
phenyl ring from methyl to isopropyl only slightly affected coupling reactions seem to produce high yields regardless
the yields. However, increasing the size of the substituent to of the functional group of the aryl substrate. Even the unac-
a phenyl ring somewhat lowered the yield.
tivated aryl chlorides, which of the 3-bromo-o-xylene is the
The palladium complexes with classic triphenylphos- most demanding one, were coupled successfully with high
phane moieties worked well in simple coupling reactions, yields.
but mostly produced only low to mediocre yields in the
Preliminary testing showed that some of the starting ma-
more demanding couplings. The triphenylphosphane palla- terials remained unreacted in the reaction mixture. Conse-
dium complexes with thiomethyl and methoxy groups in the quently, the reaction was further enhanced by the addition
ortho position produced only low to mediocre yields, which of a small amount of water, which is reported to enhance
was probably due to the respective chelated structure. Such the yields even further.[39] In our studies it also improved
a phenomenon has been previously observed in various hy- the purity of the coupling products and prevented homo-
droformylation reactions.[32] The dinuclear palladium com- coupling of the phenylboronic acid.
plexes produced average yields in the simplest reactions, but
a fast disintegration of the complexes was detected and eroaryl halides with phenylboronic acid by using K2CO3
therefore high yields were not achieved. (2 equiv.)/Pd catalyst (2b) (0.5%) system in DMF/H2O gave
The coupling of various more demanding aryl and het-
Due to promising results with the coupling reactions pre- good to excellent yields of the corresponding bi and ter-
sented above, our studies continued using a series of more phenyls. Even the normally mildly reactive aryl chlorides
challenging, electron-rich aryl bromides and unactivated were successfully coupled providing high yields. Further
aryl chlorides in the coupling reactions. The results are pre- testing for these potential catalysts are currently underway
sented in Table 6.
in our laboratory.
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Pd-Catalyzed Suzuki–Miyaura Cross-Coupling
The microwave cavity was tuned for 2–5 mL samples. The sample
was heated to the desired temperature using 150 W power. The
power was set 0 W immediately after reaching the preset tempera-
ture, and the sample was irradiated as needed to maintain the tem-
Conclusions
In conclusion, we prepared four new ligands suitable for
microwave -assisted Pd-catalyzed Suzuki–Miyaura coupling
of aryl bromides and chlorides with phenylboronic acids. perature. The 30 min heating period was started when the tempera-
ture of the sample had reached 150 °C. Cooling was not used while
heating the sample. After the preset heating period, the reaction
vessel was cooled to room temperature using airflow.
The ligands are relatively cheap due to the low catalyst
loadings and can be readily prepared from commercially
available reagents. To avoid difficulties caused by in situ
generated systems,[40] such as the requirement for an excess
of expensive ligands, we have used air- and moisture-stable
X-ray Crystal Structure Determinations: The crystals were im-
mersed in cryo-oil, mounted in a Nylon loop and measured at a
palladium(II) complexes, which allow strict control over the temperature of 110 or 120 K. The X-ray diffraction data were col-
lected by means of a Nonius KappaCCD diffractometer using Mo-
Kα radiation (λ = 0.71073 Å) resolution. The DENZO-SCALE-
PACK[42] or EvalCCD[43] program packages were used for cell re-
finements and data reductions. All of the structures were solved
by direct methods using the SHELXS97,[44] SIR92,[45] SIR97,[46]
SIR2004[47] with the WinGX[48] or X-SEED[49] graphical user inter-
face. An empirical absorption correction factor was applied to all
of the data (SADABS,[50] XPREP in SHELXTL v.6.14-1[51]). Struc-
tural refinements were carried out using SHELXL97.[52] The crys-
tallographic data of 2a, 2b, 2c, and 4b are summarized in Table 7.
palladium/ligand ratio and remain stable in organic solvents
at high temperatures. Furthermore, the reactions can take
place in air. Microwave heating provides several advantages
in comparison to conventional heating methods. Microwave
heating gives shorter reaction times, and in most cases im-
proves product yields.[23,27,39–40] Other advantages include:
new avenues for synthesis not achieved by using conven-
tional heating methods and the avoidance of lengthy metal
catalyst extraction steps.[41] The addition of a small amount
of water into the reaction mixture further enhances the The thermal ellipsoid plots of three representative palladium com-
plexes of ligands 2a–c and 4b are shown in Figures 1–4. The crys-
tallographic data for the PdII complexes of ligands 2a–2d, 3a–b,
4a–4c and 4e–f have been deposited with the Cambridge Crystallo-
graphic Data Centre under supplementary publication numbers:
CCDC-644388 (for 2a), -644389 (for 2d), -644390 (for 3a), -644391
(for 3b), -644392 (for 4a), -644393 (for 4b), -644394 (for 4c),
-644395 (for 4e), -644396 (for 4f), -644397 (for 2d), -644398 (for
3a), -652017 (for 4e), and -652018 (for 4f). Copies of this infor-
mation can be obtained free of charge on application to CCDC,
12 Union Road, Cambridge CB2 1ET, UK [Fax: +44 1223 336033;
E-mail: deposit@ccdc.cam.ac.uk].
yields and the purity of the coupling products. The catalyst
system can therefore be used even for the electron-rich bro-
mides and unactivated aryl chlorides. Further testing is cur-
rently underway in our laboratory.
Experimental Section
General: The prepared phosphanes are air- and moisture sensitive,
both as pure solid compounds and in solution. Without protection
they undergo observable oxidation within a few hours. Therefore
all reactions involving these free phosphanes were carried out using
standard Schlenk techniques under either nitrogen or argon. The
palladium complexes are stable in air, both as solid compounds
and in solution, and were therefore isolated and characterized in
air. Diethyl ether was distilled from sodium-benzophenone ketyl
under nitrogen before use. Nitrogen was bubbled through dichloro-
methane, ethanol and n-hexane. Other commercial reagents were
used as obtained. The characterization of the new phosphanes and
the palladium complexes was based on 1H-, 31P{1H} and 13C-NMR
spectroscopy. NMR spectra were recorded with a Bruker DPX400
or DPX200 spectrometer at room temperature in CDCl3 (99.8%
D, 0.03% TMS). 85% H3PO4 was used as an external standard for
31P{1H} NMR spectroscopy. Exact mass peaks of the free ligands
were determined on a Micromass LCT, using an ESI+ method. C
and H analyses were made using a Perkin–Elmer 2400 CHNS
analyzer from the purified, solid metal complex powders. The mass
peaks for the coupling products were determined by a Hewlett
Packard HP 6890 Series GC-system coupled to a 5973-MSD (Mass
Selective Detector, quadrupole). Single-crystals for X-ray crystallo-
graphic analysis were obtained by slow evaporation of the dichloro-
methane/hexane solvent mixture at room temperature.
A General Method for the Preparation of the ortho-Alkyl-Substi-
tuted Aryl(alkyl)phosphane Ligands 2a, 2b, 2d, and 3a: A solution
of n-butyllithium was transferred dropwise by a cannula to a freshly
prepared solution of 1-bromo-2-alkylbenzene in diethyl ether
(30 mL) at –10 °CǞ0 °C (salted ice bath). After stirring for 3 h, a
solution of dialkylchlorophosphane or dichloroalkylphosphane in
diethyl ether (25 mL) was slowly added to the mixture, and the
mixture was stirred at room temperature overnight. The liquid was
removed, and the solid was extracted three times with diethyl ether
(10 mL). The liquid layers were combined and the solvent was
removed in vacuo. The crude product was recrystallized from etha-
nol, and if necessary, purified by column chromatography using
dichloromethane/hexane (1:2) mixture as eluent. The pure products
were bright viscous oils or white solids. The previously known
phosphanes were prepared according to methods reported in the
literature.[34–35]
Diethyl(o-ethylphenyl)phosphane (2a): Following the general pro-
cedure described above, reactions of 1-bromo-2-ethylbenzene
(7.373 g, 39.8 mmol), n-butyllithium (16 mL, 2.5 , 40.0 mmol) and
chlorodiethylphosphane (5 g, 40.1 mmol) yielded a bright viscous
oil after recrystallization from ethanol and purification by column
chromatography. The yield of the pure product was 7.503 g,
38.6 mmol, 97.0%. Exact mass (Micromass LCT, ESI+): 195.1333
[M + H]+ (calculated for C12H20P, 195.1303). 1H NMR (200 MHz,
The microwave system was Biotage Initiator Eight. The microwave
reactor was from Biotage (personal Chemistry) Emrys syntheziser,
where temperature, pressure and microwave power can be con-
trolled. The reaction vessel used was a 2–5 mL closed tube. The
maximum pressure was 21 bar, the maximum temperature 250 °C
and the maximum microwave power 300 W. Temperatures were
measured with an IR thermometer. The reactor was a single mode
reactor, where the microwave cavity is tuned for each sample, so
that absorption of microwaves is at the highest possible level.
3
CDCl3, see Scheme 1 for numbering): δ = 1.14 (t, JH,H = 4.6 Hz,
3
3 H, H8), 1.36 (t, JH,H = 5.2 Hz, 6 H, H9), 2.02 (m, 4 H, H10),
2.95 (m, 2 H, H7), 7.15–7.55 (m, 4 H, H3, H4, H5, H6) ppm.
13C{1H} NMR (100 MHz, CDCl3): δ = 5.82 (s, 1 C, C9), 5.86 (s, 1
C, C9), 16.32 (s, 1 C, C8), 22.26 (s, 1 C, C10), 22.95 (s, 1 C, C10),
Eur. J. Inorg. Chem. 2008, 397–407
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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403

S. Vuoti, J. Autio, M. Laitila, M. Haukka, a., J. Pursiainen
Table 7. Crystallographic data for the mononuclear palladium complexes 2a–b and dinuclear 2c and 4b.
FULL PAPER
2a
2b
2c
4b
Empirical formula
Fw
Temperature [K]
C24H38Cl2P2Pd
565.78
120(2)
C30H50Cl2P2Pd
649.94
120(2)
C34H42Br2Cl6P2Pd2
1097.94
120(2)
C43H43Cl7P2Pd2
1082.66
120(2)
λ [Å]
Crystal system
Space group
0.71073
0.71073
monoclinic
C2/c
0.71073
monoclinic
P21/n
0.71073
monoclnic
P21/c
triclinic
¯
P1
a [Å]
b [Å]
c [Å]
α [°]
7.4317(3)
8.7296(5)
10.5167(6)
75.711(2)
74.582(3)
82.901(4)
636.15(6)
1
1.477
1.075
10419
2626
17.8026(5)
10.7622(3)
18.1899(3)
90
111.748(2)
90
3237.04(15)
4
1.334
0.854
22864
3717
0.0418
7.63530(10)
21.3959(5)
12.4927(3)
90
90.654(2)
90
2040.73(7)
2
1.787
3.335
27952
4674
0.0435
18.4500(17)
12.2249(13)
21.012(2)
90
113.374(5)
90
4350.2(8)
4
1.653
1.362
46424
7653
0.2702
β [°]
γ [°]
V [Å3]
Z
ρcalc [Mg/m3]
µ (Mo-Kα) [mm–1]
Number of collected reflections
Number of unique reflections
Rin[4t.2]
0.0621
0.0499
0.1312
R1 [IՆ2σ]
0.0260
0.0570
0.0436
0.1124
0.0826
0.1575
[44]
wR2 [IՆ2 σ]
3
27.58 (d, JC,P = 16 Hz, 1 C, C7), 125.46 (s, 1 C, C4), 125.48 (s, 1 (4.61 g, 27.0 mmol), n-butyllithium (10.8 mL, 2.5 , 27.0 mmol)
1
C, C5), 129.96 (s, 1 C, C6), 130.06 (s, 1 C, C3), 131.69 (d, JC,P
=
and dichloroethylphosphane (3.522 g, 26.9 mmol) yielded a bright
viscous oil after recrystallization from ethanol and purification by
column chromatography. The yield of the pure product was
(5.839 g, 24.1 mmol, 89.6%). Exact mass (Micromass LCT, ESI+):
8 Hz, 1 C, C2), 131.84 (d, JC,P = 10 Hz, 1 C, C1) ppm. 31P{1H}
2
NMR (161 MHz, CDCl3): δ = –31.5 ppm.
Diisopropyl(o-isopropylphenyl)phosphane (2b): Following the gene-
ral procedure described above, reactions of 1-bromo-2-iso-
propylbenzene (4.903 g, 24.6 mmol), n-butyllithium (9.8 mL, 2.5 ,
24.5 mmol) and chlorodiisopropylphosphane (3.710 g, 24.3 mmol)
yielded a white solid product after recrystallization from ethanol.
The yield of the pure product was (5.434 g, 23.0 mmol, 94.6%).
Exact mass (Micromass LCT, ESI+): 237.1766 [M + H]+ (calcu-
lated for C15H26P, 237.1772). 1H NMR (200 MHz, CDCl3, see
1
243.1296 [M + H]+ (calculated for C16H20P, 243.1303). H NMR
(200 MHz, CDCl3, see Scheme 1 for numbering): δ = 1.18 (m, 3 H,
H8), 1.34 (m, 2 H, H9), 2.60 (s, 6 H, H7), 7.16 (m, 2 H, H5), 7.30–
7.43 (m, 6 H, H2–4,6) ppm. 13C{1H} NMR (100 MHz, CDCl3): δ =
2
10.42 (d, JC,P = 18.4 Hz, 1 C, C8), 20.14 (s, 1 C, C9), 21.51 (d,
3JC,P = 20.7 Hz, 2 C, C7), 126.27 (s, 2 C, H4), 128.55 (s, 2 C, H3),
1
130.23 (s, 2 C, H2), 131.22 (s, 2 C, H5), 137.39 (d, JC,P = 13 Hz, 2
2
C, H6), 142.51 (d, JC,P = 26.1 Hz, 2 C, H1) ppm. 31P{1H} NMR
3
3
Scheme 1 for numbering): δ = 0.89 (dd, JH,H = 7.4, JH–P
=
(161 MHz, CDCl3): δ = –31.9 ppm.
11.6 Hz, 12 H, H9), 1.05 (d, JH,H = 6.9 Hz, 6 H, H8), 2.08 (m, 2
3
H, H10), 4.09 (sep, JH,H = 9.6 Hz, 1 H, H7), 7.01 (m, 1 H, H3),
3
Preparation of the Palladium Complexes: All palladium complexes
were prepared as reported previously; by a substitution of cyclooc-
tadiene (cod) in PdCl2 (cod) with a preferred phosphane ligand in
dichloromethane or diethyl ether, and purification by dichloro-
methane/hexane (1:2) solvent mixture if necessary.[31] The pre-
viously known palladium complexes were prepared by a similar
method. All the synthesized mononuclear Pd complexes are trans-
isomers.
7.11–7.22 (m, 1 H, H4), 7.34–7.46 (m, 2 H, H5, H6) ppm. 13C{1H}
NMR (100 MHz, CDCl3): δ = 20.35 (d, JC,P = 21.4 Hz, 4 C, C9),
2
24.24 (d, JC,P = 28.5 Hz, 2 C, C10), 25.94 (m, 2 C, C8), 30.66 (d,
1
3JC,P = 27 Hz, 1 C, C7), 125.03 (s, 1 C, C4), 125.13 (s, 1 C, C5),
125.19 (s, 1C C6), 128.92 (s, 1 C, C3), 132.22 (s, 1 C, C2), 132.25 (s,
1 C, C1) ppm. 31P{1H} NMR (161 MHz, CDCl3): δ = –7.4 ppm.
Diethyl(o-phenylphenyl)phosphane (2d): Following the general pro-
cedure described above, reactions of 1-bromo-2-biphenyl (4.701 g,
20.2 mmol), n-butyllithium (8.2 mL, 2.5 , 20.5 mmol) and chloro-
diethylphosphane (2.516 g, 20.2 mmol) yielded a bright viscous oil
after recrystallization from ethanol and purification by column
chromatography. The yield of the pure product was (4.749 g,
19.6 mmol, 97.0%). Exact mass (Micromass LCT, ESI+): 381.1768
Dichlorobis[diethyl(o-ethylphenyl)phosphane]palladium: A reaction
between diethyl(o-ethylphenyl)phosphane (0.978 g, 5 mmol) (2a)
and PdCl2(cod) (0.704 g, 2.5 mmol) in diethyl ether (30 mL) yielded
a yellow solid product after purification by column chromatog-
raphy. The yield of the pure product was (0.745 g, 1.3 mmol,
52.7%). C24H38Cl2P2Pd (565.82): calcd. C 50.94, H 6.77; found C
51.20, H 6.89. 31P{1H} NMR (161 MHz, CDCl3): δP = 11.1 ppm.
[M + H]+ (calculated for C27H26P, 381.1772). 1H NMR (200 MHz,
3
CDCl3, see Scheme 1 for numbering): δH () = 1.03 (t, JH,H
=
)
9.0 Hz, 6 H, H11) 1.46 (m, 4 H, H12), 7.21–7.44 (m, 9 H, H1–4,8–10
Dichlorobis[diisopropyl(o-isopropylphenyl)phosphane]palladium:
A
ppm. 13C{1H} NMR (100 MHz, CDCl3): δ = 9.52 (s, 2 C, C11),
reaction between 2b (0.976 g, 4.0 mmol) and PdCl2(cod) (0.581 g,
2.0 mmol) in diethyl ether (30 mL) yielded a yellow solid product
after purification by column chromatography. The yield of the pure
product was (1.072 g, 1.7 mmol, 82.5%). C30H49Cl2P2Pd (648.97):
calcd. C 55.43, H 7.60; found C 55.20, H 7.39. 31P{1H} NMR
(161 MHz, CDCl3): δP = 24.6 ppm.
19.09 (s, 2 C, C12), 126.89 (s, 1 C, C3), 127.14 (s, 1 C, C2), 127.35
(m, 2 C, C9), 127.81 (m, 1 C, C10), 128.13 (s, 2 C, C8), 128.76 (d,
1
3JC,P = 16.9 Hz, 1 C, C1), 129.20 (s, 1 C, C4), 129.84 (d, JC,P
=
23.0 Hz, 1 C, C5), 131.18 (s, 1 C, C7), 148.18 (d, 2JC,P = 30.6 Hz, 1
C, C6) ppm. 31P{1H} NMR (161 MHz, CDCl3): δ = –25.5 ppm.
Ethylbis(o-methylphenyl)phosphane (3a): Following the general pro-
cedure described above, reactions of 1-bromo-2-methylbenzene
Dichlorobis[diethyl(o-phenylphenyl)phosphane]palladium: A reaction
between 2d (0.962 g, 4.0 mmol) and PdCl2(cod) (0.580 g, 2.0 mmol)
404
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 397–407

Pd-Catalyzed Suzuki–Miyaura Cross-Coupling
in diethyl ether (30 mL) yielded a yellow solid product after purifi-
cation by column chromatography. The yield of the pure product
was (1.122 g, 1.7 mmol, 84.8%). C32H38Cl2P2Pd (661.91): calcd. C
yielded an orange solid product after purification by column
chromatography. The yield of the pure product was (1.317 g,
1.5 mmol, 81.8%). C34H44Cl4P2Pd2 (869.28): calcd. C 46.87, H
58.06, H 5.79; found C 57.88, H 5.49. 31P{1H} NMR (161 MHz, 5.09; found C 46.55, H 5.43. 31P NMR: δP = 40.2 ppm.
CDCl3): δP = 27.6 ppm.
Di-µ-chlorodichlorobis[bis(o-methylphenyl)phenylphosphane]dipalla-
Dichlorobis[ethylbis(o-methylphenyl)phosphane]palladium: A reac-
dium: A reaction between 4a (1.165 g, 4.0 mmol) and PdCl2(cod)
tion between 3a (0.955 g, 3.9 mmol) and PdCl2(cod) (0.560 g, (1.146 g, 4.0 mmol) in dichloromethane (20 mL) yielded an orange
2.0 mmol) in diethyl ether (30 mL) yielded a yellow solid product
after purification by column chromatography. The yield of the pure
product was (1.043 g, 1.6 mmol, 82.9%). C32H38Cl2P2Pd (661.91):
calcd. C 58.06, H 5.79; found C 58.01, H 5.44. 31P{1H} NMR
(161 MHz, CDCl3): δP = 20.3 ppm.
solid product after purification by column chromatography. The
yield of the pure product was (1.560 g, 1.7 mmol, 85.6%).
C40H38Cl4P2Pd2 (935.30): calcd. C 51.39, H 4.10; found C 51.55,
H 4.43. δP = 37.0 ppm.
Di-µ-chlorodichlorobis(tri-o-tolylphosphane)dipalladium: A reaction
between 4b (1.044 g, 3.4 mmol) and PdCl2(cod) (0.979 g, 3.4 mmol)
in dichloromethane (20 mL) yielded an orange solid product after
purification by column chromatography. The yield of the pure
product was (1.408 g, 1.5 mmol, 85.2%). C42H42Cl4P2Pd2 (963.35):
calcd. C 52.38, H 4.40; found C 52.11, H 4.42. 31P NMR: δP = 28.9
ppm.
Dichlorobis[dicyclohexyl(o-methylphenyl)phosphane]palladium:
A
reaction between (o-methylphenyl)dicyclohexylphosphane (2c)
(0.972 g, 3.4 mmol) and PdCl2(cod) (0.582 g, 2.0 mmol) in diethyl
ether (30 mL) yielded a yellow solid product after purification by
column chromatography. The yield of the pure product was
(1.153 g, 1.5 mmol, 88.2%). C38H60Cl2P2Pd (756.15): calcd. C
60.35, H 8.00; found C 59.88, H 8.29.31P{1H} NMR (161 MHz,
CDCl3): δP = 20.5 ppm.
Di-µ-chlorodichlorobis[bis(o-ethylphenyl)phenylphosphane]dipalla-
dium: A reaction between bis(o-methylphenyl)isopropylphosphane
4c (1.061 g, 3.3 mmol) and PdCl2(cod) (0.951 g, 3.3 mmol) in
Dichlorobis[isopropylbis(o-methylphenyl)phosphane]palladium: A re-
action between 3b (0.959 g, 3.7 mmol) and PdCl2(cod) (0.566 g, dichloromethane (20 mL) yielded an orange solid product after pu-
2.0 mmol) in diethyl ether (30 mL) yielded a yellow solid product
after purification by column chromatography. The yield of the pure
product was (1.143 g, 1.7 mmol, 91.9%). C34H44Cl2P2Pd (691.98):
rification by column chromatography. The yield of the pure product
was (1.486 g, 1.5 mmol, 90.1%). C44H46Cl4P2Pd2 (991.41): calcd. C
53.32, H 4.68; found C 53.17, H 4.35. 31P NMR: δP = 36.7 ppm.
calcd. C 59.19, H 6.43; found C 59.03, H 6.11. 31P NMR: δP
=
A General Procedure for the Suzuki–Miyaura Coupling Reactions:
A microwave pressure vessel (2–5 mL) was charged with the aryl
halogenide, phenylboronic acid, K2CO3 and with the correspond-
ing palladium complex. DMF (2.5 mL) and in some cases H2O
(0.5 mL) was added to the vessel, and the vessel was pre-stirred for
5 min. The resulting solution was warmed at 150 °C for 30–50 min
under standard irradiation mode. The reaction mixture was cooled
to room temperature, and water (30 mL) was added to the mixture.
The organic layer was separated, and the water extracted three
times with diethyl ether (30 mL). The ether extracts were combined
with the organic layer and dried with MgSO4, and the solvent was
removed in vacuo. The remaining residue was separated by column
chromatography using silica gel and dichloromethane/hexane (1:3)
mixture. Each experiment was repeated twice and the yields are
reported as an average of two measurements.
27.9 ppm.
Dichlorobis[diphenyl(2,4,5-trimethylphenyl)phosphane]palladium:
A
reaction between 4d (0.915 g, 3.0 mmol) and PdCl2(cod) (0.510 g,
1.8 mmol) in diethyl ether (30 mL) yielded a yellow solid product
after purification by column chromatography. The yield of the pure
product was (0.843 g, 1.1 mmol, 71.5%). C42H44Cl2P2Pd (788.06):
calcd. C 64.17, H 5.64; found C 63.65, H 5.44. 31P{1H} NMR
(161 MHz, CDCl3): δP = 20.4 ppm.
Dichlorobis[o-thiomethylphenylbis(o-methoxyphenyl)phosphane]pal-
ladium:
A
reaction between o-thiomethylphenylbis(o-meth-
oxyphenyl)phosphane (4e) (0.700 g, 1.9 mmol) and PdCl2(cod)
(0.516 g, 1.8 mmol) in diethyl ether (30 mL) yielded a yellow
solid product after purification by column chromatography. The
yield of the pure product was (0.662 g, 1.2 mmol, 67.4%).
C21H22Cl2O2PPdS (546.74): calcd. C 46.21, H 4.06; found C 46.00,
H 4.23. 31P{1H} NMR (161 MHz, CDCl3): δP = 54.3 ppm.
3-Methylbiphenyl: Colourless oil, (ref.[53] m.p. 4–5 °C). 1H NMR
(CDCl3): δ = 7.6–7.5 (m, 2 H), 7.45–7.35 (m, 3 H), 7.35–7.19 (m,
2 H), 7.18–7.0 (m, 2 H), 2.39 (s, 3 H) ppm. 13C{1H} NMR
(100 MHz, CDCl3): δ = 141.289, 141.168, 138.245, 128.642,
128.619, 127.948, 127.918, 127.118, 124.222, 21.50 ppm. GC-MS:
m/z = 168 [M+].
Dichlorobis[o-methoxyphenylbis(o-thiomethylphenyl)phosphane]pal-
ladium: A reaction between 4f (0.766 g, 2.0 mmol) and PdCl2(cod)
(0.518 g, 1.8 mmol) in diethyl ether (30 mL) yielded a yellow solid
product after purification by column chromatography. The yield of
the
pure
product
was
(0.687 g,
1.2 mmol,
67.9%). 3-Phenylpyridine: Yellow oil. 1H NMR (400 MHz, CDCl3): δ =
C21H22Cl2OPPdS2 (562.80): calcd. C 44.89, H 3.95; found C 44.55,
8.84–8.8 (m, 1 H), 8.57 (d, J = 3.5 Hz, 1 H), 7.83–7.8 (m, 1 H),
7.6–7.5 (m, 2 H), 7.5–7.4 (m, 2 H), 7.4–7.33 (m, 1 H), 7.33–7.25
(m, 1 H) ppm. 13C{1H} NMR (100 MHz, CDCl3): δ = 148.246,
148.108, 137.598, 136.386, 134.057, 128.851, 127.870, 126.908,
123.294 ppm. GC-MS: m/z = 155 [M+].
H 3.81. 31P{1H} NMR (161 MHz, CDCl3): δP = 57.4 ppm.
Di-µ-chlorodichlorobis[dicyclohexyl(o-methylphenyl)phosphane]di-
palladium:
A reaction between 2c (0.970 g, 3.4 mmol) and
PdCl2(cod) (1.164 g, 4.1 mmol) in dichloromethane (20 mL)
yielded an orange solid product after purification by column
chromatography. The yield of the pure product was (1.266 g,
1.35 mmol, 79.6%). C38H60Cl4P2Pd2 (933.45): calcd. C 48.79, H
2-Phenylquinoline: White solid, m.p. 81–83 °C (ref.[54] 82–84 °C). 1H
NMR (400 MHz, CDCl3): δ = 8.24–8.1 (m, 4 H), 7.87 (d, J =
8.57 Hz, 1 H), 7.82–7.75 (m, 1 H), 7.75–7.65 (m, 1 H), 7.6–7.4 (m,
6.47; found C 48.86, H 6.16. 31P{1H} NMR (161 MHz, CDCl3): 5 H) ppm. 13C{1H} NMR (100 MHz, CDCl3): δ = 157.31, 136.73,
δP = 44.3 ppm.
129.70, 129.61, 129.27, 128.81, 127.53, 127.42, 127.11, 126.24,
118.96 ppm. GC-MS: m/z = 205 [M+].
Di-µ-chlorodichlorobis[isoprophylbis(o-methylphenyl)phosphane]di-
1
palladium:
A
reaction between 3b (0.952 g, 3.7 mmol) and
2-Isopropylbiphenyl: White solid, m.p. 80 °C. H NMR (400 MHz,
PdCl2(cod) (1.130 g, 4.0 mmol) in dichloromethane (20 mL)
CDCl3): δ = 7.75–7.4 (m, 7 H), 7.3–7.4 (m, 2 H), 3.05 (sep, J =
Eur. J. Inorg. Chem. 2008, 397–407
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
405

S. Vuoti, J. Autio, M. Laitila, M. Haukka, a., J. Pursiainen
FULL PAPER
6.80 Hz, 1 H), 1.15 (d, J = 6.80 Hz, 6 H) ppm. 13C{1H} NMR
(100 MHz, CDCl3): δ = 146.286, 142.059, 141.040, 129.912,
129.273, 127.934, 127.631, 126.651, 125.485, 125.257, 29.309,
24.261 ppm. GC-MS: m/z = 196 [M+].
(m, 5 H), 7.3–7.42 (m, 4 H) ppm. 13C{1H} NMR (100 MHz,
CDCl3): δ = 21.19, 126.30, 127.22, 127.32, 127.71, 127.79, 128.00,
129.79, 130.45, 130.47, 137.09, 140.51, 140.70, 141.30, 141.65 ppm.
GC-MS: m/z = 258 [M+].
4-Methyl-o-terphenyl: White solid, m.p. 60–62 °C (ref.[55] 74–75 °C).
1H NMR (400 MHz, CDCl3): δ = 7.5–7.25 (m, 7 H), 7.25–7.06 (m,
4 H), 7.06–6.95 (m, 2 H), 2.29 (s, 3 H) ppm. 13C{1H} NMR
(100 MHz, CDCl3): δ = 141.614, 140.442, 138.454, 130.548,
129.799, 129.662, 128.540, 127.790, 127.388, 126.303, 21.04 ppm.
GC-MS: m/z = 244 [M+].
2,3-Dimethylbiphenyl: White solid, m.p. 97–99 °C. 1H NMR
(400 MHz, CDCl3): δ = 7.5–7.35 (m, 2 H), 7.35–7.25 (m, 3 H), 7.2–
7.05 (m, 3 H), 2.33 (s, 3 H) ppm. 2.15 (s, 3 H) ppm. 13C{1H}
NMR (100 MHz, CDCl3): δ = 142.560, 142.244, 137.134, 133.969,
129.385, 128.821, 127.955, 127.660, 126.580, 125.211, 20.690,
16.947 ppm. GC-MS: m/z = 182 [M+].
1
4-Cyanobiphenyl: White solid, m.p. 85–87 °C (ref.[57] 86–87 °C). H
NMR (400 MHz, CDCl3): δ = 7.37–7.5 (m, 3 H), 7.53–7.6 (m, 2
H), 7.62–7.73 (m, 4 H) ppm. 13C{1H} NMR (100 MHz, CDCl3): δ
= 110.76, 118.84, 127.10, 127.60, 128.56, 129.00, 132.47, 139.02,
145.52 ppm. GC-MS: m/z = 179 [M+].
4-Acetylbiphenyl: White solid, m.p. 122–123 °C (ref.[56] 118–
123 °C). 1H NMR (400 MHz, CDCl3): δ = 2.62 (s, 3 H), 7.35–7.50
(m, 3 H), 7.58–7.69 (m, 4 H), 7.99–8.04 (m, 2 H) ppm. 13C{1H}
NMR (100 MHz, CDCl3): δ = 26.58, 127.12, 127.17, 128.15,
128.83, 128.88, 135.74, 139.75, 145.65, 197.66 ppm. GC-MS: m/z
= 196 [M+].
1
2,4,5-Trimethylbiphenyl: Yellow oil. H NMR (400 MHz, CDCl3):
[1] A. Suzuki, J. Organomet. Chem. 1999, 576, 147.
[2] N. Miyaura, A. Suzuki, Chem. Rev. 1995, 95, 2457.
[3] J. Hassan, M. Sevignon, C. Gozzi, E. Shulz, M. Lemaire,
Chem. Rev. 2002, 102, 1359.
[4] A. Suzuki, Metal-Catalyzed Cross-Coupling Reagents (Eds.: F.
Diederich, P. J. Stang), Wiley-VCH, Weinheim, Germany, 1998,
chapter 2.
[5] A. Suzuki, Modern Arene Chemistry (Ed.: D. Astruc), Wiley-
VCH, Weinheim, 2002, pp. 53–106.
[6] S. R. Chemler, D. Trauner, S. J. Danishefsky, Angew. Chem. Int.
Ed. 2001, 40, 4544.
δ = 7.42–7.35 (m, 2 H), 7.35–7.22 (m, 3 H), 7.05–7.02 (m, 2 H),
2.22–2.28 (m, 9 H) ppm. 13C{1H} NMR (100 MHz, CDCl3): δ =
141.972, 139.402, 135.452, 133.755, 132.438, 131.695, 131.108,
129.253, 127.975, 126.497, 22.724, 19.309, 19.180 ppm. GC-MS:
m/z = 196 [M+].
2-Methoxybiphenyl: Colourless oil. 1H NMR (400 MHz, CDCl3):
δ = 3.75 (s, 3 H), 6.92–6.96 (m, 1 H), 6.97–7.20 (m, 1 H), 7.22–7.28
(m,
3 H), 7.28–7.42 (s, 2 H), 7.48–7.55 (m, 2 H) ppm.
13C{1H}NMR (100 MHz, CDCl3): δ = 55.42, 111.13, 120.75,
126.84, 127.91, 128.54, 129.48, 130.62, 130.81, 138.48, 156.37 ppm.
GC-MS: m/z = 184 [M+].
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2-Aminobiphenyl: Orange oil. 1H NMR (400 MHz, CDCl3): δ =
3.69 (s, 2 H), 6.69–6.72 (m, 1 H), 6.76–6.82 (m, 1 H), 7.08–7.15 (m,
2 H), 7.27–7.31 (m, 1 H), 7.32–7.44 (m, 4 H) ppm. 13C{1H} NMR
(100 MHz, CDCl3): δ = 115.49, 118.51, 127.05, 127.48, 128.39,
128.70, 128.98, 130.34, 139.42, 143.41 ppm. GC-MS: m/z = 169
[M+].
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1
2-Acetylbiphenyl: White solid, m.p. 52–54 °C (ref.[56] 53–56 °C). H
NMR (400 MHz, CDCl3): δ = 2.62 (s, 3 H), 7.30–7.42 (m, 1 H),
7.43–7.49 (m, 1 H), 7.59–7.64 (m, 3 H), 7.65–7.7 (s, 2 H), 8.0–8.4
(m, 2 H) ppm. 13C{1H} NMR (100 MHz, CDCl3): δ = 26.60,
127.13, 127.19, 128.17, 128.85, 128.89, 135.75, 139.76, 145.68,
197.67 ppm. GC-MS: m/z = 196 [M+].
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3Ј,5Ј-Dimethyl-2-(methylsulfanyl)biphenyl: White solid, m.p. 41–
43 °C. 1H NMR (400 MHz, CDCl3): δ = 2.29 (s, 3 H), 2.31–2.35
(m, 6 H), 6.95–6.96 (m, 1 H), 7.0–7.3 (m, 1 H), 7.05–7.3 (s, 5 H)
ppm. 13C{1H} NMR (100 MHz, CDCl3): δ = 15.65, 21.22, 124.31,
124.54, 126.93, 127.58, 129.00, 129.67, 136.94, 137.34, 140.23,
140.85 ppm. GC-MS: m/z = 228 [M+].
3Ј,5Ј-Dimethylphenyl-3-phenol: Red oil. 1H NMR (400 MHz,
CDCl3): δ = 2.30 (s, 6 H), 6.64 (s, 1 H), 6.78–6.83 (m, 1 H), 7.04–
7.06 (m, 1 H), 7.08–7.14 (m, 4 H), 7.18–7.25 (m, 1 H) ppm.
13C{1H} NMR (100 MHz, CDCl3): δ = 21.23, 114.12, 119.53,
124.91, 128.97, 129.76, 138.08, 140.66, 143.05, 155.76, 163.49 ppm.
GC-MS: m/z = 198 (M+).
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4-(3,5-Dimethylphenyl)benzaldehyde: White solid, m.p. 49–51 °C.
1H NMR (400 MHz, CDCl3): δ = 2.37 (s, 6 H), 6.98 (s, 2 H), 7.07
(s, 1 H), 7.39–7.50 (m, 2 H), 7.57–7.63 (m, 1 H), 7.98–8.30 (m, 1
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21.23, 127.29, 127.46, 127.98, 129.65, 130.62, 133.38, 133.66,
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3,5-Dimethyl-o-terphenyl: Yellow oil. 1H NMR (400 MHz, CDCl3):
δ = 2.15 (s, 6 H), 6.72–6.75 (m, 2 H), 6.77–6.80 (m, 1 H), 7.08–7.20
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Received: July 5, 2007
Published Online: November 20, 2007
Eur. J. Inorg. Chem. 2008, 397–407
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
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