Phosphines having a 2,3,4,5-tetraphenylphenyl moiety: Effective ligands in palladium-catalyzed transformations of aryl chlorides

Article abstract of DOI:10.1021/om060615q

Three new triarylphosphines were prepared that have a 2,3,4,5- tetraphenylphenyl (TPPh) moiety on one of the phenyl rings (at the ortho, meta, or para position) of triphenylphosphine. Among them, the ortho derivative is particularly effective to utilize unactivated aryl chlorides in three different palladiumcatalyzed reactions, i.e., Suzuki-Miyaura coupling, Mizoroki-Heck reaction, and silylation with Me₃SiSiMe₃. On the other hand, the corresponding meta and para derivatives are not effective as ligands at all in these catalytic reactions. X-ray crystal structures of Pd(0) complexes having the effective phosphines (ortho derivatives) as ligands show that η²-coordination on the TPPh moiety is general and operative to realize a highly active catalyst system.

Full text of DOI:10.1021/om060615q

Organometallics 2006, 25, 4665-4669
4665
Phosphines Having a 2,3,4,5-Tetraphenylphenyl Moiety: Effective
Ligands in Palladium-Catalyzed Transformations of Aryl Chlorides
Tetsuo Iwasawa, Tomoko Komano, Atsunori Tajima, Makoto Tokunaga, Yasushi Obora,
Tetsuaki Fujihara, and Yasushi Tsuji*
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto UniVersity,
CREST, Japan Science and Technology Agency (JST), Kyoto 615-8510, Japan, and Catalysis Research
Center, Hokkaido UniVersity, Sapporo 001-0021, Japan
ReceiVed July 9, 2006
Three new triarylphosphines were prepared that have a 2,3,4,5-tetraphenylphenyl (TPPh) moiety on
one of the phenyl rings (at the ortho, meta, or para position) of triphenylphosphine. Among them, the
ortho derivative is particularly effective to utilize unactivated aryl chlorides in three different palladium-
catalyzed reactions, i.e., Suzuki-Miyaura coupling, Mizoroki-Heck reaction, and silylation with
Me3SiSiMe3. On the other hand, the corresponding meta and para derivatives are not effective as ligands
at all in these catalytic reactions. X-ray crystal structures of Pd(0) complexes having the effective
phosphines (ortho derivatives) as ligands show that η2-coordination on the TPPh moiety is general and
operative to realize a highly active catalyst system.
Introduction
Dendrimers consisting of a 2,3,4,5-tetraphenylphenyl (TPPh)
moiety are receiving considerable attention as polyphenylene
nanomaterials due to their eminent optical and electrical
properties.1 We have recently found that the new pyridine lig-
and (1) having a TPPh moiety at the 3-position is an excel-
lent ligand in a palladium-catalyzed air oxidation of alcohols
to suppress Pd black formation and maintain catalytic activity
for a long time.2 We also reported that the new chiral di-
amine ligand (2) having a TPPh moiety realizes high selec-
tivity in kinetic resolution of axially chiral 2,2′-dihydroxy-1,1′-
biaryls by palladium-catalyzed alcoholysis.3 The rigid and
spatially spread TPPh moiety on the pyridine (1) and the di-
amine (2) ligands has a pronounced effect on these catalytic
reactions.
Phosphines are also very important ligands in homogeneous
transition metal catalysis.4 In the present study, we prepared
new triarylphosphines bearing TPPh on one of the phenyl rings
of triphenylphosphine (ortho: 3, meta: 4, para: 5). Among
them, 3 is a particularly efficient ligand to utilize unactivated
aryl chlorides5 in three different palladium-catalyzed reactions,
i.e., Suzuki-Miyaura coupling,6 Mizoroki-Heck reaction,7 and
silylation with Me3SiSiMe3.8
* To whom correspondence should be addressed. E-mail: ytsuji@
scl.kyoto-u ac.jp.
(1) (a) Watson, M. D.; Fechtenkotter, A.; Mu¨llen, K. Chem. ReV. 2001,
101, 1267-1300. (b) Berresheim, A. J.; Muller, M.; Mu¨llen, K. Chem. ReV.
1999, 99, 1747-1785, and references therein.
(2) Iwasawa, T.; Tokunaga, M.; Obora, Y.; Tsuji, Y. J. Am. Chem. Soc.
2004, 126, 6554-6555.
(3) Aoyama, H.; Tokunaga, M.; Kiyosu, J.; Iwasawa, T.; Obora, Y.; Tsuji,
Y. J. Am. Chem. Soc. 2005, 127, 10474-10475.
(4) (a) Homogeneous Catalysis with Metal Phosphine Complexes;
Results and Discussion
Pignolet, L. H., Ed.; Plenum Press: New York, 1983. (b) Homogeneous
Transition Metal Catalyzed Reactions; Moser, W. R., Slocum, D. W., Eds.;
American Chemical Society: Washington, D.C., 1992.
(5) For a review of activation of aryl chlorides, see: Littke, A. F.; Fu,
G. C. Angew. Chem., Int. Ed. 2002, 41, 4176-4211.
Novel phosphines (3, 4, and 5) were synthesized straightfor-
wardly by lithiation of the corresponding bromides followed
(6) (a) Miyaura, N.; Suzuki, A. Chem. ReV. 1995, 95, 2457-2483.
(b) Miyaura, N. In Metal-Catalyzed Cross-Coupling Reaction; de Meijere,
A., Diederich, F., Eds.; Wiley-VCH: Weinheim, 2004; Vol. 1, pp 41-
123.
(7) (a) Mizoroki, T.; Mori, K.; Ozaki, A. Bull. Chem. Soc. Jpn. 1971,
44, 581. (b) Heck, R. F.; Nolley, J. P., Jr. J. Org. Chem. 1972, 37, 2320-
2322. (c) Heck, R. F. Org. React. 1982, 27, 345-390. (d) Beletskaya, I.
P.; Cheprakov, A. V. Chem. ReV. 2000, 100, 3009-3066.
10.1021/om060615q CCC: $33.50 © 2006 American Chemical Society
Publication on Web 08/18/2006

4666 Organometallics, Vol. 25, No. 19, 2006
Iwasawa et al.
Table 1. Suzuki-Miyaura Coupling of
2-Chloro-1,3-dimethylbenzene with Phenylboronic Acid with
Various Phosphinesa
entry
phosphine
conditionsa
yield (%)b
1
2
3
4
5
6
7
8
3
A
A
A
A
A
A
B
B
B
B
B
B
B
C
C
C
C
C
C
C
92 (84)
P(t-Bu)3
PCy3
7
8
9
3
P(t-Bu)3
PCy3
7
7
8
9
3
P(t-Bu)3
PCy3
7
8
9
9
12
24
3
2
51
82
6
0
2
61
0
32
1
10
6
10
>99
50
>99
9
10
11c
12
13
14
15
16
17
18
19
20d
Figure 1. ORTEP drawing of 3 with thermal ellipsoids at the 50%
probability level.
by treatment with Ph2PCl. The molecular structure of 3
determined by crystallographic analysis is shown in Figure 1.9
The structure shows that the TPPh moiety spatially spreads out
and the lone pair of the phosphorus atom points to the TPPh
unit due to steric repulsion between the TPPh and the phenyl
rings on the phosphorus.
a Conditions A: aryl chloride (1.0 mmol), phenylboronic acid (1.5 mmol),
Pd2(dba)3‚CHCl3 (0.005 mmol), phosphine (0.012 mmol), KF (3 mmol),
in THF (1 mL) at 50 °C for 14 h. Conditions B: aryl chloride (0.5 mmol),
phenylboronic acid (0.75 mmol), Pd2(dba)3‚CHCl3 (0.005 mmol), phosphine
(0.02 mmol), K3PO4‚H2O (1.5 mmol), in toluene (1.7 mL) at 50 °C for 14
h. Conditions C: aryl chloride (1.0 mmol), phenylboronic acid (1.5 mmol),
Pd(OAc)2 (0.005 mmol), phosphine (0.005 mmol), K3PO4‚H2O (3 mmol),
in THF (1 mL) at room temperature for 14 h. b Determined by GC. Isolated
yield in parentheses. c At 110 °C. d For 32 h.
The triarylphosphines 3, 4, and 5 were employed as a ligand
in Suzuki-Miyaura coupling of an unactivated aryl chloride,
4-chlorotoluene, with phenylboronic acid in the presence of
Pd2(dba)3‚CHCl3 (dba ) dibenzylideneacetone, 1,5-diphenyl-
1,4-pentadien-3-one) and KF in THF at 50 °C (eq 1). In the
reaction, 3 as the ligand smoothly afforded 4-methylbiphenyl
in 97% yield. In contrast, the use of the corresponding meta
(4) and para (5) derivatives gave no coupling adduct and the
starting materials remained unchanged. Without a phosphine
ligand or with a phosphine such as diphenyl(2-phenylphenyl)-
phosphine (6),10 PPh3, tri(o-tolyl)phosphine, tris(2,4,6-trimeth-
ylphenyl)phosphine, tri(4-methoxyphenyl)phosphine, 1,2-bis-
(diphenylphosphino)ethane (DPPE), and (()-2,2′-bis(diphen-
ylphosphino)-1,1′-binaphthyl (BINAP), almost no conversions
of 4-chlorotoluene were observed in eq 1. Thus, 3 is a very
unique phosphine to activate and utilize unactivated aryl chlor-
ides5 in the coupling reaction.
comparable to that of triaryl phosphines.14,15 Therefore, the
efficacy of 3 as the ligand was compared with these representa-
tive phosphines of high basicity using 2-chloro-1,3-dimethyl-
benzene as a hindered substrate. It is well-known that the
Suzuki-Miyaura coupling reaction is considerably affected by
the nature of the catalyst precursor, the added base, and
solvent.6,11-13 Therefore, the efficacy of the phosphine ligands
was examined under three different reaction conditions (Table
1): conditions A (Pd2(dba)3-KF in THF at 50 °C),11a conditions
B (Pd2(dba)3-K3PO4 in toluene at 50 °C),12,13b and conditions
C (Pd(OAc)2-K3PO4 in THF at room temperature).13a Under
conditions A, 3 afforded the product in 92% yield (entry 1),
although the basic phosphine ligands such as P(t-Bu)3, PCy3,
(11) (a) Littke, A. F.; Dai, C.; Fu, G. C. J. Am. Chem. Soc. 2000, 122,
4020-4028. (b) Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. 1998, 37,
3387-3388.
Very basic and bulky phosphines such as P(t-Bu)3,11 PCy3
(Cy ) cyclohexyl),11 7,12 and 813 have been reported as efficient
ligands in Suzuki-Miyaura coupling of unactivated aryl chlo-
rides. However, the basicity of 3 is not very high and is
(12) Wolfe, J. P.; Singer, R. A.; Yang, B. H.; Buchwald, S. L. J. Am.
Chem. Soc. 1999, 121, 9550-9561.
(13) (a) Barder, T. E.; Walker, S. D.; Martinelli, J. R.; Buchwald, S. L.
J. Am. Chem. Soc. 2005, 127, 4685-4696. (b) Walker, S. D.; Barder, T.
E.; Martinelli, J. R.; Buchwald, S. L. Angew. Chem., Int. Ed. 2004, 43,
1871-1876.
(8) (a) Matsumoto, H.; Yoshihiro, K.; Nagashima, S.; Watanabe, H.;
Nagai, Y. J. Organomet. Chem. 1977, 128, 409-413. (b) Matsumoto, H.;
Nagashima, S.; Yoshihiro, K.; Nagai, Y. J. Organomet. Chem. 1975, 85,
C1-C3. (c) Matsumoto, H.; Shono, K.; Nagai, Y. J. Organomet. Chem.
1981, 208, 145-152. (d) Rich, J. D. J. Am. Chem. Soc. 1989, 111, 5886-
5893.
(14) (a) Basicity of phosphines is evaluated by theoretical calculation
(B3LYP/6-31G(d,p) level) of the molecular electrostatic potential minimum
(Vmin) according to the method of Koga et al.14b Vmin values (in kcal/mol)
for the representative phosphines are as follows. 3: -34.0, 4: -35.3, 5:
-35.6, 6: -34.8, PPh3: -34.8, P(t-Bu)3: -45.2, PCy3: -43.9, 7: -47.4, 8:
-47.3, 9: -44.9. More negative Vmin values indicate more basic phosphines.
(b) Suresh, C. H.; Koga, N. Inorg. Chem. 2002, 41, 1573-1578.
(15) (a) So far several phosphines13a,15b,c having comparable basicity to
triarylphosphines were found to be effective in Suzuki-Miyaura coupling
of unactivated aryl chlorides. (b) Liu, S.; Choi, M. J.; Fu, G. C. Chem.
Commun. 2001, 2408-2409. (c) Yin, J.; Rainka, M. P.; Zhang, X.;
Buchwald, S. L. J. Am. Chem. Soc. 2002, 124, 1162-1163.
(9) Crystal data of 3: C48H35P, triclinic, space group P1h (#2), colorless,
a ) 12.414(3) Å, b ) 12.782(3) Å, c ) 23.901(5) Å, R ) 76.984(6)°, â )
71.554(6)°, γ ) 86.812(6)°, V ) 3504.6(13) Å3, Z ) 4, T ) -160 °C,
dcalcd ) 1.218 g cm-3, µ(Mo, KR) ) 1.12 cm-1, observed reflections 30 955
(I > 3σ(I)), R1 ) 0.0625, wR2 ) 0.165, GOF ) 1.540.
(10) Baillie, C.; Chen, W.; Xiao, J. Tetrahedron Lett. 2001, 42, 9085-
9088.

Phosphines HaVing a 2,3,4,5-Tetraphenylphenyl Moiety
Organometallics, Vol. 25, No. 19, 2006 4667
Table 2. Suzuki-Miyaura Coupling of Various Aryl Chlorides with Arylboronic Acidsa
a Conditions: aryl chloride (1.0 mmol), arylboronic acid (1.5 mmol), KF (3 mmol), cat. Pd2(dba)3‚CHCl3 (3.5 × 10-4 to 5 × 10-3 mmol), 3 (8.4 × 10-4
to 1.2 × 10-2 mol: P/Pd ) 1.2), in THF (1 mL). b Isolated yields. c 4-Chloroacetophenone (1.4 mmol).
Table 3. Mizoroki-Heck Reaction of Chlorobenzene with
7, and 8 afforded the product in only low yields (2-24%, entries
2-5). Similar results were obtained under conditions B: 3
provided the product in 82% yield (entry 7), while the yields
were low (0-6%) with the representative basic phosphine
ligands (entries 8-10 and 12). With 7 as the ligand, the yield
was 2% at 50 °C (entry 10), and the product was obtained in
61% yield when the reaction temperature was raised to 110 °C
(entry 11). In contrast, under conditions C, 3 (the product in
1% yield, entry 14) as well as P(t-Bu)3, PCy3, and 7 (the product
in 6-10% yields, entries 15-17) were not effective ligands at
all, but 8 afforded the product almost quantitatively (entry 18).
Even 3 is a very poor ligand under conditions C. Tuning the
basicity of the phosphine might affect the efficiency. So, the
corresponding dicyclohexyl derivative (9) was prepared and was
used as the ligand in the catalytic reaction. As expected, 9 is
much more basic than 3 (Vmin14 ) -44.9 kcal/mol for 9, -34.0
kcal/mol for 3). X-ray crystal structure analysis indicates that 9
has a very similar structure in which the lone pair on the
phosphorus atom points to the TPPh moiety (see Figure S1 in
the Supporting Information). Under conditions A, 9 (the product
in 51% yield, entry 6) was not as effective as 3 (entry 1). Under
conditions B, 9 (the product in 32% yield, entry 13) was not a
better ligand than 3 either (entry 7). However under conditions
C, 9 turned out to be a superior ligand to 3, affording the product
in 50% yield in 14 h (entry 19) and >99% yield in 32 h (entry
20). Thus, the phosphines 3 and 9, having a TPPh moiety, are
quite effective and unique ligands in the Suzuki-Miyaura
coupling of unactivated aryl chlorides.
Methyl Acrylate with Various Phosphinesa
entry
phosphine
yield (%)b
1
2
3
3
4
5
>99 (98)
0
0
4
6
2
5
PPh3
1
6
7
P(t-Bu)3
PCy3
63
0
8
9
10
7
8
9
13
10
24
a Conditions: chlorobenzene (1 mmol), methyl acrylate (2 mmol),
Pd2(dba)3‚CHCl3 (0.015 mmol), phosphine (0.06 mmol), Cs2CO3 (1.1 mmol)
in 1,4-dioxane (1 mL), under reflux for 22 h. b Determined by GC. Isolated
yield in parentheses.
reaction with Me3SiSiMe3,8 were carried out. In the Mizoroki-
Heck reaction of chlorobenzene with methyl acrylate (Table 3),
the ortho derivative (3) was highly effective as the ligand to
afford the desired product in >99% yield (entry 1), while the
meta (4) and the para (5) derivatives did not afford the product
at all and chlorobenzene remained unchanged (entries 2 and
3). With other triarylphosphines such as 6 and PPh3, conversions
of chlorobenzene were very low (entries 4 and 5). As for the
basic phosphines, P(t-Bu)3 as the ligand showed substantial
catalytic activity (the product in 63% yield, entry 6), as reported
by Fu et al.16 However, PCy3, 7, and 8 gave the product in
only 0%, 13%, and 10% yields, respectively (entries 7-9). The
dicyclohexylphosphine 9 was not as effective as 3 and provided
the product in 24% yield (entry 10).
Several aryl chlorides and arylboronic acids were cross-
coupled efficiently with 3 as the ligand (Table 2). The reaction
between 2-chloro-1,3-dimethylbenzene and 2-methylphenyl-
boronic acid successfully proceeded to afford 2,2′,6-trimethyl-
biphenyl in 93% yield (entry 1). 2-Chloroanisole provided the
desired biphenyl in 97% yield (entry 2). Activated aryl chlorides
with electron-withdrawing substituents gave the products in high
yields with a low catalyst loading (0.05 mol %) (entry 3) or at
room temperature (entry 4).
In the silylation of chlorobenzene with Me3SiSiMe3 (Table
4), the ortho derivative (3) afforded the silylated product in 77%
yield (entry 1), while again meta (4) and para (5) derivatives
were almost ineffective as the ligand (entries 2 and 3). With
To further examine the efficacy of the phosphine ligands, 3
and 9, having a TPPh moiety, two more palladium-catalyzed
reactions, the Mizoroki-Heck reaction7 and the silylation
(16) (a) Littke, A. F.; Fu. G. C. J. Am. Chem. Soc. 2001, 123, 6989-
7000. (b) Littke, A. F.; Fu, G. C. J. Org. Chem. 1999, 64, 10-11.

4668 Organometallics, Vol. 25, No. 19, 2006
Iwasawa et al.
Table 4. Palladium-Catalyzed Silylation of Chlorobenzene
with Hexamethyldisilane with Various Phosphinesa
entry
phosphine
yield (%)b
1
2
3
4
77
2
3
5
0
4
6
1
5
PPh3
1
6
7
8
9
P(t-Bu)3
PCy3
7
8
9
62
12
55
24
94
Figure 2. ORTEP drawing of 11 with thermal ellipsoids at the
10
50% probability level.
a Conditions: chlorobenzene (0.5 mmol), hexamethyldisilane (2 mmol),
Pd2(dba)3‚CHCl3 (0.0075 mmol), phosphine (0.03 mmol; P/Pd ) 2), LiF
(0.55 mmol), at 110 °C for 48 h. b Determined by GC.
dination of one of the phenyl rings of the TPPh moiety, as
clearly shown by the short Pd-C7 and Pd-C12 distances of
2.376(3) and 2.361(3) Å, respectively. The phenyl ring contain-
ing C(7) and C(12) considerably deformed from planarity: the
mean deviations from the plane of the corresponding phenyl
rings are 0.0384 Å for 11 (Figure 2) and 0.0049 Å for 3 (Figure
1). The η2-coordination stabilizes the mono(phosphine) species
by adding two more electrons to the Pd(0) center. With the
dicyclohexylphosphine 9, similar clean reaction with Pd(dba)2
(P/Pd ) 1) afforded the Pd(9)(dba) complex, 12 (31P resonance
at 30.3 ppm), in 99% NMR yield. The reaction of 12 with maleic
anhydride similarly provided the Pd(9)(maleic anhydride)
complex, 13 (31P resonance at 38.0 ppm), in 99% NMR yield.
The X-ray crystal structure of 13 is very similar to that of 11,
with the same intramolecular η2-coordination (see Figure S2 in
the Supporting Information).
Very recently, Buchwald et al. reported less common
η1-coordination13 with a Pd(0) complex having 8 as a ligand.
The X-ray crystal structures of 11 and 13 (Figures 2 and S2)
indicate that the more common η2-coordination15c is a very char-
acteristic feature of the ligands 3 and 9, having a TPPh moiety.
The η2-coordination is only possible with the ortho derivatives
3 and 9. With the meta (4) and the para (5) derivatives, such
η2-coordination and the resulting high catalytic activity can-
not be expected. In the catalytic reactions, the intramolecular
η2-coordination stabilizes the mono-phosphine species, but the
η2-ligand would be labile and dissociate to generate highly un-
saturated Pd(0) species having 3 or 9, which must be the
responsible species for the high catalytic activities in the three
different palladium-catalyzed reactions of unactivated aryl
chlorides (Tables 1-4). These observations clearly indicate that
the ηn-coordination (n ) 2 or 1) facilitated by properly designed
ligand such as 3, 9, and 8 is very general and operative to realize
highly active catalyst systems.
triarylphosphines such as 6 and PPh3, conversions of chloroben-
zene were very low (entries 4 and 5). Basic phosphines such as
P(t-Bu)3 and 7 could be used in the reaction to afford the product
in 62% (entry 6) and 55% (entry 8) yields, respectively.
However, PCy3 and 8 were not effective as the ligand, providing
the product only in 12% (entry 7) and 24% (entry 9) yields,
respectively. Noteworthy is that in the silylation reaction 9 was
a more effective ligand than 3 to afford the product in 94%
yield (entry 10).
In these palladium-catalyzed reactions using unactivated aryl
chlorides as substrates (Tables 1-4), the phosphine ligands 3
and 9, having a TPPh moiety at the ortho position, realize high
catalytic activity. To elucidate why 3 is a very efficient ligand
in these catalytic reactions, stoichiometric reactions of 3 with
17
Pd(dba)2 were carried out at 50 °C in THF-d8 for 1 h at the
three P/Pd ratios of 1, 2, and 3. The reactions were monitored
by 31P NMR. At P/Pd ) 1, the 31P resonance of free
(uncoordinated) 3 at -12.7 ppm almost disappeared in 1 h and
a new complex (10) appeared at 18.2 ppm. With P/Pd ) 2 and
3, the complex 10 remained intact, and with an increase in the
P/Pd ratio the peak intensity of the free 3 at -12.7 ppm
increased. These results may suggest that complex 10 would
be a mono(phosphine)palladium species with a composition such
as Pd(3)(dba). However, all trials to isolate complex 10 were
unsuccessful, because the complex was rather unstable and
decomposed during the isolation procedures.
After several trials, we successfully stabilized the complex
by substituting the dba ligand with maleic anhydride. First, the
reaction of 3 with Pd(dba)2 at 50 °C in THF-d8 for 1 h was
carried out at P/Pd ) 1, which afforded complex 10 (31P
resonance at 18.1 ppm) in 88% NMR yield. Then, to that
reaction mixture at room temperature was added 1.2 equiv of
maleic anhydride. The reaction was very clean. In 17 h, complex
10 disappeared and a new complex, 11, having a 31P reso-
nance at 24.7 ppm, was given in 98% NMR yield. By
concentrating the solution and adding pentane to it, single
crystals of complex 11 suitable for X-ray crystal analysis were
successfully obtained.
Experimental Section
Preparation of 3. To a dry and degassed solution of 2′-bromo-
2,3,4,5-tetraphenylbiphenyl19 (1.08 g, 2 mmol) in THF (24 mL) at
-78 °C was added n-butyllithium (2.2 mmol, 1.59 M in hexane)
dropwise over 2 min, and the resulting yellow suspension was
stirred vigorously at -50 °C for 2.5 h. To the suspension at -78
°C was added chlorodiphenylphosphine (485 mg, 2.2 mmol)
The molecular structure of 11 is shown in Figure 2.18 Selected
distances and angles are listed in Table 5. Complex 11 bears
only the phosphine 3 and maleic anhydride as the ligands. The
most characteristic feature of 11 is the intramolecular η2-coor-
(18) Crystal data of 11‚(C4H8O): C56H45O4PPd, triclinic, space group
P1h (#2), pale yellow, a ) 9.977(9) Å, b ) 12.097(8) Å, c ) 18.97(2) Å,
R )85.60(6)°, â )83.22(7)°, γ )76.05(3)°, V )2203.3(36) Å3, Z ) 2, T
) -160 °C, dcalcd ) 1.386 g cm-3, µ(Mo KR) ) 5.06 cm-1, observed
reflections 8318 (I > 3σ(I)), R1 ) 0.0520, wR2 ) 0.1540, GOF ) 1.027.
(19) For a preparation method of this new compound, see the Supporting
Information.
(17) In the catalytic reactions (Tables 1-4), Pd(dba)2 as a catalyst
precursor showed the same catalytic activity as Pd2(dba)3‚CHCl3. Therefore,
in the stoichiometric reaction, Pd(dba)2 was employed in place of Pd2(dba)3‚
CHCl3 since Pd(dba)2 provided cleaner reactions.

Phosphines HaVing a 2,3,4,5-Tetraphenylphenyl Moiety
Organometallics, Vol. 25, No. 19, 2006 4669
Table 5. Selected Bond Lengths and Angles of 11
was isolated in 84% yield by column chromatography (silica gel
with hexane as an eluent). 1H NMR (400 MHz, CDCl3): δ 7.45-
7.41 (m, 2H), 7.36-7.32 (m, 1H), 7.19-7.11 (m, 5H), 2.04 (s,
6H). 13C NMR (100 MHz, CDCl3): δ 142.3, 141.6, 136.5, 129.5,
128.9, 127.8, 127.5, 127.1, 21.3. MS (EI) m/z: 182 (M+), 167.
length (Å)
angle (deg)
Pd-P1
Pd-C7
Pd-C12
Pd-C50
Pd-C51
2.312(1)
2.376(3)
2.361(3)
2.104(4)
2.135(4)
P-Pd-C7
82.65(9)
102.89(9)
115.4(1)
153.9(1)
82.65(9)
P-Pd-C12
P-Pd-C50
P-Pd-C51
P-Pd-C7
Procedure for the Mizoroki-Heck Reaction. Cs2CO3 (385 mg,
1.1 mmol) was dried in vacuo in a 20 mL Schlenk flask with heating
(heat gun) for 1 min. Then, the flask was charged with Pd2(dba)3‚
CHCl3 (16 mg, 0.015 mmol) and the phosphine 3 (39 mg, 0.06
mmol), and the whole system was evacuated and backfilled with
argon three times. Under an argon atmosphere, chlorobenzene (1
M in 1,4-diaxane, 1 mL) and methyl acrylate (172 mg, 2 mmol)
were added. The resulting suspension was stirred at room temper-
ature for 10 min. The reaction was carried out under reflux (oil
bath at 110 °C) for 22 h. After the reaction, the reaction mixture
was diluted with diethyl ether (15 mL) and filtered. GC analysis
with tridecane (37 mg, 0.20 mmol) as an internal standard showed
that methyl trans-cinnamate was obtained in >99% yield. The
product was isolated in 98% yield (159 mg) by column chroma-
tography (silica gel with EtOAc/hexane ) 2/98 as an eluent), and
dropwise over 3 min. The reaction mixture was allowed to warm
to room temperature in 2 h with stirring. The solvent and all the
volatiles were thoroughly removed under vacuum. To the residue
were added chloroform (100 mL) and water (40 mL), and the whole
solution was shaken vigorously in a separatory funnel. The separated
organic layer was washed with water (40 mL), then brine (40 mL),
and dried over Na2SO4. The solution was filtered and concentrated
in vacuo to afford a crude product as viscous materials. The crude
product was dissolved in chloroform (6 mL) and precipitated by
pouring the solution into methanol (55 mL). A white powder was
collected and dried in vacuo. Recrystallization from degassed
propionitrile (10 mL) under an argon atmosphere afforded pure
product as colorless crystals in 45% yield (579 mg). 1H NMR (400
MHz, CDCl3): δ 7.34-7.23 (m, 9H), 7.20-6.81 (m, 24H), 6.66-
6.64 (m, 2H). 13C NMR (150 MHz, CDCl3): δ 147.6 (d, JCP ) 32
Hz), 141.6, 141.3, 140.4, 140.11, 140.08, 140.0 (d, JCP ) 6.3 Hz),
139.4, 139.23, 139.21, 138.5 (d, JCP ) 14 Hz), 137.2 (d, JCP ) 13
Hz), 136.4 (d, JCP ) 12 Hz), 134.3 (d, JCP ) 21 Hz), 133.6 (d, JCP
) 1.7 Hz), 133.0 (d, JCP ) 18 Hz), 132.3 (d, Jcp ) 3.0 Hz), 131.7,
1
its H NMR, GC, and TLC were identical to an authentic sample
from Wako Pure Chemical.
Procedure for Silylation of Chlorobenzene with Hexameth-
yldisilane. LiF (14 mg, 0.55 mmol) was dried in vacuo in a 20 mL
Schlenk flask with heating (heat gun) for 1 min. Then, the flask
was charged with Pd2(dba)3‚CHCl3 (7.8 mg, 0.0075 mmol) and the
phosphine 3 (19 mg, 0.03 mmol), and the whole system was
evacuated and backfilled with argon three times. Under an argon
atmosphere, hexamethyldisilane (293 mg, 2 mmol) and chloroben-
zene (56 mg, 0.5 mmol) were added, and the resulting suspension
was stirred at room temperature for 10 min. The reaction was carried
out at 110 °C for 48 h. After the reaction, the reaction mixture was
diluted with ether (15 mL) and filtered. GC analysis with tridecane
(18 mg, 0.10 mmol) as an internal standard showed that phenyl-
trimethylsilane was obtained in 77% yield. The product was isolated
by distillation in 33% yield as a colorless oil, and its 13C NMR
and GC were identical to an authentic material from Aldrich.
131.5, 131.4, 130.9 (d, Jcp ) 5.6 Hz), 129.8, 128.5, 128.4 (d, Jcp
)
7.4 Hz), 128.2 (d, Jcp ) 5.6 Hz), 127.9, 127.8, 127.2, 127.0, 126.9,
126.8, 126.6, 126.4, 125.58, 125.54, 125.48, 125.2. 31P NMR (240
MHz, CDCl3): δ -12.4. FD-MS m/z: 642 (100%, M+). Anal. Calcd
for C48H35P: C, 89.69; H, 5.49. Found: C, 89.40; H, 5.49.
Procedure for Suzuki-Miyaura Coupling (Table 1, entry 1).
KF (174 mg, 3 mmol) was dried in vacuo in a 20 mL Schlenk
flask with heating (heat gun) for 1 min. Then, phenylboronic acid
(183 mg, 1.5 mmol), Pd2(dba)3‚CHCl3 (5.2 mg, 0.005 mmol), and
the phosphine 3 (7.7 mg, 0.012 mmol) were added to the flask,
and the whole system was evacuated and backfilled with argon
three times. Under an argon atmosphere, 2-chloro-1,3-dimethyl-
benzene (1 M in THF, 1 mL) was added, and the resulting suspen-
sion was stirred at room temperature for 10 min. The reaction was
carried out at 50 °C for 14 h. After the reaction, the reaction mixture
was diluted with ethyl acetate (15 mL) and filtered. GC analysis
with an internal standard, tridecane (39 mg, 0.21 mmol), showed
that 2,6-dimethylbiphenyl12 was obtained in 92% yield. The product
Supporting Information Available: Experimental details,
characterization of new compounds, and X-ray crystal structures
of 9 and 13. This material is available free of charge via the Internet
at http://pubs.acs.org.
OM060615Q