Preparation of anionic phosphine ligands in situ for the palladium-catalyzed Buchwald/Hartwig amination reactions of aryl halides

Article abstract of DOI:10.1016/j.jorganchem.2010.04.005

2-Phenylindenyl phosphine ligand can be changed into anionic phosphine ligand in situ and utilized in the palladium-catalyzed Buchwald/Hartwig amination reactions in DME, providing good to excellent yields of amination products from aryl chlorides, bromides and iodides. ³¹P NMR studies show that the resonance for the anionic phosphine appeared between those of the (2-phenylindenyl)-dicyclohexyl phosphonium salt and (2-phenylindenyl)dicyclohexylphosphine. The calculated results were consistent with the experimental results.

Full text of DOI:10.1016/j.jorganchem.2010.04.005

Journal of Organometallic Chemistry 695 (2010) 1768e1775
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Preparation of anionic phosphine ligands in situ for the palladium-catalyzed
Buchwald/Hartwig amination reactions of aryl halides
,
a
a
b
b
a
b
Lei Chen a, Guang-Ao Yu a , Fang Li , Xiaolei Zhu , Bei Zhang , Rui Guo , Xiaozhi Li , Qihua Yang ,
*
Shan Jin a, Chenchen Liu a, Sheng-Hua Liu a
,
*
a Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, People’s Republic of China
b State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, People’s Republic of China
a r t i c l e i n f o
a b s t r a c t
Article history:
2-Phenylindenyl phosphine ligand can be changed into anionic phosphine ligand in situ and utilized in
the palladium-catalyzed Buchwald/Hartwig amination reactions in DME, providing good to excellent
yields of amination products from aryl chlorides, bromides and iodides. 31P NMR studies show that the
resonance for the anionic phosphine appeared between those of the (2-phenylindenyl)-dicyclohexyl
phosphonium salt and (2-phenylindenyl)dicyclohexylphosphine. The calculated results were consistent
with the experimental results.
Received 21 November 2009
Received in revised form
31 March 2010
Accepted 15 April 2010
Available online 21 April 2010
Ó 2010 Elsevier B.V. All rights reserved.
Keywords:
Amination
Cross-coupling
Halides
Palladium
Phosphine
1. Introduction
which all have the same basic cyclopentadienyl core, as found in
cyclopentadienyl [19], indenyl [19] or fluorenyl phosphines [20],
Palladium-catalyzed CeN bond-forming reactions have evolved
into a highly versatile and synthetically attractive technique for
targeting pharmaceutically useful intermediates [1,2]. Since the
discovery of the first catalytic amination method [3e5], efforts have
been made to increase the reaction efficacy [6e8]. Notable ligands,
such as tBu3P [9,10], Beller and co-workers’ PAP [11], Buchwald and
co-workers’ biaryl phosphines [12,13], Hartwig and co-workers’
Q-Phos and CyPF-tBu [14,15], Verkade and co-workers’ amino
phosphine [16,17], and Kwong and co-workers’ 2-indolylaryl
phosphine [18] (Fig. 1) provide excellent catalytic activity for the
cross-coupling of aryl halides (especially aryl chlorides) or aryl
mesylate/arenesulfonate.
whose Pd-complexes are excellent catalysts for various cross
coupling reactions. The sulfonated derivatives of fluorenyl phos-
phines form water soluble Pd-complexes [21e26], which showed
unprecedented catalytic activity in the cross coupling of heterocy-
clic substrates in aqueous reaction media (Fig. 2). In this paper, we
describe the development of 2-phenylindenyl dicyclohexyl-
phosphine as a novel ligand to activate the palladium catalyst for
the Buchwald/Hartwig amination reaction.
2. Results and discussion
2.1. Synthesis of (2-phenylindenyl)dicyclohexylphosphonium tetra-
Although a variety of ligands have been introduced, the rapid
assembly of structurally diverse ligand systems via simple synthetic
methods is still important for the development of versatile catalysts
for numerous applications of coupling reactions. Recently, Plenio’s
group reported a number of closely related phosphine ligands
fluoroborate (2)
2-Phenylindenyl phosphine ligand can be easily prepared from
commercially available indene and phenyl iodide (Scheme 1). 2-
Phenylindene was prepared according to the reported procedure
[27], then the straightforward deprotonation of 2-phenylindene
by nBuLi and trapping of the lithiated intermediate by Cy2PCl
afforded the corresponding phosphine 1 in good yields [28]. This
was isolated as its phosphonium salt 2 for easier storage and
handling [10].
* Corresponding authors. Tel./fax: þ86 27 67867725.
E-mail addresses: yuguang@mail.ccnu.edu.cn (G.-A. Yu), chshliu@mail.ccnu.edu.
cn (S.-H. Liu).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.04.005

L. Chen et al. / Journal of Organometallic Chemistry 695 (2010) 1768e1775
1769
t
P Bu2
t
P Bu2
t
Fe
Ph
Cy
Ph
Ph
P Bu3
n
PCy2
Ph
Fe
BuLi
P+ Cy
H
Ph
HBF4
PCy2
Cy2PCl
-
BF4
OMe
PCy2
2
PCy2
Pr
1
PCy2
MeO
Pr
N
43%
i
i
Pr
i
i
Pr
Scheme 1. Preparation of 2-phenylindene phosphonium salt 2.
i
Pr
i
Pr
2.3. Pd complex of (2-phenylindenyl)dicyclohexylphosphine in the
Buchwald/Hartwig reaction
R
N
With this 2-phenylindenyl phosphine ligand, the feasibility of
promoting CeN couplings of aryl halide was investigated. Chloro-
benzene and aniline were used as the prototypical substrates in our
reaction (Table 2). In this work the base was not screened and
tBuONa was used. Of the solvents surveyed (toluene and DME),
DME provided the best product yield (Table 2, entries 4e6).
Screening of commonly used Pd sources indicated that Pd(dba)2
and PdCl2(CH3CN)2 were suitable sources and Pd(dba)2 showed the
highest catalytic ability for the chlorobenzene coupling reaction
(Table 2, entries 4, 6e8).
N
P
R
N
R
N
N
PCy2
Fig. 1. Recent developments on effective phosphine ligands.
2.2. X-ray crystal structure of (2-phenylindenyl)
dicyclohexylphosphonium tetra-fluoroborate (2)
The scope of this reaction was then investigated under opti-
mized conditions [Pd(dba)2 (1 mol%), ligand (2 mol%), tBuONa
(1.4 equiv), 120 ꢀC], and the results are summarized in Table 3. In
most cases, the aryl chloride reacted with different amines leading
to the corresponding products in good to excellent yields. For
example, the reaction of chlorobenzene with octyl amine gave rise
to the corresponding secondary amine in 63% yield (Table 3, entry
1), while the reaction of 4-chlorotoluene or 2-chlorotoluene with
octyl amine afforded secondary amines in 55% or 36% yield,
respectively (Table 3, entries 2 and 4). Excellent yield was observed
when chlorobenzene or 2-chlorotoluene reacted with cyclic amine
The molecular structure of 2 has been confirmed by single-
crystal X-ray diffraction (Fig. 3). Selected bond lengths and
angles are listed in Table 1. In the solid state, the C(7)eC(15)
bond is in the single bond range (distance between C(7)eC(15)
is 1.501 Å) [29], while the bond distance C(7)eC(8) is 1.364 Å,
which is in the range of a carbonecarbon double bond [29]. The
distance of P(1) to the indene plane is 0.1338 Å, so the P(1)
atom is almost in the same plane as the indene, while the
distance of P(1) to the aryl ring is 2.1824 Å, which is similar to
that of 2-(dicyclohexylphosphino)-40-N,N-(dimethylamino)-
1,10-biphenyl [30]. The angle between the aryl ring and the
indenyl plane is 52.4ꢀ, the angle between the aryl ring and the C
(8)eP(1)eH(1A) plane is 58.5ꢀ. Finally, the P(1)eH(1A) bond is
directed toward the aryl ring, which is similar to the structure
of biaryl phosphines. The phosphorus lone pair is directed
toward the aryl ring [30] and, as a result, the 2/Pd catalyst can
activate the CeCl bond.
R
R
PCy2
P R
P R
PCy2
-O3S
-
SO3
Fig. 2. Phosphine ligands containing cyclopentadienyl core.
Fig. 3. Molecular structure of 2, H atoms and PFꢁ6 anion are omitted for clarity.

1770
L. Chen et al. / Journal of Organometallic Chemistry 695 (2010) 1768e1775
Table 1
The reasons for the particular efficiency of 2 as a ligand are
not clear to us. However, according to the previously reported
biaryl phosphine ligands [36], and the well-documented depro-
tonation of indene by base [19], we suggest two reasons: (1) the
structure of 2 is similar to that of the reported biaryl phosphines;
(2) the reaction of 2 with tBuONa in DME can generate the anionic
ligand in situ, and the strong electron-donor ability of the indene
anion may increase the electron density at the phosphorus and
improve the reaction rate as a result. To provide support for this
finding, we undertook a series of 31P NMR studies. When one
equivalent of tBuONa was added to a solution of phosphonium salt
in DME, the resonance for the phosphonium salt disappeared, and
Selected bond distances (Å) and angles (ꢀ) for compound 2.
C(7)eC(8)
C(7)eC(15)
C(8)eP(1)
1.364(4)
1.501(5)
1.781(3)
C(16)eP(1)
C(22)eP(1)
C(1)eC(7)
1.804(3)
1.811(3)
1.469(5)
C(8)eC(7)eC(1)
C(7)eC(8)eP(1)
C(9)eC(8)eP(1)
129.4(3)
126.9(3)
122.8(2)
C(8)eC(7)eC(15)
C(8)eP(1)eC(16)
C(8)eP(1)eC(22)
108.7(3)
109.77(15)
110.46(15)
(Table 3, entries 5 and 6). Similar results were obtained when aryl
amine was used as a replacement for morpholine (Table 3, entries
7e13).
a new signal appeared (
d
ꢁ17.17 ppm), corresponding to phos-
Besides aryl chloride, the scope of the Pd/(2-phenylindenyl)
dicyclohexylphosphine catalytic system can be extended to heter-
oaryl halide. For example, the amination of 2-chloropyridine with
morpholine in DME gave the coupled product in 94% yield, while
the reaction of 2-chloropyridine with octyl amime, aniline or ortho-
toluidine afforded the corresponding products in moderate yield
(Table 4, entries 1, 3, 4). Reactions of heteroaryl bromide with
amines were faster than reactions of heteroaryl chloride. For
instance, morpholine reacted with 2-bromopyridine in 12 h to give
the desired product in 97% yield (Table 4, entry 6). Octyl amine,
aniline and ortho-toluidine formed the coupled products in
acceptable yield in 12 h (Table 4, entries 5, 7, 8).
phine. When 4.0 equiv tBuONa was added to the phosphonium
salt in DME it gave a red solution immediately, the resonance for
the phosphonium salt disappeared, and another new signal
appeared (
d
ꢁ13.15 ppm), corresponding to anionic phosphine.
The results from the calculations were consistent with the
experimental results, since the resonance for the anionic phos-
phine appeared between that of the phosphonium salt 2 and 1
(Scheme 2, Table 7). Work is in progress in our laboratory with the
aim of demonstrating the anionic effect of this ligand on the
catalytic activity.
The reaction conditions optimized for the amination of aryl
chlorides were also effective for the amination of aryl bromides.
Generally, the rates for amination of aryl bromide were faster than
those for amination of aryl chlorides. For instance, phenyl bromide
was readily aminated with the Pd(dba)2/2 catalyst system, and the
reactions were completed in 5 h (Table 5, entries 1e4). We also
found that it was possible to efficiently couple sterically hindered
2-bromomesitylene with a variety of amines (Table 5, entries 5, 7
and 8).
Although more reactive, aryl iodides usually provide lower
yields than their bromide counterparts in such reactions
[16,31,32], the reason being that the iodide is inhibiting the
reaction by binding to a Pd(II) intermediate and forming a Pd ate
complex [33]. Only a few groups have reported an efficient
procedure for the coupling of aryl iodides with amines using
phosphine ligands [15,34,35]. Recently, Buchwald’s group reported
that reactions were smothered when DME was the solvent [33],
while we found that the Pd(dba)2/(2-phenylindenyl)dicyclohex-
ylphosphine catalyst system, in combination with DME as the
solvent, allowed phenyl iodide to couple successfully with amines
in 5 h (Table 6).
3. Conclusion
In summary, we synthesized 2-phenylindenyl phosphine ligand.
This ligand can be changed into anionic phosphine ligand in situ
and utilized in the palladium-catalyzed Buchwald/Hartwig ami-
nation reactions in DME, providing good to excellent yields of
amination products from aryl chlorides, bromides and iodides. 31P
NMR studies show that the resonance for the anionic phosphine
appeared between those of the (2-phenylindenyl)-dicyclohexyl
phosphonium salt and (2-phenylindenyl)dicyclohexylphosphine.
The calculated results were consistent with the experimental
results.
4. Experimental section
4.1. General considerations
Unless otherwise noted, all reagents were purchased from
commercial suppliers and used without purification. All Buchwald/
Hartwig amination reactions were performed in resealable screw
cap Schlenk flask (approx. 20 mL volume) in the presence of Teflon-
coated magnetic stirrer bar (3 mm ꢂ 10 mm). Toluene and DME
were distilled from sodium benzophenone ketyl under nitrogen.
Most commercially available amines were used as received. Some
amines may require distillation depending on the conditions.
tBuONa were purchased from Fluka. Silica gel (Merk, 70e230 and
230e400 mesh) was used for column chromatography. 1H NMR
spectra were recorded on a Mercury-Plus (400 MHz or 600 MHz)
spectrometer. Spectra were referenced internally to the residual
Table 2
Screen of Pd Sources and solvents for the coupling of phenyl chloride and aniline.a
1% Pd
H2N
Cl
+
2% Ligand
N
H
proton resonance in CDCl3
(TMS, 0.00 ppm) as the internal standard. Chemical shifts (
reported as part per million (ppm) in scale downfield from TMS.
13C NMR spectra were referenced to CDCl3 (
77.0 ppm, the middle
(
d
7.26 ppm), or with tetramethylsilane
Entry
Pd source
Solvent
T (ꢀC)
Time [h]
Yieldb (%)
d
d) were
1
2
3
4
5
6
7
8
Pd(dba)2
Pd(OAc)2
PdCl2(CH3CN)2
Pd(dba)2
Pd(OAc)2
PdCl2(CH3CN)2
Pd(dba)2
Toluene
Toluene
Toluene
DME
DME
DME
120
120
120
120
120
120
80
12
12
12
2
2
2
92
11
65
98
21
98
51
34
d
d
peak). 31P NMR spectra were referenced to 85% H3PO4 externally.
Coupling constants (J) were reported in Hertz (Hz). Mass spectra
(EI-MS) were recorded on a HP 5989B Mass Spectrometer. The
products described in GC yield were accorded to the authentic
samples/dodecane calibration standard from Agilent 6890 GC
system. All yields reported refer to isolated yield of compounds
estimated to be greater than 95% purity as determined by capillary
DME
DME
1
1
PdCl2(CH3CN)2
80
a
ArCl (1 mmol), aniline (1.2 mmol), Pd (1 mol%), ligand (2 mol%), tBuONa
(1.4 mmol), solvent (4 mL).
b
GC yields.

L. Chen et al. / Journal of Organometallic Chemistry 695 (2010) 1768e1775
1771
Table 3
Palladium-catalyzed amination of aryl chloride.a
1% Pd(dba)2
R'
R'
HN
R''
2% Ligand
Cl
+
N
t
BuONa
R''
DME
Entry
1
ArCl
Amine
Product
Time [h]
24
Yieldb [%]
Cl
NHoctyl
OctylNH2
OctylNH2
63
55
Me
Cl
Me
NHoctyl
2
3
24
24
MeO
Cl
MeO
NHoctyl
OctylNH2
< 5
Me
Me
NHoctyl
4
OctylNH2
24
36
Cl
Cl
O
O
N
O
HN
5
6
24
24
93
93
Me
Cl
HN
Me
N
O
Cl
H2N
N
H
7
24
96
MeO
MeO
Cl
H2N
H2N
8
15
24
24
90
91
91
N
H
Me
N
H
9
Cl
Me
Me
Me
Cl
N
H
10
H2N
Me
Me
Me
Cl
N
H
11
12
24
92
H2N
Me
Me
MeO
Me
MeO
Cl
N
15
24
91
92
H2N
H
Me
Me
13
N
H
Cl
H2N
Me
Me
a
t
ArCl (1 mmol), amine (1.2 mmol), BuONa (1.4 mmol), DME (4.0 mL), at 120 ꢀC under N2 for the indicated time.
Yield of isolated product.
b

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L. Chen et al. / Journal of Organometallic Chemistry 695 (2010) 1768e1775
Table 4
Palladium-catalyzed amination of heteroaryl halide.a
1% Pd(dba)2
R'
R'
HN
R''
2% Ligand
+
N
ArX
t
BuONa
R''
DME
Entry
1
ArX
Amine
Product
Time [h]
24
Yieldb (%)
66
Cl
Cl
NHoctyl
OctylNH2
N
N
N
O
O
HN
2
3
24
24
94
67
N
N
N
Cl
Cl
H2N
N
N
H
Me
N
N
H
4
24
57
N
H2N
Me
Br
Br
NHoctyl
5
6
OctylNH2
12
12
66
97
N
N
N
N
O
O
HN
N
Br
H2N
N
N
7
12
12
55
64
N
H
Me
Br
8
N
N
N
H
H2N
Me
a
t
ArX (1 mmol), amine (1.2 mmol), BuONa (1.4 mmol), DME (4.0 mL), at 120 ꢀC under N2 for the indicated time.
Yield of isolated product.
b
gas chromatography (GC) or 1H NMR. Compounds described in the
additional 2 h. and the LiCl that formed was removed by filtration
over a pad of Celite under Schlenk conditions. The resulting filtrate
was treated dropwise with HBF4 (48 wt% aqueous solution; 13.0 mL,
72 mmol). The organic layer was then separated from the aqueous
layer, dried over MgSO4, and filtered. Removal of the solvent
provided the white solid, which was dissolved in 10 mL of CH2Cl2.
After filtration the clear filtrate was dropped into hexane (100 mL,
vigorously stirred). The white precipitate that formed was separated
via suction filtration. Removal of the volatiles in vacuo afforded 2 as
literature were characterized by comparison of their 1H, and/or 13
NMR spectra to the previously reported data.
C
4.2. Preparation of new phosphonium salt 2
2-Phenylindene was prepared according to the method of
Nifant’ev et al [27].
(2-Phenylindenyl)dicyclohexylphosphonium tetra-fluoroborate
(2): In a 100 mL flask 2-phenylindene (1.5 g, 7.8 mmol) was dis-
solved in Et2O (50 mL) under an argon atmosphere. The mixture
was cooled to ꢁ78 ꢀC, and nBuLi (3.2 mL, 2.5 M solution in hexane,
8.0 mmol) was added. The solution was stirred for 30 min at
ꢁ78 ꢀC and then for 3 h at ambient temperature. Then the mixture
was cooled to ꢁ60 ꢀC and Cy2PCl (1.8 g, 7.8 mmol) was added. The
mixture was warmed to room temperature and stirred for
a white solid (1.6 g, 43%). 1H NMR (400 MHz, CDCl3)
d 1.21e1.87 (m,
H), 2.08 (br, 2H), 2.91 (br, 2H), 4.13 (s, 2H), 6.54 (d, 1J ¼ 484 Hz, 1H),
7.31e7.66 (m, 9H); 13C NMR (100 MHz, CDCl3)
d 24.8, 25.6, 25.7, 25.9,
27.5, 28.1, 28.9, 29.3, 121.1, 124.6, 127.3, 128.0, 128.3, 130.0, 130.4,
133.5, 141.4, 141.5, 170.1; 31P NMR (243 MHz, CDCl3):
d 11.49(d, J (P,
H) ¼ 484.0 Hz); MS (EI): 388 ([MꢁHBF4]þ, 100). Anal. Calcd for
C27H34BF4P: C, 68.08, H, 7.19; found: C, 67.96, H, 7.39.

L. Chen et al. / Journal of Organometallic Chemistry 695 (2010) 1768e1775
1773
Table 5
Palladium-catalyzed amination of aryl bromide.a
1% Pd(dba)2
R'
R'
HN
R''
2% Ligand
+
N
ArBr
t
BuONa
R''
DME
Entry
1
ArBr
Amine
Product
Time [h]
5
Yieldb (%)
Br
Br
NHoctyl
OctylNH2
65
85
O
HN
N
O
2
3
5
5
Br
H2N
N
99
99
H
Me
Br
N
H
4
5
5
H2N
Me
Me
Me
Me
Me
Me
Br
NHoctyl
Me
OctylNH2
24
64
Me
Me
Me
Me
Me
Br
N
O
O
HN
6
7
24
< 5
Me
Me
Me
Me
Me
Me
Br
H2N
N
H
24
24
78
95
Me
Me
Me
Me
Me
Me
Me
8
H2N
Br
N
H
Me
Me
a
t
ArBr (1 mmol), amine (1.2 mmol), BuONa (1.4 mmol), Pd(dba)2/ligand (1:2 ratio, mol% as indicated), DME (4.0 mL), at 120 ꢀC under N2 for the indicated time.
Yield of isolated product.
b
4.3. General procedures for reaction condition screenings
by column chromatography (hexane/ethyl acetate as eluent) to
afford the desired product.
Pd source (0.010 mmol), phosphonium salt 2 (0.020 mmol) and
tBuONa (1.4 mmol) were loaded into a Schlenk tube equipped with
a Teflon-coated magnetic stir bar. The tube was evacuated and
flushed with nitrogen for three times. Chlorobenzene (1.0 mmol),
aniline (1.2 mmol) and solvent (4.0 mL) were loaded into the tube.
The tube was then placed into a preheated oil bath (120 ꢀC or 80 ꢀC)
and stirred for the time period as indicated in Table 2. After
completion of reaction, the reaction tube was allowed to cool to
4.4. General procedures for palladium-catalyzed amination of aryl
halides
Pd(dba)2/2-catalyzed amination of aryl halides: an oven-dried
Schlenk tube equipped with a magnetic stirring bar was charged
t
with Pd(dba)2 (1 mol%), ligand 2 (2 mol%) and BuONa (1.4 mmol).
The flask was capped with a rubber septum, evacuated, and then
flushed with argon. This cycle was repeated three times. Amine
(1.2 mmol), aryl halide (1.0 mmol) and DME (4 mL) were then
successively added by syringe. The tube was stirred at room
temperature for several minutes and then placed into a preheated
room temperature. Ethyl acetate (10 ml), dodecane (200 mL,
internal standard) and water were added. The organic layer was
subjected to GC analysis. The GC yield obtained was previously
calibrated by authentic sample/dodecane calibration curve purified

1774
L. Chen et al. / Journal of Organometallic Chemistry 695 (2010) 1768e1775
Table 6
Table 8
Palladium-catalyzed amination of aryl iodide.a
Crystal data and structure refinements for 2.
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
a (Å)
C27H34BF4P
476.32
298(2)
Monoclinic
P2(1)
9.7260(5)
19.8110(8)
15.5020(6)
90
123.837(2)
90
2481.04(19)
4, 1.275
0.154
1008
1% Pd(dba)2
R'
R'
2% Ligand
+
N
ArI
HN
t
BuONa
R''
R''
DME
b (Å)
c (Å)
Entry
1
ArI
Amine
Product
Yieldb (%)
55
a
b
g
(ꢀ)
(ꢀ)
(ꢀ)
I
I
NHoctyl
OctylNH2
Volume (Å3)
Z, Dcalc (mg mꢁ3
)
Absorption coefficient (mmꢁ1
F(000)
)
O
HN
N
O
2
3
88
96
Crystal size (mm3)
0.20 ꢂ 0.10 ꢂ 0.10
1.89e25.00
11209
q
range (ꢀ)
Reflections collected
Independent reflections
3989 [Rint ¼ 0.0847]
Completeness to
q (%)
91.10
I
I
H2N
N
Maximum and minimum transmission
Data/restraints/parameters
Goodness-of-fit on F2
Final R1 and wR2 indices [I>2
R1 and wR2 indices (all data)
0.9848 and 0.9699
3989/51/338
0.811
0.0603, 0.0820
0.1348, 0.0988
H
s
(I)]
Me
N
H
4
98
H2N
Me
applied to the intensity data. The structures were solved by Pat-
terson method. The remaining non-hydrogen atoms were deter-
mined from the successive difference Fourier syntheses. All non-
hydrogen atoms were refined anisotropically except those
mentioned otherwise. The hydrogen atoms were generated
geometrically and refined with isotropic thermal parameters. The
structures were refined on F2 by full-matrix least-squares methods
using the SHELXTL-97 program package [37]. The crystal data and
structural refinements details are listed in Table 8. CCDC reference
number is 740759.
a
t
ArI (1 mmol), amine (1.2 mmol), BuONa (1.4 mmol), DME (4.0 mL), at 120 ꢀ
under N2 for 5 h.
C
b
Yield of isolated product.
Cy
Cy
Cy
P+ Cy
H
Cy
Cy
t
P
P
t
3 BuONa
BuONa
Na+
-
BF4
4.6. Calculation
In this work calculation for 31P NMR chemical shifts have been
carried out using the Gaussian 03 package. Structures have been
fully optimized at the DFT of Becke’s 3-parameter hybrid method
using the correlation function of Lee, Yang, and Parr (B3LYP) 15 at 6-
31þG(d) level. Calculations of absolute shielding constants have
been performed using the gauge-including atomic orbitals (GIAO)
perturbation method with HF and DFT methods at 6-311þG(2d, p)
level. Theoretical 31P chemical shifts were calculated using absolute
Scheme 2. Reaction of 2 with tBuONa.
oil bath (120 ꢀC) for the time period as indicated in tables. After
completion of reaction as judged by GC analysis, the reaction tube
was allowed to cool to room temperature and adsorbed onto silica
gel, and then purified by column chromatography (hexane/ethyl
acetate as eluent) to afford the desired product.
shielding constants and reference to H3PO4
(d
¼ 0.0).
4.5. X-ray diffraction studies
Acknowledgements
Crystals of 2 for X-ray diffraction were obtained by recrystalli-
zation of the pure product from dichloromethane/hexane layers.
Crystallographic data was collected on a Bruker SMART CCD area-
The authors acknowledge financial support from National
Natural Science Foundation of China (No. 20772039), the Science
Foundation of Ministry of Education for the New Teacher at the
University of China (No. 20070511006), the Natural Science Foun-
dation of Hubei Province (No. 2008CDB023)
detector diffractometer with graphite-monochromated Mo K
radiation (
a
l
¼ 0.71073 Å). Diffraction measurements were made at
room temperature. An absorption correction by SADABS was
Appendix. Supplementary material
Table 7
GIAO calculation of absolute nuclear shielding (in ppm) and chemical shifts (
d, ppm)
Characterization data for all coupling products, Crystallographic
information files (CIF) for 2. This material is available free of charge
via supplementary data. CCDC 740759 also contain crystallographic
data for 2. This material can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this article
of 31P NMR.
Entry
H3PO4
1
2
Anionic phosphine
a
s
s
HF (
DFT (
d
)
346.2 (0)
288.5 (0)
337.3 (ꢁ8.9)
370.2 (24)
292.7 (4.2)
364.2 (18)
285.8 (ꢁ2.7)
a
d
)
272.0 (ꢁ16.5)
a
d
(mol) ¼
s
(H3PO4) ꢁ
s
(mol), relative to H3PO4
(d
¼ 0.0).

L. Chen et al. / Journal of Organometallic Chemistry 695 (2010) 1768e1775
1775
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