Asymmetric synthesis of new diphosphines and pyridylphosphines via a kinetic resolution process promoted and controlled by a chiral palladacycle

Article abstract of DOI:10.1021/om100358g

A chiral palladacycle has been used successfully to promote the asymmetric hydrophosphination reactions between the racemic secondary phosphine ethylphenylphosphine and (E)/(Z)-diphenyl-1-propenylphosphine or 2-vinylpyridine in high regio-and stereoselectivities under mild conditions. Hydrophosphination of (E)-diphenyl-1-propenylphosphine with ethylphenylphosphine gave the asymmetric diphosphine chelate containing one stereogenic phosphorus donor with the R absolute configuration and one neighboring chiral S-carbon center as the major product in 60% yield. Using the same chiral metal template, the corresponding hydrophosphination reaction with (Z)-diphenyl-1-propenylphosphine gave the diastereomeric diphosphine in 40% yield with a chiral R-carbon center, but the controlled formation of the R-phosphorus configuration was not affected by the different stereochemistry in the carbon chain. A pair of separable diastereomeric palladium templates containing the naphthylamine auxiliary and the enantiomeric forms of (R_p/S_p)-[1-ethylphenylphosphino- 2-(2-pyridine)]ethane were also generated in the ratio 1.5:1 via hydrophosphination of 2-vinylpyridine with ethylphenylphosphine. The optically pure diphosphine ligands and P, N ligands could be stereospecifically liberated from the template complexes. The coordination chemistry and the absolute stereochemistry of the template complexes and dichloro complexes were determined by X-ray crystallography.

Full text of DOI:10.1021/om100358g

3374 Organometallics 2010, 29, 3374–3386
DOI: 10.1021/om100358g
Asymmetric Synthesis of New Diphosphines and Pyridylphosphines
via a Kinetic Resolution Process Promoted and Controlled by a
Chiral Palladacycle
Shuli Chen,† Joseph Kok-Peng Ng,‡ Sumod A. Pullarkat,† Fengli Liu,† Yongxin Li,† and
Pak-Hing Leung*,†
†Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang
Technological University, Singapore 637616, and ‡New Synthesis Techniques & Applications, Institute of
Chemical & Engineering Sciences, Singapore 627833
Received April 27, 2010
A chiral palladacycle has been used successfully to promote the asymmetric hydrophosphination
reactions between the racemic secondary phosphine ethylphenylphosphine and (E)/(Z)-diphenyl-1-
propenylphosphine or 2-vinylpyridine in high regio- and stereoselectivities under mild conditions.
Hydrophosphination of (E)-diphenyl-1-propenylphosphine with ethylphenylphosphine gave the
asymmetric diphosphine chelate containing one stereogenic phosphorus donor with the R absolute
configuration and one neighboring chiral S-carbon center as the major product in 60% yield. Using
the same chiral metal template, the corresponding hydrophosphination reaction with (Z)-diphenyl-1-
propenylphosphine gave the diastereomeric diphosphine in 40% yield with a chiral R-carbon center,
but the controlled formation of the R-phosphorus configuration was not affected by the different
stereochemistry in the carbon chain. A pair of separable diastereomeric palladium templates con-
taining the naphthylamine auxiliary and the enantiomeric forms of (Rp/Sp)-[1-ethylphenylphosphino-
2-(2-pyridine)]ethane were also generated in the ratio 1.5:1 via hydrophosphination of 2-vinylpyri-
dine with ethylphenylphosphine. The optically pure diphosphine ligands and P, N ligands could be
stereospecifically liberated from the template complexes. The coordination chemistry and the
absolute stereochemistry of the template complexes and dichloro complexes were determined by
X-ray crystallography.
Introduction
C-stereogenic centers, associated with transition metals,
have been proved excellent catalysts for asymmetric hydro-
genation, asymmetric hydroformylation, asymmetric hydro-
silylation, and asymmetric carbon-carbon bond formation
reactions with high enantioselectivity.1 However, due to the
lack of a natural pool of chirality together with configura-
tional instability of the phosphorus stereocenters at high
temperatures, only a few diphosphines containing P- and
C-stereogenic centers have been reported via the asymmetric
synthesis.3-5
In recent decades chiral phosphines have attracted con-
siderable interest, as they are important ligands in asymmet-
ric transition metal catalysis and synthesis.1,2 P-Stereogenic
phosphine ligands can generate an asymmetric environment
in close proximity to the metal center, thus enhancing the en-
antioselectivity of the metal-catalyzed asymmetric reaction,
which makes them more attractive ligands in asymmetric
synthesis. Diphosphines bearing P-stereogenic or P- and
Chiral pyridylphosphine ligands, which possess a combi-
nation of soft π-acceptor phosphorus and hard σ-donor
*Corresponding author. E-mail: pakhing@ntu.edu.sg.
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r
pubs.acs.org/Organometallics
Published on Web 07/02/2010
2010 American Chemical Society

Article
Organometallics, Vol. 29, No. 15, 2010 3375
nitrogen, have been widely used to prepare complexes of
different transition metals,6-14 some of which have been suc-
cessfully applied to important catalytic asymmetric react-
ions, involving asymmetric allylic substitution,8 asymmetric
hydrogenation,9 hydrosilylation,10 asymmetric hydroborat-
ion,11 asymmetric hydroformylation,12 hydration of multiple
bonds of unsaturated moieties,13 and so on. More recently,
catalytic ethane oligomerization using nickel and palladium
complexes bearing new pyridylphosphine ligands has also
been reported.14 Although a large number of pyridylphos-
phine ligands with central, axial, and planar chirality have
been synthesized, P-stereogenic pyridylphosphine ligands are
rare, with the great majority of the pyridylphosphine ligands
bearing diphenylphosphino fragments.15
residing on the carbon backbone and incorporating various
functional groups have been synthesized.5f,17 We have also
applied the methodology to the asymmetric Diels-Alder
reaction between 2-vinylpyridine and DMPP to give P-
stereogenic pyridylphosphines.18 In continuation of our
exploration of the synthesis of chiral phosphine ligands uti-
lizing these efficient auxiliaries, we herein illustrate a facile
strategy to synthesize diphosphines containing both P- and
C-stereogenic centers and P-stereogenic pyridylphosphines
via asymmetric hydrophosphination reaction promoted by
chiral cyclometalated-amine complexes involving the race-
mic secondary phosphine (()-PhEtPH and (E)/(Z)-diphenyl-
1-propenylphosphine/2-vinylpyridine.
The hydrophosphination reaction, which involves the asym-
metric addition of a P-H moiety to unsaturated carbon-
carbon bonds, is generally considered a straightforward and
efficient approach for the synthesis of chiral phosphines con-
taining different chemical functionalities.16 Our group has
previously reported the application of chiral cyclometalated-
amine complexes as efficient chiral auxiliaries to promote the
asymmetric hydrophosphination reactions involving diphe-
nylphosphine whereby a series of chiral bidentate phos-
phines bearing diphenylphosphino fragments with chirality
Results and Discussion
Asymmetric Hydrophosphination of (E)-Diphenyl-1-prope-
nylphosphine. In the absence of the metal template, there is no
reaction between (()-PhEtPH and (E)-diphenyl-1-propenyl-
phosphine under ambient conditions. As illustrated in Scheme 1,
(E)-diphenyl-1-propenylphosphine was first coordinated to (Rc)-
1 regioselectively to form the neutral complex (Rc)-2a.19 How-
ever, no reaction between complex (Rc)-2a and (()-PhEtPH was
observed. Therefore, the thermodynamically stable and kineti-
cally inert chlorine-palladium bond was cleaved by treatment
with silver perchlorate to give the kinetically labile perchlorato
complex (Rc)-3a.19,20 Complex (Rc)-3a was not isolated, but was
subsequently treated with racemic (()-PhEtPH in dichloromet-
hane at -78 °C, and the reaction mixture was allowed to warm to
room temperature. It should be noted that a ligand redistribution
process between (()-PhEtPH and (E)-diphenyl-1-propenylpho-
sphine will occur prior to the hydrophosphination reaction.17a,21
Moreover, PhEtPH is a chiral secondary phosphine, and there-
fore coordination to the metal center will generate two different
stereocenters.22,23 Therefore, in principle, hydrophosphination
of racemic (()-PhEtPH and (E)-diphenyl-1-propenylphos-
phine may generate eight possible stereoisomeric products
(Scheme 1). Complexes 4a and 4b are regioisomers with the
same absolute configurations at the newly generated stereo-
genic phosphorus and carbon centers within the diphosphine
chelate but differ in the relative regioarrangement of the
two nonequivalent phosphorus donor atoms on the metal
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3376 Organometallics, Vol. 29, No. 15, 2010
Chen et al.
Scheme 1
Figure 1. Molecular structure of complex (Rc,Sc,Rp)-4a with
50% probability ellipsoids shown.
˚
Table 1. Selected Bond Distances (A) and Angles (deg) of Com-
plex (Rc,Sc,Rp)-4a
Pd(1)-C(2)
Pd(1)-N(1) p
Pd(1)-P(1)
2.047(4)
2.134(3)
2.248 (1)
2.340(1)
1.86 (4)
1.83 (4)
1.53 (6)
1.53(6)
C(2)-Pd(1)-P(1)
N(1)-Pd(1)-P(1)
C(2)-Pd(1)-P(2)
N(1)-Pd(1)-P(2)
P(1)-Pd(1)-P(2)
C(18)-P(1)-Pd(1)
C(17)-P(2)-Pd(1)
C(17)-C(18)-P(1)
C(18)-C(17)-P(2)
95.6 (1)
175.5(1)
175.3 (1)
99.0(1)
85.0 (4)
108.8(1)
105.6 (1)
107.7(3)
107.5(3)
Pd(1)-P(2)
P(1)-C(18)
P(2)-C(17)
C(17)-C(18)
C(18)-C(19)
C(2)-Pd(1)-N(1)
80.6(2)
Scheme 2
template. Similarly, complexes 5a and 5b, 6a and 6b, 7a and
7b, and 8a and 8b are regioisomers with the same absolute
configurations at newly generated stereogenic phosphorus
and carbon centers.
Prior to purification, the 31P{1H} NMR spectrum of a
crude hydrophosphination reaction mixture in CDCl3 exhi-
bited three pairs of doublets at δ 69.7 (d, 1P, Jpp= 34.2 Hz),
30.0 (d, 1P, Jpp= 34.2 Hz); 52.3 (d, 1P, Jpp= 30.4 Hz), 44.4
(d, 1P, Jpp= 30.4 Hz); and 53.4 (d, 1P, Jpp= 30.4 Hz), 42.5
(d, 1P, Jpp= 30.4 Hz) in the ratio 9.5:1:1, respectively. After
purification by silica gel column chromatography (acetone-
hexane, 1:6), only the major product, (Rc,Sc,Rp)-4a, was
obtained. Complex (Rc,Sc,Rp)-4a was then crystallized from
dichlomethane-diethyl ether as light yellow crystals in 60%
yield (Scheme 1).
C(18) were generated, which adopt the R and S absolute
configuration, respectively, while as expected, the absolute
configuration of the stereocenters at C(11) remained un-
changed. The X-ray analysis data taken in conjunction with
the 31P{1H} coupling information also showed that this
hydrophosphination reaction is highly regioselective, as the
ethylphenylphosphino group was added preferentially to the
β-carbon of the vinylphosphines to form the five-membered
chelate ring exclusively.
The coordination chemistry and the absolute stereochem-
istry of complex (Rc,Sc,Rp)-4a were confirmed by single-
crystal X-ray diffraction analysis. The study revealed that
the expected five-membered diphosphine chelate has been
formed (Figure 1). Two new stereogenic centers at P(1) and
The geometry at palladium is distorted square planar with
angles at palladium in the ranges 80.6(2)-99.0(1)° and 175.3
(1)-175.5(1)°. The Pd-P(1) and Pd-P(2) bond distances are
˚
2.248(1) and 2.340(1) A, respectively, with the bond trans to
the carbon of the naphthylamine auxiliary being longer by

Article
Organometallics, Vol. 29, No. 15, 2010 3377
Scheme 3
Scheme 4
(d, 1P, Jpp = 21.2 Hz). It is noteworthy that the apparent
inversion of configuration that takes place at the phosphorus
stereogenic center during the liberation reaction is merely a
consequence of the Cahn-Ingold-Prelog rules.24
Figure 2. Molecular structure of complex (Sc,Rp)-8a with 50%
probability ellipsoids shown.
In order to confirm the optical purity of the liberated
ligand and to establish the identity of the hydrophosphina-
tion product, free ligand (Sc,Sp)-9a was recoordinated to the
bis(acetonitrile) complex (Rc)-10.25 When the liberated lig-
and (Sc,Sp)-9a was recomplexed to the bis(acetonitrile) com-
plex (Rc)-10 (Scheme 5), the 31P NMR spectrum of the crude
recomplexation product mixture in CDCl3 exhibited two
pairs of doublets at δ 52.3 (d, 1P, Jpp = 30.4 Hz), 44.4 (d,
1P, Jpp = 30.4 Hz) and at 69.7 (d, 1P, Jpp = 34.2 Hz), 30.0 (d,
1P, Jpp = 34.2 Hz) in the ratio 2:1, respectively. The reson-
ance signals at δ 69.7 and 30.0 are identical to those observed
for the major product, (Rc,Sc,Rp)-4a, in the original hydro-
phosphination reaction, while the signals at δ 52.3 and 44.4
match one of the minor signals seen in the original reaction
mixture and are assigned to the regioisomer of the major
product, (Rc,Sc,Rp)-4b. Interestingly, in this recomplexation
reaction, the regioisomer (Rc,Sc,Rp)-4b was the major pro-
duct, while the major product, (Rc,Sc,Rp)-4a, in the original
hydrophosphination reaction was observed to be the minor
product.
˚
Table 2. Selected Bond Distances (A) and Angles (deg) of
Complex (Sc,Rp)-8a
Pd(1)-Cl(1)
Pd(1)-Cl(2)
Pd(1)-P(1)
Pd(1)-P(2)
C(9)-C(11)
2.369(1)
2.374(1)
2.246(1)
2.234(1)
1.516(7)
C(9)-C(10)
1.509(7)
89.4(1)
85.8(1)
90.7(1)
94.1(1)
P(1)-Pd(1)-Cl(1)
P(2)-Pd(1)-P(1)
P(2)-Pd(1)-Cl(2)
Cl(1)-Pd(1)-Cl(2)
˚
0.092 A. This indicates that the two phosphorus atoms have
quite different donor abilities. In the five-membered dipho-
sphine metal chelate, the methyl substituent at the chiral
carbon center, C(18), occupies an equatorial position, which
is in accordance with our previous studies.17a,g Selected bond
distances and angles of complex (Rc,Sc,Rp)-4a are given in
Table 1.
Removal of the naphthylamine auxiliary by treatment
with strong acid is a standard method that leads to the for-
mation of the corresponding neutral dichloro palladium(II)
complex. As shown in Scheme 2, the chiral naphthylamine
auxiliary in (Rc,Sc,Rp)-4a can be removed chemoselectively
from the palladium template by treatment with concentrated
hydrochloric acid in dichloromethane. The chiral auxiliary
was recovered quantitatively from the mother liquor after
treatment with base. On the other hand, the neutral dichloro
complex (Sc,Rp)-8a was obtained efficiently as stable white
crystals in 88% yield. The 31P{1H} NMR spectrum of the
dichloro complex (Sc,Rp)-8a in CDCl3 exhibited a pair of
Hydrophosphination of (Z)-Diphenyl-1-propenylphosphine.
Hydrophosphination of (Z)-diphenyl-1-propenylphosphine
was achieved by means of a similar procedure to hydrophos-
phination of (E)-diphenyl-1-propenylphosphine (Scheme 1).
In principle, the hydrophosphination reaction between (Z)-
diphenyl-1-propenylphosphine palladium complex 3b and
racemic (()-PhEtPH may also generate the same eight pos-
sible stereoisomeric products, 4, 5, 6, and 7 as that obtained
from the reaction involving E-isomer complex 3a.
doublets at δ 80.3 (d, 1P, Jpp= 5.5 Hz) and 50.5 (d, 1P, Jpp
=
5.5 Hz). The molecular structure and absolute stereochem-
istry of (Sc,Rp)-8a was established by X-ray crystallography
(Figure 2). The selected bond lengths and angles are given in
Table 2. The absolute configurations at C(9) and P(1) are S
and R, respectively.
The optically pure diphosphine ligand (Sc,Sp)-9a can
subsequently be liberated from the dichloro complex (Sc,
Rp)-8a by treatment of the dichloro complex with saturated
aqueous potassium cyanide in dichloromethane at room
temperature for 2 h (Scheme 2). The free ligand (Sc,Sp)-9a
Prior to purification, the 31P{1H} NMR spectrum of the
crude reaction mixture in CDCl3 exhibited four pairs of
doublets at δ 67.7 (d, 1P, Jpp= 26.6 Hz), 34.9 (d, 1P, Jpp
=
26.6 Hz); 71.1 (d, 1P, Jpp =30.4Hz),34.4(d,1P,Jpp =30.4Hz);
51.7 (d, 1P, Jpp = 30.4 Hz), 45.6 (d, 1P, Jpp = 30.4 Hz); and
65.8 (d, 1P, Jpp = 30.4 Hz), 30.4 (d, 1P, Jpp = 30.4 Hz) in the
ratio of 24:13:2:1, respectively. After purification by silica gel
column chromatography (acetone-hexane, 1:6), only the
was thus obtained as a white solid in 80% yield, [R]D
=
-118.4 (c 0.2, CH2Cl2). The 31P{1H} NMR spectrum of the
free diphosphine ligand (Sc,Sp)-9a in CDCl3 exhibited a
pair of doublets at δ -0.66 (d, 1P, Jpp = 21.2 Hz) and -19.7
(24) Cahn, R. S.; Ingold, C. K.; Prelog, V. Angew. Chem., Int. Ed.
Engl. 1966, 5, 385.
(25) Chooi, S. Y. M.; Siah, S. Y.; Leung, P. H.; Mok, K. F. Inorg.
Chem. 1993, 32, 4812.

3378 Organometallics, Vol. 29, No. 15, 2010
Chen et al.
Scheme 5
Figure 3. Molecular structure of complex (Rc,Rc,Rp)-5a with
50% probability ellipsoids shown.
Figure 4. Molecular structure of complex (Rc,Rp)-8b with 50%
probability ellipsoids shown.
˚
Table 3. Selected Bond Distances (A) and Angles (deg) of Com-
plex (Rc,Rc,Rp)-5a
˚
Table 4. Selected Bond Distances (A) and Angles (deg) of Com-
plex (Rc,Rp)-8b
Pd(1)-C(2)
2.053(4)
2.139(3)
2.265(1)
2.346 (1)
1.857(4)
1.827(4)
1.526(6)
1.537(6)
79.2 (2)
C(2)-Pd(1)-P(1)
N(1)-Pd(1)-P(1)
C(2)-Pd(1)-P(2)
N(1)-Pd(1)-P(2)
P(1)-Pd(1)-P(2)
C(17)-P(1)-Pd(1)
C(19)-P(2)-Pd(1)
C(19)-C(17)-P(1)
C(17)-C(19)-P(2)
95.2 (2)
170.3(1)
177.1(1)
102.1(9)
83.9 (4)
110.5(1)
106.9(1)
109.5(3)
108.8(3)
Pd(1)-Cl(1)
Pd(1)-Cl(2)
Pd(1)-P(1)
Pd(1)-P(2)
C(13)-C(14)
2.381(2)
2.341(2)
2.249(2)
2.230(2)
1.529(10)
C(14)-C(15)
1.525(11)
93.4(1)
85.8(1)
88.9(1)
91.8(1)
Pd(1)-N(1) p
Pd(1)-P(1)
P(1)-Pd(1)-Cl(1)
P(2)-Pd(1)-P(1)
P(2)-Pd(1)-Cl(2)
Cl(1)-Pd(1)-Cl(2)
Pd(1)-P(2)
P(1)-C(17)
P(2)-C(19)
170.3(1)-177.1(1)°. The Pd-P(1) and Pd-P(2) bond dis-
tances are 2.265(1) and 2.346 (1) A, respectively, with the bond
trans to the carbon of the naphthylamine auxiliary being
C(17)-C(19)
C(17)-C(18)
C(2)-Pd(1)-N(1)
˚
˚
longer by 0.081 A. This indicates that the phosphorus atoms
major product (Rc,Rc,Rp)-5a was obtained. Complex (Rc,Rc,
Rp)-5a was crystallized from dichlomethane-diethyl ether as
light yellow crystals in 40% yield (Scheme 1)
have quite different donor abilities. Similar to diastereomeric
complex (Rc,Sc,Rp)-4a, in the five-membered diphosphine
metal chelate, the methyl substituent at the chiral carbon
center, C(17), occupies the equatorial site. Selected bond
distances and angles of complex (Rc,Rc,Rp)-5a are given in
Table 3.
As shown in Scheme 2, the chiral naphthylamine auxiliary
in (Rc,Rc,Rp)-5a can be removed chemoselectively from the
palladium template by treatment with concentrated hydro-
chloric acid in dichloromethane. The neutral dichloro com-
plex (Rc,Rp)-8b was obtained efficiently as stable white
crystals in 90% yield. The 31P{1H} NMR spectrum of the
dichloro complex (Rc,Rp)-8b in CDCl3 exhibited a pair of
The single-crystal X-ray diffraction analysis of the com-
plex (Rc,Rc,Rp)-5a revealed that the expected five-membered
diphosphine chelate had been formed (Figure 3). Two new
stereogenic centers at P(1) and C(17) were generated, both of
which adopt the R absolute configuration, while the absolute
configuration of the stereocenters at C(11) remained un-
changed. The X-ray analysis also showed that this hydro-
phosphination reaction is also highly regioselective, as the
ethylphenylphosphino group was added to the β-carbon of
the vinylphosphines to form a five-membered chelate ring
exclusively.
doublets at δ 80.8 (d, 1P, Jpp = 6.4 Hz) and 58.9 (d, 1P, Jpp =
6.4 Hz). The molecular structure and absolute stereo-
chemistry of complex (Rc,Rp)-8b was established by X-ray
The geometry at palladium is distorted square planar with
angles at palladium in the ranges 79.2 (2)-102.1(9)° and

Article
Organometallics, Vol. 29, No. 15, 2010 3379
crystallography (Figure 4), and selected bond lengths and
angles are given in Table 4. The absolute configurations at
C(9) and P(1) are both R.
By treatment of the dichloro complex (Rc,Rp)-8b with satu-
rated aqueous potassium cyanide in dichloromethane at
room temperature for 2 h, the optically pure diphosphine
ligand (Rc,Sp)-9b was liberated successfully (Scheme 4). The
free ligand (Rc,Sp)-9b was obtained as a white solid in 84%
yield, [R]D = þ92.6 (c 0.2., CH2Cl2). The 31P{1H} NMR spec-
trum of the free diphosphine ligand (Rc,Sp)-9b in CDCl3
exhibited a pair of doublets at δ -0.38 (d, 1P, Jpp = 18.4 Hz)
and -20.5 (d, 1P, Jpp = 18.4 Hz).
The optical purity of the liberated ligand (Rc,Sp)-9b
was established by subsequent recomplexation to the bis-
(acetonitrile) complex (Rc)-10 (Scheme 4). The 31P NMR
spectrum of the crude recomplexation product mixture in
CDCl3 exhibited two pairs of doublets at δ 51.7 (d, 1P, Jpp
=
Figure 5. Molecular structure of complex (Rc,Rp)-11 with 50%
probability ellipsoids shown.
30.4 Hz), 45.6 (d, 1P, Jpp = 30.4 Hz); 67.7 (d, 1P, Jpp =26.6Hz),
34.9 (d, 1P, Jpp = 26.6 Hz) in the ratio 2:1, respectively. The
resonance signals at δ 67.7 and 34.9 are identical to those
observed for the major product (Rc,Rc,Rp)-5a in the original
hydrophosphination reaction, while the signals at δ 51.7 and
45.6 match one of the minor signals seen in the original react-
ion mixture and are assigned to the major product’s regioiso-
mer, (Rc,Rc,Rp)-5b.
The recoordination step therefore proves the optical pur-
ity of the liberated ligand (Rc,Sp)-9b and also assists in identi-
fying the minor isomeric complexes generated directly from
the hydrophosphination reaction.
˚
Table 5. Selected Bond Distances (A) and Angles (deg) of
Complex (Rc,Rp)-11
Pd(1)-C(2)
Pd(1)-N(1) p
Pd(1)-N(2)
Pd(1)-P(1)
P(1)-C(17)
C(17)-C(18)
C(18)-C(19)
C(2)-Pd(1)-N(2)
C(2)-Pd(1)-N(1)
1.994(3)
2.144(3)
2.143(3)
2.241 (8)
1.829(4)
1.552(6)
1.484(6)
175.5(1)
80.9(1)
N(2)-Pd(1)-N(1)
C(2)-Pd(1)-P(1)
N(2)-Pd(1)-P(1)
N(1)-Pd(1)-P(1)
C(17)-P(1)-Pd(1)
C(19)-N(2)-Pd(1)
C(18)-C(17)-P (1)
C(19)-C(18)-C(17)
N(2)-C(19)-C(18)
95.0 (1)
93.5(1)
90.9 (8)
167.8(9)
106.5(1)
121.5(3)
113.2(2)
110.9(3)
117.5(3)
Hydrophosphination of 2-Vinylpyridine. Due to the distinct
electronic directing effects originating from the ortho-meta-
lated [(1-(dimethylamino)ethyl)-2-naphthyl- C2,N]palladium-
(II) unit,26 this hydrophosphination reaction is 100% regio-
selective, with the soft phosphorus donor exclusively taking
up the position trans to the NMe2 group in the complex. As
illustrated in Scheme 5, bis(acetonitrile) palladium(II) com-
plex (Rc)-10 was allowed to dissolve in dichloromethane first,
followed by treatment with (()-PhEtPH and 2-vinylpyridine
at -78 °C. The reaction mixture was allowed to warm to
ambient temperature and was found to be completed in 24 h.
Prior to purification, the 31P{1H} NMR spectrum of the
crude reaction mixture in CDCl3 exhibited two singlets at δ
33.0 and 34.3 in the ratio 1.5:1. Upon fractional crystalliz-
ation, the major and minor products were then crystallized
from dichlomethane-diethyl ether as white crystals in
51.5% and 31.3% yield, separately. The single-crystal X-ray
diffraction analysis revealed that the major product was com-
plex (Rc,Rp)-11, and complex (Rc,Sp)-11 is the minor product
(Scheme 5).
The single-crystal X-ray diffraction analysis of the
complex (Rc,Rp)-11 established unambiguously that the
bis(acetonitrile) palladium(II) complex (Rc)-1promoted hydro-
phosphination reaction between (()-PhEtPH and 2-vinyl-
pyridine had indeed occurred and the expected hydropho-
sphination product incorporating a six-membered P, N
chelate was formed (Figure 5). As shown in Figure 5, the
phosphorus donor atom is coordinated regiospecifically to
the metal center in the position trans to the σ-donating naph-
thylamine-N atom, while the nitrogen atom of the pyridine
binds to the position trans to the π-accepting aromatic
carbon atom of the ortho-metalated naphthylamine chelate.
A new stereogenic center adopting an R absolute configura-
tion was formed at P(1), while the absolute configuration of
the stereocenter at C(11) remained unchanged. The X-ray
analysis also showed that this hydrophosphination reaction
was highly regioselective toward the vinylic CdC bond of the
vinylpyridine, as the ethylphenylphosphino group was added
exclusively to the β-carbon of the vinylic CdC bond to form
the six-membered chelate ring exclusively. The geometry at
palladium is slightly distorted square planar with angles at
palladium in the ranges 80.9(1)-95.0(1)° and 167.8(8)-
˚
175.5(1)°. The C(17)-C(18) [1.552(6) A] and newly formed
˚
Pd(1)-N(2) [2.143(3) A] bond lengths are typical. Table 5
shows selected bond distances and angles of complex
(Rc,Rp)-11.
As shown in Figure 6, the minor product of this hydropho-
sphination reaction, complex (Rc,Sp)-11, has the same mole-
cular connectivity as the major product, complex (Rc,Rp)-11,
but differs in the absolute configuration at the newly formed
stereogenic phosphorus donor, which in this instance adopts
the S absolute configuration. The six-membered P, N chelate
has also been formed with high regioselectivity toward the
vinylic CdC bond of the vinylpyridine in complex (Rc,Sp)-
11, and the absolute configuration of the stereocenter at
C(11) remained unchanged. Selected bond lengths and bond
angles of complex (Rc,Sp)-11 are given in Table 6.
The chiral naphthylamine auxiliary in (Rc,Rp)-11 and
(Rc,Sp)-11 can be removed chemoselectively by individual
treatment with concentrated hydrochloric acid in dichloro-
methane (Scheme 6). Thus the neutral P-chiral dichloro
complexes (Rp)-12 and (Sp)-12 were obtained efficiently as
stable yellow crystals in 90% and 87% yields, respectively.
The 31P{1H} NMR spectrum of the dichloro complexes (Rp)-
12 and (Sp)-12 in CDCl3 exhibited a singlet at δ 31.1. The
(26) Chooi, S. Y. M.; Hor, T. S. A.; Leung, P. H.; Mok, K. F. Inorg.
Chem. 1992, 31, 1494.

3380 Organometallics, Vol. 29, No. 15, 2010
Chen et al.
Figure 6. Molecular structure of complex (Rc,Sp)-11 with 50%
probability ellipsoids shown.
Figure 7. Molecular structure of complex (Rp)-12 with 50%
probability ellipsoids shown.
˚
Table 6. Selected Bond Distances (A) and Angles (deg) of Com-
plex (Rc,Sp)-11
Scheme 6
Pd(1)-C(1)
1.990(4)
2.132(3)
2.176(3)
2.248(1)
1.836(4)
1.537(6)
1.498(5)
174.7(1)
80.4(1)
N(2)-Pd(1)-N(1)
C(1)-Pd(1)-P(1)
N(2)-Pd(1)-P(1)
N(1)-Pd(1)-P(1)
C(21)-P(1)-Pd(1)
C(19)-N(2)-Pd(1)
C(20)-C(21)-P (1)
C(19)-C(20)-C(21)
N(2)-C(19)-C(20)
98.7(1)
98.3(1)
83.1(9)
173.2(1)
106.3(1)
121.3(2)
113.0(3)
110.5(3)
116.7(3)
Pd(1)-N(1)
Pd(1)-N(2)
Pd(1)-P(1)
P(1)-C(21)
C(20)-C(21)
C(19)-C(20)
C(1)-Pd(1)-N(2)
C(1)-Pd(1)-N(1)
molecular structure of complex (Rp)-12 is shown in Figure 7.
The geometry at palladium is regular square planar with cis
angles ranging between 88.5(2)° and 91.2(1)°. The two Pd-
˚
Cl bond distances [2.292(2) and 2.364(1) A] differ signifi-
cantly, with the bond trans to the phosphorus being notice-
ably elongated from normal, which reflects the stronger elec-
tronic trans influence of the phosphorus relative to nitrogen.17f,27
Dichloro complex (Sp)-12 crystallized as two independent
molecules in one unit cell, and both molecules have the same
molecular connectivity as well as chirality and differ slightly
only in the bond distances and angles involved. For clarity,
only one molecule is shown Figure 8. Selected bond distances
and angles of complexes (Rp)-12 and (Sp)-12 are given in
Table 7.
The liberation of the enantiomerically pure P-chiral P, N
ligands from (Rp)-12 and (Sp)-12 was achieved by separate
treatment of the dichloro complexes with saturated aqueous
potassium cyanide in dichloromethane at room temperature
for 1 h (Scheme 6). Thus the optically pure P, N ligand (Sp)-
13 can be liberated successfully as an air-sensitive white solid
in 81% yield, [R]D = -26.1 (c 0.2, CH2Cl2). The 31P{1H}
NMR spectrum of the free ligand (Sp)-13 in CDCl3 exhibited
a singlet at δ -18.5. The enantiomeric P, N ligand, (Rp)-13,
with [R]D=þ26.1 (c 0.2, CH2Cl2), could be liberated from
dichloro complex (Sp)-12 in 82% yield (Scheme 6).
To confirm the optical purity of the liberated ligands
and as a confirmation of their structure and optical integrity,
the free ligand (Sp)-13 was recoordinated to bis(acetonitrile)
complexes (Rc)-10 and (Sc)-14 separately (Scheme 7). When
free ligand (Sp)-13 was recomplexed to bis(acetonitrile)
complex (Rc)-10, the 31P NMR spectrum of the crude
reaction mixture exhibited a sole sharp singlet at δ 33.0.
The resonance signal at δ 33.0 is identical to that recorded
for the major product (Rc,Rp)-11 in the original hydropho-
sphination reaction. When the same liberated ligand (Sp)-13
(27) Liu, X.; Mok, K. F.; Leung, P. H. Organometallics 2001, 20,
3918.

Article
Organometallics, Vol. 29, No. 15, 2010 3381
Scheme 8
Figure 8. Molecular structure of complex (Sp)-12 with 50%
probability ellipsoids shown.
Origins of the Regio- and Stereoselectivities of the Asym-
metric Hydrophosphination Reactions. Upon coordination of
a secondary phosphine to the palladium, the P-H bond is
relatively acidic and can undergo proton exchange with the
solvents to generate a small amount of phosphido complex.28
Therefore, the current chiral metal template promoted asym-
metric hydrophosphination reactions should proceed via the
simultaneous coordination of a secondary phosphine and
vinylphosphines/vinylpyridine, followed by intramolecular
nucleophilic addition of the phosphido complex to the
coordinated vinylic CdC bond to give the product.17a,f The
reason for the highly regioselective addition of the ethylphe-
nylphosphino group to the β-carbon of the CdC bond of the
vinylphosphines/vinylpyridine to form the five-membered
diphosphine or six-membered P-N chelate ring exclusively
is twofold: the coordination of the vinylphosphines/vinyl-
pyridine on the chiral palladium template leads to the polari-
zation of the vinylic CdC bond with the β-carbon of the
CdC being partially positively charged, together with the
fact that for the diphosphine chelate the five-membered
chelate ring is thermodynamically more stable than a four-
membered ring, and for the P-N chelate, according to a
Dreiding model study, the five-membered ring has much
more interchelate repulsive interactions than the six-
membered ring.19,27
˚
Table 7. Selected Bond Distances (A) and Angles (deg) of
Complexes (Rp)-12 and (Sp)-12
(Rp)-12
(Sp)-12
Pd(1)-Cl(1)
2.292(2)
2.364(1)
2.229(2)
2.047(5)
1.548(10)
1.494(13)
91.2(1)
88.5(2)
89.5(1)
91.1(1)
2.293(1)
2.370(1)
2.235(1)
2.039(3)
1.542(5)
1.500(5)
91.9(1)
88.3(1)
88.3(1)
91.9(1)
Pd(1)-Cl(2)
Pd(1)-P(1)
Pd(1)-N(1)
C(9)-C(10)
C(10)-C(11)
P(1)-Pd(1)-Cl(1)
P(1)-Pd(1)-N(1)
N(1)-Pd(1)-Cl(2)
Cl(1)-Pd(1)-Cl(2)
Scheme 7
In the current hydrophosphination reactions, the absolute
configuration at the stereogenic phosphorus center of the
major product was R. It has been well established that the
chiral naphthylamine chelate ring in (Rc)-1 is locked into the
static δ conformation both in the solid state and in solution
with the methyl substituent on the stereogenic carbon in-
variably taking up the axial position above the PdCN ring
(Scheme 8).29 The Dreiding model study reveals that steric
repulsion exists between the axial C-methyl group and the
group of the secondary phosphine located above the PdCN
ring. A correlation between the X-ray crystallography data
of the current hydrophosphination products and a Dreiding
model study indicates that the Ph group of the secondary
was treated with bis(acetonitrile) complex (Sc)-14, however,
the 31P NMR spectrum of the crude reaction mixture
showed only one singlet at δ 34.3, which matches the
resonance signal of the minor product, (Rc,Sp)-11, ob-
served in the original hydrophosphination reaction. It
has been well established that in the absence of any chiral
NMR solvent, the NMR spectra of enantiomers exhibit
identical resonance signals. Therefore, complex (Sc,Rp)-15
should be the enantiomer of the minor product in the
original hydrophosphination reaction product (Rc,Sp)-11
(Scheme 7). The recoordination reaction thus confirmed
that the free P-chiral P, N ligand (Sp)-13 was optically pure.
Subsequently, using a similar procedure, the optical purity
of the liberated P-chiral P, N ligand (Rp)-13 was also
confirmed.
(28) (a) Waid, R. D.; Meek, D. W. Inorg. Chem. 1984, 23, 778.
(b) Bartsch, R.; Hietkamp, S.; Morton, S.; Peters, H.; Stelzer, O. Inorg.
Chem. 1983, 22, 3264.
(29) (a) Corey, E. J.; Bailar, J. C. J. Am. Chem. Soc. 1959, 81, 2620.
(b) Roberts, N. K.; Bosnich, B. J. Am. Chem. Soc. 1981, 103, 2273.

3382 Organometallics, Vol. 29, No. 15, 2010
Chen et al.
Scheme 9
Figure 9. Molecular structure of complex (Sp)-20 with 50%
probability ellipsoids shown.
˚
Table 8. Selected Bond Distances (A) and Angles (deg) of Com-
plex (Sp)-20
phosphine prefers to adopt the position below the PdCN
ring, while the Et group occupies the position above the ring
to attain the least steric repulsion arising from the axial
methyl group with them (Scheme 8). As a result, the absolute
configuration of the phosphorus stereogenic center of the
favorable product should be R.
Pd(1)-P(1)
2.228(1)
2.238(1)
2.364(1)
2.351(1)
85.9(1)
P(2)-Pd(1)-Cl(1)
P(1)-Pd(1)-Cl(1)
P(2)-Pd(1)-Cl(2)
P(1)-Pd(1)-Cl(2)
Cl(1)-Pd(1)-Cl(2)
176.8(1)
91.05(4)
89.1(1)
Pd(1)-P(2) p
Pd(1)-Cl(1)
Pd(1)-Cl(2)
P(1)-Pd(1)-P(2)
174.6(1)
94.0(1)
In order to confirm the influence of the axial C-methyl
group of chiral palladium(II) naphthylamine on the stereo-
selectivity at the P-stereogenic center, one more asymmetric
hydrophosphination was carried out between diphenylvinyl-
phosphine and racemic secondary phosphine (()PhEtPH
using (Sc)-16 (Scheme 9). As the λ configuration will always
be observed for the chelate ring when the absolute configura-
tion of the carbon stereocenter is S, and the axial C-methyl
group projects perpendicularly below the square plane, the
stereoselectivity of the major product at the P-stereogenic
center will be S. Prior to purification, the 31P{1H} NMR
spectrum of the crude reaction mixture showed two pairs of
doublets at δ 68.4 (d, JPP = 24.7 Hz), 42.7 (d, JPP = 24.7 Hz)
and 61.7 (d, 1P, Jpp = 18.4 Hz), 40.2 (d, 1P, Jpp = 18.4 Hz) in
the ratio 14:1, respectively, indicating that a pair of diastereo-
meric complexes has been produced. After purifying by
chromatography, only the major product (Sc,Sp)-19 was
obtained. However, good-quality single crystals of complex
(Sc,Sp)-19 suitable for X-ray structure analysis could not be
obtained. The chiral naphthylamine auxiliary in (Sc,Sp)-19
was then removed chemoselectively from palladium tem-
plates by treatment with concentrated hydrochloric acid in
dichloromethane to give complex (Sp)-20. The 31P{1H}
NMR spectrum of the dichloro complex (Sp)-20 in CDCl3
exhibited a pair of doublets at δ 73.7 (d, 1P, Jpp = 11.4 Hz)
and 63.8 (d, 1P, Jpp=11.4 Hz). The single-crystal X-ray
diffraction analysis revealed that the isolated compound
was the expected dichloro complex (Sp)-20 (Figure 9). As
expected, the absolute configuration of the P(1) stereogenic
center was S. The selected bond lengths and angles are given
in Table 8.
gave the major product (Rc,Rc,Rp)-5a in which the newly
generated stereogenic carbon center had the absolute con-
figuration R. On the basis of the absolute chirality of the
newly formed stereogenic carbon center and the absolute
conformation of the five-membered diphosphine ring, four
possible stereoisomeric products are possible. As shown in
Scheme 10, isomers A and B have the same δ absolute con-
formation of the five-membered diphosphine ring, but differ
in their absolute configuration at the newly formed stereo-
genic carbon centers in that the absolute configuration of the
carbon center in isomer A is S, while in isomer B it is R.
Similarly, isomers C and D have different absolute configu-
rations at the carbon centers but the same λ absolute con-
formation of the five-membered diphosphine ring. To note,
the C-Me-substituted five-membered chelate ring is known
to adopt a single static chiral conformation with the C-Me
groups equatorially disposed.29 Therefore, the Me group
adopts an equatorial disposition in both isomers A and C,
but takes up the axial disposition in isomers B and D; the
favorable products should be isomers A and C, which
are represented by (Rc,Sc,Rp)-4a and (Rc,Rc,Rp)-5a. This is
confirmed by the X-ray crystallographic analysis that
isomer A is the complex (Rc,Sc,Rp)-4a, while isomer B is
complex (Rc,Rc,Rp)-5a.
Conclusion
In summary, chiral organopalladium template promoted
asymmetric hydrophosphination reactions have been de-
monstrated. These reactions proceeded with high regio-
and stereoselectivities under mild conditions. Optically pure
chiral diphosphines containing both phosphorus and carbon
stereogenic centers as well as P-stereogenic pyridylpho-
sphines were obtained in high yield and optical purity.
Interestingly, for hydrophosphination of E-isomer (Rc)-
3a, the absolute configuration of the new stereogenic carbon
center of the major product (Rc,Sc,Rp)-4a was S. On the
other hand, hydrophosphination of the Z-isomer (Rc)-3b

Article
It is important to note that PhEtPH is a chiral molecule,
and as a typical secondary phosphine, the inversion barrier
for PhEtPH is low at room temperature. However, the
Organometallics, Vol. 29, No. 15, 2010 3383
stereoselectivity at the P atom during product formation
is dictated by the chiral template, in spite of the use of the
racemic PhEtPH as the starting material. We are currently
investigating the catalytic properties of the transition metal
complexes containing these optically active phosphines.
Scheme 10
Experimental Section
Reactions involving air-sensitive compounds were performed
under a positive pressure of purified nitrogen. NMR spectra
were recorded at 25 °C on Bruker ACF 300 and AMX400
spectrometers. Optical rotations were measured on the specified
solution in a 0.1 dm cell at 25 °C with a Perkin-Elmer model 341
€
polarimeter. Melting points were determined on a Buchi melting
point B-540. Elementary analyses were performed by the Ele-
mental Analysis Laboratory of the Department of Chemistry at
the National University of Singapore.
The chiral palladium complexes (Rc)-1 and (Sc)-16,30 dip-
henylvinylphosphine,31 the E and Z forms of diphenyl-1-
propenylphosphine,32 and the racemic ethylphenylphosphine33
were prepared as previously described.
Caution! All perchlorate salts should be handled as potentially
explosive compounds. Care should be taken in handling highly
toxic cyanide compounds.
Hydrophosphination of (E)-Diphenyl-1-propenylphosphine.
Synthesis of {(Rc)-1-[1-(Dimethylamino)ethyl]naphthyl-C2,N}-
[(Sc,Rp)-1-ethylphenylphosphino-1-methyl-2-diphenylphosphino-
ethane-P1,P2]palladium(II) Perchlorate, (Rc,Sc,Rp)-4a. To a
Table 9. Crystallographic Data for Complexes (Rc,Sc,Rp)-4a, (Rc,Rc,Rp)-5a, (Sc,Rp)-8a, and (Rc,Rp)-8b
(Rc,Sc,Rp)-4a
(Rc,Rc,Rp)-5a
(Sc,Rp)-8a
(Rc,Rp)-8b
formula
fw
C
853.43
38H44Cl3NO4P2Pd
C39H45ClN2O4P2Pd
809.56
C23H26Cl2P2Pd
541.68
P2(1)
monoclinic
9.0468(3)
14.4313(6)
9.6325(4)
111.908(2)
1166.77(8)
2
223(2)
1.542
0.71073
1.168
0.08(4)
C23H26Cl2P2Pd
541.68
P2(1)
monoclinic
8.9434(3)
13.0220(4)
10.8172(4)
112.444(2)
1164.36(7)
2
223(2)
1.545
0.71073
1.171
0.01(5)
space group
cryst syst
P2(1)2(1)2(1)
orthorhombic
12.5387(8)
16.3372(10)
18.7069(11)
90
3832.1(4)
4
223(2)
1.479
0.71073
0.817
-0.01(3)
0.0444
0.0986
P2(1)2(1)2(1)
orthorhombic
10.5512(10)
15.4223(16)
23.297(2)
90
3791.0(7)
4
223(2)
˚
a/A
˚
b/A
˚
c/A
β/deg
3
˚
V/A
Z
T/K
F
calcd/g cm-3
λ/A
1.418
˚
0.71073
0.686
0.00(3)
0.0497
0.0928
μ/mm-1
Flack param
R1 (obsd data)a
wR2 (obsd data)b
P
0.0422
0.1318
0.0486
0.1349
P
P
P
a R1 =
Fo| - |Fc
/
|Fo|. b wR2 = { [w(Fo2 - Fc2)2]/ [w(Fo2)2]}1/2, w-1 = σ2(Fo2) þ (aP)2 þ bP.
Table 10. Crystallographic Data for Complexes (Rc,Rp)-11, (Rc,Sp)-11, (Rp)-12, (Sp)-12, and (Sp)-20
(Rc,Rp)-11
(Rc,Sp)-11
(Rp)-12
(Sp)-12
(Sp)-20
formula
fw
C30H36Cl3N2O4PPd
732.33
P2(1)
monoclinic
9.8594(4)
14.0726(6)
11.7832(5)
90.2890(10)
1634.87(12)
2
223(2)
1.488
0.71073
0.898
0.02(2)
C29H34ClN2O4PPd
647.40
C15.50H19Cl3NPPd
463.04
C15H18Cl2NPPd
420.57
P2(1)
monoclinic
10.1398(12)
8.5738(9)
19.062(2)
98.478(6)
1639.1(3)
4
173(2)
1.704
0.71073
1.545
0.00(2)
C22H24Cl2P2 Pd
527.65
P2(1)
monoclinic
8.6884(3)
14.7236(6)
9.3534(4)
109.031(2)
1131.13(8)
2
223(2)
1.549
0.71073
1.203
0.01(3)
space group
cryst syst
P2(1)2(1)2(1)
orthorhombic
10.1048(3)
11.6626(4)
24.2070(8)
90
2852.75(16)
2
173(2)
1.507
0.71073
0.837
-0.02(3)
0.0451
0.0956
P4(3)2(1)2
tetragonal
8.5216(2)
8.5216(2)
49.3018(17)
90
3580.18(17)
8
173(2)
˚
a/A
˚
b/A
˚
c/A
β/deg
3
˚
V/A
Z
T/K
F
calcd/g cm-3
λ/A
1.718
˚
0.71073
1.567
0.06(7)
0.0522
0.1308
μ/mm-1
Flack param
R1 (obsd data)a
wR2 (obsd data)b
P
0.0332
0.0864
0.0249
0.0746
0.0378
0.0903
P
P
P
a R1 =
Fo| - |Fc
/
|Fo|. b wR2 = { [w(Fo2 - Fc2)2]/ [w(Fo2)2]}1/2, w-1 = σ2(Fo2) þ (aP)2 þ bP.

3384 Organometallics, Vol. 29, No. 15, 2010
Chen et al.
PC = 2.3 Hz), 133.3 (d, 2C, JPC = 10.6 Hz), 134.8 (d, 2C, JPC =
10.6 Hz), 135.0 (d, 2C, JPC = 11.6 Hz).
solution of complex (Rc)-2a (0.1 g, 0.177 mmol) in dichloro-
methane was added silver perchlorate (0.044 g, 0.212 mmol) in
water (5 mL), and the mixture was stirred vigorously at room
temperature for 30 min. The reaction mixture was subsequently
filtered through Celite, washed with water (3 ꢀ 20 mL), and
dried with MgSO4. The mixture was then degassed and cooled to
-78 °C, and ethylphenylphosphine (0.025 g, 0.181 mmol) was
added. The mixture was stirred overnight, during which it was
allowed to gradually warm to ambient temperature. Upon
completion, the solvent was removed to give a dark brown
residue, which was purified by column chromatography (with
an eluting gradient starting from hexane-acetone, 6:1) to give
the major product as a white solid. Recrystallization of the crude
product from acetone-hexane gave pure (Rc,Sc,Rp)-4a as pale
yellow crystals: mp 239 °C; [R]D -78 (c 0.5, CH2Cl2); 0.082 g
(60% yield). Anal. Calcd for C37H42ClNO4P2Pd: C, 57.8; H, 5.5;
N, 1.8. Found: C, 57.7; H, 5.3; N, 1.7. 31P{1H} NMR (CDCl3,
J
Liberation of (Sc,Sp)-1-Ethylphenylphosphino-1-methyl-2-
diphenylphosphinoethane, (Sc,Sp)-9a. To the solution of dichloro
complex (Sc,Rp)-8a (0.03 g, 0.055 mmol) in dichloromethane
(10 mL) was added an aqueous solution of potassium cyanide
(1 g), and the resulting solution was stirred vigorously for 2 h. The
organic layer was separated, washed with water (3 ꢀ 20 mL), and
dried (MgSO4). Upon removal of solvent, white solid (Sc,Sp)-9a
was obtained: [R]D -118.4 (c 0.2, CH2Cl2); 0.016 g (80% yield).
31P{1H} NMR (CDCl3, 121MHz):δ-0.66 (d, 1P, JPP =21.2Hz),
-19.7 (d, 1P, JPP = 21.2 Hz). 1H NMR (CDCl3, 300 MHz): δ
0.98 (dt, 3H, JPH = 15.8 Hz, JHH = 7.9 Hz, CH2Me), 1.09 (dd,
3H, JPH = 13.2 Hz, JHH = 6.8 Hz, CHMe), 1.68-1.95 (m, 4H,
PCH2 þ CH2Me), 2.37-2.45 (m, 1H, CHMe), 7.28-7.46 (m, 15H,
aromatics).
Hydrophosphination of (Z)-Diphenyl-1-propenylphosphine. Hydro-
phosphination of (Z)-diphenyl-1-propenylphosphine was performed
in a similar manner to the hydrophosphination of (E)-diphenyl-1-
propenylphosphine.
121 MHz): δ 69.7 (d, 1P, JPP = 34.2 Hz), 30.0 (d, 1P, JPP
=
=
34.2 Hz). 1H NMR (CDCl3, 300 MHz): δ 1.09 (dd, 3H, JPH
11.1 Hz, JHH = 6.0 Hz, PCHMe), 1.18 (dt, 3H, JPH = 13.9 Hz,
JHH = 7.4 Hz, CH2Me), 2.03 (d, 3H, JHH = 6.2 Hz, CHMe),
2.07-2.13 (m, 1H, CHH0), 2.29-2.39 (m, 1H, CHH0), 2.45 (d,
3H, JPH = 0.81 Hz, NMe), 2.48-2.59 (m, 2H, CH2Me), 2.69
(dd, 3H, JPH =3.0 Hz, JHH = 2.6 Hz, NMe), 4.51 (qn, 1H,
JPH = JHH = 6.1 Hz, CHMe), 6.73-6.80 (m, 1H, PCHMe),
7.35-8.01 (m, 21H, aromatics). 13C NMR (CDCl3, 100 MHz): δ
10.1 (d, 1C, JPC = 3.7 Hz, CH2Me), 15.3 (dd, 1C, JPC = 20.1 Hz,
JPC = 5.3 Hz, CHMe), 15.4 (d, 1C, JPC = 32.1 Hz, CH2Me),
25.0 (s, 1C, PCHMe), 31.6 (dd, 1C, JPC = 31.2 Hz, JPC = 19.6
Hz, PCHMe), 36.2 (dd, 1C, JPC = 29.4 Hz, JPC = 11.2 Hz,
PCH2), 50.4 (d, 1C, JPC = 4.1 Hz, NMe), 51.9 (d, 1C, JPC = 2.9
Hz, NMe), 75.2 (dd, 1C, JPC = 4.4 Hz, JPC = 2.7 Hz, CHMe),
123.8 (s, 1C), 124.7 (d, 1C, JPC = 44.3 Hz), 125.2 (s, 1C), 126.5 (s,
2C), 126.9 (s, 1C), 128.6 (d, 1C, JPC = 35.5 Hz), 128.7 (s, 1C),
129.1 (d, 1C, JPC = 6.6 Hz), 129.8 (d, 2C, JPC = 10.5 Hz), 129.8
(d, 2C, JPC = 10.5 Hz), 130.1 (d, 2C, JPC = 9.7 Hz), 130.4 (d, 2C,
JPC = 10.2 Hz), 131.8 (d, 2C, JPC = 10.7 Hz), 132.1 (s, 1C),
133.1 (d, 1C, JPC = 2.1 Hz), 133.4 (d, 1C, JPC = 2.3 Hz), 134.6
(d, 2C, JPC = 11.1 Hz), 134.9 (d, 2C, JPC = 13.5 Hz), 150.7 (s,
1C), 156.5 (s, 1C), 157.7 (s, 1C).
Synthesis of [(Sc,Rp)-Dichloro-(1-ethylphenylphosphino-1-
methyl-2-diphenylphosphino)ethane-P1,P2]palladium(II), (Sc,Rp)-8a.
A solution containing (Rc,Sc,Rp)-4a (0.1 g, 0.189 mmol) in
dichloromethane was stirred vigorously with excess concen-
trated hydrochloric acid for 16 h. The reaction mixture was
then washed with water (3 ꢀ 10 mL) and dried (MgSO4).
Crystallization of the crude product from dichloromethane-
diethyl ether gave the dichloro complex (Sc,Rp)-8a as white
crystals: mp 221 °C; [R]D -100 (c 0.2, CH2Cl2); 0.091 g (88%
yield). Anal. Calcd for C23H26Cl2P2Pd: C, 51.0; H, 4.8. Found:
C, 50.9; H, 4.6. 31P{1H} NMR (CDCl3, 121 MHz): δ 80.3 (d,
Synthesis of {(Rc)-1-[1-(Dimethylamino)ethyl]naphthyl-C2,N}-
[(Rc,Rp)-1-ethylphenylphosphino-1-methyl-2-diphenylphosphino-
ethane-P1,P2]palladium(II) Perchlorate, (Rc,Rc,Rp)-5a. Pale
yellow crystals: mp 243 °C; [R]436 þ69.8 (c 0.5, CH2Cl2);
0.028 g (40% yield). Anal. Calcd for C37H42ClNO4P2Pd: C,
57.8; H, 5.5; N, 1.8. Found: C, 57.6; H, 5.2; N, 1.7. 31P{1H}
NMR (CDCl3, 121 MHz): δ 67.7 (d, 1P, JPP = 26.6 Hz), 34.9 (d,
1P, JPP = 26.6 Hz). 1H NMR (CDCl3): δ 1.25 (dd, 3H, JPH
=
14.1 Hz, JHH = 7.7 Hz, PCHMe), 1.31 (dt, 3H, JPH = 15.1 Hz,
JHH = 7.7 Hz, CH2Me), 1.87 (d, 3H, JHH = 6.2 Hz, CHMe),
2.20-2.33 (m, 2H, PCH2), 2.44 (dd, 3H, JPH = 3.3 Hz, JHH
=
3.2 Hz, NMe), 2.56-2.72 (m, 2H, CH2Me), 2.77 (brs, 3H,
NMe), 4.42 (qn, 1H, JPH
4
=
3JHH = 5.9 Hz, CHMe),
6.71-6.78 (m, 1H, PCHMe), 7.22-7.94 (m, 21H, aromatics).
13C NMR (CDCl3, 100 MHz): δ 11.2 (d, 1C, JPC = 2.5 Hz,
CH2Me), 14.4 (dd, 1C, JPC = 15.0 Hz, JPC = 4.4 Hz, CHMe),
15.2 (d, 1C, JPC = 28.2 Hz, CH2Me), 24.9 (s, 1C, PCHMe), 36.6
(dd, 1C, JPC = 29.4 Hz, JPC = 10.3 Hz, PCH2), 37.6 (dd, 1C,
JPC = 31.6 Hz, JPC = 18.8 Hz, PCHMe), 51.6 (dd, 1C, JPC
=
3.8 Hz, JPC = 1.5 Hz, NMe), 52.9 (d, 1C, JPC = 2.4 Hz, NMe),
74.8 (dd, 1C, JPC = 6.0 Hz, JPC = 2.6 Hz, CHMe), 123.6 (s, 1C),
125.1 (s, 1C), 126.4 (s, 1C), 127.8 (d, 1C, JPC = 44.3 Hz), 128.6
(d, 1C, JPC = 36.3 Hz), 128.7 (s, 1C), 129.1 (d, 1C, JPC = 24.4
Hz), 129.3 (d, 1C, JPC = 19.4 Hz), 129.7 (d, 2C, JPC = 9.4 Hz),
130.0 (d, 2C, JPC = 9.8 Hz), 130.2 (d, 2C, JPC = 10.1 Hz), 131.7
(d, 1C, JPC = 2.8 Hz), 132.1 (s, 1C), 132.4 (d, 1C, JPC = 2.6 Hz),
132.6 (d, 2C, JPC = 11.3 Hz), 132.9 (d, 2C, JPC = 11.0 Hz), 133.0
(d, 2C, JPC = 10.8 Hz), 134.2 (d, 2C, JPC = 13.2 Hz), 150.0 (s,
1C), 155.9 (s, 1C), 157.1 (s, 1C).
Synthesis of [(Rc,Rp)-Dichloro(1-ethylphenylphosphino-1-methyl-
2-diphenylphosphino)ethane-P1,P2]palladium(II), (Rc,Rp)-8b. White
crystals: mp 220; [R]D þ140 (c 0.2, CH2Cl2); 0.06 g (90% yield).
Anal. Calcd for C23H26Cl2P2Pd: C, 51.0; H, 4.8. Found: C, 50.6; H,
4.5. 31P{1H} NMR (CDCl3, 121MHz):δ80.8 (d, 1P, JPP = 6.4Hz)
and 58.9 (d, 1P, JPP =6.4Hz). 1HNMR(CDCl3, 300 MHz): δ1.22
(dd, 3H, JPH = 14.6 Hz, JHH = 7.1 Hz, CHMe), 1.41 (dt, 3H,
JPH = 11.3 Hz, JHH = 7.7 Hz, CH2Me), 2.38-2.57 (m, 2H,
CH2Me), 2.59-2.68 (m, 2H, PCH2), 2.70-2.80 (m, 1H, CHMe),
7.38-7.99 (m, 15H, aromatics). 13C NMR (CD2Cl2, 125 MHz): δ
10.1 (s, 1C, CH2Me), 14.6 (dd, 1C, JPC = 14.8 Hz, JPC = 13.0 Hz,
J
PP =5.5Hz),50.5(d,JPP =5.5Hz).1HNMR(CDCl3, 300 MHz):
δ 1.13 (dd, 3H, 3JPH = 9.2 Hz, 3JHH = 6.1 Hz, CHMe), 1.40 (dt,
3H, JPH = 18.2 Hz, JHH = 7.5 Hz, CH2Me), 2.11-2.31 (m, 2H,
CH2Me), 2.39-2.49 (m, 1H, CHH0), 2.59-2.67 (m, 1H, CHH0),
2.76-2.93 (m, 1H, CHMe), 7.43-8.13 (m, 15H, aromatics). 13
C
NMR (CD2Cl2, 100 MHz): δ 9.3 (s, 1C, CH2Me), 14.7 (dd, 1C,
PC = 22.8 Hz, JPC = 5.0 Hz, CHMe), 17.3 (d, 1C, JPC = 34.7
J
Hz, CH2Me), 32.3 (dd, 1C, JPC = 29.8 Hz, JPC = 15.0 Hz,
PCHMe), 37.1 (dd, 1C, JPC = 35.6 Hz, JPC = 14.9 Hz, PCH2),
126.1 (d, 1C, JPC = 48.3 Hz), 127.5 (d, 1C, JPC = 52.8 Hz), 129.3
(d, 2C, JPC = 11.6 Hz), 129.6 (d, 2C, JPC = 10.7 Hz), 129.9 (d,
2C, JPC = 11.3 Hz), 130.0 (d, 1C, JPC = 55.8 Hz), 132.4 (d, 1C,
JPC = 3.1 Hz), 133.09 (d, 1C, JPC = 2.6 Hz), 133.11 (d, 1C,
CHMe), 17.7 (d, 1C, JPC = 29.4 Hz, CH2Me), 35.9 (dd, 1C, JPC
30.9 Hz, JPC = 14.0 Hz, PCHMe), 38.4 (dd, 1C, JPC = 34.6 Hz,
PC = 16.1 Hz, PCH2), 128.4 (d, 1C, JPC = 42.7 Hz), 129.3 (d, 2C,
JPC = 8.7 Hz), 129.39 (d, 1C, JPC = 20.9 Hz), 129.44 (d, 1C, JPC
=
J
=
22.1 Hz), 129.6 (d, 2C, JPC = 9.4 Hz), 129.7 (d, 2C, JPC = 9.4 Hz),
132.5 (s, 2C), 132.7 (d, 1C, JPC = 2.0 Hz), 133.2 (d, 2C, JPC = 7.9
Hz), 134.0 (d, 2C, JPC = 9.0 Hz), 134.2 (d, 2C, JPC = 8.9 Hz).
Liberation of (Rc,Sp)-1-ethylphenylphosphino-1-methyl-2-
diphenylphosphinoethane, (Rc,Sp)-9b. White solid: [R]D þ92.6
(c 0.2, CH2Cl2); 0.017 g (84% yield). 31P{1H} NMR (CDCl3,
(30) Allen, D. G.; McLaughlin, G. M.; Robertson, G. B.; Steffen,
W. L.; Salem, G.; Wild, S. B. Inorg. Chem. 1982, 21, 1007.
(31) Aw, B. H.; Leung, P. H. Tetrahedron: Asymmetry 1994, 7, 1167.
(32) Grim, S. O.; Molenda, R. P. J. Org. Chem. 1980, 45, 250.
(33) Roberts, N. K.; Wild, S. B. J. Am. Chem. Soc. 1979, 101, 6254.

Article
Organometallics, Vol. 29, No. 15, 2010 3385
121 MHz): δ -0.38 (d, 1P, JPP = 18.4 Hz), -20.5 (d, 1P, JPP
18.4 Hz). 1H NMR (CDCl3, 300 MHz): δ 0.94 (dt, 3H, JPH
=
=
(m, 1H, CHH0), 2.16-2.38 (m, 2H, PCH2), 2.62-2.78 (m, 1H,
CHH0), 3.34-3.54 (m, 2H, CH2Me), 7.21-7.82 (m, 9H, arom-
atics). 13C NMR (CD2Cl2, 100 MHz): δ 8.0 (d, 1C, JPC = 3.5 Hz,
CH2Me), 18.9 (d, 1C, JPC = 30.5 Hz, CH2Me), 21.0 (d, 1C,
15.3 Hz, JHH = 7.7 Hz, CH2Me), 1.34 (dd 3H, JPH = 14.2 Hz,
JHH = 6.2 Hz, CHMe), 1.67-1.83 (m, 4H, PCH2 þ CH2Me),
2.12-2.19 (m, 1H, CHMe), 7.16-7.39 (m, 15H, aromatics).
Hydrophosphination of 2-Vinylpyridine. Synthesis of {(Rc)-
1-[1-(Dimethylamino)ethyl]naphthyl-C2,N}[(Rp)-1-ethylphenyl-
phosphino-2-(2-pyridine)ethane-N,P]palladium(II) Perchlorate,
(Rc,Rp)-11. To the solution of (()-PhEtPH (0.18 g, 1.30 mmol)
in dichloromethane was added bis(acetonitrile) palladium com-
plex (Rc)-10 (0.63 g, 1.30 mmol), and the temperature was then
reduced to -78 °C. Subsequently, 2-vinylpyridine (0.14 mL,
1.30 mmol) was added, and the reaction mixture was allowed to
warm to room temperature with stirring for 24 h. Upon frac-
tional crystallization, the major and minor products were then
crystallized from dichlomethane-diethyl ether as white crystals,
separately. (Rc,Rp)-11: white crystals; mp 257 °C; [R]D -157.5 (c
0.4, CH2Cl2); 0.43 g (52% yield). Anal. Calcd for C29H34ClN2-
O4PPd: C, 53.8; H, 5.3; N, 4.3. Found: C, 53.5; H, 5.2; N, 4.0.
J
PC = 36.8 Hz, PCH2), 36.9 (d, 1C, JPC = 4.3 Hz, CH2), 123.4 (s,
1C), 125.3 (s, 1C), 129.0 (d, 2C, JPC = 10.8 Hz), 129.5 (s, 1C),
131.6 (d, 1C, JPC = 2.8 Hz), 131.8 (d, 2C, JPC = 9.8 Hz), 140.0
(s, 1C), 155.0 (s, 1C), 158.8 (d, 1C, JPC = 5.6 Hz).
Synthesis of {(Sp)-Dichloro[1-ethylphenylphosphino-2-(2-
pyridine)ethane]}palladium(II), (Sp)-12. Synthesis of dichloro
complex (Sp)-3 was performed in a similar procedure to (Rp)-
12. [R]D þ198.0 (c 0.5, CH2Cl2); 0.056 g (87% yield). Anal. Calcd
for C15H18Cl2NPPd: C, 42.8; H, 4.3; N, 3.3. Found: C, 42.7; H,
4.3; N, 3.4.
Liberation of (Sp)-[1-Ethylphenylphosphino-2-(2-pyridine)]-
ethane, (Sp)-13. A solution of (Rp)-12 (0.03 g, 0.071 mmol) in
dichloromethane (10 mL) was stirred vigorously with a satu-
rated aqueous solution of potassium cyanide (1 g) for 2 h. The
organic layer was separated, washed with water (3 ꢀ 10 mL),
and dried (MgSO4). Upon removal of solvent, a white solid was
obtained: [R]D -26.1 (c 0.2, CH2Cl2); 0.017 g (81% yield).
31P{1H} NMR (CDCl3, 121 MHz): δ -18.5. 1H NMR (CDCl3,
300 MHz): δ 1.05 (dt, 3H, JPH = 15.5 Hz, JHH = 7.5 Hz,
CH2Me), 1.76 (q, 2H, JPH = JHH = 7.5 Hz, PCH2), 2.16 (t, 2H,
JHH = 8.4 Hz, CH2), 2.79-2.93 (m, 2H, CH2Me), 7.08-8.53
(m, 9H, aromatics). 13C NMR (CDCl3, 100 MHz): δ 10.1 (d, 1C,
1
31P{1H} NMR (CDCl3, 121 MHz): δ 33.0. H NMR (CDCl3,
300 MHz): δ 1.07 (dt, 3H, JPH = 12.2 Hz, JHH = 7.7 Hz,
CH2Me), 1.83-1.96 (m, 1H, CHH), 2.08 (d, 3H, JPH = 6.2 Hz,
CHMe), 2.23-2.33 (m, 2H, CH2Me), 2.49 (d, 3H, JPH = 2.8 Hz,
NMe), 2.57-2.69 (m, 1H, CHH), 2.84 (s, 3H, NMe), 3.36-3.70
(m, 2H, PCH2), 4.44 (qn, 1H, JPH = JHH = 6.2 Hz, CHMe),
7.04-7.98 (m, 15H, aromatics). 13C NMR (CDCl3, 100 MHz): δ
8.3 (s, 1C, CH2Me), 21.5 (d, 1C, JPC = 32.9 Hz, CH2Me), 23.8
(s, 1C, CHMe), 24.7 (d, 1C, JPC = 30.9 Hz, PCH2), 36.8 (s, 1C,
CH2), 47.2 (d, 1C, JPC = 1.6Hz, NMe), 51.4 (d, 1C, JPC = 1.6Hz,
NMe), 73.6 (d, 1C, JPC = 2.8 Hz, CHMe), 123.0 (s, 1C), 125.0
(d, 2C, JPC = 13.8 Hz), 126.0 (s, 1C), 126.5 (s, 1C), 126.5 (d, 1C,
J
PC = 3.7 Hz, CH2Me), 15.3 (dd, 1C, JPC = 20.1 Hz, JPC = 5.3
Hz, CHMe), 15.4 (d, 1C, JPC = 32.1 Hz, CH2Me), 25.0 (s, 1C,
PCHMe), 31.6 (dd, 1C, JPC = 31.2 Hz, JPC = 19.6 Hz,
PCHMe), 36.2 (dd, 1C, JPC = 29.4 Hz, JPC = 11.2 Hz, PCH2),
50.4 (d, 1C, JPC = 4.1 Hz, NMe), 51.9 (d, 1C, JPC = 2.9 Hz,
NMe), 75.2 (dd, 1C, JPC = 4.4 Hz, JPC = 2.7 Hz, CHMe),
123.8-157.7 (m, 28C, Ar).
Liberation of (Rp)-[1-Ethylphenylphosphino-2-(2-pyridine)]-
ethane, (Rp)-13. Liberation of (Sp)-[1-ethylphenylphosphino-
2-(2-pyridine)]ethanetoobtain freeligand(Rp)-13 was performed
in a similar procedure to the liberation of (Sp)-[1-ethylphenyl-
phosphino-2-(2-pyridine)]ethane. (Rp)-13: 0.015 g (71% yield);
[R]D þ26.1 (c 0.2, CH2Cl2).
JPC = 5.6 Hz), 128.9 (s, 1C), 129.0 (s, 1C), 129.7 (d, 2C, JPC =
10.6 Hz), 130.2 (d, 1C, JPC = 44.8 Hz), 131.8 (s, 1C), 132.0 (d,
1C, JPC = 2.3 Hz), 132.6 (d, 2C, JPC = 12.3 Hz), 133.9 (d, 1C,
JPC = 11.5 Hz), 140.6 (s, 1C), 145.8 (s, 1C), 149.56 (s, 1C), 149.61
(s, 1C), 160.2 (d, 1C, JPC = 2.6 Hz).
Synthesis of {(Rc)-1-[1-(Dimethylamino)ethyl]naphthyl-C2,
N}[(Sp)-1-ethylphenylphosphino-2-(2-pyridine)ethane-N,P]palla-
dium(II) Perchlorate, (Rc,Sp)-11. Mp 226 °C (dec); [R]D -256 (c
0.5, CH2Cl2); 0.26 g (31% yield). Anal. Calcd for C29H34-
ClN2O4PPd: C, 53.8; H, 5.3; N, 4.3. Found: C, 53.6; H, 5.2;
Hydrophosphination of Diphenylvinylphosphine. Synthesis of
{(Sc)-1-[1-(Dimethylamino)ethyl]naphthyl-C2,N}[(Sp)-1-ethylphe-
nylphosphino-2-diphenylphosphinoethane-P1,P2]palladium(II) Per-
chlorate, (Sc,Sp)-19. To a solution of complex (Sc)-17 (0.1 g, 0.181
mmol) in dichloromethane was added silver perchlorate (0.045 g,
0.217 mmol) in water (5 mL), and the mixture was stirred vigo-
rously at room temperature for 30 min. The mixture was filtered
through Celite, washed with water, and dried with magnesium
sulfate. The mixture was then degassed and cooled to -78 °C.
Ethylphenylphosphine (0.025 g, 0.181 mmol) was then added,
and the reaction mixture was stirred for 18 h. Upon completion,
the solvent was removed to give a dark brown residue, which was
purified by column chromatography (with an eluting gradient
starting from hexane-acetone, 8:1) give the products as white
solids. Recrystallization of the crude product from acetone-
hexane gave pure (Sc,Sp)-19 as white crystals: mp 267 °C; [R]D
þ62 (c 0.5, CH2Cl2); 0.027 g (20% yield). Anal. Calcd for
C36H40ClNO4P2Pd: C, 57.3; H, 5.3; N, 1.9. Found: C, 57.2; H,
1
N, 4.1. 31P{1H} NMR (CDCl3, 121 MHz): δ 34.3. H NMR
(CDCl3, 300 MHz): δ 1.17 (dt, 3H, JPH = 20.0 Hz, JHH = 7.5 Hz,
CH2Me), 1.85-2.02 (m, 2H, CH2), 2.08 (d, 3H, JPH = 6.3 Hz,
CHMe), 2.16-2.40 (m, 2H, CH2Me), 2.48 (d, 3H, JPH = 3.0 Hz,
NMe), 2.78 (s, 3H, NMe), 3.40-3.63 (m, 2H, PCH2), 4.41 (qn,
1H, JPH = JHH = 6.1 Hz, CHMe), 6.52-8.84 (m, 15H,
aromatics). 13C NMR (CDCl3, 100 MHz): δ 9.8 (d, 1C, JPC
=
2.2 Hz, CH2Me), 18.3 (d, 1C, JPC = 28.1 Hz, CH2Me), 24.3 (s,
1C, CHMe), 26.6 (d, 1C, JPC = 30.9 Hz, PCH2), 36.4 (d, 1C,
JPC = 2.8 Hz, CH2), 47.3 (s, 1C, NMe), 51.4 (d, 1C, JPC = 2.1 Hz,
NMe), 73.2 (d, 1C, JPC = 2.7 Hz, CHMe), 123.0 (s, 1C), 124.7 (s,
1C), 125.2 (s, 1C), 125.5 (d, 1C, JPC = 5.6 Hz), 126.1 (s, 1C),
126.3 (s, 1C), 128.6 (s, 1C), 128.7 (s, 1C), 128.9 (d, 2C, JPC
10.6 Hz), 130.8 (d, 1C, JPC = 49.8 Hz), 131.2 (d, 1C, JPC
=
=
2.5 Hz), 131.4 (s, 1C), 131.8 (d, 2C, JPC = 10.1 Hz), 135.7 (d, 1C,
PC = 12.2 Hz), 140.8 (s, 1C), 147.4 (s, 1C), 149.0 (d, 1C, JPC
1.7 Hz), 149.7 (s, 1C), 160.2 (d, 1C, JPC = 3.0 Hz).
J
=
5.3; N, 1.8. 31P{1H} NMR (CDCl3, 121 MHz): δ 68.4 (d, JPP
=
24.7 Hz), 42.7 (d, JPP = 24.7 Hz). 1H NMR (CD2Cl2, 300 MHz):
δ 1.24 (dt, 3H, JPH = 21.8 Hz, JHH = 7.5 Hz, CH2Me),
1.78-1.99 (m, 2H, PCH2), 2.06 (d, 3H, JPH = 6.2 Hz, CHMe),
2.28-2.50 (m, 2H, CH2Me), 2.55 (s, 3H, NMe), 2.60-2.66 (m,
1H, PCHH0), 2.70 (s, 3H, NMe), 2.75-2.99 (m, 1H, PCHH0),
4.60 (qn, 1H, JPH = 6.0 Hz, JHH = 6.2 Hz, CHMe), 7.07-8.20
(m, 21H, aromatics). 13C NMR (CD2Cl2, 125 MHz): δ 10.3 (d,
1C, JPC = 8.2 Hz, CH2Me), 19.4 (d, 1C, JPC = 32.3 Hz, CHMe),
25.5 (s, 1C, CH2Me), 27.6 (dd, 1C, JPC = 32.3 Hz, JPC = 19.5 Hz,
PCH2), 28.6 (dd, 1C, JPC = 25.9 Hz, JPC = 7.9 Hz, PCH2), 51.0
(d, 1C, JPC = 3.4 Hz, NMe), 52.3 (d, 1C, JPC = 3.2 Hz, NMe),
75.8 (s, 1C, CHMe), 124.3 (d, 1C, JPC = 4.7 Hz), 125.7 (s, 1C),
Synthesis of {(Rp)-Dichloro[1-ethylphenylphosphino-2-(2-pyri-
dine)ethane]}palladium(II), (Rp)-12. A solution containing (Rc,
Rp)-11 (0.1 g, 0.154 mmol) in dichloromethane was stirred
vigorously with excess concentrated hydrochloric acid for 16
h. The reaction mixture was then washed with water (3 ꢀ 10 mL)
and dried (MgSO4). Crystallization of the crude product from
dichloromethane-diethyl ether gave the dichloro complex (Rp)-
12 as yellow crystals: mp 235 °C; [R]D -198.0 (c 0.5, CH2Cl2);
0.059 g (90% yield). Anal. Calcd for C15H18Cl2NPPd: C, 42.8;
H, 4.3; N, 3.3. Found: C, 42.7; H, 4.3; N, 3.4. 31P{1H} NMR
(CDCl3, 121 MHz): δ 31.1. 1H NMR (CDCl3, 300 MHz): δ 1.34
(dt, 3H, JPH = 12.4 Hz, JHH = 7.2 Hz, CH2Me), 1.77-1.91

3386 Organometallics, Vol. 29, No. 15, 2010
Chen et al.
126.8 (dd, 2C, JPC = 5.6 Hz, JPC = 5.2 Hz), 127.0 (d, 2C, JPC
=
Crystal Structure Determination of (Rc,Sc,Rp)-4a, (Sc,Rp)-8a,
(Rc,Rc,Rp)-5a, (Rc,Rp)-8b, (Rc,Rp)-11, (Rc,Sp)-11, (Rp)-12, (Sp)-
12, and (Sp)-20. X-ray crystallographic data for all nine com-
plexes are given in Tables 9 and 10, respectively. Diffraction
data for complexes (Rc,Sc,Rp)-4a, (Rc,Rc,Rp)-5a, and (Rc,Rp)-11
were collected on SMART CCD diffractometer with graphite-
monochromated Mo KR radiation, and the other complexes on
a Bruker X8 CCD diffractometer with graphite-monochromated
Mo KR radiation. For all complexes, SADABS absorption
corrections were applied. All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were introduced at fixed dis-
tance from carbon atoms and were assigned fixed thermal para-
meters. The absolute configurations of all chiral complexes were
determined unambiguously using the Flack parameter.34
4.3 Hz), 128.8 (s, 1C), 129.1 (d, 2C, JPC = 7.7 Hz), 129.4 (s, 1C),
129.7 (d, 1C, JPC = 5.4 Hz), 130.4 (d, 2C, JPC = 8.1 Hz), 130.7 (d,
1C, JPC = 7.7 Hz), 132.2 (s, 1C), 132.5 (d, 2C, JPC = 6.4 Hz),
132.7 (s, 1C), 133.6 (d, 2C, JPC = 17.8 Hz), 134.5 (d, 2C, JPC =
9.5 Hz), 134.6 (d, 1C, JPC = 10.0 Hz), 135.3 (d, 2C, JPC = 10.7 Hz),
151.4 (s, 1C), 157.0 (s, 1C), 157.9 (s, 1C).
Synthesis of [(Sp)-Dichloro-(1-ethylphenylphosphino-2-diphe-
nylphosphino)ethane-P1,P2]palladium(II), (Sp)-20. Concentrated
hydrochloric acid (5 mL) was added to a solution of (Sc,Sp)-19
(0.1 g, 0.133 mmol) in dichloromethane (15 mL). The reaction
mixture was stirred vigorously at room temperature for 16 h,
washed with water (3 ꢀ 20 mL), and dried (MgSO4). Crystal-
lization of the crude product from dichloromethane-diethyl
ether gave the dichloro complex as white crystals: mp 253 °C;
[R]D þ43 (c 0.2, CH2Cl2); 0.063 g (89% yield). Anal. Calcd for
C22H24Cl2P2Pd: C, 50.1; H, 4.6. Found: C, 50.0; H, 4.4. 31P{1H}
NMR (CDCl3, 121 MHz): δ 73.7 (d, 1P, Jpp = 11.4 Hz), 63.8 (d,
Acknowledgment. We are grateful to Dr. Koh Lip Lin
and Ms. Tan Geok Kheng from the Chemistry Depart-
ment of National University of Singapore for analyzing
X-ray structures of complex (Rc,Sc,Rp)-4a, (Rc,Rc,Rp)-5a,
and (Rc,Rp)-11.
1P, Jpp = 11.4 Hz). 1H NMR (CDCl3): δ 1.28 (dt, 3H, 3JPH
=
3
20.5 Hz, JHH = 7.4 Hz, CH2Me), 1.88-2.01 (m, 1H, PhEtP-
CHH0), 2.15-2.23 (m, 1H, PhEtPCHH0), 2.27-2.40 (m, 2H,
CH2Me), 2.50-2.80 (m, 2H, Ph2PCH2), 7.36-7.64 (m, 15H,
aromatics). 13C NMR (CD2Cl2, 100 MHz): δ 8.7 (s, 1C,
CH2Me), 21.7 (d, 1C, JPC = 33.5 Hz, CH2Me), 24.6 (dd, 1C,
Supporting Information Available: For complexes (Rc,Sc,Rp)-
4a, (Sc,Rp)-8a, (Rc,Rc,Rp)-5a, (Rc,Rp)-8b, (Rc,Rp)-11, (Rc,Sp)-
11, (Rp)-12, (Sp)-12, and (Sp)-20, tables of crystal data, data
collection, solution and refinement, final positional parameters,
bond distances and angles, thermal parameters of non-hydrogen
atoms, and calculated hydrogen parameters. This material is
available free of charge via the Internet at http://pubs.acs.org
JPC = 32.1 Hz, JPC = 13.6 Hz, PCH2), 29.3 (dd, 1C, JPC = 34.9
Hz, JPC = 12.3 Hz, PCH2), 126.5-134.3 (m, 18C, Ar).
(34) Flack, H. D. Acta Crystallogr. 1983, A39, 876.