Asymmetric synthesis of 1,2-bis(diphenylphosphino)-1-phenylethane via a chiral palladium template promoted hydrophosphination reaction

Article abstract of DOI:10.1016/j.jorganchem.2009.06.024

An organopalladium(II) complex derived from (S)-N,N-dimethyl-1-(1-naphthyl)-ethylamine was employed as the chiral auxiliary to promote the asymmetric hydrophosphination reactions between diphenylphosphine and (E) or (Z)-diphenylphosphinostyrene in high re

Full text of DOI:10.1016/j.jorganchem.2009.06.024

Journal of Organometallic Chemistry 694 (2009) 3500–3505
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Asymmetric synthesis of 1,2-bis(diphenylphosphino)-1-phenylethane
via a chiral palladium template promoted hydrophosphination reaction
Yi Zhang, Lulu Tang, Sumod A. Pullarkat, Fengli Liu, Yongxin Li, Pak-Hing Leung *
Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 5 May 2009
Received in revised form 6 June 2009
Accepted 18 June 2009
Available online 26 June 2009
An organopalladium(II) complex derived from (S)-N,N-dimethyl-1-(1-naphthyl)-ethylamine was
employed as the chiral auxiliary to promote the asymmetric hydrophosphination reactions between
diphenylphosphine and (E) or (Z)-diphenylphosphinostyrene in high regio- and stereoselectivities at
low temperature with triethyl amine as external base. Optically active free ligand (R)-1,2-bis(diphenyl-
phosphino)-1-phenylethane was obtained in high yield subsequently. Mechanistic pathways explaining
the stereoselectivity of the chiral organopalladium template promoted hydrophosphination reactions are
also proposed.
Keywords:
Asymmetric hydrophosphination reaction
Chiral phosphine ligand
Chiral metal template
Ó 2009 Elsevier B.V. All rights reserved.
1
. Introduction
Diphosphines with one chiral carbon center have been shown to
2. Results and discussion
In the absence of a metal ion, diphenylphosphine shows no
reactivity with (E)- or (Z)-diphenylphosphinostyrene under ambi-
ent conditions. Therefore, as illustrated in Scheme 1, the (E)- and
(Z)-diphenylphosphinostyrene were coordinated to the chiral tem-
plate (S)-1 regioselectively to form complexes 2a and 2b, respec-
be effective ligands in asymmetric hydrogenation of prochiral ole-
fins and cross-coupling reactions [1–3]. It has been demonstrated
that a single chiral center may control the stereochemistry of these
catalytical reactions when the phosphine coordinates with metal
to form a rigid five-membered chelate ring [4]. The fixed phenyl
moiety in such scenarios provide a mechanism for enantiofacial
discrimination between substituents on the coordinated substrates
and the catalysts. 1,2-Bis(diphenylphosphino)-1-phenylethane
31
tively as solid powders in 99% isolated yields. The P NMR
spectrum in CDCl exhibited one single peak at d 33.3 and 23.7,
3
respectively for each coordination product. Complex 2a could not
be crystallized from the reaction solution while 2b was crystallized
(
Phenphos) is such a chiral ditertiary phosphine. It was first syn-
from dichloromethane-hexane as yellow prisms (81% yield), [
a]
D
thesised from chiral Mandelic Acid via a 3-steps transformation
+36.7 (c 0.3, CH Cl ). The molecular structure and the coordination
2
2
by King and Brown independently in 1978 and 1979, respectively
chemistry of 2b were determined by X-ray crystallography (Fig. 1).
Selected bond lengths and angles are given in Table 1.
[
5,6]. However, no improved synthetic approach was reported to
date. An attractive objective is the development of universal meth-
ods for the synthesis of such useful chiral phosphines from non-
chiral starting materials as opposed to the limited pool of natural
chirons. Our group have previously reported a series of chiral pal-
ladium template assisted asymmetric 1,2-addition reactions with
alkynes or alkenes in the absence of a base promoter [7–10]. It
has been reported that external bases play an important role in
some reactions, such as changing the addition pathways [11].
Herein we present the preparation of PhenPhos by chiral metal
template promoted asymmetric hydrophosphination reaction be-
tween diphenylphosphine and (E) or (Z)-diphenylphosphinosty-
rene [12] with triethylamine as external base.
Addition of stoichiometric quantities of aqueous silver perchlo-
rate to the dichloromethane solution containing the chloro com-
plexes 2a,b yielded the intermediate perchlorato complexes 3a,b,
respectively. Complexes 3a and 3b were used for hydrophosphin-
ation reactions separately. They were not isolated from their corre-
sponding previous reaction mixtures but were subsequently
treated with diphenylphosphine separately at À78 °C in the pres-
ence of 50% equivalent of triethylamine to give the hydrophosph-
ination products, 4a–d in 12 h with different ratios, respectively
(Scheme 1). It is noteworthy that the hydrophosphination reac-
tions did not occur without triethylamine as external base, even
in the presence of the chiral amine template. It needs to be high-
lighted that the reactions were highly regioselective, as the
diphenylphosphino groups were added to the b-carbon of the
diphenylphosphinostyrene to form five-membered chelate rings
exclusively [7–11].
*
Corresponding author. Tel.: +65 63168905; fax: +65 63166984.
E-mail address: pakhing@ntu.edu.sg (P.-H. Leung).
0
022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.06.024

Y. Zhang et al. / Journal of Organometallic Chemistry 694 (2009) 3500–3505
3501
Me
N
S
2
R
Me2
N
Me
Cl
2
Me
Cl
R
Ph2P
R'
AgClO4
Pd
Pd
P
R'
Ph
2
2
a, R=Ph, R'=H
b, R=H, R'=Ph
S
( )-1
Me2
Ph
P
Me2
N
Ph
P
2
2
Me
N
Me
Me
Ph
Ph
Pd
Pd
Me2
N
P
P
Ph
Ph
Me
OClO3
Ph2
Ph2
R
ClO -
4a
ClO -
4c
Pd
PPh H
4
4
2
P
R'
Ph
NEt3
2
Me2
Ph
P
Me2
Ph
P
2
2
Me
N
N
Pd
Pd
3
a, R=Ph, R'=H
b, R=H, R'=Ph
P
P
Ph
Ph
2
2
ClO -
ClO -
4
4
4
b
4d
Scheme 1.
Fig. 1. Molecular structure and absolute configuration of 2b.
Upon treatment of complex 3a with diphenylphosphine, three
of 6:1 as yellow crystals. The minor diastereomers, 4c or 4d, were
not present in this crystallized material. The diastereomeric mix-
ture 4a and 4b was subsequently redissolved in dichloromethane
and fractional crystallization was attempted. A 1:1 mixture of 4a
and 4b co-crystallized as yellow prisms from dichloromethane-
diethyl ether and its X-ray structure was determined. Selected
bond lengths and angles are given in Table 2 and Table 3. The opti-
cally pure complex 4a was left in the mother liquid. The X-ray crys-
tallography affirms that two independent molecules are present in
one asymmetric unit. The two molecules not only differ in relative
bond lengths and angles but also in the absolute configuration of
the chiral carbon centers (C16 and C62). The molecular structure
products were formed exhibiting three pairs of doublets in the
3
1
crude
P NMR spectrum in the ratio 12:2:1: d 48.2, 50.5
(
6
3
J
PP = 36.3 Hz) for 4a, 46.5, 50.1 (JPP = 36.6 Hz) for 4b and 25.1,
7.9 (JPP = 37.4 Hz) for 4c. Similarly, upon treatment of complex
b with diphenylphosphine, the reaction gave a 6:1 mixture of dia-
stereomers 4a and 4b, along with trace amounts of 4c and 4d (d
5.9 and 66.6 (JPP = 37.6 Hz)). Unfortunately, the major product
a could not be isolated efficiently by chromatography or frac-
tional crystallization. The two diastereomers 4a and 4b always
co-crystallized together as a mixture. The mixture of 4a and 4b
could be obtained from dichloromethane-hexane with the ratio
2
4

3
502
Y. Zhang et al. / Journal of Organometallic Chemistry 694 (2009) 3500–3505
Table 1
Selected bond lengths (Å) and bond angles (°) of 2b.
Pd(1)–P(1)
Pd(1)–Cl(1)
Pd(1)–N(1)
Pd(1)–C(1)
P(1)–C(15)
C(15)–C(16)
N(1)–C(11)
C(11)–C(10)
2.2617(6)
2.4047(6)
2.1283(19)
2.014(2)
1.810(2)
1.338(3)
1.510(3)
1.506(3)
1.384(3)
93.90(2)
174.74(5)
93.78(6)
164.92(6)
91.36(5)
81.05(8)
128.96(17)
130.83(19)
C(10)–C(1)
P(1)–Pd(1)–Cl(1)
P(1)–Pd(1)–N(1)
P(1)–Pd(1)–C(1)
C(1)–Pd(1)–Cl(1)
Cl(1)–Pd(1)–N(1)
C(1)–Pd(1)–N(1)
P(1)–C(15)–C(16)
C(15)–C(16)–C(17)
Table 2
Selected bond lengths (Å) and bond angles (°) of 4a.
Pd(1)–C(1)
Pd(1)–P(1)
Pd(1)–N(1)
Pd(1)–P(2)
P(1)–C(16)
P(2)–C(15)
C(1)–Pd(1)–N(1)
N(1)–Pd(1)–P(2)
N(1)–Pd(1)–P(1)
C(1)–Pd(1)–P(2)
C(1)–Pd(1)–P(1)
P(1)–Pd(1)–P(2)
P(1)–C(16)–C(15)
P(2)–C(15)–C(16)
2.073(3)
2.3587(7)
2.146(3)
2.2442(8)
1.863(3)
1.842(3)
80.19(12)
175.28(8)
100.17(8)
95.12(9)
177.98(10)
84.50(3)
104.47(19)
110.3(2)
Fig. 2. Molecular structure and absolute configuration of 4a.
raphy studies, complex 4b is adopting a sterically unfavorable d
ring conformation as it shows a significant distortion angle at the
palladium(II) center and significant deviation from the planarity.
The optically pure complex 4a was obtained form the mother li-
quid after removal of co-crystallized 4a and 4b completely. As
illustrated in Scheme 2, conc. HCl was added subsequently to re-
move the chiral naphthylamine auxiliary resulting in the optically
active dichloro complex (R)-5 as yellow prisms (90% yield) from
D 2 2
a] +113 (c 0.3, CH Cl P
). The 31
dichloromethane-diethyl ether: [
NMR spectrum of (R)-5 in CDCl exhibited two doublets at d 43.0,
4.0 (JPP = 2.6 Hz). The molecular structure and the absolute ste-
reochemistry of (R)-5 were determined by X-ray crystallography
Fig. 4). The five-membered chelate ring has the asymmetric skew
3
7
(
Table 3
conformation of k helicity with the phenyl substituent on the new
formed carbon center of R absolute configuration occupying an
equatorial position. Aqueous potassium cyanide was added to a
dichloromethane solution of (R)-5. After stirring vigorously for
1 h, the colorless organic layer was separated, washed with water
Selected bond lengths (Å) and bond angles (°) of 4b.
Pd(2)–C(47)
Pd(2)–P(4)
Pd(2)–N(2)
Pd(2)–P(3)
P(3)–C(62)
P(4)–C(61)
C(47)–Pd(2)–N(2)
N(2)–Pd(2)–P(4)
N(2)–Pd(2)–P(3)
C(47)–Pd(2)–P(4)
C(47)–Pd(2)–P(3)
P(4)–Pd(2)–P(3)
P(3)–C(62)–C(61)
P(4)–C(61)–C(62)
2.065(3)
2.2358(8)
2.136(3)
2.3684(8)
1.871(4)
1.839(4)
80.05(12)
170.19(9)
101.24(8)
95.39(9)
170.87(10)
84.65(3)
105.5(2)
110.6(3)
4
and dried (MgSO ). Upon the removal of solvent, a white solid
of complex 4a is given in Fig. 2, which has an R absolute configura-
tion at the newly formed chiral carbon center C16 and the molecu-
lar structure of complex 4b is given in Fig. 3, which has an S
absolute configuration at the newly formed chiral carbon center
1
C62. The geometry at Pd in complex 4a is slightly distorted square
plane with a distortion angle of 2.0° and a mean deviation from
planarity of 0.013 Å; the newly formed five-membered ring is
found to adopt the k ring conformation. On the other hand, the
2
geometry at Pd in complex 4b exhibits a significantly distorted
square plane with a distortion angle of 13.2° and a mean deviation
from planarity of 0.165 Å; the newly formed five-membered ring is
found to adopt d ring conformation. Based on the X-ray crystallog-
Fig. 3. Molecular structure and absolute configuration of 4b.

Y. Zhang et al. / Journal of Organometallic Chemistry 694 (2009) 3500–3505
3503
Me
2
Ph
P
Ph
P
2
Ph
P
2
2
H C
N
3
Ph
Cl
Cl
Ph
Ph
con.HCl
KCN
+
Pd
Pd
P
Ph
P
Ph
P
Ph2
ClO4-
2
2
4a
(
R
)-5
R
( )-(-)-Phenphos
Scheme 2.
are identical to those recorded for 4a and 4c generated in the ori-
3
1
ginal hydrophosphination reaction. The P NMR spectrum (CDCl
of the crude recomplexation mixture form (R)-(-)-Phenphos and
R)-6 exhibited two pairs of doubles at d 46.5, 50.1 (JPP = 36.6 Hz)
3
)
(
and 25.9, 66.6 (JPP = 37.6 Hz). These signals were identical with
those observed for 4b and 4d. Complexes 4b and 7, 4d and 8 are
thus two pairs of enantiomers. As expected, the enantiomeric com-
plexes exhibited the same NMR chemical signals. Thus, the NMR
studies confirmed that diastereomer 4d was indeed a minor prod-
uct of the asymmetric synthesis.
In general, (E)- and (Z)-diphenylphosphinostyrene generated
the hydrophosphination products 4a and 4b with the same ratio
of 6:1, which is not in agreement with what we observed in our
previous experiments of hydrophosphination reactions [9]. In the
previous studies, trans and cis coordinated alkenes did not yield
major products with same chirality. However, this can be ex-
plained by consideration of the possible reaction pathways as illus-
trated in Scheme 4. In principle, the transition state A and B are
electronically more favorable than other possible pathways. The
p
-accepting styrenylphosphine is coordinated in the trans position
to the -donating NMe group, while the electron-rich phosphido
moiety is located trans to the strong -accepting ortho-metalated
r
p
carbon atom [13]. With pathway A, the (E)-isomer 3a would gener-
ate complex 4a as the major product, in which the new stereogenic
carbon center adopts the R absolute configuration. In this transi-
tion state, severe interchelate repulsions between the chiral auxil-
iary and the reacting phosphorus substrates are absent. With
pathway B, the (E)-isomer 3a would generate complex 4b as minor
product due to the influence of the interchelate repulsions by
which the new stereogenic carbon center adopts the S absolute
configuration. However, with pathway A, the (Z)-isomer 3b would
only generate complex 4b as minor product because of the severe
interchelate repulsions between the chiral auxiliary and phenyl
substrate present in 3b.
Fig. 4. Molecular structure and absolute configuration of (R)-5.
(
R)-(-)-Phenphos [5] was obtained in 95% yield. The 31P NMR spec-
trum of the free ligand (R)-(-)-Phenphos in CDCl exhibited two
3
doublets at d À21.2, 3.6 (JPP = 17.4 Hz).
To establish the identities of the two minor products 4c and 4d,
the liberated optically pure (R)-(-)-Phenphos was recoordinated to
(
S)-6 as illustrated in Scheme 3. The 31P NMR spectrum (CDCl
3
) of
the crude product exhibited only two pairs of doubles at d 48.2,
0.5 (JPP = 36.3 Hz) and 25.1, 67.9 (JPP = 37.4 Hz). These signals
For this reason, the (Z)-isomer 3b would prefer generation of
complex 4a as major product through pathway B. It is noteworthy
that complex 4a which was generated from 3b through pathway B
5
Me
Me
N
Me
N
2
2
Ph
P
2
Ph
P
2
2
Ph
P
N
2
H C
H C
3
H C
3
3
Ph
NCMe
NCMe
+
+
Ph
+
Pd
Pd
Pd
+
P
P
Ph
Ph
P
Ph
ClO -
Ph
2
ClO - Ph
ClO4-
4
4
2
2
(
S
)-6
(
R
)-(-)-Phenphos
4a
4c
Me
Me
2
Me
N
2
Ph
P
2
2
Ph2
P
Ph
P
N
N
2
H C
H C
3
H C
3
3
Ph
NCMe
NCMe
+
+
+
Ph
Pd
Pd
Pd
+
P
Ph
P
P
ClO -
2
- Ph
ClO4-
)-6
ClO4
2
Ph
4
2
(
R
(R
)-(-)-Phenphos
7
8
Scheme 3.

3
504
Y. Zhang et al. / Journal of Organometallic Chemistry 694 (2009) 3500–3505
Me
Me
N
CC
N
CC
H
H
Me
Me
Ph
R'
pathway A
R'
Ph
Ph
R
R
Ph
P
P
P
P
Ph
Ph
Ph
Ph
3
a: R = Ph, R' = H
4a: R = Ph, R' = H
3
b: R = H, R' = Ph
4b: R = H, R' = Ph
Me
Me
CC
N
CC
N
H
Me
H
Me
pathway B
Ph
Ph
P
Ph
Ph
P
P
R
P
Ph
Ph
R
Ph
Ph
R'
R'
3
b: R = Ph, R' = H
4b: R = Ph, R' = H
3
a: R = H, R' = Ph
4a: R = H, R' = Ph
Scheme 4.
adopted a d ring conformation initially. It would however transfer
to a more stable k ring conformation easily in solution. From the
discussions above, we believe that (E)- and (Z)-diphenylphosphi-
nostyrene both generate complex 4a as major product but through
different pathways.
In conclusion, the synthesis of chiral diphosphine via chiral
amine template assisted asymmetric hydrophosphination has been
demonstrated. Triethylamine is essential to this reaction as it play
the role as external base. The reactions proceeded with high regio-
and stereoselectivities. Further investigations on the synthesis of
similar class chiral diphosphines with various substituents and
functionalities are currently in progress as well as their applica-
tions in various catalytic scenarios.
1.090 g (99% yield). [
c).Anal. Calc. for C34
a
]
D
+75.6 (c 0.2, CH
2
Cl
2
); Mp 120–121 °C (de-
H
33ClNPPd: C, 65.0; H, 5.3; N, 2.2. Found: C,
3
1
1
64.7; H, 5.4; N, 2.2% P NMR (CDCl
3
) d 33.3; H NMR (CDCl
3
) d
3
2.09 (d, 3H, CHMe, JHH = 6.2 Hz), 2.82 (s, 3H, NMeeq), 3.03 (d, 3H,
4
3
4
J
PH = 3.3 Hz, NMeax), 4.41 (qn, 1H,
J
HH = JPH = 6.2 Hz, CHMe),
2
3
6.61 (dd, 1H,
J
PH = 17.6 Hz,
JHH = 8.8 Hz, PCH), 6.76 (dd, 1H,
3
3
J
PH = 6.1 Hz, JHH = 8.8 Hz, PCCH), 6.79–8.07 (m, 21H, aromatics).
3
2
.2. Preparation of complex [(S)-Chloro[1-[1-(dimethylamino)ethyl]-
-naphthalenyl-C,N][(Z)-Diphenyl-phosphinostyrene -P]palladium(II),
2
b
A
mixture of (S)-1 (0.594 g, 0.873 mmol) and (Z)-diph-
enylphosphinostyrene (0.504 g, 1.748 mmol) was stirred in dichlo-
romethane (50 mL) at room temperature for 2 h. The solvent was
removed and complex 2b was obtained from dichloromethane
3
. Experimental
Reactions involving air-sensitive compounds were performed
and diethyl ether as yellow crystals, 0.889 g (81% yield). [
a]D
under an inert atmosphere of argon using standard Schlenk tech-
niques. Solvents were dried and freshly distilled according to stan-
dard procedures and degassed prior to use when necessary. The H
+36.7 (c 0.3, CH Cl ); Mp183-184 °C (dec). Anal. Calc. for
2
2
C34H33ClNPPd: C, 65.0; H, 5.3; N, 2.2. Found: C, 64.8; H, 5.4; N,
1
31
1
3 3
2.2%. P NMR (CDCl ) d 23.7; H NMR (CDCl ) d 1.80 (d, 3H, CHMe,
3
1
1
3
4
and P{ H} NMR spectra were recorded at 25 °C on Bruker Avance
00 and 500 spectrometers. Optical rotations were measured on
the specified solution in a 0.1 dm cell at 20 °C with a Perkin–Elmer
41 polarimeter. Elemental analysis was performed by the Ele-
JHH = 6.2 Hz), 2.58 (d, 3H, JPH = 1.2 Hz, NMeeq), 2.94 (d, 3H,
4J = 3.3 Hz, NMeax), 4.29 (qn, 1H, JHH = J = 6.2 Hz, CHMe),
3
4
3
P
H
P
H
2
3
6.72 (dd, 1H, JPH = 13.1 Hz, JHH = 6.6 Hz, PCH), 6.84 (dd, 1H,
JPH = 8.6 Hz, J = 6.6 Hz, PCCH), 7.03–7.87 (m, 21H, aromatics).
HH
3
3
3
mental Analysis Laboratory of the Division of Chemistry and Bio-
logical Chemistry at Nanyang Technological University. Melting
points were measured using the SRS Optimelt Automated Melting
Point System, SRS MPA100.
3.3. Hydrophosphination of [(S)-Chloro[1-[1-(dimethylamino)ethyl]-
2-naphthalenyl-C,N][(E/Z)-Diphenyl-phosphinostyrene-P]palladium
(II), 2a/b. Preparation of diastereomeric complexes 4a,b
The chiral palladium complex (S)-1 [14], tertiary phosphine (E)
or (Z)-diphenylphosphinostyrene [12] were prepared according to
literature methods.
Caution: Perchlorate salts of metal complexes are potentially
explosive compounds and should be handled with care.
Complex 2a or 2b (0.582 g, 0.926 mmol) in dichloromethane
(100 mL) and aqueous silver perchlorate (0.400 g, 1.775 mmol)
were stirred vigorously at room temperature for 2 h. The mixture
was filtered through Celite, washed with water (3 Â 30 mL) and
4
dried with MgSO . The mixture was then degassed and treated
3
2
2
.1. Preparation of complex [(S)-Chloro[1-[1-(dimethylamino)ethyl]-
-naphthalenyl-C,N][(E)-Diphenyl-phosphinostyrene-P]palladium(II),
a
with diphenylphosphine (0.172 g) and triethylamine (0.047 g) at
À78 °C for 12 h. The crude product was recrystallized from dichlo-
romethane and diethyl ether to give the 1:1 mixture of 4a,b as yel-
low crystals, 0.171 g (21% yield). [
235 °C (dec). Anal. Calc. for C46H44ClNO P Pd: C, 62.9; H, 5.1; N,
D 2 2
a] +48.4 (c 0.6, CH Cl ); Mp
A
mixture of (S)-1 (0.590 g, 0.867 mmol) and (Z)-diph-
4
2
enylphosphinostyrene (0.501 g, 1.738 mmol) was stirred in dichlo-
romethane (50 mL) at room temperature for 2 h. The solvent was
removed and complex 2a was obtained as yellow powder,
1.6. Found: C, 62.4; H, 5.2; N, 1.6%.
Spectroscopic assignments follow. [(S)-chloro[1-[1-(dimeth-
ylamino) ethyl]-2-naphthalenyl-C,N][(R)-1,2-bis(diphenylphos-

Y. Zhang et al. / Journal of Organometallic Chemistry 694 (2009) 3500–3505
3505
Table 4
Table 5
Selected bond lengths (Å) and bond angles (°) of (R)-5.
Crystallographic data for complexes 2b, 4a,b, (R)-5.
Pd(1)–P(2)
Pd(1)–P(1)
Pd(1)–Cl(1)
Pd(1)–Cl(2)
P(1)–C(13)
P(2)–C(14)
C(13)–C(14)
C(14)–C(15)
P(2)–Pd(1)–P(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)
P(2)–C(14)–C(13)
P(1)–C(13)–C(14)
2.2346(9)
2.2474(9)
2.3693(10)
2.3540(9)
1.836(3)
1.874(3)
1.536(4)
1.522(4)
85.81(3)
175.31(4)
95.34(3)
86.56(4)
170.09(3)
92.77(4)
105.16(19)
109.1(2)
2b 4a,b
(R)-5
Formula
C
34
H
33 Cl N P Pd
C
46
H
44 ClN O
4
P
2
33 4 2
C H30 Cl N P Pd
Pd
M
628.43
Cc
878.61
P1
736.71
ꢀ
ꢀ
Space group
Crystal system
a (Å)
P1
Orthorhombic
10.9100(2)
15.8210(3)
16.7419(3)
2889.77(9)
4
Triclinic
9.8084(4)
13.7477(4)
15.7166(5)
2081.31(12)
2
Triclinic
8.7544(4)
8.7570(4)
11.2458(5)
799.08(6)
1
173(2)
0.71073
1.037
b (Å)
c (Å)
3
V (Å )
Z
T (K)
273(2)
298(2)
k (Å)
0.71073
0.814
0.71073
0.631
À1
l
(mm
)
a
R
1
(observed data)
wR (observed
data)b
Flack parameter
0.0291
0.0353
0.0311
0.0319
2
0.0395
0.0457
À0.020(16)
À0.022(13)
0.023(18)
phino)-1-phenylethane-P ,P ] palladium (II) Perchlorate 4a: 31P
NMR (CDCl ) d 1.98 (d,
) d 48.2, 50.5 (JPP = 36 Hz); 1H NMR (CDCl
H, CHMe, JHH = 6.2 Hz), 2.40 (s, 3H, NMeeq), 2.58 (s, 3H, NMeax),
.62–3.25 (m, 2H, PCH ), 3.51–3.65 (m, 1H, PCH), 4.55 (qn, 1H,
HH = JPH = 6.2 Hz, CHMe), 6.36–8.35 (m, 31H, aromatics).
(S)-Chloro[1-[1-(dimethylamino)ethyl]-2-naphthalenyl-C,N][(S)-1,2-
1
2
a
R1
wR
=
R
= {
||F |À|F ||/
0
c 0
R|F |.
b
c 0 0
) ]/R = r
[w(F 2)2]}1/2, wÀ1 2(F )2 + (aP)2 + bP.
2 2
R
[w(F
0
2ÀF
3
3
3
2
3
2
J
2
3
4
while the hydrogen atoms were introduced at calculated positions
and refined riding on their carrier atoms. The absolute configura-
tion of the chiral complex was determined unambiguously by
using the Flack parameter [16].
[
1
2
bis(diphenylphosphino)-1-phenylethane-P ,P ]palladium(II) Perchlorate
3
1
1
4
(
b: P NMR (CDCl
3
) d 46.5, 50.1 (JPP = 37 Hz), H NMR (CDCl
HH = 6.2 Hz), 2.24 (s, 3H, NMeeq), 2.62–3.25 (m, 2H,
), 2.96 (s, 3H, NMeax), 3.51–3.65 (m, 1H, PCH), 4.44 (qn, 1H,
3
) d 1.64
3
d, 3H, CHMe,
J
PCH
2
Supplementary material
3
4
J
HH = JPH = 6.2 Hz, CHMe), 6.36–8.35 (m, 31H, aromatics).
CCDC 728927, 728928 and 728929 contain the supplementary
crystallographic data for complexes 4a,b, (R)-5, and 2b. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Center via www.ccdc.cam.ac.uk/data_request/cif.
3
.4. Removal of chiral auxiliary: synthesis of (R)-Dichloro[1,2-
1
2
bis(diphenylphosphino)-1-phenylethane-P ,P ]palladium(II), (R)-5
Concentrated HCl (10 mL) was added to a solution of 4a (0.200 g,
0
.228 mmol) in dichloromethane (30 mL). The reaction mixture was
stirred vigorously at room temperature for 12 h, washed with water
3 Â 20 mL), and dried (MgSO ). Crystallization of the crude product
form dichloromethane and diethyl ether gave the dichloro complex
as yellow crystals, 0.150 g (90% yield). [ +113 (c 0.3, CH Cl ); Mp:
Pd: C, 53.8; H, 4.1. Found: C,
Acknowledgements
(
4
We are grateful to Nanyang Technological University for sup-
porting this research and the research scholarships to Y.Z., L.L.T.
and F.L.L.
a
P
4 2
]
D
2
2
2
5
10 °C (dec). Anal. Calc. for C33
H
30Cl
): d 43.0, 74.0 (JPP = 2.6 Hz); H NMR
) d 2.70–2.97 (m, 2H, PCH CHPh ), 3.93–4.00 (m, 1H, PCHPh),
.55–8.29 (m, 25H, aromatics).
3
1
1
3.5; H, 4.3%. P NMR (CDCl
3
References
(
CDCl
3
2
,
[
1] F. Morandini, G. Pilloni, G. Consiglio, A. Mezzetti, Organometallics 14 (1995)
418–3422.
2] T. Yoshikuni, J.C. Bailar Jr., Inorg. Chem. 21 (1982) 2129–2133.
6
3
[
3.5. Liberation of (R)-1,2-bis(diphenylphosphino)-1-phenylethane,(R)-
[3] G. Consiglio, O. Piccolo, L. Roncetti, F. Morandini, Tetrahedron 42 (1986) 2043–
2053.
(
-)-Phenphos
[
4] J.M. Brown, B.A. Murrer, J. Chem. Soc., Perkin Trans. 2: Phys. Org. Chem. (1982)
89–497.
5] R.B. King, J. Bakos, C.D. Hoff, L. Marko, J. Org. Chem. 44 (1979) 1729–1731.
4
A solution of (R)-5 (0.066 g, 0.0896 mmol) in dichloromethane
[
was stirred vigorously with a saturated aqueous solution of potas-
sium cyanide (1.00 g) for 2 h. The organic layer was separated,
[6] J.M. Brown, B.A. Murrer, Tetrahedron Lett. 20 (1979) 4859–4862.
[
[
[
7] L. Tang, Y. Zhang, D. Luo, Y. Li, K.F. Mok, W.C. Yeo, P.H. Leung, Tetrahedron Lett.
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7463.
4
washed with water (3 Â 20 mL), and dried (MgSO
of solvent, a white solid was obtained: 0.050 g (95% yield). P NMR
CDCl
) d À21.2, 3.6 (JPP = 17.4 Hz). Other physical properties are
consistent with those reported previously [3] (Table 4).
4
). Upon removal
3
1
9] W.C. Yeo, S.T. Tee, G.K. Tan, L.L. Koh, P.H. Leung, Inorg. Chem. 43 (2004) 8102–
(
3
8109.
[
[
10] M. Yuan, S.A. Pullarkat, M. Ma, Y. Zhang, Y. Huang, Y. Li, A. Goel, P.H. Leung,
Organometallics 28 (2009) 780–786.
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Lett. 49 (2008) 1762–1767.
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Inorg. Chem. 21 (1982) 1007–1014.
3.6. X-ray crystal structure determination of complexes 2b,4a,b and
(
R)-5
[
[
[
Crystal data for all complexes and a summary of the crystallo-
graphic analysis are given in Table 5. Diffraction data were col-
lected on a Bruker X8 CCD diffractometer with Mo K radiation
graphite monochromator). SADABS absorption corrections were ap-
plied [15]. All non-hydrogen atoms were refined anisotropically,
[
15] G.M. Sheldrick, SHELX-97 Programs for Crystal Structure Analysis, University of
Göttinen, Germany, 1997.
[16] H.D. Flack, Acta Crystallogr., Sect. A 39 (1983) 876–881.
a
(