Asymmetric hydroarsination reactions toward synthesis of alcohol functionalised C-chiral As-P ligands promoted by chiral cyclometallated complexes

Article abstract of DOI:10.1016/j.jorganchem.2011.09.016

The asymmetric hydroarsination reactions between diphenylarsine and 3-diphenylphosphanyl-but-3-en-1-ol and 2-diphenylphosphanyl-prop-2-en-1-ol have been achieved using the organopalladium complex containing ortho-metallated (R)-[1-(dimethylamino)ethylnaphthalene as the chiral reaction template in high stereoselectivities under mild conditions. Hydroarsination of 3-diphenylphosphanyl-but-3-en-1-ol with diphenylarsine generated only one stereoisomer as five-membered As-P bidentate chelate on chiral naphthylamine palladium template. Using the same chiral metal template, similar hydroarsination reaction was carried out on 2-diphenylphosphanyl-prop-2-en-1-ol which gave two different products in the ratio of 2.6 to 1. The major isomer was identified as the expected five-membered As-P bidentate ligand and the minor isomer was identified as the elimination product. The naphthylamine auxiliary could be removed chemoselectively by treatment with concentrated hydrochloric acid. Optically pure As-P ligands containing the hydroxy groups at the chiral carbon centres were prepared by ligand displacement. The absolute configuration and coordination properties of the complexes have been established by single crystal X-ray analysis.

Full text of DOI:10.1016/j.jorganchem.2011.09.016

Journal of Organometallic Chemistry 696 (2012) 4215e4220
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Journal of Organometallic Chemistry
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Asymmetric hydroarsination reactions toward synthesis of alcohol functionalised
C-chiral AseP ligands promoted by chiral cyclometallated complexes
*
Yuen Lin Cheow, Sumod A. Pullarkat, Yongxin Li, Pak-Hing Leung
Division of Chemistry & Biological Chemistry, School of Physical & 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:
The asymmetric hydroarsination reactions between diphenylarsine and 3-diphenylphosphanyl-but-3-
en-1-ol and 2-diphenylphosphanyl-prop-2-en-1-ol have been achieved using the organopalladium
complex containing ortho-metallated (R)-[1-(dimethylamino)ethylnaphthalene as the chiral reaction
template in high stereoselectivities under mild conditions. Hydroarsination of 3-diphenylphosphanyl-
but-3-en-1-ol with diphenylarsine generated only one stereoisomer as five-membered AseP bidentate
chelate on chiral naphthylamine palladium template. Using the same chiral metal template, similar
hydroarsination reaction was carried out on 2-diphenylphosphanyl-prop-2-en-1-ol which gave two
different products in the ratio of 2.6 to 1. The major isomer was identified as the expected five-membered
AseP bidentate ligand and the minor isomer was identified as the elimination product. The naphthyl-
amine auxiliary could be removed chemoselectively by treatment with concentrated hydrochloric acid.
Optically pure AseP ligands containing the hydroxy groups at the chiral carbon centres were prepared by
ligand displacement. The absolute configuration and coordination properties of the complexes have been
established by single crystal X-ray analysis.
Received 19 July 2011
Received in revised form
15 September 2011
Accepted 21 September 2011
Keywords:
Allylic phosphine
Asymmetric hydroarsination
Chiral PeAs ligand
Palladacycle
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
functionalised AseP ligands promoted by chiral cyclometallated-
amine complexes of a hydroarsination reaction involving diphe-
Organoarsenic compounds are found to be useful in various
aspects of enantioselective catalysis. They have been found to be
more effective than phosphines in catalyzing a number of organic
reactions [1]. However available methods to prepare arsine ligands
are limited [2] and the number of reports on the addition of AseH
moiety to a CeC double bond of an unsaturated compound is not
vastly reported [3]. Applying chiral cyclometallated complexes as
efficient chiral auxiliaries, our group has recently published reports
on the synthesis of an optically active AseP heterobidentate ligand
via DielseAlder cycloaddition [4] and asymmetric hydroarsination
reaction [5]. Keto and ester- functionalised chiral pyridyl-arsines
has also been synthesised via a similar reaction by our group [6].
To our knowledge, no other example of metal complex activated
hydroarsination reactions involving diphenylarsine whereby
a series of chiral bidentate AseP ligands bearing diphenylphos-
phino moiety with chirality residing on carbon backbone carrying
various functional groups has been reported.
nylarsine
and
phosphine
functionalised
alkenols,
3-
diphenylphosphanyl-but-3-en-1-ol and 2-diphenylphosphanyl-
prop-2-en-1-ol. This work is part of our efforts to understand the
differences in P and As reactivity.
2. Results and discussion
2.1. Asymmetric hydroarsination of 3-diphenylphosphanyl-but-3-
en-1-ol
The monodentate 3-diphenylphosphanyl-but-3-en-1-ol was
coordinated to the palladium complex (Rc)-1 via a regiospecific
bridge splitting process (Scheme 1) [7]. It is known that the chloro
ligand in the template complex (Rc)-2a is kinetically and thermo-
dynamically stable and is not readily displaced by incoming mon-
odentate arsine ligands [8]. Therefore to provide an empty
coordination site for the incoming arsine ligand, complex (Rc)-2a
was treated with silver perchlorate.
The perchlorato complex (Rc)-3a was then treated with diphe-
nylarsine at ꢀ78 ꢁC and the reaction mixture was then left to stir for
24 h. The reported conditions are the optimum condition for this
reaction and have also been used extensively in our previous works
In continuation of our exploration of chiral AseP ligands, we
herein report a protocol for the synthesis of two chiral alcohol-
* Corresponding author. Tel.: þ65 63168905; fax: þ65 6 3166984.
E-mail address: pakhing@ntu.edu.sg (P.-H. Leung).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.09.016

4216
Y.L. Cheow et al. / Journal of Organometallic Chemistry 696 (2012) 4215e4220
N
N
Cl
Cl
P
R
Pd
Pd
PPh2
2
R
Ph
Ph
(Rc)-2a,b
(Rc)-1
a: R=CH2CH2OH
b: R=CH2OH
N
OClO3
Pd
Ph2AsH
MeOH
AgClO4
P
R
Ph
(Rc)-3a,b
Ph
Ph
Ph
Ph
Ph
Ph
Ph
N
N
N
As
P
As
P
As
+
+
+
H
H
R
Pd
Pd
Pd
P
R
- Ph
- Ph
- Ph
ClO4
Ph
Ph
Ph
ClO4
ClO4
(Rc)-6b : elimination
product for (Rc,Rc)-4b
(Rc,Sc)-5a,b
(Rc,Rc)-4a,b
Scheme 1. Chiral cyclometallated promoted asymmetric hydroarsination reactions of diphenylarsine and phosphine functionalised alkenols.
on asymmetric hydrophosphination [9] and hydroarsination reac-
tions [5]. The 31P NMR spectrum showed a singlet at
77.6 indi-
the dichloro complex with potassium cynanide at room tempera-
ture for ½ h. It is necessary to destroy the chiral template as there is
no other stronger chelating ligand suitable to displace the template
without destroying the structural integrity and stereochemistry of
the ligand other than potassium cyanides [4d,5]. The liberated
d
cating that only one diastereomer was generated out of the two
possible diastereomers. Unlike the addition of the analogous
secondary phosphine which resulted in cis-trans regioisomers of
the products [7,9], introduction of diphenylarsine in this reaction is
regiospecific. The P atom occupies the coordination site trans to the
N atom of the chiral auxiliary. Such high regioselectivity case has
been previously observed for other PeAs ligands [10]. The high
stereoselectivity has also been observed for the analogous hydro-
phosphination reactions. As described previously, the formation of
the favoured diastereomer is mainly due to steric factors [5e7]. The
crude mixture was then purified by column chromatography and
the product was obtained as a white solid in 55% isolated yield.
The single-crystal X-ray analysis of the crystallized pure product
(Rc,Rc)-4a showed that the expected five-membered PeAs biden-
tate ligand has been formed (Fig. 1). A new stereogenic centre at
C(28) was generated which adopts the R absolute configuration
while as expected the absolute configuration of the stereocentres at
C(11) remained unchanged. The geometry at the Pd centre is dis-
torted square planar with angle of 80.8(1)e100.2(1)ꢁ and 174.6(1)e
optically pure ligand (Rc)-8a [
tained as white solid in 88% yield (Scheme 2). The 31P NMR spec-
trum showed a singlet at
a
]
D
¼ þ62.3 (c 0.5, CH2Cl2) was ob-
d
ꢀ1.2 and the liberated ligand could be
recoordinated back to the same metal template without loss of
optical purity.
178.6(1)ꢁ (Table 1). The five-membered PeAs chelate adopts the
l
ring configuration with the CH2CH2OH substituent at C(28) occu-
pying an equatorial position [7.9g]. The P and As donor atoms of the
new heterobidentate are bonded regiospecifically to the metal
centre with the softer P atom occupying the position trans to NMe2
group Table 1.
Treatment with strong acid is a standard method to remove the
naphthylamine auxiliary. As shown in Scheme 2 the chiral naph-
thylamine in (Rc,Rc)-4a can be removed chemoselectively from the
palladium template by treatment with concentrated hydrochloric
acid in dichloromethane. The resultant neutral dichloro complex
(Rc)-7a was obtained as yellow prisms in 83% yield. The 31P NMR
spectum showed a singlet at
The optically active PeAs chiral bidentate (Rc)-8a could be
liberated from (Rc)-7a [
¼ ꢀ37.9 (c 0.5, CH2Cl2) by treatment of
d 77.5.
a]
Fig. 1. Molecular structure of complex (Rc,Rc)-4a.
D

Y.L. Cheow et al. / Journal of Organometallic Chemistry 696 (2012) 4215e4220
4217
Table 1
Selected bond lengths [Å] and angles [ꢁ] of (Rc,Rc)-4a.
Pd(1)eC(1)
Pd(1)eN(1)
Pd(1)eP(1)
Pd(1)eAs(1)
As(1)eC(15)
As(1)eC(21)
As(1)eC(27)
P(1)eC(28)
P(1)eC(31)
P(1)eC(37)
C(27)eC(28)
C(28)eC(29)
2.043(3)
2.132(2)
2.261(1)
2.443(1)
1.922(3)
1.940(3)
1.947(3)
1.885 (3)
1.818(3)
1.821(3)
1.535(5)
1.532(4)
C(1)ePd(1)eN(1)
C(1)ePd(1)eP(1)
N(1)ePd(1)eP(1)
C(1)ePd(1)eAs(1)
N(1)ePd(1)eAs(1)
P(1)ePd(1)eAs(1)
C(28)eP(1)ePd(1)
C(27)eAs(1)ePd(1)
C(29)eC(28)eC(27)
C(29)eC(28)eP(1)
C(28)eC(27)eAs(1)
C(27)eC(28)eP(1)
80.8 (1)
94.0(1)
174.6(1)
178.6(1)
100.2(1)
82.1(1)
112.4(1)
102.4(1)
111.2(3)
113.4(2)
110.1(1)
111.7(2)
2.2. Asymmetric hydroarsination of 2-diphenylphosphanyl-prop-2-
en-1-ol
The 2-diphenylphosphanyl-prop-2-en-1-ol ligand which was
obtained by hydrophosphination of propargyl alcohol [9g] was
coordinated to the dimeric ortho-metalled palladium complex (Rc)-
1 as shown in Scheme 1. The chloro complex (Rc)-2b was subse-
quently converted to the perchlorato complex by treatment with
aqueous silver perchlorate. The perchlorato complex (Rc)-3b was
dissolved in methanol and reacted with diphenylarsine at ꢀ78 ꢁC.
The 31P NMR spectrum showed two singlets at
d 66.3 and 55.6 in
Fig. 2. Molecular structure of complex (Rc,Rc)-4b.
the ratio of 2.6 to 1 respectively. The ratio of the two signals did not
change with different concentration of diphenylarsine. After puri-
fication by silica gel chromatography the major product (Rc,Rc)-4b
was crystallised from acetonitrile-diethyl ether as air-stable white
crystals.
The single crystal X-ray diffraction analysis of the complex
revealed that the expected five-membered PeAs bidendate chelate
has been formed (Fig. 2). A new stereogenic centre at C(28) was
generated which adopts the R absolute configuration while the
absolute configuration of the stereocentre at C(11) remained
unchanged. The geometry at the palladium is distorted square
planar with angle at palladium in the range 80.3(1)e103.0(1)ꢁ and
170.9(1)e174.6(1)ꢁ (Table 2). Similar to diastereomeric complex
(Rc,Rc)-4a in the five-membered PeAs bidentate chelate system the
CH2OH substituent at C(28) occupies an equatorial position [9a,9g].
The treatment of complex (Rc,Rc)-4b with concentrated hydro-
chloric acid generated (Rc)-7b (Scheme 2). The dichloro complex
was subsequently crystallised from dicholoromethane-dietyl-ether
as yellow prisms in 88% yield, [
treatment of (Rc)-7b with aqueous cyanide liberated the optically
pure (Rc)-8b in 79% yield, [
a]
¼ ꢀ120 (c 0.5, CH2Cl2). Further
D
a
]
¼ þ30 (c 0.3, CH2Cl2) (Scheme 2). The
D
recoordination of the free ligand to the metal template employing
the same protocol confirmed that (Rc)-8b is optically pure.
Ph
Ph
Ph
Ph
N
As
As
Cl
+
H
H
HCl
Pd
Pd
Cl
P
P
R
R
Ph
Ph
-
Ph
Ph
ClO4
(Rc)-7a,b
(Rc,Rc)-4a,b
Ph
Ph
Ph
Ph
As
P
As
Cl
Cl
KCN/H2O
H
R
H
R
Pd
P
Ph
Ph
Ph
Ph
(Rc)-8a,b
(Rc)-7a,b
Scheme 2. Liberation of optically active AseP ligands.

4218
Y.L. Cheow et al. / Journal of Organometallic Chemistry 696 (2012) 4215e4220
Table 2
Table 3
Selected bond lengths [Å] and angles [ꢁ] of (Rc,Rc)-4b
Selected bond lengths [Å] and angles [ꢁ] of (Rc)-6b
Pd(1)eC(1)
Pd(1)eN(1)
Pd(1)eP(1)
Pd(1)eAs(1)
As(1)eC(15)
As(1)eC(21)
As(1)eC(27)
P(1)eC(28)
P(1)eC(30)
P(1)eC(36)
C(27)eC(28)
C(28)eC(29)
2.031(3)
2.138(2)
2.253(1)
2.463(1)
1.950(3)
1.954(3)
1.980(3)
1.863 (3)
1.815(3)
1.818(3)
1.541(4)
1.523(4)
C(1)ePd(1)eN(1)
C(1)ePd(1)eP(1)
N(1)ePd(1)eP(1)
C(1)ePd(1)eAs(1)
N(1)ePd(1)eAs(1)
P(1)ePd(1)eAs(1)
C(28)eP(1)ePd(1)
C(27)eAs(1)ePd(1)
C(29)eC(28)eC(27)
C(29)eC(28)eP(1)
C(28)eC(27)eAs(1)
C(27)eC(28)eP(1)
80.3 (1)
94.9(1)
170.9(1)
174.6(1)
103.0(1)
82.4(1)
108.0(1)
105.1(1)
113.2(2)
113.0(2)
111.2(1)
108.2(2)
Pd(1)eC(1)
Pd(1)eN(1)
Pd(1)eP(1)
Pd(1)eAs(1)
As(1)eC(15)
As(1)eC(21)
As(1)eC(27)
P(1)eC(28)
P(1)eC(30)
P(1)eC(36)
C(27)eC(28)
C(28)eC(29)
2.046(6)
2.130(6)
2.247(1)
2.461(1)
1.940(8)
1.958(8)
1.940(8)
1.837 (8)
1.817(7)
1.825(7)
1.499(11)
1.347(12)
C(1)ePd(1)eN(1)
C(1)ePd(1)eP(1)
N(1)ePd(1)eP(1)
C(1)ePd(1)eAs(1)
N(1)ePd(1)eAs(1)
P(1)ePd(1)eAs(1)
C(28)eP(1)ePd(1)
C(27)eAs(1)ePd(1)
C(29)eC(28)eC(27)
C(29)eC(28)eP(1)
C(28)eC(27)eAs(1)
C(27)eC(28)eP(1)
80.3 (2)
95.0(2)
174.3(2)
177.5(2)
99.9(1)
84.9(5)
109.5(3)
104.6(2)
124.0(7)
122.8(6)
113.1(6)
104.6(2)
Table 4
Crystallographic data for complexes of (Rc,Rc)-4a, (Rc,Rc)-4b, (Rc)-6b.
The minor product isolated from silica gel chromatography was
crystallised from dichloromethane-diethyl ether. The single-crystal
X-ray diffraction revealed that it was (Rc)-6b (Fig. 3). The 31P NMR
(Rc,Rc)-4a (Rc,Rc)-4b (Rc)-6b
C43H46AsCl3NO5PPd C42.33H44AsNClO5PPd C41H40AsClNO4PPd
Formula
fw
Space group
spectrum showed a singlet at
d 55.6. The single-crystal X-ray
975.45
P2(1)2(1)2(1)
Crystal system Orthorhombic
903.87
P2(1)2(1)2(1)
Orthorhombic
16.3768(4)
21.2060(6)
33.9413(8)
90
858.48
P2(1)2(1)2(1)
Orthorhombic
8.8780(4)
12.7264(8)
35.0996(2)
90
crystallographic analysis clearly established that the hydroxyl
functional group has dissociated. The C28eC29 bond distance
[1.35(1) Å] is consistent with a typical CeC double bond (Table 3). A
possible explanation to the presence of the elimination product
could be found by analysing the structure of the coordination
complex (Rc)-2b. It was reported that upon coordination of the
vinylic phosphine entity to the metal template, crystallographic
data revealed that the oxygen atom of the eOH group was oriented
in such a way that in was in close proximity to the Pd metal centre
[9g]. This PdeO interaction can activate the OeC bond which then
underwent a cleavage assisted by the presence of uncoordinated
diphenylarsine. From the previous analogous hydrophosphination
reaction on 2-diphenylphosphanyl-prop-2-en-1-ol ligand, the
elimination product was not observed [9g]. This indicated the
presence of uncoordinated diphenylphosphine couldn’t assist the
OeC cleavage. Phosphines are softer than arsines and generally
show higher affinity to bind to the platinum metal ions than arsines
[13]. The reason why loss of H2O is not observed with phosphine is
because in the intermediate, the excess phosphine will approach all
possible coordination cites of the metal centre thus not allowing
oxygen to be chelated to the metal. Hence, no CeO activation can
a[Å]
b[Å]
10.0282(10)
18.8206(3)
22.8781(4)
90
c[Å]
a[ꢁ]
b[ꢁ]
90
90
90
g[ꢁ]
90
90
90
V[Å3]
4317.94(11)
4
11787.(5)
12
3792.1(4)
4
Z
T[K]
103(2)
1.501
103(2)
1.528
103(2)
1.504
Pcacld. [Mgmꢀ3
]
l
[Å]
[mmꢀ1
F(000)
0.71073
1.457
1984
0.71073
1.464
5528
0.71073
1.510
1744
m
]
Flack parameter 0.032(8)
0.002(4)
0.0740
0.1020
0.008(17)
0.0695
0.1410
R1(obsd. Data)a 0.0622
b
wR2
0.1234
P
P
a
R1
¼
jjF0j ꢀ jFcj= jF0jj.
qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
P
P
b
,wꢀ1 ¼ b2ðF02Þ þ (aP)2 þ bP.
2
2
2
wR2
¼
f
½wðF02 ꢀ Fc2Þ ꢂ= ½wðF0 Þ ꢂg
occur. However for arsine which is a harder donor than phosphine,
oxygen is allowed to bind to the metal centre and hence CeO
activation can occur.
When the hydroarsination reaction was carried out on 3-
diphenylphosphanyl-but-3-en-1-ol no elimination product was
observed and only the expected hydroarsination product was
present. This could be attributed to the longer chain length of
CH2CH2OH moiety for 3-diphenylphosphanyl-but-3-en-1-ol which
renders a weaker PdeO interaction.
3. Experimental
All air-sensitve manipulations were carried out using Schlenk
and cannula techniques under a positive pressure of purified
nitrogen. All NMR spectra were recorded at 25 ꢁC on Bruker Avance
300 and 500 spectrometer. Optical rotations were measure on the
specified solution in a 0.1 dm cell at 20 ꢁC with a PerkineElmer 341
polarimeter. Elemental analysis was performed by the Elemental
Analysis Laboratory of the Division of Chemistry and Biological
Chemistry at Nanyang Technological University. Melting points
were measured the SRS Optimelt Automated Melting Point System,
SRS MPA100. The enantiomerically pure of complexes (Rc)-1 [12], 3-
diphenylphosphanyl-but3-en-1-ol [9g] and 2-diphenylphosphanyl-
prop-2-en-1-ol [9g] were prepared as previously reported.
Caution! All perchlorate salts should be handled as potentially
explosive compounds. Care should be taken in handling highly toxic
arsine and cyanide compounds.
Fig. 3. Molecular structure of complex (Rc)-6b.

Y.L. Cheow et al. / Journal of Organometallic Chemistry 696 (2012) 4215e4220
4219
3.1. Hydroarsination reaction. Isolation of (R)-1-[1-
(dimethylamino)ethyl]-2napthyl-C,N][(R)-3-(diphenylphosphino)-
4-(diphenylarsino)butan-1-ol]palladium(II)] perchlorate (Rc,Rc)-4a
was filtered off using Celite. The solution was subsequently
washed with water (3 ꢃ 30 ml), and then the organic layer was
dried over magnesium sulphate. The solvent was removed and
the yellow solid was redissolved in methanol (100 ml). This
solution was treated with diphenylarsine (0.21 g, 0.00092 mols)
at ꢀ78 ꢁC. The temperature was maintained for 10 h then stirred
at room temperature for 24 h. The crude product was monitored
by 31P NMR until no more starting material was present. Two
A solution of the complex (Rc)-2a (0.5 g, 0.84 mmols) in
dichloromethane was treated with aqueous silver perchlorate
(0.4 g, 1.93 mmols) for 2 h. The white precipitate, silver chloride
was filtered off using Celite. The solution was subsequently
washed with water (3 ꢃ 30 ml), and then the organic layer was
dried over magnesium sulphate. The solvent was removed and
the yellow solid was redissolved in methanol (100 ml). This
solution was treated with diphenylarsine (0.19 g, 0.84 mmols)
at ꢀ78 ꢁC. The reaction mixture was then stirred for 24 h. The
crude product was monitored by 31P NMR until no more starting
material was present. Removal of solvent under reduced pressure
gave the crude products as a yellow solid. The crude product
mixture was then purified through a silica gel column with
dichloromethane/acetone as the eluent and then crystallised
from dichloromethane/hexane to give complex (Rc,Rc)-4a as
new signals were observed at
d 66.3 and 55.6 in the ratio of 2.6 to
1 respectively. Removal of solvent under reduced pressure gave
the crude products as a yellow solid. The crude product mixture
was then purified through a silica gel column with dichloro-
methane/acetone as the eluent. The major isomer was then
crystallised from acetonitrile- diethyl ether to give complex
(Rc,Rc)-4b as white crystals; (0.18 g, 25% yield); m.p. 203e204 ꢁC
(decomp.), [
a
]
¼ ꢀ116 (c 0.3, CH2Cl2). C41H42ClNO5PAsPd:calcd. C
D
56.2, N 1.6 H 4.8. Found: 56.4, N 1.7, H 4.6. 31P{1H} NMR (CDCl3,
3
d
): 66.3. 1H NMR (CDCl3,
d
): 2.12 (d, 3H, JHH ¼ 6.2 Hz, CHMe),
2.85 (s, 3H, NMe), 2.95 (s, 3H, NMe), 3.05 (1H, m, Ph2PCHCH2),
3.50 (m, 2H, CH2OH), 3.69 (m, 1H, Ph2AsCH’HCH), 3.91 (m, 1H,
white crystals; m.p. 210e211 ꢁC (decomp.), [
CH2Cl2); 0.411g (55% yield). C42H44ClNO5PAsPd:calcd. C 56.6, H
4.9, N 1.6. Found: C 56.4, H 4.8, N 1.5. 31P{1H} NMR (CDCl3,
):
77.6. 1H NMR (CDCl3,
): 1.26 (m, 1H, Ph2AsCH’HCH), 1.47 (m, 1H,
a]
¼ þ92.0 (c 0.7,
D
3
Ph2AsCH’HCH), 4.46 (qn, 1H, JHH ¼ 6.1 Hz, CHMe), 6.72e8.26 (m,
d
26H, aromatics).
d
3
Ph2AsCH’HCH), 2.01(1H, m, PCHCH2), 2.19 (d, 3H, JHH ¼ 6.4 Hz,
3.5. Dichloro[(R)-3-(diphenylphosphino)-4-(diphenylarsino)
propan-1-ol]palladium(II) (Rc)-7b
CHMe), 2.54 (s, 3H, NMe), 2.86 (m, 2H, CH2CH2OH), 2.93 (m, 2H,
3
CH2CH2OH) 2.95 (s, 3H, NMe), 3.70 (t, 1H, JHH ¼ 6.7 Hz, OH),
3
4.62 (qn, 1H, JHH
aromatics).
¼
6.1 Hz, CHMe), 6.75e8.43 (m, 26H,
A solution of the complex (Rc,Rc)-4b (0.1 g, 0.13 mmols) in
dichloromethane was stirred with concentrated hydrochloric acid
(5 mL) for 16 h. The excess acid was then removed by washing with
water (3 ꢃ 20 mL) and the organic layer was dried using mage-
nesium sulphate. Upon removal of the solvent, a pale yellow solid
was obtained (0.066 g, 79% yield); m.p. 213e214 ꢁC (decomp.),
3.2. Dichloro[(R)-3-(diphenylphosphino)-4-(diphenylarsino)butan-
1-ol]palladium(II) (Rc)-7a
A solution of the complex (Rc,Rc)-4a (0.2 g, 0.22 mmols) in
dichloromethane was stirred with concentrated hydrochloric acid
(5 mL) for 16 h. The excess acid was then removed by washing with
water (3 ꢃ 20 mL) and the organic layer was dried using mage-
nesium sulphate. Upon removal of the solvent, a pale yellow solid
was obtained (0.12 g, 83% yield); m.p. 223e224 ꢁC (decomp.),
[a
]
D
¼ ꢀ120 (c 0.5, CH2Cl2). C27H26Cl2OPAsPd:calcd. C 49.9, H 4.0.
Found: 50.3, H 4.2. 31P{1H} NMR (CDCl3, ): 70.0. 1H NMR (CDCl3,
d d):
2.40e2.78 (2H, m, Ph2AsCH2CH), 3.32 (m, 2H, CH2OH), 3.63 (m, 1H,
Ph2PCHCH2), 7.30e7.56 (m, 20H, aromatics).
[
a
]
¼ ꢀ37.9 (c 0.5, CH2Cl2). C28H28Cl2OPAsPd:calcd. C 50.6, H 4.2.
D
3.6. Decomplexation of [(R)-3-(diphenylphosphino)-4-
(diphenylarsino)propan-1-ol, (Rc)-8b
Found: 50.4, H 4.0. 31P{1H} NMR (CDCl3, ): 77.5. 1H NMR (CDCl3,
d d):
1.21 (m, 1H, Ph2AsCH’HCH), 1.56 (m, 1H, Ph2AsCH’HCH), 1.76 (1H, m,
PCHCH2), 3.20 (m, 2H, CH2CH2OH), 3.50 (m, 2H, CH2CH2OH),
7.28e7.36 (20H, m, aromatics).
A solution of the complex (Rc)-7b (0.05 g, 0.077 mmols) in
dichloromethane was stirred vigorously with aqueous potassium
cyanide (0.3 g) for 30 min. The resulting colourless organic layer
was separated, washed with water and dried (MgSO4). Upon the
3.3. Decomplexation of [(R)-3-(diphenylphosphino)-4-
(diphenylarsino)butan-1-ol], (Rc)-8a
removal of solvent, a white solid (Rc)-8b was obtained, [
a
]
¼ þ30
D
(c 0.3, CH2Cl2); 0.033 g (90% yield). 31P{1H} NMR (CDCl3,
d
): ꢀ9.0 1H
NMR (CDCl3,
d
): 2.19 (d, 2H, 3JHH ¼ 7.7 Hz, Ph2AsCH2CH), 2.61 (1H,
A solution of the complex (Rc)-7a (0.10 g, 0.15 mmols) in
dichloromethane was stirred vigorously with aqueous potassium
cyanide (0.3 g) for 30 min. The resulting colourless organic layer
was separated, washed with water and dried (MgSO4). Upon the
m, PCHCH2), 3.72e3.95 (m, 2H, CH2OH), 7.28e7.38 (m, 20H,
aromatics).
removal of solvent,
a white solid (Rc)-8a was obtained,
[
a]
¼ ꢀ37.9 (c 0.5, CH2Cl2); 0.065 g (88% yield). 31P{1H} NMR
3.7. Hydroarsination reaction isolation of (R)-1-[1-
(dimethylamino)ethyl]-2-napthyl-C,N][(R)-3-(diphenylphosphino)-
4-(diphenylarsino)prop-1-ene]palladium(II) perchlorate (Rc)-6b
D
(CDCl3,
d
): ꢀ1.2. 1H NMR (CDCl3,
d): 1.28 (m, 1H, Ph2AsCH’HCH),
1.88 (m, 1H, Ph2AsCH’HCH), 1.92 (1H, m, PCHCH2), 2.57 (m, 2H,
CH2CH2OH), 3.70 (m, 2H, CH2CH2OH), 7.28e7.36 (20H, m,
aromatics).
Purification from silica column chromatography followed by
crystallisation from dichloromethane-diethyl ether gave the minor
product (Rc)-10 as white crystals; (0.12 g, 15% yield); m.p.
203e204 ꢁC (decomp.), C41H40ClNO4PAsPd:calcd. C 57.3, N 1.6 H 4.7.
3.4. Hydroarsination reaction isolation of (R)-1-[1-
(dimethylamino)ethyl]-2-napthyl-C,N][(R)-3-(diphenylphosphino)-
4-(diphenylarsino)propan-1-ol]palladium(II) perchlorate (Rc,Rc)-4b
Found: 57.4, N 1.7, H 4.6. 31P{1H} NMR (CDCl3, ): 55.6. 1H NMR
d
(CDCl3,
d
): 1.97 (d, 3H, 3JHH ¼ 6.1 Hz, CHMe), 2.84 (s, 6H, NMe2), 3.25
3
A solution of the complex (Rc)-2b (0.53 g, 0.92 mmols) in
dichloromethane was treated with aqueous silver perchlorate
(0.57 g, 2.76 mmols) for 2 h. The white precipitate, silver chloride
(2H, m, AsCH2C), 4.64 (qn, 1H, JHH ¼ 6.1 Hz, CHMe), 5.07 (d, 1H,
2JHH ¼ 2.1 Hz C]CH’H), 5.77 ( 1H, JHH ¼ 2.1 Hz C]CH’H), 6.76e8.05
2
(m, 26H, aromatics)

4220
Y.L. Cheow et al. / Journal of Organometallic Chemistry 696 (2012) 4215e4220
(e) R.A. Baber, S. Collard, M. Hooper, A.G. Orpen, P.G. Pringle, M.J. Wilkinson,
R.L. Wingad, Dalton Trans. (2005) 1491e1498;
(f) S. Ceccarelli, U. Piarulli, C. Gennari, J. Org. Chem. 65 (2000) 6254e6256;
(g) L.A. Van der Veen, P.K. Keeven, P.C. Kamer, P.W.N.M. Van Leeuwen, Chem.
Commun. (2000) 333e334;
3.8. X-ray crystal structure determinations of complexes (Rc,Rc)-
4a, (Rc,Rc)-4b and (Rc)-6b
Crystal data and a summary of the crystallographic analyses are
given in Table 4. Diffraction data were collected on a Bruker X8 CCD
(h) J.A. Casares, P. Espinet, G. Salas, Organometallics 27 (2008) 3761e3769.
[2] F.Y. Kwong, C.W. Lai, K.S. Chan, J. Am. Chem. Soc. 123 (2001) 8864e8865.
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3640e3643;
diffractometer with Mo K
a radiation (graphite monochromator).
SADABS absorption corrections were applied. All non-hydrogen
atoms were refined anisotropically, while the hydrogen atoms
were introduced at calculated positions and refined riding on their
carrier atoms. The absolute configurations of the chiral complexes
were determined unambiguously by using the Flack parameter
[11].
(b) M. Ma, S.A. Pullarkat, Y. Li, P.H. Leung, Inorg. Chem. 46 (2007) 9488e9494;
(c) M. Ma, R. Lu, S.A. Pullarkat, W. Deng, P.H. Leung, Dalton Trans. 39 (2010)
5453e5461;
(d) M. Ma, S.A. Pullarkat, M. Yuan, N., Zhang, Y. Li, P.H. Leung, Organometallics
28 (2009) 4886e4889.
[5] M.L. Bungabong, K.W. Tan, Y. Li, S.V. Selvaratnam, K.G. Dongol, P.H. Leung,
Inorg. Chem. 46 (2007) 4733e4736.
Acknowledgement
[6] F. Liu, S.A. Pullarkat, Y. Li, S. Chen, P.H. Leung, Eur. J. Inorg. Chem. (2009)
4134e4140.
[7] W.C. Yeo, S.Y. Tee, H.B. Tan, G.K. Tan, L. L Koh, P.H. Leung, Inorg. Chem. 43
(2004) 8102e8109.
[8] P.H. Leung, Acc. Chem. Res. 37 (2004) 169e177.
[9] (a) S. Chen, J.K.P. Ng, S.A. Pullarkat, F. Liu, Y. Li, P.H. Leung, Organometallics 29
(2010) 3374e3386;
We thank Nanyang Technological University for support of this
research and PhD scholarship to Y. L.C.
Appendix A. Supplementary material
(b) M. Yuan, N. Zhang, S.A. Pullarkat, Y. Li, F. Liu, P.T. Pham, P.H. Leung, Inorg.
Chem. 49 (2010) 989e996;
(c) Y. Huang, S.A. Pullarkat, M. Yuan, Y. Ding, Y. Li, P.H. Leung, Organometallics
29 (2010) 536e542;
(d) M. Yuan, S.A. Pullarkat, Y. Li, Z.Y. Lee, P.H. Leung, Organometallics 29
(2010) 3582e3588;
(e) M. Yuan, S.A. Pullarkat, M. Ma, Y. Zhang, Y. Huang, Y. Li, A. Goel, P.H. Leung,
Organometallics 28 (2009) 780e786;
(f) Y. Zhang, S.A. Pullarkat, Y. Li, P.H. Leung, Inorg. Chem. 48 (2009)
5535e5539;
CCDC-815920 [for (Rc,Rc)-4a], ꢀ815921 [for (Rc,Rc)-4b], ꢀ815922
[for (Rc)-6; contains the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/
cif.
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