Novel enantioselective synthesis of functionalized pyridylarsanes by a chiral palladium template promoted asymmetric hydroarsanation reaction

Article abstract of DOI:10.1002/ejic.200900460

The asymmetric hydroarsanation reactions between diphenylarsane and (E)-l-phenyl-3-(pyridin-2-yl)-2-propenone and (E)-l-methyl-3-(pyridin-2-yl)-2- propenoate have been achieved by use of the organopalladium complex containing ortho-metalated (R)-[1-(dimet

Full text of DOI:10.1002/ejic.200900460

FULL PAPER
DOI: 10.1002/ejic.200900460
Novel Enantioselective Synthesis of Functionalized Pyridylarsanes by a Chiral
Palladium Template Promoted Asymmetric Hydroarsanation Reaction
Fengli Liu,[a] Sumod A. Pullarkat,[a] Yongxin Li,[a] Shuli Chen,[a] and Pak-Hing Leung*[a]
Keywords: Asymmetric synthesis / Palladium / As ligands / Template synthesis
The asymmetric hydroarsanation reactions between di-
phenylarsane and (E)-1-phenyl-3-(pyridin-2-yl)-2-propenone
and (E)-1-methyl-3-(pyridin-2-yl)-2-propenoate have been
achieved by use of the organopalladium complex containing
ortho-metalated (R)-[1-(dimethylamino)ethyl]naphthalene as
the chiral reaction template in high regio- and stereoselecti-
vities under mild conditions. Hydroarsanation of (E)-1-
product as a six-membered As–N bidentate chelate. The
naphthylamine auxiliary could be removed chemoselectively
by treatment with concentrated hydrochloric acid to form the
corresponding optically pure neutral complexes. Subsequent
ligands displacement from the palladium using aqueous po-
tassium cyanide generated the optically pure keto- and ester-
functionalized chiral pyridylarsane ligands. The absolute
phenyl-3-(pyridin-2-yl)-2-propenone with diphenylarsane configuration and the coordination properties of the pyr-
generated two stereoisomeric products in the ratio of 3:1 as
five-membered As–N bidentate chelates on the chiral naph-
thylamine palladium template. Using the same chiral metal
template, the corresponding hydroarsanation reaction with
(E)-1-methyl-3-(pyridin-2-yl)-2-propenoate gave only one
idylarsanes have been established by single-crystal X-ray
analysis.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
chiral pyridylphosphanes have been reported. In this paper,
we report an efficient approach for the enantioselective syn-
thesis of keto- and ester-functionalized chiral pyridyl-
arsanes via the asymmetric hydroarsanation reaction in which
the chiral organopalladium complex (R)-1 is used as both
the reaction promoter and the stereochemical controller.
Introduction
Recently, organoarsenic compounds have been found to
play important roles in many aspects of organic synthesis
and catalytic reactions. Tertiary arsanes have been reported
to be more appropriate ligands than phosphanes in a
number of transition metal-catalyzed organic reactions, for
example, Stille[1] and Heck reactions,[2] hydroformylation,[3]
Suzuki–Miyaura coupling reaction,[4] carbonylation,[5] nor-
bornene polymerization[6] and Wittig-type olefination of al-
dehydes.[7] Although several chiral arsane compounds have
been used in asymmetric catalytic reactions,[8] these earlier
studies have not involved optically active pyridylarsanes,
which would provide a variety of applications in asymmet-
ric catalysis as shown by their phosphorus analogues.[9]
However, most available arsanation protocols are limited to
compounds that are not base and reducible agent sensi-
tive[10] and devoid of functionalities. The only straightfor-
ward method for synthesis of functionalized arsanes has
been recently reported,[11] Pd-catalyzed arsanation of aryl
triflates using triphenylarsane as the arsanating agent.
However via that methodology, heteroatom-substituted
pyridyl triflates did not react at all. Until now, no synthesis
of enantiomerically pure keto- and ester-substituted C-
Results and Discussion
Asymmetric Hydroarsanation of (E)-1-Phenyl-3-(pyridin-2-
yl)-2-propenone
In the absence of a metal ion, diphenylarsane shows no
reactivity with (E)-1-phenyl-3-(pyridin-2-yl)-2-propenone
(2). However, as illustrated in Scheme 1, in the presence of
chiral complex (R)-1, The reaction is completed in 12 d at
room temperature to give a 3:1 diastereomeric mixture of
(RC,RC)-3 and (RC,SC)-3.
While the addition of the secondary phosphane to vinylic
phosphanes resulted in cis/trans regioisomeric products,[12]
the addition of diphenylarsane to vinylic pyridines is 100%
regioselective, wherein the As atom occupies the coordina-
tion site trans to the N atom. The high regioselectivity ob-
served in the present case is in agreement with what has
been observed for similar N–P heterobidentate ligands.[13]
The diastereomeric products were subsequently separated
by column chromatography. The major diastereomer
(RC,RC)-3 was obtained as a pale yellow solid in 30% iso-
lated yield. Although it is stable in the solid state and in
[a] Division of Chemistry & Biological Chemistry, School of
Physical & Mathematical Sciences, Nanyang Technological
University,
Singapore 637371, Singapore
E-mail: pakhing@ntu.edu.sg
4134
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 4134–4140

Chiral Asymmetric Hydroarsanation
Scheme 1.
solution, it is highly soluble in most organic solvents and
could not be induced to crystallize. Upon subsequent treat-
ment of the perchlorate salt with concentrated hydrochlorc
acid, the resultant neutral dichloro complex (R)-4 was ob-
tained as yellow prisms in 87% isolated yield, [α]D = –122
(c = 0.6, CH2Cl2) (Scheme 2). The chelating properties and
the absolute configuration of the coordinated pyridine-sub-
stituted arsane ligand in complex (R)-4 were studied by X-
ray crystallography (Figure 1). Selected bond lengths and
angles of the complex are given in Table 1. The structure
analysis established that the newly formed stereogenic cen-
ter at C(6) adopted the R absolute configuration. The ge-
ometry at the Pd center is distorted square planner with
angles of 84.3(1)–92.8(1) and 171.0(1)–179.3(1)°. Both the
Pd–As and Pd–N bond lengths, 2.278(1) and 2.071(2) Å,
are typical, but the two Pd–Cl distances 2.305(1) and
2.376(1) Å differ significantly, with the bond trans to the
As being noticeably larger than the bond trans to the N.
This reflects the stronger electronic trans effect of the As
relative to the aromatic nitrogen donor. The C(6)–C(7)
bond length [1.536(4) Å] showed marked lengthening,
which is clearly attributed to the intrachelate repulsive inter-
actions between the COPh moiety at C(7) and the phenyl
groups on the As donor atom. The CH2COPh substituent
of the five-membered Pd–N chelate is in the preferred equa-
torial disposition.[14] The bond length of Pd–As in (R)-4
Figure 1. Molecular structure of the dichloro complex (R)-4.
Table 1. Selected bond lengths [Å] and angles [°] for (R)-4.
Pd(1)–N(1)
Pd(1)–Cl(2)
C(1)–N(1)
C(6)–As(1)
C(6)–C(7)
2.071(2)
2.305 (1)
1.341(4)
1.971(3)
1.536(4)
Pd(1)–As(1)
Pd(1)–Cl(1)
C(5)–N(1)
C(8)–O(1)
2.278 (1)
2.376 (1)
1.368(3)
1.216(4)
1.510(4)
171.0(1)
96.1(1)
C(5)–C(6)
N(1)–Pd(1)–As(1) 84.3(1)
As(1)–Pd(1)–Cl(2) 86.7(1)
N(1)–Pd(1)–Cl(2)
N(1)–Pd(1)–Cl(1)
N(1)–C(5)–C(6)
C(4)–C(5)–C(6)
C(5)–C(6)–As(1)
C(8)–C(7)–C(6)
C(5)–N(1)–Pd(1)
[2.278(1) Å] is longer than that of the corresponding Pd–P As(1)–Pd(1)–Cl(1) 179.3(1)
120.8(2)
118.7(2)
108.7(2)
113.8(2)
118.6(2)
[2.184(4) Å],[13] which is in agreement with the 0.10–0.11 Å
Cl(2)–Pd(1)–Cl(1) 92.8(1)
C(5)–C(6)–C(7)
C(7)–C(6)–As(1)
C(1)–N(1)–C(5)
C(6)–As(1)–Pd(1)
114.4(2)
112.8(2)
118.1(2)
102.3(1)
difference in the covalent bond radii of As (1.21 Å) and P
(1.10 Å).[15]
The liberation of the free As–N ligand (R)-5 was
achieved by the treatment of the dichloro complex with
aqueous potassium cyanide (Scheme 3). Thus the pyridylar-
sane was obtained as a white solid in 75% yield, [α]D
=
+78 (c = 0.4, CH2Cl2). Because of the air-sensitivity of the
noncoordinated As atoms, liberated (R)-5 was not stored in
its pure form but was recoordinated again to (R)-1. The
recoordination process is also a means of verifying the op-
Scheme 2.
Eur. J. Inorg. Chem. 2009, 4134–4140
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4135

F. Liu, S. A. Pullarkat, Y. Li, S. Chen, P.-H. Leung
FULL PAPER
tical purity of the released ligand to establish the identity chromatography, the product (RC,SC)-7 was subsequently
of the minor isomers that were generated in the original crystallized from dichloromethane/diethyl ether as pale yel-
hydroarsanation reaction.[16,12] The recoordination pro- low prisms in 51% yield, [α]D = –77 (c = 0.6, CH2Cl2).
cedure was monitored by 1H NMR spectroscopy. In CDCl3,
the 1H NMR spectrum of the recoordination product
showed only one product, thus confirming that the liber-
ated (R)-5 is optically pure.
Scheme 4.
The X-ray crystallographic analysis of the complex con-
firmed that an enantiomerically pure product has been
formed in which the six-membered As–N chelate coordi-
nated to palladium as a bidentate chelate (Figure 2) with a
twist-boat conformation. Furthermore, the structure analy-
sis unambiguously established that the newly formed
stereogenic center at C(21) adopts the S configuration. The
As and N donor atoms of the new heterobidentate ligand
are bonded regiospecifically to the Pd atom, with the softer
As donor expectedly taking up the position trans to the
NMe2 group. Selected bond lengths and angles are listed in
Scheme 3.
Table 2. The angles formed by the As–N chelate and the
In order to establish the identity of the minor product
naphthylamine template at the Pd metal center were in the
that was formed from hydroarsanation reaction, (R)-5 was
range of 81.0(2)–97.8(2) and 169.6(1)–171.6(2)°. The C(21)–
recoordinated regiospecifically to (SC)-1 to generate the dia-
stereomeric complex (SC,RC)-3 (Scheme 3). The H NMR
spectrum of the complex (SC,RC)-3 was identical with those
observed from the minor product generated from the hy-
As(1) and C(20)–C(21) distances [2.002(5) and 1.533(7) Å]
are elongated noticeably by the intrachelate interactions.
1
The bond length of Pd–As in (RC,SC)-7 [2.345(1) Å] is also
longer than that of the corresponding Pd–P [2.239(1) Å].[13]
droarsanation reaction. Hence it could be confirmed that
complex (RC,SC)-3 is the minor product in the original hy-
1
droarsanation reaction. No H NMR signals could be de-
tected for the major diastereomer thus reaffirming that lib-
erated (R)-5 is enantiomerically pure.
Asymmetric Hydroarsanation of (E)-1-Methyl-3-(pyridin-2-
yl)-2-propenoate
In principle, the hydroarsanation reaction between (E)-
1-methyl-3-(pyridin-2-yl)-2-propenoate and Ph2AsH should
generate similar five-membered As–N chelate products as
that obtained from the reaction involving (E)-1-phenyl-3-
(pyridinyl-2-yl)-2-propenone (6). Interestingly, after 14 d at
room temperature the chelating As–N complex (RC,SC)-7
was generated as the sole product in the hydroarsanation
reaction (Scheme 4). After purification by column Figure 2. Molecular structure of the cationic complex (RC,SC)-7.
4136
www.eurjic.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 4134–4140

Chiral Asymmetric Hydroarsanation
Table 2. Selected bond lengths [Å] and angles [°] for (RC,SC)-7.
Conclusions
Pd(1)–C(1)
Pd(1)–N(2)
C(15)–N(2)
1.994(5)
2.168(4)
1.348(6)
1.505(7)
2.002(5)
1.334(7)
81.0(2)
Pd(1)–N(1)
Pd(1)–As(1)
C(19)–N(2)
C(20)–C(21)
C(22)–O(1)
C(30)–As(1)
C(1)–Pd(1)–N(2)
C(1)–Pd(1)–As(1)
N(2)–Pd(1)–As(1)
C(19)–C(20)–C(21) 111.0(4)
C(22)–C(21)–As(1) 110.6(3)
C(15)–N(2)–C(19) 118.5(4)
C(21)–As(1)–Pd(1) 106.4(1)
2.123(4)
2.345(1)
1.346(6)
1.533(7)
1.195(6)
1.938(4)
171.6(2)
94.9(1)
From a mechanistic standpoint, we believe that the
mechanism involved in the asymmetric hydroarsanation is
similar to that of hydrophosphanation.[17] The simultaneous
coordination of diphenylarsane and pyridine complex on
the chiral palladium template polarized the As–H and vin-
ylic C=C bonds concurrently. An intermediate involving
the deprotonated form of the highly reactive coordinated
arsenido ligand could thus be generated in the presence of
excess pyridine complex. This nucleophilic arsenido moiety
subsequently undergoes addition to the activated alkene. A
correlation between the X-ray crystallography data of the
hydroarsanation product and a Dreiding model study con-
firmed that the formation of the As–Pd–N six-membered
ring would markedly relieve the interchelate repulsive inter-
actions than a five-membered ring. Therefore the formation
of the six-membered ring between (E)-1-methyl-3-(pyridin-
2-yl)-2-propenoate and Ph2AsH must be due to the pre-
dominant steric factors. The X-ray crystallographic analysis
of (RC,SC)-7 revealed that the CO2Me group at C(21) occu-
pies the sterically favorable equatorial position in the twist
boat conformation (Figure 3).[14] The 6-H of the pyridine
ring is far away from the two NMe group and there should
not be any significant steric repulsion. In addition, less ste-
ric repulsion exists between the naphthylene proton Hγ and
the quasi-axial phenyl group on As.[18] However model
studies shows that in (RC,RC)-7, the CO2Me group occupies
the sterically unfavorable axial position. Although the 6-H
of the pyridine ring is far away from to the two NMe
groups, there is still significant steric repulsion between the
naphthylene proton Hγ and the quasi-equatorial phenyl
group on As. We believe that these interchelate repulsive
forces are the discriminating factors that hinder the forma-
tion of the unfavored diastereomer.
C(19)–C(20)
C(21)–As(1)
C(22)–O(2)
C(1)–Pd(1)–N(1)
N(1)–Pd(1)–N(2)
N(1)–Pd(1)–As(1) 169.6(1)
N(2)–C(19)–C(20) 117.1(4)
C(22)–C(21)–C(20) 110.9(4)
C(20)–C(21)–As(1) 110.0(3)
C(19)–N(2)–Pd(1) 124.7(3)
97.8(2)
87.6(1)
The treatment of complex (RC,SC)-7 with concentrated
hydrochloric acid generated (S)-8 (Scheme 5). The dichloro
complex was subsequently crystallized from dichlorometh-
ane/diethyl ether as yellow prisms in 91% yield, [α]D = –113
(c = 0.6, CH2Cl2). Further treatment of (S)-8 with aqueous
cyanide liberated the optically pure (S)-9 as pale yellow so-
lid in 80% yields, [α]D = –102 (c = 1.0, CH2Cl2). The reco-
ordination of the free ligand to (R)- and (S)-1 employing
the same protocol used for (R)-5 confirmed that (S)-9 is
optically pure.
Scheme 5.
Figure 3. Interchelate interactions in (RC,SC)-7 and (RC,RC)-7.
Eur. J. Inorg. Chem. 2009, 4134–4140
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4137

F. Liu, S. A. Pullarkat, Y. Li, S. Chen, P.-H. Leung
FULL PAPER
Figure 4. Interchelate interactions in (RC,RC)-3 and (RC,SC)-3.
methyl (E)-1-methyl-3-(pyridin-2-yl)-2-propenoate[21] were pre-
pared as previously reported.
The formation of the five-membered ring between (E)-1-
phenyl-3-(pyridin-2-yl)-2-propenone and Ph2AsH is be-
cause there are more severe interchelate steric constrains
within phenyl groups of Ph2As and COPh in the six-mumb-
ered ring. The model studies clearly indicate that in the
major isomer (RC,RC)-3, the COPh group at C(6) of the
five-membered As–Pd–N chelate occupies the sterically fa-
vorable equatorial position (Figure 4). In this molecule,
however, the 6-H of the pyridine ring unfavorably oriented
towards the NMe group which is in the equatorial position.
In the minor isomer (RC,SC)-3, the COPh group occupies
the sterically unfavorable axial position. In addition, the 6-
H of the pyridine ring intrudes into the space between the
two methyl groups on N to achieve the least steric repulsion
state. Similar driving forces are present in the case of the
analogue P–N ligands.
In conclusion, the efficient synthesis of keto- and ester-
functionalized chiral pyridylarsanes via chiral organopalla-
dium template promoted asymmetric hydroarsanation has
been demonstrated. The hydroarsanation reactions proceed
with high regio- and stereoselectivities under mild condi-
tions. Further investigations on the catalytic properties of
transition metal complexes containing these optically active
ligands are currently in progress.
Dichloro-[(R)-1-phenyl-3-(diphenylarsanyl)-3-(pyridin-2-yl)propan-
one-(N1,As2)]palladium(II) [(R)-4]: The bis(acetonitrile)Pd complex
(R)-1 (1 g, 2.05 mmol) in dichloromethane (40 mL) was treated
with (E)-1-phenyl-3-(pyridin-2-yl)-2-propenone (0.473 g,
2.26 mmol) and Ph2AsH (0.473 g, 2.05 mmol) at room temperature
for 12 d. 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 crystallized from dichloromethane/diethyl
ether to give the complex (RC,RC)-3 as pale yellow glass (0.52 g,
30% yield) that could not be crystallized from any of the solvents
tried. The cationic complex (0.50 g, 0.593 mmol) in dichlorometh-
ane (30 mL) was treated with concentrated hydrochloric acid
(12 mL) for 1 h at room temperature. The reaction mixture was
then washed with water (4 ϫ 10 mL) and dried (MgSO4). Sub-
sequently fractional recrystallization from dichloromethane/diethyl
ether gave complex (R)-4 as yellow prisms; m.p. 207–208 °C (de-
comp.), [α]D = –122 (c = 0.6, CH2Cl2); 0.318 g (87 % yield).
C26H22AsCl2NOPd (616.7): calcd. C 50.6, H 3.6, N 2.3; found C
1
2
50.6, H 4.0, N 2.0. H NMR (CD2Cl2): δ = 3.57 (dd, JH,H = 18.6,
3JH,H = 5.6 Hz, 1 H, CHaHb), 3.87 (dd, JH,H = 18.6, JH,H
8.0 Hz, 1 H, CHaHb), 5.14 (dd, JH,H = 5.6, JH,H = 8.0 Hz, 1 H,
Hc), 7.30–8.02 (m, 18 H, aromatics), 9.81 (d, JH,H = 5.9 Hz, 1 H,
=
2
3
3
3
3
Hd) ppm.
Experimental Section
General: Reactions involving air-sensitive compounds were per-
formed under an inert atmosphere of argon using standard Schlenk
techniques. NMR spectra were recorded at 25 °C on Bruker Avance
400 spectrometer. Optical rotations were measured on the specified
solution in a 0.1 dm cell at 20 °C with a Perkin–Elmer 341 polari-
meter. Elemental analysis was performed by the Elemental Analysis
Laboratory of the Division of Chemistry and Biological Chemistry
at Nanyang Technological University. Melting points were mea-
sured using the SRS Optimelt Automated Melting Point System,
SRS MPA100. The enantiomerically pure forms of the complexes
(Rc)-1, (Sc)-1,[19] (E)-1-phenyl-3-(pyridin-2-yl)-2-propenone,[20] and
(R)-1-Phenyl-3-(diphenylarsanyl)-3-(pyridin-2-yl)propanone [(R)-5]:
A solution of (R)-4 (0.0617 g, 0.1 mmol) in dichloromethane
(15 mL) was stirred vigorously with a saturated aqueous solution
of potassium cyanide (0.2 g) for 5 min. The resulting colorless or-
ganic layer was separated, washed with water, and dried (MgSO4).
4138
www.eurjic.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 4134–4140

Chiral Asymmetric Hydroarsanation
Upon the removal of solvent, a white solid (R)-5 was obtained, [α]D
was stirred vigorously with a saturated aqueous solution of potas-
sium cyanide (0.2 g) for 5 min. The resulting colorless organic layer
= +78 (c = 0.4, CH2Cl2); 0.033 g (75% yield). 1H NMR (CD2Cl2): δ
3
= 3.23 (d, JH,H = 16 Hz, 1 H, CHaHb), 4.30–4.41 (m, 2 H, Hc + was separated, washed with water, and dried (MgSO4). Upon the
3
CHaHb), 6.84–7.88 (m, 18 H, aromatics), 8.48 (d, JH,H = 4.6 Hz, removal of solvent, a white solid (S)-9 was obtained, [α]D = –102
1 H, Hd) ppm.
(c = 1.0, CH2Cl2); 0.031 g (80% yield). 1H NMR (CD2Cl2): δ =
3
2
3.13 (dd, JH,H = 14.8, JH,H = 4.7 Hz, 1 H, Ha), 3.22 (s, 3 H,
COOCH3), 3.47 (dd, 3JH,H = 14.8, JH,H = 10.9 Hz, 1 H, Hc), 3.93
(dd, JH,H = 10.9, JH,H = 4.7 Hz, 1 H, Hb), 7.07–7.63 (m, 14 H,
aromatics), 8.49 (d, JH,H = 4.5 Hz, 1 H, Hd) ppm.
3
3
2
3
{(R)-1-[1-(Dimethylamino)ethyl]naphthyl-(C2,N)}[(S)-methyl-2-(di-
phenylarsanyl)-3-(pyridin-2-yl)propanoate-(N1,As2)]palladium(II)
Perchlorate [(RC,SC)-7]:. The bis(acetonitrile)Pd complex (R)-1
(1.1 g, 2.3 mmol) in dichloromethane (40 mL) was treated with (E)-
1-methyl-3-(pyridin-2-yl)-2-propenoate (0.411 g, 2.53 mmol) and
Ph2AsH (0.529 g, 2.3 mmol) at room temperature for 14 d. Re-
moval 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 crystallized from dichloromethane/diethyl ether to
give the complex (RC,SC)-7 as pale yellow crystals; m.p. 204–205 °C
(decomp.), [α]D = –77 (c = 0.6, CH2Cl2); 0.92 g (51 % yield).
C35H36AsClN2O6Pd (797.5): calcd. C 52.7, H 4.6, N 3.5; found C
52.3, H 4.5, N 3.1. 1H NMR (CD2Cl2): δ = 2.23 (d, 3JH,H = 6.4 Hz,
3 H, CHMe), 2.60 (s, 3 H, NMe), 3.00 (s, 3 H, NMe), 3.09 (s, 3 H,
Crystal Structure Determination of (R)-4 and (RC,SC)-7: X-ray crys-
tallographic data for the two complexes (R)-4 and (RC,SC)-7 are
given in Table 3. Diffraction data were collected on a Bruker
X8Apex diffractometer with Mo-Kα radiation (graphite monochro-
mator). SADABS absorption corrections were applied. All non-
hydrogen atoms were refined anisotropically. Hydrogen atoms were
introduced at fixed distances from carbon atoms and were assigned
to fixed thermal parameters. The absolute configurations of all chi-
ral complexes were determined unambiguously using the Flack pa-
rameter.[22]
Table 3. Crystallographic data for complexes (R)-4 and (RC,SC)-7.
3
2
COOMe), 3.49 (dd, JH,H = 13.0, JH,H = 2.3 Hz, 1 H, Ha), 3.82
(dd, 2JH,H = 14.3, 3JH,H = 2.3 Hz, 1 H, Hb), 4.13 (m, 1 H, Hc), 4.56
(R)-4
(RC,SC)-7
3
(qn, JH,H = 6.3 Hz, 1 H, CHMe), 6.63–8.08 (m, 19 H, aromatics),
Formula
fw
Space group
Crystal system
a [Å]
b [Å]
c [Å]
C26H22AsCl2NOPd C36H38AsCl3N2O6Pd
3
8.80 (d, JH,H = 5.3 Hz, 1 H, Hd) ppm.
616.67
P212121
orthorhombic
8.9848(4)
10.5337(5)
25.0414(12)
90
882.35
P21
monoclinic
10.0428(6)
17.9964(11)
10.3669(6)
90
α [°]
β [°]
90
90
94.719(3)
90
1867.30(19)
2
γ [°]
V [Å3]
2370.00(19)
4
Z
T [K]
173(2)
1.728
0.71073 (Mo)
2.414
1224
296(2)
1.569
0.71073 (Mo)
1.637
892
ρcalcd. [gcm–3]
λ [Å]
Dichloro [(S)-Methyl-2-(diphenylarsanyl)-3-(pyridin-2-yl)propano-
ate-(N1,As2)]palladium(II) [(S)-8]: The naphthylamine auxiliary in
(RC,SC)-7 was removed chemoselectively by adding concentrated
hydrochloric acid (15 mL) to a solution of the complex (RC,SC)-7
(0.3705 g, 0.46 mmol) in dichloromethane (20 mL). The reaction
mixture was stirred vigorously for 1 h at room temperature. The
reaction mixture was then washed with water (4ϫ10 mL) and dried
(MgSO4). Subsequently fractional crystallization from dichloro-
methane/diethyl ether gave complex (S)-8 as yellow prisms; m.p.
233–234 °C (decomp.), [α]D = –113 (c = 0.6, CH2Cl2); 0.2 g (91%
yield). C21H20AsCl2NO2Pd (570.6): calcd. C 44.2, H 3.5, N 2.5;
µ [mm–1]
F(000)
Flack parameter
R1 (obsd. data)[a]
wR2 (obsd. data)[b]
0.020(7)
0.0245
0.0556
0.009(10)
0.0414
0.0966
[a] R1 = ∑||Fo| – |Fc||/∑|Fo|. [b] wR2 = √{Σ[w(Fo – Fc2)2]/Σ[w(Fo ) ]},
2
2 2
w–1 = σ2(Fo2) + (aP)2 + bP.
CCDC-732832 [for (R)-4] and -732833 [for (RC,SC)-7] contain the
supplementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.cdcc.cam.ac.uk/data_request/cif.
1
found C 44.3, H 3.9, N 2.1. H NMR (CD2Cl2): δ = 3.18 (s, 3 H,
2
3
COOCH3), 3.35 (dd, JH,H = 12.3, JH,H = 2 Hz, 1 H, Ha), 3.78
2
3
3
(dd, JH,H = 14.5, JH,H = 2 Hz, 1 H, Hb), 4.04 (dd, JH,H = 14.5,
3JH,H = 12.3 Hz, 1 H, Hc), 7.34–8.14 (m, 14 H, aromatics), 9.34 (d,
3JH,H = 5.3 Hz, 1 H, Hd) ppm.
Acknowledgments
Methyl (S)-2-(Diphenylarsanyl)-3-(pyridin-2-yl)propanoate [(S)-9]: We are grateful to Nanyang Technological University for support-
A solution of (S)-8 (0.057 g, 0.1 mmol) in dichloromethane (15 mL)
ing this research and for the research scholarships to F. L. L.
Eur. J. Inorg. Chem. 2009, 4134–4140
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org 4139

F. Liu, S. A. Pullarkat, Y. Li, S. Chen, P.-H. Leung
FULL PAPER
[12] W. C. Yeo, S. T. Tee, G. K. Tan, L. L. Koh, P. H. Leung, Inorg.
Chem. 2004, 43, 8102–8109.
[13] F. Liu, S. A. Pullarkat, Y. Li, S. Chen, M. Yuan, Z. Lee, P. H.
Leung, Organometallics, in press.
[14] a) E. J. Corey, J. C. Bailar, J. Am. Chem. Soc. 1959, 81, 2620–
2629; b) M. D. Fryzuk, B. J. Bosnich, J. Am. Chem. Soc. 1977,
99, 6262–6267; c) P. A. MacNeil, N. K. Roberts, B. Bosnich, J.
Am. Chem. Soc. 1981, 103, 2273–2280.
[15] L. Pauling, The Nature of the Chemical Bond; Cornell Univer-
sity Press, Ithaca, NY, 1967.
[16] W. C. Yeo, L. Tang, B. Yan, S. Y. Tee, L. L. Koh, K. Geok,
P. H. Leung, Organometallics 2005, 24, 5581–5585.
[17] a) E. Costa, P. G. Pringle, M. B. Smith, K. Worboys, J. Chem.
Soc., Dalton Trans. 1997, 4277–4282 and references cited
therein; b) D. K. Wicht, I. V. Kourkine, I. Kovacik, D. S.
Glueck, T. E. Concolino, G. P. A. Yap, C. D. Incarvito, A. L.
Rheingold, Organometallics 1999, 18, 5381–5394; c) M. O. Shu-
lyupin, M. A. Kazankova, I. P. Beletskaya, Org. Lett. 2002, 4,
761–763 and references cited therein; d) M. R. Douglass, C. L.
Stern, T. J. Marks, J. Am. Chem. Soc. 2001, 123, 10221–10238;
e) W. Malisch, B. Klüpfel, D. Schumacher, M. Nieger, J. Or-
ganomet. Chem. 2002, 661, 95–110; f) A. D. Sadow, A. Togni,
J. Am. Chem. Soc. 2005, 127, 17012–17024; g) A. Kondoh, H.
Yorimitsu, K. Oshima, J. Am. Chem. Soc. 2007, 129, 4099–
4104; h) M. L. Bungabong, K. W. Tan, Y. Li, S. V. Selvaratnam,
K. G. Dongol, P. H. Leung, Inorg. Chem. 2007, 46, 4733–4736.
[18] a) S. Y. M. Chooi, M. K. Tan, P. H. Leung, K. F. Mok, Inorg.
Chem. 1994, 33, 3096–3103; b) M. Gomez, J. Granell, M. Mar-
tinez, Organometallics 1997, 16, 2539–2546; c) C. López, R.
Bosque, D. Sainz, M. Font-Bardía, Organometallics 1997, 16,
3261–3266; d) M. Gomez, J. Granell, M. Martinez, J. Chem.
Soc., Dalton Trans. 1998, 37–44.
[1]
a) V. K. Farina, B. Krishnan, J. Am. Chem. Soc. 1991, 113,
9585–9595; b) K. C. Nicolaou, P. G. Bulger, D. Sarlah, Angew.
Chem. Int. Ed. 2005, 44, 4442–4489; c) K. C. Y. Lau, P. Chiu,
Tetrahedron Lett. 2007, 48, 1813–1816.
R. A. Baber, S. Collard, M. Hooper, A. G. Orpen, P. G. Pringle,
M. J. Wilkinson, R. L. Wingad, Dalton Trans. 2005, 1491–
1498.
[2]
[3]
[4]
L. A. van der Veen, P. K. Keeven, P. C. Kamer, P. W. N. M.
van Leeuwen, Chem. Commun. 2000, 333–334.
a) C. R. Johnson, M. P. Braun, J. Am. Chem. Soc. 1993, 115,
11014–11015; b) R. B. Bedford, C. S. J. Cazin, S. J. Coles, T.
Gelbrich, M. B. Hursthouse, V. J. M. Scordia, Dalton Trans.
2003, 3350–3356.
S. Ceccarelli, U. Piarulli, C. Gennari, J. Org. Chem. 2000, 65,
6254–6256.
[5]
[6] J. A. Casares, P. Espinet, G. Salas, Organometallics 2008, 27,
3761–3769.
[7] P. Cao, C.-Y. Li, Y.-B. Kang, Z. Xie, X.-L. Sun, Y. Tang, J.
Org. Chem. 2007, 72, 6628–6630.
[8] a) A. D. Calhoun, W. J. Kobos, T. A. Nile, C. A. Smith, J. Or-
ganomet. Chem. 1979, 170, 175–179; b) B. A. Murrer, J. M.
Brown, P. A. Chaloner, P. N. Nicholson, D. Parker, Synthesis
1979, 350–352; c) A. Kojima, C. D. J. Boden, M. Shibasaki,
Tetrahedron Lett. 1997, 38, 3459–3460; d) Y. Cho, M. Shiba-
saki, Tetrahedron Lett. 1998, 39, 1773–1776; e) D.-M. Tan,
K. S. Chan, Tetrahedron Lett. 2005, 46, 503–505; f) C. Y. Wang,
D.-M. Tan, K. S. Chan, Y.-H. Liu, S.-M. Peng, S.-T. Liu, J.
Organomet. Chem. 2005, 690, 4920–4925; g) N. C. Payne, D. W.
Stephan, Inorg. Chem. 1982, 21, 182–188.
[9] a) G. R. Newkome, Chem. Rev. 1993, 93, 2067–2089; b) Z. Z.
Zhang, H. Cheng, Coord. Chem. Rev. 1996, 147, 1–37; c) P.
Espinet, K. Soulantica, Coord. Chem. Rev. 1999, 499, 499–556;
d) G. Chelucci, G. Orru, G. A. Pinna, Tetrahedron 2003, 59,
9471–9515; e) P. J. Guiry, C. P. Saunders, Adv. Synth. Catal.
2004, 346, 497–537; f) X. Cui, K. Burgess, Chem. Rev. 2005,
105, 3272–3296.
[19] S. Y. M. Chooi, P. H. Leung, C. C. Lim, K. F. Mok, G. H.
Quek, K. Y. Sim, M. K. Tan, Tetrahedron: Asymmetry 1992, 3,
529–532.
[20] T. Bakó, P. Bakó, G. Keglevich, N. Báthori, M. Czugler, J.
Tatai, T. Novák, G. Parlagh, L. Töke, Tetrahedron: Asymmetry
2003, 14, 1917–1923.
[21] S. D. Bull, S. G. Davies, D. J. Fox, M. Gianotti, P. M. Kelly, C.
Pierres, E. D. Savory, A. D. Smith, J. Chem. Soc. Perkin Trans.
1 2002, 1858–1868.
[10] F. Y. Kwong, C. W. Lai, K. S. Chan, J. Am. Chem. Soc. 2001,
123, 8864–8865.
[11] F. Y. Kwong, C. W. Lai, D.-M. Tan, F. L. Lam, A. S. C. Chan,
K. S. Chan, Organometallics 2005, 24, 4170–4178.
[22] H. D. Flack, Acta Crystallogr., Sect. A 1983, 39, 876–881.
Received: May 21, 2009
Published Online: August 10, 2009
4140
www.eurjic.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 4134–4140