Preparation, coordination and catalytic use of planar-chiral monocarboxylated dppf analogues

Article abstract of DOI:10.1039/b901262a

A novel polar dppf derivative possessing only planar chirality, 1′,2-bis(diphenylphosphino)-ferrocene-1-carboxylic acid (Hdpc), has been synthesised in racemic form and resolved into enantiomers via esters with d-glucose diacetonide ((R_p)- and (S_p)-3). (R _p)-Hdpc was further converted to a series of N-substituted amides that were studied as ligands for Pd-catalysed enantioselective allylic alkylation of racemic (E)-1,3-diphenylprop-2-en-1-yl acetate or ethyl carbonate with malonate esters, showing high activity and good enantioselectivity (er up to 10: 90). The catalytic results were correlated with the structural data (X-ray diffraction and solution NMR) for (η³-allyl)palladium(ii) complex (R_p)-[Pd(η³-1,3-Ph₂C ₃H₃){Fe(η⁵-C₅H ₃-1-(C(O)NHCH₂Ph)-2-(PPh₂-κP)) (η⁵-C₅H₄PPh₂-κP)}]ClO ₄ (16) as a model of the plausible reaction intermediate. A further study into the coordination properties of Hdpc led to isolation of chelate complex [PdCl₂(Hdpc-κ²P,P′)] (12). The crystal structures of rac-Hdpc, methyl ester of (R_p)-Hdpc, glycoside (R _p)-3, and 12·Me₂CO suggested a close structural relationship between dppf and Hdpc. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009.

Full text of DOI:10.1039/b901262a

View Article Online / Journal Homepage / Table of Contents for this issue
PAPER
www.rsc.org/njc | New Journal of Chemistry
Preparation, coordination and catalytic use of planar-chiral
monocarboxylated dppf analoguesw
ˇ
ˇ ˇ ˇ
Martin Lamac, Ivana Cısarova and Petr Stepnicka*
´
´
ˇ
Received (in Montpellier, France) 20th January 2009, Accepted 25th February 2009
First published as an Advance Article on the web 9th April 2009
DOI: 10.1039/b901262a
A novel polar dppf derivative possessing only planar chirality, 10,2-bis(diphenylphosphino)-
ferrocene-1-carboxylic acid (Hdpc), has been synthesised in racemic form and resolved into
enantiomers via esters with D-glucose diacetonide ((Rp)- and (Sp)-3). (Rp)-Hdpc was further
converted to a series of N-substituted amides that were studied as ligands for Pd-catalysed
enantioselective allylic alkylation of racemic (E)-1,3-diphenylprop-2-en-1-yl acetate or ethyl
carbonate with malonate esters, showing high activity and good enantioselectivity
(er up to 10 : 90). The catalytic results were correlated with the structural data
(X-ray diffraction and solution NMR) for (Z3-allyl)palladium(II) complex
(Rp)-[Pd(Z3-1,3-Ph2C3H3){Fe(Z5-C5H3-1-(C(O)NHCH2Ph)-2-(PPh2-kP))(Z5-C5H4PPh2-kP)}]ClO4
(16) as a model of the plausible reaction intermediate. A further study into the coordination
properties of Hdpc led to isolation of chelate complex [PdCl2(Hdpc-k2P,P0)] (12). The crystal
structures of rac-Hdpc, methyl ester of (Rp)-Hdpc, glycoside (Rp)-3, and 12ꢀMe2CO suggested
a close structural relationship between dppf and Hdpc.
Introduction
Since it was first reported in 1965,1 1,10-bis(diphenylphosphino)-
ferrocene (dppf) found manifold uses in coordination chemistry
and homogeneous catalysis.2 The practical success of dppf
also stimulated further research into its simple analogues
(I, Scheme 1)3 and the related chiral donors (II). The chiral
derivatives received particular attention, being versatile and
efficient ligands for asymmetric metal-mediated reactions.4
Despite the enormous amount of research work directed into
the area of chiral dppf derivatives, their chemistry is still
markedly dominated by BPPFA-type compounds that are
readily available in optically pure form from Ugi’s amine,
FcCH(Me)NMe2 (Fc = ferrocenyl) via directed ortho-lithiation5
Scheme 1
and manipulation of the NMe2 group.4 In addition to the
archetypal BPPFA (II, Y = CH(Me)NMe2),6,7 a number of
related compounds have been reported in which the NMe2
group was replaced with another donor moiety or the whole
aliphatic chain was transformed.7,8 Other II-type compounds
still remain uncommon: a ferrocene triphosphine (II, Y = PPh2)9
and ferrocene diphosphine-oxazolines (II, Y = C-chiral
4,5-dihydrooxazolin-2-yl)4b,10 may serve as typical examples.
The lack of monofunctionalised dissymmetric dppf
analogues together with our ongoing interest in the chemistry
of ferrocene phosphinocarboxylic ligands11,12 led us to design
a novel monocarboxylic derivative of dppf, 10,2-bis(diphenyl-
phosphino)ferrocene-1-carboxylic acid (Hdpc in Scheme 1).
With its particular disposition of the donor moieties, Hdpc is
inherently chiral with the 1,2-disubstituted ferrocene moiety
serving as the sole chirality source (N.B. The majority of chiral
ferrocene ligands II possess simultaneously planar and central
chirality). Besides, Hdpc fills a gap left between 10-(diphenyl-
phosphino)ferrocene-1-carboxylic acid (Hdpf),11,13 its planar
chiral isomer, 2-(diphenylphosphino)ferrocene-1-carboxylic
acid (III),14,15 and the C2-symmetric 2,20-bis(diphenylphosphino)-
ferrocene-1,10-dicarboxylic acid (IV, Scheme 1),16 which have
all been studied as donors in asymmetric metal-catalysed
organic reactions.
Department of Inorganic Chemistry, Faculty of Science,
Charles University in Prague, Hlavova 2030, Prague 2, 12840,
Czech Republic. E-mail: stepnic@natur.cuni.cz;
Fax: +420 221 951 253
w Electronic supplementary information (ESI) available: An alter-
native view of the molecular structure of 12a (Fig. S1), representative
kinetic profile for the alkylation reaction (Fig. S2), geometric data for
the glucofuranosyl moiety in (Rp)-3 (Table S1), and numerical data for
the non-linear catalytic study (Table S2). CCDC numbers
700753–700757. For ESI and crystallographic data in CIF or other
electronic format see DOI: 10.1039/b901262a
With this contribution, we describe the synthesis of racemic
Hdpc, its resolution into enantiomers and the preparation
of a series of enantiopure amides from (Rp)-Hdpc. We
also report the preparation and structural characterisation
of palladium(II) complexes featuring rac-Hdpc and
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009 New J. Chem., 2009, 33, 1549–1562 | 1549

View Article Online
(Rp)-10,2-bis(diphenylphosphino)-1-(N-benzylcarbamoyl)ferrocene
as P,P0-chelate ligands and the use of Hdpc-based donors in
palladium-catalysed asymmetric allylic alkylation.
4 by column chromatography and subsequently crystallised
from diethyl ether–hexane to afford optically pure (Rp)-3 in
35% isolated yield (i.e., 70% of the theoretical amount based
on rac-Hdpc). Chromatographic separation of the combined
crystallisation residua afforded optically pure (Sp)-3.19
Results and discussion
The isomeric glycosides and the urea derivative were
characterised by elemental analysis and by spectral methods
(NMR, IR, and MS). Besides, the configuration of (Rp)-3 was
unequivocally established by X-ray diffraction analysis. In the
NMR spectra, the ferrocene signals of (Rp)-3, (Sp)-3 and 4 are
observed fully non-equivalent and appear at positions similar
to their parent acid. The transformations of the carboxyl
group are nicely reflected by changes in the region of the
CQO signals. Upon esterification, this resonance shifts to
higher fields (cf. dC 170.13/169.39 for (Rp)/(Sp)-3, and 174.80
for Hdpc) while, in the case of urea 4, it is replaced by two
signals at characteristic positions (dC 154.36 and 170.71).18,20
Consistently, the glycosides exhibit their nCQO IR bands
shifted to higher energies as compared with Hdpc while 4
Preparation and characterisation of Hdpc and its amide
derivatives
Racemic Hdpc was synthesised (Scheme 2) by sequential
lithiation and phosphinylation of 10,2-dibromoferrocene-1-
carboxylic acid (2), which was obtained from 1,10-dibromo-
ferrocene (1) as recently reported by Butler and co-workers.9c
Crude Hdpc typically contains minor amounts of Hdpf
and III, both resulting from accidental protonolysis of the
lithiated intermediate. These acids are chemically similar but,
fortunately, could be removed by careful column chromato-
graphy. Alternatively, Hdpc was prepared by directed
ortho-lithiation of Hdpf with sec-butyllithium and subsequent
phosphinylation (Scheme 2). This route, however, proved
rather impractical due to relatively lower isolated yields.
Hdpc was characterised by conventional spectral methods
(NMR, IR and MS) and its structure was corroborated by
X-ray crystallography. In NMR spectra, Hdpc displays seven
1H and ten 13C resonances attributable to chemically different
and/or diastereotopic ferrocene CH and C groups. The
presence of non-equivalent PPh2 moieties is manifested by
two sets of signals due to diastereotopic C and CH phenyl
protons in the 13C{1H} NMR and by two singlets in the
31P{1H} NMR spectrum (CDCl3: dP ꢂ18.2, ꢂ18.1; (CD3)2SO:
dP ꢂ19.0, ꢂ17.7). The IR spectrum of Hdpc is dominated by a
strong nCQO band at 1675 cmꢂ1 (cf. 1666 cmꢂ1 for Hdpf13).
The resolution of rac-Hdpc was achieved via esters with
D-glucose diacetonide14d,17 (Scheme 2). Racemic Hdpc was
first reacted with D-glucose diacetonide in the presence of
N,N0-dicyclohexylcarbodiimide and 4-(dimethylamino)pyridine
to give a mixture of diastereomeric glucosides 3 along with the
urea derivative 4.18 The glycoside fraction was separated from
shows the diagnostic urea bands at 1699 and 1517 cmꢂ1 18,20
.
The NMR parameters of the carbohydrate part in (Rp)-3
and (Sp)-3 correspond with those of free D-glucose
diacetonide.21 A notable exception is the splitting of the
carbohydrate CH-500 proton with phosphorus (see Scheme 8),
1
which was confirmed by 31P-decoupled H NMR spectra. In
view of the structural data revealing a favourable orientation
and distance22 of the interacting molecular parts (PꢀꢀꢀH5 3.08 A,
Pꢀ ꢀ ꢀH5–C5 1581), this splitting can be accounted for a through-
space interaction rather than for a long-range scalar coupling.
In the next step, glucofuranosides (Rp)- and (Sp)-3 were
hydrolysed to give the respective Hdpc enantiomers. The
hydrolysis was carried out with 1 M KOH in a THF–methanol–
water mixture at 50 1C overnight. Subsequent work up
afforded optically pure (Rp)- and (Sp)-Hdpc in good isolated
yields (76 and 69%, respectively). When the hydrolysis was
carried out at room temperature, it did not reach completion.
In addition to Hdpc and unreacted glycoside, the reaction
mixture contained a minor amount of Hdpc-methyl ester
Scheme 2 Preparation and resolution of Hdpc (DCC = N,N0-dicyclohexylcarbodiimide, DMAP = 4-(dimethylamino)pyridine).
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009
1550 | New J. Chem., 2009, 33, 1549–1562

View Article Online
Fig. 1 Proton NMR spectra of (Rp)-7 as recorded in C6D6 (top) and
in CDCl3 (bottom) at 25 1C. In both cases, three ferrocene CH
resonances fall outside the range indicated.
molecular structures are shown in Fig. 2–4. Selected geometric
data for the acid are given in the figure caption while those for
(Rp)-5 and (Rp)-3 are presented in Table 1.
Scheme 3 Preparation of amides 6–10 (HOBt = 1-hydroxybenzotriazole,
EDC = N-[3-(dimethylamino)propyl]-N0-ethyl-carbodiimide).
The overall molecular structure of rac-Hdpc (Fig. 2a) and,
consequently, its crystal packing seems to be dictated largely
by the bulky peripheral phosphino groups and by a tendency
to attain a higher symmetry (inversion centre). As a result, the
‘embedded’ carboxyferrocenyl moiety is disordered over two
((Rp)-5), which was isolated and characterised spectro-
scopically and by X-ray crystallography.
Aiming at utilisation in catalysis, (Rp)-Hdpc was further
converted to a series of secondary amides. The series was
designed so that both steric properties and chirality of the
amide substituents varied (Scheme 3). Amide coupling in the
presence of 1-hydroxybenzotriazole and N-[3-(dimethylamino)-
propyl]-N0-ethylcarbodiimide23,24 proceeded smoothly to give
pure amides in good yields. A notable exception was the
amidation with benzhydryl amine in the case of which
the amide formation was partly hindered by the steric bulk
of the amine and some intermediate benzotriazolyl ester
(Rp)-11 was also isolated.25
Compounds 6–10 exhibit characteristic amide bands
1
(nNH, amide I/II) in the IR spectra. Their H NMR spectra
fully corroborate the formulation by combining the signals of
the phosphinoferrocene moiety with those due to the nitrogen
substituents. It is worth noting that despite the non-degenerate
nature of the NMR signals, the spectra may turn deceptively
simple. For instance, the 1H NMR spectrum of (Rp)-7
recorded in CDCl3 showed the PhCH2 protons as a doublet
resulting from interaction with the NH proton (Fig. 1). When
the spectrum was recorded in C6D6, the same signal was
observed as a pair of double doublets as expected for
diastereotopic CH2 protons interacting with an NH group
3
(2JHH = 14.9, JHH = 5.9 Hz). The ferrocene signals also
became better resolved in the latter solvent. 31P NMR data of
6–10 do not differ much from those of Hdpc. However, the
individual signals are better separated (DdP = 2.0–2.8 ppm,
cf. DdP = 0.1 ppm for Hdpc in CDCl3).
Fig. 2 (a) View of the molecular structure of rac-Hdpc, showing the
atom labelling scheme and displacement ellipsoids at the 30%
probability level [the (Rp) component is shown]. (b) Superposition of
both orientations encountered in the crystals of rac-Hdpc. Selected
distances and angles: Fe1–Cg1 1.66(3), Fe1–Cg2 1.64(3) A, +Cp1,Cp2
1.0(3)1; C11–O1 1.233(4), C11–O2 1.309(4), C1–C11 1.450(5) A;
O1–C11–O2 124.1(3)1; C2–P1 1.964(7)/C6–P10 1.683(9), P1–C12
1.837(2), P1–C18 1.833(2) A. Primed atoms are generated by the
crystallographic (1 ꢂ x, ꢂy, ꢂz) symmetry operation. For definition
of the ring planes, see Table 1.
The crystal structures of rac-Hdpc, ester (Rp)-5 and glycoside
(Rp)-3
Crystal structures of rac-Hdpc, (Rp)-5 and (Rp)-3 were
determined by single-crystal X-ray diffraction. Views of the
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009 New J. Chem., 2009, 33, 1549–1562 | 1551

View Article Online
inversion-related positions (enantiomers; Fig. 2b), which
underscores structural similarity between Hdpc and dppf.26,27
Geometric data for rac-Hdpc do not depart significantly
from those reported for dppf,27 Hdpf,13 2-(diphenylphosphinoyl)-
ferrocene-1-carboxylic acid14c and its corresponding alcohol,28
particularly when the relatively lower precision of the geo-
metry determination for the disordered ferrocene scaffold is
considered. The adjacent phosphine and carboxyl groups
do not impart any notable deformation to their bonding
cyclopentadienyl ring Cp1 as evidenced by the torsion angle
C11–C1–C2–P1 = 3.1(9)1 but the carboxyl plane is rotated
from the Cp1 plane by 10.1(5)1.
Similarly to Hdpf,13 individual molecules of rac-Hdpc
associate into dimers via centrosymmetric double hydrogen
bridges between their carboxyl groups (O1ꢀ ꢀ ꢀO2 2.630(3) A;
angle at H = 1681). Because of the disorder, the hydrogen-
bonded pairs can be described equally well as being composed
either of the molecule and its inverted image or, alternatively,
of the molecule and the other contributing component
translated in the crystallographic a direction.
Fig. 4 View of the molecular structure of (Rp)-3 showing displace-
ment ellipsoids at the 30% probability level. An alternative view of the
glucofuranosyl part and selected geometric data are available as ESIw.
Structural data for ester (Rp)-5 also compare well with those
of dppf27 and Hdpf methyl ester.13 The cyclopentadienyl (Cp)
rings are mutually tilted only by 0.6(1)1 and the Fe–ring
centroid distances are similar. The ferrocene moiety does not
exert any torsional deformation at the C1–C2 bond, yet the
substituents bind somewhat asymmetrically.29 The diphenyl-
phosphino groups assume a staggered antiperiplanar confor-
mation with t = 1781. Even though the crystals of (Rp)-5 are
chiral (space group P21), such molecular conformation results
in an apparent pseudoinversion symmetry, which is violated
only by the carboxyl substituent (compare the unit cell
parameters of rac-Hdpc and (Rp)-5).
Table 1 Selected distances and angles for (Rp)-5 and (Rp)-3 (in A and 1)a
Compound
(Rp)-5d
(Rp)-3e
Fe–Cg1
Fe–Cg2
+Cp1, Cp2
C11–C1–C2–P1
tb
C1–C11
C11–O1
C11–O2
O1–C11–O2
jc
1.6493(9)
1.6529(9)
0.6(1)
4.9(3)
178
1.474(3)
1.200(3)
1.338(3)
123.4(2)
8.0(2)
1.645(1)
1.656(1)
2.5(2)
3.2(4)
154
1.465(4)
1.209(3)
1.356(3)
123.0(2)
11.0(3)
1.833(3)
1.813(2)
The structure of glycoside (Rp)-3 (Fig. 4) is not unexpected
in view of the structural data of rac-Hdpc and (Rp)-5 (Table 1).
When compared with the latter compound, (Rp)-3 shows a
somewhat higher tilt of the ferrocene cyclopentadienyls and
rotation of the carboxyl plane. The most notable difference,
P1–C2
P2–C6
1.825(2)
1.826(2)
a
The ring planes are defined as follows: Cp1 = C(1–5), Cp2 =
b
C(6–10); Cg1 and Cg2 are the respective ring centroids. Torsion
c
angle C2–Cg1–Cg2–C6. Dihedral angle of the {C11,O1,O2} and Cp1
d
least-squares planes. Other data: O2–C36 1.439(3) A; C11–O2–C36
e
117.4(2)1. For data describing the glucofuranosyl moiety, see ESIw,
Table S1.
however, is seen in the conformation of the ferrocene moiety,
which is near to anti-eclipsed. The geometry of the 1,2:5,6-di-
O-isopropylidene-a-D-3-gluco-furanosyl moiety (see Table S1,
ESIw) compares favourably to that reported for the related
derivatives of organic acids.30
Synthesis and characterisation of complex 12
Reaction of rac-Hdpc with [PdCl2(cod)] (cod = Z2:Z2-
cycloocta-1,5-diene) in chloroform afforded chelate complex
rac-[PdCl2(Hdpc-k2P,P0)] (12) as an orange, poorly soluble
microcrystalline solid (Scheme 4). X-Ray quality crystals of
the solvate rac-[PdCl2(Hdpc-k2P,P0)]ꢀMe2CO (12a) were
grown by diffusion of [PdCl2(cod)] in acetone into a solution
of the acid in CHCl3.
NMR spectra of 12 are in accordance with the formulation,
showing one set of ferrocene signals. The spectra also suggest
P,P-chelate coordination of the ligand via a shift of the
Fig. 3 View of the molecular structure of ester (Rp)-5. Displacement
ellipsoids enclose the 30% probability level.
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009
1552 | New J. Chem., 2009, 33, 1549–1562

View Article Online
Table 2 Selected distances and angles for 12a (in A and 1)a,b
Distances
Angles
Pd–Cl1
Pd–Cl2
Pd–P1
2.3379(6)
2.3390(6)
2.2912(6)
2.2822(6)
1.629(1)
1.643(1)
1.803(2)
1.809(2)
1.209(3)
1.338(3)
Cl1–Pd–Cl2
Cl1–Pd–P1
Cl2–Pd–P2
P1–Pd–P2
PdL4 vs. Cp1c
+Cp1,Cp2
C11–C1–C2–P1
td
87.27(2)
88.76(2)
83.47(2)
100.35(2)
67.1(1)
2.3(2)
1.4(3)
26
124.4(2)
17.4(3)
Pd–P2
Fe–Cg1
Fe–Cg2
P1–C2
P2–C6
C11–O1
C11–O2
Scheme 4 Preparation of palladium(II) complex 12.
O1–C11–O2
jd
a
Definition of the ring planes: Cp1 = C(1–5), Cp2 = C(6–10); Cg1
b
and Cg2 denote the respective ring centroids. Data for the solvent
molecule: C90–O90 1.208(4), C90–C91 1.504(4), C90–C92 1.466(6) A;
c
C91–C90–C92 119.6(3)1. The dihedral angle of the {Pd,Cl1,
d
Cl2,P1,P2} and Cp1 planes. Parameters t and j are defined as for
free ligands (see Table 1).
Catalytic tests
Glycosides (Rp)- and (Sp)-3 and the donors relating to
(Rp)-Hdpc (the acid and all amides shown in Scheme 2) have
been studied as ligands for palladium-catalysed asymmetric
allylic alkylation (Scheme 5)36 of (E)-1,3-diphenylprop-2-en-1-
yl acetate (13a) or its corresponding ethyl carbonate 13b with
C-anions generated from dialkyl malonates and N,O-bis-
(trimethylsilyl)acetamide in the presence of alkali metal
acetates.37 The reactions were usually carried out in dichloro-
methane at room temperature using
3
mol% of
Fig. 5 View of the molecular structure of 12a showing the atom
labelling scheme and displacement ellipsoids at the 30% probability
level. Hydrogen bond between the carboxyl OH group and the solvate is
indicated with a dotted line (O2ꢀꢀꢀO90 = 2.621(3) A, angle at H2 = 1561).
Pd-catalyst formed in situ from the respective ligand and
[{Pd(m-Cl)(Z3-C3H5)}2] (Pd : ligand = 1 : 1).
The experiments with (S,Rp)-8 suggested that the alkylation
reaction with dimethyl malonate is typically completed within
1 h (for a representative kinetic profile, see Fig. S2, ESIw) and
its stereochemical outcome (ee)38 is perfectly reproducible.
Nevertheless, the reaction times were uniformly set to 20 h
in order to minimise a bias due to varying induction
periods and different reactivity of the C-nucleophiles tested
(dimethyl vs. di-tert-butyl malonate).
31P NMR signals to lower fields (dP 33.5 and 43.7) and, above
all, their mutual coupling (2JPP = 35 Hz). The nCQO band is
observed at 1703 cmꢂ1, i.e. shifted by about 30 cmꢂ1 to higher
energies vs. solid Hdpc.
The crystal structure of solvate 12a was established by X-ray
diffraction analysis (Fig. 5, Table 2). Coordination geometry
around the palladium is generally similar31 to that reported for
[PdCl2(dppf-k2P,P0)]ꢀS, where S = CH2Cl2,32 and CHCl3.33
The coordination environment around palladium is cis square-
planar, with the palladium and its four ligating atoms being
coplanar within 0.055 A.34 The Pd–donor distances are quite
similar but the interligand angles differ from the ideal 901. The
P1–Pd–P2 (or the ligand bite angle) is the most opened.
Nonetheless, this opening seems to be well compensated by
in-plane closure of the remaining angles as the sum of the
interligand angles (359.851) rules out any pronounced tetra-
hedral distortion. The geometry of the ferrocene moiety in 12a
remains largely unchanged upon coordination35 but the ligand
molecule undergoes a pronounced conformational change. In
order to allow for chelate formation, the phosphorus groups
are rotated closer to each other to a position roughly halfway
between syn-eclipsed and syn-staggered (t = 261). The
coordination plane and the ferrocene unit are tilted at
the dihedral angle of the Cp1 and PdL4 planes of 67.1(1)1
(see Fig. S1, ESIw).
Another series of reactions performed with the mixtures of
isomeric ligands (Rp)-3 and (Sp)-3 excluded major non-linear
effects39 operating in the catalytic system (Fig. 6). The eeproduct
was always proportional to deligand within the experimental
error (ca. ꢃ1% ee), which points to a dominating role of
planar chirality. Indeed, this observation is in line with the
structural data (see below) indicating that Hdpc-based ligands
coordinate to palladium as P,P0-chelate donors. Thus,
although chiral, the glucofuranosyl groups (Rp)-3 and (Sp)-3
act as ‘innocent’, sterically demanding groups that only direct
Scheme 5
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009 New J. Chem., 2009, 33, 1549–1562 | 1553

View Article Online
Table 4 Optimisation of the reaction conditions with ligand (S,Rp)-8a
Entry
T/1C
Ligand
Substrate
Base
Ee (%) [config]
1
2
3
4
5
6
7
8
22
22
22
22
22
22
0
22
22
22
22
(S,Rp)-8
(S,Rp)-8
(S,Rp)-8
(S,Rp)-8
(S,Rp)-8
(S,Rp)-8
(S,Rp)-8
(S,Rp)-8
(S,Rp)-8
(R,Rp)-8
(Rp)-7
13a
13a
13a
13a
13a
13a
13a
13b
13a
13a
13a
LiOAc
NaOAc
KOAc
RbOAc
CsOAc
None
NaOAc
NaOAc
NaOAc
NaOAc
NaOAc
+52 [R]
+67 [R]
+66 [R]
+68 [R]
+68 [R]
+57 [R]
+67 [R]
+65 [R]
+80 [R]
+77 [R]
+63 [R]
9b
10b
11b
a
The alkylation of 13a and 13b was performed with a mixture of the
respective dialkyl malonate (3 equiv.), BSA (3 equiv.) in the presence
of catalytic amount of NaOAc (6 mol% with respect to the allylic
substrate; if appropriate) and 3 mol% of Pd-catalyst generated in situ
from [{Pd(m-Cl)(Z3-C3H5)}2] and the ligand (Pd : ligand = 1).The
Fig. 6 Variation of asymmetric induction (eeproduct) as a function of
de for the mixture of diastereomeric ligands (Rp)- and (Sp)-3 in allylic
alkylation of 13a with dimethyl malonate. Parameters of the linear fit:
eeproduct = 0.61(2) deligand + 1(2) (r2 = 0.996); for numerical data, see
ESIw (Table S2).
conversions were quantitative with the exception of entries
(conv. 93%) and 11 (conv. 88%). For detailed conditions, see
9
b
Experimental. The reaction was performed with di-tert-butyl
malonate as the nucleophile.
access of the nucleophile towards the Z3-allyl intermediate
(vide infra).
The results obtained with various ligands (Table 3) indicate
that the conversion of the carboxyl to a carboxamido group
has a beneficial effect on the ee. On the other hand, the
stereochemical course was rather insensitive to the substitution
at the amide nitrogen (even for the functionalised amide (Rp)-10).
The amides bearing the 1-phenylethyl substituents, (R,Rp)-8
and (S,Rp)-8, represented a typical example of matched and
mismatched chirality. Whereas the (R)-1-phenylethyl deriva-
tive showed the lowest ee among the amides, approaching that
achieved with (Rp)-Hdpc itself, its diastereoisomer (S,Rp)-8 gave
the alkylation product with the highest ee. Notably, when pre-
formed complex [Pd(Z3-1,3-Ph2C3H3){(Rp)-7-k2P,P0}]ClO4
((Rp)-16; vide infra) was employed as the ‘catalyst’, the ee
was considerably lower than with the corresponding catalyst
generated in situ (Table 3, entries 5 and 10).
changing the base additive, the nucleophile and the reaction
temperature (Table 4). Reactions performed without
any alkali metal acetate or in the presence of LiOAc gave
significantly lower ee’s than those carried out with all other
salts (Na–Cs). The variation among the heavier alkali metal
acetates was negligible. A lowering of the reaction temperature
to 0 1C or the use of 13b as a substrate did not improve the
reaction selectivity either. An increase in ee was achieved
with a more sterically demanding nucleophile (di-tert-butyl
malonate), though in different extent for the different ligands
(Table 4).
Preparation and crystal structure of the model complex
(Rp)-16—mechanistic implications
In attempts at improving the stereoselectivity, the catalytic
system based on (S,Rp)-8 as the best ligand was varied by
In order to gain a structural insight into the factors controlling
the stereochemistry of the alkylation reaction, Z3-1,3-diphenyl-
allyl complex (Rp)-16 was synthesised and structurally
characterised as a model for the plausible reaction inter-
mediate. The compound smoothly resulted by bridge-cleavage
of dimer 15 followed by halide abstraction with silver(I)
perchlorate (Scheme 6). Evaporation of the reaction mixture
afforded essentially pure product ( Z 90% according to NMR;
Fig. 7) in good yield.
Table
3 Survey of the chiral ligands in palladium-catalysed
asymmetric allylic alkylationa
Entry
Ligand
Ee (%) [config]
1
2
3
4
5
6
7
8
9
10
(Rp)-Hdpc
(Rp)-3
(Sp)-3
(Rp)-6
(Rp)-7
(R,Rp)-8
(S,Rp)-8
(Rp)-9
(Rp)-10
Complexb
+54 [R]
+65 [R]
ꢂ60 [S]
+60 [R]
+60 [R]
+55 [R]
+67 [R]
+58 [R]
+58 [R]
+49 [R]
The composition of the cation in (Rp)-16 was established
from high-resolution mass spectra whilst the presence of the
perchlorate counterion was confirmed by its n3 (1097 cmꢂ1
)
and n4 bands (624 cmꢂ1) in the IR spectrum. Although the
a
The alkylation of 13a was performed with dimethyl malonate–BSA
mixture (both 3 equiv. with respect to 13a) in the presence of catalytic
amount of NaOAc (6 mol% with respect to 13a) and 3 mol% of
Pd-catalyst generated in situ from [{Pd(m-Cl)(Z3-C3H5)}2] and the
ligand (Pd : ligand = 1). The results are an average of two independent
runs. The conversions determined by 1H NMR spectroscopy were
b
quantitative in all cases. For details, see Experimental. The reaction
was performed in the presence of 3 mol% of (Rp)-16.
Scheme 6
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009
1554 | New J. Chem., 2009, 33, 1549–1562

View Article Online
Fig. 7 31P{1H} NMR spectrum of crude (Rp)-16 (CDCl3, 25 1C). The
doublets integrate to the same value.
NMR spectra of (Rp)-16 could be analysed only partly due to
extensive signal overlaps, they provided valuable information
about the coordination of the ferrocene ligand. For instance,
31P{1H} NMR spectrum (Fig. 7) displayed a pair of doublets
2
with JPP = 61 Hz, indicating that (Rp)-7 coordinates as a
P,P0-chelate. The fact that the amide group is not involved in
coordination was inferred from a negligible coordination shift
of the 13C NMR signal of the CONH group (DdC = 0.5 ppm)
and nearly intact amide bands in the IR spectrum. The
resonances due to the Z3-1,3-diphenylallyl ligand were
observed in the expected region40 but with only a minor
differentiation between the allylic termini [DdH E 0.6,
DdC = 2.4; cf. the data for donor-dissymmetric complexes in
ref. 40]. Actually, this observation is hardly surprising in view
of the donor-symmetric nature of (Rp)-7 which in turn implies
that the stereochemical course of the reactions is controlled
predominantly by steric factors.
Crystals of (Rp)-16ꢀ2CH3CO2Et ((Rp)-16a) suitable for
X-ray diffraction analysis resulted upon crystallisation
of the complex from ethyl acetate. However, the solvent
molecules were disordered in structural voids and their
contribution was subtracted from the overall diffraction
pattern (see Experimental). A view of the cation in (Rp)-16a
is shown in Fig. 8 and selected geometric parameters are
presented in Table 5.
Fig. 8 (a) View of the cation in the structure of (Rp)-16a showing the
atom-labelling scheme (20% displacement ellipsoids). For clarity,
the hydrogen atoms are omitted and atomic labels of the allyl
ligand are shown in bold. (b, c) Space filling models of the cation as
viewed perpendicular to the allyl plane (b) and along the C43–C45
vector (c).
Table 5 Selected distances and angles for (Rp)-16a (in A and 1)a
The crystal structure reveals the diphenylallyl ligand in
(Rp)-16a to have a syn–syn conformation and to assume an
exo orientation vs. the carbamoyl group. The allyl plane
{C43,C44,C45} is rotated by 65.3(6)1 from the {Pd,P1,P2}
plane so that the central C44 atom is closest to the palladium.
The coordination geometry around the palladium atom is
quite symmetric in both Pd-donor distance and interligand
angles and generally corresponds with that reported
for [Pd(Z3-1,3-Ph2C3H3)(L-k2P,P0)]BF4ꢀC6H6, where L is
(S,S)-1,10-bis{phenyl(1-naphthyl)phosphino}ferrocene.41
Despite the symmetry of the coordination environment, the
1,3-diphenylallyl moiety is considerably twisted. This is a
likely consequence of steric constraints imposed by the bulky
PPh2 groups, forcing the phenyl rings at Z3-allyl group away
from the ferrocene ligand. This torsion is manifested by the
torsion angles C44–C43–C46–C(47/51) = 33.1(8)/ꢂ142.8(6)1
and C44–C45–C52–C(53/57) = ꢂ19.1(9)/157.0(6)1, departing
notably from 0/1801 for an ideal all-in-plane conformation.
The phenyl rings C(46–51) and C(52–57) are mutually rotated
by 38.0(3)1. Nonetheless, such deformation need not
Distances
Angles
Pd–P1
Pd–P2
2.344(1)
2.330(1)
2.256(5)
2.181(6)
2.226(6)
1.384(7)
1.395(8)
1.456(8)
1.480(8)
1.640(2)
1.640(3)
1.824(6)
1.804(5)
1.230(7)
1.328(8)
P1–Pd–P2
102.54(5)
96.2(1)
94.8(1)
128.6(2)
127.3(1)
66.2(2)
123.4(6)
123.6(6)
122.7(6)
65.3(6)
2.3(3)
P1–Pd–C43
P2–Pd–C45
P1–Pd–C44
P2–Pd–C44
C43–Pd–C45
C43–C44–C45
C46–C43–C44
C52–C45–C44
Allyl vs. {PdP2}b
+Cp1,Cp2
C11–C1–C2–P1
tc
Pd–C43
Pd–C44
Pd–C45
C43–C44
C44–C45
C43–C46
C45–C52
Fe–Cg1
Fe–Cg1
P1–C2
6.7(7)
30
121.9(4)
6.5(6)
P2–C6
C11–O1
C11–N1
O1–C11–N1
jd
a
Definition of the ring planes: Cp1 = C(1–5), Cp2 = C(6–10);
b
Cg1 and Cg2 denote the respective ring centroids. Dihedral angle
c
of the planes {C43,C44,C45} and {Pd,P1,P2}. Torsion angle
d
C2–Cg1–Cg2–C6. Dihedral angle of the {C11,O1,N1} and Cp1
least-squares planes.
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009 New J. Chem., 2009, 33, 1549–1562 | 1555

View Article Online
necessarily destabilise the structure. In the present case, it
seems to aid the generation of conformation-stabilising offset
pꢀ ꢀ ꢀp stacking interactions42 between phenyl rings of the allyl
ligand and the PPh2 moieties. The planes of the phenyl rings
C(46–51) and C(12–13) are tilted by 2.4(4)1 and the distance of
the ring centroids is 3.684(5) A, which is very similar to
centroid separation in a-graphite.43 The arrangement at the
other allyl terminus is less favourable but still allows for pꢀ ꢀ ꢀp
interaction between the rings C(52–57) and C(24–29) (dihedral
angle = 22.9(3)1, centroid separation = 4.408(5) A).
Conclusions
10,2-Bis(diphenylphosphino)ferrocene-1-carboxylic acid (Hdpc)
is a novel, planar-only chiral monofunctionalised derivative of
dppf, accessible in both enantiomeric forms via esters with
D-glucose diacetonide. The available data indicate that
Hdpc and dppf are structurally similar and show similar
coordination properties. Not surprisingly, the ee’s achieved
with Hdpc-based ligands in palladium-catalysed asymmetric
allylic alkylation fall into the range reported for BPPFA-
like4f,8a,36f and oxazolinyl-substituted dppf analogues.4b,10
The data so far collected during testing of chiral ferrocene
phosphino-carboxylic donors in asymmetric allylic alkylation
(ref. 15a–d and 16 and this work) consistently indicate that
phosphinocarboxamides are better ligands for this reaction
than their parent acids,45 and that planar chirality is the key
factor determining their catalytic efficiency. The rationale for
the somewhat lower ee’s attained with Hdpc-amides as
compared to amides based on III and IV (Scheme 1) can be
sought in their particular ligating properties (the number and
type of the donor atoms and their spatial distribution). First,
Hdpc-based ligands coordinate to palladium as practically
symmetric P,P-chelates and, hence, do not provide sufficient
electronic differentiation of the enantiotopic allylic termini
such in III-based amides that form P,O-chelates.15c Second,
the amide substituents are rather far away from the
Pd(Z3-allyl) unit and thus cannot efficiently control the access
of the nucleophile towards the coordinated allyl moiety. This
unfavourable situation could be improved (in principle) by
increasing the donor-asymmetry of Hdpc via different
substituents at the phosphorus atoms46 or by introduction of
a second directing moiety such in C2-symmetric ligands based
on acid IV.16
Similarly to 12a, the formation of (Rp)-16a leaves the ligand
geometry mostly unchanged except for conformational
reorganisation. Chelate coordination brings the phosphorus
substituents to an intermediate conformation, close to
syn-staggered (t = 301; the ideal value is 361). The ferrocene
unit is tilted by 2.3(3)1, exerts identical Fe–ring centroid
distances and symmetrically binds its functional substituents.
Assuming that the complex geometry remains largely
unchanged during the reaction (viz. least-motion principle44)
and that the ligand does not electronically differentiate the
allylic termini, the attack of the nucleophile can be expected to
occur preferentially from the less sterically hindered site, i.e. at
the carbon atom trans to phosphorus at the disubstituted Cp
ring (atom C45 in Fig. 8a). According to the generally
accepted mechanism,36 this would lead to the (R)-configured
product, which is indeed in line with the reaction outcome
(Scheme 7). The other, minor isomer may result from attack at
the second allylic terminus or by isomerisation of the reaction
intermediates as it is typical for allyl complexes. All
other isomeric Z3-allyl complexes, including the second most
probable endo–syn–syn Z3-allyl intermediate, are probably less
favoured for steric reasons and because of (partial) loss of
stabilisation through pꢀ ꢀ ꢀp interactions. The same very likely
applies also to the Pd(Z2-alkene) intermediates (Scheme 7)
directly resulting from the attack of the nucleophile.
Experimental
Materials and methods
The syntheses were performed under an argon atmosphere
with exclusion of the direct daylight. Tetrahydrofuran was
distilled from sodium–benzophenone ketyl. Acetone, dichloro-
methane and chloroform were dried over K2CO3 and distilled.
Acetonitrile was dried over P2O5 and distilled. Methanol was
distilled. Chloro-diphenylphosphine was distilled under
vacuum. Acid 2,9c 1,3-diphenylprop-2-en-1-yl acetate (13a),47
ethyl (1,3-diphenylprop-2-en-1-yl) carbonate (13b),48 and
di-m-chlorido-bis(Z3-1,3-diphenylallyl)dipalladium(II) (15)49 were
prepared following the literature procedures. Other chemicals
and solvents used in workup and in crystallisations were used
as received (Fluka and Aldrich).
NMR spectra were recorded with a Varian Unity Inova 400
spectrometer at 25 1C. Chemical shifts (d/ppm) are given
relative to internal SiMe4 (13C and 1H) or to external 85%
aqueous H3PO4 (31P). The assignment of the NMR signals is
based on conventional 1D and 2D (COSY, 13C gHSQC and
13C gHMBC) spectra. In addition to the standard notation of
the signal multiplicity, vt and vq are used to distinguish virtual
multiplets arising in the spin systems of the substituted
cyclopentadienyl (Cp) rings (Cy = cyclohexyl). Labelling
Scheme 7 Plausible reaction mechanism (Nu = nucleophile, LG =
leaving group).
schemes for Hdpc and glycosides 3 are presented in
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009
1556 | New J. Chem., 2009, 33, 1549–1562

View Article Online
1
(CDCl3): d 74.35 (d, JPC = 15 Hz, C-2), 74.80 (d, JPC
=
12 Hz, CH-20), 74.86 (CH-4), 75.40 (d, JPC = 12 Hz, CH-20),
75.34 (d, JPC = 16 Hz, CH-30), 75.68 (dd, JPC = 4 and ca.
1 Hz, CH-30), 76.02 (CH-5), 76.54 (d, JPC = 5 Hz, CH-3),
1
2
78.68 (d, JPC = 10 Hz, C-10), 80.32 (d, JPC = 17 Hz, C-1),
128.1–129.4 (m, CH of Ph), 132.19, 133.31, 133.39, 135.00
1
2
(4 ꢄ d, JPC = 20 Hz, CH of Ph); 137.25 (d, JPC = 12 Hz,
Cipso of Ph); 138.16 (virtual t, JPC = 10 Hz, Cipso of Ph),
1
138.88 (d, JPC = 12 Hz, Cipso of Ph), 174.80 (CQO). Note:
the assignment for C-1/2 may be interchanged. 31P{1H} NMR
(CDCl3): d ꢂ18.2 (s), ꢂ18.1 (s). IR (Nujol): nmax/cmꢂ1 1675s,
1583w, 1435s, 1310m, 1282m, 1257m, 1161m, 1070w, 1024w,
841m, 826m, 744vs, 696vs, 480m. MS: m/z ESI+ 621
([M + Na]+); ESIꢂ 597 ([M ꢂ H]ꢂ). HR MS (ESI+) calc.
Scheme 8 The labelling scheme adopted for (Rp)-Hdpc and (Rp)-3.
The (Sp)-isomers are labelled analogously.
for C35H2856FeO2P2Na ([M
621.0827.
+
Na]+) 621.0806, found
Scheme 8. IR spectra were recorded on an FT-IR Nicolet
Magna 650 spectrometer. Electrospray (ESI) mass spectra
were measured with a Thermo Scientific LTQ Orbitrap XL
or with a Bruker Esquire 3000 (only low-resolution spectra)
spectrometers. The composition of the ionic species was
corroborated by a comparison of the experimental and
calculated isotopic patterns. Optical rotations were determined
on an Autopol III polarimeter (Rudolph Research) at
room temperature. Melting points were determined on a
Kofler block.
Preparation and resolution of 1,2:5,6-di-O-isopropylidene-
a-D-3-glucofuranosyl 10,2-bis(diphenylphosphino)ferrocene-1-
carboxylates (3). 4-(Dimethylamino) pyridine (0.46 g,
3.73 mmol), 1,2:5,6-di-O-isopropylidene-a-D-3-glucofuranose
(1.17 g, 4.50 mmol), and N,N0-dicyclohexylcarbodiimide
(0.93 g, 4.50 mmol) were successively added to rac-Hdpc
(2.23 g, 3.73 mmol) suspended in dichloromethane (120 mL).
The resulting red solution was stirred at room temperature for
24 h, filtered and the volatiles were removed under vacuum.
The residue was purified by column chromatography on silica
gel using hexane–diethyl ether mixture with increasing polarity
(4 : 1 - 1 : 1 v/v). The first fraction yielded, after solvent
removal, 145 mg (5% yield) of rac-4 as a red amorphous
solid. Evaporation of the following major band afforded
2.77 g (88%) of a mixture of (Rp)- and (Sp)-3. Repeated
crystallisation (three times) of this mixture from diethyl
ether–hexane afforded analytically pure, orange crystalline
(Rp)-3. Combined yield of (Rp)-3: 1.10 g (35%; 70% of the
theoretical amount). The mother liquors from the crystal-
lisations were combined and chromatographed on silica gel
(hexane–diethyl ether, 4 : 1 v/v). The mixture of diastereo-
isomers eluted first (1.28 g, (Rp) : (Sp) E 15 : 85), followed by a
second band containing pure (Sp)-3 (amber glassy solid,
380 mg, 12%).
Syntheses
Racemic 10,2-bis(diphenylphosphino)ferrocene-1-carboxylic
acid (rac-Hdpc). n-Butyllithium (10 mL, 2.5 M in hexanes,
25 mmol) was added dropwise to a solution of rac-10,2-
dibromoferrocene-1-carboxylic acid (2; 2.77 g, 7.14 mmol) in
THF (60 mL) with stirring and cooling to ꢂ78 1C whereupon
the colour of the reaction mixture changed from orange to red.
The mixture was stirred at ꢂ78 1C for 2 h, and treated with
ClPPh2 (3.0 mL, 16.7 mmol). Stirring was continued at ꢂ78 1C
for 30 min and then at room temperature for 18 h. Then, the
reaction solution was mixed with 5% aqueous KOH (50 mL)
and the volatiles were removed under vacuum. The hetero-
geneous residue (aqueous phase containing an oily material)
was extracted with diethyl ether (2 ꢄ 30 mL) and then acidified
with concentrated phosphoric acid (to pH E 2). The
precipitated product was dissolved by addition of THF, the
organic phase was separated and the aqueous layer was
extracted with THF (3 ꢄ 50 mL). The combined organic
solutions were washed with brine, dried over MgSO4 and
evaporated under vacuum. The residue was purified by column
chromatography on silica gel (several runs). Elution with
dichloromethane–methanol (10 : 1 v/v) followed by evaporation
of the first fractions afforded pure rac-Hdpc as an orange
solid. Combined yield: 2.24 g (52%). The combined residua
(total 1.25 g) contained rac-Hdpc, Hdpf and rac-2-(diphenyl-
phosphino)ferrocenecarboxylic acid in ca. 1 : 3 : 4 molar ratio
according to NMR spectra.
Analytical data for (Rp)-3. Mp 183–186 1C dec. (diethyl
ether–hexane). [a]D +33 (c = 1.0, CHCl3). 1H NMR (CDCl3):
d 1.08 (s, 3 H, CMe2), 1.38 (s, 3 H, CMe2), 1.42 (s, 6 H, CMe2),
3.41 (ddd, J = 2.6, 1.6, 0.9 Hz, CH-3), 3.70 (d, 3JHH = 3.6 Hz,
1 H, CH-200), 4.02 (d of vq, 1 H, CH-20), 4.09 (dd, 3JHH = 8.8,
2
3
3.2 Hz, 1 H, CH-400), 4.11 (dd, JHH = 8.8, JHH = 3.9 Hz,
2
3
1 H, CH2-600), 4.26 (dd, JHH = 8.8, JHH = 6.1 Hz, 1 H,
CH2-600), 4.31 (ddd, J1 E J2 E 2.6, J3 E 0.4 Hz, 1 H, CH-4),
4.32 (d of vq, 1 H, CH-20), 4.62 and 4.66 (2 ꢄ dt, J = 2.4, 1.2
3
Hz, 1 H, CH-30); 4.67 (d, JHH = 3.6 Hz, 1 H, CH-100), 4.93
(dddd, 3JHH E 9.0, 6.0, 3.8, JPH E 3.8 Hz, 1 H, CH-500), 5.05
(ddd, J = 2.6, 1.6, 0.9 Hz, 1 H, CH-5), 7.09–7.39 (m, 20 H,
PPh2). 13C{1H} NMR (CDCl3): d 25.55 (CMe2, dH 1.38), 25.81
(CMe2, dH 1.08), 26.60 and 27.14 (CMe2, dH 1.42); 67.80
Analytical data for rac-Hdpc. Mp dec. above 190 1C. 1H
NMR (CDCl3): d 3.63 (ddd, J = 2.5, 1.5, 0.8 Hz, 1 H, CH-3),
3.88 and 4.30 (2 ꢄ d of vq, 1 H, CH-20), 4.34 (vt, J = 2.5 Hz,
1 H, CH-4), 4.51 and 4.53 (2 ꢄ d of vq, 1 H, CH-30); 5.00
(m, 1 H, CH-5), 7.10–7.46 (m, 20 H, PPh2). 13C{1H} NMR
1
(CH2-600), 72.79 (CH-500), 74.68 (d, JPC = 15 Hz, C-2),
3
74.80 (d, JPC = 3 Hz, CH-4), 75.00 (d, JPC = 13 Hz,
CH-20), 75.08 (d, JPC = 15 Hz, CH-20), 75.58 (dd, JPC = 4
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009 New J. Chem., 2009, 33, 1549–1562 | 1557

View Article Online
and 1 Hz, CH-30), 75.90 (CH-5), 76.02 (d, JPC = 8 Hz, CH-30),
76.05 (CH-300), ca. 76.9 (CH-3; obscured by the solvent signal),
78.51 (d, JPC = 10 Hz, C-10), 79.28 (d, JPC = 17 Hz, C-1),
80.15 (CH-400), 83.42 (CH-200), 104.90 (CH-100), 109.42 (CMe2,
C-5a00), 111.63 (CMe2, C-1a00), 128.0–129.3 (m, CH of Ph),
132.06 (d, JPC = 19 Hz, CH of Ph), 131.20 (d, JPC = 3 Hz, CH
(d, JPC = 13 Hz, CH of Cp), 75.96 (d, JPC = 16 Hz, CH of Cp),
76.38 (d, JPC = 7 Hz, Cipso of Cp), 76.44 (d, JPC = 9 Hz,
1
1
CH of Cp), 77.94 (d, JPC = 10 Hz, CH of Cp), 82.89 (d, JPC =
17 Hz, Cipso of Cp), 84.88 (d, JPC = 16 Hz, Cipso of Cp),
128.1–129.0 (m, CH of Ph), 132.9–133.5 (m, CH of Ph), 133.40
(d, JPC = 21 Hz, CH of Ph), 137.51 (d, JPC = 15 Hz, Cipso of
of Ph), 133.40 (d, JPC = 2 Hz, CH of Ph), 135.04 (d, JPC
1
=
Ph), 138.45 (virtual t, J = 9 Hz, Cipso of Ph), 139.58 (d, JPC =
22 Hz, CH of Ph), 137.44 (d, JPC = 13 Hz, Cipso of Ph),
138.21 (d, 1JPC = 10 Hz, Cipso of Ph), 139.43 (d, 1JPC = 15 Hz,
13 Hz, Cipso of Ph), 154.36 (NC(O)N), 170.71 (C(O)N).
31P{1H} NMR (CDCl3): d ꢂ20.6 (s), ꢂ17.7 (s). IR (Nujol):
3
Cipso of Ph), 170.13 (d, JPC = 3 Hz, CQO). 31P{1H} NMR
n
max/cmꢂ1 3261w, 1699vs, 1626w, 1517m, 1419w, 1316m,
1278w, 1176w, 1136w, 1000w, 832w, 768w, 747m, 696m,
(CDCl3): d ꢂ17.9 (s), ꢂ15.2 (s). IR (Nujol): nmax/cmꢂ1 1711s,
1584w, 1435s, 1320w, 1262m, 1166w, 1143m, 1071m, 1022m,
842m, 742m, 699m. MS: m/z ESI+ 841 ([M + H]+), 863
([M + Na]+). HR MS (ESI+) calc. for C47H4656FeO7P2Na
([M + Na]+) 863.1960, found 863.1962. Anal. calc. for
C47H46FeO7P2 (840.6): C 67.15, H 5.52%. Found C 66.82,
H 5.60%.
493m. MS: m/z ESI+ 827 ([M + Na]+), ESIꢂ 678
([M
ꢂ
CONHCy]ꢂ). HR MS (ESI+) calc. for
C48H5056FeO2N2P2Na ([M
+
Na]+) 827.2589, found
827.2597.
Preparation of (Rp)- and (Sp)-Hdpc. Glycoside (Rp)-3
(950 mg, 1.13 mmol) was dissolved in a mixture of THF
(30 mL) and methanol (30 mL). Aqueous KOH solution
(30 mL of 3 M in degassed water) was added, and the resulting
mixture was stirred at 50 1C for 22 h. After cooling to room
temperature, the reaction solution was acidified with H3PO4
(40% aq. solution). Diethyl ether (30 mL) and brine (30 mL)
were added, the organic phase was separated, and the aqueous
phase was extracted with diethyl ether (20 mL). The combined
extracts were washed with brine (2 ꢄ 30 mL), dried over
anhydrous MgSO4, and evaporated under vacuum. The
residue was dissolved in ethyl acetate, and passed through a
short alumina column, eluting with the same solvent. The
product remained adsorbed, while the recovered glucose
diacetonide eluted. Subsequent elution with methanol–acetic
acid mixture (95 : 5 v/v) afforded (Rp)-Hdpc as an orange solid
after removal of the solvents (512 mg, 76%). (Sp)-Hdpc was
obtained similarly starting from (Sp)-3 (250 mg, 0.30 mmol) in
69% isolated yield.
1
Analytical data for (Sp)-3. [a]D ꢂ240 (c = 1.0, CHCl3). H
NMR (CDCl3): d 1.07 (s, 3 H, C(1a00)Me2), 1.28 (s, 3 H,
C(5a00)Me2), 1.36 (s,
3 3 H,
H, C(5a00)Me2), 1.50 (s,
C(1a00)Me2), 3.56 (ddd, J E 1.0, 1.5, 2.4 Hz, 1 H, CH-3),
3.75 (m, 1 H, CH-20), 3.86 (dd, J = 8.5, 5.8 Hz, 1 H, CH-600),
3.93–4.02 (m, 2 H, CH-500 and -600), 4.12 (dd, J = 2.8, 8.8 Hz,
1 H, CH-400), 4.26 (vt, J = 2.4 Hz, 1 H, CH-4), 4.45 (d, J =
3.4 Hz, 1 H, CH-200), 4.46 (dt, J = 1.2, 2.4 Hz, 1 H, CH-30),
4.51 (m, 1 H, CH-20a), 4.66 (br m, 1 H, CH-30a), 5.04 (m, 1 H,
CH-5), 5.44 (d, J = 2.9 Hz, 1 H, CH-300), 5.94 (d, J = 3.7 Hz,
1 H, CH-100), 7.11–7.43 (m, 20 H, PPh2). 13C{1H} NMR
(CDCl3): d 25.14 (CMe2, dH 1.36), 26.32 (CMe2, dH 1.50),
26.89 (CMe2, dH 1.28), 27.15 (CMe2, dH 1.07), 67.37 (CH2-600),
2
71.96 (d, J = 3 Hz, CH-500), 74.13 (d, JPC = 7 Hz, CH-20),
3
74.54 (d, JPC = 2 Hz, CH-4), 75.19 (dd, JPC = 2 and 4 Hz,
1
CH-30), 75.28 (d, JPC = 16 Hz, C-2), 75.60 (CH-300),
75.79 (dd, JPC = 2 and 5 Hz, CH-30a), 75.97 (CH-5), 76.10
2
2
(d, JPC = 20 Hz, CH-20a), 76.30 (d, JPC = 5 Hz, CH-3),
78.59 (d, 1JPC = 10 Hz, CH-10), 79.57 (d, 2JPC = 18 Hz, CH-1),
80.00 (CH-400), 83.44 (CH-200), 105.27 (d, JPC E 1 Hz, CH-100),
109.41 (CH-5a00), 112.38 (CH-1a00), 128.0–128.3 (m, CH of
Ph), 128.47, 128.87 , 129.22 (3 ꢄ CH of Ph), 132.24, 132.91,
Analytical data. (Rp)-Hdpc: [a]D +189 (c = 1.0, CHCl3);
(Sp)-Hdpc: [a]D ꢂ187 (c = 1.0, CHCl3). NMR and ESI MS
spectra of (Rp)- and (Sp)-Hdpc were identical with those of the
racemic acid.
When the hydrolysis reaction was carried out at room
temperature with 268 mg of (Rp)-3, a mixture of products
was obtained that, after chromatography (silica gel, dichloro-
methane–methanol 10 : 1 v/v), gave two fractions. The first
fraction (30 mg) contained unreacted (Rp)-3 and methyl
(Rp)-10,2-bis(diphenylphosphino)ferrocene-1-carboxylate, (Rp)-5.
Recrystallisation of this fraction from diethyl ether–pentane
yielded a mixture of two types of crystals: red prisms and fine
yellow needles. The red crystals were manually separated and
crystallised once again to yield analytically pure (Rp)-5. The
second fraction from the chromatography (217 mg) contained
the acid and unreacted glycoside, and was processed as
described above.
133.71 (3 ꢄ d, JPC = 20 Hz, CH of Ph), 135.06 (d, JPC
=
22 Hz, CH of Ph), 137.53 (d, JPC = 13 Hz, Cipso of Ph),
137.63, 138.68 (2 ꢄ d, JPC = 10 Hz, Cipso of Ph), 139.30
(d, JPC = 12 Hz, Cipso of Ph), 169.39 (d, 3JPC = 3 Hz, CQO).
31P{1H} NMR (CDCl3): d ꢂ18.4 (s), ꢂ18.2 (s). IR (Nujol):
n
max/cmꢂ1 1719s, 1585w, 1435s, 1324w, 1259m, 1215w, 1163w,
1143m, 1074m, 1025m, 741m, 697m. HR MS (ESI+) calc. for
C47H4656FeO7P2Na ([M + Na]+) 863.1960, found 863.1962.
Analytical data for rac-4. 1H NMR (CDCl3): d 0.90–2.00
(m, 22 H, Cy CH2), 3.52 (m, 1 H, NHCy CH), 3.72 (m, 1 H,
C5H3), 3.84 (tt, J = 3.6, 11.9 Hz, 1 H, NCy CH), 3.93
(m, 1 H, C5H4), 4.17 (dd, J1 E J2 E 2.6 Hz, 1 H, C5H3),
4.27 (m, 1 H, C5H4), 4.53 (m, 1 H, C5H4), 4.59 (m, 1 H, C5H4),
4.62 (m, 1 H, C5H3), 6. (br d, J = 7.5 Hz, 1H, NH), 7.21–7.49
(m, 20 H, 2 ꢄ PPh2). 13C{1H} NMR (CDCl3): d 24.95, 24.98,
25.26, 25.55, 26.23, 26.43, 30.24, 31.28, 32.57, 33.11 (10 ꢄ CH2
of Cy); 49.86, 58.07 (2 ꢄ CH of Cy); 70.91 (CH of Cp),
72.14 (CH of Cp), 74.18 (d, JPC = 4 Hz, CH of Cp), 74.96
Analytical data for (Rp)-5. 1H NMR (CDCl3): d 3.54
(m, 1 H, C5H3), 3.65 (s, 3 H, CO2Me), 3.91 (m, 1 H, C5H4),
4.27 (vt, J = 2.6 Hz, 1 H, C5H3), 4.28 (m, 1 H, C5H4), 4.49
(m, 2 H, C5H4), 4.97 (m, 1 H, C5H3), 7.14–7.44 (m, 20 H,
2 ꢄ PPh2). 31P{1H} NMR (CDCl3): d ꢂ17.9 (s), ꢂ17.0 (s). IR
(Nujol): nmax/cmꢂ1 1714s, 1582w, 1318w, 1309w, 1264m,
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009
1558 | New J. Chem., 2009, 33, 1549–1562

View Article Online
1142m, 1067w, 1026w, 829w, 742s, 697s, 478m. HR MS
(ESI+) calc. for C36H3056FeO2P2Na ([M + Na]+) 635.0963,
found 635.0959.
(R,Rp)-10,2-Bis(diphenylphosphino)-1-[N-(1-phenyl-ethyl)-
carbamoyl]-ferrocene, (R,Rp)-8. Prepared from (R)-(1-phenyl-
ethyl)amine (13 mg). Yield: 61 mg (97%). [a]D +150 (c = 1.0,
CHCl3). 1H NMR (CDCl3): d 1.30 (d, 3J = 7.0 Hz, 3 H,
CHMePh), 3.53 (m, 1 H, C5H3), 3.64, 4.12, 4.18, 4.29 (4 ꢄ m,
1 H, C5H4), 4.30 (vt, J = 2.6 Hz, 1 H, C5H3), 5.05 (m, 1 H,
C5H3), 5.14 (m, 1 H, CHMePh), 7.12–7.48 (m, 25 H, 2 ꢄ PPh2,
and Ph), 7.59 (dd, J = 8.2, 12.8 Hz, 1 H, NH). 31P{1H} NMR
(CDCl3): d ꢂ20.3 (s), ꢂ17.8 (s). IR (RAS): nmax/cmꢂ1 3306w
br, 1648s, 1585w, 1523s, 1478m, 1434s, 1263w, 1160m, 743vs,
697vs, 486m. HR MS (ESI+) calc. for C43H3856FeNOP2
([M + H]+) 702.1773, found 702.1757.
General procedure for the preparation of amides 6–10.
N-[3-(Dimethylamino)propyl]-N0-ethylcarbodiimide (0.03 mL,
0.17 mmol) was added to an ice-cooled suspension of
(Rp)-Hdpc (54 mg, 0.09 mmol) and 1-hydroxybenzotriazole
(15 mg, 0.1 mmol) in dichloromethane (5 mL). After 5 min, a
solution of the appropriate amine (1.2 equiv.) in the same
solvent (1–2 mL) was introduced and the mixture was stirred
at room temperature for 20 h. Then, the reaction solution was
diluted with dichloromethane (10 mL); extracted successively
with 1 M HCl (5 mL), saturated aqueous hydrogen carbonate
(10 mL), and brine (10 mL); dried (MgSO4); and evaporated
under vacuum. The products were isolated by column
chromatography (silica gel, dichloromethane–methanol
20 : 1 v/v) and obtained as orange glassy solids after evaporation.
The yields were typically very good ( Z 95%), the exceptions
being the 2-hydroxyethyl ((Rp)-10, 78%) and diphenylmethyl
((Rp)-9, 65%) amides. In the latter case, intermediate benzo-
triazolyl ester (Rp)-11 was also isolated (31%).
(S,Rp)-10,2-Bis(diphenylphosphino)-1-[N-(1-phenyl-ethyl)-
carbamoyl]-ferrocene, (S,Rp)-8. Prepared from (S)-(1-phenyl-
ethyl)amine (13 mg). Yield: 60 mg (95%). [a]D +184 (c = 1.0,
CHCl3). 1H NMR (CDCl3): d 1.54 (d, 3J = 6.8 Hz, 3 H,
CHMePh), 3.53 (m, 1 H, C5H3), 3.74, 4.23 (2 ꢄ m, 1 H, C5H4),
4.28 (vt, J = 2.6 Hz, 1 H, C5H3), 4.39 (m, 2 H, C5H4), 5.05
(m, 1 H, C5H3), 5.19 (m, 1 H, CHMePh), 7.01–7.46 (m, 26 H,
2 ꢄ PPh2, CHMePh, and NH). 31P{1H} NMR (CDCl3):
d ꢂ20.4 (s), ꢂ17.9 (s). IR (RAS): nmax/cmꢂ1 3315w br,
1636s, 1523s, 1478m, 1433s, 1263m, 1160m, 1026m,
836w, 741vs, 695vs, 487m. HR MS (ESI+) calc. for
C43H3856FeNOP2 ([M + H]+) 702.1773, found 702.1766.
(Rp)-10,2-Bis(diphenylphosphino)-1-(N-isopropyl-carbamoyl)-
ferrocene, (Rp)-6. Prepared from isopropylamine (7 mg). Yield:
55 mg (96%). [a]D +203 (c = 1.0, CHCl3). 1H NMR (CDCl3):
d 0.98, 1.21 (2 ꢄ d, 3J = 6.5 Hz, 3 H, CHMe2), 3.53 (m, 1 H,
C5H3), 3.75 (m, 1 H, C5H4), 4.10 (m, 1 H, CHMe2), 4.26
(vt, J = 2.6 Hz, 1 H, C5H3), 4.27 (m, 1 H, C5H4), 4.37, 4.42
(2 ꢄ m, 1 H, C5H4), 4.99 (m, 1 H, C5H3), 6.89 (dd, J = 8.1,
10.9 Hz, 1 H, NH), 7.10–7.48 (m, 20 H, 2 ꢄ PPh2). 31P{1H}
NMR (CDCl3): d ꢂ20.1 (s), ꢂ17.8 (s). IR (RAS): nmax/cmꢂ1
3321w br, 1648vs, 1526s, 1478m, 1434s, 1266m, 1163m, 1026w,
834w, 741vs, 696vs, 487m. HR MS (ESI+) calc. for
C38H3656FeNOP2 ([M + H]+) 640.1616, found 640.1598.
(Rp)-10,2-Bis(diphenylphosphino)-1-(N,N-diphenyl-methyl-
carbamoyl)ferrocene, (Rp)-9. Starting with amino(diphenyl)-
methane (21 mg), the general procedure furnished a mixture of
products whose chromatographic separation (silica gel,
dichloromethane–methanol 50 : 1 v/v) gave two bands. After
evaporation, the first band afforded benzotriazolyl ester
(Rp)-11 (20 mg) and the second one provided pure amide
1
(Rp)-9 (45 mg, 65%). [a]D +191 (c = 1.0, CHCl3). H NMR
(CDCl3): d 3.52 (m, 1 H, C5H3), 3.64, 4.07, 4.15, 4.27 (4 ꢄ m,
1 H, C5H4), 4.33 (vt, J = 2.6 Hz, 1 H, C5H3), 5.13 (m, 1 H,
C5H3), 6.34 (dd, J = 2.5, 8.6 Hz, 1 H, NHCHPh2), 6.99–7.44
(m, 30 H, 2 ꢄ PPh2, and CHPh2), 8.07 (dd, J = 8.5, 13.1 Hz,
1 H, NH). 31P{1H} NMR (CDCl3): d ꢂ20.7 (s), ꢂ17.9 (s). IR
(RAS): nmax/cmꢂ1 3300w br, 1655s, 1585w, 1514s composite,
1434s, 1267w, 1159m, 1027m, 909m, 836w, 742vs, 700vs, 489s.
HR MS (ESI+) calc. for C48H4056FeNOP2 ([M + H]+)
764.1929, found 764.1928.
(Rp)-10,2-Bis(diphenylphosphino)-1-(N-benzyl-carbamoyl)-
ferrocene, (Rp)-7. Prepared from benzylamine (12 mg). Yield:
60 mg (97%). [a]D +188 (c = 1.0, CHCl3). 1H NMR (CDCl3):
d 3.59 (m, 1 H, C5H3), 3.67, 4.22 (2 ꢄ m, 1 H, C5H4), 4.30–4.34
(m, 3 H, C5H3 and C5H4), 4.50 (d, J = 5.8 Hz, 2 H,
NHCH2Ph), 5.05 (m, 1 H, C5H3), 7.06–7.46 (m, 26 H, 2 ꢄ
PPh2, CH2Ph, and NH). 13C{1H} NMR (CDCl3): d 43.60
(CH2Ph), 73.68 (d, J = 2 Hz, CH of Cp), 73.97 (m, CH of Cp),
75.01 (d, J = 4 Hz, CH of Cp), 75.40 (d, J = 6 Hz, CH of Cp),
75.77 (d, J = 17 Hz, CH of Cp), 76.19 (d, J = 11 Hz, Cipso of
Cp), 78.09 (d, J = 10 Hz, Cipso of Cp), 81.21 (d, J = 18 Hz,
Cipso of Cp), 127.11, 127.61 (2 ꢄ CH of Ph), 128.1–128.7
(m, CH of Ph), 129.68 (CH of Ph), 132.10 (d, J = 17 Hz, CH
of Ph), 133.12, 133.53 (2 ꢄ d, J = 20 Hz, CH of Ph), 135.04
(d, J = 21 Hz, CH of Ph), 135.79 (d, J = 7 Hz, Cipso of Ph),
137.89 (d, J = 10 Hz, Cipso of Ph), 137.93 (d, J = 7 Hz, Cipso
of Ph), 138.51 (d, J = 10 Hz, Cipso of Ph), 138.68 (Cipso of Ph),
(Rp)-10,2-Bis(diphenylphosphino)-1-[N-(2-hydroxyethyl)-
carbamoyl]ferrocene, (Rp)-10. Prepared as described above
from (2-hydroxyethyl)amine (7 mg). Yield: 45 mg (78%).
[a]D +267 (c = 1.0, CHCl3). 1H NMR (CDCl3): d 2.74
(br s, 1 H, OH), 3.45 (q, J = 5.1 Hz, 2 H, CH2), 3.60–3.70
(m, 3 H, C5H3, and CH2), 3.71 (m, 1 H, C5H4), 4.30–4.34
(m, 3 H, C5H3, and C5H4), 4.42 (m, 1 H, C5H4), 5.01 (m, 1 H,
C5H3), 7.10–7.49 (m, 21 H, 2 ꢄ PPh2, and NH). 31P{1H} NMR
(CDCl3): d ꢂ20.3 (s), ꢂ18.3 (s). IR (Nujol): nmax/cmꢂ1 3293w
br, 1629s, 1583w, 1531s, 1435vs, 1338m, 1307m, 1274m,
1160m, 1026m, 834w, 741vs, 695vs, 488m. HR MS (ESI+)
calc. for C37H3456FeNOP2 ([M + H]+) 642.1409, found
3
169.54 (d, JPC = 4 Hz, CONH). 31P{1H} NMR (CDCl3):
d ꢂ20.4 (s), ꢂ17.9 (s). IR (Nujol): nmax/cmꢂ1 3319w br, 1651m,
1633s, 1585w, 1544m composite, 1275w, 1161w, 1027w,
836w, 743s, 697vs, 498m. HR MS (ESI+) calc. for
C42H3556FeNOP2Na ([M + Na]+) 710.1436, found 710.1434.
642.1409; calc. for C37H3356FeNNaOP2 ([M
+
Na]+)
664.1228, found 664.1225.
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009 New J. Chem., 2009, 33, 1549–1562 | 1559

View Article Online
Analytical data for (Rp)-11. 1H NMR (CDCl3): d 3.85
(m, 1 H, C5H3), 4.08 (m, 1 H, C5H4), 4.54–4.57 (m, 2 H,
C5H3, and C5H4), 4.71, 4.93 (2 ꢄ m, 1 H, C5H4), 5.24 (m, 1 H,
C5H3), 6.94–6.97 (m, 1 H, C6H4N3), 7.15–7.48 (m, 22 H,
2 ꢄ PPh2 and C6H4N3), 7.99–8.02 (m, 1 H, C6H4N3).
31P{1H} NMR (CDCl3): d ꢂ18.4 (s), ꢂ18.1 (s). IR (RAS):
(ESI+) calc. for C57H4856FeNOP2Pd (the cation) 986.1590,
found 986.1613.
Asymmetric allylic alkylation—general procedure
Ligand (8 mmol), [{Pd(Z3-C3H5)Cl}2] (1.5 mg, 4 mmol), and
alkali metal acetate (16 mmol; if appropriate) were mixed with
dry dichloromethane (3 mL) and the mixture was stirred at
room temperature for 30 min. Allylic substrate (0.25 mmol;
63 mg of 13a or 71 mg of 13b) was introduced and
followed, after stirring for another 5 min, successively with
N,O-bis(trimethylsilyl)acetamide (BSA; 0.19 mL, 0.75 mmol)
and malonate (0.75 mmol; 0.09 mL of dimethyl malonate
or 0.17 mL of di-tert-butyl malonate). The resulting mixture
was stirred for 20 h and washed with saturated aqueous
NH4Cl (2 ꢄ 5 mL). The organic layer was separated,
dried over MgSO4 and concentrated under vacuum.
Purification by column chromatography (silica gel;
hexane–ethyl acetate 3 : 1 v/v) afforded the alkylation product
(or its mixture with unreacted substrate in the case of
incomplete conversion).
n
max/cmꢂ1 1782s, 1478w, 1434m, 1249w, 1087m, 1021w,
906w, 744vs, 698vs, 500m. HR MS (ESI+) calc. for
C41H3256FeN3O2P2 (M + H+) 716.1314, found 716.1312.
Dichlorido-[rac-10,2-bis(diphenylphosphino)-ferrocene-1-carboxylic
acid-j2P,P0]palladium(II) (12). A solution of rac-Hdpc (12 mg,
0.02 mmol) in chloroform (2 mL) was layered with a solution
of [PdCl2(cod)] (5.7 mg, 0.02 mmol) in the same solvent
(1 mL). After standing at room temperature for two days,
the deposited solid was filtered off and dried under vacuum to
give 12 as an orange microcrystalline solid (12 mg, 77%).
Crystals of 12ꢀMe2CO (12a) were obtained similarly by using
acetone as the solvent for [PdCl2(cod)].
1H NMR (DMSO-d6): d 3.69 (m, 1 H, C5H3), 4.03 (m, 1 H,
C5H4), 4.42 (m, 2 H, C5H3 and C5H4), 4.52 (m, 1 H, C5H4),
Enantiomeric excesses were determined from integration
of 1H NMR spectra recorded in C6D6 in the presence of
tris(3-trifluoroacetyl-d-camphorato)europium(III). Configuration
of the major enantiomer was assigned on the basis of optical
rotation of the mixture.50
4.57 (m, 1 H, C5H4), 5.19 (m, 1 H, C5H3), 7.25–8.20 (m, 20 H,
2
2 ꢄ PPh2). 31P{1H} NMR (DMSO-d6): d 33.5 (d, JPP
=
35 Hz), 43.7 (d, JPP = 35 Hz). IR (Nujol): nmax/cmꢂ1 3347w
br, 1703vs, 1680w, 1307w, 1257w, 1192w, 1148m, 1094m,
835w, 749m, 698s, 554m, 497m, 469m. MS: m/z ESI+ 739
([M ꢂ Cl]+), 761 ([M + Na ꢂ HCl]+). Anal. calc. for
C35H28FePdO2P2Cl2ꢀ0.15CHCl3 (793.6): C 53.20, H 3.58%.
Found C 53.02, H 3.50%.
2
X-Ray crystallography. Crystals suitable for X-ray
diffraction analysis were grown from hot aqueous acetic acid
(rac-Hdpc: orange needle, 0.10 ꢄ 0.15 ꢄ 0.40 mm), diethyl
ether–pentane ((Rp)-5: orange prism, 0.40 ꢄ 0.43 ꢄ 0.50 mm),
diethyl ether–hexane ((Rp)-3: orange needle, 0.05 ꢄ 0.08 ꢄ
0.27 mm), and from warm ethyl acetate ((Rp)-16a: orange
block, 0.06 ꢄ 0.12 ꢄ 0.21 mm). Crystals of 12a were selected
directly from the reaction batch (orange plate, 0.08 ꢄ 0.15 ꢄ
0.25 mm).
Preparation of (g3-1,3-diphenylallyl){(Rp)-10,2-bis(diphenyl-
phosphino)-1-(N-benzylcarbamoyl)ferrocene-j2P,P0}palladium(II)
perchlorate, (Rp)-16. A suspension of amide (Rp)-7 (14 mg,
20 mmol) and 15 (6.7 mg, 10 mmol) in dichloromethane (3 mL)
was stirred at room temperature for 15 min, yielding a clear
solution. A solution of AgClO4 in acetonitrile (0.1 mL of
0.2 M solution, 0.02 mmol) was then added and stirring was
continued for 1 h. The formed precipitate (AgCl) was filtered
off (PTFE syringe filter, 0.45 mm pore size) and the filtrate was
evaporated under vacuum to yield (Rp)-16 as a yellow solid
(21 mg).
The diffraction data (ꢃhꢃkꢃl; 2y r 50.81 for (Rp)-3, 551 for
other compounds) were collected with a Nonius KappaCCD
diffractometer equipped with a Cryostream Cooler (Oxford
Cryosystems) using graphite monochromatised MoKa
radiation (l = 0.71073 A). The solvent molecules in the
structure of (Rp)-16a were disordered and, hence, their
contribution to the overall diffraction intensity was removed
by the SQUEEZE routine51 incorporated in the PLATON
program.52
The structures were solved by direct methods (SIR9753) and
refined by full-matrix least squares procedure based on F2
(SHELXL9754). The non-hydrogen atoms were refined with
anisotropic displacement parameters. Carboxylic hydrogens
(H2) in the structures of rac-Hdpc and 12a were located on
electron density maps and refined as riding atoms. All other
hydrogen atoms were included in their calculated positions
and refined as riding atoms. Selected crystallographic data are
given in Table 6. Geometric parameters and structural
drawings were obtained with a recent version of the PLATON
program. The calculated values are rounded with respect to
their estimated uncertainties (esd’s) given with one decimal;
parameters involving atoms in calculated positions are given
without esd’s.
1H NMR (CDCl3): d 3.48 (m, 1 H, C5H4), 3.96 (m, 1 H,
C5H4), 4.13 (m, 1 H, C5H3), 4.26 (m, 1 H, C5H4), 4.36 (vt, J =
2.8 Hz, 1 H, C5H3), 4.65–4.75 (m, 3 H, CH2Ph, CH allyl, and
C5H4), 5.20–5.33 (m, 2 H, CH2Ph, and CH allyl), 5.64 (m, 1 H,
C5H3), 6.45–7.70 (m, 26 H, 5 ꢄ Ph, and CH-meso allyl), 8.38
(dd, J = 5.0 Hz, 6.8 Hz, 1 H, NH). 13C{1H} NMR (CDCl3);
selected signals: d 72.19 (d, J = 6 Hz), 73.10 (d, J = 5 Hz),
73.66 (d, J = 6 Hz), 74.13 (d, J = 10 Hz), 75.23 (d, J = 4 Hz),
79.34 (d, J = 7 Hz), 81.40 (d, J = 11 Hz) (7 ꢄ CH of ferrocene
moiety); 91.16 (d, J = 26 Hz, CH allyl), 93.63 (d, J = 23 Hz,
CH allyl), 110.68 (m, CH-meso allyl), 170.04 (CO). 31P{1H}
2
NMR (CDCl3): d 21.3, 30.0 (2 ꢄ d, JPP = 61 Hz, PPh2). IR
(Nujol): nmax/cmꢂ1 3356w br, 1628m, 1582w, 1536m, 1438s,
1339w, 1270w, 1165w, 1096vs composite, 1028w, 747m, 694s,
624m, 493m. IR (0.02 M in CDCl3): nmax/cmꢂ1 3366w br,
1625m, 1540m, 1437m, 1271w, 1097s. MS: m/z ESI+ 986
([M ꢂ ClO4]+), 793 ([M ꢂ ClO4 ꢂ Ph2C3H3]+). HR MS
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009
1560 | New J. Chem., 2009, 33, 1549–1562

View Article Online
Table 6 Crystallographic data, data collection and structure refinement parameters for rac-Hdpc, (Rp)-5, (Rp)-3, 12a, and (Rp)-16a
Compound
rac-Hdpc
35H28FeO2P2
598.36
Monoclinic
P21/c (no. 14)
150(2)
(Rp)-5
(Rp)-3
12a
(Rp)-16a
Formula
M/g molꢂ1
Crystal system
Space group
T/K
C
C36H30FeO2P2
612.39
Monoclinic
P21 (no. 4)
150(2)
C47H46FeO7P2
840.63
Monoclinic
C2 (no. 5)
150(2)
C38H34Cl2FeO3P2Pdd
833.74
Triclinic
C65H64ClFeNO9P2Pdf
1262.81
Monoclinic
P21 (no. 4)
150(2)
ꢀ
P1 (no. 2)
150(2)
a/A
b/A
c/A
a/1
9.0484(2)
17.9216(3)
8.8899(2)
—
95.942(1)
—
1433.86(5)
2
1.386
0.669
22442
3284/2721
3.3
3.47
4.52, 9.25
NA
9.0257(2)
17.9691(3)
9.0278(2)
—
94.440(1)
—
1459.77(5)
2
1.393
0.659
22122
6607/6300
3.6
3.88
3.14, 8.30
0.02(1)
0.57, ꢂ0.52
700754
34.878(1)
8.5038(2)
14.9636(4)
—
110.062(1)
—
4168.8(2)
4
1.339
0.490
28497
7640/6905
5.2
3.31
4.17, 7.18
ꢂ0.01(1)
0.38, ꢂ0.27
700755
10.7792(2)
10.9451(2)
16.5867(3)
70.8340(9)
82.3917(9)
68.1648(9)
1715.69(5)
2
1.614
1.234e
48729
7885/6876
3.8
2.86
13.0501(7)
14.616(1)
16.703(1)
—
111.357(5)
—
b/1
g/1
V/A3
2967.2(3)
2
1.413
Z
Dcalc/g mLꢂ1
m(Mo Ka)/mmꢂ1
Diffractions total
Unique/obsda diffrns
Rint(%)b
0.704g
21194
11769/9534
4.2
4.93
6.81, 10.9
0.00(2)
R (observed data) (% )c
R, wR (all data) (%)c
Flack’s parameter
Dr/e Aꢂ3
3.64, 6.83
NA
0.39, ꢂ0.32
1.09, ꢂ0.67
0.69, ꢂ0.60
CCDC entry
700753
700756
700757
a
b
2
Diffractions with Io 4 2s(Io) were regarded as observed. Rint = S|Fo ꢂ Fo2(mean)|/SFo2, where Fo2(mean) is the average intensity of
symmetry-equivalent diffractions. R = S||Fo| ꢂ |Fc||/S|Fo|, wR = [S{w(Fo ꢂ Fc2)2}/Sw(Fo2)2]1/2
.
C35H28Cl2FeO2P2PdꢀC3H6O. Corrected
c
2
d
e
f
g
for absorption; range of transmission coefficients = 0.738–0.904. [C57H48FeO5P2Pd]ClO4ꢀ2C4H8O2. Corrected for absorption; range of
transmission coefficients = 0.911–0.965.
Chiral Ferrocenyl Ligands for Asymmetric Catalysis, in Metallo-
cenes, ed. A. Togni, R. L. Halterman, Wiley-VCH, Weinheim,
1998, vol. 2, ch. 11, pp. 685–721; (f) T. Hayashi, Asymmetric
Acknowledgements
We thank Dr A. Ruzicka and Dr Z. Padelkova for recording
´
Catalysis with Chiral Ferrocenylphosphine Ligands, in Ferrocenes:
Homogeneous Catalysis, Organic Synthesis, Materials Science,
ed. A. Togni, T. Hayashi, VCH, Weinheim, 1995, ch. 2, pp. 105–142.
5 D. Marquarding, H. Klusacek, G. Gokel, P. Hoffmann and I. Ugi,
J. Am. Chem. Soc., 1970, 92, 5389.
6 (a) T. Hayashi, K. Yamamoto and M. Kumada, Tetrahedron Lett.,
1974, 15, 4405; (b) T. Hayashi, T. Mise, S. Mitachi, K. Yamamoto
and M. Kumada, Tetrahedron Lett., 1976, 17, 1133.
7 T. Hayashi, T. Mise, M. Fukushima, M. Kagotani, N. Nagashima,
Y. Hamada, A. Matsumoto, S. Kawakami, M. Konishi,
K. Yamamoto and M. Kumada, Bull. Chem. Soc. Jpn., 1980, 53,
1138.
8 (a) T. Hayashi, Pure Appl. Chem., 1988, 60, 7; (b) T. Hayashi and
M. Kumada, Acc. Chem. Res., 1982, 15, 395; (c) See also
ref. 4c–f,36f.
the X-ray diffraction data for (Rp)-16a. This work is a part of
research projects supported by the Ministry of Education of
the Czech Republic (project nos. MSM0021620857 and
LC06070).
References
1 G. P. Sollot, J. L. Snead, S. Portnoy, W. R. Peterson and
H. E. Mertwoy, U. S. Department of Commerce, Office of Technical
Services, PB Report, 1965, vol. II, pp. 441–452 (Chem. Abstr.,
1965, 63, 18174).
2 (a) S. W. Chien and T. S. A. Hor, The Coordination and
Homogenous Catalytic Chemistry of 1,10-Bis(diphenylphosphino)-
ferrocene and its Chalcogenide Derivatives, in Ferrocenes: Ligands,
Materials and Biomolecules, ed. P. Stepnicka, Wiley, Chichester,
2008, ch. 2, pp. 33–116; (b) T. J. Colacot, Platinum Met. Rev., 2001,
45, 22; (c) G. Bandoli and A. Dolmella, Coord. Chem. Rev., 2000,
209, 161; (d) K.-S. Gan and T. S. A. Hor, 1,10-Bis(diphenyl-
phosphino)ferrocene—Coordination Chemistry, Organic Syntheses,
and Catalysis, in Ferrocenes: Homogeneous Catalysis, Organic
Synthesis, Materials Science, ed. A. Togni and T. Hayashi, VCH,
Weinheim, 1995, ch. 1, pp. 3–104.
9 (a) I. R. Butler and W. R. Cullen, Organometallics, 1986, 5, 2537;
(b) I. R. Butler, L. J. Hobson, S. M. E. Macan and D. J. Williams,
Polyhedron, 1993, 12, 1901; (c) I. R. Butler, S. Mussig and
M. Plath, Inorg. Chem. Commun., 1999, 2, 424.
¨
10 (a) O. B. Sutcliffe and M. R. Bryce, Tetrahedron: Asymmetry, 2003,
14, 2297; (b) C. J. Richards and A. J. W. Locke, Tetrahedron:
Asymmetry, 1998, 9, 2377; (c) L.-X. Dai, T. Tu, S.-L. You,
W.-P. Deng and X.-L. Hou, Acc. Chem. Res., 2003, 36, 659.
11 P. Stepnicka, Eur. J. Inorg. Chem., 2005, 3787.
12 (a) M. Lamac, I. Cı
2007, 2274; (b) P. Stepnicka, J. Schulz, I. Cı
K. Fejfarova, Collect. Czech. Chem. Commun., 2007, 72, 453;
(c) J. Kuhnert, M. Dusek, J. Demel, H. Lang and P. Stepnicka,
´
sarova
´
and P. Stepnicka, Eur. J. Inorg. Chem.,
3 T. J. Colacot and S. Parisel, Synthesis, Coordination Chemistry and
Catalytic Use of dppf Analogs, in Ferrocenes: Ligands, Materials
and Biomolecules, ed. P. Stepnicka, Wiley, Chichester, 2008, ch. 3,
pp. 117–140.
´
sarova and
´
´
¨
Dalton Trans., 2007, 2802; (d) J. Kuhnert, M. Lamac, T. Ruffer,
4 (a) H.-U. Blaser, W. Chen, F. Camponovo and A. Togni, Chiral
1,2-Disubstituted Ferrocene Diphosphines for Asymmetric
Catalysis, in Ferrocenes: Ligands, Materials and Biomolecules,
ed. P. Stepnicka, Wiley, Chichester, 2008, ch. 6, pp. 205–235;
(b) P. Stepnicka and M. Lamac, Synthesis and Catalytic Use of
Planar Chiral and Polydentate Ferrocene Donors, in Ferrocenes:
Ligands, Materials and Biomolecules, ed. P. Stepnicka, Wiley,
Chichester, 2008, ch. 7, pp. 237–277; (c) R. C. J. Atkinson,
V. C. Gibson and N. J. Long, Chem. Soc. Rev., 2004, 33, 313;
(d) T. J. Colacot, Chem. Rev., 2003, 103, 3101; (e) A. Togni, New
¨
¨
B. Walfort, P. Stepnicka and H. Lang, J. Organomet. Chem., 2007,
692, 4303; (e) C. Bianchini, A. Meli, W. Oberhauser,
A. M. Segarra, E. Passaglia, M. Lamac and P. Stepnicka, Eur. J.
Inorg. Chem., 2008, 441; (f) J. Kuhnert, M. Lamac, J. Demel,
¨
A. Nicolai, H. Lang and P. Stepnicka, J. Mol. Catal. A: Chem.,
2008, 285, 41; (g) J. Kuhnert, I. Cı
´
P. Stepnicka, Dalton Trans., 2008, 2454.
´
sarova, M. Lamac and
¨
13 J. Podlaha, P. Stepnicka, I. Cı
´
metallics, 1996, 15, 543.
sarova
´
and J. Ludvık, Organo-
´
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009 New J. Chem., 2009, 33, 1549–1562 | 1561

View Article Online
14 (a) S.-L. You, X.-L. Hou, L.-X. Dai, B.-X. Dao and J. Sun, Chem.
Commun., 2000, 1933; (b) J. M. Longmire, B. Wang and X. Zhang,
Tetrahedron Lett., 2000, 41, 5435; (c) P. Stepnicka, New J. Chem.,
2002, 26, 567; (d) B. Breit and D. Breuninger, Synthesis, 2005,
2782.
15 For applications, see: (a) ref. 14a–b; (b) S.-L. You, Y.-M. Luo,
W.-P. Deng, X.-L. Hou and L.-X. Dai, J. Organomet. Chem., 2001,
´ ´
637–639, 845; (c) M. Lamac, J. Tauchman, I. Cısarova and
plane comprising these atoms, moved away from the carboxyl
group.
35 The Cp rings are tilted by 2.3(2)1 and bind symmetrically to the iron
atom (D(Fe–Cg) = 0.014 A). The asymmetry in functional group
attachment is diminished compared to free Hdpc (D E 11 for C(2/5)-
C1-C11, and D E 11 for C(1/3)-C2-P1 and C(7/10)-C6-P2 angles).
36 (a) B. M. Trost and D. L. Van Vranken, Chem. Rev., 1996, 96, 395;
(b) B. M. Trost and M. L. Crawley, Chem. Rev., 2003, 103, 2921;
(c) B. M. Trost and C. Lee, Asymmetric Allylic Alkylation Reac-
tions, in Catalytic Asymmetric Synthesis, ed. I. Ojima, Wiley-VCH,
New York, 2nd edn, 2000, ch. 8E, pp. 593–650; (d) G. Helmchem
and A. Pfaltz, Acc. Chem. Res., 2000, 33, 336; (e) G. Helmchem,
J. Organomet. Chem., 1999, 576, 203; (f) T. Hayashi, Asymmetric
Allylic Substitution and Grignard Cross-Coupling, in Catalytic
Asymmetric Synthesis, ed. I. Ojima, VCH, New York, 1993,
ch. 7.1, pp. 325-365.
P. Stepnicka, Organometallics, 2007, 26, 5042; (d) S.-L. You,
X.-L. Hou and L.-X. Dai, J. Organomet. Chem., 2001, 637–639,
762; (e) S.-L. You, X.-L. Hou, L.-X. Dai and X.-Z. Zhu, Org.
Lett., 2001, 3, 149; (f) J. M. Longmire, B. Wang and X. Zhang,
J. Am. Chem. Soc., 2002, 124, 13400; (g) B. Breit and
D. Breuninger, J. Am. Chem. Soc., 2004, 126, 10244; (h) B. Breit
and D. Breuninger, Eur. J. Org. Chem., 2005, 3916; (i) B. Breit and
D. Breuninger, Synthesis, 2005, 147.
16 Only esters and amides of IV are known: (a) W. Zhang, T. Kida,
Y. Nakatsuji and I. Ikeda, Tetrahedron Lett., 1996, 37, 7995;
(b) W. Zhang, T. Shimanuki, T. Kida, Y. Nakatsuji and
I. Ikeda, J. Org. Chem., 1999, 64, 6247; (c) R. S. Laufer,
U. Veith, N. J. Taylor and V. Snieckus, Org. Lett., 2000, 2, 629.
17 For examples of the resolution of carboxylic acids via D-glucose
diacetonide esters, see: (a) J. Svoboda, K. Capek and J. Palecek,
Collect. Czech. Chem. Commun., 1987, 52, 766; (b) A. Netscher and
I. Gautschi, Liebigs Ann. Chem., 1992, 543; (c) O. I. Kolodiazhnyi
and E. V. Griskun, Tetrahedron: Asymmetry, 1996, 7, 967.
18 M. Lamac, J. Cvacka and P. Stepnicka, J. Organomet. Chem.,
2008, 693, 3430.
19 Column chromatography is usually not sufficient for a complete
separation of the diastereoisomers, affording only mixtures with
gradually increasing (Sp)-3/(Rp)-3 ratios. Chromatography
combined with crystallisation is a much more efficient resolution
method.
37 (a) U. Leutenegger, G. Umbricht, C. Fahrni, P. von Matt and
A. Pfaltz, Tetrahedron, 1992, 48, 2143; (b) B. M. Trost and
D. J. Murphy, Organometallics, 1985, 4, 1143; (c) M. T. El Gihani
and H. Heaney, Synthesis, 1998, 357.
38 Definition: ee = ([R] ꢂ [S])/([R] + [S]). Positive ee values indicate
that (R)-15 is the dominant product.
39 For introductory reviews, see: (a) C. Girard and H. B. Kagan, Angew.
Chem., Int. Ed., 1998, 37, 2922; (b) H. B. Kagan, Synlett, 2001, 888.
40 For selected examples of (Z3-allyl)palladium(II) complexes with
P,P-chelating ferrocene ligands, see: (a) P. Barbaro, P. S. Pregosin,
R. Salzmann, A. Albinati and R. W. Kunz, Organometallics, 1995,
14, 5160; (b) U. Burckhardt, V. Gramlich, P. Hofmann, R. Nesper,
P. S. Pregosin, R. Salzmann and A. Togni, Organometallics, 1996,
15, 3496; (c) S.-L. You, X.-L. Hou, L.-X. Dai, Y.-H. Yu and
W. Xia, J. Org. Chem., 2002, 67, 4684; (d) T. Tu, Y.-G. Zhou,
X.-L. Hou, L.-X. Dai, X.-C. Dong, Y.-H. Yu and J. Sun,
Organometallics, 2003, 22, 1255; (e) T. Sturm, B. Abad,
20 B. Schetter and B. Speiser, J. Organomet. Chem., 2004, 689, 1472.
21 1H NMR data: (a) A. De Bruyn, D. Danneels, M. Anteunis and
E. Saman, J. Carbohydr., Nucleosides Nucleotides, 1975, 2, 227; 13C
NMR data: (b) D. M. Vyas, H. C. Jarrell and W. A. Szarek, Can. J.
Chem., 1973, 53, 2748.
22 The observed distance is comparable with the sum of the van der
Waals radii (2.89 A). The radii were taken from the CCDC web
site: http://www.ccdc.cam.ac.uk/products/csd/radii/ (retrieved on
August 5, 2008).
W. Weissensteiner, K. Mereiter, B. R. Manzano and F. A. Jalon,
´
J. Organomet. Chem., 2006, 225, 209; (f) C.-W. Cho, J.-H. Son and
K.-H. Ahn, Tetrahedron: Asymmetry, 2006, 17, 2240.
41 U. Nettekoven, M. Widhalm, H. Kalchhauser, P. C. J. Kamer,
P. W. N. M. van Leeuwen, M. Lutz and A. L. Spek, J. Org. Chem.,
2001, 66, 759.
42 (a) C. A. Hunter and J. K. M. Sanders, J. Am. Chem. Soc., 1990,
112, 5525. See also: (b) C. A. Hunter, K. R. Lawson, J. Perkins and
C. J. Urch, J. Chem. Soc., Perkin Trans. 2, 2001, 651.
43 The centroidꢀ ꢀ ꢀcentroid distance in hexagonal graphite (space
group P63/mmm) is ca. 3.65 A. P. Trucano and R. Chen, Nature,
1975, 258, 136.
44 (a) F. O. Rice and E. Teller, J. Chem. Phys., 1938, 6, 489 (erratum:
F. O. Rice and E. Teller, J. Chem. Phys., 1939, 7, 199); (b) J. Hine,
Adv. Phys. Org. Chem., 1977, 15, 1.
45 In the presence of BSA, the carboxyl group of the free acid ligand
can be expected to be (at least partially) converted to the silyl ester.
46 This was already demonstrated for 10,2-bis(phosphine)-1-
oxazolinylferrocenes. T. Tu, X.-L. Hou and L.-X. Dai,
J. Organomet. Chem., 2004, 689, 3847.
23 H.-B. Kraatz, J. Inorg. Organomet. Polym. Mater., 2005, 15, 83.
24 For examples involving ferrocene phosphinocarboxylic acids, see:
(a) Ref. 12a–c, f, g; (b) L. Meca, D. Dvorak, J. Ludvık, I. Cısarova
´ ´ ´ ´
and P. Stepnicka, Organometallics, 2004, 23, 2541.
25 Formation of the related Hdpf-benzotriazolyl ester was noted
during the reaction of Hdpf with 1,2-diaminoethane in the presence
of EDC and HOBt (see ref. 12b).
26 Dppf crystallises with the symmetry of the monoclinic space group
P21/a with the Fe atom residing on the inversion centre.
27 U. Casellato, D. Ajo, G. Valle, B. Corain, B. Longato and
R. Graziani, J. Crystallogr. Spectrosc. Res., 1988, 18, 583.
28 P. Stepnicka and I. Cı
´
sarova
´
, New J. Chem., 2002, 26, 567.
47 Acetate 14a was prepared by acetylation of commercial racemic
1,3-diphenylallyl alcohol: I. D. G. Watson, S. A. Styler and
A. K. Yudin, J. Am. Chem. Soc., 2004, 126, 5086.
48 F. Ferioli, C. Fiorelli, G. Martelli, M. Monari, D. Savoia and
P. Tobaldin, Eur. J. Org. Chem., 2005, 1416.
49 T. Hayashi, A. Yamamoto, Y. Ito, E. Nishioka, H. Miura and
K. Yanagi, J. Am. Chem. Soc., 1989, 111, 6301.
50 T. Hayashi, A. Yamamoto, T. Hagihara and Y. Ito, Tetrahedron
Lett., 1986, 27, 191.
29 The difference between P1-C2-C(1/3) angles is ca. 31 while the
C(5/2)-C1-C11 and P2-C6-C(7/10) angles differ by ca. 71 in the
pairs. The pivotal phosphorus atoms (P1 and P2) are displaced by
ca. 0.1 A from the least-squares planes of their bonding cyclo-
pentadienyl rings. By contrast, the C11 atom is coplanar with the
Cp1 ring within 0.01 A and the carboxyl group is rotated by
81 from the Cp1 plane.
30 (a) W. H. Ojala, W. B. Gleason, M. P. E. Connelly and
R. R. Wallis, Acta Crystallogr., Sect. C: Cryst. Struct. Commun.,
1996, 52, 155; (b) J. Sheville, D. Berndt, T. Wagner and P. Norris,
J. Chem. Crystallogr., 2003, 33, 409.
31 The differences are below ca. 0.1 A for the bond lengths and
typically ca. 2–31 for the angles.
32 T. Hayashi, M. Konishi, Y. Kobori, M. Kumada, T. Higuchi and
K. Hirotsu, J. Am. Chem. Soc., 1984, 106, 158.
33 I. R. Butler, W. R. Cullen, J.-T. Kim, S. J. Rettig and J. Trotter,
Organometallics, 1985, 4, 972.
51 P. van der Sluis and A. L. Spek, Acta Crystallogr., Sect. A:
Fundam. Crystallogr., 1990, 46, 194.
52 A. L. Spek, Platon—a multipurpose crystallographic tool, Utrecht
University, Utrecht, The Netherlands, 2003 and updates. For
reference, see: A. L. Spek, J. Appl. Crystallogr., 2003, 36, 7.
53 A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano,
C. Giacovazzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori
and R. Spagna, J. Appl. Crystallogr., 1999, 32, 115.
54 G. M. Sheldrick, SHELXL97. Program for Crystal Structure
Refinement from Diffraction Data, University of Gottingen,
Germany, 1997.
34 Pd, Cl2, P1, and P2 are coplanar within ca. 0.02 A. The remaining
donor atom, Cl1, is displaced by 0.163(1) A from the least-squares
¨
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009
1562 | New J. Chem., 2009, 33, 1549–1562