Preparation of chiral phosphinoferrocene carboxamide ligands and their application to palladium-catalyzed asymmetric allylic alkylation

Article abstract of DOI:10.1021/om700542s

A series of phosphinoferrocene carboxamides bearing achiral (benzyl) and chiral [(R)- and (S)-1phenylethyl] substituents at the amide nitrogen have been prepared from 1′-(diphenylphosphino)ferrocenecarboxylic (Hdpf) and (S _p)-2-(diphenylphosphino)ferrocenecarboxylic ((S_p)-1) acids and tested as ligands for enantioselective allylic alkylation of 1,3-diphenylallyl acetate with dimethyl malonate. At room temperature, the alkylation reactions proceeded with complete conversions and ee's up to 90%, the most efficient being the planar-only chiral ligand (S_p)-2- (diphenylphosphino)-l-(N-benzylcarbamoyl)ferrocene ((S_p)-2). The crystal structures of (S_p)-2 and the cationic (η³- allyl)palladium(II) complex [Pd(η³-1,3-Ph₂C ₃H₃){(S_p)-2-K²O,.P}]ClO₄ ((S_p)-8) have been determined by single-crystal X-ray diffraction and solution NMR data were obtained to provide an insight into the mechanism of chiral discrimination.

Full text of DOI:10.1021/om700542s

5042
Organometallics 2007, 26, 5042-5049
Preparation of Chiral Phosphinoferrocene Carboxamide Ligands
and Their Application to Palladium-Catalyzed Asymmetric Allylic
Alkylation
Martin Lamacˇ, Jirˇ´ı Tauchman, Ivana C´ısarˇova´, and Petr Sˇteˇpnicˇka*
Department of Inorganic Chemistry, Faculty of Natural Science, Charles UniVersity in Prague,
HlaVoVa 2030, 12840 Prague, Czech Republic
ReceiVed June 1, 2007
A series of phosphinoferrocene carboxamides bearing achiral (benzyl) and chiral [(R)- and (S)-1-
phenylethyl] substituents at the amide nitrogen have been prepared from 1′-(diphenylphosphino)-
ferrocenecarboxylic (Hdpf) and (Sp)-2-(diphenylphosphino)ferrocenecarboxylic ((Sp)-1) acids and tested
as ligands for enantioselective allylic alkylation of 1,3-diphenylallyl acetate with dimethyl malonate. At
room temperature, the alkylation reactions proceeded with complete conversions and ee’s up to 90%, the
most efficient being the planar-only chiral ligand (Sp)-2-(diphenylphosphino)-1-(N-benzylcarbamoyl)-
ferrocene ((Sp)-2). The crystal structures of (Sp)-2 and the cationic (η3-allyl)palladium(II) complex [Pd-
(η3-1,3-Ph2C3H3){(Sp)-2-κ2O,P}]ClO4 ((Sp)-8) have been determined by single-crystal X-ray diffraction
and solution NMR data were obtained to provide an insight into the mechanism of chiral discrimination.
5
axially chiral biaryl phosphinoethers6 and phosphino-phos-
Introduction
phine oxides,7 are well established.
Asymmetric allylic alkylation represents one of the most
powerful methods available for the construction of new carbon-
carbon bonds in a stereoselectiVe manner. Many efficient
catalytic systems based on combinations of different metals and
chiral ligands have been reported to date that allow for
performing allylic alkylation with high enantioselectivities and
with a wide choice of allylic substrates and nucleophiles.1 Chiral
ferrocene donors have been successfully employed as ligands
for this reaction, the most thoroughly studied being bidentate
donors of the P,P-, P,N-, and P,S-types.2 By contrast, ligands
of the P,O-type are still rather scarce, although their “organic”
analogues, e.g., Trost’s diamido diphosphine chiral ligands1a-c,3
and their donor-unsymmetric analogues,4 phosphinoamides,5 and
The prominent examples of ferrocene P,O-ligands utilized
in asymmetric allylic alkylation (Scheme 1) include C2-
symmetric 1,1′-bis(diphenylphosphino)-2,2′-bis(alkoxycarbon-
yl)ferrocenes and their related bis(N-ω-hydroxyalkyl)diamides
(I, Y ) OR and NH(CH2)nOH),8 Trost-type ligands II,9
phosphinoferrocene acetals III (n ) 0, 1 and R1/R2 ) Me or
H; the series includes both (Sp)- and (Rp)-derivatives),10 and
amides derived from Ugi’s amine (IV).11
Recently, we have reported the synthesis of a new phosphi-
noferrocenecarboxylic ligand12 combining planar and central
chirality, (R,Rp)-2-[1-(diphenylphosphino)ethyl]ferrocenecarboxylic
acid (V). Testing of acid V and amides thereof as ligands for
palladium-catalyzed asymmetric allylic alkylation has shown
that the degree of asymmetric induction changes greatly with
* To whom correspondence should be addressed. E-mail: stepnic@
natur.cuni.cz.
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10.1021/om700542s CCC: $37.00 © 2007 American Chemical Society
Publication on Web 08/25/2007

Chiral Phosphinoferrocene Carboxamide Ligands
Organometallics, Vol. 26, No. 20, 2007 5043
Scheme 1
Scheme 2. Preparation of Amidophosphines 2-4 (HOBt )
1-hydroxybenzotriazole, EDC )
N-[3-(dimethylamino)propyl]-N′-ethylcarbodiimide)
the ligand structure.13 This initiated our interest in exploring
the catalytic potential of chiral phosphinoferrocene carboxam-
ides. Our interest was stimulated also by our previous work on
amides derived from 1′-(diphenylphosphino)ferrocenecarboxylic
acid (Hdpf) that have been used as synthetic precursors to
C-chiral phosphinoferrocene oxazolines14 and Fischer-type
P-chelated carbenes15 as well as versatile ligands for palladium
complexes and for Suzuki cross-coupling reaction.16
Scheme 3
With this contribution we report the preparation and catalytic
utilization in asymmetric allylic alkylation of phosphinofer-
rocene carboxamides derived from the achiral Hdpf and from
its planar chiral isomer, (Sp)-2-(diphenylphosphino)ferrocen-
ecarboxylic acid ((Sp)-1) and benzylic amines. We also present
the X-ray structural and solution NMR study of the best
performing ligand, (Sp)-2-(diphenylphosphino)-1-(N-benzylcar-
bamoyl)ferrocene ((Sp)-2), and the cationic complex [Pd(η3-1,3-
Ph2C3H3){(Sp)-2-η2:κP}]ClO4 ((Sp)-8), which can serve as a
model for the reaction intermediate.
spectra, those of (Sp)-2 and (R,Sp)-3/(S,Sp)-3 are observed as a
double triplet and double doublets, respectively. Coupling of
the amide proton with 31P in the case of the planar-chiral amides
1
2 and 3 was clearly established by 31P-decoupled H NMR
spectra, in which the amide signals collapse into a simple,
proton-coupled triplet for (Sp)-2 or doublets for the 1-phenylethyl
amides (R,Sp)-3 and (S,Sp)-3. The associated long-range 31P-
1H interaction is unexpectedly large (5JPH 13-14 Hz) and is
likely the consequence of through-bond spin-spin interactions
within the extended conjugated π-electron system involving the
phosphino-substituted cyclopentadienyl ring and the amide
moiety. Such an assumption is supported by the structure
determination for (Sp)-2 (see below), which reveals the P-C-
C-C-N atom set to be coplanar within ca. 0.15 Å, while the
amide NH group is oriented away from the phosphine group,
i.e., in a position unfavorable for a through-space (P‚‚‚HN)
interaction.
Catalytic Tests. Amido-phosphines 2-4 were employed as
ligands in palladium-catalyzed enantioselective allylic alkyla-
tion1 of racemic (E)-1,3-diphenylprop-2-en-1-yl acetate (5) with
dimethyl malonate to give dimethyl [(E)-1,3-diphenylprop-2-
en-1-yl]malonate (6 in Scheme 3). The model substrate 5 has
been chosen mainly because of the known reaction mechanism
and its symmetric nature and also due to a number of available
literature reports concerning this substrate that allow for a
comparison of the ligand efficiency. The reactions were carried
out in dichloromethane using 5 mol % of palladium catalysts
generated in situ from the appropriate ligand and di-µ-chlori-
dobis(η3-allyl)dipalladium(II), with dimethyl malonate-N,O-bis-
(trimethylsilyl)acetamide (BSA)/alkali metal acetate as the
nucleophile source.18 The results are summarized in Table 1.
At room temperature, the alkylation reaction in the presence
of acid (Sp)-1 and amides thereof proceeded with complete
Results and Discussion
Preparation of the Amido-phosphine Ligands. Compounds
2-4 have been obtained by reaction of the respective phosphi-
nocarboxylic acids with the appropriate amines (i.e., benzy-
lamine, (R)- and (S)-1-phenylethylamine) in the presence of
N-[3-(dimethylamino)propyl]-N′-ethylcarbodiimide and 1-hy-
droxybenzotriazole (Scheme 2).15,16c,17 The amides were isolated
by column chromatography as air-stable, orange solids and
characterized by conventional spectral methods and elemental
analysis. In addition, the crystal structure of (Sp)-2 has been
determined by single-crystal X-ray diffraction.
Compounds 2-4 show the typical amide bands in IR spectra
and molecular ions in their mass spectra. Their NMR spectra
display signals attributable to a PPh2-bearing, 1,2- (for 2 and
3) or 1,1′-disubstituted (for 4) ferrocene framework and the
amide substituents. Whereas the amide NH protons in (R)-4 and
1
(S)-4 give rise to the expected broad doublets in the H NMR
(13) Lamacˇ, M.; C´ısaˇrova´, I.; Sˇteˇpnicˇka, P. Eur. J. Inorg. Chem. 2007,
2274-2287.
(14) Drahonˇovsky´, D.; C´ısarˇova´, I.; Sˇteˇpnicˇka, P.; Dvorˇa´kova´, H.; Malonˇ,
P.; Dvorˇa´k, D. Collect. Czech. Chem. Commun. 2001, 66, 588-604.
(15) Meca, L.; Dvorˇa´k, D.; Ludv´ık, J.; C´ısaˇrova´, I.; Sˇteˇpnicˇka, P.
Organometallics 2004, 23, 2541-2551.
(16) (a) Sˇteˇpnicˇka, P.; Lamacˇ, M.; C´ısaˇrova´, I. Polyhedron 2004, 23,
921-928. (b) Sˇteˇpnicˇka, P.; Schulz, J.; C´ısaˇrova´, I.; Fejfarova´, K. Collect.
Czech. Chem. Commun. 2007, 72, 453-467. (c) Ku¨hnert, J.; Dusˇek, M.;
Demel, J.; Lang, H.; Sˇteˇpnicˇka, P. Dalton Trans. 2007, 2802-2811.
(17) Kraatz, H.-B. J. Inorg. Organomet. Polym. Mater. 2005, 15, 83-
106.
(18) (a) Trost, B. M.; Murphy, D. J. Organometallics 1985, 4, 1143-
1145. (b) El Gihani, M. T.; Heaney, H. Synthesis 1998, 357-375.

5044 Organometallics, Vol. 26, No. 20, 2007
Lamacˇ et al.
Table 1. Application of the Chiral Amides to
Palladium-Catalyzed Enantioselective Allylic Alkylationa
T
(°C)
time
(h)
conversion
(%)b
ee (%)
entry
ligand
additive
[config]c
1
2
3
4
5
6
7
8
(Sp)-1
(Sp)-2
(R,Sp)-3
(S,Sp)-3
(R)-4
22
22
22
22
22
22
22
22
22
0
20
20
20
20
20
20
20
20
20
42
20
20
20
KOAc
KOAc
KOAc
KOAc
KOAc
KOAc
none
LiOAc
NaOAc
NaOAc
KOAc
RbOAc
CsOAc
100 (91)
100 (91)
100 (97)
100 (95)
100 (90)
100 (92)
85
100
100
41
100
50 [R]
58 [R]
49 [R]
21 [R]
0
(S)-4
0
(Sp)-2
(Sp)-2
(Sp)-2
(Sp)-2
(Sp)-2
(Sp)-2
(Sp)-2
90 [R]
48 [R]
84 [R]
88 [R]
58 [R]
44 [R]
49 [R]
9
10
11
12
13
22
22
22
100
100
a The results are an average of two independent runs. For detailed
conditions, see Experimental Section. b Conversions were determined by
1H NMR spectroscopy. The isolated yield is given in parentheses. c Absolute
configuration has been assigned via comparison of the sign of the optical
rotation with the literature data.40
conversions within less than 20 h, yielding predominantly (R)-
6. Amide (Sp)-2 induced the highest enantioselectivity, followed
by the acid (entries 1-6 in Table 1). Introduction of the methyl
group onto the aliphatic carbon of the benzyl substituent reduced
the degree of asymmetric induction, the decrease being pro-
nounced much more for the S-configured phenylethyl group than
for its enantiomer. Somewhat unexpectedly, the 1,1′-ferrocene
derivatives 4 afforded only racemic 6. This markedly contrasts
with the previous successful applications of the structurally
related [1′-(diphenylphosphino)ferrocenyl]oxazolines.2e,19
The reaction conditions were subsequently optimized for
ligand (Sp)-2 by changing the base additive and the reaction
temperature (entries 2 and 7-13). Reaction performed without
a base proceeded with a slower rate but with the highest ee
(entry 7). Among the reactions performed in the presence of
alkali metal acetates (entries 2 and 8-13), the one with NaOAc
proceeded with the highest enantioselectivity. The enantiose-
lectivity further increased upon cooling to 0 °C, though on
account of the reaction rate (entries 9 and 10). The influence of
the acetate additive is difficult to rationalize since its solubility,
basicity, size of the counterion, and its ability to form ion pairs
with the formed carbanion may all influence the enantioselec-
tivity.20 Generally, the trends differ for individual catalytic
systems, even among the ferrocene donors. For instance, a
continuous rise in ee values with increasing size of the alkali
metal cation has been observed in alkylation of 5 in the presence
of Trost-type ligand II9a as well as in the alkylation of cyclohex-
2-enyl acetate in the presence of C2-symmetric ferrocene
diphosphine-disulfone.21 By contrast, catalysts based on [2-(thio-
alkyl)ferrocenyl]oxazolines showed only marginal variation in
ee’s upon changing the alkali metal cation.22
Figure 1. PLATON plot of the molecular structure of (Sp)-2.
Displacement ellipsoids are shown at the 30% probability level.
Only labels for the pivotal and their adjacent carbon atoms with
the consecutively numbered rings are shown.
Scheme 4
lization from a dichloromethane-diethyl ether mixture and
characterized by NMR, IR, and ESI-MS spectra and by
elemental analysis. Whereas the composition of the cation in
(Sp)-8 is clearly reflected in ESI-MS spectra, the O,P-bidentate
coordination of the ferrocene ligand can be inferred from a low-
field shift of the 31P NMR resonance (∆δP ca. +39 ppm) and
from a shift of the νCdO (amide I) band to lower energies (∆ν
) -36 cm-1). Finally, the presence of the perchlorate counterion
is manifested by its strong ν3 (composite 1054-1113 cm-1
)
and ν4 (623 cm-1) bands in the IR spectrum.
In solution, (Sp)-8 exists as a mixture of isomers differing
presumably by conformation of the allyl unit (syn/syn vs syn/
anti) and its orientation toward the ferrocene unit (exo/endo),
which is in line with observations made in similar systems.23
Two sets of signals in ca. 2.7:1 ratio could be detected in the
1H and 31P NMR spectra. The major isomer was assigned an
exo-syn-syn structure24 (shown in Scheme 4) on the basis of
Preparation of Complex (Sp)-8 and Structural Study.
Cationic (η3-allyl)palladium complex (Sp)-8 was obtained by
bridge cleavage of di-µ-chloridobis(η3-1,3-diphenylallyl)dipal-
ladium(II) (7) with the stoichiometric amount of (Sp)-2 in
dichloromethane followed by halide abstraction with silver(I)
perchlorate (Scheme 4). The complex was isolated by crystal-
(23) Selected examples of (η3-allyl)palladium complexes with bidentate
ferrocene ligands: (a) Pregosin, P. S.; Salzmann, R.; Togni, A. Organo-
metallics 1995, 14, 842-847. (b) Barbaro, P.; Pregosin, P. S.; Salzmann,
R.; Albinati, A.; Kunz, R. W. Organometallics 1995, 14, 5160-5170. (c)
Burckhardt, U.; Gramlich, V.; Hofmann, P.; Nesper, R.; Pregosin, P. S.;
Salzmann, R.; Togni, A. Organometallics 1996, 15, 3496-3503. (d)
Ferna´ndez-Gala´n, R.; Jalo´n, F. A.; Manzano, B. R.; Rod´ıguez-de la Fuente,
J.; Vrahami, M.; Jedlicka, B.; Weissensteiner, W.; Jogl, G. Organometallics
1997, 16, 3758-3768. (e) Go´mez-de la Torre, F.; Jalo´n, F. A.; Lo´pez-
Agenjo, A.; Manzano, B. R.; Rodr´ıguez, A.; Sturm, T.; Weissensteiner,
W.; Mart´ınez-Ripoll, M. Organometallics 1998, 17, 4634-4644. (f) Tu,
T.; Zhou, Y.-G.; Hou, X.-L.; Dai, L.-X.; Dong, X.-C.; Yu, Y.-H.; Sun, J.
Organometallics 2003, 22, 1255-1265. (g) Cho, C.-W.; Son, J.-H.; Ahn,
K. H. Tetrahedron: Asymmetry 2006, 17, 2240-2246.
(19) Sutcliffe, O. B.; Bryce, M. R. Tetrahedron: Asymmetry 2003, 14,
2297-2325 (review).
(20) (a) Trost, B. M.; Bunt, R. C. J. Am. Chem. Soc. 1998, 120, 70-79.
(b) Trost, B. M.; Bunt, R. C. J. Am. Chem. Soc. 1994, 116, 4089-4090.
(21) Raghunath, M.; Gao, W.; Zhang, X. Tetrahedron: Asymmetry 2005,
16, 3676-3681.
(22) You, S.-L.; Zhou, Y.-G.; Hou, X.-L.; Dai, L.-X. Chem. Commun.
1998, 2765-2766.

Chiral Phosphinoferrocene Carboxamide Ligands
Organometallics, Vol. 26, No. 20, 2007 5045
Table 2. Selected Geometric Parameters for (Sp)-2 and
(Sp)-8‚Me2CO (in Å and deg)
Coordination Geometry of (Sp)-8‚Me2CO
Pd-P
2.2863(6)
2.106(2)
2.133(3)
2.177(3)
2.237(3)
1.424(5)
1.389(5)
1.484(5)
1.466(5)
P-Pd-O
93.52(6)
106.34(9)
170.7(1)
93.2(1)
160.1(1)
66.9(1)
117.9(3)
123.7(3)
126.1(3)
Pd-O
P-Pd-C(31)
Pd-C(31)
Pd-C(32)
Pd-C(33)
C(31)-C(32)
C(32)-C(33)
C(31)-C(34)
C(32)-C(40)
P-Pd-C(33)
O-Pd-C(33)
O-Pd-C(31)
C(31)-Pd-C(33)
C(31)-C(32)-C(33)
C(32)-C(31)-C(34)
C(32)-C(33)-C(40)
Geometry of the Free and Coordinated Ligand
parameter (Sp)-2 (Sp)-8‚Me2CO
1.6407(8) 1.644(1)
Fe-Cg(1)
Fe-Cg(1)
1.6441(9)
2.9(1)
1.660(2)
4.9(2)
Cp(1),Cp(2)
P-C(2)
1.823(2)
1.837(2)
1.841(2)
1.475(2)
1.238(2)
1.350(2)
100.09(7)-102.77(8)
124.6(1)
128.6(1)
122.0(2)
123.4(1)
128.5(2)
0.4(2)
1.806(3)
1.824(3)
1.815(3)
1.483(4)
1.256(3)
1.256(3)
102.2(1)-105.7(1)
128.3(2)
124.8(2)
118.7(3)
126.9(3)
125.0(3)
-11.0(4)
0.8(5)
P-C(12)
P-C(18)
C-C(11)
C(11)-O
Figure 2. Section of the hydrogen-bonded assembly in the structure
of (Sp)-2 showing hydrogen bonds as dashed lines (only hydrogen-
bonded H atoms are shown). Symmetry operations: A: -x, y +
1/2, 1/2 - z; B: -x, y - 1/2, 1/2 - z. Selected parameters: N‚‚‚O
) 3.284(2) Å, angle at H(1N) ) 170°; C(5)‚‚‚O ) 3.150(2) Å,
angle at H(5) ) 151°.
C(11)-N
C-P-C
C(1)-C(2)-P
C(3)-C(2)-P
O-C(11)-N
C(2)-C(1)-C(11)
C(5)-C(1)-C(11)
P-C(2)-C(1)-C(11)
O-C(11)-N-C(24)
2.9(2)
a The ring planes are defined as follows: Cp(1) ) C(1-5), Cp(2) )
C(6-10); Cg(1,2) are the respective ring centroids.
2D NOESY spectra that showed correlations between the
terminal allyl hydrogens, thus indicating a W-shape for the allyl
moiety. Additionally, there is a cross-peak between the NH
resonance and the adjacent hydrogen at the disubstituted
ferrocene ring. NOE correlations between the allyl and phenyl
protons are of limited diagnostic value due to extensive overlaps
in the region of aromatic protons. Nevertheless, the cross-peaks
at δH 5.00 × ∼7.20, 5.98 × ∼7.70, and 6.61 × ∼7.20, ∼7.70
support the mentioned conformation, where the terminal protons
at the W-configured allyl group are directed toward different
phenyl protons, while the meso CH in between correlates with
both aromatic moieties. Although there is no such direct
information about the minor isomer, it can tentatively be
assigned the endo-syn-syn (or M-shaped) conformation, when
considering the similarity of the chemical shifts and, particularly,
the JHH and JPH coupling constants.
The solid-state structures of solvate (Sp)-8‚Me2CO and ligand
(Sp)-2 have been determined by single-crystal X-ray diffraction.
The molecular structure of (Sp)-2 is shown in Figure 1, and
selected geometric data are collected in Table 2. The ferrocene
unit in (Sp)-2 has a regular geometry, showing a tilt of only
2.9(1)° and almost identical Fe-ring centroid distances. Like-
wise, the geometry of the amide group does not differ much
from that in other structurally characterized secondary ferrocene
carboxamides.25 The amide plane is oriented so that the oxygen
atom points toward the phosphine moiety and is rotated by 16.0-
(2)° from the Cp(1) plane (see Table 2 for definitions). The
benzyl group is located above the ferrocene unit and together
with one of the PPh2 phenyl rings pointing in the same direction,
C(12-17), which is almost perpendicular to the benzylic
phenyl ring [dihedral angle ) 83.0(1)°], shield the donor atoms
from above the ferrocene moiety. In the crystal, the individual
Figure 3. PLATON plot of the cation in the structure of (Sp)-
8‚Me2CO. Displacement ellipsoids correspond to 30% probability.
The ring atoms are numbered consecutively and, hence, the labels
of only the pivotal and their adjacent carbon atoms are shown to
avoid complicating the figure.
molecules of (Sp)-2 associate into infinite linear chains
along the crystallographic 21 screw axes via cooperative
N-H(1N)‚‚‚O and C(5)-H(5)‚‚‚O hydrogen bonds (Figure 2).
Crystals of solvate (Sp)-8‚Me2CO were obtained by recrys-
tallization from acetone-diethyl ether.26 The structure of the
cation in (Sp)-8‚Me2CO is depicted in Figure 3, and selected
(25) FcC(O)NHCH2R: (a) R ) Ph: Hursthouse, M. B.; Coles, S. J.;
Tucker, J. H. R. Private communication to CCDC (refcode BATLEO). (b)
R ) CH2OH: Sˇteˇpnicˇka, P.; C´ısaˇrova´, I. CrystEngComm 2005, 7, 37-43.
(c) R ) CtCH: Brosch, O.; Weyhermueller, T.; Metzler-Nolte, N. Eur. J.
Inorg. Chem. 2000, 323-330. (d) R ) Et: Oberhoff, M.; Duda, L.; Karl,
J.; Mohr, R.; Erker, G.; Froehlich, R.; Grehl, M. Organometallics 1996,
15, 4005-4011.
(24) Conformers are denoted exo (endo) when the meso-CH group of
the allyl moiety is directed away from (toward) the ferrocene unit.

5046 Organometallics, Vol. 26, No. 20, 2007
Lamacˇ et al.
Scheme 5. (a) Idealized Depiction of the Plausible Reaction Intermediates VI and VII (Y ) CO2Me); (b,c) Space-Filling Model
of the Cation in (Sp)-8 as Viewed (b) along the C(33)-C(31) Line (i.e., from the benzyl group) and (c) Perpendicular to the
η3-Allyl Moiety
geometric parameters are given in Table 2. The allyl moiety
adopts an exo-syn-syn arrangement, which is in line with the
solution NMR data of the major isomer (see above). The
dihedral angle of the allyl plane, C(31-33), and the plane
defined by Pd and its two remaining ligating atoms (P,O) is
65.9(3)°, the meso carbon atom C(32) being most distant from
the ferrocene axis. The Pd-C(allyl) distances increase gradually
along the allyl moiety from C(31) to C(33), with the extreme
values differing by as much as 0.10 Å. Nonetheless, this
observation is in accordance with a stronger trans-influence27
of the P-donor. Desymmetrization of the 1,3-diphenylallyl
moiety is manifested also by the “interligand” angles involving
the terminal allyl carbon atoms P-Pd-C(31) and O-Pd-C(33),
which differ by about 13°.
inappropriate, as these structures represent the only three
structurally characterized [Pd(η3-1,3-Ph2C3H3)(L-L′-κ2O,P)]+
cations.30
The ferrocene Cp(1) and [PdPO] planes in (Sp)-8‚Me2CO are
nearly coplanar (the dihedral angle is only 3.4(1)°). When
compared with the structure of the free ligand, the coordination
leads to an elongation of the C(11)dO and C(1)-C(11) bonds
by 0.018 and 0.026 Å, respectively, while the C(11)-N bond
shrinks by 0.025 Å. A slight opening of the C(1)-C(11)-O
angle (2.6°) is also observed and is compensated by a closure
of the O-C(11)-N angle (3.3°). The amide plane in the
complex is rotated from the Cp(1) plane by 8.7(3)°. Furthermore,
the coordination brings about conformational changes that
clearly aid the accommodation of the bulky (η3-diphenylallyl)-
Pd moiety into the chiral donor pocket. First, the PPh2 moiety
is rotated along the pivotal C(2)-P bond below the Cp(1) plane.
Second, the amide benzyl substituent is moved below the Cp-
(1) ring as if mirrored through the Cp(1) plane (cf. the torsion
angles N-C(24)-C(25)-C(26) ) -146.7(2)°/145.5(4)° and
N-C(24)-C(25)-C(26) ) 34.0(2)°/-40.5(5)° in (Sp)-2/(Sp)-
8‚Me2CO).
Mechanistic Considerations. Because the symmetric allyl
precursor 5 eliminates a possible bias due to unlike allyl
substituents, the enantioselectivity is dictated predominantly by
the steric and electronic properties of the coordinated chiral
ligand. As discussed above, the collected structural data suggest
the exo-syn-syn isomer of (Sp)-8 (VIa in Scheme 5) to be the
preferred species both in solution and in the solid state. In view
of the fundamental mechanistic study by Bosnich et al.,31 this
intermediate should be the precursor to the major product.
Indeed, VIa gives rise to (R)-6 provided that the nucleophile
attacks preferentially at the allyl terminus located trans to
phosphorus as the donor with the stronger trans-influence.32
The preference of exo-syn-syn allyl intermediate (VIa) over
The Pd-X (X ) C, O, P) distances observed for (Sp)-8‚Me2-
CO compare favorably with those reported for (η3-1,3-diphe-
nylallyl)palladium complexes bearing (S)-2-(diphenylphosphino)-
2′-(diphenylphosphoryl)-1,1′-binaphthyl7,28 and (1R,2R)-1-{2-
(diphenylphosphino)benzoylamino}-2-{2-(diphenyl-
amino)benzoylamino}cyclohexane4,29 as the P,O-chelating ligands.
The ligand bite angle P-Pd-O in (Sp)-8‚Me2CO of 93.52(5)°
fits in between those of the reference compounds (98.5(2)° and
89.2(4)°, respectively). It is noteworthy that the bite angles
correlate with the degree of asymmetric induction, the ligand
with the lowest bite angle showing the highest ee under similar
reaction conditions. Yet, any general conclusions would be
(26) Crystallization from chloroform-diethyl ether afforded the solvate
(Sp)-8‚CHCl3. The crystal structures of (Sp)-8‚Me2CO and (Sp)-8‚CHCl3 are
practically identical, differing only by the solvent molecules located in
structural voids among the bulky complex molecules. Crystallographic data
for (Sp)-8‚CHCl3: orthorhombic, space group P212121 (no. 19), a ) 9.5456-
(2) Å, b ) 15.8592(5) Å, c ) 28.4547(9) Å; V ) 4307.6(2) Å3, Z ) 4 at
150 K.
(27) (a) Appleton, T. G.; Clark, H. C.; Manzer L. E. Coord. Chem. ReV.
1973, 10, 335-422. (b) Hartley, F. R. The Chemistry of Platinum and
Palladium; Applied Science: London, 1973; pp 299-303.
(28) Selected data: Pd-O 2.101(6) Å, Pd-P 2.321(2), Pd-C(allyl trans-
P) 2.253(7), Pd-C(allyl meso) 2.139(8), and Pd-C(allyl trans-O) 2.113-
(9) Å at 293 K.
(29) Selected data: Pd-O 2.13(1) Å, Pd-P 2.286(6), Pd-C(allyl trans-
P) 2.20(3), Pd-C(allyl meso) 2.10(2), and Pd-C(allyl trans-O) 2.07(2) Å
at 213 K.
(30) Cambridge Structural Database, version 5.28 (November 2006) with
updates of January and May 2007.
(31) Bosnich et al. have shown that the major allylic intermediate gives
rise to the major product enantiomer: Mackenzie, P. B.; Whelan, J.; Bosnich,
B. J. Am. Chem. Soc. 1985, 107, 2046-2054.
(32) Theoretical calculations: (a) Bloechl, P.; Togni, A. Organometallics
1996, 15, 4125-4132. (b) Ward, T. R. Organometallics 1996, 15, 2836-
2838.

Chiral Phosphinoferrocene Carboxamide Ligands
Organometallics, Vol. 26, No. 20, 2007 5047
NMR spectra were measured on a Varian Unity Inova 400
the endo-syn-syn form (VIb) as the most probable other
component can be accounted for by steric reasons. The
crystallographic data (Scheme 5) indicate the diphenylallyl
moiety in VIa to better avoid sterically congested space. Besides,
both VIa and the η2-alkene species VIIa resulting by addition
of the nucleophile and rotation of the formed alkene retain better
the possibility of stabilization via π-π interactions of the
aromatic rings than the intermediates occurring along the
pathway involving the endo-syn-syn isomer (VIb f VIIb). It
should be noted, however, that this explanation represents a
summary of the available data, neglecting a possible structural
reorganization of the ligand and individual reaction rates of the
isomeric intermediates.
1
spectrometer at 25 °C. H{31P} NMR spectra were recorded on a
Bruker Avance DRX 500 spectrometer. Chemical shifts (δ/ppm)
1
are given relative to internal SiMe4 (13C and H) or to external
85% aqueous H3PO4 (31P). The assignment of the NMR signals is
based on COSY, 13C gHSQC, and 13C gHMBC spectra. IR spectra
were recorded on an FT IR Nicolet Magna 650 spectrometer.
Positive ion electron impact (EI) and fast atom bombardment (FAB)
mass spectra (including high-resolution (HR) measurements) were
obtained with a ZAB SEQ spectrometer. Electrospray (ESI) mass
spectra were recorded on a Bruker Esquire 3000 spectrometer for
methanol solutions. Optical rotations were determined with an
Autopol III automatic polarimeter (Rudolph Research) at room
temperature.
Introduction of a methyl group at the benzylic R-carbon
destabilizes all intermediates whose phenyl group attached to
the allylic terminus trans to the phosphorus is oriented upward
with respect to the ferrocene unit, including the exo-syn-syn
isomer. This holds particularly true for (S,Sp)-4, where the
methyl groups point into the donor pocket. Accordingly, (S,Sp)-4
shows the lowest ee among the donors derived from (Sp)-1
(Table 1). A similar observation was made with C-chiral amides
(R)- and (S)-(2-Ph2PC6H4)C(O)NHCH(Me)Ph.5c It is also worth
noting that the dominating role of planar chirality in amides
obtained from (Sp)-1 contrasts with the conclusions presented
for the structurally related [2-(diphenylphosphino)ferrocenyl]-
oxazolines, where the central chirality has been recognized as
the main stereodiscriminating factor.2e,19,33
Safety Note. CAUTION! Although we have not encountered
any problems, it should be noted that perchlorate salts of metal
complexes with organic ligands are potentially explosive and should
be handled only in small quantities and with great care.
General Procedure for the Preparation of the Amides.
1-Hydroxybenzotriazole (HOBt) and the respective acid were
suspended in dichloromethane (15 mL), and the reaction mixture
was stirred at 0 °C for 5 min. Then, N-[3-(dimethylamino)propyl]-
N′-ethylcarbodiimide (EDC) was slowly added, and the formed
solution was stirred at 0 °C for 30 min. Finally, the appropriate
amine was introduced (diluted with a small amount of dichlo-
romethane), and stirring was continued at room temperature for
another 20 h. The mixture was extracted with 3 M HCl (10 mL),
a saturated aqueous NaHCO3 solution (2 × 10 mL), and brine (10
mL). The organic phase was separated, dried over MgSO4, and
evaporated under vacuum, leaving an orange residue, which was
purified by column chromatography on silica gel using a dichlo-
romethane-methanol mixture (20:1) as the eluent.
Conclusions
In summary, amides derived from planar-chiral acid (Sp)-1
are efficient ligands for palladium-catalyzed, enantioselective
allylic alkylation of 1,3-diphenylallyl acetate, producing the
alkylated product preferably as the R-isomer. Their catalytic
efficiency is much better than that achieved with analogous
compounds derived from acid V13 and similar to donors I8,34
and IV.11 The collected catalytic results indicate that the course
of the catalyzed reaction is determined largely by the planar
chirality. However, the N-substituents can be used to tune the
catalyst properties through changing steric properties of the
chiral pocket.
(Sp)-2-(Diphenylphosphino)-1-(N-benzylcarbamoyl)fer-
rocene [(Sp)-2]. Starting with acid (Sp)-1 (104 mg, 0.25 mmol),
HOBt (38 mg, 0.28 mmol), EDC (0.05 mL, 0.3 mmol), and
benzylamine (29 mg, 0.27 mmol), the general procedure gave amide
1
(Sp)-2 as an orange, solid foam. Yield: 91 mg (72%). H NMR
(CDCl3): δ 3.80 (m, 1 H, C5H3), 4.07 (s, 5 H, C5H5), 4.46 (m, 1
H, C5H3), 4.54 (d, 3JHH ) 5.5 Hz, 2 H, CH2), 5.19 (m, 1 H, C5H3),
7.10-7.53 (m, 15 H, 3 × Ph), 7.70 (br dt, JPH ≈ 13 Hz, JHH ≈ 6
Hz, 1 H, NH). 13C{1H} NMR (CDCl3): δ 43.58 (CH2), 70.73
(C5H5), 71.49 (C5H3 CH), 73.76 (d, JPC ) 2 Hz, C5H3 CH), 74.41
(d, JPC ) 4 Hz, C5H3 CH), 74.98 (d, 2JPC ) 9 Hz, C5H3 C-CONH),
1
80.70 (d, JPC ) 19 Hz, C5H3 C-PPh2), 127.06, 127.49 (2 × Ph
Experimental Section
CH); 128.3-128.6 (m, 4 × PPh2 and Ph CH), 129.72 (PPh2 and
Ph CH), 132.13 (d, JPC ) 18 Hz, PPh2 CH), 135.06 (d, JPC ) 21
Hz, PPh2 CH), 135.76 (d, 1JPC ) 6 Hz, PPh2 Cipso), 137.68 (d, 1JPC
Materials and Methods. The syntheses were performed under
argon atmosphere with exclusion of direct daylight. Dichlo-
romethane was dried by standing over anhydrous potassium
carbonate and then distilled from calcium hydride. Hdpf,35 (Sp)-
1,36 1,3-diphenylallyl acetate (5),37 and di-µ-chloridobis(η3-1,3-
diphenylallyl)dipalladium(II) (7)38 were prepared following the
literature procedures. Other chemicals (Lachema, Fluka) and
solvents used for crystallizations and chromatography (Lach-Ner)
were used without further purification.
3
) 6 Hz, PPh2 Cipso), 138.69 (Ph Cipso), 170.20 (d, JPC ) 3 Hz,
CONH). 31P{1H} NMR (CDCl3): δ -20.4 (s). IR (Nujol): ν˜/cm-1
3362 (m, N-H), 1628 (vs, amide I), 1530 (vs, amide II), 1285
(m), 1179 (m), 1105 (m), 1002 (m), 936 (m), 843 (m), 823 (m),
748 (vs), 694 (vs), 499 (s), 481 (s). EI-MS: m/z (relative abundance)
503 (100, M+•), 438 (90, [M - C5H5]+), 412 (40, [M - CH2Ph]+),
346 (25, [412 - C5H6]+), 302 (14, [M - Ph2PO]+), 256 (7), 222
(8), 201 (90, [Ph2PO]+), 183 (10), 170 (11), 129 (10), 111 (11), 97
(19), 91 (19, [C7H7]+), 83 (22), 69 (32), 57 (39), 43 (34). HR-MS:
calcd for C30H26NOP56Fe (M+•) 503.1101, found 503.1120. [R]D
) -236.5 (c 1.0, CHCl3).
(33) You, S.-L.; Hou, X.-L.; Dai, L.-X.; Yu, Y.-H.; Xia, W. J. Org. Chem.
2002, 67, 4684-4695.
(34) It is worth noting that I-based catalysts produce preferably (R)-6
under similar conditions.
(35) Podlaha, J.; Sˇteˇpnicˇka, P.; C´ısaˇrova´, I.; Ludv´ık, J. Organometallics
(R,Sp)-2-(Diphenylphosphino)-1-[N-(1-phenylethyl)carbamoyl]-
ferrocene [(R,Sp)-3]. Starting with (Sp)-1 (104 mg, 0.25 mmol),
HOBt (38 mg, 0.28 mmol), EDC (0.05 mL, 0.3 mmol), and (R)-
(1-phenylethyl)amine (33 mg, 0.27 mmol), the above procedure
gave amide (R,Sp)-3 as an orange, solid foam. Yield: 97 mg (75%).
1996, 15, 543-550.
(36) Sˇteˇpnicˇka, P. New J. Chem. 2002, 26, 567-575.
(37) Acetate 5 was prepared by acetylation of 1,3-diphenylallyl alcohol,
which results from reduction of chalcone: (a) Kohler, E. P.; Chadwell, H.
M. Organic Syntheses; Wiley: New York, 1941; Collect. Vol. I, pp 78-
80. (b) Leung, W.; Cosway, S.; Jonmes, R. H. V.; McCann, H.; Wills, M.
J. Chem. Soc., Perkin Trans. 1 2001, 2588-2594. (c) Watson, I. D. G.;
Styler, S. A.; Yudin, A. K. J. Am. Chem. Soc. 2004, 126, 5086-5087.
(38) Hayashi, T.; Yamamoto, A.; Ito, Y.; Nishioka, E.; Miura, H.; Yanagi,
K. J. Am. Chem. Soc. 1989, 111, 6301-6311.
3
1H NMR (CDCl3): δ 1.58 (d, JHH ) 6.9 Hz, 3 H, CHCH3), 3.74
(m, 1 H, C5H3), 4.15 (s, 5 H, C5H5), 4.44 (m, 1 H, C5H3), 5.17 (m,
1 H, C5H3), 5.20 (m, 1 H, CHCH3), 6.98-7.56 (m, 15 H, 3 × Ph),
7.62 (dd, J ) 7.9 Hz, J ) 13.0 Hz, 1 H, CONH). 13C{1H} NMR

5048 Organometallics, Vol. 26, No. 20, 2007
Lamacˇ et al.
(CDCl3): δ 22.74 (CHCH3), 48.98 (CHCH3), 70.84 (C5H5), 71.28
(C5H3 CH), 73.96 (d, JPC ) 3 Hz, C5H3 CH), 74.40 (d, JPC ) 3
Hz, C5H3 CH), 74.91 (d, 2JPC ) 9 Hz, C5H3 C-CONH), 80.70 (d,
1JPC ) 18.9 Hz, C5H3 C-PPh2), 125.88, 126.69 (2 × Ph CH);
128.2-128.6 (m, 4 × PPh2 and Ph CH), 129.68 (PPh2 and Ph CH),
132.38 (d, JPC ) 17 Hz, PPh2 CH), 134.99 (d, JPC ) 20 Hz, PPh2
CH), 135.55 (d, 1JPC ) 7 Hz, PPh2 Cipso), 137.39 (d, 1JPC ) 6 Hz,
452 (m). EI-MS: m/z (relative abundance) 518 (9), 517 (26, M+•),
413 (20), 412 (72, [M - PhCHMe]+), 322 (12), 321 (48), 316 (18,
[M - 201]+), 226 (8), 202 (15), 201 (100, [Ph2PO]+), 197 (9),
183 (8), 171 (15), 170 (11), 141 (6), 121 (6, [FeC5H5]+), 105 (24),
79 (8), 77 (8), 56 (12, Fe+). HR-MS: calcd for C31H2856FeNOP
(M+•) 517.1258, found 517.1237. [R]D ) +48 (c 1.0, CHCl3).
(S)-1′-(Diphenylphosphino)-1-[N-(1-phenylethyl)carbamoyl]-
ferrocene [(S)-4]. Following the general procedure with Hdpf (415
mg, 1.0 mmol), HOBt (161 mg, 1.2 mmol), EDC (0.22 mL, 1.25
mmol), and (S)-(1-phenylethyl)amine (133 mg, 1.1 mmol) gave
amide (S)-4 as an orange solid. Yield: 465 mg (90%). The
spectroscopic data are identical with those of the R-isomer, [R]D
) -47 (c 1.0, CHCl3).
3
PPh2 Cipso), 143.33 (Ph Cipso), 169.21 (d, JPC ) 3 Hz, CONH).
31P{1H} NMR (CDCl3): δ -20.4 (s). IR (Nujol): ν˜/cm-1 3311
(br m, N-H), 1629 (s composite, amide I), 1528 (s, amide II),
1278 (w), 1260 (m), 1211 (w), 1107 (w), 1002 (w), 837 (w), 749
(vs composite), 700 (vs), 498 (s), 487 (s). EI-MS: m/z (relative
abundance) 517 (100, M+•), 452 (66, [M - C5H5]+), 412 (57, [M
- PhCHMe]+), 346 (21, [412 - C5H6]+), 316 (15, [M - Ph2PO]+),
222 (5), 201 (53, [Ph2PO]+), 183 (5), 170 (5), 121 (6), 105 (12,
[PhCHMe]+), 56 (5). HR-MS: calcd for C31H28NOP56Fe (M+•)
517.1258, found 517.1242. [R]D ) -208.5 (c 1.0, CHCl3).
Asymmetric Allylic Alkylation: General Procedure.39,14 Ligand
(25 µmol), [{Pd(η3-C3H5)Cl}2] (4.8 mg, 13 µmol), and base (0.05
mmol) were mixed with dry dichloromethane (3 mL), and the
mixture was stirred at room temperature for 30 min. Then, rac-
1,3-diphenylprop-2-en-1-yl acetate (5; 126 mg, 0.5 mmol) was
introduced followed, after stirring for another 5 min, by N,O-bis-
(trimethylsilyl)acetamide (BSA; 0.37 mL, 1.5 mmol) and dimethyl
malonate (0.17 mL, 1.5 mmol). The reaction mixture was stirred
at the reaction temperature for 20 h. Then, it was washed with a
saturated aqueous NH4Cl solution (2 × 5 mL), and the organic
layer was separated, dried over MgSO4, and concentrated in Vacuo.
Subsequent purification by column chromatography (silica gel;
hexane-ethyl acetate, 3:1) afforded the alkylation product. Opti-
mization of the reaction conditions (Table 2) was performed at half
scale.
(S,Sp)-2-(Diphenylphosphino)-1-[N-(1-phenylethyl)carbamoyl]-
ferrocene [(S,Sp)-3]. Starting with (Sp)-1 (104 mg, 0.25 mmol),
HOBt (38 mg, 0.28 mmol), EDC (0.05 mL, 0.3 mmol), and (S)-
(1-phenylethyl)amine (33 mg, 0.27 mmol), the general procedure
afforded amide (S,Sp)-3 as an orange, gummy material. Yield: 102
1
3
mg (79%). H NMR (CDCl3): δ 1.31 (d, JHH ) 7.0 Hz, 3 H,
CH3), 3.77 (m, 1 H, C5H3), 3.98 (s, 5 H, C5H5), 4.43 (apparent t,
J ≈ 2.7 Hz, 1 H, C5H3), 5.15 (m, 1 H, CHCH3), 5.16 (m, 1 H,
C5H3), 7.18-7.58 (m, 15 H, 3 × Ph), 7.77 (dd, J ) 8.2 Hz, J )
14.3 Hz, 1 H, CONH). 13C{1H} NMR (CDCl3): δ 21.90 (CHCH3),
49.21 (CHCH3), 70.66 (C5H5), 71.39 (C5H3 CH), 73.90 (d, JPC
)
1
2
Enantiomeric excesses were determined from H NMR spectra
3 Hz, C5H3 CH), 74.43 (d, JPC ) 3 Hz, C5H3 CH), 74.81 (d, JPC
) 9 Hz, C5H3 C-CONH), 80.75 (d, 1JPC ) 19 Hz, C5H3 C-PPh2),
126.24, 127.16 (2 × Ph CH); 128.3-128.7 (m, 4 × PPh2 and Ph
CH), 129.75 (PPh2 and Ph CH), 132.25 (d, JPC ) 18 Hz, PPh2
recorded in C6D6 in the presence of chiral lanthanide shift reagent
tris(3-trifluoroacetyl-d-camphorato)europium(III), Eu(facam)3, while
the configuration of the major component was assigned on the basis
of optical rotation of the mixture.40
1
CH), 135.0 (d, JPC ) 20 Hz, PPh2 CH), 135.53 (d, JPC ) 6 Hz,
Preparation of (η3-1,3-Diphenylallyl)[(Sp)-2-(diphenylphos-
phino)-1-(N-benzylcarbamoyl)ferrocene-κ2O,P]palladium(II) Per-
chlorate [(Sp)-8]. A suspension of (Sp)-2 (21 mg, 0.04 mmol) and
7 (13.4 mg, 0.02 mmol) in dichloromethane (3 mL) was stirred at
room temperature for 15 min to give a clear orange solution. Then,
silver perchlorate (8.5 mg, 0.04 mmol) was added, causing
immediate formation of a white precipitate (AgCl). After stirring
for 1 h, the precipitate was filtered off (PTFE syringe filter, 45 µm
pore size) and the yellow-orange filtrate was layered with diethyl
ether and allowed to crystallize at 4 °C for several days. The orange
crystalline product was isolated by suction and dried in Vacuo.
Yield: 27 mg (75%). Anal. Calcd for C45H39ClFeNO5PPd‚1.8CH2-
Cl2: C 53.26, H 4.07, N 1.33. Found: C 53.32, H 3.77, N 1.30.
ESI+: m/z 802 ([Pd(2)(Ph2C3H3)]+); the observed isotopic distribu-
tion fits the calculated one. (In the MS/MS spectrum, the ion at
m/z 802 fragments to give ions m/z 609, corresponding to [Pd-
(2)]+.) IR (Nujol): ν˜/cm-1 1592 (vs, CdO), 1553 (s), 1281 (m),
1208 (w), 1167 (m), 1113 (br vs, ClO4), 1067 (vs, ClO4), 1054 (s,
ClO4), 1026 (m), 1010 (w), 916 (m), 840 (m), 821 (m), 755 (s),
695 (s), 688 (s), 623 (s, ClO4), 548 (s), 523 (s), 513 (s), 490 (m),
465 (s), 456 (s).
PPh2 Cipso), 137.42 (d, 1JPC ) 6 Hz, PPh2 Cipso), 144.30 (Ph Cipso),
169.21 (d, 3JPC ) 3 Hz, CONH). 31P{1H} NMR (CDCl3): δ -20.1
(s). IR (RAS): ν˜/cm-1 3304 (br m, N-H), 1644 (vs, amide I),
1522 (s, amide II), 1310 (w), 1261 (m), 1211 (w), 1183 (w), 1157
(m), 1106 (m), 1093 (m), 1028 (w), 1002 (m), 821 (m), 744 (s),
697 (vs), 482 (m). EI-MS: m/z (relative abundance) 517 (100, M+•),
452 (66, [M - C5H5]+), 412 (57, [M - PhCHMe]+), 346 (21, [412
- C5H6]+), 316 (15, [M - Ph2PO]+), 222 (5), 201 (53, [Ph2PO]+),
183 (5), 170 (5), 121 (6), 105 (12, [PhCHMe]+), 56 (5). HR-MS:
calcd for C31H28NOP56Fe (M+•) 517.1258, found 517.1264. [R]D
) -179 (c 1.0, CHCl3).
(R)-1′-(Diphenylphosphino)-1-[N-(1-phenylethyl)carbamoyl]-
ferrocene [(R)-4]. Following the general procedure with Hdpf (415
mg, 1.0 mmol), HOBt (161 mg, 1.2 mmol), EDC (0.22 mL, 1.25
mmol), and (R)-(1-phenylethyl)amine (133 mg, 1.1 mmol) gave
1
amide (R)-4 as an orange solid. Yield: 486 mg (94%). H NMR
(CDCl3): δ 1.56 (d, 3JHH ) 6.9 Hz, 3 H, CHMe), 3.92, 4.00 (2 ×
m, 1 H, C5H4); 4.19 (apparent t, 3JHH ) 1.9 Hz, 2 H, C5H4), 4.31,
4.34 (2 × dt, J ≈ 1.3, 2.5 Hz, 1 H, C5H4); 4.54-4.59 (m, 2 H,
3
C5H4); 5.25 (virtual p, J ≈ 7.1 Hz, 1 H, CHMe), 6.17 (br d, JHH
) 8.1 Hz, 1 H, NH), 7.18-7.42 (m, 15 H, Ph). 13C{1H} NMR
(CDCl3): δ 21.87 (CHMe), 48.75 (CHMe), 69.60 (d, JPC ) 2 Hz,
C5H4 CH), 69.73 (d, JPC ) 1 Hz, C5H4 CH), 71.46 (2C, C5H4 CH),
72.64 (d, JPC ) 4 Hz, C5H4 CH), 72.78 (d, JPC ) 3 Hz, C5H4 CH),
74.14 (d, JPC ) 5 Hz, C5H4 CH), 74.27 (d, JPC ) 4 Hz, C5H4 CH),
126.38 (2C, Ph CH), 127.28 (Ph CH), 128.27 (d, JPC ) 7 Hz, PPh2
CH), 128.28 (d, JPC ) 7 Hz, PPh2 CH), 128.59 (PPh2 CH), 128.75,
128.80 (2 × Ph CH); 133.35 (d, JPC ) 19 Hz, PPh2 CH), 133.45
Solution NMR spectra show the presence of two isomers in ca.
2.7:1 ratio. NMR data for the major isomer (exo-syn-syn). 1H NMR
(CDCl3): δ 3.91, 3.97 (2 × dd, 2JHH ) 14.3 Hz, 3JHH ) 6.4 Hz, 1
H, NHCH2Ph), 3.97 (m, 1 H, C5H3), 4.17 (s, 5 H, C5H5), 4.66
(apparent t, J ) 2.7 Hz, 1 H, C5H3), 5.00 (d, 3JHH ) 10.7 Hz, 1 H,
allyl CH trans-O), 5.58 (m, 1 H, C5H3), 5.98 (dd, 3JHH ) 13.3 Hz,
3
3JPH ) 8.4 Hz, 1 H, allyl CH trans-P), 6.61 (dd, JHH ) 13.3 Hz,
3JHH ) 10.9 Hz, 1 H, allyl CH meso), 6.12 and 6.86-7.76 (m, 25
1
(d, JPC ) 20 Hz, PPh2 CH), 138.04, 138.20 (2 × d, JPC ) 9 Hz,
3
H, 5 × Ph), 8.36 (t, JHH ) 6.7 Hz, 1 H, NH). 31P{1H} NMR
PPh2 Cipso); 143.56 (Ph Cipso), 168.91 (CO); the signal due to C5H4
C-CONH was not found due to overlaps. 31P{1H} NMR
(CDCl3): δ -16.9 (s). IR (Nujol): ν˜/cm-1 1625 (vs, amide I), 1527
(vs, amide II), 1307 (m), 1275 (m), 1209 (w), 1175 (w), 1160 (m),
1092 (w), 1026 (s), 832 (m), 820 (m), 741 (vs), 697 (vs), 493 (s),
(39) (a) Zang, W.; Yoneda, Y.; Kida, T.; Nakatsuji, Y.; Ikeda, I.
Tetrahedron: Asymmetry 1998, 9, 3371-3380.
(40) Hayashi, T.; Yamamoto, A.; Hagihara, T.; Ito, Y. Tetrahedron Lett.
1986, 27, 191-194.

Chiral Phosphinoferrocene Carboxamide Ligands
Organometallics, Vol. 26, No. 20, 2007 5049
Table 3. Crystallographic Data, Data Collection, and
Structure Refinement Parameters for (Sp)-2 and
(Sp)-8‚Me2CO
chromatized Mo KR radiation (λ ) 0.71073 Å) and analyzed with
the HKL program package.41 The data for (Sp)-8‚Me2CO were
corrected for absorption by using a Gaussian method. The range
of transmission factors is given in Table 3.
(Sp)-2
(Sp)-8‚Me2CO
The structures were solved by direct methods (SIR9742) and
refined by full-matrix least-squares on F2 (SHELXL9743). The non-
hydrogen atoms were refined with anisotropic displacement pa-
rameters. The amide hydrogen atom [H(1N)] in (Sp)-2 and (Sp)-
8‚Me2CO as well as the allylic hydrogens [H(31), H(32), and H(33)]
in (Sp)-8‚Me2CO were located on the electron density maps and
refined as riding atoms. All other hydrogen atoms were included
in the calculated positions and refined as riding atoms with Uiso-
(H) assigned to a multiple of Ueq of their bonding atom. Selected
crystallographic data are given in Table 3. Geometric parameters
and structural drawings were obtained by using a recent version of
Platon program.44 The calculated numerical values are rounded with
respect to their estimated standard deviations (esd’s) given with
one decimal; parameters involving hydrogen atoms in calculated
positions are given without esd’s.
formula
C30H26FeNOP
503.34
orthorhombic
P212121 (no. 19)
150(2)
9.8424(1)
10.6075(1)
23.6117(4)
2465.14(5)
4
1.356
0.700
e
32 793
5637/5298
C48H45ClFeNO6PPdf
960.52
orthorhombic
P212121 (no. 19)
150(2)
9.4409(1)
15.8585(2)
28.5158(3)
4269.34(8)
4
M (g mol-1
cryst syst
)
space group
T (K)
a (Å)
b (Å)
c (Å)
V (Å3)
Z
D
calc (g mL-1
)
1.494
0.912
0.673-0.860
52 778
µ(Mo KR) (mm-1
)
Ta
total no. of diffractions
no. of unique/obsdc
diffractions
9761/8985
R
int (%)b
4.8
2.68
3.11, 6.11
-0.00(1)
0.18, -0.32
649277
6.25
3.30
3.90, 8.09
-0.01(2)
0.65, -0.47
649278
R (obsd data) (%)c,d
R, Rw (all data) (%)d
Flack’s parameter
Full crystallographic data have been deposited with the Cam-
bridge Crystallographic Data Centre and can be obtained free from
http://www.ccdc.cam.ac.uk/conts/retrieving.html. The deposition
numbers are quoted in Table 3.
∆F (e Å-3
)
CCDC entry
b
2
2
a The range of transmission coefficients. Rint ) ∑|Fo - Fo (mean)|/
2
2
Acknowledgment. This work is a part of the long-term
research projects supported by the Ministry of Education, Youth
and Sports of the Czech Republic (project nos. MSM0021620857
and LC06070). Ing. H. Dvoˇra´kova´ and I. Bartosˇova´ are thanked
∑Fo , where Fo (mean) is the average intensity of symmetry-equivalent
diffractions. c Diffractions with Io > 2σ(Io). d R ) ∑||Fo| - |Fc||/∑|Fo|, Rw
)[∑{w(Fo2-Fc2)2}/∑w(Fo2)2]1/2. e Notcorrected. f [C45H39FeNOPPd]ClO4‚C3H6O.
for recording the 31P-decoupled H NMR spectra.
1
1
(CDCl3): δ +18.6. NMR data for the minor isomer. H NMR
(CDCl3): δ 3.82 (m, 1 H, C5H3), 4.02 (s, 5 H, C5H5), 4.07 (dd,
Supporting Information Available: Complete crystallographic
data in CIF format for compounds (Sp)-2 and (Sp)-8. This material
is available free of charge via the Internet at http://pubs.acs.org.
2JHH ) 14.7 Hz, 3JHH ) 6.2 Hz, 1 H, NHCH2Ph), 4.61 (apparent t,
3
J ) 2.7 Hz, 1 H, C5H3), 4.92 (d, JHH ) 11.6 Hz, 1 H, allyl CH
trans-O), 5.56 (m, 1 H, C5H3), 5.75 (dd, JHH ) 12.9 Hz, JPH
3
3
)
OM700542S
8.6 Hz, 1 H, allyl CH trans-P), 6.12 and 6.86-7.76 (m, 25 H, 5 ×
3
Ph), 8.40 (t, JHH ) 6.5 Hz, 1 H, NH); signals due to NHCH2Ph
(41) Otwinowski, Z.; Minor, W. HKL Denzo and Scalepack Program
Package; Nonius BV: Delft, The Netherlands. For a reference, see:
Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307-326.
(42) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.;
Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.; Spagna,
R. J. Appl. Crystallogr. 1999, 32, 115-119.
(43) Sheldrick, G. M. SHELXL97, Program for Crystal Structure Refine-
ment from Diffraction Data; University of Goettingen: Germany, 1997.
(44) Spek, A. L. Platon, a multipurpose crystallographic tool; Utrecht
University: Utrecht, The Netherlands, 2003, and updates. Available via
the Internet at http://www.cryst.chem.uu.nl/platon/.
and allylic meso-CH (δH ca. 6.9 ppm) are obscured by other signals.
31P{1H} NMR (CDCl3): δ +19.1.
X-ray Crystallography. Crystals suitable for single-crystal X-ray
diffraction analysis were grown from ethyl acetate-hexane ((Sp)-
2: orange plate, 0.03 × 0.18 × 0.42 mm3) and from acetone-
diethyl ether ((Sp)-8‚Me2CO: orange prism, 0.20 × 0.30 × 0.55
mm3). Full-set diffraction data ((h(k(l; 2θ e 55°) were collected
on a Nonius KappaCCD diffractometer equipped with a Cryostream
Cooler (Oxford Cryosystems) at 150(2) K using graphite-mono-