Synthesis of the new chiral tridentate ligand bis(pyrid-2-ylethyl) menthylphosphine and its use in the palladium-catalyzed allylic alkylations

Article abstract of DOI:10.1016/j.jorganchem.2006.01.036

We describe the synthesis of a new asymmetric P,N,N′-tridentate ligand (bis(pyrid-2-ylethyl) menthylphosphine, BPEMP), containing two pyridyl rings and (1S,2R,5S)-menthylphosphino group. The ligand is obtained in five steps from natural abundant l-menthol. The coordination behavior of the ligand toward cationic (allylic)Pd(II) moiety and its first application in palladium-catalyzed asymmetric allylic alkylation are presented. Crystallographic and spectroscopic analyses reveal that [(η³-allylic)Pd(BPEMP)]⁺ complex forms only one isomer in the solid state as well as in solution.

Full text of DOI:10.1016/j.jorganchem.2006.01.036

Journal of Organometallic Chemistry 691 (2006) 2483–2488
www.elsevier.com/locate/jorganchem
Synthesis of the new chiral tridentate ligand bis(pyrid-2-ylethyl)
menthylphosphine and its use in the palladium-catalyzed allylic
alkylations
*
Makoto Minato , Takefumi Kaneko, Shogo Masauji, Takashi Ito
Department of Materials Chemistry, Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku,
Yokohama 240-8501, Japan
Received 6 December 2005; received in revised form 5 January 2006; accepted 6 January 2006
Available online 3 March 2006
Abstract
We describe the synthesis of a new asymmetric P,N,N0-tridentate ligand (bis(pyrid-2-ylethyl) menthylphosphine, BPEMP), containing
two pyridyl rings and (1S,2R,5S)-menthylphosphino group. The ligand is obtained in five steps from natural abundant l-menthol. The
coordination behavior of the ligand toward cationic (allylic)Pd(II) moiety and its first application in palladium-catalyzed asymmetric
allylic alkylation are presented. Crystallographic and spectroscopic analyses reveal that [(g3-allylic)Pd(BPEMP)]+ complex forms only
one isomer in the solid state as well as in solution.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Palladium; Chiral tridentate ligand; Allylic alkylation; Asymmetric induction
1. Introduction
dant materials [1]. Along these lines, we designed a new
chiral tridentate ligand (bis(pyrid-2-ylethyl) menthylphos-
phine), abbreviated BPEMP (Chart 1), which was obtained
in five steps from inexpensive l-menthol. It has been recog-
nized that chiral tridentate ligands generally form a deeper
chiral concave pocket around the metal center than the cor-
responding chiral bidentate ligands [2].
In this ligand, we envisioned that due to chiral
(1S,2R,5S)-menthyl group, the two labile pyridyl groups
become diastereotopic, so as to make its metal complexes
asymmetric. In addition, this heteroatomic donor ligand
possesses both ‘‘hard’’ nitrogen and ‘‘soft’’ phosphorus cen-
ters. Such heterofunctional ligands containing soft and hard
donor sites are of considerable current interest in connec-
tion with the development of novel homogeneous catalysts
[3]. For example, the previously reported bis(pyrid-2-
ylethyl) cyclohexylphosphine, which is closely related to
BPEMP, is a promising ligand for palladium-catalyzed
dimerization of isoprene with carbon dioxide [3b]. This tri-
dentate ligand was found to be more effective than tricy-
clohexyl-phosphine in the transformation; it is conceivable
The development of transition metal complexes contain-
ing chiral ligands to catalyze asymmetric organic reactions
represents one of the most important achievements of mod-
ern organometallic chemistry, and high selective catalysts
are now available to catalyze an impressive range of reac-
tions. Progress in asymmetric catalysis relies on the design
of new chiral ligands. The vast majority of these ligands
exhibiting high enantioselectivity have been prepared by
taking advantage of elaborated asymmetric molecules as
starting materials; the synthesis of these optically pure
starting materials often involves tedious routes that are
limited to only one antipode or require a resolution step.
Consequently, difficult and specialized procedures involved
in preparing these ligands limit their synthetic potential.
Thus, special efforts have been devoted toward the synthe-
sis of easily accessible ligands based on high natural abun-
*
Corresponding author. Fax: +81 45 339 3933.
E-mail address: minato@ync.ac.jp (M. Minato).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.01.036

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M. Minato et al. / Journal of Organometallic Chemistry 691 (2006) 2483–2488
However, the reduction of 3 with LiAlH4 in the presence
of trimethylsilyl chloride proceeded in a straightforward
manner to produce 4 in reasonable yield (70%) [7]. The tri-
dentate ligand (5) was prepared from 4 by adaptation of a
method described by Toto and Doi for the synthesis of
(pyrid-2-ylethyl)diphenylphosphine [8]. Thus subsequent
treatment of 4 with 2 equiv. of distilled 2-vinylpyridine in
the presence of catalytic amounts of glacial acetic acid
resulted in the formation of 5 (BPEMP). The product 5
is high-boiling (ca. 200 ꢁC at 0.05 mmHg), air-sensitive
liquid that was characterized by spectroscopic analyses.
1
In the H NMR, besides the resonances for the menthyl
group, the resonances for the pyrid-2-ylethyl groups are
observed. The pyridine protons resonate between d 6.8
and 8.5 ppm. Two sets of the ethylene resonances for the
pyrid-2-ylethyl groups are observed between d 2 and
3 ppm. In addition, the P-CH2CH2-py peaks occur at d
35.8 (JP–C = 21 Hz) and 36.4 ppm (JP–C = 13 Hz), respec-
tively in the 13C NMR spectrum. These results indicate that
the two pyridyl groups become diastereotopic; the presence
of the chiral menthyl group imparts asymmetry to the mol-
ecule and hence inequivalence of the two pyridyl groups of
the ligand. The 31P{1H} NMR spectrum of the ligand 5
shows one singlet at ꢀ22.3 ppm.
Chart 1.
that the pyridyl groups coupled with the cyclohexylphos-
phine moiety activate an intermediate g-allyl palladium
complex. Hence, we set out exploring the application of
BPEMP to a palladium catalyzed allylation reaction.
In this paper, we report (1) the ready synthesis of new
BPEMP ligand, (2) its subsequent application in the asym-
metric catalytic bond forming reaction, and (3) the synthe-
sis and structure of the cationic Pd-allyl intermediate
containing BPEMP.
2.2. Allylic substitution with BPEMP-palladium catalyst
2. Results and discussion
Next, the effectiveness of the ligand 5 in palladium cat-
alyzed allylation reactions was tested. Asymmetric catalytic
bond forming reactions promoted by palladium complexes
containing chiral ligands have become an indispensable
tool in synthetic chemistry [9]. Especially the racemic (E)-
1,3-diphenyl-3-acetoxyprop-1-ene (I) has been usually used
as a model molecule in enantioselective palladium cata-
lyzed nucleophilic allylic substitution (Scheme 2) [10].
The catalytic runs were carried out using the allylic dim-
mer complex, [Pd(g3-C3H5)Cl]2, as precatalyst and sodium
dimethyl malonate as nucleophile under the typical experi-
mental conditions defined in Table 1. The chemical identity
of the alkylated product (II) was checked by NMR. THF,
toluene, CH3CN, and CH2Cl2 were examined as solvent;
the optimum activity was obtained in THF solution. As
can be seen, the highest ee (53%) was found to be achieved
at 0 ꢁC (entry 5), while it decreased at ꢀ20 ꢁC (entry 6).
Interestingly the Pd/ligand ratio influences both the optical
and product yields (entries 10,12); the 1:4 ratio is highly
efficient in this case. Asymmetric induction exceeds 50%
in this system, although it has been recognized that the
monodentate chiral ligand derived from (1R,2S,5R)-(ꢀ)-
2.1. Synthesis of BPEMP (5)
We have synthesized this ligand through the route
shown in Scheme 1. The (ꢀ)-menthyl chloride (1) was
obtained in 84% yield from (1R,2S,5R)-(ꢀ)-menthol [4].
Treatment of 1 with a moderate excess of Mg in THF at
70 ꢁC gave the Grignard reagent 2, which then was reacted
with PCl3 to give menthyldichlorophosphine (3) [5a]. Ini-
tially, the reduction of 3 was carried out using Ph2SiH2
as reducing reagent [6], but this method did not lead to
the desired product 4; no reaction occurred up to 200 ꢁC.
Scheme 1.
Scheme 2.

M. Minato et al. / Journal of Organometallic Chemistry 691 (2006) 2483–2488
2485
Table 1
Results of asymmetric allylic alkylation of I with dimethyl malonate
catalyzed by [PdCl(C3H5)]2/BPEMP
Entry Ratio
Pd/BPEMP/I
1/4/100
Solvent Conditions
Yield (%) ee II (%)
t (h) T (ꢁC)
1
2
CH2Cl2 48
r.t.
0
r.t.
r.t.
0
ꢀ20
r.t.
r.t.
r.t.
0
36
13
80
71
63
57
70
10
47
24
56
27
26
32
22
26
53
21
12
20
23
28
20
15
1/4/100
1/4/100
1/4/100
1/4/100
1/4/100
1/4/100
1/4/100
1/2/100
1/2/100
1/6/100
1/6/100
CH2Cl2
THF
THF
8
24
8
3
4
5
6
7
8
9
10
11
12
THF
THF
24
72
Toluene 24
CH3CN
THF
THF
THF
THF
5
24
24
24
24
r.t.
0
Fig. 1. Molecular structure of 6.
menthol is ineffective as asymmetric ligand [5]. Thus, the
P–N chelation effect of BPEMP may play a crucial role
in the present asymmetric induction reaction.
Table 2
˚
Interatomic distances (A) and angles (ꢁ) for 6
Distances
Pd1–P1
Pd1–C25
Pd1–C27
C25–C26
C26–C27
2.3. Complex formation and crystal structure
2.302(2)
2.161(8)
2.279(9)
1.42(1)
Pd1–N1
Pd1–C26
P1–C11
C25–C28
C27–C34
2.122(7)
2.173(7)
1.843(8)
1.46(1)
In order to define the structure of a key intermediate in
the present reaction as well as the conformational proper-
ties of the ligand 5, [(g3-allylic)Pd(BPEMP)]+ complex
was prepared from Pd2(dba)3, BPEMP, and (E)-1,3-diphe-
nyl-3-acetoxyprop-1-ene. The resulting complex 6 (Chart 2)
was isolated as its hexafluorophosphate salt. The study of
the solid-state and solution characteristics of such 1,3-
diphenylallyl-Pd complexes has attracted considerable
interest in recent decades [11].
1.36(1)
1.49(1)
Angles
P1–Pd1–N1
P1–Pd1–C27
C25–Pd1–C26
C26–Pd1–C27
C25–C26–C27
93.3(2)
155.8(3)
38.4(3)
35.5(3)
120.5(10)
P1–Pd1–C25
N1–Pd1–C27
C25–Pd1–C27
Pd1–N1–C13
Pd1–C25–C26
99.9(2)
101.4(3)
65.9(3)
125.0(6)
71.3(4)
The complex 6 was crystallized from CH2Cl2/ethanol,
and an ORTEP plot of the cation is shown in Fig. 1. The
more important bond lengths and bond angles are given
in Table 2. A summary of the crystallographic data is given
in Table 3 (see Section 4). Interestingly unlike analogous p-
allyl palladium complexes containing chiral chelating
ligands [9,12], no diastereoisomers were observed for 6;
only the ‘exo’ isomer (the central C-atom of the allyl moi-
ety points toward the menthyl group) exists in the solid
state. The X-ray analysis shows the existence of both the
chelating and uncoordinated pyridyl moiety together with
the p-allyl ligand. As expected for [PdII(allyl)] complexes
of this type, the local coordination geometry is distorted
square planar, with the P, N, and C atoms of the allyl
group making up the ligand coordination sphere [12,13].
The six-membered chelating ring adapts a boat-like struc-
ture, which is similar to a p-allyl Pd(II) complex containing
a N,N-donor ligand [9b]. The Pd1–N1 distance of
˚
2.122(7) A is slightly shorter than that reported for [Pd-
(g3-PhCHCHCHPh)(TMEDA)]+ (A, 2.161(3) A) [11a].
˚
˚
Furthermore, the Pd1–P1 bond length of 2.302(2) A is also
˚
shorter than that of 2.342(1) A in the related bis(triphenyl-
phosphine) complex [Pd(g3-PhCHCHCHPh)(PPh3)2]+ (B)
[14]. These observations demonstrate that the P, N donors
of BPEMP are attached rigidly to the central metal.
Although the bond lengths and bond angles of the (g3-
allylic)Pd core are within the expected range reported for
several related complexes involving p-allyl ligands, there
are some features in the structure of 6 that are worthy of
note. The significantly smaller C25–Pd–C27 angle
(65.9(3)ꢁ) in 6 versus that in A (67.4(2)ꢁ) coincides with
longer Pd–C bond distances observed in the former. This
included angle is found to be intermediate between A and
B (64.9(2)ꢁ). The Pd–C bond to the terminal allylic C-atom
trans to the P-atom is significantly longer than that to the
˚
Chart 2.
C-atom trans to the N-atom (Pd1–C27 = 2.279(9) A,

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M. Minato et al. / Journal of Organometallic Chemistry 691 (2006) 2483–2488
Table 3
3. Conclusion
Summary of crystal data for 6
We have shown that a new asymmetric P,N,N0-triden-
Empirical formula
Formula weight
Temperature
Crystal dimensions
Crystal system
Space group
C39H48F6N2P2Pd
827.16
23 ꢁC
0.30 · 0.18 · 0.15 mm
Orthorhombic
P212121 (# 19)
Primitive
tate ligand (BPEMP) incorporating two pyridyl rings and
(1S,2R,5S)-menthylphosphino group is easily obtained in
five steps from natural abundant l-menthol. The applica-
tion of the resulting ligand in the asymmetric Pd-catalyzed
allylic alkylation led to the formation of the alkylated
product with enantiomeric excesses up to 53% ee. Since
the menthyl group is generally regarded as ineffective chiral
auxiliary for asymmetric ligands, the discriminative coordi-
nation of one of the pyridyl rings in BPEMP is considered
as the source of asymmetric induction.
The chirality on this new ligand can be readily fine-
tuned by incorporating different chiral groups. Thus, the
present simple synthetic approach allows the preparation
of a great variety of chiral tridentate ligands having a
breadth of electronic and steric properties.
Lattice type
Lattice parameters
˚
a (A)
17.667(4)
20.585(6)
10.892(3)
106.34(5)
3960(1)
4
1.387
1704.00
6.07
˚
b (A)
˚
c (A)
b (ꢁ)
3
˚
V (A )
Z value
Dcalcd (g/cm3)
F(000)
l(Mo Ka) (cmꢀ1
)
Number of reflections used for unit
cell determination (2h range)
2h max (ꢁ)
25 (28.3–30.0ꢁ)
60.0
Scan rate
Number of reflections measured
16.0ꢁ/min (in x) (up to 3 scans)
Total: 6479
4. Experimental
Unique: 6352 (Rint = 0.206)
6327
4.1. General procedures
Number of reflections
(all, 2h < 60.02ꢁ)
Number of variables
Residuals: R; Rw
Goodness-of-fit
451
0.130; 0.167
1.32
Unless otherwise noted, all manipulations were con-
ducted using standard Schlenk techniques under purified
argon or nitrogen. Commercially available reagent grade
chemicals were used as such without any further purifica-
tion. All solvents were dried by standard methods and were
stored under argon. The new compounds were character-
ized by IR, 1H, 13C, and 31P{1H} NMR spectroscopy.
C–H COSY decoupling experiment was used to gain addi-
tional structure information. All NMR spectra were
recorded on a JEOL-JNM-270 spectrometer. 31P{1H}
NMR peak positions were referenced to external PPh3.
(ꢀ)-Menthyl chloride [4], menthyldichlorophosphine [5a],
(E)-1,3-diphenyl-3-acetoxyprop-1-ene [18], and [Pd(g3-
C3H5)Cl]2 [19] were prepared according to the published
methods.
˚
Pd1–C25 = 2.161(8) A). This is an expression of the higher
trans influence of the phosphine ligand [15]. For the P,N-
ligand systems developed by Pfaltz and Helmchen [16],
and Brown et al. [17], it is generally agreed that the nucle-
ophilic attack takes place preferentially at the allyl termi-
nus trans to phosphorus. Thus, attack at this position
allows one to rationalize the observed enantiomer in the
catalytic experiment.
A detailed NMR assignment for the complex was made
by comparison and by analogy with the NMR data for the
related p-allyl palladium complexes containing P,N-het-
erodonating ligands [9,12] and the ligand BPEMP itself.
The 31P{1H} NMR spectrum at room temperature shows
only one sharp resonance, which is shifted downfield by
about 70 ppm with respect to that of 5, verifying that the
phosphorus atom is coordinated to the metal center in
4.2. Synthesis of menthylphosphine (4)
A two-necked, round-bottomed flask equipped with a
gas inlet, a dropping funnel, and a stirrer was flushed with
N2. The flask was charged with LiAlH4 (5.51 g, 145 mmol)
suspended in THF (74 ml), which was cooled to ꢀ60 ꢁC.
Under rapid stirring, trimethylsilyl chloride (18.4 ml,
145 mmol) was added slowly to the flask from the dropping
funnel. After the addition was complete, the mixture was
allowed to warm to room temperature and was stirred
for 120 min. It was then cooled to ꢀ60 ꢁC once more,
whereupon menthyldichlorophosphine (3, 11.1 g, 46 mmol)
in THF (110 ml) was carefully added. After the addition
was complete, the mixture was allowed to warm to room
temperature and was stirred for 36 h. The resulting mixture
was treated with water (37 ml) and aq NaOH (1 M, 74 ml),
and then extracted with diethyl ether (3 · 100 ml). The
combined organic layers were evaporated under reduced
1
solution. On the other hand, the H NMR spectrum of 6
reveals a broad doublet centered at about 8.45 ppm, assign-
able to the proton resonances of the 6-position of the pyr-
idyl rings. This value was sifted downfield by only
0.04 ppm with respect to that of 5 and we were unable to
distinguish unequivocally between the free and the coordi-
1
nated pyridine in the H NMR spectrum, thus suggesting
that the pyridine group is weakly coordinated in solution.
Taking into account the hemilabile character of BPEMP
ligand, these behaviors are not unexpected. The allyl moi-
ety gives only one set of signals in the 13C NMR spectrum
(68.77, C25; 75.26, C27; 109.87, C26), which is in accord
with the X-ray diffraction data. Namely complex 6 forms
only one isomer in solution as well as in the solid state.

M. Minato et al. / Journal of Organometallic Chemistry 691 (2006) 2483–2488
2487
pressure. Fractional distillation of the crude product gave
solution of sodium dimethyl malonate was added the former
by a syringe, and the combined mixture was stirred at 0 ꢁC
for 24 h. The reaction mixture was partitioned between ether
and water. The organic layer was separated, and the aqueous
layer was extracted with ether. The combined organic layer
was washed with brine, dried over anhydrous Na2SO4, and
then concentrated in vacuo. The residue was purified by a
column chromatography (SiO2; n-hexane/ethyl acetate (15/
1)) to give the alkylated product (II, 63%). The chemical
identity of the product was checked by NMR. Evaluation
of the optical yields was performed by HPLC using a com-
mercial CHIRALCEL OD column.
menthylphosphine (4, 5.54 g, 70% yield, 102 ꢁC/18 mmHg).
3
1H NMR (270 MHz, C6D6): d = 2.99 (ddd, JH–H
=
2
1
5.5 Hz, JH–H = 12.2 Hz, JP–H = 55.8 Hz, 1H, PH), 2.29
(ddd, JH–H = 5.5 Hz, JH–H = 12.2 Hz, JP–H = 55.8 Hz,
3
2
1
1H, PH), 2.09 (m, 1H, CH(CH3)2), 0.60–1.80 (m, 9H, ring
3
protons of the menthyl group), 0.85 (d, 3H, JH–H
=
3
6.9 Hz, CH(CH3)2), 0.79 (d, 3H, JH–H = 6.3 Hz, CH3),
3
0.71 (d, 3H, JH–H = 6.9 Hz, CH(CH3)2).
13C NMR (C6D6): d = 48.1 (CHCH(CH3)2), 46.7
(PCHCH2), 35.4 (CH3CHCH2), 34.0 (PCH), 30.2
(CH3CH), 29.4 ((CH3)2CH), 25.3 ((CH3)2CHCHCH2),
22.5 (CH3), 21.7 ((CH3)2CH), 15.2 ((CH3)2CH).
31P NMR (C6D6): d = ꢀ116.3.
4.5. Synthesis of [Pd(g3-PhCHCHCHPh)(BPEMP)]þPF ꢀ6 (6)
4.3. Synthesis of BPEMP (5)
A Schlenk flask equipped with a stirrer was flushed with
N2. The flask was charged with BPEMP (5, 76 mg,
0.199 mmol), Pd2(dba)3 (92 mg, 0.100 mmol), and dry
CH2Cl2 (10 ml). To the resulting solution was added (E)-
1,3-diphenyl-3-acetoxyprop-1-ene (I, 50 mg, 0.199 mmol),
and the combined mixture was stirred at room temperature
for 30 min. During this period the solution changed from
dark purple to dark green. The solvent was removed at
reduced pressure, and the remaining content was washed
with n-hexane (15 ml · 3). To the residue was added
KPF6 (50 mg, 0.27 mmol) and acetone (5 ml), and the mix-
ture was stirred at room temperature for 12 h. After
removal of the solvent under reduced pressure, the residual
mixture was washed with n-hexane (15 ml · 3) and then
extracted with CH2Cl2. The solution was filtered through
a filter paper and the resulting orange solution was evapo-
rated to dryness. The residue was recrystallized (CH2Cl2/
ethanol) in a refrigerator. Compound 6 was obtained as a
yellow plate (107 mg, 63%).
A Schlenk flask equipped with a condenser and a stirrer
was flushed with N2. The flask was charged with menthyl-
phosphine (4, 5.49 g, 32 mmol), glacial acetic acid
(0.70 ml), and distilled 2-vinylpyridine (8.76 ml, 81 mmol).
The solution was heated with stirring at 150 ꢁC for 8 h. The
crude mixture was dissolved in methanol (30 ml) and made
basic with solid potassium carbonate. The precipitate was
removed by suction filtration through Celite and the filtrate
was concentrated under vacuum to give a viscous oil. Frac-
tional distillation of the crude product gave BPEMP (5,
6.15 g, 50% yield, ca. 200 ꢁC/0.05 mmHg) as a yellow vis-
cous oil. The compound was found to be air-sensitive
and had to be stored under N2.
1H NMR (270 MHz, C6D6): d = 8.40 ꢀ 8.60 (m, 2H, H6
of pyridyl ring), 6.65–7.30 (m, 6H, pyridyl ring), 2.80–3.15
(m, 4H, PCH2CH2-py) 2.73 (m, 1H, CH(CH3)2), 0.60–2.15
(m, 13H, ring protons of the menthyl group and PCH2-
3
CH2-py), 0.84 (d, 3H, JH–H = 6.9 Hz, CH(CH3)2), 0.84
1H NMR (270 MHz, C6D6): d = 8.34 ꢀ 8.50 (m, 2H, H6
of pyridyl ring), 7.13–7.80 (m, 16H, CHarom), 6.61–6.81 (m,
1H, PhCHCHCHPh), 5.64–5.76 (m, 1H, PhCHCHCHPh
(trans to P)), 4.83–4.93 (m, 1H, PhCHCHCHPh (trans to
N)), 3.00–3.27 (m, 4H, PCH2CH2-py) 2.78–2.85 (m, 1H,
CH(CH3)2), 0.42–1.81 (m, 18H, ring protons of the men-
thyl group, PCH2CH2-py, CH(CH3)2, and CH3).
3
3
(d, 3H, JH–H = 6.9 Hz, CH3), 0.83 (d, 3H, JH–H
6.9 Hz, CH(CH3)2).
=
13C NMR (C6D6): d = 162.6 ꢀ 120.9 (C5H4N), 44.9–
22.0 (ring carbons of the menthyl group, CH(CH3)2, and
PCH2CH2-py), 36.4 (PCH2CH2-py), 35.8 (PCH2CH2-py),
22.7 (CH3), 21.6 ((CH3)2CH), 15.3 ((CH3)2CH).
31P NMR (C6D6): d = ꢀ22.3.
13C NMR (C6D6): d = 143.2 ꢀ 128.3 (py and Ph), 109.9
(C26), 75.3 (C27), 68.8 (C25), 44.6–24.7 (ring carbons of
the menthyl group, CH(CH3)2, and PCH2CH2-py), 36.3
(PCH2CH2-py), 35.9 (PCH2CH2-py), 22.5 (CH3), 21.7
((CH3)2CH), 15.5 ((CH3)2CH).
IR (neat): 2951, 2923, 1591, 1568, 1472, 1434, 771, 750.
4.4. Enantioselective Pd-catalyzed allylic alkylation
Experiments were carried out at different temperatures,
different reaction times, and different catalyst concentrations
in various kinds of solvents as reported in Table 1. A typical
procedure is as follows. The catalytic precursor was gener-
ated in situ from [Pd(g3-C3H5)Cl]2 (3.1 mg, 0.0086 mmol)
and BPEMP (5, 13.1 mg, 0.0344 mmol) in THF (3.0 ml)
for 40 min before adding a solution of (E)-1,3-diphenyl-3-
acetoxyprop-1-ene (I, 0.200 g, 0.80 mmol) in THF (1.0 ml).
In a separate flask, dimethyl malonate (0.19 ml, 1.65 mmol)
was added to a slurry of hexane-washed sodium hydride
(38 mg, 1.59 mmol) in THF (3.0 ml). To the resulting clear
31P NMR (CDCl3): d = 50.7.
IR (KBr): 3059, 3026, 2958, 2869, 1737, 1651, 1624,
1603, 1575, 1494, 1449, 1339, 1189, 1099, 1017, 984, 838.
4.6. X-ray crystal structure analysis of 6
A simple crystal of 6 was mounted on a glass fiber. All
measurements were made on a Rigaku AFC-7R diffrac-
˚
tometer by using Mo Ka radiation (k = 0.71069 A) with
l = 6.07 cmꢀ1 and F(000) = 1704.00 A. The unit-cell
˚
parameters were obtained from a least-squares refinement

2488
M. Minato et al. / Journal of Organometallic Chemistry 691 (2006) 2483–2488
(c) Y. Kiso, K. Yamamoto, K. Tamao, M. Kumada, J. Am. Chem.
Soc. 94 (1972) 4373.
using the setting angles of 25 carefully centered reflections
in the range 28.3ꢁ 5 2h 5 30.0ꢁ. The parameters used dur-
ing the collection of diffraction data are given in Table 3.
The structure was solved and expanded by using Fourier
techniques. The non-hydrogen atoms were refined aniso-
tropically. Hydrogen atoms were included but not refined.
CCDC reference number 291390. See http://www.rsc.
org/suppdata/dt/b2/b209624m/ for crystallographic data
in CIF or other electronic format.
[6] H. Fritzche, U. Hasserodt, F. Korte, Chem. Ber. 98 (1965) 1681.
[7] E.P. Kyba, S.-T. Liu, R.L. Harris, Organametallics 2 (1983) 1877.
[8] S.D. Toto, J.T. Doi, J. Org. Chem. 52 (1987) 4999.
[9] (a) J. Sprinz, M. Kiefer, G. Helmchen, M. Reggelin, G. Huttner, O.
Walter, L. Zsolnai, Tetrahedron Lett. 35 (1994) 1523;
(b) P. von Matt, G.C. Lloyd-Jones, A.B.E. Minidis, A. Pfaltz, L.
Macko, M. Neuburger, M. Zhender, H. Ruegger, P. Pregosin, Helv.
¨
Chim. Acta 78 (1995) 265.
[10] See for example: (a) J. Tsuji, Palladium Reagents and Catalysts,
Wiley, Chichester, England, 1996, p. 290;
(b) B.M. Trost, D.L. Van Kanken, Chem. Rev. 96 (1996) 395;
(c) B.M. Trost, C. Lee, in: I. Ojima (Ed.), Catalytic Asymmetric
Synthesis, second ed., Wiley–VCH, New York, 2000, p. 593.
[11] (a) P. Barbaro, P.S. Pregosin, R. Salzmann, A. Albinati, R.W. Kunz,
Organometallics 14 (1995) 5160;
Acknowledgement
We are grateful to Dr. Yoshitaka Yamaguchi of Yoko-
hama National University for an X-ray structure analysis.
´
(b) F. Fernandez, M. Gomez, S. Jansat, G. Muller, E. Martin, L.
Flores-Santos, P.X. Garcia, A. Acosta, A. Aghmiz, M. Gimenez-
Pedros, A.M. Masdeu-Bulto, M. Dieguez, C. Claver, M.A. Maestro,
Organometallics 24 (2005) 3946.
References
[1] See for example: (a) A. Roucoux, L. Thieffry, J.-F. Carpentier, M.
[12] N. Baltzer, L. Macko, S. Schaffner, M. Zehnder, Helv. Chim. Acta
79 (1996) 803.
[13] A. Togni, U. Burckhardt, V. Gramlich, P.S. Pregosin, R. Salzmann,
J. Am. Chem. Soc. 118 (1996) 1031.
[14] C. Amatore, A.A. Bashsoun, A. Jutand, L. Mensah, G. Meyer, L.
Ricard, Organometallics 24 (2005) 1569.
[15] T.G. Appleton, H.C. Clark, L.E. Manzer, Coord. Chem. Rev. 10
(1973) 335.
[16] P. von Matt, O. Loiseleur, G. Koch, A. Pfaltz, C. Lefeber, T.
Feucht, G. Helmchen, Tetrahedron: Asymmetry 5 (1994) 573.
[17] J.M. Brown, D.I. Hulmes, P.J. Guiry, Tetrahedron 50 (1994)
4493.
[18] P.R. Aubun, P.B. Mackenzie, B. Bosnich, J. Am. Chem. Soc. 107
(1985) 2033.
´
Devocelle, C. Meliet, F. Agbossou, A. Mortreux, Organometallics 15
(1996) 2440;
(b) J.-C. Shi, L.-J. Chen, X.-Y. Huang, D.-X. Wu, B.-S. Kang, J.
Organomet. Chem. 535 (1997) 17.
[2] (a) C. Bianchini, E. Farnetti, L. Glendenning, M. Graziani, G.
Nardin, M. Peruzzini, E. Rocchini, F. Zanobini, Organometallics 14
(1995) 1489;
(b) Y. Jiang, Q. Jiang, X. Zhang, J. Am. Chem. Soc. 120 (1998) 3817.
[3] (a) A. Bader, E. Lindner, Coord. Chem. Rev. 108 (1991) 27;
(b) H. Hoberg, M. Minato, J. Organomet. Chem. 406 (1991) C25.
[4] J.G. Smith, G.F. Wright, J. Org. Chem. 17 (1952) 1116.
[5] (a) M. Hidai, H. Mizuta, H. Yagi, Y. Nagai, K. Hata, Y. Uchida, J.
Organomet. Chem. 232 (1982) 89;
(b) S. Yamago, M. Yanagawa, H. Mukai, E. Nakamura, Tetrahedron
52 (1996) 5091;
[19] W.T. Dent, R. Long, A.J. Wilkinson, J. Chem. Soc. (1964) 1585.