Ionic-salt-tagged ferrocenyl diphosphine-imine ligands and their application to palladium-catalyzed asymmetric allylic etherification

Article abstract of DOI:10.1016/j.tetasy.2011.07.025

A new type of ferrocenyl diphosphine-imine ligands that contains an ionic salt group has been prepared, and successfully applied to asymmetric C*-O bond formation. In the Pd-catalyzed asymmetric allylic etherification of 1,3-diphenyl-2-propenyl acetate, h

Full text of DOI:10.1016/j.tetasy.2011.07.025

Tetrahedron: Asymmetry 22 (2011) 1379–1389
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Tetrahedron: Asymmetry
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Ionic-salt-tagged ferrocenyl diphosphine–imine ligands and their application
to palladium-catalyzed asymmetric allylic etherification
Li Dai a, Xin Li a, Hao Yuan a, Xia Li a, Zhihuai Li a, Di Xu a, Fan Fei a, Yingqiang Liu a, Jun Zhang a,
Zhiming Zhou a,b,
⇑
a School of Chemical Engineering and the Environment, Beijing Institute of Technology, 5 Zhongguancun South Street, Haidian District, Beijing 100081, PR China
b State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
A new type of ferrocenyl diphosphine–imine ligands that contains an ionic salt group has been prepared,
and successfully applied to asymmetric C⁄–O bond formation. In the Pd-catalyzed asymmetric allylic
etherification of 1,3-diphenyl-2-propenyl acetate, high enantioselectivity was obtained (up to 91.0%
ee). The potential of the catalysts to be recycled and reused has also been demonstrated.
Ó 2011 Elsevier Ltd. All rights reserved.
Received 19 May 2011
Accepted 25 July 2011
Available online 27 August 2011
1. Introduction
ate to afford the branched allylic ethers in yields of 86–88% with
96–97% ee. Haight et al. reported an asymmetric variant of the
Chiral ferrocene ligands are differentiated from other common
ligands by their unique sandwich structure. They have become
the subject of increasing interest in all fields of organometallic
chemistry.1 Chiral ferrocene ligands can be applied to many types
of asymmetric catalysis. In metal-catalyzed asymmetric allylic sub-
stitution reactions, these ligands act as a powerful tool in the syn-
thesis of valuable small complex natural products.2 Over the past
few years, many chiral ferrocene ligands have been prepared as
1,2-disubstituted ferrocenes that possess both central and planar
chirality. Some of these ligands have played key roles in the devel-
opment of important catalytic systems in industrial processes.
Among these ligands, ferrocenyl phosphine–imine-type ligands
have been developed by Hayashi,3 Chung,4 and Zheng.5 Such
ligands have unique flexible coordination behavior associated with
tunable steric and electronic properties. These properties also
provide enantioselectivity in asymmetric allylic alkylation and
asymmetric hydrosilylation reactions.
The allylic alkylation reaction is one of the most popular and
well-documented model reactions for the palladium-catalyzed
asymmetric C–C and C–N bond formation.6 In contrast, the enantio-
selective allylic substitution of allylic substrates to C–O formation
with a lower nucleophilicity of alcohols has rarely been studied be-
cause of the relatively hard oxygen nucleophiles and inherent flex-
ible chains. Nevertheless, Hartwig7a,b noted that in the presence of
an iridium catalyst containing a phosphoramidite ligand, lithium
p-methoxyphenolate or lithium 2,4-dimethyl-3-pentanolate may
be allylated with p-methoxycinnamyl acetate or cinnamyl carbon-
protocol.8c However, more reactive allylic carbonate and harsher
conditions were required, and the observed enantioselectivities
were poor. Recently, Chan7c observed the palladium-(Sp,R)-ferro-
NPS-catalyzed asymmetric allylic etherification of 1,3-diphenyl-2-
propenyl acetate with a wide array of aliphatic alcohols with
good-to-excellent enantioselectivities (up to 96% ee).
The recovery of chiral catalysts is a specific avenue of current
research.9 Due to the high cost of the coordinating metal and the
preparation of the ligand used in the transition-metal-catalyzed
asymmetric reactions, expanding this type of reaction to industrial
production levels is usually difficult. Therefore, an ideal catalyst
would be capable of being recovered and maintaining its catalytic
efficiency in the required catalytic system. The recovery of a catalyst
that could be effectively used in asymmetric allylic etherification
has not been reported. Therefore, following our previous report on
the synthesis of quaternary-ammonium-salt-tagged ferrocenyl
monophosphine–imine ligands and their successful application to
palladium-catalyzed asymmetric allylic substitution,10 this study
focuses on ligands tagged with ionic-liquid groups. Such ligands fa-
vor both an enhancement of the reactivity and the recovery of the
catalyst. Herein, we report a series of chiral ferrocenyl diphos-
phine–imine ligands with good catalytic activity when applied to
an asymmetric etherification reaction. We also report the results
of our investigation into the recycling and reuse of the catalyst.
2. Results and discussion
2.1. Ligand synthesis
The new chiral ferrocenyl diphosphine–imine ligands for the
asymmetric allylic etherification reaction were synthesized from
⇑
Corresponding author. Tel./fax: +86 10 68918982.
E-mail address: zzm@bit.edu.cn (Z. Zhou).
0957-4166/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetasy.2011.07.025

1380
L. Dai et al. / Tetrahedron: Asymmetry 22 (2011) 1379–1389
NMe2
NMe2
1) n-BuLi
1) Ac2O
2) n-BuLi/TMEDA
PPh2
PPh2
Fe
Fe
Fe
Fe
3) PPh2Cl
2)NH3·H2O
CHO
R
FDPIL3-a, X=PF6
FDPIL3-b, X=I
FDPIL3-c, X=Br
FDPIL3-d, X=OTs
FDPIL3-e, X=NO3
NH2
PPh2
PPh2
N
PPh2
N
X
MgSO4
PPh2
(R,Sp)-FDPIL3
N
N
I
PPh2
N
PPh2
I
N
Fe
Fe
PPh2
PPh2
(S,Rp)-FDPIL1
(R,Rp)-FDPIL2
N
N
N
I
N
PPh2
PPh2
Fe
Fe
I
PPh2
PPh2
(R,Sp)-FDPIL5
(R,Sp)-FDPIL4
N
N
N
N
N
N
PPh2
PPh2
Fe
Fe
Br
Br
NO2
PPh2
PPh2
(R,Sp)-FDPIL7
(R,Sp)-FDPIL6
N
N
N
N
PPh2
PPh2
Fe
Fe
Br
PPh2
PPh2
(R,Sp)-FDPIL8
(R,Sp)-FDPIL-A
Scheme 1. Preparation of chrial ferrocenyl diphosphine–imine ligands.
the versatile ferrocenyl amine known as Ugi amine (Scheme 1). The
amine material was dissolved in dry oxygen-free ethyl ether, and
the temperature was decreased to ꢀ78 °C. Next, n-BuLi was added
via syringe into the solution. The reaction was allowed to occur for
1 h at room temperature, and the mixture solution containing
TMEDA and n-BuLi was added slowly at ꢀ78 °C. The reaction was
then maintained for 5 h at room temperature. The reaction solu-
tion was then cooled to ꢀ78 °C for a third time prior to the injec-
tion of the reagent PPh2Cl. The solution was stirred overnight at
room temperature to afford 1-(10,2-bisdiphenylphosphinyl) ferr-
ocenyl amine. The amine was finally reacted with the appropriate
aldehyde containing the ionic-liquid group, which resulted in the
formation of the target ligands.11
2.2. Catalytic reactivity of FDPIL in a Pd-catalyzed asymmetric
allylic etherification
We first tested the reactivity of chiral ferrocenyl diphosphine–
imine ligands (FDPILs) that contained the ionic groups. Thus, un-
der catalysis of the [Pd]/ligand complex, the asymmetric allylic
etherification reaction conditions were optimized in terms of the
enantioselectivity and conversion. A variety of solvents, palladium
precursors, Pd/ligand ratios, equivalents of base and nucleophile,
reaction solution consistencies and temperatures were investi-
gated. The results are summarized in Table 1.
In our previous study,10 we found that the solvent used in the
catalysis system had a strong effect on the yields and ee values of

L. Dai et al. / Tetrahedron: Asymmetry 22 (2011) 1379–1389
1381
Table 1
Optimization of the asymmetric allylic etherification reaction parametersa
OH
OBn
OAc
[Pd]/(R,Sp)-FDPIL3-PF6
2a
1a
b
Entry Solvent
[Pd]
[Pd]/lig. (%/%) Base
Cs2CO3
Base/Sub (mol/mol) BnOH/Sub (mol/mol) Concd (mg/mL) Temp (°C) Yield (%) eec (%)
1
2
3
4
5
6
7
8
9
CH2Cl2
Toluene
CH3CN
DMF
[Pd(
[Pd(
[Pd(
[Pd(
[Pd(
g
g
g
g
g
g
g
g
3-C3H5)Cl]2
3-C3H5)Cl]2
3-C3H5)Cl]2
3-C3H5)Cl]2
3-C3H5)Cl]2
3-C3H5)Cl]2
3-C3H5)Cl]2
3-C3H5)Cl]2
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:4
5:6
5:10
10:10
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:5
5:5
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
1
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
1
2.5
3.5
5
3
3
3
3
3
3
3
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
16
64
128
32
32
32
128
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
40
30
0
43 51.2
68 43.8
73 55.8
62 46
49 59.8
55 40.4
52 46.8
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
K2CO3
DMSO
CH3COCH3 [Pd(
THF [Pd(
[Bmim]PF6 [Pd(
—
—
CH3CN
Pd2(dba)3ꢁCH3Cl
42 59.2
39 66.6
51 86.8
58 80.8
48 87.8
35 85.2
61 88.6
49 83.2
38 79
10 CH3CN
11 CH3CN
12 CH3CN
13 CH3CN
14 CH3CN
15 CH3CN
16 CH3CN
17 CH3CN
18 CH3CN
19 CH3CN
20 CH3CN
21 CH3CN
22 CH3CN
23 CH3CN
24 CH3CN
25 CH3CN
26 CH3CN
27 CH3CN
28 CH3CN
29 CH3CN
30 CH3CN
31 CH3CN
Pd(dba)2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Pd (CH3CN)2Cl2
Cs2CO3
Cs2CO3 2.5
Cs2CO3 3.5
50 83.4
57 85.5
61 76.6
13 82.5
43 85.4
53 85.2
62 73.8
17 88
50 83.5
86 72.7
61 79.8
54 81.8
25 81
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
5
3
3
3
3
3
3
3
3
3
3
3
0
45 55.8
a
b
c
All reactions were performed in 2 mL of solvent for 4 h with a molar ratio of [Pd]/ligand/M2CO3/substrate/BnOH = 5–10/4–10/100–500/100/100–500.
Isolated yield based on the substrate.
Determined by chiral HPLC analysis. The absolute configuration was determined to be (R) by comparing the specific rotation with the literature value.8c
the product catalyzed by the quaternary-ammonium-salt-tagged
phosphine ferrocenyl–imine ligands in the palladium-catalyzed
asymmetric allylic substitution. These results indicated that a suit-
able solvent should be determined first. The asymmetric allylic
etherification reactions were performed on a 0.5 mmol scale. There-
fore, 1,3-diphenyl-2-propenyl acetate reacted with 3.0 equiv of ben-
zyl alcohol in the presence of 5.0 mol % (R,Sp)-FDPIL3-a,
tivity decreased (Table 1, entries 12–15). When the complex
concentration was 10 mol %, no significant increase in the selectiv-
ity or enantioselectivity of the product was observed.
Variations in the species of base used in the catalytic etherification
were also studied (Table 1, entry 16). No product formed when ace-
tate, which is a relatively weak base, was used. Presumably, in this
case, no significant quantity of effective nucleophilic O-reactant
was produced for the reaction to take place. The catalyzed etherifica-
tion did proceed to completion when cesium carbonate was used as
the added base, whereas both the yield and stereoselectivity were
slightly decreased when potassium carbonate was used as the base.
These results might be attributable to the weaker alkalinity of potas-
siumcarbonate compared to cesium carbonate. Accordingly, no prod-
uctwasdetectedwhen mucha weakerbase, suchasLi2CO3 orNa2CO3,
was used. The amount of base was also related to the results. Both the
reaction yield and enantioselectivity increased as the amount of ce-
sium carbonate was increased. When more than 3 equiv of base were
used, the yield increased, but the stereoselectivity decreased (Table 1,
entries 17–20). To enhance the yield of the reactions, the quantity of
benzylalcoholwas investigatedfrom1 to5 equiv ofthesubstrate(Ta-
ble 1, entries 21–24). The yield increased significantly with increasing
the benzyl alcohol content and it reached its highest value with
3 equiv of benzyl alcohol. When more than 3 equiv of benzyl alcohol
were added, the yield continued to increase, but the ee value de-
creased. The concentration of the substrates also had an effect (Ta-
ble 1, entries 25–27). Higher concentrations afforded higher yields
but with diminished enantioselectivity, which paralleled the results
5.0 mol %[Pd(g
3-C3H5)Cl]2, and 3.0 equiv of cesium carbonate,
which furnished moderate yields and ee values. The polar solvent
CH2Cl2 produced better results than non-polar solvents such as tol-
uene (Table 1, entries 1–8) because of the better solubility of the
ferrocenyl diphosphine–imine ligands in CH2Cl2. The product yield
was satisfactory in the more polar solvent acetonitrile (Table 1,
entry 3). Due to these results, acetonitrile was fixed as the solvent
for the subsequent reactions. Such solvent-effect trends were also
observed by Trost,12 who attributed the observed behavior to the
more stabile reactants; the higher stability led to a decrease in the
rate of nucleophilic attack. Consequently, the amount of product
formed increased because of the non-kinetically formed intermedi-
ate p-allyl complexes. No product was obtained when an ionic liquid
was used as the solvent (Table 1, entry 8) in this catalyst reaction be-
cause of the insolubility of the ligand in such a solvent system.
Of the four different catalyst precursors tested in this step,
Pd(CH3CN)2Cl2 provided the highest enantioselectivity with a mod-
erate yield (Table 1, entry 11). The best result was exhibited by a
1:1 ratio of [Pd] to ligand at 5 mol %. When the palladium precur-
sor or ligand was present in excess, the yield or the enantioselec-

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L. Dai et al. / Tetrahedron: Asymmetry 22 (2011) 1379–1389
Table 2
Ligand effects on the asymmetric allylic etherificationa
OH
OBn
OAc
[Pd]/FDPIL, Cs2CO3
1a
2a
CH3CN, r.t., 4h
Entry
Ligand
Yieldb (%)
eec (%)
Config.
1
2
3
4
5
6
7
8
9
10
11
12
13
FDPIL1
FDPIL2
48
25
39
58
43
37
40
52
43
34
30
32
16
86.4
8.8
(S)
(S)
(R)
(R)
(R)
(R)
(R)
(R)
(R)
(R)
(R)
(R)
(R)
FDPIL3-a
FDPIL3-b
FDPIL3-c
FDPIL3-d
FDPIL3-e
FDPIL4
FDPIL5
FDPIL6
FDPIL7
FDPIL8
86.6
87.2
87.1
86.4
84.4
83.2
86.8
79.2
85.5
81.2
67
FDPIL-A
a
All reactions were carried out in 2 mL of CH3CN at 20 °C for 4 h in the presence of 0.5 mmol of the substrate, with a molar ratio of Pd (CH3CN)2Cl2/
ligand/Cs2CO3/substrate/BnOH = 5/5/300/100/300.
b
Isolated yield based on the substrate.
c
Determined by chiral HPLC analysis. The absolute configuration was determined by comparing the specific rotation with the literature value.8c
observed by Trost12 when phenol was used as a reactant. Tempera-
ture was also an important factor for etherification. Increasing the
temperature shortened the reaction time, but the yield and enanti-
oselectivity were lower than those observed at room temperature.
For the reaction at 0 °C, the enantioselectivity did not increase as
much as expected (Table 1, entries 28–31).
different anions on FDPIL3 (Table 2, entries 3–7). Under the same
conditions, the ligand containing iodide ion performed better than
the others. This trend is in contrast to the previous observations re-
ported in the literature,13 yet is fully consistent with our experi-
mental results observed with allylic alkylation.10 We assumed
that in our case, a dominant pathway that affects the catalytic
activity may exist, that is, the presence of the softer anionic Iꢀ ions
are better suited for keeping the counter-cation electropositive and
After optimization, the reaction parameters were fixed at
32 mg/mL of substrate in CH3CN, 1,3-diphenyl-2-propenyl acetate
reacted with 3.0 equiv of benzyl alcohol in the presence of
5.0 mol % ligand-3-PF6, 5.0 mol % Pd(CH3CN)2Cl2, and 3.0 equiv of
cesium carbonate at 20 °C. Under the optimal experimental condi-
tions, the influence of the substituents attached to the aryl ring, the
steric properties of the quaternary ammonium salt unit, and the
nature of the anions on the catalytic activity and enantioselectivity
were investigated. The results are listed in Table 2. All of the li-
gands gave better enantioselectivities and yields than FDPIL-A,
which did not contain ionic groups. These results imply that the io-
nic groups tagged to the ferrocenyl diphosphine–imine moiety had
a positive influence on the catalytic reactivity. This prompted us to
first determine the synergetic combination of chiral elements on
the novel ferrocenyl ligands tagged with ionic groups. We designed
and prepared ligands 1, 2 and 3 with different chiral element com-
binations. Hence, the experimental results showed that (R,Sp) was
the matched chirality combination for both activity and selectivity
of the reaction, which was then fixed for the subsequent design of
the ligands to examine the allylic etherification.
thus transmitting the electron-withdrawing effect through the
p-
conjugation system to positively coordinate the imine atom (vide
infra). However, the possibility of the Iꢀ ion behaving as a weak li-
gand of palladium (a promoter of p–r–p interconversion of the al-
lyl complex intermediates) should not be excluded. The presence
of the electronically weaker-coordinating counter ions (Table 2,
entry 3) or those of larger size (Table 2, entry 6) were also observed
to reduce the reactivities of the corresponding catalysts.
The ferrocenyl diphosphine–imine ligands containing different
cationic imidazolium salts were also synthesized (Table 2, en-
tries 8–12). A comparison of the catalytic results from FDPIL5
and FDPIL6 showed that the quaternary ammonium salt was
superior to the imidazolium salt, possibly because of the greater
strength of the electron-withdrawing effects of the attached cat-
ionic moiety. Consequently, FDPIL3-b performed better than
FDPIL4 because FDPIL3 possessed an appropriate spacing be-
tween the ionic group and the catalytic center. Apparently, the
catalytic effect of FDPIL3-b was better than that of FDPIL5 be-
cause the electron-withdrawing effect from the quaternary
ammonium salt was transferred to the imine nitrogen atom
The counter anions have been well documented as significantly
affecting the rate and the enantioselectivity in the palladium-cata-
lyzed allylic substitution reaction. Togni13a examined this anion ef-
fect on the allylic alkylation using ferrocenyl ligands and found
that the addition of hard anions (such as fluoride) exhibited a ben-
eficial effect on the enantioselectivity of allylic aminations. Åker-
mark et al.13b reported that the addition of 0.1 equiv of chloride
through the
p-conjugation, thus improving the catalytic activity
of the catalyst (Table 2, entries 8 and 9). Analogously, we de-
duced that the presence of the imidazolium groups on FDPIL 6
and 8 that are bridged by one methylene to the phenyl ring ex-
erts a lesser influence on the catalytic results, as shown in the
experiments (Table 2, entries 10 and 12). The introduction of
an additional electron-withdrawing group, such as a nitro group,
onto the phenyl ring (Table 2, entries 10 and 11) slightly im-
proved the enantioselectivity of the reaction.
decreased the equilibration time of the syn,anti-r-allyl complexes
to 0.5 h compared to 48 h when tetrafluoroborate was used as the
counterion.13b The authors also confirmed that the order of effec-
tiveness was Fꢀ > Clꢀ > Brꢀ > Iꢀ for the allylic alkylation of phenols
in the presence of added halides.
These findings encouraged us to investigate the role of counte-
rions in etherification. The ligands were devised to contain several
To understand the coordination status of such ligands with palla-
dium, we attempted to determine the structures of the complexesby
X-ray diffraction; however, we were unsuccessful because of the

L. Dai et al. / Tetrahedron: Asymmetry 22 (2011) 1379–1389
1383
instability of the complexes in air. Fortunately, some structural
information was obtained from the in situ generation of a palladium
(0) complex in an NMR tube (43 mg FDPIL3-b with 5.6 mg [Pd(g-
to the corresponding ortho- and para-reactants (Table 3, entries
1–3). Among the para-halogens, chlorine resulted in the highest
ee values. When electron-donating substituents, such as methoxy
groups, were attached to the ring, the observed trends were similar
to those of the fluorine analogs. A phenol was also used as a
nucleophile, and a moderate yield but lower enantioselectivity
was produced (Table 3, entry 12). The Pd/FDPIL3 catalyst was also
found to be compatible with heterocycles (Table 3, entry 11).
However, aliphatic alcohols did not react in this catalyst system.
Next, 1,3-diphenyl-2-propenyl benzyl ester was used as the other
substrate in the asymmetric allylic etherification reaction.
Accordingly, several nucleophiles were tested in the catalytic sys-
tem, which showed that the Pd/FDPIL 3 catalyst could adapt to the
substrates (Table 4). However, decreases in both yields and ee values
were observed for almost all of the corresponding reagents.
C3H5)Cl]2, molar ratio 1:1 in CDCl3). The disappearance of the C@N
carbon resonance at 157.65 Hz in the 13C spectra of free FDPIL3-b
and the 31P–31P coupling (d 30.20, 34.48, 2JPP = 23 Hz) revealed that
a tridentate coordination complex formed during the reaction. This
complex might be responsible for the complex’s effective catalytic
behavior.
To further extend the scope of this reaction with respect to the
alcohol reactants, ortho- and meta-substituted benzyl alcohols
were applied successfully in the asymmetric allylic etherification
reaction. The results are presented in Tables
3 and 4. The
electron-withdrawing fluorine substituent at the meta-position of
the phenyl ring afforded a higher yield and selectivity compared
Table 3
Enantioselective allylic etherification 1,3-diphenyl-2-propenyl acetate with a variety of alcohols under the catalysis of a Pd–L3-I complexa
OAc
OR
[Pd]/(R,Sp)-FDPIL3-I
Cs2CO3
+
ROH
CH3CN, r.t., 4h
1a
2b-n
Entry
1
R-OH
Sub.
Prod.
Yieldb (%)
53
eec (%)
84.6
OH
1a
1a
2b
F
OH
OH
2
3
2c
69
74
82.4
88.2
F
1a
2d
F
Cl
OH
4
5
6
7
1a
1a
1a
1a
2e
2f
60
58
5
91
89
9
OH
Br
OH
2g
2h
MeO
OH
39
59
OMe
OH
8
1a
2i
52
74.2
OMe
OH
9
10
11
1a
1a
1a
2j
56
39
49
74.2
59
OH
2k
2l
O
OH
74.4
OH
12
1a
2m
52
7
OH
13
1a
2n
58
22.8
Cl
a
The reaction was carried out in 2 mL of CH3CN at 20 °C for 4 h in the presence of 0.5 mmol of the substrate, with a molar ratio of Pd (CH3CN)2Cl2/L3-I/Cs2CO3/substrate/
Nu-H = 5/5/300/100/300.
b
Isolated yield based on the substrate.
Determined by chiral HPLC analysis.
c

1384
L. Dai et al. / Tetrahedron: Asymmetry 22 (2011) 1379–1389
Table 4
Enantioselective allylic etherification 1,3-diphenyl-2-propenyl benzyl ester with a variety of alcohols under the catalysis of a Pd–L3-I complexa
O
O
Ph
OR
[Pd]/(R,Sp)-FDPIL3-I
+
Cs2CO3
ROH
CH3CN, r.t., 4h
1b
2b-l
Entry
1
R-OH
Sub.
Prod.
Yieldb (%)
48
eec (%)
80.2
OH
1b
2b
F
OH
OH
2
3
1b
1b
2c
35
60
77
F
2d
84.6
F
Cl
OH
OH
4
5
1b
1b
2e
2f
67
63
72.6
85.4
Br
OH
6
7
1b
1b
2g
2l
32
43
84.8
85
MeO
O
OH
a
The reaction was carried out in 2 mL of CH3CN at 20 °C for 4 h in the presence of 0.5 mmol of the substrate, with a molar ratio of Pd (CH3CN)2Cl2/L3-I/Cs2CO3/substrate/
Nu-H = 5/5/300/100/300.
b
Isolated yield based on the substrate.
Determined by chiral HPLC analysis.
c
2.3. Catalyst recycling
tagged ionic group plays a positive role on the reactivity and selec-
tivity of this asymmetric allylic etherification reaction compared to
the corresponding neutral ligand. The reactivity and selectivity in-
In our previous studies,10 we investigated the possibility of
recovering and reusing the ferrocenyl phosphine–imine ligands
for asymmetric allylic alkylation and amination reactions. In fact,
the yields and ee values for asymmetric allylic alkylation decreased
sharply when the catalysts were reused after recovery, and the col-
or of the catalysts became darker during the reactions. Herein, after
the asymmetric allylic etherification reaction was complete, the
Pd/ligand complex was not as darkly colored as the catalysts used
for asymmetric allylic alkylation after the completed reaction.
Therefore, we considered trying to reuse the catalysts. The etheri-
fication was still conducted in CH3CN, and the nucleophilic reagent
used was 4-chlorobenzyl alcohol (Table 5).
creased primarily because of the increased rate of the
p–r–p inter-
conversion of the -allyl complex intermediates. Under the
p
optimal reaction conditions, the Pd–FDPIL3-b catalyst afforded
moderate product yields and high ee values (up to 91%). Further-
more, our investigation showed that such ligands have the poten-
tial to be recovered and reused.
4. Experimental
4.1. General methods
The solvent was removed by vacuum filtration after the com-
pletion of each catalytic etherification process. Absolute ether
was then added to the Schlenk flask to separate the product from
the dry residues. The remaining catalyst was reused in subsequent
reactions without further treatment.
After being recycled three times, the enantioselectivity of the
desired product did not significantly decrease; however, the cata-
lytic capability decreased sharply. This decrease might be attribut-
able to the loss of the catalyst by absolute ether during washing.
All reactions were carried out under an argon atmosphere un-
less otherwise noted. Air- or water-sensitive liquids and solu-
tions were transferred via
a syringe or a stainless steel
cannula. All solvents were degassed and dried using standard
methods prior to use.14 Commercially available reagents were
used as received without further purification. The [Pd(g3
-
C3H5)Cl]2, Pd(CH3CN)2Cl2, and Pd2(dba)3ꢁCHCl3 were purchased
from Alfa Aesar, and PPFNH2 was prepared using the method de-
scribed in the literature.3,5a–c The 1H NMR spectra were recorded
at 300 MHz. Chemical shifts (d) were given in ppm relative to
TMS for 1H NMR, to the residual solvent peak for 13C NMR,
and to H3PO4 as an external standard for 31P NMR. Specific rota-
tions were measured on a Perkin–Elmer 341 polarimeter. The IR
spectra were measured in wavenumbers on a Nicolet Magna IR-
560. The enantiomeric excesses were determined on a Knauer
HPLC system.
3. Conclusion
A series of chiral ferrocenyl diphosphine–imine ligands tagged
with ionic salt groups has been designed and synthesized. These li-
gands were successfully applied to the asymmetric allylic etherifi-
cation reaction, which demonstrated that the presence of the

L. Dai et al. / Tetrahedron: Asymmetry 22 (2011) 1379–1389
1385
Table 5
Catalyst recycle in the asymmetric allylic etherification reactiona
Cl
OAc
O
[Pd]/(R,Sp)-FDPIL3-I
OH
+
Cs2CO3
CH3CN, r.t., 4h
Cl
1a
2e
Recycle time
1
R-OH
Yieldb (%)
60
eec (%)
91
OH
OH
OH
Cl
Cl
Cl
2
3
32
10
89.1
73.5
a
The reaction was carried out in 2 mL of CH3CN at 20 °C for 4 h in the presence of 0.5 mmol of the substrate, with a molar ratio of Pd(CH3CN)2Cl2/L3-I/
Cs2CO3/substrate/Nu-H = 5/5/300/100/300.
b
Isolated yield based on substrate.
Determined by chiral HPLC analysis.
c
4.2. Preparation of ligands
(300 MHz, DMSO-d6): d 1.44 (d, 3H, J = 6.6 Hz, CHCH3), 3.46–3.56
(m, 2H, Cp-H), 3.56 (s, 9H, CH3), 4.11–4.14 (m, 2H, Cp-H), 4.23 (s,
1H, Cp-H), 4.61 (s, 1H, Cp-H), 4.71 (s, 1H, Cp-H), 4.72 (m, 1H,
CHMe), 6.87–7.75 (m, 24 H, Ph-H), 8.11 (s, 1H, N@CH). 13C NMR
4.2.1. FDPIL1
An argon-purged Schlenk flask was charged with 4-formyl-
N,N,N-trimethyl-benzenaminium iodide (291 mg, 1.0 mmol),
(S,Rp)-BPPFNH2 (627 mg, 1.05 mmol), and MgSO4 (500 mg). Next,
3 mL of absolute alcohol were added dropwise, and the solution
was stirred at 78 °C for 2 h. The reaction mixture was monitored
by TLC until completion. The MgSO4 was filtered, and the solvent
was removed under reduced pressure. The yellow crude product
was purified by ethyl ether and then recrystallized from CH2Cl2
to give FDPIL1 (783 mg, 90% yield) as a yellow solid. Mp 174–
(100 MHz, CDCl3)
d 25.99 (CHMe), 58.03 (NMe3), 63.86 (d,
J = 9 Hz, Cp), 65.85 (Cp), 69.44 (Cp), 71.07 (d, J = 3 Hz, Cp), 71.56
(d, J = 18 Hz, Cp), 72.89 (CHMe), 73.24 (d, J = 9 Hz, Cp), 73.64
(Cp), 74.69 (d, J = 10z, Cp), 99.36 (d, J = 23 Hz, Cp), 120.60 (Ph-C),
128.15 (Ph-C), 128.33 (Ph-C), 128.65 (Ph-C), 129.16 (Ph-C),
120.36 (Ph-C), 132.65 (d, J = 18 Hz, Ph-C), 132.92 (d, J = 19 Hz, Ph-
C), 133.76 (d, J = 20 Hz, Ph-C), 134.90 (d, J = 21 Hz, Ph-C), 136.91
(d, J = 9 Hz, Ph-C), 138.41 (d, J = 13 Hz, Ph-C), 139.53 (d, J = 10 Hz,
Ph-C), 148.14 (C-NMe3), 156.30 (s, C@N). 31P NMR (160 MHz,
DMSO-d6): d ꢀ19.30 (s, 1P, PPh2), ꢀ25.89 (s, 1P, PPh2). MALDI:
m:z = 743.2 M+; ESI: m:z = 127 Mꢀ. Anal. Calcd for C46H45FeIN2P2:
C, 63.46; H, 5.21; N, 3.22. Found: C, 63.81; H, 5.50; N, 3.41.
176 °C.
½
a 2D5
ꢂ
¼ ꢀ336:9 (c 0.3, CH2Cl2). IR (KBr) 1641.8(s),
1474.3(s), 1432.6(s), 1168.5(m), 1106.3(m), 564.8(s). 1H NMR
(300 MHz, DMSO-d6): d 1.45 (d, 3H, J = 6.3 Hz, CHCH3), 3.44–3.57
(m, 2H, Cp-H), 3.57 (s, 9H, CH3), 4.12–4.14 (m, 2H, Cp-H), 4.24 (s,
1H, Cp-H), 4.55 (s, 1H, Cp-H), 4.60 (s, 1H, Cp-H), 4.73 (m, 1H,
CHMe), 6.82–7.77 (m, 24H, Ph-H), 8.12 (s, 1H, N@CH). 13C NMR
4.2.3. FDPIL3-a
(100 MHz, CDCl3):
d
25.99 (CHMe), 58.03 (NMe3), 63.86 (d,
An argon-purged Schlenk flask was charged with 4-formyl-
N,N,N-trimethyl-benzenaminium hexafluorophosphate (309 mg,
1 mmol), (R,Sp)-BPPFNH2 (627 mg, 1.05 mmol), and Na2SO4
(500 mg). Next, CH2Cl2 (3 mL) was added dropwise, and the solu-
tion was stirred at room temperature for 3 h. The reaction mixture
was monitored by TLC until completion. The Na2SO4 was filtered,
and the solvent was removed under reduced pressure. The yellow
crude product was purified by ethyl ether to give FDPIL3-a
J = 9 Hz, Cp), 65.85 (Cp), 69.44 (Cp), 71.07 (d, J = 3 Hz, Cp), 71.56
(d, J = 18 Hz, Cp), 72.89 (CHMe), 73.24 (d, J = 9 Hz, Cp), 73.64
(Cp), 74.69 (d, J = 10z, Cp), 99.36 (d, J = 23 Hz, Cp), 120.60 (Ph-C),
128.15 (Ph-C), 128.33 (Ph-C), 128.65 (Ph-C), 129.16 (Ph-C),
120.36 (Ph-C), 132.65 (d, J = 18 Hz, Ph-C), 132.92 (d, J = 19 Hz, Ph-
C), 133.76 (d, J = 20 Hz, Ph-C), 134.90 (d, J = 21 Hz, Ph-C), 136.91
(d, J = 9 Hz, Ph-C), 138.41 (d, J = 13 Hz, Ph-C), 139.53 (d, J = 10 Hz,
Ph-C), 148.14 (C-NMe3), 156.30 (s, C@N). 31P NMR (160 MHz,
DMSO-d6): d ꢀ19.30 (s, 1P, PPh2), ꢀ25.89 (s, 1P, PPh2). MALDI:
m:z = 743.2 M+; ESI: m:z = 127 Mꢀ. Anal. Calcd for C46H45FeIN2P2:
C, 63.46; H, 5.21; N, 3.22. Found: C, 63.58; H, 5.12; N, 3.28.
(852 mg, 96% yield) as
a
yellow solid. Mp 216–219 °C.
½ ꢂ
a 2D5
¼ ꢀ340:4 (c 0.6, CH2Cl2). IR (KBr) 1640.6, 1473.3, 1433.3,
1166.0, 1105.7, 565.2. 1H NMR (300 MHz, DMSO-d6): d 1.44 (d,
3H, J = 6.6 Hz, CHCH3), 3.44–3.57 (m, 2H, Cp-H), 3.57 (s, 9H, CH3),
4.13 (m, 2H, Cp-H), 4.23 (s, 1H, Cp-H), 4.54 (s, 1H, Cp-H), 4.59 (s,
1H, Cp-H), 4.73 (m, 1H, CHMe), 6.81–7.76 (m, 24 H, Ph-H), 8.11
(s, 1 H, N@CH). 13C NMR (100 MHz, DMSO-d6): d 21.44 (CHMe),
56.57 (NMe3), 63.64 (d, J = 6 Hz, Cp), 71.02 (d, J = 7 Hz, Cp), 72.38
(d, J = 5 Hz, Cp), 73.00 (d, J = 6 Hz, Cp), 74.10 (CHMe), 74.92 (d,
J = 20 Hz, Cp), 75.88 (d, J = 11 Hz, Cp), 76.38 (d, J = 9 Hz, Cp),
96.76 (d, J = 23 Hz, Cp), 120.07 (Ph-C), 127.58 (Ph-C), 127.82 (d,
J = 6 Hz, Ph-C), 128.27 (Ph-C), 128.36 (Ph-C), 128.44 (Ph-C),
128.51 (Ph-C), 128.65 (Ph-C), 128.93 (Ph-C), 129.08 (Ph-C),
129.40 (Ph-C), 132.06 (d, J = 19 Hz, Ph-C), 132.90 (d, J = 19 Hz, Ph-
C), 133.36 (d, J = 20 Hz, Ph-C), 134.90 (d, J = 21 Hz, Ph-C), 136.67
(d, J = 9 Hz, Ph-C), 137.03 (Ph-C), 138.15 (d, J = 11 Hz, Ph-C),
138.66 (d, J = 10 Hz, Ph-C), 139.13 (d, J = 10 Hz, Ph-C), 148.11
4.2.2. FDPIL2
An argon-purged Schlenk flask was charged with 4-formyl-
N,N,N-trimethyl-benzenaminium iodide (291 mg, 1.0 mmol),
(R,Rp)-BPPFNH2 (627 mg, 1.05 mmol), and MgSO4 (500 mg). Next,
3 mL of absolute alcohol were added dropwise, and the solution
was stirred at 78 °C for 2 h. The reaction mixture was monitored
by TLC until completion. The MgSO4 was filtered, and the solvent
was removed under reduced pressure. The yellow crude product
was purified by ethyl ether and then recrystallized from CH2Cl2
to give FDPIL2 (800 mg, 92% yield) as a yellow solid. Mp 153–
155 °C.
½
a 2D5
ꢂ
¼ þ316:2 (c 0.3, CH2Cl2). IR (KBr) 1642.8(s),
1473.9(s), 1435.2(s), 1164.8(m), 1106.1(m), 564.8(s). 1H NMR

1386
L. Dai et al. / Tetrahedron: Asymmetry 22 (2011) 1379–1389
(C-NMe3), 157.65 (C@N). 31P NMR (160 MHz, DMSO-d6): d ꢀ19.15
(s, 1P, PPh2), ꢀ25.81 (s, 1P, PPh2), 144.27 (m, 1P, J = 672 Hz, PF6).
MALDI: m:z = 743.3 M+, ESI: m:z = 145 M-. Anal. Calcd for
4.2.6. FDPIL3-d
An argon-purged Schlenk flask was charged with 4-formyl-
N,N,N-trimethyl-benzenaminium
trifluoromethanesulfonate
C
46H45F6FeN2P3: C, 62.17; H, 5.10; N, 3.15. Found: C, 62.19; H,
(313 mg, 1 mmol), (R,Sp)-BPPFNH2 (627 mg, 1.05 mmol), and
MgSO4 (500 mg). Next, 3 mL of absolute alcohol were added drop-
wise, and the solution was stirred at 78 °C for 2 h. The reaction
mixture was monitored by TLC until completion. The MgSO4 was
filtered, and the solvent was removed under reduced pressure.
The yellow crude product was purified by ethyl ether to give
FDPIL3-d (856 mg, 95% yield) as a yellow solid. Mp 168–171 °C
5.21; N, 3.05.
4.2.4. FDPIL3-b
An argon-purged Schlenk flask was charged with 4-formyl-
N,N,N-trimethyl-benzenaminium iodide (291 mg, 1.0 mmol),
(R,Sp)-BPPFNH2 (627 mg, 1.05 mmol), and MgSO4 (500 mg). Next,
3 mL of absolute alcohol were added dropwise, and the solution
was stirred at 78 °C for 2 h. The reaction mixture was monitored
by TLC until completion. The MgSO4 was filtered, and the solvent
was removed under reduced pressure. The yellow crude product
was purified by ethyl ether to give FDPIL3-b (809 mg, 93% yield)
½
a 2D5
ꢂ
¼ ꢀ362:3 (c 0.6, CH2Cl2). IR (cmꢀ1): 1640.6, 1473.3, 1433.3,
1166.0, 1105.7, 565.2. 1H NMR (300 MHz, DMSO-d6): d 1.44 (d,
3H, J = 5.4 Hz, CHCH3), 3.33–3.56 (m, 2H, Cp-H), 3.44 (s, 9 H,
CH3), 4.12–4.14 (m, 2H, Cp-H), 4.23 (s, 1 H, Cp-H), 4.55 (s, 1H,
Cp-H), 4.59 (s, 1H, Cp-H), 4.69–4.75 (m, 1H, CHMe), 6.81–7.76
(m, 28 H, Ph-H), 8.111 (s, 1 H, N@CH). 13C NMR (100 MHz,
DMSO-d6): d 21.28 (PHMe), 21.89 (CHMe), 56.85 (NMe3), 63.93
(Cp), 71.33 (Cp), 72.67 (Cp), 73.28 (Cp), 74.38 (CHMe), 75.17 (d,
J = 20 Hz, Cp), 76.19 (d, J = 11 Hz, Cp), 76.70 (d, J = 9 Hz, Cp),
97.11 (d, J = 22 Hz, Cp), 120.49 (Ph-C), 125.99 (Ph-C), 127.99 (Ph-
C), 128.14 (Ph-C), 128.53 (Ph-C), 128.75 (Ph-C), 128.91 (Ph-C),
129.23 (Ph-C), 129.35 (Ph-C), 129.71 (Ph-C), 132.35 (d, J = 19 Hz,
Ph-C), 133.21 (d, J = 18 Hz, Ph-C), 133.65 (d, J = 20 Hz, Ph-C),
135.20 (d, J = 21 Hz, Ph-C), 137.05 (d, J = 9 Hz, Ph-C), 137.28 (Ph-
C), 138.05 (Ph-C), 138.48 (d, J = 10 Hz, Ph-C), 139.00 (d, J = 9 Hz,
Ph-C), 139.43 (d, J = 11 Hz, Ph-C), 146.34 (Ph-S), 148.51 (C-NMe3),
158.03 (C@N). 31P NMR (160 MHz, DMSO-d6) d ꢀ18.93 (s, 1P,
PPh2), ꢀ25.51 (s, 1P, PPh2). MALDI: m:z = 743.3 M+, ESI:
m:z = 171.0 Mꢀ. Anal. Calcd for C52H51FeN2O3P2S: C, 69.25; H,
5.70; N, 3.11. Found: C, 69.49; H, 5.72; N, 3.05.
as a yellow solid. Mp 172–175 °C. ½a D25
¼ ꢀ337:3 (c 0.6, CH2Cl2).
ꢂ
IR (KBr) 1640.6, 1473.3, 1433.3, 1166.0, 1105.7, 565.2. 1H NMR
(300 MHz, DMSO-d6): d 1.44 (d, 3H, J = 6.6 Hz, CHCH3), 3.46–3.56
(m, 2H, Cp-H), 3.56 (s, 9 H, CH3), 4.11–4.14 (m, 2H, Cp-H), 4.23
(s, 1 H, Cp-H), 4.61 (s, 1H, Cp-H), 4.71 (s, 1H, Cp-H), 4.72 (m, 1H,
CHMe), 6.87–7.75 (m, 24 H, Ph-H), 8.11 (s, 1 H, N@CH). 13C NMR
(100 MHz, DMSO-d6): d 21.42 (CHMe), 56.52 (NMe3), 63.63 (d,
J = 6 Hz, Cp), 70.92 (d, J = 5 Hz, Cp), 72.25 (d, J = 5 Hz, Cp), 72.88
(d, J = 6 Hz, Cp), 73.98 (CHMe), 74.79 (d, J = 20 Hz, Cp), 75.77 (d,
J = 11 Hz, Cp), 76.28 (d, J = 9 Hz, Cp), 96.68 (d, J = 23 Hz, Cp),
120.13 (Ph-C), 127.51 (Ph-C), 127.74 (d, J = 6 Hz, Ph-C), 128.21
(Ph-C), 128.30 (Ph-C), 128.39 (Ph-C), 128.46 (Ph-C), 128.60 (Ph-
C), 128.86 (Ph-C), 128.95 (Ph-C), 129.34 (Ph-C), 131.95 (d,
J = 18 Hz, Ph-C), 132.81 (d, J = 19 Hz, Ph-C), 133.26 (d, J = 20 Hz,
Ph-C), 134.80 (d, J = 22 Hz, Ph-C), 136.58 (d, J = 9 Hz, Ph-C),
136.91 (Ph-C), 138.05 (d, J = 10 Hz, Ph-C), 138.61 (d, J = 10 Hz, Ph-
C), 139.02 (d, J = 10 Hz, Ph-C), 148.08 (C-NMe3), 157.65 (C@N).
31P NMR (160 MHz, DMSO-d6): d ꢀ19.30 (s, 1P, PPh2), ꢀ25.89 (s,
1P, PPh2). MALDI: m:z = 743.3 M+, ESI: m:z = 127 Mꢀ. Anal. Calcd
for C46H45FeIN2P2: C, 63.46; H, 5.21; N, 3.22. Found: C, 63.69; H,
5.22; N, 3.20.
4.2.7. FDPIL3-e
An argon-purged Schlenk flask was charged with 4-formyl-
N,N,N-trimethyl-benzenaminium nitrate (226 mg, 1 mmol),
(R,Sp)-BPPFNH2 (627 mg, 1.05 mmol), and Na2SO4 (500 mg). Next,
CH2Cl2 (3 mL) was added dropwise, and the solution was stirred
at room temperature for 2 h. The reaction mixture was monitored
by TLC until completion. The Na2SO4 was filtered, and the solvent
was removed under reduced pressure. The yellow crude product
was purified by ethyl ether to give FDPIL3-e (732 mg, 91% yield)
4.2.5. FDPIL3-c
An argon-purged Schlenk flask was charged with 4-formyl-
N,N,N-trimethyl-benzenaminium bromide (244 mg, 1 mmol),
(R,Sp)-BPPFNH2 (627 mg, 1.05 mmol), and MgSO4 (500 mg). Next,
3 mL of absolute alcohol were added dropwise, and the solution
was stirred at 78 °C for 3 h. The reaction mixture was monitored
by TLC until completion. The MgSO4 was filtered, and the solvent
was removed under reduced pressure. The yellow crude product
was purified by EtOH to give FDPIL3-c (781 mg, 95% yield) as a yel-
as a yellow solid. Mp 170–172 °C. ½a D25
¼ ꢀ341:5 (c 0.6, CH2Cl2).
ꢂ
IR (KBr) 1640.6, 1473.3, 1433.3, 1166.0, 1105.7, 565.2. 1H NMR
(300 MHz, DMSO-d6): d 1.47 (d, 3H, J = 5.4 Hz, CHCH3), 3.42–3.55
(m, 2H, Cp-H), 3.55 (s, 9 H, CH3), 4.11–4.21 (m, 3H, Cp-H), 4.52–
4.69 (m, 2H, Cp-H), 4.74 (m, 1H, CHMe), 6.80–7.74 (m, 20 H, Ph-
H), 8.09 (s, 1H, N@CH). 13C NMR (100 MHz, DMSO-d6): d 19.98
(CHMe), 56.30 (NMe3), 64.30 (d, J = 7 Hz, Cp), 70.93 (Cp), 72.67 (d,
J = 4 Hz, Cp), 73.18 (d, J = 10 Hz, Cp), 73.64 (CHMe), 74.79 (d,
J = 19 Hz, Cp), 75.98 (d, J = 9 Hz, Cp), 77.00 (d, J = 9 Hz, Cp), 95.88
(d, J = 24 Hz, Cp), 119.41 (Ph-C), 127.11 (Ph-C), 127.47 (d, J = 6 Hz,
Ph-C), 127.83 (Ph-C), 127.90 (Ph-C), 128.19 (Ph-C), 128.45 (Ph-C),
129.13 (Ph-C), 129.58 (Ph-C), 132.18 (d, J = 18 Hz, Ph-C), 132.92
(d, J = 19 Hz, Ph-C), 133.31 (d, J = 20 Hz, Ph-C), 134.99 (d,
J = 21 Hz, Ph-C), 136.56 (d, J = 8 Hz, Ph-C), 137.17 (Ph-C), 138.45
(d, J = 10 Hz, Ph-C), 138.94 (d, J = 8 Hz, Ph-C), 139.25 (d, J = 10 Hz,
Ph-C), 148.07 (C-NMe3), 159.24 (C@N). 31P NMR (160 MHz,
DMSO-d6): d ꢀ18.00 (s, 1P, PPh2), ꢀ25.47 (s, 1P, PPh2). MALDI:
m:z = 743.3 M+, ESI: m:z = 62 Mꢀ. Anal. Calcd for C46H45FeN3O3P2:
C, 68.58; H, 5.63; N, 5.22. Found: C, 69.01; H, 5.42; N, 5.09.
low solid. Mp 176–177 °C. ½a D25
¼ ꢀ339:7 (c 0.6, CH2Cl2). IR (KBr)
ꢂ
1640.6, 1473.3, 1433.3, 1166.0, 1105.7, 565.2. 1H NMR (300 MHz,
DMSO-d6): d 1.44 (d, 3H, J = 6.6 Hz, CHCH3), 3.32–3.42 (m, 2H,
Cp-H), 3.43 (s, 9 H, CH3), 4.11–4.13 (m, 2H, Cp-H), 4.23 (s, 1 H,
Cp-H), 4.54 (s, 1H, Cp-H), 4.59 (s, 1H, Cp-H), 4.71 (m, 1H, CHMe),
6.81–7.75 (m, 24 H, Ph-H), 8.11 (s, 1 H, N@CH). 13C NMR
(100 MHz, DMSO-d6): d 21.89 (CHMe), 52.30 (NMe3), 63.72 (d,
J = 6 Hz, Cp), 71.33 (d, J = 11 Hz, Cp), 72.57 (s, Cp), 73.21 (Cp),
74.32 (s, CHMe), 75.19 (d, J = 20 Hz, Cp), 76.04 (d, J = 10 Hz, Cp),
76.69 (d, J = 9 Hz, Cp), 97.45 (d, J = 23 Hz, Cp), 127.51 (Ph-C),
128.05 (d, J = 5 Hz, Ph-C), 128.35 (d, J = 6 Hz, Ph-C), 128.68 (Ph-C),
128.76 (Ph-C), 128.82 (Ph-C), 128.96 (Ph-C), 129.23 (Ph-C),
129.75 (Ph-C), 130.17 (Ph-C), 132.31 (d, J = 18 Hz, Ph-C), 132.80
(s, Ph-C), 133.20 (d, J = 19 Hz, Ph-C), 133.65 (d, J = 20 Hz, Ph-C),
135.29 (d, J = 22 Hz, Ph-C), 137.13 (d, J = 10 Hz, Ph-C), 137.69 (C-
NMe3), 138.46 (d, J = 10 Hz, Ph-C), 139.42 (d, J = 11 Hz, Ph-C),
158.94 (C@N). 31P NMR (160 MHz, DMSO-d6): d ꢀ18.93 (s, 1P,
PPh2), ꢀ25.45 (s, 1P, PPh2). MALDI: m:z = 743.3 M+, ESI: m:z =
78.9, 80.9 Mꢀ. Anal. Calcd for C46H45FeBrN2P2: C, 67.09; H, 5.51;
N, 3.40. Found: C, 67.39; H, 5.42; N, 3.40.
4.2.8. FDPIL4
An argon-purged Schlenk flask was charged with 3-formyl-
N,N,N-trimethyl-benzenaminium iodide (291 mg, 1.0 mmol),
(R,Sp)-BPPFNH2 (627 mg, 1.05 mmol), and Na2SO4 (500 mg). Next,
3 mL of absolute alcohol were added dropwise, and the solution
was stirred at 78 °C for 2 h. The reaction mixture was monitored

L. Dai et al. / Tetrahedron: Asymmetry 22 (2011) 1379–1389
1387
by TLC until completion. The Na2SO4 was filtered, and the solvent
was removed under reduced pressure. The yellow crude product
was purified by ethyl ether to give FDPIL4 (835 mg, 96% yield) as
NMR (300 MHz, DMSO-d6): d 1.41 (d, 3H, J = 6.6 Hz, CHCH3), 3.46
(s, 1H, Cp-H), 3.51 (s, 1H, Cp-H), 3.86 (s, 3 H, CH3), 4.07–4.09 (m,
2H, Cp-H), 4.19 (s, 1 H, Cp-H), 4.11 (s, 1H, Cp-H), 4.55 (s, 1H, Cp-
H), 4.67 (m, 1H, CHMe), 5.37 (s, 2H, Ph-CH2), 6.75–7.73 (m, 26 H,
imidazole-H and Ph-H), 8.01 (s, 1 H, N@CH), 9.21 (s, 1H, NCHN).
13C NMR (100 MHz, DMSO-d6): d 22.26 (CHMe), 37.19 (NMe),
54.02 (Ph-CH2-N), 65.83 (Cp), 72.91 (d, J = 12 Hz, Cp), 74.36 (d,
J = 5 Hz, Cp), 74.67 (Cp), 74.96 (d, J = 10 Hz, Cp), 75.56 (CHMe),
76.72 (d, J = 9 Hz, Cp), 78.69 (d, J = 8 Hz, Cp), 98.02 (d, J = 23 Hz,
Cp), 123.96 (Ph-C), 125.74 (Ph-C), 129.29 (d, J = 6 Hz, Ph-C),
129.71 (Ph-C), 129.76 (Ph-C), 129.81 (Ph-C), 130.05 (Ph-C),
130.31 (Ph-C), 130.49 (Ph-C), 130.96 (Ph-C), 131.95 (d, J = 18 Hz,
Ph-C), 133.91 (d, J = 18 Hz, Ph-C), 134.76 (d, J = 19 Hz, Ph-C),
135.16 (d, J = 20 Hz, Ph-C), 138.81 (d, J = 20 Hz, Ph-C), 137.72 (N–
C–N), 140.24 (d, J = 10 Hz, Ph-C), 141.04 (d, J = 10 Hz, Ph-C),
162.56 (C@N). 31P NMR (160 MHz, DMSO-d6): d ꢀ17.01 (s, 1P,
PPh2), ꢀ24.89 (s, 1P, PPh2). MALDI: m:z = 780.7 M+, ESI:
m:z = 78.9, 80.9 (Mꢀ). Anal. Calcd for C48H44BrFeN3P2: C, 66.99;
H, 5.15; N, 4.88. Found: C, 67.12; H, 5.33; N, 4.60.
a yellow solid. Mp 178–180 °C. ½a D25
¼ ꢀ332:8 (c 0.6, CH2Cl2). IR
ꢂ
(KBr) 1640.6, 1473.3, 1433.3, 1166.0, 1105.7, 565.2. 1H NMR
(300 MHz, DMSO-d6): d 1.47 (d, 3H, J = 5.4 Hz, CHCH3), 3.46–3.54
(m, 2H, Cp-H), 3.54 (s, 9 H, CH3), 4.13 (s, 2H, Cp-H), 4.24 (s, 1 H,
Cp-H), 4.56 (s, 1H, Cp-H), 4.61 (s, 1H, Cp-H), 4.76 (m, 1H, CHMe),
6.84–7.90 (m, 20 H, Ph-H), 8.10 (s, 1 H, N@CH). 13C NMR
(100 MHz, DMSO-d6): d 21.85 (CHMe), 56.93 (NMe3), 63.78 (d,
J = 6 Hz, Cp), 71.39 (Cp), 72.64 (Cp), 73.28 (Cp), 74.40 (CHMe),
75.19 (d, J = 20 Hz, Cp), 76.23 (d, J = 10 Hz, Cp), 76.74 (d, J = 9 Hz,
Cp), 96.99 (d, J = 23 Hz, Cp), 119.31 (Ph-C), 122.40 (Ph-C), 127.70
(Ph-C), 128.10 (Ph-C), 128.70 (Ph-C), 128.84 (Ph-C), 128.99 (Ph-
C), 129.25 (Ph-C), 129.44 (Ph-C), 129.77 (Ph-C), 130.27 (Ph-C),
132.44 (d, J = 18 Hz, Ph-C), 133.20 (d, J = 20 Hz, Ph-C), 133.66 (d,
J = 19 Hz, Ph-C), 135.22 (d, J = 22 Hz, Ph-C), 136.94 (d, J = 9 Hz,
Ph-C), 137.84 (Ph-C), 138.45 (d, J = 10 Hz, Ph-C), 139.12 (d,
J = 10 Hz, Ph-C), 139.41 (d, J = 10 Hz, Ph-C), 147.41 (C-NMe3),
158.42 (C@N). 31P NMR (160 MHz, DMSO-d6): d ꢀ18.94 (s, 1P,
PPh2), ꢀ25.76 (s, 1P, PPh2). MALDI: m:z = 743.3 M+, ESI:
m:z = 127 Mꢀ. Anal. Calcd for C46H45FeIN2P2: C, 63.46; H, 5.21; N,
3.22. Found: C, 63.69; H, 5.22; N, 3.20.
4.2.11. FDPIL7
An argon-purged Schlenk flask was charged with 3-[(4-formyl-
3-nitro-phenyl)methyl]-1-methyl-1H-imidazolium bromide
(326 mg, 1.0 mmol), (R,Sp)-BPPFNH2 (627 mg, 1.05 mmol), and
MgSO4 (500 mg). A mixture of absolute alcohol (1.5 mL) and CH2Cl2
(1.5 mL) was then added dropwise, and the solution was stirred un-
der reflux for 3 h. The reaction mixture was monitored by TLC until
completion. The MgSO4 was filtered, and the solvent was removed
under reduced pressure. The yellow crude product was purified by
ethyl ether to give FDPIL7 (860 mg, 95% yield) as a yellow solid.
4.2.9. FDPIL5
An argon-purged Schlenk flask was charged with 4-formyl-
N,N,N-trimethyl-benzenemethanaminium
iodide
(305 mg,
1 mmol), (R,Sp)-BPPFNH2 (627 mg, 1.05 mmol), and MgSO4
(500 mg). Next, 3 mL of absolute alcohol were added dropwise,
and the solution was stirred at reflux temperature for 2 h. The reac-
tion mixture was monitored by TLC until completion. The MgSO4
was filtered, and the solvent was removed under reduced pressure.
The yellow crude product was purified by EtOH to give FDPIL5
Mp 203–205 °C. ½a D25
¼ ꢀ369:4 (c 0.6, CH2Cl2). IR (KBr) 1640.6,
ꢂ
1473.3, 1433.3, 1166.0, 1105.7, 565.2. 1H NMR (300 MHz, DMSO-
d6): d 1.44 (d, 3H, J = 6.6 Hz, CHCH3), 3.41–3.60 (m, 2H, Cp-H),
3.89 (s, 3 H, CH3), 4.09–4.14 (m, 2H, Cp-H), 4.23 (s, 1 H, Cp-H),
4.54 (s, 1H, Cp-H), 4.60 (s, 1H, Cp-H), 4.74 (m, 1H, CHMe), 5.73
(s, 2H, Ph-CH2), 6.70–7.81 (m, 25 H, imidazole-H and Ph-H), 8.15
(s, 1 H, N@CH), 9.16 (s, 1 H, NCHN). 13C NMR (100 MHz, DMSO-d6):
d 21.70 (CHMe), 36.41 (NMe), 56.84 (Ph-CH2-N), 63.91 (d, J = 6 Hz,
Cp), 71.27 (Cp), 72.65 (Cp), 73.33 (Cp), 74.33 (Cp), 75.22 (CHMe),
76.14 (d, J = 11 Hz, Cp), 76.70 (d, J = 9 Hz, Cp), 97.04 (d, J = 22 Hz,
Cp), 120.42 (Ph-C), 124.54 (Ph-C), 127.81 (Ph-C), 128.62 (Ph-C),
128.69 (Ph-C), 128.76 (Ph-C), 128.92 (Ph-C), 129.18 (Ph-C), 129.33
(Ph-C), 129.67 (Ph-C), 131.29 (Ph-C), 132.34 (d, J = 19 Hz, Ph-C),
133.19 (d, J = 19 Hz, Ph-C), 133.62 (d, J = 20 Hz, Ph-C), 135.18
(d, J = 21 Hz, Ph-C), 136.89 (d, J = 9 Hz, Ph-C), 137.37 (N–C–N),
138.47 (d, J = 9 Hz, Ph-C), 139.05 (d, J = 9 Hz, Ph-C), 139.41
(d, J = 11 Hz, Ph-C), 148.46 (Ph-C), 158.01 (C@N). 31P NMR
(160 MHz, DMSO-d6): d ꢀ18.93 (s, 1P, PPh2), ꢀ25.50 (s, 1P, PPh2).
MALDI: m:z = 825.7 M+, ESI: m:z = 78.9, 80.9 Mꢀ. Anal. Calcd for
C48H43BrFeN4O2P2: C, 63.66; H, 4.79; N, 6.19. Found: C, 63.64; H,
4.83; N, 6.11.
(831 mg, 94% yield) as
a
yellow solid. Mp 160–162 °C.
½ ꢂ
a 2D5
¼ ꢀ338:6 (c 0.6, CH2Cl2). IR (KBr) 1640.6, 1473.3, 1433.3,
1166.0, 1105.7, 565.2. 1H NMR (300 MHz, CD3OD-d4): d 1.59 (d,
3H, J = 6.6 Hz, CHCH3), 3.00 (s, 1H, Cp-H), 3.11 (s, 9 H, CH3), 3.64
(m, 2H, Cp-H), 4.19 (s, 1 H, Cp-H), 4.27 (s, 2H, Cp-H), 4.52 (s, 2H,
CH2), 4.58 (s, 1H, Cp-H), 4.68 (m, 1H, CHMe), 6.87–7.45 (m, 20 H,
Ph-H), 8.20 (s, 1 H, N@CH).13C NMR (100 MHz, DMSO-d6): d
19.97 (CHMe), 56.33 (NMe3), 56.93 (Ph-C-NMe3), 64.33 (d,
J = 6 Hz, Cp), 71.16 (Cp), 72.78 (d, J = 5 Hz, Cp), 73.18 (d, J = 6 Hz,
Cp), 73.67 (CHMe), 74.89 (d, J = 20 Hz, Cp), 75.92 (Cp), 76.95 (Cp),
96.68 (d, J = 23 Hz, Cp), 119.44 (Ph-C), 127.11 (Ph-C), 127.48 (d,
J = 7 Hz, Ph-C), 127.83 (Ph-C), 128.39 (Ph-C), 127.91 (Ph-C),
128.19 (Ph-C), 128.46 (Ph-C), 129.13 (Ph-C), 129.58 (Ph-C),
132.16 (d, J = 18 Hz, Ph-C), 132.99 (d, J = 19 Hz, Ph-C), 133.31 (d,
J = 20 Hz, Ph-C), 134.99 (d, J = 22 Hz, Ph-C), 136.62 (d, J = 9 Hz,
Ph-C), 137.17 (Ph-C), 138.45 (d, J = 10 Hz, Ph-C), 138.91 (d,
J = 10 Hz, Ph-C), 139.31 (d, J = 10 Hz, Ph-C), 148.08 (C-NMe3),
159.28 (C@N). 31P NMR (160 MHz, DMSO-d6) d ꢀ18.02 (s, 1P,
PPh2), ꢀ25.48 (s, 1P, PPh2). MALDI: m:z = 757.7 M+, ESI:
m:z = 127 Mꢀ. Anal. Calcd for C47H47FeIN2P2: C, 63.82; H, 5.36; N,
3.17. Found: C, 63.69; H, 5.22; N, 3.10.
4.2.12. FDPIL8
An argon-purged Schlenk flask was charged with 3-[(3-formyl-
phenyl)methyl]-1-methyl-1H-imidazolium bromide (281 mg,
1.0 mmol), (R,Sp)-BPPFNH2 (627 mg, 1.05 mmol), and MgSO4
(500 mg). A mixture of absolute alcohol and CH2Cl2 was then
added dropwise, and the solution was stirred at reflux for 3 h.
The reaction mixture was monitored by TLC until completion.
The MgSO4 was filtered, and the solvent was removed under re-
duced pressure. The yellow crude product was purified by ethyl
ether to give FDPIL8 (808 mg, 94% yield) as a light-yellow solid.
4.2.10. FDPIL6
An argon-purged Schlenk flask was charged with 3-[(4-formyl-
phenyl)methyl]-1-methyl-1H-imidazolium bromide (281 mg,
1.0 mmol), (R,Sp)-BPPFNH2 (627 mg, 1.05 mmol), and MgSO4
(500 mg). Absolute alcohol (3 mL) was then added dropwise, and
the solution was stirred at reflux for 3 h. The reaction mixture
was monitored by TLC until completion. The MgSO4 was filtered,
and the solvent was removed under reduced pressure. The yellow
crude product was purified by ethyl ether to give FDPIL6 (817 mg,
Mp 181–184 °C. ½a D25
¼ ꢀ372:9 (c 0.6, CH2Cl2). IR (KBr) 1640.6,
ꢂ
1473.3, 1433.3, 1166.0, 1105.7, 565.2. 1H NMR (300 MHz, DMSO-
d6): d 1.46 (d, 3H, J = 6.6 Hz, CHCH3), 3.48–3.53 (m, 2H, Cp-H),
3.87 (s, 3 H, CH3), 4.12–4.12 (m, 2H, Cp-H), 4.22 (s, 1 H, Cp-H),
95% yield) as a yellow solid. mp 172–176 °C. ½a D25
¼ ꢀ368:7 (c 0.6,
ꢂ
CH2Cl2). IR (KBr) 1640.6, 1473.3, 1433.3, 1166.0, 1105.7, 565.2. 1H

1388
L. Dai et al. / Tetrahedron: Asymmetry 22 (2011) 1379–1389
4.55 (s, 1H, Cp-H), 4.59 (s, 1H, Cp-H), 4.71 (m, 1H, CHMe), 5.33 (s,
2H, Ph-CH2), 6.83–7.73 (m, 26 H, imidazole-H and Ph-H), 8.02 (s, 1
H, N@CH), 9.21 (s, 1 H, NCHN). 13C NMR (100 MHz, DMSO-d6): d
22.08 (CHMe), 36.74 (NMe), 52.00 (Ph-CH2-N), 63.61 (Cp), 71.32
(d, J = 12 Hz, Cp), 72.49 (Cp), 72.23 (Cp), 74.34 (CHMe), 75.14 (d,
J = 19 Hz, Cp), 76.15 (d, J = 10 Hz, Cp), 76.68 (d, J = 9 Hz, Cp),
97.49 (d, J = 23 Hz, Cp), 122.74 (Ph-C), 124.49 (Ph-C), 127.74 (Ph-
C), 127.94 (Ph-C), 128.76 (Ph-C), 128.97 (Ph-C), 129.08 (Ph-C),
129.23 (Ph-C), 129.76 (Ph-C), 130.57 (Ph-C), 132.29 (d, J = 17 Hz,
Ph-C), 133.22 (d, J = 19 Hz, Ph-C), 133.64 (d, J = 20 Hz, Ph-C),
134.86 (Ph-C), 135.29 (d, J = 22 Hz, Ph-C), 136.74 (Ph-C), 137.111
(N–C–N), 138.48 (d, J = 10 Hz, Ph-C), 139.41 (d, J = 12 Hz, Ph-C),
159.16 (C@N). 31P NMR (160 MHz, DMSO-d6): d ꢀ18.94 (s, 1P,
PPh2), ꢀ25.51 (s, 1P, PPh2). MALDI: m:z = 780.7 M+, ESI:
m:z = 78.9, 80.9 Mꢀ. Anal. Calcd for C48H44BrFeN3P2: C, 66.99; H,
5.15; N, 4.88. Found: C, 67.01; H, 5.21; N, 4.80.
CH2Ph), 5.92 (d, 1H, J = 6.8 Hz, CHOBn), 6.89 (dd, 1H, J = 16 Hz
and 7.5 Hz, PhCH@CH), 6.67 (d, 1H, J = 15.5 Hz, PhCH@CH), 7.27–
7.47 (m, 14H, Ph-H). HPLC (Chiralcel OD-H column, 254 nm,
199:1 hexane/isopropanol, flow = 0.2 mL/min), tR = 30.1 min (S),
34.3 min (R).
4.3.5. (S,E)-(3-((4-Chlorobenzyl)oxy)prop-1-ene-1,3-
diyl)dibenzene 2e
Yield = 45%; ½a 2D5
ꢂ
¼ þ22:5 (c 1.6, toluene). 1H NMR (500 MHz,
CDCl3): d 4.59 (d, 1H, J = 12.5 Hz, CH2Ph), 4.57 (d, 1H, J = 12.5 Hz,
CH2Ph), 5.03 (d, 1H, J = 6.5 Hz, CHOBn), 6.37 (dd, 1H, J = 16 Hz
and 7.5 Hz, PhCH@CH), 6.67 (d, 1H, J = 15.5 Hz, PhCH@CH), 7.27–
7.47 (m, 14H, Ph-H). HPLC (Chiralcel OD-H column, 254 nm, 97:3
hexane/isopropanol,
flow = 1.0 mL/min),
tR = 18.9 min
(S),
27.3 min (R).
4.3.6. (S,E)-(3-((4-Bromobenzyl)oxy)prop-1-ene-1,3-
4.3. General procedure for the palladium-catalyzed allylic
etherification
diyl)dibenzene 2f
Yield = 40%; ½a 2D5
ꢂ
¼ þ28:9 (c 1.6, toluene). 1H NMR (500 MHz,
CDCl3): d 4.34 (d, 1H, J = 12.8 Hz, CH2Ph), 4.72 (d, 1H, J = 12.4 Hz,
CH2Ph), 5.67 (d, 1H, J = 7.1 Hz, CHOBn), 6.76 (dd, 1H, J = 18 Hz
and 7.9 Hz, PhCH@CH), 6.94 (d, 1H, J = 15.9 Hz, PhCH@CH), 7.12–
7.97 (m, 14H, Ph-H). HPLC (Chiralcel OJ-H column, 254 nm, 97:3
Chiral ferrocene ligand (25.6
lmol) and Pd(CH3CN)2Cl2 (6.4 mg,
25.6 mol) were dissolved in dry solvent (1 mL) in a dried Schlenk
l
flask under argon and then stirred at room temperature for 1 h. The
solvent was removed under vacuum, then 1a or 1b (0.512 mmol),
Cs2CO3 or another salt (1.536 mmol), three times the equivalent
of the nucleophile (1.536 mmol), and 2 mL of an appropriate sol-
vent were added, and the mixture was stirred for an additional
20 min. The reaction was monitored by TLC. After completion of
the reaction, the mixture was diluted with CH2Cl2 (10 mL). The or-
ganic phase was dried over anhydrous Na2SO4 and then concen-
trated under reduced pressure. The residue was purified by
preparative TLC (petroleum ether/ethyl acetate 30:1) to give the
product.
hexane/isopropanol,
33.3 min (R).
flow = 1.0 mL/min),
tR = 27.9 min
(S),
4.3.7. (S,E)-(3-((4-Methoxybenzyl)oxy)prop-1-ene-1,3-
diyl)dibenzene 2g
Yield = 20%; ½a 2D5
ꢂ
¼ þ2:2 (c 1.0, toluene); 1H NMR (500 MHz,
CDCl3): d 3.85 (s, 3H, OMe), 4.56 (s, 2H, CH2Ph), 5.04 (d, 1H,
J = 7 Hz, CHOBn), 6.39 (dd, 1H, J = 16 Hz and 7 Hz, PhCH@CH),
6.66 (d, 1H, J = 15.5 Hz, PhCH@CH), 6.94–7.48 (m, 14H, Ph-H). HPLC
(Chiralcel OJ-H column, 254 nm, 97:3 hexane/isopropanol,
flow = 1.0 mL/min), tR = 52.0 min (S), 57.1 min (R).
4.3.1. (S,E)-(3-(Benzyloxy)prop-1-ene-1,3-diyl)dibenzene 2a
White solid; yield = 40%; ½a D25
ꢂ
¼ þ12:7 (c 3.3, toluene). 1H NMR
4.3.8. (S,E)-(3-((2-Methoxybenzyl)oxy)prop-1-ene-1,3-
(500 MHz, CDCl3): d 4.64 (s, 2H, CH2Ph), 5.08 (d, 1H, J = 7 Hz,
CHOBn), 6.42 (dd, 1H, J = 16 Hz and 6.5 Hz, PhCH@CH), 6.69 (d,
1H, J = 16 Hz, PhCH@CH), 7.28 (t, 1H, J = 7.5 Hz, Ph-H), 7.37–7.50
(m, 14H, Ph-H). HPLC (Chiralcel OJ-H column, 254 nm, 97:3 hex-
ane/isopropanol, flow = 1.0 mL/min), tR = 15.48 min [(S)-enantio-
mer], tR = 18.50 min [(R)-enantiomer].
diyl)dibenzene 2h
Yield = 30%; ½a 2D5
ꢂ
¼ þ20:5 (c 1.0, toluene). 1H NMR (500 MHz,
CDCl3): d 4.23 (s, 3H, OMe), 4.84 (s, 2H, CH2Ph), 5.83 (d, 1H,
J = 8.1 Hz, CHOBn), 5.59 (dd, 1H, J = 16.5 Hz and 8.5 Hz, PhCH@CH),
6.95 (d, 1H, J = 16 Hz, PhCH@CH), 7.01–7.98 (m, 14H, Ph-H). HPLC
(Chiralcel OJ-H column, 254 nm, 97:3 hexane/isopropanol,
flow = 1.0 mL/min), tR = 50.7 min (S), 56.0 min (R).
4.3.2. (S,E)-(3-((4-Fluorobenzyl)oxy)prop-1-ene-1,3-
diyl)dibenzene 2b
4.3.9. (S,E)-(3-((3-Methoxybenzyl)oxy)prop-1-ene-1,3-
Yield = 20%; ½a 2D5
ꢂ
¼ þ17:3 (c 0.7, toluene). 1H NMR (500 MHz,
diyl)dibenzene 2i
CDCl3): d 4.57 (dd, 2H, J = 18.5 Hz and 6.5 Hz, CH2Ph), 5.03 (d, 1H,
J = 7.5 Hz, CHOBn), 6.37 (dd, 1H, J = 16 Hz and 7 Hz, PhCH@CH),
6.66 (d, 1H, J = 16 Hz, PhCH@CH), 7.07–7.46 (m, 14H, Ph-H). HPLC
(Chiralcel OD-H column, 254 nm, 99:1 hexane/isopropanol,
flow = 0.2 mL/min), tR = 30.7 min (S), 39.1 min (R).
Yield = 37%; ½a 2D5
ꢂ
¼ þ18:5 (c 1.0, toluene). 1H NMR (500 MHz,
CDCl3): d 3.81 (s, 3H, OMe), 4.58 (s, 2H, CH2Ph), 5.03 (d, 1H,
J = 7 Hz, CHOBn), 6.36 (dd, 1H, J = 15.5 Hz and 6.5 Hz, PhCH@CH),
6.65 (d, 1H, J = 16 Hz, PhCH@CH), 6.85–7.45 (m, 14H, Ph-H). HPLC
(Chiralcel OJ-H column, 254 nm, 97:3 hexane/isopropanol,
flow = 1.0 mL/min), tR = 51.9 min (S), 56.1 min (R).
4.3.3. (S,E)-(3-((2-Fluorobenzyl)oxy)prop-1-ene-1,3-
diyl)dibenzene 2c
4.3.10. (S,E)-(3-((4-Methylbenzyl)oxy)prop-1-ene-1,3-
Yield = 23%; ½a 2D5
ꢂ
¼ þ21:3 (c 0.7, toluene). 1H NMR (500 MHz,
diyl)dibenzene 2j
CDCl3): d 4.67 (d, 1H, J = 12.8 Hz, CH2Ph), 4.92 (d, 1H, J = 12.8 Hz,
CH2Ph), 5.47 (d, 1H, J = 6.9 Hz, CHOBn), 6.72 (dd, 1H, J = 16 Hz
and 7.5 Hz, PhCH@CH), 6.67 (d, 1H, J = 15.5 Hz, PhCH@CH), 7.14–
7.89 (m, 14H, Ph-H). HPLC (Chiralcel OD-H column, 254 nm,
199:1 hexane/isopropanol, flow = 0.1 mL/min), tR = 53.6 min (S),
59.8 min (R).
Yield = 23%; ½a 2D5
ꢂ
¼ þ17:5 (c 1.2, toluene). 1H NMR (500 MHz,
CDCl3): d 2.44 (s, 3H, CH3), 4.63 (s, 2H, CH2Ph), 5.09 (d, 1H,
J = 7.5 Hz, CHOBn), 6.43 (dd, 1H, J = 16.5 Hz and 7.5 Hz, PhCH@CH),
6.71 (d, 1H, J = 16 Hz, PhCH@CH), 7.25–7.52 (m, 14H, Ph-H). HPLC
(Chiralcel OJ-H column, 254 nm, 97:3 hexane/isopropanol,
flow = 1.0 mL/min), tR = 16.0 min (S), 27.3 min (R).
4.3.4. (S,E)-(3-((3-Fluorobenzyl)oxy)prop-1-ene-1,3-
4.3.11. (S,E)-(3-((2-Methylbenzyl)oxy)prop-1-ene-1,3-
diyl)dibenzene 2d
diyl)dibenzene 2k
Yield = 33%; ½a 2D5
ꢂ
¼ þ25:1 (c 0.7, toluene). 1H NMR (500 MHz,
Yield = 31%; ½a 2D5
ꢂ
¼ þ7:5 (c 1.2, toluene). 1H NMR (500 MHz,
CDCl3): d 4.98 (d, 1H, J = 12.8 Hz, CH2Ph), 4.66 (d, 1H, J = 11.9 Hz,
CDCl3): d 2.38 (s, 3H, CH3), 4.60 (d, 1H, J = 12 Hz, CH2Ph), 4.64

L. Dai et al. / Tetrahedron: Asymmetry 22 (2011) 1379–1389
1389
(d, 1H, J = 12 Hz, CH2Ph), 5.07 (d, 1H, J = 7.0 Hz, CHOBn), 6.41 (dd,
References
1H, J = 16 Hz and 7 Hz, PhCH@CH), 6.70 (d, 1H, J = 15.5 Hz,
PhCH@CH), 7.22–7.50 (m, 14H, Ph-H). HPLC (Chiralpak AD-H col-
umn, 254 nm, 98:2 hexane/isopropanol, flow = 1.0 mL/min),
tR = 12.7 min (S), 14.9 min (R).
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4.3.12. (S,E)-2-(((1,3-Diphenylallyl)oxy)methyl)furan 2l
Yield = 23%; ½a 2D5
ꢂ
¼ þ5:9 (c 1.0, toluene). 1H NMR (500 MHz,
CDCl3): d 4.53 (s, 2H, CH2Fu), 5.05 (d, 1H, J = 7 Hz, CHO), 6.37–
6.33 (m, 3H), 6.64 (d, 1H, J = 15.5 Hz, PhCH@CH), 7.25–7.45 (m,
11H, Ph-H). HPLC (Chiralcel OJ-H column, 254 nm, 90:10 hexane/
isopropanol, flow = 1.0 mL/min), tR = 53.9 min (S), 58.7 min (R).
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4.3.13. (S,E)-(3-Phenoxyprop-1-ene-1,3-diyl)dibenzene 2m
Yield = 33%; ½a 2D5
ꢂ
¼ þ15:9 (c 1.0, toluene). 1H NMR (500 MHz,
CDCl3): d 2.38 (s, 3H, CH3), 4.60 (d, 1H, J = 12 Hz, CH2Ph), 4.64 (d,
1H, J = 12 Hz, CH2Ph), 5.07 (d, 1H, J = 7.0 Hz, CHOBn), 6.41 (dd,
1H, J = 16 Hz and 7 Hz, PhCH@CH), 6.70 (d, 1H, J = 15.5 Hz,
PhCH@CH), 7.22–7.50 (m, 15H, Ph-H). HPLC (Chiralcel OJ-H col-
umn, 254 nm, 97:3 hexane/isopropanol, flow = 1.0 mL/min),
tR = 33.5 min (S), 39.2 min (R).
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Yield = 36%; ½a 2D5
ꢂ
¼ þ15:8 (c 1.0, toluene). 1H NMR (500 MHz,
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CDCl3): d 5.77 (d, 1H, J = 6 Hz, CHOPh), 6.44 (dd, 1H, J = 16 Hz and
6.5 Hz, PhCH@CH), 6.68 (d, 1H, J = 16 Hz, PhCH@CH), 6.91–7.46 (m,
14H, Ph-H). HPLC (Chiralcel OJ-H column, 254 nm, 97:3 hexane/iso-
propanol, flow = 1.0 mL/min), tR = 22.9 min (S), 26.5 min (R).
4.4. NMR study of the FDPIL3-b palladium complexes
1H NMR (300 MHz, DMSO-d6): d 1.25 (d, 3H, J = 6.6 Hz, CHCH3),
2.10 (s, 6H, CH3CN), 3.56–3.63 (m, 2H, Cp-H), 3.94 (s, 9 H, CH3),
4.11–4.14 (m, 2H, Cp-H), 4.31 (s, 1 H, Cp-H), 4.42 (s, 1H, Cp-H),
4.47 (s, 1H, Cp-H), 5.04 (m, 1H, CHMe), 6.60–7.98 (m, 20 H, Ph-H),
8.41 (s, 1 H, N@CH). 13C NMR (100 MHz, DMSO-d6): d 1.86 (CH3CN),
29.63 (CHMe), 57.81 (NMe3), 71.26 (Cp-C), 73.81 (Cp-C), 76.68 (Cp-
C), 77.00 (Cp-C), 77.20 (Cp-C), 77.32 (Cp-C), 116.31 (CH3CN),
120.03 (Ph-C), 128.09 (Ph-C), 128.80 (d, J = 6 Hz, Ph-C), 130.23 (Ph-
C), 131.96 (Ph-C), 132.59 (Ph-C), 134.49 (Ph-C), 136.91 (Ph-C),
137.81 (Ph-C), 148.05 (C-NMe3). 31P NMR (160 MHz, CDCl3): d
30.20 (d, 1P, J = 23 Hz, PPh2), 34.48 (d, 1P, J = 23 Hz, PPh2).
Acknowledgments
The Major Projects Cultivating Special Program in Technology
Innovation Program (Grant No. 2011CX01008), The National Tech-
nological Project of the Manufacture and Innovation of Key New
Drugs (2009ZX09103-143) and the Ph.D. candidate in the Chinese
Academy of Sciences, Mr. William A. Jefferson.
14. Casey, M.; Leonard, J.; Lygo, B. Advance Practical Organic Chemistry; Blackie:
New York, 1990.