Carbonyl allylation of aldehydes catalyzed by a silica-supported poly-γ-diphenylarsinopropylsiloxane palladium(0) complex

Article abstract of DOI:10.1016/j.jorganchem.2004.04.031

A silica-supported poly-γ-diphenylarsinopropylsiloxane palladium (0) complex has been prepared from γ-chloropropyltriethoxysilane via immobilization on fumed silica, followed by reacting with potassium diphenylarsenide and palladium chloride, and then the reduction with hydrazine hydrate. The palladium(0) complex has been found to catalyze the allylation of aldehydes via the formation of π-allylpalladium complexes, using allylic chlorides as allylating agent and SnCl₂ as reducing agent. This polymeric palladium complex can be recovered and reused.

Full text of DOI:10.1016/j.jorganchem.2004.04.031

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Journal of Organometallic Chemistry 689 (2004) 2436–2440
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Carbonyl allylation of aldehydes catalyzed by a silica-supported
poly-c-diphenylarsinopropylsiloxane palladium(0) complex
a,
a
b
a
Mingzhong Cai *, Yizheng Huang , Hong Zhao , Rongli Zhang
a
Department of Chemistry, Jiangxi Normal University, Nanchang 330027, PR China
b
Department of Pharmacy, Guangdong Pharmaceutical College, Guangzhou 510240, PR China
Received 2 December 2003; accepted 21 April 2004
Abstract
A silica-supported poly-c-diphenylarsinopropylsiloxane palladium(0) complex has been prepared from c-chloropropyltriethox-
ysilane via immobilization on fumed silica, followed by reacting with potassium diphenylarsenide and palladium chloride, and then
the reduction with hydrazine hydrate. The palladium(0) complex has been found to catalyze the allylation of aldehydes via the
formation of p-allylpalladium complexes, using allylic chlorides as allylating agent and SnCl2 as reducing agent. This polymeric
palladium complex can be recovered and reused.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Supported palladium catalyst; Arsine palladium(0) complex; Carbonyl allylation; p-Allylpalladium complex; Aldehyde
1. Introduction
plexes such as Pd(PPh3)4, Pd(PPh3)2Cl2 and Pd(PhCN)2
Cl2 are usually used for formation of p-allylpalladium
complexes. The amount of palladium catalyst used is
about 2 mol% of reactant and it is difficult to recover
them from the products. Easy recovery and reuse of
the catalytic species make the reaction very attractive
commercially.
Nucleophilic substitution of p-allylpalladium com-
plexes has provided a new method for carbon–carbon
bond formation and has been applied into the synthesis
of wide range of natural products and other complex
organic molecules [1–4]. If the p-allylpalladium com-
plexes were used not only as electrophiles but also as
nucleophiles, the chemistry of p-allylpalladium com-
plexes could be further developed in organic synthesis.
The utilization of p-allylpalladium complexes as nucle-
ophiles has been exemplified by the transformation of
allylic esters [5–7] or allylic alcohols [8] or allylic chlo-
rides [9] to allylic metal compounds with palladium(0)
catalyst and low-valent metals, which have been applied
to carbonyl allylation. Some other carbonyl allylation
reactions of aldehydes with different mechanisms could
afford the same adduct [10]. Masuyama et al. [11,12]
reported that stannous chloride is more effective as a
reducing agent than other low-valent metals in palladi-
um-catalyzed carbonyl allylation by allylic esters.
However, in most cases, homogeneous palladium com-
Polymer supported transition metal complexes hav-
ing high activity and selectivity are currently attracting
great interest because they combine the advantages of
homogeneous and heterogeneous catalyzed processes.
Polymer-supported palladium catalysts have success-
fully been used for a variety of organic reactions [13–16].
However, polymer-supported palladium catalysts for
carbonyl allylation has received less attention. Recently,
we have found that the silica-supported poly-c-cya-
nopropylsiloxane palladium complex (abbreviated as
‘Si’–CN–Pd) is an efficient catalyst for carbonyl allyla-
tion of aldehydes and ketones with allyl chloride and
allyl acetate, but the activity of the catalyst decreased
gradually with repeated use [17]. Study of new types of
polymer-bound palladium catalysts which might be
suitable for carbonyl allylation of aldehydes or ketones
has theoretical and practical significance. However, little
attention has so far been given to arsenic transition
* Corresponding author. Fax: +86-791-8517500.
E-mail address: caimz618@sina.com (M. Cai).
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.04.031

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M. Cai et al. / Journal of Organometallic Chemistry 689 (2004) 2436–2440
2437
metal complexes [18,19]. To our knowledge, no
allylation of aldehydes and ketones catalyzed by an ar-
senic palladium complex has been reported. In this pa-
per we wish to report the synthesis of silica-supported
poly-c-diphenylarsinopropylsiloxane palladium(0) com-
plex (abbreviated as ‘Si’–As–Pd(0)) and its catalytic
properties in the carbonyl allylation of aldehydes and
ketones with allylic chlorides.
strongly on the nature of the ligands. Consequently, it is
impossible to identify the reduced complex as a zero-
valent one on the basis of its Pd3d5=2 binding energy
only. However, the binding energy of Cl(2p) in the ‘Si’–
As–Pd(0) cannot be detected, the shift (lower) of Pd3d5=2
binding energy, together with the black color suggest
that the reduction of the starting palladium(II) complex
to the lower valent state has taken place. The ‘Si’–As–
Pd(0) has the formula (SiO2)24(SiCH2CH2CH2As
(C6H5)2)4Pd according to the elemental analyses, which
suggests that the probable local structure of the ‘Si’–As–
Pd(0) is below (Scheme 2).
2. Results and discussion
It is well known that zero-valent palladium complexes
show unique reactivity in various organic reactions.
However, it is very difficult to use the homogeneous
Pd(0) complexes as practical catalysts because of their
instability to air and moisture. A silica-supported poly-
c-diphenylarsinopropylsiloxane palladium(0) complex
was conveniently prepared from c-chloropropyltrieth-
oxysilane via immobilization on fumed silica, followed
by reacting with potassium diphenylarsenide in THF
and palladium chloride in acetone, and then the reduc-
tion with hydrazine hydrate in ethanol (Scheme 1).
The X-ray photoelectron spectroscopy (XPS) has
been used to characterize this polymeric palladium cat-
alyst. Table 1 shows the XPS data for ‘Si’–As–Pd(0),
‘Si’–As–Pd(II), ‘Si’–As and PdCl2. It can be seen that
the binding energies of Si(2p) and O(1s) of ‘Si’–As–
Pd(II) are similar to those of ‘Si’–As, and the binding
energy of Cl(2p) of ‘Si’–As–Pd(II) is similar to that of
PdCl2. However the difference of As(3d) binding ener-
gies between ‘Si’–As–Pd(II) and ‘Si’–As is 0.9 eV. The
difference of Pd3d5=2 binding energies between ‘Si’–As–
Pd(II) and PdCl2 is 1.6 eV. These results show that a
coordination bond between As and Pd is formed. The
binding energy (335.7 eV) of Pd3d5=2 of ‘Si’–As–Pd(0) is
lower than the binding energy (336.7 eV) of Pd3d5=2 of
‘Si’–As–Pd(II). The Pd3d5=2 binding energy depends
In order to test the catalytic activity of the new
polymer-bound palladium(0) catalyst (‘Si’–As–Pd(0)),
the carbonyl allylation of aldehydes with allylic chlo-
rides was studied (Scheme 3). The reactions were carried
out under conditions similar to those used in the cor-
responding homogeneous reactions. The results are
summarized in Table 2.
The allylation of benzaldehyde with allyl chloride was
carried out at 25 °C in the presence of SnCl2 using DMF
as solvent. When 2.0 mol% palladium catalyst (‘Si’–As–
Pd(0)) was used, the allylation of benzaldehyde could be
accomplished within 48 h and 1-phenylbut-3-en-1-ol was
obtained in 85% yield. When 2.0 mol% PdCl2(PhCN)2
was used, 1-phenylbut-3-en-1-ol was obtained in 80%
yield under same conditions. This polymeric palladium
catalyst not only has higher catalytic activity in the al-
lylation of benzaldehyde than PdCl2(PhCN)2, but also
can be recovered by simple filtration. The activity of the
recovered catalyst was tested for two recycles and it was
found that the yield of 1-phenylbut-3-en-1-ol decreased
by only 2% and 3% after each recycle, respectively.
The reaction is suitable for a variety of functional
groups on the aromatic aldehydes; both strongly elec-
tron donating and withdrawing substituents can be
present. The allylation of various aromatic aldehydes
with allyl chloride has been achieved with good to high
O
H2O, toluene
(EtO)3SiCH2CH2CH2Cl + SiO2
)
O
SiCH2CH2CH2Cl
O
SiO2
( 'Si'-Cl )
reflux
O
O
Ph2AsK
THF
PdCl2
acetone
)
]
SiCH2CH2CH2AsPh2
O
)
SiO2
O
SiCH2CH2CH2AsPh2
2 PdCl2
SiO2
O
O
(II) )
( 'Si'-As-Pd
( 'Si'-As )
O
.
H2NNH2 H2O
]
)
SiCH2CH2CH2AsPh2
4 Pd
SiO2
O
EtOH
O
(
) )
( 'Si'-As-Pd
0
Scheme 1.

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2438
M. Cai et al. / Journal of Organometallic Chemistry 689 (2004) 2436–2440
Table 1
XPS data for ‘Si’–As–Pd(0), ‘Si’–As–Pd(II), ‘Si’–As and PdCl2 (in eV)a
The allylation of ketones with allylic chlorides did not
occur at all under same reaction conditions. Thus,
chemoselective addition to an aldehyde can be realized
in the presence of a ketone by using ‘Si’–As–Pd(0) as
catalyst.
A plausible mechanism is shown in Scheme 4. Oxida-
tive addition of allylic chlorides 1 to the ‘Si’–As–Pd(0)
gives the polymer-bound g3-allyl(chloro)palladium
complexes A, and the reduction of A with SnCl2 produces
the allylic trichlorotins B and regenerates the ‘Si’–As–
Pd(0). Nucleophilic addition of the allylic trichlorotins B
to aldehydes 2 affords homoallylic alcohols 3.
IR spectra were obtained using a Perkin–Elmer 683
instrument. 1H NMR spectra were recorded on a JEOL
FX-90Q (90 MHz) or a Bruker AC-P300 (300 MHz)
spectrometer with TMS as an internal standard in
CDCl3 as solvent. Microanalyses were obtained using a
Perkin–Elmer 240 elemental analyzer. DMF was dis-
tilled before use, other reagents were used as received
without further purification.
Sample
Pd3d5=2 As3d
Si2p
O1s
Cl2p
‘Si’–As–Pd(0)
‘Si’–As–Pd(II)
‘Si’–As
335.7
336.7
42.6
42.5
41.6
103.1
103.1
103.0
532.3
532.4
532.3
199.1
199.2
PdCl2
338.3
a The binding energies are referenced to C1s (284.6 eV), and the en-
ergy differences were determined with an accuracy of 0.2 eV.
O
Si
O
O
O
O
CH2CH2CH2AsPh2
(SiO2)12
Ph2AsCH2CH2CH2Si
(SiO2)12
O
O
O
Ph2AsCH2CH2CH2Si
O
Pd
SiCH2CH2CH2AsPh2
O
Scheme 2.
R1
R1
OH
O
Cat.'Si'-As-Pd(0)
+
Cl
R
H
SnCl2, DMF, 25-40˚C
R
2.1. Preparation of silica-supported poly-c-diph-
enylarsinopropylsiloxane (‘Si’–As)
3
1
2
Scheme 3.
A mixture of fumed silica (6.0 g) and c-chloro-
propyltriethoxysilane (5.0 g) in toluene (140 ml) was
stirred at 120 °C for 24 h. Distilled water (20 ml) and
10% hydrochloric acid (0.2 ml) were added and the
mixture was refluxed for another 48 h. After being
cooled to room temperature, the mixture was filtered,
washed with distilled water (4 ꢀ 50 ml) and dried at
220 °C in vacuo for 5 h. The resulting white powder
was washed with acetone (3 ꢀ 50 ml), followed by drying
to afford 7.2 g of silica-supported poly-c-chloro-
propylsiloxane (‘Si’–Cl). The carbon, hydrogen and
chlorine content was 6.45, 13.10 and 2.08 mmol/g, re-
spectively. The ‘Si’–Cl has the formula (SiO2)24(SiCH2
CH2CH2Cl)4 according to the elemental analyses.
Table 2
Carbonyl allylation of aldehydes catalyzed by ‘Si’–As–Pd(0)
Entry
R
R1
Temperature Product Yield
(%)a
(°C)
1
2
Ph
Ph
H
25
3a
3b
3c
3d
3e
3f
85
81
87
89
57
60
82
86
84
85
82
81
78
80
76
CH3 40
25
CH3 40
25
CH3 40
3
4-ClC6H4
4-ClC6H4
4-O2NC6H4
4-O2NC6H4
4-CH3OC6H4
3,4-CH2O2C6H3
3,4-CH2O2C6H3
2-HOC6H4
2-HOC6H4
n-C3H7
H
4
5
H
6
7
H
H
25
25
3g
3h
3i
8
9
CH3 40
25
CH3 40
25
CH3 40
25
CH3 40
10
11
12
13
14
15
H
3j
A mixture of Ph3As (2.90 g, 9.5 mmol) and potassium
(0.74 g, 19 mmol) in THF (50 ml) was stirred under
nitrogen at 60 °C for 16 h. After being cooled to room
temperature, the mixture was treated with t-BuCl (0.88
g, 9.5 mmol) for 1 h to give a brown solution. Into the
3k
3l
H
n-C3H7
n-C6H13
n-C6H13
3m
3n
3o
H
Reactions were carried out with 1 mmol of aldehyde, 2 mmol of
allylic chloride, 1.5 mmol of SnCl2, 0.02 mmol of palladium catalyst in
3 ml of DMF for 48 h.
a Yield of isolated product 3 based on the aldehyde.
'Si'
As
R1
OH
R1
RCHO (2)
Pd(0)
SnCl3
R
R1
yields. The allylation of aliphatic aldehydes with allyl
chloride also proceeded smoothly in the presence of ‘Si’–
As–Pd(0) at 25 °C and the corresponding homoallylic
alcohols were obtained in good yields. The allylation of
aldehydes with methallyl chloride was very slow at 25 °C
and only trace amounts of products was formed after 48
h. However, the allylation reactions proceeded very
smoothly at 40 °C and the corresponding homoallylic
alcohols were obtained in good to high yields after 48 h.
B
3
Cl
R1
Pd
1
SnCl2
'Si'-As
Cl
A
Scheme 4. Proposed mechanism for the carbonyl allylation of alde-
hydes catalysed by ‘Si’–As–Pd(0).

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M. Cai et al. / Journal of Organometallic Chemistry 689 (2004) 2436–2440
2439
resulting solution was added ‘Si’–Cl (4.10 g) and the
mixture was stirred at room temperature for 2 h and
then refluxed for 24 h. The mixture was cooled to room
temperature and treated with t-BuCl (2 ml) for 2 h. The
mixture was filtered and washed with 95% ethanol
(4 ꢀ 30 ml), distilled water (5 ꢀ 30 ml), acetone (3 ꢀ 30
ml) and then dried under vacuum to give 3.98 g of silica-
supported poly-c-diphenylarsinopropylsiloxane (‘Si’–
As). The carbon, hydrogen and arsenic content was
23.86, 25.75 and 1.58 mmol/g, respectively. The ‘Si’–As
has the formula (SiO2)22(SiCH2CH2CH2As(C6H5)2)4
according to the elemental analyses.
5H), 5.88–5.50 (m, 1H), 5.14–4.89 (m, 2H), 4.66 (t,
J ¼ 6:8 Hz, 1H), 2.51–2.26 (m, 2H), 2.17 (br, 1H).
Anal. Found: C, 80.89; H, 7.90. C10H12O Calc. C,
81.08; H, 8.11%.
2.3.2. 1-Phenyl-3-methylbut-3-en-1-ol (3b)
IR (film): m (cmꢁ1) 3399, 3073, 3030, 2936, 1647, 1603,
1493, 1453, 1375, 1054, 891, 756, 699. 1H NMR: d 7.40–
7.24 (m, 5H), 4.94–4.86 (m, 2H), 4.82 (t, J ¼ 6:8 Hz,
1H), 2.43 (d, J ¼ 6:8 Hz, 2H), 2.15 (br, 1H), 1.81 (s, 3H).
Anal. Found: C, 81.22; H, 8.48. C11H14O Calc. C, 81.48;
H, 8.64%.
2.2. Preparation of silica-supported poly-c-diph-
enylarsinopropylsiloxane palladium(0) complex (‘Si’–
As–Pd(0))
2.3.3. 1-(4-Chlorophenyl)but-3-en-1-ol (3c)
IR (film): m (cmꢁ1) 3387, 3078, 3028, 2907, 1641, 1597,
1492, 1411, 1051, 919, 830. H NMR: d 7.28 (s, 4H),
1
5.90–5.56 (m, 1H), 5.17–4.95 (m, 2H), 4.71 (t, J ¼ 6:8
Hz, 1H), 2.53–2.28 (m, 2H), 2.16 (br, 1H). Anal. Found:
C, 65.51; H, 5.83. C10H11OCl Calc. C, 65.75; H, 6.03%.
To a solution of PdCl2 (0.156 g) in acetone (40 ml)
was added ‘Si’–As (2.02 g). The mixture was refluxed
under nitrogen for 48 h. The product was allowed to
cool, then filtered. The brown solid was washed with
distilled water (3 ꢀ 30 ml) and acetone (3 ꢀ 20 ml), then
stirred with hydrazine hydrate (1.5 g) and EtOH (20 ml)
at 30 °C under nitrogen for 2 h. The resulting product
was filtered, washed with EtOH (4 ꢀ 30 ml) and Et2O
(2 ꢀ 30 ml) and dried under vacuum to give 1.96 g of the
black polymeric palladium(0) complex (‘Si’–As–Pd(0)).
The carbon, hydrogen, arsenic and palladium content
was 21.42 mmol/g, 23.24 mmol/g, 1.40 mmol/g and 0.39
mmol/g, respectively. The ‘Si’–As–Pd(0) has the formula
(SiO2)24(SiCH2CH2CH2As(C6H5)2)4Pd according to the
elemental analyses.
2.3.4. 1-(4-Chlorophenyl)-3-methylbut-3-en-1-ol (3d)
IR (film): m (cmꢁ1) 3400, 3076, 3028, 2971, 2936, 1647,
1598, 1491, 1444, 1376, 1064, 1014, 894, 830. H NMR:
1
d 7.28 (s, 4H), 4.94–4.85 (m, 2H), 4.79 (t, J ¼ 6:8 Hz,
1H), 2.38 (d, J ¼ 7:2 Hz, 2H), 2.16 (br, 1H), 1.80 (s, 3H).
Anal. Found: C, 67.25; H, 6.56. C11H13OCl Calc. C,
67.18; H, 6.62%.
2.3.5. 1-(4-Nitrophenyl)but-3-en-1-ol (3e)
IR (film): m (cmꢁ1) 3398, 3074, 3025, 2958, 1650, 1602,
1
1525, 1493, 1346, 845. H NMR: d 8.21 (d, J ¼ 8:8 Hz,
2H), 7.53 (d, J ¼ 8:8 Hz, 2H), 5.82–5.74 (m, 1H), 5.22–
5.16 (m, 2H), 4.87 (t, J ¼ 5:6 Hz, 1H), 2.59–2.44 (m,
2H), 2.23 (br, 1H). Anal. Found: C, 61.89; H, 5.52; N,
7.08. C10H11NO3 Calc. C, 62.18; H, 5.70; N, 7.25%.
2.3. General procedure for the allylation of aldehydes with
allylic chlorides
2.3.6. 1-(4-Nitrophenyl)-3-methylbut-3-en-1-ol (3f)
IR (film): m (cmꢁ1) 3400, 3075, 3027, 2972, 1648, 1601,
To a mixture of SnCl2 (1.5 mmol), aldehyde (1 mmol),
and allylic chloride (2 mmol) in DMF (3 ml) was added
‘Si’–As–Pd(0) (50 mg, 0.02 mmol Pd) at the temperature
indicated in Table 2 under a nitrogen atmosphere. After
being stirred for 48 h, the mixture was filtered and the
catalyst was washed with DMF (2 ꢀ 10 ml), diethyl ether
(2 ꢀ 10 ml) and reused in the next run. The filtrate was
diluted with 120 ml of a mixed solvent (diethyl ether:di-
chloromethane ¼ 2:1) and washed successively with
aqueous 10% HCl solution (2 ꢀ 10 ml), aqueous
NaHCO3 solution (10 ml), and water (3 ꢀ 10 ml). The
extracts were dried over anhydrous MgSO4. After re-
moval of the solvent under reduced pressure, the residue
was purified by preparative TLC on silica gel (light pe-
troleum:ethyl acetate ¼ 7:1) to afford a colorless oil.
1
1524, 1492, 1345, 846. H NMR: d 8.22 (d, J ¼ 8:5 Hz,
2H), 7.57 (d, J ¼ 8:5 Hz, 2H), 5.00–4.88 (m, 3H), 2.44–
2.31 (m, 3H), 1.83 (s, 3H). Anal. Found: C, 63.51; H,
6.02; N, 6.53. C11H13NO3 Calc. C, 63.77; H, 6.28; N,
6.76%.
2.3.7. 1-(4-Methoxyphenyl)but-3-en-1-ol (3g)
IR (film): m (cmꢁ1) 3386, 3072, 3019, 2930, 2850, 1640,
1600, 1500, 1450, 1380, 1240, 1175, 1030, 830. 1H NMR:
d 7.15 (d, J ¼ 8:8 Hz, 2H), 6.79 (d, J ¼ 8:8 Hz, 2H),
5.89–5.49 (m, 1H), 5.13–4.82 (m, 2H), 4.69 (t, J ¼ 6:8
Hz, 1H), 3.78 (s, 3H), 2.50–2.24 (m, 2H), 2.09 (br, 1H).
Anal. Found: C, 74.27; H, 7.78. C11H14O2 Calc. C,
74.16; H, 7.87%.
2.3.1. 1-Phenylbut-3-en-1-ol (3a)
IR (film): m (cmꢁ1) 3390, 3075, 3030, 2907, 1641,
1603, 1493, 1020, 750, 690. H NMR: d 7.36–6.95 (m,
2.3.8. 1-(3,4-Methylenedioxyphenyl)but-3-en-1-ol (3h)
IR (film): m (cmꢁ1) 3360, 3070, 3024, 2880, 1640, 1600,
1490, 1440, 1240, 1030, 990, 870. H NMR: d 6.88 (d,
1
1