Butoxycarbonylation of aryl halides catalyzed by a silica-supported poly[3-(2-cyanoethylsulfanyl)propylsiloxane palladium] complex

Article abstract of DOI:10.1039/a702085f

Aryl bromides and iodides react with carbon monoxide and n-butyl alcohol at 100°C and atmospheric pressure in the presence of tri-n-butylamine and a catalytic amount of a silica-supported sulfur palladium complex to form esters in moderate to good yields.

Full text of DOI:10.1039/a702085f

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Butoxycarbonylation of aryl halides catalyzed by a silica-supported
poly[3-(2-cyanoethylsulfanyl)propylsiloxane palladium] complex
a
b
,a
Ming-Zhong Cai, Cai-Sheng Song and Xian Huang*
a
Department of Chemistry, Hangzhou University, Hangzhou, 310028, PR China
Department of Chemistry, Jiangxi Normal University, Nanchang, 330027, PR China
b
a
Aryl bromides and iodides react with carbon monoxide and
n-butyl alcohol at 100 ЊC and atmospheric pressure in the
presence of tri-n-butylamine and a catalytic amount of a
silica-supported sulfur palladium complex to form esters in
moderate to good yields.
Table 1 Butoxycarbonylation of aryl halides
b
Entry R᎐X
t/h
Product (yield, %)
n
1
2
3
4
5
6
7
8
9
C H I
25
30
25
25
25
25
40
40
40
30
72
C H CO Bu (88)
4-CH OC H CO Bu (82)
4-CH C H CO Bu (87)
4-ClC
6
5
6
5
2
n
4-CH OC H I
3
6
4
3
6
4
2
n
4-CH C H I
3
6
4
3
6
4
2
n
The carbonylation of aryl halides in the presence of palladium
catalysts is a very versatile reaction and an important synthetic
route because it has the advantage of proceeding smoothly
under low pressures of carbon monoxide. For example, the syn-
4-ClC
6
H
4
I
6
H
4
CO Bu (91)
2
n
4-CH O CC H I
4-CH O CC H CO Bu (90)
3 2 6 4 2
n
3
2
6
4
4-NO C H I
4-NO C H CO Bu (84)
2 6 4 2
n
2
6
4
c
4-ClC H Br
4-ClC H CO Bu (56)
6 4 2
n
6
4
c
4-CH O CC H Br
4-CH O CC H CO Bu (54)
3 2 6 4 2
n
3
2
6
4
c
1
,2
3
4
5
theses of carboxylic acids, esters, acid fluorides, amides and
4-NO C H Br
4-NO C H CO Bu (45)
2
6
4
2
6
4
2
6
n
aldehydes have been reported to be readily achieved with an
10
11
C H CH Br
C H CH CO Bu (27)
1-C10
6
5
2
6
5
2
2
c
n
atmospheric pressure of CO in good to high yields. However,
in most cases, homogeneous catalysts such as Pd(OAc)2,
Pd(PPh ) Cl are used and it is difficult to recover them from
1-C10
H
7
Br
H
7
CO Bu (34)
2
a
Reactions were carried out at 100 ЊC with 1 atm of CO, 3 mmol of aryl
halide, 0.04 mmol of palladium catalyst, and 3.5 mmol of tri-n-
butylamine in 2 ml of n-butyl alcohol. Yields are of isolated, pure
3
2
2
the products. Polymer-supported metal complexes are currently
attracting great interest because they combine the advantages
of homogeneous and heterogeneous catalyzed processes. Reddy
b
c
products. 0.06 mmol PPh was added.
3
7
et al. reported that a polymer-anchored phosphine palladium
that a coordination bond between S and Pd is formed. In this
paper we report its catalytic properties in the butoxycarbonyl-
ation of aryl halides with carbon monoxide in n-butyl alcohol
at 1 atm pressure (Scheme 2).
complex with a P :Pd ratio of 0.895 catalyzed ethoxycarbonyl-
ation of organic halides in ethanol, but the activity of the
catalyst was moderate and decreased gradually with repeated
use. It is known that catalysts containing phosphine ligands
8
are unstable. Furthermore, the procedure for preparing the
i
n
RCO2Bun
RX
+
CO
+
Bu OH
polymer-bound phosphine palladium complex is rather compli-
cated; the non-crosslinked poly(chloromethylstyrene) is not
commercially available, and the chloromethylation requires the
use of carcinogenic chloromethyl methyl ether. To our know-
ledge, no Heck carbonylation catalyzed by a polymer-bound
sulfur palladium complex has been reported. We prepared a
silica-supported poly[3-(2-cyanoethylsulfanyl)propylsiloxane
palladium] complex (‘Si’᎐S᎐Pd) from 3-(1,1,1-triethoxysilyl)-
propane-1-thiol and fused silica via hydrolysis, followed by
treatment with palladium chloride in acetone under a nitrogen
atmosphere (Scheme 1).
n
Scheme 2 Reagents and conditions: i, ‘Si’᎐S᎐Pd (1.5 mol%), Bu N
3
The initial experiment was carried out with iodobenzene add-
ing 1.5 mol% ‘Si’᎐S᎐Pd as catalyst. The polymeric palladium()
complex was reduced by the carbon monoxide in the reaction
mixture. We used n-butyl alcohol as the alcohol and tri-n-
butylamine as the base, since they boil well above the reaction
temperature used. The butoxycarbonylation reaction at 100 ЊC
required 25 h to go to completion and n-butyl benzoate was
obtained in 88% yield. When 1.5 mol% Pd(OAc) was used, n-
butyl benzoate was obtained in 70% yield under comparable
conditions. This polymeric palladium catalyst not only has
higher catalytic activity in the butoxycarbonylation of iodo-
2
3
(EtO)3SiCH2CH2CH2SH
+
CH2 CHCN
i
benzene than Pd(OAc) , but also can be recovered by simple
2
filtration. The activity of the recovered catalyst was tested after
two recycles and it was found that the yield of n-butyl benzoate
decreased by only 2 and 3% after each recycle, respectively.
The reaction is suitable for a variety of functional groups on
the aryl halides; both strongly electron donating and withdraw-
ing substituents can be present. The butoxycarbonylation of
various aryl iodides has been achieved with good to high yields.
These results are summarized in Table 1. The substituent effects
in the aryl iodides appeared to be less significant than in the aryl
bromides. Aryl bromides did not react unless they were strongly
activated with electron withdrawing substituents and in the
(
EtO)3SiCH2CH2CH2SCH2CH2CN
ii
O
iii
SiO2
O
SiCH2CH2CH2SCH2CH2CN('Si'
O
S)
'Si'
S
Pd
Scheme 1 Reagents and conditions: i, CH CH ONa; ii, SiO , H O,
3
2
2
2
toluene; iii, PdCl , CH COCH
2
3
3
presence of a catalytic amount of PPh . A similar observation
3
3
X-Ray photoelectron spectroscopy (XPS) of the polymeric
was also made by Heck using Pd(OAc) as catalyst in butoxy-
2
palladium complex showed that the binding energy (337.5 eV)
carbonylation of aryl bromides. We found that adding 2 mol%
II
of Pd 3d
5
¯
in the polymeric palladium catalyst was lower than the
PPh caused activated aryl bromides to react and produce esters
2
3
II
bindingenergy(338.3eV)of Pd 3d
5
in PdCl . Thisresult suggests
in moderate yields. However, the butoxycarbonylation of aryl
¯
2
2
J. Chem. Soc., Perkin Trans. 1, 1997
2273

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3
bromides with electron donating substituents was very slow
butyl alcohol (2 cm ) were added by syringe and a slow stream
of CO was passed into the flask. The mixture was stirred at
100 ЊC for 25 h. The reaction mixture was cooled and dissolved
even in the presence of PPh and only trace amounts of prod-
3
ucts were obtained. Benzyl bromide also reacted with CO and
3
n-butyl alcohol without PPh , but the yield was low. In the
in diethyl ether (60 cm ). The ‘Si’᎐S᎐Pd was separated from the
3
3
presence of a catalytic amount of PPh , the butoxycarbonyl-
mixture by filtration, washed with distilled water (2 × 10 cm ),
3
3
3
ation of 1-bromonaphthalene gave an ester after 72 h in low
yield. Table 1 contains one example of particular interest: the
butoxycarbonylation of methyl p-iodobenzoate gave a 90%
yield of n-butyl methyl terephthalate with none of the sym-
metrical esters being formed.
ethanol (2 × 10 cm ) and diethyl ether (2 × 10 cm ) and reused
in the next run. The ethereal solution was washed with 20%
3
aqueous hydrochloric acid (2 × 10 cm ), saturated aqueous
sodium hydrogen carbonate (10 cm ) and distilled water (3 × 10
cm ). The ethereal layer was dried over anhydrous magnesium
3
3
In conclusion, the silica-supported poly[3-(2-cyanoethyl-
sulfanyl)propylsiloxane palladium] complex is an efficient cat-
alyst for butoxycarbonylation of aryl halides. This polymeric
palladium catalyst not only has higher catalytic activity than
sulfate and concentrated under reduced pressure. The residue
was purified by preparative TLC on silica gel (light petroleum–
3
ethyl acetate 19:1) to afford n-butyl benzoate (0.47 g, 88%);
Ϫ1
νmax(film)/cm 3060, 2919, 2880, 1718, 1600, 1450, 1380, 1110,
Pd(OAc) , but also can be reused without loss of activity. The
700; δ (90 MHz, CCl , Me Si) 0.98 (t, J 7.5, 3 H), 1.17–1.84 (m,
2
H
4
4
present method has the advantages of ease of handling, separ-
ation of the products and reuse of the catalyst.
4 H), 4.27 (t, J 6.0, 2 H), 7.13–7.60 (m, 3 H), 7.77–8.10 (m, 2 H).
9 Ϫ1
n-Butyl 4-methylbenzoate. νmax(film)/cm 3050, 2940, 2860,
710, 1600, 1450, 1380, 1170, 840; δ (90 MHz, CDCl , Me Si)
.97 (t, J 7.5, 3 H), 1.16–1.90 (m, 4 H), 2.39 (s, 3 H), 4.22 (t,
1
0
H
3
4
Experimental†
J 6.0, 2 H), 7.12 (d, J 9.0, 2 H), 7.81 (d, J 9.0, 2 H).
3
Ϫ1
Synthesis of 3{[3-(1,1,1-triethoxysilyl)propyl]sulfanyl}propane-
nitrile
To a mixture of 3-(1,1,1-triethoxysilyl)propane-1-thiol (11.90 g,
n-Butyl 4-methoxybenzoate.
2870, 1710, 1600, 1450, 1380, 1260, 1100, 845; δ
Me Si) 0.93 (t, J 7.5, 3 H), 1.06–1.83 (m, 4 H), 3.75 (s, 3 H), 4.16
ν
max(film)/cm
3050, 2920,
(
90 MHz, CCl4,
H
4
(
t, J 6.0, 2 H), 6.83 (d, J 9.0, 2 H), 7.89 (d, J 9.0, 2 H).
5
0 mmol) and sodium ethoxide (0.07 g, 1.03 mmol) at 0 ЊC was
10 Ϫ1
n-Butyl 4-chlorobenzoate. νmax(film)/cm 3070, 2930, 2860,
715, 1590, 1455, 1380, 1170, 845; δ (90 MHz, CCl , Me Si)
added dropwise acrylonitrile (3.97 g, 75 mmol). After being
stirred for 1 h, the mixture was warmed to room temperature
and stirred for 20 h. The reaction mixture was diluted with
1
0
H
4
4
.92 (t, J 7.5, 3 H), 1.10–1.83 (m, 4 H), 4.18 (t, J 6.0, 2 H), 7.30
3
diethyl ether (60 cm ) and filtered. The filtrate was washed with
(d, J 9.0, 2 H), 7.86 (d, J 9.0, 2 H).
n-Butyl 4-nitrobenzoate. νmax(KBr)/cm 3050, 2940, 2860,
1715, 1600, 1525, 1450, 1350, 1100, 870; δ (
90 MHz, CDCl3,
H
3
11
Ϫ1
5
(
% AcOH (10 cm ), 10% aqueous sodium hydrogen carbonate
3
3
10 cm ) and water (3 × 10 cm ) and dried over CaCl . After
2
Me4Si) 0.98 (t, J 7.5, 3 H), 1.19–1.87 (m, 4 H), 4.26 (t, J 6.0, 2
concentration under reduced pressure, the residue was distilled
in vacuo to give the title compound (10.20 g, 70%), bp 142–
H), 7.34 (d, J 9.0, 2 H), 7.92 (d, J 9.0, 2 H).
3
Ϫ1
n-Butyl methyl terephthalate. νmax(film)/cm 3060, 2930,
860, 1718, 1500, 1440, 1100, 870; δ (90 MHz, CDCl , Me Si)
1
44 ЊC/26.6 Pa (Found: C, 49.25; H, 8.36; N, 4.93; S, 10.69.
C H NO SSi requires C, 49.48; H, 8.59; N, 4.81; S, 10.99%);
2
H
3
4
1
2
25
3
Ϫ1
νmax(film)/cm 2930, 2860, 2260, 1080, 1190, 780; δ (90 MHz,
0.93 (t, J 7.5, 3 H), 1.15–1.85 (m, 4 H), 3.83 (s, 3 H), 4.20 (t,
J 6.0, 2 H), 7.84 (s, 4 H).
H
CDCl , Me Si) 0.62 (t, J 8.2, 2 H), 1.16 (t, J 7.0, 9 H), 1.43–1.85
3
4
ϩ
3
Ϫ1
m, 2 H), 2.43–2.76 (m, 6 H), 3.75 (q, J 7.0, 6 H); m/z 291 (M ,
n-Butyl 2-phenylacetate.
νmax(film)/cm 3060, 2940, 2870,
(
1725, 1600, 1450, 1060, 700; δ
(
90 MHz, CCl , Me Si) 0.93 (t,
2
8%) and 163 (100).
H
4 4
J 7.5, 3 H), 1.10–1.71 (m, 4 H), 3.51 (s, 2 H), 4.02 (t, J 6.0, 2 H),
Syntheses of ‘Si’᎐S and ‘Si’᎐S᎐Pd
Toluene (120 cm ) and fused silica (5.00 g) were placed in a flask
equipped with a magnetic stirrer and reflux condenser. After
stirring for 10 min, 3{[3-(1,1,1-triethoxysilyl)propyl]sulfanyl}-
propanenitrile (5.00 g) was added and the mixture was heated
7.05–7.42 (m, 5 H).
n-Butyl 1-naphthoate.
1710, 1590, 1450, 1060, 1010, 780; δ
3
3
Ϫ1
νmax(film)/cm
3050, 2930, 2870,
(
90 MHz, CCl , Me Si)
H
4
4
0
.95 (t, J 7.5, 3 H), 1.12–1.86 (m, 4 H), 4.23 (t, J 6.0, 2 H), 7.23–
7
.52 (m, 3 H), 7.56–8.15 (m, 3 H), 8.61–8.95 (m, 1 H).
3
to reflux for 48 h under nitrogen. Distilled water (30 cm ) was
added and after refluxing for another 48 h, the product was
allowed to cool, then filtered and dried at 200 ЊC in vacuo for 5
h. The resulting white powder was washed with acetone (3 × 20
cm ), followed by drying to give 6.80 g of ‘Si’᎐S. The sulfur
content was determined to be 6.02 wt% by elemental analysis.
References
1
D. Valentine, J. W. Tilley and R. A. LeMahieu, J. Org. Chem., 1981,
46, 4614.
N. A. Bumagin, K. V. Nikitin and I. P. Beletskaya, J. Organomet.
Chem., 1988, 358, 563.
3 A. Schoenberg, I. Bartoletti and R. F. Heck, J. Org. Chem., 1974, 39,
3318.
3
2
A mixture of ‘Si’᎐S (2.00 g) and PdCl (0.22 g, 1.20 mmol) in
2
3
acetone (50 cm ) was heated to reflux under nitrogen for 72 h.
The product was allowed to cool, then filtered. The resulting
4 T. Sakakura, M. Claisupakitsin, T. Hayashi and M. Tanaka, J.
Organomet. Chem., 1987, 334, 205.
5 A. Schoenberg and R. F. Heck, J. Org. Chem., 1974, 39, 2819.
3
yellow powder was washed with distilled water (3 × 10 cm ) and
3
acetone (3 × 10 cm ) and then dried in vacuo to afford 2.04 g of
6
T. Okano, N. Harada and J. Kiji, Bull. Chem. Soc. Jpn., 1994, 67,
329.
N. P. Reddy, M. L. Kantam and B. M. Choudary, Indian J. Chem.,
989, 28B, 105.
8 N. L. Holy, Chemtech., 1980, 366.
‘Si’᎐S᎐Pd. The sulfur and palladium content were 4.89 wt% and
2
4
.45 wt%, respectively.
7
1
Typical procedure for the butoxycarbonylation of aryl halides
with CO
9
H. M. Huang, S. X. Zhu, W. S. Qi and C. W. Na, Jilin Daxue Ziran
Kexue Xuebao, 1987, 71 (Chem. Abstr., 1988, 109, 92 412f).
3
Into a 50 cm flask, fitted with a magnetic stirrer, gas inlet tube
1
1
0 R. M. Jacobson, Synth. Commun., 1978, 8, 33.
1 M. Sekiya, Y. Ohashi, Y. Terao and K. Ito, Chem. Pharm. Bull.,
and reflux condenser, were placed ‘Si’᎐S᎐Pd (0.01 g, 0.04
mmol). The atmosphere was replaced with carbon monoxide.
1
976, 24, 369.
n
Iodobenzene (0.61 g, 3 mmol), Bu N (0.65 g, 3.5 mmol) and n-
3
Paper 7/02085F
Received 25th March 1997
Accepted 10th June 1997
†
J Values are given in Hz.
2
274
J. Chem. Soc., Perkin Trans. 1, 1997