Recyclable tridentate stable palladium(II) PCP-type catalysts supported on silica for the selective synthesis of lactones

Article abstract of DOI:10.1002/adsc.200404109

Five- or seven-membered ring lactones are synthesized, in good selectivity and high yields, by the cyclocarbonylation reaction of 2-allylphenols, using a tridentate diphosphinoaryl ligand (PCP-type) palladium(II) catalyst immobilized on silica (A) and silica supported dendrimers (B, C and D). These immobilized catalysts, which are highly active and can be recycled by simple filtration in air, and reused with only moderate loss of activity, combine the advantages of heterogeneous and homogeneous catalysts. These complexes are also stable towards oxygen and moisture.

Full text of DOI:10.1002/adsc.200404109

FULL PAPERS
Recyclable Tridentate Stable Palladium(II) PCP-Type Catalysts
Supported on Silica for the Selective Synthesis of Lactones
Ratana Chanthateyanonth, Howard Alper*
Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa,
Ontario, Canada K1N 6N5
Fax: (þ1)-613-562-5871, e-mail: halper@uottawa.ca
Received: April 14, 2004; Accepted: July 13, 2004
Abstract: Five- or seven-membered ring lactones are with only moderate loss of activity, combine the ad-
synthesized, in good selectivity and high yields, by vantages of heterogeneous and homogeneous cata-
the cyclocarbonylation reaction of 2-allylphenols, us- lysts. These complexes are also stable towards oxygen
ing a tridentate diphosphinoaryl ligand (PCP-type) and moisture.
palladium(II) catalyst immobilized on silica (A) and
silica supported dendrimers (B, C and D). These im-
mobilized catalysts, which are highly active and can Keywords: carbonylation; dendrimers; heterogeneous
be recycled by simple filtration in air, and reused catalysts; immobilization; lactones; palladium
Introduction
Carbonylation involves the direct insertion of carbon the generation zero dendrimer (G-0), (A), obtained by
monoxide into an organic substrate. This reaction usual- the immobilization of a PCP-type palladium(II) com-
ly occurs in the presence of a transition metal complex as plex onto silica, was described in the literature (Fig-
the catalyst. Palladium catalysts are especially useful for ure 1).[23]
carbonylation reactions leading to amides,[1–4] acids,[5,6]
In this paper, we report the cyclocarbonylation reac-
ketones,[7] esters,[8–10] lactones,[11–14] and other com- tion of 2-allylphenols to form five- or seven-membered
pounds.[15,16] One of the most interesting applications ring lactones in good selectivity and in high yields by
of the carbonylation reactionis for intramolecular cyclo- generation zero dendrimer (G-0) (A). Subsequently,
carbonylation to give heterocyclic compounds such as generation one dendrimer (G-1) (B) and generation
five-, six- and seven-membered lactones in moderate two dendrimer (G-2) (C) polyaminoamido (PAMAM)
to high yields.[11,12,14] Some of these products are pharma- dendrimers were synthesized (Figures 2 and 3). A simi-
cologically active, or are used as intermediates to syn- lar dendrimer, but with a 6-carbon spacer group, was
thesize biologically active compounds[17] or polyest- also synthesized as another generation one complex
ers,[18,19] and are often less readily accessible by conven- (G-1) (D) to compare the reactivity with that of (G-1)
tional synthetic methods.
(B) (Figure 4). These complexes were found to be effec-
It has been shown that a dendrimer–palladium com- tive catalysts for the cyclocarbonylation reaction. In ad-
plex immobilized on silica is catalytically active for sev- dition, the catalysts can be recycled by simple filtration
eral reactions,[20–22] including carbonylation reactions.[10] in air and reused with only moderate loss of activity.
Immobilization of the homogeneous catalyst by means
of a heterogeneous support can, in principle, retain the
properties observed for the homogeneous system and
allow simple separation from the reaction mixture. It is
known that palladium complexes with pincer ligands
(e.g., PCP, this ligand comprises an anionic aryl ring
which is ortho, ortho-disubstituted with CH2PR2. The
latter groups coordinate to the palladium centre result-
À
ing in two metallacycles which share the Pd C bond)
display extraordinary thermal stability (up to 1808C)
Figure 1. Generation zero silica-supported dendrimer (G-0)
and are not sensitive to oxygen or moisture. Recently, (A).
Adv. Synth. Catal. 2004, 346, 1375–1384
DOI: 10.1002/adsc.200404109
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FULL PAPERS
The Catalytic Properties of A (G-0), B(G-1), C (G-2)
and D (G-1) for the Intramolecular
Cyclocarbonylation Reaction
The catalytic reactivity of A (G-0) was investigated for
the intramolecular cyclocarbonylation of 2-allylphenol.
First, 2-allylphenol was treated with a 1/1 mixture of CO/
H2 (total pressure 600 psi) and dppb in toluene at 1208C
for 48 h to form the corresponding lactone in 93% yield
and in 78% selectivity for the seven-membered ring lac-
tone (7) (entry 1, Table 1). Small amounts of the six- and
five-membered ring lactones (8 and 9) were also formed.
Variousconditions were usedto obtain a better yield and
increased selectivity, including changing the relative
pressures of carbon monoxide and hydrogen, tempera-
ture, and solvent [Eq. (1)]. The results are summarized
in Table 1.
Figure 2. Generation one silica supported dendrimer (G-1)
(B).
Figure 3. Generation two silica supported dendrimer (G-2)
(C).
ð1Þ
The reaction yields increased by increasing the tempera-
ture to 1408C or by using CH2Cl2 instead of toluene, but
there was only moderate selectivity for the five-mem-
bered ring lactone (entries 2 and 3, Table 1). The five-
membered ring lactone was formed in good yield and
in high selectivity using a 1/5 mixture of CO/H2 (total
pressure 600 psi) in CH2Cl2, at 1408C (entry 5, Table 1).
The selectivity for the seven-membered ring lactone in-
creased in the absence of hydrogen. The best yield and
selectivityfor the7-membered ringlactone was obtained
when the pressure of CO was 400 psi in toluene at 1408C
(entry 9, Table 1). The seven-membered ring lactone
was also obtained in good yield, and in high selectivity,
with a 5/1 mixture of CO/H2 (total pressure 600 psi) in
toluene at 1208C (entry 13, Table 1). Traces of lactones
were obtained at lower temperature (1008C) or at lower
pressure (200 psi) (entries 6 and 8, Table 1). Substitution
of bidentate (dppb) by monodentate (PPh3) ligands af-
forded moderate selectivity for the seven-membered
Figure 4. Generation one silica supported dendrimer (G-1)
(D).
Results and Discussion
Synthesis and Characterization of Generation One
Dendrimer (G-1) (B), Generation Two Dendrimer
(G-2) (C) and Generation One Dendrimer (G-1) (D)
Silica Supported PCP-Type Palladium(II) Complexes
Compounds 1, 2 and 5 were prepared according to liter- ring lactone in 54% yield (entry 14, Table 1).
ature methods.[23,24] Generation one dendrimer (G-1)
The recyclability of the catalyst was studied, using sev-
(B), generation two dendrimer (G-2) (C) and genera- eral of the best conditions (entries 5, 9 and 13 in Ta-
tion one dendrimer (G-1) (D) were prepared by a strat- ble 1). It was found that under the conditions of entry 5,
egy similar to that described the for generation zero den- Table 1, the catalyst A (G-0) decomposed in the third
drimer (G-0) (A),[23] (Schemes 1 and 2). The CP/MAS run (Table 2).
31P NMR and 13C NMR spectra of compounds B, C,
Using the conditions of entry 9, Table 1, the catalyst A
and D were similar to those of A reported previously. (G-0) also decomposed in the third run (Table 3).
The percentages of palladium, determined by ICP anal-
yses, were 3.22%, 4.29 and 2.84%, respectively.
Nevertheless, these conditions are still of interest
since the homogeneous hydridoaquopalladium complex
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FULL PAPERS
Scheme 1. Preparation of generation one (G-1) (B), n¼1 and (D), n¼3.
trans-[(Cy3P)2Pd(H)(H2O)]BF4, in the absence of hy-
When catalyst A (G-0) was replaced by B (G-1),
drogen, gave only traces of lactones.[11] In addition, het- C (G-2), or D (G-1) under the same conditions, similar
erogeneous Pd-clay, in the absence of hydrogen, afford- yields and selectivities were obtained. The reactivities
ed only 37% lactones with high selectivity for the seven- of B (G-1), C (G-2), and D (G-1) correspond to those
membered ring product.[12] Therefore, the catalytic reac- mentioned previously (Tables 7 and 8).
tivities of B (G-1), C (G-2), and D (G-1) were also inves-
We also investigated the effect of changing the sub-
tigated under these conditions. We found similar results strate for the cyclocarbonylation reaction by replacing
to those obtained for catalyst A (G-O): the reactions 2-allylphenol with 2-allyl-6-methylphenol and using A
worked well for the first and second runs but the catalyst (G-0) as the catalyst. The yield was similar to 2-allylphe-
decomposed after that (Tables 4 and 5). The catalyst nol, and the catalyst could be recycled three times
containing a 6-carbon spacer group, (G-1) (D), was [Eq. (2), Table 9]. It was also noticed that the selectivi-
more reactive than B (G-1), and C (G-2) was more reac- ties were slightly better and the five-membered ring lac-
tive than either B (G-1) or D (G-1).
tone was formed only in traces, if at all. This might be due
It was found that catalyst A (G-O) could be recycled to the steric and/or electronic effects of the methyl
five times, under the conditions of entry 13, Table 1 (5/1 group, which is ortho to the hydroxy group.
mixture of CO/H2, total pressure 600 psi, in toluene at
1208C) (Table 6).
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Ratana Chanthateyanonth, Howard Alper
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Scheme 2. Preparation of generation two (G-2) (C).
We continued the investigation of the effect of different
substrates by replacing 2-allyl-6-methylphenol with 2-
allyl-4-chlorophenol. Under the same conditions, the se-
lectivity was similar to 2-allylphenol but different from
that of 2-allyl-6-methylphenol [Eq. (3), Table 10]. Clear-
ly, these results show that the cyclocarbonylation is not
sensitive to electronic effects but principally steric hin-
drance affects the selectivity of this reaction.
ð2Þ
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FULL PAPERS
Table 1. Catalytic cyclocarbonylation of 2-allylphenol by A (G-0).[a]
Entry
Temperature
[ 8C]
PCO
[psi]
PH2
[psi]
,
Solvent
Total
Product
TON
[mol of product/
mol of Pd]
Yield [%][b]
Distribution,[c]
%
7
8
9
1
2
3
4
5
6
7
8
9
10
11
12
13
14
120
140
120
120
140
120
120
100
140
130
120
140
120
120
300
300
300
100
100
200
400
400
400
400
600
600
500
500
300
300
300
500
500
0
0
0
0
0
Toluene
Toluene
CH2Cl2
Toluene
CH2Cl2
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
93
>99
>99
>99
>99
11
63
3
98
92
78
24
28
77
5
91
86
86
86
83
82
78
83
63
11
24
25
8
13
5
11
52
47
15
82
4
1
7
5
3
118
127
127
127
127
14
13
7
83
4
11
14
15
16
10
28
125
117
115
123
127
69
0
0
100
100
90
96
3
6
7
9
>99
54[d]
[a]
Reactions were conducted using 50 mg (0.8ꢀ10À2 mmol) of A and 1 mmol of 2-allylphenol for 48 h.
[b, c] Determined by NMR and GC.
[d]
Using PPh3 instead of dppb.
Table 2. Catalytic cyclocarbonylation of 2-allylphenol by A
(G-0);[a] a recycling study using 1: 5 CO/H2.
Run No
Yield [%][b]
Product Distribution,[c]
%
7
8
9
2
3
97
38
7
54
21
36
72
10
ð3Þ
[a]
Reactions were conducted using 50 mg of A (0.8ꢀ10À2
mmol), 0.04 mmol of dppb and 1 mmol of 2-allylphenol
for 48 h in CH2Cl2 at 600 psi and 1408C.
The homogeneous complex, 16 (Figure 5), was also ex-
amined as a catalyst for the cyclocarbonylation reaction
of 2-allylphenol so as to compare the results with those
obtained using catalyst A (G-0) (Table 11).
[b, c] Determined by NMR and GC.
It was found that in the absence of dppb, lactones were
formed in low yield (entry 1, Table 11). Similar results
were obtained for the heterogeneous catalyst A (G-0).
Lactones were synthesized in high yields when dppb
was added but only with moderate selectivity for the sev-
en-membered ring lactone (entry 2, Table 11). This is
significantly different from the case of A (G-0), B (G-1),
C (G-2), or D (G-1). Aminopropyl silica gel (Figure 6)
or N-[3,5-bis(diphenylphosphinoylmethyl)phenyl]suc-
cinamic acid (17) (Figure 7) were added to the reaction
but no significant change in the selectivity was noticed.
Table 3. Catalytic cyclocarbonylation of 2-allylphenol by A
(G-0);[a] a recycling study using only CO.
Run No
Yield [%][b]
Product Distribution,[c]
%
7
8
9
2
3
96
11
88
86
9
14
3
0
[a]
Reactions were conducted using 50 mg of A (0.8ꢀ10À2
mmol), 0.04 mmol of dppb and 1 mmol of 2-allylphenol
for 48 h in toluene at 400 psi and 1408C.
[b, c] Determined by NMR and GC.
Figure 5. Complex 16.
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Ratana Chanthateyanonth, Howard Alper
Table 4. Catalytic cyclocarbonylation of 2-allylphenol by B (G-1), C (G-2) or D (G-1);[a] using only CO.
FULL PAPERS
Catalyst
Yield [%][b]
Product Distribution,[c]
%
TON [mol of product/mol of Pd]
7
8
9
B
C
D
97
91
98
89
84
82
9
11
8
2
5
10
128
180
147
[a]
Reactions were conducted using 25 mg of catalyst B (0.8ꢀ10À2 mmol) or D (0.7ꢀ10À2 mmol), or 25 mg of catalyst C
(1.0ꢀ10À2 mmol), 0.04 mmol of dppb, and 1 mmol of 2-allylphenol for B or D, or 2 mmol of 2-allylphenol for C for
48 h in toluene at 400 psi and 1408C.
[b, c] Determined by NMR.
Table 5. Catalytic cyclocarbonylation of 2-allylphenol by B
(G-1), C (G-2) or D (G-1);[a] a recycling study using only
CO.
Catalyst Run No Yield [%][b] Product Distribution,[c]
%
Figure 6. Aminopropyl silica gel.
7
8
9
B
C
D
2
3
2
3
2
3
96
75
91
69
88
46
87
90
84
86
89
86
9
8
11
11
6
4
2
5
3
5
3
11
[a]
Reactions were conducted using 25 mg of catalyst B
(0.8ꢀ10À2 mmol) or D (0.7ꢀ10À2 mmol), or 25 mg of
catalyst C (1.0ꢀ10À2 mmol), 0.04 mmol of dppb, and
1 mmol of 2-allylphenol for B or D, or 2 mmol of 2-allyl-
phenol for C for 48 h in toluene at 400 psi and 1408C.
Figure 7. N-[3,5-Bis(diphenylphosphinoylmethyl)phenyl]suc-
cinamic acid (17).
[b, c] Determined by NMR.
and D (G-1) gave appreciably different yields and selec-
tivities under the same conditions when compared with
the work by El Ali and coworkers using the hydrido-
aquopalladium complex trans-[(Cy3P)2Pd(H)(H2O)]BF4
or Pd(OAc)2 as homogeneous catalysts.[11] Therefore,
the mechanism for the cyclocarbonylation reaction
might be different from that which was previously pro-
posed. Typically, temperatures of 1208C, and addition
of diphosphine ligands (dppb), are required, which sug-
gest the possibility of diphosphine ligand exchange be-
tween dppb and PCP complexes to palladium. The ob-
served different selectivities between A (G-0), B (G-1),
C (G-2), or D (G-1) and compound 16 might be due to
the substantial difference in size between heterogene-
ous catalysts A (G-0), B (G-1), C (G-2) or D (G-1)
and compound 16. The effect of substituents on the phe-
nyl ring could also be investigated to determine the in-
fluence of electron-donating/withdrawing substituents
Table 6. Catalytic cyclocarbonylation of 2-allylphenol by A
(G-0);[a] a recycling study using 5: 1 CO/H2.
Run No
Yield [%][b]
Product Distribution,[c]
%
7
8
9
2
3
4
5
93
>99
91
80
87
81
80
13
9
14
11
7
4
5
9
98
[a]
Reactions were conducted using 50 mg of A (0.8ꢀ10À2
mmol), 0.04 mmol of dppb and 1 mmol of 2-allylphenol
for 48 h in toluene at 600 psi and 1208C.
[b, c] Determined by NMR and GC.
Running the reaction in the absence of hydrogen for on the ring as well as the steric effect.
16 gave lactones in high yield, comparable to the case
when catalysts A (G-0), B (G-1), C (G-2), or D (G-1)
were used but the selectivity for the seven-membered Conclusions
ring lactone was moderate.
The cyclocarbonylation reactions of 2-allylphenol in We have shown that the catalysts obtained by immobili-
the presence of complexes 16, A (G-0), B (G-1), C (G-2) zation of a PCP-type palladium(II) complex onto silica
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Tridentate Stable Palladium(II) PCP-Type Catalysts
Table 7. Catalytic cyclocarbonylation of 2-allylphenol by B (G-1), C (G-2) or D (G-1);[a] using 5: 1 CO/H2.
FULL PAPERS
Catalyst
Yield [%][b]
Product Distribution,[c]
%
TON [mol of product/mol of Pd]
7
8
9
B
C
D
97
98
98
85
89
80
10
10
12
5
1
8
128
194
147
[a]
Reactions were conducted using 25 mg of catalyst B (0.8ꢀ10À2 mmol) or D (0.7ꢀ10À2 mmol), or 25 mg of catalyst C
(1.0ꢀ10À2 mmol), 0.04 mmol of dppb, and 1 mmol of 2-allylphenol for B or D, or 2 mmol of 2-allylphenol for C for
48 h in toluene at 600 psi and 1208C.
[b, c] Determined by NMR.
Table 8. Catalytic cyclocarbonylation of 2-allylphenol by B
(G-1), C (G-2) or D (G-1);[a] a recycling study using 5: 1
CO/H2.
and silica supported dendrimers are effective catalysts
for the cyclocarbonylation reaction of 2-allylphenol
yielding five- or seven-membered ring lactones in
good selectivity and in high yields. These complexes,
which are stable towards oxygen and moisture, can be
recycled effectively. The dendritic systems show higher
activity compared to the non-dendritic systems.
Catalyst Run No Yield [%][b] Product Distribution,[c]
%
7
8
9
B
C
D
2
3
2
3
2
3
85
97
97
92
87
89
85
82
88
86
86
10
11
11
10
11
8
1
4
7
2
3
6
Experimental Section
>99
General
[a]
Reactions were conducted using 25 mg of catalyst B
(0.8ꢀ10À2 mmol) or D (0.7ꢀ10À2 mmol), or 25 mg of
catalyst C (1.0ꢀ10À2 mmol), 0.04 mmol of dppb, and
1 mmol of 2-allylphenol for B or D, or 2 mmol of 2-allyl-
phenol for C for 48 h in toluene at 600 psi and 1208C.
Chemicals were purchased from Aldrich, Strem and Lancaster
Chemical companies were used without further purification.
Generation zero dendrimer (G-0) (A), PAMAM-SiO2 den-
drimer compounds 1, 5 and N-[3,5-bis(diphenylphosphanyl-
methyl)phenyl]succinamic acid (2) were prepared by literature
[b, c] Determined by NMR.
Table 9. Catalytic cyclocarbonylation of 2-allyl-6-methylphenol by A (G-0);[a] using 5: 1 CO/H2.
Run No
Yield [%][b]
Product Distribution,[c]
%
TON [mol of product/mol of Pd]
10
11
12
1
2
3
>99
96
>99
88
91
88
11
9
11
1
0
1
127
[d]
–
[d]
–
[a]
Reactions were conducted using 50 mg (0.8ꢀ10À2 mmol) of A, 0.04 mmol of dppb and 1 mmol of 2-allyl-6-methylphenol
for 48 hours in toluene at 600 psi and 1208C.
[b, c] Determined by NMR and GC.
[d]
Palladium loading was not measured.
Table 10. Catalytic cyclocarbonylation of 2-allyl-4-chlorophenol by A (G-0);[a] using 5: 1 CO/H2.
Run No
Yield [%][b]
Product Distribution,[c]
%
TON [mol of product/mol of Pd]
13
14
15
1
2
3
98
90
97
81
88
84
9
9
11
10
3
5
125
[d]
–
[d]
–
Reactions were conducted using 50 mg (0.8ꢀ10À2 mmol) of A, 0.04 mmol of dppb and 1 mmol of 2-allyl-4-chlorophenol
for 48 hours in toluene at 600 psi and 1208C.
[a]
[b, c] Determined by NMR and GC.
[d]
Palladium loading was not measured.
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Table 11. Catalytic cyclocarbonylation of 2-allylphenol by 16;[a] using 5: 1 CO/H2.
Entry
dppb [mmol]
17 [mmol]
Silica [mg]
Yield [%][b]
Product Distribution,[c]
%
7
8
9
1
2
3
4
–
–
–
0.03
–
–
–
–
50
25
99
95
99
48
48
59
54
26
20
21
18
26
32
20
28
0.04
0.04
0.04
[a]
Reactions were conducted using 7 mg (1.5ꢀ10À2 mmol) of catalyst 16 and 1 mmol of 2-allylphenol for 48 h in toluene at
600 psi and 1208C.
[b, c] Determined by NMR and GC.
procedures.[23,24] All the reaction products are known com-
pounds and have spectral data in accord with that in the litera-
ture.[25–28]
All reactions were carried out under an atmosphere of nitro-
gen. All manipulations of air-sensitive materials were carried
out using standard Schlenk techniques. Solvents were purified
and dried following standard procedures.[29]
ture was stirred at room temperature for 1 day and then heated
at 458C for 5 days. The suspension was filtered, washed with di-
chloromethane several times, and dried under vacuum to af-
ford 4, n¼1 as a pale yellow solid; yield: 0.7 g (49%); 31P CP/
MAS NMR: d¼ À8.6 and 27.9 (phosphine oxide); 13C CP/
MAS NMR: d¼171.4, 157.3, 142.4, 107.7, 40.8, 20.3, 9.6; ICP
analysis: mass % P 2.37.
Solution NMR spectra were recorded at 20.58C, unless oth-
erwise indicated, on a Varian Gemini-200 (1H at 199.97 MHz
and 13C{1H} at 50.28 MHz) or a Bruker 300 NMR spectrometer
(1H at 300.13 MHz, 13C{1H} at 75.48 MHz and 31P{1H} at
Synthesis of the Generation One Dendrimer, (G-1) (B)
1
121.49 MHz). H and 13C NMR spectra are reported in ppm,
A suspension of compound 4 (n¼1; 0.6 g, 0.24 mmol), and
Pd(TFA)2 (0.08 g, 0.24 mmol) in THF (50 mL) was stirred at
room temperature for 4 days. The suspension was filtered,
washed with THF several times, and dried under vacuum to af-
ford generation one dendrimer (G-1) (B) as a dark yellow sol-
id; yield: 0.6 g (84%); 31P CP/MAS NMR: d¼38.7 and 29.3
(phosphine oxide); 13C CP/MAS NMR: d¼172.1, 157.5,
141.8, 130.1, 108.4, 50.4, 40.5, 31.0, 20.4, 10.0; ICP analysis:
mass % Pd 3.22.
with the residual non-deuterated solvent in the deuterated sol-
vents served as a reference. 31P chemical shifts are reported in
ppm relative to the external standard, 85% H3PO4. The 13C and
31P CP/MAS (cross polarization/magic angle spinning) NMR
spectra, frequency 50.32 MHz and 81.00 MHz respectively,
were recorded on a Bruker ASX-200 spectrometer. Solid sam-
ples were prepared by transfer of the relevant material to a
5 mm o.d. pyrex NMR tube and connected to a high vacuum
stopcock in an M. Braun GmbH glovebox. The sample was
then removed from the drybox, placed under high vacuum
and, without breaking vacuum, sealed off at 30 mm lengths.
The tubes were then placed in zirconia rotors used in the Bruk-
er ASX-200 instrument.
Synthesis of Compound 6
To a solution of 2 (2.9 g, 4.9 mmol) and 4-(dimethylamino)pyr-
idine (DMAP; 0.6 g, 4.9 mmol) in dichloromethane (70 mL)
was added 1,3-dicyclohexylcarbodiimide (DCC; 1.01 g,
4.9 mmol) in dichloromethane (5 mL) and N-hydroxysuccini-
mide (0.6 g, 4.9 mmol) at 08C. The mixture was stirred at
room temperature for 18 h. The white solid was filtered and
the solvent was evaporated under reduced pressure, affording
compound 3 as a yellow solid. DMAP (0.6 g, 4.9 mmol) in di-
chloromethane (50 mL) and PAMAM-SiO2 dendrimer com-
pound 5 (0.5 g, 0.28 mmol) were added, the reaction mixture
was stirred at room temperature for 1 day and then heated at
458C for 7 days. The suspension was filtered, washed with di-
chloromethane several times, and dried under vacuum to af-
ford 6 as a pale yellow solid; yield: 0.8 g (52%). 31P CP/MAS
NMR: d¼ À11.3 and 27.1 (phosphine oxide); 13C CP/MAS
NMR: d¼172.7, 157.7, 143.3, 108.5, 40.2, 26.0, 10.6; ICP analy-
sis: mass % P 3.0.
High-pressure reactions were conducted in stainless steel
autoclaves fitted with a screw cap from Parr Instruments. The
reactions with carbon monoxide were carried out in a fume
hood with CO detectors installed nearby.
ICP analyses were carried out by Galbraith Laboratories,
Knoxville, TN. or by the Institute for National Measurement
Standards Chemical Metrology at the National Research
Council, Ottawa. Gas chromatography was carried out using
a Hewlett Packard HP 5890 Series II chromatograph.
Synthesis of Compound 4 (n¼1)
To a solution of 2 (1.7 g, 2.9 mmol) and 4-(dimethylamino)pyr-
idine (DMAP; 0.35 g, 2.9 mmol) in dichloromethane (30 mL)
was added 1, 3-dicyclohexylcarbodiimide (DCC; 0.59 g,
2.9 mmol) in dichloromethane (2 mL) and N-hydroxysuccini-
mide (0.33 g, 2.9 mmol) at 08C. The mixture was stirred at
room temperature for 18 h. The white solid was filtered and
the solvent was evaporated under reduced pressure, affording
compound 3 as a yellow solid. DMAP (0.35 g, 2.9 mmol) in di-
chloromethane (80 mL) and PAMAM-SiO2 dendrimer com-
pound 1 (n¼1; 0.5 g, 0.37 mmol) were added, the reaction mix-
Synthesis of a Generation Two Dendrimer, (G-2) (C)
A suspension of compound 6 (0.7 g, 0.17 mmol), and Pd(TFA)2
(0.11 g, 0.34 mmol) in THF (50 mL) was stirred at room tem-
perature for 5 days. The suspension was filtered, washed with
1382
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Tridentate Stable Palladium(II) PCP-Type Catalysts
FULL PAPERS
THF several times, and dried under vacuum to afford genera-
tion two dendrimer (G-2) (C) as a dark yellow solid; yield: 0.7 g
(88%). 31P CP/MAS NMR: d¼36.3 and 28.7 (phosphine ox-
ide); 13C CP/MAS NMR: d¼172.5, 156.3, 142.3, 131.4, 108.4,
48.1, 40.9, 31.0, 26.0, 10.3: ICP analysis mass: % Pd 4.29.
Acknowledgements
We are grateful to NSERC for support of this research, Dr.
Glenn Facey for recording the CP/MAS NMR spectra, and to
Dr. Victor Boyko of the National Research Council, Canada,
for ICP measurements.
Synthesis of Compound 4 (n¼3)
To a solution of 2 (1.7 g, 2.9 mmol) and 4-(dimethylamino)pyr-
idine (DMAP; 0.35 g, 2.9 mmol) in dichloromethane (30 mL)
was added 1, 3-dicyclohexylcarbodiimide (DCC; 0.59 g,
2.9 mmol) in dichloromethane (2 mL) and N-hydroxysuccini-
mide (0.33 g, 2.9 mmol) at 08C. The mixture was stirred at
room temperature for 18 h. The white solid was filtered and
the solvent was evaporated under reduced pressure, affording
compound 3 as a yellow solid. DMAP (0.35 g, 2.9 mmol) in di-
chloromethane (80 mL) and PAMAM-SiO2 dendrimers, com-
pound 1 (n¼3; 0.5 g, 0.34 mmol) were added, the reaction mix-
ture was stirred at room temperature for 1 day and then heated
at 458C for 5 days. The suspension was filtered, washed with di-
chloromethane several times, and dried under vacuum to af-
ford 4, n¼3 as a pale yellow solid; yield: 0.7 g (51%); 31P CP/
MAS NMR: d¼ À11.2; 13C CP/MAS NMR: d¼172.9, 158.9,
129.1, 107.8, 39.9, 27.9, 10.6; ICP analysis: mass % P 2.33.
References
[1] K. Ueda, Y. Sato, M. Mori, J. Am. Chem. Soc. 2000, 122,
10722–10723.
[2] R. K. Boeckman, J. E. Reed, P. Ge, Org. Lett. 2001, 3,
3651–3653.
[3] N.-F. K. Kaiser, A. Hallberg, M. Larhed, J. Comb. Chem.
2002, 4, 109–111.
[4] O. Rahman, T. Kihiberg, B. Langstrom, J. Org. Chem.
2003, 68, 3558–3562.
[5] A. Seayad, S. Jayasree, R. V. Chaudhari, Org. Lett. 1999,
1, 459–461.
[6] V. K. Aggarwal, P. W. Davies, W. O. Moss, Chem. Com-
mun. 2002, 972–973.
[7] S. V. Gagnier, R. C. Larock, J. Am. Chem. Soc. 2003, 125,
4804–4807.
[8] C. Coperet, E.-I. Negishi, Org. Lett. 1999, 1, 165–167.
[9] Y. Liao, M. Reitman, Y. Zhang, R. Fathi, Z. Yang, Org.
Lett. 2002, 4, 2607–2609.
[10] S. Antebi, P. Arya, L. E. Manzer, H. Alper, J. Org. Chem.
2002, 67, 6623–6631.
Synthesis of the Generation One Dendrimer, (G-1)
(D)
A suspension of compound 4 (n¼3; 0.6 g, 0.22 mmol), and
Pd(TFA)2 (0.07 g, 0.22 mmol) in THF (50 mL) was stirred at
room temperature for 4 days. The suspension was filtered,
washed with THF several times, and dried under vacuum to af-
ford generation one dendrimer (G-1) (D) as a dark yellow sol-
id; yield: 0.6 g (75%); 31P CP/MAS NMR; d¼35.6; 13C CP/
MAS NMR: d¼172.8, 157.5, 143.3, 131.3, 106.8, 51.9, 40.5,
28.6, 22.7, 10.6; ICP analysis: mass % Pd 2.84.
[11] B. El Ali, K. Okuro, G. Vasapollo, H. Alper, J. Am.
Chem. Soc. 1996, 118, 4264–4270.
[12] A. Orejon, H. Alper, J. Mol. Catal. A 1999, 143, 137–142.
[13] J. Kiji, Y. Kondou, M. Asahara, Y. Yokoyama, T. Sagisa-
ka, J. Mol. Catal. A 2003, 197, 127–132.
[14] G. Vasapollo, G. Mele, B. El Ali, J. Mol. Catal. A 2003,
204–205, 97–105.
[15] E. W. Stern, M. L. Spector, J. Org. Chem. 1966, 31, 596–
597.
[16] M. Iwasaki, Y. Kobayashi, J.-P. Li, H. Matsuzaka, J. Org.
Chem. 1991, 56, 1922–1927.
[17] L. F. Bjeldanes, I.-S. Kim, J. Org. Chem. 1977, 42, 2333–
2335.
General Procedure for the Cyclocarbonylation
Reactions
A mixture of the 2-allylphenol (1 mmol), catalyst A (50 mg)
and 1,4-bis(diphenylphosphino)butane (dppb; 0.04 mmol) in
dry solvent (5 mL) was placed in a 45 mL autoclave equipped
with a magnetic stirring bar. The autoclave was flushed three
times with CO and then was pressured using a predetermined
ratio of carbon monoxide and hydrogen gases (see Tables). The
autoclave was placed in an oil bath preheated to the appropri-
ate temperature. The reaction mixture was magnetically stirred
for 48 h, cooled to room temperature, and the unreacted car-
bon monoxide was slowly released. The mixture was filtered
to separate the catalyst from the liquid phase. The catalyst
was washed several times with CH2Cl2 and dried under reduced
pressure before being recycled. The organic layer was concen-
trated by rotary evaporation affording an oil.
[18] M. Trollsa, J. L. Hedrick, D. Mecerreyes, Ph. Dubois, R.
Jerome, H. Ihre, A. Hult, Macromolecules 1998, 31,
2756–2763.
[19] T. F. Al-Azemi, L. Kondaveti, K. S. Bisht, Macromole-
cules 2002, 35, 3380–3386.
[20] M. K. Richmond, S. L. Scott, H. Alper, J. Am. Chem.
Soc. 2001, 123, 10521–10525.
[21] M. K. Richmond, S. L. Scott, G. P. A. Yap, H. Alper, Or-
ganometallics, 2002, 21, 3395–3400.
[22] H. Alper, P. Arya, S. C. Bourque, G. R. Jefferson, L. E.
Manzer, Can. J. Chem. 2000, 78, 920–924.
[23] R. Chanthateyanonth, H. Alper, J. Mol. Catal. A 2003,
201, 23–31.
[24] S. C. Bourque, F. Maltais, W-J. Xiao, O. Tardif, H. Alper,
P. Arya, L. E. Manzer, J. Am. Chem. Soc. 1999, 121,
3035–3038.
Analogous procedures were used for catalysts B, C, and D
except for different amounts of catalysts and the amount of
the 2-allylphenol.
Adv. Synth. Catal. 2004, 346, 1375–1384
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Ratana Chanthateyanonth, Howard Alper
FULL PAPERS
[25] R. A. Dubois, (Dow Chemical Company), US Patent
4,567,281, 1986; Chem. Abstr. 1986, 105, 42649k.
[26] A. Patra, S. K. Misra, Magn. Reson. Chem. 1991, 29,
749–752.
[27] S. Abe, T. Nonaka, T. Fuchigami, J. Am. Chem. Soc.
1983, #105#103, 3630–3632.
[28] J. P. Nicolle, J. F. Hamon, M. Wakselman, Bull. Soc.
Chim. Fr. 1977, 83–88.
[29] D. D. Perrin, W. L. F. Armarego, Purification of Labora-
tory Chemicals, 3rd edn., Oxford, New York, Pergamon
Press, 1988.
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