New bis(fluoro-ponytailed) bipyridine ligands for Pd-catalyzed Heck reactions under fluorous biphasic catalysis condition

Article abstract of DOI:10.1016/j.tet.2006.12.053

Three highly fluorinated bipyridine derivatives (4,4′-bis(R_fCH₂OCH₂)-2,2′-bpy) {R_f=HCF₂(CF₂)₇ (1a), n-C₈F₁₇ (1b), n-C₁₀F₂₁ (1c)} have

Full text of DOI:10.1016/j.tet.2006.12.053

Tetrahedron 63 (2007) 2019–2023
New bis(fluoro-ponytailed) bipyridine ligands for Pd-catalyzed
Heck reactions under fluorous biphasic catalysis condition
a
a
a
b
Norman Lu,a, Yan-Chou Lin, Jeng-Yung Chen, Chi-Wen Fan and Ling-Kang Liu
*
aInstitute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 106, Taiwan
bInstitute of Chemistry, Academia Sinica, Taipei 115, Taiwan
Received 22 October 2006; revised 15 December 2006; accepted 18 December 2006
Available online 20 December 2006
Abstract—Three highly fluorinated bipyridine derivatives (4,40-bis(RfCH2OCH2)-2,20-bpy) {Rf¼HCF2(CF2)7 (1a), n-C8F17 (1b), n-C10F21
(1c)} have been synthesized using 4,40-bis(BrCH2)-2,20-bpy and the corresponding fluorinated alkoxides. The fluorine contents of ligands
1a–c are 58.3, 59.8, and 62.3%, respectively. Despite its high fluorine content, the ligand 1a with a –CF2H polar terminal group is more soluble
in organic solvents. The ligand 1b is a white solid and is still moderately soluble in CH2Cl2. The ligand 1c has a high fluorophilicity, the par-
tition ratio being 42:1 for the n-C8F18/CH2Cl2 system. The reaction of ligands 1a–c with [PdCl2(CH3CN)2] results in the novel Pd complexes
[PdCl2(4,40-bis-(RfCH2OCH2)-2,20-bpy)] where Rf¼HCF2(CF2)7 (2a), n-C8F17 (2b), n-C10F21 (2c), respectively. The Pd complex 2b is a pale
yellow solid, and has been tested unsatisfactorily for FBC. Insoluble in organic solvents, the Pd complex 2c dissolves only in fluorinated
solvents, for instance FC77, which is mainly n-C8F18. The novel Pd complex 2c has been tested as a catalyst in Heck reactions under a fluorous
biphasic catalysis condition. It was found that the Pd complex 2c, after an easy separation, keeps its catalytic activity (>90% yield), even after
seven runs. The TGA studies indicate that the Pd complexes 2a–c are stable up to 330 ꢀC.
Ó 2006 Elsevier Ltd. All rights reserved.
1. Introduction
complexes in Heck reactions, with palladacycle complexes
being proposed as the catalyst precursor. We have prepared
novel Pd complexes with bis(fluoro-ponytailed) bipyridines
as ligands, replacing fluorinated phosphines, for use in the
Heck reaction.18 The new, fluorinated bipyridine derivatives
are prepared from fluorinated alkanols.19
The concept of fluorous biphasic catalysis (FBC) was first
introduced by Horvath and Rabai in 1994. In the past de-
1
ꢀ
cade, this field has evolved rapidly.2 FBC has already been
applied to a variety of common organic reactions, e.g.,
hydroboration of alkenes,3 hydroformylation of alkenes,1,4
epoxidation of alkenes,5,6 Wacker oxidation of alkenes,7
palladium allylic alkylation,8 and oxidation of alcohols,9
aldehydes, thioethers, and alkanes.10,11
2. Results and discussion
2.1. Preparation of ligands 1a–c
The Heck reaction has been regarded as one of the most
important tools to create C–C bonds.12 However, Heck reac-
tions remain a tough challenge for chemists in designing
recyclable systems because the catalytic cycle is unstable,
responsive to various factors, and the reaction needs at least
three reagents13—electrophile, unsaturated olefin, and base.
Sinou et al.14 reported the use of perfluorinated phosphines
for Pd-catalyzed Heck reactions in which the Pd catalyst was
generated in situ, and its catalytic ability dropped to 70%
upon reusage in the third run. Curran et al. and Gladysz
and Rocaboy15–17 used the soluble fluorous palladacycle
Reported in this paper are our results on the successful appli-
cation of fluorinated bipyridine Pd6b complexes to catalyze
the Heck reaction under FBC,20,21 the yield, selectivity,
and recyclability all being satisfactory. 4,40-Bis(fluoro-pony-
tailed)-2,20-bpy ligands were prepared by making use of
fluorinated alkanols.6b As shown in Scheme 1, the fluori-
nated alkoxides RfCH2ONa {Rf¼HCF2(CF2)7 (a), n-C8F17
(b), n-C10F21 (c)} were obtained by stirring 30% CH3ONa/
CH3OH with the corresponding fluorinated alkanols. The
nucleophilic attack of a slight excess of RfCH2ONa on
4,40-bis-(BrCH2)-2,20-bpy22–24 gave rise to the synthesis
of a series of 4,40-bis(fluoro-ponytailed)-2,20-bpy ligands
1a–c. The reactions were clean with quantitative yields of
crude products, which could be easily purified as white
solids by sublimation.
Keywords: Fluorinated bipyridine; Fluorophilicity; Heck reaction; Fluorous
biphasic catalysis; TGA.
* Corresponding author. Tel.: +886 2 2771 2171x2417; fax: +886 2 2731
7174; e-mail: normanlu@ntut.edu.tw
0040–4020/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2006.12.053

2020
N. Lu et al. / Tetrahedron 63 (2007) 2019–2023
CH2Br
BrH2C
O
O
+
Rf
Rf
2 NaBr
65 °C
+
2 RfCH2ONa
CH3ONa
N
N
N
N
2 RfCH2OH
[Rf: HCF2(CF2)7 (1a), n-C8F17 (1b), n-C10F21 (1c)]
Scheme 1.
With a high fluorine content,25,26 the ligands 1a–c have been
measured for their solubility in organic solvents as well as
the fluorous solvent FC77, which is mainly n-C8F18, to give
distribution ratios shown in Table 1. Although 1a has a high
fluorine content, the presence of polar-CF2H group makes it
more soluble in FC77 than 1b and 1c. The ligand 1a is more
soluble in organic solvents than in FC77. On the other hand,
the partition ratio of ligand 1c, with the highest fluorine con-
tent among the ligands,25–27 has been recorded to be 1:42 and
w0.1:100 in the CH2Cl2/FC77 and DMF/FC77 systems, re-
spectively. It was preliminarily judged that the Pd complex
made from ligand 1c would be the choice among ligands
1a–c in the study of recyclable Heck reactions.
The Pd-catalyzed reaction of iodobenzene (3a) with methyl
acrylate (4) was selected to demonstrate the feasibility of
recycling use with Pd complex 2c as the catalyst under
DMF/FC77 biphasic system at 140 ꢀC for 6 h in each run,
as shown in Eq. 2. At the end of each run, the fluorous layer
containing Pd complex 2c was recycled to proceed to the
next. The products were quantified with GC analysis by
comparison to standards. The results are shown in Table 2.
The Heck reaction under FBC exhibited a good recyclability,
the yield being better than 88% after the seventh run. The
Heck reaction here also exhibited a 100% selectivity favor-
ing the trans product.
As Pd complex 2c could be prepared easily by stirring the
ligand 1c and [PdCl2(CH3CN)2] at room temperature, the
Heck reaction was also carried out with the Pd catalyst gen-
erated in situ. Thus, the ligand 1c and [PdCl2(CH3CN)2]
were charged into FC77 at a 1:1 molar ratio and the fluorous
phase was refluxed for 2 h before addition of DMF con-
taining substrates and base. At the end of the first run, the
fluorous layer was recovered and used for the second run.
Similar recovery procedure was undertaken during the later
runs. The yields of eight consecutive runs are summarized
in Table 3. The results were very similar to those in
Table 2. The Pd catalyst was effectively recovered and
reused for seven times before an observable drop in yields
took place.
Table 1. Distribution ratios of ligands 1a–c in different solvent systems
Ligand
CH2Cl2/FC77
DMF/FC77
(1a) (F%: 58.3)
(1b) (F%: 59.8)
(1c) (F%: 62.3)
100:0
1.07:1
1:42
100:0
1:4.5
<0.1:100
2.2. Preparation and catalytic activity of Pd complexes
2a–c
Three new Pd complexes, [PdCl2(4,40-bis(RfCH2OCH2)-
2,20-bpy)] where Rf¼HCF2(CF2)7 (2a), n-C8F17 (2b),
n-C10F21 (2c), were easily prepared from [PdCl2(CH3CN)2]
and the corresponding ligands 1a, 1b, and 1c, respectively,
as shown in Eq. 1. The bipyridine Pd complexes 2a–c have
a cis conformation, different from the bidentate pyridine
Pd complexes carrying the trans conformation reported
by Kawano et al.28 The reaction of equal amounts of
[PdCl2(CH3CN)2] and ligands proceeded smoothly, stirring
overnight in air at room temperature, followed by removal
of the solvents to yield the air and moisture stable Pd com-
plexes. The Pd complex 2a was not soluble in FC77. The
Pd complex 2b was slightly soluble in FC77. The Pd com-
plex 2b had been used in the Heck reaction under DMF/
FC77 biphasic condition. But we obtained a very low yield
during the second run, which can be attributed to the greater
solubility of 2b in DMF. In contrast to 2a and 2b, the Pd
complex 2c showed a very high reactivity and selectivity
during Heck reaction under FBC process.
Table 2. Recycling results of Heck reaction catalyzed by Pd complex 2c
under DMF/FC77 biphasic system
Cycle no.
Yielda
(%)
TON
Cycle no.
Yielda
(%)
TON
1
2
3
4
96.8
98.5
95.3
100.0
193.6
197.0
190.6
200.0
5
6
7
8
92.0
98.5
88.0
77.0
184.0
197.0
176.0
154.0
Note: reaction conditions: 140 ꢀC; 6 h; DMF (3 mL); FC77 (3 mL); iodo-
benzene (102 mg, 0.5 mmol), methyl acrylate (64.5 mg, 0.75 mmol), NEt3
(50.6 mg, 0.5 mmol), 0.5 mol % Pd complex 2c (3.64 mg); the two layers
separated using a separatory funnel at 0 ꢀC after each run. The fluorous layer
containing Pd complex 2c was washed with 2 mL DMF (or CH2Cl2) before
proceeding to the next run.
a
Based on GC yield.
O
O
Rf
Rf
CH3CN
NCCH3
Cl
O
O
Rf
Rf
r.t.
+
+
2 CH3CN
Pd
N
N
CH2Cl2 or FC77
(1)
N
N
Cl
Pd
Cl
[Rf = HCF2(CF2)7 (2a), n-C8F17 (2b), n-C10F21 (2c)]
Cl
[Rf = HCF2(CF2)7 (1a), n-C8F17 (1b), n-C10F21 (1c)]

N. Lu et al. / Tetrahedron 63 (2007) 2019–2023
2021
Table 3. Recycling results of Pd catalyst, generated in situ, in the Heck
reaction under DMF/FC77 biphasic system
Table 5. Recycling results of Pd complex 2c as the catalyst in the Heck
reaction under FBC system using 4-methoxy-iodobenzene as substrate
Cycle no.
Yielda (%)
TON
Cycle no.
Yielda (%)
TON
Cycle no.
Temp (ꢀC)
Time (h)
Yield (%)
TON
TOF
1
2
3
4
99
94
96
98
198
188
192
196
5
6
7
8
98
99
100
72
196
198
200
144
1
2
3
4
5
6
7
8
140
140
160
160
160
160
160
160
5
6
6
6
8
8
8
8
100.0
87.2
82.3
83.8
92.0
94.0
93.6
86.0
200.0
174.4
164.6
167.6
184.0
188.0
187.2
172.0
40.0
29.1
27.4
27.9
23.0
23.5
23.4
21.5
Note: reaction conditions: 140 ꢀC; 6 h; DMF (3 mL); FC77 (3 mL); iodo-
benzene (102 mg, 0.5 mmol), methyl acrylate (64.5 mg, 0.75 mmol), NEt3
(50.6 mg, 0.5 mmol), 0.5 mol % Pd catalyst {[PdCl2(CH3CN)2] (0.7 mg), li-
gand 1c (3.2 mg), initial in situ generation, 2 h}; the two layers separated
using a separatory funnel at 0 ꢀC after each run. The fluorous layer contain-
ing Pd catalyst was washed with 2 mL DMF (or CH2Cl2) before proceeding
to the next run.
a
releasing OMe group was expected to slow down the reac-
tions. As shown in Table 5, the recyclability of Heck reaction
was also successful, although a longer time and a higher tem-
perature were required. The yields dropped to <90% at the
second run with 6 h at 140 ꢀC. By increasing the temperature
(to 160 ꢀC) and/or time (to 8 h), the reusage of Pd complex
2c was still good, average yields being ca. 90% for eight con-
secutive runs.
Based on GC yield.
The data in Tables 2 and 3 suggest that the Pd complex 2c is
an effective and fluorous-phase soluble catalyst for the Heck
reaction under the DMF/FC77 biphasic system. The Pd com-
plex 2c is not only easily recyclable itself, but also easily
generated in situ from the component ligand 1c and the Pd
metal ion precursor.
2.4. Thermal studies
2.3. Substituted iodobenzene as substrate
The thermal studies (see Supplementary data) showed that
the ligands 1a–c were all stable up to 260 ꢀC. Surprisingly
the associated Pd complexes 2a–c were even more stable,
with decomposition temperatures being >330 ꢀC. The Pd
complexes of this type are not only air and moisture stable,
In order to see how applicable this Pd-catalyzed Heck reac-
tion is, two substituted iodobenzenes, p-IC6H4X [X¼NO2
(3b), OMe (3c)], were used as substrates for reactions under
FBC as shown in Eq. 2.
COOCH3
CH=CH
I
140-160°C
DMF/FC-77; NEt3; 3-8 h
CH2=CH
+
+
HNEt3I
(2)
COOCH3
X
X
X = H (3a), NO2 (3b), OMe (3c)
X = H (5a), NO2 (5b), OMe (5c)
4
The reaction of 3b with 4 was successfully carried out under
FBC. The results are listed in Table 4. The strong electron-
withdrawing NO2 group at the para position expedites the
reaction to a great extent. The first four runs could be com-
pleted in just 3 h at 140 ꢀC. For cycle nos. 5–8, the normal
time of 6 h was required for the reactions to complete. Over-
all, the recyclability was excellent with yields being 100%
for eight consecutive runs.
but also thermally robust. As a consequence, the Heck reac-
tion catalyzed by the novel Pd complex 2c should be feasible
at even higher temperature.
3. Conclusion
In summary, we have completed the synthesis of a new
series of 4,40-bis(fluoro-ponytailed)-2,20-bpy ligands, with
intrinsically high fluorine contents. From these ligands
we have also prepared the corresponding Pd complexes,
among which Pd complex 2c has been successfully used,
with good recyclability, in the Heck reaction under FBC.
The Pd complex 2c, either directly used or generated in situ,
can be employed to catalyze effectively the Heck reaction
and reused with good yields for eight consecutive runs. A
range of electron-withdrawing and electron-releasing sub-
strates, e.g., p-IC6H4X [X¼H (3a), NO2 (3b), OMe (3c)],
were tested in Heck reactions catalyzed by Pd complex
2c. Judged from the results in Tables 2, 4, and 5, the Pd
complex 2c is one of the best catalysts for use in Heck
reaction under FBC.
When p-IC6H4OMe (3c) was used as the substrate in Heck
reactions with Pd complex 2c as the catalyst, the electron-
Table 4. Recycling results of Pd complex 2c as the catalyst in the Heck
reaction under FBC system using 4-nitro-iodobenzene as substrate
Cycle no.
Temp (ꢀC)
Time (h)
Yield (%)
TON
TOF
1
2
3
4
5
6
7
8
140
140
140
140
140
140
140
140
3
3
3
3
6
6
6
6
100
100
100
100
100
100
100
100
200
200
200
200
200
200
200
200
66.7
66.7
66.7
66.7
33.3
33.3
33.3
33.3

2022
N. Lu et al. / Tetrahedron 63 (2007) 2019–2023
4. Experimental
bpy–CH2), 4.04 (4H, t, 3JHF¼13.5 Hz, CF2CH2); 19F NMR
(470.5 MHz, CDCl3) d ꢂ80.8 (3F), ꢂ119.3 (2F), ꢂ121.9
(6F), ꢂ122.7 (2F), ꢂ123.2 (2F), ꢂ126.1 (2F); 13C NMR
(113 MHz, CDCl3) d 73.0 (bpy–CH2), 67.7 (CH2CF2),
119.2, 121.9, 146.9, 149.6, 156.1 (bpy), 108.0–119.0
(C8F17); GC/MS (m/z; EI): 632 (M+ꢂOCHC8F17), 198
(C5H3NCH2C5H3NCH2O+), 183 (C5H3NCH2C5H3NCH+3),
91 (C5H3NCH+2); FTIR (cmꢂ1): 1602.0, 1559.8, 1465.0
(nbpy, m), 1203.7, 1144.7 (nCF2, vs); mp: 113–115 ꢀC.
4.1. General procedures
Gas chromatographic/mass spectrometric data were obtained
using an Agilent 6890 Series gas chromatograph with a series
5973 mass selective detector. The reaction was monitored
with an HP 6890 GC using a 30 mꢁ0.250 mm HP-1 capillary
column with a 0.25 mm stationary phase film thickness.
Temperature program was a 2 min hold at 50 ꢀC and then
taken to 260 ꢀC at 10 ꢀC/min and held for 12 min at
260 ꢀC. The flow rate was 1 mL/min and splitless. Infrared
spectra were obtained on a Perkin Elmer RX I FT-IR Spec-
trometer. NMR spectra were recorded on Bruker AM 500
and Joel AM 200 spectrometers using 5 mm sample tubes.
CD3OD, CD2Cl2, CD3Cl, and deuterated Me2SO were the
4.3.3. Compound 1c. NMR data were collected in CDCl3
at 60 ꢀC to increase the solubility. Yield (sublimed) 65%;
3
1H NMR (500 MHz, CDCl3) d 8.69 (2H, d, JHH¼5.1 Hz,
3
H6), 8.40 (2H, s, H3), 7.38 (2H, d, JHH¼4.2 Hz, H5), 4.80
3
(4H, s, bpy–CH2), 4.06 (4H, t, JHF¼13.3 Hz, CF2CH2);
19F NMR (470.5 MHz, CDCl3) d ꢂ80.7 (3F), ꢂ119.3
(2F), ꢂ121.7 (6F), ꢂ121.8 (4F), ꢂ122.6 (2F), ꢂ123.1
(2F), ꢂ126.0 (2F); 13C NMR (113 MHz, CDCl3) d 73.1
(bpy–CH2), 68.1 (CH2CF2), 119.8, 122.2, 144.7, 149.4,
154.1 (bpy), 105.5–116.2 (C10F21); GC/MS (m/z; EI): 732
(M+ꢂOCHC10F21), 198 (C5H3NCH2C5H3NCH2O+), 183
(C5H3NCH2C5H3NCH+3), 91 (C5H3NCH2+); FTIR (cmꢂ1):
1602.4, 1561.7 (nbpy, m), 1215.0, 1150.5 (nCF2, vs); mp:
140–142 ꢀC.
1
references for both H and 13C NMR spectra and FreonÒ
11 (CFCl3) was the reference for 19F NMR spectra. Thermo-
gravimetric analyses (TGA) were performed on a TA Instru-
ments TGA51.
4.2. Starting materials
Chemicals, reagents, and solvents employed were commer-
cially available and used as received. HCF2(CF2)7CH2OH
was obtained from Daikin Taiwan. C8F17CH2OH and
C10F21CH2OH were purchased from Aldrich and SynQuest.
4.4. Preparation of Pd complexes 2a–c where
Rf¼HCF2(CF2)7 (a), n-C8F17 (b), n-C10F21 (c)
4.3. Preparation of 4,40-bis(RfCH2OCH2)-2,20-bpy 1a–c
where Rf¼HCF2(CF2)7 (a), n-C8F17 (b), n-C10F21 (c)
Equimolar [PdCl2(CH3CN)2] (134.9 mg, 0.52 mmol) and
respective ligands 1a–c (0.52 mmol) in different reactions
were charged into a round-bottomed flask, and CH2Cl2
(3 mL) added as solvent. The color of the solution changed
from red to yellow after mixing for several minutes. The so-
lution was further stirred at room temperature for 24 h before
the solvents and volatiles were removed under vacuum. The
resulting yellow solids were collected as spectroscopically
pure products.
General procedure: 30% CH3ONa/CH3OH (1.1 g) and
RfCH2OH (6.0 mmol) were charged into a round-bottomed
flask, then continuously stirred under N2 atmosphere at
65 ꢀC for 4 h before CH3OH was vacuum removed to drive
the reaction to the fluorinated alkoxide side. The resultant
fluorinated alkoxide (6.0 mmol) was then dissolved in 20 mL
of dry CH3CN (or HFE 7100), and 4,40-bis(BrCH2)-2,20-
bpy (5.8 mmol) was added. The mixture was refluxed for
4 h, and the completion of the reaction was checked by
sampling the reaction mixtures and analyzing the aliquots
with GC/MS. The product was purified by vacuum sublima-
tion to obtain white solids. The vacuum level was 0.1 Torr,
and the sublimation temperature was 50 ꢀC above its mp.
4.4.1. Compound 2a. Yield 96%; 1H NMR (500 MHz,
3
Me2SO-d) d 9.08 (2H, d, JHH¼5.8 Hz, H6), 8.34 (2H, s,
3
H3), 7.73 (2H, dd, JHH¼5.8 Hz, H5), 7.19 (2H, tt,
3
2JHF¼50.3 Hz, JHF¼5.3 Hz, CF2H), 4.96 (4H, s, bpy–
3
CH2), 4.41 (4H, t, JHF¼14.6 Hz, CF2CH2); 19F NMR
(470.5 MHz, Me2SO-d) d ꢂ119.1 (s, 2F, CH2CF2), ꢂ121.9
(s, 6F), ꢂ122.9 (s, 4F), ꢂ128.7 (s, 2F, HCF2CF2), ꢂ138.5
(d, 2F, 2JHF¼52 Hz, HCF2); 13C NMR (113 MHz, Me2SO-
d) d 71.0 (bpy–CH2), 66.8 (CH2CF2), 120.5, 124.2, 149.3,
151.6, 155.6 (bpy), 105.0–116.4 (CF2)8; FTIR (cmꢂ1):
1654.0, 1559.9 (nbpy, m), 1209.9, 1146.9 (nCF2, vs);
HRMS (FAB): (M+; m/z¼) C30N2H16F32O2Pd35Cl2 calcd
1219.9113, found 1219.9169; C30N2H16F32O2Pd35Cl37Cl
calcd 1221.9041, found 1221.9041; C30N2H16F32O2Pd37Cl2
calcd 1223.9054, found 1223.9009.
4.3.1. Compound 1a. Yield (sublimed) 85%; 1H NMR
3
(500 MHz, CDCl3) d 8.69 (2H, d, JHH¼4.5 Hz, H6), 8.33
3
(2H, s, H3), 7.36 (2H, d, JHH¼4.5 Hz, H5), 6.03 (1H, tt,
3
2JHF¼51.9 Hz, JHF¼5.5 Hz, CF2H), 4.78 (4H, s, bpy–
3
CH2), 4.04 (4H, t, JHF¼13.7 Hz, CF2CH2); 19F NMR
(470.5 MHz, CDCl3) d ꢂ119 (s, 2F, CH2CF2), ꢂ121 (s,
6F), ꢂ123 (s, 4F), ꢂ129 (s, 2F, HCF2CF2–), ꢂ137 (d, 2F,
2JHF¼52 Hz, HCF2–); 13C NMR (113 MHz, CDCl3)
d 72.4 (bpy–CH2), 67.1 (CH2CF2), 118.9, 122.5, 147.9,
149.9, 155.7 (bpy), 105.0–116.3 (CF2)8; GC/MS (m/z; EI):
614 (M+ꢂOCH2C8F16), 198 (C5H3NCH2C5H3NCH2O+),
183 (C5H3NCH2C5H3NCH+3), 91 (C5H3NCH2+); FTIR
(cmꢂ1): 1595.6, 1558.3 (nbpy, m), 1208.3, 1140.3 (nCF2,
vs); mp: 86–88 ꢀC.
4.4.2. Compound 2b. NMR data were collected in DMF-d
at 90 ꢀC because of solubility. Yield 96%; 1H NMR
3
(500 MHz, DMF-d) d 9.29 (2H, d, JHH¼5.9 Hz, H6), 8.48
3
(2H, s, H3), 7.82 (2H, d, JHH¼5.9 Hz, H5), 5.08 (4H, s,
3
bpy–CH2), 4.47 (4H, t, JHF¼14.3 Hz, C8F17–CH2);
19F NMR (470.5 MHz, DMF-d) d ꢂ80.9 (3F), ꢂ119.1
(2F), ꢂ121.3 (6F), ꢂ122.1 (2F), ꢂ122.7 (2F), ꢂ125.5
(2F); 13C NMR (113 MHz, DMF-d) d 72.4 (bpy–CH2),
68.3 (CH2CF2), 121.7, 125.3, 15.6, 153.1, 157.2 (bpy),
4.3.2. Compound 1b. Yield (sublimed) 80%; 1H NMR
3
(500 MHz, CDCl3) d 8.67 (2H, d, JHH¼4.9 Hz, H6), 8.40
3
(2H, s, H3), 7.34 (2H, d, JHH¼4.9 Hz, H5), 4.77 (4H, s,

N. Lu et al. / Tetrahedron 63 (2007) 2019–2023
2023
105.0–120.0 (C8F17); FTIR (cmꢂ1): 1622.9, 1558.8, 1436.9
Supplementary data
(nbpy, m), 1203.7, 1148.4 (nCF2, vs); HRMS (FAB): (M+;
m/z¼) C30N2H14F34O2Pd35Cl2 calcd 1255.8924, found
1255.8920; C30N2H14F34O2Pd35Cl37Cl calcd 1257.8928,
TGA data for the three ligands 1a–c and the three Pd com-
plexes 2a–c. Supplementary data associated with this article
can be found in the online version, at doi:10.1016/j.tet.2006.
12.053.
found 1257.8954;
1259.8899, found 1259.8844.
C30N2H14F34O2Pd37Cl2
calcd
4.4.3. Compound 2c. NMR data were collected in DMF-d
at 90 ꢀC because of solubility. Yield 96%; 1H NMR
References and notes
3
(500 MHz, DMF-d) d 9.29 (2H, d, JHH¼5.8 Hz, H6), 8.47
(2H, s, H3), 7.81 (2H, d, 3JHH¼5.8 Hz, H5), 5.08 (4H, s, bpy–
ꢀ
1. Horvath, I. T.; Rabai, J. Science 1994, 266, 72–75.
2. Freemantle, M. Chem. Eng. News August 15, 2005, 83.
ꢀ
3. (a) Juliette, J. J. J.; Horvath, I. T.; Gladysz, J. A. Angew. Chem.,
Int. Ed. 1997, 36, 1610–1612; (b) Juliette, J. J. J.; Rutherford,
3
CH2), 4.47 (4H, t, JHF¼14.6 Hz, C10F21–CH2); 19F NMR
(470.5 MHz, DMF-d) d ꢂ80.9 (3F), ꢂ121.0 (4F), ꢂ121.31
(6F), ꢂ122.1 (2F), ꢂ122.7 (2F), ꢂ125.5 (2F); 13C NMR
(113 MHz, DMF-d) d 74.2 (bpy–CH2), 68.2 (CH2CF2), 120.3,
124.5, 140.9, 151.8, 157.3 (bpy), 105.0–116.0 (C10F21); FTIR
(cmꢂ1): 1622.9, 1558.3 (nbpy, m), 1208.3, 1150.5 (nCF2, vs);
HRMS (FAB): (M+; m/z¼) C34N2H14F42O2Pd35Cl2 calcd
1455.8869, found 1455.8842; C34N2H14F42O2Pd35Cl37Cl
calcd 1457.8767, found 1457.8741; C34N2H14F42O2Pd37Cl2
calcd 1459.8737, found 1459.8734.
ꢀ
D.; Horvath, I. T.; Gladysz, J. A. J. Am. Chem. Soc. 1999,
121, 2696–2704.
ꢀ
4. Horvath, I. T.; Kiss, G.; Cook, R. A.; Bond, J. E.; Stevens, P. A.;
Rabai, J.; Mozeleski, E. J. J. Am. Chem. Soc. 1998, 120, 3133–
3143.
5. Klement, I.; L€utjens, H.; Knochel, P. Angew. Chem., Int. Ed.
1997, 36, 1454–1456.
6. (a) Pozzi, G.; Cinato, F.; Montanari, S. Chem. Commun. 1998,
877–878; (b) Quici, S.; Cavazzini, M.; Ceragioli, S.;
Montanari, F.; Pozzi, G. Tetrahedron Lett. 1999, 40, 3647–
3650.
ꢁ
4.5. Recycling studies of the Heck reaction with Pd
complex 2c as catalyst
7. Betzemeier, B.; Lhermitte, F.; Knochel, P. Tetrahedron Lett.
1998, 39, 6667–6670.
8. Kling, R.; Sinou, D.; Pozzi, G.; Chouplin, A.; Quignard, F.;
Busch, S.; Kainz, S.; Koch, D.; Leitner, W. Tetrahedron Lett.
1998, 39, 9439–9442.
9. Betzemeier, B.; Cavazzini, M.; Quici, S.; Knochel, P.
Tetrahedron Lett. 2000, 41, 4343–4346.
10. Vincent, J. M.; Rabion, A.; Yachandra, V. K.; Fish, R. H.
Angew. Chem., Int. Ed. 1997, 36, 2346–2349.
11. Pozzi, G.; Cavazzini, M.; Quici, S.; Fontana, S. Tetrahedron
Lett. 1997, 38, 7605–7608.
4.5.1. Heck reaction with C6H5I as the substrate. Under
the fluorous biphasic system, the vessel was charged with
DMF (3 mL), FC77 (3 mL), C6H5I (102 mg, 0.50 mmol),
H2C]CHCO2Me (64.5 mg, 0.75 mmol), NEt3 (50.6 mg,
0.50 mmol), and the 0.5 mol % Pd complex {2c (3.64 mg)
or components [PdCl2(CH3CN)2] (0.7 mg), ligand 1c
(3.2 mg)}. The reaction mixture was refluxed at 140 ꢀC for
6 h before the reaction was stopped and the two layers sep-
arated using a separatory funnel at 0 ꢀC. The FC77 fraction
was retained for recycling experiments.
12. Alonso, F.; Beletskaya, I. P.; Yus, M. Tetrahedron 2005, 61,
12058–12064.
13. Beletskaya, I. P.; Cheprakov, A. V. Chem. Rev. 2000, 100,
3009–3066.
14. Moineau, J.; Pozzi, G.; Quici, S.; Sinou, D. Tetrahedron Lett.
1999, 40, 7683–7686.
15. Curran, D. P.; Fischer, K.; Moura-Letts, G. Synlett 2004, 1379–
1382.
16. Rocaboy, C.; Gladysz, J. A. New J. Chem. 2003, 27, 39–49.
17. Rocaboy, C.; Gladysz, J. A. Org. Lett. 2002, 4, 1993–1996.
18. Wende, M.; Seidel, F.; Gladysz, J. A. J. Fluorine Chem. 2003,
124, 45–54.
4.5.2. Heck reaction with p-IC6H4NO2 as the substrate.
In a typical run, the reaction vessel was charged with
p-IC6H4NO2 (123.5 mg, 0.50 mmol), H2C]CHCO2Me
(64.5 mg, 0.75 mmol), NEt3 (50.6 mg, 0.50 mmol), and the
Pd complex 2c (0.5 mol %, 3.64 mg) or the recovered Pd
catalyst after each run. Then the reaction mixture was set
to reflux in DMF/FC77 (2 mL each), at 140 ꢀC for 3–6 h
before the reaction was stopped and the two layers separated
using a separatory funnel at 0 ꢀC. The FC77 fraction was
retained for recycling experiments.
4.5.3. Heck reaction with p-IC6H4OMe as the substrate.
In a typical run, the reaction vessel was charged with
p-IC6H4OMe (117 mg, 0.50 mmol), H2C]CHCO2Me
(64.5 mg, 0.75 mmol), NEt3 (50.6 mg, 0.50 mmol), and the
Pd complex 2c (0.5 mol %, 3.64 mg) or the recovered Pd
catalyst after each run. Then the reaction mixture was set
to reflux in DMF/FC77 (2 mL each), at 140–160 ꢀC for a
period of 5–8 h before the reaction was stopped and the
two layers separated using a separatory funnel at 0 ꢀC. The
FC77 fraction was then used for recycling experiments.
19. Howell, J. L.; Lu, N.; Friesen, C. M. J. Fluorine Chem. 2005,
126, 281–288.
20. Hope, E. G.; Stuart, A. M. J. Fluorine Chem. 1999, 100, 75–83.
ꢀ
21. Horvath, I. T. Acc. Chem. Res. 1998, 31, 641–650.
22. Ciana, L. D.; Dressick, W. J. J. Heterocycl. Chem. 1990, 27,
163–165.
23. Oki, A. R.; Morgan, R. J. Synth. Commun. 1995, 25, 4093–4097.
24. Will, G.; Boschloo, G.; Rao, S. N.; Fitzmaurice, D. J. Phys.
Chem. B 1999, 103, 8067–8079.
25. Curran, D. P.; Luo, Z. J. Am. Chem. Soc. 1999, 121, 9069–9072.
26. Studer, A.; Jeger, P.; Wipf, P.; Curran, D. P. J. Org. Chem. 1997,
62, 2917–2924.
Acknowledgements
27. Yao, Q.; Zhang, Y. J. Am. Chem. Soc. 2004, 126, 74–75.
28. Kawano, T.; Shinomaru, T.; Ueda, I. Org. Lett. 2002, 4, 2545–
2547.
The authors thank the National Research Council in Taiwan
for the financial support (NSC 94-2113-M-027-003).