High fluorine content bis(fluoro-ponytailed) bipyridine palladium complexes as catalyst for Mizoroki-Heck reactions under fluorous biphasic catalysis conditions

Article abstract of DOI:10.1002/jccs.200800014

Two highly fluorinated bipyridine derivatives, (4,4′-bis(R _fCH₂OCH₂)-2,2′-bpy) {R_f = n-C₁₀F₂₁ (1a), n-C₁₀F₂₃ (1b)}, have been synthesized starting from 4,4′-bis(BrCH₂)-2,2′-bpy and the corresponding fluorinated alkoxides. The fluorine contents of ligands 1a-b are 62.3% and 63.3%, respectively, both being white solids, virtually insoluble in CH₂Cl₂ or DMF and highly fluorophilic with a partition ratio between DMF and n-C₈F₁₈ less than 1:1000. The reaction of ligands 1a-b with [Pd(CH₃CN)₂Cl ₂] results in novel Pd complexes [PdCl₂(4,4′-bis- (R_fCH₂OCH₂)-2,2′-bpy)] where R _f = n-C₁₀F₂₁ (2a), n-C₁₀F ₂₃ (2b), respectively. The Pd complexes 2a-b are pale yellow solids, soluble only in fluorinated solvents. The Pd complexes 2a-b have been satisfactorily tested for Mizoroki-Heck arylation under fluorous biphasic catalysis conditions in that the Pd complexes 2a-b are easily recovered and maintain good catalytic activity after 8 consecutive cycles (> 90% yield). The TGA studies indicate that the Pd complexes 2a-b are thermally stable up to 300°C.

Full text of DOI:10.1002/jccs.200800014

Journal of the Chinese Chemical Society, 2008, 55, 89-96
89
High Fluorine Content Bis(fluoro-ponytailed) Bipyridine Palladium
Complexes as Catalyst for Mizoroki-Heck Reactions under Fluorous
Biphasic Catalysis Conditions
Norman Lua* (
), Shih-Chieh Chena (
), Yan-Chou Lina (
),
Yao-Yi Chenga (
) and Ling-Kang Liub* (
)
aInstitute of Organic and Polymeric Materials, National Taipei University of Technology,
Taipei 106, Taiwan, R.O.C.
bInstitute of Chemistry, Academia Sinica, Taipei 115, Taiwan, R.O.C.
Two highly fluorinated bipyridine derivatives, (4,4¢-bis(RfCH2OCH2)-2,2¢-bpy) {Rf = n-C10F21 (1a),
n-C10F23 (1b)}, have been synthesized starting from 4,4¢-bis(BrCH2)-2,2¢-bpy and the corresponding fluo-
rinated alkoxides. The fluorine contents of ligands 1a-b are 62.3% and 63.3%, respectively, both being
white solids, virtually insoluble in CH2Cl2 or DMF and highly fluorophilic with a partition ratio between
DMF and n-C8F18 less than 1:1000. The reaction of ligands 1a-b with [Pd(CH3CN)2Cl2] results in novel
Pd complexes [PdCl2(4,4¢-bis-(RfCH2OCH2)-2,2¢-bpy)] where Rf = n-C10F21 (2a), n-C10F23 (2b), respec-
tively. The Pd complexes 2a-b are pale yellow solids, soluble only in fluorinated solvents. The Pd com-
plexes 2a-b have been satisfactorily tested for Mizoroki-Heck arylation under fluorous biphasic catalysis
conditions in that the Pd complexes 2a-b are easily recovered and maintain good catalytic activity after 8
consecutive cycles (> 90% yield). The TGA studies indicate that the Pd complexes 2a-b are thermally sta-
ble up to 300 °C.
Keywords: Biphasic catalysis; Fluorinated ligand; Mizoroki-Heck reaction; Homogeneous catal-
ysis.
INTRODUCTION
Horvath and Rabai introduced the concept of fluo-
ple, the incorporation of highly fluorous polytails on 2,2¢-
bpy would make the ligand more soluble in fluorinated sol-
vents and less so in organic solvents. In the literature, the
Pd complexes are amongst the most popular transition
metal compounds as catalysts.12 Thus, the combination of a
Pd metal center with the fluorous-ponytailed 2,2¢-bpy lig-
ands should result in a rich chemistry for FBC applica-
tions.13,14 The Mizoroki-Heck (MH) type reaction has been
chosen as a study model to test on recycling of the novel Pd
complexes, taking advantage of its facileness to create a
C-C bond.15 However, the MH reactions remain a difficult
challenge for chemists in designing the recyclable systems
because the catalytic cycle is responsive to various vari-
ables and is in optimum need of 3 reagents:16 electrophile,
unsaturated olefin, and base. Sinou et al.13 reported the use
of perfluorinated phosphines in the recycling study of Pd-
catalyzed MH reactions in that the Pd catalyst was gener-
ated in situ, and its catalytic activity dropped to 70% in the
3rd run. Curran et al. and Gladysz et al.17-19 used the soluble
rous biphasic catalysis (FBC) in 1994.1 The field has
evolved rapidly from that time on2 and FBC has become
one of the important strategies in the design and reusage of
homogeneous metal catalysts. Exploiting the immiscibility
of organic and fluorous solvents, FBC has found good ap-
plication to a variety of common organic reactions, e.g.
alkene hydroboration,3 alkene hydroformylation,1,4 alkene
epoxidation,5,6 Wacker oxidation of alkenes,7 palladium al-
lylic alkylation,8 and oxidation of alcohols,9 aldehydes,
thioethers and alkanes.10,11
As a common bidentate ligand, 2,2¢-bipyridine (2,2¢-
bpy) upon coordination to the metal center is known to
maintain the bonding geometry of the metal center even
when the metal center is reduced or oxidized. It is also
known that modifying a molecule with fluorous segments
would alter its physical properties to an extent. For exam-
* Corresponding author. E-mail: normanlu@ntut.edu.tw (Norman Lu); liuu@chem.sinica.edu.tw (Ling-Kang Liu)

90 J. Chin. Chem. Soc., Vol. 55, No. 1, 2008
Lu et al.
fluorous palladacycle complexes in Heck reactions, with
palladacycle complexes being proposed as the nanoparticle
catalyst precursor. In particular, de Vries et al.20 proposed
the ligand-free Pd colloids as catalyst precursor for the
Heck reactions.
Scheme I
Reported here are the syntheses of highly fluorinated
2,2¢-bpy ligands and their coordination to Pd metal centers
to form novel complexes for employment in the MH aryla-
tion of a,b-unsaturated carboxylic acid/ester under FBC.21
RESULTS AND DISCUSSION
Synthesis of ligands 1a-c and Pd complexes 2a-c
The preparation of fluorous-ponytailed 2,2¢-bpy lig-
ands started from deprotonation of readily available fluo-
rous alkanols, RfCH2OH, where Rf = n-C10F21 (a), n-C10F23
(b) and CF3CF2CF2CH2 (c). Fluorous alkanols, RfCH2OH,
were treated with CH3ONa solution (30% in CH3OH) to
give the corresponding alkoxides. The alkoxides were iso-
lated and then reacted with 4,4¢-bis(BrCH2)-2,2¢-bpy22-24 to
give rise to [4,4¢-bis(RfCH2OCH2)-2,2¢-bpy)] (1a-c). Early
preparation reported by Pozzi et al.25 resulted in mixtures
of mono- and bis-substituted bpy, presumably the alkox-
ides were generated in situ without isolation during their
preparations. The ligands 1a-b have fluorine contents of
62.3% and 63.3%, respectively, and the ligand 1c has a flu-
orine content of 45.9% only. The partition ratios of 1a-c in
the CH2Cl2/FC77 system are 1:42, 1:70 and 100:~0, re-
spectively. And the partition ratios of 1a-b in DMF/FC77
system are small (approx. 1:1000). Yet that of 1c is insolu-
ble in FC77. As shown in Scheme I, equal moles of
[Pd(CH3CN)2Cl2] and fluorous bpy ligand 1a-c were stir-
red in a co-solvent of CH2Cl2 and HFE-7100 at room tem-
perature, yielding the Pd complexes 2a-c, [PdCl2(4,4¢-
bis(RfCH2OCH2)-2,2¢-bpy)], that are pale yellow solids,
and air and moisture stable.26 With the exception of Pd
complex 2c, complexes 2a-b are insoluble in organic sol-
vents and only soluble in fluorinated solvents.
As shown in Scheme II, the Pd-complexes 2a-b were
employed as the catalyst precursors in the MH arylation of
a,b-unsaturated carboxylic acid/ester under FBC.27 Pd
complex 2c was not tested as judged from the less favor-
able partition ratio in the DMF/FC77 system. The MH aryl-
ation of a,b-unsaturated carboxylic acid was expected to
be more difficult than that of a,b-unsaturated methylcar-
boxylate because of the presence of a more reactive acid
group in the former.
MH Arylation of a,b-Unsaturated Carboxylic Acid
under FBC
The Pd-catalyzed MH arylation of H2C=CHCO2H
was selected to demonstrate the feasibility of recycling us-
age of the catalyst in the DMF/FC77 biphasic system. The
Scheme II

Mizoroki-Heck Reactions under Fluorous Biphasic Catalysis
J. Chin. Chem. Soc., Vol. 55, No. 1, 2008 91
reaction vessel was first charged with the aryl iodide and
H2C=CHCO2H, followed in sequence by NEt3 and the
Pd-catalyst precursor (1 mol %). Then the reaction mixture
was stirred at 120-140 °C for 3-6 h. At the end of each cy-
cle, the fluorous layer was separated from the DMF layer,
and the fluorous layer was charged with the same reactants
and base to proceed to the next run. The products in the
DMF layer were quantified with GC analysis by compari-
son to an internal standard (NMP). The results of MH
arylation exhibited a 100% selectivity of the trans product.
Table 2. FBC recycling results of complex 2a as catalyst in the
MH arylation of 4a and 3a
Cycle No. Time (h) Temp (°C) Yielda (%) TON
TOF
1
2
3
4
5
6
7
8
3
5
5
6
6
6
6
6
120
140
140
140
140
140
140
140
100
100
100
100
100
100
088
095
100
100
100
100
100
100
088
095
33.3
20.0
20.0
16.6
16.6
16.6
14.7
15.8
Note: Reaction conditions: DMF (3 mL); FC77 (3 mL); 3a (0.5
mmol, 102.0 mg), 4a (1.0 mmol, 71.0 mg), NEt3 (2.0 mmol,
204.0 mg), 1 mol % Pd complex 2a (7.3 mg). After each cycle,
the DMF and FC77 layers were separated at 0 °C using a
separatory funnel. The FC77 layer was washed with 2 mL DMF
(or CH2Cl2) before proceeding to the next cycle.
Catalysis of Complex 2a
In agreement with our earlier study,21 the aryl com-
pound with para NO2 substituent exhibited a greater rate
than the parent aryl compound. The MH reaction of 3b with
4a was successfully catalyzed by the fluorous layer (con-
taining Pd complex 2a) with good results of recycling 8
times including the initial run, as shown in Table 1. Simi-
larly the Pd complex 2a catalyzed MH arylation of 4a with
3a as the substrate also worked, the Pd complex 2a being
reused 8 times with high yields, too, as shown in Table 2.
The data indicated that indeed the high fluorous content Pd
complex 2a was a good catalyst for use in recycling MH
arylations of 4a and aryl iodides, and the interferences of
the acid group seemed minimal.
a Based on GC yield (internal standard is NMP).
Table 3. FBC recycling results of complex 2b as catalyst in MH
arylation of 4a and 3b
Cycle No. Time (h) Temp (°C) Yielda (%) TON
TOF
1
2
3
4
5
6
7
8
3
5
5
6
6
6
6
6
120
140
140
140
140
140
140
140
100
100
098
100
100
100
100
100
100
100
098
100
100
100
100
100
33.3
20.0
19.6
16.6
16.6
16.6
16.6
16.6
Catalysis of Complex 2b
When Pd complex 2b was used to catalyze the MH re-
action of 3b with 4a, the recycling results showed also al-
Note: Reaction conditions: DMF (3 mL); FC77 (3 mL); 3b (0.5
mmol, 124.5 mg), 4a (1.0 mmol, 71.0 mg), NEt3 (2.0 mmol,
204.0 mg), 1 mol % Pd complex 2b (7.8 mg). After each cycle,
the DMF and FC77 layers were separated at 0 °C using a
separatory funnel. The FC77 layer was washed with 2 mL DMF
(or CH2Cl2) before proceeding to the next cycle.
Table 1. FBC recycling results of Pd complex 2a as catalyst in
MH arylation of 4a and 3b
a Based on GC yield (internal standard is NMP).
Cycle No. Time (h) Temp (°C) Yielda (%) TON
TOF
1
2
3
4
5
6
7
8
3
5
5
5
5
6
6
6
120
120
140
140
140
140
140
140
100.0
100.0
100.0
099.5
100.0
100.0
100.0
099.0
100.0
100.0
100.0
099.5
100.0
100.0
100.0
099.0
33.3
20.0
20.0
19.9
20.0
16.7
16.7
16.5
most 100% yields and an excellent recyclability for 8 times
(Table 3). The MH reaction of 3a and 4a was also satisfac-
torily catalyzed, with results summarized in Table 4. The
data in Table 4 were very comparable to those in Table 3,
with slightly lower TOFs, especially for cycle no. 4. The
overall results indicated a good recyclability of Pd complex
2b, too, for 8 times of reusage.
Note: Reaction conditions: DMF (3 mL); FC77 (3 mL); 3b (0.5
mmol, 124.5 mg), 4a (1 mmol, 71.0 mg), NEt3 (1.5 mmol, 152.0
mg), 1 mol % Pd complex 2a (7.3 mg). After each cycle, the
DMF and FC77 layers were separated at 0 °C using a separatory
funnel. The FC77 layer was washed with 2 mL DMF (or CH2Cl2)
before proceeding to the next cycle.
MH Arylation of a,b-Unsaturated Ester under FBC
When H2C=CHCO2Me was used as the olefin in the
recycling experiments of MH arylation, the reaction pro-
ceeded more smoothly as expected, because the methyl es-
a Based on GC yield (internal standard is NMP).

92 J. Chin. Chem. Soc., Vol. 55, No. 1, 2008
Lu et al.
Table 4. FBC recycling results of complex 2b as catalyst in MH
arylation of 4a and 3a
Table 6. FBC recycling results of complex 2a as catalyst in MH
arylation of 4b and 3b
Cycle No. Time (h) Temp (°C) Yielda (%) TON
TOF
Cycle No. Time (h) Temp (°C) Yielda (%) TON
TOF
1
2
3
4
5
6
7
8
3
5
5
6
6
6
6
6
120
140
140
140
140
140
140
140
100
094
084
098
098
099
>99
>99
100
094
084
098
098
099
>99
>99
33.3
18.8
16.8
16.3
16.3
16.5
>16.5
>16.5
1
2
3
4
5
6
7
8
3
3
3
3
6
6
6
6
140
140
140
140
140
140
140
140
100
100
100
100
100
100
100
100
200
200
200
200
200
200
200
200
66.6
66.6
66.6
66.6
33.3
33.3
33.3
33.3
Note: Reaction conditions: DMF (3 mL); FC77 (3 mL); 3a (0.5
mmol, 102.0 mg), 4a (1 mmol, 71.0 mg), NEt3 (1.5 mmol, 152.0
mg), 1 mol % Pd complex 2b (7.8 mg). After each cycle, the
DMF and FC77 layers were separated at 0 °C using a separatory
funnel. The FC77 layer was washed with 2 mL DMF (or CH2Cl2)
before proceeding to the next cycle.
Note: Reaction conditions: DMF (3 mL); FC77 (3 mL); 3b (0.5
mmol, 124.5 mg), 4b (1.0 mmol, 81.3 mg), NEt3 (1.5 mmol, 152
mg), 0.5 mol % Pd complex 2a (3.64 mg). After each cycle, the
DMF and FC77 layers were separated at 0 °C using a separatory
funnel. The FC77 layer was washed with 2 mL DMF (or CH2Cl2)
before proceeding to the next cycle.
a Based on GC yield (internal standard is NMP).
a Based on GC yield (internal standard is NMP).
ter group of H2C=CHCO2Me was more stable than the acid
group of H2C=CHCO2H. At the end of each cycle, the fluo-
rous layer containing Pd complex 2a-b was separated from
the DMF layer and was recycled to proceed to the next run.
The products were quantified with GC analysis by compar-
ison to an internal standard (NMP). The results of MH
arylation here showed a 100% selectivity favoring the
trans isomer.
recyclability, the average yield being greater than 96.5%
for 8 cycles.
In order to determine the electronic effect for substi-
tuted iodobenzenes on this Pd-catalyzed MH reaction, both
3b and p-MeOC6H4I (3c) were also used as substrates. The
results for the 3b reaction are listed in Table 6. The strongly
electron-withdrawing NO2 group at the para position expe-
dites the reaction to a greater extent. During the first 4 cy-
cles the arylations could be completed in just 3 h at 140 °C,
and during the later cycles in 6 h. Overall, the recyclability
was excellent with yields being 100% for a total of 8 con-
secutive cycles.
Catalysis by Complex 2a
As shown in Table 5, the MH reaction of 3a and 4b
catalyzed by Pd complex 2a under FBC exhibited a good
When 3c was used as the substrate in MH arylation
with Pd complex 2a as the catalyst, the electron-releasing
OMe group slowed down the reactions (see Table 7). None-
theless, the recyclability could be demonstrated, only with
a longer time and a higher temperature. The yields dropped
to <90% beginning at the 2nd cycle at 140 °C in 6 h. By in-
creasing the temperature to 160 °C and time to 8 h, the recy-
cling usage of Pd complex 2a gave average yields of approx.
90% for 8 consecutive cycles.
Table 5. FBC recycling results of complex 2a as catalyst in MH
arylation of 4b and 3a
Cycle No. Time (h) Temp (°C) Yielda (%) TON
TOF
1
2
3
4
5
6
7
8
3
6
6
6
6
8
8
8
140
140
140
140
140
140
140
150
100
092
093
>99
093
098
098
>99
100
194
186
66.6
30.6
31.0
>198 >33.0
186
192
196
198
31.0
24.6
24.6
24.8
Catalysis by Complex 2b
The Pd-catalyzed reaction of 3a with 4b was also
tested using Pd complex 2b as catalyst with the results sum-
marized in Table 8, whose data indicated a good recyclabil-
ity, albeit under slightly more forced conditions than catal-
ysis by Pd complex 2a (Table 5), suggesting that the steric
hinderedness and the electron-withdrawing effect due to
Note: Reaction conditions: DMF (3 mL); FC77 (3 mL); 3a (0.5
mmol, 102.0 mg), 4b (0.75 mmol, 64.5 mg), NEt3 (1.5 mmol,
151.8 mg), 0.5 mol % Pd complex 2a (3.64 mg). After each
cycle, the DMF and FC77 layers were separated at 0 °C using a
separatory funnel. The FC77 layer was washed with 2 mL DMF
(or CH2Cl2) before proceeding to the next cycle.
a Based on GC yield (internal standard is NMP).

Mizoroki-Heck Reactions under Fluorous Biphasic Catalysis
J. Chin. Chem. Soc., Vol. 55, No. 1, 2008 93
Table 7. FBC recycling results of complex 2a as catalyst in MH
arylation of 4b and 3c
Table 9. FBC recycling results of complex 2b as catalyst in MH
arylation of 4b and 3b
Cycle No. Temp (°C) Time (hr) Yielda (%) TON
TOF
Cycle No. Time (h) Temp (°C) Yield (%) TON
TOF
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
087.2
082.3
083.8
092.0
094.0
093.6
086.0
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
1
2
3
4
5
6
7
8
3
3
3
6
6
6
6
6
140
140
140
140
140
140
140
140
100
100
100
100
100
100
100
100
200
200
200
200
200
200
200
200
66.7
66.7
66.7
33.4
33.4
33.4
33.4
33.4
Note: Reaction conditions: DMF (3 mL); FC77 (3 mL); 3c (0.5
mmol, 117 mg), 4b (1.0 mmol, 81.3 mg), NEt3 (1.5 mmol, 152.0
mg), 0.5 mol % Pd complex 2a (3.64 mg). After each cycle, the
DMF and FC77 layers were separated at 0 °C using a separatory
funnel. The FC77 layer was washed with 2 mL DMF (or CH2Cl2)
before proceeding to the next cycle.
Note: Reaction conditions: DMF (3 mL); FC77 (3 mL); 3b (0.5
mmol, 124.5 mg), 4b (1.0 mmol, 81.3 mg), NEt3 (1.5 mmol, 152
mg), 0.5 mol % Pd complex 2b (3.9 mg). After each cycle, the
DMF and FC77 layers were separated at 0 °C using a separatory
funnel. The FC77 layer was washed with 2 mL DMF (or CH2Cl2)
before proceeding to the next cycle.
a Based on GC yield (internal standard is NMP).
dicated by the fast TGAscans (Fig. 1), with thermal decom-
position temperatures >300 °C. The literature reported Pd
catalyst precursors, if thermally disintegrating at <120 °C,
would give catalytic pathways of MH arylation via nano-
particle, colloidal and/or molecular catalysis.19,28 The good
thermal stability of Pd complexes 2a-b might have contrib-
uted to the good recyclability in MH arylations since ther-
mal disintegrations would become less important.
Table 8. FBC recycling results of complex 2b as catalyst in MH
arylation of 4b and 3a
Cycle No. Time (h) Temp (°C) Yield (%) TON
TOF
1
2
3
4
5
6
7
8
3
3
3
6
6
6
6
6
140
140
140
140
140
140
140
140
100
100
100
100
100
100
100
100
200
200
200
200
200
200
200
200
66.7
66.7
66.7
33.4
33.4
33.4
33.4
33.4
X-ray Structure of Pd complex 2c
The X-ray structure of [PdCl2(4,4¢-bis-(CF3CF2CF2-
CH2OCH2)-2,2¢-bpy)] (2c), an analog of the Pd-complexes
in series, is shown in Fig. 2, with selected bond lengths and
angles. The coordination sphere around the Pd metal center
is square planar and the structural parameters around the Pd
metal center are in the normal range. The fluorinated pony-
Note: General procedures used being the same as those for Table
5 in recycling the catalyst. The amounts used: 3a (0.5 mmol,
102.0 mg), 4b (1.0 mmol, 81.3 mg), NEt3 (1.5 mmol, 152.0 mg),
0.5 mol % Pd complex 2b (3.9 mg).
longer fluorinated ponytails in 2b are seemingly greater.
The strong electron-withdrawing NO2 group at the
para position of aryl iodide greatly increases the MH
arylation catalyzed by Pd complex 2b, as shown in Table 9.
The first 3 cycles were completed at 140 °C in 3 h each and
the later cycles up to the 8th at 140 °C in 6 h each. Thus, the
MH arylations catalyzed by either 2a or 2b were equally
facile when an activated aryl halide, e.g., 3b was used as
the substrate.
Thermal Gravity Analysis of Pd Complexes 2a-b
The Pd complexes 2a-b, in addition to their great sol-
ubility in fluorinated solvents and the insolubility in com-
mon organic solvents, show a good thermal stability as in-
Fig. 1. The weight loss curves of Pd complexes 2a
(21F-Pd) and 2b (23F-Pd).

94 J. Chin. Chem. Soc., Vol. 55, No. 1, 2008
Lu et al.
with a series 5973 mass selective detector. The GC moni-
toring employed a HP 6890 GC using a 30 m ´ 0.250 mm
HP-1 capillary column with a 0.25 mm stationary phase
film thickness. Infrared spectra were obtained on a Perkin
Elmer RX I FT-IR Spectrometer. NMR spectra were re-
corded on Bruker AM 500 and Joel AM 200 using 5 mm
sample tubes. The residual peaks of d-DMF were used as
the reference peaks for both 1H and 13C NMR spectra; that
of FreonÒ 11 (CFCl3) for 19F-NMR spectra. Thermogravi-
metric analyses (TGA) were obtained on a TA Instruments
TGA51.
Fig. 2. Molecular plot of 2c. Selected bond lengths [Å]
and angles [°]: Pd-N(1) 2.039(6), Pd-N(2)
2.036(5), Pd-Cl(1) 2.2841(19), Pd-Cl(2) 2.288(2);
N(1)-Pd-N(2) 80.3(2), N(1)-Pd-Cl(1) 94.86(15),
N(1)-Pd-Cl(2) 173.79(14), N(2)-Pd-Cl(1)
174.36(14), N(2)-Pd-Cl(2) 94.11(16), Cl(1)-
Pd-Cl(2) 90.84(8).
Analytical data of 2a
(NMR data collected in d-DMF at 90 °C because of
solubility): yield 96%; 1H NMR (500 MHz, d-DMF) d 9.29
(d, 3JHH = 5.8 Hz, 2H, H6), 8.47 (s, 2H, H3), 7.81 (d, 3JHH
=
5.8 Hz, 2H, H5), 5.08 (s, 4H, bpy-CH2), 4.47 (t, 3JHF = 14.6
Hz, 4H, C10F21-CH2); 19F NMR (470.5 MHz, d-DMF) d
-80.9 (t, 3JFF = 7.52, 6F, -CF3), -121.0 (4F), -121.3 (20F),
-122.1 (4F), -122.7 (4F), -125.5 (4F); 13C NMR (113 MHz,
d-DMF) d 74.2 (bpy-CH2), 68.2 (CH2CF2), 120.3, 124.5,
140.9, 151.8, 157.3 (bpy), 105.0~116.0 (C10F21); FT-IR
(cm-1): 1622.9, 1558.3 (nbpy, m), 1208.3, 1150.5 (nCF2, vs);
HR-MS (FAB): (M+; m/z=) C34N2H14F42O2Pd35Cl2 calcd
1455.8869, found 1455.8842; C34N2H14F42O2Pd35Cl37Cl
calcd 1457.8767, found 1457.8741; C34N2H14F42O2Pd37Cl2
calcd 1459.8737, found 1459.8734.
tails point away from the metal center. Hence it has been as-
sumed that the steric hindrance of long, fluorinated pony-
tails on the Pd center is minimal during the catalytic reac-
tions employing Pd complex 2a-b as catalyst. With regard
to the planar [PdCl2(2,2¢-bpy)] skeleton, the two fluori-
nated ponytails are also seen to be positioned towards the
opposite sides. In the crystalline state of 2c, one of the fluo-
rinated ponytails exhibits the trans conformation (chain
terminal C13-C14-C15-C16), whereas the other exhibits
the gauche conformation (chain terminal C17-C18-C19-
C20).
Analytical data of 2b
(NMR data collected in d-DMF at 90 °C because of
solubility): yield 90.4%; 1H NMR (500 MHz, d-DMF) d
9.29 (d, 3JHH = 5.8 Hz, 2H, H6), 8.47 (s, 2H, H3), 7.81 (d,
3JHH = 6.0 Hz, 2H, H5), 5.09 (4H, s, bpy-CH2), 4.48 (t, 3JHF
= 14.29 Hz, 4H, C10F23-CH2); 19F NMR (470.5 MHz, d-
DMF) d -81.0 (t, 3JFF = 7.52, 6F, -CF3), -119.3 (4F), -121.3
(24F), -122.2 (4F), -122.9 (4F), -125.7 (4F); 13C NMR (113
MHz, d-DMF): due to the extremely weak signal the 13C
NMR spectrum was not obtained even at 90 °C; FT-IR
(cm-1): 1601.8, 1557.6 (nbpy, m), 1207.4, 1152.1 (nCF2, vs);
HR-MS (FAB): (M+; m/z=) C36N2H14F46O2Pd35Cl2 calcd
1555.8732, found 1555.8721; C36N2H14F46O2Pd37Cl35Cl
calcd 1557.8679, found 1557.8656; C36N2H14F46O2Pd37Cl2
calcd 1559.8674, found 1559.8662.
CONCLUSIONS
The recovery and recycling of catalyst in Pd-cata-
lyzed Mizoroki-Heck arylations employing the FBC strat-
egy were demonstrated. The prepared Pd complexes 2a-b
were with very high fluorine contents and worked well in
the Mizoroki-Heck reaction of a,b-unsaturated carboxylic
acid/ester and aryl iodide for up to 8 cycles. There was also
the excellent selectivity of trans products. The thermal sta-
bility of Pd complexes 2a-b were also noted to decompose
at >300 °C.
EXPERIMENTAL SECTION
General
Analytical data of 2c
Yield 98%; 1H NMR (500 MHz, d-Me2SO) 9.08 (2H,
Gas chromatographic/mass spectrometric data were
obtained using an Agilent 6890 Series gas chromatograph
d, 3JHH = 5.9 Hz, H6), 8.37 (2H, s, H3), 7.74 (2H, d, 3JHH
=

Mizoroki-Heck Reactions under Fluorous Biphasic Catalysis
J. Chin. Chem. Soc., Vol. 55, No. 1, 2008 95
5.9 Hz, H5), 4.96 (4H, s, bpy-CH2), 4.42 (4H, t, 3JHF = 14.6
(1.50 mmol, 152.0 mg), and the Pd complex 2b (1 mol %)
or the recovered Pd-catalyst after each run. Then the reac-
tion mixture was set to reflux in DMF/FC77 (2 mL each) at
120-140 °C for 3-6 h before the reaction was stopped and
the two layers separated at 0 °C using a separating funnel.
The FC77 fraction was retained for recycling experiments.
Hz, CF2CH2); 19F NMR (470.5 MHz, d-Me2SO) -119.8 (2F,
CH2CF2), -127.1 (2F, s, CH2CF2CF2), -80.4 (3F, t, 3JHF
=
9.2 Hz, CF3); 13C NMR (113 MHz, d-Me2SO) 71 (bpy-
CH2), 65.5 (CH2CF2), 121.0, 124.7, 149.6, 152.1, 156.1
(bpy), 115~119 (CF2CF2CF3); FT-IR (cm-1): 1623.4, 1559.5
(nbpy, m), 1232.4, 1196.6 (nCF2, vs); HR-MS (FAB):
(M-Cl)+ C20N2H14F14O2Pd35Cl calcd m/z 720.9555, found
m/z 720.9564; C20N2H14F16O2Pd37Cl calcd m/z 722.9559,
found m/z 722.9551.
Complex 2b catalyzed MH reaction with 3a as the
substrate
Under FBC, the vessel was charged with DMF (3
mL), FC77 (3 mL), 3a (0.50 mmol, 102.0 mg), 4a (1 mmol,
71.0 mg), NEt3 (1.5 mmol, 152 mg), and the 1 mol % Pd
complex 2b or the recovered Pd-catalyst after each run.
The reaction mixture was refluxed at 120-140 °C for 6 h be-
fore the reaction was stopped and the two layers separated
at 0 °C using a separatory funnel. The FC77 fraction was
retained for recycling experiments.
Pd Complexes 2a-b Catalyzed MH Arylation of
H2C=CHCO2H under FBC
Under FBC, the vessel was charged with DMF (3
mL), FC77 (3 mL), C6H5I or its derivative (0.50 mmol),
H2C=CHCO2H (1 mmol, 71 mg), NEt3 (1.50 mmol, 151.8
mg), and the Pd-catalyst 2a-b (1 mol %). Then the reaction
mixture was set to reflux around 140 °C for 6 h before the
reaction was stopped and the two layers separated at 0 °C
using a separating funnel. The FC77 fraction was retained
for recycling experiments.
Pd Complexes 2a-b Catalyzed MH Arylation of
H2C=CHCO2Me under FBC
Under FBC, the vessel was charged with DMF (3
mL), FC77 (3 mL), C6H5I (3a) or its derivative (0.50
mmol), H2C=CHCO2Me (4b) (0.75 mmol, 64.5 mg), NEt3
(1.50 mmol, 151.8 mg), and the Pd-catalyst 2a-b (0.5 mol
%). Then the reaction mixture was set to reflux around 140
°C for several hours before the reaction was stopped and
the two layers separated at 0 °C using a separating funnel.
The FC77 fraction was retained for recycling experiments.
Complex 2a catalyzed MH reaction with 3b as the
substrate
In a typical run, the reaction vessel was charged with
3b (0.50 mmol, 124.5 mg), 4a (1 mmol, 71.0 mg), NEt3
(1.50 mmol, 152.0 mg), and the Pd complex 2a (1 mol %)
or the recovered Pd-catalyst after each run. Then the reac-
tion mixture was set to reflux in DMF/FC77 (2 mL each) at
120-140 °C for 3-6 h before the reaction was stopped and
the 2 layers separated using a separating funnel at 0 °C. The
FC 77 fraction was retained for recycling experiments.
MH reaction with 3a as the substrate
Under FBC, the vessel was charged with DMF (3
mL), FC77 (3 mL), 3a (0.50 mmol, 102.0 mg), 4b (0.75
mmol, 64.5 mg), NEt3 (1.50 mmol, 151.8 mg), and the 0.5
mol % Pd complex 2a-b. The reaction mixture was re-
fluxed at 140 °C for 6 h before the reaction was stopped and
the two layers separated at 0 °C using a separatory funnel.
The FC77 fraction was retained for recycling experiments.
Complex 2a catalyzed MH reaction with 3a as the
substrate
In a typical run, the reaction vessel was charged with
3a (0.50 mmol, 102 mg), 4a (1 mmol, 71.0 mg), NEt3 (1.50
mmol, 152.0 mg), and the Pd complex 2a (1 mol %) or the
recovered Pd-catalyst after each run. Then the reaction
mixture was set to reflux in DMF/FC77 (2 mL each) at
120-140 °C for 3-6 h before the reaction was stopped and
the two layers separated at 0 °C using a separating funnel.
The FC77 fraction was retained for recycling experiments.
MH reaction with 3b as the substrate
In a typical run, the reaction vessel was charged with
3b (0.50 mmol, 123.5 mg), 4b (0.75 mmol, 64.5 mg), NEt3
(1.50 mmol, 151.8 mg), and the Pd complex 2a-b (0.5 mol
%) or the recovered Pd-catalyst after each run. Then the re-
action 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 at 0 °C using a separating funnel. The
FC77 fraction was retained for recycling experiments.
Complex 2b catalyzed MH reaction with 3b as the
substrate
In a typical run, the reaction vessel was charged with
3b (0.50 mmol, 124.5 mg), 4a (1 mmol, 71.0 mg), NEt3

96 J. Chin. Chem. Soc., Vol. 55, No. 1, 2008
Lu et al.
4. Horvath, I. T.; Kiss, G.; Cook, R. A.; Bond, J. E.; Stevens, P.
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MH reaction with 3c as the substrate
In a typical run, the reaction vessel was charged with
3c (0.50 mmol, 117.0 mg), 4b (0.75 mmol, 64.5 mg), NEt3
(1.50 mmol, 151.8 mg), and the Pd complex 2a (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 to 8 h before the reac-
tion was stopped and the two layers separated at 0 °C using
a separating funnel. The FC77 fraction was then used for
recycling experiments.
5. Klement, I.; Lütjens, H.; Knochel, P. Angew. Chem., Int. Ed.
Engl. 1997, 36, 1454.
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X-ray crystal data of 2c
9. Betzemeier, B.; Cavazzini, M.; Quici, S.; Knochel, P.
Tetrahed. Lett. 2000, 41, 4343.
C20H14Cl2F14N2O2Pd, FW = 757.63, T = 295(2) K,
Mo Ka 0.71073 Å, Triclinic space group P-1, a = 6.8812(2)
Å, b = 11.5712(4) Å, c = 16.8760(6) Å, a = 80.4160(17)°, b
= 85.0630(18)°, g = 88.5460(18)°, V = 1319.98(8) Å3, Z =
2, Dc = 1.906 Mg/m3, m = 1.027 mm-1, F(000) = 740, Crys-
tal size 0.50 ´ 0.15 ´ 0.10 mm3, 1.78 < q < 27.49°, - 8 £ h £
8, -14 £ k £ 14, -21 £ l £ 21, No reflns. = 5833 [R(int) =
0.0882], Completeness 96.4%, Max. and min. trans. 0.911-
0.600, Full-matrix least-squares on F2, No param. = 371,
GoF = 1.105, R = 0.0780, Rw = 0.2092 [I>2s(I)], Extin.
Coef. = 0.218(16).
10. Vincent, J. M.; Rabion, A.; Yachandra,V. K.; Fish, R. H.
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ACKNOWLEDGMENTS
16. Beletskaya, I. P.; Cheprakov, A. V. Chem. Rev. 2000, 100,
3009.
The authors thank the National Science Council (NSC
95-2113-M-027-002), Taipei, Taiwan, for financial sup-
port.
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Supporting Information
Crystal data CCDC-645169, which can be obtained
free of charge from the Cambridge Crystallographic Data
Center via www.ccdc.cam.ac.uk/data_request/cif.
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