Impregnated palladium on magnetite as catalyst for direct arylation of heterocycles

Article abstract of DOI:10.1016/j.tet.2015.12.039

Palladium impregnated on magnetite is an efficient, cheap and easy to prepare catalyst for the direct arylation of heterocycles. Good yields are afforded under relatively mild conditions and a broad substrate scope is evident. The catalyst is regioselective in many cases, affording arylated products, at the C2- or C3-position (depending of the heterocycle used). The methodology can be extended to prepare chromenes through an intramolecular direct arylation reaction. Some evidence is provided for two catalyst deactivation pathways, which prevents efficient recycling.

Full text of DOI:10.1016/j.tet.2015.12.039

Accepted Manuscript
Impregnated palladium on magnetite as catalyst for direct arylation of heterocycles
Rafael Cano, Juana M. Pérez, Diego J. Ramón, Gerard P. McGlacken
PII:
S0040-4020(15)30287-8
10.1016/j.tet.2015.12.039
TET 27365
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 14 October 2015
Accepted Date: 18 December 2015
Please cite this article as: Cano R, Pérez JM, Ramón DJ, McGlacken GP, Impregnated palladium
on magnetite as catalyst for direct arylation of heterocycles, Tetrahedron (2016), doi: 10.1016/
j.tet.2015.12.039.
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Impregnated palladium on magnetite as
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Rafael Cano, Juana M. Pérez, Diego J. Ramón and Gerard P. McGlacken

1
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Tetrahedron
journal homepage: www.elsevier.com
Impregnated palladium on magnetite as catalyst for direct arylation of heterocycles
Rafael Canoa, Juana M. Pérezb Diego J. Ramónb and Gerard P. McGlackena
,
aDepartment of Chemistry and Analytical & Biological Chemistry Research Facility (ABCRF), University College Cork, Ireland
bInstituto de Síntesis Orgánica (ISO) and Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Alicante, Apdo. 99, E-03080 Alicante,
Spain
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
Palladium impregnated on magnetite is an efficient, cheap and easy to prepare catalyst for the
direct arylation of heterocycles. Good yields are afforded under relatively mild conditions and a
broad substrate scope is evident. The catalyst is regioselective in many cases, affording arylated
products, at the C2- or C3-position (depending of the heterocycle used). The methodology can
be extended to prepare chromenes through an intramolecular direct arylation reaction. Some
evidence is provided for two catalyst deactivation pathways, which prevents efficient recycling.
Available online
Keywords:
2009 Elsevier Ltd. All rights reserved
.
Direct arylation
Heterogeneous catalysis
Heterocycles
Magnetite
Palladium
———
Corresponding author. Tel.: +353 21 4902866; fax: +353 21 4274097; e-mail: g.mcglacken@ucc.ie

2
Tetrahedron
ACCEPTED MANUSCRIPT
1. Introduction
iodonium salt was modified (entry 6). The yield of 3a was
increased to 62% with the addition of 3 equivalents of the salt.
The temperature effect was evaluated at this point. Increasing the
temperature to 100 ºC only gave a slightly higher yield (entry 7).
However the best yield was obtained at 60 ºC (entry 8).
Unfortunately, it was not possible to reduce the temperature
without a significant reduction in yield (entries 9 and 10). The
impact of the solvent was evaluated (entries 11–13). The reaction
failed in dioxane, water and toluene. Finally, with the best
conditions in hand a reaction was performed in the absence of
catalyst (entry 14). Only starting material was recovered,
confirming the catalytic role of the palladium on magnetite.
The formation of aryl-aryl (Ar-Ar') bonds and heteroaryl (Ar-
Het and Het-Het') analogues is an important transformation in
organic synthesis due to number of compounds containing these
moieties in the pharmaceutical and other industries.1 Traditional
methods2 for the introduction of the Ar-Ar' bond (e.g. Suzuki-
Miyaura, Stille, Negishi and other named reactions) suffer from
drawbacks as they require the installation of activating groups on
both coupling partners. The associated waste (B, Sn, Zn-based) is
also a major problem for the pharmaceutical and other industries.
A modern, efficient and environmentally friendly alternative is
termed Direct Arylation (DA).3 Through catalytic C–H
activation,4 DA avoids the preactivation steps, establishing a
convenient pathway to arylated compounds in terms of atom
economy and environmental impact.5
Table 1
Optimization of the reaction conditionsa
In the last decade a broad number of catalytic systems have
been used for the DA of heterocycles.6 However, most of these
methodologies are based on homogeneous catalysis and harsh
reaction conditions. Homogeneous catalysis suffers from a
number of drawbacks. Deactivation because of metal aggregation
and precipitation7 and separation of the catalyst from the API
product8 seriously impede scale-up of many potentially useful
transformations. Heterogeneous catalysis9 on the other hand,
offers a more attractive approach. Heterogeneous catalysts
possesses good thermal stability and can usually be removed
from the reaction media and can, in principle, be recycled.
Entry 2a (mol%)
Solvent
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
Dioxane
H2O
T (º C) Pd (mol%) Yield (%)b
1
2
80
80
80
80
80
80
100
60
40
25
60
60
60
60
6
22
45
31
11
59
62
65
71
39
0
110
220
300
220
220
300
300
300
300
300
300
300
300
300
6
3
6
4
3
5
10
10
10
10
10
10
10
10
10
0
Recently notable progress has been made in the search for
heterogeneous systems for DA.10 Palladium has been the most
employed transition-metal to accomplish this transformation.
Examples include Pd supported on zeolite,11 modified silica,12
metal organic frameworks,13 carbon14 and mesocellular foam.15
Pd has been incorporated within a bimetallic heterodimer with
magnetite using thermal decomposition.16 Discerning whether the
catalyst behaves in a homogeneous or heterogeneous manner is
difficult and complex.10 In many cases, heterogeneous catalyst
precursors are used, but leaching to homogeneous species17 (e.g.
soluble nanoparticles) is likely, although both Glorius14b and
Bäckvall15 have provided good evidence for a heterogeneous
pathway in Pd-catalysed DA reactions in their systems. However
in both cases recycling of the catalyst was not possible (Pd/C and
PD/mesocellular foam respectively). Other heterogeneous
systems used are based on copper,18 nickel19 and TiO2.20 Even a
transition-metal-free arylation methodology has been reported
with similar overall objectives.21
6
7
8
9
10
11
12
13
14c
0
0
PhMe
EtOH
0
0
a Reaction carried out using compound 1a (0.5 mmol), 2a (0.6 mmol), in
b
1.5 mL of solvent, unless otherwise stated. Isolated yield after column
chromatography. c Reaction performed in absence of catalyst.
Once the best reaction conditions were found for this process,
a number of impregnated metal catalysts were tested (see SI).
Only the palladium on magnetite showed high activity. However,
the bimetallic palladium-copper catalyst did give a small amount
of arylated product. Finally the reaction was also performed
using Pd-free magnetite nanoparticles (see SI) to confirm the role
of Pd. No product was observed.
As part of our ongoing project on the use of magnetite22 and
impregnated-metal magnetite23 as catalysts for organic synthesis,
we report here a simple, versatile and easy to recover catalyst for
the direct arylation of heterocycles and other aryls under
relatively mild reaction conditions.
The optimised protocol was then applied to other prominent
heterocycles. When benzofuran was used as substrate, the
arylated product was isolated in an excellent yield of 99% (entry
1). The reaction was completely regioselective for the C2
position. Indoles containing electron withdrawing substituents
coupled well (entries 2-4), affording the arylated products in
yields from 58-83% and no issues were apparent with these
compounds bearing free NH groups. For all the indoles tried, the
arylation took place at the C-2 position selectively.
2. Results and discussion
2.1. Direct arylation of heterocycles
The supported catalyst was prepared as previously
published.23c We chose the arylation of benzothiophene (1a)
using diphenyliodonium tetrafluoroborate (2a) as a model
reaction (Table 1). Our first attempt gave the corresponding
arylated heterocycle (3a) after 24h. Arylation occurred
selectively at C3 but in a low yield (entry 1). Increasing the
equivalents of 2a achieved a small increase in yield (entries 2 and
3). A reduction of palladium loading (3 mol%) gave a lower
conversion (entry 4) and an increase (10 mol%) improved the
yield (entry 5). With the optimised catalyst loading in hand, the

3
Table 2
Table 4
ACCEPTED MANUSCRIPT
Substrate scope: arylation of different heterocyclesa
Substrate scope: arylation of tiophenesa
Ph
PdO-Fe3O4 (10 mol%)
+
Ph2IBF4
R
R
X
S
EtOH, 60 ºC
24 h
4
2a
5
Entry
X
R
Product
3b
Yield (%)b
Entry
R
Product
5a
Yield (%)
1
2
3
4
O
H
99
83
79
58
1
2
3
4
H
39
18
51
48
NH
NH
NH
7-CO2Me
5-F
3c
2-Br
3-Br
5b
3d
5c
4-Br
3e
a Reaction carried out using the corresponding heterocycle 1 (0.5 mmol), 2a
5d
b
(1.5 mmol), in 1.5 mL of EtOH.
chromatography.
Isolated yield after column
a Reaction carried out using the corresponding heterocycle 4 (0.5 mmol), 2a
b
(1.5 mmol), in 1.5 mL of EtOH.
chromatography.
Isolated yield after column
The use of other iodonium salts was also studied (Table 3).
Chemoselective arylation could be performed by introducing one
Once the substrate scope was evaluated, the recyclability of
the catalyst was tested. After a standard reaction using
benzofuran as heterocycle, the catalyst was retained in the
reaction vessel using a magnet and washed several times with
ethanol. The vessel was then charged with a new set of reagents
and the standard conditions applied. The corresponding product
3b was obtained in 49% yield after the second cycle and 18%
after the third. These results show deactivation of the catalyst.
While others have shown that heterogeneous catalysis and
recyclability can prove mutually exclusive, no examination of the
reasons for deactivation have been proposed in these systems.
non-transferable aryl group such as 2,3,5-triisopropylphenyl
15
(TRIP).14b,
Using this approach, an arylated benzothiophene
was isolated in low yield (entry 1, 38%). Better yields (66 and
71%) were obtained using benzofuran and methyl phenyl groups
(entries 2 and 3). An electron poor aryl group was also shown to
work reasonably well (55% yield, entry 4). Finally an electron
rich aryl group was transferred in 84% yield, this time using a
symmetrical iodonium salt (entry 5). The catalyst facilitated
excellent regioselectivity in all the cases (arylation of benzofuran
at C2-position and thiophene at C3).
Table 3
We thus sought to examine the catalyst structure before and
after the reaction. Transmission electron microscopy (TEM)
analysis showed that pre- and post-reaction particles displayed a
similar appearance. Also no sinterization of the particles could be
observed post-reaction. Additionally both pre- and post-reaction
particles showed an identical particle-size distribution. X-ray
photoelectron spectroscopy (XPS) analysis of the catalyst did not
show any change in oxidation state of the palladium on the
magnetite surface. The XPS spectra of the post-reaction sample
showed, after deconvolution, two peaks at 337.0 and 342.1 eV,
which correspond to the binding energies of PdO 3d5/2 and PdO
3d3/2 respectively. The spectra is identical to that taken of the
catalyst pre-reaction (See SI). Thus we cannot attribute
deactivation of the catalyst to an oxidation change at the
surface.24
Substrate scope: use of different diaryliodonium saltsa
Entry
X
S
Ar1
Ar2
Ar2 position Product Yield (%)b
1
2
3
4
TRIP
TRIP
TRIP
TRIP
4-MeC6H4
4-MeC6H4
2-MeC6H4
4-ClC6H4
C3
C2
C2
C2
C2
3f
3g
3h
3i
38
71
66
55
84
O
O
O
O
5
4-MeOC6H4 4-MeOC6H4
3j
a
Reaction carried out using the corresponding heterocycle 1 (0.5 mmol), 2
We then hypothesised that leaching of the Pd from the support
might be occurring, rendering the insoluble catalyst framework
inactive, when reused. The phenomenon of leaching was studied
by inductively coupled plasma mass spectrometry (ICP-MS).
Here, the reaction mixture was filtered hot after the reaction and
the homogeneous solution was tested by dissolved Pd. Only
1.96% of the initial amount of palladium was detected. This
amount seems insufficient to explain the deactivation given the
lower turnover numbers observed when lower Pd loading was
used (Table 1). The inability of the solution phase to catalyse the
arylation of benzofuan was confirmed by observation of the
reaction progress after filtration. Thus after two hours, the
catalyst was filtered hot. No reaction progress was observed after
this point confirming that no active species were solubilised
under the reaction conditions. The above tests point strongly to
heterogeneous catalysis, in line with the conclusion made by
Glorius is his arylation of 2-butylthiophene.14b
b
(1.5 mmol), in 1.5 mL of EtOH.
chromatography.
Isolated yield after column
The protocol was then extended to the arylation of simple
thiophenes under the same conditions (Table 4). Using
thiophenes, the process was not as high yielding or selective as
with previous substrates and a mixture of the mono- and
diarylated heterocycles was obtained in 39% overall yield (entry
1). With 2-bromothiophene, only 18% of the mono-arylated
heteocycle was recovered (entry 2). Better yield was obtained
with the 3-bromothiophene (entry 3). In both cases the bromine
remained intact, allowing for further functionalisation. Finally,
2,2'-bithiophene gave the corresponding monoarylated product
selectively in 48% yield (entry 4).
Clearly, if leaching is ruled out, some change at the surface
must occur which deactivates the catalyst.25 X-ray fluorescence

4
Tetrahedron
(XRF) was then used to gain further insight at the catalyst
test, the reaction was performed in the absence of catalyst under
ACCEPTED MANUSCRIPT
surface. More specifically, 5.4%
o
f iodine was detected at the
the optimised conditions (entry 18). Only starting material was
recovered confirming the role of palladium in this process.
catalyst surface. The adsorbance of halides on the surface of Pd
catalysts has previously been shown to affect the activity of
heterogeneous catalysts and we believe this to be this case here
also.26
The best reaction conditions were then applied to different
substrates to evaluate the reaction scope (Table 6). First we
studied the tolerance of substituents on the phenoxy group. The
presence of a methoxy group was tolerated with only a small
detriment in yield (entry 2). Good yield was obtained with a
methyl group at the 4-position of the ring (entry 3). The
introduction of electron-withdrawing groups had a beneficial
effect on the process, and excellent yields were achieved (93 and
92%, entries 4 and 5). Then the effect of substitution on the
phenoxy group was evaluated. Similarly good results were
obtained using electron-withdrawing groups (87-92%, entries 5-
7), although a mixture of regioisomers was obtained when a
meta-F substituent was present. Little impact on the yields was
observed on substitution of the halo-aryl either, and very good
yields were observed (84 and 77%, entries 8 and 9).
2.2. Intramolecular direct arylation
Encouraged by the success that we obtained in the direct
arylation of heterocycles, we decided to apply palladium on
magnetite to an intramolecular arylation.6d,27
A different
mechanism is operative here and thus application to this reaction
would give a good indication of the broad utility of the catalyst.
We chose the intramolecular arylation of haloether 6a to obtain
the corresponding chromene 7a (Table 5) as a suitable reaction.
Table 5
Optimization of the reaction conditions for intramolecular direct arylationa
Table 6
Substrate scope for intramolecular direct arylationa
Entry Base (mol%)
Solvent
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
PhMe
DMF
T (º C) Pd (mol%) Yield (%)b
1
2
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
160
120
140
0.1
1
5
9
KOAc (200)
KOAc (200)
KOAc (200)
KOAc (200)
KOAc (200)
KOAc (200)
KOAc (100)
KOAc (300)
KOH (200)
Entry
R1
H
H
H
H
H
H
H
H
F
R2
H
R3
H
Product
7a
Yield (%)b
3
2
20
61
85
77
64
71
5
1
2
3
4
5
6
7
8
9
85
75
86
93
92
89c
87
84
77
4
5
H
4-MeO
4-Me
4-Cl
4-F
3-F
2-F
H
7b
5
10
15
10
10
10
10
10
10
10
10
10
10
10
0
H
7c
6
H
7d
7
H
7e
8
H
7f
9
H
7g
10
11
12
13
14
15
16
17
18c
0
NaOH (200)
NaOAc (200)
K2CO3 (200)
KOAc (200)
KOAc (200)
KOAc (200)
KOAc (200)
KOAc (200)
KOAc (200)
CF3
H
7h
56
0
H
7i
a Reaction carried out using compound 6 (0.5 mmol), KOAc (1 mmol), in 2
0
b
mL of DMA. Isolated yield after column chromatography. c A mixture of
74
25
75
63
0
isomers was obtained: 1-Fluoro-6H-benzo[c]chromene (7f) and 3-Fluoro-6H-
benzo[c]chromene (7f’) (45:55).
tBuOH
DMA
DMA
DMA
The recyclability of the catalyst was also investigated in this
case also. In a similar way to the intermolecular reaction, the
catalyst was removed using a magnet and reused using the
standard conditions (as in Table 5, entry 5). Again deactivation of
the catalyst was observed. This time no product was detected
after the second cycle of reaction. ICP-MS analysis of the
reaction solution showed 3.3% of the Pd has leached. Post-
reaction TEM analysis revealed substantial sintering of palladium
nanoparticles had occurred (See SI for particle distribution). XPS
analysis also showed a distinctive change and four peaks were
observed. Two peaks at 336.9 and 342.2 eV, correspond to the
binding energies of PdO 3d5/2 and PdO 3d3/2 respectively. The
two other peaks at 334.9 and 340.1 eV, correspond to the binding
energies of Pd 3d5/2 and Pd 3d3/2 respectively. The ratio between
the two oxidation states was Pd:PdO 2:1. Clearly some reduction
of the PdO species had occurred perhaps forming inactive Pd-
black aggregates. The hot filtration test determined that no
reaction progress occurred after filtration. Thus, we believe that
changes in the oxidation state of Pd during the reaction renders
a Reaction carried out using compound 6a (0.5 mmol), KOAc (1 mmol), in
b
2 mL of solvent, unless otherwise stated. Isolated yield after column
chromatography. c Reaction performed in absence of catalyst.
Firstly, the optimum catalyst loading was established (entry 1–
6). Again 10 mol% of Pd was needed to obtain the best chemical
yield of 85% (entry 5). Then the effect of the base was tested
(entries 7–12). When 1 equivalent of base was used the yield of
7a was reduced to 64% (entry 7). The addition of 3 equivalents
was not beneficial for the cyclisation process (entry 8). Different
bases were tried, but none were as efficient as KOAc (entries 9–
12). The impact of the solvent was studied (entries 13–15). Only
DMF gave a comparable yield (74%), but was slightly lower to
the one obtained with N,N-dimethylacetamide (DMA). Finally
the temperature was modified. Neither a higher, nor lower
temperature gave better yields (entries 16 and 17). As a control

5
the recovered Pd/magnetite unable to catalyse subsequent
reactions.
300ºC, Tcolu = 60ºC (3 min) and 60-270 ºC (15 ºC/min), P =
ACCEPTED MANUSCRmnIPT
40 kPa. Thin layer chromatography (TLC) was carried out on
Schleicher & Schuell F1400/LS 254 plates coated with a 0.2 mm
layer of silica gel; detection by UV254 light, staining with
phosphomolybdic acid [25 g phosphomolybdic acid, 10 g
Ce(SO4)2 4 H2O, 60 mL of concentrated H2SO4 and 940 mL
H2O]. Column chromatography was performed using silica gel 60
of 40-63 mesh. The ICP-MS analyses were carried out on a
Thermo Elemental VGPQ-ExCell spectrometer.
3. Conclusion
In conclusion, we have demonstrated that palladium
impregnated on magnetite is a cheap, selective and versatile
catalyst for the direct arylation of heterocycles under mild
conditions. The process can be applied to a number of substrate
and reaction types. In addition, the magnetic properties of the
catalyst allow its separation from the reaction media very easily.
Decreased yields are observed on reuse of the catalysts in the
intermolecular arylation of heterocycles using iodonium salts and
no reuse is possible in the intramolecular arylation reactions
tested using aryl halides. Preliminary studies suggest that halide
ligation to the Pd surface may inhibit subsequent reaction when
using iodonium salts. In intramolecular DA reactions using aryl
halides, substantial changes to the Pd particle distribution and
size are observed. A change in oxidation state of the Pd may also
be a cause of inhibition. These dramatic changes in the nature of
the catalyst are inevitable considering the conditions required
(140 ºC in DMA). Work is ongoing to utilise the insights
gathered here to allow for full and convenient recycling of
Pd/magnetite.
4.2. General procedure for the preparation of impregnated
palladium on magnetite catalyst.
To a stirred solution of PdCl2 (177 mg, 1 mmol), KCl (1 g, 13
mmol, to increase the palladium solubility) in deionized water
(120 mL) was added Fe3O4 (4 g, 17 mmol, powder <5 mm, BET
area: 9.86 m2/g). After 10 min at room temperature, the mixture
was slowly basified with NaOH (1 M) until pH around 13. The
mixture was stirred during 1 day at room temperature in air. After
that, the catalyst was filtered and washed with deionized water (3
x 10 mL). The solid was dried at 100 ºC during 24 h in a standard
glassware oven, obtaining the expected catalyst: incorporation of
palladium of 3.0% according to XRF; by XPS the palladium on
the surface was determined as 24.8%; the BET area surface was
13.6 m2/g.
4. Experimental section
4.3. General prodecure for the preparation of the diaryliodonium
tetrafluoroborates
4.1. General information
The diaryliodonium tetrafluoroborates were prepared
following the procedures described by Olofsson et al.28 and
Gaunt et al.29
Solvents and reagents were used as obtained from commercial
sources and without purification. H NMR (400 MHz) spectra
1
and 1H NMR (300 MHz) spectra were recorded on Bruker
Avance 400 and Bruker Avance 300 NMR spectrometers
respectively in proton coupled mode. 13C NMR (150 MHz)
spectra and 13C NMR (75.5 MHz) spectra were recorded on
Bruker Avance 400 and Bruker Avance 300 NMR spectrometers
respectively in proton decoupled mode at 20 °C in deuterated
chloroform using tetramethysilane as internal standard; chemical
shifts are given in δ (parts per million) and coupling constants (J)
in Hertz Low-resolution mass spectra were recorded on a Waters
Quattro Micro triple quadropole instrument in electrospray
ionisation (ESI) mode using 50% acetonitrile-water containing
0.1% formic acid as eluent; samples were made up in acetonitrile.
High resolution precise mass spectra (HRMS) were recorded on a
Waters LCT Premier Tof LC-MS instrument in electrospray
ionisation (ESI) mode using 50% acetonitrile-water containing
0.1% formic acid as eluent; samples were made up in acetonitrile.
Infrared spectra were measured as pressed potassium bromide
(KBr) for solids or thin films on sodium chloride plates for
liquids on a Perkin-Elmer FT-IR spectrometer. Melting points
were obtained with a Reichert Thermovar apparatus. XPS
analyses were carried out on a VG-Microtech Mutilab. XRD
analyses were obtained on a BRUKER D-8 ADVANCE
diffractometer with Göebel mirror, with a high temperature
4.3.1. Diphenyliodonium tetrafluoroborate (2a)28. m-CPBA (24
mmol, 5.120 g) was dissolved in CH2Cl2 (80 mL). To the solution
was added iodobenzene (21.6 mmol, 2.48 mL) followed by slow
addition of BF3·OEt2 (54.4 mmol, 6.8 mL) at room temperature.
The resulting yellow solution was stirred at room temperature for
30 min and then cooled to 0 ºC and PhB(OH)2 (24 mmol, 2.960
g) was added. After 15 min of stirring at room temperature, the
crude mixture was applied on a silica plug (20 g) and eluted with
CH2Cl2 (2 x 100 mL) followed by CH2Cl2/MeOH (2 x 100 mL).
The latter solution was concentrated and diethyl ether (40 mL)
was added to the residue to induce precipitation. The solution
was allowed to stir for 15 min, and then the solid was filtered and
washed several times with diethyl ether and then dried in vacuo.
White solid; yield 5.960 g (75 %); m.p. = 133-135ºC (Hexane);
1
IR (KBr): ν 1559, 1471, 1443, 1287, 1167, 1053, 740 cm-1; H-
NMR (300 MHz, DMSO) δ: 7.54 (4H, t, J = 7.6 Hz), 7.68 (2H, t,
J = 7.4 Hz), 8.25 (4H, d, J = 7.3 Hz). 13C-NMR (75 MHz,
DMSO) δ: 116.4 (2C), 131.7 (4C), 132.0 (2C), 135.1 (4C). 19F
NMR (282 MHz, DMSO): δ -148.2 (br. s), -148.3 (dd, J = 2.3,
1.2 Hz).
The appropriate iodoarene (5 mmol) was added to a stirred
solution of m-CPBA (7.5 mmol, 1.6 g) in acetic anhydride (10
ml) and the solution was stirred for 1 h at room temperature after
which 1,3,5-triisopropyl benzene (6.5 mmol, 1.32 mL) was added
and the solution cooled to 0 ºC. Tetrafluoroboric acid (50%
aqueous, 10 mmol, 1.25 mL) was added over 15 min via syringe
pump and the solution stirred at 0 ºC for 30 min before being
allowed to warm to rt. After 6 h the solution was recooled to 0 ºC
and water (100 mL) was slowly added with fast stirring. The
solution was extracted with CH2Cl2 (2 x 50 ml) and the combined
organic extracts dried (MgSO4) and evaporated. The pure
iodonium tetrafluoroborate salts were precipitated with Et2O
from a concentrated solution of hot CH2Cl2 and obtained by
chamber (up to 900ºC), with
a
X-ray generator
KRISTALLOFLEX K 760-80F (3KW, 20-60KV and 5-80mA).
TEM images were obtained on a JEOL, model JEM-2010
equipped with an X-ray detector OXFORD INCA Energy TEM
100 for microanalysis (EDS). XRF analyses were obtained on a
PHILIPS MAGIX PRO (PW2400) X-ray spectrometer equipped
with a rhodium X-ray tube and a beryllium window. BET
isotherms were carried out on a AUTOSORB-6 (Quantachrome),
using N2. The chromatographic analyses (GLC) were determined
with a Hewlett Packard HP-5890 instrument equipped with a
flame ionization detector and 12 m HP-1 capillary column (0.2
mm diam, 0.33 mm film thickness, OV-1 stationary phase), using
nitrogen (2 mL/min) as a carrier gas, Tinjector = 275 ºC, Tdetector
=

6
Tetrahedron
filtration followed by washed with generous amounts of Et2O
(180 mg, 10 mol% Pd). The mixture was stirred at 60 ºC for 24 h.
ACCEPTED MANUSCRIPT
on the filter.
The catalyst was removed by a magnet and the solvent
evaporated under reduced pressure. The corresponding products
3 or 5 were usually purified by chromatography on silica gel
(hexane/ ethyl acetate).
4.3.2. p-Tolyl(2,4,6-trisopropylphenyl)iodonium
tetrafluoroborate (2b). White solid; yield 1.413 g (56 %); m.p. =
189-191ºC (Hexane); IR (KBr): ν 1585, 1571, 1480, 1463, 1057,
1023, 998, 985 cm-1; H-NMR (300 MHz, DMSO) δ: 1.22 (18H,
4.4.1. 3-Phenylbenzo[b]thiophene (3a)14b. Colourless oil; yield
75 mg (71 %); IR (KBr): ν 1600, 1524, 1484, 1442, 1425, 1348,
1
app. t, J = 6.8 Hz), 2.33 (3H, s), 2.97 (1H, hept, J = 6.8 Hz), 3.40
(2H, hept, J = 6.8 Hz), 7.30 (2H, s), 7.35 (2H, d, J = 8.2 Hz),
7.82 (2H, d, J = 8.4 Hz). 13C-NMR (75 MHz, DMSO) δ: 20.7,
23.5 (2C), 24.0 (4C), 33.3, 38.6 (2C), 111.3, 123.2, 124.5 (2C),
132.5 (2C), 134.0 (2C), 142.2, 151.1 (2C), 154.1. 19F NMR (282
MHz, DMSO): δ -148.3 (br. s), -148.3 (dd, J = 2.3, 1.2 Hz).
HRMS calcd. (%) for C22H30I: 421.1387; found: 421.1368.
1
834 cm-1; H-NMR (300 MHz, CDCl3) δ: 7.40-7.50 (4H, m),
7.50-7.55 (2H, m), 7.60-7.65 (2H, m), 7.90-8.00 (2H, m). 13C-
NMR (75 MHz, CDCl3) δ: 122.90, 122.90, 123.4, 124.3, 124.4,
127.5, 128.7 (4C), 136.0, 137.9, 138.1, 140.7; HRMS calcd. (%)
for C14H11S: 211.0581; found: 211.0573.
4.4.2. 2-Phenylbenzofuran (3b)14b. White solid; yield 96.5 mg (99
%); m.p. = 122-124ºC (Hexane); IR (KBr): ν 1605, 1562, 1491,
4.3.3. o-Tolyl(2,4,6-trisiopropylphenyl)iodonium
1
tetrafluoroborate (2c). White solid; yield 1.573 g (31 %); m.p. =
154-155ºC (Hexane); IR (KBr): ν 1586, 1572, 1560, 1467, 1426,
1058, 979 cm-1; 1H-NMR (300 MHz, DMSO) δ: 1.21 (18H, 2 x d,
J = 6.7 and 6.9 Hz, respectively), 2.63 (3H, s), 2.98 (1H, hept, J =
6.9 Hz), 3.31 (2H, hept, J = 6.9 Hz), 7.25-7.35 (3H, m), 7.50-
7.60 (2H, m), 7.77 (1H, d, J = 7.9 Hz). 13C-NMR (75 MHz,
DMSO) δ: 23.5 (2C), 24.0 (4C), 24.4, 33.3, 38.9 (2C), 119.4,
123.0, 124.8 (2C), 129.6, 132.0, 132.3, 135.4, 140.4, 151.1 (2C),
154.2. 19F NMR (282 MHz, DMSO): δ -148.3 (br. s), -148.3 (dd,
J = 2.3, 1.1 Hz). HRMS calcd. (%) for C22H30I: 421.1387; found:
421.1368.
1471, 1455, 1259, 1020 cm-1; H-NMR (300 MHz, CDCl3) δ:
4
7.02 (1H, d, J = 0.7 Hz), 7.15-7.40 (3H, m), 7.40-7.50 (2H, m),
7.52 (1H, d, J = 8.1 Hz), 7.55-7.60 (1H, m), 7.85-7.90 (2H, m).
13C-NMR (75 MHz, CDCl3) δ: 101.3, 111.2, 120.9, 122.9, 124.2,
124.9 (2C), 128.5, 128.8 (2C), 129.2, 130.4, 154.9, 155.9.
4.4.3. Methyl 2-phenyl-1H-indole-7-carboxylate (3c). White
solid; yield 104.4 mg (83 %); m.p. = 72-74ºC (Hexane); IR
1
(ATR): ν 3435, 1699, 1438, 1268 cm-1; H-NMR (300 MHz,
CDCl3) δ: 3.99 (3H, s), 6.85 (1H, d, J = 2.4 Hz), 7.14 (1H, t, J =
7.7 Hz), 7.30-7.35 (1H, m), 7.40-7.50 (2H, m), 7.70-7.75 (2H,
m), 7.80-7.90 (2H, m), 10.11 (1H, br s). 13C-NMR (75 MHz,
CDCl3) δ: 51.9, 99.5, 112.2, 119.4, 124.2, 125.3 (2C), 126.1,
128.0, 129.0 (2C), 130.3, 131.9, 136.9, 139.0, 168.0. HRMS
calcd. (%) for C16H13NO2: 251.0946; found: 251.0951.
4.3.4. (4-Chlorophenyl)(2,4,6-triisopropylphenyl)iodonium
tetrafluoroborate (2d)14b. White solid; yield 1.572 g (30 %); m.p.
= 180-181ºC (Hexane); IR (KBr): ν 1585, 1570, 1471, 1427,
1
1389, 1369, 1087, 1055, 1011, 817 cm-1; H-NMR (300 MHz,
4.4.4. 5-Fluoro-2-phenyl-1H-indole (3d)30. White solid; yield
83.2 mg (79 %); m.p. = 175-177ºC (Hexane); IR (ATR): ν 3434,
CDCl3) δ: 1.26 (12H, d, J = 6.8 Hz), 1.29 (6H, d, J = 7.0 Hz),
2.79 (1H, hept, J = 6.9 Hz), 3.26 (2H, hept, J = 6.7 Hz), 7.20
(2H, s), 7.42 (2H, d, J = 8.9 Hz), 7.64 (2H, d, J = 8.9 Hz). 13C-
NMR (75 MHz, CDCl3) δ: 23.6 (2C), 24.3 (4C), 32.4, 39.7 (2C),
108.6, 119.7, 125.5 (2C), 132.6 (2C), 133.9 (2C), 139.0, 152.7
(2C), 156.1. 19F NMR (282 MHz, CDCl3): δ -146.7 (br. s), -146.8
(dd, J = 3.3, 1.6 Hz).
1
1624, 1586, 1472, 1457 cm-1; H-NMR (300 MHz, CDCl3) δ:
6.77 (1H, dd, J = 2.0, 0.6 Hz), 6.93 (1H, m), 7.25-7.40 (3H, m),
7.40-7.45 (2H, m), 7.60-7.65 (2H, m), 8.30 (1H, br s). 13C-NMR
4
2
(75 MHz, CDCl3) δ: 100.0 (d, J(C,F) = 4.7 Hz), 105.4 (d, J(C,F)
=
2
3
23.6 Hz), 110.6 (d, J(C,F) = 26.4 Hz), 111.5 (d, J(C,F) = 9.7 Hz),
3
125.2 (2C), 128.0, 129.1 (2C), 129.6 (d, J(C,F) = 10.4 Hz), 132.0,
4.3.5. Bis(4-methoxyphenyl)iodonium tetrafluoroborate (2e)28. m-
CPBA (6 mmol, 1.280 g) was dissolved in CH2Cl2 (20 mL). To
the solution was added 1-iodo-4-methoxybenzene (5.4 mmol,
1.264 g). The mixture was placed then on a pre-heated oil bath at
80 ºC and stirred for 10 min. The mixture was cooled at -78 ºC. A
0 ºC cooled mixture of BF3·OEt2 (13.6 mmol, 1.7 mL) and 4-
methoxybenzeneboronic acid (6 mmol, 912 mg) in 20 mL of
CH2Cl2 was added dropwise. The resulting solution was stirred at
-78 ºC for 30 min Then was allowed to warm to room
temperature and was applied on a silica plug (12 g) and eluted
with CH2Cl2 (2 x 50 mL) followed by CH2Cl2/MeOH (2 x 50
mL). The latter solution was concentrated and diethyl ether (40
mL) was added to the residue to induce precipitation. The
solution was allowed to stir for 15 min, and then the solid was
filtered and washed several times with diethyl ether and then
dried in vacuo. Grey solid; yield 846 mg (37 %); m.p. = 177-
180ºC (Hexane); IR (KBr): ν 1572, 1487, 1441, 1406, 1302,
133.3, 139.6, 158.2 (d, 1J(C,F) = 235.0 Hz).
4.4.5. 4-Bromo-2-phenyl-1H-indole (3e)31. White solid; yield
79.1 mg (58 %); m.p. = 100-102ºC (Hexane); IR (ATR): ν 3443,
1
1597, 1568, 1456, 1452 cm-1; H-NMR (300 MHz, CDCl3) δ:
6.85 (1H, d, J = 1.8 Hz), 7.01 (1H, t, J = 7.9 Hz), 7.25-7.50 (3H,
m), 7.40-7.45 (2H, m), 7.60-7.65 (2H, m), 8.40 (1H, br s). 13C-
NMR (75 MHz, CDCl3) δ: 100.1, 110.0, 114.5, 123.1 (2C), 125.2
(2C), 128.1, 129.0 (2C), 130.0, 131.6, 136.8, 138.4.
4.4.6. 3-(p-Tolyl)benzo[b]thiophene (3f)14a. Colourless oil; yield
42 mg (38 %); IR (NaCl): ν 1532, 1495, 1456, 1425, 1344, 1060,
1021, 819 cm-1; 1H-NMR (300 MHz, CDCl3) δ: 2.43 (3H, s), 7.29
(2H, d, J = 7.8 Hz), 7.35-7.40 (3H, m), 7.48 (2H, d, J = 8.0 Hz),
7.85-8.95 (2H, m). 13C-NMR (75 MHz, CDCl3) δ: 21.2, 122.89,
122.94, 123.0, 124.2, 124.3, 128.6 (2C), 129.4 (2C), 133.1,
137.3, 138.0, 138.1, 140.7.
4.4.7. 2-(p-Tolyl)benzofuran (3g)32. White solid; yield 74 mg (71
%); m.p. = 115-117ºC (Hexane); IR (KBr): ν 1613, 1587, 1504,
1451, 1257, 1033, 801 cm-1; 1H-NMR (300 MHz, CDCl3) δ: 2.38
(3H, s), 6.94 (1H, s), 7.15-7.30 (4H, m), 7.50 (1H, d, J = 7.9 Hz),
7.55 (1H, d, J = 7.0 Hz), 7.75 (2H, d, J = 7.9 Hz). 13C-NMR (75
MHz, CDCl3) δ: 21.4, 100.5, 111.1, 120.7, 122.8, 124.0, 124.9
(2C), 127.8, 129.3, 129.5 (2C), 138.6, 154.8, 156.2.
1
1258, 1177, 1062, 1022, 825 cm-1; H-NMR (300 MHz, DMSO)
δ: 3.80 (6H, s), 7.07 (4H, d, J = 9.2 Hz), 8.13 (4H, d, J = 9.1 Hz).
13C-NMR (75 MHz, DMSO) δ: 55.7 (2C), 105.9 (2C), 117.3
(4C), 136.8 (4C), 161.8 (2C). 19F NMR (282 MHz, DMSO): δ -
148.2 (br. s), -148.3 (dd, J = 2.3, 1.1 Hz).
4.4. General procedure for the direct arylation of heterocycles
4.4.8. 2-(o-Tolyl)benzofuran (3h)33. Colourless oil; yield 69 mg
(66 %); IR (NaCl): ν 1605, 1575, 1489, 1473, 1454, 1259, 1019,
To a stirred solution of the corresponding heterocycle (1 or 4,
0.5 mmol) in ethanol (1.5 mL) were added the corresponding
diaryliodonium tetrafluoroborate (2, 1.5 mmol) and PdO-Fe3O4
1
921, 805 cm-1; H-NMR (300 MHz, CDCl3) δ: 2.56 (3H, s), 6.87
(1H, s), 7.15-7.35 (5H, m), 7.51 (1H, d, J = 7.2 Hz), 7.58 (1H, d,

7
J = 6.7 Hz), 7.75-7.90 (1H, m). 13C-NMR (75 MHz, CDCl3) δ:
21.9, 105.1, 111.1, 120.9, 122.8, 124.2, 126.1, 128.2, 128.5,
129.2, 129.9, 131.2, 135.8, 154.4, 155.7.
reduced pressure. Purification was done by column
ACCEPTED MANUSCRIPT
chromatography using hexane/ethyl acetate (9:1) mixtures to
afford the halo ethers 6.
4.4.9. 2-(4-Chlorophenyl)benzofuran (3i)32. White solid; yield 63
mg (55 %); m.p. = 135-138ºC (Hexane); IR (KBr): ν 1602, 1581,
1487, 1450, 1404, 1256, 1104, 1094, 1031, 1010, 836, 804 cm-1;
4.5.1. 1-Bromo-2-(phenoxymethyl)benzene (6a)37. White solid;
yield 3.085 g (73 %); m.p. = 39-40ºC (Hexane); IR (KBr): ν
1597, 1585, 1570, 1497, 1482, 1447, 1437, 1379, 1303, 1245,
4
1
1H-NMR (300 MHz, CDCl3) δ: 6.99 (1H, d, J = 0.8 Hz), 7.22
1171, 1154, 1056, 1044, 1024, 750 cm-1; H-NMR (300 MHz,
4
4
(1H, td, J = 7.4 Hz, J = 1.2 Hz), 7.29 (1H, td, J = 7.7 Hz, J =
1.6 Hz), 7.40 (2H, d, J = 8.8 Hz), 7.45-7.50 (1H, m), 7.55-7.60
(1H, m), 7.77 (2H, d, J = 8.7 Hz). 13C-NMR (75 MHz, CDCl3) δ:
101.7, 111.2, 121.0, 123.1, 124.5, 126.1 (2C), 128.98, 129.02
(2C), 129.05, 134.3, 154.8, 154.9.
CDCl3) δ: 5.14 (2H, s), 6.95-7.00 (3H, m), 7.15-7.20 (1H, m),
7.25-7.35 (3H, m), 7.55-7.60 (2H, m). 13C-NMR (75 MHz,
CDCl3) δ: 69.3, 114.9 (2C), 121.2, 122.2, 127.5, 128.8, 129.1,
129.5 (2C), 132.6, 136.4, 158.4.
4.5.2. 1-Bromo-2-((4-methoxyphenoxy)methyl)benzene
(6b)38.
4.4.10. 2-(4-Methoxyphenyl)benzofuran (3j)32. White solid; yield
94 mg (84 %); m.p. = 147-148ºC (Hexane); IR (KBr): ν 1610,
Colourless oil; yield 679 mg (93 %); IR (NaCl): ν 1593, 1570,
1506, 1465, 1455, 1441, 1381, 1230, 1108, 1042, 823, 749 cm-1;
1H-NMR (300 MHz, CDCl3) δ: 3.76 (3H, s), 5.08 (2H, s), 6.84
(2H, d, J = 9.3 Hz), 6.92 (2H, d, J = 9.3 Hz), 7.17 (1H, dd, J =
7.9 Hz, 4J = 1.7 Hz), 7.32 (1H, dd, J = 7.5 Hz, 4J = 1.2 Hz), 7.56
(2H, app. t, J = 7.3 Hz). 13C-NMR (75 MHz, CDCl3) δ: 55.7,
70.1, 114.7 (2C), 115.9 (2C), 122.3, 127.5, 128.9, 129.1, 132.6,
136.6, 152.6, 154.2.
1
1593, 1505, 1453, 1440, 1248, 1180, 1023, 835, 799 cm-1; H-
NMR (300 MHz, CDCl3) δ: 3.82 (3H, s), 6.85 (1H, s), 6.95 (2H,
d, J = 8.5 Hz), 7.15-7.30 (2H, m), 7.49 (1H, d, J = 7.6 Hz), 7.53
(1H, d, J = 7.1 Hz), 7.78 (2H, d, J = 8.4 Hz). 13C-NMR (75 MHz,
CDCl3) δ: 55.3, 99.7, 111.0, 114.2 (2C), 120.5, 122.8, 123.3,
123.7, 126.4 (2C), 129.5, 154.7, 156.0, 160.0.
4.4.11. 3-Phenylthiophene (5a)14b. White solid; yield 12.2 mg (15
%); m.p. = 91-92ºC (Hexane); IR (ATR): ν 3059, 3033, 1597,
4.5.3. 1-Bromo-2-((p-tolyloxy)methyl)benzene (6c)37. Colourless
oil; yield 605 mg (96 %); IR (NaCl): ν 1586, 1570, 1510, 1441,
1
1
1530, 1493 cm-1; H-NMR (300 MHz, CDCl3) δ: 7.25-7.40 (2H,
1380, 1297, 1239, 1044, 1025, 817, 747 cm-1; H-NMR (300
m), 7.40-7.50 (4H, m) 7.60-7.65 (2H, m). 13C-NMR (75 MHz,
CDCl3) δ: 120.3, 126.2, 126.3, 126.4 (2C), 127.2, 128.8 (2C),
135.9, 142.4.
4.4.12. 3,4-Diphenylthiophene (5a’)14b. White solid; yield 29.0
mg (24 %); m.p. = 112-114ºC (Hexane); IR (ATR): ν 3049, 3023,
1670, 1598, 1508 cm-1; 1H-NMR (300 MHz, CDCl3) δ: 7.15-7.25
(10H, m), 7.31 (2H, s). 13C-NMR (75 MHz, CDCl3) δ: 124.0,
126.9. 128.1 (2C), 129.0 (2C), 136.5, 141.7.
MHz, CDCl3) δ: 2.28 (3H, s), 5.09 (2H, s), 6.87 (2H, d, J = 8.5
4
Hz), 7.08 (2H, d, J = 8.6 Hz), 7.15 (1H, dd, J = 7.7 Hz, J = 1.5
4
Hz), 7.30 (1H, dd, J = 7.6 Hz, J = 0.8 Hz), 7.50-7.60 (2H, m).
13C-NMR (75 MHz, CDCl3) δ: 20.5, 69.5, 114.7 (2C), 122.2,
127.5, 128.8, 129.1, 129.9 (2C), .130.4, 132.5, 136.6, 156.3.
4.5.4. 1-Bromo-2-((4-chlorophenoxy)methyl)benzene
(6d)37.
Colourless oil; yield 667 mg (90 %); IR (NaCl): ν 1599, 1493,
1
1439, 1291, 1249, 1174, 1096, 1044 cm-1; H-NMR (300 MHz,
CDCl3) δ: 5.10 (2H, s), 6.90 (2H, d, J = 9.0 Hz), 7.18 (1H, td, J =
4.4.13. 2-Bromo-4-phenylthiophene (5b)30. White solid; yield
21.5 mg (18 %); m.p. = 48-50ºC (Hexane); IR (ATR): ν 3082,
4
7.9 Hz, J = 1.7 Hz), 7.24 (2H, d, J = 9.1 Hz), 7.32 (1H, td, J =
4
7.6 Hz, J = 1.1 Hz), 7.51 (1H, d, J = 7.7 Hz), 7.58 (1H, dd, J =
1
3057, 1596, 1492, 1446 cm-1; H-NMR (300 MHz, CDCl3) δ:
4
7.9 Hz, J = 1.1 Hz). 13C-NMR (75 MHz, CDCl3) δ: 69.7, 116.2
7.30-7.35 (3H, m), 7.35-7.40 (2H, m), 7.50-7.55 (2H, m). 13C-
NMR (75 MHz, CDCl3) δ: 112.9, 121.4, 126.2 (2C), 127.6, 128.9
(2C), 129.2, 134.9, 142.8.
(2C), 122.3, 126.1, 127.6, 128.8, 129.36, 129.41 (2C), 132.7,
135.9, 157.0.
4.5.5. 1-Bromo-2-((4-fluorophenoxy)methyl)benzene (6e)37. Pale
yellow oil; yield 540 mg (77 %); IR (NaCl): ν 1602, 1571, 1505,
1469, 1440, 1381, 1298, 1247, 1220, 1097, 1044, 1025, 827 cm-1;
1H-NMR (300 MHz, CDCl3) δ: 5.09 (2H, s), 6.85-7.05 (4H, m),
7.18 (1H, td, J = 7.9 Hz, 4J = 1.7 Hz), 7.32 (1H, td, J = 7.6 Hz, 4J
= 1.2 Hz), 7.52 (1H, d, J = 7.7 Hz), 7.57 (1H, dd, J = 7.9 Hz, 4J =
4.4.14. 3-Bromo-4-phenylthiophene (5c)34. White solid; yield
60.9 mg (51 %); m.p. = 57-59ºC (Hexane); IR (ATR): ν 3058,
1
3030, 1600, 1523, 1482 cm-1; H-NMR (300 MHz, CDCl3) δ:
7.24 (1H, d, J = 3.5 Hz), 7.35 (1H, d, J = 3.5 Hz), 7.40-7.45 (3H,
m), 7.45-7.50 (2H, m). 13C-NMR (75 MHz, CDCl3) δ: 111.0,
123.4, 124.0, 127.8, 128.2 (2C), 129.0 (2C), 135.1, 142.0.
4.4.15. 4-Phenyl-2,2’-bithiophene (5d)35. Pale brown solid; yield
58.1 mg (48 %); m.p. = 72-74ºC (Hexane); IR (ATR): ν 3063,
3029, 1596, 1491 cm-1; 1H-NMR (300 MHz, CDCl3) δ: 7.02 (1H,
dd, J = 5.0, 3.7 Hz), 7.20-7.25 (2H, m), 7.30-7.35 (2H, m), 7.35-
7.40 (2H, m), 7.44 (1H, d, J = 1.4 Hz), 7.55-7.65 (2H, m). 13C-
NMR (75 MHz, CDCl3) δ: 119.1, 122.9, 123.9, 124.5, 126.3
(2C), 127.3, 127.8, 128.8 (2C), 135.5, 137.3, 138.0, 142.9.
2
1.1 Hz). 13C-NMR (75 MHz, CDCl3) δ: 70.1, 115.9 (2C, d, J(C,F)
3
= 21.2 Hz), 116.0 (2C, d, J(C,F) = 10.0 Hz), 122.3, 127.6, 128.9,
4
1
129.3, 132.6, 136.1, 154.6 (d, J(C,F) = 2.1 Hz), 157.5 (d, J(C,F)
=
238.8 Hz). 19F NMR (282 MHz, CDCl3): δ -123.3 (tt, 3J(H,F) = 8.0
Hz, , 4J(H,F) = 4.5).
4.5.6. 1-Bromo-2-((3-fluorophenoxy)methyl)benzene (6f)38. Pale
yellow oil; yield 616 mg (88 %); IR (NaCl): ν 1611, 1595, 1490,
1
1440, 1280, 1263, 1166, 1136, 1027, 748 cm-1; H-NMR (300
MHz, CDCl3) δ: 5.18 (2H, s), 6.85-7.15 (4H, m), 7.17 (1H, td, J
4.5. General procedure for the preparation of the haloethers (6)
4
4
= 7.9 Hz, J = 1.7 Hz), 7.32 (1H, td, J = 7.6 Hz, J = 1.2 Hz),
7.55-7.65 (2H, m). 13C-NMR (75 MHz, CDCl3) δ: 70.6, 115.7 (d,
4J(C,F) = 1.6 Hz), 116.3 (d, 2J(C,F) = 18.2 Hz), 121.7 (d, 2J(C,F) = 6.9
Hz), 122.1, 124.3 (d, 3J(C,F) = 3.9 Hz), 127.6, 128.8, 129.3, 132.5,
The haloethers were prepared following the procedure
described by Fagnou et al.36
To a mixture of potassium carbonate (5 mmol, 690 mg) and
the appropriate phenol (5 mmol), was added acetone (5 mL). To
the stirring mixture was added the required benzyl bromide (2.5
mmol) followed by heating to 50 ºC overnight. The reaction
mixture was then cooled to room temperature, poured into a
solution of NaOH (2M), and extracted three times with ether. The
organic extracts were dried over MgSO4 and concentrated under
3
1
135.9, 146.5 (d, J(C,F) = 10.6 Hz), 152.9 (d, J(C,F) = 246.0 Hz).
19F NMR (282 MHz, CDCl3): δ -133.9 (m).
4.5.7. 1-Bromo-2-((2-fluorophenoxy)methyl)benzene
(6g)39.
Colourless oil; yield 576 mg (82 %); IR (NaCl): ν 1591, 1571,
1504, 1456, 1442, 1380, 1313, 1284, 1260, 1206, 1110, 1024,
745 cm-1; 1H-NMR (300 MHz, CDCl3) δ: 5.11 (2H, s), 6.60-6.80

8
Tetrahedron
ACCEPTED MANUSCRIPT
4
(3H, m), 7.15-7.25 (2H, m), 7.33 (1H, td, J = 7.6 Hz, J = 1.2
7.53 (1H, d, J = 1.7 Hz), 7.68 (1H, d, J = 7.6 Hz). 13C-NMR (75
MHz, CDCl3) δ: 20.9, 68.5, 117.1, 121.9, 122.6, 123.6, 124.6,
127.5, 128.3, 130.1, 130.3, 131.3, 131.6, 152.6.
4
Hz), 7.52 (1H, d, J = 7.7 Hz), 7.58 (1H, dd, J = 7.9 Hz, J = 1.1
Hz). 13C-NMR (75 MHz, CDCl3) δ: 69.6, 102.8 (d, J(C,F) = 24.9
2
Hz), 108.1 (d, 3J(C,F) = 21.4 Hz), 110.6 (d, 4J(C,F) = 2.9 Hz), 122.3,
4.6.4. 2-Chloro-6H-benzo[c]chromene (7d)37. Colourless oil;
yield 93 mg (86 %); IR (NaCl): ν 2842, 1591, 1487, 1445, 1408,
3
127.6, 128.9, 129.4, 130.3 (d, J(C,F) = 10.0 Hz), 132.7, 135.8,
.159.8 (d, J(C,F) = 10.9 Hz), 163.6 (d, J(C,F) = 245.5 Hz). 19F
2
1
1249, 1259, 1247, 1200, 1093, 1020, 815 cm-1; H-NMR (300
1
NMR (282 MHz, CDCl3): δ -111.4 (m).
MHz, CDCl3) δ: 5.10 (2H, s), 6.91 (1H, d, J = 8.6 Hz), 7.14 (1H,
d, J = 7.5 Hz), 7.17 (1H, dd, J = 8.6 Hz, J = 2.5 Hz), 7.30 (1H,
td, J = 7.4 Hz, J = 1.3 Hz), 7.38 (1H, td, J = 7.6 Hz, J = 1.4
Hz), 7.64 (1H, d, J = 7.5 Hz), 7.67 (1H, d, J = 2.5 Hz). 13C-NMR
(75 MHz, CDCl3) δ: 68.5, 118.7, 122.1, 123.1, 124.3, 124.7,
127.1, 128.3, 128.6, 129.1, 131.3 (2C), 153.3.
4
4.5.8. 1-Bromo-2-(phenoxymethyl)-4-(trifluoromethyl)benzene
(6h). White solid; yield 823 mg (99 %); m.p. = 70-72ºC
(Hexane); IR (KBr): ν 1600, 1586, 1498, 1484, 1459, 1449,
1417, 1342, 1304, 1248, 1173, 1154, 1128, 1060, 1022, 904, 831
cm-1; 1H-NMR (300 MHz, CDCl3) δ: 5.10 (2H, s), 6.95-7.05 (3H,
m), 7.31 (2H, t, J = 7.8 Hz), 7.41 (1H, d, J = 8.3 Hz), 7.67 (1H, d,
J = 8.3 Hz), 7.86 (1H, s). 13C-NMR (75 MHz, CDCl3) δ: 68.8,
4
4
4.6.5. 2-Fluoro-6H-benzo[c]chromene (7e)37. Colourless oil;
yield 92 mg (92 %); IR (NaCl): ν 2842, 1619, 1577, 1495, 1448,
1426, 1285, 1247, 1173, 1021, 902, 867, 815 cm-1; 1H-NMR (300
MHz, CDCl3) δ: 5.08 (2H, s), 6.85-6.95 (2H, m), 7.14 (1H, d, J =
7.3 Hz), 7.30 (1H, t, J = 7.4 Hz), 7.35-7.40 (2H, m), 7.60 (1H, d,
1
3
114.9 (2C), 121.6, 123.8 (q, J(C,F) = 272.4 Hz), 125.5 (q, J(C,F)
=
3.8 Hz), 125.73, 125.74 (q, 3J(C,F) = 3.8 Hz), 129.6 (2C), 130.2 (q,
2J(C,F) = 33.0 Hz), 133.1, 137.7, 158.1. 19F NMR (282 MHz,
CDCl3): δ -62.6 (s).
J = 7.7 Hz). 13C-NMR (75 MHz, CDCl3) δ: 68.5, 109.6 (d, J(C,F)
2
4.5.9. 2-Bromo-4-fluoro-1-(phenoxymethyl)benzene
(6i).
= 24.2 Hz), 115.8 (d, 2J(C,F) = 23.5 Hz), 118.4 (d, 3J(C,F) = 8.3 Hz),
3
Colourless oil; yield 548 mg (78 %); IR (NaCl): ν 1601, 1496,
122.2, 124.1 (d, J(C,F) = 8.1 Hz), 124.7, 128.3, 128.5, 129.4 (d,
1457, 1304, 1238, 1171, 1054, 1032, 812, 752 cm-1; H-NMR
4J(C,F) = 2.2 Hz), 131.5, 150.7 (d, J(C,F) = 2.0 Hz), 158.2 (d, 1J(C,F)
1
4
(300 MHz, CDCl3) δ: 5.08 (2H, s), 6.90-7.10 (4H, m), 7.25-7.35
= 238.9 Hz). 19F NMR (282 MHz, CDCl3): δ -121.5.
(3H, m), 7.52 (1H, dd, J = 8.6, 6.0 Hz). 13C-NMR (75 MHz,
4.6.6. 1-Fluoro-6H-benzo[c]chromene (7f) and 3-Fluoro-6H-
benzo[c]chromene (7f’) (45:55). Colourless oil; yield 89 mg (89
%); IR (NaCl): ν 2842, 1618, 1591, 1508, 1486, 1459, 1440,
1262, 1144, 1039, 1025, 966, 793, 763 cm-1; 1H-NMR (300 MHz,
CDCl3) δ: 5.07 (2H, s), 5.12 (2H, s), 6.65-6.85 (4H, m), 7.10-
7.20 (3H, m), 7.25-7.45 (4H, m), 7.63 (1H, d, J = 7.8 Hz), 7.67
(1H, dd, J = 8.6, 6.4 Hz), 8.04 (1H, d, J = 7.8 Hz). 13C-NMR (75
2
CDCl3) δ: 68.8,.114.7 (d, J(C,F) = 21.0 Hz), 114.9 (2C), 119.9 (d,
2J(C,F) = 24.6 Hz), 121.3, 122.4 (d, J(C,F) = 9.6 Hz), 129.6 (2C),
3
130.0 (d, 3J(C,F) = 8.5 Hz), 132.3 (d, 4J(C,F) = 3.5 Hz), 158.3, 161.9
(d, J(C,F) = 250.6 Hz). 19F NMR (282 MHz, CDCl3): δ -112.5
1
(m).
4.6. General procedure for the intramolecular direct arylation
2
MHz, CDCl3) δ: 68.7, 68.8, 104.8 (d, J(C,F) = 24.3 Hz), 109.3 (d,
2J(C,F) = 22.0 Hz), 109.7 (d, J(C,F) = 23.3 Hz), 112.3 (d, J(C,F)
=
2
3
To a stirred solution of the corresponding arene (6, 0.5 mmol)
in N,N-dimethylacetamide (2 mL) were added KOAc (1 mmol,
98 mg) and PdO-Fe3O4 (180 mg, 10 mol% Pd). The mixture was
stirred at 140 ºC for 48 h. The catalyst was removed by a magnet
and the mixture was quenched with water and extracted with
ethyl acetate (3 x 10 mL). The organic phases were dried over
MgSO4, followed by evaporation under reduced pressure to
remove the solvent. The corresponding products 7 were usually
purified by chromatography on silica gel (hexane/ ethyl acetate).
4
4
13.7 Hz), 113.1 (d, J(C,F) = 3.2 Hz), 119.2 (d, J(C,F) = 3.2 Hz),
3
121.7, 124.4 (d, J(C,F) = 10.0 Hz), 124.6, 124.7, 126.2, 126.3,
127.0 (d, 4J(C,F) = 3.0 Hz), 127.5, 127.9 (d, 4J(C,F) = 1.1 Hz), 128.5,
129.0 (d, 3J(C,F) = 11.1 Hz), 129.5, 130.4, 131.5, 156.0 (d, 3J(C,F)
=
12.1 Hz), 156.6 (d, 3J(C,F) = 6.6 Hz), 160.7 (d, J(C,F) = 250.7 Hz),
1
163.3 (d, J(C,F) = 247.3 Hz) . 19F NMR (282 MHz, CDCl3): δ -
1
111.5 (m), 115.1 (m). HRMS calcd. (%) for C13H8FO: 199.0559;
found: 199.0551.
4.6.1. 6H-Benzo[c]chromene (7a)36. Colourless oil; yield 71 mg
(78 %); IR (NaCl): ν 2842, 1607, 1594, 1487, 1440, 1245, 1198,
1018, 755 cm-1; 1H-NMR (300 MHz, CDCl3) δ: 5.09 (2H, s), 6.98
4.6.7. 4-Fluoro-6H-benzo[c]chromene (7g). Colourless oil; yield
87 mg (87 %); IR (NaCl): ν 2843, 1617, 1593, 1575, 1488, 1467,
1
1438, 1299, 1279, 1258, 1221, 1014, 900, 753 cm-1; H-NMR
4
4
3
(1H, dd, J = 8.1 Hz, J = 1.2 Hz), 7.03 (1H, td, J = 7.5 Hz, J =
1.3 Hz), 7.11 (1H, d, J = 7.4 Hz), 7.20-7.25 (2H, m), 7.34 (1H,
(300 MHz, CDCl3) δ: 5.19 (2H, s), 6.97 (1H, td, J(H,H) = 8.0 Hz,
4J(H,F) = 5.1 Hz), 7.04 (1H, ddd, 3J(H,F) = 10.1 Hz, 3J(H,H) = 8.1 Hz,
4
4J(H,H) = 1.6 Hz), 7.17 (1H, d, 3J(H,H) = 7.4 Hz), 7.31 (1H, td, 3J(H,H)
td, J = 7.6 Hz, J = 1.4 Hz), 7.67 (1H, d, J = 7.5 Hz), 7.71 (1H,
dd, J = 7.7 Hz, 4J = 1.6 Hz). 13C-NMR (75 MHz, CDCl3) δ: 68.4,
117.3, 122.0, 122.1, 122.9, 123.3, 124.6, 127.6, 128.4, 129.4,
130.1, 131.4, 154.8.
3
= 7.4 Hz, 4J(H,H) = 1.3 Hz), 7.39 (1H, td, J(H,H) = 7.4 Hz, 4J(H,H)
=
3
4
5
1.3 Hz), 7.49 (1H, dt, J(H,H) = 7.8 Hz, J(H,H) = J(H,F) = 1.3 Hz),
7.68 (1H, d, J(H,H) = 7.5 Hz). 13C-NMR (75 MHz, CDCl3) δ:
3
68.7, 115.9 (d, 2J(C,F) = 18.2 Hz), 118.4 (d, 4J(C,F) = 3.5 Hz), 121.6
4.6.2. 2-Methoxy-6H-benzo[c]chromene (7b)38. Colourless oil;
yield 79 mg (75 %); IR (NaCl): ν 2835, 1614, 1572, 1496, 1450,
3
4
(d, J(C,F) = 7.2 Hz), 122.3, 124.8, 125.4 (d, J(C,F) = 2.1 Hz),
3
2
1
1219, 1194, 1049, 1037 cm-1; H-NMR (300 MHz, CDCl3) δ:
128.2, 128.6, 129.3 (d, J(C,F) = 3.2 Hz), 131.1, 142.6 (d, J(C,F)
=
11.5 Hz), 152.1 (d, J(3C,F) = 245.5 Hz). 19F NMR (282 MHz,
1
3.84 (3H, s), 5.07 (2H, s), 6.81 (1H, dd, J = 8.8 Hz, 4J = 2.9 Hz),
6.94 (1H, d, J = 8.8 Hz), 7.16 (1H, d, J = 7.4 Hz), 7.25-7.30 (2H,
4
5
CDCl3): δ -136.0 (ddd, J(H,F) = 10.2 Hz, J(H,F) = 5.2 Hz, J(H,F)
=
4
1.1 Hz). HRMS calcd. (%) for C13H8FO: 199.0559; found:
199.0559.
m with td at 7.30, J = 7.4 Hz, J = 1.2 Hz), 7.38 (1H, td, J = 7.6
4
Hz, J = 1.3 Hz), 7.66 (1H, d, J = 7.5 Hz). 13C-NMR (75 MHz,
4.6.8. 8-(Trifluoromethyl)-6H-benzo[c]chromene (7h)40. White
solid; yield 105 mg (87 %); m.p. = 68-70 ºC (Hexane); IR
(NaCl): ν 2851, 1607, 1483, 1424, 1333, 1246, 1164, 1076, 757
cm-1; 1H-NMR (300 MHz, CDCl3) δ: 5.14 (2H, s), 7.02 (1H, dd, J
= 8.1 Hz, J = 0.9 Hz), 7.08 (1H, td, J = 7.6 Hz, J = 1.2 Hz),
7.30 (1H, td, J = 7.8 Hz, 4J = 1.5 Hz), 7.41 (1H, s), 7.61 (1H, d, J
= 8.3 Hz), 7.74 (1H, dd, J = 8.0 Hz, 4J = 1.5 Hz), 7.77 (1H, d, J =
9.0 Hz). 13C-NMR (75 MHz, CDCl3) δ: 68.0, 117.6, 121.6, 121.7
CDCl3) δ: 55.8, 68.6, 108.3, 115.0, 118.0, 122.1, 123.6, 124.7,
127.8, 128.4, 130.2, 131.9, 148.9, 154.8.
4.6.3. 2-Methyl-6H-benzo[c]chromene (7c)37. Colourless oil;
yield 84 mg (86 %); IR (NaCl): ν 2840, 1607, 1593, 1573, 1498,
4
4
1
1449, 1246, 1199, 1021 cm-1; H-NMR (300 MHz, CDCl3) δ:
2.36 (3H, s), 5.08 (2H, s), 6.88 (1H, d, J = 8.2 Hz), 7.03 (1H, dd,
J = 8.2 Hz, 4J = 2.0 Hz), 7.13 (1H, d, J = 7.4 Hz), 7.26 (1H, td, J
4
4
= 7.4 Hz, J = 1.2 Hz), 7.36 (1H, td, J = 7.6 Hz, J = 1.1 Hz),

9
3
1
D.; Glorius, F. Chem. Sci. 2015, 6, 1816–1824; (d) Hayashi, S.;
Kojima, Y.; Koizumi, T. Polym. Chem. 2015, 6, 881–885.
(q, J(C,F) = 3.8 Hz), 122.3, 122.4, 123.8, 124.1 (q, J(C = 272.1
ACCE,F)PTED MANUSCRIPT
Hz), 125.3 (q, 3J(C,F) = 3.8 Hz), 129.5 (q, 2J(C,F) = 32.6 Hz), 130.7,
15. Malmgren, J.; Nagendiran, A.; Tai, C.-W.; Bäckvall, J.-E.;
Olofsson, B. Chem. Eur. J. 2014, 20, 13531–13535.
131.8, 133.7, 155.1. 19F NMR (282 MHz, CDCl3): δ -62.5.
4.6.9. 9-Fluoro-6H-benzo[c]chromene (7i)41. Colourless oil;
yield 77 mg (77 %); IR (NaCl): ν 2846, 1598, 1574, 1504, 1455,
16. Lee, J.; Chung, J.; Moon Byun, S.; Moon Kim, B.; Lee, C.
Tetrahedron 2013, 69, 5660–5664.
17. Baumann, C. G.; De Ornellas, S.; Reeds, J. P.; Storr, T. E.;
Williams, T. J. Fairlamb, I. J. S. Tetrahedron 2014, 70, 6174.
18. (a) Zhang, W.; Zeng, Q,; Zhang, X.; Tian, Y.; Yue, Y.; Guo, Y.;
Wang, Z. J. Org. Chem. 2011, 76, 4741–4745. Zhang, W.; Tian,
Y.; Zhao, N.; Wang, Y.; Li, J.; Wang, Z. Tetrahedron 2014, 70,
6120–6126; (c) Keshipour, S.; Shaabani, A. Appl. Organometal.
Chem. 2014, 28, 116–119; (c) Le, H. T. N.; Nguyen, T. T.; Vu, P.
H. L.; Truong, T.; Phan, N. T. S. J. Mol. Catal. A: Chem. 2014,
391, 74–82.
19. Phan, N. T. S.; Nguyen, C. K.; Nguyen, T. T.; Truong, T. Catal.
Sci. Technol. 2014, 4, 369–377.
20. Zoeller, J.; Fabry, D. C.; Rueping, M. ACS Catal. 2015, 5, 3900–
3904.
1
1422, 1246, 1180, 1040, 1015, 757 cm-1; H-NMR (300 MHz,
CDCl3) δ: 5.07 (2H, s), 6.90-7.15 (4H, m), 7.20-7.30 (1H, m),
3
4
7.35 (1H, dd, J(H,F) = 9.9 Hz, J(H,H) = 2.5 Hz), 7.63 (1H, dd,
3J(H,H) = 7.7 Hz, J(H,H) = 1.5 Hz). 13C-NMR (75 MHz, CDCl3) δ:
67.9, 109.0 (d, J(C,F) = 23.2 Hz), 114.3 (d, J(C,F) = 22.1 Hz),
4
2
2
4
3
117.5, 122.1 (d, J(4C,F) = 2.5 Hz), 122.3, 123.5, 126.2 (d, J(C,F)
=
3
8.5 Hz), 127.0 (d, J(C,F) = 2.9 Hz), 130.1, 132.3 (d, J(C,F) = 8.3
Hz), 154.7, 163.1 (d, J(C,F) = 244.8 Hz). 19F NMR (282 MHz,
1
CDCl3): δ -113.5 (m).
Acknowledgements
21. Liu, H.; Yin, B.; Gao, Z.; Li, Y.; Jiang, H. Chem. Commun. 2012,
48, 2033–2035.
The authors thank the Irish Research Council (RC), Science
Foundation Ireland (SFI/12/IP/1315 and SFI/12/RC/2275),
Spanish Ministerio de Economía y Competitividad (MICINN;
CTQ2011-24151, University of Alicante and MICINN FPI
program (JMP).
22. (a) Martínez, R.; Ramón, D. J.; Yus, M. Adv. Synth. Catal. 2008,
350, 1235–1240; (b) Martínez, R.; Ramón, D. J.; Yus, M. Org.
Biomol. Chem. 2009, 7, 2176–2181; (c) Cano, R.; Ramón, D. J.;
Yus, M. Synlett 2011, 2017–2020; (d) Cano, R.; Yus, M.; Ramón,
D. J. Tetrahedron 2013, 69, 7056–7065.
23. (a) Aliaga, M. J.; Ramón, D. J.; Yus, M. Org. Biomol. Chem.
2010, 8, 43–46; (b) Cano, R.; Ramón, D. J.; Yus, M. J. Org.
Chem. 2010, 75, 3458–3460; (c) Cano, R.; Ramón, D. J.; Yus, M.
Tetrahedron 2011, 67, 5432–5436; (d) Cano, R.; Ramón, D. J.;
Yus, M. J. Org. Chem. 2011, 76, 5547–5557; (e) Cano, R.; Yus,
M.; Ramón, D. J. Tetrahedron 2011, 67, 8079–8085; (f) Cano, R.;
Yus, M.; Ramón, D. J. Tetrahedron 2012, 68, 1393–1400; (g)
Cano, R.; Yus, M.; Ramón, D. J. ACS Catal. 2012, 2, 1070–1078;
(h) Cano, R.; Yus, M.; Ramón, D. J. Chem. Commun. 2012, 48,
7628–7630; (i) Pérez, J. M.; Cano, R.; Yus, M.; Ramón, D. J. Eur.
J. Org. Chem. 2012, 4548–4554; (j) Pérez, J. M.; Cano, R.; Yus,
M.; Ramón, D. J. Synthesis 2013, 45, 1373–1379; Cano, R.; Pérez,
J. M.; Ramón, D. J. Appl. Catal. A: Gen. 2014, 470, 177–182; (k)
Pérez, J. M.; Cano, R.; Ramón, D. J. RSC Adv. 2014, 4, 23943–
23951; (l) Pérez, J. M.; Ramón, D. J. Adv. Synth. Catal. 2014, 356,
3039–3047; m) Marset, X.; Pérez, J. M.; Ramón, D. J. Green
Chem. 2015, DOI 10.1039/C56C01745A.
Supplementary data
Catalyst full characterisation data can be found at the
supplementary data associated with article.
References and notes
1. Horton, D. A.; Bourne, G. T.; Smythe, M. L. Chem. Rev. 2003,
103, 893–930.
2. Negishi, E. Handbook of Organopalladium Chemistry for Organic
Synthesis, Wiley: New York, 2003.
3. (a) Alberico, D.; Scott, M. E.; Lautens, M. Chem. Rev. 2007, 107,
174–238; (b) Ackermann, L.; Vicente, R.; Kapdi, A. R. Angew.
Chem. Int. Ed. 2009, 48, 9792–9826; (c) McGlacken, G. P.;
Bateman, L. M. Chem. Soc. Rev. 2009, 38, 2447–2464.
4. Godula, K.; Sames, D. Science 2006, 312, 67–72.
5. (a) Trost, B. M.; Science 1991, 254, 1471–1477; (b) Green
Chemistry: Designing Chemistry for the Environment; Anastas, P.
T.; Williamson, T. C., Eds.; American Chemical Society:
Washington, DC, 1996; (c) Trost, B. M. Acc. Chem. Res. 2002,
35, 695-705; (d) Sheldon, R. A.; Arends, I; Hanefeld, U. Green
Chemistry and Catalysis, Wiley–VCH: Weinheim, Germany,
2007; (e) Guillena, G.; Ramón, D. J.; Yus M. Angew. Chem. Int.
Ed. 2007, 46, 2358–2364; (f) Guillena, G.; Ramón, D. J.; Yus M.
Chem. Rev. 2010, 110, 1611–1641.
6. For recent reviews see: (a) Mousseau, J. J.; Charette, A. B. Acc.
Chem. Res. 2013, 45, 412–424; (b) Shibahara, F.; Murai, T. Asian
J. Org. Chem. 2013, 8, 624–636; (c) Yuan, K; Doucet, H.
ChemCatChem 2013, 5, 3495–3496; (d) Rossi, R.; Bellina, F.;
Lessi, M.; Manzini, C. Adv. Synth. Catal. 2014, 356, 17–117; (e)
Rossi, R.; Bellina, F.; Lessi, M.; Manzini, C; Perego, L. A.
Synthesis 2014, 46, 2833–2883; (f) El Kazzouli, S.; Koubachi, J.;
El Brahmi, N.; Guillaumet, G. RSC Adv. 2015, 5, 15292–15327;
(g) Liang, Y.; Wnuk, S. F. Molecules 2015, 20, 4874–4901.
7. de Vries, J. G. Dalton Trans. 2006, 421–429.
8. Garret, C. E.; Prasad, K. Adv. Synth. Catal. 2004, 346, 889–900.
9. Ross, J. Heterogeneous Catalysis Fundamentals and Applications,
Elsevier: Amsterdam, 2012.
10. Cano, R.; Schmidt, A. F.; McGlacken, G. P. Chem. Sci. 2015, 6,
5338–5346.
11. (a) Djakovitch, L.; Dufaud, V.; Zaidi, R. Adv. Synth. Catal. 2006,
348, 715–724; (b) Cusati, G.; Djakovitch, L. Tetrahedron Lett.
2008, 49, 2499–2502;
12. (a) Wang, L.; Yi, W.-b.; Cai, C. Chem. Commun. 2011, 47, 806–
808.; (b) Areephong, J.; Hendsbee, A. D.; Welch, G. C. New J.
Chem. 2015, 39, 6714–6717.
24. Collins, G.; Schmidt, M:, O’Dwyer, C; Holmes, J. D.; McGlacken,
G. P. Angew. Chem. Int. Ed. 2014, 53, 4142–4145.
25. Pal, J.; Pal, T. Nanoscale 2015, 7, 14159–14190.
26. (a) van de Sandt, E. J. A. X.; Wiersma, A.; Makkee, M.; van
Bekkum, H.; Moulijn, J. A. Appl. Catal. A Gen. 1998, 173, 161–
173; (b) Urbano, F. J.; Marinas, J. M. J. Mol. Catal. A Chem.
2001, 173, 329–345; (c) Kar, P.; Mishra, B. G. J. Clust. Sci. 2014,
25, 1463–1478.
27. Campeau, L.; Fagnou, K. Chem. Commun. 2006, 1253–1264.
28. Bielawski, M.; Aili, D.; Olofsson, B. J. Org. Chem. 2008, 73,
4602–4607.
29. Phipps, R. J.; Grimster, N. P.; Gaunt, M. J. J. Am. Chem. Soc.
2008, 130, 8172–8174.
30. Funaki, K.; Sato, T.; Oi, S. Org. Lett. 2012, 14, 6186–6189.
31. Guilarte, V.; Castroviejo, M. P.; García-García, P.; Fernández-
Rodríguez, M. A.; Sanz, R. J. Org. Chem. 2011, 76, 3416–3437.
32. Rao, M. L. N.; Jadhav, D. N.; Dasgupta, P. Eur. J. Org. Chem.
2013, 781–788.
33. Denmark, S. E.; Smith, R. C.; Chang, W.-T. T.; Muhuhi, J. M. J.
Am. Chem. Soc. 2009, 131, 3104–3118.
34. Schnapperelle, I.; Bach, T. ChemCatChem 2013, 5, 3232-3236.
35. Varello, S.; Handy, S. T. Synthesis 2009, 1, 138-142.
36. Parisien, M.; Valette, D.; Fagnou, K. J. Org. Chem. 2005, 70,
7578–7584.
37. Sun, C.-L.; Gu, Y.-F.; Huang, W.-P.; Shi, Z.-J. Chem. Commun.
2011, 47, 9813–9815.
38. Campeau, L.-C.; Parisien, M.; Jean, A.; Fagnou, K. J. Am. Chem.
Soc. 2006, 128, 581–590.
39. Barluenga, J.; Fañanás, F. J.; Sanz, R.; Fernández, Y. Chem. Eur.
J. 2002, 8, 2034–2046.
40. Manley, D. W.; McBurney, R. T.; Miller, P.; Walton, J. C. J. Org.
Chem. 2014, 79, 1386–1398.
13. Huang, Y.; Lin, Z.; Cao, R. Chem. Eur. J. 2011, 17, 12706–12712.
14. (a) Tang, D.-T. D.; Collins, K. D.; Glorius, F. J. Am. Chem. Soc.
2013, 135, 7450–7453; (b) Tang, D.-T. D.; Collins, K. D.; Ernst, J.
B.; Glorius, F. Angew. Chem. Int. Ed. 2014, 53, 1809–1813;
Collins, K. D.; Honeker, R.; Vásquez-Céspedes, S.; Tang, D.-T.
41. Xie, H.; Lin, F.; Lei, Q.; Fang, W. Organometallics 2013, 32,
6957–6868.