Impregnated palladium on magnetite, a new catalyst for the ligand-free cross-coupling Suzuki-Miyaura reaction

Article abstract of DOI:10.1016/j.tet.2011.05.072

A new catalyst for the cross-coupling Suzuki-Miyaura reaction is reported. The impregnated palladium on magnetite catalyst is very easy to prepare using the standard impregnation methodology. This catalyst avoids the use of any type of expensive and difficult handle organic ligand, showing excellent yields, under mild reaction conditions, for the classical formation of biaryl compounds. The catalyst is very easy to remove from the reaction medium, only by using a simple magnet, and it could be re-used up to three times with only a slightly decrease of the chemical yield.

Full text of DOI:10.1016/j.tet.2011.05.072

Tetrahedron 67 (2011) 5432e5436
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Impregnated palladium on magnetite, a new catalyst for the ligand-free
cross-coupling SuzukieMiyaura reaction
*
ꢀ
Rafael Cano, Diego J. Ramon , Miguel Yus
ꢀ
ꢀ
Instituto de Síntesis Organica (ISO), and Departamento de Química Organica, Facultad de Ciencias, Universidad de Alicante, Apdo. 99, E-03080 Alicante, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
A new catalyst for the cross-coupling SuzukieMiyaura reaction is reported. The impregnated palladium
on magnetite catalyst is very easy to prepare using the standard impregnation methodology. This catalyst
avoids the use of any type of expensive and difficult handle organic ligand, showing excellent yields,
under mild reaction conditions, for the classical formation of biaryl compounds. The catalyst is very easy
to remove from the reaction medium, only by using a simple magnet, and it could be re-used up to three
times with only a slightly decrease of the chemical yield.
Received 30 March 2011
Received in revised form 16 May 2011
Accepted 17 May 2011
Available online 25 May 2011
In memory of Prof. Dr. Borislav Bogdanovic
Ó 2011 Elsevier Ltd. All rights reserved.
Keywords:
Biaryl
Cross-coupling
Heterogeneous
Palladium
SuzukieMiyaura reaction
1. Introduction
from titanium,5 manganese,6 iron,7 cobalt,8 copper,9 ruthenium,10
rhodium,11 palladium,11,12 and platinum11 derivatives. However,
Over the past years transition-metal-catalyzed cross-coupling
reactions have matured to get an impressive level of generality and
complexity.1 They have been used in building bio-active molecules
as drugs and agrochemicals, in the developing of new generation of
ingeniously-designed organic materials with novel electronic,
optical or mechanical properties, likely to play a significant role in
the burgeoning area of nanotechnology.
Among the various transition-metal-catalyzed cross-coupling
reactions known today, the so-called SuzukieMiyaura reaction is
one of the most applied and valuable, owing to its exceptionally
broad functional group tolerance, as well as the use of readily
available, non-toxic, and air- and water-stable reagents.2 One of its
most important drawback is the presence of homogenous palla-
dium species on the final product, as well as the use of expensive,
difficult to prepare and handle ligands, such as phosphanes or
carbenes, and additives, such as organic ammonium salts. To avoid
the first drawback, different heterogeneous systems have been
proposed.2g,3 However, many of them use different grafted-ligands
to anchor the palladium atoms, maintaining the second drawback.
On the other hand, the old impregnation protocol has been used
very recently in the preparation of magnetite catalysts4 derived
their applications in organic chemistry have been quite limited. For
instance, the magnetically separable impregnated palladium on
magnetite system has catalyzed successfully the carbonylative
Sonogashira coupling reaction between aryliodides, ethynylarenes
and carbon monoxide.12a The presence of a chiral heterocyclic
carbene ligand permitted the enantioselective
a-arylation of
a
-substituted ketones using the above nanoparticles with enan-
tioselectivities up to 61%.12c The reduction of palladium with hy-
drogen permitted its use in the selective dehalogenation of organic
compounds from aqueous wastes.12b
Here, we report a simple, mild, and ligand-free protocol to
perform the SuzukieMiyaura reaction using the aforementioned
impregnated palladium on magnetite catalysts.13
2. Results and discussion
2.1. Arylation process
In order to optimize the reaction conditions we studied the
reaction between 1-iodo-4-methoxybenzene (1a) and phenyl-
boronic acid 2a to give the corresponding compound 3a, as depicted
inTable 1. Thereactionwas performed usingan excessofboronicacid
and equimolecular amounts of potassium carbonate. The formation
of product 3a was not detected after 5 days of reaction using DMF as
* Corresponding author. Tel.: þ34 965903986; fax: þ34 965903549; e-mail
ꢀ
address: djramon@ua.es (D.J. Ramon).
0040-4020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2011.05.072

R. Cano et al. / Tetrahedron 67 (2011) 5432e5436
5433
Table 1
bromobenzene (1b) and failed after 3 days for the case of the cor-
responding chlorinated and fluorinated reagent (1c,d).
a
Reaction condition optimization
Once the optimal reaction conditions were established, the
problem of recycling was faced. The catalyst recovered by a magnet
from the reaction described in the entry 12 of Table 1 was washed
with toluene and re-used under the same reaction conditions,
obtaining the expected product 3a in 82% yield. In the third re-use
the yield was 72%, indicating that there is a small decrease in the
activity of catalyst, probably due to the adsorption of Na2CO3 and
boronic salts on the surface of catalyst, which could be easily seen,
as well as the phenomena of leaching (0.9% of initial amount of
palladium on the magnetite surface was detected in the reaction
solution by ICP-MS analysis). In order to exclude that the hetero-
geneous catalyst was only an initial source for the homogeneous
palladium, a new reaction was carried out with the remaining so-
lution obtained after performing the standard reaction between
compounds 1a and 2a and isolation of magnetic catalyst. Phenyl-
boronic acid (2a), 1-iodonaphthalene, and Na2CO3 were added to
the above solution and the reaction was run for 4 days, with the
expected compound 3f being not detected.
X
B(OH)2
Pd(OH)2-Fe3O4
(1.2 mol%)
+
Base, solvent,
OMe
OMe
3a
2a
1a: X = I
1b: X = Br
1c: X = Cl
1d: X = F
Entry
X
Solvent
Base (mol %)
T (ꢀC)
t (h)
Yield (%)
1b
2
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
DMF
DMF
DMF
d
K2CO3 (120)
K2CO3 (120)
K2CO3 (120)
K2CO3 (120)
K2CO3 (120)
K2CO3 (120)
K2CO3 (120)
Na2CO3 (120)
KOH (120)
130
130
130
130
130
130
130
130
130
130
130
130
150
100
75
120
72
72
144
24
24
24
0.5
4
4
0
65
50
64
71
70
68
89
65
70
48
99
99
95
57
0
3c
4
5
6
7
8
PhMe
Dioxane
MeCN
PhMe
PhMe
PhMe
PhMe
PhMe
PhMe
PhMe
PhMe
PhMe
PhMe
PhMe
Other impregnated metals on magnetite were also tested to
evaluate their activity in comparison with palladium (entry 12 in
Table 1). The reaction with only the magnetite support gave the
expected product 3a in modest 20% yield after 3 h (Table 2, entry 1).
9
10
11
12
13
14
15
16
17d
18e
19
20
21
tBuOK (120)
Na2CO3 (50)
Na2CO3 (300)
Na2CO3 (300)
Na2CO3 (300)
Na2CO3 (300)
Na2CO3 (300)
Na2CO3 (300)
Na2CO3 (300)
Na2CO3 (300)
Na2CO3 (300)
Na2CO3 (300)
2
0.25
0.25
0.25
0.25
0.25
3
0.25
72
72
72
Table 2
Optimization of the reaction catalysta
25
130
130
130
130
130
5
98
50
0
Br
Cl
F
PhMe
PhMe
PhMe
B(OH)2
I
Catalyst
+
0
Na2CO3 (300 mol%),
PhMe, 130 ºC, 3 h
MeO
a
Reaction carried out using compounds 1 (1 mmol) and 2a (3 mmol) in 2 mL of
solvent, unless otherwise stated.
b
OMe
3a
Reaction performed without catalyst.
Compound 2a (1.2 mmol) was used.
Reaction carried out using 0.24 mol % of catalyst.
Reaction carried out using 2.4 mol % of catalyst.
c
1a
2a
d
e
Entry
Catalyst (mol %)
Yield (%)
1
2
3
4
5
Fe3O4 (22.0)
20
5
Co(OH)2/Fe3O4 (1.4)
Ni(OH)2/Fe3O4 (1.2)
Cu(OH)2/Fe3O4 (1.3)
Ru(OH)3/Fe3O4 (1.3)
65b
12
30
solvent at 130 ꢀC. However, the addition of the catalyst permitted to
obtain the compound 3a after only 3 days with a reasonable yield,
with the decrease of the boronic reagent having a slightly negative
impact on the yield (compare entries 1e3 in Table 1).
a
Reaction carried out using compounds 1a (1 mmol) and 2a (3 mmol) in 2 mL of
toluene.
b
After these initial experiments, the role of the solvent was
tested, finding practically no influence on the yield, except in the
absence of solvent (Table 1, entries 4e7). Once toluene was chosen
as possible solvent for the reaction, the nature of base was evalu-
ated. The reaction using sodium carbonate gave the expected
compound 3a in only 30 min, meanwhile stronger bases, such as
potassium hydroxide or tert-butoxide gave worse results (entries
9 and 10 in Table 1). However, the amount of base is a critic pa-
rameter since its increase up to 300 mol % (amount of boronic acid),
permitted to obtain the expected compound in practically quanti-
tative yield in only 15 min, with its decrease reducing the yield
(compare entries 8, 11, and 12 in Table 1). The temperature of the
reaction is also an important parameter in order to obtain com-
pound 3a, with temperatures higher than 100 ꢀC producing prac-
tically quantitative yields (Table 1, entries 12e16), with the reaction
failing at room temperature.
Reaction performed during 15 min.
Other impregnated catalysts, such as cobalt, copper or ruthe-
nium derivatives did not improve the obtained results with the
support. However, the impregnated nickel on magnetite showed
a higher activity compared to the related catalysts (compare entries
2e5 in Table 2), but lower than the aforementioned palladium
derivative.
Once the best conditions were found for this SuzukieMiyaura
process (entry 12 in Table 1), the same protocol was applied to
other substrates in order to study the scope of the reaction (Table
3). The reaction gave excellent results for electron-rich four-
substituted iodobenzenes independently of the electronic nature of
boronic acid, with the yield being lower only in the case of thienyl
derivative (compare entries 1e5 in Table 3).
The results were excellent in the case of using unsubstituted
aromatic iodides, independently of the aromatic size (compare
entries 6e8 in Table 3), with the reaction being a little slower for
electron-withdrawing substituted aromatic boronic acids. The
reaction could be performed with similar trends in the case of using
electron-withdrawing substituted aromatic iodides (Table 3, en-
tries 13e13), even in the case of using an iodopyridine derivative
(Table 3, entry 14).
Whereas a 5% of compound 3a was detected after 3 h when the
reaction was performed using only 0.24 mol % of the heterogeneous
palladium catalyst, the increase of this amount up to 2.4 mol % did
not have any significant positive impact on the previous results
(compare entries 12, 17, and 18 in Table 1).
The nature of the halogen atom in reagent 1 was also tested
(Table 1, entries 19e21). The reaction gave a worse result using

5434
R. Cano et al. / Tetrahedron 67 (2011) 5432e5436
Table 3
an AUTOSORB-6 (Quantachrome), using N2. Melting points were
Arylation of aromatic compoundsa
obtained with a Reichert Thermovar apparatus. NMR spectra were
recorded on a Bruker AC-300 (300 MHz for 1H, 75 MHz for 13C, and
282 MHz for 19F) using CDCl3 as a solvent and TMS as internal
standard for 1H and 13C and CFCl3 for 19F; chemical shifts are given
Pd(OH)2-Fe3O4
(1.2 mol%)
Ar2
Ar1
Ar1
Ar2 B(OH)2
+
I
Na2CO3 (300 mol%),
PhMe, 130 ºC, 1 h
in
d (parts per million) and coupling constants (J) in Hertz. FT-IR
3
1
2
spectra were obtained on a Nicolet Impact 400D spectrophotom-
eter. Mass spectra (EI) were obtained at 70 eV on a Himazdu
QP-5000 spectrometer, giving fragment ions in m/z with relative
intensities (%) in parentheses. Thin layer chromatography (TLC) was
carried out on Schleicher and 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$4H2O, 60 mL of concentrated H2SO4, and 940 mL H2O].
The chromatographic analyses (GLC) were determined with an
instrument equipped with a flame ionization detector and a 12 m
capillary column (0.2 mm diam, 0.33 mm film thickness, OV-1
stationary phase), using nitrogen (2 mL/min) as a carrier gas, Tin-
jector ¼ 275 ꢀC, Tdetector ¼ 300 ꢀC, Tcolumn ¼ 60 ꢀC (3 min) and
60e270 ꢀC (15 ꢀC/min), P ¼ 40 kPa. Column chromatography was
performed using silica gel 60 of 35e70 mesh. All reagents were
commercially available (Acros, Aldrich, Fluorochem) and were used
as received.
Entry
Ar1
A2
Ph
Biaryl
Yield (%)
1
2
3
4
5
6
7
8
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
4-MeC6H4
Ph
3a
99
90
4-MeC6H4
3b
3c
3d
3b
3a
3e
3f
3g
3h
3i
4-FC6H4
Thien-3-yl
4-MeOC6H4
4-MeOC6H4
4-FC6H4
Ph
4-MeOC6H4
Ph
4-FC6H4
Ph
99b
54c
92c
89
Ph
97b
99
1-Naphthyl
4-MeCOC6H4
4-MeCOC6H4
4-MeCOC6H4
C6F5
9
99
99
10
11
12
13
14
80b
87c
23c
64b
3j
3k
3l
C6F5
Pyridin-2-yl
Thien-3-yl
Ph
a
Reaction carried out using compounds 1 (1 mmol) and 2 (3 mmol) in 2 mL of
toluene.
b
c
Reaction performed during 24 h.
Reaction performed during 48 h.
4.2. Impregnated palladium on magnetite catalyst
preparation
Other aromatic nucleophilic partners different from boronic
acids 2 were also tested giving very modest results after 4 days of
reaction time for the preparation of compound 3a, including po-
tassium phenyltrifluoroborate14 (10%), sodium tetraphenylborate15
(19%), tetraphenyltin16 (0%), and triethoxy(phenyl)silane17 (0%).
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 (3ꢁ10 mL).
The solid was dried at 100 ꢀC during 24 h in a standard glassware
oven, obtaining the expected catalyst: incorporation of palladium
of 2.6% according to XRF; by XPS the palladium18 on the surface was
determined as 24.8%; the BET area surface was 13.6 m2/g.
Ph
Ph
I
-
)
F
2
(
Pd
H
O
.
e3O4
)
Ph
mo
(
1 2
l
%
+
+
a
N
2CO3
(300 mol
PhMe, 130 º 24 h
% ,
)
B
(
H
O
)
2
,
C
M
O
e
e
M
O
e
M
5 (71
O
6 (19
)
a
%
1
4
)
%
4.3. General procedure for typical procedure for the
SuzukieMiyaura reaction
Scheme 1. Alkenylation process.
To a stirred solution of aromatic iodide (1, 1 mmol) in toluene
(2 mL) were added Pd(OH)2/Fe3O4 (50 mg, 1.2 mol % of Pd), Na2CO3
(3 mmol, 318 mg), and the corresponding boronic acid (2 or 4,
3 mmol). The resulting mixture was stirred at 130 ꢀC for 1 h. The
catalyst was removed by a magnet and the resulting mixture was
quenched with water and extracted with EtOAc. The organic phases
were dried over MgSO4, followed by evaporation under reduced
pressure to remove the solvent. The corresponding products 3 or 5
were usually purified by chromatography on silica gel (hexane/
ethyl acetate).
2.2. Alkenylation process
Finally, we applied the same protocol to the alkenyl boronic
reagent 4 (Scheme 1), with the reaction giving a mixture of prod-
ucts 5 and 6.
3. Conclusion
In conclusion, we have demonstrated that the impregnated
palladium on magnetite is a good catalyst for the typical Suzu-
kieMiyaura reaction in absence of extra organic ligands and addi-
tives, with the elimination of catalyst from the reaction medium
being very easy using a magnet. The reaction could be performed
with a broad range of aromatic iodinated substrates, keeping the
high level of the results.
4.3.1. 4-Methoxybiphenyl (3a)17. Mp 91e93 ꢀC (ethyl acetate/hex-
ane). Rf 0.53 (hexane/ethyl acetate: 4/1). tr 13.2; IR (KBr)
1248, 1046 cmꢂ1. 1H NMR (300 MHz, CDCl3):
3.80 (3H, s, OCH3),
6.95e7.00, 7.25e7.30, 7.35e7.45, 7.50e7.55 (2, 1, 2, and 4H, re-
spectively, 4m, AreH). 13C NMR (75 MHz, CDCl3)
55.2, 114.1 (2C),
n 1607,1524,
d
d
126.6,126.7 (2C),128.1 (2C),128.7 (2C),133.7,140.8,159.1. GC/MS m/z
185 (Mþþ1,15%),184 (Mþ, 100), 169 (46), 141 (42),139 (11),115 (28).
4. Experimental section
4.1. General information
4.3.2. 4-Methoxy-40-methylbiphenyl (3b)19. Mp 115e118 ꢀC (ethyl
acetate/hexane). Rf 0.63 (hexane/ethyl acetate: 4/1). tr 14; IR (KBr)
n
The ICP-MS analysis was performed on a Thermo Elemental
VGPQ-Excell spectrometer and the XPS analyses were carried out
on a VG-Microtech Mutilab. The BET isotherms were carried out on
1600, 1502, 1248, 1035 cmꢂ1. 1H NMR (300 MHz, CDCl3):
d
2.35 (3H,
s, CCH3), 3.77 (3H, s, OCH3), 6.92 (2H, d, J¼9.2 Hz, 2ꢁ OCCH), 7.18
(2H, d, J¼8 Hz, 2ꢁ CH3CCH), 7.42 (2H, d, J¼8 Hz, 2ꢁ CH3CHCH), 7.48

R. Cano et al. / Tetrahedron 67 (2011) 5432e5436
5435
(2H, d, J¼8.86 Hz, 2ꢁ OCCHCH). 13C NMR (75 MHz, CDCl3)
d
21, 55.2,
JCF¼21.5 Hz, 2C), 126.9 (2C), 128.8 (d, JCF¼8.2 Hz, 2C), 128.9 (2C),
135.6, 135.8 (d, JCF¼3.2 Hz), 144.6, 162.8 (d, JCF¼248.1 Hz), 197.9. GC/
MS m/z 214 (Mþ, 57), 200 (17), 199 (100), 171 (45), 170 (75), 169 (12).
114.1 (2C), 126.5 (2C), 127.9 (2C), 129.4 (2C), 133.6, 136.2, 137.9,
158.9. GC/MS m/z 199 (Mþþ1,16%),198 (Mþ,100),183 (53),155 (27),
153 (10), 152 (10).
4.3.10. 2,3,4,5,6-Pentafluoro-1,10-biphenyl (3j)23. Mp 111e113 ꢀC
(ethyl acetate/hexane). Rf 0.77 (hexane/ethyl acetate: 4/1). tr 10.9; IR
4.3.3. 4-Fluoro-40-methoxybiphenyl (3c)15. Mp 92e96 ꢀC (ethyl ac-
etate/hexane). Rf 0.63 (hexane/ethyl acetate: 4/1). tr 13.1; IR (KBr)
1604,1230,1039, 832 cmꢂ1. 1H NMR (300 MHz, CDCl3):
3.81 (3H, s,
OCH3), 6.90e6.95, 7.05e7.10, 7.40e7.50 (2, 2, and 4H, respectively,
3m, AreH). 13C NMR (75 MHz, CDCl3)
55.2, 114.2 (2C), 115.5 (d,
n
(KBr) n d 7.40e7.45,
1650,1582, 980 cmꢂ1.1H NMR (300 MHz, CDCl3):
d
7.45e7.50 (2 and 3H, respectively, 2m, AreH). 13C NMR (75 MHz,
CDCl3)
d
115.9 (td, 2JCF¼17.6 Hz, 3JCF¼3.8 Hz),126.4,128.7 (2C),129.3,
d
130.1 (2C), 137.8 (2C, dm, JCF¼252.5 Hz), 140.4 (dm, JCF¼253.7 Hz),
JCF¼20.9 Hz), 128 (2C), 128.1 (d, JCF¼7.4 Hz), 132.7, 136.9, 159.1, 162
(d, JCF¼245.1 Hz). GC/MS m/z 203 (Mþþ1, 15%), 202 (Mþ, 100), 187
(52), 159 (48), 133 (26).
144.1 (2C, dm, JCF¼248 Hz). 19F NMR (282 MHz, CDCl3)
ꢂ143.3 (2F,
d
dd,1J¼23 Hz, 2J¼8.2 Hz), ꢂ155.7 (t, J¼21.2 Hz), ꢂ162.3 (2F, m). GC/MS
m/z 244 (Mþ, 100), 225 (16), 224 (29), 205 (10).
4.3.4. 3-(4-Methoxyphenyl)thiophene (3d)20. Mp 126e128 ꢀC (ethyl
4.3.11. 3-(Perfluorophenyl)thiophene (3k)23. Rf 0.9 (hexane/ethyl
acetate/hexane). Rf 0.87 (hexane/ethyl acetate: 4/1). tr 15; IR (KBr)
n
acetate: 4/1). tr 11.3; IR (film)
(300 MHz, CDCl3): 7.35e7.40, 7.45e7.50, 7.60e7.65 (1H each one,
n .
1538, 1516, 990 cmꢂ1 1H NMR
3097,1603,1538,1249,1038 cmꢂ1. 1H NMR (300 MHz, CDCl3):
d
3.80
d
2
(3H, s, OCH3), 6.91 (2H, d, J¼8.7 Hz, 2ꢁ OCCH), 7.30e7.35 (3H, m,
3m, AreH). 13C NMR (75 MHz, CDCl3)
d
111.1 (td, JCF¼16.2 Hz,
C4H3S), 7.51 (2H, d, J¼8.6 Hz, 2ꢁ OCCHCH). 13C NMR (75 MHz,
3JCF¼3.6 Hz), 125.5, 125.8, 127.1 (t, 4J¼4.3 Hz), 128.1 (t, 4J¼3.5 Hz),
137.9 (2C, dm, JCF¼251.4 Hz), 139.9 (dm, JCF¼253.5 Hz), 144.2 (2C,
CDCl3)
d 55.2, 114.1 (2C), 118.9, 126, 126.2, 127.5 (2C), 128.6, 141.9,
158.8. GC/MS m/z 191 (Mþþ1, 12%), 190 (Mþ, 100), 176 (10), 175 (83),
dm, JCF¼248 Hz). 19F NMR (282 MHz, CDCl3)
d
ꢂ142.5 (2F, dd,
147 (44).
1J¼23.2 Hz, 2J¼7 Hz), ꢂ156.8 (t, J¼21.2 Hz), ꢂ162.8 (2F, m). GC/MS
m/z 251 (Mþþ1, 11%), 250 (Mþ, 100), 205 (23).
4.3.5. 4-Fluoro-1,10-biphenyl (3e)15. Mp 73e76 ꢀC (ethyl acetate/
hexane). Rf 0.87 (hexane/ethyl acetate: 4/1). tr 10.9; IR (KBr)
4.3.12. 3-Phenylpyridine (3l)24. Rf 0.4 (hexane/ethyl acetate: 4/1). tr
n
1589, 1524, 760 cmꢂ1
.
1H NMR (300 MHz, CDCl3):
d
7.03e7.09,
7.29e7.31, 7.35e7.4, 7.45e7.5 (2, 1, 2, and 4H, respectively, 4m,
AreH). 13C NMR (75 MHz, CDCl3)
11.6; IR (film)
7.35e7.50, 7.55e7.60, 7.90e7.95, 8.60e8.65, 8.85e8.90 (4, 2, 1, 1,
and 1H, respectively, 5m, AreH). 13C NMR (75 MHz, CDCl3)
123.8,
n .
1600, 1574 cmꢂ1 1H NMR (300 MHz, CDCl3):
d
d
115.5 (2C, d, JCF¼21.2 Hz), 126.9
d
(2C), 127.2, 128.6 (2C, d, JCF¼8.1 Hz), 128.8 (2C), 137.2 (d,
JCF¼3.3 Hz), 140.1, 162.4 (d, JCF¼246.2 Hz). GC/MS m/z 173 (Mþþ1,
28%), 172 (Mþ, 100), 171 (85), 170 (60), 169 (11), 146 (13), 133 (10),
85 (11).
127.1 (2C), 128.2, 129.1 (2C), 135, 136.9, 137.3, 147.4, 147.5. GC/MS m/
z 156 (Mþþ1, 12%), 155 (Mþ, 100), 154 (51), 128 (10), 127 (13), 102
(10), 85 (11).
4.3.13. (E)-1-Methoxy-4-styrylbenzene (5)25. Mp 134e138 ꢀC (ethyl
acetate/hexane). Rf 0.53 (hexane/ethyl acetate: 4/1). tr 15.6; IR
4.3.6. 1-Phenylnaphthalene (3f)17. Rf 0.9 (hexane/ethyl acetate: 4/1).
tr 14.7; IR (film)
(300 MHz, CDCl3):
respectively, 3m, AreH).13C NMR (75 MHz, CDCl3)
n
1593, 1582, 803, 774, 759, 705 cmꢂ1
.
1H NMR
(film)
3.80 (3H, s, OCH3), 6.85e6.90, 6.95e7.10, 7.20e7.25, 7.30e7.40,
7.45e7.50 (2, 2, 1, 2, and 4H, respectively, 5m, AreH and CH]CH).
13C NMR (75 MHz, CDCl3)
55.3, 114.1 (2C), 126.2 (2C), 126.6, 127.2,
n .
1603, 1513, 1292, 1027 cmꢂ1 1H NMR (300 MHz, CDCl3):
d
7.30e7.45, 7.75e7.80, 7.85e7.90 (9, 2, and 1H,
125.3,125.7,126
d
d
(2C), 126.9, 127.1, 127.6, 128.2 (3C), 130 (2C), 131.6, 133.4, 140.2, 140.7.
GC/MS m/z 205 (Mþþ1, 16%), 204 (Mþ, 100), 203 (99), 202 (61), 201
(12), 200 (12), 101 (28).
d
127.7 (2C), 128.2, 128.6 (2C), 131.1, 137.6, 159.3. GC/MS m/z 211
(Mþþ1,17%), 210 (Mþ,100), 209 (15),195 (17),167 (21),166 (11),165
(33), 152 (20).
4.3.7. 1-[40-Methoxy-(1,10-biphenyl)-4-yl]ethanone
153e154 ꢀC (ethyl acetate/hexane). Rf 0.37 (hexane/ethyl acetate:
4/1). tr 16.4; IR (KBr)
1669, 1600, 1524, 1288, 1035 cmꢂ1. 1H NMR
(300 MHz, CDCl3): 2.60 (3H, s, CCH3), 3.84 (3H, s, OCH3), 6.98 (2H,
(3g)21. Mp
4.3.14. 1-Methoxy-4-(1-phenylvinyl)benzene (6)26. tr 14.1. 1H NMR
n
(300 MHz, CDCl3):
d
3.81 (3H, s, OCH3), 5.34 (1H, d, J¼1.2 Hz), 5.39
d
(1H, d, J¼1.2 Hz), 6.85e6.90, 7.25e7.40 (2 and 7H, respectively, 2m,
ArH). GC/MS m/z 211 (Mþþ1, 17%), 210 (Mþ, 100), 209 (12), 195 (53),
179 (12), 178 (11), 167 (16), 166 (12), 165 (36), 152 (24).
d, J¼9 Hz, 2ꢁ OCCH), 7.56 (2H, d, J¼8.7 Hz, 2ꢁ OCCHCH), 7.62 (2H,
d, J¼8.3 Hz, 2ꢁ OCCCHCH), 7.99 (2H, d, J¼8.4 Hz, 2ꢁ OCCCH). 13C
NMR (75 MHz, CDCl3) d 26.5, 55.3, 114.3 (2C), 126.5 (2C), 128.3 (2C),
128.9 (2C), 132.1, 135.1, 145.2, 159.8, 197.6. GC/MS m/z 227 (Mþþ1,
13%), 226 (Mþ, 83), 212 (20), 211 (100), 183 (14), 168 (28), 152 (18),
140 (27), 139 (46).
Acknowledgements
This work was financially supported by the Spanish Ministerio
de Ciencia y Tecnología (Proyects CTQ2007-65218/BQU and Con-
solider Ingenio 2010 CSD2007-00006) and Generalitat Valenciana
(G.V. PROMETEO/2009/039 and FEDER). R.C. thanks to G.V. for
a fellowship through the PROMETEO program.
4.3.8. 1-(Biphenyl-4-yl)ethanone (3h)17. Mp 124e127 ꢀC (ethyl ac-
etate/hexane). Rf 0.3 (hexane/ethyl acetate: 4/1). tr 14.4; IR (KBr)
n
1676, 1603, 1556 cmꢂ1 1H NMR (300 MHz, CDCl3):
.
d
2.64 (3H, s,
CH3), 7.40e7.45, 7.45e7.50, 7.60e7.65, 7.65e7.70, 8.002e8.05 (1, 2,
2, 2, and 2H, respectively, 5m, AreH). 13C NMR (75 MHz, CDCl3)
Supplementary data
d
26.6, 127.2 (2C), 127.3 (2C), 128.2, 128.9 (2C), 128.9 (2C), 135.8,
139.9, 145.8, 197.7. GC/MS m/z 196 (Mþ, 51), 182 (14), 181 (100), 153
Supplementary data associated with this article can be found in
the online version at doi:10.1016/j.tet.2011.05.072.
(34), 152 (52), 151 (14), 76 (11).
4.3.9. 1-[40-Fluoro-(1,10-biphenyl)-4-yl]ethanone (3i)22. Mp 91e94 ꢀC
(ethyl acetate/hexane). Rf 0.5 (hexane/ethyl acetate: 4/1). tr 14.4; IR
References and notes
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