2848
D.L. Martins et al. / Journal of Organometallic Chemistry 696 (2011) 2845e2849
4
dried with anhydrous MgSO , filtered and the solvent removed
under reduced pressure.
4.2. General procedure for the reactions under conventional heating
Scheme 2. Suzuki reaction between aroyl chlorides and boronic acids.
A sealed tube, charged with the reaction mixture, was immersed
ꢀ
in a pre-heated oil bath at 120 C for 7 min, after which this mixture
Scheme 3. Reaction pathways to biphenyls in the Suzuki reactions.
found. It can be envisaged that the electron-deficient boronic acids
can act also as electrophiles in the couplings and, then give rise to
houmocoupling products.
was treated the same manner described for the representative
procedure under MW heating and analyzed by GC/MS.
Benzophenone: GCeMS: 182 m/z, 105 m/z, 77 m/z, 51 m/z.
4
-Nitrobenzophenone: GCeMS: 227 m/z; 181 m/z; 150 m/z;
13
3
. Conclusion
105 m/z; 77 m/z. C NMR (CDCl
3
, 50 MHz) 193.5; 148.9; 141.7;
1
35.1; 134.4; 132.3; 129.5; 128.9; 127.5; 126.7; 122.3.
4-Fluorobenzophenone: solid. C NMR (CDCl , 50 MHz) 195.4;
3
13
In summary, supported palladium catalysts, as well as Pd
2
dba
3
,
has been found to be effective catalysts for the coupling of aryl-
boronic acids with aroyl chlorides. Aromatic ketones were obtained
in high yields (79e99%) without the addition of phosphine ligands
in 5 min under microwave irradiation.
168.0 and 163.0; 137.6; 133.92 and 133.85; 132.9; 132.7; 130.0;
115.8 and 115.3 ppm. GCeMS: 200 m/z, 123 m/z, 105 m/z, 95 m/z,
69 m/z.
3-Chlorobenzophenone: solid. GCeMS: 200 m/z; 181 m/z; 139 m/z;
1
11 m/z; 105 m/z; 77 m/z; 63 m/z; 51 m/z.
Naphthalene-2-yl(phenyl)methanone - GCeMS: 232 m/z; 155 m/z;
27 m/z; 105 m/z; 101 m/z; 77 m/z; 51 m/z.
-Chlorobenzophenone: GCeMS: 200 m/z; 181 m/z; 139 m/z;
4
. Experimental
1
3
Reactions were carried out with a single mode cavity Discover
1
11 m/z; 105 m/z; 77 m/z; 63 m/z; 51 m/z.
4
Microwave synthesizer (CEM Corporation, NC, USA) producing
continuous irradiation at 2455 MHz and infrared temperature
control system. Microwave experiments were carried out in sealed
tubes equipped with an efficient magnetic stirring (which avoid
problems of non-homogeneity in temperature). The analyses by
GCeMS were performed on a Shimadzu GC-MS-QP2010Plus. The
separation of the compounds was achieved on RTꢁ5MS
-Hydroxybenzophenone: GCeMS: 198 m/z; 105 m/z; 93 m/z;
7 m/z; 51 m/z.
-Thienylphenylketone: 188 m/z; 111 m/z; 105 m/z; 83 m/z; 77 m/z.
C NMR (CDCl , 50 MHz) 188.3; 143.7; 138.2; 135.0; 134.3; 132.4;
29.7; 129.0; 128.5 ppm.
Biphenyl: GCeMS: 154 m/z; 153 m/z; 128 m/z; 102 m/z; 76 m/z;
1 m/z.
-Nitrobiphenyl: GCeMS: 199 m/z; 169 m/z; 152 m/z; 76 m/z;
7
2
13
3
1
5
(
30 m ꢁ 0.25 mm ꢁ 0.25
mm). Helium was used as a carrier gas and
4
the injection split ratio was 1:20. Separation was achieved using the
ꢀ
63 m/z; 51 m/z; 46 m/z. 2-Phenylnaphthalene: GCeMS: 204 m/z;
126 m/z; 101 m/z; 89 m/z; 76 m/z; 63 m/z.
following temperature program: 20 C/min from 100 (hold
ꢀ
time ¼ 2 min) to 260 C (hold time ¼ 2 min). Injector and detector
ꢀ
ꢀ
3-Chlorobiphenyl: GCeMS: 188 m/z; 152 m/z; 126 m/z; 126 m/z;
temperatures were 260 C and ion source temperature was 200 C.
Conversions were based on the consumption of the aroyl chloride
7
6 m/z; 63 m/z; 51 m/z.
,4’-Difluorobiphenyl: GCeMS: 190 m/z; 172 m/z; 164 m/z;
51 m/z; 120 m/z; 95 m/z.
13
4
by normalization of areas. C NMR spectra were recorded on
13
1
a Brucker AMX-200 spectrometer operating at 50 MHz ( C) in
CDCl with TMS as an internal standard.
3
Acknowledgements
4
.1. General procedure for the microwave-assisted reactions
Financial support from CNPq. The authors thanks professor Dr.
Heiddy Marquez.
In a typical experiment, a tube equipped with a magnetic stirrer
was charged with 1.0 mmol of base, 0.5 mmol of boronic acid,
.005 mmol of Pd dba or 1.0% weight of the supported palladium
0
2
3
References
catalyst, 1.0 mL of the solvent and 0.5 mmol of the aroyl chloride.
This tube was sealed and the content was subjected to focused
microwave irradiation at 250 W for 7.0 min with 120 C as the
[
1] B.M. Baughman, E. Stennett, R.E. Lipner, A.C. Rudawski, S.J. Schidtke, J. Phys.
Chem. A. 113 (2009) 8011e8019.
ꢀ
[2] A.L. Ong, A.H. Kamaruddin, A.S. Bhatia, Process Biochem. 40 (2005)
general final temperature. Then the reaction mixture was cooled to
room temperature and diluted with 8.0 mL of ethyl ether, filtered
and the residue was washed with two portions of ethyl ether
3526e3535.
[
[
3] G. Ekambaram, P. Rajendran, V. Magesh, P. Sakthisekaran, Nutr. Res. 8 (2008)
06e112.
4] E. Fillion, D. Fishlock, A. Wilsily, J.M. Goll, J. Org. Chem. 70 (2005) 1316e1327.
1
(
8.0 mL). This solution was analyzed by GC/MS.
For the isolation of the ketones, after cooling to room temper-
[5] J. Ross, J. Xiao, Green Chem. 4 (2002) 129e133.
[
[
[
6] R.K. Dieter, Tetrahedron 55 (1999) 4177e4236.
7] S. Baba, E. Negishi, J. Am. Chem. Soc. 98 (1976) 6729e6731.
8] D. Milstein, J.K. Stille, J. Am. Chem. Soc. 101 (1979) 4992e4998.
ature, the reaction mixture was diluted with ethyl acetate and
washed with aqueous NaOH 10% and water, filtered over celite,
[9] N. Miyaura, T. Yanagi, A. Suzuki, Synth. Comm. 11 (1981) 513e519.