Pd black in water as an efficient catalyst of the Suzuki reaction

Full text of DOI:10.1023/A:1026097813946

1
882
Russian Chemical Bulletin, International Edition, Vol. 52, No. 8, pp. 1882—1883, August, 2003
Letters to the Editor
Pd black in water as an efficient catalyst of the Suzuki reaction
ꢀ
A. G. Kuznetsov, D. N. Korolev, and N. A. Bumagin
Department of Chemistry, M. V. Lomonosov Moscow State University,
Leninskie Gory, 119992 Moscow, Russian Federation.
Fax: +7 (095) 939 0126. Eꢀmail: bumagin@org.chem.msu.su
Crossꢀcoupling of organoboron compounds with orꢀ
Scheme 1
ganic halides (the Suzuki reaction) is widely used in modꢀ
ern organic synthesis as a convenient method for the forꢀ
1
mation of new carbon—carbon bonds with almost comꢀ
plete retention of functional groups in the reactants. The
use of nonrecoverable Pd catalysts is a disadvantage of the
2
presently known versions of the Suzuki reaction. Thereꢀ
fore, the development of catalytic systems that could be
used multiply is of great practical interest. Evidently, Pd
black, being accessible and easily recoverable, is most
3
attractive for this purpose. We have previously shown
that Pd black (1 mol.%) is an efficient catalyst in the
Suzuki reaction at room temperature with waterꢀsoluble
aryl iodides and water as a solvent. Crossꢀcoupling of
arylboronic acids with aryl iodides in methanol occurs on
boiling of the reaction mixture in the presence of 50 mol.%
X = 3ꢀNH , 4ꢀMeO, 2,4,6ꢀMe3
2
i. 50 mol.% of Pd black, Na CO , H O, 100 °C, 6—8 h
2
3
2
ents, the amount of the catalyst and duration of the reacꢀ
tion can be decreased (Scheme 2).
This catalytic system is so efficient that waterꢀsoluble
aryl halides react in 5—10 min even in the presence of
4
of Pd black. Under these conditions, aryl bromides do
not react.
1
mol.% of the catalyst (Scheme 3).
In the present work, we showed that Pd black is an
efficient and easily recoverable catalyst in the crossꢀ
coupling of pꢀtolylboronic acid with pꢀbromoanisole,
mꢀbromoaniline, and bromomesitylene, i.e., the most inꢀ
ert substrates in the Suzuki reaction (Scheme 1).
After completion of the reaction, Pd black is separated
by decantation and can be used repeatedly. In the case of
aryl bromides containing electronꢀwithdrawing substituꢀ
Pd black. A 0.1 М solution of PdCl (100 mL) and HCO H
2
2
(
99%, 5 mL) were refluxed for 30 min. Pd black was separated
by decantation, washed with water (5×10 mL), and dried for 2 h
at 120 °C. The yield was 1.02 g (96%).
4
ꢀMethoxyꢀ4´ꢀmethylbiphenyl. A mixture of pꢀbromoanisole
0.187 g, 1 mmol), pꢀtolylboronic acid (0.15 g, 1.1 mmol),
Na CO (0.212 g, 2 mmol), Bu NBr (0.003 g, 0.01 mmol), and
(
2
3
4
Pd black (0.053 g, 0.5 mmol) in water (3 mL) was refluxed in a
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1783—1784, August, 2003.
066ꢀ5285/03/5208ꢀ1882 $25.00 © 2003 Plenum Publishing Corporation
1

Pd blackꢀcatalyzed Suzuki reaction
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 8, August, 2003
1883
Scheme 2
ated Pd black (0.052 g, 98%) was repeatedly used in crossꢀ
coupling reactions. The reaction product was extracted with
ether. The combined ethereal extracts were dried with Na SO
2
4
and passed through a pad of silica gel. After removal of
ether, 4ꢀmethoxyꢀ4´ꢀmethylbiphenyl was obtained in 75% yield
1
(
0.148 g), m.p. 110 °C (cf. Ref. 5: 109 °C). H NMR (DMSOꢀd ,
6
3
(
8
00 MHz), δ: 2.33 (s, 3 H, MеAr); 3.79 (s, 3 H, MeOAr); 6.98
d, 2 H, MeOCCH, J = 8.6 Hz); 7.24 (d, 2 H, MeAr, J =
.0 Hz); 7.50 (d, 2 H, MeAr, J = 8.04 Hz); 7.57 (d, 2 H,
MeOCCHCH, J = 8.0 Hz).
ꢀ(4ꢀAcetylphenyl)benzoic acid. The reaction of pꢀbromoꢀ
3
acetophenone (0.199 g, 1 mmol) with mꢀcarboxyphenylboronic
acid (0.183 g, 1.1 mmol) in the presence of Pd black (0.027 g,
0
0
.25 mmol), Na CO (0.318 g, 3 mmol), and Bu NBr (0.003 g,
2 3 4
.01 mmol) was carried out similarly for 2.5 h. This Pd black
(
0.027 g, 0.25 mmol) has been used in the previous experiment
and in reactions of pꢀtolylboronic acid with mꢀbromoaniline
i. 25 mol.% of Pd black, Na CO , H O, 100 °C, 2.5 h
and bromomesitylene. After Pd black was separated (0.025 g,
2
3
2
9
2%) and the reaction mixture was acidified with НСl, 3ꢀ(4ꢀaceꢀ
tylphenyl)benzoic acid was obtained (0.405 g, 85%), m.p. 194 °C.
1
Scheme 3
H NMR (DMSOꢀd , 300 MHz), δ: 2.62 (s, 3 H, MeCO); 7.64
6
(
8
t, 1 H, С(5)H, J = 7.7 Hz); 7.89 (d, 2 H, C(2´)H, C(6´)H, J =
.4 Hz), 7.98—8.02 (m, 2 H, C(4)H, C(6)H); 8.09 (d, 2 H,
C(3´)H, J = 8.3 Hz); 8.24 (br.s, 1 H, C(2)H).
References
1
2
3
4
5
. A. Suzuki, J. Organomet. Chem., 1999, 576, 147; N. Miyaura
and A. Suzuki, Chem. Rev., 1995, 95, 2457.
. S. Kotha, K. Lahiri, and D. Kashinath, Tetrahedron, 2002,
5
8, 9633.
. V. V. Bykov and N. A. Bumagin, Izv. Akad. Nauk, Ser. Khim.,
997, 1399 [Russ. Chem. Bull., 1997, 46, 1344 (Engl. Transl.)].
1
. W. Kabalka, V. Namboodiri, and L. Wang, Chem. Commun.,
2001, 775.
. N. Kruber, Ber., 1932, 65, 1382.
X = mꢀBr, pꢀl
i. 1 mol.% of Pd black, Na CO , H O, 100 °C, 5—10 min
2
3
2
Schlenk apparatus with vigorous stirring for 8 h under argon.
After cooling, Pd black was separated by decantation, washed
with water (3×5 mL), and dried for 2 h at 120 °C. The regenerꢀ
Received April 22, 2003;
in revised form July 21, 2003