A. Robichaud, A. Nait Ajjou / Tetrahedron Letters 47 (2006) 3633–3636
3635
a
Table 2. DRA of various aldehydes with different amines catalyzed by Pd(PhCN)
2
Cl
2
/BQC
O
R1
R R NH (2)
1
2
R
N
3
+
R
OH
R
H
R2
4
1
Entry
Aldehyde (1)
Amine (2)
PhCH NH
CH (CH
PhCH CH
(CH CHNH
PhCH NH
Conversion (%)
Alkylated amine (3) yield (%)
Alcohol (4) yield (%)
1
2
3
4
5
6
PhCHO
PhCHO
PhCHO
PhCHO
2
2
100
100
100
100
100
100
100
88
100
100
100
100
95
97
99
90
93
99
90
44
93
99
0
5
3
0
10
7
0
0
44
0
0
100
100
3
2
)
5
NH
NH
2
2
2
2
3
)
2
2
p-CH
p-CH
3
O–C
O–C
6
H
H
4
CHO
CHO
2
2
3
6
4
CH
CH
CH
3
3
3
(CH
(CH
(CH
2
)
2
)
2
)
5
5
5
NH
NH
NH
2
b
7
CH
PhCOCH
CH (CH
3
(CH
2
)
10CHO
2
2
8
9
3
3
2
)10CHO
(CH
(CH
3
(CH
(CH
2
)
)
5
)
)
2
NH
NH
10
11
12
PhCHO
PhCHO
PhCHO
3
2
5
2
iPr
2
NH
(PhCH
2
)
2
NH
0
a
Reaction conditions: aldehyde (2.5 mmol), amine (2.5 mmol), Pd(PhCN)
Tertiary amine was obtained with 8% yield.
2 2 2
Cl (0.025 mmol), BQC (0.15 mmol), water (10 mL), H (200 psi), 100 °C.
b
reductive amination of aldehydes with primary and sec-
ondary amines. The reaction is performed under mole-
cular hydrogen pressure using Pd(PhCN) Cl /BQC. The
catalytic system is stable and can be recycled and reused
three times without loss of activity and selectivity.
Tetrahedron 2005, 61, 5725; (c) Miriyala, B.; Bhatta-
charyya, S.; Williamson, J. S. Tetrahedron 2004, 60, 1463;
(
d) Apodaca, R.; Xiao, W. Org. Lett. 2001, 3, 1745.
2
2
1
1
0. Moormann, A. E. Synth. Commun. 1993, 23, 789.
1. (a) Ryschkewitsch, G. E.; Birnbaum, E. R. Inorg. Chem.
1
965, 4, 575; (b) Baldwin, R. A.; Washburn, R. M. J. Org.
Chem. 1961, 26, 3549.
1
2. Pereyre, M.; Quintard, J.-P.; Rahm, A. Tin in Organic
Synthesis; Butterworth: London, 1987; p 6.
Acknowledgements
1
3. (a) Ikenaga, T.; Matsushita, K.; Shinozawa, J.; Yada, S.;
Takagi, Y. Tetrahedron 2005, 61, 2105; (b) Heinen, A. W.;
Peters, J. A.; van Bekkum, H. Eur. J. Org. Chem. 2000,
2501; (c) Birtill, J. J.; Chamberlain, M.; Hall, J.; Wilson,
R.; Costello, I. In Catalysis of Organic Reactions; Herkes,
F. E., Ed.; Dekker: New York, 1998; p 255.
We are grateful to NSERC of Canada and to FESR of
University of Moncton for financial support of this
research.
References and notes
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1
2
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. Henkel, T.; Brunne, R. M.; Mueller, H.; Reichel, F.
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17. The aqueous phase obtained after the removal of solvents
was re-used with a fresh charge of the benzaldehyde
(2.5 mmol) and benzylamine (2.5 mmol).
4
. (a) Hutchins, R. O.; Hutchins, M. K. In Comprehensive
Organic Synthesis; Trost, B. M., Fleming, I., Eds.;
Pergamon: Oxford, 1991; Vol. 8, p 25; (b) Hudlicky, M.
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5
. (a) Lane, C. F. Synthesis 1975, 135; (b) Borch, R. F.;
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. Abdel-Magid, A. F.; Carson, K. G.; Harris, B. D.;
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18. Typical procedure for the reductive amination of alde-
hydes with amines: In a glass liner of a 45 mL autoclave
and under an atmosphere of nitrogen, Pd(PhCN) Cl
6
7
2
2
3
849.
(0.025 mmol) and BQC (0.15 mmol) were dissolved in
degassed water (10 mL) at room temperature. Then the
aldehyde (2.5 mmol) was introduced, followed by the
amine (2.5 mmol), and the resulting solution was white-
opaque. The autoclave was flushed several times with
. (a) Pelter, A.; Rosser, R. M.; Mills, S. J. Chem. Soc.,
Perkin Trans. 1 1984, 717; (b) Bomann, M. D.; Guch, I.
C.; DiMare, M. J. Org. Chem. 1995, 60, 5995.
8
9
. Suwa, T.; Sugiyama, E.; Shibata, I.; Baba, A. Synthesis
2
000, 558, and 789.
40 psi of N and then purged with hydrogen. After the
2
. (a) Sato, S.; Sakamoto, T.; Miyazawa, E.; Kikugawa, Y.
autoclave was pressurized to 200 psi of hydrogen, it was
Tetrahedron 2004, 60, 7899; (b) Cho, B. T.; Kang, S. K.
placed in an oil bath at 100 °C for 24 h. The autoclave was