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ACS Catalysis
investigations of the present catalytic system to other
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reactions are ongoing in our laboratory.
ASSOCIATED CONTENT
Scheme 4. Deuterium Labelling Experiment
Supporting Information.
General experimental procedure and characterization of all
compounds are provided. This material is available free of
When we used hydrogen itself instead of carbon monoxide
under identical conditions, the expecting product was ob-
tained with a comparable yield (Scheme 5).
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AUTHOR INFORMATION
Corresponding Author
* E-mail; ykchung@snu.ac.kr
Scheme 5. Reductive Amination with Hydrogen Gas
Notes
The authors declare no competing financial interest.
The reusability of Co2Rh2/C was also examined for the
amination of 1a with 2a (Table 4). After reaction, the cata-
lyst was filtered from the reaction mixture, dried in vacu-
um, and reused for the further catalytic reaction. The cat-
alytic system is stable under the reaction conditions. The
catalyst maintained its high level of activity even after
being reused eight times (97%, 95%, 94%, 92%, 92%, 93%,
90%, and 92%, respectively); the maximum reusability
has not been tested.
ACKNOWLEDGMENT
This work was supported by a National Research Foundation
of Korea (NRF) grant funded by the Korean govern-
ment (2014R1A5A1011165 and 2007-0093864). JWP is a recipi-
ent of BK21 plus Fellowship.
REFERENCES
(1) For recent papers, see: (a) Xu, Z.; Yan, P.; Xu, W.; Jia, S.; Xia,
Z.; Chung, B.; Zhang, Z. C. RSC Adv. 2014, 4, 59083-59087. (b)
Zhu, M. Catal. Lett. 2014, 144, 1568-1572. (c) Zhou, S.; Fleischer,
S.; Jiao, H.; Junge, K.; Beller, M. Adv. Synth. Catal. 2014, 356, 3451-
3455.
Table 4. Reuse of Co2Rh2/C Catalyst for Reductive
Amination of 1a with 2a a
(2) For organocatalytic reductive amination using Brønsted acids in
combination with a Hantzsch ester, see: (a) Storer, R. I.; Carrera, D.
E.; Ni Y.; Macmillan, D. W. C. J. Am. Chem. Soc. 2006, 128, 84-86.
(b) Zhou, J.; List, B. J. Am. Chem. Soc. 2007, 129, 7498-7499. For
biocatalytic reductive amination, see: (c) Koszelewski, D.; Lavandera,
I.; Clay, D.; Guebitz, G. M.; Rozzell D.; Kroutil, W. Angew. Chem.,
Int. Ed. 2008, 47, 9337-9340. For hydrogen transfer in reductive ami-
nation, see: (d) Williams, G. D.; Pike, R. A.; Wade C. E.; Wills, M.
Org. Lett. 2003, 5, 4227-4230. (e) Kadyrov R.; Riermeier, T. H.
Angew. Chem., Int. Ed. 2003, 42, 5472-5474. For asymmetric reduc-
tive aminations catalyzed by transition metals, see: (f) Chi, Y.; Zhou
Y. G.; Zhang, X. J. Org. Chem. 2003, 68, 4120-4122. (g) Kadyrov, R.;
Riermeier, T. H.; Dingerdissen, U.; Tararov V.; Börner, A. J. Org.
Chem. 2003, 68, 4067-4070. (h) Chang, M.; Liu, S.; Huang K.;
Zhang, X. Org. Lett. 2013, 15, 4354-4357.
(3) For hydrogenation, see: (a) Pagnoux-Ozherelyeva, A.; Pan-
netier, N.; Mbaye, M. D.; Gaillard, S.; Renaud, J.-L. Angew.
Chem., Int. Ed. 2012, 51, 4976. (b) Nasrollahzadeh, M. New J.
Chem. 2014, 38, 5544-5550. For hydride reducing, see: (c) R. F.
Borch, M. D. Bernstein, H. D. Durst, J. Am. Chem. Soc. 1971, 93,
2897-2904. (d) Sato, S.; Sakamoto, T.; Miyazawa, E.; Kikugawa, Y.
Tetrahedron 2004, 60, 7899-7906.
(4) (a) Kadyrov, R.; Riermeier, T. H. Angew. Chem., Int. Ed. 2003,
42, 5472-5474. (b) Wang, C.; Pettman, A.; Basca, J.; Xiao, J. An-
gew. Chem., Int. Ed. 2010, 49, 7548-7552. (c) Wei, Y.; Wang, C.;
Jiang, X.; Xue, D.; Li, J.; Xiao, J. Chem. Commun. 2013, 49, 5408-
5410. (d) Talwar, D.; Salguero, N. P.; Robertson, C. M.; Xiao, J.
Chem. Eur. J. 2014, 20, 245-252.
(5) Chusov, D.; List, B. Angew. Chem., Int. Ed. 2014, 53, 5199-5201.
(6) Iqbal, A. F. M. Tetrahedron Letters 1971, 12, 37, 3385–3388.
(7) (a) Astruc, D.; Lu, F.; Aranzaes, J. R. Angew. Chem., Int. Ed.
2005, 44, 7852−7872. (b) Yan, N.; Xiao, C.; Kou, Y. Coord. Chem.
Rev. 2010, 254, 1179-1218. (c) Shylesh, S.; Schnemann, V.; Thiel,
W. R. Angew. Chem., Int. Ed. 2010, 49, 3428-3459. (d) Polshet-
Entry
Catalyst
Yield (%)b
1
Co2Rh2 5 mol%
97
95
94
92
92
93
90
92
2
3
4
5
6
7
8
Recovered from #1
Recovered from #2
Recovered from #3
Recovered from #4
Recovered from #5
Recovered from #6
Recovered from #7
a1a (1.0 mmol), 2a (1.0 mmol), H2O (0.03 mL), CO (5 atm), and
o
b
Co2Rh2 catalyst (5 mol%, 90 mg) in 3 mL THF at 100 C for 6 h. I-
solated yield.
In conclusion, we have developed the first Co2Rh2 nano-
particles/charcoal-catalyzed reductive amination of alde-
hydes and ketones with amines using a water-gas-shift
reaction instead of hydrogen. Advantageously, no compli-
cated ligands or additional acid or base is needed. The
reaction can be extended to the tandem reduction of al-
dehydes and ketones with nitroarenes. The experimental
simplicity and the reusability are especially attractive and
should encourage the use of this catalytic system among
synthetic chemists and in industrial application. Further
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