8
250 Huang et al.
Asian J. Chem.
95
90
85
4000000
3000000
2000000
1000000
0
g = 2.14
–1000000
–2000000
–3000000
–4000000
80
7
5
0
7
2000
2500
3000
3500
4000
4500
5000
1
2
3
4
Magnetic field (G)
Used times of co-catalysts in the reductio of hypnone
Fig. 1. Electron paramagnetic resonance curve of the Co-doped ammonia
borane sample
Fig. 2. Recyclability of Co-based catalysts
ACKNOWLEDGEMENTS
spin-lattice relaxation at room temperature. It was very likely
+
Financial support was provided by Science and Techno-
logy Bureau Foundation Project of Changsha (Grant No.
K1113005-31).
that part of Co element was in Co state.
2+
When the reaction completed, the cobalt was back to Co
state, according to electron paramagnetic resonance charac-
terization. Further investigations on the chemical state of Co
element and the reaction mechanism are needed.
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2
5
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Conclusion
Here we have reported a selective and new procedure for
chemoselective reduction of carbonyl compounds to corres-
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stable reagent, excellent yields, mild conditions, operational
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Characterization results of Co-doped ammonia borane show
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