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ChemComm
Page 4 of 4
DOI: 10.1039/C6CC10200J
COMMUNICATION
Journal Name
Synlett, 2007, 11, 1675; (h) A. Taketoshi, A. Tsujimoto, S. Maeda,
T. Koizumi and T. Kanbara, ChemCatChem, 2010, , 58; (i) A.
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a)
R
b)
2
D
0.008
R
H
0.018
0.012
0.006
0.000
0.006
0.004
0.002
0.000
R
H
R
D
3
For leading references to synthesis of imines, see: (a) R. D. Patil
and S. Adimurthy, Adv. Synth. Catal., 2011, 353, 1695; (b) R. D.
0
40
80
120
160
0
40
80
120
160
200
Time (mins)
Patil and S. Adimurthy, RSC Adv., 2012,
M. Kerton, Org. Biomol. Chem. 2012, 10, 1618; (d) T. Sonobe, K.
Oisaki and M. Kanai, Chem. Sci., 2012, , 3249; (e) B. Huang, H.
Tian, S. Lin, M. Xie, X. Yu and Q. Xu, Tetrahedron Lett., 2013, 54
2, 5119; (c) Z. Hu and F.
Time (mins)
Figure 1. Kinetic isotope effect data for a)
PhCH2NH2 and isotopically labeled PhCD2NH2 to nitrile, b)
oxidation of PhCH2NH2 and isotopically labeled PhCD2NH2 to imine.
[
1a]ClO4 catalyzed oxidation of
]ClO4 catalyzed
[
2
3
,
2861; (f) E. Zhang, H. Tian, S. Xu,
X. Yu and Q. Xu, Org. Lett., 2013, 15, 2704; (g) K. T. V. Rao, B.
the same CH bond from sp2 to sp3 on attack of the second amine
molecule resulting in an aminal intermediate VI.14 Hammett studies
further predict a positively charged transition state in [1a]ClO4
catalyzed nitrile formation ( = 3.3, Figure 2a) while a change in
rate determining step as a function of various substituents is
operational in [2]ClO4 catalyzed imine formation (Figure 2b).15 The
abrupt change in the slope of the plot with two intersecting lines for
[2]ClO4 catalyzed imine formation indicates that electron-
withdrawing groups are assisting step 1, making step 2 rate-limiting
and alternatively, electron-donating groups increase the rate of
step 2, making step 1 rate-determining (cf. Scheme 3).
Haribabu, P. S. S. Prasad and N. Lingaiah, Green Chem., 2013, 15
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10613; (i) L. Aschwanden, B. Panella, P. Rossbach, B. Keller and
A. Baiker, ChemCatChem 2009, , 111; (j) L. Aschwanden, T.
Mallat, M. Maciejewski, F. Krumeich and A. Baiker,
ChemCatChem 2010, , 666; (k) J. S. M. Samec, A. H. Ell and J. E.
,
,
1
2
Bäckvall, Chem.-Eur. J., 2005, 11, 2327; (l) A. H. Ell, J. S. M.
Samec, C. Brasse and J. E. Bäckvall, Chem. Commun., 2002, 1144;
(m) A. H. Ell, J. B. Johnson and J. E. Bäckvall, Chem. Commun.,
2003, 1652.
J. Wang, S. Lu, X. Cao and H. Gu, Chem. Commun., 2014, 50,
5637.
Preparation, IR and NMR data of only [1c]ClO4 was previously
reported in: A. Santos, J. López, A. Galán, J. J. González, P. Tinoco
and A. M. Echavarren, Organometallics, 1997, 16, 3482.
(a) I. L. Fedushkin, N. M. Khvoinova, A. A. Skatova and G. K.
Fukin, Angew. Chem., Int. Ed., 2003, 42, 5223; (b) I. L. Fedushkin,
A. A. Skatova, V. A. Chudakova and G. K. Fukin, Angew. Chem.,
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(a) M. M. Khusniyarov, K. Harms, O. Burghaus and J.
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Zhao, Y. Su, J. Su, B. Wu and X.-J. Yang, Inorg. Chem., 2012, 51
4
5
b)
a)
p-OMe
p-OCF
3
0.8
0.6
0.8
0.6
0.4
0.2
0.0
p-OMe
0.4
p-Me
0.2
6
7
p-H
p-F
0.0
p-Me
p-F
-0.2
-0.4
p-OCF
p-H
3
-0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 0.05 0.10
-0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 0.05 0.10
Figure 2. Hammett plot: [log(kX/kH) versus for competitive oxidation of benzyl amine
and p-substituted benzyl amines for a) [1a]ClO4 catalyzed oxidation to nitrile, b) [2]ClO4
catalyzed oxidation to imine.
,
13162; (c) Q. Dong, J. Su, S. Gong, Q. Li, Y. Zhao, B. Wu and X.-J.
Yang, Organometallics, 2013, 32, 2866.
In conclusion, the present communication demonstrates for the
first time a ligand controlled catalytic system for the simultaneous
formation of nitriles and imines from primary amines as substrates.
Interestingly, such switchable selectivity can be attributed to the
varying -acidic feature of BIAN versus phen in the frameworks of
the catalysts. Overall, both the catalysts exhibit excellent functional
group compatibility; a wide variety of benzylic and aliphatic primary
amines were well-tolerated under the present reaction conditions.
Reports on ruthenium catalyzed aerobic oxidation of amines are
scarce and therefore, the present protocols provide excellent
alternatives to the traditional procedures.
8
(a) K.-N. T. Tseng, A. M. Rizzi and N. K. Szymczak, J. Am. Chem.
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Lett., 2014, 55, 5504.
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Financial support received from DST and UGC (fellowship to R. R.),
India, are gratefully acknowledged.
Notes and references
1
For recent reviews on oxidation of amines, see: (a) M. T.
Schumperli, C. Hammond and I. Hermans, ACS Catal., 2012,
1108; (b) B. Chen, L. Wang and S. Gao, ACS Catal., 2015, , 5851.
For leading references to synthesis of nitriles, see: (a) J. Kim and
S. S. Stahl, ACS Catal., 2013, , 1652; (b) K. Yamaguchi and N.
2,
14 (a) M. J. Tanner, M. Brookhart and J. M. DeSimone, J. Am. Chem.
Soc., 1997, 119, 7617; (b) B. Patrick Sullivan and T. J. Meyer,
5
2
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4 | J. Name., 2012, 00, 1-3
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