T. Amaya et al. / Tetrahedron Letters 54 (2013) 2409–2411
2411
Commun. 2001, 461–462; (f) Yamaguchi, K.; Mizuno, N. Angew. Chem., Int. Ed.
(a)
2003, 42, 1480–1483; (g) Yamaguchi, K.; Mizuno, N. Chem. Eur. J. 2003, 9, 4353–
4361; (h) Maeda, Y.; Nishimura, T.; Uemura, S. Bull. Chem. Soc. Jpn. 2003, 76,
2399–2403; (i) Samec, J. S. M.; Éll, A. H.; Bäckvall, J.-E. Chem. Eur. J. 2005, 11,
Ph
Ph
N
Ph
Ph
PMAS (red)/Au NPs
under Ar
PMAS (half ox)/Au NPs
2327–2334; (j) Wang, J.-R.; Fu, Y.; Zhang, B.-B.; Cui, X.; Liu, L.; Guo, Q.-X.
Tetrahedron Lett. 2006, 47, 8293–8297; (k) Kotani, M.; Koike, T.; Yamaguchi, K.;
Mizuno, N. Green Chem. 2006, 8, 735–741; (l) Zhu, B.; Angelici, R. J. Chem.
Commun. 2007, 2157–2159; (m) Murahashi, S.-I.; Okano, Y.; Sato, H.; Nakae, T.;
Komiya, N. Synlett 2007, 1675–1678; (n) Zhu, B.; Lazar, M.; Trewyn, B. G.;
Angelici, R. J. J. Catal. 2008, 260, 1–6; (o) Mizuno, N.; Yamaguchi, K. Catal. Today
H
N
PMAS/Au NPs
2008, 132, 18–26; (p) Jiang, G.; Chen, J.; Huang, J.-S.; Che, C.-M. Org. Lett. 2009,
1
1, 4568–4571; (q) Kodama, S.; Yoshida, J.; Nomoto, A.; Ueta, Y.; Yano, S.;
Ueshima, M.; Ogawa, A. Tetrahedron Lett. 2010, 51, 2450–2452; (r) Lang, X.; Ji,
H.; Chen, C.; Ma, W.; Zhao, J. Angew. Chem., Int. Ed. 2011, 50, 3934–3937; (s)
Patil, R. D.; Adimurthy, S. Adv. Synth. Catal. 2011, 353, 1695–1700; (t) Sonobe,
T.; Oisaki, K.; Kanai, M. Chem. Sci. 2012, 3, 3249–3255.
(a) Aschwanden, L.; Mallat, T.; Grunwaldt, J.-D.; Krumeich, F.; Baiker, A. J. Mol.
Catal. A 2009, 300, 111–115; (b) Aschwanden, L.; Panella, B.; Rossbach, P.;
Keller, B.; Baiker, A. ChemCatChem 2009, 1, 111–115; (c) Aschwanden, L.;
Mallat, T.; Krumeich, F.; Baiker, A. J. Mol. Catal. A 2009, 309, 57–62; (d) Grirrane,
A.; Corma, A.; Garcia, H. J. Catal. 2009, 138–144; (e) So, M.-H.; Liu, Y.; Ho, C.-M.;
Che, C.-M. Chem. Asian J. 2009, 4, 1551–1561; (f) Aschwanden, L.; Mallat, T.;
Maciejewski, M.; Krumeich, F.; Baiker, A. ChemCatChem 2010, 2, 666–673; (g)
Miyamura, H.; Morita, M.; Inasaki, T.; Kobayashi, S. Bull. Chem. Soc. Jpn. 2011,
84, 588–599.
After the reaction of PMAS/Au
NPs with (PhCH
2
)
2
NH under Ar
2.
300
400
500
600
700
800
Wavelength (nm)
(b)
PMAS (red)/Au NPs
O2
3
.
.
(a) Li, C.-J.; Chen, L. Chem. Soc. Rev. 2006, 35, 68–82; (b) Chanda, A.; Fokin, V. V.
Chem. Rev. 2009, 109, 725–748; (c) Butler, R. N.; Coyne, A. G. Chem. Rev. 2010,
110, 6302–6337.
PMAS (half ox)/Au NPs
H O or H O
2 2 2
4
(a) Woo, J. C. G.; Wang, X.; Silverman, R. B. J. Org. Chem. 1995, 60, 6235–6236;
(
b) Perosa, A.; Selva, M.; Tundo, P. Tetrahedron Lett. 1999, 40, 7573–7576; (c)
Chen, X.; Wiemer, D. F. J. Org. Chem. 2003, 68, 6108–6114; (d) Hu, Z.; Kerton, F.
M. Org. Biomol. Chem. 2012, 10, 1618–1624; (e) Yuan, H.; Yoo, W.-J.; Miyamura,
H.; Kobayashi, S. J. Am. Chem. Soc. 2012, 134, 13970–13973.
After stirring under air
5.
4 2 2 8
The catalytic system of NiSO /K S O /NaOH was employed to oxidize
dibenzylamine in water, resulting in the corresponding imine as a minor
product (31% yield) with benzonitrile as a main product (59% yield), see:
Yamazaki, S. Chem. Lett. 1992, 823–826.
Shimizu, S.; Saitoh, T.; Uzawa, M.; Yuasa, M.; Yano, K.; Maruyama, T.;
Watanabe, K. Synth. Met. 1997, 85, 1337–1338.
After the reaction of PMAS/Au
NPs with (PhCH
2
)
2
NH under Ar
6
.
.
7
Saio, D.; Amaya, T.; Hirao, T. Adv. Synth. Catal. 2010, 352, 2177–2182.
300
400
500
600
700
800
8. Amaya, T.; Ito, T.; Inada, Y.; Saio, D.; Hirao, T. Tetrahedron Lett. 2012, 53, 6144–
147.
Amaya, T.; Ito, T.; Hirao, T. Heterocycles 2012, 86, 927–932.
6
Wavelength (nm)
9.
1
0. The transmission electron microscopy (TEM) image and the diameter
histogram of the PMAS/Au NPs are shown in Ref. 8.
Figure 1. UV–vis spectra of (a) PMAS/Au NPs (blue line) and after the reaction of
PMAS/Au NPs with dibenzylamine under Ar (vermilion line), and (b) PMAS (red)/Au
11. Imine products for entries 1–9 in Table 1 are known although NMR data of N-
À4
1
NPs under Ar (vermilion line) and after stirring under air (green line) (1.0 Â 10
M
(4-bromobenzylidene)-4-methylaniline are shown as follows:
(400 MHz, CDCl
J = 8.2 Hz), 7.60 (d, 2H, J = 8.2 Hz), 7.77 (d, 2H, J = 8.2 Hz), 8.42 (s, 1H);
NMR (100 MHz, CDCl ) 21.2, 120.9, 125.8, 130.0, 130.2, 132.1, 135.4, 136.3,
49.1, 158.2 ppm.
H NMR
based on the aniline monomer unit, 25 °C).
) d 2.38 (s, 3H), 7.14 (d, 2H, J = 8.2 Hz), 7.20 (d, 2H,
3
13
C
3
1
dehydrogenative oxidation reaction. Further investigation of this
system is now underway.
1
2. A general procedure for the catalytic aerobic dehydrogenative oxidation: A
5 mL two-necked flask was evacuated and backfilled with molecular oxygen.
Then,
a substrate (0.2 mmol) and 1 mL of PMAS/Au NPs solution (Au:
0
.01 mmol, 5 mol %) were added at room temperature. The mixture was
Acknowledgment
stirred at 60 °C under oxygen atmosphere for 40 h. The reaction mixture was
extracted with ethyl acetate. The organic layer was evaporated and examined
1
This work was partially supported by a Grant-in-Aid for Scien-
tific Research on Innovative Areas ‘Advanced Molecular Transfor-
mations by Organocatalysts’ from The Ministry of Education,
Culture, Sports, Science, and Technology, Japan.
by H NMR analysis (JEOL ECS-400, 400 MHz) with 1,3,5-trimethoxybenzene as
an internal standard.
3. (a) Yamamoto, T.; Ushiro, A.; Yamaguchi, I.; Sasaki, S. Macromolecules 2003, 36,
075–7081; (b) Strounina, E. V.; Shepherd, R.; Kane-Maguire, L. A. P.; Wallace,
G. G. Synth. Met. 2003, 135–136, 289–290.
4. Borrmann, T.; Dominis, A.; McFarlane, A. J.; Johnston, J. H.; Richardson, M. J.;
Kane-Maguire, L. A. P.; Wallace, G. G. J. Nanosci. Nanotechnol. 2007, 7, 4303–
1
1
1
7
References and notes
4
310.
5. In the previous paper (Ref. 8) concerning about the related oxidation of cyclic
secondary amines, the oxidation state of Au NPs was investigated using X-ray
photoelectron spectra (XPS) to show the Au(0) dominant in both before and
after the reaction.
1
.
(a) Nishinaga, A.; Yamazaki, S.; Matsuura, T. Tetrahedron Lett. 1988, 33, 4115–
118; (b) Porta, F.; Crotti, C.; Cenini, S. J. Mol. Catal. 1989, 50, 333–341; (c)
4
Bailey, A.; James, B. R. Chem. Commun. 1996, 2343–2344; (d) Minakata, S.;
Ohshima, Y.; Takemiya, A.; Ryu, I.; Komatsu, M.; Ohshiro, Y. Chem. Lett. 1997,
3
11–312; (e) Mori, K.; Yamaguchi, K.; Mizugaki, T.; Ebitani, K.; Kaneda, K. Chem.