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Pleas Ge rdeo e nn o Ct ah de j mu si ts mt r ya rgins
DOI: 10.1039/C6GC02156E
Journal Name
ARTICLE
Finally, we tackled the recovery and reuse of the catalyst, a
topic of particular interest to many synthetic chemists.
Conclusions
1
8, 19
We achieved transoximation to aldehydes and ketones
catalyzed by HClO under mild reaction conditions. The
reaction conditions were tolerated by several
Heterogeneous catalysts can often be recycled.
We
4
focused on recovering catalyst from reactions in which the
product was conveniently purified by filtration and washed
with water. Organic solvent is not required because both the
reagents and byproducts dissolve in water or are liquids. We
expected that the reaction filtrate could be reused repeatedly
to conduct the same reaction by simply adding aldehyde and
aromatic/aliphatic aldehyde and ketone substrates and gave
the desired aldoximes in good yield. Analysis of the reaction
mechanism suggested that this transoximation reaction
proceeded via hydroxylamine generated by the successive
hydrolysis of oxime, and both aldehyde and a trace amount of
water were essential to turn over the catalyst. Moreover, we
4
MEKO because the HClO catalyst would remain in the filtrate
as complex B. We applied this proposed approach to the
synthesis of 3j and demonstrated that the filtrate could be
reused more than ten times without the need to prepare new
catalyst or add additional water as a solvent (Figure 5). This
approach allows the reuse of both the homogeneous catalyst
and solvent (and residual staring material and reagents) if the
product becomes a solid and the starting material is a liquid or
consumed.
found that the homogeneous Brønsted catalyst could be
reused more than ten times by reusing the reaction filtrate.
These results will allow the use of stable oximes rather than
hydroxylamines, which require a stoichiometric amount of
base, thus avoiding the production of large amounts of
inorganic salt. Research is in progress to expand this approach
to other substrates.
OH
Me
OH
H
O
HClO
4
(5 mol%)
Acknowledgements
N
N
Ph
H
2
H O, r.t., 12 h
This work was financially supported by a Kaneka Award in
Synthetic Organic Chemistry, Japan, and by the Ministry of
Education, Culture, Sports, Science and Technology, Japan
(MEXT) as a Supported Program for the Strategic Research
Foundation at Private Universities (S1311040), and partially by
JSPS KAKENHI Grand in Scientific Research on Innovative Areas
“Photosynergetics” (JP26107012). We are also grateful to
Et
Ph
1
j
2d
3j
1
gram scale
ꢀ
Procedure for reusable reaction filtrate
1
00 mL flask, stirr bar, under N
2
H O
2
HClO4
1
8
aldehyde 1j & MEKO 2d
Stirred at r.t. for 12 h
Filtration and washed with H
Taiyo Nippon Sanso Co., Ltd., for providing H
2
O, and to Prof.
S. Nakamura, Mr. M. Kondo, Mr. N. Shiomi (Nagoya Institute of
Technology), Prof. M. Asano (Ryukoku University) for ESI-MS
measurements and Prof. T. Nakaoki (Ryukoku University) for
Karl-Fisher titration.
2
O
Filtrate solution
00 mL flask, stirr bar, under N2
1
aldehyde 1j & MEKO 2d
Stirred at r.t. for 12 h
Filtration and washed with H
2
O
Notes and references
‡
These authors contributed equally.
Product 3j
as a solid
Product 3j
Filtrate solution
10
1
Selected examples: (a) K. Ishihara, Y. Furuya and H.
Yamamoto, Angew. Chem. Int. Ed. 2002, 41, 2983-2986; (b)
K. Yamaguchi, H. Fujiwara, Y. Ogasawara, M. Kotani and N.
Mizuno, Angew. Chem. Int. Ed. 2007, 46, 3922-3925; (c) K.
Hyodo, S. Kitagawa, M. Yamazaki and K. Uchida, Chem. Asian
J. 2016, 11, 1348-1352.
(a) E. Beckmann, Ber. Dtsch. Chem. Ges. 1886, 19, 988-993;
(b) L. G. Donaruma and W. Z. Heldt, Org. React. 1960, 11, 1-
156. (c) R. E. Gawley, Org. React. 1988, 35, 1–420. (d) Y.
Furuya, K. Ishihara and H. Yamamoto, J. Am. Chem.
Above procedures were repeated total 10 times.
9
8
99
1
00
8
5
8
4
86
83
8
0
80
80
2
3
4
80
60
40
20
0
73
71
Soc. 2005, 127, 11240-11241.
Recent examples, (a) H. Sharghi and M. Hosseini, Synthesis,
2
002, 1057-1059; (b) H. Zhao, C. P. Vandenbossche, S. G.
Koenig, S. P. Singh and R. P. Bakale, Org. Lett. 2008, 10, 505-
507; (c) J. P. Waldo and R. C. Larock, Org. Lett. 2005, , 5203-
205.
U.S. Chemical Safety and Hazard Investigation Board, No.
999-13-C-PA.
7
5
1
1
2
3
4
5
6
7
8
9
10 11
5
6
7
H. Ichihashi, Catalysts Catal. 2005, 47, 190-195.
K. Yamafuji, 1953, 171, 745.
(a) K. Yamafuji, H. Omura, F. Yoshihara, M. Yoshitake and N.
Oyama, Enzymol. 1958, 19, 180-185; (b) H. Omura, T.
Yoshida, M. Munakata and K. Yamafuji, Sci. Bull. Fac. Agr.,
Kyushu Univ., 1960, 17, 411-428.
Cycle (time)
Figure 5. Recovery and reuse of reaction filtrates.
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