Gu, Liu & Zhang
FULL PAPER
Sharma, A.; Kumar, R.; Shard, A.; Sinha, A. K. Eur. J. Org. Chem.
2010, 2010, 6025; (g) Xing, D.; Guan, B.; Cai, G.; Fang, Z.; Yang, L.;
Shi, Z. Org. Lett. 2006, 8, 693; (h) Wang, T.; Jiao, N. J. Am. Chem.
Soc. 2013, 135, 11692.
Without Cu(OAc)2, the reaction of benzil 3a with
aniline could give α-imine ketone 5a in 58% yield in the
presence of Na2CO3 (1 equiv.) at 60 ℃ in EtOAc un-
der an O2 atmosphere (Eq. 5). With the aid of Cu(OAc)2,
α-imine ketone 5a could generate benzophenone 2a in
97% yield at 120 ℃. These experiments indicate that
α-imine ketone 5a may be involved in this process. Al-
though the detail reaction mechanism is still unclear,
further investigation is ongoing in our laboratory.
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Org. Chem. 2001, 66, 4504; (b) Biradar, A. V.; Sathe, B. R.; Um-
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Kinneary, J. F.; Albert, J. S.; Burrows, C. J. J. Am. Chem. Soc. 1988,
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Shard, A.; Sinha, A. K. Eur. J. Org. Chem. 2010, 6025.
[4] (a) Lin, R.; Chen, F.; Jiao, N. Org. Lett. 2012, 14, 4158; (b) Miya-
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[5] (a) Shi, Z.; Zhang, C.; Jiao, N. Chem. Soc. Rev. 2012, 41, 3381; (b)
Liang, Y.; Jiao, N. Angew. Chem., Int. Ed. 2014, 53, 548; (c) Liu, J.;
Liu, Q.; Yi, H.; Qin, Q.; Bai, R.; Qi, X.; Lan, Y.; Lei, A. Angew.
Chem., Int. Ed. 2014, 53, 502; (d) Wang, L.; Zhang, W.; Zeng, S.; Su,
D.; Meng, X.; Xiao, F. Chin. J. Chem. 2012, 30, 2189; (e) Lu, Q.;
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2014, 52, 7152; (f) Zhou, X.; Ji, H. Chin. J. Chem. 2012, 30, 2103;
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Conclusions
In summary, the chemoselective oxidative cleavage
of the C-C double bond of 1,2-diarylalkenes that yields
ketones has been described. The application of selective
C-C double bond cleavage in organic synthesis presents
one of the most attractive and challenging projects. A
wide range of 1,2-diarylalkenes can be subjected to this
palladium/copper-catalyzed method under an oxygen
atmosphere; the oxidation terminates at the ketone stage.
Preliminary mechanistic studies disclosed an interesting
reaction sequence, involving dihydroxylation of ole-
fins/oxidation/hydration/1,2-aryl migration/C-C bond
cleavage. Mechanistic, scope, and limitation studies of
the reaction are in progress in our laboratory.
Acknowledgement
We are grateful for the financial support from the
State Ethnic Affairs Commission (No. 12YNZ05);
Opening Fund of Key Laboratory of Ethnic Medicine
Resource Chemistry (No. MZY 1117).
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[7] Gu, L.; Liu, J.; Zhang, L.; Xiong, Y.; Wang, R. Chin. Chem. Lett.
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[8] For selected examples of Cu-catalyzed reactions, see: (a) He, C.;
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Zhang, C.; Jiao, N. Org. Chem. Front. 2014, 1, 109; (c) Chen, K.;
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Chin. J. Chem. 2012, 30, 2483; (g) Maji, A.; Rana, S.; Akanksha;
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Chin. J. Chem. 2014, 32, 1267—1270