Page 3 of 5
Journal Name
RSC Advances
DOI: 10.1039/C4RA08764J
a Reaction conditions: Unless otherwise noted, 1 (0.2 mmol), Et4NI (0.005
mmol, 2.5 mol%), NaIO4 (0.6 mmol, 3 equiv.), MeCN (0.8 mL) and H2O (0.2
mL) were stirred at 105 oC (oil bath temperature) for 12 h in a sealed tube.
Isolated yield. b The reaction was performed at 130 oC for 15 h. c cisꢀalkene.
roles, serving as epoxidation and nucleophilic deformylation
regents. The further application of this methodology to other
reactions is now in progress in our laboratory.
We thank the Chinese Academy of Sciences and the National
Natural Science Foundation of China (21133011 and 21103207).
Notes and references
State Key Laboratory for Oxo Synthesis and Selective Oxidation,
reaction took place [Scheme 3, (I)]. Taking into account that NaIO4
could be used as an oxidant for the epoxidation of olefins,16 epoxide
may be an intermediate of the present catalytic system. We were
delighted to find that transꢀstilbene oxide was converted to desired
enzophenone in good yield (Scheme 3, (II)). 2ꢀIodoꢀ1,2ꢀ
diphenylethanol was thought to be a further intermediate generated
from the ringꢀopening of transꢀstilbene oxide, but it could not be
synthesized because of its instability. Accordingly, 2ꢀbromoꢀ1,2ꢀ
a
Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences,
Lanzhou,730000, China. Eꢀmail: wsun@licp.cas.cn.
b
College of Biological, Chemical Sciences and Engineering, Jiaxing
University, Jiaxing, 314001, China.
Electronic Supplementary Information (ESI) available: [Experimental
procedures, NMR data and spectra of the products, GCꢀMS of mechanism
study]. See DOI: 10.1039/c000000x/
diphenylethanol
5 instead of 2ꢀiodoꢀ1,2ꢀdiphenylethanol was
examined in the presence of NaIO4 to give the benzophenone in 95%
yield in the absence of Et4NI [Scheme 3, (III)].
1
a) R. A. Sheldon, J. K. Kochi, Metal Catalyzed Oxidations of
Organic Compounds, Academic Press, New York, 1981; b) R.
Stewart, Oxidation in Organic Chemistry, Wiberg, K. Ed., Academic
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2
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Pariza, Chem. Rev., 2006, 106, 2990.
Scheme 3. Control experiments for proving the mechanism.
On the basis of these studies, the following tentative mechanism for
this transformation is proposed (Scheme 4). Firstly, epoxide A was
17
formed in the presence of Et4NI/NaIO4 and then it could be
transferred to B via ringꢀopening reaction. The loss of iodide from B
gives a carbocation intermediate C, which undergoes rearrangement
to provide a more stable aldehyde D.18 For the reaction of transꢀ
3
4
R. Pappo, Jr., D. S. Allen, R. U. Lemieux, W. S. Johnson, J. Org.
Chem., 1956, 21, 478.
stilbene,
the
corresponding
transꢀstilbene
oxide
and
diphenylacetaldehyde could be observed during the reaction by GCꢀ
MS and 1H NMR (see Supporting Information, Figure S1ꢀ7).
Subsequently, aldehyde deformylation by a nucleophilic reaction
with NaIO4 takes place, providing the desired diarylketone 2, along
with the release of formic acid.19
a) W. P. Griffith, A. G. Shoair, M. Suriaatmaja, Synth. Commun.
,
2000, 30, 3091; b) B. Plietker, J. Org. Chem., 2003, 68, 7123; c) C.ꢀ
M. Ho, W.ꢀY. Yu, C. ꢀM. Che, 3365; Angew. Chem. Int. Ed., 2004,
43, 3303; d) D. Yang, C. Zhang, J. Org. Chem., 2001, 66, 4814.
D. Xing, B. Guan, G. Cai, Z. Fang, L. Yang, Z. Shi, Org. Lett., 2006,
5
8, 693.
6
7
A. Wang, H. Jiang, J. Org. Chem., 2010, 75, 2321.
B. R. Travis, R. S. Narayan, B. J. Borhan, J. Am. Chem. Soc., 2002,
124, 3824.
8
9
W. P. Griffith, Coord. Chem. Rev., 2001, 219–221, 259.
a) K. Miyamoto, N. Tada, M. Ochiai, J. Am. Chem. Soc., 2007, 129
,
2772; b) K. Miyamoto, Y. Sei, K. Yamaguchi, M. Ochiai, J. Am.
Chem. Soc., 2009, 131, 1382; c) P. P. Thottumkara, T. K. Vinod,
Org. Lett., 2010, 12, 5640.
Scheme 4 Tentative mechanism for cascade oxidative cleavage of various
alkenes.
10 a) R. Lin, F. Chen, N. Jiao, Org. Lett., 2012, 14, 4158; b) T. Wang,
N. Jiao, J. Am. Chem. Soc., 2013, 135, 11692; c) C. X. Miao, B. Yu,
L. N. He, Green Chem., 2011, 13, 541.
Conclusions
In summary, we have developed an Et4NIꢀcatalyzed method for
the synthesis of symmetrical/unsymmetrical diaryl ketones
from stilbenes, through merging of oxidative cleavage and
recombination of aromatic groups with NaIO4. Through the
mechanistic studies in this transformation, NaIO4 may play dual
11 C. E. Paul, A. Rajagopalan, I. Lavandera, V. GotorꢀFernández, W.
Kroutil, V. Gotor, Chem. Commun., 2012, 48, 3303.
12 N. Sharma, A. Sharma, R. Kumar, A. Shard, A. K. Sinha, Eur. J.
Org. Chem., 2010, 6025.
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