E
S. Harada et al.
Letter
Synlett
Table 3 Conversion of Hydroperoxide 7b into Enone 5ba
O2 (balloon)
conditions
+
Ph
Ph
Ph
DMA (0.1 M)
rt
OOH
7b
O
5b
OH
6b
Entry
Ru(bpy)3(PF6)2(1 mol%) Cu(OTf)2(10 mol%)
TEMPO (1 equiv) Blue LED
Time (h)
7b
85
5b
trace
6b
1
2
3
4
5
6
–
–
–
+
+
+
–
+
+
+
+
–
–
–
+
+
+
+
OFF
OFF
OFF
OFF
ON
24
24
24
24
6
trace
<13b
9
58
6
19
57
61
64
7
14
0
13
<6b
4
ON
24
78
a Reaction conditions: 7b (0.1 mmol), Ru catalyst (1.0 mol), Cu(OTf)2 (0.01 mmol), TEMPO (0.1 mmol), DMA (1 mL), O2 atmosphere.
b Containing trace amounts of inseparable unknown byproducts.
cannot therefore exclude a mechanism in which the copper
salt catalyzes the direct conversion path (Figure 2, dotted
arrow).26
In conclusion, we have developed a new method for the
oxygenation of olefins that realizes the direct synthesis of
enones.27 Notably, the oxygen-containing functional group
was introduced regioselectively. The mild reaction condi-
tions were suitable for substrates bearing primary alcohols,
heteroaromatic rings, and potential leaving groups. A de-
tailed investigation of the reaction mechanism is ongoing.
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Funding Information
This work was supported by the Japan Society for the Promotion of
Science (JSPS) KAKENHI [Grant Numbers: 16K08154 and19K06991
(S.H.), 14J03297 (T.M.), and 17H03969 (A.N.)], the Tokyo Biochemical
Research Foundation [Grant Number 16-B1-5 (S.H.)], and the Sumito-
mo Foundation [Grant Number 190444 (S.H.)]. We also than the Insti-
tute for Global Prominent Research, Chiba University, for providing
financial support.
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(11) (a) Wei, W.; Liu, C.; Yang, D.; Wen, J.; You, J.; Suo, Y.; Wang, H.
Chem. Commun. 2013, 49, 10239. (b) Bag, R.; Sar, D.;
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Loh, T.-P. J. Am. Chem. Soc. 2015, 137, 42.
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Acknowledgment
We thank Mr. R. Masuda (Chiba University) for support with the re-
agent supply and for valuable discussions. We also thank Professors
Dr. M. Shibasaki and Dr. N. Kumagai (Institute of Microbial Chemistry)
for support with the photocatalysts.
Supporting Information
(13) Unless otherwise noted E-olefins were used for the substrate
scope experiments. See the Supplementary Information (SI) for
the difference in reactivity between the E- and Z-isomers.
(14) Demas, J. N.; Harris, E. W.; McBride, R. P. J. Am. Chem. Soc. 1977,
99, 3547.
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Supporting information for this article is available online at
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References and Notes
(1) (a) Moiseev, I. I.; Vargaftik, M. N. Coord. Chem. Rev. 2004, 248,
2381. (b) Nakamura, A.; Nakada, M. Synthesis 2013, 45, 1421.
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