Abstract
A methyl group at the aromatic nucleus can be oxidized to the corresponding carboxylic
acid directly in the presence of N-bromosuccinimide (NBS) under photoirradiation. By considering both the promoting
effect of oxygen and a catalytic amount of NBS, aerobic oxidation via hydroperoxide,
which is thought to be generated by abstraction of a hydrogen with a bromo radical
from NBS, proceeded.
Key words
oxidations - methyl group -
N-bromosuccinimide - photoirradiation - molecular oxygen
References
<A NAME="RF03803SS-1">1</A>
Murahashi S.-I.
Angew. Chem., Int. Ed. Engl.
1995,
34:
2443
<A NAME="RF03803SS-2A">2a</A>
Sheldon RA.
Kochi JK. In
Metal-Catalyzed Oxidations of Organic Compounds
Academic Press;
New York:
1981.
<A NAME="RF03803SS-2B">2b</A>
Barton DHR.
Doller D.
Acc. Chem. Res.
1992,
25:
504
<A NAME="RF03803SS-2C">2c</A>
Shilov AE.
Shul’pin G.
Chem. Rev.
1997,
97:
2879
<A NAME="RF03803SS-2D">2d</A>
Murahashi S.-I.
Zhou X.-G.
Komiya N.
Synlett
2003,
321
<A NAME="RF03803SS-3A">3a</A>
Friedman N.
Gorodestsky M.
Mazur Y.
J. Chem. Soc., Chem. Commun.
1971,
874
<A NAME="RF03803SS-3B">3b</A>
Finucane BW.
Thomson JB.
J. Chem. Soc., Perkin Trans. 1
1972,
1856
<A NAME="RF03803SS-4">4</A>
Ivanov SK.
Kalitchin ZD.
Hinkova MK.
Oxid. Commun.
1983,
3:
89
<A NAME="RF03803SS-5">5</A>
Itoh A.
Kodama T.
Inagaki S.
Masaki Y.
Org. Lett.
2000,
2:
2455
<A NAME="RF03803SS-6">6</A>
The corresponding aldehydes (6-7%) and inseparable products were formed, respectively.
<A NAME="RF03803SS-7">7</A>
4-tert-Butylbenzaldehyde was oxidized to 2 in 93% yield under the same reaction conditions.