Synlett 2010(13): 1979-1983  
DOI: 10.1055/s-0030-1258134
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Direct Synthesis of 1,2-Diketones by Catalytic Aerobic Oxidative Decarboxylation of 1,3-Diketones with Iodine and Base under Irradiation of Fluorescent Light

Norihiro Tada, Motoki Shomura, Hiroki Nakayama, Tsuyoshi Miura, Akichika Itoh*
Gifu Pharmaceutical University, 1-25-4, Daigaku-nishi, Gifu 501-1196, Japan
Fax: +81(58)2308108; e-Mail: itoha@gifu-pu.ac.jp;
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Publikationsverlauf

Received 27 April 2010
Publikationsdatum:
09. Juli 2010 (online)

Abstract

We report a catalytic direct synthesis of 1,2-diketone from 1,3-diketone through iodine/base-catalyzed aerobic photo­oxidation under visible-light irradiation of fluorescent lamp.

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Typical Procedure
A solution of dibenzoylmethane (1a, 0.3 mmol), I2 (0.003 mmol), and Ca(OH)2 (0.15 mmol) in dry EtOAc (5 mL) in a Pyrex test tube, purged with an O2 balloon, was stirred and irradiated externally with four of 22 W fluorescent lamps for 10 h. The reaction mixture was concentrated under reduced pressure. The pure product 2a was obtained by preparative TLC.

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Iodide 5, which is provided by alternative method, is converted into 2a in 66% yield under our standard conditions in the absence of I2.