Oxidation of 1,2-diketones

The few kinetic studies of the oxidation of 1,2-diketones indicate that the mechanism differs from that found for the oxidation of 1,2-diols, and that, contrary to earlier suggestions, the reaction does not proceed via a hydrate of the diketone. Shiner and Wasmuth studied the oxidation of butane-2,3-dione, 

RATE COEFFICIENTS FOR THE OXIDATION OF SOME 1,2 DIKETONES BY VARIOUS 

The actual presence of a cyclic periodate ester or other intermediate has not been demonstrated experimentally. Dahlgren and Reed suggest that the general base catalysis could be due either to an interaction of the catalyst with periodate in a prior equilibrium, or to proton abstraction prior to formation of the cyclic ester. 

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Dahlgren and Reed ). Shiner and Wasmuth suggest that the oxidation of 1,2-diketones proceeds via a cyclic periodate ester, similar to that postulated for the oxidation of 1,2-diols, but formed by nucleophilic attack of periodate on carbon, viz. 

Only one kinetic study has been reported. The oxidation of 3-hydroxy-3-methyl-butane-2-one is second-order with a rate maximum at pH 8 (Bunton and Shiner ). The same authors carried out an experiment at pH 8 which shows that the C-OH bond is not broken, as in the oxidation of 1,2-diols. The mode of attack on the carbonyl group is probably nucleophilic at the carbon atom, as in the oxidation of 1,2-diketones. 

Diaza-l,6-dioxa-6fl-tellurapentalenes 97 were obtained in 4—60% yields by oxidation of 1,3-diketone dioximes with tellurium dioxide (79BSF199). 

A procedure for the preparation of 1,2-diketone derivatives has been devised whereby the hydrazone of an a-chloroketone is converted into the corresponding azide. Further oxidation with trifluoroacetic acid yields the diketone product209. 

Another type of oxidative (formal) cycloaddition is exemplified by the oxidation of 1,3-diketones in MeCN in the presence of an olefin to di- or tetrahydrofuran derivatives [136] similar products may be obtained by reduction of 2,2-dibromo-1,3-diketones in the presence of an alkene [136]. 

This diketone was obtained by selenium dioxide oxidation of 1-(2-furyl)-2-propanone (1.79) (17% yield) or of l-(2-furyl)-l-propanone (1.75) (4% yield) (Cosgrove et al., 1952). It was prepared by Gianturco et al. (1964b), in 60% overall yield, by acid-catalyzed hydrolysis (or by transoximation) of... 

Oxidation of 1,2-diols. a-Diketones are produced by the reaction of glycols with... 

The oxidative cleavage of 1,2-diketones to carboxylates has been reported to occur under 0 in the presence of metallic copper in... 

The first iodine-catalyzed synthesis of 2-alkyl substituted oxazoles 130 by a decarboxylative domino reaction was reported. Aryl methyl ketones 128 were transformed in situ into a-iodo ketones and then, by the Kornblum oxidation, into 1,2-diketones. After the addition of the a-amino acid 129, an l2-mediated cyclization/decarboxylation gave oxazoles 130. The reaction proceeds better if the Ar has electron-donating substituents and if the R group is a branched alkyl chain or phenyl residue. The reaction used oxone to regenerate iodine (13JOC6065). 

The present Grignard-type addition may be reasonably explained by smooth oxidative addition of benzyl halides to nickel in the metallic state to give benzylnickel halide intermediates, and the insertion of 1,2-diketone into the carbon-nickel bond would afford the corresponding hydroxy ketones after hydrolysis. 

Oxidation of Alkynes, Alkenes, and Benzylic Hydrocarbons. The yields of 1,2-diketones from the oxidation of acetylenes by potassium permanganate under aqueous conditions are substantially improved by buffering (pH 7—7.5) the reaction mixture.However, potassium permanganate-phase transfer catalyst in... 

The interaction of 1,2-diketone dioximes with an excess of diselenium dichloride in DMF yields 1,2,5-selenadiazole A -oxides, a reaction that is comparable with the corresponding synthesis of 1,2,5-thiadiazole JV-oxides (see Vol. 2, p. 753). 2,1,3-Benzoselenadiazole 7V-oxide (184), similarly obtained from the dioxime (183), undergoes thermolysis in decalin to give 2,1,3-benzoselenadiazole (185)... 

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