Thallium reagents oxidative rearrangment

Similar oxidative rearrangements to produce carbonyl compounds have been carried out with thallium(III) nitrate557 or peroxytrifluoroacetic acid-BF3.558 The Jones reagent (Cr03—H2S04) in the presence of a catalytic amount of Hg(II) is also effective.559 Chromyl chloride oxidation, when combined with reductive workup, is a simple, convenient one-step method to convert 2,2-disubstituted 1-alkenes to aldehydes.560,561... 

The oxidative rearrangement of cyclic alkenes and ketones often leads to ring expansion or ring contraction reactions. The reagents generally used for this purpose are hypervalent main group oxidants such as thallium(III), lead(lV), iodine(III) and selenium(IV), alAough palladium(II) has been used as well. 

Mercuric salts induce oxidative rearrangement of cyclic alkenes and give cycloalkane carboxaldehydes. Cyclohexene, for example, gave cyclopentane carboxaldehyde (404) in 53% yield. Acyclic alkenes such as 2-butene can also be oxidized with mercuric sulfate and sulfuric acid, giving 2-butanone in this case.566 Thallium nitrate [T1(N03)3] is an important reagent for the oxidative rearrangement of cyclic alkenes.567 The reaction is not restricted to carbocyclic compounds, but can also be applied to heterocyclic compounds as shown by the oxidation of 3,4-dihydro-277-pyran (405) to the dimethyl acetal (406) in 65% yield.568... 

E. C. Taylor, A. McKillop, and coworkers. Thallium in organic synthesis 49. Oxidative rearrangement of chalcone dimethylketals to methyl-2,3-diaryl-3-methoxypropanoates with thallium(m) trinitrate in trimethylorthoformate. J. Org. Chem., 1977, 42, 4167 50. A convenient synthesis of thallium(i) cyanide, a useful reagent in organic synthesis (for conversion of aroyl chlorides to aromatic a-ketonitriles). J. Org. Chem., 1978, 43, 2280 51. Oxidation of enolizable ketones to a-nitratoketones by thallium(in) nitrate in acetonitrile. 

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