Thallium triacetate oxidation with

Oxidation of enamines derived from cyclic and acyclic ketones with thallium triacetate in equivalent amount leads to the formation of the corresponding 2-acetoxy ketones75 (Scheme 52). The reactions are stereoselective (the antiparallel attack of the oxidizing agent is preferred over a parallel attack on 3- and 4-/-butylcyclohexanone enamines) and the attack occurs preferentially at the tetrasubstituted enamine double bond, when there is more than one possibility due to isomerism. 

Oxidathedetuageefeyek openes. 1,3,3-Trimethylcyclopropene (1) is converted into l,l-diacetoxy-2,3-dimethy 1-2-butene (2) by oxidation with mercuric acetate in methylene chloride at room temperature. Reaction of (1) with thallium triacetate or... 

The oxidation of isobutylene with thallium triacetate gives 82% of isobutylene oxide [412]. The oxidation of 1-pentene with peroxytrifluo-roacetic acid yields 81% of propyloxirane [283]. The electrooxidation of... 

Yields are generally higher than those obtained by direct oxidation of the ketones with thallium triacetate or lead tetraacetate. The reaction is also stereospecific. Thus oxidation of the morpholine enamine of 4-/-butylcyclohexanone gives only trans-2-acetoxy-4-t-butylcyclohexanone. 

Oxidative rearrangement of chalcones. 4-Methoxychalcone (1) on treatment with thallium triacetate in boiling methanol is converted into the 1,2-diaryl-3,3-dimethoxy-... 

It has been postulated that intermediates containing Si-Tl bond are formed during the oxidation of aryldimethylsilanes (43) with thallium triacetate. The silicon acts as a nucleophile toward Tl(III). However, the following mechanism consisting of a HSAB-matched transition state appears to be a better description. 

The presence of three hydroxyl groups per glucose unit was shown by the preparation of a triacetate and a tribenzoate. Six or seven methyla-tions (using dimethyl sulfate and concentrated alkali) of dextran did not raise the methoxyl content above 41% (theoretical maximum 45.6%). Also, Purdie methylations (using methyl iodide and silver oxide) and methylation with thallium ethoxide and methyl iodide were ineffective in raising the methoxyl content of methylated dextran above 43.5%. The maximum theoretical methoxyl content was eventually attained by modified Muskat methylations. 6 Partially methylated dextran suspended in anisole solution was treated with sodium in liquid ammonia, and the sodium salt of methylated dextran thus formed was allowed to react with methyl iodide. The methoxyl content of the partially methylated dextran was raised by three such methylations from 42% to 45.5% and by five such methylations from 30% to 45.4%. 

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