Oxidations with lead tetraacetate. II. Oxidations of 2,2-disubstituted 1,3-benzodioxoles

Abstract

The oxidation of 2,2-disubstituted 1,3-benzodioxoles by lead tetraacetate proceeds readily to give 5-acetoxy and 5,6-dione derivatives as main products. 5,6-Diacetoxy compounds and 5-carboxy derivatives are found in some instances as minor products. Oxidation of benzodioxoles substituted at the 5 and 6 positions with methoxyl groups or with a second dioxole ring results in oxidative loss of the dioxole ring. Relative effects of these substitutions on reactivity have been evaluated. The mechanism of o-quinone formation is discussed and is postulated to occur via a tetraacetoxy intermediate. The 5-acetoxy derivatives and the o-quinones, by hydrolysis and reduction respectively, serve as sources of 5-hydroxy and 5,6-dihydroxy benzodioxoles.