Oxidative C-demethylation in phenols

Abstract

Oxidation of the complex naphthol derivative (Ia) by iron(III) chloride in ethanol gives the 1,2-naphthoquinone derivative (III) through loss of the aromatic methyl group. There is an intermediate stage which is reached quickly and appears to give a mixture of products including the stereoisomeric spirans (XIX). Though there are some differences, a general similarity is pointed out between these reactions and oxidations to quinones and spirans in the tocopherol series. No specific precursor was identified.