Oxidation of <i>p</i>-Aminophenols and Formal Radical Cyclization onto Benzene Rings:  Formation of Benzo-Fused Nitrogen Heterocycles

Abstract

p-Iodophenol and its O-MOM-protected ether can be converted into iodoamines 2. These give cross-conjugated ketones 3 on oxidation with hypervalent iodides in the presence of methanol, and the ketones undergo radical cyclization. Exposure of the products to acid or sequential treatment with a Grignard reagent and acid effects rearomatization to produce benzo-fused nitrogen heterocycles 4.