Cerium salts in the oxidative free radical reactions between 2-amino-1,4-naphthoquinones and β-dicarbonyl compounds

The oxidative free radical reactions between 2-amino-1,4-naphthoquinones and β-dicarbonyl compounds mediated by cerium(IV) salts are described. In contrast to those mediated by manganese(III) acetate, the cerium(IV) mediated free radical reaction provides a novel method for the synthesis of benzo[f]indole-4,9-diones exclusively. This high selectivity is due to the strong oxaphilicity of the cerium salts.