Oxidative free radical reactions between 2-amino-1,4-naphthoquinones and carbonyl compounds

The manganese(III) initiated oxidative free radical reaction provides a novel method for the synthesis of benzo[f]indole-4,9-diones from 2-amino-1,4-naphthoquinones and carbonyl compounds. The regioselectivity of this reaction was also studied with unsymmetrical ketones from which both isomeric indoles 10 and 11 were formed. With α-halo, α-phenoxy and α-methanesulfonyl ketones, in most cases, this reaction gave high regioselectivity. With 2-alkyl substituted-1,3-dione 14, indole 11 was obtained as the only product.