Compounds of the structure of <benz-[f]-indole>-4,9-dione are known to have an antibacterial activity against Gram-positive bacteria. New kinds of 2-amino-<benz-[f]-indole)-4,9-diones are prepared via intramolecular cyclization. 2-Chloro-3-($alpha$-cyano-$alpha$-ethoxycarbonyl-niethyl)-1,4-naphthoquino ne was reacted with some alkylamines(methylamine, ethylamine, ethanolarnine, isopropylamine, cyclohexylamine, benzylamine) to yield 2-amino-3-ethoxycarbonyl-N-alkyl-<benz-[f]-indole>4,9-diones.