Addition of an N-substituted indole without any substitution in the 2 and 3 positions to 1,4-naphtoquinone leads to the expected, 2-(3-indolyl)-1,4-naphtoquinone. The latter reacts with some dienophiles via a Diels - Alder reaction and gives new N-substituted naphto-[2,3-C]-carbazole-5-13-quinones.