Structural modifications to the benz [g] isoquinoline skeleton of N-substituted benz [g] isoquinoline-3, 5, 10 (2H)-triones were envisaged in order to make future SAR studies possible for this type of bioactive compounds. Several N-substituted benz [g] isoquinoline-3, 5, 10 (2H)-triones were converted to novel 2, 4-substituted benz [g] isoquinoline-3, 5, 10 (2H)-triones, new tetracyclic 1, 2, 3, 5-substituted naphtho [3, 2, 1-de] isoquinoline-4, 7- ...