Design and synthesis of angucyclinone AB-pyrido[2,3-d] pyrimidine analogues

The preparation of two pyrimido[4,5-c]isoquinoline-7,10-quinones from acylhydroquinones and 1,3-dimethyl-5-aminouracil and their cycloadditions with 1-trimethylsilyloxybutadiene and 1-dimethylamino-3-methyl-1-azabutadiene is described. The remarkable regiocontrol of these cycloadditions that yield stable 1:1 cycloadducts is discussed on the basis of steric interactions into the pyrimido[4,5-c]isoquinoline-7,10-quinones. The access to angucyclinone AB-pyridopyrimidine analogues from Diels–Alder adducts and preliminar evidences on their antitumour activities are also reported.