Synthesis, structures and biological activity of some 4-amino-3-cinnoline-carboxylic acid derivatives. Part 3: 1,3-Oxazino[5,4-c]cinnolines and pyrimido[5,4-c]cinnolines.

6,7,8-Substituted 4-amino-3-cinnolinecarboxylic acids 1 were condensed with acid anhydrides to corresponding 1,3-oxazino[5,4-c]cinnolines 2. The reactions of 1,3-oxazino[5,4-c]cinnolines 2 with amines, hydrazine, hydroxylamine, alanine ethyl ester provided pyrimido[5,4-c]cinnolines 3, 4. Selected 3-substituted 2-methylpyrimido[5,4-c]cinnolin-4(3 H)-ones have been screened for CNS activity.