Synthesis and biological activity of some 4-amino-3-cinnolinecarboxylic acid derivatives. Part 5: Pyrimido[5,4-c]cinnolines and triazepino[7,6-c]cinnoline.

A series of substituted 3-aminopyrimido[5,4-c]cinnolines 3, 7 was prepared. 6,7-Substituted 4-amino-3-cinnolinecarboxylic acid 1 were condensed with acetic anhydride to give the respective 1,3-oxazino[5,4-c]cinnolines 2. The obtained derivatives reacted with hydrazines and gave 3-aminopyrimido[5,4-c]cinnolines. Reaction of the esters 5 with hydrazines produced hydrazides 6, which upon treatment with N,N-dimethylformamide dimethyl acetal gave 3-aminopyrimido[5,4-c]cinnolines 7. Treatment of 6b with bromocyan produced 2-amino-3,4-dihydro-3,10-dimethyl-5 H-1,3,4-triazepino[7,6-c]cinnolin-5-on (8b). Some of the synthesized compounds were screened for their effect on the CNS.