2-Hydrazinyltetrahydropyrimido [4, 5-b] quinolin-4(3H)-one (3) was prepared by desulfurization reaction of S- and N-dimethyl derivatives 2 with hydrazine hydrate. Reactions of (3) with malonitrile, carbondisulfide, potassium thiocyanate, phthalic anhydride and aromatic aldehydes afforded 3, 5-di aminopyrazolopyrimido [4, 5-b] quinoline (4), triazolotetrahydropyrimido [4, 5-b] quinoline (5), aminotriazolopyrimido [4, 5-b] quinoline (6), aminophthalimidopyrimido [4, 5-b] quinoline (7) and N-arylidene hydrazinepyrimido [4, 5-b] quinoline 8a-d, respectively. Furthermore, 8a-d reacted with mercaptoacetic acid gave the thiazolidinonepyrimido [4, 5-b] quinoline 9a-d, which afforded the thiazolotriazolopyrimido [4, 5-b] quinolinone 10a-d upon treatment with ethanolic potassium hydroxide. The newly synthesized compounds were characterized by elemental analyses, IR, $^1H$-NMR, $^{13}C$-NMR and mass spectrometer. The investigated compounds were screened for their cytotoxicity. Compounds 4, 6 and 5 exhibited potent antitumor activity.