Reaction of 1,2-dihydro-2-thioxopteridin-4(3H)-one, 6,7-dimethyl-1,2-dihydro-2-thioxopteridin-4(3H)-one and 6,7-diphenyl-1,2-dihydro-2-thioxopteridin- 4(3H)-one with hydrazonoyl halides affords the title compounds in good yields.

A simple synthetic strategy is described for synthesis of 3-arylazo-2-methyl-7-phenylpyrimido [1,2-b][1,2,4]triazepine-4,9-diones 4a-j. The acid dissociation constants were determined for the series prepared and were correlated by a Hammett-type equation using enhanced substituent constants. The results of such correlation together with the spectral data, including 15 N isotopic labelling, indicated that the studied compounds exist predominantly in the hydrazone tautomeric form.

A new series of 3-(1,3-disubstituted-1H-pyrazole-4-carbonyl)-1,7-diphenyl-[1,2,4]triazolo[4,3-a]pyrimidin-5(1H)-ones 4 was prepared by reaction of the enaminone 2 with hydrazonoyl halides 3. The preliminary screening for antitumor activity of the synthesized compounds was carried out against Ehrlich Ascites Carcinoma tumor cells. The results revealed that the studied compounds 4 have low or no antitumor activity towards EAC tumor cells.

3‐Acetyl‐4‐benzoyl‐1,5‐diphenylpyrazole reacts with DMF‐DMA to give the novel enaminone 2. The reaction of the latter with various hydrazonoyl halides afforded regioselectively the respective substituted (3‐pyrazolyl)(4‐pyrazolyl)ketones 4 in good over all yield. The preliminary screening for the antitumor activity of the synthesized compounds 2 and 4a, 4b, 4c, 4d, 4e, 4f, 4g against human breast cancer cell line (MCF‐7) revealed that both compounds 2 and 4b have high‐antitumor activity. SAR is discussed. J. Heterocyclic Chem., 46, 548 (2009).

in Wiley InterScience (www.interscience.wiley.com).3-Acetyl-4-benzoyl-1,5-diphenylpyrazole reacts with DMF-DMA to give the novel enaminone 2. The reaction of the latter with various hydrazonoyl halides afforded regioselectively the respective substituted (3-pyrazolyl)(4-pyrazolyl)ketones 4 in good over all yield. The preliminary screening for the antitumor activity of the synthesized compounds 2 and 4a-g against human breast cancer cell line (MCF-7) revealed that both compounds 2 and 4b have high-antitumor activity. SAR is discussed.