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Derivatives of the title ring system of type 10 were obtained in good yield by fusion of the intermediates 12. Attempt to cyclize the acetylamino derivative 9 under Bischler-Napieralski conditions failed because of the insufficient electronic density in the position 4 of the pyrazole ring created by the adjacent carbonyl moiety. The derivatives of the new ring system, assayed as anxiolytic agents, showed no significant activity.

New N-methyl and N-ethyl substitutions in the indazole nucleus are reported by reacting 3-(2-aminobenzamido)indazole and the appropriate trimethyl/triethyl orthobenzoate. Single crystal X-ray analysis confirms the N-ethylation position for the 3-(1-ethyl-1H-indazol-3-yl)-2-phenylquinazolin-4(3H)-one derivative 3f. Compounds 11a-d and 3a-d were tested to evaluate their antimicrobial, their antiproliferative activity and their COX inhibitory activities showing scarce or moderately antiproliferative activity and some inhibitory activity against COX-1 and COX-2.

A series of substituted derivatives containing the 1,4-benzodioxine or pyrrole nucleus are described. All the newly synthesized compounds were examined for their in vitro and in vivo anti-inflammatory activity. Several derivatives, including (S)-2, 14 and 17, showed more anti-inflammatory activity in vivo in these assays (rat paw oedema induced by carrageenan) than the known classical anti-inflammatory agent ibuprofen, whereas other compounds like 1 were equipotent to ibuprofen. Compound 17 was the most outstanding derivative because of its remarkable in vivo anti-inflammatory activity. In this paper, we examine and discuss the structure-activity relationships and anti-inflammatory activities of these compounds.

The diazonium salt derived from 4-amino-N,1,3-trimethyl-N-(3-methyl-1-phenyl-1H-pyrazol-5-yl)-1H-pyrazole-5-carboxamide (14) was reacted with a mixture of CuSO4 and NaCl, with ascorbic acid as an initiator to afford the planar derivative 4,6-dihydro-1,4,6,8-tetramethyl-3-phenyldipyrazolo[3,4-b:4′,3′-d]pyridin-5(3H)-one (16) and its unexpected isomer 4,6-dihydro-3,4,6,8-tetramethyl-1-phenyldipyrazolo[4,3-b:4′,3′-d]pyridin-5(1H)-one (17), as well as the epimers (3S,4S)- (or (3S,4R)-) and (3S,4R)- (or (3S,4S)-) 4-chloro-2,4-dihydro-1′,3′,5,5′-tetramethyl-2-phenylspiro[pyrazole-3,4′(1′H)-pyrrolo[3,4-c]pyrazol]-6′(5′H)-one (18a and b, respectively). Epimers 18a and b were converted under basic conditions to 4′-chloro-N,1,3,3′-tetramethyl-1′-phenyl-[4,5′-bi-1H-pyrazole]-5-carboxamide (19). The structures of isomers 16 and 17 determined by single-crystal X-ray analysis are also reported. Linear dichroism (LD) measurements for the above isomers suggest that 17 intercalates into DNA, and 17 exhibited antiproliferation activity against human NCI-H460 pulmonary carcinoma cells.

Several new 4-(3,3-dimethyltriazeno)-5-benzamidopyrazole derivatives were prepared by reacting 4-diazo-5-benzamidopyrazole derivatives with dimethylamine. The compounds were tested at 10 microM for their vitro antileukemic activity against K562 (Human chronic myelogenous leukemia) and Raji (human Burkitt limphoma ) cell lines. Dacarbazine and methotrexate were used for comparative purpose. The 3-methyl-4-(3,3-dimethyltriazeno)-5-(substituted benzamido)pyrazoles, bearing the pyrazole nucleus free at 1 position, resulted more active than the 1-(substituted phenyl)-3-methyl-4-(3,3-dimethyltriazeno)-5-benzamidopyrazoles. Dacarbazine at 10 microM showed no activity in the above tests. The observed difference among Dacarbazine and the active 4-triazenopyrazoles migth be explained admiting that these last compounds, differently by Dacarbazine, did not follow a mechanism of action based on the cytochrome P-450 induced demethylation. The most active compound 2d showed growth inhibition values of 97.8 and 99.4% against K562 and Raji cell lines respectively. Methotrexate inhibition values at 0.2 microM against the above cell lines were 86.7 and 75.1% respectively.

In order to study the influence of 3-substitution on the cytotoxic activity of 2-styrylquinazolinones, new 6-chloro-2-styryl-3-(heteroaryl)-4(3H)-quinazolinones were synthesized by refluxing equimolar amounts of 6-chloro-2-methyl-3-(heteroaryl)-4(3H)-quinazolinones and benzaldehyde in glacial acetic acid. At 1 microg ml(-1) concentration, almost all 2-styrylquinazolinones showed some cytotoxic activity against the L1210 and K562 leukemia cell lines. However, only 6-chloro-2-styryl-3-(pyrimidin-2yl)-4(3H)-quinazolinone inhibited the growth of these cells by over 50%. This last compound was also the only member of the series that inhibited tubulin polymerization, with an IC(50) value of 5.8 versus 3.2 microM for colchicine. It was also examined for effects on the growth of human MCF7 breast carcinoma cells and Burkitt lymphoma CA46 cells, which had IC(50) values of 0.34 and 1.0 microM, respectively. At 10 microM 6-chloro-2-styryl-3-(pyrimidin-2yl)-4(3H)-quinazolinone induced G2/M arrest (66%) in Burkitt cells, with a mitotic index of 20%. At 3.4 microM, it caused disruption of the cellular microtubule system of the MCF7 cells. Both these cellular effects are consistent with its mechanism of action resulting from its inhibitory effect on tubulin assembly.

A series of new 3-amino-N-phenyl-1H-indazole-1-carboxamides 10 have been prepared from commercially available phenyl isocyanate precursors 8 and 3-aminoindazole 9. Some of the synthesized compounds were evaluated for their in vitro antineoplastic activity against 60 human cell lines derived from seven clinically isolated cancer types (lung, colon, melanoma, renal, ovarian, brain, and leukemia) according to the NCI standard protocol. The test results indicated that 3-amino-1H-indazole-1-carboxamides 10 were endowed with an interesting antiproliferative activity. The most active compounds of this series, 10d,e, were able to inhibit cell growth of many neoplastic cell lines at concentrations lower than 1 μM (0.0153 μM in SR leukemia) causing a block in G0–G1 phase of cell cycle. Analysis of pRb expression showed that these two compounds increased the ratio between underphosphorylated pRb and total pRb. The X-ray structure of 10w, confirmed the 3-amino-N-phenyl-1H-indazole-1-carboxamide structure of compounds 10.

The title compounds were easily synthesized by reacting the 4-aminopyrazole hydrochloride 2 and the substituted 2-nitrobenzoyl chlorides 3a-d. The obtained 2-nitrobenzamides 4a-d were methylated and then reduced to give the corresponding amines 6a-d. These were hydrolyzed then directly converted into 4,10-dihydro-1H-pyrazolo[3,4-c][1,5]benzodiazocine-5,11-diones 1a-d by the action of SOCl2 in benzene. These were tested for their COX inhibitory activity, showing an inhibitory profile against both COX-1 and COX-2, being slightly more selective against COX-2 with a percentage of inhibition, at the concentration of 10 μM, in the range 42.0 – 55.0.

The diazonium tetrafluoroborate 11 obtained from 2-amino-N-methyl-N-(1-phenyl-3- methylpyrazol-5-yl)benzamide was transformed in dry acetonitrile via an ionic or radical pathway. Differences were observed with respect to ionic or radical transformations in aqueous media of the analogous diazonium hydrogen sulfate 1 derived from the same amine. In acetonitrile solution, the ionic pathway was characterized by an increased yield of 1,4-dimethyl- 3-phenyl-pyrazolo(3,4-c)isoquinolin-5-one 4 and by the formation of its isomer, the new derivative 7,9-dimethyldibenzo(e,g)pyrazolo(1,5-a)(1,3)diazocin-10(9H)-one 12. When the reaction followed a radical pathway, the pyrazolo(3,4-c)isoquinoline derivative 4 and N-methyl- 2-(1-phenyl-3-methylpyrazol-5-yl)benzamide 17, the latter due to a 1,4-pyrazolyl transfer process, were isolated in low yields. Decomposition of the solid diazonium tetrafluoroborate at its melting point gave compounds 4, 12 and the N-(1-phenyl-3-methylpyrazol-5-yl)-2- fluorobenzamide 17. The crystal structure of compound 12 was also determined.