Synthesis and binding studies of 1-arylpyrazolo[4,5-c]- and 2-arylpyrazolo[4,3-c]quinolin-4-ones. I

The syntheses of some 2-aryl-3-methyl-4,5-dihydro-2H-pyrazolo [4,3-c] quinolin-4-ones and 1-aryl-3-methyl-4,5-dihydro-1H-pyrazolo-[4,5-c] quinolin-4-ones are reported. Some of the latter have shown a high activity in displacing specific [3H]-flunitrazepam binding from bovine brain membranes.     

Pyrazolo[4,5-c]quinolines. 3. Synthesis, receptor binding, and 13C NMR study

Some 1-aryl-3-methylpyrazolo[4,5-c]quinolin-4-ones, were prepared and tested for their ability to displace specific [3H]flunitrazepam binding from bovine brain membranes. The 1-meta-aryl derivatives were the compounds that bound with the highest affinity within this class. Our 13C NMR study suggested a correlation between the binding affinity and the chemical shift value of a carbon atom of the tricyclic system.     

Synthesis and antimicrobial activity of novel pyrazolo[3,4-b]quinoline derivatives

New pyrazolo[3,4-b]quinoline derivatives have been prepared by cyclization of the intermediate 2-chloroquinoline-3-carbonitrile 7, namely 3-amino-1H-pyrazolo[3,4-b]quinoline 8a, 3-amino-1-phenyl/(p-substituted)phenyl/-1H-pyrazolo[3,4-b]-quinoline 8b-f. Furthermore, 3-[(3-aryl-4-oxothiazolidin-2-ylidene)amino]-1H-pyrazolo[3,4-b]quinolines 11a,b; 3-[(3-aryl-4-oxothiazin-2-ylidene)amino]-1H-pyrazolo[3,4-b]quinolines 12a,b and 3-(2-aryl-4-oxothiazolidin-3-yl)-1H-pyrazolo[3,4-b]quinolines 13a,b were synthesized. The antimicrobial activity was evaluated for most of the prepared compounds.     

1,3-Diarylpyrazolo[4,5-c]- and -[5,4-c]quinolin-4-ones. 4. Synthesis and specific inhibition of benzodiazepine receptor binding

A series of 1,3-diarylpyrazolo[4,5-c]- and -[5,4-c]quinolin-4-ones were prepared and tested for their ability to displace [3H]flunitrazepam from bovine brain membranes. While the 1,3-diarylpyrazolo[4,5-c]quinoline derivatives showed affinity for the receptor site, their [5,4-c] isomers were devoid of binding activity.     

Synthesis of 11-aryl-5H-imidazo[2,1-c][1,4]benzodiazepines and their benzodiazepine and A1 adenosine binding activity.

In the context of a research program aimed at elucidating the properties of the 5H-imidazo[2,1-c][1.4]benzodiazepine system, a series of 11-aryl-5H-imidazo[2,1-c][1,4]benzodiazepines (3a-i) and their 10,11-dihydro-derivatives (4a-i) has been synthesized. The synthetic strategy includes the preparation of the aryl-[1-(2-nitrobenzyl)-1H-imidazol-2-yl]methanones (5a-i) followed by their reduction and subsequent cyclization. Affinities of compounds 3a-i and 4a-i for central benzodiazepine as well as for adenosine A1-receptors were determined by radioligand binding assays. Among the unsaturated analogues, the highest activity at both receptors is displayed by 1H-(2-thienyl) derivative 3e. The hydrogenated analogues 4a-i do not exhibit considerable binding affinity either for central benzodiazepine or for adenosine A1-receptors.     

Synthesis of 1,5-diaryl-3-methyl-1H-pyrazolo[4,5-c]isoquinolines and studies of binding to specific peripheral benzodiazepine binding sites

Some 1,5-diaryl-3-methyl-1H-pyrazolo[4,5-c]isoquinolines were synthesized and tested for their ability to displace [3H]clonazepam or [3H]Ro 5-4864 from their specific binding on the central and peripheral benzodiazepine receptors. None of the tested compounds showed any activity as central binding inhibitors, while most of them were specific as peripheral binding inhibitors, although they were not very potent.     

1H-imidazo[4,5-c]quinolin-4-amines: novel non-xanthine adenosine antagonists

On the basis of a model we recently developed for the antagonist binding site of the adenosine A1 receptor (J. Med. Chem. 1990, 33, 1708-1713), it was predicted that 1H-imidazo[4,5-c]quinolin-4-amines would be antagonists of the A1 receptor. Furthermore, it was expected that certain hydrophobic substitutions at the 2- and 4-positions would enhance affinity. Here, we report on the synthesis and the adenosine A1 and A2 receptor affinity of substituted 1H-imidazo[4,5-c]quinolin-4-amines. Some of these compounds have nanomolar affinity for the A1 receptor. The structure-activity relationships (SAR) of these compounds are discussed in relation to SAR for other adenosine receptor ligands. The 1H-imidazo[4,5-c]quinolin-4-amines constitute a novel class of non-xanthine adenosine antagonists.     

Synthesis and adenosine receptor affinity of a series of pyrazolo[3,4-d]pyrimidine analogues of 1-methylisoguanosine

Pyrazolo[3,4-d]pyrimidines are pyrazolo analogues of purines. They have been shown to be a general class of compounds which exhibit A1 adenosine receptor affinity. Two series of pyrazolo[3,4-d]pyrimidine analogues of 1-methylisoguanosine have been synthesized. The first involved substitution of the N1-position while the second involved substitution of the N5-position. Both alkyl and aryl substituents were examined. All compounds were tested for A1 adenosine receptor affinity by using a (R)-[3H]-N6-(phenylisopropyl)adenosine binding assay. The 3-chlorophenyl group showed the greatest activity in the N1-position and the butyl group produced the greatest activity in the N5-position. Combination of the best substituent in each of these positions enhanced the overall activity. The most potent compound was 4-amino-5-N-butyl-1-(3-chlorophenyl)-1H-pyrazolo[3,4-d]pyrimidin-6(5H)- one with an IC50 of 6.4 x 10(-6) M. Selectivity at the receptor subclasses was examined by performing an A2 adenosine receptor affinity assay with [3H]CGS 21680. This series of compounds were slightly less potent at A2 receptors. 4-Amino-5-N-butyl-1-(3-chlorophenyl-1H-pyrazolo[3,4-d]pyrimidin-6(5H)-one was the most potent compound with an IC50 of 19.2 x 10(-6) M.     

Synthesis of 2,3,5,6-tetrahydro-3H-imidazo[2,1-b] [1,3,5]benzotriazepines and their oxidative ring contraction into 1-(4,5-dihydro-1H-imidazol-2-yl)-1H-benzimidazoles

Syntheses of novel 5-aryl-2,3,5,6-tetrahydro-3H-imidazo[2,1-b] [1,3,5]benzotriazepine derivatives 3a-g were performed by reacting 2-(2-aminoarylimino)imidazolidines 1a-b with corresponding aryl aldehydes. The compounds 3 incorporating aminal group upon treatment with 2,3-dichloro-5,6-dicyano-1,2-benzoqinone (DDQ) underwent the oxidative ring contraction to give 1-(4,5-dihydro-1H-imidazol-2-yl)-2-aryl-benzimidazoles 4a-g. Reactions of the compounds 1a-c with carbonyldiimidazole (CDI) afforded novel 2,3,5,6-tetrahydro-1H-imidazo[2,1-b] [1,3,5]benzotriazepin-5-ones 5a-c which when heated in boiling methanol gave the corresponding 1-(4,5-dihydro-1H-imidazol-2-yl)-1,3-dihydro-2H-benzimidazol-2-ones 6a-c. Radioligand binding studies using rat central imidazoline I2 receptors and alpha2-adrenoceptors demonstrated that benzimidazoles 4a-g display a low affinity (microM) for these receptors while benzimidazol-2-ones 6a-b elicited a moderate affinity for I2 receptor with Ki values of 490 and 220 nM, respectively.     

Analogs of the anorexic mazindol.

Mazindol, 5-(p-chlorophenyl)-2,5-dihydro-3H-imidazo[2,1-a]isoindol-5-ol, has been shown to be an effective anorexic. To explore the structure-activity relationships, several 1-ethyl-3-substituted-4-aryl-4-hydroxyindeno[1,2-c]pyrazoles were prepared and subjected to various animal screens. The 1-ethyl-3-tert-butyl-4-aryl-4-hydroxyindeno[1,2-c]pyrazoles are capable of significantly depressing forced and spontaneous motor activity in mice but have low LD50's. Two of these compounds were tested in an Ehrlich ascites tumor screen. The 1-ethyl-3-phenyl-4-aryl-4-hydroxyindeno[1,2-c]pyrazoles depressed forced and spontaneous motor activity at low doses and were relatively nontoxic.     

Studies on annelated 1,4-benzothiazines and 1,5-benzothiazepines. II. Synthesis of new series of 1- or 2-substituted 4H-s-triazolo[3,4-c]-1,4-benzothiazines and related compounds with potential CNS activity

New series of 1- or 2-substituted 4H-s-triazolo[3,4-c]-1,4-benzothiazines have been prepared. The 1-substituted products were obtained starting from 3-hydrazino-2H-1,4-benzothiazine derivatives (III) by treatment with chloroacethyl chloride followed by cyclization of the resulting chloroacethylderivatives into the chloromethyltriazolobenzothiazines (IV a-e), which were then reacted with the appropriate amines to give the desired compounds (V a-n). Other 1-substituted compounds were prepared by ring closure of (III) with cyanogen bromide, affording 1-amino-4H-s-triazolo [3,4-c]-1,4-benzothiazines (XI a-e). The 2-substituted compounds (VIII) were prepared from 2,4-dihydro-1H-s-triazolo [3,4-c]-1,4-benzothiazin-1-ones (VII), synthesized from (I) by reaction with ethyl carbazate. The aminoalkyl side chain was introduced into (VII) in two steps: first by treatment with 1-bromo-3-chloropropane, then by refluxing the resulting product with the appropriate amine. Some 4H-tetrazolo[5,1-c]-1,4-benzothiazines (XII) were also synthesized from (III). Preliminary pharmacological data on the CNS activity of the synthesized tricyclic compounds are reported.     

Benzimidazolyl quinolinyl mercaptotriazoles as potential antimicrobial and antiviral agents

Condensation of ethylaceto acetate (EAA) with resorcinol in concentrated H2SO4 afforded 7-hydroxy-4-methyl coumarin (1), which on reaction with thiosemicarbazide in anhydrous pyridine yielded 7-hydroxy-4-methyl-quinolinyl [1,5-c]-mercaptotriazole (2). Reaction of 2 with formaldehyde solution and amino acid in ethanol yielded 7-hydroxy-4-methyl-8-(N-methyl-aminoacid)-quinolinyl [1,5-c]-2'-mercaptotriazole (3a-e). Interaction of 3 with o-phenylenediamine in pyridine yielded 7-hydroxy-4-methyl-8-(aminobenzimidazolyl)-quinolinyl [1,5-c]-2'-mercaptotriazole derivatives (4a-e). The latter compounds were evaluated for their antiviral and antimicrobial activities.     

Research on agents with antineoplastic activity. LXIII. Anthramycin and analogous compounds. X. Synthesis of 11-phenyl-5H-pyrrolo[2,1-c] [1,4] benzodiazepine derivatives

Reaction between arolychlorides and 1-(2-aminobenzyl)-2-cyanopyrrole afforded the corresponding aroylamides, which were transformed by intramolecular cyclization into 11-aryl-3-cyano-5H-pyrrolo[2,1-c] [1,4] benzodiazepines. Hydrolysis of cyanoderivatives furnished the corresponding amides or acids depending on the reaction conditions. Decarboxylation and reduction of some derivatives to afford 11-aryl-5H-pyrrolo[2,1-c] [1,4] benzodiazepines and 11-aryl-3-cyano-10,11-dihydro-5H-pyrrolo[2,1-c] [1,4] benzodiazepines are described.     

Synthesis and inotropic activity of pyrazolo[4,3-c]pyridine-4-ones and related compounds.

Two series of 3,6-dimethyl-1-phenyl-1H-pyrazolo[4,3-c] pyridine-4-ones (5-9) and 3,6-dimethyl-1-phenyl-1H-pyrazolo[4,3-c] pyridine-4-thiones (11-13) were prepared from dehydroacetic acid as starting material and evaluated for positive inotropic activity in vitro. Moreover, the activity of the synthesized compounds was compared with that of mirlinone as a reference. Among these compounds, the positive inotropic activity of 8a, 11a, and 12 were approximately 1.24, 1.77, and 1.11 times more potent, respectively, than that of mirlinone.     

Tricyclic heteroaromatic systems. Synthesis and benzodiazepine binding activity of 1-substituted-3-methyl- and 3-phenylpyrazolo[4,5-c]quinolin-4-ones.

The synthesis and the benzodiazepine binding activity of some 3-methyl- and 3-phenylpyrazolo[4,5-c]quinolin-4-ones bearing a heterocyclic or a substituent which is different from an aryl moiety at position-1 are reported. Molecular modelling is used to correlate the binding affinity to the chemical features and to justify the reduced receptor affinities of the reported compounds with respect to that of CGS 8216 which is taken as the lead compound.     

Synthesis, antimicrobial, and antiviral activities of some new 5-sulphonamido-8-hydroxyquinoline derivatives

A series of fused pyranopyrazole and pyranoimidazole, namely 5-(3,6-diamino-4-aryl-5-carbonitrile-pyrano(2,3-c)pyrazol-2-yl)sulphonyl-8-hydroxyquinolines (5a-e), 5-(6-amino-4-aryl-5-carbonitrile-pyrano(2,3-c)pyrazol-3-yl)sulphonamido-8-hydroxyquinolines (6a-e), 5-(2-thioxo-4-aryl-5-carbonitrile-6-amino-pyrano(2,3-d)imidazol-2-yl)sulphonyl-8-hydroxyquinolines (10a-e), and 5-(2-oxo-4-aryl-5-carbonitrile-6-amino-pyrano(2,3-d)imidazol-2-yl) sulphonyl-8-hydroxyquinolines (11a-e), have been prepared via condensation of some arylidine malononitriles with 5-sulphonamido-8-hydroxyquinoline derivatives 3, 4, 8 and 9. All the synthesized compounds were screened for their antimicrobial activities, and most of the tested compounds showed potent inhibition growth activity towards Escherichia coli, Pseudomonas aeruginosa (Gramnegative bacteria). Furthermore, six selected compounds were tested for their antiviral activity against avian paramyxovirus type1 (APMV-1) and laryngotracheitis virus (LTV), and the results showed that a concentration range of 3-4 μg per mL of compounds 2, 3, and 4 showed marked viral inhibitory activity for APMV-1 of 5000 tissue culture infected dose fifty (TCID(50)) and LTV of 500 TCID(50) in Vero cell cultures based on their cytopathic effect. Chicken embryo experiments show that compounds 2, 3, and 4 possess high antiviral activity in vitro with an inhibitory concentration fifty (IC(50)) range of 3-4 μg per egg against avian APMV-1 and LTV and their toxic concentration fifty (CC(50)) of 200-300 μg per egg.     

Indeno[1,2-c]pyrazolone acetic acids as semirigid analogues of the nonsteroidal anti-inflammatory drugs

A series of 3-substituted indeno[1,2-c]pyrazol-4(1H)-one-2-acetic acids (3a-e) and 3-substituted indeno[1,2-c]pyrazol-4(1H)-one-1-acetic acids (4a-e) were synthesized as semirigid analogues of tolmetin (1). These compounds were evaluated for their anti-inflammatory action by investigating their ability to block arachidonic acid metabolism in vitro as well as the ability to block carrageenan-induced rat foot edema in vivo. No consistent pattern of biological activity was noted.     

Synthesis, central and peripheral benzodiazepine receptor affinity of pyrazole and pyrazole-containing polycyclic derivatives

A series of new pyrazole-condensed 6,5,5 tricyclic compounds were synthesized and tested to evaluate their binding affinities at both central (CBR) and peripheral (PBR) benzodiazepine receptors. Some 1-aryl-5-phenylpyrazole derivatives were also prepared and tested for comparison with their corresponding rigid tricyclic analogs. Among the newly synthesized 1-aryl-1,4-dihydro-indeno[1,2-c]pyrazoles bearing both an ethoxycarbonyl group at position 3 and a carbonyl function at the position 4, compound 4b emerged as a new potent (IC(50) = 26.4 nM) and selective CBR ligand. The 4-oxo-1-aryl-1,4-dihydro-indeno[1,2-c]pyrazole diethylamide derivative 14a was instead identified as a relatively potent (IC(50) = 124 nM) but highly selective PBR ligand.     

New antiinflammatory agents. 2. 5-Phenyl-3H-imidazo[4,5-c][1,8]naphthyridin-4(5H)-ones: a new class of nonsteroidal antiinflammatory agents with potent activity like glucocorticoids.

We previously described new antiinflammatory agents, 4-hydroxy-2-oxo-1-phenyl-1H-1,8-naphthyridine-3-carboxamides 1. Further modification of the compounds bearing 1-phenyl-1,8-naphthyridin-2-one as a mother skeleton led to 5-phenylimidazo[4,5-c][1,8]naphthyridin-4(5H)-one derivatives 2 and 3. Regioselective synthesis of these compounds bearing a substituent at the 1- or 3-position was conducted according to the method shown in Schemes I and II. In this series of compounds, antiinflammatory activities were greatly influenced by the position and nature of substituents on imidazole. 3-Alkyl or 3-benzyl substitution result in the potent activity, but 1-substitution did not. Minor modification of the benzyl group reduced or eliminated the activity. Detailed examination of structure-activity relationships led to 3-benzyl-5-phenyl-3H-imidazo[4,5-c][1,8]naphthyridin-4(5H)-one (22), which exhibited potent oral antiinflammatory activities in carrageenan-, zymosan-, and reversed passive Arthus reaction-induced rat paw edemas (ED40 = 5.3, 0.37 mg/kg, ED50 = 0.47 mg/kg, respectively). This broad activity of 22 was like that of glucocorticoids. Compound 22 did not affect activities of CO and 5-LO enzymes and receptor binding of various ligands. As one of the mechanisms of action, induction of release of glucocorticoids was postulated. These results suggest that 22 represents a novel class of antiinflammatory agents.     

Synthesis and biological evaluation of 1-aryl-4,5-dihydro-1H-pyrazolo[3,4-d]pyrimidin-4-one inhibitors of cyclin-dependent kinases

Using a high-throughput screening strategy, a series of 1-aryl-4,5-dihydro-1H-pyrazolo[3,4-d]pyrimidin-4-ones was identified that inhibit the cyclin-dependent kinase (CDK) 4/cyclin D1 complex-mediated phosphorylation of a protein substrate with IC(50)s in the low micromolar range. On the basis of preliminary structure-activity relationships (SAR), a model was proposed in which these inhibitors occupy the ATP-binding site of the enzyme, forming critical hydrogen bonds to the same residue (Val96) to which the amino group in ATP is presumed to bind. X-ray diffraction studies on a later derivative bound to CDK2 support this binding mode. Iterative cycles of synthesis and screening lead to a novel series of potent, CDK2-selective 6-(arylmethyl)pyrazolopyrimidinones. Placement of a hydrogen-bond donor in the meta-position on the 6-arylmethyl group resulted in approximately 100-fold increases in CDK4 affinity, giving ligands that were equipotent inhibitors of CDK4 and CDK2. These compounds exhibit antiproliferative effects in the NCI HCT116 and other cell lines. The potency of these antiproliferative effects is enhanced in anilide derivatives and translates into tumor growth inhibition in a mouse xenograft model.