2-(Dimethylaminomethyl)-tetrahydroisoxazolopyridobenzazepine derivatives. Synthesis of a new 5-HT(2C) antagonist with potential anxiolytic properties

Following the program started at Johnson & Johnson Pharmaceutical Research & Development searching for 5-HT_2A/2C antagonists, we now report on the synthesis of 2-(dimethylaminomethyl)-2,3,3a,8-tetrahydroisoxazolo[3,2-a]pyrido[3,4-c]-[2]benzazepine and 2-(dimethylaminomethyl)-2,3,3a,8-tetrahydroisoxazolo[3,2-a]pyrido[3,2-c]-[2]benzazepine. A new method for the synthesis of pyridobenzazepines is described as well. The affinities for several receptors as well as the mCPP antagonistic activity of the compounds synthesised are described.     

Synthesis and antiproliferative evaluation of certain indolo[3,2-c]quinoline derivatives

The present report describes the synthesis and antiproliferative evaluation of certain indolo[3,2-c]quinoline derivatives. For the C₆ anilino-substituted derivatives, (11H-indolo[3,2-c]quinolin-6-yl)phenylamine (6a) was inactive. Structural optimization of 6a by the introduction of a hydroxyl group at the anilino-moiety resulted in the enhancement of antiproliferative activity in which the activity decreased in an order of para-OH, 7a > meta-OH, 8a > ortho-OH, 9a. For the C₆ alkylamino-substituted derivatives, 11a, 12a, 13a, 14a, and 15a exhibited comparable antiproliferative activities against all cancer cells tested and the skin Detroit 551 normal fibroblast cells. Three cancer cells, HeLa, A549, and SKHep, are very susceptible with IC₅₀ of less than 2.17 μM while PC-3 is relatively resistant to this group of indolo[3,2-c]quinolines. For the 2-phenylethylamino derivatives, compound 20a is active against the growth of HeLa with an IC₅₀ of 0.52 μM, but is less effective against the growth of Detroit 551 with an IC₅₀ of 19.32 μM. For the bis-indolo[3,2-c]quinolines, N,N-bis-[3-(11H-indolo[3,2-c]quinolin-6-yl)aminopropyl]amine hydrochloride (25) is more active than its N-methyl derivative 26 and the positive Doxorubicin. Mechanism studies indicated 25 can induce caspase-3 activation, γ-H2AX phosphorylation, cleavage of poly(ADP-ribose)polymerase and DNA fragmentation. These results provide evidence that DNA, topo I, and topo II are the primary targets of indolo[3,2-c]quinoline derivatives and that consequently inhibits proliferation and causes apoptosis in cancer cells.     

Synthesis of new 4-[2-(alkylamino)ethylthio]pyrrolo[1,2-a]quinoxaline and 5-[2-(alkylamino)ethylthio]pyrrolo[1,2-a]thieno[3,2-e]pyrazine derivatives,as potential bacterial multidrug resistance pump inhibitors

The synthesis of new 4-[2-(alkylamino)ethylthio]pyrrolo[1,2-a]quinoxaline derivatives 1a-l is described in five or six steps starting from various substituted nitroanilines 2a-e. The bioisostere 5-[2-(alkylamino)ethylthio]pyrrolo[1,2-a]thieno[3,2-e]pyrazine 1m was also prepared. The new derivatives were evaluated as efflux pump inhibitors (EPIs) in a model targeting the NorA system of Staphylococcus aureus. The antibiotic susceptibility of two strains overproducing NorA, SA-1199B and SA-1, was determined alone and in combination with the neo-synthesised compounds by the agar diffusion method and MIC determination, in comparison with reserpine and omeprazole taken as reference EPIs. A preliminary structure-activity relationship study firstly allowed to clarify the influence of the substituents at positions 7 and/or 8 of the pyrrolo[1,2-a]quinoxaline nucleus. Methoxy substituted compounds, 1b and 1g, were more potent EPIs than the unsubstituted compounds (1a and 1f), followed by chlorinated derivatives (1c-d and 1h). Moreover, the replacement of the N,N-diethylamino group (compounds 1a-e) by a bioisostere such as pyrrolidine (compounds 1f-h) enhanced the EPI activity, in contrast with the replacement by a piperidine moiety (compounds 1i-k). Finally, the pyrrolo[1,2-a]thieno[3,2-e]pyrazine compound 1m exhibited a higher EPI activity than its pyrrolo[1,2-a]quinoxaline analogue 1a, opening the way to further pharmacomodulation.     

Synthesis and antibacterial properties of new N4-acetylated hexahydro-2,7-dioxopyrido[2,3-f]quinoxaline-8-carboxylic acids

Direct interaction between 7-chloro-1-cyclopropyl-6-fluoro-8-nitro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid and primary α-amino acids (exemplified by glycine, alanine, and l-valine) in aqueous ethanolic NaHCO₃ at 70–80°C for 24–72?h produced the respective N-(4-oxoquinolin-7-yl)-α-amino acids (6a–c). The latter derivatives underwent reductive lactamization upon treatment with Na₂S₂O₄ in aqueous ethanol to afford moderate yields of the corresponding pyrido[2,3-f]quinoxaline-8-carboxylic acids (8a–c). Acetylation of 8a–c using acetyl chloride afforded N₄-acetylated hexahydro-2,7-dioxopyrido[2,3-f]quinoxaline-8-carboxylic acids (9a–c). The structures, assigned to these new heterocyclic products, are supported by analytical and spectral data. The synthesized compounds (6a–c/9a–c) showed appreciable antibacterial activity as compared with ciprofloxacin.     

Synthesis,pharmacological studies and molecular modeling of some tetracyclic 1,3-diazepinium chlorides

Seven new 1,3-diazepinium chlorides exhibiting some structural similarities to the 1,4-benzodiazepines were synthesized. In a Hippocratic screen using mice, three of these salts, 3-methoxy-6-oxo-7,13-dihydro-6H-benzofuro[2,3-e]pyrido[1,2-a][1,3]diazepin-12-ium chloride (8a), 3-methoxy-9-methyl-6-oxo-7,13-dihydro-6H-benzofuro[2,3-e]pyrido[1,2-a][1,3]diazepin-12-ium chloride (8c) and 3-methoxy-11-methyl-6-oxo-7,13-dihydro-6H-benzofuro[2,3-e]pyrido[1,2-a][1,3]diazepin-12-ium chloride (8e) were examined for their effect on the central nervous system, and their activities compared to that of diazepam. On their own, salts 8a, 8c and 8e solicited no sedative effects on the behaviour of the animals. However, they elicited significant effects in combination with diazepam on diazepam-induced activities such as decreased motor activity, ataxia and loss of righting reflex. Compounds 8a and 8c were fitted into the pharmacophore/receptor model developed by Cook et al. with interaction at the L₁, H₁ and A₂ sites indicating that they are potential inverse agonists of the Bz receptor. The compounds displayed some affinity for the α1 isoform of the GABA_A/BzR (L_Di interaction) but are non-selective for α5 (no L₂ interaction). Results of binding affinity studies showed that compound 8a is mildly selective for the α1 receptor although not very potent (K_i = 746.5 nM). The significant potentiation of diazepam-induced ataxia and decreased motor activity by compounds 8a and 8c in the Hippocratic screen may be associated with α1 selectivity.     

A novel series of histamine H4 receptor antagonists based on the pyrido[3,2-d]pyrimidine scaffold: Comparison of hERG binding and target residence time with PF-3893787

In this work we describe the optimization of a lead compound based on the quinazoline template to give a new series of potent pyrido[3,2-d]pyrimidines as histamine H₄ receptor antagonists. The pyrido[3,2-d]pyrimidine ligands have significantly reduced hERG binding compared to clinical stage compound PF-3893787 while showing good affinities at the human and rodent histamine receptors. The receptor residence time of several of these new compounds was determined for the human H₄R and compared with JNJ7777120 and PF-3893787. The pyrido[3,2-d]pyrimidines showed residence times lower than JNJ7777120 but comparable to the residence time of PF-3893787. Overall, the pyrido[3,2-d]pyrimidines show an excellent in vitro profile that warrants their further investigation in relevant models of human disease.     

Synthesis of indole-tethered [1,3,4]thiadiazolo and [1,3,4]oxadiazolo[3,2-a]pyrimidin-5-one hybrids as anti-pancreatic cancer agents

New indole-tethered [1,3,4]thiadiazolo[3,2-a]pyrimidin-5-one (8a-j) and [1,3,4]oxadiazolo[3,2-a]pyrimidin-5-one hybrids (9a-e) were synthesized using [4+2] cycloaddition reactions of functionalized 1,3-diazabuta-1,3-dienes with indole-ketenes. All molecular hybrids were structurally characterized by spectroscopic techniques (IR, NMR, and HRMS) and screened for their anti-pancreatic cancer activity in vitro. The [1,3,4]oxadiazolo[3,2-a]pyrimidin-5-one hybrids (9a-e) showed stronger anti-pancreatic cancer activity than the [1,3,4]thiadiazolo[3,2-a]pyrimidin-5-one hybrids (8a-j) against the PANC-1 cell line. Compound 9d bearing an ortho-chlorophenyl moiety emerged as the most potent anti-pancreatic cancer agent with an IC₅₀ value of 7.7 ± 0.4 µM, much superior to the standard drug Gemcitabine (IC₅₀ > 500 µM). The discovery of these [1,3,4]thiadiazolo and [1,3,4]oxadiazolo[3,2-a]pyrimidin-5-one hybrids elicits their potentials as pursuable candidates for pancreatic cancer chemotherapy.     

In vitro cytotoxic potential of newly synthesized furo[3,2-<Emphasis Type="Italic">c</Emphasis>]pyran-4-one derivatives in cultured human lymphocytes

The in vitro cytotoxic potentials of Furo[3,2-c]pyran-4-one derivatives in human lymphocytes were investigated. Blood samples were obtained from six healthy donors, non-smoking volunteers, which were incubated and exposed to increasing concentrations (0.05, 0.1, 0.5, 1 and 2 mg/mL) of Furo[3,2-c]pyran-4-one derivatives which are methyl 2-methoxy-7-(4-methylbenzoyl)-6-(4-methylphenyl)-4-oxo-4H-furo[3,2-c]pyran-3-carboxylate (1a) and methyl 2-methoxy-7-(4-methoxybenzoyl)-6-(4-methoxyphenyl)-4-oxo-4H-furo[3,2-c]pyran-3-carboxylate (1b). Compounds 1a and 1b induced micronucleus, mitotic and replication indexes in human lymphocytes (1 and 2 mg/mL). The increases of micronucleus, mitotic and replication indexes show that compounds at high concentrations may become cytotoxic, genotoxic and carcinogenic.     

Synthesis of Pyrrolo[2′,3′:4,5]Furo[3,2-c]Pyridine-2-Carboxylic Acids

1H-Pyrrolo[2′,3′:4,5]furo[3,2-c]pyridine-2-carboxylic acid (6a) and its 1-methyl (6b) and 1-benzyl (6c) derivatives were synthesized. 3-(5-Methoxycarbonyl-4H-furo[3,2-b]-pyrrole-2-yl)propenoic acid (1) was converted to the corresponding azide 2, which in turn was cyclized to give 3 by heating in diphenylether. The pyridone 3 obtained was aromatized with phosphorus oxychloride, then reduced with zinc in acetic acid to give methyl 1H-pyrrolo[2′,3′:4,5]furo[3,2-c]pyridine-2-carboxylate (5), which by hydrolysis gave the corresponding carboxylic acid 6a.     

Synthesis of novel hetero ring fused pyridine derivatives; Their anticancer activity,CoMFA and CoMSIA studies

A series of novel furo[2,3-b]pyridine-2-carboxamide 4a–h/pyrido[3′,2′:4,5]furo[3,2-d] pyrimidin-4(3H)-one derivatives 5a–p were prepared from pyridin 2(1H) one 1 via selective O-alkylation with α-bromoethylester followed by cyclization, then reaction with different aliphatic primary amines to obtain 4 and further reaction with triethyl orthoacetate/triethyl orthoformate. Also prepared novel furo[2,3-b]pyridine-2-carbohydrazide Schiff’s bases 7a–h and pyrido [3′,2′:4,5]furo[3,2-d]pyrimidin-4(3H)-one derivatives 8a–h starting from furo[2,3-b]pyridine carboxylate derivatives 3 by reaction with hydrazine hydrate to form 6 and reaction with diverse substituted aldehydes and cyclization. Products 4a–h, 5a–p, 7a–h and 8a–h were screened against four human cancer cell lines (HeLa, COLO205, Hep G2 and MCF 7) and one normal cell line (HEK 293). Compounds 4e, 4f, 4g, 5h, 7c, 7d, 7e and 7f showed significant anticancer activity against all the cell lines at micro molar concentration and found to be non-toxic to normal cell line. Studies for HeLa, COLO205 and MCF-7 using CoMFA and CoMSIA. Models from 3D-QSAR provided a strong basis for future rational design of more active and selective HeLa, COLO205 and MCF-7 cell line inhibitors.     

Synthesis,anticancer assessment on human breast,liver and colon carcinoma cell lines and molecular modeling study using novel pyrazolo[4,3-c]pyridine derivatives

The key intermediate 3-aminopyrazolo[4,3-c]pyridine-4,6-dione (2) is considered as a precursor for some novel pyrazolo[4,3-c]pyridines 4a-c, arylhydrazopyrazolo[4,3-c]pyridines 8a-e, pyrazolo[4,5,1-ij][1,6]naphthyridines 11a-e and pyrido[4′,3′:3,4]pyrazolo[1,5-a]-pyrimidines 15a-d through Knovenegal condensation, coupling reaction and Michael addition. Some of the newly synthesized pyrazolo[4,3-c]pyridine derivatives were investigated for anticancer activity. The results of the cytotoxic activity revealed that compound 6b was the most active compound against the breast and liver carcinoma cell lines which gives IC₅₀ values of 1.937 and 3.695 µg/mL, respectively compared to reference drug (doxorubicin) with IC₅₀ values of 2.527 and 4.749 µg/ml, respectively. Moreover, compound 6c was potent compound against the colon carcinoma cell line which gives the value of IC₅₀ = 2.914 µg/ml compared to doxorubicin with IC₅₀ value of 3.641 µg/ml. Some selected of the novel synthesized compounds were docked inside the active site of ERK2 enzyme and were found display a suitable binding with the active site amino acids according to their bond lengths, angles and conformational energy.     

STRUCTURE AND BIOLOGICAL ACTIVITY OF A SERIES OF CONFORMATIONALLY RESTRICTED ANALOGUES OF GABA

—Microelectrophoretic methods were used to study the effects on spinal neurones of a series of conformationally restricted analogues of GABA, most of which are structurally related to musci-mol (3-hydroxy-5-aminomethylisoxazole). 3-Hydroxy-5-(l-aminoethyl)isoxazole and 3-hydroxy-5-(2-aminoethyl)isoxazole were GABA-like depressants comparable in effectiveness with GABA. The inhibitors of GABA uptake 4,5,6,7-tetrahydroisoxazolo[4,5-c]pyridin-3-ol and nipecotic acid (piperidine-3-carboxylic acid) reversibly enhanced the depressant action of GABA. 3-Hydroxy-5-dimethylaminomethly-isoxazole, 5,6,7,8-tetrahydro-4H-isoxazolo[4,5-d]azepm-3-ol, 4,5,6,7-tetrahydroisoxazolo[4,5-c]pyridin-3-ol, and nipecotic acid reversibly antagonized the postsynaptic action of glycine. A structure-activity correlation was made in an indirect attempt to elucidate some comformational requirements for interaction of GABA with its postsynaptic receptor and the binding site of its uptake system. The results seem to indicate that different conformations of GABA are required for these interactions.     

Potent and selective adenosine A2A receptor antagonists: 1,2,4-Triazolo[1,5-c]pyrimidines

Antagonism of the adenosine A_2a receptor offers great promise in the treatment of Parkinson’s disease. In the course of exploring pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine A_2A antagonists, which led to clinical candidate SCH 420814, we prepared 1,2,4-triazolo[1,5-c]pyrimidines with potent and selective (vs A₁) A_2a antagonist activity, including oral activity in the rat haloperidol-induced catalepsy model. Structure–activity relationships and plasma levels are described for this series.     

Discovery of novel methanone derivatives acting as antimycobacterial agents

A series of pyrazoline derivatives were synthesized and in vitro activity against Mycobacterium tuberculosis H37Rv was carried out. Among the synthesized compounds, compounds (4d) and (4f) 4-aminophenyl-3-(3,4-dimethoxyphenyl)-6,7-dimethoxy-2,3,3a,4-tetrahydroindeno[1,2-c]pyrazol-2-ylmethanone and 4-aminophenyl-6,7-dimethoxy-3-phenyl-2,3,3a,4-tetrahydroindeno[1,2-c]pyrazol-2-ylmethanone were found to be the most active agent against M. tuberculosis H37Rv with a minimum inhibitory concentration of 10?μg/mL.     

Identification of 4-(2-furanyl)pyrimidin-2-amines as Janus kinase 2 inhibitors

Janus kinases inhibitor is considered to have therapeutic potential for the treatment of oncology and immune-inflammatory diseases. Two series of 4-(2-benzofuranyl)pyrimidin-2-amine and 4-(4,5,6,7-tetrahydrofuro[3,2-c]pyridin-2-yl)pyrimidin-2-amine derivatives have been designed and synthesized. Primary SAR studies resulted in the discovery of a novel class of 4,5,6,7-tetrahydrofuro[3,2-c]pyridine based JAK2 inhibitors with higher potency (IC₅₀ of 0.7 nM) and selectivity (>30 fold) to JAK3 kinase than tofacitinib.     

Synthesis and biological evaluation of substituted 1,2,3-benzotriazines and pyrido[3,2-d]-1,2,3-triazines as inhibitors of vascular endothelial growth factor receptor-2

A novel series of substituted 1,2,3-benzotriazines and pyrido[3,2-d]-1,2,3-triazines were synthesized. The abilities of these compounds to inhibit the VEGFR-2 kinase activity and the proliferation of human microvascular endothelial cells (MVECs) were determined. 6-Methoxy-4-substituted-1,2,3-benzotriazines and 4-substituted-6-chloro-pyrido[3,2-d]-1,2,3-triazines have the abilities of inhibiting the VEGFR-2 kinase activity, but only the 4-substituted-6-chloro-pyrido[3,2-d]-1,2,3-triazines exhibit good growth inhibitory effects on MVECs. Compound 6-chloro-4-(3-trifluoromethylanilino)-pyrido[3,2-d][1,2,3]triazin (11d) is less half active than PTK787 to inhibit the VEGFR-2 kinase activity, but is more active than PTK787 to inhibit the growth of MVECs. The potential binding modes of 6d, 11d, and CTZ12 in complex with their putative intracellular target, VEGFR-2, were predicted using Surflex-Dock.     

Synthesis of novel selenium containing sulfa drugs and their antibacterial activities

Synthesis of 3-[4-(N-substituted sulfamoyl)phenyl]-3,4-dihydro-4-oxo-7,9-dimethylpyri-do[3′,2′:4,5]selenolo[3,2-d]pyrimidines,7-[4-(N-substituted sulfamoyl)phenyl]-7,8-dihydro-8-oxo-3,4-diphenylpyrimido[4′,5′:4,5]selenolo [2,3-c]pyridazines and 1-[4-(N-substituted sulfamoyl)phenyl]-1,11-dihydro 11-oxo-4-methylpyrimido[4′,5′:4,5]selenolo[2,3-b]quinolines is reported. 4-Amino-N-pyrimidine-2-ylbenzene sulfonamide (a), 4-amino-N-(2,6-dimethylpyrimidin-4-yl)benzene sulfonamide (b), N-[(4-aminophenyl)sulfonyl] acetamide (c) with N-ethoxymethyleneamino of selenolo pyridine, selenolo pyridazine and selenolo quinoline derivatives respectively were obtained starting from 1-amino-N ⁴-substituted sulfanilamides. Spectroscopic data (IR, ¹H NMR, ¹³C NMR and Mass spectral) confirmed the structure of the newly synthesized compounds. Substituted pyrimidines, pyridazines and quinolines were screened for antibacterial activity against gram-positive and gram-negative bacteria. Selenolo derivative of N-[(4-aminophenyl)sulfonyl] acetamide (substitutent of sulfacetamide c) showed strong bactericidal effect against all the tested organisms. Selenolo[3,2-d]pyrimidin (substitutent a) showed a good bactericidal effect against Serratia marcescens, Staphylococcus aureus and Escherichia coli. Compounds selenolo[2,3-c]pyridazine (substitutent b), selenolo[2,3-b]quinoline(substitutents c)) exhibited a moderate bactericidal effect against Serratia marcescens. None of the synthesized seleno pyridazines has a considerable antimicrobial activity against the tested organisms. The minimum inhibitory concentration (MIC) of the most active compound-3-[4-(N-acetyl sulfamoyl)phenyl]-3,4-dihydro-4-oxo-7,9-dimethylpyrido[3′,2′:4,5]selenolo [3,2-d]pyrimidine was 10 mg ml⁻¹.     

Multisubstituted quinoxalines and pyrido[2,3-d]pyrimidines: Synthesis and SAR study as tyrosine kinase c-Met inhibitors

Two series of new analogues were designed by replacing the quinoline scaffold of our earlier lead 2 (zgwatinib) with quinoxaline and pyrido[2,3-d]pyrimidine frameworks. Moderate c-Met inhibitory activity was observed in the quinoxaline series. Among the pyrido[2,3-d]pyrimidine series, compounds 13a–c possessing an O-linkage were inactive, whilst the N-linked analogues 15a–c retained c-Met inhibitory potency. Highest activity was observed in the 3-nitrobenzyl analog 15b that showed an IC₅₀ value of 6.5 nM. Further structural modifications based on this compound were undergoing.     

Organometallic indolo[3,2-c]quinolines versus indolo[3,2-d]benzazepines: synthesis, structural and spectroscopic characterization, and biological efficacy

The synthesis of ruthenium(II) and osmium(II) arene complexes with the closely related indolo[3,2-c]quinolines N-(11H-indolo[3,2-c]quinolin-6-yl)-ethane-1,2-diamine (L ¹ ) and N′-(11H-indolo[3,2-c]quinolin-6-yl)-N,N-dimethylethane-1,2-diamine (L ² ) and indolo[3,2-d]benzazepines N-(7,12-dihydroindolo-[3,2-d][1]benzazepin-6-yl)-ethane-1,2-diamine (L ³ ) and N′-(7,12-dihydroindolo-[3,2-d][1]benzazepin-6-yl)-N,N-dimethylethane-1,2-diamine (L ⁴ ) of the general formulas [(η⁶-p-cymene)M^II(L ¹ )Cl]Cl, where M is Ru (4) and Os (6), [(η⁶-p-cymene)M^II(L ² )Cl]Cl, where M is Ru (5) and Os (7), [(η⁶-p-cymene)M^II(L ³ )Cl]Cl, where M is Ru (8) and Os (10), and [(η⁶-p-cymene)M^II(L ⁴ )Cl]Cl, where M is Ru (9) and Os (11), is reported. The compounds have been comprehensively characterized by elemental analysis, electrospray ionization mass spectrometry, spectroscopy (IR, UV–vis, and NMR), and X-ray crystallography (L ¹ ·HCl, 4·H₂O, 5, and 9·2.5H₂O). Structure–activity relationships with regard to cytotoxicity and cell cycle effects in human cancer cells as well as cyclin-dependent kinase (cdk) inhibition and DNA intercalation in cell-free settings have been established. The metal-free indolo[3,2-c]quinolines inhibit cancer cell growth in vitro, with IC₅₀ values in the high nanomolar range, whereas those of the related indolo[3,2-d]benzazepines are in the low micromolar range. In cell-free experiments, these classes of compounds inhibit the activity of cdk2/cyclin E, but the much higher cytotoxicity and stronger cell cycle effects of indoloquinolines L ¹ and 7 are not paralleled by a substantially higher kinase inhibition compared with indolobenzazepines L ⁴ and 11, arguing for additional targets and molecular effects, such as intercalation into DNA.