Synthesis and antimicrobial activity of chromone-linked 2-pyridone fused with 1,2,4-triazoles, 1,2,4-triazines and 1,2,4-triazepines ring systems

ARTICLE

Synthesis and antimicrobial activity of chromone-linked 2-pyridone fused with 1,2,4-triazoles, 1,2,4-triazines and 1,2,4-triazepines ring systems

Tarik El-Sayed Ali; Magdy Ahmed Ibrahim^*

Department of Chemistry, Faculty of Education, Ain Shams University, Roxy 11711, Cairo, Egypt

ABSTRACT

Three series of novel fused nitrogen heterocyclic systems such as 1,2,4-triazolo[1,5-α ] pyridines (5-7 and 9), pyrido[1,2-b][1,2,4]triazines (10, 11, 13 and 15), and pyrido[1,2-b][1,2,4]triazepines (17, 18, 20 and 22) linked with a chromone moiety were synthesized from the key intermediate 1,6-diamino-(6-chloro-4-oxo-4H-chromen-3-yl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (4) with some electrophilic reagents. The structures of the novel compounds were established by elemental analyses and spectral data. All the products were also screened invitro for their antimicrobial activity. Compounds 7, 9 and 15 showed the highest activities when compared with the reference drugs.

Keywords: chromone, o-diamine, triazolopyridone, pyridotriazine, pyridotriazepine, antimicrobial activity

RESUMO

Três novas séries de sistemas heterocíclicos nitrogênio fundidos como o 1,2,4-triazol[1,5-α]piridinas (5-7 e 9), pirido[1,2-b][1,2,4]triazinas (10, 11, 13 e 15), e também pirido[1,2-b] [1,2,4]triazepinas (17, 18, 20 e 22) ligadas a um fragmento cromona foram sintetizadas a partir do intermediário-chave 1,6-diamino-(6-cloro-4-oxo-4H-chromen-3-il)-2-oxo-1,2-diidropiridina-3,5-dicarbonitrila (4) com alguns reagentes eletrofílicos. As estruturas dos compostos inéditos foram estabelecidas por análise elementar e dados espectrais. Todos os produtos foram testados quanto à sua atividade antimicrobiana invitro. Os compostos 7, 9 e 15 mostraram as maiores atividades quando comparadas às drogas de referência.

Introduction

The pharmacodynamic versatility of 4-oxo-4H-chromene moiety has been documented not only in many of its synthetic derivatives but also in several naturally occurring flavones and khellins.^1-3 These synthesized and isolated derivatives were found to have a wide range of biological properties including antiinflammatory,⁴ analgesic,⁵ antimicrobial,^6-8 antitumor⁹ and anticancer.¹⁰ Pyridines are an important class of heterocycles due to their practical and synthetic applications.¹¹ In particular, some 2-pyridone derivatives possess diverse bioactivities such as analgesic,¹² antiinflammatory¹³ and anticancer.¹⁴ On the other hand, 1,2,4-triazoles, 1,2,4-triazines and 1,2,4-triazepines have been found to possess a wide spectrum of pharmacological, medicinal and biological activities.^15-20 As part of our research work aiming to the synthesis of a variety of fused heterocyclic systems for biological evaluation, we report here efficient and convenient synthetic methods of different biodynamic nitrogen heterocycles such as 1,2,4-triazoles, 1,2,4-triazines and 1,2,4-triazepines fused with 2-pyridone ring containing a chromone moiety.

Results and Discussion

1,6-Diamino-(6-chloro-4-oxo-4H-chromen-3-yl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (4) was prepared in good yield by refluxing alcoholic solution of [6-chloro-4-oxo-4H-chromen-3-yl)methylene]malononitrile (2) with cyanoacetohydrazide or N´-[(6-chloro-4-oxo-4H-chromen-3-yl)-2-cyanoacetohydrazide (3) with malononitrile in the presence of a catalytic amount of piperidine (Scheme 1). The IR spectrum of compound 4 showed characteristic absorption bands at 3401, 3308 (2 NH₂), 2259 (2 C≡N), 1681 (C=O_pyridone) and 1641 cm^-1 (C=O_pyrone). Also, the ¹H NMR spectrum of 4 exhibited two characteristic singlet signals at d 4.61 (N-NH₂) and 10.78 ppm (C-NH₂). These results indicated the difference in nucleophilicity between the two amino groups. Thus, it is expected that the hydrazide b-nitrogen (N-NH₂) is more nucleophilic and will react more rapidly with the electron deficient carbon than the second amino group (C-NH₂). Product 4 was assumed to be formed via an initial addition of the active methylene of malononitrile to the hydrazone linkage in 3 to yield a Michael adduct A. This adduct dissociates into 2-cyanoacetohydrazide and 2, which then further react in the way described earlier by El-Najar and co-workers²¹ to yield an intermediate tricyanobutyrohydrazide B that cyclizes to intermediates C then D. The intermediate D underwent dehydrogenation to afford the isolated product 4 (Scheme 2).

The 1,6-diamino groups are ready-made nucleophilic centers for the synthesis of fused nitrogen heterocyclic rings.²² Thus, compound 4 is a useful intermediate for the synthesis of new triazolopyridone, pyridotriazine and pyridotriazepine derivatives. Heterocyclization of compound 4 with ethyl formate and acetic anhydride afforded the triazolo[1,5-a]pyridine derivatives 5 and 6, respectively (Scheme 3). The IR and ¹H NMR spectra of the latter compounds confirmed the absence of the two NH₂ groups. Furthermore, their ¹H NMR spectra showed characteristic singlet signal at d 8.61 ppm for H-3 of triazole moiety in compound 5 and two singlet signals at d 2.75 and 2.91 ppm corresponding to the two methyl groups in compound 6.

In continuation to our interest in the synthesis of chromone derivatives containing nitrogen heterocyclic systems,^7,8,23 compound 4 was allowed to react with some chromone derivatives. Thus, cyclocondensation of 4 with 6-chloro-3-formylchromone (1) in DMF under reflux containing few drops of piperidine afforded the 1,2,3,5-tetrahydro[1,2,4] triazolo[1,5-a]pyridine derivative 7. Oxidation of the latter compound by ferric chloride in boiling DMSO yielded 2,7-bis(6-chloro-4-oxo-4H-chromen-3-yl)-5-oxo-1,5-dihydro-1,2,4-triazolo [1,5-a]pyridine-6,8-dicarbonitrile (9). Compound 9 was also obtained by refluxing 4 with 6-chloro-chromone-3-carboxylic acid (8) in phosphorus oxychloride (Scheme 3). The analytical and spectral data of 7 and 9 are in agreement with the proposed structures. Thus, the ¹H NMR spectrum of 7 showed a triplet signal at d 6.99 ppm corresponding to N-CH-N hydrogen of triazole moiety and a doublet signal at d 10.51 ppm due to N²-H hydrogen of the triazole moiety. These two hydrogens were absent in the ¹H NMR spectrum of compound 9 that confirmed the oxidation process of its dihydroanalogue 7.

Next, we allowed compound 4 to react with 1,2-dielectrophilic reagents to develop a facile and convenient route to polysubstituted pyrido[1,2-b][1,2,4]triazine derivatives with an expected wide spectra of biological activities.²⁴ Thus, cyclocondensation of 4 with ethyl 2-chloro-3-oxobutanoate in DMF containing a catalytic amount of piperidine under reflux produced the pyrido[1,2-b][1,2,4]triazine-2-carboxylate derivative 10, which was transformed to the pyrido[1,2-b][1,2,4]triazino[4,5-d][1,2,4]triazine derivative 11 upon fusion with benzoic acid hydrazide (Scheme 4). The IR spectrum of compound 11 exhibited characteristic absorption bands at 3335, 3197 (OH, NH), 2265, 2221 (2 C≡N), 1672 (C=O_pyridone) and 1633 cm^-1 (C=O_pyrone). Also, its ¹H NMR spectrum displayed signals at d 1.91, 10.53 and 13.27 ppm corresponding to methyl, NH and OH hydrogens, respectively. The absence of the triplet and quartet signals corresponding to the ethoxycarbonyl hydrogens of compound 10 supported the formation of compound 11.

On the other hand, the interaction of 4 with 2,3-dichloroquinoxaline (12) and 3-chloro-7,8-diphenyl-4H-1,2,4-triazino[4,3-b][1,2,4]triazine (14) in pyridine led to the formation of the corresponding quinoxalino[2,3-e]pyrido[1,2-b][1,2,4]triazine 13 and pyrido[1,2-b][1,2,4]triazino[3',2':3,4]triazino[5,6-e][1,2,4]triazine 15, respectively (Scheme 4). The ¹H NMR spectrum of 13 showed four broad signals at d 10.72, 11.28, 11.94 and 12.21 ppm assignable to four NH hydrogens which confirmed that the product 13 exists in two tautomeric forms 13A and 13B due to amino-imino tautomerism.

The study was extended to investigate the behavior of 1,6-diaminopyridone derivative 4 towards some 1,3-dielectrophilic reagents which represents a new, simple and efficient synthetic route to prepare pyrido[1,2-b][1,2,4]triazepine derivatives. Therefore, refluxing 4 with acetylacetone and arylidene malononitrile 16 in DMF containing few drops of piperidine as a basic catalyst furnished the pyrido[1,2-b][1,2,4]triazepine derivatives 17 and 18, respectively (Scheme 5). The ¹H NMR spectrum of 17 showed a singlet signal at d 4.63 ppm due to CH₂ hydrogens while compound 18 displayed broad signals at d 8.89 and 10.67 ppm assigned to NH₂ and NH hydrogens, respectively.

Furthermore, we also investigated the reactivity of 4 towards enaminone and ketene N, S-acetal. Thus, reaction of 4 with 4-(dimethylamino)but-3-en-2-one (19) in glacial acetic acid afforded the 5,7-dihydropyrido[1,2-b][1,2,4]triazepine derivative 20 (Scheme 5). The structure of the latter product was confirmed from its elemental analysis which agreed well with the molecular formula C₂₀H₁₀ClN₅O₃. Also, its ¹H NMR spectrum showed a singlet signal at d 2.34 ppm corresponding to the methyl hydrogens, besides a doublet signal at d 7.94 ppm assigned to C₇-H hydrogen of triazepine ring. The formation of compound 20 was assumed to take place via an initial Michael addition of the hydrazide b-nitrogen (N-NH₂) group in 4 to the activated double bond in enaminone followed by cyclization via loss of both dimethylamine and water molecules.²⁴

Finally, treatment of 4 with ketene N, S-acetal derivative 21 in DMF under reflux containing few drops of piperidine produced 2-amino-9-(6-chloro-4-oxo-4H-chromen-3-yl)-8,10-dicyano-N-phenyl-4-(phenylamino)-7-oxo-5,7-dihydropyrido[1,2-b][1,2,4]triazepine-3-carboxamide (22) (Scheme 5). The formation of 22 was assumed to take place via nucleophilic attack of (N-NH₂) on compound 21 to remove methanethiol followed by cycloaddition of the second amino group (C-NH₂) on the nitrile group. The IR spectrum of 22 showed absorption bands for NH₂, NH and C=O_amide groups at 3375-3325, 3152 and 1648 cm^-1, respectively, while its ¹H NMR spectrum showed signals at d 8.08, 9.91, 10.63 and 11.08 ppm assigned to the NH₂ and three NH hydrogens, respectively.

Antimicrobial activity

The standardized disc agar diffusion method ²⁵ was followed to determine the activity of the synthesized compounds against the sensitive organisms Staphylococcus aureus (ATCC 25923) and Streptococcus pyogenes (ATCC 19615) as Gram positive bacteria, Pseudomonas fluorescens (S 97) and Pseudomonas phaseolicola (GSPB 2828) as Gram negative bacteria and two species of fungi, namely Fusarium oxysporum and Aspergillus fumigatus. The antibiotic chloramphenicol was used as reference in the case of Gram negative bacteria, while cephalothin was used in the case of Gram positive bacteria and cycloheximide was used as antifungal reference.

The compounds were dissolved in DMF which has no inhibition activity to get concentration of 2 mg mL^-1. The test was performed on medium potato dextrose agars (PDA) which contain infusion of 200 g potatoes, 6 g dextrose and 15 g agar.²⁶ Uniform size filter paper disks (3 disks per compound) were impregnated with equal volume (10 µL) from the specific concentration of dissolved tested compounds and carefully placed on inoculated agar surface. After incubation for 36 h at 27 ºC in the case of bacteria and for 48 h at 24 ºC in the case of fungi, inhibition of the organisms was measured and used to calculate mean of inhibition zones. Activity index of all the synthesized compounds was also calculated against the corresponding standard drug (Table 1). The products showed various activities against all species of microorganisms which suggest that the variations in the structures affect on the growth of the microorganisms. Thus, we can conclude from these results: i) The prepared compounds showed a moderate to high antimicrobial activity towards all species of bacteria and fungi (Table 1); ii) It is known that compounds having oxygen heterocycles and active hydrogen at nitrogen groups (NH) can be preferable in the design of good bioregulators with desirable prompt biological activity. Also, the chromon-3-yl residue can simultaneously increase the activity and decrease the toxicity of nitrogen heterocycles.²⁷ Thus, the building up of compounds containing more nitrogen heterocycles on the 1,6-diamino-(6-chloro-4-oxo-4H-chromen-3-yl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (4) may enhance the biological activities in most of the products in comparison with compound 4; iii) Compounds which have 1,2,4-triazole ring fused with 2-pyridone showed greater activity than that of 1,2,4-triazine and 1,2,4-triazepine; iv) Compounds 7 and 9 showed the highest antimicrobial activity. This high effect may due to the presence of two chromone moieties besides the triazolopyridone moiety. Also, compound 15 has the same effect which may be attributed to the presence of polyfused bioactive 1,2,4-triazine systems.²⁸ Therefore, these compounds may be considered promising for the development of new antimicrobial agents.

Conclusion

We have successfully synthesized three series of novel fused nitrogen heterocyclic systems such as 1,2,4-triazolo[1,5-a]pyridines, pyrido[1,2-b][1,2,4]triazines and pyrido[1,2-b][1,2,4]triazepines linked with a chromone moiety. The antimicrobial activities of the prepared compounds showed that polyheterocyclic systems 7, 9 and 15 have good inhibitory effects when compared with the starting material.

Experimental

Melting points were determined on a digital Stuart SMP3 apparatus. Infrared spectra were measured on Perkin-Elmer 293 spectrophotometer using KBr disks. ¹H NMR spectra were measured on Gemini-200 spectrometer (200 MHz), using DMSO-d₆ as solvent and TMS (d in ppm) as an internal standard. Elemental microanalyses were performed at Microanalysis Unit in National Research Center. Evaluation of antimicrobial activities was carried out in the Faculty of Agriculture, Al-Azhar University for Girls, Nasr-City, Cairo, Egypt. 6-Chloro-3-formylchromone (1),²⁹ [(6-chloro-4-oxo-4H-chromen-3-yl)methylene] malononitrile (2),³⁰N'-[(6-chloro-4-oxo-4H-chromen-3-yl)methylene]-2-cyanoacetohydrazide (3),³¹ 6-chloro-chromone-3-carboxylic acid (8),³² 3-chloro-7,8-diphenyl-4H-[1,2,4]triazino[4,3-b][1,2,4] triazin-4-one (14)³³ and 2-cyano-3-(methylsulfanyl)-N-phenyl-3-(phenylamino)prop-2-enamide (21)³⁴ were prepared by published methods in literature.

1,6-Diamino-(6-chloro-4-oxo-4H-chromen-3-yl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile(4)

Method A

A mixture of [(6-chloro-4-oxo-4H-chromen-3-yl)methylene]malononitrile (2) (1280 mg, 5 mmol) and cyanoacetohydrazide (500 mg, 5 mmol), in absolute ethanol (30 mL) containing few drops of piperidine, was refluxed for 3 h. After cooling, the formed solid was filtered and recrystallized from DMF to afford 4 as beige crystals, yield 74%, mp 288-289 ºC.

Method B

A mixture of N'-[(6-chloro-4-oxo-4H-chromen-3-yl)methylene]-2-cyanoaceto-hydrazide (3) (1450 mg, 5 mmol) and malononitrile (330 mg, 5 mmol), in absolute ethanol (30 mL) containing few drops of piperidine, was refluxed for 3 h. After cooling, the formed solid was filtered and crystallized from DMF to afford 4 as beige crystals, yield 77%, mp 288-290 ºC. IR (KBr) n_max/cm^-1: 3401, 3308 (2 NH₂), 3058 (C-H_arom), 2259 (2 C≡N), 1681 (C=O_pyridone), 1641 (C=O_pyrone), 1468 (NH₂def.). ¹H NMR (DMSO-d₆) d 4.61 (s, 2H, N-NH₂), 7.13 (d, 1H, J 8 Hz, H-8), 7.54 (d, 1H, J 8 Hz, H-7), 8.53 (s, 1H, H-5), 9.48 (s, 1H, H-2), 10.78 (s, 2H, C-NH₂). Anal. Calc. for C₁₆H₈ClN₅O₃ (353.71): C, 54.33; H, 2.28; N, 19.80; Cl, 10.02. Found: C, 54.01; H, 2.02; N, 19.54; Cl, 9.69%.

7-(6-Chloro-4-oxo-4H-chromen-3-yl)-5-oxo-1,5-dihydro[1,2,4]triazolo[1,5-a]pyridine-6,8-dicarbonitrile (5)

A mixture of compound 4 (1710 mg, 5 mmol) and ethyl formate (370 mg, 5 mmol) in dry pyridine (30 mL) was refluxed for 10 h. After cooling the reaction mixture was poured onto ice and neutralized with concentrated HCl. The formed solid was filtered, washed several times with water and crystallized from DMF/H₂O to give 5 as brown crystals, yield 68%, mp 274-276 ºC. IR (KBr) n_max/cm^-1: 3261 (NH), 3037 (C-H_arom), 2261 (2 C≡N), 1683 (C=O_pyridone), 1638 (C=O_pyrone). ¹H NMR (DMSO-d₆) d 7.10 (d, 1H, J 8.2 Hz, H-8), 7.55 (d, 1H, J 8.2 Hz, H-7), 8.53 (s, 1H, H-5), 8.61 (s, 1H, H-3_triazole), 9.50 (s, 1H, H-2), 10.74 (br, 1H, NH). Anal. Calc. for C₁₇H₆ClN₅O₃ (363.71): C, 56.14; H, 1.66; N, 19.26; Cl, 9.75. Found: C, 55.78; H, 1.52; N, 18.89; Cl, 9.41%.

1-Acetyl-7-(6-chloro-4-oxo-4H-chromen-3-yl)-2-methyl-5-oxo-1,5-dihydro-1,2,4-triazolo [1,5-a]pyridine-6,8-dicarbonitrile (6)

A solution of compound 4 (1710 mg, 5 mmol) in acetic anhydride (10 mL) was refluxed for 6 h. The excess solvent was removed under vacuum to give a solid which was crystallized from ethanol to afford 6 as brown crystals, yield 47%, mp 297-299 ºC. IR (KBr) n_max/cm^-1: 3073 (C-H_arom), 2926 (C-H_aliph), 2239 (2 C≡N), 1722 (C=O_acetyl), 1675 (C=O_pyridone), 1622 (C=O_pyrone). ¹H NMR (DMSO-d₆) d 2.75 (s, 3H, CH₃), 2.91 (s, 3H, CH₃), 7.07-7.97 (m, 2H, H-8 and H-7), 8.66 (s, 1H, H-5), 9.51 (s, 1H, H-2). Anal. Calc. for C₂₀H₁₀ClN₅O₄ (419.77): C, 57.22; H, 2.40; N, 16.68; Cl, 8.44. Found: C, 56.94; H, 2.12; N, 16.32; Cl, 8.07%.

2,7-Bis(6-chloro-4-oxo-4H-chromen-3-yl)-5-oxo-1,2,3,5-tetrahydro[1,2,4]triazolo[1,5-a] pyridine-6,8-dicarbonitrile (7)

A mixture of compound 4 (1710 mg, 5 mmol) and 6-chloro-3-formylchromone (1) (1040 mg, 5 mmol), in DMF (30 mL) containing few drops of piperidine, was refluxed for 5 h. After cooling, the reaction mixture was poured onto ice. The formed solid was filtered and crystallized from DMF/ethanol to afford 7 as yellow crystals, yield 93%, mp > 300 ºC. IR (KBr) n_max/cm^-1: 3395, 3186 (2 NH), 3075 (C-H_arom), 2928 (C-H_aliph), 2263 (2 C≡N), 1680 (C=O_pyridone), 1632 (2 C=O_pyrone). ¹H NMR (DMSO-d₆) d 6.99 (t, 1H, N-CH-N_triazole), 7.37-7.96 (m, 4H, H-8, H-8', H-7 and H-7'), 8.35 (s, 1H, H-5), 8.53 (s, 1H, H-5`), 8.78 (s, 1H, H-2), 9.47 (s, 1H, H-2`), 10.51 (d, 1H, NH), 12.72 (br, 1H, NH). Anal. Calc. for C₂₆H₁₁Cl₂N₅O₅ (544.30): C, 57.37; H, 2.04; N, 12.87; Cl, 13.02. Found: C, 57.02; H, 1.75; N, 12.58; Cl, 12.71%.

2,7-Bis(6-chloro-4-oxo-4H-chromen-3-yl)-5-oxo-1,5-dihydro[1,2,4]triazolo[1,5-a] pyridine-6,8-dicarbonitrile (9)

Method A

A mixture of compound 4 (1710 mg, 5 mmol) and 6-chloro-chromone-3-carboxylic acid (8) (1070 mg, 5 mmol) in POCl₃ (10 mL) was refluxed on water bath for 3 h. After cooling, the reaction mixture was poured onto ice. The formed solid was filtered and crystallized from DMF/ethanol to afford 9 as pale brown crystals, yield 88%; mp > 300 ºC.

Method B

A mixture of compound 7 (1360 mg, 5 mmol) and ferric chloride (2500 mg) in DMSO (25 mL) was refluxed for 4 h. After cooling, the reaction mixture was poured onto 10% aqueous sodium carbonate solution (75 mL) and stirred for 1 h at room temperature. The formed solid was filtered and crystallized from DMF/ethanol to afford 9 as pale brown crystals, yield 82%, mp > 300 ºC. IR (KBr) n_max/cm^-1: 3402 (NH), 3059 (C-H_arom), 2258 (2 C≡N), 1682 (C=O_pyridone), 1641 (2 C=O_pyrone), 1598 (C=N). ¹H NMR (DMSO-d₆) d 7.07-7.79 (m, 4H, H-8, H-8', H-7 and H-7'), 8.35 (s, 1H, H-5), 8.54 (s, 1H, H-5'), 8.68 (s, 1H, H-2), 9.51 (s, 1H, H-2'), 11.64 (br, 1H, NH). Anal. Calc. for C₂₆H₉Cl₂N₅O₅ (542.28): C, 57.59; H, 1.67; N, 12.91; Cl, 13.07. Found: C, 57.22; H, 1.34; N, 12.64; Cl, 12.76%.

Ethyl 8-(6-chloro-4-oxo-4H-chromen-3-yl)-7,9-dicyano-3-methyl-6-oxo-1,6-dihydro-4H-pyrido[1,2-b][1,2,4]triazine-2-carboxylate (10)

A mixture of compound 4 (1710 mg, 5 mmol) and ethyl 2-chloro-3-oxobutanoate (820 mg, 5 mmol), in DMF (30 mL) containing few drops of piperidine, was refluxed for 8 h. After cooling, the reaction mixture was onto ice-water. The formed solid was filtered and crystallized from AcOH/H₂O to afford 10 as brown crystals, yield 69%, mp 188-190 ºC. IR (KBr) n_max/cm^-1: 3394, 3199 (2 NH), 3044 (C-H_arom), 2978, 2925 (C-H_aliph), 2260, 2198 (2 C≡N), 1734 (C=O_ester), 1683 (C=O_pyridone), 1635 (C=O_pyrone), 1103 (C-O-C). ¹H NMR (DMSO-d₆) d 1.24 (t, 3H, J 7.2 Hz, OCH₂CH₃), 2.23 (s, 3H, CH₃), 3.77 (br, 2H, OCH₂CH₃), 7.03-7.93 (m, 2H, H-8 and H-7), 8.53 (s, 1H, H-5), 9.51 (s, 1H, H-2), 10.64 (s, 1H, NH), 11.02 (br, 1H, NH). Anal. Calc. for C₂₂H₁₄ClN₅O₅ (463.83): C, 56.97; H, 3.04; N, 15.10; Cl, 7.64. Found: C, 56.69; H, 2.79; N, 14.78; Cl, 7.28%.

1-Phenyl-10-(6-chloro-4-oxo-4H-chromen-3-yl)-4-hydroxy-5-methyl-8-oxo-6H,8H-pyrido [1,2-b][1,2,4]triazino[4,5-d][1,2,4]triazine-9,11-dicarbonitrile (11)

A mixture of compound 10 (2310 mg, 5 mmol) and benzoic acid hydrazide (680 mg, 5 mmol), containing few drops of triethylamine, was fused for 15 min at 190-200 ºC. The reaction mixture was cooled at room temperature and treated with ethanol (5 mL). The formed solid was filtered and crystallized from ethanol to afford 11 as brown crystals, yield 44%, mp 262-264 ºC. IR (KBr) n_max/cm^-1: 3335 (br, OH), 3197 (NH), 3050 (C-H_arom), 2930 (C-H_aliph), 2265, 2221 (2 C≡N), 1672 (C=O_pyridone), 1633 (C=O_pyrone), 1601 (C=N). ¹H NMR (DMSO-d₆) d 1.91 (br, 3H, CH₃), 7.05-7.95 (m, 7H, H-8, H-7 and Ph-H), 8.52 (s, 1H, H-5), 9.50 (s, 1H, H-2), 10.53 (s, 1H, NH), 13.27 (br, 1H, OH). Anal. Calc. for C₂₇H₁₄ClN₇O₄ (535.89): C, 60.51; H, 2.63; N, 18.30; Cl, 6.61. Found: C, 60.23; H, 2.41; N, 17.98; Cl, 6.29%.

11-(6-Chloro-4-oxo-4H-chromen-3-yl)-9-oxo-9,13-dihydro-7H-quinoxalino[2,3-e]pyrido [1,2-b][1,2,4]triazine-10,12-dicarbonitrile (13)

A mixture of compound 4 (1710 mg, 5 mmol) and 2,3-dichloroquinoxaline (12) (1000 mg, 5 mmol) in dry pyridine (30 mL) was refluxed for 4 h. After cooling, the reaction mixture was poured onto ice-water and neutralized with diluted HCl. The formed solid was filtered and crystallized from DMF/H₂O to afford 13 as pale brown crystals, yield 45%, mp > 300 ºC. IR (KBr) n_max/cm^-1: 3394, (br, NH), 3101 (NH), 3040 (C-H_arom), 2241 (2 C≡N), 1675 (C=O_pyridone), 1619 (C=O_pyrone), 1556 (C=N). ¹H NMR (DMSO-d₆) d 7.01-8.07 (m, 6H, Ar-H), 8.68 (s, 1H, H-5), 9.53 (s, 1H, H-2), 10.72 (br, 1H, NH_triazine), 11.28 (br, 1H, NH_quinaoxaline), 11.94 (br, 1H, NH_triazine), 12.21 (br, 1H, NH_quinaoxaline). Anal. Calc. for C₂₄H₁₀ClN₇O₃ (479.83): C, 60.07; H, 2.10; N, 20.43; Cl, 7.38. Found: C, 59.69; H, 1.86; N, 20.07; Cl, 7.02%.

11-(6-Chloro-4-oxo-4H-chromen-3-yl)-9-oxo-2,3-diphenyl-7H-pyrido[1,2-b][1,2,4] triazino[3`,2`:3,4]triazino[5,6-e][1,2,4]triazine-10,12-dicarbonitrile (15)

A mixture of compound 4 (1710 mg, 5 mmol) and 3-chloro-7,8-diphenyl-4H-[1,2,4]triazino[4,3-b][1,2,4]triazin-4-one (14) (1720 mg, 5 mmol) in dry pyridine (30 mL) was refluxed for 12 h. After cooling, the reaction mixture was poured onto ice-water, and neutralized with diluted HCl. The formed solid was filtered and crystallized from acetic acid to afford 15 as brown crystals, yield 49%, mp 225-227 ºC. IR (KBr) n_max/cm^-1: 3200 (br, NH), 3064 (C-H_arom), 2224 (2 C≡N), 1675 (C=O_pyridone), 1636 (C=O_pyrone), 1600 (C=N). ¹H NMR (DMSO-d₆) d 7.14-8.37 (m, 12H, Ar-H), 8.52 (s, 1H, H-5), 9.46 (s, 1H, H-2), 10.82 (s, 1H, NH). Anal. Calc. for C₃₃H₁₅ClN₁₀O₃ (634.99): C, 62.42; H, 2.38; N, 22.06; Cl, 5.58. Found: C, 62.16; H, 2.07; N, 21.78; Cl, 5.19%.

9-(6-Chloro-4-oxo-4H-chromen-3-yl)-2,4-dimethyl-7-oxo-3,7-dihydropyrido[1,2-b][1,2,4] triazepine-8,10-dicarbonitrile (17)

A mixture of compound 4 (1710 mg, 5 mmol) and acetylacetone (500 mg, 5 mmol), in DMF (30 mL) containing few drops of piperidine, was refluxed for 10 h. After cooling, the reaction mixture was poured onto ice-water. The formed solid was filtered and crystallized from ethanol to afford 17 as brown crystals, yield 59%, mp 182-184 ºC. IR (KBr) n_max/cm^-1: 3042 (C-H_arom), 2977 (C-H_aliph), 2261, 2219 (2 C≡N), 1683 (C=O_pyridone), 1637 (C=O_pyrone), 1600 (C=N). ¹H NMR (DMSO-d₆) d 2.94 (s, 3H, CH₃), 3.16 (s, 3H, CH₃), 4.63 (br, 2H, CH₂), 6.90-7.45 (m, 2H, H-8 and H-7), 8.51 (s, 1H, H-5), 8.96 (s, 1H, H-2). Anal. Calc for C₂₁H₁₂ClN₅O₃ (417.80): C, 60.37; H, 2.89; N, 16.76; Cl, 8.48. Found: C, 60.03; H, 2.57; N, 16.43; Cl, 8.19%.

2-Amino-9-(6-chloro-4-oxo-4H-chromen-3-yl)-4-(4-chlorophenyl)-7-oxo-dihydro-pyrido [1,2-b][1,2,4]triazepine-3,8,10-tricarbonitrile(18)

A mixture of compound 4 (1710 mg, 5 mmol) and (4-chlorobenzylidene) malononitrile (16) (940 mg, 5 mmol), in DMF (30 mL) containing a few drops of piperidine, was refluxed for 10 h. After cooling, the reaction mixture was poured onto ice-water. The formed solid was filtered and crystallized from DMF to afford 18 as red crystals, yield 39%, mp > 300 ºC. IR (KBr) n_max/cm^-1: 3276, 3199 (NH₂, NH), 3070 (C-H_arom), 2276 (2 C≡N), 2216 (C≡N), 1676 (C=O_pyridone), 1619 (C=O_pyrone), 1592 (C=N), 1466 (NH₂def). ¹H NMR (DMSO-d₆) d 7.10-8.19 (m, 6H, Ar-H), 8.61 (s, 1H, H-5), 8.89 (br, 2H, NH₂), 9.54 (s, 1H, H-2), 10.67 (br, 1H, NH). Anal. Calc. for C₂₆H₁₁Cl₂N₇O₃ (540.31): C, 57.80; H, 2.05; N, 18.15; Cl, 13.12. Found: C, 57.52; H, 1.78; N, 17.77; Cl, 12.94%.

9-(6-Chloro-4-oxo-4H-chromen-3-yl)-2-methyl-7-oxo-5,7-dihydropyrido[1,2-b][1,2,4] triazepine-8,10-dicarbonitrile (20)

A mixture of compound 4 (1710 mg, 5 mmol) and 4-(dimethylamino)but-3-en-2-one (19) (570 mg, 5 mmol) in glacial acetic acid (30 mL) was refluxed for 10 h. After cooling, the reaction mixture was poured onto ice-water. The formed solid was filtered and crystallized from DMF/ethanol to afford 20 as pale brown crystals, yield 96%, mp 200-202 ºC. IR (KBr) n_max/cm^-1: 3394 (NH), 3039 (C-H_arom), 2925 (C-H_aliph), 2260 (2 C≡N), 1683 (C=O_pyridone), 1625 (C=O_pyrone), 1597 (C=N). ¹H NMR (DMSO-d₆) d 2.34 (s, 3H, CH₃), 6.91-7.42 (m, 2H, H-8 and C₆-H_triazepine), 7.49 (d, 1H, J 7.8 Hz, H-7), 7.94 (d, 1H, J 8 Hz, C₇-H_triazepine), 8.52 (s, 1H, H-5), 9.46 (s, 1H, H-2), 10.67 (s, 1H, NH). Anal. Calc. for C₂₀H₁₀ClN₅O₃ (403.77): C, 59.49; H, 2.50; N, 17.34; Cl, 8.78. Found: C, 59.13; H, 2.37; N, 16.97; Cl, 8.43%.

2-Amino-9-(6-chloro-4-oxo-4H-chromen-3-yl)-8,10-dicyano-N-phenyl-4-(phenylamino)-7-oxo-5,7-dihydropyrido[1,2-b][1,2,4]triazepine-3-carboxamide (22)

A mixture of compound 4 (1710 mg, 5 mmol) and 2-cyano-3-(methylsulfanyl)-N-phenyl-3-(phenylamino)prop-2-enamide (21) (1550 mg, 5 mmol), in DMF (30 mL) containing few drops of piperidine, was refluxed for 10 h. After cooling, the reaction mixture was poured onto ice-water. The formed solid was filtered and crystallized from DMF/ethanol to afford 22 as pale brown crystals, yield 61%, mp 263-265 ºC. IR (KBr) n_max/cm^-1: 3375, 3325, 3152 (NH₂, 3NH), 3071 (C-H_arom), 2221 (2 C≡N), 1669 (C=O_pyridone), 1648 (C=O_amide), 1630 (C=O_pyrone), 1600 (C=N). ¹H NMR (DMSO-d₆) d 6.94-7.68 (m, 12H, Ar-H), 8.08 (br, 2H, NH₂), 8.66 (s, 1H, H-5), 9.21 (s, 1H, H-2), 9.91 (s, 1H, NH), 10.63 (s, 1H, NH), 11.08 (br, 1H, NH). Anal. Calc. for C₃₂H₁₉ClN₈O₄ (614.99): C, 62.49; H, 3.11; N, 18.22; Cl, 5.76. Found: C, 62.09; H, 2.78; N, 17.81; Cl, 5.43%.

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Received: March 24, 2009

Web Release Date: March 4, 2010

Supplementary Information

Supplementary data are available free of charge at http://jbcs.sbq.org.br, as pdf file.

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Publication Dates

• Publication in this collection
  19 July 2010
• Date of issue
  2010

History

• Accepted
  04 Mar 2010
• Received
  24 Mar 2009