Received 23 June 2015; accepted 5 September 2015; published 8 September 2015

ABSTRACT

Some new fluorinated 3-N-acyl/3-N-alkylaminophenyl-1,2,4-triazino[3,4-b][1,3,4]thiadiazolones (2-12) have been obtained from treatment of 2-(4'-fluorophenyl)-6-(2'-amino-5'-fluorophenyl)- 1,2,4-triazino[3,4-b][1,3,4]thiadiazol-4-one(1) with active functional oxygen, sulfur and halogen compounds in different conditions. Former structures of the products have been characterized from elemental and spectral data (UV, IR, NMR and Mass). The new products were evaluated as potential anthelmintic drugs.

Keywords:

Synthesis, Fluorinated 1,2,4-Triazinothiadiazolones, Anthelmintic Drugs

1. Introduction

The treatment of infectious diseases still remains an important and challenging problem because of a combination of many factors including emerging infectious diseases and the increasing number of multi-drug resistant microbial pathogens [1] -[4] . There is real perceived need for the discovery of new compounds endowed with biocidal activity. Through the various molecules designed and synthesized for this aim, it was demonstrated that fluorinated 1,2,4-triazine fused with 1,3,4-thiadiazole systems. The introduction of fluorine atom to the heterocyclic systems improves or enhances the medicinal properties [5] -[9] . On the other hand, most of heterocyclic nitrogen systems bearing an amino-groups exhibit a wide spectrum of biological activities [10] . And their use is as starting material.

Recently, synthesis and chemistry of 1,3,4-thiadiazoles as biocidal agents have been reviewed [11] [12] . Also, 1,2,4-triazine derivatives have been synthesized and evaluated as biological and pharmacological probes [13] -[15] .

Abdel-Rahman et al. [16] , reported that 1,2,4-triazino[3,4-b][1,3,4]thiadiazolones (Figure 1) used as anti HIV and anticancer drugs. In contamination of our work in these researches for new biocidal agents [17] , the present investigation reports the preparation of fluorinated 3-substitutedamino-1,2,4-triazino[3,4-b][1,3,4]thiadiazolones starting from the corresponding 3-amino analogus, as potential anthelmintic drugs.

2. Results and Discussion

3-Substituted-1,2,4-triazines and their azole-fused analogs reacts with bifunctional compounds give a more stable polycyclic systems depends on the triazine substrate nature. Search for new bioactive compounds, the main aim of the present work is preparation of fluorinated 3-substituted amino-1,2,4-triazino[3,4-b][1,3,4]thiadiazo- lones in view of their pharmacological properties.

Thus, addition of cyclohexyl isocyanate and/or 4-fluorophenyl-isothiocyanate to 3-(2'-amino-5'-fluoro-phenyl) -7-(4'-fluorophenyl)-1,2,4-triazino[3,4-b][1,3,4]thiadiazol-4-one (1) [17] , (Scheme 1) in warm DMF afforded N- (cyclohexyl)-N'-(4'-oxo-1,2,4-triazino[3,4-b][1,3,4] thiadiazol-7'-(4'-fluorophenyl)-3-(4'-fluorophenyl) urea (2) and/or N-(4'-fluorophenyl)-N'-(4'-oxo-1',2',4'-triazino[3,4-b][1,3,4]thiadiazole-7'-(4''-fluoro-phenyl)-3'-(4"-flu- orophenyl)thiourea (3) (Scheme 2). Formation of compound 3 may be tack’s place via a nucleophilic attack of NH₂ group to a more electrophilic carbon of isothiocyanate.

Scheme 1. Synthesis of compound 1.

Acylation of compound 1 using acetyl chloride (DMF) [18] and /orethyltrifluoroacetate in reflux (THF) [19] yielded 3-[(2'-acetylamino)-5'-fluorophenyl]-7-(4'-fluorophenyl)-1,2,4-triazino[3,4-b][1,3,4]thiadiazol-4-one (4) and/or 3-(2'-trifluoroacetylamino-5'-fluoro-phenyl-7-(4'-fluorophenyl)-1,2,4-triazino[3,4-b][1,3,4]thiadiazol-4-one (5) (Scheme 3). Also, self cyclo-condensation of compound 1 via boiling with DMF furnished thiadiazolo-1,2,4- triazinoindole derivative 6 (Scheme 3).

Bonded phosphorus atoms with S, O, N and C-atoms of heterocyclic system enhance their biocidal properties as herbicides, pesticides, insecticides and molluscicidal agents [20] -[22] . With this observations, the present work aims to synthesize of new fused heterobicyclicbearing fluorine and phosphorus atoms through phosphorylation of compound 1 with diphenyl phosphoryl chloride in warm DMF to give 3-(2'-diphenylphosphatoamino-

Scheme 2. Synthesis of compounds 2 and 3.

Scheme 3. Synthesis of compounds 4-6.

5'-flu-orophenyl)-7-(4'-fluorophenyl)-1,2,4-triazino[3,4-b][1,3,4]thiadiazol-4-one (7) (Scheme 4). Due to a highly with drown of P of phosphate moiety, the chlorine atom is very labile. Thus, simple Nu⁻ attack of NH₂ to P atom afforded the aminophosphate derivative.

Full fluorinated 3-[5'-fluoro-2'-(4"-fluorobenzoylamino)phenyl]-7-(4'-fluorophenyl)-1,2,4-triazino[3,4-b][1,3,4] thiadiazole-4-one (8) was obtained from treatment of compound 1 with 4-fluorobenzoylchloride in warm DMF (Scheme 4).

Due to a higher nucleophilicity of amino-group and the better displacement of labile chlorine atom of halo acids the interested point in this investigation is a simple nucleophilic attack of amino-group of compound 1 to a higher electrophilic carbons of α-haloacids as monochloroacetic acid and/or 1,1-dichloroacetic acid in warm DMF, yielded [23] 3-(5"-fluoro-2'-carboxymethylanilino)-7-(4'-fluorophenyl)-1,2,4,-triazino[3,4-b][1,3,4]thia-diazol-4- one (9) and/or 3-(5'-fluoro-2'-carboxymithinicanilino)-7-(4'-fluorophenyl)-1,2,4-triazino[3,4-b][1,3,4] thiadiazol- 4-one (10) (Scheme 5).

Scheme 4. Synthesis of compounds 7 and 8.

Scheme 5. Synthesis of compounds 9 and 10.

Alkylation, reaction of 3-amino-1,2,4-triazinothiadiazolone 1with chloroacetonitrile in warm DMF produced [24] the 3-(5'-fluoro-2'-(cyanomethylanilido)-7-(4'-fluorophenyl)-1,2,4-triazino[3,4-b][1,3,4]thiadiazol-4-one (11) (Scheme 6). Acidic hydrolysis of 11 by reflux with dil. HCl afforded compound 9. Decarboxylation of 9 via warm with sodium bicarbonate solution, 3-(5'-fluoro-2'-(methylanilido)-7-(4'-fluorophenyl)-1,2,4-triazino[3,4-b] [1,3,4] thiadiazol-4-one (12) was isolated. The compound 12 was also, obtained from stirring of compound 1 with MeI in 1% KOH solution (Scheme 6).

The adducts formed by reactions of nitrogen containing aromatic heterocycles with various electrophilic carbon, may be stable systems, or they can undergo further transformation, such as aromatization.

Abdel-Rahmanetal reported [1] [25] , fluorine substituted thiobarbituric acid derivatives use as anti HIV-1 and cyclin dependent kinase 2 (CDK2) for cell tumor division, thus ring closure reaction of compound 3 with malonic acid in boiling with glacial acetic acid afforded the fluorine substituted N,N'-disubstitutedthiobarbituric acid 13 (Scheme 7). Formation of compound 13 was deduced from ring closure reaction of substituted thiourea 3 with malonic acid (Figure 2).

Scheme 6. Synthesis of compounds 11 and 12.

Scheme 7. Synthesis of compounds 13.

Former structures of the fluorinated 1,2,4-triazino[3,4-b][1,3,4]thiadiazolonederivatives have been established by help of their correct elemental analysis and spectral measurements:

1) UV absorption spectra of most N-acyl/phosphoryl derivatives for example 4, 6 and 7 recorded λ_max 304 nm as parent amino-derivatives 1, which is may be that electronic inhibition over NH₂ by high electronic acceptor acyl, and/or phosphoryl. On the other hand, UV absorption spectra of compound 5 and 8 showed λ_max at 311, and 375 nm respectively, which is may be the introduction of COCF₃ and/or COC₆H₄F-p to an amino group of 1. Thus NH proton of these compounds is highly acidic character. In addition, UV absorption spectrum of 13 showed an additive λ_max at 410 nm, which attribute to formation of fluorinated thiobarbituric acid bearing of 1,2,4-triazino-1,3,4-thiadiazinone moiety.

2) IR-spectra of all the obtained compounds (expected 6, 10, and13) recorded the absorption bands at 3200 - 3100 cm for NH functional group, while, that of compounds showed an two C=O of NH acyl and 1,2,4-triazinone at 1690 - 1650 cm⁻¹. All the synthesized showed a charactic bands of stretching and bending of C-F at γ 1250 and 720 cm⁻¹. Only the compounds 7, exhibited the presence of P=O and C-O-Ar at 1097 and 1016 cm⁻¹, while the compounds 4, 9, 11, and 12 showed the absorption bands of aliphatic groups at 2880 and 1440 cm⁻¹. Some compounds as 5, 7, 8, and 11recorded a lack’s of NH functional group, which is may be formation a type of H-bonding (Figure 3).

3) NMR spectra of the new synthesized compounds was confired that structures.

a) ¹H NMR spectra of all the obtained systems exhibited the presence of a resonated signals at δ 8.73 ppm for NH proton (s), in addition, δ at 7.97 - 7.94 and 7.38 - 7.35 ppm for 7 aromatic protons (m). On the other hand, compounds 2, 4, 9, 11, 12, 13 showed signals at 2.51 ppm for an aliphatic protons (COCH_3, CH₂CN, CH₂- COOH, CH₂CO) (J = 8.5). Only the compound 10 recorded δ at 8.8 ppm for N=CH proton (s).

4) ¹³C NMR spectra of all the prepared compounds showed a resonated signals of fluorinated 1,2,4-triazi- no[3,4-b][1,3,4]thiadiazinone carbons at δ 164-163 (C=O), 135 (C-F), 130 - 120 (aromatic C), 116 (C=N) ppm. Only the compound 3 showed a resonated signals at 180 ppm attribute to C=S. On the other hand most

of the new compounds showed an additional δ 160 ppm for new NHCO carbons.

5) Mass fragmentation study of some new systems 5 showed the molecular ion peak, with a base peak at m/e 95 and 190 (100%). The first base peak is 4-fluorophenylradical while the other is 4,4'-difluorobiphenyl radical.. Also present M⁺² is attributed to S and F isotopic (Figure 4).

On the other hand, mass fragmentation study of compound 7 recorded a molecular ion peak at m/e 590 with a base peak at m/e 248 as C₁₂H₁₁NPO₃iminophosphato ion radical with 4-fluorophenyl cation at 95%. Stability of a base peak is may be due to a higher stability of N = P group, which supported by donation and back-donation between N and P atoms (Figure 5).

3. Conclusion

The present work describes a facile and simple nucleophilic attack of amino group bearing fluorine substituted 1,3,4-thiadiazolo[2,3-c][1,2,4]triazine(1) to active electrophilic reagents via addition, fluorinated acylation/ aroylation, phosphorylation and/or alkylation reactions. Substituted amino derivatives were obtained coupling with electronic modifications overall the molecule which led to potential anthelmintic activity. Among the new compounds 5 > 7 > 1 exhibit a higher activity (55% - 60%), while other 13 > 9 > 6 > 4 (45% - 48%) showed a moderate activity towards N. brasiliensis virus. A higher activity of compounds 5 and 7 may be attributed to bourdation of COCF₃ and/or phosphoryl groups with amino groups of start 1.

4. Experimental

Melting points of the products were determined on Stuart SMP₃ (UK) and uncorrected. UV absorption spectra (λ_max nm) were recorded in DMF on Shimadzu UV and visable 310 IPC-spectro-photometer. A Perkins Elmer Model RXI-FT IR system 55529 used for recording IR spectra of the prepared compounds γ cm⁻¹. A Brucker advanced D P X 400 MHz model using TMS as internal standard used for recording the ¹H and ¹³C NMR spectra of the compounds on deuterated (CDCl₃, d₆, δ ppm). Mass spectrum was measured on GCMS Q 1000 Ex at 70 eV. Elemental microanalysis were performed by the microanalytical at Cairo-University, Egypt.

4.1. 3-(2'-Amino-5'-fluorophenyl)-7-(4'-fluorophenyl)-1,2,4-triazino[3,4-b][1,3,4] thiadi-azin-4-one (1)

Equimolar amounts of 5-fluoroisatin (in 5% aqueous NaOH), and 2-hydrazino-2-(4'-fluorophenyl)-4H-1,3,4-

thiadiazole and reflux for 3 h, cooled then poured on to ice-HCl. The solid thus obtained filtered off and crystallized from dioxan to give 1 faint yellow crystals, yield 77%, m.p. 189˚C - 195˚C. UV (EtOH) λ_max 303nm. IR (γ cm⁻¹): 3264 and 1631 (NH₂), 1681 (C=O), 1601, 1507 (C=N), 1320 (cyclic NCSN), 1225 (C-F), 1156 (C-S), 826 (p-substituted phenyl), 618 (C-F). ¹H NMR (DCCl₃-d₆) δ (ppm): 8.61 - 7.84, 7.84 - 7.83, 7.82 - 7.81, 7.818 - 7.812, 7.24,7.15,7.14, 7.13, 7.115, 7.110 (aromatic CH), 3.5 (s, 2H, NH₂). ¹³C NMR (DCCl₃-d₆) δ (ppm): 165, 163, 160, 130.58, 130.49, 130.37, 116.15, 115.93, 77.34, 77.03, 76.71. M/Z: (Int.%): 357 (57% M⁺ H₂O) 244 (1.0), 206 (15.0), 178 (100), 134 (45), 95 (25.0). CHNSF analysis for C₁₆H₉N₅SF₂O (357), Calcd: C, 53.78; H, 2.52; N, 19.60; S, 8.63; F, 10.64%. Found: C, 53.58; H, 2.32; N, 19.55; S, 8.33; F, 10.43%.

4.2. N-(Cyclohexyl)-N'-[4'-oxo-1,2,4-triazino[3,4-b][1,3,4]thiadiazol-7'- (4"-fluorophenyl)-3'-(4"-fluorophenyl)]-urea (2).

A mixture of compound 1 (0.01 mol) and cyclohexyl isocyanate (0.01 mol) in DMF (50 ml) warmed for 2h, cooled then poured onto ice. The solid produced filtered off and crystallized from dioxan to give 2 as faint yellow. Yield 60%, m.p. 178˚C - 180˚C. IR (γ) cm⁻¹: 3325 (NH), 2928, 2851 (aliphatic CH, CH₂) 1700 (C=O), 1629 (CONH), 1602 (C=N), 1413 (deformation CH₂), 1320 (cyclic NCSN), 1225 (C-F), 1155 (C-S), 826, 796 (p-substituted phenyl), 635 (C-F). ¹H NMR (DMSO-d₆) δ (ppm): 8.73 (s, 2H, NH, NH), 7.97, 7.96, 7.95, 7.94 (4H, aryl protons), 7.38, 7.37, 7.35 (3H, aryl protons), 2.511, 1.8, 1.7, 1.6, 1.2, (each s, 11H, aliphatic protons). ¹³C NMR (DMSO-d₆) δ (ppm): 168.4, 163.4 (2 C=O), 160 (C-S), 130.71, 130.65, 130.38, 130.36 (aromatic carbons), 116, 116.1 (C-F), 33.32, 25.28, 24.45 (aliphatic carbons). CHNSF analysis for C₂₃H₂₀N₆SF₂O₂ (482). Calcd: C, 57.26; H, 4.14; N, 17.42; S, 6.6; F, 7.88%. Found: C, 56.96; H, 4.05; N, 17.11; S, 6.33; F, 7.75%.

4.3. N-(4'-Fluorophenyl)-N'-[(4'-oxo-1',2',4'-triazino[3,4-b][1,3,4]thiadiazol-7'- (4"-fluoro-phenyl)-3'-(4"-fluorophenyl)]thiourea (3)

A mixture of 1 (0.01 mol) and 4-fluorophenyl isothiocyanate (0.01 mol) in DMF (20 ml) was refluxed for 1h, cooled then poured onto ice. The yielded solid filtered off and crystallized from EtOH to give 3 as yellow crystals. Yield 72%, m.p. 164˚C - 165˚C. IR (γ) cm⁻¹: 3272 (NH), 3016 (aromatic CH), 1695 (C=O), 1612 (C=N), 1600 (C=C), 1328 (cyclic NCSN), 1225 (C-F), 1208 (C=S), 1154 (C-S), 829,732, 719 (p-substituted phenyl), 639 (C-F).¹H NMR (DMSO-d₆) δ (ppm): 9.76, 8.73 (each s, 2H, NH), 7.97, 7.95, 7.47, 7.46, 7.45, 7.44, 7.38, 7.35, 7.18, 7.14, 7.11 (m, m, 11H, aromatic protons). ¹³C NMR (DMSO-d₆) δ (ppm): 180.29 (C=S), 164.7 (C=O), 135.98, 135.62, 135.61 (C-N), 130.71, 126.24 (aromatic carbons), 119.97, 119.92 (C-N), 116.14, 115.32, 114.98 (C-F). CHNSF analysis for C₂₃H₁₃N₆S₂F₃O (510). Calcd: C, 54.11; H, 2.54; N, 16.47; S, 12.54; F, 11.17%. Found: C, 53.98; H, 2.48; N, 16.24; S, 12.38; F, 10.27%.

4.4. 3-[(2'-Acetylamino)-5'-fluorophenyl]-7-(4'-fluorophenyl)-1,2,4-triazino[3,4-b] [1,3,4]thiadiazol-4-one (4)

A mixture of 1 (0.200 gm) and glacial acetic acid (5 ml) was warmed for 5 min, cooled then poured onto ice. The solid produced filtered off and crystallized from AcOH to give 4 as pall yellow crystals. Yield 55%, m.p. 182˚C - 183˚C. IR (γ) cm⁻¹: 3123 (NH), 1632 (C=O), 1603 (C=N), 1414 (deformation CH₃), 1321 (cyclic NCSN), 1225 (C-F), 1155 (C-S), 827, 795 (p-substituted phenyl), 635 (C-F). ¹H NMR (DMSO-d₆) δ (ppm): 8.73 (s,1H, NH), 7.97, 7.96, 7.95, 7.94 (m, 4H, aromatic protons), 7.38, 7.37, 7.3 (m, 3H, aromatic protons) 2.51 (s, 3H, CH₃). ¹³C NMR (DMSO-d₆) δ (ppm): 164.71 (C=O), 160.50 (C=O), 130.71, 130.65, 130.36, (aromatic carbons), 116.15, 116.0 (C-F), 39.03 (CH₃). CHNSF analysis for C₁₈H₁₁N₅SF₂O (399). Calcd: C, 54.13; H, 2.75; N, 17.54; S, 8.0; F, 9.52%. Found: C, 53.88; H, 2.69; N, 17.32; S, 7.75; F, 9.40%.

4.5. 3-(2'-Trifluoroacetylamino-5'-fluorophenyl)-7-(4'-fluorophenyl)-1,2,4-triazino [3,4-b][1,3,4]thiadiazol-4-one (5)

Equimolar mixture of 1 and trifluoroethyl acetate in THF (50 ml) refluxed for 2 h, cooled. The solid thus obtained filtered off and crystallized from dioxan to give 5 as white crystals. Yield 82%, m.p. 179˚C - 180˚C. IR (γ) cm⁻¹: 1632 (C=O), 1603 (C=N), 1321 (cyclic NCSN), 1225 (C-F), 1155 (C-S), 827, 795 (p-substituted phenyl), 635 (C-F). ¹H NMR (DMSO-d₆) δ (ppm): 8.73 (s,1H, NH), 7.97, 7.96, 7.95, 7.94 (4H, aromatic protons), 7.38, 7.37, 7.35 (3H, aromatic protons). ¹³C NMR (DMSO-d₆) δ (ppm): 164.71 (C=O), 160.50 (C=O), 130.71, 130.65, 130.38, 130.36 (aromatic carbons), 116.14, 116.00 (C-F). M/S (Int.%): 455 (M⁺2, 0.11%), 190 (100), 153 (85.0), 138 (3.33), 95 (100), 66 (1.181, 60, 13.0). CHNSF analysis for C₁₈H₈N₅SF₂O₂ (455, M+2). Calcd: C, 47.68; H, 1.76; N, 15.45; S, 7.06; F, 20.97%. Found: C, 47.38; H, 1.73; N, 15.19; S, 6.88; F, 20.67%.

4.6. 10-(4'-Fluorophenyl)-4-fluoro-1,3,4-thiadiazolo[2,3-c][1,2,4]triazino[5,6-b]indole (6)

Compounds 1 (0.20 gm) in DMF (20 ml) refluxed for 3h, cooled then poured onto ice. The yielded solid filtered off and crystallized from EtOH to give 6 as yellowish crystals. Yield 60%, m.p. 184˚C - 185˚C. IR (γ) cm⁻¹: 1603 (C=N), 1321 (cyclic NCSN), 1226 (C-F), 1155 (C-S), 827, 796 (p-substituted phenyl), 635 (C-F). ¹H NMR (DMSO-d₆) δ (ppm): 7.97, 7.96, 7.95, 7.94 (4H, aromatic protons), 7.38, 7.37, 7.35 (3H, aromatic protons).¹³C NMR (DMSO-d₆) δ (ppm): 130.71, 130.65, 130.38, 130.36 (aromatic carbons), 116.14, 116.0 (C-F). CHNSF analysis for C₁₆H₇N₅SF₂ (339). Calcd: C, 56.63; H, 20.6; N, 20.6; S, 9.43; F, 11.20%. Found: C, 56.55; H, 2.03; N, 20.18; S, 9.14; F, 10.98%.

4.7. 3-(2'-Diphenylphosphatoamino-5'-fluorophenyl)-7-(4'-fluorophenyl)-1,2,4- triazino[3,4-b][1,3,4]thiadiazol-4-one (7)

An equimolar mixture of 1 (0.01 mol) and diphenyl phosphoryl chloride (0.01mol) in DMF (20 ml) refluxed for 30 min, then, cooled and poured onto ice. The produced solid filtered off and crystallized from THF to give 7 as yellowish crystals, yield 60%, m.p. 173˚C - 175˚C. IR (γ) cm⁻¹: 3061(aromatic CH), 1632 (C=O), 1602 (C=N), 1320 (cyclic NCSN), 1225 (C-F), 1155 (C-S), 1097 (P=O), 1016 (Ph-O-P), 962, 936, 870, 827, 795 (substituted phenyl), 635 (C-F). ¹H NMR (DMSO-d₆) δ (ppm): 8.73 (s,1H, NH), 7.97, 7.96, 7.95, 7.94 (4H, aromatic protons), 7.38, 7.37, 7.35 (3H, aromatic protons), 7.2-6.8 (m,10H, phenyl protons). ¹³C NMR (DMSO-d₆) δ (ppm): 160.50 (C=O), 130.71, 130.65, 130.38, 130.36 (aromatic carbons), 116.14, 116.0 (C-F). M/S (Int.%):590 (M⁺, 0.11%), 248 (100), 247 (11.8), 95 (95.0). CHNSF analysis for C₂₈H₁₈N₅SF₂PO₄ (589). Calcd: C, 57.04; H, 3.05; N, 11.88; S, 5.43; F, 6.45%. Found: C, 57.01; H, 2.98; N, 11.60; S, 5.37; F, 6.14%.

4.8. 3-[5'-Fluoro-2'-(4"-fluorobenzoylamino)-phenyl]-7-(4'-fluorophenyl)-1,2,4- triazino[3,4-b][1,3,4]thiadiazol-4-one (8)

A mixture of 1 (0.01 mol) and 4-fluorobenzoyl chloride (0.01 mol) in DMF (20 ml) refluxed 1 h, cooled. The reaction mixture poured onto ice. The solid produced filtered off and crystallized from dioxan to give 8 as yellowish crystals, yield 65%, m.p. 149˚C - 150˚C. IR (γ) cm⁻¹: 3200-3100 (b, OH, NH), 1677 (cyclic C=O), 1633 (NHCO), 1602 (C=N), 1315 (cyclic NCSN), 1225 (C-F), 1156 (C-S), 827, 796, 768 (p-substituted phenyl), 635 (C-F). ¹H NMR (DMSO-d₆) δ (ppm): 13.09 (s,1H, NH), 8.02, 8.05, 8.01, (m, 3H, aromatic protons), 7.97, 7.96, 7.95, 7.94 (m, 4H, aromatic protons), 7.38-7.32 (m, 4H, aromatic protons). ¹³C NMR (DMSO-d₆) δ (ppm): 166.36, 164.04 (2 C=O), 132.11, 132.05, 130.65, 130.38, 130.36, 127.33 (aromatic carbons), 116.15, 116.0 (C-F), 115.69, 115.54 (C-N). CHNSF analysis for C₂₂H₁₂N₅SF₃O₂ (467). Calcd: C, 56.53; H, 2.56; N, 14.98; S, 6.85; F, 12.20%. Found: C, 56.28; H, 2.50; N, 14.53; S, 6.67; F, 12.00%.

4.9. 3-(5'-Fluoro-2'-carboxymethylanilino)-7-(4'-fluorophenyl)-1,2,4-triazino[3,4-b] [1,3,4]thiadiazol-4-one (9)

A mixture of 1(0.01 mol) and monochloroacetic acid (0.01 mol) in DMF (20 ml) refluxed for 1h, cooled then poured onto ice. The solid produced filtered off and crystallized from THF to give 9 as yellowish crystals, yield 72%, m.p. 180˚C - 182˚C. IR (γ) cm⁻¹: 3500 - 3100 (b, OH, NH), 1720, 1633 (2 C=O), 1603 (C=N), 1490, 1413 (deformation CH₂), 1321 (cyclic NCSN), 1226 (C-F), 1156 (C-S), 826, 796 (substituted phenyl), 636 (C-F). ¹H NMR (DMSO-d₆) δ (ppm): 8.73 (s,1H, NH), 7.97, 7.96, 7.95, 7.94 (m, 4H, aromatic), 7.38, 7.37, 7.35 (m, 3H, aromatic), 4.55 (s, 1H, OH), 2.51 (s, 2H, J,8.7, CH₂). ¹³C NMR (DMSO-d₆) δ (ppm): 164.71 (C=O), 163.06 (C=O), 130.70, 130.65, 130.38, 130.36(aromatic carbons), 116.14, 116.0 (C-F), 39.03 (CH₂). CHNSF analysis for C₁₈H₁₁N₅SFO₃ (415). Calcd: C, 52.53; H, 2.65; N, 16.86; S, 7.71; F, 9.15%. Found: C, 52.33; H, 2.62; N, 16.59; S, 7.62; F, 9.04%.

4.10. 3-(5'-Fluoro-2'-carboxymethinicanilino)-7-(4'-fluorophenyl)-1,2,4-triazino [3,4-b][1,3,4]thiadiazol-4-one (10)

A mixture of 1 (0.01 mol) and 1,1'-dichloroacetic acid (0.01 mol) in DMF (20 ml) refluxed for 30 min, cooled then poured onto ice. The solid thus obtained filtered off and crystallized from EtOH to give 10 as yellowish crystals, yield 60%, m.p. 154-155˚C. IR (γ) cm⁻¹: 3500 - 3300 (OH), 1696, 1632 (C=O), 1602 (C=N), 1321 (cyclic NCSN), 1226 (C-F), 1155 (C-S), 826, 796 (substituted phenyl), 635 (C-F). ¹H NMR (DMSO-d₆) δ (ppm): 8.8 (s,1H, N=CH), 7.97, 7.96, 7.95, 7.94 (m, 4H, aromatic), 7.38, 7.37, 7.35 (m, 3H, aromatic), 4.41 (s, 1H, OH). ¹³C NMR (DMSO-d₆) δ (ppm): 164.71 (C=O), 163.06 (C=O), 130.71, 130.65, 130.38, 130.36, 128.72, 127.25 (aromatic carbons), 116.14, 116.0 (C-F). CHNSF analysis for C₁₈H₉N₅SFO₃ (413). Calcd: C, 52.30; H, 2.17; N, 16.94; S, 7.74; F, 9.20%. Found: C, 52.08; H, 2.11; N, 16.55; S, 7.54; F, 8.89%.

4.11. 3-(5"-Fluoro-2'-cyanomethylanilino)-7-(4'-fluorophenyl)-1,2,4-triazino[3,4-b] [1,3,4]thiadiazol-4-one (11)

Equimolar amounts of 1 and chloroacetonitrile in DMF (20 ml) refluxed for 1h, cooled then poured onto ice. The solid produced filtered off and crystallized from THF to give 11 as brown crystals, yield 65%, m.p. 177˚C - 178˚C. IR (γ) cm⁻¹: 3180 (NH), 2220 (C N), 1635 (C=O), 1507, 1413 (deformation CH₂), 1320 (Cyclic NCSN), 1225 (C-F), 1155 (C-S), 226, 796 (Substituted phenyl), 635 (C-F).¹H NMR (DMSO-d₆) δ (ppm): 8.73 (s,1H, NH), 7.97, 7.96, 7.95, 7.94 (4H, aromatic), 7.38, 7.37, 7.35 (m, 3H, aromatic), 3.36 (2H, J, 6.6 p.c.s, CH₂).¹³C NMR (DMSO-d₆) δ (ppm): 160.50 (C=O), 130.71, 130.65, 130.38, 130.36, 128.91, 127.88 (aromatic carbons), 116.14, 116.0 (C-F), 39.03 (CH₂CN). CHNSF analysis for C₁₈H₁₀N₆SF₂O(396). Calcd: C, 54.54; H, 2.52; N, 21.21; S, 8.08; F, 9.59%. Found: C, 54.31; H, 2.50; N, 20.89; S, 7.98; F, 9.41%.

4.12. 3-(5'-fluoro-2'-Methylanilino)-7-(4'-Fluorophenyl)-1,2,4-Triazino[3,4-b][1,3,4] Thiadi-Azol-4-One (12)

A mixture of 9 (0.20 gm) and K₂CO₃solution (5%, 50 ml) refluxed for 1h, cooled then acidification use 5% HCl. The solid obtained filtered off and crystallized from EtOH to give 12 as brownish crystals, yield 55%, m.p. 178˚C - 180˚C. IR (γ) cm⁻¹: 3062 (aromatic CH), 1700, 1632 (C=O), 1600 (C=N), 1507, 1413 (deformation CH₃), 1321 (cyclic NCSN), 1225 (C-F), 1155 (C-S), 820, 795 (Substituted phenyl), 635 (C-F). ¹H NMR (DMSO-d₆) δ (ppm): 8.73 (s,1H, NH), 7.97, 7.96, 7.95, 7.94 (m, 4H, aromatic), 7.38, 7.37, 7.35 (m, 3H, aromatic), 2.22 (s, 3H, CH₃N). ¹³C NMR (DMSO-d₆) δ (ppm): 160.11 (C=O), 130.71, 130.65, 130.38, 130.36, 128.72 (aromatic carbons), 116.14, 116.0 (C-F), 22.65(CH₃). CHNSF analysis for C₁₇H₁₁N₅SF₂O(371). Calcd: C, 54.98; H, 2.96; N, 18.86; S, 8.62; F, 10.24%. Found: C, 54.69; H, 2.22; N, 18.43; S, 8.49; F, 9.98%.

4.13. Formation of 9

A mixture of 11 (0.20 gm) and diluted HCl (10%, 50 ml) refluxed for 1h, coled. The solid produced filtered off and crystallized from THF to give 9 as yellowish crystals, yield 60%, m.p. 178˚C - 179˚C. Mixed melting point no depression.

4.14. N'[2'-(4"-Fluorophenyl)-5-oxo-6-(5'-fluorophenyl-2"-yl)-N3-(4'-fluorophenyl)- thiobarbituric acid (13)

Equimolar mixture of 3 and malonic acid in glacial acetic acid (20 ml) refluxed for 4 h, cooled and poured onto ice. Extracted the organic layer by diethyl ether and leaf at room temperature. The solid obtained crystallized from dioxan to give 13 faint yellow crystals, yield 65%, m.p. 150˚C - 151˚C. IR (γ) cm⁻¹: 3530 (OH), 1660 (C=O), 1488 (deformation CH₂), 1385 (NCSN), 1255 (C-F), 1205 (C=S), 670 (C-F). ¹H NMR (DMSO-d₆) δ (ppm): 10.04 (s,1H,OH), 8.2 - 8.0 (m, 4H, aromatic protons), 7.60-7.44 (m, 4H, aromatic protons),7.0 - 6.98 (m, 3H, aromatic protons), 3.55, 2.59 - 2.58 (s, 2H, CH₂). ¹³C NMR (DMSO-d₆) δ (ppm): 181.10, 165.71, 160.00, 159.38, 138.2, 133.40, 134.20, 126.91, 126.80, 125.1, 121.69, 115.45, 115.21, 77.79, 77.57, 77.36, 44.36, 40.46-39.8). CHNSF analysis for C₃₆H₁₃N₆S₂F₃O₃ (578). Calcd: C, 53.97; H, 2.24; N, 14.53; S, 11.67; F, 9.86%. Found: C, 53.79; H, 2.11; N, 14.33; S, 11.55; F, 9.59%.

5. Pharmacological Evaluation

1,2,4-Triazine derivatives showed a wide biocidal spectrum [13] -[15] . Also, 1,3,4-thiadiazoles exhibited a large biocidal agents [11] [12] . In addition, introduction of both fluorine atoms and/or amino groups to heterocyclic systems often improve their medicinal properties [5] -[9] . Thus, in search for new drugs as potential anthelmintic to control on the smoke diseases, the present work, aim to obtain new drugs. All the new synthesized compounds were screened for their anthelmintic activity against H. nana infection in mice, by using the standard method of steward. The oral dose was 200 mg/Kg given for 2 days. Only the compounds 1, 3, 5, 6, 7, 9 and 13 recorded a weak activity (10 <%). On the other hand, evaluation of these compounds against N-brasiliensis infection in rats ta the same oral dose, by using other standard method [26] [27] . The obtained results showed that the activity in range of 25% - 60% (Table 1).

From the obtained results (Table 1) we can be conclude that compounds containing COCF₃ are highly effect than aromatic C-F. also, presence of phosphate group bonded to NH enhance that activity. Full fluorinated

N,N'-diarylthiourea showed a rise activity towards N-brasifiensis. As well as N-alkyl systems exhibited a moderate activity. Thus, atype of both compounds 5 and 7 would present a fruitful matrix for the future development of a new class of potential anthelmintic agents, that deserves further investigation and derivation. A simple of nucleophilic attack of amino group of fluorinated 1,2,4-triazino[2,3-c]thiadiazolone to various electrophilic agents was deduced to give N-substituted analogues. The anthelmintic activity of these systems was evaluated. Among these tested analogs, compounds 5 and 7 showed 50% - 60% activity, while all the tested compounds exhibited below 10% activity towards H. nana.

Cite this paper

Mohammed Saleh TawfekMakki,Reda Mohammady AbdelRahman,Ola Ahmad AbuAli, (2015) Synthesis of New Fluorinated 1,2,4-Triazino [3,4-b][1,3,4]thiadiazolones as Antiviral Probes-Part II-Reactivities of Fluorinated 3-Aminophenyl-1,2,4-triazinothiadiazolone. International Journal of Organic Chemistry,05,153-165. doi: 10.4236/ijoc.2015.53017

References

NOTES

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