Received 22 April 2014; revised 5 June 2014; accepted 22 June 2014

ABSTRACT

New fluorine substituted 6-(5’-fluoro-2’-triphenylphosphiniminophenyl) 3-thioxo-1,2,4-triazin-5 (2H, 4H) one (2) was obtained via Wittig’s reaction of the corresponding 6-(5’-fluoro-2’-amino- phenyl)-3-thioxo-1,2,4-triazinone (1). Behavior of compound 2 towards alkylating agents and/or oxidizing agents was studied were, N-hydroxyl (3), Mannich base (4,5), S-alkyl (6,7,8) and thiazolo [3,2-b][1,2,4] triazinones (10-14) and or 3-disulfide (18), 3-sulfonic acid 19 and 1,2,4-triazin-3,5- Dionne (20) derivatives obtained. Structures of the new products are established by elemental and spectral data. The new targets obtained screened as Molluscicidalagents against Biomophlaria Alexandrina snails responsible for Bilharziasis diseases, in compare with Baylucide as standard drug.

Keywords:

Fluorine, Phosphorus, Sulfur-1,2,4-Triazine, Characteristic Properties, Molluscicidal Activity

1. Introduction

The incorporation of fluorine atoms into a heterocyclic nitrogen molecule frequently provides properties of pharmacological interest as compared to their non-fluorinated analogs [1] -[5] . Also, bonded phosphorus atoms with S, O, N and C-atoms of heterocyclic systems enhance their important properties as herbicides, pesticides and insecticides [6] -[11] . On the other hand, 3-thioxo-1,2,4-triazin-5-one derivatives and their N- and S-alkyl derivatives have gained considerable attention due to their well as medicinal utility such as anti-HIV, anti AIDS and anticancer agents [12] -[16] . Literature reveals that no reports of a molecular scaffold containing these im- portant cores. With this based upon these observations. The present work aims to synthesis and chemical reac- tivity of 1,2,4-triazinone bearing, fluorine, phosphorus and sulfur atoms through alkylation reactions and the new systems as Molluscicidal agents against Biomophalaria Alexandrina snails by removal from the wastewater (Clean water).

2. Experimental

Melting points were determined with an electro-thermal Bibbly Stuart Scientific Melting point SMPI (UK). A Perkin Elmer (Lambda EZ-210) double beam spectrophotometer (190 - 1100 nm) used for recording the elec- tronic spectra. A Perkin Elmer model RXI-FT-IR 55,529 cm⁻¹ used for recording the IR spectra (EtOH as sol- vents). A Brucker advance DPX 400 MHz using TMS as an internal standard for recording the ¹H/¹³C NMR spectra in deuterated DMSO (δ in ppm). AGC-MS-QP 1000 Ex model is used for recording the mass spectra. Hexafluorobenzene was used as external standard for ¹⁹F NMR at 8425 MHz and ³¹P (in CDCl₃, 101.25 MHz) [17] . Elemental analysis was performed on Micro Analytical Center of National Reaches Center-Dokki, Cairo, Egypt. Compound 1 was prepared according the reported method [14] and compound 15 as procedure published [18] .

6-(5’-Fluor phenyl)2’amino-3-thioxo-1,2,4-triazine-5(2H, 4H)one (1)

Equimolar mixture of 5-fluoroisatin (in 100 ml NaOH, 5%) and thiosemicarbazide (in 10 ml H₂O) reflux for 2 h, then cold and poured onto ice-HCl. The solid result was filtered off and crystallized from EtOH as yellow crystals to give 1. Yield (80%), m.p. 263˚C - 265˚C. Analytical data, Found C = 44.91, H = 2.90, F = 7.58, N = 23.40, S = 13.29%; Calculated for C₉H₇FN₄OS (238) C = 45.37, H = 2.94, F = 7.98 N = 23.52, S = 13.44%, M/Z (256, M + H₂O, 5%), base peak (68, 100%), 148 (21), 136 (18), 110 (30), 96 (50), 82 (58), 70 (78); UV: (λ_max EtOH) 280 nm. IR νcm⁻¹ = 3424 (NH₂) 3258, 3169 (NH, NH), 1685 (C=O), 1618 (NH₂), 1545 (C=N), 1263 (C-F): 858, 818 (aryl CH) 685 (C-F) ¹H NMR (DMSO) = 14.66, 16.66, 10.90 (each 1H, s, 3NH), 8.68 - 8.06, 7.69 - 7.64, 7.39, 7.39 - 7.30 (3H, aryl protons) ¹³C NMR = δ 179.47 (C=S), 162 (C=O), 159 - 157 (spin coupl- ing C-F), 138.54 (C=N), 131.82, 121.8, 121.51 (aromatic carbons), 78.14, 77.71 (C5-C6 1,2,4-triazine).

6-[5’-Fluoro-2’(triphenylphosphinimino)phenyl]-3-thioxo-1,2,4-triazine-5(2H, 4H)one (2)

A mixture of 1 (0.01 mol) and triphenyl phosphine (0.01 mol) in acetonitrile (20 ml), THF (20 ml) reflux for 2 h then cold. The solid produced and crystallized from EtOH to give 2 as deep yellowish crystals. Yield (70%) m.p. 249˚C - 250˚C. Analytical date Found C = 64.60, H = 3.96, F = 3.70, N = 11.01, S = 6.33%. Calculated for C₂₇H₂₀FN₄OPS (498): C = 65.06, H = 4.01, F = 3.81, N = 11.24, S = 6.42%, M/Z (498.00) 370 (4), 290 (10), 171 (60), 159 (100), 128 (20), 118 (40), 102 (65), 92 (58), 76 (58), 65 (40); UV: (λ_max EtOH) 310 nm. IR νcm⁻¹ = 3335 (NH), 1658 (C=O), 1380 (P=N), 1250 (C-F), 1087 (C-S) 1045, (P-N) 879 (aryl CH), 650 (C-F). ¹H NMR (DMSO): 14.56, 12.78 (each 1H, s, 2NH), 8.21, 7.76, 7.66, 7.65, 7.65, 7.64, 7.484, 7.840, 7.47, 7.464, 7.460, 7.45, 7.398, 7.391, 7.38, 7.37, 7.29, 7.28, 7.28, 7.27, 7.02, 7.01, 7.009, 7.005, 6.994, 6.990, 6.866, 6.859, 6.852, 6.845, (18H of aromatic protons). ¹³C NMR (DMSO) = δ 179.74 (C=S), 163.0 (C=O), 138.62 (C-F), 131 (C=N), 118.94 - 107.94 (aromatic carbons), 7.76, 77.21 (C₅-C₆ of 1,2,4-triazine).

2,4-Di(hydroxymethyl)-6-(5’-fluoro-2’-triphenylphosphiniminophenyl)-3-thioxo-1,2,4-triazine-5-one (3)

A mixture of 2 (0.01 mol) and formaldehyde (0.02 mol), in methanol (50 ml) reflux for 2 h, cold. The solid obtained filtered off and crystallized from MeOH to give 2 as faint yellow crystals. Yield = (65%) m.p. 280˚C - 282˚C. Analytical date: Found C = 61.92, H = 4.21, F = 5.23, N = 9.93, S = 5.43% Calculated for C₂₉H₂₄FN₄PSO₃ (558): C = 62.36, H = 4.30, F = 3.40, N = 10.03, S = 5.73%. UV: (λ_max EtOH) = 363 nm. IR νcm⁻¹ = 3346 (b, 2OH) 2974, 2889 (2CH₂), 1646 (C=O), 1382 (P=N), 1240 (C-F), 1086 (C-S), 1046 (P-N), 879 (aryl CH), 755 (C-F). ¹H NMR (DMSO) δ 8.34 - 6.84 (18 aromatic protons), 4.8, 4.4 (each s, 2H, alcoholic 2OH) 2.62, 2.58 (each s, 4H, 2CH₂). ¹³C NMR (DMSO) = δ 179.86 - 179.68 (C=S), 163.07 (C=O), 159.62, 158.03 (C-F), (C-N), 138.60 (C=N), 132.121 - 107.94 (aromatic carbons), 77.75 77.32 (C5-C6 of 1,2,4-triazine), 40.57 - 40.46, 40.32 - 4.14 (2 CH₂).

2,4-Di(Piperidinomethyl)-6-(5’-fluoro-2’-triphenylphosphin-iminophenyl)-3-thioxo-1,2,-4-triazine-5-one (4)

A mixture of 2 (0.01 mol), piperidine (0.02 mol) and formaldehyde (0.02 mol) in methanol (50 ml) reflux for 2 h, cold. The solid produced filtered off and crystallized from MeOH to give 4 as yellow crystals. Yield = (60%) m.p. 179˚C - 180˚C. Analytical date found C = 67.41, H = 5.83, F = 2.55, N = 11.97, S = 4.33%. Calculated for C₃₉H₄₂FN₆OPS (692): C = 67.63, H = 12.13, F = 2.74, N = 12.13, S = 4.62%. IR νcm⁻¹ = 3062 (aromatic CH), 2936, 2840 (aliphatic CH₂), 1721 (C=O), 1538 (C=N), 1468 (deform CH₂), 1389) (P=N), 1248 (C-F), 1184 (C=S), 1049 (P-N), 885, 815, 754 (aryl CH), 709 (C-F). ¹H NMR (DMSO): δ 8.23 - 6.80 (18H, aromatic), 2.95, 2.92, 2.89 and 2.58 (CH₂ of piperdine, N-CH₂-N). ¹³C NMR (DMSO) = δ 172 (C=S), 154 (C=O), 147.25 (C-F), 137.54 (C=N), 116.10 - 108 (aromatic carbons), 77.80, 77.39 (C₅-C₆ of 1,2,4-triazine), 40 - 58, 40.47, 40.33, 40.19, 40.05 (CH₂ of piperidine) 39.91 - 39.63 (N-CH₂-N).

2,4-Di(4’-arylaminomethyl)-6-(5’-fluoro-2’-triphenylphosphiniminophenyl)-3-thioxo-1,2,4-triazine-5-

ones (5a & 5b)

A mixture of 2 (0.01 mol ) and formaldehyde (0.02 mol), 4-fluoroaniline and/or 4-aminoantipyrine (0.02 mol) in methanol (50 ml) warm under reflux for 2 h, then cold. The solid thus obtained, filtered off and crystallized from EtOH to give 5a & 5b as yellow crystals.

Compound 5a, yield (75%) m.p. 210˚C - 212˚C. Analytical data: Found C = 65.80, H = 4.11, F = 7.47, N = 10.89, S = 4.01%. Calculated for C₄₁H₃₂F₃N₆OPS (744), C = 66.12, H = 4.30; F = 7.66; N = 11.29, S = 4.30%. M/Z = 744 (M, 0, 0%), 370 (1), 367 (25), 290 (60), 272 (30), 248 (20), 218 (42), 169 (100), 128 (85), 102 (100), 65 (100). UV: (λ_max EtOH) 364 nm; IR νcm⁻¹ = 3343 (aryl-NH), 2974, 2889 (CH₂), 1650 (C = O), 1382 (P = N), 1250 (C-F), 1086 (C-S), 1045 (P-N) 879 (aryl CH). ¹H NMR (DMSO) = δ 12.71 (s, 1H, NH), 12.55 (s, 1H, NH), 7.41, 7.39, 7.32, 7.06, 7.01, 6.99, 6.98, 6.97, 6.91, 6.90 & 6.89, 6.88, 6.878, 6.873, 6.86 & 6.85, 6.84, 6.83, 6.77 & 6.768, 6.761, 6.754, 6.742, 6.735 (aromatic CH), 5.18 - 5.15 & 5.14 - 5.13 (4H, CH₂ of N CH₂-NH). ¹³C NMR = (DMSO) = δ 178.0 (C=S), 161.02 (C=O) 144.99 (C-F), 138.37 (C=N), 130.65 - 114.11 (aromatic car- bons) 77.57, 77.14 (C₅-C₆ of 1,2,4-triazine), 40.61 - 40.35, 39.94 - 39.66 (2N-CH₂-NH).

Compound 5b, yield (60%); m.p. 200˚C - 202˚C. Analytical data: Found C = 65.89, H = 4.91, F = 2.04, N = 14.83, S = 3.35%; Calculated for C₅₁H₄₆FN₁₀O₃PS (928), C = 65.94, H = 9.95, F = 2.04, N = 15.08, S = 3.44%. IR νcm⁻¹: 3277 (b, NH), 2974 (aliphatic CH₃) 2840 (CH₂), 1697, 1660 (2C=O), 1604 (C=N), 1542 (C=N), 1482 (deform, CH₂), 1416 (P=N), 1370 (NCSN), 1274 (C-F), 1152 (C-S), 1045 (P-N), 878, 810, 750 (aromatic CH), 650 (C-F). ¹H NMR (DMSO) δ 7.48 - 7.26 (aromatic CH) 5.07 (s, 1H, NH), 3.1 - 3.0 (s, 1H, NH), 2.99 - 2.88, 2.84 - 2.82 (2 CH₂), 2.62 - 2.41, 2.34 - 2.23, 2.229 - 2.2221, 2.16 - 2.07 (4 Me). ¹³C NMR = (DMSO) δ 179.81 (C=S) 159.11 (C=O), 142 (C-F), 138.0 (C=N), 129.38 - 123.31 (aromatic carbons), 77.54, 77.11 (C₅-C₆ of 1,2,4- triazin), 40.61 - 40.08 & 39.94 - 39.66 & 36.75 - 35.49 (N-CH₂), 18.42, 15.15 (N-Me, C-Me).

[6-(5’-Fluoro-2’-triphenylphosphiniminophenyl)-5-oxo-1,2,4-triazine-3-yl]thioacetic acid (6)

Equimolar mixture of 2 and monochloroacetic acid in DMF (20 ml) warm for 30/min, then poured onto ice. The solid yielded filtered off and crystallized form EtOH to give 6 as faint yellow crystals. Yield (80%), m.p. 187˚C - 188˚C. Analytical data: Found: C = 62.42, H = 3.81, F = 3.20, N = 9.85, S = 5.57%; Calculated for C₂₉H₂₂FN₄O₃PS (556). C = 62.58, H = 3.95, F = 3.41, N = 10.07, S = 5.75. IR νcm⁻¹ = 3327 (b, OH, NH), 2973, 2884 (CH₂), 1659 (b, 2 C=O), 1440 (deform CH₂), 1380 (P=N), 1250 (C-F), 1087 (C-S), 1045 (P-N) 880 (Ar CH), 810 (Ar CH). ¹H NMR (DMSO) δ = 10.31 (s, 1H, NH), 8.06, 8.0, 7.98 - 7.97, 79.86 - 7.84, 7.73, & 7.726, 7.721, 7.14, 7.08, 7.67 & 7.66, 7.65, 7.63, 7.53 - 7.51, 7.48 - 7.35 & 7.34, 6.997, 6.992, 6.838 - 6.824 (18 CH, aromatic) & 4.74 (s, 1H, OH of COOH), 3.86 - 3.24 (2H, CH₂). ¹³C NMR: (DMSO): δ 168.29 (C=S), 165.40 (C=O), 157.16 (C=O), 142.13 (C-F) 131.35 (C=N), 130.04 - 102.25 (aromatic carbons), 72.43, 72.22 (C₅-C₆ of 1,2,4-traizine), 34.95 - 34.81 (CH₂ carbon).

1,1-Di[6-(5’-Fluoro-2’-triphenylphosphiniminophenyl)-5-oxo-1,2,-4-triazine-3'yl]dimercaptoacetic acid (7)

A mixture of 2 (0.02 mol) and 1,1-dicholoracetic acid (0.01 mol) in DMF (20 ml) reflux for 30 min, cold then poured into ice. The resulted solid filtered off and crystallized from dioxin to give 7 as faint yellow crystals, yield (60%) m.p. 238˚C - 240˚C. Analytical data: Found C = 63.45, H = 3.49, F = 3.39, N = 10.39, S = 5.88%, Calculated for C₅₆H₄₀F₂N₈O₄P₂S₂ (1052) C = 63.87, H = 3.80, F = 3.61, N = 10.64, S = 6.08%. IR νcm⁻¹ = 3425, 3259, 3170 (OH, NH, NH), 1865, 1680 (C=O), 1618 (C=N), 1476, 1452 (aliphatic CH), 1360 (P=N), 1252 (C-F), 1193 (C-S), 1045 (P-N), 903, 859, 818, 758 (aryl CH) 685 (C-F). ¹H NMR (DMSO): δ 12.79, 12.78 (each s, 2NH), 10.75 (s, 1H, OH), 8.21 - 6.84 (18 CH, aromatic), 2.82 - 2.59 (s, 1H, CH) ¹³C NMR: δ 179.72 (C=S), 163 (C=O), 159 (C-S), 158.0 (C-S), 138.61 (C-F), 132.18 (C=N), 121.12 - 107.94 (aromatic carbons), 77.66, 77.45 (C₅-C₆) of 1,2,4-triazine), 40.57 - 40.46 (-CH-).

Tri[6-(5’-fluoro-2’-triphenxylphosphin-iminophenyl)-5-oxo-1,2,-4-triazine-3’yl]trimercaptoacetic acid (8)

A mixture of 2 (0.03 mol) and 1,1,1-trichloroacetic acid (0.01 mol) in DMF (20 ml) warm for 30 min then cold and poured on to ice. The produced solid filtered off and crystallized from Et OH to give 8 as reddish crys- tals. Yield (60%); m.p. 189˚C - 190˚C. Analytical data: Found C = 63.89, H = 3.45, F = 3.55 N, 10.67, S = 5.83%. Calculated for C₈₃H₅₈F₃N₁₂O₅P₃S₃ (1548); C = 64.34, H = 3.74, F = 3.68, N = 10.85, S = 6.2%. UV (λ_max EtOH) 359 nm. IR νcm⁻¹ = 3500 - 3100 (b, 3NH, OH) 1716 (C=O), 1624 (NH = OH of 1,2,4-triazinone) 1537 (C=N) 1471 (aliphatic CH). 1390 (P=N), 1300 (NCSN), 1260 (C-F), 1200 (C-S), 1645 (P-N), 920, 850, 780 (aryl CH), 650 (C-F). ¹H NMR (DMSO) = δ 12.95, 12.72, 12.33 (each s, 3H, NH), 10.84 (s, 1H, OH), 8.51, 8.23, 8.01, 7.92, 7.89, 7.71, 7.7, 7.69, 7.65, 7.63, 7.59, 7.58, 7.57 - 7.54, 7.50 - 7.47, 7.40 - 7.37, 7.33 - 7.31, 7.02 - 6.98, 6.86 - 6.83 (aromatic CH). ¹³C NMR = (DMSO) δ 179.61 (C=S), 163 (C=O), 159.5 (C-S), 157 (C-F) 138.58 (C=N), 137.79 (C=N), 132.91 (C=N), 131.99 - 107.93 (aromatic CH), 77.92, 77.49 (C₅-C₆ of 1,2,4-tria- zine).

6(5’-Fluoro-2’-triphenylphosphin-iminophenyl)2,-4-dihydro-thiazolo[3,2-b][1,2,4]triazine-3,7-dione (9)

Equimolar mixture of 2 and monochloroactic acid in DMF (20 ml) reflux for 2 h then cold and poured onto ice. The solid obtained filtered off and crystallized from dioxan to give 9 as brown ppt, Yield (60%) m.p. 224˚C. Compound 6 (0.50 mg) heat above its melting point (60˚C higher) for 10 min, cold then treat with MeOH. The solid produced filtered off and crystallized from dioxan to give 9 as brown ppt. Yield (58%), m.p. 225˚C - 227˚C. Analytical data Found C = 64.40, H = 3.51, F = 3.35, N = 9.93, S = 5.48% Calculated for C₂₉H₂₀FN₄O₂PS (538); C = 64.68, H = 3.71 F = 3.53, N = 10.40. S = 5.94%. UV: (λ_max EtOH) 352 nm. IR νcm⁻¹ = 3204 (b-OH), 1694 (C=O), 1623 (C=N), 15,636, 1475 (CH₂), 1380 (P=N), 12,999 (C-F), 1148 (C-S) 816, (aromatic CH), 711 (C-F). ¹H NMR (DMSO) = δ 10.79 (s, 1H, Phenolic OH), 8.23 (s, 1H, CH of thazole), 7.95 - 7.47, 7.35, 7.35, 6.98, 6.80 (aromatic CH). ¹³C NMR = (DMSO): δ 167.21 (C=S), 147.47, (C=O), 136.64 (C-F), 132.97 (C=N), 131.92 - 128.54, 118.80 - 118.14, 113.79 - 113.73 (aromatic carbons), 111.04 - 110.99 (-CH=), 77.80, 77.38 (C₅-C₆ of 1,2,4-triazine).

6(5’-Fluoro-2’-triphenylphosphiniminophenyl)-5-oxo-3-(cyanomethylthia)-2H-1,2,4-triazine (10)

A mixture of 2 (0.01 mol) and chloroacetinitrile (0.01 mol) in DMF (20 ml) warm (10 min) then cold and poured onto ice. The result solid filtered off and crystallized from dioxan to give 10 as faint Yellow crystals. Yield (70%); m.p. 214˚C - 215˚C. Analytical data: Found C = 64.39, H = 3.58, F = 3.11, N, 12.85, S = 5.75%. Calculated for C₂₉H₂₁FN₅OPS (537); C = 64.80, H = 3.91, F = 3.53, N = 13.03, S = 5.95%. M/Z = 537 (5%) 281 (20), 207 (60), 149 (20), 113 (30), 85 (100), 58 (100). UV: (λ_max EtOH) 321 nm. IR νcm⁻¹ = 3424, 3167 (NH, S-CH=C=NH) 2100 - 2085 (C≡N), 1646 (C=O), 1595 (C=N), 1481 (CH₂), 1370 (P-N), 967, 839, 762 (aryl CH), 700 (C-F). ¹H NMR (DMSO) = δ 13.90, (s, 1H, NH), 12.76 (s, 1H, HC=NH), 8.22 - 6.81 (aromatic CH), 4.69 (1H, HC=NH) 2.59 (2H, CH₂). ¹³C NMR (DMSO): δ 158.11 (C=O), 147.0 (C-F) 132 (C=N), 131.86 - 128.44 (aromatic carbons), 112.21 (C≡N), 77.96, 77.53 (C₅-C₆ of 1,2,4-triazine), 40.133 (-CH=NH), 33.63 (CH₂).

3-Amino-6(5’-fluoro-2’-triphenylphosphiniminophenyl)-thiazolo[3,2-b][1,2,4]triazine-7-one (11)

Compound 10 (0.5 gm) in DMF (20 ml) warm for 2 h then cooled and poured onto ice. The solid produced filtered off and crystallized from EtOH to give 11 as broom ppt, Yield (66%); m.p. 223˚C - 225˚C. Analytical data: Found C = 64.51 H = 3.38, F = 3.21 N = 12.55, S = 5.62%. Calculated for C₂₉H₂₁FN₅OPS (537), C = 64.80, H = 3.91, F = 3.53, N = 13.03, S = 5.95%. M/Z, 537 (2%), 370 (2), 226 (2), 168 (100), 140 (60), 114 (30), 62 (18), 70 (18). IR νcm⁻¹ = 3348, (b-NH₂), 16430 (C=O), 1383 (P=N), 1250 (C-F), 1086 (C-S), 1045 (P-N), 878 (aryl CH). ¹H NMR (DMSO) = δ 8.11 (s, 1H, = CH thiaszole), 7.72 - 7.011, 6.98 - 6.80 (aromatic CH), 3.99 - 3.84 (2H-NH₂). ¹³C NMR (DMSO) = 162.54 (C=O), 132.16 (C-F), 132.00 (C=N), 131.99 (C-S), 131.66 - 131.64 (=CH-), 128.61 - 120.55 (aromatic carbons), 77.59, 77.38 (C₅-C₆ of 1,2,4-triazine), 40.51 (-N-C=N).

3-(4’-Fluoro benzoyl)amino-6-(5’-fluoro-2’-triphenylphosphiniminophenyl)-thiazolo[3,2-b][1,2,4]

triazine-7-one (12)

Equimolar mixture of 11 and 4-fluorobenzoyl chloride in DMF (20 ml) warm for 10 min then cold and poured onto ice. The resulted solid filtered off and crystallized from EtOH to give 12 as deep-Yellowish crystals. Yield (75%). m.p. 205˚C - 207˚C. Analytical data: Found C = 65.19 H = 3.41, F = 5.49 N = 10.51, S = 4.59%. Calcu- lated for C₃₆H₂₅F₂N₅O₂PS (660), C = 65.55, H = 3.80, F = 5.76, N = 10.60, S = 4.80. IR νcm⁻¹ = 3342, (b-NH), 1651 (b, 2C=O), 1381 (P=N), 1326 (NCSN) 1230 (C-F), 1086 (C-S), 1045 (P-N), 879 (aryl CH). ¹H NMR (DMSO) = δ 13.70 (s, 1H, NH), 9.89 (s, = CH of thiazole) 8.411, 8.17, 8.07 - 8.05, 8.01, 7.99, 7.95, 7.79, 7.66 - 7.64, 7.44 - 7.42, 7.28, 7.27 (aromatic CH). ¹³C NMR = (DMSO): δ 167.53 (C=O), 162.54 (C=O) 138.59 (C-F) 132.25 (C-N), 132.19 (C=N), 129.33 - 127.27, 117.78 - 115.17, 112.15, 12.09, 110.52, 108.12, 107.95 (aromatic carbons), 77.64. 77.43 (C₅-C₆ of 1,2,4-triazine).

Schiff base (13)

Equimolar amounts of 11 and 4-fluorobenzaldehyde in absolute ethanol (20 ml) reflux for 30 min then cooled. The solid thus obtain filtered off and crystallized from EtOH to give 13 as Yellowish ppt. Yield (70%); m.p. 248˚C - 250˚C. Analytical data: Found C = 66.85, H = 3.61, F = 5.75 N = 10.59, S = 4.71%. Calculated for C₃₆H₂₄F₂N₅OPS (643), C = 67.18, H = 3.73, F = 5.90, N = 10.88, S = 4.97%. IR νcm⁻¹ = 3100, 2880 ( aromatic & aliphatic CH), 1700 (C=O), 1600 (C=N), 1483 (C-P), 1370 (P=N), 1230 (C-F), 1200 (C-S), 1045 (P-N), 880, 840, 810 (aryl CH), 650 (C-F) ¹H NMR (DMSO) = δ 9.97 (s, 1H, -CH=N-), 8.62 (s, 1H, -CH = thiazole) 8.23, 8.22, 8.09 - 8.00, 7.94 - 7.92, 7.71 - 7.63, 7.56 - 7.53, 7.49 - 7.45, 7.26 - 7.23, 7.12 - 7.10, 7.0 - 6.96, 6.89 - 6.84, 6.81 - 6.79 (aromatic CH).

6-(5’-Fluoro-2’-triphenyl phosphiniminophenyl)-3-oxo-3phenyl-thiazolo[3,2-b][1,2,4]triazine-7-one (14)

A mixture of 2 (0.01 mol) and phenacylbromide (0.01 mol) in ethanolic KOH, (20 ml, 5%) reflux for 2 h, cold then poured onto ice-HCl. The solid produced filtered off and crystallize from dioxan to give 14 as brown ppt. Yield (60%); m.p. > 300˚C. Analytical data: Found C = 69.88, H = 3.59, F = 3.01 N, 9.00, S = 5.13%, Calcu- lated for C₃₅H₂₄FN₄OPS (598); C = 70.23, H = 4.01, F = 3.17, N = 9.36 S = 5.35%. IR νcm⁻¹ = 3080, 3030 (aromatic CH), 1680 (C=O), 1380 (P=N), 1240 (C-F), 1180 (C-S), 1045 (P-N), 880, 850 (aryl CH).

Diaylthioether (16)

A mixture of 2 (0.01 mol) and Schiff base 15 (0.01 mol) in dry C₆H₆ (100/ml) reflux 8 h, cold and used peter- either 100˚C - 120˚C to complete precipitation. The solid obtained filtered off and crystallized dioxan to give 16 as Yellowish crystals. Yield (80%); m.p. 204˚C - 205˚C. Analytical data: Found C = 66.53, H = 4.31, F = 4.44, N = 11.88, S = 3.66%, Calculated for C₄₅H₃₆F₂N₇O₂PS (807); C = 66.91, H = 4.46, F = 4.70, N = 12.14, S = 3.96%. M/Z = (807.0.0), 580 (5), 515 (4), 462 (8), 423 (10), 370 (5), 339 (20), 282 (20), 225 (20), 207 (60), 176 (100), 149 (56), 119 (38), 85 (90), 58 (100). UV: (λ_max EtOH) 323 nm. IR νcm⁻¹ = 3332 (NH), 2973, 2886 (ali- phatic CH), 1636 (C = O), 1488 (CH₃), 1381 (P=N), 1324 (NCSN), 1250 (C-F), 1086 (C-S), 1045, (P-N), 880, 755 (aryl CH). ¹H NMR (DMSO) = δ 12.77, (s, 1H, NH), 10.75 (s, 1H, NH), 9.68 (s, 1H, S-CH-Ar), 8.23, 7.83 - 7.28, 7.27 - 7.00, 6.99 - 6.84 (aromatic CH), 3.69 (s, CH₃-N) 2.79 (s, CH₃-C).¹³C NMR (DMSO): δ 164.73 (C= O), 163.08 (C=O), 160.63, 155.18 (C-F), 151.9 (C-S), 134.64, 134.25, 134.23 (C=N), 129.487 - 115.492 (aro- matic carbons), 77.72, 77.50 (C₅-C₆ of 1,2,4-triazine), 67.00 (S-CH=NH), 39.95 - 39.81, 39.67 - 39.55 (2 CH₃).

2,3-Diaryl?2,3-dihydro-4-thioxo-7-(5’-fluoro-2’-triphenylphosphiniminophenyl)-1,3,5-thiazolo[3,2-b]

[1,2,4] triazine-8-one (17)

A mixture of 16 (0.01 mol) and CS₂ (5 ml) in DMF (20 ml) reflux for 4 h, cold then powered onto ice. The resultant solid filtered off and crystallized from dioxan to give 17 as yellowish crystals. Yield (75%), m.p. 254˚C - 255˚C. Analytical data: Found C = 64.88, H = 3.85, F = 4.38, N = 11.40, S = 7.45%, Calculated for C₄₆H₃₄F₂N₇O₂PS₂ (849); C = 65.01, H = 4.00, F = 4.47, N = 11.54, S = 7.53%; M/Z (849, 0.0%), 370 (2), 329 (40), 290 (100), 159 (100), 128 (100), 102 (100), 96 (100), 65 (100). UV: (λ_max EtOH) 34.7 nm. IR νcm⁻¹ = 2873 (aliphatic CH), 1684 (C=O), 1614. 1593 (C=N) 1475, 1425 (CH₃), 1318 (P=N), 1264 (C-F), 1199 (C=S), 1130 (C-S), 1052 (P-N), 985, 899, 854, 814, 732 (aryl CH). ¹³C NMR (DMSO) = δ 179.70 (C=S), 163.07 (C=O), 155.08 (C-F), 138.62 (C=N, 1,2,4-triazine), 132.23, 132.13 (C=C pyrazole), 129.43 - 115.44, 112.09 - 107.96 (aromatic carbons), 77.71, 77.28 (C₅-C₆ of 1,2,4-triazine) 66.94 (S-CH-NH), 40.57, 39.76 (2 CH₃).

Di-Heteroaryldisulfide (18)

Compound 2 (0.05 gm) and FeCl₃ (0.5 gm) in MeOH (20 ml) reflux for 3 h, then filtered. The solid produced filtered off and crystallized from dioxan to give 18 as deep-yellowish crystals. Yield (80%), m.p. 238˚C - 240˚C. Analytical data: Found C = 64.85, H = 10.89, F = 3.55, N = 10.89, S = 6.22%. Calculated for C₅₄H₃₈F₂N₈O₂P₂S₂ (994); C = 65.19, H = 11.26, F = 3.82, N = 11.26, S = 6.43%. IR νcm⁻¹ = 3300, 3200 (NH, NH), 1680 (C=O), 1600 (C=N), 1350 (P=N), 1100 (C-S), 1040 (P-N), 900, 850, 800 (aryl CH), 650 (C-F). ¹H NMR (DMSO) = δ 14.55, 12.78 (each s, 2H, NH, NH), 8.20 - 6.85 (aromatic CH). ¹³C CNMR (DMSO): δ 179.90, 179.74 (2C-S), 159 - 66, 158.66 (2C=O), 138.63 (C-F), 132.18 (C=N), 121.12 - 107.95 (aromatic carbons), 77.65, 77.43 (C₅-C₆ of 1,2,4-triazine).

6-(5’-Fluoro-2’-triphenylphosphiniminophenyl)-5-oxo-2H-1,2,4-triazine-3-sulfonic acid (19)

Compound 2 (0.05 gm) in ethanol (10 ml) and H₂O₂, (0.5 ml) add with stirring for 2 h. The solid obtained fil- tered off and crystallized from EtOH to give 19 as yellowish crystals yield (75%); m.p. 258˚C - 260˚C. Analyti- cal data: Found C = 59.00, H = 3.44, F = 3.25, N = 9.87, S = 5.45%. Calculated for C₂₇H₂₀FN₄O₄PS (546), C = 59.34, H = 3.66, F = 3.47, N = 10.25, S = 5.86%. IR νcm⁻¹ = 3300 (NH), 1696 (C=O), 1390 (NCSN), 1360 (P=N), 879, 820, 780, (aryl CH). 670 (C-F). ¹H NMR (DMSO) = δ 12.79 (s, 1H, NH), 10.72 (s, 1H, SO₂-OH), 8.13 - 6.76 (aromatic CH). ¹³C NMR (DMSO): δ 179.75 (-S=O), 163.09 (C=O), 159.67 (C-F), 138.62 (C=N), 132.23 (C-S), 121.08 - 107.95 (aromatic carbons), 77.60, 77.39 (C₅-C₆ of 1,2,4-triazine).

6-(5’-Fluoro-2’-triphenylphosphiniminophenyl)-1,2,4-triazine-3,5-(2H, 4H)dione (20)

Compound 2 (0.05 gm) in ethanol (10 ml) and KMnO₄ solution (ethanolic 1%, 1 ml) add drop wise then stirr- ing for 2 h. The produced solid filtered off and crystallized from Et OH to give 20 as yellowish crystals yield (50%); m.p. 273˚C - 275˚C. Analytical data: Found C = 66.89, H = 4.01, N = 11.35, F = 3.55. Calculated for C₂₇H₂₀FN₄O₂P (482), C = 67.21, H = 4.14, N = 11.61, F = 3.94. M/Z: (482, 0.0%), 370 (10), 206 (101, 148, (16), 128 (24), 110 (35), 96 (55), 83 (78), 68 (100). IR νcm⁻¹ = 3426, 3259, 3170 (OH, NH, NH), 1766, 1681 (2C=O), 1619 (C=N) 1452 (C-P) 1301 (P=N), 1252, (C-F) 1048 (P-N), 905, 861, 820, 802, 784, 761 (CH), 687 (C-F), ¹H NMR (DMSO) = δ 12.73, 10.82 (each s, NH, OH), 7.88 - 6.84 (aromatic CH). ¹³C NMR = δ 153.58 (C=O), 152.78 (C=O), 147.84 (C-F). 132.58 (C=N) 130.51 - 111. (Aromatic carbons), 77.85, 77.60 (C₅-C₆ of 1,2,4-tri- azine).

3. Results and Discussion

3.1. Chemistry

A recent work on the synthesis and chemistry of bioactive sulfur bearing 1,2,4-triazinone moiety was reported [16] [19] . In continuation of this attitude the present investigation reports the synthesis of fluorine and phospho- rus-substituted 6-amino-phenyl-3-thioxo-1,2,4-triazin-5-(2H, 4H) one (1) and study that behavior towards vari- ous alkylating agents. Treatment of 5-fluoroisatin with thiosemicarbozide in alkaline medium [14] [15] pro- duced 6-(2’-amino-5’-fluorophenyl-3-thioxo-1,2,4-triazin-5-(2H’4H) one (1). Warm compound 1 with triphe- nylphosphine in acetonitrile produced the yield 2 (Scheme 1).

In the imino [yield, 2] a negative charge of nitrogen is bonded to positive charge of phosphorus stabilized by partial overlap of the filled N-P orbital. This stabilization increase due to the charge on the α-carbon atom is spread by 1,2,4-triazine resonance. Abdel-Rahman [14] [15] reported that N-alkyl of 3-thioxo-1,2,4-triazinones exhibited a wide biological spectrum anti HIV and anticancer properties. Similarly, hydroxyl methylation of compound 2 by boil with formaldehyde-methanolproduced 2,4-di(hydroxylmethyl)-6-(5’fluoro-2’-triphenylphos- phiniminophenyl)-3-thioxo-1,2,4-triazin-5-one (3). Also, reflux of compound 2 with secondary and primary amines such as piper dine, 4-fluoroaniline and 4-amino-antipyrine in the presence of formaldehyde methanol, furnished the Mannich bases 4 and 5 (Scheme 2).

Formation of 3 and 4 was may be as (Figure 1).

Due to a higher nucleophilicity of sulfur atoms, the direct displacement of an acidic proton of mercapto group by a simple electrophile can be easily occur via treatment of compound 2 with haloacetic acids. Thus treatment of compound 2 with halo aliphatic acids such as mono/di/trichloroacetic acids in DMF afforded the substituted thiaacetic acids 6-8 (Scheme 3).

The multicomponent reaction (MCR) was considered as powerful synthetic tool for preparing target mole- cules of biological relevance in an efficient manner. Thus, treatment of compound 2 with active methylene rea- gents as chloroacetonitrile in warm DMF [20] produced 3-cyanomethyl thai-6-iminophosphorane-1,2,4-trinazin- 5-(2H)one (10). The latter compound 10 use for the synthesis of thiazolo [3,2-b][1,2,4]triazinones (11-13) sys- tems (Scheme 4). Acidic hydrolysis of 10 by warm with diluted HCl for short time (10 min) yielded the com- pound 6. Boil compound 6 with DMF along time afforded 6-iminophosphorane-2,3-dihydoro-thiazolo [3,2-b] [1,2,4] triazine-3,7-dione (9) (Scheme 4).

Heat compound 10 on heating with DMF a long time (2 hours), produced 3-aminothiazolo-1,2,4-triazine 11. Presence of an amino group in structure 11 was deduced from treat with 4-fluorobenzoylchloride (DMF) and/or with 4-fluorobenzaldehyde (EtOH) yield the anilido 12 and/or Schiff's base 13 (Scheme 4). Treatment of com- pound 2 with α, β-bifunctional oxygen-halogen reagents as phenacyl bromide in ethanolic KOH, yielded 3- phenyl-6-iminophosphorane-thiazolo [3,2-b][1,2,4]triazin-7-one (14) (Scheme 5). The nitrogen-sulfur contain- ing fused heterobicyclic structures have demonstrated a high degree of binding affinity when they serve as Ligands for various biological receptors [12] [13] . Thus addition of Mercator group (as nucleophilic) of compound 2 to an Schiff’s base 15 in boil dry dioxan yielded the thioether16, which upon ring closure reaction by reflux with CS₂ in DMF furnished 2,3-diaryl-2,3-dihydro-7-iminophosphorane-4-thioxo-1,3,5-thiadiazino[3,2-b]

[1,2,4]-triazin-8-one (17) (Scheme 5).

Abdel-Rahman et al. [21] -[25] reported that thioethers, sulfide and sulfonic acid bearing a 1,2,4-triazine moieties. Exhibited a very interesting medicinal activity as anti-HIV and anticancer agents. Recently, Slawinski et al. [25] synthesized 2-mercaptobenzene sulfonamide bearing a 1,2,4-trinzines exhibited a significant activity against cell lines of colon cancer, renal cancer, and melanoma, as well as good selectivity toward non-small cell lung cancer. Similarly, oxidation of compound 2 via treatment with FeCl₃ in boiling methanol and/or with H₂O₂ in ethanol by stirred at room temperature furnished the disulfide 18 and/or 3-sulfonic-1,2,4-triazinone 19. Final- ly, treatment of 2 with ethanolic KMnO₄ at room temperature [21] led to the direct formation of 6-(5’-fluoro- 2-triphenylphosphiniminophenyl)-1,2,4-triazin-3,5(2H, 4H)dione (20) (Scheme 5).

3.2. Elucidation the Former Structures

3.2.1. UV Spectra

The electronic conjugated molecule of compound 2 exhibited λ_max at 310 nm while that of compounds 3 (363), 5a (364), 8 (359) and 16 (323) nm. A higher absorption bands of new acyclic systems than that of 2 confirm that N- and S-substitution were formed. On the other hand, the absorption bands of fused heterobicycle compounds 9 (352), 17 (347) and 10 (321) nm is higher than the start 2 (310) nm. This is attributing to extension of hetero- conjugation of heterobicylic systems through a type of cylization.

3.2.2. IR Spectra

The new compounds obtained recorded the absorption bands at 1380 - 1390, 1250 - 1230 cm⁻¹ due to presence of both P=N and C-F functional groups. Compounds 3-5 showed a lack of band at 3200 - 3100 cm⁻¹ for NH=OH of 1,2,4-triazinones, while that of compounds 6-8 and 10 recorded the absorption band at 3343 and 1643 cm⁻¹ attributed to presence of ⁴NH & ⁵C=O of 1,2,4-triazinone. Only compounds 9-14 showed a lack of the absorp- tion bands at 1200 - 1100 cm⁻¹ for C=S, which confirm that heterocyclization. In addition to the compounds 6-9 & 18, 20 exhibited a two absorption bands at ν 1700 and 1665 cm⁻¹ due to the presence of two carbonyl groups. Also, IR absorption spectra of compounds 3-8, 9-10 and 16 recorded the absorption bands at ν 2975 and 2885 cm⁻¹ attributed to aliphatic functional groups [1] [14] [15] [26] .

3.2.3. NMR Spectral Study

1) ¹H NMR spectrum of 1 showed a resonated signals at δ 14.6, 12.6 and 10.9 ppm for 3NH with δ 8.6 - 0.80, 7.69 - 7.64, 7.41 - 7.31 ppm for three aromatic protons, while that of 3 exhibited a signals at δ 5.24 and 4.98 ppm attributed to two OH with δ 2.92 - 2.88, 2.62 - 2.58 ppm for two CH₂ protons. Compounds 3, 4 and 5 showed a lack’s of ⁴NH and ²NH of 1,2,4-triazine moiety, while that of 5 recorded additional signals at δ 1.9 and 1.75 ppm of two methyl groups of antipyrine moiety. ¹H NMR spectra of 6-8 recorded δ at 12.7, 4.7 ppm for NH and OH protons, while that of 9 showed a signal at δ 10.5 and 8.5 ppm, attributed to OH and CH = of thiazole moiety. In addition to compound 10 recorded a signals at δ 13.90, 2.59 ppm for NH, CH₂ protons, while that of

11 exhibited only signals at δ 8.01 and 3.99 ppm for = CH thiazole and amino-protons. Moreover ¹H NMR spectrum of 16 showed a signals at δ 12.76 and 10.75 ppm for two NH of 1,2,4 trinazine while a lacks of these (2NH) protons of 17, with presence of CH proton of thiadiazine moiety at δ 9.68 ppm. ¹H NMR spectra of compounds 18 recorded the presence of δ at 14.55 and 12.79 ppm attributed to 2NH of 1,2,4-triazine protons, while that of 19 exhibited a signals at δ 12.8 and 10.7 p pm for NH and CH. (SO₂-OH) protons, with signals of aromatic protons. Finally, compound 20 exhibited δ at 12.73 and 10.82 ppm attributed to NH and OH protons [14] [15] [19] [26] .

2) ¹³C NMR spectra of all the synthesized compounds showed a resonated signals at δ 180, 165 - 163, 140 - 138, 135 - 121 and 112 p pm attributed to C=S, C=O, C=N, aromatic and C-F carbons. Also, ¹³C NMR spectra of compounds 3-6, 9 and 10 recorded signals at δ 39 - 33 ppm for CH₂ carbons. Only the compound 10 showed an additional signal at δ 112 p pm for C≡N carbon. Finally, ¹³C NMR spectra of the entire compound exhibited a resonated signals at 77 - 75 ppm for C5-C6 of 1,2,4-triazine [27] (Figure 2).

3) ¹⁹F NMR spectral study recorded a signal at δ −126 to −125 ppm.

4) ³¹P NMR spectral study exhibited a signal at δ 30 - 29 p pm attributed to P=N [17] .

3.2.4. Mass Fragmentation Study

Mass fragmentation pattern study of some selective synthesized compounds indicated that fused heterobiycyclic systems 11 have a more base peak, while that of acyclic structures 1and 16 have only base peak which indicate that their less stability. A higher stability of fused heterobicyclic systems is due to the delocalization of net charge over all the active centers (Figure 3 to Figure 5).

4. Molluscicidal Activity

Based upon the earlier work by Abdel-Rahman et al. [7] [16] on the synthesis of phosphono substituted-1,2,4-

triazine derivative and their molluscicdal activities against Biomophalaria Alexandrina Snails responsible for Bilharziasis diseases, the prepared compounds were tested as killing of that snails ( shell in diameter 5 - 8). The intermediate host of sohistosomamausoni in Giza Govern state that was not treated with molluscicides. The snails were adapted to laboratory conditions for two weeks before being used in toxicity tests to be sure that the snails are strong and healthy. Snails were kept in plastic aguaria filled with de chlorinated tap water at room temperature (25˚C - 27˚C). Stock solution (500 μg∙ml⁻¹) of the tested compounds were synthesized in the least volume of ethanol and completed of the least volume of ethanol and completed to the required volume with de chlorinated tap water on the basis of weight volume. A series of more diluted solutions were then prepared fol- lowing the instructions given by WHO organization [28] [29] . The result given in (Table 1) revealed that the high activity towards snails in the following sequences:

18 > 2 > 20 > 3 > 8 and 9 > 10 > 6 > 17 >> 5a and 5b > 7 > 14 at 100 ppm in compared with Baylucide as

standard reference. In general, the strong effect of the compounds 2, 3, 8, 18 and 20 is due to presence both the S-S, S-H and O-H functional groups which agree with bio-oxidation-reduction processes. The moderate effect of the compounds 5a, 6, 9, 10 and 17 is attributed to thioether and cyclic sulfur nitrogen systems. Finally, the lethal effect of the compounds 4, 5b, 7, 11 and 14 may be to absence of SH and/or OH of Mannich base and for thia- zolotriazine systems which led to the inhibition of delocalization electron-density over all the center of systems. Also, presence of hetero-elements (F, P, S, O) and N elements in corporated with 1,2,4-trinazines led to increas- es of electro-negativity, over all the molecular structure and enhance the electrostatic force and hydrophobic properties [17] [18] [31] -[33] . Thus, total electron-barrier of molecular distribution of the evaluated systems synthesized led to highly inhibition of the enzymatic effect on the living processes for the tested snails by causing break of a vital cyclic of that snails, and enhance the possibility killing of these snails. QSAR study of the obtained resulted from (Table 1), and based on the introduction of P, S and F in the synthesized 1,2,4-triazines, in compared with the mortality of tested snails, indicated that, increases of P and S percent % led to increase of mortality, while, increase of F percentage % led to decrease of mortality of snails. Also, very high electronegative of fluorine atom can modify the electronic distribution in the molecule affecting its absorption distribution and metabolism. In conclusion, 3-thioxo-1,2,4-triazine-5-ones bearing an P, S and F elements and their related S-alkyl derivatives, enhance the mortality of snails, which cause Bilharziasis Diseases than that their non-fluo- rinated and non-phosphinated systems. Also, increases of P and S percentage % led to higher mortality of the tested snails, in hope to obtain more clean water from waste water.

5. Conclusion

New fluorine substituted 6-(5’-fluoro-2’-triphenylphosphiniminophenyl) 3-thioxo-1,2,4-triazin-5 (2H, 4H) one (2) was obtained via Wittig’s reaction of the corresponding 6-(5’-fluoro-2’-aminophenyl)-3-thioxo-1,2,4-triazinone (1). 3-thioxo-1,2,4-triazine-5-ones bearing an P, S and F elements and their related S-alkyl derivatives, enhance the mortality of snails, which cause Bilharziasis Diseases than that their non-fluorinated and non-phosphinated systems. Also, increases of P and S percentage % led to higher mortality of the tested snails, in hope to obtain more clean water from waste water.

Acknowledgements

The authors are thankful to Prof. M. M. El-Sayed for helping in testing the molluscicidal activity in Theodor Bilharz Research institute, Giza, Egypt.

References

NOTES

^*Corresponding author.