Facile synthesis and antimicrobial evaluation of some new heterocyclic compounds incorporating a biologically active sulfamoyl moiety.

A facile and convenient synthesis of new heterocyclic compounds containing a sulfamoyl moiety suitable for use as antimicrobial agents was reported. The precursor 3-oxo-3-phenyl-N-(4-sulfamoylphenyl)propionamide was coupled smoothly with arenediazonium salt producing hydrazones which reacted with malononitrile or triethylorthoformate affording pyridazine and triazine derivatives, respectively. Also, the reactivity of the same precursor with DMF-DMA was followed by aminotriazole; aromatic aldehydes was followed by hydrazine hydrate, triethylorthoformate, or thiourea affording triazolo[1,5-a]pyrimidine, pyrazole, acrylamide, and dihydropyrimidine derivatives, respectively. On the other hand, treatment of the precursor propionamide with phenyl isothiocyanate and KOH in DMF afforded the intermediate salt which was treated with dilute HCl followed by 2-bromo-1-phenylethanone affording carboxamide derivative. While the same intermediate salt reacted in situ with chloroacetone, ethyl 2-chloroacetate, 3-(2-bromoacetyl)-2H-chromen-2-one, methyl iodide, or 2-oxo-N-phenylpropane hydrazonoyl chloride afforded the thiophene, ketene N,S-acetal, and thiadiazole derivatives, respectively. The structure of the new products was established based on elemental and spectral analysis. Antimicrobial evaluation of some selected examples from the synthesized products was carried out whereby four compounds were found to have moderate activities and one compound showed the highest activity.

1. Introduction

Sulfonamides have been reported to exhibit antimicrobial [1-3], antifungal [4], insulin releasing [5], carbonic anhydrase inhibitory [6], anti-inflammatory [7], and antitumor [8], properties. Some active sulfonamides as antibacterial are also known for their immune modifying effects [9]. Also, pyrazole derivatives are known to exhibit diverse bioactivities such as antidepressant [10], anticonvulsant [11], antimicrobial [12], analgesic [13], and antitumor [14] activity and also serve as human acyl-CoA: cholesterol acyltransferase inhibitors [15]. In addition, thiophene compounds are well known to exhibit various biological and medicinal activities such as BACEI inhibitors [16], antitubercular [17], antidepressant [18], anti-inflammatory [19], and anti-HIV PR inhibitors [20], and antibreast cancer activities [21]. These facts, coupled with our desire to develop efficacious antimicrobial agents, and in continuation of our work in heterocycles of biological interest [22-25], prompted us to devise an efficient and convenient method of synthesis of hitherto unknown and novel hydrazone, pyridazine, acrylamide, pyrazole, triazolo[1,5-a]pyrimidine, thiadiazole, dihydropyrimidine, and thiophene derivatives with a sulfonamide nucleus. Results from assessment of the antimicrobial activity of these newly synthesized compounds are reported in this study.

2. Experimental Part

All melting points were determined on an electrothermal Gallenkamp apparatus and are uncorrected. The IR spectra were measured on a Pye-Unicam SP300 instrument in potassium bromide discs. The 1H-NMR spectra were recorded on a Varian Mercury VXR-300 spectrometer (300 MHz). The mass spectra were recorded on a GCMS-Q1000-EX Shimadzu and GCMS 5988-A HP spectrometers; the ionizing voltage was 70 eV. Elemental analyses were carried out by the Microanalytical Center of Cairo University, Giza, Egypt. The biological evaluation of the products 3a, 3c, 6, 7, 8b, 10, 15, 16, and 17 was carried out at the Medical Mycology Laboratory of the Regional Center for Mycology and Biotechnology of Al-Azhar University, Cairo, Egypt.

3-Oxo-3-phenyl-N-(4-sulfamoylphenyl)propionamide (1) and 3-(2-bromoacetyl)-2H-chromen-2-one [26-29] were prepared as previously described.

2.1. Coupling of 3-Oxo-3-phenyl-N-(4-sulfamoylphenyl)propionamide (1) with the Appropriate Diazonium Salt of Aromatic Amines

General Procedure. To a cold solution of 3-oxo-3-phenyl-N-(4-sulfamoylphenyl)propionamide (1) (0.318 g, 1 mmol) in pyridine (20 mL), the appropriate diazonium salt of aromatic amine (aniline or 4-methylaniline or 4-chloroaniline or 4-methoxy-aniline or 4-nitroaniline) (1 mmol) was added (prepared according to literature procedures) [30]. The addition was carried out portionwise with stirring at 0–5°C over a period of 30 min. After complete addition, the reaction mixture was stirred for further 4 hrs, then kept in an ice chest for 12 hrs, and finally diluted with water. The precipitated solid was collected by filtration, washed with water, dried, and finally recrystallized from the proper solvent to afford the corresponding coupling products 3a–e.

2.2. 2-[(4-Methoxyphenyl)hydrazono]-3-oxo-3-phenyl-N-(4-sulfamoylphenyl)propionamide (3a)

Yield (80%), m.p. 270°C (dioxane); IR (KBr) ν max⁡: 3351, 3264 (NH, NH2), 3073 (aromatic CH), 1657 (C=O) cm−1; 1H NMR (DMSO-d6): δ 3.75 (s, 3H, OCH3), 6.96 (d, 2H, J = 9 Hz), 7.28 (d, 2H, J = 9 Hz), 7.30 (s, 2H, D2O-exchangeable NH2), 7.61 (d, 2H, J = 8 Hz), 7.77 (d, 2H, J = 8 Hz), 7.79–7.93 (m, 5H, Ar-H), 11.47 (s, 1H, D2O-exchangeable NH), 13.82 (s, 1H, D2O-exchangeable NH); MS m/z (%): 452 (M++2, 3.33), 452 (M+, 18.37), 347 (4.07), 252 (15.66), 196 (3.51), 172 (5.49), 105 (100.0). Anal. Calcd for C22H20N4O5S (452.49): C, 58.40; H, 4.46; N, 12.38; S, 7.09. Found: C, 58.36; H, 4.36; N, 12.32; S, 7.01%.

2.3. 2-(p-Tolylhydrazono)-3-oxo-3-phenyl-N-(4-sulfamoylphenyl)propionamide (3b)

Yield (75%), m.p. 280°C (dioxane); IR (KBr) ν max⁡: 3352, 3265 (NH, NH2), 2924, 2858 (aliphatic CH), 1660 (C=O) cm−1; 1H NMR (DMSO-d6): δ 2.26 (s, 3H, CH3), 7.14 (s, 2H, D2O-exchangeable NH2), 7.17–7.30 (m, 5H, Ar-H), 7.56 (d, 2H, J = 9 Hz), 7.62 (d, 2H, J = 9 Hz), 7.81 (d, 2H, J = 8 Hz), 7.93 (d, 2H, J = 8 Hz), 11.37 (s, 1H, D2O-exchangeable NH), 13.55 (s, 1H, D2O-exchangeable NH); MS m/z (%): 437 (M++1, 25.12), 436 (M+, 35.75), 332 (26.57), 329 (32.85), 279 (51.21), 263 (33.82), 171 (42.03), 157 (31.40), 104 (28.02), 57 (100.0). Anal. Calcd for C22H20N4O4S (436.49): C, 60.54; H, 4.62; N, 12.84; S, 7.35. Found: C, 60.50; H, 4.55; N, 12.72; S, 7.27%.

2.4. 2-(Phenylhydrazono)-3-oxo-3-phenyl-N-(4-sulfamoylphenyl)propionamide (3c)

Yield (70%), m.p. 282°C (dioxane); IR (KBr) ν max⁡: 3349, 3256 (NH, NH2), 3059 (aromatic CH), 1650 (C=O) cm−1; 1H NMR (DMSO-d6): δ 7.18 (s, 2H, D2O-exchangeable NH2), 7.20–7.66 (m, 5H, Ar-H), 7.70 (d, 2H, J = 9 Hz), 7.76 (d, 2H, J = 9 Hz), 7.85–8.00 (m, 5H, Ar-H), 11.59 (s, 1H, D2O-exchangeable NH), 13.46 (s, 1H, D2O-exchangeable NH); MS m/z (%): 422 (M+, 7.6), 223 (1.9), 199 (0.4), 171 (1.8), 121 (20.3), 119 (3.0), 105 (100.0), 77 (57.7). Anal. Calcd for C21H18N4O4S (422.47): C, 59.71; H, 4.29; N, 13.26; S, 7.59. Found: C, 59.66; H, 4.26; N, 13.30; S, 7.53%.

2.5. 2-[(4-Chlorophenyl)hydrazono]-3-oxo-3-phenyl-N-(4-sulfamoylphenyl)propionamide (3d)

Yield (60%), m.p. 304°C (dioxane); IR (KBr) ν max⁡: 3364, 3262 and 3152 (NH, NH2), 1660 (C=O) cm−1; 1H NMR (DMSO-d6): δ 7.24 (s, 2H, D2O-exchangeable NH2), 7.52 (d, 2H, J = 8 Hz), 7.62 (d, 2H, J = 8 Hz), 7.64 (d, 2H, J = 9 Hz), 7.83 (d, 2H, J = 9 Hz), 7.85–7.93 (m, 5H, Ar-H), 11.21 (s, 1H, D2O-exchangeable NH), 13.05 (s, 1H, D2O-exchangeable NH); MS m/z (%): 457 (M++1, 13.25), 456 (M+, 16.64), 329 (8.10), 285 (11.19), 199 (10.90), 128 (11.49), 105 (100.0). Anal. Calcd for C21H17ClN4O4S (456.91): C, 55.20; H, 3.75; Cl, 7.76; N, 12.26; S, 7.02. Found: C, 55.15; H, 3.66; Cl, 7.66; N, 12.21; S, 7.00%.

2.6. 2-[(4-Nitrophenyl)hydrazono]-3-oxo-3-phenyl-N-(4-sulfamoylphenyl)propionamide (3e)

Yield (55%), m.p. 302°C (dioxane); IR (KBr) ν max⁡: 3368, 3265 and 3161 (NH, NH2), 1664 (C=O) cm−1; 1H NMR (DMSO-d6): δ 7.26 (s, 2H, D2O-exchangeable NH2), 7.59 (d, 2H, J = 9 Hz), 7.70 (d, 2H, J = 9 Hz), 7.78–7.89 (m, 5H, Ar-H), 7.91 (d, 2H, J = 8 Hz), 8.20 (d, 2H, J = 8 Hz), 11.08 (s, 1H, D2O-exchangeable NH), 12.45 (s, 1H, D2O-exchangeable NH); MS m/z (%):468 (M++1, 3.89), 467 (M+, 7.25), 362 (4.71), 296 (4.26), 199 (4.33), 172 (19.88), 105 (100.0). Anal. Calcd for C21H17N5O6S (467.46): C, 53.96; H, 3.67; N, 14.98; S, 6.86. Found: C, 53.87; H, 3.59; N, 14.88; S, 6.78%.

2.7. N-[4-(Aminosulfonyl)phenyl]-5-cyano-6-imino-4-phenyl-p-tolyl-1,6-dihydropyridazine-3-carboxamide (4)

To a solution of (3b) (0.436 g, 1 mmol) and malononitrile (1 mmol) in dioxane (20 mL), few drops of piperidine were added and the reaction mixture was refluxed for 6 hrs. The solid product that formed was filtered off, washed with ethanol, and then recrystallized from the proper solvent to give 4.

Yield (55%), m.p. > 300°C (DMF); IR (KBr) ν max⁡: 3462, 3305 and 3181 (NH, NH2), 2203 (C≡N), 1637 (C=O) cm−1; 1H NMR (DMSO-d6): δ 2.49 (s, 3H, CH3), 7.32 (d, 2H D2O-exchangeable NH2), 7.40 (d, 2H, J = 8 Hz), 7.59 (d, 2H, J = 9 Hz), 7.67–7.90 (m, 9H, Ar-H), 11.20 (s, 1H, D2O-exchangeable NH), 14.60 (s, 1H, D2O-exchangeable NH); MS m/z (%): 484 (M+, 2.32), 409 (7.42), 393 (9.09), 313 (6.94), 285 (6.58), 199 (7.89), 91 (16.51), 77 (26.56), 69 (100.0). Anal. Calcd for C25H20N6O3S (484.54): C, 61.97; H, 4.16; N, 17.34; S, 6.62. Found: C, 61.92; H, 4.11; N, 17.30; S, 6.59%.

2.8. 4-(6-Benzoyl-3-ethoxy-5-oxo-2-p-tolyl-2,3-dihydro-1,2,4-triazin-4-(5H)-yl)benzenesulfonamide (5)

To a solution of the compound 3b (0.436 g, 1 mmol) in acetic acid (20 mL), triethyl orthoformate (0.2 mL, 1 mmol) was added and the reaction mixture was refluxed for 8 hrs; then it was left to cool. So the solid product formed was filtered off, washed with EtOH, and dried. Recrystallization from dioxane afforded 4-(6-benzoyl-3-ethoxy-5-oxo-2-p-tolyl-2,3-dihydro-1,2,4-triazin-4-(5H)-yl)benzenesulfonamide (5).

Yield (50%), m.p. 296°C (DMF); IR (KBr) ν max⁡: 3370, 3311 and 3236 (NH, NH2), 3056 (aromatic CH), 2982 (aliphatic-H), 1678 (C=O) cm−1; 1H NMR (DMSO-d6): δ 1.32 (t, 3H, J = 7.2 Hz, CH3), 2.24 (s, 3H, CH3), 4.27 (q, 2H, J = 7.2, CH2), 5.94 (S, 1H), 7.36 (s, 2H, D2O-exchangeable NH2), 7.37–7.57 (m, 9H, Ar-H), 7.60 (d, 2H, J = 9 Hz), 7.71 (d, 2H, J = 9 Hz); MS m/z (%): 494 (M++2, 0.1), 492 (M+, 0.5), 352 (0.42), 335 (1.6), 156 (0.6), 105 (100.0), 91 (1.5). Anal. Calcd for C25H24N4O5S (492.56): C, 60.96; H, 4.91; N, 11.37; S, 6.51. Found: C, 60.88; H, 4.85; N, 11.31; S, 6.50%.

2.9. 2-Benzoyl-3-dimethylamino-N-(4-sulfamoylphenyl)acrylamide (6)

A mixture of the compound 1 (3.18 g, 10 mmol) and N,N-dimethylformamide dimethyl acetal (DMF-DMA) (10 mmol) in dry dioxane (30 mL) was refluxed for 6 hrs; then it was left to cool at room temperature. The yellow precipitated product was filtered off, washed with petroleum ether, and dried. Crystallization from MeOH was carried out to give 2-benzoyl-3-dimethylamino-N-(4-sulfamoylphenyl)acryl-amide (6) in 44% yield.

Yield (44%), m.p. 190°C (MeOH); IR (KBr) ν max⁡: 3250, 3112 (NH, NH2), 3056 (aromatic CH), 1683 (C=O), cm−1; 1H NMR (DMSO-d6): δ 3.42 (s, 6H, 2CH3), 6.62 (d, 2H, J = 9 Hz), 7.03 (s, 2H, D2O-exchangeable NH2), 7.28–7.31 (m, 5H, Ar-H), 7.58 (d, 2H, J = 9 Hz), 8.10 (s, 1H, olefinic-H), 9.98 (s, 1H, D2O-exchangeable NH); MS m/z (%): 373 (M+, 0.4), 291 (1.1), 190 (0.5), 155 (16.3), 105 (100.0). Anal. Calcd for C18H19N3O4S (373.43): C, 57.90; H, 5.13; N, 11.25; S, 8.59. Found: C, 57.89; H, 5.03; N, 11.15; S, 8.61%.

2.10. 5-Phenyl-[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylic Acid (4-sulfamoylphenyl)amide (7)

To a solution of the compound 6 (0.37 g, 1 mmol) in acetic acid (20 mL), amino triazolo (0.1 g, 1 mmol) was added and the reaction mixture was refluxed for 8 hrs; then it was left to cool. The solid product formed was filtered off, washed with EtOH, and dried. Recrystallization from dioxane afforded 5-phenyl-[1,2,4]triazolo[1,5-a]-pyrimidine-6-carboxylic acid(4-sulfamoylphenyl)amide (7).

Yield (48%), m.p. 290°C (dioxane); IR (KBr) ν max⁡: 3261, 3110 (NH, NH2), 1685 (C=O), cm−1; 1H NMR (DMSO-d6): δ 6.61 (s, 1H, D2O-exchangeable NH2), 7.05 (d, 2H, J = 9 Hz), 7.34–7.44 (m, 5H, Ar-H), 7.50 (d, 2H, J = 9 Hz), 7.68 (s, 1H, triazole-H), 8.09 (s, 1H, pyrimidine-H), 8.48 (s, 1H, D2O-exchangeable NH); MS m/z (%): 397 (M++3, 20.0), 394 (M+, 0.2), 157 (16.0), 121 (52.0), 76 (84.0), 63 (100.0). Anal. Calcd for C18H14N6O3S (394.41): C, 54.82; H, 3.58; N, 21.31; S, 8.13. Found: C, 54.80; H, 3.53; N, 21.25; S, 8.01%.

2.11. 2-Benzoyl-3-aryl-2-yl-N-(4-sulfamoylphenyl)acrylamide (8a, b)

General Procedure. To a solution of (1) (0.318 g, 1 mmol) and the appropriate aromatic aldehydes (1 mmol) in dioxane (20 mL), few drops of piperidine were added and the reaction mixture was refluxed for 6 hrs. So the solid product formed was filtered off, washed with EtOH, dried, and finally recrystallized from the proper solvent to give 8a, b.

2.12. 2-Benzoyl-3-furan-2-yl-N-(4-sulfamoylphenyl)acrylamide (8a)

Yield (45%), m.p. 220°C (EtOH); IR (KBr) ν max⁡: 3349, 3255 (NH, NH2), 1687 (C=O) cm−1; 1H NMR (DMSO-d6): δ 7.43 (s, 2H, D2O-exchangeable NH2), 7.46–7.61 (m, 8H, Ar-H), 7.64 (d, 2H, J = 9 Hz), 7.94 (d, 2H, J = 9 Hz), 8.48 (s, 1H, olefinic-H), 9.14 (s, 1H, D2O-exchangeable NH); MS m/z (%): 396 (M+, 0.1), 225 (0.3), 197 (0.4), 171 (22.4), 157 (2.8), 105 (100.0). Anal. Calcd for C20H16N2O5S (396.42): C, 60.60; H, 4.07; N, 7.07; S, 8.09. Found: C, 60.53; H, 4.01; N, 7.11; S, 8.00%.

2.13. 2-Benzoyl-3-(1,3-diphenyl-1H-pyrazol-4-yl)-N-(4-sulfamoylphenyl)acrylamide (8b)

Yield (50%), m.p. 180°C (EtOH); IR (KBr) ν max⁡: 3341, 3261 (NH, NH2), 3060 (aromatic CH), 1675 (C=O) cm−1; 1H NMR (DMSO-d6): δ 7.25 (s, 2H, D2O-exchangeable NH2), 7.49–7.00 (m, 15H, Ar-H), 7.64 (s, 1H, pyrazole-H), 7.77 (d, 2H, J = 9 Hz), 7.81 (d, 2H, J = 9 Hz), 7.86 (s, 1H, olefinic-H), 10.85 (s, 1H, D2O-exchangeable NH); MS m/z (%): 548 (M+, 0.1), 217 (16.7), 199 (20.0), 172 (16.7), 105 (96.7), 92 (20.0), 77 (100.0). Anal. Calcd for C31H24N4O4S (548.63): C, 67.87; H, 4.41; N, 10.21; S, 5.84. Found: C, 67.82; H, 4.35; N, 10.16; S, 5.78%.

2.14. 5-Furan-2-yl-3-phenyl-2,3-dihydro-1-H-pyrazole-4-carboxylic Acid (4-sulfamoylphenyl)amide (9a)

To a solution of the compound 8a (0.4 g, 1 mmol) in dioxane (20 mL), hydrazine hydrate (80%, 0.2 mL, 1 mmol) was added and the reaction mixture was refluxed for 6 hrs; then it was left to cool. So the solid product formed was filtered off, washed with EtOH, and dried. Recrystallization from dioxane afforded 9a.

Yield (40%), m.p. 244°C (EtOH); IR (KBr) ν max⁡: 3281, 3111 (NH, NH2), 1666 (C=O) cm−1; 1H NMR (DMSO-d6): δ 6.33–6.37 (m, 2H), 7.21 (s, 2H, D2O-exchangeable NH2), 7.44 (d, 2H, J = 9 Hz), 7.50 (d, 2H, J = 9 Hz), 7.56–7.75 (m, 6H, Ar-H), 9.99 (s, 1H, D2O-exchangeable NH), 10.42 (s, 1H, D2O-exchangeable NH); MS m/z (%): 408 (M+, 3.5), 171 (20.4), 142 (3.5), 77 (100). Anal. Calcd for C20H16N4O4S (408.44): C, 58.81; H, 3.95; N, 13.72; S, 7.85. Found: C, 58.79; H, 3.93; N, 13.65; S, 7.80%.

2.15. 2-Benzoyl-3-ethoxy-N-(4-sulfamoylphenyl)acrylamide (10)

To a solution of the compound 1 (3.18 g, 10 mmol) in acetic anhydride (20 mL), triethyl orthoformate (2 mL, 10 mmol) was added and the reaction mixture was refluxed for 8 hrs; then it was left to cool. So the solid product formed was filtered off, washed with EtOH, and dried. Recrystallization from dioxane afforded 2-benzoyl-3-ethoxy-N-(4-sulfamoylphenyl)acrylamide (10).

Yield (60%), m.p. 280°C (DMF); IR (KBr) ν max⁡: 3359, 3239 and 3107 (NH, NH2), 1655 (C=O) cm−1; 1H NMR (DMSO-d6): δ 1.26 (t, 3H, J = 7.2 Hz, CH3), 4.32 (q, 2H, J = 7.2, CH2), 7.16 (s, 2H, D2O-exchangeable NH2), 7.40 (d, 2H, J = 9 Hz), 7.69 (d, 2H, J = 9 Hz), 7.87–8.00 (m, 5H, Ar-H), 8.63 (s, 1H, CH), 11.25 (s, 1H, D2O-exchangeable NH); MS m/z (%): 374 (M+, 0.5), 370 (0.6), 301 (72.7), 198 (18.0), 172 (33.6), 156 (59.6), 105 (70.8), 77 (85.0), 65 (100.0). Anal. Calcd for C18H18N2O5S (374.42): C, 57.74; H, 4.85; N, 7.48; S, 8.56. Found: C, 57.70; H, 4.76; N, 7.41; S, 8.50%.

2.16. 4-(6-Phenyl-2-thioxo-2,3-dihydropyrimidin-4-ylamino)benzenesulfonamide (11)

To a mixture of 1 (0.318 g, 1 mmol) and thiourea (0.076 g, 1 mmol) in dimethylformamide (20 mL), triethylamine (0.5 mL) was added and the reaction mixture was refluxed for 6 hrs; then it was left to cool. The precipitated product was filtered off and purified by recrystallization from the suitable solvent to afford the corresponding 11.

Yield (45%), m.p. > 300°C (dioxane); IR (KBr) ν max⁡: 3500–3368 (NH, NH2), 3057 (aromatic CH), 1675 (C=O) cm−1; 1H NMR (DMSO-d6): δ 7.27 (s, 2H, D2O-exchangeable NH2), 7.54 (d, 2H, J = 9 Hz), 7.66 (d, 2H, J = 9 Hz), 7.68–7.97 (m, 6H, Ar-H), 11.85 (s, 1H, D2O-exchangeable NH), 12.23 (s, 1H, D2O-exchangeable NH). Anal. Calcd for C16H14N4O2S2 (358.44): C, 53.61; H, 3.94; N, 15.63; S, 17.89. Found: C, 53. 60; H, 3.90; N, 15.59; S, 17.84.%.

2.17. 2-Benzoyl-3-mercapto-3-phenylamino-N-(4-sulfamoylphenyl)acrylamide (13)

To a stirred solution of potassium hydroxide (0.11 g, 1 mmol) in dimethylformamide (20 mL) the 1 (0.318 g, 1 mmol) was added. After stirring for 30 min, phenylisothiocyanate (0.27 g, 0.24 mL, 1 mmol) was added to the resulting mixture and stirring was continued for 6 h; then it was poured over crushed ice containing hydrochloric acid. The solid product formed was filtered off, washed with water, dried, and finally recrystallized from dioxane to afford 13.

Yield (40%), m.p. 230°C (dioxane); IR (KBr) ν max⁡: 3350, 3256 (NH, NH2), 1689 (C=O), 1661 (C=O), cm−1; 1H NMR (DMSO-d6): δ 7.19 (s, 2H, D2O-exchangeable NH2), 7.39 (d, 2H, J = 9 Hz), 7.69 (d, 2H, J = 9 Hz), 7.71–7.90 (m, 10H, Ar-H), 10.39 (s, 1H, D2O-exchangeable NH), 11.13 (s, 1H, D2O-exchang-eable NH), 12.76 (s, 1H, SH); MS m/z (%): 455 (M++2, 26.3), 453 (M+, 1.5), 121 (26.3), 105 (100.0), 91 (47.4), 89 (36.8), 77 (89.5). Anal. Calcd for C22H19N3O4S2 (453.54): C, 58.26; H, 4.22; N, 9.26; S, 14.14. Found: C, 58.22; H, 4.20; N, 9.20; S, 14.11%.

2.18. N-[4-(Aminosulfonyl)phenyl]-2-anilino-4-phenyl-thiophene-5-benzoyl-3-carboxamide (14)

To a mixture of acrylamide 13 (1 mmol) and 2-bromo-1-phenylethanone (0.2 g, 1 mmol) in dimethylformamide (20 mL), triethylamine (0.5 mL) was added and the reaction mixture was refluxed for 6 hrs; then it was left to cool. The precipitated product was filtered off and purified by recrystallization from dioxane to afford the corresponding N-[4-(aminosulfonyl)phenyl]-2-anilino-4-phenyl-thiophene-5-benzoyl-3-carboxamide (14).

Yield (40%), m.p. 280°C (dioxane); IR (KBr) ν max⁡: 3425, 3276, 3111 (NH, NH2), 3059 (aromatic CH), 1698 (C=O), 1658 (C=O), cm−1; 1H NMR (DMSO-d6): δ 7.19 (s, 2H, D2O-exchangeable NH2), 7.27–7.73 (m, 15H, Ar-H), 7.76 (d, 2H, J = 9 Hz), 8.22 (d, 2H, J = 9 Hz), 9.55 (s, 1H, D2O-exchangeable NH), 9.98 (s, 1H, D2O-exchangeable NH); MS m/z (%): 555 (M++2, 16.0), 553 (M+, 1.5), 450 (20.0), 395 (20.0), 198 (24), 171 (36.0), 156 (24.0), 105 (92.0), 91 (16.0), 76 (20.0). Anal. Calcd for C30H23N3O4S2 (553.66): C, 65.08; H, 4.19; N, 7.59; S, 11.58. Found: C, 65.02; H, 4.15; N, 7.55; S, 11.54%.

2.19. Synthesis of 15, 16, 17, 18, and 20

To a stirred solution of potassium hydroxide (0.11 g, 1 mmol) in DMF (20 mL), compound 1 (0.318 g, 1 mmol) was added. After stirring for 30 min, phenyl isothiocyanate (0.27 g, 1 mmol) was added to the resulting mixture. Stirring was continued for 6 hrs, and then chloroacetone, ethyl chloroacetate, 3-(2-bromoacetyl)-2H-chromen-2-one, methyl iodide, or 2-oxo-N-phenylpropane hydrazonoyl chloride (1 mmol) was added portionwise over a period of 30 min. After the addition was complete, the reaction mixture was stirred for additional 12 h, during which the reactant dissolved and a yellow product precipitated. The solid product was filtered off, washed with EtOH, and dried; recrystallization from proper solvent afforded 15, 16, 17, 18, and 20.

2.20. N-[4-(Aminosulfonyl)phenyl]-2-anilino-4-phenyl-thiophene-5-acetyl-3-carboxamide (15)

Yield (65%), m.p. 268°C (dioxane); IR (KBr) ν max⁡: 3371, 3289 and 3220 (NH, NH2), 3059 (aromatic CH), 1636 (C=O), cm−1; 1H NMR (DMSO-d6): δ 1.72 (s, 3H, CH3), 7.11 (s, 2H, D2O-exchangeable NH2), 7.13 (d, 2H, J = 9 Hz), 7.38–7.46 (m, 10H, Ar-H), 7.63 (d, 2H, J = 9 Hz), 9.46 (s, 1H, D2O-exchangeable NH), 9.88 (s, 1H, D2O-exchangeable NH); 13C NMR (DMSO-d6): δ 28.15, 118.68, 119.93, 123.88, 126.36, 127.85, 128.42, 128.71, 129.20, 129.45, 134.89, 134.97, 138.46, 140.91, 141.32, 145.33, 157.02, 162.59, 189.30; MS m/z (%): 492 (M++1, 13.2), 491 (M+, 15.1), 320 (28.3), 292 (11.3), 187 (20.8), 105 (100.0), 77 (94.3). Anal. Calcd for C25H21N3O4S2 (491.59): C, 61.08; H, 4.31; N, 8.55; S, 13.04. Found: C, 61.00; H, 4.24; N, 8.5; S, 13.11%.

2.21. 3-Phenyl-5-phenylamino-4-(4-sulfamoylphenyl-carbamoyl)thiophene-2-carboxylic Acid Ethyl Ester (16)

Yield (55%), m.p. 280°C (dioxane); IR (KBr) ν max⁡: 3367, 3310 and 3235 (NH, NH2), 3060 (aromatic CH), 1713 (C=O), 1635 (C=O) cm−1; 1H NMR (DMSO-d6): δ 1.01 (s, 3H, J = 7.2 Hz, CH3), 4.04 (q, 2H, J = 7.2 Hz, CH2), 7.08–7.13 (m, 5H, Ar-H), 7.21 (d, 2H, J = 9 Hz), 7.39–7.44 (m, 7H, Ar-H and NH2), 7.63 (d, 2H, J = 9 Hz), 9.54 (s, 1H, D2O-exchangeable NH), 9.73 (s, 1H, D2O-exchangeable NH); MS m/z (%): 521 (M+, 26.3), 322 (15.8), 218 (100.0), 199 (15.8), 77 (86.0). Anal. Calcd for C26H23N3O5S2 (521.62): C, 59.87; H, 4.44; N, 8.06; S, 12.29. Found: C, 59.77; H, 4.41; N, 8.02; S, 12.21%.

2.22. N-[4-(Aminosulfonyl)phenyl]-2-anilino-4-phenyl-5-[(2-oxo-2H-chromen-3-yl)carbonyl]-thiophene-3-carboxamide (17)

Yield (55%), m.p. 200°C (EtOH); IR (KBr) ν max⁡: 3375, 3261 (NH, NH2), 1713 (C=O), cm−1; 1H NMR (DMSO-d6): δ 6.71–7.27 (m, 7H, Ar-H and NH2), 7.29 (d, 2H, J = 9 Hz), 7.42–7.59 (m, 10H, Ar-H), 7.63 (d, 2H, J = 9 Hz), 9.88 (s, 1H, D2O-exchangeable NH), 10.02 (s, 1H, D2O-exchangeable NH); MS m/z (%): 621 (M+, 6.8), 423 (100.0), 250 (15.1), 221 (8.2), 199 (8.2), 145 (24.7), 105 (65.8), 77 (87.7). Anal. Calcd for C33H23N3O6S2 (621.70): C, 63.76; H, 3.73; N, 6.76; S, 10.32. Found: C, 63.70; H, 3.61; N, 6.67; S, 10.25%.

2.23. 2-Benzoyl-3-methylsulfanyl-3-phenylamino-N-(4-sulfamoylphenyl)acrylamide (18)

Yield (30%), m.p. 260°C (dioxane); IR (KBr) ν max⁡: 3343, 3242 (NH, NH2), 1696 (C=O) cm−1; 1H NMR (DMSO-d6): δ 3.56 (s, 3H, SCH3), 7.24 (d, 2H, J = 9 Hz), 7.34–7.71 (m, 12H, Ar-H and NH2), 7.76 (d, 2H, J = 9 Hz), 10.50 (s, 2H, D2O-exchangeable 2NH); MS m/z (%): 467 (M+, 22.9), 296 (45.7), 197 (25.7), 139 (22.9), 105 (14.3), 92 (54.3), 63 (100). Anal. Calcd for C23H21N3O4S2 (467.56): C, 59.08; H, 4.53; N, 8.99; S, 13.72. Found: C, 59.12; H, 4.50; N, 8.96; S, 13.66%.

2.24. 2-(5-Acetyl-3-phenyl-3H-[1,3,4]thiadiazol-2-ylidene)-3-oxo-3-phenyl-N-(4-sulfamoylphenyl)propionamide (20)

Yield (35%), m.p. 220°C (dioxane); IR (KBr) ν max⁡: 3340, 3244 (NH, NH2), 3061 (aromatic CH), 1614 (C=O) cm−1; 1H NMR (DMSO-d6): δ 2.49 (s, 3H, CH3), 7.15 (s, 2H, D2O-exchangeable NH2), 7.30 (d, 2H, J = 9 Hz), 7.62 (d, 2H, J = 9 Hz), 7.65–8.39 (m, 10H, Ar-H), 11.95 (s, 1H, D2O-exchangeable NH); MS m/z (%): 522 (M++2, 14.6), 520 (M+, 41.6), 320 (27.0), 306 (13.9), 247 (10.2), 214 (7.3), 189 (8.8), 114 (7.3), 105 (20.4), 77 (100.0). Anal. Calcd for C25H20N4O5S2 (520.59): C, 57.68; H, 3.87; N, 10.76; S, 12.32. Found: C, 57.63; H, 3.82; N, 10.71; S, 12.29%.

2.25. Agar Diffusion Well Method to Determine the Antimicrobial Activity

The microorganism inoculums were uniformly spread using sterile cotton swab on a sterile Petri dish malt extract agar (for fungi) and nutrient agar (for bacteria). One hundred μL of each sample was added to each well (10 mm diameter holes cut in the agar gel, 20 mm apart from one another). The systems were incubated for 24–48 hours at 37°C (for bacteria) and at 28°C (for fungi). After incubation, the microorganism's growth was observed. Inhibition of the bacterial and fungal growth was measured in mm. Tests were performed in triplicate [31].

3. Results and Discussion

Heterocyclic azo compounds are well known for their use as antineoplastics [32], antidiabetics [33], antiseptics [34], and antibacterial activity [35] and are known to be involved in a number of biological reactions such as inhibition of DNA, RNA, protein synthesis, carcinogenesis, and nitrogen fixation [34-36]. Thus, propionamide 1 was coupled smoothly with diazonium salts, derived from the appropriate aromatic amines [4-methoxyaniline, 4-methylaniline, aniline, 4-chloroaniline, and 4-nitroaniline) in pyridine, to afford the respective hydrazones 3a–e (Scheme 1). The structures of the products were established on the basis of their elemental analyses and spectral data (IR, 1H NMR, and MS) [see Experimental Part]. In the 1H NMR spectra of compounds 3a–e, absence of signal assignable to azomethine group (CH–N=N–) [37] at δ 3.00–4.00 ppm ruled out azo form and supported the hydrazone structure of the products.

Scheme 1

Synthesis of hydrazones derivatives.

Further elucidation of the structure of 3b came from the reaction with malononitrile and triethyl orthformate to furnish the final isolable products corresponding to the 5-cyano-6-imino-4-phenyl-1-p-tolyl-1,6-dihydropyridazine-3-carboxylic acid (4-sulfamoylphenyl)amide (4) and 4-(6-benzoyl-3-ethoxy-5-oxo-2-p-tolyl-2,3-dihydro-1,2,4-triazin-4-(5H)-yl)benzenesulfonamide (5), respectively. The structures of compounds 4 and 5 were confirmed based on elemental analysis and spectral data studied (Scheme 2 and Experimental Part). Treatment of compound 1 with N,N-dimethylformamide-dimethylacetal (DMF-DMA) in refluxing dry dioxane afforded 2-benzoyl-3-dimethylamino-N-(4-sulfamoylphenyl)acrylamide (6). The 1H NMR spectrum of compound 6 showed signals at δ 3.42, 8.10, and 9.98 due to N,N-dimethylamino, C=CH–N, and amide-NH protons, respectively. When compound 6 was treated with 3-amino-1,2,4-triazole in acetic acid under reflux this led to formation of 1,2,4-triazolo [1,5-a] pyrimidine derivative 7 (Scheme 3). The IR spectrum of the isolated product showed absorption bands at 3261 and 3110 cm−1 characteristic for NH and NH2 function. Its 1H NMR spectrum showed signals at δ 7.68, 8.09, and 8.48 corresponding to triazole-H, pyrimidine-H, and D2O-exchangeable signal corresponding to NH protons, respectively. The pathway of formation of product 7 involves Michael addition of the exocyclic amino group of the heteroamines to the enaminone double bond of 6, followed by in situ tandem elimination of dimethylamine and dehydrative cyclization.

Scheme 2

Synthesis of 1,6-dihydropyridazine and 2,3-dihydro-1,2,4-triazine derivatives.

Scheme 3

Also, 1 reacts with aromatic aldehydes to afford the corresponding 2-benzoyl-3-aryl-2-yl-N-(4-sulfamoylphenyl)acrylamide derivatives 8a,b (Scheme 3). The IR spectrum of compound 8a, taken as a typical example, revealed absorption bands at 3349, 3255, and 1687 cm−1 corresponding to NH, NH2, and CO functions, respectively. Its 1H NMR spectrum showed signals at δ 8.48 and 9.14 corresponding to CH and NH protons in addition to aromatic protons at δ 7.46–7.94. Its mass spectrum showed a molecular ion peak at m/z 396. When the acrylamide derivative 8a was treated with hydrazine hydrate it afforded the corresponding pyrazole derivative 9a (Scheme 3). Spectroscopic data as well as elemental analyses of the obtained products were in complete agreement with the assigned structures 9a.

On the other hand, the reactivity of propionamide 1 towards triethylorthoformate and thiourea was investigated. Thus, condensation of 1 with triethylorthoformate in refluxing acetic anhydride afforded the ethoxy methylene derivative 10. Establishing of structure 10 was based on the elemental analysis and spectral data. Treatment of 1 with thiourea afforded the pyrimidine derivative 11. Establishing of compound 11 is based on its elemental analysis and spectral data (IR and 1H NMR) (Scheme 3).

Next, the nucleophilic addition of 1 to phenyl isothiocyanate in dimethylformamide, in the presence of potassium hydroxide, afforded the corresponding potassium salt 12. When the intermediate potassium salt was treated with dilute HCl, it gave the corresponding 2-benzoyl-3-mercapto-3-phenylamino-N-(4-sulfamoylphenyl)acrylamide (13) (Scheme 4).

Scheme 4

The IR spectrum of compound 13 revealed the absorption bands at 3350–3256 and 1689–1661 cm−1 corresponding to NH, NH2, and CO groups, respectively. Its 1H NMR spectrum showed two D2O-exchangeable signals at 10.39, 11.13, and 12.76 corresponding to 2NH and SH proton, respectively. Moreover, the mass spectrum of the product 13 exhibited a molecular ion peak at m/z 453. Treatment of compound 13 with 2-bromo-1-phenylethanone in dimethylformamide, in the presence of a catalytic amount of triethylamine, afforded the carboxamide 14 (Scheme 4). The structure of compound 14 was elucidated from its spectroscopic and elemental analytical data. Thus, it showed absorption bands at 3425–3111 and 1698–1658 cm−1 due to NH, NH2, and CO functions, whereas its 1H NMR spectra revealed two D2O-exchangeable signals at 9.55 and 9.98 corresponding to 2NH protons. Heterocyclisation of the intermediate with chloroacetone or ethyl 2-chloroacetate and 3-(2-bromoacetyl)-2H-chromen-2-one furnished in each case one isolable product (as tested by TLC). The reaction products were identified as N-[4-(aminosulfonyl)phenyl]-2-anilino-4-phenylthiophene-5-acetyl-3-carboxami-de (15), 3-phenyl-5-phenylamino-4-(4-sulfamoylphenyl-carbamoyl)thiophene-2-carboxylic acid ethyl ester (16), and N-[4-(aminosulfonyl)phenyl]-2-anilino-4-phenyl-5-[(2-oxo-2H-chromen-3-yl)carbonyl]thiophene-3-carboxamide (17). The reaction proceeds via nucleophilic displacement of bromide to give S-alkylated intermediate followed by loss of water of the latter intermediate to give thiophene derivatives 15 or 16 or 17 as the final products. The structures of the products 15–17 were determined from spectroscopic and elemental analytical data. Thus, compound 15, taken as a typical example, showed absorption bands at 3371, 3289, 3220, and 1636 cm−1 corresponding to NH, NH2, and C=O groups, respectively. Its 1H NMR spectrum revealed the absence of CH2 protons of chloroacetone and showed signals at δ 9.46 and 9.88 due to 2NH protons, in addition to an aromatic multiplet in the region δ 7.13–7.63. The 13C NMR of compound 15 revealed signals at 28.15, 162.59, and 189.30 for the carbons of the CH3 of (COCH3), CO of (CONH), and CO of (COCH3) groups.

Furthermore, the nonisolated potassium salt was methylated by treatment with methyl iodide to afford the novel ketene N, S-acetal 18. The structure of the synthesized product was established on the basis of their elemental analysis and spectral data [see the Experimental Part].

Heterocyclisation of the intermediate 12 with 2-oxo-N-phenylpropane hydrazonoyl chloride [38] furnished one isolable product (as tested by TLC). The reaction product was identified as 2-(5-acetyl-3-phenyl-3H-[1,3,4]-thiadiazol-2-ylidene)-3-oxo-3-phenyl-N-(4-sulfamoylphenyl)propionamide (20) (Scheme 4). The structure of the product 20 was determined from spectroscopic and elemental analytical data. Thus, the IR spectrum of compound 20 revealed absorption bands at 3340, 3244, and 1614 cm−1 corresponding to NH, NH2, and CO groups, respectively. Its 1H NMR spectrum revealed signals at δ 2.49 and 11.95 due to CH3 and NH protons, in addition to an aromatic multiplet in the region δ 7.30–8.39. The aforementioned results indicate that the reaction proceeds via S-alkylation [39], to give S-alkylated intermediate 19 which cyclized in situ under the employed reaction conditions and elimination of aniline molecule gave the desired product 20 (Scheme 4).

Screening for Antimicrobial Activity. The newly synthesized compounds 3a, 3c, 6, 7, 8b, 10, 15, 16, and 17 were evaluated for their in vitro antibacterial activity against Staphylococcus aureus (RCMB-000106) (SA) and Bacillus subtilis (RCMB-000108) (BS) as examples of Gram-positive bacteria and Pseudomonas aeruginosa (RCMB-000102) (PA) and Escherichia coli (RCMB-000103) (EC) as examples of Gram-negative bacteria. They were also evaluated for their in vitro antifungal activity against Aspergillus fumigatus (RCMB-002003) (AF), Saccharomyces cerevisiae (RCMB-006002) (SC), and Candida albicans (RCMB-005002) (CA) fungal strains. Inhibition zone diameter (IZD) in mm was used as criterion for the antimicrobial activity using the agar diffusion well method. The fungicide clotrimazole and the bactericide streptomycin were used as references to evaluate the potency of the tested compounds under the same conditions. The results are depicted in Table 1. From the data given by Table 1 we concluded that most of the tested compounds displayed variable degrees of antibacterial activity against Gram-positive bacteria, Gram-negative bacteria strains, and also against fungal strains in comparison to the standard in each case which revealed that these compounds are biologically active. Compound 7 exhibited high degree of antibacterial activity against Gram-positive bacteria (SA). Compounds 3c and 7 have moderate degree of antibacterial activity against Gram-negative bacteria (EC) and (PA). All the compounds exhibited moderate antifungal activity against (AF) and high activity against (SC, CA). The structure antimicrobial activity relationship of the synthesized compounds revealed that the maximum activity was attained with compound 15, having acetyl thiophene moiety.

Table 1

Antimicrobial and Antifungal Activities of the Synthesized Compounds.

Sample no.	Inhibition zone diameter (mm)
	Gram (−)		Gram (+)		Fungi
	(PA)	(EC)	(SA)	(BS)	(AF)	(SC)	(CA)
3a	10.7 ± 0.3	10.1 ± 0.4	12.2 ± 0.3	11.1 ± 0.4	11.9 ± 0.4	12.5 ± 0.4	13.4 ± 0.4
3c	12.9 ± 0.4	11.7 ± 0.4	12.1 ± 0.4	12.3 ± 0.4	18.7 ± 0.4	20.8 ± 0.6	14.7 ± 0.5
6	10.6 ± 0.3	10.8 ± 0.4	12.2 ± 0.4	11.3 ± 0.4	17.1 ± 0.5	17.9 ± 0.6	14.8 ± 0.4
7	13.4 ± 0.4	13.1 ± 0.4	19.7 ± 0.4	20.1 ± 0.5	17.6 ± 0.4	18.8 ± 0.5	13.9 ± 0.5
8b	11.1 ± 0.3	12.7 ± 0.4	11.8 ± 0.3	11.5 ± 0.4	15.3 ± 0.5	19.1 ± 0.4	15.2 ± 0.5
10	9.7 ± 0.2	8.9 ± 0.4	11.2 ± 0.4	10.8 ± 0.4	12.1 ± 0.5	11.9 ± 0.4	11.7 ± 0.5
15	24.3 ± 0.1	25.6 ± 0.1	25.1 ± 0.5	30.1 ± 0.6	26.1 ± 0.5	23.1 ± 0.4	18.3 ± 0.6
16	11.1 ± 0.4	10.3 ± 0.3	9.8 ± 0.3	10.9 ± 0.4	11.4 ± 0.3	12.2 ± 0.4	11.3 ± 0.5
17	9.2 ± 0.3	7.8 ± 0.4	8.9 ± 0.3	9.7 ± 0.3	10.5 ± 0.4	10.3 ± 0.4	9.5 ± 0.4
Clotrimazole	—	—	—	—	26.1 ± 0.5	23.1 ± 0.4	18.3 ± 0.6
Streptomycin	—	—	25.1 ± 0.5	30.1 ± 0.6	—	—	—
Streptomycin	24.3 ± 0.4	25.6 ± 0.5	—	—	—	—	—

Data are expressed in the form of mean ± SD. Mean zone of inhibition in mm ± Standard deviation beyond well diameter (6 mm) produced on a range of environmental and clinically pathogenic microorganism using (5 mg/mL) concentration of tested sample (100 μL was tested).

4. Conclusions

Several new hydrazones, pyridazines, triazines, acrylamides, pyrazoles, triazolo[1,5-a]pyrimidines, thiadiazoles, dihydropyrimidines, and thiophenes containing sulfamoyl moiety were prepared using simple methods via a versatile; readily accessible 3-oxo-3-phenyl-N-(4-sulfamoylphenyl)propionamide (1) is demonstrated. The structures of the newly synthesized compounds were proven by spectral methods and they were tested for their antimicrobial activities. Most of these compounds showed promising activities against both Gram-positive, Gram-negative bacteria and fungi.