Synthesis of 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid derivatives and their antimicrobial activities
-
Emine Şahan
,
İsmail Yıldırım
Abstract
The reaction of 1H-pyrazole-3-carboxylic acid chloride (1) with various hydrazine derivatives 2a–c yielded the corresponding N,N-disubstituted 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carbohydrazides 3a–c. These products underwent Friedel-Crafts acylations with arenes to afford compounds 4a–c. Treatment of 1 with aromatic diamines produced 1H-pyrazole-3-carboxamides 5a–c, which were allowed to react with phenylhydrazine to give hydrazone derivatives 6a–c. The structures of all new compounds were established by IR, 1H and 13C NMR data and elemental analyses. The new compounds were evaluated for antimicrobial activities against Gram (-), Gram (+) bacteria and two yeasts using the disc diffusion method. N,N-Dimethylhydrazide derivative 3a is the most active compound of the series.
Introduction
Pyrazole derivatives are an important class of heterocyclic compounds [1–8] that have considerable pharmacological activities including antibacterial, antifungal and hypoglycemic activities [9–14]. A number of hydrazide/hydrazone derivatives have also been claimed to possess interesting bioactivity, such as anticonvulsant, anti-inflammatory, antimalarial, analgesic, antiplatelets, antituberculosis and anticancer properties. Aroylhydrazide/hydrazones that are derivatives of heterocyclic compounds such as pyridine have attracted particular attention [15–19] in drug development [20]. Functionalization of 1H-pyrazole-3-carboxylic acid chloride (1) by the reaction with various diamines has been reported by Yıldırım and co-workers [3–5], but no reaction of 1H-pyrazole-3-carboxamides with nucleophiles has been described. Herein, we report the synthesis and characterization of pyrazole derivatives 3a–c, 4a–c and 6a–c.
Results and discussion
Chemistry
The 1H-pyrazole-3-carboxylic acid chloride 1 was prepared using the literature procedure [1, 2]. The reaction of compound 1 with substituted hydrazines 2a–c led to the formation of the corresponding products 3a–c in good yields (63–87%) (Scheme 1). The progress of the reaction was monitored by thin layer chromatography (TLC) until complete consumption of the starting materials was observed. The structures of products 3 were confirmed by elemental analysis, IR and 1H and 13C NMR spectroscopic techniques.
Friedel-Crafts acylation of selected arenes with the 1H-pyrazole-3-carboxylic acid chloride 1 in the presence of anhydrous aluminum chloride to afford 4a–c is also presented in Scheme 1. Recently, an analogous reaction of 1 with benzene was reported by ţener and co-workers [9]. The formation of products 4a–c is strongly supported by the results of elemental analyses and spectroscopic measurements. The reactions of compound 1 with some aromatic diamines to give the corresponding dicarboxamide derivatives 5a–c have recently been reported (Scheme 2) [4, 5]. Compounds 5a–c were allowed to react with phenylhydrazine to give new hydrazone derivatives 6a–c.
In vitro antimicrobial activity
All new compounds were evaluated against eight Gram (-), five Gram (+) and two yeasts. The results with the active compounds 3a, 3c, 4b and 6b are shown in Table 1. The antibacterial antibiotics ampicillin (AMP) and chloramphenicol (C) were used as controls. Compounds 3b, 4a, 4c, 6a and 6c were practically inactive against the tested microorganisms. All compounds had no inhibitory effects on yeasts tested in the present study. Compound 5c was slightly effective against Mycobacterium smegmatis among the tested microorganisms.
Screening for antimicrobial activity of selected compounds 3a, 3c, 4b and 6ba.
| Microorganisms | 3a | 3c | 4b | 6b | AMPc | Cc |
|---|---|---|---|---|---|---|
| Gram (-) | ||||||
| Aeromonas hydrophila ATCC 7965 | 8.75±0.4b | – | – | – | 27.0±0.0 | 18.0±0.0 |
| Escherichia coli ATCC 25922 | 8.5±0.7 | – | – | – | 6.5±0.0 | 17.0±0.0 |
| Klebsiella pneumoniae FMC 5 | 10.0±0.0 | – | – | – | 14.0±0.0 | 13.0±0.0 |
| Morganella morganii | 9.5±0.7 | – | – | – | – | 11.0±0.0 |
| Salmonella typhimurium NRRLE 4463 | 8.25±0.4 | – | – | – | 24.0±0.0 | 22.0±0.0 |
| Proteus mirabilis BC 3624 | – | – | – | – | 26.0±0.0 | 19.0±0.0 |
| Pseudomonas aeruginosa ATCC 27853 | 6.5±0.0 | – | – | – | 25.0±0.0 | 15.0±0.0 |
| Yersinia enterocolitica ATCC 1501 | – | – | – | – | 8.0±0.0 | 17.0±0.0 |
| Gram (+) | ||||||
| Bacillus brevis FMC 3 | 9.0±0.0 | – | 7.0±0.0 | – | 8.0±0.0 | 20.0±0.0 |
| B. cereus RSKK 863 | 7.25±0.4 | – | – | – | 31.0±0.0 | 21.0±0.0 |
| B. subtilis ATCC 6633 | 8.5±0.0 | – | – | – | 24.0±0.0 | 25.0±0.0 |
| Mycobacterium smegmatis RUT | 8.5±0.7 | 6.75±0.4 | – | 7.0±0.0 | 25.0±0.0 | 17.0±0.0 |
| Staphylococcus aureus ATCC 29213 | 8.5±0.0 | – | – | – | 16.0±0.0 | 15.0±0.0 |
| Yeast | ||||||
| Candida albicans ATCC 1223 | – | – | – | – | – | – |
| Saccharomyces cerevisiae BC 5461 | – | – | – | – | – | – |
aThe inhibition zones (mm) are shown.
bInhibition zones include diameter of disc (6 mm).
cAmpicillin (AMP, 10 μg); chloramphenicol (C, 30 μg). –, not detected.
The strongest activity was displayed by compound 3a.
Experimental
Solvents were dried by heating under reflux with appropriate drying agents and distilled before use. Melting points were determined on an Electrothermal 9200 apparatus and are uncorrected. Microanalyses were performed on a Carlo Erba Elemental Analyzer, model 1108. The IR spectra were recorded on a Shimadzu Model 8400 FT IR spectrophometer. The 1H NMR spectra (400 MHz) and 13C NMR spectra (100 MHz) were recorded on a Bruker-400 Ultra Shield instrument. All experiments were followed by TLC using a DC Alufolien Kieselgel 60 F254 Merck and Camag TLC lamp (254/366 nm).
Antimicrobial assay
Bacterial strains used in the present study were obtained from the Department of Biology, Faculty of Science, Erciyes University, Kayseri, Turkey. The bacterial strains were Aeromonas hydrophila ATCC 7965, Bacillus brevis FMC 3, Bacillus cereus RSKK 863, Bacillus subtilis ATCC 6633, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 27736, Morganella morganii, Mycobacterium smegmatis RUT, Proteus mirabilis BC 3624, Pseudomonas aeruginosa ATCC 27853, Salmonella typhimurium NRRLE 4463, Staphylococcus aureus ATCC 29213 and Yersinia enterocolitica ATCC 1501. The yeasts were Candida albicans ATCC 1223 and Saccharomyces cerevisiae BC 5461 (Table 1). Antimicrobial activity testing was carried out by disc diffusion methods [21] using 100 μL of suspension containing 106–107 colony forming units (cfu)/mL of bacteria and yeasts spread on nutrient agar (NA) and sabouraud dextrose agar (SDA). The sterile discs (6 mm) were impregnated with 10 μL of compounds in dimethyl sulfoxide (DMSO; 500 mg/disc) placed in the middle of inoculated agar plates. DMSO was added on the disc to provide negative control. Ampicillin (AMP, 10 μg) and chloramphenicol (C, 30 μg) were used as positive controls. Yeasts C. albicans and S. cerevisiae were incubated at 25°C for 24–48 h in the inverted position. Other microorganisms were incubated at 37°C for 18–24 h. At the end of the period, antimicrobial activity was evaluated by measuring the zone of inhibition (mm), and experiments were repeated twice.
General procedure for 3a–c
A solution of acid chloride 1 (0.20 g), N,N-disubstituted hydrazine 2a–c (0.04 mL) (molar ratio 1:1) and a catalytic amount of pyridine in xylene was heated under reflux for 2 h. Then the solvent was removed and the remaining oily residue was treated with dry diethyl ether and the mixture was stirred for 1 h. The resultant solid product 3 was crystallized from toluene or cyclohexane and dried over P2O5.
4-Benzoyl-3-[(N′,N′-dimethylhydrazino)carbonyl]-1,5-diphenyl-1H-pyrazole (3a)
White powder; mp 148–149°C; IR: υ 3209 (N-H), 2959 (aliph. C-H), 1670, 1650 cm-1 (C=O); 1H NMR: δ 3.00 (s, 6H, CH3) 7.12–7.90 (m, 15H, ArH), 9.30 (s, 1H, NH); 13C NMR: δ 46.6, 122.1, 125.4, 127.7, 128.3, 128.5, 128.6, 129.1, 129.4, 129.5, 129.8, 133.2, 137.8, 138.6, 143.4, 144.2, 158.7, 191.3. Anal. Calcd for C25H22N4O2: C, 73.15; H, 5.40; N, 13.65. Found: C, 72.80; H, 5.67; N, 13.96.
4-Benzoyl-1,5-diphenyl-3-[(N′,N′-diphenylhydrazino)carbonyl]-1H-pyrazole (3b)
White powder; mp 207–208°C; IR: υ 3284 (N-H), 1686, 1662 cm-1 (C=O); 1H NMR: δ 7.00–7.90 (m, 25H, ArH), 9.18 (s, 1H, NH); 13C NMR: δ 119.7, 120.2, 120.4, 122.4, 123.0, 125.4, 127.8, 128.2, 128.5, 128.6, 128.9, 129.1, 129.1, 129.3, 129.5, 129.9, 133.1, 138.0, 138.8, 144.1, 144.2, 145.9, 159.7, 191.2. Anal. Calcd for C35H26N4O2: C, 78.63; H, 5.90; N, 10.48. Found: C, 78.54; H, 5.43; N, 10.73.
4-Benzoyl-1,5-diphenyl-3-{N′-[(4-methylphenyl)hydrazino]carbonyl}-1H-pyrazole (3c)
White powder; mp 175–176°C; IR: υ 3269 (N-H), 2920 (aliph. C-H), 1678, 1662 cm-1 (C=O); 1H NMR: δ 3.02 (s, 3H, CH3) 6.70–7.85 (m, 20H, ArH), 8.75 (s, 1H, NH); 13C NMR: δ 40.8, 113.1, 113.4, 119.7, 122.3, 125.4, 127.9, 128.2, 128.5, 128.5, 128.6, 129.0, 129.1, 129.3, 129.5, 129.9, 133.1, 138.0, 138.8, 144.1, 144.3, 149.3, 159.5, 191.4. Anal. Calcd for C30H24N4O2: C, 76.25; H, 5.12; N, 11.86. Found: C, 76.05; H, 5.65; N, 11.30.
General procedure for 4a–c
A mixture of acid chloride 1 (0.40 g) anhydrous AlCl3 (0.70 g) and an aromatic compound (molar ratio 1:5:25) was heated at 100–140°C for 1–3 h in a calcium chloride guard tube fitted round bottom flask of 50 mL. Then, the mixture was poured onto HCl/ice-water for hydrolysis and extracted with diethyl ether. Then, petroleum ether was added and the resulting solid was collected and crystallized from ethanol.
4-Benzoyl-1,5-diphenyl-3-(4-methylbenzoyl)-1H-pyrazole (4a)
Compound 4a was prepared from toluene with heating for 1 h at 120°C; yield 61% (0.28 g); white powder; mp 192–193°C; IR: υ 1666, 1639 cm-1 (C=O); 1H NMR: δ 2.45 (s, 3H, CH3), 7.25–8.30 (m, 19H, Ar-H); 13C NMR: δ 21.7, 124.2, 125.4, 128.1, 128.3, 128.4, 128.5, 128.9, 129.0, 129.2, 129.9, 130.7, 132.9, 134.0, 138.1, 139.1, 143.3, 143.9, 150.2, 186.4, 191.5. Anal. Calcd for C30H22N2O2: C, 81.43; H, 5.01; N, 6.33. Found: C, 81.18; H, 5.00; N, 5.99.
4-Benzoyl-1,5-diphenyl-3-(4-chlorobenzoyl)-1H-pyrazole (4b)
Compound 4b was prepared from chlorobenzene with heating for 2 h at 100°C; yield 42% (0.20 g); white powder; mp 180–181°C; IR: υ 1666, 1639 cm-1 (C=O); 1H NMR: δ 7.20–8.35 (m, 19H, Ar-H); 13C NMR: δ 124.4, 125.4, 127.8, 128.4, 128.5, 129.1, 129.2, 129.3, 129.9, 132.1, 133.1, 134.8, 137.3, 139.0, 139.6, 143.4, 149.6, 185.3, 191.4. Anal. Calcd for C29H19N2O2Cl: C, 75.24; H, 4.14; N, 6.05. Found: C, 75.28; H, 4.17; N, 5.57.
4-Benzoyl-1,5-diphenyl-3-(4-bromobenzoyl)-1H-pyrazole (4c)
Compound 4c was prepared from bromobenzene with heating for 2 h at 140°C; yield 56% (0.28 g); white powder; mp 172–173°C; IR: υ 1660, 1649 cm-1 (C=O);1H NMR: δ 7.25–8.30 (m, 19H, Ar-H); 13C NMR: δ 124.4, 125.4, 125.4, 127.8, 127.9, 128.2, 128.4, 128.4, 128.4, 128.5, 128.6, 129.1, 129.1, 129.2, 129.3, 129.4, 129.8, 129.9, 130.6, 131.6, 132.2, 133.0, 133.1, 135.2, 136.5, 137.9, 138.1, 138.9, 143.5, 149.6, 185.5, 191.4. Anal. Calcd for C29H19N2O2Br: C, 68.65; H, 3.77; N, 5.52. Found: C, 68.27; H, 4.12; N, 5.37.
General procedure for 6a–c
A solution of compound 5a–c (0.30 g), phenylhydrazine (0.50 mL) (molar ratio 1:13) and a catalytic amount of acetic acid in n-butanol (10 mL) was heated under reflux for 15 h. The solvent was removed and the remaining oily residue was treated with dry diethyl ether and the mixture stirred for 1 h. The yellow solid product was crystallized from benzene or xylene.
N,N′-Bis{4-[α-(phenylhydrazono)benzyl]-1,5-diphenyl-1H-pyrazol-3-yl-carbonyl}-1,2-phenylendiamine (6a)
Yellow powder; mp 198–199°C. IR: υ 3225 (N-H), 1659 cm-1 (C=O); 1H NMR: δ 6.72–7.54 (m, 44H, ArH), 9.34 and 9.37 (2s, 2H, NH), 10.11 and 10.13 (2s, 2H, Ph-NH); 13C NMR: δ 113.1, 120.2, 124.8, 125.0, 125.3, 125.9, 126.0, 126.1, 127.6, 128.0, 128.1, 128.3, 128.8, 129.0, 129.1, 129.3, 129.4, 129.7, 129.9, 136.3, 138.4, 143.8, 144.8, 145.1, 159.3, 170.0. Anal. Calcd for C64H48N10O2: C, 77.71; H, 4.98; N, 14.16. Found: C, 77.32; H, 4.91; N, 13.99.
N,N′-Bis{4-[α-(phenylhydrazono)benzyl]-1,5-diphenyl-1H-pyrazol-3-yl-carbonyl}-4-chloro-1,2-phenylendiamine (6b)
Yellow powder; mp 239–240°C; IR: υ 3232, 3163 (N-H), 1662 cm-1 (C=O); 1H NMR: δ 6.73–7.73 (m, 43H, ArH), 9.33 and 9.38 (2s, 2H, NH), 10.15, 10.19, 10.21 and 10.24 (4s, 4H, Ph-NH); 13C NMR: δ 113.4, 125.5, 125.5, 125.5, 125.6, 128.9, 129.3, 129.3, 129.4, 144.5, 159.8, 178.1. Anal. Calcd for C64H47N10O2Cl: C, 75.10; H, 4.63; N, 13.68. Found: C, 74.87; H, 4.80; N, 13.15.
N,N′-Bis{4-[α-(phenylhydrazono)benzyl]-1,5-diphenyl-1H-pyrazol-3-yl-carbonyl}-4-nitro-1,2-phenylendiamine (6c)
Yellow powder; mp 257–258°C; IR: υ 3315 (N-H), 1678 cm-1 (C=O); 1H NMR: δ 6.74–8.32 (m, 43H, ArH), 9.38 and 9.40 (2s, 2H, NH), 10.40, 10.45, 10.54 and 10.56 (4s, 4H, Ph-NH); 13C NMR: δ 113.5, 125.5, 126.4, 128.5, 128.7, 129.0, 129.3, 129.5, 130.1, 159.8, 161.18, 170.9. Anal. Calcd for C64H47N11O4: C, 73.79; H, 4.38; N, 13.35. Found: C, 73.70; H, 4.66; N, 13.85.
The authors are grateful for the financial support by the Research Foundation of Erciyes University (Kayseri, Turkey), Project No. FBT-07-48.
References
[1] Akçamur, Y.; Şener, A.; İpekoğlu, A. M.; Kollenz, G. Functionalization and cyclization reactions of 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid. J. Heterocycl. Chem. 1997, 34, 221–224.Search in Google Scholar
[2] Şener, A.; Kasımoğulları, R.; Şener, M. K.; Bildirici, I.; Akçamur, Y. Studies on the reactions of cyclic oxalyl compounds with hydrazines or hydrazones: synthesis and reactions of 4-benzoyl-1-(3-nitrophenyl)-5-phenyl-1H-pyrazole-3-carboxylic acid. J. Heterocycl. Chem. 2002, 39, 869–871.Search in Google Scholar
[3] Yıldırım, İ.; Kandemirli, F.; Akçamur, Y. Experimental and quantum-chemical calculations on some 1H-pyrazole-3-carboxamide and -3-carboxylate derivatives formation. J. Mol. Struct. 2005, 738, 275–279.Search in Google Scholar
[4] Yıldırım, İ.; Kandemirli, F.; Demir, E. Experimental and theoretical studies on the functionalization reactions of 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid and -acid chloride with 2,3-diaminopyridine. Molecules2005, 10, 559–571.Search in Google Scholar
[5] Yıldırım, İ.; Kandemirli, F. Synthesis and theoretical calculations of the 1H-pyrazole-3-carboxamide and -3-carboxylate derivatives. Heterocycl. Commun. 2005, 11, 223–234.Search in Google Scholar
[6] Dinçer, M.; Özdemir, N.; Yıldırım, İ.; Demir, E.; Işık, S. Methyl 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylate. Acta Cryst. E2004, 60, 946–948.Search in Google Scholar
[7] Yıldırım, İ.; Kandemirli, F. Experimental and theoretical studies on the functionalization reactions of 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid and -acid chloride with various aminophenols. Struct. Chem. 2006, 17, 241–247.Search in Google Scholar
[8] Korkusuz, E.; Yıldırım, İ. Synthesis and reactions of 4-benzoyl-1,5-diaryl-1H-pyrazole-3-carbonyl chlorides with various semi- and thiosemicarbazides. J. Heterocycl. Chem. 2010, 47/2, 472–476.Search in Google Scholar
[9] Bildirici, İ.; Şener, A.; Tozlu, İ. Further derivatives of 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid and their antibacterial activities. Med. Chem. Res. 2007, 16, 418–426.Search in Google Scholar
[10] Yıldırım, İ.; Özdemir, N.; Akçamur, Y.; Dinçer, M.; Andaç, O. 4-Benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid methanol solvate. Acta Cryst. E2005, 61, 256–258.Search in Google Scholar
[11] Akbas, E.; Berber, I.; Sener, A.; Hasanov, B. Synthesis and antibacterial activity of 4-benzoyl-1-methyl-5-phenyl-1H-pyrazole-3-carboxylic acid and derivatives. Il Farmaco2005, 60, 23–26.Search in Google Scholar
[12] Badawey, E.; El-Ashmawey, I. M. Antiinflammatory, analgesic and antipyretic activity of some new 1-(pyrimidin-2-yl)-3-pyrazolin-5-ones and 2-(pyrimidin-2-yl)-1,2,4,5,6,7-hexahydro-3H-indazol-3-ones. Eur. J. Med. Chem. 1998, 33, 349–362.Search in Google Scholar
[13] Tewari, A. K.; Mishra, A. Synthesis and anti-inflammatory activities of N4,N5-disubstituted-3-methyl-1H-pyrazolo[3,4-c]pyridazines. Bioorg. Med. Chem. 2001, 9, 715–718.Search in Google Scholar
[14] Rostom, S. A. F.; Shalaby, M. A.; El-Demellawy, M. A. Polysubstituted pyrazoles, part 5.1. Synthesis of new 1-(4-chlorophenyl)-4-hydroxy-1H-pyrazole-3-carboxylic acid hydrazide analogs and some derived ring systems. A novel class of potential antitumor and anti-HCV agents. Eur. J. Med. Chem. 2003, 38, 959–974.Search in Google Scholar
[15] Küçükgüzel, S. G.; Mazi, A.; Sahin, F.; Öztürk, S.; Stables, J. Synthesis and biological activities of diflunisal hydrazide-hydrazones. Eur. J. Med. Chem. 2003, 38, 1005–1013.Search in Google Scholar
[16] Todeschini, A. R.; Miranda, A. L. P.; Silva, K. C. M.; Parrini, S. C.; Barreiro, E. J. Synthesis of new 2-pyridinylarylhydrazones and evaluation of their analgesic, anti-inflammatory and antiplatelet profile. Eur. J. Med. Chem. 1998, 33, 189–200.Search in Google Scholar
[17] Melnyk, P.; Leroux, V.; Sergheraert, C.; Grellier, P. Design, synthesis and in vitro antimalarial activity of an acylhydrazone library. Bioorg. Med. Chem. Lett. 2006, 16, 31–35.Search in Google Scholar
[18] Leite, L. F. C. C.; Ramos, M. N.; da Silva, J. B. P.; Miranda, A. L. P.; Fraga, C. A. M.; Barreiro, E. J. Synthesis and analgesic profile of novel N-containing heterocycle derivatives: arylidene 3-phenyl-1,2,4-oxadiazole-5-carbohydrazide. Il Farmaco1999, 54, 747–757.Search in Google Scholar
[19] Galic, N.; Peric, B.; Kojic-Prodic, B.; Cimerman, Z. Structural and spectroscopic characteristics of aroylhydrazones derived from nicotinic acid hydrazide. J. Mol. Struct. 2001, 559, 187–194.Search in Google Scholar
[20] Donohue, M. P.; Marchuk, D. A.; Rockman, H. A. Redefining heart failure: the utility of genomics. J. Am. Coll. Cardiol. 2006, 48, 1289–1298.Search in Google Scholar
[21] Isik, K.; Özdemir-Kocak, F. Antimicrobial activity screening of some sulfonamide derivatives on some Nocardia species and isolates. Microbiol. Res. 2009, 164, 49–58.Search in Google Scholar
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Articles in the same Issue
- Masthead
- Masthead
- Review
- Indoloquinolines as DNA binding ligands
- Preliminary Communication
- One-pot synthesis and crystal structure of an unusual amidine derived from heterocyclic ketene aminal derivative
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- A general and efficient entry to asymmetric tetrazines for click chemistry applications
- Synthesis, characterization and spectroscopic studies of two new 1-acetyl-3-alkylimidazolium ionic liquids
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