Condensed bridgehead nitrogen heterocyclic system: synthesis and pharmacological activities of 1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazole derivatives of ibuprofen and biphenyl-4-yloxy acetic acid

An expedient approach to synthesize fluorescent 3-substituted 4H-quinolizin-4-ones via (η4-vinylketene)-Fe(CO)3 complexes

From simple starting materials, an efficient methodology for the synthesis of 3-substituted 4H-quinolizin-4-ones using (η⁴-vinylketene)-Fe(CO)₃ complexes as key intermediates was developed. Fluorescent properties and quantum yields were determined.

In silico binding affinity to cyclooxygenase-II and green synthesis of benzylpyrazolyl coumarin derivatives

Here, we have reported enhanced molecular binding affinities of benzylpyrazolyl coumarin scaffolds with COX-II inhibitor and an ionic liquid catalyzed simple green synthetic route to access these scaffolds.

Synthesis and biological properties of novel triazole-thiol and thiadiazole derivatives of the 1,2,4-Triazole-3(5)-one class

2,2'-(4,4'(Butane-1,4-diyl/hexane-1,6-diyl)bis(3-methyl-5-oxo-4,5-dihydro-1,2,4-triazole-4,1-diyl)) diacetohydrazides 3a,b were obtained via the formation of diethyl 2,2'-(4,4'(butane-1,4-diyl/hexane-1,6-diyl)bis(3-methyl-5-oxo-4,5-dihydro-1,2,4-triazole-4,1-diyl))diacetates 2a,b, obtained starting from di-[3(methyl-2-yl-methyl)-4,5-dihydro-1H-[1,2,4]-triazole-5-one-4yl]-n-alkanes 1a,b in two steps. The synthesis of the compounds 7a,b–9a,b incorporating the 1,3,4-thiadiazole, and 10a,b–11a,b with a 1,2,4-triazole-thiol nucleus as the second heterocycle, was performed by the acidic or basic treatment of compounds 4a,b–6a,b which were obtained from the reaction of 3a,b with several isothiocyanates. Newly synthesized compounds were screened for antimicrobial activities and their antioxidant properties by the 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging method. Compounds 4a,b, 5a,b, and6a,b were found to possess good antioxidant properties. Almost all compounds have significant antimicrobial activities.

Synthetic methods, chemistry, and the anticonvulsant activity of thiadiazoles

The chemistry of heterocyclic compounds has been an interesting field of study for a long time. Heterocyclic nucleus 1,3,4-thiadiazole constitutes an important class of compounds for new drug development. The synthesis of novel thiadiazole derivatives and investigation of their chemical and biological behavior have gained more importance in recent decades. The search for antiepileptic compounds with more selective activity and lower toxicity continues to be an active area of intensive investigation in medicinal chemistry. During the recent years, there has been intense investigation of different classes of thiadiazole compounds, many of which possess extensive pharmacological activities, namely, antimicrobial activity, anticonvulsant, antifungal antidiabetic, anti-inflammatory, antioxidant, and antituberculosis activities, and so forth. The resistance towards available drugs is rapidly becoming a major worldwide problem. The need to design new compounds to deal with this resistance has become one of the most important areas of research today. Thiadiazole is a versatile moiety that exhibits a wide variety of biological activities. Thiadiazole moiety acts as "hydrogen binding domain" and "two-electron donor system." It also acts as a constrained pharmacophore. On the basis of the reported literature, we study here thiadiazole compounds and their synthetic methods chemistry and anticonvulsant activity.

Synthesis and biological activities of some novel aminomethyl derivatives of 4-substituted-5-(2-thienyl)-2,4-dihydro-3H-1,2,4-triazole-3-thiones

A novel series of compounds were synthesized by cyclic condensation reaction of substituted isothiocyanate (2a-c) with 2-thiophenecarboxylic acid hydrazide (1) in the presence of ethyl alcohol, to obtain intermediate thiosemicarbazides (3a-c), which were further treated with sodium hydroxide in the presence of ethanol to obtain triazole derivatives (4a-c). The latter were refluxed with substituted secondary amines and formaldehyde for 6-10 h to afford Mannich bases (5a-k). The synthesized compounds were characterized on the basis of their spectral (IR, (13)C and (1)H NMR) data and evaluated for biological activities. Some of the compounds were found to exhibit significant antimicrobial and antioxidant activity.

Synthesis of a New Class of Tris- and Bis(1,3,4-thiadiazol-2-amine) Methyl and Ethyl Tris- and Bis-2-(2-(2-benzoyl hydrazinyl)-4-oxothiazolidine) Acetate Derivatives

Hydrazine, carbothioamide derivatives2,3, and4were synthesized by the condensation of 1, 3, 5-tri carbonyl tri chloride, Terephthaloyl dichloride, and 1, 4-dicarbonyl chloride with thiosemicarbazide in presence of pyridine as a solvent. The reaction of compounds2,3, and4with DMAD or DEAD led to the formation of 4-oxothiozolidine derivatives(4b–c),(3a-c), and(2c-d). The treatment of compounds2,3, and4with 1, 4′-diboromoacetophenone resulted in the formation of thiazole derivatives(2g, 3f, 4f). The treatment of compounds2,3, and4with sulfuric led to the formation of 4H-1,2,4-triazole-3-thiol derivatives (2f,3d, and4d). The cyclization of compounds2,3, and4in the presence of 2N NaOH resulted in the formation of compounds2e-4econtaining two or three [1,2,4]triazole rings which are linked to the benzene ring. These compounds are important and useful monomer for synthesis of various dendrimers.

Disubstituted thiourea derivatives and their activity on CNS: synthesis and biological evaluation

A series of new thiourea derivatives of 1,2,4-triazole have been synthesized. The difference in structures of obtained compounds are directly connected with the kind of isothiocyanate (aryl/alkyl). The (1)H NMR, (13)C NMR, MS methods were used to confirm structures of obtained thiourea derivatives. The molecular structure of (1, 17) was determined by an X-ray analysis. Two of the new compounds (8 and 14) were tested for their pharmacological activity on animal central nervous system (CNS) in behavioural animal tests. The results presented in this work indicate the possible involvement of the serotonergic system in the activity of 8 and 14. In the case of 14 is also a possible link between its activity and the endogenous opioid system. All obtained compounds were tested for antibacterial activity against gram-positive cocci, gram-negative rods and antifungal activity. Compounds (1, 2, 5, 7, 9) showed significant inhibition against gram-positive cocci. Microbiological evaluation was carried out over 20 standard strains and 30 hospital strains. Selected compounds (1-13) were examined for cytotoxicity, antitumor, and anti-HIV activity.

Synthesis and evaluation of antitumor activities of novel chiral 1,2,4-triazole Schiff bases bearing γ-butenolide moiety

BACKGROUND

1,2,4-Triazole derivatives have received much attention due to their versatile biological properties including antibacterial, antifungal, anticonvulsant, antiinflammatory, anticancer, and antiproliferative properties. 1,2,4-Triazole nucleus has been incorporated into a wide variety of therapeutically interesting molecules to transform them into better drugs. Schiff bases of 1,2,4-triazoles have also been found to possess extensive biological activities. On the other hand, γ-substituted butenolide moiety represents a biological important entity that is present in numerous biologically active natural products.

RESULTS

We have described herein the synthesis of 12 hybrid 1,2,4-triazole Schiff bases bearing γ-substituted butenolide moiety. These compounds were synthesized by utilizing the tandem asymmetric Michael addition/elimination reaction as the key step. All the new compounds were evaluated for their in vitro anticancer activity.

CONCLUSIONS

Tandem asymmetric Michael addition/elimination approach has offered an easy access to new chiral 1,2,4-triazole compounds 7a-7l. All these chiral 1,2,4-triazole derivatives exhibited good anticancer activities towards Hela. Of all the tested compounds, the chiral compound 7l with an IC50 of 1.8 μM was found to be the most active.

Synthesis Using Microwave Irradiation, Characterisation and Antibacterial Activity of Novel Deoxycholic Acid-Triazole Conjugates

Novel deoxycholic acid 3α-triazole conjugates based on methyl 3α-chloroacetoxy-12α-hydroxy-cholanate have been synthesised. The synthesis is accelerated by microwave irradiation under solvent free conditions in the presence of K2CO3. Some of these compounds were tested for antibacterial activity against B.subtilis, P.aeruginosa and S.aureus. The preliminary results indicated that these deoxycholic acid-triazole conjugates have good inhibitory effect against B.subtilis. All of the compounds were characterised by 1H NMR, IR, ESI-MS spectra and elemental analyses.

Regioselective reaction: synthesis, characterization and pharmacological activity of some new Mannich and Schiff bases containing sydnone

A novel series of 1-substituted aminomethyl-3-[1-(4-isobutylphenyl)ethyl]-4-(3-aryl-4-sydnonylidene) amino-1,2,4-triazol-5-thiones (9), was prepared from the 3-[1-(4-isobutylphenyl)ethyl]-4-(3-aryl-4-sydnonylidene) amino 5-mercapto-1,2,4-triazoles (8) by aminomethylation with formaldehyde and secondary amine. The structures of Schiff bases (8) and Mannich bases (9) were characterized on the basis of IR, NMR, mass spectra1 data and elemental analysis. The newly synthesized compounds were screened for their anti-inflammatory and analgesic activities. Mannich bases (9) carrying piperidine and morpholine residues showed promising anti-inflammatory and analgesic activity.

4-({(E)-[2-(But-3-en-1-yl)-1-(prop-2-en-1-yl)-4-sulfanyl-1H-imidazol-5-yl]methyl-idene}amino)-3-phenyl-1H-1,2,4-triazole-5(4H)-thione

In the title compound, C₁₉H₂₀N₆S₂, the dihedral angle between the phenyl and triazole rings is 24.1 (2)° while the dihedral angles between the imidazole ring and the triazole and phenyl rings are 39.9 (2) and 55.3 (2)°, respectively. The crystal structure is stabilized by inter­molecular N—H⋯N hydrogen bonds which form chains along [10].

Synthesis under microwave irradiation of [1,2,4]triazolo[3,4-b] [1,3,4]thiadiazoles and other diazoles bearing indole moieties and their antimicrobial evaluation

Microwave-assisted synthesis of some novel compounds, namely, 3-(2-methyl-1H-indol-3-yl)-6-aryl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles 5a,b was accomplished via bromination of 2-methyl-3-[4-(arylideneamino)-5-mercapto-4H-[1,2,4]triazol-3-yl]-1H-indoles 3a,b. Also, new [1,3,4]thiadiazoles 12a,b, [1,2,4]triazoles 15a,b and [1,3,4]oxadiazoles 19a,b, with indole moieties, were prepared by cyclization of 1-[(2-methyl-1H-indole)-3-carbonyl]thiosemicarbazides 8a,b under microwave irradiation using different reaction conditions. Moreover, reaction of acid hydrazide 7 with ethyl 2-(N-phenylhydrazono)-3-oxobutanoate (20) gave the respective phenylhydrazonopyrazole derivative 21 under the reaction conditions employed. The structures of the synthesized compounds were assigned based on elemental analyses and spectral data (IR, (1)H-NMR, (13)C-NMR, MS). The antifungal and antibacterial activities of the new products were also evaluated.

Synthesis and antioxidant evaluation of some new 3-substituted coumarins

3-Acetylcoumarin (1) was utilized as a key intermediate for the synthesis of 2-aminothiazole derivative 3 via bromination of 1 to afford acetylbromide 2 followed by treatment with thiourea or via Biginelli reaction of 1. Treatment of 3 with 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde, 2-methyl-4H-benzo[d][1,3]oxazin-4-one, furo[3,4-b]pyrazine-5,7-dione or 2-methyl-5,6,7,8-tetrahydro-4H-benzothieno[2,3-d][1,3]oxazin-4-one afforded diazine derivatives 4-7. Also, pyridopyrimidine 8 was obtained via a one pot reaction of 6-aminothiouracil, p-chlorobenzaldehyde and 3-acetylcoumarin. Moreover, refluxing of 6-aminothiouracil with one equivalent amount of 2 afforded the thiazolopyrimidine 9, while the pyrrolothiazolopyrimidine 10 was revealed when two equivalent amounts of 2 was used. Furthermore, treatment of enamine 11 with 2-aminobenzothiazole or 6-aminothiouracil afforded the pyrimidine derivatives 12 and 13, respectively. Transamination of enamine 11 with m-anisidine followed by cyclization of the resulting enaminone 14 gave the desired quinoline 15. Also, treatment of 11 with thiophenol in dioxane gave the mercapto derivative 16. Moreover, coupling of 11 with 4,6-dimethyl-1H-pyrazolo[3,4-b]pyridin-3-yl-diazonium chloride, followed by complete cyclization of the resulting product afforded the pyridopyrazolothiazine 19 via the intermediate 18. Furthermore, the pyrazolopyrimidine 20 was revealed via a one pot condensation of 11, 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one and ammonium acetate. The thiadiazine derivatives 21-23 were obtained via treatment of 2 with the corresponding o-aminothiols. Desulphonation of 23 afforded the pyrazolotriazine 24. Finally, reaction of 2 with 2-hydroxybenzaldehyde gave benzofuran derivative 25. Representative compounds of the synthesized products were evaluated as antioxidant agents.

Anti-inflammatory and antinociceptive evaluation of newly synthesized 4-(substituted ethanoyl) amino-3-mercapto-5-(4-methoxy) phenyl-1,2,4-triazoles

Introduction:

1,2,4-triazoles and its derivatives have been reported to possess anti-inflammatory, analgesic, antimicrobial, anticancer, antitumor, antitubercular, anticonvulsant, openers of Ca-activated potassium (Maxi-K) channels, antiviral properties, hypoglycemic, anxiolytic and antidepressant activity. Therefore, 1,2,4-triazole seems to be an important pharmacophore.

Materials and Methods:

The synthesis of 4-(substituted ethanoyl) amino-3-mercapto-5-(4-methoxy) phenyl-1,2,4-triazoles (6a-o) were prepared following six step starting 4-methoxy benzoic acid and using different secondary amines and were characterized with the help of FT-IR,¹H,¹³C NMR, FAB Mass and nitrogen analysis. These synthesized compounds (6a-o) were then evaluated for anti-inflammatory activity by carrageenan induced paw edema method.Out of these synthesized compounds, some (6f, i and k) were evaluated for antinociceptive activity by Hot plate method and Tail immersion method.

Results and Discussion:

The synthesis of 4-(substituted amino)-3-mercapto-5-(4-methoxy) phenyl-1,2,4-triazoles (6a-o) was accomplished. The IR spectra exhibited characteristic bands for C-N, C=N, SH and C=O at 1350-1360, 1511-1548, 2520-2594.3 and 1650-1719 cm^-1. The C-O-C asymmetric and symmetric str. was at 1250-1254 and 1027-1079.3 cm^-1 respectively. In¹H-NMR spectra, a singlet of CONH was found in the range of δ 9.92-10.18 ppm and another singlet of thiol group was observed in the range of δ 8.63-9.92 ppm. A singlet of Ar-OCH₃ was also found between δ 3.57-3.91 ppm. In¹³ C- NMR spectra, C-3 and C-5 of the 1,2,4 - triazole nucleus were observed in the range of δ 147-166.9 ppm. Carbonyl carbon and methylene carbon of –NHCOCH₂ N< were found between δ 166.5-177.5 and δ 47.1-62 ppm respectively. Acute toxicity study was donr following OECD-423 and cut-off dose was found to be between 1000-1500 mg/kg body weight. At the dose level of 100 mg/kg, 6f, 6i and 6k exhibited appreciable inhibition of oedema especially 6k exhibiting a percentage of oedema inhibition of 40.28%, which was comparable to that of the standard drug indomethacin (62.50% at 10mg/kg dose). Among the compounds tested, compound 6k exhibited good anti-nociceptive activity in both methods used. Pethidine (20mg/kg body weight s.c) is used as the standard drug.

Conclusion:

SAR of these synthesized compounds shows that substitution with heterocyclic moiety at C-2 of the acetamido group at position 4 of the 1,2,4-triazole produces appreciable activity as compared to substitution with aliphatic moieties since among all the synthesized compounds, the most active ones are 6f, 6i and 6k that have piperdine, 1-benzyl piperazine and morpholine group, respectively at C-2 of the acetamido group at position 4 of the 1,2,4-triazole.

Synthesis and Characterisation of Novel 1,3-Bis{(6-Aryl-1,2,4-Triazolo [3,4-b][1,3,4]Thiadiazol-3-yl)-Methoxy}benzenes under Microwave Irradiation

Eleven novel 1,3-bis{(6-aryl-1,2,4-triazolo[3,4-b][1,3,4]thiadiazol-3-yl)-methoxy}benzenes have been synthesised in high yields by the condensation of 5,5'-[1,3-phenylene-bis(oxymethylene)]bis(4-amino-3-mercapto-1,2,4-triazole) with substituted benzoic acids in the presence of phosphorus oxychloride under microwave irradiation. Compared with the conventional heating method, this method is facile, rapid and efficient. The structures of all new compounds were characterised by 1H NMR, IR, MS and elemental analysis.

Synthesis of Novel Triazole Derivatives of Methyl 3-Oxocholanate Using Microwave Irradiation

An efficient rapid method for the synthesis of new triazole derivatives derived from methyl 3-oxocholanate under microwave irradiation has been developed. These new compounds were characterised by 1H NMR, IR, ESI-MS spectra and elemental analyses. Some of these triazoles were tested for antibacterial activity against Staphylococcus aureus, Candida albicans and Escherichia coli.

Synthesis of 3-((2,4-dichlorophenoxy)methyl)-1,2,4-triazolo(thiadiazoles and thiadiazines) as anti-inflammatory and molluscicidal agents

A series of fused and non fused 1,2,4-triazoles with (2,4-dichlorophenoxy) moiety are prepared utilizing 3-((2,4-dichlorophenoxy)methyl)-4-amino-4H-1,2,4-triazole-5-thiol (3). The latter on reaction with carboxylic acids, ethylchloroformate, ethylcyanoacetate and sodium nitrite gives five membered fused triazole derivatives 4a-d, 5, 6, 7 and 10, respectively. The six membered heterocycles 11, 12 and 14 are prepared by cyclization of compound 3 with phenacyl bromide, chloroacetic acid and alpha-bromoketone respectively. Most of the newly synthesized compounds were screened for their anti-inflammatory and molluscicidal activities. The compounds 4b, 4d, 11 and 14 showed potent anti-inflammatory activities in dose dependent manner while compounds 3, 4b, 8 and 10 exhibited promising molluscicidal activities.