Synthesis and Reactivity of Phenylthiourea Derivatives: An Efficient Synthesis of New Thiazole‐Based Heterocycles

Reaction of 1‐(5‐acetyl‐4‐methylthiazol–2‐yl)–3‐phenylthiourea 2 with hydrazonoyl chlorides ( 3a , 3b , 3c , 3d , 3e , 3f ) and 9 yielded the corresponding (thiazolyl)imino–1,3,4‐thiadiazole derivatives ( 6a , 6b , 6c , 6d , 6e , 6f ) and 12 , respectively. Reaction of 2 with ethyl chloroacetate 13 gave (thiazolyl)imino‐1,3‐thiazolidin‐4‐one derivative 15 , which upon condensation with aromatic aldehyde derivatives yielded the 5‐benzylidene derivatives ( 16a , 16b ). In addition, treatment of 2 with 3‐chloropenta‐2,4‐dione 17 afforded the corresponding (thiazolyl)imino‐1,3‐thiazole derivative 19 . The newly synthesized compounds were confirmed from their elemental analyses and spectral data.     

Synthesis of New Polyheterocyclic Compounds Based on Chalcones

Russian Journal of Organic Chemistry - The reaction of methyl N-{4-[2-(2-oxo-2,3-dihydro-1H-indol-3-ylidene)acetyl]phenyl}carbamate with tosylmethyl isocyanide in tetrahydrofuran in the presence of...     

A Facile Three‐Component One‐Pot Synthesis of Some Novel Tricyclic Hetero‐Ring Systems

A novel, facile, one‐pot, multicomponent reaction for the synthesis of a series of pyrano[2,3‐d][1,2,4]triazolo[4,3‐a]pyrimidine and pyrano[2′,3′:4,5]pyrimido[2,1‐b][1,3,5]thiadiazine derivatives has been developed from reaction of 2,4‐dichlorobezaldehyde, malononitrile, and the appropriate active methylene compounds in refluxing dioxane in the presence of chitosan. A plausible mechanism has been proposed for this reaction, and the structure of the newly synthesized compounds was all established on the basis of spectral data (mass, IR, and ¹H‐NMR) and elemental analyses.     

Convenient One Pot Synthesis and Antibacterial Evaluation of Some New Mannich Bases Carrying 1,2,4‐Triazolyl Moiety

A series of Mannich bases were synthesized by a three‐component Mannich reaction. The newly synthesized compounds were well characterized by elemental analyses, IR, NMR and mass spectroscopic studies. The potential antibacterial effects of the synthesized compounds were investigated using standard bacterial strains: Gram‐positive and Gram‐negative bacteria. Interestingly, all the synthesized compounds were observed to be promising leads, possessing moderate to significant inhibitory activity as compared to standard.     

Synthesis and Antibacterial Activity of Some New 2,5‐Disubstituted‐1,3,4‐oxadiazole Derivatives

Synthesis of some new oxadiazole derivatives starting from 1,2,3-benzo[d]triazole-1-acetic hydrazide (1) is described. The target compounds 2-(N-substituted-aminocarbonylmethylthio)-5-(1,2,3-benzo[d]triazol-1-ylmethyl)- 1,3,4-oxadiazole (4a—4i) and 2-[2-(N-substituted-aminocarbonyl)ethylthio]-5-(1,2,3-benzo[d]triazol-1-ylmethyl)- 1,3,4-oxadiazole (5a—5i) were obtained in good yields via cyclisation of 1 and subjected to antibacterial activity test against pathogenic bacteria. The halogen containing mono- and di-substituted derivatives showed excellent antibacterial activity compared to other analogues.     

Ligand‐Directed Divergent Synthesis of Carbo‐ and Heterocyclic Ring Systems

Chemical tools that enable a catalytic reaction to selectively and efficiently yield different products will allow charting of wider chemical space. In ligand‐directed divergent synthesis, a common mode of catalysis is modulated by employing different ligands for catalytic organometallic complexes to transform either common substrates or common reactive intermediates into distinct molecular scaffolds. The strategy has the potential to create important and diverse scaffolds and to unveil novel modes of catalytic transformations for wider synthetic applications. This strategy is described and recent efforts in this emerging field of catalysis, focusing on transition‐metal catalysis for the synthesis of carbo‐ and heterocyclic ring systems, are reviewed.     

Design and Synthesis of Some New Quinoxaline‐Based Heterocycles

Considering quinoxaline as a privileged structure for developing probes of impressive therapeutic potentials, some new azole and azine conjugates of quinoxaline were synthesized. Thus, ethyl 3‐amino‐1,4‐dihydroquinoxaline‐2‐carboxylate ( 2 ) was prepared as one‐pot three‐component product and incorporated in a series of manipulations including cyclocondensation reactions to afford a series of pharmacophoric motif conjugates 8–12 , 14, 15–17 , 20–23 , 24–29 , 30 – 37 , and 38–43 in fair yields. The newly synthesized were characterized by IR, ¹H NMR, ¹³C NMR, and mass spectral data.     

Synthesis and Antibacterial Evaluation of Some Semicarbazides and 1,2,4‐Triazol‐5‐Ones Containing Thiophene Moieties

In this study, some 3‐(thiophen‐2‐ylmethyl)‐4‐substituted‐4,5‐dihydro‐1H‐1,2,4‐triazol‐5‐one derivatives were synthesized by the cyclization reaction of 1‐(thiophen‐2‐ylacetyl)‐4‐substituted semicarbazide derivatives in alkaline medium or in the immediate reaction of thiophen‐2‐yl‐acetic acid hydrazide with isocyanates. The structures of all new compounds were confirmed by analytical and spectroscopic methods. Selected derivatives were evaluated in vitro against several species of aerobic bacteria. Some of them showed activity against S. pyogenes, P. aeruginosa and S. aureus.     

An Easy Access to Construct Some New Fused 1,2,4‐Triazines with Ring Junction Nitrogen Systems and Their Biological Evaluation

The chemical reactivity of 4‐amino‐6‐benzyl‐3‐mercapto‐1,2,4‐triazine‐5(4H )‐one ( 1 ) towards various aliphatic or/and mono and bis aromatic carboxylic acid derivatives to give the corresponding fused heterocyclic systems, 1,3,4‐thiadiazoles 4 , 5 , 6 , which incorporating 1,2,4‐triazine moiety was achieved. Moreover, compound 1 was subjected to reaction either with halo acetic acids or bromo ester to afford the respective fused nitrogen ring junction systems, thiadiazole 2 and 3 or thiadiazine 7 . However, while the tetracyclic ring system 9 was furnished through condensation reaction of isatine with triazine 1 . In addition, some of the new synthesized compounds were evaluated as an antioxidant and antitumor agents.     

Copper‐Catalyzed Annulation of 2‐Formylazoles with Aminoiodopyrazoles: Synthesis of New Heterocyclic Ring Systems

Various 2‐formylazoles underwent CuI/sparteine‐catalyzed annulation with 1‐substituted‐4‐iodo‐5‐aminopyrazoles to produce four new heterocyclic ring systems. The reaction was demonstrated for 2‐formylpyrroles, 2‐formylindoles, 2‐formylimidazole, and 3‐methyl‐5‐formylpyrazole. 3‐Substitution of the iodopyrazole was tolerated.     

Synthesis and Antimicrobial Evaluation of Some New 4,5′‐Bisthiazoles

Thiazole and bisthiazole derivatives represent a prevalent scaffold in the antimicrobial drug discovery. Therefore, we have decided to synthesize some new series of 4,5′‐bisthiazoles. A total of 17 compounds were synthesized, their structural elucidation being based on elemental analysis (C,H,N,S) and spectroscopic data (MS and ¹H NMR). Their in vitro antimicrobial activities were assessed against several Gram‐positive and Gram‐negative bacteria strains and also against one fungal strain (Candida albicans) using the difusimetric method. Some of the compounds showed modest to good antibacterial activity against Gram‐negative Escherichia coli and Salmonella typhimurium and Gram‐positive Staphylococcus aureus and Bacillus cereus bacterial strains. All of the synthesized compounds showed moderate to very good antifungal activity against C. albicans.     

Synthesis,Characterization, and Pharmacological Evaluation of Some New Pteridine‐Based Heterocycles as Antimicrobial Agents

Considering pteridine as a worthy structure for improving probes of magnificent therapeutic potentials, some new pteridine conjugates were synthesized by aminomethylation of benzopteridinethione with a variety of primary aromatic amines and formaldehyde solution (37%) through the Mannich reaction. The proposed mechanism of formation of the synthesized compounds was discussed, and the structure of the newly synthesized compounds was elucidated on the basis of their IR, ¹H NMR, ¹³C NMR, mass spectral, and elemental analyses. Furthermore, some selected compounds were evaluated in vitro for their antimicrobial activities; the preliminary data stated that the majority of the tested compounds exhibited significant antimicrobial activity. Analogues 22 , 23 , 20 , 19 , 24 , and 15 were found to be the most potent against all the tested microorganisms.     

Synthesis and Antibacterial Activity of Some New S-Triazole Derivatives

Abstract

Alkylation of 4-anilino-5-phenyl-4H-1,2,4-triazole-3-thiol (1) with some halo compounds yielded the corresponding sulfides 2a–f. Some sulfides 2e,f were cyclized to give triazolothiadiazines 3 and 4. Triazolothiadiazoles 5 and 6 were prepared through the reaction of compound 1 with carbon disulfide or ethyl orthoformate, respectively. Treatment of compound 1 with ethyl chloroformate or phenyl isothiocyanate yielded triazolo-thiadiazole and triazole 9 and 10, respectively. Reaction of compound 1 with Lawesson's reagent gave triazolothiadiazaphosphole derivative 11. Also, compound 1 underwent cyclocondensation reactions with some bidentate reagents to give triazolothiazines 4, 12, and 13. Triazolo-thiazepines and triaziepine 14–16 were synthesized via the reaction of compound 1 with β-ketoesters or ethyl cyanoacetate. Tricyclic systems 19 and 20 were prepared through the reaction of compound 4 with the appropriate reagent. Some synthesized compounds were tested for antibacterial activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Formation of Some New Four-Memberd Phosphorus-Nitrogen and Phosphorus-Nitrogen-Sulfur Ring Systems

Abstract

Continuing the study on the course of reaction of Py·PS₂Cl with primary amines we have found a method to prepare the hitherto unknown tetrathio-substituted phosphetidine compounds 1 and 2. Primary amines react with Py·PS₂Cl in a molar ratio of 1:l in the presence of a base either to diazaphosphetidines 1 or to azathiaphosphetidines 2 according to equation (1):     

Microwave‐Assisted Rapid and Efficient Synthesis of New Series of Chromene‐Based 1,2,4‐Oxadiazole Derivatives and Evaluation of Antibacterial Activity with Molecular Docking Investigation

A new series of novel chromene‐based oxadiazole derivatives were synthesized from a variety of chromene‐based amidoximes with readily available carboxylic acids under conventional oil bath heating as well as under microwave irradiation. The use of commercially available EDCI and HOBt as coupling reagents in DMF combined with microwave heating resulted in high yields and purities of the product 1,2,4‐oxadiazoles in an expeditious manner. This methodology is successfully applied to synthesize 18 numbers of new 2H‐chromene‐substituted 1,2,4‐oxadiazole derivatives in good to high yields. The structure of the product was ascertained by X‐ray crystallographic analysis. All the synthesized compounds were evaluated for their in vitro antibacterial activity against two different pathogenic bacterial strains, that is, Escherichia coli (MTCC614) and Klebsiella pneumoniae (MTCC4031). The obtained results from in vitro antimicrobial assays indicated that 6g and 6h exhibited good antibacterial activity nearer to the standard drug, gentamicin. The molecular docking studies showed that compounds 6g and 6h show hydrogen bonding interaction with the bacterial target DNA gyrase of E. coli.     

Synthesis and Antibacterial Assay of Some New Pyrenyl Pyridine Candidates

Russian Journal of General Chemistry - Novel polycyclic compounds, 1-pyrene-based pyridone derivatives, are synthesized by treatment of pyrenyl acetohydtazide with several arylidenemalononitriles...     

Synthesis of Some Novel Furan‐tagged Thienopyrimidine Derivatives as Antibacterial Agents

Cyclization of 2‐furan‐2‐yl‐4‐mercapto‐6‐methylpyrimidine‐5‐carbonitrile 1 with ethyl chloroacetate gave o‐aminoester thienopyrimidine derivative 3 , which was reacted with a variety of reagents to give a series of novel thienopyrimidines including tetrazolyl thienopyrimidine, pyrrolylthienopyrimidine, pyrimidothienotriazine, and thienodipyrimidines. Some of the synthesized compounds were tested for their antibacterial activities against Gram‐positive and Gram‐negative bacteria.     

Synthesis and Antibacterial Activity of Some 3,5‐Diphenyl and 1,3,5‐Triphenyl‐2‐pyrazolines

Some new 3,5‐diphenyl and 1,3,5‐triphenyl‐2‐pyrazolines derivatives were synthesized by reacting 1,3‐diphenyl‐2‐propen‐1‐ones with hydrazine hydrates and phenyl hydrazine in ethanol. The structural elucidation of the compounds was performed by IR, ¹H NMR and elemental analysis. All examined compounds showed appreciable antibacterial activity.