Comprehensive review in current developments of imidazole-based medicinal chemistry

Regioselective Synthesis of Highly Substituted Imidazoles via the Sequential Reaction of Allenyl Sulfonamides and Amines

A novel synthesis of imidazoles from electron-withdrawing group-substituted allenyl sulfonamides with amines was developed. The 4- and 5-functionalized imidazoles were constructed regioselectively, which depended on the substituents on the nitrogen atoms.

Diazole-based powdered cocrystal featuring a helical hydrogen-bonded network: structure determination from PXRD, solid-state NMR and computer modeling

We present the structure of a new equimolar 1:1 cocrystal formed by 3,5-dimethyl-1H-pyrazole (dmpz) and 4,5-dimethyl-1H-imidazole (dmim), determined by means of powder X-ray diffraction data combined with solid-state NMR that provided insight into topological details of hydrogen bonding connectivities and weak interactions such as CH···π contacts. The use of various 1D/2D (13)C, (15)N and (1)H high-resolution solid-state NMR techniques provided structural insight on local length scales revealing internuclear proximities and relative orientations between the dmim and dmpz molecular building blocks of the studied cocrystal. Molecular modeling and DFT calculations were also employed to generate meaningful structures. DFT refinement was able to decrease the figure of merit R(F(2)) from ~11% (PXRD only) to 5.4%. An attempt was made to rationalize the role of NH···N and CH···π contacts in stabilizing the reported cocrystal. For this purpose four imidazole derivatives with distinct placement of methyl substituents were reacted with dmpz to understand the effect of methylation in blocking or enabling certain intermolecular contacts. Only one imidazole derivative (dmim) was able to incorporate into the dmpz trimeric motif thus resulting in a cocrystal, which contains both hydrophobic (methyl groups) and hydrophilic components that self-assemble to form an atypical 1D network of helicoidal hydrogen bonded pattern, featuring structural similarities with alpha-helix arrangements in proteins. The 1:1 dmpz···dmim compound I is the first example of a cocrystal formed by two different azoles.

H-ZSM-5 Zeolite Synthesis by Sourcing Silica from the Wheat Husk Ash: Characterization and Application as a Versatile Heterogeneous Catalyst in Organic Transformations including Some Multicomponent Reactions

ZSM-5 zeolite was synthesized by sourcing silica from wheat husk ash and was converted into its protonated form following careful, conventionally accepted ion-exchange method and calcinations. The H-ZSM-5 zeolite (Si/Al ratio = 30) prepared was appropriately characterized by XRD, FT-IR, SEM, TEM, TG-DTA, CV, and so forth, and evaluated as recyclable catalyst in selective organic transformations including three- and four-component reactions. The catalytic activity of the zeolite sample supposedly relates to increased density of the accessible acid sites.

Synthesis of novel sulfonamide azoles via C–N cleavage of sulfonamides by azole ring and relational antimicrobial study

Novel sulfonamide azoles were synthesizedviathe C–N cleavage of sulfonamides by an azole ring, and evaluated for their relational antimicrobial behaviors.

Design and synthesis of new fluconazole analogues

The synthesis of new fluconazole analogues containing two different 1,2,3-triazole units and an amide group is described. All the compounds showed very high antifungal activity and no toxicity.

Synthesis and biological evaluation of a new class of quinazolinoneazoles as potential antimicrobial agents and their interactions with calf thymus DNA and human serum albumin

A series of quinazolinone azoles were synthesized and screened for their antimicrobial activities, and further studies of their binding behaviors with calf thymus DNA and human serum albumin were investigated.

Design, synthesis, and antibacterial evaluation of novel azolylthioether quinolones as MRSA DNA intercalators

Synthesis of a series of azolylthioether quinolones as a new type of potential antimicrobial agents, and preliminary interactions with MRSA DNA indicated a possible interaction mechanism.

Metal-free synthesis of 3,5-disubstituted 1H- and 1-aryl-1H-pyrazoles from 1,3-diyne-indole derivatives employing two successive hydroaminations

The uncatalyzed synthesis of 3,5-disubstituted 1H- and 1-aryl-1H-pyrazoles derived from 1,3-diyne indoles was successfully carried out in PEG 400. The scope and limitations of the reaction were studied.

Metal/organo relay catalysis in a one-pot synthesis of methyl 4-aminopyrrole-2-carboxylates from 5-methoxyisoxazoles and pyridinium ylides

Methyl 4-aminopyrrole-2-carboxylates were easily synthesized by the reaction of 5-methoxyisoxazoles with phenacylpyridinium salts under hybrid relay catalysis leading to 1-(5-methoxycarbonyl-1H-pyrrol-3-yl)pyridinium salts followed by a one pot Zincke cleavage.

Synthesis of tetrazole compounds as a novel type of potential antimicrobial agents and their synergistic effects with clinical drugs and interactions with calf thymus DNA

A series of tetrazole derivatives were synthesized and characterized by NMR, IR, MS and HRMS spectroscopy.

Crystal structure of 2-{[1-(2-methyl-5-nitro-1H-imidazol-1-yl)propan-2-yl-oxy]carbon-yl}benzoic acid

In the title compound, C15H15N3O6, the dihedral angle between the planes of the benzene and imidazole rings is 34.93 (10)°. An intra-molecular C-H⋯O hydrogen bond is observed. In the crystal, O-H⋯N hydrogen bonds link the mol-ecules into chains parallel to the c axis.

Analysis of the structural diversity, substitution patterns, and frequency of nitrogen heterocycles among U.S. FDA approved pharmaceuticals

Nitrogen heterocycles are among the most significant structural components of pharmaceuticals. Analysis of our database of U.S. FDA approved drugs reveals that 59% of unique small-molecule drugs contain a nitrogen heterocycle. In this review we report on the top 25 most commonly utilized nitrogen heterocycles found in pharmaceuticals. The main part of our analysis is divided into seven sections: (1) three- and four-membered heterocycles, (2) five-, (3) six-, and (4) seven- and eight-membered heterocycles, as well as (5) fused, (6) bridged bicyclic, and (7) macrocyclic nitrogen heterocycles. Each section reveals the top nitrogen heterocyclic structures and their relative impact for that ring type. For the most commonly used nitrogen heterocycles, we report detailed substitution patterns, highlight common architectural cores, and discuss unusual or rare structures.

Novel hybrids of metronidazole and quinolones: synthesis, bioactive evaluation, cytotoxicity, preliminary antimicrobial mechanism and effect of metal ions on their transportation by human serum albumin

A novel series of hybrids of metronidazole and quinolones as antimicrobial agents were designed and synthesized. Most prepared compounds exhibited good or even stronger antimicrobial activities in comparison with reference drugs. Furthermore, these highly active metronidazole-quinolone hybrids showed appropriate ranges of pKa, log P and aqueous solubility to pharmacokinetic behaviors and no obvious toxicity to A549 and human hepatocyte LO2 cells. Their competitive interactions with metal ions to HSA revealed that the participation of Mg(2+) ion in compound 7d-HSA association could result in a concentration increase of free compound 7d. Molecular modeling and experimental investigation of compound 7d with DNA suggested that possible antibacterial mechanism might be in relation with multiple binding sites between bioactive molecules and topo IV-DNA complex.

Synthesis and antimicrobial activity of novel 5-aminoimidazole-4-carboxamidrazones

A mild and simple method was developed to prepare a series of fifteen 5-aminoimidazole 4-carboxamidrazones, starting from the easily accessible 5-amino-4-cyanoformimidoyl imidazoles. The antimicrobial activity of these novel amidrazones was screened against Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli, Pseudomonas aeruginosa) bacteria and Candida sp. (Candida albicans, Candida krusei, Candida parapsilosis). Only a subset of compounds displayed fair-moderate activity against S. aureus and E. coli but all exhibited activity against Candida sp. The three most potent antifungal compounds were further tested against Cryptococcus neoformans, Aspergillus fumigatus and three dermatophytes (Trichophyton rubrum, Trichophyton mentagrophytes, Microsporum gypseum). These three hit compounds strongly inhibited C. krusei and C. neoformans growth, although their activity on filamentous fungi was very weak when compared to the activity on yeasts.

Synthesis and bioactive evaluation of a novel series of coumarinazoles

A series of novel coumarinazoles were designed, synthesized, and characterized by IR, NMR, MS and HRMS spectra. The bioactive assay for the newly prepared compounds against six bacteria and five fungi manifested that most new compounds exhibited good or even stronger antibacterial and antifungal activities in comparison with reference drugs Chloromycin, Norfloxacin and Fluconazole. Bis-azole alcohols 7a and 7d-e showed better anti-Candida utilis activity than mono-azole derivatives 4a and 4d-e at the tested concentrations, and they were more potent than the clinical Fluconazole. While triazole alcohol 7a gave comparable anti-Candida albicans and anti-Candida mycoderma activity to Fluconazole and better anti-MRSA activity than mono-triazole one 4a and clinical Norfloxacin. 1H-Benzoimidazol-2-ylthio coumarin derivatives 4e and 7e gave the strongest anti-Escherichia coli JM109 efficacy. Oxiran-2-ylmethoxy moiety was found to be a beneficial fragment to improve antibacterial and antifungal activity to some extent.

A simple approach to pyrrolylimidazole derivatives by azirine ring expansion with imidazolium ylides

Versatile synthesis of 1-(1H-pyrrol-3-yl)-1H-imidazole derivatives by a domino reaction of 2H-azirines with 1-alkyl-3-phenacyl-1H-imidazolium bromides is reported.

Alkaline earth catalysis for the 100% atom-efficient three component assembly of imidazolidin-2-ones

A variety of functionalised imidazolidin-2-ones may be synthesised under very mild reaction conditions using non-toxic and cost-effective alkaline earth bis(amide) pre-catalysts in a 100% atom-efficient, intermolecular one-pot assembly from inexpensive alkyne and cumulene reagents.

Synthesis and biological evaluation of α-triazolyl chalcones as a new type of potential antimicrobial agents and their interaction with calf thymus DNA and human serum albumin

A series of α-triazolyl chalcones were efficiently synthesized. Most of the prepared compounds showed effective antibacterial and antifungal activities. Noticeably, α-triazolyl derivative 9a exhibited low MIC value of 4 μg/mL against MRSA and Micrococcus luteus, which was comparable or even superior to reference drugs. The further research revealed that compound 9a could effectively intercalate into Calf Thymus DNA to form 9a-DNA complex which might block DNA replication to exert their powerful antimicrobial activities. Competitive interactions between 9a and metal ions to Human Serum Albumin (HSA) suggested the participation of Fe(3+), K(+) and Mg(2+) ions in 9a-HSA system could increase the concentration of free 9a, shorten its storage time and half-life in the blood, thus improving its antimicrobial efficacy.