Preparation of pyridopyrazines through tandem Pd-catalyzed C-N/C-C coupling reactions of Ugi adducts.

A Pd-catalyzed selective tandem cyclization of the Ugi adduct via Buchwald-Hartwig/C-H bond functionalization reactions has been reported. This sequence offers an interesting approach for synthesizing a wide range of pyrido[1,2-a]pyrazine-3,6-dione scaffolds under mild reaction conditions in moderate to excellent yields. The scope and limitations of the protocol are discussed.

Nitroepoxide ring opening with thionucleophiles in water: synthesis of α-xanthyl ketones, ß-keto sulfones and ß-keto sulfonic acids.

Nitroepoxide ring opening with thionucleophiles such as potassium xanthates, sodium aryl sulfinates and sodium bisulfite in water is investigated. It provides a direct and green route for the synthesis of α-xanthyl-α-aryl-2-propanones (P2P-xanthate derivatives), ß-keto sulfones and ß-keto sulfonic acids. High to excellent yields, performing the reaction in water under catalyst-free conditions, and easy work-up are the main advantages of this protocol.

Controlled Release of Aspirin in the Body using Pectin-coated ZIF-8 Nanoparticles.

INTRODUCTION: Zeolitic imidazolate frameworks (ZIFs) play a crucial role among metalorganic frameworks due to their highly desirable properties, including high surface area, appropriate pore size, and excellent thermal and chemical stability. METHOD: In this study, ZIF-8 loaded with aspirin and coated using pectin (ZIF-8/Asp@Pectin) was utilized as a suitable and effective platform for the drug delivery system. The preparation of this coated MOF followed environmentally friendly methods, and aspirin was successfully loaded. RESULT: Characterization of the obtained ZIF-8/Asp@Pectin was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), Fourier Transform Infrared (FT-IR) spectroscopy, and BET analysis. CONCLUSION: The release of aspirin from ZIF-8/Asp@Pectin was studied using UV-Vis spectroscopy at 258 nm under in vitro conditions in HCl and PBS buffer solutions.

Development and synthesis of a novel salen-type ligand based on phenylalanine for Mizoroki-Heck, and S-arylation cross-coupling reactions.

In this article, we introduced a novel salen-type ligand precursor and applied it in the Pd-catalyzed Mizoroki-Heck and Cu-catalyzed S-arylation cross-coupling reactions. For the preparation of this structure, (DL)-phenyl alanine was employed as a starting material. These ligand precursor and related catalytic system can be readily synthesised. Various aryl halides (-I, -Br) and alkenes were applied successfully in this protocol to give the corresponding Mizoroki-Heck cross-coupling and S-arylated products in high to excellent yields.

Catalyst free one pot three components synthesis of 2-iminothiazoles from nitroepoxides and thiourea.

Nitroepoxides were introduced as efficient substrates for the one-pot three-component synthesis of 2-iminothiazoles under catalyst-free conditions. Reaction of amines, isothiocyanates, and nitroepoxides in THF at 10-15 °C afforded corresponding 2-iminothiazoles in high to excellent yields. The reaction proceeds via the in situ formation of thiourea from an amine and an isothiocyanate, followed by nitroepoxide ring opening with the sulfur of thiourea, cyclization reaction, and dehydration cascade. The structures of products were confirmed by IR, NMR, HRMS analyses and X-ray crystallography.

Novel uncharged triazole salicylaldoxime derivatives as potential acetylcholinesterase reactivators: comprehensive computational study, synthesis and in vitro evaluation.

The present study aims to design and synthesise novel uncharged aldoximes and explore their reactivation abilities, structures, descriptors, and mechanisms of action, as well as assessing the interactions and stabilities in the active site of paraoxon-inhibited acetylcholinesterase enzyme using computational studies and in vitro assay. The comprehensive computational studies including quantum chemical, molecular dynamics simulations and molecular docking were conducted on paraoxon-inhibited human acetylcholinesterase to investigate the reactivation ability of the novel aldoximes and compare them with pralidoxime as a reactivator model molecule.

Layered dermal reconstitution through epigallocatechin 3-gallate loaded chitosan nanoparticle within enzymatically crosslinked polyvinyl alcohol/collagen fibrous mat.

Biocompatible electrospun fiber comprising bioactive substrates has potential to implant into the wound site as a reliable therapeutic approach in tissue regeneration. Here, electrospun polyvinyl alcohol conjugated tyramine (PVA-Tyr) and collagen (Col) fibrous mat containing chitosan nanoparticle loaded with epigallocatechin 3-gallate (NCs-EGCG) developed and the composite was applied to evaluate in vivo wound healing ability of fabricated wound patch. The synthesized PVA-Tyr and Col were electrospun and crosslinked through peroxidase reaction in presence of vaporized H2O2 as an electron donor which covalently proceeded conjugation of phenolic groups and could develop hybrid fibrous mat in stable structure and uniform shapes. The EGCG as anti-oxidative/inflammatory substrate was encapsulated efficiently in NCs and released in a sustained manner. The hybrid fibers seeded with adipose-derived stem cells presented appropriate biocompatibility from biophysical and biochemical viewpoints and in following wound healing ability in a full-thickness excisional animal model. Fourier transform infrared spectroscopy (FTIR) confirmed all typical absorption characteristics of PVA-Tyr and Col as well as NCs and EGCG. The results showed the perfect hydrophilic/hydrophobic ratio and good mechanical and structural characteristics including shape uniformity and porosity. Interestingly, cellular attachment and proliferation on the PVA-Tyr/Col fibers containing NCs-EGCG were higher than control samples. The histological analysis of hybrid fibrous patch could be suggested the applicability of this structure as suitable skin substitutes to repair injured skin.

Bis[N-cyclohexyl-1-(2-{1-[(cyclohexyl-amino)carbonyl]cyclohexyl}-3,5-dioxo-1,2-oxazolidin-4-yl)cyclopentanecarbox-amide] monohydrate.

The reaction of cyclo-hexyl isocyanide and alkyl-idene Meldrum's acid (systematic name 2,2-dimethyl-1,3-dioxane-4,6-dione) in the presence of cyclo-hexyl ketoxime and dichloro-methane as solvent resulted in the title compound, 2C(28)H(43)N(3)O(5)·H(2)O. One methyl-ene group of the cyclo-pentane ring was found to be disordered and was refined with occupancies 0.75:0.25. Intra-molecular N-H⋯O hydrogen bonds occur. The crystal structure is stabilized by inter-molecular N-H⋯O and O-H⋯O hydrogen bonds.

Assembly of Indole Cores through a Palladium-Catalyzed Metathesis of Ar-X σ-Bonds.

We describe the development of a new method for construction of highly substituted indole scaffolds through the strategic utilizing of the metathesis of Ar-X σ-bonds based on the dynamic nature of palladium-based oxidative addition/reductive elimination. A suitable and simple catalytic system has provided an appropriate platform for a productive ligand exchange and consecutive carbopalladation/C-H activation/amination of phosphine ligands with alkynes and aromatic/aliphatic amines for construction of structurally diverse indoles.

A Fast Track to Indoles and Annulated Indoles through ortho- vs ipso-Amination of Aryl Halides.

A complementary site selective ortho- vs ipso-amination of aryl halides using non-electrophilic amine sources for construction of indole scaffolds is reported. A palladium-catalyzed alkyne insertion/C-H activation/palladacycle amination via merger of three easily diversified components including iodoarenes, alkynes, and amines delivers indoles with different substitution patterns even in gram scales. By employing ortho-bromoanilines, a consecutive annulative π-extension of indoles proceeds to construct indolo[1,2-f]phenanthridine scaffolds via four C-C and C-N bond formations in one pot.

Synthesis and Antimicrobial Evaluation of 4H-Pyrans and Schiff Bases Fused 4H-Pyran Derivatives as Inhibitors of Mycobacterium bovis (BCG).

The focus of our study is the synthesis and biological activity evaluation of a series of 4H-Pyran compounds and schiff bases fused 4H-Pyran derivatives which are known to possess a wide variety of biological activities. In this paper at first a simple and efficient one-pot synthesis of 4H-Pyran s from the three-component reaction between malononitrile, aldehydes, and active methylene compounds in the presence of N-methylmorpholine (NMM) as catalyst at room temperature is reported, the reaction between these synthesized products and trimethylorthoformateor triethylorthoformateto produce schiff base compounds were also considered. The key advantages of synthesis of 4H-Pyran derivatives are short reaction time, high yield, and simple work-up. Then, these compounds were evaluated for anti-Mycobacterium activity against Mycobacterium bovis (Bacillus Calmette-Guerin). The preliminary results indicated that most of the tested compounds showed relatively good activity against the test organism. Moreover, antifungal activities of these compounds were evaluated. Finally, their effect was more noticeable on Mycobacterium bovis (BCG).

Synthesis and fluorescence studies of nine 1,5-benzodiazepine-2,4-dione derivatives: Dual emission and excimer fluorescence.

The photophysical properties of nine 1,5-benzodiazepine-2,4-dione (BZD) derivatives were investigated using absorption and fluorescence spectral techniques in dimethyl sulfoxide. The trend of red shifts caused by the substitutions had full compliance with the trend of decreasing the calculated band gap (ΔELUMO-HOMO) by semi-empirical AM1 and DFT/B3LYP/6-311+G* computational methods. The positive solvatochromism of BZD a demonstrated the π-π* nature of the singlet excited state. Dual fluorescence was observed in the emission spectra of BZD f and g, while their spectrum in different concentration showed only one peak short wavelength (SW) in dilute solutions. The main peak in SW around 370nm was attributed to the monomer of BZD (f* or g*) and the broader emission shifted to the visible region around 400nm in middle wavelength (MW) to the intermolecular excimer emission of BZD ([f/f]*or [g/g]*). The observed phenomena, such as solvatochromism, dual fluorescence, some red shifts caused by substitution, and larger Stokes shift indicated the existence of intramolecular charge transfer (ICT) in the BZDs series. The phosphorescence emission of the BZDs demonstrated their intersystem crossing (ISC) process.

Synthesis and Biological Evaluation of Thiosemicarbazide Derivatives Endowed with High Activity toward Mycobacterium Bovis.

Thiosemicarbazides are potent intermediates for the synthesis of pharmaceutical and bioactive materials and thus, they are used extensively in the field of medicinal chemistry. The imine bond (-N=CH-) in this compounds are useful in organic synthesis, in particular for the preparation of heterocycles and non-natural ß-aminoacids. In this paper the synthesis of some new thiosemicarbazide derivatives by condensation reaction of various aldehydes or ketones with 4-phenylthiosemicarbazide or thiosemicarbazide is reported. This synthesis method has the advantages of high yields and good bioactivity. The structures of these compounds were confirmed by IR, mass, 1H NMR, 13C NMR, and single-crystal X-ray diffraction studies. All of these compounds were tested for their in-vitro anti-mycobacterial activity. The influence of the functional group and position of substituent on anti-bacterial activity of compounds is investigated too. The preliminary results indicated that all of the tested compounds showed good activity against the test organism. The compounds 11 and 30 showed the highest anti-tubercular activity (0.39 µg/mL). This synthesis method has the advantages of high yields and good bioactivity.