Rh(iii)-catalyzed synthesis of dibenzo[b,d]pyran-6-ones from aryl ketone O-acetyl oximes and quinones via C-H activation and C-C bond cleavage

The Versatile and Strategic O-Carbamate Directed Metalation Group in the Synthesis of Aromatic Molecules: An Update

The aryl O-carbamate (ArOAm) group is among the strongest of the directed metalation groups (DMGs) in directed ortho metalation (DoM) chemistry, especially in the form Ar-OCONEt2. Since the last comprehensive review of metalation chemistry involving ArOAms (published more than 30 years ago), the field has expanded significantly. For example, it now encompasses new substrates, solvent systems, and metalating agents, while conditions have been developed enabling metalation of ArOAm to be conducted in a green and sustainable manner. The ArOAm group has also proven to be effective in the anionic ortho-Fries (AoF) rearrangement, Directed remote metalation (DreM), iterative DoM sequences, and DoM-halogen dance (HalD) synthetic strategies and has been transformed into a diverse range of functionalities and coupled with various groups through a range of cross-coupling (CC) strategies. Of ultimate value, the ArOAm group has demonstrated utility in the synthesis of a diverse range of bioactive and polycyclic aromatic compounds for various applications.

Oxime Esters: Flexible Building Blocks for Heterocycle Formation

Oxime esters as the applicable building blocks, internal oxidizing agents, and directing groups in the synthesis of -, S-, and O-containing heterocycle scaffolds have gained great attention in the last decade. This review provides an overview of recent advances in the cyclization of oxime esters with various functional group reagents under transition metal and transition metal-free catalyzed conditions. Moreover, the mechanistic aspects of these protocols are explained in detail.

Synthesis and characterization of an Fe-MOF@Fe3O4 nanocatalyst and its application as an organic nanocatalyst for one-pot synthesis of dihydropyrano[2,3-c]chromenes

In this study, the recyclable heterogeneous cluster bud Fe-MOF@Fe₃O₄ 'nanoflower' composite (CB Fe-MOF@Fe₃O₄ NFC) was successfully synthesized using Fe(NO₃)₃·9H₂O, 8-hydroxyquinoline sulfate monohydrate, and Fe₃O₄ nanoparticles by microwave irradiation. The as-prepared CB Fe-MOF@Fe₃O₄ NFC was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), vibrational sampling magnetometry (VSM), and Fourier transform infrared spectroscopy (FTIR). The CB Fe-MOF@Fe₃O₄ NFC samples proved to have excellent catalytic activity. The activity of the CB Fe-MOF@Fe₃O₄ NFC nanocatalyst was explored in the synthesis of dihydropyrano[3, 2-c]chromene derivatives via a three-component reaction of 4-hydroxycoumarin, malononitrile, and a wide range of aromatic aldehyde compounds. Optimized reaction conditions had several advantages, including the use of water as a green solvent, environmental compatibility, simple work-up, reusability of the catalyst, low catalyst loading, faster reaction time, and higher yields.

Application of sulfur-coated magnetic carbon nanotubes for extraction of some polycyclic aromatic hydrocarbons from water resources

In the present work, novel sulfur-coated magnetic carbon nanotubes (MCNTs-S) material was fabricated by S coating on the MCNTs using a simple heating procedure. TGA, EDX, XRD, TEM, and VSM were employed to characterize the as-prepared composite. Using HPLC-UV system, the produced superparamagnetic sorbent was employed for the extraction and measurement of trace levels of five polycyclic aromatic hydrocarbons (PAHs) in environmental waters. The synergistic effect of the sulfur layer and CNTs substrate is primarily responsible for the remarkable extraction efficiency of the MCNTs-S sorbent towards PAHs. The experimental factors including MCNTs-S dosage, sorption time, elution solvent, ionic strength and solution pH were explored and optimized. Considering that the ionic strength and pH do not have any impact on the PAHs extraction, as a result, there is no need the unnecessary adjustment of the water samples. The linear dynamic ranges and detection limits under optimal conditions were in the range of 0.05-0.11 ng mL^-1 and 0.2-150 ng mL^-1, respectively. The analysis of PAHs in the real samples (sea water and river water) using this approach was successfully assessed with appropriate recovery values (94.6%-99.0%).

Molecular Characterization of an Isoflavone 2'-Hydroxylase Gene Revealed Positive Insights into Flavonoid Accumulation and Abiotic Stress Tolerance in Safflower

Flavonoids with significant therapeutic properties play an essential role in plant growth, development, and adaptation to various environments. The biosynthetic pathway of flavonoids has long been studied in plants; however, its regulatory mechanism in safflower largely remains unclear. Here, we carried out comprehensive genome-wide identification and functional characterization of a putative cytochrome P45081E8 gene encoding an isoflavone 2'-hydroxylase from safflower. A total of 15 CtCYP81E genes were identified from the safflower genome. Phylogenetic classification and conserved topology of CtCYP81E gene structures, protein motifs, and cis-elements elucidated crucial insights into plant growth, development, and stress responses. The diverse expression pattern of CtCYP81E genes in four different flowering stages suggested important clues into the regulation of secondary metabolites. Similarly, the variable expression of CtCYP81E8 during multiple flowering stages further highlighted a strong relationship with metabolite accumulation. Furthermore, the orchestrated link between transcriptional regulation of CtCYP81E8 and flavonoid accumulation was further validated in the yellow- and red-type safflower. The spatiotemporal expression of CtCYP81E8 under methyl jasmonate, polyethylene glycol, light, and dark conditions further highlighted its likely significance in abiotic stress adaption. Moreover, the over-expressed transgenic Arabidopsis lines showed enhanced transcript abundance in OE-13 line with approximately eight-fold increased expression. The upregulation of AtCHS, AtF3'H, and AtDFR genes and the detection of several types of flavonoids in the OE-13 transgenic line also provides crucial insights into the potential role of CtCYP81E8 during flavonoid accumulation. Together, our findings shed light on the fundamental role of CtCYP81E8 encoding a putative isoflavone 2'-hydroxylase via constitutive expression during flavonoid biosynthesis.

Fluorescent and Phosphorescent Nitrogen-Containing Heterocycles and Crown Ethers: Biological and Pharmaceutical Applications

Fluorescent molecules absorb photons of specific wavelengths and emit a longer wavelength photon within nanoseconds. Recently, fluorescent materials have been widely used in the life and material sciences. Fluorescently labelled heterocyclic compounds are useful in bioanalytical applications, including in vivo imaging, high throughput screening, diagnostics, and light-emitting diodes. These compounds have various therapeutic properties, including antifungal, antitumor, antimalarial, anti-inflammatory, and analgesic activities. Different neutral fluorescent markers containing nitrogen heterocycles (quinolones, azafluoranthenes, pyrazoloquinolines, etc.) have several electrochemical, biological, and nonlinear optic applications. Photodynamic therapy (PDT), which destroys tumors and keeps normal tissues safe, works in the presence of molecular oxygen with light and a photosensitizing drugs (dye) to obtain a therapeutic effect. These compounds can potentially be effective templates for producing devices used in biological research. Blending crown compounds with fluorescent residues to create sensors has been frequently investigated. Florescent heterocyclic compounds (crown ether) increase metal solubility in non-aqueous fluids, broadening the application window. Fluorescent supramolecular polymers have widespread use in fluorescent materials, fluorescence probing, data storage, bio-imaging, drug administration, reproduction, biocatalysis, and cancer treatment. The employment of fluorophores, including organic chromophores and crown ethers, which have high selectivity, sensitivity, and stability constants, opens up new avenues for research. Fluorescent organic compounds are gaining importance in the biological world daily because of their diverse functionality with remarkable structural features and positive properties in the fields of medicine, photochemistry, and spectroscopy.

Direct selenosulfonylation of unsaturated compounds: a review

In this review, we have discussed recent developments on the direct selenosulfonylation of unsaturated compounds which lead to the formation of two new carbon-sulfur and carbon-selenium bonds in a single operation. The reactions were classified based on the type of starting unsaturated compound and product. Thus, the review is divided into three major sections. The first describes the current literature on selenosulfonylation of alkenes. The second section covers the available literature on selenosulfonylation of alkynes. The third focuses exclusively on selenosulfonylation of allenes.

In this review, we have discussed recent developments on the direct selenosulfonylation of unsaturated compounds which lead to the formation of two new carbon-sulfur and carbon-selenium bonds in a single operation.