Organic & Biomolecular Chemistry最新文献

One of the pathological manifestations of phenylketonuria (PKU) is the formation of fibrillar assemblies of the aromatic amino acid L-phenylalanine at pathological concentrations. As a possible therapeutic strategy for PKU, we introduce a nanocarbon system passivated with polyphenol gallic acid (CNPGA), which has the ability to disrupt and inhibit the formation of fibrillar assemblies. The CNPGA was prepared using a rapid and facile microwave-assisted one-pot method from an aqueous solution of sucrose and gallic acid and fully characterized using UV-Vis, FT-IR, XRD, XPS, TEM, zeta potential and DLS measurements. The CNPGA-mediated inhibition and disruption of L-phenylalanine fibrils was examined using a thioflavin T (ThT) assay. The change in the conformation of the fibrils upon CNPGA treatment was assessed by means of circular dichroism spectroscopy. Visual analysis of the rupture of fibrillar assemblies was performed using SEM. Finally, the biocompatibility of CNPGA was evaluated in two normal cell lines, HaCaT (human epidermal keratinocyte cell line) and Vero (African green monkey kidney cell line) cells.

In modern synthetic organic chemistry, C-H bond activation has attracted the attention of researchers for various organic transformations, including C-C and C-X (X = N, O, S, and P) bond formation and heterocycle construction. For the purpose of C-C bond formation or annulation, C-H bond functionalization is more advantageous than conventional cross-coupling reactions owing to the non-requirement of pre-functionalized substrates, less waste generation, higher atom economy, low operational cost and direct incorporation of the desired functional group. Earlier, it was considered that transition metals and their coordinating directing groups are crucial for performing C-H activation reactions. Later, the hazardous effect of the metals on the environment and human health introduced metal-free organic reactions in the synthetic chemistry toolbox. Metal-free organic transformations are gradually becoming more preferred by both industry and academia for construction of bioactive molecules considering their advantages such as low operational cost, less number of steps for the synthesis, low risk of metal contamination-associated hazards, and less possibility of error in the results of biological evaluations. For achieving the mentioned advantages, two different sustainable practices (i.e., metal-free approaches and C-H bond activation) were combined into a new approach of sustainable synthesis, entitled "metal-free C-H bond activation approach". Although the C-H bond activation strategy is itself a sustainable approach, one or more sustainable approaches were also incorporated for synergism in the C-H functionalization protocol. In this review, we focus on metal-free C-C bond formation reactions carried out via a C-H activation approach. This review covers metal-free C-H alkylation, alkenylation, arylation, carbonylation, carbamoylation, alkynylation and cyanation reactions with emphasis on their reaction mechanisms.

A palladium-catalyzed cross-coupling methodology has been developed by utilizing aryl alkyl selenides and organoboranes. In this deseleniative process, the organoselenium moiety acts as a pseudohalide, facilitating the cleavage of the C-Se bond through the synergistic action of palladium(0) and stoichiometric copper(I) thiophene-2-carboxylate. When conducted under microwave irradiation, the reaction methodology demonstrates broad substrate compatibility, scalability to gram-scale synthesis, and moderate to good yields. By employing commercially available boronic acids, this approach enhances practicality and potential applications in organic synthesis.

Herein we report copper-catalyzed coupling of alkynyl glycosides facilitating the synthesis of buta-1,3-diyne-linked disaccharides. The reaction is characterized by mild conditions employing eco-friendly reagents, resulting in good yields of the desired products. This methodology exhibits significant functional group tolerance with broad substrate scope. Furthermore, we have successfully extended this approach to the synthesis of buta-1,3-diyne-linked dinucleosides.

Hetero-Diels-Alder reactions of furans and isobenzofurans provide convergent redox-neutral access to hetero-oxanorbornene derivatives. These versatile intermediates serve as precursors to a variety of heterocycles, polymers, and complex natural products. Herein we comprehensively review this area of research and speculate on what developments are required to advance the field.

Functionalization of the quinoline ring has emerged as a transformative strategy in modern synthetic chemistry because of the medicinal potential of quinoline-based scaffolds. The precise and selective introduction of diverse functional groups significantly expands the chemical space and enhances the pharmacological profile of quinoline derivatives. By carefully selecting catalysts, reaction conditions, and directing groups, researchers have unlocked novel pathways for the efficient synthesis of quinoline-based compounds with improved efficacy, target selectivity, and safety. This approach accelerates drug discovery and broadens the therapeutic potential of quinoline scaffolds for treating various diseases, including cancer, infectious diseases, and neurological disorders. Over the past two decades, this field has experienced exponential growth, as evidenced by the increasing number of research publications and comprehensive review articles. This surge in interest is driven by the potential of quinoline functionalization to generate novel drug candidates with enhanced bioactivity and reduced side effects. This review summarizes the key advancements from January 2021 to 2024, focusing on the latest methodologies, catalytic systems, and applications in drug development.

We report a cascade reaction of α-aryl vinyl and propargyl sulfonium salts with C-nucleophiles, resulting in the formation of functionalized benzyl and homoallyl thioethers, respectively, in good yields. In this novel reaction, a vinyl sulfonium derivative undergoes Michael addition with a C-nucleophile followed by [2,3]-sigmatropic rearrangement. This domino reaction is very general and takes place readily under mild conditions.

2,2-Disubstituted indolin-3-ones, which are essential components in many manufactured chemicals, dyes, and naturally occurring bioactive alkaloids, have emerged as exciting synthetic targets. Much attention has been paid to accessing these units, particularly in an asymmetric fashion, during the last decade. In this review article, we discuss the current state of available methods with existing mechanistic pathways for accessing chiral indolin-3-one derivatives under various catalytic systems. This overall presentation of asymmetric catalytic protocols to access 2,2-disubstituted or fused indolin-3-ones with an aza-quaternary centre is categorized based on the reaction modes of 2-substituted-3H-indole-3-one derivatives or other similar protocols.

An efficient method for diastereo-controlled synthesis of (Z)-fluoroalkene dipeptide isosteres (FADIs) was developed. Two chiral centers were constructed by applying our synthetic methodology for chloroalkene dipeptide isosteres (CADIs) using Ellman's imine for corresponding to the N-terminal amino acid residues and Oppolzer's sultam for corresponding to the C-terminal amino acid residues, affording dipeptidomimetic in a stereocontrolled manner with high diastereoselectivity.

HMF (5-hydroxymethylfurfural), a renewable raw material from biomass, was used as the starting material to provide 5-aryl-4-hydroxymethyl-4-hydroxycyclopentenones with functionalized aryl groups. First, arylic substituents were added to the aldehyde moiety of HMF under rhodium- or palladium-catalyzed 1,2-addition of arylboronic acids, in mild conditions to respect the very sensitive HMF reactivity. Subsequently, these non-symmetrical furan-2,5-dicarbinols, through Piancantelli rearrangement, provided the desired cyclopentenones under microwave activation or subcritical water conditions (100 °C and 100 bar) using Zippertex technology, in a regio- and diastereo-selective manner. These synthesized bis-hydroxylated cyclopentenone derivatives exhibited significant antimicrobial activity against Gram-positive bacteria Micrococcus luteus, Bacillus subtilis and Gram-negative bacteria Escherichia coli.