Organic & Biomolecular Chemistry最新文献

The multi-component ring-opening reactions of cyclic ethers offer an efficient strategy for the rapid introduction of multiple functional groups and the construction of complex molecular architectures. Despite the minimal ring strain in five- and six-membered rings presenting a significant challenge for ring-opening, advancements have been made. Traditional acid-catalyzed pathways have been complemented by a novel approach involving carbene-induced oxonium intermediate formation, which has emerged in recent years and expanded the selectivity of ring-opening reactions. This review outlines the evolution of carbene-induced ring-opening reactions of cyclic ethers over the past two decades, focusing on the development of carbene precursors and the pathways of carbene formation. The insights provided are anticipated to inform and inspire the creation of new carbene sources and the advancement of oxonium intermediates, thereby contributing to the field's progress.

Under mild visible light conditions, formates facilitate C-O cleavage via the EDA complex and SCS strategy, yielding α-carbonyl alkyl radicals. These radicals then react with olefins under air conditions, leading to the synthesis of diaryl 1,4-dicarbonyl compounds. Mechanistic studies reveal that α-formyloxy ketone is generated in situ by the reaction between α-brominated acetophenone and formates, followed by the formation of the EDA complex. Additionally, formates also serve as a single-electron reducing reagent in the reaction.

A highly practical and efficient Cp*Co(III)-catalyzed C-H alkylation/alkenylation reaction of anilides with maleimides and acrylates was developed, during which a weakly coordinating amide carbonyl group functioned as the directing group. This approach features high efficiency, good functional group tolerance, and broad substrate scope, and a variety of 3-substituted succinimides and ortho-alkenylated anilides were synthesized in moderate to excellent yields. Furthermore, the reaction is highly selective, affording mono-ortho-alkylated/alkenylated products only. In addition, synthetic transformations of the 3-substituted succinimide products demonstrate the practicability of the reaction.

Bacterial biofilms are surface-attached communities consisting of non-replicating persister cells encased within an extracellular matrix of biomolecules. Unlike bacteria that have acquired resistance to antibiotics, persister cells enable biofilms to demonstrate innate tolerance toward all classes of conventional antibiotic therapies. It is estimated that 50-80% of bacterial infections are biofilm associated, which is considered the underlying cause of chronic and recurring infections. Herein, we report a modular three-step synthetic route to new halogenated phenazine (HP) analogues from diverse aniline and nitroarene building blocks. The HPs were evaluated for antibacterial and biofilm-killing properties against a panel of lab strains and multidrug-resistant clinical isolates. Several HPs demonstrated potent antibacterial (MIC ≤ 0.39 μM) and biofilm-eradicating activities (MBEC < 10 μM) with 6,8-ditrifluoromethyl-HP 15 demonstrated remarkable biofilm-killing potencies (MBEC = 0.15-1.17 μM) against Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus clinical isolates. Confocal microscopy showed HP 15 induced significant losses in the polysaccharide matrix in MRSA biofilms. In addition, HP 15 showed increased antibacterial activities against dormant Mycobacterium tuberculosis (Mtb, MIC = 1.35 μM) when compared to replicating Mtb (MIC = 3.69 μM). Overall, this new modular route has enabled rapid access to an interesting series of potent halogenated phenazine analogues to explore their unique antibacterial and biofilm-killing properties.

A porphyrin comprising a carboxyl-functionalized pyridine moiety was synthesized and characterized using ¹H NMR, ¹³C NMR, FT-IR, powder-XRD, BET, ICP-MS, SEM and EDAX. The proton level (H₀ = 1.19) and energy band gap (1.39 eV) were determined via UV-Vis spectrophotometry. The UV-visible and fluorescence emission spectra indicated the absorption window of the porphyrin photocatalyst with a distinct Soret band at 424 nm and four Q-bands at 517, 558, 595, and 649 nm. The existence of four Q-bands, the powder XRD data and the ICP-MS analysis supported the absence of metal in the porphyrin photocatalyst. The best photocatalytic conditions generated using Box–Behnken design of RSM (0.2 mol% PcCFP, 5 W LED, 1 : 1.2 ArX : ArCONH₂, 24 h) were confirmed through the model reaction of benzamide and 1-bromo-4-nitrobenzene. The N-arylation of benzamide was achieved in a custom-built photoreactor at ambient conditions under exposure to 5 W LED light. Different ArX compounds comprising electron-repelling and electron-attracting groups were assessed to test the potential of the photocatalyst. The porphyrin was found to exhibit significant catalytic activity for C–N bond formation, resulting in 21–73% yields of the substituted benzanilide products. The N-arylated benzamide formation was confirmed using ¹H NMR, ¹³C NMR, HR-MS and SC-XRD. Additionally, heteroaryl halides such as 2-bromo-, 3-bromo-, and 4-bromo-pyridine, as well as 2-chloro-4-methylpyridine, were also found to be compatible and provided admirable yields (28–67%). The stability and heterogeneous nature of the porphyrin photocatalyst were confirmed using FT-IR. The stability of the photocatalyst after the sixth run was demonstrated by the slight decline in the yield of the product from 71 to 67%. The formation of an aryl radical was detected using the scavenger TEMPO, which led to the achievement of N-arylated benzamides containing intermediates of industrial drugs.

Synthesis of chemically diverse heterocyclic scaffolds in DNA-encoded libraries is highly demanded. We herein reported a convenient one-pot multi-component on-DNA synthetic strategy to afford multi-substituted 2,3-dihydrofuran scaffolds via pyridinium ylide-mediated cyclization. This reaction exhibited modest to excellent conversions for a broad range of DNA-conjugated aldehydes, β-ketonitriles and pyridinium salts under mild reaction conditions. Furthermore, the compatibility of this strategy with DEL construction was verified by enzymatic DNA ligation, PCR amplification and mock library synthesis.

Retraction of ‘Thiourea dioxide promoted efficient organocatalytic one-pot synthesis of a library of novel heterocyclic compounds’ by Sanny Verma et al., Org. Biomol. Chem., 2011, 9, 6943–6948, https://doi.org/10.1039/C1OB05818E.

A 6-step gram-scale synthesis of the fungal polyketide (±)-gregatin A is described. The synthetic route features an intermolecular 1,3-dipolar cycloaddition, a Mo-mediated disconnection of the isoxazole skeleton, and an acid-mediated deprotection/enamine hydrolysis and hemiketalization cascade.

Correction for ‘A novel platinum(II) complex with a berberine derivative as a potential antitumor agent targeting G-quadruplex DNA’ by Shu-Lin Zhang et al., Org. Biomol. Chem., 2025, https://doi.org/10.1039/d4ob01705f.