Beilstein Journal of Organic Chemistry最新文献

The review is devoted to strategies for contraction of six-membered cycles in the synthesis of functionalized cyclopentane/enones, which are biologically active compounds. The main synthetic methods of ring contraction (ozonolysis-aldol condensation, ozonolysis-Dieckmann reaction, Baeyer-Villiger cleavage-Dieckmann reaction) and rearrangements (benzil, semipinacol, with the participation of thallium- and iodine-based oxidants, photochemical, Wolff, Meinwald, Wagner-Meerwein and Favorskii) are presented. The review summarizes literature data covering the last 12 years, with some exceptions of earlier works due to the importance of the published information.

In the present study, 21 fused isoxazolidines were synthesized in yields ranging from good to excellent. Methyl laurate was identified as the easily accessible optimal solvent medium for the reaction, and the related compounds were obtained through straightforward isolation techniques in a relatively short time frame (5-80 minutes). A comprehensive investigation was conducted utilizing various web platforms, encompassing ecological and environmental risk assessments, toxicity, pesticide similarity, and biodegradability of methyl laurate in comparison with a series of conventional organic solvents, water, some fatty acids and their derivatives. The findings of this investigation revealed that methyl laurate exhibited better green solvent properties when evaluated against other solvents.

A synthetic strategy for the preparation of spiro[indoline-3,2'-pyrrolidine] derivatives has been developed, featuring a two-step sequence consisting of the reaction of 2-arylindoles with α,β-unsaturated ketones, followed by Fe(II)-catalyzed spirocyclization of readily accessible oxime acetates. The method exhibits a broad substrate scope and good functional group tolerance. The synthesized spirocyclic compounds showed no significant antimicrobial activity.

A synthetic study toward vibralactone, a potent inhibitor of pancreatic lipase, is reported. The synthesis of the challenging all-carbon quaternary center within the cyclopentene ring was achieved through intramolecular alkylidene carbene C-H insertion.

To our knowledge, this work represents one of the earliest comparative studies on the anion-binding behaviors of carbazole-based structural analogs, demonstrating that a flexible macrocycle markedly improves iodide binding affinity via an induced-fit mechanism. The flexible analog PBG exhibits a 22.78-fold higher fluorescence quenching efficiency upon iodide binding compared to the rigid WDG (K _PBG /K _WDG = 22.78), demonstrating its potential as a highly sensitive optical probe and offering a novel strategy for engineering dynamic supramolecular receptors. Two carbazole-based macrocyclic probes, PBG (flexible benzene ring) and WDG (rigid fluorene backbone), were synthesized via Friedel-Crafts reactions. Their iodide (I^-) recognition properties were systematically explored using ¹H NMR, UV-vis absorption, and fluorescence spectroscopy. Quantitative analysis via the Benesi-Hildebrand equation and nonlinear fitting demonstrated that flexible PBG achieves superior I^- binding (K _PBG = 1.387 × 10⁵ M^-1) through induced-fit conformational adjustments, whereas rigid WDG (K _WDG = 6.089 × 10³ M^-1) is constrained by preorganized cavity geometry, adhering to a conformational selection mechanism. This work elucidates the synergistic interplay between conformational dynamics and localized structural adaptations governing anion recognition. The findings advance the rational design of tunable, high-affinity anion receptors and deepen the understanding of conformational regulation in supramolecular systems.

Integrating molecular photoswitches into rotaxanes offers unique opportunities for precise control over their structural, dynamic, and functional properties. By harnessing light as a non-invasive stimulus with high spatial and temporal resolution, these photoswitches allow for the modulation of the rotaxanes' intra- and intermolecular interactions, optoelectronic properties, and shuttling dynamics. In this review, we discuss key examples of photoswitchable rotaxanes, organized according to the position of the photoswitch, either embedded in the axle or incorporated into the macrocycle. We examine the major classes of photoswitches used, including their switching mechanisms and the resulting influence on rotaxane operation. Due to their architectural versatility and precise light control, photoswitchable rotaxanes hold promise for a broad range of applications, including light-responsive molecular machines, smart materials, and biofunctional systems. However, emerging applications increasingly require rethinking and developing new structural designs that incorporate more efficient and advanced photoswitches to fully realize their potential.

In recent years, the Norrish-Yang cyclization and related photoredox reactions of dicarbonyls have been extensively utilized in natural product synthesis. This review summarizes the latest advancements in these reactions for constructing terpenoids, alkaloids, and antibiotics. Through Norrish-Yang cyclization, dicarbonyls (e.g., 1,2-diketones and α-keto amides) can efficiently construct sterically hindered ring structures, which can further undergo ring-opening or rearrangement reaction to assemble complex molecular frameworks. Additionally, quinone photoredox reactions involving single-electron transfer (SET) processes provide novel strategies for the stereoselective synthesis of useful structures such as spiroketals. This review, drawing on examples from recently reported natural product syntheses, elaborates on reaction mechanisms, factors governing regioselectivity and stereoselectivity, and the impact of substrate structures on reaction pathways. These reactions not only serve as robust tools for the streamlined synthesis of natural products but also establish a solid foundation for subsequent pharmaceutical investigations.

In this review, we summarize and compare four total syntheses of complanadine A, a complex and pseudo-dimeric lycopodium alkaloid with promising neurotrophic activity and potential for pain management. These four total syntheses are from the groups of Siegel, Sarpong, Tsukano, and Dai. Each of the four total syntheses contains innovative strategies and creative tactics, reflecting how emerging synthetic capabilities and concepts can positively impact natural product total synthesis.

Contamination of water bodies by micropollutants including industrial dyes is a worldwide health and environmental concern. We report the design, synthesis, and characterization of a series of methylene-bridged glycoluril dimers G2W1-G2W4 that are insoluble in water and that differ in the nature of their aromatic sidewalls (G2W4: benzene, G2W3: naphthalene, G2W1 and G2W2: triphenylene). We tested G2W1-G2W4 along with comparator H2 as solid-state sequestrants for a panel of five dyes (methylene blue, methylene violet, acridine orange, rhodamine 6G, and methyl violet 6B). We find that catechol-walled H2 (OH substituents) is a superior sequestrant compared to G2W1-G2W4 (OMe substituents). X-ray crystal structures for G2W1 and G2W3 suggest that the OMe groups fill their own cavity and thereby decrease their abilities as sequestrants. H2 achieved a removal efficiency of 94% for methylene blue whereas G2W1 demonstrated a 64% removal efficiency for methylene violet; both sequestration processes were largely complete within 10 minutes.