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To [n]Acenes and Beyond!
摘要： The Domino Hexadehydro-Diels–Alder Reaction Transforms Polyynes to Benzynes to Naphthynes to Anthracynes to Tetracynes (and Beyond?)
关键词： domino reaction,benzynes,Diels–Alder cycloaddition
更新于2025-09-23 15:23:52
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Enamine–azide [2+3]-cycloaddition as a method to introduce functional groups into fluorescent dyes
摘要： Fluorescent dyes are a significant research tool with various applications in modern science. However, many experiments require the preparation of covalent dye conjugates, which is impossible without the presence of a functional group on the dye molecule. Unfortunately, the introduction of such groups is often a complicated task. Herein, we report a novel approach for the introduction of functional groups into fluorescent dyes, based on the [2+3]-cycloaddition reaction of 'terminal' enamines with azides. The synthesis of such 'terminal' enamines is carried out by the condensation of formamide acetals with a methyl group that is influenced by a strong electron withdrawing group. Thus, the proposed functionalization technique requires only the presence of a methyl group in the relevant position of the initial non-functionalized fluorescent dye.
关键词： Enamine,Azide,Cycloaddition,Fluorophore
更新于2025-09-23 15:22:29
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Synthesis and Characterization of a Pentiptycene-Derived Dual Oligoparaphenylene Nanohoop
摘要： Structural designs by combining the oligoparaphenylene-derived nanohoops with other functional organic building blocks should lead to novel molecular architectures with intriguing properties. Herein, the synthesis of a pentiptycene-derived chiral dual nanohoop molecule has been achieved with key steps including ring expansion and transannular [4+2] cycloaddition across a 64-membered macrocycle. The crystal structure of the nanohoop molecule displays ordered packing pattern with long-range channels in the solid-state. In addition, non-racemizable enantiomers of the nanohoop have been obtained through resolution, exhibiting promising chiroptical properties.
关键词： Diels-Alder cycloaddition,oligoparaphenylene,nanohoop,macrocycle,pentiptycene
更新于2025-09-23 15:22:29
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Synthesis of low surface-energy polyepichlorohydrin triazoles thin film
摘要： In this investigation, a new polymer with low surface energy was synthesized by grafting a triazole group onto polyepichlorohydrin (PECH) rubber that contained no halogens. The chlorine on PECH was first replaced by an azide group, and this attached azide was then converted to a triazole group with alkyl chains using the azide-alkyne Huisgen cycloaddition reaction. Analyses confirmed the structure of final product, PECH-triazole polymer. The grafting reactions increased the surface roughness. The static contact angles of water or CH2I2 droplets on the PECH-azole film were 101.7° and 71.3°, respectively. The advancing and receding contact angles for water on PECH-azide were 119.8° and 13.7°, respectively. The PECH-triazole polymer has omniphobic properties with rose petal characteristics. The PECH-triazole has low dispersive surface energy (21 mN/m) and negligible non-dispersive surface energy, giving a wetting envelope that is similar to the one of PTFE polymer. X-ray photoelectron spectroscopy and transmission infrared spectroscopy suggested that the interactions of the N atoms on the triazole ring and the O atoms on the PECH backbone constrained the orientation of CH2 groups and reduced the surface energy of the thin film.
关键词： Azide-alkyne Huisgen cycloaddition,Polyepichlorohydrin,Low surface free energy,High water adhesion,Triazole
更新于2025-09-23 15:22:29
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Supramolecular Control of Photocycloaddition in Solution: In Situ Stereoselective Synthesis and Release of Cyclobutanes
摘要： A new class of supramolecular metallacycles capable of undergoing photochemical reactions and in situ release of cyclobutanes in solution is described. The molecular metallacycles were generated by employing dinuclear metal-carbene complexes as organometallic clips and olefin-functionalized bridging ligands through coordination-driven self-assembly. Photolysis of these molecular metallacycles in situ led to structural interconversion and release of the formed cyclobutane products with quantitative conversion. Further modifications at the obtained cyclobutanes provided a series of new species containing the cyclobutane skeleton.
关键词： template,photochemical [2+2] cycloaddition,carbenes,cyclobutane,organometallic metallacycle
更新于2025-09-23 15:22:29
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Supramolecular Control of Photocycloaddition in Solution: In Situ Stereoselective Synthesis and Release of Cyclobutanes
摘要： A new class of supramolecular metallacycles capable of undergoing photochemical reactions and in situ release of cyclobutanes in solution is described. The molecular metallacycles were generated by employing dinuclear metal-carbene complexes as organometallic clips and olefin-functionalized bridging ligands through coordination-driven self-assembly. Photolysis of these molecular metallacycles in situ led to structural interconversion and release of the formed cyclobutane products with quantitative conversion. Further modifications at the obtained cyclobutanes provided a series of new species containing the cyclobutane skeleton.
关键词： template,photochemical [2+2] cycloaddition,carbenes,cyclobutane,organometallic metallacycle
更新于2025-09-23 15:22:29
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A Preferential Photoreaction in a Porous Crystal, Metal-Macrocycle Framework (MMF): Pd <sup>II</sup> -Mediated Olefin Migration over [2+2] Cycloaddition
摘要： A nano-sized confined space with well-defined functional surfaces has great potential to control the efficiency and selectivity of catalytic reactions. Herein we report that a 1,6-diene, which normally forms an intramolecular [2+2] cycloadduct under photo-irradiation, preferentially undergoes a photo-induced olefin migration in a porous crystal, metal–macrocycle framework (MMF), and alternatively [2+2] cycloaddition is completely inhibited in the confined space. A plausible reaction mechanism for olefin migration triggered by the photo-induced dissociation of the Pd-Cl bond is suggested based on UV-vis diffuse reflectance spectroscopy, single-crystal XRD, and MS-CASPT2 calculation. The substrate scope of the photo-induced olefin migration in MMF was also examined using substituted allylbenzene derivatives.
关键词： photo-induced olefin migration,metal–macrocycle framework,Pd-Cl bond dissociation,nano-sized confined space,[2+2] cycloaddition
更新于2025-09-23 15:21:21
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Harnessing sun for catalyst and sensitizer free regio- and stereo-selective [2+2] cycloaddition
摘要： Presence of cyclobutane rings in bioactive natural products makes them a popular synthetic target. Most common strategy for synthesizing cyclobutanes is [2+2] cycloaddition, which is usually facilitated by using ultraviolet radiation and catalysts. Herein we report the design and synthesis of densely functionalized cyclobutanes by alleviating these drawbacks and using sunlight. Further, we identified the putative mechanism of the transformation based on kinetic, fluorescence and crystallographic studies and evaluated biological activities of the products against MCF7 cell lines. The rational design of the olefinic substrates was based on their UV-vis spectra. The generic aspect of the reaction was elucidated by the syntheses of diverse analogs of cyclobutanes. Further, crystal structures and UV-vis spectra of the olefinic partners assisted us in rationalizing the stereoselectivity of the heterodimers. We believe this energy-efficient mild approach will provide a substantial contribution to the existing repertoire of strategies to regio- and stereoselectively access cyclobutanes.
关键词： Cycloaddition,Photocatalysis,Photodimerization,Self-sensitizer,Regio-selectivity
更新于2025-09-23 15:21:01
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Modular medical imaging agents based on azidea??alkyne Huisgen cycloadditions: Synthesis and prea??clinical evaluation of 18Fa??labeled PSMAa??tracers for prostate cancer imaging.
摘要： The seminal contribution of Rolf Huisgen to develop the [3+2]-cycloaddition of 1,3-dipolar compounds, its azide-alkyne variant has established itself as the key step in numerous organic syntheses and bioorthogonal processes in materials science and chemical biology. In the present study, the copper(I)-catalyzed azide-alkyne cycloaddition was applied for the development of a modular molecular platform for medical imaging of the prostate specific membrane antigen (PSMA), using positron emission tomography. This process is shown from molecular design, through synthesis automation and in vitro studies, all the way to preclinical in vivo evaluation of fluorine-18– labeled PSMA-targeting ‘F-PSMA-MIC’ radiotracers (t? = 109.7 min). Preclinical data indicate that the modular PSMA-scaffold has similar binding affinity and imaging properties to the clinically used [68Ga]PSMA-11. Furthermore, we demonstrated that targeting the arene-binding in PSMA, facilitated through the [3+2]-cycloaddition, can improve binding affinity, which was rationalized by molecular modeling. The here presented PSMA-binding scaffold potentially facilitates easy coupling to other medical imaging moieties, enabling future developments of new modular imaging agents.
关键词： prostate specific membrane antigen,positron emission tomography,fluorine-18,azide-alkyne Huisgen cycloaddition,modular imaging agents
更新于2025-09-23 15:19:57
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Automated generation of photochemical reaction data by transient flow experiments coupled with online HPLC analysis
摘要： The automated generation and acquisition of large-scale reaction data is crucial to recent progress in organic synthesis and pharmaceutical process development. To follow reaction progress over time, time-series of reaction data can be generated by transient flow experiments, which allow to investigate reactions in a short transient period between two steady-state operations of a continuous-flow microreactor. The acquisition of analytical data in this short transient period, however, remains challenging since separation techniques like HPLC – though able to cope with highly complex samples – are typically regarded as too slow for the required acquisition rates. We break the longstanding coupling between the timescale of the continuous-flow experiment and the acquisition rate of the analytical method with the introduction of the multiple heart-cutting interface, which allows for sample parking prior to sample analysis. Transient flow experiments are presented for the [2+2] cycloaddition between 1-methyl-2-quinolinone and coumarin. Competing homo- and crossdimerization reactions are quantitatively investigated in systematic reaction parameter screenings with more than 400 data points. Results provide precious insights into this complex photochemical system – not only for reaction optimization, but also for a more profound understanding of the involved chemical processes.
关键词： quinolinone,online HPLC analysis,photochemical reaction data,homo- and crossdimerization reactions,[2+2] cycloaddition,coumarin,automated generation,transient flow experiments
更新于2025-09-23 15:19:57