Tung oil is commonly utilized for coating protection in wooden products, often attracting attention for its appearance, antimicrobial capabilities, and insect-resistant coatings. However, its poor ...mechanical properties and poor weather resistance stem from excessive self-crosslinking of surplus conjugated double bonds and molecular chains, resulting in poor film wrinkling. Therefore, this study introduces natural rubber via the Diels-Alder reaction to consume the residual double bonds in tung oil, resulting in tung oil/natural rubber composite coatings (NRTO) with excellent mechanical properties and weather resistance. The results indicate that NRTO exhibits excellent mechanical properties, including high elongation (32 %) and strong adhesion (4.55 MPa). Furthermore, NRTO demonstrates outstanding acid resistance and UV aging resistance. Given its many benefits, NRTO film emerges as a promising candidate for substantially protecting wood surfaces in demanding environments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
The enantioselective aza‐Diels–Alder reaction is efficient for constructing chiral tetrahydropyridines, but the catalytic asymmetric aza‐Diels–Alder reaction of ketimines with unactivated dienes is ...still a challenging topic. Herein, guided by computational screening, a highly enantioselective aza‐Diels–Alder reaction of 2‐aryl‐3H‐indol‐3‐ones with unactivated dienes was realized by using a B(C6F5)3/chiral phosphoric acid catalyst system under mild conditions. The reaction has a broad scope with respect to both aza‐Diels–Alder reaction partners and hence offers rapid access to an array of tetrahydropyridine derivatives with pretty outcomes (up to 99 % yield, >20:1 dr and 98:2 er). The reaction is very efficient: lowering catalyst loadings for the model reaction to 0.1 mol %, enantioselectivity is still maintained. The synthetic utility was confirmed by transformations of the products. DFT calculations provide convincing evidence for the interpretation of stereoselection.
Guided by computational screening, a highly enantioselective aza‐Diels–Alder reaction of 2‐aryl‐3H‐indol‐3‐ones with unactivated dienes was realized by using a B(C6F5)3/chiral phosphoric acid catalyst system under mild conditions. The reaction has a broad scope with respect to both aza‐Diels–Alder reaction partners and offers rapid access to an array of tetrahydropyridine derivatives (up to 99 % yield, >20:1 dr and 98:2 er).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Click and drug: A combination of orthogonal click reactions is employed for the preparation of functional iron oxide nanoparticles (IONPs) that show unprecedented hyperthermia‐induced drug release ...through a magnetically stimulated retro‐Diels–Alder (rDA) process. Magnetic stimulation induces sufficient local energy in close proximity to the cycloadduct to initiate the rDA process.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Herein, we pioneer a wavelength‐gated synthesis route to phenalene diimides. Consecutive Diels–Alder reactions of methylisophthalaldehydes and maleimides afford hexahydro‐phenalene‐1,6‐diol diimides ...via 5‐formyl‐hexahydro‐benzofisoindoles as the intermediate. Both photoreactions are efficient (82–99 % yield) and exhibit excellent diastereoselectivity (62–98 % d.r.). The wavelength‐gated nature of the stepwise reaction enables the modular construction of phenalene diimide scaffolds by choice of substrate and wavelength. Importantly, this synthetic methodology opens a facile avenue to a new class of persistent phenalenyl diimide neutral radicals, constituting a versatile route to spin‐active molecules.
Methylisophthalaldehydes form two highly reactive ortho‐quinodimethane dienophiles in a step‐wise and wavelength gated fashion. Trapping with maleimides proceeds with high stereoselectivity under the formation of phenalene diimide scaffolds. Subsequent elimination and oxidation affords a new class of persistent phenalenyl diimide neutral radicals.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Targeted delivery and specific activation of photosensitizers can greatly improve the treatment outcome of photodynamic therapy. To this end, we report herein a novel dual receptor‐mediated ...bioorthogonal activation approach to enhance the tumor specificity of the photodynamic action. It involves the targeted delivery of a biotinylated boron dipyrromethene (BODIPY)‐based photosensitizer, which is quenched in the native form by the attached 1,2,4,5‐tetrazine unit, and an epidermal growth factor receptor (EGFR)‐targeting cyclic peptide conjugated with a bicycle6.1.0non‐4‐yne moiety. Only for cancer cells that overexpress both the biotin receptor and EGFR, the two components can be internalized preferentially where they undergo an inverse electron‐demand Diels–Alder reaction, leading to restoration of the photodynamic activity of the BODIPY core. By using a range of cell lines with different expression levels of these two receptors, we have demonstrated that this stepwise “deliver‐and‐click” approach can confine the photodynamic action on a specific type of cancer cells.
The internalization of two bioorthogonal components mediated by the corresponding receptors, followed by inverse electron‐demand Diels–Alder reaction leads to specific activation of the photodynamic action inside the target cells. This dual receptor‐mediated bioorthogonal activation approach works as an AND logic device that can greatly enhance the precision of antitumoral photodynamic therapy.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Pd‐mediated cysteine allylation allows to constrain and rigidify peptides by linking two cysteine side chains with a large set of easily available stapling reagents. The staple itself can be further ...functionalized based on its inherent reactivity thereby allowing construction of a large variety of solid peptides. More information can be found in the Research Article by C. F. W. Becker et al.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Polymer, heal thyself! Dynamic polymers formed by a reversible Diels–Alder reaction were formed and studied by using neutron scattering at room temperature. They were used to obtain thin films that ...displayed self‐healing at room temperature (see figure).
Dynamers based on reversible Diels–Alder chemistry have been obtained and shown to undergo dynamic exchange at room temperature. Their study in solution by small‐angle neutron scattering indicated the formation of long and highly flexible chains. Polydispersed molecules gave Tg values below room temperature, permitting the generation of a dynamic elastomer upon introduction of a dynamic cross‐linking agent. The use of a system with a low equilibrium constant gives access to materials with interesting self‐healing properties.
Des dynamères basés sur la chimie de Diels–Alder dynamique ont été obtenus et il a pu être montré qu′ils subissaient des échanges dynamiques à température ambiante. Leur étude par diffusion de neutron a montré la formation de chaînes longues et flexibles. La Tg inférieure à la température ambiante obtenue grâce à l′emploi de molécules polydispersées a permis la formation d′un élastomère dynamique, suite à l′introduction d′un agent de réticulation dynamique. Enfin, l′utilisation d′un système ayant une faible constante d′équilibre a permis d′obtenir un matériel avec des propriétés d′autoréparation intéressantes.
Polymer, heal thyself! Dynamic polymers formed by a reversible Diels–Alder reaction were formed and studied by using neutron scattering at room temperature. They were used to obtain thin films that displayed self‐healing at room temperature (see figure).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A remote cascade asymmetric inverse‐electron‐demand oxa‐Diels‐Alder reaction of allyl ketones with isatin‐derived β,γ‐unsaturated α‐keto esters has been developed in the presence of a chiral ...bifunctional squaramide catalyst. Taking advantage of the secondary amide activating group, a series of enantioenriched 3,4’‐pyranyl spirooxindole derivatives bearing three contiguous chiral centers were attained in high yields (84 to >99%) with excellent enantioselectivities (96–99% ee). Moreover, the gram‐scale synthesis and the construction of 1‐benzazepine scaffold by the product were also demonstrated.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Arylhydroxylamines were used in the nitroso‐Diels–Alder reaction to generate in situ nitrosoarenes under visible‐light, catalytic and aerobic conditions. Mixing a solution of aryl‐ or ...heteroarylhydroxylamines with conjuguated dienes in the presence of a catalytic amount of Ru(bpy)3Cl2 afforded 3,6‐dihydro‐1,2‐oxazines in good yields under an oxygen atmosphere.
A visible‐light, photoredox‐mediated oxidative tandem nitroso‐Diels–Alder reaction generates 3,6‐dihydro‐1,2‐oxazines from arylhydroxylamines and dienes via intermediary nitrosoarenes in the presence of Ru(bpy)3Cl2 (bpy = 2,2′‐bipyridine).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Cyclopentadienes are valuable intermediates in organic synthesis and also ubiquitous as the Cp ligands in organometallic chemistry. As part of ongoing efforts to develop novel organic reactions that ...employ functionalized alkynes, a 3+2 cycloaddition of propargylic alcohols and ketene dithioacetals has been developed, which leads to fully substituted 2,5‐dialkylthio cyclopentadienes in good to excellent yields. In an unusual dethiolating Diels–Alder reaction, the cyclopentadienes were further reacted with maleimides to afford a family of novel fluorescent polycyclic compounds.
2,5‐Dialkylthio cyclopentadienes were prepared by the BF3⋅Et2O catalyzed regiospecific 3+2 cycloaddition of propargylic alcohols and α‐oxo ketene dithioacetals in good to excellent yields. Furthermore, an unusual dethiolating Diels–Alder reaction of these cyclopentadienes with maleimides was discovered, which yielded novel fluorescent polycyclic compounds.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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