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We formulate and implement the Variational Quantum Eigensolver Self Consistent Field (VQE-SCF) algorithm in combination with polarizable embedding (PE), thereby extending PE to the regime of quantum computing. We test the resulting algorithm, PE-VQE-SCF, on quantum simulators and demonstrate that the computational stress on the quantum device is only slightly increased in terms of gate counts compared to regular VQE-SCF. On the other hand, no increase in shot noise was observed. We illustrate how PE-VQE-SCF may lead to the modeling of real chemical systems using a simulation of the reaction barrier of the Diels–Alder reaction between furan and ethene as an example. [ABSTRACT FROM AUTHOR]

A designed anthracene‐based monomer for topochemical Diels–Alder cycloaddition polymerization crystallized with head‐to‐tail arrangement of molecules, as revealed by single‐crystal X‐ray diffraction (SCXRD) analysis. The diene and dienophile units of adjacent monomer molecules are aligned at an average distance of 4.6 Å, suggesting a favorable crystalline arrangement for their intermolecular Diels–Alder cycloaddition reaction to form a linear polymer. Surprisingly, heating the monomer crystals at a temperature above 125 °C resulted in the formation of intramolecular Diels–Alder cycloadduct, which could be characterized by various spectroscopy and SCXRD analysis. Various time‐dependent studies such as NMR, PXRD, and DSC, studies established that the reaction followed topochemical pathway. Schmidt's topochemical postulates are generally used to predict the topochemical reactivity and product, by analyzing the crystal structure of the reactant. Though the crystal arrangement predicted polymerization, upon heating, the molecule avoided this pathway by undergoing a large rotation to form an intramolecular cycloadduct. Theoretical calculations supported the feasibility of the rotation, exploiting the flexibility of the molecule and voids present. These findings caution that the reliance on Schmidt's criteria for topochemical reactions may sometimes be misleading, especially in heat‐induced reactions. [ABSTRACT FROM AUTHOR]

Understanding the exohedral reactivity of metallofullerenes is crucial for its application in various fields. By systematically controlling the trapped species inside the fullerene its reactivity can be tamed. In this work we report the preferential position of 3d metal atoms inside the C36 cage and their effect on exohedral reactivity in comparison with the neutral and the dianionic cage. The Diels‐Alder (DA) reaction between butadiene and all non‐equivalent [5‐5], [6‐5] and [6‐6] C−C bonds on the fullerene cage was considered for the analysis, by using density functional theory at the S12g/TZ2P level including COSMO solvation model to elucidate the complete mechanistic pathways. Our results indicate that the preferential position of the metal ion is at the position close to the upper hexagon, and that the general trend in the reactivity of bonds follows the order [5‐5]>[6‐5]>[6‐6]. Moreover, the encapsulation of metal atoms further enhances the reactivity of these bonds, by lowering the LUMOs of the cage, hence maximizing the orbital interactions. [ABSTRACT FROM AUTHOR]

Comprehensive Summary A tandem Diels–Alder reaction/Claisen rearrangement/decarboxylation strategy of N‐allenamides (or aryloxyallenes) with 3‐alkoxycarbonyl‐2‐pyrones has been developed for the efficient synthesis of diarylmethanes with moderate to good yields. The reaction exhibits good functional group tolerance and can be applied to late‐stage modifications of known drug molecules. Mechanistic studies indicate that the ester group at the 3‐position of 2‐pyrones is essential, and the initial Diels–Alder reaction between the 2‐pyrones and the proximal C=C bond of the N‐allenamides (or aryloxyallenes) is crucial for the success of the reaction. [ABSTRACT FROM AUTHOR]

Understanding the exohedral reactivity of metallofullerenes is crucial for its application in various fields. By systematically controlling the trapped species inside the fullerene its reactivity can be tamed. In this work we report the preferential position of 3d metal atoms inside the C36 cage and their effect on exohedral reactivity in comparison with the neutral and the dianionic cage. The Diels‐Alder (DA) reaction between butadiene and all non‐equivalent [5‐5], [6‐5] and [6‐6] C−C bonds on the fullerene cage was considered for the analysis, by using density functional theory at the S12g/TZ2P level including COSMO solvation model to elucidate the complete mechanistic pathways. Our results indicate that the preferential position of the metal ion is at the position close to the upper hexagon, and that the general trend in the reactivity of bonds follows the order [5‐5]>[6‐5]>[6‐6]. Moreover, the encapsulation of metal atoms further enhances the reactivity of these bonds, by lowering the LUMOs of the cage, hence maximizing the orbital interactions. [ABSTRACT FROM AUTHOR]

Solvents can have a tremendous influence on the rate and selectivity of chemical reactions, but their effects are not always well accounted for. In the present work, density functional theory computations are used to investigate the influence of solvent on the Diels–Alder reactions of 9-methylanthracene with (5-oxo-2H-furan-2-yl) acetate and different anhydrides considering the overall reaction rates as well as selectivity between possible isomeric products. Crucially, we find that overall reaction rates are higher in non-polar toluene, whereas selectivity is enhanced in the polar solvent acetone. In the case of (5-oxo-2H-furan-2-yl) acetate, the difference in the reaction barriers is enhanced by 2.4 kJ/mol in acetone as compared to the gas phase, halving the yield of the side product. Similar results are found for the reaction of 9-methylanthracene with chloro-maleic anhydride and cyano-maleic anhydride, highlighting the generality of the trends observed. After presenting the energetics, a detailed discussion of the reactivity is given using electrostatic potentials, frontier orbitals, reactivity indices and Fukui functions. In summary, this study highlights the importance of solvent in influencing reaction rates and illustrates the possibility of studying its effects computationally. [ABSTRACT FROM AUTHOR]

Total syntheses of borolithochromes H1, H2, I1, and I2, the red pigments isolated from fossils of Jurassic putative red alga Solenopora jurassica , have been achieved. The naphthoquinone possessing a chiral sec -butyl side chain has been synthesized from (S)-2-methylbutanol. The Diels-Alder reaction of the chiral naphthoquinone and the previously reported diene was followed by one pot S-methylation/intramolecular Corey-Chaykovsky reaction/epoxide rearrangement to provide the benzo[ gh ]tetraphene skeleton. Complexation of the resulting ligand with trimethyl borate and the following O-demethylation furnished a 1:1 mixture of borolithochromes I1 and I2, which were separated by HPLC using CHIRALPAK IC® to afford optically pure borolithochromes I1 (6) and I2 (7). On the other hand, borolithochromes H1 and H2 were not separated by HPLC in our laboratory. Fortunately, the mixture of the methyl ethers of borolithochromes H1 and H2 were separated and O-demethylation with magnesium iodide furnished optically pure borolithochromes H1 (4) and H2 (5). [ABSTRACT FROM AUTHOR]

We report flexible synthesis of new unsymmetrically 2,6‐disubstituted benzoquinones (33 examples) and a systematic study of their reactivity in the Diels‐Alder reaction. The Diels‐Alder reactions of selected unsymmetrical benzoquinones with seemingly similar substituents were found to proceed with high regioselectivity and the formation of selected experimentally observed main products was rationalized by theoretical (DFT) calculations. The findings can be exploited in the convenient preparation of densely substituted and stereochemically defined decalins with unique angular substituents at ring fusion. We also demonstrate the usefulness of this methodology in complex molecule synthesis through the total synthesis of a novel forskolin analog possessing an ethyl group at the fusion of the rings B and C. [ABSTRACT FROM AUTHOR]

The New Journal of Chemistry, published by The Royal Society of Chemistry and the Centre National de la Recherche Scientifique, features a variety of papers on different topics in chemistry. The contents list includes papers on antimicrobial peptides, reduction of nitrophenols, supramolecular assembly, synthesis of heterometallic complexes, and the production of collagen-blended nanofiber matrices. Other topics covered in the journal include high entropy alloys, photophysical properties of helicenes, hydrated halogenides, combating multidrug-resistant bacteria, asymmetric synthesis, glucose oxidase intercalation, nanoplatforms for anti-tumor therapy, catalytic degradation of nerve agent simulants, and biological evaluation of novel compounds. The document also includes a correction for a previous paper on a zinc-porphyrin-peptide conjugate. [Extracted from the article]

Diels‐Alder (DA) cycloaddition of chalcones to anthracene and its 9‐substituted derivatives is an example of a demanding reaction that is not effective even under increased pressure. In this article we show that an easily accessible complex cation [Co(CH3NO2)6]2+ stabilized by weakly coordinating anion [Al(OC(CF3)3)4]− exhibits good catalytic activity in the reaction. Our screening covering chalcone and anthracene derivatives with either activating or deactivating effects on reactivity in DA cycloadditions show that the catalyst allows to obtain [4+2] cycloadducts with yields up to 99 % under mild conditions, even for 9‐bromoanthracene – a very poor diene in DA reactions. The reaction proceeds best in liquid SO2, which is an unusual solvent for this type of reaction. 9‐methylanthracene ‐ the most reactive diene among those tested in the study ‐ gives two regioisomeric cycloadducts and their ratio depends on the solvent used. Modeling of the reaction with DFT methods shows that Co(II) significantly lowers the activation energy of the cycloaddition. In the case of 9‐bromoanthracene the effect is much more pronounced than with e. g. recently reported redox‐activation of the diene, which is in agreement with much better yields obtained with the use of the cobalt catalyst. [ABSTRACT FROM AUTHOR]

The document is the contents list for the journal "Chemical Communications" published on September 14, 2024. It includes highlights, feature articles, and communications on various topics in chemistry. Some of the topics covered include transition metal complexes, electrochemical biosensors, and photochemical catalysis. The journal is published by The Royal Society of Chemistry, a leading chemistry community. [Extracted from the article]

The total syntheses of gochnatiolide D and ainsliadimer A were achieved through a streamlined one‐pot sequence starting from their biogenetic precursor dehydrozaluzanin C. These biomimetic, protecting group‐free syntheses involve the elegant orchestration of the highly diastereoselective hetero‐Diels‐Alder reaction of dehydrozaluzanin C, its subsequent hydrolysis to gochnatiolide D and finally an aldol reaction to ainsliadimer A, all harnessed by the hydrogen bond propensity and acidity of hexafluoroisopropanol (HFIP), which was utilized as the reaction solvent. [ABSTRACT FROM AUTHOR]

The Veratrum alkaloids are a class of highly intricate natural products renowned for their complex structural and stereochemical characteristics, which underlie a diverse array of pharmacological activities ranging from anti-hypertensive properties to antimicrobial effects. These properties have generated substantial interest among both synthetic chemists and biologists. While numerous advancements have been made in the synthesis of jervanine and veratramine subtypes over the past 50 years, the total synthesis of highly oxidized cevanine subtypes has remained relatively scarce. Building on the efficiency of our previously developed strategy for constructing the hexacyclic carbon skeleton of the Veratrum alkaloid family via a stereoselective intramolecular Diels-Alder reaction and radical cyclization, here we show the development of a unified synthetic approach to access highly oxidized Veratrum alkaloids. This includes the total synthesis of (–)-zygadenine, (–)-germine, (–)-protoverine and the alkamine of veramadine A, by capitalizing on a meticulously designed sequence of redox manipulations and a late-stage neighboring-group participation strategy. The Veratrum alkaloids are a class of highly intricate natural products renowned for their complex structural and stereochemical characteristics. Herein, the authors report the divergent synthesis of zygadenine, germine, protoverine and the alkamine of veramadine A, capitalizing on a late-stage neighboring group participation. [ABSTRACT FROM AUTHOR]

Solvents can have a tremendous influence on the rate and selectivity of chemical reactions, but their effects are not always well accounted for. In the present work, density functional theory computations are used to investigate the influence of solvent on the Diels–Alder reactions of 9-methylanthracene with (5-oxo-2H-furan-2-yl) acetate and different anhydrides considering the overall reaction rates as well as selectivity between possible isomeric products. Crucially, we find that overall reaction rates are higher in non-polar toluene, whereas selectivity is enhanced in the polar solvent acetone. In the case of (5-oxo-2H-furan-2-yl) acetate, the difference in the reaction barriers is enhanced by 2.4 kJ/mol in acetone as compared to the gas phase, halving the yield of the side product. Similar results are found for the reaction of 9-methylanthracene with chloro-maleic anhydride and cyano-maleic anhydride, highlighting the generality of the trends observed. After presenting the energetics, a detailed discussion of the reactivity is given using electrostatic potentials, frontier orbitals, reactivity indices and Fukui functions. In summary, this study highlights the importance of solvent in influencing reaction rates and illustrates the possibility of studying its effects computationally.

In the so-called Interacting Quantum Atoms (IQA) approach, the molecular energy is numerically decomposed as a sum of atomic and diatomic contributions. While proper formulations have been put forward for both Hartree–Fock and post-Hartree–Fock wavefunctions, this is not the case for the Kohn–Sham density functional theory (KS-DFT). In this work, we critically analyze the performance of two fully additive approaches for the IQA decomposition of the KS-DFT energy, namely, the one from Francisco et al., which uses atomic scaling factors, and that from Salvador and Mayer based upon the bond order density (SM-IQA). Atomic and diatomic exchange–correlation (xc) energy components are obtained for a molecular test set comprising different bond types and multiplicities and along the reaction coordinate of a Diels–Alder reaction. Both methodologies behave similarly for all systems considered. In general, the SM-IQA diatomic xc components are less negative than the Hartree–Fock ones, which is in good agreement with the known effect of electron correlation upon (most) covalent bonds. In addition, a new general scheme to minimize the numerical error of the sum of two-electron energy contributions (i.e., Coulomb and exact exchange) in the framework of overlapping atoms is described in detail. [ABSTRACT FROM AUTHOR]

The behavior of electrons during bond formation and breaking cannot commonly be accessed from experiments. Thus, bond perception is often based on chemical intuition or rule-based algorithms. Utilizing computational chemistry methods, we present intrinsic bond descriptors for the Diels–Alder reaction, allowing for an automatic bond perception. We show that these bond descriptors are available from localized orbitals and self-interaction correction calculations, e.g., from Fermi-orbital descriptors. The proposed descriptors allow a sparse, simple, and educational inspection of the Diels–Alder reaction from an electronic perspective. We demonstrate that bond descriptors deliver a simple visual representation of the concerted bond formation and bond breaking, which agrees with Lewis' theory of bonding. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate an Oxa‐Diels‐Alder reaction of 3‐trifluoroacetyl‐4‐methyl‐quinolin‐2(1H)‐one with aldehydes in the presence of a base to engineer the functionalized pyrano[3,4‐c]quinolones. This reaction proceeds through an in‐situ generated hetero dendralene intermediate and features perfect stereoselectivity on a wide range of substrates with excellent atom economy. The high electron‐withdrawing nature of CF3‐group is responsible for making the methyl group present in quinolone moiety more acidic to furnish the corresponding hetero dendralene intermediate. [ABSTRACT FROM AUTHOR]

The inherent chiral structures of DNA serve as attractive scaffolds to construct DNA hybrid catalysts for valuable enantioselective transformations. Duplex and G‐quadruplex DNA‐based enantioselective catalysis has made great progress, yet novel design strategies of DNA hybrid catalysts are highly demanding and atomistic analysis of active centers is still challenging. DNA i‐motif structures could be finely tuned by different cytosine‐cytosine base pairs, providing a new platform to design DNA catalysts. Herein, we found that a human telomeric i‐motif DNA containing cytosine‐silver(I)‐cytosine (C‐Ag+‐C) base pairs interacting with Cu(II) ions (i‐motif DNA(Ag+)/Cu2+) could catalyze Diels–Alder reactions with full conversions and up to 95 % enantiomeric excess. As characterized by various physicochemical techniques, the presence of Ag+ is proved to replace the protons in hemiprotonated cytosine‐cytosine (C : C+) base pairs and stabilize the DNA i‐motif to allow the acceptance of Cu(II) ions. The i‐motif DNA(Ag+)/Cu2+ catalyst shows about 8‐fold rate acceleration compared with DNA and Cu2+. Based on DNA mutation experiments, thermodynamic studies and density function theory calculations, the catalytic center of Cu(II) ion is proposed to be located in a specific loop region via binding to one nitrogen‐7 atom of an unpaired adenine and two phosphate‐oxygen atoms from nearby deoxythymidine monophosphate and deoxyadenosine monophosphate, respectively. [ABSTRACT FROM AUTHOR]

Kekulene, a cycloarene composed of 12 fused benzene rings in a circular arrangement, exhibits a highly planar and robust structure. Kekulene has been the subject of investigation into its aromaticity and electronic structure, particularly in relation to the cyclic benzenoid. We have successfully synthesized novel bowl‐shaped kekulene analogues with five‐membered rings incorporated into the kekulene structure. The results of DFT calculations and VT‐NMR spectra indicate that inversion of their concave‐convex structures occurs at room temperature. The NICS and AICD plots predict that the Clar's type resonance structure is found in a manner analogous to the pristine kekulene, albeit with the interruption of the π‐conjugation on the sp3 carbons at the five‐membered rings. Despite the presence of the Clar's resonance structure, the Diels‐Alder reaction proceeded smoothly with a dienophile, in contrast to the behavior of planar kekulene derivatives. This study will lead to the creation of novel bowl‐shaped compounds and development of reactivity in aromatic compounds. [ABSTRACT FROM AUTHOR]

Enantioselective total synthesis of (+)-sapinsigin H, (+)-agallochaol C, and (+)-16α, 17-dihydroxy-atisan-3-one has been accomplished starting from enantiopure Wieland–Miescher ketone. Key features of the syntheses include a benzannulation step to construct the tricyclic core, an oxidative dearomatization step to generate the diene, and a Diels–Alder reaction with ethylene gas to establish the bicyclo[2.2.2]octane framework. Efficient late-stage functionalisation of the A-ring by aerobic oxidation and Baeyer−Villiger oxidation completed the atisane target molecules. [ABSTRACT FROM AUTHOR]

A novel meroterpenoid cabagranin D was isolated with related neolignans cabagranins A-C from the leaves of Piper cabagranum (Costa Rica). Cabagranins A-C represent the first examples of 3,3'-neolignans isolated from the plant genus Piper, and the meroterpenoid cabagranin D displays an unprecedented Diels-Alder conjugate of an unsubstituted phenylpropenone and α-phellandrene. Details of the full structural elucidation of these compounds and a discussion of their potential biosynthetic relationships are presented. [ABSTRACT FROM AUTHOR]

The formal kinetics of the interaction of acrylonitrile (AN) and cyclopentadiene (CPD) by the Diels–Alder reaction in the presence of industrial zeolites has been studied. The dependence of the reaction rate constants of interacting components on the geometric properties of porous materials was revealed. The established dependence had a negative extremum at a zeolite pore diameter of 4 Å. It was shown that, in the presence of zeolites, the rate constant of the reaction under consideration was lower than that in the reaction carried out without porous materials. [ABSTRACT FROM AUTHOR]

Based on transition state shape selectivity (TSSS) conception, as general model, we have evaluated the zeolites topology influence on the reaction rate of acrylonitrile with piperylene. Theoretical modeling was carried out for the set of zeolites with cavities diameters: KA (3 Å), NaA (4 Å), CaA (5 Å), CaX (8 Å), NaX (9 Å). The estimated parameter was the "frozen" transition state (TS) adsorption energy in the cavities and its dependence on the diameter of the zeolite cavity. Also, we compared theoretical dependence with found in experiment dependence of the effective reaction rate constants (k, s−1) for reaction between acrylonitrile and piperylene in the presence of zeolite on the cavity diameter of zeolites. Both dependences have extremal character and maximum value of rate constant is observed for zeolite CaA with cavity diameter 5 Å. Thus, the effective rate of the product formation reaction in the absence of zeolites was 1.67 ∙ 10–4 s−1, and in the presence of zeolite CaA 3.23 ∙ 10–4 s−1. Thus, in the presence of zeolite, the reaction accelerated 1.9 times. Theoretical modeling prognoses the best transition state stabilization and, as consequences most energy activation decrease, at the same zeolite cavity diameter. This result is well explained by the comparability of the dimension of the TS and the cavity of the zeolite in which the reaction occurs. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) is an endogenously produced molecule and has shown efficacy in animal models of inflammation, organ injury, colitis and cancer metastasis. Because of its gaseous nature, there is a need for developing efficient CO delivery approaches, especially those capable of targeted delivery. In this study, we aim to take advantage of a previously reported approach of enrichment-triggered prodrug activation to achieve targeted delivery by targeting the folate receptor. The general idea is to exploit folate receptor-mediated enrichment as a way to accelerate a bimolecular Diels-Alder reaction for prodrug activation. In doing so, we first need to find ways to tune the reaction kinetics in order to ensure minimal reaction without enrichment and optimal activation upon enrichment. In this feasibility study, we synthesized two diene-dienophile pairs and studied their reaction kinetics and ability to target the folate receptor. We found that folate conjugation significantly affects the reaction kinetics of the original diene-dienophile pairs. Such information will be very useful in future designs of similar targeted approaches of CO delivery. [ABSTRACT FROM AUTHOR]

A new heptaketide named oryzanigral (1) was isolated from the fermentation extract of the endophytic fungus Nigrospora oryzae isolated from the leaves of Coccinia grandis, along with five known compounds, (R)-mellein, (R)-O-methylmellein, (3R,4R)-4-hydroxymellein, (3R,4S)-4-hydroxymellein and abscisic acid. The structure of oryzanigral was elucidated by spectroscopic analyses including 2D-NMR. A plausible biosynthetic pathway involving Diels-Alder reaction was proposed for compound 1 and related polyketides previously reported. In addition, structure revision of the double bond geometry for coicenal A was described. [ABSTRACT FROM AUTHOR]

Within the context of Molecular Electronic Density Theory (MEDT), this study investigates the Diels–Alder reaction among isoprene (2) and R-carvone (1R) applying DFT simulations, with and without Lewis acid (LA) catalysis. The results show that carvone (1R) acts as an electrophile and isoprene (2) as a nucleophile in a polar process. LA catalysis increases the electrophilicity of carvone, thereby improving the reactivity and selectivity of the reaction by reducing the activation Gibbs free energy. Parr functions reveal that the C5=C6 double bond is more reactive than the C9=C10 double bond, indicating chemoselectivity. The examination of the Electron Localization Function (ELF) reveals high regio- and stereoselectivity, indicating an asynchronous mechanism for the LA-catalyzed DA reaction. Furthermore, it is suggested that cycloadduct 3 has great anti-HIV potential because it exhibits lower binding energies than azidothymidine (AZT) in the docking studies of cycloadducts 3 and 4 amongst a primary HIV-1protein (1A8O plus 5W4Q). [ABSTRACT FROM AUTHOR]

Ferrocene-substituted carbenes have emerged as attractive, redox-active ligands. However, among the compounds studied to date, ferrocenylated 1,2,4-triazol-5-ylidenes, which are closely related to the archetypal imidazol-2-ylidenes, are still unknown. Here, we demonstrate that the triazolium salt [CHN(Me)NCHN(Fc)]I (2; Fc = ferrocenyl), obtained by alkylation of 4-ferrocenyl-4H-1,2,4-triazole (1) with MeI, reacts selectively with metal alkoxide/hydroxide precursors [(cod)Rh(OMe)]2 and [(IPr)Au(OH)] (cod = cycloocta-1,5-diene, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) to produce the ferrocene-substituted 1,2,4-triazol-5-ylidene complexes [(cod)RhI{CN(Me)NCHN(Fc)}] and [(IPr)Au{CN(Me)NCHN(Fc)}]I in good yields. The complexes were characterised by NMR and IR spectroscopy, mass spectrometry, cyclic voltammetry, and single-crystal X-ray diffraction analysis. Density function theory (DFT) calculations were used to rationalise the electrochemical behaviour of the carbene complexes and to elucidate the bonding situation in these compounds. An analysis using intrinsic bond orbitals (IBOs) revealed that the 1,2,4-triazol-5-ylidene ligand exerted a strong trans influence and showed a synergistic stabilisation by the negative inductive and positive π-donor effects of the nitrogen atoms adjacent to the carbene carbon atom; these effects were enhanced by conjugation with the CH＝N bond at the exterior, similar to that in imidazol-2-ylidenes. [ABSTRACT FROM AUTHOR]

Divergent nitrogen‐containing fused polycyclic ring systems are constructed from simple starting materials via a one‐pot aldehyde‐alkyne‐amine (A3) coupling and intramolecular Diels‐Alder reaction. This domino reaction directly furnishes linear 5/5/5 and 5/5/6, or nonlinear 5/5/6/5, polycyclic rings containing an oxa‐bridged fused 5/5 bicycle and a 1,6‐enyne substructure. One‐step derivation of the oxa‐bridged 5/5 bicycle leads to a polyfunctionalized 5/5 bicycle with tetrahydrofuran fused back‐to‐back to pyrroline or a 6/5 bicycle with the hexahydro‐1H‐isoindole structure, while cycloisomerizing the enyne substructure adds an extra fused 5‐membered ring to afford functionalized linear 5/5/5/5 or 5/5/5/5/5 fused ring systems from selected substrates. In addition, the one‐pot product can be designed so that the alkyne moiety is hydroalkoxylated to form an additional heterocyle in a linear 5/5/5/6 or nonlinear 5/5/6/5/5 ring system. This diversity‐oriented synthetic approach thus allows rapid access to an under‐explored structural space for discovery of new biological or non‐biological activities or functions. [ABSTRACT FROM AUTHOR]

Pulsed ultrasonic irradiation with on‐off modulation remarkably enhances asymmetric noncovalent organocatalysis "on water", specifically for Michael addition and Diels‐Alder reactions. This approach effectively addresses challenges associated with solid reactant dispersion encountered in "on‐water" reactions and mitigates overheating issues caused by continuous ultrasound exposure, thereby significantly augmenting reaction rates and stereoselectivities. [ABSTRACT FROM AUTHOR]

This article explores the advancements in stereodivergent carbon-carbon bond-forming reactions in organic chemistry. These reactions allow for the control of multiple stereogenic centers in a reaction, providing synthetic chemists with more flexibility and efficiency in constructing complex molecular structures. The article emphasizes the importance of these methods in drug discovery, where different stereoisomers of a drug can have different biological activities. The field of stereodivergent catalysis has grown significantly, with mono-catalytic and bifunctional catalytic methods contributing to the development of these reactions. Dual catalysis faces challenges, but progress has been made in finding compatible reaction types. The ultimate challenge lies in achieving high yields of multiple stereoisomers, but advancements in high-throughput experimentation and catalyst optimization may help overcome this challenge. [Extracted from the article]

This document provides information on the synthesis of the dopamine agonist Rotigotine, which is used to treat Parkinson's disease and restless leg syndrome. The authors discuss different synthetic approaches and successfully synthesized Rotigotine using reductive amination with a high yield. The document also includes information on the synthesis and characterization of three compounds related to Rotigotine, along with their spectral data. Additionally, it provides details on the synthesis and chiral separation of (±)-Rotigotine, including its chemical structure, physical properties, and analytical data. The authors acknowledge Chemveda Life Sciences for their assistance in the separation process. [Extracted from the article]

New 2‐(di)methoxythienyl substituted ligands of the 2,2′‐bipyridine series containing various aromatic substituents at the C3 position were obtained in yields of up to 90 %. A "1,2,4‐triazine" methodology involving an SNH reaction in 1,2,4‐triazine followed by an aza‐Diels‐Alder reaction with 2,5‐norbornadiene was used to synthesize the target compounds. When the Diels‐Alder reaction was carried out in an autoclave, an unexpected demethylation reaction was observed, leading to the formation of oxo‐thienyl substituted products. A mechanism for the reaction that occurred has been proposed on the basis of identified byproducts. Preliminary studies on the photophysical and coordination properties of the obtained compounds were also carried out. In particular, the possibility of obtaining a platinum(II) complex with the demethylation product was demonstrated. [ABSTRACT FROM AUTHOR]

Stimuli‐responsive surfaces have garnered intensive research attention in addressing the challenges of severe information leakage problems, but they exhibit limitations in terms of intricate preparation and compatibility. Herein, the study reports a time‐dependent wrinkled surface controlled by photo‐induced stress relaxation of azobenzene‐ containing crosslinked polymer network comprised of furan‐containing polymer (PEA‐Fu) and maleimide‐substituted azobenzene (AZO‐2MI) as skin layer. Two kinds of wrinkled surfaces induced by two crosslinked networks (thermal‐ and UV‐induced) can be prepared by Diels‐Alder reaction and UV‐induced radical coupling reaction, exhibiting distinct amplitude decrease rate resulted from different stress relaxation rate induced by photo‐isomerization of azobenzene. By UV preprogramming with photomasks, various time‐dependent wrinkle patterns are obtained and can be identified at specific times under 450 nm irradiation. The time window for information read out can be preset through different UV preprogramming time and boundary conditions to achieve multi‐level information encryption. Furthermore, the written information can be camouflaged as another “false” information by regional‐selective irradiation under 450 nm irradiation, which offers a new method for information protection. Based on distinctive time‐dependent characteristics and excellent stability, this responsive wrinkled surface offers bright prospects in multi‐level information encryption. [ABSTRACT FROM AUTHOR]

Transition‐metal‐catalyzed [4+4] cycloaddition leading to cyclooctanoids has centered on dimerization between 1,3‐diene‐type substrates. Herein, we describe a [4σ+4π−1] and [4σ+4π] cycloaddition strategy to access 7/8‐membered fused carbocycles through rhodium‐catalyzed coupling between the 4σ‐donor (benzocyclobutenones) and pendant diene (4π) motifs. The two pathways can be controlled by adjusting the solvated CO concentration. A broad range (>40 examples) of 5–6–7 and 5–6–8 polyfused carbocycles was obtained in good yields (up to 90 %). DFT calculations, kinetic monitoring and 13C‐labeling experiments were carried out, suggesting a plausible mechanism. Notably, one 5–6–7 tricycle was found to be a very rare, potent, and selective ligand for the liver X receptor β (KD=0.64 μM), which is a potential therapeutic target for cholesterol‐metabolism‐related fatal diseases. [ABSTRACT FROM AUTHOR]

Highlights Epoxy asphalt, a thermosetting polymer, is characterized by stable, irreversible internal chemical bonds that prevent recovery and spontaneous micro‐crack healing, unlike conventional asphalt. This study introduces a renewable nano‐modifier synthesized via esterification of carboxyl‐functionalized carbon nanotubes (CNTs‐COOH) and furfuryl alcohol (FA), termed CNTs‐FA. The successful synthesis of CNTs‐FA was confirmed through various microscopic techniques. Integrating CNTs‐FA into epoxy asphalt materials, the optimal dosage was identified as 0.05% of the total epoxy asphalt mass using tensile tests and fluorescence microscopy. Thermal reversible effects and mechanisms were further analyzed through multiple regeneration cycles using tensile properties, fluorescence microscopy, and infrared spectroscopy. The study elucidates that the thermal reversibility in epoxy asphalt is facilitated by the Diels‐Alder (DA) reaction between the conjugated diene structure in FA and the curing agent oleylamine. This research provides an effective solution to the non‐recoverability and unrepairable micro‐cracks of traditional epoxy asphalt mixtures. CNTs‐FA was successfully prepared by esterification reaction. Using nano modification methods, introduce DA reaction into curing system. Renewable function of epoxy asphalt by DA reversible reaction. [ABSTRACT FROM AUTHOR]

Recyclability of polyurethane materials is significant to relieve environmental problems caused by damaged polymers. Inspired by plenty of self‐healing properties based on dynamic covalent bonds. A high mechanical strength and thermally reversible polyurethane adhesive are acquired through co‐polymerization of poly‐1,4‐butylene adipate glycol (PBA), soybean oil‐based polyol (MESO), and toluene diisocyanate (TDI) whose linear polymer chains are constructed by Diels–Alder reaction between furfuryl alcohol (FA) and bismaleimide (BMI), named DAPU. Further, the obtained polyurethane adhesives show great recyclability, mechanical performance (Whose tensile strength can reach 91.7 MPa), and appropriate self‐healing ability through the thermally reversible Diels–Alder covalent bonds and hydrogen bonds between urethane groups, which may pave a way for further development of recyclable materials. [ABSTRACT FROM AUTHOR]

A highly stereoselective synthesis of fused heterocycles with multiple stereocenters via an internal redox reaction/inverse electron-demand hetero-Diels–Alder (IEDHDA) reaction sequence is described. The present reaction sequence has three interesting features: (1) complete control of two potentially competitive processes, i.e., hetero-Diels–Alder reaction and [1,5]-hydride shift; (2) one-shot construction of the complicated 6/7/6-fused heterocyclic structure having multiple stereocenters; and (3) high control of its stereoselectivity. When alkenylidene barbiturates with an allyl benzyl ether moiety were treated with a catalytic amount of Sc(OTf)3 and 2,2′-bipyridine, the internal redox reaction/IEDHDA reaction proceeded successively to afford 6/7/6-fused heterocycles in good chemical yields with good to excellent diastereoselectivities. [ABSTRACT FROM AUTHOR]

Synthesis of the A/D/E-ring core compounds of maoecrystal V was achieved. The key Diels-Alder reactions between tricyclic α-methylene lactones and Kitahara-Danishefsky dienes afforded the spirocyclic core compounds in a regioselective and stereoselective manner. [ABSTRACT FROM AUTHOR]

The Diels–Alder (DA) reaction, specifically referring to the [4 + 2] cycloaddition reaction in pericyclic reactions, is a process that forms two carbon-carbon covalent bonds in a single step via an electron ring transition state. Among the secondary metabolites produced by microorganisms, numerous compounds are biosynthesized through DA reactions, most of which are enzymatic. Our research group has discovered an enzyme named Diels–Alderase (DAase) that catalyzes the DA reaction in filamentous fungi, and we have been investigating its catalytic mechanism. This review describes the reported microbial DAase enzymes, with a particular focus on those involved in the construction of the decalin ring. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The first total synthesis of talaroconvolutin A (1.1 g obtained) and talarofuranone has been achieved using accessible materials (12 steps, 7.5% and 8.2% yields, respectively). Convergent routes involved intramolecular Diels−Alder reactions in two approaches for creating the decalin moiety. Additionally, an unprecedented DMP‐mediated domino reaction resulted in the deoxy‐tetramic acid system. These syntheses not only establish the absolute configuration of talaroconvolutin A but also enable further collaborative studies of this type of ferroptosis inducers. [ABSTRACT FROM AUTHOR]

This article provides an overview of the field of bioorthogonal chemistry and its advancements at Radboud University. Bioorthogonal chemistry involves conducting chemical reactions within a biological environment with high selectivity and compatibility. Radboud University has made significant contributions to this field, including the development of strained alkynes and the synthesis of bioorthogonal tools such as BCN and TCO. These tools have been applied in various areas such as chemical biology and materials science. The article also highlights the interdisciplinary nature of research at Radboud University and the importance of synthetic availability in bioorthogonal reagents. The text specifically discusses the use of VBAs in bioorthogonal chemistry, particularly in the IEDDA reaction with tetrazines. The authors found that introducing boronic acid substituents on linear alkenes improved their reactivity in the IEDDA reaction. They also observed that the reactivity of VBAs varied depending on the coordinating substituent on the tetrazine. The authors explored the potential of VBAs in click-to-release chemistry, protein modification, and drug delivery applications. The article emphasizes the collaborative efforts and interdisciplinary approach necessary for advancing bioorthogonal chemistry. [Extracted from the article]

A fruitful debate took place recently in literature, discussing the enhanced Diels–Alder reactivity of tropone derivatives for which the carbonyl polarity was reversed by means of umpolung. Karas et al. sustained that the umpolung increases the antiaromatic character of the ring, affecting the highest occupied molecular orbital (HOMO)/least unoccupied molecular orbital (LUMO) energies, speeding up the reaction. Tiekink et al. challenged this interpretation by sustaining that the asynchronicity of the reaction mechanisms, rather than orbital energy perturbation, was the main responsible for the smaller reaction barriers. We shed light on this dispute by computing full interaction quantum atom (IQA) and quantum theory of atoms in molecules (QTAIM) analyses over complete intrinsic reaction coordinate (IRC) paths for the Diels–Alder reaction of tropone and its umpolung derivatives, using the same systems studied by Karas et al. and Tiekink et al. Our results confirm that the asynchronicity is indeed very high for those reactions with smaller reaction barriers and offer an atom‐by‐atom and bond‐by‐bond analysis of the entire IRC pathways. Even though asynchronicity and lower reactions barriers seem to be related, antiaromaticity and lower barriers are related as well, but discussing both these interpretations does not necessarily require arguments on HOMO/LUMO energies to be invoked. [ABSTRACT FROM AUTHOR]

This document discusses the importance of catalysis in chemical production and highlights the extensive research conducted in this field. It covers various aspects of catalysis, including different research fields, specific catalysts, countries, companies, and collaborations. The document also pays tribute to Professor Jiro Tsuji, a renowned scientist in the field of organic chemistry and catalysis, who made significant contributions to the development and application of transition metal-catalyzed reactions. The special issue of Catalysts is dedicated to Professor Tsuji and includes papers on various topics related to catalysis, including green methods, photocatalysis, and electrochemistry. The document concludes by acknowledging the valuable contributions of the authors and expressing gratitude to the editorial team. [Extracted from the article]

This article discusses a new method for synthesizing homoallylic alcohols, which are commonly found in synthetic intermediates and bioactive molecules. The authors describe a three-component reaction using specific catalysts, which allows for the creation of a diverse range of homoallylic alcohols. The article also includes detailed procedures for the synthesis and purification of these compounds, as well as their characterization using various analytical techniques. The information is presented in a technical manner and is intended for researchers in the field. [Extracted from the article]

The reaction characteristics of FOX-7 and NH2/NO2-substituted oxazole compounds in the Diels–Alder reaction were studied, based on which six series of novel bridge-ring energetic compounds were designed. The reaction feasibility, energetic properties and stability of the designed compounds were extensively evaluated based on density functional theory. The preferred dienes tend to undergo normal or inverse Diels–Alder reactions with FOX-7. And, the formation of the most designed bridge-ring energetic compounds tends to follow a two-step reaction mechanism rather than the common one-step concerted cycloaddition mechanism. All the designed bridge-ring energetic compounds exhibited excellent detonation performance, except for P1 and P2 series compounds. In a comprehensive evaluation of detonation performance and stability, compounds P6-1 and P6-3 (ρ > 2.08 g cm−3, D > 9800 m s−1, P > 44 GPa, h50 values are comparable to that of CL-20) and compounds P4-1, P4-4, P5-1, and P5-4 (ρ: 1.952–1.976 g cm−3, D: 9474–9508 m s−1, P: 40.5–41.5 GPa, h50 values are superior to that of CL-20) are the most promising high-energy-density compounds. This study can provide some guidance for the extension of the derivative reaction of FOX-7, as well as the design and experimental synthesis of these novel bridge-ring energetic compounds. [ABSTRACT FROM AUTHOR]

Herein, we present catalyst‐regulated switchable site‐selective hydrosilylation of enynes, which are suitable for a wide range of alkyl and aryl substituted polar enynes and exhibit excellent functional group compatibility. Under the optimized conditions, silyl groups can be precisely installed at various positions of 1,3‐dienes. While α‐ and γ‐silylation products were obtained under platinum‐catalytic systems, β‐silylation products were delivered with [Cp*RuCl]4 as catalyst. This process lead to the formation of 1,3‐dienoates with diverse substitutions, which would pose challenges with other methodologies. [ABSTRACT FROM AUTHOR]

The article discusses the challenges and strategies involved in the dearomatization of ¿-unsubstituted ß-naphthols in organic synthesis. It explores various methods, including catalytic reduction reactions, Lewis acid catalysis, transition-metal-catalyzed reactions, and gold-catalyzed reactions, which offer efficient ways to synthesize complex spirocyclic molecules and functional spiro polymers. The article also acknowledges the limitations and challenges associated with these reactions. It concludes by suggesting that new strategies for catalytic asymmetric dearomatization reactions will likely be discovered in the future. [Extracted from the article]

This article discusses the development of a nickel-catalyzed hydroalkynylation reaction of 1,3-dienes with simple alkynes. The researchers used a Xantphos ligand to achieve regioselective hydroalkynylation, producing a variety of allylic alkyne products. They optimized the reaction conditions by adding water, which increased the yield of the desired product. The method demonstrated excellent functional-group tolerance and a wide substrate scope for alkynes. The researchers also proposed a mechanism for the reaction based on previous studies. Further research will focus on asymmetric variants, expanding the reaction scope, and exploring synthetic applications. [Extracted from the article]

This document discusses a copper-catalyzed oxa-Diels-Alder reaction that allows for the synthesis of functionalized isochromans, which are important in organic synthesis and have applications in natural products and pharmaceuticals. The authors used sultines as reactants, which undergo a reaction to generate reactive intermediates that can react with aldehydes and ketones. The presence of a copper catalyst suppresses unwanted byproducts and allows for the synthesis of a variety of substituted sultines and carbonyl compounds. The method is simple and provides good yields of functionalized isochromans. [Extracted from the article]

Here we report B(C6F5)3/CPA‐catalyzed enantioselective aza‐Diels–Alder reaction of 3,3‐difluoro‐2‐Aryl‐3H‐indoles with unactivated dienes to access chiral 10,10‐difluoro‐tetrahydropyrido[1,2‐a]indoles. This protocol allows the formation of pyrazole‐based C2‐quaternary indolin‐3‐ones with high enantioselectivities and regioselectivities. Moreover, gram‐scale synthesis of the 10,10‐difluoro‐tetrahydropyrido[1,2‐a]indole skeleton was successfully achieved without any reduction in both yield and enantioselectivity. [ABSTRACT FROM AUTHOR]