Vinylic Research Articles

Water-catalyzed iron-molybdenum carbyne formation in bimetallic acetylene transformation

Transition metal carbyne complexes are of fundamental importance in carbon-carbon bond formation, alkyne metathesis, and alkyne coupling reactions. Most reported iron carbyne complexes are stabilized by incorporating heteroatoms. Here we show the synthesis of bioinspired FeMo heterobimetallic carbyne complexes by the conversion of C2H2 through a diverse series of intermediates. Key reactions discovered include the reduction of a μ-η2:η2-C2H2 ligand with a hydride to produce a vinyl ligand (μ-η1:η2-CH = CH2), tautomerization of the vinyl ligand to a carbyne (μ-CCH3), and protonation of either the vinyl or the carbyne compound to form a hydrido carbyne heterobimetallic complex. Mechanistic studies unveil the pivotal role of H2O as a proton shuttle, facilitating the proton transfer that converts the vinyl group to a bridging carbyne.

Electrochemical Homo- and Crossannulation of Alkynes and Nitriles for the Regio- and Chemoselective Synthesis of 3,6-Diarylpyridines.

We disclose a mediated electrochemical [2+2+2] annulation of alkynes with nitriles, forming substituted pyridines in a single step from low-cost, readily available starting materials. The combination of electrochemistry and a triarylamine redox mediator obviates the requirements of transition metals and additional oxidants. Besides the formation of diarylpyridine moieties via the homocoupling of two identical alkynes, the heterocoupling of two different alkynes depending on their electronic nature is possible, highlighting the unprecedented control of chemoselectivity in this catalytic [2+2+2] process. Mechanistic investigations like cyclic voltammetry and crossover experiments combined with DFT calculations indicate the initial oxidation of an alkyne as the key step leading to the formation of a vinyl radical cation intermediate. The utilization of continuous flow technology proved instrumental for an efficient process scale-up. The utility of the products is exemplified by the synthesis of π-extended molecules, being relevant for material or drug synthesis.

Ionic liquid-derived carbon dots with enhanced antibacterial activity and antibiofilm capability for treatment of MRSA-infected wounds

Bacterial resistance to antibiotics has rendered bacterial infections an escalating threat to public health, prompting numerous researchers to strive towards the development of novel antimicrobial agents. Designable ionic liquids (ILs) have gained increasing prominence in the field of antibacterials. However, certain ILs exhibit suboptimal antimicrobial activity. In this study, we synthesized ionic liquid-derived carbon dots (IL-CDs: VOIMBr-CD) through vinyl and epoxy group reactions, resulting in enhanced antimicrobial efficacy. The VOIMBr-CD retains the antibacterial structure characteristic of ILs, including a positively charged imidazolium group and long alkyl chain. Moreover, VOIMBr-CD demonstrates selective antibacterial action against Staphylococcus aureus (S. aureus) while effectively inhibiting S. aureus biofilm growth. Notably, the antibacterial efficacy of VOIMBr-CD against methicillin-resistant Staphylococcus aureus (MRSA), surpasses vancomycin (Van). We conducted comprehensive investigations into the selective antibacterial mechanism of VOIMBr-CD which primarily involves electrostatic interactions, hydrophobic interactions, as well as generation of reactive oxygen species (ROS) within bacteria cells. In vivo experiments demonstrated that VOIMBr-CD significantly alleviate inflammation, facilitated collagen deposition and angiogenesis, and effectively expedited wound healing in MRSA-infected mice models; thus, highlighting their potential as therapeutic candidates for diseases resembling MRSA infection-like conditions. Importantly, this work presents a novel approach utilizing IL-based materials for developing effective antibacterials thereby offering new insights into the application prospects of IL-derived materials.

Acrylate-Based PEG Hydrogels with Ultrafast Biodegradability for 3D Cell Culture.

Poly(ethylene glycol) (PEG)-based hydrogels are particularly challenging to degrade, which hinders efficient cell harvesting within the gel matrix. Here, highly branched copolymers of PEG methyl ether acrylate (PEGMA) and disulfide diacrylate (DSDA) (PEG-DS) with short primary chains and multiple pendent vinyl groups were synthesized by a "vinyl oligomer combination" approach. PEG-DS readily cross-links with thiolated gelatin (Gel-SH) to form hydrogels. Results demonstrate that shortening the primary chains of PEG-DS significantly enhances the viability of bone marrow mesenchymal stem cells (BMSCs) by up to 193.2%. Importantly, DS junctions can be easily cleaved into short primary chains using dithiothreitol (DTT), triggering ultrafast degradation of PEG-DS/Gel-SH hydrogels within 2 min under mild conditions and release of the encapsulated BMSCs. This study establishes a novel strategy to enhance the degradation of acrylate-based PEG hydrogels for three-dimensional (3D) cell culture and harvesting. These findings expand the potential applications of such hydrogels in various biomedical fields.

Photopolymerization of polyvinylethylene glycol oligomers by thiol‐ene click reaction

AbstractFunctional polyvinylethylene glycols (PVEGs) with pendent vinyl groups were synthesized by Pd/B synergistic catalysts and their structures were characterized by 1H NMR and FT‐IR. The photopolymerization of the obtained PVEGs with multifunctional thiols in the presence of a photoinitiator proceeded smoothly via thiol‐ene photo‐click reaction to give a series of crosslinked materials by the variation of the molecular weight of PVEGs and a ratio of thiols and enes. The curing behavior was studied by FT‐IR and the properties of crosslinked materials were characterized by the test of gel content, swelling ratio, and water absorption. The dynamic mechanical analysis, mechanical properties, thermogravimetry, and surface properties of the crosslinked materials were investigated and the performance of coating for the crosslinked film materials was also characterized. The crosslinked film materials can be further functionalized by post‐crosslinking modification through thiol‐ene photo‐click reaction.

Backbiting-minimized synthesis of fluorosilicone copolymers with promoter by anionic ring-opening polymerization

A back-biting reaction in fluorosilicone synthesis can compromise its precision–manufactured mechanical properties and deteriorate its molecular properties. This phenomenon can potentially disrupt the intricate structure of fluorosilicone, diminishing its durability and altering its properties over time. Cyclosiloxane with methyl and vinyl groups was added to overcome the limited properties of poly[methyl(trifluoropropyl)siloxane] and conventional rubber for harnessing versatile materials, such as vehicles and spacecraft. In this study, dimethyl carbonate, diethyl carbonate, and allyl methyl carbonate were used as promoters to suppress back-biting reactions, and an improved fluoro-vinyl-methyl silicone (FVMQ) was synthesized. 29Si nuclear magnetic resonance (NMR) spectroscopy showed that the cyclic by-products from the back-biting reaction were inhibited by adding carbonate materials. Moreover, the conversion of 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane also increased as the amount of promoter increased. The roles of varying carbonate promoters in altering the properties of FVMQs were studied using 1H NMR spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. Furthermore, the intermediate of FVMQs was prepared and analyzed using Fourier transform infrared spectroscopy, 1H NMR spectroscopy, and gel permeation chromatography to determine the mechanism of suppressing back-biting. The results showed that controlled synthesis of FVMQs by inhibiting the production of cyclic by-products with promoters will improve silicone polymer synthesis and the vehicle industry requiring high yields of fluorosilicone copolymers.

Microwave Spectroscopy of Chiral Astrochemical Candidate Vinyloxirane: The Missing Gauche Conformer.

The recent detection of a chiral molecule, propylene oxide, in the interstellar medium provides impetus for investigation of related analogues as candidates for discovery of a second chiral species. Vinyloxirane (VO) shares many of the characteristics of propylene oxide that favored its remote detection such as modest size, appreciable dipole moment and modest adsorption to water ice. The microwave spectrum of vinyloxirane at room temperature has been studied in the 18 - 26 GHz region. Rotational transitions of the previously undetected gauche-1 conformer have been assigned and fitted. The quantum number range of anti conformer transitions has been greatly expanded, providing improved molecular constants. Vibrational satellite transitions were assigned and fitted for the lowest frequency ν27 torsion mode, for 2ν27, and for the ν26 C=CC bend of anti VO, along with ν27 satellites of gauche-1. The rovibrational analyses were assisted by anharmonic vibrational calculations at B3LYP-D3/aug-cc-PVTZ, B2PLYPD3/cc-pVTZ, and DSDPBEP86/cc-pVTZ levels. Experimental peak intensities provide a population ratio Ngauche-1/Nanti of 0.36 ± 0.06, corresponding to a Gibbs free energy difference of 2.5 ± 0.4 kJ mol-1 in favor of the anti conformer, in agreement with the density functional theory results. In the gauche-1 conformer, the torsional angle between vinyl group and oxirane ring, τC=CCM, is optimized at -35° to favor an intramolecular CvinylH11...O interaction. The gauche-2 conformer with τC=CCM of + 74° suffers from CvinylH11...HCcyclopropyl repulsion so that it is calculated to be 8-9 kJ mol-1 higher than gauche-1. Reinterpretation of earlier Raman spectra suggests that the gauche-2 conformer had not been observed as reported.

Hydrophilic coating of membrane by UV-induced radical and cationic curing of photosensitive resins: Lower shrinkage, smoother surface and better anti-fouling performance

Hydrophilic coating is frequently used to enhance the anti-fouling performance of membrane. However, traditional strategies often suffer from defects of cumbersome steps, high energy consumption, and unstable coating. Herein, radical and cationic photopolymerization are used for hydrophilic coating of membranes. Two photosensitive resins were first synthesized either by direct radical copolymerization of 3-ethyl-3-(methacryloyloxy) methyloxetane and 2-hydroxyethyl acrylate (Poly(HEA-EMO)) or through post-polymerization modification of poly(2-hydroxyethyl acrylate) with vinyl groups (Poly(HEA-MA)). Subsequently, hydrophilic coating was conducted on the membrane surface by UV-induced curing of different photosensitive resins, either through radical photopolymerization of vinyl-functional Poly(HEA-MA) or cationic photopolymerization of Poly(EMO-HEA) with pendent oxetane groups. The modified membranes showed enhanced hydrophilicity and underwater oleophobicity than the original membrane. Moreover, the coating (PAN / HEA(C5)) by cationic photopolymerization exhibited lower shrinkage, smoother surface, and more excellent antifouling performance than that by radical photopolymerization. After bovine albumin fouling-cleaning cycles, the flux recovery rate (FRR) of the original membrane was only 68.6 %, while the FRR of PAN / HEA(C5) was as high as 98.0 %. Furthermore, it showed superior long-term operational stability, proving the stability of the coating formed by cationic photopolymerization.

Dimerized small molecule donor enables efficient ternary organic solar cells

Ternary organic solar cells (OSCs) are the feasible and efficient strategy to achieve the high-performance OSCs. It is of great significance to develop a superior third component candidate for constructing efficient ternary OSCs. In this work, we intelligently designed and synthesized a dimerized small molecule donor by connecting two asymmetric small molecule donors with the vinyl group, which is named DSMD-βV. This innovative oligomeric molecule DSMD-βV not only exhibits the complementary absorption and the cascade energy level arrangement with PM6 and BTP-eC9, but also regulates the phase separation micromorphology based on PM6:BTP-eC9. Consequently, PM6:DSMD-βV:BTP-eC9 based ternary device exhibits the improved exciton dissociation, charge transport and decreased recombination, thus achieving a superior power conversion efficiency (PCE) of 18.26 %, surpassing PM6:BTP-eC9 based binary (17.63 %). This work indicates that the dimerized small molecule donor is able to become a promising third component candidate, which also opens up a unique idea for the construction of efficient ternary organic solar cells.

Energetics of the OH radical H-abstraction reactions from simple aldehydes and their geminal diol forms.

Carbonyl compounds, especially aldehydes, emitted to the atmosphere, may suffer hydration in aerosols or water droplets in clouds. At the same time, they can react with hydroxyl radicals which may add or abstract hydrogen atoms from these species. The interplay between hydration and hydrogen abstraction is studied using density functional and quantum composite theoretical methods, both in the gas phase and in simulated bulk water. The H-abstraction from the aldehydic and geminal diol forms of formaldehyde, acetaldehyde, glycolaldehyde, glyoxal, methylglyoxal, and acrolein is studied to determine whether the substituent has any noticeable effect in the preference for the abstraction of one form or another. It is found that abstraction of the H-atom adjacent to the carbonyl group gives a more stable radical than same abstraction from the geminal diol in the case of formaldehyde, acetaldehyde, and glycolaldehyde. The presence of a delocalizing group in the Cα (a carbonyl group in glyoxal and methylglyoxal, and a vinyl group in acrolein), reverts this trend, and now the abstraction of the H-atom from the geminal diol gives more stable radicals. A further study was conducted abstracting hydrogen atoms from the other different positions in the species considered, both in the aldehydic and geminal diol forms. Only in the case of glycolaldehyde, the radical formed by H-abstraction from the -CH2OH group is more stable than any of the other radical species. Abstraction of the hydrogen atom in one of the hydroxyl groups in the geminal diol is equivalent to the addition of the •OH radical to the aldehyde. It leads, in some cases, to decomposition into a smaller radical and a neutral molecule. In these cases, some interesting theoretical differences are observed between the results in gas phase and (simulated) bulk solvent, as well as with respect to the method of calculation chosen. DFT (M06-2X, B2PLYP, PW6B95), CCSD(T), and composite (CBS-QB3, jun-ChS, SCVECV-f12) methods using Dunning basis sets and extrapolation to the CBS limit were used to study the energetics of closed shell aldehydes in their keto and geminal-diol forms, as well as the radical derived from them by hydrogen abstraction. Both gas phase and simulated bulk solvent calculations were performed, in the last case using the Polarizable Continuum Model.

The Vinyl Group: Small but Mighty – Transition Metal Catalyzed and Non‐Catalyzed Vinylation Reactions

AbstractTransition metal catalysis allows for the efficient and selective introduction of vinyl moieties onto organic molecules and offers a versatile approach to synthesizing complex organic molecules. Nonetheless, few transition‐metal free vinylation reactions have also been reported, exhibiting exceptional functional group tolerance and circumventing selectivity issues. This review provides an overview of carbon, nitrogen and oxygen vinylation, presenting innovative strategies and key advancements in the field. Hence, it will serve as a valuable resource for organic chemists who are interested in the synthesis of vinyl‐containing compounds. By understanding the diverse strategies involved in vinylation, readers will gain insights into harnessing this powerful synthetic methodology for the efficient construction of carbon‐carbon and carbon‐heteroatom bonds.

Effect of CO binding to P450 BM3 F393 mutants on electron density distribution in the heme cofactor

Resonance Raman spectroscopy has been performed on a set of cytochrome P450 BM3 heme domains in which mutation of the highly conserved Phe393 induces significant variation in heme iron reduction potential. In previous work [Chen, Z., Ost, T.W.B., and Schelvis, J.P.M. (2004) Biochemistry 43, 1798–1808], a correlation between heme vinyl conformation and the heme iron reduction potential indicated a steric control by the protein over the distribution of electron density in the reduced heme cofactor. The current study aims to monitor changes in electron density on the ferrous heme cofactor following CO binding. In addition, ferric-NO complexes have been studied to investigate potential changes to the proximal Cys400 thiolate. We find that binding of CO to the ferrous heme domains results in a reorientation of the vinyl groups to a largely out-of-plane conformation, the extent of which correlates with the size of the residue at position 393. We conclude that FeII dπ back bonding to the CO ligand largely takes away the need for conjugation of the vinyl groups with the porphyrin ring to accommodate FeII dπ back bonding to the porphyrin ligand. The ferrous-CO and ferric-NO data are consistent with a small decrease in σ-electron donation from the proximal Cys400 thiolate in the F393A mutant and, to a lesser extent, the F393H mutant, potentially due to a small increase in hydrogen bonding to the proximal ligand. Phe393 seems strategically placed to preserve robust σ-electron donation to the heme iron and to fine-tune its electron density by limiting vinyl group rotation.

Visible light-driven organocatalyzed radical ring-opening polymerization of Bicyclo[1.1.0]butanes

Radical ring-opening polymerization (rROP) offers an essentially practical strategy to introduce a broad scope of functional groups in the polymer backbone. While suitable cyclic monomers mostly possess a vinyl group to facilitate the radical addition step, we herein present an efficient rROP of highly strained bicyclo[1.1.0]butane (BCB)-derived monomers through radical addition to bridge σ-carbon–carbon bond by photoinduced electron/energy transfer reversible addition−fragmentation chain transfer (PET-RAFT) polymerization technique, producing poly(BCBs) with relatively predictable molecular wight and low to moderate dispersity. Spatiotemporal control over the polymer chain-growth was achieved and high chain-end fidelity was imparted to access intriguing random and block copolymers with complex structures.

Strategic design of magnetic ionic covalent organic frameworks incorporating amino acid ionic liquids for enhanced selectivity adsorption of benzimidazoles

Advancing the frontier of material design, our innovative magnetic ionic covalent organic framework (MiCOF) masterfully overcomes traditional barriers in selective adsorption, pioneering new functionalities and surface engineering techniques to effectively target and mitigate the impacts of benzimidazoles (BZDs). In previous studies, the idea of designing magnetic nanomaterials through theoretical screening of ionic liquids has been successfully proposed. This work proposed a theoretical and practical design for MiCOFs, aimed at providing a sensitive, selective, rapid, and straightforward method for analyzing trace substances in complex biological matrices. In a gentle one-pot process, the surface of Fe3O4 was coated with covalent organic frameworks (COFs) layer, followed by the modification with amino acid ionic liquid (AAIL) through covalent radical polymerization, facilitated by the abundant unsaturated vinyl groups present. This resulted in MiCOFs (Fe3O4@COF-AAIL) with a stable structure. Compared to unmodified Fe3O4@COF, Fe3O4@COF-AAIL exhibited excellent adsorption selectivity for BZDs. This enhanced selectivity is primarily due to the strong hydrogen bonds and π-π interactions between AAIL and BZDs, aligning well with COSMO-RS theoretical screening predictions. The development of magnetic dispersive solid-phase extraction (MDSPE) enabled rapid processing of BZDs in plasma with low matrix effects (0.9–1.3). This study not only validates a robust framework for the selective separation of trace contaminants in complex biological matrices but also advances the design and application of MiCOFs, setting a new paradigm in material science that could transform the design of novel materials for specific tasks.

Laser assisted embedding of Pd10Cu bimetals in ZIF-8 enabling highly selective hydrogenation of C = C in π-bond conjugation

Selective hydrogenation of vinyl groups (C = C) and carbonyl groups (C = O) is of significance to effectively convert low-value organic compounds into high-value target chemicals, while a challenge remains on the hydrogenation of C = C bond that is in π-bond conjugation with the C = O bond. Herein, we address this challenge based on a synergetic modulation strategy on electronic structure and adsorption configurations to achieve a highly selective hydrogenation of the C = C bond, achieved by laser-assisted embedding of PdxCu bimetals in the ZIF-8 bulk phase (x represents the Pd/Cu molar ratio in PdCu nanoparticles). It is revealed that laser assisted synthesis of PdxCu bimetals not only inhibits the hydrogenation of C = O and promotes the hydrogenation of C = C, but also results in an arched absorption configuration for substrate molecules that facilitates the selective hydrogenation of vinyl groups. Exemplified by cinnamaldehyde (CAL), the present work achieves 98.03 % conversion of CAL and 100 % selectivity of the hydrocinnamaldehyde (HCAL) (70 °C, 1 MPa H2, 1 h), indicating the potential of laser-matter interaction to tackle the trade-off between conversion efficiency and selectivity in thermal catalysis.

Double polymerization synergy to sharpen structural toughness of melamine resin foam

Melamine resin foam (Mfoam) is a porous heat-cured amino resin material with excellent flame retardancy, thermal insulation, and noise reduction capabilities. However, some fatal shortcomings like easy brittle breakage, easy powderization and poor toughness directly limit its wide application and further development. In this paper, hydroxypropyl acrylate (HPA) was used to participate in the synthesis of melamine resin oligomers (Moli) in order to link the vinyl group to molecular skeleton. As a result, both vinyl and hydroxymethyl active groups are present in Moli which provide Moli with the ability to perform free radical polymerization reaction and polycondensation polymerization reaction, named double polymerization reaction (DPR), and produce synergistic effects to form a structurally toughened melamine resin foam (TMfoam). The research shows that the scheme can effectively solve the problems of brittle breakage and easy powderization of Mfoam. And under apparent density (Ad) of 40 ± 2 kg/m3, the prepared TMfoam has good toughness, with the bending strength of 405.2 kPa, the compression strength of 352.5 kPa, and the pulverization rate of 1.18 %. Meanwhile, the combustion grade of the TMfoam can reach to B1 grade, and the thermal conductivity is 0.0328 W/(m·K). Also the absorption coefficient of TMfoam can reach up to 0.92 under frequency of 3045 Hz. All the facts indicate that the DPR showed good synergistic effect during the forming and setting stages from Moli to TMfoam. At the same time, the bubble chamber of TMfoam changes from metastable state to stable state, and its strength and toughness are significantly improved in step. This research has great and practical significance for expanding the wide application of Mfoam type materials.

Towards the preparation of sustainable superplasticizers for geopolymeric pastes via radiation-induced grafting of sulfonic group-bearing monomers onto corn starch

To address escalating environmental and sustainability concerns of petroleum-based superplasticizers (SPs), this work aims to develop sustainable and eco-friendly starch-based SPs using gamma radiation for maintaining the desired workability of geopolymeric pastes. Specifically, two green SPs were prepared from starch via radiation-induced grafting of two sulfonic group-bearing monomers, namely 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and 4-styrene sulfonic acid sodium salt (Na4SS). The grafting reaction was improved by initial modification of starch with glycidyl methacrylate to insert vinyl groups into the starch backbone. The modified starch samples were characterized by a variety of analytical techniques such as FTIR, 1H NMR, EDX, SLS, and viscometry. The prepared SPs exhibited high stability in aqueous 5 % NaOH. The effect of the prepared SPs on the fresh properties of GGBFS/MK geopolymer was studied using the mini slump test, zeta potential, adsorption capacity, and setting time. They significantly improved the paste flowability and dispersion compared to the control. Notably, the aromatic Na4SS-grafted starch displayed a comparable enhancement to the commercial PNS, while outperforming the aliphatic AMPS-grafted sample. This emphasizes the potential of these green SPs to address the challenges posed by the petroleum-based SPs and maximize the benefit of using starch as a green renewable resource.

Synthesis of N-vinylcarbazole from acetylene by a continuous high-pressure liquid-phase process with inherent safety

In this study, a continuous high-pressure liquid-phase acetylene microreaction process is rationally designed and successfully realized by employing the strategy of decoupling the acetylene dissolution and successive reaction. As the acetylene reaction is operated in a pure liquid phase with high acetylene concentration, the safety and efficiency of the acetylene conversion process are greatly improved. As a result, N-vinylcarbazole (NVC) is continuously synthesized from dissolved acetylene at 165 °C and 4.5 MPa. Compared to the conventional batch process, the reaction time is reduced to 5–20 min from 5 to 6 h, the amount of catalyst is reduced by 14.8 times, and the specific activity (g carbazole /g KOH /min) is increased by 220 times. To further increase the yield of NVC, 4-tert-butylcatechol (TBC) is added to the feedstock as a polymerization inhibitor, which improves the yield of NVC to 88 %. Several other vinyl compounds, in addition to NVC, are also continuously synthesized from acetylene using this method, which suggests that the process decoupling reaction strategy is widely applicable to acetylene-involved reactions.

Chitosan-based hydrogels: Influence of crosslinking strategy on rheological properties

The effect of two crosslink strategies on the preparation of chitosan-based covalent hydrogels was investigated employing the widely used thiol-ene reaction. This versatile “click” chemistry can be activated either photochemically or thermochemically. Initially, well-purified chitosan (CS, DA ∼4 %, Mw ∼580 kg mol−1) was separately functionalized with vinyl (CS-ene) or thiol (CS-SH) groups in aqueous media. Subsequently, two strategies were compared where thiol-ene reaction occurs respectively between: (S1) modified chitosans CS-ene and CS-SH, in a polymer – polymer strategy, and (S2) CS-ene and di(ethylene glycol) dithiol (dEG-(SH)2), in a polymer – molecule strategy.Both crosslinking strategies were evaluated through rheological measurements, starting with entangled chitosan solutions. The difference in diffusion of functional groups, whether attached to polymer chains or to free molecules, leads to faster gelation kinetics with S2. Consequently, stronger gels were obtained with S2, where the modulus was connected with the degree of functionalization, while S1 produced weaker gels closer to the percolation point, where crosslinked density was associated with the entanglement number derived from the initial concentration. Nevertheless, networks formed by both strategies were homogenous with minimal dissipative contributions to their rheological properties, indicating that structural defects are negligible.

Titanium catalyzed [2σ + 2π] cycloaddition of bicyclo[1.1.0]-butanes with 1,3-dienes for efficient synthesis of stilbene bioisosteres

Natural stilbenes have shown significant potential in the prevention and treatment of diseases due to their diverse pharmacological activities. Here we present a mild and effective Ti-catalyzed intermolecular radical-relay [2σ + 2π] cycloaddition of bicyclo[1.1.0]-butanes and 1,3-dienes. This transformation enables the synthesis of bicyclo[2.1.1]hexane (BCH) scaffolds containing aryl vinyl groups with excellent regio- and trans-selectivity and broad functional group tolerance, thus offering rapid access to structurally diverse stilbene bioisosteres.