Vinylation Reaction Research Articles

Sequence-Controlled Electrochemical Immobilization of Catalyst-Photosensitizer Oligomers for Tuning Photoelectrochemical Behaviors.

Immobilizing catalysts and photosensitizers on an electrode surface is crucial in interfacial energy conversion. However, their combination for optimizing catalytic performance is an unpredictable challenge. Herein, we report that catalyst and photosensitizer monomers are selectively grafted one-by-one addition onto the electrode surface by interfacial electrosynthesis to achieve composition and sequence-controlled oligomer photoelectrocatalytic monolayers. This electrosynthesis relies on the oxidative coupling reaction of carbazole and the reductive coupling reaction of vinyl on the catalyst and photosensitizer monomers, and it initiates on self-assembled monolayers and propagates with alternating positive and negative potentials. Each addition and completion of the target monomer can be quantitatively identified and monitored by optical and electrical responses and their linear coefficients as a function of reaction steps. The resulting composition and sequence-controlled monolayers exhibit tuning electrocatalytic behaviors including water splitting and CO2 reduction, indicating an efficient way to optimize the electro- and photocatalytic functions and performance of molecular materials.

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.

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.

Synthesis and cytotoxic evaluation of heterocyclic compounds by vinylic substitution of ketene dithioacetals.

N-heterocyclic compounds are important molecular scaffolds in the search for new drugs, since most drugs contain heterocyclic moieties in their molecular structure, and some of these classes of heterocycles are able to provide ligands for two or more biological targets. Ketene dithioacetals are important building blocks in organic synthesis and are widely used in the synthesis of N-heterocyclic compounds. In this work, we used double vinylic substitution reactions on ketene dithioacetals to synthesize a small library of heterocyclic derivatives and evaluated their cytotoxic activity in breast and ovarian cancer cells, identifying two benzoxazoles with good potency and selectivity. In silico predictions indicate that the two most active derivatives exhibit physicochemical properties within the range of drug-like compounds and showed potential to interact with HDAC8 and ERK1 cancer-related targets.

A novel high reactive initiator system of vinyl‐substituted hydridopolycarbosilane (VHPCS) for lower curing temperature and higher ceramic yields

AbstractVinyl‐substituted hydridopolycarbosilane (VHPCS) is widely studied for its low viscosity, abundance of active functional groups, rapid curing, and high ceramic yield. The curing reactions mainly involve the free radical polymerization of vinyl and hydrosilylation reactions, but these reactions typically require high temperatures such as 160–250°C. The curing behavior of VHPCS‐17 with a tert‐butyl peroxybenzoate/Nickel acetylacetonate (TBPB/NIAA) system is investigated using differential scanning calorimetry and in situ Fourier transform infrared. The properties of VHPCS‐17 with different initiator systems and VHPCS with different vinyl contents (under TBPB/NIAA system) are studied using thermogravimetric analysis and x‐ray diffraction. The results demonstrate that the TBPB/NIAA system can facilitate the free radical polymerization of vinyl; moreover, this system decreases the peak temperature of the curing reaction from 251 to 141°C and increases the ceramic yield from 80.49% to 89.88%. The ceramic yield of cured VHPCS increases gradually, reaching 89.88% when the vinyl content is 17%. The grain size of β‐SiC decreases continuously with the increase in vinyl content, while the high‐temperature oxidation‐resistant properties of SiC ceramics obtained from different VHPCSs are not negatively affected.

Boosting Sulfonylation Reactions between Vinyl Triflates and Alkenes toward β-Ketosulfones Using Aqueous Sulfurous Acid

AbstractWe successfully synthesized trifluoromethylated β-ketosulfones via the reaction of vinyl triflates with alkenes employing aqueous sulfurous acid as an external source of SO2. The PhSSPh/photoinitiated reaction with vinyl triflates that contain electron-deficient groups or halogens did not show any base-related effects, whereas the radical reaction was impeded in the absence of a base in the case of vinyl triflates generated from phenylacetylenes.

Synthesis of Styrenes and E‐Stilbenes by Palladium‐Catalyzed Vinylation of Aryl Iodides with 1,2‐Dibromoethane

AbstractThe Pd‐catalyzed vinylation reactions of aryl iodides using 1,2‐dibromoethane is developed for the synthesis of styrenes and stilbenes. In these reactions, vinyl bromide is generated from 1,2‐dibromoethane and then undergoes reductive cross‐coupling with aryl iodides, affording styrene products. Under slightly modified reaction conditions, styrenes can continue reacting with vinyl bromide to form E‐stilbenes, which provides a one‐pot synthetic method for stilbenes. Alcohols, including iso‐propanol and methanol, are employed as the reductant in these reductive cross‐coupling reactions.

Some Aspects of α-(Acyloxy)alkyl Radicals in Organic Synthesis.

The preparation and use of α-(acyloxy)alkyl xanthates to generate and capture α-(acyloxy)alkyl radicals is briefly reviewed. Their inter- and intramolecular additions to both activated and unactivated, electronically unbiased, alkenes, and to (hetero)aromatic rings, as well as their radical allylation and vinylation reactions are described. Application to the total synthesis of two 4-hydroxytetralone natural products is also presented.

Catalyst-Assisted Selective Vinylation and Methylallylation of a Quaternary Carbon Center Using tert-Butyl Acetate.

The In(OTf)3-catalyzed α-vinylation of various hydroxy-functionalized quaternary carbon centers using in situ generated isobutylene from tert-butyl acetate is presented as a novel synthetic methodology. Moreover, tert-butyl acetate is a nonflammable feed stock and is a readily available source for the in situ production of vinyl substituents, as demonstrated by the vinylation reaction with quaternary hydroxy/methoxy compounds. Moreover, an excellent selectivity for methylallylation over vinylation was obtained with Ni(OTf)2 as a catalyst. In the case of peroxyoxindole, methylallyl-functionalized 1,4-benzoxazin-3-one derivatives were formed through the sequential rearrangement of peroxyoxindole followed by the nucleophilic attack by isobutylene. The detailed mechanism for this reaction and rationalization for the selectivity are provided using kinetics and density functional theory studies.

Synthesis of Vinyl Esters of Fruit Acids under High Pressure

This article describes a method for the synthesis of vinyl esters from fruit acids: malic, tartaric, citric and acetylene, as well as the results of a spectrophotometric analysis of the obtained compounds. Process conditions, product yields, and physicochemical properties of the resulting vinyl esters are given. The homogeneous catalytic reaction of vinylation of malic, tartaric and citric acids with acetylene has been studied and the formation of the corresponding vinyl esters has been proven. The mechanisms of vinylation reactions in the presence of acetylene are proposed. In the synthesis of vinyl ethers, the effect of pressure, temperature, and reaction time on the product yield was established.

Paving the way to the synthesis of PAHs in dark molecular clouds: The formation of cyclopentadienyl radical (c-C5H5)

Context. The interest of astrophysicists and astrochemists in studying polycyclic aromatic hydrocarbons (PAHs) has grown since their assignment to previously unidentified IR emission bands of dust grains. Although observations show that PAHs are present in the interstellar medium (ISM), there is still no consensus about their formation. PAH formation has been studied following two approaches: bottom-up (i.e. through the association of smaller hydrocarbons) and top-down (via the photo-dissociation or hydrogenation of larger-structures). The recent detection of simple aromatic rings in the TMC-1 molecular cloud seems to suggest the bottom-up scenario is favoured. Aims. We study the reaction between the propargyl (C3H3) radical and the vinyl radical (C2H3) under interstellar conditions, providing new kinetic parameters for the formation of PAH precursors. Methods. We used high-level quantum-chemical calculations to describe the reaction mechanism between these two radicals. We calculated the rate constant of the individual product channels in the temperature range 10–400 K and at 1 × 10−7 atm by solving the one-dimensional master equation to quantitatively understand whether this reaction is viable in the ISM. Results. Our results show that this reaction is likely to occur even in the low-density (~104 cm−3) and low-temperature (~10 K) conditions of molecular dark clouds. The main product is the cyclopentadienyl radical (C5H5). The unsaturated open-chain hydrocarbon C5H5 in the trans (trans-C5H5) and cis conformations (cis-C5H5) are also formed, but to a lesser extent. Conclusions. Our results show that the reaction of vinyl radical with propargyl radical is efficient under interstellar conditions and yields the cyclopentadienyl radical, which could be an important precursor for the formation of more complex polycyclic hydrocarbons (e.g. indene) and simple PAHs (e.g. naphthalene) in molecular dark clouds.

Fine Tuning of Quantum Dots Photocatalysts for the Synthesis of Tropane Alkaloid Skeletons.

Several types of Quantum Dots (QDs) (CdS, CdSe and InP, as well as core-shell QDs such as type I InP-ZnS, quasi type-II CdSe-CdS and inverted type-I CdS-CdSe) were considered for generating α-aminoalkyl free radicals. The feasibility of the oxidation of the N-aryl amines and the generation of the desired radical was evidenced experimentally by quenching of the photoluminescence of the QDs and by testing a vinylation reaction using an alkenylsulfone radical trap. The QDs were tested in a radical [3+3]-annulation reaction giving access to tropane skeletons and that requires the completion of two consecutive catalytic cycles. Several QDs such as CdS core, CdSe core and inverted type I CdS-CdSe core-shell proved to be efficient photocatalysts for this reaction. Interestingly, the addition of a second shorter chain ligand to the QDs appeared to be essential to complete the second catalytic cycle and to obtain the desired bicyclic tropane derivatives. Finally, the scope of the [3+3]-annulation reaction was explored for the best performing QDs and isolated yields that compare well with classical iridium photocatalysis were obtained.

Transition Metal‐Catalyzed Dearomative Vinylation of Electron Rich Benzenes, Naphthalenes and Indoles with Alkynes

AbstractDearomatization reactions are among the most efficient chemical processes, combining atom economy, stereospecificity and the ability to generate molecular complexity in a single step. Dearomative vinylation reactions provide a synthetic connection between readily available, simple aromatic starting materials and more unsaturated alkynes. The last decade has witnessed a steady increase in the development of transition metal‐catalyzed dearomative vinylation methods of electron rich aromatic compounds with alkynes, providing new synthetic approaches to high‐value building blocks and natural products. This review aims to serve as a comprehensive reference for work in transition metal‐catalyzed dearomative vinylation reactions of electron rich aromatic compounds with alkynes.magnified image

Synthesis of hyperbranched polyarylethenes by consecutive C–H vinylation reactions

Polyarylethenes are obtained by electrophilic C–H vinylation reactions of tetraphenylethene with a triazene. The hyperbranched polymers display size-dependent emission and unusual ratiometric AIE behavior.

Numerical Simulation of Gaseous Detonation Performance and Wall Reflection Effect of Acetylene-Rich Fuel

The efficient utilization of energy in rich fuel detonation processes and the effective control method of soot are important topics in combustion research. In this paper, we numerically study the detonation wave behavior of acetylene–air systems in rich fuel condition by using a reduced reaction mechanism. The non-stiff terms of the governing equations are solved explicitly using the gas kinetic scheme, and the stiff terms are solved implicitly. Our results show that the acetylene pyrolysis is the dominant reaction process. The oxidation reaction is exploited to initiate the reaction induction process, providing the required energy to overcome the potential energy barrier. The secondary detonation structure is due to the stable interaction of the transverse waves and the combined action of the vinyl reaction system, thus effectively improve the energy release rate and providing a powerful solution for the fuel-rich high-energy release of advanced heat engines. The area of the unreacted pocket increases with the acetylene concentration, resulting in an irregular wave-front and detonation cell. The reflected shock wave impacting on the wall induces the secondary reaction of the detonation products. The concentration of polycyclic aromatic hydrocarbons decreases significantly and regenerates near the wall. Our approach provides an effective tool for controlling detonation soot and the preparation of carbon particles.

Palladium-Catalyzed Regioselective [5 + 1] Annulation of Vinyl Aziridines/Epoxides with ClCF2COONa

Palladium-catalyzed regioselective [5 + 1] annulation reactions of vinyl aziridines/epoxides with ClCF2COONa have been developed. Significantly, vinyl aziridines/epoxides act as heteroatom-containing five-atom synthons, and commercially available and cheap ClCF2COONa acts as the source of carbonyl serving as a difluorocarbene precursor. This protocol provides an efficient and practical method for the synthesis of δ-lactams and δ-lactones in good yields.

A green synthetic toolbox from organocatalytic alternating copolymerization of renewable epoxides and dihydrocoumarin

AbstractThe ring‐opening alternating copolymerization (ROAC) of biorenewable glycidyl ethers with 3,4‐dihydrocoumarin (DHC) was achieved by using metal‐free Lewis pair as catalyst. This mild process provided access to renewable polyesters with perfectly alternating structures and functional groups fidelity. Remarkably, we observed highly regioregular arrangement of substituents along with poly(phenol ether‐alt‐ester) backbone. A one‐step strategy to block copolymer could also be realized by terpolymerization of DHC, epoxides with cyclic anhydrides via pre‐rate‐determining selectivity. Post‐polymerization modification of the resultant polyesters was further performed by thiol‐ene click reaction of vinyl, Diels–Alder reaction of furyl, cleavage reaction of benzyl ethers and tetrazine click reaction. By incorporating two different pendant functional groups into a copolymer, combinatorial and selective functionalization was achieved for introducing additional functionality, giving a route to highly modifiable polyesters. Therefore, this work provides a paradigm for designing functional and regioregular polyesters as a green synthetic toolbox derived from organocatalysis and renewable feedstocks.

Nickel-Catalyzed Carbonylative Synthesis of α,β-Unsaturated Thioesters from Vinyl Triflates and Arylsulfonyl Chlorides.

A straightforward and efficient synthesis of α,β-unsaturated thioesters has been developed via a nickel-catalyzed thiocarbonylation reaction of vinyl triflates with arylsulfonyl chlorides. With Mo(CO)6 as both CO source and reductant, a variety of α,β-unsaturated thioesters were obtained in moderate to good yields with very good functional group compatibility. It is noteworthy that the present method is the first example on nickel-catalyzed carbonylative synthesis of α,β-unsaturated thioesters by using arylsulfonyl chlorides as the coupling partner.

Front Cover Picture: Use of Iridium‐Catalyzed Transfer Vinylation for the Synthesis of Bio‐Based (bis)‐Vinyl Ethers (Adv. Synth. Catal. 7/2022)

The front cover picture depicts bio-based bis-vinyl ether structures which were synthesized through a catalytic transfer vinylation reaction, where a cationic iridium complex was used as the catalyst, sodium acetate as the base, vinyl acetate as the vinylating agent, and 2-MeTHF as a green solvent. Many of the herein described (bis)-vinyl ethers are reported for the first time and bear high potential as an integral part in adhesives, coatings, or UV-inks. Details can be found in the research article by de Vries and co-workers (B. Spiegelberg, H. Jiao, R. Grauke, C. Kubis, A. Spannenberg, A. Brandt, A. Taden, H. Beck, S. Tin, J. G. de Vries, Adv. Synth. Catal. 2022, 364, XXXX-YYYY; DOI: 10.1002/adsc.202101348)

Ti-Catalyzed Reductive Dehydroxylative Vinylation of Tertiary Alcohols

Metal-catalyzed direct deoxygenative C(sp3)–C(sp2) coupling of alcohols is synthetically appealing, but it remains a particular challenge for the synthetic community. Herein, we demonstrate a radical dehydroxylative vinylation reaction of tertiary alcohols by Ti catalysis and, thus, establish a method for the construction of vinylated all-carbon quaternary centers. The reaction proceeds under mild conditions and tolerates various functionalities, including Ar–Bpin, Ar–SiMe3, alkyl chloride, phenol, nitrile, ester, furan, and thiophene. The reaction works with various vinyl halides, including fluorides, chlorides, bromides, and iodides. The use of a mixture of trans- and cis-haloalkenes gives the same trans products. The selectivity profiles were investigated among the vinyl and aryl electrophiles and among the different classes of alcohols.