Applications In Organic Synthesis Research Articles

Recent Advances of Plastic Waste‐Derived Carbon Materials for Energy Storage, Environmental Remediation and Organic Synthesis Applications

AbstractThe escalating severity of plastic waste's impact on the ecological environment and human health emphasize the crucial importance of developing resource‐conserving disposal technologies for sustainable development. Carbon‐based materials possess extensive functional applications across various fields, however, their high production costs and heavy reliance on fossil fuels pose challenges. Plastic wastes serve as ideal precursors for the green and sustainable production of carbon‐based functional materials due to high carbon content and low‐cost. This review provides a comprehensive summary of recent research progress on plastic waste‐derived carbon materials (PWCMs) including primary strategies for constructing PWCMs and their current functional applications in energy storage, environmental remediation and organic synthesis.

Gold‐Catalyzed Heck and Suzuki‐Type Reactions: Challenges and Recent Advances

AbstractTransition metal‐catalyzed Suzuki and Heck reactions are two of the most common carbon‐carbon bond formation reactions. Gold, unlike other transition metals (Pd, Ni, and Cu), offers unique reactivity profiles, and has emerged as an efficient tool in the field of synthetic organic chemistry. This mini‐review focused on the recent work in gold‐catalyzed Heck and Suzuki‐type reactions, especially by photocatalysts or ligand design, which show reactivities and features distinct from other transition metals. These discoveries will further facilitate the development of gold redox catalysis as well as applications in organic synthesis, biochemistry, and medicinal chemistry.

Access to Vinyl gem-Difluorinated Cyclopropanes via Photopromoted Palladium-Catalyzed Heck Reaction.

A photopromoted Pd-catalyzed Heck reaction of gem-difluorocyclopropyl bromides (DFCBs) with styrenes to deliver vinyl gem-difluorinated cyclopropanes (VDFCs) under mild conditions has been developed. The reaction demonstrates good functional group compatibility while providing high E/Z ratio of the products. Furthermore, the desired VDFCs can be easily transformed into fluorinated cyclic/acyclic architectures, which may broaden its applications in organic synthesis.

Oxidation of Geraniol on Vermiculite—The Influence of Selected Parameters on the Oxidation Process

Geraniol is a compound belonging to the group of monoterpenes that finds many applications in organic syntheses, medicine and cosmetics. The following properties of geraniol and its derivatives are of particular interest in medicine: its anti-inflammatory, antioxidant, antimicrobial and anticancer effects. The geraniol oxidation process was carried out using a mineral of natural origin—vermiculite. Vermiculite is a catalyst that perfectly fits into modern trends in the organic industry, where the aim is to use cheap, renewable and relatively easily available catalytic materials (vermiculite is found on continents including Africa, North America, South America, Australia and Asia). Preliminary studies on the oxidation process of geraniol on vermiculite was carried out in a glass apparatus using molecular oxygen supplied by means of a bubbler and magnetic stirrer with a heating function. During the oxidation process of geraniol on vermiculite, the influence of the following parameters was examined: the temperature, amount of catalyst and reaction time. The main parameters of the process, on the basis of which the most favorable process conditions were selected, were the selectivity of the transformation to 2,3-epoxygeraniol, citral and 2,3-epoxycitral, and the conversion of geraniol. The composition of the post-reaction mixtures was determined qualitatively and quantitatively using the gas chromatography method. In addition, vermiculite was subjected to instrumental tests, such as XRD, SEM, EDX, FTIR and UV-VIS. Moreover, the specific surface area, pore volume and pore volume distribution were estimated on the basis of N2 sorption at −196 °C and also the acid-site concentration in vermiculite was established.

Synthesis of Diaryl Diselenides and Ditellurides via Bromide-Catalyzed C–Se/C–Te Bond Formation Using Se/Te Powder and Boronic Acid

AbstractDiaryl diselenides and diaryl ditellurides are commonly employed as selenyl or telluryl sources, and they have a wide range of applications in organic synthesis. Herein, various diaryl diselenides/ditellurides are furnished in moderate to excellent yields under metal-free conditions. This method features high efficiency, good functional group tolerance, straightforward operation, and easy scale-up (running in 4 mmol-scale for most cases). Mechanistic studies indicate that this reaction may proceed via a radical pathway. Significantly, the correct matching of Br– and dimethyl sulfoxide under an air atmosphere is critical to this transformation.

Exploring the Role of Titanate Perovskites in the Oxidation of Amines to Imines via Photocatalysis.

Considering that structural differences could affect the photocatalytic efficiency of titanate perovskites, cubic SrTiO3 (STO) and tetragonal CaTiO3 (CTO) were synthesised as models to elucidate the structure-activity relationship. STO and CTO materials were produced through hydrothermal approaches, adjusting parameters such as temperature and pressure to optimise material purity. Among the perovskite photocatalysts, two stand out for their exceptional photocatalytic capacity and crystalline purity: CaTiO3, prepared at 180 ºC for 36 h, and SrTiO3, synthesised at 200 ºC for 24 h. Notably, we explore the selective ability of these materials for the photocatalytic oxidative self-coupling of benzylamine (BZA) to produce N-benzylidenebenzylamine (BZI), with CaTiO3 emerging as the most efficient catalyst for this reaction. The CTO material prepared at 180 ºC for 36 h (CTO180T-36) achieved a peak BZI production of 0.5 mM, with a total conversion of BZA after 7 h of irradiation. This study also emphasises the crucial role of reaction conditions and perovskite morphologies in fine-tuning photocatalytic performance. These findings highlight opportunities for developing efficient and selective photocatalytic processes, holding the compromise for applications in organic synthesis and sustainable green chemistry.

Photoredox/Copper-Cocatalyzed Domino Annulation of Oxime Esters and NH4SCN: Access to Fully Substituted 2-Aminothiazoles.

Domino cyclization of oxime esters and NH4SCN facilitated by photoredox and copper cocatalysis has been established. Various structurally diverse fully substituted 2-aminothiazoles have been obtained in good yields at room temperature. It is featured by mild conditions, favorable functional group tolerance, and wide substrate scope. The present reaction is amenable to gram-scale synthesis, which is expected to find potential applications in organic synthesis and drug discovery. A plausible reaction mechanism is proposed.

Short DNAzymes for Efficient Catalysis of "Click" Reactions in Solution and on Surface.

We have systematically investigated and found surprising superior catalytic activities of very short DNAzymes for copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC), both in solution and on surface. As a key reaction of the "click chemistry" class, CuAAC is a highly efficient and specific covalent conjugation tool with demonstrated applications in organic synthesis, bioconjugation, and surface functionalization; however, it requires the presence of the Cu(I) catalyst, which is an unstable species in aqueous solutions. We show here that one ultrashort, 14-nucleotide-truncated fragment of an earlier in vitro selected DNAzyme (CLICK-17) shows a striking and superior catalytic activity toward the in trans CuAAC reaction in solution and on surface in the presence of either Cu(I) or Cu(II), at significantly lowered concentrations. These results obviate the need for long-sequence DNAzymes, selected out of the homogeneous solution phase, for application in complex surface environments.

Heteropoly Acid‐Based Ionic Liquid Catalyzes Cellulose into Levulinic Acid in a Bi‐Phase Solvent System

AbstractLevulinic acid is an important chemical intermediate, which has many applications in organic synthesis, industry, agriculture, and medicine. In this word, three kinds of heteropoly acid based ionic liquids ([IMPS]H2PW12O40、[PyPS] H2PW12O40 [TEAPS] H2PW12O40) were used to catalyze the one‐pot conversion of cellulose to levulinic acid. [IMPS]H2PW12O40 has the highest catalytic activity due to its strong Hammett acidity (H0). In addition, the effect of biphasic solvent systems on the conversion of cellulose to levulinic acid was also studied. The results showed that the GVL/H2O system could effectively promote the conversion of cellulose and increase the yield of levulinic acid. The yield of levulinic acid could reach 52.6% and the conversion rate of cellulose was 91.2% at 180 °C for 180 min under the GVL/H2O volume ratio of 1:1 with [IMPS]H2PW12O40 as a catalyst at 1 Mpa N2 and cellulose as raw material. And [IMPS]H2PW12O40 can be recycled up to five times without significant performance loss. This study provides a promising method for efficiently converting cellulose and other biomass resources to levulinic acid extraction.

Deoxygenation of benzylphenyl sulfones using 1,2-bis(diphenylphosphino)ethane (dppe)/NBS under metal-free conditions

An efficient route for the chemoselective deoxygenation of benzylphenyl sulfones to the corresponding sulfides has been developed using a mixture of 1,2-bis(diphenylphosphino)ethane(dppe) and NBS as an effective promoter. This is the first development on the deoxygenation of diverse benzylphenyl sulfones under metal-free conditions. The mild reaction conditions, formation of the water soluble by-product and tolerance of a wide range of functional groups promote its broad applications in organic synthesis.

Mechanochemistry: A Resurgent Force in Chemical Synthesis

Mechanochemistry, a solvent-free approach that harnesses mechanical energy, is emerging as a transformative technique in modern chemistry. It has emerged from a niche technique to a versatile tool with broad applications. By inducing physical and chemical transformations, it enables the synthesis of complex molecules and nanostructured materials. Recent advancements have extended its applications beyond simple physical transformations to encompass catalytic processes, unlocking new possibilities for selective synthesis and product design. This account delves into the fundamentals of mechanochemistry, its applications in organic synthesis, and also beyond traditional synthetic routes, mechanochemistry offers new avenues for molecular and materials discovery, expanding the scope of accessible chemical space.

Photoinduced Electron Donor Acceptor Complex-Enabled α-C(sp3)-H Alkenylation of Amines.

Allylic amines are prevalent and vital structural components present in many bioactive compounds and natural products. Additionally, they serve as valuable intermediates and building blocks, with wide-ranging applications in organic synthesis. However, direct α-C(sp3)-H alkenylation of feedstock amines, particularly for the preparation of α-alkenylated cyclic amines, has posed a longstanding challenge. Herein, we present a general, mild, operationally simple, and transition-metal-free α-alkenylation of various readily available amines with alkenylborate esters in excellent E/Z - and diastereoselectivities. This method features good compatibility with water and oxygen, broad substrate scope, and excellent functional group tolerance, thereby enabling the late-stage modification of various complex molecules. Mechanistic studies suggest that the formation of a photoactive electron donor-acceptor complex between 2-iodobenzamide and the tetraalkoxyborate anion, which subsequently undergoes photoinduced single electron transfer and intramolecular 1,5-hydrogen atom transfer to generate the crucial α-amino radicals, is the key to success of this chemistry.

Photoinduced Electron Donor Acceptor Complex‐Enabled α‐C(sp3)−H Alkenylation of Amines

AbstractAllylic amines are prevalent and vital structural components present in many bioactive compounds and natural products. Additionally, they serve as valuable intermediates and building blocks, with wide‐ranging applications in organic synthesis. However, direct α‐C(sp3)−H alkenylation of feedstock amines, particularly for the preparation of α‐alkenylated cyclic amines, has posed a longstanding challenge. Herein, we present a general, mild, operationally simple, and transition‐metal‐free α‐alkenylation of various readily available amines with alkenylborate esters in excellent E/Z ‐ and diastereoselectivities. This method features good compatibility with water and oxygen, broad substrate scope, and excellent functional group tolerance, thereby enabling the late‐stage modification of various complex molecules. Mechanistic studies suggest that the formation of a photoactive electron donor‐acceptor complex between 2‐iodobenzamide and the tetraalkoxyborate anion, which subsequently undergoes photoinduced single electron transfer and intramolecular 1,5‐hydrogen atom transfer to generate the crucial α‐amino radicals, is the key to success of this chemistry.

Post‐Functionalization of Organoboranes by Cu‐Catalyzed Azide Alkyne [3+2]‐Cycloaddition Reaction

AbstractThe copper‐catalyzed azide alkyne [3+2]‐cycloaddition (CuAAC) reaction of organoboranes represents an attractive area of research within the field of click chemistry, with diverse applications in organic synthesis, medicinal chemistry, or materials science. Despite the potential issues caused by the copper insertion into the carbon‐boron bond, significant progress has been made to harness the reactivity of organoboron compounds in CuAAC. This review provides an overview of the catalytic methods reported for CuAAC with various organoboranes, discussing the stability of the boron group and highlighting recent advancements in this area.

Emerging Trends for the Direct Synthesis of Dithiocarbamates

Dithiocarbamates are common structural motifs in various bioactive compounds, attracting considerable attention due to their wide‐ranging applications in organic synthesis, material science, agrochemicals, and the pharmaceutical industry. Given the significant bioactivity and extensive applications of dithiocarbamates, the continuous pursuit of their efficient and diverse synthetic methods remains critical and urgent. Direct dithiocarbamation reactions can introduce ‐S‐C(S)NR2 group directly into parent molecules, providing shorter, greener, and more practical pathways for the synthesis of organodithiocarbamates. This article offers a comprehensive overview of the latest advancements in direct dithiocarbamation reactions, categorizing them based on the different sources of the ‐S‐C(S)NR2 group, with a particular emphasis on elucidating substrate scope and reaction mechanisms. Additionally, some synthetic limitations and applications of these methods are discussed. This review aims to provide the latest advancements in this field to both general readers and professional practitioners, inspiring innovative ideas for the synthesis of organosulfur compounds.

C–H/C–H Aromative carbonylation of diarylalkynes enabled palladium-catalyzed by 6-endo-dig carbocyclization

Transition metal-catalyzed cycloaromatization reactions of diarylalkynes offer a swift and versatile approach to synthesizing a wide array of polycyclic aromatic compounds. However, the specific mechanism of Pd-catalyzed C–H/C–H aromative carbonylation of diarylalkynes, particularly those bearing adjacent functional groups, remains a relatively unexplored area. Herein, we present a palladium-catalyzed C–H/C–H aromative carbonylation of diarylalkynes, which proceeds through an exclusive 6-endo-dig carbocyclization pathway, followed by the incorporation of CO to yield carbonyl compounds. This methodology provides a novel and efficient route for generating complex aromatic structures, thus expanding the potential applications in organic synthesis.

An Overview of Hydrogen Production from Renewable Sources and Its Main Applications

AbstractThere is a misconception that sustainability is only related to greenhouse gas emissions into the atmosphere, and that this is the only risk to which the planet is exposed. Sustainability is a multidimensional concept and must advance simoutaneously on several fronts, such as the urgent need to increase energy, clean water, clean air, food, mobility, health, and poverty reduction. All the problems of these multi‐dimensions are aggravated by the continuous growth of the world population, mainly in economic and socio‐environmental issues. However, the biggest challenge is to increase the supply of clean energy from renewable sources, as all other dimensions of sustainability depend on energy supply and policy decisions. The consumption of fossil fuels has supplied the current energy demand by approximately 87 %. Still, there are predictions of depletion, and the effects caused on the environment by the production of greenhouse gases bring significant economic losses. In this review, we will address the most common methods for hydrogen production, as well as its main technological applications in organic synthesis and for energy generation.

"Cation Pool" generated from DMSO and 1,2-dihaloethanes and their application in organic synthesis.

Conventionally, carbenium and onium ions are prepared in the presence of nucleophiles due to their instability and transient nature. The nucleophiles that are unstable or inert to the reaction media cannot be used for reaction with the cationic species to access the desired compounds. To overcome these limitations, developing methods for generating organic cations irreversibly in the absence of nucleophiles is essential. The "cation pool" method developed by Yoshida and co-workers stands out as a reliable strategy to generate and accumulate the reactive cations in solution in the absence of nucleophiles. The cation pool method involves the electrolysis of the substrate in the absence of nucleophiles, usually at low temperature. Moreover, the generation of halogen and chalcogen cations through electrolysis needs extra care because of their low stability. This review covers our effort in generating and accumulating halogen cations as "cation pools", most importantly by simply heating a mixture of dimethyl sulfoxide (DMSO) and 1,2-dihaloethane (DXE, X = Cl, Br, I), and their use in the halogenation reactions. Furthermore, condition-dependent Pummerer-type fragmentations of DMSO-stabilized halogen cations to methyl(methylene)sulfonium ions and chlorodimethylsulfonium ions for synthetic applications are described.

Modular Synthesis of Azines Bearing a Guanidine Core from N-Heterocyclic Carbene (NHC)-Derived Selenoureas and Diazo Reagents.

N-Heterocyclic carbene (NHC)-derived selenoureas comprise a fundamentally important class of NHC derivatives, with key applications in coordination chemistry and the determination of NHC electronic properties. Considering the broad reactivity of chalcogen-containing compounds, it is surprising to note that the use of NHC-derived selenoureas as organic synthons remains essentially unexplored. The present contribution introduces a novel, straightforward transformation leading to azines bearing a guanidine moiety, through the reaction of a wide range of NHC-derived selenoureas with commercially available diazo compounds, in the presence of triphenylphosphine. This transformation offers a new approach to such products, having biological, materials chemistry, and organic synthesis applications. The guanidine-bearing azines are obtained in excellent yields, with all manipulations taking place in air. A reaction mechanism is proposed, based on both experimental mechanistic findings and density functional theory (DFT) calculations. A one-pot, multicomponent transesterification reaction between selenoureas, α-diazoesters, alcohols, and triphenylphosphine was also developed, providing highly functionalized azines.

WITHDRAWN: Gellan gum-cellulose hydrogel incorporating with graphene oxide and magnetic nanoparticles as a novel nanocatalyst for the synthesis of dihydropyrano derivatives

In this project, a highly efficient catalyst with a remarkable yield of over 97 % was developed for the synthesis of dihydropyrano[2,3-c] pyrazole derivatives. A Gellan Gum-Cellulose hydrogel was prepared using Glutaraldehyde as the cross-linker, which served as the matrix for further modifications. Synthesized graphene oxide was then incorporated into the hydrogel structure using a modified Hummers method, enhancing the catalytic properties of the material. To facilitate the separation and recovery of the catalyst, the resulting structure was magnetized, leading to the formation of a magnetic nanocomposite. Even after undergoing four cycles of catalyst recovery, the GG-Cell hydrogel/GO/Fe3O4 nanocomposite retained 90 % of its initial catalytic activity, highlighting its robustness and stability. Detailed physical and chemical analyses were conducted to gain a comprehensive understanding of the synthesized magnetic catalyst, contributing to the advancement of the field of catalysis and holding great potential for various applications in organic synthesis and related fields.