Bis(2-butoxyethyl) Ether-Promoted O2-Mediated Oxidation of Alkyl Aromatics to Ketones under Clean Conditions

Conventional oxidation processes for alkyl aromatics to ketones employ oxidants that tend to generate harmful byproducts and cause severe equipment corrosion, ultimately creating critical environmental problems. Thus, in this study, a practical, efficient, and green method was developed for the synthesis of aromatic ketones by applying a bis(2-butoxyethyl) ether/O2 system under external catalyst-, additive-, and base-free conditions. This O2-mediated oxidation system can tolerate various functional groups and is suitable for large-scale synthesis. Diverse target ketones were prepared under clean conditions in moderate-to-high yields. The late-stage functionalization of drug derivatives with the corresponding ketones and one-pot sequential chemical conversions to ketone downstream products further broaden the application prospects of this approach.

Energy-efficient chemical recycling of CFRP and analysis of the interfacial shear strength on recovered carbon fiber

Here we report a novel chemical recycling of carbon fiber-reinforced plastic (CFRP) using meta-chloroperoxybenzoic acid (mCPBA) as the representative oxidizing agent. The optimal decomposition conditions for the epoxy (EP) resin in CFRP were investigated by varying mCPBA concentration and reaction time. The CFRP decomposed completely within 6 h using a 1.5 M mCPBA solution at 40 °C. Tensile strength of recovered CF (r-CF) measured 4.4 GPa, 93.6% of virgin CF (v-CF), and electrical conductivity reached 590 S/cm, 95% of v-CF. Furthermore, the interfacial shear strength (IFSS) of the recovered carbon fibers (r-CF) using EP resin and polyamide 6 (PA6) was analyzed. For EP resin, the IFSS of r-CF was 88 MPa, a 26 % increase compared to v-CF. In the case of PA6 resin, IFSS values were 80 MPa for r-CF, a 17% improvement over v-CF. The study highlights superior mechanical properties and favorable IFSS of r-CF, positioning them as promising for composite regeneration. Remarkably, this method operated at relatively low temperatures compared to existing technologies, with energy consumption recorded at 35 MJ/kg, establishing it as the most energy-efficient recycling method available.

Synthesis and characterization of mesoporous silica supported metallosalphen-azobenzene complexes: efficient photochromic heterogeneous catalysts for the oxidation of cyclohexane to produce KA oil

The oxidation of cyclohexane to produce KA oil (cyclohexanone and cyclohexanol) is important industrially but faces challenges such as low cyclohexane conversion at high KA oil selectivity, and difficult catalyst recyclability. This work reports the synthesis and evaluation of new heterogeneous catalysts consisting of Co(ii), Mn(ii), Ni(ii) and Cu(ii) salphen-azobenzene complexes [ML1] immobilized on amino-functionalized mesoporous silica (SBA-15, MCM-41, MCM-48) through coordination bonding. In the first step, the salphen-azobenzene ligand was synthesized and complexed with Co, Mn, Ni and Cu metal ions. In the second step, aminopropyltriethoxysilane (APTES) was grafted onto the surface of different types of commercial mesoporous silica. The immobilization of [ML1] onto the mesoporous silica surface and the thermal stability of the obtained materials were confirmed using different characterization techniques such as FT-IR, powder XRD, SEM, TEM, BET, and TGA. The obtained results revealed high dispersion of [ML1] through the silica surface. The catalytic activity of the prepared materials Silica-N-ML1 was evaluated on the cyclohexane oxidation to produce KA oil using various oxidants. The cis-trans isomerization of the azobenzene upon UV irradiation was found to affect the catalytic performance of Silica-N-ML1. The cis isomer of SBA-15-N-CoL1 exhibited the highest cyclohexane conversion (93%) and KA selectivity (92%) under mild conditions (60 °C, 6 h) using m-CPBA as oxidant. Moreover, The SBA-15-N-CoL1 showed high stability during four successive cycles.

Manganese-Mediated Electrochemical Oxidation of Thioethers to Sulfoxides Using Water as the Source of Oxygen Atoms

Oxygen-atom transfer reactions are a prominent class of synthetic redox reactions that often use high-energy oxygen-atom donor reagents. Electrochemical methods can bypass these reagents by using water as the source of oxygen atoms through pathways involving direct or indirect (mediated) electrolysis. Here, manganese porphyrins and related mediators are shown to be effective molecular electrocatalysts for selective oxidation of thioethers to sulfoxides, without overoxidation to the sulfone. The reactions proceed by proton-coupled oxidation of a MnIII-OH2 species to generate a MnIV-OH and MnV═O species. This methodology is compared to direct electrolysis methods initiated by single-electron oxidation of the thioether, and chloride-mediated electrochemical oxidation of thioethers. The Mn-mediated reactions operate at lower applied potential and exhibit improved substrate scope and functional group compatibility relative to direct electrolysis, and the tunability of the Mn-based mediators allows for improved performance relative to chloride-mediated electrolysis. An electrochemical parallel screening platform is developed and applied to a library of pharmaceutically relevant thioethers.

Discovery of a terpene synthase synthesizing a nearly non-flexible eunicellane reveals the basis of flexibility

Eunicellane diterpenoids, containing a typical 6,10-bicycle, are bioactive compounds widely present in marine corals, but rarely found in bacteria and plants. The intrinsic macrocycle exhibits innate structural flexibility resulting in dynamic conformational changes. However, the mechanisms controlling flexibility remain unknown. The discovery of a terpene synthase, MicA, that is responsible for the biosynthesis of a nearly non-flexible eunicellane skeleton, enable us to propose a feasible theory about the flexibility in eunicellane structures. Parallel studies of all eunicellane synthases in nature discovered to date, including 2Z-geranylgeranyl diphosphate incubations and density functional theory-based Boltzmann population computations, reveale that a trans-fused bicycle with a 2Z-configuration alkene restricts conformational flexibility resulting in a nearly non-flexible eunicellane skeleton. The catalytic route and the enzymatic mechanism of MicA are also elucidated by labeling experiments, density functional theory calculations, structural analysis of the artificial intelligence-based MicA model, and mutational studies.

Single-Atom palladium engineered cobalt nanocomposite for selective aerobic oxidation of sulfides to sulfoxides

Developing efficient catalysts for the selective oxidation of sulfides to sulfoxides using molecular oxygen as the oxidant is a challenging task. Here, we report a novel catalyst comprising a single atom palladium engineered cobalt nanocomposite (denoted as PdCo@NC-800-0.01) for this reaction. The incorporation of single atom palladium effectively transforms an originally inactive cobalt nanocomposite into a highly efficient and selective catalyst for the oxidation of sulfides. This catalyst PdCo@NC-800-0.01 exhibited outstanding performance in the selective oxidation of sulfides to sulfoxides using O2 as the oxidant in the presence of isobutyraldehyde (IBA) under mild conditions, demonstrating high activity and excellent selectivity for a broad spectrum of sulfides with good tolerance toward various functional groups, including those susceptible to oxidation. Furthermore, the catalyst could be easily recovered and reused up to 10 times without any significant loss in activity and selectivity. Comprehensive characterizations and theoretical calculations revealed that the engineering of cobalt nanocomposite with single atom Pd greatly enhanced the ability to adsorb and activate IBA, leading to the generation of the key acyl radical. This radical then reacted with singlet oxygen 1O2 derived from molecular oxygen, producing reactive oxygen species peroxy radical, which ultimately promoted the catalytic performance.

Medicinal Chemistry of Drugs with N-Oxide Functionalities

Molecules with N-oxide functionalities are omnipresent in nature and play an important role in Medicinal Chemistry. They are synthetic or biosynthetic intermediates, prodrugs, drugs, or polymers for applications in drug development and surface engineering. Typically, the N-oxide group is critical for biomedical applications of these molecules. It may provide water solubility or decrease membrane permeability or immunogenicity. In other cases, the N-oxide has a special redox reactivity which is important for drug targeting and/or cytotoxicity. Many of the underlying mechanisms have only recently been discovered, and the number of applications of N-oxides in the healthcare field is rapidly growing. This Perspective article gives a short summary of the properties of N-oxides and their synthesis. It also provides a discussion of current applications of N-oxides in the biomedical field and explains the basic molecular mechanisms responsible for their biological activity.

Facile synthesis of dibenzothiophene S-oxides from sulfinate esters

An efficient method to prepare dibenzothiophene S-oxides is disclosed. Suzuki-Miyaura cross-coupling of 2-bromoaryl sulfinate esters with arylboronic acids selectively at the bromo group followed by electrophilic cyclization of the resulting sulfinate ester moiety provides diverse dibenzothiophene S-oxides. Further transformations including Pummerer-type C-H propargylation and aryne reactions realize to synthesize highly functionalized dibenzothiophene derivatives.

Facile and Efficient Production of Biomass-Derived Isosorbide Dioxides via Epoxidation Using In situ-generated DMDO under Ultrasonication

Herein, we present a facile synthetic process for producing biomass-derived isosorbide (ISB) dioxides using dimethyl dioxirane (DMDO) as an efficient oxidizing agent, which was generated in situ from acetone and KHSO5 . To achieve high conversion and product yield, the KHSO5 concentration, KHSO5 flow rate, and reaction temperature were optimized. Under the optimal conditions, rapid and efficient epoxidation using the in situ-generated DMDO was observed under ultrasonication, yielding the desired product within 35 min at 0 °C. This study offers a convenient and efficient method for generating biomass-derived ISB building blocks, which have significant potential for the fabrication of bioplastics.

One-Pot Double Oxidation Synthesis of N-1-Piperidonyl Amides From N-1-Piperidinyl Amides with meta-Chloroperbenzoic Acid: Rimonabant Analogue as Model Study

A simple and efficient one-pot oxidation synthesis of N-1-piperidonyl amides was successfully developed through the double oxidation of hydrazides (involving hydrazonium formation, azodioxy-carbonyl compounds generation, and α-carbon oxidation) by using meta-chloroperbenzoic acid (mCPBA). The convenient oxidation method was also extended to Rimonabant analogue. The lactam oxidized Rimonabant analogue was first successfully synthesized for demonstrating the construction and characterized by NMR spectroscopic methods and the single-crystal X-ray diffraction study (ORTEP).

Stereospecific Single-Pot Route to Chiral Imidazolidines from Aziridines Using a 2D Cu Metal-Organic Framework

The role of coordinatively unsaturated sites (CUS) in metal-organic framework (MOF)-catalyzed organic transformation is vital; however, the design and generation of such sites are challenging. We, therefore, report the synthesis of a novel two-dimensional (2D) MOF, [Cu(BTC)(Mim)]_n (Cu-SKU-3), with pre-existing unsaturated Lewis acid sites. The presence of these active CUS facilitates a ready-to-use attribute in Cu-SKU-3, thereby subsiding the lengthy activation processes associated with MOF-based catalysis. The material has been completely characterized using single crystal X-ray diffraction (SCXRD), powder XRD (PXRD), thermogravimetric analysis (TGA), carbon, hydrogen, and nitrogen (CHN), Fourier-transform infrared (FTIR), and Brunauer-Emmett-Teller (BET) surface area analyses. We directly utilize Cu-SKU-3 for the synthesis of biologically valued chiral imidazolidine motifs in a one-pot fashion starting from aziridines. The chiral imidazolidines are synthesized in good yield (up to 89%) and with high optical purity (ee > 98-99%). Mechanistically, the transformation proceeds in a tandem fashion through stereospecific ring-opening of aziridines followed by the intramolecular cyclization (via sp³ C-H functionalization) reaction forming chiral imidazolidines. The material has an excellent heterogeneous attribute and can be reused several times for one-pot catalytic cycles.

Post-Cyclization Skeletal Rearrangements in Plant Triterpenoid Biosynthesis by a Pair of Branchpoint Isomerases

Triterpenoids possess potent biological activities, but their polycyclic skeletons are challenging to synthesize. The skeletal diversity of triterpenoids in plants is generated by oxidosqualene cyclases based on epoxide-triggered cationic rearrangement cascades. Normally, triterpenoid skeletons then remain unaltered during subsequent tailoring steps. In contrast, the highly modified triterpenoids found in Sapindales plants imply the existence of post-cyclization skeletal rearrangement enzymes that have not yet been found. We report here a biosynthetic pathway in Sapindales plants for the modification of already cyclized tirucallane triterpenoids, controlling the pathway bifurcation between different plant triterpenoid classes. Using a combination of bioinformatics, heterologous expression in plants and chemical analyses, we identified a cytochrome P450 monooxygenase and two isomerases which harness the epoxidation-rearrangement biosynthetic logic of triterpene cyclizations for modifying the tirucallane scaffold. The two isomerases share the same epoxide substrate made by the cytochrome P450 monooxygenase CYP88A154, but generate two different rearrangement products, one containing a cyclopropane ring. Our findings reveal a process for skeletal rearrangements of triterpenoids in nature that expands their scaffold diversity after the initial cyclization. In addition, the enzymes described here are crucial for the biotechnological production of limonoid, quassinoid, apoprotolimonoid, and glabretane triterpenoids.

Asymmetric Rubottom-Type Oxidation Catalyzed by Chiral Calcium Phosphates

A highly efficient catalytic asymmetric Rubottom-type oxidation is described. Using meta-chloroperbenzoic acid (m-CPBA) as the oxidant and chiral calcium phosphate as the catalyst, the facile transformation enables direct hydroxylation of N-Boc oxindoles and β-ketoesters in high yields (up to 99 %) and in a highly enantioenriched fashion (up to >99 % ee). The application of the established method was demonstrated by the synthesis of a pharmaceutically important 3-hydroxyoxindole with excellent enantiocontrol.

Recent progress in the analysis of unsaturated fatty acids in biological samples by chemical derivatization-based chromatography-mass spectrometry methods

Unsaturated fatty acids (UFAs) are essential fatty acids that execute various biological functions in the human body. Therefore, the qualitative and quantitative analysis of UFAs in biological samples can help to clarify their roles in the occurrence and development of diseases, so to reveal the mechanisms of pathogenesis and potential drug intervention strategies. Chromatography-mass spectrometry is one of the most commonly used techniques for the analysis of UFAs in biological samples. However, due to factors such as the complex structural information of UFAs (the number and specific location of CC double bonds) and the low concentration of UFAs in biological samples, it is still difficult to conduct accurate qualitative and/or quantitative studies of UFAs in complex biological samples. In recent years, the integration and application of chemical derivatization and chromatography-mass spectrometry has been widely used in the detection of UFAs. Based on this overview, we reviewed recent developments and application progress for chemical derivatization-based chromatography-mass spectrometry methods for the qualitative and/or quantitative analysis of UFAs in biological samples over the past ten years. Potential trends for the design and improvement of novel derivatization reagents were proposed.

Oxidation-Cyclisation of Biphenyl Thioethers to Dibenzothiophenium Salts for Ultrarapid 18F-Labelling of PET Tracers

¹⁸F-labelled radiotracers are in high demand and play an important role for diagnostic imaging with positron emission tomography (PET). Challenges associated with the synthesis of the labelling precursors and the incorporation of [¹⁸F]fluoride with practical activity yields at batch scale are the main limitations for the development of new ¹⁸F-PET tracers. Herein, we report a high-yielding and robust synthetic method to access naked dibenzothiophenium salt precursors of complex PET tracers and their labelling with [¹⁸F]fluoride. C-S cross-coupling of biphenyl-2-thioacetate with aryl halides followed by sequential oxidation-cyclisation of the corresponding thioethers gives dibenzothiophenium salts in good to excellent yields. Labelling of neutral and electron-deficient substrates with [¹⁸F]fluoride is ultrarapid and occurs under mild conditions (1 min at 90 °C) with high activity yields. The method enables facile synthesis of complex and sensitive radiotracers, as exemplified by radiofluorination of three clinically relevant PET tracers [¹⁸F]UCB-J, [¹⁸F]AldoView and [¹⁸F]FNDP, and can accelerate the development and clinical translation of new ¹⁸F-radiopharmaceuticals.

Mechanistic Study for the Reaction of B12 Complexes with m-Chloroperbenzoic Acid in Catalytic Alkane Oxidations

The oxidation of alkanes with m-chloroperbenzoic acid (mCPBA) catalyzed by the B₁₂ derivative, heptamethyl cobyrinate, was investigated under several conditions. During the oxidation of cyclohexane, heptamethyl cobyrinate works as a catalyst to form cyclohexanol and cyclohexanone at a 0.67 alcohol to ketone ratio under aerobic conditions in 1 h. The reaction rate shows a first-order dependence on the [catalyst] and [mCPBA] while being independent of [cyclohexane]; V_obs = k₂[catalyst][mCPBA]. The kinetic deuterium isotope effect was determined to be 1.86, suggesting that substrate hydrogen atom abstraction is not dominantly involved in the rate-determining step. By the reaction of mCPBA and heptamethyl cobyrinate at low temperature, the corresponding cobalt(III)acylperoxido complex was formed which was identified by UV-vis, IR, ESR, and ESI-MS studies. A theoretical study suggested the homolysis of the O-O bond in the acylperoxido complex to form Co(III)-oxyl (Co-O^•) and the m-chlorobenzoyloxyl radical. Radical trapping experiments using N-tert-butyl-α-phenylnitrone and CCl₃Br, product analysis of various alkane oxidations, and computer analysis of the free energy for radical abstraction from cyclohexane by Co(III)-oxyl suggested that both Co(III)-oxyl and the m-chlorobenzoyloxyl radical could act as hydrogen-atom transfer reactants for the cyclohexane oxidation.

Efficient Oxidation of Cyclohexane over Bulk Nickel Oxide under Mild Conditions

Nickel oxide powder was prepared by simple calcination of nickel nitrate hexahydrate at 500 °C for 5 h and used as a catalyst for the oxidation of cyclohexane to produce the cyclohexanone and cyclohexanol—KA oil. Molecular oxygen (O₂), hydrogen peroxide (H₂O₂), t-butyl hydrogen peroxide (TBHP) and meta-chloroperoxybenzoic acid (m-CPBA) were evaluated as oxidizing agents under different conditions. m-CPBA exhibited higher catalytic activity compared to other oxidants. Using 1.5 equivalent of m-CPBA as an oxygen donor agent for 24 h at 70 °C, in acetonitrile as a solvent, NiO powder showed exceptional catalytic activity for the oxidation of cyclohexane to produce KA oil. Compared to different catalytic systems reported in the literature, for the first time, about 85% of cyclohexane was converted to products, with 99% KA oil selectivity, including around 87% and 13% selectivity toward cyclohexanone and cyclohexanol, respectively. The reusability of NiO catalyst was also investigated. During four successive cycles, the conversion of cyclohexane and the selectivity toward cyclohexanone were decreased progressively to 63% and 60%, respectively, while the selectivity toward cyclohexanol was increased gradually to 40%.

Psilostachyins as trypanocidal compounds: Bioguided fractionation of Ambrosia tenuifolia chemically modified extract

This work focusses on the chemical diversification of an Ambrosia tenuifolia extract and its bioguided fractionation, aiming to unveil the chemical entity responsible for the trypanocidal activity. Besides, a revision of the phytochemical study of this species, based on previous reports of the antiparasitic psilostachyins A and C as main compounds, was conducted. To improve the biological properties of a plant extract through a simple chemical reaction, the oxidative diversification of the dichloromethane extract of this plant species was carried out. A bioguided fractionation of a chemically modified extract was performed by evaluating the inhibitory activity against Trypanosoma cruzi trypomastigotes. This experiment led to the isolation of one of the most active compounds. In general terms, epoxidized metabolites were obtained as a result of the oxidation of the major metabolite of the species. The trypanocidal activity of some tested metabolites overperformed the reference drug, benznidazole, displaying no cytotoxicity at trypanocidal concentrations. Key structure-activity relationships were obtained for designing previously undescribed antiparasitic sesquiterpene lactones.

Homogeneous oxidation of C–H bonds with m-CPBA catalysed by a Co/Fe system: mechanistic insights from the point of view of the oxidant

A Co/Fe system efficiently catalyses the oxidation of C–H bonds with m-CPBA. The nitric acid promoter hampers the m-CPBA homolysis, suppressing the free radical activity. Experimental and computational data evidence a concerted oxidation mechanism.

Rapid Disulfide Mapping in Peptides and Proteins by meta-Chloroperoxybenzoic Acid (mCPBA) Oxidation and Tandem Mass Spectrometry

Disulfide bonds are a class of important post-translational modifications that play important roles in modulating the structures and functions of proteins. Therefore, the mapping of disulfide linkages in peptides and proteins is indispensable for complete structure characterization and functional studies. As disulfide bonds in protonated ions do not dissociate readily under low-energy collision-induced dissociation (CID), they are usually chemically cleaved or activated prior to mass spectrometry (MS) or tandem MS (MS/MS) analysis. In this study, we report a new method that allows the mapping of disulfide linkages in peptides and proteins through meta-chloroperoxybenzoic acid (mCPBA)-based disulfide oxidation and MS/MS. Upon oxidation, the disulfide bond is converted to a thiosulfinate group, i.e., S(═O)-S, in a rapid (>60% yield in 1 min) and highly specific approach in an aqueous phase. The thiosulfinate group is then preferentially cleaved by MS/MS. For interchain disulfide linkages, this leads to a facile peptide chain separation and the identification of disulfide-linked peptides. For intrachain disulfide linkages, collisional activation of the thiosulfinate leads to disulfide cleavage and fragmentation of the peptide backbone constrained by the disulfide loop, enabling a near-complete peptide sequencing. The mCPBA oxidation-based disulfide mapping strategy can be readily integrated with bottom-up or top-down protein analysis for comprehensive protein structure elucidation, e.g., digested lysozyme and intact human insulin.

Catalytic Oxidations with Meta-Chloroperoxybenzoic Acid (m-CPBA) and Mono- and Polynuclear Complexes of Nickel: A Mechanistic Outlook

Selective catalytic functionalization of organic substrates using peroxides as terminal oxidants remains a challenge in modern chemistry. The high complexity of interactions between metal catalysts and organic peroxide compounds complicates the targeted construction of efficient catalytic systems. Among the members of the peroxide family, m-chloroperoxybenzoic acid (m-CPBA) exhibits quite complex behavior, where numerous reactive species could be formed upon reaction with a metal complex catalyst. Although m-CPBA finds plenty of applications in fine organic synthesis and catalysis, the factors that discriminate its decomposition routes under catalytic conditions are still poorly understood. The present review covers the advances in catalytic C–H oxidation and olefine epoxidation with m-CPBA catalyzed by mono- and polynuclear complexes of nickel, a cheap and abundant first-row transition metal. The reaction mechanisms are critically discussed, with special attention to the O–O bond splitting route. Selectivity parameters using recognized model hydrocarbon substrates are summarized and important factors that could improve further catalytic studies are outlined.

Novel (+)-Neoisopulegol-Based O-Benzyl Derivatives as Antimicrobial Agents

Discovery of novel antibacterial agents with new structures, which combat pathogens is an urgent task. In this study, a new library of (+)-neoisopulegol-based O-benzyl derivatives of aminodiols and aminotriols was designed and synthesized, and their antimicrobial activity against different bacterial and fungal strains were evaluated. The results showed that this new series of synthetic O-benzyl compounds exhibit potent antimicrobial activity. Di-O-benzyl derivatives showed high activity against Gram-positive bacteria and fungi, but moderate activity against Gram-negative bacteria. Therefore, these compounds may serve a good basis for antibacterial and antifungal drug discovery. Structure-activity relationships were also studied from the aspects of stereochemistry of the O-benzyl group on cyclohexane ring and the substituent effects on the ring system.

Spirombandakamine A3 and Cyclombandakamines A8 and A9, Polycyclic Naphthylisoquinoline Dimers, with Antiprotozoal Activity, from a Congolese Ancistrocladus Plant

Spirombandakamine A₃ (7) is only the third known naphthylisoquinoline dimer with a spiro-fused novel molecular framework and the first such representative to possess a relative trans-configuration at the two chiral centers in both tetrahydroisoquinoline subunits. It was found in the leaves of a botanically as yet unidentified Congolese Ancistrocladus plant, which is morphologically closely related to the Central African taxon Ancistrocladus ealaensis. Likewise isolated were the new cyclombandakamines A₈ (8) and A₉ (9), which belong to another most recently discovered type of unusual oxygen-bridged naphthylisoquinoline dimers and two previously described "open-chain" analogues, mbandakamines C (10) and D (11). The full absolute stereostructures of these compounds were assigned by combining spectroscopic, chemical, and chiroptical methods. Preliminary biomimetic investigations indicated that both spirombandakamine- and cyclombandakamine-type dimers result from the oxidation of their open-chain mbandakamine-type congeners. The new dimeric alkaloids 7-9 displayed potent growth-inhibitory activity against Plasmodium falciparum, the protozoal pathogen causing malaria, and moderate effects on Trypanosoma brucei rhodesiense, the parasite responsible for African sleeping sickness.

Aminolactonization of Unactivated Alkenes Catalyzed by Aryl Iodine

A one-step protocol of the aryl iodine-catalyzed aminolactonization of unactivated alkenes under oxidation conditions was first reported to efficiently construct diverse amino lactones in a short time using HNTs₂ as the compatible nitrogen source. In addition, we investigated the influence of the reaction rate based on the structure of the iodoarene precatalyst, which revealed the selective adjustment effect on aminolactonization and oxylactonization. Finally, preliminary experiments verified the feasibility of asymmetric aminolactonization catalyzed by a chiral iodoarene precatalyst.

A mild and chemoselective CALB biocatalysed synthesis of sulfoxides exploiting the dual role of AcOEt as solvent and reagent

A mild, chemoselective and sustainable biocatalysed synthesis of sulfoxides has been developed exploiting CALB and using AcOEt with a dual role of more environmentally friendly reaction solvent and enzyme substrate. A series of sulfoxides, including the drug omeprazole, have been synthesised in high yields and with excellent E-factors.

Synthesis of Polycyclic Cyclohexadienone through Alkoxy-Oxylactonization and Dearomatization of 3'-Hydroxy-[1,1'-biphenyl]-2-carboxylic Acids Promoted by Hypervalent Iodine

Alkox-oxylactonization and dearomatization of 3'-hydroxy-[1,1'-biphenyl]-2-carboxylic acid simultaneously promoted by hypervalent iodine have been developed using stoichiometric PhI(OAc)₂ or a catalytic amount of chiral aryl-λ³-iodane generated in situ. This reaction provides a concise method to synthesize diverse polycyclic cyclohexadienones as potential inhibitors of DNA polymerase under mild reaction conditions.

A cascade approach to 3D cyclic carbamates via an ionic decarboxylative functionalization of olefinic oxamic acids

An m-CPBA-mediated intramolecular epoxidation-decarboxylative alkoxylation cascade reaction of olefinic oxamic acids has been developed.

Cobalt Single-Atom-Intercalated Molybdenum Disulfide for Sulfide Oxidation with Exceptional Chemoselectivity

The identification of chemoselective oxidation process en route to fine chemicals and specialty chemicals is a long-standing pursuit in chemical synthesis. A vertically structured, cobalt single atom-intercalated molybdenum disulfide catalyst (Co₁ -in-MoS₂ ) is developed for the chemoselective transformation of sulfides to sulfone derivatives. The single-atom encapsulation alters the electron structure of catalyst owing to confinement effect and strong metal-substrate interaction, thus enhancing adsorption of sulfides and chemoselective oxidation at the edge sites of MoS₂ to achieve excellent yields of up to 99% for 34 examples. The synthetic scopes can be extended to sulfide-bearing alkenes, alkynes, aldehydes, ketones, boronic esters, and amines derivatives as a toolbox for the synthesis of high-value, multifunctional sulfones and late-stage functionalization of pharmaceuticals, e.g., Tamiflu. The synthetic utility of cobalt single atom-intercalated MoS₂ , together with its reusability, scalability, and simplified purification process, renders it promising for industrial productions.

Reinvestigation of the Organocatalyzed Aerobic Oxidation of Aldehydes to Acids

The organocatalyzed aerobic oxidation of aldehydes to acids was reproduced from the original report. In- and ex-situ analysis of the reaction mixture as the function of time reveals that, unlike the claim in the publication, the aerobic oxidation of aromatic and aliphatic aldehydes leads predominantly to the formation of peracids. The latter are transformed into the corresponding carboxylic acids during the workup procedure. The buildup of peracids in solution poses safety problems that should not be overlooked. This finding has also an influence on the way new catalysts are investigated to improve this reaction as well as on aerobic aldehyde-mediated co-oxidation.

Tailoring chemoenzymatic oxidation via in situ peracids

Epoxidation chemistry often suffers from the challenging handling of peracids and thus requires in situ preparation. Here, we describe a two-phase enzymatic system that allows the effective generation of peracids and directly translate their activity to the epoxidation of olefins. We demonstrate the approach by application to lipid and olefin epoxidation as well as sulfide oxidation. These methods offer useful applications to synthetic modifications and scalable green processes.