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We describe the development of a Pd‐catalyzed decarboxylative asymmetric allylic alkylation of α‐nitro allyl esters to afford acyclic tetrasubstituted nitroalkanes. Optimization of the reaction parameters revealed unique ligand and solvent combinations crucial for achieving chemo‐ and enantioselective C‐alkylation of electronically challenging benzylic nitronates and sterically encumbered 2‐allyl esters. Substrates were efficiently accessed in a combinatorial fashion by a cross‐Claisen / α‐arylation sequence. The method provides functional group orthogonality that complements nucleophilic imine allylation strategies for α‐tertiary amine synthesis.
Photocatalytic reduction of CO2 to value‐added fuel has been considered to be a promising strategy to reduce global warming and shortage of energy. Rational design and synthesis of catalysts to maximumly expose the active sites is the key to activate CO2 molecule and determine the reaction selectivity. Here, we synthesize a well‐defined copper‐based boron imidazolate cage (BIF‐29) with exposed six mononuclear copper for photocatalytic reduction of CO2. Theoretical calculations uncover single Cu site including weak coordinated water delivers a new state on conduction band near the Fermi level and stabilizes *COOH intermediate. Steady‐state and time‐resolved fluorescence spectra elucidate these Cu sites efficiently promote the separation of e.
Strategies to achieve spatiotemporal regulation of pre‐existing alkenes via external stimuli are essential given the ubiquity of feedstock olefins in chemistry and their downstream applications. Mirroring the 1‐0 switch that underpins mammalian vision through selective geometric isomerisation in retinal, strategies to manipulate 2D space by both geometric and positional isomerisation of alkenes via chemical, thermal and light driven processes are being intensively pursued. This mini‐review highlights the current state of the art in activating and achieving directionality in these fundamental chemical transformations.
Methoxyphosphinidene oxide (CH3OPO) and isomeric methyldioxophosphorane (CH3PO2) are key intermediates in the degradation of organophosphorus compounds (OPCs). Unlike the nitrogen analogues CH3ONO and CH3NO2, the experimental data about these two prototypical OPCs are scarce. By high vacuum flash pyrolysis (HVFP) of diazide CH3OP(O)(N3)2 at 1000 K, the cis and trans conformers of CH3OPO have been generated in the gas phase and subsequently isolated in cryogenic Ar and N2 matrices for IR spectroscopy characterization. Upon 266 nm laser irradiation, cis → trans conformational conversion occurs in CH3OPO with concurrent isomerisation to CH3PO2. The spectroscopic identification of CH3OPO and CH3PO2 is supported by D‐, 13C‐, and 18O‐isotope labe.
Salmon and Lister would be proud: The development of new chemiluminescence probes for the direct detection of two of the most widely distributed and deadliest food‐borne pathogenic bacteria, Salmonella and Listeria monocytogenes, is described. The two probes could detect their corresponding bacteria with a limit of detection about 600‐fold lower than that of fluorescent probes. Abstract. Detection of Salmonella and L. monocytogenes in food samples by current diagnostic methods requires relatively long time to results (2–6 days). Furthermore, the ability to perform environmental monitoring at the factory site for these pathogens is limited due to the need for laboratory facilities. Herein, we report new chemiluminescence probes for the ultras.
We herein report a stereospecific 1,4‐metallate rearrangement for single geometric ketoxime synthesis from oxime chlorides and arylboronic acids, this strategy exhibits broad substrate scope with excellent stereoselectivity under mild conditions. In comparison with the conventional approaches, two single configurations of unsymmetric diaryl oximes and thermodynamically less stable Z‐isomer of aryl alkyl ketoxime can be selectively and exclusively obtained. The reactivity of unsymmetric diaryl oximes or Z‐isomer of aryl alkyl oximes, a class of molecules underexplored, enables efficient access to corresponding isoquinolines, isoquinoline N‐oxides and amides with one single configuration.
Elucidating at atomic level how proteins interact and are chemically modified in cells represents a leading frontier in structural biology. We have developed a tailored solid‐state NMR approach that allows studying protein structure inside humans cells at atomic level under high‐sensitivity DNP conditions. We demonstrate the method on Ubiquitin (Ub) which is criticially involved in cellular functioning. Our results pave the way for structural studies of larger proteins or protein complexes inside human cells which have remained elusive for in‐cell solution‐state NMR due to molecular size limitations.
Emerging anionic redox chemistry has demonstrated that surface lattice oxygen in transition metal oxides plays a vital role in catalytic process. Mastering activation method of surface lattice oxygen and identifying activation mechanism at the atomic level are crucial for development and design of advanced catalysts. Herein, we develop a novel strategy that creating a spinel Co3O4/perovskite La0.3Sr0.7CoO3 interface by in‐situ reconstruction of surface Sr enrichment region in LSC to activate surface lattice oxygen. Experimentally, advanced XAS and XPS prove that the regulated chemical interface optimizes the hybridized orbital between Co 3d and O 2p and triggers more electrons in oxygen site of LSC transferred into lattice of Co3O4, leading.
Photonic materials use photons as information carriers and offer the potential for unprecedented applications in optical and optoelectronic devices. Controllable photon manipulation can be achieved by construction of macroscopic crystalline heterostructures with tunable composition that can offer control over nanoscale structure and properties. In this study, we introduce a new strategy for photonic materials using metal‐organic frameworks (MOFs) as the host for the rational construction of donor‐acceptor (D‐A) heterostructure crystals. We have engineered a rich library of heterostructure crystals using the MOF NKU‐111 as a host. NKU‐111 is based upon an electron‐deficient tridentate ligand (acceptor, A) that can bind to various electron‐ri.
Nitroimidazoles are one of the most effective ways to treat anaerobic bacterial infections. Synthetic nitroimidazoles are inspired by the structure of azomycin, isolated from Streptomyces eurocidicus in 1953. Despite its foundational role, no biosynthetic gene cluster for azomycin has been found. Guided by bioinformatics, we identified a cryptic biosynthetic gene cluster in Streptomyces cattleya and then carried out in vitro reconstitution to deduce the enzymatic steps in the pathway linking L‐arginine to azomycin. The gene cluster we discover is widely distributed among soil‐dwelling actinobacteria and proteobacteria, suggesting that azomycin and related nitroimidazoles may play important ecological roles. Our work sets the stage for devel.
Oil paints comprise pigments, drying oils and additives that together confer desirable properties, but can react to form metal carboxylates (soaps) that may damage artworks over time. To obtain information on soap formation and aggregation, we introduce a new tapping‐mode measurement paradigm for the photothermal induced resonance (PTIR) technique that enables nanoscale IR spectroscopy and imaging on highly heterogenous and rough paint thin sections. PTIR is used in combination with µ‐computed tomography and IR microscopy to determine the distribution of metal carboxylates in a 23‐year old oil paint of known formulation. Results show that heterogeneous agglomerates of Al‐stearate and a Zn‐carboxylate complex with Zn‐stearate nano‐aggregates.
Understanding how chemical bonds are formed and broken is the foundation of molecular design. Observing these processes in individual molecules promises levels of detail and precision beyond those achieved through traditional ensemble techniques. Here we develop a single‐molecule method based on the scanning tunneling microscope (STM) to selectively couple a series of aniline derivatives and create azobenzenes. The Au‐catalyzed oxidative coupling is driven by the local electrochemical potential at the nanostructured Au STM tip. The products are detected in situ by measuring the conductance and molecular junction elongation and compared with analogous measurements of the expected azobenzene derivatives prepared ex situ. This approach is robu.
Silicon analogues of ketones have remained elusive for more than 150 years. In their Communication (DOI: 10.1002/anie.201905198), T. Iwamoto and co‐workers report the first synthesis of an isolable silicon analogue of a ketone that exhibits a three‐coordinate silicon center and an unperturbed Si=O bond. This genuine silanone does not require coordination of Lewis bases and acids or the introduction of electron‐donating groups to stabilize the Si=O bond.
We have developed a caged neurotransmitter using an extended π‐electron chromophore for efficient multiphoton uncaging on living neurons. Widely studied in a chemical context, such chromophores are inherently bioincompatible due to their highly lipophilic character. Attachment of two polycarboxylate dendrimers, a method we call "cloaking", to a bisstyrylthiophene (or BIST) core effectively transformed the chromophore into a water‐soluble optical bioprobe, whilst maintaining the high two‐photon absorption of >500 GM. Importantly, the cloaked caged compound was biologically inert at high concentrations required for multiphoton chemical physiology. Thus, in contrast to non‐cloaked BIST compounds, this allowed safe delivery of a BIST‐caged neur.
Abstract: A new class of intermolecular olefin aminooxygenation reaction is described. This reaction utilizes the classic halonium intermediate, as a regio‐ and stereochemical template, to accomplish the selective oxyamination of both activated and unactivated alkenes. Notably, urea chemical feedstock can be directly introduced as the N‐ and O‐source and simple iodide salt can be utilized as the catalyst. This formal [3+2] cycloaddition process provides a highly modular entry to a range of useful heterocyclic products with excellent selectivities and functional group tolerance.
Syn dihydroxyketone motifs are embedded in a wide range of biologically active natural products, however development of stereoselective synthetic methods to assemble these structures has proven a challenging task to date. We report here a highly diastereoselective method for synthesis of complex syn dihydroxyketones from propargylic alcohols, with wide scope for application in natural product synthesis. The reaction sequence involves regioselective cyclisation of propargylic alcohols with incorporation of a triketone to give enol dioxolanes that are then diastereoselectively epoxidised to form unusual spiroepoxide intermediates. Hydrolysis affords syn dihydroxyketones as essentially single diastereomers. The reaction sequence is operational.
Metal‐organic frameworks (MOFs) are a class of porous materials that show promise in the removal of Toxic Industrial Chemicals (TICs) from contaminated airstreams, though their development for this application has so far been hindered by issues of water stability and the wide availability and low cost of traditionally used activated carbons.
Covalent bond–forming protein domains can be versatile tools for creating unconventional protein topologies. In this study, through rewiring SpyTag‐SpyCatcher complex to induce rationally designed chain entanglement, we developed a biologically enabled active template for concise, modular and programmable synthesis of protein heterocatenanes both in vitro and in vivo. It is a general and good‐yielding reaction for forming heterocatenanes with precisely controlled ring sizes and broad structural diversity. More importantly, such hetero‐catenation not only provides an efficient means of bioconjugation for integrating multiple native bio‐functions, but also enhances the component proteins’ stability against proteolytic digestion, thermal unfol.
Schrock–Osborn type cationic rhodium phosphine complexes, discovered and extensively studied since the 1970s, have formed the foundation of modern homogeneous and asymmetric catalysis. Cobalt, the first‐row congener of rhodium, is an attractive surrogate for this privileged class of catalysts, yet their cobalt analogues have remained elusive for over 40 years. In their Communication (DOI: 10.1002/anie.201903766), P. J. Chirik and co‐workers report the first syntheses and characterization of these sought‐after cobalt complexes and their performance in asymmetric hydrogenation reactions.

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