Divergent synthesis of complex withanolides enabled by a scalable route and late-stage functionalization.

Withanolides are a group of naturally occurring C steroids based on an ergostane skeleton. They have a high degree of polyoxygenation, and the abundance of -functional groups has enabled various natural alterations to both the carbocyclic skeleton and the side chain. Consequently, these molecules have intricate structural features that lead to their highly varied display of biological activities including anticancer, anti-inflammatory, and immunomodulating properties.

Asymmetric synthesis of sulfoximines, sulfonimidoyl fluorides and sulfonimidamides enabled by an enantiopure bifunctional S(VI) reagent.

An increased interest to expand three-dimensional chemical space for the design of new materials and medicines has created a demand for isosteric replacement groups of commonly used molecular functionality. The structural and chemical properties of chiral S(VI) functional groups provide unique spatial and electronic features compared with their achiral sulfur- and carbon-based counterparts. Manipulation of the S(VI) centre to introduce structural variation with stereochemical control has remained a synthetic challenge.

Triazole-modified Ru-carbene complexes: A valid olefin metathesis pre-catalyst for dynamic covalent chemistry via C=C bond formation.

The 1,2,3-triazole coordinated ruthenium carbene complexes (TA-Ru) were reported for the first time as a new class of modified Grubbs catalyst to achieve challenging olefin metathesis at higher temperatures without catalyst decomposition. Previously reported N-tethered Ru-carbene complexes all suffered from rapid isomerization, causing significantly reduced catalyst reactivity. These new TA-Ru complexes hold the active -dichloro conformation even at 80 °C, allowing effective olefin metathesis for challenging substrates.

Asymmetric Hydrative Aldol Reaction (HAR) via Vinyl-Gold Promoted Intermolecular Ynamide Addition to Aldehydes.

Herein, we reported an intermolecular asymmetric hydrative aldol reaction through vinyl-gold intermediate under ambient conditions. This tandem alkyne hydration and sequential nucleophilic addition afforded a "base-free" approach to β-hydroxy amides with high efficiency (up to 95 % yields, >50 examples). Vinyl gold intermediate was applied as reactive nucleophile and Fe(acac) was used as the critical co-catalyst to prevent undesired protodeauration, allowing this transformation to proceed under mild conditions with good functional group tolerance and excellent stereoselectivity (>20 : 1 d.

Study on the inhibitory mechanism of dehydrogenated antioxidants on coal spontaneous combustion.

In order to comprehensively and systematically analyze the reasons why antioxidant inhibitors can scavenge free radicals in coal and inhibit coal spontaneous combustion, this paper studies the effects of VC, TBHQ, EGCG and BHT on coal spontaneous combustion by means of coal spontaneous combustion characteristics experiments and quantum chemical simulation methods. The low-temperature oxidation characteristics of coal were studied through temperature-programmed experiments. The results showed that the CO emission of coal samples with antioxidants was significantly lower than that of raw coal.

Tongalides, Halogenated Butenolides from an Antarctic sp. Rhodophyte.

Six new halogenated butenolides, tongalides A-C (-) and their acetylated congeners (-), were isolated from an extract of the Antarctic rhodophyte sp. that displayed significant antibiotic activity. The structures of the compounds were determined by analysis of data acquired by spectroscopic and spectrometric techniques including NMR, HRESIMS, optical rotation, and X-ray diffraction studies.

Design and synthesis of stable four-coordinated benzotriazole-borane with tunable fluorescence emission.

A new class of stable four-coordinated benzotriazole-borane compounds was developed gold-catalyzed alkyne hydroboration. The application of polymeric (BHCN) reagent gave the formation of cyano-amine-boranes (CAB) complexes with less basic N-heterocyclic amines and anilines. Various new CABs were investigated in catalytic hydroboration to synthesize N-B cycles.

Synthesis of microporous hydrogen-bonded supramolecular organic frameworks through guanosine self-assembly.

Extending the structural hierarchy and complexity through small-molecular self-assembly is a powerful way to obtain large discrete, functional molecular architecture. A hydrogen-bonded supramolecular organic framework (HOF) with nanometer-size pores is constructed in a solid state with simple guanosine-monomer self-assembly. To extend the hierarchy of the G-quartet self-assembly to a higher order thanthatofthetraditionalG-quadruplex,H-bondacceptorsontheC-8 position of guanosine are introduced to establish inter-quadruplex linkage via H bonding to N(2)-H from the neighboring G-quartet.

Metallo-Supramolecular Octahedral Cages with Three Types of Chirality towards Spontaneous Resolution.

Chirality is one of the most important intrinsic properties of (supra)molecules. In this study, we obtained enantiomeric metallo-supramolecular octahedra without using any chiral sources. Such cages were self-assembled by prochiral trispyridine ligand L based on a C truxene core and Cu salts.

Conformational Control of a Metallo-Supramolecular Cage via the Dissymmetrical Modulation of Ligands.

In nature as well as life systems, the presence of asymmetrical and dissymmetrical structures with specific functions is extremely common. However, the construction of metallo-supramolecular assemblies based on dissymmetrical ligands still remains a considerable challenge for avoiding the generation of unexpected isomers with similar thermodynamic stabilities, especially for three-dimensional supramolecular structures. In this study, a strategy for the conformational control of metallo-supramolecular cages via the enhancement of ligand dissymmetry was proposed.

Functional Porphyrinic Metal-Organic Framework as a New Class of Heterogeneous Halogen-Bond-Donor Catalyst.

Biomimetic metal-organic frameworks have attracted great attention as they can be used as bio-inspired models, allowing us to gain important insights into how large biological molecules function as catalysts. In this work, we report the synthesis and utilization of such a metal-metalloporphyrin framework (MMPF) that is constructed from a custom-designed ligand as an efficient halogen bond donor catalyst for Diels-Alder reactions under ambient conditions. The implementation of fabricated halogen bonding capsule as binding pocket with high-density C-Br bonds enabled the use of halogen bonding to facilitate organic transformations in their three-dimensional cavities.

Anion mediated, tunable isoguanosine self-assemblies: decoding the conformation influence and solvent effects.

Systematic investigations were performed with various substituted groups at C8 purine and ribose. A series of isoG analogs, C8-phenyl substituted isoG were synthesized and applied for Cs coordination. The structural proximity between purine and ribose limited pentaplex formation for C8-phenyl substituted isoG derivatives.

Construction of Stable Helical Metal-Organic Frameworks with a Conformationally Rigid "Concave Ligand".

A helical metal-organic framework was prepared by using a conformationally rigid tetratopic benzoic acid ligand with binding units pointing toward each other (concave ligand). To avoid the obvious intramolecular interactions between binding units, matching spacing groups were applied to introduce atropic repulsion, thereby allowing the formation of extended frameworks for the first time. With this new ligand design, a helical-shaped MOF with significantly improved air and moisture stability was successfully prepared, thus providing a new strategy for ligand design toward porous material constructions.

Highly Stable Single Crystals of Three-Dimensional Porous Oligomer Frameworks Synthesized under Kinetic Conditions.

Various robust, crystalline, and porous organic frameworks based on in situ-formed imine-linked oligomers were investigated. These oligomers self-assembled through collaborative intermolecular hydrogen bonding interactions via liquid-liquid interfacial reactions. The soluble oligomers were kinetic products with multiple unreacted aldehyde groups that acted as hydrogen bond donors and acceptors and directed the assembly of the resulting oligomers into 3D frameworks.

Alkyne Trifunctionalization via Divergent Gold Catalysis: Combining π-Acid Activation, Vinyl-Gold Addition, and Redox Catalysis.

Here we report the first example of alkyne trifunctionalization through simultaneous construction of C-C, C-O, and C-N bonds via gold catalysis. With the assistance of a γ-keto directing group, sequential gold-catalyzed alkyne hydration, vinyl-gold nucleophilic addition, and gold(III) reductive elimination were achieved in one pot. Diazonium salts were identified as both electrophiles (N source) and oxidants (C source).

A MOF-based Ultra-Strong Acetylene Nano-trap for Highly Efficient C H /CO Separation.

Porous materials with open metal sites have been investigated to separate various gas mixtures. However, open metal sites show the limitation in the separation of some challenging gas mixtures, such as C H /CO . Herein, we propose a new type of ultra-strong C H nano-trap based on multiple binding interactions to efficiently capture C H molecules and separate C H /CO mixture.

Efficient separation of xylene isomers by a guest-responsive metal-organic framework with rotational anionic sites.

The separation of xylene isomers (para-, meta-, orth-) remains a great challenge in the petrochemical industry due to their similar molecular structure and physical properties. Porous materials with sensitive nanospace and selective binding sites for discriminating the subtle structural difference of isomers are urgently needed. Here, we demonstrate the adaptively molecular discrimination of xylene isomers by employing a NbOF-pillared metal-organic framework (NbOFFIVE-bpy-Ni, also referred to as ZU-61) with rotational anionic sites.

Facilitating Ir-Catalyzed C-H Alkynylation with Electrochemistry: Anodic Oxidation-Induced Reductive Elimination.

An electrochemical approach in promoting directed C-H alkynylation with terminal alkyne via iridium catalysis is reported. This work employed anodic oxidation of Ir(III) intermediate (characterized by X-ray crystallography) to promote reductive elimination, giving the desired coupling products in good yields (up to 95%) without the addition of any other external oxidants. This transformation is suitable for various directing groups with H as the only by-product, which warrants a high atom economy and practical oxidative C-C bond formation under mild conditions.

"Orthogonal-Twisted-Arm" Ligands for The Construction of Metal-Organic Frameworks (MOFs): New Topology and Catalytic Reactivity.

Extended tetratopic benzoic acid ligands with "orthogonal-twisted-arms" conformations were designed and synthesized for the construction of new MOF structures (OTA-MOF). Upon coordination with Cd and Cu cations, two well-defined new MOFs were prepared. X-ray single crystal structures were successfully obtained, demonstrating the formation of a new topology (4,4,4-c).

Regioselective Crossed Aldol Reactions under Mild Conditions via Synergistic Gold-Iron Catalysis.

A synergistic gold/iron catalytic system was developed for sequential alkyne hydration and vinyl gold addition to aldehydes or ketones. Fe(acac) was identified as an essential co-catalyst in preventing vinyl gold protodeauration and facilitating nucleophilic additions. Effective C-C bond formation was achieved under mild conditions (r.

Diazo Activation with Diazonium Salts: Synthesis of Indazole and 1,2,4-Triazole.

A donor/acceptor diazo activation strategy, processing via condensation using diazonium salts without the addition of any other catalysts or reagents, is reported. The diazenium intermediate was found to undergo cyclization to give indazoles in excellent yields. Alternatively, in the presence of nitriles, substituted 1,2,4-triazoles were obtained in good to excellent yields.

A Porous Organic Polymer Nanotrap for Efficient Extraction of Palladium.

To offset the environmental impact of platinum-group element (PGE) mining, recycling techniques are being explored. Porous organic polymers (POPs) have shown significant promise owing to their selectivity and ability to withstand harsh conditions. A series of pyridine-based POP nanotraps, POP-Py, POP-pNH -Py, and POP-oNH -Py, have been designed and systematically explored for the capture of palladium, one of the most utilized PGEs.