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Twelve compounds, including four undescribed cytochalasins, xylariachalasins A–D (1–4), four undescribed polyketides (5–8), and four known cytochalasins (9–12), were isolated from the mangrove endophytic fungus Xylaria arbuscula QYF. Their structures and absolute configurations were established by extensive spectroscopic analyses (1D and 2D NMR, HRESIMS), electronic circular dichroism (ECD) calculations, 13C NMR calculation and DP4+ analysis, single-crystal X-ray diffraction, and the modified Mosher ester method. Compounds 1 and 2 are rare cytochalasin hydroperoxides. In bioactivity assays, Compound 2 exhibited moderate antimicrobial activities against Staphylococcus aureus and Candida albicans with MIC values of 12.5 μM for both Compound 10 exhibited significant cytotoxic activity against MDA-MB-435 with an IC50 value of 3.61 ± 1.60 μM. [ABSTRACT FROM AUTHOR]

Benzyne derived from hexadehydrogenated Diels Alder (HDDA) reactions was found to be an efficient hydrosilylation acceptors. Various silanes can react smoothly with HDDA‐derived benzyne to give the arylation products. Lewis acid such as boron trifluoride etherate can accelerate these hydrosilylation reactions. Polyhydromethylsiloxane (PHMS), a widely used organosilicon polymer, was also successfully modified using our method. About 5 % of Si−H bonds in the polymer were inserted by benzynes, giving a functional PHMS with much more solubility in methanol and with a blue‐emitting fluorescence behavior. Mechanism research shows that the insertion of benzyne into the Si−H bond probably undergoes a synergistic pathway, which is quite different from the traditional radical‐initiated hydrosilylation or transition‐metal‐catalyzed hydrosilylation. [ABSTRACT FROM AUTHOR]

Colloidal silicon nanocrystals (SiNCs) have garnered significant interest in optoelectronics and biomedical applications. Direct arylation provides pathways to enhance the solution processability of particles and manipulate the photophysical and electronic properties of SiNCs. Unfortunately, existing methods employed to prepare aryl‐functionalized SiNCs are based on organometallic coupling or transition‐metal‐catalyzed strategies, which require metal‐based reagents for preactivation or the precursors and complicated post‐treatment processes for product purification. Herein, we demonstrate a metal‐free method that directly functionalizes SiNCs with aryl‐based ligands. We design a series of benzyne derivatives formed from the thermal cyclization of predesigned alkynes, allowing efficient arylation on hydride‐terminated silicon surfaces under mild conditions. These aryl‐functionalized SiNCs exhibit strong blue emissions with nanosecond‐scaled decay, suggesting the formation of a new radiative recombination channel on SiNC surfaces. [ABSTRACT FROM AUTHOR]

A metal‐free and external‐oxidant‐free electrosynthesis of β‐acyloxy‐γ‐selenyl amines was developed. The cascade reaction is triggered by anodic oxidative generation of electrophilic selenium cation, followed by electrophilic addition to the unactivated alkene, and successive water promoted intramolecular acyl migration. The reactions gave the products in up to 98% yield with controllable regio‐ and diastereoselectivities. Different chemoselectivity towards cyclization products was also viable with N‐Boc and N‐Cbz substrates. Both batch chemistry and flow chemistry were available for scale‐up synthesis with up to 91% yield. [ABSTRACT FROM AUTHOR]

An electrochemically initiated heteroaryltrifluoromethylation of allylic amines was developed. The cascade reaction involved the anodic oxidation of Langlois reagent (CF3SO2Na) to generate CF3 radicals, followed by radical addition to the inactivated alkene, Smiles-type heteroaryl migration, and the reduction of nitrogen radicals. Unlike the conventional oxidative reaction mode, the SO2 molecules from the Langlois reagent and Smiles rearrangement probably served as chemical reductants in the reaction cascade, giving a redox-neutral electrosynthesis. The reaction exhibited excellent regioselectivity and stereoselectivity. It provides an efficient method for the synthesis of enantiomerically pure β-heteroaryl-γ-trifluoromethyl amines and the stereoselective late-stage modification of biologically active compounds. [ABSTRACT FROM AUTHOR]

Electrosynthesis has recently attracted more and more attention due to its great potential to replace chemical oxidants or reductants in molecule‐electrode electron transfer. Sulfonyl compounds such as sulfonyl hydrazides, sulfinic acids (and their salts), sulfonyl halides have been discovered as practical precursors of several radicals. As electrochemical redox reactions can provide green and efficient pathways for the activation of sulfonyl compounds, studies for electrosynthesis have rapidly increased. Several types of radicals can be generated from anodic oxidation or cathodic reduction of sulfonyl compounds and can initiate fluoroalkylation, benzenesulfonylation, cyclization or rearrangement. In this Review, we summarize the electrosynthesis developments involving sulfonyl compounds mainly in the last decade. [ABSTRACT FROM AUTHOR]

Metal halide perovskite nanocrystals (PNCs) have aroused worldwide research interest for optoelectronics. Herein, we report the first electrochemical approach to prepare colloidal PNCs with drastically reduced consumption of salts, solvents, and ligands. This method can be extended to prepare mixed-halide and bismuth-based PNCs by changing precursor compositions and metal components. [ABSTRACT FROM AUTHOR]

Owing to the importance of arene moieties in organic chemistry, methods for arene construction attract great attention. Besides the traditional substitution strategy from pre-existing arenes, the straightforward formation of arene cores can also provide significant shortcuts towards a wide array of target molecules with different substitution patterns. Among direct arene formation reactions, applying environmentally benign organocatalysis to access arene moieties continues to attract increasing attention. This short review provides a brief summary of recent progress on organocatalyzed de novo (hetero)arene formation and applications in enantioselective synthesis. 1 Introduction 2 Arene Formation with Non-Covalent Organocatalysts 2.1 Arene Formation with Acid Organocatalysts 2.2 Arene Formation with Base Organocatalysts 2.3 Arene Formation with Hydrogen-Bonding Organocatalysts 3 Arene Formation with Covalent Organocatalysts 3.1 Arene Formation with Lewis Base Organocatalysts 3.1.1 Arene Formation with Secondary Amine Organocatalysts 3.1.2 Arene Formation with Tertiary Amine, Tertiary Phosphine and Sulfide Organocatalysts 3.1.3 Arene Formation with N-Heterocyclic Carbene Organocatalysts 3.2 Arene Formation with Lewis Acid Organocatalysts 4 Conclusion [ABSTRACT FROM AUTHOR]

In recent decades, organocatalysis by N-heterocyclic carbenes (NHCs) has emerged as a versatile and powerful method in organic synthesis. As a result of the power of NHC organocatalysis to produce cyclic compounds, polysubstituted benzenes, which are among the most important cyclic compounds in organic chemistry, can be synthesized efficiently and selectively. This article briefly summarizes the history of NHC organocatalysis, including recent developments in benzene-formation methods, and highlights our recent work in atroposelective arene formation by carbene-catalyzed formal [4+2] cyclo-additions. We expect that more NHC-catalyzed methods for the synthesis of asymmetric arenes will be developed in the near future, providing shortcuts to syntheses of sophisticated chiral functional molecules with polysubstituted benzene nuclei. [ABSTRACT FROM AUTHOR]

Atroposelective arene formation is an efficient method to build axially chiral molecules with multi‐substituted arenes. Reported here is an organocatalyzed atroposelective arene formation reaction by an N‐heterocyclic carbene (NHC) catalyzed formal [4+2] cycloaddition of conjugated dienals and α‐aryl ketones. This study expands the synthetic potential of NHC organocatalysis and provides a competitive pathway for the synthesis of axially chiral ligands, catalysts, and other functional molecules. [ABSTRACT FROM AUTHOR]

Multisubstituted arenes such as indanes with attached all‐carbon quaternary centers are unique scaffolds in synthetic functional molecules and sophisticated natural products. A key challenge in preparing such molecules lies in the enantioselective installation of the quaternary carbon centers. Conventional methods in this direction include asymmetric substitution reactions and substrate‐controlled cyclization reactions. These reactions lead to poor stereoselectivities and/or require long and tedious synthetic steps. Disclosed here is a one‐step organic catalytic strategy for enantioselective access to this class of molecules. The reaction involves an N‐heterocyclic carbene catalyzed process for direct benzene construction, indane formation, remote‐carbon desymmetrization, and excellent chirality control. This approach will enable the concise synthesis of arene‐containing molecules, including those with complex structures and challenging chiral centers. [ABSTRACT FROM AUTHOR]

This report describes a facile strategy to enhance the catalytic selectivity by tuning the pore sizes of metal–organic frameworks (MOFs) in nanoparticles (NPs)/MOF composite catalysts. A general post-synthetic modification method was used to adjust the pore sizes of MOFs by using anhydrides with different chain lengths to react with amino groups in the ligands. The modified NPs/MOF catalysts exhibited enhanced size selectivity performance in the hydrogenation of olefins, which revealed the flexibility of MOFs as supporting materials for heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

A new catalytic approach for rapid asymmetric access to spirocycles is disclosed. The reaction involves a carbene‐ and thiourea‐cocatalyzed desymmetrization process with the simultaneous installation of a spirocyclic core. The use of a thiourea cocatalyst is critical to turn on this reaction, as no product was formed in the absence of a thiourea. Our study constitutes the first success in the carbene‐catalyzed enantioselective synthesis of all‐carbon spirocycles. The reaction products can be readily transformed into sophisticated multicyclic molecules and chiral ligands. Harmony between cats: Dual carbene and thiourea catalysis enabled rapid asymmetric access to spirocyclic compounds by a desymmetrization process (see scheme). The presence of the thiourea cocatalyst was essential for this carbene‐catalyzed enantioselective synthesis of all‐carbon spirocycles to proceed. The reaction products can be readily transformed into sophisticated multicyclic molecules and chiral ligands. [ABSTRACT FROM AUTHOR]

Benzocoumarin is an important structural motif widely found in natural products and synthetic molecules. Traditional methods for the synthesis of benzocoumarins and their derivatives require multiple steps, typically with an intramolecular ester forming reaction to make the lactone ring as the last step. Another major method involves transition metal-catalyzed coupling or carbon-hydrogen bond activation reactions starting with pre-existing aryl frameworks in the substrates. Here we report a new strategy for the green and rapid access to benzocoumarins and their derivatives. Our method uses readily available unsaturated aldehydes and coumarins as the substrates and air as the green oxidant. The overall reaction proceeds through a formal [4+2] process to construct a new benzene ring and thus to afford benzocoumarins in essentially a single step. No metal catalysts were used; no toxic or expensive reagents were involved. The power of our new approach is further demonstrated in a concise formal total synthesis of cannabinol, a bioactive natural product. [ABSTRACT FROM AUTHOR]

Organocatalytic ester activation is developed for a highly selective cascade reaction between saturated esters and amino enones. The reaction involves activation of the β-carbon atom of the ester as a key step. This method allows a single-step access to multicyclic oxoquinoline-type heterocycles with high enantiomeric ratios. [ABSTRACT FROM AUTHOR]

Exploration of high‐performance cathode materials for rechargeable aqueous Zn ion batteries (ZIBs) is highly desirable. The potential of molybdenum trioxide (MoO3) in other electrochemical energy storage devices has been revealed but held understudied in ZIBs. Herein, a demonstration of orthorhombic MoO3 as an ultrahigh‐capacity cathode material in ZIBs is presented. The energy storage mechanism of the MoO3 nanowires based on Zn2+ intercalation/deintercalation and its electrochemical instability mechanism are particularly investigated and elucidated. The severe capacity decay of the MoO3 nanowires during charging/discharging cycles arises from the dissolution and the structural collapse of MoO3 in aqueous electrolyte. To this end, an effective strategy to stabilize MoO3 nanowires by using a quasi‐solid‐state poly(vinyl alcohol)(PVA)/ZnCl2 gel electrolyte to replace the aqueous electrolyte is developed. The capacity retention of the assembled ZIBs after 400 charge/discharge cycles at 6.0 A g−1 is significantly boosted, from 27.1% (in aqueous electrolyte) to 70.4% (in gel electrolyte). More remarkably, the stabilized quasi‐solid‐state ZIBs achieve an attracting areal capacity of 2.65 mAh cm−2 and a gravimetric capacity of 241.3 mAh g−1 at 0.4 A g−1, outperforming most of recently reported ZIBs. [ABSTRACT FROM AUTHOR]

The title procedure can be successfully applied to the construction of a broad spectrum of benzocoumarin derivatives starting from 3-acetylcoumarins and unsaturated aldehydes (loss of acetic acid). [ABSTRACT FROM AUTHOR]

An abstract of the article "N-Heterocyclic Carbene-Catalyzed δ-Carbon LUMO Activation of Unsaturated Aldehydes" by T. Zhou and colleagues is presented.

Background: Nonobvious early symptoms are a prominent characteristic of pancreatic cancer, resulting in only 20% of patients having resectable tumors at the time of diagnosis. The optimal management of unresectable advanced pancreatic cancer (UAPC) remains an open research question. In this study, the tumors shrank significantly after PD-1 antibody combined with chemotherapy in two UAPC patients, and both have achieved R0 (pathologically negative margin) resection and survival to date., Case Presentation: Case 1: A 53-year-old man was diagnosed with pancreatic adenocarcinoma (Stage III). He received six cycles of PD-1 antibody plus chemotherapy as the first-line treatment. The tumor was reduced from 11.8×8.8 cm to "0" (the pancreatic head was normal as shown by enhanced computed tomography, ECT) after preoperative neoadjuvant therapy (PNT) and the adverse effects were tolerable. The patient underwent radical surgery and achieved R0 resection. Case 2: A 43-year-old man diagnosed with pancreatic adenocarcinoma with liver metastasis (Stage IV) received three cycles of PD-1 antibody combined with chemotherapy. The tumor was reduced from 5.2×3.9 cm to 2.4×2.3 cm with no side effects. The patient also underwent radical surgery and achieved R0 resection., Conclusion: PD-1 antibody plus a chemotherapy regimen resulted in a surprising curative effect and safety in two patients with UAPC, which may portend an improvement in pancreatic carcinoma treatment. We may have a way for UAPC patients to obtain radical treatment and gain long-term survival. Two PD-L1 positive UAPC patients with microsatellite stability (MSS) enlighten us to have a more comprehensive understanding of the prediction of immunotherapy., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Shang, Li, Fan, Zhao, Niu, Bian, Yuan, Kong, Zhu, Xu, Dong and Xiang.)

An N-heterocyclic carbene-catalyzed formal [5 + 5] reaction between enals and furanones that generates multisubstituted coumarins in a single step is reported. Five atoms in each of the substrates are involved in this catalytic process to form a benzene and a lactone ring. The power of the method is further demonstrated in metal-free total syntheses of several natural products (defucogilvocarcins M, E, and V) bearing coumarin as the key structural motif.

A highly enantioselective method for quick access to dihydrocoumarins is reported. The reaction involves a cooperative catalytic process with carbene and in situ generated Brønsted acid as the catalysts. α-Chloro aldehyde and readily available and stable o-hydroxybenzhydryl amine substrates were used to generate reactive azolium ester enolate and ortho-quinone methide (o-QM) intermediates, respectively, to form dihydrocoumarins with exceptionally high diastereo- and enantioselectivities. The catalytic reaction products can be easily transformed to valuable pharmaceuticals and bioactive molecules.

An N-heterocyclic carbene (NHC) catalyzed domino reaction triggered by a δ-LUMO activation of α,β-γ,δ-diunsaturated enal has been developed for the formal [4 + 2] construction of multisubstituted arenes and 3-ylidenephthalide. These two products, formed in a highly chemo- and regioselective manner, were obtained via different catalytic pathways due to a simple change of the substrate. The activation of the remote δ-carbon of unsaturated aldehydes expands the synthetic potentials of NHC organocatalysis.