The Cytochalasins and Polyketides from a Mangrove Endophytic Fungus QYF.

Twelve compounds, including four undescribed cytochalasins, xylariachalasins A-D (-), four undescribed polyketides (-), and four known cytochalasins (-), were isolated from the mangrove endophytic fungus QYF. Their structures and absolute configurations were established by extensive spectroscopic analyses (1D and 2D NMR, HRESIMS), electronic circular dichroism (ECD) calculations, C NMR calculation and DP4+ analysis, single-crystal X-ray diffraction, and the modified Mosher ester method. Compounds and are rare cytochalasin hydroperoxides.

Hydrosilylation of Arynes with Silanes and Silicon-Based Polymer.

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.

Direct Arylation of Silicon Nanocrystals with Hexadehydro-Diels-Alder-Derived Benzynes.

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.

Carbene-catalyzed [3 + 2 + 1] annulation C-N radical coupling of iminyl radicals and ketyl radicals.

An N-heterocyclic carbene-catalyzed cascade [3 + 2 + 1] annulation to assemble vinyl azides, aldehydes, and trihalomethyl reagents (Togni's reagent or CCl) towards 1,3-oxazin-6-ones was reported. The cascade was triggered by an NHC-catalyzed single electron transfer (SET) between aldehydes and trihalomethyl reagents, followed by the addition of trihalomethyl radicals to vinyl azides, a denitrogenated transformation into iminyl radicals, a C-N radical coupling of iminyl radicals and ketyl radicals, and a base-controlled dehalogenative cyclization.

Case report: Two PD-L1 positive unresectable advanced pancreatic carcinoma patients with microsatellite stability achieved R0 resection after PD-1 antibody plus chemotherapy as a successful downstaging therapy: A report of two cases.

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.

Electroredox carbene organocatalysis with iodide as promoter.

Oxidative carbene organocatalysis, inspired from Vitamin B1 catalyzed oxidative activation from pyruvate to acetyl coenzyme A, have been developed as a versatile synthetic method. To date, the α-, β-, γ-, δ- and carbonyl carbons of (unsaturated)aldehydes have been successfully activated via oxidative N-heterocyclic carbene (NHC) organocatalysis. In comparison with chemical redox or photoredox methods, electroredox methods, although widely used in mechanistic study, were much less developed in NHC catalyzed organic synthesis.

The eco-friendly electrosynthesis of trifluoromethylated spirocyclic indolines and their anticancer activity.

A method for the electrochemical diastereoselective oxytrifluoromethylation of indoles was developed for the eco-friendly synthesis of CF-containing spirocyclic indolines. The cascade reaction comprised anodic oxidation to obtain CF radicals, the addition of radicals to indoles, and intramolecular spirocyclization. The reaction system without external chemical oxidants could easily be scaled up.

Progress in the Electrochemical Reactions of Sulfonyl Compounds.

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.

Electrochemical synthesis of colloidal lead- and bismuth-based perovskite nanocrystals.

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.

Assembly of multicyclic isoquinoline scaffolds from pyridines: formal total synthesis of fredericamycin A.

The construction of an isoquinoline skeleton typically starts with benzene derivatives as substrates with the assistance of acids or transition metals. Disclosed here is a concise approach to prepare isoquinoline analogues by starting with pyridines to react with β-ethoxy α,β-unsaturated carbonyl compounds under basic conditions. Multiple substitution patterns and a relatively large number of functional groups (including those sensitive to acidic conditions) can be tolerated in our method.

Atroposelective Arene Formation by Carbene-Catalyzed Formal [4+2] Cycloaddition.

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.

Engineering channels of metal-organic frameworks to enhance catalytic selectivity.

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.

Carbene-Catalyzed Desymmetrization and Direct Construction of Arenes with All-Carbon Quaternary Chiral Center.

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.

Stabilized Molybdenum Trioxide Nanowires as Novel Ultrahigh-Capacity Cathode for Rechargeable Zinc Ion Battery.

Exploration of high-performance cathode materials for rechargeable aqueous Zn ion batteries (ZIBs) is highly desirable. The potential of molybdenum trioxide (MoO) in other electrochemical energy storage devices has been revealed but held understudied in ZIBs. Herein, a demonstration of orthorhombic MoO as an ultrahigh-capacity cathode material in ZIBs is presented.

Carbene-catalyzed enantioselective oxidative coupling of enals and di(hetero)arylmethanes.

Di(hetero)arylmethane is a unique structural motif for natural and synthetic functional molecules. To date, it remains challenging to functionalize the diaryl methyl sp3 carbon-hydrogen bond directly in an enantioselective manner. This is likely due to the relatively inert nature of the carbon-hydrogen bond and the difficult enantiofacial discrimination of two sterically similar aryl substituents.

Access to All-Carbon Spirocycles through a Carbene and Thiourea Cocatalytic Desymmetrization Cascade Reaction.

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.

Carbene-Catalyzed Formal [5 + 5] Reaction for Coumarin Construction and Total Synthesis of Defucogilvocarcins.

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.

Carbene and Acid Cooperative Catalytic Reactions of Aldehydes and o-Hydroxybenzhydryl Amines for Highly Enantioselective Access to Dihydrocoumarins.

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.

N-Heterocyclic Carbene-Catalyzed δ-Carbon LUMO Activation of Unsaturated Aldehydes.

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.

Benzene construction via organocatalytic formal [3+3] cycloaddition reaction.

The benzene unit, in its substituted forms, is a most common scaffold in natural products, bioactive molecules and polymer materials. Nearly 80% of the 200 best selling small molecule drugs contain at least one benzene moiety. Not surprisingly, the synthesis of substituted benzenes receives constant attentions.

Indium-mediated asymmetric intramolecular allenylation of N-tert-butanesulfinyl imines: efficient and practical access to chiral 3-allenyl-4-aminochromanes.

An efficient method for the preparation of highly optically active 3-allenyl- and 3-vinyl-4-aminochromanes by In-mediated intramolecular cyclization has been developed. The synthetic utilities of the approach were demonstrated by the construction of various chiral polycyclic heterocycles, especially the interesting spiroheterocyclic compound 9 and steroid analogue 10.

N-Heterocyclic carbene-catalyzed chemoselective cross-aza-benzoin reaction of enals with isatin-derived ketimines: access to chiral quaternary aminooxindoles.

A chemo- and enantioselective cross-aza-benzoin reaction between enals and isatin-derived ketimines is disclosed. The high chemoselectivity (of the acyl anion reaction over enal α- and β-carbon reactions) is enabled by the electronic and steric properties of the N-heterocyclic carbene organocatalyst.

Metal and carbene organocatalytic relay activation of alkynes for stereoselective reactions.

Transition metal and organic catalysts have established their own domains of excellence. It has been expected that merging the two unique domains should provide complimentary or unprecedented opportunities in converting simple raw materials to functional products. N-heterocyclic carbenes alone are excellent organocatalysts.

Access to oxoquinoline heterocycles by N-heterocyclic carbene catalyzed ester activation for selective reaction with an enone.

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.

β-Carbon activation of saturated carboxylic esters through N-heterocyclic carbene organocatalysis.

The activation of the α-carbons of carboxylic esters and related carbonyl compounds to generate enolate equivalents as nucleophiles is one of the most powerful strategies in organic synthesis. We reasoned that the horizons of chemical synthesis could be greatly expanded if the typically inert β-carbons of saturated esters could be used as nucleophiles. However, despite the rather significant fundamental and practical values, direct use of the β-carbons of saturated carbonyl compounds as nucleophiles remains elusive.