A water mediated multicomponent reaction for the synthesis of novel spirooxindole derivatives and their antifungal activity.

A water mediated three-component reaction of isatin, 4-aminocoumarin, and 1,3-cyclodicarbonyl compounds is reported for the synthesis of spiro[chromeno[4,3-]cyclopenta[]pyridine-7,3'-indoline]trione and the spiro[chromeno[4,3-]quinoline 7,3'-indoline]trione. Up to 27 different spirooxindole derivatives were synthesized by this method. The bioactivity of these spirooxindole derivatives was evaluated and they were found to show antifungal activity against , , , and .

Stimuli-triggered multilayer films in response to temperature and ionic strength changes for controlled favipiravir drug release.

The block copolymer micelles and natural biopolymers were utilized to form layer-by-layer (LbL) films via electrostatic interaction, which were able to effectively load and controllably release favipiravir, a potential drug for the treatment of coronavirus epidemic. The LbL films demonstrated reversible swelling/shrinking behavior along with the manipulation of temperature, which could also maintain the integrity in the structure and the morphology. Due to dehydration of environmentally responsive building blocks, the drug release rate from the films was decelerated by elevating environmental temperature and ionic strength.

Polydentate hydrazones as multitasking catalysts in visible-light-induced coupling reactions of amines.

A Cu/hydrazone catalyst has been applied in the coupling reactions of anilines for the synthesis of diarylamines and azobenzenes. The copper complex that is formed plays a double duty by harnessing photon energy as a photocatalyst and then by catalysing organometallic elementary steps as a transition metal catalyst. By the selection of hydrazones and bases, the reaction selectivity of aniline can be tuned between homo-coupling and its cross-coupling with arylboronic acid, exhibiting the great potential of such hydrazones in organic synthesis.

Ligand-enabled Ni-catalyzed hydroarylation and hydroalkenylation of internal alkenes with organoborons.

The transition metal-catalyzed hydrofunctionalization of alkenes offers an efficient solution for the rapid construction of complex functional molecules, and significant progress has been made during last decades. However, the hydrofunctionalization of internal alkenes remains a significant challenge due to low reactivity and the difficulties of controlling the regioselectivity. Here, we report the hydroarylation and hydroalkenylation of internal alkenes lacking a directing group with aryl and alkenyl boronic acids in the presence of a nickel catalyst, featuring a broad substrate scope and wide functional group tolerance under redox-neutral conditions.

Steric Effects in the Deposition Mode and Drug-Delivering Efficiency of Nanocapsule-Based Multilayer Films.

Using surface-initiated atom transfer radical polymerization (ATRP), block polymers with a series of quaternization degrees were coated on the surface of silica nanocapsules (SNCs) by the "grafting-from" technique. Molnupiravir, an antiviral medicine urgently approved for the treatment of SARS-CoV-2, was encapsulated in polymer-coated SNCs and further incorporated into well-defined films with polystyrene sulfonate (PSS) homopolymers by layer-by-layer (LBL) self-assembly via electrostatic interactions. We investigated the impact of the quaternization degree of the polymers and steric hindrance of functional groups on the growth mode, swelling/deswelling transition, and drug-delivering efficiency of the obtained LBL films.

Heterogeneous copper-catalyzed synthesis of diaryl sulfones.

A carbon-supported copper nanoparticle (Cu-NP) with high catalytic activity for the synthesis of diaryl sulfones is reported. For the first time, this Cu-NP is proved to be able to effectively promote the reaction of arylboronic acids and arylsulfonyl hydrazides to generate diaryl sulfones at room temperature. The reaction shows excellent substrate universality, and substrates with different substituents can undergo the reaction smoothly, leading to the desired products in good yields.

Construction of α-Amino Azines via Thianthrenation-Enabled Photocatalyzed Hydroarylation of Azine-Substituted Enamides with Arenes.

α-Amino azines are widely found in pharmaceuticals and ligands. Herein, we report a practical method for accessing this class of compounds via photocatalyzed hydroarylation of azine-substituted enamides with the in situ-generated aryl thianthrenium salts as the radical precursor. This reaction features a broad substrate scope, good functional group tolerance, and mild conditions and is suitable for the late-stage installation of α-amino azines in complex structures.

Vinyl Sulfonium Salts as the Radical Acceptor for Metal-Free Decarboxylative Alkenylation.

Vinyl sulfonium salts typically act as an electrophilic Michael acceptor, thus initiating many tandem cyclization reactions. Herein, we disclosed the novel reactivity of vinyl sulfonium salts as a radical acceptor. Using redox-active ester as an alkyl radical precursor, metal-free decarboxylative alkenylation with vinyl sulfonium salts was realized using eosin Y as a photocatalyst.

Synthesis of α-functionalized ketones by visible-light promoted oxygenation of alkenes.

This article gives a short review on the visible-light promoted synthesis of α-functionalized ketones from alkenes. Various α-functionalized ketones, including α-halo, sulfinyl/sulfonyl, aryl, azido and thiocyanato ketones can be synthesized from the reaction of alkenes with different radical species generated by visible-light catalysis. These transformations typically use dioxygen as the terminal oxidant and do not require a transition metal to activate the double bond, which is quite different from the transition-metal catalysed reactions (Wacker oxidation or hydroformylation).

Ynamide Smiles Rearrangement Triggered by Visible-Light-Mediated Regioselective Ketyl-Ynamide Coupling: Rapid Access to Functionalized Indoles and Isoquinolines.

In the past decades, significant advances have been made on radical Smiles rearrangement. However, the eventually formed radical intermediates in these reactions are limited to the amidyl radical, except for the few examples initiated by a N-centered radical. Here, a novel and practical radical Smiles rearrangement triggered by photoredox-catalyzed regioselective ketyl-ynamide coupling is reported, which represents the first radical Smiles rearrangement of ynamides.

Electrostatically Assembled Multilayered Films of Biopolymer Enhanced Nanocapsules for on-Demand Drug Release.

We describe layer-by-layer (LbL) buildup and pH-responsive behavior of multilayer films of alginate/chitosan/alginate -modified silica nanocapsules (SNCs) and chitosan (CS) biopolymers via electrostatic interaction. The SNC/CS films exhibit pH-triggered swelling/deswelling transitions under physiological conditions. Fulvestrant, an FDA-approved selective estrogen receptor down-regulator agent for the treatment of breast cancer, was encapsulated in SNCs and further incorporated into the LbL films.

Visible-light promoted aerobic difunctionalization of alkenes with sulfonyl hydrazides for the synthesis of β-keto/hydroxyl sulfones.

A practical method has been developed for the conversion of alkenes to β-keto/hydroxyl sulfones by their reaction with sulfonyl hydrazides under metal-free conditions. This reaction proceeds through the oxidative addition of alkenes by sulfonyl radicals that are generated by visible-light induced oxidation of sulfonyl hydrazides. Notaly the reaction uses O2 as the terminal oxidant, instead of metal catalysts or oxidants like TBHP, leading to H2O and N2 as the clean by-products.

Facile synthesis of α-alkoxyl amides scandium-catalyzed oxidative reaction between ynamides and alcohols.

A novel and efficient scandium-catalyzed oxidative reaction between ynamides and alcohols for the facile synthesis of various α-alkoxyl amides is reported in this paper. The reaction avoids the need for the use of α-diazo carbonyls which are unstable and may cause some safety concerns. Instead, by using alkynes as the starting materials, this protocol features readily available substrates, compatibility with a broad range of functional groups, simple procedure, mild reaction conditions, and high chemoselectivity.

Identification of a pyridine derivative inducing senescence in ovarian cancer cell lines via P21 activation.

Cellular senescence is a state of irreversible cell growth arrest. Increasing evidence suggests that cellular senescence contribute to tumour suppression in vivo. However, only a few anti-cancer drugs have been discovered to induce cellular senescence.

Synthesis of α,β-Unsaturated Amidines through Gold-Catalyzed Intermolecular Reaction of Azides with Ynamides.

A concise and flexible synthesis of α,β-unsaturated amidines via gold-catalyzed intermolecular ynamide amination/carbene 1,2-shift between ynamides and benzylic azides has been developed. Under mild reaction conditions, various α,β-unsaturated amidines were obtained in mostly good yields, thus providing an efficient and atom-economic way for the construction of valuable α,β-unsaturated amidines.

Dual gold/photoredox-catalyzed bis-arylative cyclization of chiral homopropargyl sulfonamides with diazonium salts: rapid access to enantioenriched 2,3-dihydropyrroles.

A novel dual gold/photoredox-catalyzed bis-arylative cyclization of chiral homopropargyl sulfonamides with diazonium salts has been developed, allowing the facile synthesis of various enantioenriched 2,3-dihydropyrroles in generally moderate to good yields with excellent enantioselectivities under very mild conditions without using any strong oxidants. The reaction is proposed to undergo an Au/Au redox cycle promoted by visible-light photoredox catalysis.

Visible-Light Photocatalytic Aerobic Annulation for the Green Synthesis of Pyrazoles.

A selective and high yielding synthesis of polysubstituted pyrazoles through a VLPC (visible light photoredox catalysis)-promoted reaction of hydrazine with Michael acceptors is reported. The method employs very mild reaction conditions and uses air as the terminal oxidant, which makes the process environmentally benign. Different types of Michael acceptors with various substituents can undergo the reaction to afford corresponding pyrazoles in good to excellent yields.

Correction: A mild and facile synthesis of polyfunctionalized pyridines: merging three-component cyclization and aerobic oxidation by amine/metal catalysts.

Correction for 'A mild and facile synthesis of polyfunctionalized pyridines: merging three-component cyclization and aerobic oxidation by amine/metal catalysts' by Chunyin Zhu et al., Org. Biomol.

Correction: Ylide formal [4 + 1] annulation.

Correction for 'Ylide formal [4 + 1] annulation' by Chunyin Zhu et al., Org. Biomol.

A mild and facile synthesis of polyfunctionalized pyridines: merging three-component cyclization and aerobic oxidation by amine/metal catalysts.

A mild and facile synthesis of polyfunctionalized pyridines from NH4OAc, β,γ-unsaturated α-ketoesters, and ketones/aldehydes has been reported through tandem three-component cyclization and aerobic oxidation using the combination of amine and metal catalysts. The synthetic value of the developed methodology was demonstrated by a gram-scale reaction and a wide range of substrates including naturally occurring citronellal.

Recent Progress towards Transition-Metal-Catalyzed Synthesis of Fluorenes.

Fluorenes are a commonly encountered structural motif in materials science, pharmaceutical chemistry, and organic synthesis. Among various strategies towards the synthesis of this unique structure, transition metal-catalyzed functionalization has emerged as one of the most efficient methods. This Minireview presents an overview of the recent advances in this emerging area by highlighting the reactions' specificity and applicability and, where possible, provides a mechanistic rationale.

Ylide formal [4 + 1] annulation.

Over the past few decades, ylide chemistry has been significantly extended to an area beyond olefination and small ring formation, among which ylide [4 + 1] annulation has been extensively explored, and five-membered ring structures, such as dihydrofurans, isoxazolines, pyrrolines, indoles, dihydropyrazoles and cyclopentenones, can be readily constructed through this type of transformation. An overview of the recent advances in this field is presented herein. Ylide [4 + 1] annulations are reviewed by highlighting their product diversity, selectivity and applicability, and the mechanistic rationale is presented when possible.

Synthesis, cytotoxicity for mimics of catalase: inhibitors of lactate dehydrogenase and hypoxia inducible factor.

Lactate dehydrogenase A (LDH-A) is a potentially important metabolic target for the inhibition of the highly activated glycolysis pathway in cancer cells. Two Mn(II) complexes with ligand containing di(pyridylmethyl) amine and pyrrol-ketone were used to attenuate the activity of LDH-A. The inhibition of the manganese(II) complexes on the proliferation of HepG-2 cells is related to their ability to disproportionate H2O2.

Wacker-type oxidation of internal alkenes using Pd(Quinox) and TBHP.

The Pd-catalyzed TBHP-mediated Wacker-type oxidation of internal alkenes is reported. The reaction uses 2-(4,5-dihydro-2-oxazolyl)quinoline (Quinox) as ligand and TBHP(aq) as oxidant to deliver single ketone constitutional isomer products in a predictable fashion from electronically biased olefins. This methodology is showcased through its application on an advanced intermediate in the total synthesis of the antimalarial drug artemisinin.