Chelation-Induced Zwitterion-like Antifouling Behavior on Anionic Poly(3,4-ethylenedioxythiophene) Surfaces.

Antifouling properties are crucial for enhancing the longevity and functionality of biomedical implants, drug delivery systems, and biosensors. Zwitterionic polymers are renowned for their exceptional surface hydration and charge neutrality, which effectively resist biomolecular adsorption and protein attachment. We propose an innovative approach to develop zwitterion-like antifouling surfaces by chelating divalent cations with anionic poly(3,4-ethylenedioxythiophene) (PEDOT) films, specifically PEDOT-PO4 and PEDOT-COOH. The chelation behavior of these films was systematically evaluated using Na+, Mg2+, and Ca2+ ions. Divalent ions, particularly Ca2+ and Mg2+, exhibit a strong affinity for the anionic groups, leading to significant antifouling properties. These modified surfaces effectively repelled both negatively charged bovine serum albumin (BSA) and positively charged lysozyme (LYZ) proteins across various pH environments. This study offers valuable insights into the antifouling characteristics of charged surfaces, enhancing our understanding of how ion-mediated surface modifications influence protein adsorption and interactions.

Photocatalytic Oxidative Cleavage of Alkenes by Molecular Oxygen: Reaction Scope, Mechanistic Insights, and Flow Application.

The oxidative cleavage of C═C bonds with molecular oxygen was promoted effectively by a catalytic amount of a decatungstate photocatalyst using black light irradiation (365 nm). Not only aromatic ketones but also aliphatic ketones were obtained by the photocatalytic protocol. The continuous flow reaction of α-methylstyrene using a high-power ultraviolet light-emitting diode (365 nm) dramatically decreased the reaction time.

Electron-Transfer Protocol for the Hydroxyalkenylation of Alkenes Using 1,2-Bis(phenylsulfonyl)ethylene.

We report a protocol for alkene hydroxyalkenylation. Using a persulfate anion as a one-electron-oxidation reagent and 1,2-bis(phenylsulfonyl)ethylene as a radical acceptor in the presence of water, alkenes were converted into the corresponding 1-phenylsulfonyl-4-hydroxyalkenes in good to high yields. The hydroxyalkenylation process involves the nucleophilic hydroxylation of alkene radical cations to give ß-hydroxyalkyl radicals, which, after a radical addition/ß-elimination sequence, provide the products. We also report a photocatalytic protocol for alkoxyalkenylation.

Photoinduced arylation of chloroarenes in flow: synthesis of unsymmetrical biaryls.

A photoflow method is presented for a radical-based coupling of unactivated arenes and aryl chlorides. The process proceeded smoothly at ambient temperature under metal-free conditions. Of note is that the reaction conditions are fine-tuned for chloroarenes with different electronic properties. While the reactivity profile of aryl chlorides is generally known to be inferior to those of the corresponding iodides and bromides, we demonstrate that the title protocol is efficient in converting readily available and inexpensive chloroarenes into unsymmetrical biaryl products.

Total synthesis of (±)-mersicarpine following a 6-exo-trig radical cyclization.

Described is a total synthesis of racemic mersicarpine from diethyl 4-oxopimelate. The synthetic route takes advantage of a 2-indolyl radical cyclization to construct the pyrido[1,2-a]indole scaffold bearing the all-carbon quaternary stereocenter.

Site-Selective Alkenylation of Unactivated C(sp3 )-H Bonds Mediated by Compact Sulfate Radical.

A broad variety of unactivated acyclic and alicyclic substrates cleanly undergo site-selective alkenylation of unactivated C(sp3 )-H bonds with 1,2-bis(phenylsulfonyl)ethene in the presence of persulfate. This simple transformation furnishes (E)-2-alkylvinylphenylsulfones in up to 88 % yield. In contrast with the previously reported decatungstate protocol, the current method is applicable to alkenylation of sterically hindered C-H bonds. This important advantage significantly broadens the substrate scope, and is attributed to the compact size of the sulfate radical employed in the C-H activation and cleavage.

Rapid construction of tetrahydropyridine scaffolds via formal imino Diels-Alder reactions of Schiff bases and Nazarov reagents.

Described is a one-flask, two-step method for the synthesis of highly functionalized piperidines. The process involves formal [4 + 2] cycloadditions of Schiff bases and Nazarov reagents, followed by facile elaborations of the initial cycloadducts. Notably, these aza-annulations are facilitated by protic solvents and proceed smoothly under ambient conditions, without other additives. The synthetic utility of this annulation protocol is further showcased through a concise, convergent synthesis of (±)-tetrabenazine.

Palladium-Catalyzed α-Allylation of Secondary Nitroalkanes with Allylic Alcohols and Strategic Exploitation of Seebach's Reagent for the Total Synthesis of (±)-Adalinine.

A method is reported for the catalytic direct coupling of allylic alcohols and nitroalkanes. In the allylation process, the synergistic action of palladium complexes and titanium(IV) alkoxide facilitates the formation of nitronate and π-allylpalladium intermediate. In the cases of reluctant allylations, typically with sterically demanding nitroalkanes, we found the addition of substoichiometric amount of DBU greatly facilitates the desired transformation. We also accomplished a total synthesis of (±)-adalinine through a homoallyl nitroalkane derived from Seebach's reagent.

Temperature-Controlled Thiation of α-Cyano-ß-Alkynyl Carbonyl Derivatives for De Novo Synthesis of 2-Aminothiophenes and Thieno[2,3- c]isothiazoles.

Making use of temperature-controlled thiation as a key operation, a simple route to 2-aminothiophenes or thieno[2,3- c]isothiazoles has been newly developed wherein the 2-aminothiophene nucleus was formed through an initial formation of thioamide followed by a 5-exo-dig addition to the tethered alkyne; however, under harsher thermal conditions, excess sulfur-transferring reagents enabled further oxidative thiation to generate the corresponding thieno[2,3- c]isothiazoles.

EPR Imaging Spin Probe Trityl Radical OX063: A Method for Its Isolation from Animal Effluent, Redox Chemistry of Its Quinone Methide Oxidation Product, and in Vivo Application in a Mouse.

We report herein a method for the recovery, purification, and application of OX063, a costly, commercially available nontoxic spin probe widely used for electron paramagnetic resonance (EPR) imaging, as well as its corresponding quinone methide (QM) form. This precious probe can be successfully recovered after use in animal model experiments (25-47% recovery from crude lyophilizate with 98.5% purity), even from samples that are >2 years old. Significantly, the recovered trityl can be reused in further animal model EPR imaging experiments. The work also describes support for the observed formation of an air-sensitive radical derived from the QM under reducing conditions.

Experimental and computational studies on interrupted Nazarov reactions: exploration of umpolung reactivity at the α-carbon of cyclopentanones.

A set of densely substituted, α-functionalized cyclopentanones can be generated by a two-component, domino reaction sequence entailing the Nazarov electrocyclization of divinyl ketones and nucleophilic addition of the resulting 2-oxidocyclopentenyl cations by selected trapping modalities. Bypassing the typical eliminative termination, Nazarov oxyallyl species can react with carbon π-nucleophiles through cycloadditions (or formal cycloadditions), in which bridged bicyclic systems are established, or nucleophilic trappings whereby one terminal carbon of the oxyallyl intermediate is subjected to carbon-carbon bond formation. A detailed investigation of reaction parameters to explicitly control the course of the "interrupted" Nazarov reactions is described. This methodology allows for facile installation of α-quaternary centers bearing allyl, alkynyl, and heteroaryl groups in an umpolung fashion. In addition, the trapping event of a Nazarov intermediate with furan was studied by DFT computations, in conjunction with experimental data, offering a rationale for the observed reaction pattern and diastereoselectivity.

A Concise Route to Keto-Bridged Polyphenols by Photo-Fries Rearrangement in Flow.

Described is a new synthetic route to bis(2-hydroxy-3,5-di-t-butylphenyl)methanone and its derivatives. The combined esterification/photo-Fries rearrangement approach enables a modular preparation of keto-bridged polyphenols. This protecting group-free process is highly atom- and step-economic, and a scalable production was easily achieved in the continuous-flow mode.

Coordination Chemistry and Reactivity of a Lewis Acidic Di-Zinc Framework Supported by Bisphenoxymethanone Ligands.

We present the synthesis, structural characterization, and reactivity studies of a tetra-zinc complex supported by the bisphenoxymethanone ligands and its transformation into various di-zinc architectures. Our findings highlight the potential of these complexes in molecular recognition, supramolecular chemistry, and catalysis.

Haloarene-guided cascade arylation of cyclic vinylogous esters under palladium catalysis.

A method is presented for the synthesis of diaryl cyclic vinylogous esters. The sequence of C(sp3)-H arylation events is programed under the differentiated reactivity of the aryl halides, and the optimized reaction system is effectively diverted from producing dihomo-arylated products. The site selectivity of the second arylation is notably modulated by the substitution pattern of the substrates.

Brønsted acid-mediated Nazarov cyclization of vinylallenes.

Treatment of siloxy enynes with base leads to the corresponding vinylsiloxyallenes which undergo Nazarov cyclization in the presence of trifluoroacetic acid to provide the cyclized product as a mixture of regioisomers in moderate to good overall yield.

Photo-Fries rearrangement in flow under aqueous micellar conditions.

A flow edition of photo-Fries rearrangement for the synthesis of 2-acylphenols in an aqueous micellar medium has been described. We take advantage of a narrow channel reactor and micelle-induced confinement effect to refine both the efficiency and selectivity of the parent photoreaction.

Palladium-catalyzed α-arylation of indolin-3-ones.

A method for the catalytic α-arylation of indolin-3-ones was developed. The catalytic system comprising Pd(dba)2 and PAd3 was found to be optimal for the transformation. The protocol features broad functional group compatibility in that a range of arylated indoxyl derivatives bearing a fully substituted carbon center was synthesized with high efficiency. A preliminary bioassay study revealed that the selected indole-substituted indolin-3-ones exhibit favorable cytotoxic activities against HCT-116 cancer cell line.

Palladium-catalyzed N1-selective allylation of indoles with allylic alcohols promoted by titanium tetraisopropoxide.

The direct N1-selective allylation of indoles with allylic alcohols has been accomplished by synergistic functions of palladium catalysts and titanium tetraisopropoxide. The site selectivity is notably different from that observed in other related transition metal-catalyzed approaches. This chemistry provides a facile route to a variety of allylated indoles in synthetically useful yields. The utility of this simple allylation reaction was demonstrated with the first total synthesis of (+)-N-(4'-hydroxyprenyl)-cyclo(alanyltryptophyl), which was completed in five steps, starting from l-tryptophan methyl ester hydrochloride.

Palladium-Catalyzed Cascade Arylation of Vinylogous Esters Enabled by Tris(1-adamantyl)phosphine.

Described is a method for the transformation of a cyclic vinylogous ester to the corresponding polyarylated product. We found a catalytic system comprising palladium diacetate and tris(1-adamantyl)phosphine is quite effective in promoting a set of controlled cascade arylations. As a result, a range of novel (hetero)aryl-containing scaffolds was synthesized with a high level of efficiency.

Total syntheses of (+/-)-montanin A and (+/-)-teuscorolide.

The first total syntheses of (+/-)-montanin A and (+/-)-teuscorolide have been achieved from an advanced precursor previously developed via a Diels-Alder strategy; in the synthetic sequence, the synthesis of montanin A was first accomplished in 8 steps, from which teuscorolide was readily achieved in 2 steps by using a novel furan oxidative cyclization-retro-cyclization process as a key operation.