Dynamic Kinetic Activation of Aziridines Enables Radical-Polar Crossover (4 + 3) Cycloaddition with 1,3-Dienes.

The cycloaddition of aziridines with unsaturated compounds is a valuable method for synthesizing nitrogen heterocycles. However, this process is predominantly substrate-controlled, posing significant challenges in regulating the regioselectivity of the C-N bond cleavage. In this study, we report a nickel-catalyzed dynamic kinetic activation strategy that enables catalyst-controlled activation of aziridines.

Vortex bifocusing of extreme ultraviolet using modified Fermat-spiral photon-sieve splitter.

Structured beams carrying orbital angular momentum (OAM) provide powerful capabilities for applications in optical tweezers, super-resolution imaging, quantum optics, and ad-vanced microparticle manipulation. However, it is challenging for generate and control the OAM beams at the extreme ultraviolet (EUV) region due to the lack of suitable wave front shaping optics arise from being limited to the strong absorption of most materials. Here, we use a modified Fermat-spiral photon-sieve splitter to simultaneously generate two focused doughnut beams with opposite helical phase.

Unlocking regioselective meta-alkylation with epoxides and oxetanes via dynamic kinetic catalyst control.

Regioselective arene C-H bond alkylation is a powerful tool in synthetic chemistry, yet subject to many challenges. Herein, we report the meta-C-H bond alkylation of aromatics bearing N-directing groups using (hetero)aromatic epoxides as alkylating agents. This method results in complete regioselectivity on both the arene as well as the epoxide coupling partners, cleaving exclusively the benzylic C-O bond.

A controllable gelatin-based microcarriers fabrication system for the whole procedures of MSCs amplification and tissue engineering.

Biopolymer microbeads present substantial benefits for cell expansion, tissue engineering, and drug release applications. However, a fabrication system capable of producing homogeneous microspheres with high precision and controllability for cell proliferation, passaging, harvesting and downstream application is limited. Therefore, we developed a co-flow microfluidics-based system for the generation of uniform and size-controllable gelatin-based microcarriers (GMs) for mesenchymal stromal cells (MSCs) expansion and tissue engineering.

Effects of ECM proteins (laminin, fibronectin, and type IV collagen) on the biological behavior of Schwann cells and their roles in the process of remyelination after peripheral nerve injury.

It is important to note that complete myelination and formation of myelinated fibers are essential for functional nerve regeneration after peripheral nerve injury (PNI). However, suboptimal myelin regeneration is common and can hinder ideal nerve regeneration. Therefore, it is important to closely monitor and support myelin regeneration in patients with PNI to achieve optimal outcomes.

Nickel-Catalyzed Sodium Hypophosphite-Participated Direct Hydrophosphonylation of Alkyne toward -Phosphinates.

The traditional methods for the synthesis of phosphinate esters use phosphorus trichloride (PCl) as the phosphorous source, resulting in procedures that are often highly polluting and energy intensive. The search for an alternative approach that is both mild and environmentally friendly is a challenging, yet highly rewarding task in modern chemistry. Herein, we use an inorganic phosphorous-containing species, NaHPO, to serve as the source of phosphorous that participates directly in the nickel-catalyzed selective alkyne hydrophosphonylation reaction.

Carbonylative C-C Bond Activation of Aminocyclopropanes Using a Temporary Directing Group Strategy.

Temporary directing groups (TDGs) underpin a range of C-C bond activation methodologies; however, the use of TDGs for the regiocontrolled activation of cyclopropane C-C bonds is underdeveloped. In this report, we show how an unusual ring contraction process can be harnessed for TDG-based carbonylative C-C bond activations of cyclopropanes. The method involves the transient installation of an isocyanate-derived TDG, rather than relying on carbonyl condensation events as used in previous TDG-enabled C-C bond activations.

Rhodacyclopentanones as Linchpins for the Atom Economical Assembly of Diverse Polyheterocycles.

We outline a conceptual blueprint that provides direct and atom economical access to a wide range of complex polyheterocycles. Our method capitalizes on the ambiphilic reactivity of rhodacyclopentanones that arise upon exposure of cyclopropanes to Rh(I) catalysts and CO. Using this approach, a wide array of polycyclizations are achieved, including variants that involve powerful dearomatizations and medium ring formations.

Circular RNA expression pattern in cisplatin-resistant osteosarcoma cells.

Background: Cisplatin resistance associated with circular RNA (circRNA) in osteosarcoma (OS) is not fully understood. The present study aimed to reveal the expression profile of circRNAs related to cisplatin resistance in OS.

Methods: Cisplatin-resistant OS cell lines (U2OS-R and MG63-R) were induced using different concentrations of cisplatin and RNA sequencing (RNA-seq) was performed to screen differentially expressed circRNAs in these cells.

Modular Access to Eight-Membered N-Heterocycles by Directed Carbonylative C-C Bond Activation of Aminocyclopropanes.

Aminocyclopropanes equipped with pendant nucleophiles undergo carbonylative heterocyclization triggered by C-C bond activation to generate eight-membered N-heterocycles. In these processes, intramolecular "capture" of a rhodacyclopentanone intermediate by an aryl or N-based nucleophile is followed by C-C or C-N bond-forming "collapse" to the targets. These studies demonstrate how the combination of cyclopropane strain release and the templating effect of catalytically generated metallacycles can be harnessed to enable otherwise challenging medium ring closures.

Modular Access to Azepines by Directed Carbonylative C-C Bond Activation of Aminocyclopropanes.

A modular Rh-catalyzed entry to azepines is outlined. Under a CO atmosphere, protecting group directed C-C bond activation of aminocyclopropanes provides rhodacyclopentanones. These intermediates are effective for intramolecular C-H metalation of either an N-aryl or N-vinyl unit en route to azepine ring systems.

New Initiation Modes for Directed Carbonylative C-C Bond Activation: Rhodium-Catalyzed (3 + 1 + 2) Cycloadditions of Aminomethylcyclopropanes.

Under carbonylative conditions, neutral Rh(I)-systems modified with weak donor ligands (AsPh or 1,4-oxathiane) undergo N-Cbz, N-benzoyl, or N-Ts directed insertion into the proximal C-C bond of aminomethylcyclopropanes to generate rhodacyclopentanone intermediates. These are trapped by N-tethered alkenes to provide complex perhydroisoindoles.

[Clinical research of needle-pricking therapy for functional retrograde ejaculatioin].

Objective: To observe the clinical effects of needle-pricking therapy, a newly medical and minimally invasive technique, for functional retrograde ejaculation and to explore its mechanism. Methods Thirty-six patients with functional retrograde ejaculation were randomly divided into an observation group(19 cases) and a control group(17 cases) In the observation group,needle-pricking therapy was used at Guanyuan(CV 4) and bilateral sacral plexus nerve,lumbar 1 nerve and greater occipital nerve stimulating points,once a week. In the control group, midodrine tablets were prescribed orally,three times a day.

Cu-Catalyzed selective cascade sp(3) C-H bond oxidative functionalization towards isoxazoline derivatives.

The first Cu-catalyzed cascade sp(3) C-H bond oxidative functionalization of the 2-ethylazaarenes has been developed. The two different sp(3) C-H bonds in 2-ethylazaarenes are selectively oxidized and four new types of bonds (C=O, C=N, C-C, C-O) are constructed in one operation. Starting from the simple substrates and cheap nitro source, this reaction provides an efficient approach to produce new kinds of isoxazolines.

Enantioselective synthesis of arylglycine derivatives by direct C-H oxidative cross-coupling.

A new method for the synthesis of chiral α-amino acid derivatives by enantioselective C-H arylation of N-aryl glycine esters with aryl boric acids in the presence of a chiral Pd(II)-catalyst has been developed. This work successfully integrates the direct C-H oxidation with asymmetric arylation and exhibits excellent enantioselectivity.

A unique copper-catalyzed cross-coupling reaction by hydrogen (H2) removal for the stereoselective synthesis of 3-phosphoindoles.

The first Cu(i)-catalyzed cross-coupling reaction by hydrogen (H2) removal for the stereoselective synthesis of 3-phosphoindoles is reported. Going beyond the oxidative dehydrogenative coupling reactions reported recently, this reaction completely omits the oxidant and base, producing hydrogen (H2) as the only byproduct.

Regio- and stereoselective allylic C-H arylation with electron-deficient arenes by 1,1'-bi-2-naphthol-palladium cooperation.

A palladium-catalyzed allylic C-H arylation reaction with electron-deficient arenes with high regio- and stereoselectivity is reported. This work represents the first successful use of 1,1'-bi-2-naphthol as the ancillary ligand in allylic C-H activation, which is the key factor for chemoselectivity. Furthermore, high selectivity allylic C-H acetoxylation and amination were also successfully achieved under the same catalytic system.

Pd(II)-catalyzed C(sp2)-H hydroxylation with R2(O)P-coordinating group.

A novel R2(O)P-directed Pd(II)-catalyzed C-H hydroxylation to synthesize various substituted 2'-phosphorylbiphenyl-2-ol compounds is described. Notably, the reaction operates under mild conditions and shows good functional group tolerance, high selectivity, and yield.

Palladium-catalyzed sp2 and sp3 C-H bond activation and addition to isatin toward 3-hydroxy-2-oxindoles.

The first Pd(II)-catalyzed C-H addition to isatins by direct sp(2)/sp(3) C-H bond activation for the construction of 3-substituted-3-hydroxy-2-oxindoles is reported. The bidentate nitrogen ligands were found to promote this reaction. Specifically, the preliminary bioassay indicated that 3-(5-chlorobenzoxazole)-3-hydroxy-N-benzyl-2-oxindole (2w) is a new inhibitor of human kidney cancer and hepatocellular carcinoma cells.

Silver catalyzed intramolecular cyclization for synthesis of 3-alkylideneoxindoles via C-H functionalization.

A novel protocol for the preparation of various 3-alkylideneoxindoles via a silver-catalyzed aromatic C-H functionalization has been developed. The process is simple, environmentally conscious, and avoids the use of abundant bases, oxidants, or other additives.

Unexpected domino reaction via Pd-catalyzed Sonogashira coupling of benzimidoyl chlorides with 1,6-enynes and cyclization to synthesize quinoline derivatives.

A domino reaction via palladium-catalyzed Sonogashira coupling of benzimidoyl chlorides with 1,6-enynes and then cyclization to form quinoline derivatives has been developed. The reaction conditions and the scope of the process are examined, and a plausible mechanism is proposed. The procedure is simple, rapid, and general, and the substrates are readily available.