Chromium-Catalyzed Radical-Involved Asymmetric Carbonyl Additions.

ConspectusAsymmetric carbonyl addition reactions have long been recognized as a powerful platform for synthesizing chiral alcohols, garnering significant attention in synthetic chemistry. Over the past few decades, notable progress has been made in this field through the use of organometallic reagents and two-electron polar addition processes. However, these approaches often face challenges related to functional group compatibility, particularly when employing strongly basic alkyl nucleophiles, and the construction of vicinal stereocenters remains difficult due to the limited availability of chiral alkylmetal nucleophiles, whether presynthesized or formed .

Ligand-Controlled Chromium Catalysis for Tunable Z/E Selectivity in Asymmetric Homoallylic Alcohol Synthesis.

Chiral homoallylic alcohols with vicinal stereocenters and well-defined Z/E alkene geometries are key structural motifs in bioactive polyketides, yet their efficient and selective synthesis remains a long-standing challenge in asymmetric catalysis. Existing strategies often require preformed organometallic reagents or separate catalytic systems to access different alkene geometries, limiting synthetic efficiency and versatility. Herein, we report a chromium-catalyzed asymmetric reductive coupling of allyl gem-dichlorides with aldehydes, enabling precise and tunable control over regio-, enantio-, diastereo-, and Z/E-selectivity.

Mechanisms of aristolochic acid I Hepatotoxicity: Central role of PDK4-Induced mitochondrial dysfunction and hepatic inflammation.

Aristolochic acids are herbal compound found in many traditional medicines. Among these compounds, AAI is the most frequent and the most toxic, and it could accumulate in water or soil to contaminate our foods, inducing severe toxic effects on human health. Previous research has reported AAI was involved in HCC development mainly by T > A mutation induction.

Iron-Catalyzed Radical Allylic Substitution of Unprotected Allylic Alcohols.

Allylic substitution reactions are essential in organic synthesis, enabling the transformation of allylic reagents into diverse alkenes. Traditional methods, which typically operate through ionic pathways, often require substrate preactivation to address high C─O bond dissociation energies, leading to challenges in regioselectivity and limited substrate compatibility. Here, we introduce an iron-catalyzed radical pathway for allylic substitution that directly activates unprotected allylic alcohols, leveraging the redox and oxophilic properties of low-valent iron to promote selective C─O bond cleavage and allylic transposition.

The characteristics and influencing factors of paramagnetic rim lesions in Chinese MS patients: A 7T MRI study.

Background: Paramagnetic rim lesions (PRLs) in multiple sclerosis (MS) are a significant factor for disability progression and prognosis, but their characteristics in the Chinese population are unclear.

Objective: To explore PRLs in Chinese MS patients using 7T magnetic resonance imaging (MRI), including their number, proportion, distribution, and associated factors.

Methods: Patients from the 7T MRI subgroup of the China National Registry of Neuro-Inflammatory Diseases (CNRID) were prospectively included.

Asymmetric Radical Cyclopropanation of α,β-Unsaturated Amides with α-Boryl and α-Silyl Dibromomethanes via Cr(II)-Based Metalloradical Catalysis.

Transition-metal-catalyzed asymmetric carbene-transfer reactions represent a powerful strategy for synthesizing chiral cyclopropanes. However, current methods predominantly rely on stabilized carbene-bearing -π-conjugated groups, restricting access to less stabilized carbenes, such as -silyl and -boryl carbenes. Herein, we present an unprecedented Cr(II)-based metalloradical system for the asymmetric cyclopropanation of ,-unsaturated amides with -boryl and -silyl dibromomethanes in the presence of Mn as the reducing agent.

Chemical imaging unveils mitochondria as the major site of medicinal biguanide accumulation within cells.

Metformin (MET), a commonly prescribed medication for managing type 2 diabetes, has demonstrated various beneficial effects beyond its primary anti-diabetic efficacy. However, the mechanism underlying MET activity and its distribution within organelles remain largely unknown. In this study, we integrate multiple technologies, including chemical labeling, immunostaining, and high-resolution microscopy imaging, to visualize the accumulation of MET in organelles of cultured cells.

Metallaphotoredox Enabled Single Carbon Atom Insertion into Alkenes for Allene Synthesis.

Efficient methods for synthesizing allenes from readily available starting materials pose a persistent challenge in organic chemistry. In this work, we present a novel two-stage protocol for allene synthesis involving the single-atom insertion into alkenes, facilitated by synergistic photoredox and cobalt catalysis. Diverging from conventional methods such as the Doering-LaFlamme reaction, this photochemical rearrangement approach operates efficiently under mild conditions in a radical-based manner.

Effects of combined use of compound acidifiers and plant essential oils in feed on the reproductive performance and physiological status of Xianjv chickens.

This study investigates the effects of combined compound acidifiers and plant essential oils on the production performance, egg quality, and health parameters of Xianjv chickens. A total of 240 healthy 34-week-old Xianjv chickens were randomly divided into 5 groups and given 5 different feed additives: a control group with a basal diet, and four experimental groups with varying doses of compound acidifiers (CA) and essential oils (EO). The results revealed that the addition of compound acidifiers and essential oils did not significantly affect average daily feed intake, egg production rate, or feed-to-egg ratio.

Pathway plaques and diffusion-weighted lesion analysis after endovascular treatment of unruptured intracranial aneurysms: a prospective study.

Objectives: To evaluate the prevalence and predictors of ischemic lesions on thin-slice DWI (2 mm) in endovascular treatments for unruptured intracranial aneurysms (UIA), particularly explore the potential relationship with pathway plaques.

Methods: Participants eligible for endovascular treatments with UIA at a national stroke center between March 2023 and August 2023 were prospectively enrolled. All participants performed thin-slice DWI (slice thickness of 2 mm) before and after procedures.

FcRn-dependent IgG accumulation in adipose tissue unmasks obesity pathophysiology.

Immunoglobulin G (IgG) is traditionally recognized as a plasma protein that neutralizes antigens for immune defense. However, our research demonstrates that IgG predominantly accumulates in adipose tissue during obesity development, triggering insulin resistance and macrophage infiltration. This accumulation is governed by neonatal Fc receptor (FcRn)-dependent recycling, orchestrated in adipose progenitor cells and macrophages during the early and late stages of diet-induced obesity (DIO), respectively.

0.23-Tesla MRI to differentiate between ischaemic and haemorrhagic strokes within 24 hours of onset: a combined experimental-clinical study.

Background And Purpose: The low-field MRI is a promising tool to accurately diagnose strokes. We here report our study on the accuracy of a 0.23-Tesla (0.

Photoactivated hydride therapy under hypoxia beyond ROS.

As compared to oxidative phototherapy, studies on reactive reductive species-participating photodynamic therapy (PDT) are rare. Porphyrins are typical photosensitizers restricted by the oxygen level, but efficacy and selectivity are always incompatible in PDT. Herein, we report that phlorins are ideal hydride (H) donors and explore a water-soluble triphenylphosphonium-modified zinc-coordinated porphyrin (ZnPor) for photogeneration of zinc-cored phlorin (ZnPhl).

Auto-Deactivation of BODIPY-Derived Type I Photosensitizer Post Photodynamic Therapy under Hypoxia.

The long-lasting activity of photosensitizers during photodynamic therapy (PDT) causes excessive damage and arouses great concerns about biosafety. Herein, we synthesized a pyridinium-decorated diiodo-BODIPY compound (PyBDP) and investigated its photosensitizing activity under hypoxic condition in the presence of NADH that is abundant in the mitochondria of hypoxic tumors. The unique property of PyBDP lies in the redox environment-dependent photo-response.

Radical-Based Enantioconvergent Reductive Couplings of Racemic Allenes and Aldehydes.

Transition metal-catalyzed radical-based enantioconvergent reactions have become a powerful strategy to synthesize enantiopure compounds from racemic starting materials. However, existing methods primarily address precursors with central chirality, neglecting those with axial chirality. Herein, we describe the enantioconvergent reductive coupling of racemic allenes with aldehydes, facilitated by a photoredox, chromium, and cobalt triple catalysis system.

Chromium Catalyzed Asymmetric Reformatsky Reaction.

This study describes an unprecedented chromium-catalyzed asymmetric Reformatsky reaction, enabling the synthesis of chiral β-hydroxy carbonyl compounds from α-chlorinated or α-brominated esters and amides. By employing a chiral chromium/diarylamine bis(oxazoline) catalyst, we achieved relatively broad functional group tolerance. Distinct from known reports, the protocol operates under both classical and photoredox conditions, facilitated by the in situ formation of a nucleophilic chiral chromium intermediate through a radical-polar crossover mechanism.

Elevated gut microbiota metabolite bile acids confer protective effects on clinical prognosis in ischemic stroke patients.

Background: There is evidence of an association between the gut microbiota and progression of stroke. However, the relationship between gut microbial metabolites, specifically bile acids (BAs), and post-ischemic stroke disability and poor functional outcomes remains unexplored.

Methods: Patients with acute ischemic stroke (AIS) or transient ischemic attack (TIA) in the Third China National Stroke Registry were grouped according to total bile acid (TBA) quartile on admission.

Impact of alkaline phosphatase on clinical outcomes in patients with ischemic stroke: a nationwide registry analysis.

Background: Data on the association between serum alkaline phosphatase (ALP) levels and clinical outcomes in patients with ischemic stroke (IS) are inconsistent and limited. Therefore, this study aimed to investigate the correlation between ALP and prognosis in patients with IS.

Methods: Patients with acute ischemic stroke (AIS) or transient ischemic attack (TIA) from the Third China National Stroke Registry were divided into four groups according to the quartiles of serum ALP levels on admission.

Access to All-Carbon Quaternary Centers by Photocatalytic Fluoroalkylation of α-Halo Carbonyl Compounds.

Perfluoroalkyl groups have become significantly important in pharmaceutical and agrochemical applications. In this study, we present a visible light-mediated photoredox neutral strategy for the fluoroalkylation of tertiary alkyl chlorides under transition-metal-free conditions. This method allows for the facile synthesis of fluoroalkylated all-carbon quaternary centers, exhibiting excellent functional group compatibility.

A Radical Approach for Asymmetric α-C-H Addition of -Sulfonyl Benzylamines to Aldehydes.

Efficient synthesis of enantioenriched amines is of great importance due to their significant synthetic and biological applications. Photoredox-mediated asymmetric -amino C(sp)-H functionalization offers an atom-economical and sustainable approach to access chiral amines. However, the development of analogous reactions is in its early stages, generally affording chiral amines with a single stereocenter.

Inactivation mechanism of cold plasma combined with 222 nm ultraviolet for spike protein and its application in disinfecting of SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly transmissible virus that has precipitated a worldwide pandemic of coronavirus disease since 2019. Developing an effective disinfection strategy is crucial to prevent the risk of surface cross-contamination by SARS-CoV-2. This study employed pseudovirus and the receptor-binding domain (RBD) protein of SARS-CoV-2 as models to investigate the spike protein inactivation process and its underlying mechanisms using a novel nonthermal technology.

Cr-Catalyzed Asymmetric Cross Aza-Pinacol Couplings for β-Amino Alcohol Synthesis.

Chiral β-amino alcohols are crucial structural motifs found in pharmaceuticals, natural products, and chiral ligands in asymmetric catalysis. Despite previous advances, the development of catalytic approaches to access β-amino alcohols bearing vicinal stereocenters from readily available chemicals remains a prominent challenge. Herein, we describe the Cr-catalyzed asymmetric cross aza-pinacol coupling of aldehydes and -sulfonyl imines.

Structure of a fungal 1,3-β-glucan synthase.

1,3-β-Glucan serves as the primary component of the fungal cell wall and is produced by 1,3-β-glucan synthase located in the plasma membrane. This synthase is a molecular target for antifungal drugs such as echinocandins and the triterpenoid ibrexafungerp. In this study, we present the cryo-electron microscopy structure of 1,3-β-glucan synthase (Fks1) at 2.

Structure, catalysis, chitin transport, and selective inhibition of chitin synthase.

Chitin is one of the most abundant natural biopolymers and serves as a critical structural component of extracellular matrices, including fungal cell walls and insect exoskeletons. As a linear polymer of β-(1,4)-linked N-acetylglucosamine, chitin is synthesized by chitin synthases, which are recognized as targets for antifungal and anti-insect drugs. In this study, we determine seven different cryo-electron microscopy structures of a Saccharomyces cerevisiae chitin synthase in the absence and presence of glycosyl donor, acceptor, product, or peptidyl nucleoside inhibitors.