PTPN9 dephosphorylates FGFR2 pY656/657 through interaction with ACAP1 and ameliorates pemigatinib effect in cholangiocarcinoma.

ABSTRACT AND AIM: Cholangiocarcinoma (CCA) is a highly aggressive and lethal cancer that originates from the biliary epithelium. Systemic treatment options for CCA are currently limited, and the first targeted drug of CCA, pemigatinib, emerged in 2020 for CCA treatment by inhibiting FGFR2 phosphorylation. However, the regulatory mechanism of FGFR2 phosphorylation is not fully elucidated. APPROACH AND RESULTS: Here we screened the FGFR2-interacting proteins and showed that protein tyrosine phosphatase (PTP) N9 interacts with FGFR2 and negatively regulates FGFR2 pY656/657 . Using phosphatase activity assays and modeling the FGFR2-PTPN9 complex structure, we identified FGFR2 pY656/657 as a substrate of PTPN9, and found that sec. 14p domain of PTPN9 interacts with FGFR2 through ACAP1 mediation. Coexpression of PTPN9 and ACAP1 indicates a favorable prognosis for CCA. In addition, we identified key amino acids and motifs involved in the sec. 14p-APCP1-FGFR2 interaction, including the "YRETRRKE" motif of sec. 14p, Y471 of PTPN9, as well as the PH and Arf-GAP domain of ACAP1. Moreover, we discovered that the FGFR2 I654V substitution can decrease PTPN9-FGFR2 interaction and thereby reduce the effectiveness of pemigatinib treatment. Using a series of in vitro and in vivo experiments including patient-derived xenografts (PDX), we showed that PTPN9 synergistically enhances pemigatinib effectiveness and suppresses CCA proliferation, migration, and invasion by inhibiting FGFR2 pY656/657 . CONCLUSIONS: Our study identifies PTPN9 as a negative regulator of FGFR2 phosphorylation and a synergistic factor for pemigatinib treatment. The molecular mechanism, oncogenic function, and clinical significance of the PTPN9-ACAP1-FGFR2 complex are revealed, providing more evidence for CCA precision treatment.

Metal-Free Cyanation of gem-Difluoroalkenes via Azide-Mediated C-C Double Bond Fragmentation.

Activation and cleavage of C-C double bonds are long-standing challenges in synthetic chemistry. Herein, we report an unprecedented azide-mediated C-C double bond fragmentation of gem-difluoroalkenes under mild and metal-free conditions, enabling the efficient synthesis of structurally diverse aromatic nitriles in moderate to good yields. This protocol is also amenable to the cyanation of gem-dichloro and dibromo alkenes. This reaction features simple operation and good functional group compatibility and can be implemented at a gram scale.

Ag-Catalyzed Practical Synthesis of N-Acyl Anthranilic Acids from Anthranils and Carboxylic Acids.

A practical synthesis of valuable N-acyl anthranilic acids has been achieved via a silver-catalyzed imino-ketene generation from readily available anthranils and carboxylic acids. A wide range of carboxylic acids including sterically demanding aliphatic carboxylic acids, aromatic carboxylic acids, acrylic acids, and amino acids are compatible in this reaction. Moreover, this method can be used to modify drug molecules and natural products, such as ibuprofen, probenecid, and acetylglycine.

Low-oxygen rare earth steels.

Rare earth (RE) addition to steels to produce RE steels has been widely applied when aiming to improve steel properties. However, RE steels have exhibited extremely variable mechanical performances, which has become a bottleneck in the past few decades for their production, utilization and related study. Here in this work, we discovered that the property variation of RE steels stems from the presence of oxygen-based inclusions. We proposed a dual low-oxygen technology, and keeping low levels of oxygen content in steel melts and particularly in the raw RE materials, which have long been ignored, to achieve impressively stable and favourable RE effects. The fatigue life is greatly improved by only parts-per-million-level RE addition, with a 40-fold improvement for the tension-compression fatigue life and a 40% enhancement of the rolling contact fatigue life. We find that RE appears to act by lowering the carbon diffusion rate and by retarding ferrite nucleation at the austenite grain boundaries. Our study reveals that only under very low-oxygen conditions can RE perform a vital role in purifying, modifying and micro-alloying steels, to improve the performance of RE steels.

Tf2O-Promoted Chemoselective C3 Functionalization of Anthranils with Phenols and Thiophenols.

Different chemoselectivities of phenols and thiophenols were observed in a Tf2O-promoted C3 functionalization of simple anthranils. The reaction of phenols and anthranils gives 3-aryl anthranils via a C-C bond formation, whereas thiophenols afford 3-thio anthranils through a C-S bond formation. Both reactions have a broad substrate scope and tolerate a wide range of functional groups, affording the corresponding products with specific chemoselectivity.

Practical synthesis of isocoumarins via Rh(III)-catalyzed C-H activation/annulation cascade.

Herein, we report an unprecedented Rh(III)-catalyzed C-H activation/annulation cascade of readily available enaminones with iodonium ylides towards the convenient synthesis of isocoumarins. This coupling system proceeds in useful chemical yields (up to 93%) via a cascade C-H activation, Rh-carbenoid migratory insertion and acid-promoted intramolecular annulation. The success of gram-scale reaction and diverse functionalization of isocoumarins demonstrated the synthetic utility of this protocol.

NiH-Catalyzed Proximal-Selective Hydroamination of Unactivated Alkenes with Anthranils.

The regioselective hydroamination of unactivated alkenes is a long-standing challenge in organic synthesis. Herein, we report a NiH-catalyzed proximal-selective hydroamination of unactivated alkenes with 8-aminoquinoline (AQ) as a bidentate auxiliary and anthranils as aminating reagents. A wide range of primary aryl amines bearing an ortho-carbonyl group were installed in both terminal and internal unactivated alkenes, delivering a variety of valuable ß- and γ-amino acid building blocks, respectively, with excellent regiocontrol. The utility of this transformation was further demonstrated by the conversion of the multifunctionalized aryl amines into useful N-heterocycles.

[Meta-analysis of Shenqi Jiangtang Granules combined with western medicine on adverse pregnancy outcomes in women with gestational diabetes mellitus].

The present study evaluated the effect of Shenqi Jiangtang Granules(SJG) combined with western medicine on the adverse pregnancy outcomes in women with gestational diabetes mellitus(GDM). PubMed, Web of Science, CNKI, Wanfang, and VIP were searched for clinical randomized controlled trials(RCTs) of SJG combined with western medicine against GDM. The included RCTs were assessed for risks using the assessment criteria recommended by the Cochrane handbook for systematic reviews of interventions. Meta-analysis was performed using Stata 12.0 and RevMan 5.3. Nineteen RCTs were included, with 1 647 patients involved, including 824 cases treated with western medicine alone, and 823 cases treated with SJG combined with western medicine. The course of treatment ranged from 2 to 12 weeks. As revealed by Meta-analysis results, compared with western medicine treatment alone, SJG combined with western medicine could reduce the incidence of postpartum hemorrhage(OR=0.23, 95%CI[0.10, 0.53], P=0.000 6), gestational hypertension(OR=0.24, 95%CI[0.13, 0.45], P<0.000 01), polyhydramnios(OR=0.24, 95%CI[0.12, 0.45], P<0.000 1), premature rupture of membranes(OR=0.20, 95%CI[0.09, 0.45], P<0.000 1), cesarean section(OR=0.40, 95%CI[0.29, 0.55], P<0.000 01), macrosomia(OR=0.19, 95%CI[0.08, 0.47], P<0.000 3), neonatal asphyxia(OR=0.22, 95%CI[0.12, 0.40], P<0.000 01), premature delivery(OR=0.19, 95%CI[0.12, 0.30], P<0.000 01), proteinuria(OR=0.19, 95%CI[0.06, 0.58], P=0.004) and hypoglycemia(OR=0.28, 95%CI[0.16, 0.50], P<0.000 1). The funnel plots and Egger's test showed that except macrosomia, there was no significant publication bias in the results of other indicators. Therefore, as indicated by the findings, SJG combined with western medicine can reduce the incidence of adverse pregnancy outcomes in GDM patients. However, due to the uneven quality of the included trials, the clinical application of this protocol requires caution.

Suppression of Chain Transfer at High Temperature in Catalytic Olefin Polymerization.

Living polymerization by suppressing chain transfer is a very useful method for achieving precise molecular weight and structure control. However, the suppression of chain transfer at high temperatures is extremely challenging in any catalytic polymerization. This has been a severe limitation for catalytic olefin polymerization, which is one of the most important chemical reactions. Here, we report the unprecedented living polymerization of ethylene at 130 °C, with a narrow molecular weight distribution range of 1.04 to 1.08. This is a significant increase in the reaction temperature. Tailor-made α-diimine nickel catalysts that exhibit both the steric shielding and fluorine effects play an essential role in this breakthrough. These nickel catalysts are even active at 200 °C, and enable the formation of semi-crystalline, ultrahigh-molecular-weight polyethylene at 150 °C. Mechanistic insights into the key chain transfer reaction are elucidated by density functional theory calculations.

Fluorinated α-Diimine Nickel Mediated Ethylene (Co)Polymerization.

Fluorine substituents in transition metal catalysts are of great importance in olefin polymerization catalysis; however, the comprehensive effect of fluorine substituents is elusive in seminal late transition metal α-diimine catalytic system. In this contribution, fluorine substituents at various positions (ortho-, meta-, and para-F) and with different numbers (Fn ; n=0, 1, 2, 3, 5) were installed into the well-defined N-terphenyl amine and thus were studied for the first time in the nickel α-diimine promoted ethylene polymerization and copolymerization with polar monomers. The position of the fluorine substituent was particularly crucial in these polymerization reactions in terms of catalytic activity, polymer molecular weight, branching density, and incorporation of polar monomer, and thus a picture on the fluorine effect was given. As a notable result, the ortho-F substituted α-diimine nickel catalyst produced highly linear polyethylenes with an extremely high molecular weight (Mw =8703 kDa) and a significantly low degree of branching of 1.4/1000 C; however, the meta-F and/or para-F substituted α-diimine nickel catalysts generated highly branched (up to 80.2/1000 C) polyethylenes with significantly low molecular weights (Mw =20-50 kDa).

Nickel-Catalyzed Hydroamination of Olefins with Anthranils.

A nickel-catalyzed polarity-reversed hydroamination of olefins has been achieved with anthranils as the electrophilic aminating agents and hydrosilane as the reductant. This protocol provides a facile access to N-alkyl-2-aminobenzophenones that are versatile intermediates in organic synthesis. A wide range of olefins and anthranils are compatible in this transformation, delivering the desired amines in useful to excellent yields (38 examples, up to 92% yield). The utility of this protocol is exhibited in the late-stage functionalization of drug molecules and the valuable derivatives of the obtained amination products.

Copper-Catalyzed Electrophilic Amination of Arylboronic Acids with Anthranils: An Access to N-Aryl-2-aminophenones.

An efficient copper-catalyzed electrophilic amination strategy has been established for the rapid synthesis of N-aryl-2-aminophenones from readily available arylboronic acids/esters and anthranils. This protocol features good functional group tolerance, broad substrate scope, and operational simplicity. Moreover, a tandem C-H borylation and C-N coupling protocol has also been developed to transform simple arenes to the valuable N-aryl-2-aminophenones in one pot. Additionally, the synthetic potential of this methodology is further demonstrated by the synthesis of various useful N-heterocycles and derivatives.

Recent Advances in Catalytic Synthesis of Benzosultams.

Benzosultams represent one category of multi-heteroatom heterocyclic scaffolds, which have been frequently found in pharmaceuticals, agricultural agents, and chiral catalysts. Given the diversely significant functions of these compounds in organic and medicinal chemistry, great efforts have been made to develop novel catalytic systems for the efficient construction of benzosultam motifs over the past decades. Herein, in this review, we mainly summarize the recent advances in the field of catalytic synthesis of benzosultams from 2017 to August of 2020, with an emphasis on the scopes and mechanisms of representative reactions.

Exploration of Visible-Light Photocatalysis in Heterocycle Synthesis and Functionalization: Reaction Design and Beyond.

Visible-light photocatalysis has recently received increasing attention from chemists because of its wide application in organic synthesis and its significance for sustainable chemistry. This catalytic strategy enables the generation of various reactive species, frequently without stoichiometric activation reagents under mild reaction conditions. Manipulation of these reactive intermediates can result in numerous synthetically useful bond formations in a controllable manner. In this Account, we describe our recent advances in the rational design and strategic application of photocatalysis in the synthesis of various synthetically and biologically important heterocycles. Our main research efforts toward this goal can be classified into four categories: formal cycloaddition and cyclization reactions, radical-mediated olefin functionalization/cyclization cascades, photocatalytic generation and cyclization of N-centered radicals, and photocatalytic functionalization of heterocycles by visible-light-induced dual catalysis. Inspired by the wide application of tertiary amines as reductive additives in photoredox catalysis, we exploited a series of readily accessible or rationally designed tertiary amines with reactive sites in a range of photocatalytic formal cycloaddition and cyclization reactions, providing efficient access to diverse nitrogen heterocycles. Employing various photogenerated radical species, we further developed a series of radical-mediated olefin functionalization/cyclization cascade reactions to successfully assemble various five- and six-membered heterocycles. We have also achieved for the first time the direct catalytic conversion of recalcitrant N-H bonds into neutral N-centered radicals through a visible-light-photocatalytic oxidative deprotonation electron transfer. Using this generic strategy, we have devised several types of radical cyclizations of unsaturated hydrazones, leading to the construction of diversely functionalized pyrazoline and pyridazine derivatives in good yields and selectivity. Moreover, we have demonstrated that this photocatalysis can serve as a mild and highly selective tool for direct functionalization of heterocycles because of its powerful capability to controllably generate diverse reactive intermediates under mild reaction conditions. Guided by the fundamental principles of photocatalysis and the redox properties of the photocatalysts, we successfully developed an array of dual-catalyst systems by combining the photocatalysts with palladium, nickel, or amine, enabling efficient and selective coupling reactions. An intriguing phototandem catalytic system using a single photocatalyst was also identified for the development of cascade reactions. Notably, some of the newly developed methodologies have also been successfully utilized for late-stage modification of biologically active natural compounds and complex molecules and as key steps for formal synthesis of natural products. This Account presents a panoramic view and the logic of our recent contributions to the design, development, and application of photocatalytic systems and reactions that provide not only methods for the efficient synthesis of heterocycles but also useful insights into the exploration of new photochemical reactions.

Visible light photoredox-controlled reactions of N-radicals and radical ions.

Radicals are an important class of versatile and highly reactive species. Compared with the wide applications of various C-centred radicals, however, the N-radical species including N-centred radicals and radical ions remain largely unexplored due to the lack of convenient methods for their generation. In recent years, visible light photoredox catalysis has emerged as a powerful platform for the generation of various N-radical species and methodology development towards the synthesis of diverse N-containing compounds. In this tutorial review, we highlight recent advances in this rapidly developing area with particular emphases put on the working models and new reaction design.

Controllable Remote C-H Bond Functionalization by Visible-Light Photocatalysis.

Remote control: New strategies for the activation of remote C(sp3 )-H bonds by photoredox-catalyzed (PC) radical translocation via O- and N-centered radicals have recently been described. These methods enable the controlled and site-selective functionalization of inert C(sp3 )-H bonds and provide new opportunities for reaction design (HAT=hydrogen atom transfer).

Organophotocatalytic Generation of N- and O-Centred Radicals Enables Aerobic Oxyamination and Dioxygenation of Alkenes.

A cooperative TEMPO and photoredox catalytic strategy was applied for the first time to the direct conversion of N-H and O-H bonds into N- and O-centred radicals, enabling a general and selective oxidative radical oxyamination and dioxygenation of various ß,γ-unsaturated hydrazones and oximes. In the reaction, O2 was employed not only as a terminal oxidant but also as the oxygen source. This protocol provided efficient access to the synthesis of various synthetically and biologically important pyrazoline, pyridazine and isoxazoline derivatives under metal-free and mild reaction conditions. Mechanistic studies revealed that the cooperative organophotocatalytic system functions through two single-electron-transfer (SET) processes.

Effect and mechanism of pyridoxamine on the lipid peroxidation and stability of polyunsaturated fatty acids in beef patties.

BACKGROUND: Little is known about how vitamins can affect the peroxidation and stability of polyunsaturated fatty acids in cooked foods. Thus the effects of 15 vitamins on toxic malondialdehyde (MDA) formation in cooked beef patties were examined with the application of solid phase extraction and thiobarbituric acid (TBA) analysis by HPLC-DAD. The polyunsaturated fatty acid profiles in cooked beef patties treated with some vitamins were further compared with that of control sample (no vitamin addition) by GC-MS analysis. RESULTS: Pyridoxamine, pyridoxine, retinoic acid, α-tocopherol and L-ascorbic acid exhibited significant effects lowering the amount of MDA. It was further discovered that retinoic acid, α-tocopherol and l-ascorbic acid could help preserve polyunsaturated fatty acids, while pyridoxamine addition actually showed no effect upon the retention of most of the tested polyunsaturated fatty acids, even lowering the content of arachidonic acid. Further LC-MS analysis demonstrated that pyridoxamine could directly react with MDA via an addition reaction. The reaction involves a nucleophilic attack of pyridoxamine's free amine group on one of the aldehyde functional groups of MDA to form a new adduct, and may accelerate lipid peroxidation with the loss of more polyunsaturated fatty acids. CONCLUSION: Some vitamins may directly participate in lipid peroxidation and affect food quality. © 2015 Society of Chemical Industry.

PhI(OAc)2-mediated functionalisation of unactivated alkenes for the synthesis of pyrazoline and isoxazoline derivatives.

A PhI(OAc)2-promoted radical cyclization of ß,γ-unsaturated hydrazones and oximes has been developed for an efficient synthesis of various valuable pyrazoline and isoxazoline derivatives with satisfactory yields (up to 96%) under mild conditions.