Selective Mono-Defluorinative Cross-Coupling of Trifluoromethyl arenes via Multiphoton Photoredox Catalysis.

A new cross-coupling of trifluoromethyl arenes has been realized via multiphoton photoredox catalysis. Trifluoromethyl arenes were demonstrated to undergo selective mono-defluorinative alkylation under mild reaction conditions providing access to a series of valuable α,α-difluorobenzylic compounds. The reaction shows broad substrate scope and general functional group tolerance. In addition to the electron-deficient trifluoromethyl arenes that are easily reduced to the corresponding radical anion, more challenging electron-rich substrates were also successfully applied. Steady-State Stern-Volmer quenching studies indicated that the trifluoromethyl arenes were reduced by the multiphoton excited Ir-based photocatalyst.

Angle-Resolved Optical Imaging of Interlayer Rotations in Twisted Bilayer Graphene.

Twisted bilayer graphene (TBG) is a prototypical layered material whose properties are strongly correlated to interlayer coupling. The two stacked graphene layers with distinct orientations are investigated to generate peculiar optical and electronic phenomena. Thus, the rapid, reliable, and nondestructive twist angle identification technique is of essential importance. Here, we integrated the white light reflection spectra (WLRS), the Raman spectroscopy, and the transmission electron microscope (TEM) to propose a facile RGB optical imaging technique that identified the twist angle of the TBG in a large area intuitively with high efficiency. The RGB technique established a robust correlation between the interlayer rotation angle and the contrast difference in the RGB color channels of a standard optical image. The angle-resolved optical behavior is attributed to the absorption resonance matching with the separation of van Hove singularities in the density of states of the TBG. Our study thus developed a route to identify the rotation angle of stacked bilayer graphene by means of a straightforward optical method, which can be further applied in other stacked van der Waals layered materials.

An efficient targeted gene deletion approach for Cochliobolus heterostrophus using Agrobacterium tumefaciens-mediated transformation.

Cochliobolus heterostrophus is a plant pathogenic fungus of southern corn leaf blight, which has been regarded as a model necrotrophic plant pathogen. Many methods have been developed to knock out targeted genes in C. heterostrophus, of which the most widely-used one is protoplast-mediated transformation. However, there are several problems of this method associated with protoplast preparation, DNA product, time consumption, or high cost. In this study, a highly efficient target gene deletion approach in C. heterostrophus was established and optimized, based on Agrobacterium tumefaciens-mediated transformation (ATMT); the transformation efficiency of this approach was 85-88 transformants per 105 conidia, and the homologous recombination efficiency was approximately 68.3%. Furthermore, six gene knockout mutants of C. heterostrophus were obtained using this ATMT method. The phenotypes of this fungus altered in the mutant strains, and the virulence of the mutants significantly reduced compared to of the wild type strain. Taken together, this ATMT system established in this study can be used as a genetic manipulation tool for C. heterostrophus, to better understand the functions of genes and its relation to virulence.

Mechanisms by which the intestinal microbiota affects gastrointestinal tumours and therapeutic effects.

The intestinal microbiota is considered to be a forgotten organ in human health and disease. It maintains intestinal homeostasis through various complex mechanisms. A significant body of research has demonstrated notable differences in the gut microbiota of patients with gastrointestinal tumours compared to healthy individuals. Furthermore, the dysregulation of gut microbiota, metabolites produced by gut bacteria, and related signal pathways can partially explain the mechanisms underlying the occurrence and development of gastrointestinal tumours. Therefore, this article summarizes the latest research progress on the gut microbiota and gastrointestinal tumours. Firstly, we provide an overview of the composition and function of the intestinal microbiota and discuss the mechanisms by which the intestinal flora directly or indirectly affects the occurrence and development of gastrointestinal tumours by regulating the immune system, producing bacterial toxins, secreting metabolites. Secondly, we present a detailed analysis of the differences of intestinal microbiota and its pathogenic mechanisms in colorectal cancer, gastric cancer, hepatocellular carcinoma, etc. Lastly, in terms of treatment strategies, we discuss the effects of the intestinal microbiota on the efficacy and toxic side effects of chemotherapy and immunotherapy and address the role of probiotics, prebiotics, FMT and antibiotic in the treatment of gastrointestinal tumours. In summary, this article provides a comprehensive review of the pathogenic mechanisms of and treatment strategies pertaining to the intestinal microbiota in patients with gastrointestinal tumours. And provide a more comprehensive and precise scientific basis for the development of microbiota-based treatments for gastrointestinal tumours and the prevention of such tumours.

Highly efficient gene knockout system in the maize pathogen Colletotrichum graminicola using Agrobacterium tumefaciens-mediated transformation (ATMT).

Colletotrichum graminicola, a hemibiotrophic pathogenic fungus, is the causal agent of anthracnose of maize, which causes significant yield losses worldwide, especially in warm and humid maize production regions. An efficient targeted genes knockout protocol is crucial to explore molecular mechanisms of fungal virulence to the host. In this study, we established a gene knockout transformation system by employing Agrobacterium tumefaciens-mediated transformation to knockout genes in M 1.001 strain of C. graminicola. The conidia germination status, induction medium type, and ratio of Agrobacterium cell and conidia suspension were optimized for the knockout of CgBRN1(OR352905), a gene relating to the fungal melanin biosynthesis pathway. Additionally, CgPKS18 (OR352906) and CgCDC25 (OR352903) were knocked out to test the applicability of the gene knockout transformation system. In this established system, transformation efficiency was 176 transformants per 1 × 105 conidia and the homologous recombination efficiency was 53.3 to 75%. Furthermore, disease index, lesion number and lesion size caused by the three above-mentioned mutant strains were found to be reduced significantly compared to the wild-type strain, which indicated reduction in fungal virulence due to the lack of those genes.

Measurement and control of containing-fluorine particulate matter emission during spent pot lining combustion detoxification process.

The particle size distribution (PSD), composition, morphology, and formation mechanism of particulate matter (PM) released from the combustion of spent pot lining with and without CaSiO3 were investigated. The results showed that NaF and Na3AlF6 were found to be the main compositions of PM, and the particle size distribution of PM shows a bimodal distribution. CaSiO3 substantially inhibited the emission of PM by transforming NaF, Na3AlF6, and CaF2 into stable Ca4Si2O7F2. Moreover, CaSiO3 also limited the formation of high hazardous PM0.2 by providing SiO2, Al2O3, and NaAlSiO4 with high melting points as the core of promoting the growth of PM in particle size.

Nickel-Catalyzed C-Heteroatom Cross-Coupling Reactions under Mild Conditions via Facilitated Reductive Elimination.

The formation of C-heteroatom bonds represents an important type of bond-forming reaction in organic synthesis and often provides a fast and efficient access to privileged structures found in pharmaceuticals, agrochemical and materials. In contrast to conventional Pd- or Cu-catalyzed C-heteroatom cross-couplings under high-temperature conditions, recent advances in homo- and heterogeneous Ni-catalyzed C-heteroatom formations under mild conditions are particularly attractive from the standpoint of sustainability and practicability. The generation of NiIII and excited NiII intermediates facilitate the reductive elimination step to achieve mild cross-couplings. This review provides an overview of the state-of-the-art approaches for mild C-heteroatom bond formations and highlights the developments in photoredox and nickel dual catalysis involving SET and energy transfer processes; photoexcited nickel catalysis; electro and nickel dual catalysis; heterogeneous photoredox and nickel dual catalysis involving graphitic carbon nitride (mpg-CN), metal organic frameworks (MOFs) or semiconductor quantum dots (QDs); as well as more conventional zinc and nickel dual catalyzed reactions.

One Amine-3†Tasks: Reductive Coupling of Imines with Olefins in Batch and Flow.

Owing to their wide range of biological properties, γ-aminobutyric acid derivatives (GABA) have been extensively studied and found noteworthy industrial applications. However, atom-economical and efficient processes for their production are scarce and would greatly benefit from further investigations. Herein, we demonstrate that an iridium-based photocatalyst promotes the direct reductive cross-coupling of imines with olefins upon irradiation with visible light to give GABA derivatives in good yields and selectivities. We also stress the enabling triple role of tributylamine additive in this process, discuss the advantages of strategies based on proton-coupled electron transfer (PCET) and demonstrate the scale-up of this reaction in continuous flow.

Allylic C(sp3)-H alkylation via synergistic organo- and photoredox catalyzed radical addition to imines.

A new catalytic method for the direct alkylation of allylic C(sp3)-H bonds from unactivated alkenes via synergistic organo- and photoredox catalysis is described. The transformation achieves an efficient, redox-neutral synthesis of homoallylamines with broad functional group tolerance, under very mild reaction conditions. Mechanistic investigations indicate that the reaction proceeds through the N-centered radical intermediate which is generated by the allylic radical addition to the imine.

Brønsted Base Assisted Photoredox Catalysis: Proton Coupled Electron Transfer for Remote C-C Bond Formation via Amidyl Radicals.

The synthesis of alkyne- and alkene-decorated lactams has been achieved through a photoredox-initiated radical cascade reaction. The developed Brønsted base assisted, photoredox-catalyzed, intramolecular 5-exo-trig cyclization/intermolecular radical addition/elimination reaction provides facile access to functionalized γ-lactams, with good functional group tolerance and high yields.

Synthesis of Amidines from Amides Using a Nickel-Catalyzed Decarbonylative Amination through CO Extrusion Intramolecular Recombination Fragment Coupling.

A catalytic synthesis of amidines from amides has been established for the first time. The newly developed CO extrusion recombination process takes advantage of an inexpensive nickel(II) catalyst and provides the corresponding amidines with high efficiency. The intramolecular fragment coupling shows excellent chemoselectivity, starts from readily available amides, and provides a valuable alternative amidine synthesis protocol.

Decarboxylative Aminomethylation of Aryl- and Vinylsulfonates through Combined Nickel- and Photoredox-Catalyzed Cross-Coupling.

A mild approach for the decarboxylative aminomethylation of aryl sulfonates by the combination of photoredox and nickel catalysis through C-O bond cleavage is described for the first time. A wide range of aryl triflates as well as aryl mesylates, tosylates and alkenyl triflates afford the corresponding products in good to excellent yields.

An organocatalytic Mannich/denitration reaction for the asymmetric synthesis of 3-ethylacetate-substitued 3-amino-2-oxindoles: formal synthesis of AG-041R.

The highly enantioselective organocatalytic addition of ethyl nitroacetate to isatin-derived N-Boc ketimines (Boc = tert-butoxycarbonyl), followed by the removal of the nitro group, is described. The scalable reaction sequence leads to the title compounds as important intermediates of pyrroloindoline alkaloids and related drugs in excellent yields and enantioselectivities. The synthesis of the hexahydrofurano[2,3-b]indole skeleton, the spirocarbamate oxindole unit, and the formal synthesis of AG-041R have been carried out to demonstrate the synthetic utility of this protocol.