Triple Catalysis for the Tandem Transformation of Cyclopropyl Ketones to SCF3-Substituted Dihydrofurans.

In this study, we have developed an effective and general strategy for synthesizing various 4-[(trifluoromethyl)thio]-2,3-dihydrofuran derivatives with high regioselectivity from easily prepared cyclopropyl ketone under mild reaction conditions. By the combination of photoredox, copper, and Lewis acid catalysis into a triple catalytic system, this methodology facilitates the selective cleavage of the carbon-carbon bonds and the formation of new carbon-oxygen and carbon-sulfur bonds. In addition, to enhance the synthetic feasibility of this protocol, we demonstrate its broad applicability across a wide range of substrates and its scalability for large-scale synthesis.

Photocatalyzed Direct C(sp3)-H Alkenylation of Unactivated Alkanes via Tandem C-C Activation of Cyclopropenes.

A highly adaptable method has been developed for the alkenylation of a broad spectrum of inert alkanes, employing milder reaction conditions. Tetrabutylammonium decatungstate (TBADT) serves as a photocatalyst for hydrogen atom transfer (HAT), instigating the formation of transient alkyl radicals through C(sp3)-H functionalization. These radicals exhibit regioselective addition to cyclopropenes, followed by the subsequent activation of C-C bonds, forming the corresponding vinylated derivatives. This methodology accommodates diverse unreactive C(sp3)-H bond motifs and multisubstituted cyclopropenes, enabling the efficient synthesis of highly functionalized olefins with high diastereoselectivity.

Scavengers in the human-dominated landscape: an experimental study.

Rapid urbanization is a major cause of habitat and biodiversity loss and human-animal conflict. While urbanization is inevitable, we need to develop a good understanding of the urban ecosystem and the urban-adapted species, in order to ensure sustainable cities for our future. Scavengers play a major role in urban ecosystems, and often, urban adaptation involves a shift towards scavenging behaviour in wild animals. We experimented at different sites in the state of West Bengal, India, to identify the scavenging guild within urban habitats, in response to human-provided food. Our study found a total of 17 different vertebrate species across 15 sites, over 498 sessions of observations. We carried out network analysis to understand the dynamics of the system and found that the free-ranging dog and common myna were key species within the scavenging networks. This study revealed the complexity of scavenging networks within human-dominated habitats. This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'.

Organophotoredox Catalysis: Switchable Radical Generation from Alkyl Sodium Sulfinates for Sulfonylation and Alkylative Activation of C-C Bonds of Cyclopropenes.

Generating alkyl radicals from the sulfonyl radicals remains challenging in synthetic chemistry. Here, we report an efficient photocatalyzed strategy using alkyl sodium sulfinates as both sulfonylating and alkylating reagents by controlling the reaction temperature. This methodology provides a versatile protocol for synthesizing diastereoselective sulfonylated cyclopropanes and poly-substituted styrene derivatives. This methodology is successfully demonstrated with a wide variety of cyclopropenes and alkyl sulfinates, showcasing its broad substrate scope, high diastereo- and E/Z selectivity, and yielding good to excellent yields.

Visible light-induced organo-photocatalyzed route to synthesize substituted pyrazoles.

The synthesis of tetra-substituted pyrazoles holds significant synthetic value and has been accomplished through an organo-photocatalyzed decarboxylative intramolecular cyclization using readily available 1,2-diaza-1,3-dienes and α-ketoacids. This method allows for the systematic synthesis of substituted pyrazole derivatives. Notably, this approach is characterized by its metal-free and oxidant-free nature, offering distinct advantages such as short reaction times and exceptionally mild reaction conditions. The developed methodology enables the efficient construction of tetra-substituted pyrazoles, expanding the available chemical space for exploration and opening up potential applications in various scientific fields.

Diastereoselective Hydroacylation of Cyclopropenes by Visible-Light Photocatalysis.

An efficient and general strategy for the hydroacylation of cyclopropene is disclosed for synthesizing various 2-acylcyclopropane derivatives under mild reaction conditions. High functional group tolerance of this protocol features a novel route to access a divergent synthesis of acylated cyclopropane in a diastereoselective manner by photoinduced decarboxylation of α-ketoacid followed by acyl radical addition to cyclopropene. Additionally, the regioselective addition of acyl radical at the least substituted olefinic carbon center with trans-selective fashion makes this protocol more appealing toward natural product development.

TEMPO-Mediated Selective Synthesis of Isoxazolines, 5-Hydroxy-2-isoxazolines, and Isoxazoles via Aliphatic δ-C(sp3)-H Bond Oxidation of Oximes.

Selective synthesis of three different bioactive heterocycles; isoxazolines, 5-hydroxy-2-isoxazolines and isoxazoles from the same starting material using TEMPO (2,2,6,6-Tetramethylpiperidin-1-oxyl) as a radical initiator is reported. Selectivity was achieved using different oxidants with TEMPO. The reaction goes through a 1,5-HAT (hydrogen atom transfer) process resulting in products with good yields. This strategy offers a straightforward route to three different heterocycles from oximes via radical-mediated C(sp3 )-H oxidation.

The Regulatory Effect of VEGF-Ax on Rat Bone Marrow Mesenchymal Stem Cells' Angioblastic Differentiation and Its Proangiogenic Ability.

Vascular endothelial growth factor A (VEGFA), which plays a key role in angiogenesis, is composed of many isoforms. Distinct VEGFA isoforms are generated by alternative splicing of VEGFA mRNA and named as VEGFxxx, where xxx represents the number of amino acids present in the final protein sequence. These isoforms have opponent pro- and antiangiogenic effects. VEGF-Ax, an additional isoform containing a 22-amino-acid extension in the COOH terminus, arising from VEGFA mRNA, programmed translational readthrough. The function of VEGF-Ax is not clear, especially the conclusion that VEGF-Ax regulates angiogenesis is contradictory. Thus, we investigated the effect of VEGF-Ax on differentiation and angiogenesis of rat bone marrow mesenchymal stem cells (BMMSCs). The results showed that VEGF-Ax could promote the proliferation and migration of BMMSCs, stimulate the differentiation of BMMSCs into endothelial cell-like cells, and protect BMMSCs from endoplasmic reticulum stress-induced apoptosis.

Quantification of Thermal Oxidation in Metallic Glass Powder using Ultra-small Angle X-ray Scattering.

In this paper, the composition, structure, morphology and kinetics of evolution during isothermal oxidation of Fe48Cr15Mo14Y2C15B6 metallic glass powder in the supercooled region are investigated by an integrated ex-situ and in-situ characterization and modelling approach. Raman and X-ray diffraction spectra established that oxidation yielded a hierarchical structure across decreasing length scales. At larger scale, Fe2O3 grows as a uniform shell over the powder core. This shell, at smaller scale, consists of multiple grains. Ultra-small angle X-ray scattering intensity acquired during isothermal oxidation of the powder over a wide Q-range delineated direct quantification of oxidation behavior. The hierarchical structure was employed to construct a scattering model that was fitted to the measured intensity distributions to estimate the thickness of the oxide shell. The relative gain in mass during oxidation, computed theoretically from this model, relatively underestimated that measured in practice by a thermogravimetric analyzer due to the distribution in sizes of the particles. Overall, this paper presents the first direct quantification of oxidation in metallic glass powder by ultra-small angle X-ray scattering. It establishes novel experimental environments that can potentially unfold new paradigms of research into a wide spectrum of interfacial reactions in powder materials at elevated temperatures.