Domino dehydration/intermolecular (enantioselective) ketone-ene reactions catalysed by a simple solid in batch and in flow.

The intermolecular carbonyl-ene reaction of ketones is still considered a challenge in organic chemistry, particularly with reusable solid catalysts, and implemented in a domino reaction. Herein, we show that the extremely cheap and non-toxic solid salt MgCl catalyzes the reaction of trifluoromethyl pyruvates not only during the conventional carbonyl-ene reaction with various aromatic and alkyl alkenes (in very high yields, up to >99%) but also in a domino reaction with the corresponding alcohols (precursors to the alkenes) in similar good yields. The solid can be reused in both cases without any erosion of the catalytic activity and can be employed in an in-flow process to maximize the reaction throughput.

Soluble individual metal atoms and ultrasmall clusters catalyze key synthetic steps of a natural product synthesis.

Metal individual atoms and few-atom clusters show extraordinary catalytic properties for a variety of organic reactions, however, their implementation in total synthesis of complex organic molecules is still to be determined. Here we show a 11-step linear synthesis of the natural product (±)-Licarin B, where individual Pd atoms (Pd) catalyze the direct aerobic oxidation of an alcohol to the carboxylic acid (steps 1 and 6), Cu clusters catalyze carbon-oxygen cross couplings (steps 3 and 8), Pd clusters catalyze a Sonogashira coupling (step 4) and Pt clusters catalyze a Markovnikov hydrosylilation of alkynes (step 5), as key reactions during the synthetic route. In addition, the new synthesis of Licarin B showcases an unexpected selective alkene hydrogenation with metal-free NaBH and an acid-catalyzed intermolecular carbonyl-olefin metathesis as the last step, to forge a trans-alkene group.

Advancements in Home-Based Devices for Detecting Obstructive Sleep Apnea: A Comprehensive Study.

Obstructive Sleep Apnea (OSA) is a respiratory disorder characterized by frequent breathing pauses during sleep. The apnea-hypopnea index is a measure used to assess the severity of sleep apnea and the hourly rate of respiratory events. Despite numerous commercial devices available for apnea diagnosis and early detection, accessibility remains challenging for the general population, leading to lengthy wait times in sleep clinics.

Direct C-H Arylation of Dithiophene-Tetrathiafulvalene: Tuneable Electronic Properties and 2D Self-Assembled Molecular Networks at the Solid/Liquid Interface.

Invited for the cover of this issue is the group of Manuel Souto and co-workers at the University of Aveiro and CICECO-Aveiro Institute of Materials. The image depicts the direct C-H arylation of dithiophene-tetrathiafulvalene (DT-TTF) and the self-assembly of DT-TTF-tetrabenzoic acid studied by using scanning tunnelling microscopy. Read the full text of the article at 10.

Direct C-H Arylation of Dithiophene-Tetrathiafulvalene: Tuneable Electronic Properties and 2D Self-Assembled Molecular Networks at the Solid/Liquid Interface.

Tetrathiafulvalene is among the best known building blocks in molecular electronics due to its outstanding electron-donating and redox properties. Among its derivatives, dithiophene-tetrathiafulvalene (DT-TTF) has attracted considerable interest in organic electronics, owing to its high field-effect mobility. Herein, we report the direct C-H arylation of DT-TTF to synthesise mono- and tetraarylated derivatives functionalised with electron-withdrawing and electron-donating groups in order to evaluate their influence on the electronic properties by cyclic voltammetry, UV-vis spectroscopy and theoretical calculations.

Using zebrafish embryo bioassays combined with high-resolution mass spectrometry screening to assess ecotoxicological water bodies quality status: A case study in Panama rivers.

Several studies show that many water bodies in developing countries are increasingly affected by anthropogenic pressure, such as agricultural activities, domestic and industrial wastewater. However, data is scarce in several of such countries, including Panama. Thus, in this work, the ecotoxicological status of selected rivers in Panama with distinct input sources were evaluated using the zebrafish (Danio rerio) embryo bioassays combined with a liquid chromatography-high resolution mass spectrometry screening of contaminants of emerging concern (CECs), using a library of over 3200 chemicals.

Response of the ArcCHECK® device at 6 MV and 15 MV for VMAT and IMRT quality control.

Purpose: To study the response of the ArcCHECK® device as VMAT and IMRT verification system.

Methods: Various tests analyzing the linearity, the repeatability and the angular dependence of the device response, its dependence with the pulse repetition rate and the leakage losses were performed. The long-term response in dose measurements and the uniformity of the detectors conforming the system were controlled using a statistical process control program.

Synthesis of Unprotected Spirocyclic β-Prolines and β-Homoprolines by Rh-Catalyzed C-H Insertion.

A series of unprotected spirocyclic β-prolines and β-homoprolines are prepared by Rh-catalyzed C-H insertion. The key intermediate, a Rh nitrenoid, is generated by the N-O bond cleavage of a substituted isoxazolidin-5-one. The reaction proceeds on a gram scale with a catalyst loading of as little as 0.

Traceless Electrophilic Amination for the Synthesis of Unprotected Cyclic β-Amino Acids.

Electrophilic aminations involve an umpolung of a nitrogen atom, providing an alternate, distinctive synthetic strategy. The recent advent of various designed O-substituted hydroxylamines has significantly advanced this research field. An underappreciated issue is atom economy of the transformations: The necessary activating group on the oxygen atom is left in coproduced waste.

Catalytic Asymmetric Formal [3+2] Cycloaddition of 2-Isocyanatomalonate Esters and Unsaturated Imines: Synthesis of Highly Substituted Chiral γ-Lactams.

Unlike their isocyano and isothiocyanato analogues, isocyanato esters remain almost unexplored as formal 1,3-dipoles in asymmetric catalytic reactions. The first asymmetric formal [3+2] cycloaddition involving isocyanato esters and electrophilic alkenes is reported. Diisopropyl 2-isocyanatomalonate reacts with α,β-unsaturated N-(o-anisidyl) imines in the presence of a Mg(OTf) -BOX complex to give highly substituted chiral pyrrolidinones featuring a conjugate exocyclic double bond with excellent yields and enantiomeric excesses up to 99 %.

Copper-catalysed enantioselective Michael addition of malonic esters to β-trifluoromethyl-α,β-unsaturated imines.

Copper triflate-BOX complexes catalyse the enantioselective conjugate addition of methyl malonate to β-trifluoromethyl-α,β-unsaturated imines to give the corresponding enamines bearing a trifluoromethylated stereogenic centre with good yields, and diastereo- and enantioselectivities. The usefulness of the method has been shown with the synthesis of optically active β-trifluoromethyl δ-amino esters and optically active trifluoromethyl piperidones.

Variation of saponin contents and physiological status in Quillaja saponaria under different environmental conditions.

Quillaja saponaria (Quillay), an evergreen tree found in Chile, is one of the main sources of saponins. Quillaja saponins have hypocholesterolaemic, anticarcinogenic, antioxidant and pesticidal properties, and are used as adjuvants for vaccines. Samples of Quillay growing at three zones in O'Higgins Region, Chile (Coastal, Central and Mountain zones) were analyzed for content of saponins and physiological status.

Imported strongyloidiasis in Spain.

Objectives: The objective of this study was to assess the epidemiological, laboratory, and clinical features of imported strongyloidiasis in a tropical medicine referral unit in Madrid, Spain.

Methods: This was a retrospective study based on a review of medical records. A patient was diagnosed with strongyloidiasis when the infection could be detected by conventional stool analysis and/or serology against Strongyloides stercoralis, regardless of the presence of symptoms.

Asymmetric conjugate addition of malonate esters to α,β-unsaturated N-sulfonyl imines: an expeditious route to chiral δ-aminoesters and piperidones.

The asymmetric conjugate addition of malonate esters to α,β-unsaturated N-sulfonyl imines is catalyzed by PyBOX/La(OTf)3 complexes in the presence of 4 Å MS. The reaction gives the corresponding E enamines bearing a stereogenic center at the allylic position with good yields and enantiomeric ratios up to 97:3. This reaction provides a synthetic entry to chiral δ-aminoesters and piperidones.