Catalytic enantioselective synthesis of fluoromethylated stereocenters by asymmetric hydrogenation.

Fluoromethyl groups possess specific steric and electronic properties and serve as a bioisostere of alcohol, thiol, nitro, and other functional groups, which are important in an assortment of molecular recognition processes. Herein we report a catalytic method for the asymmetric synthesis of a variety of enantioenriched products bearing fluoromethylated stereocenters with excellent yields and enantioselectivities. Various N,P-ligands were designed and applied in the hydrogenation of fluoromethylated olefins and vinyl fluorides.

Analysis of the correlation between the severity of neonatal hypoxic ischemic encephalopathy and multiple organ dysfunction.

OBJECTIVE: To evaluate the hypoxic ischemic encephalopathy (HIE) and multiple organ dysfunction (MOD) in neonates and analyze the correlation between the two disorders. METHODS: From January 2018 to January 2020, infants with HIE who were born in our hospital at or above 37 weeks of gestation, and those with ischemic hypoxic encephalopathy at or above 2000 grams were selected as study subjects. HIE and MOD monitoring were performed for three days. HIE severity was graded according to reported scores including amplitude integrated EEG. Multiple organ dysfunction was also assessed. The correlation between neonatal hypoxic ischemic encephalopathy and multiple organ dysfunction was analyzed. RESULTS: Children with HIE were divided into three grades: mild, moderate and severe. There were statistically significant differences among the three groups in emergency caesarean section, Apgar 5 minutes, systemic hypothermia and neonatal mortality. Differences in MOD scores were found in three HIE stages per day from Day 1 to Day 3. Among children with mild HIE grading, the most common mildly affected organ systems are pH, electrolyte imbalance and liver system, and the least affected organs are kidney and blood systems. Among children with HIE grade of mild and severe, there was no significant difference in moderate-severe organ involvement, and the number of severely affected children was small. CONCLUSION: With the increase of HIE severity, multi-organ involvement is aggravated. The organ involvement of HIE children with different degrees of severity is different.

Selenium-Directed ortho-C-H Borylation by Iridium Catalysis.

An iridium-catalyzed selenium-directed ortho-C-H borylation of benzyl selenide derivatives was successfully developed. This is the first example where selenium is used as a directing group in C-H borylation. The reaction was carried out using the tricyclohexylphosphine ligand for an improved catalytic efficiency. Various substrates were tolerated and afforded either ortho-monoborylated products (substrates bearing ortho- or meta-substituents) or diborylated products (substrates bearing para-substituents) in good yields. This study provides an efficient synthetic method for the preparation of a variety of organoselenium compounds.

Effects of Chelating Agents and Salts on Interfacial Properties and Lipid Oxidation in Oil-in-Water Emulsions.

The effects of chelating agents and salts on the interfacial characteristics and oxidative stability of oil-in-water emulsions containing an endogenous concentration of metal ions were investigated. Emulsions were fabricated by high-pressure homogenization of 10% oil phase (sacha inchi oil) and 90% aqueous phase (1% Tween 60 in phosphate buffer solution, pH 7, 50 mM). The oxidative stability of the emulsions was characterized by measuring peroxide values and thiobarbituric acid reactive substances throughout storage. Endogenous iron and copper ion levels in the emulsions were detected by atom absorption spectroscopy as 1.99 and 0.86 ppm, respectively. Incorporation of chelating agents, either ethylenediaminetetraacetic acid or sodium citrate, into the emulsions effectively inhibited lipid oxidation, showing that even these low levels of endogenous metal ions ( parts per million) were sufficient to promote oxidation. Conversely, the addition of monovalent salts, NaCl or KCl, slightly increased the rate of lipid oxidation in the emulsions, which was attributed to their impact on the physical properties of the surfactant layer at the oil droplet surfaces. The impact of chelating agents and salts on the electrical characteristics (ξ potential) and relaxation time (TR) of the surfactant-coated lipid droplets were characterized by particle electrophoresis and nuclear magnetic resonance spectroscopy, respectively. The chelating agents and salts altered the surface potential of the droplets, indicative of a change in the adsorption of metal ions to the droplet surfaces. Moreover, they altered the arrangement of surface-active molecules at the droplet surfaces, thereby impacting the contact of pro-/antioxidants with the oil phase. These results have important implications for the formulation of emulsion-based materials that are more stable to lipid oxidation.