Oxidative trifluoromethoxylation reaction of C-H bond
As an important class of compounds, fluorine-containing organic compounds are widely used in the fields of medicine, pesticides, and functional materials. The direct functionalization of C-H bonds to introduce fluorine atoms or fluorine-containing groups is a very efficient method for synthesizing such compounds. In recent years, significant progress has been made in the fluorination, trifluoromethylation and trifluoromethylthiolation of C-H bonds. In contrast, the trifluoromethoxylation reaction based on CH bond activation, because the trifluoromethoxy anion is very unstable, it is easy to decompose to generate difluorophosgene and fluorine anion, and it lacks effective synthesis of trifluoromethoxy reagent method, the oxidative trifluoromethoxylation reaction of the CH bond has always been a difficult problem.
Scientists discover elemental fluorine under natural conditions
Fluorine is the most active chemical element, that is why it does not exist in it’s elemental form in nature, but only exists in compounds such as fluorite, a special kind of fluorite, namely "foul fluorite" or "antozonite" , this mineral emits a strong smell when crushed. Many outstanding chemists, like Friedrich Woehler (1800-1882) and Justus von Liebig (1803-1873), proposed various substances to explain the smell. Over the years, scientists have used olfactory tests, chemical analysis, and complex mass spectrometry studies-reaching very different conclusions. Recently, scientists at the Technical University of Munich (TUM) and Ludwig-Maximilian-University of Munich (LMU) successfully discovered the natural element fluorine in this fluorite for the first time. The scientific team led by Florian Kraus, head of the Fluorochemistry Working Group of the Department of Chemistry at Technianche Universitaet Muenchen, and Joern Schmedt auf der Guenne, head of the Solid State Nuclear Magnetic Resonance Lemmén-Knott working group at the Ludwig-Maximilian University of Munich The Department of Chemistry directly proved the existence of fluorine in "antozonite". Using 19F-NMR spectroscopy, they were able to identify fluorine "in situ", that is, non-destructively identifying fluorine in its natural environment, thus ending the long-term discussion about the odor of "stinky fluorite. The researchers explained: “it’s not surprising that chemists suspect the presence of element fluorine in fluorite.”“The fact that the elements fluorine and calcium found side by side here usually react with each other is really unbelievable.”However, in“antozonite”, there are very special conditions: elemental fluorine is produced by tiny uranium inclusions in minerals, which continuously emit ionizing radiation and thus decompose fluorite into calcium and elemental fluorine. Fluorine remains in tiny inclusions and is separated from calcium by non-reactive fluorite, thereby maintaining its elemental form. Ionizing radiation also causes the formation of calcium clusters, which makes "antozonite" dark.
Amgen bispecific antibody therapy phase III Linchuan results announced reduce the risk of disease
Acute lymphocytic leukemia (B-ALL) is the most common leukemia in children. B-cell ALL makes children more susceptible to infection because cancerous B cells cannot perform their immune functions normally. Although existing therapies can cure most ALL patients, once the patient relapses, the prognosis drops rapidly, especially for high-risk ALL patients.
Fosun Pharma's mRNA COVID-19 vaccine is approved for emergency use in Hong Kong
The mRNA COVID-19 vaccine was obtained by Fosun Pharma signed a license agreement with BioNTech SE of Germany on March 13, 2020. Fosun Pharma has the exclusive rights to develop and commercialize mRNA COVID-19 vaccine in Mainland China, Hong Kong, Macau and Taiwan.
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