Defluorinative Haloalkylation of Unactivated Alkenes Enabled by Dual Photoredox and Copper Catalysis.

A three-component defluorinative haloalkylation of alkenes with trifluoromethyl compounds and TBAX (X = Cl, Br) via dual photoredox/copper catalysis is reported. The mild conditions are compatible with a wide array of activated trifluoromethyl aromatics bearing diverse substituents, and various nonactivated terminal and internal alkenes, enabling straightforward access to synthetically valuable γ-gem-difluoroalkyl halides with high efficiency. Mechanistic studies indicate that the [Cu] complexes not only serve as XAT catalysts but also facilitate the SET reduction of trifluoromethyl groups by photocatalysts. Additionally, the resulting alkyl halide products can serve as versatile conversion intermediates for the synthesis of a diverse range of γ-gem-difluoroalkyl compounds.

Selective Defluoroalkylation and Hydrodefluorination of Trifluoromethyl Groups Photocatalyzed by Dihydroacridine Derivatives.

The selective functionalization of trifluoromethyl groups through C-F cleavage poses a significant challenge due to the high bond energy of the C(sp3)-F bonds. Herein, we present dihydroacridine derivatives as photocatalysts that can functionalize the C-F bond of trifluoromethyl groups with various alkenes under mild conditions. Mechanistic studies and DFT calculations revealed that upon irradiation, the dihydroacridine derivatives exhibit high reducibility and function as photocatalysts for reductive defluorination. This process involves a sequential single-electron transfer mechanism. This research provides valuable insights into the properties of dihydroacridine derivatives as photocatalysts, highlighting the importance of maintaining a planar conformation and a large conjugated system for optimal catalytic activity. These findings facilitate the efficient catalytic reduction of inert chemical bonds.

Palladium-catalyzed regioselective decarboxylative hydroarylation of alkynyl carboxylic acids with arylboronic acids.

The synthesis of (deuterated) 1,1-disubstituted alkenes via Pd-catalyzed decarboxylative hydroarylation of alkynyl carboxylic acids with arylboronic acids has been developed. The reaction features excellent regioselectivity, a broad substrate scope and gram-scale synthetic ability and offers a general synthetic method to synthesize 1,1-dideuterio olefins. Preliminary mechanism investigations indicate that 1,1-disubstituted alkenes are formed by hydroarylation of terminal alkynes generated by in situ decarboxylation of alkynyl carboxylic acids.

Direct Deoxyfluorination of Alcohols with KF as the Fluorine Source.

This report describes a method for the deoxyfluorination of alcohols with KF as the fluorine source via in situ generation of highly active CF3SO2F. Diverse functionalities, including halogen, nitro, ketone, ester, alkene, and alkyne, are well tolerated. Mild conditions, a short reaction time, and a wide substrate scope make this method an excellent choice for the construction of C-F bonds.

Protoboration of Alkynes and Miyaura Borylation Catalyzed by Low Loadings of Palladium.

The versions of Miyaura borylation and protoboration of alkynes catalyzed by low loadings of palladium (400 mol ppm = 0.04 mol %) have been developed. These transformations have a broad substrate scope, good functional-group compatibility, and gram-scale synthetic ability.

Electrochemical Trifluoromethylation of Thiophenols with Sodium Trifluoromethanesulfinate.

We developed an electrochemical trifluoromethylation of thiophenols without the use of metal catalysts and oxidants. This reaction features mild reaction conditions, readily available substrate, as well as moderate to good yields. In addition, this protocol can be easily scaled up with moderate efficiency.

Loopholes in Current Infection Control and Prevention Practices Against COVID-19 in Radiology Department and Improvement Suggestions.

OBJECTIVES: To improve the infection control and prevention practices against coronavirus disease 2019 (COVID-19) in radiology department through loophole identification and providing rectifying measurements. METHODS: Retrospective analysis of 2 cases of health-care-associated COVID-19 transmission in 2 radiology departments and comparing the infection control and prevention practices against COVID-19 with the practices of our department, where no COVID-19 transmission has occurred. RESULTS: Several loopholes have been identified in the infection control and prevention practices against COVID-19 of the 2 radiology departments. Loopholes were in large part due to our limited understanding of the highly contagious coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which is characterized by features not observed in other SARS viruses. We recommend to set up an isolation zone for handling patients who do not meet the diagnostic criteria of COVID-19 but are not completely cleared of the possibility of infection. CONCLUSIONS: Loopholes in the infection control and prevention practices against COVID-19 of the 2 radiology departments are due to poor understanding of the emerging disease which can be fixed by establishing an isolation zone for patients not completely cleared of SARS-CoV-2 infection.

CT Imaging and Differential Diagnosis of COVID-19.

Since the beginning of 2020, coronavirus disease 2019 (COVID-19) has spread throughout China. This study explains the findings from lung computed tomography images of some patients with COVID-19 treated in this medical institution and discusses the difference between COVID-19 and other lung diseases.

Electrochemical C-O Bond Formation: Facile Access to Aromatic Lactones.

An efficient and robust methodology based on electrochemical techniques for the direct synthesis of aromatic lactones through dehydrogenative C-O cyclization is described. This new and useful electrochemical reaction can tolerate a variety of functional groups, and is scalable to 100 g under mild conditions. Remarkably, heterocycle-containing substrates can be employed, thus expanding the scope of radical C-O cyclization reactions.

Cu(II)-Mediated Decarboxylative Trifluoromethylthiolation of α,ß-Unsaturated Carboxylic Acids.

A tunable method for the direct trifluoromethylthiolation of α,ß-unsaturated carboxylic acids was developed to afford trifluoromethylthiolated ketones or alkenes. The reaction proceeds smoothly under mild conditions and shows an excellent functional group tolerance.

Modification, Biological Evaluation and SAR Studies of Novel 1H-Pyrazol Derivatives Containing N,N'-Disubstituted Urea Moiety as Potential Anti-melanoma Agents.

Malignant melanomas are amongst the most aggressive cancers. BRAF Inhibitors have exhibited therapeutic effects against BRAF-mutant melanoma. In continuation of our earlier studies on anti-melanoma agents based on 1H-pyrazole skeleton, two sets of novel compounds that include 1H-pyrazole-4-amines FA1 - FA13 and corresponding urea derivatives FN1 - FN13 have been synthesized and evaluated for their BRAFV600E inhibitory and antiproliferation activities. Compound FN10 displayed the most potent biological activity against BRAFV600E (IC50 = 0.066 µm) and the A375 human melanoma cell line (GI50 = 0.81 µm), which was comparable to the positive control vemurafenib, and more potent than our previously reported 1H-pyrazole-3-amines and their urea derivatives. The results of SAR studies and molecular docking can guide further optimization and may help to improve potency of these pyrazole-based anti-melanoma agents.

Visible-Light-Induced C2 Alkylation of Pyridine N-Oxides.

A photoredox catalytic method has been developed for the direct C2 alkylation of pyridine N-oxides. This reaction is compatible with a range of synthetically relevant functional groups for providing efficient synthesis of a variety of C2-alkylated pyridine N-oxides under mild conditions. Mechanistic studies are consistent with the generation of a radical intermediate along the reaction pathway.

Visible-Light-Promoted C-H Arylation by Merging Palladium Catalysis with Organic Photoredox Catalysis.

The use of a dual palladium/organic photoredox catalytic system enables the directed arylation of arenes with aryldiazonium salts with a broad substrate scope at room temperature under mild reaction conditions. This study thus serves as not only an alternative route for the biaryl motifs but also a new example for the application of an organic photoredox catalyst.

Copper(i)-catalyzed ring-opening cyanation of cyclopropanols.

A copper(i)-catalyzed ring-opening cyanation of cyclopropanols was developed. The reaction provides an alternative method to achieve ß-cyano ketones efficiently. This reaction exhibits good functional group compatibility under mild conditions and can be scaled up to the gram scale. Preliminary mechanistic studies suggest that the reaction might go through a free radical process.

Resveratrol-based cinnamic ester hybrids: synthesis, characterization, and anti-inflammatory activity.

Twenty-three novel resveratrol-based cinnamic ester hybrids were designed and synthesized. All the compounds were evaluated for their anti-inflammatory activity using RAW264.7 cells. Among them, compound D15 was found to be the most potent one in inhibiting NO production in LPS-stimulated RAW264.7 cells. The further study indicated that compound D15 could suppress expression of proteins iNOS, COX-2, p-p65, and p-IκB LPS-induced. Immunofluorescence further revealed compound D15 could reduce activation p65 in nuclei. All the results indicated that the anti-inflammatory activity of title compound may partly due to its inhibitory effect on the NF-κB signaling pathway.

Silver-promoted decarboxylative amidation of α-keto acids with amines.

A general and effective method for the synthesis of amides through decarboxylative amidation of α-keto acids with amines has been developed. The reaction proceeded smoothly to afford the corresponding amide products in good yield under air and shows excellent functional group tolerance. In addition, the protocol can be further applied in the synthesis of heterocyclic compounds like benzimidazoles.

KI-catalyzed α-acyloxylation of acetone with carboxylic acids.

The KI-catalyzed reaction of acetone with aromatic carboxylic acids is achieved, leading to α-acyloxycarbonyl compounds in good to excellent yields under mild reaction conditions. The present method exhibits good functional-group compatibility. Notably, this reaction system is even suitable for cinnamic acid, 3-phenylpropiolic acid and 4-phenylbutanoic acid. A kinetic isotope effect (KIE) study indicates that C-H cleavage of the acetone is the rate-limiting step in the catalytic cycle.

Transition-Metal-Free Synthesis of Ynones via Decarboxylative Alkynylation of α-Keto Acids under Mild Conditions.

A transition-metal-free synthetic method of various ynones via decarboxylative alkynylation of α-keto acids is described. The reaction is carried out under mild conditions and exhibits remarkable tolerance of functional groups. The mechanism of a radical process is proposed in the reaction.

Silver-catalyzed C(sp2)-H functionalization/C-O cyclization reaction at room temperature.

Silver-catalyzed C(sp(2))-H functionalization/C-O cyclization has been developed. The scalable reaction proceeds at room temperature in an open flask. The present method exhibits good functional-group compatibility because of the mild reaction conditions. Using a AgNO3 catalyst and a (NH4)2S2O8 oxidant in CH2Cl2/H2O solvent, various lactones are obtained in good to excellent yields. A kinetic isotope effect (KIE) study indicates that the reaction may occur via a radical process.

Copper-catalysed ring-opening trifluoromethylation of cyclopropanols.

A copper-catalysed ring-opening trifluoromethylation reaction of cyclopropanols has been developed. Various ß-trifluoromethyl ketones are obtained in good to excellent yields under mild reaction conditions. The present method also exhibits good functional-group compatibility. The mechanism of this new ring-opening trifluoromethylation reaction was investigated by radical trapping reactions.