Synergistic Photoredox and Iron Catalyzed 1,2-Thiosulfonylation of Alkenes with Thiophenols and Sulfonyl Chlorides.

Herein, a three-component 1,2-thiosulfonylation of alkenes with thiophenols and sulfonyl chlorides via synergistic photoredox and iron catalysis is described. Compared with previous studies, this protocol avoids tedious pre-synthesis of thiosulfonates and employs more readily accessible sulfonyl chlorides as a sulfonation reagent. Moreover, the reaction exhibits high compatibility with styrenes and unactivated alkenes as well as diverse sulfonyl chlorides, especially sulfamoyl chlorides. Preliminary mechanism investigations reveal that a radical pathway is involved in the catalytic cycle.

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.

Intermolecular 1,2-Difunctionalization of Terminal Alkynes to Access Trisubstituted Alkenes via Copper/Photoredox Dual Catalysis.

We report a copper metallaphotocatalytic 1,2-difunctionalization of terminal alkynes with N-hydroxyphthalimide (NHP) esters and readily available silyl reagents (TMSCN and TMSNCS) to access stereodefined trisubstituted alkenes, including (E)-alkenyl nitriles and thiocyanates. The reaction proceeds with excellent anti-stereoselectivity and demonstrates broad compatibility with a wide range of terminal alkynes and NHP esters as alkyl radical precursors. Experimental and computational studies have been performed to gain insight into the reaction mechanism.

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.

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.

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.

Coupling of Thiols and Aryl Halides Mediated by Dicyclohexano-18- crown-6 and Potassium Carbonate.

AIMS: A simple, transition-metal-free C-S coupling protocol for the synthesis of aryl thioethers is reported. BACKGROUND: Sulfur-containing moieties are ubiquitous in pharmaceutical drugs and materials and therefore methods for their construction are of great importance. One approach entails the catalytic coupling of an aryl halohydrocarbon with a thiol, but the transition metal catalysts usually used are prone to poisoning by participating sulfur species and efficient catalysis is usually only achieved after complex ligand optimization. OBJECTIVE: New transition-metal-free approaches to the synthesis of C-S bonds are urgently need. METHODS: We screened the reaction conditions such as alkali, crown ether, solvent, temperature, etc., tested the compatibility of the reaction substrate, and analyzed the mechanism process. RESULTS: The optimized reaction conditions were determined to be 1.0 equiv of aryl halides and 1.2 equiv of thiols at 110 ℃ in toluene with K2CO3 (1.5 equiv) as a base, promoted by 10 mol% dicyclohexano-18-crown-6. Up to 33 examples of thioethers were synthesized under transitionmetal- free conditions in good to excellent yields. CONCLUSION: We have developed a simple and efficient method for the C-S cross-coupling of a wide variety of (hetero)aryl halides and thiols mediated by dicyclohexano-18-crown-6 and without the need for transition-metal catalyst. In addition, the preparation and gram-scale experiments of a variety of drug molecules further verify the practicability of our developed method.

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.

A smartphone-based online tool for prehospital self-triage of COVID-19.

The COVID-19 epidemic has swept across China and spread to other countries. The rapid spreading of COVID-19 and panic combined with the lack of a hierarchical medical system in China have resulted in a huge number of hospital visiting which are overwhelming local medical system and increasing the incidence of cross infection. To meliorate this situation, we adopted the management concept of the system of Tiered Diagnosis and Treatment and developed an online tool for self-triage based on the mostly used multi-purpose smartphone app Wechat in China. This online tool helps people perform self-triage so that they can decide whether to quarantine at home or visit hospital. This tool further provides instructions for home quarantine and help patients make an appointment online if hospital visiting suggested. This smartphone application can reduce the burden on hospitals without losing the truly COVID-19 patients and protect people from the danger of cross infection.

Electrochemical Oxidative Esterification of Thiophenols: Efficient Access to Sulfinic Esters.

BACKGROUND: The sulfinic esters are important and useful building blocks in organic synthesis. OBJECTIVE: The aim of this study was to develop a simple and efficient method for the synthesis of sulfinic esters. MATERIALS AND METHODS: Constant current electrolysis from thiols and alcohols was selected as the method for the synthesis of sulfinic esters. RESULTS AND DISCUSSION: A novel electrochemical method for the synthesis of sulfinic esters from thiophenols and alcohols has been developed. Up to 27 examples of sulfinic esters have been synthesized using the current methods. This protocol shows good functional group tolerance as well as high efficiency. In addition, this protocol can be easily scaled up with good efficiency. Notably, heterocycle-containing substrates, including pyridine, thiophene, and benzothiazole, gave the desired products in good yields. A plausible reaction mechanism is proposed. CONCLUSION: This research not only provides a green and efficient method for the synthesis of sulfinic esters but also shows new applications of electrochemistry in organic synthesis. It is considered that this green and efficient synthetic protocol used to prepare sulfinic esters will have good applications in the future.

Promising Strategies for Overcoming BRAF Inhibitor Resistance Based on Known Resistance Mechanisms.

BACKGROUND: Almost 50% of metastatic melanomas harbor BRAF mutations. Since 2011, BRAF inhibitors have exhibited striking clinical benefits in BRAF-mutant melanoma patients. Unfortunately, their therapeutic effects are often temporary. The resistance mechanisms vary and can be broadly classified as MAPK reactivation-dependent and -independent. Elucidation of these resistance mechanisms provides new insights into strategies for overcoming resistance. Indeed, several alternative treatment strategies, including changes in the mode of administration, combinations of BRAF and MEK inhibitors, and immunotherapy have been verified as beneficial to BRAF inhibitor-resistant melanoma patients. Prospect: In this review, we discuss promising strategies for overcoming drug resistance and highlighting the prospects for discovering strategies to counteract BRAF inhibitor resistance.

Infection Control against COVID-19 in Departments of Radiology.

The COVID-19 epidemic, which is caused by the novel coronavirus SARS-CoV-2, has spread rapidly to become a world-wide pandemic. Chest radiography and chest CT are frequently used to support the diagnosis of COVID-19 infection. However, multiple cases of COVID-19 transmission in radiology department have been reported. Here we summarize the lessons we learned and provide suggestions to improve the infection control and prevention practices of healthcare workers in departments of radiology.

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.

Corona Virus International Public Health Emergencies: Implications for Radiology Management.

The outbreak of 2019 novel coronavirus (2019-nCoV) pneumonia was reported in Wuhan, Hubei Province, China in December 2019 and has spread internationally. This article discusses how radiology departments can most effectively respond to this public health emergency.

Photocatalytic site-selective C-H difluoroalkylation of aromatic aldehydes.

The direct photocatalyzed para-selective CAr-H difluoroalkylation of aromatic aldehyde derivatives has been accomplished using a newly explored catalytic system. In addition, when using para-substituted benzaldehydes as substrates, ortho-selective CAr-H difluoroalkylation was also accomplished. It is worth noting that all the above site-selectivity is opposite to traditional Friedel-Crafts reactions of aromatic aldehydes. The preliminary mechanistic investigations indicate that an electrophilic difluoroalkyl radical is involved in the catalytic cycle.

Carboxylate breaks the arene C-H bond via a hydrogen-atom-transfer mechanism in electrochemical cobalt catalysis.

Combined computational and experimental studies elucidated the distinctive mechanistic features of electrochemical cobalt-catalyzed C-H oxygenation. A sequential electrochemical-chemical (EC) process was identified for the formation of an amidylcobalt(iii) intermediate. The synthesis, characterization, cyclic voltammetry studies, and stoichiometric reactions of the related amidylcobalt(iii) intermediate suggested that a second on-cycle electro-oxidation occurs on the amidylcobalt(iii) species, which leads to a formal Co(iv) intermediate. This amidylcobalt(iv) intermediate is essentially a cobalt(iii) complex with one additional single electron distributed on the coordinating heteroatoms. The radical nature of the coordinating pivalate allows the formal Co(iv) intermediate to undergo a novel carboxylate-assisted HAT mechanism to cleave the arene C-H bond, and a CMD mechanism could be excluded for a Co(iii/i) catalytic scenario. The mechanistic understanding of electrochemical cobalt-catalyzed C-H bond activation highlights the multi-tasking electro-oxidation and the underexplored reaction channels in electrochemical transition metal catalysis.

Silver-Catalyzed Decarboxylative Alkylfluorination of Alkenes.

A decarboxylation of alkyl carboxylic acids for alkylfluorination of alkene was developed, with the catalysis of silver(I) and Selectfluor as both the oxidant and fluorine source. This reaction is highly chemoselective, producing the decarboxylative alkylfluorination products rather than the competitive fluorination of aliphatic carboxylic acids. This practical transformation proceeds efficiently in aqueous media at room temperature and exhibits a large range of functional-group tolerance in various primary and secondary aliphatic carboxylates and alkenes.

Electrochemical synthesis of 1,2-diketones from alkynes under transition-metal-catalyst-free conditions.

We report an electrochemical protocol for the direct oxidation of internal alkynes in air to provide 1,2-diketones. A variety of functional groups and heterocycle-containing substrates can be tolerated well under mild conditions.

Irradiation-Induced Cobaloxime-Catalyzed C-H Monofluoroalkylation of Styrenes at Room Temperature.

A cobaloxime-catalyzed photochemical synthesis of allyl monofluorides from styrenes is described herein. This method is characterized by mild reaction conditions, low-cost catalyst, and broad substrate scope. Furthermore, this convenient method will provide a facile synthesis toward novel monofluoroalkylated natural product and pharmaceutical derivatives. Mechanistic investigations indicate that a monofluoroalkyl radical is involved in the catalytic cycle.