A copper‐catalyzed multicomponent coupling reaction between in situ generated ortho‐arynes, terminal alkynes, and carbon dioxide was developed to access isocoumarins in moderate to good yields. The ...key to this CO2‐incorporating reaction was the use of a versatile N‐heterocyclic carbene/copper complex that was able to catalyze multiple transformations within the three‐component reaction.
A facile synthetic protocol to isocoumarins consists of a three‐component coupling reaction between 1‐alkynes, 2‐(trimethylsilyl)aryl triflates, and CO2 (see scheme). The key to this reaction was the use of a versatile N‐heterocyclic carbene/copper complex that was able to catalyze multiple transformations within the three‐component reaction.
The reductive formylation of amines using CO2 and hydrosilanes is an attractive method for incorporating CO2 into valuable organic compounds. However, previous systems required either high catalyst ...loadings or high temperatures to achieve high efficiency, and the substrate scope was mostly limited to simple amines. To address these problems, a series of alkyl bridged chelating bis(NHC) rhodium complexes (NHC=N‐heterocyclic carbene) have been synthesized and applied to the reductive formylation of amines using CO2 and Ph2SiH2. A rhodium‐based bis(tzNHC) complex (tz=1,2,3‐triazol‐5‐ylidene) was identified to be highly effective at a low catalyst loading and ambient temperature, and a wide substrate scope, including amines with reducible functional groups, were compatible.
Beyond the norm: Rhodium complexes bearing a strong electron‐donating bis(1,2,3‐triazol‐5‐ylidene) ligand were found to be excellent catalysts for the reductive formylation of amines with CO2 and Ph2SiH2 at ambient temperature. The catalyst system possesses a broad substrate scope which tolerates a variety of reducible functional groups and is suitable for the synthesis of bioactive compounds. Tf=trifuoromethanesulfonyl.
C7‐Arylated pyrazolo1,5‐aazines are important structural motifs with profound applications in drug and material research. Here, we report a general and straighforward synthesis of these ...bi(hetero)aryls via palladium‐catalyzed direct C−H arylation, employing low‐cost and abundant (hetero)aryl chlorides as the aryl source. The catalytic system is robust and covers a wide substrate scope regarding heteroarenes as well as (hetero)aryl chlorides, with possible extension to the C−H arylation of 1,2,4triazolo1,5‐apyrimidines. This study also presents a rare example of using (hetero)aryl chlorides for the direct C−H arylation of six‐membered heteroarenes.
A new protocol for the palladium‐catalyzed C−H arylation of pyrazolo1,5‐aazines, using low‐cost and abundant (hetero)aryl chlorides as the coupling partners, and without any stoichiometric metal additives is reported. The structural motif of coupling products can be found in many drugs and organic materials.
Summary
Oral bisphosphonates are effective medications for the prevention of fractures in people suffering from osteoporosis. They are associated with gastrointestinal adverse reactions the most ...severe being an esophageal ulcer. It is unclear if oral bisphosphonates have a similar gastrointestinal safety profile in the hospital setting as in the community setting because hospitalized patients are often bedridden which may hinder proper drug administration.
Introduction
To evaluate the incidence of upper gastrointestinal symptoms in hospitalized patients taking oral bisphosphonate.
Methods
This single-center prospective cohort study included hospitalized adult patients actively taking risedronate or alendronate. Upper gastrointestinal symptoms were actively assessed at the baseline and 1 to 5 h following the administration of the oral bisphosphonate.
Results
A total of 298 patients were included in the study. The mean age was 64 ± 15 years. During the follow-up period, gastric and esophageal symptoms affected 32 patients (10.7%). Epigastric burning, dysphagia, and regurgitation were reported in 4.4% (
n
= 13), 3% (
n
= 9), 2.7 (
n
= 8), and 2.3% (
n
= 7) patients, respectively. Heartburn, retro-sternal pain, and odynophagia were observed in 1.7% (
n
= 5), 1.7% (
n
= 5), and 0.3% (
n
= 1) patients.
Conclusion
The incidence of adverse reaction was similar to that reported in community trials. The administration of oral bisphosphonate in hospitalized patients does not represent an additional risk for upper gastrointestinal adverse events. Treatment should be optimized during the hospital stay to improve the pharmacological management of osteoporosis.
NHC‐rhodium complexes (NHC=N‐heterocyclic carbenes) have been widely used as efficient catalysts for hydrosilylation reactions. However, the substrates were mostly limited to reactive carbonyl ...compounds (aldehydes and ketones) or carbon‐carbon multiple bonds. Here, we describe the application of newly‐developed chelating bis(tzNHC)‐rhodium complexes (tz=1,2,3‐triazol‐5‐ylidene) for several reductive transformations. With these catalysts, the formal reductive methylation of amines using carbon dioxide, the hydrosilylation of amides and carboxylic acids, and the reductive alkylation of amines using carboxylic acids have been achieved under mild reaction conditions.
A one-pot, sequential process that combines a trans-selective hydroalumination of propargyl alcohols and amines with a copper- or silver-catalyzed carboxylation reaction using carbon dioxide, ...followed by an acid-mediated intramolecular condensation step, led to the formation of a wide range of α,β-unsaturated γ-butyrolactones and lactams.
A new pandemic coronavirus causing coronavirus disease-2019 (COVID-19), initially called 2019-nCoV and successively named Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The COVID-19 ...refers to the disease while the SARS-CoV-2 refers to the virus and is characterized by a rapid contagious capacity able to spread worldwide in a very short time. The rise in the number of infected patients and deaths is of great concern especially because symptoms are vague and similar to other forms of flu infection and corona syndrome infections characterized by fever, fatigue, dry cough, and dyspnea. According to the latest guidelines published by the World Health Organization (WHO), the diagnosis of COVID-19 must be confirmed by quantitative reverse transcription polymerase chain reaction (rRT-PCR) or gene sequencing of specimen obtained from throat, sputum and blood samples. However, the limitations due to logistics, as well as low sensitivity and specificity diagnostic tools currently available have been reported as the main cause of high incidence of either false-negative or positive results.
The purpose of the present translational research protocol is to discuss and present the original findings from our research team on new diagnostic technique to detect four Coronaviridae family members (SARS-CoV-2, SARS-CoV, HCoV and MERS-CoV), highlighting the methodology, the procedure and the possible advantages. Moreover, the authors review the current epidemiology, precautions and safety measures for health personnel to manage patients with known or suspected COVID-19 infection.
Implementation of an effective and rapid plan of diagnosing, screening and checking is a key factor to reduce and prevent further transmission. This procedure based on rRT-PCR could be of great help to decisively validate the results obtained from more conventional diagnostic procedures such as chest computed tomography (CT) imaging and chest ultrasound.
This translational diagnostic tool will assist emergency and primary care clinicians, as well as out-of-hospital providers, in effectively managing people with suspected or confirmed SARS-CoV-2.
The first organocatalysed, metal-free cross-nucleophile coupling of indoles with α-branched aldehydes forming acyclic stereoselective quaternary carbon centres is presented. Applying an amino ...acid-derived catalyst with suitable organic oxidants affords the desired enantioenriched indole functionalised products with moderate to excellent yield and enantioselectivity. Two metal-free oxidative protocols employing either DDQ or a sequential approach that uses two organocatalysts to facilitate the use of O
2
as the terminal oxidant are disclosed. These methods are compatible with various indoles ranging from electron-rich to -deficient substituents at the C-2, -5, -6, and -7-positions reacting with a series of different α-branched aldehydes.
The first organocatalysed, metal-free cross-nucleophile coupling of indoles with α-branched aldehydes forming acyclic stereoselective quaternary carbon centres is presented.
In this study, chromium (Cr) retention by the mangroves in the Thi Vai catchment located in the south of Vietnam was simulated using a coupled model of the hydrodynamic model Delft3D with Cr ...transport and a model for the uptake of Cr by mangroves. This coupled model was calibrated and validated using data from four hydrodynamic stations and data from phytoremediation studies. To analyze the effect of mangroves on reducing Cr pollution, three scenarios were run by the model. Scenario 1 (SC1) is based on the actual situation concerning discharges and the distribution of mangroves. Scenario 2 (SC2) simulates the deterioration of the actual situation by deforestation on the west bank and the establishment of more industrial zones on the east bank. Scenario 3 (SC3) simulates an eco-friendly development comprising the channeling of wastewater through constructed wetlands with mangroves prior to the discharge into the river. Simulation results showed that the total Cr uptake by mangroves in SC3 was higher than in the other two scenarios. In total, 33 kg Cr in water were absorbed by the constructed wetlands in SC3 within one month. The simulation results helped in overcoming the difficulties and challenges in assessing the capacity of mangrove forests on the retention of chromium at catchment scale.
We describe an electrochemical immunosensor based on functionalization of a working electrode by electrografting two functional diazonium salts. The first one is a molecular probe, diclofenac, ...coupled with an arylamine onto which a specific antibody is immobilized by affinity interactions; the second is a redox probe (a quinone) also coupled with an arylamine, able to transduce the hapten-antibody association into a change in electroactivity. The steric hindrance induced by the antibody leads to a current decrease upon binding of the antibody on the grafted molecular probe; conversely, when diclofenac is present in solution, a displacement equilibrium occurs between the target diffusing into the solution and the grafted probe. This leads to dissociation of the antibody from the electrode surface, event which is transduced into a current increase (“signal-on” detection). The detection limit is ca. 20 fM, corresponding to 6pgL−1 diclofenac, which is competitive compared to other label-free immunosensors. We demonstrate that the sensor is selective and is able to quantify diclofenac in tap water.
Display omitted
•Competitive electrochemical immunosensor for diclofenac detection.•Limit of detection of 0.1 pM.•Selective towards structural analogues.•Works on real samples and in tap water.
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