Synthesis of Axially Chiral Biaryl-2-amines by PdII -Catalyzed Free-Amine-Directed Atroposelective C-H Olefination.

A simple and ubiquitously present group, free amine, is used as a directing group to synthesize axially chiral biaryl compounds by PdII -catalyzed atroposelective C-H olefination. A broad range of axially chiral biaryl-2-amines can be obtained in good yields with high enantioselectivities (up to 97 % ee). Chiral spiro phosphoric acid (SPA) proved to be an efficient ligand and the loading could be reduced to 1 mol % without erosion of enantiocontrol in gram-scale synthesis. The resulting axially chiral biaryl-2-amines also provide a platform for the synthesis of a set of chiral ligands.

Enantioselective Synthesis of Biaryl Atropisomers by Pd-Catalyzed C-H Olefination using Chiral Spiro Phosphoric Acid Ligands.

The discovery of proper ligands to simultaneously modulate the reactivity and effectively control the stereoselectivity is a central topic in the field of enantioselective C-H activation. Herein, we reported the synthesis of axially chiral biaryls by Pd-catalyzed atroposelective C-H olefination. A novel chiral spiro phosphoric acid, STRIP, was identified as a superior ligand for this transformation. A broad range of axially chiral quinoline derivatives were synthesized in good yields with excellent enantioselectivities (up to 98 % ee). Density functional theory was used to gain a theoretical understanding of the enantioselectivities in this reaction.

Clinical Challenges and Considerations in Management of Chronic Pain Patients During a COVID-19 Pandemic.

Since the coronavirus disease 2019 (COVID-19) was deemed a pandemic on 11 March 2020, we have seen exponential increases in the number of cases and deaths worldwide. The rapidly evolving COVID-19 situation requires revisions to clinical practice to defer non-essential clinical services to allocate scarce medical resources to the care of the COVID-19 patient and reduce risk to healthcare workers. Chronic pain patients require long-term multidisciplinary management even during a pandemic. Fear of abandonment, anxiety and depression may increase during this period of social isolation and aggravate pain conditions. Whilst physical consults for chronic pain patients were reduced, considerations including continuity of support and analgesia, telemedicine, allied health support and prioritising necessary pain services and interventions, were also taken to ensure biopsychosocial care for them. Chronic pain patients are mostly elderly with multiple comorbidities, and are more susceptible to morbidity and mortality from COVID-19. It is imperative to review pain management practices during the COVID-19 era with respect to infection control measures, re-allocation of healthcare resources, community collaborations, and analgesic use and pain interventions. The chronic pain patient faces a potential risk of functional and emotional decline during a pandemic, increasing healthcare burden in the long term. Clinical decisions on pain management strategies should be based on balancing the risks and benefits to the individual patient. In this commentary, we aim to discuss the basis behind some of the decisions and safeguards that were made at our tertiary pain centre over the last 6 months during the COVID-19 outbreak.

Palladium-Catalyzed Directed Atroposelective C-H Allylation via ß-H Elimination: 1,1-Disubstituted Alkenes as Allyl Surrogates.

Transition-metal-catalyzed dehydrogenative C-H allylation with 1,1-disubstituted alkenes via ß-H elimination remains challenging, because of the low reactivity and difficulty of controlling selectivity. Herein, the development of a Pd(II)-catalyzed directed atroposelective C-H allylation with methacrylates is described. Exclusive allylic selectivity was achieved. A vast array of axially chiral biaryl-2-amines are efficiently synthesized with excellent enantioselectivities (up to >99% enantiomeric excess).

Survey of neuromuscular monitoring and assessment of postoperative residual neuromuscular block in a postoperative anaesthetic care unit.

INTRODUCTION: The use of neuromuscular blocking agents (NMBAs) is common during general anaesthesia. Neuromuscular monitoring with a peripheral nerve stimulator (PNS) is essential to prevent postoperative residual neuromuscular block (PRNB), defined as a train-of-four (TOF) ratio < 0.9. PRNB remains a common complication and may contribute to morbidity in the postoperative anaesthetic care unit (PACU). METHODS: An online survey was sent to anaesthesiologists in our department to assess their knowledge and clinical practices related to neuromuscular blockade. Next, a study was conducted on adult patients scheduled for elective surgery under general anaesthesia requiring NMBAs. Upon admission to the PACU, TOF monitoring was performed. RESULTS: A large proportion of anaesthesiologists showed a lack of knowledge of neuromuscular blockade or non-adherence to the best clinical practices associated with it. The majority (98.7%) stated that they did not routinely use PNS monitoring. In the clinical study, TOF monitoring was only used in 17.9% of the 335 patients who were assessed. The prevalence of PRNB was 33.4% and was associated with the elderly (age ≥ 65 years), a higher dose of NMBA used, a shorter duration of surgery, and a shorter duration between the last dose of NMBA and measurement of PRNB in the PACU. The incidence of adverse symptoms in the PACU was observed to be higher in patients with PRNB. CONCLUSION: PRNB remains a clinically significant problem, but routine PNS monitoring is rare in our institution. This is compounded by inadequate knowledge and poor adherence to best clinical guidelines related to neuromuscular blockade.

A highly selective cascade approach to diverse aromatic ring systems from simple aromatic aldehydes and propiolates.

[reaction: see text] A new triethylamine-catalyzed cascade reaction of aromatic aldehydes with propiolates has been developed. This serial multi-bond-forming process furnishes diverse polycyclic aromatic hydrocarbons, including naphthalenes, phenanthrenes, benzofurans, and 2,3,9,9a-tetrahydronaphtha[2,3-b]furans. The chemical outcome of the process depends on the reaction temperature and can be tailored selectively by an appropriate choice of experimental conditions.

Novel and efficient synthesis of iminocoumarins via copper-catalyzed multicomponent reaction.

A variety of substituted iminocoumarins are prepared in good to excellent yields via a copper-catalyzed multicomponenet reaction of sulfonyl azides, terminal alkynes, and salicylaldehydes or o-hydroxylacetophenones. The method is general, mild, versatile, and efficient. A plausible mechanism for the domino process is proposed.

Optimizing detection sensitivity on surface-enhanced Raman scattering of transition-metal electrodes with confocal Raman microscopy.

Some points on how to improve the detection sensitivity of confocal Raman microscopy for the study of surface-enhanced Raman scattering (SERS) of transition-metal electrodes are discussed, including the careful design of the spectroelectrochemical cell, proper selection of the thickness of the solution layer, the binning of charge-coupled device (CCD) pixels, and appropriate setting of the notch filter. Various roughening methods for the Pt, Rh, Fe, Co, and Ni electrode surfaces have been introduced in order to obtain SERS-active surfaces. It has been shown that the appropriate roughening procedure and the optimizing performance of the confocal Raman microscope are the two most important factors to directly generate and observe SERS on net transition-metal electrodes.

Domino reaction of 3-(2-formylphenoxy)propenoates and amines: a novel synthesis of 1,4-dihydropyridines from salicaldehydes, ethyl propiolate, and amines.

A novel synthesis of Hantzsch-type N-substituted 1,4-dihydropyridines from salicaldehydes, ethyl propiolate, and amines has been developed. Salicaldehydes were treated with ethyl propiolate in the presence of N-methylmorpholine to give ethyl 3-(2-formylphenoxy)propenoates. Three equivalents of ethyl 3-(2-formylphenoxy)propenoates reacted with 1 equiv of amines under trifluoroacetic acid (TFA) catalyst to furnish the corresponding N-substituted 1,4-dihydropyridines in good to excellent yields, recovering the starting material salicaldehydes. A possible mechanism for the domino process was proposed. Furthermore, the products can be easily derived via further transformations and three of them exhibited strong fluorescence (Phif = 0.36-0.63).

Surface-enhanced Raman scattering from transition metals with special surface morphology and nanoparticle shape.

This discussion focuses on our recent approaches at aiming to optimize surface-enhanced Raman scattering (SERS) activity for transition metals (group VIII B elements), by intentionally fabricating desired surface nanostructures or synthesizing nanoparticles. The SERS activity of transition metals critically depends on the surface morphology of electrodes and on size, shape and aggregation form of nanoparticles. A correct surface roughening procedure for transition-metal electrodes is indispensable for fabricating cauliflower-like nanostructures that show a higher SERS activity. Two more methods have been explored to synthesize nanoparticles, i.e., cubic nanoparticles and gold-core palladium-shell nanostructures, respectively. Their SERS activities are considerably higher than those of normal spherical mono-metallic nanoparticles. To explain these observations, a preliminary theoretical calculation, using the three-dimensional finite difference time domain (3D-FDTD) method, was performed to evaluate the local electromagnetic field on transition metal surfaces. The result is in good agreement with the experimental data.

Parallel synthesis of strongly fluorescent polysubstituted 2,6-dicyanoanilines via microwave-promoted multicomponent reaction.

[reaction: see text] A facile parallel synthesis of polysubstituted 2,6-dicyanoanilines via microwave-promoted three-component reaction of aldehydes, ketones, and propanedinitrile in solution and also on polymer support has been developed. The screening for optical properties identified two new compounds with high fluorescence quantum yields.

Surface-enhanced Raman scattering in the ultraviolet spectral region: UV-SERS on rhodium and ruthenium electrodes.

We report the first observation of surface-enhanced Raman scattering (SERS) excited with ultraviolet (UV) light from transition metal electrodes. Adsorbed pyridine and SCN- on rough rhodium (Rh) and ruthenium (Ru) electrodes, respectively, have been studied using 325 nm laser excitation. In contrast, the best enhancers in the visible and near infrared, silver and gold, do not produce UV-SERS. The experimental data of UV-SERS are in agreement with our preliminary theoretical calculation based on the electromagnetic enhancement mechanism. The enhancement factor is about 2 orders of magnitude for the Rh and Ru electrodes when they are excited at 325 nm.