Flavin-Catalyzed Insertion of Oxygen into Rhenium-Methyl Bonds

Article discussing flavin-catalyzed insertion of oxygen into rhenium-methyl bonds

Intramolecular Hydroalkoxylation and Hydroamination of Alkynes Catalyzed by Cu(I) Complexes Supported by <i>N</i>‑Heterocyclic Carbene Ligands

Intramolecular addition of O–H and N–H bonds across carbon–carbon triple bonds to form 5- or 6-membered rings with exocyclic methylene groups for ether products and exocyclic methyl groups for imine products is catalyzed by (IPr)­Cu­(Me) (IPr = 1,3-bis­(2,6-diisopropylphenyl)-imidazol-2-ylidene). In a competition study, the cyclization of primary amines was found to be faster than that of alcohols. Kinetic studies for the conversion of 4-pentyn-1-ol reveal that the catalytic reaction is first-order in copper catalyst and zero-order in alkynyl alcohol, and an Eyring analysis yields Δ<i>H</i>^‡ = 18.7(4) kcal/mol and Δ<i>S</i>^‡ = −26(1) eu. The reaction of 5-phenyl-4-pentyn-1-ol provides (<i>Z</i>)-2-benzylidene-tetrahydrofuran in high yield and with quantitative stereoselectivity. Results from combined experimental and DFT studies are consistent with a mechanism that involves alkyne insertion into a Cu–O_alkoxide bond followed by protonolysis upon reaction with free alkynyl alcohol

Intramolecular Hydroalkoxylation and Hydroamination of Alkynes Catalyzed by Cu(I) Complexes Supported by <i>N</i>‑Heterocyclic Carbene Ligands

Intramolecular addition of O–H and N–H bonds across carbon–carbon triple bonds to form 5- or 6-membered rings with exocyclic methylene groups for ether products and exocyclic methyl groups for imine products is catalyzed by (IPr)­Cu­(Me) (IPr = 1,3-bis­(2,6-diisopropylphenyl)-imidazol-2-ylidene). In a competition study, the cyclization of primary amines was found to be faster than that of alcohols. Kinetic studies for the conversion of 4-pentyn-1-ol reveal that the catalytic reaction is first-order in copper catalyst and zero-order in alkynyl alcohol, and an Eyring analysis yields Δ<i>H</i>^‡ = 18.7(4) kcal/mol and Δ<i>S</i>^‡ = −26(1) eu. The reaction of 5-phenyl-4-pentyn-1-ol provides (<i>Z</i>)-2-benzylidene-tetrahydrofuran in high yield and with quantitative stereoselectivity. Results from combined experimental and DFT studies are consistent with a mechanism that involves alkyne insertion into a Cu–O_alkoxide bond followed by protonolysis upon reaction with free alkynyl alcohol

Global attitudes in the management of acute appendicitis during COVID-19 pandemic: ACIE Appy Study

Background: Surgical strategies are being adapted to face the COVID-19 pandemic. Recommendations on the management of acute appendicitis have been based on expert opinion, but very little evidence is available. This study addressed that dearth with a snapshot of worldwide approaches to appendicitis. Methods: The Association of Italian Surgeons in Europe designed an online survey to assess the current attitude of surgeons globally regarding the management of patients with acute appendicitis during the pandemic. Questions were divided into baseline information, hospital organization and screening, personal protective equipment, management and surgical approach, and patient presentation before versus during the pandemic. Results: Of 744 answers, 709 (from 66 countries) were complete and were included in the analysis. Most hospitals were treating both patients with and those without COVID. There was variation in screening indications and modality used, with chest X-ray plus molecular testing (PCR) being the commonest (19\ub78 per cent). Conservative management of complicated and uncomplicated appendicitis was used by 6\ub76 and 2\ub74 per cent respectively before, but 23\ub77 and 5\ub73 per cent, during the pandemic (both P < 0\ub7001). One-third changed their approach from laparoscopic to open surgery owing to the popular (but evidence-lacking) advice from expert groups during the initial phase of the pandemic. No agreement on how to filter surgical smoke plume during laparoscopy was identified. There was an overall reduction in the number of patients admitted with appendicitis and one-third felt that patients who did present had more severe appendicitis than they usually observe. Conclusion: Conservative management of mild appendicitis has been possible during the pandemic. The fact that some surgeons switched to open appendicectomy may reflect the poor guidelines that emanated in the early phase of SARS-CoV-2