COVID-19 pandemic effects on health worker's mental health: Systematic review and meta-analysis.

Background: Healthcare workers (HCWs) exposed to coronavirus 19 (COVID-19) are at high risk of developing mental health concerns across several domains. The aim of this study is to determine the updated, global frequency of these outcomes.

Methods: A multistep literature search was performed from database inception until March 1, 2021.

Exploiting Carbonyl Groups to Control Intermolecular Rhodium-Catalyzed Alkene and Alkyne Hydroacylation.

Readily available β-carbonyl-substituted aldehydes are shown to be exceptional substrates for Rh-catalyzed intermolecular alkene and alkyne hydroacylation reactions. By using cationic rhodium catalysts incorporating bisphosphine ligands, efficient and selective reactions are achieved for β-amido, β-ester, and β-keto aldehyde substrates, providing a range of synthetically useful 1,3-dicarbonyl products in excellent yields. A correspondingly broad selection of alkenes and alkynes can be employed.

Sequential catalysis: exploiting a single rhodium(i) catalyst to promote an alkyne hydroacylation-aryl boronic acid conjugate addition sequence.

We demonstrate that a single Rh(i) complex can promote two mechanistically distinct C-C bond-forming reactions - alkyne hydroacylation and aryl boronic acid conjugate addition - to deliver substituted ketone products from the controlled assembly of three readily available fragments. This is a rare example of a Rh(i)/Rh(iii) cycle and a redox neutral Rh(i) cycle being promoted by a single catalyst. The process is broad in scope, allowing significant variation of all three reaction components.

Synthesis of Pyrrolo[2,3-d]pyrimidines by Copper-Mediated Carbomagnesiations of N-Sulfonyl Ynamides and Application to the Preparation of Rigidin A and a 7-Azaserotonin Derivative.

The treatment of readily available N-alkynyl-5-iodo-6-sulfamido-pyrimidines with iPrMgCl⋅LiCl followed by a transmetalation with CuCN⋅2 LiCl produces, after intramolecular carbocupration, metalated pyrrolo[2,3-d]pyrimidines. Quenching of these pyrimidines with allylic halides or acid chlorides results in polyfunctional pyrrolo[2,3-d]pyrimidines. Further reaction with ICl and a Negishi cross-coupling, using PEPPSI-iPr as the catalyst, furnishes fully substituted N-heterocycles.

Well-Defined and Robust Rhodium Catalysts for the Hydroacylation of Terminal and Internal Alkenes.

A Rh-catalyst system based on the asymmetric ligand (t)Bu2PCH2P(o-C6H4OMe)2 is reported that allows for the hydroacylation of challenging internal alkenes with β-substituted aldehydes. Mechanistic studies point to the stabilizing role of both excess alkene and the OMe-group.

Enantioselective Synthesis of Tertiary Propargylic Alcohols under N-Heterocyclic Carbene Catalysis.

A straightforward procedure to carry out the enantioselective benzoin reaction between aldehydes and ynones by employing a chiral N-heterocyclic carbene (NHC) as catalyst was developed. Under the optimized reaction conditions, these ynones undergo a clean and selective 1,2-addition with the catalytically generated Breslow intermediate, not observing any byproduct arising from competitive Stetter-type reactivity. This procedure allows the preparation of tertiary alkynyl carbinols as highly enantioenriched materials, which have the remarkable potential to be used as chiral building blocks in organic synthesis.

New in situ trapping metalations of functionalized arenes and heteroarenes with TMPLi in the presence of ZnCl2 and other metal salts.

The addition of TMPLi to a mixture of an aromatic or heteroaromatic substrate with a metal salt such as MgCl2, ZnCl2, or CuCN at -78 °C first leads to lithiation of the arene followed by transmetalation with the metal salt to afford functionalized organometallic compounds of Mg, Zn, or Cu. This in situ trapping method allows an expedited metalation (-78 °C, 5 min) of a range of sensitive pyridines (bearing a nitro, ester, or cyano group) and allows the preparation of kinetic regioisomers of functionalized aromatic compounds or heterocycles not otherwise available by standard metalating agents, such as TMPMgCl⋅LiCl or TMPZnCl⋅LiCl.

Ethyl glyoxylate N-tosylhydrazone as sulfonyl-transfer reagent in base-catalyzed sulfa-Michael reactions.

Ethyl glyoxylate N-tosylhydrazone has been identified as an excellent sulfonyl anion surrogate in the DBU-catalyzed conjugate addition reaction with enones and enals for the synthesis of functionalized sulfones. The reaction proceeds under base-catalyzed conditions and provides a direct access to γ-keto- and γ-hydroxy sulfones in a simple and reliable way through a sulfa-Michael reaction that proceeds with high yield and chemoselectivity.

Enantioselective conjugate addition of donor-acceptor hydrazones to α,β-unsaturated aldehydes through formal diaza-ene reaction: access to 1,4-dicarbonyl compounds.

Donor-acceptor monosubstituted hydrazones participate as suitable reagents able to undergo an enantioselective formal diaza-ene reaction with α,β-unsaturated aldehydes under chiral secondary amine catalysis. This constitutes a new approach for the enantioselective conjugate addition of hydrazones to enals under metal-free conditions and leads to the formation of γ-hydrazono carboxylic acids after oxidation/[1,3]-H shift. The methodology is also useful for the synthesis of enantioenriched β-substituted α-keto-1,5-diesters by using the hydrazone moiety as a masked carbonyl group.

Organocatalytic enantioselective synthesis of 2,3-dihydropyridazines.

We have developed an efficient procedure for the easy and straightforward preparation of functionalized dihydropyridazines as highly enantiopure materials by reaction of pyruvaldehyde 2-tosyl hydrazone with a variety of α,β-unsaturated aldehydes using a chiral secondary amine as catalyst. The overall process consists of a cascade reaction involving an initial aza-Michael reaction, in which the stereocentre is installed, followed by an intramolecular aldol reaction/dehydration step.