Copper-catalyzed functionalization of enynes Dherbassy, Quentin; Manna, Srimanta; Talbot, Fabien J. T ...
Chemical science (Cambridge),
10/2020, Letnik:
11, Številka:
42
Journal Article
Recenzirano
Odprti dostop
The copper-catalyzed functionalization of enyne derivatives has recently emerged as a powerful approach in contemporary synthesis. Enynes are versatile and readily accessible substrates that can ...undergo a variety of reactions to yield densely functionalized, enantioenriched products. In this perspective, we review copper-catalyzed transformations of enynes, such as boro- and hydrofunctionalizations, copper-mediated radical difunctionalizations, and cyclizations. Particular attention is given to the regiodivergent functionalization of 1,3-enynes, and the current mechanistic understanding of such processes.
The copper-catalyzed functionalization of enynes is a powerful approach to yield densely functionalized products. This review covers various transformations, such as boro- and hydrofunctionalizations, copper-mediated radical difunctionalizations, and cyclizations.
An interrupted Pummerer/nickel‐catalysed cross‐coupling strategy has been developed and used in the elaboration of styrenes. The operationally simple method can be carried out as a one‐pot process, ...involves the direct formation of stable alkenyl sulfonium salt intermediates, utilises a commercially available sulfoxide, catalyst, and ligand, operates at ambient temperature, accommodates sp‐, sp2‐, and sp3‐hybridised organozinc coupling partners, and delivers functionalised styrene products in high yields over two steps. An interrupted Pummerer/cyclisation approach has also been used to access carbo‐ and heterocyclic alkenyl sulfonium salts for cross‐coupling.
Feel free to interrupt: Styrenes were activated under metal‐free conditions by an interrupted Pummerer process. The resulting stable alkenyl sulfonium salts underwent nickel‐catalysed cross‐coupling under simple, mild conditions. The versatile sequence could be carried out as a one‐pot process with a range of organozinc partners to form di‐, tri‐, and tetrasubstituted alkene products.
Copper‐catalyzed borylative multicomponent reactions (MCRs) involving olefins and C−N electrophiles are a powerful tool to rapidly build up molecular complexity. The products from these reactions ...contain multiple functionalities, such as amino, cyano and boronate groups, that are ubiquitous in medicinal and process chemistry programs. Copper‐catalyzed MCRs are particularly attractive because they use a relatively abundant and non‐toxic catalyst to selectively deliver high‐value products from simple feedstocks such as olefins. In this Minireview, we explore this rapidly emerging field and survey the borylative union of allenes, dienes, styrenes and other olefins, with imines, nitriles and related C−N electrophiles.
Copper‐catalyzed borylative multicomponent couplings, involving olefins and C−N electrophiles, constitute an efficient approach to high‐value amine and nitrile products. This Minireview assesses the progress in this rapidly emerging field and surveys the borylative union of allenes, dienes, styrenes, and related olefins, with imines, nitriles, and related electrophiles.
Copper-catalyzed coupling of readily available ketiminoesters, allenes, and a diboron affords densely functionalized quaternary α-amino esters bearing adjacent stereocenters and versatile vinyl ...boronate motifs. The method utilizes a commercially available copper(I) catalyst, operates at ambient temperature, and features a catalytic allyl cupration of ketiminoesters.
Benzocyclobutenes (BCBs) are of growing interest in materials and medicinal chemistry, although general routes for their provision remain underexplored. A modular, divergent, and stereoselective Cu- ...and Pd-catalyzed assembly/cyclization sequence allows the synthesis of densely functionalized BCBs, from readily accessible imine, allene, and diboron precursors. Preliminary results have identified enantioselective conditions for our protocol and highlighted, for example, its applicability to the synthesis of BCB-containing peptides. By simple variation of experimental conditions or substrate modification, our strategy was expanded to deliver indoline and quinoline derivatives, suitable for further manipulations.
Copper‐catalyzed borylative multicomponent reactions (MCRs) involving olefins and C−N electrophiles are a powerful tool to rapidly build up molecular complexity. The products from these reactions ...contain multiple functionalities, such as amino, cyano and boronate groups, that are ubiquitous in medicinal and process chemistry programs. Copper‐catalyzed MCRs are particularly attractive because they use a relatively abundant and non‐toxic catalyst to selectively deliver high‐value products from simple feedstocks such as olefins. In this Minireview, we explore this rapidly emerging field and survey the borylative union of allenes, dienes, styrenes and other olefins, with imines, nitriles and related C−N electrophiles.
Copper‐catalyzed borylative multicomponent couplings, involving olefins and C−N electrophiles, constitute an efficient approach to high‐value amine and nitrile products. This Minireview assesses the progress in this rapidly emerging field and surveys the borylative union of allenes, dienes, styrenes, and related olefins, with imines, nitriles, and related electrophiles.
An interrupted Pummerer/nickel‐catalysed cross‐coupling strategy has been developed and used in the elaboration of styrenes. The operationally simple method can be carried out as a one‐pot process, ...involves the direct formation of stable alkenyl sulfonium salt intermediates, utilises a commercially available sulfoxide, catalyst, and ligand, operates at ambient temperature, accommodates sp‐, sp2‐, and sp3‐hybridised organozinc coupling partners, and delivers functionalised styrene products in high yields over two steps. An interrupted Pummerer/cyclisation approach has also been used to access carbo‐ and heterocyclic alkenyl sulfonium salts for cross‐coupling.
Synthese mit Unterbrechung: Styrole werden unter metallfreien Bedingungen mithilfe eines unterbrochenen Pummerer‐Prozesses aktiviert, und die resultierenden stabilen Alkenylsulfoniumsalze gehen eine Nickel‐katalysierte Kreuzkupplung unter milden Bedingungen ein. Die vielseitige Sequenz wurde als Eintopfreaktion mit einer Bandbreite von Organozink‐Partnern unter Bildung von di‐, tri‐ und tetrasubstituierten Alkenen durchgeführt.
To characterize associations between exposures within and outside the medical workplace with healthcare personnel (HCP) SARS-CoV-2 infection, including the effect of various forms of respiratory ...protection.
Case-control study.
We collected data from international participants via an online survey.
In total, 1,130 HCP (244 cases with laboratory-confirmed COVID-19, and 886 controls healthy throughout the pandemic) from 67 countries not meeting prespecified exclusion (ie, healthy but not working, missing workplace exposure data, COVID symptoms without lab confirmation) were included in this study.
Respondents were queried regarding workplace exposures, respiratory protection, and extra-occupational activities. Odds ratios for HCP infection were calculated using multivariable logistic regression and sensitivity analyses controlling for confounders and known biases.
HCP infection was associated with non-aerosol-generating contact with COVID-19 patients (adjusted OR, 1.4; 95% CI, 1.04-1.9; P = .03) and extra-occupational exposures including gatherings of ≥10 people, patronizing restaurants or bars, and public transportation (adjusted OR range, 3.1-16.2). Respirator use during aerosol-generating procedures (AGPs) was associated with lower odds of HCP infection (adjusted OR, 0.4; 95% CI, 0.2-0.8, P = .005), as was exposure to intensive care and dedicated COVID units, negative pressure rooms, and personal protective equipment (PPE) observers (adjusted OR range, 0.4-0.7).
COVID-19 transmission to HCP was associated with medical exposures currently considered lower-risk and multiple extra-occupational exposures, and exposures associated with proper use of appropriate PPE were protective. Closer scrutiny of infection control measures surrounding healthcare activities and medical settings considered lower risk, and continued awareness of the risks of public congregation, may reduce the incidence of HCP infection.
PDF
