Synthesis, antioxidant properties, biological activity and molecular modelling of a series of chalcogen analogues of the 5-lipoxygenase inhibitor DuP 654

Oxidative dual C–H selenation of imidazoheterocycles with ethers or alkanes using selenium powder via a radical pathway

A DCP-mediated oxidative dual C–H selenation radical reaction of imidazoheterocycles with ethers or alkanes using selenium powder was developed.

Copper-catalyzed direct and odorless selenylation with a sodium selenite-based reagent

Use of a new odorless, shelf-stable, easy to handle, practical and scalable direct selenylation reagent, NaO₂SeR, has been disclosed.

Transition Metal- and Oxidant-Free Base-Mediated Selenation of Bicyclic Arenes at Room Temperature

Bicyclic arenyl selenides are of much importance because of their pharmaceutical applications. A simple method for their synthesis has been developed by a reaction of 2-naphthol and styrenyl selenocyanate/diaryl diselenide in the presence of a base at room temperature. The selenation occurs exclusively at the 1-position of 2-naphthol unit. The reactions are relatively fast (2-4 h) and high yielding. A library of substituted naphthyl styrenyl and naphthyl aryl selenides are obtained by this procedure.

Diels-Alder and Stille Coupling Approach for the Short Protecting-Group-Free Synthesis of Mycophenolic Acid, Its Phenylsulfenyl and Phenylselenyl Analogues, and Reactive Oxygen Species (ROS) Probing Capacity in Water

A short, protecting-group-free synthesis is achieved. The synthesis is step-efficient and general. A Diels-Alder and Stille cross-coupling approach includes key transformations, allowing for a competitive synthesis which involves a rare halophenol Stille cross-coupling study. The phenylselenyl and phenylsulfenyl analogues were prepared as novel compounds in good overall yield. The applicability of one of the intermediates as a potential probe for reactive oxygen species (ROS) in water is investigated.

Novel functionalized organotellurides with enhanced thiol peroxidase catalytic activity

Novel tellurium-containing small molecules exhibited remarkable GPx-like activity. Their catalytic properties are strongly influenced by the nature of the β-substituent.

Atom-economical selenation of electron-rich arenes and phosphonates with molecular oxygen at room temperature

An environmentally benign selenation of electron-rich arenes and phosphonates is developed adopting a novel recycle–reuse–reduce strategy for selenol by oxygen.

Rose Bengal catalysed photo-induced selenylation of indoles, imidazoles and arenes: a metal free approach

A photo-induced, metal-free strategy was used for the direct C(sp²)–H bond selenylation of indoles, imidazoles and arenes using Rose Bengal as a photocatalyst.

Organoselenium compounds as mimics of selenoproteins and thiol modifier agents

Selenium is an essential trace element for animals and its role in the chemistry of life relies on a unique functional group: the selenol (-SeH) group. The selenol group participates in critical redox reactions. The antioxidant enzymes glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) exemplify important selenoproteins. The selenol group shares several chemical properties with the thiol group (-SH), but it is much more reactive than the sulfur analogue. The substitution of S by Se has been exploited in organic synthesis for a long time, but in the last 4 decades the re-discovery of ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one) and the demonstration that it has antioxidant and therapeutic properties has renovated interest in the field. The ability of ebselen to mimic the reaction catalyzed by GPx has been viewed as the most important molecular mechanism of action of this class of compound. The term GPx-like or thiol peroxidase-like reaction was previously coined in the field and it is now accepted as the most important chemical attribute of organoselenium compounds. Here, we will critically review the literature on the capacity of organoselenium compounds to mimic selenoproteins (particularly GPx) and discuss some of the bottlenecks in the field. Although the GPx-like activity of organoselenium compounds contributes to their pharmacological effects, the superestimation of the GPx-like activity has to be questioned. The ability of these compounds to oxidize the thiol groups of proteins (the thiol modifier effects of organoselenium compounds) and to spare selenoproteins from inactivation by soft-electrophiles (MeHg⁺, Hg²⁺, Cd²⁺, etc.) might be more relevant for the explanation of their pharmacological effects than their GPx-like activity. In our view, the exploitation of the thiol modifier properties of organoselenium compounds can be harnessed more rationally than the use of low mass molecular structures to mimic the activity of high mass macromolecules that have been shaped by millions to billions of years of evolution.

Calcium mediated C–F bond substitution in fluoroarenes towards C–chalcogen bond formation

An efficient C–F bond substitution in electron-deficient fluoroarenes by chalcogens has been achieved using calcium chloride.

“Pnicogen bonds” or “chalcogen bonds”: exploiting the effect of substitution on the formation of P⋯Se noncovalent bonds

A direct comparison of pnicogen bonds and chalcogen bonds in P⋯Se non-covalent interactions.

Cu(ii) anchored nitrogen-rich covalent imine network (CuII-CIN-1): an efficient and recyclable heterogeneous catalyst for the synthesis of organoselenides from aryl boronic acids in a green solvent

A Cu(ii)-grafted covalent imine framework material has been designed, which catalyzes the C–Se cross-coupling reactions to obtain a library of organoselenides.

5-Selenization of salicylic acid derivatives yielded isoform-specific 5-lipoxygenase inhibitors

Low molecular weight seleno-organic compounds exhibit glutathione peroxidase (GPx)-like activity; the well-known compound ebselen is being used in clinical trials as a stroke medication. Here, we describe the facile one-step synthesis of novel 5-selenized salicylic acid derivatives using selenium tetrachloride. The products were analyzed by spectroscopic studies including (77)Se-NMR and some were subjected to X-ray structure determination. Several products were identified as selective inhibitors of the pro-inflammatory 5-lipoxygenase (LOX) but had little effect on the catalytic activity of 12/15-LOX, which has been implicated in the synthesis of anti-inflammatory mediators. Such isoform-specificity (specificity coefficient >120) has not been reported before for any seleno-organic compound. In addition, synthesis products exhibited GPx-like activity, which was higher than that of ebselen for some derivatives.