Synthesis of Diaryl Tellurides with Sodium Aryltellurites under Mild Conditions

A highly efficient new protocol has been developed for the formation of C-Te bonds, leading to both symmetrical and unsymmetrical diaryl tellurides. This protocol utilizes sodium aryltellurites (4), which can be easily prepared from low-cost aryltelluride trichlorides and NaOH. The synthesis involves the use of 4 and arylazo sulfones as starting materials in the presence of (MeO)2P(O)H. A variety of diaryl tellurides are obtained in moderate to good yields using this method. Importantly, this innovative protocol eliminates the need for traditional, highly toxic aryltellurolating reagents such as diaryl ditellurides and elemental tellurium. This study will bring new vitality to the synthesis of tellurides.

Nonbasic Synthesis of Thioethers via Nickel-Catalyzed Reductive Thiolation Utilizing NBS-Like N-Thioimides as Electrophilic Sulfur Donors

The nonbasic synthesis of unsymmetrical thioethers via nickel-catalyzed reductive thiolation between aryl(hetero) iodides and N-thioimides is illustrated. N-Bromosuccinimide (NBS)-like N-thioimides were found quite reactive toward thiolation with carbon electrophiles, and a series of structurally varied thioethers were successfully prepared under mild reaction conditions. The transformation was featured with the new application of the NBS-like reagents, good functional group tolerance, and late-stage modification of biologically active scaffolds, thus providing an expeditious and efficient platform to construct polyfunctional thioethers.

Copper-Promoted Hiyama Cross-Coupling of Arylsilanes With Thiuram Reagents: A Facile Synthesis of Aryl Dithiocarbamates

We report herein a facile Hiyama cross-coupling reaction of arylsilanes with thiuram reagents (tetraalkylthiuram disulfides or tetraalkylthiuram monosulfide) enabled by copper fluoride. Compared to our previous work, this protocol is an alternative protocol for the generation of S-aryl dithiocarbamates. It features low toxic and readily available substrates, cost-effective promoter, easy performance, and provides good yields.

Understanding flow chemistry for the production of active pharmaceutical ingredients

Multi-step organic syntheses of various drugs, active pharmaceutical ingredients, and other pharmaceutically and agriculturally important compounds have already been reported using flow synthesis. Compared to batch, hazardous and reactive reagents can be handled safely in flow. This review discusses the pros and cons of flow chemistry in today’s scenario and recent developments in flow devices. The review majorly emphasizes on the recent developments in the flow synthesis of pharmaceutically important products in last five years including flibanserin, imatinib, buclizine, cinnarizine, cyclizine, meclizine, ribociclib, celecoxib, SC-560 and mavacoxib, efavirenz, fluconazole, melitracen HCl, rasagiline, tamsulosin, valsartan, and hydroxychloroquine. Critical steps and new development in the flow synthesis of selected compounds are also discussed.

Diorganyl diselenides: a powerful tool for the construction of selenium containing scaffolds

Organoselenium compounds find versatile applications in organic synthesis, materials synthesis, and ligand chemistry. Organoselenium heterocycles are widely studied agents with diverse applications in various biological processes. This review highlights the recent progress in the synthesis of selenium heterocycles using diorganyl diselenides with keen attention on green synthetic approaches, scopes, C-H selanylation, the mechanisms of different reactions and insights into the formation of metal complexes. The C-H selanylation using diorganyl diselenides with different catalysts, bases, transition metals, iodine salts, NIS, hypervalent iodine, and other reagents is summarised. Finally, the diverse binding modes of bis(2/4-pyridyl)diselenide with different metal complexes are also summarised.

Ligand-Free Copper(I)-Mediated Cross-Coupling Reactions of Organostannanes with Sulfur Electrophiles

The synthesis of aryl thioether through the cross-coupling of C-S bond is a highly attractive area of research due to the prevalence of aryl thioether in bioactive natural products, functional materials, agrochemicals, and pharmaceutically active compounds. Herein, we report a ligand-free Cu(I) mediated electrophilic thiolation of organostannanes with sulfur electrophiles. A selective transfer of alkyl groups was achieved in reactions with alkyl carbastannatranes affording congested thioethers. This study offers a unified method to access diaryl and aryl alkyl thioethers and was demonstrated in the context of late-stage modifications..

Recent Developments and Perspectives in the C-Se Cross Coupling Reactions

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The C-Se bond forming reactions are attractive synthetic strategies for biochemists and synthetic chemists alike for the synthesis of various molecules that are of biological, pharmaceutical and material interest. Therefore, the design and synthesis of organoselenium compounds currently constitute engaging fundamental problems in applied chemistry both in pharmaceutical and academic laboratories. This review discusses the recent works reported in carbon–selenium cross-coupling reactions with the emphasis on the mechanistic aspects of the reactions. The reacting species, the addition of ligands, selection of catalysts, use of suitable solvents, proper setting of reaction time, are well discussed to understand the detailed mechanism. Various simple, economical and environmentally friendly protocols are demonstrated, which ensured product stability, low toxicity, environmentally benign and excellent reactivity for the synthesis of organoselenium compounds. This review covers the scientific literature from 2010 to 2019.

Ullmann-type C-Se Cross-Coupling in the Hydantoin Family: Synthesis, Mechanistic Studies, and Tests of Biological Activity

An attractive strategy for C-Se bond formation by Ullmann-type copper(I)-promoted cross-coupling is developed. A wide range of aryliodides reacts with various disubstituted 2-selenohydantoins under mild conditions and provides Se-arylated imidazolines in moderate to high yields. Computational mechanistic studies show the oxidative addition/intramolecular reductive elimination likely to be the lowest-energy pathway. Cytotoxic activity of all 43 reaction products has been tested in vitro against MCF7 and A549 cancer cell lines with VA13 and MCF10a control cells.

Palladium-Catalyzed Direct Ortho-C-H Selenylation of Benzaldehydes Using Benzidine as a Transient Directing Group

Benzidine was found to be a novel transient directing group to enable Pd-catalyzed direct selenylation of inert C(sp²)-H bonds of benzaldehydes. Diverse diarylselenides were readily constructed in high efficiency and satisfactory yields with good functional group tolerance. The practical usage of the method was further demonstrated by enlarged reaction to gram scale and application in the facile access to two selenoxanthenes and one fluorescent probe.