Robby Vroemans

Nature Chemistry, Published online: 10 June 2021; doi:10.1038/s41557-021-00731-0

All-carbon quaternary centres are challenging targets in organic synthesis. Now, the development of a zinc-catalysed desymmetrization method enables the synthesis of chiral alcohols with all-carbon quaternary centres by the selective reduction of symmetrical α,α-disubstituted malonates.

Synlett
DOI: 10.1055/s-0040-1706042

Reduction-and-oxidation (redox) reactions are one of the most utilized approaches for the synthesis of value-added compounds. With the growing awareness of green chemistry, researchers have searched for new and sustainable pathways for performing redox reactions. From this, a new field has gained tremendous attention, namely photoredox catalysis. Here, molecules can be easily oxidized or reduced with the use of one of Nature’s biggest resources: visible light. This tutorial paper gives the basics of photoredox catalysis along with limited examples to encourage further research in this blooming research area.1 Introduction2 Redox Chemistry3 Photochemistry3.1 Laws of Photochemistry3.2 Principles3.3 Examples4 Photoredox Catalysis4.1 General Principles4.2 Classification of Redox Processes4.3 Other Mechanistic Considerations4.4 Stern–Volmer Plots4.5 Photophysical Properties4.6 Redox Potentials5 Photocatalysts5.1 Metal-Based Photocatalysts5.2 Organic Dyes5.3 Semiconductors6 Dual Catalysis7 Conclusions
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Nature Reviews Chemistry, Published online: 09 June 2021; doi:10.1038/s41570-021-00299-w

An experiment that challenged established dogma opened an entirely new avenue for research in the assembly and control of mechanically interlocked compounds.

Nature Chemistry, Published online: 31 May 2021; doi:10.1038/s41557-021-00716-z

Statistical tools based on machine learning are becoming integrated into chemistry research workflows. We discuss the elements necessary to train reliable, repeatable and reproducible models, and recommend a set of guidelines for machine learning reports.

Progress in enantioselective organocatalysis have enabled efficient and highly stereoselective syntheses of cyclobutane derivatives using (2+2) annulation reactions. Taking advantage of their strain-releasing fragmentation, cyclobutane derivatives, especially cyclobutanones and cyclobutenones, can now be regarded as versatile four-carbon atom units amenable to the enantioselective organocatalyzed construction of five- to eight-membered rings by (4+n) annulation reactions.

Abstract

The progress in enantioselective organocatalysis have enabled efficient and highly stereoselective syntheses of cyclobutane derivatives, through (2+2) annulation reactions, overcoming the geometrical constraints inherent to these small cyclic molecules. More importantly, and taking advantage of their strain-releasing fragmentation, some cyclobutane derivatives, especially cyclobutanones and cyclobutenones, can now be regarded as versatile four-carbon atoms units amenable to the enantioselective construction of larger rings by (4+n) annulation reactions to produce, five-, six-, seven- and eight-membered cyclic products. These recent developments concerning the enantioselective synthetic chemistry of cyclobutane derivatives under organocatalytic conditions are reviewed herein.

Chiral cyclopentadienyls (Cp^X) have emerged as powerful steering ligands in asymmetric catalysis. This Review discusses the existing ligand classes, their design, syntheses, and metalation methods. Details on the successful application of the metal complexes in numerous catalytic processes are provided. Those include C−H bond functionalization chemistry and beyond, enabling access to valuable chiral molecules.

Abstract

The creation of new chiral ligands capable of providing high stereocontrol in metal-catalyzed reactions is crucial in modern organic synthesis. The production of bioactive molecules as single enantiomers is increasingly required, and asymmetric catalysis with metal complexes constitutes one of the most efficient synthetic strategies to access optically active compounds. Herein we offer a historical overview on the development of chiral derivatives of the ubiquitous cyclopentadienyl ligand (Cp^X), and detail their successful application in a broad range of metal-catalyzed transformations. Those include the functionalization of challenging C−H bonds and beyond, giving access to an extensive catalogue of valuable chiral molecules. A critical comparison of the existing ligand families, their design, synthesis, and complexation to different metals is also provided. In addition, future research directions are discussed to further enhance the performance and application of Cp^X ligands in enantioselective catalysis.

Chelating-benzylidene ruthenium complexes (so-called Hoveyda–Grubbs catalysts) activated by electron-withdrawing groups (EWGs) are finding practical applications in target-oriented synthesis, medicinal chemistry, the preparation of fine-chemicals, and in materials chemistry.

Abstract

Advanced applications of the Nobel Prize winning olefin metathesis reaction require user-friendly and highly universal catalysts. From many successful metathesis catalysts, which belong to the two distinct classes of Schrock and Grubbs-type catalysts, the subclass of chelating-benzylidene ruthenium complexes (so-called Hoveyda–Grubbs catalysts) additionally activated by electron-withdrawing groups (EWGs) provides a highly tunable platform. In the Review, the origin of the EWG-activation concept and selected applications of the resulting catalysts in target-oriented synthesis, medicinal chemistry, as well as in the preparation of fine-chemicals and in materials chemistry is discussed. Based on the examples, some suggestions for end-users regarding minimization of catalyst loading, selectivity control, and general optimization of the olefin metathesis reaction are provided.

“3 D” drug development: The deuterated “magic methyl” group is attracting increased interest in pharmaceutical industry. In this review, we discuss the currently available methods for C−CD₃ bond forming reactions and classify them according to the trideuteromethylation reagent. The mechanisms, scope and limitations of each method are considered in order to provide a guide for targeted trideutermethylation.

Abstract

In the field of medicinal chemistry, the precise installation of a trideuteromethyl group is gaining ever-increasing attention. Site-selective incorporation of the deuterated “magic methyl” group can provide profound pharmacological benefits and can be considered an important tool for drug optimization and development. This review provides a structured overview, according to trideuteromethylation reagent, of currently established methods for site-selective trideuteromethylation of carbon atoms. In addition to CD₃, the selective introduction of CD₂H and CDH₂ groups is also considered. For all methods, the corresponding mechanism and scope are discussed whenever reported. As such, this review can be a starting point for synthetic chemists to further advance trideuteromethylation methodologies. At the same time, this review aims to be a guide for medicinal chemists, offering them the available C−CD₃ formation strategies for the preparation of new or modified drugs.

It is an oversight to consider that a Lewis base such as a trialkylamine adds to an activated alkene in conjugate fashion to generate an enolate as a 1,5-zwitterion, which next reacts in aldol fashion with an electrophile such as an aldehyde to move on further through other events to the Morita-Baylis-Hillman product. It is demonstrated from computational investigations that the union of trialkylamine and activated alkene leads possibly to a very low level charge-transfer entity, wherein the p-electron density of the alkene has little perturbed to call it an enolate in the conventional sense. It is suggested to consider the aldol reaction as the first step of the Morita-Baylis-Hillman reaction and arrive at the corresponding transition state structure directly from the three entities.

The frontispiece shows the transformation of Fischer Carbene Complexes in a wide variety of compounds through of Higher-order Cycloadditions. The flask, containing the carbene, pour on the paper the different products synthesized in the last 20 years. In the background, the blackboard draws traces of important contributions in the area, such as the orbital correlation diagrams for Higher-order Cycloadditions and the representation of molecular orbitals made by Woodward and Hoffmann, that established the bases in this research area. For more details see the Review by M. A. Vázquez et al. on 8233 ff.

Nature Communications, Published online: 03 June 2021; doi:10.1038/s41467-021-23326-2

Arene-fused siloles have attracted interest due to their promising applications in electronic and optoelectronic devices. Here, the authors report Ir(III)-catalyzed cycloaromatization of ortho-alkynylaryl vinylsilanes with arylsulfonyl azides via α-silyl radical Smiles rearrangement for accessing naphthyl-fused benzosiloles under visible-light photoredox conditions.

Vancomycin-functionalized porphyrinic metal-organic framework PCN-224 displays the integrated merits of the bacteria-targeting ability of vancomycin and the photodynamic effect of PCN-224 for enhanced targeted sterilization.

Abstract

A vancomycin (Van) modification strategy on a porphyrinic metal-organic framework (MOF) PCN-224 is presented. The obtained Van-PCN-224 gives the combined advantages of porphyrinic MOF and Van with high photosensitive activity and excellent targeted antibacterial activity against Staphylococcus aureus. The features make Van-PCN-224 promising for antimicrobial therapy.

The present review describes the methodologies reported for the synthesis of 1,3-diazepine derivatives. This heterocyclic moiety forms the core structure of many compounds with potent biological activities. Synthetic strategies by ring closure or ring transformation are discussed.

Abstract

The present review describes the methodologies reported for the synthesis of 1,3-diazepine derivatives. This heterocyclic moiety forms the core structure of many compounds with potent biological activities. Synthetic strategies by ring closure or ring transformation are discussed.

Publication date: May–June 2021

Source: Mendeleev Communications, Volume 31, Issue 3

Author(s): Leonid M. Kustov, Andrei L. Tarasov, Vera D. Nissenbaum, Alexander L. Kustov