LongLarf

Nature Chemistry, Published online: 25 July 2022; doi:10.1038/s41557-022-00996-z

The introduction of fluorine into a drug molecule can alter the biological responses to it, including modulating bioavailability, pharmacokinetics and selectivity. Now, a hybrid polyketide/fatty acid synthase multienzyme has been designed to incorporate fluorinated precursors during polyketide biosynthesis in an approach that provides new chemoenzymatic access to fluorinated natural compounds.

Synlett
DOI: 10.1055/a-1873-3530

A process for the synthesis of P-chiral triarylphosphine sulfides via sequential Pd-catalyzed stereospecific P–C coupling reactions of P-chiral precursors prepared by enzymatic desymmetrization was developed. Three independent aryl substituents could be introduced onto the P atom by the sequential P–C couplings under mild conditions while retaining the high enantiopurity.
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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Article in Thieme eJournals:
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Single atom catalysts consist of a transition metal embedded in a supporting matrix. We show that in determining the final catalytic activity in Hydrogen Evolution (HER) Reaction the transition metal and the neighbouring atoms are equally important and that comparable changes in reactivity can be induced by changing the metal or by replacing the atoms bound to it.

Abstract

Single atom catalysts (SACs) consist of isolated metal atoms stabilized on a solid support. The name suggests that the catalytic activity is due to the nature of the metal atom, but of course the interaction with the substrate plays a role as well. But what is more important? The metal atom or its surrounding? To answer this question, we have performed numerical experiments based on density functional theory (DFT). 24 transition metal atoms have been incorporated in Nitrogen-doped graphene, and the catalytic activity in the hydrogen evolution reaction (HER) has been studied changing the metal and keeping the N-doped graphene matrix fixed. Then, one specific atom, Pt, has been embedded in the same matrix but the nitrogen neighbors of Pt have been systematically replaced by carbon or oxygen atoms generating more than 20 structures. The HER has thus been studied by keeping the metal center fixed but changing the surrounding. It turns out that the same great variability in chemical behavior can be achieved by changing the active site or the surrounding environment. This shows the importance of the local coordination in determining the catalytic activity. The consequences of this conclusion for modeling studies of SACs are discussed.

This work provides the complete reaction pathway and axial ligand effect for heme protein catalyzed intramolecular C−H aminations. Results reproduced experimentally found rate-determining step and axial ligand trend and revealed the electronic driving force information to understand them. New ideas for biocatalyst design in this field were offered.

Abstract

Engineered heme protein biocatalysts provide an efficient and sustainable approach to develop amine-containing compounds through C−H amination. A quantum chemical study to reveal the complete heme catalyzed intramolecular C−H amination pathway and protein axial ligand effect was reported, using reactions of an experimentally used arylsulfonylazide with hemes containing L=none, SH⁻, MeO⁻, and MeOH to simulate no axial ligand, negatively charged Cys and Ser ligands, and a neutral ligand for comparison. Nitrene formation was found as the overall rate-determining step (RDS) and the catalyst with Ser ligand has the best reactivity, consistent with experimental reports. Both RDS and non-RDS (nitrene transfer) transition states follow the barrier trend of MeO⁻<SH⁻<MeOH<None due to the charge donation capability of the axial ligand to influence the key charge transfer process as the electronic driving forces. Results also provide new ideas for future biocatalyst design with enhanced reactivities.

The coordination chemistry of f-block elements in molten salts has become a resounding topic owing to fundamental interests and potential applications in molten salt reactors and pyroprocessing. This concept paper highlights the state-of-the-art in the coordination chemistry of f-block elements in molten salts, which may advance understanding of the nature of molten salt fuels, coolants and electrolytes.

Abstract

The coordination chemistry of f-block elements (lanthanide and actinide) in molten salts has become a resounding topic in view of its great importance to the research and development (R&D) of molten salt reactors and pyroprocessing. In this Review article, a general overview of the coordination chemistry of f-block elements in molten salts is provided including past achievements and recent advances. Particular emphases are placed on the oxidation state, speciation, and solution structure of f-block metal ions in molten salts, as well as their relationships with the salt composition. Furthermore, this review briefly discusses the spectroscopic and theoretical methods that complement each other in revealing the coordination properties.

Synthesis
DOI: 10.1055/a-1868-4148

Vinyl sulfides accessed via Wittig olefination with thioalkylphosphonium salts are used as aldehyde- or ketone surrogates in Fischer indole reactions. These vinyl sulfides react with arylhydrazines in the presence of TsOH·H2O in refluxing ethanol or dichloroethane to yield diverse 3-substituted and 2,3-disubstituted indoles or azaindoles. The utility of this chemistry is highlighted with the efficient preparation of three biomedically relevant compounds: 4-aza-melatonin, a furoindoline, and an indomethacin-like CRTh2 antagonist.
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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Article in Thieme eJournals:
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Nature, Published online: 11 July 2022; doi:10.1038/s41586-022-05000-9

Author Correction: Skeletal editing through direct nitrogen deletion of secondary amines