Co-Catalyzed Hydrofluorination of Alkenes: Photocatalytic Method Development and Electroanalytical Mechanistic Investigation

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(7), С. 4380 - 4392

Опубликована: Фев. 1, 2024

The hydrofluorination of alkenes represents an attractive strategy for the synthesis aliphatic fluorides. This approach provides a direct means to form C(sp3)–F bonds selectively from readily available alkenes. Nonetheless, conducting using nucleophilic fluorine sources poses significant challenges due low acidity and high toxicity associated with HF poor nucleophilicity fluoride. In this study, we present new Co(salen)-catalyzed simple utilizing Et3N·3HF as sole source both hydrogen fluorine. process operates via photoredox-mediated polar-radical-polar crossover mechanism. We also demonstrated versatility method by effectively converting diverse array activated varying degrees substitution into hydrofluorinated products. Furthermore, successfully applied methodology 18F-hydrofluorination reactions, enabling introduction 18F potential radiopharmaceuticals. Our mechanistic investigations, conducted rotating disk electrode voltammetry DFT calculations, unveiled involvement carbocation CoIV–alkyl species viable intermediates during fluorination step, contribution each pathway depends on structure starting alkene.

Язык: Английский

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Mechanism of Alkene Hydrofunctionalization by Oxidative Cobalt(salen) Catalyzed Hydrogen Atom Transfer

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(4), С. 2685 - 2700

Опубликована: Янв. 16, 2024

Oxidative MHAT hydrofunctionalization of alkenes provides a mild cobalt-catalyzed route to forming C–N and C–O bonds. Here, we characterize relevant salen-supported cobalt complexes their reactions with alkenes, silanes, oxidant, solvent. These stoichiometric investigations are complemented by kinetic studies the catalytic reaction catalyst speciation. We describe solution characterization an elusive cobalt(III) fluoride complex, which surprisingly is not species that reacts silane under conditions; rather, aquo complex more active. Accordingly, addition water (0.15 M) speeds reaction, show enables product formation in 2 h at −50 °C acetone. Under these conditions, resting states can be observed UV–vis spectrophotometry, including cobalt(III)-alkyl complex. It comes from transient hydride formed turnover-limiting step cycle. This readily degrades but H2; it releases H+ through bimetallic pathway explains [Co]2 dependence off-cycle reaction. In contrast, rate follows power law kobs[Co]1[silane]1. Because different [Co] degradation lower loading improves yield reducing relative unproductive silane/oxidant consumption. illuminate mechanistic details oxidative lay groundwork for understanding other mediated alkyl complexes.

Язык: Английский

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Electrochemical Nickel‐Catalyzed Hydrogenation

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(22)

Опубликована: Март 20, 2024

Olefin hydrogenation is one of the most important transformations in organic synthesis. Electrochemical transition metal-catalyzed an attractive approach to replace dangerous hydrogen gas with electrons and protons. However, this reaction poses major challenges due rapid evolution (HER) metal-hydride species that outcompetes alkene step, facile deposition metal catalyst at electrode stalls reaction. Here we report economical efficient strategy achieve high selectivity for reactivity over well-established HER. Using inexpensive bench-stable nickel salt as catalyst, mild features outstanding substrate generality functional group compatibility, distinct chemoselectivity. In addition, hydrodebromination alkyl aryl bromides could be realized using same system a different ligand, chemoselectivity between achieved through ligand selection. The practicability our method has been demonstrated by success large-scale synthesis catalytic amount electrolyte minimal solvent. Cyclic voltammetry kinetic studies were performed, which support Ni

Язык: Английский

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Closed-Loop Navigation of a Kinetic Zone Diagram for Redox-Mediated Electrocatalysis Using Bayesian Optimization, a Digital Twin, and Automated Electrochemistry

Analytical Chemistry, Год журнала: 2025, Номер unknown

Опубликована: Март 7, 2025

Molecular electrocatalysis campaigns often require tuning multiple experimental parameters to obtain kinetically insightful electrochemical measurements, a prohibitively time-consuming task when performing comprehensive studies across catalysts and substrates. In this work, we present an autonomous workflow that combines Bayesian optimization automated electrochemistry perform fully unsupervised cyclic voltammetry (CV) of molecular electrocatalysis. We developed CV descriptors leveraged the conceptual framework EC' (where denotes step followed by catalytic chemical step) kinetic zone diagram enable efficient optimization. The descriptor's effect on performance was evaluated using digital twin our platform, quantifying accuracy obtained values against known ground truth. demonstrated platform experimentally TEMPO-catalyzed ethanol isopropanol electro-oxidation, demonstrating rapid identification conditions in 10 or less iterations through closed-loop workflow. Overall, work highlights application platforms accelerate mechanistic beyond.

Язык: Английский

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Electrohydrogenation of Nitriles with Amines by Cobalt Catalysis

Angewandte Chemie International Edition, Год журнала: 2023, Номер 63(7)

Опубликована: Дек. 21, 2023

Abstract Catalytic hydrogenation of nitriles represents an efficient and sustainable one‐step synthesis valuable bulk fine chemicals. We report herein a molecular cobalt electrocatalyst for selective hydrogenative coupling with amines using protons as the hydrogen source. The key to success this reductive reaction is use electrocatalytic approach cobalt‐hydride generation through sequence cathodic reduction protonation. As only electrons (e − ) (H + redox equivalent source, general electrohydrogenation protocol showcased by highly straightforward various functionalized structurally diverse amines, well deuterium isotope labeling applications. Mechanistic studies reveal that electrogenerated transfer nitrile process rate‐determining step.

Язык: Английский

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Advanced Electroanalysis for Electrosynthesis

ACS Organic & Inorganic Au, Год журнала: 2023, Номер 4(2), С. 141 - 187

Опубликована: Ноя. 29, 2023

Electrosynthesis is a popular, environmentally friendly substitute for conventional organic methods. It involves using charge transfer to stimulate chemical reactions through the application of potential or current between two electrodes. In addition electrode materials and type reactor employed, strategies controlling have an impact on yields, product distribution, reaction mechanism. this Review, recent advances related electroanalysis applied in electrosynthesis were discussed. The first part study acts as guide that emphasizes foundations electrosynthesis. These essentials include instrumentation, selection, cell design, methodologies. Then, electroanalytical techniques organic, enzymatic, microbial are illustrated with specific cases studied literature. To conclude, discussion future possibilities intend advance academic industrial areas presented.

Язык: Английский

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An automated electrochemistry platform for studying pH-dependent molecular electrocatalysis

Digital Discovery, Год журнала: 2024, Номер 3(9), С. 1812 - 1821

Опубликована: Янв. 1, 2024

An automated electrochemistry platform designed for molecular electrocatalysis studies.

Язык: Английский

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Cobalt-catalyzed radical hydroamination of olefins

Trends in Chemistry, Год журнала: 2025, Номер unknown

Опубликована: Фев. 1, 2025

Язык: Английский

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Modifying commodity-relevant unsaturated polymers via Co-catalyzed MHAT

Chem, Год журнала: 2024, Номер 10(10), С. 3088 - 3099

Опубликована: Июнь 19, 2024

Язык: Английский

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Electrochemical Nickel‐Catalyzed Hydrogenation

Angewandte Chemie, Год журнала: 2024, Номер 136(22)

Опубликована: Март 20, 2024

Abstract Olefin hydrogenation is one of the most important transformations in organic synthesis. Electrochemical transition metal‐catalyzed an attractive approach to replace dangerous hydrogen gas with electrons and protons. However, this reaction poses major challenges due rapid evolution (HER) metal‐hydride species that outcompetes alkene step, facile deposition metal catalyst at electrode stalls reaction. Here we report economical efficient strategy achieve high selectivity for reactivity over well‐established HER. Using inexpensive bench‐stable nickel salt as catalyst, mild features outstanding substrate generality functional group compatibility, distinct chemoselectivity. In addition, hydrodebromination alkyl aryl bromides could be realized using same system a different ligand, chemoselectivity between achieved through ligand selection. The practicability our method has been demonstrated by success large‐scale synthesis catalytic amount electrolyte minimal solvent. Cyclic voltammetry kinetic studies were performed, which support Ni II/0 cycle pre‐coordination center.

Язык: Английский

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