Mechanistic Interrogation of Photochemical Nickel-Catalyzed Tetrahydrofuran Arylation Leveraging Enantioinduction Data DOI

Brennan D. McManus,

Lang Hung,

Olivia R. Taylor

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(46), P. 32135 - 32146

Published: Nov. 11, 2024

This manuscript details the development of an asymmetric variant for Ni-photoredox α-arylation tetrahydrofuran (THF), which was originally reported in a racemic fashion by Doyle and Molander. Leveraging enantioselectivity data that we obtained, complex mechanistic scenario different from those proposed is uncovered. Specifically, unexpected dependence product enantiomeric ratio observed on both halide identity (aryl chloride vs bromide substrates) Ni source. Stoichiometric experiments time course analyses evolution with revealed initial behavior reactions carried out Ni(II) Ni(0) precatalysts later converge into common mechanism. For studying predominant pathway, this paper describes rare example syntheses chiral bisoxazoline aryl complexes, proved essential probing via stochiometric experiments. These identify as primary species involved key THF radical trapping event. A multivariate linear regression model presented further validates dominant mechanism delineates structure-selectivity relationships between ligand properties enantioselectivity. EPR analysis Ni(0)/aryl mixtures highlights fast access to variety complexes 0, +1, +2 oxidation states are be responsible divergence when using precatalysts. More broadly, beyond advancing understanding arylation protocol, work underscores potential leveraging unravel intricate manifolds within catalysis.

Language: Английский

From photons to reactions: key concepts in photoredox catalysis DOI

Simon De Kreijger,

Felix Glaser, Ludovic Troian‐Gautier

et al.

Chem Catalysis, Journal Year: 2024, Volume and Issue: unknown, P. 101110 - 101110

Published: Sept. 1, 2024

Language: Английский

Citations

5
Evidence for a Unifying NiI/NiIII Mechanism in Light-Mediated Cross-Coupling Catalysis DOI Creative Commons
Lucia Anghileri, Haralds Baunis,

Aleksander R. Bena

et al.

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: April 11, 2025

Advances in nickel catalysis have significantly broadened the synthetic chemists' toolbox, particularly through methodologies leveraging paramagnetic species via photoredox or electrochemistry. Key to these reactions is oxidation state modulation of single-electron transfer events. Recent mechanistic studies indicate that C(sp2)-heteroatom bond formations proceed NiI/NiIII cycles. Related C(sp2)-C(sp3) cross-couplings operate photocatalytic generation C-centered radicals and a catalytic cycle involves Ni0, NiI, NiIII species. Here, we show light-mediated nickel-catalyzed can be carried out without using exogenous catalysts but with photoactive ligand. In pursuit expanding scope couplings donor-acceptor ligands, identified complex capable catalyzing between aryl halides benzyltrifluoroborate salts. Mechanistic investigations provide evidence transmetalation photochemically generated NiI organoboron compound key step under conditions.

Language: Английский

Citations

0
Unraveling a Complex Mechanistic Picture of Photochemical Nickel-Catalyzed THF Arylation through Product Enantioselectivity Analysis DOI
Ana Bahamonde,

Lang Hung,

Brennan D. McManus

et al.

Synlett, Journal Year: 2025, Volume and Issue: unknown

Published: May 6, 2025

Abstract This study provides a comprehensive mechanistic understanding of asymmetric THF α-O-arylation via Ni photochemical catalysis, leveraging enantioinduction data to refine the reaction pathway. Originally reported in racemic fashion by Molander and Doyle, this transformation was re-examined using chiral bis(oxazoline) ligands, revealing distinct enantioselectivity trends depending on halogen present aryl halide pre-catalyst. Stoichiometric experiments demonstrated that Ni(II) oxidative addition complex is primarily responsible for trapping radical, while multivariate linear regression modeling confirmed remains coordinated during enantiodetermining step. Time-course uncovered an alternative initial pathway when Ni(0) used as pre-catalyst, which ultimately converged main EPR analysis further revealed rapid comproportionation between Ni(II), forming Ni(I) species engage radical at early stages, accounting observed reactivity differences. By integrating with experimental techniques such spectroscopy, establishes powerful tool investigations catalysis. The insights gained not only our transformation, but also provide framework probing similar Ni/Ir dual photocatalytic systems. 1 Introduction 2 Enantioselectivity Data Highlights Complex Mechanistic Scenario 3 Probing Predominant Pathway Experiments 4 MLR Modeling Understand Halogen Effect Enantioinduction 5 Proposed Prevalent Mechanism 6 Initiation Precatalyst 7 Conclusion

Language: Английский

Citations

0
Mechanometallaphotoredox Catalysis: Utilizing Increased Throughput Mechanochemistry to Develop Solvent-Minimized Aryl Amination and C(sp2)-C(sp3) Cross-Coupling Reactions with Increased Tolerance to Aerobic Conditions DOI Creative Commons
Francis Millward, Eli Zysman‐Colman

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: May 22, 2025

Photocatalysis as a tool used in organic synthesis has predominantly relied on the use of solvents, be it under homogeneous or heterogeneous conditions. In particular, metallaphotoredox catalysis reactions commonly toxic solvents such DMA and DMF. Herein, we demonstrate how mechanophotocatalysis, synergistic union mechanochemistry photocatalysis, is compatible with this class dual involving both photocatalyst nickel(II) cocatalysts. Using ball milling, these mechanistically complex can conducted absence bulk solvent air, affording high-yielding aryl aminations C(sp2)-C(sp3) cross-couplings alkyl carboxylic acids, trifluoroborate salts, bromides. These advances are facilitated by introduction novel reaction vessel design for conducting four mechanophotocatalysis simultaneously. This work highlights promise solvent-minimized photocatalysis reactions, demonstrating that examples redundant, thus significantly reducing waste stream. Through time-resolved photoluminescence studies, observed excited states five different photocatalysts were quenched oxygen more solution than solid state, providing evidence origin increased tolerance to aerobic conditions experience.

Language: Английский

Citations

0
Mechanistic Interrogation of Photochemical Nickel-Catalyzed Tetrahydrofuran Arylation Leveraging Enantioinduction Data DOI

Brennan D. McManus,

Lang Hung,

Olivia R. Taylor

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(46), P. 32135 - 32146

Published: Nov. 11, 2024

This manuscript details the development of an asymmetric variant for Ni-photoredox α-arylation tetrahydrofuran (THF), which was originally reported in a racemic fashion by Doyle and Molander. Leveraging enantioselectivity data that we obtained, complex mechanistic scenario different from those proposed is uncovered. Specifically, unexpected dependence product enantiomeric ratio observed on both halide identity (aryl chloride vs bromide substrates) Ni source. Stoichiometric experiments time course analyses evolution with revealed initial behavior reactions carried out Ni(II) Ni(0) precatalysts later converge into common mechanism. For studying predominant pathway, this paper describes rare example syntheses chiral bisoxazoline aryl complexes, proved essential probing via stochiometric experiments. These identify as primary species involved key THF radical trapping event. A multivariate linear regression model presented further validates dominant mechanism delineates structure-selectivity relationships between ligand properties enantioselectivity. EPR analysis Ni(0)/aryl mixtures highlights fast access to variety complexes 0, +1, +2 oxidation states are be responsible divergence when using precatalysts. More broadly, beyond advancing understanding arylation protocol, work underscores potential leveraging unravel intricate manifolds within catalysis.

Language: Английский

Citations

2