Visible Light-Promoted Deracemization of α-Amino Aldehyde by Synergistic Chiral Primary Amine and Hypervalent Iodine Catalysis

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

Published: Feb. 6, 2025

α-Amino aldehydes, as versatile chiral synthons, are easily racemized under normal acid or base conditions, seriously limiting their synthetic potentials. We report herein an effective deracemization of α-amino aldehydes by a synergistic primary amine and hypervalent iodine catalysis visible light. The developed catalytic system allows for the on-demand production α-Boc- Cbz-protected amino with high enantioselectivity. Mechanistic studies verified photochemical Z-E isomerization mechanism that drives process.

Language: Английский

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Excited-State Palladium-Catalyzed Radical Allylic Alkylation: Rapid Access to C2-Allyl Carbohydrates

ACS Catalysis, Journal Year: 2025, Volume and Issue: unknown, P. 5480 - 5489

Published: March 19, 2025

Language: Английский

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Deracemization of C(sp³)–H Arylated Carbonyl Compounds via Asymmetric Ion-Pairing Photoredox Catalysis

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

Published: April 17, 2025

Deracemization of C(sp3)-H arylated carbonyl compounds faces limitations in terms substrate scope. Through the photoactivation aryl group and stereocontrol generated arene radical cation via asymmetric ion-pairing catalysis, we are able to achieve deracemization at both enolizable unenolizable stereocenters. A diverse range α-, β-, γ-aryl ketones esters, including natural products medicinal derivatives, can be effectively converted into their enantiomers with high enantioselectivity. Mechanistic investigations through combined experimental computational studies suggest that reaction involves single-electron oxidation electron-rich groups, followed by a kinetic resolution resulting intermediates chiral phosphate anion. Deprotonation is identified as stereodetermining step, while stereoselective back electron transfer triplet-state quenching 3 Mes-Acr1+* may also affect enantioselectivity photostationary state.

Language: Английский

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Photocatalyst-Dependent Enantioselectivity in the Light-Driven Deracemization of Cyclic α-Aryl Ketones

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

Published: April 22, 2025

We report a photoredox-enabled deracemization of cyclic α-aryl ketones that occurs with high stereoselectivity and yield proceeds by mechanistically distinct proton transfer reactions. This reaction is jointly mediated visible-light photocatalyst chiral phosphate base cocatalyst under blue light irradiation. Notably, the extent for this exhibits an unexpected dependence on identity concentration cocatalyst, wherein can be increased employing photocatalysts more positive ground-state reduction potentials, raising or combination these factors. effect attributed to two competing processes, back-electron deprotonation, which consume same intermediate, we propose kinetic model rationalizes behavior. also demonstrate redox properties impact product-forming step, dominant stereoselective step in transformation. Together, mechanistic insights facilitate deeper understanding complexity light-driven reactions involving reversible electron suggest approaches processes may increased.

Language: Английский

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Visible Light-Driven Construction of Axially Chiral Heterocyclic Compounds

Topics in heterocyclic chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

Language: Английский

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Photochemical Deracemization of Lactams with Deuteration Enabled by Dual Hydrogen Atom Transfer

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 18, 2024

Photochemical deracemization has emerged as one of the most straightforward approaches to access highly enantioenriched compounds in recent years. While excited-state events such energy transfer, single electron and ligand-to-metal charge transfer have been leveraged promote stereoablation, relying on hydrogen atom which circumvent limitations imposed by triplet redox potential racemic substrates, remain underexplored. Conceptually, attractive method for tertiary stereocenter might be abstraction followed donation. However, implementing a strategy poses significant challenges, primarily because products are also reactive if chiral catalyst is unable differentiate between two enantiomers. Herein we report distinct dual photochemical δ- γ-lactams, achieving high enantioenrichment deuterium incorporation despite inherent reactivity products. Mechanistic studies reveal that benzophenone enables nonselective while tetrapeptide-derived thiol dictates enantioselectivity donation step. More importantly, pyridine-based alcohol was found play crucial roles facilitating well enhancing

Language: Английский

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Enantio- and Regioselective Ni-Catalyzed Radical Relay 1,4-Arylalkylation of 1,3-Enynes to Access Chiral Tetrasubstituted Allenes

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(18), P. 13940 - 13946

Published: Sept. 5, 2024

Language: Английский

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Photoinduced Enantioselective Triplet Radical Reaction on Metal: Copper‐Catalyzed Conjugate Addition of Acylsilanes to α,β‐Unsaturated Ketones and Aldehydes

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(65)

Published: Sept. 16, 2024

Abstract A photoinduced copper‐catalyzed enantioselective conjugate addition of acylsilanes has been developed. The acylation α,β‐unsaturated ketones and aldehydes was promoted by a copper(I)/chiral NHC catalyst under visible‐light irradiation for synthesizing various 2‐substituted 1,4‐dicarbonyl compounds in enantioenriched forms. Mechanistic studies combining experiments quantum chemical calculations indicated reaction mechanism involving copper‐to‐acyl charge transfer (i. e., metal‐to‐ligand (MLCT)) excitation an alkene‐bound acylcopper complex. MLCT is followed electronical geometrical change to generate triplet β‐radical‐ C ‐enolate‐Cu(II)‐acyl complex with acyl radical character, which undergoes facile excited state C−C bond formation the copper coordination sphere, affording 1,4‐conjugate product.

Language: Английский

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Photoexcited Palladium-Catalyzed Synthesis of Chiral Allenes from Alkynes via Isomerization and Deracemization Sequence

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(21), P. 15997 - 16002

Published: Oct. 16, 2024

A photoexcited palladium-catalyzed synthesis of chiral allenes from alkynes via a sequence isomerization and deracemization is disclosed. This method offers an efficient cost-effective approach to produce wide range with good enantioselectivities yields (up 98% yield 99% ee). The use readily available stable as starting materials simplifies experimental procedures broadens the scope allene synthesis. DBU plays crucial dual role in this reaction effectively facilitate enhance under visible light excitation, both which are vital for success process.

Language: Английский

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Enantioselective Propargylic C(sp³)–H Acyloxylation Enabled by Photoexcited Copper Catalysis

Organic Letters, Journal Year: 2024, Volume and Issue: 26(46), P. 10036 - 10040

Published: Nov. 8, 2024

Direct C-H bond functionalization is an efficient method for modifying organic molecules. However, achieving high enantioselectivity and regioselectivity in asymmetric functionalization, particularly of C(sp

Language: Английский

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