Resurgence and advancement of photochemical hydrogen atom transfer processes in selective alkane functionalizations

Chemical Science, Journal Year: 2023, Volume and Issue: 14(25), P. 6841 - 6859

Published: Jan. 1, 2023

The selective functionalization of alkanes has long been recognized as a prominent challenge and an arduous task in organic synthesis. Hydrogen atom transfer (HAT) processes enable the direct generation reactive alkyl radicals from feedstock have successfully employed industrial applications such methane chlorination process,

Language: Английский

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Electroreductive Dicarboxylation of Unactivated Skipped Dienes with CO₂

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(23)

Published: April 3, 2023

Carboxylation of easily available alkenes with CO2 is highly important to afford value-added carboxylic acids. Although dicarboxylation activated alkenes, especially 1,3-dienes, has been widely investigated, the challenging unactivated 1,n-dienes (n>3) remains unexplored. Herein, we report first skipped dienes via electrochemistry, affording valuable dicarboxylic Control experiments and DFT calculations support single electron transfer (SET) reduction its radical anion, which followed by sluggish addition SET unstabilized alkyl radicals carbanions nucleophilic attack on give desired products. This reaction features mild conditions, broad substrate scope, facile derivations products promising application in polymer chemistry.

Language: Английский

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Site- and enantioselective cross-coupling of saturated N-heterocycles with carboxylic acids by cooperative Ni/photoredox catalysis

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: Jan. 9, 2023

Abstract Site- and enantioselective cross-coupling of saturated N -heterocycles carboxylic acids—two the most abundant versatile functionalities—to form pharmaceutically relevant α-acylated amine derivatives remains a major challenge in organic synthesis. Here, we report general strategy for highly site- α-acylation with situ-activated acids. This modular approach exploits hydrogen-atom-transfer reactivity photocatalytically generated chlorine radicals combination asymmetric nickel catalysis to selectively functionalize cyclic α-amino C−H bonds presence benzylic, allylic, acyclic α-amino, α-oxy methylene groups. The mild scalable protocol requires no organometallic reagents, displays excellent chemo-, enantioselectivity, is amenable late-stage diversification, including synthesis previously inaccessible Taxol derivatives. Mechanistic studies highlight exceptional versatility chiral catalyst orchestrating (i) catalytic elimination, (ii) alkyl radical capture, (iii) cross-coupling, (iv) induction.

Language: Английский

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The Rational Design of Reducing Organophotoredox Catalysts Unlocks Proton-Coupled Electron-Transfer and Atom Transfer Radical Polymerization Mechanisms

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(3), P. 1835 - 1846

Published: Jan. 6, 2023

Photocatalysis has become a prominent tool in the arsenal of organic chemists to develop and (re)imagine transformations. However, only handful versatile photocatalysts (PCs) are available, hampering discovery new reactivities. Here, we report design complete physicochemical characterization 9-aryl dihydroacridines (9ADA) 12-aryl dihydrobenzoacridines (12ADBA) as strong reducing PCs. Punctual structural variations modulate their molecular orbital distributions unlock locally or charge-transfer (CT) excited states. The PCs presenting state showed better performances photoredox defunctionalization processes (yields up 92%), whereas featuring CT produced promising results atom transfer radical polymerization under visible light (up 1.21 Đ, 98% I*). Unlike all PC classes reported so far, 9ADA 12ADBA feature free NH group that enables catalytic multisite proton-coupled electron (MS-PCET) mechanism. This manifold allows reduction redox-inert substrates including aryl, alkyl halides, azides, phosphate ammonium salts (Ered -2.83 vs SCE) single-photon excitation. We anticipate these will open mechanistic manifolds field photocatalysis by allowing access previously inaccessible intermediates one-photon

Language: Английский

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Single-Electron Oxidation-Initiated Enantioselective Hydrosulfonylation of Olefins Enabled by Photoenzymatic Catalysis

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(4), P. 2748 - 2756

Published: Jan. 12, 2024

Controlling the enantioselectivity of hydrogen atom transfer (HAT) reactions has been a long-standing synthetic challenge. While recent advances on photoenzymatic catalysis have demonstrated great potential non-natural photoenzymes, all transformations are initiated by single-electron reduction substrate, with only one notable exception. Herein, we report an oxidation-initiated enantioselective hydrosulfonylation olefins using novel mutant gluconobacter ene-reductase (GluER-W100F-W342F). Compared to known systems, our approach does not rely formation electron donor–acceptor complex between substrates and enzyme cofactor simplifies reaction system obviating addition regeneration mixture. More importantly, GluER variant exhibits high reactivity broad substrate scope. Mechanistic studies support proposed mechanism reveal that tyrosine-mediated HAT process is involved.

Language: Английский

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Radical Polarity

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

Published: Oct. 3, 2024

The polarity of a radical intermediate profoundly impacts its reactivity and selectivity. To quantify this influence predict effects, the electrophilicity/nucleophilicity >500 radicals has been calculated. This database open-shell species entails frequently encountered synthetic intermediates, including centered at sp

Language: Английский

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Boryl radical-mediated halogen-atom transfer enables arylation of alkyl halides with electrophilic and nucleophilic coupling partners

Nature Synthesis, Journal Year: 2024, Volume and Issue: 3(10), P. 1221 - 1230

Published: July 1, 2024

Language: Английский

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A Radical Strategy for the Alkylation of Amides with Alkyl Halides by Merging Boryl Radical-Mediated Halogen-Atom Transfer and Copper Catalysis

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(32), P. 22424 - 22430

Published: Aug. 1, 2024

Amide alkylation is a fundamental process in organic chemistry. However, the low nucleophilicity of amides means that divergent coupling with alkyl electrophiles often not achievable. To circumvent this reactivity challenge, individual amine synthesis followed by amidation standard agents generally required. Herein, we demonstrate radical solution to challenge using an amine–borane complex and copper catalysis under oxidative conditions. While borohydride reagents are used as reducing ionic chemistry, their conversion into amine-ligated boryl radicals diverts toward halogen-atom transfer. This enables halides corresponding for amide functionalization via catalysis. The applicable N-alkylation primary employing unactivated iodides bromides, it was also showcased late-state both amide- halide-containing drugs.

Language: Английский

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Synergistic catalysis: An emerging concept for selective carbohydrate synthesis

Chem Catalysis, Journal Year: 2024, Volume and Issue: 4(3), P. 100891 - 100891

Published: Jan. 18, 2024

Harnessing modern catalytic concepts to address long-standing challenges in carbohydrate chemistry has garnered substantial interest from the synthetic community recent years. In particular, usage of multiple catalysts for sequential one-pot relay reactions already contributed major benefits accessing oligosaccharides past two decades. contrast, exploitation synergistic catalysis glycosciences is only its infancy. While methods combine stepwise into a single flask operation, they do not intrinsically alter reaction mechanisms. Conversely, involves creation unique mechanistic pathways by merging cycles. At nexus cycles, fertile opportunities arise bond-forming strategies that are possible within individual manifold. The realization underexploited potential expected accelerate developments field, thereby offering stereoselective entry points glycosidic chemical space was previously inaccessible.

Language: Английский

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Site-selective arene C–H amination with iron-aminyl radical

Nature Catalysis, Journal Year: 2024, Volume and Issue: 7(6), P. 636 - 645

Published: April 1, 2024

Language: Английский

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