Iron-Catalyzed C(Sp³)–H Borylation, Thiolation, and Sulfinylation Enabled by Photoinduced Ligand-to-Metal Charge Transfer

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(13), P. 7600 - 7611

Published: March 23, 2023

Catalytic C(sp3)-H functionalization has provided enormous opportunities to construct organic molecules, facilitating the derivatization of complex pharmaceutical compounds. Within this framework, direct hydrogen atom transfer (HAT) photocatalysis becomes an appealing approach goal. However, viable substrates utilized in these protocols are limited, and site selectivity shows preference activated thermodynamically favored bonds. Herein, we describe development undirected iron-catalyzed borylation, thiolation, sulfinylation reactions enabled by photoinduced ligand-to-metal charge (LMCT) process. These exhibit remarkably broad substrate scope (>150 examples total), most importantly, all three show unconventional regioselectivity, with occurrence preferentially at distal methyl position. The procedures operationally simple readily scalable provide access high-value products from hydrocarbons one step. Mechanistic studies control experiments indicate that afforded is not only relevant HAT species but also largely affected use boron- sulfone-based radical acceptors.

Language: Английский

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Synthetic Application of Bismuth LMCT Photocatalysis in Radical Coupling Reactions

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(2), P. 1125 - 1132

Published: Jan. 9, 2023

Ligand-to-metal charge transfer (LMCT) photocatalysis allows the activation and synthetic utilization of halides other heteroatoms in metal complexes. Many metals are known to undergo LMCT but so far remain underutilized field catalysis. A screening assay identifying activity helped us expand this catalysis concept application bismuth organic radical coupling reactions. We demonstrate its for generation two different radicals (chlorine carboxyl) net-oxidative as well redox-neutral photochemical Detailed investigation model Giese-type revealed BiCl4– BiCl52– catalytically active species under 385 nm irradiation. Combined cyclic voltammetry UV–vis studies gave insight into reactivity highly reactive bismuth(II) catalyst fragment.

Language: Английский

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Terminal C(sp ³ )–H borylation through intermolecular radical sampling

Science, Journal Year: 2024, Volume and Issue: 383(6682), P. 537 - 544

Published: Feb. 1, 2024

Hydrogen atom transfer (HAT) processes can overcome the strong bond dissociation energies (BDEs) of inert C(sp

Language: Английский

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Recent advances in oxidative degradation of plastics

Chemical Society Reviews, Journal Year: 2024, Volume and Issue: 53(14), P. 7309 - 7327

Published: Jan. 1, 2024

Oxidative degradation is a powerful method to degrade plastics into oligomers and small oxidized products. While thermal energy has been conventionally employed as an external stimulus, recent advances in photochemistry have enabled photocatalytic oxidative of polymers under mild conditions. This tutorial review presents overview degradation, from its earliest examples emerging strategies. briefly discusses the motivation development with focus on underlying mechanisms. Then, we will examine modern studies primarily relevant catalytic degradation. Lastly, highlight some unique using unconventional approaches for polymer such electrochemistry.

Language: Английский

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Mechanism of Ni-Catalyzed Photochemical Halogen Atom-Mediated C(sp³)–H Arylation

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(22), P. 15331 - 15344

Published: May 23, 2024

Within the context of Ni photoredox catalysis, halogen atom photoelimination from has emerged as a fruitful strategy for enabling hydrogen transfer (HAT)-mediated C(sp3)–H functionalization. Despite numerous synthetic transformations invoking this paradigm, unified mechanistic hypothesis that is consistent with experimental findings on catalytic systems and accounts radical formation facile C(sp2)–C(sp3) bond remains elusive. We employ kinetic analysis, organometallic synthesis, computational investigations to decipher mechanism prototypical Ni-catalyzed photochemical arylation reaction. Our revise previous proposals, first by examining relevance SET EnT processes intermediates relevant HAT-based investigation highlights ability blue light promote efficient Ni–C(sp2) homolysis cationic NiIII reductive elimination bipyridine NiII complexes. However interesting, rates selectivities these do not account productive pathway. Instead, our studies support involves evolution in situ generated dihalide intermediates, capture NiII(aryl)(halide) resting state, key C–C NiIII. Oxidative addition NiI, opposed Ni0, rapid NiIII/NiI comproportionation play roles process. The presented herein offer fundamental insight into reactivity broader catalysis.

Language: Английский

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Catalysis in the Excited State: Bringing Innate Transition Metal Photochemistry into Play

ACS Catalysis, Journal Year: 2025, Volume and Issue: unknown, P. 4665 - 4680

Published: March 5, 2025

Transition metal catalysis is an indispensable tool for organic synthesis that has been harnessed, modulated, and perfected many decades by careful selection of centers ligands, giving rise to synthetic methods with unparalleled efficiency chemoselectivity. Recent developments have demonstrated how light irradiation can also be recruited as a powerful dramatically alter the outcome catalytic reactions, providing access innovative pathways remarkable potential. In this context, adoption photochemical conditions mainstream strategy drive reactions unveiled exciting opportunities exploit rich excited-state framework transition metals applications. This Perspective examines advances in application complexes standalone photocatalysts, exploiting innate reactivity their excited states beyond common use photoredox catalysts. An account relevant examples dissected provide discussion on electronic reorganization, orbitals involved, associated different types states. analysis aims practitioners fundamental principles guiding strategies understand, design, apply light-activation homogeneous synthesis.

Language: Английский

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The Merger of Benzophenone HAT Photocatalysis and Silyl Radical-Induced XAT Enables Both Nickel-Catalyzed Cross-Electrophile Coupling and 1,2-Dicarbofunctionalization of Olefins

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(18), P. 11216 - 11225

Published: Sept. 1, 2022

A strategy for both cross-electrophile coupling and 1,2-dicarbofunctionalization of olefins has been developed. Carbon-centered radicals are generated from alkyl bromides by merging benzophenone hydrogen atom transfer (HAT) photocatalysis silyl radical-induced halogen (XAT) subsequently intercepted a nickel catalyst to forge the targeted C(sp3)-C(sp2) C(sp3)-C(sp3) bonds. The mild protocol is fast scalable using flow technology, displays broad functional group tolerance, amenable wide variety medicinally relevant moieties. Mechanistic investigations reveal that ketone catalyst, upon photoexcitation, responsible direct activation silicon-based XAT reagent (HAT-mediated XAT) furnishes radical ultimately involved in turnover catalytic cycle.

Language: Английский

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Photoinduced Halogen-Atom Transfer by N-Heterocyclic Carbene-Ligated Boryl Radicals for C(sp³)–C(sp³) Bond Formation

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 145(2), P. 991 - 999

Published: Dec. 30, 2022

Herein, we present a comprehensive study on the use of N-heterocyclic carbene (NHC)-ligated boryl radicals to enable C(sp3)–C(sp3) bond formation under visible-light irradiation via Halogen-Atom Transfer (XAT). The methodology relies an acridinium dye generate boron-centered from corresponding NHC-ligated boranes single-electron transfer (SET) and deprotonation. These subsequently engage with alkyl halides in XAT step, delivering desired nucleophilic radicals. strategy is very mild accommodates broad scope halides, including medicinally relevant compounds biologically active molecules. key role operative reaction mechanism has been elucidated through combination experimental, spectroscopic, computational studies. This stands as significant advancement chemistry radicals, which had long restricted radical reductions, enabling C–C photoredox conditions.

Language: Английский

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Membrane-based TBADT recovery as a strategy to increase the sustainability of continuous-flow photocatalytic HAT transformations

Nature Communications, Journal Year: 2022, Volume and Issue: 13(1)

Published: Oct. 18, 2022

Photocatalytic hydrogen atom transfer (HAT) processes have been the object of numerous studies showcasing potential homogeneous photocatalyst tetrabutylammonium decatungstate (TBADT) for functionalization C(sp3)-H bonds. However, to translate these into large-scale industrial processes, careful considerations catalyst loading, cost, and removal are required. This work presents organic solvent nanofiltration (OSN) as an answer reduce TBADT consumption, increase its turnover number lower concentration in product solution, thus enabling photocatalytic HAT-based transformations. The operating parameters a suitable membrane recovery acetonitrile were optimized. Continuous alkylation amination reactions carried out with in-line via two OSN steps. Promisingly, observed yields recycling comparable those performed pristine TBADT, therefore highlighting that not only (>99%, TON > 8400) is possibility, but also it does happen at expense reaction performance.

Language: Английский

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Efficient C(sp³)−H Carbonylation of Light and Heavy Hydrocarbons with Carbon Monoxide via Hydrogen Atom Transfer Photocatalysis in Flow**

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(36)

Published: July 17, 2023

Abstract Despite their abundance in organic molecules, considerable limitations still exist synthetic methods that target the direct C−H functionalization at sp 3 ‐hybridized carbon atoms. This is even more case for light alkanes, which bear some of strongest bonds known Nature, requiring extreme activation conditions are not tolerant to most molecules. To bypass these issues, chemists rely on prefunctionalized alkyl halides or organometallic coupling partners. However, new regioselectively a variety different scaffolds would be great added value, only late‐stage biologically active molecules but also catalytic upgrading cheap and abundant hydrocarbon feedstocks. Here, we describe general, mild scalable protocol enables C(sp )−H carbonylation saturated hydrocarbons, including natural products using photocatalytic hydrogen atom transfer (HAT) gaseous monoxide (CO). Flow technology was deemed crucial enable high gas‐liquid mass rates fast reaction kinetics, needed outpace deleterious pathways, leverage safe process.

Language: Английский

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