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

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(22), С. 15331 - 15344

Опубликована: Май 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.

Язык: Английский

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Strategies and Mechanisms of First-Row Transition Metal-Regulated Radical C–H Functionalization

Chemical Reviews, Год журнала: 2024, Номер 124(17), С. 10192 - 10280

Опубликована: Авг. 8, 2024

Radical C–H functionalization represents a useful means of streamlining synthetic routes by avoiding substrate preactivation and allowing access to target molecules in fewer steps. The first-row transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, Cu) are Earth-abundant can be employed regulate radical functionalization. use such is desirable because the diverse interaction modes between metal complexes species including addition center, ligand complexes, substitution single-electron transfer radicals hydrogen atom noncovalent complexes. Such interactions could improve reactivity, diversity, selectivity transformations allow for more challenging reactions. This review examines achievements this promising area over past decade, with focus on state-of-the-art while also discussing existing limitations enormous potential high-value regulated these metals. aim provide reader detailed account strategies mechanisms associated

Язык: Английский

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Modulating Decarboxylative Oxidation Photocatalysis by Ligand Engineering of Atomically Precise Copper Nanoclusters

Journal of the American Chemical Society, Год журнала: 2024, Номер unknown

Опубликована: Сен. 19, 2024

Copper nanoclusters (Cu NCs) characterized by their well-defined electronic and optical properties are an ideal platform for organic photocatalysis exploring atomic-level behaviors. However, potential as greener, efficient catalysts challenging reactions like decarboxylative oxygenation under mild conditions remains unexplored. Herein, we present Cu

Язык: Английский

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Photoredox/Nickel-Catalyzed Diastereoselective Allylation of Aldehydes with Morita–Baylis–Hillman Adducts

ACS Catalysis, Год журнала: 2025, Номер 15(10), С. 8303 - 8316

Опубликована: Май 2, 2025

A practical diastereoselective photoredox nickel-mediated allylation of aliphatic and aromatic aldehydes with Morita-Baylis-Hillman (MBH) acetates is reported here. The reaction proceeds under visible-light irradiation using MBH derivatives, which are easily prepared from inexpensive available starting materials, affording functionalized alcohols as a single diastereoisomer (>20:1 for the syn diastereoisomer). popular organic dye 3DPAFIPN used photocatalyst in combination Hantzsch ester presence catalytic amount stable nickel complexes o-phenanthroline ligand. shows broad scope, avoiding use Ni(0), well stoichiometric metal reductants such Zn Mn. relevance was confirmed by products rapid access to α-methylene-β-lactones, useful intermediates synthesis natural or biologically active relevant products. DFT calculations suggest that allyl acetate-coordinated Ni(0) species plays role catalyst cycle operates through Ni(0)-Ni(II)-Ni(I)-Ni(0) pathway.

Язык: Английский

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Visible Light‐Induced Photoredox and Copper‐Catalyzed C−N Cross‐Coupling: A Mechanistic Perspective

European Journal of Organic Chemistry, Год журнала: 2024, Номер 27(11)

Опубликована: Фев. 7, 2024

Abstract The formation of C−N bonds is a vital technique in organic synthesis for creating nitrogen‐containing motifs, which has extensive uses agrochemicals, pharmaceuticals, and natural products. Significant progress been made constructing using transition metal catalysis. Nevertheless, utilizing alkyl substrates the C sp3 −N notable challenge. Synergistic photoredox copper catalysis have proven to be powerful tool tackle this development research domain still its early stages owing chemical technical complexities catalytic process. This review attempts summarize in‐depth mechanistic understanding photoredox/copper dual catalysed coupling reactions taking into consideration recently reported experimental theoretical studies.

Язык: Английский

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Excited-State Nickel-Catalyzed Amination of Aryl Bromides: Synthesis of Diphenylamines and Primary Anilines

Organic Letters, Год журнала: 2024, Номер 26(8), С. 1657 - 1661

Опубликована: Фев. 21, 2024

Excited-state nickel-catalyzed C–N cross-coupling of aryl bromides with sodium azide enables the synthesis diarylamines and primary anilines under mild reaction conditions. The oxidative addition electron-rich low-valent Ni photochemical conditions is endothermic. Herein, we demonstrate a light-mediated electronically rich that yields diarylamines, while electron-deficient gives access to at room temperature.

Язык: Английский

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C(sp³)‐H Functionalization Using Chlorine Radicals

Advanced Synthesis & Catalysis, Год журнала: 2024, Номер 366(13), С. 2898 - 2918

Опубликована: Май 18, 2024

Abstract Converting any desired C−H bond to the intended C−Z in a given organic molecule could be final peak of functionalization methodology. Among three types bonds, ubiquitous C( sp 3 )−H has gained particular attention, especially last two decades. There are different ways transform bonds into bonds. The use chlorine radicals is one these methods with promising future. literature review shows that sources have been used for chlorine, including chloride ions (HCl or salts), coordinated chlorides (transition metal complexes), and (organochlorine compounds). However, HCl FeCl most attention among sources. major convert from radicals: 1) oxidation hydrogen salts, 2) photolysis chloride, 3) transition insertion C−Cl This summarizes published research papers on functionalization. Therefore, chlorination reactions which do not play direct role cleavage within scope this review.

Язык: Английский

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Photoexcitation of Distinct Divalent Palladium Complexes in Cross‐Coupling Amination Under Air

Angewandte Chemie International Edition, Год журнала: 2023, Номер 63(3)

Опубликована: Ноя. 13, 2023

Abstract The development of metal complexes that function as both photocatalyst and cross‐coupling catalyst remains a challenging research topic. So far, progress has been shown in palladium(0) excited‐state transition catalysis for the construction carbon‐carbon bonds where oxidative addition alkyl/aryl halides to zero‐valent palladium (Pd 0 ) is achievable at room temperature. In contrast, analogous process with divalent II uphill endothermic. For first time, we report can act light‐absorbing species undergoes double excitation realize carbon‐nitrogen (C−N) cross‐couplings under air. Differently substituted aryl be applied mild, selective amination using acetate Density functional theory studies supported by mechanistic investigations provide insight into reaction mechanism.

Язык: Английский

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Visible-Light-Induced Hydrogen Atom Transfer En Route to Exocylic Alkenylation of Cyclic Ethers Enabled by Electron Donor–Acceptor Complex

Organic Letters, Год журнала: 2023, Номер 25(42), С. 7727 - 7732

Опубликована: Окт. 16, 2023

An electron donor-acceptor (EDA)-triggered hydrogen atom transfer (HAT) process is developed for the efficient generation of an α-alkoxy radical from cyclic ethers to synthesize exocyclic alkenylated with exclusive E-selectivity. A judiciously chosen pair (DABCO and maleimide) serves as desired HAT reagent under visible light irradiation without using any photocatalyst or peroxide. wide variety substrates were explored demonstrate diverse applicability practical viability this cross-dehydrogenative transformation. Detailed mechanistic studies revealed a reaction pathway oxidative environment.

Язык: Английский

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Visible‐Light Activation of Diorganyl Bis(pyridylimino) Isoindolide Aluminum(III) Complexes and Their Organometallic Radical Reactivity

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(19)

Опубликована: Март 21, 2024

Abstract We report on the synthesis and characterization of a series (mostly) air‐stable diorganyl bis(pyridylimino) isoindolide (BPI) aluminum complexes their chemistry upon visible‐light excitation. The redox non‐innocent BPI pincer ligand allows for efficient charge transfer homolytic processes title compounds. This makes them universal platform generation carbon‐centered radicals. photo‐induced cleavage Al−C bonds was investigated by means stationary transient UV/Vis spectroscopy, spin trapping experiments, as well EPR NMR spectroscopy. experimental findings were supported quantum chemical calculations. Reactivity studies enabled utilization reactants in tin‐free Giese‐type reactions carbonyl alkylations under ambient conditions, which both indicated radical‐polar crossover behavior. A deeper understanding physical fundamentals photochemical process provided, furnishing turn new strategy to control reactivity bench‐stable organometallics.

Язык: Английский

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