Lewis Base–Boryl Radicals Enabled Borylation Reactions and Selective Activation of Carbon–Heteroatom Bonds

Accounts of Chemical Research, Год журнала: 2022, Номер 56(2), С. 169 - 186

Опубликована: Дек. 26, 2022

ConspectusThe past decades have witnessed tremendous progress on radical reactions. However, in comparison with carbon, nitrogen, oxygen, and other main group element centered radicals, the synthetic chemistry of boron radicals was less studied, mainly due to high electron-deficiency instability such 3-center-5-electron species. In 1980s, Roberts co-workers found that coordination a Lewis base (amines or phosphines) center could form 4-center-7-electron boryl (Lewis base-boryl LBRs) are be more stable. only limited applications were developed. 2008, Curran achieved breakthrough discovery N-heterocyclic carbene (NHC) which enable range reduction polymerization Despite these exciting findings, powerful valuable LBRs would expected, given structures reactivities easily modulated, provide ample opportunities discover new this Account, summary our key contributions LBR-enabled borylation reactions selective activation inert carbon-heteroatom bonds will presented.Organoboron compounds shown versatile chemical society, their syntheses rely principally ionic The development mechanistically different allows synthesizing products inaccessible by traditional methods. For purpose, we progressively developed series NHC-boryl mediated chemo-, regio-, stereoselective alkenes alkynes, wide variety structurally diverse organoboron molecules successfully prepared. utility borylated also demonstrated. Furthermore, disclosed photoredox protocol for oxidative generation enabled useful defluoroborylation arylboration reactions.Selective bond is an ideal way convert simple starting materials value-added products, while cleavage bonds, particular chemoselectivity control when multiple identical present similar environments, remains long-standing challenge. We envisaged finely tuning properties might solution address Recently, 4-dimethylaminopyridine (DMAP)-boryl promoted sequential C-F functionalization trifluoroacetic acid derivatives, α-C-F selectively snipped via spin-center shift mechanism. This strategy enables facile conversion abundantly available highly mono- difluorinated molecules. Encouraged finding, further three-step sequence construct all-carbon quaternary centers from trichloromethyl groups, where three C-Cl cleaved rational choice suitable precursors each step. dehydroxylative alkylation α-hydroxy carboxylic derivatives achieved, allowing efficient some biomass platform value products.

Язык: 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, Год журнала: 2022, Номер 145(2), С. 991 - 999

Опубликована: Дек. 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.

Язык: Английский

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Radical hydroboration for the synthesis of organoboron compounds

Chemical Communications, Год журнала: 2024, Номер 60(32), С. 4275 - 4289

Опубликована: Янв. 1, 2024

This review describes the recent research on radical hydroboration, which covers different boron sources including N-heterocyclic carbene borane, bis(pinacolato)diboron and pinacolborane, as well strategies in boryl generation.

Язык: Английский

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Charge Separation in Metal‐Organic Framework Enables Heterogeneous Thiol Catalysis

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(25)

Опубликована: Апрель 19, 2023

Photoinduced metal-organic framework (MOF) enabled heterogeneous thiol catalysis has been achieved for the first time. MOF Zr-TPDCS-1, consisting of Zr6 -clusters and TPDCS linkers (TPDCS=3,3'',5,5''-tetramercapto[1,1':4',1''-terphenyl]-4,4''-dicarboxylate), effectively catalyzed borylation, silylation, phosphorylation, thiolation organic molecules. Upon irradiation, fast electron transfer from to -cluster is believed facilitate formation thiyl radical, a hydrogen atom catalyst, which competently abstracts borane, silane, phosphine, or generating corresponding element radical engender chemical transformations. The elaborate control experiments evidenced generation radicals in illustrated reaction pathway. gram-scale worked well, product was conveniently separated via centrifugation vacuum with turnover number (TON) ≈3880, highlighting practical application potential thiyl-radical catalysis.

Язык: Английский

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A green and facile photochemical thiolate-catalyzed strategy for borylation of aryl fluorides with NHC–borane

Organic Chemistry Frontiers, Год журнала: 2024, Номер 11(5), С. 1462 - 1468

Опубликована: Янв. 1, 2024

Mild conditions, no photocatalyst, broad substrate scope.

Язык: Английский

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Exhaustive Hydrodefluorination or Deuterodefluorination of Trifluoromethylarenes via Metal-Free Photoredox Catalysis

Organic Letters, Год журнала: 2024, Номер 26(4), С. 928 - 932

Опубликована: Янв. 25, 2024

Perfluoroalkyl compounds are persistent environmental pollutants due to their chemical and thermal stability. Hydrodefluorination is one of the most promising strategies for disposal fluorine-containing compounds, which has attracted much attention from a broad spectrum scientific communities. Herein, we disclose metal-free, visible-light-promoted protocol exhaustive hydrodefluorination wide variety trifluoromethylarenes with up 95% yields. Moreover, methyl-d3 groups can be obtained via deuterium water D ratio 94%.

Язык: Английский

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A general photo-induced wide-scope regioselective hydroboration of alkenes without using a photocatalyst or an external initiator

Green Chemistry, Год журнала: 2022, Номер 24(18), С. 7113 - 7121

Опубликована: Янв. 1, 2022

A general photo-induced regioselective hydroboration of alkenes without photocatalyst or an external initiator has been developed through in situ formed boryl radicals. Thiol plays the dual role as a proton donor and hydrogen atom transfer catalyst.

Язык: Английский

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C4-Selective C–H Borylation of Pyridinium Derivatives Driven by Electron Donor–Acceptor Complexes

Organic Letters, Год журнала: 2022, Номер 24(51), С. 9452 - 9457

Опубликована: Дек. 16, 2022

The photoinduced C4-selective C-H borylation of pyridines was achieved using electron donor-acceptor complexes derived from a Lewis base and N-amidopyridinium salts under external oxidant- photocatalyst-free conditions. Notably, the nucleophilic character phosphite-ligated boryl radicals enables addition radical to position C4 pyridinium afford C4-borylated heteroarenes that are otherwise difficult obtain. This approach provides versatile platform for installation both phosphite- amine-coordinated boron groups on series mild conditions, demonstrating excellent C4-positional selectivity pyridine scaffolds.

Язык: Английский

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Transition‐Metal‐Free Radical Borylation Reactions

European Journal of Organic Chemistry, Год журнала: 2023, Номер 26(12)

Опубликована: Фев. 13, 2023

Abstract Organoboron compounds are versatile synthons in synthetic chemistry, materials science, and medicinal chemistry. The preparation of them often requires either reactive organometallic reagents or transition metals. In recent years, transition‐metal‐free borylation methodologies using radical chemistry for C−B bond formation have attracted much attention developed rapidly, which circumvents the use preformed reagents. Various successful approaches from different precursors (such as carboxylic acids, amines alcohols, abundant nature) through thermochemical, photochemical electrochemical pathways been developed. Therefore, this review, we hope to provide an overview advances discovery, development, mechanistic study processes.

Язык: Английский

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Facile Borylation of Alkenes, Alkynes, Imines, Arenes and Heteroarenes with N‐Heterocyclic Carbene‐Boranes and a Heterogeneous Semiconductor Photocatalyst

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(39)

Опубликована: Авг. 9, 2023

Although the development of radical chain and photocatalytic borylation reactions using N-heterocyclic carbene (NHC)-borane as boron source is remarkable, persistent problems, including use hazardous high-energy initiators or recyclability photostability issues soluble homogeneous photocatalysts, still leave great room for further in a sustainable manner. Herein, we report conceptually different approach toward highly functionalized organoborane synthesis by recoverable ultrathin cadmium sulfide (CdS) nanosheets heterogeneous photocatalyst, general mild platform that enables regioselective wide variety alkenes (arylethenes, trifluoromethylalkenes, α,β-unsaturated carbonyl compounds nitriles), alkynes, imines electron-poor aromatic rings with NHC-borane boryl precursor. Mechanistic studies density functional theory (DFT) calculations reveal both photogenerated electrons holes on CdS fully perform their own roles, thereby resulting enhancement activity stability CdS.

Язык: Английский

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