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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Switchable divergent di- or tricarboxylation of allylic alcohols with CO2

Chem, Год журнала: 2024, Номер 10(3), С. 938 - 951

Опубликована: Янв. 10, 2024

Язык: Английский

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Photocatalytic Carboxylation of C−N Bonds in Cyclic Amines with CO₂ by Consecutive Visible‐Light‐Induced Electron Transfer

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(11)

Опубликована: Янв. 21, 2023

Abstract Visible‐light photocatalytic carboxylation with CO 2 is highly important. However, it still remains challenging for reluctant substrates low reduction potentials. Herein, we report a novel of C−N bonds in cyclic amines via consecutive photo‐induced electron transfer (ConPET). It also the first reductive ring‐opening reaction azetidines, pyrrolidines and piperidines. This strategy practical to transform variety easily available valuable β‐, γ‐, δ‐ ϵ‐amino acids moderate‐to‐excellent yields. Moreover, method features mild transition‐metal‐free conditions, high selectivity, good functional‐group tolerance, facile scalability product derivations. Mechanistic studies indicate that ConPET might be key generating reactive photocatalysts, which enable activation generate carbon radicals carbanions as intermediates.

Язык: Английский

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Regio- and Stereoselective Reductive Coupling of Alkynes and Crotononitrile

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(50), С. 23001 - 23009

Опубликована: Дек. 8, 2022

A new regio- and stereoselective reductive coupling of alkynes crotononitrile has been developed via visible light organophotoredox cobalt dual catalysis. variety enantioenriched homoallylic nitriles bearing a stereodefined trisubstituted alkene have easily synthesized with good to excellent (up >20:1 rr), stereo- (>20:1 E/Z), enantioselectivity 98% ee) control under mild conditions. The corresponding nitrile products were smoothly converted into various chiral building blocks. Remarkably, simple organic base together water utilized as hydrogen sources in this photoinduced reaction.

Язык: Английский

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Regiodivergent electroreductive defluorinative carboxylation ofgem-difluorocyclopropanes

Green Chemistry, Год журнала: 2023, Номер 25(8), С. 3095 - 3102

Опубликована: Янв. 1, 2023

A regiodivergent electrochemical defluorocarboxylation of gem -difluorocyclopropanes is realized, providing access to branched and linear carboxylated monofluorinated alkenes.

Язык: Английский

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Electrochemically Driven Deoxygenative Borylation of Alcohols and Carbonyl Compounds

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(31), С. 16966 - 16972

Опубликована: Июль 27, 2023

We present a new, unified approach for the transformation of benzylic and allylic alcohols, aldehydes, ketones into boronic esters under electroreductive conditions. Key to our strategy is use readily available pinacolborane, which serves both as an activator electrophile by first generating redox-active trialkylborate species then delivering desired deoxygenatively borylated product. This applicable variety substrates can be employed late-stage functionalization complex molecules.

Язык: Английский

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Nickel-Catalyzed Deoxygenative Disulfuration of Alcohols to Access Unsymmetrical Disulfides

ACS Catalysis, Год журнала: 2024, Номер 14(9), С. 6451 - 6461

Опубликована: Апрель 12, 2024

Given the abundance of alcohol feedstocks and significance disulfides, we herein report a nickel-catalyzed direct deoxygenative disulfuration alcohols with trisulfide dioxides to access wide range disulfide molecules without cumbersome decoration coupling partners. The use readily available dicyclohexylcarbodiimide form transient isoureas provides activation high bond dissociation energy C–O bond, which facilitates straightforward conversion nonderivatized forge C–SS bond. Notably, this method obviates preactivation multistep procedure catalytic turnover under exogenous ligand base-free conditions, featuring broad substrate scope functional group compatibility. It thus offers robust alternative existing methods for precise construction versatile compounds from more abundant commercially substrates. synthetic utility was further showcased by successful gram-scale experiments structurally complex pharmaceuticals.

Язык: Английский

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Alcohols as Alkyl Synthons Enabled by Photoredox-Catalyzed Deoxygenative Activation

ACS Catalysis, Год журнала: 2024, Номер 14(17), С. 13451 - 13496

Опубликована: Авг. 26, 2024

Alcohols are abundant with versatile structural variety and have ample use as pivotal functional groups in numerous organic processes. Because of their frequent occurrence enumerable natural products, bioactive molecules, medicinal components, alcohol functionalities provide a promising scope research to advance the operational diversity for improving clinical success. Recent years witnessed design modern C–C C–heteroatom bond-forming approaches easily accessible commercially available unactivated aliphatic alcohols native adaptive sp3 handles, hence offering groundbreaking transformative pathways functionalization complex molecular architectures. The judicial application appropriate activating generate alkyl radical from through C–O bond fragmentation employ it potential alkylating agent unfolds unique synthetic strategies, thereby replacing obvious requirement halides. This review elaborately discusses recent trends regarding using C(sp3)-centered various chemical transformations by exploiting different activation modes disrupter under photoredox catalysis. presentation is organized nature scaffolds, kind formation, progress achieved this domain since original discovery providing illustrative examples mechanistic details, focus on difficulties future prospects.

Язык: Английский

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Selective Reductive Coupling of Vinyl Azaarenes and Alkynes via Photoredox Cobalt Dual Catalysis

Angewandte Chemie International Edition, Год журнала: 2022, Номер 62(1)

Опубликована: Сен. 30, 2022

A visible light-induced Co-catalyzed highly regio- and stereoselective reductive coupling of vinyl azaarenes alkynes has been developed. Notably, Hünig's base together with simple ethanol successfully applied as the hydrogen sources instead commonly used Hantzsch esters in this catalytic photoredox reaction. This approach considerable advantages for straightforward synthesis stereodefined multiple substituted alkenes bearing an azaarene motif, such excellent regioselectivity (>20 : 1 >30 examples) stereoselectivity E/Z), broad substrate scope good functional group compatibility under mild reaction conditions, which utilized concise natural product monomorine I. reasonable pathway involving protolysis cobaltacyclopentene intermediate proposed based on mechanistic studies.

Язык: Английский

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Site‐Selective Pyridine C−H Alkylation with Alcohols and Thiols via Single‐Electron Transfer of Frustrated Lewis Pairs

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(51)

Опубликована: Окт. 31, 2022

A unified strategy for the deoxygenative or desulfurative pyridylation of various alcohols and thiols has been developed through a single-electron transfer (SET) process frustrated Lewis pairs (FLPs) derived from pyridinium salts PtBu3 . Mechanistic studies revealed that N-amidopyridinium serve as effective acids formation FLPs with , generated phosphine radical cation ionically couples in situ xanthate, eventually affording alkyl facile β-scission under photocatalyst-free conditions. The reaction efficiency was further accelerated by visible-light irradiation. This method is conceptually appealing using encounter complexes FLP chemistry to promote SET, which provides previously unrecognized opportunity selective heteroarylation diverse range functional groups, even complex settings mild

Язык: Английский

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