Photocatalytic hydrofluoroalkylation of alkenes with carboxylic acids

Nature Chemistry, Journal Year: 2023, Volume and Issue: 15(12), P. 1683 - 1692

Published: Nov. 13, 2023

Language: Английский

---

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

Accounts of Chemical Research, Journal Year: 2022, Volume and Issue: 56(2), P. 169 - 186

Published: Dec. 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.

Language: Английский

---

Photoinduced Hydrodifluoromethylation and Hydromethylation of Alkenes Enabled by Ligand-to-Iron Charge Transfer Mediated Decarboxylation

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(3), P. 1300 - 1310

Published: Jan. 11, 2024

Directly utilizing abundant and inexpensive sources of aliphatic carboxylic acids is highly attractive for the synthesis CF2H- CH3-containing compounds. Herein, we report a versatile photoinduced iron-catalyzed platform hydrodifluoromethylation hydromethylation alkenes without need additional stoichiometric oxidants. These two transformations are accomplished by visible-light-induced ligand-to-iron charge transfer open-shell activation system using industrial chemical difluoroacetic acetic as precursors postulated to operate via difluoromethyl methyl radical-mediated decarboxylation mechanism. Experimental results show that strategy also applicable difunctionalization unactivated alkenes. Meanwhile, this provides viable route pharmaceutically active molecules containing deuterated units. The protocol exhibits several features, including mild reaction conditions, divergent radical precursors, operational simplicity scalability, good chemo- regioselectivity, scalability supported continuous flow technology, ability provide high-value building blocks applications in one step.

Language: Английский

---

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

---

Photoinduced activation of alkyl chlorides

Chemical Society Reviews, Journal Year: 2023, Volume and Issue: 52(17), P. 6120 - 6138

Published: Jan. 1, 2023

In recent years, the activation of unactivated alkyl chlorides through light-induced processes has emerged as a promising field in radical chemistry, and led to new transformations organic synthesis. Direct utilization C(sp3)-hybridized electrophiles enables facile construction carbon-carbon carbon-heteroatom bonds. Furthermore, studies medicinal chemistry indicate that their presence is associated with high levels success clinical trials. This review summarizes advances photoinduced discusses mechanistic aspects underlying these reactions. We anticipate this will serve valuable resource for researchers chemical bond functionalization, inspire considerable developments drug synthesis, materials science other related disciplines.

Language: Английский

---

Aminals as powerful XAT-reagents: activation of fluorinated alkyl chlorides

Chemical Science, Journal Year: 2023, Volume and Issue: 14(12), P. 3229 - 3234

Published: Jan. 1, 2023

Reagents for the activation of C–Cl bond via XAT process are described. The reaction efficiency is based on stereoelectronic effects. method applied to chlorofluorocarbons.

Language: Английский

---

Direct B–H Functionalization of Icosahedral Carboranes via Hydrogen Atom Transfer

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(13), P. 7638 - 7647

Published: March 22, 2023

The efficient and selective functionalization of icosahedral carboranes (C2B10H12) at the boron vertexes is a long-standing challenge owing to presence 10 inert B-H bonds in similar chemical environment. Herein, we report new reaction paradigm for direct via homolysis enabled by nitrogen-centered radical-mediated hydrogen atom transfer (HAT) strategy. Both HAT process carborane bond resulting boron-centered carboranyl radical intermediate have been confirmed experimentally. occurs most electron-rich vertex with lowest dissociation energy (BDE). Using this strategy, diverse derivatization, including thiolation, selenation, alkynylation, alkenylation, cyanation, halogenation, achieved satisfactory yields under photoinitiated condition metal-free redox-neutral fashion. Moreover, synthetic utility current protocol was also demonstrated both scale-up construction carborane-based functional molecules. Therefore, methodology opens pathway functionalization, which distinct from heterolytic mechanism traditional strategies.

Language: Английский

---

Recent Advances in C–H Functionalisation through Indirect Hydrogen Atom Transfer

Molecules, Journal Year: 2023, Volume and Issue: 28(16), P. 6127 - 6127

Published: Aug. 18, 2023

The functionalisation of C–H bonds has been an enormous achievement in synthetic methodology, enabling new retrosynthetic disconnections and affording simple equivalents for synthons. Hydrogen atom transfer (HAT) is a key method forming alkyl radicals from substrates. Classic reactions, including the Barton nitrite ester reaction Hofmann–Löffler–Freytag reaction, among others, provided early examples HAT. However, recent developments photoredox catalysis electrochemistry have made HAT powerful tool capable introducing wide range functional groups into bonds. Moreover, greater mechanistic insights stimulated development increasingly site-selective protocols. Site-selectivity can be achieved through tuning electron density at certain using additives, judicious choice reagent, solvent system. Herein, we describe latest methods functionalizing C–H/Si–H/Ge–H indirect between 2018–2023, as well critical discussion reagents, aspects, substrate scopes, background contexts

Language: Английский

---

Asymmetric Synthesis of α-Chloroamides via Photoenzymatic Hydroalkylation of Olefins

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(11), P. 7191 - 7197

Published: March 5, 2024

Photoenzymatic intermolecular hydroalkylations of olefins are highly enantioselective for chiral centers formed during radical termination but poorly selective set in the C–C bond-forming event. Here, we report evolution a flavin-dependent "ene"-reductase to catalyze coupling α,α-dichloroamides with alkenes afford α-chloroamides good yield excellent chemo- and stereoselectivity. These products can serve as linchpins synthesis pharmaceutically valuable motifs. Mechanistic studies indicate that formation occurs by exciting charge-transfer complex templated protein. Precise control over orientation molecules within potentially accounts observed The work expands types motifs be prepared using photoenzymatic catalysis.

Language: Английский

---

Photocatalyst-Free Activation of Sulfamoyl Chlorides for Regioselective Sulfamoyl-Oximation of Alkenes via Hydrogen Atom Transfer (HAT) and Halogen-Atom Transfer (XAT) Relay Strategy

Organic Letters, Journal Year: 2024, Volume and Issue: 26(10), P. 2062 - 2067

Published: March 7, 2024

The use of readily available and diverse sulfamoyl chlorides for synthesizing sulfonamide compounds presents an intriguing, yet significantly underexplored strategy. Activating via single-electron reduction poses challenges due to their high potential. Alternatively, the SO2–Cl bond in could be cleaved by XAT. However, existing methodologies have been limited either photocatalyst or monofunctionalization activated alkenes. Here, we report a regioselective sulfamoyl-oximation alkenes involving activation through HAT XAT relay strategy photocatalyst-free way. key this success lies dual roles tert-butyl nitrite (TBN), which not only serves as source oximes but also acts reagent generate crucial reactive species. exclusion metal catalysts photosensitizers utilizing light energy renders protocol versatile universally applicable broad range structurally oxime-containing alkyl sulfonamides.

Language: Английский

---