Radical Relay Trichloromethylacylation of Alkenes through N-Heterocyclic Carbene Catalysis DOI

Mayu Kusakabe,

Kazunori Nagao, Hirohisa Ohmiya

et al.

Organic Letters, Journal Year: 2021, Volume and Issue: 23(18), P. 7242 - 7247

Published: Aug. 31, 2021

N-Heterocyclic carbene catalysis enabling vicinal trichloromethylacylation of alkenes using tetrachloromethane and aldehydes has been developed. The reaction involves single electron transfer from the enolate form Breslow intermediate to generate persistent intermediate-derived ketyl radical a transient trichloromethyl radical. After addition an alkene, prolonged alkyl is preferentially captured by over leading atom product.

Language: Английский

Carbene and photocatalyst-catalyzed decarboxylative radical coupling of carboxylic acids and acyl imidazoles to form ketones DOI Creative Commons
Shi‐Chao Ren, Xing Yang, Bivas Mondal

et al.

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

Published: May 23, 2022

The carbene and photocatalyst co-catalyzed radical coupling of acyl electrophile a precursor is emerging as attractive method for ketone synthesis. However, previous reports mainly limited to prefunctionalized precursors two-component coupling. Herein, an N-heterocyclic catalyzed decarboxylative carboxylic acids imidazoles disclosed, in which the are directly used precursors. could also be generated situ by reaction acid with CDI thus furnishing formally two acids. In addition, successfully extended three-component using alkene third partner via relay process. mild conditions, operational simplicity, use reacting partners make our powerful strategy construction complex ketones from readily available starting materials, late-stage modification natural products medicines.

Language: Английский

Citations

85
NHC and visible light-mediated photoredox co-catalyzed 1,4-sulfonylacylation of 1,3-enynes for tetrasubstituted allenyl ketones DOI Creative Commons
Lihong V. Wang,

Ruiyang Ma,

Jiaqiong Sun

et al.

Chemical Science, Journal Year: 2022, Volume and Issue: 13(11), P. 3169 - 3175

Published: Jan. 1, 2022

The modulation of selectivity highly reactive carbon radical cross-coupling for the construction C-C bonds represents a challenging task in organic chemistry. N-Heterocyclic carbene (NHC) catalyzed transformations have opened new avenue acyl With this method, selective an with alkyl efficient was successfully realized. However, reaction radicals vinyl has been much less investigated. We herein describe NHC and visible light-mediated photoredox co-catalyzed 1,4-sulfonylacylation 1,3-enynes, providing structurally diversified valuable tetrasubstituted allenyl ketones. Mechanistic studies indicated that ketyl are formed from aroyl fluorides via oxidative quenching photocatalyst excited state, generated chemo-specific sulfonyl addition to finally, key provides

Language: Английский

Citations

73
Photoinduced Acylations Via Azolium-Promoted Intermolecular Hydrogen Atom Transfer DOI
Joshua L. Zhu,

Cullen R. Schull,

Anthony T. Tam

et al.

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(3), P. 1535 - 1541

Published: Jan. 10, 2023

Photoinduced hydrogen atom transfer (HAT) has been developed as a powerful tool to generate synthetically valuable radical species. The direct photoexcitation of ketones known promote HAT or acyl radicals through Norrish-type pathways, but these modalities remain severely limited by side reactions. We report herein catalyst- and transition metal-free method for the acylation C-H bonds that leverages unique properties stable, isolable azolium Specifically, salts are shown undergo an intermolecular regioselective upon LED irradiation with range substrates bearing active followed C-C bond formation afford ketones. Experimental computational studies support facile intersystem crossing access triplet diradical species selective radical-radical cross-coupling.

Language: Английский

Citations

52
Recent advances in combining photo- and N-heterocyclic carbene catalysis DOI Creative Commons
Xiaochen Wang,

Senhui Wu,

Rongxin Yang

et al.

Chemical Science, Journal Year: 2023, Volume and Issue: 14(46), P. 13367 - 13383

Published: Jan. 1, 2023

This review summarizes recent advances in combining photo- and N-heterocyclic carbene catalysis, as well provides an outlook on future opportunities challenges.

Language: Английский

Citations

43
Radical Reactions with N-Heterocyclic Carbene (NHC)-Derived Acyl Azoliums for Access to Multifunctionalized Ketones DOI

Hui Cai,

Xiaoqun Yang,

Shi‐Chao Ren

et al.

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(11), P. 8270 - 8293

Published: May 13, 2024

As one of the most important key intermediates, NHC-bound acylazolium-based ionic transformations have been intensively explored in past two decades. With expeditious development NHC-catalyzed radical recent years, acylazolium chemistry has reached another level, with number relevant publications increasing significantly. However, a summary focused on acylations NHC-derived acyl azoliums classified according to mechanistic difference not reported. Such detailed classification and deep analysis provide opportunities for better understanding history trend this field. In review, reactions N-heterocyclic carbene (NHC)-derived are systematically introduced. The achievements challenges within area also summarized discussed at end.

Language: Английский

Citations

23
N‐Heterocyclic Carbene Catalyzed Photoenolization/Diels–Alder Reaction of Acid Fluorides DOI Creative Commons
Andreas Mavroskoufis, Keerthana Rajes, Paul Golz

et al.

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 59(8), P. 3190 - 3194

Published: Dec. 9, 2019

Abstract The combination of light activation and N‐heterocyclic carbene (NHC) organocatalysis has enabled the use acid fluorides as substrates in a UVA‐light‐mediated photochemical transformation previously observed only with aromatic aldehydes ketones. Stoichiometric studies TD‐DFT calculations support mechanism involving photoactivation an ortho ‐toluoyl azolium intermediate, which exhibits “ketone‐like” reactivity under UVA irradiation. Using this photo‐NHC catalysis approach, novel photoenolization/Diels–Alder (PEDA) process was developed that leads to diverse isochroman‐1‐one derivatives.

Language: Английский

Citations

132
N-heterocyclic carbene-catalyzed radical reactions DOI

Kun‐Quan Chen,

Sheng He, Qiang Liu

et al.

Science China Chemistry, Journal Year: 2020, Volume and Issue: 64(1), P. 7 - 16

Published: Sept. 29, 2020

Language: Английский

Citations

112
Single‐Electron Transfer Reactions Enabled by N‐Heterocyclic Carbene Organocatalysis DOI
Qing‐Zhu Li, Rong Zeng, Bo Han

et al.

Chemistry - A European Journal, Journal Year: 2020, Volume and Issue: 27(10), P. 3238 - 3250

Published: Oct. 9, 2020

Abstract Over the past decades, N‐heterocyclic carbene (NHC) organocatalysis has undergone a flourish of development on basis closed‐shell reaction paths. By contrast, emerging area single‐electron transfer (SET) reactions enabled by NHC catalysis still remain underdeveloped, but offer plenty opportunities to develop new catalytic modes and useful synthetic methods. A number interesting transformations were triggered SET process from electron‐rich Breslow intermediates various acceptors. In additions, recent studies revealed that radical cations could also be generated reduction electron‐deficient acyl azolium intermediates. These discoveries open avenue for harness reactions. The present review will focus exciting advancements in dynamic organocatalysis.

Language: Английский

Citations

107
Light‐Driven Carbene Catalysis for the Synthesis of Aliphatic and α‐Amino Ketones DOI
Anna V. Bay, Keegan P. Fitzpatrick, Gisela A. González‐Montiel

et al.

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(33), P. 17925 - 17931

Published: June 7, 2021

Single-electron N-heterocyclic carbene (NHC) catalysis has gained attention recently for the synthesis of C-C bonds. Guided by density functional theory and mechanistic analyses, we report light-driven aliphatic α-amino ketones using single-electron NHC operators. Computational experimental results reveal that reactivity key radical intermediate is substrate-dependent can be modulated through steric electronic parameters NHC. Catalyst potential harnessed in visible-light driven generation an acyl azolium species undergoes selective coupling with various partners to afford diverse ketone products. This methodology showcased direct late-stage functionalization amino acids pharmaceutical compounds, highlighting utility

Language: Английский

Citations

95
Light-Driven N-Heterocyclic Carbene Catalysis Using Alkylborates DOI

Yukiya Sato,

Yamato Goto, K. Nakamura

et al.

ACS Catalysis, Journal Year: 2021, Volume and Issue: 11(21), P. 12886 - 12892

Published: Oct. 8, 2021

Radical–radical coupling, the selective reaction between two different radical species, has contributed to methodology for connecting bulky units. Light-driven N-heterocyclic carbene (NHC) organocatalysis is recognized as a state-of-the-art enabling radical–radical coupling. The catalytic process involves forming an acyl azolium intermediate from NHC catalyst and donor, followed by single electron reduction of this key intermediate, which largely dependent on photoredox catalyst. We designed catalysis in direct photoexcitation borate form high reducing agent facilitated event. produces alkyl transfer accomplish This protocol enables cross-coupling alkylborates imidazoles addition relay-type alkylacylations alkenes with imidazoles, affording ketones broad scope.

Language: Английский

Citations

93