Suzuki-type cross-coupling of alkyl trifluoroborates with acid fluoride enabled by NHC/photoredox dual catalysis

Huang, Hua; Dai, Qing‐Song; Leng, Hai‐Jun; Li, Qingzhu; Yang, Shuangqiao; Tao, Ying-Mao; Zhang, Xiang; Qi, Ting; Li, Junlong

doi:10.1039/d1sc06102j

Cited by 59 publications

(21 citation statements)

References 90 publications

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“…In this catalytic cycle, sensitization of an NHC catalyst induced a SET process with an acyl fluoride, leading to subsequent radical−radical recombination between ketyl and benzyl radicals. 115 Although the highest yield was observed with [Ir(dtbbpy)(ppy) 2 ]PF 6 , 4CzIPN still produced a moderate yield of 25%. DFT calculations also showed that the azolium intermediates had a lower triplet energy level than the PCs, confirming that triplet sensitization is possible.…”

Section: ■ E → Z Isomerization Of Olefinsmentioning

confidence: 93%

“…Finally, the Li group reported a photocatalyzed Suzuki-type coupling involving potassium trifluoroborates and N -heterocyclic carbenes (NHCs) (Scheme ). In this catalytic cycle, sensitization of an NHC catalyst induced a SET process with an acyl fluoride, leading to subsequent radical–radical recombination between ketyl and benzyl radicals . Although the highest yield was observed with [Ir(dtbbpy)(ppy) 2 ]PF 6 , 4CzIPN still produced a moderate yield of 25%.…”

Section: Cross-couplingmentioning

confidence: 99%

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Thermally Activated Delayed Fluorescence Sensitizers As Organic and Green Alternatives in Energy-Transfer Photocatalysis

Hojo

Polgar

Hudson

2022

ACS Sustainable Chem. Eng.

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Photocatalysis has captured the imagination of synthetic chemists and is poised to become a staple of the fine chemical industry. Over the past decade, the subfield of energytransfer (EnT) catalysis has expanded dramatically, harnessing the excited states of a photosensitizer to unlock a variety of redox-neutral, radical-based reactivities in a mild and selective fashion. However, many of the developments in this discipline rely on precious rare earth metals such as iridium. This perspective will highlight the rise of thermally activated delayed fluorescence (TADF) materials as metalfree alternatives in EnT photocatalysis for organic transformations. Emphasis will be placed on the recent progress of cycloadditions, E/Z isomerization of olefins, and other radical-initiated processes; all mediated by the mechanism of Dexter energy transfer. The tunable excited-state energetics and dynamics of TADF materials allow them to effectively compete with iridium-based sensitizers, indicating their promise as green alternatives in organocatalysis.

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Section: ■ E → Z Isomerization Of Olefinsmentioning

confidence: 93%

Section: Cross-couplingmentioning

confidence: 99%

Thermally Activated Delayed Fluorescence Sensitizers As Organic and Green Alternatives in Energy-Transfer Photocatalysis

Hojo

Polgar

Hudson

2022

ACS Sustainable Chem. Eng.

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“…The photoredox catalysis cycle is closed by the SET reduction of the acyl azolium intermediate, providing the corresponding ketyl radical. Using the same strategy with alkyl trifluoroborates and acid fluorides as substrates, Li established an NHC/photoredox dual-catalysis system which enables rapid access to various ketones . Recently, Ohmiya and co-workers demonstrated a visible-light-driven silyl radical generation with silylboronates as the substrates .…”

Section: Ketyl Radicals Generated Via Single-electron Reduction Using...mentioning

confidence: 99%

Radical NHC Catalysis

2022

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Radical/radical cross-coupling reactions represent an efficient and straightforward approach for the construction of chemical bonds and accordingly have drawn increasing attention over the past decades. In order to achieve synthetically useful transformations, a persistent radical should be coupled with a transient radical in accordance with the persistent radical effect (PRE). However, known transient radicals outnumber by far the known types of free persistent radicals, which limits the widespread application of the PRE, until today. Thus, the development of efficient cross-coupling reactions between transient radicals has been in focus, and meanwhile transition-metal catalysis has been successfully implemented to artificially prolong radical lifetimes, allowing their utilization in formal radical/radical cross-couplings. Complementary research in the field recently uncovered that organocatalytically generated NHC-derived ketyl radicals are a type of catalytically generated free persistent radicals. NHC-catalyzed radical transformations of aldehydes and carboxylic acid derivatives have enabled the disclosure of an ever-increasing number of interesting reactions, which are different from traditional NHC-catalyzed ionic processes, offering otherwise inaccessible activation modes. These discoveries have opened a door to NHC organocatalysis for the manipulation of radical reactions. Due to its obvious potential in synthetic organic chemistry, it is timely to provide a perspective on this emerging field.

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“…Recently, Li developed a NHC/photoredox dual catalytic cross-coupling of alkyl trifluoroborates with acid fluorides, providing an alternative solution to the classical acylative Suzuki coupling chemistry (Scheme 32). 44 Scheme 32 NHC/photoredox catalyzed Suzuki-type cross-coupling between alkyl trifluoroborates and acid fluorides 44…”

Section: Organoborane Reagentsmentioning

confidence: 99%

Research Progress on N-Heterocyclic Carbene Catalyzed Reactions for Synthesizing Ketones through Radical Mechanism

Wan

Yang

2022

Synthesis

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Recently NHC-catalyzed radical cross-coupling reactions have sprung up, which provided an efficient method to access ketones from aldehydes or carboxylic acid derivatives with sp3-hybridized carbon radical precursors. It has indirectly solved the limitation of coupling partners scope in NHC umpolung catalysis of aldehydes. In this short review, we present some of the recent advances in NHC-catalyzed radical reactions, with a focus on the construction of C-C(CO) bond.

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Suzuki-type cross-coupling of alkyl trifluoroborates with acid fluoride enabled by NHC/photoredox dual catalysis

Abstract: The Suzuki–Miyaura cross-coupling of C(sp3)-hybridised boronic compounds still remains a challenging task, thereby hindering the broad application of alkyl boron substrates in carbon-carbon bond-forming reactions. Herein, we developed an NHC/photoredox...

Cited by 59 publications

References 90 publications

Thermally Activated Delayed Fluorescence Sensitizers As Organic and Green Alternatives in Energy-Transfer Photocatalysis

Thermally Activated Delayed Fluorescence Sensitizers As Organic and Green Alternatives in Energy-Transfer Photocatalysis

Radical NHC Catalysis

Research Progress on N-Heterocyclic Carbene Catalyzed Reactions for Synthesizing Ketones through Radical Mechanism

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