Recent Progress in Fragmentation of Katritzky Salts Enabling Formation of C–C, C–B, and C–S Bonds

Gao, Yuan; Jiang, Songwei; Mao, Nian-Dong; Xiang, Huan; Duan, Jilong; Ye, Xiang‐Yang; Wang, Liwei; Ye, Yang; Xie, Tian

doi:10.1007/s41061-022-00381-x

Cited by 32 publications

(29 citation statements)

References 84 publications

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“…Katritzky salts are pyridinium salts that are easily prepared by the condensation of primary amines with pyrylium salts. These salts can undergo a reductive deamination (via SET) to afford alkyl radicals . In 2020, Hong reported an NHC-catalyzed radical cross-coupling of aldehydes with pyridinium salts as the alkyl radical precursors (Scheme ).…”

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

confidence: 99%

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

confidence: 99%

“…These salts can undergo a reductive deamination (via SET) to afford alkyl radicals. 76 In 2020, Hong reported an NHC-catalyzed radical cross-coupling of aldehydes with pyridinium salts as the alkyl radical precursors (Scheme 10). 77 The reaction showed a broad functional group tolerance.…”

Section: Set Oxidation Of Breslowmentioning

confidence: 99%

Radical NHC Catalysis

2022

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“…Aryl groups sophisticatedly mediate the bioactivities of drug compounds and physical properties of materials. 20 To validate the feasibility of arylboration protocols, Brown 21 initially focused on the arylboration of alkenes with aryl bromides and B 2 pin 2 under Ni-catalyzed conditions, which allowed for the highly stereoselective arylboration of unactivated olefins (Scheme 4). A simple nickel catalyst was used in these reactions that tolerated a wide range of cyclic or chain alkenes and substituted aryl bromides ( 1–7 ).…”

Section: (Hetero)arylborationmentioning

confidence: 99%

Recent progress in nickel-catalyzed carboboration of alkenes

Lin

Mao

et al. 2022

Org. Biomol. Chem.

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“…Among the known methods, those that employ functionalized precursors to deliver an alkyl group are the most prevalent. Alkylboranes are widely used for alkylation assisted by transition metals or strong oxidants. , The N -hydroxy phthalimide esters are alternative alkylating reagents formed by the combination of NHPI and the corresponding carboxylic acids. − Other reagents include alkylated dihydropyridines (DHPs) − and Katritzky salts. − Decarboxylative alkylation with corresponding carboxylic acids − and decarbonylative alkylation − with aldehydes are also well-explored. The development of alkylation strategies that do not require pre-functionalized precursors, harsh oxidizing conditions, or expensive/highly engineered photocatalysts represents an advancement in this area.…”

Section: Introductionmentioning

confidence: 99%

Pd-Catalyzed Photochemical Alkylative Functionalization of C═C and C═N Bonds

et al. 2023

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The development of excited-state palladium-catalyzed alkylative cyclization of acrylamides and the alkylation of quinoxalinones is described. The application of a variety of primary, secondary, and tertiary unactivated alkyl halides as alkyl radical precursors and the use of a simple catalyst system are the highlights of this reactivity manifold. The reactions exhibit wide scope, occur under mild conditions, and furnish the products in excellent yields.

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Recent Progress in Fragmentation of Katritzky Salts Enabling Formation of C–C, C–B, and C–S Bonds

Cited by 32 publications

References 84 publications

Radical NHC Catalysis

Radical NHC Catalysis

Recent progress in nickel-catalyzed carboboration of alkenes

Pd-Catalyzed Photochemical Alkylative Functionalization of C═C and C═N Bonds

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