Iminyl-Radical-Triggered C–C Bond Cleavage of Cycloketone Oxime Derivatives: Generation of Distal Cyano-Substituted Alkyl Radicals and Their Functionalization

Xiao, Tiebo; Huang, Hongtai; Anand, Devireddy; Zhou, Lei

doi:10.1055/s-0039-1690844

Cited by 84 publications

(38 citation statements)

References 54 publications

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“…There is a growing interest in the development of synthetic methods that combine the C–H/C–C bond cleavage of strained carbo- or heterocycles by means of radical intermediates [ 24 , 75 , 76 ]. There are several approaches in this field, depending on the way to generate the reactive radical species, for instance through the use of photochemical catalysts or the introduction of radical promoters in the reaction mixture.…”

Section: Synthetic Methodsology Involving C–h Functionalization Alomentioning

confidence: 99%

“…Nitrogen-centered radical precursors have proven to be versatile and useful species in organic synthesis [ 82 , 83 , 84 ]. More specifically iminyl radical precursors have been utilized to generate cyanoalkylradical intermediates that can be further cross-coupled [ 75 , 85 ]. Besides, the alkylation of aromatic heterocycles through the addition of radicals, generally known as Minisci-type alkylation, is an interesting approach for C–H functionalization [ 86 ].…”

Section: Synthetic Methodsology Involving C–h Functionalization Alomentioning

confidence: 99%

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Recent Advances on Synthetic Methodology Merging C–H Functionalization and C–C Cleavage

Azizollahi

Garcı́a-López

2020

Molecules

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The functionalization of C–H bonds has become a major thread of research in organic synthesis that can be assessed from different angles, for instance depending on the type of catalyst employed or the overall transformation that is carried out. This review compiles recent progress in synthetic methodology that merges the functionalization of C–H bonds along with the cleavage of C–C bonds, either in intra- or intermolecular fashion. The manuscript is organized in two main sections according to the type of substrate in which the cleavage of the C–C bond takes place, basically attending to the scission of strained or unstrained C–C bonds. Furthermore, the related research works have been grouped on the basis of the mechanistic aspects of the different transformations that are carried out, i.e.,: (a) classic transition metal catalysis where organometallic intermediates are involved; (b) processes occurring via radical intermediates generated through the use of radical initiators or photochemically; and (c) reactions that are catalyzed or mediated by suitable Lewis or Brønsted acid or bases, where molecular rearrangements take place. Thus, throughout the review a wide range of synthetic approaches show that the combination of C–H and C–C cleavage in single synthetic operations can serve as a platform to achieve complex molecular skeletons in a straightforward manner, among them interesting carbo- and heterocyclic scaffolds.

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Section: Synthetic Methodsology Involving C–h Functionalization Alomentioning

confidence: 99%

Section: Synthetic Methodsology Involving C–h Functionalization Alomentioning

confidence: 99%

Recent Advances on Synthetic Methodology Merging C–H Functionalization and C–C Cleavage

Azizollahi

Garcı́a-López

2020

Molecules

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“…[64,65] Acyclic iminyl radicals are characterized by reactions involving 1,n-hydrogen atom transfer (HAT, n = 5 in most cases, Scheme 1,b) or the intramolecular addition of iminyl radical to the C=C bond (Scheme 1, c). Synthetic applications of O-substituted oximes as precursors of iminyl radicals were recently summarized in several reviews, [66][67][68][69][70][71][72][73] but in these papers attention was focused mainly on ring-opening reactions of cyclic iminyl radicals (Scheme 1, a) and in part on addition reactions (Scheme 1, c). Only a few selected examples of the wide variety of intramolecular additions of iminyl radical to carbon-carbon π-bonds and iminyl radical mediated HAT processes were covered in the reviews devoted to hydroxylamine derivatives as nitrogen-radical precursors [74] and remote CÀ H functionalization by intramolecular HAT.…”

Section: Introductionmentioning

confidence: 99%

Oxime‐Derived Iminyl Radicals in Selective Processes of Hydrogen Atom Transfer and Addition to Carbon‐Carbon π‐Bonds

et al. 2021

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Oximes represent one of the fundamental organic compound classes with a wide range of synthetic applications. In the last decade O-substituted oximes were recognized as the synthetically available and versatile precursors of iminyl radicals via one-electron oxidation or one-electron reduction employing visible light photoredox catalysts, salts of abundant metals (such as Cu or Fe), or other convenient reagents. Iminyl radicals are powerful synthons for various processes of cyclization, ringopening, CH-functionalization, and coupling. The present review is focused on the synthetic methods based on oxime-derived iminyl radicals developed in the last few years excluding ring opening reactions of cyclic iminyl radicals that were summarized in recent publications. The review consists of two main parts:(1) reactions of iminyl radicals involving 1,n-hydrogen atom transfer (n = 5 in most cases) and (2) reactions involving the addition of iminyl radical to the carbon-carbon π-bond.

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“…Using this strategy, a range of chiral γ-amino acid derivatives could be achieved with high chemo-, regio-, and enantioselectivity. Recently, our group 45 – 48 and others 49 – 55 introduced readily accessible redox-active oxime derivatives as precursors to generate iminyl radicals under SET reduction or oxidation conditions (Fig. 1b ).…”

Section: Introductionmentioning

confidence: 99%

Asymmetric three-component olefin dicarbofunctionalization enabled by photoredox and copper dual catalysis

et al. 2021

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The intermolecular three-component alkene vicinal dicarbofunctionalization (DCF) reaction allows installation of two different carbon fragments. Despite extensive investigation into its ionic chemistry, the enantioseletive radical-mediated versions of DCF reactions remain largely unexplored. Herein, we report an intermolecular, enantioselective three-component radical vicinal dicarbofunctionalization reaction of olefins enabled by merger of radical addition and cross-coupling using photoredox and copper dual catalysis. Key to the success of this protocol relies on chemoselective addition of acyl and cyanoalkyl radicals, generated in situ from the redox-active oxime esters by a photocatalytic N-centered iminyl radical-triggered C-C bond cleavage event, onto the alkenes to form new carbon radicals. Single electron metalation of such newly formed carbon radicals to TMSCN-derived L1Cu(II)(CN)2 complex leads to asymmetric cross-coupling. This three-component process proceeds under mild conditions, and tolerates a diverse range of functionalities and synthetic handles, leading to valuable optically active β–cyano ketones and alkyldinitriles, respectively, in a highly enantioselective manner (>60 examples, up to 97% ee).

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Iminyl-Radical-Triggered C–C Bond Cleavage of Cycloketone Oxime Derivatives: Generation of Distal Cyano-Substituted Alkyl Radicals and Their Functionalization

Cited by 84 publications

References 54 publications

Recent Advances on Synthetic Methodology Merging C–H Functionalization and C–C Cleavage

Recent Advances on Synthetic Methodology Merging C–H Functionalization and C–C Cleavage

Oxime‐Derived Iminyl Radicals in Selective Processes of Hydrogen Atom Transfer and Addition to Carbon‐Carbon π‐Bonds

Asymmetric three-component olefin dicarbofunctionalization enabled by photoredox and copper dual catalysis

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