A photoredox catalyzed iminyl radical-triggered C–C bond cleavage/addition/Kornblum oxidation cascade of oxime esters and styrenes: synthesis of ketonitriles

He, Bin-Qing; Yu, Xia; Wang, Peng‐Zi; Chen, Jia‐Rong; Xiao, Wen‐Jing

doi:10.1039/c8cc07072e

Cited by 83 publications

(40 citation statements)

References 55 publications

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“…In an interesting use of the Kornblum oxidation, the Chen and Xiao groups published a method that also relies on oxime fragmentation, but operates in tandem with a photoredox catalyzed iminyl radical‐triggered C−C bond cleavage/radical addition/Korblum oxidation cascade for the synthesis of ketonitriles (Scheme ) . Although complex in the sequence of mechanistic steps, this method is remarkably simple in its setup, as is characteristic of net‐neutral RPC processes.…”

Section: Photoredox‐mediated Net‐neutral Radical/polar Crossovermentioning

confidence: 99%

Photoredox‐Mediated Net‐Neutral Radical/Polar Crossover Reactions

Wiles

Molander

2020

Israel Journal of Chemistry

127

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Radical/Polar Crossover (RPC) chemistry is a rapidly growing subset of photoredox catalysis that is characterized by transformations featuring both radical and ionic modes of reactivity. Net-neutral RPC is particularly interesting in that both the single-electron oxidation and reduction steps occur through interaction with the photo-catalyst, thus precluding the need for exogenous oxidants or reductants. As such, these transformations facilitate rapid incorporation of molecular complexity while maintaining mild reaction conditions. This review covers recent advances in photoredox-mediated net-neutral RPC synthetic methods, with a particular emphasis on C-C bond-forming reactions.Keywords: photoredox catalysis · radical polar crossover · catalysis · redox-neutral · radical Photoredox-Mediated Net-Neutral Radical/Polar CrossoverReactions that occur through net-neutral RPC follow one of two mechanistic pathways. These two scenarios are dictated by photocatalyst quenching through either an oxidative or reductive single electron transfer (Scheme 1). In both pathways, an excited state photocatalyst is quenched by a radical progenitor via a single electron transfer to give a ground state photocatalyst and a radical intermediate. The radical intermediate may then participate in a variety of single electron [a] R.Scheme 4. Defluorinative alkylation of α-trifluoromethyl alkenes for the synthesis of gem-difluoroalkenes. Scheme 11. Decarboxylative cyclopropanation of electron-deficient olefins with carboxylates. Scheme 12. Lithium borates as radical precursors for radical/polar annulation of electron-deficient olefins. Scheme 13. Cyclopropanation of vinyl phosphonates and other Michael acceptors by chloromethyl bis(catecholato)silicate.Review Isr. J. Chem. 2020, 60, 281 -293 Scheme 14. RPC-enabled azirine oxidation/[3 + 2] cyclization/aromatization cascade for the synthesis of functionalized pyrroles. Scheme 15. Tandem carboxylation/functionalization of styrenes.Review Isr. J. Chem. 2020, 60, 281 -293 Scheme 22. Oxime fragmentation/Kornblum oxidation cascade for the synthesis of ketonitriles. Scheme 23. Difluoromethylation/Kornblum oxidation for the synthesis of β-fluorinated ketones.

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Section: Photoredox‐mediated Net‐neutral Radical/polar Crossovermentioning

confidence: 99%

Photoredox‐Mediated Net‐Neutral Radical/Polar Crossover Reactions

Wiles

Molander

2020

Israel Journal of Chemistry

127

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“…Subsequently, Chen and co-workers disclosed that the same carbocations can undergo Kornblum oxidation (Scheme 12). 24 In this reaction, DMSO serves not only as the reaction medium but also as a source of an oxygen atom. The reaction provides a novel method to access functionalized ketonitriles 34 under mild conditions.…”

Section: Scheme 9 Iron-catalyzed Decarboxylative Olefination Of Cyclomentioning

confidence: 99%

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

et al. 2020

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Alkyl nitriles are versatile building blocks in organic synthesis because the cyano group can be easily converted into other functional groups. Iminyl-radical-triggered C–C bond cleavage of cycloketone oxime derivatives provides a practical route to access distal cyano-substituted alkyl radicals, which has given chemists a new radical reaction platform for the synthesis of diverse alkyl nitriles. This review provides an overview of various types of radical cyanoalkylation via ring opening of cycloketone oxime derivatives.1 Introduction2 C–C Bond Formation2.1 Alkenes as Radical Acceptors2.2 Aromatic Rings as Radical Acceptors2.3 Organometallic Reagents as Radical Acceptors2.4 Cyanoalkyl-Radical-Triggered Cyclization Reactions2.5 Miscellaneous3 C–Heteroatom Bond Formation3.1 C–O Bond Formation3.2 C–N Bond Formation3.3 C–S Bond Formation3.4 C–Halogen Bond Formation3.5 C–B Bond Formation4 Conclusion

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“…Recently, Xiao and co‐workers developed a photoredox catalysed cascade reaction of styrene with cycloketone oxime esters for the synthesis of ketonitriles (δ‐cyano ketones) (Scheme ) . The iridium catalysed generation of iminyl radicals 58 a from cycloketone oxime esters triggers the C−C bond cleavage to form cyanoalkyl radical 58 b followed by radical addition to styrene 57 and finally Kornblum oxidation to produce δ‐cyano ketones.…”

Section: Ketone Synthesis Using Iridium (Ir) Based Photocatalystsmentioning

confidence: 99%

Recent Advances in Photoredox Methods for Ketone Synthesis

2020

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Synthesis of ketones is one of the most addressed problems in organic chemistry owing to their presence in a diverse array of drugs, pharmaceuticals, natural products and photosensitizers. Many of the limitations associated with the traditional approaches enabling the synthesis of ketones like creation of high energy acylating reagents, poor functional group tolerance, pre-activation of starting materials have been largely addressed with the advent of photoredox chemistry. This review summarizes the recent advances made in the photoredox catalyzed synthesis of ketones. 2 3 4 5 6 7 8

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A photoredox catalyzed iminyl radical-triggered C–C bond cleavage/addition/Kornblum oxidation cascade of oxime esters and styrenes: synthesis of ketonitriles

Abstract: A photoredox-catalyzed iminyl radical-triggered C–C bond cleavage/addition/Kornblum oxidation cascade of cycloketone oxime esters and styrenes in DMSO is described for the first time.

Cited by 83 publications

References 55 publications

Photoredox‐Mediated Net‐Neutral Radical/Polar Crossover Reactions

Photoredox‐Mediated Net‐Neutral Radical/Polar Crossover Reactions

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

Recent Advances in Photoredox Methods for Ketone Synthesis

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