Visible light/Ir(III) photocatalytic initiation of xanthate-based radical-chain reactions: Xanthate group transfer and oxidative addition to aromatic systems

López‐Mendoza, Pedro; Díaz, John E.; Loaiza, Alix E.; Miranda, Luis D.

doi:10.1016/j.tet.2018.04.079

Cited by 21 publications

(21 citation statements)

References 33 publications

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“…In addition to alkenes,a lkyl halides,a nd cross-dehydrogenative coupling reactions,s ome other alkylating reagents have also been exploited for the direct and selective alkylation of electron-rich heteroarenes:t hese include alcohols, [155][156][157][158] carboxylic acids, [159] peroxides, [160] pyridinium salts, [90] N,N-dialkylanilines, [161] and carboxylic xanthates. [97,98,162] Theuse of alcohols as alkylating agents has been elegantly exploited by Yi for the ruthenium-catalyzed direct alkylation of alkenes with ac ationic ruthenium hydride complex [(C 6 H 6 )(PCy 3 )(CO)RuH] + BF 4 À . [155] Although mainly focused on the direct alkylation of alkenes,t he direct alkylation of benzofuran and N-methylindole using some aliphatic or benzylic alcohols has also been shown to proceed with high efficiency.M ore recently,h eterogeneous platinum catalysts have been shown by Shimizu to promote the C3-selective methylation of indoles with methanol (Scheme 55).…”

Section: Alkylation With Other Reagentsmentioning

confidence: 99%

Beyond Friedel and Crafts: Directed Alkylation of C−H Bonds in Arenes

2019

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The alkylation of arenes is one of the most fundamental transformations in chemical synthesis leading to privileged scaffolds in many areas of science. Classical methods for the introduction of alkyl groups to arenes are mostly based on the Friedel-Crafts reaction, radical additions, metallation or pre-functionalization of the arene: these methods however suffer from limitations in scope, efficiency and selectivity. Moreover, they are based on the innate reactivity of the starting arene, favoring the alkylation at a certain position and rendering the introduction of alkyl chains at other positions much more challenging. This can be addressed by the use of a directing group facilitating, in the presence of a metal catalyst, the regioselective alkylation of a C-H bond. These directed alkylations of C-H bonds in arenes are overviewed, in a comprehensive manner, in this review article.

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Section: Alkylation With Other Reagentsmentioning

confidence: 99%

Beyond Friedel and Crafts: Directed Alkylation of C−H Bonds in Arenes

2019

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“…The heteroarenes have to be substituted with electron‐withdrawing groups to achieve acceptable yields. More recently, Miranda developed a photoinduced, iridium‐catalyzed system to promote the same transformation on some indoles and pyrroles . As already mentioned in Sections 2.1.5 and 2.2.5, Zard utilized similar alkylating agents for the direct alkylation of various heteroarenes, including pyrroles and indoles …”

Section: Alkylation Of Heteroarenesmentioning

confidence: 99%

Beyond Friedel and Crafts: Innate Alkylation of C−H Bonds in Arenes

Evano

Theunissen

2019

Angew Chem Int Ed

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Alkylated arenes are ubiquitous molecules and building blocks commonly utilized in most areas of science where there is a need for small organic molecules. Despite its apparent simplicity, the regioselective alkylation of arenes is still a challenging transformation in a lot of cases. Classical methods for the introduction of alkyl groups on arenes, which include the venerable Friedel-Crafts reaction, radical additions, metallation or pre-functionalization of the arene, as well as alternatives such as the directed alkylation of C-H bonds, still suffer from severe limitations in terms of scope, efficiency and selectivity. This can be addressed by exploiting the innate reactivity of some (hetero)arenes, in which electronic and steric properties, governed (or not) by the presence of one (or multiple) heteroatom(s) ensure high levels of regioselectivity. These innate alkylations of C-H bonds in (hetero)arenes will be overviewed, in a comprehensive manner, in this review article.

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“…Herein, we report a photocatalytic degenerative radical transfer of xanthates to olefins using an iridium-based photocatalyst under blue LED irradiation (Scheme 1). A series of mechanistic investigations identified that the process involves a triplet-sensitization of the xanthates by the long-lived triplet state of the iridium-based photocatalyst that triggers the radical chain process [27].…”

Section: Introductionmentioning

confidence: 99%

Degenerative xanthate transfer to olefins under visible-light photocatalysis

Kaga¹,

Wu²,

Lim³

et al. 2018

Beilstein J. Org. Chem.

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The degenerative transfer of xanthates to olefins is enabled by the iridium-based photocatalyst [Ir{dF(CF3)ppy}2(dtbbpy)](PF6) under blue LED light irradiation. Detailed mechanistic investigations through kinetics and photophysical studies revealed that the process operates under a radical chain mechanism, which is initiated through triplet-sensitization of xanthates by the long-lived triplet state of the iridium-based photocatalyst.

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Visible light/Ir(III) photocatalytic initiation of xanthate-based radical-chain reactions: Xanthate group transfer and oxidative addition to aromatic systems

Cited by 21 publications

References 33 publications

Beyond Friedel and Crafts: Directed Alkylation of C−H Bonds in Arenes

Beyond Friedel and Crafts: Directed Alkylation of C−H Bonds in Arenes

Beyond Friedel and Crafts: Innate Alkylation of C−H Bonds in Arenes

Degenerative xanthate transfer to olefins under visible-light photocatalysis

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