Radical C−H‐Amination of Heteroarenes using Dual Initiation by Visible Light and Iodine

Lucchetti, Nicola; Tkacheva, Anastasia; Fantasia, Serena; Muñiz, Kilian

doi:10.1002/adsc.201800677

Cited by 28 publications

(22 citation statements)

References 74 publications

(10 reference statements)

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“…We were also interested to see if the chemistry could be extended to other benzo‐fused nitrogen heterocycles. Togo has previously demonstrated the synthesis of N ‐sulfonylated benzomorpholine derivatives through radical‐mediated direct amination,[9h], [9i] and so we attempted the formation of N ‐alkyl derivatives from readily‐available β‐aryloxyalkyl N ‐chloroamines. The N ‐methylbenzomorpholine 2p was isolated as an inseparable mixture 5:1 mixture with a chlorinated derivative in 48 % yield.…”

Section: Resultsmentioning

confidence: 99%

“…The use of electrophilic nitrogen‐centred radicals has been prominent amongst these approaches, and methods are available for the introduction of primary, secondary or tertiary amines, amides, imides, phosphonamides and sulfonamides and their derivatives. [7b], These methods generally require the (sometimes multistep) synthesis of precursors to the nitrogen‐centred radical, and approaches which allow the one‐pot formal oxidative coupling of N–H and aryl C–H bonds are synthetically more attractive. This is most commonly achieved by in situ activation of amine derivatives bearing electron‐withdrawing substituents,[7e], , [9a], [9c], [9e], [9h], [9i] and examples facilitating direct transfer of simple aliphatic amines are scarce: Nicewicz elegantly demonstrated direct photoredox‐catalysed union of primary amines with arenes to generate secondary arylamines .…”

Section: Introductionmentioning

confidence: 99%

“…[7b], These methods generally require the (sometimes multistep) synthesis of precursors to the nitrogen‐centred radical, and approaches which allow the one‐pot formal oxidative coupling of N–H and aryl C–H bonds are synthetically more attractive. This is most commonly achieved by in situ activation of amine derivatives bearing electron‐withdrawing substituents,[7e], , [9a], [9c], [9e], [9h], [9i] and examples facilitating direct transfer of simple aliphatic amines are scarce: Nicewicz elegantly demonstrated direct photoredox‐catalysed union of primary amines with arenes to generate secondary arylamines . The first reports of direct aromatic amination by aminium radicals were described by Minisci[5e], [5h] and Kompa,[5f], [5g] using N ‐chloroamines as the radical precursors under both photochemical and metal‐catalysed conditions.…”

Section: Introductionmentioning

confidence: 99%

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Iron‐Catalysed Direct Aromatic Amination withN‐Chloroamines

2019

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An optimized procedure for the direct intra‐ and intermolecular amination of aromatic C–H bonds with aminium radicals generated from N‐chloroamines under iron catalysis is reported. A range of substituted tetrahydroquinolines could be readily prepared, while extension to the synthesis of benzomorpholines was more limited in scope. A direct one‐pot variant was developed, allowing direct formal oxidative N–H/C–H coupling.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Iron‐Catalysed Direct Aromatic Amination withN‐Chloroamines

2019

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“…The reaction necessitates the utilization of a limited quantity of molecular iodine which through photochemical activation, in situ produces an iodine (I) reagent, which further acts as the inducer of the radical amination reaction (Scheme 170). [188] Konig bunch in 2019 talked about a visible light photochemical methodology for reasonable helicene functionalization at extremely mild reaction conditions. The photochemical reaction protocols permits the regiospecific and classic late‐stage functionalization of helicenes that can be effortlessly brought about either through the activation of C(sp 2 )−Br bonds in helicenes utilizing K 2 CO 3 as inorganic base or direct C(sp 2 )−H helicene bond functionalization by means of oxidative photoredox conditions (Scheme 171).…”

Section: Photochemical Methods Of C−h Functionalizationmentioning

confidence: 99%

Recent Advances in Functionalization of Pyrroles and their Translational Potential

Hunjan

Panday

Gupta

et al. 2021

The Chemical Record

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Among the known aromatic nitrogen heterocycles, pyrrole represents a privileged aromatic heterocycle ranging its occurrence in the key component of “pigments of life” to biologically active natural products to active pharmaceuticals. Pyrrole being an electron‐rich heteroaromatic compound, its predominant functionalization is legendary to aromatic electrophilic substitution reactions. Although a few excellent reviews on the functionalization of pyrroles including the reports by Baltazzi in 1963, Casiraghi and Rassu in 1995, and Banwell in 2006 are available, they are fragmentary and over fifteen years old, and do not cover the modern aspects of catalysis. A review covering a comprehensive package of direct functionalization on pyrroles via catalytic and non‐catalytic methods including their translational potential is described. Subsequent to statutory yet concise introduction, the classical functionalization on pyrroles using Lewis acids largely following an ionic mechanism is discussed. The subsequent discussion follows the various metal‐catalyzed C−H functionalization on pyrroles, which are otherwise difficult to implement by Lewis acids. A major emphasize is given on the radical based pyrrole functionalization under metal‐free oxidative conditions, which is otherwise poorly highlighted in the literature. Towards the end, the current development of pyrrole functionalization under photocatalyzed and electrochemical conditions is appended. Only a selected examples of substrates and important mechanisms are discussed for different methods highlighting their scopes and limitations. The aromatic nucleophillic substitution on pyrroles (being an electron‐rich heterocycle) happened to be the subject of recent investigations, which has also been covered accentuating their underlying conceptual development. Despite great achievements over the past several years in these areas, many challenges and problems are yet to be solved, which are all discussed in summary and outlook.

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“…[185] Muniz and co-workers developed a direct CÀ H amination of indoles using dual initiation through visible light and a small amount of molecular iodine (Scheme 121). [186] Firstly, the electron transfer between indole and iodine (III) reagent generates radical 355. Then, reaction of radical 355 with indole provides radical intermediate 356 via selective C2À N bond formation.…”

Section: Iodides Photocatalysismentioning

confidence: 99%

Recent Developments in Photo‐Catalyzed/Promoted Synthesis of Indoles and Their Functionalization: Reactions and Mechanisms

2020

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The use of clean and renewable light sources is increasingly common in organic synthesis due to its safety, practicality and economy. Recently, photoredox catalysis has shown great application values in organic transformations because of its advantages of environmentally friendly and abundant resources. Indoles and their derivatives (indolines, oxindoles and isatins) are the core skeletons of some important organic compounds and widely‐present in various natural products and pharmaceuticals with different biological activities. Therefore, the research on the synthesis and modification of indoles is particularly important for chemists and pharmacologists. This review summarizes the effects of photocatalysis on indole synthesis and modification in recent decades. These transformations are accomplished by using metal photocatalysts (i. e., Ir, Ru, Ni, Cu, Fe, Au, Rh, TiO2, etc.) or non‐metallic photocatalysts (i. e., Rose Bengal, Eosin Y, quinones, naphthols, N‐heterocyclic carbenes, carbazoles, pyrylium salts, etc.), or without the need of photocatalysts. The detailed mechanisms of these photo‐catalyzed/promoted organic reactions are also highlighted deeply. And we hope this review will be helpful to researchers interested in this promising field of photocatalyzed transformations.

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Radical C−H‐Amination of Heteroarenes using Dual Initiation by Visible Light and Iodine

Cited by 28 publications

References 74 publications

Iron‐Catalysed Direct Aromatic Amination withN‐Chloroamines

Iron‐Catalysed Direct Aromatic Amination withN‐Chloroamines

Recent Advances in Functionalization of Pyrroles and their Translational Potential

Recent Developments in Photo‐Catalyzed/Promoted Synthesis of Indoles and Their Functionalization: Reactions and Mechanisms

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