Visible‐Light‐Catalyzed Direct Benzylic C(sp<sup>3</sup>)–H Amination Reaction by Cross‐Dehydrogenative Coupling

Pandey, Ganesh; Laha, Ramkrishna

doi:10.1002/anie.201506990

Cited by 153 publications

(41 citation statements)

References 85 publications

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“…Similar to the iminyl radical generation, the use of hydroxylamine derivatives has turned out to be very efficient [128,139]. The generation of amidyl radicals using organophotoredox catalysis was first reported by Pandey and Laha in 2015 (Scheme 30) [146]. They developed an intermolecular crossdehydrogenative benzylic C(sp 3 ) amination between the aryl substrates 30.1 and the amides 30.2 for the synthesis of the Weinreb amides 30.3 using DCA (OD5) as an organic dye.…”

Section: Amidyl Radical Generationmentioning

confidence: 99%

See 1 more Smart Citation

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

Amos¹,

Garreau²,

Buzzetti³

et al. 2020

Beilstein J. Org. Chem.

109

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Organic dyes have emerged as a reliable class of photoredox catalysts. Their great structural variety combined with the easy fine-tuning of their electronic properties has unlocked new possibilities for the generation of reactive intermediates. In this review, we provide an overview of the available approaches to access reactive intermediates that employ organophotocatalysis. Our contribution is not a comprehensive description of the work in the area but rather focuses on key concepts, accompanied by a few selected illustrative examples. The review is organized along the type of reactive intermediates formed in the reaction, including C(sp3) and C(sp 2 ) carbon-, nitrogen-, oxygen-, and sulfur-centered radicals, open-shell charged species, and sensitized organic compounds.

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Section: Amidyl Radical Generationmentioning

confidence: 99%

“…Illustrative example for the photocatalytic oxidative generation of amidyl radicals from Weinreb amides: the cross-dehydrogenative benzylic C(sp 3 )-H amination reported by Pandey and Laha [146].…”

Section: Scheme 30mentioning

confidence: 99%

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

Amos¹,

Garreau²,

Buzzetti³

et al. 2020

Beilstein J. Org. Chem.

109

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“…The mechanistic studies revealed that both visible light and catalyst were required for the CÀ H fluorination, while a non-metal radical CÀ H abstraction is involved in the rate-limiting step. In another report, Pandey and Laha demonstrated a direct amination of benzylic CH bond via visible-light-mediated oneelectron photoredox oxidation affording the corresponding mono-aminated products in good to excellent yields (Scheme 48) [65] The cross-dehydrogenative coupling proposedly involved the benzylic CÀ H radical formation via hydrogen atom transfer to an aminyl radical followed by one electron oxidation of benzylic radical to form benzylcarbocation. The aminyl radical was generated from amine by one-electron oxidation in the presence of 9,10-dicyanoanthracene (DCA) at the singlet excited state.…”

Section: Visible Light and Photoredox-catalyzed Functionalizationmentioning

confidence: 99%

Benzylic Methylene Functionalizations of Diarylmethanes

Gulati

Gandhi

Laha

2020

Chemistry An Asian Journal

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Diarylmethanes are cardinal scaffolds by virtue of their unique structural feature including the presence of a benzylic CH 2 group that can be easily functionalized to generate a variety of fascinating molecules holding immense importance in pharmaceutical, agrochemical, and material sciences. While the originally developed protocols for benzylic CÀ H functionalization in diarylmethanes employing base-mediated and metal-catalyzed strategies are still actively used, they are joined by a new array of metal-free conditions, offering milder and benign conditions. With the recent surge of interest towards the synthesis of functionalized diarylmethanes, numerous choices are now available for a synthetic organic chemist to transform the benzylic CÀ H bond to CÀ C or CÀ X bond offering the synthesis of any molecule of choice. This review highlights benzylic methylene (CH 2) functionalizations of diaryl/heteroarylmethanes utilizing various base-mediated, transition-metal-catalyzed, and transition-metal free approaches for the synthesis of structurally diverse important organic molecules, often with a high chemo-, regio-and enantio-selectivity. This review also attempts to provide analysis of the scope and limitations, mechanistic understanding, and sustainability of the transformations.

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“…In 2015, Pandey's group reported a conceptually new and synthetically valuable cross dehydrogenative benzylic C(sp 3 )–H amination reaction by visible‐light photoredox catalysis, which employed DCA (9,10‐dicyanoanthracene, 169 ) as a visible‐light absorbing photoredox catalyst (Scheme ). This protocol has a broad substrate scope and high regioselectivity.…”

Section: C(sp3)‐h Functionalizationmentioning

confidence: 99%

Functionalization of C-H Bonds by Photoredox Catalysis

Jiang

et al. 2017

Chem. Rec.

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Visible-light photoredox catalysis has been successfully used in the functionalization of inert C-H bonds including C(sp )-H bonds of arenes and C(sp )-H bonds of aliphatic compounds over the past decade. These transformations are typically promoted by the process of single-electron-transfer (SET) between substrates and photo-excited photocatalyst upon visible light irradiation (household bulbs or LEDs). Compared with other synthetic strategies, such as the transition-metal catalysis and traditional radical reactions, visible-light photoredox approach has distinct advantages in terms of operational simplicity and practicability. Versatile direct functionalization of inert C(sp )-H and C(sp )-H bonds including alkylation, trifluoromethylation, arylation and amidation, has been achieved using this practical strategy.

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Visible‐Light‐Catalyzed Direct Benzylic C(sp³)–H Amination Reaction by Cross‐Dehydrogenative Coupling

Cited by 153 publications

References 85 publications

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

Benzylic Methylene Functionalizations of Diarylmethanes

Functionalization of C-H Bonds by Photoredox Catalysis

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Visible‐Light‐Catalyzed Direct Benzylic C(sp3)–H Amination Reaction by Cross‐Dehydrogenative Coupling

Cited by 153 publications

References 85 publications

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

Benzylic Methylene Functionalizations of Diarylmethanes

Functionalization of C-H Bonds by Photoredox Catalysis

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Product

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Visible‐Light‐Catalyzed Direct Benzylic C(sp³)–H Amination Reaction by Cross‐Dehydrogenative Coupling