Decarboxylative C–H Alkylation of Heteroarene <i>N</i>-Oxides by Visible Light/Copper Catalysis

Liu, Duanyang; Liu, Xu; Gao, Yan; Wang, Chaoqun; Tian, Jie‐Sheng; Loh, Teck‐Peng

doi:10.1021/acs.orglett.0c03382

Cited by 27 publications

(18 citation statements)

References 69 publications

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“…More recently, Loh, Tian, and co-workers employed hypervalent iodine(III) reagents 54.2 for site-selective alkylation of heteroarene N-oxides 54.1. 144 Iodine reagents bearing primary and secondary alkyl groups underwent smooth transformation with quinoline N-oxide to deliver the ortho-alkylation products in moderate to good yields (54.4−54.8). Tertiary alkylation was also feasible, albeit with diminished yield (54.9).…”

Section: General Overviewmentioning

confidence: 99%

Visible Light-Induced Transition Metal Catalysis

2021

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In recent years, visible light-induced transition metal catalysis has emerged as a new paradigm in organic photocatalysis, which has led to the discovery of unprecedented transformations as well as the improvement of known reactions. In this subfield of photocatalysis, a transition metal complex serves a double duty by harvesting photon energy and then enabling bond forming/breaking events mostly via a single catalytic cycle, thus contrasting the established dual photocatalysis in which an exogenous photosensitizer is employed. In addition, this approach often synergistically combines catalyst–substrate interaction with photoinduced process, a feature that is uncommon in conventional photoredox chemistry. This Review describes the early development and recent advances of this emerging field.

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Section: General Overviewmentioning

confidence: 99%

Visible Light-Induced Transition Metal Catalysis

2021

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“…In 2020, Loh, Tian, and co‐workers reported a highly site‐selective alkylation of heteroarene N ‐oxides (one example of 2,2‘‐bipyridine N ‐oxide) using hypervalent iodine(III) carboxylates as an alkylating agent in the presence of a cheap copper catalyst under visible light conditions (Scheme 24). [46] In contrast with two previous protocols, the reaction afforded the C6‐alkylated 2‘‐bipyridine N ‐oxide, not the reduced form. Cu(I) surrounded by 4,7‐diphenyl‐1,10‐phenanthroline (BPhen) is employed as the photoredox catalyst, and its photoexcited state can reduce hypervalent iodine‐(III) carboxylate to generate alkyl radical SET process.…”

Section: Late‐stage Functionalization Of 22’‐bipyridine Derivativesmentioning

confidence: 84%

Synthesis of 2,2’‐Bipyridines through Catalytic C−C Bond Formations from C−H Bonds

2021

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The present review describes the homogenous catalytic methodologies for the synthesis of 2,2’‐bipyridines involving C−C bond formation from C−H bond. There are three main approaches to build well‐decorated 2,2’‐bipyridines from C−H bond cleavage: i) the formation of C2−C2′ bond by the dimerization of (activated) pyridines, ii) the C−H bond heteroarylation of activated pyridine, or iii) the late‐stage functionalization of (activated) 2,2’‐bipyridines including photoredox processes. Besides the scope and limitation of each methodologies, the relevant mechanisms of reaction are also discussed.

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“…In 2020, Loh and co-workers [ 104 ] reported the copper-catalyzed highly site-selective alkylation of heteroarene N -oxides in the presence of hypervalent iodine III carboxylates. As an alkylating agent, the hypervalent iodine III carboxylates were reduced by active copper I complexes and produced an alkyl radical, which was then captured by a copper III active species.…”

Section: Reviewmentioning

confidence: 99%

Visible-light-mediated copper photocatalysis for organic syntheses

Wang¹,

Yan²,

Ma³

et al. 2021

Beilstein J. Org. Chem.

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Photoredox catalysis has been applied to renewable energy and green chemistry for many years. Ruthenium and iridium, which can be used as photoredox catalysts, are expensive and scarce in nature. Thus, the further development of catalysts based on these transition metals is discouraged. Alternative photocatalysts based on copper complexes are widely investigated, because they are abundant and less expensive. This review discusses the scope and application of photoinduced copper-based catalysis along with recent progress in this field. The special features and mechanisms of copper photocatalysis and highlights of the applications of the copper complexes to photocatalysis are reported. Copper-photocatalyzed reactions, including alkene and alkyne functionalization, organic halide functionalization, and alkyl C–H functionalization that have been reported over the past 5 years, are included.

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Decarboxylative C–H Alkylation of Heteroarene N-Oxides by Visible Light/Copper Catalysis

Cited by 27 publications

References 69 publications

Visible Light-Induced Transition Metal Catalysis

Visible Light-Induced Transition Metal Catalysis

Synthesis of 2,2’‐Bipyridines through Catalytic C−C Bond Formations from C−H Bonds

Visible-light-mediated copper photocatalysis for organic syntheses

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